bluuebunny/crossref_metadata_2025 huggingface dataset:
Experimental Studies on Rock Thin-Section Image Classification by Deep Learning-Based Approaches
Authors: Li Diyuan , Zhao Junjie , Ma Jinyin
Published: July 2022

Experimental studies were carried out to analyze the impact of optimizers and learning rate on the performance of deep learning-based algorithms for rock thin-section image classification. A total of 2634 rock thin-section images including three rock types—metamorphic, sedimentary, and volcanic rocks—were acquired from an online open-source science data bank. Four CNNs using three different optimizer algorithms (Adam, SGD, RMSprop) under two learning-rate decay schedules (lambda and cosine decay modes) were trained and validated. Then, a systematic comparison was conducted based on the performance of the trained model. Precision, f1-scores, and confusion matrix were adopted as the evaluation indicators. Trials revealed that deep learning-based approaches for rock thin-section image classification were highly effective and stable. Meanwhile, the experimental results showed that the cosine learning-rate decay mode was the better option for learning-rate adjustment during the training process. In addition, the performance of the four neural networks was confirmed and ranked as VGG16, GoogLeNet, MobileNetV2, and ShuffleNetV2. In the last step, the influence of optimization algorithms was evaluated based on VGG16 and GoogLeNet, and the results demonstrated that the capabilities of the model using Adam and RMSprop optimizers were more robust than that of SGD. The experimental study in this paper provides important practical value for training a high-precision rock thin-section image classification model, which can also be transferred to other similar image classification tasks.
On the Property of Linear Autonomy for Symmetries of Fractional Differential Equations and Systems
Authors: Lukashchuk Stanislav Yu.
Published: July 2022

The problem of finding Lie point symmetries for a certain class of multi-dimensional nonlinear partial fractional differential equations and their systems is studied. It is assumed that considered equations involve fractional derivatives with respect to only one independent variable, and each equation contains a single fractional derivative. The most significant examples of such equations are time-fractional models of processes with memory of power-law type. Two different types of fractional derivatives, namely Riemann–Liouville and Caputo, are used in this study. It is proved that any Lie point symmetry group admitted by equations or systems belonging to considered class consists of only linearly-autonomous point symmetries. Representations for the coordinates of corresponding infinitesimal group generators, as well as simplified determining equations are given in explicit form. The obtained results significantly facilitate finding Lie point symmetries for multi-dimensional time-fractional differential equations and their systems. Three physical examples illustrate this point.
Non-Overlapping Domain Decomposition via BURA Preconditioning of the Schur Complement
Authors: Kosturski Nikola , Margenov Svetozar , Vutov Yavor
Published: July 2022

A new class of high-performance preconditioned iterative solution methods for large-scale finite element method (FEM) elliptic systems is proposed and analyzed. The non-overlapping domain decomposition (DD) naturally introduces coupling operator at the interface γ. In general, γ is a manifold of lower dimensions. At the operator level, a key property is that the energy norm associated with the Steklov-Poincaré operator is spectrally equivalent to the Sobolev norm of index 1/2. We define the new multiplicative non-overlapping DD preconditioner by approximating the Schur complement using the best uniform rational approximation (BURA) of Lγ1/2. Here, Lγ1/2 denotes the discrete Laplacian over the interface γ. The goal of the paper is to develop a unified framework for analysis of the new class of preconditioned iterative methods. As a final result, we prove that the BURA-based non-overlapping DD preconditioner has optimal computational complexity O(n), where n is the number of unknowns (degrees of freedom) of the FEM linear system. All theoretical estimates are robust, with respect to the geometry of the interface γ. Results of systematic numerical experiments are given at the end to illustrate the convergence properties of the new method, as well as the choice of the involved parameters.
Measuring the Mediating Roles of E-Trust and E-Satisfaction in the Relationship between E-Service Quality and E-Loyalty: A Structural Modeling Approach
Authors: Alnaim Abdullah F. , Sobaih Abu Elnasr E. , Elshaer Ibrahim A.
Published: July 2022

Despite a plethora of research studies on service quality, in general, and electronic (e) service quality, in particular, studies often focus on either understating the dimensions of e-service quality or its direct relationship with other variables such as customer e-satisfaction, e-trust, and e-loyalty. This study developed a comprehensive theoretical model to examine both direct and indirect influence of e-service quality on the e-loyalty of hotel customers in their usage of online travel agencies (OTAs). The research examines the mediating effect of e-trust and e-satisfaction in the relationship between e-service quality and e-loyalty. The research adopted a quantitative approach through a questionnaire survey for data collection from hotel customers who adopt OTAs for choosing their hotel services. Data collected from the questionnaires were analyzed using structural equation modeling (SEM). The results confirmed all direct relationships among e-service quality, e-trust, e-satisfaction, and e-loyalty. However, the results did not confirm a mediating role of either e-trust or e-satisfaction in the relationship between e-service quality and e-loyalty. Nonetheless, the results interestingly showed that both variables (trust and e-satisfaction) have a mediating role in the relationship between e-service quality and e-loyalty. The results of this research have numerous implications for senior tourism marketers, as well as marketing scholars.
Pension Funds, Insurance Companies and Stock Market Development: Evidence from Emerging Markets
Authors: Bayar Yilmaz , Gavriletea Marius Dan , Danuletiu Dan Constantin , Danuletiu Adina Elena , Sakar Emre
Published: July 2022

Stock markets foster economic growth through meeting the fund requirements of the firms by individual and institutional investors. Pension funds and insurance companies with their long-term investment horizon are critical institutional investors in capital markets. Therefore, this article explores the effect of pension funds and insurance companies on stock market development in 15 emerging market economies over the 2004–2019 period through panel cointegration and causality tests. The causality analysis revealed that stock market development had a significant impact on pension funds and the insurance sector in the short term. However, the cointegration analysis revealed that pension funds had a positive effect on stock market development in Brazil, Chile, Hungary, Mexico, Peru, and South Africa and the insurance sector had a positive impact on stock market development in Chile, Indonesia, Korea Republic, Philippines, and South Africa in the long term.
Quality of Sleep and Work Productivity among White-Collar Workers during the COVID-19 Pandemic
Authors: Žilinskas Emilijus , Puteikis Kristijonas , Mameniškienė Rūta
Published: July 2022

Background and Objectives: The COVID-19 pandemic has disrupted routine sleep and work patterns in the general population. We conducted an anonymous online survey among white-collar workers from various finance, IT and technology companies in Lithuania to define factors associated with worse sleep quality and diminished productivity during a COVID-19 lockdown. Materials and Methods: Employees of selected companies in Lithuania completed an anonymous questionnaire online that included the Pittsburgh Sleep Quality Index (PSQI), The Sleep Locus of Control (SLOC), the Generalized Anxiety Disorder Scale-7 (GAD-7), and the World Health Organization’s Health and Work Performance Questionnaire (WHO-HPQ). Respondents also provided information about their sleep hygiene, physical activity and alcohol use. Results: Data of 114 respondents (56, 49.1% male) were used for analysis. Among them, 49 (43.0%) suffered from poor sleep and 29 (25.4%) had clinically relevant levels of anxiety. However, there were only negligible levels of absenteeism in the sample (a median of zero hours of work lost over the past month). In a stepwise linear regression model (F(5,108) = 11.457, p < 0.001, R2adj = 0.316), high levels of anxiety, daily hours spent using the screen, use of electronic devices in the bedroom, smoking in the evening, and COVID-19-related changes in appetite were associated with worse sleep quality. Absenteeism was associated with physical activity of moderate intensity and decreased self-reported productivity during the pandemic (F(2,111) = 7.570, p = 0.001, R2adj = 0.104). However, there was no strong relationship between sleep-related variables (i.e., sleep hygiene, sleep locus of control, quality of sleep) or levels of anxiety and measures of work productivity. Conclusions: Our findings suggest that while bad sleep hygiene, anxiety, and changes in appetite are associated with worse sleep quality among white-collar workers during the pandemic, work productivity may remain high irrespective of disrupted sleep.
Lipid-Enriched Parenteral Nutrition and Bloodstream Infections in Hospitalized Patients: Is It a Real Concern?
Authors: Tota Antonio , Serra Amato , Raoul Pauline , Gasbarrini Antonio , Rinninella Emanuele , Mele Maria Cristina
Published: July 2022

Today, few clinicians are still convinced that lipids are sepsis risk factors in patients receiving parenteral nutrition. This dogma is principally based on old literature. This review deals with the most recent literature search that provided up-to-date data over the past ten years. Systematic research was performed on Pubmed, MEDLINE, and Web of Science. The recent evidence does not justify the exclusion of lipid emulsions in patients receiving parenteral nutrition for fear of bloodstream infection risk. Moreover, lipids represent a substantial proportion of the energy source providing essential fatty acids, potentially improving clinical outcomes in patients often malnourished. Understanding the actual risk factors of sepsis during parenteral nutrition is necessary to optimize patient nutritional status and care and avoid essential fatty acid deficiency. There is an urgent need to make updated nutrition training available at all levels of medical education.
Serum Concentrations of Thyroid-Stimulating Hormone, Triiodothyronine, and Thyroxine in Outpatients Infected with SARS-CoV2 in Khuzestan Province, Iran: A Disease Clinical Course Approach
Authors: Naghashpour Mahshid , Darvishi Ali , Adelipour Maryam , Bagheri Reza , Wong Alexei , Suzuki Katsuhiko , Golabi Sahar
Published: July 2022

Background and Objectives: The virus SARS-CoV2, which causes COVID-19, affects the endocrine system. This study investigated serum concentrations of the thyroid-stimulating hormone (TSH), triiodothyronine (T3), and thyroxine (T4) in 53 outpatients infected with SARS-CoV2 and 53 non-infected matched participants in Khuzestan Province, Iran. We also examined the possible association of clinical symptoms progression and disease severity with serum concentrations of TSH, T3, and T4. Materials and Methods: A checklist was applied to collect demographic and clinical data. Blood samples were taken for biochemical analysis of serum concentrations of TSH, T3, and T4. Clinical symptoms of the infected outpatients were monitored weekly for 28 days. Results: Our results indicated that, as the severity of the disease increased, the respiratory and pulse rates raised significantly. Additionally, disease severity was significantly different between genders. Specifically, 79.5% of the asymptomatic/mild, and 38.5% of moderate outpatients were men. We also found significantly lower serum T3 but higher T4 in infected outpatients, compared with controls. However, serum TSH did not significantly differ between the two groups. The generalized estimating equation (GEE) analysis revealed no relationship between clinical symptoms progression and disease severity with serum concentrations of TSH, T3, and T4 in our study population. Additionally, GEE analysis showed that the odds ratio of neurological symptoms among women was 2.5 times that of men, the odds ratio of neurological symptoms in illiterates was 10 times higher than that of those without a high-school diploma, and the chance of developing pulmonary symptoms in those without high-school diploma was about 21 times higher than illiterates. Conclusion: In conclusion, this study showed that infected outpatients had significantly lower serum T3 but higher T4 than non-infected participants. There was no relation between symptom progression and disease severity with serum concentrations of TSH, T3, and T4, but educational status and sex significantly affected the chance of neurological and pulmonary symptoms occurring over 28 days. Our results may be used to develop potential therapies to treat COVID-19 disease.
Separation of Chromium (VI), Copper and Zinc: Chemistry of Transport of Metal Ions across Supported Liquid Membrane
Authors: Goh Saik Su , Rafatullah Mohd , Ismail Norli , Alam Mahboob , Siddiqui Masoom Raza , Seow Eng-Keng
Published: July 2022

Prior to applying supported liquid membranes (SLM) with strip dispersion for separation of chromium (VI), copper and zinc, suitable chemical settings were determined through solvent extraction and stripping studies. More than 90% of copper and zinc could be simultaneously extracted with at least 3% (v/v) di-(2-ethylhexyl)phosphoric acid (D2EHPA) at a feed equilibrium pH in the range of 3.5–5.0. For stripping, theoretical model equations derived and experimental results revealed that suitable concentrations of lower acid strength reagents can strip metals that have weaker metal-extractant bond without significantly stripping metals that have a stronger metal-extractant bond. Therefore, in a setup comprising three compartments separated by two SLM, we propose to fill the three compartments in the following order: feed—strip dispersion containing low acid strength reagent—strong acid. An organic phase with 4% (v/v) D2EHPA was used. From stripping experiments, 0.2 mol/L pH 3 citrate buffer, which resulted in the highest copper recovery (88.8%) and solution purity (99.0%), was employed as the low acid strength reagent while the strong acid consisted of 1 mol/L sulfuric acid. In 26 h, 99.1% copper was recovered by citrate buffer with 99.8% purity and 95.1% zinc was recovered by sulfuric acid with 98.4% purity. Chromium (VI), copper and zinc could be separated effectively using this separation strategy.
Protein Kinase C Regulates Expression and Function of the Cav3.2 T-Type Ca2+ Channel during Maturation of Neonatal Rat Cardiomyocyte
Authors: Wang Yan , Morishima Masaki , Ono Katsushige
Published: July 2022

Two distinct isoforms of the T-type Ca2+ channel, Cav3.1 and Cav3.2, play a pivotal role in the generation of pacemaker potentials in nodal cells in the heart, although the isoform switches from Cav3.2 to Cav3.1 during the early neonatal period with an unknown mechanism. The present study was designed to investigate the molecular system of the parts that are responsible for the changes of T-type Ca2+ channel isoforms in neonatal cardiomyocytes using the whole-cell patch-clamp technique and mRNA quantification. The present study demonstrates that PKC activation accelerates the Ni2+-sensitive beating rate and upregulates the Ni2+-sensitive T-type Ca2+ channel current in neonatal cardiomyocytes as a long-term effect, whereas PKC inhibition delays the Ni2+-sensitive beating rate and downregulates the Ni2+-sensitive T-type Ca2+ channel current. Because the Ni2+-sensitive T-type Ca2+ channel current is largely composed of the Cav3.2-T-type Ca2+ channel, it is accordingly assumed that PKC activity plays a crucial role in the maintenance of the Cav3.2 channel. The expression of Cav3.2 mRNA was highly positively correlated with PKC activity. The expression of a transcription factor Nkx2.5 mRNA, possibly corresponding to the Cav3.2 channel gene, was decreased by an inhibition of PKCβII. These results suggest that PKC activation, presumably by PKCβII, is responsible for the upregulation of CaV3.2 T-type Ca2+ channel expression that interacts with a cardiac-specific transcription factor, Nkx2.5, in neonatal cardiomyocytes.
Influence of Wire Geometry on the Mechanical Behavior of the TiNi Design
Authors: Baigonakova Gulsharat , Marchenko Ekaterina , Kovaleva Marina , Vorozhtsov Alexander
Published: July 2022

The present article is aimed at studying the deformation behavior of TiNi wire and knitted metal TiNi mesh under uniaxial tension and revealing the role of wire geometry on their main mechanical characteristics and mechanisms of deformation behavior. The temperature dependence curve of the electrical resistance indicates that a two-stage martensitic transformation of B2→R→B19′ is occurring, and is responsible for the superelasticity effect. The TEM results showed that at room temperature, the TiNi wire has a nanocrystalline structure composed of B2 austenite grains. A change in the deformation mechanism was established under the uniaxial tension, where the TiNi wire exhibits the effect of superelasticity, while the knitted metal TiNi mesh made from this wire is characterized by hyperelastic behavior. Fracturing of the knitted metal TiNi mesh requires significant loads of up to 3500 MPa compared to the fracture load of the TiNi wire. With the uniaxial tension of the wire, which maximally repeats the geometry of the wire in knitted metal mesh, an increase in mechanical characteristics was observed.
Use of Molding Mixtures for the Production of Cast Porous Metals
Authors: Kroupová Ivana , Gawronová Martina , Lichý Petr , Merta Václav , Radkovský Filip
Published: July 2022

This paper aims to present the possibility of producing cast porous metals (or metallic foams) in a low-tech way by the use of conventional foundry technologies, i.e., the common procedures and materials. Due to the technological and economic complexity of the production processes of cast metallic foams, research into this material currently focuses on the development of less demanding technologies. The introduction of such production processes may help to exploit the full application potential of metallic foams. Within the framework of our proposed procedure, molding and core mixtures are used for the production of molds and filler material (space holder), also called precursors. It is the shape, size, and relative position of the individual precursors that determines the shape of the internal structure of the resulting metallic foam. The core mixture for the production of precursors is evaluated in terms of changes in properties with respect to storage time. Attention is focused on one of the most common bonding systems, furan no-bake. Casting tests are carried out for the possibility of making cast porous metals from aluminum alloy with different shapes of internal cavities depending on the different shapes of the filler material. The collapsibility of the cores after casting is evaluated for the test castings. The results show that even using commonly available materials and processes, cast metallic foams with complex internal structures can be produced.
Development of Ultrafine–Grained and Nanostructured Bioinert Alloys Based on Titanium, Zirconium and Niobium and Their Microstructure, Mechanical and Biological Properties
Authors: Sharkeev Yurii , Eroshenko Anna , Legostaeva Elena , Kovalevskaya Zhanna , Belyavskaya Olga , Khimich Margarita , Epple Matthias , Prymak Oleg , Sokolova Viktoriya , Zhu Qifang , Sun Zeming , Zhang Hongju
Published: July 2022

For this paper, studies of the microstructure as well as the mechanical and biological properties of bioinert titanium, zirconium, and niobium alloys in their nanostructured (NS) and ultrafine-grained (UFG) states have been completed. The NS and UFG states were formed by a combined two-step method of severe plastic deformation (SPD), first with multidirectional forging (MDF) or pressing into a symmetrical channel (PSC) at a given temperature regime, and then subsequent multi-pass groove rolling (MPGR) at room temperature, with pre-recrystallization annealing. Annealing increased the plasticity of the alloys in the NS and UFG states without changing the grain size. The UFG structure, with an average size of structural elements of no more than 0.3 μm, was formed as a result of applying two-step SPD and annealing. This structure presented significant improvement in the mechanical characteristics of the alloys, in comparison with the alloys in the coarse-grained (CG) or small-grained (SG) states. At the same time, although the formation of the UFG structure leads to a significant increase in the yield strength and tensile strength of the alloys, their elastic modulus did not change. In terms of biocompatibility, the cultivation of MG-63 osteosarcoma cells on the polished and sandblasted substrates demonstrated high cell viability after 10 days and good cell adhesion to the surface.
Structural Stability Analysis of Eye of the Yellow Sea, a Large-Span Arched Pedestrian Bridge
Authors: Chen Zhihua , Lin Hao , Wang Xiaodun , Liu Hongbo , Kawaguchi Ken’ichi , Matsui Minoru
Published: July 2022

To date, scholars’ research on the stability behavior of the arch structure mainly focuses on solid–web section arches, steel tubular truss arches and concrete-filled steel tubular arches, but the stability behavior of the novel spatial grid arch structure, which integrates the characteristics of grid structure and arch structure, is not yet clear. Based on the Eye of the Yellow Sea pedestrian bridge project in Rizhao, China, the stability behavior of this large-span spatial grid arch structure was studied, in this paper, by the project’s structure design team. The project is a glass covered steel arch pedestrian bridge with a span of 177 m, a height of 63.5 m, an elliptical section with a long axis of 18 m, and a short axis of 13.5 m. The elastic and the nonlinear elasto-plastic stability behavior considering different initial geometric imperfections, was analyzed by the ABAQUS finite element model. The buckling modes and the full-range load-displacement curve of the structure were analyzed, and the stress distribution, deformation mode and overall structural performance during the whole loading process were analyzed. The effects of initial imperfections, geometric nonlinearity and material nonlinearity on the ultimate load-carrying capacity of the structure were studied. The stability behavior of large-span spatial grid arch structure was studied in this paper, which provides an important reference for the design and analysis of such structures.
Severe COVID-19 Is Characterised by Perturbations in Plasma Amines Correlated with Immune Response Markers, and Linked to Inflammation and Oxidative Stress
Authors: Karu Naama , Kindt Alida , van Gammeren Adriaan J. , Ermens Anton A. M. , Harms Amy C. , Portengen Lutzen , Vermeulen Roel C. H. , Dik Willem A. , Langerak Anton W. , van der Velden Vincent H. J. , Hankemeier Thomas
Published: July 2022

The COVID-19 pandemic raised a need to characterise the biochemical response to SARS-CoV-2 infection and find biological markers to identify therapeutic targets. In support of these aims, we applied a range of LC-MS platforms to analyse over 100 plasma samples from patients with varying COVID-19 severity and with detailed clinical information on inflammatory responses (>30 immune markers). The first publication in a series reports the results of quantitative LC-MS/MS profiling of 56 amino acids and derivatives. A comparison between samples taken from ICU and ward patients revealed a notable increase in ten post-translationally modified amino acids that correlated with markers indicative of an excessive immune response: TNF-alpha, neutrophils, markers for macrophage, and leukocyte activation. Severe patients also had increased kynurenine, positively correlated with CRP and cytokines that induce its production. ICU and ward patients with high IL-6 showed decreased levels of 22 immune-supporting and anti-oxidative amino acids and derivatives (e.g., glutathione, GABA). These negatively correlated with CRP and IL-6 and positively correlated with markers indicative of adaptive immune activation. Including corresponding alterations in convalescing ward patients, the overall metabolic picture of severe COVID-19 reflected enhanced metabolic demands to maintain cell proliferation and redox balance, alongside increased inflammation and oxidative stress.
Numerical Study on the Cavitation Characteristics of Micro Automotive Electronic Pumps under Thermodynamic Effect
Authors: Wu Kaipeng , Ali Asad , Feng Changhong , Si Qiaorui , Chen Qian , Shen Chunhao
Published: July 2022

In order to study the influence of thermodynamic effects on the cavitation performance of hydromechanics, the Singhal cavitation model was modified considering the influence of the thermo-dynamic effects, and the modified cavitation model was written into CFX using the CEL language. Numerical simulation of the cavitation full flow field at different temperatures (25 °C, 50 °C and 70 °C) was carried out with the automotive electronic water pump as the research object. The results show that the variation trend of the external characteristic simulation and experimental values is the same at all flow rates, and the calculation accuracy meets the subsequent cavitation demand. With the increase in temperature, the low-pressure area inside the automotive electronic pump’s impeller decreases. NPSHr decreases and the cavitation resistance is enhanced. During the process of no cavitation to cavitation, the maximum pressure pulsation amplitude in the impeller channel gradually increases. The generation and collapse of cavitations cause the change of pressure pulsation in the internal flow field, causing pump vibration.
Miniaturized MIMO Antenna Array with High Isolation for 5G Metal-Frame Smartphone Application
Authors: Gao Yuehui , Wang Junlin , Wang Xin , Shao Rui
Published: July 2022

In this paper, a highly isolated multiple-input multiple-output (MIMO) antenna array is proposed for fifth-generation (5G) metal frame smartphones. The eight identical small-sized inverted F-shaped folded slots are etched on the metal frame as a MIMO antenna. The bandwidth of the antenna can be adjusted by changing one of the short branches of the antenna. The bandwidth of the antenna can reach the N79 band (4.4~5.0 GHz). By carefully arranging the positions of the eight antenna elements, ideal spatial diversity can be successfully achieved to mitigate the coupling between the antenna elements effectively. What is more, a small combination slot of C-shape (0.0078 × 0.047λ2) and vertical I-shape (0.12 × 0.004λ2) between each antenna element is introduced to improve the element isolation of the MIMO antenna system. The proposed MIMO array has been simulated, fabricated, and measured. The results show good impedance matching (return loss > 6 dB) and high isolation (>22 dB). Due to the decent element isolation, the envelope correlation coefficient (ECC) between each antenna element is below 0.049. It can provide a reliable anti-interference performance for the MIMO antenna system. In addition, the measured radiation efficiencies of the MIMO antenna system are higher than 50%. The interaction of the hand model with the MIMO antenna system is also investigated, including the specific absorption rate (SAR).
Vertical and Lateral Etch Survey of Ferroelectric AlN/Al1−xScxN in Aqueous KOH Solutions
Authors: Tang Zichen , Esteves Giovanni , Zheng Jeffrey , Olsson Roy H.
Published: July 2022

Due to their favorable electromechanical properties, such as high sound velocity, low dielectric permittivity and high electromechanical coupling, Aluminum Nitride (AlN) and Aluminum Scandium Nitride (Al1−xScxN) thin films have achieved widespread application in radio frequency (RF) acoustic devices. The resistance to etching at high scandium alloying, however, has inhibited the realization of devices able to exploit the highest electromechanical coupling coefficients. In this work, we investigated the vertical and lateral etch rates of sputtered AlN and Al1−xScxN with Sc concentration x ranging from 0 to 0.42 in aqueous potassium hydroxide (KOH). Etch rates and the sidewall angles were reported at different temperatures and KOH concentrations. We found that the trends of the etch rate were unanimous: while the vertical etch rate decreases with increasing Sc alloying, the lateral etch rate exhibits a V-shaped transition with a minimum etch rate at x = 0.125. By performing an etch on an 800 nm thick Al0.875Sc0.125N film with 10 wt% KOH at 65 °C for 20 min, a vertical sidewall was formed by exploiting the ratio of the 1011¯ planes and 11¯00 planes etch rates. This method does not require preliminary processing and is potentially beneficial for the fabrication of lamb wave resonators (LWRs) or other microelectromechanical systems (MEMS) structures, laser mirrors and Ultraviolet Light-Emitting Diodes (UV-LEDs). It was demonstrated that the sidewall angle tracks the trajectory that follows the 1¯212¯ of the hexagonal crystal structure when different c/a ratios were considered for elevated Sc alloying levels, which may be used as a convenient tool for structure/composition analysis.
Streptomyces: Still the Biggest Producer of New Natural Secondary Metabolites, a Current Perspective
Authors: Donald Lavinia , Pipite Atanas , Subramani Ramesh , Owen Jeremy , Keyzers Robert A. , Taufa Taitusi
Published: July 2022

There is a real consensus that new antibiotics are urgently needed and are the best chance for combating antibiotic resistance. The phylum Actinobacteria is one of the main producers of new antibiotics, with a recent paradigm shift whereby rare actinomycetes have been increasingly targeted as a source of new secondary metabolites for the discovery of new antibiotics. However, this review shows that the genus Streptomyces is still the largest current producer of new and innovative secondary metabolites. Between January 2015 and December 2020, a significantly high number of novel Streptomyces spp. have been isolated from different environments, including extreme environments, symbionts, terrestrial soils, sediments and also from marine environments, mainly from marine invertebrates and marine sediments. This review highlights 135 new species of Streptomyces during this 6-year period with 108 new species of Streptomyces from the terrestrial environment and 27 new species from marine sources. A brief summary of the different pre-treatment methods used for the successful isolation of some of the new species of Streptomyces is also discussed, as well as the biological activities of the isolated secondary metabolites. A total of 279 new secondary metabolites have been recorded from 121 species of Streptomyces which exhibit diverse biological activity. The greatest number of new secondary metabolites originated from the terrestrial-sourced Streptomyces spp.
Nisin and Nisin Probiotic Disrupt Oral Pathogenic Biofilms and Restore Their Microbiome Composition towards Healthy Control Levels in a Peri-Implantitis Setting
Authors: Radaic Allan , Brody Hanna , Contreras Fernando , Hajfathalian Maryam , Lucido Luke , Kamarajan Pachiyappan , Kapila Yvonne L.
Published: July 2022

Peri-implantitis is characterized by chronic inflammation of the peri-implant supporting tissues that progressively and irreversibly leads to bone loss and, consequently, implant loss. Similar to periodontal disease, oral dysbiosis is thought to be a driver of peri-implantitis. However, managing peri-implantitis with traditional treatment methods, such as nonsurgical debridement or surgery, is not always successful. Thus, novel strategies have been proposed to address these shortcomings. One strategy is the use of probiotics as antimicrobial agents since they are considered safe for humans and the environment. Specifically, the probiotic Lactococcus lactis produces nisin, which has been used worldwide for food preservation. The objective of this study was to determine whether nisin and the wild-type (WT) nisin-producing L. lactis probiotic can disrupt oral pathogenic biofilms and promote a healthier oral microbiome within these oral biofilms on titanium discs. Using confocal imaging and 16S rRNA sequencing, this study revealed that nisin and WT L. lactis probiotic disrupt oral pathogenic biofilms in a peri-implantitis setting in vitro. More specifically, nisin decreased the viability of the pathogen-spiked biofilms dose-dependently from 62.53 ± 3.69% to 54.26 ± 3.35% and 44.88 ± 2.98%, respectively. Similarly, 105 CFU/mL of WT L. lactis significantly decreased biofilm viability to 52.45 ± 3.41%. Further, both treatments shift the composition, relative abundance, and diversity levels of these biofilms towards healthy control levels. A total of 1 µg/mL of nisin and 103 CFU/mL of WT L. lactis were able to revert the pathogen-mediated changes in the Proteobacteria (from 80.5 ± 2.9% to 75.6 ± 2.0%, 78.0 ± 2.8%, and 75.1 ± 5.3%, respectively) and Firmicutes (from 11.6 ± 1.6% to 15.4 ± 1.3%, 13.8 ± 1.8%, and 13.7 ± 2.6%, respectively) phyla back towards control levels. Thus, nisin and its nisin-producing L. lactis probiotic may be useful in treating peri-implantitis by promoting healthier oral biofilms, which may be useful for improving patient oral health.
Transcriptomic Analysis Reveals the Role of tmRNA on Biofilm Formation in Bacillus subtilis
Authors: Xu Shanshan , Cao Qianqian , Liu Zengzhi , Chen Junpeng , Yan Peiguang , Li Bingyu , Xu Ying
Published: July 2022

Bacillus strains are widely distributed in terrestrial and marine environments, and some of them are used as biocontrol organisms for their biofilm-formation ability. In Bacillus subtilis, biofilm formation is fine-tuned by a complex network, a clear understanding of which still requires study. In bacteria, tmRNA, encoded by the ssrA gene, catalyzes trans-translation that can rescue ribosomes stalled on mRNA transcripts lacking a functional stop codon. tmRNA also affects physiological bioprocesses in some bacteria. In this study, we constructed a ssrA mutant in B. subtilis and found that the biofilm formation in the ssrA mutant was largely impaired. Moreover, we isolated a biofilm-formation suppressor of ssrA, in which the biofilm formation was restored to a level even stronger than that in the wild type. We further performed RNAseq assays with the wild type, ssrA mutant, and suppressor of ssrA for comparisons of their transcriptomes. By analyzing the transcriptomic data, we predicted the possible functions of some differentially expressed genes (DEGs) in the tmRNA regulation of biofilm formation in B. subtilis. Finally, we found that the overexpression of two DEGs, acoA and yhjR, could restore the biofilm formation in the ssrA mutant, indicating that AcoA and YhjR were immediate regulators involved in the tmRNA regulatory web controlling biofilm formation in B. subtilis. Our data can improve the knowledge about the molecular network involved in Bacillus biofilm formation and provide new targets for manipulation of Bacillus biofilms for future investigation.
Complex Trophic Interactions in an Acidophilic Microbial Community
Authors: Weithoff Guntram , Bell Elanor M.
Published: July 2022

Extreme habitats often harbor specific communities that differ substantially from non-extreme habitats. In many cases, these communities are characterized by archaea, bacteria and protists, whereas the number of species of metazoa and higher plants is relatively low. In extremely acidic habitats, mostly prokaryotes and protists thrive, and only very few metazoa thrive, for example, rotifers. Since many studies have investigated the physiology and ecology of individual species, there is still a gap in research on direct, trophic interactions among extremophiles. To fill this gap, we experimentally studied the trophic interactions between a predatory protist (Actinophrys sol, Heliozoa) and its prey, the rotifers Elosa woralli and Cephalodella sp., the ciliate Urosomoida sp. and the mixotrophic protist Chlamydomonas acidophila (a green phytoflagellate, Chlorophyta). We found substantial predation pressure on all animal prey. High densities of Chlamydomonas acidophila reduced the predation impact on the rotifers by interfering with the feeding behaviour of A. sol. These trophic relations represent a natural case of intraguild predation, with Chlamydomonas acidophila being the common prey and the rotifers/ciliate and A. sol being the intraguild prey and predator, respectively. We further studied this intraguild predation along a resource gradient using Cephalodella sp. as the intraguild prey. The interactions among the three species led to an increase in relative rotifer abundance with increasing resource (Chlamydomonas) densities. By applying a series of laboratory experiments, we revealed the complexity of trophic interactions within a natural extremophilic community.
Identification of Nematicidal Metabolites from Purpureocillium lavendulum
Authors: Liu Rui , Bao Zheng-Xue , Li Guo-Hong , Li Chun-Qiang , Wang Shao-Lin , Pan Xue-Rong , Zhang Ke-Qin , Zhao Pei-Ji
Published: July 2022

Purpureocillium lavendulum is a fungus with promising biocontrol applications. Here, transcriptome data acquired during the infection of Caenorhabditis elegans by Purpureocillium lavendulum showed that the transcription of metabolite synthesis genes was significantly up-regulated after 24 and 48 h of the fungus-nematode interaction. Then, the up-regulated transcription level of lipoxygenase was confirmed by RT-qPCR. The ultra-performance liquid chromatography-mass spectrometry (UPLC-MS) analysis of differential metabolites revealed that this interaction resulted in the emergence of new metabolites or enhanced the production of metabolites. The results of the UPLC-MS analysis and the nematicidal assay were used to establish optimal culturing conditions under which 12 metabolites, including 3 hydroxylated C18 fatty acids and 9 steroids, were isolated and identified. Among them, hydroxylated fatty acids showed pronounced nematicidal activity against Meloidogyne incognita, and two degradative sterols showed chemotaxis activity to M. incognita. This study lays a foundation for the function of lipoxygenase and its products during the infection of Purpureocillium lavendulum.
Experimental Test and Field Observations of an Electric Potential Monitoring Device for Dynamic Hazards during Mining Activities
Authors: Niu Yue , Wang Enyuan , Li Zhonghui , Shan Tiancheng , Wang Mingfu , Wang Jiali , Wang Honghao , Liu Hongchang , Ding Junhai , Wang Jingkun , Luo Feiyang , Shi Wei
Published: July 2022

The EP (electric potential) signals can be generated during the deformation and fracture process of coal and rock mass. Meanwhile, the EP response is closely related to its stress state and damage evolution, which is expected to be used in monitoring and coal and rock dynamic disaster hazards. Based on this, this paper developed an EP monitoring device for mining to continuously monitor the temporal response characteristics and spatial distribution of coal seam internal EP signals in real time. Further, the experimental tests were carried out, whose results showed that the device has high monitoring sensitivity and little error for the EP signals and can reveal the loading state and damage degree of the coal and rock specimens during the deformation and fracture process. Moreover, the tests and application of EP monitoring were carried out during mining activities in the field. The results showed that the EP signals fluctuate during the coal mining stage and remain relatively stable during the maintenance stage. When the abnormal mining stress or the coal cannon phenomenon occurs, the intensity of EP signals increases rapidly and fluctuates violently, which has precursory response information for the hazards of dynamic disasters. Considering the advantages of sensitive response and nearly non-destructive monitoring, the study results can provide key monitoring equipment and research basis for field testing the EP signals during the mining process, to monitor and forecast the hazards of coal and rock dynamic disasters.
The Influence of Blue and Red Light on Seed Development and Dormancy in Nicotiana tabacum L.
Authors: Cocco Emma , Farci Domenica , Haniewicz Patrycja , Schröder Wolfgang P. , Maxia Andrea , Piano Dario
Published: July 2022

The correct development of seeds is a pivotal requirement for species preservation. This process depends on the balance between sensing the environmental stimuli/stressors and hormone-mediated transduction, which results in physiological responses. The red and blue regions of the electromagnetic spectrum are known to influence seed dormancy and germination. Here, we report on the effects induced by the blue (peak at 430 nm) and red (peak at 650 nm) regions of the electromagnetic spectrum on seeds from photo- and skotomorphogenetic capsules developed under white, blue, or red light. Regardless of exposure, seeds from skotomorphogenetic capsules showed an almost absent dormancy in association with altered germination kinetics. Conversely, in seeds from photomorphogenetic capsules, the exposure to the blue region induced skotomorphogenetic-like effects, while the exposure to the whole visible range (350–750 nm), as well as to only the red region, showed a dose-related trend. The observed differences appeared to be dependent on the wavelengths in the red and to be based on transduction mechanisms taking place in fruits. While the molecular bases of this differential effect need to be clarified, the results hint at the role played by different light wavelengths and intensities in seed development and germination. These findings may be relevant for applications in crop production and species safeguarding.
Ophthalmic Manifestations among HIV Patients at the Main Tertiary Hospital in Freetown, Sierra Leone: A Cross-Sectional Study
Authors: Mustapha Jalikatu , Namanga Enanga Sonia , Idriss Baimba , Sesay Daniel , Jiba Darlinda F. , Russell James B. W. , Vandy Mathew J. , Deen Gibrilla F. , Yendewa George A. , Lakoh Sulaiman
Published: July 2022

Ophthalmic diseases are common among people living with HIV (PLHIV) in developing countries. However, there are currently no published studies on ophthalmic complications among PLHIV in Sierra Leone. We conducted a cross-sectional study of PLHIV presenting at Connaught Hospital in Freetown, Sierra Leone from January through March 2020. Logistic regression was used to identify associations between ophthalmic manifestations and potential risk factors. A total of 103 PLHIV were studied (78.6% female, median age 41 years, 100% treatment-experienced). The median CD4 cell count was 374 cells/mm3 and 76.7% were virologically suppressed. Overall, 44.7% of study participants had at least one ophthalmic complication and 51.5% had poor visual acuity in at least one eye. The most common conditions were dry eye (21.4%), cataract (20.4%), blepharitis (10.7%), nucleosclerosis (6.8%), conjunctivitis (5.8%), penguecula (5.8%), toxoplasmic retinochoroiditis (3.9%), and posterior vitreous detachment (2.9%). In multivariate logistic regression analysis, poor visual acuity (adjusted odds (aOR) 2.75, 95% confidence interval (CI) [1.12–6.78]; p = 0.040) and CD4 cell count < 100 cells/mm3 (aOR 3.91, 95% CI [1.07–14.31]; p = 0.028) were independently associated with ophthalmic disease. A high proportion of PLHIV in this study had ophthalmic complications. This calls for greater integration of HIV and ophthalmologic care.
Phototherapy-Based Treatment for Sexually Transmitted Infections—Shining Light into Unexplored Territory
Authors: Mammari Nour , Hamblin Michael R. , Rauger Pauline , Boyer Laurence , Varbanov Mihayl
Published: July 2022

New therapeutic strategies are urgently needed to overcome drawbacks in the treatment of some infections, particularly sexually transmitted infections (STI). STIs are easily spread by the transmission of various bacteria, viruses, and parasites with some of the infections being incurable or even lethal, leading to a serious impact on reproductive health worldwide. Phototherapy (PT) is a major therapeutic approach based on the controlled administration of light in the visible, near infrared, or UV spectrum, with or without the application of an external photosensitizer. Despite the fact that PT has not been explored to its full potential in the control of STIs, it has already demonstrated good clinical response rates and lower recurrence rates in genital infections. For instance, increasing evidence has demonstrated that 5-aminolevulinic acid photodynamic therapy (5-ALA-PDT) is effective in the treatment of condyloma acuminatum (CA), by eliminating the causative latent human papillomavirus (HPV) infection, and also in the antiviral treatment of recurrent genital herpes simplex virus (HSV) infections. The clinical application of PDT is a new treatment for oral fungal infection caused by Candida albicans in adult acquired immune deficiency syndrome (AIDS) patients, with human immunodeficiency virus (HIV), and could also be used for genital fungal infections. Another antimicrobial PT strategy, water-filtered infrared A combined with visible light irradiation, has been shown to be effective against genital Chlamydia trachomatis bacterial infection, and an optical nano-genosensor has been designed for the diagnosis of trichomoniasis, a parasitic Trichomonas vaginalis infection. This review aims to summarize the published evidence for the effectiveness of PT in the treatment of STIs, and for the suppression of STI-related pathogens of various types.
Risk management system of innovative programs within the framework of corporate governance of retail chain organizations and improving its efficiency
Authors: Vetrova A. Yu.
Published: July 2022

The article is devoted to the study of the risk management system of innovative programs within the corporate governance of retail chain organizations. In the course of the study, the following concepts were considered: retail network organization, innovation program and risks. As a result of the conducted research, it was revealed that improving the efficiency of corporate management of innovative programs is achieved by improving risk management, as well as innovative and strategic management of retail chain organizations.
Questions of the relationship between rational nutrition and quality of life in Russia
Authors: Levina E. V. , Golikova D. A.
Published: July 2022

The subject of the research is the attitude of students to rational nutrition as a component of the quality of life. The purpose of this article is to identify the attitude of students to rational nutrition as a component of the quality of life in order to develop recommendations for improving its level. Methodology. Within the framework of the research conducted by the author of the article, the following theories, methods, technologies and approaches were used: qualitative analysis of the works of domestic and foreign scientists devoted to the study of the sociology of nutrition, the concept of rationality and rational choice theories, as well as concepts of post-industrial society; methods of analysis and synthesis, classification and generalization in highlighting the general and particular in determining the quality problem the lives and places of rational nutrition in the life of students; methods of sociological research such as focus group. Results. In the presented article, the authors analyzed the directions of studying rationality, nutrition and quality of life as an economic category. The article offers recommendations to improve its level in a post-industrial society. Application. The conclusions and results obtained can be proposed for further study, analysis and evaluation of the place of rational nutrition in the life of students, including representatives of educational institutions.