bluuebunny/crossref_metadata_2025 huggingface dataset:
Nonvolatile reconfigurable broadband photodiodes based on BP/α-In2Se3 ferroelectric p–n junctions
Authors: Zhu Chuanchao , Wang Yanrong , Wang Feng , Yang Jia , Zhan Xueying , Fang Liang , Wang Zhenxing , He Jun
Published: February 2022

Imagers with pre-processing functions, such as image recognition and classification, contrast enhancement, and noise reduction, play a critical role in the neuromorphic visual system. Optoelectronic plasticity is a prerequisite to achieve these functions. In this study, we demonstrate a nonvolatile reconfigurable broadband photodetector based on a ferroelectric heterostructure composed of BP (black phosphorus)/α-In2Se3. The plasticity of the device comes from the ferroelectric polarization of α-In2Se3 that can tune the built-in potential of the p–n junction. As a result, the rectification ratio and responsivity increase almost one order when changing the gate voltage pulse from +16 V to −16 V. Due to the introduction of BP, the device has a wide spectral response covering 473–1550 nm. In addition, our devices show excellent performance in terms of a high responsivity of up to 4.73 × 104 A/W, a large specific detectivity of ∼2.09 × 1012 Jones, a high external quantum efficiency of 9.21 × 106%, and a notable photo-on-off ratio of 4.82 × 103. Due to its high performance, reconfigurability, and broadband response, our device shows considerable potential in neuromorphic visual systems even in the infrared region.
Reducing solid conduction in electrothermally driven MEMS Pirani gauge using integrated polymeric thin film
Authors: Garg Manu , Arya Dhairya S. , Kumar Sushil , Chiu Yi , Singh Pushpapraj
Published: February 2022

An electrothermally driven MEMS Pirani gauge with an integrated polymeric (SU-8) thin film is proposed. The structured architecture utilizes the miniaturization advantage of microbridge-type Pirani gauges while combining the lower conduction losses of membrane-based gauges. The integrated polymeric film is highly effective in providing mechanical strength to the metallic resistor and in reducing solid conduction loss to the substrate. Consequently, the dynamic range is extended, and the proposed device shows a wide dynamic range from 40 to 105 Pa. Moreover, biased at 2 mA, the average power consumption of the device is 0.5 mW. Experimental results are in proximity with the simulated results, and the overall footprint of the device is 35 × 7 μm2. The post-CMOS compatible polymer-based Pirani gauge can be used for hermetic characterization for more than three decade-Pa range. The experimentally characterized fusing trend shows that the critical current density for safer operation of the device is 30 mA/μm2.
Laser control of a dark vibrational state of acetylene in the gas phase—Fourier transform pulse shaping constraints and effects of decoherence
Authors: Aerts Antoine , Kockaert Pascal , Gorza Simon-Pierre , Brown Alex , Vander Auwera Jean , Vaeck Nathalie
Published: February 2022

We propose a methodology to tackle the laser control of a non-stationary dark ro-vibrational state of acetylene (C2H2), given realistic experimental limitations in the 7.7 μm (1300 cm−1) region. Simulations are performed using the Lindblad master equation, where the so-called Lindblad parameters are used to describe the effect of the environment in the dilute gas phase. A phenomenological representation of the parameters is used, and they are extracted from high-resolution spectroscopy line broadening data. An effective Hamiltonian is used for the description of the system down to the rotational level close to experimental accuracy. The quality of both the Hamiltonian and Lindblad parameters is assessed by a comparison of a calculated infrared spectrum with the available experimental data. A single shaped laser pulse is used to perform the control, where elements of optics and pulse shaping using masks are introduced with emphasis on experimental limitations. The optimization procedure, based on gradients, explicitly takes into account the experimental constraints. Control performances are reported for shaping masks of increasing complexity. Although modest performances are obtained, mainly due to the strong pulse shaping constraints, we gain insights into the control mechanism. This work is the first step toward the conception of a realistic experiment that will allow for population characterization and manipulation of a non-stationary vibrational “dark” state. Effects of the collisions on the laser control in the dilute gas phase, leading to decoherence in the molecular system, are clearly shown.
Generation of plasma electron halo by a charged particle beam in a low density plasma
Authors: Gorn A. A. , Lotov K. V.
Published: February 2022

Breaking of a plasma wave driven by a long beam of charged particles results in electron jets escaping from the plasma column and forming an electron halo. The halo is accompanied by a strong radial electric field around the plasma, which can distort the trajectories of relativistic charged particles that propagate near the plasma border or are injected into the plasma wave. We study the mechanisms of wave breaking and halo formation when the beam and plasma densities are comparable. If the plasma density is less than or of the order of the beam density, the wavebreaking is well described by a semi-analytical model, which agrees with simulations and allows us to calculate the position of wavebreaking points and determine the regions around the plasma column occupied by the halo.
Solid experimental evidence for reverse intersystem crossing from high-lying triplet states: A case study on hot exciton mechanism in OLEDs
Authors: Chen Liangjian , Qiao Xianfeng , Xiao Shu , Chi Jiajin , Yang Dezhi , Ma Dongge , Ma Yuguang
Published: February 2022

Hot excitons have been attempted to utilize the triplet excitons in organic light-emitting diodes (OLEDs). Due to the transient and dark nature of high-lying triplet states (Tn, n ≥ 2), the normative methods to characterize the hot exciton mechanism have not been thoroughly developed. Here, a normal technique combining transient photoluminescence and magneto-electroluminescence (MEL) measurements has been proven to visualize the reverse intersystem crossing process from T2 to S1 states in 5,6,11,12-tetraphenylnaphthacene (rubrene) molecules. Rubrene is chosen as a model system since its T1 is far below S1 and T2 is resonant with S1. This hot exciton process opens an additional route, marked as Dexter energy transfer channel (CT3→T2→S1, DET channel), together with the well-known Förster resonance energy transfer channel (CT1→S1) to transfer the host energy to the guest. With proper approximates, the DET channel assisted by the hot excitons process can contribute about 46.6% excitons to rubrene S1 and 83.4% rubrene emission in rubrene-doped devices. These studies set an in situ normative characterizing frame to visualize the hot excitons process in OLEDs.
Uncovering surface plasmon optical resonances in nanohole arrays through interferometric photoemission electron microscopy
Authors: Crampton Kevin T. , Joly Alan G. , El-Khoury Patrick Z.
Published: February 2022

The role of surface plasmon polaritons (SPPs) in nanohole array optical extinction spectra is explored using a time-resolved technique capable of isolating the air/metal interfacial SPP contribution to the typical Fano profile in optical transmission curves. A pair of interferometrically locked broad-band femtosecond pulses is used to launch SPPs from lithographically patterned plasmonic nanohole arrays. SPPs launched in the co- and counter-propagating directions are probed using a third probe pulse in a photoemission electron microscope. Using this approach, we record interferometric SPP–SPP linear autocorrelations that selectively report on the resonances of SPPs launched from arrays of varying pitches and hole diameters. Aside from advancing an approach to selective SPP spectroscopy, we illustrate that resonant coupling in the counter-propagating direction may be exploited to control the spatial, temporal, and spectral characteristics of SPPs. For the counter-propagating direction, we show that tuning the array pitch near the fundamental plasmon resonance generates color-tuned (∼770–820 nm), narrow bandwidth SPPs, and the bandwidth may be controlled by changing the ratio of pitch to hole diameter. The SPP resonances we recover through Fourier transforms of the interferometric autocorrelations shed light on the classical problem of Fano interference in nanohole array extinction spectra.
Doping and compensation in heavily Mg doped Al-rich AlGaN films
Authors: Bagheri Pegah , Klump Andrew , Washiyama Shun , Hayden Breckenridge M. , Kim Ji Hyun , Guan Yan , Khachariya Dolar , Quiñones-García Cristyan , Sarkar Biplab , Rathkanthiwar Shashwat , Reddy Pramod , Mita Seiji , Kirste Ronny , Collazo Ramón , Sitar Zlatko
Published: February 2022

Record low resistivities of 10 and 30 Ω cm and room-temperature free hole concentrations as high as 3 × 1018 cm−3 were achieved in bulk doping of Mg in Al0.6Ga0.4N films grown on AlN single crystalline wafer and sapphire. The highly conductive films exhibited a low ionization energy of 50 meV and impurity band conduction. Both high Mg concentration (>2 × 1019 cm−3) and low compensation were required to achieve impurity band conduction and high p-type conductivity. The formation of VN-related compensators was actively suppressed by chemical potential control during the deposition process. This work overcomes previous limitations in p-type aluminum gallium nitride (p-AlGaN) and offers a technologically viable solution to high p-conductivity in AlGaN and AlN.
Study of the performance of nitrogen-doped modified activated carbon as catalyst carrier for the selective catalytic reduction of NO with NH3 at low temperatures
Authors: Feng Xiangdong , Liu Shanjian , Li Yongjun , Kong Ranran , He Jianjie
Published: February 2022

Nitrogen-doped modified activated carbons (ACs) were prepared from coconut shell, date shell and almond shell using the urea modification method. NO tests of NH3 selective catalytic reduction (NH3-SCR) were conducted to evaluate the efficiency of different types of nitrogen-doped modified AC as denitration catalyst carriers between 50–220°C. Both AC and nitrogen-doped modified AC had catalytic effects on NO conversion; the nitrogen-doped modified AC had high denitrification activity in the low-temperature region, and NAC1-10 achieved an NO conversion rate of 65.7% at 50°C. The low-temperature denitrification activity of urea-modified AC was twice that of the untreated AC at all temperatures. The O2 concentration in the SCR reaction system had a significant effect on the NO conversion rate of the nitrogen-doped modified AC. As the O2 concentration increased from 0 to 1 vol%, the NO conversion rate increased rapidly from 22 to 65% and remained stable at 65%. A series of characterisation tools were used to determine the structure and physicochemical properties of the nitrogen-doped modified AC, including BET, XRD, elemental analysis, and FTIR. Nitrogen-doped AC showed good air velocity adaptability and low-temperature stability, suggesting that it is a promising carrier for NH3-SCR catalysts.
Exploring the interplay of biotic interactions and salinity stress in freshwater invertebrate assemblages: a response to Kefford
Authors: Chessman Bruce C.
Published: February 2022

Controlled mesocosm experiments can add substantially to our knowledge of the influence of environmental factors on freshwater assemblages by partitioning the possible effects of different drivers. Reporting results of such an experiment, Bray et al. (2019) concluded that effects of salinity on salt-sensitive stream invertebrates were substantially modified by interspecific biotic interactions with salt-tolerant invertebrates from a high-salinity stream. Chessman (2021) questioned this conclusion on three grounds: (1) confounding of the experimental design, (2) lack of evidence that purported diverse effects of biotic interactions were beyond mere stochastic variation, and (3) absence of mechanistic explanations for supposed effects grounded in organism biology and ecology. Chessman (2021) also conducted an independent statistical analysis of publicly available data from the experiment, which did not support the study’s conclusions. Kefford et al. (2022) dispute Chessman’s (2021) findings by analysing previously unpublished data from the experiment, which they claim demonstrates that the experimental design was not confounded, and criticise Chessman’s (2021) statistical analysis. Here, I respond to their new analysis and criticisms, explaining why they do not dispel any of the concerns expressed by Chessman (2021).
A ‘joint’ approach: design, implementation and preliminary outcomes of an early conservative knee and hip osteoarthritis service in northern New South Wales, Australia
Authors: Campbell Brayden , Schultz Luke , Bryant Evan , Tsung Jason D. , Lynam Brett , Stephens Alexandre S.
Published: February 2022

Australia is facing a growing burden of knee and hip osteoarthritis (OA). To address this demand in northern New South Wales, a community health-based conservative OA joint management service was established in the Tweed Valley. This paper describes the design, implementation and initial evaluation of the service. Following the principles of clinical redesign, a diagnostic phase involving consultation with key stakeholders revealed several issues. OA patients could wait up to 9 months for review by orthopaedic specialist following GP referral and received limited information on how to conservatively manage their conditions. GPs were constrained by short consultations and had limited knowledge of the latest recommendations for the conservative treatment of OA. GPs also highlighted the limitations of outdated fax systems for communication, noting their preference for secure electronic messaging. Based on these findings, the Tweed Knee and Hip Arthritis Service was established. For patients not on a waiting list for surgery, the service provides evidence-based conservative management for knee or hip OA involving standardised assessment, education, exercise, self-management strategies and regular review. An analysis of a foundational cohort of patients demonstrated improvements in a suite of validated and standardised measures for pain and function, with improvements seen as early as 1 month and sustained for 6 months. The study findings support the introduction of integrated conservative OA management models of care directly available to primary healthcare providers.
Biocompatible surface functionalization architecture for a diamond quantum sensor
Authors: Xie Mouzhe , Yu Xiaofei , Rodgers Lila V. H. , Xu Daohong , Chi-Durán Ignacio , Toros Adrien , Quack Niels , de Leon Nathalie P. , Maurer Peter C.
Published: February 2022

Significance

Diamond-based quantum sensing enables nanoscale measurements of biological systems with unprecedented sensitivity. Potential applications of this emerging technology range from the investigation of fundamental biological processes to the development of next-generation medical diagnostics devices. One of the main challenges faced by bioquantum sensing is the need to interface quantum sensors with biological target systems. Specifically, such an interface needs to maintain the highly fragile quantum states of our sensor and at the same time be able to fish intact biomolecules out of solution and immobilize them on our quantum sensor surface. Our work overcomes these challenges by combining tools from quantum engineering, single-molecule biophysics, and material processing.
On the free rotation of a polarized spinning-top as a test of the correct radiation reaction torque
Authors: Duviryak A
Published: February 2022

The formula for dipole radiation reaction torque acting on a system of charges, and the Larmor-like formula for the angular momentum loss by this system, differ in the time derivative term which is the analogue of the Schott term in the energy loss problem. In the well-known textbooks this discrepancy is commonly avoided via neglect of the Schott term, and the Larmor-like formula is preferred. In the present paper both formulae are used to derive two different equations of motion of a polarized spinning-top. Both equations are integrable for the symmetric top and lead to quite different solutions. That one following from the Larmor-like formula is physically unplausible, in contrast to another one. This result is accorded with the reinterpretation of Larmor’s formula discussed recently in the pedagogical literature. It is appeared, besides, that the Schott term is of not only academic significance, but it may determine the behavior of polarized micro- and nanoparticles in nature or future experiments.
Pressure-induced Fermi resonance between fundamental modes in phthalic anhydride
Authors: Liu HaiRui , Chen YinQi , Liu Guangtao , Zhou Mi
Published: February 2022

In situ high-pressure Raman spectra of phthalic anhydride (PA) have been measured up to 16 GPa through diamond anvil cell technique. The results show that all the Raman bands are blue-shifted with the increase of pressure, accompanied by appearance of some new bands. A Fermi resonance phenomenon of the two Raman fundamental modes of PA at 773 cm−1 and 801 cm−1 is proposed at pressures above 6.6 GPa, where a possible first-order phase transition occurs. The pressure-induced changes of Fermi resonance parameters, e.g., intensity ratio, coupling coefficient and frequency gap of unperturbed transition, are discussed.
Study of digital/analog performance parameters of misaligned gate recessed double gate junctionless field-effect-transistor for circuit level application
Authors: Kumar Sandeep , Chatterjee Arun Kumar , Pandey Rishikesh
Published: February 2022

In this work, the effect of gate misalignment towards the source and drain ends for 20 nm recessed double gate junctionless field-effect-transistor (R_DGJLFET) have been studied on various digital and analog performance parameters from device to circuit level while setting the simulation set-up using 2D Silvaco ATLAS technology computer aided design (TCAD). With recessed silicon channel, the quantum confinement effects have been considered for channel thickness <7 nm. In comparison to conventional double gate junctionless FET (C_DGJLFET), the device exhibits lesser OFF-current, improved ON-to-OFF current ratio, better subthreshold slope (SS), and lower drain-induced-barrier-lowering (DIBL). Analogically, it has been found that the misaligned gate towards drain affects the digital and analog parameters more severely in comparison to gate misalignment towards the source end. However, the misaligned R_DGJLFET towards the drain end shows robustness in terms of SS and DIBL with smaller variations of ∼10.84% and ∼61.79%, respectively. Moreover, due to very low parasitic capacitances, the device shows lesser variations in different alternating current (AC) performance parameters namely, transconductance generation factor (TGF), unity gain frequency, and gain-bandwidth product in comparison to C_DGJLFET. With gate misalignment towards source the unity gain frequency, and gain-bandwidth improve by ∼9.67% and ∼19.9%, respectively whereas the TGF remains almost unaffected. Furthermore, to ensure the device capability in circuit application a complementary metal-oxide-semiconductor (CMOS) inverter and common-source (CS) amplifier based on R_DGJLFET have been designed. In contrast to C_DGJLFET based counterpart, the R_DGJLFET expresses its suitability for low-power digital applications with better noise margins and smaller short-circuit current in the CMOS inverter. In analog domain, the R_DGJLFET based CS amplifier shows an improved amplification factor of 4.75 in comparison to C_DGJLFET. This paper provides deep insight into the severity of gate misalignment towards source/drain for R_DGJLFET in both digital and analog domains from device to circuit level.
Buffer gas cooling of ions in radio-frequency traps using ultracold atoms
Authors: Trimby E , Hirzler H , Fürst H , Safavi-Naini A , Gerritsma R , Lous R S
Published: February 2022

Reaching ultracold temperatures within hybrid atom–ion systems is a major limiting factor for control and exploration of the atom–ion interaction in the quantum regime. In this work, we present results on numerical simulations of trapped ion buffer gas cooling using an ultracold atomic gas in a large number of experimentally realistic scenarios. We explore the suppression of micromotion-induced heating effects through optimization of trap parameters for various radio-frequency (rf) traps and rf driving schemes including linear and octupole traps, digital Paul traps, rotating traps and hybrid optical/rf traps. We find that very similar ion energies can be reached in all of them even when considering experimental imperfections that cause so-called excess micromotion. Moreover we look into a quantum description of the system and show that quantum mechanics cannot save the ion from micromotion-induced heating in an atom–ion collision. The results suggest that buffer gas cooling can be used to reach close to the ion’s groundstate of motion and is even competitive when compared to some sub-Doppler cooling techniques such as Sisyphus cooling. Thus, buffer gas cooling is a viable alternative for ions that are not amenable to laser cooling, a result that may be of interest for studies into cold controlled quantum chemistry and charged impurity physics.
Fermionic King model: critical masses resulting from the competition of quantum and evaporation effects
Authors: Velazquez L , Espinoza-Soliz I
Published: February 2022

We study the influence of evaporation (the escape of constituents) on the thermodynamics of a self-gravitating non-relativistic gas of fermions in the framework of Newtonian gravitation. For this purpose, it is reconsidered as the so-called fermionic King model introduced by Ruffini and Stella in the context of dark matter halos problems (1983 Astron. Astrophys.
119 3). As the usual King model, the present model predicts density profiles that drop to zero at a certain finite radius R, which is referred to as the tidal radius. Our interest is focused on the thermodynamics of this model at constant total mass M and constant tidal radius R. A special interest is devoted to study the incidence of mass on the collective phenomena of gravitational collapse and evaporation disruption. The underlying physics is driven by the Fermi mass M
F ∼ ℏ
6/G
3
m
8
R
3, which corresponds to the total mass of a self-gravitating degenerate Fermi gas of non-relativistic point particles with mass m, whose linear size is equal to the tidal radius R of evaporation. Numerical calculations predict three critical values for the total mass, M
1 > M
2 > M
3, which hallmark the thermodynamic stability. The lower bound

M

3

≃

1

4

M

F

is a critical value of the total mass below the which the system gravitation is unable to confine its constituents, so that the system with total mass M < M
3 undergoes an evaporation disruption. The other bounds, M
2 ≃ 90.9M
F and M
1 ≃ 8.9 × 106
M
F, are critical values that hallmark the continuous (or discontinuous) character of the microcanonical phase transition associated with gravothermal collapse and the presence of states with negative heat capacities.
A survival model to explain the statistical properties of multimodal mobility
Authors: Mizzi C , Fabbri A , Colombini G , Bertini F , Bazzani A
Published: February 2022

The statistical properties of human mobility have been studied in the framework of complex systems physics. Taking advantage of the new datasets made available by the information and communication technologies, the distributions of mobility path lengths and of trip durations have been considered to discover the fingerprints of complexity characters, but the role of the different transportation means on the statistical properties of urban mobility has not been studied in depth. In this paper, we cope with the problem of the existence of universal features for pedestrian, bike and vehicular urban mobility. In particular, we propose the use of travel time as the universal energy for the mobility and we define a simple survival model that explains the travel time distribution of the different mobility types. The analysis is performed in the metropolitan area of Bologna (Italy), where GPS datasets were available on individual trips using different transport means. Our results could be helpful for the realization of multimodal sustainable mobility in future cities, compatible with the citizen’s propensities to use different transport means.
The Design and Implementation of Control and Driving system with Double Position Feedback for Submarine Steering
Authors: Tian Guanzhi , Jiang Liting , Yuan Liwei , Xu Zhishu , Zhang Yiqi , Li Chunyu
Published: February 2022

With the well improvement of motor and power electronic technology, the technology of Electro-mechanical actuator (EMA)has come into a new stage. A high-reliability driving and controlling technology with a double redundancy feedback loop is described in this paper. In this method, the position of electromechanical actuator and the resolver position of motor can be back up for each other by some compensate algorithms. This method can improve the reliability of the control system without extra hardware and increasing cost.
Parallel operation simulation of medium voltage diesel emergency power supply vehicles
Authors: Xie Rui , Ge Xinyuan , Hu Ripeng , Zhu Junpeng , Xie Bin
Published: February 2022

The large-scale emergency load demand improves the requirements of distribution network for emergency power capacity, and the working condition of multi-engine parallel operation of medium voltage diesel emergency power supply vehicles also arises. In order to solve the difficulty of parallel simulation of medium voltage diesel emergency power supply vehicles, this paper establishes the simulation model of medium voltage diesel emergency power supply vehicles by analyzing the mathematical models of internal components. According to the parameter conditions of parallel operation, the parallel controller is designed. Finally, the multi-engine parallel system model of medium voltage diesel emergency power supply vehicles is built by using Matlab / Simulink, and the parallel operation simulation of medium voltage diesel generator vehicles is completed.
Amino-Modified Hollow Mesoporous Silica Microspheres Loaded with Cresol Red-Boric Acid for Potent Reversible Thermochromic Performance
Authors: Yu Tingting , Wang Xu , Cheng Liang , Hu Yuehang , Wang Haoya , Wang Hao
Published: February 2022

In this study, two reversible thermochromic composites were obtained, hollow mesoporous silica (HMS) and amino group-modified hollow mesoporous silica (HMS-NH2) microspheres loaded with cresol red-boric acid (CR-BA), respectively. Owing to the rigid structure of hollow interior and mesoporous shell layers, CR-BA was easily encapsulated into a relatively high loading capacity micro-carrier. The composites analysed were characterized by Fourier transform infrared spectroscopy transmission electron microscopy, scanning and transmission electron microscopy and dynamic light scattering. By amino functionalization, a more obvious thermal colour-change was observed in HMS-NH2 loaded with CR-BA. In addition, both HMS and HMS-NH2 loaded with CR-BA illustrated a sever colour reversibility, which were 5min and 3min respectively.
Synthesis and Analysis of a Viscosity Modifying Admixture based on Acrylamide and 2-Acrylamide-2-methylpropanesulfonic acid
Authors: Ni Tao , Song Xin , Wang Yongmei , Feng Ke , Ng Serina , Liu Zhaoyang
Published: February 2022

Viscosity modifying admixture (VMA) can be employed to avoid the segregation of concrete. Here, we present a type of viscosity modifying agent (B2), prepared by free radical polymerization between acrylamide (AM) and 2-acrylamide-2-methylpropane sulfonic acid (AMPS). The structure and composition were characterized by FT-IR, NMR and light scattering. Hydroxy-propyl-methyl cellulose (HPMC) was used as a comparison to determine the suitability of B2 as a VMA. The results show that B2 is superior to HPMC, and can improve not only the homogeneity and bleeding resistancy, but also increase the compressive strengths of the concrete by 4 to 5 MPa across all testing periods, up to 28 days. A highlight of this admixture is the effective regeneration of nonuseable concrete to its non bleeding state with delayed addition. Finally, a mechanistic analysis of the viscosifying effect, which induced the increase in compressive strength is postulated in this article.
Preparation of amphiphilic block copolymers by Reversible Addition Fragmentation Chain Transfer polymerization
Authors: Hu Na
Published: February 2022

Polystyrene macromolecular chain transfer agent (PS-CTA) was firstly synthesized by RAFT of styrene (St) in THF using benzyl dithiobenzoate (BDTB) as chain transfer agent and azobisisobutyronitrile (AIBN) as initiator. It was found that the molar ratio of monomers to chain transfer agents and reaction time had obvious effects on the molecular weight of PS-CTA, and the distribution of molecular weight (M
w/M
n ) decreases with the increase of the ratio of chain transfer agent to initiator by using gel permeation chromatography (GPC). The amphiphilic block copolymers polystyrene-b-poly(4-vinylpyridine) (PS-b-P4VP) were synthesized using PS-CTA by RAFT. The structure, glass transition temperature (Tg) and molecular weight of the diblock copolymer were characterized by nuclear magnetic resonance (1H-NMR), differential scanning calorimetry (DSC) and gel permeation chromatography (GPC). The results showed that the structure of PS-b-P4VP was the target product. The segment ratio of PS-b-P4VP could be effectively controlled by changing the polymerization conditions in a large range.
Surface modification of Ti6Al7Nb employing pure waterjet and abrasive waterjet polishing for implant application: comparison study
Authors: N Pradeep , Sastry C Chandrasekhara , Brandão Lc , Coelho RT , Bairapudi Anil , Muthu Manickam MA , Rahman Hafeezur , Patil Sandeep
Published: February 2022

Natural bones in vertebrates are replaced with implants when it fails under fatigue/impact loading conditions. The implants surface roughness is a vital parameter that enhances the osseointegration rate owing to mechanical stability by firm anchoring between the implant and the bone tissue. In this research article, surface modification of Ti6Al4Nb by the action of impingement erosion was executed under two conditions (i) Waterjet polishing (WP) without abrasives; (ii) Abrasive waterjet polishing (AWP) with biocompatible abrasives and studied in correlation to MRR and average surface roughness. The bio abrasives were made in a laboratory that endorses the bone healing characteristics availing 85% hydroxyapatite (HAp) and 15% yttrium stabilized zirconia. SEM, EDS, XRD, AFM and Non-contact surface roughness measurements were used to study the surface morphology of the bio-abrasives and the AWP surface. Experimentally the WP resulted in 73% more material removal rate and with higher average surface roughness Ra by 50% when compared to the AWP. The biocompatibility of Ti6Al4Nb post AWP was found to be favourable with more live cells after performing the MG63 Cell assay for the optimal exp run #11 obtained via the desirability function algorithm.
Optimisation of Corrosion behaviour and hardness of Ni-B4C Composite coated AZ31 Mg alloy using RSM
Authors: Venses G , Sivapragash M , Sasi Kumar T , Michael Thomas Rex F
Published: February 2022

The optimisation of process parameters in the electroplating process is imperative to improve the effectiveness of coating that meets the industry’s requirements. The present study analyses the influence of the electroplating parameters such as bath temperature, current intensity, and plating time on the hardness and corrosion properties of AZ31 Mg alloy. A preliminary electroplating coating was initially done on the AZ31 Mg alloy with zinc and copper. Subsequently, the AZ31 Mg alloy is coated with Ni-B4C composite by electroplating. Response Surface Methodology (RSM) is used to find the optimum settings for the parameters by minimising the corrosion loss and maximising the hardness. The quadratic regression models were developed for the responses based on the experiments conducted as per the Box-Behnken design method. Scanning Electron Microscopy (SEM), XRD analyses are used to investigate the effectiveness of the Ni–B4C composite coating on AZ31 Mg alloy. It is revealed from the results that the maximum hardness of 140 HV and minimum corrosion mass loss of 0.583 mg cm−2 was obtained for the optimal parameters.
Mechanical, morphological and thermal analysis of unidirectional fabricated sisal/flax hybrid natural fiber composites
Authors: Sundeep Dola , Varadaraj Eswaramoorthy K , Ephraim S Daniel , Sastry C Chandrashekara , Krishna A Gopala
Published: February 2022

We report the spectroscopic, thermal, and mechanical outcomes of epoxy reinforced sisal/flax (S/F) hybrid natural fiber composites. This work is intended to enhance the mechanical and thermal properties of the sisal fibers in addition to flax fibers. In recent years, natural fiber composites gained inclusive credit as a supernumerary to conventional synthetic composites for their superior ecological properties. Five different varieties of composite slabs i.e., 60% epoxy matrix and 40% of sisal/flax fibers were fabricated unidirectionally through a simple hand layout method by varying sisal and flax ratio as (40/0, 30/10, 20/20, 10/30, and 0/40) with a constant weight fraction as 0.4Wf. The x-ray diffraction analysis was performed on the 20 S/20 F specimen and the crystallinity index is calculated as 42.84%. The spectroscopic and thermal studies were conducted on the 20 S/20 F sample and the chemical imprint of the composite is revealed by the strong peaks of cellulose, hemicellulose, and lignin along with amorphous and crystalline content of the FTIR data and is confirmed through the XRD data. The addition of flax fibers to sisal fibers showed a constructive improvement of thermal stability which is shown by the TG/DTA graph. In a three-stage degradation of sample, a maximum is observed at 334 °C. The tensile, flexural, and impact tests of all the fabricated composite samples are performed and ultimate tensile strength of 165.2 N/mm2 for the 40 S/0 F composite with an elongation of 9.2% is noted. The ultimate flexural stress of 8.1 N mm−2 is observed in composite 10 S/30 F and composite 10 S/30 F has an excellent ability to absorb impact force of 1.2 J energy. Based on the above results the manufactured composites exhibited higher thermal and mechanical properties showing a unique characteristic for different concentrations of flax fibers. Thus, the developed composites can be used individually for various applications based on the requirement of the end-user.
Effect of LN2 and CO2 Coolants in hard turning of AISI 4340 steel using tungsten carbide tool
Authors: Gowthaman B , Boopathy S Rajendra , Kanagaraju T
Published: February 2022

Recently, Cryogenic cooling has witnessed a significant role in improving efficiency, increasing the quality of machined parts, and developing a techno-economic and eco-friendly acceptable methodology in the machining of components. This study deals with the effect of hardened AISI 4340 steel at 48 HRC against uncoated WC cutting tool analysed through the use of dry, cryogenic liquid nitrogen (Cryo-LN2) and cryogenic liquid carbon dioxide (Cryo-LCO2) cooling environments. The input parameters for this hard turning condition include cutting velocity, feed rate, and depth of cut. A study of the machining performance of cutting temperature, surface roughness, material side flow, flank wear, microhardness, and chips morphology have also been made. The experiment results revealed the effective lowering of the cutting temperature, better surface roughness and reduced flank wear for LCO2 and LN2 coolant by cryogenic cooling against dry cutting condition. Compared to dry and cryogenic LCO2 cutting environments, the machined zone of a cryogenic LN2 exhibited the highest microhardness value. The main reason for this was the decrease in the thermal softening effect. Overall, the performance of the cryogenic LN2 environment condition was effective and efficient in the turning process compared to dry and cryogenic LCO2.
Revealing room temperature ferromagnetism in exfoliated Fe5GeTe2 flakes with quantum magnetic imaging
Authors: Chen Hang , Asif Shahidul , Whalen Matthew , Támara-Isaza Jeyson , Luetke Brennan , Wang Yang , Wang Xinhao , Ayako Millicent , Lamsal Saurabh , May Andrew F , McGuire Michael A , Chakraborty Chitraleema , Xiao John Q , Ku Mark J H
Published: February 2022

Van der Waals (vdW) material Fe5GeTe2, with its long-range ferromagnetic ordering near room temperature, has significant potential to become an enabling platform for implementing novel spintronic and quantum devices. To pave the way for applications, it is crucial to determine the magnetic properties when the thickness of Fe5GeTe2 reaches the few-layers regime. However, this is highly challenging due to the need for a characterization technique that is local, highly sensitive, artifact-free, and operational with minimal fabrication. Prior studies have indicated that Curie temperature T
C can reach up to close to room temperature for exfoliated Fe5GeTe2 flakes, as measured via electrical transport; there is a need to validate these results with a measurement that reveals magnetism more directly. In this work, we investigate the magnetic properties of exfoliated thin flakes of vdW magnet Fe5GeTe2 via quantum magnetic imaging technique based on nitrogen vacancy centers in diamond. Through imaging the stray fields, we confirm room-temperature magnetic order in Fe5GeTe2 thin flakes with thickness down to 7 units cell. The stray field patterns and their response to magnetizing fields with different polarities is consistent with previously reported perpendicular easy-axis anisotropy. Furthermore, we perform imaging at different temperatures and determine the Curie temperature of the flakes at ≈300 K. These results provide the basis for realizing a room-temperature monolayer ferromagnet with Fe5GeTe2. This work also demonstrates that the imaging technique enables rapid screening of multiple flakes simultaneously as well as time-resolved imaging for monitoring time-dependent magnetic behaviors, thereby paving the way towards high throughput characterization of potential two-dimensional (2D) magnets near room temperature and providing critical insights into the evolution of domain behaviors in 2D magnets due to degradation.
Controlled growth mechanism of ring-like In(Ga)As quantum Dot pairs on GaAs ring-ring-disk nanostructures templates
Authors: Lang Qi-Zhi , Zhou Xun , Guo Xiang , Ding Zhao , Ye Yuan-Nong , Cao Yu
Published: February 2022

The ring-like In(Ga)As quantum dot pairs (QDPs) is prepared on GaAs ring-ring-disk (R-R-D) nanostructures template by droplet epitaxy (DE) method. The surface morphology of GaAs samples are characterized with Scanning Tunneling Microscope (STM), and studying local controlled growth mechanism of quantum dots (QDs) on GaAs R-R-D nanostructures. STM images show that In(Ga)As QDPs self-assembled a kind of complicated structure with one quantum dot (QD) pair in the center of nanostructures, other QDPs appearing both double rings and disk areas of original GaAs R-R-D nanostructures distributed like a exquisite ring. These In(Ga)As QDPs are uniformly arranged along the [1

1
¯

0] direction of GaAs(001) surface. Combining Stranski-Krastanov (S-K) growth mode and the tensile effect of strain field in the [1

1
¯

0] direction on sample surface, the nucleation position and distribution shape of ring-like In(Ga)As QDPs is locally controllable. It is found that high uniformly QDPs can be locally controlled by the original GaAs R-R-D nanostructures templates. These results can provide certain guiding significance for the controllable growth of QD by DE method.
Design of all-inorganic hole-transport-material-free CsPbI3/CsSnI3 heterojunction solar cells by device simulation
Authors: Xu Xingyu , Wang Jianfeng , Cao Dan , Zhou Yun , Jiao Zhiwei
Published: February 2022

The hole transport material (HTM)-free perovskite solar cells (PSCs) have attracted widespread interest due to enhanced stability and lowered cost as compared to the sandwich-type PSCs with an organic hole conductor. For the absorber layer, CsPbI3 has become a competitive candidate for its good chemical-components stability, excellent optoelectronic properties and most proper bandgap among inorganic halide perovskites. However, the power conversion efficiency of CsPbI3-based HTM-free PSCs is still much inferior to that of conventional ones. In this work, an all-inorganic-perovskite-heterojunction CsPbI3/CsSnI3 is proposed as the absorber and the HTM-free CsPbI3/CsSnI3 PSCs are investigated systematically through numerical simulation by using SCAPS-1D. Compared with the HTM-free PSCs employing a single CsPbI3 absorbing layer, the HTM-free CsPbI3/CsSnI3 PSCs have the extended absorption range and enhanced performance. The best cell efficiency is increased from 15.60% to 19.99% and from 13.87% to 19.59% for the cell with a back-front Au electrode and a back-front C electrode, respectively. It reveals that for the HTM-free CsPbI3/CsSnI3 heterojunction cells, C is a good choice for back-front electrode as it can achieve desirable cell performance with improved stability and lowered fabrication cost. These results indicate that the proposed HTM-free CsPbI3/CsSnI3 heterojunction cells are promising for photovoltaic applications.
Coherence pathway analysis of J-coupled lipids and lactate and effective suppression of lipids upon the selective multiple quantum coherence lactate editing sequence
Authors: Lee Seung-Cheol , Hariharan Hari , Arias-Mendoza Fernando , Mizsei Gabor , Nath Kavindra , Chawla Sanjeev , Elliott Mark A , Reddy Ravinder , Glickson Jerry D
Published: February 2022

Objective. The selective multiple quantum coherence (Sel-MQC) sequence is a magnetic resonance spectroscopy (MRS) technique used to detect lactate and suppress co-resonant lipid signals in vivo. The coherence pathways of J-coupled lipids upon the sequence, however, have not been studied, hindering a logical design of the sequence to fully attenuate lipid signals. The objective of this study is to elucidate the coherence pathways of J-coupled lipids upon the Sel-MQC sequence and find a strategy to effectively suppress lipid signals from these pathways while keeping the lactate signal. Approach. The product operator formalism was used to express the evolutions of the J-coupled spins of lipids and lactate. The transformations of the product operators by the spectrally selective pulses of the sequence were calculated by using the off-resonance rotation matrices. The coherence pathways and the conversion rates of the individual pathways were derived from them. Experiments were performed on phantoms and two human subjects at 3 T. Main results. The coherence pathways contributing to the various lipid resonance signals by the Sel-MQC sequence depending on the gradient ratios and RF pulse lengths were identified. Theoretical calculations of the signals from the determined coherence pathways and signal attenuations by gradients matched the experimental data very well. Lipid signals from fatty tissues of the subjects were successfully suppressed to the noise level by using the gradient ratio −0.8:−1:2 or 1:0.8:2. The new gradient ratios kept the lactate signal the same as with the previously used gradient ratio 0:−1:2. Significance. The study has elucidated the coherence pathways of J-coupled lipids upon the Sel-MQC sequence and demonstrated how lipid signals can be effectively suppressed while keeping lactate signals by using information from the coherence pathway analysis. The findings enable applying the Sel-MQC sequence to lactate detection in an environment of high concentrations of lipids.
Interactions between proposed energy-mix scenarios and non-energy Sustainable Development Goals (SDGs): a Sub-Sahara African perspective
Authors: Oghenekaro Ruseh Elohor , Kant Shashi
Published: February 2022

Sub- Sahara Africa (SSA) has the lowest access to energy globally which is partly responsible for its dismal socio-economic indices. The continent, however, has the unique opportunity to fuel its sustainable development using clean and sustainable energy. Given the continent’s aspirations, as well as its position and peculiarities within the context of the Sustainable Development Goals (SDGs) such as its hosting up to 90% of the world’s poorest countries, and generally lagging behind in development as most countries in Africa are not on track to meet the SDGs with the exception of the SDG on climate action, an assessment of the interactions and implications between the goal to provide access to clean, reliable, affordable, sustainable, and modern energy (SDG 7) and the other non-energy related SDGs is important for coherent cross-sectoral sustainable development planning and decision-making. This paper analyzes the interactions between SDG 7 and selected non-energy SDGs for three energy-mix scenarios—the current (2018), 2040 energy mix scenario proposed by International Energy Agency (IEA), and 2065 energy mix scenario proposed by Joint Research Centre (JRC) of the European Commission. The analyses are done for two countries - Nigeria and Ethiopia—that capture the wide variation in economic growth and energy sources across SSA. The analyses were carried out by adapting a seven-point scoring typology proposed by Nilsson et al (2016). The results indicate that in the case of Nigeria, the interactions between SDG 7 and many non-energy SDGs, such as SDGs 2, 6, and 13, become negative for the IEA 2040 scenario while they were positive for 2018 scenario. For the same two scenarios (IEA 2040 and the current), for Ethiopia, there are some negative influences on selected non-energy SDGs, but the direction of overall interactions does not change from positive to negative. In the case of JRC 2065 scenario, there are marginal negative influences on some non-energy SDGs, but neither in Nigeria nor in Ethiopia, there is no complete reverse change from positive to negative for any non-energy SDGs. Hence, JRC 2065 scenario is preferred. The study concludes with recommendations for policy interventions that would prevent the change of the interactions that move from positive in the 2018 scenario towards negative in the 2065 scenario (such as those that protect the rights of local communities to natural resources), as well as policies that may reduce the influence of negative interactions seen in both scenarios (such as reduction of air pollution).
MARMOT: magnetism, anisotropy, and more, using the relativistic disordered local moment picture at finite temperature
Authors: Patrick Christopher E , Staunton Julie B
Published: February 2022

We present MARMOT, a hybrid Python/FORTRAN implementation of the disordered local moment picture within multiple scattering density-functional theory. MARMOT takes atom-centred, scalar-relativistic potentials and constructs an effective medium (within the coherent potential approximation) to describe the disordered magnetic moment orientations at finite temperature. By solving the single-site scattering problem fully relativistically, spin–orbit effects are included, allowing the magnetocrystalline anisotropy to be calculated. Magnetic transition temperatures, spin and orbital moments, the density-of-states, and analytical parameterizations of the magnetic potential energy surface can also be calculated. Here, we describe the theory and practical implementation of MARMOT, and demonstrate its use by calculating Curie temperatures, magnetizations and anisotropies of bcc Fe, GdFe2 and YCo5.