bluuebunny/crossref_metadata_2025 huggingface dataset:
Optimization of the Post-Process Heat Treatment Strategy for a Near-α Titanium Base Alloy Produced by Laser Powder Bed Fusion
Authors: Fleißner-Rieger Christian , Pfeifer Tanja , Turk Christoph , Clemens Helmut
Published: January 2022

During the last decades, titanium alloys have been of great interest for lightweight applications due to their high strength in combination with a low material density. Current research activities focus on the investigation of near-α titanium alloys produced by laser powder bed fusion (LPBF). These alloys are known for their superior tensile strength and high creep resistance. This study focuses on the optimization of post-process heat treatments and the impact on tensile and creep strength of a LPBF produced Ti6242S alloy. Therefore, a variety of annealing steps were conducted to gain knowledge about the decomposition process of the non-equilibrium as-built microstructure and the arising influence on the mechanical properties. Components made of Ti6242S and produced by LPBF reveal an extraordinarily high ultimate tensile strength of about 1530 MPa at room temperature, but show a low elongation at fracture (A5 = 4.3%). Based on microstructure-property relationships, this study recommends precise heat treatments on how to improve the desired mechanical properties in terms of strength, ductility as well as creep resistance. Moreover, this study shows a triplex heat treatment, which enhances the elongation at fracture (A5) to 16.5%, while the ultimate tensile strength is still at 1100 MPa.
The Course and the Effects of Agricultural Biomass Pyrolysis in the Production of High-Calorific Biochar
Authors: Kazimierski Paweł , Januszewicz Katarzyna , Godlewski Wojciech , Fijuk Aleksander , Suchocki Tomasz , Chaja Patryk , Barczak Beata , Kardaś Dariusz
Published: January 2022

The thermal pyrolysis of agriculture biomass has been studied in a fixed-bed reactor, where the pyrolysis was conducted at a steady temperature of 800 °C. This work analyses the pyrolysis products of six agricultural wastes: pistachio husks, walnut husks, sunflower hulls, buckwheat husks, corncobs and coconut shells. The conducted research compared examples of large waste biomass streams from different parts of the world as a potential source of renewable energy. Additionally, the kinetics of the reaction with the activation energy were analyzed and calculated for all raw materials in pyrolysis process. Biochars are characterised by higher combustion heat in comparison to the raw material samples. The average value of the heat of combustion increased due to pyrolysis process from 10 MJ/kg, with minimal value of 2.7 MJ/kg (corncob) and maximum of 13.0 MJ/kg for coconut, which is also characterised by the maximal absolute combustion heating value (32.3 MJ/kg). The increase in calorific values varied from 15% to 172% (with 54% reference for wood chips), which indicates that charring is an effective method for increasing the energy concentration. The obtained biochar were compared with wood chips, which are widely used solid fuel of organic origin. The studied biomass-derived fuels are characterised by lower ash contribution than wood. An analogous observation was made for the obtained biochars, whose ash contribution was lower than for the chips in terms of both unit-mass and unit-combustion-heat. The main advantage of this method is the production of solid fuel from biomass, which increases the calorific value and bulk density of biochar in comparison to raw material.
Simulation of Electrical and Thermal Properties of Granite under the Application of Electrical Pulses Using Equivalent Circuit Models
Authors: Fukushima Kyosuke , Kabir Mahmudul , Kanda Kensuke , Obara Naoko , Fukuyama Mayuko , Otsuki Akira
Published: January 2022

Since energy efficiency in comminution of ores is as small as 1% using a mechanical crushing process, it is highly demanded to improve its efficiency. Using electrical impulses to selectively liberate valuable minerals from ores can be a solution of this problem. In this work, we developed a simulation method using equivalent circuits of granite to better understand the crushing process with high-voltage (HV) electrical pulses. From our simulation works, we calculated the electric field distributions in granite when an electrical pulse was applied. We also calculated other associated electrical phenomena such as produced heat and temperature changes from the simulation results. A decrease in the electric field was observed in the plagioclase with high electrical conductivity and void space. This suggests that the void volume in each mineral is important in calculating the electrical properties. Our equivalent circuit models considering both the electrical conductivity and dielectric constant of a granite can more accurately represent the electrical properties of granite under HV electric pulse application. These results will help us better understand the liberation of minerals from granite by electric pulse application.
Improving Polysaccharide-Based Chitin/Chitosan-Aerogel Materials by Learning from Genetics and Molecular Biology
Authors: Behr Matthias , Ganesan Kathirvel
Published: January 2022

Improved wound healing of burnt skin and skin lesions, as well as medical implants and replacement products, requires the support of synthetical matrices. Yet, producing synthetic biocompatible matrices that exhibit specialized flexibility, stability, and biodegradability is challenging. Synthetic chitin/chitosan matrices may provide the desired advantages for producing specialized grafts but must be modified to improve their properties. Synthetic chitin/chitosan hydrogel and aerogel techniques provide the advantages for improvement with a bioinspired view adapted from the natural molecular toolbox. To this end, animal genetics provide deep knowledge into which molecular key factors decisively influence the properties of natural chitin matrices. The genetically identified proteins and enzymes control chitin matrix assembly, architecture, and degradation. Combining synthetic chitin matrices with critical biological factors may point to the future direction with engineering materials of specific properties for biomedical applications such as burned skin or skin blistering and extensive lesions due to genetic diseases.
Superhydrophobic Coating Based on Porous Aluminum Oxide Modified by Polydimethylsiloxane (PDMS)
Authors: Olkowicz Klaudia , Buczko Zofia , Nasiłowska Barbara , Kowalczyk Kamil , Czwartos Joanna
Published: January 2022

The aim of this study was to obtain a superhydrophobic coating by modifying anodized aluminum using polydimethylsiloxane (PDMS). In order to obtain a superhydrophobic coating on an aluminum substrate, a multistage treatment was implemented. Specimens of aluminum were treated by abrasive blasting, anodization in sulfuric acid, impregnation by PDMS, rinsing in toluene to remove excess of PDMS, and curing. A rough surface with an additional low free energy layer on it resulted in a superhydrophobic effect. The coating obtained has an average contact angle of 159°. The specimens were tested in terms of durability in natural conditions. Additionally, anti-icing and anti-fouling properties were evaluated. The coating was compared with anodized aluminum obtained by a basic process.
Porous Glass Microspheres from Alkali-Activated Fiber Glass Waste
Authors: Mahmoud Mokhtar , Kraxner Jozef , Kaňková Hana , Hujová Miroslava , Chen Si , Galusek Dušan , Bernardo Enrico
Published: January 2022

Fiber glass waste (FGW) was subjected to alkali activation in an aqueous solution with different concentrations of sodium/potassium hydroxide. The activated materials were fed into a methane–oxygen flame with a temperature of around 1600 °C. X-ray diffraction analysis confirmed the formation of several hydrated compounds, which decomposed upon flame synthesis, leading to porous glass microspheres (PGMs). Pore formation was favored by using highly concentrated activating alkali solutions. The highest homogeneity and yield of PGMs corresponded to the activation with 9 M KOH aqueous solution.
Quantile Trend Regression and Its Application to Central England Temperature
Authors: Haupt Harry , Fritsch Markus
Published: January 2022

The identification and estimation of trends in hydroclimatic time series remains an important task in applied climate research. The statistical challenge arises from the inherent nonlinearity, complex dependence structure, heterogeneity and resulting non-standard distributions of the underlying time series. Quantile regressions are considered an important modeling technique for such analyses because of their rich interpretation and their broad insensitivity to extreme distributions. This paper provides an asymptotic justification of quantile trend regression in terms of unknown heterogeneity and dependence structure and the corresponding interpretation. An empirical application sheds light on the relevance of quantile regression modeling for analyzing monthly Central England temperature anomalies and illustrates their various heterogenous trends. Our results suggest the presence of heterogeneities across the considered seasonal cycle and an increase in the relative frequency of observing unusually high temperatures.
Understanding Prospective Teachers’ Task Design Considerations through the Lens of the Theory of Didactical Situations
Authors: Daher Wajeeh , Baya’a Nimer , Jaber Otman
Published: January 2022

Task design, in general, and task design in a technological environment, is attracting the attention of educational researchers. The present research investigates task design of prospective teachers in the Scratch programming environment. A total of twenty-three female prospective teachers participated in a professional development program. They were in their third academic year majoring in teaching mathematics and computer science in the middle school. The prospective teachers attempted to design mathematics-based programming problems. The present research utilizes the theory of didactical situations in mathematics, specifically the situation types, the paradoxes of the didactical contract and the situation components, to study the task design of the prospective teachers. It does that by focusing on one group of prospective teachers. The research results indicated that the prospective teachers were concerned mainly with the situation of information, situation of reference and situation of action. Doing so, they were concerned with the paradox of the said and the unsaid, the paradox of uncertainty, and the paradox of devolution. In addition, they took care of both algorithmic and creative reasoning. They also took care of students’ devolution, where this devolution was conditioned with following an institutionalization. They were also concerned with giving students autonomy and encouraging decision making regarding the solution of the problem. Furthermore, they planned to enable students’ control over their learning.
Multiobjective Optimization for Planning the Service Areas of Smart Parcel Locker Facilities in Logistics Last Mile Delivery
Authors: Che Zhen-Hua , Chiang Tzu-An , Luo Yun-Jhen
Published: January 2022

The planning of the location service areas of smart parcel locker facilities became a critical aspect of logistics last mile delivery. In e-commerce, the efficiency of delivering merchandise from retailer warehouses to customers determines the competitiveness of retailers and delivery operators. The considerable increases in e-commerce transactions and safety concerns under the COVID-19 (Coronavirus disease 2019) pandemic made home delivery services even more inefficient than before, which resulted in the considerable increase in social costs. In numerous countries, smart parcel lockers were adopted to increase delivery efficiency, decrease the risk of COVID-19 infection, and reduce the burden on society. This study proposed a multiobjective optimization mathematical model for investigating the planning of the location service areas of smart parcel locker facilities, and then the optimization mathematical model was solved using a combination of the Taguchi method (TA) and nondominant sorting genetic algorithm II (NSGA-II). Finally, this composite approach was applied to a case study in producing favorable solutions for facility location service area planning.
Tools for Correlation and Regression Analyses in Estimating a Functional Relationship of Digitalization Factors
Authors: Zemlyak Svetlana , Gusarova Olga , Khromenkova Galina
Published: January 2022

Digitalization processes affect all levels and spheres of human activities, from personal communications to public events. The widespread implementation of digital technologies has an ambiguous effect on the personal, social, and economic paths of modern society’s development. At the moment, there is no single approach to the estimation of digitalization’s impact, particularly on the financial and economic properties of a company. The objective of this study was to create multiple models for the assessment of digitalization’s impact on company performance. To accomplish this objective, the following steps were performed: conducting a literature survey on the experience with digital technologies’ implementation; selecting the most appropriate mathematical tools for correlation and regression analyses; determining a functional relationship between the factors and consequences of digitalization in terms of companies’ performance; identifying digitalization factors, risks, and their impact on the financial sustainability of companies; and creating a multiple regression model of the functional relationship between digitalization factors and the financial sustainability of companies. In the course of the study, a correlation analysis of the dependence of companies’ financial sustainability on a number of digitalization factors has been conducted, and different ways of using company performance data as effective features and predictive factors are offered. The article includes sampling data on the parameterization and quality evaluation of multiple regression models. The validity of the multiple models suggested was tested with actual statistical data obtained from 16 Russian companies. The application of the multiple regression model was devised to estimate digitalization’s impact on companies’ performance, and their financial sustainability can be seen as the most important practical implication of this study.
Numerical and Theoretical Stability Study of a Viscoelastic Plate Equation with Nonlinear Frictional Damping Term and a Logarithmic Source Term
Authors: Al-Gharabli Mohammad M. , Almahdi Adel M. , Noor Maher , Audu Johnson D.
Published: January 2022

This paper is designed to explore the asymptotic behaviour of a two dimensional visco-elastic plate equation with a logarithmic nonlinearity under the influence of nonlinear frictional damping. Assuming that relaxation function g satisfies g′(t)≤−ξ(t)G(g(t)), we establish an explicit general decay rates without imposing a restrictive growth assumption on the damping term. This general condition allows us to recover the exponential and polynomial rates. Our results improve and extend some existing results in the literature. We preform some numerical experiments to illustrate our theoretical results.
Successful Negative Pressure Therapy of Enteroatmospheric Fistula after Right Colectomy for Complicated Crohn’s Disease —A Proposal for a Three-Drain Wound-Separation Technique
Authors: Popivanov Georgi , Cirocchi Roberto , Penchev Dimitar , Kjossev Kirien , Konaktchieva Marina , Mutafchiyski Ventsislav
Published: January 2022

Enteroatmospheric fistulas (EAFs) are still the worst complication of the open abdomen. They lead to a significantly prolonged intensive care unit and hospital stay and to high mortality. Despite the various techniques described in the literature EAFs remain “a nightmare” for the patient, the surgeon, and the hospital. Here we describe a case of right colectomy for obstructing Crohn’s disease in a 26-year-old. On the 19th postoperative day, he developed a superficial EAF. Due to the frozen abdomen, neither resection of the anastomosis, nor implementation of the known techniques for treatment of EAFs were possible. This prompted us to modify the Pepe technique. The EAF was isolated from the upper and lower parts of the wound through deep-skin and subcutaneous sutures and the application of two small pieces of non-adherent plastic foil. The lower holes of a single drain, put through a piece of black foam, were placed over the fistula. The upper holes, which were enveloped with the foam, remained in contact with the wound. The drain was connected to a negative pressure of 125 mmHg. NPWT (negative pressure wound therapy) was also applied by two separate sponges and drains in the upper and lower part. The mainstay of EAF treatment is the isolation of the EAF from the abdominal cavity and subcutaneous tissue, supported by control of the sepsis and adequate nutrition. The proposed technique is applicable in cases with a single, superficial EAF on the background of the frozen abdomen with minimal lateral fascial retraction. As of today, due to the rarity of the condition and lack of randomized trials, EAFs still represents a unique challenge often requiring improvisation.
Acute Respiratory Failure, Ischemic Modifications on Electrocardiogram: Alternative Etiology—A Case of Morgagni Hernia
Authors: Szász Agnes Zsuzsánna , Székely-Vass Enikő Dalma , Lovász Gyopár Tunde , Magdás Annamária , Ferencz Loránd Jozsef
Published: January 2022

We discovered a rare pathology described in adulthood, followed by the development of a long asymptomatic evolution, which underlined the importance of multidisciplinary collaboration. We present the case of a 62-year-old female smoker patient, with a known previous medical history of chronic ischemic heart disease, hypertension, chronic obstructive pulmonary disease (COPD), gastric ulcer and gastritis. The patient was rushed to the emergency room (ER) with acute respiratory failure, chest discomfort, ankle and facial edema and a chest X-ray showing a right lower pulmonary lobe consolidation, with an alarming ischemic electrocardiogram (ECG) modification without increasing myocardial cytolysis indicators. This led our medical team to investigate a possible cardiovascular event that might have been in development. After immediate admission, thoracic computer tomography (CT) imaging was carried out, which found a Morgagni diaphragmatic hernia, containing adipose tissue and the hepatic flexure of the colon with approximate dimensions of 50/100 mm. We faced differential diagnostic problems. We knew the subject’s existing cardiac and chronic respiratory tract pathologies from their previous medical history; therefore, multiple investigations and check-ups were carried out. A chest CT and surgery intervention were needed to resolve this case. Subsequently, the acute respiratory failure and alarming ischemic ECG modification disappeared.
Identification of Antimycobacterial Natural Products from a Library of Marine Invertebrate Extracts
Authors: Acquah Kojo Sekyi , Beukes Denzil R. , Seldon Ronnett , Jordaan Audrey , Sunassee Suthananda N. , Warner Digby F. , Gammon David W.
Published: January 2022

Tuberculosis (TB) remains a public health crisis, requiring the urgent identification of new anti-mycobacterial drugs. We screened several organic and aqueous marine invertebrate extracts for their in vitro inhibitory activity against the causative organism, Mycobacterium tuberculosis. Here, we report the results obtained for 54 marine invertebrate extracts. The chemical components of two of the extracts were dereplicated, using 1H NMR and HR-LCMS with GNPS molecular networking, and these extracts were further subjected to an activity-guided isolation process to purify the bioactive components. Hyrtios reticulatus yielded heteronemin 1 and Jaspis splendens was found to produce the bengamide class of compounds, of which bengamides P 2 and Q 3 were isolated, while a new derivative, bengamide S 5, was putatively identified and its structure predicted, based on the similarity of its MS/MS fragmentation pattern to those of other bengamides. The isolated bioactive metabolites and semi-pure fractions exhibited M. tuberculosis growth inhibitory activity, in the range <0.24 to 62.50 µg/mL. This study establishes the bengamides as potent antitubercular compounds, with the first report of whole-cell antitubercular activity of bengamides P 2 and Q 3.
Ethnobotanical and Phytochemical Profiling of Medicinal Plants from Burkina Faso Used to Increase Physical Performance
Authors: Sama Hemayoro , Traoré Modeste , Guenné Samson , Séré Ibrahim , Hilou Adama , Dicko Mamoudou H.
Published: January 2022

Background: Some ergogenic medicinal plants are used in exercise and sport in Africa in order to increase sport performance. However, data on their composition and their possible impacts on health are limited. This study was initiated to provide ethnobotanical data on plants traditionally used to optimize physical performance and to perform a qualitative characterization of their main chemical groups. Methods: Ethnobotanical surveys in two communes (Dedougou and Nouna), of the region of Boucle du Mouhoun, Burkina Faso and phytochemical analyses of the most interesting plants were conducted. Results: A total of 50 respondents including traditional hunters dozo, farmers, healers, herbalists, marabouts, etc., were interviewed. Fifty-two species used in the optimization of exercise and sports have been identified. The most cited species were Cassia sieberiana, Tamarindus indica, Annona senegalensis, Gardenia sokotensis, Securidaca longepedunculata, and Ficus tonningii. These plants are known to prevent muscle and skeletal disorders, aches and pains, and mental disorders. The study identified several types of plants including those displaying stimulation, anxiolytic, sedative, adaptogenic, or erythropoietic activities. Phytochemical screening revealed the presence of phenolic compounds, alkaloids, terpenes, and steroids, which are similar molecules families of those of doping molecules. Additionally, TLC screening allowed the characterization of numerous terpene and flavonoid compounds including rutin. Conclusions: The possible structural similarity of the characterized chemical groups of these species with those of doping families raise concerns about the consequences of their consumption. However, the identification of the active molecules of these species remains to be performed in order to predict the real risks associated with their consumption.
A Novel Ocean Thermal Energy Driven System for Sustainable Power and Fresh Water Supply
Authors: Ma Qingfen , Zheng Yun , Lu Hui , Li Jingru , Wang Shenghui , Wang Chengpeng , Wu Zhongye , Shen Yijun , Liu Xuejin
Published: January 2022

The ocean thermal energy conversion (OTEC) is a potential substitute for traditional power plants in tropical islands and coastal regions. However, the OTEC power generation cycle has low thermal efficiency and the integrated utilization is imperative, in which an OTEC coupled with seawater desalination is the most attractive option. Membrane distillation (MD) has distinct advantages making itself a competitive process for seawater desalination, especially the feature that the drained warm seawater from the OTEC power plant can be recycled, improving the integrated output of the OTEC system. In this study, an innovative OTEC system coupling a power generation sub-cycle (PGC) and a water production sub-cycle (WPC) was proposed, composed of the upstream organic Rankine cycle and the downstream membrane distillation modules. The mass, energy and exergy balance of the individual equipment, the sub-cycles and the whole system were performed by constructing the corresponding balance models. The thermal dynamic parameters were calculated, and the performance of power generation and water production was predicted. The results showed that by coupling with the MD desalination, the thermal efficiency of the OTEC system can be greatly improved from 2.19% to 25.38% while the exergy efficiency changed little. For a 100 kW OTEC power generation cycle, the water production rate approached 58.874 t/d. In addition, the economic analysis based on the electricity and water sale was carried out, and the profit can be improved by extra water production, especially in the Hawaii and Rainbow Beach by nearly 20%.
Calibration of the Flow Curve Up to Large Strain Range by Incremental Sheet Forming Coupled with FEM Simulation
Authors: Kim Young-Suk , Tuan Pham-Quoc , Xiao Xiao , Kim Jin-jae
Published: January 2022

Conventionally, a stress–strain curve for sheet materials is defined by the uniaxial tensile test; however, it is limited by the necking phenomena. The stress–strain curve in the post-necking range is determined using common hardening equations, such as the Swift or Voce equation. Nevertheless, the accuracy of this flow curve in the extrapolation range is questionable. In this study, the inverse method using incremental sheet forming coupled with FEM simulation was used to calibrate the stress–strain curve up to a large strain range. In the incremental sheet forming experiment, the forming force was monitored in the whole process until fracture. Then, FEM simulation by ABAQUS/Explicit was performed using the incremental stress–strain curve, accompanied by Hill’s 1948 yield behavior. The incremental stress–strain curve was calculated using the β parameter, which was systematically assigned to adjust the trial stress at each strain increment of the FEM process. The correct incremental stress–strain curve was determined when the force prediction was in good agreement with the experiment.
Two-Step Resist Deposition of E-Beam Patterned Thick Py Nanostructures for X-ray Microscopy
Authors: Hermosa Javier , Hierro-Rodríguez Aurelio , Quirós Carlos , Vélez María , Sorrentino Andrea , Aballe Lucía , Pereiro Eva , Ferrer Salvador , Martín José I.
Published: January 2022

Patterned elements of permalloy (Py) with a thickness as large as 300 nm have been defined by electron beam lithography on X-ray-transparent 50 nm thick membranes in order to characterize their magnetic structure via Magnetic Transmission X-ray Microscopy (MTXM). To avoid the situation where the fragility of the membranes causes them to break during the lithography process, it has been found that the spin coating of the resist must be applied in two steps. The MTXM results show that our samples have a central domain wall, as well as other types of domain walls, if the nanostructures are wide enough.
Design and Optimization of a BAW Magnetic Sensor Based on Magnetoelectric Coupling
Authors: Ren Wanchun , Li Jintong , Liu Guo , Chen Jiarong , Chen Si , Gu Zhijun , Li Jianbo , Li Junru , Gao Yang
Published: January 2022

Magnetic sensors actuated by bulk acoustic wave (BAW) have attracted extensive attention due to the fact of their high sensitivity, GHz-level high frequency, and small size. Different from previous studies, suppression of energy loss and improvement in energy conversion efficiency of the BAW magnetoelectric (ME) sensor were systematically considered during the device design in this work. Finite element analysis models of material (magnetic composite), structure (ME heterostructure), and device (BAW ME magnetic sensor) were established and analyzed in COMSOL software. Additionally, the magnetic composite was prepared by radio frequency magnetron sputtering, and its soft magnetism was characterized by magnetic hysteresis loop and surface roughness. The research results demonstrate that after inserting four layers of 5 nm Al2O3 films, a performance of 86.7% eddy current loss suppression rate, a less than 1.1% magnetostriction degradation rate, and better soft magnetism were achieved in 600 nm FeGaB. Furthermore, compared with other structures, the two-layer piezomagnetic/piezoelectric heterostructure had a better ME coupling performance. Eventually, the design of the BAW ME magnetic sensor was optimized by the resonance-enhanced ME coupling to match the resonance frequency between the magnetic composite and the BAW resonator. When a 54,500 A/m direct current bias magnetic field was applied, the sensor worked at the first-order resonance frequency and showed good performance. Its linearity was better than 1.30%, the sensitivity was as high as 2.33 μmV/A, and the measurement range covered 0–5000 A/m.
Enhancement of Binding Kinetics on Affinity Substrates Using Asymmetric Electroosmotic Flow on a Sinusoidal Bipolar Electrode
Authors: Wu Yupan , Hu Bowen , Ma Xun , Wang Yucheng , Li Wei , Wang Shaoxi
Published: January 2022

In the context of the COVID-19 epidemic, enhancing the transport of analyte to a sensor surface is crucial for rapid detection of biomolecules since common conditions, including low diffusion coefficients, cause inordinately long detection times. Integrated microfluidic immunoassay chips are receiving increasing attention for their low sample volume and fast response time. We herein take advantage of asymmetric ICEO flow at a bipolar sinusoidal electrode to improve the rate of antibody binding to the reaction surface based on finite element modeling. Three different microfluidic cavities are proposed by changing the positions of the surface reaction area. We further investigate the relationship between binding enhancement and reaction surface positions, Damkohler number, and the voltage and frequency of the AC signal applied to the driving electrodes. Furthermore, the influence of the AC signal applied to the sinusoidal bipolar electrode on antigen–antibody-binding performance is studied in detail. Above all, the simulation results demonstrate that the microfluidic immune-sensor with a sinusoidal bipolar electrode could not only significantly improve the heterogeneous immunoassays but also enable efficient enhancement of assays in a selected reaction region within the micro-cavity, providing a promising approach to a variety of immunoassay applications, such as medical diagnostics and environmental and food monitoring.
The Grain Growth Control of ZnO-V2O5 Based Varistors by PrMnO3 Addition
Authors: Xu Maofeng , Cai Changkun , Shi Yu , Xie Manyi , Wu Yanlong , Liu Yuanyuan , Peng Jun , Bao Jinxiao , An Shengli
Published: January 2022

In this study, the grain growth behaviour of ZnO-V2O5-based ceramics with 0.25–0.75 mol% additions of PrMnO3 was systematically investigated during sintering from 850 °C to 925 °C. with the aim to control the ZnO grain size for their application as varistors. It was found that with the increased addition of PrMnO3, in addition to the decrease in the average grain size, the grain size distribution also narrowed and eventually changed from a bimodal to unimodal distribution after a 0.75 mol% PrMnO3 addition. The grain growth control was achieved by a pinning effect of the secondary ZnCr2O4 and PrVO4 phases at the ZnO grain boundaries. The apparent activation energy of the ZnO grain growth in these ceramics was found to increase with increased additions of PrVO4, hence the observed reduction in the ZnO grain sizes.
A Combination of Aqueous Extraction and Ultrafiltration for the Purification of Phycocyanin from Arthrospira maxima
Authors: Nisticò Dante Matteo , Piro Amalia , Oliva Daniela , Osso Vincenzo , Mazzuca Silvia , Fagà Francesco Antonio , Morelli Rosanna , Conidi Carmela , Figoli Alberto , Cassano Alfredo
Published: January 2022

The purification of phycocyanin (PC) from Spirulina generally involves a combination of different techniques. Here, we report the results on PC yields from a combined aqueous extraction-ultrafiltration (UF) process of a strain of Arthrospira maxima cultivated in a farm devoted to producing PC with food-grade purity. Samples optimized from different biomass/solvent ratios were purified by using a polyethersulphone (PES) membrane with a molecular weight cut-off (MWCO) of 20 kDa. The UF system was operated at 2.0 ± 0.1 bar and at 24 ± 2 °C up to a volume concentration factor (VCF) of 5. A diafiltration (DF) process was conducted after UF in order to increase the PC recovery in the retentate. Samples were collected during both UF and DF processes in order to evaluate membrane productivity and PC purity. The average permeate fluxes of about 14.4 L/m2h were measured in the selected operating conditions and more than 96% of PC was rejected by the UF membrane independently ofthe extraction yields and times. The concentration of PC in the final retentate was 1.17 mg/mL; this confirmed the observed rejection and the final VCF of the process (about 5-fold when compared to the concentration of PC in the crude extract). In addition, the combination of UF and diafiltration allowed the removal of about 91.7% of the DNA from the crude extract, thereby improving the purity of the phycocyanin in the retentate fraction.
Special Issue: Microbiota–Gut–Brain Axis
Authors: Obrenovich Mark , Reddy V. Prakash
Published: January 2022

There is emerging evidence that human health and disease are modulated by the microbiota and their various metabolites, formed through intestinal and gut bacterial metabolism [...]
Infection of Human Retinal Pigment Epithelial Cells with Dengue Virus Strains Isolated during Outbreaks in Singapore
Authors: Ashander Liam M. , Lumsden Amanda L. , Dawson Abby C. , Ma Yuefang , Ferreira Lisia B. , Oliver Genevieve F. , Appukuttan Binoy , Carr Jillian M. , Smith Justine R.
Published: January 2022

Prevalence of dengue retinopathy varies across epidemics, with the disease linked to circulation of dengue virus serotype 1 (DENV-1). The retinal pigment epithelium has been implicated in the pathology. We investigated infectivity, molecular response, and barrier function of epithelial cells inoculated with DENV strains from different outbreaks in Singapore. Monolayers of human retinal pigment epithelial cells (multiple primary cell isolates and the ARPE-19 cell line) were inoculated with six DENV strains, at multiplicity of infection of 10; uninfected and recombinant strain-infected controls were included where relevant. Infectivity and cell response were assessed primarily by RT-qPCR on total cellular RNA, and barrier function was evaluated as electrical resistance across monolayers. Higher viral RNA loads were measured in human retinal pigment epithelial cells infected with DENV-1 strains from the 2005 Singapore epidemic, when retinopathy was prevalent, versus DENV-1 strains from the 2007 Singapore epidemic, when retinopathy was not observed. Type I interferon (IFN) transcripts (IFN-β and multiple IFN-stimulated genes) were up-regulated, and impact on barrier function was more pronounced, for cells infected with DENV-1 strains from the 2005 versus the 2007 Singapore epidemics. Aside from serotype, strain of DENV may determine the potential to induce retinal pathology. Identification of molecular markers of disease-associated DENV strains may provide insights into the pathogenesis of dengue retinopathy.
Characterization of Microorganisms from Protaetia brevitarsis Larva Frass
Authors: Xuan Huina , Gao Peiwen , Du Baohai , Geng Lili , Wang Kui , Huang Kun , Zhang Jie , Huang Tianpei , Shu Changlong
Published: January 2022

Decomposers play an important role in the biogeochemical cycle. Protaetia brevitarsis larvae (PBLs) can transform wastes into frass rich in humic acid (HA) and microorganisms, which may increase the disease resistance of plants and promote plant growth. Beyond HA, the microorganisms may also contribute to the biostimulant activity. To address this hypothesis, we investigated the potential microbial community in the PBL frass samples and elucidated their functions of disease resistance and plant growth promotion. High-throughput sequencing analysis of four PBL-relevant samples showed that their frass can influence the microbial community of the surrounding environment. Further analysis showed that there were many microorganisms beneficial to agriculture, such as Bacillus. Therefore, culturable Bacillus microbes were isolated from frass, and 16S rDNA gene analysis showed that Bacillus subtilis was the dominant species. In addition, some Bacillus microorganisms isolated from the PBL frass had antibacterial activities against pathogenic fungi. The plant growth promotion pot experiment also proved that some strains promote plant growth. In conclusion, this study demonstrated that the microorganisms in the PBL frass are conducive to colonizing the surrounding organic matrix, which will help beneficial microbes to increase the disease resistance of plants and promote plant growth.
Pseudomonas protegens FJKB0103 Isolated from Rhizosphere Exhibits Anti-Methicillin-Resistant Staphylococcus aureus Activity
Authors: Zhao Hui , Liu Lu , Yang Lingshuang , Gu Qihui , Li Ying , Zhang Jumei , Wu Shi , Chen Moutong , Xie Xinqiang , Wu Qingping
Published: January 2022

Staphylococcus aureus is amongst the most virulent pathogens, causing chronic and life-threatening human infections. Methicillin-resistant S. aureus (MRSA) are multidrug-resistant strains, and the ability of forming a biofilm reduces their sensitivity to antibiotics. Thus, the alternative compounds inhibiting both resistant strains and biofilm formation are in high demand. In our study, the strain FJKB0103 was isolated from the rhizosphere of Garcinia mangostana, showing strong anti-MRSA activity. We performed molecular phylogenic analysis, analyzed average nucleotide identity (ANI), in silico DNA-DNA hybridization (isDDH), and biochemical characteristics to identify strain FJKB0103 as Pseudomonas protegens. Herein, the genome of strain FJKB0103 was sequenced and subjected to antiSMASH platform, mutational, and functional analyses. The FJKB0103 draft genome was 6,776,967 bp with a 63.4% G + C content, and 16 potential secondary compound biosynthetic clusters in P. protegens FJKB0103 were predicted. The deletion mutant and complementary analysis suggested that DAPG was the anti-MRSA compound. Further tests showed that MRSA strains were sensitive to DAPG, and the lysis of bacterial cells was observed at a high concentration of DAPG. Additionally, DAPG inhibited the biofilm formation of MRSA at subinhibitory concentration. These results suggested that DAPG might be a good alternative treatment to control infections caused by MRSA.
Efficient Recovery of Vanadium from High-Chromium Vanadium Slag with Calcium-Roasting Acidic Leaching
Authors: Peng Hao , Li Bing , Shi Wenbing , Liu Zuohua
Published: January 2022

High-chromium vanadium slag (HCVS) is an important by-product generated during the smelting process of high-chromium-vanadium-titanium-magnetite. Direct acid leaching and calcium-roasting acid leaching technology were applied to recover vanadium and chromium from HCVS. The effects of experimental parameters on the leaching process, including concentration of H2SO4, reaction temperature, reaction time, and liquid-to-solid ratio, were investigated. The XRD and UV-Vis DRS results showed that vanadium and chromium existed in low valence with a spinel structure in the HCVS. The Cr-spinel was too stable to leach out; no more than 8% of the chromium could be leached out both in the direct acid leaching process and calcium-roasting acid-leaching process. Most low valence vanadium could be oxidized to high valence with calcium-roasting technology, and the leaching efficiency could be increased from 33.89% to 89.12% at the selected reaction conditions: concentration of H2SO4 at 40 vt.%, reaction temperature of 90 °C, reaction time of 3 h, liquid-to-solid ratio of 4:1 mL/g, and stirring rate of 500 rpm. The kinetics analysis indicated that the leaching behavior of vanadium followed the shrinking core model well, and the leaching process was controlled by the surface chemical reaction, with an Ea of 58.95 kJ/mol and 62.98 kJ/mol for direct acid leaching and roasting acid leaching, respectively.
Light Intensity and Photoperiod Affect Growth and Nutritional Quality of Brassica Microgreens
Authors: Liu Kaizhe , Gao Meifang , Jiang Haozhao , Ou Shuying , Li Xiaopeng , He Rui , Li Yamin , Liu Houcheng
Published: January 2022

We explored the effects of different light intensities and photoperiods on the growth, nutritional quality and antioxidant properties of two Brassicaceae microgreens (cabbage Brassica oleracea L. and Chinese kale Brassica alboglabra Bailey). There were two experiments: (1) four photosynthetic photon flux densities (PPFD) of 30, 50, 70 or 90 μmoL·m−2·s−1 with red:blue:green = 1:1:1 light-emitting diodes (LEDs); (2) five photoperiods of 12, 14, 16, 18 or 20 h·d−1. With the increase of light intensity, the hypocotyl length of cabbage and Chinese kale microgreens shortened. PPFD of 90 μmol·m−2·s−1 was beneficial to improve the nutritional quality of cabbage microgreens, which had higher contents of chlorophyll, carotenoids, soluble sugar, soluble protein and vitamin C, as well as increased antioxidant capacity. The optimal PPFD for Chinese kale microgreens was 70 μmol·m−2·s−1. Increasing light intensity could increase the antioxidant capacity of cabbage and Chinese kale microgreens, while not significantly affecting glucosinolate (GS) content. The dry and fresh weight of cabbage and Chinese kale microgreens were maximized with a 14-h·d−1 photoperiod. The chlorophyll, carotenoid and soluble protein content in cabbage and Chinese kale microgreens were highest for a 16-h·d−1 photoperiod. The lowest total GS content was found in cabbage microgreens under a 12-h·d−1 photoperiod and in Chinese kale microgreens under 16-h·d−1 photoperiod. In conclusion, the photoperiod of 14~16 h·d−1, and 90 μmol·m−2·s−1 and 70 μmol·m−2·s−1 PPFD for cabbage and Chinese kale microgreens, respectively, were optimal for cultivation.
Recent Advances in the Chemistry and Therapeutic Evaluation of Naturally Occurring and Synthetic Withanolides
Authors: Singh Amandeep , Raza Asif , Amin Shantu , Damodaran Chendil , Sharma Arun K.
Published: January 2022

Natural products are a major source of biologically active compounds that make promising lead molecules for developing efficacious drug-like molecules. Natural withanolides are found in many flora and fauna, including plants, algae, and corals, that traditionally have shown multiple health benefits and are known for their anti-cancer, anti-inflammatory, anti-bacterial, anti-leishmaniasis, and many other medicinal properties. Structures of these withanolides possess a few reactive sites that can be exploited to design and synthesize more potent and safe analogs. In this review, we discuss the literature evidence related to the medicinal implications, particularly anticancer properties of natural withanolides and their synthetic analogs, and provide perspectives on the translational potential of these promising compounds.
Antileishmanial Effects of Acetylene Acetogenins from Seeds of Porcelia macrocarpa (Warm.) R.E. Fries (Annonaceae) and Semisynthetic Derivatives
Authors: Brito Ivanildo A. , Thevenard Fernanda , Costa-Silva Thais A. , Oliveira Samuel S. , Cunha Rodrigo L. O. R. , de Oliveira Emerson A. , Sartorelli Patricia , Guadagnin Rafael C. , Romanelli Maiara M. , Tempone Andre G. , Lago João Henrique G.
Published: January 2022

As part of our continuous studies involving the prospection of natural products from Brazilian flora aiming at the discovery of prototypes for the development of new antiparasitic drugs, the present study describes the isolation of two natural acetylene acetogenins, (2S,3R,4R)-3-hydroxy-4-methyl-2-(n-eicos-11′-yn-19′-enyl)butanolide (1) and (2S,3R,4R)-3-hydroxy-4-methyl-2-(n-eicos-11′-ynyl)butanolide (2), from the seeds of Porcelia macrocarpa (Warm.) R.E. Fries (Annonaceae). Using an ex-vivo assay, compound 1 showed an IC50 value of 29.9 μM against the intracellular amastigote forms of Leishmania (L.) infantum, whereas compound 2 was inactive. These results suggested that the terminal double bond plays an important role in the activity. This effect was also observed for the semisynthetic acetylated (1a and 2a) and eliminated (1b and 2b) derivatives, since only compounds containing a double bond at C-19 displayed activity, resulting in IC50 values of 43.3 μM (1a) and 23.1 μM (1b). In order to evaluate the effect of the triple bond in the antileishmanial potential, the mixture of compounds 1 + 2 was subjected to catalytic hydrogenation to afford a compound 3 containing a saturated side chain. The antiparasitic assays performed with compound 3, acetylated (3a), and eliminated (3b) derivatives confirmed the lack of activity. Furthermore, an in-silico study using the SwissADME online platform was performed to bioactive compounds 1, 1a, and 1b in order to investigate their physicochemical parameters, pharmacokinetics, and drug-likeness. Despite the reduced effect against amastigote forms of the parasite to the purified compounds, different mixtures of compounds 1 + 2, 1a + 2a, and 1b + 2b were prepared and exhibited IC50 values ranging from 7.9 to 38.4 μM, with no toxicity for NCTC mammalian cells (CC50 > 200 μM). Selectivity indexes to these mixtures ranged from >5.2 to >25.3. The obtained results indicate that seeds of Porcelia macrocarpa are a promising source of interesting prototypes for further modifications aiming at the discovery of new antileishmanial drugs.
Dittrichia graveolens (L.) Greuter, a Rapidly Spreading Invasive Plant: Chemistry and Bioactivity
Authors: Ponticelli Maria , Lela Ludovica , Russo Daniela , Faraone Immacolata , Sinisgalli Chiara , Mustapha Mayssa Ben , Esposito Germana , Jannet Hichem Ben , Costantino Valeria , Milella Luigi
Published: January 2022

Dittrichia graveolens L. Greuter belonging to the Asteraceae family, is an aromatic herbaceous plant native to the Mediterranean region. This plant species has been extensively studied for its biological activities, including antioxidant, antitumor, antimicrobial, antifungal, anti-inflammatory, anticholinesterase, and antityrosinase, and for its peculiar metabolic profile. In particular, bioactivities are related to terpenes and flavonoids metabolites, such as borneol (40), tomentosin (189), inuviscolide (204). However, D. graveolens is also well known for causing health problems both in animals and humans. Moreover, the species is currently undergoing a dramatic northward expansion of its native range related to climate change, now including North Europe, California, and Australia. This review represents an updated overview of the 52 literature papers published in Scopus and PubMed dealing with expansion, chemistry (262 different compounds), pharmacological effects, and toxicology of D. graveolens up to October 2021. The review is intended to boost further studies to determine the molecular pathways involved in the observed activities, bioavailability, and clinical studies to explore new potential applications.
Design of Turmeric Rhizome Extract Nano-Formula for Delivery to Cancer Cells
Authors: Auychaipornlert Sakchai , Lawanprasert Pojawon Prayurnprohm , Piriyaprasarth Suchada , Sithisarn Pongtip , Mangmool Supachoke
Published: January 2022

Novel turmeric rhizome extract nanoparticles (TE-NPs) were developed from fractions of dried turmeric (Curcuma longa Linn.) rhizome. Phytochemical studies, by using HPLC and TLC, of the fractions obtained from ethanol extraction and solvent–solvent extraction showed that turmeric rhizome ethanol extract (EV) and chloroform fraction (CF) were composed mainly of three curcuminoids and turmeric oil. Hexane fraction (HE) was composed mainly of turmeric oil while ethyl acetate fraction (EA) was composed mainly of three curcuminoids. The optimal TE-NPs formulation with particle size of 159.6 ± 1.7 nm and curcumin content of 357.48 ± 8.39 µM was successfully developed from 47-run D-optimal mixture–process variables experimental design. Three regression models of z-average, d50, and d90 could be developed with a reasonable accuracy of prediction (predicted r2 values were in the range of 0.9120–0.9992). An in vitro cytotoxicity study using MTT assay demonstrated that the optimal TE-NPs remarkably exhibited the higher cytotoxic effect on human hepatoma cells, HepG2, when compared with free curcumin. This study is the first to report nanoparticles prepared from turmeric rhizome extract and their cytotoxic activity to hepatic cancer cells compared with pure curcumin. These nanoparticles might serve as a potential delivery system for cancer therapy.