bluuebunny/crossref_metadata_2025 huggingface dataset:
Effectiveness of Video Assisted Teaching Program on Knowledge Regarding Prevention and Management of Laryngitis among Primary School Teachers of Selected Primary Schools at Hassan
Authors: B. Mamatha , S. Damayanthi
Published: April 2020

Background: Teaching is a profession where teachers are exposed to use their voice excessively in many situations which impose the risk for developing morbidity caused to larynx, among them the most common is laryngitis. However, I felt that there was great need for educating primary school teachers on Prevention and Management of Laryngitis.

Objectives: To find the effectiveness of Video Assisted Teaching Program (VATP) on Knowledge regarding Prevention and Management of Laryngitis among Primary School Teachers.

Materials and methods: Quasi-experimental research design was adopted for the study with purposive sampling technique to select the sample (N=60) with n=30 in experimental group and control group of primary school teachers respectively. A structured knowledge questionnaire was used to assess the Knowledge; VATP was administered only to experimental group to find its effectiveness in comparison with control group. The findings of the study revealed deficit in knowledge of primary school teachers before administration of VATP.

Results: The mean percentage knowledge score of post-test (79.80 %) was higher than the pretest (39.30%). The calculated paired 't' value is greater than the table value (0.05, 29df) = 2.045. It showed a significant difference between mean pre and post- test knowledge scores among experimental group. The mean percentage of knowledge scores in post-test (79.80%) among experimental group was higher than the post-test (39.80%) among control group. The 2 calculated unpaired 't' value is greater than the table value (0.05,58df) = 1.96. Calculated ÷ values showed significant association between post-test knowledge scores of respondents with their selected demographic variables.

Conclusion: VATP was effective in increasing the knowledge of primary school teachers on Prevention and Management of Laryngitis.
A Novel Antigonadotropic Role of Thyroid Stimulating Hormone on Leydig Cell-Derived Mouse Leydig Tumor Cells-1 Line
Authors: Dhole Bodhana , Gupta Surabhi , Shekhar Skand , Kumar Anand
Published: April 2020

Subclinical hypothyroid men characterized by a rise in only thyroid stimulating hormone (TSH) levels, and normal thyroid hormone levels showed a fall in their serum progesterone and testosterone levels. This suggested a role of TSH in regulating Leydig cell steroidogenesis. Therefore, we investigated the direct role of TSH on steroid production and secretion using a mouse Leydig tumor cell line-1 (MLTC-1). MLTC-1 cells were treated with different doses of TSH isolated from porcine pituitary as well as recombinant TSH. Steroid secretion was measured by radioimmunoassay (RIA). The mRNA levels of steroidogenic enzymes were quantitated by real-time polymerase chain reaction (RT-PCR), whereas the corresponding protein levels were determined by western blot. In MLTC-1 cells, pituitary TSH as well as recombinant TSH inhibited progesterone and testosterone secretion in a dose-dependent manner. The inhibitory action of TSH on steroid secretion was unique and not mimicked by other anterior pituitary hormones including follicle stimulating hormone and adrenocorticotropic hormone. Recombinant TSH showed no effect on steroidogenic acute regulatory protein and CYP11A1, the enzymes catalyzing the nonsteroidogenic and steroidogenic rate-limiting steps of steroid synthesis, respectively. Recombinant TSH was shown to inhibit steroidogenesis in MLTC-1 cells by inhibiting the 3-β hydroxy steroid dehydrogenase mRNA and protein levels, the enzyme that catalyzes the conversion of pregnenolone to progesterone. This inhibitory effect of TSH is probably direct as both mRNA and protein of the TSH receptor were shown to be present in the MLTC-1 cells.
Trapped in the prison of the mind: Notions of climate-induced (im)mobility decision-making and wellbeing from an urban informal settlement in Bangladesh
Authors: Ayeb-Karlsson Sonja , Kniveton Dominic , Cannon Terry
Published: April 2020

The concept of Trapped Populations has until date mainly referred to people ‘trapped’ in environmentally high-risk rural areas due to economic constraints. This article attempts to widen our understanding of the concept by investigating climate-induced socio-psychological immobility and its link to Internally Displaced People’s (IDPs) wellbeing in a slum of Dhaka. People migrated here due to environmental changes back on Bhola Island and named the settlement Bhola Slum after their home. In this way, many found themselves ‘immobile’ after having been mobile—unable to move back home, and unable to move to other parts of Dhaka, Bangladesh, or beyond. The analysis incorporates the emotional and psychosocial aspects of the diverse immobility states. Mind and emotion are vital to better understand people’s (im)mobility decision-making and wellbeing status. The study applies an innovative and interdisciplinary methodological approach combining Q-methodology and discourse analysis (DA). This mixed-method illustrates a replicable approach to capture the complex state of climate-induced (im)mobility and its interlinkages to people’s wellbeing. People reported facing non-economic losses due to the move, such as identity, honour, sense of belonging and mental health. These psychosocial processes helped explain why some people ended up ‘trapped’ or immobile. The psychosocial constraints paralysed them mentally, as well as geographically. More empirical evidence on how climate change influences people’s wellbeing and mental health will be important to provide us with insights in how to best support vulnerable people having faced climatic impacts, and build more sustainable climate policy frameworks.
Response to “Comment on ‘Classification of Lie point symmetries for quadratic Liénard type equation
ẍ + f(x)ẋ2 + g(x) = 0’” [J. Math. Phys. 61, 044101 (2020)]
Authors: Chandrasekar V. K. , Tiwari A. K. , Pandey S. N. , Senthilvelan M. , Lakshmanan M.
Published: April 2020

We respond to the comment on ‘Classification of Lie point symmetries for quadratic Liénard type equation ẍ + f(x)ẋ2 + g(x) = 0’ [J. Math. Phys. 61, 044101 (2013)] by Iacono regarding linearizability and isochronicity. We assert here that the condition for linearization of the equation ẍ + f(x)ẋ2 + g(x) = 0 given by us in our paper is correct with the condition g1=ω02>0. We present the explicit form of local and nonlocal transformations that transform the quadratic Liénard equation ẍ+F+11−xẋ2+x(1−x)(1+Dx)=0 into the harmonic oscillator equation for the four cases mentioned in the comment and confirm the statements given in our paper are all valid.
Complex bursting dynamics in an embryonic respiratory neuron model
Authors: Wang Yangyang , Rubin Jonathan E.
Published: April 2020

Pre-Bötzinger complex (pre-BötC) network activity within the mammalian brainstem controls the inspiratory phase of the respiratory rhythm. While bursting in pre-BötC neurons during the postnatal period has been extensively studied, less is known regarding inspiratory pacemaker neuron behavior at embryonic stages. Recent data in mouse embryo brainstem slices have revealed the existence of a variety of bursting activity patterns depending on distinct combinations of burst-generating INaP and ICAN conductances. In this work, we consider a model of an isolated embryonic pre-BötC neuron featuring two distinct bursting mechanisms. We use methods of dynamical systems theory, such as phase plane analysis, fast–slow decomposition, and bifurcation analysis, to uncover mechanisms underlying several different types of intrinsic bursting dynamics observed experimentally including several forms of plateau bursts, bursts involving depolarization block, and various combinations of these patterns. Our analysis also yields predictions about how changes in the balance of the two bursting mechanisms contribute to alterations in an inspiratory pacemaker neuron activity during prenatal development.
A compact high-resolution spectrometer based on a segmented conical crystal analyzer
Authors: Robledo José I. , Pérez Carlos A. , Sánchez Héctor J.
Published: April 2020

In this work, the design, fabrication, and evaluation of a compact, one-shot spectrometer based on a segmented conically bent crystal analyzer are described. The system is a “one-shot” wavelength dispersive spectrometer, which has a crystal analyzer with an innovative geometry. It reaches an energy resolution of around 8 eV for Mn Kα1 line, which is at least an order of magnitude better than the commonly used energy dispersive spectrometers for fluorescence, and is comparable to current wavelength dispersive spectrometers. The prototype spectrometer fabricated in this work avoids angle scans that most wavelength dispersive spectrometers require, has the advantage of a sample–detector distance of only 146 mm, and allows for the simultaneous measurement of approximately a 2 keV window. This system is suitable to be used at synchrotron radiation facilities and free electron lasers, and it can even be adapted to an x-ray tube in any conventional x-ray laboratory.
Direct observation of charge accumulation in quantum well solar cells by cross-sectional Kelvin probe force microscopy
Authors: Noda Takeshi , Ishida Nobuyuki , Mano Takaaki , Fujita Daisuke
Published: April 2020

We report here the direct observation of charge accumulation in GaAs/AlGaAs multiple quantum well (MQW) solar cells by employing cross-sectional Kelvin probe force microscopy (KPFM). This sample is characterized by thin barrier layers that enable miniband formation. The contact potential difference, or potential between the tip and the semiconductor sample, was measured along the p–i–n junction. We observed, under illuminated conditions, a change in the potential gradient, or bending, at a position of the MQW layer, but not in the reference sample without quantum well. This clearly shows that charge is accumulated in the MQW region. We also found that electron accumulation in the MQW layer and the density measured on the surface is about 1 × 1011 cm−2. Our experimental results show that KPFM is a powerful way of understanding the device physics of nanostructure-based solar cells.
Numerical analysis of the interaction of two underwater explosion bubbles using the compressible Eulerian finite-element method
Authors: Liu Nian-Nian , Zhang A-Man , Liu Yun-Long , Li Tong
Published: April 2020

This paper presents numerical investigations of the nonlinear interactions between two underwater explosion (UNDEX) bubbles using the compressible Eulerian finite-element method (EFEM). The volume of fluid method is applied to capture the multi-fluid interface. In this model, the high-temperature and high-pressure gaseous products inside the UNDEX bubble are described by the equation of state for Jones–Wilkins–Lee, which allows us to consecutively simulate the propagation of the primary explosion shock wave and multi-period bubble pulsations. To verify the efficiency and accuracy of the present model, comparisons with experimental data are performed, showing that both the dynamic behaviors of oscillating bubbles and the pressure profiles of primary shock waves, bubble pulsations, and jetting loads are highly consistent. In addition, it is found that the EFEM model can satisfactorily reproduce the complex characteristics of interacting bubbles, such as the coalescence and splitting that occur during later pulsating cycles in bubbles. On this basis, the effects of the initial bubble–bubble distance γbb and buoyancy parameter δ on the features of bubble interactions and the corresponding pressure loads in the flow field are analyzed and discussed. In particular, the pressure induced by two identical UNDEX bubbles (each generated by detonation of an explosive with weight W) is compared to that induced by a single bubble generated by an explosive with weight W or 2W to provide the basic technical support and reference for the design of multiple-weapon attacks in military engineering applications.
Ionic diffusioosmotic transport in nanochannels grafted with pH-responsive polyelectrolyte brushes modeled using augmented strong stretching theory
Authors: Sivasankar Vishal Sankar , Etha Sai Ankit , Sachar Harnoor Singh , Das Siddhartha
Published: April 2020

In this paper, we study the diffusioosmotic (DOS) transport in a nanochannel grafted with pH-responsive polyelectrolyte (PE) brushes and establish brush-functionalization-driven enhancement in induced nanofluidic electric field and electrokinetic transport. The PE brushes are modeled using our recently developed augmented strong stretching theory. We consider the generation of the DOS transport due to the imposition of a salt concentration gradient along the length of the nanochannel. The presence of the salt concentration gradient induces an electric field that has an osmotic (associated with the flow-driven migration of the ions in the induced electric double layer) and an ionic (associated with the conduction current) component. These two components evolve in a manner such that the electric field in the brush-grafted nanochannel is larger (smaller) in magnitude than that in the brush-less nanochannels for the case where the electric field is positive (negative). Furthermore, we quantify the DOS flow velocity and establish that for most of the parameter choices, the DOS velocity, which is a combination of the induced pressure-gradient-driven chemiosmotic component and the induced electric field driven electroosmotic transport, is significantly larger for the nanochannels grafted with backbone-charged PE brushes (i.e., brushes where the charge is distributed along the entire length of the brushes) as compared to brush-free nanochannels or nanochannels grafted with PE brushes containing charges on their non-grafted ends.
Electron transport analysis of 4H-SiC with full-band Monte Carlo simulation including real-space Coulomb interactions
Authors: Cheng Chi-Yin , Vasileska Dragica
Published: April 2020

4H-SiC has been widely used in many applications. All of these benefit from its extremely high critical electric field with good electron mobility. 4H-SiC possesses a critical field ten times higher than that of Si, which allows high-voltage blocking layers composed of 4H-SiC to be approximately a tenth the thickness of a comparable Si device, thus reducing the device on-resistance and power losses, while maintaining the same high blocking capability. Unfortunately, commercial Technology for Computer-Aided Design tools like Sentaurus and Silvaco Atlas are based on effective mass approximation, while most 4H-SiC devices are not operated under a low electric field so the parabolic-like band approximation does not hold anymore. Hence, to get more accurate and reliable simulation results, full-band analysis is needed. The first step in the development of a full-band device simulator is the calculation of the band structure. In this work, the empirical pseudopotential method is adopted. The next task in the sequence is the calculation of the scattering rates. Acoustic, non-polar optical phonon, polar optical phonon, and Coulomb scattering are considered. Coulomb scattering is treated in real space using the particle–particle–particle–mesh approach. The third task is coupling the bulk full-band solver with a 3D Poisson equation solver to generate a full-band device simulator. For proof-of-concept of the methodology adopted here and for simplicity, a 3D resistor is simulated. From the resistor simulations, the low-field electron mobility dependence upon Coulomb scattering in 4H-SiC devices is extracted. The simulated low-field mobility results are in excellent agreement with available experimental data.
Variational and diffusion quantum Monte Carlo calculations with the CASINO code
Authors: Needs R. J. , Towler M. D. , Drummond N. D. , López Ríos P. , Trail J. R.
Published: April 2020

We present an overview of the variational and diffusion quantum Monte Carlo methods as implemented in the casino program. We particularly focus on developments made in the last decade, describing state-of-the-art quantum Monte Carlo algorithms and software and discussing their strengths and weaknesses. We review a range of recent applications of casino.
General limiting behavior of Riemann solutions to the non-isentropic Euler equations for modified Chaplygin gas
Authors: Song Yating , Guo Lihui
Published: April 2020

In this paper, the authors investigate the Riemann solutions of the non-isentropic Euler equations for the modified Chaplygin gas, which are the set of all rarefaction waves, shock waves, and contact discontinuity. For these Riemann solutions, the authors further consider their limiting behavior. In the process of analyzing the limiting behavior, the authors found that the delta shock wave is contained in the Riemann solutions of the non-isentropic Euler equations for the modified Chaplygin gas. Consequently, up to some appropriate conditions, there is unidirectional transformation from non-isentropic Euler equations for the modified Chaplygin gas to Chaplygin gas. On the basis of numerical simulations, the authors verified the reasonability of the theoretical analysis.
First-principles study of mechanical and electronic properties of Lu2SnC under pressure
Authors: Shao YaPing , Duan Wenshan
Published: April 2020

In this work, the structure, elastic, and electronic properties of the recently synthesized MAX phase Lu2SnC under pressure were studied by the first-principle calculation. The effect of high pressures, up to 20 GPa, on the structure shows that the compressibility along the a-axis was higher than that along the c-axis, which indicates that the Lu–C bonds are more resistant than Lu–Sn bonds. Meanwhile, we derived the elastic modulus (B, G, Y), Pugh’s ratio (G/B), Poisson’s ratio (ν), and averaged compressibility (β). The value of bulk moduli, Young’s moduli, and shear moduli increases under pressure, which means that the pressure can enhance the ability of resisting to shape change and improve the stiffness and hardness of Lu2SnC. Poisson’s ratio change from 0.184 to 0.246 in the 0–20 Gpa pressure range, which means that Lu2SnC is brittle in nature, this result is consistent with that obtained from the Cauchy pressure and Pugh’s ratio. In addition, we calculated the shear anisotropy factor (A), Ai (i = 1,2,3), AB, and AG. We found that the elastic anisotropy increases with increasing pressure. Finally, the electronic properties of Lu2SnC were calculated. As the pressure increases, a pseudo-gap appears in the energy range of −2eV to −3eV. The total density of state at the Fermi level remains virtually unchanged with the increasing pressure. We hope that our study can complement the future experimental and theoretical work, which can lead to further insights.
Harmonic magneto-dielectric study in doped-, double-, and layered-perovskites
Authors: Sahlot Pooja , Pandey Suchita , Pandey Adityanarayan , Awasthi A. M.
Published: April 2020

Harmonic magneto-dielectricity studied for the perovskite systems—Pb0.98Gd0.02(Mg1/3Nb2/3)0.995O3 (PGMN), La0.95Ca0.05CoO3 (LCCO), La2NiMnO6 (LNMO), and Ca3Mn2O7 (CMO), precisely characterizes intricately polarized phases. In magnetically co-doped PGMN, the first-harmonic signal (χ2′) manifests finite polarization P(H) below 270 K, corroborated by the measured remnant P–E traces. The second harmonic (χ3′) reveals the effect of random E-fields, causing electrical vitreousity. In spin-state LCCO, across the 65K-start of intermediate- (IS) to low-spin (LS) transition, harmonic susceptibilities evidence IS/LS-interfacial hyper-polarizations, and ac-/dc- conductivities exhibit mechanism-changeovers. In charge-transfer LNMO, dual magneto-electricity due to Ni2+ ↔ Mn4+ charge-hopping (intrinsic) and Maxwell–Wagner (fictitious) polarizations gets distinguished via χ2′. In hybrid improper ferroelectric (HIF) CMO, while the χ2,3′-signals clearly evidence stabilization of the ferroelectric state below 50 K, χ3′ and ɛ* discern the super-paraelectric, coupled-relaxor, and glassy phases, magneto-electrically coexistent with short-range spin-correlations, antiferromagnetic, and weak-ferromagnetic states, respectively. Our results on a variety of perovskites establish harmonics' exclusivity in revealing novel phases and superiority in divulging subtly variant states, either escaping detection or rendered indescript by usual electrical characterizations.
A more stable design for a pulsed optically pumped atomic clock
Authors: Mandel Savannah
Published: April 2020

A pulsed optically pumped atomic clock is presented with a frequency stability of 4.7×10−15 at 104 seconds.
Kinetics of the simplest criegee intermediate CH2OO reacting with CF3CF=CF2
Authors: Chen Yang , Zhou Xiao-hu , Liu Yi-qiang , Jin Yu-qi , Dong Wen-rui , Yang Xue-ming
Published: April 2020

CF3CF=CF2 is a potential source of atmospheric trifluoroacetic acid (CF3C(O)OH). The kinetics of the reaction of the simplest Criegee intermediate (CH2OO) with CF3CF=CF2 was studied by using the OH laser-induced fluorescence method. At 10 torr, the rate co-efficients were measured to be (1.45±0.14)×10−13, (1.18±0.11)×10−13, (1.11±0.08)×10−13, and (1.04±0.08)×10−13 cm3·molecule−1·s−1 at 283, 298, 308 and 318 K, respectively. The activation energy of (−1.66±0.21) kcal/mol was derived from the Arrhenius equation. No obvious pressure dependence was observed.
All-electrical manipulation of magnetization in magnetic tunnel junction via spin–orbit torque
Authors: Kong W. J. , Wan C. H. , Guo C. Y. , Fang C. , Tao B. S. , Wang X. , Han X. F.
Published: April 2020

Besides spin-transfer torque, spin–orbit torque (SOT) provides us with another electrical way for developing magnetic random access memory (MRAM) based on magnetic tunnel junctions (MTJs). By using a CoFeB/Ta/CoFeB T-type magnetic structure as a synthetic free layer, we have realized a magnetic-field-free MTJ switchable by SOT. In the T-type structure, an in-plane CoFeB layer is coupled to a perpendicular CoFeB layer via a Ta spacer. The spacer layer not only mediates exchange coupling but also generates strong SOT, which drives sharp switching between the low and high resistance states of the MTJ without any applied magnetic fields. This work could provide an efficient way toward realization of field-free SOT-MRAM or logic devices.
A new diabatization scheme for direct quantum dynamics: Procrustes diabatization
Authors: Richings Gareth W. , Habershon Scott
Published: April 2020

We present a new scheme for diabatizing electronic potential energy surfaces for use within the recently implemented direct-dynamics grid-based class of computational nuclear quantum dynamics methods, called Procrustes diabatization. Calculations on the well-studied molecular systems LiF and the butatriene cation, using both Procrustes diabatization and the previously implemented propagation and projection diabatization schemes, have allowed detailed comparisons to be made, which indicate that the new method combines the best features of the older approaches; it generates smooth surfaces, which cross at the correct molecular geometries, reproduces interstate couplings accurately, and hence allows the correct modeling of non-adiabatic dynamics.
Uniform multilevel switching of graphene oxide-based RRAM achieved by embedding with gold nanoparticles for image pattern recognition
Authors: Qi Meng , Cao Shuo , Yang Liu , You Qi , Shi Libin , Wu Zhiying
Published: April 2020

Traditional metal-oxide semiconductor devices are inadequate for use in artificial neural networks (ANNs) owing to their high power consumption, complex structures, and difficult fabrication techniques. Resistive random access memory (RRAM) is a promising candidate for ANNs owing to its simple structure, low power consumption, and excellent compatibility with CMOS. Moreover, it can mimic synaptic functions because of its multilevel resistive switching (RS) behavior. Herein, we demonstrate highly uniform RS and a high on/off ratio of RRAM based on graphene oxide by embedding gold nanoparticles into the device. This allowed reliable multilevel storage. Further, multilevel RRAM based on spike-timing-dependent-plasticity learning rules was used for image pattern recognition. These findings may offer a route to develop reliable digital memristors for ANNs.
Gas-loading furnace for deuterium-charged alloy-casting
Authors: Werner T. , Lehmann P. , Baumann J. , Kargl F. , Tyburska-Püschel B.
Published: April 2020

A furnace was developed and characterized to allow for safe and controlled gas-loading or degassing of alloys. This oven is able to process samples under varying atmospheres, such as high vacuum or nitrogen containing 10 vol. % deuterium, as well as for pressures up to 800 hPa. Thermal desorption spectroscopy and scanning electron microscopy demonstrate the enhancing effects of high loading-gas concentration, high pressures, high temperatures above liquidus (50–150 K above the liquidus temperature of the cast hypoeutectic aluminum–copper model-alloy), and long holding times (up to 60 min) on the amount of retained gas in the solidified sample. Lack of copper segregation in the casting is confirmed by energy dispersive x-ray diffraction and Rutherford backscattering spectroscopy. It is shown that the facility allows for the controlled generation of distinct amounts of gas pores, down to a nil amount (only shrinkage porosity appearing in the sample).
Scaling magnetic tunnel junction down to single-digit nanometers—Challenges and prospects
Authors: Jinnai Butsurin , Watanabe Kyota , Fukami Shunsuke , Ohno Hideo
Published: April 2020

Magnetic tunnel junction (MTJ), a spintronics device, has been intensively developed in the past couple of decades because of its high potential in terms of non-volatility, fast operation, virtually infinite endurance, scalability, and compatibility with complementary metal-oxide-semiconductor (CMOS) integrated circuits as well as their process and circuits. Today, high-volume manufacturing of spin-transfer torque magnetoresistive random access memory based on MTJ has been initiated for embedded memory applications in CMOS logic. Whether MTJ is scalable along with the advancement of CMOS technology is critical for the technology's future. Here, we review the scaling of MTJ technology, from in-plane anisotropy MTJs to perpendicular interfacial- or shape-anisotropy MTJs. We also discuss challenges and prospects in the future 1X- and X-nm era.
Heat transfer in magnetohydrodynamic nanofluid flow past a circular cylinder
Authors: K. S. Arjun , K. Rakesh
Published: April 2020

Multi-phase modeling considering the nanofluid heterogeneity and slip velocity is not explored in simulating nanofluid flow and heat transfer at higher Reynolds numbers (Re). A comprehensive study of turbulent flow around hot circular cylinders is lacking. The flow patterns are not tackled, and the relationship between flow behaviors and force variations due to the influencing parameters is not established. The heat transfer enhancement and hydrodynamics with forced convection in a rectangular duct are investigated using Ansys FLUENT 15.0, applying a nodal spectral-element method based on the Eulerian-mixture model. The current investigation focuses on demonstrating the correlation between high Re values, size of the bluff body in relation to duct height, nanoparticle volume fraction, magnetic field strength, and heat transfer for magnetohydrodynamic flow. In general, the Nusselt number (Nu) increases with Re, cylinder diameter in relation to duct height, and nanoparticle volume fraction (ϕ) and decreases with the Hartmann number (Ha), except at Ha 0 ≤ 20. Nu increases with Ha from 0 to 20 with a drastic increase up to Ha = 10 and moderate from 10 to 20 with augment of Ha. The best heat transfer enhancement case is reported with the identification of ideal influencing parameters. The significant finding is that the control of flow over a circular cylinder for heat transfer enhancement using different parameters significantly changes vortical structures in the wake and reduces mean drag and lift fluctuations, destabilizes the shear layer and reattaches the flow on the surface before main separation, which delays main separation and decreases drag, and finally reduces the lift fluctuations.
High performance CsPbBr3 quantum dots photodetectors by using zinc oxide nanorods arrays as an electron-transport layer
Authors: Wang Huaxin , Zhang Pengfei , Zang Zhigang
Published: April 2020

The electron transport layer (ETL) in perovskite photodetectors is playing a vital role in highly efficient electron extraction. Herein, this work reports a perovskite photodetector based on hydrothermal-fabricated ZnO nanorods (NRs) as the ETL and hot-injection-fabricated CsPbBr3 quantum dot (QD) as the photoabsorber. The crystalline structure, morphologies, and photoluminescence (PL) of the materials and the physics mechanism of highly efficient electron extraction in the devices are characterized and analyzed. The PL and time-resolved PL confirm the reduced recombination and enhanced electron transport to the indium tin oxide anode. The photodetectors based on ZnO NRs/CsPbBr3 QDs exhibit enormous enhancement in the response parameters such as a rise time of 12 ms, a decay time of 38 ms, and an on/off ratio of 3000, compared with the photodetectors based on ZnO films/CsPbBr3 QDs. These results indicate that the fabricated ZnO NRs/CsPbBr3 QDs heterojunction has a wide prospect of future applications in photodetectors.
Strain-tunable III-nitride/ZnO heterostructures for photocatalytic water-splitting: A hybrid functional calculation
Authors: Zhang Zhaofu , Huang Bingquan , Qian Qingkai , Gao Zhibin , Tang Xi , Li Baikui
Published: April 2020

Solar to fuel energy conversion is one of the momentous topics nowadays considering the urgent demand for clean energy supplies. In this work, the tunable electronic and optical properties of III-nitride/ZnO 2D/2D heterostructures (including GaN/ZnO, AlN/ZnO, and GaN/AlN) by strain engineering were investigated by first-principles calculations. The studied heterostructures feature a small interlayer distance, with the cation of one layer directly above the anion of the other layer, and vice versa. This leads to a strong binding energy and interlayer coupling across the heterostructure. The built-in field induced by the charge redistribution facilitates the photoexcited carrier migration, which is beneficial to the photocatalytic water splitting application. The stable III-nitride/ZnO heterostructures exhibit decent band edge positions with biaxial strain engineering and feature an enhancement of optical absorption under tensile strain. Our results indicate that the III-nitride/ZnO 2D/2D heterostructures are promising photocatalysts for solar to hydrogen generation by water splitting.
An improved differential-grating plane-mirror heterodyne interferometer for small roll angle measurement of a linear motion
Authors: Tang Shanzhi , Ren Zhongrui , Han Qingfu , Sheng Weifan , Li Ming
Published: April 2020

In the previous studies on roll angle (ROLL) measurements which are based on the concept of the combination of a diffraction grating displacement technique and a laser heterodyne interferometry, there is always a lack of ideally functional retro-reflectors and corresponding optical configurations resulting in misalignment and unconfident monitoring. To overcome this problem, a differential-grating plane-mirror heterodyne interferometer is proposed in this paper, in which the grating displacement sensing method is utilized to promote angular interferometry as a reliable ROLL measurement. The working mechanism is thoroughly demonstrated through the theoretical derivation and performance analysis. In particular, the exploited configuration here including a differential grating with excellent robustness and a plane mirror with doubled resolution enables improved performance compared with the existing methods. Furthermore, a corresponding prototype is also developed to validate the proposed method successfully. So, it features merits such as an ultra-high resolution up to 1 nrad, a high sampling rate of kHz and easy practicability, which is significant for high-accuracy and real-time ROLL monitoring and compensation for advanced manufacturing and scientific instruments.
High-frequency current oscillations in charge-density-wave 1T-TaS2 devices: Revisiting the “narrow band noise” concept
Authors: Geremew Adane K. , Rumyantsev Sergey , Debnath Bishwajit , Lake Roger K. , Balandin Alexander A.
Published: April 2020

We report on the current oscillations in quasi-2D 1T-TaS2 charge-density-wave two-dimensional devices. The MHz-frequency range of the oscillations and the linear dependence of the frequency of the oscillations on the current closely resemble the narrow band noise, which was often observed in the classical bulk quasi-1D trichalcogenide charge-density-wave materials. In bulk quasi-1D materials, the narrow band noise was interpreted as direct evidence of charge-density-wave sliding. Despite the similarities, we argue that the nature of the MHz oscillations in 1T-TaS2 is different from the narrow band noise. Analysis of the biasing conditions and current indicates that the observed oscillations are related to the current instabilities due to the voltage-induced transition from the nearly commensurate to incommensurate charge-density-wave phase.
Deer antlers: traditional Chinese medicine use and recent pharmaceuticals
Authors: Li Chunyi
Published: April 2020

Deer velvet antlers (VA) have been used as a type of traditional Chinese medicine for over 2000 years, mainly for treating yang-deficiency syndromes. However, VA still largely remain a traditional remedy with scant science, although getting more attention as time goes. In recent years, our group has been trying to develop some efficacious drugs/functional food based on unique biological phenomena of VA, such as, for example, dead tissue (hard antler base) being attached to living tissue (pedicle) for over half a year without causing inflammation, a large-size wound (up to 10 cm in diameter) being left on top of a pedicle stump after previous antler casting healing within a week only with a negligible scar, and severely osteoporotic skeleton caused by intensive antler calcification fully reversing after the completion of antler calcification. Successful translation of these unique phenomena to clinical use would greatly benefit human health.
Theoretical Investigation of Main-Group Element Hydride Insertion into Phosphorus-Heterocyclic Carbenes (PHCs)
Authors: Al Furaiji Khalidah H. M. , Molino Andrew , Dutton Jason L. , Wilson David J. D.
Published: April 2020

Initial reports of ring expansion reactions (RER) of N-heterocyclic carbenes (NHCs) with main-group element hydrides have led to several synthetic and theoretical investigations, which include reports of insertion by Be, B, Al, Si, and Zn hydrides. The RERs generally lead to insertion of the heteroatom into the endocyclic C–N bond with formation of an expanded heterocyclic ring. Following the recent isolation of a P-heterocyclic carbene (PHC), here we report results from a computational study (RI-SCS-MP2/def2-TZVP//M06–2X/def2-TZVP) of RERs with a series of PHCs for the ring-insertion of silicon (SiH4, SiH2Ph2) and boron (BH3, BH2NMe2) hydrides. In order to explore the roles of both electronic and steric effects on PHCs and their reactivity, a series of P-substituent PHCR (R=H, Me, Ph, and bulky Ar groups) were investigated. Bulky R groups serve to maximise ring planarity and the σ-donating capability of the PHC. For RER, the PHC analogues exhibit facile initial hydride transfer from the main-group hydrides to the carbene carbon, with barriers that are substantially lower than with NHCs. However, the full ring insertion mechanisms for PHCs are, in general, kinetically unfavourable due to a large barrier associated with the ring-expansion step. While bulky P-substituents maximise heterocycle planarity towards that of NHCs, the RER reactivity with bulky PHCs does not reflect that of an NHC.
Foxp3 heterozygosity does not overtly affect mammary gland development during puberty or the oestrous cycle in mice
Authors: Atashgaran Vahid , Dasari Pallave , Hodson Leigh J. , Evdokiou Andreas , Barry Simon C. , Ingman Wendy V.
Published: April 2020

Female mice heterozygous for a genetic mutation in transcription factor forkhead box p3 (Foxp3) spontaneously develop mammary cancers; however, the underlying mechanism is not well understood. We hypothesised that increased cancer susceptibility is associated with an underlying perturbation in mammary gland development. The role of Foxp3 in mammary ductal morphogenesis was investigated in heterozygous Foxp3Sf/+ and wildtype Foxp3+/+ mice during puberty and at specific stages of the oestrous cycle. No differences in mammary ductal branching morphogenesis, terminal end bud formation or ductal elongation were observed in pubertal Foxp3Sf/+ mice compared with Foxp3+/+ mice. During adulthood, all mice underwent normal regular oestrous cycles. No differences in epithelial branching morphology were detected in mammary glands from mice at the oestrus, metoestrus, dioestrus and pro-oestrus stages of the cycle. Furthermore, abundance of Foxp3 mRNA and protein in the mammary gland and lymph nodes was not altered in Foxp3Sf/+ mice compared with Foxp3+/+ mice. These studies suggest that Foxp3 heterozygosity does not overtly affect mammary gland development during puberty or the oestrous cycle. Further studies are required to dissect the underlying mechanisms of increased mammary cancer susceptibility in Foxp3Sf/+ heterozygous mice and the function of this transcription factor in normal mammary gland development.
Production of styrene oxide from styrene by a recombinant Escherichia coli with enhanced AcrAB-TolC efflux pump level in an aqueous-organic solvent two-phase system
Authors: Doukyu Noriyuki , Iida Shinichiro
Published: April 2020

The AcrAB-TolC efflux pump is involved in the organic solvent tolerance of Escherichia coli. Most E. coli strains are highly sensitive to organic solvents such as n-hexane and cyclohexane. Here, a recombinant E. coli transformed with an expression plasmid containing acrAB and tolC became tolerant to n-hexane and cyclohexane. The levels of AcrA, AcrB, and TolC in the recombinant increased by 3- to 5-fold compared to those in the control strain without the plasmid for acrAB or tolC. To investigate the usability of the recombinant as a biocatalyst in an aqueous-organic solvent two-phase system, we further introduced xylMA xylene monooxygenase genes from Pseudomonas putida mt-2 into the recombinant and examined the production of styrene oxide from styrene. The resulting recombinant produced 1.8 mg and 1.0 mg styrene oxide mL−1 of medium in a medium overlaid with a 25% volume of n-hexane and cyclohexane containing 10% (wt vol−1) styrene, respectively.
Slc7a5 alters Kvβ-mediated regulation of Kv1.2
Authors: Lamothe Shawn M. , Kurata Harley T.
Published: April 2020

The voltage-gated potassium channel Kv1.2 plays a pivotal role in neuronal excitability and is regulated by a variety of known and unknown extrinsic factors. The canonical accessory subunit of Kv1.2, Kvβ, promotes N-type inactivation and cell surface expression of the channel. We recently reported that a neutral amino acid transporter, Slc7a5, alters the function and expression of Kv1.2. In the current study, we investigated the effects of Slc7a5 on Kv1.2 in the presence of Kvβ1.2 subunits. We observed that Slc7a5-induced suppression of Kv1.2 current and protein expression was attenuated with cotransfection of Kvβ1.2. However, gating effects mediated by Slc7a5, including disinhibition and a hyperpolarizing shift in channel activation, were observed together with Kvβ-mediated inactivation, indicating convergent regulation of Kv1.2 by both regulatory proteins. Slc7a5 influenced several properties of Kvβ-induced inactivation of Kv1.2, including accelerated inactivation, a hyperpolarizing shift and greater extent of steady-state inactivation, and delayed recovery from inactivation. These modified inactivation properties were also apparent in altered deactivation of the Kv1.2/Kvβ/Slc7a5 channel complex. Taken together, these findings illustrate a functional interaction arising from simultaneous regulation of Kv1.2 by Kvβ and Slc7a5, leading to powerful effects on Kv1.2 expression, gating, and overall channel function.
Variation theory as a lens for interpreting and guiding physics students’ use of digital learning environments
Authors: Euler Elias , Gregorcic Bor , Linder Cedric
Published: April 2020

In this paper, we examine the implementation of a digital learning environment—namely, the physics software, Algodoo—which is less-constrained in its design than the digital learning environments typically used in physics education. Through an analysis of a case study, we explore a teaching arrangement wherein physics teachers responsively guide small groups of students as they use less-constrained DLEs in a mostly self-directed manner. Our analysis leads to practical recommendations for physics teachers in terms of (1) how to glean useful information about students’ existing physics knowledge through observation and (2) how to responsively intervene so as to productively guide students toward the learning of particular physics content. These recommendations stem from our use of the variation theory of learning as a lens for physics students’ use of digital learning environments.
Probing surface charge densities on optical fibers with a trapped ion
Authors: Ong Florian R , Schüppert Klemens , Jobez Pierre , Teller Markus , Ames Ben , Fioretto Dario A , Friebe Konstantin , Lee Moonjoo , Colombe Yves , Blatt Rainer , Northup Tracy E
Published: April 2020

We describe a novel method to measure the surface charge densities on optical fibers placed in the vicinity of a trapped ion, where the ion itself acts as the probe. Surface charges distort the trapping potential, and when the fibers are displaced, the ion’s equilibrium position and secular motional frequencies are altered. We measure the latter quantities for different positions of the fibers and compare these measurements to simulations in which unknown charge densities on the fibers are adjustable parameters. Values ranging from −10 to +50 e µm−2 were determined. Our results will benefit the design and simulation of miniaturized experimental systems combining ion traps and integrated optics, for example, in the fields of quantum computation, communication and metrology. Furthermore, our method can be applied to any setup in which a dielectric element can be displaced relative to a trapped charge-sensitive particle.
An improved cellular automata model for TiN inclusion precipitation
Authors: Gao Xiaohan , Meng Xiangning , Cui Lei , Zhang Kun , Meng Yunfei , Zhu Miaoyong
Published: April 2020

The mesoscopic dendrite growth model in the solidification process of molten steel is established, based on the cellular automata model. To accurately describe the TiN nucleation process, a heterogeneous nucleation model was used to describe the TiN nucleation process. The accuracy of the dendrite growth model is verified by comparing the CA model and Lipton–Glicksman–Kurz (LGK) analytical model. The growth process of TiN precipitates was simulated by dynamic mesh generation. Meanwhile, the influence of grid anisotropy on dendrite growth is greatly weakened by introducing the decentered square algorithm, and the growth of the equiaxed crystal in all directions is simulated. The results show that the calculated results of the model are in good agreement with the volume and morphology of TiN observed in the experiment. Meanwhile, it is found that the smaller TiN will dissolve at the end of solidification, and there will be a re-precipitation. The precipitation time of High-N and High-Ti alloy systems with the same concentration product is basically the same, but the final precipitation solid fraction of TiN inclusions in High-N (small Ti/N) alloy is larger. N element is the decisive factor of TiN precipitation.
The effect of SO2 on the Ni-YSZ electrode of a solid oxide electrolyzer cell operated in co-electrolysis
Authors: Jeanmonod G , Diethelm S , Van Herle J
Published: April 2020

In this work, the effect of sulphur poisoning of the Ni-YSZ electrode of an SOEC operated in co-electrolysis mode was investigated. Short-term tests with exposure up to 5 ppmv of SO2 were performed at OCV and under polarization (

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). The two-stages degradation pattern observed consisted of an initial fast voltage increase followed by a slower voltage increase similar to that of an SOFC exposed to H2S. Electrochemical impedance spectroscopy and the analysis of the distribution of relaxation times showed that both the catalytic and electrochemical reactions were affected by SO2. After extended periods in SO2-free reactant, only a partial recovery of the performances was observed even when exposure amounted to only 0.5 ppmv of SO2 independently on the current density. A durability test at a constant polarization of

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showed a voltage ‘runaway’ behavior during successive exposures to 1 ppmv and 2 ppmv of SO2. This behavior originated from a drastic increase of the serial resistance, which almost completely recovered when the SO2 supply was cut. This behavior was not observed during exposure to 0.5 ppmv of SO2, suggesting that, in these test conditions, the voltage ‘runaway’ behavior could be avoided at a sub-ppmv level. Successive exposure-recovery cycles were found to weaken the SOEC tolerance to SO2 and a low frequency pseudo-inductive arc was observed in the impedance response during and after the second exposure to SO2.
Associations of Maternal Early-Pregnancy Glucose Concentrations With Placental Hemodynamics, Blood Pressure, and Gestational Hypertensive Disorders
Authors: Erkamp Jan S , Geurtsen Madelon L , Duijts Liesbeth , Reiss Irwin K M , Mulders Annemarie G M G J , Steegers Eric A P , Gaillard Romy , Jaddoe Vincent W V
Published: April 2020

BACKGROUND

Gestational diabetes mellitus is associated with increased risks of gestational hypertension and preeclampsia. We hypothesized that high maternal glucose concentrations in early pregnancy are associated with adverse placental adaptations and subsequently altered uteroplacental hemodynamics during pregnancy, predisposing to an increased risk of gestational hypertensive disorders.

METHODS

In a population-based prospective cohort study from early pregnancy onwards, among 6,078 pregnant women, maternal early-pregnancy non-fasting glucose concentrations were measured. Mid and late pregnancy uterine and umbilical artery resistance indices were assessed by Doppler ultrasound. Maternal blood pressure was measured in early, mid, and late pregnancy and the occurrence of gestational hypertensive disorders was assessed using hospital registries.

RESULTS

Maternal early-pregnancy glucose concentrations were not associated with mid or late pregnancy placental hemodynamic markers. A 1 mmol/l increase in maternal early-pregnancy glucose concentrations was associated with 0.71 mm Hg (95% confidence interval 0.22–1.22) and 0.48 mm Hg (95% confidence interval 0.10–0.86) higher systolic and diastolic blood pressure in early pregnancy, respectively, but not with blood pressure in later pregnancy. Also, maternal glucose concentrations were not associated with the risks of gestational hypertension or preeclampsia.

CONCLUSIONS

Maternal early-pregnancy non-fasting glucose concentrations within the normal range are associated with blood pressure in early pregnancy, but do not seem to affect placental hemodynamics and the risks of gestational hypertensive disorders.