bluuebunny/crossref_metadata_2025 huggingface dataset:
Removal and recovery of SO2 and NO in oxy-fuel combustion flue gas by calcium-based slurry
Authors: Cai Yuyang , Ding Xiaohan , Li Wei , Liu Dunyu , Chen Jun , Ni Mingguo , Xu Kailong , Jin Jing
Published: October 2020

This study investigates the use of calcium-based slurry for simultaneous removal NO and SO2 from oxy-fuel combustion flue gas, and recovery of the sulfur and nitrogen species in resulting solutions. The experiments were performed in a bubbling reactor in a transient mode under the pressure of 20 bar. The various influencing factors including the CaO amount, carrier gas (N2/CO2), and absorption time on the simultaneous NO and SO2 removal process, and the solution products were studied comprehensively. The results show that the NO2 removal efficiency can be improved by the presence of CO2, and the gas phase HNO2 produces in this process. The addition of CaO has positive effects not only on the NO2 removal efficiency but also on the formation of stable HNO3. With the presence of CO2, CaCO3 is formed in a solution initially. With the decrease of pH, CaCO3 is gradually converted to CaSO4, and in particular CaCO3 can be fully avoided through decreasing the pH of an absorption solution to 1.14. At the same time, the formation of unstable S(IV) and NO2- can be prevented when the solution pH is lower than 1.37. The nitrogen and sulfur compounds in the absorption solution (at pH 1.14) were further separated by the addition of different amounts of CaO. In particular, 95% of SO42- finally can be recovered in the form of CaSO4.2H2O with nitrogen in solution existing as NO3- by controlling the Ca/S ratio at 4.70. The effectiveness of calcium-based slurry on the removal and recovery of SO2 and NO is confirmed.
Simple static hydroponic technology of Chenopodium quinoa Willd
Authors: Fu Rongxia , Yang Ming , Zhou Xueyong , Zhao Cong , Cui Yan
Published: October 2020

As a new type of “foreign vegetable”, Chenopodium quinoa Willd vegetable is delicious and nutritious. However, the field cultivation of quinoa is affected by the soil, temperature and precipitation. At the present study, a simple static hydroponics method for quinoa cultivation was investigated. The results showed that both fresh weight and dry weight of Chenopodium quinoa Willd vegetable increased rapidly during the growth period of 18-28 days, and after 28 days, the increase rate became slow. The plant height of quinoa ranged from 12.55+1.77 cm to 23.91 +2.54 cm between 18 and 38 days. The static hydroponics provided an alternative method for quinoa cultivation.
Identification and Interpretation of fan deposits in Block H12 of Beixi subsag, Beier depression, Hailar basin
Authors: Yu-lin QI , Yue ZHOU
Published: October 2020

Fan deposits in the Nantun formation in Beier depression have been drilled in the past two decades. It’s difficult to identify and describe subtle traps formed by fans by seismic interpretation. By using a combination of seismic interpretation techniques on the workstation, most of these traps can be identified. By high resolution seismic synthesis records, it is clear to know that the location of the fan body on the seismic profile, and its property. Because of multi-layered and uneven thickness, it is impossible to delineate fan delta features in Nantun formation by one single seismic attribute, Multi-attribute analysis can extend resolution of the seismic data, improve visualization of layer internal composition, see your sand bodies delineation more clearly. Seismic inversion using high resolution log curves and borehole data as a guide can get reservoir thickness. 3d visualization of automatic tracking results makes the reservoir more intuitive. Based on the stratum seismic interpretation, using seismic attribute analysis can depict the shape of the fan, using wave impedance inversion can predict the thickness of the fan, and using automatic tracking technology can display the whole fan.
Mining Ground Surface Information Extraction and Topographic Analysis Using UAV Video Data
Authors: Yaqiu Yin , Cunhao Jiang , Jing Lv , Jie Wang , Xing Ju , Hao Wang , Yu Xing , Lushou Zhang
Published: October 2020

Taking the Xiangwang bauxite mining of Xiaoyi City, Shanxi Province as the research object, the DJi “Wu”inspire2 model Unmanned aerial vehicle (UAV) was used to obtain the video data, image data and Ground control points (GCP) data of a typical pit in the study area. Based on the two kinds of data source (video data and image data), the Digital surface model (DSM) of the research area was acquired with or without ground control points through aerial triangulation and block adjustment. Using the DSM obtained by the two data source, the distribution of elevation, slope, slope direction, surface fluctuation and surface roughness was extracted and compared. Research shows that the DSM, acquired by the ContextCapture software without GCP, using video data obtained by aerial shooting around one interest point, can qualitatively reflect the topographic distribution of the land surface. The DSM got by the video data with the GCP can achieve the similar accuracy with the result obtained by image data, and the topographic information acquired by the two kinds of data source has highly similar characteristics in spatial and numerical distribution. It can be concluded through comparison and analysis of the topographical factors that steep slopes with complex topography and large elevation difference distributes in the northwest-central of the pit, of which northwest and southwest slopes can be easily eroded by wind and rain, so attention should be paid to slop stability monitoring and disaster prevention in this area. As a whole, the results show that video data obtained by UAV can not only reflect the dynamic changes of the land surface qualitatively, but also can describe the distribution of surface topography quantitatively through processing to get the DSM. It has great application potential in the field of disaster emergency monitoring and geological hazard risk assessment in mining areas.
Humic substances and its electron transfer capacity during composting: A review
Authors: Dai Yu , Lu Yu-lan , Li Jun , Qin Hai-guang , Xia Fei-yang , Zhang Jun
Published: October 2020

Humic substances (HS) are important product during composting, which play a key role in the maturity of compost, and its electron transfer characteristics have significant applications in the reduction of pollutants. We focus on the structure and composition characteristics and formation mechanism of HS during the composting. The effects of composting raw materials, additives, microorganisms and oxygen supply conditions on the formation of HS were reviewed. The electron transfer mechanism of compost HS was summarized as well as the structural and environmental factors affect the electron transfer of HS. The applications of HS in soil pollution control and water treatment are introduced. The research directions of HS formation mechanism, electron transfer mechanism and its application are also prospected.
Urban Wetland Restoration Design Based on the Ecological Concepts--Taking Guanyintang Wetland Park in Chongqing as an Example
Authors: Zhang Qing , Tian Weiran , Huang Ying
Published: October 2020

With the improvement of people’s awareness of environmental protection and the pursuit of high standards of living places, there are more thinkings about urban ecological issues. Through the construction of urban wetland parks, it is of great significance to improve the appearance of the city and maintain the urban ecological balance and sustainable ecological development. Taking Guanyintang Wetland Park in Chongqing as an example, low-lying swamps are used to build wetland parks. Guided by ecological theory, make full use of the original site conditions to restore the design of the wetland park, optimize the ecological functions of the area, and increase the recreation of tourists places, elaborately create an urban environment with perfect functions, beautiful ecology, livable and industrial, so as to further enhance the city’s taste.
Requirements for enterprise information disclosure on green and low-carbon
Authors: Zong Jianfang , Li Pengcheng , Chen Lili , Sun Liang , Liu Meng , Ding Qing , Guan Jinxin
Published: October 2020

As an important bridge for communication between the enterprise and the stakeholders, the corporate information disclosure on green and low-carbon draws more and more attention. This paper has introduced the basic principles for corporate information disclosure on green and low-carbon, and has researched the green and low-carbon related international standards, and information disclosure on green and low-carbon of domestic and foreign enterprises. On that basis, this paper has expounded the main contents of corporate information disclosure on green and low-carbon and disclosure implementation.
Mapping Regional Ecosystem Functional Types Based on Sentinel-2 Satellite Imagery
Authors: Liu Rong , Huang Fang , Ren Yue
Published: October 2020

Ecosystem functional types (EFTs) are the patches of land surface showing similar in carbon dynamics. EFTs are not defined by the structure and composition of vegetation and represent the spatial heterogeneity of ecosystem functions. Identifying EFTs based on low-resolution satellite remote sensing data cannot satisfy the needs of fine-scale characterization of regional ecosystem functional patterns. Here, taking Zhenlai County, Northeast China as an example, the heterogeneity in ecosystem functions was characterized by identifying EFTs from Sentinel-2 time series data using ISODATA algorithm. Ecosystem functional attributes derived from dynamics of the normalized difference vegetation index (NDVI), the fraction of absorbed photosynthetically active radiation (FAPAR), and canopy water content (CWC) in the growing season were calculated. The correspondence analysis (CA) method was used to reveal relationships between the EFTs and land cover types. Our results showed that the nine selected remotely sensed variables indicating carbon and water flux of the regional ecosystems could be adopted in ecosystem functions classification. The obtained EFTs based on Sentinel-2 images reflected the internal structure of carbon balance well and the distribution pattern of ecosystem functional diversity a fine scale. This study helps to understand the functional heterogeneity pattern of temperate terrestrial ecosystems.
The Regional Characteristics and Development of Plant Landscape Construction in Sichuan Garden
Authors: Tang Shilan , Liang Jinghui
Published: October 2020

Sichuan garden is one of the important regional schools in Chinese classical gardens. The construction of plant landscape in Sichuan gardens show obvious regional characteristics. By sorting out the types of the Sichuan gardens, this paper selects the representative classical gardens and modern gardens in Sichuan area as research cases to study plant landscape construction. From the perspective of landscape architecture and urban natural ecological environment, this paper summarizes the regional characteristics of Sichuan gardens in the construction of plant landscape, and explores the role of Sichuan regional plant landscape construction in displaying the local regional culture, improving the quality of life of urban residents, the urban living environment and urban ecological environment. Taking Du Fu Thatched Cottage, Qingyang Palace, Wenshu Temple and Living-water Garden in Chengdu as examples, this paper analyses the regional construction methods of plant landscape in Sichuan gardens, summarizes the regional characteristics of plant landscape construction in Sichuan gardens, in order to provide reference for the improvement of urban ecological environment.
Damage assessment of infrastructure based on urban flood inundation simulation
Authors: Yifan Zhu , Ping Yu , Peng Wang
Published: October 2020

Flood is a serious challenge that increasingly produce immense economical and ecological damages in worldwide. Flood simulation is gradually becoming a central focus of the hydrology in recent years. It is worthwhile to combine flood simulation with flood damage to infrastructure. The purpose of this study is to develop an approach for better urabn flood simulation at different return periods and assess the damage of flood to infrastructures in different return period. The approach is organized into four parts: design rainstorm event simulation, runoff simulation, flood inundation simulation and submerged infrastructures extraction. Base on the flood simulation, we draw the flood inundation map of Xuanwu-Qinhuai-Jianye-Gulou-Yuhuatai (XQJGY) region. Results indicated that the transportation infrastructures suffer the largest proportion of flood damage. This study simulates the inundated infrastructure at different return periods, provides a theoretical support for flood risk management.
Nonlinear plasmonic metasurfaces assisted laser mode locking
Authors: Zhang Lei , Wang Jiyong , Coillet Aurelien , Grelu Philippe , Cluzel Benoit , Qiu Min
Published: October 2020

Plasmonic metasurfaces are artificial 2D layers made of subwavelength elementary cells, which give rise to novel wave properties that do not exist in nature. In the linear regime, their applications have been extensively studied, especially in wavefront manipulation for lensing, holography or polarization control. Interests in metasurfaces operating in nonlinear regime have also increased due to their ability to efficiently convert the fundamental light into harmonic frequencies and multiphoton emissions. Nevertheless, practical applications in the nonlinear regime have been rarely reported.

In this study, we report that plasmonic metasurfaces with well-controlled polarimetric nonlinear transfer functions perform as saturable absorbers with modulation performances superior to that of other 2D materials. We employ planar nanotechnologies to fabricate 2D plasmonic metasurfaces with precise size, gap and orientation. We quantify the relationship between saturable absorption and the plasmonic resonances of the unit cell by altering the excitation power of pumping laser, the polarization of incident light and the geometrical parameters of the plasmonic metasurfaces. Finally, we provide a practical implementation by integrating the saturable metasurfaces into a fiber laser cavity and realize a stable self-starting ultrashort laser pulse generation. As such, this work sheds light on ultrathin nonlinear saturable absorbers for applications where nonlinear functions are required, such as in ultrafast laser or neuromorphic circuits.
The Driving Forces of Human Society Main Transitions
Authors: Lévy Jean-Claude Serge
Published: October 2020

The four main steps of human evolution: hunting-gathering, farming-livestock herding, industrial era and conception era are considered here as distinct phases parted by dynamic phase transitions. Comparing these social phases enables us to deduce the driving forces occurring during these transitions. At each transition the laymen lost some previous advantages, these losses had to be balanced by some counterweights, the transition driving forces. For instance, the first transition is shown to result from an equilibrium between efficiency and power, social partition and religion. Other transitions are similarly analysed with evidence for driving forces leading to deep social reconstructions.
The Comminges County from the 10th to the 15th century
Authors: Casanova Maryse , Brousse Jean-Louis
Published: October 2020

From the 10th to the 15th centuries, the counts of Comminges developed their important domain and resisted the ambitions of their powerful neighbors. Alliances, treaties, marriages, wars, everything has been good to preserve their goods. These counts played happily with their personalities, their strengths, their weaknesses, their malice. They supported the economic and social development. The population gradually migrated from the mountains to the plain, first with the help of the Church and the creation of the “sauvetés”. Then the liberality of the counts allowed the construction of numerous “bastides” in the 13th century. The county families provided the majority of the Commingeois bishops and reinforced the importance of the Secular Church. By their permanent support to the Regular Church, they favored the establishment of large monastic and templar domains, the development of as much farming land. The progressive close up with the raimondine city of Toulouse, placed the County under his protection after the crusade by the Albigensians in 1218. The war against the English, the devastations of the Black prince in 1355 opened the last page of this story, accompanied by calamities that left in 1453 a bloodless Comminges in the hands of the King of France.
Space-time registration-based model reduction of parameterized one-dimensional hyperbolic PDEs
Authors: Taddei Tommaso , Zhang Lei
Published: October 2020

We propose a model reduction procedure for rapid and reliable solution of parameterized hyperbolic partial differential equations. Due to the presence of parameter-dependent shock waves and contact discontinuities, these problems are extremely challenging for traditional model reduction approaches based on linear approximation spaces. The main ingredients of the proposed approach are (i) an adaptive space-time registration-based data compression procedure to align local features in a fixed reference domain, (ii) a space-time Petrov–Galerkin (minimum residual) formulation for the computation of the mapped solution, and (iii) a hyper-reduction procedure to speed up online computations. We present numerical results for a Burgers model problem and a shallow water model problem, to empirically demonstrate the potential of the method.
Hemodynamic Changes in Response to Aerobic Exercise: Near-infrared
Spectroscopy Study
Authors: Kim Hee Jin , Bae Sujin , Huh Jung Hun , Lee Jea Woog , Han Doug Hyun
Published: October 2020

This study aimed to determine the neurophysiological mechanisms underlying
the effects of aerobic exercise, which influence brain O2 consumption, on
cognitive enhancement. Sixteen healthy men were asked to complete a 2-back
test at rest and after moderate and high-intensity aerobic exercise. During
the 2-back test, hemodynamic changes within the prefrontal cortex were
assessed using high-density functional near-infrared spectroscopy. Scores of
the 2-back test, regardless of the exercise intensity, were positively
correlated with the hemodynamic changes within the right and left
dorsolateral prefrontal cortex (DLPFC). During an 2-back test, there were
differences in the hemodynamic changes within the DLPFC with moderate and
high-intensity exercise conditions. In the 2-back condition, the accumulated
oxyhemoglobin within the right DLPFC after moderate intensity exercise was
7.9% lower than that at baseline, while the accumulated
oxyhemoglobin within the left DLPFC was 14.6% higher than that at
baseline after high-intensity exercise. In response to the 2-back test, the
accumulated oxygenated hemoglobin within the left DLPFC after high-intensity
exercise increased more significantly than that observed after moderate
intensity exercise. These results show that the right DLPFC consumes O2 more
efficiently in response to moderate intensity aerobic exercise than in
response to high-intensity aerobic exercise.
Childhood Uveitis
Authors: Thurau Stephan
Published: October 2020

Childhood uveitis is an ophthalmological challenge, since on the one hand it often remains asymptomatic and difficult to detect, and on the other hand it often has a chronic course and is associated with a high risk of complications threatening the vision. The most important risk factors for childhood uveitis are underlying rheumatic diseases; recommendations for ophthalmological monitoring have been developed together with paediatric rheumatologists. Intermediate and posterior uveitis are rare in children. The therapy must effectively control inflammation and at the same time cause only minimal side effects. Since steroids in particular cause side effects frequently, an immunosuppressive therapy must be initiated early in an interdisciplinary cooperation with paediatric rheumatologists and parents with the goal of minimising steroids.
Diiodine–Triethylsilane System: Reduction of N-Sulfonyl Aldimines to N-Alkylsulfonamides
Authors: Jiang Jin , Xiao Lili , Li Yu-Long
Published: October 2020

Because molecular iodine and hydrosilanes are stable to both air and moisture, reactions using these reagents are easy to operate and require mild reaction conditions. Molecular iodine and a hydrosilane were used to reduce N-sulfonyl aldimines to the corresponding N-alkylsulfonamides. This transformation is a practical method for the synthesis of N-alkylsulfonamides.
Palladium(II)-Catalyzed Three-Component Tandem Cyclization Reaction for the One-Pot Assembly of 4-Arylquinazolines
Authors: Zhang Guolin , Yu Yongping , Wang Zijuan , Chen Wenteng , He Chang
Published: October 2020

A one-pot method for joining three separate components leading to an assortment of 4-arylquinazolines (27 examples) in good to excellent yields is described. The method consists of a palladium(II)-catalyzed­ cascade reaction involving C(sp)–C(sp2) coupling followed by intramolecular C–N bond formation. The reaction was readily scaled up to gram quantity and successfully applied to the synthesis of a translocator­ protein (TSPO) ligand.
Management of Orthostatic Hypotension, Postprandial Hypotension, and Supine Hypertension
Authors: Shibao Cyndya A. , Biaggioni Italo
Published: October 2020

This review provides recommendations for the treatment of neurogenic orthostatic hypotension (nOH), postprandial hypotension, and supine hypertension. It focuses on novel treatment strategies and new insights into the mechanism underlying these conditions. Our goal is to provide practical advice for clinicians on how to screen, diagnose, and treat these conditions with nonpharmacological and pharmacological approaches. For each disorder, we offered a stepwise recommendation on how to apply these new concepts to successfully ameliorate the symptoms associated with OH to prevent syncope and falls. The management of OH in patients who also have supine hypertension requires special considerations and pharmacotherapy. It is noteworthy that there are few therapeutic options for OH and only two Food and Drug Administration–approved drugs for the treatment of OH and nOH based on randomized clinical trials. We will use these studies to develop evidence-based guidelines for OH. The research is limited for postprandial hypotension and supine hypertension, and therefore the recommendations will be based on small studies, clinical expertise, and, above all, an understanding of the underlying pathophysiology.
Patient-Initiated Data: Our Experience with Enabling Patients to Initiate Incorporation of Heart Rate Data into the Electronic Health Record
Authors: Pevnick Joshua M. , Elad Yaron , Masson Lisa M. , Riggs Richard V. , Duncan Ray G.
Published: October 2020

Background Provider organizations increasingly allow incorporation of patient-generated data into electronic health records (EHRs). In 2015, we began allowing patients to upload data to our EHR without physician orders, which we henceforth call patient-initiated data (PAIDA). Syncing wearable heart rate monitors to our EHR allows for uploading of thousands of heart rates per patient per week, including many abnormally low and high rates. Physician informaticists expressed concern that physicians and their patients might be unaware of abnormal heart rates, including those caused by treatable pathology.

Objective This study aimed to develop a protocol to address millions of unreviewed heart rates.

Methods As a quality improvement initiative, we assembled a physician informaticist team to meet monthly for review of abnormally low and high heart rates. By incorporating other data already present in the EHR, lessons learned from reviewing records over time, and from contacting physicians, we iteratively refined our protocol.

Results We developed (1) a heart rate visualization dashboard to identify concerning heart rates; (2) experience regarding which combinations of heart rates and EHR data were most clinically worrisome, as opposed to representing artifact; (3) a protocol whereby only concerning heart rates would trigger a cardiologist review revealing protected health information; and (4) a generalizable framework for addressing other PAIDA.

Conclusion We expect most PAIDA to eventually require systematic integration and oversight. Our governance framework can help guide future efforts, especially for cases with large amounts of data and where abnormal values may represent concerning but treatable pathology.
Real-time signal processing in field programmable gate array based digital gamma-ray spectrometer
Authors: Liu Yinyu , Xiong Hao , Dong Chunhui , Zhao Chaoyang , Zhou Quanfeng , Li Shun
Published: October 2020

Field programmable gate arrays (FPGAs) are attractive for a digital spectrometer due to its advantages of digital signal processing. However, how to improve the versatility of the spectrometer and increase the operating frequency of the digital shaper has gradually become a limitation that needs to be resolved in the FPGA-based spectrometer. A solution to improve the universality of the FPGA-based digital spectroscopy system is presented in this work, and the implementation of the real-time digital signal processing unit is improved to obtain a higher operating frequency, and then the optimal parameters of the digital trapezoidal shaper and the processing unit are also discussed through a series of experiments; finally, a FPGA-based digital spectrometer is developed. With the HPGe detector, the spectrometer achieves excellent energy resolution performance of 0.35% at 662 keV, 0.25% at 1173.2 keV, and 0.23% at 1332.5 keV.
Shunting the electric arc helical spiral turns (numerical simulation)
Authors: Urusov R. M. , Urusova I. R.
Published: October 2020

A numerical simulation was performed for an open direct current (dc) electric arc in a uniform external axial magnetic field. The calculation was carried out in the frameworks of a non-stationary three-dimensional mathematical model in approximation of partial local thermodynamic equilibrium of plasma. The model does not presuppose a helical shape of the arc, as is customary in theoretical studies based on linear perturbation theory. It was shown that the helical shape of an open arc is not constant in time and periodically collapses with subsequent restoration. In a certain range of external parameters of the arc (current strength, inter-electrode distance, and external axial magnetic field), a new mode of destruction of a regular structure was revealed – the arc section shunting between the spiral turns. Shunting can be single or double when the breakdown occurs simultaneously in two places. Apparently, it is caused by convective heat transfer by plasma flows as well as by the sliding of the arc thermal field. The appeared thermal field creates a zone of electric conductivity in which the breakdown occurs.
Switch effect for spin-valley electrons in monolayer WSe2 structures subjected to optical field and Fermi velocity barrier
Authors: Hao X.-J. , Yuan R.-Y. , Ji T. , Guo Y.
Published: October 2020

To investigate the effects of the optical field and the Fermi velocity on the transport properties of spin and valley electrons, we impose a normal/ferromagnetic/normal (N/F/N) quantum structure based on the monolayer WSe2. The results indicate that there is a strong switch effect for spin- and valley-related electrons. When left-handed off-resonant circularly polarized light is irradiated in the intermediate ferromagnetic region, 100% polarization for K valley electrons can be achieved in the entire effective energy spectrum of the optical field. Meanwhile, 100% polarization of the K′ valley can also be gained with the right-handed off-resonant circularly polarized light in the junction. Moreover, the perfect polarization of spin-up electrons can be obtained when the ferromagnetic exchange field is applied to the structure. Additionally, the Fermi velocity barrier also changes the energy band of the studied material, which makes the spin and valley transport increase with the increase of the velocity barrier but does not produce spin or valley polarizations. These interesting results clarify that the optical field and the Fermi velocity both make a contribution to the modulation of spin electrons for the two valleys and provide a useful method for the design of novel spintronic and valleytronic devices.
Training atomic neural networks using fragment-based data generated in virtual reality
Authors: Amabilino Silvia , Bratholm Lars A. , Bennie Simon J. , O’Connor Michael B. , Glowacki David R.
Published: October 2020

The ability to understand and engineer molecular structures relies on having accurate descriptions of the energy as a function of atomic coordinates. Here, we outline a new paradigm for deriving energy functions of hyperdimensional molecular systems, which involves generating data for low-dimensional systems in virtual reality (VR) to then efficiently train atomic neural networks (ANNs). This generates high-quality data for specific areas of interest within the hyperdimensional space that characterizes a molecule’s potential energy surface (PES). We demonstrate the utility of this approach by gathering data within VR to train ANNs on chemical reactions involving fewer than eight heavy atoms. This strategy enables us to predict the energies of much higher-dimensional systems, e.g., containing nearly 100 atoms. Training on datasets containing only 15k geometries, this approach generates mean absolute errors around 2 kcal mol−1. This represents one of the first times that an ANN-PES for a large reactive radical has been generated using such a small dataset. Our results suggest that VR enables the intelligent curation of high-quality data, which accelerates the learning process.
Comparative ab initio study of the structural, electronic, dynamical, and optical properties of group-I based CuMO2 (M = H, Li, Na, K, Rb)
Authors: Upadhyay Deepak , Joshi Nikunj , Pratap Arun , Jha Prafulla K.
Published: October 2020

Despite similar chemical compositions, the CuMO2 (M = H, Li, Na, K, Rb) compounds show remarkably distinct structural, electronic, dynamical, and optical properties. Different alkali atoms have a significant influence on their electronic, dynamical, and optical behavior. By means of first principles based density functional theory calculations, we explore the universality of electronic characteristics, dynamical stability, and optical properties of these compounds. The electronic band structures, vibrational frequencies, and optical properties are deeply connected with the atomic radius of the alkali atoms. The electronic bandgap of CuMO2 (M = H, Li, Na, K, Rb) lies within the range of 0.5–1.0 eV bringing them in the group of low bandgap p-type semiconductors. We found a significant increase in the bandgap and p–d hybridization as going from H to Rb. Partial density of states revealed strong metal–oxygen (Cu–O) overlap due to the strong p–d hybridization. The phonon dispersion curves obtained for these compounds confirm the dynamical stability as there is no imaginary frequency throughout the Brillouin zone. The static dielectric constants and refractive index fall within the range of 8.0–12.91 and 1.98–3.55, respectively, suggesting the usefulness of scrutinized compounds in non-linear optical devices. The optical properties depict that the alkali atoms based delafossites can serve as promising candidates for highly efficient optical devices within a broad range from visible to ultraviolet light of electromagnetic spectra.
Giant enhancing photoresponse at LaAlO3/SrTiO3 interfaces by the nickelate buffer layer
Authors: Yang Ruishu , Bi Cong , Zhao Shenggui , Li Ming , Asad Iqbal. Muhammad , Khalid Butt Mehwish , Jin Kexin
Published: October 2020

Manipulating the photoresponse of two-dimensional electron gas at the interface of complex oxides is attracting tremendous interest because of its potential applications in photoelectric devices. In this study, transport behaviors of LaAlO3/SrTiO3 heterointerfaces tuned by a nickelate buffer layer under light irradiation have been investigated. With the increasing thickness of the buffer layer, the LaAlO3/SrTiO3 interfaces exhibit the metal-to-insulator transition. More importantly, we also observe a substantial enhancement in the photoresponse under a 360 nm light irradiation and the relative change in the resistance of heterointerfaces is enhanced from 6.8% (without a buffer layer) to 50 139% (with a 1.6 u.c. buffer layer) at 300 K. Moreover, the heterointerfaces exhibit a state of change from persistent to transient photoconductivity. These emerging results are analyzed in view of the relevant mechanisms of band bending and lattice effects. This work provides experimental support for the application of perovskite oxides in interface optoelectronics.
Peptide Gaussian accelerated molecular dynamics (Pep-GaMD): Enhanced sampling and free energy and kinetics calculations of peptide binding
Authors: Wang Jinan , Miao Yinglong
Published: October 2020

Peptides mediate up to 40% of known protein–protein interactions in higher eukaryotes and play an important role in cellular signaling. However, it is challenging to simulate both binding and unbinding of peptides and calculate peptide binding free energies through conventional molecular dynamics, due to long biological timescales and extremely high flexibility of the peptides. Based on the Gaussian accelerated molecular dynamics (GaMD) enhanced sampling technique, we have developed a new computational method “Pep-GaMD,” which selectively boosts essential potential energy of the peptide in order to effectively model its high flexibility. In addition, another boost potential is applied to the remaining potential energy of the entire system in a dual-boost algorithm. Pep-GaMD has been demonstrated on binding of three model peptides to the SH3 domains. Independent 1 µs dual-boost Pep-GaMD simulations have captured repetitive peptide dissociation and binding events, which enable us to calculate peptide binding thermodynamics and kinetics. The calculated binding free energies and kinetic rate constants agreed very well with available experimental data. Furthermore, the all-atom Pep-GaMD simulations have provided important insights into the mechanism of peptide binding to proteins that involves long-range electrostatic interactions and mainly conformational selection. In summary, Pep-GaMD provides a highly efficient, easy-to-use approach for unconstrained enhanced sampling and calculations of peptide binding free energies and kinetics.
Stochastic nonlinear Schrödinger equation on an upper-right quarter plane with Dirichlet random boundary
Authors: Kaikina Elena I. , Sotelo-Garcia Norma
Published: October 2020

In this paper, we study the nonhomogeneous stochastic initial-boundary value problem for the nonlinear Schrödinger equation on an upper-right quarter plane with random Dirichlet boundary conditions. The main novelty of this work is a convenient framework for the analysis of such equations excited by the Wiener additive noise on the boundary. Our approach allows us to show the local existence and uniqueness of solutions in the space H2. The basic properties of the solutions such as the continuity and the boundary-layer behavior are also studied using the Itô calculus. Despite several technical difficulties, we believe that the approach developed in this paper can be applied to the case of a large class of noise including fractional Wiener space time white noise, homogeneous noise, and Levy noise.
Thin-film thermoelectric generator based on polycrystalline SiGe formed by Ag-induced layer exchange
Authors: Tsuji M. , Murata M. , Yamamoto A. , Suemasu T. , Toko K.
Published: October 2020

SiGe alloys are a promising material for highly reliable, human-friendly thin-film thermoelectric generators for micro-energy harvesting. However, it is difficult to obtain high performances at low thermal budgets in SiGe layers, especially in n-type materials. Ag-induced layer exchange enables the synthesis of Si1−xGex (x: 0–0.3) layers at 500 °C and dynamically controls the Fermi level owing to the self-organizing manner of impurity doping during the layer exchange. Intrinsic, p-type (hole concentration >1019 cm−3), and highly n-type (electron concentration >1020 cm−3) SiGe layers are obtained using pure Ag, B-doped Ag, and As-doped Ag, respectively. Owing to the high carrier concentrations, the thermoelectric power factor at room temperature exhibits high values: 230 μW m−1 K−2 for the p-type and 1000 μW m−1 K−2 for the n-type. The latter value is the highest reported power factor at room temperature for SiGe formed below 1000 °C. The dimensionless figure of merit is determined to be 0.19 from the power factor and the thermal conductivity of 1.6 W m−1 K−1. A thermoelectric generator fabricated with the low-temperature SiGe layers demonstrates a relatively large output for thin films (50 nm): 1.4 nW at room temperature with a temperature difference of 15 °C.
Expectation maximized molecular dynamics: Toward efficient learning of rarely sampled features in free energy surfaces from unbiased simulations
Authors: Dutta Pallab , Sengupta Neelanjana
Published: October 2020

Biophysical processes often encounter high energy transition states that lie in regions of the free energy landscape (FEL) inaccesible to conventional molecular dynamics simulations. Various enhanced sampling methods have been developed to handle the inherent quasi-nonergodicity, either by adding a biasing potential to the underlying Hamiltonian or by forcing the transitions with parallel tempering. However, when attempting to probe systems of increasing complexity with limited computational resources, there arises an imminent need for fast and efficient FEL exploration with sufficient accuracy. Herein, we present a computationally efficient algorithm based on statistical inference for fast estimation of key features in the two-dimensional FEL. Unlike conventional enhanced sampling methods, this newly developed method avoids direct sampling of high free energy states. Rather, the transition states connecting metastable regions of comparable free energies are estimated using Bayesian likelihood maximization. Furthermore, the method incorporates a tunable self-feedback mechanism with classical molecular dynamics for preventing unnecessary sampling that no more effectively contributes to the underlying distributions of metastable states. We have applied this novel protocol in three independent case studies and compared the results against a conventional method. We conclude with the scope of further developments for improved accuracy of the new method and its generalization toward estimation of features in more complex FELs.
A first-principles Quantum Monte Carlo study of two-dimensional (2D) GaSe
Authors: Wines Daniel , Saritas Kayahan , Ataca Can
Published: October 2020

Two-dimensional (2D) post-transition metal chalcogenides (PTMCs) have attracted attention due to their suitable bandgaps and lower exciton binding energies, making them more appropriate for electronic, optical, and water-splitting devices than graphene and monolayer transition metal dichalcogenides. Of the predicted 2D PTMCs, GaSe has been reliably synthesized and experimentally characterized. Despite this fact, quantities such as lattice parameters and band character vary significantly depending on which density functional theory (DFT) functional is used. Although many-body perturbation theory (GW approximation) has been used to correct the electronic structure and obtain the excited state properties of 2D GaSe, and solving the Bethe–Salpeter equation (BSE) has been used to find the optical gap, we find that the results depend strongly on the starting wavefunction. In an attempt to correct these discrepancies, we employed the many-body Diffusion Monte Carlo (DMC) method to calculate the ground and excited state properties of GaSe because DMC has a weaker dependence on the trial wavefunction. We benchmark these results with available experimental data, DFT [local-density approximation, Perdew-Burke-Ernzerhof (PBE), strongly constrained and appropriately normed (SCAN) meta-GGA, and hybrid (HSE06) functionals] and GW-BSE (using PBE and SCAN wavefunctions) results. Our findings confirm that monolayer GaSe is an indirect gap semiconductor (Γ-M) with a quasiparticle electronic gap in close agreement with experiment and low exciton binding energy. We also benchmark the optimal lattice parameter, cohesive energy, and ground state charge density with DMC and various DFT methods. We aim to present a terminal theoretical benchmark for pristine monolayer GaSe, which will aid in the further study of 2D PTMCs using DMC methods.
The effect of vacancy-impurity complexes in silicon on the current–voltage characteristics of p–n junctions
Authors: Bulyarskiy Sergey V. , Lakalin Alexander V. , Saurov Mikhail A. , Gusarov Georgy G.
Published: October 2020

The methods for analyzing the current–voltage characteristics of p–n junctions at forward and reverse bias with the calculation of the parameters of recombination centers before and after irradiation with gamma quanta were developed in this work. These methods are simple, convenient, and allow one to determine the parameters of deep levels at one temperature, which makes it possible to use them as express diagnostic techniques, taking measurements immediately on the semiconductor plates at the completion of the main technological processes. It was shown that after irradiation the composition of the centers in the depletion region of the p–n junction changes, the recombination processes and the lifetime begin to determine the divacancy complexes of silicon with oxygen (V2O). It was found that the generation of charge carriers in a strong field of the depletion region of the p–n junction occurs under the influence of the electron–phonon interaction, the parameters of this interaction are determined, and the configuration-coordinate diagrams of recombination centers are constructed.
Kinetic simulations of laser-induced plume expansion from a copper target into a vacuum or argon background gas based on ab initio calculation of Cu–Cu, Ar–Ar, and Ar–Cu interactions
Authors: Petrov Vitaly A. , Ranjbar Omid A. , Zhilyaev Petr A. , Volkov Alexey N.
Published: October 2020

The kinetic simulations of plume expansion induced by pulsed laser heating of a copper target in a vacuum or low-pressure argon background gas are performed based on the direct simulation Monte Carlo (DSMC) method and ab initio quantum mechanical calculation of interactions between copper and argon atoms. The potential energy curves (PECs) for Cu–Cu, Ar–Ar, and Ar–Cu interactions are obtained in density functional theory (DFT) calculations with the van der Waals (vdW) correction. The computed Cu–Cu PEC is strikingly different from the Lennard-Jones (LJ) potentials with semi-empirical parameters, which were previously suggested for kinetic simulations of the copper vapor flows. It is found that the Lorentz–Berthelot rule cannot reliably predict the parameters of the LJ potential for cross-species Ar–Cu interaction. The DFT-vdW PECs are fitted by the Morse long-range (MLR) potentials. The MLR potentials are used to compute the outcomes of binary collisions in the DSMC method based on the solution of the classical scattering problem and to parameterize the variable hard sphere (VHS) collision model. The results of the DSMC simulations based on DFT-vdW PECs are compared with the results obtained based on various parameterizations of the VHS model. It is shown that the previously developed parameterizations of the VHS model can either over- or underestimate the plume temperature and density compared to the results obtained based on the DFT-vdW PECs. The simulations also reveal the strong effect of the cross-species collision model parameters on the flow structure in the mixing layer, which is dominated by molecular diffusion.
Off-diagonal derivative discontinuities in the reduced density matrices of electronic systems
Authors: Cioslowski Jerzy
Published: October 2020

An explicit expression relating the magnitude of the fifth-order off-diagonal cusp in the real part of the one-electron reduced density matrix to the “on-top” two-electron density is derived in a rigorous manner from the behavior of the underlying electronic wavefunction at the electron–electron coalescence. The implications of the presence of this cusp upon electronic structure calculations of quantum chemistry and solid-state physics, including the limits imposed upon their accuracy, are elucidated. In particular, the power-law decay of the occupation numbers of the natural orbitals is demonstrated for 1S states of systems composed of arbitrary even numbers of electrons. The practical importance of analogous off-diagonal cusps in many-electron reduced density matrices is briefly discussed.
An entertaining physics: On the possibility of energy storage enhancement in electrostatic capacitors using the compensational inductive electric field
Authors: Khitun Alexander
Published: October 2020

In this work, we consider the possibility of energy storage enhancement in electrostatic capacitors using the compensational method. The essence of the proposed approach is the use of inductive voltage Vind to partially compensate the electrostatic voltage q/C produced by the electric charges on the capacitor plates. We hypothesize that it may be possible to increase the amount of charge stored on the plates before the breakdown and increase the energy stored in the capacitor using the compensational inductive voltage. There are several possible scenarios of manipulating the inductive voltage to increase the amount of energy released via the discharge. We also consider several electro-magnetic capacitors for practical utilization. Potentially, the energy per volume stored in a simple parallel plate capacitor may exceed that of gasoline. The physical limits and technological shortcomings of the proposed approach are also discussed.
Towards resilient health systems for increasing climate extremes: insights from the 2019–20 Australian bushfire season
Authors: Lal Aparna , Patel Mahomed , Hunter Arnagretta , Phillips Christine
Published: October 2020

The public health emergency associated with the 2019–20 bushfires in Australia was a wake-up call to increase the resilience of our health systems to respond to climate extremes. We must combine our understanding of predictions of extreme weather events with our knowledge on emergency preparedness and response to protect the health of citizens.
Forelimb force direction and magnitude independently controlled by spinal modules in the macaque
Authors: Yaron Amit , Kowalski David , Yaguchi Hiroaki , Takei Tomohiko , Seki Kazuhiko
Published: October 2020

Significance

Studies in frogs and rodents have shown that to deal with the complexity of controlling all the muscles in the body the brain can activate sets of neurons in the spinal cord with a single signal. Here, we provide confirmation of a similar system of “modular” output in nonhuman primates. Costimulation at two spinal sites resulted in force field directionality that was the linear sum of the fields from each site. However, unlike the frog and rodent, the magnitude of the force vectors was greater than the simple sum (supralinear). Thus, while force direction in primates is controlled by the linear sum of modular output, force amplitude might be adjusted by additional sources shared by those modules.