bluuebunny/crossref_metadata_2025 huggingface dataset:
Reconstruction of Composite Stiffness Matrix with Array-Guided Wave-Based Genetic Algorithm
Authors: Liu Menglong , Zhang Yaohui , Li Lun , Chen Gongfa , Cui Fangsen
Published: December 2022

Accurate measurement of the material parameters of composite in a nondestructive manner is of great significance for evaluating mechanical performance. This study proposes to use a genetic algorithm (GA) to reconstruct the stiffness matrix of carbon fiber reinforced polymer (CFRP) with array-guided wave (GW)-based GA. By comparing the numerically calculated GW dispersion curves with the experimental wave number-frequency contour calculated with a two-dimensional Fourier transform (2D-FFT), the matching coefficient is directly obtained as the objective function of the GA, avoiding the overhead of sorting out the respective GW modes. Then the measured stiffness matrix with tensile testing and the longitudinal wave in the unidirectional CFRP is compared with the reconstructed parameters from unidirectional, cross-ply, and quasi-isotropic CFRPs with the GA. For the four independent parameters, excluding C12, an average value of 11.62% for the maximum deviation is achieved among the CFRPs with three stacking sequences, and an average deviation of 11.03% in unidirectional CFRPs is achieved for the parameters measured with different methods. A further correction of fiber orientation results in a relative deviation of only 2.72% for the elastic modulus along the tensile direction, and an expansion of the GW frequency range for the GA narrows down the relative deviation of C12 to 3.9%. The proposed GW-based GA opens up a way of in situ and nondestructive measurement for the composite stiffness matrix.
Formation and Inhibition Mechanism of Na8SnSi6O18 during the Soda Roasting Process for Preparing Na2SnO3
Authors: Su Zijian , Liu Shuo , Han Benlai , Zhang Yuanbo , Jiang Tao
Published: December 2022

To produce Na2SnO3, which is widely used in the ceramics and electroplating industries, a novel process for the preparation of sodium stannate from cassiterite concentrates was developed successfully by the authors’ group. It was found that sodium stannosilicate (Na8SnSi6O18) was easily formed due to the main gangue of quartz in cassiterite concentrates, which was almost insoluble and decreased the quality of Na2SnO3. The formation and transitions of Na8SnSi6O18 in the SnO2–SiO2–Na2CO3 system roasted under a CO–CO2 atmosphere were determined. The results indicated that the formation of Na8SnSi6O18 could be divided into two steps: SnO2 reacted with Na2CO3 to form Na2SnO3, and then Na2SnO3 was rapidly combined with SiO2 and Na2CO3 to form low melting point Na8SnSi6O18. In addition, Na8SnSi6O18 can be decomposed into Na2SiO3 and Na2SnO3 by using excess Na2CO3.
Brief Theoretical Overview of Bi-Fe-O Based Thin Films
Authors: Misiurev Denis , Kaspar Pavel , Holcman Vladimír
Published: December 2022

This paper will provide a brief overview of the unique multiferroic material Bismuth ferrite (BFO). Considering that Bismuth ferrite is a unique material which possesses both ferroelectric and magnetic properties at room temperature, the uniqueness of Bismuth ferrite material will be discussed. Fundamental properties of the material including electrical and ferromagnetic properties also will be mentioned in this paper. Electrical properties include characterization of basic parameters considering the electrical resistivity and leakage current. Ferromagnetic properties involve the description of magnetic hysteresis characterization. Bismuth ferrite can be fabricated in a different form. The common forms will be mentioned and include powder, thin films and nanostructures. The most popular method of producing thin films based on BFO materials will be described and compared. Finally, the perspectives and potential applications of the material will be highlighted.
Chirality-Dependent and Intrinsic Auxeticity for Single-Walled Carbon Nanotubes
Authors: Zhang Hai-Ning , Fan Yin , Shen Hui-Shen
Published: December 2022

Single-walled carbon nanotubes (SWCNTs) have superior mechanical properties which originate from a strong C-C covalent bond and unique nanostructure. Chirality, one of the helical structural parameters of SWCNTs, leads to differences in mechanical performance. In this work, molecular dynamics (MD) simulation was performed to analyze engineering Poisson’s ratio (EPR) and incremental Poisson’s ratio (IPR) of SWCNTs with different chiral angles, respectively, under tensile and compressive load, as well as the chiral effect on rigidity. We reported the minimum EPR for (4, 1) SWCNT and obtained the distribution and trend of EPR which is dependent on chiral index m. In addition, a new observation showed two exactly opposite trends of EPR existing not only in tension and compression but also in the longitudinal and radial directions. Furthermore, we found that the critical strain, over which SWCNT would be auxetic, ranged from 6% to 18% and was also chirality-dependent. Three representative SWCNTs with chiral angle of 0° (zigzag), 10.89° (chiral), and 30° (armchair) were selected for the mechanism study of auxeticity. Finally, a method of the contribution to radial strain for two main deformation modes proposed in this paper could well explain the negative IPR phenomenon.
Structure Evolution and Properties Modification for Reaction-Bonded Silicon Carbide
Authors: Li Wei , Zhang Ge , Cui Congcong , Bao Jianxun , Guo Conghui , Xu Chuanxiang , Zhang Wei , Zhu Wanli
Published: December 2022

Complex structure reaction-bonded silicon carbide (RB-SiC) can be prepared by reactive melt infiltration (RMI) and digital light processing (DLP). However, the strength and modulus of RB-SiC prepared by DLP are not sufficient, due to its low solid content (around 40 vol.%), compared with the traditional fabrication techniques (solid content > 60 vol.%). With this understanding, a new method to improve the properties of RB-SiC was proposed, by the impregnation of composite precursor into the porous preform. The composite precursor was composed of phenolic (PF) resin and furfuryl alcohol (FA). PF and FA were pyrolyzed at 1850 °C to obtain amorphous carbon and graphite into the porous preform, respectively. The effects of multiphase carbon on the microstructure and performance of RB-SiC was studied. When the mass ratio of PF to FA was 1/4, the solid content of RB-SiC increased from 40 vol.% to 68.6 vol.%. The strength, bulk density and modulus were 323.12 MPa, 2.94 g/cm3 and 348.83 Gpa, respectively. This method demonstrated that the reaction process between liquid Si and carbon could be controlled by the introduction of multiphase carbon into the porous preforms, which has the potential to regulate the microstructure and properties of RB-SiC prepared by additive manufacturing or other forming methods.
Excitonic Mechanisms of Stimulated Emission in Low-Threshold ZnO Microrod Lasers with Whispering Gallery Modes
Authors: Tarasov Andrey P. , Muslimov Arsen E. , Kanevsky Vladimir M.
Published: December 2022

Whispering gallery mode (WGM) ZnO microlasers gain attention due to their high Q-factors and ability to provide low-threshold near-UV lasing. However, a detailed understanding of the optical gain mechanisms in such structures has not yet been achieved. In this work, we study the mechanisms of stimulated emission (SE) in hexagonal ZnO microrods, demonstrating high-performance WGM lasing with thresholds down to 10–20 kW/cm2 and Q-factors up to ~3500. The observed SE with a maximum in the range of 3.11–3.17 eV at room temperature exhibits a characteristic redshift upon increasing photoexcitation intensity, which is often attributed to direct recombination in the inverted electron-hole plasma (EHP). We show that the main contribution to room-temperature SE in the microrods studied, at least for near-threshold excitation intensities, is made by inelastic exciton-electron scattering rather than EHP. The shape and perfection of crystals play an important role in the excitation of this emission. At lower temperatures, two competing gain mechanisms take place: exciton-electron scattering and two-phonon assisted exciton recombination. The latter forms emission with a maximum in the region near ~3.17 eV at room temperature without a significant spectral shift, which was observed only from weakly faceted ZnO microcrystals in this study.
Effect and Mechanism of Solidified Microstructure on Deformation Behavior, Mechanical Properties, and Residual Stress of Cu-Ni-Si Alloy
Authors: Liao Wanneng , Zhang Chenxing , Qiang Hui , Song Weifei , Ren Hongwen
Published: December 2022

Cu-Ni-Si alloy is the key raw material for the lead frame of large integrated circuits. The disordered grain orientation of alloy billet, high hardening rate, residual stress, and poor surface quality of cold working strips seriously affect its processability. In order to improve the cold-working properties of Cu-Ni-Si alloy, two kinds of C70250 copper alloy strips were produced through hot mold continuous casting (HMCC) and cold mold continuous casting (CMCC) technology. The effects of solidified microstructure on the cold-working deformation behavior, mechanical properties, and residual stress of the alloy were studied. The results show that C70250 copper alloys with columnar grain and equiaxed grain were prepared through HMCC and CMCC. After a 98% reduction in cold rolling, columnar grain strip surface quality was very good, and the elongation was still as high as 3.2%, which is 2.9 times that of equiaxed grain alloy. The residual stress of equiaxed grain strips reached 363 MPa, which is 2.7 times that of columnar grain strips. During the cold rolling process, equiaxed grain strips are prone to cause intersecting plane dislocations, stacking faults, shear bands, and grain breakage during large deformation cold rolling. The columnar grain strip causes parallel plane dislocations, stacking faults, and shearbands. Furthermore, the deformation structure was found to be uniform, and, ultimately, the alloy formed a fibrous structure. Therefore, the elongation and latter distortion of columnar grain strips improved after being put through large deformation cold rolling, which greatly reduced residual stress.
Effects of UV Absorber on Zirconia Fabricated with Digital Light Processing Additive Manufacturing
Authors: Kang Jin-Ho , Sakthiabirami Kumaresan , Kim Hyun-Ah , Hosseini Toopghara Seyed Aliakbar , Jun Mee-Jin , Lim Hyun-Pil , Park Chan , Yun Kwi-Dug , Park Sang-Won
Published: December 2022

This study evaluated the effect of UV absorbers on the dimensional accuracy of zirconia specimens fabricated by additive manufacturing using a digital light process. Zirconia suspension for additive manufacturing was prepared by setting the volume fractions (0, 0.005, 0.05, and 0.1%) of various UV absorbers. The effect of UV absorber content was evaluated through curing thickness, geometric overgrowth model design, linear deviation, and microstructure evaluation before and after sintering. Statistical analysis was performed by Kruskal–Wallis H and post-tested by the Bonferroni correction method. There was no significant difference in the cure depth according to the presence or absence of the UV absorber, the difference in geometric overgrowth was from 2.1 to 12.5%, and the overgrowth significantly decreased as the amount of added UV absorber increased. This result may contribute to improved precision of 3D multilayer ceramic products.
Silicone Materials for Flexible Optoelectronic Devices
Authors: Miroshnichenko Anna S. , Neplokh Vladimir , Mukhin Ivan S. , Islamova Regina M.
Published: December 2022

Polysiloxanes and materials based on them (silicone materials) are of great interest in optoelectronics due to their high flexibility, good film-forming ability, and optical transparency. According to the literature, polysiloxanes are suggested to be very promising in the field of optoelectronics and could be employed in the composition of liquid crystal devices, computer memory drives organic light emitting diodes (OLED), and organic photovoltaic devices, including dye synthesized solar cells (DSSC). Polysiloxanes are also a promising material for novel optoectronic devices, such as LEDs based on arrays of III–V nanowires (NWs). In this review, we analyze the currently existing types of silicone materials and their main properties, which are used in optoelectronic device development.
Acoustic Feature Extraction Method of Rotating Machinery Based on the WPE-LCMV
Authors: Wu Peng , Yu Gongye , Dong Naiji , Ma Bo
Published: December 2022

Fault diagnosis plays an important role in the safe and stable operation of rotating machinery, which is conducive to industrial development and economic improvement. However, effective feature extraction of rotating machinery fault diagnosis is difficult in the complex sound field with characteristics of reverberation and multi-dimensional signals. Therefore, this paper proposes a novel acoustic feature extraction method of the rotating machinery based on the Weighted Prediction Error (WPE) integrating the Linear Constrained Minimum Variance (LCMV). The de-reverberation signal is obtained by inputting multi-channel signals into the WPE algorithm using an adaptive optimal parameters selection function with the sound field changes. Then, the incident angle going from the fault source to the center of the microphone array is calculated from the full-band sound field distribution, and the signal is de-noised and fused using the LCMV. Finally, the fault feature frequency is extracted from the fused signal envelope spectrum. The results of fault data analysis of the centrifugal pump test bench show that the Envelope Harmonic Noise Ratio (EHNR) is more than twice that of the original signal after the WPE-LCMV processing. Compared to the Recursive Least Squares and the Resonance Sparse Signal Decomposition (RLS-RSSD) and the parameter optimized Variational Mode Decomposition (VMD), the EHNR has a higher value for all types of faults after applying the WPE-LCMV processing. Furthermore, the proposed method can effectively extract the frequency of bearing faults.
DC-Link Electrolytic Capacitors Monitoring Techniques Based on Advanced Learning Intelligence Techniques for Three-Phase Inverters
Authors: Dang Hoanglong , Park Hyejin , Kwak Sangshin , Choi Seungdeog
Published: December 2022

The reliability of the electronic converter is a vital concern in an industrialized area. Capacitors are critical in electronic converters and are more likely to fail than other electronic gears. Due to aging, the capacitor progressively loses its original quality and capacitance, and the equivalent series resistance escalates. Hence, condition monitoring is a fundamental procedure for evaluating capacitor health that affords prognostic repairs to guarantee stability in power networks. The ESR and capacitance of the capacitor are commonly employed to estimate the condition grade. This study proposes an estimation scheme that utilizes the source current to assess the health condition of an aluminum capacitor. Several advanced intelligence techniques are adopted to estimate the parameters of an AEC in a three-phase inverter system. First, different signals used as inputs, such as input power, capacitor current, voltage, and power, output current, voltage, and power, are analyzed using fast Fourier transform and discrete wavelet transform analysis. Then, various indexes of the analyzed signals, such as RMS, average, median, and variance, are used as the inputs in learning models to monitor the AEC’s parameters. In addition, various input signals are combined to obtain the best combinations for capacitor monitoring. The estimated results prove that utilizing the source current combined with selected indexes improves the monitoring accuracy of the AEC’s health status.
An Interval Approach for Robust Parameterization of Controllers for Electric Drives
Authors: Schäfer Philipp , Krebs Stefan
Published: December 2022

Uncertain models, e.g., due to component variations and measurement errors during system identification, in combination with the desire to be able to provide guarantees regarding system performances a priori, represent major challenges for users when designing controllers on the basis of models. The aim of this publication is to mitigate this obstacle in the design. For this purpose, criteria of classical control engineering are combined with interval arithmetic in general and the SIVIA algorithm in particular. Thereby, the approach is valid for linear dead time systems. The algorithm evaluates performance criteria for closed interval-bounded sets of parameter values in a single iteration. When overestimation prevents a definite result, the size of the parameter set is recursively reduced by bisecting the evaluated set. The application of the methodology to the controller design for an electromechanical linear actuator shows that the approach not only contributes to theory but can also simplify the practical controller design, especially in the area of electric drives.
Modeling and Optimization of a Micro-Channel Gas Cooler for a Transcritical CO2 Mobile Air-Conditioning System
Authors: Ullah Naveed , Ishaque Shehryar , Kim Man-Hoe , Choi Sanghun
Published: December 2022

This study focuses on developing and optimizing of a microchannel gas cooler model for evaluating the performance of a transcritical CO2 mobile air-conditioning system. A simulation model is developed with the aid of MATLAB R2022a. A segment-by-segment modeling approach is utilized by applying the effectiveness-NTU method. State-of-the-art heat transfer and pressure drop correlations are used to obtain air and refrigerant side heat transfer coefficients and friction factors. The developed model is validated through a wide range of available experimental data and is able to predict a gas cooler capacity and pressure drop within an acceptable range of accuracy. The average errors for a gas cooler capacity and pressure drop are 3.79% and 10.24%, respectively. Furthermore, a parametric optimization method is applied to obtain optimal microchannel heat exchanger dimensions, including the number of tubes, microchannel ports, and passes. Different combinations were selected within the practical range to obtain optimal dimensions while keeping the total core volume constant. The simultaneous effect of the number of tubes, the number of ports in each tube, and the number of passes is determined. The objective of the current optimization technique is to minimize the pressure drop for the specific design capacity under different operating conditions without changing the overall volume of the gas cooler. The average pressure drop reduction for the optimal geometry as compared with the baseline geometry under all operating conditions is about 15%. The results from this study can be used to select an optimal geometric design for the required design capacity with a minimal pressure drop without the need for expensive prototype development and testing.
Photovoltaic Models’ Parameter Extraction Using New Artificial Parameterless Optimization Algorithm
Authors: Alanazi Mohana , Alanazi Abdulaziz , Almadhor Ahmad , Rauf Hafiz Tayyab
Published: December 2022

Identifying parameters in photovoltaic (PV) cell and module models is one of the primary challenges of the simulation and design of photovoltaic systems. Metaheuristic algorithms can find near-optimal solutions within a reasonable time for such challenging real-world optimization problems. Control parameters must be adjusted with many existing algorithms, making them difficult to use. In real-world problems, many of these algorithms must be combined or hybridized, which results in more complex and time-consuming algorithms. This paper presents a new artificial parameter-less optimization algorithm (APLO) for parameter estimation of PV models. New mutation operators are designed in the proposed algorithm. APLO’s exploitation phase is enhanced by each individual searching for the best solution in this updating operator. Moreover, the current best, the old best, and the individual’s current position are utilized in the differential term of the mutation operator to assist the exploration phase and control the convergence speed. The algorithm uses a random step length based on a normal distribution to ensure population diversity. We present the results of a comparative study using APLO and well-known existing parameter-less meta-heuristic algorithms such as grey wolf optimization, the salp swarm algorithm, JAYA, teaching-learning based optimization, colliding body optimization, as well as three major parameter-based algorithms such as differential evolution, genetic algorithm, and particle swarm optimization to estimate the parameters of PV the modules. The results revealed that the proposed algorithm could provide excellent exploration–exploitation balance and consistency during the iterations. Furthermore, the APLO algorithm shows high reliability and accuracy in identifying the parameters of PV cell models.
On Grill Sβ-Open Set in Grill Topological Spaces
Authors: Kalaivani Nagarajan , Rahman Khaleel Fayaz Ur , Čepová Lenka , Čep Robert
Published: December 2022

In this article we originate a new class of Grill Set, namely GSβ-Open Set, which is parallel to the β Open Set in Grill Topological Space (X, θ, G). In addition, we entitle GSβ-continuous and GSβ-open functions by applying a GSβ-Open Set and we review some of its important properties. Many examples are given to explain the concept lucidly. The properties of GSβ open sets are investigated and studied. The theorems based on the arbitrary union and finite intersections are discussed with counter examples. Moreover, some operators like GSβ−closure and GSβ−interior are introduced and investigated. The concept of GSβ−continuous functions are compared with the idea of G−Semi Continuous function. The theorems based on GSβ−continunity have been proved.
Detection and Prediction of Chipping in Wafer Grinding Based on Dicing Signal
Authors: Chang Bao Rong , Tsai Hsiu-Fen , Mo Hsiang-Yu
Published: December 2022

Simple regression cannot wholly analyze large-scale wafer backside wall chipping because the wafer grinding process encounters many problems, such as collected data missing, data showing a non-linear distribution, and correlated hidden parameters lost. The objective of this study is to propose a novel approach to solving this problem. First, this study uses time series, random forest, importance analysis, and correlation analysis to analyze the signals of wafer grinding to screen out key grinding parameters. Then, we use PCA and Barnes-Hut t-SNE to reduce the dimensionality of the key grinding parameters and compare their corresponding heat maps to find out which dimensionality reduction method is more sensitive to the chipping phenomenon. Finally, this study imported the more sensitive dimensionality reduction data into the Data Driven-Bidirectional LSTM (DD-BLSTM) model for training and predicting the wafer chipping. It can adjust the key grinding parameters in time to reduce the occurrence of large-scale wafer chipping and can effectively improve the degree of deterioration of the grinding blade. As a result, the blades can initially grind three pieces of the wafers without replacement and successfully expand to more than eight pieces of the wafer. The accuracy of wafer chipping prediction using DD-BLSTM with Barnes-Hut t-SNE dimensionality reduction can achieve 93.14%.
Mode of Delivery and Neonatal Outcome in Adolescent Pregnancy (13–16 Years Old) Associated with Anemia
Authors: Uzunov Ana Veronica , Cîrstoiu Monica Mihaela , Secară Diana Cristina , Crîngu-Ionescu Antoniu , Matei Alexandra , Mehedințu Claudia , Varlas Valentin Nicolae
Published: December 2022

Background: Adolescent pregnancy represents an important public-health problem due to its maternal and fetal outcomes. Adolescent patients are predisposed to multiple obstetrical complications, including anemia and preterm birth which has a higher incidence among this population; withal, in the specialty literature, anemia is considered to be a risk factor for preterm delivery; furthermore, multiple studies have demonstrated that a very young age is an independent risk factor for preterm birth. Objectives: The study aims to reveal if anemia during adolescent pregnancy has a negative impact on the time and mode of delivery and newborns’ outcomes. Patients and methods: We performed a retrospective multicentric study on adolescent pregnancy. We analyzed 172 patients aged between 13 and 16 years who delivered in two large tertiary hospitals between 1 October 2018 and 15 April 2022. We divided the patients into two groups—a study group (n = 64) with anemia and a control group (n = 108) without anemia. We evaluated the modes of delivery, the times of birth, and the neonatal outcomes by 1-min newborn’s Apgar score, neonatal intensive-care unit (NICU) admission, and the newborns’ weights. Results: The rate of cesarean section was higher in patients with anemia than in the control group (45.31% vs. 38.88%, p < 0.001). We found that patients between 13 and 16 years diagnosed with anemia have a higher risk of preterm birth than those without anemia (35.93% vs. 21.29%, p < 0.001); however, an increased rate of LBW neonates was observed in the anemic adolescent group ≤14 years (p < 0.001). Regarding the newborns’ 1-min Apgar score, NICU admission, no statistically significant differences were recorded between the two groups according to the severity of anemia. In the anemic patients’ group, prenatal screening was identified in 9.37% of cases, while in the control group, in 16.67% (p = 0.034), which represents negative predictive factors, along with a low socio-economic status for the presence of anemia in young adolescent patients. Conclusions: Anemia is a risk factor for preterm birth, LBW, and cesarean section in young adolescent pregnancy. The association of lack of prenatal care and low socio-economic status worsens maternal and neonatal outcomes.
Surveillance of Side Effects after Two Doses of COVID-19 Vaccines among Patients with Comorbid Conditions: A Sub-Cohort Analysis from Saudi Arabia
Authors: Mallhi Tauqeer Hussain , Khan Yusra Habib , Butt Muhammad Hammad , Salman Muhammad , Tanveer Nida , Alotaibi Nasser Hadal , Alzarea Abdulaziz Ibrahim , Alanazi Abdullah Salah
Published: December 2022

Background: Individuals with underlying chronic illnesses have demonstrated considerable hesitancy towards COVID-19 vaccines. These concerns are primarily attributed to their concerns over the safety profile. Real-world data on the safety profile among COVID-19 vaccinees with comorbid conditions are scarce. This study aimed to ascertain the side-effects profile after two doses of COVID-19 vaccines among chronic-disease patients. Methodology: A cross-sectional questionnaire-based study was conducted among faculty members with comorbid conditions at a public educational institute in Saudi Arabia. A 20-item questionnaire recorded the demographics and side effects after the two doses of COVID-19 vaccines. The frequency of side effects was recorded following each dose of vaccine, and the association of the side-effects score with the demographics was ascertained through appropriate statistics. Results: A total of 204 patients with at least one comorbid condition were included in this study. A total of 24 side effects were reported after the first dose and 22 after second dose of the COVID-19 vaccine. The incidence of at least one side effect was 88.7% and 95.1% after the first and second doses of the vaccine, respectively. The frequent side effects after the first dose were pain at the injection site (63.2%), fatigue (58.8%), fever (47.5%), muscle and joint pain (38.7%), and headache (36.3%). However, pain at the injection site (71.1%), muscle and joint pain (62.7%), headache (49.5%), fever (45.6%), and stress (33.3%) were frequent after the second dose. The average side-effects score was 4.41 ± 4.18 (median: 3, IQR: 1, 6) and 4.79 ± 3.54 (median 4, IQR: 2, 6) after the first and second dose, respectively. Female gender, diabetes mellitus, hypertension, hyperlipidemia, comorbidity > 2, family history of COVID-19, and the AstraZeneca vaccine were significantly associated with higher side-effect scores. Only 35.8% of study participants were satisfied with the safety of COVID-19 vaccines. Conclusions: Our analysis showed a high proportion of transient and short-lived side effects of Pfizer and AstraZeneca vaccines among individuals with chronic illnesses. However, the side-effects profile was comparable with the safety reports of phase 3 clinical trials of these vaccines. The frequency of side effects was found to be associated with certain demographics, necessitating the need for further investigations to establish a causal relationship. The current study’s findings will help instill confidence in the COVID-19 vaccines among people living with chronic conditions, overcome vaccine hesitancy, and increase vaccine coverage in this population.
Safety and Efficacy of Simultaneous Resection of Gastric Carcinoma and Synchronous Liver Metastasis—A Western Center Experience
Authors: Minciuna Corina-Elena , Tudor Stefan , Micu Alexandru , Diaconescu Andrei , Alexandrescu Sorin Tiberiu , Vasilescu Catalin
Published: December 2022

Background and objectives: Gastric cancer (GC) is often diagnosed in the metastatic stage. Palliative systemic therapy is still considered the gold standard, even for patients with resectable oligometastatic disease. The aim of the current study is to assess the potential benefit of up-front gastric and liver resection in patients with synchronous resectable liver-only metastases from GC (LMGC) in a Western population. Materials and Methods: All patients with GC and synchronous LMGC who underwent gastric resection with or without simultaneous resection of LMs between January 1997 and December 2016 were selected from the institutional records. Those with T4b primary tumors or with unresectable or more than three LMs were excluded from the analysis. All patients who underwent emergency surgery for hemorrhagic shock or gastric perforation were also excluded. Results: Out of 28 patients fulfilling the inclusion criteria, 16 underwent simultaneous gastric and liver resection (SR group), while 12 underwent palliative gastric resection (GR group). The median overall survival (OS) of the entire cohort was of 18.81 months, with 1-, 3- and 5-year OS rates of 71.4%, 17.9% and 14.3%, respectively. The 1-, 3- and 5-year OS rates in SR group (75%, 31.3% and 25%, respectively) were significantly higher than those achieved in GR group (66.7%, 0% and 0%, respectively; p = 0.004). Multivariate analysis of the entire cohort revealed that the only independent prognostic factor associated with better OS was liver resection (HR = 3.954, 95% CI: 1.542–10.139; p = 0.004). Conclusions: In a Western cohort, simultaneous resection of GC and LMGC significantly improved OS compared to patients who underwent palliative gastric resection.
Effects of Pressure on Homogeneous Nucleation and Growth during Isothermal Solidification in Pure Al: A Molecular Dynamics Simulation Study
Authors: Chen Xiaohua , Fan Weijie , Jiang Wenwen , Lin Deye , Wang Zidong , Jiang Simeng
Published: December 2022

Effects of different pressures on the isothermal-solidification process of pure Al were studied by molecular dynamics (MD) simulation using the embedded-atom method (EAM). Al was first subjected to a rapid-cooling process, and then it was annealed under different pressures conditions. Mean first-passage times (MFPT) method, Johnson-Mehl-Avrami (JMA) law, and X-ray diffraction (XRD) simulation analysis method were used to qualify the solidification- kinetic processing. Nucleation rate, critical-nucleus size, Avrami exponent, growth exponent, and crystallite size were calculated. Results show that the nucleation rate increases as the pressure increases. The change of critical-nucleation size is not obvious as the pressure increases. With the pressure increasing, growth exponent decreases, indicative of decreased grain-growth rate. It was also found that with the pressure increasing, the Avrami exponent decreases, indicating that the increased pressure has an effect on growth modes during solidification, which changes from three-dimensional growth to one-dimensional growth. Results of XRD simulation shows that with pressure increasing, crystallite size decreases.
Bioactive Compounds from Endophytic Bacteria Bacillus subtilis Strain EP1 with Their Antibacterial Activities
Authors: Numan Muhammad , Shah Muddaser , Asaf Sajjad , Ur Rehman Najeeb , Al-Harrasi Ahmed
Published: December 2022

Endophytic bacteria boost host plant defense and growth by producing vital compounds. In the current study, a bacterial strain was isolated from the Boswellia sacra plant and identified as Bacillus subtilis strain EP1 (accession number: MT256301) through 16S RNA gene sequencing. From the identified bacteria, four compounds—1 (4-(4-cinnamoyloxy)phenyl)butanoic acid), 2 (cyclo-(L-Pro-D-Tyr)), 3 (cyclo-(L-Val-L-Phe)), and 4 (cyclo-(L-Pro-L-Val))—were isolated and characterized by 1D and 2D NMR and mass spectroscopy. Moreover, antibacterial activity and beta-lactam-producing gene inhibition (δ-(l-α-aminoadipyl)-l-cysteinyl-d-valine synthetase (ACVS) and aminoadipate aminotransferase (AADAT)) assays were performed. Significant antibacterial activity was observed against the human pathogenic bacterial strains (E. coli) by compound 4 with a 13 ± 0.7 mm zone of inhibition (ZOI), followed by compound 1 having an 11 ± 0.7 mm ZOI. In contrast, the least antibacterial activity among the tested samples was offered by compound 2 with a 10 ± 0.9 mm ZOI compared to the standard (26 ± 1.2 mm). Similarly, the molecular analysis of beta-lactam inhibition determined that compounds 3 and 4 inhibited the two genes (2- to 4-fold) in the beta-lactam biosynthesis (ACVS and AADAT) pathway. From these results, it can be concluded that future research on these compounds could lead to the inhibition of antibiotic-resistant pathogenic bacterial strains.
Internet of Things-Based ECG and Vitals Healthcare Monitoring System
Authors: Heaney James , Buick Jamie , Hadi Muhammad Usman , Soin Navneet
Published: December 2022

Health monitoring and its associated technologies have gained enormous importance over the past few years. The electrocardiogram (ECG) has long been a popular tool for assessing and diagnosing cardiovascular diseases (CVDs). Since the literature on ECG monitoring devices is growing at an exponential rate, it is becoming difficult for researchers and healthcare professionals to select, compare, and assess the systems that meet their demands while also meeting the monitoring standards. This emphasizes the necessity for a reliable reference to guide the design, categorization, and analysis of ECG monitoring systems, which will benefit both academics and practitioners. We present a complete ECG monitoring system in this work, describing the design stages and implementation of an end-to-end solution for capturing and displaying the patient’s heart signals, heart rate, blood oxygen levels, and body temperature. The data will be presented on an OLED display, a developed Android application as well as in MATLAB via serial communication. The Internet of Things (IoT) approaches have a clear advantage in tackling the problem of heart disease patient care as they can transform the service mode into a widespread one and alert the healthcare services based on the patient’s physical condition. Keeping this in mind, there is also the addition of a web server for monitoring the patient’s status via WiFi. The prototype, which is compliant with the electrical safety regulations and medical equipment design, was further benchmarked against a commercially available off-the-shelf device, and showed an excellent accuracy of 99.56%.
Design of Longitudinal–Torsional Transducer and Directivity Analysis during Ultrasonic Vibration-Assisted Milling of Honeycomb Aramid Material
Authors: Zhang Mingxing , Ma Zuotian , Wang Xiaodong , Meng Ting , Li Xiangqun
Published: December 2022

This paper presents a longitudinal–torsional transducer for use during the ultrasonic vibration-assisted milling (UVAM) of honeycomb aramid material. The mechanism of longitudinal–torsional conversion was analyzed to guide the design of a vibration transducer. The transducer features five spiral grooves around the front cover plate, which function under the excitation of a group of longitudinal piezoelectric ceramics. A portion of the longitudinal vibration was successfully converted into torsional vibration. The resonant frequency, longitudinal vibration displacement and torsional amplitude at the top of the disk milling cutter were 24,609 Hz, 19 μm and 9 μm, respectively. In addition, the directivity of the longitudinal–torsional transducer was theoretically analyzed. Compared with conventional milling, UVAM with the longitudinal-torsional could significantly reduce the cutting force (40–50%) and improve the machining stability.
Research on Effects of Dust Removal Using Ultrasonic Vibrators
Authors: Li Chong , Chen Ruimin , Gao Da
Published: December 2022

This work presents two types of ultrasonic vibrators in order to comparatively analyze their dust removal properties for microscopic particles. The vibrators were constructed by pasting four piezoceramic (PZT) plates onto the upper surface of a rectangular metal substrate. The longitudinal or bending mode is excited to form a standing wave in the vibrators. The superposition of the longitudinal and bending modes generates a traveling wave. Because the bending and longitudinal vibrations are two different modes, the process of tuning their resonant frequencies to be close is necessary for the traveling wave vibrator. The structural parameters of the vibrators were optimized by the finite element method. During experiments, the dust removal performances of these vibrators were evaluated by dumping cigarette ash or alumina powders randomly on the surface of the prototype vibrators. The measured experimental results indicate that the dust removal performance of the traveling wave oscillator is better than that of the standing wave oscillator. The two operating modes of the traveling wave vibrator produce orthogonal vibration displacements on the vibrator driving points. Vibration in one direction generates friction force, which drives adherent dust particles. Vibration in the other direction provides intermittent contact pressure between the vibrators and deposited dust particles. The synthesized elliptical motion of vibrator particles helps to improve the dust removal characteristics of the vibrators. The simple structure of the developed vibrators makes them the most promising candidates for dust removal from engines, camera lenses, car windows, and navigation systems.
High-Precision Wafer Bonding Alignment Mark Using Moiré Fringes and Digital Grating
Authors: Fan Jianhan , Lu Sen , Zou Jianxiao , Yang Kaiming , Zhu Yu , Liao Kaiji
Published: December 2022

This paper investigates a moiré-based mark for high-precision wafer bonding alignment. During alignment, the mark is combined with digital grating, which has the benefits of high precision and small size. A digital grating is superimposed on the mark to generate moiré fringes. By performing a phase calculation on the moiré fringe images corresponding to the upper and lower wafers, the relative offset of the upper and lower wafers can be accurately calculated. These moiré fringes are exceptionally stable, thereby enhancing the alignment stability. In this study, through practical experiments, we tested the rationality and practicability of the mark.
“Freezing” Thermophiles: From One Temperature Extreme to Another
Authors: Milojevic Tetyana , Cramm Margaret Anne , Hubert Casey R. J. , Westall Frances
Published: December 2022

New detections of thermophiles in psychrobiotic (i.e., bearing cold-tolerant life forms) marine and terrestrial habitats including Arctic marine sediments, Antarctic accretion ice, permafrost, and elsewhere are continually being reported. These microorganisms present great opportunities for microbial ecologists to examine biogeographical processes for spore-formers and non-spore-formers alike, including dispersal histories connecting warm and cold biospheres. In this review, we examine different examples of thermophiles in cryobiotic locations, and highlight exploration of thermophiles at cold temperatures under laboratory conditions. The survival of thermophiles in psychrobiotic environments provokes novel considerations of physiological and molecular mechanisms underlying natural cryopreservation of microorganisms. Cultures of thermophiles maintained at low temperature may serve as a non-sporulating laboratory model for further exploration of metabolic potential of thermophiles at psychrobiotic temperatures, as well as for elucidating molecular mechanisms behind natural preservation and adaptation to psychrobiotic environments. These investigations are highly relevant for the search for life on other cold and icy planets in the Solar System, such as Mars, Europa and Enceladus.
Biochars and Activated Biocarbons Prepared via Conventional Pyrolysis and Chemical or Physical Activation of Mugwort Herb as Potential Adsorbents and Renewable Fuels
Authors: Wiśniewska Małgorzata , Rejer Kacper , Pietrzak Robert , Nowicki Piotr
Published: December 2022

The main objective of this study was to prepare a series of biochars and activated biocarbons via conventional pyrolysis as well as chemical or physical activation of solid residue after solvent extraction of wild growing plant (popular weed)–mugwort. The influence of the variant of the thermochemical treatment of the precursor on such parameters as elemental composition, textural parameters, acidic-basic character of the surface as well as adsorption abilities of the prepared carbonaceous materials was checked. Moreover, the suitability of the biochars prepared as renewable fuels was also investigated. It has been shown that the products obtained from the mugwort stems differ in many respects from the analogous materials obtained from mugwort leaves. The products were micro/mesoporous materials with surface area reaching 974.4 m2/g and total pore volume–1.190 cm3/g. Surface characterization showed that chemical activation with H3PO4 results in the acidic character of the adsorbents surface, whereas products of pyrolysis and especially physical activation show strongly alkaline surface properties. All the adsorbents were used for methylene blue and iodine adsorption from the aquatic environment. To understand the nature of the sorption process, the Langmuir, Freundlich and Temkin isotherm models were employed. The Langmuir model best described the experimental results, and the maximum sorption capacity calculated for this model reached 164.14 mg of methylene blue per gram of adsorbent. In case of iodine removal, the maximum capacity reached 948.00 mg/g. The research carried out for the biochars prepared via conventional pyrolysis showed that the value of their heat of combustion varies in the range from 21.74 to 30.27 MJ/kg, so they can be applied as the renewable fuels.
Electrochemical Enzyme Sensor Based on the Two-Dimensional Metal–Organic Layers Supported Horseradish Peroxidase
Authors: Xiong Yu , Wang Chao , Wu YuanFei , Luo Chunhua , Zhan Dongping , Wang Shizhen
Published: December 2022

Metal–organic frames (MOFs) have recently been used to support redox enzymes for highly sensitive and selective chemical sensors for small biomolecules such as oxygen (O2), hydrogen peroxide (H2O2), etc. However, most MOFs are insulative and their three-dimensional (3D) porous structures hinder the electron transfer pathway between the current collector and the redox enzyme molecules. In order to facilitate electron transfer, here we adopt two-dimensional (2D) metal–organic layers (MOLs) to support the HRP molecules in the detection of H2O2. The correlation between the current response and the H2O2 concentration presents a linear range from 7.5 μM to 1500 μM with a detection limit of 0.87 μM (S/N = 3). The sensitivity, reproducibility, and stability of the enzyme sensor are promoted due to the facilitated electron transfer.
Resilience of Stevia rebaudiana (Bertoni) Bertoni in the Underwater Biospheres of Nemo’s Garden®: Adaptation to New Cultivation Systems
Authors: Ascrizzi Roberta , De Leo Marinella , Pistelli Laura , Giuliani Claudia , Pieracci Ylenia , Ruffoni Barbara , Mascarello Carlo , Fico Gelsomina , Flamini Guido , Pistelli Luisa
Published: December 2022

The Nemo’s Garden® project is an alternative production system for areas with scarce cultivable land but significant presence of water; thus, it is an interesting intervention to address the climate crisis. This work aimed to evaluate the micromorphological, biochemical, and phytochemical characteristics of Stevia rebaudiana (Bertoni) Bertoni grown underwater compared to the terrestrial specimens. The micromorphological analyses, performed on the leaves using light microscopy, fluorescence microscopy, and scanning electron microscopy, evidenced a general uniformity of the trichome morphotype and distribution pattern. The histochemical investigation indicated the simultaneous presence of terpenes and polyphenols in the trichome secreted material from the underwater samples and a prevailing polyphenolic content in the terrestrial specimens; this was also confirmed by biochemical analyses (26.6 mg GAE/g DW). The characterization of non-volatile components, performed using HPLC–MS, showed similar chemical profiles in all the samples, which were characterized by phenolic compounds and steviol glycosides. The volatile compounds, evaluated using HS-SPME coupled with GC–MS, showed sesquiterpene hydrocarbons as the main class in all the analyzed samples (80.1–93.9%). However, the control plants were characterized by a higher content of monoterpene hydrocarbons (12.1%). The underwater biosphere environment did not alter S. rebaudiana micro-morphological characters, although slight qualitative changes were evidenced for the compounds produced as a response to the growth conditions.
Development of a SPE-LC-MS Method for the Quantitation of Palbociclib and Abemaciclib in Human Plasma
Authors: Calucică Daniela Maria , Manda Costel-Valentin , Găman Amelia Maria , Răileanu Ștefan , Stanca Liliana , Popescu Monica Denisa Elena , Mateescu Olivia Garofița , Biță Andrei , Croitoru Octavian , Neamțu Simona-Daniela
Published: December 2022

Palbociclib and abemaciclib are two cyclin-dependent kinases 4 and 6 used for breast cancer treatment. Levels of these medicines present a significant interindividual variability, so monitoring those concentrations might be necessary in therapy. Most of the methods presented so far in the literature use simple protein precipitation of plasma proteins as sample preparation method followed by direct injection of the supernatant into the LC instrument, preceded or not by a simple filtration step. Within that approach, the probability of injecting proteins in the chromatographic system is increased. With the purpose of obtaining a cleaner extract of the drugs, we developed and validated a simple and accurate LC-MS method for determining palbociclib and abemaciclib in human plasma. Solid phase extraction (SPE) using Oasis PRiME HLB® cartridges was used for plasma sample preparation. The method provided clean extracts with a recovery extraction higher than 85% for both compounds. Separation was achieved by high-performance liquid chromatography (HPLC), using a C18 (4.6 × 50 mm) column, with a gradient elution of ammonium acetate/acetic acid-acetonitrile as the mobile phase. Detection was performed by mass spectrometry (MS) in single ion recording (SIR) mode. Intra-day and inter-day precision data for both analytes were 3.8–7.2% and 3.6–7.4%, respectively. Calibration curves were both linear between 2 and 400 ng/mL with a correlation coefficient higher than 0.998. The LC-MS method can be used to quantify the drugs in human plasma in routine analysis. The method proved to be useful in determining real plasma levels in patients involved in cancer therapy. Drug concentrations were determined in a 10 min run-time, including re-equilibration of the column.