bluuebunny/crossref_metadata_2025 huggingface dataset:
Robust Statistic Estimation of Constrained Optimal Control Problems of Pollution Accumulation (Part I)
Authors: Escobedo-Trujillo Beatris Adriana , López-Barrientos José Daniel , Higuera-Chan Carmen Geraldi , Alaffita-Hernández Francisco Alejandro
Published: February 2023

In this paper, we study a constrained optimal control on pollution accumulation where the dynamic system was governed by a diffusion process that depends on unknown parameters, which need to be estimated. As the true values are unknown, we intended to determine (adaptive) policies that maximize a discounted reward criterion with constraints, that is, we used Lagrange multipliers to find optimal (adaptive) policies for the unconstrained version of the optimal control problem. In the present context, the dynamic system evolves as a diffusion process, and the cost function is to be minimized by another function (typically a constant), which plays the role of a constraint in the control model. We offer solutions to this problem using standard dynamic programming tools under the constrained discounted payoff criterion on an infinite horizon and the so-called principle of estimation and control. We used maximum likelihood estimators by means of a minimum least square error approximation in a pollution accumulation model to illustrate our results. One of the advantages of our approach compared to others is the intuition behind it: find optimal policies for an estimated version of the problem and let this estimation tend toward the real version of the problem. However, most risk analysts will not be as used to our methods as they are to, for instance, the model predictive control, MATLAB’s robust control toolbox, or the polynomial chaos expansion method, which have been used in the literature to address similar issues.
Improved Properties of Positive Solutions of Higher Order Differential Equations and Their Applications in Oscillation Theory
Authors: Almarri Barakah , Moaaz Osama
Published: February 2023

In this article, we present new criteria for testing the oscillation of solutions of higher-order neutral delay differential equation. By deriving new monotonic properties of a class of the positive solutions of the studied equation, we establish better criteria for oscillation. Furthermore, we improve these properties by giving them an iterative character, allowing us to apply the criteria more than once. The results obtained in this paper are characterized by the fact that they do not require the existence of unknown functions and do not need the commutation condition to composition of the delay functions, which are necessary conditions for the previous related results.
Some Applications of Analytic Functions Associated with q-Fractional Operator
Authors: Khan Nazar , Khan Shahid , Xin Qin , Tchier Fairouz , Malik Sarfraz Nawaz , Javed Umer
Published: February 2023

This paper introduces a new fractional operator by using the concepts of fractional q-calculus and q-Mittag-Leffler functions. With this fractional operator, Janowski functions are generalized and studied regarding their certain geometric characteristics. It also establishes the solution of the complex Briot–Bouquet differential equation by using the newly defined operator.
On Local Time for Telegraph Processes
Authors: Ratanov Nikita , Turov Mikhail
Published: February 2023

The article consists of an introduction into the theory of passage times associated with telegraph processes. Local time for the telegraph process is defined and analysed. We provide some limited results for telegraphic local times.
Optimal Orientation of Solar Panels for Multi-Apartment Buildings
Authors: Yoon Sungha , Park Jintae , Lee Chaeyoung , Kim Sangkwon , Choi Yongho , Kwak Soobin , Kim Hyundong , Kim Junseok
Published: February 2023

In this paper, we present a mathematical algorithm for the optimal orientation of solar panels for multi-apartment buildings. Currently, photovoltaic power generation has increasingly become an effective method. It has the advantage of not causing environmental pollution; however, it has the disadvantage of relatively low power generation efficiency. To increase the power efficiency of the panel, one can consider a rotation. However, if there is a limitation to the rotation angle of the solar panel, especially in multi-apartment buildings, it is desirable to install the panel at the optimal angle under given constraints. Therefore, we present a simple and practical method to evaluate the optimal installation angle of the panel. Using the proposed method, it is easy to find an optimal installation angle to achieve the best power generation efficiency based on the latitude and azimuth angles. To demonstrate the effectiveness of the proposed algorithm, several numerical simulation results are provided.
Optimization of MHD Flow of Radiative Micropolar Nanofluid in a Channel by RSM: Sensitivity Analysis
Authors: Alahmadi Reham A. , Raza Jawad , Mushtaq Tahir , Abdelmohsen Shaimaa A. M. , R. Gorji Mohammad , Hassan Ahmed M.
Published: February 2023

These days, heat transfer plays a significant role in the fields of engineering and energy, particularly in the biological sciences. Ordinary fluid is inadequate to transfer heat in an efficient manner, therefore, several models were considered for the betterment of heat transfer. One of the most prominent models is a single-phase nanofluid model. The present study is devoted to solving the problem of micropolar fluid with a single-phase model in a channel numerically. The governing partial differential equations (PDEs) are converted into nonlinear ordinary differential equations (ODEs) by introducing similarity transformation and then solved numerically by the finite difference method. Response surface methodology (RSM) together with sensitivity analysis are implemented for the optimization analysis. The study reveals that sensitivity of the skin friction coefficient (Cfx) to the Reynolds number (R) and magnetic parameter (M) is positive (directly proportional) and negative (inversely proportional) for the micropolar parameter.
Detection of Actuator Enablement Attacks by Petri Nets in Supervisory Control Systems
Authors: Yu Zhenhua , Duan Xudong , Cong Xuya , Li Xiangning , Zheng Li
Published: February 2023

The feedback control system with network-connected components is vulnerable to cyberattacks. We study a problem of attack detection in supervisory control of discrete-event systems. The scenario of a system subjected to actuator enablement attacks is considered in this article. We also consider that some unsafe places that should be protected from an attacker exist in the system, and some controllable events that are disabled by a supervisor might be re-enabled by an attacker. This article proposes a defense strategy to detect actuator enablement attacks and disable all controllable events after detecting an attack. We design algorithmic procedures to determine whether the system can be protected against damage caused by actuator enablement attacks, where the damage is predefined as a set of “unsafe” places. In this way, the system property is called “AE-safe controllability”. The safe controllability can be verified by using a basis diagnoser or a basis verifier. Finally, we explain the approach with a cargo system example.
Analytical and Numerical Model of Sloshing in a Rectangular Tank Subjected to a Braking
Authors: Balaş Oana-Maria , Doicin Cristian Vasile , Cipu Elena Corina
Published: February 2023

This paper examines the movement of waves that occur in a fuel tank—both with and without a wave breaker—when a car is travelling at a constant speed and then suddenly brakes. This phenomenon is known as slosh noise, and the paper presents an analysis of the movement of free surfaces in relation to the level of noise generated. The paper focuses on mathematical models of the fluid flow for both tanks—one without any technical solutions for breaking waves, and the other with a solution for breaking waves. The model is constructed based on a set of initial hypotheses about the fluid flow within the tank, by developing the speed potential in a series of fundamental solutions and considering the main variables that affect the phenomenon of sloshing, such as the depth of the liquid, the tank’s geometry, and the frequency and amplitude of the initial external force acting on the tank. The analysis of free surface movement is used to find the correlation with the sound generated in the tank. Nonlinearities that arise from the sudden braking are also modelled and numerically studied using MATLAB software. Following the mathematical model, a technical wave-breaking solution was implemented and tested, and it was shown that the amplitude of the movement of the free surface is reduced by half. Further research on the correspondence between the free surface movement based on the behaviour of potential energies in the two cases may be developed.
Analytical Methods in Wave Scattering and Diffraction Volume I
Authors: Tsitsas Nikolaos L.
Published: February 2023

Boundary value problems (BVPs) pertaining to scattering and radiation by devices that support novel wave phenomena are of primary importance in applied and computational mathematics, computational physics and engineering [...]
Generalized Thermoelastic Interaction in Orthotropic Media under Variable Thermal Conductivity Using the Finite Element Method
Authors: Hobiny Aatef , Abbas Ibrahim
Published: February 2023

This article addresses a thermoelastic problem under varying thermal conductivity with and without Kirchhoff’s transforms. The temperature increment, displacement, and thermal stresses in an orthotropic material with spherical cavities are studied. The inner surface of the hole is constrained and heated by thermal shock. The numerical solutions are derived using the finite element technique in the setting of the generalized thermoelasticity model with one thermal delay time. The thermal conductivity of the material is supposed to be temperature-dependent without Kirchhoff’s transformation. Due to the difficulty of nonlinear formulations, the finite element approach is used to solve the problem without using Kirchhoff’s transformation. The solution is determined using the Laplace transform and the eigenvalues technique when employing Kirchhoff’s transformation in a linear example. Variable thermal conductivity is addressed and compared with and without Kirchhoff’s transformation. The numerical result for the investigated fields is graphically represented. According to the numerical analysis results, the varying thermal conductivity provides a limited speed for the propagations of both mechanical and thermal waves.
Disordered Eating Behaviors and Insulin Restriction in Saudi Adolescents and Young Adults with Type 1 Diabetes
Authors: Yafei Saeed , Hummadi Abdulrahman , Badedi Mohammed , Darraj Hussain , Khawaji Abdullah , Alzughbi Turki , Abutaleb Raed , Alhagawy Ali Jaber , Alnami Awaji , Kudam Bayan , Bahsan Fatma , Kariri Maryam , Adawi Morghama , Daghriri Mohammed , Hassan Rania , Soeid Mohammed , Alzughbi Nouf
Published: February 2023

Background and Objectives: The prevalence of disordered eating behaviors (DEBs) in type 1 diabetes (T1D) has been studied globally; however, data from Saudi Arabia and Arab-speaking countries are scarce. This study aimed to measure the prevalence of DEBs and associated clinical characteristics in adolescents and young adults with T1D, and the impact of DEBs on glycemic parameters. Materials and Methods: A total of 265 adolescents and young adults with T1D (aged 12–25 years) were recruited randomly from the registry at the Jazan Endocrinology and Diabetes Center, Saudi Arabia. Participants completed the Diabetes Eating Problem Survey–Revised (DEPS-R) questionnaire. Other measures included hemoglobin A1c (HbA1c) in addition to sociodemographic, anthropometric, and clinical data. Results: The prevalence of DEBs among T1D was 27.2%. Females (32.5%) had a higher proportion of DEBs than males (18.6%) (p = 0.01). About 27% of the participants reported insulin restriction. A history of hospital admission in the previous 6 months due to DKA and frequent hypoglycemia was more frequently reported in T1D participants with DEBs compared to those without (p = 0.03). Participants with DEBs had higher HbA1c and higher BMI compared to those without DEBs. Conclusions: Adolescents and young adults with T1D with disordered eating and insulin restriction have higher glycated hemoglobin, and are at higher risk of DKA. Routine screening for DEBs should be an essential element in diabetes care, especially among highly vulnerable groups.
Correlations between Gut Microbial Composition, Pathophysiological and Surgical Aspects in Endometriosis: A Review of the Literature
Authors: Iavarone Irene , Greco Pier Francesco , La Verde Marco , Morlando Maddalena , Torella Marco , de Franciscis Pasquale , Ronsini Carlo
Published: February 2023

Background and Objectives: Endometriosis is an estrogen-dependent, inflammatory, gynecological disorder represented by the migration of endometrial tissue outside the uterus. It can manifest through gynecological and gastrointestinal (GI) signs. Given the hormonal imbalances in endometriosis and the effect of microbiota on immune dysfunction, it has been thought that the human microbiome may play a role in its pathogenesis, acting differently before and after laparotomy. The aim of this review is to establish whether there is an interaction between endometriosis and gut microbial composition. Materials and Methods: We aimed to review available literature by systematically searching five databases: PubMed, EMBASE, Scopus, Cochrane Library, and ScienceDirect. We included records describing gut microbiota in the context of endometriosis—observing PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analysis) guidelines—to recognize the presence of disease by the expression of bacterial taxa—based on 16S ribosomal RNA gene sequencing analysis. Results: Among 10 studies selected, there were four review articles and six clinical trials. The latter identified significant differences at a genus level in increased Prevotella, Blautia, and Bifidobacterium and decreased Paraprevotella, Ruminococcus, and Lachnospira (p < 0.05). In patients undergoing abdominal hysterectomy, Proteobacteria phylum increased from 34.36% before surgery to 54.04% after surgery (p < 0.05). Conclusions: Although scientific literature reports different characterizations of intestinal microbiota in endometriotic patients, further evidence is needed to develop new diagnostic-therapeutic strategies, for example, administration with probiotics before surgery.
Bevacizumab Treatment for Metastatic Colorectal Cancer in Real-World Clinical Practice
Authors: Dinu Ioana Mihaela , Mihăilă Mariana , Diculescu Mircea Mihai , Croitoru Vlad Mihai , Turcu-Stiolica Adina , Bogdan Diana , Miron Monica Ionela , Lungulescu Cristian Virgil , Alexandrescu Sorin Tiberiu , Dumitrașcu Traian , Buică Florina , Luca Ioana Niculina , Lungulescu Cristina , Negulescu Madalina Cristina , Gramaticu Iulia Magdalena , Cazacu Irina Mihaela , Croitoru Adina Emilia
Published: February 2023

Background and Objectives: Colorectal cancer (CRC) is a leading cause of cancer-related mortality and morbidity worldwide. Bevacizumab was approved for the treatment of metastatic colorectal cancer (mCRC) based on favorable benefit-risk assessments from randomized controlled trials, but evidence on its use in the real-world setting is limited. The aim of the current study is to evaluate the outcomes and safety profile of bevacizumab in mCRC in a real-world setting in Romania. Patients and Methods: This was an observational, retrospective, multicentric, cohort study conducted in Romania that included patients with mCRC treated with bevacizumab as part of routine clinical practice. Study endpoints were progression-free survival, overall survival, adverse events, and patterns of bevacizumab use. Results: A total of 554 patients were included in the study between January 2008 and December 2018. A total of 392 patients (71%) received bevacizumab in the first line and 162 patients (29%) in the second line. Bevacizumab was mostly combined with a capecitabine/oxaliplatin chemotherapy regimen (31.6%). The median PFS for patients treated with bevacizumab was 8.4 months (interquartile range [IQR], 4.7–15.1 months) in the first line and 6.6 months (IQR, 3.8–12.3 months) in the second line. The median OS was 17.7 months (IQR, 9.3–30.6 months) in the first line and 13.5 months (IQR, 6.7–25.2 months) in the second line. Primary tumor resection was associated with a longer PFS and OS. The safety profile of bevacizumab combined with chemotherapy was similar to other observational studies in mCRC. Conclusions: The safety profile of bevacizumab was generally as expected. Although the PFS was generally similar to that reported in other studies, the OS was shorter, probably due to the less frequent use of bevacizumab after disease progression and the baseline patient characteristics. Patients with mCRC treated with bevacizumab who underwent resection of the primary tumor had a higher OS compared to patients with an unresected primary tumor.
Temperature-Sensitive Auditory Neuropathy: Report of a Novel Variant of OTOF Gene and Review of Current Literature
Authors: Forli Francesca , Capobianco Silvia , Berrettini Stefano , Bruschini Luca , Romano Silvia , Fogli Antonella , Bertini Veronica , Lazzerini Francesco
Published: February 2023

Background and objectives: Otoferlin is a multi-C2 domain protein implicated in neurotransmitter-containing vesicle release and replenishment of the cochlear inner hair cell (IHC) synapses. Mutations in the OTOF gene have been associated with two different clinical phenotypes: a prelingual severe-to-profound sensorineural hearing loss (ANSD-DFNB9); and the peculiar temperature-sensitive auditory neuropathy (TS-ANSD), characterized by a baseline mild-to-moderate hearing threshold that worsens to severe-to-profound when the body temperature rises that returns to a baseline a few hours after the temperature has fallen again. The latter clinical phenotype has been described only with a few OTOF variants with an autosomal recessive biallelic pattern of inheritance. Case report: A 7-year-old boy presented a picture compatible with TS-ANSD exacerbated by febrile states or physical exercise with mild-to-moderate hearing loss at low and medium frequencies and a decrease in speech discrimination that worsened with an unfavorable speech-to-noise ratio. Otoacoustic emissions (OAEs) were present whereas auditory brainstem responses (ABRs) evoked by a click or tone-burst were generally absent. No inner ear malformations were described from the CT scan or MRI. Next-generation sequencing (NGS) of the known deafness genes and multi-phasic bioinformatic analyses of the data detected in OTOF a c.2521G>A missense variant and the deletion of 7.4 Kb, which was confirmed by array-comparative genomic hybridization (array-CGH). The proband’s parents, who were asymptomatic, were tested by Sanger sequencing and the father presented the c.2521G>A missense variant. Conclusions: The picture presented by the patient was compatible with OTOF-induced TS-ANSD. OTOF has been generally associated with an autosomal recessive biallelic pattern of inheritance; in this clinical report, two pathogenic variants never previously associated with TS-ANSD were described.
Recent Progresses in Non-Dialysis Chronic Kidney Disease Patients with Hyperkalemia: Outcomes and Therapeutic Strategies
Authors: Tian Ruixue , Li Rongshan , Zhou Xiaoshuang
Published: February 2023

Chronic kidney disease (CKD) affects about 10% of the world’s population. Hyperkalemia is a life-threatening complication in patients with CKD, as it is associated with adverse cardiovascular and kidney outcomes. There are still many challenges and questions to address to improve the currently available therapeutic strategies to treat hyperkalemia, such as how to approach the emergency management of hyperkalemia. In recent years, in addition to novel oral potassium binders, great progress has been made in the application of novel kidney protective strategies, such as mineralocorticoid receptor antagonists and sodium–glucose cotransporter 2 inhibitors (SGLT2i) in hyperkalemia therapy. This review will discuss the recent advances from clinical trials in the effective management of hyperkalemia in non-dialysis CKD patients, enhancing the knowledge of physicians and internists concerning these newer agents and providing a helpful reference for clinical practice.
Incidence of Post-Operative Pain following a Single-Visit Pulpectomy in Primary Molars Employing Adaptive, Rotary, and Manual Instrumentation: A Randomized Clinical Trial
Authors: Thakur Bhagyashree , Bhardwaj Anuj , Wahjuningrum Dian Agustin , Luke Alexander Maniangat , Shetty Krishna Prasad , Pawar Ajinkya M. , Reda Rodolfo , Seracchiani Marco , Zanza Alessio , Testarelli Luca
Published: February 2023

Background and Objectives. To differentiate the intensity of postoperative pain after primary molar pulpectomy employing manual instrumentation versus two single-file systems with different kinetics (the XP-Endo shaper file with adaptive instrumentation vs. the Kedo-SG blue file with continuous rotation instrumentation). Materials and Methods. This three-arm, single-blind, randomized clinical trial included assessing 75 healthy children between 4 to 9 years who required pulpectomy for primary molars (mandibular first and second). The three groups each had an equal number of children. Children in Group 1 had their teeth instrumented with the XP-endo Shaper, children in Group 2 had their teeth instrumented with the Kedo-SG Blue file, and children in Group 3 had their teeth instrumented manually using K-files. The degree of postoperative pain was measured using a four-point pain scale at 6-, 12-, 24-, 48-, and 72-h following therapy. Each participant’s parent received five flashcards with four faces and a word characterizing each face. The data were analyzed using Kruskal–Wallis and chi-square tests. The level of significance was set to 5%. Results. During the follow-up period, there was a significant difference in postoperative pain intensity between the three groups. The XP-endo shaper was associated with considerably decreased post operative at the 6- and 12-h interval followed by Kedo-SG. The highest post-operative discomfort across the groups was related to the patients who underwent manual instrumentation. Conclusion. In comparison to rotary and manual instrumentation, postoperative pain severity was reduced with adaptive instrumentation.
Fouling Control Strategies for High Concentrated Liquid Desiccants Concentrating Using Membrane Distillation
Authors: Ha Seonguk , Lee Jieun , Jeong Seongeom , Jeong Sanghyun
Published: February 2023

Air conditioning using a liquid desiccant (LD) is an energy-efficient air purification and cooling system. However, high energy is required to concentrate or regenerate the LD. This study aimed to investigate the characteristics of membrane fouling in more detail and determine control strategies for LD concentrating using membrane distillation (MD). Two different LDs—lithium chloride (LiCl) and potassium formate (HCOOK)—were used. Because LDs require high concentrations by nature (i.e., 40 wt% for LiCl and 70 wt% for HCOOK), the concentration was started from half of those concentrations. This resulted in a flux decline with severe membrane fouling during the concentration using MD. Different membrane fouling mechanisms were also observed, depending on the LD type. Three different physical membrane fouling control methods, including water flushing (WF), air backwashing (AB), and membrane spacer (SP), were introduced. Results showed that WF was the most effective. Both AB and SP showed a marginal change to no cleaning; however, an initial flux with SP was about 1.5 times higher than no cleaning. Therefore, WF combined with the SP could maintain a high flux and a low fouling propensity in the treatment of a high-concentration solution using MD.
Remodeling of Biomembranes and Vesicles by Adhesion of Condensate Droplets
Authors: Lipowsky Reinhard
Published: February 2023

Condensate droplets are formed in aqueous solutions of macromolecules that undergo phase separation into two liquid phases. A well-studied example are solutions of the two polymers PEG and dextran which have been used for a long time in biochemical analysis and biotechnology. More recently, phase separation has also been observed in living cells where it leads to membrane-less or droplet-like organelles. In the latter case, the condensate droplets are enriched in certain types of proteins. Generic features of condensate droplets can be studied in simple binary mixtures, using molecular dynamics simulations. In this review, I address the interactions of condensate droplets with biomimetic and biological membranes. When a condensate droplet adheres to such a membrane, the membrane forms a contact line with the droplet and acquires a very high curvature close to this line. The contact angles along the contact line can be observed via light microscopy, lead to a classification of the possible adhesion morphologies, and determine the affinity contrast between the two coexisting liquid phases and the membrane. The remodeling processes generated by condensate droplets include wetting transitions, formation of membrane nanotubes as well as complete engulfment and endocytosis of the droplets by the membranes.
Nylon 6,6 Waste Nanofiber Membrane for Produced Water Filtration: Experimental, Performance Modelling, Optimization and Techno-Economic Analysis
Authors: Abd Halim Nur Syakinah , Mohd Hizam Shafiq , Wan Suhaimi Wan Mohamad Syameer , Ahmad Farid Ahmad Syahmi , Abd Rahman Puteri Nur Khaliesah , Wirzal Mohd Dzul Hakim , Sambudi Nonni Soraya , Md Nordin Nik Abdul Hadi
Published: February 2023

Produced water (PW) is a by-product of oil and gas extraction, of which it is deemed as the primary contributor of wastewater stream in oil production. Conventional treatment such as membrane separation is favoured due to its sustainability and cost effectiveness. On the other hand, oceanic litters such as abandoned fishing nets endangered the marine life ecosystem, despite of its potential to be raw material for fabrication of nanofiber membrane (NFM). This study explores the potential usage of electrospun nylon 6,6 waste NFM for treatment of real PW. In terms of modelling, it is found that feed concentration is the dominant factor with R2 of 0.94 for permeate concentration response and 0.91 for average flux response. Moreover, the optimized system with average flux of 216.5 L/m2h with low specific power consumption of ca. 0.09 kWh/m3 is proven to be economically feasible with less than 5% error from predicted model. As for technoeconomic analysis, it is found that permeate flux plays the major role in controlling total capital cost (CAPEX) and operating cost (OPEX) of the system. The lowest total CAPEX and OPEX to achieve 10 ppm of permeate concentration, also was found to be RM 3.7 M and RM/year 1660, hence proving the economic feasibility of the proposed system.
Compound Casting of Aluminum with Sheet Steel in 3D Sand Casting Using an Inductive Heating System
Authors: Locke Christopher , Guggemos Martin , Gruber Maximilian , Maier Lorenz , Mayr Lukas , Weiß Tony , Volk Wolfram , Günther Daniel
Published: February 2023

Compound casting is a process in which a single component is made from two metallic materials, such as aluminum and steel. Solid-liquid bimetallic compounds can be produced by suitable process control. This technology can reduce the number of joining processes, and the specific properties of the respective metal component can be used for specifically designed product properties, for example, where lightweight and high strength are needed. This paper presents an experimental methodology for producing a purely material-bonded bimetallic joint from cast aluminum and zinc-coated sheet steel in 3D sand casting using an inductive heating system. The process-related temperature characterisation in the compound zone is described using a heating test rig and temperature measurements. It shows that inductive preheating can only produce a material bond between the aluminum casting and the coated steel sheet. Shear tensile tests showed strengths between 15 MPa and 22 MPa. Laser surface pre-treatment using laser ablation cutting on the coated steel sheet was carried out to investigate the benefit of possible microform-locking. The results show a strength-reducing influence on the tensile shear tests. Micrographs showed the formation of Al4.5FeSi and Al7Fe2Si, as well as the formation of other undefined intermetallic phases. The thickness of the compound zone is 10 µm.
Cold Compaction Behavior of Unsaturated Titanium Hydride Powders: Validation of Two Compaction Equations
Authors: Luo Liu , Sun Yuchu , Tang Yongbai
Published: February 2023

Unsaturated titanium hydride (TiHX) powder has high formability and is a promising raw material for titanium-based powder metallurgy. In this work, TiH2, TiHX, and HDH Ti powders were characterized, the cold compaction behavior of the powders was investigated, and the densification mechanism was analyzed. The TiHX was a three-phase mixture containing an α plastic phase and δ and ε brittle phases through Rietveld refinement. The TiHX compacts had compressive strength of over 420 MPa (higher than TiH2 and similar to HDHTi) and relative density of over 80% (higher than TiH2 and HDH Ti) at 600 MPa. The Gerdemann–Jablonski and Cooper–Eaton equation were used to simulate the powder compaction curves and describe powder compaction behavior. The plastic deformation of TiHX powder is greater than TiH2, and the particle rearrangement is greater than HDH Ti during cold compaction. Such compaction behavior of TiHX causes an excellent green-strength–relative-density combination.
Corrosion of Molybdenum-Based and Ni–Mo Alloys in Liquid Bismuth–Lithium Alloy
Authors: Abramov Aleksander V. , Alimgulov Ruslan R. , Trubcheninova Anastasia I. , Zhilyakov Arkadiy Yu. , Belikov Sergey V. , Volkovich Vladimir A. , Polovov Ilya B.
Published: February 2023

Bismuth–lithium alloys are considered primary candidates for the reductive extraction step in the on-line reprocessing of molten salt reactor fuel. The corrosion behavior of molybdenum-based alloys and Hastelloy® B-3 alloy (taken for comparison) was examined here in a liquid Bi–Li (5 mol.%) alloy at 650 °C. MoW10, MoW30, and TZM corrosion-resistant alloys were studied as prospective construction materials for holding liquid bismuth–lithium alloy. Rates of corrosion were determined by the gravimetric method as well as by chemical analysis of corrosion products formed in liquid-phase Bi–Li alloy. The microstructure and chemical composition of samples of the materials and Bi–Li alloys containing the corrosion products after the tests were determined using inductively coupled plasma–atomic emission spectroscopy, X-ray fluorescence analysis, scanning electron microscopy, and energy dispersive spectroscopy. TZM molybdenum-based alloy corrodes in the bismuth-lithium alloy due to the formation of a zirconium–bismuth intermetallic compound, which passes into the liquid phase. The corrosion rates of MoW10, MoW30, and TZM alloys at 650 °C were 16, 16, and 23 µm/year, respectively. Hastelloy® B-3 alloy, despite its high molybdenum content, was subjected to severe corrosion in liquid Bi–Li alloys due to dissolution of nickel in liquid bismuth. The corrosion rate of this alloy was 14 mm/year.
Effect of Lateral Laser-Cladding Process on the Corrosion Performance of Inconel 625
Authors: Rezayat Mohammad , Aboutorabi Sani Amirhossein , Talafi Noghani Mohammad , Saghafi Yazdi Morteza , Taheri Morteza , Moghanian Amirhossein , Mohammadi Mohammad Abedini , Moradi Mahmoud , Mateo García Antonio Manuel , Besharatloo Hossein
Published: February 2023

This study aimed to evaluate the corrosion properties of different samples coated by the laser-cladding method to find the optimal laser parameters. Thereby, potentiodynamic polarization (Tafel) and electrochemical impedance tests were performed to assess the corrosion resistance of coated samples. Consequently, the corrosion morphology of tested samples was inspected by scanning electron microscopy. The results demonstrated that the laser power directly correlates with pitting corrosion and defects on the surface of the samples. Moreover, when molybdenum and chromium ions are increased in the electrolyte solution, the passive and protective layers are more durable, as the ions are sited within the holes and defects, reducing the surface corrosion rate.
Numerical Simulation of Microstructure Evolution of Directionally Annealed Pure Iron by Cellular Automata
Authors: Zhou Rongyi , Feng Xiaohui , Zheng Ce , Huang Qiuyan , Li Yingju , Yang Yuansheng
Published: February 2023

In order to understand the effects of drawing velocity, initial grain size and texture on the microstructure evolution during directional annealing, a cellular automata model based on grain boundary (GB) curvature, GB energy and GB mobility was established with a modified calculation model of the GB curvature. The simulation results show that there is a lower limit and an upper limit to the drawing velocity for the formation of columnar grains, and the columnar grains can only be formed between the upper limit and the lower limit. The simulation results are consistent with the experimental results. When the drawing velocity is lower than the lower limit, the equiaxed grains grow at the front of the hot zone, which hinders the formation of the columnar grains. With the increase of initial grain size, the driving force of GB migration decreases, and the grain boundaries are difficult to move with the hot zone, which is not conducive to the formation of columnar grains. There is an upper limit of initial grain size for the formation of columnar grains. The abnormal growth induced by texture prevents the growth of columnar grains during directional annealing. The weaker the texture strength, the more conducive to the growth of columnar grains.
Gradient Recrystallization Behavior of a Moderate Warm-Rolled Non-Oriented Fe-6.5wt%Si Alloy
Authors: Xu Haijie , Xu Cheng , Jiang Lulan , Zhang Yuanxiang , Shu Xuedao , Lin Xiaogang
Published: February 2023

In Fe-Si alloy systems, the Fe-6.5wt%Si alloy shows low iron core losses and near-zero magnetostriction, thus having great potential for high-frequency applications. In this study, an Fe-6.5wt%Si alloy hot band was subjected to a moderate warm rolling with a thickness reduction of 40%, and then annealed at different temperatures. The recrystallization behavior was investigated using the EBSD technique. After the moderate warm rolling, the initial gradient structure of the hot band is inherited, leading to gradient recrystallization behaviors during the further annealing process. The sheet surface first densely nucleates and forms strong <110>//ND and {221}<114> textures. However, the <110>//ND and {221}<114> grains have fewer high-mobility and high-energy (20–45°) boundaries than the other oriented matrix grains, leading to insufficient growth advantages. In the center region, the recrystallization is slow, but the nuclei usually have larger sizes. The inheritance of the <001>//ND (θ-fiber) texture from the initial hot band appears. Some θ-fiber grains, which have easy-magnetized <001> axes lying in the sheet plane, preferentially nucleate in the strong α-fiber textured matrices and form a strong θ-fiber recrystallization texture in the center region.
Numerical Simulation of Low-Pressure Carburizing and Gas Quenching for Pyrowear 53 Steel
Authors: Iżowski Bartosz , Wojtyczka Artur , Motyka Maciej
Published: February 2023

The hardness and phase composition are, among other things, the critical material properties considered in the quality control of aerospace gears made from Pyrowear 53 steel after high-pressure gas quenching. The low availability of data on and applications of such demanding structures justify investigating the choice of the material and the need to improve its manufacturability. In this study, computational finite-element analyses of low-pressure carburizing followed by oil and gas quenching of Pyrowear 53 steel were undertaken, the objective of which was to examine the influence of the process parameters on the materials’ final phase composition and hardness. The material input was prepared using JMatPro. The properties computed by the CALPHAD method were calibrated by the values obtained from physical experiments. The heat transfer coefficient was regarded as an objective variable to be optimized. A 3D model of the Standard Navy C-ring specimen was utilized to predict the phase composition after the high-pressure gas quenching of the steel and the hardness at the final stage. These two parameters are considered good indicators of the actual process parameters and are used in the industry. The results of the simulation, e.g., optimized heat transfer coefficients, cooling curves, and hardness and phase composition, are presented and compared with experimental values. The accuracy of the simulation was validated, and a good correlation of the data was found, which demonstrates the quality of the input data and setup of the numerical procedure. A computational approach to heat treatment processes’ design could contribute to accelerating new procedures’ implementation and lowering the development costs.
Application of Deep Learning Techniques to Predict the Mechanical Strength of Al-Steel Explosive Clads
Authors: Saravanan Somasundaram , Kumararaja Kanagasabai , Raghukandan Krishnamurthy
Published: February 2023

In this study, the tensile and shear strengths of aluminum 6061-differently grooved stainless steel 304 explosive clads are predicted using deep learning algorithms, namely the conventional neural network (CNN), deep neural network (DNN), and recurrent neural network (RNN). The explosive cladding process parameters, such as the loading ratio (mass of the explosive/mass of the flyer plate, R: 0.6–1.0), standoff distance, D (5–9 mm), preset angle, A (0–10°), and groove in the base plate, G (V/Dovetail), were varied in 60 explosive cladding trials. The deep learning algorithms were trained in a Python environment using the tensile and shear strengths acquired from 80% of the experiments, using trial and previous results. The remaining experimental findings are used to evaluate the developed models. The DNN model successfully predicts the tensile and shear strengths with an accuracy of 95% and less than 5% deviation from the experimental result.
Simulation of Fluidization Quality for Various Reduced−Gas Composition and Agitation Speed Circumstances in a Gas-Solid Fluidized Bed with an Inclined Agitator
Authors: Li Chuanfu , Liu Yan , Wu Yuelong , Li Xiaolong , Zhang Tingan
Published: February 2023

Blast furnace ironmaking is one of the most serious carbon dioxide emission processes. To reduce energy consumption and CO2 emissions, fluidized bed ironmaking technology with hydrogen as a reducing agent has attracted more and more attention. An inclined agitator was added to the fluidized bed reactor to address the sticking issue in the conventional fluidized bed ironmaking process. In this research, numerical simulation was used to examine the impacts of reducing gas composition and agitation speed on the gas-solid fluidization quality in the cold fluidization of iron ore powder in the fluidized bed with an inclined agitator. The results indicate that the fluidization effect of iron ore powder is better when the volume ratios of H2 to CO and H2 to N2 are 1:1. Under the intensive shear action of the agitator, the standard deviation of pressure drop constantly decreases with the increase in agitation speed, and the decreasing range is smaller and smaller. The fluidization state of the iron ore powder particles in the bed stabilized when the agitation speed reached 160 rpm.
Salivary Metabolomic Analysis Reveals Amino Acid Metabolism Shift in SARS-CoV-2 Virus Activity and Post-Infection Condition
Authors: da Silva Fidalgo Tatiana Kelly , Freitas-Fernandes Liana Bastos , Marques Barbara Bruno Fagundes , de Araújo Caroline Souza , da Silva Bruno Jefferson , Guimarães Taísa Coelho , Fischer Ricardo Guimarães , Tinoco Eduardo Muniz Barretto , Valente Ana Paula
Published: February 2023

The SARS-CoV-2 virus primarily infects salivary glands suggesting a change in the saliva metabolite profile; this shift may be used as a monitoring instrument during SARS-CoV-2 infection. The present study aims to determine the salivary metabolomic profile of patients with and post-SARS-CoV-19 infection. Patients were without (PCR−), with SARS-CoV-2 (PCR+), or post-SARS-CoV-2 infection. Unstimulated whole saliva was collected, and the 1H spectra were acquired in a 500 MHz Bruker nuclear magnetic resonance spectrometer at 25 °C. They were subjected to multivariate analysis using principal component analysis (PCA) and partial least squares discriminant analysis (PLS-DA), as well as univariate analysis through t-tests (SPSS 20.0, IL, USA), with a significance level of p < 0.05. A distinction was found when comparing PCR− subjects to those with SARS-CoV-2 infection. When comparing the three groups, the PLS-DA cross-validation presented satisfactory accuracy (ACC = 0.69, R2 = 0.39, Q2 = 0.08). Seventeen metabolites were found in different proportions among the groups. The results suggested the downregulation of major amino acid levels, such as alanine, glutamine, histidine, leucine, lysine, phenylalanine, and proline in the PCR+ group compared to the PCR− ones. In addition, acetate, valerate, and capronic acid were higher in PCR− patients than in PCR+. Sucrose and butyrate were higher in post-SARS-CoV-2 infection compared to PCR−. In general, a reduction in amino acids was observed in subjects with and post-SARS-CoV-2 disease. The salivary metabolomic strategy NMR-based was able to differentiate between non-infected individuals and those with acute and post-SARS-CoV-19 infection.
Dietary Stimuli, Intestinal Bacteria and Peptide Hormones Regulate Female Drosophila Defecation Rate
Authors: Kotronarou Katerina , Charalambous Anna , Evangelou Amalia , Georgiou Olympiada , Demetriou Andri , Apidianakis Yiorgos
Published: February 2023

Peptide hormones control Drosophila gut motility, but the intestinal stimuli and the gene networks coordinating this trait remain poorly defined. Here, we customized an assay to quantify female Drosophila defecation rate as a proxy of intestinal motility. We found that bacterial infection with the human opportunistic bacterial pathogen Pseudomonas aeruginosa (strain PA14) increases defecation rate in wild-type female flies, and we identified specific bacteria of the fly microbiota able to increase defecation rate. In contrast, dietary stress, imposed by either water-only feeding or high ethanol consumption, decreased defecation rate and the expression of enteroendocrine-produced hormones in the fly midgut, such as Diuretic hormone 31 (Dh31). The decrease in defecation due to dietary stress was proportional to the impact of each stressor on fly survival. Furthermore, we exploited the Drosophila Genetic Reference Panel wild type strain collection and identified strains displaying high and low defecation rates. We calculated the narrow-sense heritability of defecation rate to be 91%, indicating that the genetic variance observed using our assay is mostly additive and polygenic in nature. Accordingly, we performed a genome-wide association (GWA) analysis revealing 17 candidate genes linked to defecation rate. Downregulation of four of them (Pmp70, CG11307, meso18E and mub) in either the midgut enteroendocrine cells or in neurons reduced defecation rate and altered the midgut expression of Dh31, that in turn regulates defecation rate via signaling to the visceral muscle. Hence, microbial and dietary stimuli, and Dh31-controlling genes, regulate defecation rate involving signaling within and among neuronal, enteroendocrine, and visceral muscle cells.
An Archetypical Model for Engrafting Bacteroides fragilis into Conventional Mice Following Reproducible Antibiotic Conditioning of the Gut Microbiota
Authors: Eribo Osagie A. , Naidoo Charissa C. , Theron Grant , Walzl Gerhard , du Plessis Nelita , Chegou Novel N.
Published: February 2023

Bacteroides fragilis is a commonly investigated commensal bacterium for its protective role in host diseases. Here, we aimed to develop a reproducible antibiotic-based model for conditioning the gut microbiota and engrafting B. fragilis into a conventional murine host. Initially, we selected different combinations of antibiotics, including metronidazole, imipenem, and clindamycin, and investigated their efficacy in depleting the mouse Bacteroides population. We performed 16S rRNA sequencing of DNA isolated from fecal samples at different time points. The α-diversity was similar in mice treated with metronidazole (MET) and differed only at weeks 1 (p = 0.001) and 3 (p = 0.009) during metronidazole/imipenem (MI) treatment. Bacteroides compositions, during the MET and MI exposures, were similar to the pre-antibiotic exposure states. Clindamycin supplementation added to MET or MI regimens eliminated the Bacteroides population. We next repeated metronidazole/clindamycin (MC) treatment in two additional independent experiments, followed by a B. fragilis transplant. MC consistently and reproducibly eliminated the Bacteroides population. The depleted Bacteroides did not recover in a convalescence period of six weeks post-MC treatment. Finally, B. fragilis was enriched for ten days following engraftment into Bacteroides-depleted mice. Our model has potential use in gut microbiota studies that selectively investigate Bacteroides’ role in diseases of interest.
Association between Gut Microbiota and SARS-CoV-2 Infection and Vaccine Immunogenicity
Authors: Ng Ho Yu , Leung Wai K. , Cheung Ka Shing
Published: February 2023

Gut microbiota is increasingly recognized to play a pivotal role in various human physiological functions and diseases. Amidst the COVID-19 pandemic, research has suggested that dysbiosis of the gut microbiota is also involved in the development and severity of COVID-19 symptoms by regulating SARS-CoV-2 entry and modulating inflammation. Previous studies have also suggested that gut microbiota and their metabolites could have immunomodulatory effects on vaccine immunogenicity, including influenza vaccines and oral rotavirus vaccines. In light of these observations, it is possible that gut microbiota plays a role in influencing the immune responses to COVID-19 vaccinations via similar mechanisms including effects of lipopolysaccharides, flagellin, peptidoglycan, and short-chain fatty acids. In this review, we give an overview of the current understanding on the role of the gut microbiota in COVID-19 manifestations and vaccine immunogenicity. We then discuss the limitations of currently published studies on the associations between gut microbiota and COVID-19 vaccine outcomes. Future research directions shall be focused on the development of microbiota-based interventions on improving immune response to SARS-CoV-2 infection and vaccinations.
Sustainable Applications of Endophytic Bacteria and Their Physiological/Biochemical Roles on Medicinal and Herbal Plants: Review
Authors: Tshikhudo Phumudzo Patrick , Ntushelo Khayalethu , Mudau Fhatuwani Nixwell
Published: February 2023

Bacterial endophytes reside within the tissues of living plant species without causing any harm or disease to their hosts. These endophytes can be isolated, identified, characterized, and used as biofertilizers. Moreover, bacterial endophytes increase the plants’ resistance against diseases, pests, and parasites, and are a promising source of pharmaceutically important bioactives. For instance, the production of antibiotics, auxins, biosurfactants, cytokinin’s, ethylene, enzymes, gibberellins, nitric oxide organic acids, osmolytes, and siderophores is accredited to the existence of various bacterial strains. Thus, this manuscript intends to review the sustainable applications of endophytic bacteria to promote the growth, development, and chemical integrity of medicinal and herbal plants, as well as their role in plant physiology. The study of the importance of bacterial endophytes in the suppression of diseases in medicinal and herbal plants is crucial and a promising area of future investigation.