bluuebunny/crossref_metadata_2025 huggingface dataset:
N-Phenylputrescine (NPP): a natural product inspired amine donor for biocatalysis
Authors: McKenna Catherine A. , Štiblariková Mária , De Silvestro Irene , Campopiano Dominic J. , Lawrence Andrew L.
Published: November 2021

A novel amine donor has been shown to be suitable for the transaminase-catalysed conversion of aldehydes and ketones to various amines across a range of conditions.
Natural eutectic solvents for sustainable recycling of poly(ethyleneterephthalate): closing the circle
Authors: Pestana Samuel C. , Machado João N. , Pinto R. Domingos , Ribeiro Bernardo D. , Marrucho Isabel M.
Published: November 2021

Aiming at providing a new solution for processing and recycling PET, the full solubilization of PET from water bottles in natural eutectic solvents was achieved as well as its full recovery, retaining PET properties and recycling the eutectic solvent.
Transesterification of rapeseed oil and waste corn oil toward the production of biodiesel over a basic high surface area magnetic nanocatalyst: application of the response surface methodology in process optimization
Authors: Tamoradi Taibeh , Kiasat Ali Reza , Veisi Hojat , Nobakht Valiollah , Karmakar Bikash
Published: November 2021

A new, green, and recoverable catalyst is prepared for the synthesis of biodiesel.
An all-lignin-based flexible supercapacitor based on a nitrogen-doped carbon dot functionalized graphene hydrogel
Authors: Cui Linlin , An Yingrui , Xu Hanping , Jia Mengying , Li Yue , Jin Xiaojuan
Published: November 2021

In this manuscript, the synthesis of a nitrogen-doped carbon dot functionalized graphene hydrogel and its application as a supercapacitor electrode have been reported.
Phenazine-based spiroborate complex with enhanced electrochemical stability for lithium storage
Authors: Hua Ying , Huang Yuanzhu , Wang Yujie , Du Ya , Yang Haishen
Published: November 2021

Novel lithium bis(2,3-dihydroxyphenazine)borate (LDPB) displays excellent electrochemical performance and was produced using a spiroboration salification strategy, which has been proven to be an effective way to develop novel electrode materials.
Simple fabrication and unprecedented visible light response of NiNb2O6/RGO heterojunctions for the degradation of emerging pollutants in water
Authors: Jones Benjamin Moses Filip , Mamba G. , Ansari Sajid Ali , Maruthamani D. , Muthuraj V. , Nkambule T. T. I.
Published: November 2021

Utilization of environmentally friendly and effective synthesis methods to fabricate visible light responsive photocatalysts with impressive catalytic performance is desirable in photocatalytic water treatment.
Highly branched polymethacrylates prepared efficiently: brancher-directed topology and application performance
Authors: Ma Yang , Yang Hong-Mei , Chen Zhi-Hao , Li Ya-Ning , Li Jun-Fang , Sun Xiu-Li , Wang Xiao-Yan , Tang Yong
Published: November 2021

A series of highly oil-soluble and branched polymethacrylates are prepared via ATRcP of 2-ethylhexyl methacrylate and divinyl brancher with high efficiency, focusing on the brancher effect on the structure-performance of the polymers.
Micro flow injection analysis of leucomalachite green in fish muscle using modified henequen fibers as microfluidic channels
Authors: Ferreira T. Alexandra , Guevara-Lara Alfredo , Paez-Hernandez M. Elena , Mondragon Alicia C. , Rodriguez Jose A.
Published: November 2021

In this work a simple and novel procedure for leucomalachite green determination based on micro flow injection analysis (μFIA) with amperometric detection is presented.
Facile and large-scale synthesis of polymorphic graphdiyne catalyzed by transition metal salts for organic pollutant removal
Authors: Zhu Jianhui , Liu Desheng , Li Changsheng , Zhang Bingjie , Wang Jianli , Wu Wenjuan , Ji Jiawen , Ma Yongqiang
Published: November 2021

Polymorphic GDYs were massively synthesized by transition metal salts, among which, CuSO4-catalyzed GDY can efficiently remove organic pollutants from water.
New facets of nanozyme activity of ceria: lipo- and phospholipoperoxidase-like behaviour of CeO2 nanoparticles
Authors: Sozarukova Madina M. , Proskurnina Elena V. , Popov Anton L. , Kalinkin Alexander L. , Ivanov Vladimir K.
Published: November 2021

CeO2 nanoparticles were shown to possess two novel types of enzyme-like activity, namely lipoperoxidase and phospholipoperoxidase activity.
Oxygen vacancies generated by Sn-doped ZrO2 promoting the synthesis of dimethyl carbonate from methanol and CO2
Authors: Song Shixian , Wei Jinyi , He Xuan , Yan Guangfu , Jiao Mengyan , Zeng Wei , Dai Fangfang , Shi Midong
Published: November 2021

Oxygen vacancy sites on a catalyst surface have been extensively studied and been proved to promote the adsorption and activation of carbon dioxide.
Highly efficient carbazolylgold(iii) dendrimers based on thermally activated delayed fluorescence and their application in solution-processed organic light-emitting devices
Authors: Li Lok-Kwan , Kwok Wing-Kei , Tang Man-Chung , Cheung Wai-Lung , Lai Shiu-Lun , Ng Maggie , Chan Mei-Yee , Yam Vivian Wing-Wah
Published: November 2021

A new class of carbazolylgold(iii) C^C^N dendrimers with thermally activated delayed fluorescence properties has been designed and synthesized for the realzaqtion of operationally stable solution-processed organic light-emitting devices.
Deciphering second harmonic generation signals
Authors: Foucaud Yann , Siboulet Bertrand , Duvail Magali , Jonchere Alban , Diat Olivier , Vuilleumier Rodolphe , Dufrêche Jean-François
Published: November 2021

Second harmonic generation is one of the most powerful techniques used to selectively probe interfaces of all types. The direct ab initio method developed here allows predicting the signal and highlights the importance of local and non-local effects.
Coupling Turing stripes to active flows
Authors: Bhattacharyya Saraswat , Yeomans Julia M.
Published: November 2021

We numerically solve the active nematohydrodynamic equations of motion, coupled to a Turing reaction–diffusion model, to study the effect of active nematic flow on the stripe patterns resulting from a Turing instability.
Multiscale simulations of polyzwitterions in aqueous bulk solutions and brush array configurations
Authors: Sgouros Aristotelis P. , Knippenberg Stefan , Guillaume Maxime , Theodorou Doros N.
Published: November 2021

Short- and long-range conformations of poly-zwitterions in aqueous solutions, and investigation of the antifouling properties of brush-array configurations in terms of the potential of mean force.
Mechanochemical synthesis of sodium carboxylates as anode materials in sodium ion batteries
Authors: Rainer Daniel N. , Desai Aamod V. , Armstrong A. Robert , Morris Russell E.
Published: November 2021

We present fast and sustainable mechanochemical synthesis of sodium carboxylates, usable as active material in sodium ion batteries with competitive electrochemical performance.
Revealing the role of solvent additives in morphology and energy loss in benzodifuran polymer-based non-fullerene organic solar cells
Authors: Zheng Zhi , He Enfang , Wang Jie , Qin Zhaotong , Niu Tianqi , Guo Fengyun , Gao Shiyong , Ma Zaifei , Zhao Liancheng , Lu Xinhui , Xue Qifan , Cao Yong , Mola Genene Tessema , Zhang Yong
Published: November 2021

Solvent additive (SA) treatment is the most effective strategy to obtain highly efficient non-fullerene organic solar cells (NF-OSCs).
Molecularly-imprinted hydrogel beads via self-sacrificing micro-reactors as safe and selective bilirubin adsorbents
Authors: Yin Shiqi , Xu Yinghui , Wang Zhoujun , Wei Zhiwei , Xu Tao , Zhao Weifeng , Zhao Changsheng
Published: November 2021

Brand new PAA–SS–rGO@BIL hydrogel beads as safe and self-anticoagulant BIL absorbents in the field of hemoperfusion.
The prospects of organic semiconductor single crystals for spintronic applications
Authors: Ding Mingyi , Gu Xianrong , Guo Lidan , Zhang Rui , Zhu Xiangwei , Li Rongjin , Zhang Xiaotao , Hu Wenping , Sun Xiangnan
Published: November 2021

Spintronic applications of OSSCs are discussed from the aspects of molecular structure, stacking structure, OSSC-based spintronic device fabrication, and multifunctional applications.
Mycolactone enhances the Ca2+ leak from endoplasmic reticulum by trapping Sec61 translocons in a Ca2+ permeable state
Authors: Bhadra Pratiti , Dos Santos Scott , Gamayun Igor , Pick Tillman , Neumann Clarissa , Ogbechi Joy , Hall Belinda S. , Zimmermann Richard , Helms Volkhard , Simmonds Rachel E. , Cavalié Adolfo
Published: November 2021

The Mycobacterium ulcerans exotoxin, mycolactone, is an inhibitor of co-translational translocation via the Sec61 complex. Mycolactone has previously been shown to bind to, and alter the structure of the major translocon subunit Sec61α, and change its interaction with ribosome nascent chain complexes. In addition to its function in protein translocation into the ER, Sec61 also plays a key role in cellular Ca2+ homeostasis, acting as a leak channel between the endoplasmic reticulum (ER) and cytosol. Here, we have analysed the effect of mycolactone on cytosolic and ER Ca2+ levels using compartment-specific sensors. We also used molecular docking analysis to explore potential interaction sites for mycolactone on translocons in various states. These results show that mycolactone enhances the leak of Ca2+ ions via the Sec61 translocon, resulting in a slow but substantial depletion of ER Ca2+. This leak was dependent on mycolactone binding to Sec61α because resistance mutations in this protein completely ablated the increase. Molecular docking supports the existence of a mycolactone-binding transient inhibited state preceding translocation and suggests mycolactone may also bind Sec61α in its idle state. We propose that delayed ribosomal release after translation termination and/or translocon ‘breathing' during rapid transitions between the idle and intermediate-inhibited states allow for transient Ca2+ leak, and mycolactone's stabilisation of the latter underpins the phenotype observed.
Close binary evolution based on Gaia DR2
Authors: Peng Weiguo , Song Hanfeng , Meynet Georges , Maeder Andre , Barblan Fabio , Zhang Ruiyu , Ekströmt Sylvia , Georgy Cyril , Long Gang , Zhao Liuyan , Qin Ying
Published: November 2021

Context. The observed late-type WC Wolf-Rayet stars (WC7-9) with low luminosity below log L/L⊙ < 5.4 in the HR diagram cannot be reproduced satisfactorily by the evolutionary track of single stars. The mass transfer due to Roche lobe overflow drastically modifies the internal structure and surface compositions of two components. Therefore, binaries provide a very promising evolutionary channel to produce these WC stars.

Aims. The Gaia satellite provides accurate distances to WC stars and confirms the luminosities of WC stars. Based on a small grid containing single stars and binaries, we aim to investigate the extent to which the evolution of a single or a close binary can reproduce the properties of these stars.

Methods. We considered single-star models with masses between 20 and 40 M⊙. We calculated the evolution for three binaries with a 30 M⊙ primary star with a 27 M⊙ companion star with initial orbital periods of 6.0, 20.0, 500.0, and 1000.0 days.

Results. The rotating single star can evolve into a late-type WC star but with high luminosity (i.e., log L/L⊙ > 5.4). Enhanced wind mass loss rates during RSG and WR stages, as proposed in the literature, can cause the star to approach the observational range of low-luminosity WC stars and favor the formation of low-luminosity WO stars. In a wide binary system with initial Porb = 1000 days, the primary star can evolve into a late-type WC star and be compatible with the observed properties of the low-luminosity WC stars. The result is almost insensitive to the adopted accretion efficiency 1 − β.

Conclusions. Compared with single stars, the low brightness is due to a smaller temperature gradient inside the star after the Case C Roche lobe overflow, while the low effective temperature is due to envelope expansion. There are four physical reasons for the formation of the expanding envelope. Firstly, less helium envelope can be transferred to the companion star in this system. Heavy helium envelopes can be heated by the helium burning shell and this creates the necessary conditions for the envelope expansion. Secondly, the expansion of the helium envelope can also be boosted by the sharp shrinkage of the larger carbon-oxygen core through the mirror effect. Thirdly, a more massive WC star can attain a higher Eddington factor because of its higher L/M ratio. The increase in L/M with mass is the primary cause for the extended envelopes in WC stars. Finally, the iron opacity bump at T ∼ 105.25 K may also trigger envelope inflation because it can lead to a larger Eddington factor.
CBD bei Hunden und Katzen
Authors: Marginter Ulrike
Published: November 2021

Cannabidiol (CBD) erfährt aktuell einen regelrechten Boom, auch für unsere Vierbeiner. Doch ist dieser Boom überhaupt gerechtfertigt? Was kann es wirklich? Was muss man bei der Verabreichung beachten? Und wie kann man die Qualität der unterschiedlichen Produkte einschätzen?
Cationic Iridium/Chiral Bidentate Phosphoramidite Catalyzed Asymmetric Hydroarylation
Authors: Yamamoto Yasunori , Shirai Tomohiko
Published: November 2021

In this personal account, we summarize our investigations on the asymmetric direct addition of C(sp2)–H bonds to unsaturated bonds, such as C=O and C=C, using cationic iridium/chiral O-linked bidentate phosphoramidite (Me-BIPAM) and S-linked bidentate phosphoramidite (S-Me-BIPAM) catalyst systems.

1 Introduction

2 Highly Enantioselective Intramolecular Hydroarylation of α-Keto Amides

3 Highly Enantioselective Intermolecular Hydroarylation of Bicyclo­alkenes

4 Conclusion
Vacuum-Assisted Excision, Scarless Solution for Fibroadenoma Breast—A Single-Center Experience
Authors: Rupa R. , Kushvaha Suchana
Published: November 2021

Background Fibroadenoma is one of the most common benign breast lesions that is frequently surgically excised in breast practice.

Aim The aim of this study was to determine the efficacy and safety of ultrasound-guided (USG) vacuum-assisted excision biopsy (VAEB) of fibroadenoma.

Settings and Design A retrospective observational study.

Methods and Materials A total of 113 patients with 163 fibroadenomas who underwent USG-guided VAEB under local anesthesia with 7G and 10G probes using an Encor Enspire equipment were included in the study. The patients were followed up after 1, 6, and 12 months. The fibroadenomas up to 4 cm were excised as per the U.S. Food and Drug Administration-approved guidelines of the American Society of Surgeons for percutaneous removal of benign breast lesions.

Results The percentage of complete excision rate was 98.8% and the most frequent complication encountered was hematoma including immediate and delayed accounting for 3.06%. There were no recurrent lesions in our study.

Conclusion USG-guided VAEB of benign breast lumps can be a safe and effective alternative to surgical excision and had better patient satisfaction in terms of efficacy and cosmesis.
Tumors of the Acromion Process—A Pictorial Review
Authors: Boo S.L. , Saad A. , Khan Z. , Davies A. M. , James S. L. , Botchu R.
Published: November 2021

Introduction Acromion is essential for stabilizing the shoulder complex. Tumors of the acromion are rare. We report the largest series of acromion tumor and tumor-like lesion.

Materials and Methods A retrospective review of the oncology and radiology database within our tertiary center for orthopaedic oncology was performed to identify all tumors of the acromion over the past 30 years and imaging was reviewed.

Results We identified a total of 31 lesions arising in the acromion and chondrosarcoma was the commonest.

Conclusion One needs to be aware of tumor and tumor-like lesions of acromion.
Pyomyositis of the Piriformis Muscle—A Case of Piriformis Syndrome
Authors: Shanmuga Jayanthan S , Rajkumar S. Senthil , Kumar V. Senthil , Shalini M.
Published: November 2021

Piriformis syndrome is a rare cause of sciatica, which results in low backache due to sciatic nerve compression. This syndrome is associated with abnormalities in the piriformis muscle, which cause sciatic nerve entrapment, like anatomical variations, muscle hypertrophy, and inflammation. It can also result from the abnormal course of sciatic nerve itself through normal piriformis muscle. Piriformis syndrome due to pyomyositis of the piriformis muscle is extremely rare and only 23 cases are reported in literature. Herein, we report one such rare case of a patient, with pyomyositis of piriformis muscle, who presented with piriformis syndrome.
Aerodynamics of tiny wings show how small insects fly by wing acceleration
Authors: Johnson-Groh Mara
Published: November 2021

Drag forces produced by the bristled wings on small insects might help design future millimeter-scale flying aircraft.
Fingerprints of the cosmic ray driven mechanism of the ozone hole
Authors: Lu Qing-Bin
Published: November 2021

There is long research interest in electron-induced reactions of halogenated molecules. It has been two decades since the cosmic-ray (CR) driven electron-induced reaction (CRE) mechanism for the ozone hole formation was proposed. The derived CRE equation with the stratospheric equivalent chlorine level and CR intensity as the only two variables has well reproduced the observed data of stratospheric O3 and temperatures over the past 40 years. The CRE predictions of 11-year cyclic variations of the Antarctic O3 hole and associated stratospheric cooling have also been well confirmed. Measured altitude profiles of the ozone and temperatures in Antarctic ozone holes provide convincing fingerprints of the CRE mechanism. A quantitative estimate indicates that the CRE-produced Cl atoms could completely deplete or even overkill the ozone in the CR-peak polar stratospheric region, consistent with the observed altitude profiles of the severest Antarctic ozone holes. After removing the natural CR effect, the hidden recovery in the Antarctic O3 hole since ∼1995 is clearly discovered, while the recovery of O3 loss at mid-latitudes is being delayed by ≥10 years. These results have provided strong evidence of the CRE mechanism. If the CR intensity keeps the current rising trend, the Antarctic O3 hole will return to the 1980 level by ∼2060, while the returning of the O3 layer at mid-latitudes to the 1980 level will largely be delayed or will not even occur by the end of this century. The results strongly indicate that the CRE mechanism must be considered as a key factor in evaluating the O3 hole.
Integrated atomic force microscopy and x-ray irradiation for in situ characterization of radiation-induced processes
Authors: Riechers Shawn L. , Petrik Nikolai , Loring John S. , Murphy Mark K. , Pearce Carolyn I. , Kimmel Greg A. , Rosso Kevin M.
Published: November 2021

Understanding radiation-induced chemical and physical transformations at material interfaces is important across diverse fields, but experimental approaches are often limited to either ex situ observations or in situ electron microscopy or synchrotron-based methods, in which cases the radiation type and dose are inextricably tied to the imaging basis itself. In this work, we overcome this limitation by demonstrating integration of an x-ray source with an atomic force microscope to directly monitor radiolytically driven interfacial chemistry at the nanoscale. We illustrate the value of in situ observations by examining effects of radiolysis on material adhesion forces in aqueous solution as well as examining the production of alkali nitrates at the interface between an alkali halide crystal surface and air. For the examined salt–air interface, direct visualization under flexible experimental conditions greatly extends prior observations by enabling the transformation process to be followed comprehensively from source-to-sink with mass balance quantitation. Our novel rad-atomic force microscope opens doors into understanding the dynamics of radiolytically driven mass transfer and surface alteration at the nanoscale in real-time.
The CoPhyLab comet-simulation chamber
Authors: Kreuzig C. , Kargl G. , Pommerol A. , Knollenberg J. , Lethuillier A. , Molinski N. S. , Gilke T. , Bischoff D. , Feller C. , Kührt E. , Sierks H. , Hänni N. , Capelo H. , Güttler C. , Haack D. , Otto K. , Kaufmann E. , Schweighart M. , Macher W. , Tiefenbacher P. , Gundlach B. , Blum J.
Published: November 2021

The Comet Physics Laboratory (CoPhyLab) is an international research program to study the physical properties of cometary analog materials under simulated space conditions. The project is dedicated to studying, with the help of multiple instruments and the different expertise and background from the different partners, the physics of comets, including the processes inside cometary nuclei, the activity leading to the ejection of dust and gas, and the sub-surface and surface evolution of cometary nuclei when exposed to solar illumination. CoPhyLab will provide essential information on the formation and evolution of comets and insights into the origins of primitive Solar System bodies. To this end, we constructed a new laboratory that hosts several small-scale experiments and a large-scale comet-simulation chamber (L-Chamber). This chamber has been designed and constructed to host ice–dust samples with a diameter of up to 250 mm and a variable height between 100 and 300 mm. The cometary-analog samples will be kept at temperatures below 120 K and pressures around 10−6 mbar to ensure cometary-like conditions. In total, 14 different scientific instruments are attached to the L-Chamber to study the temporal evolution of the physical properties of the sample under different insolation conditions. Due to the implementation of a scale inside the L-Chamber that can measure weight changes of the samples with high precision, the cooling system is mechanically decoupled from the sample holder and cooling of the samples occurs by radiation only. The constructed chamber allows us to conduct uninterrupted experiments at low temperatures and pressures up to several weeks.
All-carbon approach to inducing electrical and optical anisotropy in graphene
Authors: Antidormi Aleandro , Cummings Aron W.
Published: November 2021

Owing to its array of unique properties, graphene is a promising material for a wide variety of applications. Being two-dimensional, the properties of graphene are also easily tuned via proximity to other materials. In this work, we investigate the possibility of inducing electrical and optical anisotropy in graphene by interfacing it with other anisotropic carbon systems, including nanoporous graphene and arrays of graphene nanoribbons. We find that such materials do indeed induce such anisotropy in graphene while also preserving the unique properties offered by graphene’s Dirac band structure, namely, its superior charge transport and long-wavelength optical absorption. The optical anisotropy makes such heterostructures interesting for their use in applications related to long-wavelength polarimetry, while the electrical anisotropy may be valuable for enhancing the performance of graphene photothermoelectric detectors.
Effect of recirculation zones on the ventilation of a public washroom
Authors: Sinha Krishnendu , Yadav Mani Shankar , Verma Utkarsh , Murallidharan Janani Srree , Kumar Vivek
Published: November 2021

Air-borne transmission can pose a major risk of infection spread in enclosed spaces. Venting the air out using exhaust fans and ducts is a common approach to mitigate the risk. In this work, we study the air flow set up by an exhaust fan in a typical shared washroom that can be a potential hot spot for COVID-19 transmission. The primary focus is on the regions of recirculating flow that can harbor infectious aerosol for much longer than the well-ventilated parts of the room. Computational fluid dynamics is used to obtain the steady state air flow field, and Lagrangian tracking of particles gives the spatial and temporal distribution of infectious aerosol in the domain. It is found that the washbasin located next to the door is in a prominent recirculation zone, and particles injected in this region take much longer to be evacuated. The ventilation rate is found to be governed by the air residence time in the recirculation zone, and it is much higher than the timescale based on fully mixed reactor model of the room. Increasing the fan flow rate can reduce the ventilation time, but cannot eliminate the recirculation zones in the washroom.
Optimal strategies for a cost-effective and reliable 100% renewable electric grid
Authors: Houssainy Sammy , Livingood William
Published: November 2021

This paper explores cost-optimal pathways to 100% renewable power systems for the U.S. building stock. We show that long-duration misalignments of supply and demand, spanning from multi-day to seasonal timescales, present a dominant challenge that must be addressed to meet real-time 100% renewable targets. While long-duration misalignments can be addressed through energy storage, we show that alternative and readily available solutions that are more cost-effective should be considered first. Through a techno-economic analysis, we identify cost-optimal, region-dependent, supply-side, and demand-side strategies that reduce, and in some U.S. regions eliminate, the otherwise substantial capacities and associated costs of long-duration energy storage. Investigated supply-side strategies include optimal mixes of renewable portfolios and oversized generation capacities. Considered demand-side strategies include building load flexibility and building energy efficiency investments. Our results reveal that building energy efficiency measures can reduce long-duration storage requirements at minimum total investment costs. In addition, oversizing and diversifying renewable generation can play a critical role in reducing storage requirements, remaining cost effective even when accounting for curtailed generation. We identify regionally dependent storage cost targets and show that for emerging long-duration energy storage innovations to achieve broad adoption, their costs will need to compete with the decreasing cost of renewables. The findings of this research are particularly important given that most long-duration storage technologies are currently either uneconomical, geologically constrained, or still underdeveloped.
Impact of temperature-dependent series resistance on the operation of AlGaN/GaN high electron mobility transistors
Authors: Jeon Dae-Young , Koh Yumin , Cho Chu-Young , Park Kyung-Ho
Published: November 2021

AlGaN/GaN high electron mobility transistors (HEMTs) possess excellent electrical and thermal properties. In this study, we examined the electrical performance of AlGaN/GaN HEMTs to clarify the operational mechanism of the device with temperature variation in an effort to further advance development of high-speed, high-power devices and sensors for temperature applications. Our results revealed drain current degradation caused by temperature-dependent series resistance, as well as several scattering mechanisms. In addition, a negligible surface roughness scattering effect in AlGaN/GaN HEMTs was confirmed through mobility attenuation factors.
Bragg scattering of long flexural gravity waves by an array of submerged trenches and the analysis of blocking dynamics
Authors: Barman S. C. , Boral S. , Sahoo T. , Meylan Michael H.
Published: November 2021

Bragg scattering of long flexural gravity waves due to an array of submerged trenches is studied under the shallow water approximation and small amplitude structural response in the presence of lateral compressive force. The group velocity vanishes at two different points in the frequency space for specific values of the compressive force, which are referred to as primary and secondary blocking points. Between these two blocking points, three propagating modes exist for each frequency, of which two are associated with the positive group velocity and one with the negative group velocity. Of the three propagating wave modes, the contribution to the energy relation by the lowest wavenumber is predominant near the secondary blocking frequency. In contrast, the higher wavenumber is dominant in the proximity of the primary blocking frequency. The study reveals the occurrence of Bragg scattering of flexural gravity waves in the presence of compressive force for more than two submerged trenches, which is analogous to that of surface gravity waves. However, within the blocking limits of the compressive force, the superposition of multiple propagating wave modes and the change in the incident wave mode contribute to certain irregularities and an increase in wave amplitude in the Bragg reflection pattern. The response amplitude of the structure and the pulse rate increase with an increase in the number of trenches.
Catalytic production of diesel-like oils from plastic wastes
Authors: Arnold Michael , Boghosian Baron , Li Mingheng
Published: November 2021

A dewaxing catalyst was prepared through the dissolution of nickel oxide and tungsten powders in an aqueous medium, followed by impregnation of a Zeolite Socony Mobil-5 substrate and calcination at 500 °C. The synthesized catalyst was used in conjunction with a lab-designed, single-stage pyrolytic reactor running at a set point of 360 °C to break down a mixture of plastic grocery bags. The catalyst was found to be selective to the C9–C22 isomers typical of diesel No. 2. Gas chromatographic analysis indicated that the fraction of C24 and heavier components in the pyrolysis product was only 1.0%. Implications for process scale-up and economics are discussed.
Demonstration of MHz frequency domain multiplexing readout of 37 transition edge sensors for high-resolution x-ray imaging spectrometers
Authors: Akamatsu H. , Vaccaro D. , Gottardi L. , van der Kuur J. , de Vries C. P. , Kiviranta M. , Ravensberg K. , D'Andrea M. , Taralli E. , de Wit M. , Bruijn M. P. , van der Hulst P. , den Hartog R. H. , van Leeuwen B.-J. , van der Linden A. J. , McCalden A. J. , Nagayoshi K. , Nieuwenhuizen A. C. T. , Ridder M. L. , Visser S. , van Winden P. , Gao J. R. , Hoogeveen R. W. M. , Jackson B. D. , den Herder J.-W. A.
Published: November 2021

We report on the development and demonstration of MHz frequency domain multiplexing (FDM) technology to readout arrays of cryogenic transition edge sensor (TES) x-ray microcalorimeters. In our FDM scheme, TESs are AC biased at different resonant frequencies in the low MHz range through an array of high-Q LC resonators. The current signals of all TESs are summed at superconducting quantum interference devices (SQUIDs). We have demonstrated multiplexing for a readout of 31 pixels using room temperature electronics, high-Q LC filters, and TES arrays developed at SRON, and SQUID arrays from VTT. We repeated this on a second setup with 37 pixels. The summed x-ray spectral resolutions @ 5.9 keV are ΔE31pix MUX=2.14 ± 0.03 eV and ΔE37pix MUX=2.23 ± 0.03 eV. The demonstrated results are comparable with other multiplexing approaches. There is potential to further improve the spectral resolution, to increase the number of multiplexed TESs, and to open up applications for TES x-ray microcalorimeters.
Electron–molecule collisions with explicit rovibrational resolution at MRCI level and using even tempered basis sets
Authors: Oliveira A. P. , Alencar Amanda , Jalbert Ginette , Rocha A. B.
Published: November 2021

A method for calculating the generalized oscillator strengths (GOSs) and differential cross section (DCS) with vibration and rotation resolution is presented. The importance of accounting for the rotational contribution is to be emphasized since it has not previously been considered in GOS calculations. Although largely neglected due to its small effect on various properties, the rotational resolution proved to be fundamental in the study of certain phenomena, such as the interference between rotational states in a molecule. As the general goal of this work is to obtain theoretical values comparable to high resolution experiments, special care was taken on the calculation of the electronic part of the scattering amplitude, particularly in what concerns the choice of the atomic basis set. Accordingly, even-tempered basis sets have proved to lead to good results. The helium atom was taken as a model system for this aspect of the problem. Then, GOS and DCS, for explicit vibrational and rotational transitions, were calculated for hydrogen and nitrogen molecules. For higher accuracy, a non-Franck–Condon approach was used to obtain transitions involving vibrational states. The resultant values have shown good agreement with the available experimental data.
A single spectroscopic probe for in situ analysis of electronic and vibrational information at both sides of electrode/electrolyte interfaces using surface-enhanced Raman scattering
Authors: Isogai Taichi , Motobayashi Kenta , Ikeda Katsuyoshi
Published: November 2021

Surface-enhanced Raman scattering (SERS) at electrode/electrolyte interfaces includes inelastic light scattering not only by molecular vibrations in the electrolyte phase but also by conduction electrons in the metal electrode phase. While the former, i.e., vibrational SERS (VSERS), is widely used to obtain chemical information on electrode surfaces, the latter, i.e., electronic SERS (ESERS), is still under discussion as a possible origin of the SERS background. Given that electronic Raman scattering is essentially sensitive to the surface charge density of a metal, we conducted a thorough comparison of electrochemical potential dependence of SERS signals in both acidic and alkaline media. Significant intensity changes in the SERS background were observed close to the respective potentials of zero charge in acidic and alkaline media, supporting the contention that the generation of the SERS background can be explained by the ESERS mechanism. Moreover, the ESERS intensities, as the SERS background, were reversibly varied by anion adsorption/desorption at the electrochemical interfaces in conjunction with VSERS features originated from surface-adsorbate vibrations. The sensitivity to the surface charge was much higher in this method than in the conventional combined method of reflectance and SERS. In situ monitoring of both chemical and electronic structures at electrode/electrolyte interfaces using a single spectroscopic probe can avoid various experimental uncertainties caused by combined application of different spectroscopic methods leading to facilitation of our deeper understanding of electrode processes.
Study of multi-mode forcing effects on coherent structures of flow transition in a compressible jet
Authors: Xu Cong , Lai Huanxin
Published: November 2021

The disturbances added to trigger turbulence in the simulation of jet flows are mostly implemented with multiple azimuthal modes. The validity and rationale of using such multi-modes are still not very clear. In this paper, large eddy simulations are performed to study a compressible isothermal jet. Flow forcing methods for promoting transition are considered. Two multi-mode disturbances and a single-mode excitation are shown to trigger rapid flow transition, but the development of mixing layers in downstream varies. The most organized vortical structures produced by the vortex rolling/pairing process are observed when the jet is excited by the single-mode forcing, while the shear layers are closer to turbulence when the two multi-mode disturbances are employed. In order to unveil the mechanism behind such differences, dynamic mode decompositions on the axial velocity are conducted to analyze the spatiotemporal coherent structures. The results show that near the nozzle exit, the multi-mode disturbances have triggered more high frequency coherent structures, while the single-mode forcing has produced both low and high frequencies. The low frequency components are transmitted downstream of the jet, leading to poor prediction of the turbulent flow properties.
Study on the bedding angle on the mechanical properties of shale
Authors: Zhang Shuhui
Published: November 2021

Conventional mechanical tests under static loading can prove that the angle of the shale bedding plane is the main reason for the anisotropy of its mechanical behavior. In order to explore the influence of the angle in the layer on the anisotropic mechanical behavior of shale, the uniaxial compression mechanical tests were carried out under the conditions of 0°, 15°, 30°, 45°, 60°, 75°, and 90°. The results show that (1) the anisotropy degree of shale compressive strength shows the “W” type with the increase in the bedding angle, while the anisotropy degree of elastic modulus and Poisson’s ratio shows the “V” type with the influence of the bedding angle, but the minimum value of elastic modulus is around 45° and the minimum value of Poisson’s ratio is around 30°; and (2) the analysis of variance has a significant effect on compressive strength, elastic modulus, and Poisson’s ratio. Generally speaking, the anisotropic mechanical characteristics of shale have a great influence with the change in the bedding angle. The research conclusion is helpful to understand the mechanical behavior of shale.
Focusing and spin polarization of atomic hydrogen beam
Authors: Nagaya Y. , Nakatsu H. , Ogura S. , Shimazaki K. , Ueta H. , Takeyasu K. , Fukutani K.
Published: November 2021

We have developed a spin-polarized-hydrogen beam with a hexapole magnet. By combining the beam chopper and pulsed laser ionization detection, the time-of-flight of the hydrogen beam was measured, and the dependence of the beam profile on the velocity was acquired, which was consistent with the beam trajectory simulations. The spin polarization of the beam was analyzed by using the Stern–Gerlach-type magnet in combination with the spatial scan of the detection laser. The spin polarization was about 95% at a focusing condition due to the hexapole magnet. The polarization was, on the other hand, reduced to about 70% for the beam at higher velocities, which is consistent with simulation results.
Exciton maps for thermally activated delayed fluorescence active/inactive carbazole benzonitrile derivatives
Authors: Noguchi Yoshifumi
Published: November 2021

The all-electron first-principles GW+Bethe–Salpeter method was applied to six carbazole benzonitrile (CzBN) derivatives, which were recently reported to be both thermally activated delayed fluorescence (TADF) active and inactive despite their singlet–triplet splittings being commonly around 0.2 eV. The present method successfully reproduced very similar photoabsorption spectra as experiments from the viewpoint of the peak positions and relative peak heights. We also performed exciton analysis with the exciton wave functions for several lowest singlet and triplet exciton states to reveal the details of the optical properties. We applied this to not only the present six CzBN derivatives but also 18 other TADF molecules and proposed a new exciton map to classify the molecules as the TADF active/inactive by using the exciton binding energy in the vertical axis and the ratio of electron and hole delocalization in the horizontal axis. Our results suggest two possible TADF mechanisms: spatially less localized hole states than the electron states where the exciton binding energy is proportional to the ratio of hole and electron delocalization and spatially more localized hole states than the electron states where the exciton binding energy should be large.
Strain hardening and shock mitigation response of polyurethane under high strain rates
Authors: Singh Amandeep , Shivling V. D. , Khosla P. K. , Saini Ashish , Kumar Vijay , Trigunayak Ankur
Published: November 2021

Polyurethane is a promising candidate for the potting of embedded electronics due to its shock absorbing properties. This paper discusses the less known strain hardening and shock mitigation properties of 4,4′-methylenediphenyl diisocyanate based polyurethane under dynamic loading. This study is reported in a strain rate range of 1600–2900 s−1 under compression using a split-Hopkinson pressure bar (SHPB). The experimental stress–strain behavior of polyurethane was modeled with Hollomon’s equation to analyze its hardening behavior in dynamic environments. Jointly, the incident, reflected, and transmitted strain signals of the SHPB are analyzed in time and frequency domains to understand the shock absorbing properties of polyurethane. Polyurethane was found to absorb more shock for more intense loading. It was observed to mitigate 81% of shock energy with frequencies up to 10 kHz.
Tunable microwave absorbing property of RGO/Fe3O4/SiO2 nanocomposites by effective regulation of eddy current effect
Authors: Zhang Yahong , Lv Xiaoyan , Zhang Yi , Jiang Zhiyang , Gong Chunhong
Published: November 2021

The ternary RGO/Fe3O4/SiO2 composites were prepared through a hydrothermal method and an annealing process. The Fe3O4 and SiO2 particles were in situ grown on the surface of reduced graphene oxide (RGO). The RGO, Fe3O4, and SiO2 were properly assembled to realize comprehensive electromagnetic wave-absorbing performance, which not only achieve synergy between the dielectric loss and the magnetic loss, but also possess satisfactory impedance matching. Based on the analysis of absorbing properties, the RGO/Fe3O4/SiO2-0.5 composite exhibits the optimal wave absorbing performance with the maximum reflection loss of −34.36 dB and an effective absorption bandwidth of 7.76 GHz at a matching thickness of 2.9 mm. The introduction of wave transparent and insulated SiO2 increases the propagation paths and optimizes the conductivity. Meanwhile, the construction of a heterogeneous interface promotes the interfacial polarization. The appropriate conductive network and the defect sites of RGO guarantee the conduction loss and dipole polarization. The natural resonance and exchange resonance from Fe3O4 jointly contribute to the magnetic loss. Therefore, this work provides a simple and flexible method for the synthesis and design of the heterostructure with multiple dissipation mechanism as a high-efficiency absorbent.
Realization of 366 nm GaN/AlGaN single quantum well ultraviolet laser diodes with a reduction of carrier loss in the waveguide layers
Authors: Yang J. , Wang B. B. , Zhao D. G. , Liu Z. S. , Liang F. , Chen P. , Zhang Y. H. , Zhang Z. Z.
Published: November 2021

The performance of ultraviolet (UV) laser diodes (LDs) with a low Al mole fraction AlGaN cladding layer was investigated by varying the thicknesses of the waveguide layer. It is found that (1) the loss of carriers in the waveguide layer is much larger than that in blue or green LDs due to the shallower quantum well and consequently a weaker carrier confinement of UV lasers. (2) Carrier loss in the waveguide layer can be suppressed by using a thinner waveguide layer. Therefore, the threshold current of LDs can be reduced. (3) The ultraviolet GaN/AlGaN single quantum well laser diodes lasing at 366 nm are fabricated by using relatively thin AlGaN waveguide layers and low Al mole fraction AlGaN cladding layers.
Multidimensional spectroscopy of magneto-excitons at high magnetic fields
Authors: Mapara V. , Stevens C. E. , Paul J. , Barua A. , Reno J. L. , McGill S. A. , Hilton D. J. , Karaiskaj D.
Published: November 2021

We perform two-dimensional Fourier transform spectroscopy on magneto-excitons in GaAs at magnetic fields and observe Zeeman splitting of the excitons. The Zeeman components are clearly resolved as separate peaks due to the two-dimensional nature of the spectra, leading to a more accurate measurement of the Zeeman splitting and the Landé g factors. Quantum coherent coupling between Zeeman components is observed using polarization dependent one-quantum two-dimensional spectroscopy. We use two-quantum two-dimensional spectroscopy to investigate higher four-particle correlations at high magnetic fields and reveal the role of the Zeeman splitting on the two-quantum transitions. The experimental two-dimensional spectra are simulated using the optical Bloch equations, where many-body effects are included phenomenologically.
The challenge of tuning the ratio of lattice/total thermal conductivity toward conversion efficiency vs power density
Authors: Song Shaowei , Xu Congcong , Liang Zhongxin , Ren Zhifeng
Published: November 2021

Minimizing the lattice thermal conductivity of thermoelectric materials is essential for preserving the temperature difference during the operation of thermoelectric devices incorporating these materials. During the past two decades, there has been substantial improvement in the thermoelectric figure of merit (zT) due to reduced lattice thermal conductivity. Employing alloying effects in solid-solution compounds is the most common and practical approach for inhibiting lattice thermal conductivity. This Perspective takes the n-type Mg3Sb2−xBix thermoelectric alloys as examples, addressing their lattice thermal conductivity and corresponding zT as functions of their Bi concentration. Additionally, we seek to understand the effect of the lattice contribution to total thermal conductivity for most thermoelectric materials currently being researched. The lattice/total thermal conductivity ratio at the temperature corresponding to the peak zT shows weak material dependence, widely ranging from 0.5 to 0.75, which implies that the lattice thermal conductivity of most thermoelectric materials can be decreased further to improve thermoelectric performance. On the other hand, thermoelectric materials with relatively low ratios exhibit high power factors in their operating temperature ranges, which is ascribed to their excellent electrical performance. These observations provide guidelines to tune transport properties for future applications in thermoelectric power generation.
X-ray-induced acoustic computed tomography (XACT) imaging with single-shot nanosecond x-ray
Authors: Wang Siqi , Ivanov Vassili , Pandey Prabodh Kumar , Xiang Liangzhong
Published: November 2021

X-ray-induced acoustic computed tomography (XACT) has emerged as a promising imaging modality with broad applications in both biomedicine and nondestructive testing. The previous XACT imaging systems require thousands of averages to achieve reasonable images. Here, we report the experimental demonstration of single-shot XACT imaging of a metal object using a single-shot 50 ns x-ray pulse. A two-stage dedicated amplification and a 128-channel parallel data acquisition configuration were introduced for XACT imaging to enable sufficient acoustic signal amplification and maintain an overall low noise level for single-shot XACT imaging. Details of the system design are presented; the improved signal-to-noise ratio (>23 dB) and image reconstruction have been demonstrated with a ring ultrasound transducer array imaging system. The study paves the way for realizing real-time XACT imaging and its potential applications in image-guided intervention.
Sequential doping of solid chunks of a conjugated polymer for body-heat-powered thermoelectric modules
Authors: Yu Liyang , Scheunemann Dorothea , Lund Anja , Kiefer David , Müller Christian
Published: November 2021

Sequential doping of 1 mm3 sized cubes of regio-regular poly(3-hexylthiophene) (P3HT) with 2,3,5,6-tetrafluoro-tetracyanoquinodimethane is found to result in a doping gradient. The dopant ingresses into the solid material and after two weeks of sequential doping yields a 250 μm thick doped surface layer, while the interior of the cubes remains undoped. The doping gradient is mapped with energy dispersive x-ray spectroscopy (EDX), which is used to estimate a diffusion coefficient of 1 × 10−10 cm2 s−1 at room temperature. The cubes, prepared by pressing at 150 °C, feature alignment of polymer chains along the flow direction, which yields an electrical conductivity of 2.2 S cm−1 in the same direction. A 4-leg thermoelectric module was fabricated with slabs of pressed and doped P3HT, which generated a power of 0.22 μW for a temperature gradient of 10.2 °C generated by body heat.