bluuebunny/crossref_metadata_2025 huggingface dataset:
Experimental Study of the Hydrodynamic Characteristics of a Submerged Floating Tunnel under Freak Wave (II: Time-Frequency Domain Study)
Authors: Pan Wenbo , Cui Cheng , He Meng
Published: May 2023

A freak wave is a spike in a random wave series and hence the local characteristics in the time-domain are of key importance. When freak waves act on moored floating structures, the dynamic responses of the structures in the time and frequency domains change interdependently in a short period of time. It is difficult to comprehensively and accurately describe this physical process using a single-dimensional analysis method, such as time-domain statistical analysis or frequency-domain spectral analysis. The wavelet analysis method, which can simultaneously provide the time-domain and frequency-domain joint information of the physical process, is used to discuss the time-frequency joint variation characteristics of the dynamic responses of a two-dimensional submerged floating tunnel under a freak wave. The time-frequency characteristics of the dynamic responses induced by the freak wave and the differences from the action under random waves are investigated, with a particular emphasis on the ‘convex variation’ characteristics of the dynamic responses under a freak wave. The results show that: (1) The wavelet analysis method can effectively describe the basic characteristics of the dynamic responses of the SFT under a freak wave and clearly distinguish the differences in dynamic responses under freak and random waves. (2) Freak waves have dynamic amplification effects, which are related to the freak wave parameter α1, on a two-dimensional SFT. Following the action of freak waves on a two-dimensional SFT, significant energy concentration occurs in the time-frequency spectrum of the dynamic response in a certain time and frequency range. The degree of energy concentration increases nonlinearly with an increase in α1, and a certain high-frequency energy appears in the time-frequency spectrum of the motion response. The maximum values of the time-frequency spectra of the dynamic responses under a freak wave are much larger than those under a random wave with the identical wave spectrum. (3) Following the action of a freak wave on a two-dimensional SFT, the generalised energy spectra of surge, heave, pitch, and mooring tensions have convex peak values, which occur simultaneous with the occurrence of the freak wave, and the convex parts significantly increase as α1. (4) The time lengths of the influence of a freak wave on the dynamic responses exceeded the freak wave period. With an increase in α1, the time ranges of the large values of the time-frequency spectra of surge, heave, pitch, and mooring tensions increase nearly linearly.
The Impact of Nutrition, Physical Activity, Beneficial Microbes, and Fecal Microbiota Transplant for Improving Health
Authors: Keathley Justine , White Jessica , Reid Gregor
Published: May 2023

The recognition that microbes are integral to human life has led to studies on how to manipulate them in favor of health outcomes. To date, there has been no conjoint recommendation for the intake of dietary compounds that can complement the ingested organisms in terms of promoting an improved health outcome. The aim of this review is to discuss how beneficial microbes in the form of probiotics, fermented foods, and donor feces are being used to manage health. In addition, we explore the rationale for selecting beneficial microbial strains and aligning diets to accommodate their propagation in the gut. A pilot clinical trial design is presented to examine the effects of probiotics and exercise in patients with phenylketonuria (PKU); it is the most common inborn error of amino acid metabolism, and it is a complication that requires lifelong dietary intervention. The example design is provided to illustrate the importance of using omics technology to see if the intervention elevates neuroactive biogenic amines in the plasma; increases the abundance of Eubacterium rectale, Coprococcus eutactus, Akkermansia muciniphila, or Butyricicoccus; and increases Escherichia/Shigella in the gut, all as markers of improved health. By emphasizing the combined importance of diet, microbial supplements, and the gut microbiome, we hope that future studies will better align these components, not only to improve outcomes, but also to enhance our understanding of the mechanisms.
Transcranial Electrical Stimulation for Associative Memory Enhancement: State-of-the-Art from Basic to Clinical Research
Authors: Bjekić Jovana , Manojlović Milica , Filipović Saša R.
Published: May 2023

Associative memory (AM) is the ability to bind new information into complex memory representations. Noninvasive brain stimulation (NIBS), especially transcranial electric stimulation (tES), has gained increased interest in research of associative memory (AM) and its impairments. To provide an overview of the current state of knowledge, we conducted a systematic review following PRISMA guidelines covering basic and clinical research. Out of 374 identified records, 41 studies were analyzed—twenty-nine in healthy young adults, six in the aging population, three comparing older and younger adults, as well as two studies on people with MCI, and one in people with Alzheimer’s dementia. Studies using transcranial direct current stimulation (tDCS), transcranial alternating current stimulation (tACS) as well as oscillatory (otDCS) and high-definition protocols (HD-tDCS, HD-tACS) have been included. The results showed methodological heterogeneity in terms of study design, stimulation type, and parameters, as well as outcome measures. Overall, the results show that tES is a promising method for AM enhancement, especially if the stimulation is applied over the parietal cortex and the effects are assessed in cued recall paradigms.
Nonlinear Finite Element Model for Bending Analysis of Functionally-Graded Porous Circular/Annular Micro-Plates under Thermomechanical Loads Using Quasi-3D Reddy Third-Order Plate Theory
Authors: Kim Jinseok , Nava Enrique , Rakici Semsi
Published: May 2023

A nonlinear finite element model for axisymmetric bending of micro circular/annular plates under thermal and mechanical loading was developed using quasi-3D Reddy third-order shear deformation theory. The developed finite element model accounts for a variation of material constituents utilizing a power-law distribution of a two-constituent material, three different porosity distributions through plate thickness, and geometrical nonlinearity. The modified couple stress theory was utilized to account for the strain gradient effects using a single material length scale parameter. Three different types of porosity distributions that have the same overall volume fraction but different enhanced areas were considered as a form of cosine functions. The effects of the material and porosity distribution, microstructure-dependency, the geometric nonlinearity, and various boundary conditions on the bending response of functionally-graded porous axisymmetric microplates under thermomechanical loads were studied using the developed nonlinear finite element model.
Preparation of MCS from Low-Grade Bauxite Desilication Lye and Adsorption of Heavy Metals
Authors: Chen Cheng , Chen Chaoyi , Li Junqi , Wang Gangan , Lin Xin , Ning Deyang
Published: May 2023

By utilizing low-grade bauxite desilication solution as raw material and adding lime after thermal reaction, adsorbent MCS was synthesized. X-ray diffraction, Brunauer–Emmett–Teller, Fourier transform infrared spectroscopy, and scanning electron microscopy were used to characterize the MCS, MCS-Pb, and MCS-Cu. The Freundlich model was found to be more suitable for isothermal adsorption, suggesting that the adsorption of Cu2+ and Pb2+ by MCS is not limited to monolayer adsorption. According to the results of the experiment, the maximum adsorption capacities of lead ion and copper ion were found to be Pb2+ (1921.506 mg/g) > Cu2+ (561.885 mg/g), and the adsorption was controlled by chemical reactions following pseudo-second-order kinetics. Electrolyte study results indicated that the presence of background electrolyte did not affect the adsorption of Cu2+ and Pb2+ by MCS.
Insights into the Contribution of Oxidation-Reduction Pretreatment for Mn0.2Zr0.8O2−δ Catalyst of CO Oxidation Reaction
Authors: Mishchenko Denis D. , Vinokurov Zakhar S. , Afonasenko Tatyana N. , Saraev Andrey A. , Simonov Mikhail N. , Gerasimov Evgeny Yu. , Bulavchenko Olga A.
Published: May 2023

A Mn0.2Zr0.8O2−δ mixed oxide catalyst was synthesized via the co-precipitation method and studied in a CO oxidation reaction after different redox pretreatments. The surface and structural properties of the catalyst were studied before and after the pretreatment using XRD, XANES, XPS, and TEM techniques. Operando XRD was used to monitor the changes in the crystal structure under pretreatment and reaction conditions. The catalytic properties were found to depend on the activation procedure: reducing the CO atmosphere at 400–600 °C and the reaction mixture (O2 excess) or oxidative O2 atmosphere at 250–400 °C. A maximum catalytic effect characterized by decreasing T50 from 193 to 171 °C was observed after a reduction at 400 °C and further oxidation in the CO/O2 reaction mixture was observed at 250 °C. Operando XRD showed a reversible reduction-oxidation of Mn cations in the volume of Mn0.2Zr0.8O2−δ solid solution. XPS and TEM detected the segregation of manganese cations on the surface of the mixed oxide. TEM showed that Mn-rich regions have a structure of MnO2. The pretreatment caused the partial decomposition of the Mn0.2Zr0.8O2−δ solid solution and the formation of surface Mn-rich areas that are active in catalytic CO oxidation. In this work it was shown that the introduction of oxidation-reduction pretreatment cycles leads to an increase in catalytic activity due to changes in the origin of active states.
Topology Optimization of the Clutch Lever Manufactured by Additive Manufacturing
Authors: Mikulikova Aleksandra , Mesicek Jakub , Karger Jan , Hajnys Jiri , Ma Quoc-Phu , Sliva Ales , Smiraus Jakub , Srnicek David , Cienciala Samuel , Pagac Marek
Published: May 2023

This article aims to review a redesign approach of a student racing car’s clutch lever component, which was topologically optimized and manufactured by Additive Manufacturing (AM). Finite Element Method (FEM) analysis was conducted before and after a Topology Optimization (TO) process in order to achieve equivalent stiffness and the desired safety factor for the optimized part. The redesigned clutch lever was manufactured by using AM–Selective Laser Melting (SLM) and printed from powdered aluminum alloy AlSi10Mg. The final evaluation of the study deals with the experimental test and comparison of the redesigned clutch lever with the existing part which was used in the previous racing car. Using TO as a main redesign tool and AM brought significant changes to the optimized part, especially the following: reduced mass of the component (10%), increased stiffness, kept safety factor above the 3.0 value and ensured the more aesthetic design and a good surface quality. Moreover, using TO and AM gave the opportunity to consolidate multi-part assembly into a single component manufactured by one manufacturing process that reduced the production time. The experimental results justified the simulation results and proved that even though the applied load was almost 1.5× higher than the assumed one, the maximum von Mises stress on the component was still below the yield limit of 220 MPa.
Geometric Design of a Low-Power Arcjet Constrictor and Determination of Velocity of Air-Based Plasma by Means of Analytical and Numerical Methods
Authors: Argumedo Teuffer Pedro José , Marron Ramirez Luis Enrique , Ituna-Yudonago Jean Fulbert , Arizpe Carreón Pablo Alejandro , Rodríguez Roman Carlos Manuel
Published: May 2023

The following research focuses on the analytical and numerical study of an arcjet constrictor. In order to perform these analyses, a geometric design of the constrictor was proposed. The analytical study considers mathematical models proposed by Stine and Watson, related to the properties of air propellants, such as the specific enthalpy, electric conductivity, thermal conductivity, and specific heat. The numerical study considered the equations for mass, momentum, energy, and electricity that describe the interaction between the electric arc and the fluid flow. These equations were solved in ANSYS FLUENT software, in which the κ-ϵ turbulence and the magnetohydrodynamic (MHD) models were used. The external routines, including user-defined functions, user-defined scalars, and user-defined memory were implemented in C++ language for source terms and linked to ANSYS FLUENT. The velocity profiles were obtained analytically for the electric arc temperatures of 9000 K, 10,000 K, and 11,000 K with peak magnitudes of 2960 m/s, 3350 m/s, and 3100 m/s, respectively, at the outlet of the constrictor. It was observed from the numerical results that the velocity magnitude of the air-based plasma inside the constrictor increases as the temperature of the electric arc rises up to 10,000 K However, above 10,000 K, the velocity magnitude decreases because at this temperature level, the air particles become completely ionized, and the specific heat of the air-based plasma decreases. The numerical simulation produced velocity profile magnitudes at two different electric arc temperatures (9000 K and 10,000 K) with peak magnitudes of 2400 m/s and 2900 m/s, respectively, at the outlet of the constrictor. The numerical and analytical results were very close with an error of 16.327%.
q-Fractional Langevin Differential Equation with q-Fractional Integral Conditions
Authors: Wang Wuyang , Khalid Khansa Hina , Zada Akbar , Ben Moussa Sana , Ye Jun
Published: May 2023

The major goal of this manuscript is to investigate the existence, uniqueness, and stability of a q-fractional Langevin differential equation with q-fractional integral conditions. We demonstrate the existence and uniqueness of the solution to the proposed q-fractional Langevin differential equation using the Banach contraction principle and Schaefer’s fixed-point theorem. We also elaborate on different kinds of Ulam stability. The theoretical outcomes are verified by examples.
Amplitude and Phase Angle of Oscillatory Heat Transfer and Current Density along a Nonconducting Cylinder with Reduced Gravity and Thermal Stratification Effects
Authors: Ullah Zia , Jabeen Nawishta , Khan Muhammad Usman
Published: May 2023

Due to excessive heating, various physical mechanisms are less effective in engineering and modern technologies. The aligned electromagnetic field performs as insulation that absorbs the heat from the surroundings, which is an essential feature in contemporary technologies, to decrease high temperatures. The major goal of the present investigation is to use magnetism perpendicular to the surface to address this issue. Numerical simulations have been made of the MHD convective heat and amplitude problem of electrical fluid flow down a horizontally non-magnetized circular heated cylinder with reduced gravity and thermal stratification. The associated non-linear PDEs that control fluid motion can be conveniently represented using the finite-difference algorithm and primitive element substitution. The FORTRAN application was used to compute the quantitative outcomes, which are then displayed in diagrams and table formats. The physical features, including the phase angle, skin friction, transfer of heat, and electrical density for velocity description, the magnetic characteristics, and the temperature distribution, coupled by their gradients, have an impact on each of the variables in the flow simulation. In the domains of MRI resonant patterns, prosthetic heartvalves, interior heart cavities, and nanoburning devices, the existing magneto-hydrodynamics and thermodynamic scenario are significant. The main findings of the current work are that the dimensionless velocity of the fluid increases as the gravity factor Rg decreases. The prominent change in the phase angle of current density αm and heat flux αt is examined for each value of the buoyancy parameter at both α=π/6 and π angles. The transitory skin friction and heat transfer rate shows a prominent magnitude of oscillation at both α=π/6 and π/2 positions, but current density increases with a higher magnitude of oscillation.
A Novel Discrete Differential Evolution with Varying Variables for the Deficiency Number of Mahjong Hand
Authors: Yan Xueqing , Li Yongming
Published: May 2023

The deficiency number of one hand, i.e., the number of tiles needed to change in order to win, is an important factor in the game Mahjong, and plays a significant role in the development of artificial intelligence (AI) for Mahjong. However, it is often difficult to compute due to the large amount of possible combinations of tiles. In this paper, a novel discrete differential evolution (DE) algorithm is presented to calculate the deficiency number of the tiles. In detail, to decrease the difficulty of computing the deficiency number, some pretreatment mechanisms are first put forward to convert it into a simple combinatorial optimization problem with varying variables by changing its search space. Subsequently, by means of the superior framework of DE, a novel discrete DE algorithm is specially developed for the simplified problem through devising proper initialization, a mapping solution method, a repairing solution technique, a fitness evaluation approach, and mutation and crossover operations. Finally, several experiments are designed and conducted to evaluate the performance of the proposed algorithm by comparing it with the tree search algorithm and three other kinds of metaheuristic methods on a large number of various test cases. Experimental results indicate that the proposed algorithm is efficient and promising.
The Development of a Data-Based Leakage Pinpoint Detection Technique for Water Distribution Systems
Authors: Kim Ryul , Choi Young Hwan
Published: May 2023

Leakage is one of the abnormal conditions in water distribution systems (WDSs). Real-time monitoring can be used to prevent or recover quickly from leakage. However, this is not enough: for improved leakage detection, a status diagnosis of the WDS must be performed together with this real-time monitoring, and numerous studies have been conducted on this. Furthermore, the existing proposed methodology only provides optimal sensor location and fast recognition. This paper proposes a technique that can quantitatively evaluate the volume of leakage along with leakage detection using deep learning technology. The hydraulic data (e.g., pressure, velocity, and flow) from the calibrated hydraulic model were used as training data and deep learning techniques were applied to conduct a simultaneous detection of leakage volume and location. We examined various scenarios regarding leakage volume and location for the data configuration of a simulated leakage accident. Furthermore, for optimal leakage detection performance, the detection performance according to the size of the network, the meter types of meters, the number of meters, and the locations of the meters were analyzed. This study is expected to be helpful in various aspects such as recovery and restoration decision making after leakage, because it simultaneously identifies the amount and location of the leakage.
CDE’ Inequality on Graphs with Unbounded Laplacian
Authors: Hong Desheng , Gong Chao
Published: May 2023

In this paper, we derive the gradient estimates of semigroups in terms of the modified curvature-dimension inequality CDE′ for unbounded Laplacians on complete graphs with non-degenerate measures.
Algorithms to Estimate the Ductile to Brittle Transition Temperature, Upper Shelf Energy, and Their Uncertainties for Steel Using Charpy V-Notch Shear Area and Absorbed Energy Data
Authors: Switzner Nathaniel T. , Anderson Joel , Ahmed Lanya Ali , Rosenfeld Michael , Veloo Peter
Published: May 2023

Toughness and the transition from ductile to brittle behavior are long-standing concerns for applications of ferritic steel such as line-pipe. Three algorithms have been developed to fit a hyperbolic tangent curve to any Charpy V-notch dataset and estimate the uncertainty for (1) the 85% shear appearance area transition temperature and (2) the upper shelf absorbed energy. To fit the hyperbolic tangent curve to the data the (I) first algorithm relied on iterative estimation of four-parameters; (II) the second algorithm on two parameters (after simplification based on physical assumptions); and (III) the third algorithm on only one parameter (after further simplification). The algorithms were written using the open-source programing language, R. The minimum input requirements for the algorithm are experimental data for shear appearance area and absorbed energy from at least four temperatures for the four-parameter algorithm, two temperatures for the two-parameter algorithm, and one temperature for the one-parameter algorithm. The test temperatures and quantity of tests at each temperature can vary. The algorithms are described in detail and demonstrated using a data set of 12 Charpy test results (shear area and absorbed energy) from one API-5L grade X52 pipe with 4.5 mm thick Charpy bars. A future paper will test and compare the algorithms using a wide variety of Charpy V-notch data sets to clarify their applicability and possible limitations.
Comparative Study of Protection Efficiency of C-Steel Using Polystyrene Clay Nanocomposite Coating Prepared from Commercial Indian Clay and Local Khulays Clay
Authors: Howyan Nashwa A. , Al Juhaiman Layla A. , Mekhamer Waffa K. , Altilasi Hissah H.
Published: May 2023

This work aimed to compare the coating protection efficiency of C-steel using two kinds of clay: a local Khulays clay (RCKh) from Saudi Arabia and a commercial clay (CCIn) from India. Clay-based polymer nanocomposites have a unique layered structure, rich intercalation chemistry, and availability at low cost. They are promising reinforcements for polymers. The raw clay for both clay types was washed before being treated with NaCl to produce sodium clay (NaC). The cationic surfactant cetylpyridinium chloride (CPC) was then used to convert the NaC into the organoclay (OC) form. Polystyrene/organoclay nanocomposites (PCNs) were prepared by combining different concentrations of organoclay (1%, 3%, and 5% OC) in toluene solvent and polystyrene (PS) as the matrix. To ensure the success of the PCN modification process, the organoclay and PCN films were characterized using a variety of techniques, including Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), and transmission electron microscopy (TEM). The shifts in the FT-IR spectra after the CPC treatment of NaC confirmed the presence of CPC in the organoclay samples and the presence of OC in the PCNs. The exfoliated structure was obtained from the XRD spectrum for low clay loading (1–3% PCN), while the intercalated structure was the dominant form for the 5% PCN. The XRD results were confirmed by TEM images. To calculate the coating efficiency of the PCNs, various electrochemical methods were used. The electrochemical measurements included electrochemical impedance spectroscopy (EIS), the electrochemical frequency modulation (EFM) method, and Tafel plots. The PCN with a concentration of 1 wt.% OC has a fully exfoliated structure and higher coating efficiency than the PCNs with partially exfoliated structures (3 wt.% and 5 wt.%). It was found from the Tafel plots that commercial Indian clay has better corrosion protection (81.4%) than local Khulays clay (60.2%). A comparison with other studies using current density values shows that our results are superior to those of many studies.
160 GHz D-Band Low-Noise Amplifier and Power Amplifier for Radar-Based Contactless Vital-Signs-Monitoring Systems
Authors: Mustapha Ademola Akeem , Sanduleanu Mihai
Published: May 2023

This paper presents a 160 GHz, D-band, low-noise amplifier (LNA) and a D-band power amplifier (PA) implemented in the Global Foundries 22 nm CMOS FDSOI. The two designs are used for the contactless monitoring of vital signs in the D-band. The LNA is based on multiple stages of a cascode amplifier topology with a common source topology adopted as the input and output stages. The input stage of the LNA is designed for simultaneous input and output matching, while the inter-stage-matching networks are designed for maximizing the voltage swing. The LNA achieved a maximum gain of 17 dB at 163 GHz. The input return loss was quite poor in the 157–166 GHz frequency band. The −3 dB gain bandwidth corresponded to 157–166 GHz. The measured noise figure was between 7.6 dB and 8 dB within the −3 dB gain bandwidth. The power amplifier achieved an output 1 dB compression point of 6.8 dBm at 159.75 GHz. The measured power consumptions of the LNA and the PA were 28.8 mW and 10.8 mW, respectively.
Extraction, Purification, Structural Characteristics, Biological Activities, and Applications of the Polysaccharides from Zingiber officinale Roscoe. (Ginger): A Review
Authors: Hu Wenjing , Yu Aiqi , Wang Shuang , Bai Qianxiang , Tang Haipeng , Yang Bingyou , Wang Meng , Kuang Haixue
Published: May 2023

Zingiber officinale Roscoe. (ginger) is a widely distributed plant with a long history of cultivation and consumption. Ginger can be used as a spice, condiment, food, nutrition, and as an herb. Significantly, the polysaccharides extracted from ginger show surprising and satisfactory biological activity, which explains the various benefits of ginger on human health, including anti-influenza, anti-colitis, anti-tussive, anti-oxidant, anti-tumor effects. Here, we systematically review the major studies on the extraction and purification of polysaccharides from ginger in recent years, the characterization of their chemical structure, biological activity, and structure–activity relationships, and the applications of ginger polysaccharides in different fields. This article will update and deepen the understanding of ginger polysaccharide and provide a theoretical basis for its further research and application in human health and product development.
Household Splitting Process and Food Security in Malawi
Authors: Sassi Maria
Published: May 2023

Despite the frequent changes in household composition in Sub-Saharan Africa, the literature on the household division process is sparse, with no evidence of its effect on food security. This paper addresses the topic in Malawi, where the fission process is evident and malnutrition is a severe problem. Using the Integrated Household Panel Dataset, this study applies the difference-in-difference model with the propensity score matching technique to compare matched groups of households that did and did not split between 2010 and 2013. The results suggest that coping strategies adopted by poor households and life course events determine household fission in Malawi, a process that benefits household food security in the short term. On average, the food consumption score is 3.74 units higher among households that split between 2010 and 2013 compared to the matched households that did not. However, the household division might have long-run adverse effects on food insecurity, especially for poor households due to the adoption of coping strategies that might compromise their human capital and income-generating activities. Therefore, this process warrants attention for the more accurate understanding, design, and evaluation of food security interventions.
Exploring the Relationship between Disordered Sleep and Mood in Male Anorexia Nervosa: An Actigraphy Study
Authors: Lim Mengyu , Kou Ruoxin , Esposito Gianluca , Jawed Aisha , Dimitriou Dagmara , Mangar Stephen A.
Published: May 2023

Eating disorders (EDs), including anorexia nervosa (AN), are severe psychological disorders that affect individuals’ eating behaviours and body perception. Previous research has shown that people with EDs often report poorer sleep. Some literature has suggested that it is mood dysregulation that mediates the link between EDs and sleep. However, the majority of previous studies only focused on females, while male ED patients have been overlooked. Therefore, the present study aimed to investigate the relationships between EDs, mood, and sleep among male ED patients. Using a mixture of actigraphy recordings and self-reported questionnaires, the current study analysed a total 33 adult male participants diagnosed with AN. The participants first wore an actigraphy device for seven continuous days, following which their ED severity and mood were assessed by the Eating Disorder Examination Questionnaire (EDE-Q) and Depression Anxiety Stress Scale (DASS), respectively. The descriptive actigraphy results suggested that, similar to females, males with AN also showed disturbed sleep, including insomnia, sleep fragmentation, low sleep efficiency, and increased napping sessions. However, when ED severity was correlated against actigraphy data and mood, no significant relationships were found between them. Thus, it was suggested that future studies may investigate discrete ED symptoms instead of global ED severity interacting with sleep and mood. Overall, this study represents an initial step in the investigation of EDs and sleep and mood dysregulation among an under-represented sample.
Development of Bioluminescent Virulent Aeromonas hydrophila for Understanding Pathogenicity
Authors: Ozdemir Eda , Abdelhamed Hossam , Ozdemir Ozan , Lawrence Mark , Karsi Attila
Published: May 2023

Virulent Aeromonas hydrophila (vAh) strains that cause motile Aeromonas septicemia (MAS) in farmed channel catfish (Ictalurus punctatus) have been an important problem for more than a decade. However, the routes of infection of vAh in catfish are not well understood. Therefore, it is critical to study the pathogenicity of vAh in catfish. To this goal, a new bioluminescence expression plasmid (pAKgfplux3) with the chloramphenicol acetyltransferase (cat) gene was constructed and mobilized into vAh strain ML09-119, yielding bioluminescent vAh (BvAh). After determining optimal chloramphenicol concentration, plasmid stability, bacteria number–bioluminescence relationship, and growth kinetics, the catfish were challenged with BvAh, and bioluminescent imaging (BLI) was conducted. Results showed that 5 to 10 µg/mL chloramphenicol was suitable for stable bioluminescence expression in vAh, with some growth reduction. In the absence of chloramphenicol, vAh could not maintain pAKgfplux3 stably, with the half-life being 16 h. Intraperitoneal injection, immersion, and modified immersion (adipose fin clipping) challenges of catfish with BvAh and BLI showed that MAS progressed faster in the injection group, followed by the modified immersion and immersion groups. BvAh was detected around the anterior mouth, barbels, fin bases, fin epithelia, injured skin areas, and gills after experimental challenges. BLI revealed that skin breaks and gills are potential attachment and entry portals for vAh. Once vAh breaches the skin or epithelial surfaces, it can cause a systemic infection rapidly, spreading to all internal organs. To our best knowledge, this is the first study that reports the development of a bioluminescent vAh and provides visual evidence for catfish–vAh interactions. Findings are expected to provide a better understanding of vAh pathogenicity in catfish.
Multigene Phylogeny and Pathogenicity Trials Revealed Alternaria alternata as the Causal Agent of Black Spot Disease and Seedling Wilt of Pecan (Carya illinoinensis) in South Africa
Authors: Achilonu Conrad Chibunna , Marais Gert Johannes , Ghosh Soumya , Gryzenhout Marieka
Published: May 2023

The pecan (Carya illinoinensis) industry in South Africa is growing rapidly, and it is becoming increasingly crucial to understand the risks posed to pecans by fungal pathogens. Black spots on leaves, shoots, and nuts in shucks caused by Alternaria species have been observed since 2014 in the Hartswater region of the Northern Cape Province of South Africa. Species of Alternaria include some of the most ubiquitous plant pathogens on earth. The aim of this study was to use molecular techniques to identify the causative agents of Alternaria black spot and seedling wilt isolated from major South African pecan-production areas. Symptomatic and non-symptomatic pecan plant organs (leaves, shoots, and nuts-in-shucks) were collected from pecan orchards, representing the six major production regions in South Africa. Thirty Alternaria isolates were retrieved from the sampled tissues using Potato Dextrose Agar (PDA) culture media and molecular identification was conducted. The phylogeny of multi-locus DNA sequences of Gapdh, Rpb2, Tef1, and Alt a 1 genes revealed that the isolates were all members of Alternaria alternata sensu stricto, forming part of the Alternaria alternata species complex. The virulence of six A. alternata isolates were tested on detached nuts of Wichita and Ukulinga cultivars, respectively, as well as detached leaves of Wichita. The A. alternata isolates were also evaluated for their ability to cause seedling wilt in Wichita. The results differed significantly between wounded and unwounded nuts of both cultivars, but not between the cultivars. Similarly, the disease lesions on the wounded detached leaves were significantly different in size from the unwounded leaves. The seedling tests confirmed that A. alternata is pathogenic and that A. alternata causes black spot disease and seedling wilt of pecans. This study is one of the first documentations of Alternaria black spot disease of pecan trees and its widespread occurrence in South Africa.
Detection of HEV RNA Using One-Step Real-Time RT-PCR in Farrow-to-Finish Pig Farms in Bulgaria
Authors: Krumova-Valcheva Gergana Lyubomirova , Di Bartolo Ilaria , Smith Richard Piers , Gyurova Eva , Mateva Gergana , Milanov Mihail , Dimitrova Albena , Burow Elke , Daskalov Hristo
Published: May 2023

(1) Background: HEV is a zoonotic, foodborne pathogen. It is spread worldwide and represents a public health risk. The aim of this study was to evaluate the presence of HEV RNA in farrow-to-finish pig farms in different regions of Bulgaria; (2) Methods: Isolation of HEV RNA from pooled samples of feces was performed using a QIAamp® Viral RNA Mini Kit followed by HEV RNA detection using a single-step real-time RT-PCR with primers and probes targeting the ORF 3 HEV genome; (3) Results: HEV RNA was detected in 12 out of 32 tested farms in Bulgaria (37.5%). The overall percentage of HEV-positive pooled fecal samples was 10.8% (68 of 630 samples). HEV was detected mostly in pooled fecal samples from finisher pigs (66/320, 20.6%) and sporadically from dry sows (1/62, 1.6%) and gilts (1/248, 0.4%); (4) Conclusions: Our results confirm that HEV circulates in farrow-to-finish pig farms in Bulgaria. In our study, we found HEV RNA in pooled fecal samples from fattening pigs (4–6-months age), shortly before their transport to the slaughterhouse indicating a potential risk to public health. The possible circulation of HEV throughout pork production requires monitoring and containment measures.
Intraperitoneally Administered Vancomycin in Patients with Peritoneal Dialysis-Associated Peritonitis: Population Pharmacokinetics and Dosing Implications
Authors: Hartinger Jan Miroslav , Michaličková Danica , Dvořáčková Eliška , Hronová Karolína , Krekels Elke H. J. , Szonowská Barbora , Bednářová Vladimíra , Benáková Hana , Kroneislová Gabriela , Závora Jan , Tesař Vladimír , Slanař Ondřej
Published: May 2023

Peritonitis is a limiting complication of peritoneal dialysis, which is treated by intraperitoneal administration of antibiotics. Various dosing strategies are recommended for intraperitoneally administered vancomycin, which leads to large differences in intraperitoneal vancomycin exposure. Based on data from therapeutic drug monitoring, we developed the first-ever population pharmacokinetic model for intraperitoneally administered vancomycin to evaluate intraperitoneal and plasma exposure after dosing schedules recommended by the International Society for Peritoneal Dialysis. According to our model, currently recommended dosing schedules lead to possible underdosing of a large proportion of patients. To prevent this, we suggest avoiding intermittent intraperitoneal vancomycin administration, and for the continuous dosing regimen, we suggest a loading dose of 20 mg/kg followed by maintenance doses of 50 mg/L in each dwell to improve the intraperitoneal exposure. Vancomycin plasma level measurement on the fifth day of treatment with subsequent dose adjustment would prevent it from reaching toxic levels in the few patients who are susceptible to overdose.
Synergistic Activity of Thymol with Commercial Antibiotics against Critical and High WHO Priority Pathogenic Bacteria
Authors: Gan Cristina , Langa Elisa , Valenzuela Antonio , Ballestero Diego , Pino-Otín M. Rosa
Published: May 2023

The use of synergistic combinations between natural compounds and commercial antibiotics may be a good strategy to fight against microbial resistance, with fewer side effects on human, animal and environmental, health. The antimicrobial capacity of four compounds of plant origin (thymol and gallic, salicylic and gentisic acids) was analysed against 14 pathogenic bacteria. Thymol showed the best antimicrobial activity, with MICs ranging from 125 µg/mL (for Acinetobacter baumannii, Pasteurella aerogenes, and Salmonella typhimurium) to 250 µg/mL (for Bacillus subtilis, Klebsiella aerogenes, Klebsiella pneumoniae, Serratia marcescens, Staphylococcus aureus, and Streptococcus agalactiae). Combinations of thymol with eight widely used antibiotics were studied to identify combinations with synergistic effects. Thymol showed synergistic activity with chloramphenicol against A. baumannii (critical priority by the WHO), with streptomycin and gentamicin against Staphylococcus aureus (high priority by the WHO), and with streptomycin against Streptococcus agalactiae, decreasing the MICs of these antibiotics by 75% to 87.5%. The kinetics of these synergies indicated that thymol alone at the synergy concentration had almost no effect on the maximum achievable population density and very little effect on the growth rate. However, in combination with antibiotics at the same concentration, it completely inhibited growth, confirming its role in facilitating the action of the antibiotic. The time–kill curves indicated that all the combinations with synergistic effects were mainly bactericidal.
A Review on Remediation of Iron Ore Mine Tailings via Organic Amendments Coupled with Phytoremediation
Authors: Sarathchandra Sajeevee S. , Rengel Zed , Solaiman Zakaria M.
Published: May 2023

Mining operations degrade natural ecosystems by generating a large quantity of mine tailings. Mine tailings remain in dams/open ponds without further treatment after valuable metals such as iron ore have been extracted. Therefore, rehabilitation of tailings to mitigate the negative environmental impacts is of the utmost necessity. This review compares existing physical, chemical and amendment-assisted phytoremediation methods in the rehabilitation of mine tailings from the perspective of cost, reliability and durability. After review and discussion, it is concluded that amendment-assisted phytoremediation has received comparatively great attention; however, the selection of an appropriate phytoremediator is the critical step in the process. Moreover, the efficiency of phytoremediation is solely dependent on the amendment type and rate. Further, the application of advanced plant improvement technologies, such as genetically engineered plants produced for this purpose, would be an alternative solution. Further research is needed to determine the suitability of this method for the particular environment.
Rheological Properties of Small-Molecular Liquids at High Shear Strain Rates
Authors: Li Wenhui , Kadupitiya JCS , Jadhao Vikram
Published: May 2023

Molecular-scale understanding of rheological properties of small-molecular liquids and polymers is critical to optimizing their performance in practical applications such as lubrication and hydraulic fracking. We combine nonequilibrium molecular dynamics simulations with two unsupervised machine learning methods: principal component analysis (PCA) and t-distributed stochastic neighbor embedding (t-SNE), to extract the correlation between the rheological properties and molecular structure of squalane sheared at high strain rates (106–1010s−1) for which substantial shear thinning is observed under pressures P∈0.1–955 MPa at 293 K. Intramolecular atom pair orientation tensors of 435×6 dimensions and the intermolecular atom pair orientation tensors of 61×6 dimensions are reduced and visualized using PCA and t-SNE to assess the changes in the orientation order during the shear thinning of squalane. Dimension reduction of intramolecular orientation tensors at low pressures P=0.1,100 MPa reveals a strong correlation between changes in strain rate and the orientation of the side-backbone atom pairs, end-backbone atom pairs, short backbone-backbone atom pairs, and long backbone-backbone atom pairs associated with a squalane molecule. At high pressures P≥400 MPa, the orientation tensors are better classified by these different pair types rather than strain rate, signaling an overall limited evolution of intramolecular orientation with changes in strain rate. Dimension reduction also finds no clear evidence of the link between shear thinning at high pressures and changes in the intermolecular orientation. The alignment of squalane molecules is found to be saturated over the entire range of rates during which squalane exhibits substantial shear thinning at high pressures.
2-Methoxy-4-Vinylphenol as a Biobased Monomer Precursor for Thermoplastics and Thermoset Polymers
Authors: Alexakis Alexandros E. , Ayyachi Thayanithi , Mousa Maryam , Olsén Peter , Malmström Eva
Published: May 2023

To address the increasing demand for biobased materials, lignin-derived ferulic acid (FA) is a promising candidate. In this study, an FA-derived styrene-like monomer, referred to as 2-methoxy-4-vinylphenol (MVP), was used as the platform to prepare functional monomers for radical polymerizations. Hydrophobic biobased monomers derived from MVP were polymerized via solution and emulsion polymerization resulting in homo- and copolymers with a wide range of thermal properties, thus showcasing their potential in thermoplastic applications. Moreover, divinylbenzene (DVB)-like monomers were prepared from MVP by varying the aliphatic chain length between the MVP units. These biobased monomers were thermally crosslinked with thiol-bearing reagents to produce thermosets with different crosslinking densities in order to demonstrate their thermosetting applications. The results of this study expand the scope of MVP-derived monomers that can be used in free-radical polymerizations toward the preparation of new biobased and functional materials from lignin.
Security-Guaranteed PID Control for Discrete-Time Systems Subject to Periodic Dos Attacks
Authors: Hou Nan , Zhang Duo , Yang Fan , Li Weijian , Sui Yang
Published: May 2023

This paper is concerned with the observer-based H∞ proportional-integral-derivative (PID) control issue for discrete-time systems using event-triggered mechanism subject to periodic random denial of service (DoS) jamming attacks and infinitely distributed delays. In order to characterize the occurrence of periodic random DoS jamming attacks in the network channel between controller and actuator, the Kronecker delta function is used to represent the periodic switching between the sleeping period and attack period, and a Bernoulli-distributed random variable is utilized to reflect the probabilistic occurrence of DoS attacks. Infinitely distributed delay is involved to reflect actual state lag. The relative event-triggering mechanism is employed to reduce unnecessary information transmission and save communication energy in the network channel between sensor and observer. An observer-based PID controller is constructed for the regulation of the system to achieve an appropriate working effect. The aim of this paper is to design a security-guaranteed PID controller for delayed systems such that both the exponential mean-square stability and the H∞ performance are satisfied. Using the Lyapunov stability theory, stochastic analysis method and matrix inequality technique, a sufficient condition is put forward that ensures the existence of the required observer and PID controller. Gain parameters of the observer and the PID controller are computed by solving a certain matrix inequality. A simulation is carried out to verify the effectiveness of the developed observer-based H∞ PID control method. The obtained H∞ noise rejection level is below 0.85, the average event-based release interval is 13, the absolute values of the maximum estimation error of two elements in the system state are 1.434 and 0.371 using the observer, and two elements of the system state converge to 0.238 and −0.054 at the 41th time step with two elements of the control output being 0.031 and 0.087.
Study on Flow Characteristics of Hydraulic Suction of Seabed Ore Particles
Authors: Xia Qiu , Jia Hao , Sun Jiuchun , Xi Xiaoguang , Cui Jingyu
Published: May 2023

Efficient and environmentally friendly ore collecting operation requires that the ore collecting head can provide just enough suction to start the ore particles in different working conditions. In this work, computational fluid dynamics and discrete element method (CFD-DEM) is used to simulate the hydraulic suction process of ore particles. After analyzing the pressure and velocity characteristics of the flow field, the effects of different suction velocities on the lateral displacement offset, drag coefficient Cd and Reynolds number Rep of particles are studied. It is determined that the lifting force is caused by the different flow velocities of the upper and lower flow fields; particle start-up time and the lateral offset are inversely proportional to suction speed. When h/d ≥ 2.25, the vertical force on particles is no longer affected by h/d. When S/d = 2.5, FZ decreases to 0 N; when h/d increases from 1.5 to 1.75, FZ decreases by nearly half. Three empirical equations for FZ represented by D/d, h/d, and S/d are obtained. After integrating the above three equations, the functional relationship of FZ with D/d, h/d and S/d is finally obtained within a certain range. The errors of the equations are within 6%. The particle stress characteristics obtained in this paper can be applied to the establishment of ore collecting performance prediction model and provide data support for the research and development of intelligent ore collecting equipment.