bluuebunny/crossref_metadata_2025 huggingface dataset:
Glass Fiber Reinforced Concrete as a Durable and Enhanced Material for Structural and Architectural Elements in Smart City—A Review
Authors: Blazy Julia , Blazy Rafał , Drobiec Łukasz
Published: April 2022

The article highlights that glass fiber reinforced concretes (GFRC) can meet the requirements of Smart City better than ordinary concretes. The comprehensive discussion on GFRC composition is presented together with the review of glass fibers’ influence on various concrete properties. First of all, because of their bridging abilities, they can limit the width, length, and total area of cracks. Additionally, GFRC are characterized by enhanced tensile, flexural, and splitting strength; impact, abrasion, spalling, fire, and freeze-thaw resistance as well as ductility, toughness, and permeability. All of this positively influences the mechanical behavior, durability, and corrosion resistance of concrete elements. Moreover, decreased thermal conductivity allows for better energy performance from the building’s point of view. This results in cheaper structures both in manufacturing and maintaining even though GFRC are more expensive materials. However, mechanical properties enhance as long as sufficient workability and uniform fiber distribution are assured. From the environmental point of view, GFRC are eco-friendlier materials than ordinary concretes since their application can decrease the emission of CO2 by 17%. The article also describes the GFRC application fields and emphasizes the possibility of the creation of not only structural elements mainly intended for load transferring but also elements accompanying the building process, as well as elements of small architecture that make public spaces more attractive, durable, and safer. Owing to greater design and shaping freedom, GFRC can also better fulfill the needs of habitants of Smart City.
Synthesis and Properties Comparison of Low Dielectric Silicon Containing Polyimides
Authors: Chen Yuwei , Liu Yidong , Min Yonggang
Published: April 2022

Recent studies have shown that the introduction of silicon can effectively improve the dielectric properties of polyimide (PI), and the introduction of a silicon–oxygen bond can increase the flexibility of the PI molecular structure, which is conducive to reducing the moisture absorption rate of PI materials. In this experiment, 1,3-bis(3-aminopropyl)-1,1,3,3-tetramethyl disiloxane (DSX) was mixed with 4,4′-diaminodiphenyl ether (ODA) in different proportions. A series of PI films containing silicon was obtained by random polymerization with pyromellitic dianhydride (PMDA), 3,3′,4,4′-diphenylketotetrahedral anhydride (BTDA) and biphenyl dianhydride (BPDA), and then tetrad copolymerization with three kinds of dianhydrides. At the same time, the PI structures were put into calculation software to obtain the simulated polarization results, and then the films were characterized by various properties. The results showed that the characterization results were consistent with that of simulation, and the best overall PI formula was when the ratio of diamines was 1:9 and mixed with PMDA. The performance data were as follows: the vitrification temperature was about 320 °C, T5 was 551 °C, water absorption was 1.56%, dielectric constant (Dk) was 2.35, dielectric loss (Df) was 0.007, tensile strength was 70 MPa and elongation at break was 10.2%.
The Role of the Built-In Electric Field in Recombination Processes of GaN/AlGaN Quantum Wells: Temperature- and Pressure-Dependent Study of Polar and Non-Polar Structures
Authors: Koronski Kamil , Korona Krzysztof P. , Kryvyi Serhii , Wierzbicka Aleksandra , Sobczak Kamil , Krukowski Stanislaw , Strak Pawel , Monroy Eva , Kaminska Agata
Published: April 2022

In this paper, we present a comparative analysis of the optical properties of non-polar and polar GaN/AlGaN multi-quantum well (MQW) structures by time-resolved photoluminescence (TRPL) and pressure-dependent studies. The lack of internal electric fields across the non-polar structures results in an improved electron and hole wavefunction overlap with respect to the polar structures. Therefore, the radiative recombination presents shorter decay times, independent of the well width. On the contrary, the presence of electric fields in the polar structures reduces the emission energy and the wavefunction overlap, which leads to a strong decrease in the recombination rate when increasing the well width. Taking into account the different energy dependences of radiative recombination in non-polar and polar structures of the same geometry, and assuming that non-radiative processes are energy independent, we attempted to explain the ‘S-shape’ behavior of the PL energy observed in polar GaN/AlGaN QWs, and its absence in non-polar structures. This approach has been applied previously to InGaN/GaN structures, showing that the interplay of radiative and non-radiative recombination processes can justify the ‘S-shape’ in polar InGaN/GaN MQWs. Our results show that the differences in the energy dependences of radiative and non-radiative recombination processes cannot explain the ‘S-shape’ behavior by itself, and localization effects due to the QW width fluctuation are also important. Additionally, the influence of the electric field on the pressure behavior of the investigated structures was studied, revealing different pressure dependences of the PL energy in non-polar and polar MQWs. Non-polar MQWs generally follow the pressure dependence of the GaN bandgap. In contrast, the pressure coefficients of the PL energy in polar QWs are highly reduced with respect to those of the bulk GaN, which is due to the hydrostatic-pressure-induced increase in the piezoelectric field in quantum structures and the nonlinear behavior of the piezoelectric constant.
Binary Binder for Cf/C-SiC Composites with Enhanced Mechanical Property
Authors: Liu Yun , Ma Long , Dong Runa , Cui Kexin , Hou Yongzhao , Yang Wen , Liu Yeqing , Zhong Cheng , Wen Guangwu , Zhang Lijuan
Published: April 2022

Cf/C-SiC composites have become the preferred material for high-temperature load-bearing applications because of their low density, high strength, and excellent thermal-physical properties. Due to the composite’s poor sintering performance, the sintering temperature and pressure required for the preparation of Cf/C-SiC by traditional methods are also relatively high, which limits its engineering application. Herein, based on the precursor-derived ceramic route and C/C composites material preparation process, a binary binder (coal pitch and polysilylacetylene) is developed, which combines a carbon source, SiC precursor, and semi-ceramic SiC filler organically. Then, the SiC phase was successfully introduced into C/C composites by the slurry impregnation-hot pressing sintering method. The prepared Cf/C-SiC composites showed good mechanical properties, with a density of 1.53 g/cm3 and a bending strength of 339 ± 21 MPa. Moreover, the effects of the binary binder on the microstructure, density, and mechanical properties of Cf/C-SiC composites were investigated. This work provides a novel and effective approach to fabricating Cf/C-SiC composites with low density and high strength.
Effect of Kaolin Geopolymer Ceramics Addition on the Microstructure and Shear Strength of Sn-3.0Ag-0.5Cu Solder Joints during Multiple Reflow
Authors: Zaimi Nur Syahirah Mohamad , Salleh Mohd Arif Anuar Mohd , Abdullah Mohd Mustafa Al-Bakri , Nadzri Nur Izzati Muhammad , Sandu Andrei Victor , Vizureanu Petrica , Ramli Mohd Izrul Izwan , Nogita Kazuhiro , Yasuda Hideyuki , Sandu Ioan Gabriel
Published: April 2022

Solder interconnection in three-dimensional (3D) electronic packaging is required to undergo multiple reflow cycles of the soldering process. This paper elucidates the effects of multiple reflow cycles on the solder joints of Sn-3.0Ag-0.5Cu (SAC305) lead (Pb)-free solder with the addition of 1.0 wt.% kaolin geopolymer ceramics (KGC). The samples were fabricated using powder metallurgy with the hybrid microwave sintering method. Apart from using conventional cross-sectioned microstructure imaging, advanced synchrotron real-time in situ imaging was used to observe primary IMC formation in SAC305-KGC solder joints subjected to multiple reflow soldering. The addition of KGC particles in SAC305 suppressed the Cu6Sn5 IMC’s growth as primary and interfacial layers, improving the shear strength after multiple reflow soldering. The growth rate constant for the interfacial Cu6Sn5 IMC was also calculated in this study. The average growth rate of the primary Cu6Sn5 IMCs decreased from 49 µm/s in SAC305 to 38 µm/s with the addition of KGC particles. As a result, the average solidified length in the SAC305-KGC is shorter than SAC305 for multiple reflow soldering. It was also observed that with KGC additions, the growth direction of the primary Cu6Sn5 IMC in SAC305 changed from one growth to two growth directions. The observed results can be attributed to the presence of KGC particles both at grains of interfacial Cu6Sn5 IMCs and at the surface of primary Cu6Sn5 IMC.
Surface Interactions between Ketoprofen and Silica-Based Biomaterials as Drug Delivery System Synthesized via Sol–Gel: A Molecular Dynamics Study
Authors: Raffaini Giuseppina , Catauro Michelina
Published: April 2022

Biomaterial-based drug delivery systems for a controlled drug release are drawing increasing attention thanks to their possible pharmaceutical and biomedical applications. It is important to control the local administration of drugs, especially when the drug exhibits problems diffusing across biological barriers. Thus, in an appropriate concentration, it would be released in situ, reducing side effects due to interactions with the biological environment after implantation. A theoretical study based on Molecular Mechanics and Molecular Dynamics methods is performed to investigate possible surface interactions between the amorphous SiO2 surface and the ketoprofen molecules, an anti-inflammatory drug, considering the role of drug concentration. These theoretical results are compared with experimental data obtained by analyzing, through Fourier transform infrared spectroscopy (FT-IR), the interaction between the SiO2 amorphous surface and two percentages of the ketoprofen drug entrapped in a silica matrix obtained via the sol–gel method and dried materials. The loaded drug in these amorphous bioactive material forms hydrogen bonds with the silica surface, as found in this theoretical study. The surface interactions are essential to have a new generation of biomaterials not only important for biocompatibility, with specific structural and functional properties, but also able to incorporate anti-inflammatory agents for release into the human body.
Numerical Assessment of Dipole Interaction with the Single-Phase Nanofluid Flow in an Enclosure: A Pseudo-Transient Approach
Authors: Ayub Rashid , Ahmad Shabbir , Ahmad Sohail , Akhtar Yasmeen , Alam Mohammad Mahtab , Mahmoud Omar
Published: April 2022

Nanofluids substantially enhance the physical and thermal characteristics of the base or conducting fluids specifically when interacting with the magnetic field. Several engineering processes like geothermal energy extraction, metal casting, nuclear reactor coolers, nuclear fusion, magnetohydrodynamics flow meters, petrochemicals, and pumps incorporate magnetic field interaction with the nanofluids. On the other hand, an enhancement in heat transfer due to nanofluids is essentially required in various thermal systems. The goal of this study is to figure out that how much a magnetic field affects nanofluid flow in an enclosure because of a dipole. The nanofluid is characterized using a single-phase model, and the governing partial differential equations are computed numerically. A Pseudo time based numerical algorithm is developed to numerically solve the problem. It can be deduced that the Reynolds number and the magnetic parameter have a low effect on the Nusselt number and skin friction. The Nusselt number rises near the dipole location because of an increase in the magnetic parameter Mn and the Reynolds number Re. The imposed magnetic field alters the region of high temperature nearby the dipole, while newly generated vortices rotate in alternate directions. Furthermore, nanoparticle volume fraction causes a slight change in the skin friction while it marginally reduces the Nusselt number.
Probabilistic Assessment of the Dynamic Viscosity of Self-Compacting Steel-Fiber Reinforced Concrete through a Micromechanical Model
Authors: De La Rosa Ángel , Ruiz Gonzalo , Castillo Enrique , Moreno Rodrigo
Published: April 2022

This article develops a probabilistic approach to a micromechanical model to calculate the dynamic viscosity in self-compacting steel-fiber reinforced concrete (SCSFRC), which implies a paradigm shift in the approach of the deterministic models used. It builds on a previous work by the authors in which Bayesian analysis is applied to rheological micromechanical models in cement paste, self-compacting mortar, and self-compacting concrete. As a consequence of the varied characteristics of the particles in these suspensions (in terms of materials, shapes, size distributions, etc.), as well as their random nature, it seems appropriate to study these systems with probabilistic models. The Bayesian analysis, thorough Markov Chain Monte Carlo and Gibbs Sampling methods, allows the conversion of parametric-deterministic models into parametric-probabilistic models, which results in enrichment in engineering and science. The incorporation of steel fibers requires a new term in the model to account for their effect on the dynamic viscosity of SCSFRC, and this new term is also treated here with the Bayesian approach. The paper uses an extensive collection of experimental data to obtain the probability density functions of the parameters for assessing the dynamic viscosity in SCSFRC. The results obtained with these parameters’ distributions are much better than those calculated with the theoretical values of the parameters, which indicates that Bayesian methods are appropriated to respond to questions in complex systems with complex models.
Evaluation of the Mechanical Properties and Drilling of Glass Bead/Fiber-Reinforced Polyamide 66 (PA66)-Based Hybrid Polymer Composites
Authors: Demirsöz Recep , Yaşar Nafiz , Korkmaz Mehmet Erdi , Günay Mustafa , Giasin Khaled , Pimenov Danil Yurievich , Aamir Muhammad , Unal Huseyin
Published: April 2022

In this study, mechanical testing of glass bead (GB), glass fiber (GF), and hybrid (GB/GF) composites was carried out. Following that, drilling tests were undertaken on glass bead/fiber-reinforced hybrid Polyamide 66 (PA66) polymer composites. The purpose of this study is to determine the mechanical properties of the cutting elements and the effect of cutting parameters (spindle speed and feed rate) and reinforcement ratios on thrust force and surface roughness (Ra). The contribution of the cutting parameters to the investigated outcomes was determined using statistical analysis. Optical microscopy and scanning electron microscopy (SEM) was used to inspect the hole quality and damage mechanisms. The results revealed that the feed rate was the most contributing factor to thrust force (96.94%) and surface roughness (63.59%). Furthermore, in comparison to other hybrid composites, the lowest Ra value was obtained as 0.95 µm in samples containing 30% GB, while the Ra value was 1.04 µm in samples containing 10% GF + 20% GB. Polymer PA reinforced with 30% GF had the highest strength, modulus of elasticity, impact strength, and hardness.
Multi-Material Topology Optimization of Thermo-Elastic Structures with Stress Constraint
Authors: Chen Jianliang , Zhao Qinghai , Zhang Liang
Published: April 2022

This paper proposes a multi-material topology optimization formulation for thermo-elastic structures considering coupled mechanical and uniform thermal loads. The ordered-SIMP multiple materials interpolation model is introduced, combined with examples considering structural volume minimization under stress constraints. The p-norm function with the adjusted coefficient was adopted to measure the global maximum stress. The adjoint variable method is presented to discuss the sensitivity of stress constraints, and the method of moving asymptotes (MMA) is utilized to update the design variables. The results demonstrate that clear topologies are obtained for complicated multiple material combinations with various temperature values. Meanwhile, the optimized configuration with stress constraints has clear sensitivity to uniform temperature variations. Therefore, the proposed model demonstrates the necessity of a thermo-elastic model influenced by temperature in optimization.
New Sampling Expansion Related to Derivatives in Quaternion Fourier Transform Domain
Authors: Saima Siddiqui , Li Bingzhao , Adnan Samad Muhammad
Published: April 2022

The theory of quaternions has gained a firm ground in recent times and is being widely explored, with the field of signal and image processing being no exception. However, many important aspects of quaternionic signals are yet to be explored, particularly the formulation of Generalized Sampling Expansions (GSE). In the present article, our aim is to formulate the GSE in the realm of a one-dimensional quaternion Fourier transform. We have designed quaternion Fourier filters to reconstruct the signal, using the signal and its derivative. Since derivatives contain information about the edges and curves appearing in images, therefore, such a sampling formula is of substantial importance for image processing, particularly in image super-resolution procedures. Moreover, the presented sampling expansion can be applied in the field of image enhancement, color image processing, image restoration and compression and filtering, etc. Finally, an illustrative example is presented to demonstrate the efficacy of the proposed technique with vivid simulations in MATLAB.
A Comparison Study of the Classical and Modern Results of Semi-Local Convergence of Newton-Kantorovich Iterations
Authors: Regmi Samundra , Argyros Ioannis K. , George Santhosh , Argyros Christopher I.
Published: April 2022

There are a plethora of semi-local convergence results for Newton’s method (NM). These results rely on the Newton–Kantorovich criterion. However, this condition may not be satisfied even in the case of scalar equations. For this reason, we first present a comparative study of established classical and modern results. Moreover, using recurrent functions and at least as small constants or majorant functions, a finer convergence analysis for NM can be provided. The new constants and functions are specializations of earlier ones; hence, no new conditions are required to show convergence of NM. The technique is useful on other iterative methods as well. Numerical examples complement the theoretical results.
Global Dynamics of a Predator–Prey Model with Fear Effect and Impulsive State Feedback Control
Authors: Su Yangyang , Zhang Tongqian
Published: April 2022

In this paper, a predator–prey model with fear effect and impulsive state control is proposed and analyzed. By constructing an appropriate Poincaré map, the dynamic properties of the system, including the existence, nonexistence, and stability of periodic solutions are studied. More specifically, based on the biological meaning, the pulse and the phase set are firstly defined in different regions as well as the corresponding Poincaré map. Subsequently, the properties of the Poincaré map are analyzed, and the existence of a periodic solution for the system is investigated according to the properties of the Poincaré map. We found that the existence of the periodic solution for the system completely depends on the property of the Poincaré map. Finally, several examples containing numerical simulations verify the obtained theoretical result.
Predicting Stock Price Changes Based on the Limit Order Book: A Survey
Authors: Zaznov Ilia , Kunkel Julian , Dufour Alfonso , Badii Atta
Published: April 2022

This survey starts with a general overview of the strategies for stock price change predictions based on market data and in particular Limit Order Book (LOB) data. The main discussion is devoted to the systematic analysis, comparison, and critical evaluation of the state-of-the-art studies in the research area of stock price movement predictions based on LOB data. LOB and Order Flow data are two of the most valuable information sources available to traders on the stock markets. Academic researchers are actively exploring the application of different quantitative methods and algorithms for this type of data to predict stock price movements. With the advancements in machine learning and subsequently in deep learning, the complexity and computational intensity of these models was growing, as well as the claimed predictive power. Some researchers claim accuracy of stock price movement prediction well in excess of 80%. These models are now commonly employed by automated market-making programs to set bids and ask quotes. If these results were also applicable to arbitrage trading strategies, then those algorithms could make a fortune for their developers. Thus, the open question is whether these results could be used to generate buy and sell signals that could be exploited with active trading. Therefore, this survey paper is intended to answer this question by reviewing these results and scrutinising their reliability. The ultimate conclusion from this analysis is that although considerable progress was achieved in this direction, even the state-of-art models can not guarantee a consistent profit in active trading. Taking this into account several suggestions for future research in this area were formulated along the three dimensions: input data, model’s architecture, and experimental setup. In particular, from the input data perspective, it is critical that the dataset is properly processed, up-to-date, and its size is sufficient for the particular model training. From the model architecture perspective, even though deep learning models are demonstrating a stronger performance than classical models, they are also more prone to over-fitting. To avoid over-fitting it is suggested to optimize the feature space, as well as a number of layers and neurons, and apply dropout functionality. The over-fitting problem can be also addressed by optimising the experimental setup in several ways: Introducing the early stopping mechanism; Saving the best weights of the model achieved during the training; Testing the model on the out-of-sample data, which should be separated from the validation and training samples. Finally, it is suggested to always conduct the trading simulation under realistic market conditions considering transactions costs, bid–ask spreads, and market impact.
Comparison of HP Filter and the Hamilton’s Regression
Authors: Dritsaki Melina , Dritsaki Chaido
Published: April 2022

In this paper we examine if the use of Hamilton’s regression filter significantly modifies the cyclical components concerning unemployment in Greece compared with those using the Hodrick–Prescott double filter (HP). Hamilton suggested the use of a regression filter in order to overcome some of the drawbacks of the HP filter, which contains the presence of false cycles, the bias in the end of the sample, and the ad-hoc assumptions for the parameters’ smoothing. Thus, our paper examines two widely used detrending methods for the extraction of cyclical components, including techniques of deterministic detrending as well as stochastic detrending. Using quarterly data for the unemployment of Greece in a macroeconomic model decomposition, we indicate that trend components and cycle components of Hamilton’s filter regression led to significantly larger cycle volatilities than those from the HP filter. The dynamic forecasting in the sample, occurred both with autoregressive forecasting, that yields steady forecasts for a wide variety of non-stationary procedures, and with the HP filter, along with its constraints at the end of the time series. The results of the paper showed that the dynamic forecasting of the HP filter is better than that of Hamilton’s in all assessment measures.
Peripheral Neuropathy in Patients Recovering from Severe COVID-19: A Case Series
Authors: Balbi Pietro , Saltalamacchia Annamaria , Lullo Francesco , Fuschillo Salvatore , Ambrosino Pasquale , Moretta Pasquale , Lanzillo Bernardo , Maniscalco Mauro
Published: April 2022

Background and Objectives: Neurological manifestations have been reported in a significant proportion of coronavirus disease 2019 (COVID-19) patients. We aimed to evaluate the prevalence and severity of peripheral nervous system (PNS) involvement in a large group of convalescent COVID-19 patients undergoing in-hospital multidisciplinary rehabilitation. Materials and Methods: Convalescent COVID-19 patients admitted to a Pulmonary Rehabilitation Unit were consecutively screened for inclusion within 48 h of discharge from an acute care setting. All included patients underwent electrophysiological examinations. Results: Among 102 enrolled patients (mean age 62.0 years, 82.4% males), PNS electrophysiological alterations were detected in 42.2%. Mononeuropathies exclusively involving the peroneal nerve were observed in 8.8% (n = 9), while multiple mononeuropathies were similarly reported in nine patients (8.8%). A symmetric sensorimotor polyneuropathy was documented in 24.5% of participants (n = 25). A significant difference was found for exercise capacity and pulmonary function in post hoc comparisons between the three study groups. Conclusions: The risk of neuropathy in the convalescent phase of COVID-19 is relevant. This should be considered when planning multidisciplinary rehabilitation strategies.
External Validation of a Convolutional Neural Network for IDH Mutation Prediction
Authors: Hrapșa Iona , Florian Ioan , Șușman Sergiu , Farcaș Marius , Beni Lehel , Florian Ioan
Published: April 2022

Background and Objectives: The IDH (isocitrate dehydrogenase) status represents one of the main prognosis factors for gliomas. However, determining it requires invasive procedures and specialized surgical skills. Medical imaging such as MRI is essential in glioma diagnosis and management. Lately, fields such as Radiomics and Radiogenomics emerged as pertinent prediction tools for extracting molecular information out of medical images. These fields are based on Artificial Intelligence algorithms that require external validation in order to evaluate their general performance. The aim of this study was to provide an external validation for the algorithm formulated by Yoon Choi et al. of IDH status prediction using preoperative common MRI sequences and patient age. Material and Methods: We applied Choi’s IDH status prediction algorithm on T1c, T2 and FLAIR preoperative MRI images of gliomas (grades WHO II-IV) of 21 operated adult patients from the Neurosurgery clinic of the Cluj County Emergency Clinical Hospital (CCECH), Cluj-Napoca Romania. We created a script to automate the testing process with DICOM format MRI sequences as input and IDH predicted status as output. Results: In terms of patient characteristics, the mean age was 48.6 ± 15.6; 57% were female and 43% male; 43% were IDH positive and 57% IDH negative. The proportions of WHO grades were 24%, 14% and 62% for II, III and IV, respectively. The validation test achieved a relative accuracy of 76% with 95% CI of (53%, 92%) and an Area Under the Curve (AUC) through DeLong et al. method of 0.74 with 95% CI of (0.53, 0.91) and a p of 0.021. Sensitivity and Specificity were 0.78 with 95% CI of (0.45, 0.96) and 0.75 with 95% CI of (0.47, 0.91), respectively. Conclusions: Although our results match the external test the author made on The Cancer Imaging Archive (TCIA) online dataset, performance of the algorithm on external data is still not high enough for clinical application. Radiogenomic approaches remain a high interest research field that may provide a rapid and accurate diagnosis and prognosis of patients with intracranial glioma.
Synthesis of Natural Nano-Hydroxyapatite from Snail Shells and Its Biological Activity: Antimicrobial, Antibiofilm, and Biocompatibility
Authors: Ahmed Hanaa Y. , Safwat Nesreen , Shehata Reda , Althubaiti Eman Hillal , Kareem Sayed , Atef Ahmed , Qari Sameer H. , Aljahani Amani H. , Al-Meshal Areej Suliman , Youssef Mahmoud , Sami Rokayya
Published: April 2022

Hydroxyapatite nanoparticles (HAn) have been produced as biomaterial from biowaste, especially snail shells (Atactodea glabrata). It is critical to recycle the waste product in a biomedical application to overcome antibiotic resistance as well as biocompatibility with normal tissues. Moreover, EDX, TEM, and FT-IR analyses have been used to characterize snail shells and HAn. The particle size of HAn is about 15.22 nm. Furthermore, higher inhibitory activity was observed from HAn than the reference compounds against all tested organisms. The synthesized HAn has shown the lowest MIC values of about 7.8, 0.97, 3.9, 0.97, and 25 µg/mL for S. aureus, B. subtilis, K. pneumonia, C. albicans, and E. coli, respectively. In addition, the HAn displayed potent antibiofilm against S. aureus and B. subtilis. According to the MTT, snail shell and HAn had a minor influence on the viability of HFS-4 cells. Consequently, it could be concluded that some components of waste, such as snail shells, have economic value and can be recycled as a source of CaO to produce HAn, which is a promising candidate material for biomedical applications.
Semi-Industrial Production of a DPP-IV and ACE Inhibitory Peptide Fraction from Whey Protein Concentrate Hydrolysate by Electrodialysis with Ultrafiltration Membrane
Authors: Faucher Mélanie , Geoffroy Thibaud R. , Thibodeau Jacinthe , Gaaloul Sami , Bazinet Laurent
Published: April 2022

The separation by electrodialysis with ultrafiltration membranes (EDUF), at a semi-industrial scale, of a new whey protein hydrolysate obtained from a whey protein concentrate was assessed. After 6 h of treatment, more than 9 g of peptides were recovered in the peptide recovery fraction, for a recovery yield of 5.46 ± 0.56% and containing 18 major components. Among these components, positively charged peptides, such as ALPMHIR + PHMIR, LIVTQTMK and TKIPAVF, were present, and their relative abundances increased by nearly 1.25 X and up to 7.55 X. The presence of these peptides may be promising, as ALPMHIR has a strong activity against angiotensin-converting enzyme (ACE), and LIVTQTMK has structural properties that could interfere with dipeptidyl peptidase-IV (DPP-IV). Many neutral peptides were also recovered alongside those. Nevertheless, the inhibitory activity against DPP-IV and ACE increased from 2 X and 4 X, respectively, in the peptide recovery fraction compared to the initial hydrolysate, due to the improved content in bioactive peptides. Thus, this new hydrolysate is well-suited for the large-scale production of a peptide fraction with high bioactivities. Furthermore, what was achieved in this work came close to what could be achieved for the industrial production of a bioactive peptide fraction from whey proteins.
Effect of Ge Addition on Magnetic Properties and Crystallization Mechanism of FeSiBPNbCu Nanocrystalline Alloy with High Fe Content
Authors: Zhang Haijie , Bai Fushan , Dong Yaqiang , Xie Lei , Li Qiang , He Aina , Li Jiawei
Published: April 2022

In this work, new Ge-containing Fe-based nanocrystalline alloys with the composition of Fe80.2Si3B12-xP2Nb2Cu0.8Gex (x = 0, 1, 2 at.%) were developed, and the effects of Ge content on the magnetic and crystallization processes of the alloys were investigated. The addition of Ge extends the annealing window of the present Fe-based alloys, which reaches 173.6 K for the alloy of x = 2. The nanocrystalline alloy of x = 2, composed of dense and uniformly distributed α-Fe grains with an average grain size of 15.7 nm precipitated in the amorphous matrix, was obtained by conventional annealing treatment at a temperature of 843 K for 10 min, and this nanocrystalline alloy exhibited excellent magnetic properties with the Hc of 3 A/m and Bs of 1.65 T, which has great potential for industrial application. Non-isothermal crystallization kinetics studies show that the nucleation activation energy of the alloys gradually decreases with the increase in Ge content. The primary crystallization process is dominated by the direct growth of pre-existing nuclei in the as-spun alloy ribbons, and these pre-existing nuclei provide numerous heterogeneous nucleation sites to form dense and uniform α-Fe nanocrystals with a fine grain size, which leads to the excellent magnetic properties of the present Ge-containing Fe-based nanocrystalline alloys.
Independent and Interactive Effects of Genetic Background and Sex on Tissue Metabolomes of Adipose, Skeletal Muscle, and Liver in Mice
Authors: Wells Ann E. , Barrington William T. , Dearth Stephen , Milind Nikhil , Carter Gregory W. , Threadgill David W. , Campagna Shawn R. , Voy Brynn H.
Published: April 2022

Genetics play an important role in the development of metabolic diseases. However, the relative influence of genetic variation on metabolism is not well defined, particularly in tissues, where metabolic dysfunction that leads to disease occurs. We used inbred strains of laboratory mice to evaluate the impact of genetic variation on the metabolomes of tissues that play central roles in metabolic diseases. We chose a set of four common inbred strains that have different levels of susceptibility to obesity, insulin resistance, and other common metabolic disorders. At the ages used, and under standard husbandry conditions, these lines are not overtly diseased. Using global metabolomics profiling, we evaluated water-soluble metabolites in liver, skeletal muscle, and adipose from A/J, C57BL/6J, FVB/NJ, and NOD/ShiLtJ mice fed a standard mouse chow diet. We included both males and females to assess the relative influence of strain, sex, and strain-by-sex interactions on metabolomes. The mice were also phenotyped for systems level traits related to metabolism and energy expenditure. Strain explained more variation in the metabolite profile than did sex or its interaction with strain across each of the tissues, especially in liver. Purine and pyrimidine metabolism and pathways related to amino acid metabolism were identified as pathways that discriminated strains across all three tissues. Based on the results from ANOVA, sex and sex-by-strain interaction had modest influence on metabolomes relative to strain, suggesting that the tissue metabolome remains largely stable across sexes consuming the same diet. Our data indicate that genetic variation exerts a fundamental influence on tissue metabolism.
An Automated Room Temperature Flip-Chip Mounting Process for Hybrid Printed Electronics
Authors: Chen Zehua , Gengenbach Ulrich , Liu Xinnan , Scholz Alexander , Zimmermann Lukas , Aghassi-Hagmann Jasmin , Koker Liane
Published: April 2022

Printing technology and mounting technology enable the novel field of hybrid printed electronics. To establish a hybrid printed system, one challenge is that the applied mounting process meets the requirements of functional inks and substrates. One of the most common requirements is low process temperature. Many functional inks and substrates cannot withstand the high temperatures required by traditional mounting processes. In this work, a standardized interconnection and an automated bump-less flip-chip mounting process using a room temperature curing conductive adhesive are realised. With the proposed process, the conductive adhesive selected for the standardized interconnection can be dispensed uniformly, despite its increase of viscosity already during pot time. Electrical and mechanical performance of the interconnection are characterized by four terminal resistance measurement and shear test. The herein proposed automated process allows for fabrication of hybrid printed devices in larger batch sizes than manual assembly processes used beforehand and thus, more comprehensive evaluation of device parameters. This is successfully demonstrated in a first application, a novel hybrid printed security device. The room temperature mounting process eliminates any potentially damaging thermal influence on the performance of the printed circuits that might result from other assembly techniques like soldering.
Streptomyces sp. AN090126 as a Biocontrol Agent against Bacterial and Fungal Plant Diseases
Authors: Le Khanh Duy , Yu Nan Hee , Park Ae Ran , Park Dong-Jin , Kim Chang-Jin , Kim Jin-Cheol
Published: April 2022

Bacteria and fungi are major phytopathogens which substantially affect global agricultural productivity. In the present study, Streptomyces sp. AN090126, isolated from agricultural suppressive soil in Korea, showed broad-spectrum antagonistic activity against various phytopathogenic bacteria and fungi. In the 96-well plate assay, the fermentation filtrate of Streptomyces sp. AN090126 exhibited antimicrobial activity, with a minimum inhibitory concentration (MIC) of 0.63–10% for bacteria and 0.63–3.3% for fungi. The MIC of the partially purified fraction was 20.82–250 µg/mL for bacteria and 15.6–83.33 µg/mL for fungi. Gas chromatography–mass spectrometry (GC-MS) analysis revealed that AN090126 produced various volatile organic compounds (VOCs), including dimethyl sulfide and trimethyl sulfide, which inhibited the growth of pathogenic bacteria and fungi in in vitro VOC assays. In pot experiments, the fermentation broth of Streptomyces sp. AN090126 reduced tomato bacterial wilt caused by Ralstonia solanacearum, red pepper leaf spot caused by Xanthomonas euvesicatoria, and creeping bentgrass dollar spot caused by Sclerotinia homoeocarpa in a dose-dependent manner. Moreover, the secondary metabolites derived from this strain showed a synergistic effect with streptomycin sulfate against streptomycin-resistant Pectobacterium carotovorum subsp. carotovorum, the causative agent of Kimchi cabbage soft rot, in both in vitro and in vivo experiments. Therefore, Streptomyces sp. AN090126 is a potential biocontrol agent in controlling plant diseases caused by pathogenic bacteria and fungi, specifically by the streptomycin-resistant strains.
Effects of Artemisia macrocephala Jacquem on Memory Deficits and Brain Oxidative Stress in Streptozotocin-Induced Diabetic Mice
Authors: Bari Atiqul , Shah Syed Muhammad Mukarram , Al-Joufi Fakhria A. , Shah Syed Wadood Ali , Shoaib Mohammad , Shah Ismail , Zahoor Muhammad , Ahmed Muhammad Naeem , Ghias Mehreen , Shah Syed Muhammad Hassan , Khalil Atif Ali Khan
Published: April 2022

Different species of Artemisia have been reported to have therapeutic potential in treating various health disorders, including diabetes and memory dysfunction. The present study was planned to evaluate the effects of Artemisia macrocephala Jacquem crude extract and its subfractions as antiamnesic agents in streptozotocin-induced (STZ) diabetic mice. The in vivo behavioral studies were performed using the Y Maze test and novel object recognition test (NORT) test at doses of 100 and 200 mg/kg of crude extract and 75 and 150 mg/kg of fractions. The in vitro and ex vivo anticholinesterase activities, along with biochemical parameters (superoxide dismutase, catalase, glutathione and lipid peroxidation) in the brain, were evaluated. Blood glucose levels were monitored with a glucometer; crude extract and fractions reduced the glucose level considerably, with some differences in the extent of their efficacies. The crude extract and fractions demonstrated significant inhibitory activity against cholinesterases (AChE and BuChE) in vitro. Crude, chloroform and ethyl acetate extract were found to be more potent than the other fractions, with IC50 of Crd-Am = 116.36 ± 1.48 and 240.52 ± 1.35 µg/mL, Chl-Am = 52.68 ± 1.09 and 57.45 ± 1.39 µg/mL and Et-Am = 75.19 ± 1.02 and 116.58 ± 1.09 µg/mL, respectively. Oxidative stress biomarkers like superoxide dismutase, catalase and glutathione levels were elevated, whereas MDA levels were reduced by crude extract and all fractions with little difference in their respective values. The Y-maze test and novel object recognition test demonstrated declines in memory impairment in groups (n = 6) treated with crude extract and fractions as compared to STZ diabetic (amnesic) group. The most active fraction, Chl-Am, was also subjected to isolation of bioactive compounds; three compounds were obtained in pure state and designated as AB-I, AB-II and AB-III. Overall, the results of the study showed that Artemisia macrocephala Jacquem enhanced the memory impairment associated with diabetes, elevated acetylcholine levels and ameliorated oxidative stress. Further studies are needed to explore the beneficial role of the secondary metabolites isolated in the present study as memory enhancers. Toxicological aspects of the extracts are also important and need to be evaluated in other animal models.
Structure Elucidation of Triterpenoid Saponins Found in an Immunoadjuvant Preparation of Quillaja brasiliensis Using Mass Spectrometry and 1H and 13C NMR Spectroscopy
Authors: Wallace Federico , Fontana Carolina , Ferreira Fernando , Olivaro Cristina
Published: April 2022

An immunoadjuvant preparation (named Fraction B) was obtained from the aqueous extract of Quillaja brasiliensis leaves, and further fractionated by consecutive separations with silica flash MPLC and reverse phase HPLC. Two compounds were isolated, and their structures elucidated using a combination of NMR spectroscopy and mass spectrometry. One of these compounds is a previously undescribed triterpene saponin (Qb1), which is an isomer of QS-21, the unique adjuvant saponin employed in human vaccines. The other compound is a triterpene saponin previously isolated from Quillaja saponaria bark, known as S13. The structure of Qb1 consists of a quillaic acid residue substituted with a β-d-Galp-(1→2)-[β-d-Xylp-(1→3)]-β-d-GlcpA trisaccharide at C3, and a β-d-Xylp-(1→4)-α-l-Rhap-(1→2)-[α-l-Arap-(1→3)]-β-d-Fucp moiety at C28. The oligosaccharide at C28 was further substituted at O4 of the fucosyl residue with an acyl group capped with a β-d-Xylp residue.
Biomolecules from Plant Wastes Potentially Relevant in the Management of Irritable Bowel Syndrome and Co-Occurring Symptomatology
Authors: Balmus Ioana-Miruna , Copolovici Dana , Copolovici Lucian , Ciobica Alin , Gorgan Dragos Lucian
Published: April 2022

During and following the processing of a plant’s raw material, considerable amounts are wasted, composted, or redistributed in non-alimentary sectors for further use (for example, some forms of plant waste contribute to biofuel, bioethanol, or biomass production). However, many of these forms of waste still consist of critical bioactive compounds used in the food industry or medicine. Irritable bowel syndrome (IBS) is one of the most common functional gastrointestinal disorders. The primary treatment is based on symptomatology alleviation and controlled dietary management. Thus, this review aimed to describe the possible relevance of molecules residing in plant waste that can be used to manage IBS and co-occurring symptoms. Significant evidence was found that many forms of fruit, vegetable, and medicinal plant waste could be the source of some molecules that could be used to treat or prevent stool consistency and frequency impairments and abdominal pain, these being the main IBS symptoms. While many of these molecules could be recovered from plant waste during or following primary processing, the studies suggested that enriched food could offer efficient valorization and prevent further changes in properties or stability. In this way, root, stem, straw, leaf, fruit, and vegetable pomaces were found to consist of biomolecules that could modulate intestinal permeability, pain perception, and overall gastrointestinal digestive processes.
Interaction Structure and Affinity of Zwitterionic Amino Acids with Important Metal Cations (Cd2+, Cu2+, Fe3+, Hg2+, Mn2+, Ni2+ and Zn2+) in Aqueous Solution: A Theoretical Study
Authors: Liu Xinning , Wu Menghan , Li Chenchen , Yu Peng , Feng Shanshan , Li Yanwei , Zhang Qingzhu
Published: April 2022

Heavy metals are non-biodegradable and carcinogenic pollutants with great bio-accumulation potential. Their ubiquitous occurrence in water and soils has caused serious environmental concerns. Effective strategies that can eliminate the heavy metal pollution are urgently needed. Here the adsorption potential of seven heavy metal cations (Cd2+, Cu2+, Fe3+, Hg2+, Mn2+, Ni2+ and Zn2+) with 20 amino acids was systematically investigated with Density Functional Theory method. The binding energies calculated at B3LYP-D3/def2TZVP level showed that the contribution order of amino acid side chains to the binding affinity was carboxyl > benzene ring > hydroxyl > sulfhydryl > amino group. The affinity order was inversely proportional to the radius and charge transfer of heavy metal cations, approximately following the order of: Ni2+ > Fe3+ > Cu2+ > Hg2+ > Zn2+ > Cd2+ > Mn2+. Compared to the gas-phase in other researches, the water environment has a significant influence on structures and binding energies of the heavy metal and amino acid binary complexes. Collectively, the present results will provide a basis for the design of a chelating agent (e.g., adding carboxyl or a benzene ring) to effectively remove heavy metals from the environment.
Influence of Irradiance and Wavelength on the Antioxidant Activity and Carotenoids Accumulation in Muriellopsis sp. Isolated from the Antofagasta Coastal Desert
Authors: Diaz-MacAdoo Daniela , Mata Maria Teresa , Riquelme Carlos
Published: April 2022

Microalgae are a valuable natural resource for a variety of biocompounds such as carotenoids. The use of different light spectra and irradiance has been considered as a promising option to improve the production of these compounds. The objective of this study was to evaluate the influence of different wavelengths (white, red, and blue) and irradiances (80 and 350 µmol photons/m2/s) on the photosynthetic state, total carotenoids and lutein productivity (HPLC), lipids (Nile red method) and antioxidant activity (DPPH) of the microalgae Muriellopsis sp. (MCH-35). This microalga, which is a potential source of lutein, was isolated from the coastal desert of Antofagasta, Chile, and adapted to grow in seawater. The results indicate that the culture exposed to high-intensity red light showed the highest biomass yield (2.5 g/L) and lutein productivity (>2.0 mg L−1day−1). However, blue light was found to have a stimulating effect on the synthesis of lutein and other carotenoids (>0.8% dry wt). Furthermore, a direct relationship between lipid accumulation and high light intensity was evidenced. Finally, the highest antioxidant activity was observed with high-intensity white light, these values have no direct relationship with lutein productivity. Therefore, the findings of this study could be utilized to obtain biocompounds of interest by altering certain culture conditions during the large-scale cultivation of MCH-35.