Monthly Archives: July 2015

UNASKED QUESTIONS ABOUT RESEARCH GRANTS FOR SCIENCE, AND MY ANSWERS!

Answers are badly needed for the many questions about research grants in science! (http://dr-monsrs.net)
Answers are badly needed for the many questions about research grants in science!      (http://dr-monsrs.net)
 

Research grants pay for all the many expenses of doing scientific research in universities, and now are the primary focus for faculty scientists.  Size and number of grants determines salary level, promotions, amount of assigned laboratory space, teaching duties required, professional status and reputation, and, ability to have graduate students working in a given lab.  Research grants typically are awarded to science faculty for 3-5 years; grant renewals are not always successful, or can be funded only partially.  Without continuing to acquire and maintain this external funding, it is basically impossible to be employed or doing research as a  university scientist in the United States.

This condition causes many secondary problems, all of which impede research progress.  In my opinion, the very worst of these is the hyper-competition for research grants (see: “All About Today’s Hyper-competition for Research Grants” ).  Every scientist  is competing with every other scientist for an award from a limited pool of money.  For university scientists, this activity consumes giant amounts of time that would and should be spent on research experiments, burns up large amounts of personal energy, distorts emotions and disturbs sleep,  causes and encourages dishonesty, and, is very frustrating whenever  applications are not successful.  I previously discussed how all this causes so many university scientists to be dissatisfied with their career (see: “Why are University Scientists Increasingly Upset with their Job?  Part I” , and, “Part II” ). 

This essay gives questions about the present research grant system that usually are not asked, and my best answers to them no matter how disturbing that might be.  I have phrased these questions just as they would be given by non-scientist readers of this website.  Everyone should know that I have reviewed grant applications as a member of several special review panels, held several research grants (for which I am very thankful!), and, also had several of my applications rejected.  Hence, my responses to these questions are based upon my own personal experiences as a faculty scientist.  

Maybe the hyper-competition actually is good!  Isn’t it true that the very best research scientists always will be funded? 

Not always!  Sometimes the “best research scientists” also get rejected, or are only partially funded; despite their status, they can get careless, arrogant, or too aged.  Nevertheless, leading scientists are favored to stay funded because  they understand exactly how the grant system works, and have easier interactions with officials at the granting agencies.  In my opinion, only indirect correlations exist between success in acquiring very many research dollars, and production of many breakthrough research results.  Excelling in either one says little about results in the other.  

Do scientists doing very good research always get funded? 

Not always!  Getting a grant or a renewal always is chancy and never is certain, since this decision involves strategy, governmental budgets, contacts with officials at the granting agencies, which side of the bed reviewers get up from, and many other non-science factors.  Young scientists spend very many years with their research training and early work as a member of some science faculty, but then can be abruptly discharged for having trouble or failing at this business task; remember that these scientists are trained to be researchers, and are not graduates of a business school!  

Don’t university scientists mainly need to get good research publications? 

The main job of university scientists today is no longer to get good publications, but rather is to acquire more research grant funds!  I doubt that science graduate students ever intend to work for over a decade to become a faculty scientist just so they can spend their professional life chasing money (see: “What is the New Main Job of Faculty Scientists Today?” ).  But, that is exactly what the hyper-competition forces them to do!  For most researchers, the hyper-competition for grants in universities badly distorts what it means to be a scientist; hence, I believe it is very bad for science. 

Aren’t scientists trained about how to deal with this research grant problem when they were graduate students or postdocs? 

There certainly are no organized sessions or courses in finance, commerce, or business given to graduate students in science, even though university science now certainly is a big business (see: “Money Now is Everything in Scientific Research at Universities” .

Isn’t there some way faculty scientists can avoid this situation? 

Yes indeed, but it ain’t so easy!  Switching to a research job in industry or to a non-research job outside universities will resolve this problem situation.  The main way  university scientists try to preclude this problem is to acquire 2 (or more!) research grants; then, if one award later is not renewed, the other one then will keep the faculty scientist’s career intact.  Of course, this strategy of seeking to acquire multiple research grants has its own costs and directly serves to make the hyper-competition even more intense. 

Why not simply require all faculty scientists to get 2 research grants?  

This idea ignores the fact that running a productive research lab in academia takes up a huge bunch of precious time.  Faculty scientists with 2 research grants usually become so short of time that they must switch gears so as to function as a research manager, rather than continue as a research scientist.  Some managers even reserve one half-day per week where they are not to be interrupted for any reason by anyone while they work in their own lab.  Another fact to be recognized is that most university scientists today do not ever hold 2 concurrent research grants. 

Isn’t there counselling and help given to faculty members who lose their grant? 

At some universities this now is done, thank goodness!  However, at many others, the affected professionals must try to get funded again all by themselves.  It is a sign of the vicious nature of the hyper-competition for research grants that any scientists who try to help a fellow faculty colleague (i.e., a competitor) necessarily are also hurting themselves.

Cannot some research experiments be done without a grant?  

This could be done, but it is not permitted!  Upon rejection of an application for renewal, faculty scientists soon lose their assigned laboratory space, thus precluding any more experiments; at some institutions, each then is viewed as a “loser” and is suspected of being a “failed scientist”.  I consider this system of “feast or famine” to be horribly ridiculous; nevertheless, it does show loud and clear what is the true end of scientific research in modern universities (see: “What is the New Main Job of Faculty Scientists Today?”). 

Is there some other way to support science without causing such difficult problems? 

This is theoretically possible, but in practice it is nearly impossible because the present research grant system is so deeply entrenched.  There is a very large activation barrier to making any changes since universities and leaders at the granting agencies both are very happy with the status quo (i.e., universities get good profits from the research grants of their science faculty, and research grant agencies receive an increasing number of applications for financial support).  Although this question is discussed in private by university scientists, I am not aware of any open general discussions about trying out some alternative approaches to support research activities in science. 

If the research grant system really is so troubled and has such awful effects, why don’t all the university scientists protest? 

Every university scientist holding a research grant knows better than to complain about being a slave in the modern research grant system, because they want to continue being funded.  As the saying goes, “Do not bite the hand that feeds you”! 

My comments and conclusions. 

I see the present problems with the research grant system as being very unfortunate for science.  The current situation has bad effects on research progress and clearly is very vicious to some scientists.  This system is  strongly supported by both all universities and the granting agencies.  Any proposals to make any changes will be strongly opposed by all the beneficiaries of this system, including funded scientists working at universities. 

My main conclusions are that (1) business and money now rule science, and (2) everything about scientific research at universities now is money (see: “Introduction to Money in Modern Scientific Research” , and, “3 Money Cycles Support Scientific Research” ).  I  certainly am not the only one to reach these conclusions (i.e., search for “money in science” on any internet browser, and you will see what I mean!). 

Quality of experimental research, creative ideas for experiments, derivation of innovative concepts, and working hard with a difficult project are no longer very important.  All that matters now is to get the money!  All these negatives form a strong basis for why I regretfully believe that science now is dying (see: “Could Science and Research Now be Dying?” ). 

 

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MICROSCOPY FOR EDUCATION, SCIENTIFIC RESEARCH, AND FUN! PART 4: MICROSCOPY FOR EARLY SCIENCE EDUCATION.

 

Different kinds of microscopy present a wealth of information.    ( http://dr-monsrs.net )
Different kinds of microscopy present a wealth of info!  ( http://dr-monsrs.net )

 

Few research instruments are as widely used in science as are microscopes.  They are very extensively utilized in universities, industries, hospitals, specialized assay services, forensic labs, mineralogy, crystallography, etc.  Microscopes and microscopy recently have become more available and more adapted for science education, beginning in primary (elementary, grade) schools.  For those of us working with microscopes, they not only let us do our specialized job in scientific research, but also provide quite a lot of fun.

The fundamental concepts and terms for using microscopes and understanding microscopy in general (see: “Part 1” ), and, light microscopy (see: “Part 2” ) and electron microscopy (see: “Part 3” ) in particular, have been covered previously.  This fourth article gives my views about the value of microscopy for teaching science in primary and secondary (middle, high) schools.  Beginners reading Part 4 should first study Part 1.

Why is microscopy really, really good for early science education? 

I believe that early science education is not only essential for future scientists, but also is badly needed for everyone else.  I am especially enthusiastic about using microscopy for science education in primary schools, since it:  (1)  features hands-on learning, (2) is not selective for any one branch of science, (3) involves doing, seeing, thinking, questioning, and discussing, (4) can be open-ended since the young students will utilize their native curiosity to look at additional specimens of their own choice, and (5) raises early interest in some students for becoming a scientist.  Addition of hands-on microscopy to primary and secondary school science classes  will make them wonderfully better than the traditional science teaching that emphasizes memorizing facts and figures.  That old approach neither elicits student enthusiasm and individual interest in science, nor prepares students to live in a modern world that is dominated by new and changing  technology.  Education with microscopy is education in science and technology.

Microscopy for science education: what will actually be learned? 

In addition to learning how to operate light microscopes, young students will relate this to many other areas of knowledge and activity.  Coursework with microscopy teaches at 2 distinct levels: direct  knowledge, and indirect knowledge.  Direct knowledge covers essentials in optics, design and features of different microscopes, specimen preparation, imaging, and measuring.  Microscopy in secondary schools should include introductory instruction about electron microscopes, crystallography and diffraction, and, spectroscopy.  Indirect knowledge is given when an image from microscopy is shown to illustrate a didactic subject in some other course (e.g., flowers or minerals, disease bacteria or viruses, the human eye, biofilms, LEDs, solid state computer devices, normal and cancer cells, polymers, etc.).  Understanding microscopy thus helps students to learn about many other subjects.  Specimens selected for classroom use always should include some objects already familiar to students, and, be coordinated with concurrent other courses.

What does microscopy do for science education that books and videos do not do? 

For young students in primary school, looking is not enough!  They must learn to see (e.g., substructure which is not visible to the naked eye), to think (e.g., why do we not always look at specimens only with the highest magnification lens?), to discuss (e.g., how can the diameter of human hairs best be measured?), and to ask questions.   For learning, classes using  microscopes have at least 7 major advantages over reading textbooks:

1.  microscopy is a hands-on activity;

2.  microscopy simultaneously involves activity by the eyes, hands, and brain;

3.  “facts” are not learned; instead, how to use visual information, how to operate this optical instrument, and what exists in unseen worlds, are learned;

4.  microscopy is very conducive to classroom discussions and Q&A, and is suitable both for individual efforts and group work;

5.  optics of microscopes can be extended to also involve binoculars and telescopes;

6.  students will learn both about optics and microscopes and about the different specimens being examined and discussed; and,

7.  microscopy is fun!  Dr.M. and some other scientists even consider microscopes to really be toys, as well as research tools!

One example of a primary school science class using light microscopy. 

This laboratory class uses magnifying glasses (see: “Part 2” ) and dissecting light microscopes to examine a paper towel, a sheet of notebook paper, a bird feather, and skin on the human arm.  It is preceded by a full introductory class that defines and explains lenses, magnification, resolution, and the basic design of the dissecting light microscope.  Students each will study one specimen at a time; between specimens, their teacher engages them with questions and discussion.

In this primary school science class, the students should learn:

1.  the practical aspects of what was presented in the preceding introductory class;

2.  differences in magnification and resolution for the naked eye, a magnifying glass, and a dissecting light microscope;

3.  that not everything which exists can be seen by our own eyes;

4.   that papers are made of small fibers compressed together to varying degrees;

5.  that flight feathers of birds are complex structures made of regularly spaced fibers attached to a stiff  backbone strut; and,

6.  that several sizes of hairs are present on normal human skin.

Duration for this lab session can be from 1-3 hours.  If needed (e.g., because class time is limited to 45-60 minutes in length), the session described can be enlarged to become 2-3 consecutive sub-sessions;  in that case, the specimens can be divided amongst the different periods.  Note that everything listed above is done without imaging; if imaging is available, it certainly should be used and additional time will be needed.  Ideally, this class can be followed later by another class working with compound light microscopes.

One example of a set of secondary school science classes involving microscopy. 

For secondary schools, science classes using microscopy can be more detailed, and will include: (1) more emphasis upon  the specific specimens being examined, (2) making actual calibrated measurements with a light microscope, and, (3) discussions and Q&A at a more advanced level.  Electron microscopy also should be included (see next section).

This example uses a set of 3 consecutive sessions.  The first class will instruct about the general design of a compound light microscope.  A second class either will use compound light microscopes, or will watch projected images of one being used by their teacher, with 4 specimens: (1) a piece of a paper towel, (2) a piece of notebook paper, (3) a stained blood smear, and (3) a drop of pond water containing some protozoa.  If available, imaging is performed and copies are distributed for each student’s notebook.  The third class will be a Q&A session covering measurements of length; this features how images are calibrated for making size measurements, and an introduction to the standardized science scales for length.  The first and third sessions will last for one hour each; the second class might require 2 or more hours.

In this secondary school science class, the students should learn:

1.  the concepts for magnification, resolution, and practical usage with magnifying glasses, dissecting light microscopes, and compound light microscopes;

2.  what can be visualized in a paper towel and a piece of notebook paper with a  magnifying glass, dissecting light microscope, and compound light microscope;

3.  what differences can be visualized in a stained smear of blood cells with the naked human eye, a dissecting light microscope, and a compound light microscope;

4.  what are the standard scales for linear size;

5.  how are accurate length measurements of small sizes made with microscopy; and,

6.  how small are red blood cells?

Treatment of electron microscopy for science classes in secondary schools. 

Only very few secondary schools have an electron microscope in-house.  This important aspect of microscopy thus must be taught by showing images and videos, both of which are readily available on the internet (see “Part 3” ).  At the very least, secondary school students should learn (1) the basic design of the transmission and scanning electron microscopes, and (2) their operational capabilities; this instruction can be given in one hour.  In addition, a second hour-long class will present discussion of the most fundamental differences between light microscopes and electron microscopes:

1.   electrons are charged, but photons are uncharged (i.e., they are neutral); thus, electron microscopes use electromagnetic lenses, while light microscopes use glass lenses;

2.  electron microscopes have better resolution and give higher useful magnifications than do light microscopes;

3.  electron microscopes can visualize individual atoms, unlike light microscopes;

4.  light microscopes can image living cells, unlike electron microscopes;

5.  light microscopes easily can produce no radiation damage, unlike electron microscopes;

6.  light microscopes can examine wet or hydrated specimens much more easily than can electron microscopes; and,

7.  electron microscopes cost much more to purchase and operate than do light microscopes.

Lets go beyond the usual classroom teaching! 

One very special approach for teaching about electron microscopy in schools is to invite an electron microscopist from a local university or industry to present a gratis illustrated session describing what they do with electron microscopy in their work.  For this teaching activity to succeed in secondary schools, the visitor absolutely must: (1) simplify their presentation from the usual very detailed coverage, (2) not use more than a few specialized terms, and (3) leave a good 15 minutes (out of 50-60 total) for student questions about electron microscopy.  I know that almost all electron microscopists would be pleased to contribute to local science education of schoolchildren (or adults!) in this way; the Microscopy Society of America provides instructions on “Locating a Microscopist-Volunteer” , which offers helpful advice for finding a suitable presenter.

Resources for science teachers about using microscopy in their classes.

There is an amazing amount of help available!  Science teachers need not fear the fact that they have never before operated a microscope, because there are good instructional programs for their learning to do that.  These include workshops on “how to do it” for light microscopes.  Very much guidance, instruction, and practical help is available on the internet, including articles by teachers about their experiences with using microscopy in a school classroom.  For example:

(1)  Commercial manufacturers of light and electron microscopes, digital cameras, and microscopy accessories often offer extensive instructional material on their websites.

(2)  Some light microscopes now are specifically manufactured for use in school classrooms, and cost much less than any used or new research instrument.  Look up “light microscopes for schools” or “teaching light microscopy” in any Web Browser, and you will see prices and descriptions about what is available.  For extensive guidance on the essential tasks of selecting what to buy and finding funds for purchasing, see:  https://www.microscopy.org/education/projectmicro/buying.cfm .

(3)  Some well-designed classes and needed materials for light microscopy are available commercially.  These include complete kits with teaching guides and student manuals, raw specimens and prepared slides, and, all needed small equipment.

(4)  Useful advice from teachers who already are using microscopy in their science classes is presented on quite a few websites (i.e., search for “Microscopy in the classroom” or “Teaching microscopy in schools”).

(5)  “Microscopic Explorations” is a much acclaimed guidebook by GEMS (Great Explorations in Math and Science) that is targeted to Grades 4-8 in primary schools  ( http://lhsgems.org/GEMmicro.html ).

Concluding remarks. 

Both light and electron microscopy are used extensively in industry and in all 3 branches of science.  Microscopes can play a significant role for science education in primary and secondary schools.  Use of microscopy in the classroom is distinctive because it: (1) involves eyes, hands, and the brain; (2) emphasizes learning for doing and understanding, rather than just acquiring another bunch of facts; and, (3) is directly related to learning about other topics in science and non-science.  Teachers of science should seek to become more aware  of what class modules already are available, and of the opportunities that teaching microscopy will provide to elevate the effectiveness of their classes.

Recommended by Dr.M for science teachers: further good internet resources. 

1.  Several very useful instructional materials for using microscopes in the classroom are offered by the Microscopy Society of America (see “Project MICRO” at:  https://www.microscopy.org/education/projectmicro/index.cfm ).  This national science society offers over 300 educational DVDs on all aspects of microscopy; some are good for young students in schools (see: https://www.microscopy.org/education/dvdlibrary.pdf ).   

2.  Hooke College of Applied Sciences and the McCrone Group offer a good description of their programs to instruct science teachers to use light microscopes, so they then can teach this in their classes (see:  “Education – Helping Teachers Use Microscopy to Engage Students in Science” ).

3.  For a fascinating video story about a graduate student (Mark McClendon) giving presentations on scanning electron microscopy to classes of young students, see: “Beyond the Bench: Bringing Electron Microscopy into the Classroom” by Bethany Hubbard (2014).

4.  A good list of microscopy websites is available from the John Innes Centre in the U.K. at:  http://www.jic.ac.uk/microscopy/links.html .  The Microscopedia web site features applications of microscopy to primary school education, and, includes a variety of news and reports from the world of microscopy (see: http://www.microscopedia.com/Resource/Application/22?ccgid=4 ).

 

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MICROSCOPY FOR RESEARCH, EDUCATION, AND FUN! PART 3: ELECTRON MICROSCOPY.

 

Schematic Diagram showing Major Parts in a Transmission Electron Microscope.   (http://dr-monsrs.net)
Schematic Diagram showing the Major Parts in a Transmission Electron Microscope.    (http://dr-monsrs.net) 

Few research instruments are as widely used in science as are microscopes.  I will present a very brief description of microscopy and the many different types of microscopes by this series of articles.  These are not in-depth discussions, but rather are designed to provide an understandable background about microscopy for teachers, technicians, students, parents, and other beginning users.  Since I want to keep everything concise and suitable for non-experts, I will not give the usual optical equations and mathematics, ray path diagrams, or standard instructions about how to use these microscopes!

The fundamental concepts and general terms for using microscopes and understanding microscopy were covered by “Part 1” , and light microscopy was presented by  “Part 2” .  Part 3 now presents electron microscopy; all beginners should first study Part 1

Waves and optics: electrons and photons. 

Electron waves/particles have several differences from light waves and photons: (1) electron waves are much smaller, meaning that resolution in electron microscopes is better than in light microscopes; (2) electrons are negatively charged, while photons are neutral, meaning that electron microscopes must utilize electromagnetic lenses rather than the glass lenses used for light microscopes; (3) electrons can be transmitted through only very thin specimens (e.g., 50-100 nanometers in thickness), meaning that the usual 5-10 micrometer thickness of slices used for light microscopy are not usable for electron microscopy because far too few electrons will be transmitted to reach the detector; and, (4) unlike photons,  electrons interact very strongly with all atoms and molecules, therefore necessitating keeping their pathway inside electron microscopes at a high vacuum level.  Beyond these prominent distinctions, the optics of electrons in electron microscopy have counterparts with the optics of photons in light microscopy; however, a multitude of controls for the vacuum system, high voltage generation, coordinated electronics and monitors, cameras, and associated accessories make electron microscopes much more complex than any light microscope. 

General design of electron microscopes. 

The chief components in electron microscopes are shown in the highly schematic diagram given above under the title.  Many other parts are not depicted (see text for details!).  This diagram can be readily compared to that given for compound light microscopes in the previous article (see: “Part 2”).  Electron microscopes commonly are divided into 2 fundamental types depending upon how the specimen is irradiated by the beam of electrons (i.e., all at once, or point by point).  

Different kinds of electron microscopes: common transmission electron microscopes.  

For these instruments. an entire area of a specimen is irradiated by the electron beam all at once.  Major components are kept in a high vacuum inside the column.  Electrons are generated at high voltage (e.g., 50-1,000kV) from the electron gun (electron source) by emission induced from a hairpin or a pointed filament.  An anode in the gun then draws the stream of electrons down the column into the several condenser lenses; these focus the beam onto the specimen.  After transmission through a very thin specimen, the beam then passes into the objective lens.  This strong lens contains an objective aperture (i.e., a sheet or disk of metal with a precise very small hole centered on the optical axis); this intercepts those transmitted electrons which have been strongly scattered by atoms in the specimen and prevents them from reaching the plane of detection, thereby   creating image contrast.  A series of several other electromagnetic lenses follows and acts to  increase the magnification of the transmitted image; magnifications can range from 100X up to 1,000,000X.  The transmitted electrons finally are received by an electron detector in a photographic or digital camera which records the image (i.e., an electron micrograph).  In addition to images, electron diffraction patterns from crystalline specimens also can be recorded.  Special attachments to transmission electron microscopes extend the capabilities of these instruments for diverse samples (e.g., frozen-hydrated specimens with cryomicroscopy, special specimen chambers for chemical reactions with in-situ microscopy and analysis, etc.).   

Different kinds of electron microscopes: scanning electron microscopes. 

These electron microscopes are functionally analogous to dissecting light microscopes, in that the natural or sliced surface of specimens is imaged.  The beam of electrons is focused to a fine point by condenser lenses, and then is directed onto a specimen with a raster pattern, similarly to the way a television image is formed.  Unlike transmission electron microscopes, minute parts of the specimen area to be examined are irradiated consecutively rather than all at once.  Scanned imaging uses different electron detectors to capture one of several available signals (e.g., secondary electrons emitted by the specimen surface in response to being hit by the incoming primary electrons, backscattered electrons reflected from the specimen surface, etc.); these electron signals are received by a detector located above the specimen (i.e., the electrons forming an image are not transmitted through the specimen).  Magnifications generally range from 10X to 30,000X. 

Contrast in scanned images is mainly due to differences in topography and atomic composition of the specimen.  These mechanisms produce different numbers of detected electrons, thus providing image contrast.  Images from secondary electrons in scanning electron microscopes often have a 3-dimensional character due to shadowing by neighboring parts of the specimen.  Image resolution levels usually are influenced by the characteristics of each specimen.  Scanning electron microscopes mostly are used to image much finer details in surface structures than are given by a dissecting light microscope; however, resolution is poorer than that produced by transmission electron microscopes. 

Different kinds of electron microscopes: scanning-transmission electron microscopes.

 A third version of electron microscopes also exists, and is a hybrid of the two described above.  Scanning-transmission electron microscopes irradiate the sample in a sequential raster pattern like scanning electron microscopes, but still form images from those electrons that are transmitted through the specimen (i.e., the electron detector is on the far side of the specimen, unlike the case for scanning electron microscopes).  This optical arrangement can achieve atomic resolution and is utilized particularly for compositional mapping and for very high resolution imaging.   

A number of specialized and experimental electron microscopes also are available for research usage, but will not be covered in this introductory presentation.  

Specimen preparation for electron microscopy. 

For study by transmission electron microscopy, good  preparation of samples is vital in order to achieve high quality, reproducible, and artifact-free results.  Samples most frequently are mounted onto a very thin film of carbon or plastic; this support film is held upon a metallic grid (i.e., similar to a window screen, but much thinner and smaller).  Rocks and minerals, tissues, organs, and industrial products all must be prepared by slicing, thinning, or polishing into a thin enough state to permit the electron beam to penetrate through the specimen.  In biology, specimens are chemically (i.e., buffered cross-linkers) or physically (i.e., very rapid freezing) fixed, then are dehydrated and embedded, and finally are sliced into ultrathin sections using an ultramicrotome (i.e., a special finely controlled cutting machine); these slices commonly are stained by heavy metal solutions in order to increase the image contrast.  Electron microscope immunocytochemistry with specific antibodies is used to locate various protein components in ultrathin sections.  Rapid freezing is used to prepare macromolecules and cells for electron cryomicroscopy; the frozen-hydrated unstained specimens are kept at liquid nitrogen or liquid helium temperature inside the electron microscope, thereby maintaining their native structure. 

For scanning electron microscopy, non-conductive specimens must be treated by coating them with a conductor so they become conductive.  Sample preparation aims to produce specimens that are (1) dry (i.e., simply putting a moist specimen into the high vacuum of an electron microscope will cause its collapse and other structural changes), (2) conductive (i.e., non-conducting samples give bad images due to their becoming charged under the beam), (3) producing a high level of signal (i.e., coating with a thin layer of metal produces increased numbers of secondary electrons, thus giving a brighter image), (4) compatible with higher resolution imaging, and, (5) free from artifacts.   

What are electron microscopes actually used for? 

The several different kinds of electron microscopes are used very extensively for imaging, diffraction, and analysis in all 3 branches of science, and also in industry.  For research, they are utilized to examine normal, abnormal, and experimental structure, along with the amount and distribution of compositional elements.  Other major uses include atomic level imaging, spectroscopy, and experimental electron optics.  For crystallography in bioscience and materials science, electron diffraction patterns are essential for structural characterization; electron crystallography is an important special branch of applied electron optics.  Enormous efforts have been devoted to producing better specimen preparation, since that has such a clear importance for determining exactly what can be imaged, detected, and meaningfully studied.

Correlative microscopy uses electron microscopes to obtain higher resolution details for specimens that first were imaged at moderate resolution and magnifications (e.g., by light microscopy).   Their enormous range of magnifications can permit correlative microscopy to be conducted by a single transmission or scanning-transmission instrument.   As one real example, defects and inclusions in semiconductor devices are first characterized by scanning electron microscopy and then analysis of their elemental distribution is mapped with a scanning-transmission electron microscope.  

For those of us using electron microscopes in our daily work, they also provide quite a lot of fun!  Electron microscopists are analogous to airline pilots looking down at a landscape!  

The chief advantages and the chief problems of electron microscopes. 

All electron microscopes stand out for their ability to image structure at higher resolution levels than can be achieved by light microscopy.  Atomic-level structure now can be directly imaged; this capability is usable for many kinds of specimens, and excels for nanomaterials and materials science.  

Electron microscopes are quite costly and purchase often can be justified only when made for a group of multiple users.  Routine and special specimen preparations frequently are expensive, hazardous (due to exposure to toxic chemicals and nanoparticles), and give good results only with much training and experience of the technician or microscopist.  The biggest problems for electron microscopy of biosamples, polymers, and wet materials are that: (1) they must be either frozen or dried, both of which easily can cause undesired changes in their native structure, and, (2) the same illuminating electrons that enable imaging also cause radiation damage to the specimen, thereby changing their native structure.  Good images of artifacts are commonplace. 

Recent developments in electron microscope instrumentation. 

Modern electron microscopes have become increasingly sophisticated and specialized in their capabilities.  The recent commercial production of correctors for electron optical lens aberrations now permits the measured level of resolution to be equal to the calculated theoretical resolution limit; this permits better atomic imaging and better compositional analysis to be achieved.  New experimental approaches for the electron source, camera, and optical design are progressing nicely; new instrumentation accessories and new software are being developed every year. 

Electron microscopy in science education. 

Electron microscopy is very widely used in science education at secondary schools and colleges, but all that is almost completely hidden from students by their teachers!  The source and nature of the many images from electron microscopy shown in classrooms are only rarely indicated!  Examples of this silent treatment include cells and tissues, organelles and macromolecules, bacteria and viruses, solid state devices, polymers, fibers, minerals, metals and alloys, nanomaterials, etc. 

Courses on electron microscopy mostly are found only in larger universities and specialized educational institutions.  Recently, some manufacturers and certain institutions are offering opportunities for students and classes to use scanning or transmission electron microscopes having computerized control systems, either via the internet or by visiting a working facility.

Concluding remarks. 

The different kinds of electron microscopes have a high practical importance for enabling diagnosis of kidney diseases by examination of renal biopsies, reliable detection of causes for manufacturing defects and malfunctions in semi-conductors, advancement of understanding of normal and pathological cell substructure, detection and identification of disease microbes, development of nanomaterials and nanomachines, etc., etc.  Technology developments for electron microscopes and for advanced specimen preparation are progressing vigorously in the modern world.   

Let us now take a look at some images from electron microscopes!

Examples of images produced from all 3 kinds of electron microscopes are easily available on the internet.  The following are recommended to you by Dr.M.  

(1)  A GOOD PLACE TO START:  The semi-popular monthly journal, Microscopy Today, will give a good taste about what is going on currently (see: http://microscopy-today.com/jsp/common/home.jsf ).  Most manufacturers of electron microscopes and related accessories have full-page advertisements in each issue.  Articles about microscopy in education are a regular feature of this publication.

(2)  A GALAXY OF IMAGES:  For galleries with a multitude of images and diagrams, look up each of the 3 kinds of instruments (“transmission electron microscope”, “scanning electron microscope”, and “scanning-transmission electron microscope”) in the image section of your favorite internet browser.  When you find something of personal interest among the many hundreds of panels shown, click on its thumbnail and you will be taken to the explanatory details directly provided by its source.

(3)  ELECTRON MICROSCOPY OF NANOPARTICLES:  Electron microscopy excels with specimens from nanoscience!  Go to the website of the Nanoparticle Information Library at http://www.nanoparticlelibrary.net/results.asp and enter a search for “electron microscopy”; you will receive electron micrographs for 24 quite different nanoparticles, along with a brief report for each.

 

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