bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of oxygen concentration on streamer propagation and ozone production in a single-filament streamer discharge at atmospheric pressure
Authors: Komuro Atsushi , Yoshino Akihiro , Wei Zhenyu , Ono Ryo
Published: March 2023

Limited research has been conducted on the formation mechanism of chemically active species in streamer discharges with respect to the oxygen concentration, which is critical to various applications such as ozone generation, air purification, and plasma-assisted combustion, among others. Herein, the oxygen concentration in an N2/O2 gas atmosphere is varied from 1% to 99% under atmospheric pressure and room temperature to investigate changes in the characteristics of streamer discharge propagation and generation of chemically active species. As the oxygen concentration increases from 10% to 90%, the decay rate of the discharge current, propagation velocity of the primary streamer, and ozone production efficiency increase. These phenomena are qualitatively explained by the electron attachment reaction to oxygen molecules and changes in the electron energy distribution function caused by the change in the oxygen concentration. However, the amount of discharge emission from N2(C) cannot be explained by changes in the fraction of electron energy lost in excitation of N2(C) and its quantum yield, implying that changes in the production of N2(C) in the primary and secondary streamers must be considered in a spatiotemporal manner. This study demonstrates that the ozone and N2(C) production characteristics in streamer discharges vary nonlinearly with respect to the oxygen concentration.
Observation of photoinduced polarons in semimetal 1T-TiSe2
Authors: Huang Yin , Lv Senhao , Liu Heyuan , Cheng Qiuzhen , Biao Yi , Lu Hongliang , Lin Xiao , Wang Zhuan , Yang Haitao , Chen Hailong , Weng Yu-Xiang
Published: March 2023

In this work, ultrafast carrier dynamics of mechanically exfoliated 1T-TiSe2 flakes from the high-quality single crystals with self-intercalated Ti atoms are investigated by femtosecond transient absorption spectroscopy. The observed coherent acoustic and optical phonon oscillations after ultrafast photoexcitation reveal the strong electron–phonon coupling in 1T-TiSe2. The ultrafast carrier dynamics probed in both visible and mid-infrared regions indicate that some photogenerated carriers localize near the intercalated Ti atoms and form small polarons rapidly within several picoseconds after photoexcitation due to the strong and short-range electron–phonon coupling. The formation of polarons leads to a reduction of carrier mobility and a long-time relaxation process of photoexcited carriers for several nanoseconds. The formation and dissociation rates of the photoinduced polarons are dependent on both the pump fluence and the thickness of TiSe2 sample. This work offers new insights into the photogenerated carrier dynamics of 1T-TiSe2, and emphasizes the effects of intercalated atoms on the electron and lattice dynamics after photoexcitation.
Reduced graphene oxide/ionic liquid composites with tunable interlayer spacing for improved charge/discharge kinetics in supercapacitors
Authors: Korkut Ayse Saliha , Uralcan Betul
Published: March 2023

The large specific surface area and high conductivity of reduced graphene oxide (RGO) make it a promising material for supercapacitors. However, aggregation of graphene sheets into graphitic domains upon drying hampers supercapacitor performance by drastically impeding ion transport inside electrodes. Here, we present a facile approach to optimize charge storage performance in RGO-based supercapacitors by systematically tuning their micropore structure. To this end, we combine RGOs with room temperature ionic liquids during electrode processing to impede stacking of sheets into graphitic structures with small interlayer distance. In this process, RGO sheets function as the active electrode material while ionic liquid serves both as a charge carrier and a spacer to control interlayer spacing inside electrodes and form ion transport channels. We show that composite RGO/ionic liquid electrodes with larger interlayer spacing and more ordered structure exhibit improved capacitance and charging kinetics.
Enhanced thermal properties of epoxy composites by constructing thermal conduction networks with low content of three-dimensional graphene
Authors: Li Changzheng , Huang Minjin , Zhang Zhe , Qin Yaoyu , Liang Lizhe , Tian Zhi Qun , Ali Asad , Shen Pei Kang
Published: March 2023

Micro/nano electronic devices heat dissipation depends heavily on the thermal interface materials (TIMs). Despite notable progress, it is hard to efficaciously enhance the thermal properties of the hybrid TIMs with high-load additives due to an absence of effective heat transfer routes. Herein, the low content of three-dimensional (3D) graphene with interconnected networks is adopted as the additive to improve the thermal properties of epoxy composite TIMs. The thermal diffusivity and thermal conductivity of the as-prepared hybrids were dramatically improved by constructing thermal conduction networks after adding 3D graphene as fillers. The 3D graphene/epoxy hybrid’s optimal thermal characteristics were observed at 1.5 wt% of 3D graphene content, corresponding to a maximum enhancement of 683%. Besides, heat transfer experiments were further performed to determine the superb heat dissipation potential of the 3D graphene/epoxy hybrids. Moreover, the 3D graphene/epoxy composite TIM was also applied to high-power LED to improve heat dissipation. It effectively reduced the maximum temperature from 79.8 °C to 74.3 °C. These results are beneficial for the better cooling performance of electronic devices and provide useful guidelines for advancing the next-generation TIMs.
Preparation of an amphiphilic peptide (P13) with proton sponge effect and analysis of its antitumor activity
Authors: Wu Yujia , Jin Weihao , Wang Shanyi , Li Wanzhen , Tao Yugui , Wang Jun , Yang Kai , Zhang Weiwei , Gui Lin , Ge Fei
Published: March 2023

In order to prevent drugs from being captured and degraded by the acidic environment of organelles, such as lysosomes, after entering cells, this study designed and synthesized a novel carrier amphiphilic polypeptide (DGRHHHLLLAAAA), designated P13, for use as a tumor-targeting drug delivery vehicle. The P13 peptide was synthesized by the solid phase synthesis method, and its self-assembly behavior and drug-loading capacity in aqueous solution were studied and characterized in vitro. Doxorubicin (DOX) was loaded by dialysis method, and P13 and DOX were mixed at a mass ratio of 6:1 to form regular rounded globules. The acid–base buffering capacity of P13 was investigated determined by acid–base titration. The results revealed that P13 had excellent acid–base buffering capacity, a critical micelle concentration value of about 0.000 21 g l−1, and the particle size of P13-Dox nanospheres was 167 nm. The drug encapsulation efficiency and drug loading capacity of micelles were 20.40 ± 1.21% and 21.25 ± 2.79%, respectively. At the concentration of 50 μg ml−1 of P13-DOX , the inhibition rate was 73.35%. The results of the in vivo antitumor activity assay in mice showed that P13-DOX also exhibited excellent inhibitory effect on tumor growth, compared with the tumor weight of 1.1 g in the control group, the tumor weight in the P13-DOX-treated group was only 0.26 g. Additionally, the results of hematoxylin and eosin staining of the organs showed that P13-DOX had no damaging effect on normal tissues. The novel amphiphilic peptide P13 with proton sponge effect designed and prepared in this study is expected to be a promising tumor-targeting drug carrier with excellent application potential.
Modeling plasma-induced surface charge effects on CO2 activation by single atom catalysts supported on reducible and irreducible metal oxides
Authors: Doherty Francis , Goldsmith Bryan R
Published: March 2023

The accumulation of negative surface charge on catalytic surfaces in the presence of low-temperature plasma (LTP) could influence catalytic performance. However, it is difficult to disentangle the role of surface charging and other LTP catalytic effects in experiment. Herein, we use density functional theory (DFT) modeling to understand the effect of plasma-induced surface charging on CO2 activation by atomically dispersed single atom (SA) catalysts on both reducible and irreducible metal oxide supports. We model CO2 adsorption strength and CO2 dissociation barriers for Co1, Ni1, Cu1, Rh1, Pd1, and Ag1 SAs on both reducible and irreducible supports, namely, CeO2(100), TiO2(101), and γ-Al2O3(110), to elucidate trends. We find that accumulated surface charge on the SA increases the CO2 adsorption strength and decreases the CO2 dissociation barrier for all studied SA/support combinations. For both charged and uncharged (neutral) systems, SAs on the reducible CeO2(100) support generally adsorb CO2 more weakly compared to when on irreducible supports like γ-Al2O3(110). SAs on γ-Al2O3(110) typically have larger barriers for CO2 dissociation for both charged and uncharged systems compared to TiO2(101) and CeO2(100). The magnitude of surface charging effects on CO2 binding energies and dissociation barriers depends sensitively on both the SA and the support. In some cases, the CO2 activation trends qualitatively change between neutral and charged systems for a fixed SA across different supports. This DFT modeling study demonstrates that surface charging should be considered in strong electric fields because it can have a large effect on molecule adsorption and bond-breaking on catalytic surfaces.
Effect of nano-size on magnetostriction of BiFeO3 and exceptional magnetoelectric coupling properties of BiFeO3_P(VDF-TrFE) polymer composite films for magnetic field sensor application
Authors: Pradhan Sonali , Deshmukh Pratik , Kambale Rahul C , Darvade Tulshidas C , Satapathy S , Majumder Shovan K
Published: March 2023

The existence of magnetostriction in bulk BiFeO3 is still a matter of investigation and it is also an issue to investigate the magnetostriction effect in nano BiFeO3. Present work demonstrates the existence of magnetostrictive strain in superparamagnetic (SPM) BiFeO3 nanoparticles at room temperature and the magnetoelectric (ME) coupling properties in composite form with P(VDF-TrFE). Despite few reports on the magnetostriction effect in bulk BiFeO3 evidenced by the indirect method, the direct method (strain gauge) was employed in this work to examine the magnetostriction of SPM BiFeO3. In addition, a high ME coupling coefficient was observed by the lock-in technique for optimized BiFeO3_P(VDF-TrFE) nanocomposite film. These nanocomposite films also exhibit room-temperature multiferroic properties. These results provide aspects of material with immense potential for practical applications in spintronics and magneto-electronics applications. We report a ME sensor using SPM BiFeO3_P(VDF-TrFE) nanocomposite film for detection of ac magnetic field.
First-principles calculations of electron-phonon coupling in NaSnSb: buckling and pressurization
Authors: Mace (徐文轩) George
Published: March 2023

In this paper, the electron-phonon coupling (EPC) properties of topological material NaSnSb has been explored, whose low phonon branch dominates the EPC constant λ. NaSnSb can remain the strength of its EPC with a slight compression of the distance of the Na and Sb atoms along the z-axis (z
Na–Sb), while further compression or stretching would destroy the strength of its EPC. By pressing, in the pressure range of 2 GPa, the superconducting transition temperature (T
c) of NaSnSb behaves similar to that of FeSe in the same pressure range, with a local minimum at 1 GPa and a maximum at 1.5 GPa. Both compressing z
Na–Sb and pressure lead to phonon softening of NaSnSb. The phonon softening induced by compressing z
Na–Sb is three-dimensional, whereas the phonon softening induced by compression is two-dimensional.
Record field in a 10 mm-period bulk high-temperature superconducting undulator
Authors: Zhang Kai , Pirotta Andrew , Liang Xiaoyang , Hellmann Sebastian , Bartkowiak Marek , Schmidt Thomas , Dennis Anthony , Ainslie Mark , Durrell John , Calvi Marco
Published: March 2023

A 10 mm-period, high-temperature superconducting (HTS) undulator consisting of 20 staggered-array GdBa2Cu3O7−x
(GdBCO) bulk superconductors has been fabricated and tested successfully. Each GdBCO disk was machined into a half-moon shape with micro-meter accuracy and shrink-fitted into a slotted oxygen-free copper disk which provided pre-stress and effective conduction-cooling. The HTS undulator prototype, consisting of GdBCO disks, copper disks, and CoFe poles fitted in a long copper shell, was field-cooled magnetized in fields of up to 10 T at 10 K. An undulator field of 2.1 T in a 4 mm magnetic gap was obtained. This field is the largest reported yet for the same gap and period length and exceeds the target value of 2 T for the meter-long HTS undulator scheduled for the hard x-ray I-TOMCAT beamline in the Swiss Light Source 2.0. We have demonstrated that bulk superconductor based undulators can provide significantly improved performance over alternative technologies.
Performance enhancement of coated conductor magnet with double-layer metal insulation
Authors: Wang Ruichen , Zhou Pengbo , Li Songlin , Gong Tianyong , Zhao Yue , Huang Zhen , Wang Lei , Liu Boqiang , Li Jing , Ma Guangtong
Published: March 2023

A double-layer metal-insulation method using brass sheets as the double-layer insulators is proposed in this paper. It can enhance the contact resistivity while preserving greater thermal conductivity merit. The underlying mechanism of the contact resistivity enhancement is to increase the number of contact surfaces and to degrade the contact quality between the insulators. Then, we wound a single-layer brass-insulation coil and a double-layer brass-insulation coil to compare their contact resistivities, and confirmed the effectiveness of the double-layer metal-insulation method. Furthermore, since the capacity to withstand the overcurrent is weakened with the increasing contact resistance of the metal-insulation coil, we further investigated the influence of the contact surface resistivity distribution on the coil performance under different scenarios to optimize the double-layer metal-insulation coil for receiving superior thermal stability. The simulation results indicate that dominant second contact surface resistivity and minimal first and third contact resistivity is the optimal design for the double-layer metal-insulation coil to receive the best thermal stability, irrespective of the cooling environment, contact resistivity magnitude, operating current and coil dimension. In addition, with regard to the thermal performance differences caused by the contact surface resistivity distribution, we found that the increment of contact surface resistivity and the overcurrent enlarged the distinctions at different levels.
Mechanism of ion track formation in silicon by much lower energy deposition than the formation threshold
Authors: Amekura H , Narumi K , Chiba A , Hirano Y , Yamada K , Yamamoto S , Ishikawa N , Okubo N , Toulemonde M , Saitoh Y
Published: March 2023

Mechanism of the ion track formation in crystalline silicon (c-Si) is discussed, particularly under 1–9 MeV C60 ion irradiation. In this energy region, the track formation was not expected because the energy E was much lower than the threshold of E
th = 17 MeV determined by extrapolation from higher energy data in the past literature. The track formation is different between irradiations of C60 ions and of monoatomic ions: The tracks were observed under 3 MeV C60 ion irradiation but not under 200 MeV Xe ions, while both the irradiations have the same electronic stopping (S
e) of 14 keV nm−1 but much higher nuclear stopping (S
n) for the former ions. The involvement of S
n is suggested for the C60 ions. While the inelastic thermal spike (i-TS) calculations predict that the high energy monoatomic ion irradiation forms the tracks, the tracks have never been experimentally detected, suggesting quick annihilation of the tracks by highly enhanced recrystallization in c-Si. Exceptions are C60 ions of 1–9 MeV, where the track radii are well reproduced by the i-TS theory with assuming the melting transition. Collisional damage induced by the high S
n from C60 ions obstructs the recrystallization in c-Si. Then the tracks formed by the melting transition survive against the recrystallization. This is a new type of the synergy effect between S
e and S
n, different from the already-known mechanisms, i.e., the pre-damage effect and the unified thermal spike. While c-Si was believed as a radiation-hard material in the S
e regime with high S
e threshold, this study suggests that c-Si has a low S
e threshold but with efficient recrystallization.
The assessment of the atmospheric air breakdown voltage generated by the interaction between microwaves and metallic wires
Authors: Mogîldea George , Mogîldea Marian , Zgura Sorin I , Craciun Doina , Popa Cristina , Prepelita Petronela , Bazavan Marian C , Craciun Valentin
Published: March 2023

The aim of this research is to understand the plasma initiation process generated by metallic wires when interacting with high energy density microwaves. Lead (Pb) and molybdenum (Mo) wires of 0.5 mm diameter were investigated in this experiment. The tip of the metallic wire was placed into the nodal point of a waveguide cavity attached to a microwave generator, where it was exposed to the high energy density of the microwave field. Following the interaction between microwaves and the metallic wire, a plasma was initiated having as effect the wire vaporization. The experiments were conducted in atmospheric air at ∼1 bar pressure. From optical emission spectroscopy investigations it was observed that electronic excitation of the plasma has high values and it is in a local thermal equilibrium. The theoretical calculation of the voltages induced in the metallic wires when exposed to high energy density microwave field are similar to those measured in air breakdown experiments. The scanning electron microscopy analysis of the tips of the metallic wires showed that the field emission process is responsible for the ignition of the metallic wires and plasma generation.
An atomistic study on tensile behaviors of nanocrystalline copper
Authors: Zhang Yaoxuan , Li Lili , Xiong Liping , He Zhongyi , Zhang Renhui , Wan Diqing , Tian Chuang , He Jiehong
Published: March 2023

In the present work, tensile behaviors of nanocrystalline copper influenced by size evenness of nanograins, crystallographic orientation, grain sizes, temperature, and strain rates are investigated by using molecular dynamics simulations. Results show that Young’s modulus decreases with decreasing grain sizes when grain sizes are smaller than 9.8 nm, which agrees well with the inverse Hall-Petch relation. It is also demonstrated that both strength and modulus of nanocrystalline copper with random-sized grains are slightly higher than those with even-sized nanograins. With increasing temperatures, the modulus generally decreases, while the deteriorate slope of random-sized grains is slightly steeper than that of even-sized grains and the modulus of random-sized presents higher when temperature is below 900 K. This work sheds deep insights into tensile behaviors of nanocrystalline coppers at the nanoscale.
Structural, morphological, and non-linear optical properties of thermally evaporated neodymium doped zinc oxide thin films
Authors: Yadav Sunny , Barala Monika , Dhar Rakesh , Mohan Devendra
Published: March 2023

The thermal evaporation procedure has been used in the current work to synthesize various compositions of neodymium-doped zinc oxide thin films with varied thicknesses on glass substrates. The Films have a hexagonal wurtzite structure, according to x-ray Diffraction (XRD) study, and the structure has not changed after doping of Neodymium. Raman spectroscopy revealed peaks at 100.49, 331, 434,574, and 581 cm−1 that supported the ZnO phase, and the intensity of the peaks reduced as the number of dopants rose. FTIR analysis verified that Nd had completely dispersed in ZnO. The calculations of the bandgap (Eg) and absorption coefficient (α) are done using absorption spectra. The Z-Scan method has been employed to assess nonlinear optical characteristics for all Nd-doped ZnO thin films. The samples show the change from saturable absorption (SA) to reverse saturable absorption (RSA), the process of focusing to self-defocusing, and vice versa. This is due to the fact that the two-photon process is more potent than the one-photon process. The acquired value of the third-order optical non-linear susceptibility χ
(3) is of the order of 10−5 to 10 −6 (e.s.u.) that makes the samples suitable for use in various photonic applications like using as an optical limiter and/or optical switch due to higher values of optical non-linear parameters.
Quantifying continuity of characteristics of composite quantum systems
Authors: Shirokov M E
Published: March 2023

We describe the most general form of the Alicki–Fannes–Winter method for obtaining uniform continuity bounds for characteristics of composite quantum systems and consider several modifications of this method, which make it applicable to a wide class of characteristics in both finite-dimensional and infinite-dimensional cases. We present uniform continuity bounds for the most important characteristics of composite quantum systems. Along with the results obtained earlier by various authors, we describe a number of new results proved by the proposed methods. In particular, we obtain new continuity bounds for the quantum discord, one-way classical correlation and its regularization in finite-dimensional and infinite-dimensional bipartite quantum systems.
New measurement of 4He and proton decays from resonant states in 19Ne*
Authors: Ma 马 Kai 凯 , Ye 叶 Yan-Lin 沿林 , Lin 林 Cheng-Jian 承键 , Chen 陈 Jia-Hao 家豪 , Wang 王 Dong-Xi 东玺 , Han 韩 Jia-Xing 家兴 , Jia 贾 Hui-Ming 会明 , Yang 杨 Lei 磊 , Yang 阳 Li-Sheng 黎升 , Hu 胡 Zi-Yao 梓瑶 , Chen 陈 Ying 莹 , Pu 蒲 Wei-Liang 伟良 , Li 李 Gen 根 , Tan 谭 Zhi-Wei 智威 , Huang 黄 Da-Hu 大湖 , Luo 骆 Tian-Peng 天鹏 , Zhong 钟 Shan-Hao 善豪 , Lou 楼 Jian-Ling 建玲 , Yang 杨 Xiao-Fei 晓菲 , Li 李 Zhi-Huan 智焕 , Li 李 Qi-Te 奇特 , Xu 许 Jin-Yan 金艳 , Yang 杨 Zai-Hong 再宏 , Wei 魏 Kang 康
Published: March 2023

A

Li(

O,

Ne

)

H multi-nucleon transfer-reaction experiment was performed to populate the highly excited states in

Ne. The subsequent decay particles,

He or protons from the

Ne resonant states, were detected in coincidence with the recoil

H. The excitation-energy spectra of

Ne were reconstructed using the detected proton or

He and the deduced

F or

O data, respectively. A broad resonance at about 7.85 MeV (1/2

) was observed, with partial decay widths different from the previously reported values, which may have a significant impact on the destruction of

F in astrophysical processes. Several resonances up to very high excitation energies have been identified with a large α-clustering strength, which confirm the formation of the cluster structure with a one-hole configuration in light nuclei and encourage further systematic studies of the cluster structure in

Ne.
Stabilization of trapped electron mode through effective diffusion in electron temperature gradient turbulence
Authors: Watanabe T.-H. , Maeyama S. , Nakata M.
Published: March 2023

Multi-scale gyrokinetic theory and simulations of a toroidal magnetized plasma have revealed the existence of cross-scale interactions of the trapped electron mode (TEM) and the electron temperature gradient (ETG) turbulence. Reduction of the TEM instability growth rate in the ETG turbulence is clearly identified, and is well represented in the form of effective diffusion. A theoretical model based on the stochastic forcing by the ETG turbulence well describes the turbulent diffusion coefficient observed in multi-scale turbulence simulations.
Knee Flexion/Extension Angle Measurement for Gait Analysis Using Machine Learning Solution “MediaPipe Pose” and Its Comparison with Kinovea®
Authors: Gupta Amit , Shrestha Pratisthit Lal , Thapa Bhola , Silwal Raman , Shrestha Raju
Published: March 2023

Human Gait Analysis is crucial in diagnosis, monitoring, treatment, and rehabilitation. It requires the measurement of gait parameters like joint angles, angular motion, ground reaction force (GRF), momentum, step width, step length, velocity, etc. This study introduces a markerless, easy-to-use approach for measuring one of the gait parameters i.e., knee flexion/extension angle, and verifies it with an existing standard marker-based approach. Knee flexion/extension angle is calculated via Machine Learning (ML) pose estimation model “MediaPipe Pose” and Computer vision (CV) without the use of markers. For the verification of accuracy, the obtained values are compared with the data on each video frame obtained from Kinovea® which is a marker-based motion analysis software. A correlation of 0.941 was observed between the results from Kinovea® and MediaPipe Pose. Similarly, the mean absolute error of knee angles was 5.88 degrees. The research shows that knee flexion/extension angle can be accurately measured using ML solution for high-fidelity body pose tracking. Professionals involved in the field of biomechanics, sports medicine, physiotherapy as well as other medical fields can use this method as an alternative markerless approach for knee flexion/extension angle measurement for gait analysis.
Parametric Modelling and Optimization of Alkaline Electrolyzer for the Production of Green Hydrogen
Authors: Niroula S , Chaudhary C , Subedi A , Thapa B S
Published: March 2023

Electrolysis is the process of decomposition of the liquid, containing ions by passing electricity through it. This process is achieved by an electrolyzer. An alkaline water electrolyzer uses electrical energy to break the chemical bond between hydrogen and oxygen in an alkaline electrolytic medium. The performance of the electrolyzer depends upon various parameters like temperature, pressure, ohmic overpotential, activation overpotential, etc. In this study, various parameters that affect the performance of the electrolyzer are identified and integrated using fundamental thermodynamics and electrochemical equations. A mathematical model is created in MATLAB/SIMULINK to analyse the voltage vs current density plot of the electrolyzer. An attempt is made to optimize the performance of the electrolyzer through the variation of the parameters. It was observed that increasing the operating temperature and decreasing the operating pressure favours the electrolysis process. Also, 30 wt% of KOH solution as electrolyte exhibits the optimal cell voltage as compared to 20 and 40 wt% solutions.
Green finance: current status, development, and future course of actions in China
Authors: Feng Wenfang , Bilivogui Pierre , Wu Jichao , Mu Xiaoyang
Published: March 2023

This study explores China’s implementation of a green financial system to combat the urgent climate emergency and achieve sustainable development amid rapid industrial and urban development. The research examines the current state of green finance in China, including its development, challenges, and future directions. The study finds that China has made significant progress in establishing green finance, being a leader in green financial products like green bonds and credits. Moreover, as suggested by some literature, green finance products could lead to CO2 reductions. However, challenges still remain, such as promoting green insurance, establishing a unified green financial system, and addressing the lack of asymmetry in green financial information. This research provides an essential contribution to the growing body of knowledge on green finance, offering useful insights into China’s unique approach to sustainable development through green finance.
Balancing performance of active magnetic regenerators: a comprehensive experimental study of aspect ratio, particle size, and operating conditions
Authors: Czernuszewicz Agata , Griffith Lucas , Slaughter Julie , Pecharsky Vitalij
Published: March 2023

Effective and, at the same time, efficient active magnetic regenerator (AMR) performance requires balanced geometry and operating conditions. Here the influence of regenerator shape, magnetocaloric material size, operating frequency, and utilization on the performance of gadolinium packed-particle bed AMRs is demonstrated experimentally. Various metrics are applied to assess effectiveness and efficiency. Observed temperature spans and cooling powers across a wide range of operating conditions are used to evaluate system performance and estimate exergetic cooling power and exergetic power quotient. A new metric combining exergetic cooling power and pump power provides an estimate of the maximum achievable second law efficiency. Five regenerator geometries with equal volumes and the aspect ratio from 1.0 to 3.8, and four different ranges of Gd spherical particles between 182 and 354 µm, are investigated. Improvements in system performance are demonstrated by a boost in specific cooling power of gadolinium from 0.85 to 1.16 W g−1 and maximum temperature span from 8.9 to 15.1 K. The optimum exergetic cooling power is observed for 1.37 utilization and 3 Hz operating frequency, exergetic power quotient exhibits a maximum at the same utilization but at 2 Hz frequency, while the highest efficiency is recorded at 1 Hz and utilization of 0.5, demonstrating that multiple performance metrics must be balanced to achieve regenerator design meeting all performance targets.
Meta-silencer with designable timbre
Authors: Wang Nengyin , Zhou Chengcheng , Qiu Sheng , Huang Sibo , Jia Bin , Liu Shanshan , Cao Junmei , Zhou Zhiling , Ding Hua , Zhu Jie , Li Yong
Published: March 2023

Timbre, as one of the essential elements of sound, plays an important role in determining sound properties, whereas its manipulation has been remaining challenging for passive mechanical systems due to the intrinsic dispersion nature of resonances. Here, we present a meta-silencer supporting intensive mode density as well as highly tunable intrinsic loss and offering a fresh pathway for designable timbre in broadband. Strong global coupling is induced by intensive mode density and delicately modulated with the guidance of the theoretical model, which efficiently suppresses the resonance dispersion and provides desirable frequency-selective wave-manipulation capacity for timbre tuning. As proof-of-concept demonstrations for our design concepts, we propose three meta-silencers with the designing targets of high-efficiency broadband sound attenuation, efficiency-controlled sound attenuation and designable timbre, respectively. The proposed meta-silencers all operate in a broadband frequency range from 500 to 3200 Hz and feature deep-subwavelength sizes around 50 mm. Our work opens up a fundamental avenue to manipulate the timbre with passive resonances-controlled acoustic metamaterials and may inspire the development of novel multifunctional devices in noise-control engineering, impedance engineering, and architectural acoustics.
A review on modelling and numerical simulation of micro hot embossing process: fabrication, mold filling behavior, and demolding analysis
Authors: Datta Subir , Deshmukh Swarup S , Kar Tuhin , Goswami Arjyajyoti
Published: March 2023

Micro-hot embossing (micro-HE) of polymeric materials creates exact micro/nanoscale designs. Micro-HE processes include plate-to-plate (P2P), roll-to-roll (R2R), and roll-to-plate (R2P). Micro-HE is preferred for large-scale production of micro-patterns on polymer substrates. However, the lack of simulation models for optimization and component design prevents the broad use of this technology. As the size of the micro patterns decreases from micron to sub-micron, it improves performance features. Micro-HE cannot be analyzed using software tools like injection molding since there is no macroscopic equivalent. Commercial simulation software covers injection molding and associated processes. No commercial tool covers all micro-HE process steps, variations, and boundary conditions. According to the author, such review articles are not in the literature. This article summarizes the simulation work in the micro-HE process field related to replication accuracy, mold filling behaviour. In addition to this various models were discussed based on properties of material, based on various forces participate in the HE process, and gives a detailed idea about mold-filling behavior and demolding analysis. Finally, challenges and future scope related to modelling and simulation work in field of hot embossing has been presented.
Efficient resource utilization scheme for real-time IoT application for D2D communication: A distance and power-driven based approach
Authors: Pandey Krishna , Chandra Saurabh , Arya Rajeev
Published: March 2023

Device-to-Device (D2D) communication provides real-time functioning support for IoT applications using fifth-generation (5G) technologies. In an In-band underlay D2D model, resource allocation is a key issue. To overcome this issue, a distance and power-driven model is proposed. A mathematical problem is formulated with the main objective is to maximizing the spectral efficiency of the network. This work utilizes the concept of distributed processing for achieving our goal. First of all, we proposed a distance and power-driven based resource allocation mechanism (DPRAM) for the improvement in spectral efficiency by mitigating D2D and interference between the base station and D2D users. Then, the applicability of the proposed work has been checked by using the Sigmoidal and Logarithmic based utility functions for the delay tolerance device and real-time IoT application respectively. Simulation results show that the proposed work is capable of providing the best solution as compared to random allocation methods and pure ALOHA by 63.41% and 95.12% and 60% and 96% improvement in system capacity. Analysis of performance parameters such as sigmoidal and logarithmic utility function approves that our proposed approach may be suitable for delay tolerant and real-time applications, such as connected healthcare systems, smart farming, smart grid, etc.
Stability of 𝚤canonical bases of irreducible finite type of real rank one
Authors: Watanabe Hideya
Published: March 2023

It has been known since their birth in Bao and Wang’s work that the

ı
\imath

canonical bases of

ı
\imath

quantum groups are not stable in general. In the author’s previous work, the stability of

ı
\imath

canonical bases of certain quasi-split types turned out to be closely related to the theory of

ı
\imath

crystals. In this paper, we prove the stability of

ı
\imath

canonical bases of irreducible finite type of real rank

1
1

, for which the theory of

ı
\imath

crystals has not been developed, by means of global and local crystal bases.
Early Antiretroviral Therapy Not Associated With Higher Cryptococcal Meningitis Mortality in People With Human Immunodeficiency Virus in High-Income Countries: An International Collaborative Cohort Study
Authors: Ingle Suzanne M , Miro Jose M , May Margaret T , Cain Lauren E , Schwimmer Christine , Zangerle Robert , Sambatakou Helen , Cazanave Charles , Reiss Peter , Brandes Vanessa , Bucher Heiner C , Sabin Caroline , Vidal Francesc , Obel Niels , Mocroft Amanda , Wittkop Linda , d'Arminio Monforte Antonella , Torti Carlo , Mussini Cristina , Furrer Hansjakob , Konopnicki Deborah , Teira Ramon , Saag Michael S , Crane Heidi M , Moore Richard D , Jacobson Jeffrey M , Mathews W Chris , Geng Elvin , Eron Joseph J , Althoff Keri N , Kroch Abigail , Lang Raynell , Gill M John , Sterne Jonathan A C
Published: March 2023

Background

Randomized controlled trials (RCTs) from low- and middle-income settings suggested that early initiation of antiretroviral therapy (ART) leads to higher mortality rates among people with HIV (PWH) who present with cryptococcal meningitis (CM). There is limited information about the impact of ART timing on mortality rates in similar people in high-income settings.

Methods

Data on ART-naive PWH with CM diagnosed from 1994 to 2012 from Europe/North America were pooled from the COHERE, NA-ACCORD, and CNICS HIV cohort collaborations. Follow-up was considered to span from the date of CM diagnosis to earliest of the following: death, last follow-up, or 6 months. We used marginal structural models to mimic an RCT comparing the effects of early (within 14 days of CM) and late (14–56 days after CM) ART on all-cause mortality, adjusting for potential confounders.

Results

Of 190 participants identified, 33 (17%) died within 6 months. At CM diagnosis, their median age (interquartile range) was 38 (33–44) years; the median CD4+ T-cell count, 19/μL (10–56/μL); and median HIV viral load, 5.3 (4.9–5.6) log10 copies/mL. Most participants (n = 157 [83%]) were male, and 145 (76%) started ART. Mimicking an RCT, with 190 people in each group, there were 13 deaths among participants with an early ART regimen and 20 deaths among those with a late ART regimen. The crude and adjusted hazard ratios comparing late with early ART were 1.28 (95% confidence interval, .64–2.56) and 1.40 (.66–2.95), respectively.

Conclusions

We found little evidence that early ART was associated with higher mortality rates among PWH presenting with CM in high-income settings, although confidence intervals were wide.
Forecasting constraints on the mean free path of ionizing photons at z ≥ 5.4 from the Lyman-α forest flux autocorrelation function
Authors: Wolfson Molly , Hennawi Joseph F , Davies Frederick B , Oñorbe Jose
Published: March 2023

Fluctuations in Lyman-α (Ly α) forest transmission towards high-z quasars are partially sourced from spatial fluctuations in the ultraviolet background, the level of which are set by the mean free path of ionizing photons (λmfp). The autocorrelation function of Ly α forest flux characterizes the strength and scale of transmission fluctuations and, as we show, is thus sensitive to λmfp. Recent measurements at z ∼ 6 suggest a rapid evolution of λmfp at z > 5.0 which would leave a signature in the evolution of the autocorrelation function. For this forecast, we model mock Ly α forest data with properties similar to the XQR-30 extended data set at 5.4 ≤ z ≤ 6.0. At each z, we investigate 100 mock data sets and an ideal case where mock data matches model values of the autocorrelation function. For ideal data with λmfp = 9.0 cMpc at z = 6.0, we recover $\lambda _{\text{mfp}}=12^{+6}_{-3}$ cMpc. This precision is comparable to direct measurements of λmfp from the stacking of quasar spectra beyond the Lyman limit. Hypothetical high-resolution data leads to a $\sim 40~{{\ \rm per\ cent}}$ reduction in the error bars over all z. The distribution of mock values of the autocorrelation function in this work is highly non-Gaussian for high-z, which should caution work with other statistics of the high-z Ly α forest against making this assumption. We use a rigorous statistical method to pass an inference test, however future work on non-Gaussian methods will enable higher precision measurements.
A Scoring System to Select the Candidates for Adjuvant Chemotherapy Alone in High-Risk Early-Stage Cervical Cancer Patients With Pelvic Lymph Node Metastases After Surgery
Authors: Yang Xi-Lin , Yang Feng-Leng , Wang Na , Zhang Yue-Er , Kou Ling-Na , Wu Da-Jun , Luo Yi
Published: March 2023

Background:

The aim was to build a risk scoring system to guide the adjuvant treatment for early-stage cervical cancer patients with pelvic lymph node (LN) metastases after surgery.

Methods:

A cohort of 1213 early-stage cervical cancer patients with pelvic LN metastases (T1-2aN1M0) were selected from the NCI SEER database, of which 1040 patients received adjuvant external beam radiotherapy concurrent with chemotherapy (EBRT+Chemo) and 173 patients received adjuvant chemotherapy alone. The Cox regression analysis was applied to identify the risk factors associated with worse survival. The exp (β) of each independent risk factors from multivariate analysis was assigned to develop the risk scoring system. The total cohort was divided into different risk subgroups accordingly and the efficacy of different adjuvant modalities in each risk subgroups was compared.

Results:

The patients were divided into 3 risk subgroups (Low-risk: total score <7.20, Middle-risk:7.20≤ total score≤ 8.40, High-risk: total score<8.40) based on the scoring system incorporating 5 independent risk factors. The survival analysis suggested that low-risk (hazard ratio [HR]=1.046, 95% CI: 0.586-1.867; P=0.879) and middle-risk patients (HR=0.709, 95% CI: 0.459-1.096; P=0.122) could not benefit more from EBRT+Chemo than Chemo alone. However, EBRT+Chemo remained the superiority to Chemo alone in the high-risk subgroup (HR=0.482, 95% CI: 0.294-0.791; P=0.003).

Conclusion:

A risk scoring system has been built to direct the adjuvant treatment for early-stage cervical cancer patients with pelvic LN metastases after surgery, where Chemo alone was totally enough for low-risk and middle-risk patients stratified by the model while EBRT+Chemo was still recommended for patients in the high-risk subgroup.
Gender Differences in Clinical Practice and Medicare Reimbursement Among Mohs Surgeons
Authors: Motosko Catherine C. , Waldman Abigail , Stevenson Mary L. , Council M. Laurin
Published: March 2023

OBJECTIVE

To evaluate Medicare reimbursement and clinical activity between male and female dermatologic surgeons.

MATERIALS AND METHODS

A retrospective review of the Medicare Provider Utilization and Payment data from 2018 was performed for all dermatologists performing MMS. Provider gender, place of service, number of services, and average payment per service was recorded for all relevant procedure codes.

RESULTS

Women represented 31.5% of the 2,581 surgeons who performed MMS in 2018. Women were paid significantly less than men (mean difference, -$73,033). On average, women performed 123 fewer cases than their male counterparts. When surgeons were stratified by productivity, remuneration was the same.

CONCLUSION

Remuneration from CMS was disparate between male and female dermatologic surgeons, which may be attributed to submission of fewer charges by women. Further efforts are necessary to better evaluate and address causes for this discrepancy, because greater parity of opportunity and pay would greatly benefit this subspecialty of dermatology.
A Cost Comparison Between Mohs Micrographic Surgery and Conventional Excision for the Treatment of Head and Neck Melanomas In Situ and Thin Melanomas
Authors: Nugent Shannon T. , Cheng Brian , Illenberger Nicholas , Wu Yaxin , Russell Louise B. , Miller Christopher J. , Zullo Shannon W. , Perz Allison , Fix William C. , Etzkorn Jeremy R. , Sobanko Joseph F.
Published: March 2023

BACKGROUND

Variation in operative setting and surgical technique exists when treating specialty site melanomas. There are limited data comparing costs among surgical modalities.

OBJECTIVE

To evaluate the costs of head and neck melanoma surgery performed with Mohs micrographic surgery or conventional excision in the operating room or office-based settings.

METHODS

A retrospective cohort study was performed on patients aged 18 years and older with surgically treated head and neck melanoma in 2 cohorts, an institutional cohort and an insurance claims cohort, for the years 2008–2019. The primary outcome was total cost of care for a surgical encounter, provided in the form of insurance reimbursement data. A generalized linear model was used to adjust for covariates affecting differences between treatment groups.

RESULTS

In the institutional and insurance claims cohorts, average adjusted treatment cost was highest in the conventional excision-operating room treatment group, followed by the Mohs surgery and conventional excision-office setting (p < .001).

CONCLUSION

These data demonstrate the important economic role the office-based setting has for head and neck melanoma surgery. This study allows cutaneous oncologic surgeons to better understand the costs of care involved in head and neck melanoma treatment. Cost awareness is important for shared decision-making discussions with patients.
Tranexamic acid-associated intrathecal toxicity during spinal anaesthesia
Authors: Patel Santosh
Published: March 2023

Therapeutic use of tranexamic acid (TXA) to minimise blood loss is common during a wide range of surgical procedures. This review aims to explore the clinical features of the accidental intrathecal administration of TXA and to identify contributory factors that might prevent future incidents. The author searched published reports of accidental intrathecal administration of TXA using Medline and Google Scholar databases from July 2018 to September 2022, including error reports in any language but excluding errors via nonintrathecal routes. The human factors analysis classification system (HFACS) framework was used to examine and classify the human and systemic factors that contributed to the errors. Twenty-two errors of accidental intrathecal administration were reported during the search period. The analysis showed that the outcome was death in eight patients (36%) and permanent harm in four (19%). The fatality rate was higher among female individuals (6/13 versus 2/8 male individuals). Two-thirds of errors (15/22) occurred during orthopaedic surgery (10) and lower segment caesarean sections (5). Nineteen of 21 patients developed refractory or super refractory status epilepticus, requiring mechanical ventilation and intensive care for 3 days to 3 weeks for those who survived the initial few hours. Severe sympathetic stimulation resulting in refractory ventricular arrhythmias was the final event in some patients, with death within a few hours. Lack of familiarity with clinical characteristics caused delayed diagnosis or confusion with other clinical conditions. A proposed plan to manage intrathecal TXA toxicity is presented, including immediate cerebrospinal fluid lavage; however, there is no specific approach. The HFACS suggested mistaking look-alike TXA ampoules for local anaesthetic was the predominant cause. The author concludes that inadvertent intrathecal TXA is associated with mortality or permanent harm in more than 50% of patients. The HFACS demonstrates that all errors are preventable.
An Algorithm for Prevention of Unsightly Facial Scars Considering the Newest Research Insights
Authors: Feinendegen Dominik L. , Grubnik Alexandra , Feinendegen Sandra Y.
Published: March 2023

Background:

Unsightly scars after facial surgery might be a worry for patients and surgeons alike. To prevent unfavorable scars after facial operations, it is inevitable for the surgeon to adhere to different principles and to follow an algorithm: patient assessment, incision planning, surgical technique, suture material, and postoperative scar management. A defined knowledge about the pathophysiology of wound healing is required. The aim of this report is to serve as a teaching purpose and to verify the well-known empirical practices in scar prevention with the corresponding explanatory research. Based on these findings, the suggestion of an appropriate algorithm for the best scar management will be elaborated.

Methods:

This article elucidates the basics of unsightly scar prevention and the concomitant scientific proofs in detail by reviewing the literature and newest research published in PubMed.

Results:

The preoperative, intraoperative, and postoperative guidelines for the achievement of acceptable facial scars will be distinguished regarding the valid state of knowledge. Special attention is drawn to the “flat incision technique” as the first surgical step. Based on the newest research, an algorithm of the important preoperative, intraoperative, and postoperative features to achieve scar improvement is presented.

Conclusions:

To prevent unsightly facial scars, a well-defined algorithm must be followed. In summary, three well-established, empirically proven measures are documented now by the equivalent physiological scientific proof: (1) the flat incision technique, (2) the wound closure with maximal tension reduction, and (3) the postoperative scar management with further tension reduction and more moisturizing of the scar.