bluuebunny/crossref_metadata_2025_split huggingface dataset:
The nucleation of recrystallization at second phase particles in 7000 series deformed aluminum alloy
Authors: Hidalgo-Prada B. , Guilarte J.J. , Paredes S.Y. 
Published: June 2020

An investigation was carried out to determine the effect of a thermomechanical process (TMP) in the precipitation of dispersed second phase particles, and to assess the recrystallization behavior of a deformed ALCANVEN-7475 commercial aluminum alloy. The TMP included solution anneal treatment at Ts = 482°C for 3 hours, overaging at temperatures (To) in the range from 160 - 400°c for 1 to 30 hours, cold and warm deformation up to 90% reduction of thickness (RA) and recrystallization at Tr = 482 °C for 15 to 60 minutes.A Hitachi H-600 TEM operated at 100 KV was utilized to examine the microstructural evolution of the alloy leading to the nucleation of recrystallization as a consecuence of the previously described four steps TMP.It was determined that the nucleation of recrystallized grains is promoted by the presence of second phase particles with critical sizes between 0.5 and 1.0 μm.
Differential phase contrast in TEM for magnetic micro structure observation
Authors: Kruit P. , Buist A.H. , McCartney M.R. , Scheinfein M.R. 
Published: June 2020

Phase contrast in TEM can only give information in a limited band of spatial frequencies. The differential phase contrast mode in STEM does not have this limitation, since one simply measures the angle over which the electron beam is deflected by the specimen. This is useful, for example, for determining the magnetic field distribution in magnetic thin films. Recently, a form of electron holography was developed, also in STEM, to obtain differential phase contrast images. In this method, the illuminating beam is split by a biprism in such a way that there are two mutually coherent electron source images close to the specimen. On a far away CCD detector, two shadow images are formed which interfere to give a fringe pattern. It is this fringe pattern that contains the differential phase information. Here, we show that differential phase contrast can also be obtained in a TEM.In the TEM, two coherent illuminating beams are created by a beam splitter in the condenser system. These beams can be treated as two plane waves, creating a fringe pattern in the plane of observation,as shown in figure 1.
The NCEM public domain software library of extensions to digital micrograph
Authors: Kilaas Roar , Paciornik Sidnei 
Published: June 2020

The National Center for Electron Microscopy (NCEM) develops software for use in image processing and image interpretation as they are needed in ongoing research at the center. Some routines are esoteric and of little use to others, while some are more general and could be considered to be of interest to a large number of scientists. This represents the first announcement of the NCEM's dedication to making software developed at the center available to the general microscopy community.An unfortunate by-product of software development is the often necessary connection of the software to a hardware platform and/or another software platform. Most of the image processing carried out at the NCEM is done under Digital Micrograph running on the Macintosh, either through the built in functionality of the program or through extensions that are written at the center. Some of the functionality that we added were routines that were available under the SEMPER image processing software which was retired not because of limitations of the program, but because of the death of the hardware on which it was running.
Using correlative microscopy (LM, EM, and SFM) in biological problem solving
Authors: Albrecht R.M. , Wetzel B. 
Published: June 2020

Conventional morphologic approaches generally place a heavy reliance on standardized preparative methodology and often are narrowly designed to provide supporting documentation for preexisting lines of evidence or for a particular interpretation thereof. Visual images constitute a particularly convincing form of data and several well chosen micrographs can be the difference between studies which are deemed publishable and those that are not.The potential, however, for imaging methodology to go beyond a “supporting” role and allow investigators to ask and answer questions not approachable by other methodologies is considerable. This has always been the case but relatively recent developments have strongly reinforced this potential. The application of several imaging based technologies to parallel specimens or, preferably, to the exact same specimen in series is the basis for correlative microscopy. Appropriate tracking and imaging of living cells and the subsequent correlative observation of the same cells following immobilization by various physical or chemical based preparative procedures can provide a wealth of information, which bears not only on the biological question at hand but on the likelihood and/or extent of preparative “artifact” as well.
The multianalytic approach; or yes, you can get there from here! Problem solving in semiconductor manufacturing
Authors: Ecker M. M. 
Published: June 2020

Manufacturing, development and failure mode analysis problems, in the semiconductor industry, present unique challenges and opportunities, not only to utilize several analytical techniques, but to process and deprocess samples into an appropriate format for analysis. In today' s' cleanrooms a great deal of development is integrated into the manufacturing line. This, combined with the ever decreasing size and increasing density of components on a single integrated circuit, creates the need for accurate as well as precise measurements. The method of measure must be appropriate to the task, compatible with the manufacturing environment, and useful in a process control system.Current complimentary bipolar technologies, utilizing shallow junction implants, require additional as well as less robust processing in order to maintain the depth and latitude of the junction. Additional processing includes the formation of a contact window spacer. The spacer is formed, following implant and thermal anneal, by growing and subsequently removing a thermal oxide layer. In the manufacturing process, oxide removal is verified by optical measure using visible light.
Microscopic detection of Giardia trophozoites in archival pathology specimens of human small intestine: light microscopy, low voltge SEM, and confocal scanning laser microscopy using fluorescent in situ hybridization
Authors: Macechko P.T. , Mulgrew T. , van Keulen H. , Jarroll E.L. , Snover D.C. , Erlandsen S.L. 
Published: June 2020

In situ hybridization methods have been widely used for the analysis of chromosomal markers, and for the detection and identification of various species of bacteria in environmental samples. In situ hybridization probes to ribosomal RNA have been used as a diagnostic tool for the study of various parasitic protozoa, and fluorescent in situ hybridization (FISH) probes have been used to study the intracellular distribution of mRNA.The intestinal protozoan, Giardia, colonizes the small intestine of a variety of different animals, including humans, and forms an infective cyst stage which is responsible for host-to-host transmission. Light microscopic detection in environmental or fecal samples has relied on the detection of cysts whose presence may be infrequent. In human giardiasis, confirmation of diagnosis has often required microscopic analysis of intestinal biopsies for detection of trophozoites. Analysis of the molecular sequence of 16s rDNA (small subunit) in Giardia isolates has permitted the development of species specific probes for Giardia.
Structural analysis of endothelial cell mediated prolongation of t-PA driven lysis of an “aged clot”
Authors: Jerome W.G. , Handt S. , Hantgan R.R. 
Published: June 2020

In an effort to reestablish blood flow in blocked coronary arteries, heart attack victims are now routinely treated with thrombolytic (clot busting) drugs. However, thrombolytic therapy fails to restore sufficient flow in approximately 20% of cases. The reasons for these failures are undoubtedly multifactorial and difficult to study in vivo. We have developed an “in vitro” model blood vessel which allows controlled study of factors influencing thrombolysis. In the studies reported here, we investigated the 3-D distribution of HUVEC secreted PAI-1 within the clot using immuno-gold cytochemistry and intermediate voltage electron microscopy (IVEM).Human umbilical vein endothelial cells (HUVEC) were grown on the inside surface of fibronectin-coated glass tubes. The cells are stimulated for 4 hours with 1000 U/ml of TNF-α. Clot formation was initiated by addition of 2.3 μM fibrinogen, 100 nM plasminogen, and then 2 nM thrombin in HEPES buffered Gey's salts + 0.5% human serum albumin. After aging the clot for up to 4 hours (to mimic the time delay between heart attack and treatment), 0.5 nM rt-PA (thrombolytic agent) was perfused through the clot for 10 min. at 5 ml/hr. Formation and dissolution of the clot were monitored by laser light scattering.
Exhaustive photon reassignment™: a method for performing high-resolution, quantitative 3-D fluorescence microscopy
Authors: Moorthy Ramkumar K. , Hitrys David C. 
Published: June 2020

Fluorescence microscopy is an increasingly popular technique in the field of light microscopy. However, when one uses an objective lens of high magnification and numerical aperture, only a very shallow plane within the specimen is in optimal focus. Out-of-focus fluorescent objects in planes above and below this plane of focus contribute light haze to this plane, compromising the visual quality of the specimen image. This haze also renders it impossible to accurately quantify light intensities of fluorescent objects present in this plane.Confocal microscopy is one technique that allows researchers to obtain a highly resolved, high-contrast image of a specimen plane by excluding or rejecting light emanating from out-of-focus planes. Most biologists, however, can illafford to discard valuable fluorescence energy, because its efficient use would allow for optimal imaging conditions, and because it does contain useful information even if emanating from out-of-focus structures. There are also other drawbacks associated with confocal technology. The laser used as the excitation source in a confocal microscope is not really suitable for live cell studies, and also limits the range of fluorochrome labels that may be used.
3-D structure of single macromolecules at 15Å resolution by cryo-microscopy and angular reconstitution
Authors: Dube Prakash , Stark Holger , Orlova Elena V. , Schatz Michael , Beckmann Erich , Zemlin Friedrich , van Heel Marin 
Published: June 2020

Electron cryo-microscopy of individual non-crystallized macromolecules (“single particles”) is a very rapid technique for probing the three-dimensional (“3D”) structure of biological macromolecules. By exploiting the different orientations of the macromolecules in the embedding medium, one may extract 3D information from the data without ever collecting tilt series in the microscope. The angular reconstitution approach, designed for this purpose, was recently extended with a number of refinements which allow its use as a routine technique for finding 3D structures of macromolecules with arbitrary pointgroup symmetry, from entirely asymmetric ribosomes to viruses with icosahedral symmetry.The specimen preparation technique associated with the angular reconstitution approach is simple and fast since crystallization experiments are avoided altogether. The vitreous-ice embedding specimen preparation technique remains one of our favorite specimen preparation techniques. We are, however, currently experimenting with specimens embedded in glucose and ammonium molybdate or other heavy-metal salts. Collecting good micrographs can also be quite straightforward since the images are taken from untilted specimens, while exposing each image area only once.
En face dual fluorescence staining of fatty streaks allows observation of initiation and progression of atherosclerotic lesions
Authors: Klinkner Anne M. , Waites Crystal R. , Bugelski Peter J. , Kerns William D. 
Published: June 2020

A primary effort in the understanding of the progression of atherosclerotic disease has been methods development for visualization of the atherosclerotic plaque. We introduce a new method for the qualitative analysis of lipids in atherosclerotic fatty streaks which also retains those lipids for biochemical evaluation. An original aspect of the process is the ability to view an entire fatty streak en face, selectively stained for specific lipid classes within the lesion.New Zealand white rabbits were fed a high cholesterol diet(0.15%-0.3% for 14 wks). The aorta was removed and fixed in Carson's phosphate buffered formaldehyde followed by dual staining in the fluorescent dyes Nile red and filipin. Stock solutions of nile red(0.5mg/ml acetone) and filipin(2.5mg/ml dimethyl formamide) were prepared and kept at -20°C; all subsequent steps were at RT. 0.5cm × 1.0cm pieces of aorta were trimmed and adventitia removed. The pieces were then washed 3×15 min in PBS w/o CaMg, soaked in Nile red(NR)/filipin(Fl) stain(100(il NR stock + 200μl Fl stock in 10 ml PBS for 30 min, washed in PBS 3×30 min, rinsed with distilled water, mounted(Crystal Mount, Biomedia) and coverslipped and viewed by fluorescence microscopy.
Accumulation of smooth tubular membrane aggregates in the vitellogenic oocytes of an insect, Dysdercus cingulatus
Authors: Kömüvest László G. , Sasst Miklós 
Published: June 2020

The accumulation of vitellogenins in the oocytes of insects is a receptor-mediated endocytic process, which leads to the formation of yolk granules. We have been studying the hormonal regulation of vitellogenin accumulation and yolk granule formation in the red cotton stainer, Dysdercus cingulatus (Insecta, Hemiptera). During our investigation we observed the appearance of extensive aggregates of smooth tubular membranes in the vitellogenic oocytes. In this report we describe the ultrastructural features of these new cellular organelles.In D. cingulatus (as in other insects) the onset of vitellogenesis (i.e. yolk accumulation) is marked by the appearance of coated pits between the microvilli (Fig. 1). The coated pits transform into electron dense coated vesicles upon invagination into the cortical ooplasm and their subsequent fusion leads to the formation of yolk granules. At a later stage the fusion and continuous growth of yolk granules gives rise to large yolk platelets. During the early phase of yolk accumulation the cortical ooplasm also contains non-coated vesicles of different size in a large number (Fig. 1).
Insulin-like growth factor i and demyelination: cytochemical evidence for free radical derived oxidant mediation
Authors: Ann Ellis E. , Grant Maria B. , Mames Robert N. 
Published: June 2020

The peptide hormone, insulin-like growth factor I (IGF-I) is a growth factor which has been shown in elevated concentrations in the serum and vitreous of diabetic patients with proliferative diabetic retinopathy. Studies with an animal model of IGF-I induced proliferative retinopathy2 showed demyelination in the optic nerves and along the medullary rays of rabbit eyes which received intravitreal injections of IGF-I, basic fibroblast growth factor (bFGF), or a combination of the two growth factors. Biochemical studies have demonstrated a role for oxidative injury in complications of diabetes including lipid peroxidation and demyelination in peripheral neuropathy. The cerium NADH-oxidase technique has been used to demonstrate free radical derived oxidant production in several pathological conditions including demyelination in experimental allergic encephalomyelitis (EAE). We investigated the role of free radical derived oxidants in growth factor-induced demyelination.Pigmented rabbits were injected intravitreally with 500μg of IGF-I or bFGF and sacrificed at 4, 8,12 and 18 days.
Endophytic relationship between an entomopathogenic fungus Beauveria bassiana and corn (zea mays)
Authors: Wagner Bruce L. , Lewis Leslie C. 
Published: June 2020

Fungi are known to colonize plants, usually as phytopathogens or symbionts. This is the first report of the entomopathogenic fungus, Beauveria bassiana (Balsamo) Vuillemin (Deuteromycotina: Hyphomycetes) penetrating and colonizing a plant in a manner similar to when it invades a typical insect host Ostrinia nubilalis Hübner (Lepidoptera: Pyralidae). Electron microscopy was used to document this fungus penetrating the leaves of corn (Zea mays) and establishing an endophytic relationship within the plant.Several studies have shown B. bassiana to adhere to insect cuticle and penetrate with or without forming appressorial penetration structures. Investigations have concluded that the young, germinating hyphae may produce sequentially a proteinase followed by chitinase to dissolve the cuticular envelope of target insects. Within three days after inoculation, viable B. bassiana conidia germinated and formed vegetative mycelia which grew randomly over the corn leaf surface (Fig. 1). Often a germ tube is formed from a conidium and elongates only a short distance before terminating its growth and penetrating the leaf surface (Figs. 2 and 3).
Structural studies of Na,K-ATpase
Authors: Mohraz M. , Yee M. , Smith P.R. 
Published: June 2020

Na,K-ATPase, an integral protein of the plasma membrane of eukaryotic cells, derives energy from ATP hydrolysis for the active, coupled transport of Na+ out of the cell and K+ into the cell. The enzyme can be purified in membrane-associated form (1). It consists of two polypeptide chains: α(Mr=100,000) and β(Mr=50-60,000).Two dimensional arrays of the enzyme were induced by partial removal of its phospholipids by phospholipase A2, and in the presence of variousions. The arrays were exclusively dimeric with an (αβ)2 structure in the unit cell (Fig. 1). SDS polyacrylamide gel of the crystalline sheets is presented in Fig. 2. It shows an identical pattern with the same relative ratio of α:β subunits, to that of the pure enzyme.
Lattice imaging of precipitates in Al-Zn-Mg alloy
Authors: Wu C. K. 
Published: June 2020

The precipitation phenomenon in Al-Zn-Mg alloy is quite interesting and complicated and can be described in the following categories:(i) heterogeneous nucleation at grain boundaries;(ii) precipitate-free-zones (PFZ) adjacent to the grain boundaries;(iii) homogeneous nucleation of snherical G.P. zones, n' and n phases inside the grains. The spherical G.P. zones are coherent with the matrix, whereas the n' and n phases are incoherent. It is noticed that n' and n phases exhibit plate-like morpholoay with several orientation relationship with the matrix. The high resolution lattice imaging techninue of TEM is then applied to study precipitates in this alloy system. It reveals the characteristics of lattice structures of each phase and the orientation relationships with the matrix.
Element analysis with the imaging electron energy loss spectrometer of the zeiss EM 902
Authors: Bihr J. , Rilk A. , Miller W.I. 
Published: June 2020

An imaging electron energy loss spectrometer can be used to produce elemental maps with highest spatial resolution by Electron Spectroscopic Imaging (ESI). Simultaneously, electron energy loss spectra (EELS) can also be recorded. It is therefore simple to combine morphological examinations with the analytical method of electron energy loss spetroscopy (Figs. 2, 3)The electron energy loss spectrometer of the EM 902, used in combination with a suitable electron detector (Fig. 1), provides the possibility of recording electron energy loss spectra over an energy loss range from 0 to 2000 eV. In this way, all elements of the periodic system can be detected via their K, L, M, N or O absorption edges (Fig. 5). Unlike X-ray microanalysis, this technique is especially suitable for detecting light and medium-heavy elements which are of special significance in biological and medical research.
Mark II Test Vehicle Holder for in Situ Viewing of Integrated Circuit Electr0Migrati0N
Authors: Maskowitz J. V. , Rhoden W. E. , Kitchen D. R. , Omlor R. E. , Lloyd P. F. 
Published: June 2020

A patent pending test holder was designed to support research in electromigration using a JEOL 100 CX STEM. The holder provides electrical connections for an aluminum stripe test vehicle which allows the electromigration process to be conducted within the microscope.The holder is specifically designed for use in conjunction with a JEOL-type electron microscope side entry goniometer. Four leads provide the ability to power three different test stripes on one test vehicle. This allows three separate electromigration runs/observations in-situ without removing the test vehicle from the STEM, thus minimizing test vehicle time outside the vacuum environment.
Fixation artifacts in percutaneous needle biopsies of liver
Authors: Januszewski T.C. , Harb J.M. , Komorowski R.A. 
Published: June 2020

Percutaneous needle biopsy is a standard procedure for obtaining liver tissues for pathologic studies by light and electron microscopy. Tissues obtained by this procedure usually measure 1mm to 1.5 mm in diameter, and can be placed immediately at the bedside into a standard glutaraldehyde fixative for processing by the electron microscopy laboratory. Although the biopsy thickness is within the penetration range of glutaraldehyde, we have noted a significant loss of preservation in the center of most liver biopsies. The loss is apparent at light and electron microscopic levels. The purpose of this paper is to illustrate the artifact and to discuss the importance of avoiding the artifact when selecting areas of the specimen for electron microscopic studies.Secimens studied were routine liver biopsies submitted to the electron microscopy laboratory after an initial fixation of one hour in 2.5% glutaraldehyde in 0.1M cacodylate buffer. To illustrate the artifact, one-micron thick sections of the entire block face were stained with toluidine blue for light microscopic study (Figure 1).
A newly developed cryofixation appartus for physiological experiments and its application to squid photoreceptor cells
Authors: Ichikawa Michinori , Hanyu Yoshiro , Matsumoto Gen 
Published: June 2020

By cryofixation method for electron microscopy, structural change in squid photoreceptor microvilli accompanied by long period of light illumination has been studied by Tsukita et al., resulting that there are two states of the microvillar cytoskeletal structure under dark- and light-adapted conditions. In this paper we report the structural changes as a function of time after the light pulse application and their physiological significance.For this experiment, we have developed a new cryofixation device which can combine rapid freezing with physiological experiment2 (Fig. 1). The device cryofixes biological specimen at precisely specified time after the light illumination by driving a small silver block cooled down to 10°K with a computer-controlled actuator; that is, for cryofixation, the cooled silver block is pushed onto the specimen put on an experimental bench. Structural change in the microvilli is observed to take place for the specimens cryofixed at the time period over 50 msec after the light pulse is irradiated, but is not observed for the 20-30 msec light-illuminated photoreceptors (Fig. 2).