bluuebunny/crossref_metadata_2025 huggingface dataset:
Ralstonia solanacearum promotes pathogenicity by utilizing l‐glutamic acid from host plants
Authors: Shen Fangfang , Yin Wenfang , Song Shihao , Zhang Zhihan , Ye Peiyi , Zhang Yong , Zhou Jianuan , He Fei , Li Peng , Deng Yinyue
Published: June 2020

Ralstonia solanacearum is an important bacterial pathogen that can infect a broad range of plants worldwide. A previous study showed that R. solanacearum could respond to exogenous organic acids or amino acids to modulate cell motility. However, it was unclear whether R. solanacearum uses these compounds to control infection. In this study, we found that R. solanacearum GMI1000 uses host plant metabolites to enhance the biosynthesis of virulence factors. We demonstrated that l‐glutamic acid from host plants is the key active component associated with increased extracellular polysaccharide production, cellulase activity, swimming motility, and biofilm formation in R. solanacearum GMI1000. In addition, l‐glutamic acid also promoted colonization of R. solanacearum cells in the roots and stems of tomato plants and accelerated disease incidence. Furthermore, genetic screening and biochemical analysis suggested that RS01577, a hybrid sensor histidine kinase/response regulator, is involved in l‐glutamic acid signalling in R. solanacearum. Mutations in RS01577 and exogenous addition of l‐glutamic acid to the GMI1000 wild‐type strain had overlapping effects on both the transcriptome and biological functions of R. solanacearum, including on motility, biofilm formation, and virulence. Thus, our results have established a new interaction mechanism between R. solanacearum and host plants that highlights the complexity of the virulence regulation mechanism and may provide new insight into disease control.
Fazlur Rahman’s Influence on Contemporary Islamic Thought
Authors: Akbar Ali
Published: June 2020

This article examines the influence of Fazlur Rahman, one of the most widely quoted scholars among contemporary Muslim modernists, on contemporary Islamic thought. It explores how Rahman’s ideas about revelation and the interpretation of the Qurʾān have influenced some contemporary Muslim scholars of the late twentieth and early twenty‐first centuries, such as Abdolkarim Soroush, Arash Naraqi, Abdullah Saeed, Nurcholish Madjid, Farid Esack and Amina Wadud, and thus have given rise – whether directly or indirectly – to such schools of thought as Islamic liberation theology and feminist exegesis of the Qurʾān. The article also provides a critical evaluation the thought of Fazlur Rahman, and examines how its shortcomings have been rectified by his followers. The article ends with some recommendations to contextualist scholars about Qurʾānic justice and its relation with our contemporary understandings of justice.
Leaf traits can be used to predict rates of litter decomposition
Authors: Rosenfield Marc V. , Keller Jason K. , Clausen Catrina , Cyphers Kimberlee , Funk Jennifer L.
Published: June 2020

Strong relationships exist between litter chemistry traits and rates of litter decomposition. However, leaf traits are more commonly found in online trait databases than litter traits and fewer studies have examined how well leaf traits predict litter decomposition rates. Furthermore, while bulk leaf nitrogen (N) content is known to regulate litter decomposition, few studies have explored the importance of N biochemistry fractions, such as protein and amino acid concentration. Here, we decomposed green leaves and naturally senesced leaf litter of nine species representing a wide range of leaf functional traits. We evaluated the ability of traits associated with leaf and litter physiology, N biochemistry and carbon quality to predict litter decomposition. The objectives of this study were to determine if 1) N fractions explain variation in decomposition that is not explained by bulk N parameters alone and 2) green leaf traits, as opposed to litter traits, can accurately determine rates of litter decomposition. We found N biochemistry traits to have similar predictive power to that of bulk N. We also found that leaf N biochemistry traits correlated strongly with each other and aligned on a single axis of variation resembling that of the ‘leaf economic spectrum.’ We noted that green leaf traits associated with this axis, including bulk N, N fractions, leaf mass per area and lignin, were better predictors of decomposition than litter traits and concluded that leaf trait databases may be used to accurately predict litter decomposition. Future decomposition studies should consider fitting the more flexible Weibull distribution model to litter cohorts, as this model is much less rigid than the classic exponential decay model traditionally used in decomposition studies.
Primary determinants of communities in deadwood vary among taxa but are regionally consistent
Authors: Müller Jörg , Ulyshen Mike , Seibold Sebastian , Cadotte Marc , Chao Anne , Bässler Claus , Vogel Sebastian , Hagge Jonas , Weiß Ingmar , Baldrian Petr , Tláskal Vojtěch , Thorn Simon
Published: June 2020

The evolutionary split between gymnosperms and angiosperms has far‐reaching implications for the current communities colonizing trees. The inherent characteristics of dead wood include its role as a spatially scattered habitat of plant tissue, transient in time. Thus, local assemblages in deadwood forming a food web in a necrobiome should be affected not only by dispersal ability but also by host tree identity, the decay stage and local abiotic conditions. However, experiments simultaneously manipulating these potential community drivers in deadwood are lacking. To disentangle the importance of spatial distance and microclimate, as well as host identity and decay stage as drivers of local assemblages, we conducted two consecutive experiments, a 2‐tree species and 6‐tree species experiment with 80 and 72 tree logs, respectively, located in canopy openings and under closed canopies of a montane and a lowland forest. We sampled saproxylic beetles, spiders, fungi and bacterial assemblages from logs. Variation partitioning for community metrics based on a unified framework of Hill numbers showed consistent results for both studies: host identity was most important for sporocarp‐detected fungal assemblages, decay stage and host tree for DNA‐detected fungal assemblages, microclimate and decay stage for beetles and spiders and decay stage for bacteria. Spatial distance was of minor importance for most taxa but showed the strongest effects for arthropods. The contrasting patterns among the taxa highlight the need for multi‐taxon analyses in identifying the importance of abiotic and biotic drivers of community composition. Moreover, the consistent finding of microclimate as the primary driver for saproxylic beetles compared to host identity shows, for the first time that existing evolutionary host adaptions can be outcompeted by local climate conditions in deadwood.
Estimating canopy gross primary production by combining phloem stable isotopes with canopy and mesophyll conductances
Authors: Vernay Antoine , Tian Xianglin , Chi Jinshu , Linder Sune , Mäkelä Annikki , Oren Ram , Peichl Matthias , Stangl Zsofia R. , Tor‐Ngern Pantana , Marshall John D.
Published: June 2020

Gross primary production (GPP) is a key component of the forest carbon cycle. However, our knowledge of GPP at the stand scale remains uncertain, because estimates derived from eddy covariance (EC) rely on semi‐empirical modelling and the assumptions of the EC technique are sometimes not fully met. We propose using the sap flux/isotope method as an alternative way to estimate canopy GPP, termed GPPiso/SF, at the stand scale and at daily resolution. It is based on canopy conductance inferred from sap flux and intrinsic water‐use efficiency estimated from the stable carbon isotope composition of phloem contents. The GPPiso/SF estimate was further corrected for seasonal variations in photosynthetic capacity and mesophyll conductance. We compared our estimate of GPPiso/SF to the GPP derived from PRELES, a model parameterized with EC data. The comparisons were performed in a highly instrumented, boreal Scots pine forest in northern Sweden, including a nitrogen fertilized and a reference plot. The resulting annual and daily GPPiso/SF estimates agreed well with PRELES, in the fertilized plot and the reference plot. We discuss the GPPiso/SF method as an alternative which can be widely applied without terrain restrictions, where the assumptions of EC are not met.
Photogrammetric terminology: fourth edition
Authors: Granshaw Stuart I.
Published: June 2020

This contribution offers a considerably expanded and updated version of the previous three editions of this guide to terms used in the photogrammetric literature. The aim is to assist authors in preparing contributions for publication and readers in the wider geomatics community in understanding current photogrammetric and related terminology and abbreviations. The paper is recognised as an ISPRS document (https://www.isprs.org/documents/).
Geometric modelling and calibration of a spherical camera imaging system
Authors: Lichti Derek D. , Jarron David , Tredoux Wynand , Shahbazi Mozhdeh , Radovanovic Robert
Published: June 2020

The Ladybug5 is an integrated, multi‐camera system that features a near‐spherical field of view. It is commonly deployed on mobile mapping systems to collect imagery for 3D reality capture. This paper describes an approach for the geometric modelling and self‐calibration of this system. The collinearity equations of the pinhole camera model are augmented with five radial lens distortion terms to correct the severe barrel distortion. Weighted relative orientation stability constraints are added to the self‐calibrating bundle adjustment solution to enforce the angular and positional stability between the Ladybug5’s six cameras. Centimetre‐level 3D reconstruction accuracy can be achieved, with image‐space precision and object‐space accuracy improved by 92%and 93%, respectively, relative to a two‐term lens distortion model. Sub‐pixel interior orientation stability and millimetre‐level relative orientation stability were also demonstrated over a 10‐month period.
The effects of dispositional restrictiveness on physiological markers of challenge and threat during a hypothetical transitional period in romantic relationships
Authors: Tudder Ashley , Gresham Abriana M. , Peters Brett J. , Reis Harry T. , Jamieson Jeremy P.
Published: June 2020

Restrictiveness, a component of relationship dominance associated with monitoring and regulating partners' behavior, is a risk factor and accelerant of Intimate Partner Violence (IPV). Few studies, however, have examined in vivo physiological responses associated with restrictiveness. Toward this end, 105 romantic couples (N = 210) completed measures of restrictiveness and had their physiological responses recorded in anticipation of and during a dyadic interaction in which they discussed a hypothetical transitional period in which one person (thediscloser) revealed to their partner (theresponder) that they had just gotten into their dream school or was offered their dream job. Individuals high (vs. low) in restrictiveness exhibited physiological responses indicative of greater psychological challenge (e.g., elevated cardiac output and lower peripheral resistance) in anticipation of and during the conversation. In contrast, their partners exhibited greater physiological indicators of psychological threat in anticipation of (but not during) the conversation, particularly when assigned to the discloser role. Exploratory analyses of communication behaviors corroborated the physiological data. This research integrates the biopsychosocial model of challenge and threat with theories of relationship power and dominance to demonstrate the physiological manifestations of a well‐known risk factor for IPV in romantic relationships and interpersonal restrictiveness.
Aerobic swimming in intensive finfish aquaculture: applications for production, mitigation and selection
Authors: McKenzie David J. , Palstra Arjan P. , Planas Josep , MacKenzie Simon , Bégout Marie‐Laure , Thorarensen Helgi , Vandeputte Marc , Mes Daan , Rey Sonia , De Boeck Gudrun , Domenici Paolo , Skov Peter V.
Published: June 2020

We review knowledge on applications of sustained aerobic swimming as a tool to promote productivity and welfare of farmed fish species. There has been extensive interest in whether providing active species with a current to swim against can promote growth. The results are not conclusive but the studies have varied in species, life stage, swimming speed applied, feeding regime, stocking density and other factors. Therefore, much remains to be understood about mechanisms underlying findings of ‘swimming‐enhanced growth’, in particular to demonstrate that swimming can improve feed conversion ratio and dietary protein retention under true aquaculture conditions. There has also been research into whether swimming can alleviate chronic stress, once again on a range of species and life stages. The evidence is mixed but swimming does improve recovery from acute stresses such as handling or confinement. Research into issues such as whether swimming can improve immune function and promote cognitive function is still at an early stage and should be encouraged. There is promising evidence that swimming can inhibit precocious sexual maturation in some species, so studies should be broadened to other species where precocious maturation is a problem. Swimming performance is a heritable trait and may prove a useful selection tool, especially if it is related to overall robustness. More research is required to better understand the advantages that swimming may provide to the fish farmer, in terms of production, mitigation and selection.
Nursing professional practice environment and its relationship with nursing outcomes in intensive care units: a test of the structural equation model
Authors: Rivaz Mozhgan , Tavakolinia Mahboobeh , Momennasab Marzieh
Published: June 2020

Introduction

Burnout, intention to leave and ultimately shortage of skilled nurses are associated with poor practice environments; however, in Iran comprehensive data are unavailable. The aim of this study was to investigate the relationships between the nursing professional practice environment with nurses’ burnout and intention to leave in intensive care units, using structural equation modelling analysis.

Methods

This cross‐sectional, multi‐centred study was conducted among 320 nurses in twenty ICUs of five teaching hospitals affiliated with Shiraz University of Medical Sciences from September 2018 to June 2019. Valid measurement instruments including Nursing Professional Practice Environment Questionnaire (NPPEQ), Maslach Burnout Inventory (MBI) and Anticipated Turnover Scale (ATS) were used for data collection.

Results

Goodness‐of‐fit statistics confirmed a model with burnout dimensions in mediating positions between nursing professional practice environment dimensions and intention to leave, explaining 86.4% of the variation.

Conclusion

The results confirmed a theoretical model with structural the relationships among the nursing professional practice environment, burnout and intention to leave in nurses working in ICUs. In this model, burnout had a strong direct positive effect on intention to leave. The results can provide guidance for various stakeholders, such as health policymakers and nurse managers attempting to improve the quality of nurses’ workplace, by drawing their attention to various factors influencing the retention of technically trained nurses in the critical care units.
Bedforms and sedimentary structures related to supercritical flows in glacigenic settings
Authors: Lang Jörg , Le Heron Daniel P. , Van den Berg Jan H. , Winsemann Jutta
Published: June 2020

Upper‐flow‐regime bedforms, including upper‐stage‐plane beds, antidunes, chutes‐and‐pools and cyclic steps, are ubiquitous in glacigenic depositional environments characterized by abundant meltwater discharge and sediment supply. In this study, the depositional record of Froude near‐critical and supercritical flows in glacigenic settings is reviewed, and similarities and differences between different depositional environments are discussed. Upper‐flow‐regime bedforms may occur in subglacial, subaerial and subaqueous environments, recording deposition by free‐surface flows and submerged density flows. Although individual bedform types are generally not indicative of any specific depositional environment, some observed trends are similar to those documented in non‐glacigenic settings. Important parameters for bedform evolution that differ between depositional environments include flow confinement, bed slope, aggradation rate and grain size. Cyclic‐step deposits are more common in confined settings, like channels or incised valleys, or steep slopes of coarse‐grained deltas. Antidune deposits prevail in unconfined settings and on more gentle slopes, like glacifluvial fans, sand‐rich delta slopes or subaqueous (ice‐contact) fans. At low aggradation rates, only the basal portions of bedforms are preserved, such as scour fills related to the hydraulic‐jump zone of cyclic steps or antidune‐wave breaking, which are common in glacifluvial systems and during glacial lake‐outburst floods and (related) lake‐level falls. Higher aggradation rates result in increased preservation potential, possibly leading to the preservation of complete bedforms. Such conditions are met in sediment‐laden jökulhlaups and subaqueous proglacial environments characterized by expanding density flows. Coarser‐grained sediment leads to steeper bedform profiles and highly scoured facies architectures, while finer‐grained deposits display less steep bedform architectures. Such differences are in part related to stronger flows, faster settling of coarse clasts, and more rapid breaking of antidune waves or hydraulic‐jump formation over hydraulically rough beds.
Clinical characteristics and pathological depths of syringomas in 94 Korean patients
Authors: Lim Youngkyoung , Lee Jongeun , Jang Donghwi , Abudureyimu Gulimila , Lee Jong‐Hee
Published: June 2020

Background

Syringoma is a common benign tumor with eccrine origin that typically occurs on the face of middle‐aged women. Laser ablation with CO2 laser or Er:YAG laser has been widely used in the clinical field, often leading to scars due to its deep location. This study aimed to investigate clinical characteristics and pathological depths of the lesions in syringoma patients.

Materials and methods

Syringoma patients, pathologically confirmed at Samsung medical center (Seoul, Korea) from January 1996 to March 2019, were analyzed. Clinical characteristics such as the location of lesion, age, and sex, and pathological depths of the lesions were investigated, and univariable and multivariable analyses were done for these factors.

Results

Of total 94 syringomas, 17.0% were located on periocular area, 10.6% on forehead, 34.0% on head and neck areas excluding periocular area and forehead, and 38.3% on trunk and extremities. The mean depth of syringoma from the surface including stratum corneum to the deepest stromal location was 1174.14 ± 1142.95 μm for periocular area, 1055.93 ± 247.76 μm for forehead, 1488.06 ± 1217.36 μm for other areas of head and neck including scalp, and 1169.53 ± 349.2 for the lesions located at trunk and extremities including external genitalia. No significant correlation was observed from univariable analysis and multivariable analysis by age, sex, and site of lesion.

Conclusion

Our findings offer valuable information of the mean depth of syringoma at different sites, which can be taken into consideration for successful treatment without adverse events such as scarring.
Effect of impact velocity and impact angle on residual stress fields caused by foreign object damage
Authors: Matsunaga Hisao
Published: June 2020

In order to study the residual stress induced by foreign object damage (FOD), the distribution of residual stress caused by the impact of a hard spherical body was measured via the sin2ψ technique, using synchrotron X‐ray. A steel sphere was impacted onto a flat surface of a Ti‐6Al‐4V alloy from an angle of either 90° or 45°, at a velocity of 180 m/s. The same sphere was also quasi‐statically pressed into the surface. In the cases of right‐angled impact and quasi‐static indentation, a compressive residual stress was extensively distributed inside the generated crater. No remarkable difference in residual stress distribution was noted between the dynamic case and the quasi‐static case. However, at an impact angle of 45°, a tensile residual stress that is more detrimental to fatigue strength was widely distributed inside the crater. Outside of the craters, tensile stress was generally observed in all cases.
Machine learning–based prediction of transfusion
Authors: Mitterecker Andreas , Hofmann Axel , Trentino Kevin M. , Lloyd Adam , Leahy Michael F. , Schwarzbauer Karin , Tschoellitsch Thomas , Böck Carl , Hochreiter Sepp , Meier Jens
Published: June 2020

Background

The ability to predict transfusions arising during hospital admission might enable economized blood supply management and might furthermore increase patient safety by ensuring a sufficient stock of red blood cells (RBCs) for a specific patient. We therefore investigated the precision of four different machine learning–based prediction algorithms to predict transfusion, massive transfusion, and the number of transfusions in patients admitted to a hospital.

Study Design and Methods

This was a retrospective, observational study in three adult tertiary care hospitals in Western Australia between January 2008 and June 2017. Primary outcome measures for the classification tasks were the area under the curve for the receiver operating characteristics curve, the F1 score, and the average precision of the four machine learning algorithms used: neural networks (NNs), logistic regression (LR), random forests (RFs), and gradient boosting (GB) trees.

Results

Using our four predictive models, transfusion of at least 1 unit of RBCs could be predicted rather accurately (sensitivity for NN, LR, RF, and GB: 0.898, 0.894, 0.584, and 0.872, respectively; specificity: 0.958, 0.966, 0.964, 0.965). Using the four methods for prediction of massive transfusion was less successful (sensitivity for NN, LR, RF, and GB: 0.780, 0.721, 0.002, and 0.797, respectively; specificity: 0.994, 0.995, 0.993, 0.995). As a consequence, prediction of the total number of packed RBCs transfused was also rather inaccurate.

Conclusion

This study demonstrates that the necessity for intrahospital transfusion can be forecasted reliably, however the amount of RBC units transfused during a hospital stay is more difficult to predict.
How Much Is Your Strangle Worth? On the Relative Value of the Strangle under the Black-Scholes Pricing Model
Authors: Boukai Ben
Published: June 2020

Trading option strangles is a highly popular strategy often used by market participants to mitigate volatility risks in their portfolios. We propose a measure of the relative value of a delta-Symmetric Strangle and compute it under the standard Black-Scholes-Merton option pricing model. This new measure accounts for the price of the strangle, relative to the Present Value of the spread between the two strikes, all expressed, after a natural re-parameterization, in terms of delta and a volatility parameter. We show that under the standard BSM model, this measure of relative value is bounded by a simple function of delta only and is independent of the time to expiry, the price of the underlying security or the prevailing volatility used in the pricing model. We demonstrate how this bound can be used as a quick benchmark to assess, regardless the market volatility, the duration of the contract or the price of the underlying security, the market (relative) value of the strangle in comparison to its BSM (relative) price. In fact, the explicit and simple expression for this measure and bound allows us to also study in detail the strangle’s exit strategy and the corresponding optimal choice for a value of delta.
Effect of Blade Trailing Edge Cutting Angle on Unstable Flow and Vibration in a Centrifugal Pump
Authors: Cui Baoling , Li Wenqing , Zhang Chenliang
Published: June 2020

The vibration induced by the unsteady fluid exciting force in a centrifugal pump is one of the important factors affecting the reliable operation of the pump. In this study, the cutting of the blade trailing edge of a straight blade is presented to improve the unstable flow and vibration in a centrifugal pump. Based on the large eddy simulation (LES) and fluid–solid coupling method, the transient pressure pulsation, unstable flow structure, and vibration displacement of a centrifugal pump were investigated with different cutting angles of the trailing edge under the design flow rate. The external characteristics of the centrifugal pumps were calculated and compared using the shear stress transport (SST) k–ω turbulence model. The results show that the heads and efficiencies of the pumps with 30 deg and 45 deg cutting angles of the trailing edge slightly improved. The pressure pulsation on the volute evaluated by dominant frequency–amplitude and pressure pulsation energy was reduced due to the lesser average vorticity intensity and trailing vortex area in the centrifugal pump. Therefore, the vibration displacement and the vibration energy at the low frequency of the impeller decreased.
Comparative Study on Power Module Architectures for Modularity and Scalability
Authors: Lu Mei-Chien
Published: June 2020

Silicon carbide (SiC) wide bandgap power electronics are being applied in hybrid electric vehicle (HEV) and electrical vehicles (EV). The Department of Energy (DOE) has set target performance goals for 2025 to promote EV and HEV as a means of carbon emission reduction and long-term sustainability. Challenges include higher expectations on power density, performance, efficiency, thermal management, compactness, cost, and reliability. This study will benchmark state of the art silicon and SiC technologies. Power modules used in commercial traction inverters are analyzed for their within-package first-level interconnect methods, module architecture, and integration with cooling structure. A few power module package architectures from both industry-adopted standards and proposed patented technologies are compared in modularity and scalability for integration into inverters. The current trends of power module architectures and their integration into inverter are also discussed. The development of an eco-system to support the wide bandgap semiconductors-based power electronics is highlighted as an ongoing challenge.
Generation Mechanism and Quality of Milling Surface Profile for Variable Pitch Tools Considering Runout
Authors: Niu Jinbo , Jia Jinjie , Sun Yuwen , Guo Dongming
Published: June 2020

Surface profile is one of the foremost aspects to evaluate milling performance. Its generation mechanism is affected by a variety of factors such as tool geometry, runout values, and process parameters and thus still deserves further investigation. This paper aims to propose a unified method to study the surface generation mechanism and to predict the machining quality for variable pitch tools considering runout. First, a Floquet theory based algorithm is extended to analyze the machining stability and output the dynamic responses of the machining system. The resultant trajectories of cutting edges are obtained by kinematic synthesis of system vibrations, tool rotations, and machining feed. Next, both the surface location error (SLE) and the surface roughness are simultaneously extracted from the edge trajectories. A series of cutting tests are performed to validate the prediction results. Some new characteristics of the machined surface profile in terms of form errors and teeth marks are discovered and theoretically explained. Finally, the joint influences of tool geometry, runout values, and process parameters on the surface generation mechanism and quality are analyzed in detail with the proposed method.
Thermal Optimization of Air Foil Thrust Bearings Using Different Foil Materials
Authors: Rieken Markus , Mahner Marcel , Schweizer Bernhard
Published: June 2020

Air foil bearings are used in turbomachinery applications with high speeds and in oil-free environments. Their numerical analysis has to account for the multiphysicality of the problem. This work features a detailed thermo-elasto-hydrodynamic model of an air foil thrust bearing with bump-type foil-structure. The bearing geometry is designed to produce a high load capacity while maintaining thermally stable conditions. The presented model considers foil deformations using a Reissner–Mindlin-type shell theory. Dry friction (stick-slip approach) between the top foil, the bump foil, and the base plate is taken into account in the model. Reynolds equation from the lubrication theory is used to study the hydrodynamic behavior of the air film. A thermal model of the lubricating gap, the foil sandwich, and the rotor disk including heat fluxes into the rotor and the periphery as well as a cooling flow on the backside of the rotor disk are presented. Elastic deformations of the rotor disk due to centrifugal effects are calculated; deformations caused by temperature gradients are investigated as well. In air foil thrust bearings, very high temperatures are often observed and a forced cooling flow through the foil sandwich has to be applied. Using a cooling flow by applying a pressure difference between the inner and outer radius of the thrust bearing has several drawbacks: the additional cooling flow reduces the overall efficiency of the machine and requires additional constructive measures. In this work, a passive cooling concept is analyzed, where the typical steel foils are replaced with other materials, which have a significantly higher thermal conductivity. The simulation results show that the bearing temperatures can be reduced markedly (up to 70 °C in the considered test case) by this approach.
The Effect of an Upstream Dune-Shaped Shells on Forward and Backward Injection Hole Film Cooling
Authors: Ben Ali Kouchih Fatima , Boualem Khadidja , Grine Mustapha , Azzi Abbes
Published: June 2020

This article presents the numerical results of a new film cooling design that combines the backward injection hole with Barchan-dune-shaped shells (BH-BDS).The performance of this novel design in improving the film cooling effectiveness is compared to other configurations, forward injection hole (FH), backward injection hole (BH), and the configuration that combines the forward injection with Barchan-dune-shaped shells (FH-BDS). Three blowing ratios are considered in this article, M = 0.5, 1.0, and 1.5. The air coolant was injected through holes inclined at 35 and 155 deg for forward and backward cases, respectively. The lateral-averaged film cooling effectiveness and the distribution of adiabatic film cooling efficiency are studied using commercial software ansys-cfx. Three turbulence models, including the k–ω shear stress transport model, standard k–ε, and renormalization group theory (RNG) k–ε are examined in this investigation. The RNG k–ε model is adopted for the present simulation. The main result of this study reveals that the presence of upstream dune-shaped shells with backward hole yield a better film cooling effectiveness especially at higher blowing ratios (M ≥ 1). At M = 1.5, the FH-BDS and BH-BS cases provide an improvement in the area weighted average film cooling approximately about 24.79% and 10.56%, respectively. The BH-BDS design reduces the pressure loss as compared to BH.
Formation, Characterization, and Wear Behavior of Aluminide Coating on Mirrax® ESR Steel by Low-Temperature Aluminizing Process
Authors: Yener Tuba , Erdogan Azmi , Gök Mustafa Sabri , Zeytin Sakin
Published: June 2020

The aim of this study was to investigate the effect of low-temperature aluminizing process on the microstructure and dry sliding wear properties of Mirrax steel. Low-temperature aluminizing process was applied on Mirrax steel at 600, 650, and 700 °C for 2, 4, and 6 h. The packs for the process were prepared using pure aluminum powder as aluminum deposition source. Ammonium chloride NH4Cl and Seydisehir Al2O3 powder were used as the activator and the inert filler, respectively. Scanning electron microscope (SEM)/energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD) analysis were applied for characterization of the coating surfaces. The through-thickness variation in the layer microstructure was determined and it was found to vary between 1 µm and 45 µm which increased with higher process temperature and time. After the deposition process, the coating layer hardness increased to 1000 HVN, whereas the hardness of the matrix was 250 HVN. The wear tests were performed using a ball-on-disc tribometer under 5 N load at room temperature and 500 °C on aluminized and untreated Mirrax steel. In both room temperature and high-temperature wear tests, it was determined that the aluminizing process increased the wear resistance of Mirrax steel. Increasing aluminizing time and temperature also increased the wear resistance. The uncoated and thin-coated samples generally exhibited wear in the form of plastic deformation and adhesion related ruptures. A high degree of tribological layer was observed on the wear trace on samples with high coating thickness, especially in high-temperature tests. Therefore, the volume losses in these samples were induced by fatigue crack formation and delamination.
X-ray photoelectron spectroscopy: A perspective on quantitation accuracy for composition analysis of homogeneous materials
Authors: Brundle Christopher Richard , Crist Bruce Vincent
Published: June 2020

We present a perspective on the use of XPS relative peak intensities for determining composition in homogeneous bulk materials. Nonhomogenous effects, such as composition variation with depth or severe topography effects (e.g., in nanoparticles), are not discussed. We consider only the use of conventional laboratory-based instruments with x-ray sources, Alkα or Mgkα. We address accuracy (not precision, which is much more straightforward) using relative sensitivity factors, RSFs, obtained either empirically from standards (e-RSF) or from the use of theoretical cross sections, σ, (t-RSF). Issues involved are (1) the uncertainty of background subtraction of inelastically scattered electrons, (2) the accuracy of the RSFs, and (3) the role of XPS peak satellite structure, which affects both (1) and (2) above. The XPS of materials tends to fall into two broad classes: where the signals being used for quantification are “main” peaks, which are narrower and more symmetric, followed by a relatively low background with only weak satellite structure and where the “main” peaks are broader and often asymmetric, followed by backgrounds that are higher and have a stronger satellite structure. The former generally will yield better accuracy, more easily, than the latter. The latter comprises all compounds containing elements with open valence shell electrons. These are mostly the 3d, 4d, and 5d transition metals, the lanthanides, and the actinides. Compounds involving only the first row elements, Li to F, where the 1s binding energy is used for quantitation, are those where the best accuracy is potentially achievable. We specifically address the issue of long-claimed serious discrepancies between e-RSFs and t-RSFs, which were interpreted as indicating calculated σs, used as a parameter in t-RSFs, were seriously in error. We conclude this claim to be untrue and that, if done correctly, there is no disagreement between the two approaches within the limits of accuracy claimed. Finally, we suggest protocols for rapid element composition analysis by obtaining relative XPS signal intensities using only low energy resolution.
In situ surface analysis of an ion-energy-dependent chlorination layer on GaN during cyclic etching using Ar+ ions and Cl radicals
Authors: Hasegawa Masaki , Tsutsumi Takayoshi , Tanide Atsushi , Nakamura Shohei , Kondo Hiroki , Ishikawa Kenji , Sekine Makoto , Hori Masaru
Published: June 2020

Gallium nitride (GaN) semiconductor devices must be fabricated using plasma etching with precise control of the etching depths and minimal plasma-induced damage on the atomic scale. A cyclic process comprising etchant adsorption and product removal may be suitable for this purpose but an understanding of the associated etching surface reactions is required. The present work examined the formation of a chlorinated layer based on Cl radical adsorption on a GaN surface in conjunction with Ar ion irradiation. This research employed beam experiments and in situ x-ray photoelectron spectroscopy. The results show that N atoms are preferentially desorbed during exposure to Ar ions to produce Ga-rich layers at depths of 0.8 and 1.1 nm at an Ar ion dosage on the order of 1016 cm−2 and ion energies of 116.0 and 212.6 eV, respectively. Subsequent exposure of the irradiated Ga-rich layer to Cl radicals removes some Ga atoms and produces a chlorinated layer over the GaN surface. This chlorinated layer has a thickness on the order of 1 nm following Cl radical dosages on the order of 1019 cm−2. This study of plasma-treated surfaces is expected to assist in developing means of controlling the etching depth during the atomic layer etching of GaN via Ar ion bombardment.
Procedure which allows the performance and calibration of an XPS instrument to be checked rapidly and frequently
Authors: Wolstenholme John
Published: June 2020

The performance and calibration of an XPS instrument can change with time. Changes may be gradual so that users may not notice them from day to day unless they actively compare the current performance of the instrument with its recently optimized performance. This publication describes a method by which such a comparison may be made very rapidly. A tool, based on a Microsoft Excel workbook, has been made available to assist in the comparison and to highlight aspects of an instrument's performance which might have changed significantly. The whole procedure is rapid, minimizing the impact on both instrument availability and user time. This means that it may be followed frequently without significantly affecting laboratory throughput.
A breathable, biodegradable, antibacterial, and self-powered electronic skin based on all-nanofiber triboelectric nanogenerators
Authors: Peng Xiao , Dong Kai , Ye Cuiying , Jiang Yang , Zhai Siyuan , Cheng Renwei , Liu Di , Gao Xiaoping , Wang Jie , Wang Zhong Lin
Published: June 2020

A breathable, biodegradable, antibacterial, and self-powered skin is developed.
Formalizing land rights can reduce forest loss: Experimental evidence from Benin
Authors: Wren-Lewis Liam , Becerra-Valbuena Luis , Houngbedji Kenneth
Published: June 2020

Registration of landholdings and land rights helped improve communal land management and reduced tree cover loss in Benin.
HIV-1 Integrase Inhibitors That Are Active against Drug-Resistant Integrase Mutants
Authors: Smith Steven J. , Zhao Xue Zhi , Passos Dario Oliveira , Lyumkis Dmitry , Burke Terrence R. , Hughes Stephen H.
Published: June 2020

The currently recommended first-line therapy for HIV-1-infected patients is an integrase (IN) strand transfer inhibitor (INSTI), either dolutegravir (DTG) or bictegravir (BIC), in combination with two nucleoside reverse transcriptase inhibitors (NRTIs). Both DTG and BIC potently inhibit most INSTI-resistant IN mutants selected by the INSTIs raltegravir (RAL) and elvitegravir (EVG). BIC has not been reported to select for resistance in treatment-naive patients, and DTG has selected for a small number of resistant viruses in treatment-naive patients.
Validating the Use of Bovine Buccal Sampling as a Proxy for the Rumen Microbiota by Using a Time Course and Random Forest Classification Approach
Authors: Young Juliana , Skarlupka Joseph H. , Cox Madison S. , Resende Rafael Tassinari , Fischer Amelie , Kalscheur Kenneth F. , McClure Jennifer C. , Cole John B. , Suen Garret , Bickhart Derek M.
Published: June 2020

The gastrointestinal tracts of ruminants harbor a diverse microbial community that coevolved symbiotically with the host, influencing its nutrition, health, and performance. While the influence of environmental factors on rumen microbes is well documented, the process by which host genetics influences the establishment and colonization of the rumen microbiota still needs to be elucidated. This knowledge gap is due largely to our inability to easily sample the rumen microbiota. There are three common methods for rumen sampling but all of them present at least one disadvantage, including animal welfare, sample quality, labor, and scalability. The development and validation of noninvasive methods, such as buccal swabbing, for large-scale rumen sampling is needed to support studies that require large sample sizes to generate reliable results. The validation of buccal swabbing will also support the development of molecular tools for the early diagnosis of metabolic disorders associated with microbial changes in large herds.
The Conjugation Window in an Escherichia coli K-12 Strain with an IncFII Plasmid
Authors: Headd Brendan , Bradford Scott A.
Published: June 2020

There has been growing interest in horizontal gene transfer of antibiotic resistance plasmids as the antibiotic resistance crisis has worsened over the years. Most studies examining conjugation of bacterial plasmids focus on growing cultures of bacteria for short periods, but in the environment, most bacteria grow episodically and at much lower rates than in the laboratory. We examined conjugation of an IncFII antibiotic resistance plasmid in
E. coli
under growing and nongrowing conditions to understand the dynamics of conjugation under which the plasmid is transferred. We found that conjugation occurs in a narrow time frame when
E. coli
is transitioning from a growing to nongrowing phase and that the conjugation plateau develops because of a lack of capable donor cells in growing cultures. From an environmental aspect, our results suggest that episodic growth in nutrient-depleted environments could result in more conjugation than sustained growth in a nutrient rich environment.
A Novel Mobilizing Tool Based on the Conjugative Transfer System of the IncM Plasmid pCTX-M3
Authors: Dmowski Michał , Kern-Zdanowicz Izabela
Published: June 2020

The conjugation of donor and recipient bacterial cells resulting in conjugative transfer of mobilizable plasmids is the preferred method enabling the introduction of DNA into strains for which other transfer methods are difficult to establish (e.g., clinical strains). We have constructed
E. coli
strains carrying the conjugation system of the IncM plasmid pCTX-M3 integrated into the chromosome. To increase the mobilization efficiency up to 1,000-fold, two putative regulators of this system,
orf35
and
orf36
, were disabled. The constructed strains broaden the repertoire of tools for the introduction of DNA into the Gram-negative
Alpha
-,
Beta
-, and
Gammaproteobacteria
, as well as into Gram-positive bacteria such as
Bacillus subtilis
and
Lactococcus lactis
. The antibacterial procedure based on conjugation with the use of the
orf35
- and
orf36
-deficient strain lowered the recipient cell number by over 90% owing to the mobilizable plasmid-encoded toxin.
Limited Cross-Protection Provided by Prior Infection Contributes to High Prevalence of Influenza D Viruses in Cattle
Authors: Wan Xiu-Feng , Ferguson Lucas , Oliva Justine , Rubrum Adam , Eckard Laura , Zhang Xiaojian , Woolums Amelia R. , Lion Adrien , Meyer Gilles , Murakami Shin , Ma Wenjun , Horimoto Taisuke , Webby Richard , Ducatez Mariette F. , Epperson William
Published: June 2020

Influenza D viruses (IDVs) are panzootic in multiple animal hosts, but the underlying mechanism is unclear. Through multiple years of surveillance in the same order-buyer cattle facility, 32 IDV isolates were recovered from both healthy and sick animals, including those with evident antibodies against IDV. Active reassortment occurred in the cattle within this facility and in those across other areas, and multiple reassortants cocirculated in animals. These isolates are shown with a large extent of phenotypic diversity in replication efficiency and pathogenesis but little in antigenic properties. Animal experiments demonstrated that existing antibodies could not protect cattle from experimental reinfection with IDV. This study suggests that, in addition to epidemiological factors, limited protection from preexisting immunity against IDVs in cattle herds and cocirculation of a diverse viral genetic pool likely facilitate the high prevalence of IDVs in animal populations.
Genetically and Antigenically Divergent Influenza A(H9N2) Viruses Exhibit Differential Replication and Transmission Phenotypes in Mammalian Models
Authors: Belser Jessica A. , Sun Xiangjie , Brock Nicole , Pappas Claudia , Pulit-Penaloza Joanna A. , Zeng Hui , Jang Yunho , Jones Joyce , Carney Paul J. , Chang Jessie , Long Nguyen Van , Diep Nguyen Thi , Thor Sharmi , Di Han , Yang Genyan , Cook Peter W. , Creager Hannah M. , Wang Dayan , McFarland Jeffrey , Dong Pham Van , Wentworth David E. , Tumpey Terrence M. , Barnes John R. , Stevens James , Davis C. Todd , Maines Taronna R.
Published: June 2020

A(H9N2) influenza viruses are widespread in poultry in many parts of the world and for over 20 years have sporadically jumped species barriers to cause human infection. As these viruses continue to diversify genetically and antigenically, it is critical to closely monitor viruses responsible for human infections, to ascertain if A(H9N2) viruses are acquiring properties that make them better suited to infect and spread among humans. In this study, we describe an active poultry surveillance system established in Vietnam to identify the scope of influenza viruses present in live bird markets and the threat they pose to human health. Assessment of a recent A(H9N2) virus isolated from an individual in China in 2018 is also reported, and it was found to exhibit properties of adaptation to humans and, importantly, it shows similarities to strains isolated from the live bird markets of Vietnam.
The Complicated and Confusing Ecology ofMicrocystisBlooms
Authors: Wilhelm Steven W. , Bullerjahn George S. , McKay R. Michael L.
Published: June 2020

Blooms of the toxin-producing cyanobacteriumMicrocystisare increasing globally, leading to the loss of ecosystem services, threats to human health, as well as the deaths of pets and husbandry animals. While nutrient availability is a well-known driver of algal biomass, the factors controlling “who” is present in fresh waters are more complicated.Microcystispossesses multiple strategies to adapt to temperature, light, changes in nutrient chemistry, herbivory, and parasitism that provide a selective advantage over its competitors.
Characterizing the Mechanism of Action of an Ancient Antimicrobial, Manuka Honey, against Pseudomonas aeruginosa Using Modern Transcriptomics
Authors: Bouzo Daniel , Cokcetin Nural N. , Li Liping , Ballerin Giulia , Bottomley Amy L. , Lazenby James , Whitchurch Cynthia B. , Paulsen Ian T. , Hassan Karl A. , Harry Elizabeth J.
Published: June 2020

The threat of antimicrobial resistance to human health has prompted interest in complex, natural products with antimicrobial activity. Honey has been an effective topical wound treatment throughout history, predominantly due to its broad-spectrum antimicrobial activity. Unlike traditional antibiotics, honey-resistant bacteria have not been reported; however, honey remains underutilized in the clinic in part due to a lack of understanding of its mechanism of action. Here, we demonstrate that honey affects multiple processes in bacteria, and this is not explained by its major antibacterial components. Honey also uniquely affects bacterial membranes, and this can be exploited for combination therapy with antibiotics that are otherwise ineffective on their own. We argue that honey should be included as part of the current array of wound treatments due to its effective antibacterial activity that does not promote resistance in bacteria.