bluuebunny/crossref_metadata_2025 huggingface dataset:
Computational density-functional approaches on finite-size and guest-lattice effects in CO2@sII clathrate hydrate
Authors: Cabrera-Ramírez Adriana , Yanes-Rodríguez Raquel , Prosmiti Rita
Published: January 2021

We performed first-principles computations to investigate guest–host/host–host effects on the encapsulation of the CO2 molecule in sII clathrate hydrates from finite-size clusters up to periodic 3D crystal lattice systems. Structural and energetic properties were first computed for the individual and first-neighbors clathrate-like sII cages, where highly accurate ab initio quantum chemical methods are available nowadays, allowing in this way the assessment of the density functional (DFT) theoretical approaches employed. The performance of exchange–correlation functionals together with recently developed dispersion-corrected schemes was evaluated in describing interactions in both short-range and long-range regions of the potential. On this basis, structural relaxations of the CO2-filled and empty sII unit cells yield lattice and compressibility parameters comparable to experimental and previous theoretical values available for sII hydrates. According to these data, the CO2 enclathration in the sII clathrate cages is a stabilizing process, either by considering both guest–host and host–host interactions in the complete unit cell or only the guest–water energies for the individual clathrate-like sII cages. CO2@sII clathrates are predicted to be stable whatever the dispersion correction applied and in the case of single cage occupancy are found to be more stable than the CO2@sI structures. Our results reveal that DFT approaches could provide a good reasonable description of the underlying interactions, enabling the investigation of formation and transformation processes as a function of temperature and pressure.
Power conversion efficiency prioritized AC filter inductor design for three-phase PWM inverter
Authors: Matsumori Hiroaki , Mizutani Daisuke , Kosaka Takashi , Matsui Nobuyuki , Miyazaki Tatsuya , Okawauchi Yuta
Published: January 2021

This study was conducted to develop a design method of power density and efficiency maximization for three-phase pulse-width modulated (PWM) inverters that include AC filter. A tradeoff relationship exists between power density and efficiency. In general, increasing the switching frequency is known to increase the switching device loss and decrease the volume of the passive components. A three-phase PWM inverters design should consider the balance between conversion efficiency and inverter volume. However, best of our knowledge, no practical study has focused on the optimal design of a three-phase PWM inverter that includes an AC filter. This is because the iron loss of the AC filter inductor changes in complicated ways depending on the DC-bias excitation, amplitude of switching ripple current, etc. Therefore, the present authors clarified this iron loss mechanism and realized a highly accurate iron loss calculation method in previous studies. In this paper, the relationship between efficiency and volume for the switching frequency was analyzed when the AC filter inductor was designed for minimal loss by adjusting the core diameter, height, and number of winding turns. The efficiency and volume optimization achieved by designing a proper inductor was verified via comparison with a base design.
On the adhesion–velocity relation and length adaptation of motile cells on stepped fibronectin lanes
Authors: Schreiber Christoph , Amiri Behnam , Heyn Johannes C. J. , Rädler Joachim O. , Falcke Martin
Published: January 2021

Significance

Cells exert forces on their environment by contracting actin networks, friction of intracellular F-actin flow, and polymerization when they move, e.g., during tumor metastasis or development. In this context, the relation between adhesion and cell velocity is a general cell-type-independent observation, the investigation of which bears the chance of understanding basic mechanisms. Restricting cell motion to one-dimensional lanes simplifies the problem and allows for comparison to mathematical models. Polymerization at the cell’s leading edge drives F-actin network flow and pushes the membrane. The drag of detaching the cell, the membrane, and the cell body resist motion. Since only velocity-controlled forces shape motion, cells can move even across highly adhesive areas without getting stuck.
Conjugative plasmid-encoded toxin–antitoxin system PrpT/PrpA directly controls plasmid copy number
Authors: Ni Songwei , Li Baiyuan , Tang Kaihao , Yao Jianyun , Wood Thomas K. , Wang Pengxia , Wang Xiaoxue
Published: January 2021

Significance

Since conjugative plasmids are usually large and may carry genes encoding functions that are detrimental to the bacterial host, minimizing plasmid copy number is critical for reducing the host burden. Toxin–antitoxin (TA) systems are one of the conserved modules on conjugative plasmids. Here, we demonstrate the functional significance of a large group of antitoxins on conjugative plasmids: the antitoxin acts as an unexpected player in the negative control of plasmid replication. For the plasmid-encoded PrpT/PrpA TA system, the antitoxin can control toxin production by binding to PrpT and by reducing plasmid copy number. This work shows that the antitoxin can directly regulate plasmid replication, expanding our understanding of the physiological role of TA systems.
The RNA helicase Dhx15 mediates Wnt-induced antimicrobial protein expression in Paneth cells
Authors: Wang Yalong , He Kaixin , Sheng Baifa , Lei Xuqiu , Tao Wanyin , Zhu Xiaoliang , Wei Zheng , Fu Rongjie , Wang Anlei , Bai Shengdan , Zhang Zhao , Hong Na , Ye Chao , Tian Ye , Wang Jun , Li Mingsong , Zhang Kaiguang , Li Lin , Yang Hua , Li Hua-Bing , Flavell Richard A. , Zhu Shu
Published: January 2021

Significance

RNA helicases play critical roles in multiple biological processes. However, little in vivo data are available because of the lethality of mice completely deficient in RNA helicases. Here, we generate mice with conditional knockout of DEAD-box Helicase 15 (Dhx15) in the intestine, in which we found a specific defect in antimicrobial peptide (AMP) α-defensins in Paneth cells. Additionally, we found that Dhx15-specific depletion in the intestine leads to susceptibility to enteric bacterial infection as well as dextran sulfate sodium-induced colitis in mice. In humans, we also found reduced protein levels of Dhx15 in ulcerative colitis patients.
Genome-wide CRISPR screens reveal multitiered mechanisms through which mTORC1 senses mitochondrial dysfunction
Authors: Condon Kendall J. , Orozco Jose M. , Adelmann Charles H. , Spinelli Jessica B. , van der Helm Pim W. , Roberts Justin M. , Kunchok Tenzin , Sabatini David M.
Published: January 2021

Significance

The mTORC1 eukaryotic cell growth regulator dynamically responds to changes in environmental nutrient levels. While many upstream regulators are known to modulate mTORC1 activity, the full complement of these is unknown. Here, using a genome-wide FACS-based CRISPR-Cas9 screen, we identify almost all known positive regulators of mTORC1 as well as many others. The results of our screens highlighted the importance of mitochondrial health in the regulation of mTORC1, which led us to investigate how mitochondrial stress impinges on mTORC1 signaling. Ultimately, we found that two kinases, AMPK and HRI, together signal mitochondrial distress to mTORC1. Furthermore, full inhibition of mTORC1 by mitochondrial stress requires the ATF4-dependent up-regulation of two mTORC1 pathway inhibitors, Sestrin2 and Redd1.
An ablative for the Greeks?
Authors: Rooy Raf Van
Published: January 2021

In this article, I discuss a grammar dispute that took place between Philipp Nicodemus Frischlin and Martin Crusius in
Tübingen in the winter of 1585/1586. I argue that their diverging views on the ablative case reflect a disagreement on two levels, in
addition to their obvious personal rivalry: (1) the foundations of grammar, which Frischlin based on meaning rather than form, following
J. C. Scaliger, and (2) contrasting attitudes toward the Greek people and heritage. Additionally, I discuss Frischlin’s views on the
article and the optative mood, while also tracing a popular misquote from Scaliger’s work to Frischlin.
Comparing lexical bundle use in EAP reading textbooks to lower-division university textbooks
Authors: Lynn Ethan M.
Published: January 2021

This study employed a corpus analysis to describe differences in lexical bundle patterns between English for academic purposes (EAP) reading textbooks and lower-division university textbooks by focusing on three characteristics: (1) the frequency of occurrence of bundles, (2) the frequency of bundle structures (e.g., phrasal vs. clausal), and (3) the frequency of bundle discourse functions (e.g., stance, discourse organizers, and referential; see Biber et al., 2004; Biber, 2006). Results revealed that the corpus representing lower-division university textbooks employed more passive bundles, intangible framing bundles, and text deixis bundles. On the other hand, the corpus representing EAP reading textbooks contained more prepositional phrase bundles, anticipatory it bundles, and place bundles. A qualitative comparison also revealed that quantity bundles in the corpus representing lower-division university textbooks made reference to technical and academic calculations. These results show how the communicative purposes of EAP reading textbooks differ from introductory university textbooks, which can be used to inform EAP reading instruction.
Clinical features of large vessel vasculitis (LVV): Elderly-onset versus young-onset
Authors: Morinaka Satoshi , Tsuboi Hiroto , Hagiwara Shinya , Sugita Toshiki , Tabuchi Daiki , Sato Ryota , Nishiyama Taihei , Okamoto Shota , Terasaki Toshihiko , Yagishita Mizuki , Takahashi Hiroyuki , Kondo Yuya , Matsumoto Isao , Sumida Takayuki
Published: January 2021

Objectives

We compared large vessel vasculitis (LVV) clinical features between age groups.

Methods

We retrospectively examined clinical features and therapies in 41 LVV patients at our hospital from January 2010 to March 2020. We compared two patient groups, elderly (≥50 years) and young (<50 years).

Results

Of all patients, 29 were elderly and 12 were young. In the younger group, upper extremity symptoms (p <.05), bruits (p <.01), and cardiovascular complications (p <.01) were more common. Of the elderly group, 7 (24%) met classification criteria for giant cell arteritis while none of the younger group met these criteria; however, 10 (83%) of the younger group and 3 (10%) of the elderly group met the ACR classification criteria for Takayasu arteritis (p <.01). In the elderly group, 16 patients (66%) met no criteria (p <.01). There were no significant differences in laboratory findings but imaging showed a significantly higher incidence of head and neck artery lesions in the younger group (p <.05). The younger group was more likely to receive additional tocilizumab (p <.01) and cardiovascular complications were more likely to occur in younger patients (p < .01).

Conclusion

LVV clinical features differed between elderly- and young-age-onset groups.
Classification theorem and properties of singular solutions to the Tolman–Oppenheimer–Volkoff equation
Authors: Anastopoulos Charis , Savvidou Ntina
Published: January 2021

The Tolman–Oppenheimer–Volkoff (TOV) equation admits singular solutions in addition to regular ones. Here, we prove the following theorem. For any equation of state that (i) is obtained from an entropy function, (ii) has positive pressure and (iii) satisfies the dominant energy condition, the TOV equation can be integrated from a boundary inwards to the center. Hence, the thermodynamic consistency of the EoS precludes pathological solutions in which the integration terminates at finite radius (because of horizons, or divergences / zeroes of energy density). At the center, the mass function either vanishes (regular solutions) or it is negative (singular solutions). For singular solutions, the metric at the center is locally isomorphic to negative-mass Schwarzschild spacetime. This means that matter is stabilized because the singularity is strongly repulsive. We show that singular solutions are causally well behaved: they are bounded-acceleration complete, and they are conformal to a globally hyperbolic spacetime with boundary. Finally, we show how to modify unphysical equations of state in order to obtain non-pathological solutions, and we undertake a preliminary investigation of dynamical stability for singular solutions.
Conditional STIRAP based on Rydberg blockade: entanglement fidelities in three- and four-level schemes
Authors: Cano Daniel
Published: January 2021

This paper investigates the generation of quantum entanglement by means of conditional stimulated Raman adiabatic passage (STIRAP) based on Rydberg blockade. The paper compares the entanglement fidelities in three-level and four-level schemes and analyzes the adiabatic conditions in both cases. In particular, Green–Horne–Zeilinger states can be deterministically generated in an atomic ensemble interacting with a single control atom.
The nuts and bolts of core-hole constrained ab initio simulation for K-shell x-ray photoemission and absorption spectra
Authors: Klein Benedikt P , Hall Samuel J , Maurer Reinhard J
Published: January 2021

X-ray photoemission (XPS) and near edge x-ray absorption fine structure (NEXAFS) spectroscopy play an important role in investigating the structure and electronic structure of materials and surfaces. Ab initio simulations provide crucial support for the interpretation of complex spectra containing overlapping signatures. Approximate core-hole simulation methods based on density functional theory (DFT) such as the delta-self-consistent-field (ΔSCF) method or the transition potential (TP) method are widely used to predict K-shell XPS and NEXAFS signatures of organic molecules, inorganic materials and metal–organic interfaces at reliable accuracy and affordable computational cost. We present the numerical and technical details of our variants of the ΔSCF and TP method (coined ΔIP-TP) to simulate XPS and NEXAFS transitions. Using exemplary molecules in gas-phase, in bulk crystals, and at metal–organic interfaces, we systematically assess how practical simulation choices affect the stability and accuracy of simulations. These include the choice of exchange–correlation functional, basis set, the method of core-hole localization, and the use of periodic boundary conditions (PBC). We particularly focus on the choice of aperiodic or periodic description of systems and how spurious charge effects in periodic calculations affect the simulation outcomes. For the benefit of practitioners in the field, we discuss sensible default choices, limitations of the methods, and future prospects.
Modeling, measurement, and calibration of three-axis integrated aerial camera pointing errors
Authors: Liu Hao , Zhou Xiaoqin , Liu Qiang , Ma Meng , He Xiuzhi , Lin Jieqiong
Published: January 2021

Aerial cameras are currently widely used in various fields. However, traditional aerial cameras have certain limitations. We propose a new three-axis integrated aerial camera that can significantly improve imaging efficiency. Both traditional aerial cameras and three-axis integrated aerial cameras suffer from reductions in image quality due to mechanical errors. In this paper, we analyze the influence of mechanical errors on pointing errors and establish a pointing parametric model (PM) based on spatial coordinate transformation and ray tracing. We also consider how the presence of nonlinear errors in aerial cameras affects image quality, and propose a semi-parametric model (SPM) to compensate for nonlinear errors. The PM and the SPM can be used to calibrate the pointing of aerial cameras. In addition, we propose an improved measurement method that can gauge the pointing errors that occur when the three-axis integrated aerial camera rotates to different angles. The results prove that both the PM and the SPM can effectively calibrate the pointing of the aerial camera. Following calibration using the SPM, the pointing errors were greatly reduced. The mean was reduced by more than two orders of magnitude, and the variance was reduced by 99.95%. The SPM completes the pointing calibration better than the PM.
An approximation method combined with conformal transformation for the fast measurement of blade section curves
Authors: Lu Zhongyang , Zhao Ji , Yang Xu , Qu Xingtian
Published: January 2021

To realize high-precision machining of free-form blade surfaces, it is necessary to measure and reconstruct the blade morphology several times. Sampling measurements and data compression through free-curve approximation technology are of great benefit in shortening the processing time. A novel B-spline approximation method is proposed in this paper, which can determine a few dominant points based on curvature characteristics to approximate dense and noisy measured points with high precision. We adopt a unique adaptive knot placement strategy combined with a curvature dependent evaluation parameter and a conformal transformation method. This strategy is error-bounded in the initial knot placement, which greatly reduces the time consumed by subsequent iterative insertions. The proposed method shows advantages in approximation accuracy, compression rate, and especially in computational efficiency, in comparison with four traditional knot placement methods. Experiments were carried out and the results show that the dominant point selected by this method can replace the fine measurement results, and the compression rate of the measurement points can reach more than 90%. This method is suitable for the sampling measurement and compression of the data of blades, aircraft wings, and other similar free-form surfaces, and is especially suitable for solving the inefficiency problem caused by repeated measurements made in the process of iterative machining of aero-engine blades.
Packaging and high-temperature characterization of a 650 V, 150 A eGaN HEMT
Authors: Lu Shengchang , Burgos Rolando , Lu Guo-Quan
Published: January 2021

Among the salient features of gallium nitride (GaN) power semiconductor devices is their high-temperature capability. However, commercial GaN devices, such as the high-electron-mobility transistors (HEMTs), are limited to 125 °C junction-temperature operation because of their packaging. To explore the high-temperature capability of GaN power devices, a commercial 650 V, 150 A enhancement-mode GaN HEMT chip was packaged by silver-sintering die-bonding on direct-bond-copper substrate and encapsulation in a high-temperature polymer enclosure filled with nitrogen. Static characteristics of the packaged GaN device were measured at temperatures up to 250 °C. The threshold voltage of the transistor at 250 °C decreased to around 0.9 V, about 30% lower than that at room temperature. At temperatures beyond 150 °C, the saturation current fell sharply below the rated current, resulting in a rapid rise in the on-resistance versus current. At 250 °C, the saturation current decreased rapidly to around 67 A, <45% of the rated current. The reverse leakage also increased sharply at temperatures beyond 150 °C. Although the packaged device was operational at 250 °C, one would need to significantly lower the expectations for its performance and address the challenges of packaging and thermal management if it were to be used in a high-temperature power converter.
A compact high frequency voltage amplifier for superconductor–semiconductor logic interface
Authors: Razmkhah Sasan , Bozbey Ali , Febvre Pascal
Published: January 2021

The many advantages of cryogenically cooled single-flux quantum (SFQ) circuits imply that the high speed and low voltage output signals must be amplified and interfaced with standard electronics. State-of-the-art low-noise and wide-band amplifiers are required to interface with room temperature electronics. One solution is to place preamplifiers at the cryogenic stage, which requires specific semiconductor design and fabrication. However, a more viable and energy-efficient approach is to integrate the pulsed logic circuit output stages with on-chip superconductor preamplifiers. We designed, fabricated, and tested an on-chip compact voltage multiplier integrated with the output stage of SFQ circuits to increase the voltage amplitude of SFQ pulses. The circuit is designed with the same technology as the logic circuit hence its noise level is lower, and it works at higher frequencies compared to complementary metal-oxide semi-conductor amplifiers and due to quantized nature of it there is no added noise. The fabricated circuit has a compact size of 160 µm × 320 µm and provides about 10 dB gain with measured 600 µV output voltage at frequencies up to ∼25 GHz in simulations. By stacking more levels, over 20 dB gain at circuit level is achievable as shown in simulations. Moreover the gain of the superconductor voltage amplifier is quantized and programmable.
A Grover-search based quantum learning scheme for classification
Authors: Du Yuxuan , Hsieh Min-Hsiu , Liu Tongliang , Tao Dacheng
Published: January 2021

The hybrid quantum–classical learning scheme provides a prominent way to achieve quantum advantages on near-term quantum devices. A concrete example toward this goal is the quantum neural network (QNN), which has been developed to accomplish various supervised learning tasks such as classification and regression. However, there are two central issues that remain obscure when QNN is exploited to accomplish classification tasks. First, a quantum classifier that can well balance the computational cost such as the number of measurements and the learning performance is unexplored. Second, it is unclear whether quantum classifiers can be applied to solve certain problems that outperform their classical counterparts. Here we devise a Grover-search based quantum learning scheme (GBLS) to address the above two issues. Notably, most existing QNN-based quantum classifiers can be seamlessly embedded into the proposed scheme. The key insight behind our proposal is reformulating the classification tasks as the search problem. Numerical simulations exhibit that GBLS can achieve comparable performance with other quantum classifiers under various noise settings, while the required number of measurements is dramatically reduced. We further demonstrate a potential quantum advantage of GBLS over classical classifiers in the measure of query complexity. Our work provides guidance to develop advanced quantum classifiers on near-term quantum devices and opens up an avenue to explore potential quantum advantages in various classification tasks.
Absorption interferometer of two-sided cavity*
Authors: Guo Miao-Di , Li Hong-Mei
Published: January 2021

We propose a scheme in which an arbitrary incidence can be made perfectly reflected/transmitted with a phase modulator. We analyze the variation of intracavity field as well as output field with closed-loop phase ϕ
1 of the control fields and relative phase ϕ
2 of the probe beams. With two phases, medium absorption and light interference can be controlled so that photon escape from the cavity can be manipulated, thus an intensity switching based on phase modulation can be realized. And the condition for perfect transmitter or reflector is obtained. Then based on the transmission/reflection analysis, the total absorption of this system can be investigated. Therefore our scheme can be used as an absorption interferometer to explore the optical absorption in some complicated system. The state delay of the output light intensity, which is dependent on ϕ
1 or ϕ
2, can be applied in the realization of quantum phase gate and subtle wave filter. And based on this scheme, we implement the state transfer between perfect transmitter/reflector and non-perfect coherent photon absorber via relative-phase modulation.
Diagonal reflection symmetries and universal four-zero texture *
Authors: Yang Masaki J. S.
Published: January 2021

In this paper, we consider a set of new symmetries in the SM: diagonal reflection symmetries

with

diag

. These generalized

symmetries predict the Majorana phases to be

or

. Realization of diagonal reflection symmetries implies a broken chiral

symmetry only for the first generation. The axion scale is suggested to be

[GeV]. By combining the symmetries with the four-zero texture, the mass eigenvalues and mixing matrices of quarks and leptons are reproduced well. This scheme predicts the normal hierarchy, the Dirac phase

and

or

[meV]. In this scheme, the type-I seesaw mechanism and a given neutrino Yukawa matrix

completely determine the structure of the right-handed neutrino mass

. A

unification predicts the mass eigenvalues to be

[GeV].
Cost optimization of a rectangular singly reinforced concrete beam by Generalized Reduced Gradient method
Authors: Markandeya Raju P , Manasa A , Rohini G
Published: January 2021

Cost Optimization of a singly reinforced rectangular beam using GRG method is presented in this paper. The objective function is chosen as the overall cost of the beam given by the sum of the products of unit rates of steel and concrete in rupees per unit volume (m
3) with their volumes. 28 combinations of simply supported beams of different spans subjected to different point loads and uniformly distributed loads are analyzed using EXCEL Solver. The constraints are adopted to satisfy various guidelines as per IS 456:2000 code of practice.
Influence of glass fibres in stone mastic asphalt
Authors: Udaya Bhanu V , Pavan Kumar NVLN
Published: January 2021

The study in this paper examines the effect of fibres on the stability of Stone Mastic Asphalt (SMA) mixture in flexible pavement. Two types of fibres namely Class-C Glass fibres(Glass – C), and Alkali Resistant Glass Fiber(ARGF) were used in this investigation. From the results, it was found that the addition of glass fibres showed the improvement in the properties of the stone mastic asphalt mix. The addition of fibres at 0.4% with 6% binder content results in increased stability values and low draindown values.
Change detection analysis in LULC of the upstream Thandava reservoir using RS and GIS applications
Authors: Ramanamurthy B V , Vijayasaradhi B
Published: January 2021

Change detection is a time series process to analyze Land use/land cover (LU/LC) changes within a specific period. This analysis will help to take the necessary decisions for policymakers. In this study for this purpose, we collect the data in the form of topographical maps from Survey of India (SOI), Satellite remote sensing data from USGS (United States Geological Survey) and software like Arc GIS 10.3 and ERDAS IMAGINE 2014 were used for analyzing the data between the periods of 1995-2008, 2008-2020 and 1995-2020. The study area was classified into eight land use and land cover categories based on the most likelihood classified approach and quantifying the changes in the above mentioned period time. It was observed that the forest area has vanished and barren land was increased during 1995-2020.
Various resonance lineshapes available in a single microring resonator
Authors: Xu Yameng , Li Jiaxuan , Kong Mei
Published: January 2021

To accommodate different application requirements, resonances of microring resonator (MRR)-based devices have been developed into various lineshapes, such as electromagnetically induced transparency, electromagnetically induced absorption, and Fano lineshapes. However, these lineshapes are mainly achieved in large-footprint structures demanding precise control. Under such context, this work investigates the formation of various resonance lineshapes in a single MRR with two partially reflecting elements incorporated into the bus waveguide. The transfer matrix model of the compact structure is established with the reflective wave in the MRR included. It is revealed that the abundant resonance lineshapes originate from the mode-coupling between the Fabry–Perot cavity and the MRR. Based on this model, the formation of each resonance lineshape is analyzed. The conditions under which each resonance lineshape can occur are identified and the characteristics of these resonance lineshapes are studied. In addition, the significant role of the reflective wave in the formation of these lineshapes is emphasized. Under the theoretical guidance of the presented work, various resonance lineshapes can be achieved and designed flexibly in a single MRR. Thus, the lineshapes required for a range of applications can be realized in a simple and reproducible MRR.
Analysis of anapole resonators in low index materials
Authors: Damaso Nicholas Joel , White Simon J U , Kim Sejeong
Published: January 2021

Photonic cavities are valued in current research owing to the multitude of linear and nonlinear effects arising from densely confined light. Cavity designs consisting of low loss dielectric materials can achieve significant light confinement. Until now, the basic concepts in all-dielectric photonics such as anapole resonances have been primarily studied in high index materials. Here, we use photonic simulation to propose fabricable designs for higher confinement in low index dielectric cavities by incorporating the extensively studied isolated dielectric nanodisk into broader host structures. We further discuss on hexagonal boron nitride nanodisks for their potential use in quantum and nanophotonics applications.
Effect of support material on the electrocatalytic activity of palladium Nanoparticle toward hydrogen evolution reaction
Authors: Woldetinsay Mengistu , Soreta Tesfaye R , Maiyalagan Thandavarayan , Femi Olu Emmanuel
Published: January 2021

Support materials are very crucial in noble metal electrocatalyst synthesis. They improve the catalytic activity of the noble metal by increasing their conductivity, surface area, and interactions. This report investigates the effect of support material on palladium nanoparticles’ electrochemical activity towards hydrogen evolution reaction. The structural and morphological study was conducted using x-ray diffraction (XRD), Raman Spectroscopy, and Field Emission Scanning Electron Microscope (FE-SEM) that confirmed the support material has a significant effect on the structure of nanocomposite. The hydrogen evolution (HER) performance of the synthesized electrocatalyst was evaluated in 0.5 M H2SO4. The Pd-Ni/g-C3N4 has higher catalytic activity with a lower overpotential of 55 mV at 10 mA cm2 current density and Tafel slope value 56 mV.dec−1 than other support material studied. The overpotential at 10 mA cm2 and Tafel slope value for electrocatalyst studied respectively are:- Pd/MoS2/CB( 78 mV at 10 mA cm2 and 57 mV.dec−1), Pd/g-C3N4(105 mV at 10 mA cm2 and 69 mV.dec−1) and Pd/CB(117 mV at 10 mA cm2 and 68 mV.dec−1). The impedance spectroscopy study shows Pd-Ni/g-C3N4 demonstrated the smallest semicircle. Further, the Chronoamparometry(CP) and linear sweep voltammetry (LSV) stability study of the highest performing electrocatalyst demonstrates negligible loss in current density for 12 h and minor change in the polarization curve after10,000 cycles. This study shows how the support material influences noble metal catalysts’ activity and stability via the support- metal interactions.
Thermotropic liquid crystals with low-dimensional carbon allotropes
Authors: Draude Adam P , Dierking Ingo
Published: January 2021

As display devices based on liquid crystals have matured over the last decades, liquid crystal research has shifted its priorities in slightly different directions, such as sensors, photonics, nanotechnology and even more biologically related fields like drug delivery. This implied a change of emphasis in the development of novel materials, of which a completely new class of liquid crystal based composites emerged, that of nanoparticle-dispersed liquid crystals. The underlying ideas were to add functionality, while maintaining switchability, and the exploitation of liquid crystal self-organisation to build hierarchical nanostructures. Of particular interest for applications are dispersions of carbon nanomaterials, such as fullerenes, nanotubes and the graphene variants, due to their interactions with conventional liquid crystals. While such systems have been investigated for the past two decades, we concentrate in this review on the effects of dimensionality of the dispersed carbon nanoparticles, which goes hand in hand with the more recent developments in this field. Examples are the doping of 0D fullerenes in liquid crystals and implications for Blue Phase stability, or 1D nanotubes in nematic and ferroelectric liquid crystals, questions of dispersibility and applications as alignment media in ITO-free devices. Graphene (2D) and especially graphene oxide are mainly investigated for their formation of lyotropic liquid crystals. We here discuss the more recent aspects of dispersion in thermotropics.
Crowther, Samuel Ajayi
Authors: Oduntan Oluwatoyin
Published: January 2021

The case for narrating the history of slavery and emancipation through the biography of enslaved Africans is strongly supported by the life and experiences of Samuel Ajayi Crowther (1806–1891). Kidnapped into slavery in 1821, recaptured and settled in Sierra Leone in 1822, he became a missionary in 1845, founder of the Niger mission in 1857, and Bishop of the Niger Mission in 1864. His life and career covered the span of the 19th century during which revolutionary forces like jihadist revolutions, the abolition of the slave trade, the rise of a new Westernized elite, and European colonization created the roots of the modern state system in West Africa. He was intricately tied to the Christian Missionary Society (CMS), Britain’s antislavery evangelical movement, resulting in Ajayi becoming the poster face of slavery, its acclaimed product of abolitionism, the preeminent advocate of evangelical emancipation, and the organizer of practical emancipation in West Africa. The leader of a very small group of Africans who worked diligently against the slave trade and domestic slavery, Ajayi also became a victim of the use of that agenda by imperialists. Thus, the contrasts of his life (i.e., slavery/freedom, nationalist/hybrid, preacher/investor, leader/weakling, linguist/literalist, etc.) were celebrated by himself, his patrons, and his evangelical followers on one hand, and denounced by his critics on the other. They underline the disagreements over his legacy, and indeed over the understanding of the institution of slavery, abolition, and emancipation in West Africa.
Multimodal Image Analysis of Apparent Brain Age Identifies Physical Fitness as Predictor of Brain Maintenance
Authors: Dunås Tora , Wåhlin Anders , Nyberg Lars , Boraxbekk Carl-Johan
Published: January 2021

Maintaining a youthful brain structure and function throughout life may be the single most important determinant of successful cognitive aging. In this study, we addressed heterogeneity in brain aging by making image-based brain age predictions and relating the brain age prediction gap (BAPG) to cognitive change in aging. Structural, functional, and diffusion MRI scans from 351 participants were used to train and evaluate 5 single-modal and 4 multimodal prediction models, based on 7 regression methods. The models were compared on mean absolute error and whether they were related to physical fitness and cognitive ability, measured both currently and longitudinally, as well as study attrition and years of education. Multimodal prediction models performed at a similar level as single-modal models, and the choice of regression method did not significantly affect the results. Correlation with the BAPG was found for current physical fitness, current cognitive ability, and study attrition. Correlations were also found for retrospective physical fitness, measured 10 years prior to imaging, and slope for cognitive ability during a period of 15 years. The results suggest that maintaining a high physical fitness throughout life contributes to brain maintenance and preserved cognitive ability.
Characteristics ofSalmonellaRecovered From Stools of Children Enrolled in the Global Enteric Multicenter Study
Authors: Kasumba Irene N , Pulford Caisey V , Perez-Sepulveda Blanca M , Sen Sunil , Sayed Nurulla , Permala-Booth Jasnehta , Livio Sofie , Heavens Darren , Low Ross , Hall Neil , Roose Anna , Powell Helen , Farag Tamer , Panchalingham Sandra , Berkeley Lynette , Nasrin Dilruba , Blackwelder William C , Wu Yukun , Tamboura Boubou , Sanogo Doh , Onwuchekwa Uma , Sow Samba O , Ochieng John B , Omore Richard , Oundo Joseph O , Breiman Robert F , Mintz Eric D , O’Reilly Ciara E , Antonio Martin , Saha Debasish , Hossain M Jahangir , Mandomando Inacio , Bassat Quique , Alonso Pedro L , Ramamurthy T , Sur Dipika , Qureshi Shahida , Zaidi Anita K M , Hossain Anowar , Faruque Abu S G , Nataro James P , Kotloff Karen L , Levine Myron M , Hinton Jay C D , Tennant Sharon M
Published: January 2021

Background

The Global Enteric Multicenter Study (GEMS) determined the etiologic agents of moderate-to-severe diarrhea (MSD) in children under 5 years old in Africa and Asia. Here, we describe the prevalence and antimicrobial susceptibility of nontyphoidal Salmonella (NTS) serovars in GEMS and examine the phylogenetics of Salmonella Typhimurium ST313 isolates.

Methods

Salmonella isolated from children with MSD or diarrhea-free controls were identified by classical clinical microbiology and serotyped using antisera and/or whole-genome sequence data. We evaluated antimicrobial susceptibility using the Kirby-Bauer disk-diffusion method. Salmonella Typhimurium sequence types were determined using multi-locus sequence typing, and whole-genome sequencing was performed to assess the phylogeny of ST313.

Results

Of 370 Salmonella-positive individuals, 190 (51.4%) were MSD cases and 180 (48.6%) were diarrhea-free controls. The most frequent Salmonella serovars identified were Salmonella Typhimurium, serogroup O:8 (C2-C3), serogroup O:6,7 (C1), Salmonella Paratyphi B Java, and serogroup O:4 (B). The prevalence of NTS was low but similar across sites, regardless of age, and was similar among both cases and controls except in Kenya, where Salmonella Typhimurium was more commonly associated with cases than controls. Phylogenetic analysis showed that these Salmonella Typhimurium isolates, all ST313, were highly genetically related to isolates from controls. Generally, Salmonella isolates from Asia were resistant to ciprofloxacin and ceftriaxone, but African isolates were susceptible to these antibiotics.

Conclusions

Our data confirm that NTS is prevalent, albeit at low levels, in Africa and South Asia. Our findings provide further evidence that multidrug-resistant Salmonella Typhimurium ST313 can be carried asymptomatically by humans in sub-Saharan Africa.
Normal Times? (Pluri-)Temporality in Everyday Life in Imperial Germany around 1900
Authors: Rothauge Caroline
Published: January 2021

On an international level, temporal standardization was increasingly discussed in the last third of the nineteenth century, but how exactly it was defined and implemented in everyday life in late Imperial Germany has awaited investigation. This article comprises three examples that show how administrative attempts to denominate and institutionalize certain homogeneous concepts of time were dealt with in Germany on a practical basis around 1900. Drawing on both archival material and printed sources, the first example analyses temporal semantics in the public sphere and explains the boom in ‘normal’ times; the second example looks at how distributing normal time signals became a trade and, thus, a contested service; and the last example focuses on discussions and conflicts around the introduction of unified working times, especially in the industrial firm Siemens & Halske. The findings presented in this article show that, initially, introducing abstract concepts of normal times in different sectors of life paradoxically did not standardize the ways people understood and used time but rather further pluralized them. Thus, the processes of regulating and reforming pluritemporality in Imperial Germany were far from complete by the end of the century. The article offers a perspective on contemporaries as actors involved in a complex plurality of modernization efforts and projects, including temporal (self-)definitions and arrangements. By historicizing ‘time’ proper in late Imperial Germany, it contributes to the temporal turn, since it provides empirical evidence about how today’s standard time regimes emerged.
Density of States and Delocalization for Discrete Magnetic Random Schrödinger Operators
Authors: Becker Simon , Han Rui
Published: January 2021

We study discrete magnetic random Schrödinger operators on the square and honeycomb lattice. For the non-random magnetic operator on the hexagonal lattice with any rational magnetic flux, we show that the middle two dispersion surfaces exhibit Dirac cones. We then derive an asymptotic expansion for the density of states on the honeycomb lattice for oscillations of arbitrary rational magnetic flux. This allows us, as a corollary, to rigorously study the quantum Hall effect and conclude dynamical delocalization close to the conical point under disorder. We obtain similar results for the discrete random Schrödinger operator on the $\mathbb Z^2$-lattice with weak magnetic fields, close to the bottom and top of its spectrum.
Factors influencing decision making for implementing e-health in light of the COVID-19 outbreak in Gulf Cooperation Council countries
Authors: Al-Anezi Fahad M
Published: January 2021

Background

Electronic health (e-health) approaches such as telemedicine, mobile health, virtual healthcare and electronic health records are considered to be effective in increasing access to healthcare services, reducing operational costs and improving the quality of healthcare services during the coronavirus disease 2019 (COVID-19) outbreak, a pandemic resulting from the spread of a novel coronavirus discovered in December 2019. In this context, the aim of this study was to identify the most important factors influencing decision making on the implementation of e-health in Gulf Cooperation Council (GCC) member states (Bahrain, Kuwait, Oman, Qatar, Saudi Arabia and the United Arab Emirates), which are in the process of digitizing healthcare services.

Methods

This study reviewed the literature to identify the important factors influencing decision making on e-health. In addition, a questionnaire-based survey was conducted in order to identify the most important criteria to be considered in decision making on e-health. The survey link was forwarded to 978 healthcare practitioners and 42 experts (purposive sampling), from which a final sample of 892 (864 practitioners and 28 experts) was achieved, reflecting a response rate of 87.45%.

Results

Of the 44 factors identified under seven themes (strategic, quality, management, technology, function characteristics, economic, sociocultural and demographic factors), 22 factors were identified to be the most important criteria.

Conclusions

Findings from this study suggest that decision making in relation to e-health is a complex process that requires consideration of various factors. It was also found that attention should be paid to sociocultural and demographic factors, which may need to be considered in increasing healthcare access during the COVID-19 outbreak.
A hot mini-Neptune in the radius valley orbiting solar analogue HD 110113
Authors: Osborn H P , Armstrong D J , Adibekyan V , Collins K A , Delgado-Mena E , Howell S B , Hellier C , King G W , Lillo-Box J , Nielsen L D , Otegi J F , Santos N C , Ziegler C , Anderson D R , Briceño C , Burke C , Bayliss D , Barrado D , Bryant E M , Brown D J A , Barros S C C , Bouchy F , Caldwell D A , Conti D M , Díaz R F , Dragomir D , Deleuil M , Demangeon O D S , Dorn C , Daylan T , Figueira P , Helled R , Hoyer S , Jenkins J M , Jensen E L N , Latham D W , Law N , Louie D R , Mann A W , Osborn A , Pollacco D L , Rodriguez D R , Rackham B V , Ricker G , Scott N J , Sousa S G , Seager S , Stassun K G , Smith J C , Strøm P , Udry S , Villaseñor J , Vanderspek R , West R , Wheatley P J , Winn J N
Published: January 2021

We report the discovery of HD 110113 b (TESS object of interest-755.01), a transiting mini-Neptune exoplanet on a 2.5-d orbit around the solar-analogue HD 110113 (Teff = 5730 K). Using TESS photometry and High Accuracy Radial velocity Planet Searcher (HARPS) radial velocities gathered by the NCORES program, we find that HD 110113 b has a radius of 2.05 ± 0.12  R⊕ and a mass of 4.55 ± 0.62  M⊕. The resulting density of $2.90^{+0.75}_{-0.59}$  g cm−3 is significantly lower than would be expected from a pure-rock world; therefore HD 110113 b must be a mini-Neptune with a significant volatile atmosphere. The high incident flux places it within the so-called radius valley; however, HD 110113 b was able to hold on to a substantial (0.1–1 per cent) H–He atmosphere over its ∼4 Gyr lifetime. Through a novel simultaneous Gaussian process fit to multiple activity indicators, we were also able to fit for the strong stellar rotation signal with period 20.8 ± 1.2  d from the RVs and confirm an additional non-transiting planet, HD 110113 c, which has a mass of 10.5 ± 1.2  M⊕ and a period of $6.744^{+0.008}_{-0.009}$  d.
Were Ancestral Proteins Less Specific?
Authors: Wheeler Lucas C , Harms Michael J
Published: January 2021

Some have hypothesized that ancestral proteins were, on average, less specific than their descendants. If true, this would provide a universal axis along which to organize protein evolution and suggests that reconstructed ancestral proteins may be uniquely powerful tools for protein engineering. Ancestral sequence reconstruction studies are one line of evidence used to support this hypothesis. Previously, we performed such a study, investigating the evolution of peptide-binding specificity for the paralogs S100A5 and S100A6. The modern proteins appeared more specific than their last common ancestor (ancA5/A6), as each paralog bound a subset of the peptides bound by ancA5/A6. In this study, we revisit this transition, using quantitative phage display to measure the interactions of 30,533 random peptides with human S100A5, S100A6, and ancA5/A6. This unbiased screen reveals a different picture. While S100A5 and S100A6 do indeed bind to a subset of the peptides recognized by ancA5/A6, they also acquired new peptide partners outside of the set recognized by ancA5/A6. Our previous work showed that ancA5/A6 had lower specificity than its descendants when measured against biological targets; our new work shows that ancA5/A6 has similar specificity to the modern proteins when measured against a random set of peptide targets. This demonstrates that altered biological specificity does not necessarily indicate altered intrinsic specificity, and sounds a cautionary note for using ancestral reconstruction studies with biological targets as a means to infer global evolutionary trends in specificity.