bluuebunny/crossref_metadata_2025 huggingface dataset:
The Effect of Bionic Brake Drum Striped Unit Body on Friction and Wear of Brake Pad
Authors: Hu Haiyan , Yang Haiyang , Yang Jiandong , Wang Qingnian , Zhou Ti
Published: December 2020

In this paper, the contact mechanics is applied to analyse the interaction between the striped unit body on the bionic brake drum and the brake pad. The contact stress distribution law of two objects interaction is obtained. According to the stress distribution law the change of the friction and wear of the striped unit body on the brake pad is derived. Considering the change of the surface feature regardless of other factors, the friction wear of the striped unit body on the brake pad has increased by more than 27%. It is found that small convex striped unit bodies are added on the surface of the bionic brake drum, which makes the contact surface between the brake drum and the brake pad no longer the original plane contact. Therefore, the pressure and direction between the contact surfaces are various. Besides, even if the external pressure does not change, the contact normal pressure between the contact surfaces will be increased which increases the friction wear on the brake pad accordingly.
Stress Concentration Factors for Multi-planar Tubular Joints Subjected to Axial Loading
Authors: Zhou Kai , Zuo Jingjing , Wang Wenhua , Bao Shiliu
Published: December 2020

The support structure for an offshore wind turbine is subjected to combined hydrodynamic loads and aerodynamic loads. The tubular joints are the weakest component leading to fatigue failure of the whole structure. Based on the multi-pile foundation structure which is used widely in China, the typical threeplanar tubular Y-joints is selected to study stress concentration factor (SCF). Then, the load types subjected to axial loadings of three-planar tubular Y-joints are determined. The finite element models of three-planar tubular Y-joints are established and used to calculate hot spot stresses. The stress concentration factors along the weld of the three-planar tubular Y-joints under the axial forces are obtained. The effects of geometrical parameters on SCFs are studied.
Research on the Method of Power Grid Equipment Material Price Forecast Based on Grey Theory
Authors: Shi Xiaoshuai , Zhang Tiankun , Li Gang , Zhang Junhui , Ni Yong , Chen Chao
Published: December 2020

The purchase cost of equipment and materials occupies a large proportion in the cost of power grid technical renovation and overhaul projects, and has a greater impact on project cost control. Therefore, improving the scientificity of equipment and material price forecasting methods is of great significance for controlling the cost of technical renovation and overhaul projects. This article takes the tower Q345 as the research object, and builds a prediction model based on gray theory based on the analysis of the company’s current tower price prediction methods and prediction effects. Through empirical verification, the model can effectively improve the accuracy of equipment material price prediction.
Application of Tissue Engineering in Tooth: A Review on Recent Trends and Advances
Authors: Chen Zeyu
Published: December 2020

Tooth loss has endangered human health for thousands of years, and people can apply dentures or dental implants to restore tooth loss today. Tissue engineering provides a novel way to regenerate a new functional tooth in vivo or vitro to help patients regain masticatory function and appearance. In this summarize review, we will discuss some promising seed cells in dental tissue engineering, the scaffolds that can be used to regenerate teeth, and some growth factors which can promote the development of tooth. Although significant progresses have been made nowadays, some challenges still remain. Hence, tissue engineering could be a choice to replace missing tooth in the future when the obstacles are solved.
A COMBINED USE OF FDM AND DOE METHOD TO DERIVE A NEW TRANSIENT SIMPLIFIED SEMI-ANALYTICAL MODEL: A CASE STUDY OF ANHYDRITE RADIANT SLAB
Authors: Merabtine Abdelatif , Kheiri Abdelhamid , Mokraoui Salim
Published: December 2020

Radiant floor heating systems (FHS) are considered as reliable heating systems since they ensure maintaining inside air temperature and reduce its fluctuations more efficiently than conventional heating systems. The presented study investigates the dynamic thermal response of an experimental FHS equipped with an anhydrite radiant slab. A new simplified model based on an analytical correlation is proposed to evaluate the heating radiant slab surface temperature and examine its thermal behavior under dynamic conditions. In order the validate the developed analytical model, an experimental scenario, under transient conditions, was performed in a monitored full-scale test cell. 2D and 3D numerical models were also developed to evaluate the accuracy of the analytical model. The method of Design of Experiments (DoE) was used to both derive meta-models, to analytically estimate the surface temperature, and perform a sensitivity study.
Impact of QW coupling on the binding energy in InGaN/GaN under the effects of the size, the impurity and the internal composition
Authors: Belaid Walid , El Ghazi Haddou , Zorkani Izeddine , Jorio Anouar
Published: December 2020

In the present paper, the binding energy of hydrogenic shallow-donor impurity in simple and double coupled quantum wells based on unstrained wurtzite (In,Ga)N/GaN is investigated. Considering the effective-mass and dielectric mismatches between the well and its surrounding matrix, the numerical calculations are performed within the framework of the parabolic band and the single band effective-mass approximations under the finite potential barrier using finite element method (FEM). According to our results, it appears that the main effect of the wells coupling is to enhance the binding energy. It is also obtained that the binding energy is strongly sensitive to the internal and external parameters and can be adjusted by the quantum well/barrier width, the impurity position and the internal Indium composition. Our results are in good agreement with the finding especially for those obtained by the variational approach.
Effect of Coupling Radiation Convection on Heat Transfer in the air gap of a Solar Collector
Authors: Ferahta Fatima Zohra , Abid Cherifa
Published: December 2020

In order to study the effect of convection-radiation coupling occurring in the air gap of a solar thermal collector, numerical simulations were conducted for various thicknesses of the air gap with and without radiation. The studied geometry is a closed cavity which represents the confined space between the absorber and the glass. The cavity is inclined at an angle equal to 45 ° and is uniformly heated from below. The flow is three-dimensional and in unsteady state. First, the simulations were conducted considering only convection in the air gap, in this case the radiation is neglected and in a second time, the coupling between convection and radiation was taken onto account. In the first case the results show that the increase of the air-gap thickness leads to an intensification of the natural convection which develops from laminar, chaotic to turbulent regime. When the radiation is taken into account, the results show that the flow regimes are substantially modified, the convection-radiation coupling reduces the temperature of the hot wall, which contributes to the reduction of the intensity of natural convection in the cavity. This observation is verified by the evolution of the temperature field at the absorber and the heat exchange coefficient. So in conclusion, this study allowed us to see the evolution of heat transfer in the air layer between the glass and the absorber, in the absence and in the presence of radiation. Taking into account the radiation in the cavity is essential for the modeling of flows in a cavity (which is often neglected).
COP enhancement and comparison of different absorption cooling systems
Authors: Ben Zid Nihel , Hajji Nejib , El Ganaoui Mohamed
Published: December 2020

The absorption refrigeration machines represent a good alternative to compression refrigeration machines but the major problem of this type of refrigeration lies in the COP, which seems to be less efficient. Several researches are carried out to improve the performances of these machines such as the combination with the technology of the ejectors. In this work, we are interested in the three ammonia-water absorption cycles: Single effect absorption, Ejector-absorption and Combined ejector-flash tank absorption cycles. A gas-gas ejector would be installed between the generator and the condenser. We suppose that adding a flash tank between the condenser and the evaporator could help improve the entrainment ratio of the ejector. We used simulations in order to compare the performances of these three different cycles. The simulation results demonstrate that the combined ejector-flash tank absorption cycle performs better than others.
Effect of glass powder and silica fume on mechanical properties and on alkali-silica reaction of recycled glass mortars
Authors: Douaissia Zineb , Merzoud Mouloud , Benazzouk Amar
Published: December 2020

In order to value glass in the production of cement and concrete. We have verified the effect of the progressive substitution of 10% to 50% of the volume of cement by glass powder and silica fume on the mechanical properties of hardened mortars, we have also verified their inhibitory effect of the Alkali Silica Reaction (ASR) by studying the variation of mass, expansion, opening and density of cracks as well as the loss of mechanical performance of mortars undergoes a test that accelerates the ASR by autoclave. We have concluded that the use of these mineral admixtures can improve the mechanical performance of mortars, and it can reduce expansions and mechanical performance losses due to ASR.
Management of Large Focal Chondral and Osteochondral Defects in the Knee
Authors: Calcei Jacob G. , Ray Taylor , Sherman Seth L. , Farr Jack
Published: December 2020

Large, focal articular cartilage defects of the knee (> 4 cm2) can be a source of significant morbidity and often require surgical intervention. Patient- and lesion-specific factors must be identified when evaluating a patient with an articular cartilage defect. In the management of large cartilage defects, the two classically utilized cartilage restoration procedures are osteochondral allograft (OCA) transplantation and cell therapy, or autologous chondrocyte implantation (ACI). Alternative techniques that are available or currently in clinical trials include a hyaluronan-based scaffold plus bone marrow aspirate concentrate, a third-generation autologous chondrocyte implant, and an aragonite-based scaffold. In this review, we will focus on OCA and ACI as the mainstay in management of large chondral and osteochondral defects of the knee. We will discuss the techniques and associated clinical outcomes for each, while including a brief mention of alternative treatments. Overall, cartilage restoration techniques have yielded favorable clinical outcomes and can be successfully employed to treat these challenging large focal lesions.
Surgical Leadership Training beyond the Traditional Mentorship Model
Authors: Saha Shivangi
Published: December 2020

In this article, I reflect on my experience of being awarded the International Resident Travel Scholarship for “Plastic Surgery the Meeting 2019.” I was the first Indian to be awarded the scholarship, and it offered me not only monetary assistance but also mentorship for future leadership positions. The award further opened doors for several future opportunities in the form of memberships in the American Society of Plastic Surgery (ASPS) committees and Resident Advisory Board of the prestigious “Plastic and Reconstructive Surgery Journal.” I believe this article will make more residents aware and utilize such opportunities for their career development.
Fabricating Flaps in the Forearm Prior to Tracheal Reconstruction
Authors: Biswas Gautam , Panchal Karnav Bharat , Jain Prateek V. , Manikantan Kapila , Sharan Rajeev , Arun Pattatheyil
Published: December 2020

Background The process of reconstruction of tracheal defects is complex and still not optimum. Options range from using staged reconstructions, combining flaps with autologous or alloplastic implants, as well as use of tissue-engineered constructs combined with vascularized tissues which are lined with cell cultures. Staged reconstructions using prelaminated epithelium, and prefabricated flaps, help in reconstruction of this complex structure. Prefabricating the flap at a different site allows for integration of the tissues prior to its transfer.

Method This article reports two patients planned for tracheal reconstruction for the purpose of advanced papillary carcinoma of the thyroid invading the trachea. Staged reconstruction using a prefabricated radial artery forearm flap (RAFF) and split rib cartilage was performed. In the second patient, a young girl, a similar construct of the RAFF, prelaminated with buccal mucosa, was performed. However, in the latter case, an intraoperative decision by the head and neck team to limit excision of the trachea sparing the mucosa was taken; the reconstruct in the forearm was redundant and needed to be discarded, replacing the defect with a free superficial circumflex iliac artery perforator (SCIP) flap.

Result At 3 years follow-up, both the patients are free of disease, with the construct serving its purpose in the older female.
A practical tool for selecting microalgal species for biodiesel production
Authors: Martín L. A. , Popovich C. A. , Damiani M. C. , Leonardi P. I.
Published: December 2020

In the search for energy sources to replace fossil fuels, microalgae have shown promising characteristics. Their cultures have several advantages over the conventional crops used for commercial biodiesel: they have fast growth rates and a high lipid content and can grow in environments unfit for agriculture. However, relatively few species have so far been studied as biodiesel feedstock. In order to facilitate the search for potentially useful species/strains, in this work, a bioprospecting tool based on biomass and oil production process requirements, triacylglyceride content, and biodiesel properties has been developed. For this purpose, an overall score (OS) was proposed as a tool based on biological, economic, and environmental factors. By applying the OS to nine species, we were able to narrow down the number of species within the diatom group, which are potentially suitable for large-scale biodiesel production. Halamphora coffeaeformis, Navicula cincta, and N. gregaria were the species with the highest OS (1.65-1.5). It is expected that this tool will provide a useful contribution to the criteria applied in the selection of microalgal species for large-scale biodiesel production.
Modeling of resistive plasma response in toroidal geometry using an asymptotic matching approach
Authors: Wang Zhirui , Glasser Alan H. , Brennan Dylan , Liu Yueqiang , Park Jongkyu
Published: December 2020

The method of solving the linear resistive plasma response, based on the asymptotic matching approach, is developed for full toroidal tokamaks by upgrading the resistive DCON code [A. H. Glasser, Z. R. Wang, and J.-K. Park, Phys. Plasmas 23, 112506 (2016)]. The derived matching matrix, asymptotically matching the outer and inner regions, indicates that the applied three dimension (3-D) magnetic perturbations contribute additional small solutions at each resonant surface due to the toroidal coupling of poloidal modes. In contrast, the resonant harmonic only affects the corresponding resonant surface in the cylindrical plasma. The solution of the ideal outer region is critical to the asymptotic matching and is challenging in toroidal geometry due to the singular power series solution at the resonant surfaces. Thus, a systematic verification of the outer region Δ′ matrix is made by reproducing the well-known analytical Δ′ result in Furth et al. [Phys. Fluids 16, 1054–1063 (1073)] and by making a quantitative benchmark with the PEST3 code [A. Pletzer and R. L. Dewar, J. Plasma Phys. 45, 427–451 (1991)]. Finally, the reconstructed numerical solution of the resistive plasma response from the toroidal matching matrix is presented. Compared with the ideal plasma response, the global structure of the response can be affected by the small finite island at the resonant surfaces.
Lévy noise-driven escape from arctangent potential wells
Authors: Capała Karol , Padash Amin , Chechkin Aleksei V. , Shokri Babak , Metzler Ralf , Dybiec Bartłomiej
Published: December 2020

The escape from a potential well is an archetypal problem in the study of stochastic dynamical systems, representing real-world situations from chemical reactions to leaving an established home range in movement ecology. Concurrently, Lévy noise is a well-established approach to model systems characterized by statistical outliers and diverging higher order moments, ranging from gene expression control to the movement patterns of animals and humans. Here, we study the problem of Lévy noise-driven escape from an almost rectangular, arctangent potential well restricted by two absorbing boundaries, mostly under the action of the Cauchy noise. We unveil analogies of the observed transient dynamics to the general properties of stationary states of Lévy processes in single-well potentials. The first-escape dynamics is shown to exhibit exponential tails. We examine the dependence of the escape on the shape parameters, steepness, and height of the arctangent potential. Finally, we explore in detail the behavior of the probability densities of the first-escape time and the last-hitting point.
Heat transfer model based on diffusion layer theory for dropwise condensation with high non-condensable gas
Authors: Liu Weihong , Ling Xiang
Published: December 2020

A new heat-transfer model for dropwise condensation with non-condensable gas (NCG) is developed, which can be used in the design and calculations of a dehumidifier in humidification–dehumidification technology. A single-droplet heat-transfer model is established via the rounded analysis of all the contributing thermal resistances based on the diffusion-layer theory. Combined with the drop size distribution, the heat flux of dropwise condensation with NCG is determined, and the error between the predicted results and previous experimental data is found to be within ±20%. The effects of different parameters on the heat transfer of dropwise condensation with NCG are investigated, and the results indicate that there is an optimal contact angle to maximize the heat flux, which depends on the NCG content. The thickness of the coating layer has little effect on the heat flux at a given thermal conductivity of the coating layer, indicating that the dropwise condensation effect can be improved by increasing the thickness of the coating layer, neglecting the heat-transfer deterioration due to the additional thermal resistance during dropwise condensation with NCG.
Spectral Fresnel filter for pulsed broadband terahertz radiation
Authors: Liu Xinrui , Kulya Maksim S. , Petrov Nikolay V. , Grachev Yaroslav V. , Song Mingzhao , Tcypkin Anton N. , Kozlov Sergey A. , Zhang Xi-Cheng
Published: December 2020

We proposed a simple and cost-effective method to manipulate the temporal and spectral properties of pulsed terahertz waves. A deep modulation of a pulse spectrum was both numerically and experimentally verified using Fresnel apertures with a radius ranging from several to several tens of the central wavelength of the broadband terahertz radiation. N-fold frequency minima were formed in the spectrum at a specific axial position behind the filter. Non-paraxial properties of this filter were also analyzed. A significant value (35%) of the ratio of the longitudinal to the transverse field component at the filter frequency was obtained. The measured results agree well with the simulation and theoretical predictions. The property of such a diffractive Fresnel notch filter can benefit the generation of longitudinal terahertz fields and relevant applications.
Demonstration of bright x-ray sources from solid and foam TiO2 targets at the Shenguang-III prototype laser facility
Authors: Dong Yunsong , Tu Shaoyong , Sun Chuankui , Niu Gao , Che Xingsen , Wei Minxi , Li Yukun , Yin Chuansheng , Liu Xincheng , Yan Ji , Zhang Jiyan , Huang Tianxuan , Miao Wenyong , Yang Jiamin , Jiang Shaoen
Published: December 2020

Enhancement of x-ray sources from laser-produced plasmas is significant in wide-ranging applications. Solid and foam TiO2 targets were both used to generate bright x-ray sources at the Shenguang-III prototype laser facility, with a total laser power of 3.2 TW. The new foam targets were with an ultra-low initial density of 8.1 mg/cm3 and a high Ti fraction of 33 sat. %. By absolute measurements, the multi-keV x rays of the 4 keV–7 keV band and 1.6 keV–4.4 keV band and the total x rays above 0.1 keV of the foam target have simultaneously shown conversion enhancements of 1.4, 3.1, and 2.3 times, respectively, compared with the solid target. A much larger emission volume and an average electron temperature of 3.2 keV by moving the foci of laser beams inner were obtained for the foam target, providing a good condition for multi-keV x-ray production.
Sub-milliwatt optical frequency combs in dual-pumped high-Q multimode silicon resonators
Authors: Zhang Yaojing , Zhong Keyi , Hu Gaolei , Yi Dan , Kumar Rakesh Ranjan , Tsang Hon Ki
Published: December 2020

We experimentally study the generation of optical frequency combs (OFCs) in dual-pumped high-quality factor (>106) multimode silicon racetrack resonators and show that sub-milliwatt (0.3 mW) input pump powers were sufficient to produce six-order OFC generation with eleven peaks, even in waveguides with normal dispersion. The low pump power and enhanced efficiency of the OFC generation can be attributed to mode coupling between two mode families of the multimode resonator, which acts to change the effective magnitude and the sign of the local dispersion of the resonator. We experimentally observed that the OFC generation had 3.6 times more peaks and 12.1 dB higher conversion efficiency than that without any bias. We compared the efficiencies of the OFC generation at different pump wavelengths within and beyond the mode coupling region. At low pump powers circulating in the resonator, pump wavelengths in the mode coupling regime produced 1.3 times more peaks and 8 dB enhancement in conversion efficiency than pumping beyond the mode coupling regime. The experimental results were consistent with the theoretical simulations by solving the modified Lugiato–Lefever equation.
An ultrahigh vacuum-compatible reaction cell for model catalysis under atmospheric pressure flow conditions
Authors: Haunold Thomas , Rameshan Christoph , Bukhtiyarov Andrey V. , Rupprechter Günther
Published: December 2020

Atmospheric pressure reactions on model catalysts are typically performed in so-called high-pressure cells, with product analysis performed by gas chromatography (GC) or mass spectrometry (MS). However, in most cases, these cells have a large volume (liters) so that the reactions on catalysts with only cm2 surface area can be carried out only in the (recirculated) batch mode to accumulate sufficient product amounts. Herein, we describe a novel small-volume (milliliters) catalytic reactor that enables kinetic studies under atmospheric pressure flow conditions. The cell is located inside an ultrahigh vacuum chamber that is deliberately limited to basic functions. Model catalyst samples are mounted inside the reactor cell, which is locked to an oven for external heating and closed by using an extendable/retractable gas dosing tube. Reactant and product analyses are performed by both micro-GC and MS. The functionality of the new design is demonstrated by catalytic ethylene (C2H4) hydrogenation on polycrystalline Pt and Pd foils.
Lattice Boltzmann simulation of low-Reynolds-number cavitating contracting-nozzle flow interacting with a moving valve
Authors: Luo Tianpei , Xia Jun
Published: December 2020

Investigating internal-injector cavitating flow dynamics is difficult but important. The interaction of nozzle cavitation with the moving needle valve dictates the fuel mass flow rate and therefore spray combustion performance and emissions. In the present study, a two-dimensional low-Reynolds-number cavitating contracting-nozzle flow interacting with a moving valve is simulated using the lattice Boltzmann (LB) method. The Bhatnagar–Gross–Krook algorithm coupled with the immersed boundary method and an improved pseudo-potential multiphase flow model are employed and further developed based on the open-source LB code PALABOS. The performance of the immersed boundary method is first verified in a case where an oscillating cylinder moves according to a sine function in water. In order to improve the pseudo-potential model on its limitation of the density ratio, so to be used in engineering multiphase flow, the Carnahan–Starling equation of state is incorporated together with the exact difference method force scheme and an upgraded interaction force term. The upgraded pseudo-potential model proves via validations to be effective in improving numerical stability at large density ratios. With a seamless cooperation of the improved Shan–Chen model and the immersed boundary method achieved in PALABOS, cavitation in a contracting nozzle is simulated for a whole cycle of the valve motion. Cavitation dynamics under different fuel mass flow rates is investigated. It is found that cavitation dynamics, including interface conditions, cavitation bubble distributions, and inside-bubble vapor-phase flow fields, is distinctly different when the flow path is widely open and completely shut by the valve.
Conversion efficiency of resonant cavity enhanced narrow bandgap interband cascade photovoltaic cells
Authors: Huang Wenxiang , Yang Rui Q.
Published: December 2020

By combining an interband cascade (IC) configuration with an optical cavity, a novel approach to achieve efficient narrow bandgap photovoltaic (PV) cells is proposed. The proposed resonant cavity enhanced (RCE) ICPV cells can significantly alleviate the challenging issues in narrow bandgap semiconductor materials, which include a small absorption coefficient, a short diffusion length, and a high dark current density. Through simulations with realistic material parameters based on InAs/GaSb superlattice heterostructures, RCE ICPV cells are capable of achieving a conversion efficiency that exceeds 60%, which is much higher than what can be achieved with any other approach, especially with materials of a bandgap smaller than 0.3 eV. By varying structure parameters such as the absorber thickness, number of cascade stages, and the top mirror reflectance, we demonstrate how an RCE ICPV cell can be constructed to achieve an optimized device performance with high conversion efficiency. Also, a design example of a practical RCE narrow bandgap ICPV cell is provided.
Reaction front propagation in nanocrystalline Ni/Al composites: A molecular dynamics study
Authors: Politano O. , Baras F.
Published: December 2020

This work focuses on a class of nano-laminated Ni/Al composites fabricated by a rolling-stacking procedure. This method results in nano-laminated composites with a complex structure. Their reactivity was compared with that of reactive multilayer nanofoils with constant bilayer thickness. Typical samples are composed of randomly distributed grains of Ni and Al. The self-propagating reactive front presents peculiarities that are directly related to the initial microstructure. The combustion mode is unsteady, with shifts in velocity. The temperature profile is characterized by broad combustion and post-combustion zones. The instantaneous shape of the front is tortuous, with the appearance of hot spots correlated with the underlying grain configuration. Local dynamics was studied in order to detect all the elemental processes occurring at nanoscale that trigger propagation: melting of Al, coarsening of Al grains, progressive exothermic dissolution mixing, heterogeneous nucleation, and growth of the intermetallic phase, B2-NiAl. The role of the complex initial microstructure was clearly demonstrated.
Temperature dependence of Ga2O3 growth by halide vapor phase epitaxy on sapphire and
β
-Ga2O3 substrates
Authors: Goto Ken , Nakahata Hidetoshi , Murakami Hisashi , Kumagai Yoshinao
Published: December 2020

The influence of growth temperature on Ga2O3 growth by atmospheric-pressure halide vapor phase epitaxy was investigated on sapphire and β-Ga2O3 substrates. In the growth-temperature range of 700–1000 °C, the growth rate of Ga2O3 was in agreement with that estimated by thermodynamic analysis under the assumption of growth under thermal equilibrium. However, when the growth temperature was lower than 700 °C, the growth rate, which decreased as the growth temperature decreased, deviated from that estimated by thermodynamic analysis, reflecting growth behavior under nonthermal equilibrium. X-ray diffraction and optical absorption measurements of the grown layers revealed that the Ga2O3 growth under nonthermal equilibrium was constrained by the crystal structure of the substrate, i.e., the metastable phase α-Ga2O3(0001) grew on the sapphire (0001) substrate, whereas the stable phase β-Ga2O3 grew homoepitaxially on a β-Ga2O3(001) substrate. However, under thermal equilibrium, the growth of the stable phase β-Ga2O3 occurred irrespective of the substrate and the constraint from the crystal structure of the substrate was no longer observed. We also observed that in the β-Ga2O3 homoepitaxial layer grown under nonthermal equilibrium, crystal twinning occurred in the homoepitaxial layer, presumably due to an insufficient growth temperature.
Nobel Prize in Physics honors the discovery of a supermassive compact object at the heart of the Milky Way
Authors: Berkowitz Rachel
Published: December 2020

By tracking the orbits of stars close to the galactic center, Reinhard Genzel and Andrea Ghez ruled out all possibilities besides a black hole.
Charpentier, Doudna win chemistry Nobel for development of CRISPR-Cas genome editing
Authors: Miller Johanna L.
Published: December 2020

Although less than a decade old, the technology is already shaking up research in cell biology and molecular biophysics.
Statistical characteristics of laser interference and its effect on IR optoelectronic observation systems
Authors: Pavlov N.I. , Rezunkov Yu.A.
Published: December 2020

We consider statistical characteristics of laser interference recorded in the focal region of an IR optoelectronic observation system under field and out-of-field illumination by laser radiation. The applicability of the analytical description of experimental histograms of the laser interference signal distribution at the photodetector array output using the probability density approximations in the form of gamma distribution and the Gaussian function is substantiated. It is shown that the specific form of these functions is determined both by the mean value (mathematical expectation) of the interference signal and by the characteristic parameter M, which depends on the statistical properties of the laser interference.
Pump depletion in Raman lasing in a graded index multimode fibre
Authors: Kuznetsov A.G. , Kablukov S.I. , Podivilov E.V. , Babin S.A.
Published: December 2020

We examine multimode diode laser pump depletion in a graded index multimode (MM) fibre Raman laser generating a high-quality Stokes beam. Spatial ‘hole burning’ in the transmitted pump beam is demonstrated. A balance model is constructed for interaction of the pump and Stokes waves in the MM Raman laser. Analytical formulas are derived and used in calculations demonstrating qualitative agreement with experimental data. The origin of the observed quantitative discrepancies is discussed.
John Gooden and the Birmingham proton synchrotron
Authors: Gooden Brett A.
Published: December 2020

During World War 2, Sir Mark Oliphant began to plan for the construction of the world’s first proton synchrotron at the University of Birmingham. In March 1945, he offered a research fellowship to an enthusiastic and highly commended young physicist, John Stanley Gooden. Gooden had graduated from the University of Adelaide in 1941, and been working at the Radiophysics Laboratory, Sydney on radar research. With his wife, he arrived in Birmingham at the end of 1945, and immediately began work on the mathematical theory, design and construction of the proton accelerator. His enthusiasm and work ethic were infectious, and he soon became the project leader. In the latter part of 1947, Oliphant arranged for Gooden and John Fremlin to visit nuclear research facilities in the United States of America (USA) to gain knowledge about American plans for proton accelerators. They spent most of their time at the Radiation Laboratory, University of California, Berkeley and at Brookhaven National Laboratory, New York. The United Kingdom (UK) was exhausted after the war, and despite the best efforts of Gooden and Oliphant’s team, the construction of the synchrotron was slow. In 1947, Oliphant accepted a position as head of the Research School of Physical Sciences at the new Australian National University in Canberra. Gooden was the first staff appointment to the school. Oliphant planned to build a cyclosynchrotron at the university with Gooden as team leader. Tragically, in 1950, Gooden’s chronic nephritis deteriorated, and he died on 9 June 1950. Described by Oliphant as ‘my most brilliant student’, Gooden pioneered the theoretical basis and construction of the proton synchrotron. The Birmingham machine was finally completed in 1953, a year after the Brookhaven Cosmotron.
Valuation of peers’ safe choices is associated with substance-naïveté in adolescents
Authors: Chung Dongil , Orloff Mark A. , Lauharatanahirun Nina , Chiu Pearl H. , King-Casas Brooks
Published: December 2020

Significance

During adolescence, substance use and other health-risk behaviors emerge, particularly among those who associate with peers engaging in such behaviors and less so for adolescents with less deviant peers. Here, we provide behavioral and neural evidence for a beneficial role of safer peers, rather than a detrimental influence of risky peers, in guiding adolescents’ choices and substance use. The extent to which adolescents value peers’ safe choices predicted substance-naïveté even after controlling for other factors associated with substance use, while valuation of peers’ risky choices was unrelated to substance use. Whereas previous studies have largely examined associations between negative peers and increased health-risk behaviors, our data support a significant role of positive social peers for favorably influencing health-risk behaviors.
Periodic training of creeping solids
Authors: Hexner Daniel , Liu Andrea J. , Nagel Sidney R.
Published: December 2020

Significance

It is well appreciated that many disordered materials deform their shape irreversibly (plastically) under an external load (e.g., memory foam). Here, we show that this plasticity can be exploited to train materials to develop novel elastic responses by straining them periodically. By applying different periodic strains to a common viscoelastic material, we are able to design a number of different responses. These include a maximally negative Poisson’s ratio, bistable behavior, and nonlocal bond-specific responses. In contrast to computer-aided design, we rely on plasticity to self-organize the system in response to local stresses. This approach shows promise to achieve an unprecedented control over behavior at large strains well beyond the linear-response regime.
Fingerprint ridges allow primates to regulate grip
Authors: Yum Seoung-Mok , Baek In-Keun , Hong Dongpyo , Kim Juhan , Jung Kyunghoon , Kim Seontae , Eom Kihoon , Jang Jeongmin , Kim Seonmyeong , Sattorov Matlabjon , Lee Min-Geol , Kim Sungwan , Adams Michael J. , Park Gun-Sik
Published: December 2020

Significance

Why have primates evolved epidermal ridges on the volar regions of the hands and feet and with a much greater density of sweat glands than flat skin, which respond to anxiety rather than act as a thermoregulation mechanism? During contact with solid objects, the ridges are important for grip and precision manipulation by regulating moisture levels from either external sources or the sweat pores so that the friction is maximized and catastrophic slip is inhibited. An understanding of the underlying mechanisms involved has become particularly important with the almost ubiquitous contact of the finger pads with flat screens and recent developments in haptic feedback using ultrasonic vibrations for which the performance is critically related to the friction.
Mitochondrial Nuclear Retrograde Regulator 1 (MNRR1) rescues the cellular phenotype of MELAS by inducing homeostatic mechanisms
Authors: Aras Siddhesh , Purandare Neeraja , Gladyck Stephanie , Somayajulu-Nitu Mallika , Zhang Kezhong , Wallace Douglas C. , Grossman Lawrence I.
Published: December 2020

Significance

Pathogenic mtDNA tRNA mutations, such as the 3243A>G MELAS mutation, generally result in multisystem failure. In cybrids harboring ∼70% 3243G mutant mtDNA, the mitochondrial unfolded protein response (UPR
mt
) is impaired. Mitochondrial Nuclear Retrograde Regulator 1 (MNRR1, or CHCHD2) is a bi-organellar (mitochondrial and nuclear) protein that is reduced in ∼70% 3243G cybrid cells. Under stress conditions, MNRR1 import into mitochondria is impaired, resulting in its preferential concentration in the nucleus. Increased nuclear MNRR1 induces the UPR
mt
through regulation of the ATF5 transcription factor. Overexpression of MNRR1 in ∼70% 3243G cybrid cells induces the UPR
mt
, autophagy, and mitochondrial biogenesis and restores mitochondrial respiratory function; furthermore, the proportion of wild-type mtDNA increases. Thus, MNRR1 overexpression might be beneficial for mtDNA diseases.
Fuel and oxygen harvesting from Martian regolithic brine
Authors: Gayen Pralay , Sankarasubramanian Shrihari , Ramani Vijay K.
Published: December 2020

Significance

The active Martian water cycle, i.e., the presence of a shallow water table and soluble perchlorates in the Martian regolith, enables the concurrent production of hydrogen fuel and life-support oxygen on Mars through perchlorate brine electrolysis. Our perchlorate brine electrolyzer operating under simulated Martian surface conditions produces >25× the amount of oxygen produced by the Mars Oxygen In-Situ Resource Utilization Experiment from NASA’s Mars 2020 mission for the same input power. This work provides an additional route to help NASA fulfill its mandate to land humans on Mars by 2033. Furthermore, our perchlorate brine electrolyzers are more efficient than state-of-the-art alkaline water electrolyzers under terrestrial conditions, providing a pathway to utilize suboptimal input feeds to produce ultrapure hydrogen and oxygen.
Fouling-resistant zwitterionic polymers for complete prevention of postoperative adhesion
Authors: Zhang Ershuai , Song Boyi , Shi Yuanjie , Zhu Hui , Han Xiangfei , Du Hong , Yang Chengbiao , Cao Zhiqiang
Published: December 2020

Significance

Postoperative peritoneal adhesions are frequent complications for almost any types of abdominal and pelvic surgery and lead to numerous medical problems. Current antiadhesion solutions include pharmacological treatment and physical barriers but are underperformed and can only alleviate or reduce adhesions to some extent. Here we show that a zwitterionic polymer solution after a convenient topical application onto the traumatized surface can reliably and completely prevent the postoperative adhesions, as demonstrated in three clinically relevant but increasingly challenging rat models. The overall success rate of complete prevention is above 93%—a major leap of antiadhesion performance.
Intergenerational transfer of DNA methylation marks in the honey bee
Authors: Yagound Boris , Remnant Emily J. , Buchmann Gabriele , Oldroyd Benjamin P.
Published: December 2020

Significance

Intergenerational epigenetic inheritance is usually considered to be of minor significance in mammals because the epigenome is reprogrammed twice between each generation. Yet whether this paradigm holds in nonmammalian organisms is largely unknown. Here, we show that epigenetic marks are transferred across generations in an invertebrate, the honey bee. We found that the epigenome is much more similar between fathers and daughters than between unrelated males and females of different generations within each colony. Epigenetic marks are not only conserved across generations, but also across somatic and germline tissues. Epigenetic reprogramming may thus be a mammalian-specific feature, suggesting a heightened capacity for epigenetic marks to influence evolutionary adaptation across the tree of life.
FGF23 contains two distinct high-affinity binding sites enabling bivalent interactions with α-Klotho
Authors: Suzuki Yoshihisa , Kuzina Ekaterina , An Seong J. , Tome Francisco , Mohanty Jyotidarsini , Li Wenxue , Lee Sangwon , Liu Yansheng , Lax Irit , Schlessinger Joseph
Published: December 2020

Significance

FGF23 is a circulating hormone produced in bone tissue that acts in the kidney to increase phosphate excretion and vitamin D metabolism essential for calcium absorption. Mutations that elevate FGF23 abundance cause autosomal dominant hypophosphatemic rickets or tumor-induced osteomalacia. Loss of FGF23, on the other hand, causes increased phosphate levels, such as in familiar tumor calcinosis. Here we show that the region in FGF23 responsible for KLA binding contains two distinct binding sites for KLA, demonstrating that FGF23 is able to simultaneously bind and assemble two KLA molecules. An engineered protein containing the identified KLA ligand acts as a potent FGF23 inhibitor offering new pharmacological intervention for treating diseases caused by excessive FGF23 abundance or activity.
A non-canonical Hedgehog pathway initiates ciliogenesis and autophagy
Authors: Akhshi Tara , Trimble William S.
Published: December 2020

Primary cilia function as critical signaling hubs whose absence leads to severe disorders collectively known as ciliopathies; our knowledge of ciliogenesis remains limited. We show that Smo induces ciliogenesis through two distinct yet essential noncanonical Hh pathways in several cell types, including neurons. Surprisingly, ligand activation of Smo induces autophagy via an LKB1-AMPK axis to remove the satellite pool of OFD1. This is required, but not sufficient, for ciliogenesis. Additionally, Smo activates the Gαi-LGN-NuMA-dynein axis, causing accumulation of a portion of OFD1 at centrioles in early ciliogenesis. Both pathways are critical for redistribution of BBS4 from satellites to centrioles, which is also mediated by OFD1 centriolar translocation. Notably, different Smo agonists, which activate Smo distinctly, activate one or the other of these pathways; only in combination they recapitulate the activity of Hh ligand. These studies provide new insight into physiological stimuli (Hh) that activate autophagy and promote ciliogenesis and introduce a novel role for the Gαi-LGN-NuMA-dynein complex in this process.
Nucleonic localisation and alpha radioactivity
Authors: Ebran J-P , Khan E , Lasseri R-D
Published: December 2020

Relativistic energy density functional approaches are known to well describe nuclear states which involve alpha clusters. Here, alpha emitting nuclei are analyzed through the behavior of the spatial localisation of nucleonic states, calculated with an axially deformed relativistic Hartree–Bogoliubov approach over the nuclear chart. The systematic occurrence of more localised valence states, having an n = 1 radial quantum number, allows to pinpoint nuclei in agreement with experimentally known alpha-emitters. The cases of 212Po and 104Te are investigated, showing the concomitant contributions of the pseudospin symmetry and the presence of n = 1 states, on the alpha preformation probability. The impact of the localisation of valence states, on alpha preformation probability, is then analyzed. It allows to study shell effects on this probability, over isotopic and isotonic chains. Finally, a phenomenological law is also provided, relating this probability to the radial quantum number of the valence states.
Setting Scottish diagnostic reference levels for mammography incorporating both craniocaudal and oblique projections between 30 and 80 mm
Authors: Weir A , Schofield K A , McCurrach A
Published: December 2020

Optimisation must be carried out on all medical radiological units to ensure doses are as low as reasonably practicable, consistent with the intended purpose. To achieve this, population doses must be estimated and diagnostic reference levels (DRLs) set. For mammography examinations, mean glandular doses (MGDs) are calculated for this purpose. The average MGD per unit is compared to the national mammography DRL, which is applicable to compressed breast thicknesses (CBTs) of 50–60 mm for oblique (OB) views only and set using data from screening units. It is the purpose of this work to assess planar MGDs across Scotland and set DRLs based on data collected from all screening and symptomatic units across Scotland, considering craniocaudal (CC) and OB views and a wider range of CBTs. Data from the most recent dose audit (spanning 2015–2017) for 67 mammography x-ray units were collated and analysed (26 195 images). No large differences between MGD of CC and OB views were found when considering specific CBT ranges (median difference 2.6%). There was, however, a significant difference between screening and symptomatic data (19%). As expected, MGD increased with CBT and there were significant differences in MGD between manufacturers. From the data analysed, Scottish DRLs were set based on 95th percentile values for digital mammography units for three CBT ranges (30–49, 50–60 and 61–80 mm): 1.3, 1.8 and 2.6 mGy respectively. These values consider OB and CC views collectively. Fifth percentile values are quoted to highlight units at greater risk of insufficient image quality. These MGD values, together with image quality assessments, will facilitate optimisation across Scotland. Results show that use of different CBT ranges and inclusion of CC views increases the number of images included in dose audit data analysis from approximately 12%–92%, which is substantially more representative of the population.
Development of nano-immunosensor with magnetic separation and electrical detection of Escherichia coli using antibody conjugated Fe3O4@Ppy
Authors: Srinivasan Sumithra Y , Gajbhiye Virendra , Bodas Dhananjay
Published: December 2020

Detection of bacterial pathogens is the need of the hour due to the increase in antibiotic resistance and the infusion of multi-drug-resistant parasites. The conventional strategies such as ELISA, PCR, and MNP based tests for the detection are efficient but they are cost, time, lab, and manpower intensive. Thus, warranting a simple and effective technique for rapid detection of bacterial pathogens. Magnetic nanoparticles (NPs) have proved to be better alternatives for separation of bacterial pathogens from a variety of sample sources. However, the use of magnetic NPs has not been successful in the detection of these parasites. The current work involves the coating of magnetic NPs (Fe3O4) with a conducting polymer (polypyrrole; Ppy) to facilitate simultaneous separation and detection. Electrical (conductivity) measurement was the mode of choice due to the sensitivity, accuracy, and ease it offers. To enhance the conductivity, carboxylic groups were expressed on the Fe3O4@Ppy complex and to ensure specificity, E. coli specific antibodies were conjugated. The resulting complex at various process parameters was characterized using FTIR, VSM, and SEM. SEM images were recorded to ensure bacterial separation at optimal process parameters. The impedance analysis and conductivity measurements were carried out for the sample volume of 15 μl. The bacterial suspension from 101–106 CFU ml−1 was successfully detected with a limit of detection of 10 CFU ml−1 within 10 min using a simplistic detection method.