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https://www.readbyqxmd.com/read/29353313/general-solution-of-the-chemical-master-equation-and-modality-of-marginal-distributions-for-hierarchic-first-order-reaction-networks
#1
Matthias Reis, Justus A Kromer, Edda Klipp
Multimodality is a phenomenon which complicates the analysis of statistical data based exclusively on mean and variance. Here, we present criteria for multimodality in hierarchic first-order reaction networks, consisting of catalytic and splitting reactions. Those networks are characterized by independent and dependent subnetworks. First, we prove the general solvability of the Chemical Master Equation (CME) for this type of reaction network and thereby extend the class of solvable CME's. Our general solution is analytical in the sense that it allows for a detailed analysis of its statistical properties...
January 20, 2018: Journal of Mathematical Biology
https://www.readbyqxmd.com/read/29353197/bioanalytical-assessment-of-adaptive-stress-responses-in-drinking-water-a-predictive-tool-to-differentiate-between-micropollutants-and-disinfection-by-products
#2
Armelle Hebert, Cedric Feliers, Caroline Lecarpentier, Peta A Neale, Rita Schlichting, Sylvie Thibert, Beate I Escher
Drinking water can contain low levels of micropollutants, as well as disinfection by-products (DBPs) that form from the reaction of disinfectants with organic and inorganic matter in water. Due to the complex mixture of trace chemicals in drinking water, targeted chemical analysis alone is not sufficient for monitoring. The current study aimed to apply in vitro bioassays indicative of adaptive stress responses to monitor the toxicological profiles and the formation of DBPs in three drinking water distribution systems in France...
January 3, 2018: Water Research
https://www.readbyqxmd.com/read/29352930/an-efficient-approach-to-prepare-sulfated-polysaccharide-and-evaluation-of-anti-tumor-activities-in-vitro
#3
Junlong Wang, Aijuan Bao, Xinhua Meng, Hongyun Guo, Yongdong Zhang, Yali Zhao, Weibao Kong, Junyu Liang, Jian Yao, Ji Zhang
Use of microwave radiation is one of the most potential techniques in polysaccharide derivatives synthesis due to its advantages such as higher yields, milder reaction conditions and shorter reaction times. This study was aimed at producing sulfated polysaccharides by microwave irradiation using polar reagents and solvent. Six sulfated Artemisia sphaerocephala polysaccharide derivatives (SPAS) were obtained by using chlorosulfuric acid/pyridine method in the reaction duration range of 15-300 min at a fixed microwave power of 100W...
March 15, 2018: Carbohydrate Polymers
https://www.readbyqxmd.com/read/29352925/influence-of-hydrothermal-treatment-on-the-structural-modification-of-spent-grain-specific-carbohydrates-and-the-formation-of-degradation-products-using-model-compounds
#4
J Steiner, K Franke, M Kießling, S Fischer, S Töpfl, V Heinz, T Becker
Brewer's spent grain (BSG) constitutes various valuable carbohydrates that may contribute to a healthy diet. These components may be obtained from BSG via hydrothermal treatment (HT), a procedure for dissolving water-inextricable carbohydrates. The objective of this study was to investigate HT as an environmentally friendly technology for extracting high-molecular-weight fiber with proven beneficial effects on human health. Cellulose, β-glucan, and arabinoxylan (AX) served as model substances and were subjected to auto-hydrolysis at different temperatures and reaction times...
March 15, 2018: Carbohydrate Polymers
https://www.readbyqxmd.com/read/29352905/glucose-sensitive-polyelectrolyte-microcapsules-based-on-alginate-chitosan-pair
#5
Sabrina Belbekhouche, Saddam Charaabi, Luc Picton, Didier Le Cerf, Benjamin Carbonnier
Novel chemical stimulus-responsive multilayer assemblies have been elaborated through the layer-by-layer deposition of oppositely charged polysaccharides on either flat or spherical surfaces. Concentration-dependent glucose responsiveness was obtained through chemical modification of alginate, selected as polyanion, with phenylboronic acid moieties. QCM measurements showed that the alginate derivate still self-assembles though electrostatically-driven interactions with chitosan at pH 4, and that the polysaccharides multilayer assemblies, as obtained after crosslinking, exhibit improved stability versus pH (in the range 4-9) as well as swelling ability in the presence of glucose-containing solution...
March 15, 2018: Carbohydrate Polymers
https://www.readbyqxmd.com/read/29352877/valorization-of-peanut-shells-manufacture-of-bioactive-oligosaccharides
#6
Xiana Rico, Beatriz Gullón, José Luis Alonso, Juan Carlos Parajó, Remedios Yáñez
Peanut shells were subjected to non-isothermal aqueous treatments to cause the partial breakdown of hemicelluloses into soluble oligosaccharides and lignin-derived compounds with high antioxidant activity. The effects of temperature on the chemical composition of the substrate and soluble reaction products were assessed. Under selected conditions (210°C, severity=4.09), the overall amount of poly- and oligo- saccharides present in the liquid phase reached 9.8g/L. This solution was refined by consecutive stages of discontinuous diafiltration, yielding a refined product containing about 72...
March 1, 2018: Carbohydrate Polymers
https://www.readbyqxmd.com/read/29352787/communication-exact-analytical-derivatives-for-the-domain-based-local-pair-natural-orbital-mp2-method-dlpno-mp2
#7
Peter Pinski, Frank Neese
Electron correlation methods based on pair natural orbitals (PNOs) have gained an increasing degree of interest in recent years, as they permit energy calculations to be performed on systems containing up to many hundred atoms, while maintaining chemical accuracy for reaction energies. We present an approach for taking exact analytical first derivatives of the energy contributions in the simplest method of the family of Domain-based Local Pair Natural Orbital (DLPNO) methods, closed-shell DLPNO-MP2. The Lagrangian function contains constraints to account for the relaxation of PNOs...
January 21, 2018: Journal of Chemical Physics
https://www.readbyqxmd.com/read/29352388/cutaneous-granulomatosis-a-comprehensive-review
#8
REVIEW
Benedetta Terziroli Beretta-Piccoli, Carlo Mainetti, Marie-Astrid Peeters, Emmanuel Laffitte
Cutaneous granulomatosis is a heterogeneous group of diseases, characterized by a skin inflammatory reaction triggered by a wide variety of stimuli, including infections, foreign bodies, malignancy, metabolites, and chemicals. From a pathogenic point of view, they are divided into non-infectious and infectious granulomas. Pathophysiological mechanisms are still poorly understood. Non-infectious granulomatous skin diseases include granuloma annulare, necrobiosis lipoidica, rheumatic nodules, foreign body granulomas, cutaneous sarcoidosis, and interstitial granulomatous dermatitis...
January 19, 2018: Clinical Reviews in Allergy & Immunology
https://www.readbyqxmd.com/read/29352116/the-chemical-fluctuation-theorem-governing-gene-expression
#9
Seong Jun Park, Sanggeun Song, Gil-Suk Yang, Philip M Kim, Sangwoon Yoon, Ji-Hyun Kim, Jaeyoung Sung
Gene expression is a complex stochastic process composed of numerous enzymatic reactions with rates coupled to hidden cell-state variables. Despite advances in single-cell technologies, the lack of a theory accurately describing the gene expression process has restricted a robust, quantitative understanding of gene expression variability among cells. Here we present the Chemical Fluctuation Theorem (CFT), providing an accurate relationship between the environment-coupled chemical dynamics of gene expression and gene expression variability...
January 19, 2018: Nature Communications
https://www.readbyqxmd.com/read/29352089/cryptic-production-of-trans-3-hydroxyproline-in-echinocandin-b-biosynthesis
#10
Johanna Mattay, Stefanie Houwaart, Wolfgang Hüttel
Echinocandins are antifungal nonribosomal hexapeptides produced by fungi. Two of the amino acids are hydroxy-l-prolines: trans-4-hydroxy-l-proline and, in most echinocandin structures, (trans-2,3)-3-hydroxy-(trans-2,4)-4-methyl-l-proline. In the case of echinocandin biosynthesis by Glarea lozoyensis, both amino acids are found in pneumocandin A0, while in pneumocandin B0 the latter residue is substituted by trans-3- hydroxy-l-proline (3-Hyp). We have recently reported that all three amino acids are generated by the 2-oxoglutarate-dependent proline hydroxylase GloF...
January 19, 2018: Applied and Environmental Microbiology
https://www.readbyqxmd.com/read/29351884/crucial-role-of-chelatable-iron-in-silver-nanoparticles-induced-dna-damage-and-cytotoxicity
#11
Agnieszka Grzelak, Maria Wojewódzka, Sylwia Meczynska-Wielgosz, Mariusz Zuberek, Dominika Wojciechowska, Marcin Kruszewski
Damage to mitochondria and subsequent ROS leakage is a commonly accepted mechanism of nanoparticle toxicity. However, malfunction of mitochondria results in generation of superoxide anion radical (O2•-), which due to the relatively low chemical reactivity is rather unlikely to cause harmful effects triggered by nanoparticles. We show that treatment of HepG2 cells with silver nanoparticles (AgNPs) resulted in generation of H2O2 instead of O2•-, as measured by ROS specific mitochondrial probes. Moreover, addition of a selective iron chelator diminished AgNPs toxicity...
January 9, 2018: Redox Biology
https://www.readbyqxmd.com/read/29351373/a-facile-space-confined-solid-phase-sulfurization-strategy-for-growth-of-high-quality-ultrathin-molybdenum-disulfide-single-crystals
#12
Dawei Li, Zhiyong Xiao, Sai Mu, Fei Wang, Ying Liu, Jingfeng Song, Xi Huang, Lijia Jiang, Jun Xiao, Lei Liu, Stephen Ducharme, Bai Cui, Xia Hong, Lan Jiang, Jean-Francois Silvain, Yongfeng Lu
Single-crystal transition metal dichalcogenides (TMDs) and TMD-based hetero-junctions have recently attracted significant research and industrial interest owing to their intriguing optical and electrical properties. However, the lack of a simple, low-cost, environmentally friendly, synthetic method and a poor understanding of the growth mechanism post a huge challenge to implementing TMDs in practical applications. In this work, we developed a novel approach for direct formation of high-quality, monolayer and few-layer MoS2 single crystal domains via a single-step rapid thermal processing of a sandwiched reactor with sulfur and molybdenum (Mo) film in a confined reaction space...
January 19, 2018: Nano Letters
https://www.readbyqxmd.com/read/29350910/highly-asymmetric-phase-behaviors-of-polyhedral-oligomeric-silsesquioxanes-based-multi-headed-giant-surfactants
#13
Mingjun Huang, Kan Yue, Jiahao Huang, Chang Liu, Zhe Zhou, Jing Wang, Kan Wu, Wenpeng Shan, An-Chang Shi, Stephen Z D Cheng
This work reports the molecular design, synthesis, and systematic study on the bulk self-assembly behaviors of three series of polyhedral oligomeric silsesquioxanes (POSS)-based multi-headed giant surfactants XDPOSS-PSn (X = 2, 3 and 4), which are composed of two, three or four hydrophilic hydroxyl-group functionalized DPOSS cages attached via one junction point to a hydrophobic polystyrene (PS) chain. These series of hybrid polymeric amphiphiles with precisely defined chemical structure and controllable molecular architecture are synthesized by the sequential usage of "click" reactions...
January 19, 2018: ACS Nano
https://www.readbyqxmd.com/read/29350526/folding-graphene-film-yields-high-areal-energy-storage-in-lithium-ion-batteries
#14
Bin Wang, Jaegeon Ryu, Sungho Choi, Gyujin Song, Dongki Hong, Chihyun Hwang, Xiong Chen, Bo Wang, Wei Li, Hyun-Kon Song, Soojin Park, Rodney S Ruoff
We show that a high energy density can be achieved in a practical manner with freestanding electrodes without using conductive carbon, binders, and current collectors. We made and used a folded graphene composite electrode designed for a high areal capacity anode. The traditional thick graphene composite electrode, such as made by filtering graphene oxide to create a thin film and reducing it such as through chemical or thermal methods, has sluggish reaction kinetics. Instead, we have made and tested a thin composite film electrode that was folded several times using a water-assisted method; it provides a continuous electron transport path in the fold regions and introduces more channels between the folded layers, which significantly enhances the electron/ion transport kinetics...
January 19, 2018: ACS Nano
https://www.readbyqxmd.com/read/29350521/facile-and-highly-effective-synthesis-of-controllable-lattice-sulfur-doped-graphene-quantum-dots-via-hydrothermal-treatment-of-durian
#15
Gang Wang, Qinglei Guo, Da Chen, Zhiduo Liu, Xiaohu Zheng, Anli Xu, Siwei Yang, Guqiao Ding
Recently, the biomass "bottom-up" approach for the synthesis of graphene quantum dots have attracted broad interest because of the outstanding features, including low-cost, rapid and environmentally friendly nature. However, the low crystalline quality of products, substitutional doping with heteroatoms in lattice and ambiguous reaction mechanism strongly challenge the further development of this technique. Herein, we proposed a facile and effective strategy to prepare controllable sulfur (S) doping in graphene quantum dots, occurring in a lattice substitution manner, by hydrothermal treatment of durian with platinum catalyst...
January 19, 2018: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/29350030/correction-to-tunneling-control-of-chemical-reactions-the-third-reactivity-paradigm
#16
Peter R Schreiner
No abstract text is available yet for this article.
January 19, 2018: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/29349857/a-diazido-mannose-analog-as-a-chemoenzymatic-synthon-for-synthesizing-di-n-acetyllegionaminic-acid-containing-glycosides
#17
Abhishek Santra, An Xiao, Hai Yu, Wanqing Li, Yanhong Li, Linh Ngo, John B McArthur, Xi Chen
A novel strategy is developed to expand the scope of chemoenzymatic synthetic products by designing a chemoenzymatic synthon. The synthon is enzymatically converted to carbohydrate analogs which are readily derivatized chemically to produce desired targets. The strategy is demonstrated for synthesizing glycosides containing 7,9-di-N-acetyllegionaminic acid (Leg5,7Ac2), a bacterial nonulosonic acid (NulO) analog of sialic acid. A versatile library of a2-3/6-linked Leg5,7Ac2- glycosides is built using chemically synthesized 2,4-diazido-2,4,6-trideoxy mannose as a chemoenzymatic synthon for highly efficient one-pot multienzyme (OPME) sialylation followed by a downstream chemical conversion of the azido group to an acetamido group...
January 19, 2018: Angewandte Chemie
https://www.readbyqxmd.com/read/29349298/direct-measurements-of-doco-isomers-in-the-kinetics-of-od-co
#18
Thinh Q Bui, Bryce J Bjork, P Bryan Changala, Thanh L Nguyen, John F Stanton, Mitchio Okumura, Jun Ye
Quantitative and mechanistically detailed kinetics of the reaction of hydroxyl radical (OH) with carbon monoxide (CO) have been a longstanding goal of contemporary chemical kinetics. This fundamental prototype reaction plays an important role in atmospheric and combustion chemistry, motivating studies for accurate determination of the reaction rate coefficient and its pressure and temperature dependence at thermal reaction conditions. This intricate dependence can be traced directly to details of the underlying dynamics (formation, isomerization, and dissociation) involving the reactive intermediates cis- and trans-HOCO, which can only be observed transiently...
January 2018: Science Advances
https://www.readbyqxmd.com/read/29349297/organic-matter-in-extraterrestrial-water-bearing-salt-crystals
#19
Queenie H S Chan, Michael E Zolensky, Yoko Kebukawa, Marc Fries, Motoo Ito, Andrew Steele, Zia Rahman, Aiko Nakato, A L David Kilcoyne, Hiroki Suga, Yoshio Takahashi, Yasuo Takeichi, Kazuhiko Mase
Direct evidence of complex prebiotic chemistry from a water-rich world in the outer solar system is provided by the 4.5-billion-year-old halite crystals hosted in the Zag and Monahans (1998) meteorites. This study offers the first comprehensive organic analysis of the soluble and insoluble organic compounds found in the millimeter-sized halite crystals containing brine inclusions and sheds light on the nature and activity of aqueous fluids on a primitive parent body. Associated with these trapped brines are organic compounds exhibiting wide chemical variations representing organic precursors, intermediates, and reaction products that make up life's precursor molecules such as amino acids...
January 2018: Science Advances
https://www.readbyqxmd.com/read/29348803/synthesis-of-a-chloroalkene-dipeptide-isostere-containing-peptidomimetic-and-its-biological-application
#20
Takuya Kobayakawa, Yudai Matsuzaki, Kentaro Hozumi, Wataru Nomura, Motoyoshi Nomizu, Hirokazu Tamamura
The first rapid and efficient chemical synthesis of a cyclic Arg-Gly-Asp (RGD) peptide containing a chloroalkene dipeptide isostere (CADI) is reported. By a developed synthetic method, an N-tert-butylsulfonyl protected CADI was obtained utilizing diastereoselective allylic alkylation as a key reaction. This CADI was also transformed into an N-Fmoc protected CADI in a few steps. The CADI was used in Fmoc-based solid-phase peptide synthesis. The first synthesis of a CADI-containing cyclic RGD peptide was successful, and the synthesized CADI-containing peptidomimetic was found to be a more potent inhibitor against integrin-mediated cell attachment than the parent cyclic peptide...
January 11, 2018: ACS Medicinal Chemistry Letters
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