bluuebunny/crossref_metadata_2025 huggingface dataset:
Lubricating Ability of Protic Ionic Liquids as Additives to a Biodegradable Oil for Aluminum-Steel Contact: Effect of Alkyl Chain Length and Propensity to Hydrogen Bonding
Authors: Guo Hong , Stoyanovich Brandon , Pang Junru , Iglesias Patricia
Published: August 2023

Although aluminum alloys are widely used in the automotive and aerospace industries due to their excellent strength-to-weight ratio and good corrosion resistance, the poor tribological performance and low compatibility of these materials with lubricant anti-wear and anti-friction additives in conventional mineral oils are major limitations. In addition, environmental awareness has increased the need for more environmentally friendly lubricants. Ionic Liquids (ILs) have exhibited significant potential as lubricants and lubricant additives. One of the more interesting properties of ILs is that they can form physically-adsorbed or chemically-reacted layers that reduce friction and wear of the surfaces in contact. Among ILs, Protic Ionic Liquids (PILs) have received more attention recently because of their simple and economic synthesis route. Furthermore, the anions and cations of PILs can be selected to be considered environmentally benign. In this article, the tribological behavior of a family of six PILs are studied as additives to a biodegradable oil (BO), under aluminum-steel contact. Al2024 disks slid against AISI52100 steel balls under a normal load of 3 N and a frequency of 5 Hz at room temperature and using a ball-on-flat reciprocating tribometer. PILs used in this study, were synthesized using two strong acids, with short and long hydrocarbon chains, and three weak bases with different propensities to hydrogen bonds. Results show that, although adding just 1 wt.% of any PIL to BO reduced friction and wear, the alkyl chain length influenced the lubricating ability of these ordered fluids. Wear mechanisms and surface interaction are discussed on the basis of 3D profilometry, SEM-EDX and RAMAN spectroscopy.
Carbon-Fiber-Recycling Strategies: A Secondary Waste Stream Used for PA6,6 Thermoplastic Composite Applications
Authors: Valente Marco , Sambucci Matteo , Rossitti Ilaria , Abruzzese Silvia , Sergi Claudia , Sarasini Fabrizio , Tirillò Jacopo
Published: August 2023

With a view to achieving sustainable development and a circular economy, this work focused on the possibility to valorize a secondary waste stream of recycled carbon fiber (rCF) to produce a 3D printing usable material with a PA6,6 polymer matrix. The reinforcing fibers implemented in the research are the result of a double-recovery action: starting with pyrolysis, long fibers are obtained, which are used to produce non-woven fabrics, and subsequently, fiber agglomerate wastes obtained from this last process are ground in a ball mill. The effect of different amounts of reinforcement at 5% and 10% by weight on the mechanical properties of 3D-printed thermoplastic composites was investigated. Although the recycled fraction was successfully integrated in the production of filaments for 3D printing and therefore in the production of specimens via the fused deposition modeling technique, the results showed that fibers did not improve the mechanical properties as expected, due to an unsuitable average size distribution and the presence of a predominant dusty fraction ascribed to the non-optimized ball milling process. PA6,6 + 10 wt.% rCF composites exhibited a tensile strength of 59.53 MPa and a tensile modulus of 2.24 GPa, which correspond to an improvement in mechanical behavior of 5% and 21% compared to the neat PA6,6 specimens, respectively. The printed composite specimens loaded with the lowest content of rCF provided the greatest improvement in strength (+9% over the neat sample). Next, a prediction of the “optimum” critical length of carbon fibers was proposed that could be used for future optimization of recycled fiber processing.
Optical Characterization of Materials for Precision Reference Spheres for Use with Structured Light Sensors
Authors: Zapico Pablo , Meana Victor , Cuesta Eduardo , Mateos Sabino
Published: August 2023

Traditionally, 3D digitizing sensors have been based on contact measurement. Given the disadvantages of this type of measurement, non-contact sensors such as structured light sensors have gained the attention of many sectors in recent years. The fact that their metrological performance is affected by the optical properties of the digitized material, together with the lack of standards, makes it necessary to develop characterization work to validate materials and calibration artifacts for the qualification and calibration of these sensors. This work compares and optically characterizes different materials and surface finishes of reference spheres used in the calibration of two structured light sensors with different fields of application, with the aim to determine the most suitable sphere material–sensor combination in each case. The contact measurement system of a CMM is used as a reference and, for the processing of the information from the sensors, the application of two different filters is analyzed. The results achieved point to sandblasted stainless steel spheres as the best choice for calibrating or qualifying these sensors, as well as for use as registration targets in digitizing. Tungsten carbide spheres and zirconium are unsuitable for this purpose.
Temperature Resistance Properties of Unidirectional Laminated Cf/SiC-Al Prepared by PIP and Vacuum Pressure Infiltration
Authors: Guan Tianru , Lu Le , Chen Zhaofeng , Yang Lixia
Published: August 2023

Material used for aero-engine fan blade requires excellent mechanical properties at high temperature (300 °C). Continuous carbon-fiber-reinforced silicon carbide ceramic matrix composites (Cf/SiC) are necessary candidates in this field, possessing low density, high strength, high modulus, and excellent high-temperature resistance. However, during the preparation process of Cf/SiC, there were inevitably residual pores and defects inside, resulting in insufficient compressive strength and reliability. The vacuum pressure melting infiltration process was used to infiltrate low melting point and high wettability aluminum alloys into the porous Cf/SiC composite material prepared by the precursor impregnation cracking process, repairing the residual pore defects inside the body. The porosity of porous Cf/SiC decreased from 49.65% to 5.1% after aluminum alloy repair and strengthening. The mechanical properties of Cf/SiC-Al composite materials strengthened by aluminum alloy repair after heat treatment were studied. The tensile strength of the as-prepared Cf/SiC-Al was 166 ± 10 MPa, which were degraded by 13~22% after heat treatment. The nonlinear sections of stress-displacement curve of as-treated samples were shorter than that of as-prepared sample. The hardness of aluminum alloy matrix after 300 °C 1 h heat treatment was 58 Hv, which was not obviously reduced compared with the sample without heat treatment. The vacuum infiltration of aluminum alloy is expected to have guiding significance for repairing and strengthening internal defects in ceramic matrix composites.
Variation Pattern of the Elastic Modulus of Concrete under Combined Humidity and Heat Conditions
Authors: Li Ping , Zhang Yanru , Duan Shiwei , Huang Ruiyuan , Gu Jiming
Published: August 2023

The coupling effect of moisture content and temperature on the elastic modulus of concrete is experimentally investigated. The elastic modulus of dry concrete exhibits a clear temperature-weakening effect, while the elastic modulus of wet concrete exhibits a water-strengthening effect at room temperature. Under humidity-heat conditions, the elastic modulus of wet concrete declines with the temperature rise. When the temperature is 20 °C, 200 °C, 400 °C, 520 °C, and 620 °C, the humidity–heat coupling factors of the elastic modulus change rate DI˙F with moisture content are 0.08, 0.07, 0.04, 0.01, and −0.03, respectively, and the declining rate increases with the rise of moisture content. The relation between the humidity-heat coupling factor DIF, moisture content, and temperature was established; The equivalent relation between the water-strengthening effect and the temperature-weakening effect of the elastic modulus was obtained. The temperature range of the strengthening effect and “apparent weakening effect” of water stored inside concrete before heating on elastic modulus was determined; The evolutionary mechanism of the competition between the microcrack expansion and healing of concrete under combined humidity and heat conditions was revealed.
Lower Carbon Footprint Concrete Using Recycled Carbon Fiber for Targeted Strength and Insulation
Authors: Patchen Andrew , Young Stephen , Goodbred Logan , Puplampu Stephen , Chawla Vivek , Penumadu Dayakar
Published: August 2023

The production of concrete leads to substantial carbon emissions (~8%) and includes reinforcing steel which is prone to corrosion and durability issues. Carbon-fiber-reinforced concrete is attractive for structural applications due to its light weight, high modulus, high strength, low density, and resistance to environmental degradation. Recycled/repurposed carbon fiber (rCF) is a promising alternative to traditional steel-fiber reinforcement for manufacturing lightweight and high-strength concrete. Additionally, rCF offers a sustainable, economical, and less energy-intensive solution for infrastructure applications. In this paper, structure–process–property relationships between the rheology of mix design, carbon fiber reinforcement type, thermal conductivity, and microstructural properties are investigated targeting strength and lighter weight using three types of concretes, namely, high-strength concrete, structural lightweight concrete, and ultra-lightweight concrete. The concrete mix designs were evaluated non-destructively using high-resolution X-ray computed tomography to investigate the microstructure of the voids and spatially correlate the porosity with the thermal conductivity properties and mechanical performance. Reinforced concrete structures with steel often suffer from durability issues due to corrosion. This paper presents advancements towards realizing concrete structures without steel reinforcement by providing required compression, adequate tension, flexural, and shear properties from recycled/repurposed carbon fibers and substantially reducing the carbon footprint for thermal and/or structural applications.
Magnetism and Electronic State of Iron Ions on the Surface and in the Core of TiO2 Nanoparticles
Authors: Yermakov Anatoly Ye. , Uimin Mikhail A. , Boukhvalov Danil W. , Minin Artem S. , Kleinerman Nadezhda M. , Naumov Sergey P. , Volegov Aleksey S. , Starichenko Denis V. , Borodin Kirill I. , Gaviko Vasily S. , Konev Sergey F. , Cherepanov Nikolay A.
Published: August 2023

In this paper, the electron and magnetic state of iron placed either on the surface or in the core of TiO2 nanoparticles were investigated using magnetometric methods, electron paramagnetic resonance (EPR) and Mössbauer spectroscopy. It was demonstrated that the EPR spectra of TiO2 samples with iron atoms localized both on the surface and in the core of specific features depending on the composition and size of the nanoparticles. Theoretical calculations using the density functional theory (DFT) method demonstrated that the localization of Fe atoms on the surface is characterized by a considerably larger set of atomic configurations as compared to that in the core of TiO2 nanoparticles. Mössbauer spectra of the samples doped with Fe atoms both on the surface and in the core can be described quite satisfactorily using two and three doublets with different quadrupole splitting, respectively. This probably demonstrates that the Fe atoms on particle surface and in the bulk are in different unlike local surroundings. All iron ions, both on the surface and in the core, were found to be in the Fe3+ high-spin state.
Achievable Minimally-Contrastive Counterfactual Explanations
Authors: Barzekar Hosein , McRoy Susan
Published: August 2023

Decision support systems based on machine learning models should be able to help users identify opportunities and threats. Popular model-agnostic explanation models can identify factors that support various predictions, answering questions such as “What factors affect sales?” or “Why did sales decline?”, but do not highlight what a person should or could do to get a more desirable outcome. Counterfactual explanation approaches address intervention, and some even consider feasibility, but none consider their suitability for real-time applications, such as question answering. Here, we address this gap by introducing a novel model-agnostic method that provides specific, feasible changes that would impact the outcomes of a complex Black Box AI model for a given instance and assess its real-world utility by measuring its real-time performance and ability to find achievable changes. The method uses the instance of concern to generate high-precision explanations and then applies a secondary method to find achievable minimally-contrastive counterfactual explanations (AMCC) while limiting the search to modifications that satisfy domain-specific constraints. Using a widely recognized dataset, we evaluated the classification task to ascertain the frequency and time required to identify successful counterfactuals. For a 90% accurate classifier, our algorithm identified AMCC explanations in 47% of cases (38 of 81), with an average discovery time of 80 ms. These findings verify the algorithm’s efficiency in swiftly producing AMCC explanations, suitable for real-time systems. The AMCC method enhances the transparency of Black Box AI models, aiding individuals in evaluating remedial strategies or assessing potential outcomes.
Model-Based Optimization Approach for PID Control of Pitch–Roll UAV Orientation
Authors: Arrieta Orlando , Campos Daniel , Rico-Azagra Javier , Gil-Martínez Montserrat , Rojas José D. , Vilanova Ramon
Published: August 2023

This study focuses on the modeling and control optimization of the pitch–roll angles orientation in a quad-rotor UAV (unmanned aerial vehicle) drone system. To address the control challenge, PID (proportional–integral–derivative) controllers are used, which have been tuned through a model-based optimization approach. A non-linear model of the system is obtained and further validated experimentally. The model is implemented in Simulink to conduct model-based optimization. The controller design uses an IMC (internal model control) model-based approach to establish the initial parameters for a PID controller. In the subsequent design phase, a multiobjective approach is taken, incorporating weighted cost functions that account for IAE (integral absolute error) and ITAE (integral of time-weighted absolute error) forms, along with battery usage. The outcomes of this design are showcased through simulations and real-world platform testing.
Cycle Existence for All Edges in Folded Hypercubes under Scope Faults
Authors: Kuo Che-Nan , Cheng Yu-Huei
Published: August 2023

The reliability of large-scale networks can be compromised by various factors such as natural disasters, human-induced incidents such as hacker attacks, bomb attacks, or even meteorite impacts, which can lead to failures in scope of processors or links. Therefore, ensuring fault tolerance in the interconnection network is vital to maintaining system reliability. The n-dimensional folded hypercube network structure, denoted as FQn, is constructed by adding an edge between every pair of vertices with complementary addresses from an n-dimensional hypercube, Qn. Notably, FQn exhibits distinct characteristics based on the dimensionality: it is bipartite for odd integers n≥3 and non-bipartite for even integers n≥2. Recently, in terms of the issue of how FQn performs in communication under regional or widespread destruction, we mentioned that in FQn, even when a pair of adjacent vertices encounter errors, any fault-free edge can still be embedded in cycles of various lengths. Additionally, even when the smallest communication ring experiences errors, it is still possible to embed cycles of any length. The smallest communication ring in FQn is observed to be the four-cycle ring. In order to further investigate the communication capabilities of FQn, we further discuss whether every fault-free edge will still be a part of every communication ring with different lengths when the smallest communication ring is compromised in FQn. In this study, we consider a fault-free edge e=(u,v) and F4={f1, f2,f3, f4} as the set of faulty extreme vertices for any four cycles in FQn. Our research focuses on investigating the cycle-embedding properties in FQn−F4, where the fault-free edges play a significant role. The following properties are demonstrated: (1) For n≥4 in FQn−F4, every even length cycle with a length ranging from 4 to 2n−4 contains a fault-free edge e; (2) For every even n≥4 in FQn−F4, every odd length cycle with a length ranging from n+1 to 2n−5 contains a fault-free edge e. These findings provide insights into the cycle-embedding capabilities of FQn, specifically in the context of fault tolerance when considering certain sets of faulty vertices.
New (3+1)-Dimensional Kadomtsev–Petviashvili–Sawada– Kotera–Ramani Equation: Multiple-Soliton and Lump Solutions
Authors: Wazwaz Abdul-Majid , Abu Hammad Ma’mon , Al-Ghamdi Ali O. , Alshehri Mansoor H. , El-Tantawy Samir A.
Published: August 2023

In this investigation, a novel (3+1)-dimensional Lax integrable Kadomtsev–Petviashvili–Sawada–Kotera–Ramani equation is constructed and analyzed analytically. The Painlevé integrability for the mentioned model is examined. The bilinear form is applied for investigating multiple-soliton solutions. Moreover, we employ the positive quadratic function method to create a class of lump solutions using distinct parameters values. The current study serves as a guide to explain many nonlinear phenomena that arise in numerous scientific domains, such as fluid mechanics; physics of plasmas, oceans, and seas; and so on.
Deep Convolutional and Recurrent Neural-Network-Based Optimal Decoding for RIS-Assisted MIMO Communication
Authors: Rahman Md Habibur , Sejan Mohammad Abrar Shakil , Aziz Md Abdul , Kim Dong-Sun , You Young-Hwan , Song Hyoung-Kyu
Published: August 2023

The reconfigurable intelligent surface (RIS) is one of the most innovative and revolutionary technologies for increasing the effectiveness of wireless systems. Deep learning (DL) is a promising method that can enhance system efficacy using powerful tools in RIS-based environments. However, the lack of extensive training of the DL model results in the reduced prediction of feature information and performance failure. Hence, to address the issues, in this paper, a combined DL-based optimal decoding model is proposed to improve the transmission error rate and enhance the overall efficiency of the RIS-assisted multiple-input multiple-output communication system. The proposed DL model is comprised of a 1-dimensional convolutional neural network (1-D CNN) and a gated recurrent unit (GRU) module where the 1-D CNN model is employed for the extraction of features from the received signal with further process over the configuration of different layers. Thereafter, the processed data are used by the GRU module for successively retrieving the transmission signal with a minimal error rate and accelerating the convergence rate. It is initially trained offline using created OFDM data sets, after which it is used online to track the channel and extract the transmitted data. The simulation results show that the proposed network performs better than the other technique that was previously used in terms of bit error rate and symbol error rate. The outcomes of the model demonstrate the suitability of the proposed model for use with the next-generation wireless communication system.
Drug Delivery through Epidermal Tissue Cells by Functionalized Biosilica from Diatom Microalgae
Authors: Vona Danilo , Flemma Annarita , Piccapane Francesca , Cotugno Pietro , Cicco Stefania Roberta , Armenise Vincenza , Vicente-Garcia Cesar , Giangregorio Maria Michela , Procino Giuseppe , Ragni Roberta
Published: August 2023

Diatom microalgae are a natural source of fossil biosilica shells, namely the diatomaceous earth (DE), abundantly available at low cost. High surface area, mesoporosity and biocompatibility, as well as the availability of a variety of approaches for surface chemical modification, make DE highly profitable as a nanostructured material for drug delivery applications. Despite this, the studies reported so far in the literature are generally limited to the development of biohybrid systems for drug delivery by oral or parenteral administration. Here we demonstrate the suitability of diatomaceous earth properly functionalized on the surface with n-octyl chains as an efficient system for local drug delivery to skin tissues. Naproxen was selected as a non-steroidal anti-inflammatory model drug for experiments performed both in vitro by immersion of the drug-loaded DE in an artificial sweat solution and, for the first time, by trans-epidermal drug permeation through a 3D-organotypic tissue that better mimics the in vivo permeation mechanism of drugs in human skin tissues. Octyl chains were demonstrated to both favour the DE adhesion onto porcine skin tissues and to control the gradual release and the trans-epidermal permeation of Naproxen within 24 h of the beginning of experiments. The evidence of the viability of human epithelial cells after permeation of the drug released from diatomaceous earth, also confirmed the biocompatibility with human skin of both Naproxen and mesoporous biosilica from diatom microalgae, disclosing promising applications of these drug-delivery systems for therapies of skin diseases.
Review of Marine Cyanobacteria and the Aspects Related to Their Roles: Chemical, Biological Properties, Nitrogen Fixation and Climate Change
Authors: El-Seedi Hesham R. , El-Mallah Mohamed F. , Yosri Nermeen , Alajlani Muaaz , Zhao Chao , Mehmood Muhammad A. , Du Ming , Ullah Hammad , Daglia Maria , Guo Zhiming , Khalifa Shaden A. M. , Shou Qiyang
Published: August 2023

Marine cyanobacteria are an ancient group of photosynthetic microbes dating back to 3.5 million years ago. They are prolific producers of bioactive secondary metabolites. Over millions of years, natural selection has optimized their metabolites to possess activities impacting various biological targets. This paper discusses the historical and existential records of cyanobacteria, and their role in understanding the evolution of marine cyanobacteria through the ages. Recent advancements have focused on isolating and screening bioactive compounds and their respective medicinal properties, and we also discuss chemical property space and clinical trials, where compounds with potential pharmacological effects, such as cytotoxicity, anticancer, and antiparasitic properties, are highlighted. The data have shown that about 43% of the compounds investigated have cytotoxic effects, and around 8% have anti-trypanosome activity. We discussed the role of different marine cyanobacteria groups in fixing nitrogen percentages on Earth and their outcomes in fish productivity by entering food webs and enhancing productivity in different agricultural and ecological fields. The role of marine cyanobacteria in the carbon cycle and their outcomes in improving the efficiency of photosynthetic CO2 fixation in the chloroplasts of crop plants, thus enhancing the crop plant’s yield, was highlighted. Ultimately, climate changes have a significant impact on marine cyanobacteria where the temperature rises, and CO2 improves the cyanobacterial nitrogen fixation.
Low-Level Laser Therapy for the Treatment of Oral Mucositis Induced by Hematopoietic Stem Cell Transplantation: A Systematic Review with Meta-Analysis
Authors: Franco Rocco , Lupi Ettore , Iacomino Enzo , Galeotti Angela , Capogreco Mario , Santos João Miguel Marques , D’Amario Maurizio
Published: August 2023

Oral mucositis is a common and debilitating side effect induced by stem cell transplantation that is experienced by cancer patients undergoing chemotherapy or radiation therapy. This condition involves inflammation and ulceration of the oral mucosa, leading to pain, difficulty with eating and speaking, and an increased risk of infections. Mucositis not only compromises the quality of life for cancer patients, but also affects treatment outcomes and may necessitate dose reductions or treatment delays. This scientific article provides a comprehensive overview of mucositis. The purpose of this literature review with a meta-analysis is to evaluate the efficacy of laser therapy in treating post-transplant mucositis. Materials and methods: A search of the literature from 3 May 2023 was carried out on three online databases, PubMed, Scopus, and Web of Science. Only studies that treated patients with laser therapy were considered; only studies with the placebo-treated control group were considered. Review Manager version 5.2.8 (Cochrane Collaboration) was used for the pooled analysis. We measured the std. mean difference between the two groups (laser and placebo). Results: There were 230 papers included in this review. Two hundred twenty-seven were excluded. Furthermore, a manual search was performed. After the search phase, three articles were considered in the study. The overall effect showed differences in the degree of mucositis in the laser-treated patients compared with the placebo group. The meta-analysis shows a reduction in the degree of mucositis in the patients treated with laser therapy (std. mean difference −1.34 [−1.98; −0.98]; C.I. 95%). Conclusions: The application of laser therapy results in decreased severity of oral mucositis from radiation and chemotherapy. Our study shows that the application of low-level laser therapy in the treatment of transplant mucositis has excellent efficacy in relieving the symptoms and severity of mucositis.
Granulomatous Mastitis Occurring during Pregnancy: A Case Report
Authors: Yoshino Ryusei , Yoshida Nana , Ito Akane , Ujiie Nanami , Nakatsubo Masaki , Hayashi Manami , Kitada Masahiro
Published: August 2023

Background and Objectives: Granulomatous mastitis is a benign disease with a clinical presentation similar to that of breast cancer, and is most commonly observed in women of childbearing age. Although it has been suggested that autoimmune diseases are involved in its pathogenesis, no specific treatments have been established. The occurrence of this disease during pregnancy has rarely been reported. We presented the case of a 37-year-old woman who complained of left breast induration at 24 weeks’ gestation. Materials and Methods: She was pregnant and manifested a dichorionic, diamniotic placenta. At 24 weeks of gestation, the patient experienced a sensation of hardness in her left breast. Mastitis was suspected, and she was treated with cephem antibiotics. Simultaneously, she was diagnosed with erythema nodosum in the extremities. As her symptoms did not improve, an incisional drainage was performed. Bacterial cultures were obtained at 31 weeks of gestation, and Corynebacterium kroppenstedtii was detected. Results: An elective cesarean section was performed at 37 weeks of gestation, and the baby was delivered safely. After delivery, a needle biopsy was performed, and the patient was diagnosed with granulomatous mastitis. She was completely cured with prednisolone after weaning. In this case, the patient’s condition was maintained through incision and drainage, as well as antibiotic, anti-inflammatory, and analgesic drugs during pregnancy. This approach was chosen, taking into consideration the potential side effects of steroids. Conclusions: This case suggests that incisional drainage and antibiotic therapy, as well as steroids and surgery, may be considered in the treatment of granulomatous mastitis occurring during pregnancy. This may also be true for management during delivery. After delivery, breastfeeding and steroidal therapy proved to be effective in treating the condition.
Influence of Quenching and Subsequent Artificial Aging on Tensile Strength of Laser-Welded Joints of Al–Cu–Li Alloy
Authors: Malikov Alexandr , Karpov Evgeniy , Kuper Konstantin , Shmakov Alexandr
Published: August 2023

The research aim was to optimize post-weld heat-treatment (PWHT) modes for a laser-welded joint of the Al–Cu–Li alloy and improve their respective strength properties. As a result, the ultimate tensile strength, yield point, and elongation of the joint were enhanced up to 95%, 94%, and 38%, respectively, of those inherent in the base metal. Before and after PWHT, both microstructures and phase compositions have been examined by optical and scanning electron microscopy, as well as synchrotron X-ray diffractometry. In the as-welded metal, the α-Al and T1(Al2CuLi) phases were found, along with the θ′(Al2Cu) and S′(Al2CuMg) phases localized at the grain boundaries, significantly reducing the mechanical properties of the joint. Upon quenching, the agglomerates dissolved at the grain boundaries, the solid solution was homogenized, and both Guinier–Preston zones and precipitates of the intermediate metastable θ″ phase were formed. After subsequent optimal artificial aging, the (predominant) hardening θ′ and (partial) T1(Al2CuLi) phases were observed in the weld metal, which contributed to the improvement of the strength properties of the joint.
Effect of Y on Arc Breaking Behavior of Platinum–Iridium Alloy Contact Materials at Different Voltages
Authors: Wang Saibei , Sun Yong , Chen Song , Wang Song , Li Aikun , Duan Yonghua , Yang Youcai , Peng Mingjun , Xie Ming , Li Bo
Published: August 2023

The Pt–Ir alloy is an important electrical contact material in the aerospace field, and its electrical contact performance directly affects the reliability and stability of the circuit system. In order to elucidate the effect of Y on the breaking arc behavior of Pt–Ir alloys at different voltages, Pt-10Ir-1Y and Pt-25Ir-1Y alloys were prepared using melting and thermal processing, and the electrical contact tests were carried out at DC 15 A 12 V, 24 V, and 36 V. When comparing the results of Pt-10Ir and Pt-25Ir electrical contact tests, they showed that Y doping provided a tendency to concentrate individual arc erosion regions. Meanwhile, the comparative study showed that the addition of Y could inhibit the tendency of the Pt–Ir arc time to increase with voltage. At 36 V, the overall arc time of Pt–Ir–Y was significantly lower than that of Pt–Ir, and the fluctuation in arc time and arc energy was reduced. In addition, Y reduced the welding force of Pt–Ir alloys at 12 V, while Y improved the stability of the welding force of Pt–Ir alloys at 24 V. It could be seen that Y was favorable to improving the arc erosion resistance of the Pt–Ir alloy under certain conditions. The contact resistance analysis showed that there was an obvious partitioning phenomenon in the contact resistance of Pt–Ir alloys, and Y changed in this phenomenon at a certain voltage range. In addition, the material transfer direction of the Pt–Ir alloy was from the anode to the cathode, which was not affected by the voltage change, while the addition of Y changed the material transfer direction from the cathode to the anode, which was likely caused by the change from the metal-phase arc dominance to gas-phase arc dominance.
Reproducible Quantification of the Microstructure of Complex Quenched and Quenched and Tempered Steels Using Modern Methods of Machine Learning
Authors: Bachmann Björn-Ivo , Müller Martin , Britz Dominik , Staudt Thorsten , Mücklich Frank
Published: August 2023

Current conventional methods of evaluating microstructures are characterized by a high degree of subjectivity and a lack of reproducibility. Modern machine learning (ML) approaches have already shown great potential in overcoming these challenges. Once trained with representative data in combination with objective ground truth, the ML model is able to perform a task properly in a reproducible and automated manner. However, in highly complex use cases, it is often not possible to create a definite ground truth. This study addresses this problem using the underlying showcase of microstructures of highly complex quenched and quenched and tempered (Q/QT) steels. A patch-wise classification approach combined with a sliding window technique provides a solution for segmenting entire microphotographs where pixel-wise segmentation is not applicable since it is hardly feasible to create reproducible training masks. Using correlative microscopy, consisting of light optical microscope (LOM) and scanning electron microscope (SEM) micrographs, as well as corresponding data from electron backscatter diffraction (EBSD), a training dataset of reference states that covers a wide range of microstructures was acquired in order to train accurate and robust ML models in order to classify LOM or SEM images. Despite the enormous complexity associated with the steels treated here, classification accuracies of 88.8% in the case of LOM images and 93.7% for high-resolution SEM images were achieved. These high accuracies are close to super-human performance, especially in consideration of the reproducibility of the automated ML approaches compared to conventional methods based on subjective evaluations through experts.
Reduced Plasma Guanylin Levels Following Enterotoxigenic Escherichia coli-Induced Diarrhea
Authors: Brønstad Ingeborg , von Volkmann Hilde Løland , Sakkestad Sunniva Todnem , Steinsland Hans , Hanevik Kurt
Published: August 2023

The intestinal peptide hormones guanylin (GN) and uroguanylin (UGN) interact with the epithelial cell receptor guanylate cyclase C to regulate fluid homeostasis. Some enterotoxigenic Escherichia coli (ETEC) produce heat-stable enterotoxin (ST), which induces diarrhea by mimicking GN and UGN. Plasma concentrations of prohormones of GN (proGN) and UGN (proUGN) are reportedly decreased during chronic diarrheal diseases. Here we investigate whether prohormone concentrations also drop during acute diarrhea caused by ST-producing ETEC strains TW10722 and TW11681. Twenty-one volunteers were experimentally infected with ETEC. Blood (n = 21) and urine (n = 9) specimens were obtained immediately before and 1, 2, 3, and 7 days after ETEC ingestion. Concentrations of proGN and proUGN were measured by ELISA. Urine electrolyte concentrations were measured by photometry and mass spectrometry. Ten volunteers developed diarrhea (D group), and eleven did not (ND group). In the D group, plasma proGN, but not proUGN, concentrations were substantially reduced on days 2 and 3, coinciding with one day after diarrhea onset. No changes were seen in the ND group. ETEC diarrhea also seemed to affect diuresis, the zinc/creatinine ratio, and sodium and chloride secretion levels in urine. ETEC-induced diarrhea causes a reduction in plasma proGN and could potentially be a useful marker for intestinal isotonic fluid loss.
Monocyte-Derived Chicken Macrophages Exposed to Eimeria tenella Sporozoites Display Reduced Susceptibility to Invasion by Toxoplasma gondii Tachyzoite
Authors: Zhang Runhui , Zheng Wanpeng , Daugschies Arwid , Bangoura Berit
Published: August 2023

Both Eimeria tenella and Toxoplasma gondii are common apicomplexan parasites in chickens. Host cell invasion by both protozoans includes gliding motility, host cell attachment and active penetration. Chicken macrophages as phagocytic cells participate in the innate host immune response against these two parasites. In this study, primary chicken monocyte-derived macrophages (MM) were infected with both pathogens to investigate mutual and host–parasite interactions. MM cultures were assigned to groups that were infected with E. tenella, T. gondii or both. In co-infected cultures, MM were first exposed to E. tenella sporozoites for 2 h. Afterwards, T. gondii tachyzoite infection was performed. Live-cell imaging was carried out to observe cell invasion and survival of T. gondii by single parasite tracking over a period of 20 h post infection (hpi). Quantitative analysis for parasite replication was performed by real-time quantitative PCR (qPCR) at 2, 6, 12 and 24 hpi. Overall, the ability of T. gondii to penetrate the cell membrane of the potential host cell was reduced, although high motility was displayed. We found that T. gondii tachyzoites adhered for more than 4 h to macrophages during early co-infection. qPCR results confirmed that significantly less T. gondii entered in E. tenella-activated MM at 2 hpi, and a reduced proportion of intracellular T. gondii survived and replicated in these cells at 24 hpi. We conclude that E. tenella modulates host cell responses to another apicomplexan agent, T. gondii, reducing active invasion and multiplication in chicken primary macrophages.
Different Responses of Bacteria and Archaea to Environmental Variables in Brines of the Mahai Potash Mine, Qinghai-Tibet Plateau
Authors: Xie Linglu , Yu Shan , Lu Xindi , Liu Siwei , Tang Yukai , Lu Hailong
Published: August 2023

Salt mines feature both autochthonous and allochthonous microbial communities introduced by industrialization. It is important to generate the information on the diversity of the microbial communities present in the salt mines and how they are shaped by the environment representing ecological diversification. Brine from Mahai potash mine (Qianghai, China), an extreme hypersaline environment, is used to produce potash salts for hundreds of millions of people. However, halophiles preserved in this niche during deposition are still unknown. In this study, using high-throughput 16S rRNA gene amplicon sequencing and estimation of physicochemical variables, we examined brine samples collected from locations with the gradient of industrial activity intensity and discrete hydrochemical compositions in the Mahai potash mine. Our findings revealed a highly diverse bacterial community, mainly composed of Pseudomonadota in the hypersaline brines from the industrial area, whereas in the natural brine collected from the upstream Mahai salt lake, most of the 16S rRNA gene reads were assigned to Bacteroidota. Halobacteria and halophilic methanogens dominated archaeal populations. Furthermore, we discovered that in the Mahai potash mining area, bacterial communities tended to respond to anthropogenic influences. In contrast, archaeal diversity and compositions were primarily shaped by the chemical properties of the hypersaline brines. Conspicuously, distinct methanogenic communities were discovered in sets of samples with varying ionic compositions, indicating their strong sensitivity to the brine hydrochemical alterations. Our findings provide the first taxonomic snapshot of microbial communities from the Mahai potash mine and reveal the different responses of bacteria and archaea to environmental variations in this high-altitude aquatic ecosystem.
High Levels of Antibiotic Resistance in MDR-Strong Biofilm-Forming Salmonella Typhimurium ST34 in Southern China
Authors: Gao Yuan , Chen Kaifeng , Lin Runshan , Xu Xuebin , Xu Fengxiang , Lin Qijie , Hu Yaping , Zhang Hongxia , Zhang Jianmin , Liao Ming , Qu Xiaoyun
Published: August 2023

Salmonella enterica subsp. enterica serovar Typhimurium (S. typhimurium) is an important zoonotic pathogen with important public health significance. To understand S. typhimurium’s epidemiological characteristics in China, multi-locus sequence typing, biofilm-forming ability, antimicrobial susceptibility testing, and resistant genes of isolates from different regions and sources (human, food) were investigated. Among them, ST34 accounted for 82.4% (243/295), with ST19 ranking second (15.9%; 47/295). ST34 exhibited higher resistance levels than ST19 (p < 0.05). All colistin, carbapenem, and ciprofloxacin-resistant strains were ST34, as were most cephalosporin-resistant strains (88.9%; 32/36). Overall, 91.4% (222/243) ST34 isolates were shown to have multidrug resistance (MDR), while 53.2% (25/47) ST19 isolates were (p < 0.05). Notably, 97.8% (45/46) of the MDR-ACSSuT (resistance to Ampicillin, Chloramphenicol, Streptomycin, Sulfamethoxazole, and Tetracycline) isolates were ST34, among which 69.6% (32/46) of ST34 isolates were of human origin, while 30.4% (14/46) were derived from food (p < 0.05). Moreover, 88.48% (215/243) ST34 showed moderate to strong biofilm-forming ability compared with 10.9% (5/46) ST19 isolates (p < 0.01). This study revealed the emergence of high-level antibiotic resistance S. typhimurium ST34 with strong biofilm-forming ability, posing concerns for public health safety.
π-Conjugated Polymer Nanoparticles from Design, Synthesis to Biomedical Applications: Sensing, Imaging, and Therapy
Authors: Elgiddawy Nada , Elnagar Noha , Korri-Youssoufi Hafsa , Yassar Abderrahim
Published: August 2023

In the past decade, π-conjugated polymer nanoparticles (CPNs) have been considered as promising nanomaterials for biomedical applications, and are widely used as probe materials for bioimaging and drug delivery. Due to their distinctive photophysical and physicochemical characteristics, good compatibility, and ease of functionalization, CPNs are gaining popularity and being used in more and more cutting-edge biomedical sectors. Common synthetic techniques can be used to synthesize CPNs with adjustable particle size and dispersion. More importantly, the recent development of CPNs for sensing and imaging applications has rendered them as a promising device for use in healthcare. This review provides a synopsis of the preparation and functionalization of CPNs and summarizes the recent advancements of CPNs for biomedical applications. In particular, we discuss their major role in bioimaging, therapeutics, fluorescence, and electrochemical sensing. As a conclusion, we highlight the challenges and future perspectives of biomedical applications of CPNs.
Polyoxometalate-Stabilized Silver Nanoparticles and Hybrid Electrode Assembly Using Activated Carbon
Authors: Goberna-Ferrón Sara , Cots Laia , Perxés Perich Marta , Zhu Jun-Jie , Gómez-Romero Pedro
Published: August 2023

The intersection between the field of hybrid materials and that of electrochemistry is a quickly expanding area. Hybrid combinations usually consist of two constituents, but new routes toward more complex and versatile electroactive hybrid designs are quickly emerging. The objective of the present work is to explore novel triple hybrid material integrating polyoxometalates (POMs), silver nanoparticles (Ag0 NPs), and activated carbon (AC) and to demonstrate its use as a hybrid electrode in a symmetric supercapacitor. The tri-component nanohybrid (AC/POM-Ag0 NPs) was fabricated through the combination of AC with pre-synthesized ∼27 nm POM-protected Ag0 NPs (POM-Ag0 NPs). The POM-Ag0 NPs were prepared using a green electrochemical method and characterized via UV-vis and IR spectroscopy, electron microscopy, dynamic light scattering (DLS), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and cyclic voltammetry (CV). Afterward, the AC/POM-Ag0 NPs ternary nanocomposite material was constructed and characterized. The electrochemical behavior of AC/POM-Ag0 NPs’ modified electrodes reveal that the nanomaterial is electroactive and exhibits a moderately higher specific capacitance (81 F/g after 20 cycles) than bare AC electrodes (75 F/g) in a symmetrical supercapacitor configuration in the voltage range 0 to 0.75 V and 20 mV/s, demonstrating the potential use of this type of tri-component nanohybrid for electrochemical applications.
Thermally Conductive and Electrically Insulating Epoxy Composites Filled with Network-like Alumina In Situ Coated Graphene
Authors: Lv Ruicong , Guo Haichang , Kang Lei , Bashir Akbar , Ren Liucheng , Niu Hongyu , Bai Shulin
Published: August 2023

With the rapid development of the electronics industry, there is a growing demand for packaging materials that possess both high thermal conductivity (TC) and low electrical conductivity (EC). However, traditional insulating fillers such as boron nitride, aluminum nitride, and alumina (Al2O3) have relatively low intrinsic TC. When graphene, which exhibits both superhigh TC and EC, is used as a filler to fill epoxy resin, the TC of blends can be much higher than that of blends containing more traditional fillers. However, the high EC of graphene limits its application in cases where electrical insulation is required. To address this challenge, a method for coating graphene sheets with an in situ grown Al2O3 layer has been proposed for the fabrication of epoxy-based composites with both high TC and low EC. In the presence of a cationic surfactant, a dense Al2O3 layer with a network structure can be formed on the surface of graphene sheets. When the total content of Al2O3 and graphene mixed filler reached 30 wt%, the TC of the epoxy composite reached 0.97 W m−1 K−1, while the EC remained above 1011 Ω·cm. Finite element simulations accurately predicted TC and EC values in accordance with experimental results. This material, with its combination of high TC and good insulation properties, exhibits excellent potential for microelectronic packaging applications.
An Aqueous Process for Preparing Flexible Transparent Electrodes Using Non-Oxidized Graphene/Single-Walled Carbon Nanotube Hybrid Solution
Authors: Oh Min Jae , Son Gi-Cheol , Kim Minkook , Jeon Junyoung , Kim Yong Hyun , Son Myungwoo
Published: August 2023

In this study, we prepared flexible and transparent hybrid electrodes based on an aqueous solution of non-oxidized graphene and single-walled carbon nanotubes. We used a simple halogen intercalation method to obtain high-quality graphene flakes without a redox process and prepared hybrid films using aqueous solutions of graphene, single-walled carbon nanotubes, and sodium dodecyl sulfate surfactant. The hybrid films showed excellent electrode properties, such as an optical transmittance of ≥90%, a sheet resistance of ~3.5 kΩ/sq., a flexibility of up to ε = 3.6% ((R) = 1.4 mm), and a high mechanical stability, even after 103 bending cycles at ε = 2.0% ((R) = 2.5 mm). Using the hybrid electrodes, thin-film transistors (TFTs) were fabricated, which exhibited an electron mobility of ~6.7 cm2 V−1 s−1, a current on-off ratio of ~1.04 × 107, and a subthreshold voltage of ~0.122 V/decade. These electrical properties are comparable with those of TFTs fabricated using Al electrodes. This suggests the possibility of customizing flexible transparent electrodes within a carbon nanomaterial system.