bluuebunny/crossref_metadata_2025_split huggingface dataset:
The z‐sbDBA, a new concept for a dynamic sheet‐based fluence field modulator in x‐ray CT
Authors: Huck Sascha Manuel , Fung George S. K. , Parodi Katia , Stierstorfer Karl 
Published: August 2020

PurposeWe present a new concept for dynamic fluence field modulation (FFM) in x‐ray computed tomography (CT). The so‐called z‐aligned sheet‐based dynamic beam attenuator (z‐sbDBA) is developed to dynamically compensate variations in patient attenuation across the fan beam and the projection angle. The goal is to enhance image quality and to reduce patient radiation dose.MethodsThe z‐sbDBA consists of an array of attenuation sheets aligned along the direction. In neutral position, the array is focused toward the focal spot. Tilting the z‐sbDBA defocuses the sheets, thus reducing the transmission for larger fan beam angles. The structure of the z‐sbDBA significantly differs from the previous sheet‐based dynamic beam attenuator (sbDBA) in two features: (a) The sheets of the z‐sbDBA are aligned parallel to the detector rows, and (b) the height of the sheets increases from the center toward larger fan beam angles. We built a motor actuated prototype of the z‐sbDBA integrated into a clinical CT scanner. In experiments, we investigated its feasibility for FFM. We compared the z‐sbDBA to common CT bowtie filters in terms of the spectral dependency of the transmission and possible image variance distribution in reconstructed phantom images. Additionally, the potential radiation dose saving using z‐sbDBA for region‐of‐interest (ROI) imaging was studied.ResultsOur experimental results confirm that the z‐sbDBA can realize variable transmission profiles of the radiation fluence by only small tilts. Compared to the sbDBA, the z‐sbDBA can mitigate some practical and mechanical issues. In comparison to bowtie filters, the spectral dependency is considerably reduced when using the z‐sbDBA. Likewise, more homogeneous image variance distributions can be attained in reconstructed phantom images. The z‐sbDBA allows controlling the spatial image variance distribution which makes it suitable for ROI imaging. Our comparison on ROI imaging reveals skin dose reductions of up to 35% at equal ROI image quality by using the z‐sbDBA.ConclusionOur new concept for FFM in x‐ray CT, the z‐sbDBA, was experimentally validated on a clinical CT scanner. It facilitates dynamic FFM by realizing variable transmission profiles across the fan beam angle on a projection‐wise basis. This key feature allows for substantial improvements in image quality, a reduction in patient radiation dose, and additionally provides a technical solution for ROI imaging.
Couch and multileaf collimator tracking: A clinical feasibility study for pancreas and liver treatment
Authors: Zhang Lei , LoSasso Thomas , Zhang Pengpeng , Hunt Margie , Mageras Gig , Tang Grace 
Published: August 2020

PurposeReal‐time tumor tracking through active correction by the multileaf collimator or treatment couch offers a promising strategy to mitigate delivery uncertainty due to intrafractional tumor motion. This study evaluated the performance of MLC and couch tracking using the prototype iTools Tracking system in TrueBeam Developer Mode and the application for abdominal cancer treatments.MethodsExperiments were carried out using a phantom with embedded Calypso transponders and a motion simulation platform. Geometric evaluations were performed using a circular conformal field with sinusoidal traces and pancreatic tumor motion traces. Geometric tracking accuracy was retrospectively calculated by comparing the compensational MLC or couch motion extracted from machine log files to the target motion reconstructed from real‐time MV and kV images. Dosimetric tracking accuracy was measured with radiochromic films using clinical abdominal VMAT plans and pancreatic tumor traces.ResultsGeometrically, the root‐mean‐square errors for MLC tracking were 0.5 and 1.8 mm parallel and perpendicular to leaf travel direction, respectively. Couch tracking, in contrast, showed an average of 0.8 mm or less geometric error in all directions. Dosimetrically, both MLC and couch tracking reduced motion‐induced local dose errors compared to no tracking. Evaluated with five pancreatic tumor motion traces, the average 2%/2 mm global gamma pass rate of eight clinical abdominal VMAT plans was 67.4% (range: 26.4%–92.7%) without tracking, which was improved to 86.0% (range: 67.9%–95.6%) with MLC tracking, and 98.1% (range: 94.9%–100.0%) with couch tracking. In 16 out of 40 deliveries with different plans and motion traces, MLC tracking did not achieve clinically acceptable dosimetric accuracy with 3%/3mm gamma pass rate below 95%.ConclusionsThis study demonstrated the capability of MLC and couch tracking to reduce motion‐induced dose errors in abdominal cases using a prototype tracking system. Clinically significant dose errors were observed with MLC tracking for certain plans which could be attributed to the inferior MLC tracking accuracy in the direction perpendicular to leaf travel, as well as the interplay between motion tracking and plan delivery for highly modulated plans. Couch tracking outperformed MLC tracking with consistently high dosimetric accuracy in all plans evaluated, indicating its clinical potential in the treatment of abdominal cancers.
On the utility of nonuniformly sampled two‐dimensional NMR spectra in the pharmaceutical industry
Authors: Szigetvári Áron , Szántay Csaba 
Published: August 2020

AbstractIn this work, we discuss representative examples of the application of nonuniform sampling (NUS) in small‐molecule structure determination in a pharmaceutical research and development and quality control setting. We demonstrate the advantages of NUS over traditional sampling in various industrial applications of nuclear magnetic resonance (NMR). We propose an optimal trade‐off between the quality and the time efficiency of ‘routine’ measurements, as demonstrated via a test sample of vinpocetine analyzed on a ‘work horse’ NMR spectrometer. In addition, we present case studies where the application of NUS contributed significantly to the successful completion of some challenging structure determination task at hand. To that end, in some cases, we combined NUS with a method of decoupling in the indirect dimension that gives ‘constant time’ nuclear Overhauser effect spectroscopy (NOESY) and ‘constant time’ heteronuclear multiple bond correlation (HMBC) spectra. NUS proved to be superior over traditional sampling even for the analysis of trace impurities, where the need to cope with a thousand‐fold or even larger dynamic range and low signal‐to‐noise ratio for the impurity signals is quite a challenge.
Subtractive NCE‐MRA: Improved background suppression using robust regression‐based weighted subtraction
Authors: Li Hao , Wang Shuo , Graves Martin J. , Lomas David J. , Priest Andrew N. 
Published: August 2020

PurposeTo correct the intensity difference of static background signal between bright blood images and dark blood images in subtractive non‐contrast–enhanced MR angiography using robust regression, thereby improving static background signal suppression on subtracted angiograms.MethodsRobust regression (RR), using iteratively reweighted least squares, is used to calculate the regression coefficient of background tissues from a scatter plot showing the voxel intensity of bright blood images versus dark blood images. The weighting function is based on either the Euclidean distance from the estimated regression line or the deviation angle. Results from RR using the deviation angle (RRDA), conventional RR using the Euclidean distance, and ordinary leastsquares regression were compared with reference values determined manually by two observers. Performance was evaluated over studies using different sequences, including 36 thoracic flow‐sensitive dephasing data sets, 13 iliac flow‐sensitive dephasing data sets, and 26 femoral fresh blood imaging data sets.ResultsRR deviation angle achieved robust and accurate performance in all types of images, with small bias, small mean absolute error, and high‐correlation coefficients with reference values. Background tissues, such as muscle, veins, and bladder, were suppressed while the vascular signal was preserved. Euclidean distance gave good performance for thoracic and iliac flow‐sensitive dephasing, but could not suppress background tissues in femoral fresh blood imaging. Ordinary least squares regression was sensitive to outliers and overestimated regression coefficients in thoracic flow‐sensitive dephasing.ConclusionWeighted subtraction using RR was able to acquire the regression coefficients of background signal and improve background suppression of subtractive non‐contrast–enhanced MR angiography techniques. RR deviation angle has the most robust and accurate overall performance among three regression methods.
An analytical approach for cased borehole stress calculation in general anisotropic formations
Authors: Wang Hongwei , Fang Xinding , Zhang Shuangxi , Miao Miao 
Published: August 2020

SummaryWe present an explicit analytical approach for calculating the distribution of stress around a circular cased borehole in a general anisotropic formation. This approach is developed based on a pure elastic cased borehole model, which can include multiple cemented concentric casing strings that are surrounded by a homogeneous anisotropic medium. The wall of the innermost casing is under the compression of borehole internal fluid pressure, and the formation can be subjected to arbitrary far‐field stresses. Every casing–cement boundary is assumed to be welded, so as the cement–formation boundary. The derived analytical solution can be applied to an arbitrary wellbore trajectory in an arbitrary anisotropic formation and is also applicable to degenerate isotropic formations. Accuracy and robustness of the analytical solution is validated through comparing its results with those calculated from the classical Kirsch solution for an isotropic example that has identical elastic properties for all materials and from a finite element method for an anisotropic cased borehole example.
A live imaging‐friendly slice culture method using collagen membranes
Authors: Ogaki Ari , Araki Tasuku , Ishikawa Masaya , Ikegaya Yuji , Koyama Ryuta 
Published: August 2020

AbstractAimOrganotypic brain slice culture preserves the geographical position of neurons and neuronal circuits. The slice cultures also maintain both non‐neuronal cell types and the surrounding extracellular matrix. The interface method has been widely used for slice cultures, in which brain slices are placed on semiporous polytetrafluoroethylene (PTFE) membranes. However, a low optical transparency of PTFE membrane makes it difficult to perform live imaging of deep regions of slice cultures using an inverted microscope. To overcome the issue, we evaluated the suitability of using collagen membranes for slice cultures, especially focusing on live imaging of the cellular dynamics of green fluorescent protein (GFP)‐expressing microglia.MethodsEntorhinohippocampal slices were cultured on either collagen or PTFE membranes. The influence of membrane type on the ability to observe deep regions of slice cultures was examined by live imaging using an inverted microscope.ResultsCollagen membranes were thinner and had better optical transparency compared with PTFE membranes. There were no differences in cell viability, density of neurons or microglia. The densify of visible short branches of microglia in live imaging was higher in collagen membranes than PTFE membranes.ConclusionCollagen membranes are suitable for live imaging of cellular dynamics in slice cultures using an inverted microscope.
Green composites based on avocado seed starch and nano‐ and micro‐scale cellulose
Authors: Fu Denghao , Netravali Anil N. 
Published: August 2020

AbstractNonedible avocado (Persea americana) seed starch (AVS) was developed as resin for green composites. AVS was cross‐linked using a green cross‐linker, 1,2,3,4‐butane tetracarboxylic acid to prepare a rigid thermoset resin having improved water stability. Two cellulose fiber reinforcements, micro‐fibrillated cellulose (MFC) with average diameter of 50 nm and a common weed velvet leaf (Abutilon therophrasti) stem‐derived microfibers (VLF) with average diameter of 12 μm, were used to fabricate green composites by solution casting method. MFC/AVS and VLF/AVS green composites were characterized for tensile, thermal, and dynamic mechanical properties and water absorption. Results showed that mechanical properties of VLF/AVS composites were comparable to MFC/AVS composites at same volume fraction. The tensile strength, fracture strain, and Young's modulus of AVS composites with 30% VLF microfibers and 15% sorbitol (plasticizer) were 27.8 MPa, 10.2%, and 1614 MPa, respectively. Both strength (36.7 MPa) and Young's modulus (2303 MPa) increased significantly with 40% VLF fiber content. Good reinforcement by VLF microfibers was realized due to its high aspect ratio and good dispersity in AVS matrix. It would be advantageous to replace MFC with inexpensive VLF to reduce the cost. These composites may be further reinforced to fabricate hybrid green composites using continuous fibers.
The effect of job demands on health and work outcomes: A longitudinal study among Malaysian employees
Authors: Muhamad Nasharudin Nurfazreen Aina , Idris Mohd Awang , Young Loh M. 
Published: August 2020

AbstractThe purpose of the current study was to investigate the impact of job demands on health and work outcomes among Malaysian workers. We hypothesized that job demands (i.e., emotional demands and physical demands) would predict future work‐related burnout and work engagement, in turn affecting sleep problems and job performance (in‐role, extra‐role). A longitudinal two‐wave survey was conducted among Malaysian workers and valid data from 345 participants were analyzed using structural equation modeling. The results revealed that work‐related burnout predicts sleep problems while work engagement increased employees' job performance over time. Overall, the current study highlights the importance of specific job demands (i.e., emotional demands and physical demands) that specifically affect health‐related behavior and work‐related behavior among workers.
Partial inertion as basis of safety for pharmaceutical operations involving highly ignition sensitive powders and modeling combustion properties as a function of oxygen concentration
Authors: Toth Michael , Orella Charles , Roth Megan , Muzzio Dan , Fisher Elizabeth , Vickery Thomas , Bachert Don , Stone Shane , Bader Josh 
Published: August 2020

AbstractPharmaceutical operations often require inertion or other suitable explosion protection systems when handling highly ignition sensitive materials. Regulating bodies typically require full inertion, which may be difficult and expensive to maintain. This work measured the influence of oxygen concentration on the values of the minimum ignition energy (MIE) as well as the explosion severity (Kst and Pmax) for several of the most easily ignitable pharmaceutical powders. We found a significant increase in the MIE and decreases in the Kst and Pmax by reducing the oxygen level to 12% to 15% v/v. The changes in MIE and explosion severity mean that partial inertion along with control of static should provide a satisfactory basis of safety for most unit operations handling these powders. We share these results to encourage others to examine the behavior of similar organic powders. Further, we have used the adiabatic flame temperature from combustion calculations to model the Pmax, limiting oxygen concentration, and MIE at reduced oxygen concentrations, and find very good agreement with the experimental values. This modeling can be a useful tool as a safe and economical alternative to testing when material is not available or for highly potent/toxic materials where testing is not preferred to avoid personnel exposure.
Structure‐triggered asymptotical synchronization for nonidentical generalized stochastic systems with Markovian jumping parameter based on sliding mode control
Authors: Zhang Xin , Ding Xiangwu , Zhou Wuneng , Sun Yuqing 
Published: August 2020

SummaryIn this paper, the problem of structure‐triggered asymptotical synchronization for nonidentical generalized stochastic systems with Markovian jumping parameter is investigated. Firstly, by designing a structure‐triggered communication scheme, the optimal master system can be chosen for the slave system to synchronize. Furthermore, when the master system selected for the first time fails, the system can be promptly chosen again. Secondly, based on the sliding mode control approach and the linear matrix inequality technique, some sufficient conditions for synchronization of the nonidentical generalized stochastic systems are obtained. Finally, the effectiveness of the method is illustrated by two numerical examples.
Nano‐Platinum Catalysts Supported by Carbon Aerogel Microsphere with Adjustable Pore Size Tuned by PEG‐200 for Oxygen Reduction Reaction
Authors: Zeng Min , Wang Chao‐Yang , Su Lei , Luo Zhi‐Hui , Wu Jian‐Kun , Yi Yong 
Published: August 2020

AbstractCarbon‐supported nano‐platinum catalyst is extensively used as electrocatalyst in proton exchange membrane fuel cells (PEMFCs) due to its high catalytic activity towards the oxygen reduction reaction (ORR). phloroglucinol‐resorcinol‐formaldehyde carbon aerogel (CPRF) microsphere with adjustable pore sizes can be prepared by adding template, PEG‐200, on the basis of inverse micro emulsion method. Without cumbersome solvent exchange and supercritical drying, CPRF microspheres with a unique 3D structure can be obtained, which has a suitable microporous structure (10‐35 nm) and applicable mesoporous size (∼20 nm). As the support of the platinum, the CPRF microspheres with high specific surface area (798.3 m2 g−1) show excellent catalytic activity for ORR in alkaline electrolytes. The initial electrochemical active surface area and mass activity of the prepared Pt/CPRF are 2.5 and 2.7 times higher than that of commercial Pt/C respectively. After the accelerated durability test (ADT), the Pt/CPRF still keeps a stable electrochemical active surface area and mass activity up to 56 m2 g−1 and 0.11 A mg−1, while the commercial Pt/C lost to 42.8 m2 g−1 and 0.02 A mg−1. The stability of the Pt/CPRF shows about 5.5 times enhancement for ORR compared to commercial Pt/C.
Revealing Nanoscale Chemical Heterogeneities in Polycrystalline Mo‐BiVO4 Thin Films
Authors: Eichhorn Johanna , Reyes‐Lillo Sebastian E. , Roychoudhury Subhayan , Sallis Shawn , Weis Johannes , Larson David M. , Cooper Jason K. , Sharp Ian D. , Prendergast David , Toma Francesca M. 
Published: August 2020

AbstractThe activity of polycrystalline thin film photoelectrodes is impacted by local variations of the material properties due to the exposure of different crystal facets and the presence of grain/domain boundaries. Here a multi‐modal approach is applied to correlate nanoscale heterogeneities in chemical composition and electronic structure with nanoscale morphology in polycrystalline Mo‐BiVO4. By using scanning transmission X‐ray microscopy, the characteristic structure of polycrystalline film is used to disentangle the different X‐ray absorption spectra corresponding to grain centers and grain boundaries. Comparing both spectra reveals phase segregation of V2O5 at grain boundaries of Mo‐BiVO4 thin films, which is further supported by X‐ray photoelectron spectroscopy and many‐body density functional theory calculations. Theoretical calculations also enable to predict the X‐ray absorption spectral fingerprint of polarons in Mo‐BiVO4. After photo‐electrochemical operation, the degraded Mo‐BiVO4 films show similar grain center and grain boundary spectra indicating V2O5 dissolution in the course of the reaction. Overall, these findings provide valuable insights into the degradation mechanism and the impact of material heterogeneities on the material performance and stability of polycrystalline photoelectrodes.
Privacy and security constraints for code contributions
Authors: Andrade Rodrigo , Borba Paulo 
Published: August 2020

SummaryIn collaborative software development, developers submit their contributions to repositories that are used to integrate code from various collaborators. To avoid privacy and security issues, code contributions are often reviewed before integration. Although careful manual code review can detect such issues, it might be time‐consuming, expensive, and error‐prone. Automatic analysis tools can also detect privacy and security issues, but they often demand significant developer effort, or are domain specific, considering fixed framework specific vulnerability sources and sinks. To reduce these problems, in this paper we propose the Salvum policy language to support the specification of constraints that help to protect sensitive information from being inadvertently accessed by specific code contributions. We implement a tool that automatically checks Salvum policies for systems of different technical domains. We also investigate whether Salvum can find policy violations for a number of open‐source projects. We find evidence that Salvum helps to detect violations even for well‐supported and highly active projects. Moreover, our tool helps to find 80 violations in benchmark projects.
Integrierte Gesundheitsberichterstattung auf Landes- und kommunaler Ebene: Initiativen und Ansätze der letzten 20 Jahre
Authors: Trojan Alf 
Published: August 2020

ZusammenfassungDie Ottawa-Charta von 1986 schuf ein neues Paradigma der Gesundheitsförderung, in dem Konzepte wie intersektorale Politik, Determinanten der Gesundheit und Vermitteln und Vernetzen eine wichtige Rolle spielen. In diesem Rahmen entstand die Forderung, dass Gesundheitsberichterstattung (GBE) in einer „integrierten“ Form zu erbringen sei, also Daten aus ganz verschiedenen Politiksektoren enthalten sollte, in denen Determinanten der Gesundheit zu finden sind. In diesem Beitrag soll der Frage nachgegangen werden, ob es im deutschsprachigen Raum auf kommunaler und Landesebene explizite Konzepte und eine öffentlich kommunizierte Praxis integrierter GBE gibt. Dazu wurde eine explorative Internetrecherche durchgeführt, ergänzt um E‑Mail-Anfragen bei Schlüsselpersonen der Projekte.Es wurden 8 Projekte identifiziert: 4 davon repräsentieren kommunale bzw. städtische integrierte Berichterstattung; in Nordrhein-Westfalen gibt es 2 Initiativen von Landesbehörden, die sich auf die kommunale Berichterstattung beziehen; in Berlin und im Burgenland (Österreich) geht es um integrierte Berichterstattung auf der Bundeslandebene. Die Projekte werden in stark komprimierter Form vorgestellt. Hauptlimitationen der explorativen Recherche sind die Beschränkung auf explizit als „integriert“ bezeichnete Berichterstattung und die eng eingeschränkten Suchbegriffe.Ein positiver Befund ist, dass es einige gute Indikatorenkonzepte, gesetzliche Rahmenbedingungen und förderliche Faktoren, wie z. B. wissenschaftliche Unterstützung, gibt. An der konkreten Umsetzung integrierter GBE mangelt es aber noch. Mögliche Hürden sind dabei die Komplexität der Programme, fehlende finanzielle, personelle und fachliche Ressourcen, organisatorische und methodische Probleme sowie Ängste und Vorurteile. In verschiedenen Beispielen konnten diese aber überwunden werden. Der Leitfaden Gute Praxis Gesundheitsberichterstattung stützt – explizit, aber etwas zu versteckt – die Forderung nach integrierter Berichterstattung.