bluuebunny/crossref_metadata_2025 huggingface dataset:
Poiseuille-Type Approximations for Axisymmetric Flow in a Thin Tube with Thin Stiff Elastic Wall
Authors: Kaulakytė Kristina , Kozulinas Nikolajus , Panasenko Grigory , Pileckas Konstantinas , Šumskas Vytenis
Published: April 2023

An asymptotic ansatz for the solution of the axisymmetric problem of interaction between a thin cylindrical elastic tube and a viscous fluid filling the thin interior of the elastic tube was recently introduced and justified by G. Panasenko and R. Stavre. The thickness of the elastic medium (ε) and that of the fluid domain (ε1) are small parameters with ε<<ε1<<1, while the scale of the longitudinal characteristic size is of order one. At the same time, the magnitude of the stiffness and density of the elastic tube may be large or finite parameters with respect to the viscosity and density of the fluid when the characteristic time is of order one. This ansatz can be considered as a Poiseuille-type solution for the fluid–structure interaction problem. Its substitution to the Stokes fluid–elastic wall coupled problem generates a one-dimensional model. We present a numerical experiment comparing this model with the solution of the full-dimensional fluid–structure interaction problem.
Entropy-Optimized Fault Diagnosis Based on Unsupervised Domain Adaptation
Authors: Liu Fuqiang , Chen Yandan , Deng Wenlong , Zhou Mingliang
Published: April 2023

In practice, the cross-domain transfer of data distribution and the sample imbalance of fault status are inevitable, but one or both are often ignored, which restricts the adaptability and classification accuracy of the generated fault diagnosis (FD) model. Accordingly, an entropy-optimized method is proposed in this paper based on an unsupervised domain-adaptive technique to enhance FD model training. For the training, pseudosamples and labels corresponding to the target samples are generated through data augmentation and self-training strategies to diminish the distribution discrepancy between the source and target domains. Meanwhile, an adaptive conditional entropy loss function is developed to improve the data quality of the semisupervised learning, with which reliable samples are generated for the training. According to the experiment results, compared with other state-of-the-art algorithms, our method can achieve significant accuracy improvement in rolling bearing FD. Typically, the accuracy improvement compared with the baseline Convolutional Neural Network (CNN) is achieved by over 13.23%.
Computation of the Distribution of the Sum of Independent Negative Binomial Random Variables
Authors: Girondot Marc , Barry Jon
Published: April 2023

The distribution of the sum of negative binomial random variables has a special role in insurance mathematics, actuarial sciences, and ecology. Two methods to estimate this distribution have been published: a finite-sum exact expression and a series expression by convolution. We compare both methods, as well as a new normalized saddlepoint approximation, and normal and single distribution negative binomial approximations. We show that the exact series expression used lots of memory when the number of random variables was high (>7). The normalized saddlepoint approximation gives an output with a high relative error (around 3–5%), which can be a problem in some situations. The convolution method is a good compromise for applied practitioners, considering the amount of memory used, the computing time, and the precision of the estimates. However, a simplistic implementation of the algorithm could produce incorrect results due to the non-monotony of the convergence rate. The tolerance limit must be chosen depending on the expected magnitude order of the estimate, for which we used the answer generated by the saddlepoint approximation. Finally, the normal and negative binomial approximations should not be used, as they produced outputs with a very low accuracy.
Impact of CPAP Therapy Adherence on Global Cognition in Patients with Moderate to Severe Obstructive Sleep Apnea: A One-Year Follow-Up
Authors: Velescu Diana Raluca , Marc Monica Steluta , Pescaru Camelia Corina , Traila Daniel , Vaștag Emanuela , Papava Ion , Motofelea Alexandru Catalin , Ciuca Ioana Mihaiela , Manolescu Diana , Oancea Cristian
Published: April 2023

Background: Obstructive sleep apnea increases (OSA) cognitive impairment risk. The objective of this study was to determine the impact of continuous positive airway pressure (CPAP) adherence on global cognition using the Montreal Cognitive Assessment questionnaire (MoCA). Materials and Methods: Thirty-four new patients diagnosed with moderate or severe OSA (apnea-hypopnea index AHI ≥ 15 events/h) from the CPAP group were compared with thirty-one moderate to severe OSA patients from the no-CPAP group. In addition, all patients completed the MoCA test, a patient health questionnaire (PHQ-9) for depressive symptoms, and a generalized anxiety questionnaire (GAD-7) for anxiety symptoms, at baseline, after 6 months, and after 1 year. Results: At baseline, there were no significant differences between the two groups regarding total MoCA scores, 20.9 ± 3.5 CPAP group to 19.7 ± 2.9 no-CPAP group (p = 0.159), PHQ-9 (p = 0.651), and GAD-7 (p = 0.691). After one year, improvement was observed for a total MoCA score of 22.7 ± 3.5 (p < 0.001) for the CPAP group, and significant variance of score between groups was more accentuated for delayed recall and attention (p < 0.001) sub-topic. Moreover, PHQ-9, GAD-7 scores, and the Epworth Sleepiness Scale (ESS) decreased significantly (p < 0.001) after CPAP therapy. The MoCA score was significantly correlated with years of education (r = 0.74, p < 0.001) and had a negative correlation with body mass index (BMI) (r = −0.34), ESS (r = −0.30) and PHQ-9 (r = −0.34). Conclusions: One year of CPAP adherence improved global cognition associated with OSA.
Evaluation of Pharmacology and Pathophysiology Knowledge of Epilepsy among Senior Pharmacy Students: A Single Center Experience
Authors: Alorfi Nasser M. , Ashour Ahmed M. , Bafhaid Hanouf S. , Alshehri Fahad S.
Published: April 2023

Background and Objectives: Epilepsy is a chronic disease that causes substantial morbidity and mortality. Pharmacists represent an integral role in managing patients with epilepsy. The aim of this study was to evaluate the level of knowledge about the pharmacology and pathophysiology of epilepsy among senior pharmacy students. Materials and Methods: Cross-sectional study using a designed questionnaire to measure the pharmacological and physiological knowledge of senior pharmacy students regarding epilepsy who are studying at Umm Al-Qura University, Makkah, Saudi Arabia, from August to October 2022. Results: A total of 211 senior clinical pharmacy students responded to the questionnaire. The majority of the respondents were 4th year pharmacy students. The numbers of female and male participants were equal (106 and 105 students, respectively). The participants represented an acceptable level of knowledge about the pathophysiology aspects of epilepsy, with a mean total score of 6.22 ± 1.9 out of a maximum score of 10. The respondents reported that epilepsy could be due to genetic predisposition combined with environmental conditions (80.1%) or brain stroke (17.1%). Regarding the respondent knowledge about the pharmacology of epilepsy, the total score was 4.6 ± 2.1 (maximum attainable score: 9). Conclusions: The majority of pharmacy students had knowledge about the pathophysiology concept of the disease; however, low knowledge was shown by the respondents regarding the pharmacology of epilepsy. Thus, there is a need to identify better strategies to improve students’ education.
Biliary and Vascular Complications after Liver Transplantation–From Diagnosis to Treatment
Authors: Gheorghe Gina , Diaconu Camelia , Bungau Simona , Bacalbasa Nicolae , Motas Natalia , Ionescu Vlad-Alexandru
Published: April 2023

The last decades have brought impressive advances in liver transplantation. As a result, there was a notable rise in the number of liver transplants globally. Advances in surgical techniques, immunosuppressive therapies and radiologically guided treatments have led to an improvement in the prognosis of these patients. However, the risk of complications remains significant, and the management of liver transplant patients requires multidisciplinary teams. The most frequent and severe complications are biliary and vascular complications. Compared to vascular complications, biliary complications have higher incidence rates but a better prognosis. The early diagnosis and selection of the optimal treatment are crucial to avoid the loss of the graft and even the death of the patient. The development of minimally invasive techniques prevents surgical reinterventions with their associated risks. Liver retransplantation remains the last therapeutic solution for graft dysfunction, one of the main problems, in this case, being the low number of donors.
Is the Effect of the COVID-19 Vaccine on Heart Rate Variability Permanent?
Authors: Kerkutluoglu Murat , Gunes Hakan , Iyigun Ufuk , Dagli Musa , Doganer Adem
Published: April 2023

Background and Objectives: The risk of autonomic dysfunction with COVID-19 vaccines used worldwide in the COVID-19 pandemic remains a topic of debate. Heart rate variability has a number of parameters that can be used to assess autonomic nervous system dynamics. The aim of this study was to investigate the effect of a COVID-19 vaccine (Pfizer-BioNTech) on heart rate variability and autonomic nervous system parameters, and the duration of the effect. Materials and Methods: A total of 75 healthy individuals who visited an outpatient clinic to receive the COVID-19 vaccination were included in this prospective observational study. Heart rate variability parameters were measured before vaccination and on days 2 and 10 after vaccination. SDNN, rMSSD and pNN50 values were evaluated for time series analyses, and LF, HF, and LF/HV values for frequency-dependent analyses. Results: The SDNN and rMSDD values declined significantly on day 2 after vaccination, while the pNN50 and LF/HF values increased significantly on day 10. The values at pre-vaccination and at day 10 were comparable. The pNN50 and LF/HF values declined significantly on day 2 and increased significantly on day 10. The values at pre-vaccination and at day 10 were comparable. Conclusions: This study showed that the decline in HRV observed with COVID-19 vaccination was temporary, and that the Pfizer-BioNTech COVID-19 vaccination did not cause permanent autonomic dysfunction.
Multimodal Analgesia with Local Wound Infiltration and Intravenous Parecoxib for Thyroidectomy
Authors: Gau Tz-Ping , Wu Sheng-Hua , Huang Jui-Mei , Lu Wen-Ling , Huang Tzu-Yen , Lu I-Cheng , Wu Che-Wei
Published: April 2023

Background and objective: Adequate postoperative pain control is an important component to enhance recovery. Multimodal analgesia with various pain control techniques has been widely used to alleviate postoperative pain. The use of either wound infiltration or a superficial cervical plexus block has been reported to be effective for pain management after thyroid surgery. The present study evaluated the effect of multimodal analgesia using lidocaine wound infiltration combined with intravenous parecoxib for patients monitored after thyroidectomy. Materials and Methods: A total of 101 patients with a multimodal analgesia protocol being monitored after thyroidectomy were enrolled. After the induction of anesthesia, multimodal analgesia was performed through wound infiltration of 1% lidocaine and epinephrine at a ratio of 1:200,000 (5 μg/mL) combined 40 mg intravenous parecoxib before skin excision. Patients were divided into two groups for this retrospective analysis based on the injection dose of lidocaine they received. Patients in Group I (the control, n = 52) received a 5 mL injection solution, while those in Group II (the study, n = 49) received a 10 mL dosage in a time-sequential manner, in accordance with a previous clinical trial. The primary outcome was measuring postoperative pain intensity at rest, as well as during motion and coughing, which was measured at the postoperative anesthetic care unit (PACU) and on the first day after the operation (POD 1) in the ward. Pain intensity was assessed using a numerical rating scale (NRS). The secondary outcomes were postoperative adverse events including anesthetic-related side effects, as well as airway and pulmonary complications. Results: Most of the patients reported no pain or mild pain during the observation period. The patients in Group II had a lower pain intensity during motion than Group I (NRS 1.47 ± 0.89 vs. 1.85 ± 0.96, p = 0.043) when measured at the postoperative anesthetic care unit. Pain intensity during coughing was also significantly lower in the study group than in the control group (NRS 1.61 ± 0.95 vs. 1.96 ± 0.79, p = 0.049) when measured at the postoperative anesthetic care unit. There were no severe adverse events in either of the groups. Only one patient (1.9%) in Group I experienced temporary vocal palsy. Conclusions: The use of lidocaine with an equal volume of intravenous parecoxib provided comparable analgesia with minimal adverse events when monitoring thyroidectomy.
Endocrine Disorders in a Newborn with Heterozygous Galactosemia, Down Syndrome and Complex Cardiac Malformation: Case Report
Authors: Rosca Ioana , Turenschi Alina , Nicolescu Alin , Constantin Andreea Teodora , Canciu Adina Maria , Dica Alice Denisa , Bratila Elvira , Coroleuca Ciprian Andrei , Nastase Leonard
Published: April 2023

Down syndrome is the most common chromosomal abnormality diagnosed in newborn babies. Infants with Down syndrome have characteristic dysmorphic features and can have neuropsychiatric disorders, cardiovascular diseases, gastrointestinal abnormalities, eye problems, hearing loss, endocrine and hematologic disorders, and many other health issues. We present the case of a newborn with Down syndrome. The infant was a female, born at term through c-section. She was diagnosed before birth with a complex congenital malformation. In the first few days of life, the newborn was stable. In her 10th day of life, she started to show respiratory distress, persistent respiratory acidosis, and persistent severe hyponatremia, and required intubation and mechanical ventilation. Due to her rapid deterioration our team decided to do a screening for metabolic disorders. The screening was positive for heterozygous Duarte variant galactosemia. Further testing on possible metabolic and endocrinologic issues that can be associated with Down syndrome was performed, leading to hypoaldosteronism and hypothyroidism diagnoses. The case was challenging for our team because the infant also had multiple metabolic and hormonal deficiencies. Newborns with Down syndrome often require a multidisciplinary team, as besides congenital cardiac malformations they can have metabolic and hormonal deficiencies that can negatively impact their short- and long-term prognosis.
Cannabis Use in Physicians: A Systematic Review and Meta-Analysis
Authors: Naillon Pierre-Louis , Flaudias Valentin , Brousse Georges , Laporte Catherine , Baker Julien S. , Brusseau Valentin , Comptour Aurélie , Zak Marek , Bouillon-Minois Jean-Baptiste , Dutheil Frédéric
Published: April 2023

Background: Cannabis use by physicians can be detrimental for them and their patients. We conducted a systematic review and meta-analysis on the prevalence of cannabis use by medical doctors (MDs)/students. Method: PubMed, Cochrane, Embase, PsycInfo and ScienceDirect were searched for studies reporting cannabis use in MDs/students. For each frequency of use (lifetime/past year/past month/daily), we stratified a random effect meta-analysis depending on specialties, education level, continents, and periods of time, which were further compared using meta-regressions. Results: We included 54 studies with a total of 42,936 MDs/students: 20,267 MDs, 20,063 medical students, and 1976 residents. Overall, 37% had used cannabis at least once over their lifetime, 14% over the past year, 8% over the past month and 1.1 per thousand (‰) had a daily use. Medical students had a greater cannabis use than MDs over their lifetime (38% vs. 35%, p < 0.001), the past year (24% vs. 5%, p < 0.001), and the past month (10% vs. 2%, p < 0.05), without significance for daily use (0.5% vs. 0.05%, NS). Insufficient data precluded comparisons among medical specialties. MDs/students from Asian countries seemed to have the lowest cannabis use: 16% over their lifetime, 10% in the past year, 1% in the past month, and 0.4% daily. Regarding periods of time, cannabis use seems to follow a U-shape, with a high use before 1990, followed by a decrease between 1990 and 2005, and a rebound after 2005. Younger and male MDs/students had the highest cannabis use. Conclusions: If more than a third of MDs tried cannabis at least once in their lifetime, this means its daily use is low but not uncommon (1.1‰). Medical students are the biggest cannabis users. Despite being common worldwide, cannabis use is predominant in the West, with a rebound since 2005 making salient those public health interventions during the early stage of medical studies.
Tentative Approaches for Extraction of Lanthanides from Wastewater with Low Metal Concentration
Authors: Carretas José M. , Ferreira Luís M. , Santos Pedro M. P. , Gomes Susana S. , Araújo Maria Fátima , Maria Leonor , Leal João Paulo
Published: April 2023

Lanthanides are critical elements, and their recovery from wastewater increases the availability of these elements and reduces their impacts on the environment. In this study, tentative approaches to extract lanthanides from low-concentration aqueous solutions were investigated. PVDF membranes soaked with different active compounds or synthesized chitosan-based membranes containing these active compounds were used. The membranes were immersed in 10−4 M of aqueous solutions of selected lanthanides, and their extraction efficiency was assessed using ICP-MS. The PVDF membranes showed quite poor results, with only the membrane with oxamate ionic liquid giving some positive results (0.75 mg of Yb, 3 mg of lanthanides per gram of membrane). However, the chitosan-based membranes led to very interesting results, with the maximum concentration factor for the final solution relative to the initial solution being 13 times higher for Yb, which was obtained with the chitosan–sucrose–citric acid membrane. Several of the chitosan membranes, namely the one with 1-Butyl-3-methylimidazolium-di-(2-ethylhexyl)-oxamate, could extract around 10 mg of lanthanides per gram of membrane, with the better one being the membrane with sucrose/citric acid that achieved more than 18 mg/g of membrane. The use of chitosan for this purpose is a novelty. Since these membranes are easily prepared and have a very low cost, practical applications can be envisaged after further studies to better understand the underlying mechanism.
Insights into Early Steps of Decanoic Acid Self-Assemblies under Prebiotic Temperatures Using Molecular Dynamics Simulations
Authors: Sepulveda Romina V. , Sbarbaro Christopher , Opazo Ma Cecilia , Duarte Yorley , González-Nilo Fernando , Aguayo Daniel
Published: April 2023

The origin of life possibly required processes in confined systems that facilitated simple chemical reactions and other more complex reactions impossible to achieve under the condition of infinite dilution. In this context, the self-assembly of micelles or vesicles derived from prebiotic amphiphilic molecules is a cornerstone in the chemical evolution pathway. A prime example of these building blocks is decanoic acid, a short-chain fatty acid capable of self-assembling under ambient conditions. This study explored a simplified system made of decanoic acids under temperatures ranging from 0 °C to 110 °C to replicate prebiotic conditions. The study revealed the first point of aggregation of decanoic acid into vesicles and examined the insertion of a prebiotic-like peptide in a primitive bilayer. The information gathered from this research provides critical insights into molecule interactions with primitive membranes, allowing us to understand the first nanometric compartments needed to trigger further reactions that were essential for the origin of life.
Nanocarbon-Based Mixed Matrix Pebax-1657 Flat Sheet Membranes for CO2/CH4 Separation
Authors: Vasileiou Athanasios N. , Theodorakopoulos George V. , Karousos Dionysios S. , Bouroushian Mirtat , Sapalidis Andreas A. , Favvas Evangelos P.
Published: April 2023

In the present work, Pebax-1657, a commercial multiblock copolymer (poly(ether-block-amide)), consisting of 40% rigid amide (PA6) groups and 60% flexible ether (PEO) linkages, was selected as the base polymer for preparing dense flat sheet mixed matrix membranes (MMMs) using the solution casting method. Carbon nanofillers, specifically, raw and treated (plasma and oxidized) multi-walled carbon nanotubes (MWCNTs) and graphene nanoplatelets (GNPs) were incorporated into the polymeric matrix in order to improve the gas-separation performance and polymer’s structural properties. The developed membranes were characterized by means of SEM and FTIR, and their mechanical properties were also evaluated. Well-established models were employed in order to compare the experimental data with theoretical calculations concerning the tensile properties of MMMs. Most remarkably, the tensile strength of the mixed matrix membrane with oxidized GNPs was enhanced by 55.3% compared to the pure polymeric membrane, and its tensile modulus increased 3.2 times compared to the neat one. In addition, the effect of nanofiller type, structure and amount to real binary CO2/CH4 (10/90 vol.%) mixture separation performance was evaluated under elevated pressure conditions. A maximum CO2/CH4 separation factor of 21.9 was reached with CO2 permeability of 384 Barrer. Overall, MMMs exhibited enhanced gas permeabilities (up to fivefold values) without sacrificing gas selectivity compared to the corresponding pure polymeric membrane.
Lipoprotein Particles as Shuttles for Hydrophilic Cargo
Authors: Weber Florian , Axmann Markus , Horner Andreas , Schwarzinger Bettina , Weghuber Julian , Plochberger Birgit
Published: April 2023

Lipoprotein particles (LPs) are excellent transporters and have been intensively studied in cardiovascular diseases, especially regarding parameters such as their class distribution and accumulation, site-specific delivery, cellular internalization, and escape from endo/lysosomal compartments. The aim of the present work is the hydrophilic cargo loading of LPs. As an exemplary proof-of-principle showcase, the glucose metabolism-regulating hormone, insulin, was successfully incorporated into high-density lipoprotein (HDL) particles. The incorporation was studied and verified to be successful using Atomic Force Microscopy (AFM) and Fluorescence Microscopy (FM). Single-molecule-sensitive FM together with confocal imaging visualized the membrane interaction of single, insulin-loaded HDL particles and the subsequent cellular translocation of glucose transporter type 4 (Glut4).
Application of Ultrafiltration to Produce Sheep’s and Goat’s Whey-Based Synbiotic Kefir Products
Authors: Pires Arona , Tan Gözdenur , Gomes David , Pereira-Dias Susana , Díaz Olga , Cobos Angel , Pereira Carlos
Published: April 2023

Membrane filtration technologies are the best available tools to manage dairy byproducts such as cheese whey, allowing for the selective concentration of its specific components, namely proteins. Their acceptable costs and ease of operation make them suitable for application by small/medium-scale dairy plants. The aim of this work is the development of new synbiotic kefir products based on sheep and goat liquid whey concentrates (LWC) obtained by ultrafiltration. Four formulations for each LWC based on a commercial kefir starter or traditional kefir, without or with the addition of a probiotic culture, were produced. The physicochemical, microbiological, and sensory properties of the samples were determined. Membrane process parameters indicated that ultrafiltration can be applied for obtaining LWCs in small/medium scale dairy plants with high protein concentration (16.4% for sheep and 7.8% for goats). Sheep kefirs showed a solid-like texture while goat kefirs were liquid. All samples presented counts of lactic acid bacteria higher than log 7 CFU/mL, indicating the good adaptation of microorganisms to the matrixes. Further work must be undertaken in order to improve the acceptability of the products. It could be concluded that small/medium-scale dairy plants can use ultrafiltration equipment to valorize sheep’s and goat’s cheese whey-producing synbiotic kefirs.
Magnesium Oxide Nanoparticles for the Adsorption of Pentavalent Arsenic from Water: Effects of Calcination
Authors: Mehanathan Shaymala , Jaafar Juhana , Nasir Atikah Mohd , Ismail Ahmad Fauzi , Matsuura Takeshi , Othman Mohd Hafiz Dzarfan , Rahman Mukhlis A. , Yusof Norhaniza
Published: April 2023

The occurrence of heavy metal ions in water is intractable, and it has currently become a serious environmental issue to deal with. The effects of calcining magnesium oxide at 650 °C and the impacts on the adsorption of pentavalent arsenic from water are reported in this paper. The pore nature of a material has a direct impact on its ability to function as an adsorbent for its respective pollutant. Calcining magnesium oxide is not only beneficial in enhancing its purity but has also been proven to increase the pore size distribution. Magnesium oxide, as an exceptionally important inorganic material, has been widely studied in view of its unique surface properties, but the correlation between its surface structure and physicochemical performance is still scarce. In this paper, magnesium oxide nanoparticles calcined at 650 °C are assessed to remove the negatively charged arsenate ions from an aqueous solution. The increased pore size distribution was able to give an experimental maximum adsorption capacity of 115.27 mg/g with an adsorbent dosage of 0.5 g/L. Non-linear kinetics and isotherm models were studied to identify the adsorption process of ions onto the calcined nanoparticles. From the adsorption kinetics study, the non-linear pseudo-first order showed an effective adsorption mechanism, and the most suitable adsorption isotherm was the non-linear Freundlich isotherm. The resulting R2 values of other kinetic models, namely Webber-Morris and Elovich, were still below those of the non-linear pseudo-first-order model. The regeneration of magnesium oxide in the adsorption of negatively charged ions was determined by making comparisons between fresh and recycled adsorbent that has been treated with a 1 M NaOH solution.
Analysis of Hollow Section “Y” Connections with the Application of Non-Linear Material Modeling
Authors: Živković Srđan , Stojković Nenad , Turnić Dragana , Spasojević Šurdilović Marija , Branković Jelena Marković
Published: April 2023

The use of welded structural hollow sections in civil engineering is relatively new. Design of connections in steel structures with welded structural hollow sections requires a more specified approach, compared to traditional connections achieved with gusset plates. Stress and local deformations at the connection area are non-linear and very complex. This paper presents the application of non-linear numerical analysis for the determination of the ultimate bearing capacity of “Y” connections. In the analysis, a non-linear material model was applied. In order to validate the applied method of steel modelling, comparative analysis of the analytically and numerically determined ultimate bearing capacity with the experimentally obtained results has been conducted.
Irradiation-Assisted Microstructure Evolution and Mechanical Properties Loss of 310S Welded Joints
Authors: Jiang Yunlu , Kan Ying , Wu Changzhong , Chen Huaining
Published: April 2023

In order to reveal the effect of irradiation damage caused by high-level liquid radioactive wastes on the welded joint of the container, the irradiation-induced microstructure evolution and mechanical properties degradation of the 310S stainless steel welded joints were investigated in this study. For this purpose, the 1.3 MeV 60Co and 2 MeV accelerators were used to simulate irradiation experiments on 310S welded joints. The uniaxial tensile tests characterized the specimens' mechanical properties and fracture morphology. The results revealed that elongation was reduced by about 5% of irradiation damage by 60Co, and the fracture morphology shows a large number of secondary cracks. In contrast, the elongation was recovered irradiated by the accelerator, and the fracture morphology showed a large number of dimples. Following the interrupted creep deformation, creep fracture tests were conducted for irradiation specimens. The 60Co irradiation damage significantly decreases the creep resistance, leading to deformation of creep, which is increased to 1.5 times that of those unirradiated specimens. At the same time, the ductility is seriously degraded for the irradiated creep fracture specimens. As a result, the creep fracture strain of 60Co specimens is reduced to 70% of that of unirradiated specimens. Further, ductility reduction was related to the irradiated hardening by 60Co, while Nano-indenter hardness was 5.9 GPa, higher by 44% than the unirradiated specimens. The results are shown in an enrichment of Cr, C and P elements at phase boundaries for 60Co irradiation specimens, while the magnitude of element segregation increased by the accelerator combination irradiation. Finally, the creep cracking analysis results show intergranular cracking was observed on the surfaces of the irradiated specimens, while the M23C6 has a primary relationship with the intergranular cracks. The synergic effect of irradiation promoted damage, and element segregation was the primary cause of the intergranular cracking of the 310S welded joints.
Correlating Experimental with Theoretical Studies for a New Ionic Liquid for Inhibiting Corrosion of Carbon Steel during Oil Well Acidification
Authors: Toghan Arafat , Fawzy Ahmed , Alakhras Abbas I. , Sanad Moustafa M. S. , Khairy M. , Farag Ahmed A.
Published: April 2023

During the mandatory acidification process in the oil and gas industry, carbon steel unfortunately suffers significant corrosion damage. From this perspective, for the first time a new ionic liquid called 1-(2-(4-bromophenyl)-2-oxoethyl)-4-(tert-butyl)pyridin-1-ium bromide (ILB) has been used as an effective inhibitor for the carbon steel corrosion in aggressive HCl solution (15%) at 298 K. The experiments were managed with a number of different chemical and electrochemical techniques including weight loss, potentiodynamic polarization (PDP), and impedance spectroscopy (EIS). ILB has good inhibitory performance as an acidizing corrosion inhibitor for carbon steel even at low dosing levels of 1 × 10−3 M. The findings were promising as an inhibition efficiency of about 97% was achieved when ILB was added at low concentrations to the corrosive media. EIS results showed a significant rise in charge transfer resistance (Rct) values with increasing doses of ILB. PDP studies confirmed that ILB is a mixed type and obey Langmuir adsorption isotherm with chemical nature. The metal surface morphologies were inspected using a Scanning Electron Microscope (SEM) and an Atomic Force Microscope (AFM). Additionally, Density Functional Theory (DFT) and Molecular Dynamic Simulation (MDS) indicates that ILB molecules function as inhibitors more successfully. There is a high degree of concordance between practical and theoretical studies.
Microstructural Investigation of Some Bronze Artifacts Discovered in a Dacian Site Using Non-Destructive Methods
Authors: Petan Aurora , Petean Ioan , Paltinean Gertrud Alexandra , Filip Miuta Rafila , Borodi Gheorghe , Tudoran Lucian Barbu
Published: April 2023

Dacian civilization flourished on the actual territory of Romania during the Late Iron Age and had its peak from the first century BC to the first century AD. They had intensive relations with Hellenistic and Roman civilizations. Therefore, it is difficult to evaluate the origin of some widely spread artifacts discovered in the Dacian archeological sites. The present research is focused on two bronze artifacts (a bronze coin and a mirror fragment) found in the Alun-Piatra Rosie site and a silver coin found in the Ardeu site. Artifacts were investigated with nondestructive methods such as SEM-EDX for microstructural and elemental characterization, and the crystalline phases were investigated using XRD. Bronze coin proves to be an Istrian issue having an elemental composition of 75.0% Cu, 20.8% Sn, and 4.1% Pb, which corresponds to a structure of Cu grains mixed with Cu5.6Sn grains. The bronze mirror fragment has an elemental composition of 52.3% Cu and 47.7% Sn, which corresponds to a structure containing grains of Cu6Sn5 mixed with grains of Cu41Sn11. It has a smooth surface that was investigated with AFM microscopy, which evidences a Ra roughness of 51 nm for the patina surface and 33.7 nm for the clean metal surface, proving the high quality of the original mirror luster of the artifact. The silver coin was identified as a Radulesti–Hunedoara type meaning that it was produced in local Dacian metallurgic workshops. It has an elemental composition of 63.1% Ag, 25.3% Sn, 7.8% Cu, and small traces of P and Fe, which corresponds to a structure of Ag grains and Ag3Sn grains. Silver coins show that Dacians uses Sn as alloying element in their metallurgic workshops. Istrian bronze coin proves to be typical for Hellenistic or Roman bronze type with Sn content no more than 25% Sn. The bronze mirror fragment has an unusual composition that might be a result of al local metal charge elaboration with several Hellenistic and Roman bronze pieces as raw material and an extra Sn addition during the melting process. This material facilitates the polishing properties of the active surface that has a very low roughness even after 2000 years of ground resting and adherent oxides patina.
Determination of Indolepropionic Acid and Related Indoles in Plasma, Plasma Ultrafiltrate, and Saliva
Authors: Anderson George
Published: April 2023

The microbial metabolite indolepropionic acid (IPA) and related indolic metabolites, including indolecarboxylic acid (ICA), indolelactic acid (ILA), indoleacetic acid (IAA), indolebutyric acid (IBA), indoxylsulfate (ISO4), and indole, were determined in human plasma, plasma ultrafiltrate (UF), and saliva. The compounds were separated on a 150 × 3 mm column of 3 μm Hypersil C18 eluted with a mobile phase of 80% pH 5 0.01 M sodium acetate containing 1.0 g/L of tert-butylammonium chloride/20% acetonitrile and then detected fluorometrically. Levels of IPA in human plasma UF and of ILA in saliva are reported for the first time. The determination of IPA in plasma UF enables the first report of free plasma IPA, the presumed physiologically active pool of this important microbial metabolite of tryptophan. Plasma and salivary ICA and IBA were not detected, consistent with the absence of any prior reported values. Observed levels or limits of detection for other indolic metabolites usefully supplement limited prior reports.
Effect of Cycling Exercise Resisting Electrically Stimulated Antagonist Muscle Contractions in Healthy Males
Authors: Omoto Masayuki , Tsukada Yuya , Hashida Ryuki , Matsuse Hiroo , Tajima Hiroshi , Iwanaga Sohei , Takano Yoshio , Nago Takeshi , Tagawa Yoshihiko , Shiba Naoto
Published: April 2023

A hybrid training system (HTS) combining antagonist muscle electrical stimulation and voluntary muscle contraction has been developed using eccentric antagonist muscle contractions with electrical stimulation as resistance to voluntary muscle contractions. We devised an exercise method using HTS combined with a cycle ergometer (HCE). The purpose of this study was to compare the muscle strength, muscle volume, aerobic functions and lactate metabolism of HCE and a volitional cycle ergometer (VCE). A total of 14 male participants performed exercise on a bicycle ergometer for 30 min per session, 3 times per week for 6 weeks. We divided 14 participants into an HCE group (7 participants) and a VCE group (7 participants). The workload was set at 40% of each participant’s peak oxygen uptake (V.O2peak). Electrodes were placed over each motor point on the quadriceps and hamstrings. The V.O2peak and anaerobic threshold significantly increased before and after training when using HCE rather than VCE. The HCE group had significantly increased extension and flexion muscle strength at 180 degrees/s in post-training measurements over pre-training measurements. Knee flexion muscle strength at 180 degrees/s tended to increase in the HCE group compared to the VCE group. The quadricep muscle cross-sectional area was significantly increased in the HCE group compared to the VCE group. Additionally, the HCE group had significantly decreased maximal lactate, measured every 5 min during exercise at the end of study, between pre and post-training. Thus, HCE may be a more effective training method for muscle strength, muscle mass and aerobic functions at 40% of each participant’s V.O2peak than conventional cycling exercise. HCE could be applied not only as aerobic exercise but also as resistance training.
Identification of Serum Metabolites as Prognostic Biomarkers Following Spinal Cord Injury: A Pilot Study
Authors: Bykowski Elani A. , Petersson Jamie N. , Dukelow Sean , Ho Chester , Debert Chantel T. , Montina Tony , Metz Gerlinde A. S.
Published: April 2023

The assessment, management, and prognostication of spinal cord injury (SCI) mainly rely upon observer-based ordinal scales measures. 1H nuclear magnetic resonance (NMR) spectroscopy provides an effective approach for the discovery of objective biomarkers from biofluids. These biomarkers have the potential to aid in understanding recovery following SCI. This proof-of-principle study determined: (a) If temporal changes in blood metabolites reflect the extent of recovery following SCI; (b) whether changes in blood-derived metabolites serve as prognostic indicators of patient outcomes based on the spinal cord independence measure (SCIM); and (c) whether metabolic pathways involved in recovery processes may provide insights into mechanisms that mediate neural damage and repair. Morning blood samples were collected from male complete and incomplete SCI patients (n = 7) following injury and at 6 months post-injury. Multivariate analyses were used to identify changes in serum metabolic profiles and were correlated to clinical outcomes. Specifically, acetyl phosphate, 1,3,7-trimethyluric acid, 1,9-dimethyluric acid, and acetic acid significantly related to SCIM scores. These preliminary findings suggest that specific metabolites may serve as proxy measures of the SCI phenotype and prognostic markers of recovery. Thus, serum metabolite analysis combined with machine learning holds promise in understanding the physiology of SCI and aiding in prognosticating outcomes following injury.
Sodium-Ion-Free Fermentative Production of GABA with Levilactobacillus brevis CD0817
Authors: Li Haixing , Pei Jinfeng , Wei Cheng , Lin Zhiyu , Pan Hao , Pan Zhenkang , Guo Xinyue , Yu Zhou
Published: April 2023

Gamma-aminobutyric acid (GABA) has positive effects on many physiological processes. Lactic acid bacterial production of GABA is a future trend. This study aimed to produce a sodium-ion-free GABA fermentation process for Levilactobacillus brevis CD0817. In this fermentation, both the seed and fermentation media used L-glutamic acid instead of monosodium L-glutamate as the substrate. We optimized the key factors influencing GABA formation, adopting Erlenmeyer flask fermentation. The optimized values of the key factors of glucose, yeast extract, Tween 80, manganese ion, and fermentation temperature were 10 g/L, 35 g/L, 1.5 g/L, 0.2 mM, and 30 °C, respectively. Based on the optimized data, a sodium-ion-free GABA fermentation process was developed using a 10-L fermenter. During the fermentation, L-glutamic acid powder was continuously dissolved to supply substrate and to provide the acidic environment essential for GABA synthesis. The current bioprocess accumulated GABA at up to 331 ± 8.3 g/L after 48 h. The productivity of GABA was 6.9 g/L/h and the molar conversion rate of the substrate was 98.1%. These findings demonstrate that the proposed method is promising in the fermentative preparation of GABA by lactic acid bacteria.
1H-NMR-Based Metabolic Profiling in Muscle and Liver Tissue of Juvenile Turbot (Scophthalmus maximus) Fed with Plant and Animal Protein Sources
Authors: Hoerterer Christina , Petereit Jessica , Lannig Gisela , Bock Christian , Buck Bela H.
Published: April 2023

Circular economy driven feed ingredients and emerging protein sources, such as insects and microbial meals, has the potential to partially replace fishmeal in diets of high-trophic fish. Even though growth and feed performance are often unaffected at low inclusion levels, the metabolic effects are unknown. This study examined the metabolic response of juvenile turbot (Scophthalmus maximus) to diets with graded fishmeal replacement with plant, animal, and emerging protein sources (PLANT, PAP, and MIX) in comparison to a commercial-like diet (CTRL). A 1H-nuclear magnetic resonance (NMR) spectroscopy was used to assess the metabolic profiles of muscle and liver tissue after feeding the fish the experimental diets for 16 weeks. The comparative approach revealed a decrease in metabolites that are associated with energy deficiency in both tissues of fish fed with fishmeal-reduced diets compared to the commercial-like diet (CTRL). Since growth and feeding performance were unaffected, the observed metabolic response suggests that the balanced feed formulations, especially at lower fishmeal replacement levels, have the potential for industry application.
Design and Simulation of Microbolometer with Dual Cavity for High Figure of Merits
Authors: Aponte Kevin O. Díaz , Xu Yanan , Rana Mukti
Published: April 2023

The rapid expansion of the applications of infrared (IR) sensing in the commercial market has driven the need to develop new materials and detector designs for enhanced performance. In this work, we describe the design of a microbolometer that uses two cavities to suspend two layers (sensing and absorber). Here, we implemented the finite element method (FEM) from COMSOL Multiphysics to design the microbolometer. We varied the layout, thickness, and dimensions (width and length) of different layers one at a time to study the heat transfer effect for obtaining the maximum figure of merit. This work reports the design, simulation, and performance analysis of the figure of merit of a microbolometer that uses GexSiySnzOr thin films as the sensing layer. From our design, we obtained an effective thermal conductance of 1.0135×10−7 W/K, a time constant of 11 ms, responsivity of 5.040×105 V/W, and detectivity of 9.357×107 cm−Hz1/2/W considering a 2 μA bias current.
Micro Electro-Osmotic Thrusters of Power-Law Fluids for Space Propulsion
Authors: Zheng Jiaxuan , Wang Jialu , Jian Yongjun
Published: April 2023

In this article, electro-osmotic thrusters (EOTs), which are full of non-Newtonian power-law fluids with a flow behavior index n of the effective viscosity, are theoretically investigated in a microchannel. Different values of the flow behavior index represent two kinds of non-Newtonian power-law fluids, pseudoplastic fluids (n < 1) and dilatant fluids (n > 1), which have not yet been considered to be used as propellants in micro-thrusters. Analytical solutions of the electric potential and flow velocity are obtained using the Debye–Hückel linearization assumption and the approximate scheme of hyperbolic sine function. Then, thruster performances of power-law fluids, including specific impulse, thrust, thruster efficiency, and thrust-to-power ratio, are explored in detail. Results show that these performance curves strongly depend on the flow behavior index and electrokinetic width. It is noted that the non-Newtonian pseudoplastic fluid is most suitable as a propeller solvent in micro electro-osmotic thrusters owing to its improving or optimizing deficiencies in the performances of the existing Newtonian fluid thrusters.
A CMOS-MEMS Pixel Sensor for Thermal Neutron Imaging
Authors: Mendicino Roberto , Dalla Betta Gian-Franco
Published: April 2023

A monolithic pixel sensor with high spatial granularity (35 × 40 μm2) is presented, aiming at thermal neutron detection and imaging. The device is made using the CMOS SOIPIX technology, with Deep Reactive-Ion Etching post-processing on the backside to obtain high aspect-ratio cavities that will be filled with neutron converters. This is the first monolithic 3D sensor ever reported. Owing to the microstructured backside, a neutron detection efficiency up to 30% can be achieved with a 10B converter, as estimated by the Geant4 simulations. Each pixel includes circuitry that allows a large dynamic range and energy discrimination and charge-sharing information between neighboring pixels, with a power dissipation of 10 µW per pixel at 1.8 V power supply. The initial results from the experimental characterization of a first test-chip prototype (array of 25 × 25 pixels) in the laboratory are also reported, dealing with functional tests using alpha particles with energy compatible with the reaction products of neutrons with the converter materials, which validate the device design.
Unexpected Negative Performance of PdRhNi Electrocatalysts toward Ethanol Oxidation Reaction
Authors: ElSheikh Ahmed , McGregor James
Published: April 2023

Direct ethanol fuel cells (DEFCs) need newly designed novel affordable catalysts for commercialization. Additionally, unlike bimetallic systems, trimetallic catalytic systems are not extensively investigated in terms of their catalytic potential toward redox reactions in fuel cells. Furthermore, the Rh potential to break the ethanol rigid C-C bond at low applied potentials, and therefore enhance the DEFC efficiency and CO2 yield, is controversial amongst researchers. In this work, two PdRhNi/C, Pd/C, Rh/C and Ni/C electrocatalysts are synthesized via a one-step impregnation process at ambient pressure and temperature. The catalysts are then applied for ethanol electrooxidation reaction (EOR). Electrochemical evaluation is performed using cyclic voltammetry (CV) and chronoamperometry (CA). Physiochemical characterization is pursued using X-ray diffraction (XRD), transmission electron microscope (TEM), energy-dispersive X-ray spectroscopy (EDX) and X-ray photoelectron spectroscopy (XPS). Unlike Pd/C, the prepared Rh/C and Ni/C do not show any activity for (EOR). The followed protocol produces alloyed dispersed PdRhNi nanoparticles of 3 nm in size. However, the PdRhNi/C samples underperform the monometallic Pd/C, even though the Ni or Rh individual addition to it enhances its activity, as reported in the literature herein. The exact reasons for the low PdRhNi performance are not fully understood. However, a reasonable reference can be given about the lower Pd surface coverage on both PdRhNi samples according to the XPS and EDX results. Furthermore, adding both Rh and Ni to Pd exercises compressive strain on the Pd lattice, noted by the PdRhNi XRD peak shift to higher angles.