bluuebunny/crossref_metadata_2025 huggingface dataset:
The Growth of CuGaTe2 Thin Films by Two‐Step Closed Space Sublimation
Authors: Uruno Aya , Kobayashi Masakazu
Published: May 2019

CuGaTe2 layers are successfully grown on Si (001) and Mo/quartz substrates using two‐step closed space sublimation (CSS). The surface morphology of the Cu2Te first layer is affected by the surface free energy of the different substrates. Cu2Te grown on Si (001) comprises hexagonal islands which are highly oriented to the (0001). Conversely, Cu2Te layers formed on Mo/quartz substrates forms a thin film. The surface morphology and the quality of the crystals in the CuGaTe2 layers are investigated. Overgrowth by CuGaTe2 of the Cu2Te islands on Si substrates is confined to the islands only and there is no nucleation on the bare substrate. On the contrary, overgrowth by CuGaTe2 on the continuous Cu2Te films on Mo/quartz substrates produces continuous thin films. Therefore, the surface morphology of the CuGaTe2 layers can be controlled by changing the substrate material because they have different surface free energies.
Thermodynamic Properties of Wx(TaTiVCr)1−x High‐Entropy(‐Like) Alloy and Influence of Tungsten Content
Authors: Yao Xiao‐Jing , Ma Li , Jiang Shan , Luo Dong‐Ming , Gan Guo‐Yong , Wang Wei , Tang Bi‐Yu
Published: May 2019

Based on quasi‐harmonic Debye–Grüneisen model and thermal equation of state, thermodynamic properties of high‐entropy(‐like) alloy Wx(TaTiVCr)1−x (x = 0.30–0.67) phases have been studied by first principles density functional theory calculations combined with special quasi‐random structure (SQS) model, and the influence of W content is predominantly emphasized. Present investigations show that bulk modulus B of Wx(TaTiVCr)1−x declines with increasing temperature, and the softening tendency is similar for various W content, although the strength of Wx(TaTiVCr)1−x demonstrates overall lowering with simultaneous alloying of Ta, Ti, V, and Cr. The thermal expansion coefficient of Wx(TaTiVCr)1−x rises nonlinearly with increasing temperature, and the increase rate is lowered with more W content. The temperature dependence of heat capacity at constant volume CV and constant pressure CP of Wx(TaTiVCr)1−x also exhibits analog behavior at various W content. Thermodynamic entropy of Wx(TaTiVCr)1−x increases dramatically with temperature, and the contribution from electronic entropy, configuration, and vibrational entropy is discussed in detail. In addition, the Debye‐temperature and Grüneisen parameter are also analyzed. The present results are very valuable for optimizing the composition and comprehensive properties of W‐containing high‐entropy(‐like) alloys.
Temperature Dependence of Raman Spectra in Cu2FeSnS4 Magnetic Semiconductor Compound
Authors: Rincón Carlos , Quintero Eugenio , Quintero Miguel , Moreno Ekadink , Power Chrystian , Morocoima Manuel , Delgado Gerzon E.
Published: May 2019

The temperature dependence of the Raman scattering by phonons performed in bulk polycrystalline Cu2FeSnS4, that crystallizes with tetragonal symmetry in space group P, was measured between 10 and 300 K. The most important decay channel involves the three‐phonon process with two phonons of the same branch, including combinations of optical phonons with equal or different frequencies. Additionally, coupling of an optical mode to two phonons of different branches is observed. The strong A‐symmetry mode at 325 cm−1 decays into two optical phonons of the same frequencies 1 = 2 ≈ 162 cm−1. To explain the change of Raman shift with temperature it is necessary to take into account the contribution of thermal expansion contribution. We have observed a soft mode in the Raman spectra which accounts for the antiferromagnetic phase transition that happens in this material at a Néel temperature of about 40 K. The full width at half maximum of this A‐symmetry mode, extrapolated to zero temperature, is of about 2.6 cm−1, when the contribution of intrinsic defect scattering, which is of about 3. cm−1, is included in the calculation.
Efficient nonlinear data assimilation using synchronization in a particle filter
Authors: Pinheiro Flavia R. , van Leeuwen Peter J. , Geppert Gernot
Published: May 2019

Current data assimilation methods still face problems in strongly nonlinear cases. A promising solution is a particle filter, which provides a representation of the state probability density function (pdf) by a discrete set of particles. To allow a particle filter to work in high‐dimensional systems, the proposal density freedom is explored. We used a proposal density from synchronization theory, in which one tries to synchronize the model with the true evolution of a system using one‐way coupling, via the observations. This is done by adding an extra term to the model equations which will control the growth of instabilities transversal to the synchronization manifold. In this paper, an efficient ensemble‐based synchronization scheme is used as a proposal density in the implicit equal‐weights particle filter, a particle filter that avoids filter degeneracy by construction. Tests using the Lorenz96 model for a 1,000‐dimensional system show successful results, where particles efficiently follow the truth, both for observed and unobserved variables. These first tests show that the new method is comparable to, and slightly outperforms, a well‐tuned Local Ensemble Transform Kalman Filter. This methodology is a promising solution for high‐dimensional nonlinear problems in the geosciences, such as numerical weather prediction.
Research on reliability allocation technology for NC machine tool meta‐action
Authors: Li Yulong , Zhang Genbao , Wang Yongqin , Zhang Xiaogang , Ran Yan
Published: May 2019

The reliability of machine tool is getting more and more attention. Reasonable reliability allocation is beneficial to improve the inherent reliability of machine tool. However, the existing reliability allocation methods for machine tool have some limitations. For example, static part is selected as the reliability allocation object of machine tool, which cannot reflect the characteristics “function realized by motion”; factors affecting reliability allocation are not considered comprehensively, weights of experts are treated as the same, and the allocation results are not optimized or the impact of time on enterprise is neglected in the optimization. To solve these problems, a new multiobjective optimization reliability allocation method for machine tool is proposed in this paper. Firstly, the latest achievements about meta‐action are given, and meta‐action is set as the reliability allocation object. Secondly, more reasonable and comprehensive factors affecting reliability allocation are extracted. Thirdly, expert weight coefficient is brought to reduce the subjective impact of expert scoring. Fourthly, time factor is brought to make the optimized allocation results more reasonable and accurate. Finally, a numerical control (NC) machine tool made in China is taken as an example, with a comparison on the reliability allocation results of current methods and proposed method. The results verify the applicability, rationality, and accuracy of the proposed method, which lays a foundation for the subsequent study on the quality characteristics of machine tool based on meta‐action.
Charge‐dependent modulation of specific and nonspecific protein‐metal ion interactions in nanoelectrospray ionization mass spectrometry
Authors: Zheng Shihui , Yuan Siming , Hou Zhuanghao , Li Gongyu , Chen Yuting , Pan Yang , Liu Yangzhong , Huang Guangming
Published: May 2019

Rationale

Previous studies found that charge state could affect both specific and nonspecific binding of protein–metal ion interactions in nanoelectrospray ionization mass spectrometry (nESI‐MS). However, the two kinds of interactions have been studied individually in spite of the problem that they often coexist in the same system. Thus, it is necessary to study the effects of charge state on specific and nonspecific protein–metal ion interactions in one system to reveal more accurate binding state.

Methods

The HIV‐1 nucleocapsid protein (NCp7(31–55)) which can bind specifically and nonspecifically to Zn2+ served as the model to show the charge‐dependent protein–metal ion interactions. Hydrogen/deuterium exchange (HDX) and photodissociation (PD) were used to demonstrate that specific binding state was correlated with protein structure. In addition to NCp7(31–55), three other model proteins were used to investigate the reason for the charge‐dependent nonspecific binding.

Results

For specific binding, we proposed that protein ions with different charge states had different conformations. The HDX results showed that labile protons in the NCp7(31–55)–Zn complex were exchanged in a charge‐state‐dependent way. The PD experiments revealed differential fragment yields for different charge states. For nonspecific binding, higher charge states had more Zn2+ additions, but less SO42− additions. The effects of charge states on nonspecific binding levels were entirely the opposite for Zn2+ and SO42−. These results could reveal that the nonspecific binding was caused by electrostatic interaction.

Conclusions

For specific binding, NCp7(31–55) with lower charge states have folding and undenatured structures. The binding states of lower charge states can better reflect more native binding states. For nonspecific binding, when multiple metal ions adduct to proteins, the proteins have more net positive charges, which tend to generate higher charge ions during electrospray.
Assessing dual hair sampling for isotopic studies of grizzly bears
Authors: Ueda Momoko , Bell Lynne S.
Published: May 2019

Rationale

The stable isotope ratios of carbon (δ13C values), nitrogen (δ15N values) and sulfur (δ34S values) in bear hair can be used to obtain information on dietary history. Sample protocols often require hair sampling from multiple anatomical locations; however, there remains a question as to whether this is necessary for isotopic studies of hair. The purpose of this study was to determine whether significant differences can be observed for the δ13C, δ15N and δ34S values between paired hair samples taken from the rump and shoulder of grizzly bears (Ursus arctos).

Methods

Paired hair samples were collected from the rump and the shoulder of 81 grizzly bears in the Yukon, Canada. Hair samples were analyzed using a thermal combustion elemental analyzer coupled with a continuous flow isotope ratio mass spectrometer.

Results

Statistical comparisons of paired hair samples for both males and females showed no meaningful differences in δ13C, δ15N and δ34S values in hair taken from the rump and shoulder, and any observed differences fell within the instrumental error.

Conclusions

Based on these results, hair may be safely sampled on either the rump or the shoulder without loss of isotopic information and thus this finding allows for refinement of sampling.
Grazing high and low: Can we detect horse altitudinal mobility using high‐resolution isotope (δ13C and δ15N values) time series in tail hair? A case study in the Mongolian Altai
Authors: Lazzerini Nicolas , Coulon Aurélie , Simon Laurent , Marchina Charlotte , Noost Bayarkhuu , Lepetz Sébastien , Zazzo Antoine
Published: May 2019

Rationale

Carbon and nitrogen stable isotope time series performed in continuously growing tissues (hair, tooth enamel) are commonly used to reconstruct the dietary history of modern and ancient animals. Predicting the effects of altitudinal mobility on animal δ13C and δ15N values remains difficult as several variables such as temperature, water availability or soil type can contribute to the isotope composition. Modern references adapted to the region of interest are therefore essential.

Methods

Between June 2015 and July 2018, six free‐ranging domestic horses living in the Mongolian Altaï were fitted with GPS collars. Tail hairs were sampled each year, prepared for sequential C and N isotope analysis using EA‐IRMS. Isotopic variations were compared with altitudinal mobility, and Generalized Additive Mixed (GAMMs) models were used to model the effect of geographic and environmental factors on δ13C and δ15N values.

Results

Less than half of the pasture changes were linked with a significant isotopic shift while numerous isotopic shifts did not correspond to any altitudinal mobility. Similar patterns of δ13C and δ15N variations were observed between the different horses, despite differences in mobility patterns. We propose that water availability as well as seasonal availability of N2 fixing type plants primarily controlled horse hair δ13C and δ15N values, overprinting the influence of altitude.

Conclusions

Our study shows that altitudinal mobility is not the main factor that drives the variations in horse tail hair δ13C and δ15N values and that seasonal change in the animal dietary preference also plays an important role. It is therefore risky to interpret variations in δ13C and δ15N values of animal tissues in terms of altitudinal mobility alone, at least in C3–dominated environments.
Small hydropower dam alters the taxonomic composition of benthic macroinvertebrate assemblages in a neotropical river
Authors: Linares Marden Seabra , Assis Waldecy , de Castro Solar Ricardo Ribeiro , Leitão Rafael Pereira , Hughes Robert M. , Callisto Marcos
Published: May 2019

Hydropower dams substantially modify lotic ecosystems. Most studies regarding their ecological impacts are based on large dams and provide little information about the far more abundant effects of small hydropower dams. Our aim was to characterize the ecological effects of a small hydropower dam and run‐of‐the‐river reservoir on the structure of benthic macroinvertebrate assemblages in the Pandeiros River located in the neotropical savanna of Brazil. We tested the hypothesis that benthic macroinvertebrate assemblages in sites directly affected by the dam and reservoir would show a different taxonomic structure compared with those in free‐flowing sites. We expected to find sensitive native species associated with the free‐flowing sites, whereas resistant and non‐native invasive taxa were expected in impounded sites. We also explored associations between the presence of native and non‐native invasive taxa to each habitat type. We found that the structure of benthic macroinvertebrate assemblages was significantly different between free‐flowing and impounded sites. Also, we found that the dam and reservoir facilitated colonization of non‐native invasive species (Corbicula fluminea and Melanoides tuberculata) because only in those sites they were found in high abundance, in contrast to the free‐flowing sites. Although the environmental conditions imposed by the impoundment altered the structure of benthic macroinvertebrate assemblages, the effects were limited to sites closest to the dam. Our results highlight the necessity of understanding physical habitat changes caused by the presence and management of run‐of‐the‐river dams and reservoirs.
Bridge pier scour under pressure flow conditions
Authors: Carnacina Iacopo , Pagliara Stefano , Leonardi Nicoletta
Published: May 2019

The probability of pressurized flow conditions occurring in existing bridges is forecast to increase due to possible changes in extreme precipitation, storm surges, and flooding predicted under climate change scenarios. The presence of a pressure flow is generally associated with scouring processes in proximity to the bridge. Scouring can also occur around bridge piers, possibly causing infrastructure failure. Although there is a vast literature on bridge pier scour and pressure flow scour, only a few studies have investigated their combined effect. This study will provide a new overview of the main features of bridge pier scour under pressurized flow conditions, based on laboratory experiences. Special focus is placed on the analysis of the flow features under pressure and free surface conditions and to the temporal evolution of the scour. A comparison with existing literature data is also conducted. The results highlight the nonlinear nature of scour processes and the need to consider pressurized flow conditions during structural design, as the interaction between pressure flow and the bridge pier strongly influences scour features and leads to scour depths much greater than the sum of the individual scours created only by pressure flow or pier presence.
Model‐based standardization using an outcome model with random effects
Authors: Wang Zhongkai , Brumback Babette A. , Alrwisan Adel A. , Winterstein Almut G.
Published: May 2019

Model‐based standardization uses a statistical outcome model or exposure model to estimate a population‐average association that is unconfounded by selected covariates. With it, one can compare groups using a distribution of confounders identical in each group to that of a standard population. We develop an approach based on an outcome model, in which the mean of the outcome is modeled conditional on the exposure and the confounders. In our approach, there is a confounder that clusters the observations into a very large number of categories. We treat the parameters for the clusters as random effects. We use a between‐within model to account for the association of the random effects not only with the exposure but also with the cluster population sizes. We review alternative approaches presented in the literature, and we compare the outcome‐modeling approach to recently proposed exposure‐modeling approaches incorporating random effects. To illustrate, we use 2014 to compare proportions of acute respiratory tract infection diagnoses with an antibiotic prescription for emergency department versus outpatient visits, adjusting for confounding by unmeasured patient level variables and measured diagnosis‐level variables. We also present results of a simulation study.
Process Development and DFT‐Assisted Mechanism of the Vapour Phase Ammoxidation of 2,6‐Dichlorotoluene to 2,6‐Dichlorobenzonitrile over the V2O5/γ‐Al2O3 Catalyst
Authors: Dwivedi Ritambhara , Kumar Ashok , Khare Savita , Prasad Rajendra
Published: May 2019

Ammoxidation of 2,6‐dichlorotoluene (2,6‐DCLT) to 2,6‐dichlorobenzonitrile (2,6‐DCLBN) over V2O5/γ‐Al2O3 catalyst has been carried out in a fixed bed reactor. A maximum conversion of 96% of (2,6‐DCLT) and 79% yield to 2,6‐dichlorobenzonitrile have been obtained at a temperature of 425 °C, Air : 2,6‐DCLT mole ratio of 22 : 1 and NH3 : 2,6‐DCLT mole ratio of 11 : 1. A DFT theory computations have been performed with the objective of finding a mechanism of the reaction, activation energy and transition state for different reactions. Abstraction of C−H bond with an activation energy of 64.60 kcal mol−1 was found to be rate determining step. A new approach has been suggested for the reoxidation of the catalyst which supports reoxidation of every step associated with dehydration of species during the reaction. This finding is a contrary of the previous studies which assume reoxidation of the catalyst at the end of all reactions. Rapid reoxidation of the catalyst surface to release water is found to be the driving force for all reactions involving the cleavage of C−H or N−H bonds.
A Self‐Assembled Flower‐Like Structure of Nickel‐Cobalt Phosphide Nanosheets Supported on Nickel Foam for Electrochemical Hydrogen Evolution Reaction
Authors: Li Shengjuan , Zou Yicheng , Li Lei , Dong Yongguang , Zhu Yufang
Published: May 2019

In this study, flower‐like nickel‐cobalt phosphide (NiCoP) on Ni foam (flower‐like NiCoP/NF) was fabricated via a two‐step process, including hydrothermal and phosphorization. Hydrogen evolution reaction (HER) measurements show that such flower‐like NiCoP/NF is a highly efficient and stable electrocatalyst, which can keep high activity for more than 20 h at ambient temperature. Scanning electron microscope (SEM) images show that flower‐like NiCoP/NF uniformly covered the Ni foam surface. In the hydrothermal step, X‐ray photoelectron spectroscopy (XPS) results show that partial Co2+ ions from Co(NO3)2⋅6H2O were oxidized to Co3+ ions in the ethanol‐water solution. Meanwhile, NO3− ions from Ni(NO3)2⋅6H2O and Co(NO3)2⋅6H2O triggered the ethanol‐water solution to release OH− ions, which subsequently reacted with Ni2+, Co2+ and Co3+ ions to generate NiCo‐OH precipitation. Subsequently, in the phosphorization step NiCo‐OH was converted to NiCoP nanosheets by NaH2PO2 at a low temperature of 350 °C. The two‐step method employed in the present work avoids an addition of alkali sources or precipitators to the hydrothermal reaction solution, which is favorable for environmental protection strategies and sustainable development principles.
Synthesis and Characterization of New Inorganic‐Organic Hybrid Nanocomposite PMo11Cu@MgCu2O4@CS as an Efficient Heterogeneous Nanocatalyst for ODS of Real Fuel
Authors: Rezvani Mohammad Ali , Shaterian Maryam , Aghbolagh Zahra Shokri , Akbarzadeh Fereshteh
Published: May 2019

In this work, a new nanocomposite (PMo11Cu@MgCu2O4@CS) was synthesized by reaction of copperII‐monosubstituted phosphomolybdate (PMo11Cu), magnesiocopperite (MgCu2O4) and Chitosan (CS) via the sol‐gel method. The assembled nanocomposite was characterized by FTIR, XRD, SEM. The catalytic activity of the nanocomposite was tested on oxidative desulfurization (ODS) of real gasoline in the presence of CH3COOH/H2O2 in the volume ratio of 1/2 as an oxidant. Additionally, the results were compared with the oxidation reaction of prepared model sulfur compounds at the same conditions. The ODS results showed that immobilized of PMo11Cu on the CS and MgCu2O4 nanoceramic increased the efficiency and activity of the PMo11Cu in the removal of organic sulfur compounds (OSCs). The PMo11Cu@CS @MgCu2O4 could be reused for at least five times without notable reduction in efficiency of ODS system. This investigation presents a promising approach to the efficient removal of OSCs from gasoline using PMo11Cu@MgCu2O4@CS catalyst under mild reaction conditions.
[PVP‐SO3H] HSO4: An Efficient Polymeric Solid Acid Catalyst for the Formylation and N‐Boc Protection Reactions
Authors: Pakpour‐Roudsari Fatemeh , Seddighi Mohadeseh , Shirini Farhad , Tajik Hassan
Published: May 2019

In the present work, the formylation of a variety of amines and alcohols was performed using [PVP‐SO3H] HSO4 as a powerful solid acid catalyst under solvent‐free conditions. Under this catalytic condition, N‐Boc protection of amines was also successfully done at room temperature. Easy and economical methodology, short reaction times, high yields, chemo‐selectivity, high TOF and easy workup are some of the advantages of this work. Furthermore, [PVP‐SO3H]HSO4 can be easily separated and reused for several times without considerable loss of its catalytic activity.
Rational Design of Semi‐Synthetic Protein Complexes with the Defined Oligomeric State
Authors: Sandanaraj Britto S , Reddy Mullapudi Mohan , Rao Kasuladevu Jagannadha , Bhandari Pavankumar Janardhan
Published: May 2019

Protein oligomers are ubiquitous in nature and play an essential role in various biological processes. Recently, there is an enormous interest to custom‐make synthetic protein oligomers through the bottom‐up approach. In this regard, genetic methods have made tremendous progress in the last decade. In comparison, only few chemical methods currently exist for this purpose. Herein, we report a modular synthetic strategy for the design of facially amphiphilic globular protein‐synthetic peptide conjugates. The self‐assembly of these bioconjugates is driven by strong hydrophobic interaction of the peptide domain. The size, molecular mass and oligomeric state of semi‐synthetic protein complexes strongly depend on size and surface charge of a globular protein as well as the length of the hydrophobic peptide domain. A systematic structure‐property relationship study of these semi‐synthetic proteins should shed more light on the understanding of various non‐covalent forces, which governs the oligomerization processes of naturally occurring proteins.
Designing Highly Efficient and Long‐Term Durable Electrocatalyst for Oxygen Evolution by Coupling B and P into Amorphous Porous NiFe‐Based Material
Authors: Hu Fei , Wang Haiyun , Zhang Yan , Shen Xiaochen , Zhang Guanghui , Pan Yanbo , Miller Jeffrey T. , Wang Kun , Zhu Shengli , Yang Xianjin , Wang Chengming , Wu Xiaojun , Xiong Yujie , Peng Zhenmeng
Published: May 2019

Oxygen evolution reaction (OER) is of great significance for hydrogen production via water electrolysis, which, however, demands development of highly active, durable, and cost‐effective electrocatalysts in order to stride into a renewable energy era. Herein, highly efficient and long‐term durable OER by coupling B and P into an amorphous porous NiFe‐based electrocatalyst is reported, which possesses an amorphous porous metallic bulk structure and high corrosion resistance, and overcomes the issues associated with currently used catalyst nanomaterials. The PB codoping in the activated NiFePB (a‐NiFePB) delocalizes both Fe and Ni at Fermi energy level and enhances p–d hybridization as simulated by density functional theory calculations. The harmonized electronic structure and unique porous framework of the a‐NiFePB consequently improve the OER activity. The activated NiFePB thus exhibits an extraordinarily low overpotential of 197 mV for harvesting 10 mA cm−2 OER current density and 233 mV for reaching 100 mA cm−2 under chronopotentiometry condition, with the Tafel slope harmoniously conforming to 34 mV dec−1. Impressive long‐term stability of this new catalyst is evidenced by only limited activity decay after 1400 h operation at 100 mA cm−2. This work strategically directs a way for heading up a promising energy conversion alternative.
PAxSPL: A feature retrieval process for software product line reengineering
Authors: Marchezan Luciano , Macedo Rodrigues Elder , Bernardino Maicon , Paulo Basso Fábio
Published: May 2019

Software product lines (SPLs) are a well‐known solution to systematically create reusable software products. Among the approaches to create an SPL, the extractive approach is usually used when the organization already has a set of similar systems. These systems are analyzed to extract, categorize, and group their common and variant features throughout the SPL reengineering process. As there are different scenario variables, such as available artifacts and team experience, the activities and techniques used to perform these tasks may change. This may increase the effort and decrease the quality of retrieved features when users with low experience in SPL reengineering perform such tasks. However, there is a lack of a process supporting these tasks considering different scenarios. Therefore, we specify the Prepare, Assemble, and Execute Process for SPL Reengineering (PAxSPL), a process that provides support to prepare, assemble, and execute feature retrieval throughout the analysis of documentation and team experience. To initially evaluate PAxSPL, we conducted and reported an exploratory case study in a real development environment. The results indicated that our proposal helps in the assembly of a feature retrieval process according to user needs. Results were important to identify points for improvement in PAxSPL. We also could use the information gathered to improve the guidelines and provide this information to be used as basis of comparison for future users.
Study on depositing SiO2 nanoparticles on the surface of jute fiber via hydrothermal method and its reinforced polypropylene composites
Authors: Chen Haiyan , Cui Yihua , Liu Xuan , Zhang Miao , Hao Senjie , Yin Yuehong
Published: May 2019

To improve the interfacial compatibility of jute fiber reinforced polypropylene (PP) composites, hydrothermal method was used to deposit SiO2 nanoparticles on the surface of pretreated jute fibers and the effect of reaction factors (tetraethoxysilane [TEOS] concentration, ammonia concentration, and reaction temperature) on the deposition of SiO2 nanoparticles were evaluated. The results of FTIR, XRD, SEM, and TEM showed that the amorphous SiO2 nanoparticles with an average particle size of 65.0 nm were successfully deposited on the surface of jute fibers at the TEOS/H2O volume ratio of 1:2, ammonia of 0.55 M, reaction temperature of 100 °C (0.15 MPa) for 5 h. Compared with the sol–gel method, SiO2 nanoparticles obtained by the hydrothermal method possessed smaller particle size and were less agglomerated, which can better fill in the surface defects of the jute fibers and result in a 12.9% increase in the tensile strength. The study on the mechanical properties and interface performance of the jute fiber reinforced PP composites indicated that the interfacial compatibility between jute fibers and PP was obviously improved. The tensile and impact strength of the composites reinforced with nano‐SiO2 deposited jute fibers were increased by 26.87% and 25.65%, respectively, compared with the untreated jute fibers. J. VINYL ADDIT. TECHNOL., 26:43–54, 2020. © 2019 Society of Plastics Engineers
Measuring the impact of additional instrumentation on the skill of numerical weather prediction models at forecasting wind ramp events during the first Wind Forecast Improvement Project (WFIP)
Authors: Akish Elena , Bianco Laura , Djalalova Irina V. , Wilczak James M. , Olson Joseph B. , Freedman Jeff , Finley Catherine , Cline Joel
Published: May 2019

The first Wind Forecast Improvement Project (WFIP) was a DOE and NOAA‐funded 2‐year‐long observational, data assimilation, and modeling study with a 1‐year‐long field campaign aimed at demonstrating improvements in the accuracy of wind forecasts generated by the assimilation of additional observations for wind energy applications. In this paper, we present the results of applying a Ramp Tool and Metric (RT&M), developed during WFIP, to measure the skill of the 13‐km grid spacing National Oceanic and Atmospheric Administration/Earth System Research Laboratory (NOAA/ESRL) Rapid Refresh (RAP) model at forecasting wind ramp events. To measure the impact on model skill generated by the additional observations, controlled data‐denial RAP simulations were run for six separate 7 to 12‐day periods (for a total of 55 days) over different seasons.

The RT&M identifies ramp events in the time series of observed and forecast power, matches in time each forecast ramp event with the most appropriate observed ramp event, and computes the skill score of the forecast model penalizing both timing and amplitude errors. Because no unique definition of a ramp event exists (in terms of a single threshold of change in power over a single time duration), the RT&M computes integrated skill over a range of power change (Δp) and time period (Δt) values.

A statistically significant improvement of the ramp event forecast skill is found through the assimilation of the special WFIP data in two different study areas, and variations in model skill between up‐ramp versus down‐ramp events are found.
Parameter identification in elasto‐plasticity: distance between parameters and impact of measurement errors
Authors: Shutov Alexey V. , Kaygorodtseva Anastasia A.
Published: May 2019

A special aspect of parameter identification in finite‐strain elasto‐plasticity is considered. Namely, we analyze the impact of the measurement errors on the resulting set of material parameters. In order to define the sensitivity of parameters with respect to the measurement errors, a mechanics‐based distance between two sets of parameters is introduced. Using this distance function, we assess the reliability of certain parameter identification procedures. The assessment involves introduction of artificial noise to the experimental data; the noise can be both correlated and uncorrelated. An analytical procedure to speed up Monte Carlo simulations is presented. As a result, a simple tool for estimating the robustness of parameter identification is obtained. The efficiency of the approach is illustrated using a model of finite‐strain viscoplasticity, which accounts for combined isotropic and kinematic hardening. It is shown that dealing with correlated measurement errors, most stable identification results are obtained for non‐diagonal weighting matrix. At the same time, there is a conflict between the stability and accuracy.
The CKM parameters in the SMEFT
Authors: Descotes-Genon Sébastien , Falkowski Adam , Fedele Marco , González-Alonso Martín , Virto Javier
Published: May 2019

Abstract

The extraction of the Cabibbo-Kobayashi-Maskawa (CKM) matrix from flavour observables can be affected by physics beyond the Standard Model (SM). We provide a general roadmap to take this into account, which we apply to the case of the Standard Model Effective Field Theory (SMEFT). We choose a set of four input observables that determine the four Wolfenstein parameters, and discuss how the effects of dimension-six operators can be included in their definition. We provide numerical values and confidence intervals for the CKM parameters, and compare them with the results of CKM fits obtained in the SM context. Our approach allows one to perform general SMEFT analyses in a consistent fashion, independently of any assumptions about the way new physics affects flavour observables. We discuss a few examples illustrating how our approach can be implemented in practice.
Leading higher-derivative corrections to Kerr geometry
Authors: Cano Pablo A. , Ruipérez Alejandro
Published: May 2019

Abstract

We compute the most general leading-order correction to Kerr solution when the Einstein-Hilbert action is supplemented with higher-derivative terms, including the possibility of dynamical couplings controlled by scalars. The model we present depends on five parameters and it contains, as particular cases, Einstein-dilaton-Gauss-Bonnet gravity, dynamical Chern-Simons gravity and the effective action coming from Heterotic Superstring theory. By solving the corrected field equations, we find the modified Kerr metric that describes rotating black holes in these theories. We express the solution as a series in the spin parameter χ, and we show that including enough terms in the expansion we are able to describe black holes with large spin. For the computations in the text we use an expansion up to order χ
14, which is accurate for χ < 0.7, but we provide as well a Mathematica notebook that computes the solution at any given order. We study several properties of the corrected black holes, such as geometry of the horizon, ergosphere, light rings and scalar hair. Some of the corrections violate parity, and we highlight in those cases plots of horizons and ergospheres without ℤ2 symmetry.
Erfolgreicher Wissenserwerb im ersten Semester Physik
Authors: Woitkowski David
Published: May 2019

Der Erwerb von Fachwissen auf einem Niveau, welches auf die typischen komplexen und abstrakten Problemstellungen der Universitätsphysik angewandt werden kann, stellt eine zentrale Herausforderung in der Studieneingangsphase dar. Verschiedene Probleme dieser Phase, wie die hohen Abbruch-/Schwundquoten, können auf fachliche Schwierigkeiten in diesem Kontext zurückgeführt werden. Auch im späteren Studium wird immer wieder konzeptionell auf dem hier gelernten Fachwissen aufgebaut, so dass diese Phase als kritisch angesehen werden kann.

Die vorliegende Studie erhebt längsschnittlich das physikalische Fachwissen (Mechanik) bei 122 Physikstudierenden zu Beginn und Ende des ersten Studiensemesters. Die Studierenden können einem Niveaumodell zugeordnet werden, welches beschreibt, mit Aufgaben welcher Komplexität sie jeweils erfolgreich umgehen können.

Diese Niveaus stellen einerseits ein Bewertungskriterium für die Qualität des vorhandenen Fachwissens dar und können so ein an Anforderungsmerkmalen orientiertes Zielkriterium für erfolgreichen Fachwissenserwerb liefern. Andererseits können die Niveaus eine erste Einschätzung davon liefern, welche Ausprägung des Vorwissen prädiktiv für erfolgreichen Wissenserwerb ist.

Die Daten sprechen für einen wesentlichen Einfluss physikalischen und mathematischen Vorwissens auf die mittlere weitere Wissensentwicklung, insbesondere zeigen sich Hinweise auf eine additive Prädiktionskraft des schulischen Vorwissens für den Erwerb universitären Wissens bis Ende des ersten Semesters. Die Ergebnisse legen nahe, dass vor allem die Fähigkeit zum Umgang mit komplexen Problemstellungen prädiktiv für das universitäre Physiklernen ist – auch und gerade, wenn es im Rahmen der schulischen Physik erlernt wurde.
New taxa and revised stratigraphic distribution of the crinoid fauna from Anticosti Island, Québec, Canada (Late Ordovician-early Silurian)
Authors: Ausich William I. , Cournoyer Mario E.
Published: May 2019

End-Ordovician extinctions had a profound effect on shallow-water benthic communities, including the Crinoidea. Further, recovery after the extinctions resulted in a macroevolutionary turnover in crinoid faunas. Anticosti Island is the most complete Ordovician-Silurian boundary section recording shallow-water habitats. Both new taxa and changes in Anticosti Island stratigraphic nomenclature are addressed herein. New taxa includeBecsciecrinus groulxin. sp.,Bucucrinus isotaloin. sp.,Jovacrinus clarkin. sp.,Plicodendrocrinus petrykin. sp.,Plicodendrocrinus martinin. sp.,Thalamocrinus daoustaen. sp., andLateranicrinus saintlaurentin. gen. n. sp. The status ofXenocrinus rubusas a boundary-crossing taxon is confirmed, range extensions of several taxa are documented, and the distribution of crinoids with the revised stratigraphic nomenclature is documented.

UUID:http://zoobank.org/19613a44-ec69-47d7-88ab-fcf88ba771f0.
The Effects of Yaw on Conical Wings at High Supersonic Speeds
Authors: Hillier R.
Published: May 2019

In recent papers Squire has presented results for the shock shape and pressure distribution on the lower surface of unyawed, lifing, conical bodies with sharp leading edges. The work, a development of Messiter’s first-order correction to Newtonian theory, was successfully applied to wings of diamond and caret section. This paper shows how the method may be used to include the effects of yaw. Results are presented here for the flat wing and some biconvex sections. Comparisons are made with experiment for both the flat and biconvex wings and agreement is shown to be good.
The Dynamical Behaviour of a Flexible Cable in a Uniform Flow Field
Authors: Huffman R. R. , Genin Joseph
Published: May 2019

A non-linear mathematical model for the study of the dynamics of an extensible cable subjected to aerodynamic forces generated by a uniform flow field is formulated. Solutions are found considering large displacement caused by suddenly applied loads (i.e., gusts, shock waves, turbulence) for a range of flow speeds and cable lengths. Transition from overdamped to oscillatory motion is observed when flow speed and cable length are increased and decreased respectively. The stability of the system is discussed.
Experimental Results for Waveriders in Certain Off-Design Conditions
Authors: Squire L. C.
Published: May 2019

For caret waveriders at the design condition the attached shock wave in the plane of the leading edges may correspond to either a strong or a weak oblique shock wave when viewed normal to the edges. In cases when the design shock wave corresponds to the strong oblique shock the off-design behaviour of the wing is not completely understood. In this note some measured results are analysed in an attempt to understand this off-design behaviour.
Vibration Characteristics of Pre-twisted Blades of Asymmetrical Aerofoil Cross-Section
Authors: Carnegie W. , Dawson B.
Published: May 2019

The natural frequencies and mode shapes of vibration of cantilever aerofoil cross-section blades of pre-twist angle in the range 0 to 90 degrees are obtained. The beams are 152·4 mm long and the width / thickness ratio is such that they may be regarded as slender. Theoretical frequency ratios and mode shapes of vibration, neglecting shear and rotary inertia effects, are obtained for two sets of beams, one with clockwise pre-twist relative to the root cross-section and the other with anti-clockwise pre-twist. The effect of variation in the value of the centre-of-flexure coordinates upon the natural frequency ratios and mode shapes of vibration is investigated. The theoretical results are compared to corresponding experimental results.
Simplified Presentation of Preston Tube Calibration
Authors: Head M. R. , Ram V. Vasanta
Published: May 2019

Two alternative presentations are given of Patel’s Preston tube calibration. In the first, Δp/τw is tabulated as a function of Δpd2/ρν2; in the second, cf is plotted as a function of Δp/½ρU2 and Ud/ν, so that values of cf, can be read off directly.
The Three-Dimensional Turbulent Boundary Layer on an Infinite Yawed Wing
Authors: Nash J. F. , Tseng R. R.
Published: May 2019

This paper presents the results of some calculations of the incompressible turbulent boundary layer on an infinite yawed wing. A discussion is made of the effects of increasing lift coefficient, and increasing Reynolds number, on the displacement thickness, and on the magnitude and direction of the skin friction. The effects of the state of the boundary layer (laminar or turbulent) along the attachment line are also considered.

A study is made to determine whether the behaviour of the boundary layer can adequately be predicted by a two-dimensional calculation. It is concluded that there is no simple way to do this (as is provided, in the laminar case, by the principle of independence). However, with some modification, a two-dimensional calculation can be made to give an acceptable numerical representation of the chordwise components of the flow.
A Method for Reducing the Base Drag of Wings with Blunt Trailing Edge
Authors: Tanner M
Published: May 2019

To study the possibilities of reducing the base drag of profiles with a blunt trailing edge, experiments were performed in two low-speed wind-tunnels at the DFVLR-AVA, Göttingen, some on models between walls and some on rectangular wings with an aspect ratio of 2.5. The results show that the mean base pressure can be increased, and so the base drag reduced, by using a special form of the blunt trailing edge. The variation of local base pressure along the span, and the way in which this variation is influenced by the form of the trailing edge, is also shown. Some results for the total drag and lift are also indicated.
Numerical Results for the Initial Buckling of Some Stiffened Panels in Compression
Authors: Williams F W , Wittrick W H
Published: May 2019

In previous papers the basis of a matrix approach to the initial buckling or vibration of prismatic structures consisting of a series of thin flat rectangular plates rigidly connected together along their longitudinal edges has been developed. The present paper provides numerical results for the buckling, under uniform longitudinal compression, of a series of panels with unflanged or flanged integral stiffeners, or with Z-section stiffeners; the results are compared with those obtained by other methods and with published results, including an appropriate Royal Aeronautical Society Structures Data Sheet. It was found that considerable inaccuracies can arise from the usual methods of analysis and the authors believe that these justify the use of computer programmes, such as the ones used to obtain the results of this paper, at least at the final design stage.
Lower Bounds for the Pressure Jumps of the Shock Waves of a Supersonic Transport of Given Length
Authors: Jones L B
Published: May 2019

In an earlier paper the lower bounds for the pressure jumps across the bow shock waves of a supersonic transport were derived, it being assumed that all the shocks had coalesced into either the bow or rear shocks, but not that the shocks were at such a great distance (asymptotic) that they had the same strength. In this paper the results of the earlier work are developed so that the lower bounds for the pressure jumps across shock waves propagating through a homogeneous atmosphere are determined by considering bow and rear shock waves simultaneously.
Are Moderates Better Representatives than Extremists? A Theory of Indirect Representation
Authors: PATTY JOHN W. , PENN ELIZABETH MAGGIE
Published: May 2019

Few, if any, elected representatives are capable of unilaterally implementing their platforms. Rather, they choose between options generated by other actors and/or external events. We present a theory of voters’ preferences over representatives who will cast votes on their behalf, and show that in this setting voters’ preferences over candidates’ platforms will not look like voters’ preferences over policies. We demonstrate that these induced preferences for representation tend to favor more extreme representatives, and we present two models of electoral competition in which induced preferences over representatives lead to elite polarization.
Technological Change and Religious Unification
Authors: Mesthene Emmanuel G.
Published: May 2019

The phrase “religious unification” in its title does not mean that this paper is about ecumenism or that it is a plea for religious unity. It is not intended as a contribution to piety or to religious education, but to theological clarification. That is, I use the word “unification” in its intellectual sense, not in a practical or political sense.
Moral Argument in the New Morality
Authors: Kliever Lonnie D.
Published: May 2019

The new morality like every other new thing in this fast-moving time seems to have declined in notoriety and disciples with age. But there are still good reasons for recognizing and exploring a new morality in contemporary Christian ethics. These reasons will only become clear later, but they can be set down now by way of introducing the analysis that follows.
Analysis of Methods of Potmaking in Archaeology
Authors: Franken H. J.
Published: May 2019

A good deal of information is being collected about the potter's craft in many parts of the world. Some work has been done on the analysis of potmaking in antiquity, but as far as the present writer knows, the importance of this type of analysis for archaeological studies has not been critically investigated. This paper intends to present the reader with the results of research into the methods of potmaking in two cultural periods in Palestine, as well as with some of the problems that came up during this research. The two periods concerned are the Early Iron Age (ca. 1200–1000 B.C.) and the Medieval period from the beginning of the Islamic conquest to ca. 1500 A.D.
Notes on Some Cypriote Priests Wearing Bull-Masks
Authors: Karageorghis Vassos
Published: May 2019

The bull was known in Cyprus as the symbol of the god of fertility already in the Early Bronze Age (3rd millennium B.C.). The bucranium, which is the most characteristic part of this animal, appears as a religious symbol on a number of religious documents from Cyprus, namely, models of sanctuaries where bucrania are represented on wooden poles, forming the centre of worship (Fig. 1). In the Aegean world, particularly in Minoan Crete, the head of the sacrificed bull played an important part in religious ritual, especially during the second millennium B.C. In the Near East the idea of fertility impressed most profoundly prehistoric man, and consequently the bull appears in the religious iconography as early as the 7th millennium. The idea of entering into a direct association with the god by putting on the divine image led to the invention of masks which were worn during religious rituals. Monsters with bull's heads appear both in Oriental and Aegean religions already in prehistoric times. The “bull-man” in the Near East and the “Minotaur” in the Aegean dominated for centuries the religious scenes as they appear in both regions, particularly in glyptic. This conception is more evident in later dramatic performances, which succeeded ritual, where the mask was of primary importance.
Kleine Beiträge Zur Siedlungsgeschichte der Stämme Asser und Juda
Authors: Kuschke Arnulf
Published: May 2019

Im Sommer 1968 hatte ich erstmals Gelegenheit, eine Reihe von antiken Ortslagen im westlichen Untergaliläa und in der Šefēlāh, dem westlichen Hügelland von Juda, aufzusuchen, die für die Lokalisierungsprobleme von Jos. 19, 24–31 und Jos. 15, 33–36 von Interesse sind.