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https://www.readbyqxmd.com/read/28549323/investigation-of-submicron-aerosol-characteristics-in-changzhou-china-composition-source-and-comparison-with-co-collected-pm2-5
#1
Zhaolian Ye, Qing Li, Jiashu Liu, Shipeng Luo, Quanfa Zhou, Chenglu Bi, Shuaishuai Ma, Yanfang Chen, Hui Chen, Ling Li, Xinlei Ge
Mass concentrations and chemical compositions of submicron particles (PM1) collected during July 2015 to April 2016 in Changzhou, a city in the Yangtze River Delta region, were systematically investigated for the first time. Specifically, an Aerodyne soot particle aerosol mass spectrometer (SP-AMS) was employed to characterize the water-soluble organic matter (WSOM). The average concentration of PM1 was 63.6 μg m(-3), occupying ∼60% of co-collected PM2.5 mass. Water soluble inorganic ions (WSIIs) was the most abundant component with secondary ions (SO4(2-), NO3(-) and NH4(+)) as the dominant species...
May 17, 2017: Chemosphere
https://www.readbyqxmd.com/read/28549256/assembly-and-inhibitory-activity-of-monovalent-mannosides-terminated-with-aromatic-methyl-esters-the-effect-of-naphthyl-groups
#2
Hussein Al-Mughaid, Raed M Al-Zoubi, Maha Khazaaleh, T Bruce Grindley
A series of monovalent α-D-mannoside ligands terminated with aromatic methyl esters have been synthesized in excellent yields using the Cu(I) catalyzed azide-alkyne 1,3-dipolar cycloaddition ("click chemistry"). These mannosides were designed to have a unique aglycone moiety (tail) that combines a triazole ring attached to aromatic methyl esters via a six carbon alkyl chain. The mannose unit of these ligands was linked at the ortho, meta, and para positions of substituted methyl benzoates and 1-, 3-, and 6-substituted methyl 2-napthaoates...
March 29, 2017: Carbohydrate Research
https://www.readbyqxmd.com/read/28548858/theoretical-study-of-acetic-acid-association-based-on-hydrogen-bonding-mechanism
#3
Minhua Zhang, Lihang Chen, Huaming Yang, Jing Ma
Combining molecular dynamics (MD) and quantum chemistry (QM) simulation, the association mechanism of acetic acid systems were examined. DFT method was proposed to compare the hydrogen-bonding energy of variable acetic acid dimers, and definitely provided the stable dimers configuration. Geometry parameters of dimers were also obtained by QM calculations, which were taken as the characteristic criteria for further MD analysis. Proportion of different acetic acid dimers in gas phase was obtained by Radial distribution function (RDF) analysis, and cyclic dimer with two O=c-Hoacid hydrogen bonds was demonstrated as the most stable structure...
May 26, 2017: Journal of Physical Chemistry. A
https://www.readbyqxmd.com/read/28548848/quantum-mechanical-study-of-the-reaction-mechanism-for-2%C3%AF-2%C3%AF-cycloaddition-of-fluorinated-methylene-groups
#4
Andrew R Motz, Andrew M Herring, Shubham Vyas, C Mark Maupin
Perfluorocyclobutyl polymers are thermally and chemically stable, may be produced without a catalyst via thermal 2π-2π cycloaddition, and can form block structures making them suitable for commercialization of specialty polymers. Thermal 2π-2π cycloaddition is a rare reaction that starts in the singlet state and proceeds through a triplet intermediate forming an energetically stable 4 membered ring in the singlet state. This reaction involves two changes in spin state and thus two spin-crossover transitions...
May 26, 2017: Journal of Organic Chemistry
https://www.readbyqxmd.com/read/28548843/zwitterionic-nanocarrier-surface-chemistry-improves-sirna-tumor-delivery-and-silencing-activity-relative-to-polyethylene-glycol
#5
Meredith A Jackson, Thomas A Werfel, Elizabeth J Curvino, Fang Yu, Taylor Elizabeth Kavanaugh, Samantha M Sarett, Mary D Dockery, Kameron V Kilchrist, Ayisha N Jackson, Todd D Giorgio, Craig L Duvall
Although siRNA-based nanomedicines hold promise for cancer treatment, conventional siRNA-polymer complex (polyplex) nanocarrier systems have poor pharmacokinetics following intravenous delivery, hindering tumor accumulation. Here, we determined the impact of surface chemistry on the in vivo pharmacokinetics and tumor delivery of siRNA polyplexes. A library of diblock polymers was synthesized, all containing the same pH-responsive, endosomolytic polyplex core-forming block but different corona blocks: 5 kDa (benchmark) and 20 kDa linear PEG, 10 kDa and 20 kDa brush-like poly(oligo ethylene glycol) (POEGMA), and 10 kDa and 20 kDa zwitterionic phosphorylcholine-based polymers (PMPC)...
May 26, 2017: ACS Nano
https://www.readbyqxmd.com/read/28548838/synthesis-of-defined-and-functionalized-glycans-of-lipoteichoic-acid-a-cell-surface-polysaccharide-from-clostridium-difficile
#6
Kang Yu, Ningning Bi, Chenghe Xiong, Shuihong Cai, Zhongzhu Long, Zhongwu Guo, Guofeng Gu
Two structurally defined, functionalized glycans of lipoteichoic acid (LTA, also known as PS-III) from C. difficile, which have one or two repeating units of LTA linked to the core trisaccharide, were efficiently synthesized via a convergent [2 + 3] or [2 + 2 + 3] strategy. The α-linkage of both N-acetylglucosamine residues in the repeating unit were constructed with glycosyl imidates of azidosugars as donors, while the phosphodiester bridges between the oligosaccharides were fashioned using H-phosphonate chemistry...
May 26, 2017: Organic Letters
https://www.readbyqxmd.com/read/28548830/stable-5-5%C3%A2-substituted-2-2%C3%A2-bipyrroles-building-blocks-for-macrocyclic-and-materials-chemistry
#7
Gonzalo Anguera, Brice Kauffmann, Jose Ignacio Borrell, Salvador Borros, David Sánchez-García
The preparation and characterization of a family of stable 2,2´-bipyrroles substituted at positions 5,5´with thienyl, phenyl, TMS-ethynyl, and vinyl groups is reported herein. The synthesis of these new bipyrroles comprises three steps: formation of the corresponding 5,5´-unsubstituted bipyrrole, bromination and Stille or Suzuki coupling. The best results in the coupling are obtained using the Stille reaction under microwave irradiation. The new compounds have been fully characterized by UV-vis absorption, fluorescence and IR spectroscopies and cyclic voltammetry...
May 26, 2017: Journal of Organic Chemistry
https://www.readbyqxmd.com/read/28548674/how-silver-segregation-stabilizes-1d-surface-gold-oxide-a-cluster-expansion-study-combined-with-ab-initio-md-simulations
#8
Sandra Hoppe, Yong Li, Lyudmila V Moskaleva, Stefan Müller
Gold has many unique properties, some of which continue to be uncovered, such as the rich chemistry of gold at the nanoscale. In this study, gold surprises us again by the unusual stability of one-dimensional gold oxide structures on the surface of gold, which enhances in the presence of silver impurities. We employ first-principles calculations to investigate the surface segregation of silver in the presence of atomic-oxygen adsorbates arranged in chains on the Au(321) surface. Such 1D oxide chains have previously been suggested as the most stable form of adsorbed oxygen on gold...
May 26, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28548499/polyoxovanadate-alkoxide-clusters-as-a-redox-reservoir-for-iron
#9
Feng Li, Stephanie H Carpenter, Robert F Higgins, Mark G Hitt, William W Brennessel, Maryline G Ferrier, Samantha K Cary, Juan S Lezama-Pacheco, Joshua T Wright, Benjamin W Stein, Matthew P Shores, Michael L Neidig, Stosh A Kozimor, Ellen M Matson
Inspired by the multielectron redox chemistry achieved using conventional organic-based redox-active ligands, we have characterized a series of iron-functionalized polyoxovanadate-alkoxide clusters in which the metal oxide scaffold functions as a three-dimensional, electron-deficient metalloligand. Four heterometallic clusters were prepared through sequential reduction, demonstrating that the metal oxide scaffold is capable of storing up to four electrons. These reduced products were characterized by cyclic voltammetry, IR, electronic absorption, and (1)H NMR spectroscopies...
May 26, 2017: Inorganic Chemistry
https://www.readbyqxmd.com/read/28548390/a-step-towards-removing-plasma-volume-variance-from-the-athlete-s-biological-passport-the-use-of-biomarkers-to-describe-vascular-volumes-from-a-simple-blood-test
#10
Louisa M Lobigs, Pierre-Edouard Sottas, Pitre C Bourdon, Zoran Nikolovski, Mohamed El-Gingo, Evdokia Varamenti, Peter Peeling, Brian Dawson, Yorck O Schumacher
The haematological module of the Athlete's Biological Passport (ABP) has significantly impacted the prevalence of blood manipulations in elite sports. However, the ABP relies on a number of concentration-based markers of erythropoiesis, such as haemoglobin concentration ([Hb]), which are influenced by shifts in plasma volume (PV). Fluctuations in PV contribute to the majority of biological variance associated with volumetric ABP markers. Our laboratory recently identified a panel of common chemistry markers (from a simple blood test) capable of describing ~67% of PV variance, presenting an applicable method to account for volume shifts within antidoping practices...
May 26, 2017: Drug Testing and Analysis
https://www.readbyqxmd.com/read/28548089/finding-multiple-reaction-pathways-via-global-optimization-of-action
#11
Juyong Lee, In-Ho Lee, InSuk Joung, Jooyoung Lee, Bernard R Brooks
Global searching for reaction pathways is a long-standing challenge in computational chemistry and biology. Most existing approaches perform only local searches due to computational complexity. Here we present a computational approach, Action-CSA, to find multiple diverse reaction pathways connecting fixed initial and final states through global optimization of the Onsager-Machlup action using the conformational space annealing (CSA) method. Action-CSA successfully overcomes large energy barriers via crossovers and mutations of pathways and finds all possible pathways of small systems without initial guesses on pathways...
May 26, 2017: Nature Communications
https://www.readbyqxmd.com/read/28547292/physiological-implications-of-ocean-acidification-for-marine-fish-emerging-patterns-and-new-insights
#12
REVIEW
Andrew J Esbaugh
Ocean acidification (OA) is an impending environmental stress facing all marine life, and as such has been a topic of intense research interest in recent years. Numerous detrimental effects have been documented in marine fish, ranging from reduced mortality to neurosensory impairment, and the prevailing opinions state that these effects are largely the downstream consequences of altered blood carbon dioxide chemistry caused by respiratory acid-base disturbances. While the respiratory acid-base disturbances are consistent responses to OA across tested fish species, it is becoming increasingly clear that there is wide variability in the degree of downstream impairments between species...
May 25, 2017: Journal of Comparative Physiology. B, Biochemical, Systemic, and Environmental Physiology
https://www.readbyqxmd.com/read/28546955/biofabrication-and-biomaterials-for-urinary-tract-reconstruction
#13
REVIEW
Moustafa M Elsawy, Achala de Mel
Reconstructive urologists are constantly facing diverse and complex pathologies that require structural and functional restoration of urinary organs. There is always a demand for a biocompatible material to repair or substitute the urinary tract instead of using patient's autologous tissues with its associated morbidity. Biomimetic approaches are tissue-engineering tactics aiming to tailor the material physical and biological properties to behave physiologically similar to the urinary system. This review highlights the different strategies to mimic urinary tissues including modifications in structure, surface chemistry, and cellular response of a range of biological and synthetic materials...
2017: Research and Reports in Urology
https://www.readbyqxmd.com/read/28546914/transmission-electron-microscopy-as-a-tool-for-the-characterization-of-soft-materials-application-and-interpretation
#14
REVIEW
Linda E Franken, Egbert J Boekema, Marc C A Stuart
Transmission electron microscopy (TEM) provides direct structural information on nano-structured materials and is popular as a characterization tool in soft matter and supramolecular chemistry. However, technical aspects of sample preparation are overlooked and erroneous image interpretations are regularly encountered in the literature. There are three most commonly used TEM methods as we derived from literature: drying, staining and cryo-TEM, which are explained here with respect to their application, limitations and interpretation...
May 2017: Advanced Science (Weinheim, Baden-Wurttemberg, Germany)
https://www.readbyqxmd.com/read/28546565/autocatalytic-time-dependent-evolution-of-metastable-two-component-supramolecular-assemblies-to-self-sorted-or-coassembled-state
#15
Tomoya Fukui, Masayuki Takeuchi, Kazunori Sugiyasu
Despite substantial effort devoted in the history of supramolecular chemistry, synthetic supramolecular systems still lag behind biomolecular systems in terms of complexity and functionality. This is because biomolecular systems function in a multicomponent molecular network under out-of-equilibrium conditions. Here we report two-component supramolecular assemblies that are metastable and thus show time-dependent evolution. We found that the systems undergo either self-sorting or coassembly in time depending on the combination of components...
May 25, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28546540/a-bioactive-chemical-markers-based-strategy-for-quality-assessment-of-botanical-drugs-xuesaitong-injection-as-a-case-study
#16
Zhenzhong Yang, Qing Shao, Zhiwei Ge, Ni Ai, Xiaoping Zhao, Xiaohui Fan
Current chemical markers based quality assessment methods largely fail to reflect intrinsic chemical complexity and multiple mechanisms of action of botanical drugs (BD). The development of novel quality markers is greatly needed. Here we propose bioactive chemical markers (BCM), defined as a group of chemo-markers that exhibit similar pharmacological activities comparable to the whole BD, which can therefore be used to effectively assess the quality of BD. As a proof-of-concept, a BCM-based strategy was developed and applied to Xuesaitong Injection (XST) for assessing the efficacy and consistency of different batches...
May 25, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28546518/safety-immunogenicity-and-cross-species-protection-of-a-plasmid-dna-encoding-plasmodium-falciparum-sera5-polypeptide-microbial-epitopes-and-chemokine-genes-in-mice-and-olive-baboons
#17
Nyamongo Onkoba, Ruth M Mumo, Horace Ochanda, Charles Omwandho, Hastings S Ozwara, Thomas G Egwang
Incorporation of biomolecular epitopes to malarial antigens should be explored in the development of strain-transcending malarial vaccines. The present study sought to determine safety, immunogenicity and cross-species efficacy ofPlasmodium falciparum serine repeat antigen 5 polypeptide co-expressed with epitopes of Bacille-Calmette Guerin (BCG), tetanus toxoid (TT) and a chemokine gene. Olive baboons and BALB/c mice were randomly assigned into vaccine and control groups. The vaccine group animals were primed and boosted twice with pIRES plasmids encoding the SERA5+ BCG+ TT alone, or with either CCL5 or CCL20 and the control group with pIRES plasmid vector backbone...
April 6, 2017: Journal of Biomedical Research
https://www.readbyqxmd.com/read/28546097/10-years-of-denosumab-treatment-in-postmenopausal-women-with-osteoporosis-results-from-the-phase-3-randomised-freedom-trial-and-open-label-extension
#18
Henry G Bone, Rachel B Wagman, Maria L Brandi, Jacques P Brown, Roland Chapurlat, Steven R Cummings, Edward Czerwiński, Astrid Fahrleitner-Pammer, David L Kendler, Kurt Lippuner, Jean-Yves Reginster, Christian Roux, Jorge Malouf, Michelle N Bradley, Nadia S Daizadeh, Andrea Wang, Paula Dakin, Nicola Pannacciulli, David W Dempster, Socrates Papapoulos
BACKGROUND: Long-term safety and efficacy of osteoporosis treatment are important because of the chronic nature of the disease. We aimed to assess the long-term safety and efficacy of denosumab, which is widely used for the treatment of postmenopausal women with osteoporosis. METHODS: In the multicentre, randomised, double-blind, placebo-controlled, phase 3 FREEDOM trial, postmenopausal women aged 60-90 years with osteoporosis were enrolled in 214 centres in North America, Europe, Latin America, and Australasia and were randomly assigned (1:1) to receive 60 mg subcutaneous denosumab or placebo every 6 months for 3 years...
May 22, 2017: Lancet Diabetes & Endocrinology
https://www.readbyqxmd.com/read/28545393/quantgenius-implementation-of-a-decision-support-system-for-qpcr-based-gene-quantification
#19
Špela Baebler, Miha Svalina, Marko Petek, Katja Stare, Ana Rotter, Maruša Pompe-Novak, Kristina Gruden
BACKGROUND: Quantitative molecular biology remains a challenge for researchers due to inconsistent approaches for control of errors in the final results. Due to several factors that can influence the final result, quantitative analysis and interpretation of qPCR data are still not trivial. Together with the development of high-throughput qPCR platforms, there is a need for a tool allowing for robust, reliable and fast nucleic acid quantification. RESULTS: We have developed "quantGenius" ( http://quantgenius...
May 25, 2017: BMC Bioinformatics
https://www.readbyqxmd.com/read/28545304/tracing-sources-of-nitrate-using-water-chemistry-land-use-and-nitrogen-isotopes-in-the-ganjiang-river-china
#20
Peng Wang, Junzheng Liu, Shuhua Qi, Shiqin Wang, Xiaoling Chen
In this work, we traced sources of nitrate in the Ganjiang River, a major tributary of Yangtze River, China, by analysing the water chemistry, nitrogen isotopes and land use. Water samples from 20 sites in the main stream and tributaries were collected in the dry and wet seasons. The [Formula: see text] ranged from 0.97 to 8.60 ‰, and was significantly higher in the wet season than in the dry season, and significantly higher in tributaries than in the main stream. In the dry season, [Formula: see text] concentrations and [Formula: see text] were significantly negatively correlated with forest and grassland areas, and positively correlated with paddy field and residential area...
May 25, 2017: Isotopes in Environmental and Health Studies
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