bluuebunny/crossref_metadata_2025 huggingface dataset:
A Hybrid Multi-Objective Optimization Method Based on NSGA-II Algorithm and Entropy Weighted TOPSIS for Lightweight Design of Dump Truck Carriage
Authors: Jiang Rongchao , Ci Shukun , Liu Dawei , Cheng Xiaodong , Pan Zhenkuan
Published: August 2021

The lightweight design of vehicle components is regarded as a complex optimization problem, which usually needs to achieve two or more optimization objectives. It can be firstly solved by a multi-objective optimization algorithm for generating Pareto solutions, before then seeking the optimal design. However, it is difficult to determine the optimal design for lack of engineering knowledge about ideal and nadir values. Therefore, this paper proposes a multi-objective optimization procedure combined with the NSGA-II algorithm with entropy weighted TOPSIS for the lightweight design of the dump truck carriage. The finite element model of the dump truck carriage was firstly developed for modal analysis under unconstrained free state and strength analysis under the full load and lifting conditions. On this basis, the multi-objective lightweight optimization of the dump truck carriage was carried out based on the Kriging surrogate model and the NSGA-II algorithm. Then, the entropy weight TOPSIS method was employed to select the optimal design of the dump truck from Pareto solutions. The results show that the optimized dump truck carriage achieves a remarkable mass reduction of 81 kg, as much as 3.7%, while its first-order natural frequency and strength performance are slightly improved compared with the original model. Accordingly, the proposed procedure provides an effective way for vehicle lightweight design.
Digital Twin-Driven Mating Performance Analysis for Precision Spool Valve
Authors: Tang Wenbin , Xu Guangshen , Zhang Shoujing , Jin Shoufeng , Wang Runxiao
Published: August 2021

The precision spool valve is the core component of the electro-hydraulic servo control system, and its performance has an important influence on the flight control of aviation and aerospace products. The non-uniform surface topography error causes a non-uniform mating gap field inside the spool valve, which causes oil leakage and leads to deterioration of the spool valve performance. However, the current oil leakage calculation method only considers the influence of size errors, which is not comprehensive. Thus, how to characterize the mating behavior of the spool valve and its effect on oil leakage with consideration of surface topography errors is the key to evaluating the performance of the spool valve. This paper proposes a new way of analyzing the mating performance of precision spool valves, which considers the surface topography errors based on digital twin technology. Firstly, a general framework for the analysis of mating performance of precision spool valve based on a digital twin is proposed. Then, key technologies of assembly interface geometry modeling, matching behavior modeling and performance analysis are studied. Finally, a quantitative correlation between the mating parameters and the oil leakage of the precision spool valve is revealed. The method is tested on a practical case. This proposed method can provide theoretical support for the accurate prediction and evaluation of the mating performance of the precision spool valve.
Numerical Investigation of Nozzle Jet Flow in a Pelton Microturbine
Authors: Nedelcu Dorian , Cojocaru Vasile , Avasiloaie Raoul-Cristian
Published: August 2021

The characterization of flow through Pelton hydro turbines allows the optimization of their operation and maximization of energy performance. The flow in the injector of Pelton turbines and in the free jet area (the area from the injector outlet surface to the runner bucket inlet surface) is influenced by several parameters: the geometry of injector components (nozzle and injector spear), the injector opening, and the turbine head. The parameters of the free jet flow (velocity distribution, pressure distribution, and jet spread) are reflected in the turbine efficiency. The research presented in this paper focuses on the numerical characterization of flow in the injector and the free jet of a Pelton microturbine. Three injector geometries were considered, with different nozzle diameters: 13.3 mm, 14.4 mm, and 16.3 mm. For each of these geometries, the flow was analyzed for five values of turbine head (H = 15 m, H = 20 m, H = 25 m, H = 30 m, H = 35 m) and six values of injector opening (S = 3 mm, S = 6 mm, S = 9 mm, S = 12 mm, S = 15 mm, S = 18 mm). The results of numerical simulations were used to plot injector flow-rate characteristics and injector force characteristics (the resultant force on the injector spear and the resultant force on the injector nozzle). The highest influence on the flow rate variation is given by the variation of turbine head, followed by the variation of the injector opening and the variation of the nozzle diameter. Increasing the nozzle diameter accentuates the variation of the flow rate versus the turbine head. The variation of axial velocity and pressure in the free jet is presented for four sections parallel to the outlet section of the injector. The injector openings that generate the highest values of velocity/pressure on the runner inlet surface are highlighted. The results allow optimization of functional parameters for increasing turbine efficiency and optimizing the design process of Pelton microturbines.
An Approach to Measure the Performance and the Efficiency of Future Airport Infrastructure
Authors: Nieto Maria Rosa , Carmona-Benítez Rafael Bernardo
Published: August 2021

The aim of this paper is to design an approach to evaluate the expected efficiency and performance of future airport infrastructure. First, an airport sampling method to select similar airports is developed based on socioeconomic and operational airport variables that are summarized in a proxy variable; second, the ARIMA-GARCH-Bootstrap method is applied to forecast the selected outputs (PAX and ATMS) whilst the selected inputs (Cities, Gates, Runaways, Airport Size, Pax carriers, and Num. of employees) remain constant; and third, the VRS-OO and the CRS-OO DEA models are implemented to evaluate the efficiency and performance of the airports in the current and future years. The proposed approach is used to evaluate the future airport infrastructure of the new Mexico City Airport against 19 representative worldwide airport hubs. The proposed approach is applied to analyze the Mexico City Airport multi-airport system infrastructure as a case study. The results show that this multi-airport system requires more airside infrastructure that must be added by the new Mexico City Airport, airlines should operate aircrafts with more capacity to serve more PAX per ATM, and airlines must open new connections at the new Mexico City Airport to increase the expected efficiency and performance of this multi-airport system.
Spectra of Elliptic Operators on Quantum Graphs with Small Edges
Authors: Borisov Denis I.
Published: August 2021

We consider a general second order self-adjoint elliptic operator on an arbitrary metric graph, to which a small graph is glued. This small graph is obtained via rescaling a given fixed graph γ by a small positive parameter ε. The coefficients in the differential expression are varying, and they, as well as the matrices in the boundary conditions, can also depend on ε and we assume that this dependence is analytic. We introduce a special operator on a certain extension of the graph γ and assume that this operator has no embedded eigenvalues at the threshold of its essential spectrum. It is known that under such assumption the perturbed operator converges to a certain limiting operator. Our main results establish the convergence of the spectrum of the perturbed operator to that of the limiting operator. The convergence of the spectral projectors is proved as well. We show that the eigenvalues of the perturbed operator converging to limiting discrete eigenvalues are analytic in ε and the same is true for the associated perturbed eigenfunctions. We provide an effective recurrent algorithm for determining all coefficients in the Taylor series for the perturbed eigenvalues and eigenfunctions.
High-Dimensional Mahalanobis Distances of Complex Random Vectors
Authors: Dai Deliang , Liang Yuli
Published: August 2021

In this paper, we investigate the asymptotic distributions of two types of Mahalanobis distance (MD): leave-one-out MD and classical MD with both Gaussian- and non-Gaussian-distributed complex random vectors, when the sample size n and the dimension of variables p increase under a fixed ratio c=p/n→∞. We investigate the distributional properties of complex MD when the random samples are independent, but not necessarily identically distributed. Some results regarding the F-matrix F=S2−1S1—the product of a sample covariance matrix S1 (from the independent variable array (be(Zi)1×n) with the inverse of another covariance matrix S2 (from the independent variable array (Zj≠i)p×n)—are used to develop the asymptotic distributions of MDs. We generalize the F-matrix results so that the independence between the two components S1 and S2 of the F-matrix is not required.
Pontryagin Maximum Principle for Distributed-Order Fractional Systems
Authors: Ndaïrou Faïçal , Torres Delfim F. M.
Published: August 2021

We consider distributed-order non-local fractional optimal control problems with controls taking values on a closed set and prove a strong necessary optimality condition of Pontryagin type. The possibility that admissible controls are subject to pointwise constraints is new and requires more sophisticated techniques to include a maximality condition. We start by proving results on continuity of solutions due to needle-like control perturbations. Then, we derive a differentiability result on the state solutions with respect to the perturbed trajectories. We end by stating and proving the Pontryagin maximum principle for distributed-order fractional optimal control problems, illustrating its applicability with an example.
Inertial Extragradient Methods for Solving Split Equilibrium Problems
Authors: Suantai Suthep , Petrot Narin , Khonchaliew Manatchanok
Published: August 2021

This paper presents two inertial extragradient algorithms for finding a solution of split pseudomonotone equilibrium problems in the setting of real Hilbert spaces. The weak and strong convergence theorems of the introduced algorithms are presented under some constraint qualifications of the scalar sequences. The discussions on the numerical experiments are also provided to demonstrate the effectiveness of the proposed algorithms.
Alternating Polynomial Reconstruction Method for Hyperbolic Conservation Laws
Authors: Lin Shijian , Luo Qi , Leng Hongze , Song Junqiang
Published: August 2021

We propose a new multi-moment numerical solver for hyperbolic conservation laws by using the alternating polynomial reconstruction approach. Unlike existing multi-moment schemes, our approach updates model variables by implementing two polynomial reconstructions alternately. First, Hermite interpolation reconstructs the solution within the cell by matching the point-based variables containing both physical values and their spatial derivatives. Then the reconstructed solution is updated by the Euler method. Second, we solve a constrained least-squares problem to correct the updated solution to preserve the conservation laws. Our method enjoys the advantages of a compact numerical stencil and high-order accuracy. Fourier analysis also indicates that our method allows a larger CFL number compared with many other high-order schemes. By adding a proper amount of artificial viscosity, shock waves and other discontinuities can also be computed accurately and sharply without solving an approximated Riemann problem.
Some Conditions on Trans-Sasakian Manifolds to Be Homothetic to Sasakian Manifolds
Authors: Deshmukh Sharief , Ishan Amira , Belova Olga , Al-Shaikh Suha B.
Published: August 2021

In this paper, we study 3-dimensional compact and connected trans-Sasakian manifolds and find necessary and sufficient conditions under which these manifolds are homothetic to Sasakian manifolds. First, four results in this paper deal with finding necessary and sufficient conditions on a compact and connected trans-Sasakian manifold to be homothetic to a compact and connected Sasakian manifold, and the fifth result deals with finding necessary and sufficient condition on a connected trans-Sasakian manifold to be homothetic to a connected Sasakian manifold. Finally, we find necessary and sufficient conditions on a compact and simply connected trans-Sasakian manifold to be homothetic to a compact and simply connected Einstein Sasakian manifold.
A New Birnbaum–Saunders Distribution and Its Mathematical Features Applied to Bimodal Real-World Data from Environment and Medicine
Authors: Reyes Jimmy , Arrué Jaime , Leiva Víctor , Martin-Barreiro Carlos
Published: August 2021

In this paper, we propose and derive a Birnbaum–Saunders distribution to model bimodal data. This new distribution is obtained using the product of the standard Birnbaum–Saunders distribution and a polynomial function of the fourth degree. We study the mathematical and statistical properties of the bimodal Birnbaum–Saunders distribution, including probabilistic features and moments. Inference on its parameters is conducted using the estimation methods of moments and maximum likelihood. Based on the acceptance–rejection criterion, an algorithm is proposed to generate values of a random variable that follows the new bimodal Birnbaum–Saunders distribution. We carry out a simulation study using the Monte Carlo method to assess the statistical performance of the parameter estimators. Illustrations with real-world data sets from environmental and medical sciences are provided to show applications that can be of potential use in real problems.
Extraction of Fatty Acids and Phenolics from Mastocarpus stellatus Using Pressurized Green Solvents
Authors: Cid Uxía , Rodríguez-Seoane Paula , Díaz-Reinoso Beatriz , Domínguez Herminia
Published: August 2021

Polyunsaturated fatty acids are well known for their protective properties in relation to different skin diseases. Although seaweeds possess a low lipid fraction, they could act as an alternative renewable source of polyunsaturated fatty acids whenever other valuable seaweed components are also valorized. In this study, a biorefinery process using Mastocarpus stellatus as a model seaweed was proposed. The process started with the supercritical carbon dioxide extraction of the lipid and phenolic fractions. The influence of pressure during extraction with pure supercritical CO2 was studied while operating at a selected temperature and solvent flow rate. Kinetic data obtained during the ethanol-modified supercritical CO2 extraction were fitted to the spline model. Sequential processing was proposed with (i) pure CO2 to obtain a product with 30% PUFA content and ω-3:ω-6 ratio 1:1, (ii) ethanol-modified CO2 to extract phenolics, and (iii) microwave-assisted subcritical water extraction operating under previously optimized conditions for the extraction of phenolics, carrageenan and protein fractions. The composition of the supercritical extracts showed potential for use in both dietary and topical applications in skin care products. The remaining solids are suitable for the extraction of other valuable fractions.
Validity of Clinical Assessment Using Clinical Symptoms and C-Reactive Protein for Therapeutic Response in Pyogenic Vertebral Osteomyelitis: Analysis Based on 18F-FDG-PET
Authors: Jeon Ikchan , Yu Dongwoo , Kong Eunjung
Published: August 2021

Backgroundand objectives: The clinical assessment of therapeutic response in pyogenic vertebral osteomyelitis (PVO) has been usually performed based on the changes of clinical symptoms and blood inflammatory markers. Recently, 18F-fluorodeoxyglucose positron emission tomography (18F-FDG-PET) has emerged as an alternative independent method. We analyzed the validity of the clinical assessment for detecting residual PVO based on 18F-FDG-PET. Materials and Methods: This study was conducted with 53 patients confirmed as lumbar PVO under retrospective design. All patients underwent clinical assessment using clinical symptoms and C-reactive protein (CRP) for therapeutic response after parenteral antibiotic therapy, which led to the decision of placement in the uncontrolled (group UC) or controlled (group C) group. The validity of clinical assessment was analyzed based on the cut-off values of FDG uptake for detecting residual PVO as references, which are already established in the previous literature. Results: The mean duration of parenteral antibiotic therapy and recurrence rate were 42.19 ± 15.84 (21–89) days and 9.4% (5/53), respectively. 18F-FDG-PETs were performed at 80 rounds of clinical assessment on 37.40 ± 13.15 (21–83) days of parenteral antibiotic therapy and divided: 31 into group UC and 49 into group C, according to the decisions of clinical assessment. Based on the cut-off values of FDG uptake, clinical assessment showed 48.4–58.1% of false positive for residual PVO in group UC. However, 18F-FDG-PET showed 8.2% (4/49) of false negative for residual PVO in group C, which led to recurrences. Conclusions: Clinical assessment using clinical symptoms and CRP for evaluating therapeutic response in PVO is still a useful method in terms of similar recurrence rate compared to 18F-FDG-PET. However, the high rate of false positive for residual PVO can prolong the use of unnecessary antibiotics and overall treatment period.
Human Mesenchymal Stem Cells Seeded on the Natural Membrane to Neurospheres for Cholinergic-like Neurons
Authors: Stricker Priscila , de Souza Dobuchak Daiany , Irioda Ana , Mogharbel Bassam , Franco Celia , de Souza Almeida Leite José , de Araújo Alyne , Borges Felipe , Herculano Rondinelli , de Oliveira Graeff Carlos , Chachques Juan , de Carvalho Katherine
Published: August 2021

This study aimed to differentiate human mesenchymal stem cells (hMSCs) from the human umbilical cord in cholinergic-like neurons using a natural membrane. The isolation of hMSCs from Wharton’s jelly (WJ) was carried out using “explant” and mononuclear cells by the density gradient from umbilical blood and characterized by flow cytometry. hMSCs were seeded in a natural functional biopolymer membrane to produce neurospheres. RT-PCR was performed on hMSCs and neurospheres derived from the umbilical cord. Neural precursor cells were subjected to a standard cholinergic-like neuron differentiation protocol. Dissociated neurospheres, neural precursor cells, and cholinergic-like neurons were characterized by immunocytochemistry. hMSCs were CD73+, CD90+, CD105+, CD34- and CD45- and demonstrated the trilineage differentiation. Neurospheres and their isolated cells were nestin-positive and expressed NESTIN, MAP2, ßIII-TUBULIN, GFAP genes. Neural precursor cells that were differentiated in cholinergic-like neurons expressed ßIII-TUBULIN protein and choline acetyltransferase enzyme. hMSCs seeded on the natural membrane can differentiate into neurospheres, obtaining neural precursor cells without growth factors or gene transfection before cholinergic phenotype differentiation.
Effects of Steroids and Tocilizumab on the Immune Response Profile of Patients with COVID-19-Associated ARDS Requiring or Not Veno-Venous Extracorporeal Membrane Oxygenation
Authors: Fanelli Vito , Montrucchio Giorgia , Sales Gabriele , Simonetti Umberto , Bonetto Chiara , Rumbolo Francesca , Mengozzi Giulio , Urbino Rosario , Pizzi Costanza , Richiardi Lorenzo , Cappello Paola , Brazzi Luca
Published: August 2021

Veno-venous extracorporeal membrane oxygenation (VV-ECMO) is a life-saving rescue therapy in patients with Acute Respiratory Distress Syndrome (ARDS). ECMO has been associated with development of lymphocytopenia that is also common in COVID-19. Hyperinflammation may complicate SARS-CoV-2 pneumonia, prompting therapy with steroids and immunomodulatory drugs. We aimed to evaluate the association of therapies such as steroids and Tocilizumab with trajectories of the total leukocytes, lymphocyte subpopulation count, and inflammatory and fibrinolysis markers in COVID-19-related ARDS, requiring or not VV-ECMO support. The association of the trajectories of the leukocytes, lymphocyte subpopulation count, and inflammatory and fibrinolysis markers with treatment with steroids (Steroids), Tocilizumab (Tocilizumab), both drugs (Steroids + Tocilizumab), and absence of treatment (No Treatment) were analyzed using mixed effects regression models, where ECMO was considered as a potential effect modifier. One hundred and thirty-nine leukocyte and eighty-one lymphocyte subpopulation counts were obtained from thirty-one patients who required (VV-ECMO, N = 13) or not (no VV-ECMO, N = 18) extracorporeal support. In both groups, treatment with Steroids + Tocilizumab was independently associated with a significant reduction of 46% and 67% in total lymphocytes, 22% and 60% in CD3+, and 61% and 91% in CD19+ (B lymphocytes) compared to those obtained without treatment, respectively. In the no VV-ECMO group, Tocilizumab was associated with a 79% increase in total lymphocytes and with a reduction in procalcitonin compared to no treatment. CD45+, CD3+CD4+ (Th cell), CD3+CD8+, CD4+/CD8+, the NK cell subpopulation, neutrophils, monocytes, and basophils were significantly reduced by Steroids + Tocilizumab without an effect modification by VV-ECMO support. In critically ill COVID-19 patients with ARDS, concomitant therapies with steroids and Tocilizumab, beside mitigating the inflammation and fibrinolysis, could reduce the total leukocyte, lymphocyte, and subpopulation count. Moreover, the effect of Tocilizumab in increasing the total lymphocytes and reducing procalcitonin might be blunted by VV-ECMO.
Experimental Research and Simulation Analysis of Lightning Ablation Damage Characteristics of Megawatt Wind Turbine Blades
Authors: Zhao Yang , Yang Bin , Zhang Yao
Published: August 2021

In this paper, the damage mechanism of glass fiber reinforced composite (GFRC) under lightning strike by laying and inserting copper wires in the laminate was studied. The ablation characteristics of GFRC under different lightning current components were explored. Scanning electron microscope (SEM) was used to conduct the morphology analysis at the damaged area. The results show that the high temperature induced by lightning striking leads to resin pyrolysis, glass fiber (GF) sublimation, and stress waves, which results in fiber breakage and delamination. Then, a finite element (FE) thermal-electric coupling model for predicting the lightning ablation damage of GFRC was established. The comparison between the simulation and experimental results are in good agreement, which validate the effectiveness of the proposed FE model. The relationship between the lightning ablation area and the lightning current amplitude, charge amount, and specific energy in creeping discharge and through discharge was obtained by data fitting. The whole ablation damage process was revealed by FE simulation.
Friction Stir Spot Butt Welding of Dissimilar S45C Steel and 6061-T6 Aluminum Alloy
Authors: Gao Kun , Zhang Shengwei , Mondal Mounarik , Basak Soumyabrata , Hong Sung-Tae , Shim Heechan
Published: August 2021

Friction stir spot welding (FSSW) of dissimilar S45C steel and 6061-T6 aluminum alloy in a butt configuration is experimentally investigated. Butt spot welding is performed using a convex scrolled shoulder tool at different tool rotational speeds. FSSW butt joints are successfully fabricated by offsetting the tool to the steel side. The microstructures of the joints fabricated at three different tool rotational speeds are characterized using scanning electron microscopy and energy dispersive spectrometry. Microstructural analysis shows the presence of intermetallic compounds (IMCs) along the steel/aluminum interface. The thickness of the IMC layer and the tensile strength of the joint increase with increasing the tool rotational speed. The results of tensile tests and microstructural analysis show that the joint performance is closely related to the IMCs at the joint interface.
Effect of the Process Atmosphere Composition on Alloy 718 Produced by Laser Powder Bed Fusion
Authors: Pauzon Camille , Markström Andreas , Dubiez-Le Goff Sophie , Hryha Eduard
Published: August 2021

The detrimental effect of nitrogen and oxygen when it comes to the precipitation of the strengthening γ’’ and γ’ phases in Alloy 718 is well-known from traditional manufacturing. Hence, the influence of the two processing atmospheres, namely argon and nitrogen, during the laser powder bed fusion (L-PBF) of Alloy 718 parts was studied. Regardless of the gas type, considerable losses of both oxygen of about 150 ppm O2 (≈30%) and nitrogen on the level of around 400 ppm N2 (≈25%) were measured in comparison to the feedstock powder. The utilization of nitrogen as processing atmosphere led to a slightly higher nitrogen content in the as-built material—about 50 ppm—compared to the argon atmosphere. The presence of the stable nitrides and Al-rich oxides observed in the as-built material was related to the transfer of these inclusions from the nitrogen atomized powder feedstock to the components. This was confirmed by dedicated analysis of the powder feedstock and supported by thermodynamic and kinetic calculations. Rapid cooling rates were held responsible for the limited nitrogen pick-up. Oxide dissociation during laser–powder interaction, metal vaporization followed by oxidation and spatter generation, and their removal by processing atmosphere are the factors describing an important oxygen loss during L-PBF. In addition, the reduction of the oxygen level in the process atmosphere from 500 to 50 ppm resulted in the reduction in the oxygen level in as-built component by about 5%.
Enantioselective Quantification of Amphetamine and Metabolites in Serum Samples: Forensic Evaluation and Estimation of Consumption Time
Authors: Losacker Moritz , Kraemer Michael , Philipsen Alexandra , Duecker Kristina , Dreimueller Nadine , Engelmann Jan , Roehrich Joerg , Hess Cornelius
Published: August 2021

In forensic toxicology, amphetamine intoxications represent one of the most common case groups and present difficult questions for toxicologists. Estimating the time of consumption and the current influence of the stimulant is particularly difficult when only total amphetamine concentrations are considered. Stereoselective analysis and the consideration of metabolites can provide valuable information to facilitate interpretation. An enantioselective liquid chromatography−tandem mass spectrometry (LC-MS/MS) method for detection of amphetamine, norephedrine and 4-hydroxyamphetamine was developed. Validation showed satisfactory selectivity, sensitivity, linearity (0.5–250 ng/mL), precision and accuracy for all enantiomers. The method was applied to a collective of 425 forensic serum samples and 30 serum samples from psychiatric inpatients stating their last time of amphetamine consumption. Norephedrine and 4-hydroxyamphetamine were detected more frequently at higher amphetamine concentrations and at lower amphetamine (R)/(S) concentration ratios, possibly indicating recent consumption. Mean (R)/(S) ratio of amphetamine was 1.14, whereas higher ratios (mean 1.36) were found for amphetamine concentrations below 100 ng/mL. The (R)/(S) ratios of psychiatric inpatients significantly correlated with the reported time intervals to last consumption. The use of amphetamine (R)/(S) ratios and the simultaneous detection of metabolites are promising factors that can facilitate estimation of consumption time and current impairment.
Metabolite Profiling and Anti-Aging Activity of Rice Koji Fermented with Aspergillus oryzae and Aspergillus cristatus: A Comparative Study
Authors: Lee Hyunji , Lee Sunmin , Kyung Seoyeon , Ryu Jeoungjin , Kang Seunghyun , Park Myeongsam , Lee Choonghwan
Published: August 2021

Rice koji, used as a starter for maximizing fermentation benefits, produces versatile end products depending on the inoculum microbes used. Here, we performed metabolite profiling to compare rice koji fermented with two important filamentous fungus, Aspergillus oryzae and A. cristatus, during 8 days. The multivariate analyses showed distinct patterns of primary and secondary metabolites in the two kojis. The rice koji fermented with A. oryzae (RAO) showed increased α-glucosidase activity and higher contents of sugar derivatives than the one fermented with A. cristatus (RAC). RAC showed enhanced β-glucosidase activity and increased contents of flavonoids and lysophospholipids, compared to RAO. Overall, at the final fermentation stage (8 days), the antioxidant activities and anti-aging effects were higher in RAC than in RAO, corresponding to the increased metabolites such as flavonoids and auroglaucin derivatives in RAC. This comparative metabolomic approach can be applied in production optimization and quality control analyses of koji products.
An Oenothera biennis Cell Cultures Extract Endowed with Skin Anti-Ageing Activity Improves Cell Mechanical Properties
Authors: Ceccacci Sara , De Lucia Adriana , Tito Annalisa , Tortora Assunta , Falanga Danila , Arciello Stefania , Ausanio Giovanni , Di Cicco Chiara , Monti Maria Chiara , Apone Fabio
Published: August 2021

Skin aging is a very well-known process setting a gradual worsening of skin mechanical features due to a decline in the production of the extra-cellular matrix machinery and to a concurrent change in the contraction process. To slow this progression, it is crucial to induce the expression of several proteins able to promote elastic fibers formation and tissue repair. Here, the Oenothera biennis cell culture aqueous extract has been investigated from a chemical point of view and then it was tested in vitro, in cell, and in ex vivo experiments as adjuvant in counteracting skin aging. Accordingly, it has been shown that the Oenothera biennis extract was able, by increasing MYLK gene expression, to promote matrix collagen contraction, actin polymerization, and the production of essential ECM proteins.
In Vitro Antibacterial Activity of Selected Palestinian Medicinal Plants against Chlamydia trachomatis
Authors: Hamarsheh Omar , Amro Ahmad , Al-Zeer Munir A.
Published: August 2021

Chlamydia spp. are intracellular pathogens of humans and animals that cause a wide range of diseases such as blinding trachoma and sexually transmitted infections. According to the World Health Organization (WHO), there are more than 127 million new infections each year worldwide. Chlamydial urogenital infections can cause cervicitis, urethritis, pelvic inflammatory disease and infertility. From within an intracellular niche, termed an inclusion, the Chlamydiae complete their life cycle shielded from host defenses. The host cell defense response used to eliminate the pathogen must subvert this protective shield and is thought to involve the gamma interferon-inducible family of immunity related GTPase proteins and nitric oxide. Typically, azithromycin and doxycycline are the first line drugs for the treatment of chlamydial infections. Although C. trachomatis is sensitive to these antibiotics in vitro, currently, there is increasing bacterial resistance to antibiotics including multidrug-resistant C. trachomatis, which have been described in many instances. Therefore, alternative drug candidates against Chlamydia should be assessed in vitro. In this study, we tested and quantified the activity of plant extracts against Chlamydia-infected HeLa cells with C. trachomatis inclusions. The in vitro results show that post-treatment with Artemisia inculta Delile extract significantly inhibits Chlamydia infection compared to DMSO-treated samples. In conclusion, plant extracts may contain active ingredients with antichlamydial activity potential and can be used as alternative drug candidates for treatment of Chlamydia infection which has significant socio-economic and medical impact.
The Pheno- and Genotypic Characterization of Porcine Escherichia coli Isolates
Authors: Bernreiter-Hofer Tanja , Schwarz Lukas , Müller Elke , Cabal-Rosel Adriana , Korus Maciej , Misic Dusan , Frankenfeld Katrin , Abraham Kerstin , Grünzweil Olivia , Weiss Astrid , Feßler Andrea T. , Allerberger Franz , Schwarz Stefan , Szostak Michael P. , Ruppitsch Werner , Ladinig Andrea , Spergser Joachim , Braun Sascha D. , Monecke Stefan , Ehricht Ralf , Loncaric Igor
Published: August 2021

Escherichia (E.) coli is the main causative pathogen of neonatal and post-weaning diarrhea and edema disease in swine production. There is a significant health concern due to an increasing number of human infections associated with food and/or environmental-borne pathogenic and multidrug-resistant E. coli worldwide. Monitoring the presence of pathogenic and antimicrobial-resistant E. coli isolates is essential for sustainable disease management in livestock and human medicine. A total of 102 E. coli isolates of diseased pigs were characterized by antimicrobial and biocide susceptibility testing. Antimicrobial resistance genes, including mobile colistin resistance genes, were analyzed by PCR and DNA sequencing. The quinolone resistance-determining regions of gyrA and parC in ciprofloxacin-resistant isolates were analyzed. Clonal relatedness was investigated by two-locus sequence typing (CH clonotyping). Phylotyping was performed by the Clermont multiplex PCR method. Virulence determinants were analyzed by customized DNA-based microarray technology developed in this study for fast and economic molecular multiplex typing. Thirty-five isolates were selected for whole-genome sequence-based analysis. Most isolates were resistant to ampicillin and tetracycline. Twenty-one isolates displayed an ESBL phenotype and one isolate an AmpC β-lactamase-producing phenotype. Three isolates had elevated colistin minimal inhibitory concentrations and carried the mcr-1 gene. Thirty-seven isolates displayed a multi-drug resistance phenotype. The most predominant β-lactamase gene classes were blaTEM-1 (56%) and blaCTX-M-1 (13.71%). Mutations in QRDR were observed in 14 ciprofloxacin-resistant isolates. CH clonotyping divided all isolates into 51 CH clonotypes. The majority of isolates belonged to phylogroup A. Sixty-four isolates could be assigned to defined pathotypes wherefrom UPEC was predominant. WGS revealed that the most predominant sequence type was ST100, followed by ST10. ST131 was detected twice in our analysis. This study highlights the importance of monitoring antimicrobial resistance and virulence properties of porcine E. coli isolates. This can be achieved by applying reliable, fast, economic and easy to perform technologies such as DNA-based microarray typing. The presence of high-risk pathogenic multi-drug resistant zoonotic clones, as well as those that are resistant to critically important antibiotics for humans, can pose a risk to public health. Improved protocols may be developed in swine farms for preventing infections, as well as the maintenance and distribution of the causative isolates.
A Genomic and Transcriptomic Study on the DDT-Resistant Trichoderma hamatum FBL 587: First Genetic Data into Mycoremediation Strategies for DDT-Polluted Sites
Authors: Davolos Domenico , Russo Fabiana , Canfora Loredana , Malusà Eligio , Tartanus Małgorzata , Furmanczyk Ewa Maria , Ceci Andrea , Maggi Oriana , Persiani Anna Maria
Published: August 2021

Trichoderma hamatum FBL 587 isolated from DDT-contaminated agricultural soils stands out as a remarkable strain with DDT-resistance and the ability to enhance DDT degradation process in soil. Here, whole genome sequencing and RNA-Seq studies for T. hamatum FBL 587 under exposure to DDT were performed. In the 38.9 Mb-genome of T. hamatum FBL 587, 10,944 protein-coding genes were predicted and annotated, including those of relevance to mycoremediation such as production of secondary metabolites and siderophores. The genome-scale transcriptional responses of T. hamatum FBL 587 to DDT exposure showed 1706 upregulated genes, some of which were putatively involved in the cellular translocation and degradation of DDT. With regards to DDT removal capacity, it was found upregulation of metabolizing enzymes such as P450s, and potentially of downstream DDT-transforming enzymes such as epoxide hydrolases, FAD-dependent monooxygenases, glycosyl- and glutathione-transferases. Based on transcriptional responses, the DDT degradation pathway could include transmembrane transporters of DDT, antioxidant enzymes for oxidative stress due to DDT exposure, as well as lipases and biosurfactants for the enhanced solubility of DDT. Our study provides the first genomic and transcriptomic data on T. hamatum FBL 587 under exposure to DDT, which are a base for a better understanding of mycoremediation strategies for DDT-polluted sites.
Effect of Lactococcus lactis Strain Plasma on HHV-6 and HHV-7 Shedding in Saliva: A Prospective Observational Study
Authors: Miura Hiroki , Ihira Masaru , Kozawa Kei , Kawamura Yoshiki , Higashimoto Yuki , Hattori Fumihiko , Yoshikawa Tetsushi
Published: August 2021

HHV-6 and HHV-7 can reactivate in the salivary gland in response to various host stresses. Lactococcus lactis strain Plasma (LC-Plasma) can activate plasmacytoid dendritic cells (pDCs) and decrease viral infection. We investigated whether LC-Plasma intake could decrease HHV-6 and HHV-7 reactivation in the salivary gland. A total of 54 healthy volunteers were enrolled in this study. Participants took LC-Plasma granules daily for 6 weeks. Saliva samples were collected from subjects weekly for 4 weeks before (first), during (second), and after (third period) LC-Plasma intake. There was a 2-week interval between the first and second periods and a 3-week interval between the second and third periods. Mean salivary HHV-6 and HHV-7 DNA loads were compared among the three observation periods. In the first period (baseline data of viral DNA shedding), HHV-6 DNA shedding was significantly higher in subjects under 40 years old, and HHV-7 DNA shedding was significantly higher in males. HHV-6 and HHV-7 DNA loads did not significantly differ between periods. Meanwhile, in a subgroup analysis of the subjects under 40 years old, HHV-6 DNA load was significantly lower in the second period than in the first period. LC-Plasma decreases HHV-6 reactivation in the salivary glands in younger adults.
Molecular Characterization of Staphylococcus aureus Isolated from Raw Milk Samples of Dairy Cows in Manhiça District, Southern Mozambique
Authors: Nhatsave Nilsa , Garrine Marcelino , Messa Augusto , Massinga Arsénia J. , Cossa Anélsio , Vaz Raúl , Ombi Angelina , Zimba Tomás F. , Alfredo Hélder , Mandomando Inácio , Tchamo Cesaltina
Published: August 2021

Staphylococcal infections are among the most common foodborne diseases. We performed the antibiotic susceptibility and molecular characterization of S. aureus from milk samples of dairy cows in Manhiça District. We observed a high frequency of S. aureus (41%, 58/143), in which 71% (41/58) were from commercial farms and 29% (17/58) from smallholder farms. Half of the isolates (50%, 29/58) were resistant to at least one antibiotic, with higher rates of resistance to penicillin (43%, 25/58), followed by tetracycline (16%, 9/58). Multidrug-resistant and methicillin-resistant S. aureus isolates were rare (5%, 3/58 and 3%, 2/58, respectively). The genetic diversity was low, with predominance of human-adapted strains being: ST1/CC1-t5388 (78%) and ST152-t1299 (10%), followed by ST8/CC8-t1476 (5%) and ST5/CC5-t002 (3%) and lastly, ST508/CC45-t331 and ST152-t355, with 2% each. The Panton–Valentine leukocidin (PVL) gene was detected among 14% (8/58) of the isolates, while genes encoding staphylococcal enterotoxins were scarce (3%, 2/58). Our findings revealed a high frequency of S. aureus, with high rates of resistance to the antibiotics commonly used in veterinary and human medicine. Further investigations focusing on the molecular epidemiology of S. aureus from cattle and farmers will provide detailed insights on the genetic relatedness between the strains.
New Insights into Beta-Lactam Resistance of Streptococcus pneumoniae: Serine Protease HtrA Degrades Altered Penicillin-Binding Protein 2x
Authors: Peters Katharina , Schweizer Inga , Hakenbeck Regine , Denapaite Dalia
Published: August 2021

Reduced amounts of the essential penicillin-binding protein 2x (PBP2x) were detected in two cefotaxime-resistant Streptococcus pneumoniae laboratory mutants C405 and C606. These mutants contain two or four mutations in the penicillin-binding domain of PBP2x, respectively. The transcription of the pbp2x gene was not affected in both mutants; thus, the reduced PBP2x amounts were likely due to post-transcriptional regulation. The mutants carry a mutation in the histidine protein kinase gene ciaH, resulting in enhanced gene expression mediated by the cognate response regulator CiaR. Deletion of htrA, encoding a serine protease regulated by CiaR, or inactivation of HtrA proteolytic activity showed that HtrA is indeed responsible for PBP2x degradation in both mutants, and that this affects β-lactam resistance. Depletion of the PBP2xC405 in different genetic backgrounds confirmed that HtrA degrades PBP2xC405. A GFP-PBP2xC405 fusion protein still localized at the septum in the absence of HtrA. The complementation studies in HtrA deletion strains showed that HtrA can be overexpressed in pneumococcal cells to specific levels, depending on the genetic background. Quantitative Western blotting revealed that the PBP2x amount in C405 strain was less than 20% compared to parental strain, suggesting that PBP2x is an abundant protein in S. pneumoniae R6 strain.
Improvement of CO2 and Acetate Coupling into Lactic Acid by Genetic Manipulation of the Hyperthermophilic Bacterium Thermotoga neapolitana
Authors: Esercizio Nunzia , Lanzilli Mariamichela , Vastano Marco , Xu Zhaohui , Landi Simone , Caso Lucio , Gallo Carmela , Nuzzo Genoveffa , Manzo Emiliano , Fontana Angelo , d’Ippolito Giuliana
Published: August 2021

Capnophilic lactic fermentation (CLF) represents an attractive biotechnological process for biohydrogen production and synthesis of L-lactic acid from acetate and CO2. The present study focuses on a genetic manipulation approach of the Thermotoga neapolitana DSM33003 strain to enhance lactic acid synthesis by the heterologous expression of a thermostable acetyl-CoA synthetase that catalyses the irreversible acetate assimilation. Because of the scarcity of available genetic tools, each transformation step was optimized for T. neapolitana DSM33003 to cope with the specific needs of the host strain. Batch fermentations with and without an external source of acetate revealed a strongly increased lactate production (up to 2.5 g/L) for the recombinant strain compared to wild type. In the engineered bacterium, the assimilation of CO2 into lactic acid was increased 1.7 times but the hydrogen yield was impaired in comparison to the wild type strain. Analysis of fermentation yields revealed an impaired metabolism of hydrogen in the recombinant strain that should be addressed in future studies. These results offer an important prospective for the development of a sustainable approach that combines carbon capture, energy production from renewable source, and the synthesis of high value-added products, which will be addressed in future studies.
The Impact of Angiotensin-Converting Enzyme 2 (ACE2) Expression Levels in Patients with Comorbidities on COVID-19 Severity: A Comprehensive Review
Authors: Rodrigues Rui , Costa de Oliveira Sofia
Published: August 2021

Angiotensin-Converting Enzyme 2 (ACE2) has been proved to be the main host cell receptor for the binding of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus responsible for the COVID-19 pandemic. The SARS-CoV-2 spike (S) protein binds to ACE2 to initiate the process of replication. This enzyme is widely present in human organ tissues, such as the heart and lung. The pathophysiology of ACE2 in SARS-CoV-2 infection is complex and may be associated with several factors and conditions that are more severe in COVID-19 patients, such as age, male gender, and comorbidities, namely, cardiovascular diseases, chronic respiratory diseases, obesity, and diabetes. Here we present a comprehensive review that aims to correlate the levels of expression of the ACE2 in patients with comorbidities and with a poor outcome in COVID-19 disease. Significantly higher levels of expression of ACE2 were observed in myocardial and lung tissues in heart failure and COPD patients, respectively. An age-dependent increase in SARS2-CoV-2 receptors in the respiratory epithelium may be also responsible for the increased severity of COVID-19 lung disease in elderly people. Although the role of ACE2 is highlighted regarding the damage that can arise upon the SARS-CoV-2 invasion, there was no association observed between renin-angiotensin-aldosterone system (RAAS) inhibitors and the severity of COVID-19.
Secondary Sulfate Minerals from Thallium Mineralized Areas: Their Formation and Environmental Significance
Authors: Zhao Fengqi , Gu Shangyi
Published: August 2021

Thallium is a highly toxic metal and is predominantly hosted by sulfides associated with low-temperature hydrothermal mineralization. Weathering and oxidation of sulfides generate acid drainage with a high concentration of thallium, posing a threat to surrounding environments. Thallium may also be incorporated into secondary sulfate minerals, which act as temporary storage for thallium. We present a state-of-the-art review on the formation mechanism of the secondary sulfate minerals from thallium mineralized areas and the varied roles these sulfate minerals play in Tl mobility. Up to 89 independent thallium minerals and four unnamed thallium minerals have been documented. These thallium minerals are dominated by Tl sulfosalts and limited to several sites. Occurrence, crystal chemistry, and Tl content of the secondary sulfate minerals indicate that Tl predominantly occurs as Tl(I) in K-bearing sulfate. Lanmuchangite acts as a transient source and sink of Tl for its water-soluble feature, whereas dorallcharite, Tl-voltaite, and Tl-jarosite act as the long term source and sink of Tl in the surface environments. Acid and/or ferric iron derived from the dissolution of sulfate minerals may increase the pyrite oxidation process and Tl release from Tl-bearing sulfides in the long term.
In-Sn-Zn Oxide Nanocomposite Films with Enhanced Electrical Properties Deposited by High-Power Impulse Magnetron Sputtering
Authors: Sun Hui , Li Zhi-Yue , Chen Sheng-Chi , Liao Ming-Han , Gong Jian-Hong , Bai Zhamatuofu , Wang Wan-Xia
Published: August 2021

In-Sn-Zn oxide (ITZO) nanocomposite films have been investigated extensively as a potential material in thin-film transistors due to their good electrical properties. In this work, ITZO thin films were deposited on glass substrates by high-power impulse magnetron sputtering (HiPIMS) at room temperature. The influence of the duty cycle (pulse off-time) on the microstructures and electrical performance of the films was investigated. The results showed that ITZO thin films prepared by HiPIMS were dense and smooth compared to thin films prepared by direct-current magnetron sputtering (DCMS). With the pulse off-time increasing from 0 μs (DCMS) to 2000 μs, the films’ crystallinity enhanced. When the pulse off-time was longer than 1000 μs, In2O3 structure could be detected in the films. The films’ electrical resistivity reduced as the pulse off-time extended. Most notably, the optimal resistivity of as low as 4.07 × 10−3 Ω·cm could be achieved when the pulse off-time was 2000 μs. Its corresponding carrier mobility and carrier concentration were 12.88 cm2V−1s−1 and 1.25 × 1020 cm−3, respectively.