bluuebunny/crossref_metadata_2025 huggingface dataset:
High‐gain three‐phase current‐fed push–pull DC–DC converter
Authors: da Costa André Elias Lucena , Andersen Romero Leandro
Published: November 2019

In this study, a new three‐phase current‐fed push–pull DC–DC converter with high‐gain capability was proposed. The proposed circuit has the advantages of three‐phase converters and the push–pull converter circuit, with small volume and a simplified gate drive circuit with switches connected to the same reference. The converter was analysed for operation in continuous and discontinuous conduction modes. The analysis includes a description of the topological stage, theoretical waveforms, deduction of the voltage gains and the expressions for its practical design. To validate the theoretical analysis, a 700 W prototype was built and tested with an input voltage of 40 V, an output voltage of 400 V and a switching frequency of 40 kHz. Despite using a unity transformer turns ratio, the prototype had an experimental gain of ∼10, which makes the proposed converter suitable for applications as renewable energy sources systems.
New method for determining the optimum fluid temperature when heating pressure thick-walled components with openings
Authors: Taler Dawid , Dzierwa Piotr , Taler Jan
Published: November 2019

A new approximate method of optimum heating cylindrical pressure elements weakened by openings was proposed. Optimum variations in fluid temperature when heating the pressure component were determined from the condition that the total circumferential stress at the edge of the opening, resulting from the thermal load and pressure is equal to the allowable stress. The allowable stress is determined from the Wöhler fatigue diagram for a given number of start-ups and shutdowns of a power unit from the cold state. Optimum temperature changes are difficult to estimate at the beginning of the heating, usingboth exact analytical and numerical methods. In case of analytical methods, this is due to the very slow convergence of a series for near-zero time in the exact solution. In this paper, the optimum temperature changes of the fluid at the beginning of heating were determined using the heat balance integralmethod (HBIM). This method makes it possible to determine with high accuracy the temperature of the fluid for times close to zero, i.e., at the beginning of the heating process. In the second stage of heating, the optimum fluid temperature was determined on the assumption of a quasi-steady temperature field in the pressure element.
Numerical model of biological tissue heating using the models of bio–heat transfer with delays
Authors: Majchrzak Ewa , Mochnacki Bohdan
Published: November 2019

The numerical model of thermal processes in domain of biological tissue subjected to an external heat source is discussed. The model presented is based on the second order dual–phase–lag equation (DPLE) in which the relaxation time and thermalization time thermalization time
(τq and τT) are tak n into account. In this paper the homogeneous, cylindrical skin tissue domain is considered. The most important aim of the research is to compare the results obtained using the classical model (the first-orderDPLE) with the numerical solution resulting from the higher order form of this equation. At the stage of numerical computations the Finite Difference Method (FDM) is applied. In the final part of the paper the examples of computations are shown.
Meshing strategy for bifurcation arteries in the context of blood flow simulation accuracy
Authors: Lewandowska Natalia , Mosiężny Jędrzej
Published: November 2019

The study presents a mesh dependency study for a carotid artery bifurcation geometry of a real-life specimen. The results of time-averaged velocity profiles at artery control surfaces and wall shear stresses are compared between a set of structured and unstructured meshes, with varying non–dimensional boundary layer first element thickness (y+) parameter. A set of four meshes in total is considered: a full–hexagonal structured mesh, an unstructured tetrahedral mesh with prism inflation layer, both created for y+=1 and y+=30. Apart from numerical results, overall mesh creation work time, overall analysisstability are compared with the mesh quality results: cell non–orthogonality, cell skew and aspect ratio. Numerical results are validated against results of real–life CT examination performed in Poznań Medical University.
Effect of inserted sphere size on heat transfer characteristics of FCC structured pebble bed in a HTGR
Authors: Chen Leisheng , Lee Jaeyoung
Published: November 2019

Hot spots appearing in an operating high temperature gas-cooled reactor (HTGR) core have been considered as the most possible reason leading to a severe accident like fission production releasing to the environment, therefore, investigation on their positions and thus seeking ways to reduce the possibility of their appearance have attracted scientists’ attention. In our previous studies, heat transfercharacteristics of a face–centered–cubic (FCC) structured pebble–bed have been discussed,and a correlation on heat transfer coefficient with Reynolds number was presented. In this study, a method, placing a small sphere in thegap area, which is able to enhance the convective heat transfer wasproposed and the effect verifiedas well. The influence of the sphere diameter on heat transfer performances wasinvestigated in details. It is concluded through results analysis that (1) inserted sphere lowered thelocal surface temperature of adjacent pebbles by varying surrounding flow field;(2) maximum velocity of the fluid and average heat transfer coefficientincreased with sphere diameter, particularly, comparing with no small sphere case, 12.95% enhancement was achieved. Such findings may provide dataand information for reactor designers, andhelp to develop a safer HTGR pebble–bedcore.
Numerical and experimental researches of thermal energy storage processesduring phase transformations of phase change materials with nanoparticles
Authors: Gorobets Valery , Antypov Ievgen , Bohdan Yurii , Trokhaniak Viktor
Published: November 2019

It is evident that nowadays materials with phase or chemical transformations are significantly considered to be in surpassing demand in the society being used for accumulating thermal energy. Furthermore, this usage leads to the process of increasing accumulated thermal energy per unit mass concentration to be achieved in a much beneficial and reliable manner. In comparison to these materials, well-known and widely–used solid and liquid ones are mainly associated with productivity and efficiencylosses. One of the methods, having desirable attributes for substantial enhancement in the energy productivity of phase change materials is proved to be the addition of solid nanoparticles with a large coefficient of thermal conductivity.

This work focuses on numerical and experimental investigation the influence of nanoparticles of various materials and sizes on the processes of thermal energy storage in paraffin. In particular, the proceeding data of the thermophysical properties of paraffin with nanoparticles as being found by the optical spectroscopy method. Moreover, due to comprehensive results in experimental and numerical studies, the heat accumulating capacity of the phase change materials, as well as the dynamics and profile of the melting boundary around cylindrical heat sources were reported to be determined. Besides, the comparison of heatstorage capacity for phase change materials with and without nanoparticles is managed.
CFD analysis of steam superheater, transient state
Authors: Granda Mariusz , Trojan Marcin , Taler Jan
Published: November 2019

Nowadays, industry requirements referring to the optimization, not only demand better efficiency ordurability but also the lower total cost of the project. Maximum temperatures, allowablestress and economics determine materials used during the engineering process. Moreover, different materials in different parts of superheater can be used. Regarding the steady–state, calculations can be derived without major difficulties but transient–state is a much more complex issue, where Computational Fluid Dynamics can be applied. CFD as an engineering tool, that gives a better understanding of the problem, is more and more popular during the optimization process. Appropriate knowledge about heat transfer, fluid dynamics, finite element method is required to find the solution to the given question. The paper presents a CFD analysis of the transient-state of the steam boiler superheater when attemperator is running. Temperature distribution of the steam, flue gas and maximum wall temperature were determined.
Analysis Of Field Synergy In Bottom Heated Lid Driven Cubical Cavity
Authors: Rani H.P. , Narayana V. , Rameshwar Y.
Published: November 2019

This study presents an innovative visualization tool for the analysis of the mixed convection in a lid-driven air filled cubical cavity heated from below. The total energy of the flow in the cavity isvisualized based on the energy stream functions or energy streamlines. Also the heat transfer enhancement in the cavity is presented with an analogy between conduction and convection, namely, the field synergy principle. Flow is assumed to be driven by the vertical temperature gradient and by the top lid of the cavity, which is assumed to slide on its own plane at a uniform speed. The top and bottom walls are assumed to be isothermal and all other walls are thermally insulated. Non dimensional governing equations of this problem are solved by using the finite volume method. Established open source CFD package OpenFOAM is utilized to investigate the flow with respect to the control parameters arising in the system. The nonlinear terms arising in the governing equations are discretized with the NVD schemes. The convection differencing schemes namely, UPWIND, QUICK, SUPERBEE and SFCD discussed and are used to simulate the flow using MPI code. It is observed that the computational cost for all the differencing schemes get reduced tremendously when the MPI code is implemented. Also SFCD scheme gave the Nuseelt number values close to those available in the literature. Extensive numerical flow visualization is conducted for the Reynolds number (Re = 100, 400, 1000) and the Richardson number (Ri = 0.001, 1, 10), which categorize the free and forced convective flow, respectively. It is observed that for a fixed value of Re, as Ri increases, the average Nusselt number (Nu¯), decreases. This shows that the natural convection starts to prevail with an increasing of Ri. But, for a fixed Ri, as Re increases (Nu¯) increases and the forced convection mode becomes dominant, leading to a chaotic flow. Plots demonstrating the influences of Re and Ri in termsof the contours of the fluid streamlines, isotherms, vortex corelines, and field synergy principle. The synergy angle of buoyant-aiding flow is high while the buoyant-opposing flow is significantly less than that of forced convection flow.
Coupled System of Boundary Value Problems by Galerkin Method with Cubic B-Splines
Authors: Kasi Viswanadham K.N.S
Published: November 2019

Coupled system of second order linear and nonlinear boundary value problems occur in various fields of Science and Engineering including heat and mass transfer. In the formulation of the problem, any one of 81 possible types of boundary conditions may occur. These 81 possible boundary conditions are written as a combination of four boundary conditions. To solve a coupled system of boundary value problem with these converted boundary conditions, a Galerkin method with cubic Bsplines as basis functions has been developed. The basis functions have been redefined into a new set of basis functions which vanish on the boundary. The nonlinear boundary value problems are solved with the help of quasilinearization technique. Several linear and nonlinear boundary value problems are presented to test the efficiency of the proposed method and found that numerical results obtained by the present method are in good agreement with the exact solutions available in the literature.
Numerical simulation of different pollution sources in an urban environment
Authors: Fernández Gonzalo , Rezzano Nicolás , D’Angelo Mauro , Mendina Mariana
Published: November 2019

A model for representing different pollution sources in an Urban Environment is presented in this paper. An in-house incompressible flow solver called caffa3d.MBRi was used and modified in order to include the sources from chimneys, cars and houses to compute the dispersion of different pollutants simultaneously. Moreover, different urban domains with a wide variety of sources were simulated reaching promising results.
Control of smoke flow using a jet-fan in an underground car park
Authors: Borowski Marek , Jaszczur Marek , Karch Michal , Burdzy Tomasz
Published: November 2019

Ventilation systems are used to provide ventilation for covered car parks and to control the smoke in the event of fire. In this paper the interaction between the fire ceiling jet and the flow driven by jet-fans is studied using CFD simulations. There is a number of parameters that can affect the flow of smoke that need to be considered. To avoid mistakes, fluid flow visualisation is highly required as well as in order to directly compare the different design variants. One of the best option to make flow analysis is to performed Computational Fluid Dynamics simulations (CFD). By CFD it is possible to detailed analyse and keep control of the flow of fluid, heat transfer and other related phenomena. It also helps predict the contamination level of Carbon Monoxide, heat and smoke intensity and distribution. In this study, CFD simulations were used to design, test and compare different design of a fire ventilation system. The research drew attention to the location of jet-fan type fans. The main objective of the study was to assess the impact of jet-fans on fire and to check if it is possible to evacuate people from the garage in less than 10 minutes. The simulation results emphasize the important location of the different elements on the functionality and efficiency of a fire protection system. Due to the evacuation of people from the garage, the simulation results suggest a 10 minute safety time for evacuation. During this period, high visibility and oxygen concentration, as well as low temperature allow for rapid evacuation.
Analyse de la validité du contenu et de la qualité formelle des questions isolées des épreuves classantes nationales informatisées (ECNi) de l’année universitaire 2015–2016
Authors: Pers Yves-Marie , Marais Clémentine , Lambert Philippe , Jeandel Claude , Chanques Gérald , Szwarc Ilan , Faillie Jean-Luc , Mathieu Olivier , Le Quintrec Moglie
Published: November 2019

Contexte : Les premières épreuves classantes nationales informatisées (ECNi) clôturant le deuxième cycle des études médicales en France ont eu lieu en juin 2016 et ont comporté des dossiers cliniques progressifs (DCP), des questions isolées (QI), ainsi qu’une épreuve de lecture critique d’articles (LCA). Les QI représentaient une nouveauté de cet examen puisque les DCP et la LCA étaient utilisés depuis 2004. But : Analyse de la validité du contenu et de la qualité formelle des QI des premières épreuves ECNi. Méthodes : Un questionnaire contenant les critères docimologiques à recueillir a été défini et validé au préalable. Les 120 QI de l’ECNi 2016 ont été analysées par un binôme indépendant. Les discordances entre les évaluateurs ont été interprétées. Toutes les analyses ont été colligées sur tableur Excel puis les statistiques ont été réalisées sur Graphpad Prism version 6 et Stata v12. Résultats : Les rédacteurs des QI ont majoritairement respecté les consignes de forme. Les niveaux d’habiletés intellectuelles requis concernaient majoritairement les processus de mémorisation, de simple récupération de l’information et de compréhension (82 % des QI). Dans 7 à 23 % des QI, l’utilisation de distracteurs était jugée inappropriée. Une prédominance de QI portait sur les disciplines médicales (72,5 %). L’unité d’enseignement (« Circulation – Métabolismes ») était la plus représentée (26 %). Les discordances étaient faibles (6,2 % des évaluations). Conclusion : Il s’agit de la première analyse de la validité du contenu et de la qualité formelle des QI des ECNi. Leur format de rédaction a été largement respecté par les auteurs. Elles ont peu fait appel à des processus de raisonnement complexe. Il semblerait utile de favoriser les courtes vignettes cliniques pour améliorer cet aspect.
Was ist Ihre Lieblings-betätigung? – Betätigungsorientierte Berufspraxis
Authors: Völler Stefanie
Published: November 2019

Stefanie Völler untersuchte in ihrer Masterarbeit, welchen Herausforderungen Ergotherapeuten bei der Umsetzung der betätigungsorientierten Therapie begegnen. Dabei hat sie erkannt, wie wichtig die begriffliche Auseinandersetzung mit „Betätigung“ im Berufsalltag ist.
Die persönliche Handlungsgeschichte erfassen – Assessment: Activity Card Sort (ACS)
Authors: Trickes Jutta , Hörnle Jutta
Published: November 2019

Mit dem Instrument „Activity Card Sort“ können Ergotherapeuten die Partizipation von 60- bis 85-Jährigen in verschiedenen Lebens-bereichen erfassen. Es eignet sich für Gesunde und für Personen nach Schlaganfall. Mit den Fotokarten lassen sich Handlungen einschätzen und Ziele definieren.
Kompressionstherapie bei Patienten mit Ulcus cruris – Welche Kosten entstehen wirklich?
Authors: Dissemond Joachim , Protz Kerstin , Moelleken Maurice , Kröger Knut
Published: November 2019

Hintergrund Patienten mit Ulcus cruris haben häufig ausgeprägte Ödeme der unteren Extremitäten, die im Rahmen einer erfolgreichen Wundversorgung behandelt werden müssen. Die hierfür notwendigen Kompressionstherapien werden heute in Deutschland oft mit sehr fehler- und zeitaufwendigen Verbänden mit Kurzzugbinden durchgeführt. Mehrkomponentensysteme, adaptive Kompressionsbandagen und Ulkus-Strumpfsysteme sind neuere, deutlich weniger fehleranfällige Therapieoptionen. Neben dem oft nicht vorhandenen Wissen werden auch die scheinbar hohen Kosten als Grund für die nicht vorgenommene Verordnung dieser Materialien angeführt. Es war daher das Ziel unserer Untersuchung, die Kosten der verschiedenen Therapieoptionen im ambulanten und stationären Sektor differenziert darzustellen.

Methoden Für die ökonomischen Berechnungen wurden sowohl die Material- als auch die Personalkosten für verschiedene Szenarien berücksichtigt.

Ergebnisse Es zeigte sich, dass durch die kontinuierliche Kompressionstherapie im stationären Bereich Kosten von 5,29 Euro bis 18,50 Euro pro Tag anfallen. Für die ambulante Versorgung wurden Kosten von 2,29 Euro bis 34,29 Euro pro Tag ermittelt. Die verschiedenen Konstellationen der Kompressionstherapie können somit nicht nur medizinisch, sondern auch wirtschaftlich unterschiedlich sinnvoll sein.

Folgerung Als Konsequenz dieser Daten sollten sowohl die verschiedenen Materialien als auch die ökonomischen Aspekte der Kompressionstherapie bei Patienten mit Ulcus cruris den Therapeuten bekannt sein. Diese Therapieoptionen sollten dann unter Einbeziehung individueller Faktoren und orientiert an den Bedürfnissen und Fähigkeiten der Patienten verordnet und durchgeführt werden.
Social influences in cross-border entrepreneurial migration policy
Authors: Kautto Daria
Published: November 2019

This paper addresses the possibilities for public policy to stimulate the entrepreneurial perceptions of individuals by leveraging micro-level social influences produced by migrant entrepreneurs. As opposed to the conventional stand according to which entrepreneurial ecosystems can be stimulated by financial, regulative, cognitive and normative mechanisms of influence, the present study suggests that socio-psychological influences enacted by exogenous policy intervention can be used as a mechanism for shifting the entrepreneurial perceptions of individuals. Cross-border entrepreneurial migration is proposed as an instrument for enacting these socio-psychological influences and enabling public policy to benefit from the distinctively different entrepreneurial behaviors of migrant entrepreneurs and local individuals in the host country. The study offers substantial policy implications by extending the theoretical reasoning guiding the stimulation of entrepreneurial ecosystems through public policy intervention, providing discussion of opportunity perception in cross-border context, and offering an alternative socio-economic perspective on the role of migrant entrepreneurs in the economic life of host countries.
Origin of external quantum efficiency roll-off in 4,4′-bis[(N-carbazole)styryl]biphenyl (BSBCz)-based inverted organic light emitting diode under high pulsed electrical excitation
Authors: Bencheikh F. , Sandanayaka A. S. D. , Fukunaga T. , Matsushima T. , Adachi C.
Published: November 2019

Laser diodes based on organic semiconductor materials have high threshold current densities that require the suppression of various inherent loss processes. One way to study such loss processes is to analyze the external quantum efficiency (EQE) roll-off in organic light-emitting diodes (OLEDs). In this work, we used electrical simulations to analyze the origin of the experimental EQE roll-off of an OLED based on 4,4′-bis[(N-carbazole)styryl]biphenyl (BSBCz) under extremely high current injection (∼1 kA/cm2). We considered various singlet exciton annihilations and quenching processes (i.e., singlet-singlet annihilation, singlet-triplet annihilation, singlet-polaron annihilation, singlet-heat quenching, and electric field quenching of singlet excitons). These results showed that the EQE roll-off can be attributed to Joule heating and/or singlet-triplet annihilation and/or the dissociation of singlet excitons under a high applied electric field. The electric field quenching of singlet excitons was confirmed by a field-induced photoluminescence (PL) quenching experiment. By applying an electric field-induced charge dissociation model to both the EQE and field-induced PL quenching, we estimated the singlet exciton binding energy of a BSBCz film to be in the range of 0.64–0.71 eV.
Particle charge in PK-4 dc discharge from ground-based and microgravity experiments
Authors: Antonova T. , Khrapak S. A. , Pustylnik M. Y. , Rubin-Zuzic M. , Thomas H. M. , Lipaev A. M. , Usachev A. D. , Molotkov V. I. , Thoma M. H.
Published: November 2019

The charge of microparticles immersed in the dc discharge of the Plasmakristall-4 experimental facility has been estimated using the particle velocities from experiments performed on Earth and under microgravity conditions on the International Space Station. The theoretical model used for these estimates is based on the balance of the forces acting on a single particle in the discharge. The model takes into account the radial dependence of the discharge parameters and describes reasonably well the experimental measurements.
Effect of KOH passivation for top-down fabricated InGaN nanowire light emitting diodes
Authors: Hartensveld Matthew , Ouin Gildas , Liu Cheng , Zhang Jing
Published: November 2019

Gallium nitride (GaN) nanowire (NW) light emitting diodes (LEDs) are promising candidates for microdisplay applications due to smaller dimensions and potential for novel integration approaches. For the commonly adopted top-down GaN NW fabrication, the required dry etching steps tend to result in surface states, leading to reduced radiative recombination rates in LEDs. To passivate the surface and tune the diameter of the NWs, hydroxyl-based chemicals such as potassium hydroxide (KOH) are widely used to treat the surface of these nanostructures. However, studies on the effects of temperature, concentration, and the damage recovery aspects of hydroxyl etching of GaN NWs are very scarce. These etching parameters are of great importance for device performance. Here, these effects are explored thoroughly with a focus on the correlation of InGaN/GaN NW LED performances to KOH etching temperature, concentration, and time, together with a fundamental crystallographic analysis. The KOH concentration resulting in total removal of the NW base tapering and a collimated etch profile for InGaN NW LEDs was found to be 0.8 wt. % at a temperature of 45 °C. A 20 min etch at 23 °C with a 0.1 wt. % KOH concentration will remove surface states from a top-down fabricated NW LED to recover up to 90% of the peak photoluminescence (PL) intensity lost by the dry etch step. The oscillation behavior in PL intensity with regard to the KOH etch time has been demonstrated in InGaN/GaN NW LEDs for the first time, which will shed light upon the design and passivation of these devices for microdisplays.
Range-separation and the multiple radii functional approximation inspired by the strongly interacting limit of density functional theory
Authors: Gould Tim , Vuckovic Stefan
Published: November 2019

The strongly interacting limit of density functional theory has attracted considerable attention recently due to its ability to deal with the difficult strong correlation problem. Recent work [S. Vuckovic and P. Gori-Giorgi, J. Phys. Chem. Lett. 8, 2799–2805 (2017)] introduced the “multiple radii functional” (MRF) approximation, inspired by this limit, which is designed to work well for strong correlations between dissociated fragments. Here, we analyze the MRF in exactly solvable one-dimensional molecules to uncover how it matches and deviates from exact results and use range-separation of the Coulomb potential in both exact and approximate theory to explore how this varies in space. We show that range-separated treatment of the MRF can offer advantages over a full treatment, by using MRF for short-ranged and/or midranged interactions only. Our work opens a path to new approximations incorporating the MRF, amongst other ingredients.
Effect of low-frequency alternating current poling on 5-mm-thick 0.7Pb(Mg1/3Nb2/3)O3-0.3PbTiO3 single crystals
Authors: Luo Chengtao , Wan Haotian , Chang Wei-Yi , Yamashita Yohachi , Paterson Alisa R. , Jones Jacob , Jiang Xiaoning
Published: November 2019

Alternating current (electric field) poling (ACP) was applied on [001]-oriented 0.7Pb(Mg1/3Nb2/3)O3-0.3PbTiO3 (PMN-0.3PT) single crystal samples with dimensions of 5 × 1.25 × 1.25 mm3 (with electrodes on the 1.25 × 1.25 mm2 surfaces), and the influence of ACP frequency (fACP) was studied. Compared to those from traditional direct (electric field) poling samples, the piezoelectric coefficient (d33) and free dielectric constant (εT33/ε0) of ACP samples could gain up to a 67% increase to 3200 pC/N and 10 500, respectively. The influence of fACP was studied on two main aspects: saturated properties and dynamic saturation process. In general, ACP samples with lower fACP had higher saturated d33, εT33/ε0, and coupling factor k33, as well as lower dielectric loss and faster saturation speed. The ACP dynamics during the saturation process were studied by measuring the polarization-vs-electric field hysteresis loops (P-E loops). The P-E loops illustrated that the coercive field of ACP samples could be further tuned from 1.84 kV/cm to 3.03 kV/cm by changing fACP (0.1–10 Hz). This work demonstrated the enormous potential of ACP optimization in relaxor-PT single crystal-based low-frequency transducer applications.
Mechanical and optical response of polymethylpentene under dynamic compression
Authors: Barmore L. M. , Knudson M. D.
Published: November 2019

Polymethylpentene, commonly referred to by its trade name TPX (Mitsui Chemicals, Inc.), is a thermoplastic polymer that has the potential to be a useful window material for dynamic compression experiments. For such experiments, an optically transparent or a low x-ray absorptive window is often used to maintain stress within the sample during compression. TPX can be used as a low-impedance optical and x-ray window due to its good transmittance in most parts of the electromagnetic spectrum, very low density (0.83 g/cm3), and low x-ray absorption. In dynamic compression experiments, interferometry can be used to determine the particle velocity at the interface between the sample and window. However, velocimetry measures the rate of change of the optical path length, commonly referred to as the apparent particle velocity. An experimentally determined window correction factor is needed to ascertain the actual particle velocity from the measured apparent velocity. Here, we present the results of a series of dynamic compression experiments from 1 to 31 GPa designed to characterize the mechanical and optical response of TPX, determine the range of stresses over which TPX is transparent, and determine the window correction factor. The index of refraction was found to be essentially linear in density, resulting in a simple constant correction factor. TPX was found to remain largely transparent over the entire stress range examined.
Use of pre-exposure prophylaxis increases the odds of condomless anal sex among young men who have sex with men (MSM) of colour
Authors: Crosby Richard A. , Kipke Michele D. , Kubicek Katrina
Published: November 2019

This study tested the hypothesis that people using pre-exposure prophylaxis (PrEP) would be more likely to report condomless anal sex than those not taking PrEP. Data were from an ongoing study conducted with a cohort of Black and Latino young men who have sex with men (YMSM) recruited in Los Angeles (CA, USA). Of the 399 YMSM in the sample, 14% were currently using PrEP. Using three different measures of condom use, across two different recall periods all except one test result supported an inverse relationship between PrEP and condom use for anal sex. Tests of a risk index provided further significant findings supporting this hypothesis.
How collective asperity detachments nucleate slip at frictional interfaces
Authors: de Geus Tom W. J. , Popović Marko , Ji Wencheng , Rosso Alberto , Wyart Matthieu
Published: November 2019

Sliding at a quasi-statically loaded frictional interface can occur via macroscopic slip events, which nucleate locally before propagating as rupture fronts very similar to fracture. We introduce a microscopic model of a frictional interface that includes asperity-level disorder, elastic interaction between local slip events, and inertia. For a perfectly flat and homogeneously loaded interface, we find that slip is nucleated by avalanches of asperity detachments of extension larger than a critical radius

A

c

governed by a Griffith criterion. We find that after slip, the density of asperities at a local distance to yielding

x

σ

presents a pseudogap

P

(

x

σ

)

∼

(

x

σ

)

θ

, where

θ

is a nonuniversal exponent that depends on the statistics of the disorder. This result makes a link between friction and the plasticity of amorphous materials where a pseudogap is also present. For friction, we find that a consequence is that stick–slip is an extremely slowly decaying finite-size effect, while the slip nucleation radius

A

c

diverges as a

θ

-dependent power law of the system size. We discuss how these predictions can be tested experimentally.
aPKCi triggers basal extrusion of luminal mammary epithelial cells by tuning contractility and vinculin localization at cell junctions
Authors: Villeneuve Clémentine , Lagoutte Emilie , de Plater Ludmilla , Mathieu Samuel , Manneville Jean-Baptiste , Maître Jean-Léon , Chavrier Philippe , Rossé Carine
Published: November 2019

Significance

This study shows that an oncogenic mammary epithelial cell surrounded by normal cells can extrude basally in vivo and invade surrounding tissues without formation of a primary tumor. Here, we show that overexpression of the key polarity protein atypical protein kinase C ι (aPKCi) is sufficient for triggering basally oriented epithelial cell extrusion and early cell invasion into the mammary gland stroma. Moreover, we highlight the importance of the difference between the mechanical properties of aPKCi-overexpressing cells and those of the normal surrounding cells associated with the decrease of vinculin at the cell junction, which triggers cell segregation, the first step toward promoting and controlling the direction of cell extrusion.
Crack engineering for the construction of arbitrary hierarchical architectures
Authors: Li Wanbo , Yu Miao , Sun Jing , Mochizuki Kentaro , Chen Siyu , Zheng Huanxi , Li Jiaqian , Yao Shuhuai , Wu Hongkai , Ong Beng S. , Kawata Satoshi , Wang Zuankai , Ren Kangning
Published: November 2019

Significance

Despite emerging breakthroughs in the achievement of numerous elegant biomimetic structures that impart fascinating functionalities, bioinspired materials still suffer from poor structural durability, chemical reliability, flexibility, and optical transparency, as well as unaffordable cost and low throughput, thus preventing their broad real-life applications. In striking contrast to conventional wisdom, we demonstrate that the usually avoided and detrimental elastic crack phenomenon can be translated into powerful configurable-crack engineering to achieve structures and functions that are impossible to realize even using state-of-the-art techniques. Our approach dramatically enriches the freedom and flexibility in the design of materials to mimic various natural living organisms and paves the road for translating nature’s inspirations into real-world applications.
Pre-trial screening using DNA diagnostics.
Authors: Sitepu B. , Laksono N. D. , Setiawati U. , Nur F. , Rahmaningsih M. , Anwar Y. , Widodo P. , Forster B. P. , Purba A. R.
Published: November 2019

DNA analysis provides an opportunity to screen for certain traits prior to field planting. This is particularly important in screening for shell thickness. The shell thickness gene (Sh) is probably the most valuable gene in oil palm breeding and commerce. Pre-field planting screening is important as selection for dura and tenera types can be made and (sterile) pisiferas may be eliminated, thus saving on time and land space. This also allows for more robust field trialling as dura and tenera types can be separated. Nursery seedlings offer a convenient phase in which to sample leaves, extract and analyse DNA, thus selections can be made before field planting. In addition to the Sh gene, screening for other important traits is now possible (e.g. virescens and mantled fruit). This chapter gives an overview of pre-trial screening using currently available DNA diagnostics, but this area of work is developing quickly and set to expand in the future. Practical details of the DNA protocols involved are not given as these are in another manual in this series (Anwar et al., 2019). DNA analyses can be carried out in-house or outsourced to DNA service laboratories.
Examining environmental constraints in sport: Spin characteristics of two cricket pitches with contrasting soil properties
Authors: Crowther Rian H. , Gorman Adam D. , Spratford Wayne A. , Sayers Mark G. , Kountouris Alex
Published: November 2019

In the sport of cricket, the pitch is an organic surface that represents an important environmental constraint. While the soil properties of the pitch are known to influence the pace and bounce of medium and fast deliveries, it is unknown how the soil constructs or the seam of the cricket ball affect the pace, bounce, and deviation of a spinning delivery. A specialised spin bowling machine was used to deliver 276 (139 wrist spin, 137 finger spin) spinning deliveries onto two cricket pitches with contrasting soil properties. The pitches included a bespoke international pitch (BIP; higher sand content at 43.28%) and a common Australian pitch (CAP; lower sand content at 7.44%). Results indicated that the BIP showed significantly slower reflection pace and larger deviation, compared to the CAP. Irrespective of the pitch type, when the seam of the ball impacted the pitch, there was a significantly slower reflection pace and larger deviation. The reflection properties of the BIP resembled that of a “spinning pitch” which can be used as a form of representative practice for conditions similar to those that may be experienced in India. The impact of the seam on the pitch surface significantly altered the reflection of the ball and should be considered in future cricket research.
Altitude‐induced effects on muscular metabolic stress and hypertrophy‐related factors after a resistance training session
Authors: Feriche Belen , Schoenfeld Brad J. , Bonitch‐Gongora Juan , de la Fuente Blanca , Almeida Filipa , Argüelles Javier , Benavente Cristina , Padial Paulino
Published: November 2019

This study examined the acute effects of exposure to moderate altitude on factors associated with muscular adaptations following whole‐body hypertrophy‐oriented resistance training (R T) sessions. Thirteen resistance‐trained males completed both counterbalanced standard hypertrophic R T sessions (3 sets × 10RM, 2 min rest) at moderate‐altitude (H; 2320 m asl) and under normoxic conditions (N; <700 m asl). Participants rested 72 h between training sessions. Before and after the exercise session, blood samples were obtained for determination of metabolites and ions (lactate, inorganic phosphate, liquid carbon dioxide and calcium) and hormones (testosterone and growth hormone). Session‐related performance and perception of effort (s‐RPE) were also monitored. Results showed no meaningful differences in performance or s‐RPE (8.5 ± 1.4 vs 8.6 ± 0.8 respectively for N and H; p = 0.603). All blood variables displayed statistically significant changes throughout the recovery period compared to basal levels (p < 0.05), except for the testosterone. However, no altitude effect was observed in maximal blood lactate, calcium or anabolic hormones (p > 0.05). The reduction observed in the liquid carbon dioxide concentration in H (21.11 ± 1.46 vs 16.19 ± 1.61 mmol·l−1) seems compatible with an increase in buffering capacity. Compared to N, inorganic phosphate displayed lower recovery values after the R T in H (2.89 ± 0.64 vs 2.23 ± 0.60 mg dl−1; p = 0.007). The results of this study do not support an accentuated effect of acute moderate terrestrial hypoxia on metabolic and hormonal factors linked to muscle growth during hypertrophic resistance training.
Mammalian muscle fibers may be simple as well as slow
Authors: Squire John M. , Luther Pradeep K.
Published: November 2019

Squire and Luther consider new evidence for a simple lattice structure in mammalian skeletal muscle.
High-Repetition-Rate and High-Beam-Quality Laser Pulses with 1.5MW Peak Power Generation from a Two-Stage Nd:YVO4 Amplifier*
Authors: He Qiu-Run , Guo Jing , Zhang Bao-Fu , Jiao Zhong-Xing
Published: November 2019

We develop a two-stage end-pumped Nd:YVO4 amplifier seeded by a passively Q-switched microchip laser. An average output power of 13.5 W with repetition rate up to 7 kHz and pulse duration of ∼1.24 ns is obtained, corresponding to a pump extraction efficiency of 16.1% (19.5% for the second stage) and peak power of ∼1.5 MW. The beam quality factors at maximum output power are measured to be

M
x
2

=
1.56

and

M
y
2

=
1.48

. We introduce an analytical model to estimate gain and beam quality after amplification. This model focuses on the influence of ratio of seed spot radius to pump spot radius when designing an amplifier. Moreover, our experiments reveal that the re-imaging system in the double-pass configuration can be used to enhance the beam quality.
Label-Free Microscopic Imaging Based on the Random Matrix Theory in Wavefront Shaping*
Authors: Yu Li-Qi , Xu Xin-Yu , Zhang Zhen-Feng , Feng Qi , Zhang Bin , Ding Ying-Chun , Liu Qiang
Published: November 2019

Wavefront shaping technology has mainly been applied to microscopic fluorescence imaging through turbid media, with the advantages of high resolution and imaging depth beyond the ballistic regime. However, fluorescence needs to be introduced extrinsically and the field of view is limited by memory effects. Here we propose a new method for microscopic imaging light transmission through turbid media, which has the advantages of label-free and discretional field of view size, based on transmission-matrix-based wavefront shaping and the random matrix theory. We also verify that a target of absorber behind the strong scattering media can be imaged with high resolution in the experiment. Our method opens a new avenue for the research and application of wavefront shaping.
Effective size separation of laser-generated, surfactant-free nanoparticles by continuous centrifugation
Authors: Kohsakowski Sebastian , Seiser Felix , Wiederrecht Jan-Philipp , Reichenberger Sven , Vinnay Thomas , Barcikowski Stephan , Marzun Galina
Published: November 2019

High-power, nanosecond, pulsed-laser ablation in liquids enables the continuous synthesis of highly pure colloidal nanoparticles (NPs) at an application-relevant scale. The gained mass-weighted particle size distribution is however often reported to be broad, requiring post treatment like centrifugation to remove undesired particle size fractions. To date, available centrifugation techniques are generally discontinuous, limiting the throughput and hindering economic upscaling. Hence, throughout this paper, a scalable, continuously operating centrifugation of laser-generated platinum NPs in a tubular bowl centrifuge is reported for the first time. To that end, using a 121 W ns-laser, the continuous production of a colloidal suspension of NPs, yet with broad particle size distribution has been employed, yielding productivities of 1–2 g h−1 for gold, silver, and platinum. The power-specific productivities (Au: 18 mg h−1 W−1, Pt: 13 mg h−1 W−1, Ag: 8 mg h−1 W−1, Ni: 6 mg h−1 W−1) are far higher than reported before. Subsequent downstream integration of a continuously operating tubular bowl centrifuge was successfully achieved for Pt NPs allowing the removal of undesired particle size with high throughput. By means of a systematic study of relevant centrifugation parameters involved, effective size optimization and respective size sharpness parameters for a maximum Pt NP diameter of 10 nm are reported. The results of the experimental centrifugation of laser-generated Pt NPs were in excellent agreement with the theoretically calculated cut-off diameter. After centrifugation with optimized parameters (residence time of 5 min; g-force of 38,454 g), the polydispersity indices of the Pt NPs size distributions were reduced by a factor of six, and high monodispersity was observed.
Summary of Research Status of Assembly Nodes
Authors: Xie Xinying , Wang Di , Qian Yongmei , Jin Yujie
Published: November 2019

Prefabricated building is a building in which prefabricated components are assembled at the construction site. There are many joints between the prefabricated components of the prefabricated building, so the assembled node connection becomes the key to the development of the prefabricated building. This paper summarizes the current research status of fabricated joints at home and abroad, analyzes the research status of joint connection and seismic performance of joints, and discusses the development prospect and prospect of fabricated buildings.
Analysis on Defense Safety Design of Building’s Outside Environment of Semi-gated Residential Community in Changchun in the Perspective of Weakening Fear of Victimization
Authors: Wang Keqi , Wang Jiayi , Xu Chao
Published: November 2019

The spatial environment is the carrier of urban crime. Improper spatial environment provides conditions and opportunities for urban crime, which is the main factor that triggers residents’ fear of victimization. With the aid of the “CPTED” and the “vulnerable to crime” theories, the author proposes that the spatial position, the spatial morphology and the spatial atmosphere are three physical properties of buildings’ outside environment that affect residents’ fear of victimization, after teasing out the environmental characters that influence residents’ fear of victimization, such as accessibility, visibility, identifiability, territoriality, positivity and imagery, etc. The author puts forwards some defense safety design strategies on weakening residents’ fear of victimization for a typical semi-gated residential community in Changchun.
Study on the mechanical property of precast reinforced concrete sandwich insulation walls
Authors: Liu Li , Hou Weikai , Tan Guanglin , Li Qingqing
Published: November 2019

In this paper, a finite element analysis model of a precast reinforced concrete sandwich insulation wall (PRCSIW) is established according to the out-of-plane static load test of the wall. With the consideration of the structural characteristics of PRCSIW, the influences of insulation layer thickness, insulation material type, fastening piece type and fastening piece distribution mode on the mechanical performance of the wall is analyzed. Our work gives a theoretical basis for the optimal design of precast sandwich insulation walls.
Structural elastoplastic time-history analysis using solid element
Authors: Chen Xiaoming , Sun Jianyun , Li Yungui
Published: November 2019

Beam element is often used for simulation of frames, and the two-dimensional element is used for simulation of shear walls and slabs in structural analysis. This kind of method can be used for most of the conventional structures, but for the super-large section of super-tall buildings or the complex geometry structural members, this simplified may produce significant numerical error. In this paper, three-dimensional solid element is used to simulate the special shape members in a framework, and the embedding of model processing, multipoint constraints and other special constraint forms are introduced, which provides a new idea for engineers to use three-dimensional solid element to simulate the building structures. The results of the example show that the simplification of the special members in the structure will not only have a significant impact on the local results of the structure, but also may cause analysis bias on the overall results of the structure.
A Study on Safety Awareness by Risk Avoidance in Building Facilities & Practicability of Risk Prediction Sheets under ISO45001
Authors: Wariishi Hiroyuki , Tanaka Takehiro
Published: November 2019

The study discussed in this paper aims to prevent hazards and risks which may occur during the installation of building facilities, by making the most of risk prediction training sheets (hereafter,risk prediction sheets) and analyzing the degree of safety awareness among trainees. This survey has been carried out for nearly five years, in which supervisors and workers who are engaged in equipment installation were tested with illustrated risk prediction sheets depicting typical equipment installation activities. And we suggested the practicability of risk prediction sheets under ISO45001.
Load-displacement Relationship Modeling with Power Function on Cylindrical Underreamed Ground Anchor
Authors: Guo Gang , Liu Zhong , Tang Aiping , Hu Xiaochen
Published: November 2019

An underreamed ground anchor technique is developed for high anchorage force demand based on shaft anchors worldwide. Engineers and scholars invented various types of underreamed ground anchors, such as those based on jet grouting, mechanical reaming, and blasting. To guarantee the quality of anchorage section and reduce cost, a new type of cylindrical underreamed ground anchor with geotextile bag was developed and applied throughout China. Through 33 Q–s curves in the field tests of underreamed anchor with geotextile bag, a power function model was established for describing the relationship between the load and displacement of a cylindrical underreamed anchor. Finally, the high precision of the function model was verified.