bluuebunny/crossref_metadata_2025 huggingface dataset:
Influence and sensitivity analysis of thermal parameters on temperature field distribution of active thermal insulated roadway in high temperature mine
Authors: Yao Weijing , Pang Jianyong , Ma Qinyong , Lyimo Happiness
Published: July 2020

To study active heat insulation roadway in high temperature mines, the typical high temperature roadway of − 965 m in Zhujidong Coal Mine of Anhui, China, is selected as prototype. The ANSYS numerical simulation method is used for sensitivity analysis of heat insulation layer with different thermal conductivity and thickness, as well as surrounding rock with different thermal conductivity and temperature on a heat-adjusting zone radius, surrounding rock temperature field and wall temperature. The results show that the heat-adjusting zone radius will entirely be in the right power index relationship to the ventilation time. Decrease in thermal conductivity and increase in thickness of insulation layer can effectively reduce the disturbance of airflow on the surrounding rock temperature, hence, beneficial for decreasing wall temperature. This favourable trend significantly decreases with ventilation time, increase in thermal conductivity and temperature of surrounding rock, heat-adjusting zone radius, surrounding rock temperature field, and wall temperature. Sensitivity analysis shows that the thermal physical properties of surrounding rock determine the temperature distribution of the roadway, hence, temperature of surrounding rock is considered as the most sensitive factor of all influencing factors. For the spray layer, thermal conductivity is more sensitive, compared to thickness. It is concluded that increase in the spray layer thickness is not as beneficial as using low thermal conductivity insulation material. Therefore, roadway preferential consideration should be given to the rocks with low temperature and thermal conductivity. The application of the insulation layer has positive significance for the thermal environment control in mine roadway, however, increase in the layer thickness without restriction has a limited effect on the thermal insulation.
David Stow: Christian educator in nineteenth century Scotland
Authors: McKinney Stephen J.
Published: July 2020

The educational work of David Stow evolved in three phases. He established a Sabbath school and helped to introduce both infant schooling and teacher training in Glasgow, Scotland in the nineteenth century. He helped to establish the Glasgow Normal Seminary and later he joined the Free Church of Scotland Normal Seminary. Stow was a committed Presbyterian Christian, and this motivated him and was at the centre of all of the three phases of his educational work. He was dedicated to the school education of the poor, similar to other educators of his time. He understood this mission to the poor as a means to rescue them from the corrupting influences in their urban settings. The corrupting influences would be replaced, however, by social control and the promotion of Christianity. This article presents an examination of the close links between his strongly held Christian beliefs, Christian worldview and his vision of schooling and teacher preparation.
Discussion of “The Market for Reviews: Strategic Behavior of Online Product Reviewers with Monetary Incentives”
Authors: Ressi Anna
Published: July 2020

In this note, I discuss the article of Dorner et al. who experimentally study the issue of generating high-quality online product reviews under two different incentive schemes. I first classify their work in the existing literature on marketing and information systems and highlight their contribution. I then argue that the existence of cognitive dissonance costs serve as a reasonable explanatory factor for their main results. Two further critical issues warn against the limited generalizability of the present study to the real review market and ability to provide practical implications.
The Way Forward in Mindfulness and Sustainability: a Critical Review and Research Agenda
Authors: Thiermann Ute B. , Sheate William R.
Published: July 2020

The ecological crisis demands new strategies to rapidly transform our society into a more sustainable one. A growing amount of research points towards the potential of mindfulness to help transform people’s motivations for sustainability. This article reviews 30 years of research in mindfulness and sustainability and disentangles theoretical knowledge from empirical evidence. We identified six leading theoretical links between mindfulness and sustainability which find backing in empirical work: reduced automaticity, enhanced health and subjective well-being, greater connectedness with nature, improved pro-sociality, recognition of intrinsic values and openness to new experiences. Many of the studies involve considerable methodological caveats, most importantly a lack of mindfulness practice indicators and environmental impact measures. To reach the point where policy makers could embrace mindfulness-based policies to promote societal well-being and sustainability, the research must go beyond the present focus on correlative research. The proof of causality posits the greatest challenge for the next decade of research. Inspired by principles from policy evaluation, we propose a research agenda that offers direction for collaborative efforts and innovative interdisciplinary study designs in a logical model: (how) does the practice of mindfulness contribute to individual behaviour change and (how) does this individual change translate into societal change?
On the Computational Derivation of Bond-Based Peridynamic Stress Tensor
Authors: Fallah Arash S. , Giannakeas Ilias N. , Mella Rizgar , Wenman Mark R. , Safa Yasser , Bahai Hamid
Published: July 2020

The concept of ‘contact stress’, as introduced by Cauchy, is a special case of a nonlocal stress tensor. In this work, the nonlocal stress tensor is derived through implementation of the bond-based formulation of peridynamics that uses an idealised model of interaction between points as bonds. The method is sufficiently general and can be implemented to study stress states in problems containing stress concentration, singularity, or discontinuities. Two case studies are presented, to study stress concentration around a circular hole in a square plate and conventionally singular stress fields in the vicinity of a sharp crack tip. The peridynamic stress tensor is compared with finite element approximations and available analytical solutions. It is shown that peridynamics is capable of capturing both shear and direct stresses and the results obtained correlate well with those obtained using analytical solutions and finite element approximations. A built-in MATLAB code is developed and used to construct a 2D peridynamic grid and subsequently approximate the solution of the peridynamic equation of motion. The stress tensor is then obtained using the tensorial product of bond force projections for bonds that geometrically pass through the point. To evaluate the accuracy of the predicted stresses near a crack tip, the J-integral value is computed using both a direct contour approximation and the equivalent domain integral method. In the formulation of the contour approximation, bond forces are used directly while the proposed peridynamic stress tensor is used for the domain method. The J-integral values computed are compared with those obtained by the commercial finite element package Abaqus 2018. The comparison provides an indication on the accurate prediction of the state of stress near the crack tip.
Selective end-to-end data-sharing in the cloud
Authors: Hörandner Felix , Ramacher Sebastian , Roth Simon
Published: July 2020

Cloud-based services, such as Google Drive, Dropbox, or Nextcloud, enable easy-to-use data-sharing between multiple parties, and, therefore, have been widely adopted over the last decade. Nevertheless, privacy challenges hamper their adoption for sensitive data: (1) rather than exposing their private data to a cloud service, users desire end-to-end confidentiality of the shared files without sacrificing usability, e.g., without repeatedly encrypting when sharing the same data set with multiple receivers. (2) Only being able to share full (authenticated) files may force users to expose overmuch information if the data set has not been exactly tailored to the receiver’s needs at issue-time. This gap can be bridged by enabling cloud services to selectively disclose only relevant parts of a file without breaking the parts’ authenticity. While both challenges have been solved individually, it is not trivial to combine these solutions and maintain their security intentions. In this paper, we tackle this issue and introduce selective end-to-end data-sharing by combining ideas from proxy re-encryption (for end-to-end encrypted sharing) and redactable signature schemes (to selectively disclose a subset of still authenticated parts). We overcome the issues encountered when naively combining these two concepts, introduce a security model, and present a modular instantiation together with implementations based on a selection of various building blocks. We give an extensive performance evaluation of our instantiation and conclude with example applications.
How polyurethane can be used in today's manufacturing industry
Authors: Brito Adrian
Published: July 2020

Many manufacturers assemble products with polyurethane, but this ubiquitous material is also used in the process of making things. Because polyurethane has such unusual chemistry, it is often used during the production of products that contain polyurethane.

Polyurethane is made during a chemical process where a polyol interacts iso- or diisocyanate with additives and catalysts. Different reactions create polyurethanes that take different forms like foams, sealants, adhesives, or other flexible solids. Because of the different forms, polyurethanes can be used in surprising ways, and through several stages of manufacturing.
‘Mutatio Sub Pressura’: An Exploration of the Youth Policy Response to the Syrian Refugee Crisis in Germany
Authors: SICHLING FLORIAN
Published: July 2020

This article explores the response of the child welfare system in Germany to the recent refugee crisis. Drawing on administrative data and qualitative interviews with administrators, front-line workers and refugee youth in Nuremberg, the article provides a contextualized account of how the crisis led to the collapse of established bureaucratic procedures, new forms of interagency collaboration and a flexible distribution of responsibilities and tasks. Combining a street-level bureaucracy (SLB) perspective with insights from the literature on crisis and policy change, the analysis shows how the responses of front-line workers effectively altered the content of services, introduced new actors and expanded the professional capacity of the local child welfare system. On a broader level, the findings indicate that front-line practice is not merely guided by policy mandates, but also responds to situational and institutional circumstances. For the child welfare system in Nuremberg, the findings raise important questions about the extent to which aspects of the crisis response will remain a part of the service delivery process moving forward, and whether the recent experience will better prepare them for future crises.
Using a developmental perspective to examine the moderating effects of marriage on heavy episodic drinking in a young adult sample enriched for risk
Authors: Cho Seung Bin , Smith Rebecca L. , Bucholz Kathleen , Chan Grace , Edenberg Howard J. , Hesselbrock Victor , Kramer John , McCutcheon Vivia V. , Nurnberger John , Schuckit Marc , Zang Yong , Dick Danielle M. , Salvatore Jessica E.
Published: July 2020

Many studies demonstrate that marriage protects against risky alcohol use and moderates genetic influences on alcohol outcomes; however, previous work has not considered these effects from a developmental perspective or in high-risk individuals. These represent important gaps, as it cannot be assumed that marriage has uniform effects across development or in high-risk samples. We took a longitudinal developmental approach to examine whether marital status was associated with heavy episodic drinking (HED), and whether marital status moderated polygenic influences on HED. Our sample included 937 individuals (53.25% female) from the Collaborative Study on the Genetics of Alcoholism who reported their HED and marital status biennially between the ages of 21 and 25. Polygenic risk scores (PRS) were derived from a genome-wide association study of alcohol consumption. Marital status was not associated with HED; however, we observed pathogenic gene-by-environment effects that changed across young adulthood. Among those who married young (age 21), individuals with higher PRS reported more HED; however, these effects decayed over time. The same pattern was found in supplementary analyses using parental history of alcohol use disorder as the index of genetic liability. Our findings indicate that early marriage may exacerbate risk for those with higher polygenic load.
Negative affect reactivity to stress and internalizing symptoms over the transition to college for Latinx adolescents: Buffering role of family support
Authors: Anderson Samantha F. , Sladek Michael R. , Doane Leah D.
Published: July 2020

Affect reactivity to stress may play a role in the development of internalizing symptoms during the college transition, a critical developmental juncture for Latinx adolescents, the largest ethnic minority group on college campuses. This study examined whether affect reactivity during high school is associated with internalizing symptoms in college and explored two potential protective factors, perceived family and peer support. Participants were 209 Latinx adolescents (Mage = 18.10; 64.4% female) who completed standard surveys and four diary assessments per day over 7 days (N > 4,500 momentary observations). First, to measure affect reactivity, we assessed whether perceived stress was associated with negative affect at the momentary level during high school (senior year). Second, we tested whether affect reactivity predicted internalizing symptoms during the first year of college. Third, we tested whether perceived family or peer support buffered the negative consequences of affect reactivity. Results indicated statistically significant within- and between-person associations between stress and negative affect. Moreover, affect reactivity significantly predicted depressive, but not anxiety, symptoms. Buffering was found for family, but not peer, support. Findings extend previous research by detecting associations between momentary affect reactivity and internalizing symptoms during a sociocultural shift in Latinx adolescents’ lives and have implications for culturally appropriate programs to prevent depressive symptoms.
A qualitative analysis of infant and young child feeding practices in rural Rwanda
Authors: Dusingizimana Theogene , Weber Janet L , Ramilan Thiagarajah , Iversen Per O , Brough Louise
Published: July 2020

Objective:

To explore and gain an in-depth understanding of the factors influencing child feeding practices among rural caregivers in Rwanda.

Design:

In-depth semi-structured qualitative interviews were conducted. Purposive sampling was used to recruit participants. Interviews were audio-recorded, transcribed verbatim and coded. Data were analysed inductively using thematic analysis.

Setting:

Rutsiro District, Western Province, Rwanda.

Participants:

Participants included twenty-four mothers (median age 32 years) with children 6–23 months old.

Results:

We identified five key themes: (i) breast-feeding practices and role in food supply; (ii) family v. children’s food preparations; (iii) food classification systems and their influence on child feeding decisions; (iv) child feeding during diarrhoeal episodes and (v) influence of poverty on child feeding practices and child care.

Conclusions:

Mothers’ infant and young child feeding decisions are informed by information both from health workers and from traditional/own knowledge. Navigating through this information sometimes creates conflicts which results in less than optimal child feeding. A nutrition educational approach that is cognisant of maternal perceptions should be employed to improve child feeding practices. Efforts to improve child feeding practices must be complemented by programmes that enhance household economic opportunities and access to foods.
STEM Cells and Liver Carcinogenesis: Contributions of Light, Confocal and Electron Microscopy
Authors: Novikoff P M , Yam A
Published: July 2020

Three cell types not previously described were revealed by the application of several microscopic procedures in combination with cytochemistry and irnmunocytochemistry in the livers of rats treated according to the Solt et al carcinogenesis protocol. This protocol consists of the administration of an initiating carcinogen (diethynitrosamine), a mitoinhibitory carcinogen, (acethylaminofluorene) and a growth stimulus (partial hepatectomy) (1). Two of the cell types were found in intrahepatic bile ductules and one within the connective tissue stroma surrounding the ductules. These findings have implications for understanding the cell lineage pathways that operate in an experimental rodent hepatocarcinogenesis system in which hepatocyte regeneration is inhibited and in which preneoplastic nodules and hepatomas develop. Our previous studies have determined some of the enzymatic, antigenic and structural properties of these cell types and their interrelations to each other, to parenchymal hepatocytes and to preneoplastic nodules (2).

Proliferation of bile ductule cells occurs early (24-48 hrs) after the partial hepatectomy step of the protocol with extensive branching of the ductules into the hepatic parenchyma.
The Use of Semi-Thick Sections to Evaluate the Association Between a Species of Theileria and the Erythrocyte Membrane
Authors: Droleskey R E , Craig T M , Roussel A J , Holman P J , Stanker L H
Published: July 2020

Relatively benign or mildly pathogenic strains of bovine Theileria, an intraerythrocytic protozoan parasite, have been reported in many parts of the world including T. mutans in Africa, T. buffeli in Australia, T. orientalis in Britain, and a Theileria sp. from the Southwestern United States (US). Although the Theileria found in the US has not been specifically speciated, it has been referred to as T. mutans-like and as T. orientalis (USA). Although cattle in the US infected with these Theileria spp. usually have a circulating parasitemia of less than 1% and are asymptomatic, recently an animal suffering from severe anemia was admitted to the Large Animal Clinic at Texas A&M University with a circulating parasitemia of over 50%.

Parasites in Giemsa stained blood films were pleomorphic in shape, with some parasites apparently connected to the erythrocyte membrane (Fig. 1) by structures which appeared similar to the bar structure found within eland (Taurotragus oryx) erythrocytes parasitized by T. taurotragi. Examination by TEM revealed that in addition to the main body of the parasite, parasitized erythrocytes contained parasites which possessed cytoplasmic extensions and an interaction between the parasite and the erythrocyte membrane which involved invaginations of the erythrocyte membrane which appeared to be surrounded by parasite cytoplasm (Fig. 2).
Use of GFP Fusions to a Microtubule Motor Protein to Analyze Spindle Dynamics in Live Oocytes and Embryos of Drosophila
Authors: Endow S A , Komma D J
Published: July 2020

Ncd is a kinesin-related microtubule motor protein of Drosophila that plays essential roles in spindle assembly and function during meiosis in oocytes and mitosis in early embryos. Antibody staining experiments have localized the Ned motor protein to spindle fibers and spindle poles throughout the meiotic and early mitotic divisions, demonstrating that Ncd is a spindle motor.

We have made ncd-gfp gene fusions with wild-type and S65T gfp and expressed the chimaeric genes in Drosophila to target GFP to the spindle. Transgenic Drosophila carrying the ncd-gfp gene fusions in an ncd null mutant background are wild type with respect to chromosome segregation, indicating that the Ncd-GFP fusion proteins can replace the function of wild-type Ncd. The Ncd-GFP fusion proteins in transgenic Drosophila are expressed under the regulation of the native ncd promoter.

Analysis of live Drosophila oocytes and early embryos shows green fluorescent spindles, demonstrating association of Ncd-GFP with meiotic and mitotic spindles. In mitotic spindles, Ncd-GFP localizes to centrosomes (Fig. 1a) and spindle fibers (Fig. 1b).
A Nonradiometric Detection System For the Rapid and Easy Detection of Oxytocin Oligonucleotide Probes in In Situ Hybridization
Authors: Tyler MC , Mayer PC
Published: July 2020

We describe the easy and rapid detection of oxytocin oligonucleotide probes in in situ hybridization using a biotinyl tyramide amplification system (TSA).

There are several some instances where related proteins have sequence homology so great that only oligonucleotide probes will allow one to distinguish between their mRNAs. Vasopressin and oxytocin are such a pair. Traditional in situ hybridizationusing 35S labeled probes allows the specific detection of oxytocin mRNA.See FIG. 1.

Nonradiometnc detection of oligonucleotide probes can be very difficult since the amount of labeling possible is limited by the small size of the probe. Traditional nonradiometric detection of a 30-mer biotin-labeled oxytocin probe with streptavidin-HRP followed by DAB detection proved essentially negligible. See FIG. 2.

A novel tyramide amplification system (TSA) was used to increase the detection of the oxytocin probe signal. Most of the protocol was unchanged from the standard nonradioactive methodology. The biotin-labeled probe was hybridized overnight as usual. Stringency washes were also done as usual the next morning.
Immunogold-Silver Staining (IGSS) of (NCP and CP) BVDV Infected Subcellular Fraction Bands
Authors: Hearne CE , Johnson DL , Van Campen H
Published: July 2020

Pre-embedding immunogold-silver (IGSS) techniques are useful to localize antigens in cell monolayers and agarose embedded cell suspensions for transmission electron microscopy. Procedural centrifugations, however, present a challenge when attempting to localize antigens in subcellular fractions. Using a Beckman Airfuge Ultracentrifuge to concentrate the subcellar fraction bands and resuspending the organelles in agarose simplifies IGSS processing and resin embedding procedures.

Control bovine turbinate (BT), and BT cells infected with cytopathic (cp NADL) and non-cytopathic (ncp NY-1) strains of bovine viral diarrhea virus (BVDV) were fractioned according to Bienz et al (1992). Bands containing membrane vesicles (Fig 2) were collected and each fraction band was pelleted at 169,000g for 20 min using an A-95 fixed angle rotor in a Beckman Airfuge Ultracentrifuge. Each fraction pellet was resuspended in 50μl of 30% agarose, solidified, and trimmed to < lmm. IGSS procedures were carried out according to Nanoprobes, Inc., Stoney Brook, NY, and Hearne & Van Campen (1996).
New Single Molecule Approaches to Genomic Analysis: Optical Mapping
Authors: D.C Schwartz , T Anantharaman , W Cai , V Clarke , S Delobette , E Dimalanta , J Edington , J Giacalone , C Hiort , X Hu , E Huff , J Jing , Z Lai , E Lee , B Mishra , J.R Murti , B. Porter , R Qi , R Rabbah , A Ramanathan , J Reed , A Samad , A Shenker , Y Skiadas , K Tankhoveya , W Wang , J Lin
Published: July 2020

Current molecular biological approaches were developed primarily for characterization of single genes, not entire genomes, and, as such, are not ideally suited to analysis of complex traits and population-based molecular genetics. Despite rapid progress in the human genome project effort, there is little doubt that radically new conceptual approaches are needed before routine whole genome-based analyses can be undertaken by both basic research and clinical laboratories.

Physical mapping of genomes, using restriction endonucleases, has played a major role in the identification and characterizing various loci, for example, by aiding clone contig formation and by characterizing genetic lesions. Restriction maps provide precise genomic distances, unlike ordered sequence-based landmarks such as Sequence Tagged Sites (STSs), that are essential for optimizing the efficiency of sequencing efforts, and for determining the spatial relationships of specific loci. When compared to tedious hybridization-based fingerprinting approaches, ordered restriction maps offer relatively unambiguous clone characterization that is useful in contig formation, establishment of minimal tiling paths for sequencing, and preliminary characterization of sequence lesions.
Super-Thin Serial Sectioning for High-Resolution 3-D Reconstruction of Cellular Structures
Authors: Mastronarde D N , Ladinsky M S , Mcintosh J R
Published: July 2020

We are developing techniques for obtaining the thinnest possible serial sections of biological specimens. Our goal is to produce not just an occasional very thin section but large numbers of 5-15 nm serial sections suitable for 3-D reconstruction. We have worked out conditions that allow us routinely to cut serial sections ˜15 nm thick, and have achieved ribbons of sections with an average thickness of only 11 nm.

We have worked with the Leica Ultracut S and Ultracut UCT microtomes, which have proven to be exceptionally stable instruments, capable of very regular advance between cutting strokes. The resulting low variability in section thickness is essential for serial sections thinner than 15 nm. However, these machines have an inherent forward drift that increases the thickness of sections cut soon after a block has been mounted and prepared for cutting. This drift is initially 50-100 nm/min, but decreases to only 10-20 nm/min if the microtome is allowed to cycle for 0.5—1.5 hours.
Two Microtubule Organizing Centers are Anchored in the Cortex Prior to Mammalian Oocyte Maturation
Authors: Calarco Patricia G
Published: July 2020

Oocyte meiotic maturation involves complex processes of nuclear breakdown, spindle formation, and organelle movement necessary for successful fertilization and early development. Yet these take place in the mouse without the aid of centrioles; instead the spindle is organized by a number of microtubule organizing centers (MTOC).Multiple MTOC are seen by fluorescence microscopy to migrate from the cortex to the nucleus (germinal vesicle; GV) during the first 30 min of maturation. However, EM has not revealed the expected ultrastructure of MTOC known from previous studies. New information from the present study sheds light on MTOC number, location and ultrastructure prior to and during very early maturation.

Maturation occurs in vitro when oocytes are released from ovarian follicles into culture, but is blocked by dibutyrl cAMP or IBMX (3-isobutyl-l-methyl xanthine; Sigma). MTOC were studied after 0-2 h in culture medium; IBMX medium (0.2 mM); an inhibitor of MT (nocodazole, lμM); or MF (cytochalasin, 5 μg/ml) by fluorescent confocal microscopy (CM; Biorad 600) or standard EM.
Presentation of Idented Acini in Rat Lactating Breast: A Histochemical and Ultrastructural Study
Authors: Umemura S , Hasegawa H , Tsutsumi Y , Itoh Y , Itoh J , Tokunaga M , Watanabe K , Osamura R Y
Published: July 2020

We have previously reported that epithelial cells appear to be clustered in the perilobular stroma of the human lactating breast', that phenomenone has not beendocumented well in the literature. The present study is aimed at to clarify the nature and characteristics of the clustered-epithelial cells in relation to basement membrane, epithelial cell death and myoepithelial cells.

We studied the mammary gland of Wister female rats in various stages of resting, pregnant and lactating phase histochemically and electron microscopically. Basement membrane was detected by immunohistochemically (indirect peroxidase method) on 4% paraformaldehyde (PFA)-fixed frozen section using anti type rv collagen (goat, Southern Biotechnology Assoc. Inc. Birmingham, AL, USA) and electron microscopcally. Apoptotic cell death was shown by in situend labeling method on formalin-fixed paraffin-embedded section. The myoepithelial cells were observed by alkaline phophatase Azo dye method on frozen section, and by immunohistochemical staining for actin (smooth muscle) (clone; 1A4, Sigma Chemical Co. St Louis, MO, USA).
Texture Analysis and Classification of Coronary Plaque in Intravascular Ultrasound
Authors: Dixon K J , Vince D G , Cothren R M , Cornhill J F
Published: July 2020

Atherosclerosis is a degenerative arterial disease that leads to the gradual blockage of vessels due to plaque formation or acute ischaemic events such as plaque rupture. A thorough understanding of plaque morphology is necessary in the determination of factors underlying coronary artery disease. Intravascular ultrasound (IVUS) represents a diagnostic technique that provides tomographic visualization of coronary arteries. Ultrasound reflects sound at the interfaces between media of different acoustic refractive indices theoretically implying that various components within an ultrasound image should be distinguishable. The aim of this study is to classify plaque lesions using advanced digital image processing into the following categories: adventitia, media, fibrous, necrotic core, and calcified. Examination of plaque composition can yield valuable information necessary in determining the appropriate preventative and mechanical interventions.

Diseased samples were obtained from excised human coronary arteries at autopsy. Intravascular ultrasound images were acquired using an HP SONOS clinical IVUS imaging system and 3.5 French 30 MHz catheters.
Comparison of Precision XTEM Specimen Preparation Techniques for Semiconductor Failure Analysis
Authors: Amy Hunt C
Published: July 2020

The demand for TEM analysis in semiconductor failure analysis is rising sharply due to the shrinking size of devices. A well-prepared sample is a necessity for getting meaningful results. In the past decades, a significant amount of effort has been invested in improving sample preparation techniques for TEM specimens, especially precision cross-sectioning techniques. The most common methods of preparation are mechanical dimpling & ion milling, focused ion beam milling (FIBXTEM), and wedge mechanical polishing. Each precision XTEM technique has important advantages and limitations that must be considered for each sample.

The concept for both dimpling & ion milling and wedge specimen preparation techniques is similar. Both techniques utilize mechanical polishing to remove the majority of the unwanted material, followed by ion milling to assist in final polishing or cleaning. Dimpling & ion milling produces the highest quality samples and is a relatively easy technique to master.
Fast Cross-Sectioning Technique for Thin Films by Ultramicrotomy
Authors: Schubert-Bischoff Peter , Krist Thomas
Published: July 2020

The usual method to prepare specimen for transmission electron microscopy (TEM) with an ultramicrotome (UM) is to embed a small piece of the sample in a resin which needs between hours and days to harden. Then the resin is trimmed and finally the thin sections are cut. We developed a method to produce cross sections with an UM without embedding the sample. This leads to first TEM pictures in less then 30 minutes after the end of the thin film production.

We produce neutron mirrors which consist of metallic monolayers (figl) or multilayers (fig.2). The materials we use are mostly cobalt-iron alloys and silicon. The quality of the mirrors critically depends on the structural and hence also on the magnetic properties which are strongly influenced by the settings of the sputter parameters (plasma current, pressure of the working gas, substrate temperature, sputtering high voltage). To find out the best parameters for each purpose a quick analysing method is needed for a fast feedback
High Resolution Fesem Study of Au Particle Growth on TiO2
Authors: Cosandey F , Zhang L , Madey T E
Published: July 2020

Transition metals supported on oxides have important catalytic properties and are also used in chemical gas sensors for increasing sensitivity and selectivity. In order to understand growth and reactivity in the Au/TiO2 system, we have performed surface studies on a model system consisting of ultrathin, discontinuous Au films on TiO2 (110) single crystals. In this paper we are presenting results obtained by high resolution scanning electron microscopy (HRSEM) on the effects of substrate temperature and average Au thickness on particle size, density and coverage.

The TiO2 (110) single crystal surfaces used in this study were prepared in UHV using surface science tools followed by in-situ Au deposition for different substrate temperatures and for various film thicknesses. After deposition, the samples were transferred in air to the Field Emission Scanning Electron microscope (LEO 982 Gemini) for high resolution imaging.

Typical high resolution scanning electron microscopy (HRSEM) images of Au films deposited at 300 K are shown in Fig. 1 for two film thicknesses of 0.22 and 1.0 nm.
TEM Analysis of Defects in Simox Silicon-On-Insulator Material
Authors: Guss B , Seraphin S , Cordts BF
Published: July 2020

Silicon-on-Insulator is the leading technology for VLSI fast speed processors and low voltage applications. SIMOX (Separation by Implantation of Oxygen) is a subset of SOI with a high quality top silicon layer onto which VLSI circuitry is placed. SIMOX processing begins with a high energy, high current implantation of a large dose of O+ ions to penetrate the wafer’s surface to form the buried oxide and top silicon layers. This implantation creates numerous precipitates and a large damage region. Therefore a multi-step anneal is used to improve the quality of the top silicon layer by significantly reducing precipitate and dislocation densities, to create smooth interfaces, and to remove any ion residual damage. Using TEM, this study traces the defect formations through the various processing steps, with the objective to arrive at device quality.

The SIMOX wafers were implanted with an oxygen ion implant dose of 5xl017cm−2, and then subjected to multiple implantation and anneal steps, bringing the final oxygen ion dose to 1.5xl018cm−2[1].
Experiments on Foucault Imaging of Superconducting Fluxons
Authors: Yoshida T , Endo J , Harada K , Kasai H , Matsuda T , Beleggia M , Pozzi G , Tonomura A
Published: July 2020

The out-of-focus method has been successfully employed in the dynamical observation of superconducting fluxons. However, owing to the large defocus distance needed to image fluxons with enough contrast it turns out that their correlation with structural defects, better imaged at focus, is troublesome. Among the standard methods of Lorentz microscopy the Foucault technique is a good candidate for removing this drawback, since it generates phase contrast in the focused image by masking part of the transmitted beam by means of an aperture.

Therefore, simulations have been carried out both for one-dimensional fluxon models and more realistic two dimensional ones, with the result that enough contrast can be generated in the focused image in order to detect them. However, although these theoretical results suggest the feasibility of Foucault experiments, filling the gap between theory and practice is not an easy task, especially when considering the small angular deflections involved, of the order of 10−5 rad.
Simulation of the Spin Polarization Transfer of Electrons in a Solid
Authors: Kotera M , Tamura K
Published: July 2020

The electron spin polarization scanning electron microscopy (Spin-SEM) has been used to image the surface magnetic structures of magnetic materials in the order of nra scale. However, the sensitivity of the Spin-SEM so far used is very low. To improve the sensitivity, it is necessary to find the best condition for the electron detection system. The Mott polarimeter has commonly been used in the Spin-SEM. In the present study the performance of the Mott polarimeter is discussed. The geometrical configuration and the value of the post acceleration of secondary electrons to the detector have been experimentally determined or analized by a simple theoretical consideration. On the other hand, in the present study the condition to obtain the highest intensity and the highest signal contrast is seached by using an electron trajectory simulation in the Mott polarimeter. A series of electron scattering events and the electron energy loss in the target of the polarimeter is calculated, and not only the three dimensional scattering trajectory of electrons, but also the spin polarization transfer at every scattering event are traced in the target.
Beam-Broadening Effects in STEM/EDS Measurement of Radiation-Induced Segregation in High-Purity 304L Stainless Steel
Authors: Busby JT , Allen TR , Kenik EA , Zaluzec NJ , Was GS
Published: July 2020

Radiation-induced segregation (RIS) is the spatial redistribution of elements at defect sinks such as grain boundaries and free surfaces during irradiation. This phenomenon has been studied in a wide variety of alloys and has been linked to irradiation-assisted stress corrosion cracking (IASCC) of nuclear reactor core components. Therefore, accurate determination of the grain boundary composition is important in understanding its effects on environmental cracking. Radiation-induced segregation profiles are routinely measured by scanning-transmission electron microscopy using energy-dispersive X-ray spectroscopy (STEM-EDS) and Auger electron spectroscopy (AES). Because of the narrow width of the segregation profile (typically less than 10 nm full width at half-maximum), the accuracy of grain boundary concentration measurements using STEM/EDS depends on the characteristics of the analyzing instrument, specifically, the excited volume in which x-rays are generated. This excited volume is determined by both electron beam diameter and the primary electron beam energy. Increasing the primary beam energy in STEM/EDS produces greater measured grain boundary segregation, as the reduced electron beam broadening a smaller excited volume.
Dynamic Observation of Vortex Interaction with Pinning Centers Using Electron Waves
Authors: Tonomura Akira
Published: July 2020

Tiny magnetic vortices hold the key in practical applications of superconductors, since the dynamic behaviors of vortices at pinning centers determine the critical current. These vortices have become observable directly and dynamically by using a “coherent” field-emission electron beam: The magnetic lines of force of vortices can be quantitatively observed as contour fringes in an electron-holographic interference micrograph. The change in the vortex radius could actually be measured when the temperature of a superconducting thin film changed. Vortices were also dynamically observed in a Lorentz micrograph. Both vortices and defects in the thin film can be observed simultaneously with this method, though the defects image is blurred.

This paper reports the dynamic observation of vortices at defects when the applied magnetic field changes. A superconducting Nb thin film, set on a low-temperature stage, is tilted 45° to an incident beam of 300kV electrons (see Fig. 1), and an external magnetic field is applied in the horizontal direction. When an electron beam passes through the vortices, their magnetic fields deflect the electron beam. Therefore, when observed in the lower plane, a vortex can be viewed as a pair of black and white spots.
High-Resolution Observation of Si100-xVx Amorphous Alloys by HAADF-STEM
Authors: Tanaka N , Penny cook SJ , Fujiwara T , Fukunaga T , Mizutani U
Published: July 2020

A combination of Si and transition metal element like V, Ni and Au can form an amorphous phase over a wide composition range. Extensive studies have been reported in relation to a change in the electron transport properties across the metal-insulator transition. It has been reported that the metal-insulator transition in the amorphous Si100−xVx alloys accompanies a substantial change in both the electronic structure and atomic structure around x=18, as revealed by the photoemission spectroscopy and neutron diffraction experiments[1]. It is of great interest to examine the structural change associated with the metal-insulator transition at an atomic level by utilizing the HRTEM[2]. However, the correspondence between the image contrast and projection of atomic structures in amorphous materials is usually indirect due to the well-known phenomena of phase contrast in HRTEM. High-angle detection annular dark field scanning transmission electron microscopy (HAADF-STEM) as illustrated in Fig.1 is a solution of the problem without contrast reversal due to the lens-defocus and thickness-variation of samples.
Electron Diffraction Analysis and Determination of Se Phase Formed by Reduction of Oxoselenium Anions by Iron (II) Hydroxide
Authors: Dufner D C , Zingaro R A , Murphy A P , Moody C D
Published: July 2020

Since the early 1980s, Se toxicity in wildlife has created a great deal of interest and concern. Reservoirs, marshes, and wetlands in which excessive amounts of Se have been found are considered to be the source of their toxicity problems. Thus, an effective and inexpensive treatment of Se-contaminated waters which significantly lowers the concentration of this element is needed. One such method for removing selenites and selenates from water utilizes iron (II) hydroxide as a reducing agent. In this work, the reduction products are analyzed in the transmission electron microscope (TEM) using electron diffraction and energy-dispersive spectroscopy (EDS) to determine the presence of Se.

A “standard” aqueous solution was prepared by the addition of KOH to distilled water to pH 8.8. Sufficient quantities of Na2SeO3 or Na2SeO4 were weighed and dissolved in the “standard” solution to yield SeO3  -2 or SeO4  -2 ions. A weighed quantity of Fe(NH4)2(SO4)2 was then added to the SeO3  -2 or SeO4  -2 “standard” solution to form a precipitate of iron hydroxide.
Cross-Section TEM Study On Kr+ Irradiation-Induced Amorphization in Quartz
Authors: Gong WL , Wang LM , Ewing RC
Published: July 2020

Radiation damage in quartz has been of interest to the semiconductor industry, optical fiber industry, and nuclear industry. Cross-section transmission electron microscopy (TEM) is a powerful tool for investigating the irradiation effects since it provides a direct measurement of the ion and the damage distributions, and can also provide detailed microstructural information such as the presence of amorphous regions and the size, density and chemical nature of defect aggregates. The results reported below are from a systematic cross-section TEM study on 1.5 MeV Kr+ ion irradiated quartz.

3-mm discs of quartz (along 010 face) were prepared with 100 μm in thickness. One side for each discs was well polished using a 0.05 μm diamond paste. The well-polished side was irradiated at room temperature with 1.5 MeV Kr ions in the HVEM-Tandem Facility at Argonne National Laboratory. Following irradiation, cross-section TEM specimens were prepared using the so-called T-tool technique, a modified tripot technique
Growth of ZrO2 Corrosion Film on Zr-2.5%Nb Pressure Tube Alloy
Authors: Lin Y P
Published: July 2020

The microstructure of Zr-2.5wt%Nb pressure tubes used in CANDU reactors consists α-Zr grains with a [110] texture in the radial direction and surrounded by a thin layer of metastable β-Zr. Information on oxide formed on β-regions have been reported. For the predominantly monoclinic ZrO2 (a=0.514, b=0.521, c=0.531nm, β=99.2°) formed α-Zr, two types of grain morphology and texture have been observed. In some areas of the oxide, columnar grains with a fibre texture exhibit no specific orientation relationship with the metal; such regions are not the subject here. Results presented here address a textured growth mode which is sensitive to the metal orientation.

Plan-view foils of oxide on the pressure tube radial-normal surface formed by a treatment of 24 hours in steam were prepared by ion-beam thinning and examined in a JEOL 2010 TEM. Selected area diffraction (SAD) and convergent beam diffraction (CBD) patterns showed that oxide growth mode was dominated by a [001] growth and consisted of a combination of orientation related [001] growth and mixed [001]/[100] growth.
A Study of An Yttria-Doped Zirconia Coating With Electron Microprobe Wavelength Dispersive Compositional Mapping
Authors: Marinenko Ryna B , Bright David S , Steel Eric B
Published: July 2020

Yttria-doped zirconia plasma-sprayed thermal barrier coatings (TBC’s) have been used successfully to improve the performance and extend the life of industrial equipment such as jet engines. For this reason, there is considerable interest in understanding and improving the plasma spray process and resulting TBC’s. A collaborative research program exists between Sandia National Laboratories and the National Institute of Science and Technology (NIST) to study the materials and processes used in preparing the coatings as well as the relationship between the physical properties of the coating and its microstructure.

The purpose of this work was to determine the elemental compositions on a micrometer scale of an yttria-doped zirconia coating. The cubic and tetragonal crystal forms of the yttria-doped zirconia have the most favorable thermal expansion coefficient, therefore providing the most effective thermal barrier. The Y concentration in these crystal phases is known to be 6-7 wt%, while the less desirable monoclinic phase, having a less favorable thermal expansion coefficient, contains less that 3 wt% Y.
Soft X-Ray Spectroscopy of Amino Acids and Peptides
Authors: Osanna A , Boese J , Jacobsen C , Kirz J
Published: July 2020

Soft x-rays provide a high signal-to-background ratio and an energy resolution of 0.1 - 0.5 eV for quantitative microanalysis of thin organic specimens. For specimens with non-uniform thickness, it it necessary to take spatially resolved spectra for quantitative analysis. In the Stony Brook scanning transmission x-ray microscope, spectra can be acquired from ∼ 0.2 micron spots, and images at selected energies can be acquired at < 55 nm Rayleigh resolution. This spectromicroscopy capability has been used for biological applications including the mapping of protein and DNA so as to rule out certain models of chromosome packing in sperm, the mapping of calcium in bone and tendon tissue, and for polymer science applications.

We have investigated x-ray absorption near edge structure (XANES) of amino acids and peptides at the carbon K-edge. We find strong evidence that spectra of small proteins can be predicted from amino acid spectra
Multivariate Statistical Analysis of Spectrum Lines From Si3N4 Grain Boundaries
Authors: Rice P M , Alexander K B , Anderson I M
Published: July 2020

It is well known that the high-temperature properties of polycrystalline Si3N4 ceramics are strongly influenced by the nanometer-scale glassy phase at the grain boundaries. We have recently analyzed the variation of the near-edge fine structure (ELNES) of the Si-L2,3 edges using a combination of TEM spectrum-line acquisition with an imaging filter and multivariate statistical analysis.

The glassy phase at the Si3N4 grain boundaries is easily damaged by the the fine probes usually used in scanning transmission electron microscopy to acquire ELNES data. Thus an alternative method using a Gatan imaging filter (GIF), called TEM spectrum-line analysis, was used. In this mode, energy-loss spectra are dispersed along one axis of the CCD detector, while the orthogonal axis displays the spatial variation across the interface. In this mode, a slotted washer is used as the GIF entrance aperture, with its minor axis parallel to the energy-dispersion direction of the spectrometer.