bluuebunny/crossref_metadata_2025 huggingface dataset:
Seasonal predictability of baroclinic wave activity
Authors: Zhang Gan , Murakami Hiroyuki , Cooke William F. , Wang Zhuo , Jia Liwei , Lu Feiyu , Yang Xiaosong , Delworth Thomas L. , Wittenberg Andrew T. , Harrison Matthew J. , Bushuk Mitchell , McHugh Colleen , Johnson Nathaniel C. , Kapnick Sarah B. , Tseng Kai-Chih , Zhang Liping
Published: October 2021

Midlatitude baroclinic waves drive extratropical weather and climate variations, but their predictability beyond 2 weeks has been deemed low. Here we analyze a large ensemble of climate simulations forced by observed sea surface temperatures (SSTs) and demonstrate that seasonal variations of baroclinic wave activity (BWA) are potentially predictable. This potential seasonal predictability is denoted by robust BWA responses to SST forcings. To probe regional sources of the potential predictability, a regression analysis is applied to the SST-forced large ensemble simulations. By filtering out variability internal to the atmosphere and land, this analysis identifies both well-known and unfamiliar BWA responses to SST forcings across latitudes. Finally, we confirm the model-indicated predictability by showing that an operational seasonal prediction system can leverage some of the identified SST-BWA relationships to achieve skillful predictions of BWA. Our findings help to extend long-range predictions of the statistics of extratropical weather events and their impacts.
Development of deep learning-based detecting systems for pathologic myopia using retinal fundus images
Authors: Lu Li , Zhou Enliang , Yu Wangshu , Chen Bin , Ren Peifang , Lu Qianyi , Qin Dian , Lu Lixian , He Qin , Tang Xuyuan , Zhu Miaomiao , Wang Li , Han Wei
Published: October 2021

Globally, cases of myopia have reached epidemic levels. High myopia and pathological myopia (PM) are the leading cause of visual impairment and blindness in China, demanding a large volume of myopia screening tasks to control the rapid growing myopic prevalence. It is desirable to develop the automatically intelligent system to facilitate these time- and labor- consuming tasks. In this study, we designed a series of deep learning systems to detect PM and myopic macular lesions according to a recent international photographic classification system (META-PM) classification based on color fundus images. Notably, our systems recorded robust performance both in the test and external validation dataset. The performance was comparable to the general ophthalmologist and retinal specialist. With the extensive adoption of this technology, effective mass screening for myopic population will become feasible on a national scale.
Host methylation predicts SARS-CoV-2 infection and clinical outcome
Authors: Konigsberg Iain R. , Barnes Bret , Campbell Monica , Davidson Elizabeth , Zhen Yingfei , Pallisard Olivia , Boorgula Meher Preethi , Cox Corey , Nandy Debmalya , Seal Souvik , Crooks Kristy , Sticca Evan , Harrison Genelle F. , Hopkinson Andrew , Vest Alexis , Arnold Cosby G. , Kahn Michael G. , Kao David P. , Peterson Brett R. , Wicks Stephen J. , Ghosh Debashis , Horvath Steve , Zhou Wanding , Mathias Rasika A. , Norman Paul J. , Porecha Rishi , Yang Ivana V. , Gignoux Christopher R. , Monte Andrew A. , Taye Alem , Barnes Kathleen C.
Published: October 2021

Background

Since the onset of the SARS-CoV-2 pandemic, most clinical testing has focused on RT-PCR1. Host epigenome manipulation post coronavirus infection2–4suggests that DNA methylation signatures may differentiate patients with SARS-CoV-2 infection from uninfected individuals, and help predict COVID-19 disease severity, even at initial presentation.

Methods

We customized Illumina’s Infinium MethylationEPIC array to enhance immune response detection and profiled peripheral blood samples from 164 COVID-19 patients with longitudinal measurements of disease severity and 296 patient controls.

Results

Epigenome-wide association analysis revealed 13,033 genome-wide significant methylation sites for case-vs-control status. Genes and pathways involved in interferon signaling and viral response were significantly enriched among differentially methylated sites. We observe highly significant associations at genes previously reported in genetic association studies (e.g.IRF7,OAS1). Using machine learning techniques, models built using sparse regression yielded highly predictive findings: cross-validated best fit AUC was 93.6% for case-vs-control status, and 79.1%, 80.8%, and 84.4% for hospitalization, ICU admission, and progression to death, respectively.

Conclusions

In summary, the strong COVID-19-specific epigenetic signature in peripheral blood driven by key immune-related pathways related to infection status, disease severity, and clinical deterioration provides insights useful for diagnosis and prognosis of patients with viral infections.
Photoinduced electronic and ionic effects in strontium titanate
Authors: Siebenhofer Matthäus , Viernstein Alexander , Morgenbesser Maximilian , Fleig Jürgen , Kubicek Markus
Published: October 2021

Illumination of SrTiO3 induces a multitude of electronic and ionic effects. Recent advances in photoconductivity, photoluminescence, photovoltage, photochromism and photocatalysis are highlighted.
One catalyst for two uses: TiOx–C acts as either a photocatalyst or thermocatalyst to promote reductive amination
Authors: Wang Shun , Tong Xinli , Meng Lingwu , Zhao Yujun
Published: October 2021

Titanium oxide uniformly doped with carbon (TiOx–C) efficiently promotes the reductive amination of aliphatic aldehydes as a catalyst not only under visible light but also under heating conditions.
Tribomechanical Properties of the Modified Surface of Alloys of the WC-Co System
Authors: Oskolkova Tatyana , Yaresko Sergey , Balakirov Sergey
Published: October 2021

The research results of tribological characteristics of the surface hardened by electric explosion alloying of tungsten-cobalt hard alloys with carbon, titanium and aluminum are presented. The correlation of tribomechanical properties of the modified surface of alloys with changes in the structure and phase composition of the surface layer of the material is established. It is shown that the best wear characteristics are achieved during hardening of alloys by electric explosion of titanium. In this case, the coefficient of friction decreases by almost 3 times, the wear resistance estimated by the depth of the wear track increases by more than 10.0 times, and by the area of the wear track – by 53.2 times.
Applying of Pressing Technology to Forming Finger-Joint Profile for Wood Splicing
Authors: Rubleva Olga
Published: October 2021

Splicing of wood lengthwise is widely used in the manufacture of various products. The basic method of forming the finger joint profile is milling. This method has a number of disadvantages: high cost of the milling tool, necessity of its periodic sharpening; high energy consumption of the milling process, design constraints on the geometric parameters and strength of fingers (tenons). An alternative to milling is a new way of forming such joints elements as mortise and tenons by pressing along the grain. This method allows obtaining mortises in the form of fairly accurate rectangular imprints on the ends of the blanks. The use of a punching tool instead of a cutting one avoids chips and reduces the cost of the aspiration system. Previously, rectangular tenons were used only for L-type box joints. The aim of the study is to prove the possibility of using the cold end pressing technology to form the mortises and tenons profile for end joining that meet regulatory requirements. A series of experiments on pressing the elements of joints profile in the form of multiple tenons has shown that the achieved accuracy and roughness meet the requirements for the manufacture of joints intended for lengthwise splicing. Assessment of the strength of the joints showed their compliance with the regulatory requirements. The conducted research confirms confirms the possibility of using the pressing technology to form the profile of the finger joint for wood splicing.
Theoretical-Probability Model for Calculating Roofness in Magnetic Abrasive Machining
Authors: Ikonnikov Alexey , Leonov Sergey
Published: October 2021

The work is devoted to the problem of calculating the surface roughness during magnetic abrasive processing. Cutting grains have random dimensional characteristics, are randomly located on the surface of the tool, the workpiece has an irregular profile. The cutting parts of the grains partially remove the chips and partially elastoplastically deform the metal. Some of the vertices fall into the marks on the surface of the workpiece formed by the previous processing, and some - on the marks from the passage of the previous vertices. This process is determined by the probability of contact of the top of the grain with the metal. The developed probabilistic-theoretical model makes it possible to predict the removal of metal from the treated surface depending on the time and parameters of the operation, which creates the prerequisites for their use in the design of polishing operations.
Composite Corundum Ceramics with Reinforcing Carbon Nanotubes Modified with Eutectic Additives
Authors: Antonov Dmitriy , Pavlov Stepan , Makarov Nikolay
Published: October 2021

The characteristics of composite materials of Al2O3 system - carbon nanotubes - eutectic additives are investigated. The influence of the reinforcing component content, as well as the mode of high-temperature heat treatment in vacuum on the strength properties of the material are considered. Samples with a mass content of carbon tubes of 0.4% were obtained. These samples had the following characteristics: an average tensile strength at three-point bending of 380 MPa, an open porosity of 0.9%, an average density of 3.71 g/cm3.
Stabilization of the Dispersed System of Halloysite Nanotubes for Silicate Constructional Material
Authors: Lukuttsova Natalia , Golovin Sergey , Zolotukhina Natalia , Sycheva Olga
Published: October 2021

The stabilization of the dispersed system of halloysite nanotubes (HN) obtained by ultrasonic treatment (UST) in the aqueous medium of the stabilizers of sodium polynaphthalene methylene sulfonate stabilizers (S-3) and a synthetic compound based on polycarboxylate ether (MG) is considered. The morphology of halloysite is studied. Various mechanisms of aggregate stability connected with the spatial obstacles to aggregation due to the action of electrostatic, adsorption-solvate, and structural-mechanical stabilization factors are established. Three variants of introducing S-3 and MG stabilizers into the dispersed system of halloysite nanotubes are considered. It has been found that the most preferred method is the one with the stabilizer added in two steps. In this variant halloysite nanotubes are of minimum size and with maximum specific surface area. The maximum ζ-potential values of 52.9 mV and 43.8 mV are obtained for the dispersed system stabilized with S-3.
Algorithm of Energy-Saving Control Over Hammers of Active Excavator Buckets
Authors: Liberman Yako , Letnev Konstantin , Gorbunova Lyubov
Published: October 2021

The article considers the operation of excavators designed to mine hard or frozen soils. To reduce significant energy consumption, which characterizes the process, active buckets equipped with special hammers are used. Minimizing the energy consumption of such buckets can be achieved by optimally controlling their operating modes. Expressions for the energy consumed by a hammer, characteristics of its head, operating modes, soil are derived, with the minimum of the energy estimated. On the basis of those expressions, an algorithm of energy-saving control over hammers of active excavator buckets is formed and described. It determines the corresponding speed of impact of the hammer head on the soil which can be supplied to the hammer control system in the form of a command signal. The combination of all speeds when digging a track will provide the required performance of the excavator, with each speed set to the minimum, from the viewpoint of optimizing the energy consumption, necessary for the work of the hammer.
Theoretical Studies of Bounce in Rod-Type Microswitches
Authors: Lyuminarskaya E.S.
Published: October 2021

To improve reliability of microswitches, it is necessary to carry out theoretical studies of the switching process both at the moment of switching and at the moment of bouncing. The article presents a dynamic model of microswitches with elastic rod elements, which allows at the design stage to evaluate such basic performance characteristics as response time and contact bounce time. The proposed technique is based on representation of the solution to the differential equation of vibrations of an elastic element in the form of a linear combination of eigenforms and the application of the Bubnov-Galerkin method. Theoretical studies of bounce in a rod microswitch are carried out. It is shown that breakdown precursors of the spacer spring are an increase in the switching time and the time of the first separation in case of bouncing.
Left Frontal Lobe Tumor-Induced Intraoperative Premature Ventricular Beats
Authors: Bithal Parmod K. , Jan Ravees , Kumar Bharani , Rahman Insha ur
Published: October 2021

In the absence of cardiac pathology, premature ventricular contractions (PVCs) in neurosurgical patients frequently accompany subarachnoid hemorrhage, intracerebral hemorrhage, traumatic brain injury, or raised intracranial pressure. PVCs detected during preanesthesia assessment prompts detailed cardiac evaluation. Our 57-year-old patient, a case of left frontal meningioma, with controlled hypertension, diabetes and hypothyroidism, had normal preoperative ECG and potassium. However, immediately on anesthesia induction, she developed multiple refractory to treatment PVCs but with normal blood pressure. Anesthesia, which was maintained with sevoflurane and fentanyl, was deepened to exclude light anesthesia as the cause, without useful outcome. Two lignocaine boluses (100 mg each), followed by its infusion, also proved ineffective. Her blood gases and potassium, checked twice, were normal. Throughout, her hemodynamics remained stable. As soon as tumor was removed, the PVCs disappeared not to return. Her postoperative recovery was uneventful with normal ECG.
Effect of Beach-Chair Position on Cerebral Blood Flow in Patients Undergoing Shoulder Surgery—A Preliminary Observational Study
Authors: Antony Jesudoss , Singh Georgene , Yadav Bijesh , Abraham Melvin A. , George Sajan P.
Published: October 2021

Background Hypotension and cerebral hypoperfusion, commonly encountered in beach-chair position under general anesthesia, carry the risk of neurologic complications. There is a paucity of data on monitoring cerebral perfusion. Our objective was to compare the mean arterial pressure (MAP) and middle cerebral artery velocity (Vmca) in the supine and beach-chair position and estimate its correlation during hypotension.

Materials and Methods Twenty ASA class I and II patients undergoing elective shoulder surgery in beach-chair position were included in the study. MAP was measured invasively with the pressure transducer leveled to the phlebostatic axis. Vmca was measured with a 2 MHz transcranial Doppler (TCD) probe through the temporal window. Both MAP and Vmca were measured at baseline after anesthetic induction in the supine position (BL), on assuming the beach-chair position (AP), at steady-state hemodynamics in beach-chair position (P1), whenever there was a drop in MAP > 20% (P2), and on the restoration of MAP (P3).

Results A mean decrease in MAP and Vmca by 24.76% and 27.96%, respectively, from supine to beach-chair position with a significant linear correlation between MAP and Vmca along with a Pearsons' coefficient of 0.77 was seen. A change in MAP of 1 mm of Hg resulted in a change in Vmca by 0.53 cm/sec (p < 0.05).

Conclusion A significant decrease in MAP and Vmca was observed in the beach-chair position. TCD could be used as a point-of-care noninvasive technique to reliably assess cerebral perfusion.
Decoding the Onset of Intraoperative Normal Pressure Perfusion Breakthrough with Near-Infrared Spectroscopy and Jugular Venous Oxygen Saturation Catheter in a Case of Arteriovenous Malformation Surgery
Authors: Thakkar Keta , Thomas Jithumol T. , Hrishi Ajay P. , Sethuraman Manikandan
Published: October 2021

Multimodal monitoring can be a useful tool to design an appropriate anesthesia technique in the intraoperative period during the surgical excision of an intracerebral arteriovenous malformation (AVM). Intraoperatively, hyperperfusion syndrome can be attributed to causes like insufficient blood pressure control, occlusion of venous drainage before complete resection of arterial feeders, or inadequate hemostatic control of distended capillaries receiving arterial flow. We would like to highlight the potential role of near-infrared spectroscopy and jugular venous oxygen saturation catheter in detection of intraoperative normal perfusion pressure breakthrough and take necessary measures to prevent further insult with the help of this case report.
Effect of Therapeutic Plasma Exchange on Plasma Constituents in Neurointensive Care Unit Patients: A Retrospective Study
Authors: Srinivas Deepti , Sriganesh Kamath , Chakrabarti Dhritiman , Venkateswaran Pavithra
Published: October 2021

Purpose Plasma exchange is one of the recommended therapeutic procedures for autoimmune neurological conditions and involves removal of plasma over multiple sessions for exclusion of autoantibodies responsible for the disease process. This study aimed to evaluate the changes in the concentration of plasma constituents with five cycles of alternate day therapeutic plasma exchange (TPE), identify contributing factors for hypoproteinemia, and examine its impact on clinical outcomes.

Methods This was a single-center, retrospective cohort study involving patients with autoimmune neurological diseases who underwent at least five cycles of TPE in the neurointensive care unit (NICU). Data regarding plasma protein concentrations, serum electrolytes, fluid input/output before and after every TPE cycle and clinical outcomes in terms of duration of ventilation, and NICU and hospital stay were collected from the medical records over a 1-year period.

Results The levels of plasma proteins (total protein, albumin and globulin) (p < 0.001), sodium (p < 0.001), calcium (p < 0.001), and hemoglobin (p = 0.002) declined significantly after TPE. Difference in plasma protein levels before and after TPE did not correlate with durations of mechanical ventilation and hospital and NICU stay. Difference in total protein and globulin correlated negatively with fluid balance and positively with daily protein intake (p < 0.05 for both).

Conclusion A significant decrease in plasma proteins and other plasma constituents is seen with TPE. Changes in plasma proteins are related to hemodilution and protein intake. Decrease in plasma proteins did not affect duration of hospital or NICU stay and duration of mechanical ventilation.
Rare Case of Left Ventricular Thrombus Postmyocardial Infarction for Emergency Decompressive Craniectomy
Authors: Arikrishnan Thirumurugan , Chakravarthy Deepak , Uthaman Duraiyarassu , Srinivasan Gnanasekaran
Published: October 2021

Left ventricular (LV) thrombus formation is a notorious complication encountered in postmyocardial infarction patients. Such cases, when coming for noncardiac surgery, put the patient at greater risk of embolic events. Anesthesiologists play a pivotal role in the management of such rare and difficult cases. There is sparse evidence on management of such cases for noncardiac surgery. Hence, we would like to share our experience of a young patient with LV thrombus posted for left decompressive craniectomy.
Anticoagulation after Spontaneous Intraparenchymal Hemorrhage in Patients with Mechanical Heart Valves and Concomitant Atrial Fibrillation
Authors: Kang Jennifer H. , James Michael L. , Gibson Allison , Inamullah Ovais , Sherrill Gary Clay , Lutz Michael W. , Swisher Christa B.
Published: October 2021

Aim Patients with mechanical heart valves and coexisting atrial fibrillation (AFib-MHV) who suffer an intraparenchymal hemorrhage (IPH, defined as bleeding solely within the brain parenchyma and/or ventricle) are at a high risk of thromboembolism without anticoagulation. Data are lacking regarding the safety of early re-initiation of anticoagulation in these patients.

Patients and Methods We performed a descriptive, single-institution retrospective analysis of patients with AFib-MHV who suffered a non-traumatic, supratentorial IPH between July 2013 and June 2017. We analyzed the patients and IPH characteristics, anticoagulation and antiplatelet use, the occurrence of thrombotic and hemorrhage complications, and discharge disposition. We described the timing of initiation of anticoagulation and outcomes after IPH while in-patient.

Results Six patients with AFib-MHV suffered a spontaneous IPH. Four were initiated on anticoagulation prior to discharge, of whom two were initiated within 3 days post-hemorrhage. These patients suffered no bleeding complications and were discharged home with a modified Rankin Scale of 1.

Conclusion Patients with AFib-MHV who suffer a spontaneous IPH are a rare population to study. Further studies to guide the management of restarting anticoagulation in this select population are warranted.
The Knowledge, Attitude, and Behavior of Hospitalized Patients' Families in the Effort to Prevent COVID-19
Authors: Indraswari Anies Dewi Wirati , Aziz Abdul , Surboyo Meircurius Dwi Condro
Published: October 2021

Introduction The coronavirus disease-2019 (COVID-19) pandemic has also hit Indonesia. Until September 2020, cases continued to increase with the highest number in Jakarta. The right behavior needs to be followed to prevent COVID-19; this aspect has a strong relationship with knowledge and attitude. This study aimed to analyze the relationship between the knowledge, attitudes, and behavior of hospitalized patients' families in Fatmawati Hospital, Jakarta, in an effort to prevent COVID-19.

Materials and Methods A cross-sectional study was conducted on 300 respondents using a self-administered questionnaire to assess their knowledge, attitude, and behavior about COVID-19. The relationship between knowledge, attitude, and behavior was analyzed using the chi-square test with p < 0.05.

Results Most of the participants responded to the questionnaire showing a good knowledge, attitude, and behavior related to the efforts to prevent COVID-19. No relationship was present between knowledge, attitude, and behavior in an effort to prevent COVID-19 (p = 0.414 and p = 0.165).

Conclusion The hospitalized patients' families exhibited an adequate level of knowledge, attitude, and preventive behaviors toward COVID-19.
A Comparative Study on the Knowledge, Attitude, and Perception toward Hazardous Medical Waste Produced at Home in a Coastal City of Karnataka, India
Authors: Narayan Prajna , Jacob Ankeeta Menona , Shetty Pranav , Singh Preethika
Published: October 2021

Introduction Hazardous healthcare waste produced at home contributes to approximately 0.5% of biomedical waste, and although potentially infectious, is often discarded with other domestic wastes. The study aimed to quantify and compare types and patterns of biomedical waste generated in homes and to assess the knowledge, attitude, and practices regarding biomedical waste among selected urban and rural households in the coastal area of Mangalore city in Karnataka.

Methods A cross-sectional study was conducted in households consisting of rural and urban field practice areas of a tertiary care hospital in coastal Karnataka from November 2017 to February 2018. A pretested semi-structured questionnaire on knowledge, attitude, and practice regarding healthcare waste generated at home was assessed. Qualitative variables of the waste segregation practice, types of biomedical waste, the knowledge, perception, and attitude to practices regarding biomedical waste were expressed in percentages proportions and analyzed using SPSS v.20.

Results Baby diapers were the most common hazardous waste. The number of baby diapers produced daily in rural and urban areas was 32 (42.7%) and 64 (85.3%), respectively. The urban households had better knowledge of possible hazardous healthcare waste at home, 28 (37.33%) compared with 7 (9.3%) in rural households. Seventy-one (94.7%) urban and 49 (65.3%) rural households had a favorable attitude toward the disposal of hazardous domestic biomedical waste.

Conclusion The knowledge, attitudes, and practices regarding hazardous healthcare waste produced at the household level were better among urban households compared with rural households.
Transcutaneous Electrical Nerve Stimulation: A Review of Dental Applications
Authors: Pandita Vaibhav , Ajila Vidya , Babu G. Subhas , Hegde Shruthi , Asan Mohamed Faizal
Published: October 2021

Transcutaneous electrical nerve stimulation or TENS is a nonpharmacologic method that is used to alleviate pain from various acute and chronic conditions. TENS works through activation of descending inhibitory neurons of the central nervous system. In dentistry, TENS has applications for pain reduction in temporomandibular disorders and postherpetic neuralgia. It has also been studied for its role in increasing salivary secretion in subjects with xerostomia and as a local anesthetic agent in pediatric dentistry. Its wide applications in the orofacial region make it an important treatment modality. The purpose of the present review was to describe the general principles and its applications in dentistry along with its indications, advantages, and disadvantages. A web-based search was conducted using the keywords “transcutaneous electrical nerve stimulation,” “temporomandibular joint,” “TENS,” “TMJ,” “orofacial pain,” and “Management.” The manuscripts thus obtained were evaluated and used for compiling the present narrative review. The present review focuses on the mechanism of action, applications, and effectiveness of TENS in the management of diseases of the maxillofacial region.
Experiences of Registered Nurses in the Care of COVID-19 Patients: A Phenomenological Study
Authors: Salina Sunil , Leena K.C.
Published: October 2021

Introduction Coronavirus disease 2019 (COVID-19) is the infectious disease caused by the most recently discovered coronavirus. This new virus and disease were unknown before the outbreak began in Wuhan, China, in December 2019. COVID-19 is now a pandemic affecting many countries globally. The aim of this study was to examine the lived experiences of staff nurses who are involved in care of COVID-19 patients during COVID-19 outbreak in Kerala.

Methods Qualitative phenomenological approach was used in this study. Data was gathered from six registered nurses through telephonic interview and video call. Moustakas's structured method of inductive data analysis was used in the study.

Results Three themes were evolved from the current study. They are challenging profession, balancing profession with family, and from uncertainty to satisfaction.

Discussion Findings drew from the current study highlight ever seen areas in health industry. The health workers are the major workforce in any epidemic outbreak. Concern to their health needs to be one of the higher priorities. It is ideal to talk about infection control and use of personal protective equipment. But the practical implication needs to be further explored in connection with infection control.
Impacted Ring in the Penis: A Crisis Rescued by Plier
Authors: Chauhan Sanjeev , Rana Kirti , Kumar Manjeet , Raina Pamposh
Published: October 2021

A trapped penile ring is a urological emergency rarely seen. An impacted ring in penis is a real emergency uncommonly faced by a urologist. Emergent removal of the penile ring is indicated to prevent gangrene and damage to the penis. The insertion of these rings for autoerotic purposes is not uncommon. However, this can lead to impacted, stuck articles, rings in the penis. These patients present with symptoms ranging from mild penile pain, swelling to gangrenous changes in the penis. The removal of ring constricting penis is a penile-saving procedure. We describe a patient with a stuck ring in the penis and the technique of removal of the impacted penile ring by a household device plier. In case of emergency, the pliers are a useful tool for removing a strangulating penile ring
Influence of temperature variation on the electrical conductivity of zigzag carbon nanotubes under homogeneous axial dc field
Authors: Amekpewu M. , Mensah S. Y. , Musah R. , Abukari S. S. , Dompreh K. A. , Mensah N. G. , Kuwonu M.
Published: October 2021

We present theoretical framework investigations of the influence of temperature variation on the electrical conductivity of zigzag carbon nanotubes (CNTs) under the applied homogeneous axial dc field. This study was done semiclassically by solving Boltzmann transport equation to derive the current density of zigzag CNT as a function of homogenous axial dc field and temperature. Plots of the normalized current density versus homogeneous dc field applied along the axis of semiconducting zigzag CNTs as room temperature increases from 293 to 299 K revealed a significant increase in electrical conductivity, whereas in metallic zigzag CNTs, almost constant or a negligible decrease in electrical conductivity is observed. The study predicts semiconducting zigzag CNT as a potential material for temperature sensors since it exhibits a faster response and a substantially higher sensitivity to room temperature changes than the metallic counterpart. The electrical conductivity of metallic zigzag CNTs increases immensely as the temperature is reduced to a very low value which could probably lead to a potential superconductivity property that usually occurs at very low temperatures. These potential temperature sensors and superconductors of nanomaterial have vast applications in current-day science and technology.
A hybrid coupler for directing quantum light emission with high radiative Purcell enhancement to a dielectric metasurface lens
Authors: Yang Frank , Jha Pankaj Kumar , Akbari Hamidreza , Bauser Haley C. , Atwater Harry A.
Published: October 2021

Quantum photonic technologies such as quantum sensing, metrology, and simulation could be transformatively enabled by the availability of integrated single photon sources with high radiative rates and photon collection efficiencies. We address these challenges for quantum emitters formed from color center defect sites such as those in hexagonal boron nitride, which are promising candidates as single photon sources due to their bright, stable, polarized, and room temperature emission. We report design of a nanophotonic coupler from color center quantum emitters to a dielectric metasurface lens. The coupler is comprised of a hybrid plasmonic–dielectric resonator that achieves a large radiative Purcell enhancement and partial control of far-field radiation. We report radiative Purcell factors up to 285 and photon collection efficiencies up to 89% for a lossless metasurface, applying a continuous hyperboloidal phase-front. Our hybrid plasmonic–dielectric coupler interfacing two nanophotonic elements is a compound optical element, analogous to those found in microscope objective lenses, which combine multiple optical functions into a single component for improved performance.
Design of dual-band single-layer metasurfaces for millimeter-wave 5G communication systems
Authors: Hwang In-June , Yun Dal-Jae , Park Jeong-Il , Hong Young-Pyo , Lee In-Ho
Published: October 2021

We propose dual-band filters made from a single-layer metasurface for operating on the 28 and 39 GHz bands in mm-wave fifth generation (5G) communication systems. We use the conformational space annealing method, a global optimization technique, and test the usefulness of dual-band metasurfaces through design, fabrication, and measurement with 2916 square-shaped pixels per unit cell defined on a single layer. Each square-shaped pixel has only two states: either filled with metal or free of metal. We were able to obtain transmissive metasurfaces capable of performing three different functions, bandpass/bandpass, bandpass/band-stop, and band-stop/bandpass, by setting three different objective functions applicable to 5G communications. The designed filters have insertion loss of less than 3 dB in the passband region and greater than 20 dB in the stop band region. As a proof-of-concept, we fabricate very thin (50 μm) single-layer metasurfaces etched on only one side of a single dielectric substrate combined with a 5G antenna array to demonstrate high-frequency-selectivity with dual-band operation experimentally.
Domain switching dynamics in relaxor ferroelectric Pb(Mg1/3Nb2/3)O3–PbTiO3 revealed by time-resolved high-voltage electron microscopy
Authors: Sato Kazuhisa , Asakura Naoya
Published: October 2021

Ferroelectric domain dynamics in Pb(Mg1/3Nb2/3)O3–0.3PbTiO3 single crystals have been studied by in situ biasing high-voltage transmission electron microscopy with a direct electron detection camera. We have achieved time-resolved recording of polarization switching in real space on a 2.5 ms time scale. The reversible response of micrometer-scale domains was observed by applying an electric field of 1 kV/mm. Detailed analyses on smaller sized domains 100–500 nm in size revealed that the domain switching initiated at a corner of a rectangular domain and propagated inward rapidly. The switching proceeded within 60 ms and the maximum switching rate, as fast as 6–8 μm/s, was observed. The domain switching kinetics was classified as two-dimensional nucleation and growth mode based on the Kolmogolov–Avrami–Ishibashi model.
Single-shot quantitative phase imaging with polarization differential interference contrast
Authors: Strassberg Mark , Shevtsova Yana , Kamel Domenick , Wagoner-Oshima Kai , Zhong Hualin , Xu Min
Published: October 2021

We present single-shot quantitative phase imaging with polarization differential interference contrast (PDIC) for a differential interference contrast microscope which records the unfiltered Stokes vector of the differential interference pattern with a polarization camera. PDIC enables high spatial resolution phase imaging in real-time, applicable to either absorptive or transparent samples and integrates simply with epi-fluorescence imaging. An algorithm with total variation regularization is further introduced to solve the quantitative phase map from the partial derivative along one single axis, improving the accuracy and the image quality from the Fourier transform solution. After quantifying the accuracy of PDIC phase imaging with numerical simulations and phantom measurements, we demonstrate the biomedical applications by imaging the quantitative phase of both stained and unstained histological tissue sections and visualizing the fission yeast Schizosaccharomyces pombe's cytokinesis.
Phase-field modelling of transformation pathways and microstructural evolution in multi-principal element alloys
Authors: Kadirvel Kamalnath , Kloenne Zachary , Jensen Jacob K. , Fraser Hamish , Wang Yunzhi
Published: October 2021

The recently developed refractory multi-principle element alloy, AlMo0.5NbTa0.5TiZr, shows an interesting microstructure with cuboidal precipitates of a disordered phase (β, bcc) coherently embedded in an ordered phase (β′, B2) matrix, unlike the conventional Ni-based superalloys where the ordered phase (γ′, L12) is the precipitate phase and the disordered phase (γ, fcc) is the matrix phase. It becomes critical to understand the phase transformation pathway (PTP) leading to this microstructure in order to tailor the microstructure for specific engineering applications. In this study, we first propose a possible PTP leading to the microstructure and employ the phase-field method to simulate microstructural evolution along the PTP. We then explore possible PTPs and materials parameters that lead to an inverted microstructure with the ordered phase being the precipitate phase and the disordered phase being the matrix phase, a microstructure similar to those observed in Ni-based superalloys. We find that in order to maintain the precipitates as highly discrete particles along these PTPs, the volume fraction of the precipitate phase needs to be smaller than that of the matrix phase and the elastic stiffness of the precipitate phase should be higher than that of the matrix phase.
Learning intermolecular forces at liquid–vapor interfaces
Authors: Niblett Samuel P. , Galib Mirza , Limmer David T.
Published: October 2021

By adopting a perspective informed by contemporary liquid-state theory, we consider how to train an artificial neural network potential to describe inhomogeneous, disordered systems. We find that neural network potentials based on local representations of atomic environments are capable of describing some properties of liquid–vapor interfaces but typically fail for properties that depend on unbalanced long-ranged interactions that build up in the presence of broken translation symmetry. These same interactions cancel in the translationally invariant bulk, allowing local neural network potentials to describe bulk properties correctly. By incorporating explicit models of the slowly varying long-ranged interactions and training neural networks only on the short-ranged components, we can arrive at potentials that robustly recover interfacial properties. We find that local neural network models can sometimes approximate a local molecular field potential to correct for the truncated interactions, but this behavior is variable and hard to learn. Generally, we find that models with explicit electrostatics are easier to train and have higher accuracy. We demonstrate this perspective in a simple model of an asymmetric dipolar fluid, where the exact long-ranged interaction is known, and in an ab initio water model, where it is approximated.
Transparent β-Si3N4 and γ-Si3N4 compacts synthesized with mixed-size precursor under high pressure and high temperature
Authors: Ma Shuailing , Zhao Yongsheng , Tang Ruilian , Yang Bin , Tao Qiang , Li Yan , Cheng Jiaen , Wang Yu , Cui Tian , Zhu Pinwen
Published: October 2021

Transparent polycrystalline ceramics exhibit improved mechanical and optical properties. However, synthesizing transparent ceramics without additives is nontrivial. Herein, we report the synthesis of two transparent ceramics (β-Si3N4 and γ-Si3N4) under high pressure and high temperature from a pure Si3N4 precursor with nano-/micro-dual grain sizes. Synthesized β-Si3N4 exhibited a significantly enhanced Vickers hardness reaching 24.2 GPa (at 10 N load) when transparency was achieved. Transparent nano-grained γ-Si3N4 exhibited a Vickers hardness of 37.3 GPa. These are the highest hardness values reported for these two phases at a 10 N load. Density and microstructure measurements suggest that the hardness and transparency of the specimens correlate with both the grain size and porosity/density. The negligible amount of pores accounts for the superior optical transparency and high hardness of two Si3N4 allotropes. As higher pressures can effectively suppress grain growth and minimize pores between grains, high-pressure sintering is demonstrated as an effective way to realize highly dense transparent ceramics.
Relative intensity noise and intrinsic properties of RF mounted interband cascade laser
Authors: Didier P. , Spitz O. , Cerutti L. , Diaz-Thomas D. A. , Baranov A. N. , Carras M. , Grillot F.
Published: October 2021

Interband cascade lasers are semiconductor lasers emitting in the mid-infrared domain but relying on interband transitions, contrary to their intersubband counterparts, quantum cascade lasers. Our experimental study of the relative intensity noise in a multi-mode interband cascade laser at 4.1 μm shows that the room-temperature structure exhibits a relaxation frequency in the GHz range. We demonstrate that, far above the threshold current, the relaxation frequency increases with the bias current, and our simulations are in good agreement with our experimental efforts. Fitting of the relative intensity noise resonances gives access to several intrinsic parameters of the interband cascade laser under study such as differential gain, compression gain, and K-factor. This study is a clear step for understanding dynamics interplays in interband cascade laser structures, which means understanding the non-linear and modulation bandwidth limitations of such lasers.
Cascaded Ni hard mask to create chlorine-based ICP dry etched deep mesas for high-power devices
Authors: Ahmad Habib , Engel Zachary , Zia Muneeb , Weidenbach Alex S , Matthews Christopher M , Zivasatienraj Bill , Bakir Muhannad S , Doolittle W Alan
Published: October 2021

A highly selective cascaded Ni hard mask without stress and film damage issues suitable for the formation of deep vertical mesas for high-power devices is presented. A Cl2/BCl3/Ar inductively coupled plasma dry etch was used to investigate the effect of photoresist, and patterned Ni hard masks applied via four different methods on the etch rate of GaN, and mask selectivity. Strain in the e-beam only deposited Ni films produced low yield due to poor adhesion. Electroplated Ni showed rough mask morphology. Sputtered Ni left damage/chemically reacted layers on the GaN under the mask. A cascaded 50 nm e-beam evaporated Ni followed by 2 µm of sputtered Ni mask method improved the yield to 100%, achieved high selectivity and retained an undamaged GaN surface morphology. The cascaded Ni hard mask successfully achieved GaN mesas up to 13 µm. The dry etching rates of the photoresist, GaN and Ni masks were 250, 275 and 13 nm min−1, respectively giving an etch selectivity of the GaN/Ni hard mask of ∼20, much higher than the etch selectivity of 1.1 for the photoresist. Furthermore, yield of the cascaded Ni hard mask was 100% making it suitable for commercial high-power electronics.
Sustainable internal transport barrier discharge at KSTAR
Authors: Chung J. , Hahn S.-H. , Han H. , Kang J. , Kim H.S. , Jeon Y.M. , Ko J. , Lee K.D. , Ko W.H. , Seo S.H. , Lee J.H. , Juhn J.-W. , Lee M.W. , Woo M.H. , Cho Y.W. , Yoon S.W.
Published: October 2021

We explore the inboard-limited internal transport barrier (ITB) as an alternative advanced operation scenario for KSTAR. This paper presents in detail the progress of the ITB experiment at KSTAR. In an earlier study, the ITB formed in both ion and electron thermal channels, and an early neutral-beam injection (NBI) power of over 4 to 5 MW under a limited L-mode was crucial to ITB access. In the present study, we access the ITB experimentally with about 3 MW of NBI power by using the upper single null (USN), which is an unfavorable H-mode condition with a higher L–H power threshold. Finding an ITB access condition with a lower heating power should allow for a more efficient control of the heat flux and for maintaining stable plasma performance. The key control parameters of the experiment are the vertical position and the location of outboard striking point of the plasma. The shape-control attempts to divert the plasma to a vertically shifted USN with a marginal touch of the inboard limiter so that the plasma can remain in the L-mode at the boundary, while the striking-point control maintains the ITB performance for a longer period of time.
Feasibility study of tokamak, helical and laser reactors as affordable fusion volumetric neutron sources
Authors: Goto T. , Tanaka T. , Tamura H. , Miyazawa J. , Iwamoto A. , Yanagi N. , Fujita T. , Kodama R. , Mori Y.
Published: October 2021

The applicability of tokamak, helical and laser fusion reactors as a volumetric fusion neutron source has been examined using the systems codes that have been utilised for the conceptual design of DEMO and commercial reactors in Japan. This study has clarified the characteristics of reactor-based volumetric neutron sources that can be designed based on the current physics and engineering basis with a reasonable running cost (∼5B Yen/year). Although the achievable neutron flux is 2–3 orders lower than that of accelerator driven neutron sources, tokamak and helical neutron sources can provide a much larger irradiation area for the test of large components. Laser neutron sources have both high operability and tritium breeding capacity. These reactor-based neutron sources also serve as an integrated test bed of the entire reactor system.
Quasiparticle energies and optical response of RbTiOPO4 and KTiOAsO4
Authors: Neufeld S , Schindlmayr Arno , Schmidt W G
Published: October 2021

Many-body perturbation theory based on density-functional theory calculations is used to determine the quasiparticle band structures and the dielectric functions of the isomorphic ferroelectrics rubidium titanyl phosphate (RbTiOPO4) and potassium titanyl arsenide (KTiOAsO4). Self-energy corrections of more than 2 eV are found to widen the transport band gaps of both materials considerably to 5.3 and 5.2 eV, respectively. At the same time, both materials are characterized by strong exciton binding energies of 1.4 and 1.5 eV, respectively. The solution of the Bethe–Salpeter equation based on the quasiparticle energies results in onsets of the optical absorption within the range of the measured data.
Hessian-based toolbox for reliable and interpretable machine learning in physics
Authors: Dawid Anna , Huembeli Patrick , Tomza Michał , Lewenstein Maciej , Dauphin Alexandre
Published: October 2021

Machine learning (ML) techniques applied to quantum many-body physics have emerged as a new research field. While the numerical power of this approach is undeniable, the most expressive ML algorithms, such as neural networks, are black boxes: The user does neither know the logic behind the model predictions nor the uncertainty of the model predictions. In this work, we present a toolbox for interpretability and reliability, agnostic of the model architecture. In particular, it provides a notion of the influence of the input data on the prediction at a given test point, an estimation of the uncertainty of the model predictions, and an extrapolation score for the model predictions. Such a toolbox only requires a single computation of the Hessian of the training loss function. Our work opens the road to the systematic use of interpretability and reliability methods in ML applied to physics and, more generally, science.
Low-temperature synthesis of high-quality graphene by controlling the carbon-hydrogen ratio of the precursor
Authors: Huang Jian-Zhi , Ni I-Chih , Hsu Yun-Hsuan , Li Shu-Wei , Chan Yu-Chen , Yang Shin-Yi , Lee Ming-Han , Shue Shau-Lin , Chen Mei-Hsin , Wu Chih-I
Published: October 2021

A furnace-free inductively coupled plasma chemical vapor deposition (ICP-PECVD) system, which does not require sample heating, was used to grow graphene at a temperature below 300 °C. This studies have found that under low-temperature PECVD growth conditions, liquid precursors are more suitable for preparing low-temperature graphene precursors than gaseous precursors.​​​​ Hence, benzene is used as a carbon precursor to obtain a sheet resistance of approximately 1.24 kΩ sq−1. In this research, it was discovered that the carbon-hydrogen ratio of the precursor molecule is an important factor while using PECVD to grow graphene. This factor affects the quality of graphene and the sheet resistance value —when the carbon–hydrogen ratio for the precursor molecule is 1:1, graphene has the high quality and lowest sheet resistance; when it is less than 1:2, the graphene that cannot be deposited has the worst quality and sheet resistance. Furthermore, we found that methane, a precursor often used to deposit graphene, will etch graphene under low-temperature conditions, and that acetylene can be used as a precursor to deposit graphene. It was further proven that the carbon–hydrogen ratio of the precursor molecules in the PECVD process caused the reduction in the graphene temperature.