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Chemical reactions

Markus Köhler, Patrick Oßwald, Dominik Krueger, Ryan Whitside
This manuscript describes a high-temperature flow reactor experiment coupled to the powerful molecular beam mass spectrometry (MBMS) technique. This flexible tool offers a detailed observation of chemical gas-phase kinetics in reacting flows under well-controlled conditions. The vast range of operating conditions available in a laminar flow reactor enables access to extraordinary combustion applications that are typically not achievable by flame experiments. These include rich conditions at high temperatures relevant for gasification processes, the peroxy chemistry governing the low temperature oxidation regime or investigations of complex technical fuels...
February 19, 2018: Journal of Visualized Experiments: JoVE
Aurélie Fossey-Jouenne, Carine Vergne-Vaxelaire, Anne Zaparucha
Amino alcohols are versatile compounds with a wide range of applications. For instance, they have been used as chiral scaffolds in organic synthesis. Their synthesis by conventional organic chemistry often requires tedious multi-step synthesis processes, with difficult control of the stereochemical outcome. We present a protocol to enzymatically synthetize amino alcohols starting from the readily available L-lysine in 48 h. This protocol combines two chemical reactions that are very difficult to conduct by conventional organic synthesis...
February 16, 2018: Journal of Visualized Experiments: JoVE
Lisa N Chesner, Colin Campbell
The purpose of this method is to provide a flexible, rapid, and quantitative technique to examine the kinetics of DNA-protein crosslink (DPC) repair in mammalian cell lines. Rather than globally assaying removal of xenobiotic-induced or spontaneous chromosomal DPC removal, this assay examines the repair of a homogeneous, chemically defined lesion specifically introduced at one site within a plasmid DNA substrate. Importantly, this approach avoids the use of radioactive materials and is not dependent on expensive or highly-specialized technology...
March 5, 2018: Journal of Visualized Experiments: JoVE
Yangbo Wang, Bingxiao Yang, Kun Chen, Enlong Zhou, Qinghua Zhang, Lisha Yin, Xiaoji Xie, Lin Gu, Ling Huang
Scandium (Sc) sits at a unique position in the periodic table, i.e., the junction of the top of the rare earth column and the beginning of the transition metal row. Studies have shown that Sc-based nanomaterials are very sensitive to the surrounding chemical environment. A simple adjustment of the chemical reaction conditions such as temperature, surfactant molecules, and solvents (e.g., oleic acid (OA) or 1-octadecene (OD)) can easily lead to different products in terms of chemical composition and phase structure...
March 19, 2018: Dalton Transactions: An International Journal of Inorganic Chemistry
Lin Wang, Satyakam Dash, Chiam Yu Ng, Costas D Maranas
Metabolic pathways reflect an organism's chemical repertoire and hence their elucidation and design have been a primary goal in metabolic engineering. Various computational methods have been developed to design novel metabolic pathways while taking into account several prerequisites such as pathway stoichiometry, thermodynamics, host compatibility, and enzyme availability. The choice of the method is often determined by the nature of the metabolites of interest and preferred host organism, along with computational complexity and availability of software tools...
December 2017: Synthetic and Systems Biotechnology
Franziska Krieg, Stefan T Ochsenbein, Sergii Yakunin, Stephanie Ten Brinck, Philipp Aellen, Adrian Süess, Baptiste Clerc, Dominic Guggisberg, Olga Nazarenko, Yevhen Shynkarenko, Sudhir Kumar, Chih-Jen Shih, Ivan Infante, Maksym V Kovalenko
Colloidal lead halide perovskite nanocrystals (NCs) have recently emerged as versatile photonic sources. Their processing and optoelectronic applications are hampered by the loss of colloidal stability and structural integrity due to the facile desorption of surface capping molecules during isolation and purification. To address this issue, herein, we propose a new ligand capping strategy utilizing common and inexpensive long-chain zwitterionic molecules such as 3-( N , N -dimethyloctadecylammonio)propanesulfonate, resulting in much improved chemical durability...
March 9, 2018: ACS Energy Letters
Kamila Kočí, Ivana Troppová, Martin Reli, Lenka Matějová, Miroslava Edelmannová, Helena Drobná, Lada Dubnová, Anna Rokicińska, Piotr Kuśtrowski, Libor Čapek
Neodymium enriched TiO2 anatase-brookite powders were prepared by unconventional method via using pressurized hot fluids for TiO2 crystallization and purification. The photocatalysts were tested in the CH3 OH photocatalytic decomposition and they were characterized with respect to the textural (nitrogen adsorption), structural (XRD, XPS, and Raman spectroscopies), chemical (XRF), and optical (DR UV-Vis spectroscopy) and photoelectrochemical measurement. All prepared materials were nanocrystalline, had biphasic (anatase- brookite) structure and relatively large specific surface area (125 m2 ...
2018: Frontiers in Chemistry
Mariétou F Paye, Harrison B Rose, John M Robbins, Diana A Yunda, Seonggeon Cho, Andreas S Bommarius
Research involving α/β hydrolases, including α-amino acid ester hydrolase and cocaine esterase, has been limited by the lack of an online high throughput screening assay. The development of a high throughput screening assay capable of detecting α/β hydrolase activity toward specific substrates and/or chemical reactions (e.g., hydrolysis in lieu of amidase activity and/or synthesis instead of thioesterase activity) is of interest in a broad set of scientific questions and applications. Here we present a general framework for pH-based colorimetric assays, as well as the mathematical considerations necessary to estimate de novo the experimental response required to assign a 'hit' or a 'miss,' in the absence of experimental standard curves...
March 15, 2018: Analytical Biochemistry
Mariosimone Zoccali, Simone Cappello, Luigi Mondello
The present research is focused on the use of a triple quadrupole mass spectrometer (QqQ MS) coupled with flow modulated comprehensive two-dimensional gas chromatography (FM GC × GC) for a multilevel elucidation of biodegradation potentiality of natural marine microbial populations during a bioremediation (biostimulation) treatment. The crude oil used for the evaluation of the bioremediation process, namely Dansk Blend Pier E1, represents a very complex sample. Hence, in order to understand the metabolic activity of microbial populations during the bioremediation process, a GC × GC system was used...
March 12, 2018: Journal of Chromatography. A
Mona Jasmine R Ahonen, Dakota J Suchyta, Huanyu Zhu, Mark H Schoenfisch
Low and high molecular weight alginate biopolymers were chemically modified to store and release potentially therapeutic levels of nitric oxide (NO). Carbodiimide chemistry was first used to modify carboxylic acid functional groups with a series of small molecule alkyl amines. The resulting secondary amines were subsequently converted to N-diazeniumdiolate NO donors via reaction with NO gas under basic conditions. NO donor-modified alginates stored between 0.4-0.6 µmol NO•mg-1. In aqueous solution, the NO-release kinetics was diverse (0...
March 19, 2018: Biomacromolecules
Anand Mohan Verma, Harshal D Kawale, Kushagra Agrawal, Nanda Kishore
In the pyrolysis of Sphagnum moss species, p-isopropenylphenol (p-IPP) is a major product which has been considered in this density functional theory based computational study for its conversion to various products such as benzene, phenol, 4-propenylphenol, indan-5-ol, 4-propylcyclohexanone, 4-cyclopropylphenol, etc. In order to achieve these products, eight different reaction schemes are performed using B3LYP/6-311 + g (d,p) level of theory. Further, thermodynamic properties such as reaction free energies and reaction enthalpies associated with these eight reaction schemes are developed in the temperature range of 298-898 K...
March 9, 2018: Journal of Molecular Graphics & Modelling
Nelly Flores, Farbod Sharif, Nael Yasri, Enric Brillas, Ignasi Sirés, Edward P L Roberts
This work compares the ability of physical and chemical treatments, namely adsorption and electrochemical advanced oxidation processes, to remove tyrosol from aqueous medium. Adsorption on graphene nanoplatelets (GNPs) performed much better than that with a graphite intercalation compound. Adsorption isotherms were found to follow the Freundlich model (R2  = 0.96), which is characteristic of a chemisorption process. Successful electrochemical regeneration enables 5 successive adsorption/regeneration cycles before corrosion of GNPs occurs...
March 7, 2018: Chemosphere
Pin Hou, Zhe Yan, Fred S Cannon, Ye Yue, Timothy Byrne, Cesar Nieto-Delgado
In order to obtain a high adsorption capacity for perchlorate, the epoxide-forming quaternary ammonium (EQA) compounds were chemically bonded onto granular activated carbon (GAC) surface by cationic reaction. The optimum preparation condition of the cationic GAC was achieved while applying softwood-based Gran C as the parent GAC, dosing EQA first at a pH of 12, preparation time of 48 h, preparation temperature of 50 °C, and mole ratio of EQA/oxygen groups of 2.5. The most favorable cationic GAC that had the QUAB360 pre-anchored exhibited the highest perchlorate adsorption capacity of 24...
March 6, 2018: Chemosphere
P Bouschon, A-C Bursztejn, J Waton, F Brault, J-L Schmutz
BACKGROUND: Hair bleaching is increasingly being carried out in hairdressing salons. The products used are a mixture of hydrogen peroxide and persulfates, both active chemical agents. Scalp burns secondary to hair bleaching are a traumatic adverse effect rarely discussed in publications that continue to be little known among healthcare professionals. PATIENTS AND METHODS: We report the case of a 15-year-old girl with a plaque of scarring alopecia on the vertex. This lesion resulted from a deep burn following a hair-bleaching procedure...
March 14, 2018: Annales de Dermatologie et de Vénéréologie
Jie-Lin Wang, Qian Chen, Bei-Bei Du, Lu Cao, Hong Lin, Zhong-Yong Fan, Jian Dong
The composite polylactide PLLA/β-TCP scaffolds were fabricated by solution casting and were coated with gelatin/hydroxyapatite (Gel/HAp) to improve the biological properties of the composite scaffolds. The Gel/HAp mixture was prepared using an in situ reaction, and a grafting-coating method was used to increase the efficiency of coating the PLLA/β-TCP matrix with Gel/HAp. First, free amino groups were introduced by 1,6-hexanediamine to aminolyze the PLLA/β-TCP matrix surface. Second, glutaraldehyde was coupled to Gel/HAp as a crosslinking agent...
June 1, 2018: Materials Science & Engineering. C, Materials for Biological Applications
Ahmed Ma'mun, Mohamed K Abd El-Rahman, Mohamed Abd El-Kawy
In recent years, the whole field of ion-selective electrodes(ISEs) in pharmaceutical sciences has expanded far beyond its original roots. The diverse range of opportunities offered by ISEs was broadly used in a number of pharmaceutical applications, with topics presented ranging from bioanalysis of drugs and metabolites, to protein binding studies, green analytical chemistry, impurity profiling, and drug dissolution in biorelevant media. Inspired from these advances and with the aim of extending the functional capabilities of ISEs, the primary focus of the present paper is the utilization of ISE as a tool in personalized medicine...
February 7, 2018: Journal of Pharmaceutical and Biomedical Analysis
Lixin He, Qingbin Zhang, Pengfei Lan, Wei Cao, Xiaosong Zhu, Chunyang Zhai, Feng Wang, Wenjing Shi, Muzi Li, Xue-Bin Bian, Peixiang Lu, André D Bandrauk
Molecules constituted by different isotopes are different in vibrational modes, making it possible to elucidate the mechanism of a chemical reaction via the kinetic isotope effect. However, the real-time observation of the vibrational motion of isotopic nuclei in molecules is still challenging due to its ultrashort time scale. Here we demonstrate a method to monitor the nuclear vibration of isotopic molecules with the frequency modulation of high-order harmonic generation (HHG) during the laser-molecule interaction...
March 16, 2018: Nature Communications
Kazuhiro Yamaguchi, Takao Tsuji, Kazutetsu Aoshiba, Hiroyuki Nakamura
In Europe and America, the newly-developed, simultaneous measurement of diffusing capacity for CO (DLCO ) and NO (DLNO ) has replaced the classic DLCO measurement for detecting the pathophysiological abnormalities in the acinar regions. However, simultaneous measurement of DLCO and DLNO is currently not used by Japanese physicians. To encourage the use of DLNO in Japan, the authors reviewed aspects of simultaneously-estimated DLCO and DLNO from previously published manuscripts. The simultaneous DLCO -DLNO technique identifies the alveolocapillary membrane-related diffusing capacity (membrane component, DM ) and the blood volume in pulmonary microcirculation (VC ); VC is the principal factor constituting the blood component of diffusing capacity (DB ,DB =θ·VC where θ is the specific gas conductance for CO or NO in the blood)...
March 2018: Respiratory Investigation
Weizheng Wang, Feng Chen, Yaqi Wang, Lina Wang, Haiyan Fu, Fuping Zheng, Lance Beecher
Reducing sugars have strong reactivity with 1-phenyl-3-methyl-5-pyrazolone (PMP) to form the sugar-PMP derivatives, which can be more accurately analyzed by HPLC-UV at 248 nm. Glucose and glucosamine reacted with the PMP based on the response surface methodology within a range of temperature between 60 °C and 80 °C, and time between 60 and 180 min. The optimal conditions for the glucose-PMP and glucosamine-PMP reactions were obtained at 71 °C for 129 min, and 73 °C for 96 min, respectively...
July 15, 2018: Food Chemistry
Jin Wang, Wei Cao, Ming Ma, Quanshui Zheng
The diffusion of molecules and clusters under nanoscale confinement or absorbed on surfaces is the key controlling factor in dynamical processes such as transport, chemical reaction, or filtration. Enhancing diffusion could benefit these processes by increasing their transport efficiency. Using a nonlinear Langevin equation with an extensive number of simulations, we find a large enhancement in diffusion through surface oscillation. For helium confined in a narrow carbon nanotube, the diffusion enhancement is estimated to be over three orders of magnitude...
February 2018: Physical Review. E
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