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https://www.readbyqxmd.com/read/28102930/modulation-of-the-thermodynamic-signatures-of-an-rna-thermometer-by-osmolytes-and-salts
#1
Mimi Gao, Loana Arns, Roland Winter
Folding of ribonucleic acids (RNAs) is driven by several factors, such as base pairing and stacking, chain entropy, and ion-mediated electrostatics, which have been studied in great detail. However, the power of background molecules in the cellular milieu is often neglected. Herein, we study the effect of common osmolytes on the folding equilibrium of a hairpin-structured RNA and, using pressure perturbation, provide novel thermodynamic and volumetric insights into the modulation mechanism. The presence of TMAO causes an increased thermal stability and a more positive volume change for the helix-to-coil transition, whereas urea destabilizes the hairpin and leads to an increased expansibility of the unfolded state...
January 19, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28102388/crystal-structure-of-ba2-la0-727ba0-182m0-091-mo6-m-nb-sb-bi-symmetry-nuance-identified-in-photoluminescence-and-ir-spectroscopy-studies
#2
Rohan Phatak, Santosh K Gupta, Priya Maheshwari, Amitabh Das, Sanjay K Sali
A one-third lanthanum deficiency was created in Ba2LaM(5+)O6 compounds (LaM compounds) to form Ba2La2/3M(5+)O5.5 compounds (La2/3M compounds) for M = Nb, Sb, and Bi. The compounds were prepared by a gel-combustion method using citric acid as a fuel. All the compounds were characterized by powder X-ray diffraction (XRD). The XRD analysis showed that the space group of the La2/3M compounds remains the same for the Bi and Sb samples when compared to the reported LaM compounds, except for the Nb sample. La2/3Nb and La2/3Sb adopt a rhombohedral structure with the space group R3[combining macron], whereas La2/3Bi adopts a monoclinic structure with the space group I2/m...
January 19, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
https://www.readbyqxmd.com/read/28101849/mechanistic-study-of-the-gas-phase-in-source-hofmann-elimination-of-doubly-quaternized-cinchona-alkaloid-based-phase-transfer-catalysts-by-electrospray-ionization-tandem-mass-spectrometry
#3
Rong-Sheng Yang, Huaming Sheng, Katrina W Lexa, Edward C Sherer, Li-Kang Zhang, Bangping Xiang, Roy Helmy, Bing Mao
An unusual in-source fragmentation pattern observed for 14 doubly quaternized cinchona alkaloid-based phase-transfer catalysts (PTC) was studied using (+)-ESI high resolution mass spectrometry. Loss of the substituted benzyl cation (R1 or R2) was found to be the major product ion [M(2+) - R1(+) or R2(+)](+) in MS spectra of all PTC compounds. A Hofmann elimination product ion [M - H](+) was also observed. Only a small amount of the doubly charged M(2+) ions were observed in the MS spectra, likely due to strong Columbic repulsion between the two quaternary ammonium cations in the gas phase...
January 18, 2017: Journal of the American Society for Mass Spectrometry
https://www.readbyqxmd.com/read/28100417/long-range-and-regional-transported-size-resolved-atmospheric-aerosols-during-summertime-in-urban-shanghai
#4
Xiaoxiao Ding, Lingdong Kong, Chengtian Du, Assiya Zhanzakova, Lin Wang, Hongbo Fu, Jianmin Chen, Xin Yang, Tiantao Cheng
In this study, the concentrations of water soluble ions (WSI), organic carbon (OC), and elemental carbon (EC) of size-resolved (0.056-18μm) atmospheric aerosols were measured in July and August 2015 in Shanghai, China. Backward trajectory model and potential source contribution function (PSCF) model were used to identify the potential source distributions of size-resolved particles and PM1.8-associated atmospheric inorganic and carbonaceous aerosols. The results showed that the average mass concentrations of PM0...
January 15, 2017: Science of the Total Environment
https://www.readbyqxmd.com/read/28099950/nano-particles-assembled-porous-core-shell-znmn2o4-microspheres-with-superb-performance-for-lithium-batteries
#5
Tong Zhang, Huijuan Yue, Hailong Qiu, Wei Yingjin, Chunzhong Wang, Gang Chen, Zhang Dong
Porous ZnMn2O4 microspheres were prepared via a facile co-precipitation method followed by calcination at various temperatures and evaluated as anode materials for Lithium ion batteries. The sample prepared at 600��C outperformed the other samples in terms of electrochemical performance with high reversible capacity, high-rate capability, and excellent cycling performance. The capacity of the sample remained as high as 999 mAh g-1 at a current rate of 100 mA g-1 after 50 cycles ��� one of the best ever reported for ZnMn2O4-based materials...
January 18, 2017: Nanotechnology
https://www.readbyqxmd.com/read/28099805/the-importance-of-cannizzaro-type-reactions-during-electrocatalytic-reduction-of-carbon-dioxide
#6
Yuvraj Y Birdja, Marc T M Koper
A seemingly catalytic inactive electrode as boron doped diamond is found to be active for CO2 and CO reduction to formaldehyde and even methane. At very cathodic potentials formic acid and methanol are formed as well. However, these products are the result of base-catalyzed Cannizzaro-type disproportionation reactions. A local alkaline environment near the electrode surface, caused by the hydrogen evolution reaction, initiates aldehyde disproportionation promoted by hydroxide ions, which leads to the formation of the corresponding carboxylic acid and alcohol...
January 18, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28099802/stabilization-of-giant-fullerenes-c2-41-c90-d3-85-c92-c1-132-c94-c2-157-c96-and-c1-175-c98-by-encapsulation-of-a-large-la2c2-cluster-the-importance-of-cluster-cage-matching
#7
Shasha Zhao, Pei Zhao, Wenting Cai, Lipiao Bao, Muqing Chen, Yunpeng Xie, Xiang Zhao, Xing Lu
Successful isolation and unambiguous crystallographic assignment of a series of higher carbide cluster metallofullerenes present new insights into the molecular structures and cluster-cage interactions of endohedral metallofullerenes (EMFe). These new species are identified as: La2C2@C2(41)-C90, La2C2@D3(85)-C92, La2C2@C1(132)-C94, La2C2@C2(157)-C96 and La2C2@C1(175)-C98, respectively. This is the first report for these new cage structures except D3(85)-C92. Our experimental and theoretical results demonstrate that La2C92-106 are more inclined to exist stably in the carbide form La2C2@C90-104 rather than as the dimetallofullerenes La2@C92-106 which are rationalized by considering a synergistic effect of inserting a C2-unit into the cage which ensures strong metal-cage interactions by partially neutralizing the charges from the metal ions and by fulfilling the coordination requirement of the La3+ ions as much as possible, finally unraveling the mystery of the formation mechanism of giant fullerenes...
January 18, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28099570/variation-of-the-interphase-heterochromatin-in-artemia-crustacea-anostraca-of-the-americas-is-related-to-changes-in-nuclear-size-and-ionic-composition-of-hipersaline-habitats
#8
M Parraguez, G Gajardo
The populations of Artemia (or brine shrimp) from the Americas exhibit a wide variation in the amount of interphase heterochromatin. There is interest in understanding how this variation affects different parameters, from the cellular to the organismal levels. This should help to clarify the ability of this organism to tolerate brine habitats regularly subject to strong abiotic changes. In this study, we assessed the amount of interphase heterochromatin per nucleus based on chromocenter number (N-CHR) and relative area of chromocenter (R-CHR) in two species of Artemia, A...
January 12, 2017: Brazilian Journal of Biology, Revista Brasleira de Biologia
https://www.readbyqxmd.com/read/28099171/an-approach-to-estimate-spatial-distribution-of-analyte-within-cells-using-spectrally-resolved-fluorescence-microscopy
#9
Dharmendar Kumar Sharma, Mir Irfanullah, Santanu Kumar Basu, Sheri Madhu, Suman De, Sameer Jadhav, Mangalampalli Ravikanth, Arindam Chowdhury
While fluorescence microscopy has become an essential tool amongst chemists and biologists for the detection of various analyte within cellular environments, non-uniform spatial distribution of sensors within cells often restricts extraction of reliable information on relative abundance of analytes in different subcellular regions. As an alternative to existing sensing methodologies such as ratiometric or FRET imaging, where relative proportion of analyte with respect to the sensor can be obtained within cells, we propose a methodology using spectrally-resolved fluorescence microscopy, via which both the relative abundance of sensor as well as their relative proportion with respect to the analyte can be simultaneously extracted for local subcellular regions...
January 18, 2017: Methods and Applications in Fluorescence
https://www.readbyqxmd.com/read/28099170/exploring-the-ability-of-the-nalidixate-to-sensitize-visible-and-near-infrared-emitting-lanthanide-iii-cations
#10
Svetlana V Eliseeva, Valerii S Liasotkyi, Iurii P Golovach, Pavel G Doga, Valery P Antonovich, Stéphane Petoud, Svetlana B Meshkova
Recently, a strong interest has been directed towards near-infrared (NIR) emitting lanthanide(III) compounds as they do possess complementary advantages in respect to organic molecules and semi-conductor nanocrystals, especially in the fields of biological analysis and imaging. To benefit from their emission, a key requirement to fulfill is the sensitization of lanthanide(III) cations with an appropriate chromophore. This condition is especially challenging to address for the lanthanide(III) cations emitting in the NIR...
January 18, 2017: Methods and Applications in Fluorescence
https://www.readbyqxmd.com/read/28099025/optical-line-width-broadening-mechanisms-at-the-10-khz-level-in-eu-3-y2o3-nanoparticles
#11
John G Bartholomew, Karmel de Oliveira Lima, Alban Ferrier, Philippe Goldner
We identify the physical mechanisms responsible for the optical homogeneous broadening in Eu(3+):Y2O3 nanoparticles to determine whether rare-earth crystals can be miniaturized to volumes less than λ(3) while preserving their appeal for quantum technology hardware. By studying how the homogeneous line width depends on temperature, applied magnetic field, and measurement time scale, the dominant broadening interactions for various temperature ranges above 3 K were characterized. Below 3 K the homogeneous line width is dominated by an interaction not observed in bulk crystal studies...
January 18, 2017: Nano Letters
https://www.readbyqxmd.com/read/28098445/circular-and-chainlike-copper-ii-lanthanide-iii-complexes-generated-by-assembly-reactions-of-racemic-and-chiral-copper-ii-cross-linking-ligand-complexes-with-ln-iii-no3-3%C3%A2-6h2o-ln-iii-gd-iii-tb-iii-dy-iii
#12
Takahiro Ueno, Takeshi Fujinami, Naohide Matsumoto, Masaki Furusawa, Ryo Irie, Nazzareno Re, Takuya Kanetomo, Takayuki Ishida, Yukinari Sunatsuki
The 1:1 assembly reaction of the racemic form of the cross-linking ligand complex Na[Cu(II)L(dpen(1R2R/1S2S))] with Ln(III)(NO3)3·6H2O gave the centrosymmetric circular (Cu(II)Ln(III))2 complex [Cu(II)L(dpen(1R2R/1S2S))Ln(III)(NO3)2]2 (1Ln: Ln = Gd, Tb, Dy), while the reaction of the enantiopure form Na[Cu(II)L(dpen(1R2R))] with Ln(III)(NO3)3·6H2O gave the chiral chainlike (Cu(II)Ln(III))1∞ complex [Cu(II)L(dpen(1R2R))Ln(III)(NO3)2(CH3CN)]1∞·CH3CN (2Ln: Ln = Gd, Tb, Dy), where {Cu(II)L(dpen(1R2R))}(-) is (N-((1R,2R)-2-(((E)-3-ethoxy-2-oxybenzylidene)amino)-1,2-diphenylethyl)-2-oxybenzamide)copper(II) and {Cu(II)L(dpen(1R2R/1S2S))}(-) is the racemic mixture of {Cu(II)L(dpen(1R2R))}(-) and {Cu(II)L(dpen(1S2S))}(-)...
January 18, 2017: Inorganic Chemistry
https://www.readbyqxmd.com/read/28098409/trpv4-contributes-to-resting-membrane-potential-in-retinal-m%C3%A3-ller-cells-implications-in-cell-volume-regulation
#13
Vanina Netti, Juan Fernández, Maia Kalstein, Alejandro Pizzoni, Gisela Di Giusto, Valeria Rivarola, Paula Ford, Claudia Capurro
Neural activity alters osmotic gradients favoring cell swelling in retinal Müller cells. This swelling is followed by a regulatory volume decrease (RVD), partially mediated by an efflux of KCl and water. The transient receptor potential channel 4 (TRPV4), a nonselective calcium channel, has been proposed as a candidate for mediating intracellular Ca(2+) elevation induced by swelling. We previously demonstrated in a human Müller cell line (MIO-M1) that RVD strongly depends on ion channel activation and, consequently, on membrane potential (Vm )...
January 18, 2017: Journal of Cellular Biochemistry
https://www.readbyqxmd.com/read/28098324/ionic-screening-and-dissociation-are-crucial-for-understanding-chemical-self-propulsion-in-polar-solvents
#14
Aidan T Brown, Wilson C K Poon, Christian Holm, Joost de Graaf
Polar solvents like water support the bulk dissociation of themselves and their solutes into ions, and the re-association of these ions into neutral molecules in a dynamic equilibrium, e.g., H2O2 ⇌ H(+) + HO2(-). Using continuum theory, we study the influence of these association-dissociation reactions on the self-propulsion of colloids driven by surface chemical reactions (chemical swimmers). We find that association-dissociation reactions should have a strong influence on swimmers' behaviour, and therefore should be included in future modelling...
January 18, 2017: Soft Matter
https://www.readbyqxmd.com/read/28097162/antioxidant-activity-of-polyphenolic-myricetin-in-vitro-cell-free-and-cell-based-systems
#15
Abolfazl Barzegar
Myricetin (Myc) is one of the most important flavonoids in diet due to its abundance in foods with the highest antioxidant activity. The antioxidant activity of Myc was studied in cell-free and cell-based systems to evaluate the ROS protection efficiency of Myc. The studies were based on the assessment of reducing power of Myc according to ferric ion reduction and intracellular ROS level measurement by assaying the cellular fluorescence intensity using dichlorodihydrofluorescein (DCF) probe as an indicator for ROS in cells...
June 2016: Molecular Biology Research Communications
https://www.readbyqxmd.com/read/28094375/crystallization-kinetics-of-cerium-oxide-nanoparticles-formed-by-spontaneous-room-temperature-hydrolysis-of-cerium-iv-ammonium-nitrate-in-light-and-heavy-water
#16
Natasha W Pettinger, Robert E A Williams, Jinquan Chen, Bern Kohler
A stable sol of cerium oxide nanoparticles forms spontaneously when cerium(iv) ammonium nitrate (CAN) is dissolved in room-temperature water at mM concentrations. Electron microscopy experiments reveal the formation of highly crystalline cerium oxide particles several nm in diameter and suggest that they are formed from amorphous particles that are similar in size. Under the low pH conditions of the experiments, the nanoparticles form a stable dispersion and show no evidence of aggregation, even many months after synthesis...
January 17, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28094370/probing-sub-nano-level-molecular-packing-and-correlated-positron-annihilation-characteristics-of-ionic-cross-linked-chitosan-membranes-using-positron-annihilation-spectroscopy
#17
Rui Xia, Xingzhong Cao, Meizhen Gao, Peng Zhang, Minfeng Zeng, Baoyi Wang, Long Wei
Chitosan, CS, cross-linked with bivalent palladium has shown enhanced mechanical and thermal properties depending on the transformation of the structure at a microscopic scale. In the present study, CS directly cross-linked by palladium cation membranes (CS-cr-PM) was prepared through a solution-casting method. Mobility of chitosan chains were greatly reduced after crosslinking, making a great reduction in the swelling ratio studied by a water-swelling degree measurement, which led to an improvement in molecular chain rigidity...
January 17, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28093838/fusaric-acid-contributes-to-virulence-of-fusarium-oxysporum-on-plant-and-mammalian-hosts
#18
Cristina López-Díaz, Vahid Rahjoo, Michael Sulyok, Veronica Ghionna, Adela Martín-Vicente, Javier Capilla, Antonio Di Pietro, Manuel S López-Berges
Fusaric acid (FA) is among the oldest identified secondary metabolites produced by Fusarium species, known for a long time to display strong phytotoxicity and moderate toxicity to animal cells; however, the cellular targets of FA as well as its function in fungal pathogenicity remain unknown. Here, we investigated the role of FA in Fusarium oxysporum, a soil-borne cross-kingdom pathogen that causes vascular wilt on more than a hundred plant species and opportunistic infections in humans. Targeted deletion of fub1, encoding a predicted orthologue of the polyketide synthase involved in FA biosynthesis in F...
January 17, 2017: Molecular Plant Pathology
https://www.readbyqxmd.com/read/28093127/magnetic-beads-based-dna-hybridization-chain-reaction-amplification-and-dnazyme-recognition-for-colorimetric-detection-of-uranyl-ion-in-seafood
#19
Hongyan Zhang, Xian Cheng, Lian Chen, Fan Mo, LiangJun Xu, FengFu Fu
A novel colorimetric biosensor, which employs DNAzyme-functionalized magnetic beads (MBs) as recognition probe, enzyme-assisted catalytic oxidation of TMB (3,3',5,5'-tetramethylbenzidine sulfate) as signal and DNA hybridization chain reaction as amplification strategy, has been developed for detecting trace uranyl ion (UO2(2+)) in seafood and aqueous environment with high sensitivity and specificity. We demonstrated that UO2(2+) can specifically cleave DNAzyme immobilized on MBs surface to release a short single-strand DNA (primer), and the released primer trigger DNA hybridization chain reaction to form a long one dimensional DNA concatamer on the MBs surface...
March 1, 2017: Analytica Chimica Acta
https://www.readbyqxmd.com/read/28093125/hairpin-stabilized-fluorescent-silver-nanoclusters-for-quantitative-detection-of-nad-and-monitoring-nad-nadh-based-enzymatic-reactions
#20
Priyamvada Jain, Babina Chakma, Sanjukta Patra, Pranab Goswami
A set of 90 mer long ssDNA candidates, with different degrees of cytosine (C-levels) (% and clusters) was analyzed for their function as suitable Ag-nanocluster (AgNC) nucleation scaffolds. The sequence (P4) with highest C-level (42.2%) emerged as the only candidate supporting the nucleation process as evident from its intense fluorescence peak at λ660 nm. Shorter DNA subsets derived from P4 with only stable hairpin structures could support the AgNC formation. The secondary hairpin structures were confirmed by PAGE, and CD studies...
March 1, 2017: Analytica Chimica Acta
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