1) Eric Betzig, Stefan W. Hell and William E. Moerner were awarded the 2014 Nobel Prize in Chemistry for developing super-resolved fluorescence microscopy techniques that allow visualization of structures smaller than the diffraction limit of light.
2) Stefan Hell developed stimulated emission depletion (STED) microscopy, which uses a scanning "nanoscopic flashlight" to achieve resolutions better than 0.2 micrometers.
3) William E. Moerner was the first to detect fluorescence from a single molecule, opening up the field of single-molecule microscopy.
1) Stefan Hell invented STED microscopy in 1994 as a way to circumvent the diffraction limit of optical microscopes. STED microscopy uses two overlapping light pulses, one to excite fluorescent molecules and the other ("depletion pulse") to turn off fluorescence around the edge of the excited area.
2) The depletion pulse has an annular shape to efficiently deplete the excited state of molecules. Scanning the sample with these light sources allows creating a higher resolution image than traditional microscopy.
3) STED microscopy helped scientists study interactions between individual molecules inside cells and revealed various cell growth mechanisms, with applications in biology and medicine. For this breakthrough work, Stefan Hell was awarded the 2014 Nobel Prize in Chemistry.
The document is a ratification page for a report on using a microscope. It includes the name, student ID number, class, and group of the student who authored the report, Shally Rahmawaty. It also includes the signatures and IDs of the assistant and assistant coordinator who reviewed the report and accepted it, dated November 2013 in Makassar.
The document provides a detailed history of the development of the microscope from its invention in the 16th century to recent advances in super-resolution microscopy. It describes key milestones such as the earliest compound microscope in 1609, the first observation of living cells in 1676, and the invention of the electron microscope in 1931. It also outlines the main types of microscopes including compound, stereo, inverted, metallurgical, and polarizing microscopes and their typical uses.
This presentation shows a basic overview of all aspects of Fluorescence Microscopy including its description, history, mechanism, applications, advantages, limitations, and some examples of studies that used this technique.
Sir George Stokes first observed fluorescence in the mineral fluorspar when it was illuminated with ultraviolet light in the mid-19th century. He coined the term "fluorescence" to describe this phenomenon. A fluorescence microscope uses a high intensity light source to excite fluorescent molecules in a stained sample, which then emit light of a longer wavelength to produce a magnified image, whereas a conventional microscope uses visible light alone.
A whole new world in Biology is exposed. Cells can now be "dissected" into nanometre thin "slices" while at the same time the composition and 3-D ultrastructure of each "slice", using Nano Scanning Auger Microscopy, are determined
by
Prof. J.L.F. Kock (Ph.D.)
Department of Microbial, Biochemical and Food Biotechnology
University of the Free State
P. O. Box 339
Bloemfontein 9300
South Africa
This presentation has been delivered to "Online Medical Conference" at http://conferences.medicalia.org
Biophysics by the sea 2016 program and abstract bookDirk Hähnel
Biophysics by the sea 2016 program and abstract book
International conference on fluorescence super-resolution microscopy, spectroscopy, molecular cell mechanics and theoretical neurophysics
26th. -30th. september 2016
Pollentia resort, Alcudia, Spain
Event organizer:
Georg August University
Third Institute of Physics
Dirk Hähnel
37077 Göttingen
1) Stefan Hell invented STED microscopy in 1994 as a way to circumvent the diffraction limit of optical microscopes. STED microscopy uses two overlapping light pulses, one to excite fluorescent molecules and the other ("depletion pulse") to turn off fluorescence around the edge of the excited area.
2) The depletion pulse has an annular shape to efficiently deplete the excited state of molecules. Scanning the sample with these light sources allows creating a higher resolution image than traditional microscopy.
3) STED microscopy helped scientists study interactions between individual molecules inside cells and revealed various cell growth mechanisms, with applications in biology and medicine. For this breakthrough work, Stefan Hell was awarded the 2014 Nobel Prize in Chemistry.
The document is a ratification page for a report on using a microscope. It includes the name, student ID number, class, and group of the student who authored the report, Shally Rahmawaty. It also includes the signatures and IDs of the assistant and assistant coordinator who reviewed the report and accepted it, dated November 2013 in Makassar.
The document provides a detailed history of the development of the microscope from its invention in the 16th century to recent advances in super-resolution microscopy. It describes key milestones such as the earliest compound microscope in 1609, the first observation of living cells in 1676, and the invention of the electron microscope in 1931. It also outlines the main types of microscopes including compound, stereo, inverted, metallurgical, and polarizing microscopes and their typical uses.
This presentation shows a basic overview of all aspects of Fluorescence Microscopy including its description, history, mechanism, applications, advantages, limitations, and some examples of studies that used this technique.
Sir George Stokes first observed fluorescence in the mineral fluorspar when it was illuminated with ultraviolet light in the mid-19th century. He coined the term "fluorescence" to describe this phenomenon. A fluorescence microscope uses a high intensity light source to excite fluorescent molecules in a stained sample, which then emit light of a longer wavelength to produce a magnified image, whereas a conventional microscope uses visible light alone.
A whole new world in Biology is exposed. Cells can now be "dissected" into nanometre thin "slices" while at the same time the composition and 3-D ultrastructure of each "slice", using Nano Scanning Auger Microscopy, are determined
by
Prof. J.L.F. Kock (Ph.D.)
Department of Microbial, Biochemical and Food Biotechnology
University of the Free State
P. O. Box 339
Bloemfontein 9300
South Africa
This presentation has been delivered to "Online Medical Conference" at http://conferences.medicalia.org
Biophysics by the sea 2016 program and abstract bookDirk Hähnel
Biophysics by the sea 2016 program and abstract book
International conference on fluorescence super-resolution microscopy, spectroscopy, molecular cell mechanics and theoretical neurophysics
26th. -30th. september 2016
Pollentia resort, Alcudia, Spain
Event organizer:
Georg August University
Third Institute of Physics
Dirk Hähnel
37077 Göttingen
Novel color photography using a high-effi ciencyprobe can super-focus white l...Janique Goff Madison
Scientists have developed new materials for next-generation electronics so tiny that they are notonly indistinguishable when closely packed, but they also don't refl ect enough light to show fi nedetails, such as colors, with even the most powerful optical microscopes. Under an opticalmicroscope, carbon nanotubes, for example, look grayish. The inability to distinguish fi ne detailsand differences between individual pieces of nanomaterials makes it hard for scientists to studytheir unique properties and discover ways to perfect them for industrial use.
its about the microscopes types and there significance in the world for diagnostic purposes .advantages and disadvantages of the types of different microscopes
Laporan Praktikum Biologi Dasar - How to use the microscopeWiwi Pratiwie
The document provides instructions for using a microscope correctly and safely. It was a report from a biology practicum conducted by Nur Pratiwi. The practicum taught students how to use microscopes to observe the smallest structures of organisms. It covered preparing the microscope, controlling the light, adjusting the lens distance, making simple microscope slides, and changing magnifications. The goal was for students to learn proper microscope procedures.
Fluorescence microscope by Subhankar DasSubhankar Das
Fluorescence microscopy uses fluorescence from organic or inorganic dyes to visualize structures within cells or tissues. It provides high resolution and contrast compared to traditional microscopy. The microscope uses a mercury lamp light source and filters to excite fluorescent dyes, which then emit light of longer wavelengths. Common fluorescent dyes include fluorescein and rhodamine. Immunfluorescence microscopy labels structures with fluorescent antibody conjugates. Photobleaching limits fluorescence over time due to excited dye molecules interacting with oxygen before emission.
The document discusses electron microscopes. It begins by explaining that Ernst Ruska built the first electron microscope in 1931 using a beam of accelerated electrons for illumination. It then describes the key components of an electron microscope, including the electron gun, condenser lenses, specimen holder, and viewing system. Electron microscopes use electromagnetic lenses and have very high magnification and resolution, allowing observation at the nanoscale. However, specimens must be dried and ultra-thin to be viewed. Electron microscopes are used widely in science and industry.
- The document discusses the discovery of cells and the development of the cell theory. It describes how early microscopes allowed scientists like Robert Hooke and Anton van Leeuwenhoek to first observe cells. The cell theory states that all living things are made of cells, cells are the basic unit of structure and function, and new cells are produced from existing cells.
- The document then explains different types of microscopes like light microscopes, fluorescence microscopes, transmission electron microscopes, and scanning electron microscopes that have allowed scientists to study cells at different levels of magnification.
- The final sections describe the differences between prokaryotic and eukaryotic cells, noting that prokaryotes lack nuclei while
The document summarizes the history and components of the confocal microscope. It describes how the confocal microscope was initially conceived in the 1950s but lacked the necessary light sources and computing power. Work in the late 1960s adapted the original concept and allowed for the examination of unstained brain and ganglion cells. Further developments in lasers and computing through the 1980s led to more practical confocal microscopes. Modern confocal microscopes integrate optics, detectors, computers and lasers to produce high-resolution 3D electronic images of samples. Confocal microscopes are now used across various fields including biology and medicine.
Fluorescence microscopy uses fluorescent dyes and high intensity light to illuminate stained samples, which emit light of a longer wavelength. The image is based on this emitted light rather than the illuminating light. Key components include a light source, excitation and emission filters, and a dichroic mirror to separate the excitation and emission wavelengths. Fluorescence microscopy is widely used in biological research to identify structures, label cellular components, and study dynamic behaviors through live-cell imaging.
Fluorescence microscopy uses fluorescent dyes and ultraviolet light to study samples. When exposed to UV light, the dyes become excited and emit light of longer wavelengths. The microscope filters out the UV light and passes the emitted light through to view fluorescent specimens. Applications include using fluorescent dyes to tag and identify microbes, parasites, and antigens or antibodies in immunofluorescence techniques.
The document discusses fluorescence microscopy and fluorescent proteins. It describes how fluorescence microscopy works using light sources like mercury lamps and filters to excite and detect fluorescence. Common fluorescent proteins discussed include GFP, DsRed, and their variants. GFP derives its fluorescence from internal cyclization reactions forming a chromophore, and it and its variants are widely used as biological markers and reporters of gene expression. DsRed fluorescence comes from similar reactions and it and its variants emit light across the visible spectrum, enabling multi-color labeling experiments.
A fluorescence microscope uses fluorescence to enhance its capabilities beyond a regular light microscope. It illuminates samples tagged with fluorescent dyes with high-energy light, which causes the dyes to emit lower-energy light, producing a magnified image. This allows visualization of cell structures and live/dead cell assays. Advanced fluorescence microscopes like confocal microscopes can generate high-resolution 3D images of sample depths using lasers and image reconstruction software. Key applications include imaging cellular components, viability studies, and fluorescence in situ hybridization.
This document summarizes fluorescence microscopy. It discusses how fluorescence microscopy uses fluorescence and phosphorescence instead of reflection and absorption to study organic and inorganic substances. It describes how fluorescent dyes are used to stain cellular components, and how excitation light is absorbed by the dyes and emitted at a longer wavelength. The instrumentation of a fluorescence microscope includes fluorescent dyes, a light source, excitation and emission filters, and a dichromic mirror. Applications include identifying structures in biological samples and live cell imaging.
The document discusses fluorescence microscopy. It describes how fluorescence microscopy uses fluorescent dyes and fluorophores to stain cellular components and structures, which are then excited by light and emit light of a longer wavelength, allowing their visualization. The key parts of a fluorescence microscope are described, including the light source, excitation and emission filters, and dichroic mirror. Applications include identifying structures in fixed and live samples, and advantages are its ability to specifically label proteins and track multiple molecules simultaneously.
This document discusses confocal microscopy, which is a non-invasive imaging technique that allows for in vivo examination of the cornea at a cellular level. It describes the clinical uses of confocal microscopy in observing corneal layers, detecting diseases, and monitoring treatments. Four types of confocal microscopes are presented, including the Confoscan 4, which combines confocal microscopy with pachymetry and endothelial examination. The optical principles and anatomy of the five layers of the cornea are also outlined. Confocal microscopy provides high resolution images of normal corneal structures and changes associated with disease.
The document discusses various types of microscopes. It describes light microscopes like compound microscopes which use lenses and light to magnify specimens, and electron microscopes like transmission electron microscopes and scanning electron microscopes which use electron beams. It also mentions phase contrast microscopes which view live samples without staining, and fluorescent microscopes which use fluorescent dyes and specific wavelengths of light. The key components and working principles of these different microscope types are outlined.
The document discusses quantum mechanics and its applications. It describes how Michael Levitt and Arieh Warshel's model combining quantum and classical physics dramatically sped up calculations of protein folding while maintaining accuracy. The document also outlines a lab procedure to determine the wavelength of a laser by shining it on a surface and measuring the spacing of bands that result from splitting the laser beam with a wire.
Nobel prize in Chemistry - 2015 (Background)Ashok Kumar
Each day our DNA is damaged by UV radiation, free radicals and other carcinogenic substances, but even without such external attacks, a DNA molecule is inherently unstable. Thousands of spontaneous changes to a cell’s genome occur on a daily basis. Furthermore, defects can also arise when DNA is copied during cell division, a process that occurs several million times every day in the human body.
The reason our genetic material does not disintegrate into complete chemical chaos is that a host of molecular systems continuously monitor and repair DNA. The Nobel Prize in Chemistry 2015 awards three pioneering scientists who have mapped how several of these repair systems function at a detailed molecular level.
In the early 1970s, scientists believed that DNA was an extremely stable molecule, but Tomas Lindahl demonstrated that DNA decays at a rate that ought to have made the development of life on Earth impossible. This insight led him to discover a molecular machinery, base excision repair, which constantly counteracts the collapse of our DNA.
Aziz Sancar has mapped nucleotide excision repair, the mechanism that cells use to repair UV damage to DNA. People born with defects in this repair system will develop skin cancer if they are exposed to sunlight. The cell also utilises nucleotide excision repair to correct defects caused by mutagenic substances, among other things.
Paul Modrich has demonstrated how the cell corrects errors that occur when DNA is replicated during cell division. This mechanism, mismatch repair, reduces the error frequency during DNA replication by about a thousandfold. Congenital defects in mismatch repair are known, for example, to cause a hereditary variant of colon cancer.
The Nobel Laureates in Chemistry 2015 have provided fundamental insights into how cells function, knowledge that can be used, for instance, in the development of new cancer treatments.
Novel color photography using a high-effi ciencyprobe can super-focus white l...Janique Goff Madison
Scientists have developed new materials for next-generation electronics so tiny that they are notonly indistinguishable when closely packed, but they also don't refl ect enough light to show fi nedetails, such as colors, with even the most powerful optical microscopes. Under an opticalmicroscope, carbon nanotubes, for example, look grayish. The inability to distinguish fi ne detailsand differences between individual pieces of nanomaterials makes it hard for scientists to studytheir unique properties and discover ways to perfect them for industrial use.
its about the microscopes types and there significance in the world for diagnostic purposes .advantages and disadvantages of the types of different microscopes
Laporan Praktikum Biologi Dasar - How to use the microscopeWiwi Pratiwie
The document provides instructions for using a microscope correctly and safely. It was a report from a biology practicum conducted by Nur Pratiwi. The practicum taught students how to use microscopes to observe the smallest structures of organisms. It covered preparing the microscope, controlling the light, adjusting the lens distance, making simple microscope slides, and changing magnifications. The goal was for students to learn proper microscope procedures.
Fluorescence microscope by Subhankar DasSubhankar Das
Fluorescence microscopy uses fluorescence from organic or inorganic dyes to visualize structures within cells or tissues. It provides high resolution and contrast compared to traditional microscopy. The microscope uses a mercury lamp light source and filters to excite fluorescent dyes, which then emit light of longer wavelengths. Common fluorescent dyes include fluorescein and rhodamine. Immunfluorescence microscopy labels structures with fluorescent antibody conjugates. Photobleaching limits fluorescence over time due to excited dye molecules interacting with oxygen before emission.
The document discusses electron microscopes. It begins by explaining that Ernst Ruska built the first electron microscope in 1931 using a beam of accelerated electrons for illumination. It then describes the key components of an electron microscope, including the electron gun, condenser lenses, specimen holder, and viewing system. Electron microscopes use electromagnetic lenses and have very high magnification and resolution, allowing observation at the nanoscale. However, specimens must be dried and ultra-thin to be viewed. Electron microscopes are used widely in science and industry.
- The document discusses the discovery of cells and the development of the cell theory. It describes how early microscopes allowed scientists like Robert Hooke and Anton van Leeuwenhoek to first observe cells. The cell theory states that all living things are made of cells, cells are the basic unit of structure and function, and new cells are produced from existing cells.
- The document then explains different types of microscopes like light microscopes, fluorescence microscopes, transmission electron microscopes, and scanning electron microscopes that have allowed scientists to study cells at different levels of magnification.
- The final sections describe the differences between prokaryotic and eukaryotic cells, noting that prokaryotes lack nuclei while
The document summarizes the history and components of the confocal microscope. It describes how the confocal microscope was initially conceived in the 1950s but lacked the necessary light sources and computing power. Work in the late 1960s adapted the original concept and allowed for the examination of unstained brain and ganglion cells. Further developments in lasers and computing through the 1980s led to more practical confocal microscopes. Modern confocal microscopes integrate optics, detectors, computers and lasers to produce high-resolution 3D electronic images of samples. Confocal microscopes are now used across various fields including biology and medicine.
Fluorescence microscopy uses fluorescent dyes and high intensity light to illuminate stained samples, which emit light of a longer wavelength. The image is based on this emitted light rather than the illuminating light. Key components include a light source, excitation and emission filters, and a dichroic mirror to separate the excitation and emission wavelengths. Fluorescence microscopy is widely used in biological research to identify structures, label cellular components, and study dynamic behaviors through live-cell imaging.
Fluorescence microscopy uses fluorescent dyes and ultraviolet light to study samples. When exposed to UV light, the dyes become excited and emit light of longer wavelengths. The microscope filters out the UV light and passes the emitted light through to view fluorescent specimens. Applications include using fluorescent dyes to tag and identify microbes, parasites, and antigens or antibodies in immunofluorescence techniques.
The document discusses fluorescence microscopy and fluorescent proteins. It describes how fluorescence microscopy works using light sources like mercury lamps and filters to excite and detect fluorescence. Common fluorescent proteins discussed include GFP, DsRed, and their variants. GFP derives its fluorescence from internal cyclization reactions forming a chromophore, and it and its variants are widely used as biological markers and reporters of gene expression. DsRed fluorescence comes from similar reactions and it and its variants emit light across the visible spectrum, enabling multi-color labeling experiments.
A fluorescence microscope uses fluorescence to enhance its capabilities beyond a regular light microscope. It illuminates samples tagged with fluorescent dyes with high-energy light, which causes the dyes to emit lower-energy light, producing a magnified image. This allows visualization of cell structures and live/dead cell assays. Advanced fluorescence microscopes like confocal microscopes can generate high-resolution 3D images of sample depths using lasers and image reconstruction software. Key applications include imaging cellular components, viability studies, and fluorescence in situ hybridization.
This document summarizes fluorescence microscopy. It discusses how fluorescence microscopy uses fluorescence and phosphorescence instead of reflection and absorption to study organic and inorganic substances. It describes how fluorescent dyes are used to stain cellular components, and how excitation light is absorbed by the dyes and emitted at a longer wavelength. The instrumentation of a fluorescence microscope includes fluorescent dyes, a light source, excitation and emission filters, and a dichromic mirror. Applications include identifying structures in biological samples and live cell imaging.
The document discusses fluorescence microscopy. It describes how fluorescence microscopy uses fluorescent dyes and fluorophores to stain cellular components and structures, which are then excited by light and emit light of a longer wavelength, allowing their visualization. The key parts of a fluorescence microscope are described, including the light source, excitation and emission filters, and dichroic mirror. Applications include identifying structures in fixed and live samples, and advantages are its ability to specifically label proteins and track multiple molecules simultaneously.
This document discusses confocal microscopy, which is a non-invasive imaging technique that allows for in vivo examination of the cornea at a cellular level. It describes the clinical uses of confocal microscopy in observing corneal layers, detecting diseases, and monitoring treatments. Four types of confocal microscopes are presented, including the Confoscan 4, which combines confocal microscopy with pachymetry and endothelial examination. The optical principles and anatomy of the five layers of the cornea are also outlined. Confocal microscopy provides high resolution images of normal corneal structures and changes associated with disease.
The document discusses various types of microscopes. It describes light microscopes like compound microscopes which use lenses and light to magnify specimens, and electron microscopes like transmission electron microscopes and scanning electron microscopes which use electron beams. It also mentions phase contrast microscopes which view live samples without staining, and fluorescent microscopes which use fluorescent dyes and specific wavelengths of light. The key components and working principles of these different microscope types are outlined.
The document discusses quantum mechanics and its applications. It describes how Michael Levitt and Arieh Warshel's model combining quantum and classical physics dramatically sped up calculations of protein folding while maintaining accuracy. The document also outlines a lab procedure to determine the wavelength of a laser by shining it on a surface and measuring the spacing of bands that result from splitting the laser beam with a wire.
Nobel prize in Chemistry - 2015 (Background)Ashok Kumar
Each day our DNA is damaged by UV radiation, free radicals and other carcinogenic substances, but even without such external attacks, a DNA molecule is inherently unstable. Thousands of spontaneous changes to a cell’s genome occur on a daily basis. Furthermore, defects can also arise when DNA is copied during cell division, a process that occurs several million times every day in the human body.
The reason our genetic material does not disintegrate into complete chemical chaos is that a host of molecular systems continuously monitor and repair DNA. The Nobel Prize in Chemistry 2015 awards three pioneering scientists who have mapped how several of these repair systems function at a detailed molecular level.
In the early 1970s, scientists believed that DNA was an extremely stable molecule, but Tomas Lindahl demonstrated that DNA decays at a rate that ought to have made the development of life on Earth impossible. This insight led him to discover a molecular machinery, base excision repair, which constantly counteracts the collapse of our DNA.
Aziz Sancar has mapped nucleotide excision repair, the mechanism that cells use to repair UV damage to DNA. People born with defects in this repair system will develop skin cancer if they are exposed to sunlight. The cell also utilises nucleotide excision repair to correct defects caused by mutagenic substances, among other things.
Paul Modrich has demonstrated how the cell corrects errors that occur when DNA is replicated during cell division. This mechanism, mismatch repair, reduces the error frequency during DNA replication by about a thousandfold. Congenital defects in mismatch repair are known, for example, to cause a hereditary variant of colon cancer.
The Nobel Laureates in Chemistry 2015 have provided fundamental insights into how cells function, knowledge that can be used, for instance, in the development of new cancer treatments.
The document summarizes Nobel Prizes in Chemistry from 1989 to 1980, listing each year's recipients, their share of the prize, and a brief description of their award-winning work. It describes Sidney Altman and Thomas Cech receiving half shares in 1989 for discovering catalytic properties of RNA, and lists other recipients and achievements in subsequent years related to photosynthesis, molecular interactions, reaction dynamics, crystal structure determination, solid-state synthesis, electron transfer mechanisms, crystallographic microscopy of nucleic acid-protein complexes, and theories of chemical reactions.
1. The document discusses the biosynthesis of steroid hormones from cholesterol. Key enzymes and reactions involved in the production of pregnenolone, progesterone, cortisol, aldosterone, testosterone and other steroid hormones are described.
2. Steroid hormones are synthesized from cholesterol through a series of reactions that involve the removal of carbon side chains and addition of functional groups like hydroxyl groups.
3. Enzymes like HMG-CoA reductase and P-450SCC play important roles in initiating and regulating steroid hormone synthesis from cholesterol.
This document discusses theoretical perspectives from chemistry to explain why deep learning works. It outlines analogies between deep learning models and concepts from statistical physics such as spin glasses, the random energy model (REM), and energy landscapes. Temperature is described as a proxy for constraints on network weights. The glass transition and dynamics on energy landscapes are also discussed, as well as minimizing frustration in spin glasses and the idea of a "funneled" energy landscape with few local minima.
The Nobel Prize is an annual international award bestowed in several categories by the Nobel Foundation for achievements in physics, chemistry, physiology or medicine, literature, and peace. The prizes are presented in Stockholm, except for the Peace Prize, which is presented in Oslo. Alfred Nobel established the prizes through his will to recognize individuals "who, during the preceding year, shall have conferred the greatest benefit on mankind."
The document lists all chemistry Nobel Laureates from 1901 to 2010. It provides the names of each year's laureate(s) and a brief description of their award-winning work. Some major achievements mentioned include discoveries relating to protein structure, organic synthesis methods, electron transfer reactions, and catalytic properties of RNA and enzymes.
The document summarizes the development of cryo-electron microscopy (cryo-EM) which allows researchers to generate 3D images of biomolecules like proteins at atomic resolution. Richard Henderson, Joachim Frank, and Jacques Dubochet made key contributions to cryo-EM's development. Henderson produced the first high resolution cryo-EM image in 1990. Frank developed methods to process 2D cryo-EM images into 3D models. Dubochet invented a vitrification technique to rapidly freeze samples without damaging them. Together, their work has revolutionized structural biology by enabling atomic level views of biomolecules and their functions.
The document discusses the history of the microscope from its origins in ancient Rome to modern developments. It notes that while the Romans were the first to observe magnification using glass, the microscope was more fully developed in the late 16th/early 17th centuries by Dutch lens grinders Jansen and Van Leeuwenhoek. Key developments included compound microscopes with multiple lenses, improved magnification from 50x to 270x, and biological discoveries using microscopes. The document outlines the timeline of microscope history and classifications of microscopes based on optics, structure, application, and more modern developments like electron microscopes.
Eric Betzig, Stefan W. Hell and William E. Moerner have won the 2014 Nobel Prize in Chemistry for developing super-resolution fluorescence microscopy techniques that allow visualization of structures smaller than the diffraction limit of light. Their groundbreaking work circumvented the long-held belief that optical microscopy could not achieve resolutions better than half the wavelength of light. Using fluorescent molecules and techniques like STED and single-molecule microscopy, they made it possible to see structures at the nanoscale and observe processes inside living cells.
- Exam lanes are comprehensive sites where eye exams are conducted, including various tools to diagnose conditions and prescribe corrective lenses.
- They have evolved from simple exam rooms to include automated equipment to improve ergonomics and efficiency.
- An efficient exam lane is compact, with optimized space and layout so professionals can easily access needed tools. This saves time and reduces physical strain compared to older manual setups.
- Newer exam lanes are designed based on ergonomic principles to minimize discomfort and risk of injury from poor posture or excessive stretching during long exams.
A. The development of the has allowed us to study cells and their pro.pdfthangarajarivukadal
A. The development of the has allowed us to study cells and their processes 1. T a. Resolution is
the ability ofamicroscope to show two objects as separate Magnification is how much larger an
object appears compared to its actual size a Light microscopes are the kind we use in lab. They
function by having visible light pass through an object, and then glass lenses enlarge the object.
b. Electron microscopes use beams of electrons. They have better resolving and magnification
capabilities that allow us to see organelles and their parts. 3. Cell Theory states that all living
things & come from other cells. This theory developed as a result of contributions of 5 people
van Leeuwenhoek- 1 microscope in the 17 century b. Robert Hooke was the first person to use
the term cell to describe the basic structure of living organisms. When observing cork he noticed
that it was full of small room like structures. These structures resembled the cells that monks
lived in thus he coined the term cell in relationship Schleiden-plants are composed ofcells to
living organisms. d Schwann-animals are composed of cells e. Virchow-cells don\'t just appear
they come from preexisting cells. B. Two major classes of cells. which is coiled in region where
the nuc leus would be if the cell had a nucleus. This group includes the archaea and bacteria have
a true nucleus which is bordered by a double membrane called the nuclear enve lop. This group
includes the protists, fungi, plants, and animals collectively known as the Eukarya.
Characteristics of eukaryot ic cells A. Cytoplasm is the space in a cell between the It contains
organelles within a fluid called B. Membrane Structure and Function 1. The serves as the border
of the cell. Its unique structure allows it to regulate what enters and exits a cell, for this reason it
is oft called the gate keeper 2. Membrane Structure pecialized lipids known as make up most of
the membrane. These structures have a or water loving head that is made of a phosphate group
and two x I N
Solution
1. Developmet of microscope enabled the study of cells. Microscopes are two types light or
compound microscope and electronic microscope.
2. In a compound light microscope the high power objective lens comes close to the specimen to
magnify the image. Transmission electron microscopy (TEM) depends on the electron beam of
short wavelength to illuminate the internal structures of microorganisms. The electron beam
penetrates into the specimen and magnifies 1nm object up to 500,000X. In scanning electron
microscopy (SEM) the specimen is coated with a thin layer of heavy metal like gold or
palladium. The narrow beam of electrons probe back and forth of the metal coated specimen.
The secondary electrons that are scattered back give the image of the specimen which is
displayed on the screen.
3. According to cell theory living things are composed of one or more cells. Anton von
Leeuwenhoek (1632-1723) is considered as “Father of Microbiology”. He was the f.
The 2022 Nobel Prize in Physics was awarded to Alain Aspect, John Clauser, and Anton Zeilinger for their groundbreaking experimental work on quantum entanglement and violations of Bell's inequalities. John Clauser performed the first conclusive experiment in 1972 showing violations of Bell's inequalities. Alain Aspect then designed experiments in the 1980s enforcing stricter locality conditions. Anton Zeilinger demonstrated quantum teleportation in 1997 and performed another key Bell violation experiment in 1998. Together, their work confirmed the predictions of quantum mechanics and ruled out local hidden variable theories, resolving a decades-long debate between Einstein and Bohr. This established the foundations for the rapidly growing field of quantum information science.
Electron Microscope. This booklet is a primer on electron and ion beam microscopy and is intended for students and others interested in learning more about the history, technology, and instruments behind this fascinating field of
scientific inquiry.
Major scientific events in europe between 1945 and 1968 PortugalYeh Portugal
The document summarizes several major scientific events in Europe between 1945 and 1968, including:
1) In 1949, Egas Moniz received the Nobel Prize for developing the lobotomy procedure, though it was later banned due to serious side effects.
2) In 1948, Paul Hermann Müller received the Nobel Prize for discovering DDT's insecticidal properties, though its usage was later banned for environmental and health concerns.
3) In 1953, Hans Adolf Krebs received the Nobel Prize for identifying the Krebs cycle, which generates energy in cells.
4) In 1953, Frits Zernike received the Nobel Prize for inventing phase-contrast microscopy, allowing study of cell structures without staining
x ray spectroscopy has leading role in defining the internal structure of substances , e.g. crystal structure of compounds , elemental composition, fluorescent compounds and many more.
radiation physics is important to know for dental student to be able to utlize xray and to know the benefita and overcome the hazards of radiation. in this lecture history of discovery of xray and properties of xrays and properties of elecromagnetic waves. mechanism of xay production and parts of ddental xray machine morreover the factors affecting image quality is also discussed in details . diagrams and images are included for verification
The document discusses nanotechnology and its applications. It begins with definitions of nanotechnology as the study and use of structures between 1 and 100 nanometers in size. It then describes several methods for characterizing and synthesizing nanocrystals, including physical methods like inert gas condensation and chemical methods like metal nanocrystal synthesis via reduction. Finally, it outlines some applications of nanotechnology such as in medicine, biotechnology, energy, and industry.
Quantum theory describes the behavior of small particles like electrons and photons. It seems counterintuitive because particles can act like waves and exist in multiple states at once until observed. The theory was developed between 1900-1930 and helped establish modern physics. It includes ideas like wave-particle duality, Heisenberg's uncertainty principle, and quantum fluctuations that allow particles to briefly exist from nothing. While still incomplete, quantum theory is well-supported by evidence and critical to technologies like computers.
Lasers in oral & maxillofacial surgery/oral surgery courses by indian dental ...Indian dental academy
This document provides an overview of lasers used in oral and maxillofacial surgery. It discusses the history of lasers, laser physics including population inversion and stimulated emission, laser design components, methods of laser light delivery including articulated arms and optical fibers, laser focusing modes, and different types of lasers including CO2, Nd:YAG, and argon lasers. The key properties and applications of each laser type are described.
Indian Dental Academy: will be one of the most relevant and exciting training center with best faculty and flexible training programs for dental professionals who wish to advance in their dental practice,Offers certified courses in Dental implants,Orthodontics,Endodontics,Cosmetic Dentistry, Prosthetic Dentistry, Periodontics and General Dentistry.
This document discusses the history and development of nanotechnology. It describes how the field originated from Feynman's 1959 talk where he first proposed the concept of nanotechnology. It then discusses how the term was introduced by Professor Taniguchi in 1974 and promoted by Dr. K. Eric Drexler in the 1980s. The development of cluster science and the scanning tunneling microscope in the 1980s helped mature the field. The document outlines several applications of nanotechnology in areas like medicine, materials science, and engineering.
The document discusses the history and applications of radioisotopes and nuclear medicine. It describes how radioisotopes were discovered in the late 19th century by scientists like Roentgen, Becquerel, and the Curies. It then explains what radioisotopes are and how their atomic structure differs from stable isotopes. Finally, it summarizes some key applications of radioisotopes in medicine, including diagnostic imaging techniques like PET scans and gamma scanning that use radioactive tracers to examine organ function and identify health issues.
Biology (don't know what to name the title )MissCat403
The document discusses cells and microscopes. It summarizes that cells are the basic units of life and microscopes allow us to study cells. There are two main types of microscopes - compound microscopes, which use two lenses and are used in schools, and electron microscopes, which do not use lenses and can study extremely small objects. The discovery of cells took a long time because early scientists did not have powerful microscopes to observe cells directly.
The document summarizes key developments in cell theory from 1665 to 1880. Robert Hooke first observed cells in 1665 and they were named after rooms in cathedrals. In 1839, Schleiden and Schwann developed cell theory, stating that all living things are composed of cells. Rudolf Virchow later extended this in 1855 by proposing that all cells come from pre-existing cells, known as the biogenic law. This challenged the idea of spontaneous generation. By 1880, Weissman introduced the idea that present-day cells can trace their ancestry back to early ancestral cells.
The document discusses the nature of light and modern theories of light. It covers the following key points:
1. Historical theories including Newton's corpuscular theory proposing light is particles and Huygens' wave theory proposing light is waves.
2. Modern theories including Maxwell's electromagnetic theory showing light is electromagnetic waves, Planck and Einstein's quantum theory proposing light consists of discrete quanta called photons, and de Broglie's wave-particle duality theory showing light has both wave and particle properties.
3. The document analyzes the successes and failures of each theory and how later theories built upon earlier understandings to more fully explain the nature of light.
É revisitada a famosa palestra de Niels Bohr em 1932 com o mesmo título, procurando atualizála. Os tópicos tratados são: 1) Intuição biológica. 2) Avanços básicos. 3) A origem da vida.
4) Dos procariontes aos eucariontes. 5) Luz solar e a vida. 6) A física quântica é relevante para a biologia? 7) Mecânica quântica, cérebro e mente. 8) A consciência. 9) Existe livre arbítrio? 10) A luz como arma da biologia: Pinças óticas. 11) Calibração absoluta das pinças. 12) Proteínas como demônios de Maxwell. 13) A catraca browniana. 14) Proteinas motoras: cinesina, miosina V e ATPsintase. 15) Mecanobiologia. 16) Nanotubos de tunelamento. 17) Comunicação à distância entre células e suas funções. 18) “Le hasard et la nécessité”.
When I was asked to give a companion lecture in support of ‘The Philosophy of Science’ (https://shorturl.at/4pUXz) I decided not to walk through the detail of the many methodologies in order of use. Instead, I chose to employ a long standing, and ongoing, scientific development as an exemplar. And so, I chose the ever evolving story of Thermodynamics as a scientific investigation at its best.
Conducted over a period of >200 years, Thermodynamics R&D, and application, benefitted from the highest levels of professionalism, collaboration, and technical thoroughness. New layers of application, methodology, and practice were made possible by the progressive advance of technology. In turn, this has seen measurement and modelling accuracy continually improved at a micro and macro level.
Perhaps most importantly, Thermodynamics rapidly became a primary tool in the advance of applied science/engineering/technology, spanning micro-tech, to aerospace and cosmology. I can think of no better a story to illustrate the breadth of scientific methodologies and applications at their best.
hematic appreciation test is a psychological assessment tool used to measure an individual's appreciation and understanding of specific themes or topics. This test helps to evaluate an individual's ability to connect different ideas and concepts within a given theme, as well as their overall comprehension and interpretation skills. The results of the test can provide valuable insights into an individual's cognitive abilities, creativity, and critical thinking skills
Unlocking the mysteries of reproduction: Exploring fecundity and gonadosomati...AbdullaAlAsif1
The pygmy halfbeak Dermogenys colletei, is known for its viviparous nature, this presents an intriguing case of relatively low fecundity, raising questions about potential compensatory reproductive strategies employed by this species. Our study delves into the examination of fecundity and the Gonadosomatic Index (GSI) in the Pygmy Halfbeak, D. colletei (Meisner, 2001), an intriguing viviparous fish indigenous to Sarawak, Borneo. We hypothesize that the Pygmy halfbeak, D. colletei, may exhibit unique reproductive adaptations to offset its low fecundity, thus enhancing its survival and fitness. To address this, we conducted a comprehensive study utilizing 28 mature female specimens of D. colletei, carefully measuring fecundity and GSI to shed light on the reproductive adaptations of this species. Our findings reveal that D. colletei indeed exhibits low fecundity, with a mean of 16.76 ± 2.01, and a mean GSI of 12.83 ± 1.27, providing crucial insights into the reproductive mechanisms at play in this species. These results underscore the existence of unique reproductive strategies in D. colletei, enabling its adaptation and persistence in Borneo's diverse aquatic ecosystems, and call for further ecological research to elucidate these mechanisms. This study lends to a better understanding of viviparous fish in Borneo and contributes to the broader field of aquatic ecology, enhancing our knowledge of species adaptations to unique ecological challenges.
Describing and Interpreting an Immersive Learning Case with the Immersion Cub...Leonel Morgado
Current descriptions of immersive learning cases are often difficult or impossible to compare. This is due to a myriad of different options on what details to include, which aspects are relevant, and on the descriptive approaches employed. Also, these aspects often combine very specific details with more general guidelines or indicate intents and rationales without clarifying their implementation. In this paper we provide a method to describe immersive learning cases that is structured to enable comparisons, yet flexible enough to allow researchers and practitioners to decide which aspects to include. This method leverages a taxonomy that classifies educational aspects at three levels (uses, practices, and strategies) and then utilizes two frameworks, the Immersive Learning Brain and the Immersion Cube, to enable a structured description and interpretation of immersive learning cases. The method is then demonstrated on a published immersive learning case on training for wind turbine maintenance using virtual reality. Applying the method results in a structured artifact, the Immersive Learning Case Sheet, that tags the case with its proximal uses, practices, and strategies, and refines the free text case description to ensure that matching details are included. This contribution is thus a case description method in support of future comparative research of immersive learning cases. We then discuss how the resulting description and interpretation can be leveraged to change immersion learning cases, by enriching them (considering low-effort changes or additions) or innovating (exploring more challenging avenues of transformation). The method holds significant promise to support better-grounded research in immersive learning.
The cost of acquiring information by natural selectionCarl Bergstrom
This is a short talk that I gave at the Banff International Research Station workshop on Modeling and Theory in Population Biology. The idea is to try to understand how the burden of natural selection relates to the amount of information that selection puts into the genome.
It's based on the first part of this research paper:
The cost of information acquisition by natural selection
Ryan Seamus McGee, Olivia Kosterlitz, Artem Kaznatcheev, Benjamin Kerr, Carl T. Bergstrom
bioRxiv 2022.07.02.498577; doi: https://doi.org/10.1101/2022.07.02.498577
The debris of the ‘last major merger’ is dynamically youngSérgio Sacani
The Milky Way’s (MW) inner stellar halo contains an [Fe/H]-rich component with highly eccentric orbits, often referred to as the
‘last major merger.’ Hypotheses for the origin of this component include Gaia-Sausage/Enceladus (GSE), where the progenitor
collided with the MW proto-disc 8–11 Gyr ago, and the Virgo Radial Merger (VRM), where the progenitor collided with the
MW disc within the last 3 Gyr. These two scenarios make different predictions about observable structure in local phase space,
because the morphology of debris depends on how long it has had to phase mix. The recently identified phase-space folds in Gaia
DR3 have positive caustic velocities, making them fundamentally different than the phase-mixed chevrons found in simulations
at late times. Roughly 20 per cent of the stars in the prograde local stellar halo are associated with the observed caustics. Based
on a simple phase-mixing model, the observed number of caustics are consistent with a merger that occurred 1–2 Gyr ago.
We also compare the observed phase-space distribution to FIRE-2 Latte simulations of GSE-like mergers, using a quantitative
measurement of phase mixing (2D causticality). The observed local phase-space distribution best matches the simulated data
1–2 Gyr after collision, and certainly not later than 3 Gyr. This is further evidence that the progenitor of the ‘last major merger’
did not collide with the MW proto-disc at early times, as is thought for the GSE, but instead collided with the MW disc within
the last few Gyr, consistent with the body of work surrounding the VRM.
ESA/ACT Science Coffee: Diego Blas - Gravitational wave detection with orbita...Advanced-Concepts-Team
Presentation in the Science Coffee of the Advanced Concepts Team of the European Space Agency on the 07.06.2024.
Speaker: Diego Blas (IFAE/ICREA)
Title: Gravitational wave detection with orbital motion of Moon and artificial
Abstract:
In this talk I will describe some recent ideas to find gravitational waves from supermassive black holes or of primordial origin by studying their secular effect on the orbital motion of the Moon or satellites that are laser ranged.
Phenomics assisted breeding in crop improvementIshaGoswami9
As the population is increasing and will reach about 9 billion upto 2050. Also due to climate change, it is difficult to meet the food requirement of such a large population. Facing the challenges presented by resource shortages, climate
change, and increasing global population, crop yield and quality need to be improved in a sustainable way over the coming decades. Genetic improvement by breeding is the best way to increase crop productivity. With the rapid progression of functional
genomics, an increasing number of crop genomes have been sequenced and dozens of genes influencing key agronomic traits have been identified. However, current genome sequence information has not been adequately exploited for understanding
the complex characteristics of multiple gene, owing to a lack of crop phenotypic data. Efficient, automatic, and accurate technologies and platforms that can capture phenotypic data that can
be linked to genomics information for crop improvement at all growth stages have become as important as genotyping. Thus,
high-throughput phenotyping has become the major bottleneck restricting crop breeding. Plant phenomics has been defined as the high-throughput, accurate acquisition and analysis of multi-dimensional phenotypes
during crop growing stages at the organism level, including the cell, tissue, organ, individual plant, plot, and field levels. With the rapid development of novel sensors, imaging technology,
and analysis methods, numerous infrastructure platforms have been developed for phenotyping.
The use of Nauplii and metanauplii artemia in aquaculture (brine shrimp).pptxMAGOTI ERNEST
Although Artemia has been known to man for centuries, its use as a food for the culture of larval organisms apparently began only in the 1930s, when several investigators found that it made an excellent food for newly hatched fish larvae (Litvinenko et al., 2023). As aquaculture developed in the 1960s and ‘70s, the use of Artemia also became more widespread, due both to its convenience and to its nutritional value for larval organisms (Arenas-Pardo et al., 2024). The fact that Artemia dormant cysts can be stored for long periods in cans, and then used as an off-the-shelf food requiring only 24 h of incubation makes them the most convenient, least labor-intensive, live food available for aquaculture (Sorgeloos & Roubach, 2021). The nutritional value of Artemia, especially for marine organisms, is not constant, but varies both geographically and temporally. During the last decade, however, both the causes of Artemia nutritional variability and methods to improve poorquality Artemia have been identified (Loufi et al., 2024).
Brine shrimp (Artemia spp.) are used in marine aquaculture worldwide. Annually, more than 2,000 metric tons of dry cysts are used for cultivation of fish, crustacean, and shellfish larva. Brine shrimp are important to aquaculture because newly hatched brine shrimp nauplii (larvae) provide a food source for many fish fry (Mozanzadeh et al., 2021). Culture and harvesting of brine shrimp eggs represents another aspect of the aquaculture industry. Nauplii and metanauplii of Artemia, commonly known as brine shrimp, play a crucial role in aquaculture due to their nutritional value and suitability as live feed for many aquatic species, particularly in larval stages (Sorgeloos & Roubach, 2021).
Current Ms word generated power point presentation covers major details about the micronuclei test. It's significance and assays to conduct it. It is used to detect the micronuclei formation inside the cells of nearly every multicellular organism. It's formation takes place during chromosomal sepration at metaphase.
PPT on Direct Seeded Rice presented at the three-day 'Training and Validation Workshop on Modules of Climate Smart Agriculture (CSA) Technologies in South Asia' workshop on April 22, 2024.
The binding of cosmological structures by massless topological defectsSérgio Sacani
Assuming spherical symmetry and weak field, it is shown that if one solves the Poisson equation or the Einstein field
equations sourced by a topological defect, i.e. a singularity of a very specific form, the result is a localized gravitational
field capable of driving flat rotation (i.e. Keplerian circular orbits at a constant speed for all radii) of test masses on a thin
spherical shell without any underlying mass. Moreover, a large-scale structure which exploits this solution by assembling
concentrically a number of such topological defects can establish a flat stellar or galactic rotation curve, and can also deflect
light in the same manner as an equipotential (isothermal) sphere. Thus, the need for dark matter or modified gravity theory is
mitigated, at least in part.
Remote Sensing and Computational, Evolutionary, Supercomputing, and Intellige...University of Maribor
Slides from talk:
Aleš Zamuda: Remote Sensing and Computational, Evolutionary, Supercomputing, and Intelligent Systems.
11th International Conference on Electrical, Electronics and Computer Engineering (IcETRAN), Niš, 3-6 June 2024
Inter-Society Networking Panel GRSS/MTT-S/CIS Panel Session: Promoting Connection and Cooperation
https://www.etran.rs/2024/en/home-english/
20240520 Planning a Circuit Simulator in JavaScript.pptx
Popular chemistryprize2014
1. THE NOBEL PRIZE IN CHEMISTRY 2014
POPULAR SCIENCE BACKGROUND
How the optical microscope became a nanoscope
Eric Betzig, Stefan W. Hell and William E. Moerner are awarded the Nobel Prize in Chemistry 2014
for having bypassed a presumed scientific limitation stipulating that an optical microscope can never
yield a resolution better than 0.2 micrometres. Using the fluorescence of molecules, scientists can
now monitor the interplay between individual molecules inside cells; they can observe disease-related
proteins aggregate and they can track cell division at the nanolevel.
Red blood cells, bacteria, yeast cells and spermatozoids. When scientists in the 17th century for
the first time studied living organisms under an optical microscope, a new world opened up before
their eyes. This was the birth of microbiology, and ever since, the optical microscope has been one
of the most important tools in the life-sciences toolbox. Other microscopy methods, such as electron
microscopy, require preparatory measures that eventually kill the cell.
Glowing molecules surpassing a physical limitation
For a long time, however, optical microscopy was held back by a physical restriction as to what size
of structures are possible to resolve. In 1873, the microscopist Ernst Abbe published an equation
demonstrating how microscope resolution is limited by, among other things, the wavelength of the
light. For the greater part of the 20th century this led scientists to believe that, in optical microscopes,
they would never be able to observe things smaller than roughly half the wavelength of light, i.e.,
0.2 micrometres (figure 1). The contours of some of the cells’ organelles, such as the powerhouse
mitochondria, were visible. But it was impossible to discern smaller objects and, for instance, to
follow the interaction between individual protein molecules in the cell. It is somewhat akin to being
able to see the buildings of a city without being able to discern how citizens live and go about their
lives. In order to fully understand how a cell functions, you need to be able to track the work of
individual molecules.
Abbe’s equation still holds but has been bypassed just the same. Eric Betzig, Stefan W. Hell and
William E. Moerner are awarded the Nobel Prize in Chemistry 2014 for having taken optical
microscopy into a new dimension using fluorescent molecules. Theoretically there is no longer any
structure too small to be studied. As a result, microscopy has become nanoscopy.
ABBE’S DIFFRACTION LIMIT (0.2 m)
1 mm 100m 10m 1m 100 nm 10 nm 1nm
ant hair mammalian cell bacterium mitochondrion virus protein small molecule
Nobel Prize® is a registered trademark of the Nobel Foundation.
Figure 1. At the end of the 19th century, Ernst Abbe defined the limit for optical microscope resolution to roughly half the wavelength
of light, about 0.2 micrometre. This meant that scientists could distinguish whole cells, as well as some parts of the cell called
organelles. However, they would never be able to discern something as small as a normal-sized virus or single proteins.
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THE NOBEL PRIZE IN CHEMISTRY 2014 THE ROYAL SWEDISH ACADEMY OF SCIENCES HTTP://KVA.SE
The story of how Abbe’s diffraction limit was circumvented runs in parallel tracks; two different principles are rewarded, which have been developed independently of each other. We begin in 1993, in a student apartment in South-western Finland, where Stefan Hell had a brilliant idea as he was leafing through a textbook in Quantum Optics.
Youthful revolt against Abbe’s diffraction limit met with scepticism
Ever since getting his Ph D from the University of Heidelberg in 1990, Stefan Hell had been looking for a way to bypass the limitation that Ernst Abbe had defined more than a century earlier. The thought of challenging such an established principle was tantalizing. But senior scientists in Germany had met his enthusiasm with scepticism, and hence Stefan Hell had taken refuge in the cold North. A professor at the University of Turku who was working on fluorescence microscopy had offered him a position on his research team. Hell was convinced that there had to be a way of circumventing Abbe’s diffraction limit, and when he read the words stimulated emission in the book on Quantum Optics a new line of thought took shape in his mind: “At that moment, it dawned on me. I had finally found a concrete concept to pursue – a real thread.” Such was his comment in 2009 - let us delve into his idea.
The solution: a nano-sized flashlight scanning over the sample
In Turku Stefan Hell worked on so-called fluorescence microscopy, a technique where scientists use fluorescent molecules to image parts of the cell. For instance, they can use fluorescent antibodies that couple specifically to cellular DNA. Scientists excite the antibodies with a brief light pulse, making them glow for a short while. If the antibodies couple to DNA they will radiate from the centre of the cell, where DNA is packed inside the cell nucleus. In this manner, scientists can see where a certain molecule is located. But they had only been able to locate clusters of molecules, such as entangled strands of DNA. The resolution was too low to discern individual DNA strings. Think of being able to see a roll of yarn without being able to follow the thread itself. When Stefan Hell read about stimulated emission, he realized that it should be possible to devise a kind of nano-flashlight that could sweep along the sample, a nanometre at a time. By using stimulated emission scientists can quench fluorescent molecules. They direct a laser beam at the molecules that immediately lose their energy and become dark. In 1994, Stefan Hell published an article outlining his ideas. In the proposed method, so-called stimulated emission depletion (STED), a light pulse excites all the fluorescent molecules, while another light pulse quenches fluorescence from all molecules except those in a nanometre-sized volume in the middle (figure 2). Only this volume is then registered. By sweeping along the sample and continuously measuring light levels, it is possible to get a comprehensive image. The smaller the volume allowed to fluoresce at a single moment, the higher the resolution of the final image. Hence, there is, in principle, no longer any limit to the resolution of optical microscopes.
Developing the first nano-flashlight in Germany
Stefan Hell’s theoretical article did not create any immediate commotion, but was interesting enough for Stefan Hell to be offered a position at the Max Planck Institute for Biophysical Chemistry in Göttingen. In the following years he brought his ideas to fruition; he developed a STED microscope. In 2000 he was able to demonstrate that his ideas actually work in practice, by, among other things, imaging an E. coli bacterium at a resolution never before achieved in an optical microscope (figure 3).
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THE NOBEL PRIZE IN CHEMISTRY 2014 THE ROYAL SWEDISH ACADEMY OF SCIENCES HTTP://KVA.SE
The STED microscope collects light from a multitude of small volumes to create a large whole. In contrast, the second principle rewarded, single-molecule microscopy, entails the superposition of several images. Eric Betzig and W. E. Moerner (who always has been called by his initials, W. E.) have independently of each other contributed different fundamental insights in its development. The foundation was laid when W. E. Moerner succeeded in detecting a single small fluorescent molecule.
W. E. Moerner – first to detect a single fluorescent molecule
In most chemical methods, for instance measuring absorption and fluorescence, scientists study millions of molecules simultaneously. The results of such experiments represent a kind of typical, average molecule. Scientists have had to accept this since nothing else has been possible, but for a long time they dreamt of measuring single molecules, because the richer and more detailed the knowledge, the greater the possibility to understand, for instance, how diseases develop. Therefore, in 1989, when W. E. Moerner as the first scientist in the world was able to measure the light absorption of a single molecule, it was a pivotal achievement. At the time he was working at the IBM research centre in San Jose, California. The experiment opened the door to a new future and inspired many chemists to turn their attention to single molecules. One of them was Eric Betzig, whose achievements will be covered below.
Regular optic
al microscopeSTED microscopeFigure 21In a regular optical microscope, the contours of a mitochondrion can be distinguished, but the resolution can never get better than 0.2 micrometres. In a STED microscope, an annular laser beam quenches all fluorescence except that in a nanometre-sized volume. Exciting laser beamExciting laser beamQuenching laser beamThe laser beams scan over the sample. Since scientists know exactly where the beam hits the sample, they can use that informa- tion to render the image at a much higher resolution. The final image gets a resolution that is much better than 0.2 micrometre. 223The principle of STED microscopy
Figure 3. One of the first images taken by Stefan Hell using a STED microscope. To the left, an E. coli bacterium imaged using conventional microscopy; to the right, the same bacterium imaged using STED. The resolution of the STED image is three times better. Image from Proc. Natl. Acad. Sci. USA 97: 8206–8210.
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Eight years later Moerner took the next step towards single-molecule microscopy, building on the
previously Nobel Prize-awarded discovery of the green fluorescent protein (GFP).
Molecular-sized lamps turning on and off
In 1997 W. E. Moerner had joined the University of California in San Diego, where Roger Tsien,
Nobel Prize Laureate to be, was trying to get GFP to fluoresce in all the colours of the rainbow.
The green protein was isolated from a fluorescent jelly-fish and its strength lies in its ability to make
other proteins inside living cells visible. Using gene technology scientists couple the green fluorescent
protein to other proteins. The green light subsequently reveals exactly where in the cell the marked
protein is positioned.
W. E. Moerner discovered that the fluorescence of one variant of GFP could be turned on and off
at will. When he excited the protein with light of wavelength 488 nanometres the protein began
to fluoresce, but after a while it faded. Regardless of the amount of light he then directed at the
protein, the fluorescence was dead. It turned out, however, that light of wavelength 405 nanometres
could bring the protein back to life again. When the protein was reactivated, it once again fluoresced
at 488 nanometres.
Moerner dispersed these excitable proteins in a gel, so that the distance between each individual protein
was greater than Abbe’s diffraction limit of 0.2 micrometres. Since they were sparsely scattered, a regular
optical microscope could discern the glow from individual molecules – they were like tiny lamps
with switches. The results were published in the scientific journal Nature in 1997.
By this discovery Moerner demonstrated that it is possible to optically control fluorescence of single
molecules. This solved a problem that Eric Betzig had formulated two years earlier.
Tired of the academy – but obsessed by Abbe’s diffraction limit.
Just like Stefan Hell, Eric Betzig was obsessed by the idea of bypassing Abbe’s diffraction limit. In
the beginning of the 1990s he was working on a new kind of optical microscopy called near-field
microscopy at the Bell Laboratories in New Jersey. In near-field microscopy the light ray is emitted
from an extremely thin tip placed only a few nanometres from the sample. This kind of microscopy can
also circumvent Abbe’s diffraction limit, although the method has major weaknesses. For instance,
the light emitted has such a short range that it is difficult to visualize structures below the cell surface.
In 1995 Eric Betzig concluded that near-field microscopy could not be improved much further. In
addition, he did not feel at home in academia and decided to end his research career; without knowing
where to go next, he quit Bell Labs. But Abbe’s diffraction limit remained in his mind. During a
walk a cold winter day a new idea came to him; might it be possible to circumvent the diffraction
limit by using molecules with different properties, molecules that fluoresced with different colours?
Inspired by W. E. Moerner, among others, Eric Betzig had already detected fluorescence in single
molecules using near-field microscopy. He began to ponder whether a regular microscope could yield
the same high resolution if different molecules glowed with different colours, such as red, yellow and
green. The idea was to have the microscope register one image per colour. If all molecules of one
colour were dispersed and never closer to each other than the 0.2 micrometres stipulated by Abbe’s
diffraction limit, their position could be determined very precisely. Next, when these images were
superimposed, the complete image would get a resolution far better than Abbe’s diffraction limit, and
red, yellow and green molecules would be distinguishable even if their distance was just a few nano-
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metres. In this manner Abbe’s diffraction limit could be circumvented. However, there were some
practical problems, for instance a lack of molecules with a sufficient amount of distinguishable
optical properties.
In 1995 Eric Betzig published his theoretical ideas in the journal Optics Letters, and subsequently left
academia and joined his father’s company.
Lured back to microscopy by green fluorescent proteins
For many years Eric Betzig was entirely disconnected from the research community. But one day
a longing for science sprang to life again, and returning to the scientific literature he came across
the green fluorescent protein for the first time. Realizing there was a protein that could make other
proteins visible inside cells revived Betzig’s thoughts of how to circumvent Abbe’s diffraction limit.
The real breakthrough came in 2005, when he stumbled across fluorescent proteins that could be
activated at will, similar to those that W. E. Moerner had detected in 1997 at the level of a single
molecule. Betzig realized that such a protein was the tool required to implement the idea that had
come to him ten years earlier. The fluorescent molecules did not have to be of different colours, they
could just as well fluoresce at different times.
Surpassing Abbe’s limit by superimposing images
Just one year later, Eric Betzig demonstrated, in collaboration with scientists working on excitable
fluorescent proteins, that his idea held up in practice. Among other things, the scientists coupled the
glowing protein to the membrane enveloping the lysosome, the cell’s recycling station. Using a light
pulse the proteins were activated for fluorescence, but since the pulse was so weak only a fraction of
them started to glow. Due to their small number, almost all of them were positioned at a distance
The principle of
single-molecule
microscopy
1
High-resolution
image
Single
fluorescent
protein
The distance between each protein 0.2 m
The blurred images are processed using
probability theory in order to render them
much sharper.
2
When all images are
superimposed a high
resolution totality
appears, wherein
individual proteins can
be discerned.
3
Microscope
A weak light pulse
activates a fraction of all
the fluorescent proteins.
The distance between
them is greater than
Abbe’s diffraction limit of
0.2 micrometres. They
glow until bleached, at
which point the procedure
is repeated on a new
subgroup of proteins.
Figure 4
6. 6(7) THE NOBEL PRIZE IN CHEMISTRY 2014 THE ROYAL SWEDISH ACADEMY OF SCIENCES HTTP://KVA.SE
from each other greater than Abbe’s diffraction limit of 0.2 micrometres. Hence the position of each
glowing protein could be registered very precisely in the microscope. After a while, when their fluo-rescence
died out, the scientists activated a new subgroup of proteins. Again, the pulse was so weak
that only a fraction of the proteins began to glow, whereupon another image was registered. This
procedure was then repeated over and over again.
When Betzig superimposed the images he ended up with a super-resolution image of the lysosome
membrane. Its resolution was far better than Abbe’s diffraction limit. An article published in Science
in 2006 subsequently presented the ground-breaking work.
The laureates are still mapping the innermost secrets of life
The methods developed by Eric Betzig, Stefan Hell and W. E. Moerner have led to several
nanoscopy techniques and are currently used all over the world. The three Laureates are still active
researchers in the large and growing community of scientists spearheading innovation in the field
of nanoscopy. When they direct their powerful nanoscopes toward the tiniest components of life
they also produce cutting-edge knowledge. Stefan Hell has peered inside living nerve cells in order
to better understand brain synapses. W. E. Moerner has studied proteins in relation to Huntington’s
disease. Eric Betzig has tracked cell division inside embryos. These are just a few of many examples.
One thing is certain, the Nobel Laureates in Chemistry 2014 have laid the foundation for the
development of knowledge of the greatest importance to mankind.
Figure 5. The centre image shows lysosome membranes and is one of the first ones taken by Betzig using single-molecule microscopy.
To the left, the same image taken using conventional microscopy. To the right, the image of the membranes has been enlarged. Note
the scale division of 0.2 micrometres, equivalent to Abbe’s diffraction limit. The resolution is many times improved. Image from
Science 313:1642–1645.