bluuebunny/crossref_metadata_2025 huggingface dataset:
Durability of traditional clamped joints in the vapour barrier layer: experimental and numerical analysis
Authors: Gullbrekken Lars , Gradeci Klodian , Norvik Øyvind , Rüther Petra , Geving Stig
Published: March 2019

Clamped joints of wood frame buildings are a traditional way in Norway to attain airtight joints for the air and vapour barrier. There are numerous defects registered in the SINTEF Building Defects Archive related to air leakage through the vapour barrier, on one hand, and stricter requirements for reduced energy consumption, on the other hand, question today’s efficacy of these type of joints. This study investigates the durability of clamped joints by studying how the airtightness is affected by several drying and wetting cycles. Experimental work is carried out to measure air leakage rates, which in turn, are used to evaluate their impact on the airtightness of two different constructions by numerical estimations. Results show that the air leakage rates are increased significantly due to transient climatic conditions. Clamped joints may no longer provide airtight building envelopes given the stricter requirements for energy consumption and implications of climate change. A more promising and robust alternative is the use of self-adhesive tapes.
Chinese Society 2018: Stabilising Development Amid Uncertainties
Authors: ZHAO Litao
Published: March 2019

China had a bumpy year in 2018. The central government had to make a midyear adjustment with renewed emphasis on stabilising the economy and society prompted largely by the US-China trade war and a slew of domestic factors, such as the grieving middle class increasingly burdened by high living costs and growing household debts. By all signs, the year 2019 will be more difficult and a serious test is forthcoming for the Xi leadership.
Hong Kong’s Economy Treading on Slippery Ground
Authors: ZHANG Yang , TONG Sarah Y
Published: March 2019

Hong Kong’s economy is projected to have grown by 3.2% in 2018, a moderation from a buoyant 3.7% in 2017. This relatively robust performance was sustained by healthy domestic demand and a steady growth in external demand. Economic ties with the Mainland continued to strengthen, with completed and new infrastructure projects. For 2019, however, Hong Kong’s economy faces new challenges, related both to uncertainties in the global economy and possible deterioration in China-US economic relations.
Numerical Study for Soil Response Around Submerged Breakwaters with Bragg Reflection
Authors: Cui L. , Jeng D.-S.
Published: March 2019

A better understanding of soil behavior in a seabed foundation around submerged breakwaters under combined wave and current loadings has become crucial regarding the design and maintenance for such breakwaters. Bragg effect is considered in this study, which is one of the important factors that influence the flow field and soil response in the vicinity of multiple breakwaters. The wave-current induced dynamic soil response (effective stresses, pore pressures and displacements) and its resultant residual liquefaction in a loosely deposited seabed foundation around multiple breakwaters are investigated. In this study, the wave motion is governed by VARANS equation and the Biot’s [Formula: see text]–[Formula: see text] approximation is used to govern soil-fluid interactions in porous medium. The elasto-plastic constitutive model (PZIII) is used to reproduce the plastic soil behavior in seabed foundation under long-term cyclic ocean loading. Numerical results show that the flow motion can be largely changed due to Bragg effects. The construction of breakwaters significantly change the stress field in seabed foundation. Parametric study shows that, under the strongest Bragg effect, the presence of currents, soil properties and wave characteristics have great impact on the liquefaction potential.
Practical Considerations in Providing Preimplantation Genetic Testing for Aneuploidies (PGT-A)
Authors: Yeung Queenie S.Y. , Zhang Ying Xin , Chung Jacqueline P.W. , Kwok Yvonne K.Y. , Gui Baoheng , Choy Kwong Wai , Li Tin Chiu
Published: March 2019

Preimplantation genetic testing for aneuploidies (PGT-A) has been controversial in its application to improve reproductive success, reduce time-to-pregnancy, and serve the intention-to-treat. Nevertheless, many in vitro fertilization (IVF) units have already introduced the service for one reason or another. Given PGT-A is not a stand-alone technique but a clinical service involving several disciplines, this mini review discussed the factors that can influence success rates when PGT-A is applied and highlighted practical issues encountered by clinicians, embryology, and genetics laboratories involved in the provision of PGT-A service.
A Comparison of the Miscarriage and Live Birth Rate for Frozen Embryo Transfer According to Two Endometrial Preparations: Natural or Primed with Estrogens
Authors: Mubarak S. , Acharyya S. , Viardot-Foucault V. , Tan H. H. , Phoon J. W. L.
Published: March 2019

Objective The primary objective is to compare miscarriage rates in frozen-thawed embryo transfer (FET) cycles, according to the endometrial preparation used either artificial through the administration of exogenous estrogen and progesterone or natural without any treatment, during a spontaneous ovulatory cycle. The secondary objective is to compare the live birth rates between the two endometrial preparations.

Study design This is a retrospective study done at KK Women’s and Children’s Hospital Singapore. We included women who underwent FET cycles either with hormone replacement treatment (HRT) or no treatment (natural) for the endometrial preparation, regardless of their cycle number, from 1 January 2011 till 31 December 2015.

Results A total of 2,752 FET cycles were included in our analysis. The natural cycle followed by vaginal progesterone support was used in 1,221 cycles and the HRT cycle with estrogen and vaginal progesterone was used in 1,531 cycles. There is a significantly higher miscarriage rate in the HRT group (38.4%) compared with the natural group (22.3%). The live birth rate is significantly higher in the natural group (22.8%) compared with the HRT group (17.3%). The multivariate analysis further shows that the HRT therapy is independently associated with an increased risk of miscarriage (adjusted odds ratio 2.05; 95% confidence interval 1.45–2.90; [Formula: see text] <0.001) and hence lower odds of live birth (adjusted odds ratio 0.69; 95% confidence interval 0.56–0.84; [Formula: see text] <0.001) after adjusting for the patient’s age at which the embryo was cryopreserved, race, body mass index, main indications for in vitro fertilization, number of embryos transferred and type of embryo transferred.

Conclusion We have shown in this study that the miscarriage rate is higher in the HRT FET group and that this increased miscarriage rate translates into a lower live birth rate in the HRT group. Thus, we conclude that patients with regular menstrual cycles should be offered a natural FET cycle to achieve better outcomes in terms of live birth rate and reducing the miscarriage rate.
Oops
Authors: Samie Farzad , Tsoutsouras Vasileios , Bauer Lars , Xydis Sotirios , Soudris Dimitrios , Henkel Jörg
Published: March 2019

The massive increase of IoT devices and their collected data raises the question of how to analyze all that data. Edge computing provides a suitable compromise, but the question remains: How much processing should be done locally vs. offloaded to other devices? The diverse application requirements and limited resources at the edge extend the challenges.

We propose
Oops
, an optimization framework to adapt the resource management at runtime distributedly. It orchestrates the IoT devices and adapts their operation mode with respect to their constraints and the gateway’s limited shared resources. Oops reduces runtime overhead significantly while increasing user utility compared to state-of-the-art.
Computer-aided Arrhythmia Diagnosis with Bio-signal Processing
Authors: Dinakarrao Sai Manoj Pudukotai , Jantsch Axel , Shafique Muhammad
Published: March 2019

Signals obtained from a patient, i.e., bio-signals, are utilized to analyze the health of patient. One such bio-signal of paramount importance is the electrocardiogram (ECG), which represents the functioning of the heart. Any abnormal behavior in the ECG signal is an indicative measure of a malfunctioning of the heart, termed an
arrhythmia condition
. Due to the involved complexities such as lack of human expertise and high probability to misdiagnose, long-term monitoring based on computer-aided diagnosis (CADiag) is preferred. There exist various CADiag techniques for arrhythmia diagnosis with their own benefits and limitations. In this work, we classify the arrhythmia detection approaches that make use of CADiag based on the utilized technique. A vast number of techniques useful for arrhythmia detection, their performances, the involved complexities, and comparison among different variants of same technique and across different techniques are discussed. The comparison of different techniques in terms of their performance for arrhythmia detection and its suitability for hardware implementation toward body-wearable devices is discussed in this work.
Composable Probabilistic Inference Networks Using MRAM-based Stochastic Neurons
Authors: Zand Ramtin , Camsari Kerem Y. , Datta Supriyo , Demara Ronald F.
Published: March 2019

Magnetoresistive random access memory (MRAM) technologies with thermally unstable nanomagnets are leveraged to develop an intrinsic stochastic neuron as a building block for restricted Boltzmann machines (RBMs) to form deep belief networks (DBNs). The embedded MRAM-based neuron is modeled using precise physics equations. The simulation results exhibit the desired sigmoidal relation between the input voltages and probability of the output state. A probabilistic inference network simulator (PIN-Sim) is developed to realize a circuit-level model of an RBM utilizing resistive crossbar arrays along with differential amplifiers to implement the positive and negative weight values. The PIN-Sim is composed of five main blocks to train a DBN, evaluate its accuracy, and measure its power consumption. The MNIST dataset is leveraged to investigate the energy and accuracy tradeoffs of seven distinct network topologies in SPICE using the 14nm HP-FinFET technology library with the nominal voltage of 0.8V, in which an MRAM-based neuron is used as the activation function. The software and hardware level simulations indicate that a 784× 200× 10 topology can achieve less than 5% error rates with ∼400pJ energy consumption. The error rates can be reduced to 2.5% by using a 784× 500× 500× 500× 10 DBN at the cost of ∼10× higher energy consumption and significant area overhead. Finally, the effects of specific hardware-level parameters on power dissipation and accuracy tradeoffs are identified via the developed PIN-Sim framework.
A Mixed Signal Architecture for Convolutional Neural Networks
Authors: Lou Qiuwen , Pan Chenyun , McGuinness John , Horvath Andras , Naeemi Azad , Niemier Michael , Hu X. Sharon
Published: March 2019

Deep neural network (DNN) accelerators with improved energy and delay are desirable for meeting the requirements of hardware targeted for IoT and edge computing systems. Convolutional neural networks (CoNNs) belong to one of the most popular types of DNN architectures. This article presents the design and evaluation of an accelerator for CoNNs. The system-level architecture is based on mixed-signal, cellular neural networks (CeNNs). Specifically, we present (i) the implementation of different layers, including convolution, ReLU, and pooling, in a CoNN using CeNN, (ii) modified CoNN structures with CeNN-friendly layers to reduce computational overheads typically associated with a CoNN, (iii) a mixed-signal CeNN architecture that performs CoNN computations in the analog and mixed signal domain, and (iv) design space exploration that identifies what CeNN-based algorithm and architectural features fare best compared to existing algorithms and architectures when evaluated over common datasets—MNIST and CIFAR-10. Notably, the proposed approach can lead to 8.7× improvements in energy-delay product (EDP) per digit classification for the MNIST dataset at iso-accuracy when compared with the state-of-the-art DNN engine, while our approach could offer 4.3× improvements in EDP when compared to other network implementations for the CIFAR-10 dataset.
Fast Query Answering over Existential Rules
Authors: Leone Nicola , Manna Marco , Terracina Giorgio , Veltri Pierfrancesco
Published: March 2019

Enhancing Datalog with existential quantification gives rise to Datalog
∃
, a powerful knowledge representation language widely used in ontology-based query answering. In this setting, a conjunctive query is evaluated over a Datalog
∃
program consisting of extensional data paired with so-called “existential” rules. Owing to their high expressiveness, such rules make the evaluation of queries undecidable, even when the latter are atomic. Decidable generalizations of Datalog by existential rules have been proposed in the literature (such as weakly acyclic and weakly guarded); but they pay the price of higher computational complexity, hindering the implementation of effective systems. Conversely, the results in this article demonstrate that it is definitely possible to enable fast yet powerful query answering over existential rules that strictly generalize Datalog by ensuring decidability without any complexity overhead. On the theoretical side, we define the class of parsimonious programs that guarantees decidability of atomic queries. We then strengthen this class to strongly parsimonious programs ensuring decidability also for conjunctive queries. Since parsimony is an undecidable property, we single out Shy, an easily recognizable class of strongly parsimonious programs that generalizes Datalog while preserving its complexity even under conjunctive queries. Shy also generalizes the class of linear existential programs, while it is uncomparable to the other main classes ensuring decidability. On the practical side, we exploit our results to implement DLV
∃
, an effective system for query answering over parsimonious existential rules. To assess its efficiency, we carry out an experimental analysis, evaluating DLV
∃
performances for ontology-based query answering on both real-world and synthetic ontologies.
Cloud, Fog, or Mist in IoT? That Is the Question
Authors: Vasconcelos D. R. , Andrade R. M. C. , Severino V. , Souza J. N. De
Published: March 2019

Internet of Things (IoT) has been commercially explored as Platforms as a Services (PaaS). The standard solution for this kind of service is to combine the Cloud computing infrastructure with IoT software, services, and protocols also known as CoT (Cloud of Things). However, the use of CoT in latency-sensitive applications has been shown to be unfeasible due to the inherent latency of cloud computing services. One proposal to solve this problem is the use of the computational resources available at the edge of the network, which is called Fog computing. Fog computing solves the problem of latency but adds complexity to the use of these resources due to the dynamism and heterogeneity of the IoT. An even more accentuated form of fog computing is Mist computing, where the use of the computational resources is limited to the close neighborhood of the client device. The decision of what computing infrastructure (Fog, Mist, or Cloud computing) is the best to provide computational resources is not always simple, especially in cases where latency requirements should be met by CoT. This work proposes an algorithm for selecting the best physical infrastructure to use the computational resource (Fog, Mist, or Cloud computing) based on cost, bandwidth, and latency criteria defined by the client device, resource availability, and topology of the network. The article also introduces the concept of feasible Fog that limits the growth of device search time in the neighborhood of the client device. Simulation results suggest the algorithm’s choice adequately attends the client’s device requirements and that the proposed method can be used in IoT environment located on the edge of the network.
TCF21 inhibits tumor-associated angiogenesis and suppresses the growth of cholangiocarcinoma by targeting PI3K/Akt and ERK signaling
Authors: Duan Hua-Xin , Li Bo-Wen , Zhuang Xin , Wang Lu-Ting , Cao Qian , Tan Ling-Hua , Qu Gui-Fang , Xiao Shuang
Published: March 2019

Tumor-associated angiogenesis plays a critical role in the pathogenesis of cholangiocarcinoma (CCA). In this study, we examined the biological effects and molecular mechanisms of transcription factor 21 (TCF21) on CCA-associated angiogenesis. TCF21 expression was compared between 15 pairs of peritumor normal tissues and CCA tissues and also between normal bile duct epithelial cells and two CCA cell lines (QBC-939 and TFK-1) using real-time PCR and Western blot. With the use of both CCA cell lines as the model system, we stably expressed TCF21 by lentiviral transduction (Lv-TCF21). In vivo, we monitored xenograft growth from different CCA cells, measured tumor-associated angiogenesis by histological analysis, and determined the expressions and circulatory levels of VEGFA and PDGF-BB by immunohistochemistry and ELISA, respectively. In vitro, we assessed the effects of conditioned medium collected from different CCA cells on the viability, migration, and tube formation of endothelial cells and explored the significance of phosphatidylinositol 3-kinase/protein kinase B (PI3K/Akt), as well as ERK1/2 signaling in this process. TCF21 was significantly downregulated in CCA tissues or cell lines. Ectopic expression of TCF21 in CCA cells inhibited xenograft growth or tumor-associated angiogenesis in vivo and targeted the expression and secretion of proangiogenic factors, VEGFA and PDGF-BB. In vitro, the conditioned medium collected from Lv-TCF21 CCA cells significantly reduced the viability, migration, and tube formation of endothelial cells. On the molecular level, the targeting of PI3K/Akt and ERK1/2 signaling mediated the anti-angiogenic activity of TCF21. TCF21 presents growth-inhibitory and anti-angiogenic activities, and thus the elevation of TCF21 expression may provide therapeutic benefits for CCA.

NEW & NOTEWORTHY Transcription factor 21 (TCF21) is downregulated in cholangiocarcinoma (CCA) tissues or cells. TCF21 inhibits the growth of xenografts derived from CCA cells. TCF21 suppresses in vivo tumor-associated angiogenesis. TCF21 targets expression and production of proangiogenic factors from CCA cells. The targeting of phosphatidylinositol 3-kinase/protein kinase B and ERK1/2 signaling mediates the anti-angiogenesis of TCF21.
Translational and transcriptional responses in human primary hepatocytes under hypoxia
Authors: Hettiarachchi Gaya K. , Katneni Upendra K. , Hunt Ryan C. , Kames Jacob M. , Athey John C. , Bar Haim , Sauna Zuben E. , McGill Joseph R. , Ibla Juan C. , Kimchi-Sarfaty Chava
Published: March 2019

The liver is the primary source of a large number of plasma proteins and plays a critical role in multiple biological processes. Inadequate oxygen supply characterizing various clinical settings such as liver transplantation exposes the liver to hypoxic conditions. Studies assessing hypoxia-induced global translational changes in liver are lacking. Here, we employed a recently developed ribosome-profiling technique to assess global translational responses of human primary hepatocytes exposed to acute hypoxic stress (1% O2) for the short term. In parallel, transcriptome profiling was performed to assess mRNA expression changes. We found that translational responses appeared earlier and were predominant over transcriptional responses. A significant decrease in translational efficiency of several ribosome genes indicated translational inhibition of new ribosome protein synthesis in hypoxia. Pathway enrichment analysis highlighted altered translational regulation of MAPK signaling, drug metabolism, oxidative phosphorylation, and nonalcoholic fatty liver disease pathways. Gene Ontology enrichment analysis revealed terms related to translation, metabolism, angiogenesis, apoptosis, and response to stress. Transcriptional induction of genes encoding heat shock proteins was observed within 30 min of hypoxia. Induction of genes encoding stress response mediators, metabolism regulators, and proangiogenic proteins was observed at 240 min. Despite the liver being the primary source of coagulation proteins and the implicated role of hypoxia in thrombosis, limited differences were observed in genes encoding coagulation-associated proteins. Overall, our study demonstrates the predominance of translational regulation over transcription and highlights differentially regulated pathways or biological processes in short-term hypoxic stress responses of human primary hepatocytes.

NEW & NOTEWORTHY The novelty of this study lies in applying parallel ribosome- and transcriptome-profiling analyses to human primary hepatocytes in hypoxia. To our knowledge, this is the first study to assess global translational responses using ribosome profiling in hypoxic hepatocytes. Our results demonstrate the predominance of translational responses over transcriptional responses in early hepatic hypoxic stress responses. Furthermore, our study reveals multiple pathways and specific genes showing altered regulation in hypoxic hepatocytes.
Intrapancreatic fat deposition and visceral fat volume are associated with the presence of diabetes after acute pancreatitis
Authors: Singh Ruma G. , Cervantes Aya , Kim Jin Uk , Nguyen Ngoc Nhu , DeSouza Steve V. , Dokpuang Dech , Lu Jun , Petrov Maxim S.
Published: March 2019

Ectopic fat and abdominal adiposity phenotypes have never been studied holistically in individuals after acute pancreatitis (AP). The aim of the study was to investigate phenotypical differences in ectopic fat and abdominal fat between individuals after AP (with and without diabetes) and to determine the role of pancreatitis-related factors. Eighty-four individuals were studied cross-sectionally after a median of 21.5 mo since last episode of AP and were categorized into “diabetes” and “no diabetes” groups. Twenty-eight healthy volunteers were also recruited. With the use of magnetic resonance imaging, intrapancreatic fat percentage, liver fat percentage, visceral fat volume (VFV), subcutaneous fat volume, and visceral-to-subcutaneous (V/S) fat volume ratio were quantified. Analysis of variance was used to investigate the differences in these phenotypes between the groups. All analyses were adjusted for age and sex. Linear regression analysis was used to investigate the association between pancreatitis-related factors and the studied phenotypes. Intrapancreatic fat percentage was significantly higher in the diabetes group (10.2 ± 1.2%) compared with the no diabetes (9.2 ± 1.7%) and healthy volunteers (7.9 ± 1.9%) groups ( P < 0.001). VFV was significantly higher in the diabetes (2,715.3 ±1,077.6 cm3) compared with no diabetes (1,983.2 ± 1,092.4 cm3) and healthy volunteer (1,126.2 ± 740.4 cm3) groups ( P < 0.001). V/S fat volume ratio was significantly higher in the diabetes (0.97 ± 0.27) compared with no diabetes (0.68 ± 0.42) and healthy volunteer (0.52 ± 0.34) groups ( P = 0.001). Biliary AP was associated with significantly higher intrapancreatic fat percentage (β = 0.67; 95% CI, 0.01, 1.33; P = 0.047). C-reactive protein levels during hospitalization for AP were associated with significantly higher VFV (β = 3.32; 95% CI, 1.68, 4.96; P < 0.001). In conclusion, individuals with diabetes after AP have higher intrapancreatic fat percentage, VFV, and V/S fat volume ratio. Levels of C-reactive protein during AP are significantly associated with VFV, whereas biliary AP is significantly associated with intrapancreatic fat percentage.

NEW & NOTEWORTHY Individuals with diabetes after acute pancreatitis have significantly higher intrapancreatic fat percentage and visceral fat volume compared with individuals without diabetes after acute pancreatitis and healthy controls. C-reactive protein levels during hospitalization for acute pancreatitis and biliary etiology of acute pancreatitis are associated with significantly larger visceral fat and pancreatic fat depots, respectively.
A Simplified Procedure for Calculating Peak Position in X-ray Residual Stress Measurements on Hardened Steel
Authors: Koistinen D. P. , Marburger R. E. , Mitchell R. P.
Published: March 2019

In the measurement of residual stresses in hardened carbon steels by X-ray diffraction the principal difficulty encountered is determining the precise location of the broad diffraction lines. Christenson and RowlandM have proposed a workable technique, but it entails a complicated correction calculation. A simplified correction procedure, based on theoretical considerations, will be described which shortens the time required to obtain accurate data and cuts the time required for calculation to a fraction of that required for the previous method.

It can be shown that the asymmetry of the broad diffraction lines in the back reflection region is largely due to 6 dependent intensity factors. Thus, the proposed correction procedure uses a multiplicative correction to peak intensity which includes all significant geometrical and absorption factors. The line position is then determined accurately as the axis of a parabola fitted to the corrected data. Since the data is taken in the vicinity of the peak, the time required to obtain accurate data is reduced and furthermore it is possible to determine residual stresses in as-quenched steel even though the structure is tetragonal.

Examples of the type of stresses measured and the correlation between this new method and that of Christenson and Rowland will be presented.
Electrolytic Isolation and the X-Ray Study of Micro-constituents in Steels
Authors: Andrews Kenneth W. , Hughes Hugh
Published: March 2019

The identification of phases in solid steel specimens is subject to well known limitations. With suitable techniques, however, phases present in exceedingly small amounts can be isolated and identified. The work to be described is represented by three main stages.

1.

The techniques of isolation. The aim has been simplicity with the maximum efficiency of separation. Simple open and closed type cells are used and a few selected electrolytes for different conditions.

2.

The second stage is the identification of the separated particles. The X-ray photographs do, however, provide a considerable amount of other data which are often as important as the identity of the constituents. Thus, information can be obtained about the shape and size of particles and lattice spacing changes in solid solution phases. A supplementary determination of the solid solution content of the matrix is often useful.

3.

The third stage involves the interpretation of the results in relation to the strength and other properties of the steel or alloy. Here such questions arise as the effects of particular carbides or intermetallic phases, solid solution hardening and the times involved in various reactions and their relation to creep, etc.

A number of examples are given and some limitations noted.
X-Ray Spectrographic Determination of Tantalum, Columbium, Iron, and Titanium Oxide Mixtures Using Simple Arithmetic Corrections for Inter element Effects
Authors: Mitchell Betty J.
Published: March 2019

A method of specific arithmetic corrections for absorption and enhancement interelement effects has been developed, with particular reference to the quantitative determination of mixtures of tantalum, columbium, iron, and titanium oxides. The combined oxides of these elements are prepared chemically from liquid, powder, or metallic samples; weight percantages are determined by reference to calibration and intensity correction curves relating fluorescent intensity to concentration and sample matrix. Tantalum, columbium, iron, or titanium oxide from 0.01 to 100% concentration can be determined with a reproducibility of 1% of the amount present at the 50% concentration and 10% of the amount present at the 1 or 0, 1% level. X-ray analytical time required averages less than 10 minutes per determination. The corrections which have been established are universally applicable to combinations of these four oxides which may be obtained by chemical treatment from such materials as columbite or tantalite ores, tantalum or columbium metalSj and titanium alloys. The method of arithmetic corrections for interelement effects is general in nature and may be applied to the determination of other elements in complex matrices.
Rock Analysis by X-Ray Fluorescence Spectroscopy
Authors: Chodos Arthur A.
Published: March 2019

Our laboratory has been interested in the use of the X-ray spectragraph for routine rock analysis within limited rock types. This paper is meant as a progress report and to indicate the direction of our work on amphibolites to others interested ill the problem of rock analysis.

Even with the use of flow counters and pulse discriminators the intensities of the magnesium, aluminum and silicon peaks are quite low and most dilution techniques may not be used. The direct determination of major elements (except sodium) yields results directly comparable to the chemical results for potassium; manganese and titanium in the range from 0: 1 to 3% as the oxides. For iron (10-20%), calcium (8-12%) and silicon (45-52%) the accuracy is 2-3% but for each element occasional samples will be 5% from the chemical values. Aluminum and magnesium yield erratic results.

The use of ratios between elements occurring in. the samples yields slightly improved accuracies. The use of a strong absorber such as tungstic acid (40% by weight) greatly improves the ratios for aluminum and magnesium., without appreciably affecting their intensities. By a combination of the direct and tungstic acid techniques it is possible to attain accuracies of 2-3% with analysis time of two hours. At present we are attempting a combination with an internal standard method to yield greater accuracy.
Micro-Analysis by X-Ray Absorption, Fluorescence, Emission and Diffraction Using Ultra-Fine X-Ray Sources
Authors: Cosslett V. E. , Duncumb P. , Long J. V. P. , Nixon W. G.
Published: March 2019

Fine focus X-ray tubes developed for projection X-ray microscopy can also be used for X-ray micro-analysis. Areas about 10 microns in diameter of thin sections have been analyzed by measuring differences in X-ray transmission, with particular reference to the determination of calcium in biological materials and in minerals. The high intensity of this X-ray point source has permitted micro-fluorescence analysis of similar small areas with high sensitivity and reasonable time. The same electron optical system has been used for micro-emission analysis of rock slices and mineral grains. By scanning the electron beam over the specimen surface and recording either the scattered electrons or the emitted X-rays, a two-dimensional picture can be displayed of the physical features or of the distribution of a particular element respectively. The analysis of a selected, volume of 1 cubic micron in the surface has been obtained by plotting the characteristic line emission spectrum with a crystal spectrometer and proportional counter. The sensitivity is 0. 1% or 10−1 gram. Micro-beam X-ray diffraction has also been used with a stationary X-ray source both for transmission and back reflection with a 10 minute exposure from a 10 micron diameter area.
Feasibility of the X-Ray Spectrograph as a Continuous Analytical Instrument for Process Control
Authors: McCune Robert A. , Mueller William M. , Dunton Pauline J.
Published: March 2019

Studies have been made of the application of X-ray spectrography to continuous analysis for process control. To date the most widespread application of fluorescent X-ray spectrography to process control has been in measurement of plating thickness. Realizing that many other processes could use a method of continuous analysis of moving materials, these studies were undertaken.

A modified tube housing and sample holder was constructed so that material could be passed through the X-ray beam, of a conventional X-ray spectrograph at various linear speeds. Detectability versus material speeds were studied for a number of elements in various mediums.

Application of fluorescent X-ray spectrography as a continuous analytical tool looks very promising. Further studies on specific plant problems should provide useful and advantageous industrial applications of the basic information developed here.
On the Mechanism of Recrystallization of Aluminum
Authors: Weissmann Sigmund
Published: March 2019

Recrystallization and grain growth of 99.998% aluminum were studied by methods combining metallographic techniques with x-ray microscopy and diffraction analysis. The recrystallked grains were shown to be the product of preferential subgrain growth whereby subgrains subtending large disoriciitation angles with respect to their neighbors exhibited the highest velocity of growth. The recrystallized grains emerging from the deformed matriv showed at first a high degree of lattice perfection, but incurred growth accidents during the growth process. Values for the mean strain-free energy of the deformed matrix surrounding the growing subgrains were obtained from the kinetics of subgrain growth.
Selection of Spectra for X-Ray Microscopy
Authors: Bessen I. I.
Published: March 2019

By selecting particular spectra the contrast of images may be closely controlled. Furthermore, absorption analysis of regions as small as 10 microns may be performed. Application of the absorption technique on mineral sections and the instrumental requirements for the technique are discussed.
Techniques for X-Ray Diffraction Studies of Radioactive Materials
Authors: Cummings W. V. , Gruber W. J.
Published: March 2019

Many materials, both fissionable and non-fissionable, become very radioactive when subjected to nuclear radiations. This radioactivity results in a high background level in X-ray diffraction studies and becomes a limiting factor in an analysis of radiation damage. A description is given of special techniques that are used to minimize this background and produce optimum diffraction conditions. The radioactive intensity of irradiated X-ray specimens varies from levels that are only mildly troublesome to levels that are extremely hazardous to personnel. The diffraction methods employed at the various levels are explained. An example of the radioactive energy spectrum of a specimen is given to show the method of selecting the best operating conditions and techniques.
A Universal Detector for the X-Ray Spectrograph
Authors: Kiley William R.
Published: March 2019

A detector arrangement has been developed which will give nearly 100% efficiency over the entire range of wavelengths normally used in X-ray spectroscopy, including radiation from Mg Kα. A description of this counter is given and data obtained on pulse height distribution and pulse amplitudes will be discussed. Results obtained with typical specimens will be shown.
Recent Developments in Fluorescent X-Ray Spectrographic-Absorptiometric Analyses of Mineral Systems
Authors: Salmon Merlyn L.
Published: March 2019

Fluorescent x-ray speorographic studies of mineral systems were begun in the Metallurgy Division of the Denver Research Institute in 1953. These studies were concerned with several techniques but the primary research emphasis was placed on a method involving conjunctive analyses by monochromatic x-ray absorptiometry and fluorescent x-ray spectrography.

Experimental data for mineral systems with wide variations in matrix compositions exhibit departures from simple calibration curves relating intensity and concentration for an element in a series of samples analyzed by simple fluorescent x-ray spectrographic procedures.

Absorptiometric measurements are made with a thin layer of the mineral sample as an absorption filter for the monochromatic x-rays emitted by the element in question. The results of these measurements provide information for improvement of the simple correlation of intensity and concentration by manipulation of the experimental data with various operations based on Beer's law of radiation absorption.

The results of work at the Denver Research Institute indicated the feasibility of the fluorescent x-ray spectrographic-absorptiometric method and the current work is an extension of the study of basic fundamentals, mechanical factors and practical applications of the technique.
A Versatile 19-cm-Diameter Low-Temperature Debye-Scherrer Camera
Authors: Taylor A.
Published: March 2019

The camera was constructed to fill the need for a low-temperature instrument capable of yielding high spectral resolution and accurate lattice parameters. Specimen temperatures in the range -190 to 300°C are attainable.

A special feature of the camera is the film holder which is split along the beam axis into two symmetrical halves and which can easily be removed from the base without disturbing the cooling system or the specimen. The specimenholderis mounted on a cross-slide to enable specimens of large radius to be rotated off-center with the beam at glancing incidence to their surface. Finally, diffraction patterns from large metallurgical samples may be obtained by removing one of the film holders and employing the apparatus as a “half camera.”

Some applications of the camera to the thermal expansion of SiC and MnSe are described.
Intensities of the K, L, and M Spectral Lines for the Elements with Atomic Numbers 16 TO 92*
Authors: Campbell William J.
Published: March 2019

Line intensity and background measurements were made on the K lines for the elements with atomic numbers 16 to 60, L lines for the elements above atomic number 42, and M lines for elements above atomic number 80. Three general classes of samples were investigated: (1) infinitely thick, (2) microgram deposits, and (3) thin layers.

These studies show that longer-wavelength L radiation may be preferable to the K series lines from the same element in the range of elements with atomic numbers 42 to 60, In particular the Lα lines are more intense than the K series lines from Class 2 and 3 samples. With Class 1 samples the Lα lines are weaker than the K series but their line-to-background ratio is superior to the K series.

M series lines show little promise for spectrochemical analysis except for elements with atomic numbers 90 to 92; for example, with uranium samples in Class 2 and 3, the very high line-to-background ratio of the UMβ1 line may have limited application.

Elements with atomic numbers from 16 to 22 are more sensitive than expected due to the very high line-to-background ratios and the reduced collimation requirements in this longwavelength region.
Some Irradiation Effects in Nonmetallic Crystals
Authors: Wittels M.C. , Sherrill F.A.
Published: March 2019

Nonmetallic crystals with a variety of structures and chemical compositions have been exposed to fission spectrum neutrons in a core position of the Low Intensity Test Reactor (LITR), Oak Ridge, and examined by X-ray diffraction techniques. Wherever possible, single crystals were employed, and the neutron dosages ranged between 1019 and 1021 neutrons/cm2 at a temperature of approximately 85°C. In no case was a special technique used for examining radioactive materials because the problem of heavy induced radioactivity was greatly reduced by working withcrystals weighing a milligram or less. Both film and counter measurements were employed.
Influence of Goniometric Arrangement and Absorption in Qualitative and Quantitative Analysis of Powders by X-Ray Diffractometry
Authors: Leroux J. , Mahmud M.
Published: March 2019

A theoretical approach of some factors influencing the intensity diffracted by a polycrystalline material at a definite Bragg angle has been confirmed by experimental data obtained with a high-angle Norelco diffractometer. The factors mainly considered are the focusing arrangement of the goniometer which delineates the geometric shape of the volume fraction of the sample being irradiated and the absorption of the latter.

Tests have been performed (a) with quartz mixed in samples covering a large range of absorption coefficients, (b) with two different K radiations using copper and molybdenum targets, (c) with three different angles of beam divergence of 1, ½, and ¼°, respectively, and (d) with the sample packed and leveled in a copper grid with openings of about 350 μ. As this test with copper grids was to demonstrate that each opening was acting like a volume of sample irradiated by a beam of extremely small divergence (0.1°), it also shows that more accuracy in the measurement of the exact Bragg angle can be reached in these conditions as compared to that obtained with conventional sample holders.

A general equation, suitable for qualitative and quantitative analysis when these factors have to be taken into consideration, is proposed.
The Application of X-Ray Diffraction to Medical Problems
Authors: Parsons Jonathan
Published: March 2019

The use of the X-ray diffraction Debye-Scherrer powder technique for the identification of crystalline material often found in pathologic tissue is discussed. Cases cited include: heart calcification, lung silicosis, thorium dioxide in liver and spleen, and granulomas of the skin and pericardium. The routine analysis of kidney stones using powder cameras as well as an X-ray diffractometer will be described.
The Use of Optical Transforms in Crystal-Structure Analysis
Authors: Hargreaves Arnold
Published: March 2019

Optical transforms are of particular value In the earlier stages of crystal-structure determination; they enable trial structures to be tested rapidly and may indicate the nature of changes which will improve a postulated structure. The optical transforms are produced in a simple instrument called an optical diffractometer. The projected positions of the atoms in a postulated structure are represented by a set of holes punched in a mask, and the diffractometer produces the Fraunhofer diffraction pattern of the mask. The distribution of intensity in the optical transform is comparable, when sampled at suitable Intervals, with the distribution of intensity among the observed intensities in a particular zone of X-ray reflections. The use of optical transforms in the determination of crystal structures and in the study of imperfect structures will be illustrated by examples.
Use of X-Ray Spectrometer Data in Radial Distribution Analysis of the Diffraction Patterns for Amorphous Materials
Authors: Robson H. E. , Broussard L.
Published: March 2019

Previous radial distribution work which we have found reported in the literature has invariably been based on film technique. Our work is entirely based on X-ray spectrometer intensity measurements, Radial distribution (RD) patterns for silica gel and η-aluinina are presented and the correlation with accepted structures for these materials demonstrated. The advantages of spectrometer over film technique are discussed. The entire calculation problem has been programed for the IBM 650 computer, A difference technique which appears very sensitive to small structure changes is described and demonstrated for silica-alumina cracking catalysts. A procedure for identifying systematic errors in the RD pattern is presented.
A New High-Power Microfocus X-Ray Diffraction Unit
Authors: Whitcomb Peter B.
Published: March 2019

The Hilger & Watts microfocus X-ray diffraction instrument has been redesigned to provide a tube allowing up to three times the target loading of previous tubes. The line focus, 6 mm × 100 μ, increases the target loading to 50 kv dc, 10 ma. To accomplish this, a new high-power transformer is provided with a special demountable tube and anode assembly with suitable cooling provided. The original 40 μ and 100 μ tubes are interchangeable with the new tube. Considerable gains in performance with photographic methods are indicated, but more notable is the increase in resolution when the microfocus unit is used as a source of X-ray for a diffractometer. The diffractometer can now be operated under the same conditions as those required for a conventional tube but with the much higher resolution.
Counter Adaptor and Furnace for Weissenberg Camera*
Authors: Young R. A.
Published: March 2019

A rugged and versatile counter adaptor for a Weissenberg camera is described. It has performed well in two years of daily use which has included collection of intensity vs. temperature data with conventional cold-stream techniques.

Advantage has recently been taken of the adaptor design to mount, directly on the Weissenberg base, a furnace device which blows hot air along the crystal mounting axis. Crystal temperature may be held constant or easily varied over the range up to about 700°C, with no obstruction of the X-ray beams and no readjustment of the furnace position, while the entire zero layer and close-in upper layers are explored.
Measurement in the 10 to 100 Angstrom X-Ray Region*
Authors: Henke Burton L.
Published: March 2019

The results of recent work of the Millikan Laboratory of Physics on the physics and application of ultra s oft X-radiation s are summarized. These investigations include (1) the compilation of ultrasoft X-ray interaction coefficients. (2) the development of high-intensity, low-voltage X-ray tubes (100 to 1000 v), (3) the application of pulse-height analysis in flow proportional counter measurement of 10 to 100 A radiations, (4) a detailed study of the photographic action of the ultrasoft X-radiations, and (5) the application of these long wave length X-radiations to micromass and microchemical analysis by mïcroradiographïand total-reflection techniques.
The Spectra of Some Beta-Excited X-Ray Sources with the Multichannel Analyzer
Authors: Preuss Luther E. , Horn Helen , Keiser Thomas W.
Published: March 2019

Three beta-excited X-ray source types (the compound, apposition, and mixture source) have been designed, and the photon spectra compared. Each source in a series was assembled using a single target element with the concentration of pure beta emitter held constant for the series. The apposition source was studied with varying target thicknesses. The compound sources were crystalline precipitates of molybdate and tungstate groups compounded with the nonearrier-free beta emitter. The mixture source consisted of a fine-milled target powder with the beta emitter adsorbed on it. Assay of the X-ray source emission has been done on the Radiation Instrument Development Laboratories (RIDL) lOQ-channel analyzer with a 3-in. Nal detector. Variation in the spectra exists between the source types of a series. Anomalous peaking occurs with the Sr90 MoO4 source emission at 29 key. The compound source, potentially productive, demonstrates poor characteristic spectra.
The Fundamentals of Quantitative Electron-Probe Microanalysis
Authors: Castaing R.
Published: March 2019

Emission-concentration proportionality Is one of the main features of electronprobe mlcroanalysis. It can be interpreted by taking simultaneously Into account the Z/A factor of Webster's law of deceleration and the variation with atomic number of the backscattering ratio. The baclcscattering ratio itself can be deduced approximately from experimental distribution curves of thecharacteristicemisslonjejqpertments on copper-gold alloys show good agreement with the theoretical predictions. An important practical consequence is that regulation of the electron beam falling onto the specimen leads to better results than regulation of the current passing through it. The different corrections are discussed, with special reference to the fluorescence induced by the general continuous spectrum. The case of insulating materials is considered separately; preliminary experiments seem to show that their behavior is not essentially different from that of conducting materials.