bluuebunny/crossref_metadata_2025 huggingface dataset:
Research on Formation Conditions of the Ultrafine-Grained Structure of the Cylindrical Parts Manufactured by Power Spinning Based on Small Strains
Authors: Xiao Gangfeng , Xia Qinxiang , Cheng Xiuquan , Chen Weiping
Published: October 2018

Two different methods, power spinning and annealing (PSA), quenching and power spinning followed by annealing (QPSA), for manufacturing the cylindrical parts with ultrafine-grained (UFG) structure were reviewed, the dislocation density and microstructural evolution during the two different processes of PSA and QPSA were further studied. The results show that the required strains for obtaining the UFG structure by power spinning is only 0.92 when the initial microstructure of the material is in the phase of lath martensite. The dislocation density and storage energy are increased to 10 times that of the blank after quenching and power spinning and decreased to the level of the blank after recrystallization annealing. Microstructures with fine grain size after quenching, storage energy of 1.8 × 105 kJ/m3 obtained after power spinning and second phase particle with nano-scale precipitated during annealing are the necessary formation conditions for manufacturing the cylindrical parts with UFG structure based on small strains. Compared with the original tubular blank, the mechanical properties of the spun parts with UFG structure improves significantly. The tensile strength and hardness of the spun parts manufactured by QPSA method is 815 MPa and 305 HV, respectively, and the elongation is 17.5%.
Metabolomic Investigations on Nesterenkonia flava Revealed Significant Differences between Marine and Terrestrial Actinomycetes
Authors: Xie Chun-Lan , Xia Jin-Mei , Wang Jun-Song , Lin Dong-Hai , Yang Xian-Wen
Published: October 2018

Marine microorganisms are an important source of natural products with potent bioactivities. Unlike the land, the ocean, especially the deep-sea, is characterized by high pressure, high salinity, low nutrition, and no light among others. Therefore, the biodiversity of marine microorganisms is supposed to be very different from that of the terrestrial ones. Yet, many marine microorganisms can find their counterparts in terrestrial environments. To evaluate their differences, a comparative metabolomics investigation was performed on four strains of Nesterenkonia flava isolated from terrestrial and marine environments. As a result, marine strains were clearly distinguished from terrestrial ones on the principal components analysis (PCA) score plot. Furthermore, by partial least squares discrimination analysis (PLS-DA) and univariate analysis, the characteristic metabolites were figured out and found to be involved in osmotic regulation, redox balancing, and energy metabolism. Our results demonstrated that marine actinomycetes could produce novel secondary metabolites different from their terrestrial relatives because they have special metabolic patterns closely related to the unique features of their living environment.
Peniginsengins B–E, New Farnesylcyclohexenones from the Deep Sea-Derived Fungus Penicillium sp. YPGA11
Authors: Cheng Zhongbin , Xu Wei , Liu Lijun , Li Shumin , Yuan Wangjun , Luo Zhuhua , Zhang Jingjie , Cheng Yongjun , Li Qin
Published: October 2018

Chemical examination of the EtOAc extract of the deep sea-derived fungus Penicillium sp. YPGA11 resulted in the isolation of four new farnesylcyclohexenones, peniginsengins B–E (1–4), and a known analog peniginsengin A (5). The structures of compounds 1–4 were determined on the basis of comprehensive analyses of the nuclear magnetic resonance (NMR) and mass spectroscopy (MS) data, and the absolute configurations of 1, 2, and 4 were determined by comparisons of experimental electronic circular dichroism (ECD) with calculated ECD spectra. Compounds 1–5, characterized by a highly oxygenated 1-methylcyclohexene unit and a (4E,8E)-4,8-dimethyldeca-4,8-dienoic acid side chain, are rarely found in nature. Compounds 2–4 exhibited antibacterial activity against Staphylococcus aureus.
Meroterpenoids and Isocoumarinoids from a Myrothecium Fungus Associated with Apocynum venetum
Authors: Xu Yanchao , Wang Cong , Liu Haishan , Zhu Guoliang , Fu Peng , Wang Liping , Zhu Weiming
Published: October 2018

Four new meroterpenoids 1–4 and four new isocoumarinoids 5–8, along with five known isocoumarinoids (9–13), were isolated from the fungus Myrothecium sp. OUCMDZ-2784 associated with the salt-resistant medicinal plant, Apocynum venetum (Apocynaceae). Their structures were elucidated by means of spectroscopic analysis, X-ray crystallography, ECD spectra and quantum chemical calculations. Compounds 1–5, 7, 9 and 10 showed weak α-glucosidase inhibition with the IC50 values of 0.50, 0.66, 0.058, 0.20, 0.32, 0.036, 0.026 and 0.37 mM, respectively.
Genetic Abnormalities, Clonal Evolution, and Cancer Stem Cells of Brain Tumors
Authors: Testa Ugo , Castelli Germana , Pelosi Elvira
Published: October 2018

Brain tumors are highly heterogeneous and have been classified by the World Health Organization in various histological and molecular subtypes. Gliomas have been classified as ranging from low-grade astrocytomas and oligodendrogliomas to high-grade astrocytomas or glioblastomas. These tumors are characterized by a peculiar pattern of genetic alterations. Pediatric high-grade gliomas are histologically indistinguishable from adult glioblastomas, but they are considered distinct from adult glioblastomas because they possess a different spectrum of driver mutations (genes encoding histones H3.3 and H3.1). Medulloblastomas, the most frequent pediatric brain tumors, are considered to be of embryonic derivation and are currently subdivided into distinct subgroups depending on histological features and genetic profiling. There is emerging evidence that brain tumors are maintained by a special neural or glial stem cell-like population that self-renews and gives rise to differentiated progeny. In many instances, the prognosis of the majority of brain tumors remains negative and there is hope that the new acquisition of information on the molecular and cellular bases of these tumors will be translated in the development of new, more active treatments.
Microstructures and Mechanical Properties of Mg-9Al/Ti Metallurgical Bonding Prepared by Liquid-Solid Diffusion Couples
Authors: Dai Jiahong , Jiang Bin , Yan Qiong , Xie Hongmei , Jiang Zhongtao , Yang Qingshan , Chen Qiaowang , Peng Cheng , Pan Fusheng
Published: October 2018

Microstructures and mechanical properties of Mg-9Al/Ti metallurgical bonding prepared by liquid-solid diffusion couples were investigated. The results indicate that a metallurgical bonding was formed at the interface Mg-9Al/Ti, and the Mg17Al12 phase growth coarsening at the interfaces with the increase in heat treatment time. Push-out testing was used to investigate the shear strength of the Mg-9Al/Ti metallurgical bonding. It is shown that the shear strength presents an increasing tendency with the increased heat treatment time. The sequence is characterized, and the results show that the fracture takes place along the Mg-9Al matrix at the interface. The diffusion of Al and Ti elements play a dominant role in the interface reaction of Mg-9Al/Ti metallurgical bonding. By energy-dispersive spectroscopy (EDS), X-ray diffraction (XRD) and thermodynamic analysis, it was found that Al3Ti is the only intermetallic compound at the interface of Mg-9Al/Ti metallurgical bonding. These results clearly show that chemical interaction at the interface formation of Al3Ti improves the mechanical properties of Mg-9Al/Ti metallurgical bonding.
Effects of Y, GdCu, and Al Addition on the Thermoelectric Behavior of CoCrFeNi High Entropy Alloys
Authors: Dong Wanqing , Zhou Zheng , Zhang Lijun , Zhang Mengdi , Liaw Peter K. , Li Gong , Liu Riping
Published: October 2018

Thermoelectric (TE) materials can interconvert waste heat into electricity, which will become alternative energy sources in the future. The high-entropy alloys (HEAs) as a new class of materials are well-known for some excellent properties, such as high friction toughness, excellent fatigue resistance, and corrosion resistance. Here, we present a series of HEAs to be potential candidates for the thermoelectric materials. The thermoelectric properties of YxCoCrFeNi, GdxCoCrFeNiCu, and annealed Al0.3CoCrFeNi were investigated. The effects of grain size and formation of the second phase on thermoelectric properties were revealed. In HEAs, we can reduce the thermal conductivity by controlling the phonon scattering due to the considerable complexity of the alloys. The Y, Gd-doped HEAs are competitive candidate thermoelectric materials for energy conversion in the future.
Microstructures and Mechanical Properties of a Laser-Welded Joint of Ti3Al-Nb Alloy Using Pure Nb Filler Metal
Authors: Wang Lin , Sun Daqian , Li Hongmei , Gu Xiaoyan , Shen Chengjie
Published: October 2018

Ti3Al-Nb alloy (Ti-24Al-15Nb) was welded by a pulsed laser welding system without and with pure Nb filler metal. The results indicated that pure Nb filler metal had profound effects on the microstructures and mechanical properties of the laser-welded joints. The joint without filler metal consisted of the weld zone (α’2 + B2), heat affected zone HAZ1 (α2 + B2), HAZ2 (α2 + O + B2) and base metal (α2 + O + B2), and gas pores were generated in the weld resulting in the deterioration of the joint strength (330 MPa) and elongation (1.9%). When the Nb filler metal was used, the weld microstructure (NbTi solid solution + O + B2) was obtained, and the joint properties were significantly improved, which was associated with the strengthening effect of the NbTi solid solution, O phase precipitation and the slip transmission between O and B2 phases, and the restraining of the formation of martensite (α’2) and gas pores in the weld. The strength (724 MPa) and elongation (5.1%) of the joint increased by 119.4% and 168.4% compared with those of the joint without filler metal, and the joint strength was able to reach 81.7% of the base metal strength (886 MPa). It is favorable to use pure Nb filler metal for improving the mechanical properties of laser-welded Ti3Al-Nb alloy joints.
Effect of Reinforcement Type and Dispersion on the Hardening of Sintered Pure Aluminium
Authors: Emadinia Omid , Vieira Maria , Vieira Manuel
Published: October 2018

The homogeneity of dispersion and reinforcing of pure aluminium by multi-walled carbon nanotubes (MWCNT) through the application of a high speed sonication (340 Hz) assisted by ultrasonication (35 kHz) was evaluated, this method was termed “assisted sonication”. Other reinforcements (graphene, nanoalumina, and ultrafine tungsten carbide) were used for comparison with the MWCNT. The hardness measurement enabled us to evaluate the strengthening effect of the reinforcements. Raman analysis was the technique selected to evaluate the integrity of MWCNTs during dispersion. The scanning and transmission electron microscopies revealed the dispersion and microstructure of the nanoreinforcements and nanocomposites. After applying the assisted sonication, the MWCNTs were detangled without exfoliation. The integrity of MWCNTs was strongly influenced by the presence of the aluminum powder during dispersion. The application of the assisted sonication method reduced the size of the aggregates in the matrix, in comparison with the sonication technique. Ultrafine tungsten carbide, with a 1 vol. %, was the reinforcement that more effectively hardened aluminum due to a good dispersion of the reinforcement, grain refinement and the formation of Al12W phase.
Passivity of Spring Steels with Compressive Residual Stress
Authors: Lee Kyu-Hyuk , Ahn Seung-Ho , Seo Ji-Won , Jang HeeJin
Published: October 2018

The electrochemical corrosion behavior and the semiconducting properties of the passive film formed on a coil spring steel were investigated in a buffer solution at pH 9. The anodic dissolution was mitigated, and the passive film grew faster for the spring steel with compressive residual stress than the one without stress. The passive films had an n-type semiconducting property with a high density of oxygen vacancy, and the defect density was lower for the specimens with compressive stress. The passive current density of the specimens with stress was higher and showed fluctuation. These characteristics imply that the growth mechanism of passive film and the transport of vacancies in the film on metals and alloys depend on the residual stress on the metallic surface.
Identifying Antibacterial Compounds in Black Walnuts (Juglans nigra) Using a Metabolomics Approach
Authors: Ho Khanh-Van , Lei Zhentian , Sumner Lloyd W. , Coggeshall Mark V. , Hsieh Hsin-Yeh , Stewart George C. , Lin Chung-Ho
Published: October 2018

Black walnut (Juglans nigra L.) is one of the most economically valuable hardwood species and a high value tree for edible nut production in the United States. Although consumption of black walnut has been linked to multiple health-promoting effects (e.g., antioxidant, antimicrobial, anti-inflammatory), the bioactive compounds have not been systematically characterized. In addition, the associations between different black walnut cultivars and their health-promoting compounds have not been well established. In this study, the kernels of twenty-two black walnut cultivars selected for nut production by the University of Missouri Center for Agroforestry (Columbia, MO, USA) were evaluated for their antibacterial activities using agar-well diffusion assay. Among the selected cultivars, four black walnut cultivars (i.e., Mystry, Surprise, D.34, and A.36) exhibited antibacterial activity against a Gram-positive bacterium (Staphylococcus aureus), whereas other cultivars showed no effect on the inhibition of this bacterium. The antibacterial compounds showing the strongest activity were isolated with bioassay-guided purification and identified using a metabolomics approach. Six antibacterial bioactive compounds responsible for antimicrobial activity were successfully identified. Glansreginin A, azelaic acid, quercetin, and eriodictyol-7-O-glucoside are novel antibacterial compounds identified in the kernels of black walnuts. The metabolomics approach provides a simple and cost-effective tool for bioactive compound identification.
Traceability of “Tuscan PGI” Extra Virgin Olive Oils by 1H NMR Metabolic Profiles Collection and Analysis
Authors: Girelli Chiara Roberta , Del Coco Laura , Zelasco Samanta , Salimonti Amelia , Conforti Francesca Luisa , Biagianti Andrea , Barbini Daniele , Fanizzi Francesco Paolo
Published: October 2018

According to Coldiretti, Italy still continues to hold the European Quality record in extra virgin olive oils with origin designation and protected geographical indication (PDO and PGI). To date, 46 Italian brands are recognized by the European Union: 42 PDO and 4 PGI (Tuscan PGI, Calabria PGI; Tuscia PGI and PGI Sicily). Specific regulations, introduced for these quality marks, include the designation of both the geographical areas and the plant varieties contributing to the composition of the olive oil. However, the PDO and PGI assessment procedures are currently based essentially on farmer declarations. Tuscan PGI extra virgin olive oil is one of the best known Italian trademarks around the world. Tuscan PGI varietal platform is rather wide including 31 specific olive cultivars which should account for at least 95% of the product. On the other hand, while the characteristics of other popular Italian extra virgin olive oils (EVOOs) cultivars from specific geographical areas have been extensively studied (such as those of Coratina based blends from Apulia), little is still known about Tuscan PGI EVOO constituents. In this work, we performed, for the first time, a large-scale analysis of Tuscan PGI monocultivar olive oils by 1H NMR spectroscopy and multivariate statistical analyses (MVA). After genetic characterization of 217 leaf samples from 24 selected geographical areas, distributed all over the Tuscany, a number of 202 micro-milled oil samples including 10 PGI cultivars, was studied. The results of the present work confirmed the need of monocultivar genetically certified EVOO samples for the construction of 1H-NMR-metabolic profiles databases suitable for cultivar and/or geographical origin assessment. Such specific PGI EVOOs databases could be profitably used to justify the high added value of the product and the sustainability of the related supply chain.
Shear Mode Bulk Acoustic Resonator Based on Inclined c-Axis AlN Film for Monitoring of Human Hemostatic Parameters
Authors: Song Shuren , Chen Da , Wang Hongfei , Li Chaohui , Wang Wei , Yu Wangli , Wang Yanyan , Guo Qiuquan
Published: October 2018

Measurement of hemostatic parameters is essential for patients receiving long-term oral anticoagulant agents. In this paper, we present a shear mode bulk acoustic resonator based on an inclined c-axis aluminum nitride (AlN) film for monitoring the human hemostatic parameters. During the blood coagulation process, the resonant frequency of the device decreases along with a step-ladder profile due to the viscosity change during the formation of fibers in blood, revealing the sequential coagulation stages. Two hemostatic parameters with clinical significance, prothrombin time (PT) along with its derived measure of international normalized ratio (INR), are determined from time-frequency curves of the device. Furthermore, the resonator is compared with a commercial coagulometer by monitoring the hemostatic parameters for one month in a patient taking the oral anticoagulant. The results are consistent. In addition, thanks to the excellent potential for integration, miniaturization and the availability of direct digital signals, the proposed device has promising application for point of care coagulation monitoring.
Fabrication of a Malaria-Ab ELISA Bioassay Platform with Utilization of Syringe-Based and 3D Printed Assay Automation
Authors: Lim Christopher , Lee Yangchung , Kulinsky Lawrence
Published: October 2018

We report on the fabrication of a syringe-based platform for automation of a colorimetric malaria-Ab assay. We assembled this platform from inexpensive disposable plastic syringes, plastic tubing, easily-obtainable servomotors, and an Arduino microcontroller chip, which allowed for system automation. The automated system can also be fabricated using stereolithography (SLA) to print elastomeric reservoirs (used instead of syringes), while platform framework, including rack and gears, can be printed with fused deposition modeling (FDM). We report on the optimization of FDM and SLA print parameters, as well as post-production processes. A malaria-Ab colorimetric test was successfully run on the automated platform, with most of the assay reagents dispensed from syringes. Wash solution was dispensed from an SLA-printed elastomeric reservoir to demonstrate the feasibility of both syringe and elastomeric reservoir-based approaches. We tested the platform using a commercially available malaria-Ab colorimetric assay originally designed for spectroscopic plate readers. Unaided visual inspection of the assay solution color change was sufficient for qualitative detection of positive and negative samples. A smart phone application can also be used for quantitative measurement of the assay color change.
A Metabolomic-Based Evaluation of the Role of Commensal Microbiota throughout the Gastrointestinal Tract in Mice
Authors: Yamamoto Yuri , Nakanishi Yumiko , Murakami Shinnosuke , Aw Wanping , Tsukimi Tomoya , Nozu Ryoko , Ueno Masami , Hioki Kyoji , Nakahigashi Kenji , Hirayama Akiyoshi , Sugimoto Masahiro , Soga Tomoyoshi , Ito Mamoru , Tomita Masaru , Fukuda Shinji
Published: October 2018

Commensal microbiota colonize the surface of our bodies. The inside of the gastrointestinal tract is one such surface that provides a habitat for them. The gastrointestinal tract is a long organ system comprising of various parts, and each part possesses various functions. It has been reported that the composition of intestinal luminal metabolites between the small and large intestine are different; however, comprehensive metabolomic and commensal microbiota profiles specific to each part of the gastrointestinal lumen remain obscure. In this study, by using capillary electrophoresis time-of-flight mass spectrometry (CE-TOFMS)-based metabolome and 16S rRNA gene-based microbiome analyses of specific pathogen-free (SPF) and germ-free (GF) murine gastrointestinal luminal profiles, we observed the different roles of commensal microbiota in each part of the gastrointestinal tract involved in carbohydrate metabolism and nutrient production. We found that the concentrations of most amino acids in the SPF small intestine were higher than those in the GF small intestine. Furthermore, sugar alcohols such as mannitol and sorbitol accumulated only in the GF large intestine, but not in the SPF large intestine. On the other hand, pentoses, such as arabinose and xylose, gradually accumulated from the cecum to the colon only in SPF mice, but were undetected in GF mice. Correlation network analysis between the gastrointestinal microbes and metabolites showed that niacin metabolism might be correlated to Methylobacteriaceae. Collectively, commensal microbiota partially affects the gastrointestinal luminal metabolite composition based on their metabolic dynamics, in cooperation with host digestion and absorption.
Sorption of Differently Charged Gold Nanoparticles on Synthetic Pyrite
Authors: Luo Suxing , Nie Xin , Yang Meizhi , Fu Yuhong , Zeng Ping , Wan Quan
Published: October 2018

Sorption of nanoparticles on mineral surfaces has been well recognized for its environmental implication. For certain gold ore deposits, sorption of gold nanoparticles (AuNPs) on pyrite may constitute a critical step in the metallogenesis process, yet it has not been adequately investigated. In this work, we synthesized negatively charged, positively charged AuNPs and pyrite respectively, and experimentally studied sorption of AuNPs on pyrite in an anaerobic environment. The effects of AuNPs charge characteristics, pH, hexadecyl trimethyl ammonium bromide (CTAB) concentration, and ionic strength were evaluated. For the negatively charged AuNPs, almost no sorption was observed owing to the electrostatic repulsion between the AuNPs and pyrite surface (with a measured isoelectric point of 2.0). In contrast, positively charged AuNPs could be significantly adsorbed on pyrite through electrostatic attraction, with the sorption extent decreasing with the increase of pH (2.2–9.1). However, the adsorption of CTAB from the solution was found to increase with the increase of pH. Furthermore, deliberately added CTAB seemed to inhibit the sorption of AuNPs. Our study not only demonstrates that the electrostatic interaction is the dominant mechanism in the sorption of AuNPs on pristine pyrite, but also reveals the important competitive relation between AuNPs and CTAB in the sorption process.
Control of Shear-Zone-Induced Pressure Fluctuations on Gold Endowment: The Giant El Callao District, Guiana Shield, Venezuela
Authors: Velásquez German , Salvi Stefano , Siebenaller Luc , Béziat Didier , Carrizo Daniel
Published: October 2018

The El Callao district, with a total endowment of more than 2000 t Au, is considered to be the most prolific gold resource in Venezuela. Mineralization is hosted by a vein system that is genetically associated with the El Callao transpressional shear zone. This vein system consists of a network of interconnected quartz–albite–ankerite veins enveloping a large number of metabasaltic fragments that host gold-bearing pyrites. Based on detailed mineralogical, microstructural, and fluid inclusion studies, a pressure-temperature pathway was established for the evolution of the mineralizing fluid during shear-zone development and exhumation. This path is characterized by repeated episodes of fluid pressure fluctuation from lithostatic (higher than 1.6 kbar) to near-hydrostatic values (<0.4 kbar), recorded throughout the transition from the quasi-plastic to frictional deformation cortical domains. Each successive pressure drop induced boiling of the hydrothermal fluid, with the resulting fluid phase separation controlling: (i) pyrite and invisible gold crystallization, which occurred during ductile and ductile-brittle transition strain conditions, and (ii) primary gold remobilization with consequent native-refined gold precipitation, occurring mainly under brittle conditions. The metallogenic framework that was proposed for the El Callao shear zone can be used as a vector to explore and characterize other mineralized shear zones in the Guiana Shield and analogous orogenic systems worldwide.
Deciphering Silicification Pathways of Fossil Forests: Case Studies from the Late Paleozoic of Central Europe
Authors: Trümper Steffen , Rößler Ronny , Götze Jens
Published: October 2018

The occurrence and formation of silicified wood from five late Paleozoic basins in Central Europe was investigated. Fossil wood from diverse geological settings was studied using field observations, taphonomic determinations as well as mineralogical analyses (polarizing microscopy, cathodoluminescence (CL) microscopy and spectroscopy). The results indicate that silicification is either a monophase or multiphase process under varying physico-chemical conditions. In particular, CL studies revealed complex processes of silica accumulation and crystallization. The CL characteristics of quartz phases in silicified wood can mostly be related to blue (390 and 440 nm), yellow (580 nm), and red (650 nm) emission bands, which may appear in different combinations and varying intensity ratios. Yellow CL is typical for initial silicification, reflecting quick precipitation under oxygen-deficient conditions caused by initial decay of the organic material. Blue CL is predominantly of secondary origin, resulting from replacement of precursor phases by a secondary hydrothermal quartz generation or subsequent silicification of wood. The red CL can be related to a lattice defect (non-bridging oxygen hole center—NBOHC).
Assessing the Similarity of Cyanide-Free Gold Leaching Processes: A Case-Based Reasoning Application
Authors: Leikola Maria , Sauer Christian , Rintala Lotta , Aromaa Jari , Lundström Mari
Published: October 2018

Hydrometallurgical researchers, and other professionals alike, invest significant amounts of time reading scientific articles, technical notes, and other scientific documents, while looking for the most relevant information for their particular research interest. In an attempt to save the researcher’s time, this study presents an information retrieval tool using case-based reasoning. The tool was built for comparing scientific articles concerning cyanide-free leaching of gold ores/concentrates/tailings. Altogether, 50 cases of experiments were gathered in a case base. 15 different attributes related to the treatment of the raw material and the leaching conditions were selected to compare the cases. The attributes were as follows: Pretreatment, Overall method, Complexant source, Oxidant source, Complexant concentration, Oxidant concentration, Temperature, pH, Redox-potential, Pressure, Materials of construction, Extraction, Extraction rate, Reagent consumption, and Solid-liquid ratio. The resulting retrieval tool (LeachSim) was able to rank the scientific articles according to their similarity with the user’s research interest. Such a tool could eventually aid the user in finding the most relevant information, but not replace thorough understanding and human expertise.
Ab Initio Molecular Dynamics Simulation Study on the Stereo Reactions between Atomic Oxygen Anion and Methane
Authors: Wang Weihua , Feng Wenling , Wang Wenliang , Li Ping
Published: October 2018

Ion–molecule reaction between atomic oxygen anion (O−) and methane (CH4) has been systematically investigated employing the on-the-fly ab initio molecular dynamics simulations. Besides the major H-abstraction process as the exothermic reaction studied widely, an endothermic pathway to produce OCH3− and H is also observed in this study. Three typical O− attack modes with reference to the pyramid structure of CH4 fixed in space have been considered. It was found that the internal motions of the radical products are significantly dependent on the O− attack modes. As for the reaction between O− and the thermally vibrating CH4, the major pathway to produce OH− and CH3 is preferred by the direct H-abstraction and the minor pathway to produce H and OCH3− is the roaming reaction via the transient negative ion [HO-CH3]−.
Quantification and Confirmation of Fifteen Carbamate Pesticide Residues by Multiple Reaction Monitoring and Enhanced Product Ion Scan Modes via LC-MS/MS QTRAP System
Authors: Zhou Ying , Guan Jian , Gao Weiwei , Lv Shencong , Ge Miaohua
Published: October 2018

In this research, fifteen carbamate pesticide residues were systematically analyzed by ultra-high performance liquid chromatography–quadrupole-linear ion trap mass spectrometry on a QTRAP 5500 system in both multiple reaction monitoring (MRM) and enhanced product ion (EPI) scan modes. The carbamate pesticide residues were extracted from a variety of samples by QuEChERS method and separated by a popular reverse phase column (Waters BEH C18). Except for the current conformation criteria including selected ion pairs, retention time and relative intensities from MRM scan mode, the presence of carbamate pesticide residues in diverse samples, especially some doubtful cases, could also be confirmed by the matching of carbamate pesticide spectra via EPI scan mode. Moreover, the fragmentation routes of fifteen carbamates were firstly explained based on the mass spectra obtained by a QTRAP system; the characteristic fragment ion from a neutral loss of CH3NCO (−57 Da) could be observed. The limits of detection and quantification for fifteen carbamates were 0.2–2.0 μg kg−1 and 0.5–5.0 μg kg−1, respectively. For the intra- (n = 3) and inter-day (n = 15) precisions, the recoveries of fifteen carbamates from spiked samples ranged from 88.1% to 118.4%, and the coefficients of variation (CVs) were all below 10%. The method was applied to pesticide residues detection in fruit, vegetable and green tea samples taken from local markets, in which carbamates were extensively detected but all below the standard of maximum residue limit.
Chemical Composition of Myrtle (Myrtus communis L.) Berries Essential Oils as Observed in a Collection of Genotypes
Authors: Usai Marianna , Marchetti Mauro , Culeddu Nicola , Mulas Maurizio
Published: October 2018

Myrtle (Myrtus communis L.) is a shrub spontaneously growing in the Mediterranean area. The leaf and fruit content of essential oils and phenolic compounds justify the wide use of the plant as medicinal and aromatic. Because of overexploitation of wild plants, a domestication process is in progress in different regions and the influence of the genotype variability on the chemical composition of fruit essential oils may be useful to breeding programs. Consequently, the analysis performed on a selected group of candidate clones growing in the same field collection in Sardinia is the object of this report. Forty-seven selections provided fully ripe fruits for essential oil extraction by hydrodistillation and Gas Chromatography-Mass Spectrometry (GC-MS) analysis. Only five candidate clones showed white fruits. The highest yield of essential oil was observed in the LAC31 genotype with 0.55 g·kg−1, while the samples BOS1, MON5, RUM4, RUM10, V4 and V8 showed values above 0.20 g·kg−1 and most of the genotypes under 0.10 g·kg−1. Geranyl acetate was the compound with the highest relative abundance. The second compound for relative abundance was the 1,8-cineole. Other compounds with high relative abundance were α-terpinyl acetate, methyleugenol, linalool, α-terpineol, β-caryophyllene, α-humulene, Trans-caryophyllene oxide, and humulene epoxide II.
A Unique Naphthone Derivative and a Rare 4,5-seco-Lanostane Triterpenoid from Poria cocos
Authors: Chen Ting , Hua La , Chou Guixin , Mao Xudong , Zou Xianliang
Published: October 2018

A previously undescribed naphthalenone derivative, sohiracillinone (1), and a novel 4,5-seco-lanostane triterpenoid, 11β-ethoxydaedaleanic acid A (2) were isolated with two new lanostane triterpenoids, ceanphytamic acids A (3) and B (4), from the EtOH extract of Poria cocos along with 17 known compounds 5–21. The absolute configuration of sohiracillinone (1) was unambiguously identified by NMR and electronic circular dichroism (ECD) data. The structures of other new compounds were elucidated on the basis of NMR and mass spectroscopy (MS), and the cytotoxic activities of all the isolated components were evaluated.
Hits-to-Lead Optimization of the Natural Compound 2,4,6-Trihydroxy-3-geranyl-acetophenone (tHGA) as a Potent LOX Inhibitor: Synthesis, Structure-Activity Relationship (SAR) Study, and Computational Assignment
Authors: Ng Chean Hui , Rullah Kamal , Abas Faridah , Lam Kok Wai , Ismail Intan Safinar , Jamaludin Fadzureena , Shaari Khozirah
Published: October 2018

A new series of 2,4,6-trihydroxy-3-geranyl-acetophenone (tHGA) analogues were synthesized and evaluated for their lipoxygenase (LOX) inhibitory activity. Prenylated analogues 4a–g (half maximal inhibitory concentration (IC50) values ranging from 35 μ M to 95 μ M) did not exhibit better inhibitory activity than tHGA (3a) (IC50 value: 23.6 μ M) due to the reduction in hydrophobic interaction when the alkyl chain length was reduced. One geranylated analogue, 3d, with an IC50 value of 15.3 μ M, exhibited better LOX inhibitory activity when compared to tHGA (3a), which was in agreement with our previous findings. Kinetics study showed that the most active analogue (3e) and tHGA (3a) acted as competitive inhibitors. The combination of in silico approaches of molecular docking and molecular dynamic simulation revealed that the lipophilic nature of these analogues further enhanced the LOX inhibitory activity. Based on absorption, distribution, metabolism, excretion, and toxicity (ADMET) and toxicity prediction by komputer assisted technology (TOPKAT) analyses, all geranylated analogues (3a–g) showed no hepatotoxicity effect and were biodegradable, which indicated that they could be potentially safe drugs for treating inflammation.
New N-(oxazolylmethyl)-thiazolidinedione Active against Candida albicans Biofilm: Potential Als Proteins Inhibitors
Authors: Marc Gabriel , Araniciu Cătălin , Oniga Smaranda Dafina , Vlase Laurian , Pîrnău Adrian , Duma Mihaela , Măruțescu Luminița , Chifiriuc Mariana Carmen , Oniga Ovidiu
Published: October 2018

C. albicans is the most frequently occurring fungal pathogen, and is becoming an increasing public health problem, especially in the context of increased microbial resistance. This opportunistic pathogen is characterized by a versatility explained mainly by its ability to form complex biofilm structures that lead to enhanced virulence and antibiotic resistance. In this context, a review of the known C. albicans biofilm formation inhibitors were performed and a new N-(oxazolylmethyl)-thiazolidinedione scaffold was constructed. 16 new compounds were synthesized and characterized in order to confirm their proposed structures. A general antimicrobial screening against Gram-positive and Gram-negative bacteria, as well as fungi, was performed and revealed that the compounds do not have direct antimicrobial activity. The anti-biofilm activity evaluation confirmed the compounds act as selective inhibitors of C. albicans biofilm formation. In an effort to substantiate this biologic profile, we used in silico investigations which suggest that the compounds could act by binding, and thus obstructing the functions of, the C. albicans Als surface proteins, especially Als1, Als3, Als5 and Als6. Considering the well documented role of Als1 and Als3 in biofilm formation, our new class of compounds that target these proteins could represent a new approach in C. albicans infection prevention and management.
Establishing the Phenolic Composition of Olea europaea L. Leaves from Cultivars Grown in Morocco as a Crucial Step Towards Their Subsequent Exploitation
Authors: Olmo-García Lucía , Bajoub Aadil , Benlamaalam Sara , Hurtado-Fernández Elena , Bagur-González María Gracia , Chigr Mohammed , Mbarki Mohamed , Fernández-Gutiérrez Alberto , Carrasco-Pancorbo Alegría
Published: October 2018

In Morocco, the recovery of olive agro-industrial by-products as potential sources of high-added value substances has been underestimated so far. A comprehensive quantitative characterization of olive leaves’ bioactive compounds is crucial for any attempt to change this situation and to implement the valorization concept in emerging countries. Thus, the phenolic fraction of olive leaves of 11 varieties (‘Arbequina’, ‘Hojiblanca’, ‘Frantoio’, ‘Koroneiki’, ‘Lechín’, ‘Lucque’, ‘Manzanilla’, ‘Picholine de Languedoc’, ‘Picholine Marocaine’, ‘Picual’ and ‘Verdal’), cultivated in the Moroccan Meknès region, was investigated. Thirty eight phenolic or related compounds (including 16 secoiridoids, nine flavonoids in their aglycone form, seven flavonoids in glycosylated form, four simple phenols, one phenolic acid and one lignan) were determined in a total of 55 samples by using ultrasonic-assisted extraction and liquid chromatography coupled to electrospray ionization-ion trap mass spectrometry (LC-ESI-IT MS). Very remarkable quantitative differences were observed among the profiles of the studied cultivars. ‘Picholine Marocaine’ variety exhibited the highest total phenolic content (around 44 g/kg dry weight (DW)), and logically showed the highest concentration in terms of various individual compounds. In addition, chemometrics (principal components analysis (PCA) and stepwise-linear discriminant analysis (s-LDA)) were applied to the quantitative phenolic compound data, allowing good discrimination of the selected samples according to their varietal origin.
Incorporation of PVDF Nanofibre Multilayers into Functional Structure for Filtration Applications
Authors: Roche Remi , Yalcinkaya Fatma
Published: October 2018

Membranes are considered as a promising technology for separation and filtration processes. Here, novel polyvinylidene fluoride (PVDF) nanofibrous multilayer membranes were fabricated by wire-based industrial electrospinning equipment following by a lamination process. The lamination process was optimised under various applied temperature, force of lamination, and lamination time. Air permeability and burst-pressure tests were run to determine the optimum membranes for filtration application. The structures of the prepared membranes were characterised by scanning electron microscopy and pore-size analysis. The hydrophilic properties of the membranes were evaluated using water contact angle measurement, and the mechanical strength of the membranes was analysed. Air and water filtration tests were run to find the possible application of prepared membranes. The air filtration results showed that membranes had high filtration efficiencies: Over 99.00% for PM2.5, and PM0.1. The water filtration results indicated that permeability of the membranes changed from 288 to 3275 L/m2hbar. The successful preparation of such an interesting material may provide a new approach for the design and development of electrospun filter membranes.
Hierarchical Structure and Catalytic Activity of Flower-Like CeO2 Spheres Prepared Via a Hydrothermal Method
Authors: Shen Genli , Liu Mi , Wang Zhen , Wang Qi
Published: October 2018

Hierarchical CeO2 particles were synthesized by a hydrothermal method based on the reaction between CeCl3·7H2O and PVP at 270 °C. The flower-like CeO2 with an average diameter of about 1 μm is composed of compact nanosheets with thicknesses of about 15 nm and have a surface area of 36.8 m2/g, a large pore volume of 0.109 cm3/g, and a narrow pore size distribution (14.9 nm in diameter). The possible formation mechanism of the hierarchical CeO2 nanoparticles has been illustrated. The 3D hierarchical structured CeO2 exhibited a higher catalytic activity toward CO oxidation compared with commercial CeO2.
Photo-Magnetic Irradiation-Mediated Multimodal Therapy of Neuroblastoma Cells Using a Cluster of Multifunctional Nanostructures
Authors: Atluri Rohini , Atmaramani Rahul , Tharaka Gamage , McCallister Thomas , Peng Jian , Diercks David , GhoshMitra Somesree , Ghosh Santaneel
Published: October 2018

The use of high intensity chemo-radiotherapies has demonstrated only modest improvement in the treatment of high-risk neuroblastomas. Moreover, undesirable drug specific and radiation therapy-incurred side effects enhance the risk of developing into a second cancer at a later stage. In this study, a safer and alternative multimodal therapeutic strategy involving simultaneous optical and oscillating (AC, Alternating Current) magnetic field stimulation of a multifunctional nanocarrier system has successfully been implemented to guide neuroblastoma cell destruction. This novel technique permitted the use of low-intensity photo-magnetic irradiation and reduced the required nanoparticle dose level. The combination of released cisplatin from the nanodrug reservoirs and photo-magnetic coupled hyperthermia mediated cytotoxicity led to the complete ablation of the B35 neuroblastoma cells in culture. Our study suggests that smart nanostructure-based photo-magnetic hybrid irradiation is a viable approach to remotely guide neuroblastoma cell destruction, which may be adopted in clinical management post modification to treat aggressive cancers.
Phosphoric Acid Doped Polybenzimidazole (PBI)/Zeolitic Imidazolate Framework Composite Membranes with Significantly Enhanced Proton Conductivity under Low Humidity Conditions
Authors: Escorihuela Jorge , Sahuquillo Óscar , García-Bernabé Abel , Giménez Enrique , Compañ Vicente
Published: October 2018

The preparation and characterization of composite polybenzimidazole (PBI) membranes containing zeolitic imidazolate framework 8 (ZIF-8) and zeolitic imidazolate framework 67 (ZIF-67) is reported. The phosphoric acid doped composite membranes display proton conductivity values that increase with increasing temperatures, maintaining their conductivity under anhydrous conditions. The addition of ZIF to the polymeric matrix enhances proton transport relative to the values observed for PBI and ZIFs alone. For example, the proton conductivity of PBI@ZIF-8 reaches 3.1 × 10−3 S·cm−1 at 200 °C and higher values were obtained for PBI@ZIF-67 membranes, with proton conductivities up to 4.1 × 10−2 S·cm−1. Interestingly, a composite membrane containing a 5 wt.% binary mixture of ZIF-8 and ZIF-67 yielded a proton conductivity of 9.2 × 10−2 S·cm−1, showing a synergistic effect on the proton conductivity.
PEGylation of Superparamagnetic Iron Oxide Nanoparticles with Self-Organizing Polyacrylate-PEG Brushes for Contrast Enhancement in MRI Diagnosis
Authors: Illés Erzsébet , Szekeres Márta , Tóth Ildikó Y. , Farkas Katalin , Földesi Imre , Szabó Ákos , Iván Béla , Tombácz Etelka
Published: October 2018

For biomedical applications, superparamagnetic nanoparticles (MNPs) have to be coated with a stealth layer that provides colloidal stability in biological media, long enough persistence and circulation times for reaching the expected medical aims, and anchor sites for further attachment of bioactive agents. One of such stealth molecules designed and synthesized by us, poly(polyethylene glycol methacrylate-co-acrylic acid) referred to as P(PEGMA-AA), was demonstrated to make MNPs reasonably resistant to cell internalization, and be an excellent candidate for magnetic hyperthermia treatments in addition to possessing the necessary colloidal stability under physiological conditions (Illés et al. J. Magn. Magn. Mater. 2018, 451, 710–720). In the present work, we elaborated on the molecular background of the formation of the P(PEGMA-AA)-coated MNPs, and of their remarkable colloidal stability and salt tolerance by using potentiometric acid–base titration, adsorption isotherm determination, infrared spectroscopy (FT-IR ATR), dynamic light scattering, and electrokinetic potential determination methods. The P(PEGMA-AA)@MNPs have excellent blood compatibility as demonstrated in blood sedimentation, smears, and white blood cell viability experiments. In addition, blood serum proteins formed a protein corona, protecting the particles against aggregation (found in dynamic light scattering and electrokinetic potential measurements). Our novel particles also proved to be promising candidates for MRI diagnosis, exhibiting one of the highest values of r2 relaxivity (451 mM−1s−1) found in literature.
Structural and Magnetic Properties of Ni0.8Fe0.2/Ti Nanoscale Multilayers
Authors: Antón Ricardo López , González Juan A. , Andrés Juan P. , Svalov Andrei V. , Kurlyandskaya Galina V.
Published: October 2018

The influence of the thickness of the Ni0.8Fe0.2 (Permalloy, Py) layers on the structural and magnetic properties of magnetron sputtered Py/Ti multilayers was studied. The thickness of the Py layers was varied in the interval of 8 to 30 Å. X-ray reflectivity scans evidence the existence of a well-defined layered structure in all the samples considered, but also the presence of a complex intermixed interface. The shape of both the temperature dependence of magnetization and the hysteresis loops of the multilayered structures depends strongly on Py thickness. Magnetic and reflectivity measurements were comparatively analyzed in order to better understand the structure of the samples, and specifically, their interfaces. In particular, the presence of small superparamagnetic Py at the interfaces of the samples, especially evident in the samples with the thinnest Py layers, seems confirmed by the magnetic measurements, agreeing well with the reflectivity results.
Resistance of Superhydrophobic Surface-Functionalized TiO2 Nanotubes to Corrosion and Intense Cavitation
Authors: Hua Weidi , Kar Piyush , Roy Partha , Bu Lintong , Shoute Lian , Kumar Pawan , Shankar Karthik
Published: October 2018

The availability of robust superhydrophobic materials with the ability to withstand harsh environments are in high demand for many applications. In this study, we have presented a simple method to fabricate superhydrophobic materials from TiO2 nanotube arrays (TNTAs) and investigated the resilience of the materials when they are subjected to harsh conditions such as intense cavitation upon ultrasonication, corrosion in saline water, water-jet impact, and abrasion. The TNTAs were prepared by anodization of Ti foil in buffered aqueous electrolyte containing fluoride ions. The hydrophilic TNTAs were functionalized with octadecylphosphonic acid (ODPA) or 1H, 1H′, 2H, 2H′-perfluorodecyl phosphonic acid (PFDPA) to form a self-assembled monolayer on the TNTA surface to produce superhydrophobic ODPA@TNTA or PFDPA@TNTA surfaces. The superhydrophobic ODPA@TNTA and PFDPA@TNTA have contact angles of 156.0° ± 1.5° and 168° ± 1.5°, and contact angle hysteresis of 3.0° and 0.8°, respectively. The superhydrophobic ODPA@TNTA and PFDPA@TNTA were subjected to ultrasonication, corrosion in saline water, and water-jet impact and abrasion, and the resilience of the systems was characterized by electrochemical impedance spectroscopy (EIS), contact angle (CA) measurements, diffuse reflectance Fourier transform infrared spectroscopy (DRIFTS), and field-emission scanning electron microscopy (FESEM). The results presented here show that superhydrophobic ODPA@TNTA and PFDPA@TNTA are robust and resilient under the harsh conditions studied in this work, and indicate the potential of these materials to be deployed in practical applications.