This document summarizes a study that used terahertz spectroscopy to analyze the interaction between different dyes (natural dyes from pomegranate and blackberry, and an inorganic dye called Ruthenium) and titanium dioxide films. The study found that:
1) The terahertz spectra of the natural dye-sensitized films were similar to each other but distinct from the inorganic dye, with prominent absorption peaks around the same wavelengths.
2) The natural dyes permeated more uniformly through the titanium dioxide layers than the inorganic dye based on kinetic studies of dye penetration.
3) Surface profiling and 3D imaging of the films using terahertz radiation clearly showed defects and flaws on the titanium dioxide film.
A novel label-free cocaine assay based on aptamer-wrapped single-walled carbo...Nanomedicine Journal (NMJ)
Objective(s):
This paper describes a selective and sensitive biosensor based on the dissolution and aggregation of aptamer wrapped single-walled carbon nanotubes. We report on the direct detection of aptamer–cocaine interactions, namely between a DNA aptamer and cocaine molecules based on near-infrared absorption at λ807.
Materials and Methods:
First a DNA aptamer recognizing cocaine was non-covalently immobilized on the surface of single walled carbon nanotubes and consequently dissolution of SWNTs was occurred. Vis-NIR absorption (A807nm) of dispersed, soluble aptamer-SWNTs hybrid, before and after incubation with cocaine was measured using a CECIL9000 spectrophotometer.
Results:
This carbon nanotube setup enabled the reliable monitoring of the interaction of cocaine with its cognate aptamer by aggregation of SWNTs in the presence of cocaine.
Disscusion:
This assay system provides a mean for the label-free, concentration-dependent, and selective detection of cocaine with an observed detection limit of 49.5 nM.
International Journal of Computational Engineering Research(IJCER)ijceronline
International Journal of Computational Engineering Research(IJCER) is an intentional online Journal in English monthly publishing journal. This Journal publish original research work that contributes significantly to further the scientific knowledge in engineering and Technology.
CHEMICALLY DERIVED NANO-PIGMENT FOR ANTIBACTERIAL ACTIVITY, SURFACE COATING A...Jenson Samraj
This dissertation describes the properties of Nanopigment. The work which was furnished with lots of information about the antibacterial effects of the nanopigment.
A novel label-free cocaine assay based on aptamer-wrapped single-walled carbo...Nanomedicine Journal (NMJ)
Objective(s):
This paper describes a selective and sensitive biosensor based on the dissolution and aggregation of aptamer wrapped single-walled carbon nanotubes. We report on the direct detection of aptamer–cocaine interactions, namely between a DNA aptamer and cocaine molecules based on near-infrared absorption at λ807.
Materials and Methods:
First a DNA aptamer recognizing cocaine was non-covalently immobilized on the surface of single walled carbon nanotubes and consequently dissolution of SWNTs was occurred. Vis-NIR absorption (A807nm) of dispersed, soluble aptamer-SWNTs hybrid, before and after incubation with cocaine was measured using a CECIL9000 spectrophotometer.
Results:
This carbon nanotube setup enabled the reliable monitoring of the interaction of cocaine with its cognate aptamer by aggregation of SWNTs in the presence of cocaine.
Disscusion:
This assay system provides a mean for the label-free, concentration-dependent, and selective detection of cocaine with an observed detection limit of 49.5 nM.
International Journal of Computational Engineering Research(IJCER)ijceronline
International Journal of Computational Engineering Research(IJCER) is an intentional online Journal in English monthly publishing journal. This Journal publish original research work that contributes significantly to further the scientific knowledge in engineering and Technology.
CHEMICALLY DERIVED NANO-PIGMENT FOR ANTIBACTERIAL ACTIVITY, SURFACE COATING A...Jenson Samraj
This dissertation describes the properties of Nanopigment. The work which was furnished with lots of information about the antibacterial effects of the nanopigment.
In recent years there has been ever increasing activity and interest within the scientific and engineering fields about engineered nanoparticles (ENP). PerkinElmer's analytical instruments enable engineers and scientists to measure, characterize, and better understand nanomaterials for industrial and academic nanotechnology research. In this Nanotechnology Insights e-Zine you will find a wide range of solutions and scientific papers about nanomaterial applications (from synthesizing to end use) that illustrate PerkinElmer's support and contribution to customers working in this revolutionary science.
Synthesis and study of structural and magnetic properties of superparamagneti...Nanomedicine Journal (NMJ)
Objective(s):
This paper describes coating of magnetite nanoparticles (MNPs) with amorphous silica shells.
Materials and Methods:
First, magnetite (Fe3O4) NPs were synthesized by co-precipitation method and then treated with stabilizer molecule of trisodium citrate to enhance their dispersibility. Afterwards, coating with silica was carried out via a sol-gel approach in which the electrostatically stabilized MNPs were used as seeds. The samples were characterized by means of X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared (FT-IR) spectroscopy and vibrating sample magnetometer (VSM).
Results:
The results of XRD analysis implied that the prepared nanocomposite consists of two compounds of crystalline magnetite and amorphous silica that formation of their core/shell structure with the shell thickness of about 5 nm was confirmed by TEM images. The magnetic studies also indicated that produced Fe3O4@SiO2 core/shell nanocomposite exhibits superparamagnetic properties at room temperature.
Conclusion:
These core/shell structure due to having superparamagnetic property of Fe3O4 and unique properties of SiO2, offers a high potential for many biomedical applications.
Keywords
Magnetite; Silica; Core-shell structure; Superparamagnetism; Biomedical applications
Enlargement of biologically stimulated
investigational processes for the synthesis of nanoparticles is
budding into an important branch of nanotechnology. Eco
responsive methods of green mediated synthesis of nanoparticles
are the present research in the extremity of nanotechnology. The
bioreduction behavior of leaf extracts of Morinda citrifolia L.
(Rubiaceae) in the green synthesis of silver nanoparticles was
investigated employing UV/Visible Spectrophotometry, Particle
size analyzer, Zeta potential, Filed emission scanning electron
microscopy, Energy Dispersive X-ray Analysis and FourierTransform
Infrared Spectroscopy. The antifungal property of the
silver nanoparticles was tested against Candida albicans,
Candida tropicalis and Candida krusei. The Antifungal assay
tests Zone of inhibition revealed the concentrations of more than
10µl of silver nanoparticles were inhibited the growth of fungal
pathogens.
introduction to Tio2 nanostructures, properties of Tio2, current trends in biomedical application, general application of Tio2, synthesis of Tio2 nanoparticle by chemical route, characterization technique and objective.
In recent years there has been ever increasing activity and interest within the scientific and engineering fields about engineered nanoparticles (ENP). PerkinElmer's analytical instruments enable engineers and scientists to measure, characterize, and better understand nanomaterials for industrial and academic nanotechnology research. In this Nanotechnology Insights e-Zine you will find a wide range of solutions and scientific papers about nanomaterial applications (from synthesizing to end use) that illustrate PerkinElmer's support and contribution to customers working in this revolutionary science.
Synthesis and study of structural and magnetic properties of superparamagneti...Nanomedicine Journal (NMJ)
Objective(s):
This paper describes coating of magnetite nanoparticles (MNPs) with amorphous silica shells.
Materials and Methods:
First, magnetite (Fe3O4) NPs were synthesized by co-precipitation method and then treated with stabilizer molecule of trisodium citrate to enhance their dispersibility. Afterwards, coating with silica was carried out via a sol-gel approach in which the electrostatically stabilized MNPs were used as seeds. The samples were characterized by means of X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared (FT-IR) spectroscopy and vibrating sample magnetometer (VSM).
Results:
The results of XRD analysis implied that the prepared nanocomposite consists of two compounds of crystalline magnetite and amorphous silica that formation of their core/shell structure with the shell thickness of about 5 nm was confirmed by TEM images. The magnetic studies also indicated that produced Fe3O4@SiO2 core/shell nanocomposite exhibits superparamagnetic properties at room temperature.
Conclusion:
These core/shell structure due to having superparamagnetic property of Fe3O4 and unique properties of SiO2, offers a high potential for many biomedical applications.
Keywords
Magnetite; Silica; Core-shell structure; Superparamagnetism; Biomedical applications
Enlargement of biologically stimulated
investigational processes for the synthesis of nanoparticles is
budding into an important branch of nanotechnology. Eco
responsive methods of green mediated synthesis of nanoparticles
are the present research in the extremity of nanotechnology. The
bioreduction behavior of leaf extracts of Morinda citrifolia L.
(Rubiaceae) in the green synthesis of silver nanoparticles was
investigated employing UV/Visible Spectrophotometry, Particle
size analyzer, Zeta potential, Filed emission scanning electron
microscopy, Energy Dispersive X-ray Analysis and FourierTransform
Infrared Spectroscopy. The antifungal property of the
silver nanoparticles was tested against Candida albicans,
Candida tropicalis and Candida krusei. The Antifungal assay
tests Zone of inhibition revealed the concentrations of more than
10µl of silver nanoparticles were inhibited the growth of fungal
pathogens.
introduction to Tio2 nanostructures, properties of Tio2, current trends in biomedical application, general application of Tio2, synthesis of Tio2 nanoparticle by chemical route, characterization technique and objective.
Claves de la semana del 28 de septiembre al 4 de octubreCesce
Resumen de las noticias internacionales más destacadas del 28 de septiembre al 4 de octubre de 2013, elaborado por el departamento de Riesgo País de CESCE.
Abstract
Terahertz sub-surface imaging offers an effective solution for surface and 3D imaging because of minimal
sample preparation requirements and its ability to “see” below the surface. Another important property is the ability
to inspect on a layer-by layer basis via a non-contact route, non-destructive route. Terahertz 3D imager designed
at Applied Research and Photonics (Harrisburg, PA) has been used to demonstrate reconstructive imaging with a
resolution of less than a nanometer. Gridding with inverse distance to power equations has been described for 3D
image formation. A continuous wave terahertz source derived from dendrimer dipole excitation has been used for
reflection mode scanning in the three orthogonal directions. Both 2D and 3D images are generated for the analysis
of silver iodide quantum dots’ size parameter. Layer by layer image analysis has been outlined. Graphical analysis
was used for particle size and layer thickness determinations. The demonstrated results of quantum dot particle
size checks well with those determined by TEM micrograph and powder X-ray diffraction analysis. The reported
non-contact measurement system is expected to be useful for characterizing 2D and 3D naomaterials as well as for process development and/or quality inspection at the production line.
PRINCE2 Practitioner Exam Guide - by Ashish Dhoke (projectingIT)projectingIT
PRINCE2 Practitioner Exam Guide is designed by our faculty to help individuals and corporates to understand different aspects of PRINCE2 Practitioner Certification Exam described in brief below.
1] To Demonstrate whether a candidate can apply his learnings in a real world project environment
2] Exam Format
3] Themes
4] Processes
5] Structure of the Paper
6] Types of Questions
7] Time Management
8] Using the Manual
9] Results
10] FAQ
In case you need more information on the same, then do write us at info@projectingit.com
mathematics form 3 statistik.Formula yang mudah dan ringkas untuk memahami tajuk statistik.learn to use it right and it helps you to pass in your exams.
Synthesis and Energy Harvesting in Dye-Sensitized TiO2 PhotovoltaicsChandan B. Jal
After going through the literature review, it is understood that TiO2 is a high potential photoactive material. The doping of different metallic elements like Mg, Mn, Zr etc. decreases the band gap of TiO2 and place the material in a suitable range for photovoltaic application. Further studies reveal that TiO2 is a dye sensitive photocatalyst. In presence of different types of dye, photo absorption properties of TiO2 increases. In subsequent turn the optical properties of dye modified TiO2 shows enhanced properties in comparison to novice TiO2. Hence this attracts our attention to go for the study of the optical properties of dye modified TiO2. Another reason is that the dye that is chosen for the experiment is cost effective with better results as learned after the characterization. So, the present study has been undertaken for this project work.
Optical sensor based on dye-sensitized solar cell with tobacco chlorophyllTELKOMNIKA JOURNAL
Modified optical sensor based on dye-sensittized solar cell has been successfully fabricated to measure the number of light energy. The electric parameters as the sensor output were achieved from the light illuminance as the sensor input. The measured parameter from optical sensor according to the voltage and current output have been characterized to obtain the sensor performance. In this research, the modified sensor is customized from dye-sensitized solar cell with extracted tobacco chlorophyll dye as the photo-catalysator, photo-electrode of titanium dioxide and Iodine solution for redox reaction. The thick layer deposition with selected material is conducted using spin coating method of 1000 rpm. Based on the absorbance measurement, it shows that tobacco dye has the characteristics of visible light absorption in the wavelength of visible light spectra. The analytical result shows that the sensor has the wide linear characteristic in certain light illuminance and the increasing light intensity produces higher electrical parameter output both current and voltage. This sensor has potential prospect to be used as a light sensor and to be competitive fabrication cost.
Natural Dye-Sensitized Solar Cells (NDSSCs) From Opuntia Prickly Pear Dye Usi...IJERA Editor
Natural dye-sensitized solar cells (NDSSCs) have gained considerable attention in the field of solar energy due to their simple fabrication, good efficiency, and low production cost. Natural dyes are environmentally and economically superior to ruthenium-based dyes because they are nontoxic and cheap. However, the conversion efficiency of dye-sensitized solar cells based on natural dyes is low. One way to improve the DSSC performance is to enhance the absorptivity of extracted natural dyes. We investigated the influence of various factors in the extraction process, such as utilization of different extraction approaches, the acidity of extraction solvent, and different compounds of solvents on the optical absorption spectra. It was found that we could considerably enhance the optical absorptivity of dye and consequently the performance of DSSC by choosing a proper mixture of ethanol, methanol and water. In this study, a photo electrode using ZnO doped TiO2 nanoparticles was prepared by sol-gel method. In this paper we investigate the optical absorption, functional group, surface morphology and elementary composition of pure TiO2, ZnO doped TiO2 nanoparticles and opuntia prickly pear dye extract by using UV-Visible, PL-Studies, FT-IR, FE-SEM and EDS analysis. Finally photocurrent-voltaic characterization of nanocrystaline natural dye solar cell using I-V studies. It was found that the levels of short-circuit current (Jsc), open-circuit voltage (Voc), fill factor (FF) and overall conversion efficiency (η).
Growth and Characterisation of a New Semi–Organic Nonlinear Optical TTMZS Sin...Editor IJCATR
A new semi-organic nonlinear optical crystal called Tris Thiourea Magnesium Zinc sulphate (TTMZS) was synthesized.
TTMZS single crystals were grown from an aqueous solution using the Slow Evaporation method. The solubility of TTMZS was
determined for various temperatures. Single Crystal X-ray Diffraction (XRD) study was carried-out to identify the lattice parameters.
Various diffracting planes of the grown crystal were identified from the powder XRD study. Fourier Transform Infrared (FT-IR)
studies confirm the various functional groups present in the grown crystal. The transmission spectrum of this crystal shows that the
lower cut off wavelength lies at 280 nm. The thermal analysis confirmed that the crystal is stable up to 248.46°C. The Nonlinear
Optical (NLO) property of the grown crystal has been confirmed by Kurtz powder Second Harmonic Generation (SHG) test.
In this study, the development of Terahertz technology from past years to today, as well as the information and working principle about Terahertz technology are explained. In addition, various usage areas are given. Also the main topics are given below.
The general principles of the Terahertz Technology.
What is the Terahertz?
How can we generate the THz?
How can we detect it ?
Application areas of Terahertz technology
If there is a place you do not understand please contact me. (Mail, social media)
I hope you like. Please like and comment.
Similar to J uddinetal 2016_scientific_reports_interactiondyestio2 (20)
Terahertz (T-ray) techniques for measuring, profiling, and mapping of semiconductor features and doping concentration of via a T-ray volume imaging route, deep-level spectroscopy, and empirical modeling; and application thereof for semiconductor doping concentration thickness profiling and surface mapping for both undoped and doped semiconductors.
This paper outlines the basic technology and economic model of the core silicon technology. Silicon is the second most abundant element on the earth’s crust but there is no specific deposit or mine for silicon.
The only source for silicon is “sand” that the earth has an abundant supply. Here we outline the basic steps of manufacturing silicon ingot and wafers. It is projected that, once produced, these products will gain immediate market access, thus creating economic activities in a reasonably short period of time. The three initial products that could stem from the basic silicon ingot are silicon wafers, for both semiconductor and solar cell applications, and optical fiber for communication. This report focuses on the essential silicon
technology to produce silicon ingot, and silicon wafer, as the first step. Finally, the historic data available for the silicon wafer consumption per year have been modeled with the well-known Bass diffusion model.
It was found that with modified parameters, the Bass model fits the historic data well and the same model allows a projection for a few years in the future. This projected economic activities, therefore, encourages a social transformation towards a technological self-sufficiency.
Keywords: Silicon technology; Bass diffusion model; Silicon wafer consumption; Social transformation;
Technological self-sufficiency
DOI: 10.31031/NRS.2022.11.000760
Abstracts and Bios of the Chief Guest, Guest of Honor, distinguished Speakers and Panelists of the 2021 AABEA-FOBANA joint Seminar in Washington DC, November 27 and 28, 2021.
Lattice dilation of metallic nickel film deposited by plasma-spraying on a ceramic layer that is also prepared by plasma-spraying, has been investigated by high resolution terahertz imaging and sequential zooming of the images to quantify the lattice parameter by graphical analysis. A metallic nickel sample
was first imaged, and its measured lattice constant was found to be in agreement with the known value.
Subsequently, four additional samples containing plasma-sprayed nickel film have also been imaged via an identical procedure. The lattice images of all samples were used for graphical analysis and quantification of the respective lattice parameters. Four samples, viz., 77, 81, 129 and 111 have been analyzed and their lattice dilation was investigated. It was found that the lattice distance (d) of these samples is in the order as, d77 < d81 < d129 < d111 and higher than the value of metallic nickel. Unit cell volume and density were also calculated for each sample from the measured lattice parameter. The density was found in the decreasing order for the 4 samples; i.e., ρρρ ρ77 > ρ81 > ρ129 > ρ111 and the density values are significantly lower than the value for nickel. To our knowledge, this is the first direct evidence of the lattice dilation of plasma-sprayed metallic nickel measured via the terahertz lattice imaging, without requiring an electron microscope. Thus, the results presented herein establish an exciting extension of camera-less, reconstructive terahertz imaging technique that produces such a clear lattice image of nickel and allows to quantify the lattice parameter. The technique, however, is a general one, applicable to any material.
Abstract— This paper demonstrates overcoming of the Abbe diffraction limit (ADL) on image resolution. Here, terahertz multispectral reconstructive imaging has been described and used for analyzing nanometer size metal lines fabricated on a silicon wafer. It has also been demonstrated that while overcoming the ADL is a required condition, it is not sufficient to achieve sub-nanometer image resolution with longer wavelengths. A nanoscanning technology has been developed that exploits the modified Beer-Lambert’s law for creating a measured reflectance data matrix and utilizes the ‘inverse distance to power equation’ algorithm for achieving 3D, sub-nanometer image resolution. The nano-lines images reported herein, were compared to SEM images. The terahertz images of 70 nm lines agreed well with the TEM images. The 14 nm lines by SEM were determined to be ~15 nm. Thus, the wavelength dependent Abbe diffraction limit on image resolution has been overcome. Layer-by-layer analysis has been demonstrated where 3D images are analyzed on any of the three orthogonal planes. Images of grains on the metal lines have also been analyzed. Unlike electron microscopes, where the samples must be in the vacuum chamber and must be thin enough for electron beam transparency, terahertz imaging is non-destructive, non-contact technique without laborious sample preparation.
Abstract:
This paper demonstrates overcoming of the Abbe diffraction limit (ADL) on image resolution. Here, terahertz multispectral reconstructive imaging has been described and used for analyzing nanometer size metal lines fabricated on a silicon wafer. It has also been demonstrated that while overcoming the ADL is a required condition, it is not sufficient to achieve sub-nanometer image resolution with longer wavelengths. A nanoscanning technology has been developed that exploits the modified Beer-Lambert’s law for creating a measured reflectance data matrix and utilizes the ‘inverse distance to power equation’ algorithm for achieving 3D, sub-nanometer image resolution. The nano-lines images reported herein, were compared to SEM images. The terahertz images of 70 nm lines agreed well with the TEM images. The 14 nm lines by SEM were determined to be 15 nm. Thus, the wavelength dependent Abbe diffraction limit on image resolution has been overcome. Layer-by-layer analysis has been demonstrated where 3D images are analyzed on any of the three orthogonal planes. Images of grains on the metal lines have also been analyzed. Unlike electron microscopes, where the samples must be in the vacuum chamber and must be thin enough for electron beam transparency, terahertz imaging is non-destructive, non-contact technique without laborious sample preparation.
Two critical nanoscale design parameters (CNDPs); namely, surface chemistry and interior compositions of poly(amidoamine) (PAMAM) dendrimers were systematically engineered to produce unique hyperpolarizable, electro-optical substrates. These electro-optically active dendritic films were demonstrated to produce high quality, continuous wave terahertz radiation when exposed to a suitable pump laser that could be used for spectrometry and molecular imaging. These dendrimer based dipole excitation (DDE) terahertz sources were used to construct a working spectrometer suitable for many practical applications including THz imaging and analysis of encapsulated hydrogen species in fullerenes.
Abstract
Terahertz spectral analysis has been conducted on epitaxially grown semiconductor structures. Epitaxially grown semiconductors are important for microelectronic and optoelectronic devices and also for integrated circuits
fabricated using semiconductors. In this paper, we report results of terahertz time-domain spectroscopy of grown
SiGe layers on Ge buffer and separately a Ge buffer that was grown on a Si <001> wafer. In particular, evolution of
the time-domain spectra as a function of thickness of both samples was investigated by the terahertz pump-probe
technique. Representative spectra were analyzed to determine the respective layers’ spectral signatures. It was found that the spectroscopic analysis uniquely identified different layers by characteristic absorbance peaks. In addition, terahertz imaging was conducted in a non-destructive, non-contact mode for detecting lattice stacking fault and dislocations. Sub-surface imaging of grown SiGe layers on Ge buffer and that of the Ge buffer grown on a Si wafer reveals interesting lattice features in both samples. A comparison with TEM images of the samples exhibits that the terahertz image reproduces the dimensions found from TEM images within the experimental error limits. In particular, 3D images of both samples were generated by the terahertz reconstructive technique. The images were analyzed by graphical means to determine the respective layer thicknesses. Thus, this technique offers a versatile tool for both semiconductor research and in-line inspections.
Abstract: Non-destructive terahertz reflection interferometry offers many advantages for sub-surface inspection such as interrogation of hidden defects and measurement of layers’ thicknesses. Here, we describe a terahertz reflection interferometry (TRI) technique for non-contact measurement of paint panels where the paint is comprised of different layers of primer, basecoat, topcoat and clearcoat. Terahertz interferograms were generated by reflection from different layers of paints on a metallic substrate. These interferograms’ peak spacing arising from the delay-time response of respective layers, allow one to model the thicknesses of the constituent layers. Interferograms generated at different incident angles show that the interferograms are more pronounced at certain angles than others. This “optimum” angle is also a function of different paint and substrate combinations. An automated angular scanning algorithm helps visualizing the evolution of the interferograms as a function of incident angle and also enables the identification of optimum reflection angle for a given paint-substrate combination. Additionally, scanning at different points on a substrate reveals that there are observable variations from one point to another of the same sample over its entire surface area. This ability may be used as a quality control tool for in-situ inspection in a production line.
Electro-optic Dendrimer is used to generate milliwatts of terahertz power by difference frequency
method. A terahertz time-domain spectrometer (THz-TDS) has been designed around this source that
exhibits wide broadband terahertz range, 0.1 to 35 THz. Examples of molecular characterization are discussed
for three common explosives and the vibrational states of Fullerenes. The explosives’ spectra are
unique for each explosive that allow detection and identification of the species. The Fullerenes C60 and
H2@C60 also exhibit distinctively different spectra and absorbance states indicating that the THz-TDS is
suitable for probing increased number of vibrational states expected from molecular vibrations.
2011 Elsevier B.V. All rights reserved.
http://thz-pacifichem.blogspot.com/
Call for Abstracts
Advances in Terahertz Spectroscopy and Imaging (#413)
THE INTERNATIONAL CHEMICAL CONGRESS OF
PACIFIC BASIN SOCIETIES
Honolulu, Hawaii, USA DECEMBER 15 - 20, 2015
Dear Colleague:
It is our great pleasure to announce a symposium on “Advances in Terahertz Spectroscopy and Imaging” at the Pacifichem 2015 in Hawaii. Please see the link above for details. Contributions are solicited addressing subjects from all walks of terahertz applications. As an emerging area of science and technology, terahertz applications, such as spectroscopy, reflectometry and imaging, have the potential for addressing some of the critical problems of the 21st century. As indicated by increased attendance and number of papers in the past, the proposed symposium will fill a gap in the technical program by attracting the terahertz spectroscopy and related communities from all over the world. While there are other spectroscopic techniques, terahertz technology provides unique information that is not available from the predecessors. Therefore, this symposium solicits papers on the advances of terahertz applications in crucial matters such as: biomedical research, early detection of skin cancer, transdermal drug delivery, biopharmaceuticals, materials for energy, conservation and forensic science, security & screening, geology and minerals, semiconductors and any other relevant areas. This symposium will present an opportunity for the exchange of knowledge in a global forum, including results and discussions of current and breakthrough terahertz techniques and their applications. Papers, including spectroscopic, reflectometry and imaging techniques on the above mentioned areas and other terahertz applications in solving important problems are welcome. Formal abstracts submission will be open from January 1 – April 3, 2015. See this link for details of submission: http://www.pacifichem.org/congress-details/abstracts/
Sincerely yours,
Anis Rahman (USA): a.rahman@arphotonics.net
Choonho Kim (S Korea): chkim1202@gmail.com
Wolfgang Jaeger (Canada): wolfgang.jaeger@ualberta.ca
Sing Kiong Nguang (New Zealand): sk.nguang@auckland.ac.nz
Yacov Shamash (USA): yacovshamash@yahoo.com
Terahertz dynamic scanning reflectometry (TDSR) was used for measuring layered materials’ deformation kinetics
spectra. Multi-layered materials are used for protective devices such as helmet and body armor. An in-situ measurement of deformation profile and other dynamic characteristics is important when such material is subjected to ballistic impacts. Current instrumentation is limited in their abilities to provide sub-surface information in a non-destructive fashion. A high sensitivity TDSR has been used to measure dynamic surface deformation characteristics in real-time (in-situ) and also at post deformation (ex-situ). Real-time ballistic deformation kinetics was captured with a high speed measurement system. The kinetics spectra was used to compute a number of crucial parameters such as deformation
length and its propagation profile, the relaxation position, and the macroscopic vibration profile. In addition, the loss of mass due to impact was quantified for accurate determination of the trauma causing energy. For non-metallic substrates, a transmitted beam was used to calibrate mass loss, a priori, of the laminate layers due to impact. Deformation kinetics information may then be used to formulate trauma diagnosis conditions from blunt hit via the Sturdivan criterion [1].
The basic difference in the proposed approach is that here diagnostic criteria are inferred by measuring the helmet itself; no need to draw blood or any biopsy from the patient.
GDG Cloud Southlake #33: Boule & Rebala: Effective AppSec in SDLC using Deplo...James Anderson
Effective Application Security in Software Delivery lifecycle using Deployment Firewall and DBOM
The modern software delivery process (or the CI/CD process) includes many tools, distributed teams, open-source code, and cloud platforms. Constant focus on speed to release software to market, along with the traditional slow and manual security checks has caused gaps in continuous security as an important piece in the software supply chain. Today organizations feel more susceptible to external and internal cyber threats due to the vast attack surface in their applications supply chain and the lack of end-to-end governance and risk management.
The software team must secure its software delivery process to avoid vulnerability and security breaches. This needs to be achieved with existing tool chains and without extensive rework of the delivery processes. This talk will present strategies and techniques for providing visibility into the true risk of the existing vulnerabilities, preventing the introduction of security issues in the software, resolving vulnerabilities in production environments quickly, and capturing the deployment bill of materials (DBOM).
Speakers:
Bob Boule
Robert Boule is a technology enthusiast with PASSION for technology and making things work along with a knack for helping others understand how things work. He comes with around 20 years of solution engineering experience in application security, software continuous delivery, and SaaS platforms. He is known for his dynamic presentations in CI/CD and application security integrated in software delivery lifecycle.
Gopinath Rebala
Gopinath Rebala is the CTO of OpsMx, where he has overall responsibility for the machine learning and data processing architectures for Secure Software Delivery. Gopi also has a strong connection with our customers, leading design and architecture for strategic implementations. Gopi is a frequent speaker and well-known leader in continuous delivery and integrating security into software delivery.
Encryption in Microsoft 365 - ExpertsLive Netherlands 2024Albert Hoitingh
In this session I delve into the encryption technology used in Microsoft 365 and Microsoft Purview. Including the concepts of Customer Key and Double Key Encryption.
Unlocking Productivity: Leveraging the Potential of Copilot in Microsoft 365, a presentation by Christoforos Vlachos, Senior Solutions Manager – Modern Workplace, Uni Systems
zkStudyClub - Reef: Fast Succinct Non-Interactive Zero-Knowledge Regex ProofsAlex Pruden
This paper presents Reef, a system for generating publicly verifiable succinct non-interactive zero-knowledge proofs that a committed document matches or does not match a regular expression. We describe applications such as proving the strength of passwords, the provenance of email despite redactions, the validity of oblivious DNS queries, and the existence of mutations in DNA. Reef supports the Perl Compatible Regular Expression syntax, including wildcards, alternation, ranges, capture groups, Kleene star, negations, and lookarounds. Reef introduces a new type of automata, Skipping Alternating Finite Automata (SAFA), that skips irrelevant parts of a document when producing proofs without undermining soundness, and instantiates SAFA with a lookup argument. Our experimental evaluation confirms that Reef can generate proofs for documents with 32M characters; the proofs are small and cheap to verify (under a second).
Paper: https://eprint.iacr.org/2023/1886
How to Get CNIC Information System with Paksim Ga.pptxdanishmna97
Pakdata Cf is a groundbreaking system designed to streamline and facilitate access to CNIC information. This innovative platform leverages advanced technology to provide users with efficient and secure access to their CNIC details.
Sudheer Mechineni, Head of Application Frameworks, Standard Chartered Bank
Discover how Standard Chartered Bank harnessed the power of Neo4j to transform complex data access challenges into a dynamic, scalable graph database solution. This keynote will cover their journey from initial adoption to deploying a fully automated, enterprise-grade causal cluster, highlighting key strategies for modelling organisational changes and ensuring robust disaster recovery. Learn how these innovations have not only enhanced Standard Chartered Bank’s data infrastructure but also positioned them as pioneers in the banking sector’s adoption of graph technology.
Climate Impact of Software Testing at Nordic Testing DaysKari Kakkonen
My slides at Nordic Testing Days 6.6.2024
Climate impact / sustainability of software testing discussed on the talk. ICT and testing must carry their part of global responsibility to help with the climat warming. We can minimize the carbon footprint but we can also have a carbon handprint, a positive impact on the climate. Quality characteristics can be added with sustainability, and then measured continuously. Test environments can be used less, and in smaller scale and on demand. Test techniques can be used in optimizing or minimizing number of tests. Test automation can be used to speed up testing.
Enchancing adoption of Open Source Libraries. A case study on Albumentations.AIVladimir Iglovikov, Ph.D.
Presented by Vladimir Iglovikov:
- https://www.linkedin.com/in/iglovikov/
- https://x.com/viglovikov
- https://www.instagram.com/ternaus/
This presentation delves into the journey of Albumentations.ai, a highly successful open-source library for data augmentation.
Created out of a necessity for superior performance in Kaggle competitions, Albumentations has grown to become a widely used tool among data scientists and machine learning practitioners.
This case study covers various aspects, including:
People: The contributors and community that have supported Albumentations.
Metrics: The success indicators such as downloads, daily active users, GitHub stars, and financial contributions.
Challenges: The hurdles in monetizing open-source projects and measuring user engagement.
Development Practices: Best practices for creating, maintaining, and scaling open-source libraries, including code hygiene, CI/CD, and fast iteration.
Community Building: Strategies for making adoption easy, iterating quickly, and fostering a vibrant, engaged community.
Marketing: Both online and offline marketing tactics, focusing on real, impactful interactions and collaborations.
Mental Health: Maintaining balance and not feeling pressured by user demands.
Key insights include the importance of automation, making the adoption process seamless, and leveraging offline interactions for marketing. The presentation also emphasizes the need for continuous small improvements and building a friendly, inclusive community that contributes to the project's growth.
Vladimir Iglovikov brings his extensive experience as a Kaggle Grandmaster, ex-Staff ML Engineer at Lyft, sharing valuable lessons and practical advice for anyone looking to enhance the adoption of their open-source projects.
Explore more about Albumentations and join the community at:
GitHub: https://github.com/albumentations-team/albumentations
Website: https://albumentations.ai/
LinkedIn: https://www.linkedin.com/company/100504475
Twitter: https://x.com/albumentations
Removing Uninteresting Bytes in Software FuzzingAftab Hussain
Imagine a world where software fuzzing, the process of mutating bytes in test seeds to uncover hidden and erroneous program behaviors, becomes faster and more effective. A lot depends on the initial seeds, which can significantly dictate the trajectory of a fuzzing campaign, particularly in terms of how long it takes to uncover interesting behaviour in your code. We introduce DIAR, a technique designed to speedup fuzzing campaigns by pinpointing and eliminating those uninteresting bytes in the seeds. Picture this: instead of wasting valuable resources on meaningless mutations in large, bloated seeds, DIAR removes the unnecessary bytes, streamlining the entire process.
In this work, we equipped AFL, a popular fuzzer, with DIAR and examined two critical Linux libraries -- Libxml's xmllint, a tool for parsing xml documents, and Binutil's readelf, an essential debugging and security analysis command-line tool used to display detailed information about ELF (Executable and Linkable Format). Our preliminary results show that AFL+DIAR does not only discover new paths more quickly but also achieves higher coverage overall. This work thus showcases how starting with lean and optimized seeds can lead to faster, more comprehensive fuzzing campaigns -- and DIAR helps you find such seeds.
- These are slides of the talk given at IEEE International Conference on Software Testing Verification and Validation Workshop, ICSTW 2022.
UiPath Test Automation using UiPath Test Suite series, part 5DianaGray10
Welcome to UiPath Test Automation using UiPath Test Suite series part 5. In this session, we will cover CI/CD with devops.
Topics covered:
CI/CD with in UiPath
End-to-end overview of CI/CD pipeline with Azure devops
Speaker:
Lyndsey Byblow, Test Suite Sales Engineer @ UiPath, Inc.
In the rapidly evolving landscape of technologies, XML continues to play a vital role in structuring, storing, and transporting data across diverse systems. The recent advancements in artificial intelligence (AI) present new methodologies for enhancing XML development workflows, introducing efficiency, automation, and intelligent capabilities. This presentation will outline the scope and perspective of utilizing AI in XML development. The potential benefits and the possible pitfalls will be highlighted, providing a balanced view of the subject.
We will explore the capabilities of AI in understanding XML markup languages and autonomously creating structured XML content. Additionally, we will examine the capacity of AI to enrich plain text with appropriate XML markup. Practical examples and methodological guidelines will be provided to elucidate how AI can be effectively prompted to interpret and generate accurate XML markup.
Further emphasis will be placed on the role of AI in developing XSLT, or schemas such as XSD and Schematron. We will address the techniques and strategies adopted to create prompts for generating code, explaining code, or refactoring the code, and the results achieved.
The discussion will extend to how AI can be used to transform XML content. In particular, the focus will be on the use of AI XPath extension functions in XSLT, Schematron, Schematron Quick Fixes, or for XML content refactoring.
The presentation aims to deliver a comprehensive overview of AI usage in XML development, providing attendees with the necessary knowledge to make informed decisions. Whether you’re at the early stages of adopting AI or considering integrating it in advanced XML development, this presentation will cover all levels of expertise.
By highlighting the potential advantages and challenges of integrating AI with XML development tools and languages, the presentation seeks to inspire thoughtful conversation around the future of XML development. We’ll not only delve into the technical aspects of AI-powered XML development but also discuss practical implications and possible future directions.
Securing your Kubernetes cluster_ a step-by-step guide to success !KatiaHIMEUR1
Today, after several years of existence, an extremely active community and an ultra-dynamic ecosystem, Kubernetes has established itself as the de facto standard in container orchestration. Thanks to a wide range of managed services, it has never been so easy to set up a ready-to-use Kubernetes cluster.
However, this ease of use means that the subject of security in Kubernetes is often left for later, or even neglected. This exposes companies to significant risks.
In this talk, I'll show you step-by-step how to secure your Kubernetes cluster for greater peace of mind and reliability.
Why You Should Replace Windows 11 with Nitrux Linux 3.5.0 for enhanced perfor...SOFTTECHHUB
The choice of an operating system plays a pivotal role in shaping our computing experience. For decades, Microsoft's Windows has dominated the market, offering a familiar and widely adopted platform for personal and professional use. However, as technological advancements continue to push the boundaries of innovation, alternative operating systems have emerged, challenging the status quo and offering users a fresh perspective on computing.
One such alternative that has garnered significant attention and acclaim is Nitrux Linux 3.5.0, a sleek, powerful, and user-friendly Linux distribution that promises to redefine the way we interact with our devices. With its focus on performance, security, and customization, Nitrux Linux presents a compelling case for those seeking to break free from the constraints of proprietary software and embrace the freedom and flexibility of open-source computing.
Goodbye Windows 11: Make Way for Nitrux Linux 3.5.0!SOFTTECHHUB
As the digital landscape continually evolves, operating systems play a critical role in shaping user experiences and productivity. The launch of Nitrux Linux 3.5.0 marks a significant milestone, offering a robust alternative to traditional systems such as Windows 11. This article delves into the essence of Nitrux Linux 3.5.0, exploring its unique features, advantages, and how it stands as a compelling choice for both casual users and tech enthusiasts.
20 Comprehensive Checklist of Designing and Developing a WebsitePixlogix Infotech
Dive into the world of Website Designing and Developing with Pixlogix! Looking to create a stunning online presence? Look no further! Our comprehensive checklist covers everything you need to know to craft a website that stands out. From user-friendly design to seamless functionality, we've got you covered. Don't miss out on this invaluable resource! Check out our checklist now at Pixlogix and start your journey towards a captivating online presence today.
1. 1Scientific Reports | 6:30140 | DOI: 10.1038/srep30140
www.nature.com/scientificreports
Interaction of Sensitizing Dyes
with NanostructuredTiO2 Film in
Dye-Sensitized SolarCells Using
Terahertz Spectroscopy
William Ghann1
,Aunik Rahman2
,Anis Rahman2
& Jamal Uddin1
The objective of this investigation was to shed light on the nature of interaction of different organic
dyes and an inorganic dye, Ruthenium (II) polypyridine complex, withTiO2 nanoparticles.TiO2 is
commonly deployed as an efficient energy transfer electrode in dye sensitized solar cells.The efficiency
of dye sensitized solar cells is a function of the interaction of a dye with the electrode material such as
TiO2. To the best of our knowledge the present study is the first effort in the determination of terahertz
absorbance signals, investigation of real-time dye permeation kinetics, and the surface profiling and
3D imaging of dye sensitizedTiO2 films. Herein, we report that the terahertz spectra of the natural
dye sensitizedTiO2 films were distinctively different from that of the inorganic dye with prominent
absorption of natural dyes occurring at approximately the same wavelength. It was observed that
the permeation of the natural dyes were more uniform through the layers of the mesoporousTiO2
compared to the inorganic dye. Finally, defects and flaws onTiO2 film were easily recognized via surface
profiling and 3D imaging of the films.The findings thus offer a new approach in characterization of dye
sensitized solar cells.
Terahertz radiation (T-ray) based spectroscopy employs a range of wavelengths between the microwave and the
far-infrared region, from ~10 μm to ~3000 μm. Transient kinetics and different molecular resonances such as
vibrational states of materials may be probed with T-rays1–3
. Terahertz time-domain spectroscopy (THz-TDS)
has recently gained attention as a valuable tool for probing molecular transitions that are usually not captured
by other spectroscopic techniques such as UV, infrared and Raman spectroscopy4–6
. The non-ionizing and non-
invasive nature of the radiation coupled with its relative transparency to most materials except metals makes it
suitable for the analysis of biological structures in their native state.
Another major benefit of THz-TDS is time resolution, which is very important to the dynamics of certain
processes, allowing photo-induced responses to be characterized with sub-picosecond temporal resolution7
.
Terahertz spectrometry has been used in a number of applications including the investigation of the permea-
tion kinetics and concentration profile of active ingredients into the human stratum corneum8
, as well as other
biomedical9,10
, pharmaceutical11
, proteomics12,13
and genomics studies12,13
. Terahertz spectrometry has also been
used in the sensing and identification of explosives and other materials of security concerns14
.
The terahertz portion of the electromagnetic radiation is very sensitive to detailed structural properties as
well as charge migration and in recent times have been used to study the photoconductivity and the dynamics of
charge separation of several photovoltaic devices7,10,15–17
. Dye sensitized solar cells (DSSC) are a class of photovol-
taic devices that have been widely investigated due to advantages such as ease of fabrication, low cost, ecofriendly
nature and appreciable solar-to-electric energy conversion efficiency18–20
. DSSC comprises of a photoanode, an
electrolyte system for charge regeneration and a counter electrode. The present work focuses on the photoanode
which consist of a transparent conducting oxide (typically Indium doped Tin Oxide, ITO, or Fluorine doped Tin
Oxide, FTO) substrate covered with a thin film of titanium dioxide (TiO2) nanoparticles, and a dye21
. The dye
is used to sensitize the wide band gap TiO2 electrode. Upon illumination by solar energy, dye molecules absorb
photons and move to the excited states. The excited electrons are subsequently injected into the TiO2 conduction
1
Center for Nanotechnology for Department of Natural Sciences, Coppin State University, 2500 W. North Avenue,
Baltimore, MD 21216, USA. 2
Applied Research & Photonics, 470 Friendship Road, Suite 10, Harrisburg, PA 17111,
USA.Correspondence and requests for materials should be addressed to J.U. (email: juddin@coppin.edu)
received: 11April 2016
accepted: 29 June 2016
Published: 22 July 2016
OPEN
2. www.nature.com/scientificreports/
2Scientific Reports | 6:30140 | DOI: 10.1038/srep30140
Figure 1. Pomegranate sensitized TiO2 slide mounted on the XYZ-stage in the Terahertz probe setup.
Figure 2. Time-domain temporal signal (a–c); its corresponding Fourier transform broadband terahertz
absorbance spectra (d–f) of pomegranate (a,d) blackberry (b,e) and Rubpy (c,f) dye sensitized TiO2 on FTO
glass.
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3Scientific Reports | 6:30140 | DOI: 10.1038/srep30140
Figure 3. Fourier transform frequency spectra of three different dye sensitized TiO2 films (pomegranate,
blackberry and Rubpy) showing distinct absorbance characteristics.
Figure 4. Kinetics of permeation of three different dyes into TiO2 films coated on FTO glass: (a) Rubpy;
(b) pomegranate; (c) blackberry. Close-up view: (d) Rubpy; (e) pomegranate; (f) blackberry.
4. www.nature.com/scientificreports/
4Scientific Reports | 6:30140 | DOI: 10.1038/srep30140
band. An injected electron diffuses through the nanocrystalline TiO2 to the conductive film and then transferred
to an external circuit22–24
. An in-depth understanding of the interaction of dyes with the electron-transporting
TiO2 electrodes will form the basis for further research that will improve our understanding of the mechanisms of
charge generation and transport leading up to the production of electrical energy. A number of studies have been
carried out to investigate the influence of dye sensitization on the overall efficiency of solar cells25–28
.
In the present paper, T-rays have been used to investigate the interaction properties of the photoanode compo-
nent of the solar cell and could provide information on any defects that can potentially affect the overall efficiency
of dye sensitized solar cells. The TiO2 film provides an efficient scaffold to hold large amount of dye molecules
needed for light harvesting. However, if there are cracks in this scaffold, it reduces the number of dye molecules
adsorbed on the TiO2 and thus subsequently affect the efficiency of the solar cell. A means to detect cracks and
flaws in the TiO2 film and consequently the dye sensitized solar cell will thus help improve the fabrication of high
performance dye sensitized solar cells. The three dyes chosen for the studies were two different organic (pome-
granate and blackberry dye) and an inorganic dye, Ruthenium (II) polypyridine complex (Rubpy). The three
dyes were chosen mostly on the account of their strong absorption properties. Rubpy complexes are the most
common type of dye utilized in the fabrication of dye sensitized solar cells29
. Blackberry and Pomegranate, like
other natural dyes used in solar cell fabrication, have appreciable light absorption properties and preferable in
terms of their ecofriendly nature, low cost and abundance30–32
. The various anchoring groups on the dyes provide
means of attachment to the TiO2 surface. Herein is reported terahertz reflectometry and spectrometry studies on
dye sensitized titanium dioxide coated FTO glass plates commonly used in the fabrication of DSSC. Terahertz
measurements were carried out using a terahertz time-domain spectrometer with an attached nanoscanner as dis-
played in Fig. 1. The spectral features of the dyes adsorbed on TiO2 were studied using THz-TDS techniques and
its characteristic spectra ranging from 0 to 5 THz were obtained. A fast and effective methodology was developed
for the inspection and identification of defects on solar cells.
Results and Discussion
Spectroscopic Studies of Dye SensitizedTiO2 films. Teraspectra has been shown to be very sensitive
to various resonances in number of different molecules4,5
. Many materials exhibit distinct spectral absorption
features in the THz range of the electromagnetic spectrum and this makes possible the identification and charac-
terization of such materials33,34
. Terahertz radiation is sensitive to the vibrational states of an entire molecule and
terahertz spectra, accordingly, corresponds to molecular or inter-molecular behavior and provides information
unique to a given molecule or substance. As a result, no two molecules exhibit exactly identical terahertz absorb-
ance peaks as it is in the case of mid-infrared spectra which give intra-molecular information5
. Light absorption
by dye sensitized TiO2 coated FTO plates were investigated with the terahertz probe pulses. The terahertz charac-
teristic absorption spectra were obtained in the range of 0–35 THz. However, for the reason that too many peaks
placed on a single plot makes the plot very busy, only data in the range of 0–5 THz are reported in this paper. The
THz-TDS spectrometer generates data first in the time domain to which Fourier transform algorithms is applied
to obtain a frequency spectrum. Figure 2a–c exhibits the time-domain pulses (or interferogram) of the three dyes
studied. Although T-ray provides information about the entire molecule it could be seen that the interferogram
Figure 5. Diffusion characteristics of Rubpy, pomegranate, and blackberry dyes in mesoporous TiO2; (inset)
Depth scan of Rubpy dye sensitized TiO2 film. Top (red) scan of blank TiO2 film and bottom (blue) is the scan
after the TiO2 is saturated with Rubpy dye. The middle curve (green, right axis) is the difference of the top and
the bottom curves, indicating the distribution of the Rubpy dye across TiO2 film.
5. www.nature.com/scientificreports/
5Scientific Reports | 6:30140 | DOI: 10.1038/srep30140
of the natural dyes (Fig. 2a,b) follow the same trend as opposed to the inorganic dye. The time-domain signal in
Fig. 2a–c were Fourier transformed to obtain the terahertz spectra in Fig. 2d–f. The terahertz spectral features
obtained for the natural dyes were very similar to each other and had a lot of overlapping peaks when the three
spectra where displayed together in Fig. 3.
Pomegranate dye sensitized TiO2 films exhibited prominent absorption peaks at 0.33 THz, 0.97 THz, 1.99 THz,
2.85 THz, 3.54 THz and 4.48 THz. Blackberry dye sensitized TiO2 on the other hand exhibited prominent absorp-
tion peaks at 0.54 THz, 1.3 THz, 2.0 THz, 2.8 THz, 3.5 THz and 4.5 THz. The overlay of the spectra of all three
dyes in Fig. 3 shows that the absorption characteristics of the natural dyes are very similar: the absorption peaks
overlap with each other and are much sharper than the peaks of the Rubpy sensitized films. Rubpy sensitized TiO2
films had only high absorption peak at 0.97 THz which was comparable to that of pomegranate and blackberry
dye sensitized TiO2 films.
KineticStudies of DyeSensitizedTiO2 films. Kinetic studies were conducted on the three dye sensitized
TiO2 films to evaluate the rate at which the dyes diffuse through the TiO2 nanoparticle matrix. Aliquot 20 μL of
the dye was dropped on the film and the transient kinetics of diffusion of the dyes was recorded over a period of
500 seconds as the dyes permeated the titanium dioxide film. Figure 4 exhibits the characteristics of diffusion of
the respective dyes in titanium dioxide substrate. With all the dyes, there is an initial broad decrease in intensity
counts followed by an increase in intensity counts before they level off. Based on the slope of the curves in the first
100 seconds, Rubpy seems to have the fastest kinetics, reaching the peak of its intensity counts within 40 seconds
after the initial drop in intensity. After this increase in transmitted intensity, there is a gradual decrease in intensity
until it reaches a plateau. Rapid evaporation of the dye during the measurement, which most likely exposes some
Figure 6. Comparison of the surface plot of blank TiO2, blackberry, pomegranate and Rubpy dye sensitized
TiO2 film coated on FTO glass (Size of film scanned ~13000 × 13000 μm2
).
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6Scientific Reports | 6:30140 | DOI: 10.1038/srep30140
part of the titanium dioxide nanoparticles, could account for this sudden increase in intensity. Unlike pomegran-
ate and blackberry dyes which were used in their natural form, Rubpy solution was prepared by dissolving the
solid form in a suitable amount of deionized water and this could account for the rapid diffusion rate. After the
initial decrease in intensity upon application of the pomegranate dye, there is a gradual increase in intensity from
12 seconds after dye application to about 100 seconds after dye application. The intensity counts subsequently
decreases till it levels off. Blackberry dye has the slowest kinetics; after the initial drop in intensity counts upon
application of dye, it takes over 100 seconds to reach the maximum intensity and then steadily decrease in inten-
sity till it reaches a plateau. Rubpy diffusion reached saturation faster than both of the natural dyes as indicated
by flattening of its slope. Figure 4d–f shows a close-up of Fig. 4a–c where the X-axis is zoomed to 100 seconds.
It can be observed that the inorganic dye (Rubpy) shows an initial transmission count higher than that of FTO/
TiO2 substrate alone whereas pomegranate and blackberry show a decrease in intensity before slowly going up in
intensity count. This may be indicative of the fact that each of these dyes interact with the TiO2 nanoparticles in
their own unique way. Further investigation will be conducted for conclusive remarks on this observation.
Depth Scan Measurement of Dye SensitizedTiO2 films. The Terahertz scanning reflectometry was
used to assess the concentration profile of the different dyes into the TiO2 film. The technique has been previously
used to investigate the concentration profile of the active ingredients across the stratum corneum of the skin8
.
Depth scan of TiO2 films before and after saturation with the various dyes was carried out to assess their reflec-
tance at increasing depth and thereby understand the distribution of the dye in the titanium dioxide mesoporous
film. The scanning measurement was first carried out on the blank FTO/TiO2 film, as a control, after which 20 μL
of dye was applied and allowed to fully saturate the TiO2 layer. All the measurements were carried out under
identical conditions. A second scanning measurement was carried out after TiO2 was fully saturated with the
dye. The film was considered fully saturated when kinetics of the dye reached a steady state. The difference in
reflectance intensity of the FTO/TiO2 film saturated with the dye offers insight into the concentration of the dyes
across the depth of the TiO2 film. The intensity of terahertz radiation through a portion of the glass substrate was
also measured since it is dependent on the amount of light adsorbed in the Dye/TiO2 film. Figure 5 (inset) shows
the computation of the amount of Rubpy dye (green curve) from the scan of the blank (red curve) and saturated
substrate (blue curve). The result of the measurements as displayed in Fig. 5 show that the concentration of Rubpy
in the TiO2 is not uniform indicated by the increase in intensity with increasing depth of the mesoporous film.
Conversely, the permeation of the natural dyes are uniform through all the layers of the mesoporous TiO2 film.
Figure 7. Comparison of the 3D images of blank TiO2 blackberry, pomegranate and Rubpy dye sensitized TiO2
coated FTO film (Size of sample scanned ~13000 × 13000 μm2
).
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7Scientific Reports | 6:30140 | DOI: 10.1038/srep30140
The concentration of blackberry dye is, however, relatively more constant through the layers. This result corrobo-
rates with that of the kinetic study (Fig. 4) which shows Rubpy to have the fastest kinetics and blackberry dye with
the lowest kinetics. It can be deduced that the slower the kinetics the more uniform the concentration of the dye
across the depth of the substrate.
Surface Profiling and 3D Imaging of Dye SensitizedTiO2 films. The Terahertz scanning reflectom-
etry has shown promise as an important tool for obtaining tomographic information of the surface, subsurface,
and interaction of the constituents of a specimen. The Terahertz subsurface imaging was carried out to examine
nanoscopic features of TiO2 before and after the application of various dyes. Two different TiO2 film sizes were
scanned: 13000 × 13000 μm2
area (Figs 6 and 7) to give a general overview of the sample film and 4 × 4 μm2
area
(Figs 8 and 9) to obtain detailed features of the film. The surface plots (Figs 6 and 8) and 3D images (Figs 7 and 9)
were obtained for blank substrate (TiO2 alone); to serve as a control, and pomegranate, blackberry and Rubpy dye
diffused TiO2 film. The sizes of TiO2 films measured in microns are indicated on the coordinate axes.
In Figs 6 and 8, the intensity of reflected light is normalized for the blank TiO2 and all the dye sensitized TiO2
films for easy visual comparison of the degree to which each sample film reflect light. The intensity of reflected
light in Figs 7 and 9 on the other hand is not normalized for all the sample films and thus provide information
about the relative intensities of the different parts of a given sample film. It was observed from all the measure-
ments that the intensities of reflected light were not only based on the permeation of the dyes into TiO2 film but
also due in part to the thickness and morphology of the blank TiO2 film. Thin or exposed surfaces of the film
produced high intensity of reflected light whereas crests and ridges exhibited low intensity of reflected light.
Figure 8. Comparison of the surface plot of blackberry, pomegranate and Rubpy dye sensitized TiO2 film
coated on FTO glass with their corresponding blank TiO2 film coated on FTO glass. (Size of sample scanned
~4 × 4 μm2
).
8. www.nature.com/scientificreports/
8Scientific Reports | 6:30140 | DOI: 10.1038/srep30140
The reconstructed surface plots (Figs 6 and 8) clearly revealed exposed surfaces and defects present on the dye
sensitized TiO2 coated FTO glass substrate. A thicker spot near the center of the mesoporous TiO2 film created in
the process of spinning TiO2 paste on the FTO glass slides showed up as an artifact on the surface plot of the blank
TiO2 and all three dye sensitized TiO2 films. Some spots of the TiO2 film got detached from the FTO glass on
application of the dye resulting in higher intensity of reflected light as seen for Rubpy in Fig. 6. This is indicative
of a spin/dye dropping related change of the TiO2 film. The thicker spots are less obvious in the 4 × 4 μm2
film size
scan (Fig. 8) since the scan was performed outside of the main area with artifact.
The artifact was also visible on the 3D images (Fig. 7) and more prominently in Rubpy sensitized TiO2 film
where the exposed glass in the center of artifact is signified by high intensity of reflected light. A careful exami-
nation of 3D reconstructed image of the Rubpy sensitized TiO2 film (Fig. 7) shows a complete saturation of the
dye in the TiO2 matrix. The patches of light blue color may indicate dye evaporated from the surface of the TiO2.
The permeation characteristic of blackberry dye is similar to that of pomegranate (Figs 6 and 8). The intensity of
reflected light is low at the point of application of the dye but increases outwardly.
Detection of Defects Present of Dye Sensitized TiO2 Films. To confirm the unique capability of
Terahertz reflectometry to detect flaws present on the dye sensitized TiO2 films. A 10 mm × 23 mm portion of
25 mm × 25 mm dye sensitized TiO2 films were scanned to detect any defects present on the films. Pomegranate,
blackberry and Rubpy dye sensitized solar cell electrodes were scanned and with the measurements, 3-D images,
comparable to scanning electron microscopy images, were generated. As displayed in Fig. 10, the cracks present
in the TiO2 films show up as large peaks on the surface plots due to the greater intensity of reflected light from
the exposed glass surface. The magnitude of the peaks correlate with the size of the exposed surface area. Defects
are easily noticeable as they reflect more light. As displayed in Fig. 10, the protruding peaks in blackberry dye
sensitized TiO2 film (Fig. 10a) and pomegranate dye sensitized TiO2 film (Fig. 10b) are bigger than that of Rubpy
dye sensitized TiO2 film (Fig. 10c). These defects are not so much as a result of the dye application as it is the result
of the lack of uniformity of the layer of TiO2 on the glass substrate. The results demonstrate the unique defect
detection capabilities of Terahertz reflectometry and how it is well suited to efficiently detect flaws and malfunc-
tioning areas of solar cells.
Figure 9. Comparison of the 3D images of blackberry, pomegranate and Rubpy dye sensitized TiO2 film coated on
FTO glass with their corresponding blank TiO2 coated on FTO glass. (Size of film scanned ~4 × 4 μm2
).
9. www.nature.com/scientificreports/
9Scientific Reports | 6:30140 | DOI: 10.1038/srep30140
Conclusion
Terahertz spectrometry was used to study and characterize the interaction of two organic dyes (pomegranate and
blackberry) and an inorganic dye, Ruthenium (II) polypyridine complex (Rubpy) with mesoporous TiO2. A spec-
troscopic analysis exhibited similar terahertz absorbance peaks for the organic dye sensitized TiO2 films which were
different from the peaks of the inorganic dye sensitized TiO2 films. Diffusion kinetics and concentration distribution
profile of the applied dye into the TiO2 matrix revealed that Rubpy has the fastest kinetics and blackberry dye has
the slowest kinetics. In contrast to the inorganic dye, the organic dyes were uniform through the layers of the meso-
porous TiO2. Surface profiling and 3D imaging of dye sensitized TiO2 films revealed unevenness and flaws present
on the film and thus demonstrated the unique defect detection capability of Terahertz reflectometry. Terahertz spec-
trometry thus provides an effective means to optically measure dye sensitized TiO2 electrode properties prior to the
fabrication of DSSC.
Experimental Methods
Time-domain terahertz spectrometer. Terahertz measurements were carried out using a terahertz
time-domain spectrometer with an attached nanoscanner (TeraSpectra, Applied Research & Photonics, and
Harrisburg, PA). The spectrometer portion is similar to a setup described previously5
. Briefly; an electro-optic
dendrimer is excited by a pump laser, where continuous wave (CW) terahertz radiation is generated via a mech-
anism called dendrimer dipole excitation (DDE). This DDE source generates stable terahertz radiation over a
range of ~0.1 THz to ~30 THz at room temperature. The measurements are carried out in either a spectrometer
mode, for insight into molecular transition within a sample, or in a reflection mode for surface profiling and 3D
imaging. The navigation between the two modes is facilitated by a nanoscanner component of the instrument.
The nanoscanner position samples in the beam path for transmission measurements and also allows the scanning
of samples in three dimensions to probe the inner layers.
Figure 1 shows the TeraSpectra with the reflection module and a sample (pomegranate dye sensitized TiO2
film on FTO glass) mounted on the sample holder. During 3D imaging measurements, the terahertz beam first
hit the off-axis parabolic reflector and is focused on the sample at a 90 degree angle. The reflected beam from the
sample is directed to the detection system via the beam splitter as illustrated in Fig. 1 and Supplementary Figure
S1. 3D motion of the sample holder is facilitated by the nanoscanner enabling the interrogation of the reflectance
across all the three axis of the sample. Supplementary Figure S1 is a schematic set-up of terahertz scanning reflec-
tometry used for permeation kinetics and concentration profile of the dye in the sub surface of dye sensitized
titanium dioxide films.
Materials. The transparent conductive oxide coated polymer, FTO (1″ × 1″ or 2.5 cm × 2.5 cm) with coating
thickness of 4, 000 Angstrom was purchased from Hartford Glass Co. Inc. Titanium Dioxide Power (Degussa P25)
was procured from the institute of chemical education. Fresh fruit of pomegranate and blackberry, purchased in
Baltimore, were peeled and their dye extracted with a commercial juicer.
Figure 10. 10 mm × 23 mm Surface plots showing defects on dye sensitized TiO2 films: (a) blackberry;
(b) pomegranate; (c) Rubpy.
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10Scientific Reports | 6:30140 | DOI: 10.1038/srep30140
Sample Preparation. The FTO coated conductive glass served as the substrate for the preparation of the
samples. TiO2 paste, prepared according to a previously published procedure35
, was spread uniformly across the
conductive side of the glass using a spin coater. The TiO2 films were subsequently placed on a hot plate with a
surface temperature of 380 °C to anneal for over a period of 6 hours. They were then cooled down to room tem-
perature before the application of the freshly prepared dye. For spectral measurements and 3D imaging, the TiO2
films were immersed in the dye solution overnight and then rinsed with water and acetone before measurement.
Supplementary Figure S4 shows a schematic of the stages involved in the fabrication of the solar cells. For kinetic
studies, aliquot 20 μL of the respective dye was measured with a micropipette and dropped directly over TiO2
coated FTO film right before measurement.
Data Analysis. The experimental data obtained in time-domain signal (interferogram or terahertz pulse)
were analyzed using the Fourier transform of unevenly sampled data algorithm via commercially available soft-
ware package AutoSignal®v. 1.7 by SeaSolve Software Inc. The surface plots and 3D images wWere generated by
means of voxler®3 visualization software from Golden Software Inc. The data for kinetic studies were analyzed
via Microsoft Excel 2013.v.
References
1. Tonouchi, M. Cutting-edge terahertz technology. Nat Photon 1, 97–105 (2007).
2. McIntosh, A. I., Yang, B., Goldup, S. M., Watkinson, M. & Donnan, R. S. Terahertz spectroscopy: a powerful new tool for the
chemical sciences? Chem. Rev. 41, 2072–2082 (2012).
3. Beard, M. C., Turner, G. M. & Schmuttenmaer, C. A. Terahertz Spectroscopy. J. Phys. Chem 106, 7146–7159 (2002).
4. Rahman, A. Terahertz Spectrometry and Reflectometry: A New Frontier for Noninvasive Picoscale Investigations. Spectroscopy 28,
44–53 (2013).
5. Rahman, A. Dendrimer based terahertz time-domain spectroscopy and applications in molecular characterization. J. Mol. Struct.
1006, 59–65 (2011).
6. Schmuttenmaer, C. A. Exploring Dyanmics in the Far-Infrared with Terahertz Spectroscopy. Chem. Rev. 104, 1759 (2004).
7. Nemes, C. T., Koenigsmann, C. & Schmuttenmaer, C. A. Functioning Photoelectrochemical Devices Studied with Time-Resolved
Terahertz Spectroscopy. J. of Phys. Chem. Lett. 6, 3257–3262 (2015).
8. Rahman, A. et al. Diffision Kinetics & Permeation Concentration of Human Stratum Corneum Characterization by Terahertz
Scanning Reflectometry. Drug Dev. Del. 12, 43–49 (2012).
9. Bakopoulos, P. et al. A tunable continuous wave (CW) and short-pulse optical source for THz brain imaging applications. Mea. Sci.
Technol. 20, 104001 (2009).
10. Joseph, C. S., Yaroslavsky, A. N., Neel, V. A., Goyette, T. M. & Giles, R. H. Continuous wave terahertz transmission imaging of
nonmelanoma skin cancers. Lasers Surg. Med 43, 457–462 (2011).
11. Sibik, J., Löbmann, K., Rades, T. & Zeitler, J. A. Predicting Crystallization of Amorphous Drugs with Terahertz Spectroscopy. Mol.
Pharm. 12, 3062–3068 (2015).
12. Plusquellic, D. F., Siegrist, K., Heilweil, E. J. & Esenturk, O. Applications of terahertz spectroscopy in biosystems. Chemphyschem 8,
2412–2431 (2007).
13. Kutteruf, M. R. et al. Terahertz spectroscopy of short-chain polypeptides. Chem.Phys. Lett. 375, 337–343 (2003).
14. Liu, H. B., Zhong, H., Karpowicz, N., Chen, Y. & Zhang, X. C. Terahertz Spectroscopy and Imaging for Defense and Security
Applications. Proc. of the IEEE 95, 1514–1527 (2007).
15. Brauer, J. C., Marchioro, A., Paraecattil, A. A., Oskouei, A. A. & Moser, J.-E. Dynamics of Interfacial Charge Transfer States and
Carriers Separation in Dye-Sensitized Solar Cells: A Time-Resolved Terahertz Spectroscopy Study. J. Phys. Chem. C 119,
26266–26274 (2015).
16. Hendry, E., Koeberg, M., O’Regan, B. & Bonn, M. Local Field Effects on Electron Transport in Nanostructed TiO2 Revealed by
Terahertz Spectroscopy. Nano Lett. 6, 755 (2006).
17. Němec, H., Kužel, P. & Sundström, V. Charge transport in nanostructured materials for solar energy conversion studied by time-
resolved terahertz spectroscopy. J. Photochem. Photobiol. A 215, 123 (2010).
18. O’Regan, B. & Gratzel, M. A low-cost, high-efficiency solar cell based on dye-sensitized colloidal TiO2 films. Nature 353, 737–740
(1991).
19. Cherepy, N. J., Smestad, G. P., Grätzel, M. & Zhang, J. Z. Ultrafast Electron Injection: Implications for a Photoelectrochemical Cell
Utilizing an Anthocyanin Dye-Sensitized TiO2 Nanocrystalline Electrode. J. Phys. Chem. 101, 9342–9351 (1997).
20. Hagfeldt, A., Boschloo, G., Sun, L., Kloo, L. & Pettersson, H. Dye-Sensitized Solar Cells. Chem. Rev. 110, 6595 (2010).
21. Shalini, S., Balasundara prabhu, R., Prasanna, S., Mallick, T. K. & Senthilarasu, S. Review on natural dye sensitized solar cells:
Operation, materials and methods. Renew. and Sust. Energ. Rev. 51, 1306–1325 (2015).
22. Koyama, Y., Miki, T., Wang, X.-F. & Nagae, H. Dye-Sensitized Solar Cells Based on the Principles and Materials of Photosynthesis:
Mechanisms of Suppression and Enhancement of Photocurrent and Conversion Efficiency. Int. J. Mol. Sci. 10, 4575–4622 (2009).
23. Milot, R. L., Moore, G. F., Crabtree, R. H., Brudvig, G. W. & Schmuttenmaer, C. A. Electron Injection Dynamics from Photoexcited
Porphyrin Dyes into SnO2 and TiO2 Nanoparticles. The J. Phys. Chem. C 117, 21662–21670 (2013).
24. Watson, D. F. & Meyer, G. J. Electron injection at dye-sensitized semiconductor electrodes. Annu Rev Phys Chem. 56, 119–156
(2005).
25. Tiwana, P., Parkinson, P., Johnston, M. B., Snaith, H. J. & Herz, L. M. Ultrafast Terahertz Conductivity Dynamics in Mesoporous
TiO2: Influence of Dye Sensitization and Surface Treatment in Solid-State Dye-Sensitized Solar Cells. The J. of Phys. Chem. 114,
1365–1371 (2010).
26. Nemec, H. et al. Ultrafast terahert photoconductivity in nanocrystalline mesoporous TiO2 films. App. Physics Lett. 96,
0621031–0621033 (2010).
27. Koshiya, S., Yamashita, S. & Kimoto, K. Microscopic observation of dye molecules for solar cells on a titania surface. Sci Rep. 6,
24616 (2016).
28. Nazeeruddin, M. K., Humphry-Baker, R., Liska, P. & Grätzel, M. Investigation of Sensitizer Adsorption and the Influence of Protons
on Current and Voltage of a Dye-Sensitized Nanocrystalline TiO2 Solar Cell. The J. of Phys. Chem. B 107, 8981–8987 (2003).
29. Nazeeruddin, M. K., Klein, C., Liska, P. & Grätzel, M. Synthesis of novel ruthenium sensitizers and their application in dye-sensitized
solar cells. Coord Chem. Rev. 249, 1460–1467 (2005).
30. Hug, H., Bader, M., Mair, P. & Glatzel, T. Biophotovoltaics: Natural pigments in dye-sensitized solar cells. Appl. Energy 115, 216–225
(2014).
31. Hao, S., Wu, J., Huang, Y. & Lin, J. Natural dyes as photosensitizers for dye-sensitized solar cell. Sol. Energy 80, 209–214 (2006).
32. Hosseinnezhad, M., Moradian, S. & Gharanjig, K. Fruit extract dyes as photosensitizers in solar cells. Cur. Sci. 109, 953–956 (2015).
33. Chen, Y. et al. THz spectroscopic investigation of 2,4-dinitrotoluene. Chem. Phys. Lett. 400, 357–361 (2004).
11. www.nature.com/scientificreports/
11Scientific Reports | 6:30140 | DOI: 10.1038/srep30140
34. Yu, B. et al. Torsional vibrational modes of tryptophan studied by terahertz time-domain spectroscopy. Biophys J 86, 1649–1654
(2004).
35. Amadi, L. et al. Creation of Natural Dye Sensitized Solar Cell Using Nanostructured Titanium Oxide. Nanosci. Nanoeng. 3, 25–35
(2015).
Acknowledgements
The work was financially supported by the University of Maryland System (Wilson E. Elkins Professorship),
Constellation, an Exelon Company (E2
- Energy to Educate grant program) and Dept of Education (SAFRA
Title III Grant). The authors are also grateful to the Institution of Advancement, Coppin State University, for
administrative help. The content is exclusively the responsibility of the authors and does not necessarily represent
the offical views of the funding agencies.
AuthorContributions
J.U. and Anis R. conceived the idea and reviewed the final manuscript. W.G. and Aunik R. designed the
experiments. W.G. performed the experiments and wrote the manuscript with the assisitance of J.U. All authors
participated in the discussion and commented on the paper.
Additional Information
Supplementary information accompanies this paper at http://www.nature.com/srep
Competing financial interests: The authors declare no competing financial interests.
How to cite this article: Ghann, W. et al. Interaction of Sensitizing Dyes with Nanostructured TiO2 Film in
Dye-Sensitized Solar Cells Using Terahertz Spectroscopy. Sci. Rep. 6, 30140; doi: 10.1038/srep30140 (2016).
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