bluuebunny/crossref_metadata_2025 huggingface dataset:
Mesozoic exhumation history of the Grenvillian Oaxacan Complex, southern Mexico
Authors: Abdullin Fanis , Solari Luigi , Solé Jesús , Ortega‐Obregón Carlos
Published: August 2020

We present the first fission‐track results from the Grenvillian Oaxacan Complex, southern Mexico. Time–temperature modelling of the data indicates that two significant Mesozoic cooling episodes are recorded in the Oaxacan Complex and these are interpreted as resulting from exhumation. The older cooling event took place from the Late Triassic to Middle Jurassic and is possible linked to the break‐up of Pangea (including the initial opening of the Gulf of Mexico during the Jurassic). The younger exhumation period in the Early Cretaceous is contemporaneous with the final stages of rifting of the Gulf of Mexico. Key stratigraphic records also provide independent evidence for these exhumation episodes. In our view, both Mesozoic rapid exhumation events were controlled by the activity of the Caltepec Fault Zone and the Oaxaca Fault. Our data suggest that both these large fault systems have remained active since, at least, the Late Triassic.
Pre‐implantation genetic testing for aneuploidy: the past, present and future
Authors: L’Heveder Ariadne , Jones Benjamin P , Naja Roy , Serhal Paul , Ben Nagi Jara
Published: August 2020

Key content

Embryonic aneuploidy is often found in women undergoing assisted reproduction and is a common cause of poor outcomes, particularly in women of advanced maternal age and those with recurrent miscarriage and repetitive implantation failure.

The aim of pre‐implantation genetic testing for aneuploidy (PGT‐A) is to select the most competent embryo for transfer, thus improving reproductive outcome.

Initial PGT‐A techniques failed to show an improvement in delivery rates and, in some trials, demonstrated inferior outcomes; however, advances in technology, combined with robust culture media and vitrification techniques, have significantly improved outcomes.

Recent debate has argued for the increased clinical application of PGT‐A, particularly in women of advanced maternal age; we provide an overview of PGT‐A, including its past and associated limitations, the evolution in technology and latest outcomes, and address potential future implications.

Learning objectives

To understand the rationale behind the use of PGT‐A.

To review the evidence against and in favour of PGT‐A.

To understand the new techniques being used and how these have led to emerging evidence in favour of PGT‐A.

Ethical issues

Risk of damage to embryos during biopsying process.

PGT‐A may result in either no embryos available for transfer or only embryos displaying mosaicism being available to transfer, with little long‐term data on the outcomes of transferring mosaic embryos.

PGT‐A increases the cost of an already expensive treatment.
Another building block in the plant cell wall: Barley xyloglucan xyloglucosyl transferases link covalently xyloglucan and anionic oligosaccharides derived from pectin
Authors: Stratilová Barbora , Šesták Sergej , Mravec Jozef , Garajová Soňa , Pakanová Zuzana , Vadinová Kristína , Kučerová Danica , Kozmon Stanislav , Schwerdt Julian G. , Shirley Neil , Stratilová Eva , Hrmova Maria
Published: August 2020

We report on the homo‐ and hetero‐transglycosylation activities of the HvXET3 and HvXET4 xyloglucan xyloglucosyl transferases (XET; EC 2.4.1.207) from barley (Hordeum vulgareL.), and the visualisation of these activities in young barley roots using Alexa Fluor 488‐labelled oligosaccharides. We discover that these isozymes catalyse the transglycosylation reactions with the chemically defined donor and acceptor substrates, specifically with the xyloglucan donor and the penta‐galacturonide [α(1‐4)GalAp]5acceptor – the homogalacturonan (pectin) fragment. This activity is supported by 3D molecular models of HvXET3 and HvXET4 with the docked XXXG donor and [α(1‐4)GalAp]5acceptor substrates at the −4 to +5 subsites in the active sites. Comparative sequence analyses of barley isoforms and seed‐localised TmXET6.3 from nasturtium (Tropaeolum majusL.) permitted the engineering of mutants of TmXET6.3 that could catalyse the hetero‐transglycosylation reaction with the xyloglucan/[α(1‐4)GalAp]5substrate pair, while wild‐type TmXET6.3 lacked this activity. Expression data obtained by real‐time quantitative polymerase chain reaction ofHvXETtranscripts and a clustered heatmap of expression profiles of the gene family revealed thatHvXET3andHvXET6co‐expressed but did not share the monophyletic origin. Conversely,HvXET3andHvXET4shared this relationship, when we examined the evolutionary history of 419 glycoside hydrolase 16 family members, spanning monocots, eudicots and a basal Angiosperm. The discovered hetero‐transglycosylation activity in HvXET3 and HvXET4 with the xyloglucan/[α(1‐4)GalAp]5substrate pair is discussed against the background of roles of xyloglucan‐pectin heteropolymers and how they may participate in spatial patterns of cell wall formation and re‐modelling, and affect the structural features of walls.
Understanding occult hepatitis C infection
Authors: An Timothy , Dean Melinda , Flower Robert , Tatzenko Tayla , Chan Hiu Tat , Kiely Philip , Faddy Helen M.
Published: August 2020

Background

Occult hepatitis C infection (OCI) is a type of hepatitis C virus (HCV) infection, defined as the presence of HCV RNA in hepatocytes or peripheral blood mononuclear cells (PBMCs) and the absence of HCV RNA in serum.

Study Design and Methods

A literature review was conducted to identify articles that characterized OCI as a disease, including its epidemiology, mode of transmission, pattern of infection, progression, and treatment.

Results

OCI patients experience a milder degree of inflammatory and cirrhotic changes than patients with chronic hepatitis C. OCI is transmissible parenterally both in vivo and in vitro, however the duration and outcome of OCI remains unclear. OCI is most consistently found in patients with previous hepatitis C disease and hemodialysis patients. Beyond the at‐risk populations, OCI has also been demonstrated among healthy individuals and blood donors.

Conclusions

This review summarises our current understanding of OCI and suggests areas for further research to improve our understanding of this phenomenon, including a better understanding of its epidemiology and full clinical course. The current understanding of OCI and its clinical implications remain limited. Further standardized detection methods, ongoing surveillance, and investigation of its potential transmissions are required.
Risk of transmission of severe acute respiratory syndrome coronavirus 2 by transfusion: A literature review
Authors: Leblanc Jean‐François , Germain Marc , Delage Gilles , OʼBrien Sheila , Drews Steven J. , Lewin Antoine
Published: August 2020

Severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) is a novel human coronavirus responsible for coronavirus disease 2019 (COVID‐19). The emergence of this virus in Wuhan, China, at the end of 2019 and its worldwide spread to reach the pandemic stage has raised concerns about the possible risk that it might be transmissible by transfusion. This theoretical risk is further supported by reports of the detection of viral RNA in the blood of some infected individuals. To further address this risk, a thorough PubMed literature search was performed to systematically identify studies reporting data on the detection of SARS‐CoV‐2 RNA in blood or its components. Complementary searches were done to identify articles reporting data on the in vitro infectivity of blood components. At least 23 articles presenting data on the detection of SARS‐CoV‐2 RNA in blood, plasma, or serum were identified. Of these, three studies reported on blood donors with COVID‐19 infection identified after donation, and no cases of transfusion transmission were identified. A few studies mentioned results of in vitro infectivity assays of blood components in permissive cell lines, none of which were able to detect infectious virus in blood or its components. Complementary searches have identified reports demonstrating that the correlation between the presence of viral RNA in a biologic sample and infectivity requires a minimal RNA load, which is rarely, if ever, observed in blood components. Overall, the available evidence suggests that the risk of transmission of SARS‐CoV‐2 by transfusion remains theoretical.
Molecular phylogeny and divergence of major clades in the Puntius complex (Teleostei: Cypriniformes)
Authors: Ren Qiu , Yang Lei , Chang Chia‐Hao , Mayden Richard L.
Published: August 2020

Puntius sensu lato (s.l.) was one of the most speciose genera in the family Cyprinidae. There are around 120 valid species widely distributed in South‐East and South Asia, and South China. Puntius has long been known as an artificial assemblage and ‘catch‐all’ genus in which a large number of small, unrelated cyprinids have been placed. With new species and genera being described each year, obtaining detailed knowledge of the phylogenetic relationships of this complex is critically important in the assessment of a natural classification. In the present study, two mitochondrial and four nuclear genes were used to examine the inter‐specific and inter‐generic relationships of the Puntius complex and to test the monophyly of the current genera. Divergence time analysis was performed to explore the origin, evolution, and divergence of major clades in Puntius s.l. Results revealed that the genera Puntius seusu stricto (s.s.), Systomus, Pethia, Haludaria, Desmopuntius and Puntigrus were monophyletic with high support. However, monophyly of Barbodes, Striuntius and Sahyadria was not supported. Dawkinsia and Sahyadria formed a highly supported clade. Puntius semifasciolatus and P. snyderi from South China and Taiwan represent a new lineage. Inferences from divergence time analysis indicated that Puntius s.l. likely dated to early Miocene. Major clades in Puntius s.l. diverged during Miocene as well.
Incipient genetic divergence or cryptic speciation? Procamallanus (Nematoda) in freshwater fishes (Astyanax)
Authors: Santacruz Ana , Ornelas‐García Claudia Patricia , Pérez‐Ponce de León Gerardo
Published: August 2020

Hosts provide the main environmental traits parasites have to deal with, resulting in covariation between both associates at both micro‐ and macro‐evolutionary scales; phylogenetic analyses of highly host‐specific parasites have shown that parasite and host phylogeny might be highly congruent, and adaptation of a host species to new environments may lead to concordant changes of their parasites. Procamallanus (Spirocamallanus) neocaballeroi is a highly host‐specific parasitic nematode of the Neotropical freshwater fish genus Astyanax in Mexico. One of the host species of the nematode is the emblematic Mexican tetra, A. mexicanus, which exhibits two contrasting phenotypes, a cave‐dwelling morph (with troglomorphic features), and the surface‐dwelling morph; other congeneric species inhabit rivers and lakes, and some of them occur in sympatry, displaying trophic specializations. Here, we explored the hypothesis that contrasting environments (surface rivers vs cave rivers), and host morphological divergence (sympatric ecomorphs in a lacustrine environment) might result in the divergence of their parasites, even though the hosts maintain a cohesive genetic structure as the same species. To test the hypothesis, several populations of Astyanax spp. were sampled to search for P. (S.) neocaballeroi. The nematode was found in 10 of the 52 sampled sites; two localities corresponded to cave populations. The phylogenetic analysis based on COI sequences yielded three major lineages for P. (S.) neocaballeroi. We found no concordance between the three lineages and the habitat where they occur in Astyanax mexicanus, even considering those living in drastic environmental conditions (caves), or between these lineages and lacustrine ecomorphs of Astyanax aeneus and A. caballeroi occurring in sympatry. Instead, genetic lineages of the nematode exhibit a clearer pattern of host species association and geographical distribution; our results showed that P. (S.) neocaballeroi is experiencing an incipient divergence although the morphological study of lineages shows no conspicuous differences.
Utilisation of pharmacy-based sexual and reproductive health services: a quantitative retrospective study
Authors: Gauly Julia , Atherton Helen , Kimani Peter K , Ross Jonathan
Published: August 2020

Objectives

To explore the utilisation of pharmacy-based sexual and reproductive health services (SRHS) in order to optimise delivery and identify barriers to access.

Methods

The health provider Umbrella offers six SRHS from over 120 pharmacies in Birmingham (England). In this retrospective study, data collected between August 2015 and August 2018 were used to analyse uptake, user characteristics and attendance patterns according to day of the week.

Results

A total of 60 498 requests for a pharmacy service were included in the analysis. Emergency contraception (50.4%), condoms (33.1%) and STI self-sampling kits (9.6%) accounted for more than 90% of all requests. A lower uptake of services was observed for the contraceptive injection (0.6%), oral contraception (5.4%) and chlamydia treatment (1.0%). Services were most likely to be requested by those self-identifying as female (85.6%), and those aged 16–24 years (53.8%). Based on available ethnicity data (n=54 668), most requests for a service were made by White/White British individuals (43.4%) and Asian/Asian British people (23.1%). The largest number of services were delivered on Mondays (20.9%) and the lowest on Sundays (5.0%). A high proportion of requests for services on Saturdays (57.0%), Sundays (67.6%) and Mondays (54.4%) were made by females presenting for emergency contraception.

Conclusion

The evaluation of healthcare utilisation is important to help refine and optimise the delivery of services. However, information relating to pharmacy-based SRHS is scarce and often limited to a single type of service provision. Overall, a wide range of pharmacy-based services were accessed by a diverse range of people, suggesting that pharmacies are a suitable provider of many SRHS. However, the routinely collected data analysed in the study had several limitations restricting the analysis. Sexual health providers should ensure they collect data which are as comprehensive as is possible in order to help understand the utilisation of services.
Differences between exhausted CD8+ T cells in hepatocellular carcinoma patients with and without uremia
Authors: Xiaohong Chen , Jianzhou Zou , Bo Shen , Wenlv Lv , Xuesen Cao , Fangfang Xiang
Published: August 2020

The purpose of this study was to explore the differences between exhausted CD8+ T cells in hepatocellular carcinoma (HCC) patients with and without uremia. We enrolled 45 uremic patients who were recently diagnosed with HCC into the HCC + uremia cohort and similar patients with HCC but without uremia into the HCC-only cohort. Lymphocytes were obtained from the two cohorts, and exhausted CD8+ T cells, comprising PD-1+CD8+, TIM-3+CD8+, and LAG-3+CD8+ T cells, were sorted and expanded in vitro. After expansion, the proportions of PD-1+CD8+, TIM-3+CD8+, and LAG-3+CD8+ T cells were significantly higher in the HCC-only cohort than in the HCC + uremia cohort. CD8+ T cells expressing PD-1, TIM-3, or LAG-3 showed increased tumor reactivity and release of interferon-γ in vitro; however, these cells demonstrated weaker anti-tumor activity in HCC + uremia patients than in HCC-only patients. Among the expanded lymphocytes, only the decreased proportion of PD-1+CD8+ T cells significantly correlated with the HCC + uremia cohort (odds ratio of 2.731, p = 0.009). We concluded that peripheral CD8+ T cells expressing PD-1, TIM-3, or LAG-3 from the HCC + uremia cohort were dysfunctional in vitro. Among these populations, PD-1+CD8+ T cells were most evident in HCC patients with uremia.
Hypoxia-driven secretion of extracellular matrix proteins in the exosomes reflects the asymptomatic pathology of rotator cuff tendinopathies
Authors: Thankam Finosh G. , Agrawal Devendra K.
Published: August 2020

The major hallmark of rotator cuff tendinopathies (RCT) is the disorganization of the tendon extracellular matrix (ECM), which is due to a decrease in the ratio of collagen I to collagen III. In addition, the pathology of the tendon matrisome remains asymptomatic, and hypoxia has been identified to be the priming signal to initiate the molecular pathology of RCT. Also, the secretome content of hypoxia-challenged tendon cells (tenocytes) reflects the pathological status of RCT. With this background, the present study was designed to establish the expression status and molecular crosstalk of the ECM component proteins contained in the exosomes of the hypoxia-challenged swine tenocytes. The mass spectrometry analysis revealed the upregulation of COL1A2, P4HA1, PRDX2, P3H1, COL6A1, PPIB, LCN1, and COL3A1 and the downregulation of COLA12, PDIA4, COLG, FN1, CTSK, and TNC in the exosomes of hypoxic tenocytes. These proteins interact with diverse proteins and operate multiple pathways associated with ECM homeostasis and repair as determined by NetworkAnalyst. The functional analysis of these proteins reflects the pathology of tendon ECM, which is correlated with the asymptomatic phase of RCT. Understanding the signaling mediated by these proteins would reveal the underlying molecular pathology and offers translational significance in the diagnosis and management of RCT.
ASSESSING THE LINKAGES BETWEEN THE ELECTRICITY CONSUMPTION AND ECONOMIC FACTORS IN A LANDLOCKED ECONOMY: CASE STUDY OF LAO PDR
Authors: PANTHAMIT NISIT , CHAIBOONSRI CHUKIAT
Published: August 2020

This research paper aims to investigate linkages of electricity consumption representing energy security with estimated factors — GDP, population and foreign direct investment (FDI) during 1998–2018 for Laos People Democratic Republic (Lao PDR) by using ARDLbased Bayesian inference. This study provided empirical evidence on a long-run linear relationship analysis under ARDL-based Bayesian inference, which concludes that they have performed real relationships between electricity consumption, GDP, population and FDI. In addition, in the short-run, it was found that explanatory factors have both negative and positive impacts on Laos’ electricity consumption. The results confirm the hypothesis that although Lao PDR has access to domestic energy resources, only relying on one energy resource will make the energy system insecure. Thus, Lao PDR must develop substantial infrastructures and alternative renewable energies to support the campaign of Lao PDRs electricity security in the long-run.
COMPARING ECONOMETRIC ANALYSES WITH MACHINE LEARNING APPROACHES: A STUDY ON SINGAPORE PRIVATE PROPERTY MARKET
Authors: BIAN TINGBIN , CHEN JIN , FENG QU , LI JINGYI
Published: August 2020

We aim to compare econometric analyses with machine learning approaches in the context of Singapore private property market using transaction data covering the period of 1995–2018. A hedonic model is employed to quantify the premiums of important attributes and amenities, with a focus on the premium of distance to nearest Mass Rapid Transit (MRT) stations. In the meantime, an investigation using machine learning algorithms under three categories — LASSO, random forest and artificial neural networks is conducted in the same context with deeper insights on importance of determinants of property prices. The results suggest that the MRT distance premium is significant and moving 100[Formula: see text]m closer from the mean distance point to the nearest MRT station would increase the overall transacted price by about 15,000 Singapore dollars (SGD). Machine learning approaches generally achieve higher prediction accuracy and heterogeneous property age premium is suggested by LASSO. Using random forest algorithm, we find that property prices are mostly affected by key macroeconomic factors, such as the time of sale, as well as the size and floor level of property. Finally, an appraisal on different approaches is provided for researchers to utilize additional data sources and data-driven approaches to exploit potential causal effects in economic studies.
INTERNET FINANCE, NET INTEREST MARGIN AND NONINTEREST ACTIVITIES IN CHINA’S BANKING SECTOR
Authors: GUO PIN , CHENG MAOYONG , GAO ZHIXIAN
Published: August 2020

Using data from 133 Chinese commercial banks from 2003 to 2015, we examine the links among Internet finance, net interest margin and noninterest activities. Four main findings emerge. First, the net interest margin exerts significantly negative impacts on the noninterest activities through incentive distortion, cross-subsidization and resource restriction effects. The incentive distortion effect plays a stronger role, while the cross-subsidization and resource restriction effects play weaker roles. Second, Internet finance significantly promotes the development of noninterest activities, meaning that the technology spillover effect of Internet finance is stronger than the customer loss effect in China. Third, Internet finance strengthens the negative effects of the net interest margin on fee and commission activities but weakens the negative effects of the net interest margin on other noninterest activities. Finally, we find that the effects of the net interest margin on noninterest activities are stronger in state-owned banks than in non-state-owned banks, while the effects of Internet finance on noninterest activities are weaker in state-owned banks.
Hybrid Evolutionary Algorithm with an Optimal Sample Allocation Strategy for Multifidelity Simulation Optimization Problems
Authors: Chiu Chun-Chih , Lin James T.
Published: August 2020

Simulation has been applied to evaluate system performance even when the target system does not exist in practice. Dealing with model fidelity is required to apply simulation to practice. A high-fidelity (HF) simulation model is generally more accurate and requires more computational resources than a low-fidelity (LF) one. A low-fidelity model may have less accuracy than a HF one, but it can rapidly evaluate a design alternative. Consequently, the performance accuracy of the constructed simulation model and its computational cost involves a tradeoff.

In this research, the simulation optimization problem under a large design space, where a LF model may not be able to evaluate all design alternatives in the limited computational resource, is studied. We extended multifidelity (MF) optimization with ordinal transformation and optimal sampling (MO2TOS), which enables the use of LF models to search for a HF one efficiently, and proposed a combination of the genetic algorithm and MO2TOS. A novel optimal sample allocation strategy called MO2TOSAS was proposed to improve search efficiency. We applied the proposed methods to two experiments on MF function optimization and a simultaneous scheduling problem of machine and vehicles (SSPMV) in flexible manufacturing systems. In SSPMV, we developed three fidelity simulation models that capture important characteristics, including the preventive deadlock situation of vehicles and alternative machines. Simulation results show that the combination of more than one fidelity level of simulation models can improve search efficiency and reduce computational costs.
Bilinear forms and soliton solutions for a (2 + 1)-dimensional variable-coefficient nonlinear Schrödinger equation in an optical fiber
Authors: Wang Dong , Gao Yi-Tian , Su Jing-Jing , Ding Cui-Cui
Published: August 2020

In this paper, under investigation is a (2 + 1)-dimensional variable-coefficient nonlinear Schrödinger equation, which is introduced to the study of an optical fiber, where [Formula: see text] is the temporal variable, variable coefficients [Formula: see text] and [Formula: see text] are related to the group velocity dispersion, [Formula: see text] and [Formula: see text] represent the Kerr nonlinearity and linear term, respectively. Via the Hirota bilinear method, bilinear forms are obtained, and bright one-, two-, three- and N-soliton solutions as well as dark one- and two-soliton solutions are derived, where [Formula: see text] is a positive integer. Velocities and amplitudes of the bright/dark one solitons are obtained via the characteristic-line equations. With the graphical analysis, we investigate the influence of the variable coefficients on the propagation and interaction of the solitons. It is found that [Formula: see text] can only affect the phase shifts of the solitons, while [Formula: see text], [Formula: see text] and [Formula: see text] determine the amplitudes and velocities of the bright/dark solitons.
Revealing the strong and stable community structure in social networks
Authors: Zhang Xue , Luo Zhi-Hong , Wu Hui-Dong , Yang Zhuo-Xuan , Ma Pei-Yuan
Published: August 2020

In a complex network, the global similarity standard is of high complexity and local similarity standard has biased error on node similarity. This paper puts forward a community discovering algorithm OBS, based on the degree of contribution of shared nodes in complex network. It distributes the contribution, using the degree of shared nodes as the unit, equally, which is made by shared nodes. Compared with average commute time standard, Random Walk with Restart standard and Hierarchical Structure Method standard, OBS standard has a more veracious forecast to the similar relationship between nodes. The experimental results of artificial network and typical complex network show that OBS algorithm has a better stability than GN, Fast-Newman (FN), and N-cut algorithms.
Numerical exploration on drag and heat reduction mechanism of a spike-tipped supersonic blunt nose
Authors: Meng Yu-Shan , Yan Li , Li Shi-Bin , Huang Wei
Published: August 2020

In this study, the drag force and heat flux reduction mechanism induced by the aerodisk (with disks on its nose) with the freestream Mach number being 4.937 has been numerically investigated, and the simulations have been carried out by the three-dimensional Reynolds-averaged Navier–Stokes equations coupled with the SST [Formula: see text] turbulence model. The influence of the angle of attack on the drag and heat flux reduction has been analyzed comprehensively. The obtained results show that the drag force of the spiked blunt body can be reduced by the aerodisk, and the drag force decreases by 24.63%. The flow mechanism of the complex flow is drastically modified by the angle of attack, and this results in a strong flow asymmetry. This asymmetry becomes more and more obvious as the angle of attack increases. Both the pressure force and viscous force increase with the increase of the angle of attack. Moreover, both the lift and drag coefficients increase as the angle of attack increases, and the lift-to-drag ratio increases first and then decreases with the increase of the angle of attack. When the angle of attack is [Formula: see text], the maximum lift-to-drag ratio is close to 0.36.
The integrability of the coupled Ramani equation with binary Bell polynomials
Authors: Chai Xue-Dong , Li Chun-Xia
Published: August 2020

Binary Bell polynomial approach is applied to study the coupled Ramani equation, which is the generalization of the Ramani equation. Based on the concept of scale invariance, the coupled Ramani equation is written in terms of binary Bell polynomials of two dimensionless field variables, which leads to the bilinear coupled Ramani equation directly. As a consequence, the bilinear Bäcklund transformation, Lax pair and conservation laws are systematically constructed by virtue of binary Bell polynomials.
Research on electronic structure and optical characteristic of S-adsorbed 3C–SiC
Authors: Lu Xuefeng , Cui Zhihong , Guo Xin , Ren Junqiang , Xue Hongtao , Tang Fuling
Published: August 2020

An insight into electronic structure and optical feature of S-adsorbed 3C–SiC (111) surface is carried out employing first-principles calculation. It is found that the [Formula: see text] and B position systems with adsorption energies of 3.880 and 3.895, respectively, are relatively stable compared to the [Formula: see text] and C systems. Impurity energy levels are present near Fermi level in C and [Formula: see text] position adsorption systems and the band-gap decreases obviously in the two systems. A raindrop-like electron cloud of S atom can be observed in [Formula: see text] adsorption system and the order of the chemical bond strength in the adsorption system is [Formula: see text]. The B and [Formula: see text] adsorption systems have good light permeability in the visible and infrared regions, while the C and [Formula: see text] adsorption systems are relatively suitable as dielectric materials and have high service life when they as devices in the ultraviolet region.
Transmission control of acoustic metasurface with dumbbell-shaped double-split hollow sphere
Authors: Dong Yibao , Wang Yuanbo , Sun Jianxiang , Ding Changlin , Zhai Shilong , Zhao Xiaopeng
Published: August 2020

Complex structures, large size and limited manipulation of acoustic waves are the problems that restrict the development of acoustic metasurfaces. Here, we report a transmission-type acoustic metasurface based on local resonance mechanism, which is composed of meta-atomic units called dumbbell-shaped double-split hollow spheres (DSDSHS). This metasurface with subwavelength scale has the advantage of simple structure and easy preparation, and can realize the full manipulation of sound waves. Negative refraction with different transmission angles and high intensity plate focusing lens are realized in the air environment of audible frequency. The proposed metasurface has potential applications in the miniaturization and integration of sound transmission and sound energy collection, opening a new opportunity for manipulation of acoustic wavefront.
Eliminating the isolated states from the band structure of doped TiO2: A first principle study
Authors: Khan Matiullah , Yi Zeng
Published: August 2020

Band structure of anatase [Formula: see text] could be modified by doping foreign atoms. With ab-initio calculations, considering praseodymium, nitrogen and gadolinium as potential dopants, some mono-, co- and tri-doped models are introduced. The structure modification due to each model is compared with a standard [Formula: see text] system. Pr doping reduced the band gap of [Formula: see text] by introducing Pr 4f states below the conduction band, and the Fermi level appears below the conduction band minimum. The addition of nitrogen in Pr-doped [Formula: see text] pushed back the Fermi level to its intrinsic position while reducing the band gap. The tri-doped system comprising of Pr, N and Gd as dopants provided a populated band gap. The impurity states associated with Gd appeared in the middle of the band gap. The density of states analysis reveals that Pr 4f states change the location of N 2p states in the band structure. Instead of appearing as isolated states, the N 2p states are mixed with O 2p states while the Pr 4f states are coupled with the Ti 3d states in Pr, N-[Formula: see text]. The Pr, N, Gd tri-doped [Formula: see text] system provided strong visible light absorption due to the stepwise transition of electrons by Gd f states. While providing reasonable visible light absorption, the Pr, N-[Formula: see text] is expected to provide strong visible light photoactivity due to the clear band gap. Due to the absence of isolated states, the generated photo-excited carriers would be efficiently utilized in the oxidation/reduction processes.
Photothermoelectric resistance effect observed in Ti/SiO2/Si structure induced by 10.6 μm CO2 laser
Authors: Sun Xu , Zhu Pengfei , Zhu Kun , Ping Yunxia , Zhang Chaomin , Sun Xiaohui , Song Pei
Published: August 2020

A novel photothermoelectric resistance effect of the Ti/SiO2/Si films induced by 10.6 [Formula: see text]m CO2 laser is discovered and investigated. The transient response of the resistance is observed and analyzed in this work. Under the continuous irradiation of the laser, the thermal resistance value changes with the irradiating time and gradually reaches a stable saturation. The results indicate that the rise time of thermal resistance is shortened and its change rate increased as laser power gets higher. The inner battery of the ohmmeter exerts the positive or negative bias voltage, causing the diffusion motion direction of the hot electrons to be opposite or the same direction with the drift motion, which can increase or decrease the thermal resistance value. Those experimental phenomena are explained by the drift and diffusion motion of the electrons. Based on the results, the Ti/SiO2/Si structure is an attractive candidate for thermal effect devices.
Darboux transformation and exact solutions for a (2 + 1)-dimensional integrable system of nonlinear evolution equations
Authors: Zhou Zhen Chuan , Zhu Xiao Ming
Published: August 2020

In this paper, starting from a spectral problem, we construct a [Formula: see text]-dimensional integrable system of nonlinear evolution equations. Based on the Lax pair, the recursion operator and Darboux transformation for the whole hierarchy were constructed. As an application, some exact solutions for the hierarchy are obtained by using the Darboux transformation.
The cosmological constant of emergent spacetime in the Newtonian approximation
Authors: Castro-Palacio J. C. , Fernández de Córdoba P. , Isidro J. M.
Published: August 2020

We present a simple quantum-mechanical estimate of the cosmological constant of a Newtonian Universe. We first mimic the dynamics of a Newtonian spacetime by means of a nonrelativistic quantum mechanics for the matter contents of the Universe (baryonic and dark) within a fixed (i.e. nondynamical) Euclidean spacetime. Then we identify an operator that plays, on the matter states, a role analogous to that played by the cosmological constant. Finally, we prove that there exists a quantum state for the matter fields, in which the above-mentioned operator has an expectation value equal to the cosmological constant of the given Newtonian Universe.
Dirac equation with CPRS potential and Cornell tensor interaction in the presence of spin and pseudospin symmetry
Authors: Sedaghatnia Parisa , Hassanabadi Hassan , de Montigny Marc
Published: August 2020

Motivated by the prominent role of tensor interactions in nuclear spectroscopy and many applications of spin and pseudospin symmetry in hadronic and nuclear physics, we solve the Dirac equation with a CPRS potential and a Cornell tensor interaction, in the spin and pseudospin symmetry limits, by using the quasi-exactly solvable method. We obtain explicitly the wave functions for the two lowest energy levels, both for spin and pseudospin symmetry. We also discuss the degeneracy of the system.
NANOINDENTATION AND POROSITY FRACTAL DIMENSION OF CALCIUM CARBONATE WHISKER REINFORCED CEMENT PASTE AFTER ELEVATED TEMPERATURES (UP TO 900∘C)
Authors: LI LI , LI ZONGLI , CAO MINGLI , TANG YI , ZHANG ZHE
Published: August 2020

Calcium carbonate whisker (CW) can work as a cost-effective and environment friendly micro-fiber in reinforcing cementitious composites. Influence of high temperature on micro-structure of CW reinforced cement paste by nanoindentation and mercury intrusion porosimetry test is studied in this research. Up to 500[Formula: see text]C, the indentation depth, elasticity modulus, indentation hardness and interfacial transition zone (ITZ) width of CW reinforced cement paste are near or even better than that at room temperature, due to the coupling effect of CW transformation from aragonite to calcite and internal autoclaving. However, when the temperature is higher than 700[Formula: see text]C, nano-mechanical properties of CW reinforced cement paste degenerated significantly, due to the decomposition of CW and hydration products. Similarly, with the increase of temperature up to 400[Formula: see text]C, the porosity and pore size increase little or even decrease, while the fractal dimension of pore volume increases. With the introduction of CW, the pore parameters and fractal dimension are decreased up to 400[Formula: see text]C, due to the filler effect of CW. When the temperature is higher than 700[Formula: see text]C, the pore diameter and fractal dimension of CW reinforced cement paste are significant higher than that of pure cement paste, due to the decomposition of CW and hydration products. In CW reinforced cement paste, the fractal dimension was increased with the increased temperature and porosity in this research. There are negative correlations between the pore volume fractal dimensions and the strengths of CW reinforced cement paste. Fractal dimension is a useful tool to evaluate the change of pore structure at high temperature.
EXCELLENT ELECTROCATALYSIS OF OXYGEN EVOLUTION USING Co(OH)x(WO4)y/MESOPOROUS CARBON NANOCOMPOSITES
Authors: CAO PENGHUI , YAN YUHUA , TIAN XINLI , OUYANG RUIZHUO , MIAO YUQING
Published: August 2020

Oxygen evolution reaction (OER) is of great importance in splitting water. However, the sluggish OER kinetics at the anode severely hinders the H2 evolution at the cathode which is a crucial procedure for energy storage. Herein, we report the synthesis of a new OER catalyst of Co(OH)x(WO[Formula: see text] via a one-step hydrothermal method, where the incorporation of WO[Formula: see text] as a condenser greatly enhanced the electrocatalytic activity of Co(OH)2 toward OER. Moreover, the introduction of mesoporous carbon (MC) further improves the electrocatalytic performance of Co(OH)x(WO[Formula: see text] by forming the nanocomposites of Co(OH)x(WO[Formula: see text]/MC. The synergism between Co(OH)2 and WO[Formula: see text] and the synergistic catalytic effect of Co(OH)x(WO[Formula: see text] and MC majorly contributed to the apparently enhanced electrocatalysis of Co(OH)x(WO[Formula: see text]/MC toward OER. This work provides an efficient strategy to improve the electrocatalytic activity of Co(OH)2 by introducing WO[Formula: see text] and forming nanocomposites between Co(OH)x(WO[Formula: see text] and MC for low-cost, convenient and highly efficient water oxidation.
LASER SURFACE ALLOYING OF 304 STAINLESS STEEL WITH TUNGSTEN POWDER
Authors: DU BAOSHUAI , ZHANG ZHONGWEN , SUO SHUAI , LI XINMEI , DENG HUALING
Published: August 2020

Laser surface alloying was employed to enhance the wear resistance of 304 stainless steel with pure tungsten powder. The effect of laser fluence on phase constituents, microstructure, hardness and corrosion properties was investigated. It is found that the laser fluence has a direct correlation with the phases present in the coatings. Intermetallic Fe7W6phase was found in the composite coating due to the metallurgical reaction of W with the Fe, Cr and Ni elements in the melting pool. Coatings with composite microstructure in nature were obtained resulting from the dilution of substrate and the laser-induced rapid cooling process. Intermetallic phase of Fe7W6with solid solution of Ni and Cr shows dendrite or hallo structure depending on the laser fluence. Sintering and/or consolidation of W particles is observed for samples processed with lower laser fluences. It has been found that hardness of the coatings was improved significantly compared with the 304 stainless steel substrate. Coating processed with laser fluence of [Formula: see text] J/m2shows the best corrosion resistance.
INVESTIGATION OF NOISE CHARACTERIZATION OF COATED ROTORS
Authors: ÖZ ALİ , DEMİR ABDULLAH
Published: August 2020

In this study, four excessive worn brake rotors of a light commercial vehicle are coated using different thickness, methods and powder coatings. Coated rotors ([Formula: see text], [Formula: see text], [Formula: see text] and [Formula: see text]) compared with OEM brake rotor ([Formula: see text]0) in terms of friction coefficient ([Formula: see text]) and braking noise. Three braking test procedures (bedding, hot judder I and II) are applied to five rotors using inertia brake dynamometer. Results in bedding testing procedures showed that [Formula: see text] rotor provided higher brake noise and higher [Formula: see text] compared with coated rotors. In hot judder I testing procedures, [Formula: see text] rotor provided higher [Formula: see text] and higher brake noise compared with the other coated rotors and [Formula: see text]. Also, in hot judder II testing procedures, [Formula: see text] rotor provided higher [Formula: see text] compared with the other rotors, [Formula: see text] provided higher brake noise compared with the other coated rotors. In addition, based on experimental data, noise levels are estimated by multiple regression method with dummy variables.
CHEMICAL MECHANICAL POLISHING AND ITS MECHANISM ON YTTERBIUM-DOPED MIXED SESQUIOXIDES (Yb:LuScO3)
Authors: FANG YUANYUAN , HE HONGBO , WU LUNZHE , WANG ZHE , DUN AIHUAN , ZHANG LONG
Published: August 2020

In this paper, Yb:LuScO3 crystal was processed by chemical mechanical polishing (CMP), and the surface roughness of 0.18[Formula: see text]nm was obtained. The atomic step structures of these sesquioxide crystals are successfully characterized by AFM scanning probe technology. Through several CMP experiments, the basic material removal mechanism of a ytterbium-doped LuScO3 crystal during CMP is studied. Based on the findings, a material removal model is established. The results of this study provide ideas for the study of CMP, crystal growth and epitaxy.
The Evolving Basis for the Design of Light Gauge Steel Systems
Authors: Kyvelou Pinelopi , Nethercot David A. , Hadjipantelis Nicolas , Kyprianou Constantinos , Gardner Leroy
Published: August 2020

The importance of allowing for the many different types of structural interaction that have an effect on the performance of light gauge members when used in practical situations is emphasized. A distinction is drawn between internal interactions involving the various plate elements of the steel profiles and external interactions involving the other components in the system. Although full-scale testing of representative systems can capture this behavior, the costs involved make this an impractical general basis for design; codified methods generally consider only isolated plates within members and isolated members within systems, thereby neglecting the potentially beneficial effects of both forms of interaction. Properly used, modern methods of numerical analysis offer the potential to systematically allow for both forms of interaction — provided the numerical models used have been adequately validated against suitable tests. The use of such an approach is explained and illustrated for three commonly used structural systems: roof purlins, floor beams, and columns in stud walls. In each case, it is shown that, provided sufficient care is taken, the numerical approach can yield accurate predictions of the observed test behavior. The subsequently generated large portfolio of numerical results can then provide clear insights into the exact nature of the various interactions and, thus, form the basis for more realistic design approaches that are both more accurate in their predictions and which lead to more economic designs. Building on this, modifying existing arrangements so as to yield superior performance through specific modifications is now possible. Two such examples, one in which improved interconnection between the components in a system is investigated and a second in which prestressing is shown to provide substantial enhancement for relatively small and simple changes, are presented.
Bridge Surface Roughness Identified from the Displacement Influence Lines of the Contact Points by Two Connected Vehicles
Authors: Yang Y. B. , Wang B. Q. , Wang Z. L. , Shi K. , Xu H. , Zhang B. , Wu Y. T.
Published: August 2020

In this study, a new, effective procedure is proposed for identifying the surface roughness from the responses recorded of two connected test vehicles moving over the bridge. Central to this study is the proposal of a simple static correlation formula for relating the dynamic deflections of the two vehicles’s contact points on the bridge, via the displacement influence lines (DILs). With the aid of this relation, the roughness formula for estimating the bridge surface profile is derived using the responses of the leading and following vehicles. It does not require any prior knowledge of the dynamic properties of the bridge. The efficacy of the proposed procedure is validated for both the simple and three-span continuous beams by the finite element method (FEM). Also, a parametric study is conducted for various physical properties of the test vehicles. It is confirmed that the roughness profiles back-calculated from the proposed formula agree excellently with the assumed ones for both the simple and continuous beams. For use in practice, the two connected test vehicles should not be designed too heavy and not to move at too fast speeds, in order to reduce the impact on the bridge.
The Duffing-Holmes Oscillator Under Hybrid Position Feedback Controller: Response Type and Basin of Attraction Analyses
Authors: Simsek Mehmet R. , Bilgen Onur
Published: August 2020

This paper presents a detailed response type and basin of attraction (BOA) analyses of a linear mass-spring-damper oscillator and a Duffing-Holmes (D-H) oscillator controlled by a class of position feedback controllers. First, the response-type comparison of both linear and D-H systems subjected to a, Negative Position Feedback (NPF), and Positive Position Feedback (PPF) controllers, and Hybrid Position Feedback (HPF) controller (which combines the previous two) is analyzed individually. Initially, the bistable system is expressed as two linear models around the stable equilibriums, and shows similar dynamic characteristics near the vicinity of stable equilibria. Three relevant response types are identified for the controlled D-H oscillator. These are the intra-well, single cross-well, and multiple cross-well response types describing all possible responses. With the BOA analyses, three response convergence types are defined. These are the convergence to state-1, convergence to state-2, and no convergence. The overall behavior of the bistable system under the hybrid controller is examined and described using these response- and convergence-type analyses. In this paper, it is shown that the HPF control concept provides desirable response for a wider range of systems and initial conditions when compared to the other simpler control schemes. The range of desirable controller parameters is identified.
π-Rickart and dual π-Rickart objects in abelian categories
Authors: Crivei Septimiu , Olteanu Gabriela
Published: August 2020

We introduce and study (strongly) [Formula: see text]-Rickart objects and their duals in abelian categories, which generalize (strongly) self-Rickart objects and their duals. We establish general properties of such objects, we analyze their behavior with respect to coproducts, and we study classes all of whose objects are (strongly) [Formula: see text]-Rickart. We derive consequences for module and comodule categories.
Spatial estimates for Kelvin–Voigt finite elasticity with nonlinear viscosity: Well behaved solutions in space
Authors: Quintanilla Ramon , Saccomandi Giuseppe
Published: August 2020

We provide some spatial estimates for the nonlinear partial differential equation governing anti-plane motions in a nonlinear viscoelastic theory of Kelvin–Voigt type when the viscosity is a function of the strain rate. The spatial estimates we prove are an alternative of Phragmen–Lindelöf type. These estimates are possible when a precise balance between the elastic and viscoelastic nonlinearities holds.