bluuebunny/crossref_metadata_2025 huggingface dataset:
Research on the Defrosting System of Refrigerated Containers Combining Air and Electro-Thermal Energy and the Controlling Strategy
Authors: Hua Kaitai
Published: April 2021

Considering the problems such as long duration of defrosting, low working reliability and high energy consumption of refrigerated containers, this paper put forward a new defrosting method combining air and electro-thermal energy, and designed a new defrosting structure system based on the structural features of refrigeration modules of refrigerated containers. The two-variable method of wind pressure change and temperature difference change on both sides of the evaporator was used to detect frosting, and the specific controlling strategy supporting the new defrosting system was provided to realize the effect of intelligent defrosting. It can provide references for fast defrosting, intelligent defrosting and low energy consumption defrosting of refrigerated containers.
The structural design of Kunshan Xintiandi super high-rise office building
Authors: Zhang Xiaomeng , Liu Wenting , Zhou Yilun , yang Xiao , Liu Ziao
Published: April 2021

The Kunshan urban investment project includes 1 office tower, 4 high-rise residential buildings and 1 high-rise commercial building. Each monomer shares a large basement chassis, a total of three basement floors. This design is the second phase (5# super high-rise and corresponding basement).The height of the structure is more than 140 meters, which is a concrete-filled steel tubular frame + core tube system. The selection and structure of the structural system are analyzed, and the mechanical performance of the structure is verified through calculation and analysis.
Application of ANP-PCE in post evaluation of water conservancy project
Authors: Chen Xinyi
Published: April 2021

Combined with the characteristics of post evaluation of water conservancy projects, this paper presents an integrated comprehensive evaluation method based on the combination of fuzzy comprehensive evaluation and network analysis, namely ANP-PCE method. Then the applicability and scientificity of the ANP-PCE method are verified by taking a water conservancy project in Shaanxi Province as an example. The research shows that: in the post evaluation of water conservancy project, the ANP-PCE method has strong accuracy and reliability, the evaluation method shows strong applicability, and has a certain promotion value.
Application Status and Trend of Sensors in Domestic Engineering Field
Authors: Xu Binbin
Published: April 2021

From the perspective of engineering field, this paper introduces the application of sensors in engineering field, and then forecasts the application trend of sensors in engineering field by introducing the status quo of sensors in engineering field, especially in the field of comprehensive treatment of water environment.
Research on Status and Improvement of Indoor Thermal Environment for Existing New Rural Building in Chengdu
Authors: Li Ling
Published: April 2021

Through the practical measurement and theoretical calculation of the indoor thermal parameters about the existing new rural building in Chengdu, this paper concludes that the indoor thermal environment of Chengdu is very poor. In addition, we propose an energy saving improvement scheme according to the “Design Standard for Energy Efficiency of Rural Residential Buildings” GB/T50824-2013 and the local characters of Chengdu. We also simulate the indoor thermal environment of existing new rural building and improved building using Design-Builder software. As compared with the existing new rural building, we know that the improved building has greatly improved in the indoor thermal environment. The indoor average temperature decreases 2°C-6°C in summer and rises 2°C -7.7°C in winter. As to the humidity between 30% and 60%, the rise rate of each room reaches above 12.9% in summer and reaches 28.8% in winter. The rise rate of PMV index of -1 to +1 reaches above 68.4% in summer and 54.4% in winter from below 20%. The improved building meets the living requirements for local resident in most time.
Design and bearing capacity analysis of cold-formed thin-walled steel-timber composite members
Authors: Pan Futing , Wang Ying , Huang Chunxiao
Published: April 2021

Cold-formed thin-walled steel has light weight, large width thickness ratio, good economy and seismic performance. It is easy to realize standardization of design, and is very suitable for the development of prefabricated buildings. Due to the large width thickness ratio of cold-formed thin-walled steel , the steel plate is prone to local buckling when it is compressed, which will reduce the ductility and bearing capacity of the structure, which also leads to the limitation of the use of cold-formed thin-walled steel structure system in medium and high-rise buildings. In this paper, a kind of cold-formed thin-walled steel-timber composite members is designed. The section steel and the board are closely linked by bolts to work together. The thickness of the board and the spacing of the bolts are designed respectively, so as to provide reference for engineering design.
Discussion on controlling measures and the influence of engineering change
Authors: Zhu Zhigang
Published: April 2021

This paper discusses the engineer change of the main causes and influence on engineering cost, calculated the reasonable method to avoid and control engineering change and approach, in order to achieve the purpose of scientific management to effectively control investment through analyzing the engineering change in detail, and combined closely with the project cost.
A dynamic post-evaluation analysis strategy based on Space syntax for optimizing middle school campus layout
Authors: Guo Kexin , Peng Guoqing , Pang Jining , Shen Shuaibing , Lin Xuewen , Wan Qian
Published: April 2021

Space syntax has injected new vitality into quantitative and parameterized planning and design of middle school campus. Although, there are extensive interpretative problems in space syntax that need to be clarified during engineering planning and design of campus. This paper focuses on: (1) the parameters and models of space syntax are clarified from the perspectives of planning and design; (2) the specific application of space syntax in campus planning and design is discussed from the four stages of preliminary research, scheme analysis, scheme design and scheme optimization; (3) a relatively reliable quantitative, visual and procedural post-evaluation system of campus planning and design is provided with GIS spatial analysis technology and dynamic simulation means.
Quality inspection method of layered compacted subgrade and engineering example analysis
Authors: Xu Binbin
Published: April 2021

The effective detection of layered roller compacted subgrade quality is the key of road engineering quality control. The traditional sand filling compaction method belongs to random sampling point detection method, and it is not easy to detect the subgrade compaction condition below the sand filling pit. Based on the summary of the current domestic and foreign subgrade detection technology, this paper innovatively combines the geological radar method with sand filling method, and through the fixed point detection method. The results show that the traditional sand filling method can directly and quantitatively reflect the compactness of sampling points, while the geological radar can realize the continuous detection, and can judge the compaction layer from the loose state to the interlaminar line after compaction through the geological radar image At the same time, the GPR can identify the under compacted area in the subgrade compaction layer and reflect the overall compaction effect of the subgrade. The detection method of combining the GPR method and sand filling method has obvious technical advantages in the subgrade quality detection.
Research on Seismic Performance of New Prefabricated Strengthen-weaken Beam-column Connection Joints
Authors: Xin Li , Xiaojie Zhang , Xudong Tao
Published: April 2021

In order to realize the design concept of “strengthened column and weakened beam, strengthened connection joints and weakened components” and ensure the improvement of joints’ bearing capacity and the transfer of plastic hinges along beams far away from column ends, this paper proposes a new type of prefabricated beams with strengthen-weaken beam-column connection, and changes multiple parameters. Six connection joint models are designed for finite element analysis. The results show that: JD-1 is located far away from the column end according to the plastic development trend, which is in line with the purpose of transfer of the plastic hinges at the beam end. In addition, the whole column is barely damaged during the whole loading process of this connection joint, and quick recovery after the earthquake could be realized merely by replacing other related components of the joint in the later period. Changes of different parameters also have certain impact on the bearing capacity, seismic resistance and energy dissipation capacity of the joint.
Application of BP Neural Network Model in the Evaluation of Urban Land Intensive Utilization
Authors: Xiongfei Yang , Xitun Yuan , YongXiao Wen , Hang Zhang , Qi Han
Published: April 2021

Using BP neural network model to analyze the urban land development status of Zhengzhou City from 2013 to 2017, the evaluation grades are divided into over-utilization, intensive use, moderate utilization and extensive utilization, and from the land input intensity, land use intensity and a total of nine indicators were selected for evaluation in three aspects of land output benefits. The results show that the urban land intensive degree of Zhengzhou City during the five years from 2013 to 2017 is 0.3039, 0.5118, 0.6189, 0.6914, 0.8509, and the intensive degree is gradually increased every year. The degree of intensive use is gradually increased every year, the evaluation level has risen from extensive use to intensive use, and the intensity of land intensive use has continued to increase.
Research on apple orchard classification and yield estimation model based on GF-1 and Sentinel-2
Authors: Liu Yu , Wang Xiaoping , Qian Jiaxin
Published: April 2021

China is a big apple planting country and attaches great importance to the development of apple industry in agricultural economy. There are many mountainous areas in Shaanxi Province, which has obvious geographical advantages and is one of the important areas for apple production in my country. A quick and effective forecast of the apple output in Shaanxi Province can not only strengthen the management of apple planting and production, improve the varieties of apple production, and improve the quality of apple production, but also provide technical support for regional agricultural departments to expand the apple market and improve the base construction. It is of great significance to promote the rapid development of my country's apple planting industry. In this study, Luochuan County, Yana’s City, Shaanxi Province was used as the research area, using GF-1 and Sentinel-2 multispectral remote sensing images and their vegetation indices from 2013 to 2019, and using RF to extract orchards in the research area. Secondly, combining the classification results with rainfall, temperature, sunshine hours, air pressure, humidity, wind speed, drought indicators and remote sensing vegetation index, using RFR and SVR methods, establish a comprehensive production estimation model suitable for Luochuan County apples, and compare different types Model accuracy. The main conclusions are drawn through the research: Using RF classification method can effectively extract the luochuan orchard distribution and high precision, based on RFR and SVR method combined with meteorological factor, the drought index and remote sensing vegetation index to establish basic quite, crop yield estimation model precision machine learning regression algorithm for subsequent apple luochuan orchard management, and provide strong decision basis for the development of apple industry.
Research on Teaching Scheme of Introduction to Engineering Management Based on the EPMI
Authors: Cai Hualong , Ouyang Ming , Zhu Chengyu , Peng Chen
Published: April 2021

Introduction to Engineering Management is recognized as the first enlightening course for freshmen majoring in engineering management. Its teaching effect significantly impacts the cultivation of engineering management professionals. The engineering management professional certification management information platform refers to EPMI. By complying with the EPMI, this study investigates the teaching system of the ideological and political education of the course, teaching mode and teaching feedback mechanism. Compared with existing conventional teaching scheme, the novel teaching scheme enriches the content and form of the course, promotes the curriculum teaching system more systematic and scientific, helps students further clarify the focus of professional learning, which enables them to achieve the curriculum teaching goals more effectively.
L’apocalypse de Gaïa : la cosmopolitique pour l’Anthropocène de Bruno Latour
Authors: Corrêa Diogo Silva , Magnelli André Ricardo do P.
Published: April 2021

Nous vivons dans une société qui, tel unTitanicà la rencontre de son iceberg, persiste à accélérer vers une catastrophe incontrôlable. Les différents signes de la « grande accélération » de l’ère de l’Anthropocène s’accumulent sans cesse. Aurions-nous enfin acquis, avec la pandémie, une (nouvelle) sensibilité aux avertissements constants qui, souvent par lanceurs d’alerte, résonnent avec l’émergence du « nouveau régime climatique » ? Face à la folie de notre temps, c’est d’abord de la perplexité qu’affiche l’anthropologue et philosophe Bruno Latour. On propose de réfléchir ici aux défis actuels en dialogue avec la pensée de Latour sur la mutation écologique, notamment avec ses arguments présents dans deux de ses ouvrages,Face à GaïaetOù atterrir ?. Nous présentons son diagnostic du temps et ses propositions scientifiques, esthétiques et politiques, en montrant comment il entrelace les fils les plus divers de savoirs − science, politique, religion, esthétique, guerre – pour recomposer le monde et rendre la paix possible.
Advances and innovations in total hip arthroplasty
Authors: Fontalis Andreas , Epinette Jean-Alain , Thaler Martin , Zagra Luigi , Khanduja Vikas , Haddad Fares S.
Published: April 2021

Total hip arthroplasty (THA) has been quoted as one of the most successful and cost-effective procedures in Orthopaedics. The last decade has seen an exponential rise in the number of THAs performed globally and a sharp increase in the percentage of young patients hoping to improve their quality of life and return to physically demanding activities. Hence, it is imperative to review the various applications of technology in total hip arthroplasty for improving outcomes. The development of state-of-the-art robotic technology has enabled more reproducible and accurate acetabular positioning, while long-term data are needed to assess its cost-effectiveness. This opinion piece aims to outline and present the advances and innovations in total hip arthroplasty, from virtual reality and three-dimensional printing to patient-specific instrumentation and dual mobility bearings. This illustrates and reflects the debate that will be at the centre of hip surgery for the next decade.
Gastrointestinal defect closure using a novel through-the-scope helix tack and suture device compared to endoscopic clips in a survival porcine model (with video)
Authors: Hernandez Ariosto , Marya Neil B. , Sawas Tarek , Rajan Elizabeth , Gades Naomi M. , Wong Kee Song Louis M. , Abu Dayyeh Barham K. , Buttar Navtej , Storm Andrew C.
Published: April 2021

Background and aims Endoscopic resections are associated with bleeding and perforation and may be managed with through-the-scope (TTS) clips, over-the-scope clips and endoscopic suturing. The aim of this preclinical study was to compare technical success of closure using a novel TTS tissue helix tack and suture device (X-Tack) to TTS clips in a porcine model.

Materials and methods Four subjects underwent 40 mucosal resections, diameter range 25–50 mm, in the stomach (n = 24) and colon (n = 16). Closures were randomized to X-Tack (n = 24) or clip (n = 16). Animals underwent weekly endoscopic follow-up for 4 weeks.

Results Technical closure with X-Tack was successful in 24 of 24 (100 %) cases and with clips in 13 of 16 cases (81.3 %) (P = 0.0001). One colonic perforation occurred and was successfully managed using X-Tack. The rate of healing was not statistically different between the groups, and all sites healed at 4 weeks including the perforation and were confirmed by histology.

Conclusions Compared to TTS clip, X-Tack is superior for effecting large mucosal defect closure, including durable sealing of full-thickness perforation. There was no difference in rate of healing between devices.
Highly Efficient Visible-Light-Driven [2+2] Cycloaddition of Maleimides to Alkenes and Alkynes for the Synthesis of 3-Aza­bicyclo[3.2.0]heptane-Fused Scaffolds
Authors: Liu Qiang , He Jian
Published: April 2021

A highly efficient [2+2] cycloaddition between maleimides and unsaturated moieties, utilizing a visible-light triplet sensitization mode, has been developed for the direct synthesis of multifunctional 3-azabicyclo[3.2.0]heptane derivatives. This reaction relies on selective activation of the maleimide functionality upon energy transfer from a new photosensitizer that outperforms diverse well-established photosensitizers. The strategy developed herein overcomes previous obstacles such as limited substrate scope and undesired reaction pathways under harsh UV irradiation.
Health Care Utilization and Associated Economic Burden of Postoperative Surgical Site Infection after Spinal Surgery with Follow-Up of 24 Months
Authors: Dietz Nicholas , Sharma Mayur , Adams Shawn , Ugiliweneza Beatrice , Wang Dengzhi , Bjurström Martin F , Karikari Isaac , Drazin Doniel , Boakye Max
Published: April 2021

Background Surgical site infection (SSI) may lead to vertebral osteomyelitis, diskitis, paraspinal musculoskeletal infection, and abscess, and remains a significant concern in postoperative management of spinal surgery. SSI is associated with greater postoperative morbidity and increased health care payments.

Methods We conducted a retrospective analysis using MarketScan to identify health care utilization payments and risk factors associated with SSI that occurs postoperatively. Known patient- or procedure-related risk factors were searched across those receiving spine surgery who developed postoperative infection.

Results A total of 33,061 patients who developed infection after spinal surgery were identified in Marketscan. Overall payments at 6 months, including index hospitalization for those with infection, were $53,573 and $46,985 for the cohort with no infection. At 24 months, the infection group had overall payments of $83,280 and $66,221 for no infection. Risk factors with largest effect size most likely to contribute to infection versus no infection were depression (4.6%), diabetes (3.7), anemia (3.3%), two or more levels (2.8%), tobacco use (2.2%), trauma (2.1%), neoplasm (1.8%), congestive heart failure (1.3%), instrumentation (1.1%), renal failure (0.9%), intravenous drug use (0.8%), and malnutrition (0.5%).

Conclusions SSIs were associated with significant health care utilization payments at 24 months of follow-up. The following clinical and procedural risk factors appear to be predictive of postoperative SSI: depression, diabetes, anemia, two or more levels, tobacco use, trauma, neoplasm, congestive heart failure, instrumentation, renal failure, intravenous drug use, and malnutrition. Interpretation of modifiable and nonmodifiable risk factors for infection informs surgeons of expected postoperative course and preoperative risk for this most common and deleterious postoperative complication to spinal surgery.
Efficacy of Internal Neurolysis for Trigeminal Neuralgia without Vascular Compression
Authors: Li Ming-Wu , Jiang Xiao-feng , Niu Chaoshi
Published: April 2021

Background and Objective Trigeminal neuralgia is a common neurologic disease that seriously impacts a patient's quality of life. We retrospectively investigated the efficacy and safety of internal neurolysis (nerve combing) for trigeminal neuralgia without vascular compression.

Patients and Methods This study was a retrospective review of all patients with trigeminal neuralgia who were admitted between January 2014 and February 2019. A subgroup of 36 patients had no vascular compression at surgery and underwent internal neurolysis. Chart review and postoperative follow-up were performed to assess the overall outcomes of internal neurolysis.

Results Thirty-six patients were identified, with a mean age of 44.89 ± 7.90 (rang: 31–65) years and a disease duration of 5.19 ± 2.61 years. The immediate postoperative pain relief (Barrow Neurological Institute [BNI] pain score of I or II) rate was 100%. The medium- to long-term pain relief rate was 91.7%. Three patients experienced recurrence. Facial numbness was the primary postoperative complication. Four patients with a score of III on the BNI numbness scale immediately after surgery had marked improvement at 6 months. No serious complications occurred.

Conclusion Internal neurolysis is a safe and effective treatment for trigeminal neuralgia without vascular compression or clear responsible vessels.
Emergent Hybrid Treatment of a Ruptured Scalp Arteriovenous Fistula with Eyelid involvement: Technical Note
Authors: Abaunza-Camacho Juan Felipe , Vergara-Garcia David , Perez Francisco , Benavides Camilo , Caballero Alberto , Torres Jorge , Riveros William Mauricio
Published: April 2021

Background Scalp arteriovenous fistulas (AVFs) are a rare vascular disease usually presenting as a progressively increasing pulsating mass in the scalp. These lesions can be associated with mild to severe complications, including congestive heart failure. If ruptures, this pathology constitutes a life-threatening medical emergency because of its potential to cause severe bleeding and acute anemia.

Methods We describe the case of a young woman with a ruptured Yokouchi type C scalp AVF with eyelid involvement.

Results The patient presented with hypovolemic shock and acute anemia due to severe bleeding from the lesion. Emergent treatment through a combined endovascular and open surgical approach was required to stop bleeding and stabilize the patient.

Conclusions Emergent and effective treatment is required to stop bleeding when a scalp AVF ruptures. A combination of endovascular embolization and microsurgical excision of the shunt is a treatment option.
HIV and Surgery for Degenerative Spine Disease: A Systematic Review
Authors: Farias Frederico Arriaga Criscuoli , Dagostini Carolina Matté , Falavigna Asdrubal
Published: April 2021

Background and Study Aims The objective of this review is to evaluate the incidence of operative treatment, outcomes, and complications of surgery for degenerative spine disease (DSD) on human immunodeficiency virus (HIV) positive patients. Combined antiretroviral treatment led HIV patients to live long enough to develop many chronic conditions common in the uninfected population. Surgery for DSD is one of the most commonly performed neurosurgical procedures. However, the incidence of spine surgery for DSD in HIV-positive patients seems to be lower than that in uninfected individuals, although this has not been clearly determined.

Methods A systematic search of the Medline, Web of Science, Embase, and SciElo databases was conducted. Only primary studies addressing DSD surgery on HIV-positive patients were included. Evaluated variables were rates of surgical treatment, surgical outcomes and complications, year of publication, country where study was conducted, type of study, and level of evidence.

Results Six articles were included in the review from 1,108 records. Significantly lower rates of DSD surgery were identified in HIV-infected patients (0.86 per 1,000 patient-years) when compared with uninfected patients (1.41 per 1,000 patient-years). There was a significant increase in spinal surgery in HIV-positive patients over time, with a 0.094 incidence per 100,000 in the year 2000 and 0.303 in 2009. HIV-positive patients had very similar outcomes when compared with controls, with 66.6% presenting pain relief at a 3-month follow-up. Higher incidences of hospital mortality (1.6 vs. 0.3%; p < 0.001) and complications (12.2 vs. 9.5%, p < 0.001) were observed in HIV carriers.

Conclusions HIV-positive individuals appear to undergo less surgery for DSD than HIV-negative individuals. Improvement rates appear to be similar in both groups, even though some complications appear to be more prevalent in HIV carriers. Larger studies are needed for decisive evidence on the subject.
Vasodilator-Stimulated Phosphoprotein to Monitor Clopidogrel Posology in a 7-Year-Old Child Stented for a Post-Traumatic Intracranial Internal Carotid Artery Aneurysm
Authors: Hess Valentin , Zhu François , Miguel Justine , Girard Florent , Toussaint Marie , Klein Olivier , Anxionnat René , Wiedemann Arnaud
Published: April 2021

Many pediatric medical protocols or drug posology like biantiplatelet therapy are extrapolated from adult care. This association could be indicated in specific pediatric situations such as ischemic stroke, some cardiac conditions, or to control post stent thrombosis/stenosis. If acetylsalicylic acid is commonly used, few data are available about optimal management of clopidogrel in children. We describe the case of a 7-year-old girl admitted to pediatric intensive care unit who undergoes a transitory hemiparesis after a bicycle accident. Brain magnetic resonance imaging reveals a subarachnoid hemorrhage and a wide right Sylvian arachnoid cyst. Hemorrhage predominated at the level of the optochiasmatic cistern, close to the right internal carotid artery. At the same level, angiography revealed a small aneurysm of the internal carotid artery supposed to be a postfalse traumatic aneurysm. The deployment treated this aneurysm of a flow diverter. The treatment was performed under continuous systemic heparin therapy associated with intravenous acetylsalicylic acid, and Clopidogrel was administered immediately after the procedure. An oral bi antiplatelet treatment was initiated the day 2 with acetylsalicylic acid and clopidogrel (1 mg/kg/day). To monitor clopidogrel posology, a vasodilator-stimulated phosphoprotein [VASP]) was performed. The final VASP assay result was 20% for a clopidogrel posology at 0.5 mg/kg/day. Blood pressure and neurological examination were normal during all the hospitalization. VASP assay can be used in children to define the optimal posology of clopidogrel. Further studies are required to determine an optimal initial posology.
The physics of snapping a twig
Authors: Yiu Yuen
Published: April 2021

By studying the mechanical properties of jujube branches, researchers learned how much to trust computer models when studying microstructures in the natural world.
Twisted cohomotopy implies twisted string structure on M5-branes
Authors: Fiorenza Domenico , Sati Hisham , Schreiber Urs
Published: April 2021

We show that charge-quantization of the M-theory C-field in J-twisted Cohomotopy implies the emergence of a higher Sp(1)-gauge field on single heterotic M5-branes, which exhibits a worldvolume Stringc2-structure.
Pyroelectric and photovoltaic properties of Nb-doped PZT thin films
Authors: Berenov A. , Petrov P. , Moffat B. , Phair J. , Allers L. , Whatmore R. W.
Published: April 2021

Nb-doped lead zirconate titanate (PZT) films with up to 12 at. % of Nb were co-sputtered from oxide PZT and metallic Nb targets at a substrate temperature of 600 °C. Up to 4 at. % of Nb was doped into the perovskite structure with the formation of B-site cation vacancies for charge compensation. The preferential (111) PZT orientation decreased with Nb-doping within the solid solution region. The ferroelectric response of the films was affected by the large values of the internal field present in the samples (e.g., −84.3 kV cm−1 in 12 at. % Nd doped films). As-deposited unpoled films showed large values of the pyroelectric coefficient due to self-poling. The pyroelectric coefficient increased with Nb-doping and showed a complex dependence on the applied bias. The photovoltaic effect was observed in the films. The value of the photocurrent increased with the A/B ratio. The combined photovoltaic–pyroelectric effect increased the values of the measured current by up to 47% upon light illumination.
A novel device for in situ study of gas adsorption under rotation
Authors: Kosheleva R. I. , Karapantsios T. D. , Kostoglou M. , Mitropoulos A. Ch.
Published: April 2021

The effect of rotation on adsorption kinetics of CO2 on activated carbon (AC) is studied using a novel rotation device. The device consists of a rotating cylindrical cell with inner dimensions of 4.5 cm radius and 1 mm height, while it operates at 5000 and 8000 rpm. Various cases of the CO2/AC system are examined under a rotation field: in particular, (a) solid at vacuum, (b) gas without solid, (c) gas/solid at a non-equilibrium state of the adsorption process, and (d) gas/solid near an equilibrium state of the adsorption process. Micro-fragmentation of solid particles is observed at 8000 rpm but not at 5000 rpm; the latter is then chosen as the preferable speed for the rest of the experiments. During rotation of the gas, a well is noticed at the pressure curve, the size of which is in accordance with theoretical predictions of the behavior of a spinning gas. Rotation at an early stage of the adsorption process can suppress the filling time of a rotating storage reservoir to half of its value. Rotation near the equilibrium point reveals an enhanced adsorption capacity of the solid. The physics behind these phenomena are discussed with the aid of N2-adsorption porosimetry and scanning electron microscopy measurements.
Fermi level tuning and the robustness of topological surface states against impurity doping in Sn doped Sb2Te2Se
Authors: Mallick Debarghya , Mandal Shoubhik , Ganesan R. , Anil Kumar P. S.
Published: April 2021

In this work, we have studied the transport properties of two different single crystals, Sb2Te2Se and Sn-doped Sb2Te2Se. By analyzing the Shubnikov–de Haas oscillations for the devices made from both the crystals, we have extracted the Berry phase. The non-trivial value of the Berry phase for both the samples unambiguously indicates the robustness of the topological surface states against the impurity doping. The parent compound is n-type due to excess Te vacancies, and we could show from the sign of the intercept in the Landau level fan diagram and from the Hall effect measurements that doping with Sn makes it p-type. This demonstrates the tuning of the Fermi level in a topological insulator upon Sn doping.
Acoustic radiation force on a free elastic sphere in a viscous fluid: Theory and experiments
Authors: Qiao Yupei , Gong Menyang , Wang Haibin , Lan Jun , Liu Teng , Liu Jiehui , Mao Yiwei , He Aijun , Liu Xiaozhou
Published: April 2021

An expression was derived from the theory for the acoustic radiation force (ARF) acting on a free spherical particle in a viscous fluid subject to an incident plane wave. In deriving this ARF, the viscosity of the fluid, the elasticity of the particle, and the particle's state when suspended freely in the liquid were considered together. Corresponding experiments were designed and conducted. To compare the ARFs measured in experiments with those predicted by theory, a sphere made of polystyrene was taken as the target particle. Based on experimental and theoretical calculations, the effects of the incident sound pressure amplitude, the frequency of the acoustic wave, and fluid viscosity were analyzed. The analysis showed that the ARF increases with increasing pressure amplitude or dynamic viscosity. There is a series of maxima or minima in the ARF that depends on dimensionless frequency kR. Moreover, the theoretical and experimental values are in good agreement. This work provides an advanced ARF theory that is able to predict real-world behavior more accurately.
Comment on “Application of Fourier transform to MHD flow over an accelerated plate with partial-slippage,” [AIP Advances 4, 067104 (2014)]
Authors: Chishtie Farrukh A.
Published: April 2021

In this comment, I communicate corrected solutions for the article by Ahmad et al. [AIP Adv. 4, 067104 (2014)].
On the analogy between rigid plate motion and mean momentum transfer in surface gravity waves
Authors: Weber Jan Erik H. , Christensen Kai H.
Published: April 2021

The transfer of mean momentum from surface gravity waves to Eulerian mean fluxes is investigated by modeling the total wave momentum (the Stokes flux) as a thin surface layer moving with the phase speed c of the waves and with a thickness Z derived from the divergence effect. The bulk of the fluid receiving momentum from the waves is modeled by a rigid lower layer acted upon by the virtual wave stress, where the latter is related to the form stress from the wind and the time rate of change in Z through −cdZ/dt. In addition, the effects of surface wind and bottom stress are included in the model. Through the combination with measurements, this robust model may yield information about the Eulerian fluxes when the ocean surface is covered by a combination of ice and oil, and the constitutive equations for the surface cover are not easily obtained.
Micro-ocean-bottom electromagnetic receiver for controlled-source electromagnetic and magnetotelluric data acquisition
Authors: Dong Zhe , Zhang Jing , Yang Guoyi , Cai Zhenyu , Lu Yongjian , Chen Kai
Published: April 2021

A new micro-ocean-bottom electromagnetic (EM) receiver is presented for marine magnetotelluric (MT) and controlled-source EM (CSEM) data acquisition, avoiding the bulkiness, high cost, high power consumption, and narrow bandwidth of the existing ocean-bottom EM receivers. The efficient, compact, and easy-to-use data logger employs a single 17-in. spherical glass as a float and uses an acoustic telemetry modem unit to control the burn-wire release of the seafloor instrument via a smartphone. The receiver design involves two induction coils for the magnetometer and four 8-m-span electric-field sensors for MT and CSEM data acquisition. The new ocean-bottom EM receiver was tested in sea. Compared with other miniaturized seabed EM receivers, the proposed receiver achieves better comprehensive performance for MT and CSEM data acquisition and meets the requirements of deep-mantle-structure research and seabed resource exploration.
Mitigating the formation of amorphous shear band in boron carbide
Authors: Shen Yidi , Fuller Jon , An Qi
Published: April 2021

Boron carbide is super-strong and has many important engineering applications such as body armor and cutting tools. However, the extended applications of boron carbide have been limited by its low fracture toughness arising from anomalous brittle failure when subjected to hypervelocity impact or under high pressure. This abnormal brittle failure is directly related to the formation of a tiny amorphous shear band of 2–3 nm in width and several hundred nm in length. In this Perspective, we discuss mitigating the amorphous shear bands in boron carbide from various strategies including microalloying, grain boundary engineering, stoichiometry control, and the addition of a second phase. Combined with recent theoretical and experimental studies, we discuss strategies that can be applied in synthesizing and producing boron carbide-based materials with improved ductility by suppressing the formation of the amorphous shear band.
Single-crystal elastic and thermodynamic properties of γ-LiAlO2
Authors: Haussühl Eiken , Bayarjargal Lkhamsuren , Ruiz-Fuertes Javier
Published: April 2021

The elastic properties of γ-LiAlO2 were reinvestigated with the aid of resonant ultrasound spectroscopy (RUS) at ambient conditions. A strong discrepancy of the elastic coefficients derived by RUS can be found from the experimental results from the literature, where c12 and c13 deviate from our results by up to 60% (46 GPa). In contrast to the experimental cij from the literature, we can recognize a good agreement between the elastic coefficients derived from RUS and the values using density functional theory. The dielectric permittivity was measured on large plane-parallel plates, and the piezoelectric stress coefficient e123=0.14Cm−2 was derived from RUS measurements at ambient conditions. The heat capacity between 4 and 398 K has been obtained by microcalorimetry using a relaxation calorimeter. The Debye temperature was derived from heat capacity measurements (ΘCp=676 K) and RUS measurements (Θelastic=688 K).
Numerical investigation of multiple droplet growth dynamics on a solid surface using three-dimensional lattice Boltzmann simulations
Authors: Pawar Nilesh D. , Bahga Supreet Singh , Kale Sunil R. , Kondaraju Sasidhar
Published: April 2021

We present an investigation of multiple droplet growth dynamics on homogeneous and patterned surfaces during dropwise condensation. Our analysis is based on three-dimensional thermal lattice Boltzmann simulations. First, we investigate the growth dynamics on homogeneous surfaces. The analysis of growth dynamics of droplets on a homogeneous surface shows that the lower the static contact angle of the surface, the higher the condensed volume of liquid. After that, we discuss the growth dynamics of droplets on patterned surfaces (a surface with hydrophilic and hydrophobic regions). We show that the pattern formed by the condensed droplets on the patterned surfaces is completely different from the homogeneous surface. This is due to the pinning effect at the interface of the hydrophilic–hydrophobic region. Moreover, the shape of the droplets is not spherical, as we observe in the case of homogeneous surfaces. We also demonstrate that the condensed volume V for all patterned surfaces is higher than that for the homogeneous surface. However, the condensed volume decreases with an increase in the contact angle of the hydrophilic region. We then present the effect of size of the hydrophilic spot. We find that the condensed volume increases with an increase in radius of the hydrophilic spot.
Quantitative study on the influence of the difference of the molecular structure on the spontaneous combustion characteristics of the coal metamorphism process
Authors: Dai Fengwei , Zhang Huiwen
Published: April 2021

Neimeng lignite, Huajin bituminous coal, Sitai bituminous coal, and Changcun lean coal with different degrees of metamorphism were analyzed via infrared spectrum curve fitting analysis and thermal analysis experiments, and the influence of the change in the active functional groups in the coal structure on the coal spontaneous combustion characteristics was explored. After the spectral curve was fitted, it could be divided into four areas—hydroxyl, C–H stretch band, oxygen-containing functional group, and aromatic structure—and then, the molecular structure content of different functional groups was quantitatively calculated. In the thermal analysis experiment, the characteristic value and the combustion activation energy of the coal were obtained through the thermogravimetric analysis curve, and the calorific value of the coal could be calculated using the differential scanning calorimetry curve. After combining the two experiments to obtain a linear relationship, the results showed that as the degree of coal metamorphism deepened, the activation energy of the coal combustion gradually increased, and the amount of heat released decreased. For the self-associated hydroxyl group in the hydroxyl group, the methylene group in the aliphatic hydrocarbon, the C=C double bond in the oxygen-containing functional group, and the three-substituted aromatic ring in the aromatic structure, the content of these functional groups is the highest for coal, with increases of 11.01%, 31.81%, 14.34%, and 22.9%, respectively, and the effect of inhibiting the spontaneous combustion of coal is more significant.
Near-infrared stimulated emission from indium-rich InGaN layers grown by plasma-assisted MBE
Authors: Lobanov D. N. , Kudryavtsev K. E. , Kalinnikov M. I. , Krasilnikova L. V. , Yunin P. A. , Skorokhodov E. V. , Shaleev M. V. , Novikov A. V. , Andreev B. A. , Krasilnik Z. F.
Published: April 2021

We report on the stimulated emission (SE) in the near-infrared range from the planar InGaN epitaxial layers grown on sapphire substrates. By varying the indium content from 100% to 75%, the emission wavelength is tunable from 1.65 to 1.1 μm and minimum threshold intensities of 20–30 kW/cm2 at T = 77 K were obtained for layers with an 80%–90% indium fraction emitting around 1.3 μm. We suggest that at low temperatures, limitations for observation of SE from heavily doped InN and InGaN layers are mostly imposed by strong losses due to free-carrier absorption approaching material gain at residual electron concentrations in excess of several 1019 cm−3 and not directly by Auger recombination of non-equilibrium charge carriers. At higher temperatures, Shockley–Read–Hall (SRH) recombination sets on as a dominant nonradiative process, which determines temperature quenching of stimulated emission at Tmax ∼ 190–210 K in a way very similar to that observed earlier for InN layers with a much lower background doping level of about 3 × 1017 cm−3. Thus, different defect centers are expected to provide free electrons for InN and InGaN layers under consideration and to contribute to the SRH recombination rate, which affects SE at high temperatures.
A close coupling study of the bending relaxation of H2O by collision with He
Authors: Stoecklin Thierry , Cabrera-González Lisán David , Denis-Alpizar Otoniel , Páez-Hernández Dayán
Published: April 2021

We present a close coupling study of the bending relaxation of H2O by collision with He, taking explicitly into account the bending–rotation coupling within the rigid-bender close-coupling method. A 4D potential energy surface is developed based on a large grid of ab initio points calculated at the coupled-cluster single double triple level of theory. The bound states energies of the He–H2O complex are computed and found to be in excellent agreement with previous theoretical calculations. The dynamics results also compare very well with the rigid-rotor results available in the Basecol database and with experimental data for both rotational transitions and bending relaxation. The bending–rotation coupling is also demonstrated to be very efficient in increasing bending relaxation when the rotational excitation of H2O increases.
A quantum mechanical model of electron field emission from two dimensional materials. Application to graphene
Authors: Lepetit Bruno
Published: April 2021

We implement a new time-independent perturbative quantum method to study quantitatively electron field emission from two dimensional materials and, in particular, from graphene. The Bardeen transfer Hamiltonian formalism is coupled to a detailed description of the electronic structure of the material. This calculation method is first validated on the standard Fowler–Nordheim (FN) model of a three-dimensional (3D) free-electron gas. Then, it is used to study emission from a two-dimensional (2D) free-electron gas and from graphene represented by a tight-binding model. In the case of graphene, we show that a full electronic band model of the material is necessary to obtain reasonable results because emission is not restricted to the vicinity of the Fermi level near the Dirac points. The graphene emitted current density follows a modified FN law with respect to the applied field, with a prefactor exponent for the field n≈1.5 intermediate between the one for the cases of 2D (n=0) and 3D (n=2) free-electron gases. However, the emitted current level is low because the kinetic energy of the electrons corresponds to a motion parallel to the emitting surface, which is not efficient in promoting emission. Our study gives a firm ground to the idea that emission from graphene results almost exclusively from defects.
AC/DC dual-mode magnetoelectric sensor with high magnetic field resolution and broad operating bandwidth
Authors: Li Jinming , Ma Guoqiang , Zhang Shouheng , Wang Chunmei , Jin Zhejun , Zong Weihua , Zhao Guoxia , Wang Xia , Xu Jie , Cao Derang , Li Shandong
Published: April 2021

In this study, a dual-mode Metglas/Pb(Zr,Ti)O3 magnetoelectric (ME) sensor was prepared for measuring weak magnetic fields. It is interesting to note that this ME sensor can work at alternating current (AC) and direct current (DC) dual-modes with high field resolution. In AC mode, a very accurate AC magnetic field resolution of 0.8 nT was achieved at a mechanical resonance frequency of 72.2 kHz; moreover, the operating frequency band for resolution better than 1 nT is as wide as 3.4 kHz. We proposed a DC bias field perturbation (DBFP) method to detect the DC magnetic field using lock-in amplifier technology. As a result, an ultra-accurate DC field resolution of 0.9 nT with noise power spectral density as low as 100 pT/Hz was obtained in the studied ME sensor via the DBFP method. The dual-mode ME sensor enables simultaneous measurement for DC and AC magnetic fields with wideband and accurate field resolution, which greatly enhances the measurement flexibility and application scope.
Long-term and short-term immunity to SARS-CoV-2: why it matters
Authors: Zaunders John , Phetsouphanh Chansavath
Published: April 2021

The adaptive immune system, regulated by CD4 T cells, is essential for control of many viral infections. Endemic coronavirus infections generally occur as short-term upper respiratory tract infections which in many cases appear to be cleared before adaptive immunity is fully involved, since adaptive immunity takes approximately 1.5–2 weeks to ramp up the response to a primary infection, or approximately 1 week for a recurrent infection. However, the adaptive immune response to SARS-CoV-2 infection will be critical to full recovery with minimal long-lasting effects, and to either prevention of recurrence of infection or at least reduced severity of symptoms. The detailed kinetics of this infection versus the dynamics of the immune response, including in vaccinated individuals, will largely determine these outcomes.
The role of lateral erosion in the evolution of nondendritic drainage networks to dendricity and the persistence of dynamic networks
Authors: Kwang Jeffrey S. , Langston Abigail L. , Parker Gary
Published: April 2021

Significance

Most of Earth’s landscapes are dissected by rivers, which are important for providing water, food, and energy resources. From remote imaging, we see that rivers organize themselves into dendritic (tree-like) networks. The shape and organization of river networks determine how and where water and sediment are routed on Earth. To date, models of river network formation, named landscape evolution models, are unable to explain how nondendritic networks evolve into strongly branching systems. Here, we capture this evolution utilizing a model that incorporates how rivers erode in the lateral direction.
Sensitivity to geometric shape regularity in humans and baboons: A putative signature of human singularity
Authors: Sablé-Meyer Mathias , Fagot Joël , Caparos Serge , van Kerkoerle Timo , Amalric Marie , Dehaene Stanislas
Published: April 2021

Significance

Determining the cognitive differences between human and nonhuman primates is a central goal of cognitive neuroscience. We show that intuitions of geometry are present in humans but absent in baboons. A simple intruder task in which subjects must find which of six geometric shapes is different reveals an effect of geometric regularity in all human groups regardless of age, education, and culture, yet this effect is absent in baboons. Models of the ventral visual pathway for object recognition predict baboons’ performance, but a symbolic model is needed to account for human performance. Our results underline the human propensity for symbolic abstraction, even in an elementary shape perception task, and provide a challenge for neural network models of human shape perception.