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Frontiers in Chemistry

Zia Uddin, Yeong Hun Song, Mahboob Ullah, Zuopeng Li, Jeong Yoon Kim, Ki Hun Park
Diabetes mellitus is one of a major worldwide concerns, regulated by either defects in secretion or action of insulin, or both. Insulin signaling down-regulation has been related with over activity of protein tyrosine phosphatase 1B (PTP1B) enzyme, which has been a promising target for the treatment of diabetes mellitus. Herein, activity guided separation of methanol extract (95%) of Dodonaea viscosa aerial parts afforded nine ( 1 - 9 ) polyphenolic compounds, all of them were identified through spectroscopic data including 2D NMR and HREIMS...
2018: Frontiers in Chemistry
Wei Guan, Gaoge Sun, Lei Yin, Zhenghua Zhang, Shichao Tian
The oxidation of hypophosphite to phosphate is the key to recover the phosphorus resource from the hypophosphite wastewater. In the present work, Ti4 O7 /g-C3 N4 composites were synthesized at two different temperatures (100 and 160°C) and their performance on photocatalytic oxidation of hypophosphite under visible light irradiation and the corresponding mechanism were evaluated. A hydrolysis method using g-C3 N4 and Ti4 O7 was applied to synthesize the Ti4 O7 /g-C3 N4 composites with their hybrid structure and morphology confirmed by X-ray diffraction (XRD), scanning electron microscopy (SEM), and X-ray photoelectron spectra (XPS)...
2018: Frontiers in Chemistry
Miloslav Pekař
Recently, a method based on non-equilibrium continuum thermodynamics which derives thermodynamically consistent reaction rate models together with thermodynamic constraints on their parameters was analyzed using a triangular reaction scheme. The scheme was kinetically of the first order. Here, the analysis is further developed for several first and second order schemes to gain a deeper insight into the thermodynamic consistency of rate equations and relationships between chemical thermodynamic and kinetics...
2018: Frontiers in Chemistry
Ren-You Gan, Kin-Weng Kong, Hua-Bin Li, Kao Wu, Ying-Ying Ge, Chak-Lun Chan, Xian-Ming Shi, Harold Corke
The red sword bean ( Canavalia gladiata ) is an underutilized edible bean cultivated in China. It was previously found to have the highest content of antioxidant polyphenols among 42 edible beans, mainly gallic acid, and gallotannins in its red bean coat, an apparently unique characteristic among edible beans. In this study, the main phenolic compounds in red sword bean coats were further separated by Sephadex LH-20 column chromatography, and identified by LC-MS/MS. Furthermore, the FRAP and ABTS antioxidant activities and antibacterial activity (diameter of inhibition zone, DIZ) of main gallotannin-rich fractions were tested...
2018: Frontiers in Chemistry
Xiaoyuan Ji, Houyu Wang, Bin Song, Binbin Chu, Yao He
Biochemical analysis in reliable, low-toxicity, and real-time manners are essentially important for exploring and unraveling biological events and related mechanisms. Silicon nanomaterial-based sensors and probes have potentiality to satisfy the above-mentioned requirements. Herein, we present an overview of the recent significant improvement in large-scale and facile synthesis of high-quality silicon nanomaterials and the research progress of biosensing and bioimaging analysis based on silicon nanomaterials...
2018: Frontiers in Chemistry
Chhabilal Regmi, Bhupendra Joshi, Schindra K Ray, Gobinda Gyawali, Ramesh P Pandey
Several photocatalytic nanoparticles are synthesized and studied for potential application for the degradation of organic and biological wastes. Although these materials degrade organic compounds by advance oxidation process, the exact mechanisms of microbial decontamination remains partially known. Understanding the real mechanisms of these materials for microbial cell death and growth inhibition helps to fabricate more efficient semiconductor photocatalyst for large-scale decontamination of environmental wastewater or industries and hospitals/biomedical labs generating highly pathogenic bacteria and toxic molecules containing liquid waste by designing a reactor...
2018: Frontiers in Chemistry
Ayda Nemati Vesali Azar, Seda Keskin
Efficient separation of acetylene (C2 H2 ) from CO2 and CH4 is important to meet the requirement of high-purity acetylene in various industrial applications. Metal organic frameworks (MOFs) are great candidates for adsorption-based C2 H2 /CO2 and C2 H2 /CH4 separations due to their unique properties such as wide range of pore sizes and tunable chemistries. Experimental studies on the limited number of MOFs revealed that MOFs offer remarkable C2 H2 /CO2 and C2 H2 /CH4 selectivities based on single-component adsorption data...
2018: Frontiers in Chemistry
Ol'ha O Brovarets', Kostiantyn S Tsiupa, Dmytro M Hovorun
For the first time novel high-energy conformers-A·T(wWC ) (5.36), A·T(wrWC ) (5.97), A·T(wH ) (5.78), and A·T(wrH ) (ΔG = 5.82 kcal·mol-1 ) (See Graphical Abstract ) were revealed for each of the four biologically important A·T DNA base pairs - Watson-Crick A·T(WC), reverse Watson-Crick A·T(rWC), Hoogsteen A·T(H) and reverse Hoogsteen A·T(rH) at the MP2/aug-cc-pVDZ//B3LYP/6-311++G(d,p) level of quantum-mechanical theory in the continuum with ε = 4 under normal conditions. Each of these conformers possesses substantially non-planar wobble (w) structure and is stabilized by the participation of the two anti-parallel N6H/N6H'…O4/O2 and N3H…N6 H-bonds, involving the pyramidalized amino group of the A DNA base as an acceptor and a donor of the H-bonding...
2018: Frontiers in Chemistry
Vincenzo Mirabello, Fernando Cortezon-Tamarit, Sofia I Pascu
Hypoxia has been identified as one of the hallmarks of tumor environments and a prognosis factor in many cancers. The development of ideal chemical probes for imaging and sensing of hypoxia remains elusive. Crucial characteristics would include a measurable response to subtle variations of pO2 in living systems and an ability to accumulate only in the areas of interest (e.g., targeting hypoxia tissues) whilst exhibiting kinetic stabilities in vitro and in vivo . A sensitive probe would comprise platforms for applications in imaging and therapy for non-communicable diseases (NCDs) relying on sensitive detection of pO2 ...
2018: Frontiers in Chemistry
Doris E Braun, Ulrich J Griesser
The observed moisture- and temperature dependent transformations of the dapsone (4,4'-diaminodiphenyl sulfone, DDS) 0. 33-hydrate were correlated to its structure and the number and strength of the water-DDS intermolecular interactions. A combination of characterization techniques was used, including thermal analysis (hot-stage microscopy, differential scanning calorimetry and thermogravimetric analysis), gravimetric moisture sorption/desorption studies and variable humidity powder X-ray diffraction, along with computational modeling (crystal structure prediction and pair-wise intermolecular energy calculations)...
2018: Frontiers in Chemistry
Chloé Roullier-Gall, Julie Signoret, Daniel Hemmler, Michael A Witting, Basem Kanawati, Bernhard Schäfer, Régis D Gougeon, Philippe Schmitt-Kopplin
Whisky can be described as a complex matrix integrating the chemical history from the fermented cereals, the wooden barrels, the specific distillery processes, aging, and environmental factors. In this study, using Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) and liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS), we analyzed 150 whisky samples from 49 different distilleries, 7 countries, and ranging from 1 day new make spirit to 43 years of maturation with different types of barrel...
2018: Frontiers in Chemistry
Mouna Lamaoui, Martin Jemo, Raju Datla, Faouzi Bekkaoui
Drought and heat are major abiotic stresses that reduce crop productivity and weaken global food security, especially given the current and growing impacts of climate change and increases in the occurrence and severity of both stress factors. Plants have developed dynamic responses at the morphological, physiological and biochemical levels allowing them to escape and/or adapt to unfavorable environmental conditions. Nevertheless, even the mildest heat and drought stress negatively affects crop yield. Further, several independent studies have shown that increased temperature and drought can reduce crop yields by as much as 50%...
2018: Frontiers in Chemistry
Camilla Calabrese, Assimo Maris, Luca Evangelisti, Anna Piras, Valentina Parravicini, Sonia Melandri
We describe an experimental and quantum chemical study for the accurate determination of the conformational space of small molecular systems governed by intramolecular non-covalent interactions. The model systems investigated belong to the biological relevant aminoalcohol's family, and include 2-amino-1-phenylethanol, 2-methylamino-1-phenylethanol, noradrenaline, adrenaline 2-aminoethanol, and N -methyl-2-aminoethanol. For the latter molecule, the rotational spectrum in the 6-18 and 59.6-74.4 GHz ranges was recorded in the isolated conditions of a free jet expansion...
2018: Frontiers in Chemistry
Qiang Lu, Zhen-Xi Zhang, Xin Wang, Hao-Qiang Guo, Min-Shu Cui, Yong-Ping Yang
A new technique was proposed to co-produce phenol and activated carbon (AC) from catalytic fast pyrolysis of biomass impregnated with K3 PO4 in a hydrogen atmosphere, followed by activation of the pyrolytic solid residues. Lab-scale catalytic fast pyrolysis experiments were performed to quantitatively determine the pyrolytic product distribution, as well as to investigate the effects of several factors on the phenol production, including pyrolysis atmosphere, catalyst type, biomass type, catalytic pyrolysis temperature, and catalyst impregnation content...
2018: Frontiers in Chemistry
Hongbin Yang, Lixia Sun, Weihua Li, Guixia Liu, Yun Tang
During drug development, safety is always the most important issue, including a variety of toxicities and adverse drug effects, which should be evaluated in preclinical and clinical trial phases. This review article at first simply introduced the computational methods used in prediction of chemical toxicity for drug design, including machine learning methods and structural alerts. Machine learning methods have been widely applied in qualitative classification and quantitative regression studies, while structural alerts can be regarded as a complementary tool for lead optimization...
2018: Frontiers in Chemistry
Aman C Kaushik, Sanjay Kumar, Dong Q Wei, Shakti Sahi
GPR142 (G protein receptor 142) is a novel orphan GPCR (G protein coupled receptor) belonging to "Class A" of GPCR family and expressed in β cells of pancreas. In this study, we reported the structure based virtual screening to identify the hit compounds which can be developed as leads for potential agonists. The results were validated through induced fit docking, pharmacophore modeling, and system biology approaches. Since, there is no solved crystal structure of GPR142, we attempted to predict the 3D structure followed by validation and then identification of active site using threading and ab initio methods...
2018: Frontiers in Chemistry
Mónica Bueno, Almudena Marrufo-Curtido, Vanesa Carrascón, Purificación Fernández-Zurbano, Ana Escudero, Vicente Ferreira
The main aim of the present work is to study the accumulation of acetaldehyde and Strecker aldehydes (isobutyraldehyde, 2-methylbutanal, isovaleraldehyde, methional, phenylacetaldehyde) during the oxidation of red wines, and to relate the patterns of accumulation to the wine chemical composition. For that, eight different wines, extensively chemically characterized, were subjected at 25°C to three different controlled O2 exposure conditions: low (10 mg L-1 ) and medium or high (the stoichiometrically required amount to oxidize all wine total SO2 plus 18 or 32 mg L-1 , respectively)...
2018: Frontiers in Chemistry
Sascha Siebenhaller, Julian Gentes, Alba Infantes, Claudia Muhle-Goll, Frank Kirschhöfer, Gerald Brenner-Weiß, Katrin Ochsenreither, Christoph Syldatk
Honey and agave syrup are high quality natural products and consist of more than 80% sugars. They are used as sweeteners, and are ingredients of cosmetics or medical ointments. Furthermore, both have low water content, are often liquid at room temperature and resemble some known sugar-based deep eutectic solvents (DES). Since it has been shown that it is possible to synthesize sugar esters in these DESs, in the current work honey or, as vegan alternative, agave syrup are used simultaneously as solvent and substrate for the enzymatic sugar ester production...
2018: Frontiers in Chemistry
Aleksey Firsov, Irina Tarasenko, Tatiana Mitiouchkina, Lyubov Shaloiko, Oleg Kozlov, Leonid Vinokurov, Ekaterina Rasskazova, Arkadii Murashev, Alexander Vainstein, Sergey Dolgov
The amino acid sequence of the extracellular domain of the virus-encoded M2 matrix protein (peptide M2e) is conserved among all subtypes of influenza A strains, enabling the development of a broad-range vaccine against them. We expressed M2e from avian influenza virus A/chicken/Kurgan/5/2005 (H5N1) in nuclear-transformed duckweed plants for further development of an avian influenza vaccine. The 30-amino acid N-terminal fragment of M2, including M2e (denoted M130), was selected for expression. The M2e DNA sequence fused in-frame to the 3' end of ricin toxin B chain (RTB) was cloned under control of the CaMV 35S promoter into pBI121...
2018: Frontiers in Chemistry
Jun He, Yaqing Wei, Lintong Hu, Huiqiao Li, Tianyou Zhai
GeP5 is a recently reported new anode material for lithium ion batteries (LIBs), it holds a large theoretical capacity about 2300 mAh g-1 , and a high rate capability due to its bi-active components and superior conductivity. However, it undergoes a large volume change during its electrochemical alloying and de-alloying with Li, a suitable binder is necessary to stable the electrode integrity for improving cycle performance. In this work, we tried to apply aqueous binders LiPAA and NaCMC to GeP5 anode, and compared the difference in electrochemical performance between them and traditional binder PVDF...
2018: Frontiers in Chemistry
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