bluuebunny/crossref_metadata_2025 huggingface dataset:
The influence of temperature and TMGa flow rate on the quality of p-GaN
Authors: Cao Zikun , Wang Xiaowei , Zhao Degang , Liang Feng , Liu Zongshun
Published: March 2021

This paper studies in detail the influence of growth temperature and the TMGa flow rate on the quality of p-GaN. Through Hall and atomic force microscope tests on six samples of two growth series, we can find that a higher growth temperature and lower TMGa flow rate can enhance the electrical properties and improve the surface morphology of the material, that is, lower resistivity, greater carrier concentration, higher mobility, and lower roughness. These two growth methods share similar processes to improve material properties. The enhancement of gallium atom migration is the reason for the improvement in surface morphology. The reduction in carbon impurities is key to improving electrical device performance through secondary ion mass spectroscopy and room temperature photoluminescence tests. Moreover, the severity of contamination on the sample surface is positively correlated with the roughness of the sample, which further illustrates the importance of better surface quality.
Fractional operators for the magnetic dynamic behavior of ferromagnetic specimens: An overview
Authors: Ducharne B. , Tsafack P. , Deffo Y. A. Tene , Zhang B. , Sebald G.
Published: March 2021

This paper reviews the use of the fractional derivative operators for the dynamic magnetization of ferromagnetic specimens. Magnetic behaviors in ferromagnetic specimens are strongly nonlinear and frequency dependent. Magnetism has an atomic origin but the magnetic behavior as observed at the human scale is highly affected by phenomena occurring at larger scales. Under the influence of an external magnetic field, the homogeneity of a ferromagnetic sample magnetization is linked to the excitation dynamics. Models and simulations in this domain are strongly needed, as they provide theoretical explanations and allow us to anticipate complex phenomena, difficult to observe in a practical way. On the one hand, such multi-scale dynamical behaviors can hardly be taken into account with the usual mathematical operators. On the other hand, correct simulation results on large frequency bandwidths can be obtained using fractional derivative operators. The use of fractional derivatives can be envisaged through different approaches: Lump models based on time fractional differential equations is one option, and fractional anomalous diffusion equations is another. In this manuscript, these two methods are detailed and compared. Theoretical results are compared to experimental ones, and conclusions and perspectives are drawn such as possible improvements.
Observation of a superparamagnetic breakdown in gadolinium chloride filled double-walled carbon nanotubes
Authors: Ncube S. , Coleman C. , Flahaut E. , Bhattacharyya S. , Prinsloo A. R. E. , Sheppard C. J.
Published: March 2021

In this article, the magnetic properties of gadolinium chloride-filled double-walled carbon nanotubes (GdCl3@DWNTs) in the temperature range 2-300 K are explored. The temperature-dependent phonon frequencies of the G-band were studied from 80-300 K to investigate the effect of temperature on the magnetic ordering. Temperature-dependent susceptibility measurements show that the GdCl3@DWNTs sample has a pronounced superparamagnetic phase from 83 K. The temperature dependence of the G-band frequency for filled tubes exhibited a distinct difference compared to pristine nanotubes, where a sharp phonon hardening at low temperatures was observed. A correlation between the onset temperature of superparamagnetism and the abrupt G-band phonon hardening in the filled tubes was verified. GdCl3@DWNTs were characterized by a finite remnant magnetization at 300 K which decreased as the temperature was lowered because of the presence of the discontinuous magnetic nanoparticles, providing a superparamagnetic contribution characterized by an S-shaped non-saturating hysteresis loop at 2 K. Remarkably, the onset of superparamagnetism, marked by the bifurcation point, occurred at roughly the same temperature where the G-band phonon frequency showed a pronounced hardening at approximately 80 K, indicating a close correlation between phonon modes and spin clusters.
Penetrating the Mind
Authors: Marro Joaquin , Torres Joaquin J.
Published: March 2021

Scientists continue to delve on sure grounds into the secrets of the mind and, finishing this essay, we return to consider a few significant novel observations. These advances steered us to assemble and refine the image we have been sketching, then confirmed how the result is a perfectly consistent and useful theoretical framework, from which the latest experiments certainly suggest new paths. Furthermore, this chapter plays the role of an epilogue, finally emphasizing how the facts strongly endorse that, like systems in a traditional physics laboratory, the brain displays phases conforming to mental states; it moves—naturally and irregularly—through and between them, and it continually looks for criticality.
Concordance line sorting in The Prime Machine
Authors: Jeaco Stephen
Published: March 2021

Corpus data provide evidence of the patterning of language, and one way word usage can be analysed is through the
study of concordance lines. While popular concordancers provide different sorting methods, they are typically only able to display
lines in the order in which they occur in the corpus, randomly, or alphabetically by words in slots to the left or right of the
word of interest. Less sophisticated users may find recognising patterns from these orderings quite challenging. This paper
considers possible needs of language learners in terms of concordance ranking and introduces two methods which have been adopted
and developed for The Prime Machine. The first method uses repeated patterns, measuring the number of matches
made with other lines in the set. The second method incorporates collocation scores, providing examples with strong collocations
from the entire corpus at the top of sampled concordance lines.
Type V myosin focuses the polarisome and shapes the tip of yeast cells
Authors: Dünkler Alexander , Leda Marcin , Kromer Jan-Michael , Neller Joachim , Gronemeyer Thomas , Goryachev Andrew B. , Johnsson Nils
Published: March 2021

The polarisome is a cortical proteinaceous microcompartment that organizes the growth of actin filaments and the fusion of secretory vesicles in yeasts and filamentous fungi. Polarisomes are compact, spotlike structures at the growing tips of their respective cells. The molecular forces that control the form and size of this microcompartment are not known. Here we identify a complex between the polarisome subunit Pea2 and the type V Myosin Myo2 that anchors Myo2 at the cortex of yeast cells. We discovered a point mutation in the cargo-binding domain of Myo2 that impairs the interaction with Pea2 and consequently the formation and focused localization of the polarisome. Cells carrying this mutation grow round instead of elongated buds. Further experiments and biophysical modeling suggest that the interactions between polarisome-bound Myo2 motors and dynamic actin filaments spatially focus the polarisome and sustain its compact shape.
Spritz: general relativistic magnetohydrodynamics with neutrinos
Authors: Cipolletta F , Kalinani J V , Giangrandi E , Giacomazzo B , Ciolfi R , Sala L , Giudici B
Published: March 2021

We here present a new version of the publicly available general relativistic magnetohydrodynamic (GRMHD) code Spritz, which now includes an approximate neutrino leakage scheme able to handle neutrino cooling and heating. The leakage scheme is based on the publicly available ZelmaniLeak code, with a few modifications in order to properly work with Spritz. We discuss the involved equations, physical assumptions, and implemented numerical methods, along with a large battery of general relativistic tests performed with and without magnetic fields. Our tests demonstrate the correct implementation of the neutrino leakage scheme, paving the way for further improvements of our neutrino treatment and the first application to magnetized binary neutron star mergers. We also discuss the implementation in the Spritz code of high-order methods for a more accurate evolution of hydrodynamical quantities.
Electrostatic doping of graphene from a LiNbO3 (0001) substrate
Authors: Yue Chen , Lu Xiaomei , Zhang Junting , Huang Fengzhen , Zhu Jinsong
Published: March 2021

To investigate the special electrical phenomena in a graphene/ferroelectric field-effect transistor, we perform density-functional first-principles calculations on a graphene/LiNbO3 (0001) hybrid structure, and then study the effects of a Au counter electrode and water adsorption. Graphene is p-type and n-type doped by a LiNbO3 positive and negative surface, respectively, and the conductivity increases while the Dirac cone persists. The Au counter electrode introduces an additional charge injection relative to the surface polarity and weakens the electrostatic doping effect. With the help of the electrons from the Au counter electrode, water adsorption could switch the conductive type of graphene. We also find an interesting phenomenon whereby the coupling of graphene with a negative surface is significantly stronger than that with a positive surface, possibly related to the different polar terminals (LiO3/Nb).
Mechanistic study of catalytic CO2 hydrogenation in a plasma by operando DRIFT spectroscopy
Authors: Parastaev A , Kosinov N , Hensen E J M
Published: March 2021

Plasma-enhanced heterogeneous catalysis offers a promising alternative to thermal catalysis for many industrially relevant processes. There is only limited mechanistic understanding about the relation between the interactions of highly energetic electrons and excited molecules with heterogeneous catalysts in a plasma and their catalytic performance. Herein, a novel operando infrared spectroscopy cell is presented allowing the investigation of surface intermediates upon exposure of a catalyst to plasma. The polyether ether ketone cell enclosure embedding a quartz reactor is operated at atmospheric pressure and can be heated to 250 °C. A case study involved the characterization of surface intermediates during CO2 hydrogenation on a Co/CeZrO4 catalyst. The temperature was monitored using online UV–Vis spectroscopy. This combined approach offers new experimental insights into plasma-catalyst synergy. The most important one is the demonstration of CO2 methanation at the catalyst surface at room temperature in a plasma.
Three-dimensional composite electrospun nanofibrous membrane by multi-jet electrospinning with sheath gas for high-efficiency antibiosis air filtration
Authors: Jiang Jiaxin , Shao Zungui , Wang Xiang , Zhu Ping , Deng Shiqing , Li Wenwang , Zheng Gaofeng
Published: March 2021

Three-dimensional (3D) composite polyvinylidene fluoride (PVDF)/polyacrylonitrile (PAN) electrospun nanofibrous membranes combining both thick and thin nanofibers have been fabricated by the method of multi-jet electrospinning with sheath gas to realize high-efficiency air filtration under a low pressure drop. The thin PAN nanofibers form a dense membrane, with a strong capturing ability on the ultra-fine particles, while the thick PVDF nanofibers play a 3D supporting effect on the thin PAN nanofibers. In this case, the combination results in a fluffy membrane with higher porosity, which could achieve the airflow passing through the membrane without the air pressure drop. The effects of the composite manner of thick nanofibers and thin nanofibers are investigated, in order to optimize the air filtration performance of the 3D composite nanofibrous membrane. As a result, the maximum quality factor for air filtration could reach up to 0.398 Pa−1. The particle-fiber interaction model was used to simulate the air filtration process as well, and the simulation results were fairly consistent with the experimental results, providing a guidance method for the optimization of composite nanofibrous membrane for high-efficiency air filtration. More interestingly, a cationic poly[2-(N,N-dimethyl amino) ethyl methacrylate] (PDMAEMA) was added in the PVDF solution to obtain a composite air filtration membrane with excellent antibiosis performance, which achieved the highest inhibition rate of approximately 90%. In short, this work provides an effective way to promote antibiosis air filtration performance by using an electrospun nanofibrous membrane, and might also effectively accelerate the biological protection application of current air filtration membranes.
Metallo-deuteroporphyrins derived multi-layered hollow carbon spheres electrocatalysts for highly efficient oxygen reduction reaction
Authors: Zhang Han , Wang Yue , Liu Shaojun , Li Chenglong , Li Lixiang , An Baigang , Sun Chengguo
Published: March 2021

The development of low-cost, highly efficient and stable non-precious metal electrocatalyst for the oxygen reduction reaction (ORR) substituting Pt has attracted much attention. Herein, we developed a promising structural platform for the fabrication of carbon nanospheres functionalized with hollow nanostructures of M-NHCS (M = Fe, Co and Mn) based on metallo-deuteroporphyrins (MDP). Benefited from the multi-layered active sites and hollow substrate with more exposed active surface area, convenient channels for the transport of electrons, the resulting Fe-NHCS electrocatalysts exhibit enhanced electrocatalytic performance in ORR with an onset potential of 0.90 V (versus RHE), and a high selectivity in the direct 4-electron pathway. The Fe-NHCS electrocatalysts also show a good methanol tolerance superior to Pt/C catalysts and an extremely high stability with only 13.0 mV negative after 5000 cycles in alkaline media. Experiments have verified that maintaining the multi-layered Fe−N−C active sites and hollow substrate were essential to deliver the high performance for ORR. The work opens new avenues for utilizing MDP-based materials in future energy conversion applications.
A robotically assisted 3D printed quality assurance lung phantom for Calypso
Authors: Capaldi Dante P I , Skinner Lawrie B , Dubrowski Piotr , Zhang Hao , Xing Lei , Chuang Cynthia F , Loo Billy W , Bush Karl K , Fahimian Benjamin P , Yu Amy S
Published: March 2021

Purpose. Radiation dose delivered to targets located near the upper-abdomen or in the thorax are significantly affected by respiratory-motion. Relatively large-margins are commonly added to compensate for this motion, limiting radiation-dose-escalation. Internal-surrogates of target motion, such as a radiofrequency (RF) tracking system, i.e. Calypso® System, are used to overcome this challenge and improve normal-tissue sparing. RF tracking systems consist of implanting transponders in the vicinity of the tumor to be tracked using radiofrequency-waves. Unfortunately, although the manufacture provides a universal quality-assurance (QA) phantom, QA-phantoms specifically for lung-applications are limited, warranting the development of alternative solutions to fulfil the tests mandated by AAPM’s TG142. Accordingly, our objective was to design and develop a motion-phantom to evaluate Calypso for lung-applications that allows the Calypso® Beacons to move in different directions to better simulate true lung-motion. Methods and Materials. A Calypso lung QA-phantom was designed, and 3D-printed. The design consists of three independent arms where the transponders were attached. A pinpoint-chamber with a buildup-cap was also incorporated. A 4-axis robotic arm was programmed to drive the motion-phantom to mimic breathing. After acquiring a four-dimensional-computed-tomography (4DCT) scan of the motion-phantom, treatment-plans were generated and delivered on a Varian TrueBeam® with Calypso capabilities. Stationary and gated-treatment plans were generated and delivered to determine the dosimetric difference between gated and non-gated treatments. Portal cine-images were acquired to determine the temporal-accuracy of delivery by calculating the difference between the observed versus expected transponders locations with the known speed of the transponders’ motion. Results. Dosimetric accuracy is better than the TG142 tolerance of 2%. Temporal accuracy is greater than, TG142 tolerance of 100 ms for beam-on, but less than 100 ms for beam-hold. Conclusions. The robotic QA-phantom designed and developed in this study provides an independent phantom for performing Calypso lung-QA for commissioning and acceptance testing of Calypso for lung treatments.
The effect of Ag doping and point defects on the electronic structure and photocatalytic properties of ZnO using first-principles
Authors: Liu Yajing , Hou Qingyu
Published: March 2021

At present, the photocatalytic properties of Ag-doped ZnO have been extensively studied, but the mechanism of Ag-doped ZnO photocatalysis is not fully understood. The effect of intrinsic point defects on the performance and mechanism of Ag-doped ZnO photocatalysis has rarely been studied by theoretical calculations. To solve such problems, first-principle calculations were performed to systematically investigate the effect of Ag doping (AgZn/Agi) and point vacancy (VZn/VO) on the photocatalytic performance and mechanism of ZnO. It was found that the ZnO:Agi+VZn showed the strongest structural stability compared to the three doping methods, ZnO:AgZn+VZn, ZnO:AgZn+VO, and ZnO:Agi+VO. In addition, the doping of interstitial Ag with Zn vacancy shrank the ZnO bandgap to the smallest bandgap width (2.46 eV), thereby broadening the ZnO absorption spectrum into the visible range. The study of the dipole moment, static dielectric constant, and carrier effective mass showed that the ZnO:Agi+VZn exhibited excellent photocatalytic polarization and activity in the visible range. In particular, along the [001] direction, electrons and holes showed stronger mobility, resulting in effective separation and transfer of electron-hole pairs and a reduction in the electron-hole complex rate. The results provided a theoretical reference for in-depth understanding and designing of novel ZnO photocatalysts.
Physical and mechanical properties of ternary Ge-Se-Sb glasses for near-infrared applications
Authors: El-Denglawey A , Dahshan A , Aly K A , Saddeek Y B
Published: March 2021

Many physical properties such as the average coordination number (CN), the compactness (δ), the overall bond energy (〈E〉), the cohesive energy (CE), the mean bond energy (E
s), and the overall electronegativity difference (Δχ) as well as the degrees of ionicity (Ion) and covalency (Cov) were estimated theoretically. The chemical bond approach (CBA) was used to predict the type and proportion of the formed bonds in the studied glasses. Consequently, several structural and physical properties have been estimated. The results show that the studied glasses are rigidly connected, having an average coordination number increase from 2.41 to 2.61. Two approaches have been successfully used to estimate the band gap (E
g) theoretically compared with the previously published experimental values for the Ge18Se82−xSbx (5 ≤ x ≤ 25 at. %) glasses. Values of E
g decrease from 1.59 to 1.15 eV by an increase of the Sb content from 5 to 25 at. %. i.e. the wavelengths corresponding to E
g values lie in the near-infrared range of spectra, which make these glasses candidates for the near-infrared applications. Furthermore, the ultrasonic longitudinal (v

L
) and shear wave (v

T
) velocities propagating through the glasses have been used to estimate the mechanical parameters such as the elastic bulk modulus, Poisson’s ratio, Young’s modulus, micro-hardness, and temperature of Debye. It was found that a change in slope occurs for various physical, mechanical, and structural properties near the stoichiometric composition (x ≈ 18 at. %) at which the glass structure consists of heteropolar bonds only.
Validity of thermodynamic laws and weak cosmic censorship for AdS black holes and black holes in a cavity *
Authors: Wang Peng , Wu Houwen , Ying Shuxuan
Published: March 2021

By throwing a test charged particle into a Reissner-Nordstrom (RN) black hole, we test the validity of the first and second laws of thermodynamics and the weak cosmic censorship conjecture (WCCC) with two types of boundary conditions: the asymptotically anti-de Sitter (AdS) space and a Dirichlet cavity wall placed in an asymptotically flat space. For the RN-AdS black hole, the second law of thermodynamics is satisfied, and the WCCC is violated for both extremal and near-extremal black holes. For the RN black hole in a cavity, the entropy can either increase or decrease depending on the change in the charge, and the WCCC is satisfied/violated for the extremal/near-extremal black hole. Our results indicate that there may be a connection between the black hole thermodynamics and the boundary condition imposed on the black hole.
Effect of skull thickness and conductivity on current propagation for noninvasively injected currents
Authors: Forssell Mats , Goswami Chaitanya , Krishnan Ashwati , Chamanzar Maysamreza , Grover Pulkit
Published: March 2021

Objective. When currents are injected into the scalp, e.g. during transcranial current stimulation, the resulting currents generated in the brain are substantially affected by the changes in conductivity and geometry of intermediate tissue. In this work, we introduce the concept of ‘skull-transparent’ currents, for which the changing conductivity does not significantly alter the field while propagating through the head. Approach. We establish transfer functions relating scalp currents to head potentials in accepted simplified models of the head, and find approximations for which skull-transparency holds. The current fields resulting from specified current patterns are calculated in multiple head models, including MRI heads and compared with homogeneous heads to characterize the transparency. Experimental validation is performed by measuring the current field in head phantoms. Main results. The main theoretical result is derived from observing that at high spatial frequencies, in the transfer function relating currents injected into the scalp to potential generated inside the head, the conductivity terms form a multiplicative factor and do not otherwise influence the transfer function. This observation is utilized to design injected current waveforms that maintain nearly identical focusing patterns independently of the changes in skull conductivity and thickness for a wide range of conductivity and thickness values in an idealized spherical head model as well as in a realistic MRI-based head model. Experimental measurements of the current field in an agar-based head phantom confirm the transparency of these patterns. Significance. Our results suggest the possibility that well-chosen patterns of current injection result in precise focusing inside the brain even without a priori knowledge of exact conductivities of intermediate layers.
Two-dimensional resistive MHD simulation of the optimized plasma formation in the spherical tokamaks
Authors: Ahmadi T. , Tanabe H. , Ono Y.
Published: March 2021

We present 2D global MHD simulation results of the optimized start-up scenarios for the spherical tokamak to maximize the ion heating energy determined by the value of the poloidal private flux during the merging start-ups. The series of simulations has successfully revealed the dependence of the poloidal private flux on the in-vessel poloidal coils’ separation length under the fixed amount of coils’ magnetic energy. The radial and azimuthal locations of the internal coils need to be optimized to maximize high private flux and consequently high ion heating energy. In the case of a two poloidal field (PF) coils system, the private flux and ion heating energy increase with the coils’ separation length. Installing two additional PF coils improves the private flux significantly, even if the coils’ separation length is short.
Retraction: Detailed kinetic modeling of nitroglycerin low-temperature decomposition (J. Phys.: Conf. Ser.
1721 012002)
Authors: Glorian J , Baschung B
Published: March 2021

This article is retracted at the request of the authors, who withdrew from this conference before the event and as such, should not have been included in the proceedings. The conference organisers apologise to the authors and IOP Publishing for this error. IOP Publishing have investigated according to COPE guidelines and agree the article should be retracted.

Retraction published: 03 March 20201
Capability of active thermography to detect and localize pores in Metal Additive Manufacturing materials
Authors: D’Accardi Ester , Ulbricht Alexander , Krankenhagen Rainer , Palumbo Davide , Galietti Umberto
Published: March 2021

Active thermography is a fast, contactless and non-destructive technique that can be used to detect internal defects in different types of material. Volumetric irregularities such as the presence of pores in materials produced by the Additive Manufacturing processes can strongly affect the thermophysical and the mechanical properties of the final component. In this work, an experimental investigation aimed at detecting different pores in a sample made of stainless AISI 316L produced by Laser Powder Bed Fusion (L-PBF) was carried out using pulsed thermography in reflection mode. The capability of the technique and the adopted setups in terms of geometrical and thermal resolution, acquisition frequency and energy density of the heating source were assessed to discern two contiguous pores as well as to detect a single pore. Moreover, a quantitative indication about the minimum resolvable pore size among the available and analysed defects was provided. A powerful tool to assess the limits and the opportunities of the pulsed technique in terms of detectability and localizability was provided by comparing active thermography results to Computed Tomography as well as a related Finite Element Analysis (FEA) to simulate the pulsed heating transfer with Comsol.
Ultrasonic and thermographic fatigue monitoring on a full-scale CFRP aeronautical component after repairing
Authors: Dattoma V , Nobile R , Palano F , Panella F W , Pirinu A , Saponaro A
Published: March 2021

The identification of defects in real components made in composite material assumes considerable importance in the aeronautical field, as irregularities in the material can compromise its functionality. Also, the possibility (NDT) to verify the effectiveness of repairing on the component during exercise through non-destructive testing techniques has great importance.

The goal of the present study is the application of the ultrasound and thermographic techniques for the identification of defects in a repaired component and the evaluation of the damage caused by the application of cyclical fatigue loads. All the important factors were studied, improving ultrasound scanning and allowing evaluating the effectiveness of the techniques used. In this paper, one case of study was proposed for non-destructive damage evaluation employing Phased Array ultrasonic and thermographic methods on aeronautical CFRP component. The structural element analysed is a spar with a double-T section with a hole and presents a repair by scarfing and hot bond process. The experimental results obtained shown the validity of the ultrasonic and thermographic technique for the sensitivity in detecting defects on full-scale aeronautical components with short execution and scan times.
An experimental-numerical methodology for the nondestructive assessment of the dynamic elastic properties of adhesives
Authors: Tridello A , Ciardiello R , Paolino DS , Goglio L
Published: March 2021

In the last years, lightweight design has become a priority in many industrial sectors, like as the aerospace and the automotive industry, mainly due to the strict regulations in terms of gas emission and pollution. Together with lightweight materials, the use of adhesives to join different parts permits to significantly reduce the weight of mechanical assemblies. For a proper design of the joints, the mechanical properties of adhesives should be correctly experimentally assessed. However, the experimental assessment of the adhesive mechanical properties can be complex, since they can be hardly estimated from traditional experimental tests on lap-joint or butt-joint specimens. The development of an experimental procedure for the assessment of the adhesive properties is therefore of interest. In the present paper, a methodology for the assessment of the dynamic elastic properties of adhesives, i.e., Young’s modulus and the loss factor, is proposed. The procedure is based on the Impulse Excitation Technique and Finite Element Analyses (FEA). An automated routine has been written to assess the elastic properties by minimizing the difference between the frequency response obtained experimentally and through FEA. The proposed methodology has been experimentally validated to estimate the mechanical properties of an epoxy adhesive for automotive applications.
Influence of SLM parameters on the compressive behaviour of lattice structures in 17-4PH stainless steel
Authors: Bertocco A , Esposito L , Aurino A , Borrelli D , Caraviello A
Published: March 2021

Additive manufacture (AM) technologies allow innovative structural design, including complex lattice structures. Selective laser melting (SLM) is an AM process that enables the manufacture of space filling lattice structures. Lattice structures are topologically ordered, three-dimensional open-celled structures composed of one or more repeating unit cells. From a mechanical designer viewpoint, a great advantage offered by cellular materials is high strength accompanied by a relatively low mass. Due to their complex structure, fine geometry and the absence of supports structures, the setting of the best parameters to print lattice structures is difficult and could negative influence their mechanical response. This study investigated how different parameters settings influence the compression behaviour of lattice structures in stainless steel 17-4PH (AISI-630) printed by SLM. A comparison between compressive response of structures printed with different parameters is presented and considerations about their behaviour exposed.
Laser shock composite microforming of Fe-based amorphous alloys
Authors: Gu Xin , Wang Xiao , Cui Jiankun , Ma Youjuan , Zhang Haokun , Wang Keyang , Lu Jiaxin
Published: March 2021

To address the shortcomings of Fe-based amorphous alloys that are difficult to plastically form at room temperature, this study used high strain rate laser instead of traditional loading methods to conduct composite microforming of drawing, punching, and blanking. This article mainly explored the influence of laser energy and soft film thickness on the forming accuracy and depth, morphological characteristics, thickness distribution and mechanical properties. Result showed that the forming accuracy increased with the increase in the laser energy. However, the forming depth decreased when the laser energy was large. The forming accuracy was good when the soft film thickness was small. Abundant shear bands were distributed on the surface, indicating that the plastic deformation was realized on the basis of the generation and propagation of the shear bands. The cross-sectional morphology was also composed of smooth and choroid regions, and their composition ratio also varied in different regions. The bottom region had the smallest thickness, and the flange region had the largest thickness. The distribution of the nanohardness on cross-section was roughly the same as that of the workpiece thickness. The nanohardness was small when the thickness was thin. The elastic modulus gradually decreased from the flange region to the bottom region.
Preparation of black phosphorus coatings with photo-thermal conversion properties
Authors: Liu Hehuan , Shi Yunbo , Tang Bolun , Wang Tian , Zhang Huanhuan
Published: March 2021

Black phosphorus (BP) is a semiconductor material with excellent optical properties. To explore a more convenient method for preparation bulk BP and facilitate new applications of BP in engineering field, we used a single-zone tube furnace to fabricate bulk BP using tin and iodine as mineralisers. Further, a BP slurry with a uniform particle size was prepared by cutting the bulk BP in a solvent. BP coatings with different thicknesses were prepared, and their photo-thermal conversion properties were evaluated. The characterisation and test results showed that the BP coating was superimposed by BP flakes with an estimated plane size of ∼10 μm. The infrared absorptivity of the BP coatings was 87.83%–92.48%. The results clearly indicated that the BP coatings exhibit photo-thermal conversion properties that can be exploited for various applications.
Efficient dye discoloration of modified Lamiaceae leaves
Authors: Aljohani Meshari M H , Almizraq Jassim M J , Albalawi Abdulrahman M , Alshammari Almathna S A , Albalawi Nader O S , Albalawi Abdulrahman N S A , Alatwi Qasem A Q , Keshk Ali A , Althaqafy Adel D , Al-Aoh Hatem A
Published: March 2021

The powder of Lamiaceae Leaves was modified by Zinc Chloride (ZnCl2). The Chemical Modified Lamiaceae Leaves Powder (CMLLP) was characterized by BET surface analyzer, FTIR, SEM and Theydan and Ahmed method. It was found that this adsorbent has pHZPC of 6.2, surface area of 104.78 m2g−1, pore volume of 0.00464 cc/g and average pore diameter of 2647.813 Å. This sorbent was used as a cheap adsorbent for the extraction of Methylene Blue (MB) from contaminated solutions. The effect of temperature, pH of solution, time of contact and MB primary concentration were also investigated. All of these variables have positive impacts on this adsorption. The data obtained from the isotherm’s experiments, were analysed using three models. The obtained results confirmed that model of Langmuir was the most efficient. The capacities of this adsorption were found to be 333.33, 384.62, 434.78 and 476.19 mg g−1 at 25, 35, 45 and 60 °C, correspondingly. Three models of kinetic were applied to determine the constants of this adsorption kinetics. It was observed that the kinetic results follow the 2nd order more than the other two kinetic models. Moreover, thermodynamic constants were determined, which showed that this adsorption is an exothermic and spontaneous process.
Heavy elements cause hefty debate
Authors: Cooper Keith
Published: March 2021

Were heavy elements produced by colliding neutron stars or supernovae? Keith Cooper tunes in to a new dispute
Madness in the method
Authors: Crease Robert P
Published: March 2021

A new book suggests that traditional notions about “the scientific method” are flawed and misleading, as Robert P Crease discovers
Ask me anything: Carol Marsh
Authors: Commissariat Tushna
Published: March 2021

Carol Marsh is deputy head of electronics engineering at aerospace engineering company Leonardo and is based at its site in Edinburgh, UK.
Emerging inorganic solar cell efficiency tables (version 2)
Authors: Zakutayev Andriy , Major Jonathan D , Hao Xiaojing , Walsh Aron , Tang Jiang , Todorov Teodor K , Wong Lydia H , Saucedo Edgardo
Published: March 2021

This paper presents the second version of the efficiency tables of materials considered as emerging inorganic absorbers for photovoltaic solar cell technologies. The materials collected in these tables are selected based on their progress in recent years, and their demonstrated potential as future photovoltaic absorbers. The first part of the paper consists of the guidelines for the inclusion of the different technologies in this paper, the verification means used by the authors, and recommendation for measurement best practices. The second part details the highest world-class certified solar cell efficiencies, and the highest non-certified cases (some independently confirmed). The third part highlights the new entries including the record efficiencies, as well as new materials included in this version of the tables. The final part is dedicated to review a specific aspect of materials research that the authors consider of high relevance for the scientific community. In this version of the efficiency tables, we are including an overview of the latest progress in quasi one-dimensional absorbers, such as antimony chalcogenides, for photovoltaic applications.
The Arakelov-Zhang pairing and Julia sets
Authors: Bridy Andrew , Larson Matt
Published: March 2021

The Arakelov-Zhang pairing

⟨
ψ
,
ϕ
⟩

\langle \psi ,\phi \rangle

is a measure of the “dynamical distance” between two rational maps

ψ
\psi

and

ϕ
\phi

defined over a number field

K
K

. It is defined in terms of local integrals on Berkovich space at each completion of

K
K

. We obtain a simple expression for the important case of the pairing with a power map, written in terms of integrals over Julia sets. Under certain disjointness conditions on Julia sets, our expression simplifies to a single canonical height term; in general, this term is a lower bound. As applications of our method, we give bounds on the difference between the canonical height

h
ϕ

h_\phi

and the standard Weil height

h
h

, and we prove a rigidity statement about polynomials that satisfy a strong form of good reduction.
Relative and Absolute Risk to Guide the Management of Pulse Pressure, an Age-Related Cardiovascular Risk Factor
Authors: Melgarejo Jesus D , Thijs Lutgarde , Wei Dong-Mei , Bursztyn Michael , Yang Wen-Yi , Li Yan , Asayama Kei , Hansen Tine W , Kikuya Masahiro , Ohkubo Takayoshi , Dolan Eamon , Stolarz-Skrzypek Katarzyna , Cheng Yi-Bang , Tikhonoff Valérie , Malyutina Sofia , Casiglia Edoardo , Lind Lars , Sandoya Edgardo , Filipovský Jan , Narkiewicz Krzysztof , Gilis-Malinowska Natasza , Kawecka-Jaszcz Kalina , Boggia José , Wang Ji-Guang , Imai Yutaka , Verhamme Peter , Trenson Sander , Janssens Stefan , O’Brien Eoin , Maestre Gladys E , Gavish Benjamin , Staessen Jan A , Zhang Zhen-Yu
Published: March 2021

Background

Pulse pressure (PP) reflects the age-related stiffening of the central arteries, but no study addressed the management of the PP-related risk over the human lifespan.

Methods

In 4,663 young (18–49 years) and 7,185 older adults (≥50 years), brachial PP was recorded over 24 hours. Total mortality and all major cardiovascular events (MACEs) combined were coprimary endpoints. Cardiovascular death, coronary events, and stroke were secondary endpoints.

Results

In young adults (median follow-up, 14.1 years; mean PP, 45.1 mm Hg), greater PP was not associated with absolute risk; the endpoint rates were ≤2.01 per 1,000 person-years. The adjusted hazard ratios expressed per 10-mm Hg PP increments were less than unity (P ≤ 0.027) for MACE (0.67; 95% confidence interval [CI], 0.47–0.96) and cardiovascular death (0.33; 95% CI, 0.11–0.75). In older adults (median follow-up, 13.1 years; mean PP, 52.7 mm Hg), the endpoint rates, expressing absolute risk, ranged from 22.5 to 45.4 per 1,000 person-years and the adjusted hazard ratios, reflecting relative risk, from 1.09 to 1.54 (P < 0.0001). The PP-related relative risks of death, MACE, and stroke decreased >3-fold from age 55 to 75 years, whereas absolute risk rose by a factor 3.

Conclusions

From 50 years onwards, the PP-related relative risk decreases, whereas absolute risk increases. From a lifecourse perspective, young adulthood provides a window of opportunity to manage risk factors and prevent target organ damage as forerunner of premature death and MACE. In older adults, treatment should address absolute risk, thereby extending life in years and quality.
Are Some COVID-19 Vaccines Better Than Others? Interpreting and Comparing Estimates of Efficacy in Vaccine Trials
Authors: Rapaka Rekha R , Hammershaimb Elizabeth A , Neuzil Kathleen M
Published: March 2021

Coronavirus disease 2019 (COVID-19) vaccine trials provide valuable insight into the safety and efficacy of vaccines, with individually randomized, placebo-controlled trials being the gold standard in trial design. However, a myriad of variables must be considered as clinical trial data are interpreted and used to guide policy decisions. These variables include factors such as the characteristics of the study population and circulating severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) strains, the force of infection, the definition and ascertainment of endpoints, the timing of vaccine efficacy assessment, and the potential for performance bias. In this Viewpoints article, we discuss critical variables to consider when comparing efficacy measurements across current and future COVID-19 vaccine trials.
Networks with growth and preferential attachment: modelling and applications
Authors: Piva Gabriel G , Ribeiro Fabiano L , Mata Angélica S
Published: March 2021

This article presents a brief overview of the main network models that use growth and preferential attachment. We start with the classical model proposed by Barabási and Albert: nodes are added to the network connecting preferably to nodes that are more connected. We also present models that consider more representative elements from social perspectives, such as the homophily between the nodes and the fitness that each node has, to build connections. Furthermore, we show a version of these models that includes Euclidean distance between the nodes as a preferential attachment component. Our objective is to study the fundamental properties of these networks, as distribution of connectivity, degree correlation, shortest path, cluster coefficient and how these characteristics are affected by the preferential attachment rules. In addition to the review, we also provided an application of these models using real-world networks.
An immunologically friendly classification of non-peptidic ligands
Authors: Edwards Lindy , Jackson Rebecca , Overton James A , Vita Randi , Blazeska Nina , Peters Bjoern , Sette Alessandro
Published: March 2021

The Immune Epitope Database (IEDB) freely provides experimental data regarding immune epitopes to the scientific public. The main users of the IEDB are immunologists who can easily use our web interface to search for peptidic epitopes via their simple single-letter codes. For example, ‘A’ stands for ‘alanine’. Similarly, users can easily navigate the IEDB’s simplified NCBI taxonomy hierarchy to locate proteins from specific organisms. However, some epitopes are non-peptidic, such as carbohydrates, lipids, chemicals and drugs, and it is more challenging to consistently name them and search upon, making access to their data more problematic for immunologists. Therefore, we set out to improve access to non-peptidic epitope data in the IEDB through the simplification of the non-peptidic hierarchy used in our search interfaces. Here, we present these efforts and their outcomes.

Database URL:  http://www.iedb.org/
Novel device-based therapies to improve outcome in ST-segment elevation myocardial infarction
Authors: De Maria Giovanni Luigi , Garcia-Garcia Hector M , Scarsini Roberto , Finn Aloke , Sato Yu , Virmani Renu , Bhindi Ravinay , Ciofani Jonathan L , Nuche Jorge , Ribeiro Henrique B , Mathias Wilson , Yerasi Charan , Fischell Tim A , Otterspoor Luuk , Ribichini Flavio , Ibañez Borja , Pijls Nico H J , Schwartz Robert S , Kapur Navin K , Stone Gregg W , Banning Adrian P
Published: March 2021

Primary percutaneous coronary intervention (PPCI) has dramatically changed the outcome of patients with ST-elevation myocardial infarction (STEMI). However, despite improvements in interventional technology, registry data show little recent change in the prognosis of patients who survive STEMI, with a significant incidence of cardiogenic shock, heart failure, and cardiac death. Despite a technically successful PPCI procedure, a variable proportion of patients experience suboptimal myocardial reperfusion. Large infarct size and coronary microvascular injury, as the consequence of ischaemia–reperfusion injury and distal embolization of atherothrombotic debris, account for suboptimal long-term prognosis of STEMI patients. In order to address this unmet therapeutic need, a broad-range of device-based treatments has been developed. These device-based therapies can be categorized according to the pathophysiological pathways they target: (i) techniques to prevent distal atherothrombotic embolization, (ii) techniques to prevent or mitigate ischaemia/reperfusion injury, and (iii) techniques to enhance coronary microvascular function/integrity. This review is an overview of these novel technologies with a focus on their pathophysiological background, procedural details, available evidence, and with a critical perspective about their potential future implementation in the clinical care of STEMI patients.
Likelihood of injury due to vasovagal syncope: a systematic review and meta-analysis
Authors: Jorge Juliana G , Raj Satish R , Teixeira Pedro S , Teixeira Jose A.C , Sheldon Robert S
Published: March 2021

Aims

Vasovagal syncope (VVS) is the most common type of syncope and is usually considered a benign disorder. The potential for injury is worrisome but the likelihood is unknown. We aimed to determine the proportion of patients injured due to VVS.

Methods and results

A systematic search of studies published until August 2020 was performed in multiple medical and nursing databases. Included studies had data on the proportion of patients with injury due to VVS prior to study enrolment. Random effects methods were used. Twenty-three studies having 3593 patients met inclusion criteria. Patients were diagnosed clinically with VVS, and 82% had >2 syncopal episodes before enrolment. Tilt test was positive in 60% and 14 studies reported comorbidities (32.6% hypertensive). The weighted mean injury rate was 33.5% [95% confidence interval (CI): 27.3–40.5%]. The likelihood of injury correlated with population age (r = 0.4, P = 0.05), but not with sex, positive tilt test, or hypertension. The injury rates were 25.7% (95% CI: 19.1–32.8%) in studies with younger patients (mean age ≤50 years, n = 1803) and 43.4% (95% CI: 34.9–52.3%) in studies with older patients (P = 0.002). Nine studies reported major injuries; with a weighted mean rate of major injuries of 13.9% (95% CI: 9.5–19.8%).

Conclusion 

Injuries due to syncope are frequent, occurring in 33% of patients with VVS. The risk of major injuries is substantial. Older patients are at higher risk. Clinicians should be aware of the risk of injuries when providing care and advice to patients with VVS.
Rapid deployment of an algorithm to triage dental emergencies during COVID-19 pandemic
Authors: Perelman Sharon C , Erde Steven , Torre Lynda , Ansari Tunaidi
Published: March 2021

COVID-19 quickly immobilized healthcare systems in the United States during the early stages of the outbreak. While much of the ensuing response focused on supporting the medical infrastructure, Columbia University College of Dental Medicine pursued a solution to triage and safely treat patients with dental emergencies amid the pandemic. Considering rapidly changing guidelines from governing bodies, dental infection control protocols, and our clinical faculty's expertise, we modeled, built, and implemented a screening algorithm, which provides decision support as well as insight into COVID-19 status and clinical comorbidities, within a newly integrated electronic health record (EHR). Once operationalized, we analyzed the data and outcomes of its utilization and found that it had effectively guided providers in triaging patient needs in a standardized methodology. This article describes the algorithm’s rapid development to assist faculty providers in identifying patients with the most urgent needs, thus prioritizing treatment of dental emergencies during the pandemic.