bluuebunny/crossref_metadata_2025 huggingface dataset:
SAVTA: A Hybrid Vehicular Threat Model: Overview and Case Study
Authors: Hamad Mohammad , Prevelakis Vassilis
Published: May 2020

In recent years, significant developments were introduced within the vehicular domain, evolving the vehicles to become a network of many embedded systems which depend on a set of sensors to interact with each other and with the surrounding environment. While these improvements have increased the safety and incontestability of the automotive system, they have opened the door for new potential security threats which need to be defined, assessed, and mitigated. The SAE J3061 standard has defined threat modeling as a critical step toward the secure development process for vehicle systems, but it did not determine which method could be used to achieve this process. Therefore, many threat modeling approaches were adopted. However, using one individual approach will not identify all the threats which could target the system, and may lead to insufficient mitigation mechanisms. Thus, having complete security requires the usage of a comprehensive threat model which identifies all the potential threats and vulnerabilities. In this work, we tried to revise the existing threat modeling efforts in the vehicular domain. Also, we proposed using a hybrid method called the Software, Asset, Vulnerability, Threat, and Attacker (SAVTA)-centric method to support security analysis for vehicular systems. SAVTA combines different existing threat modeling approaches to create a comprehensive and hybridized threat model. The model is used as an aid to construct general attack trees which illustrate attack vectors that threaten a particular vehicle asset and classify these attacks under different sub-trees.
Quantitative Evaluation of Dense Skeletons for Image Compression
Authors: Wang Jieying , Terpstra Maarten , Kosinka Jiří , Telea Alexandru
Published: May 2020

Skeletons are well-known descriptors used for analysis and processing of 2D binary images. Recently, dense skeletons have been proposed as an extension of classical skeletons as a dual encoding for 2D grayscale and color images. Yet, their encoding power, measured by the quality and size of the encoded image, and how these metrics depend on selected encoding parameters, has not been formally evaluated. In this paper, we fill this gap with two main contributions. First, we improve the encoding power of dense skeletons by effective layer selection heuristics, a refined skeleton pixel-chain encoding, and a postprocessing compression scheme. Secondly, we propose a benchmark to assess the encoding power of dense skeletons for a wide set of natural and synthetic color and grayscale images. We use this benchmark to derive optimal parameters for dense skeletons. Our method, called Compressing Dense Medial Descriptors (CDMD), achieves higher-compression ratios at similar quality to the well-known JPEG technique and, thereby, shows that skeletons can be an interesting option for lossy image encoding.
Ecology of the Western Queen Butterfly Danaus gilippus thersippus (Lepidoptera: Nymphalidae) in the Mojave and Sonoran Deserts
Authors: Saul-Gershenz Leslie , Grodsky Steven M. , Hernandez Rebecca R.
Published: May 2020

The purpose of this study was to assess the ecological knowledge surrounding the western queen butterfly, Danaus gilippus thersippus (H. Bates). Specifically, our objectives were to synthesize existing data and knowledge on the ecology of the queen and use results of this assessment to inform the direction of future research on this understudied species. We identified six core areas for assessment: distribution, the biodiversity of plant resources, western queen and their host plant phenology, chemical ecology, and four key life history traits. We mapped the distribution of D. g. thersippus from museum specimen records, citizen science (e.g., iNaturalist) and image sharing app-based observations, along with other observational data enumerating all current known plant resources and long-range movements. We assembled 14 larval food plants, six pyrrolizidine alkaloids plants and six nectar plants distributed in the western Mojave and Sonoran Desert regions of the United States and Baja California. We report on its phenology and its long-range movement. Butterfly species have declined across the western US, and western monarch populations have declined by 97%. Danaus g. thersippus has received little research attention compared with its famous congener D. plexippus L. Danaus g. thersippus’ desert distribution may be at its temperature limits for the species distribution and for its rare host plant Asclepias nyctaginifolia.
IEC61800-9 System Standards as a Tool to Boost the Efficiency of Electric Motor Driven Systems Worldwide
Authors: Fong João , Ferreira Fernando J. T. E. , Silva André M. , de Almeida Aníbal T.
Published: May 2020

Recognition of the energy savings potential in motor driven systems has led to the development of energy efficiency testing and classification standards for motors and end-use equipment (e.g., pumps and fans) and the implementation of minimum energy performance regulations targeting them worldwide. However, these standards and regulations have been limited to components, disregarding the interaction between them. The energy savings achievable by addressing and improving the entire system are potentially much higher in relation to those achievable when considering individual components. Recently, an effort to develop standards in this regard was carried out by standardization bodies (IEC and ISO) leading to the publication of the IEC61800-9 Power Drive System standard series. The paper, in its first part, describes recent evolutions in electric motor energy-efficiency standards and in the implementation of related regulations worldwide. In the second part of the paper, using the latest energy efficiency test and classification standards, a comparative analysis of different energy-efficient motor technologies is presented. Using results from laboratory tests combined with data provided by manufacturers, different power drive systems are compared considering different operating points in two typical pumping systems. Estimated economic savings from a total cost of ownership perspective are presented.
A Continuous Renal Replacement Therapy Protocol for Patients with Acute Kidney Injury in Intensive Care Unit with COVID-19
Authors: Nalesso Federico , Garzotto Francesco , Cattarin Leda , Gobbi Laura , Qassim Laila , Sgarabotto Luca , Tiberio Ivo , Calò Lorenzo A.
Published: May 2020

COVID-19 often leads to acute respiratory distress syndrome complicated by acute kidney injury (AKI). The indications for renal replacement therapy for these patients are those commonly accepted to treat AKI. We describe a continuous veno-venous haemodialysis (CVVHD) protocol for AKI, which aims to provide the best treatment according to the particular patient’s and medical personnels’ needs in biohazard settings with limited human and technological resources. We designed a CVVHD protocol with a high cut-off (HCO) filter in regional citrate anticoagulation (RCA). The HCO filter in diffusion determines the enhanced cytokines clearance with less filter clotting due to a lower filtration fraction. In our hospital, at the beginning of the pandemic outbreak, we treated seven COVID-19 patients with AKI stage 2 and 3 and recorded the circuit lifespan and the number of interventions on monitors. CVVHD in RCA appears to be safe, effective and easy to be performed in a biohazard scenario using lower blood flows and less bag changes with fluid savings, a biohazard reduction and sparing of resources. Although the data come from a very small cohort, our protocol seems related to a low mortality.
Hypothalamic Neuropeptide Brain Protection: Focus on Oxytocin
Authors: Panaro Maria Antonietta , Benameur Tarek , Porro Chiara
Published: May 2020

Oxytocin (OXT) is hypothalamic neuropeptide synthetized in the brain by magnocellular and parvo cellular neurons of the paraventricular (PVN), supraoptic (SON) and accessory nuclei (AN) of the hypothalamus. OXT acts in the central and peripheral nervous systems via G-protein-coupled receptors. The classical physiological functions of OXT are uterine contractions, the milk ejection reflex during lactation, penile erection and sexual arousal, but recent studies have demonstrated that OXT may have anti-inflammatory and anti-oxidant properties and regulate immune and anti-inflammatory responses. In the pathogenesis of various neurodegenerative diseases, microglia are present in an active form and release high levels of pro-inflammatory cytokines and chemokines that are implicated in the process of neural injury. A promising treatment for neurodegenerative diseases involves new therapeutic approaches targeting activated microglia. Recent studies have reported that OXT exerts neuroprotective effects through the inhibition of production of pro-inflammatory mediators, and in the development of correct neural circuitry. The focus of this review is to attribute a new important role of OXT in neuroprotection through the microglia–OXT interaction of immature and adult brains. In addition, we analyzed the strategies that could enhance the delivery of OXT in the brain and amplify its positive effects.
Relationship between Performance on the Mini-Mental State Examination Sub-Items and Activities of Daily Living in Patients with Alzheimer’s Disease
Authors: Han Gwanghee , Maruta Michio , Ikeda Yuriko , Ishikawa Tomohisa , Tanaka Hibiki , Koyama Asuka , Fukuhara Ryuji , Boku Shuken , Takebayashi Minoru , Tabira Takayuki
Published: May 2020

Mini-mental state examination (MMSE) subitems provide useful information about the cognitive status of patients with Alzheimer’s disease (AD). If the relationship between MMSE subitems and activities of daily living (ADL) can be shown, the performance of sub-items can predict ADL status and may provide useful information for early ADL intervention. Therefore, the purpose of this study was to investigate the relationship between MMSE subitem scores and ADL. The study sample consisted of 718 patients with AD. Logistic regression analysis using the Physical Self-maintenance Scale (PSMS) and Lawton’s Instrumental ADL (L-IADL) was performed with each of the subitems as the dependent variables and the MMSE subitem as the independent variable. As a result, the subitems of MMSE, which are strongly related to each item in PSMS differed (e.g., toilet: registration odds ratio 3.00, grooming: naming 3.66). In the case of L-IADL, most items were strongly associated with “writing” (e.g., shopping: odds ratio 4.29, laundry 3.83). In clinical practice, we often focus only on the total MMSE score in patients with AD. However, the relationship between each MMSE subitem and ADL suggested in this study may be useful information that can be linked to ADL care from the performance of the MMSE subitem.
Comparing Eight Prognostic Scores in Predicting Mortality of Patients with Acute-On-Chronic Liver Failure Who Were Admitted to an ICU: A Single-Center Experience
Authors: Chen Bo-Huan , Tseng Hsiao-Jung , Chen Wei-Ting , Chen Pin-Cheng , Ho Yu-Pin , Huang Chien-Hao , Lin Chun-Yen
Published: May 2020

Limited data is available on long-term outcome predictions for patients with acute-on-chronic liver failure (ACLF) in an intensive care unit (ICU) setting. Assessing the reliability and accuracy of several mortality prediction models for these patients is helpful. Two hundred forty-nine consecutive patients with ACLF and admittance to the liver ICU in a single center in northern Taiwan between December 2012 and March 2015 were enrolled in the study and were tracked until February 2017. Ninety-one patients had chronic hepatitis B-related cirrhosis. Clinical features and laboratory data were collected at or within 24 h of the first ICU admission course. Eight commonly used clinical scores in chronic liver disease were calculated. The primary endpoint was overall survival. Acute physiology and chronic health evaluation (APACHE) III and chronic liver failure consortium (CLIF-C) ACLF scores were significantly superior to other models in predicting overall mortality as determined by time-dependent receiver operating characteristic (ROC) curve analysis (area under the ROC curve (AUROC): 0.817). Subgroup analysis of patients with chronic hepatitis B-related cirrhosis displayed similar results. CLIF-C organ function (OF), CLIF-C ACLF, and APACHE III scores were statistically superior to the mortality probability model III at zero hours (MPM0-III) and the simplified acute physiology (SAP) III scores in predicting 28-day mortality. In conclusion, for 28-day and overall mortality prediction of patients with ACLF admitted to the ICU, APACHE III, CLIF-OF, and CLIF-C ACLF scores might outperform other models. Further prospective study is warranted.
Outcomes of Chronic Phase Chronic Myeloid Leukemia after Treatment with Multiple Tyrosine Kinase Inhibitors
Authors: Kong Jee Hyun , Winton Elliott F. , Heffner Leonard T. , Gaddh Manila , Hill Brittany , Neely Jessica , Hatcher Angela , Joseph Meena , Arellano Martha , El-Rassi Fuad , Kim Audrey , Khoury Jean Hanna , Kota Vamsi K.
Published: May 2020

We sought to evaluate the outcomes of chronic phase (CP) chronic myeloid leukemia (CML) in an era where five tyrosine kinase inhibitors (TKIs) are commercially available for the treatment of CML. Records of patients diagnosed with CP CML, treated with TKIs and referred to our center were reviewed. Between January 2005 and April 2016, 206 patients were followed for a median of 48.8 (1.4–190.1) months. A total of 76 (37%) patients received one TKI, 73 (35%) received two TKIs and 57 (28%) were exposed to >3 TKIs (3 TKIs, n = 33; 4 TKIs, n = 17; 5 TKIs, n = 7). Nineteen (9.2%) patients progressed to advanced phases of CML (accelerated phase, n = 6; myeloid blastic phase, n = 4; lymphoid blastic phase, n = 9). One third (n = 69) achieved complete molecular response (CMR) at first-line treatment. An additional 55 patients achieved CMR after second-line treatment. Twenty-five patients (12.1%) attempted TKI discontinuation and 14 (6.8%) stopped TKIs for a median of 6.3 months (range 1–53.4). The 10-year progression-free survival and overall survival (OS) rates were 81% and 87%, respectively. OS after 10-years, based on TKI exposure, was 100% (1 TKI), 82% (2 TKIs), 87% (3 TKIs), 75% (4 TKIs) and 55% (5 TKIs). The best OS was observed in patients tolerating and responding to first line TKI, but multiple TKIs led patients to gain treatment-free remission.
Increased Cell-Free DNA Plasma Concentration Following Liver Transplantation Is Linked to Portal Hepatitis and Inferior Survival
Authors: Krenzien Felix , Katou Shadi , Papa Alba , Sinn Bruno , Benzing Christian , Feldbrügge Linda , Kamali Can , Brunnbauer Philipp , Splith Katrin , Lorenz Ralf Roland , Ritschl Paul , Wiering Leke , Öllinger Robert , Schöning Wenzel , Pratschke Johann , Schmelzle Moritz
Published: May 2020

Donor organ quality is crucial for transplant survival and long-term survival of patients after liver transplantation. Besides bacterial and viral infections, endogenous damage-associated molecular patterns (DAMPs) can stimulate immune responses. Cell-free DNA (cfDNA) is one such DAMP that exhibits highly proinflammatory effects via DNA sensors. Herein, we measured cfDNA after liver transplantation and found elevated levels when organs from resuscitated donors were transplanted. High levels of cfDNA were associated with high C-reactive protein, leukocytosis as well as granulocytosis in the recipient. In addition to increased systemic immune responses, portal hepatitis was observed, which was associated with increased interface activity and a higher numbers of infiltrating neutrophils and eosinophils in the graft. In fact, the cfDNA was an independent significant factor in multivariate analysis and increased concentration of cfDNA was associated with inferior 1-year survival. Moreover, cfDNA levels were found to be decreased significantly during the postoperative course when patients underwent continuous veno-venous haemofiltration. In conclusion, patients receiving livers from resuscitated donors were characterised by high postoperative cfDNA levels. Those patients showed pronounced portal hepatitis and systemic inflammatory responses in the short term leading to a high mortality. Further studies are needed to evaluate the clinical relevance of cfDNA clearance by haemoadsorption and haemofiltration in vitro and in vivo.
Long-Term Performance of Trestle Bridges: Case Study of an Indonesian Marine Port Structure
Authors: Oktavianus Yusak , Sofi Massoud , Lumantarna Elisa , Kusuma Gideon , Duffield Colin
Published: May 2020

A precast reinforced concrete (RC) T-beam located in seaport Terminal Peti Kemas (TPS) Surabaya built in 1984 is used as a case study to test the accuracy of non-destructive test techniques against more traditional bridge evaluation tools. This bridge is mainly used to connect the berth in Lamong gulf and the port in Java Island for the logistic purposes. The bridge was retrofitted 26 years into its life by adding two strips of carbon fiber reinforced polymer (CFRP) due to excessive cracks observed in the beams. Non-destructive field measurements were compared against a detailed finite element analysis of the structure to predict the performance of the girder in terms of deflection and moment capacity before and after the retrofitting work. The analysis was also used to predict the long-term deflections of the structure due to creep, crack distribution, and the ultimate moment capacity of the individual girder. Moreover, the finite element analysis was used to predict the deflection behavior of the overall bridge due to vehicle loading. Good agreement was obtained between the field measurement and the analytical study. A new service life of the structure considering the corrosion and new vehicle demand is carried out based on field measurement using non-destructive testing. Not only are the specific results beneficial for the Indonesian port authority as the stakeholder to manage this structure, but the approach detailed also paves the way for more efficient evaluation of bridges more generally over their service life.
Monthly Art Market Returns
Authors: Bocart Fabian , Ghysels Eric , Hafner Christian
Published: May 2020

We provide an innovative methodological contribution to the measurement of returns on infrequently traded assets using a novel approach to repeat-sales regression estimation. The model for price indices we propose allows for correlation with other markets, typically with higher liquidity and high frequency trading. Using the new econometric approach, we propose a monthly art market index, as well as sub-indices for impressionist, modern, post-war, and contemporary paintings based on repeated sales at a monthly frequency. The correlations enable us to update the art index via observed transactions in other markets that have a link with the art market.
Risk and Financial Management of COVID-19 in Business, Economics and Finance
Authors: Chang Chia-Lin , McAleer Michael , Wong Wing-Keung
Published: May 2020

The SARS-CoV-2 coronavirus that causes the COVID-19 disease led to the most significant change in the world order over the past century, destabilizing the global economy and financial stock markets, the world’s economy, social development, business, risk, financial management and financial markets, among others. COVID-19 has generated great uncertainty, and dramatically affected tourism, travel, hospitality, supply chains, consumption, production, operations, valuations, security, financial stress and the prices of all products, including fossil fuel and renewable energy sources. This Editorial introduces a Special Issue of the Journal of Risk and Financial Management (JRFM) on the “Risk and Financial Management of COVID-19 in Business, Economics and Finance”. This Special Issue will attract practical, state-of-the-art applications of mathematics, probability and statistical techniques on the topic, including empirical applications. This paper investigates important issues that have been discussed in tourism, global health security and risk management in business as well as the social and medical sciences.
A Hypothesis Test Method for Detecting Multifractal Scaling, Applied to Bitcoin Prices
Authors: Jiang Chuxuan , Dev Priya , Maller Ross A.
Published: May 2020

Multifractal processes reproduce some of the stylised features observed in financial time series, namely heavy tails found in asset returns distributions, and long-memory found in volatility. Multifractal scaling cannot be assumed, it should be established; however, this is not a straightforward task, particularly in the presence of heavy tails. We develop an empirical hypothesis test to identify whether a time series is likely to exhibit multifractal scaling in the presence of heavy tails. The test is constructed by comparing estimated scaling functions of financial time series to simulated scaling functions of both an iid Student t-distributed process and a Brownian Motion in Multifractal Time (BMMT), a multifractal processes constructed in Mandelbrot et al. (1997). Concavity measures of the respective scaling functions are estimated, and it is observed that the concavity measures form different distributions which allow us to construct a hypothesis test. We apply this method to test for multifractal scaling across several financial time series including Bitcoin. We observe that multifractal scaling cannot be ruled out for Bitcoin or the Nasdaq Composite Index, both technology driven assets.
Recent Advances in the Photoautotrophic Metabolism of Cyanobacteria: Biotechnological Implications
Authors: Veaudor Théo , Blanc-Garin Victoire , Chenebault Célia , Diaz-Santos Encarnación , Sassi Jean-François , Cassier-Chauvat Corinne , Chauvat Franck
Published: May 2020

Cyanobacteria constitute the only phylum of oxygen-evolving photosynthetic prokaryotes that shaped the oxygenic atmosphere of our planet. Over time, cyanobacteria have evolved as a widely diverse group of organisms that have colonized most aquatic and soil ecosystems of our planet and constitute a large proportion of the biomass that sustains the biosphere. Cyanobacteria synthesize a vast array of biologically active metabolites that are of great interest for human health and industry, and several model cyanobacteria can be genetically manipulated. Hence, cyanobacteria are regarded as promising microbial factories for the production of chemicals from highly abundant natural resources, e.g., solar energy, CO2, minerals, and waters, eventually coupled to wastewater treatment to save costs. In this review, we summarize new important discoveries on the plasticity of the photoautotrophic metabolism of cyanobacteria, emphasizing the coordinated partitioning of carbon and nitrogen towards growth or compound storage, and the importance of these processes for biotechnological perspectives. We also emphasize the importance of redox regulation (including glutathionylation) on these processes, a subject which has often been overlooked.
Ubiquitous Electron Transport in Non-Electron Transfer Proteins
Authors: Lindsay Stuart
Published: May 2020

Many proteins that have no known role in electron transfer processes are excellent electronic conductors. This surprising characteristic is not generally evident in bulk aggregates or crystals, or in isolated, solvated peptides, because the outer hydrophilic shell of the protein presents a barrier to charge injection. Ligands that penetrate this barrier make excellent electrical contacts, yielding conductivities on the order of a S/m. The Fermi Energy of metal electrodes is aligned with the energy of internal electronic states of the protein, as evidenced by resonant transmission peaks at about 0.3V on the Normal Hydrogen Electrode scale. This energy is about 0.7 V less than the oxidation potential of aromatic amino acids, indicating a large reduction in electrostatic reorganization energy losses in the interior of the proteins. Consistent with a possible biological role for this conductance, there is a strong dependence on protein conformation. Thus, direct measurement of conductance is a powerful new way to read out protein conformation in real time, opening the way to new types of single molecule sensors and sequencing devices.
Effect of Hexagonal Boron nitride Nanopowder Reinforcement and Mixing Methods on Physical and Mechanical Properties of Self-Cured PMMA for Dental Applications
Authors: Alqahtani Mana
Published: May 2020

We report for the first time on the effect of biocompatible hexagonal boron nitride (h-BN) nanopowder reinforcement with different concentrations on the structural and mechanical properties of fabricated self-cured polymethyl methacrylate (PMMA) based dental materials (GC UNIFAST III). A comparison among the structural and mechanical properties between hand and ultrasonic mixing is also presented. Fabricated specimens were studied by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectrometry (FTIR), micro indentation, and flexural strength techniques. The ultrasonic mixing method provides better sample textures of the composite as compared to hand mixing. It is found that XRD and IR intensity of the peaks increases with the increase of h-BN concentration due to nanocomposite formation. The additions of h-BN nanoparticles to the acrylic resin enhanced the hardness and the flexibility values of the composites. Independently of the mixing method used, adding h-BN nanopowder relatively increases the Vickers Hardness numbers (VH) and Flexural Strength (FS) of the unmodified materials. However, using ultrasonic mixing method combined with h-BN nanopowder increases VH numbers to 300% and FS values to 550% with respect to the unmodified sample made by hand mixing. The results obtained are very encouraging and will support future research in vivo, to confirm whether PMMA loaded with h-BN nanoparticles is an improvement compared to current dental restorative materials.
An SPH Approach for Non-Spherical Particles Immersed in Newtonian Fluids
Authors: Kijanski Nadine , Krach David , Steeb Holger
Published: May 2020

Solid particles immersed in a fluid can be found in many engineering, environmental or medical fields. Applications are suspensions, sedimentation processes or procedural processes in the production of medication, food or construction materials. While homogenized behavior of these applications is well understood, contributions in the field of pore-scale fully resolved numerical simulations with non-spherical particles are rare. Using Smoothed Particle Hydrodynamics (SPH) as a simulation framework, we therefore present a modeling approach for Direct Numerical Simulations (DNS) of single-phase fluid containing non-spherically formed solid aggregates. Notable and discussed model specifications are the surface-coupled fluid–solid interaction forces as well as the contact forces between solid aggregates. The focus of this contribution is the numerical modeling approach and its implementation in SPH. Since SPH presents a fully resolved approach, the construction of arbitrary shaped particles is conveniently realizable. After validating our model for single non-spherical particles, we therefore investigate the motion of solid bodies in a Newtonian fluid and their interaction with the surrounding fluid and with other solid bodies by analyzing velocity fields of shear flow with respect to hydromechanical and contact forces. Results show a dependency of the motion and interaction of solid particles on their form and orientation. While spherical particles move to the centerline region, ellipsoidal particles move and rotate due to vortex formation in the fluid flow in between.
Bi3+ and Eu3+ Activated Luminescent Behaviors in Non-Stoichiometric LaO0.65F1.7 Structure
Authors: Yang Sungjun , Park Sangmoon
Published: May 2020

Optical materials composed of La1-p-qBipEuqO0.65F1.7 (p = 0.001–0.05, q = 0–0.1) were prepared via a solid-state reaction using La(Bi,Eu)2O3 and NH4F precursors at 1050 °C for two hours. X-ray diffraction patterns of the phosphors were obtained permitting the calculation of unit-cell parameters. The two La3+ cation sites were clearly distinguished by exploiting the photoluminescence excitation and emission spectra through Bi3+ and Eu3+ transitions in the non-stoichiometric host lattice. Energy transfer from Bi3+ to Eu3+ upon excitation with 286 nm radiation and its mechanism in the Bi3+- and Eu3+-doped host structures is discussed. The desired Commission Internationale de l’Eclairage values, including emissions in blue-green, white, and red wavelength regions, were obtained from the Bi3+- and Eu3+-doped LaO0.65F1.7 phosphors.
Transparent Ultrathin Metal Electrode with Microcavity Configuration for Highly Efficient TCO-Free Perovskite Solar Cells
Authors: He Fengqin , You Hailong , Li Xueyi , Chen Dazheng , Pang Shangzheng , Zhu Weidong , Xi He , Zhang Jincheng , Zhang Chunfu
Published: May 2020

Optical microcavity configuration is one optical strategy to enhance light trapping in devices using planar electrodes. In this work, the potential application of optical microcavity configuration with ultrathin metal electrodes in highly efficient perovskite solar cells (PSCs) was investigated. By comparing with the device with conventional indium-tin-oxide (ITO) electrodes, it is shown that by carefully designing the Ag/dielectric planar electrode, a device with an optical microcavity structure can achieve comparable—or even higher—power conversion efficiency than a conventional device. Moreover, there is a relative high tolerance for the Ag film thickness in the optical microcavity structure. When the thickness of the Ag film is increased from 8 to 12 nm, the device still can attain the performance level of a conventional device. This gives a process tolerance to fabricate devices with an optical microcavity structure and reduces process difficulty. This work indicates the great application potential of optical microcavities with ultrathin metal electrodes in PSCs; more research attention should be paid in this field.
Anisotropic Compressive Behavior of Metallic Foams under Extreme Temperature Conditions
Authors: Khezrzadeh Omid , Mirzaee Omid , Emadoddin Esmaeil , Linul Emanoil
Published: May 2020

Metallic foams find their applicability in complex systems that operate under both real-life conditions (Earth living conditions) and extreme temperature conditions (low or high temperatures). In this paper, the main mechanical properties of closed-cell aluminum alloy (A356) foams under quasi-static compression loading conditions were determined. In order to investigate the compressive behavior, three orthogonal directions (X, Y, and Z) and three testing temperatures (−196, 25 and 250 °C) were considered. It has been observed that the temperature significantly influences the strength properties and energy absorption performances of the aluminum metallic foams AMFs. Moreover, it was found that microstructural characteristics, such as intrinsic defects (intracellular cavities, micro-pores and thin cell-walls) and structural anisotropy (shape, size and orientation of cells), play a decisive role in the mechanical behavior of AMFs. Moreover, the paper compares the relative percentage change (relative percentage increase and decrease) of the main normalized compressive properties (yield stress, plateau stress, densification stress and the energy absorption) of AMF samples, according to testing temperature and loading direction.
Output of MEMS Piezoelectric Energy Harvester of Double-Clamped Beams with Different Width Shapes
Authors: Jin Lei , Gao Shiqiao , Zhang Xiyang , Wu Qinghe
Published: May 2020

For a microelectromechanical system (MEMS) piezoelectric energy harvester consisting of double-clamped beams, the effects of both beam shape and electrode arrangement on the voltage outputs are analyzed. For two kinds of harvester structures including millimeter-scale and micro-scale, and different shapes including rectangular, segmentally trapezoidal and concave parabolic are taken into account. Corresponding electric outputs are calculated and tested. Their results are in good agreement with each other. The experimental results validate the theoretical analysis.
Nonlinear Regression Operating on Microstructures Described from Topological Data Analysis for the Real-Time Prediction of Effective Properties
Authors: Yun Minyoung , Argerich Clara , Cueto Elias , Duval Jean Louis , Chinesta Francisco
Published: May 2020

Real-time decision making needs evaluating quantities of interest (QoI) in almost real time. When these QoI are related to models based on physics, the use of Model Order Reduction techniques allows speeding-up calculations, enabling fast and accurate evaluations. To accommodate real-time constraints, a valuable route consists of computing parametric solutions—the so-called computational vademecums—that constructed off-line, can be inspected on-line. However, when dealing with shapes and topologies (complex or rich microstructures) their parametric description constitutes a major difficulty. In this paper, we propose using Topological Data Analysis for describing those rich topologies and morphologies in a concise way, and then using the associated topological descriptions for generating accurate supervised classification and nonlinear regression, enabling an almost real-time evaluation of QoI and the associated decision making.
Flexible Electrode by Hydrographic Printing for Surface Electromyography Monitoring
Authors: Zeng Xiong , Dong Ying , Wang Xiaohao
Published: May 2020

Surface electromyography (sEMG) monitoring has recently inspired new applications in the field of patient diagnose, rehabilitation therapy, man–machine–interface and prosthesis control. However, conventional wet electrodes for sEMG recording cannot fully satisfy the requirements of these applications because they are based on rigid metals and conductive gels that cause signal quality attenuation, motion artifact and skin allergy. In this study, a novel flexible dry electrode is presented for sEMG monitoring. The electrode is fabricated by screen-printing a silver–eutectic gallium–indium system over a transfer tattoo paper, which is then hydrographically printed on 3D surface or human skin. Peano curve in open-network pattern is adopted to enhance the mechanics of the electrode. Hydrographic printing enables the electrode to attach to skin intimately and conformably, meanwhile assures better mechanical and electrical properties and therefore improves the signal quality and long-term wearability of the electrode. By recording sEMG signal of biceps under three kinds of movement with comparison to conventional wet electrode, the feasibility of the presented flexible dry electrode for sEMG monitoring was proved.
Corrosion Resistance of Modified Hexagonal Boron Nitride (h-BN) Nanosheets Doped Acrylic Acid Coating on Hot-Dip Galvanized Steel
Authors: Fan Yongzhe , Yang Huazhen , Fan Haisheng , Liu Qi , Lv Chuang , Zhao Xue , Yang Mingxu , Wu Jianjun , Cao Xiaoming
Published: May 2020

The hexagonal boron nitride (h-BN) nanosheets modified by silane coupling agent (KH560) were doped into acrylic acid coating on the surface of galvanized steel to improve its corrosion resistance. H-BN nanosheets modified by KH560 were prepared and characterised by scanning electron microscopy, transmission electron microscopy, atomic force microscopy, X-ray diffraction, and Fourier-transform infrared spectroscopy. The corrosion resistance of the acrylic acid coatings was measured by electrochemical testing. The results show that the corrosion current density of the coating with modified h-BN nanosheets was reduced from 2.2 × 10−5 A/cm2 to 2.3 × 10−7 A/cm2 compared with the acrylic acid coating. The impedance of the composite coating with modified h-BN is 4435 Ω·cm2, higher than the BNNS coating (2500 Ω·cm2) and the acrylic acid coating (1500 Ω·cm2). This is due to the physical barrier and electrical insulation properties of the hexagonal boron nitride (h-BN) nanosheets.
Purification for Carbon Nanotubes Synthesized by Flame Fragments Deposition via Hydrogen Peroxide and Acetone
Authors: Hammadi Asmaa H. , Jasim Ahmed M. , Abdulrazzak Firas H. , Al-Sammarraie Abdulkareem M. A. , Cherifi Yacine , Boukherroub Rabah , Hussein Falah H.
Published: May 2020

Carbon nanotubes (CNTs) are synthesized by the flame fragment deposition (FFD) technique using Iraqi liquefied petroleum gas (LPG) as a source of carbon in a hand-made reactor at a low temperature (160 °C) without using a catalyst. Purification of the multi-walled carbon nanotubes (MWCNTs) is carried out using a two-step process consisting of sonication in 30 wt.% hydrogen peroxide (H2O2) solution at room temperature to remove amorphous impurities adhering to the walls of the CNTs and carbon nanoparticles (CNPs), followed by sonication in an acetone bath to remove the polyaromatic hydrocarbons (PAH) formed during the LPG gas burning. Comprehensive characterizations such as X-ray diffraction (XRD), atomic force microscopy (AFM), thermo-gravimetric analysis (TGA), and transmission electron microscopy (TEM) were conducted to verify the efficiency of the purification process. The results clearly demonstrated that this process is promising for the purification of the synthesized CNTs.
Experimental Laboratory Testing on Behavior of Dowels in Concrete Pavements
Authors: Zuzulova Andrea , Grosek Jiri , Janku Michal
Published: May 2020

This paper describes the testing of effectiveness and behavior of dowels placed in transversal joints of concrete pavements, while focusing on dimensions and quality of commonly used materials. The analysis uses experimental tests in laboratory conditions which were performed independently in the Czech Republic and Slovak Republic. The comparison of quality as well as potential use of alternative materials of dowels is made with the use of developed tests focusing on main requirements, such as longitudinal displacement in cement concrete, resistance of coating to damage, and reduced potential to concrete damage. Furthermore, the paper describes and compares loading results of the relative concrete deformations around dowels by strain gauges that were analyzed. Results of deformations on beams with an inserted dowel and the findings that were observed during the measurement are presented.
Special Issue: Conductive Polymers: Materials and Applications
Authors: Quijada César
Published: May 2020

Intrinsically conductive polymers (CPs) combine the inherent mechanical properties of organic polymers with charge transport, opto-electronic and redox properties that can be easily tuned up to those typical of semiconductors and metals. The control of the morphology at the nanoscale and the design of CP-based composite materials have expanded their multifunctional character even further. These virtues have been exploited to advantage in opto-electronic devices, energy-conversion and storage systems, sensors and actuators, and more recently in applications related to biomedical and separation science or adsorbents for pollutant removal. The special issue “Conductive Polymers: Materials and Applications” was compiled by gathering contributions that cover the latest advances in the field, with special emphasis upon emerging applications.
Strengthening of Bent LVL Beams with Near-Surface Mounted (NSM) FRP Reinforcement
Authors: Bakalarz Michał Marcin , Kossakowski Paweł Grzegorz , Tworzewski Paweł
Published: May 2020

The topic of the article is the analysis of the static work of unreinforced and reinforced with composite material timber beams under bending tests. The results of the experimental tests and a brief outline of the characteristics of the internal reinforcement of wood structures are presented. Experimental tests were performed on full-scale beams made of laminated veneer lumber (LVL) with nominal dimensions of 45 × 200 × 3400 mm. Two strips of carbon fiber-reinforced polymer (CFRP) reinforcement were glued into rectangular grooves in the component bottom with two-component epoxy resin (0.62% reinforcement percentage). The reinforcement mainly affected the enhancement of the maximum bending moment values evaluated at the points of application as having concentrated forces of 32% and 24% in comparison to the unreinforced elements. Increases of 11% and 7% in the global modulus of elasticity in the bending and stiffness coefficients were achieved, respectively. The failure of the reference beams was caused by exceeding the tensile strength of the LVL. The reinforced elements were characterized by a greater variation in failure mode, resulting from tension, compression or lateral torsional buckling. The strain profile reading showed a higher utilization of the compression characteristic of veneer in specimens reinforced with carbon laminates.
Mechanism of the Microstructural Evolution of 18Cr2Ni4WA Steel during Vacuum Low-Pressure Carburizing Heat Treatment and Its Effect on Case Hardness
Authors: Wang Bin , He Yanping , Liu Ye , Tian Yong , You Jinglin , Wang Zhaodong , Wang Guodong
Published: May 2020

In this study, vacuum low-pressure carburizing heat treatments were carried out on 18Cr2Ni4WA case-carburized alloy steel. The evolution and phase transformation mechanism of the microstructure of the carburized layer during low-temperature tempering and its effect on the surface hardness were studied. The results showed that the carburized layer of the 18Cr2Ni4WA steel was composed of a large quantity of martensite and retained austenite. The type of martensite matrix changed from acicular martensite to lath martensite from the surface to the core. The hardness of the carburized layer gradually decreased as the carbon content decreased. A thermodynamic model was used to show that the low-carbon retained austenite was easier to transform into martensite at lower temperatures, since the high-carbon retained austenite was more thermally stable than the low-carbon retained austenite. The mechanical stability—not the thermal stability—of the retained austenite in the carburized layer dominated after carburizing and quenching, and cryogenic treatment had a limited effect on promoting the martensite formation. During low-temperature tempering, the solid-solution carbon content of the martensite decreased, the compressive stress on the retained austenite was reduced and the mechanical stability of the retained austenite decreased. Therefore, during cooling after low-temperature tempering, the low-carbon retained austenite transformed into martensite, whereas the high-carbon retained austenite still remained in the microstructure. The changes in the martensite matrix hardness had a far greater effect than the transformation of the retained austenite to martensite on the case hardness of the carburized layer.
Effect of Exclusive Primer and Adhesive on Microtensile Bond Strength of Self-Adhesive Resin Cement to Dentin
Authors: Kim Bit-Na , Son Sung-Ae , Park Jeong-Kil
Published: May 2020

The aim of this study was to investigate the effect of G-CEM One Primer (GCOP) and self-etching adhesive on the microtensile bond strength (µTBS) between self-adhesive resin cement G-CEM One (GCO) and dentin. Teeth were sectioned to expose the flat dentin surface and randomly assigned into five groups (n = 15) according to the dentin surface treatment: 1) no surface treatment, 2) GCOP, 3) All-Bond Universal (ABU), 4) GCOP followed by ABU (GCOP/ABU), 5) ABU followed by GCOP (ABU/GCOP). The composite resin blocks were bonded to the dentin surface using GCO. The specimens were stored in distilled water at 37 °C for 24 h, then sectioned into sticks (1 mm × 10 mm). The μTBS values were statistically analyzed using 1-way analysis of variance (ANOVA) and Tukey’s honestly significant difference (HSD) test (α = 0.05) and failure mode was examined under a stereomicroscope. The bonding interface of each specimen was evaluated using confocal laser scanning microscopy. The GCOP group exhibited the highest µTBS value and there were no significant differences observed between GCOP, GCOP/ABU, ABU/GCOP groups (p > 0.05). The use of GCOP with GCO results in the improved µTBS between GCO and dentin. In conclusion, using only GCOP with GCO for bonding of indirect restoration is extremely simple and increasing bond strength.
Lie Group Analysis of Unsteady Flow of Kerosene/Cobalt Ferrofluid Past A Radiated Stretching Surface with Navier Slip and Convective Heating
Authors: Nabwey Hossam A. , Khan Waqar A. , Rashad Ahmed M.
Published: May 2020

In this work, we identified the characteristics of unsteady magnetohydrodynamic (MHD) flow of ferrofluid past a radiated stretching surface. Cobalt–kerosene ferrofluid is considered and the impacts of Navier slip and convective heating are additionally considered. The mathematical model which describes the problem was built from some partial differential equations and then converted to self-similar equations with the assistance of the Lie group method; after that, the mathematical model was solved numerically with the aid of Runge–Kutta–Fehlberg method. Graphical representations were used to exemplify the impact of influential parameters on dimensionless velocity and temperature profiles; the obtained results for the skin friction coefficient and Nusselt number were also examined graphically. It was demonstrated that the magnetic field, Navier slip, and solid volume fraction of ferroparticles tended to reduce the dimensionless velocity, while the radiation parameter and Biot number had no effects on the dimensionless velocity. Moreover, the magnetic field and solid volume fraction increase skin friction whereas Navier slip reduces the skin friction. Furthermore, the Navier slip and magnetic field reduce the Nusselt number, whereas solid volume fraction of ferroparticles, convective heating, and radiation parameters help in increasing the Nusselt number.
Structure and In Vitro Bioactivity against Cancer Cells of the Capsular Polysaccharide from the Marine Bacterium Psychrobacter marincola
Authors: Kokoulin Maxim S. , Kuzmich Alexandra S. , Romanenko Lyudmila A. , Chikalovets Irina V. , Chernikov Oleg V.
Published: May 2020

Psychrobacter marincola KMM 277T is a psychrophilic Gram-negative bacterium that has been isolated from the internal tissues of an ascidian Polysyncraton sp. Here, we report the structure of the capsular polysaccharide from P. marincola KMM 277T and its effect on the viability and colony formation of human acute promyelocytic leukemia HL-60 cells. The polymer was purified by several separation methods, including ultracentrifugation and chromatographic procedures, and the structure was elucidated by means of chemical analysis, 1-D, and 2-D NMR spectroscopy techniques. It was found that the polysaccharide consists of branched hexasaccharide repeating units containing two 2-N-acetyl-2-deoxy-d-galacturonic acids, and one of each of 2-N-acetyl-2-deoxy-d-glucose, d-glucose, d-ribose, and 7-N-acetylamino-3,5,7,9-tetradeoxy-5-N-[(R)-2-hydroxypropanoylamino]- l-glycero-l-manno-non-2-ulosonic acid. To our knowledge, this is the first finding a pseudaminic acid decorated with lactic acid residue in polysaccharides. The biological analysis showed that the capsular polysaccharide significantly reduced the viability and colony formation of HL-60 cells. Taken together, our data indicate that the capsular polysaccharide from P. marincola KMM 277T is a promising substance for the study of its antitumor properties and the mechanism of action in the future.