bluuebunny/crossref_metadata_2025 huggingface dataset:
Electrochemical reduction of nitrate on silver surface and an in situ Raman spectroscopy study
Authors: Lei Fengcai , Li Kun , Yang Maosen , Yu Jing , Xu Mengmeng , Zhang Yiming , Xie Junfeng , Hao Pin , Cui Guanwei , Tang Bo
Published: April 2022

Ag/ZnO hierarchical structure can efficiently catalyze nitrate reduction as well as a sensitive surface-enhanced Raman scattering (SERS)-active substrate to figure out the mechanism of the Ag-catalyzed electroreduction process.
Importance of favourable non-covalent contacts in the stereoselective synthesis of tetrasubstituted chromanones
Authors: Andreola Laura R. , Wheeler Steven E.
Published: April 2022

Automated transition state structure computations for a Pd-catalysed conjugated addition of arylboronic acids to 2-substituted chromones reveal unexpected conformations of the key stereodifferentiating benzyl group on the PyDHIQ ligand.
Tandem trifluoromethylthiolation and cyclization of N-aryl-3-butenamides with AgSCF3: divergent access to CF3S-substituted 3,4-dihydroquinolin-2-ones and azaspiro[4,5]dienones
Authors: Wang Liang , Xie Lin , Fang Zeguo , Zhang Qian , Li Dong
Published: April 2022

A AgSCF3-mediated tandem trifluoromethylthiolation and cyclization of N-aryl-3-butenamides was developed, which enabled the selective syntheses of CF3S-substituted 3,4-dihydroquinolin-2-ones and azaspiro[4,5]dienones.
Efficient preparation of unsymmetrical alkyl–aryl tellurides via a nickel-catalyzed reductive coupling strategy
Authors: Wang Fei , Chen Ying , Ackermann Lutz , Wang Shun-Yi
Published: April 2022

A selective cross-coupling between unactivated alkyl bromides and diaryl tellurides through reductive nickel-catalysis is described, which efficiently led to unsymmetrical alkyl–aryl tellurides.
Post-synthetic modification of graphene quantum dots bestows enhanced biosensing and antibiofilm ability: efficiency facet
Authors: Agrawal Neha , Bhagel Dolly , Mishra Priyanka , Prasad Dipti , Kohli Ekta
Published: April 2022

The present work highlights a novel post-synthetic modification route for graphene quantum dots, which was found to be efficient for both the biosensing of dopamine as well as Staphylococcus aureus biofilm degradation.
Exploring the similarity of single-layer covalent organic frameworks using electronic structure calculations
Authors: Raptakis Antonios , Croy Alexander , Dianat Arezoo , Gutierrez Rafael , Cuniberti Gianaurelio
Published: April 2022

Exploiting a similarity metric to classify COFs according to the degree of π-electron conjugation of their bridges.
Synthesis, characterisation, and feasibility studies on the use of vanadium tellurate(vi) as a cathode material for aqueous rechargeable Zn-ion batteries
Authors: Nagarathinam Mangayarkarasi , Soares Cindy , Chen Yue , Seymour Valerie R. , Mazanek Vlastimil , Isaacs Mark A. , Sofer Zdenek , Kolosov Oleg , Griffin John M. , Tapia-Ruiz Nuria
Published: April 2022

(NH4)4{(VO2)2[Te2O8(OH)2]}·2H2O is tested as a cathode in an aqueous Zn-ion battery for the first time, showing a discharge capacity of 283 mA h g−1 in half-cells and excellent capacity retention (91%) in concentration cells after 20 cycles.
Time-dependent multivariate and spectroscopic characterisation of oil residue in Niger Delta soil
Authors: Menkiti Nnamdi David , Isanbor Chukwuemeka , Ayejuyo Olusegun , Doamekpor Louis Korbla , Twum Emmanuel Osei
Published: April 2022

Weathering indices from spectroscopic characterisation and multivariate analysis of crude oil spill residue at different times of spill in the Niger Delta of Nigeria was used to develop a predictive model for assessment of compositional changes in oil residue after a spill.
Degradation mechanism of a lignin model compound during alkaline aerobic oxidation: formation of the vanillin precursor from the β-O-4 middle unit of softwood lignin
Authors: Hirano Yuki , Izawa Akari , Hosoya Takashi , Miyafuji Hisashi
Published: April 2022

We have proposed plausible reaction pathways involved in the chemical conversion of softwood lignin to vanillin through alkaline aerobic oxidation.
Facile preparation of N-doped graphitic carbon encapsulated nickel catalysts for transfer hydrogenolysis of lignin β-O-4 model compounds to aromatics
Authors: Tan Hua , Li Xuecheng , Ma Hao , Yang Xiaolin , Zhan Tong , Xie Wenyu , Wang Suhua , Zhu Jiaping
Published: April 2022

Graphitic N-doped carbon shell encapsulated Ni nanoparticles after strong acid leaching exhibited high activity and selectivity to aromatics in the conversion of lignin β-O-4 model compounds. The Cα–OH group was essential for product distributions.
Helical thienothiophene (TT) and benzothieno–benzothiophene (BTBT) derivatives: synthesis, structural characterization and semiconducting properties
Authors: Talamo Maurizio Mastropasqua , Pop Flavia , Hume Paul , Abbas Mamatimin , Wantz Guillaume , Avarvari Narcis
Published: April 2022

A double helicenic benzothieno–benzothiophene derivative, showing homochiral layers of MM and PP enantiomers in the single crystal phase, behaves as a p-type semiconductor in thin-film OFET devices fabricated by both spin coating and evaporation.
Transparent stretchable hydrogel sensors: materials, design and applications
Authors: Liu Yinping , Wang Lulu , Mi Yuanyuan , Zhao Sisi , Qi Simeng , Sun Meng , Peng Bo , Xu Quan , Niu Yingchun , Zhou Yang
Published: April 2022

Illustration of strain-, pressure-, temperature-, humidity- and gas sensor.
“Knowledge Without Action Means Nothing”: Stakeholder Insights on the Behaviors That Constitute Positive Change for Adults Who Stutter
Authors: Rodgers Naomi H. , Gerlach-Houck Hope
Published: April 2022

Purpose:

The aim of this study was to document the behaviors that adults who stutter (AWS) may engage in to make positive changes to living with stuttering.

Method:

We interviewed 23 key stakeholders, including 11 AWS and 12 speech-language pathologists who specialize in stuttering therapy. The semi-structured interviews began with the primary question, “If an adult who stutters was making positive changes to living with stuttering, what would they be doing?” Follow-up probing questions focused the interviews on identifying actionable behaviors that would suggest positive changes. The interviews were transcribed and qualitatively analyzed using applied and reflexive thematic analyses to develop multilevel themes.

Results:

Meaningful units extracted from the interviews contributed to three high-order global themes: (a) noticing and adjusting physical behaviors involved in speaking, to the extent that it is personally important to do so; (b) developing neutral or positive thoughts and feelings about stuttering; and (c) participating more fully in social and professional activities, even if the person stutters or thinks they might stutter. We developed 35 low-order basic themes, which we grouped into 11 mid-order organizing themes, to richly illustrate the three global themes.

Conclusions:

These findings extend the ongoing discussion regarding best practices for therapy targets in stuttering intervention. We identified measurable, multidimensional actions that clinicians can integrate in their therapy plans with AWS. While these actions represent a holistic approach to making positive changes, it grants clients and clinicians space to develop individualized intentions and outcomes.
Interval observer design for nonlinear systems using simplified contraction theory
Authors: Singh Bhawana , Xiong Xiaogang , Dinh Thach Ngoc , Kamal Shyam , Ghosh Sandip
Published: April 2022

In this work, vector framework based contraction theory to design interval observers for a class of nonlinear systems having disturbances, inputs and outputs is exploited. The main feature is that it does not require the formulation of error dynamics to show the convergence properties and need not require the construction of a Lyapunov candidate function without any idea of the structure of the function. Specifically, it performs the convergence analysis through a comparison system which has specified properties. Furthermore, this theory is exploited to design dynamic output feedback control through the obtained state bounds from the constructed interval observer and the system outputs, to make the interval observer to be globally asymptotically stable. Examples with simulation outcomes are provided to validate the theoretical results.
Bayesian adaptive direction detector in sample‐starved environment
Authors: Sha Minghui , Mao Erke , Meng Fei
Published: April 2022

Here, the problem of direction detection in disturbance with unknown covariance matrix is considered. The case that the number of the training data is too small to form an effective estimate for the unknown covariance matrix is focused upon. To solve the problem, the Bayesian framework is resorted to. Precisely, the unknown covariance matrix is assumed to be ruled by an inverse Wishart distribution. Then the problem is solved by the detector design criterion of generalized likelihood ratio test. Numerical examples indicate that the proposed detector can effectively detect the target, and provide higher probability of detection than the existing detectors even when sufficient training data are available.
Multi‐level refined power system operation mode analysis: A data‐driven approach
Authors: Li Yunyi , Bai Xiaoqing , Meng Jianling , Zheng Liqin
Published: April 2022

The high renewable penetration will cause the power system operation mode (PSOM) to change frequently. At present, the selection of PSOM mainly depends on the experience of relevant staff. However, selecting PSOM based on experience is difficult to comprehensively and elaborately analyze the possible PSOMs within a dispatching cycle, which inevitably invites troubles to the power system planning and dispatching. In this paper, a data‐driven analysis method is proposed, which integrates the techniques of preprocessing, dimensionality reduction, clustering, and data visualization of high‐dimensional data sets of power system operation. Simultaneously, qualitative and quantitative methods are used to analyze, evaluate the PSOM and their development laws. Finally, to verify the effectiveness of the proposed multi‐level refinement extraction method of PSOM, the normal power system operation mode (NPSOM), transition power system operation mode (TPSOM), extreme power system operation mode (EPSOM) are obtained and analyzed according to the real operation data of the urban power system. The abundant analysis results show that the proposed fine‐grained extraction method of PSOM is compelling, facilitating the power grid enterprise operation and planning.
Post‐fault operation strategy for single open‐phase fault in three‐phase induction motor drives
Authors: Abbasi Hadi , Ghanbari Mahmood , Ebrahimi Reza , Jannati Mohammad
Published: April 2022

Single open‐phase fault (SOPF) in three‐phase induction motor (TPIM) drives leads to undesired performances and in some cases shutdown of the drive system. This research proposes a post‐fault operation strategy based on direct rotor field‐oriented control (RFOC) technique for wye‐connected TPIM drives during SOPF. In the proposed control system, symmetrical and asymmetrical transformation matrices are utilized for stator voltage and current variables, respectively. In addition, an extended Kalman filter (EKF) is used for the rotor flux estimation, filtration of stator currents, and obtaining their time derivatives. The performance of the introduced technique including steady and transient states during different reference speeds is experimentally validated for a wye‐connected TPIM drive considering SOPF. Additionally, the performance of the proposed strategy is experimentally compared with conventional RFOC strategies.
Study of the consistency of defrosted aerated fermented milk desserts by rheological methods
Authors: Gurskiy Igor , Tvorogova Antonina
Published: April 2022

The aim of the research was to quantify the consistency of defrosted aerated fermented milk desserts. The objects of research were samples of desserts with a mass fraction of fat of 2.5%, in one of the samples whey protein concentrate was used (WPC). Rotational viscometry, penetrometric and thermostatic methods were used. It has been established that the use of WPC allows increasing dynamic viscosity by 4.5 times, mixture overrun by 1.4 times, dimensional stability (less shrinkage degree) by 1.26 times, adhesion by 1.65 times and stickiness by 1.93 times. Also, the hardness decreases by 1.6 times and the elastic modulus by 1.65 times. The results obtained are of practical importance in substantiating the composition, parameters of the production process and the sale of defrosted aerated fermented milk desserts.
Micromobility and smart cities: efficiency, energy consumption and range analysis for electric vehicles
Authors: Alcázar-García Désirée , Martínez Luis Romeral
Published: April 2022

Climate change and smart cities are topics where a large number of resources are being invested to avoid it and advance its development respectively. This paper presents a calculation procedure of the car efficiency, energy consumption and range whose efficiency has already been tested for hybrid vehicles (including plug-in) and fuel cell vehicles, as well as pure electric vehicles of category M1. This method has been adapted for quadricycles of category L6e and L7e in order to be able to use it to accelerate the design of this type of vehicles and contribute to its introduction in Smart Cities. The reliability of the system has been verified with commercially available vehicles and prototypes taking into account their technical specifications: electric motor (e.g., permanent magnet motor), technology of energy storage system (e.g., lithium-ion battery), weight and geometry of the car for all types of drive cycles. According to the literature review, there is currently no standardized operating system or hardware abstraction layer for such methodology/application in the automotive sector. This flexible method can be easily extended for different technologies of batteries and electric motors, different standard or customized drive cycles, etc. Besides, it has high reliability for vehicles of category L since in no case does the error reach 5 % and the average value is 2.5 % when real data from vehicle manufacturers and outcomes are compared. Thus, results show the consistency of the system.
Post-laminectomy Dorsal Cord Migration Resulting in Immediate Neurologic Deterioration during Ventral Meningioma Resection: Proposed Mechanism of Injury and Prevention Technique
Authors: Harel Ran , Kimchi Gil , Perry Avital , Korn Akiva , Knoller Nachshon
Published: April 2022

Background Ventral thoracic meningiomas may pose a technical challenge owing to a limited surgical corridor and the presence of long-standing ventral cord compression. Unopposed dorsal spinal cord migration may occur following a laminectomy resulting in immediate neurologic injury. We discuss the possible mechanism underlying such a phenomenon, suggesting alternative approach to prevent neurologic injury.

Methods Two patients operated on for ventral thoracic meningioma and sustained neurologic compromise were retrospectively evaluated. Image editing software was used for 3D modeling to simulate the possible underlying mechanism of injury. Cases where ventral thoracic meningiomas were approached via unilateral hemilaminectomy, performed in 2020, were retrospectively analyzed and compared with the laminectomy approach cohort.

Results Two patients sustained postoperative neurologic function decline following resection of ventral thoracic meningioma via the laminectomy approach. Both exhibited permanent abolishment of transcranial motor evoked potentials (MEPs) following laminectomy. Based on the extrapolated 3D models for these two cases, dorsal cord migration was postulated as the cause for the acute neurologic compromise.

Conclusion Laminectomy for resection of thoracic ventral meningioma may lead in some cases to dorsal cord migration resulting in grave neurologic deterioration. Unilateral approach to these tumors restricts the dorsal migration and may mitigate neurologic outcomes.
Meningeal Metastasis Causing Chronic Subdural Hematoma in a Cancer Patient with Bilateral Papilledema and Suspected Cerebral Venous Thrombosis: A Case Report
Authors: Pangratz-Daller Cornelia , Grimm Jochen , Pfaff Johannes A.R. , Kraus Theo F.J. , Sotlar Karl , Rahman Al-Schameri Abdul , Kral Michael , Griessenauer Christoph J. , Schwartz Christoph
Published: April 2022

Meningeal metastasis has been reported as a very rare cause of chronic subdural hematoma (CSH). Here, we report a female patient who had undergone initial burr hole drainage of a CSH at an outside hospital. Postoperatively, the patient additionally suffered from visual impairment due to bilateral papilledema and the patient was eventually transferred to our neurosurgical department for additional treatment. A craniotomy was performed and due to intraoperative suspicious findings, histopathologic samples were obtained that revealed a metastasis of thus far undiagnosed triple negative breast cancer. Furthermore, the patient was suspected to have a partial cerebral venous thrombosis (CVT). Our case report addresses this extremely rare clinical constellation. We provide a detailed overview on our patient's clinical and radiologic course, and discuss the potential association of CSH with meningeal metastasis and bilateral papilledema.
The Role of Diskectomy in Reducing Infectious Complications after Surgery for Lumbar Spondylodiscitis
Authors: Schatlo Bawarjan , Rohde Veit , Abboud Tammam , Janssen Insa , Melich Patrick , Meyer Bernhard , Shiban Ehab
Published: April 2022

Background Surgery for pyogenic Spondylodiscitis as an adjunct to antibiotic therapy is an established treatment. However, the technique and extent of surgical debridement remains a matter of debate. Some propagate diskectomy in all cases. Others maintain that stand-alone instrumentation is sufficient.

Methods We reviewed charts of patients who underwent instrumentation for pyogenic Spondylodiscitis with a minimum follow-up of 1 year. Patients were stratified according to whether they underwent diskectomy plus instrumentation or posterior instrumentation alone. Outcome measures included the need for surgical revision due to recurrent epidural intraspinal infection, wound revision, and construct failure.

Results In all, 257 patients who underwent surgery for pyogenic Spondylodiscitis were identified. Diskectomy and interbody procedure (group A) was performed in 102 patients, while 155 patients underwent instrumentation surgery for Spondylodiscitis without intradiskal debridement (group B). The mean age was 67 ± 12 years, and 102 patients (39.7%) were females. No significant differences were found in the need for epidural abscess recurrence therapy (group A [2.0%] and 5 cases in group B [3%; p = 0.83]) and construct failure (p = 0.575). The need for wound revisions showed a tendency toward higher rates in the posterior instrumentation–only group, which failed to reach significance (p = 0.078).

Conclusions Overall, intraspinal relapse of surgically treated pyogenic diskitis was low in our retrospective series. The choice of surgical technique was not associated with a significant difference. However, a somewhat higher rate of wound infections requiring revision in the group where no diskectomy was performed has to be weighed against a longer duration of surgery in an already ill patient population.
Evaluation of High-Risk Human Papillomavirus Testing in Women with Atypical Squamous Cells of Undetermined Significance to Detect Cervical Intraepithelial Neoplasia
Authors: Kawase Rieko , Suzuki Shunji
Published: April 2022

Introduction We retrospectively examined the changes in the management and outcomes of the cases with atypical squamous cells of undetermined significance (ASC-US) according to the Bethesda system (TBS).

Materials and Methods Between May 2009 and December 2018, 432 cases with ASC-US were retrospectively examined for the implementation of high-risk human papillomavirus (hrHPV) testing and/or cervical biopsy and clinical courses.

Results The hrHPV testing was performed in 277 cases (64.1%). Of these, there were 80 with positive hrHPV (28.9%). Of the 80 cases, cervical biopsy was performed in 71 (88.9%) cases based on the finding of colposcopy. Cervical intraepithelial neoplasia (CIN) was diagnosed in 55 cases (77.4%). The sensitivity, specificity, positive predictive value, and negative predictive value of CIN diagnosis by hrHPV testing in cases of ASC-US were 72.5, 95.0, 88.7, and 86.3%, respectively (p < 0.01).

Conclusion The conducting of hrHPV test on women who were evaluated as ASC-US according to TBS affirmed its clinical usefulness.
A Case Report of Early-Onset Frey's Syndrome in an Infant
Authors: Pavlovic Momcilo
Published: April 2022

The appearance of flushing in the territory of the auriculotemporal nerve after ingestion of foods with a sweet, salty, or sour flavor could suggest Frey's syndrome, especially if the infant has a history of obstetric trauma. This rare and benign condition requires no diagnostic exploration or treatment. A 3-month-old male infant presented with facial flushing since he was 6 weeks' old. Episodes of flushing were stereotypical, over the zone innervated by the left auriculotemporal nerve. They started 10 to 15 seconds after the beginning of the feeding and disappeared after 15 to 20 minutes. At the time of the onset of facial erythema, the infant was exclusively bottle feeding. Diagnosis of Frey's syndrome was made on historical and clinical grounds, and no further testing was needed. Flushing gradually started to fade at the age of 5 months and completely disappeared after 8 months. Introducing solid food did not cause any deterioration of facial erythema. Early recognition of Frey's syndrome is important to avoid unnecessary investigation and therapy. On the other hand, our reported case warns that Frey's syndrome may occur in very early infancy without ingestion of solid food.
A fast Tikhonov regularization method based on homotopic mapping for electrical resistance tomography
Authors: Li Shouxiao , Wang Huaxiang , Liu Tonghai , Cui Ziqiang , Chen Joanna N. , Xia Zihan , Guo Qi
Published: April 2022

Electrical resistance tomography (ERT) is considered a novel sensing technique for monitoring conductivity distribution. Image reconstruction of ERT is an ill-posed inverse problem. In this paper, an improved regularization reconstruction method is presented to solve this issue. We adopted homotopic mapping to choose the regularization parameter of the iterative Tikhonov algorithm. The standard normal distribution function was used to continuously adjust the regularization parameter. Subsequently, the resultant image vector was deployed as the initial value of the iterative Tikhonov algorithm to improve the image quality. Finally, the improved method was combined with a projection algorithm based on the Krylov subspace, which was also effective in reducing the computational time. Both simulation and experimental results indicated that the new algorithm could improve the real-time performance and imaging quality.
Variable repetition frequency asynchronous optical sampling method without a feedback loop
Authors: Nagakubo A. , Kanai K. , Tamura H. , Tange A. , Ogi H.
Published: April 2022

The ultrafast pump–probe measurement represents a key technique to study fs–ps dynamics. The asynchronous optical sampling (ASOPS) method realizes fast and long time-range measurement with high time resolution using different repetition frequency pump–probe light pulses. The frequency difference Δf is an important parameter, as it dictates the measurement time and time resolution. However, usual ASOPS measurements require a complex and precise stabilizer to control Δf or it is difficult to change Δf. In this study, we use two free-running titanium/sapphire pulse lasers to develop a variable repetition frequency ASOPS (VRF-ASOPS) method without a stabilizer or feedback loop, where we can easily alter Δf by changing the cavity length of the probe light laser. To detect the coincidences of the pump–probe light pulses, we cause the instantaneous reflectivity change in a 100 nm platinum film by irradiating the pump light and observe it by the probe light. We use this signal as the trigger signal to directly determine Δf, which enables us to average and convert the measured responses without a stabilizer or feedback loop. Using this VRF-ASOPS system, we obtain pulse echo signals and 100 GHz Brillouin oscillations, which are equivalent to those measured by the mechanical delay line method, confirming the validity of our developed method.
Tin-lead-metal halide perovskite solar cells with enhanced crystallinity and efficiency by addition of fluorinated long organic cation
Authors: Pitaro Matteo , Pau Riccardo , Duim Herman , Mertens Martijn , Van Gompel Wouter T. M. , Portale Giuseppe , Lutsen Laurence , Loi Maria Antonietta
Published: April 2022

Highly performing mixed Sn/Pb-metal halide perovskite solar cells (PSCs) are among the most promising options to reduce Pb content in perovskite devices and enable, owing to their reduced bandgap, the fabrication of all-perovskite tandem solar cells. Whereas pure-Pb perovskite devices exhibit efficiency up to 25.5%, alongside a high open-circuit voltage (≈1.2 V), Sn-Pb PSCs still show lower performances (22.2%) due to higher open-circuit voltage losses. Here, we introduced 2,3,4,5,6-pentafluorophenethylammonium cations in a perovskite active layer of composition (FASnI3)0.5(MAPbI3)0.5 to obtain highly oriented films with improved thermal stability. The treated films exhibit merged grains with no evidence of 2D structures, which could help to reduce the trap state density at the surface and grain boundaries. Solar cells fabricated with the fluorinated cation added to the active layer displayed reduced trap-assisted recombination losses and lower background carrier density, which leads to enhanced open-circuit voltages with respect to the reference samples and the active layers incorporating unfluorinated phenethylammonium cations. The best device reached an efficiency of 19.13%, with an open-circuit voltage of 0.84 V, which is substantially improved with respect to the reference sample showing 17.47% efficiency and 0.77 V open-circuit voltage. More importantly, the fluorinated cations' addition is instrumental to improve the device's thermal stability; 90.3% of the solar cell initial efficiency is maintained after 90 min of thermal stress at 85 °C in a nitrogen atmosphere.
Multi-stable acoustic metamaterials with re-configurable mass distribution
Authors: Frazier Michael J.
Published: April 2022

This article proposes a design strategy for acoustic metamaterial lattices which leverages the characteristic multi-stability and kinematic amplification of the internal architecture to realize a re-configurable effective mass distribution, enabling a corresponding frequency band structure of extreme tunability. The approach builds metamaterial lattices from bi-stable elastic elements featuring the typical two-bar inertial amplification mechanism, whose deformation axis is uniquely misaligned with that of its elastic support such that the realized amplification is configuration-specific. Conveniently, a change in the configuration does not simultaneously alter the element dimensions and, therefore, the size/shape of the finite metamaterial structure remains constant. Moreover, as the multi-stability and kinematic amplification are each based on geometry, scaling the resulting metamaterial structure is expected to be straightforward. The dynamic performance of 1D/2D metamaterial architectures exhibiting the proposed design strategy is analytically determined via Bloch wave analysis and supported by numerical demonstration of the corresponding finite structures.
Composition dependence of thermophysical properties for liquid Zr–V alloys determined at electrostatic levitation state
Authors: Zheng C. H. , Zou P. F. , Hu L. , Wang H. P. , Wei B.
Published: April 2022

The thermophysical properties of liquid Zr–V alloys covering a whole composition range were systematically measured by an electrostatic levitation technique. A series of maximum undercoolings from 150 to 386 K (0.2 TL) was achieved for 11 different liquid alloys under containerless state and radiative cooling conditions, where Zr83.5V16.5 and Zr20V80 alloys displayed the strongest undercooling ability. The densities of liquid Zr–V alloys were measured over a wide temperature range from overheated to undercooled states, and the results exhibited a linear dependence on temperature for all 11 compositions. Two typical solidification pathways were observed for hypoeutectic alloys. Except for a slowing down of decreasing tendency near a eutectic Zr57V43 alloy, the liquid densities of Zr–V alloys almost decrease linearly with increasing V content. Accordingly, the thermal expansion coefficients of Zr–V alloys were also derived from containerless measurements, and they showed an increasing tendency with V content. Since thermal radiative dominated the heat transfer process, the ratio of isobaric specific heat to hemispherical emissivity was directly deduced from the thermal balance equation, leading to a quadratic relationship with temperature. It was found that the increase of V content enhanced the ability of radiative heat dissipation below 16.5 at. % V content.
On the validity of quasilinear theory applied to the electron bump-on-tail instability
Authors: Crews D. W. , Shumlak U.
Published: April 2022

The accuracy of quasilinear theory applied to the electron bump-on-tail instability, a classic model problem, is explored with conservative high-order discontinuous Galerkin methods applied to both the quasilinear equations and to a direct simulation of the Vlasov–Poisson equations. The initial condition is chosen in the regime of beam parameters for which quasilinear theory should be applicable. Quasilinear diffusion is initially in good agreement with the direct simulation but later underestimates the turbulent momentum flux. The greater turbulent flux of the direct simulation leads to a correction from quasilinear evolution by quenching the instability in a finite time. Flux enhancement above quasilinear levels occurs as the phase space eddy turnover time in the largest amplitude wavepackets becomes comparable to the transit time of resonant phase fluid through wavepacket potentials. In this regime, eddies effectively turn over during wavepacket transit so that phase fluid predominantly disperses by eddy phase mixing rather than by randomly phased waves. The enhanced turbulent flux of resonant phase fluid leads, in turn, through energy conservation to an increase in non-resonant turbulent flux and, thus, to an enhanced heating of the main thermal body above quasilinear predictions. These findings shed light on the kinetic turbulence fluctuation spectrum and support the theory that collisionless momentum diffusion beyond the quasilinear approximation can be understood through the dynamics of phase space eddies (or clumps and granulations).
Correct interpretation of actinomycete imagery using scanning electron microscopy
Authors: Kurtböke D. İpek
Published: April 2022

Antibiotic discovery was one of the most significant advances in therapeutic medicine following the advances in fermentation technology owing to Howard Florey and his associates. The ‘Golden era’ of antibiotics following the first discoveries in the laboratory of Waksman and his colleagues from a group of microorganisms known as actinomycetes lasted for 34 years (1940–1974). These fascinating microorganisms especially the members of the genus Streptomyces gave us the majority of the known antibiotics we use today, like streptomycin, kanamycin, neomycin, gentamicin, vancomycin and many more. To be able to produce these antibiotics in large-scale, the producer actinomycetes had to be selectively isolated. This resulted in a collaboration of over 40 laboratories from 18 different countries called ‘The International Streptomyces Project (ISP)’. The isolates generated in this project were studied in-depth including their morphologies together with their bioactivity. One of the components of these investigation was the correct interpretation of actinomycete morphology including the use of scanning electron microscopy. At the end of the first European Actinomycete Conference in Bradford University in England (1984), I had the opportunity to be trained by late Professor Cross on actinomycete growth morphologies. Thirty-eight years later when I witness the frequent difficulties students encounter in the interpretation of the actinomycete SEM images, I decided to write this paper and pass the skills given to me by late Professor Cross to the younger generation.
Structural basis of protein substrate processing by human mitochondrial high-temperature requirement A2 protease
Authors: Toyama Yuki , Harkness Robert W. , Kay Lewis E.
Published: April 2022

Significance

Protein aggregates are often toxic, leading to impaired cellular activities and disease. The human HtrA2 trimeric enzyme cleaves such aggregates, and mutations in HtrA2 are causative for various neurodegenerative disorders, such as Parkinson’s disease and essential tremor. The mechanism by which cleavage occurs has been studied using small peptides, but little information is available as to how HtrA2 protects cells from the pathologic effects of aggregation involving protein molecules that can form well-folded structures. Using solution NMR spectroscopy, we investigated the structural dynamics of the interaction between HtrA2 and a model protein substrate, demonstrating that HtrA2 preferentially binds to an unfolded substrate ensemble and providing insights into how HtrA2 function is regulated.
Fabrication and flow rate characterization of a DRIE process based valveless piezoelectric micropump
Authors: Şimşek Sevda , Vahid Ebrahimpour Ahmadi , Çelik Süleyman , Sayar Ersin , Koşar Ali
Published: April 2022

Micropumps have become one of the major research topics in the field of microfluidics. Different actuators have been used in active micropumps including piezoelectric ones, which convert electrical energy to mechanical energy. In this study, a piezoelectric disc was designed as an actuator and was integrated into a fabricated piezoelectric micropump. Unlike wet etching methods, which is generally used to etch layers of relatively high thickness in the silicon wafer, dry etching was used in this study. Aluminum was used as a mask material during the fabrications-steps, and the fabrication process was shortened with the use of the masking steps. The etching process of the slot, in which the piezoelectric disc was placed, and etching of the inlet/outlet channels were performed simultaneously. Thus, the processing time was significantly shortened. The fabrication of this silicon-based valveless micropump was accomplished by using the DRIE (deep reaction-ion etching) technique, which provided controlled etching. Experiments were conducted on the fabricated micropump with the use of the bulk micromachining technology to deliver the desired pumping action. The leakage and the air entrapment between the consecutive micropump structural layers were satisfactorily eliminated. This micropump is capable of delivering a promising flow rate of 52 (µl min−1) for deionized water, which corresponds to a 150 [Hz] square wave type and a peak-to-peak voltage of 60 (V)Vp-p. No moving mechanical valves were included so that the risks of clogging, reduced performance, and reduced reliability due to wear and fatigue were minimized. Not only gases and liquids but also fluids containing particles could be used as the working fluid for this micropump. The piezoelectric micropump design was optimized to achieve a high time-averaged flow rate (>50 (µl min−1)) with a relatively low excitation voltage (<100 (V)Vp-p) as opposed to the use of a high excitation voltage.
On the importance of electron–electron and electron–phonon scatterings and energy renormalizations during carrier relaxation in monolayer transition-metal dichalcogenides
Authors: Hader Jörg , Neuhaus Josefine , Moloney Jerome V , Koch Stephan W
Published: April 2022

An ab initio based fully microscopic many-body approach is used to study the carrier relaxation dynamics in monolayer transition-metal dichalcogenides. Bandstructures and wavefunctions as well as phonon energies and coupling matrix elements are calculated using density functional theory. The resulting dipole and Coulomb matrix elements are implemented in the Dirac–Bloch equations to calculate carrier–carrier and carrier–phonon scatterings throughout the whole Brillouin zone (BZ). It is shown that carrier scatterings lead to a relaxation into hot quasi-Fermi distributions on a single femtosecond timescale. Carrier cool down and inter-valley transitions are mediated by phonon scatterings on a picosecond timescale. Strong, density-dependent energy renormalizations are shown to be valley-dependent. For MoTe2, MoSe2 and MoS2 the change of energies with occupation is found to be about 50% stronger in the Σ and Λ side valleys than in the K and K′ valleys. However, for realistic carrier densities, the materials always maintain their direct bandgap at the K points of the BZ.
Half-topological state in magnetic topological insulators
Authors: Tran Minh-Tien , Tran Thanh-Mai Thi
Published: April 2022

We predict a novel topological state, half-topological state, in magnetic topological insulators. The topological state is characterized by different topologies of electrons with different spin orientations, i.e., electrons with one spin orientation occupy a nontrivial topological insulating state, while electrons with opposite orientation occupy another insulating state with trivial topology. We demonstrate the occurrence of the half-topological state in magnetic topological insulators by employing a minimal model. The minimal model is a combination of the spinful Haldane and the double-exchange models. The double-exchange processes maintain a spontaneous magnetic ordering, while the next-nearest-neighbor hopping in the Haldane model gives rise to a nontrivial topological insulator. The minimal model is studied by applying the dynamical mean field theory. It is found that the long-range antiferromagnetic ordering drives the system from either topological or topologically trivial antiferromagnetic insulator to the half-topological state, and finally to topologically trivial antiferromagnetic insulator. The equations for the topological phase transitions are also explicitly derived.
Informative singular value decomposition and its application in fault detection of planetary gearbox
Authors: Shen Zhaoyang , Shi Zhanqun , Shen Guoji , Zhen Dong , Gu Fengshou , Ball Andrew
Published: April 2022

The fault features of planetary gearboxes are modulated complexly and are submerged by other signal components, for its vibration signal has the characteristics of multi-source and multi transmission path. A fault detection method of planetary gearboxes based on informative singular value decomposition and envelope spectrum analysis (ISVD-ESA) is proposed in this paper. In this method, the advantage of blind source separation of singular value decomposition (SVD) method is combined with the ability of negentropy and cyclic autocorrelation (CA) in non-Gaussian characteristics recognition. The fast SVD is firstly performed to decompose the vibration signal into a series of singular value decomposition component signals (SVCSs). Secondly, the detector of negentropy combined with CA is applied to estimate the fault informativeness of each SVCS. The SVCSs are amplified by the fault informativeness and reconstructed to the out signal of ISVD. Finally, the fault features can be extracted by the ESA from the output signal of ISVD. The performance of the proposed method is verified by simulation and experimental studies. Results show that the proposed ISVD-ESA strategy can enhance the weak features of multi-modulation and accurately extract the faults of tooth tip pitting and misalignment of sun gear of the planetary gearbox.
DC and optical signatures of the reconstructed Fermi surface for electrons with parabolic band
Authors: Rukelj Zoran , Radić Danko
Published: April 2022

We study the main intra-band and inter-band transport properties at zero temperature of free electron-like system undergoing a topological reconstruction of the Fermi surface for the two-dimensional and three-dimensional case. The calculated intra-band properties include the single-particle density of states, the total and the effective concentrations of electrons and the thermopower. As for the inter-band case, the real part of the conductivity has been calculated within the vanishing inter-band relaxation approximation as a function of the incident photon energy. Within this approach, it is shown that the optical conductivity has a nonvanishing component parallel to the reconstruction wave vector and the shape which depends on the value of the Fermi energy. Each dimensionality has its particular features in the transport quantities presented in the paper, which are discussed and compared with those in the free electron scenario. Finally, we identify the signature of the topological reconstruction of the Fermi surface in the intra-band and inter-band transport functions.
Phase synchronization versus modulational instability for zonal flow generation and pattern formation
Authors: Yi Sumin , Jhang Hogun , Kim S.S. , Kwon Jae-Min
Published: April 2022

From global gyrokinetic simulations of toroidal ion temperature gradient-driven (ITG) turbulence, we identify two distinguished regimes where zonal flow generation and its radial pattern formation is governed by either phases or amplitudes of the turbulence spectrum. When the unstable region is wider than the correlation length of ITG modes, the zonal flow structure changes in a turbulence time scale. We newly uncover that the radial phases of ITG modes determine the evolution of the zonal flow structure. Synchronization of mode phases induced by the global zonal flow drives a fine-scale zonal flow pattern. With a narrow unstable region comparable to the mode correlation length, the phase effect almost vanishes. In this regime, we recover that the modulational instability promptly amplifies a coherent zonal flow, leading to a lower turbulence saturation level. This finding explains the reduction of turbulent transport at a narrow width of the strong gradient region, which has been attributed to the system size effects in ion-scale gyrokinetic turbulence.
Compaction history based on porosity, pressure and temperature relation in Central Luconia province, offshore Sarawak
Authors: Refael  , Jamaludin Siti Nur Fathiyah , Latiff Abdul Halim Abdul
Published: April 2022

This study investigates the role of porosity in relation to temperature and pressure within Miocene-Pliocene sediments in Central Luconia province. The main objective is to understand the effect on porosity loss within Miocene-Pliocene sediments as part of the compaction of the sediments through time. The methodology involves seismic interpretation of 2D seismic lines and analysis of four wells over the central complex in Central Luconia province. Thick sedimentation was found within the clastic sediments of Cycle VI, indicating major clastic influx from the deltas and onshore of Sarawak during Pliocene. These clastic sediments had become a major source of weight in the offshore basin, inducing compaction within the older formations. Porosity distributions based on the wells showed that Cycle VI had the highest porosity in LH1 well with 33.77% porosity, while porosity within Cycle IV & V limestone showed an average porosity of 22% in all wells. Porosities within Cycle III and Cycle II were observed to be average of 16%. The porosity within the reservoir rock was reduced as the depth increased. This porosity reduction was relatively due to the compaction of the sediments, linked with the changes of pressure and temperature indicated by several evidences found in each well. Overpressure zone affects irregularity of porosity reduction with depth, whereas high temperature promotes diagenetic reaction that causes sudden porosity loss. Nevertheless, a sudden increase in porosity was also observed at the top of Cycle IV & V limestone due to a major drop in the sea level during the Early Late Miocene, which had encouraged the karstification process, inducing secondary porosity. This study has proved that compaction within Miocene-Pliocene sediments is not only related to the loss in porosity, but it involves changes in pressure and temperature regime of sediments and is highly dependent on the natural changes of sea level.
Discriminating seismic amplitude pitfall by low saturation gas using controlled-source electromagnetic technology
Authors: Salleh Nur Farhana , Hermana Maman , Basit Amatul Syafi Abdul
Published: April 2022

One of false positives in seismic amplitude associates with the presence of low saturation gas. The amplitude response is ambiguous prominently in shallow subsurface due to similar amplitude of fizz gas to highly saturated gas reservoir. This pitfall is demonstrated in Gassmann’s fluid substitution modelling which drastic velocity reduction is modeled by 5% of gas. The strong reduction induces anomalous bright spot in seismic similarly manifested by a highly gas reservoir. In pore fluid characterization, seismic amplitude of a brine reservoir is well distinguished from gas by change of response polarity from negative to positive amplitude due to higher brine modulus than gas. To a lesser extent, the negative amplitude of gas sand almost identical between commercial and non-commercial gas trap and difficult to distinguish in seismic. The similar negative amplitude of the gas cases caused by a very low gas modulus resulting to sudden drop of rock bulk modulus despite with the presence of low gas percentage. Thus, seismic velocity slows down when travels through a gas sand medium. Integration of controlled-source electromagnetic (CSEM) method in hydrocarbon prediction reduces exploration risk by only detecting commercial hydrocarbon. It exploits resistivity contrast between overburden and hydrocarbon reservoir which highly controlled by hydrocarbon saturation. CSEM normalized response exceeds the cut off response by a minimum saturation of 70% of gas. Less than 70% of gas, CSEM response is below the cut off response which considered as insignificant anomaly in CSEM measurement. It becomes a key strength as this method reduces amplitude uncertainty in seismic due to low saturation gas and potentially improves the chances of economic discovery in hydrocarbon exploration.