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Chemical reactions

Giovanni Salassa, Annelies Sels, Fabrizio Mancin, Thomas Burgi
Thiolate monolayer, protecting gold nanocluster, is the principal responsible of their chemical behavior and their interaction with the environment. Understanding the parameters that influence the sta-bility and reactivity of the monolayer will enable its precise and controlled functionalization. Here we present a protocol for the investigation of the monolayer reactivity in Au25(SR)18 based on MALDI mass spectrometry and NMR spectroscopy. Thiol ex-change reaction between cluster and thiol molecules has been inves-tigated showing how this reaction is affected by the thiol affinity for Au25...
November 22, 2017: ACS Nano
Michael Renzler, Lorenz Kranabetter, Erik Barwa, Lukas Grubwieser, Paul Scheier, Andrew M Ellis
Low energy electron attachment to mixed (H2)x/(O2)y clusters and their deuterated analogs has been investigated for the first time. These experiments were carried out using liquid helium nanodroplets to form the clusters, and the effect of the added electron was then monitored via mass spectrometry. There are some important differences between electron attachment to the pure clusters and to the mixed clusters. A particularly notable feature is the formation of HO2(-) and H2O(-) ions from an electron-induced chemical reaction between the two dopants...
November 21, 2017: Journal of Chemical Physics
Yayi Cheng, Jianfeng Huang, Hui Qi, Liyun Cao, Xiaomin Luo, Jiayin Li, Zhanwei Xu, Jun Yang
The Sn-C bonding content between the SnO2 and CNTs interface was controlled by the hydrothermal method and subsequent heat treatment. Electrochemical analysis found that the SnO2@CNTs with high Sn-C bonding content exhibited much higher capacity contribution from alloying and conversion reaction compared with the low content of Sn-C bonding even after 200 cycles. The high Sn-C bonding content enabled the SnO2 nanoparticles to stabilize on the CNTs surface, realizing an in situ pulverization process of SnO2...
November 22, 2017: Nanoscale
Sarabjeet Kaur, Purshotam Sharma, Stacey D Wetmore
The RNA world hypothesis assumes that RNA was the first informational polymer that originated from prebiotic chemical soup. However, since the reaction of d-ribose with canonical nucleobases (A, C, G and U) fails to yield ribonucleosides (rNs) in substantial amounts, the spontaneous origin of rNs and the subsequent synthesis of RNA remains an unsolved mystery. To this end, it has been suggested that RNA may have evolved from primitive genetic material (preRNA) composed of simpler prebiotic heterocycles that spontaneously form glycosidic bonds with ribose...
November 22, 2017: Physical Chemistry Chemical Physics: PCCP
Iñigo Bretos, Ricardo Jiménez, Jesús Ricote, M Lourdes Calzada
Over the last few years the efforts devoted to the research on low-temperature processing of metal oxide thin films have increased notably. This has enabled the direct integration of metal oxide layers (amorphous semiconductors) on low-melting-point polymeric substrates for flexible electronic systems, which adds to the economic and environmental benefits of the use of these processes with reduced energy consumption. More challenging is the preparation of crystalline complex oxide films at temperatures compatible with their direct integration in flexible devices...
November 22, 2017: Chemical Society Reviews
Deborah E Crawford, Clodagh K Miskimmin, John Cahir, S L James
Chemical manufacturing typically requires more than one step, involving multiple batch processes, which makes synthesis at scale laborious and wasteful. Herein, we demonstrate that several reactions can be telescoped into a single continuous process and/or be carried out as a continuous multi-component reaction (MCR), by twin screw extrusion (TSE), in the complete absence of solvent.
November 22, 2017: Chemical Communications: Chem Comm
Roosevelt D S Bezerra, Régis C Leal, Mateus S da Silva, Alan I S Morais, Thiago H C Marques, Josy A Osajima, Andréia B Meneguin, Hernane da S Barud, Edson C da Silva Filho
Cellulose derivatives have been widely used as adsorbents for the removal of micropollutants such as drugs, dyes, and metals, due to their abundance, low cost and non-contaminating nature. In this context, several studies have been performed searching for new adsorbents (cellulose derivatives) efficient at contaminant removal from aqueous solutions. Thus, a new adsorbent was synthesized by chemical modification of cellulose with ethylenediamine in the absence of solvent and applied to the adsorption of amitriptyline (AMI) in aqueous solution...
November 22, 2017: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
Maria Arkel, Patrizia Garbati, Annalisa Salis, Gianluca Damonte, Nara Liessi, Enrico Adriano, Umberto Benatti, Maurizio Balestrino, Enrico Millo
Background Adenosine triphosphate (ATP) is the energy currency of the body; it takes part in various and indispensable metabolic processes for the maintenance of cell homeostasis, degrading to its hydrolysis product, adenosine diphosphate (ADP). Efficient ways to restore ATP are therefore necessary in the cells. When the cell lacks energy due to ischemic conditions or high ATP demand, phosphocreatine gives its phosphate group to ADP that converts to ATP, in a reaction catalyzed by the enzyme creatine kinase...
November 20, 2017: Medicinal Chemistry
Jing Liang, Jin Zhang, Zhenzhu Li, Hao Hong, Jinhuan Wang, Zhihong Zhang, Xu Zhou, Ruixi Qiao, Jiyu Xu, Peng Gao, Zhirong Liu, Zhongfan Liu, Zhipei Sun, Sheng Meng, Kaihui Liu, Dapeng Yu
Strain serves as a powerful freedom to effectively, reversibly, and continuously engineer the physical and chemical properties of two-dimensional (2D) materials, such as bandgap, phase diagram, and reaction activity. Although there is a high demand for full characterization of the strain vector at local points, it is still very challenging to measure the local strain amplitude and its direction. Here, we report a novel approach to monitor the local strain vector in 2D molybdenum diselenide (MoSe2) by polarization-dependent optical second-harmonic generation (SHG)...
November 22, 2017: Nano Letters
Thomas Wurm, Ben W H Turnbull, Brett R Ambler, Michael J Krische
Benzocyclobutenones 1a-1g undergo cycloreversion at 150 °C in m-xylene solvent to form transient α-oxo-ortho-quinodimethanes or "ortho-quinoid ketene methides", which engage in intermolecular [4+2] cycloadditions with isatins 2a-2f to form 2-oxindole spirolactones 3a-3l. This process tolerates an array of different functional groups and substitution patterns, and is applicable to unprotected isatins 2b-2f bearing free NH-functionalities. The superior performance of isatins compared to other carbonyl based dienophiles was demonstrated and rationalized with the aid of quantum chemical calculations...
November 22, 2017: Journal of Organic Chemistry
Oleg Borodin, Xiaoming Ren, Jenel Vatamanu, Arthur von Wald Cresce, Jaroslaw Knap, Kang Xu
Electroactive interfaces distinguish electrochemistry from chemistry and enable electrochemical energy devices like batteries, fuel cells, and electric double layer capacitors. In batteries, electrolytes should be either thermodynamically stable at the electrode interfaces or kinetically stable by forming an electronically insulating but ionically conducting interphase. In addition to a traditional optimization of electrolytes by adding cosolvents and sacrificial additives to preferentially reduce or oxidize at the electrode surfaces, knowledge of the local electrolyte composition and structure within the double layer as a function of voltage constitutes the basis of manipulating an interphase and expanding the operating windows of electrochemical devices...
November 22, 2017: Accounts of Chemical Research
Md Rajibul Akanda, Huangxian Ju
Highly sensitive analytical methods for the detection of proteins are still an urgent demand in early medical diagnosis and discovery of biomarkers with ultralow abundance. Here an integrated electrochemical-chemical-enzymatic redox cycling is designed for significant enhancement of electrochemical enzymatic signal in biorecognition. This strategy efficiently utilizes the high specificity of outer-sphere to inner-sphere redox reaction to mediate the enzymatic redox cycling with the nonenzymatic redox cycling...
November 22, 2017: Analytical Chemistry
Kyungsu Kang, Lei Peng, Yu-Jin Jung, Joo Yeon Kim, Eun Ha Lee, Hee Ju Lee, Sang Min Kim, Sang Hyun Sung, Cheol-Ho Pan, Yongsoo Choi
OBJECTIVES: To develop a high-throughput screening system to measure the conversion of testosterone to dihydrotestosterone (DHT) in cultured human prostate cancer cells using turbulent flow chromatography liquid chromatography-triple quadrupole mass spectrometry (TFC-LC-TQMS). RESULTS: After optimizing the cell reaction system, this method demonstrated a screening capability of 103 samples, including 78 single compounds and 25 extracts, in less than 12 h without manual sample preparation...
November 21, 2017: Biotechnology Letters
Chandu Singh, Sripathy K V, Jeevan Kumar S P, Bhojaraja Naik K, Govind Pal, Udaya Bhaskar K, Ramesh K V, Somasundaram G
BACKGROUND: Rice aleurone layer develops different colours with various chemical tests that may help to develop some rapid tests for identification/grouping of rice varieties. Understanding the colour inheritance pattern could enable to develop chemical clues that may help for genetic purity analysis along with grow-out-test. RESULTS: In this study, inheritance pattern of aleurone layer colour was studied in parents, F1 and F2 progenies derived from the crosses IR 36 × Acc...
November 21, 2017: Rice
Mateus R Barone, Alan M Jones
A chemical oxidant-free and mediator-free, direct electro-oxidation of both benzylic alcohols and benzylic esters are reported. The scope of the reaction is explored as a function of both steric and electronic effects. Expansion of the scope to non-benzylic and heteroaryl substrates is investigated. Functionalisation of esters and alcohols selectively to the aldehyde oxidation level using a traceless electron approach is reported.
November 22, 2017: Organic & Biomolecular Chemistry
Estefânia V R Campos, Jhones L Oliveira, Leonardo F Fraceto
Chitosan, a polyaminosaccharide obtained by alkaline deacetylation of chitin, possesses useful properties including biodegradability, biocompatibility, low toxicity, and good miscibility with other polymers. It is extensively used in many applications in biology, medicine, agriculture, environmental protection, and the food and pharmaceutical industries. The amino and hydroxyl groups present in the chitosan backbone provide positions for modifications that are influenced by factors such as the molecular weight, viscosity, and type of chitosan, as well as the reaction conditions...
2017: Frontiers in Chemistry
Gemma-Louise Davies, Joseph Govan, Renata Tekoriute, Raquel Serrano-García, Hugo Nolan, David Farrell, Ory Hajatpour, Yurii K Gun'ko
On-demand initiation of chemical reactions is becoming increasingly popular in many areas. The use of a magnetic field to trigger reactions is an intriguing concept, with vast potential in both research and industrial settings, though it remains a challenge as yet unsolved. Here we report the first example of on-demand magnetic activation of a polymerisation process using an anaerobic adhesive formulation as an example of this new approach toward triggering polymerisation reactions using an external magnetic field...
November 1, 2017: Chemical Science
Robert Naumann, Christoph Kerzig, Martin Goez
The ruthenium-tris-bipyridyl dication as catalyst combined with the ascorbate dianion as bioavailable sacrificial donor provides the first regenerative source of hydrated electrons for chemical syntheses on millimolar scales. This electron generator is operated simply by illumination with a frequency-doubled Nd:YAG laser (532 nm) running at its normal repetition rate. Much more detailed information than by product studies alone was obtained by photokinetical characterization from submicroseconds (time-resolved laser flash photolysis) up to one hour (preparative photolysis)...
November 1, 2017: Chemical Science
Jinping Lai, Shihui Li, Xuechen Shi, James Coyne, Nan Zhao, Fengping Dong, Yingwei Mao, Yong Wang
A variety of hydrogels have been synthesized for controlling the release of signaling molecules in applications such as drug delivery and regenerative medicine. However, it remains challenging to synthesize hydrogels with the ability to control the release of signaling molecules sequentially or periodically under physiological conditions as living cells do in response to the variation of metabolism. The purpose of this work was to study a novel biomimetic hydrogel system with the ability of recapitulating the procedure of cellular signal transduction and controlling the sequential release of signaling molecules under physiological conditions...
November 1, 2017: Chemical Science
David Velázquez-Palmero, Carmen Romero-Segura, Rosa García-Rodríguez, María L Hernández, Fabián E Vaistij, Ian A Graham, Ana G Pérez, José M Martínez-Rivas
Phenolic composition of virgin olive oil is determined by the enzymatic and/or chemical reactions that take place during olive fruit processing. Of these enzymes, β-glucosidase activity plays a relevant role in the transformation of the phenolic glycosides present in the olive fruit, generating different secoiridoid derivatives. The main goal of the present study was to characterize olive fruit β-glucosidase genes and enzymes responsible for the phenolic composition of virgin olive oil. To achieve that, we have isolated an olive β-glucosidase gene from cultivar Picual (OepGLU), expressed in Nicotiana benthamiana leaves and purified its corresponding recombinant enzyme...
2017: Frontiers in Plant Science
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