bluuebunny/crossref_metadata_2025 huggingface dataset:
Fretting Fatigue in Mechanical Joints: A Literature Review
Authors: Croccolo Dario , De Agostinis Massimiliano , Fini Stefano , Olmi Giorgio , Robusto Francesco , Scapecchi Chiara
Published: March 2022

Fretting fatigue is a fatigue damage process that occurs when two surfaces in contact with each other are subjected to relative micro-slip, causing a reduced fatigue life with respect to the plain fatigue case. Fretting has now been studied deeply for over 50 years, but still no univocal design approach has been universally accepted. This review presents a literature study that involves the three main types of mechanical joint affected by fretting fatigue (press-fitted shaft hub joints, dovetail joints, and bolted joints) aiming at giving insight into the progress made in terms of design guidelines for engineers.
Correction: Al-Qhtani et al. Half Metallic Ferromagnetism and Transport Properties of Zinc Chalcogenides ZnX2Se4 (X = Ti, V, Cr) for Spintronic Applications. Materials 2022, 15, 55
Authors: Al-Qhtani Mohsen , Mustafa Ghulam M. , Mazhar Nasheeta , Bouzgarrou Sonia , Mahmood Qasim , Mera Abeer , Zaki Zaki I. , Mostafa Nasser Y. , Alotaibi Saad , Amin Mohammed
Published: March 2022

In the original publication [...]
A Combination of Calcination and the Spark Plasma Sintering Method in Multiferroic Ceramic Composite Technology: Effects of Process Temperature and Dwell Time
Authors: Bochenek Dariusz
Published: March 2022

This study reports a combined technological process that includes synthesis by the calcination powder route and sintering by the Spark Plasma Sintering (SPS) method for multiferroic ceramic composites in order to find the optimal sintering conditions. The effects of temperature on the SPS process and dwell time on the microstructure and dielectric properties of the PF composites were discussed. Research has shown that using the SPS method in the technological process of the multiferroic composites favors the correct densification of powders and allows for obtaining a fine-grained microstructure with good properties and electrophysical parameters in the composite material. The optimal set of parameters and properties is demonstrated by the sample obtained at the temperature of 900 °C for 3 min, i.e., resistivity (6.4 × 108 Ωm), values of the dielectric loss factor (0.016), permittivity at room temperature (753) and permittivity at the phase transition temperature (3290). Moreover, due to the high homogeneity of the microstructure, the strength of the material against electric breakdown increases (when examining the ferroelectric hysteresis loop, the application of a high electric field (3—3.5 kV/mm) is also possible at higher temperatures). In the case of the composite material tested, both the lower and higher temperatures as well as the shorter and longer dwell times (compared to the optimal SPS process conditions) did not contribute to the improvement of the microstructure or the set of usable parameters of the composite materials. The strength of the ceramic samples against electric breakdown has also diminished, while the phenomenon of leakage current increased.
A Step towards Concrete with Partial Substitution of Waste Glass (WG) in Concrete: A Review
Authors: Ahmad Jawad , Zhou Zhiguang , Usanova Kseniia Iurevna , Vatin Nikolai Ivanovich , El-Shorbagy Mohammed A.
Published: March 2022

The annual worldwide production rate of waste glass is a million tons; the waste glass is non-biodegradable, resulting in environmental pollution. However, the chemical composition of waste glass (WG) is promoted to be used as a partial substitution of binding or filler (aggregate) material in concrete production. Although significant research has been conducted in this area, the results of these studies are scattered, and it is difficult to judge the suitability of waste glass in concrete. This review looks at the effects of waste glass on concrete’s fresh, mechanical, and durability properties. It concludes that waste glass decreased the flowability of concrete. Furthermore, waste glass can be used as pozzolanic material, creating secondary cementitious compound (CSH) gel. CSH gel increased the cement paste’s binding properties, leading to increased mechanical performance. Moreover, this study reveals that the optimum dose of waste glass is important to minimize the possibility of an alkali–silica reactions. Based on this review, most researchers conclude that 20% substitution of waste glass as binding material is the optimum dose. The wide range of discussion provides the necessary guideline for the best research practice in the future.
Self-Cleaning Biomimetic Surfaces—The Effect of Microstructure and Hydrophobicity on Conidia Repellence
Authors: Alon Haguy , Vitoshkin Helena , Ziv Carmit , Gunamalai Lavanya , Sinitsa Sergey , Kleiman Maya
Published: March 2022

Modification of surface structure for the promotion of food safety and health protection is a technology of interest among many industries. With this study, we aimed specifically to develop a tenable solution for the fabrication of self-cleaning biomimetic surface structures for agricultural applications such as post-harvest packing materials and greenhouse cover screens. Phytopathogenic fungi such as Botrytiscinerea are a major concern for agricultural systems. These molds are spread by airborne conidia that contaminate surfaces and infect plants and fresh produce, causing significant losses. The research examined the adhesive role of microstructures of natural and synthetic surfaces and assessed the feasibility of structured biomimetic surfaces to easily wash off fungal conidia. Soft lithography was used to create polydimethylsiloxane (PDMS) replications of Solanum lycopersicum (tomato) and Colocasia esculenta (elephant ear) leaves. Conidia of B. cinerea were applied to natural surfaces for a washing procedure and the ratios between applied and remaining conidia were compared using microscopy imaging. The obtained results confirmed the hypothesis that the dust-repellent C. esculenta leaves have a higher conidia-repellency compared to tomato leaves which are known for their high sensitivities to phytopathogenic molds. This study found that microstructure replication does not mimic conidia repellency found in nature and that conidia repellency is affected by a mix of parameters, including microstructure and hydrophobicity. To examine the effect of hydrophobicity, the study included measurements and analyses of apparent contact angles of natural and synthetic surfaces including activated (hydrophilic) surfaces. No correlation was found between the surface apparent contact angle and conidia repellency ability, demonstrating variation in washing capability correlated to microstructure and hydrophobicity. It was also found that a microscale sub-surface (tomato trichromes) had a high conidia-repelling capability, demonstrating an important role of non-superhydrophobic microstructures.
Adsorption Study of Novel Gemini Cationic Surfactant in Carbonate Reservoir Cores—Influence of Critical Parameters
Authors: Khan Sarmad , Gbadamosi Afeez , Norrman Kion , Zhou Xianmin , Hussain Syed Muhammad Shakil , Patil Shirish , Kamal Muhammad Shahzad
Published: March 2022

Surfactant flooding is an enhanced oil recovery method that recovers residual and capillary trapped oil by improving pore-scale displacement efficiency. Low retention of injected chemicals is desired to ensure an economic and cost-effective recovery process. This paper examines the adsorption behavior of a novel gemini cationic surfactant on carbonate cores. The rock cores were characterized using an X-ray diffraction (XRD) spectroscope. In addition, the influence of critical parameters on the dynamic adsorption of the cationic gemini surfactant was studied by injecting the surfactant solution through carbonate cores in a core flooding apparatus until an equilibrium state was achieved. The concentration of surfactant was observed using high performance liquid chromatography. Experimental results showed that an increasing surfactant concentration causes higher retention of the surfactant. Moreover, increasing the flow rate to 0.2 mL/min results in lowering the surfactant retention percentage to 17%. At typical high salinity and high temperature conditions, the cationic gemini surfactant demonstrated low retention (0.42 mg/g-rock) on an Indiana limestone core. This study extends the frontier of knowledge in gemini surfactant applications for enhanced oil recovery.
Investigation of the Initial Corrosion Destruction of a Metal Matrix around Different Non-Metallic Inclusions on Surfaces of Pipeline Steels
Authors: Sidorova Elena , Karasev Andrey , Kuznetsov Denis , Jönsson Pär G.
Published: March 2022

Typical non-metallic inclusions in two industrial low-carbon steels for oil pipelines were investigated as three-dimensional objects on film filters after electrolytic extraction and filtration of metal samples. A method of soft chemical extraction using a 10%AA electrolyte was used to study the initial corrosion process in the steel matrix surrounding various non-metallic inclusions. To determine and compare “corrosive” inclusions and their influence on the initial stages of corrosion of the adjacent layer of the steel matrix, quantitative parameters (such as the diameter of the corrosion crater (Dcr) and pit (Dpit), and the relative dissolution coefficient of the metal matrix (KD) around various inclusions) were determined after chemical extraction. It was found that CaO-Al2O3-MgO oxides and TiN inclusions did not cause an initial corrosion of the steel matrix surrounding these inclusions. However, tensile stresses in the steel matrix occurred around CaS inclusions (or complex inclusions containing a CaS phase), which contributed to the initiation of corrosion around these inclusions.
Experimental and Simulation Investigation of Nd Additions on As-Cast Microstructure and Precipitate Development in Mg–Nd System Alloys
Authors: Yan Xuewei , Su Bin , Yang Xuemei , Xu Qingdong , Zhang Xiaopeng , Wang Jing , Wen Zhenhua
Published: March 2022

The microstructure and precipitate evolution of as-cast Mg–Nd alloys with different contents of Nd was investigated via experimental and simulation methods. The research showed that the as-cast microstructure of Mg–Nd alloy consisted of α-Mg dendrites and the intermetallic phases. A metastable β phase precipitated, followed by α-Mg dendrites that could be confirmed as Mg12Nd by X-ray diffraction (XRD) analysis. The amount of β-Mg12Nd presented a rising trend with increasing Nd additions. In addition, the tertiary phase was also observed in as-cast Mg–Nd alloy when Nd content was greater than 3 wt.%, which precipitated from the oversaturated α-Mg matrix. The tertiary phase should be β1-Mg3Nd, which is also a metastable phase with a face-centered cubic lattice. However, it is a pity that the tertiary phase was not detected by the XRD technique. Moreover, an effective cellular automaton (CA) model was explored and applied to simulate the time-dependent α-Mg/β1-Mg3Nd eutectic growth. The simulated results of α-Mg/β1-Mg3Nd eutectic growth in Mg-3Nd presented that the growth of α-Mg dendrites was accompanied by the nucleation and growth of β1-Mg3Nd precipitates and eventually formed a eutectic structure. The eutectic morphologies for Mg–Nd system alloys with different Nd contents were also simulated using the proposed model, and the results revealed that α-Mg dendrite was a refinement, and the amount of α-Mg/β1-Mg3Nd eutectic was promoted, with increasing Nd content.
A Novel Impact Feature Extraction Method Based on EMD and Sparse Decomposition for Gear Local Fault Diagnosis
Authors: Liu Zhongze , Ding Kang , Lin Huibin , He Guolin , Du Canyi , Chen Zhuyun
Published: March 2022

Sparse decomposition has been widely used in gear local fault diagnosis due to its outstanding performance in feature extraction. The extraction results depend heavily on the similarity between dictionary atoms and fault feature signal. However, the transient impact signal aroused by gear local defect is usually submerged in meshing harmonics and noise. It is still a challenging task to construct high-quality impact dictionary for complex actual signal. To handle this issue, a novel impact feature extraction method based on Empirical Mode Decomposition (EMD) and sparse decomposition is proposed in this paper. Firstly, EMD is employed to adaptively decompose the original signal into several Intrinsic Mode Functions (IMFs). The high-frequency resonance component is separated from meshing harmonics and part of the noise. Then, the IMF with the prominent impact features is selected as the Main Intrinsic Mode Function (MIMF) based on the kurtosis. Accordingly, the modal parameters required for impact dictionary are identified from the MIMF by correlation filtering. Finally, the transient impact component is extracted from the original signal by Match Pursuit (MP). The proposed method was adequately evaluated by a gear local fault simulation signal, and the single-stage gearbox and five-speed transmission experiments. The effectiveness and superiority of the proposed method is validated by comparison with other feature extraction techniques.
Multi-Objective Design Optimization of Flexible Manufacturing Systems Using Design of Simulation Experiments: A Comparative Study
Authors: Jerbi Abdessalem , Hachicha Wafik , Aljuaid Awad M. , Masmoudi Neila Khabou , Masmoudi Faouzi
Published: March 2022

One of the basic components of Industry 4.0 is the design of a flexible manufacturing system (FMS), which involves the choice of parameters to optimize its performance. Discrete event simulation (DES) models allow the user to understand the operation of dynamic and stochastic system performance and to support FMS diagnostics and design. In combination with DES models, optimization methods are often used to search for the optimal designs, which, above all, involve more than one objective function to be optimized simultaneously. These methods are called the multi-objective simulation–optimization (MOSO) method. Numerous MOSO methods have been developed in the literature, which spawned many proposed MOSO methods classifications. However, the performance of these methods is not guaranteed because there is an absence of comparative studies. Moreover, previous classifications have been focused on general MOSO methods and rarely related to the specific area of manufacturing design. For this reason, a new conceptual classification of MOSO used in FMS design is proposed. After that, four MOSO methods are selected, according to this classification, and compared through a detailed case study related to the FMS design problem. All of these methods studied are based on Design of Experiments (DoE). Two of them are metamodel-based approaches that integrate Goal Programming (GP) and Desirability Function (DF), respectively. The other two methods are not metamodel-based approaches, which integrate Gray Relational Analysis (GRA) and the VIKOR method, respectively. The comparative results show that the GP and VIKOR methods can result in better optimization than DF and GRA methods. Thus, the use of the simulation metamodel cannot prove its superiority in all situations.
Toward Prevention of Parasite Chain Attack in IOTA Blockchain Networks by Using Evolutionary Game Model
Authors: Chen Yinfeng , Guo Yu , Wang Yaofei , Bie Rongfang
Published: March 2022

IOTA is a new cryptocurrency system designed for the Internet of Things based on directed an acyclic graph structure. It has the advantages of supporting high concurrency, scalability, and zero transaction fees; however, due to the particularity of the directed acyclic graph structure, IOTA faces more complex security threats than the sequence blockchain, in which a parasite chain attack is a common double-spending attack. In this work, we propose a scheme that can effectively prevent parasite chain attacks to improve the security of the IOTA ledger. Our main idea is to analyze the behavior strategies of IOTA nodes based on evolutionary game theory and determine the key factors affecting the parasite chain attack and the restrictive relationship between them. Based on the above research, we provide a solution to resist the parasite chain attack and further prove the effectiveness of the scheme by numerical simulation. Finally, we propose the parasite chain attack prevention algorithms based on price splitting to effectively prevent the formation of the parasite chain.
Stability of Impulsive Stochastic Delay Systems with Markovian Switched Delay Effects
Authors: Hu Wei
Published: March 2022

In this paper, we investigate the pth moment exponential stability of impulsive stochastic delay systems with Markovian switched delay effects. The model we consider here is rather different from the models in the existing literature. In particular, the delay is a Markov chain, which is quite different from the traditional deterministic delay. By using the Markov chain theory, stochastic analysis theory, Razumikhin technology and the Lyaponov method, we derive a criterion of pth moment exponential stability for the suggested system. Finally, an example is provided to illustrate the effectiveness of the obtained result.
High-Throughput Screening of a Marine Compound Library Identifies Anti-Cryptosporidium Activity of Leiodolide A
Authors: Bone Relat Rachel M. , Winder Priscilla L. , Bowden Gregory D. , Guzmán Esther A. , Peterson Tara A. , Pomponi Shirley A. , Roberts Jill C. , Wright Amy E. , O’Connor Roberta M.
Published: March 2022

Cryptosporidium sp. are apicomplexan parasites that cause significant morbidity and possible mortality in humans and valuable livestock. There are no drugs on the market that are effective in the population most severely affected by this parasite. This study is the first high-throughput screen for potent anti-Cryptosporidium natural products sourced from a unique marine compound library. The Harbor Branch Oceanographic Institute at Florida Atlantic University has a collection of diverse marine organisms some of which have been subjected to medium pressure liquid chromatography to create an enriched fraction library. Numerous active compounds have been discovered from this library, but it has not been tested against Cryptosporidium parvum. A high-throughput in vitro growth inhibition assay was used to test 3764 fractions in the library, leading to the identification of 23 fractions that potently inhibited the growth of Cryptosporidium parvum. Bioassay guided fractionation of active fractions from a deep-sea sponge, Leiodermatium sp., resulted in the purification of leiodolide A, the major active compound in the organism. Leiodolide A displayed specific anti-Cryptosporidium activity at a half maximal effective concentration of 103.5 nM with selectivity indexes (SI) of 45.1, 11.9, 19.6 and 14.3 for human ileocecal colorectal adenocarcinoma cells (HCT-8), human hepatocellular carcinoma cells (Hep G2), human neuroblastoma cells (SH-SY5Y) and green monkey kidney cells (Vero), respectively. The unique structure of leiodolide A provides a valuable drug scaffold on which to develop new anti-Cryptosporidium compounds and supports the importance of screening natural product libraries for new chemical scaffolds.
The Chemically Highly Diversified Metabolites from the Red Sea Marine Sponge Spongia sp.
Authors: Tai Chi-Jen , Ahmed Atallah F. , Chao Chih-Hua , Yen Chia-Hung , Hwang Tsong-Long , Chang Fang-Rong , Huang Yusheng M. , Sheu Jyh-Horng
Published: March 2022

A polyoxygenated and halogenated labdane, spongianol (1); a polyoxygenated steroid, 3β,5α,9α-trihydroxy-24S-ethylcholest-7-en-6-one (2); a rare seven-membered lactone B ring, (22E,24S)-ergosta-7,22-dien-3β,5α-diol-6,5-olide (3); and an α,β-unsaturated fatty acid, (Z)-3-methyl-9-oxodec-2-enoic acid (4) as well as five known compounds, 10-hydroxykahukuene B (5), pacifenol (6), dysidamide (7), 7,7,7-trichloro-3-hydroxy-2,2,6-trimethyl-4-(4,4,4-trichloro-3-methyl-1-oxobu-tylamino)-heptanoic acid methyl ester (8), and the primary metabolite 2’-deoxynucleoside thymidine (9), have been isolated from the Red Sea sponge Spongia sp. The stereoisomer of 3 was discovered in Ganoderma resinaceum, and metabolites 5 and 6, isolated previously from red algae, were characterized unprecedentedly in the sponge. Compounds 7 and 8 have not been found before in the genus Spongia. Compounds 1–9 were also assayed for cytotoxicity as well as antibacterial and anti-inflammatory activities.
Prognostic Gene Predictors of Gestational Diabetes in Endometrium and Follicular Fluid of Women after Infertility
Authors: Vaigauskaitė Brigita , Baušytė Raminta , Valatkaitė Elvina , Skliutė Giedrė , Kazėnaitė Edita , Ramašauskaitė Diana , Navakauskienė Rūta
Published: March 2022

Background and objectives. Gestational diabetes mellitus is an increasingly diagnosed metabolic disorder during pregnancy with unknown pathological pathways. Taking into account the growing numbers of women who are conceiving after assisted reproductive technologies, they comprise an engaging target group for gestational diabetes mellitus etiopathogenesis research. In terms of metabolism and genetics, as the evidence shows, both unexplained infertility and gestational diabetes mellitus pose challenges for their interpretation due to the complex bodily processes. Materials and Methods. Our study examined the expression of genes (IGF2, GRB10, CRTC2, HMGA2, ESR1, DLK1, SLC6A15, GPT2, PLAGL1) associated with glucose metabolism in unexplained infertility patients who conceived after in vitro fertilization procedure, were diagnosed with GDM and their findings were compared with control population. Results. There were no significant differences in gene expression of endometrium stromal cells between healthy pregnant women and women with gestational diabetes, although the significant downregulation of CRTC2 was observed in the follicular fluid of women with gestational diabetes mellitus. Moreover, expression of HMGA2 and ESR1 was significantly reduced in FF cells when compared to endometrial cells. Conclusions. These findings may indicate about the importance of follicular fluid as an indicator for gestational diabetes and should be explored more by further research.
Antioxidant and Antimicrobial Properties of Mung Bean Phyto-Film Combined with Longkong Pericarp Extract and Sonication
Authors: Keawpeng Ittiporn , Paulraj Balaji , Venkatachalam Karthikeyan
Published: March 2022

Mung bean (Vigna radiata) flour serves as an excellent biopolymer and a potential material for producing antioxidant and antimicrobial phyto-films. In addition to mung bean flour, this study also combined the longkong (Aglaia dookkoo Griff.) pericarp extract (LPE, 1.5%) and ultrasonication process (0 (C1), 2 (T1), 4 (T2), 6 (T3), 8 (T4), and 10 (T5) min, sonicated at 25 kHz, 100% amplitude) in film emulsion production to improve the antioxidant and antimicrobial efficiency in the phyto-films. This study showed that sonication increased the phyto-films’ color into more lightness and yellowness, and the intensity of the color changes was in accordance with the increased sonication time. Alternatively, the thickness, water vapor permeability, and solubility of the films were adversely affected by extended sonication. In addition, elongation at break and tensile strength increased while the Young modulus decreased in the phyto-films with the extended sonication. Furthermore, the droplet size and polydispersity index of the phyto-films decreased with extended sonication. Conversely, the zeta potential of the film tended to increase with the treatments. Furthermore, phytochemicals such as total phenolic content and total flavonoid contents, and the radical scavenging ability of phyto-films against the DPPH radical, ABTS radical, superoxide radical, hydroxyl radical, and ferrous chelating activity, were significantly higher, and they were steadily increased in the films with the extended sonication time. Furthermore, the phyto-films showed a significant control against Gram (-) pathogens, followed by Gram (+) pathogens. A higher inhibitory effect was noted against L. monocytogens, followed by S. aureus and B. subtilis. Similarly, the phyto-films also significantly inhibited the Gram (-) pathogens, and significant control was noted against C. jejuni, followed by E. coli and P. aeruginosa. Regardless of the mung bean flour, this study found that longkong pericarp extract and the sonication process could also effectively be used in the film emulsions to enhance the efficiency of the antioxidant and antimicrobial properties of phyto-films.
Grinding and Concentration Technology of Critical Metals
Authors: Menéndez Aguado Juan M.
Published: March 2022

The production and supply of raw materials in a global market are not without risks, and both the recent COVID-19 pandemic and the current one (Russia–Ukrania conflict) raised public awareness about the importance of multiple value chains [...]
Initiation Mechanism of Localized Corrosion Induced by Al2O3-MnS Composite Inclusion in Low-Alloy Structural Steel
Authors: Liu Chao , Yuan Hao , Li Xuedong , Che Zhichao , Yang Shufeng , Du Cuiwei
Published: March 2022

The present work systematically investigated the initiation mechanism of localized corrosion induced by Al2O3-MnS composite inclusion in E690 steel under a simulated marine environment. The results showed that a micro-gap exists between the Al2O3-MnS inclusion and the matrix, and electron backscattered diffraction (EBSD) analysis revealed significant lattice dislocation zones around the Al2O3-MnS composite inclusion. The presence of the micro-gap and the lattice dislocation both promoted the localized corrosion initiation. The Volta potential of Al2O3 detected by scanning Kelvin probe force microscopy (SKPFM) was approximately 149.33 mV higher than that of the steel matrix, and the Volta potential of MnS was 10 mV lower than that of the steel matrix. The current-sensing atomic force microscopy (CSAFM) results showed that the Al2O3 was not conductive, while the MnS had good conductive properties. Therefore, it was not possible for a galvanic couple to be formed between Al2O3 and the adjacent steel matrix. A galvanic couple effect between the MnS and the adjacent steel matrix was directly demonstrated for the first time. The MnS acted as the anode phase for preferential dissolution in the corrosion process. The in situ immersion experiments and the Pourbaix diagram results confirmed that the dissolution of MnS was an electrochemical reaction process and the dissolution of Al2O3 was a chemical reaction.
Investigation on Corrosion Resistance Properties of 17-4 PH Bound Metal Deposition As-Sintered Specimens with Different Build-Up Orientations
Authors: Forcellese Pietro , Mancia Tommaso , Simoncini Michela , Bellezze Tiziano
Published: March 2022

Additive manufacturing is a promising and emerging technology that can transform the global manufacturing and logistics by cutting costs and times of production. Localized corrosion resistance properties of 0°, 45°, and 90° build-up orientations of 17-4 PH as-sintered samples, manufactured by means of Bound Metal Deposition (BMD), have been investigated by electrochemical and morphological investigations. The cyclic potentiodynamic polarization curves and the open circuit potential monitoring, together with potential drop analysis, revealed that the BMD localized corrosion resistance properties were lowered if compared to a wrought 17-4 PH: a characteristic anodic behavior and many drops in potential were recorded for BMD, whilst the wrought specimens presented a typical passive behavior with pitting corrosion. Morphological investigations by scanning electron microscopy and energy-dispersive X-ray analysis revealed the presence of porosities and defects, especially for the 90° build-up orientation, and inclusions of SiO2. The 45° build-up orientation showed the best corrosion resistance properties among all the BMD specimens, even though defects and porosities were observed, suggesting that their morphology and geometry influenced the overall corrosion behavior.
Electrochemical Short-Time Testing Method for Simulating the Degradation Behavior of Magnesium-Based Biomaterials
Authors: Wegner Nils , Vergin Johanna , Walther Frank
Published: March 2022

In regenerative medicine, degradable, magnesium-based biomaterials represent a promising material class. The low corrosion resistance typical for magnesium is advantageous for this application since the entire implant degrades in the presence of the aqueous body fluids after fulfilling the intended function, making a second operation for implant removal obsolete. To ensure sufficient stability within the functional phase, the degradation behavior must be known for months. In order to reduce time and costs for these long-time investigations, an electrochemical short-time testing method is developed and validated, accelerating the dissolution process of a magnesium alloy with and without surface modification based on galvanostatic anodic polarization, enabling a simulation of longer immersion times. During anodic polarization, the hydrogen gas formed by the corrosion process increases linearly. Moreover, the gas volume shows a linear relationship to the dissolving mass, enabling a defined dissolution of magnesium. As a starting point, corrosion rates of both variants from three-week immersion tests are used. A simplified relationship between the current density and the dissolution rate, determined experimentally, is used to design the experiments. Ex situ µ-computed tomography scans are performed to compare the degradation morphologies of both test strategies. The results demonstrate that a simulation of the degradation rates and, hence, considerable time saving based on galvanostatic anodic polarization is possible. Since the method is accompanied by a changed degradation morphology, it is suitable for a worst-case estimation allowing the exclusion of new, unsuitable magnesium systems before subsequent preclinical studies.
Numerical and Theoretical Investigation on the Load-Carrying Capacity of Bolted Ball-Cylinder Joints with High-Strength Steel at Elevated Temperatures
Authors: He Jianian , Wu Baolong , Wu Nianduo , Chen Lexian , Chen Anyang , Li Lijuan , Xiong Zhe , Lin Jiaxiang
Published: March 2022

Bolted ball-cylinder (BBC) joints are suitable for non-purlin space structures to effectively reduce structure height and save material costs. In this paper, we present a numerical and theoretical study for high-strength steel BBC joints at elevated temperatures. An finite element (FE) model was first developed, in which the effects of elevated temperatures were considered by introducing reduction factors for the material properties of steel, such as the yield stress and Young’s modulus, to analyze the structural behavior of BBC joints subjected to compressive, tensile or bending loads. Based on parametric studies on 441 FE models, effects of the key parameters, including joint dimensions, material strength and temperatures, on the structural behavior of BBC joints are discussed. Then, theoretical analysis is conducted, and design methods are proposed to estimate the ultimate load-carrying capacity of BBC joints. Finally, we verified the accuracy of the design method by comparing the prediction with the FE results.
The Erosion–Corrosion Behavior of Eutectic High Chromium Cast Irons Reinforced by TiC Particles
Authors: Tu Tian-Quan , Liu Shen-Lin , Zheng Kai-Hong , Khina Boris B. , Pokrovsky Artur I. , Luo Zhi-Chao
Published: March 2022

In this work, high chromium cast irons (HCCIs) reinforced by TiC particles are designed and fabricated to improve the erosion–corrosion and wear resistances of materials for the pumping and handling applications. The TiC particles are formed by the in situ solidification method. The experimental results show that the hardness of as-cast HCCIs is improved significantly with TiC volume fraction. It can be as high as 63 HRC when the TiC volume fraction is 9.8%. The introduction of TiC increases the abrasive wear resistance of the HCCIs in both as-cast and heat-treated states. However, it is unexpected to find that the presence of TiC significantly reduces the erosion–corrosion performance. It suggests that corrosion-enhanced erosion is the dominant mechanism that controls the mass loss of the TiC-strengthened HCCIs.
Numerical Study on Elastic Buckling Behavior of Diagonally Stiffened Steel Plate Walls under Combined Shear and Non-Uniform Compression
Authors: Yang Yuqing , Mu Zaigen , Zhu Boli
Published: March 2022

Unstiffened steel plate walls (SPWs) are prone to buckling in practical engineering and will invariably be subjected to vertical loads. The use of stiffeners can improve the buckling behavior of thin plates. Considering the effect of the torsional stiffness of C-shaped stiffeners, the elastic buckling of the diagonally stiffened steel plate wall (DS-SPW) under combined shear and non-uniform compression is investigated. The interaction curves for the DS-SPW under combined action are presented, as well as a proposed equation for the elastic buckling coefficient. In addition, the effects of the stiffener’s flexural and torsional stiffness on the elastic buckling stress were investigated, and the threshold stiffness formulae were proposed. The results show that the interaction curve of the DS-SPW under combined shear and non-uniform compression is approximately parabolic. The critical buckling stress of the DS-SPW can be increased by increasing the stiffener’s torsional-to-flexure stiffness ratio and the non-uniform compression distribution factor, while the buckling stress can be decreased by increasing the non-uniform compression-to-shear ratio. Simultaneous action of shear and axial compression will increase the threshold stiffness by approximately 40% when compared to the plate under pure shear action. Therefore, the safety threshold stiffness formula is suggested, considering the combined action of shear and non-uniform compression.
Design and Optimization of a New Alternating Electromagnetic-Field-Generation System for an Inverted Microscope
Authors: Wu Zehao , Xu Ziheng , Xu Qingsong
Published: March 2022

This paper presents the design and optimization of a new alternating electromagnetic-field-generation system, which is dedicated to actuating untethered magnetic microrobots under an inverted microscope. Its uniqueness is that the system parameters are optimally designed by considering both electric and geometry constraints for the target-driving application. The dominant parameters of the system are first determined by establishing analytical models. According to the requirements of targeted application, the optimization problem with certain constraints is formulated, which is solved via the multiobjective genetic algorithm method. A prototype system with the optimal parameters is developed for experimental testing. Experimental studies are carried out to characterize actual performance of the developed actuation system. For demonstration, a magnetic microball has been actuated for navigation by surface rolling in a petri dish filled with pure water. Results indicate that the reported electromagnetic-field-generation system meets the actuation requirements for potential applications.
Hydrogen Storage Performance of γ-Graphdiyne Doped Li Based on First Principles for Micro/Nano
Authors: Tian Wenchao , Li Zhao , Cheng Chunmin , Li Wenhua , Chen Zhiqiang , Xin Fei
Published: March 2022

The rapid development of micro/nano systems promotes the progress of micro energy storage devices. As one of the most significant representatives of micro energy storage devices, micro hydrogen fuel cells were initially studied by many laboratories and companies. However, hydrogen storage problems have restricted its further commercialization. The γ-graphdiyne (γ-GDY) has broad application prospects in the fields of energy storage and gas adsorption due to its unique structure with rigid nano-network and numerous uniform pores. However, the existence of various defects in γ-GDY caused varying degrees of influence on gas adsorption performance. In this study, Lithium (Li) was added into the intrinsic γ-GDY and vacancy defect γ-GDY (γ-VGDY) to obtain the Li-GDY and Li-VGDY, respectively. The first-principles calculation method was applied and the hydrogen storage performances of them were analysed. The results indicated that the best adsorption point of intrinsic γ-GDY is H2 point, which located at the centre of a large triangular hole of an acetylene chain. With large capacity hydrogen storage, doping Li atom could improve the hydrogen adsorption property of intrinsic γ-GDY; meanwhile, vacancy defect inspires the hydrogen storage performance further of Li-VGDY. The mass hydrogen storage density for Li2H56-GDY and Li2H56-VGDY model were 13.02% and 14.66%, respectively. Moreover, the Li2H56-GDY and Li2H56-VGDY model had same volumetric storage density, with values that could achieve 5.22 × 104 kg/m3.
A Survey of the Influence of Process Parameters on Mechanical Properties of Fused Deposition Modeling Parts
Authors: Gao Ge , Xu Fan , Xu Jiangmin , Tang Guanghai , Liu Zhenyu
Published: March 2022

Due to the availability of materials and low cost for production, fused deposition modeling is becoming the most widely used additive manufacturing (AM) technology. However, the reasonable choice of process parameters for FDM is a significant task that directly affects the performance of the printed part. Therefore, it is necessary to investigate the influences of various process parameters on the quality characteristics of the components. The objectives of this study are to thoroughly review the current state of research that characterizes, estimates the effects of process parameters on mechanical properties, and summarizes the conclusions of existing works. In addition, some general issues of the presented research are summarized, and the need for future development is also emphasized. Finally, the research proposes several areas that deserve further study in this field.
Building More Resilient Culture Collections: A Call for Increased Deposits of Plant-Associated Bacteria
Authors: Broders Kirk , Aspin Andrew , Bailey Jordan , Chapman Toni , Portier Perrine , Weir Bevan S.
Published: March 2022

Biological collections preserve our past, while helping protect our future and increase future knowledge. Plant bacterial culture collections are our security for domestic and global biosecurity. This feature article will provide an introduction to the global position of plant bacterial collections. The role of collections in monitoring plant pathogenic bacteria will be explored through the presentation of five cases studies. These case studies demonstrate why culture collections were imperative for the outcome in each situation. We discuss what we believe should be the best practices to improve microbial preservation and accessioning rates, and why plant bacterial culture collections must increase deposits to be prepared for future emerging pathogens. This is not only the case for global culture collections, but on a much bigger scale, our future scientific successes, our biosecurity decisions and responses, and our knowledge are contingent upon preserving our valuable bacterial strains. It is hoped that once you read this article, you will see the need to deposit your strains in registered public collections and make a concerted effort to build better bacterial culture collections with us.
Engineered Salivary Peptides Reduce Enamel Demineralization Provoked by Cariogenic S. mutans Biofilm
Authors: Marin Lina Maria , Xiao Yizhi , Cury Jaime Aparecido , Siqueira Walter Luiz
Published: March 2022

Engineering of the acquired enamel pellicle using salivary peptides has been shown to be a promising anticaries strategy. However, the mechanisms by which these peptides protect teeth against tooth decay are not fully understood. In this study, we evaluated the effect of the engineered salivary peptides DR9-DR9 and DR9-RR14 on enamel demineralization in two experimental conditions: (1) adsorbed onto the enamel surface forming the AEP, and (2) forming the AEP combined with their use to treat the biofilms 2×/day, using a validated cariogenic Streptococcus mutans in vitro biofilm model. Biofilms were grown for 144 h on enamel slabs and then collected to determine the bacterial viability (CFU/biofilm) and biofilm mass (mg protein/biofilm), and to extract cellular/extracellular proteins, which were characterized by mass spectrometry. The culture medium was changed 2×/day to fresh medium, and pH (indicator of biofilm acidogenicity) and calcium concentration (indicator of demineralization) was determined in used medium. DR9-RR14 peptide significantly reduced enamel demineralization (p < 0.0001) in both experimental conditions. However, this peptide did not have a significant effect on biofilm biomass (p > 0.05) nor did it modulate the expression of cellular and extracellular bacterial proteins involved in biofilm cariogenicity. These findings suggest that DR9-RR14 may control caries development mainly by a physicochemical mechanism.
The Effects of Stevia Consumption on Gut Bacteria: Friend or Foe?
Authors: Kasti Arezina , Nikolaki Maroulla , Synodinou Kalliopi , Katsas Konstantinos , Petsis Konstantinos , Lambrinou Sophia , Pyrousis Ioannis , Triantafyllou Konstantinos
Published: March 2022

Stevia, a zero-calorie sugar substitute, is recognized as safe by the Food and Drug Administration (FDA) and the European Food Safety Authority (EFSA). In vitro and in vivo studies showed that stevia has antiglycemic action and antioxidant effects in adipose tissue and the vascular wall, reduces blood pressure levels and hepatic steatosis, stabilizes the atherosclerotic plaque, and ameliorates liver and kidney damage. The metabolism of steviol glycosides is dependent upon gut microbiota, which breaks down glycosides into steviol that can be absorbed by the host. In this review, we elucidated the effects of stevia’s consumption on the host’s gut microbiota. Due to the lack of randomized clinical trials in humans, we included in vitro using certain microbial strains and in vivo in laboratory animal studies. Results indicated that stevia consumption has a potential benefit on the microbiome’s alpha diversity. Alterations in the colonic microenvironment may depend on the amount and frequency of stevia intake, as well as on the simultaneous consumption of other dietary components. The anti-inflammatory properties of stevioside were confirmed in vitro by decreasing TNF-α, IL-1β, IL-6 synthesis and inhibiting of NF-κB transcription factor, and in vivo by inhibiting NF-κB and MAPK in laboratory animals.
Antiseptic Effects and Biosafety of a Controlled-Flow Electrolyzed Acid Solution Involve Electrochemical Properties, Rather than Free Radical Presence
Authors: Cabrera-Wrooman Alejandro , Ortega-Peña Silvestre , Salgado Rosa M. , Sandoval-Cuevas Belinda , Krötzsch Edgar
Published: March 2022

Electrolyzed acid solutions produced by different methods have antiseptic properties due to the presence of chlorine and reactive oxygen species. Our aim was to determine whether a controlled-flow electrolyzed acid solution (CFEAS) has the ability to improve wound healing due to its antiseptic and antibiofilm properties. First, we demonstrated in vitro that Gram-negative and Gram-positive bacteria were susceptible to CFEAS, and the effect was partially sustained for 24 h, evidencing antibiofilm activity (p < 0.05, CFEAS-treated vs. controls). The partial cytotoxicity of CFEAS was mainly observed in macrophages after 6 h of treatment; meanwhile, fibroblasts resisted short-lived free radicals (p < 0.05, CFEAS treated vs. controls), perhaps through redox-regulating mechanisms. In addition, we observed that a single 24 h CFEAS treatment of subacute and chronic human wounds diminished the CFU/g of tissue by ten times (p < 0.05, before vs. after) and removed the biofilm that was adhered to the wound, as we observed via histology from transversal sections of biopsies obtained before and after CFEAS treatment. In conclusion, the electrolyzed acid solution, produced by a novel method that involves a controlled flow, preserves the antiseptic and antibiofilm properties observed in other, similar formulas, with the advantage of being safe for eukaryotic cells; meanwhile, the antibiofilm activity is sustained for 24 h, both in vitro and in vivo.
Protein Assistants of Small Ribosomal Subunit Biogenesis in Bacteria
Authors: Maksimova Elena , Kravchenko Olesya , Korepanov Alexey , Stolboushkina Elena
Published: March 2022

Ribosome biogenesis is a fundamental and multistage process. The basic steps of ribosome assembly are the transcription, processing, folding, and modification of rRNA; the translation, folding, and modification of r-proteins; and consecutive binding of ribosomal proteins to rRNAs. Ribosome maturation is facilitated by biogenesis factors that include a broad spectrum of proteins: GTPases, RNA helicases, endonucleases, modification enzymes, molecular chaperones, etc. The ribosome assembly factors assist proper rRNA folding and protein–RNA interactions and may sense the checkpoints during the assembly to ensure correct order of this process. Inactivation of these factors is accompanied by severe growth phenotypes and accumulation of immature ribosomal subunits containing unprocessed rRNA, which reduces overall translation efficiency and causes translational errors. In this review, we focus on the structural and biochemical analysis of the 30S ribosomal subunit assembly factors RbfA, YjeQ (RsgA), Era, KsgA (RsmA), RimJ, RimM, RimP, and Hfq, which take part in the decoding-center folding.
Serological Evidence That SARS-CoV-2 Has Not Emerged in Deer in Germany or Austria during the COVID-19 Pandemic
Authors: Moreira-Soto Andres , Walzer Christian , Czirják Gábor Á. , Richter Martin H. , Marino Stephen F. , Posautz Annika , De Yebra Rodo Pau , McEwen Gayle K. , Drexler Jan Felix , Greenwood Alex D.
Published: March 2022

Spillover of severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) to North American white-tailed deer (Odocoileus virginianus) has been documented. However, it is unclear if this is a phenomenon specific to North American deer or is a broader problem. We evaluated pre and pandemic exposure of German and Austrian deer species using a SARS-CoV-2 pseudoneutralization assay. In stark contrast to North American white-tailed deer, we found no evidence of SARS-CoV-2 exposure.
The Role of Soil Microbial Diversity in the Conservation of Native Seed Bacterial Microbiomes
Authors: Chandel Ankush , Mann Ross , Kaur Jatinder , Norton Sally , Auer Desmond , Edwards Jacqueline , Spangenberg German , Sawbridge Timothy
Published: March 2022

Research into understanding the structure, composition and vertical transmission of crop seed microbiomes has intensified, although there is much less research into the seed microbiomes of crop wild relatives. Our previous study showed that the standard seed storage procedures (e.g., seed drying and storage temperature) can influence the seed microbiome of domesticated Glycine max. In this study, we characterized the seed microbiota of Glycine clandestina, a perennial wild relative of soybean (G. max (L.) Merr.) to expand our understanding about the effect of other storage procedures such as the periodic regeneration of seed stocks to bulk up seed numbers and secure viability on the seed microbiome of said seed. The G. clandestina microbiota was analysed from Generation 1 (G1) and Generation 2 (G2) seed and from mature plant organs grown in two different soil treatments T (treatment [native soil + potting mix]) and C (control [potting mix only]). Our dataset showed that soil microbiota had a strong influence on next generation seed microbiota, with an increased contribution of root microbiota by 90% and seed transmissibility by 36.3% in G2 (T) seed. Interestingly, the G2 seed microbiota primarily consisted of an initially low abundance of taxa present in G1 seed. Overall, our results indicate that seed regeneration can affect the seed microbiome composition and using native soil from the location of the source plant can enhance the conservation of the native seed microbiota.