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https://www.readbyqxmd.com/read/28813107/climatic-characteristics-of-the-2010-2016-drought-in-the-semiarid-northeast-brazil-region
#1
José A Marengo, Lincoln M Alves, Regina C S Alvala, Ana Paula Cunha, Sheila Brito, Osvaldo L L Moraes
This study discusses the climatological aspects of the most severe drought ever recorded in the semiarid region Northeast Brazil. Droughts are recurrent in the region and while El Nino has driven some of these events others are more dependent on the tropical North Atlantic sea surface temperature fields. The drought affecting this region during the last 5 years shows an intensity and impact not seen in several decades in the regional economy and society. The analysis of this event using drought indicators as well as meteorological fields shows that since the middle 1990s to 2016, 16 out of 25 years experienced rainfall below normal...
August 14, 2017: Anais da Academia Brasileira de Ciências
https://www.readbyqxmd.com/read/28812987/a-microneedle-functionalized-with-polyethyleneimine-and-nanotubes-for-highly-sensitive-label-free-quantification-of-dna
#2
Darius Saadat-Moghaddam, Jong-Hoon Kim
The accurate measure of DNA concentration is necessary for many DNA-based biological applications. However, the current methods are limited in terms of sensitivity, reproducibility, human error, and contamination. Here, we present a microneedle functionalized with polyethyleneimine (PEI) and single-walled carbon nanotubes (SWCNTs) for the highly sensitive quantification of DNA. The microneedle was fabricated using ultraviolet (UV) lithography and anisotropic etching, and then functionalized with PEI and SWCNTs through a dip coating process...
August 16, 2017: Sensors
https://www.readbyqxmd.com/read/28812902/charge-effects-on-the-efflorescence-in-single-levitated-droplets
#3
Gunter Hermann, Yan Zhang, Bernhard Wassermann, Henry Fischer, Marcel Quennet, Eckart Ruehl
The influence of electrical excess charges on the crystallization from supersaturated aqueous sodium chloride solutions is reported. This is accomplished by efflorescence studies on single levitated microdroplets using optical and electrodynamic levitation. Specifically, a strong increase in efflorescence humidity is observed as a function of the droplet's negative excess charge, ranging up to -2.1 pC, with a distinct threshold behavior, increasing the relative efflorescence humidity, at which spontaneous nucleation occurs, from 44% for the neutral microparticle to 60%...
August 16, 2017: Journal of Physical Chemistry. A
https://www.readbyqxmd.com/read/28812872/effect-of-mineral-dissolution-precipitation-and-co2-exsolution-on-co2-transport-in-geological-carbon-storage
#4
Ruina Xu, Rong Li, Jin Ma, Di He, Peixue Jiang
Geological carbon sequestration (GCS) in deep saline aquifers is an effective means for storing carbon dioxide to address global climate change. As the time after injection increases, the safety of storage increases as the CO2 transforms from a separate phase to CO2(aq) and HCO3(-) by dissolution and then to carbonates by mineral dissolution. However, subsequent depressurization could lead to dissolved CO2(aq) escaping from the formation water and creating a new separate phase which may reduce the GCS system safety...
August 16, 2017: Accounts of Chemical Research
https://www.readbyqxmd.com/read/28812870/antifouling-thermoplastic-composites-with-maleimide-encapsulated-in-clay-nanotubes
#5
Ye Fu, Congcong Gong, Wencai Wang, Liqun Zhang, Evgenii Ivanov, Yuri M Lvov
An antifouling ethylene-vinyl acetate copolymer (EVA) with halloysite clay nanotubes loaded with maleimide (TCPM) is prepared. Such encapsulation allowed for extended release of TCPM and a long-lasting, efficient protection of the coated surface against marine microorganisms proliferation. Halloysite also induces the composite's anisotropy due to parallel alignment of the nanotubes. The maleimide loaded halloysite incorporated into the polymer matrix allowed for 12-month release of the bacterial inhibitor preventing fouling; it is much longer than the 2-3 month protection when TCPM is directly admixed into EVA...
August 16, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28812746/redox-titration-of-gold-and-platinum-surface-oxides-at-porous-microelectrodes
#6
Mareike Haensch, Julian Behnken, Luis Balboa, Alexander Dyck, Gunther Wittstock
The extension of the surface interrogation mode of scanning electrochemical microscopy (SI-SECM) is demonstrated for porous electrode materials. These materials are often high surface area powders which are very important electrocatalysts for instance in fuel cells or water electrolyzers. The powdered electrocatalyst material is filled into a cavity-microelectrode which is then operated as the sample electrode in SECM. After a surface oxide generation step, the oxides on the porous sample are reduced by [Ru(NH3)6](2+) formed at the microelectrode probe of the SECM while the sample is at open circuit potential...
August 16, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28812363/influence-of-oxygen-vacancies-on-the-frictional-properties-of-nanocrystalline-zinc-oxide-thin-films-in-ambient-conditions
#7
Huan-Pu Chang, En-De Chu, Yu-Ting Yeh, Yueh-Chun Wu, Fang-Yuh Lo, Wei-Hua Wang, Ming-Yau Chern, Hsiang-Chih Chiu
Oxygen vacancy is the most studied point defect and has been found to significantly influence the physical properties of zinc oxide (ZnO). By using atomic force microscopy (AFM), we show that the frictional properties on the ZnO surface at the nanoscale greatly depend on the amount of oxygen vacancies present in the surface layer and the ambient humidity. The photocatalytic effect (PCE) is used to qualitatively control the amount of oxygen vacancies in the surface layer of ZnO and reversibly switch the surface wettability between hydrophobic and superhydrophilic states...
August 16, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/28812348/inhibition-of-heterogeneous-ice-nucleation-by-bioinspired-coatings-of-polyampholytes
#8
Zhiyuan He, Liuchun Zheng, Zhenqi Liu, Shenglin Jin, Chuncheng Li, Jianjun Wang
Controlling of heterogeneous ice nucleation (HIN) on foreign surfaces is of great importance for anti-ice nucleation material design. In this work, we studied the HIN behaviors on various ion-modified poly(butylene succinate) (PBS) surfaces via chain-extension reaction. Inspired by antifreeze proteins (AFPs), the PBS-based polyampholytes, containing both negative and positive charge groups on a single chain, show excellent performance of ice nucleation inhibition and freezing delay. Unlike the extremely high price and low availability of AFPs, these PBS-based polyampholytes can be commercially synthesized under mild reaction conditions...
August 16, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28812195/design-and-evaluation-of-a-compact-photocatalytic-reactor-for-water-treatment
#9
Marko Kete, Olena Pliekhova, Lev Matoh, Urška Lavrenčič Štangar
A compact reactor for photocatalytic oxidation and photocatalytic ozonation water treatment was developed and evaluated by using four model pollutants. Additionally, combinations of pollutants were evaluated. Specially produced Al2O3 porous reticulated monolith foams served as TiO2 carriers, offering a high surface area support. UV lamps were placed in the interior to achieve reduced dimensions of the reactor (12 cm in diameter × 20 cm in height). Despite its small size, the overall photocatalytic cleaning capacity was substantial...
August 15, 2017: Environmental Science and Pollution Research International
https://www.readbyqxmd.com/read/28812194/amorphous-silica-promoted-lysine-dimerization-a-thermodynamic-prediction
#10
Norio Kitadai, Kumiko Nishiuchi, Akari Nishii, Keisuke Fukushi
It has long been suggested that mineral surfaces played a crucial role in the abiotic polymerization of amino acids that preceded the origin of life. Nevertheless, it remains unclear where the prebiotic process took place on the primitive Earth, because the amino acid-mineral interaction and its dependence on environmental conditions have yet to be understood adequately. Here we examined experimentally the adsorption of L-lysine (Lys) and its dimer (LysLys) on amorphous silica over a wide range of pH, ionic strength, adsorbate concentration, and the solid/water ratio, and determined the reaction stoichiometries and the equilibrium constants based on the extended triple-layer model (ETLM)...
August 15, 2017: Origins of Life and Evolution of the Biosphere
https://www.readbyqxmd.com/read/28812178/sludge-quantification-at-water-treatment-plant-and-its-management-scenario
#11
Tarique Ahmad, Kafeel Ahmad, Mehtab Alam
Large volume of sludge is generated at the water treatment plants during the purification of surface water for potable supplies. Handling and disposal of sludge require careful attention from civic bodies, plant operators, and environmentalists. Quantification of the sludge produced at the treatment plants is important to develop suitable management strategies for its economical and environment friendly disposal. Present study deals with the quantification of sludge using empirical relation between turbidity, suspended solids, and coagulant dosing...
August 15, 2017: Environmental Monitoring and Assessment
https://www.readbyqxmd.com/read/28812092/effect-of-ligand-structure-on-the-size-control-of-mono-and-bi-thiolate-protected-silver-nanoclusters
#12
Kaiyuan Zheng, Xun Yuan, Jianping Xie
Ligand structure could control the size and structure of thiolate-protected silver nanoclusters (Ag NCs) in water. Small alkane-thiols, medium-sized aromatic-thiols, and bulky thiol-containing tri-peptides direct the formation of Ag25(SR)18, Ag44(SR)30, and Ag9-15(SR)5-10, respectively. In addition, small alkane-thiol collocates well with other types of thiolate ligand to generate bi-thiolate-protected Ag25 NCs with controlled ligand landscapes on their surfaces.
August 16, 2017: Chemical Communications: Chem Comm
https://www.readbyqxmd.com/read/28811303/adaptive-camouflage-what-can-be-learned-from-the-wetting-behaviour-of-the-tropical-flat-bugs-dysodius-lunatus-and-dysodiusmagnus
#13
Florian Hischen, Vladislav Reiswich, Desirée Kupsch, Ninon De Mecquenem, Michael Riedel, Markus Himmelsbach, Agnes Weth, Ernst Heiss, Oskar Armbruster, Johannes Heitz, Werner Baumgartner
The neotropical flat bug species Dysodius lunatus and Dysodius magnus show a fascinating camouflage principle, as their appearance renders the animal hardly visible on the bark of trees. However, when getting wet due to rain, bark changes its colour and gets darker. In order to keep the camouflage effect, it seems that some Dysodius species benefit from their ability to hold a water film on their cuticle and therefore change their optical properties when also wetted by water. This camouflage behaviour requires the insect to have a hydrophilic surface and passive surface structures which facilitate the liquid spreading...
August 15, 2017: Biology Open
https://www.readbyqxmd.com/read/28811117/bilayered-buccal-films-as-child-appropriate-dosage-form-for-systemic-administration-of-propranolol
#14
Angela Abruzzo, Fiore Pasquale Nicoletta, Francesco Dalena, Teresa Cerchiara, Barbara Luppi, Federica Bigucci
Buccal mucosa has emerged as an attractive site for systemic administration of drug in paediatric patients. This route is simple and non-invasive, even if the saliva wash-out effect and the relative permeability of the mucosa can reduce drug absorption. Mucoadhesive polymers represent a common employed strategy to increase the contact time of the formulation at the application site and to improve drug absorption. Among the different mucoadhesive dosage forms, buccal films are particularly addressed for paediatric population since they are thin, adaptable to the mucosal surface and able to offer an exact and flexible dose...
August 12, 2017: International Journal of Pharmaceutics
https://www.readbyqxmd.com/read/28811032/recent-advancements-and-future-trends-in-environmental-analysis-sample-preparation-liquid-chromatography-and-mass-spectrometry
#15
REVIEW
Virginia Pérez-Fernández, Lucia Mainero Rocca, Pierpaolo Tomai, Salvatore Fanali, Alessandra Gentili
Among the thousands of chemicals having potential to enter the environment, the NORMAN network has identified at least 700 substances categorized into 20 classes in the European surface waters. Pesticides, pharmaceuticals, disinfection by-products, wood preservation and industrial chemicals are the prominent classes. Since the impact of these substances on aquatic life and human health might be dramatic, action is urgently required at multiple levels; one of them is just related to the development of more and more sensible and selective analytical methods...
August 29, 2017: Analytica Chimica Acta
https://www.readbyqxmd.com/read/28811019/introducing-a-new-and-rapid-microextraction-approach-based-on-magnetic-ionic-liquids-stir-bar-dispersive-liquid-microextraction
#16
Alberto Chisvert, Juan L Benedé, Jared L Anderson, Stephen A Pierson, Amparo Salvador
With the aim of contributing to the development and improvement of microextraction techniques, a novel approach combining the principles and advantages of stir bar sorptive extraction (SBSE) and dispersive liquid-liquid microextraction (DLLME) is presented. This new approach, termed stir bar dispersive liquid microextraction (SBDLME), involves the addition of a magnetic ionic liquid (MIL) and a neodymium-core magnetic stir bar into the sample allowing the MIL coat the stir bar due to physical forces (i.e., magnetism)...
August 29, 2017: Analytica Chimica Acta
https://www.readbyqxmd.com/read/28811016/activated-biochar-preparation-characterization-and-electroanalytical-application-in-an-alternative-strategy-of-nickel-determination
#17
Cristiane Kalinke, Paulo Roberto Oliveira, Geovane Arruda Oliveira, Antonio Sálvio Mangrich, Luiz H Marcolino-Junior, Márcio F Bergamini
This work reports for the first time the use of chemically activated biochar as electrode modifier for nickel determination. The biochar activation was performed by refluxing with HNO3, which promoted a higher nickel preconcentration compared to unmodified and modified biochar precursor electrodes. Morphological and structural characterization revealed the increase of surface acid groups, surface area and porosity of biochar after activation. Nickel determination was investigated adopting an alternative voltammetric methodology based on monitoring the Ni(II)/Ni(III) redox couple...
August 29, 2017: Analytica Chimica Acta
https://www.readbyqxmd.com/read/28810787/transforming-high-dimensional-potential-energy-surfaces-into-sum-of-products-form-using-monte-carlo-methods
#18
Markus Schröder, Hans-Dieter Meyer
We propose a Monte Carlo method, "Monte Carlo Potfit," for transforming high-dimensional potential energy surfaces evaluated on discrete grid points into a sum-of-products form, more precisely into a Tucker form. To this end we use a variational ansatz in which we replace numerically exact integrals with Monte Carlo integrals. This largely reduces the numerical cost by avoiding the evaluation of the potential on all grid points and allows a treatment of surfaces up to 15-18 degrees of freedom. We furthermore show that the error made with this ansatz can be controlled and vanishes in certain limits...
August 14, 2017: Journal of Chemical Physics
https://www.readbyqxmd.com/read/28810776/perspective-surface-freezing-in-water-a-nexus-of-experiments-and-simulations
#19
Amir Haji-Akbari, Pablo G Debenedetti
Surface freezing is a phenomenon in which crystallization is enhanced at a vapor-liquid interface. In some systems, such as n-alkanes, this enhancement is dramatic and results in the formation of a crystalline layer at the free interface even at temperatures slightly above the equilibrium bulk freezing temperature. There are, however, systems in which the enhancement is purely kinetic and only involves faster nucleation at or near the interface. The first, thermodynamic, type of surface freezing is easier to confirm in experiments, requiring only the verification of the existence of crystalline order at the interface...
August 14, 2017: Journal of Chemical Physics
https://www.readbyqxmd.com/read/28810743/layer-by-layer-molecular-assemblies-for-dye-sensitized-pho-toelectrosynthesis-cells-prepared-by-atomic-layer-deposi-tion
#20
Degao Wang, Matthew V Sheridan, Bing Shan, Byron H Farnum, Seth L Marquard, Benjamin D Sherman, Michael S Eberhart, Animesh Nayak, Christopher Dares, Atanu Das, R Morris Bullock, Thomas J Meyer
In a Dye Sensitized Photoelectrosynthesis Cell (DSPEC) the relative orientation of the catalyst and chromophore plays an important role in determining the device efficiency. Here we introduce a new, robust atomic layer deposition (ALD) procedure for the preparation of molecular chromophore-catalyst assemblies on wide bandgap semiconductors. In this procedure, solution deposited, phosphonate derivatized metal complexes on metal oxide surfaces are treated with reactive metal reagents in the gas phase by ALD to form an outer metal ion bridging group which can bind a second phosphonate containing species from solution to establish a R1-PO2-O-M-O-PO2-R2 type surface assembly...
August 15, 2017: Journal of the American Chemical Society
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