bluuebunny/crossref_metadata_2025_split huggingface dataset:
Novel Preparation of Precision Planar TEM Specimens for Integrated Circuits Using Dual-Beam Focused Ion Beam
Authors: Ma Zhiyong , Davies Brian , Brandt Jeremy , Baker Brian , Headley Karen , Miner Barbara 
Published: July 2020

Abstract
Preparation of precision planar TEM specimen for failure analysis in microelectronics industry has become increasingly difficult as the critical dimensions of integrated circuits (ICs) continue to shrink down to deep sub-micron regime. Accurate defect localization and endpoint control of specimen final thinning are critical steps leading to successful specimens and defect characterization. Conventional dimple and ion-mill method becomes inadequate for this class of specimen preparation due to poor optical imaging resolution, non-planar polishing, lack of flexible ion beam control and in situ process monitoring for endpoint control. These problems are exacerbated by the high density and a wide range of materials found in IC device structures. In this paper we present a novel method employing dual-beam focused ion beam (FIB) which significantly improves upon these difficulties.
A New Specimen Preparation Technique for Metallographic Evaluation of Lead and Lead Alloys
Authors: Vahaaho JM , Zieliński PA 
Published: July 2020

Abstract
Preparation of lead and lead alloy specimens for metallographic examination is more difficult than preparation of the majority of other metals and their alloys. The troublesome difference is that lead and lead alloys are soft (lead has a Vickers hardness of 4-5 [1,2]), and therefore readily develop a cold-worked surface layer and disturbances in the subsurface layers during mechanical polishing. The specimen softness also allows embedding of the abrasive particles. If not removed, these mechanically introduced artifacts obscure the true structure of the specimen, and in some cases could develop a pseudostructure, especially if excessive frictional heat is involved [1]. Usually etchpolishing, consisting of cycles of alternately etching, polishing, and microscopic examination, is required to remove the above artifacts. This treatment either might not completely remove these artifacts or it might overetch the sample. In addition, etching could introduce its own artifacts, such as tarnishing, etching pits, or both.
Boron Substrates for Particulate X-Ray Microanalysis
Authors: S.Windsor Eric , E.Newbury Dale , D.Kessler John , H.Chi Peter 
Published: July 2020

Abstract
Sample substrates for x-ray microanalysis of particles should be chemically simple and composed of low atomic number elements. Substrates meeting these requirements will generate a minimum number of low energy x-ray peaks that should not interfere with spectra generated by the particles of interest. Elemental carbon fulfills these requirements and carbon planchets are used for the majority of work involving x-ray microanalysis of particles. When particles of interest are carbonaceous, alternate substrates must be sought. Beryllium planchets have traditionally been used for the analysis of carboncontaining particles. However, concerns about beryllium toxicity along with regulations from the Occupational Safety and Health Administration (OSHA) have resulted in diminished use of beryllium as a substrate material. These toxicity issues prompted us to explore the possibility of using elemental boron as a substrate for microanalysis of carbon-containing particles.
Elemental boron is available from chemical supply houses and the material we purchased was in the form of irregularly shaped pieces, approximately 3 cm in the longest dimension.
A Reactor for “Ex-Situ” TEM Catalyst Characterization
Authors: Kliewer CE , Disko MM , Soled SL , DeMartin GJ 
Published: July 2020

Abstract
The microstructural and chemical characterization of catalysts is not only integral to their initial development but also to understanding and controlling their behavior over time. To better elucidate the morphology of these materials and relate physical properties to catalytic properties (e.g., activity, selectivity, etc.), “ex-situ” methods for studying catalysts under reactive conditions have been developed.
Because conventional transmission electron microscopy (CTEM) is conducted under high vacuum conditions, it is difficult to replicate the exact chemical environment of a catalyst (e.g., high pressure, variable gas mixtures, etc) within the TEM. Consequently, most analyses focus on comparing “fresh” and “spent” materials. In general, this methodology provides useful structural information albeit with limitations associated with the comparison of dissimilar regions and the effects of sampling inhomogenieties.
Recent Developments in Mechanical Specimen Preparation for Tem and Sem Applications
Authors: Li W , Q. Wang S , Trussell R , Xu M , Venables RD , Venables D , Maher D , Hirsh EA 
Published: July 2020

Abstract
The continued reduction in the size of critical features in integrated circuits has resulted in the need to develop rapid, site-specific, sectioning techniques to enable efficient physical characterization of the structures of interest. We have implemented a mechanical polishing approach to achieve this objective with the additional goals of maximizing the number of targeted sites in a sample that can be analyzed, and minimizing physically destructive procedures, such as ion beam exposure. Precision sample preparation approaches have been under investigation for both transmission electron microscopy and scanning electron microscopy.
The mechanical specimen preparation approach used in this work is a variant of the well-known wedge polishing technique. Here we use a polishing tool that does not contact the grinding surface, thus allowing precise control of the wedge angle. Prior to sample preparation, the polishing tool head was precision aligned parallel to the platen.
Development And Applications Of Highly Precise Phase Measurement Technique Using Phase-Shifting Electron Holography
Authors: Yamamoto K , Kawajiri I , Tanji T , Hibino M , Hirayama T 
Published: July 2020

Abstract
Today's information-oriented society requires high-density, high-quality magnetic recording media. For the development of such new recording materials, the quantitative observation of magnetic fine structures by electron holography is eagerly awaited. However, the magnetic fields around particles smaller than 50 nm have not been observed because they are too weak to be observed in the usual way. Here, we report a highly precise phase measurement technique, improved phase-shifting electron holography. Using this method, we observed weak electric and magnetic fields precisely. The precision of the reconstructed phase image was as good as 2π/300 rad.
In phase-shifting electron holography, the phase images are reconstructed from a series of electron holograms whose interference fringes are shifted relative to one after another. The shifting of interference fringes is achieved by tilting the incident electron beam, which corresponds to shifting the initial phase of the incident electron waves in a specimen plane.
Live Electron Holography: A Window to the Phase World
Authors: Voelkl E 
Published: July 2020

Abstract
While electron holography has been around for many years (1948, see [1]), the process of obtaining a view into the phase world stayed a tedious one for a long time. When CCD cameras became available and started to replace film, many attempts were made to obtain a “live” view into the phase world. By far the most successful setup for a live phase display is described in [2]. There, Chen et al. use a mixture of digital and analog techniques to obtain phase images at TV-rate. This setup allows to move the sample and/or watch time dependent specimen changes in a unique way, i.e., live in the phase world. The reason why Chen uses a mixture between analog and digital methods is the capability of an optical lens system for fast Fourier processing.
Computers have become significantly faster since Chen's introduction of the mixed setup in 1992 and allow to process holograms rapidly and obtain about one phase image per second on present standard computer systems and acquisition cameras.
Scanning Force Microscopy and Nanomangulation: Studies of Dna and Proteins Involved in Dna Repair
Authors: Erie Dorothy , Ratcliff Glenn , Guthold Martin , Bullock Valerie , Pliske Michelle , Superfine Richard , Taylor Russell 
Published: July 2020

Abstract
Repair of damaged or incorrectly matched DNA is essential to the survival of all organisms. Consequently cells have devised a plentitude of pathways for repair. We have been investigating the mechanisms of mismatch repair and base excision repair. Both of these repair processes involve a large number of proteins that interact with one another as well as with DNA. Our long-term goal is to assemble complexes that are fully functional for DNA repair and to image the process of DNA repair. In addition, we wish to i) determine the stoicheometry of binding of the protein complexes to each other and to DNA, ii) monitor conformational changes due to substrate binding, iii) measure physical properties of DNA and the complexes. To accomplish this end, we have endeavored to improve techniques for solution imaging as well as those for data analysis. In this presentation I will discuss data on the stoicheometry of binding in several protein complexes and data on the physical properties of DNA.
To measure the physical properties of DNA, we utilize a nanoManipulator, a modified Scanning Force Microscope with a novel, user-friendly interface that allows easy and controlled manipulation of nanometer-sized samples.
Structural Forces in Biomolecules
Authors: Rief Matthias , Oesterhelt Filipp , Clausen-Schaumann Hauke , Gaub Hermann E 
Published: July 2020

Abstract
The high spatial resolution and the force sensitivity of the Atomic Force Microscope have made it possible to perform mechanical experiments with single molecules. These experiments give direct access to the forces that stabilize biomolecule structure. In a variety of examples we show how different molecular interactions determine the mechanical stability of polysaccharides, proteins, DNA and other biomolecules.
Under the influence of a stretching force of around 750 pN the polysaccharide dextran undergoes a transition into a stretched conformation during which bond angles flip into a new conformation. Molecular dynamics simulations corroborated this conformational change.
Proteins fold into compact domains. Especially for structural proteins the mechanical stability of these domains is of importance. We show that the immunoglobulin and fibronectin III domains of the muscle protein titin exhibit exceptionally high unfolding forces (150-250 pN) when stretched at speeds of normal muscle operation (Fig. 1).
3d Confocal Microscopy and Image Analysis for Measurement of Genetic Instability
Authors: Ortiz de Solorzano C , Chin K , Knowles D , Jones A , Garcia E , Gray JW , Lockett SJ 
Published: July 2020

Abstract
Solid tumors frequently contain cells that are heterogeneous in the copy number of DNA loci. This fact implies the existence of genetic instability, which may be associated with disease aggressiveness. Accurate measurement of this phenomenon requires analysis of intact nuclei within their natural tissue context. We perform these measurements by preparing &gt;30μm thick tissue sections, labeling them with fluorescent labels for total DNA and for specific DNA loci using fluorescence in situ hybridization (FISH) which retain the transparency of the tissue and acquiring 3D images of the tissue using confocal microscopy (figure 1). In this study, we combined automated 3D image analysis (IA) algorithms for segmenting individual nuclei based on the total DNA stain1 and for segmenting the punctuate FISH signals of DNA loci. This enables us to efficiently enumerate the copy number of specific DNA loci in individual cells and as a function of the cell's location in the tissue.
Monitoring of Cell Surface Movement at the Erythrocyte’s Edge By Scanning Phase Contrast.Microscopy
Authors: Bitler Arkady , Barbul Alexander , Korenstein Rafi 
Published: July 2020

Abstract
We explored the ability of a novel method of nano-scale movement detection to analyze the effects of chemical crosslinking and thiol reduction on the fluctuations of the human erythrocyte membrane. The method employs line images of light intensity distribution across the red blood cell, obtained by laser scanning phase contrast microscope. The essential feature of these images is a noiseless region corresponding to edge scene. This enables- one to carry out very accurate fitting procedure between the theoretical intensity distribution and the experimental one. One of the free parameters of fitting is the edge position. Measuring line scan intensity distributions with a certain sampling rate and defining the edge positions in consequent moments of time, yields the time-dependent displacement of cell's edge with up to nanometer scale precision.
The significant feature of the suggested procedure is that it implicitly takes into account the halo effect.
Early “Events” in Hiv Infection and Hiv-Associated Neoplasia
Authors: Brian Herndier 
Published: July 2020

Abstract
The course of HIV infection necessarily involves the initial establishment of the virus in a receptive host environment. HIV disease involves active intracellular replication of the virus and spread of the virus from the initial compartment of the infection. Finally, from the virus’ perspective _ virions must enter a compartment suitable for eventual host-host transmission. In the vernacular of HIV epidemiology this implies some sort of “exchange of bodily fluids”.
Recently, our research focus has been on tracking HIV during the early phases of infection. The goal is to piece together a full chronology of the disease at the tissue level. The emphasis will be on changes in lymphoid architecture that might ultimately be important in the pathogenesis of AIDS malignancies and offer insight into the dysfunctional aspects of immunity in the setting of retroviral infection. Because HIV disease often ultimately features a severe immunodeficiency, other pathogens by necessity play a role in shaping the “visible” immune response.
Aids/Opportunistic Infections
Authors: Guccion J 
Published: July 2020

Abstract
Use of TEM in the diagnosis of opportunistic infections in AIDS patients is indicated in three situations. First, when an opportunistic infection is suspected, but an infectious agent is not visible in tissue sections studied by light microscopy (LM). This situation is illustrated by the following case.(1) A 33-year-old man with AIDS presented with fever, nightsweats, generalized lymphadenopathy, and a 30 lb. weight loss. An inguinal lymph node biopsy was performed. There was no consensus as to the diagnosis among the pathologists who studied H&E sections of the biopsy. An obscure infectious disease, a B-cell lymphoma with amyloid stroma, and possibly Hodgkin's disease were the major considerations. TEM study revealed unexpected clusters of small, pleomorphic, coccobacillary bacteria in vascular walls typical of cat scratch disease. These bacteria were later further identified by polymerase chain reaction as belonging to the genus Rochalimaea(now Bartonella), an important cause of cat scratch disease.
Aids-Associated Viral Infections
Authors: Miller Sara E 
Published: July 2020

Abstract
Infection with human immunodeficiency virus (HIV) eventually causes a profound decrease in the body's ability to eradicate or control infections with microorganisms, including viruses. Some infections in AIDS patients are due to common organisms which are of little significance in immunocompetent individuals. Other organisms can be harbored continuously, occasionally causing disease, but normally being suppressed after a heightened immune defense; in AIDS patients, these infections can be life-threatening. Further, practices that predispose to HIV infection also permit entry of other organisms, such as hepatitis and herpesviruses. Electron microscopy is beneficial as an adjunct to other modalities for viral detection. Methods for identifying viruses, both in fluids by negative staining and in tissues by thin sectioning, have been published. Some viral pathogens, including HIV itself, are best documented by other means.
HIV has been demonstrated by EM in infected individuals, but because it destroys and makes scarce the cells for which it has an affinity, it is difficult to find them.
Permeability Oxygen Through Endothelium By Time-Resolved Fluorescence Microscopy : Influence.of Plasma Viscosity on Tissue Hypoxia.
Authors: Dominique Dumas , Véronique Latger , Viriot Marie L , Stoltz Jean F 
Published: July 2020

Abstract
Vascular endothelial cells (EC) forms a continuous monolayer, a selective barrier that coats the inner surface of the vascular system, representing the primary anatomical site between blood and tissue. Under closed conditions (shear stress, hypoxia-reoxygenation..), EC are activated and the level of adhesion molecules (ICAM-1) expression increased. A technique of fluorescence quenching by oxygen in cell membrane was used to study molecular transport processes on a larger scale1-4. Collisional fluorescence quenching is described by the Stern-Volmer equation : τ0 / τ = 1 + kd.PO2 where τ0 and τ are respectively the excited state lifetimes in the absence and in the presence of oxygen, Kd the quenching dynamic constant and PO2 the oxygen partial pressure. The main purpose of the present study was to investigate the relation a) between the plasma viscosity and PO2 across human EC monolayer by Time-Resolved Fluorescence Microscopy (TRFM5-6 ) between the PO2 calculated and the level of ICAM-1 expression by flow cytometry (FCM)7 and Conventional Optical Scanning Microscopy (COSM8).
In Vivo Characterization of Cardiac Tissue Defects Associated With Pdgfrα Gene Deletion In the Patch Mouse
Authors: Thielen T , Terracio L , Borg TK , Price RL 
Published: July 2020

Abstract
The active form of platelet derived growth factor (PDGF) is a polypeptide dimer of which there are three isoforms: PDGF-AA, PDGF-BB, and PDGF-AB. Furthermore, two types of PDGF receptors also exist: PDGFRα and PDGFRβ. The β-receptor binds only the PDGF-B chain with high affinity, while the αreceptor can bind either PDGF-A or -B chains. Both PDGF ligands and their receptors have been linked to such cellular responses as mitogenisis, cell migration, chemotaxis, adhesion and differentiation in a variety of cell types.
Several studies have reported fetal cardiac abnormalities associated with disruption of PDGF and its receptors. In spontaneous mutants lacking the PDGF α-receptor (Patchmice), fetal hearts are generally dilated and exhibit valve and outflow tract defects. Similar defects are observed in normal embryos injected with antibodies to block the functioning of the PDGF-A chain. Disruption of PDGF-B function results in ventricular and atrial dilation, reduction of the ventricular wall, and hyper-trabeculation.
Biological Relevancy of Quantitative Analysis of Adherence Receptors on Polymorphonuclear.Neutrophil by Flow Cytometry and Optical Scanning Microscopy..
Authors: Dumas Dominique , Latger Véronique , Stoltz Jean F 
Published: July 2020

Abstract
Leukocytes adherence receptors are the basis of cells interactions1. Flow cytometry (FCM) makes it possible to assess a characterization of the activation level of a given cellular population by receptor quantifying2. That technique, however does not integrate at the same time, all others factors of leucocyte adhesive phenotype regulation, as spatial distribution and molecular conformation. Our study consisted in exploring the main adhesion receptors (CD62L, CDllb/CD18) on the surface of Polymorphonuclear Neutrophils (PMN) that were prepared under identical conditions and simultaneously analyzed by FCM and Conventional Optical Scanning Microscopy/Deconvolution3 (COSM). Methods: PMN cells from whole blood were obtained using Polymorphprep™. Isolated PMN (105 cells /ml) were incubated with Tumor Necrosis Factor (TNFα, 100 UI/ml) at 37°C for one hour. Quantification of cell surface molecules was assessed according to the quantitative indirect immunofluorescence3 method using QIFIKIT® (Dako, France).
The Structure of Maize Streak Virus: Are Two Heads Better Than One?
Authors: Zhang W , Olson N H , Chipman P R , McKenna R , Baker T S 
Published: July 2020

Abstract
The geminiviruses are a group of plant DNA viruses characterized by having one or two copies of a single-stranded, circular DNA genome and frequent occurrence of geminate, quasi-isometric particles as observed by transmission electron microscopy. The Geminiviridaefamily is classified into three genera (Mastrevirus, Curtovirus and Begomovirus)based on the number of DNA components, the plant hosts, and the transmission vectors. Maize streak virus (MSV), the type member of the Mastrivirusgenus, is transmitted by the leafhopper and infects Gramineaespecies. Wheat dwarf virus, Digitaria streak virus, and Chloris striate mosaic virus (CSMV) are examples of other members of the Mastrivirusgenus. The Nigerian strain of MSV (MSV-N) contains one copy of a singlestranded, circular DNA molecule (2687 nucleotides). Two protein products, VI and V2, are coded by the MSV-N genome.2 V2 (244 amino acids) is the only coat protein found in virions.
Ultrastructural Diagnosis of Whipple& Disease at Autopsy
Authors: Siew S , Newton B 
Published: July 2020

Abstract
Whipple's disease is a rare systemic disorder with the intestinal tract being the major site of predilection. The characteristic histologic features are the infiltration of large numbers of macrophages, which have a clear or vacuolated cytoplasm. In his original documentation of “a hitherto underscribed disease”, Whipple interpreted the vacuo lation to be due to deposits of fat and fatty acids and gave the name “interstinal lipodystrophy” to the pathology. In this report, Whipple did describe the presence of rod shaped organisms in Levaditi (reduced silver) stained preparations, but, it was not until a half century later, that the definitive presence of intracellular organisms was demonstrated by means of transmission electron microscopy. Further investigations showed that the organism is a Gram positive actinomycete, which has been designated as Tropheryma whippelii.
We report the case of a 72 year old woman, who was admitted with the chief complaints of abdominal cramps and diarrhea.
Centrosome and Centriole Abnormalities During Cancer In the Transgenic Adenocarcinoma Mouse Prostate (Tramp) Model
Authors: Schatten H , Wiedemeier A , Taylor M , Lubahn D , Greenberg N M , Besch-Williford C , Rosenfeld C , Day K , Ripple M 
Published: July 2020

Abstract
Centrosome abnormalities and abnormal mitotic formations have been shown in human breast cancer tissue and in LNCaP and DU145 prostate cancer cells in culture. Here we report on abnormal centrosome and centriole organization in the transgenic adenocarcinoma mouse prostate (TRAMP) model and on the implications for abnormal cell divisions, genomic instability, and apoptosis. Centrosomes are microtubule organizing centers which assemble bipolar spindles in normal cells. In cancer, centrosomes cause the formation of mono-, tri-, and multipolar mitoses which will separate chromosomes unequally during cell division.
We investigated the occurence of abnormal mitoses in TRAMP tissue in different stages of cancer progression using transmission electron microscopy (TEM). Advanced stages of prostate cancer are characterized by multiple abnormal mitoses ranging from tripolar to unusual multipolar formations. In addition, apoptotic bodies are abundant which may indicate that multipolar mitoses will lead to cell death or apoptosis.