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Water equilibrium

E M Varoni, S Vijayakumar, E Canciani, A Cochis, L De Nardo, G Lodi, L Rimondini, M Cerruti
Periodontal regeneration is still a challenge for periodontists and tissue engineers, as it requires the simultaneous restoration of different tissues-namely, cementum, gingiva, bone, and periodontal ligament (PDL). Here, we synthetized a chitosan (CH)-based trilayer porous scaffold to achieve periodontal regeneration driven by multitissue simultaneous healing. We produced 2 porous compartments for bone and gingiva regeneration by cross-linking with genipin either medium molecular weight (MMW) or low molecular weight (LMW) CH and freeze-drying the resulting scaffolds...
October 1, 2017: Journal of Dental Research
I Reinholds, I Pugajeva, Dz Zacs, E Lundanes, J Rusko, I Perkons, V Bartkevics
A solid-phase extraction (SPE) method based on multi-walled carbon nanotubes (CNT) was developed for the determination of 12 acidic non-steroidal anti-inflammatory drugs (NSAIDs) in surface waters and tap water. Pristine and functionalised CNTs were evaluated as sorbent materials. Batch experiments were used to optimise sorption and desorption conditions (sorbent type and amount, adsorption time, pH). The adsorption equilibrium was reached after 8 to 48 h duration, which increased with the pH of solution. Non-agglomerated pristine CNTs (20 mg) showed the most optimal adsorption (94 to 100%) for all of the analytes after a 30-min contact period in acidified water solutions (100 mL)...
October 18, 2017: Environmental Monitoring and Assessment
Belén Hernández, Fernando Pflüger, Manuel Dauchez, Mahmoud Ghomi
Water interaction with peptide chains is one of the key structure stabilizing factors in an aqueous environment. Because of its strong polar character, water can bind to both anionic and cationic sites via electrostatic interactions. It can also act as a hydrogen-bond donor or acceptor according to its interactions with different polar groups in the backbone and side chains of peptides and proteins. Based on density functional theory calculations, the present report aims at illustrating the most energetically favorable interaction sites of aromatic side chains of phenylalanine, tyrosine, tryptophan, and histidine (neutral and protonated species) with surrounding water molecules...
October 18, 2017: Physical Chemistry Chemical Physics: PCCP
Satish Patel, Shikha Srivastava, Manju Rawat Singh, Deependra Singh
Lupeol entrapped chitosan-gelatin hydrogel (LCGH) films were prepared by solution cast method by blending chitosan and gelatin solution using glycerol as plasticizer, followed by crosslinking with glutaraldehyde. LCGH films were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), equilibrium water content (EWC), Water vapor transmission rate (WVTR) and in vitro release studies. SEM confirmed presence of the uniform porous network of both blank and LCGH films...
October 13, 2017: International Journal of Biological Macromolecules
Nasreddine Benbettaïeb, Cadhla Tanner, Philippe Cayot, Thomas Karbowiak, Frédéric Debeaufort
This work deals with the study of the release kinetics of some natural antioxidants (ferulic acid, caffeic acid and tyrosol) from chitosan-fish gelatin edible films immersed ethanol at 96%, as well as the kinetics of their antioxidant activity using the DPPH assay. The aim was to determine how film functional properties influence the release kinetic and antioxidant activity. The addition of antioxidants to chitosan-fish gelatin matrix decreased the water vapour permeability by more than 30%. The tensile strength (TS) increased up to 50% after the incorporation of antioxidants...
March 1, 2018: Food Chemistry
Laura M Salonen, Sara R Pinela, Soraia P S Fernandes, João Louçano, Enrique Carbó-Argibay, Marisa P Sarriá, Carlos Rodríguez-Abreu, João Peixoto, Begoña Espiña
Phycotoxins, compounds produced by some marine microalgal species, can reach high concentrations in the sea when a massive proliferation occurs, the so-called harmful algal bloom. These compounds are especially dangerous to human health when concentrated in the digestive glands of seafood. In order to generate an early warning system to alert for approaching toxic outbreaks, it is very important to improve monitoring methods of phycotoxins in aquatic ecosystems. Solid-phase adsorption toxin tracking devices reported thus far based on polymeric resins have not been able to provide an efficient harmful algal bloom prediction system due to their low adsorption capabilities...
October 6, 2017: Journal of Chromatography. A
Liping Fang, Qiantao Shi, Jessica Nguyen, Baile Wu, Zimeng Wang, Irene M C Lo
Lanthanum-based materials are effective for sequestering phosphate in water, however their removal mechanisms remain unclear, and the effects of environmentally relevant factors have not yet been studied. Hereby, this study explored the mechanisms of phosphate removal using La(OH)3 by employing extended X-ray absorption spectroscopy (EXAFS), attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), density functional theory (DFT) and chemical equilibrium modeling. The results showed that surface complexation was the primary mechanism for phosphate removal and in binary phosphate configurations, namely diprotonated bidentate mononuclear (BM-H2) and bidentate binuclear (BB-H2), coexisting on La(OH)3 in acidic conditions...
October 16, 2017: Environmental Science & Technology
Derek Vance, Susan H Little, Corey Archer, Vyllinniskii Cameron, Morten B Andersen, Micha J A Rijkenberg, Timothy W Lyons
Isotopic data collected to date as part of the GEOTRACES and other programmes show that the oceanic dissolved pool is isotopically heavy relative to the inputs for zinc (Zn) and nickel (Ni). All Zn sinks measured until recently, and the only output yet measured for Ni, are isotopically heavier than the dissolved pool. This would require either a non-steady-state ocean or other unidentified sinks. Recently, isotopically light Zn has been measured in organic carbon-rich sediments from productive upwelling margins, providing a potential resolution of this issue, at least for Zn...
November 28, 2016: Philosophical Transactions. Series A, Mathematical, Physical, and Engineering Sciences
Dengchao Liu, Shubo Deng, Ayiguli Maimaiti, Bin Wang, Jun Huang, Yujue Wang, Gang Yu
Novel hydrated zirconium oxide (ZrO(OH)2) coated carbon nanotubes (CNTs) were prepared via a filtration-steam hydrolysis method, and were used to remove As(III) and As(V) from drinking water. This adsorbent was characterized by Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), scanning electron microscope (SEM) and transmission electron microscope (TEM). The ZrO(OH)2 coated on the surface of CNTs was amorphous, and the coating thickness was in the range of 1-8 nm. The ZrO(OH)2/CNTs nanocomposite showed high adsorption for both As(III) and As(V) with the maximum adsorption capacities of 78...
October 4, 2017: Journal of Colloid and Interface Science
Xia Luo, Sabrina S Jedlicka, Kristen L Jellison
This study investigated Cryptosporidium parvum oocyst deposition onto biofilms as a function of shear stress under laminar or turbulent flow. Annular rotating bioreactors were used to grow stabilized stream biofilms at shear stresses ranging from 0.038 to 0.46 Pa. These steady-state biofilms were then used to assess the impact of hydrodynamic condition on C. parvum oocyst attachment. C. parvum deposition onto biofilms followed a pseudo-second-order model under both laminar (after a lag phase) and turbulent flows...
October 13, 2017: Applied and Environmental Microbiology
Roy A Periana
Sushkevich et al (Reports, 5 May 2017, p. 523) report on the use of water to oxidize methane to methanol. This seems problematic because the reaction of CH4 and water to generate methanol and H2 is highly unfavorable at any temperature (ΔG of reaction ≈ +28 kcal/mol at 200°C, equilibrium constant K ≈ 10(-13)). Consequently, even if the reaction is separated into two steps, it seems inconceivable to carry out such a net reaction in a practical manner.
October 13, 2017: Science
Carmen S Mosquera-Vivas, María J Martinez, Glenda García-Santos, Jairo A Guerrero-Dallos
The adsorption-desorption, hysteresis phenomenon, and leachability of tebuconazole were studied for Inceptisol and Histosol soils at the surface (0-10 cm) and in the subsurface (40-50 cm) of an agricultural region from Colombia by the batch-equilibrium method and mathematical approaches. The experimental Kfa and Kd (L kg(-1)) values (7.9-289.2) decreased with depth for the two Inceptisols and increased with depth for the Histosol due to the organic carbon content, aryl and carbonyl carbon types. Single-point and desorption isotherms depended on adsorption reversibility and suggested that tebuconazole showed hysteresis; which can be adequately evaluated with the single-point desorption isotherm and the linear model using the hysteresis index HI...
September 30, 2017: Chemosphere
Robert H Ong, Andrew J C King, Jaap A Kaandorp, Benjamin J Mullins, M Julian Caley
A long-standing interest in marine science is in the degree to which environmental conditions of flow and irradiance, combined with optical, thermal and morphological characteristics of individual coral colonies, affects their sensitivity of thermal microenvironments and susceptibility to stress-induced bleaching within and/or among colonies. The physiological processes in Scleractinian corals tend to scale allometrically as a result of physical and geometric constraints on body size and shape. There is a direct relationship between scaling to thermal stress, thus, the relationship between allometric scaling and rates of heating and cooling in coral microenvironments is a subject of great interest...
2017: PloS One
Khurram Shehzad, Chang Xie, Junyong He, Xingguo Cai, Weihong Xu, Jinhuai Liu
Increasing exposure to arsenic (As) contaminated ground water has become a global health hazard to humanity. Suitable adsorbent for As removal from water, especially for As(III) than As(V), is an urgent but still a challenging task. In this study, waste orange peel (OP) was modified with magnetic nanoparticles followed by calcination as a novel adsorbent and investigated for instantaneous oxidation and adsorption of As(III) from aqueous solutions. The batch adsorption experimental results showed that calcined magnetic orange peel composites (CMOPC) exhibited superior As(III) adsorption capacity (10...
September 30, 2017: Journal of Colloid and Interface Science
Sumant M Avasarala, Peter C Lichtner, Abdul-Mehdi S Ali, Ricardo González-Pinzón, Johanna M Blake, Jose M Cerrato
The reactive transport of uranium (U) and vanadium (V) from abandoned mine wastes collected from the Blue Gap/Tachee Claim 28 mine site, AZ was investigated by integrating flow-through column experiments with reactive transport modelling, and electron microscopy. The mine wastes were sequentially reacted in flow-through columns at pH 7.9 (10 mM HCO3(-)) and pH 3.4 (10 mM CH3COOH) to evaluate the effect of environmentally relevant conditions encountered at Blue Gap/Tachee on the release of U and V. The reaction rate constants (km) for the dissolution of uranyl-vanadate (U-V) minerals predominant at Blue Gap/Tachee were obtained from simulations with the reactive transport software, PFLOTRAN...
October 10, 2017: Environmental Science & Technology
Nan Gao, Ming Chiu, Chiara Neto
Surface properties such as topography and chemistry affect the motion of the three-phase contact line (solid/liquid/air), which in turn affects the contact angle of a liquid moving on a solid surface. In this work, the motion of the receding water contact line was studied on chemically and topographically patterned surfaces obtained from the dewetting of thin polymer films. The patterned surfaces consisted of hydrophilic poly(4-vinylpyridine) (P4VP) bumps, which were either micro-sized and sparse or nano-sized and dense, on top of a hydrophobic polystyrene (PS) background layer...
October 10, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
Inocencio Higuera-Ciapara, Claudia Virués, Marcela Jiménez-Chávez, Evelin Martínez-Benavidez, Javier Hernández, Zaira Domínguez, Roberto López-Rendón, Enrique F Velázquez, Motomichi Inoue
Complex formation of D-glucosamine (Gl) and N-acetyl-D-glucosamine (AGl) with capsaicin (Cp) were studied by (1)H NMR titrations in H2O-d2 and DMSO-d6; capsaicin is the major bioactive component of chili peppers. Every titration curve has been interpreted by formulating a suitable model for the reaction equilibrium, to elucidate intermolecular interactions. In DMSO, glucosamine cations associate with each other to yield linear aggregates, and undergo pseudo-1:1-complexation with capsaicin, the formation constant being ca...
September 29, 2017: Carbohydrate Research
Emil Boros, Laura Jurecska, Enikő Tatár, Lajos Vörös, Marina Kolpakova
The purpose of this study was to identify the prevailing chemical composition and trophic state of the shallow saline steppe lakes of North Kazakhstan along a wide size range (< 1-454 km(2)) and salinity gradient (2-322 g L(-1)) on a large spatial scale (1000 km), taking into account the potential effects of human disturbances. Water depth, Secchi disk transparency, temperature, pH, electric conductivity, major ions, total dissolved solids, total organic carbon, total nitrogen and phosphorus, nitrate, soluble reactive phosphorus, and chlorophyll a were measured...
October 9, 2017: Environmental Monitoring and Assessment
Miroslav Havelka
The activity of (210)Pb in a solution with (210)Pb-(210)Po in the radioactive equilibrium was determined through its decay product (210)Po by liquid scintillation counting (LSC), which has, after separation, as a pure α emitting nuclide, detection efficiency practically equal to 1. For the separation of (210)Po from (210)Pb solution, two methods based on precipitation of Pb, and Pb with Bi, leaving Po in the solution, were introduced. The first one was precipitation of Pb in the form of Pb(NO3)2 from a mixture of acetic acid, toluene, water and HNO3...
September 23, 2017: Applied Radiation and Isotopes
Shaghayegh Baghaie, Mohammad T Khorasani, Ali Zarrabi, Jamal Moshtaghian
In this work, hydrogel membranes were developed based on poly vinyl alcohol (PVA), starch (St), and chitosan (Cs) hydrogels with nano Zinc oxide (nZnO). PVA/St/Cs/nZnO hydrogel membranes were prepared by freezing-thawing cycles, and the aqueous PVA/St solutions were prepared by dissolving PVA in distilled water. After the dissolution of PVA, starch was mixed, and the mixture was stirred. Then, chitosan powder was added into acetic acid, and the mixture was stirred to form a chitosan solution. Subsequently, Cs, St and PVA solutions were blended together to form a homogeneous PVA/St/Cs ternary blend solution...
October 7, 2017: Journal of Biomaterials Science. Polymer Edition
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