bluuebunny/crossref_metadata_2025 huggingface dataset:
Influence of Climate Change on the Thermal Condition of Yakutia’s Permafrost Landscapes (Chabyda Station)
Authors: Varlamov Stepan P , Skachkov Yuri B , Skryabin Pavel N
Published: April 2020

This paper presents the results of 39 years of observations conducted at the Chabyda station to monitor the thermal state of permafrost landscapes under current climatic warming. The analysis of long-term records from weather stations in the region has revealed one of the highest increasing trends in mean annual air temperature in northern Russia. The partitioning of the energy balance in different landscape units within the study area has been analyzed. Quantitative relationships in the long-term variability of ground thermal parameters, such as the ground temperature at the bottom of the active layer and seasonal thaw depth, have been established. The ground temperature dynamics within the depth of zero annual amplitude indicates that both warm and cold permafrost are thermally stable. The short-term variability of the snow accumulation regime is the main factor controlling the thermal state of the ground in permafrost landscapes. The depth of seasonal thaw is characterized by low interannual variability and exhibits little response to climate warming, with no statistically significant increasing or decreasing trend. The results of the ground thermal monitoring can be extended to similar landscapes in the region, providing a reliable basis for predicting heat transfer in natural, undisturbed landscapes.
Land Functions, Rural Space Governance, and Farmers’ Environmental Perceptions: A Case Study from the Huanjiang Karst Mountain Area, China
Authors: Wan Jiangjun , Su Yi , Zan Huanglin , Zhao Yutong , Zhang Lingqing , Zhang Shaoyao , Dong Xiangyu , Deng Wei
Published: April 2020

Residents of rural areas live and depend on the land; hence, rural land plays a central role in the human–land relationship. The environment has the greatest direct impact on farmers’ lives and productivity. In recent years, the Chinese government carried out vigorous rural construction under a socialist framework and implemented a rural revitalization strategy. This study was performed in a rural area of Huanjiang County, Guangxi Province, China. We designed a survey to measure rural households’ perceptions of three types of rural spaces: ecological, living, and production spaces. The survey was administered to 379 farmers, and their perceptions and satisfaction with Ecological–Living–Productive spaces were evaluated with the use of structural equation modeling. Analysis of latent and observed variables indicates that: (1) Farmers’ overall satisfaction with Ecological–Living–Productive spaces was moderate. The average satisfaction score for production spaces was lowest (2.881) while that for living spaces was highest (3.468) and that for ecological spaces was in between (3.351). (2) The three most important exogenous observed variables associated with living space satisfaction were house comfort > domestic water supply > domestic sewage treatment. The three most important exogenous observed variables associated with production space satisfaction were irrigation water > cultivated land quantity > cultivated land fertility. The three most important exogenous observed variables associated with ecological space satisfaction were garbage disposal > vegetation cover > flood and waterlogging. Based on the requirements of the rural revitalization strategy and the results of our analyses of rural households’ spatial perceptions, we propose corresponding countermeasures and suggestions.
Development of Thermal Resistant FDM Printed Blends. The Preparation of GPET/PC Blends and Evaluation of Material Performance
Authors: Andrzejewski Jacek , Marciniak-Podsadna Lidia
Published: April 2020

The paper discusses the preparation of polymer blends based on the polyethylene terephthalate copolymer/polycarbonate (GPET/PC). Materials have been prepared in order to assess their applicability in the fused deposition modeling (FDM) 3D printing process. The tested key feature was the thermomechanical resistance, measured by head deflection temperature (HDT) and Vicat softening temperature (VST), the mechanical tests and dynamic mechanical thermal analysis (DMTA) were also performed. A clear relationship between the increasing content of PC in the blend properties was observed. DMTA analysis revealed significant changes in the glass transition temperature, which indicates the miscibility of this type of polymer system. The mechanical tests indicate a clear trend of stiffness and strength improvement along with the increasing share of PC phase in the structure. The increase in impact strength is also clear, however, compared to the results for a pure PC, the results obtained for GPET/PC blends are significantly lower. As part of the research, reference samples based on polyethylene terephthalate homopolymer (PET) and composite samples with addition of 10% talc were also prepared. The structure analysis for PET/PC(50/50) samples did not show miscibility. However, due to the formation of the PET crystalline phase, the thermomechanical resistance of these materials was visibly higher. Scanning electron microscopy (SEM) analysis confirmed a high degree of compatibility of the GPET/PC blend structure as indicated by the lack of visible signs of phase separation. This phenomenon is not observed for PET/PC blends, which confirms the different thermomechanical interactions of both tested polymer systems.
Lanthanum Ferrite Ceramic Powders: Synthesis, Characterization and Electrochemical Detection Application
Authors: Dumitru Raluca , Negrea Sorina , Ianculescu Adelina , Păcurariu Cornelia , Vasile Bogdan , Surdu Adrian , Manea Florica
Published: April 2020

The perovskite-type lanthanum ferrite, LaFeO3, has been prepared by thermal decomposition of in situ obtained lanthanum ferrioxalate compound precursor, LaFe(C2O4)3·3H2O. The oxalate precursor was synthesized through the redox reaction between 1,2-ethanediol and nitrate ion and characterized by chemical analysis, infrared spectroscopy, and thermal analysis. LaFeO3 obtained after the calcination of the precursor for at least 550–800 °C/1 h have been investigated by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), and high-resolution transmission electron microscopy (HRTEM). A boron-doped diamond electrode (BDD) modified with LaFeO3 ceramic powders at 550 °C (LaFeO3/BDD) by simple immersion was characterized by cyclic voltammetry and tested for the voltammetric and amperometric detection of capecitabine (CCB), which is a cytostatic drug considered as an emerging pollutant in water. The modified electrode exhibited a complex electrochemical behaviour by several redox systems in direct relation to the electrode potential range. The results obtained by cyclic voltammetry (CV), differential-pulsed voltammetry (DPV), and multiple-pulsed amperometry proved the electrocatalytic effect to capecitabine oxidation and reduction and allowed its electrochemical detection in alkaline aqueous solution.
Influence of Zinc Content on the Mechanical Behaviors of Cu-Zn Alloys by Molecular Dynamics
Authors: Jang Heung Woon , Hong Jung-Wuk
Published: April 2020

The mechanical properties of copper alloys containing various ratios of zinc are evaluated using molecular dynamics (MD) simulations to determine the impact of the different zinc concentrations. The modified embedded atom method (MEAM) parameters for copper were established in the 1990s; however, the MEAM potential parameters for zinc, with an axial ratio >1, were recently proposed. In this research, the MD models of the copper alloys with various zinc contents are constructed using the MEAM potential parameters for zinc. Tensile test simulations are also conducted. The strain rate effects of the alloys are evaluated at four different strain rates, and the variations in the tensile strengths and Young’s modulus are investigated. The proposed procedures have significant potential applicability for simulating a variety of zinc-containing alloys.
Emerging Research in Chronic Pruritus: From Bedside to Bench and Back Again
Authors: Williams Kyle A. , Kwatra Shawn G.
Published: April 2020

This Medicines special issue highlights emerging research spanning from epidemiology to diagnostic workup, pathogenesis, and therapeutics for patients suffering from chronic pruritus. The special issue contains 13 articles reporting relevant epidemiologic and experimental data on chronic pruritus.
Industrial Wastewater Treatment by Nanofiltration—A Case Study on the Anodizing Industry
Authors: Ali Aamer , Nymann Maria C. , Christensen Morten L. , Quist-Jensen Cejna A.
Published: April 2020

The anodizing industry generates several alkaline and acidic wastewater streams often with high concentrations of heavy metals. In this study, nanofiltration (NF) was used to treat wastewater from individual baths, i.e., wastewater from color rinse, alkaline pickling rinse, acidic pickling rinse and anodizing rinse, as well as a mixture of all the wastewater streams. The experiments were carried out by using a commercial membrane (NF99HF) exhibiting pure water permeability of 10 L/(m2·h·bar). For all wastewater streams except one, pH was adjusted to bring it within the recommended pH limits of the membrane, whereby part of the heavy metals precipitated and was removed. The NF of the color rinse offered high-quality permeate (heavy metals below detection limit) and high permeability (9 L/(m2·h·bar)), whereas the nanofiltration of the alkaline pickling rinse exhibited no permeability. The NF of the acidic pickling rinse showed a permeability of 3.1–4.1 L/(m2·h·bar), but low ion rejection (7–13%). NF of the neutralized mixed wastewater, after the removal of precipitate, produced high-quality permeate with a stable permeability of 1 L/(m2·h·bar). Treatment of the mixed wastewater is therefore the best option if the water has to be discharged. If the water has to be reused, the permeate conductivity in the color rinse and anodizing rinse baths have been reduced significantly, so the treatment of these streams may then be a better option.
Characterization of an Extruded Mg-Dy-Nd Alloy during Stress Corrosion with C-Ring Tests
Authors: Maier Petra , Clausius Benjamin , Wicke Jens , Hort Norbert
Published: April 2020

This study focuses on the characterization of the failure behavior of an extruded Mg10Dy1Nd alloy during stress corrosion. The microstructure, hardness, strength and corrosion behavior of binary alloys Mg10Dy and Mg1Nd are compared to those of the ternary alloy system. The ternary alloy Mg-Dy-Nd that is not fully recrystallized has the highest hardness but lacks ductility. The investigated alloys twin during plastic deformation. Static C-ring tests in Ringer solution were used to evaluate the stress corrosion properties, and stress corrosion could not be found. None of the alloys failed by fracturing, but corrosion pits formed to various extents. These corrosion pits were elliptical in shape and located below the surface. Some of the pits reduced the remaining wall thickness significantly, but the stress increased by the notch effect did not lead to crack initiation. Furthermore, the C-ring specimen was subjected to compressive loading until fracture. Whereas the Mg1Nd alloy showed ductile behavior, the alloys containing Dy fractured on the tensile side. The crack initiation and growth were mainly influenced by the twin boundaries. The Mg10Dy1Nd alloy had an inhomogeneous microstructure and low ductility, which resulted in a lower fracture toughness than that of the Mg10Dy alloy. There were features that indicate hydrogen-assisted fracture. Although adding Nd decreased the fracture toughness, it reduced the grain size and had a positive influence on the corrosion rate during immersion testing.
Metabolic Engineering Design Strategies for Increasing Acetyl-CoA Flux
Authors: Ku Jason T. , Chen Arvin Y. , Lan Ethan I.
Published: April 2020

Acetyl-CoA is a key metabolite precursor for the biosynthesis of lipids, polyketides, isoprenoids, amino acids, and numerous other bioproducts which are used in various industries. Metabolic engineering efforts aim to increase carbon flux towards acetyl-CoA in order to achieve higher productivities of its downstream products. In this review, we summarize the strategies that have been implemented for increasing acetyl-CoA flux and concentration, and discuss their effects. Furthermore, recent works have developed synthetic acetyl-CoA biosynthesis routes that achieve higher stoichiometric yield of acetyl-CoA from glycolytic substrates.
Mechanism of Chronic Kidney Disease Progression and Novel Biomarkers: A Metabolomic Analysis of Experimental Glomerulonephritis
Authors: Han Kyoung Hee , Kim Bora , Ji Sang Chun , Kang Hee Gyung , Cheong Hae Il , Cho Joo-Youn , Ha Il-Soo
Published: April 2020

While a complex network of cellular and molecular events is known to be involved in the pathophysiological mechanism of chronic kidney disease (CKD), the divergence point between reversal and progression and the event that triggers CKD progression are still unknown. To understand the different mechanisms between reversible and irreversible kidney disease and to search for urinary biomarkers that can predict prognosis, a metabolomic analysis was applied to compare acute and chronic experimental glomerulonephritis (GN) models. Four metabolites, namely, epoxyoctadecenoic acid (EpOME), epoxyeicosatetraenoic acid (EpETE), α-linolenic acid (ALA), and hydroxyretinoic acid, were identified as predictive markers after comparing the chronic nephritis model with acute nephritis and control groups (false discovery rate adjusted p-value (q-value) < 0.05). Renal mRNA expression of cytochrome P450 and epoxide hydrolase was also identified as being involved in the production of epoxide metabolites from these polyunsaturated fatty acids (p < 0.05). These results suggested that the progression of chronic kidney disease is associated with abnormally activated epoxide hydrolase, leading to an increase in EpOME and EpETE as pro-inflammatory eicosanoids.
Volatilomics Reveals Potential Biomarkers for Identification of Renal Cell Carcinoma: An In Vitro Approach
Authors: Amaro Filipa , Pinto Joana , Rocha Sílvia , Araújo Ana Margarida , Miranda-Gonçalves Vera , Jerónimo Carmen , Henrique Rui , Bastos Maria de Lourdes , Carvalho Márcia , Guedes de Pinho Paula
Published: April 2020

The identification of noninvasive biomarkers able to detect renal cell carcinoma (RCC) at an early stage remains an unmet clinical need. The recognition that altered metabolism is a core hallmark of cancer boosted metabolomic studies focused in the search for cancer biomarkers. The present work aims to evaluate the performance of the volatile metabolites present in the extracellular medium to discriminate RCC cell lines with distinct histological subtypes (clear cell and papillary) and metastatic potential from non-tumorigenic renal cells. Hence, volatile organic compounds (VOCs) and volatile carbonyl compounds (VCCs) were extracted by headspace solid-phase microextraction (HS-SPME) and analyzed by gas chromatography–mass spectrometry (GC–MS). Multivariate and univariate analysis unveiled a panel of metabolites responsible for the separation between groups, mostly belonging to ketones, alcohols, alkanes and aldehydes classes. Some metabolites were found similarly altered for all RCC cell lines compared to non-tumorigenic cells, namely 2-ethylhexanol, tetradecane, formaldehyde, acetone (increased) and cyclohexanone and acetaldehyde (decreased). Furthermore, significantly altered levels of cyclohexanol, decanal, decane, dodecane and 4-methylbenzaldehyde were observed in all metastatic RCC cell lines when compared with the non-metastatic ones. Moreover, some alterations in the volatile composition were also observed between RCC histological subtypes. Overall, our results demonstrate the potential of volatile profiling for identification of noninvasive candidate biomarkers for early RCC diagnosis.
Biochemical Characteristics and a Genome-Scale Metabolic Model of an Indian Euryhaline Cyanobacterium with High Polyglucan Content
Authors: Ahmad Ahmad , Pathania Ruchi , Srivastava Shireesh
Published: April 2020

Marine cyanobacteria are promising microbes to capture and convert atmospheric CO2 and light into biomass and valuable industrial bio-products. Yet, reports on metabolic characteristics of non-model cyanobacteria are scarce. In this report, we show that an Indian euryhaline Synechococcus sp. BDU 130192 has biomass accumulation comparable to a model marine cyanobacterium and contains approximately double the amount of total carbohydrates, but significantly lower protein levels compared to Synechococcus sp. PCC 7002 cells. Based on its annotated chromosomal genome sequence, we present a genome scale metabolic model (GSMM) of this cyanobacterium, which we have named as iSyn706. The model includes 706 genes, 908 reactions, and 900 metabolites. The difference in the flux balance analysis (FBA) predicted flux distributions between Synechococcus sp. PCC 7002 and Synechococcus sp. BDU130192 strains mimicked the differences in their biomass compositions. Model-predicted oxygen evolution rate for Synechococcus sp. BDU130192 was found to be close to the experimentally-measured value. The model was analyzed to determine the potential of the strain for the production of various industrially-useful products without affecting growth significantly. This model will be helpful to researchers interested in understanding the metabolism as well as to design metabolic engineering strategies for the production of industrially-relevant compounds.
Continuous Detection of Increasing Concentrations of Thrombin Employing a Label-Free Photonic Crystal Aptasensor
Authors: Martínez-Pérez Paula , Gómez-Gómez Maribel , Angelova Todora , Griol Amadeu , Hurtado Juan , Bellieres Laurent , García-Rupérez Jaime
Published: April 2020

Thrombin generation is a complex and finely regulated pathway that provokes dynamical changes of thrombin concentration in blood when a vascular injury occurs. In order to characterize the initiation phase of such process, when thrombin concentration is in the nM range, a label-free optical aptasensor is proposed here. This aptasensor combines a 1D photonic crystal structure consisting of a silicon corrugated waveguide with thrombin binding aptamers on its surface as bioreceptors. As a result, this aptasensor has been demonstrated to specifically detect thrombin concentrations ranging from 270 pM to 27 nM with an estimated detection limit of 33.5 pM and a response time of ~2 min. Furthermore, it has also been demonstrated that this aptasensor is able to continuously respond to consecutive increasing concentrations of thrombin and to detect binding events as they occur. All these features make this aptasensor a good candidate to continuously study how thrombin concentration progressively increases during the initiation phase of the coagulation cascade.
A Reliable Flow-Based Method for the Accurate Measure of Mass Density, Size and Weight of Live 3D Tumor Spheroids
Authors: Cristaldi Domenico Andrea , Sargenti Azzurra , Bonetti Simone , Musmeci Francesco , Delprete Cecilia , Bacchi Francesco , Pasqua Simone , Cavallo Carola , Bonsi Laura , Alviano Francesco , Gazzola Daniele , Santi Spartaco
Published: April 2020

Gathering precise information on mass density, size and weight of cells or cell aggregates, is crucial for applications in many biomedical fields with a specific focus on cancer research. Although few technical solutions have been presented for single-cell analysis, literature does not cover this aspect for 3D models such as spheroids. Since the research interest on such samples is notably rising, here we describe a flow-apparatus, and the associated physical method and operative protocol for the accurate measurements of mass density, size and weight. The technique is based on the detection of the terminal velocity of a free-falling sample into a specifically conceived analysis flow-channel. Moreover, in order to demonstrate the accuracy and precision of the presented flow-device, analyses were initially carried out on standardized polystyrene beads. Finally, to display the application of the proposed system for biological samples, mass density, size and weight of live SW620 tumor spheroids were analyzed. The combined measurements of such parameters can represent a step toward a deeper understanding of 3D culture models.
Fabrication of Subretinal 3D Microelectrodes with Hexagonal Arrangement
Authors: Seo Hee Won , Kim Namju , Kim Sohee
Published: April 2020

This study presents the fabrication of three-dimensional (3D) microelectrodes for subretinal stimulation, to accommodate adjacent return electrodes surrounding a stimulating electrode. For retinal prosthetic devices, the arrangement of return electrodes, the electrode size and spacing should be considered together, to reduce the undesired dissipation of electric currents. Here, we applied the hexagonal arrangement to the microelectrode array for the localized activation of retinal cells and better visual acuity. To provide stimuli more efficiently to non-spiking neurons, a 3D structure was created through a customized pressing process, utilizing the elastic property of the materials used in the fabrication processes. The diameter and pitch of the Pt-coated electrodes were 150 μm and 350 μm, respectively, and the height of the protruded electrodes was around 20 μm. The array consisted of 98 hexagonally arranged electrodes, supported by a flexible and transparent polydimethylsiloxane (PDMS) base, with a thickness of 140 μm. Also, the array was coated with 2 μm-thick parylene-C, except the active electrode sites, for more focused stimulation. Finally, the electrochemical properties of the fabricated microelectrodes were characterized, resulting in the mean impedance of 384.87 kΩ at 1 kHz and the charge storage capacity (CSC) of 2.83 mC·cm−2. The fabricated microelectrodes are to be combined with an integrated circuit (IC) for additional in vitro and in vivo experiments.
Milling Microchannels in Monel 400 Alloy by Wire EDM: An Experimental Analysis
Authors: Saleh Mustafa , Anwar Saqib , El-Tamimi Abdualziz , Khan Mohammed Muneer , Ahmad Shafiq
Published: April 2020

This paper presents the results of an investigation on the capacity of wire electrical discharge machining (WEDM) to produce microchannels in the Nickel-based alloy, Monel 400. The main objective of the current study is to produce microchannels with desired/target geometry and acceptable surface quality. Square cross-sectional microchannels with dimensions of 500 × 500 µm were investigated. Experiments were conducted based on the one-factor-at-a-time approach for the key input WEDM process parameters, namely pulse-on time (TON), pulse-off time (TOFF), average gap voltage (VGAP), wire feed (WF), and dielectric flow rate (FR). Dimensional accuracy, machining speed, surface roughness, surface morphology, microhardness, and microstructure were analyzed to evaluate the microchannels. The minimum errors of 6% and 3% were observed in the width and depth of the microchannels, respectively. Furthermore, microchannels with enhanced surface integrity could be produced exhibiting smooth surface morphology and shallow recast layer (~0–2.55 µm).
Temporal Dynamics of Bacterial Communities in a Pilot-Scale Vermireactor Fed with Distilled Grape Marc
Authors: Gómez-Brandón María , Aira Manuel , Santana Natielo , Pérez-Losada Marcos , Domínguez Jorge
Published: April 2020

Vermicomposting has been found as a profitable approach to dispose of and treat large quantities of raw grape marc. However, less information is available with regard to its efficiency for treating distillery winery byproducts, even though distillation has been widely used as a way to economically valorize grape marc. As such, we sought to characterize the compositional and functional changes in bacterial communities during vermicomposting of distilled grape marc by using 16S rRNA high-throughput sequencing. Samples were collected at the initiation of vermicomposting and at days 14, 21, 28, 35 and 42. There were significant changes (p < 0.0001) in the bacterial community composition of distilled grape marc after 14 days of vermicomposting that were accompanied by twofold increases in bacterial richness and diversity from a taxonomic and phylogenetic perspective. This was followed by significant increases in functional diversity of the bacterial community, including metabolic capacity, lignin and cellulose metabolism, and salicylic acid synthesis. These findings indicate that the most striking compositional and functional bacterial community changes took place during the active phase of the process. They also pinpoint functional attributes that may be related to the potential beneficial effects of distilled grape marc vermicompost when applied on soil and plants.
Geochronological, Geochemical and Sr-Nd-Hf Isotopic Studies of the A-type Granites and Adakitic Granodiorites in Western Junggar: Petrogenesis and Tectonic Implications
Authors: Lu Jia , Zhang Chen , Liu Dongdong
Published: April 2020

Late Carboniferous magmatism in the Western Junggar region of the Central Asian Orogenic Belt (CAOB) provides a critical geological record of regional tectonic and geodynamic history. In this study, we determined the zircon U-Pb isotopic compositions, bulk-rock Sr-Nd-Hf isotopic compositions, and major and trace element geochemistry of two granitic bodies in the Western Junggar, with the aim of constraining their emplacement ages, magmatic origin, and geodynamic significance. Radiometric ages indicate that the plutons were emplaced during the Late Carboniferous (322–307 Ma). Plutons in the North Karamay region are characterized by high Sr content (347–362 ppm) and low Y content (15.3–16.7 ppm), yielding relatively high Sr/Y ratios (20.8–23.7). They show consistent Yb (1.68–1.85 ppm), Cr (16–19 ppm), Co (7.5–8.1 ppm) and Ni (5.9–6.6 ppm) content, similar to that of modern adakites. The Hongshan plutons are characterized by high SiO2 (69.95–74.66 wt%), Na2O (3.26–3.64 wt%), and K2O (4.84–5.16 wt%) content, low Al2O3 (12.02–12.84 wt%;) and MgO (0.13–0 18 wt%) content, and low Mg# values (0.16–0.22). This group shows a clear geochemical affinity with A-type granites. All of the studied granitoids have positive εNd(t) (+4.89 to +7.21) and εHf(t) (+7.70 to +13.00) values, with young TDM(Nd) 806–526 Ma) and TDM(Hf) (656–383 Ma) ages, indicating a substantial addition of juvenile material. The adakitic granodiorites in the North Karamay region were likely generated via partial melting of thickened lower crust, while the A-type granites in the Hongshan area may have been derived from the melting of lower-middle crust in an intra-oceanic arc, which consists mainly of oceanic crust. The emplacement of these granitoids represents a regional magmatic “flare up”, which can be explained by the rollback of a subducting slab.
Mechanical and Thermal Properties of Polyether Polytriazole Elastomers Formed by Click-Chemical Reaction Curing Glycidyl Azide Polymer
Authors: He Liming , Zhou Jun , Wang Yutao , Ma Zhongliang , Chen Chunlin
Published: April 2020

Energetic binders are a research hot-spot, and much emphasis has been placed on their mechanical properties. In this study, propargyl-terminated ethylene oxide-tetrahydrofuran copolymer (PTPET) was synthesized. Then, PTPET and low-molecular-weight ester-terminated glycidyl azide polymer (GAP) were reacted by the click reaction without using catalysts to obtain a polyether polytriazole elastomer. Through tensile tests, where R = 0.5, the tensile strength reached 0.332 MPa, with an elongation at break of 897.1%. Swelling tests were used to measure the cross-linked network and showed that the cross-linked network regularity was reduced as R increased. The same conclusions were confirmed by dynamic mechanical analysis (DMA). In DMA curves, Tg was around −70 to −65 °C, and a small amount of crystallization appeared at between −50 and −30 °C, because locally ordered structures were also present in random copolymers, thereby forming localized crystals. Their thermal performance was tested by Differential Scanning Calorimeter (DSC) and Thermal Gravimetric Analyzer (TG), and the main mass loss occurred at around 350 to 450 °C, which meant that they were stable. In conclusion, the polyether polytriazole elastomer can be used as a binder in a composite propellant.
Effects of Graphene Oxide Nanofilm and Chicken Embryo Muscle Extract on Muscle Progenitor Cell Differentiation and Contraction
Authors: Bałaban Jaśmina , Wierzbicki Mateusz , Zielińska Marlena , Szczepaniak Jarosław , Sosnowska Malwina , Daniluk Karolina , Cysewski Dominik , Koczoń Piotr , Chwalibog André , Sawosz Ewa
Published: April 2020

Finding an effective muscle regeneration technique is a priority for regenerative medicine. It is known that the key factors determining tissue formation include cells, capable of proliferating and/or differentiating, a niche (surface) allowing their colonization and growth factors. The interaction between these factors, especially between the surface of the artificial niche and growth factors, is not entirely clear. Moreover, it seems that the use of a complex of complementary growth factors instead of a few strictly defined ones could increase the effectiveness of tissue maturation, including muscle tissue. In this study, we evaluated whether graphene oxide (GO) nanofilm, chicken embryo muscle extract (CEME), and GO combined with CEME would affect the differentiation and functional maturation of muscle precursor cells, as well as the ability to spontaneously contract a pseudo-tissue muscle. CEME was extracted on day 18 of embryogenesis. Muscle cells obtained from an 8-day-old chicken embryo limb bud were treated with GO and CEME. Cell morphology and differentiation were observed using different microscopy methods. Cytotoxicity and viability of cells were measured by lactate dehydrogenase and Vybrant Cell Proliferation assays. Gene expression of myogenic regulatory genes was measured by Real-Time PCR. Our results demonstrate that CEME, independent of the culture surface, was the main factor influencing the intense differentiation of muscle progenitor cells. The present results, for the first time, clearly demonstrated that the cultured tissue-like structure was capable of inducing contractions without externally applied impulses. It has been indicated that a small amount of CEME in media (about 1%) allows the culture of pseudo-tissue muscle capable of spontaneous contraction. The study showed that the graphene oxide may be used as a niche for differentiating muscle cells, but the decisive influence on the maturation of muscle tissue, especially muscle contractions, depends on the complexity of the applied growth factors.
Membrane Phospholipids and Polyphosphates as Cofactors and Binding Molecules of SERPINA12 (vaspin)
Authors: Tindall Catherine A. , Dommel Sebastian , Riedl Veronika , Ulbricht David , Hanke Stefanie , Sträter Norbert , Heiker John T.
Published: April 2020

Visceral adipose tissue derived serine protease inhibitor (vaspin) is a member of the serpin family and has been shown to have beneficial effects on glucose tolerance, insulin stability as well as adipose tissue inflammation, parameters seriously affected by obesity. Some of these effects require inhibition of target proteases such as kallikrein 7(KLK7) and many studies have demonstrated vaspin-mediated activation of intracellular signaling cascades in various cells and tissues. So far, little is known about the exact mechanism how vaspin may trigger these intracellular signaling events. In this study, we investigated and characterized the interaction of vaspin with membrane lipids and polyphosphates as well as their potential regulatory effects on serpin activity using recombinant vaspin and KLK7 proteins and functional protein variants thereof. Here, we show for the first time that vaspin binds to phospholipids and polyphosphates with varying effects on KLK7 inhibition. Vaspin binds strongly to monophosphorylated phosphatidylinositol phosphates (PtdInsP) with no effect on vaspin activation. Microscale thermophoresis (MST) measurements revealed high-affinity binding to polyphosphate 45 (KD: 466 ± 75 nM) and activation of vaspin in a heparin-like manner. Furthermore, we identified additional residues in the heparin binding site in β-sheet A by mutating five basic residues resulting in complete loss of high-affinity heparin binding. Finally, using lipid overlay assays, we show that these residues are additionally involved in PtdInsP binding. Phospholipids play a major role in membrane trafficking and signaling whereas polyphosphates are procoagulant and proinflammatory agents. The identification of phospholipids and polyphosphates as binding partners of vaspin will contribute to the understanding of vaspins involvement in membrane trafficking, signaling and beneficial effects associated with obesity.
Discovery of Novel Pyridazine-Based Cyclooxygenase-2 Inhibitors with a Promising Gastric Safety Profile
Authors: Khan Abida , Diwan Anupama , Thabet Hamdy Kh. , Imran Mohd , Bakht Md. Afroz
Published: April 2020

Cyclooxygenase-2 (COX-2) is implicated in the development of chronic inflammatory diseases. Recently, pyridazine derivatives have emerged as a novel prototype to develop COX-2 inhibitors. Accordingly, some pyridazine-based COX-2 inhibitors are reported herein. The reaction of aldehyde 3 and different hydrazines yielded the corresponding hydrazones. The hydrazones were further derivatized to the title compounds, which were assessed for COX-1 and COX-2 inhibitory action, gastric ulcerogenic effects, and lipid peroxidation properties. Molecular docking studies and determination of the physicochemical parameters were also carried out. The allocated structures of the reported compounds were coherent with their spectroscopic data. The compounds 9a (IC50 = 15.50 nM, 114.77%), 9b (IC50 = 17.50 nM, 101.65%), 12 (IC50 = 17.10 nM, 104.03%), 16b (IC50 = 16.90 nM, 105.26%), and 17 (IC50 = 17.70 nM, 100.5%) displayed better COX-2 inhibition than celecoxib (IC50 = 17.79 nM, 100%). These outcomes were harmonious with the molecular docking studies of 9a, 9b, 12, 16b, and 17. These compounds also displayed comparable onset and the duration of action concerning celecoxib and indomethacin in the in vivo studies. No ulcerogenic effects were observed for 9a and 12, whereas 9b, 16b, and 17 showed an insignificant ulcerogenic effect compared to celecoxib. The compounds 9a, 9b, 12, 16b, and 17 displayed a better lipid peroxidation profile than celecoxib and indomethacin. The compounds 9a (%ABS = 84.09), 9b (%ABS = 84.09), 12 (%ABS = 66.87), 16b (%ABS = 75.02), and 17 (%ABS = 81.42) also displayed appreciable calculated absorption compared to celecoxib (%ABS = 82.09). The compounds 9a, 9b, 11, 16b, and 17 have been recognized and postulated as non-ulcerogenic COX-2 inhibitors with promising physicochemical parameters and gastric safety profile. These compounds may be useful candidates to combat diseases caused by higher levels of COX-2.
On the Enhanced Accuracy of Kinetic Curve Building in Supercritical Fluid Extraction from Aroma Plants Using a New 3D-Printed Extract Collection Device
Authors: Prokopchuk Denis , Pokrovskiy Oleg
Published: April 2020

Accurate collection of extracted material represents a technical problem in supercritical fluid extraction because trapping should be performed in severe conditions of rapidly moving and freezing expanded fluid. We have developed a simple device for effective sample collection in analytical-scale supercritical fluid extraction. The device consists of a cyclone separator equipped with a spray trap and a heated check valve. The cyclone separator and spray trap are manufactured from a light polymer via 3D printing and are quick-detachable, which encourages its use in applications where mass yield measurements are required. The device was compared to a standard tubing-and-vial approach in the task of building kinetic curves for the extraction from two aroma plants, namely, laurel and rosemary. The new device showed almost two-fold increase in extraction trapping, most probably due to better collection of volatile compounds. A curious effect of the number of mass measurement points per curve on apparent yield was observed. An increase in the number of points led to an increase in yield, probably due to the effect of the static–dynamic extract regime posed by the manner in which the device is used.
Naked-Eye 3D Display Based on Microlens Array Using Combined Micro-Nano Imprint and UV Offset Printing Methods
Authors: Chen Linyi , Chen Guangxue , Liao Liyu , Chen Haozhi
Published: April 2020

An optical film integrating microlens array (MLAs) and 3D micro-graphics is an important way to achieve the naked-eye 3D display effect. The 3D micro-graphics is traditionally generated by the micro-nano imprint technology based on precision engraving mold, which leads to high production cost and low production efficiency, and thus restricts the rapid response to production tasks and large-scale popularization and application. In this study, a process scheme for large-scale printing of 3D micro-graphics using UV offset printing based on presensitized (PS) plate was proposed, matching with the MLAs fabricated by micro-nano imprint process to achieve naked-eye 3D display effect. We used the laser confocal microscope to systematically measure and analyze the geometric and optical performance of the fabricated MLAs in terms of height, curvature radius, center distance, spacing, focal length, and numerical aperture, and evaluated the influence of the publishing resolution of the PS plate on the display effect of 3D micro-graphics. The printing quality and display effect of 3D micro-graphics were further improved by adjusting process parameters such as printing speed and printing pressure. The results of the current study demonstrate that the combined application of micro-nano imprint technology based on precision mold and UV offset printing technology based on PS plate can achieve an excellent naked-eye 3D display effect in 360° all angles, which is efficient, cost-saving, and highly flexible.
Trypanocidal Activity of Four Sesquiterpene Lactones Isolated from Asteraceae Species
Authors: Elso Orlando G. , Bivona Augusto E. , Sanchez Alberti Andrés , Cerny Natacha , Fabian Lucas , Morales Celina , Catalán César A. N. , Malchiodi Emilio L. , Cazorla Silvia I. , Sülsen Valeria P.
Published: April 2020

The sesquiterpene lactones eupatoriopicrin, estafietin, eupahakonenin B and minimolide have been isolated from Argentinean Astearaceae species and have been found to be active against Trypanosoma cruzi epimastigotes. The aim of this work was to evaluate the activity of these compounds by analyzing their effect against the stages of the parasites that are infective for the human. Even more interesting, we aimed to determine the effect of the most active and selective compound on an in vivo model of T. cruzi infection. Eupatoriopicrin was the most active against amastigotes and tripomastigotes (IC50 = 2.3 µg/mL, and 7.2 µg/mL, respectively) and displayed a high selectivity index. This compound was selected to study on an in vivo model of T. cruzi infection. The administration of 1 mg/kg/day of eupatoriopicrin for five consecutive days to infected mice produced a significant reduction in the parasitaemia levels in comparison with non-treated animals (area under parasitaemia curves 4.48 vs. 30.47, respectively). Skeletal muscular tissues from eupatopicrin-treated mice displayed only focal and interstitial lymphocyte inflammatory infiltrates and small areas of necrotic; by contrast, skeletal tissues from T. cruzi infected mice treated with the vehicle showed severe lymphocyte inflammatory infiltrates with necrosis of the adjacent myocytes. The results indicate that eupatoriopicrin could be considered a promising candidate for the development of new therapeutic agents for Chagas disease.
Recent Progress of Cu-Catalyzed Azide-Alkyne Cycloaddition Reactions (CuAAC) in Sustainable Solvents: Glycerol, Deep Eutectic Solvents, and Aqueous Media
Authors: Nebra Noel , García-Álvarez Joaquín
Published: April 2020

This mini-review presents a general overview of the progress achieved during the last decade on the amalgamation of CuAAC processes (copper-catalyzed azide-alkyne cycloaddition) with the employment of sustainable solvents as reaction media. In most of the presented examples, the use of water, glycerol (Gly), or deep eutectic solvents (DESs) as non-conventional reaction media allowed not only to recycle the catalytic system (thus reducing the amount of the copper catalyst needed per mole of substrate), but also to achieve higher conversions and selectivities when compared with the reaction promoted in hazardous and volatile organic solvents (VOCs). Moreover, the use of the aforementioned green solvents also permits the improvement of the overall sustainability of the Cu-catalyzed 1,3-dipolar cycloaddition process, thus fulfilling several important principles of green chemistry.
Current Trends in the Application of Nanomaterials for the Removal of Emerging Micropollutants and Pathogens from Water
Authors: Kokkinos Petros , Mantzavinos Dionissios , Venieri Danae
Published: April 2020

Water resources contamination has a worldwide impact and is a cause of global concern. The need for provision of clean water is becoming more and more demanding. Nanotechnology may support effective strategies for the treatment, use and reuse of water and the development of next-generation water supply systems. The excellent properties and effectiveness of nanomaterials make them particularly suitable for water/wastewater treatment. This review provides a comprehensive overview of the main categories of nanomaterials used in catalytic processes (carbon nanotubes/graphitic carbon nitride (CNT/g-C3N4) composites/graphene-based composites, metal oxides and composites, metal–organic framework and commercially available nanomaterials). These materials have found application in the removal of different categories of pollutants, including pharmaceutically active compounds, personal care products, organic micropollutants, as well as for the disinfection of bacterial, viral and protozoa microbial targets, in water and wastewater matrices. Apart from reviewing the characteristics and efficacy of the aforementioned nanoengineered materials for the removal of different pollutants, we have also recorded performance limitations issues (e.g., toxicity, operating conditions and reuse) for their practical application in water and wastewater treatment on large scale. Research efforts and continuous production are expected to support the development of eco-friendly, economic and efficient nanomaterials for real life applications in the near future.
Phytocomplex Characterization and Biological Evaluation of Powdered Fruits and Leaves from Elaeagnus angustifolia
Authors: Carradori Simone , Cairone Francesco , Garzoli Stefania , Fabrizi Giancarlo , Iazzetti Antonia , Giusti Anna Maria , Menghini Luigi , Uysal Sengul , Ak Gunes , Zengin Gokhan , Cesa Stefania
Published: April 2020

Fully ripe fruits and mature leaves of Elaeagnus angustifolia were harvested and analyzed by means of analytical and biological tests to better comprehend the chemical composition and therapeutic/nutraceutical potential of this plant. Fruits and leaves were dried and the obtained powders were analyzed to study their color character and (via headspace gas chromatography) describe the chemical profile. Subsequently, they were submitted to a chloroform–methanol extraction, to a hydroalcoholic extraction procedure assisted or not by microwaves, and to an extraction with supercritical CO2, assisted or not by ethanol as the co-solvent, to detect the polyphenolic and the volatile content. The resulting extracts were evaluated in terms of chlorophyll and carotenoid content, polyphenolic content, volatile fraction, total phenolic content, total flavonoid content, antioxidant activity, radical scavenging activity, and enzymatic inhibition activity. The results confirmed the correlation between the chemical composition and the high antioxidant potential of leaf extracts compared to the fruit extracts in terms of the phenolic and pigment content. A promising effect against tyrosinase emerged for all the extracts, suggesting a therapeutic/nutraceutical use for this plant. Conversely, the volatile content from both natural matrices was similar.
A New Tetradentate Mixed Aza-Thioether Macrocycle and Its Complexation Behavior towards Fe(II), Ni(II) and Cu(II) Ions
Authors: Ng Sze-Wing , Chan Siu-Chung , Yeung Chi-Fung , Yiu Shek-Man , Wong Chun-Yuen
Published: April 2020

A new tetradentate mixed aza-thioether macrocyclic ligand 2,6-dithia[7](2,9)-1,10-phenanthrolinophane ([13]ane(phenN2)S2) was successfully synthesized. Reacting metal precursors [Fe(CH3CN)2(OTf)2], Ni(ClO4)2·6H2O, and Cu(ClO4)2·6H2O with one equivalent of [13]ane(phenN2)S2 afforded [Fe([13]ane(phenN2)S2)(OTf)2] (1), [Ni([13]ane(phenN2)S2)](ClO4)2 (2(ClO4)2), and [Cu([13]ane(phenN2)S2)(OH2)](ClO4)2 (3(ClO4)2), respectively. The structures of [13]ane(phenN2)S2 and all of its metal complexes were investigated by X-ray crystallography. The [13]ane(phenN2)S2 was found to behave as a tetradentate ligand via its donor atoms N and S.
Synthesis, Biological Evaluation and In Silico Studies of Certain Oxindole–Indole Conjugates as Anticancer CDK Inhibitors
Authors: Al-Warhi Tarfah , El Kerdawy Ahmed M. , Aljaeed Nada , Ismael Omnia E. , Ayyad Rezk R. , Eldehna Wagdy M. , Abdel-Aziz Hatem A. , Al-Ansary Ghada H.
Published: April 2020

On account of their overexpression in a wide range of human malignancies, cyclin-dependent kinases (CDKs) are among the most validated cancer targets, and their inhibition has been featured as a valuable strategy for anticancer drug discovery. In this study, a hybrid pharmacophore approach was adopted to develop two series of oxindole–indole conjugates (6a–i and 9a–f) and carbocycle–indole conjugates (11a,b) as efficient antitumor agents with potential inhibitory action toward CDK4. All oxindole–indole conjugates, except 6i, 9b, and 9c efficiently affected the growth of the human breast cancer MCF-7 (IC50: 0.39 ± 0.05–21.40 ± 1.58 μM) and/or MDA-MB-231 (IC50: 1.03 ± 0.04–22.54 ± 1.67 μM) cell lines, whereas bioisosteric replacement of the oxindole nucleus with indane or tetralin rings (compounds 11a,b) diminished the anti-proliferative activity. In addition, hybrids 6e and 6f displayed effective cell cycle disturbance and proapoptotic capabilities in MCF-7 cells. Furthermore, the efficient anti-proliferative agents towards MCF-7 and/or MDA-MB-231 cell lines (6a–h, 9a, and 9e) were investigated for their potential inhibitory action toward CDK4. Hybrids 6a and 6e displayed good CDK4 inhibitory activity with IC50s equal 1.82 and 1.26 µM, respectively. The molecular docking study revealed that oxindole moiety is implicated in two H-bonding interactions via both (NH) and (C=O) groups with the key amino acids Glu94 and Val96, respectively, whereas the indole framework is stably accommodated in a hydrophobic sub-pocket establishing hydrophobic interactions with the amino acid residues of Ile12, Val20, and Gln98 lining this sub-pocket. Collectively, these results highlighted hybrids 6a and 6e as good leads for further optimization as promising antitumor drugs toward breast malignancy and CDK inhibitors.