bluuebunny/crossref_metadata_2025 huggingface dataset:
Silicon Carbide Power Module Co-Designed for Enhanced Thermal and Electrical Performance in Steady State and Transient Conditions
Authors: Gowda Arun V. , Miorini Rinaldo L. , Fish Michael , Sharar Darin J. , deBock Peter
Published: December 2020

The demand for high power density, therefore high heat dissipation, silicon carbide power electronics modules is propelled by applications such as hybrid transportation and renewable power generation and conversion, among others. Besides a low thermal resistance, these applications require high thermal capacitance to manage transient operations.

The Package Integrated Cyclone COoler (PICCO) is an additively manufactured, thermal energy storing cooler codesigned by GE Research (GRC) in collaboration with the US Army Research Lab (ARL). The key aspect of PICCO is its capability to swirl a two-phase coolant, i.e. liquid-gas. The centrifugal field creates a radial pressure gradient inducing buoyancy. The strong radial acceleration to which the fluid is subject forces relatively cold flow outward to reach the hot wall, thus boosting the heat transfer, while hot flow and bubbles migrate inward and the two-phase system is nearly isothermal (thermal storage).

In this paper, we introduce a novel power module package which brings together silicon carbide devices, Power OverLay (POL) wirebondless interconnect, and two-phase swirling flow in an additively manufactured cooler. Various embodiments of this power module structure are presented along with a discussion on their thermal behavior when subjected to a hybrid vehicle drive cycle.
Evolution of Anand Parameters With Elevated Temperature Aging for SAC Leadfree Alloys
Authors: Lall Pradeep , Yadav Vikas , Suhling Jeff , Locker David
Published: December 2020

Electronic equipment in automotive, agricultural and avionics applications may be subjected to temperatures in the range of −55 to 200°C during storage, operation and handling in addition to high strain-rates. Strain rates in owing to vibration and shock may range from 1–100 per sec. Temperature in electronic assemblies depends typically on location, energy dissipation and thermal architecture. Some investigators have indicated that the required operating temperature is between −40 to 200°C for automotive electronics located underhood, on engine, on transmission. Prior data indicates the evolution of mechanical properties under extended exposures to high temperatures. However, the constitutive models are often only available for pristine materials only. In this paper, effect of low operating temperatures (−65°C to 0°C) on Anand-model parameters at high strain rates (10–75 per sec) for aged SAC (SAC105 and SAC-Q) solder alloys has been studied. Stress-Strain curves have been obtained at low operating temperatures using tensile tests. The SAC leadfree solder samples were subjected to isothermal-aged up to 4-months at 50°C before testing. Anand Viscoplastic model has been used to describe the material constitutive behavior. Evolution of Anand Model parameters for SAC solder has been investigated. The computed parameters of the experimental data were used to simulate the tensile test and verified the accuracy of the model. A good correlation was found between experimental data and Anand predicted data.
Degradation Mechanisms of Underfills Subjected to Isothermal Long-Term Aging From 150°C to 200°C
Authors: Lall Pradeep , Zhang Yunli , Wu Haotian , Davis Ed , Suhling Jeff
Published: December 2020

FCBGAs are finding applications in automotive underhood environments where they may be subjected to sustained temperatures of 125–200°C for sustained periods during operation. While, FCGBAs have been previously used in consumer applications where operating temperatures typically range in 55–85°C, relatively little is known on methods to design damage-tolerant packages in automotive underhood environments. There is insufficient information on plastic encapsulated electronic components capable of surviving high temperatures for long periods (> 100,000 hours). In this paper, four different types of underfills has been cured and aged. Mechanical tests have been performed on all the four types of underfills too understand the degradation in properties under extended high temperature operation. Uniaxial tensile tests are conducted to study the elastic modulus, ultimate tensile strength and percentage elongation of the underfills. After uniaxial tensile tests, Optical Microscope, SEM and EDS are applied to study the microstructure behaviors of the cross-section area of the underfills. The experimental results are compared before and after aging tests, including pristine, 30 days, 60 days, 90days, 120 days and 240 days. The research focuses on microstructure-property-processing-performance relationships, building the relation between the microstructure evolution and macro-mechanical properties. Reliability physics of high temperature degradation of packaging material is studied.
Study of Lead Free Solder Joints Subjected to Isothermal Mechanical Shear Cycling
Authors: Hoque Mohd Aminul , Haq Mohammad Ashraful , Suhling Jeffrey C. , Lall Pradeep
Published: December 2020

Electronic packages are usually subjected to varying temperature conditions, thus subjecting the package to thermal cyclic loadings. As the different components of the package are made up of materials of different Coefficients of Thermal Expansion (CTE), the thermal cyclic loading brings about fluctuating shear stress to arise within the package, ultimately leading to its failure. It has been seen in previous literature that the recrystallization assisted cracking is a major factor that leads to the failure of solder joints when subjected to thermomechanical cycles. In this study, the authors have tried to determine whether the mechanical shear cycling of aged and non-aged samples of SAC305 lead free solder joints undergo a recrystallization phase before its ultimate failure. Arrays (3 × 3) of SAC305 solder joints of roughly 750μm in diameter were reflowed in between two FR-4 printed circuit boards to create a sandwiched structural sample. The samples were then polished to expose the solder joints. A polarized light microscope was utilized to capture the images of the joints before and after the mechanical cycling and analyzed to observe any changes in the microstructure in the form of recrystallization of the tin grains.
Molecular Dynamics Investigation of Water Behavior Through Nanopores
Authors: Montazeri Kimia , Cao Penghui , Won Yoonjin
Published: December 2020

The transport of fluids through nanoscale pores, channels, and membranes has been of great importance in our daily life. Nanoscale transport is relevant to many applications such as agriculture, energy and environmental fields. Considering these applications, it is important to characterize detailed mechanisms of liquid transport through nanoscale defects and pores on surfaces. Such characterization requires a detailed understanding of the deviation of water behavior and its transport mechanisms in nanoscale from bulk water. Molecular dynamics provide proper means to understand the dynamics and mechanisms of motions of water molecules confined in ultra-small spaces. This work examines the water transport through an individual pore which has a nanoscale dimensions ranging from 1.0 to 1.8 nm from molecular dynamics perspective. The effects of the nanopore dimensions as well as the surface wetting properties on the behavior of confined water are studied. The translational and rotational dynamics of water molecules are characterized by examining velocity autocorrelation functions and the calculation of the density of states, which supports the presence of unusual, solid-like behaviors of water molecules. A good understanding of the transport mechanisms and their origins are crucial to address common challenges in many engineering applications such as energy storage and conversion and could pave the way towards more efficient water-energy systems.
WFUMB position paper on reverberation artefacts in lung ultrasound: B-lines or comet-tails?
Authors: Mathis Gebhard , Horn Rudolf , Morf Susanne , Prosch Helmut , Rovida Serena , Soldati Gino , Hoffmann Beatrice , Blaivas Michael , Dietrich Christoph F.
Published: December 2020

The analysis of vertical reverberation artefacts is an essential component of the differential diagnosis in pulmonary ultra-sound. Traditionally, they are often, but not exclusively, called B-line artefacts (BLA) and/or comet tail artefacts (CTA), but this view is misleading. In this position paper we clarify the terminology and relation of the two lung reverberation artefacts BLA and CTA to spe-cific clinical scenarios. BLA are defined by a normal pleura line and are a typical hallmark of cardiogenic pulmonary edema after exclusion of certain pathologies including pneumonia or lung contusion, whereas CTAs show an irregular pleura line representing a variety of parenchymal lung diseases. The dual approach using low frequency transducers to determine BLA and high frequency transducer to determine the pleural surface is recommended.
Structure of oceanic crust in back-arc basins modulated by mantle source heterogeneity
Authors: Grevemeyer Ingo , Kodaira Shuichi , Fujie Gou , Takahashi Narumi
Published: December 2020

Subduction zones may develop submarine spreading centers that occur on the overriding plate behind the volcanic arc. In these back-arc settings, the subducting slab controls the pattern of mantle advection and may entrain hydrous melts from the volcanic arc or slab into the melting region of the spreading ridge. We recorded seismic data across the Western Mariana Ridge (WMR, northwestern Pacific Ocean), a remnant island arc with back-arc basins on either side. Its margins and both basins show distinctly different crustal structure. Crust to the west of the WMR, in the Parece Vela Basin, is 4–5 km thick, and the lower crust indicates seismic P-wave velocities of 6.5–6.8 km/s. To the east of the WMR, in the Mariana Trough Basin, the crust is ∼7 km thick, and the lower crust supports seismic velocities of 7.2–7.4 km/s. This structural diversity is corroborated by seismic data from other back-arc basins, arguing that a chemically diverse and heterogeneous mantle, which may differ from a normal mid-ocean-ridge–type mantle source, controls the amount of melting in back-arc basins. Mantle heterogeneity might not be solely controlled by entrainment of hydrous melt, but also by cold or depleted mantle invading the back-arc while a subduction zone reconfigures. Crust formed in back-arc basins may therefore differ in thickness and velocity structure from normal oceanic crust.
Supplemental Material: Fault kinematics: A record of tectono-climatically controlled sedimentation along passive margins, an example from the U.S. Gulf of Mexico
Authors: Omale Abah P. , al. et
Published: December 2020

Details on well log cross sections, seismic cross section, and LiDAR images within the study area.
Para-aortic haemangioma mimics paraganglioma on MRI
Authors: Flores Hunter , Popat Shreeya , Mayer Wesley A , Link Richard E
Published: December 2020

Here, we report a case of a 70-year-old man referred for an incidentally discovered left renal lesion with peri-aortic lymphadenopathy following a CT scan for back pain. A follow-up MRI scan demonstrated a Bosniak IIF left renal cyst and a T2-hyperintense para-aortic lesion concerning for extra-adrenal paraganglioma (EAP). [131I] Metaiodobenzylguanidine scintigraphy of the para-aortic lesion and urine catecholamines were equivocal. The mass was resected via a robotic approach. Histological examination revealed a haemangioma. Haemangiomas are benign vascular tumours frequently identified on imaging of the liver. Intra-abdominal haemangiomas outside of the liver, however, are rare and may have imaging characteristics that mimic EAP.
Langerhans cell histiocytosis in the occipital condyle: a case study and a brief review of the literature
Authors: Barbosa Nuno Cesar , Ramos Acacio , Sagarribay Amets , Ribeiro Maria José
Published: December 2020

We present a case study of a 5-year-old patient, who presented with left-sided torticollis. Due to persistence of problems, a CT and an MRI were made showing a single osteolytic lesion centred on right occipital condyle. After an open biopsy, histology confirmed it to be Langerhans cell histiocytosis (LCH). Torticollis or restricted range of motion is a presenting feature in 76% of children with LCH with cervical involvement. There remains much debate on the best treatment strategy. The clinical and radiological outcomes of the case study presented on this article support the treatment of LCH with chemotherapy in cases with solitary involvement of the occipital condyle.
Efficacy of antiviral therapy in patients with post-hepatitis C liver cirrhosis: is hyperuricaemia a potential adverse effect?
Authors: Elsayed Amr , M Abdelraheem Ehab , Hassan Hatem , Abbas Abbas , Hassnine Alshymaa
Published: December 2020

Hepatitis C virus (HCV) related liver cirrhosis is considered a major health problem; sofosbuvir (SOF)/ledipasvir (LDV) and SOF/daclatsvir (DACLA) are very promising direct antiviral agents (DAAS) especially in treating HCV genotype 4 which is the main genotype in Egypt. Uric acid elevation was reported in many systemic diseases and might be elevated during direct antiviral therapy. The aim is to evaluate efficacy and safety of SOF/LDV and SOF/DACLA plus ribavirin in treating HCV related child A liver cirrhosis and assess hyperuricaemia as a potential adverse effect to this regimen.

Methods

This prospective observatinal study included 128 HCV naive child A cirrhotic patients divided into two groups (77 patients were treated with SOF 400 mg, DACLA 60 mg and ribavirin 600 mg and 51 patients were treated with SOF 400 mg, LDV 90 mg and ribavirin 600 mg) for 12 weeks, during the treatment complete blood count, creatinine, bilirubin, alanine transaminase, aspartate transaminase and serum uric acid were monitored, HCV RNA quantitative PCR at 12 weeks after the end of treatment was done.

Results

Response to treatment in SOF/LDV (sof/led) group is about (98%), response to treatment in SOF/DACLA (sof/dacla) group is about (96%). Hyperuricaemia was noticed in 17.6% of patients received sof/led and in 15.5% of those received sof/dacla.

Conclusion

SOF+LDV and SOF+DACLA plus ribavirin regimens are highly effective in treating chronic HCV patients with compensated liver cirrhosis. Hyperuricaemia is considered a potential adverse effect to DAAS containing ribavirin and may lead to serious side effects such as renal impairment.
Genetic variants for personalised management of very low carbohydrate ketogenic diets
Authors: Aronica Lucia , Volek Jeff , Poff Angela , D'agostino Dominic P
Published: December 2020

The ketogenic diet (KD) is a low-carbohydrate, high-fat, adequate-protein diet proven to be effective for the reversal of obesity, metabolic syndrome and type 2 diabetes, and holding therapeutic potential for the prevention and treatment of other chronic diseases. Genetic and dynamic markers of KD response may help to identify individuals most likely to benefit from KD and point to individuals at higher risk for adverse health outcomes. Here, we provide a clinician-friendly review of state-of-the-art research on biomarkers of KD response for a variety of outcomes including weight loss, body composition and cognitive performance drawing data from both intervention trials and case reports of rare inborn errors of metabolism. We also present a selection of the most promising candidate genes to evaluate in future studies and discuss key aspects of study design and variant interpretation that may help accelerate the implementation of these biomarkers in clinical practice.
Death rounds to support critical care nurses: a qualitative study
Authors: Ong Keh Kiong , Sum Chew Lai , Zhou Xuelian Jamie , Chow Yeow Leng
Published: December 2020

Objective

Providing end-of-life care has a significant psychological impact on critical care nurses. Little is known about whether critical care nurses find death rounds useful as a support system. This study aimed to describe critical care nurses’ perceptions of attending death rounds.

Methods

This study was conducted using a qualitative descriptive design, using one-to-one audio-recorded interviews. The study was conducted at a 20-bed medical intensive care unit in a 1200-bed public tertiary hospital in Singapore. One-to-one interviews were conducted with 14 nurses using a semi-structured interview guide. Data was analysed using thematic analysis.

Results

Critical care nurses valued attending death rounds. They found death rounds to be an outlet to express themselves and remember patients, to draw and give peer support, to build nursing and interprofessional cohesiveness and to learn to improve palliative care. The death rounds were optimal when they felt safe to share, when there was a good facilitator, when the hierarchy was flat and when the audience was interdisciplinary. The barriers to a successful death round were the rounds being too formal, timing and not knowing the patients.

Conclusion

Death rounds are a viable way to support critical care nurses in providing end-of-life care.
Bacterial O-GlcNAcase genes abundance decreases in ulcerative colitis patients and its administration ameliorates colitis in mice
Authors: He Xiaolong , Gao Jie , Peng Liang , Hu Tongtong , Wan Yu , Zhou Meijuan , Zhen Peilin , Cao Hong
Published: December 2020

Objective

O-linked N-acetylglucosaminylation (O-GlcNAcylation), controlled by O-GlcNAcase (OGA) and O-GlcNAc transferase (OGT), is an important post-translational modification of eukaryotic proteins and plays an essential role in regulating gut inflammation. Gut microbiota encode various enzymes involved in O-GlcNAcylation. However, the characteristics, abundance and function of these enzymes are unknown.

Design

We first investigated the structure and taxonomic distribution of bacterial OGAs and OGTs. Then, we performed metagenomic analysis to explore the OGA genes abundance in health samples and different diseases. Finally, we employed in vitro and in vivo experiments to determine the effects and mechanisms of bacterial OGAs to hydrolyse O-GlcNAcylated proteins in host cells and suppress inflammatory response in the gut.

Results

We found OGAs, instead of OGTs, are enriched in Bacteroidetes and Firmicutes, the major bacterial divisions in the human gut. Most bacterial OGAs are secreted enzymes with the same conserved catalytic domain as human OGAs. A pooled analysis on 1999 metagenomic samples encompassed six diseases revealed that bacterial OGA genes were conserved in healthy human gut with high abundance, and reduced exclusively in ulcerative colitis. In vitro studies showed that bacterial OGAs could hydrolyse O-GlcNAcylated proteins in host cells, including O-GlcNAcylated NF-κB-p65 subunit, which is important for activating NF-κB signalling. In vivo studies demonstrated that gut bacteria-derived OGAs could protect mice from chemically induced colonic inflammation through hydrolysing O-GlcNAcylated proteins.

Conclusion

Our results reveal a previously unrecognised enzymatic activity by which gut microbiota influence intestinal physiology and highlight bacterial OGAs as a promising therapeutic strategy in colonic inflammation.
Gravitational wave signatures of highly magnetized neutron stars
Authors: Flores Cesar V. , Lopes Luiz L. , Castro Luis B. , Menezes Débora P.
Published: December 2020

Motivated by the recent gravitational wave detection by the LIGO–VIRGO observatories, we study the Love number and dimensionless tidal polarizability of highly magnetized stars. We also investigate the fundamental quasi-normal mode of neutron stars subject to high magnetic fields. To perform our calculations we use the chaotic field approximation and consider both nucleonic and hyperonic stars. As far as the fundamental mode is concerned, we conclude that the role played by the constitution of the stars is far more relevant than the intensity of the magnetic field, and if massive stars are considered, the ones constituted by nucleons only present frequencies somewhat lower than the ones with hyperonic cores. This feature that can be used to point out the real internal structure of neutron stars. Moreover, our studies clearly indicate that strong magnetic fields play a crucial role in the deformability of low mass neutron stars, with possible consequences on the interpretation of the detected gravitational waves signatures.
Extended multi-scalar field theories in $$(1+1)$$ dimensions
Authors: Aguirre A. R. , Souza E. S.
Published: December 2020

We present the explicit construction of some multi-scalar field theories in$$(1+1$$(1+1) dimensions supporting BPS (Bogomol’nyi–Prasad–Sommerfield) kink solutions. The construction is based on the ideas of the so-called extension method. In particular, several new interesting two-scalar and three-scalar field theories are explicitly constructed from non-trivial couplings between well-known one-scalar field theories. The BPS solutions of the original one-field systems will be also BPS solutions of the multi-scalar system by construction, and therefore we will analyse their linear stability properties for the constructed models.
Normal forms in braid groups with respect to some Gröbner–Shirshov basis
Authors: Chen Xing , Zhao Xuezhi
Published: December 2020

In 2008, Bokut obtained a Gröbner–Shirshov basis [Formula: see text] of the braid group [Formula: see text] in the Artin–Garside generators and showed that [Formula: see text]-irreducible words of the [Formula: see text] coincided with the Garside normal forms of words. Using this basis [Formula: see text], we obtain the concrete expression of the [Formula: see text]-irreducible words, i.e. normal forms, of the [Formula: see text], and hence give a new understanding of the word problem and Garside normal forms of braid groups.
On the consistency of jump-diffusion dynamics for FX rates under inversion
Authors: Graceffa Federico , Brigo Damiano , Pallavicini Andrea
Published: December 2020

We investigate the consistency under inversion of jump diffusion processes in the foreign exchange market. That is, if the EUR/USD exchange rate follows a given type of dynamics, under which conditions will USD/EUR follow the same type of dynamics? After giving a numerical description of this property, we establish a suitable local volatility structure ensuring consistency. We subsequently introduce jumps and analyze both constant and random jump size. While in the first scenario consistency is automatically satisfied, the second case is more involved. A fairly general class of admissible densities for the jump size in the domestic measure is determined.
Flame Retardant Additive Influence on Negative Electrode for Lithium Ion Accumulators
Authors: Maca Josef , Libich Jiri , Kazda Tomas , Jasso Kamil
Published: December 2020

Almost every person is using batteries on daily base. From small appliances to larger power tools to large stores and electric cars. Requirements for lithium ion batteries getting higher every year either from view of capacity, cycle number, or high current flow. With higher requirements is also the safety of batteries connected. Lithium ion batteries need to work safely and reliably at higher temperatures and loads. From flame safety view is necessary non-flammability of all battery parts. One of potential risk is organic solvents based electrolyte. This paper focus on influence, of flame-retardant additive in electrolyte, and its compatibility with the negative electrode in lithium ion battery. Several phosphorous-based flame retardants were tested and their influence on capacity of negative electrode was determined.
Characterization Investigation of Lithium-Ion Battery Cells
Authors: Madani Seyed Saeed
Published: December 2020

This section studies the performance behavior of a lithium titanate oxide-based battery cell at different working conditions. Battery cell performance analysis was put into research appertaining to comprehensive experimental laboratory measurements. Different load profiles were applied to the lithium titanate oxide-based battery. To assess the performance of the lithium titanate oxide-based battery cell, extensive laboratory characterization experiments were accomplished.
Solid Polymer Electrolytes and Modified Electrodes are Basis for New Generation of High-Energy Lithium Batteries
Authors: Shembel Elena , Chervakov Oleg , Markevych Alexander , Kolomoiets Olha , Redko Volodymyr , Polishchuk Yuliya , Zaderey Nellya , Pysny Vasiliy , Koltsov Nikolay
Published: December 2020

Results of investigation, developing, manufacturing, and test/evaluation of the experimental samples of innovating lithium batteries with solid polymer electrolyte and Li metal will be illustrated in this presentation and the following article. Innovating lithium batteries combine the following: 1) anode based on lithium or lithium alloys (instead of anode that are based on carbon materials); 2) solid polymer electrolytes with performance in operating temperatures range of battery from minus 30oC and up to plus 120oC; and 3) cathode, which is based on modified lithium manganese spinel. Innovating solid polymer electrolyte is modified using ionic liquids. Cathode based on LiMn2O4, which has been synthesized using Ukrainian manganese ores.
A State of Art Critical Review on Advancement in MXenes for Electrochemical Energy Storage in the View of Interlayer Spacing
Authors: Thakur Amrit Kumar , Hwang Jang-Yeon , Sathyamurthy Ravishankar
Published: December 2020

MXenes, the fascinating 2-D material derived from transition metal carbide and nitride, have received significant attention in electrochemical energy storage owing to its superior conductivity, hydrophilicity, larger specific surface area, and structural topology. Numerous theoretical and experimental studies have extensively discussed its huge potential for electrochemical energy storage. In this view, we summarized the latest advancement in preparation and storage capacity of MXenes with major focus on the interlayer spacing. We begin by studying the structure topology and the preparation methods of MXenes, where different etchants such as HCl, LiF, and HF were used to etch ‘A’ element from the MAX phases. The review then extensively discusses the adjustable interlayer spacing through pre-pillaring and final pillared technology. Finally, the conclusion and viewpoint is presented with the further applications areas of MXenes.
Nanocrystalline TiO2 and Li4Ti5O12 as Novel Inorganic Host Materials for Li-S Batteries
Authors: Zukalova Marketa , Kavan Ladislav
Published: December 2020

Composites of sulfur with nanocrystalline TiO2, Li4Ti5O12, and carbon were prepared by melting diffusion and characterized by X-ray diffraction, Raman spectroscopy, and cyclic voltammetry. XRD analysis was hindered by overlap of the majority of diagnostic peaks of TiO2 with diffraction peaks of sulfur. Raman spectroscopy indicates strong attenuation of sulfur-related modes, if S is encapsulated in porous carbonaceous material or coated with conductive carbonaceous additive in thin film electrode. In turn, this effect proves perfect accommodation of S inside pores of the carbonaceous skeleton. The best electrochemical performance of a composite of nanocrystalline TiO2 with sulfur was ascribed to large surface area of the host enabling even coverage of its surface by adsorbed sulfur. TiCl4 post treatment had negative effect on electrochemical performance of modified electrodes.
Binder Influence on Electrochemical Properties of Li-S Batteries
Authors: Capkova Dominika , Kazda Tomas , Čudek Pavel , Strakova Fedorkova Andrea
Published: December 2020

Demand for clean and efficient energy storage is constantly growing due to concerns about limited global energy supply, environmental and climate change. Batteries with expected energy density values in the range of several hundred watts per kilogram are currently receiving special attention. One of the most common examples of high-energy batteries are lithium-sulfur batteries and they may replace Li-ion batteries in their applications. Sulfur has the advantages of low price, natural affluence, and compatibility with nature. However, several shortcomings of this technology need to be solved before commercialization. By using a suitable binder in the production of the positive electrodes, some of them could be repressed.
Development of Recycling of Photovoltaic Systems from the Point of View of Prolonging the Total Service Life of Photovoltaic Modules and Circular Energetic
Authors: Vanek Jiri , Maule Petr , Jandová Kristyna
Published: December 2020

The work aims to analyze and evaluate the extension of the overall life of photovoltaic systems in relation to the need for quality recycling or the possibility of secondary reuse. Although not all components of photovoltaic systems are currently balanced in terms of life expectancy, the future goal of the designers of these systems will be to create a comprehensive, long-life system, including hybrid inverters and batteries.
Corrosion Resistance of Plasma Nitrided Austenitic Stainless Steel AISI 304 (X5CrNi18-10)
Authors: Kusmič David , Cech Ondrej , Klakurková Lenka
Published: December 2020

In this paper, austenitic stainless steel AISI 304 (X5CrNi 18-10) has been subjected to low-temperature plasma nitriding (LTPN) at 400°C (673 K) in 24H2:8N2 (l/h), and in 8H2:24N2 (l/h) marked as LTPN-R, and to high-temperature plasma nitriding (HTPN) at 550°C (823 K) in 24H2:8N2 (l/h) working atmosphere, for 15h. The microstructure, microhardness, and phase evaluation of the nitrided steel were studied. The PN led to significant microhardness increase from 206 ± 3 HV0.05 to 842 ± 27 HV0.05 (LTPN), 821 ± 18 HV0.05 (LTPN-R), resp. to 1246 ± 27 HV0.05 (HTPN). The corrosion properties were evaluated using the anodic potentiodynamic polarization tests in neutral 2.5% NaCl deaerated solution. The corrosion rate CR (mm.a-1) increased only slightly for LTPN procedures. But using the HTPN increased 43-times to untreated steel, due to reduced passivation ability by chromium depletion by formed CrN. Additionally, the pitting was evaluated, and the pitting coefficient was calculated.
Iron-Magnesium Materials for Biodegradable Implants Prepared by Powder Metallurgy
Authors: Sedlarikova Marie , Mika Martin , Hrabovsky Jiri , Tkacova Tereza , Fafilek Guenter , Cudek Pavel
Published: December 2020

The preparation of metal components by a modified powder technology was tested. Iron and magnesium powders are used for the manufacturing of objects of arbitrary form. Its final treatment was in nitrogen atmosphere at 1120°C.
Adhesion of PVD Coatings on Surface of Small Arm
Authors: Joska Zdenek , Rak Ludek , Daniel Josef , Horníček Jakub , Tříska Václav , Nguyen Chien Huu
Published: December 2020

This work deals with the possibility of increasing the utility properties of the functional part of the weapon by deposition of PVD coating. These coatings are widely known for their high hardness and abrasion resistance without affecting the anti-corrosion properties. The experimental part evaluates the created duplex coating on the piston of the assault rifle Sa vz. 58. Duplex coating adhesion, surface morphology, and coating thickness was evaluated on opto digital microscope Olympus DSX 500. The impact resistance of the coating was evaluated by dynamic impact test. The durability tests of the coatings were carried out during the training of students in the military training. The results showed the application of PVD coating significantly reduced piston head wear and increased user comfort in the form of shortening time of the cleaning and maintenance process after firing.
Change of Geometric Accuracy of Structural Steels after Carburizing in Gas
Authors: Dobrocky David , Pokorny Zdenek , Joska Zdenek , Studeny Zbynek , Prochazka Jiri , Svoboda Emil , Dostal Petr
Published: December 2020

Nowadays, carburizing at low pressure or vacuum carburizing is often used, which is a modification of carburizing in gas, while carburization is performed at pressures well below the level of atmospheric pressure (101 kPa). The advantage of this process is that no internal oxidation occurs; carburizing has a higher rate and uniformity of carburization, good reproducibility of the process and lower deformation. Carburizing is mainly used for parts subjected to abrasion (eg gears). However, even with this process, the geometric accuracy and surface texture of the parts change. The changes of geometric accuracy of ground samples from carbon steel C45, low-alloy Mn-Cr carburizing steel 16MnCr5 and medium-alloyed Ni-Cr carburizing steel 14NiCr14, which were vacuum-carburized in a CO/CH4 atmosphere, were evaluated in this work. Geometric accuracy was evaluated by measurement using a 3D coordinate measuring machine, surface texture using a coherent correlation interferometer. After the carburizing process, changes in the dimensions of the samples were found in all steels. For C45 steel, the sample dimensions were reduced by 0.028 mm ± 0.004 mm, the surface roughness expressed by the parameter Ra decreased by 0.28 µm, which is 20%. In case of carburizing steels there was an increase in the dimensions of the samples, especially in the case of 14NiCr14 steel and a smaller difference in surface roughness. The same parameters of the carburizing process lead to different behaviour of carburized parts in different steels, in terms of changes in dimensions and surface texture.
Compact Battery Power Source for Oscilloscope
Authors: Martiš Jan , Vorel Pavel , Lažek Tomáš
Published: December 2020

A battery DC power source for a small oscilloscope was designed and constructed. Its output voltage is ca. 300 V and its output power is about 60 W. A series-resonant DC/DC converter with a pulse transformer is the core of this device. The source is supplied from a Li-ion battery with nominal voltage of ca 3.6 V (several cells connected in parallel). It is often necessary in power electronics measurements to have a galvanically separated supplying of the oscilloscope. A mains power supply with low parasitic capacitance is sometimes used but for some special measurements even this small capacitance (e.g., 50 pF) is too high. The battery supplied power source can achieve a lower capacitance. Certainly the possibility to use the oscilloscope without available mains power is advantageous.
The Impact of Pumping Velocity on Temperature Running in Chambers of Experimental System
Authors: Maxová Anna , Maxa Jiří , Šabacká Pavla
Published: December 2020

This article deals with the preparation of the experimental chamber on which, among other things, stagnation and static temperature will be measured. The results obtained from the measurements will be compared with the results of mathematical-physics analyzes of the Ansys Fluent system. Due to the expected temperature drop during pumping, the analyzes of the given pumping process were made for the selection of suitable probes for the cryogenic mode were also performed.
Numerical Simulation of an Air Cooling System for Lithium-Ion Batteries
Authors: Madani Seyed Saeed
Published: December 2020

The technology of lithium-ion batteries could be beneficial for electric vehicle applications. During the acceleration of electric vehicles, a big rate of discharge is needed. The higher charge and discharge rates produce a bigger temperature in lithium-ion batteries. Lithium-ion batteries are big energy materials and so there are safety concerns related to these batteries. Working at big temperatures causes several issues for lithium-ion batteries. In this investigation, the computational fluid dynamics procedure by Ansys was used for simulation of an air cooling system that can be used for thermal management of lithium-ion batteries. Different configurations were selected for the simulation. It was concluded that it is not feasible to provide a homogeneous temperature distribution in lithium-ion battery surface and battery pack by employing air cooling for thermal management of lithium-ion batteries.
High Power Wireless Power Transfer with Inductive Coupling
Authors: Tomanek Radek , Martiš Jan , Vorel Pavel
Published: December 2020

This paper describes the design of a high power wireless power transfer with a coupled series resonant circuit. Coils distance is 600 mm and a nominal power is 20 kW. The transfer is provided by the inductive coupling of the resonant circuit with 800 mm diameter coils. The resonant circuit is powered by an inverter with IGBT modules working on frequency 130 kHz. The functionality of the realized device is verified by measurements, the evaluation of which is at the end of the article.
The Thermodynamic Model for Vacuum Technology
Authors: Horak Vladimir , Phan Bui Thanh , Do Duc Linh
Published: December 2020

The paper is focused on developing a mathematical model capable to describe thermodynamic processes connected with the vacuum technique. The model is based on the laws of energy and mass conservation, the air state behavior, and the principles of airflow, including the critical flow. The problem has been solved numerically by MATLAB. The results of the solution include the pressure evolution for a given pumping speed and the volume to be evacuated. Solutions are obtained for cases of airflow to the vacuum chamber through an inlet opening for three various diameters. The solutions are validated by comparing with experimental data. The presented model agrees with the experiment quite well. One very useful application is the determination of the relation between the diameter of the inlet opening and the pumping speed of the vacuum pump at the pressure steady state condition. This is an important knowledge for a simple and reliable quantitative pressure control in vacuum systems.
Testing of a Prototype Device Using Electrochemical Impedance Spectroscopy (EIS) Method
Authors: Zsigmond András , Libich Jiri
Published: December 2020

This paper deals with the electrochemical processes in lithium-ion batteries. To characterize the different electrochemical processes a method called electrochemical impedance spectroscopy (EIS) is used. The devices which perform EIS analysis are spread in all electrochemical laboratories but are expensive and their operation need certain level of knowledge and experience. This work is aiming to provide low-cost, user friendly device for EIS analysis The prototype of experimental device which utilize EIS method to characterize electrochemical parameters of cell is described. The prototype EIS device is tested and obtained results are compared with reference unit.
The Usage of the Power Load as a Physical Diagram for Electric Vehicle Charging Modelling
Authors: Sitar Vladislav , Rakova Lenka , Hruska Tomas , Vyslouzil Tomas
Published: December 2020

The development of electric vehicles (EVs) brings a lot of new problems from the point of view of the electrical grid. Electric vehicles (EV) charging causes an impact load on the distribution grid, which is often non-symmetrical, and can reach high levels in relevant parts of the grid. This leads to deterioration of the electrical energy parameters, mainly voltage level and its symmetry. The inverters operation in electric vehicle charging stations (EVCSs) generates harmonics, which also leads to deterioration of the voltage quality. In the case of simultaneous charging of a large number of EVs from a poorly designed distribution grid, significant losses inside conductors occur, and the service life of the distribution grid is shortened. In the paper, the authors deal with the modelling of EVCSs by using an alternative simulation tool when charging them as a power load, which consumes predefined active power with desired level and duration at supply voltage changes in the grid. Such defined load differs from a general load in its behaviour. The authors’ created load model is based on the real measured data. The behaviour of the created power load model is verified in the paper on a small distribution grid, where individual power consumers correspond to the standardized daily load diagrams of households and services. The goal of the paper is to verify the proposed power load model. The load model is used for solving active power losses in conductors of the electrical distribution lines, and mainly the levels of supplied voltage.
Can a Transport Model Predict Inverse Signatures in Lithium Metal Batteries Without Modifying Kinetics?
Authors: Uppaluri Maitri , Subramaniam Akshay , Mishra Lubhani , Viswanathan Vilayanur , Subramanian Venkat R.
Published: December 2020

In this study, a one-dimensional transport model is developed and analyzed to predict the inverse overpotential signature observed during lithium metal electrodeposition. This simple approach predicts inverse signatures stemming from the competing interplay between moving boundary rates and mass transfer limitations. The numerical scheme used for the present model simulations is presented in detail which has been further used to study the effect of design parameters on the prevalence and strength of inverse signatures. It was found that the proposed model and the analysis is more pertinent to thick lithium symmetric cells, commonly used for in-depth fundamental studies.
Incorporating the Number of PLN into the AJCC Stage Could Better Predict the Survival for Patients with NSCLC: A Large Population-Based Study
Authors: Shang Xiaoling , Li Zhenxiang , Lin Jiamao , Yu Haining , Zhao Chenglong , Wang Haiyong , Sun Jian
Published: December 2020

Purpose. This study aimed to investigate the application of the number of positive lymph nodes (PLNs) in tumor, node, metastasis (TNM) staging system of non-small cell lung cancer (NSCLC) patients. Patients and Methods. We screened a total of 15820 patients with resected NSCLC between 2004 and 2015 from SEER database. The X-tile model was used to determine the cutoff values of the number of PLNs. Overall survival (OS) curves were plotted using the Kaplan–Meier method, and the differences among the individual groups were defined using the log-rank test. Cox regression model was used to perform univariate and multivariate analyses and to assess the association between the number of PLNs and OS. Results. In this study, using the X-tile model, we screened three different cutoff values, including nN0, nN1–3, and nN4-. Survival curves demonstrated that our defined nN stage had a significant predictive value for OS (

P
<
0.001

). In the univariate and multivariate Cox analyses, the result showed that nN stage was a significant prognostic factor of OS for NSCLC patients (

P
<
0.001

). Subsequently, we classified the patients into five subgroups based on the combination of pN and nN stages, including pN0 + nN0, pN1 + nN1-3, pN2 + nN1-3, pN1 + nN4-, and pN2 + nN4-. Moreover, survival curves revealed significant differences among these five groups (

P
<
0.001

). Conclusion. A combination of pathological LNs (pN) and the number of LN (nN) involvement in NSCLC patients had a better prognostic value than the current TNM staging system based on only pN stage.
Perioperative Management of Metastatic Paraganglioma-Pheochromocytoma of the Humerus with the Aid of Regional Anesthesia
Authors: Muse Iyabo O. , Vivek Kumar , Bloomgarden Noah A , Singla Amit , Geller David S.
Published: December 2020

A 38-year-old female with a past history of pheochromocytoma and subsequent malignant paraganglioma presented with right arm pain after a fall. Imaging demonstrated a malunited humeral shaft associated with a large cortical destructive lesion and extraosseous extension. Here, we report the use of a multidisciplinary team approach including an endocrinologist, anesthesiologist, and orthopedic surgeon in the perioperative management of a patient with metastatic paraganglioma undergoing a surgical resection of the humerus, internal fixation, reconstruction, and placement of endoprosthesis. The challenges of perioperative anesthetic management and the use of regional anesthesia, especially peripheral nerve block for perioperative pain management, are highlighted.
The Expression and Prognostic Value of FGF2, FGFR3, and FGFBP1 in Esophageal Squamous Cell Carcinoma
Authors: Zhang Wenjing , Zhou Yaxing , Li Chao , Xu Shanshan , Li Mengyan , Liu Wenying , Ma Yuqing , Wang Hui
Published: December 2020

Background. Esophageal squamous cell carcinoma was treated by operation and chemoradiotherapy. However, the prognosis of most patients is poor after treatment, and most studies have shown that FGF2 and its receptor (FGFR) are involved in the development of various malignant tumors. FGF2 plays an important role in tumor progression and malignancy. In this study, the immunohistochemistry of FGF2, FGFR3, and FGFBP1 was used to further verify the expression of the three proteins in 172 patients with esophageal squamous cell carcinoma (ESCC) who had not received preoperative chemoradiotherapy and its effect on the prognosis of ESCC. Methods. (1)χ2test was used to analyze the relationship between proteins and clinicopathological parameters. Survival analysis was used to investigate the effect of three proteins on prognosis. (2) Paired samplet-test was used to analyze the mRNA expression of the three proteins in fresh ESCC tissues and adjacent normal tissues. Results. FGF2 was correlated with tumor size (p=0.026), gender (p=0.047), and lymph metastasis (p=0.007) in ESCC tissues. The high expression of FGFR3 was associated with tumor differentiation (p=0.043andp<0.05), lymph node metastasis (p=0.078andp<0.1), and race (p=0.033andp<0.05). The high expression of FGFBP1 was significantly associated with the degree of tumor differentiation (p=0.012), age (p=0.045), and lymph node metastasis (p=0.032) of ESCC patients. The expression of FGF2, FGFR3, and FGFBP1-mRNA in ESCC tissues was significantly higher than that in adjacent tissues (p<0.001,p<0.001, andp=0.001). Patients with high expression of FGF2, FGFBP1, and FGFR3 had poor prognosis. There was a weak positive correlation between FGF2 and FGFBP1, as well as FGFR. Conclusion. The FGF2-FGFR3 axis may promote the progression of esophageal squamous cell carcinoma. The FGF2-FGFR3 axis may be a new direction of targeted therapy for esophageal squamous cell carcinoma. FGF2 and FGFR3 may be used as prognostic markers of esophageal squamous cell carcinoma.