bluuebunny/crossref_metadata_2025 huggingface dataset:
Surgical Indication Optimization of Brain Metastases Based on the Evolutionary Analysis of Karnofsky Performance Status
Authors: Rasmussen Jorge , Ajler Pablo , Massa Daniela , Plou Pedro , Baccanelli Matteo , Yampolsky Claudio
Published: January 2021

Background and Objective Surgical resection of brain metastases (BM) offers the highest rates of local control and survival; however, it is reserved for patients with good functional status. In particular, the presence of BM tends to oversize the detriment of the overall functional status, causing neurologic deterioration, potentially reversible following symptomatic pharmacological treatment. Thus, a timely indication of surgical resection may be dismissed. We propose to identify and quantify these variations in the functional status of patients with symptomatic BM to optimize the indication of surgical resection.

Patients and Methods Historic, retrospective cohort analysis of adult patients undergoing BM microsurgical resection, consecutively from January 2012 to May 2016, was conducted. The Karnofsky performance status (KPS) variation was recorded according to the symptomatic evolution of each patient at specific moments of the diagnostic–therapeutic algorithm. Finally, survival curves were delineated for the main identified factors.

Results One hundred and nineteen resection surgeries were performed. The median overall survival was 243 days, while on average it was 305.7 (95% confidence interval [CI]: 250.6–360.9) days. The indication of surgical resection of 10% of the symptomatic patients in our series (7.5% of overall) could have been initially rejected due to pharmacologically reversible neurologic impairment. Survival curves showed statistically significant differences when KPS was stratified following pharmacological symptomatic treatment (p < 0.0001), unlike when they were estimated at the time of BM diagnosis (p = 0.1128).

Conclusion The preoperative determination of the functional status by KPS as an evolutive parameter after the nononcologic symptomatic pharmacological treatment allowed us to optimize the surgical indication of patients with symptomatic BM.
Health Economic Aspects of Aneurysmal Subarachnoid Hemorrhage: Factors Determining First Year In-Hospital Treatment Expenses
Authors: Ridwan Sami , Urbach Horst , Greschus Susanne , Hagen Johanna Von , Esche Jonas , Boström Azize
Published: January 2021

Background Spontaneous aneurysmal subarachnoid hemorrhage (SAH) is a common neurosurgical emergency with a high case fatality rate. The clinical course of SAH generates high health economic expenses. Here we highlight possible cost-driving factors for in-hospital care expenses for the first year. Furthermore, results are compared with ischemic stroke treatment.

Methods One hundred and one patients with aneurysmal SAH treated in our hospital from 2007 through 2009 were included. The Hunt and Hess (HH) scale, World Federation of Neurosurgical Societies (WFNS) scale, Fisher Scale, and further outcome-relevant data were recorded. Expenses were calculated using the German fixed case rate classification system consisting of Diagnosis-Related Groups (DRG) and the Operation and Procedure catalogue (OPS). Overall acute length of stay (LOS) and LOS on the intensive care unit (ICU) were separately evaluated. Expenses were compared with formerly published first-year costs of ischemic stroke.

Results Fifty-four percent of the patients (median age 52 years, 69% females) received coiling and 46% clipping. Acute in-hospital treatment accounted for 82% of total in-hospital expenses, while consequential in-hospital treatment accounted only for 18%. Altogether, the total first-year in-hospital expenses for all patients were as high as €2,650,002, resulting in average SAH in-hospital treatment expenses of €26,238 per patient for the first year. Poor clinical condition on admission and longer stay in ICU are the main cost-driving factors. The impact of the aneurysm treatment method is debatable. Only a poor HH grade and longer ICU stay are independent cost-driving factors. SAH treatment expenses are far higher than treatment costs for ischemic stroke in the literature (€6,731 for first-year inpatient and €3,287 for outpatient treatment).

Conclusions Clinical condition and LOS determine in-hospital expenses after SAH. Aneurysmal SAH prevalently results in a relevant economic impact on the health system exceeding formerly published treatment expenses for ischemic stroke.
Comparison of the Minimally Invasive Tubular Transmuscular Approach with the Conventional Microsurgical Approach for Microsurgical Treatment of Lumbar Disk Herniation: A Prospective Randomized Study
Authors: Pintea Bogdan , Krämer Nadine , Müller Andreas , Geiger Matthias Florian , Podlogar Martin , Weber Patrick , Kristof Rudolf Andreas
Published: January 2021

Background The aim of this study is to compare the outcome of the minimally invasive transmuscular approach using a tubular retractor system (Metrx) with the conventional microsurgical standard approach (CM) for microsurgical treatment of lumbar disk herniation.

Methods This is a prospective randomized controlled study with a 1:1 distribution of patients in CM and Metrx study groups. Two hundred and twenty-seven (117 CM and 110 Metrx) patients were included. The primary outcome parameters are postoperative pain intensity reduction, length of hospitalization, postoperative quality of life, and daily life performance based on the standardized questionnaires: Visual Analog Scale (VAS), 36-Item Short Form Survey (SF-36), Oswestry Disability Index (ODI), and Prolo scores. The secondary outcome parameters are intraoperative variables: surgery duration, blood loss, and fluoroscopy dose.

Results There were no significant statistical differences in the primary outcome measures between the two groups with respect to postoperative pain relief (median VAS pre-op to 3 months post-op for sciatica: 9–2 [CM] vs. 8–2 [Metrx]; for lumbago: 7–2.5 [CM] vs. 6–3 [Metrx]), the length of hospitalization (median of 5 days), or the frequency of occupational reintegration after 3 months (59.1 vs. 60.7%).

Conclusion The microsurgical therapy of lumbar disk herniation via a Metrx approach is a safe and effective treatment option and is equivalent to the CM approach.
The Effects of Local Food-Based Enteral Nutrition to Improve Nutritional Status of Post-Stroke Patients
Authors: Setyopranoto Ismail , Susetyowati  , Lestari Lily Arsanti , Probosuseno  , Wijayanti Punik Mumpuni , Rochmah Mawaddah Ar
Published: January 2021

Objective We used local-based enteral formula for post-stroke patients to see its effects on the nutritional status.

Materials and Methods This is an experimental research with a pre- and post-test study design in post-stroke patients. Participants underwent clinical and laboratory examinations to assess their nutritional status before and after the enteral nutrition supplementation. The enteral formula preparation, containing arrowroot powder, cork fish, tempeh (fermented soybeans), nondairy creamer, and pumpkin, was performed in a nationally standardized Food Processing Technology Laboratory in Yogyakarta, Indonesia. The enteral formula was given twice a day for 3 consecutive weeks in addition to the patients’ daily meal.

Statistical Analysis Nutritional indices before and after enteral nutrition supplementation were analyzed using t-test. All statistical analyses were at 5% significance level.

Results Of the 22 post-stroke patients, we used the cutoff point of National Institutes of Health Stroke Scale ≥3 and Barthel Index <90 to represent dependency. Our findings showed significantly reduced mid-upper arm circumference and increased body mass index in independent post-stroke patients after the enteral nutrition supplementation. The tendency of increasing total cholesterol level should be carefully watched in dependent post-stroke patients.

Conclusion Local food-based enteral nutrition supplementation for 3 consecutive weeks in post-stroke patients may improve their nutritional status.
Migraine in Nursing Students—A Study from a Tertiary Care Center in South India
Authors: Menon Bindu , Remadevi Nikethana
Published: January 2021

Objective Nursing profession is subject to occupational stress, which can be a trigger for headaches. Our study aimed to study the prevalence of migraine, its characteristics, triggers, and relieving factors among nursing students in a tertiary care center.

Materials and Methods This study was performed in a super-specialty hospital in South India. A structured questionnaire captured data on the occurrence of headache, demographics, aura, triggering factors, relieving factors, and lifestyle habits. Results are presented in numbers and percentage.

Results A total of 20% of nursing students in the study had headache of which 85% had migraine. Weekly and daily attacks were reported in 12 and 4% students, respectively. Twenty-two percent had headache severity of more than 5 visual analogue scale. Most common accompanying symptoms were photophobia (80%), phonophobia (70%), nausea (75%), vomiting (71%), neck pain (25%), and vertigo (20%). Thirty-nine percent had auras. Ninety-five percent reported triggers with 70% students having more than one trigger. Sleep was the relieving factor in 69%, head massage in 50%, and relaxing from work in 48%.

Conclusion The most common type of primary headache in nurses in our study was migraine. More than three-fourths nurses reported triggers and relieving factors. Addressing these factors could help in managing migraines and help in improving the quality of life and increased work productivity of nurses.
Epidemiological Profiling and Trends of Primary Intracranial Tumors: A Hospital-Based Brain Tumor Registry from a Tertiary Care Center
Authors: Meel Mukta , Choudhary Nikita , Kumar Mukesh , Mathur Kusum
Published: January 2021

Background and Objectives Hospital-based cancer registry is an essential tool for augmentation of the standard of care, administration motive, and resource for population-based cancer registries. Here, we presented hospital-based brain tumor registry (HBBTR) to outline a comprehensive epidemiological data, both clinical and histopathological, as well as trends of central nervous system tumors. In addition, we compare this data with national brain tumor data as well as an international brain tumor registry.

Materials and Methods For the generation of this 7-year HBBTR data of all primary intracranial tumors operated, diagnosed, and registered at the Department of Pathology, Sawai ManSingh, between January 1, 2013 and December 31, 2019, was collected, analyzed, and compared with Tata Memorial Hospital, National Institute of Mental Health and Neurosciences, and Central Brain Tumor Registry of the United States.

Results A total of 3,526 patients were of primary intracranial tumors. Out of which, male patients were 1,982 (56.2%), while 1,544 (43.8%) were female patients. Maximum proportion of tumors was in fifth decade. Overall, pediatric and adult patients constituted of 15.5 and 84.5% of the cases, respectively. Among all primary intracranial tumors, meningiomas (20%) were most common followed by glioblastoma multiformat (18%) and least common were germ cell tumors (0.1%) followed by pineal tumors (0.3%). In pediatric cohort astrocytic tumors (30.1%) are most common followed by embryonal tumors (20.8%), while in adults meningiomas (23.1%) were most common followed by glioblastomas (20.3%). Our registry showed similar trends of tumors with national data as compared with international data in median age of presentation.

Conclusion This HBBTRs provide prevalence of primary intracranial tumors at a tertiary care center and could be a part of population-based registry.
Mannitol Dosing Error during Pre-neurosurgical Care of Head Injury: A Neurosurgical In-Hospital Survey from Ibadan, Nigeria
Authors: Adeleye Amos Olufemi , Oyemolade Toyin Ayofe , Malomo Toluyemi Adefolarin , Okere Oghenekevwe Efe
Published: January 2021

Objectives Inappropriate use of mannitol is a medical error seen frequently in pre-neurosurgical head injury (HI) care that may result in serious adverse effects. This study explored this medical error amongst HI patients in a Nigerian neurosurgery unit.

Methods We performed a cross-sectional analysis of a prospective cohort of HI patients who were administered mannitol by their initial non-neurosurgical health care givers before referral to our center over a 22-month period.

Statistical Analysis A statistical software was used for the analysis with which an α value of <0.05 was deemed clinically significant.

Results Seventy-one patients were recruited: 17 (23.9%) from private hospitals, 13 (18.3%) from primary health facilities (PHFs), 20 (28.2%) from secondary health facilities (SHFs), and 21 (29.6%) from tertiary health facilities (THFs). Thirteen patients (18.3%) had mild HI; 29 (40.8%) each had moderate and severe HI, respectively. Pupillary abnormalities were documented in five patients (7.04%) with severe HI and neurological deterioration in two with mild HI.

Mannitol administration was deemed appropriate in only 43.7% (31/71). Data on mannitol dosing in 60.6% (43/71) of the patients showed 8/43 (18.6%) receiving continuous 10% mannitol infusion. The remaining 35/43 received mannitol as a 20% solution but also showing dosing error in 62.9% (22/35): overdosing in 7/35 (20%), and nonbolus administration in 15/35 (42.9%). The distribution of the dosing error among the referring health facilities (all the 13 [100%] patients from private hospitals, 66.7% from PHF, 60% from SHF, and 45.5% from THF) showed a trend of better performance (p = 0.002) by the THFs.

Conclusion Mannitol use is apparently fraught with an understudied medical error in the pre-neurosurgical care of the head injured.
Bilaminate Synthetic Dermal Matrix versus Free Fascial Flaps: A Cost-Effectiveness Analysis for Full-Thickness Hand Reconstruction
Authors: Miller Travis J. , Lin Walter C. , Watt Andrew J. , Sheckter Clifford C.
Published: January 2021

Background Full-thickness injuries to the hand require durable soft tissue coverage to preserve tendon gliding and hand motion. We aim to investigate the cost effectiveness of hand resurfacing comparing free fascial flap reconstruction versus bilaminate synthetic dermal matrices.

Methods Cost effectiveness was modeled using decision tree analysis with the rollback method. Total active range of motion was modeled as the common outcome variable based on systematic literature review. Costing was performed from a payer perspective using national Medicare reimbursements. The willingness to pay threshold was determined by average worker's compensation for hand disability. Probabilistic sensitivity analysis was conducted for range of motion outcomes and the costs using 10,000 Monte Carlo simulations.

Results The average cost of free fascial flap reconstruction was $14,201.24 compared with $13,674.20 for Integra, yielding an incremental cost difference of $527.04. Incremental range of motion improvement was 18.0 degrees with free fascial flaps, yielding an incremental cost effectiveness ratio of $29.30/degree of motion. Assuming willingness to pay thresholds of $557.00/degree of motion, free-fascial flaps were highly cost effective. On probabilistic sensitivity analysis, free fascial flaps were dominant in 25.5% of simulations and cost effective in 32.1% of simulations. Thus, microsurgical reconstruction was the economically sound technique in 57.5% of scenarios.

Conclusion Free fascial flap reconstruction of complex hand wounds was marginally more expensive than synthetic dermal matrix and yielded incrementally better outcomes. Both dermal matrix and microsurgical techniques were cost effective in the base case and in sensitivity analysis. In choosing between dermal matrix and microsurgical reconstruction of complex hand wounds, neither technique has a clear economic advantage.
The geometrical analysis of localization error characteristic in stereo vision systems
Authors: Li Xing , Gao Shuang , Yang Yanqiang , Liang Jian
Published: January 2021

The parameters of a stereo camera directly determine the accuracy of a stereo vision positioning system. In this paper, the relationship between camera parameter error and positioning error is established by using the geometric analysis method with a clear physical meaning. The error models of the relative position error and camera resolution error of the stereo camera are established. The relative position error of the stereo camera is represented by the rotation and translation of the coordinate system, and the positioning error is derived from image coordinates through the pinhole camera model. For the camera resolution error, the two pixels of the stereo camera are projected into an octahedral uncertain region in space. We use geometric methods to derive the maximum size of the octahedron in the three-axis direction. The maximum size in the three-axis direction is used to evaluate the impact of camera resolution errors. The depth of field and angle of view are used to represent the measured area. The effects of resolution error and camera parameters on the measurement error of each axis are analyzed. Finally, a large number of simulations verified our conclusion. By comparing the effects of the magnitude of the error, we can conclude that the baseline and pixel size of the camera have a greater impact on the positioning accuracy.
Combining application of wavelet analysis and genetic algorithm in wind tunnel simulation of unidirectional natural wind field near a sand ground surface
Authors: Bo Zhang , Xiaosi Zhou , Yuxin Liu , Bin Yang , Yang Zhang
Published: January 2021

This study proposes a method for the approximate simulation of field gust in an atmospheric boundary layer wind tunnel driven by an axial fan. Wavelet analysis and genetic algorithm have been adopted to convert actual field gust data into a series of simplified and smooth control signals. One frequency converter is used to receive the signals via a programmable logic controller and change the fan speed correspondingly. Results show that the low-frequency energetic part of field gust on top of a saltation layer has been almost reproduced in the wind tunnel with energy fluctuations ±3.26% from the mean compared with the field data in terms of energy. The appropriate filter frequency for field gust velocity history is 1/32 Hz. A unidirectional natural wind field near a sand bed surface can be approximately simulated in the tunnel by adjusting carefully the roughness element arrangement. The time-averaged velocity profile of the simulated wind, which satisfies the logarithmic law, is nearly equivalent to the steady flow with the same average velocity.
Gate-based superconducting quantum computing
Authors: Kwon Sangil , Tomonaga Akiyoshi , Lakshmi Bhai Gopika , Devitt Simon J. , Tsai Jaw-Shen
Published: January 2021

In this Tutorial, we introduce basic conceptual elements to understand and build a gate-based superconducting quantum computing system.
Recommended Cross Sections for Electron–Indium Scattering
Authors: Hamilton K. R. , Zatsarinny O. , Bartschat K. , Rabasović M. S. , Šević D. , Marinković B. P. , Dujko S. , Atić J. , Fursa D. V. , Bray I. , McEachran R. P. , Blanco F. , García G. , Stokes P. W. , White R. D. , Jones D. B. , Campbell L. , Brunger M. J.
Published: January 2021

We report, over an extended energy range, recommended angle-integrated cross sections for elastic scattering, discrete inelastic scattering processes, and the total ionization cross section for electron scattering from atomic indium. In addition, from those angle-integrated cross sections, a grand total cross section is subsequently derived. To construct those recommended cross-section databases, results from original B-spline R-matrix, relativistic convergent close-coupling, and relativistic optical-potential computations are also presented here. Electron transport coefficients are subsequently calculated, using our recommended database, for reduced electric fields ranging from 0.01 Td to 10 000 Td using a multiterm solution of Boltzmann’s equation. To facilitate those simulations, a recommended elastic momentum transfer cross-section set is also constructed and presented here.
Understanding fundamental trade-offs in nanomechanical resonant sensors
Authors: Demir Alper
Published: January 2021

Nanomechanical resonators are used as high performance detectors in a variety of applications such as mass spectrometry and atomic force microscopy. Initial emphasis in nanomechanical resonant sensors based on tracking resonance frequency deviations was on increasing the sensitivity to the level of a single molecule, atom, and beyond. On the other hand, there are applications where the speed of detection is crucial, prompting recent works that emphasize sensing schemes with improved time resolution. Here, we first develop a general modeling framework and a comprehensive theory encompassing all resonance frequency tracking schemes currently in use. We then explore the fundamental trade-offs between accuracy and speed in three resonant sensor architectures, namely, the feedback-free open-loop approach, positive-feedback based self-sustaining oscillator, and negative-feedback based frequency-locked loop scheme. We comparatively analyze them in a unified manner, clarify some misconceptions and confusion that seem to exist in the literature, and unravel their speed vs accuracy characteristics.
New estimation of Zipf–Mandelbrot and Shannon entropies via refinements of Jensen’s inequality
Authors: Ahmad Khurshid , Adil Khan Muhammad , Khan Shahid , Ali Amjad , Chu Yu-Ming
Published: January 2021

Zipf–Mandelbrot and Shannon entropies are some basic and useful tools to quantify information about certain phenomena in various fields of science and technology, for example statistics, ecology, biology, and information theory. In this paper, we obtain some new bounds for generalized Shannon and Zipf–Mandelbrot entropies by using some specific refinements of Jensen’s inequality. Then, as a consequence of these bounds, we deduce some new bounds for Zipf–Mandelbrot and Shannon entropies. Finally, we demonstrate the sharpness of the proposed bounds through numerical experiments.
Magnetic measurement and analysis of c-type amorphous by an improved adjustable air gap tester
Authors: Li Yongjian , Wan Zhenyu , Sun He , Liu Huan
Published: January 2021

A novel magnetic properties tester is designed to accurately and conveniently change the air gap of the core, which can fix cores of various types. The dynamic magnetic characteristics of the amorphous core under sinusoidal excitation within 20 kHz is measured with different air gap lengths and magnetic flux density. It is found that in the case of the small air gap, the total loss decreases as the air gap increases. When the frequency is 20 kHz and the flux density is 0.1 T, the loss can even be reduced by 7%. This paper analyzes the experimental data and summarizes the influence of the air gap and magnetic flux density about the core loss. Besides, the influence of air gap on magnetic flux density distribution is illustrated and analyzed by the means of FEM (Finite Element Method). It is valuable for the design of high frequency transformer and inductor.
Adenovirus-vectored vaccine containing multidimensionally conserved parts of the HIV proteome is immunogenic in rhesus macaques
Authors: Murakowski Dariusz K. , Barton John P. , Peter Lauren , Chandrashekar Abishek , Bondzie Esther , Gao Ang , Barouch Dan H. , Chakraborty Arup K.
Published: January 2021

Significance

HIV is a highly mutable pathogen that can mutate to evade vaccine-induced immune responses, thus negating the vaccine’s protective effects. If mutations that evade immune responses incur a fitness penalty for the virus, other mutations can evolve to partially compensate for fitness loss. Accounting for such effects, we designed a single long peptide immunogen comprised of parts of HIV proteins wherein mutations would be difficult to evolve without fitness penalties for the virus. This designed immunogen was expressed in adenovirus vectors, which are in clinical development (e.g., for COVID-19). Monkeys immunized with our vaccine exhibited strong T-cell responses directed toward regions contained in our immunogen. This suggests that further exploration of this vaccine for use in humans is warranted.
Explosion analysis from images: Trinity and Beirut*
Authors: Díaz Jorge S.
Published: January 2021

Images of an explosion can be used to study some of its physical properties. After reviewing the key aspects of the method originally developed to study the first nuclear detonation and analyzing the Trinity blast data, the method is applied to the Beirut explosion of August 2020 by using images from videos posted online. The applicability of the method is discussed and the process of selection, extraction, and analysis of the data is presented. The estimate for the energy yield of the Beirut explosion is found to be

2
.

3

−
1.1

+
1.1

TJ or

0
.

6

−
0.3

+
0.3

kt of TNT equivalent. The result is consistent with others recently appeared in the literature using different methods. Notice that this article includes content that some readers may find distressing.
Progress in state-of-the-art technologies of Ga2O3devices
Authors: Wang Chenlu , Zhang Jincheng , Xu Shengrui , Zhang Chunfu , Feng Qian , Zhang Yachao , Ning Jing , Zhao Shenglei , Zhou Hong , Hao Yue
Published: January 2021

Gallium oxide (Ga2O3), an emerging ultra-wide-bandgap semiconductor, has the desirable properties of a large bandgap of 4.6–4.9 eV, an estimated critical breakdown field of 8 MV cm−1, decent electron mobility of 250 cm2V s−1and high theoretical Baliga figures of merit (BFOMs) of around 3000. Bolstered by their capability of an economical growth technique for high-quality bulk substrate,β-Ga2O3-based materials and devices have been highly sought after in recent years for power electronics and solar-blind ultraviolet photodetectors. This article reviews the most recent advances inβ-Ga2O3power device technologies. It will begins with a summary of the field and underlying semiconductor properties of Ga2O3, followed by a review of the growth methods of high-qualityβ-Ga2O3bulk substrates and epitaxial thin films. Then, brief perspectives on the advanced technologies and measurements in terms of ohmic contact and interface state are provided. Furthermore, some state-of-the-artβ-Ga2O3photoelectronic devices, power devices and radiofrequency devices with distinguished performance are fully described and discussed. Some solutions to alleviating challenging issues, including the difficulty in p-type doping, low thermal conductivity and low mobility, are also presented and explored.
Facile synthesis of β–Ga2O3 nanowires network for solar-blind ultraviolet photodetector
Authors: Zhang Miaomiao , Kang Shuai , Wang Liang , Zhang Kun , Wu Yutong , Feng Shuanglong , Lu Wenqiang
Published: January 2021

Gallium oxide (Ga2O3) has become a viable candidate for certain types of high-power devices due to its large energy bandgap of 4.9 eV, which has attracted widespread attention. In particular, Ga2O3 nanowire structures have more unique properties due to its larger specific surface area for the high performance solar-blind ultraviolet (UV) photodetectors. In this work, the ultrafine Ga2O3 nanowire network structure is obtained on the sapphire substrate with an Au catalyst by chemical vapor deposition method at 960 °C for 10 min. We can confirm that the growth of the nanowire follows the vapor–liquid–solid growth mechanism and is a β-type Ga2O3 crystal through the performance test results. A solar-blind UV photodetector based on the nanowires network shows an apparent response to solar-blind UV light and almost no response to 365 nm wavelength. Furthermore, the on–off ratio, light responsivity, and response time are also measured under a 254 nm wavelength UV light irradiation, respectively. This work provides a new preparation method to improve the performance of solar-blind UV photodetector.
Spatially and temporally non-uniform plasmas: microdischarges from the perspective of molecules in a packed bed plasma reactor
Authors: van ‘t Veer K , van Alphen S , Remy A , Gorbanev Y , De Geyter N , Snyders R , Reniers F , Bogaerts A
Published: January 2021

Dielectric barrier discharges (DBDs) typically operate in the filamentary regime and thus exhibit great spatial and temporal non-uniformity. In order to optimize DBDs for various applications, such as in plasma catalysis, more fundamental insight is needed. Here, we consider how the millions of microdischarges, characteristic for a DBD, influence individual gas molecules. We use a Monte Carlo approach to determine the number of microdischarges to which a single molecule would be exposed, by means of particle tracing simulations through a full-scale packed bed DBD reactor, as well as an empty DBD reactor. We find that the fraction of microdischarges to which the molecules are exposed can be approximated as the microdischarge volume over the entire reactor gas volume. The use of this concept provides good agreement between a plasma-catalytic kinetics model and experiments for plasma-catalytic NH3 synthesis. We also show that the concept of the fraction of microdischarges indicates the efficiency by which the plasma power is transferred to the gas molecules. This generalised concept is also applicable for other spatially and temporally non-uniform plasmas.
Accelerated decomposition of Bi2S3 nanorods in water under an electron beam: a liquid phase transmission electron microscopy study
Authors: Kim Su Yeon , Kim Ji Hyeon , Jeong Taehyeon , Kim Kyung Bin , Kim Hyung Joong , Nam Ki Min , Ahn Sang Jung , Kwon Ji Hwan , Kim Young Heon
Published: January 2021

Evaluating the stability of semiconductor photocatalysts is critical in the development of efficient catalysts. The morphological and microstructural behaviors of nanorod-shaped Bi2S3 semiconductors in aqueous solution were studied using a liquid cell transmission electron microscopy (TEM) technique. The rapid decomposition of Bi2S3 in water was observed under electron beam irradiation during TEM. Rounded bright spots due to a reduction in thickness were observed on the Bi2S3 nanorods at the initial stage of the decomposition, and rounded dark particles appeared outside of the nanorods in the solution, continuing the decomposition. This was confirmed by analyzing the atomic structure of the newly formed small particles, which consisted of an orthorhombic Bi2S3 phase. The stability-related decomposition of the Bi2S3 nanorods was demonstrated by considering the reduction and oxidation potentials of Bi2S3 in an aqueous solution. The effect of water radiolysis by the incident electron during TEM observations on the decomposition process was also determined by considering the time-dependent concentration behavior of the chemical species. Our study therefore reflects a novel route to evaluate the stabilities of semiconductor photocatalysts, which could ultimately solve a range of energy and environmental pollution problems.
3D MXene microspheres with honeycomb architecture for tumor photothermal/photodynamic/chemo combination therapy
Authors: Guo Yaping , Wang Hongshui , Feng Xin , Zhao Yunbo , Liang Chunyong , Yang Lei , Li Mingjun , Zhang Yongguang , Gao Wei
Published: January 2021

The MXene combining high surface area, prominent biocompatibility, and wide near infrared (NIR) absorption has been recognized as one of the most promising materials for tumor therapy. The application of MXene in tumor therapy is negatively affected by the current design methods lack the control of size distribution and the great tendency to agglomerate as well as poor photodynamic therapy. To solve the above problems, we report a facile strategy to process Ti3C2 nanosheets into three-dimensional (3D) structure with honeycomb structure and anti-aggregation properties for synergistic therapy of chemotherapy, photothermal and photodynamic therapy. The 3D MXene is synthesized by spray drying, in which the MXene surface is oxidized to TiO2. The microspheres present prominent NIR light trigger photothermal effect and excellent NIR light photostability, which respond in an on–off manner. Moreover, the microspheres exhibit outstanding drug-loading capability of doxorubicin (DOX) as high as 87.3%, and substantial singlet oxygen generation (1O2) was shown under 808 nm laser and UV light irradiation. Our studies indicate that 3D MXene-DOX could effectively achieve Hela cells killing in vitro, which provides a multifunctional drug delivery platform as a prospective candidate for future combined cancer therapy.
Visible light-induced antibacterial and osteogenic cell proliferation properties of hydrogenated TiO2 nanotubes/Ti foil composite
Authors: Zhao Yu , Lu Ran , Wang Xin , Huai Xiaochen , Wang Caiyun , Wang Yuji , Chen Su
Published: January 2021

We successfully fabricated the hydrogenated TiO2 nanotubes/Ti foil (H-TNTs/f-Ti) composite via one-step anodization and two-step annealing. H-TNTs/f-Ti composite had a higher visible light-induced photoelectric response and more hydroxyl functional groups compared with Ti foil and unmodified TiO2 nanotubes/Ti foil composite, which contributed to limiting the proliferation of Streptococcus mutans and Porphyromonas gingivalis, promoting the proliferation of MC3T3-E1 cell on the hydroxylated surface, and improving the biocompatibility with osteogenic cells. Our study provides a simple and effective method for significantly improving dental implant efficacy.
The experimental solution of the elevator problem
Authors: Lopes Coelho Ricardo
Published: January 2021

This paper combines the physics of the Atwood machine and the classic elevator problem. An Atwood machine equipped with accelerometers is used to determine the acceleration in the bodies’ frames. The product of this acceleration by the mass of the body gives us the weight of the body in that frame. The body that accelerates up weighs more than in the laboratory and the body that accelerates down weighs less. The elevator is then a particular case of this. The upward or downward accelerated motion of an elevator will have the same effect on the acceleration inside the elevator, as the acceleration of the bodies on an Atwood machine has on the accelerations in the bodies’ frames. The weight of a body inside the elevator is given by the product of mass and the inside acceleration, as the weight of the body in its own frame. As this acceleration is greater or smaller than the free fall acceleration in the laboratory, the body’s weight in an elevator will be greater or smaller than the weight in the laboratory.
Shear-lag modelling of surface-bonded magnetostrictive transducers for shear horizontal wave generation in a non-ferromagnetic plate
Authors: Wen Fuzhen , Shan Shengbo , Radecki Rafal , Staszewski Wieslaw J , Cheng Li
Published: January 2021

The fundamental shear horizontal (SH) wave in thin-walled structures shows appealing features for structural health monitoring (SHM) applications. Its efficient generation and reception however remain a critical and challenging issue. Magnetostrictive transducers (MsTs) show proven ability in exciting strong SH waves due to the high piezomagnetic coefficient of the ferromagnetic foil. In this study, to investigate the fundamental SH wave generation using MsTs and their design, a theoretical model is established based on the shear-lag model and the normal mode expansion method. The coupling of an MsT with a host plate is achieved by a bonding layer, whose mechanical property is modelled through the continuous shear stress across the thickness. The theoretical model is validated using finite element simulations in terms of generation mechanism and some typical features associated with the fundamental SH wave component. Meanwhile, wave field is visualized using a 3D Laser scanning vibrometer system. Experimental results within a wide frequency range show a good agreement with the theoretically predicted results. Influences of the coil configuration and bonding conditions are further investigated using the proposed model. The study offers guidelines to system design and optimization for fundamental SH wave generation in views of guided-wave-based SHM applications.
The influence of temperature on levitation properties of CC-tape stacks
Authors: Osipov M , Starikovskii A , Anishenko I , Pokrovskii S , Abin D , Rudnev I
Published: January 2021

This article presents the study of the temperature effect on the levitation characteristics of stacks of CC-tapes from various manufacturers SuperOx, Theva and Sunam. Tapes differ in the values of the critical current density, architecture, and parameters of the metal substrate. Stacks of tapes were assembled from 12 by 12 mm square pieces of CC-tape. The number of elements in the stacks varied from 5 to 70. The dependences of the levitation force Fz
(the vertical component of the force in the system permanent magnet—HTSC stack) on temperature were obtained both in zero field cooling (ZFC) and in field cooling (FC) modes. The measurements were carried out in the temperature range of 32–100 K. We have established that, down to the minimum operating temperatures, a decrease in temperature leads to a continuous increase in levitation force in ZFC mode. In FC mode, the Fz
value tends to saturate after the initial increase in force. Cooling below the boiling point of liquid nitrogen up to 65 K gives a levitation force gain of 5%–10%. At the same time, cooling to 35 K gives an increase in levitation force by 7%–23%. It was found that an increase in the number of elements in the stack from 5 to 70 leads to an increase in the levitation force with a tendency to saturation for all temperatures studied. Excellent agreement between the experimental and calculated dependences of the levitation force on temperature and the number of elements in the stacks is demonstrated. Calculations show that for Sunam tapes, 90% of the levitation force is achieved with a stack thickness of 100 tapes at the boiling point of liquid nitrogen, and with 70 tapes at lower temperatures. The distributions of the magnetic field during the approach/removal of magnets, as well as the distribution of the trapped magnetic flux at different temperatures and numbers of elements in the stacks are modelled.
Combined atomic clock with blackbody-radiation-shift-induced instability below 10−19 under natural environment conditions
Authors: Yudin V I , Taichenachev A V , Basalaev M Yu , Prudnikov O N , Fürst H A , Mehlstäubler T E , Bagayev S N
Published: January 2021

We develop a method of synthetic frequency generation to construct an atomic clock with blackbody radiation (BBR) shift uncertainties below 10−19 at environmental conditions with a very low level of temperature control. The proposed method can be implemented for atoms and ions, which have two different clock transitions with frequencies ν
1 and ν
2 allowing to form a synthetic reference frequency ν
syn = (ν
1 − ɛν
2)/(1 − ɛ), which is absent in the spectrum of the involved atoms or ions. Calibration coefficient ɛ can be chosen such that the temperature dependence of the BBR shift for the synthetic frequency ν
syn has a local extremum at an arbitrary operating temperature T
0. This leads to a weak sensitivity of BBR shift with respect to the temperature variations near operating temperature T
0. As a specific example, the Yb+ ion is studied in detail, where the utilized optical clock transitions are of electric quadrupole (S → D) and octupole (S → F) type. In this case, temperature variations of ±7 K lead to BBR shift uncertainties of less than 10−19, showing the possibility to construct ultra-precise combined atomic clocks (including portable ones) without the use of cryogenic techniques.
Asteroid Observations from the Transiting Exoplanet Survey Satellite: Detection Processing Pipeline and Results from Primary Mission Data
Authors: Woods Deborah F. , Ruprecht Jessica D. , Kotson Michael C. , Main Erin L. , Evans Elizabeth W. , Varey Jacob D. , Vaillancourt John E. , Viggh Herbert E. M. , Brown Joshua J. , Pál András
Published: January 2021

The Transiting Exoplanet Survey Satellite (TESS) is a NASA Explorer-class mission designed for finding exoplanets around nearby stars. TESS image data can also serve as a valuable resource for asteroid and comet detection, including near-Earth objects (NEOs). In order to exploit the TESS image data for moving object detection and potential object discovery, our team has developed an image processing pipeline as part of the Lincoln Near-Earth Asteroid Research (LINEAR) program, sponsored by the NASA NEO Observations Program. The LINEAR-TESS pipeline is currently in operation and reporting asteroid observations to the Minor Planet Center. In this paper we discuss the algorithms and methodology utilized to push the limits of the astrometric accuracy and photometric sensitivity of the TESS instrument for asteroid detection without a priori information on the ephemerides of the objects, and report on observation statistics from the first two years of TESS mission data.
An improved semi-empirical relationship for cluster radioactivity *
Authors: Wang Yanzhao , Xing Fengzhu , Xiao Yang , Gu Jianzhong
Published: January 2021

An improved semi-empirical relationship for cluster radioactivity half-lives is proposed by introducing an accurate charge radius formula and an analytic expression of the preformation probability. Moreover, the cluster radioactivity half-lives for the daughter nuclei around 208Pb or its neighbors and the 12C radioactivity half-life of 114Ba are calculated within the improved semi-empirical relationship. It is shown that the accuracy of the new relationship is improved significantly compared to its predecessor. In addition, the cluster radioactivity half-lives that are experimentally unavailable for the trans-lead and trans-tin nuclei are predicted by the new semi-empirical formula. These predictions might be useful for searching for the new cluster emitters of the two islands in future experiments.
Preparation of Si3N4-YAG mixtures for the spark plasma sintering method
Authors: Andreev P V , Drozhilkin P D , Alekseeva L S , Rostokina E Ye , Karazanov K O , Boldin M S , Balabanov S S
Published: January 2021

In order to obtain ceramics based on Si3N4 with improved physical and mechanical properties, methods of creating composites for their subsequent consolidation by the spark plasma sintering method were investigated. Four different methods of producing mixtures based on the Si3N4 and Al5Y3O12 (YAG) precursor were considered in order to obtain a homogeneous distribution of the YAG sintering additive on the surface of the Si3N4 particles. It is shown that the YAG and Y-Si-Al-O-N phases are formed by co-precipitation, deposition in a gelatin matrix and Pecini methods. The spray drying method does not lead to the formation of the YAG phase. This may indicate a high homogeneity of the YAG coating on the surface of the Si3N4 particles, preventing the growth of crystalline particles.
Degradation of the creep resistance of a Re-containing 10%Cr steel upon creep testing at low applied stress
Authors: Fedoseeva A E , Nikitin I S , Fedoseev A E , Kaibyshev R O
Published: January 2021

New Re-containing steel is a promising material for steam blades of fossil power plants worked at ultra-supercritical parameters of the steam. This steel was subjected to creep testing at 650°C under the applied stresses ranging from 200 to 100 MPa. The steel exhibits excellent creep resistance at high applied stresses; the time to rupture comprises 10,987 hours after the creep test at 650°C/140 MPa. However, a dramatic drop in the creep strength is observed at low applied stresses. A possible reason for this decrease in the creep resistance may be a significant coarsening of the Laves phase particles.
Effect of thermal treatment on the structure and hardness of the laser powder bed-fused Ti-Zr-Nb shape memory alloy
Authors: Kalinicheva V , Sheremetyev V , Letenneur M , Konopatsky A , Prokoshkin S , Brailovski V
Published: January 2021

A new biomedical Ti-18Zr-14Nb (at.%) alloy was processed using the laser powder bed fusion additive manufacturing technology and subjected to post-fusion annealing in the 400 to 900 °C temperature range. The meltpool and grain structure features, the phase composition and hardness of samples fabricated using different laser energy densities and build rates, while having identical printed material densities, were analyzed. It was shown that the microstructure of the alloy differs depending on the printing parameters used. The higher the energy density, the coarser in size and the more elongated towards the build plate grains are formed during the process. Subsequent annealing results in the formation of different structures depending on the printing conditions, and the smaller the as-built grain size, the lower the onset temperature of recrystallization, which starts up to 100 °C lower for the finer grain structure than for the coarser grain structure of this study.
Ultralow-cobalt hard alloys obtained by spark plasma sintering
Authors: Lantsev E A , Chuvil’deev V N , Nokhrin A V , Boldin M S , Malekhonova N V , Blagoveshchenskii Y V , Isaeva N V , Tsvetkov Y V , Andreev P V , Smetanina K E
Published: January 2021

The features of spark plasma sintering (SPS) of plasma-chemical nanopowders WC-(0.3, 0.6, 1) wt.% Co were studied. The SPS process of ultralow-cobalt hard alloys can be sequentially represented as a change of the following mechanisms: rearrangement of particles at lower temperatures (Stage I) → sintering of WC-Co particles due to Coble diffusion creep of cobalt, the intensity of which is determined by the grain boundary diffusion rate (Stage II ) → sintering due to diffusion creep, the rate of which is limited by the bulk diffusion in cobalt (Stage III-1) → sintering of tungsten carbide particles along the intergranular boundaries of WC / WC under conditions of intensive grain growth (Stage III-2). Samples with a high density (96.4-98.4%) and high mechanical properties were obtained (for the WC-0.3% Co hard alloy: Hv ∼ 20.5 GPa, KIC = 7.1 MPa · m1/2).
Method of molecular dynamics investigation of diffusion in solid solutions with consideration of ordering effects on the example of V50W50 and V90W10 alloys
Authors: Lipnitskii A G , Maksimenko V N , Nelasov I V
Published: January 2021

This paper presents the development of methods for the theoretical study of diffusion processes in solid solutions based on molecular dynamics (MD), taking into account the effects of ordering. The influence of concentration and temperature on the features of diffusion characteristics in substitution alloys is studied using the example of solid solutions V50W50 and V90W10. Modeling has shown that the V-W ordering is associated with the separation of plates enriched with tungsten in the planes (100). Vanadium atoms are more mobile and the difference in diffusion coefficients decreases with the equalization of component concentrations and temperature increases.
Methodological approaches to the study of reverse martensitic transformation in metastable austenitic steels
Authors: Panov D O , Smirnov A I , Simonov Y N , Stepanov N D , Salishchev G A
Published: January 2021

Methodological aspects of the high-resolution dilatometry analysis of the reverse α→γ-transformation in cold-worked metastable austenitic steel Fe-0.07C-18.7Cr-9.2Ni-0.6Ti-1.1Mn-0.4Si (wt.%) were considered. It was shown that the reverse α→γ-transformation occurs in the temperature range from AS=520 °C to AF=920 °C. Two consecutive stages corresponding to shear and diffusion transformations were revealed. An abnormal increase in the sample length of the program steel during the reverse α→γ-transformation was found. The recrystallization process also developed during austenitization and was accompanied by a decrease in length of the specimen.
Creep behavior and microstructure of a Ta-added 9%Cr steel with high B and low N contents
Authors: Tkachev E , Belyakov A
Published: January 2021

The creep behavior and microstructure of an advanced a Ta-added 9%Cr steel were investigated. The steel is characterized by increased strength in the long-term creep regime, which can be associated with fine dispersion of (Nb,Ta)(C,N) particles. Strengthening of the studied steel due to the fine MX particles was estimated using the Orowan particle strengthening model.