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Frontiers in Chemistry

Alison Tasker, Frank Sainsbury, Simon Puttick
The encapsulation of small molecule drugs in nanomaterials has become an increasingly popular approach to the delivery of therapeutics. The use of emulsions as templates for the synthesis of drug impregnated nanomaterials is an exciting area of research, and a great deal of progress has been made in understanding the interfacial chemistry that is critical to controlling the physicochemical properties of both the encapsulated material and the templated material. For example, control of the interfacial tension between an oil and aqueous phase is a fundamental concern when designing drug delivery vehicles that are stabilized by particulate surfactants at the fluid interface...
2018: Frontiers in Chemistry
Feng Jiang, Sijie Li, Peng Ge, Honghu Tang, Sultan A Khoso, Chenyang Zhang, Yue Yang, Hongshuai Hou, Yuehua Hu, Wei Sun, Xiaobo Ji
Restricted by the dissatisfied capacity of traditional materials, lithium-ion batteries (LIBs) still suffer from the low energy-density. The pursuing of natural electrode resources with high lithium-storage capability has triggered a plenty of activities. Through the hydro-refining process of raw molybdenite ore, containing crushing-grinding, flotation, exfoliation, and gradient centrifugation, 2D molybdenum disulfide (MoS2 ) with high purity is massively obtained. The effective tailoring process further induce various sizes (5, 2, 1 and 90 nm) of sheets, accompanying with the increasing of active sites and defects...
2018: Frontiers in Chemistry
Taber S Maskrey, Madeline C Frischling, Mikhaila L Rice, Peter Wipf
A new multi-component condensation was discovered during the reaction of a urea, β-keto ester, and formaldehyde. In the presence of catalytic indium bromide, a Biginelli dihydropyrimidinone intermediate was further converted to a five-component condensation product through a formal hetero Diels-Alder reaction. The product structure was confirmed by NMR and NOE analysis, and the proposed stepwise mechanism was supported by the reaction of the Biginelli intermediate with ethyl 2-methylene-3-oxobutanoate.
2018: Frontiers in Chemistry
Sugiarto, Keisuke Kawamoto, Yoshihito Hayashi
An isolation of a vanadium(V) oxide cluster mimicking V2 O5 layered structure was achieved formulated as [{Co(tacn)}4 V4 O12 (OH)4 ]4+ ( 1 ) (tacn = 1,4,7-triazacyclononane). From the 51 V NMR spectra of the reaction mixtures, we optimized the reaction condition in terms of a molar ratio of VO4 3- and [Co(tacn)(H2 O)3 ]3+ as well as a pH value. Cluster 1 is stable in a wide range of pH values from 1.5 to 8.0, and the presence of multiple hydrogen bondings in the structure is a unique feature. In the X-ray analysis of cluster 1 , the V⋯ V distances are classified into two groups of relatively shorter distances (2...
2018: Frontiers in Chemistry
Fabio Licciardello, Elena Arena, Valeria Rizzo, Biagio Fallico
The study aimed at screening the levels of ascorbic acid, hydroxycinnamic acids (HCAs) and total anthocyanins in commercial beverages containing blood orange juice (BOJ), estimating the contribution of these products to the intake of health-promoting compounds and at discussing the actual value of the products on a price/bioactive level basis. Results demonstrate that the reference to BOJ in many beverages is misleading, as inferred from the very low bioactive levels observed. These beverages, in label should refer as "water-based" instead of "fruit-based beverage...
2018: Frontiers in Chemistry
Thomas Quanten, Tessa De Mayaer, Pavletta Shestakova, Tatjana N Parac-Vogt
In this paper we investigate the effect of three different types of surfactants, on the hydrolysis of Cytochrome c (Cyt c), a predominantly α helical protein containing a heme group, promoted by [Ce(α PW11 O 39 )2]10- (CeK) and [Zr(α PW11 O 39 )2]10- (ZrK) polyoxometalates. In the presence of SDS, Zw3 12, or CHAPS surfactants, which are commonly used for solubilizing hydrophobic proteins, the specificity of CeK or ZrK toward hydrolysis of Cyt c does not change. However, the hydrolysis rate of Cyt c by CeK was increased in the presence of SDS, but decreased in the presence of CHAPS, and was nearly inhibited in the presence of Zw3 12...
2018: Frontiers in Chemistry
Qingyan Zhang, Qu Zhou, Zhaorui Lu, Zhijie Wei, Lingna Xu, Yingang Gui
Tin oxide SnO2 -based gas sensors have been widely used for detecting typical fault characteristic gases extracted from power transformer oil, namely, H2 , CO, CO2 , CH4 , C2 H2 , C2 H4 , and C2 H6 , due to the remarkable advantages of high sensitivity, fast response, long-term stability, and so on. Herein, we present an overview of the recent significant improvement in fabrication and application of high performance SnO2 -based sensors for detecting these fault characteristic gases. Promising materials for the sensitive and selective detection of each kind of fault characteristic gas have been identified...
2018: Frontiers in Chemistry
Roumiana Tsenkova, Jelena Munćan, Bernhard Pollner, Zoltan Kovacs
Aquaphotomics is a novel scientific discipline involving the study of water and aqueous systems. Using light-water interaction, it aims to extract information about the structure of water, composed of many different water molecular conformations using their absorbance bands. In aquaphotomics analysis, specific water structures (presented as water absorbance patterns) are related to their resulting functions in the aqueous systems studied, thereby building an aquaphotome-a database of water absorbance bands and patterns correlating specific water structures to their specific functions...
2018: Frontiers in Chemistry
Lei Xie, Jingyi Wang, Jun Huang, Xin Cui, Xiaogang Wang, Qingxia Liu, Hao Zhang, Qi Liu, Hongbo Zeng
The anisotropic surface characteristics and interaction mechanisms of molybdenite (MoS2 ) basal and edge planes have attracted much research interest in many interfacial processes such as froth flotation. In this work, the adsorption of a polymer depressant [i.e., carboxymethyl cellulose (CMC)] on both MoS2 basal and edge surfaces as well as their interaction mechanisms with air bubbles have been characterized by atomic force microscope (AFM) imaging and quantitative force measurements. AFM imaging showed that the polymer coverage on the basal plane increased with elevating polymer concentration, with the formation of a compact polymer layer at 100 ppm CMC; however, the polymer adsorption was much weaker on the edge plane...
2018: Frontiers in Chemistry
Isabella Chiarotto, Leonardo Mattiello, Fabiana Pandolfi, Daniele Rocco, Marta Feroci
Ionic liquids (ILs) are considered in the majority of cases green solvents, due to their virtually null vapor pressure and to the easiness in recycling them. In particular, imidazolium ILs are widely used in many fields of Chemistry, as solvents or precursors of N-heterocyclic carbenes (NHCs). The latter are easily obtained by deprotonation of the C2-H, usually using strong bases or cathodic reduction. Nevertheless, it is known that weaker bases (e.g., triethylamine) are able to promote C2-H/D exchange. From this perspective, the possibility of deprotonating C2-H group of an imidazolium cation by means of a basic counter-ion was seriously considered and led to the synthesis of imidazolium ILs spontaneously containing NHCs...
2018: Frontiers in Chemistry
Felipe M Llancalahuen, Juan A Fuentes, Alexander Carreño, César Zúñiga, Dayán Páez-Hernández, Manuel Gacitúa, Rubén Polanco, Marcelo D Preite, Ramiro Arratia-Pérez, Carolina Otero
In this study, we explored new properties of the bioinspired pyridine benzimidazole compound B2 (2,4-di-tert-butyl-6-(3H-imidazo[4,5-c]pyridine-2-yl)phenol) regarding its potential use as a differential biomarker. For that, we performed 1D 1 HNMR (TOCSY), UV-Vis absorption spectra in different organic solvents, voltammetry profile (including a scan-rate study), and TD-DFT calculations that including NBO analyses, to provide valuable information about B2 structure and luminescence. In our study, we found that the B2 structure is highly stable, where the presence of an intramolecular hydrogen bond (IHB) seems to have a crucial role in the stability of luminescence, and its emission can be assigned as fluorescence...
2018: Frontiers in Chemistry
Yalong Cong, Yuchen Li, Kun Jin, Susu Zhong, John Z H Zhang, Hao Li, Lili Duan
In this study, the differences of binding patterns between two type HIV (HIV-1 and HIV-2) protease and two inhibitors (darunavir and amprenavir) are analyzed and compared using the newly developed interaction entropy (IE) method for the entropy change calculation combined with the polarized force field. The functional role of protonation states in the two HIV-2 complexes is investigated and our study finds that the protonated OD1 atom of Asp25' in B chain is the optimal choice. Those calculated binding free energies obtained from the polarized force field combined with IE method are significantly consistent with the experimental observed...
2018: Frontiers in Chemistry
Sara Chumillas, Beatriz Maestro, Juan M Feliu, Víctor Climent
In recent years, enzymatic fuel cells have experienced a great development promoted by the availability of novel biological techniques that allow the access to a large number of enzymatic catalysts. One of the most important aspects in this area is the development of biocatalysts for the oxygen reduction reaction (ORR). Laccases from the group of enzymes called blue multi-cooper oxidases have received considerable attention because of their ability to catalyze the electrochemical oxygen reduction reaction to water when immobilized on metallic or carbonaceous electrode materials...
2018: Frontiers in Chemistry
Luca Palazzolo, Chiara Parravicini, Tommaso Laurenzi, Uliano Guerrini, Cesare Indiveri, Elisabetta Gianazza, Ivano Eberini
The molecular mechanism of transport mediated by LAT1, a sodium-independent antiporter of large neutral amino acids, was investigated through in silico procedures, specifically making reference to two transported substrates, tyrosine (Tyr) and leucine methyl ester (LME), and to 3,5-diiodo-L-tyrosine (DIT), a well-known LAT1 inhibitor. Two models of the transporter were built by comparative modeling, with LAT1 either in an outward-facing (OF) or in an inward-facing (IF) conformation, based, respectively, on the crystal structure of AdiC and of GadC...
2018: Frontiers in Chemistry
Fernando D Vila, John W Spencer, Joshua J Kas, John J Rehr, Frank Bridges
Extended x-ray absorption fine structure (EXAFS) is well-suited for investigations of structure and disorder of complex materials. Recently, experimental measurements and analysis of EXAFS have been carried out to elucidate the mechanisms responsible for the negative thermal expansion (NTE) in zirconium tungstate (ZrW2 O8 ). In contrast to previous work suggesting that transverse O-displacements are largely responsible, the EXAFS analysis suggested that correlated rotations and translations of octahedra and tetrahedra within the structure are a major source...
2018: Frontiers in Chemistry
Siyu Liu, Ayesha Murtaza, Yan Liu, Wanfeng Hu, Xiaoyun Xu, Siyi Pan
Polyphenol oxidase (PPO) in plants plays an important role in browning reactions and may affect the quality of sweet melon products. In this study, a browning-related protein (BRP) with PPO activity was partially purified from oriental sweet melon ( Cucumis melo var. makuwa Makino) by salt precipitation and column chromatography. The BRP possessed a high degree of identity with several chitinase proteins, particularly defense-related proteins, by MS identification. Pyrogallol was determined as the most appropriate substrate for BRP ( K m = 0...
2018: Frontiers in Chemistry
Yong Liu, Huijie Wei, Chao Wang, Fei Wang, Haichao Wang, Wanhong Zhang, Xianfu Wang, Chenglin Yan, Bok H Kim, Fengzhang Ren
Due to the cost-effectiveness of sodium source, sodium-ion batteries (SIBs) have attracted considerable attention. However, SIBs still have some challenges in competing with lithium-ion batteries for practical applications. Particularly, the high rate capability and cycling stability are posing big problems for SIBs. Here, nitrogen-doped carbon-coated WS2 nanosheets (WS2 /NC) were successfully synthesized by a high-temperature solution method, followed by carbonization of polypyrrole. When used as anode electrodes for SIBs, WS2 /NC composite exhibited high-rate capacity at 386 and 238...
2018: Frontiers in Chemistry
Sheshshayee M Sreeman, Preethi Vijayaraghavareddy, Rohini Sreevathsa, Sowmya Rajendrareddy, Smitharani Arakesh, Pooja Bharti, Prathibha Dharmappa, Raju Soolanayakanahally
[This corrects the article DOI: 10.3389/fchem.2018.00092.].
2018: Frontiers in Chemistry
J Paul Attfield
Negative thermal expansion (NTE) upon heating is an unusual property but is observed in many materials over varying ranges of temperature. A brief review of mechanisms for NTE and prominent materials will be presented here. Broadly there are two basic mechanisms for intrinsic NTE within a homogenous solid; structural and electronic. Structural NTE is driven by transverse vibrational motion in insulating framework-type materials e.g., ZrW2 O8 and ScF3 . Electronic NTE results from thermal changes in electronic structure or magnetism and is often associated with phase transitions...
2018: Frontiers in Chemistry
Simelys Hernández, Chiara Gionco, Thomas Husak, Micaela Castellino, José A Muñoz-Tabares, Kristine R Tolod, Elio Giamello, Maria C Paganini, Nunzio Russo
In the present work, the activity of Ce and Er-doped ZrO2 nanopowders for sun-driven photocatalytic water oxidation has been investigated. ZrO2 powders with tunable amounts of tetragonal, monoclinic and cubic polymorphs have been synthesized by introducing Ce and Er (from 0.5 to 10 mol % on an oxide basis) through hydrothermal method. The aim of this work is to investigate the role of rare earth (RE) ions rich of electrons (Er3+ ) and with entirely empty levels (Ce4+ ) in the ZrO2 matrix for the sun-driven photocatalytic water oxidation reaction...
2018: Frontiers in Chemistry
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