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https://www.readbyqxmd.com/read/27923492/hydrogen-bonding-interactions-and-enthalpy-relaxation-in-sugar-protein-glasses
#1
Bulat Sydykov, Harriëtte Oldenhof, Harald Sieme, Willem F Wolkers
In this study, hydrogen bonding interactions and enthalpy relaxation phenomena of sugar and sugar/protein glasses have been studied using Fourier transform infrared spectroscopy and differential scanning calorimetry. The sugar OH band in Fourier transform infrared spectra was used to derive the glass transition temperature, Tg, and the wavenumber-temperature coefficient (WTC) of the OH band. A study on mixtures of sucrose and albumin revealed that the glass transition temperature and strength of hydrogen bonds increased with increasing percentages of albumin...
December 3, 2016: Journal of Pharmaceutical Sciences
https://www.readbyqxmd.com/read/27920900/polyelectrolyte-coating-on-superparamagnetic-iron-oxide-nanoparticles-as-interface-between-magnetic-core-and-biorelevant-media
#2
Etelka Tombácz, Katalin Farkas, Imre Földesi, Márta Szekeres, Erzsébet Illés, Ildikó Y Tóth, Daniel Nesztor, Tamás Szabó
Nanoparticles do not exist in thermodynamical equilibrium because of high surface free energy, thus they have only kinetic stability. Spontaneous changes can be delayed by designed surface coating. In biomedical applications, superparamagnetic iron oxide nanoparticles (SPIONs) require an optimized coating in order to fulfil the expectation of medicine regulatory agencies and ultimately that of biocompatibility. In this work, we show the high surface reactivity of naked SPIONs due to ≡Fe-OH sites, which can react with H(+)/OH(-) to form pH- and ionic strength-dependent charges...
December 6, 2016: Interface Focus
https://www.readbyqxmd.com/read/27919781/budgie-in-the-mirror-an-exploratory-analysis-of-social-behaviors-and-mirror-use-in-the-budgerigar-melopsittacus-undulatus
#3
Daniel P Buckley, Michael R Duggan, Matthew J Anderson
Despite their prevalent use amongst avian species, particularly in Budgerigars, the relationship between mirror use and social behaviors is in need of elucidation. After establishing social behavior measures (e.g., agonistic and pair-bond data) in a colony of Budgerigars, mirrors were introduced and subsequent use was documented. Results illustrated a significant relationship between mirror use and pair-bonds, such that mirror use increased with increasing pair-bond strength. The authors posit that individual differences in gregariousness may best account for the obtained results, with certain birds seeking more social stimulation than others, whether it be from a pair-bond or from its own reflected mirror image...
December 2, 2016: Behavioural Processes
https://www.readbyqxmd.com/read/27918620/use-of-gallic-acid-to-enhance-the-antioxidant-and-mechanical-properties-of-active-fish-gelatin-film
#4
Kanokrat Limpisophon, Gerhard Schleining
This study explores the potential roles of gallic acid in fish gelatin film for improving mechanical properties, UV barrier, and providing antioxidant activities. Glycerol, a common used plasticizer, also impacts on mechanical properties of the film. A factorial design was used to investigate the effects of gallic acid and glycerol concentrations on antioxidant activities and mechanical properties of fish gelatin film. Increasing the amount of gallic acid increased the antioxidant capacities of the film measured by radical scavenging assay and the ferric reducing ability of plasma assay...
December 5, 2016: Journal of Food Science
https://www.readbyqxmd.com/read/27918042/straintronics-in-two-dimensional-in-plane-heterostructures-of-transition-metal-dichalcogenides
#5
Wei Wei, Ying Dai, Baibiao Huang
For in-plane heterostructures between 2D transition-metal dichalcogenides (TMDs), namely, MoSe2/MoS2, MoS2/MoSe2, WSe2/MoS2 and MoS2/WSe2, intrinsic strain can be introduced resulting from lattice mismatch between two constituents, which significantly influences electronic properties (straintronics). Intrinsic strain can reduce or decrease the coupling strength between nonmetal p and metal d orbitals, and therefore modifies the splitting between bonding and antibonding states at the high-symmetry k-points. In this case, relative upward or downward shift of band edge at specific k-points leads to band gap reduction or enhancement and the indirect-direct band gap transition...
December 5, 2016: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/27916947/preparation-of-a-bis-gma-free-dental-resin-system-with-synthesized-fluorinated-dimethacrylate-monomers
#6
Shuzhen Luo, Wenbin Zhu, Fang Liu, Jingwei He
With the aim of reducing human exposure to Bisphenol A (BPA) derivatives in dentistry, a fluorinated dimethacrylate monomer was synthesized to replace 2,2-bis[4-(2-hydroxy-3-methacryloy-loxypropyl)-phenyl]propane (Bis-GMA) as the base monomer of dental resin. After mixing with reactive diluent triethyleneglycol dimethacrylate (TEGDMA), fluorinated dimethacrylate (FDMA)/TEGDMA was prepared and compared with Bis-GMA/TEGDMA in physicochemical properties, such as double bond conversion (DC), volumetric shrinkage (VS), water sorption (WS) and solubility (WSL), flexural strength (FS) and modulus (FM)...
December 1, 2016: International Journal of Molecular Sciences
https://www.readbyqxmd.com/read/27915020/multifunctions-of-dual-zn-mg-ion-co-implanted-titanium-on-osteogenesis-angiogenesis-and-bacteria-inhibition-for-dental-implants
#7
Yiqiang Yu, Guodong Jin, Yang Xue, Donghui Wang, Xuanyong Liu, Jiao Sun
In order to improve the osseointegration and long-term survival of dental implants, it is urgent to develop a multifunctional titanium surface which would simultaneously have osteogeneic, angiogeneic and antibacterial properties. In this study, a potential dental implant material-dual Zn/Mg ion co-implanted titanium (Zn/Mg-PIII) was developed via plasma immersion ion implantation (PIII). The Zn/Mg-PIII surfaces were found to promote initial adhesion and spreading of rat bone marrow mesenchymal stem cells (rBMSCs) via the upregulation of the gene expression of integrin α1 and integrin β1...
November 30, 2016: Acta Biomaterialia
https://www.readbyqxmd.com/read/27910991/structural-fingerprints-of-yielding-mechanisms-in-attractive-colloidal-gels
#8
Arman Boromand, Safa Jamali, João M Maia
Core-Modified Dissipative Particle Dynamics (CM-DPD) with a modified depletion potential and full hydrodynamics description is used to study non-equilibrium properties of colloidal gels with short range attraction potentials at an intermediate volume fraction (ϕ = 0.2) under start-up shear deformation. Full structural and rheological analysis using the stress fabric tensor complemented by bond number and bond distribution evolution under flow reveals that similarly to dilute colloidal gels, flow-induced anisotropy and strain-induced stretching of bonds are present during the first yielding transition...
December 2, 2016: Soft Matter
https://www.readbyqxmd.com/read/27908715/development-and-characterization-of-bacterial-cellulose-reinforced-biocomposite-films-based-on-protein-from-buckwheat-distiller-s-dried-grains
#9
Xuejiao Wang, Niamat Ullah, Xuchun Sun, Yan Guo, Lin Chen, Zhixi Li, Xianchao Feng
Biocomposite films were manufactured by combining protein extracted from buckwheat distiller's dried grains with bacterial cellulose (BC). The film microstructures showed that BC is compatible with protein matrix and endows the film with high rigidity. Differential scanning calorimetry (DSC) showed that BC can promote thermal stability of the composite films. BC promoted the transition from a Newtonian to a non-Newtonian fluid and the shear thinning behavior of protein-BC solution. Fourier Transform Infrared (FTIR) spectroscopy showed the main functional groups' absorption peaks shifted to lower wavenumbers...
November 28, 2016: International Journal of Biological Macromolecules
https://www.readbyqxmd.com/read/27906492/taming-metal-fluorine-carbenoids
#10
Sebastian Molitor, Kai-Stephan Feichtner, Viktoria H Gessner
While Li/Cl carbenoids are versatile reagents in organic synthesis, the controlled handling of the extremely reactive and labile M/F carbenoids remains a challenge. We now show that even these compounds can be stabilized and isolated in solid state as well as in solution. Particularly the sodium and potassium com¬pounds exhibit a remarkable stability, thus allowing the first isolation of a room temperature stable fluorine carbenoid. Spectro¬scopic as well as DFT studies confirm the pronounced carbenoid character, showing M-F-C interactions with elongated C-F bonds...
December 1, 2016: Chemistry: a European Journal
https://www.readbyqxmd.com/read/27906491/influence-of-alcohol-%C3%AE-fluorination-on-hydrogen-bond-acidity-of-conformationally-flexible-substrates
#11
Jerome Graton, Guillaume Compain, François Besseau, Elena Bogdan, Joe Watts, Lewis Mtashobya, Zhong Wang, Alex Weymouth-Wilson, Nicolas Galland, Jean-Yves Le Questel, Bruno Linclau
Rational modulations of molecular interactions are of significant importance in compound properties optimization. We have previously shown that fluorination of conformationally rigid cyclohexanols leads to attenuation of their hydrogen-bond (H-bond) donating capacity (pKAHY) when OH***F intramolecular hydrogen-bond (IMHB) interactions occur, as opposed to an increase in pKAHY due to the fluorine electronegativity. This work has now been extended to a wider range of aliphatic β-fluorohydrins with increasing degrees of conformational flexibility...
December 1, 2016: Chemistry: a European Journal
https://www.readbyqxmd.com/read/27906483/electrochemical-oxidation-and-radical-cations-of-structurally-non-rigid-hypervalent-silatranes-theoretical-and-experimental-studies
#12
Valery Fedorovich Sidorkin, Elena Fedorovna Belogolova, Yu Wang, Viatcheslav Jouikov, Evgeniya Pavlovna Doronina
Using 18 silatranes XSi(OCH2CH2)3N (1) as an example, the potentials of electrochemical oxidation E0 of the hypervalent compounds of Si were calculated for the first time at the ab initio and DFT levels. The experimental peak potentials Ep show an excellent agreement (MAE = 0.03) with the MP2//B3PW91 calculated E0 (C-PCM). Radical cations of 1 reveal a "stretch isomerism" of the NSi dative bond. Localization of the spin density (SD) on the substituent X and the short (s) coordination contact Si…N (dSiN < 2...
December 1, 2016: Chemistry: a European Journal
https://www.readbyqxmd.com/read/27905598/dehydro-oxazole-thiazole-and-imidazole-radicals-insights-into-the-electronic-structure-stability-and-reactivity-aspects
#13
Anamika Mukhopadhyay, Lilit Jacob, Sugumar Venkataramani
DFT (U)B3LYP/cc-pVTZ and (U)M06-2X/cc-pVTZ and multireference CASSCF/cc-pVTZ level of theories have been used to investigate the electronic structure of isomeric dehydrooxazole (1b-d, 3 isomers), dehydrothiazole (2b-d, 3 isomers) and dehydroimidazole (3a-d, 4 isomers) radicals. The ground state electronic structure of each radical isomer has been confirmed by predicting their doublet excited state structure and calculating the adiabatic energy difference. The stability order of the individual isomeric radicals has been estimated through the comparison of absolute energies...
December 1, 2016: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/27905587/the-premolten-layer-of-ice-next-to-a-hydrophilic-solid-surface-correlating-adhesion-with-molecular-properties
#14
Jonathan F D Liljeblad, István Furó, Eric C Tyrode
In order to establish the potential correlation between the macroscopic ice adhesion and the molecular properties of the premolten layer (PML), the adhesion strength between ice and hydrophilic silica has been measured as a function of temperature. In addition, temperature-dependent molecular properties have been determined using techniques that are sensitive to different aspects of the PML, specifically total internal reflection (TIR) Raman, vibrational sum frequency (VSFS) and NMR spectroscopies. The ice shear adhesion strength was observed to increase linearly with decreasing temperature until -25 °C, where a plateau marked the adhesive strength having reached the cohesive strength of ice...
December 1, 2016: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/27904899/dependence-of-magnetic-coupling-on-ligands-at-the-axial-positions-of-ni-ii-in-phenoxido-bridged-dimers-experimental-observations-and-dft-studies
#15
Monotosh Mondal, Sanjib Giri, Pampa M Guha, Ashutosh Ghosh
A nickel(ii) complex [Ni2L(R)2(CH3CN)4](ClO4)2·2CH3CN (1) has been synthesized by using a tridentate reduced Schiff base ligand, HL(R), 2-[(3-methylamino-propylamino)-methyl]-4-nitrophenol and Ni(ClO4)2·6H2O. Stoichiometrically controlled addition of NH4SCN to the acetonitrile-water solution of 1 produced two other complexes, [Ni2L(R)2(μ1,1-NCS)(CH3CN)2](ClO4)·CH3CN (2) and [Ni2L(R)2(NCS)2 (CH3CN)2] (3) by replacing one and two coordinated CH3CN by NCS(-), respectively. The dinuclear Ni(II) complexes 1 and 3 are structurally very similar containing a diphenoxido bridge between the Ni(II) ions...
December 1, 2016: Dalton Transactions: An International Journal of Inorganic Chemistry
https://www.readbyqxmd.com/read/27904091/erratum-to-application-of-addition-cured-silicone-denture-relining-materials-to-adjust-mouthguards
#16
Shintaro Fukasawa, Hiroshi Churei, Ruman Uddin Chowdhury, Takahiro Shirako, Sharika Shahrin, Abhishekhi Shrestha, Takahiro Wada, Motohiro Uo, Hidekazu Takahashi, Toshiaki Ueno
The purposes of this study were to examine the shock absorption capability of addition-cured silicone denture relining materials and the bonding strength of addition-cured silicone denture relining materials and a commercial mouthguard material to determine its applicability to mouthguard adjustment. Two addition-cured silicone denture relining materials were selected as test materials. The impact test was applied by a free-falling steel ball. On the other hand, bonding strength was determined by a delamination test...
2016: Dental Materials Journal
https://www.readbyqxmd.com/read/27904087/push-out-bond-strength-of-a-new-post-system-after-various-post-space-treatments
#17
Melek Akman, Ayçe Unverdi Eldeniz, Selen Ince, Mehmet Burak Guneser
To assess the effect of post-space treatment with chelating agents on the push-out bond-strength of a glass fiber post-system. Fortyeight human teeth were decoronated. The roots were prepared to size 40 and obturated. The post-spaces were prepared with PeesoReamer drills. The post-spaces were irrigated with (i) NaOCl and EDTA with chlorhexidine (QMix), (ii) NaOCl and EDTA, (iii) NaOCl and Citric acid, (iv) NaOCl and saline as a control group. i-TFC glass fiber posts were then luted with i-TFC bond system. The samples were horizontally sectioned...
2016: Dental Materials Journal
https://www.readbyqxmd.com/read/27904030/formulation-optimization-and-in-vitro-characterization-of-orally-disintegrating-films-using-a-factorial-design-and-mathematical-modeling-for-drug-release
#18
Yeongbin Lee, Prakash Thapa, Seong Hoon Jeong, Mi Hee Woo, Du Hyung Choi
Even though experimental designs are becoming popular especially for conventional dosage forms, limited studies have been performed to optimize formulations of orally disintegrating films (ODFs). This study aimed to evaluate sildenafil citrate-loaded ODFs for a controlled release with hydroxypropyl methylcellulose as a film-forming polymer. A factorial design was utilized for optimization with three control factors: ethanol ratio, plasticizer ratio, and the type of plasticizer. Tensile strength, disintegration time, water contact angle, and thickness were chosen as responses...
November 30, 2016: Chemical & Pharmaceutical Bulletin
https://www.readbyqxmd.com/read/27903776/social-bond-strength-influences-vocally-mediated-recruitment-to-mobbing
#19
Julie M Kern, Andrew N Radford
Strong social bonds form between individuals in many group-living species, and these relationships can have important fitness benefits. When responding to vocalizations produced by groupmates, receivers are expected to adjust their behaviour depending on the nature of the bond they share with the signaller. Here we investigate whether the strength of the signaller-receiver social bond affects response to calls that attract others to help mob a predator. Using field-based playback experiments on a habituated population of wild dwarf mongooses (Helogale parvula), we first demonstrate that a particular vocalization given on detecting predatory snakes does act as a recruitment call; receivers were more likely to look, approach and engage in mobbing behaviour than in response to control close calls...
November 2016: Biology Letters
https://www.readbyqxmd.com/read/27900918/modification-of-gellan-gum-films-by-halloysite-physicochemical-evaluation-and-drug-permeation-properties
#20
Duangkamon Sakloetsakun, Thaned Pongjanyakul
The aims of this study were to determine the potential of gellan gum (GG) and halloysite (HS) dispersions at different mixing ratios and investigate the potential of GG-HS dispersions in film formation. To this end, the dispersions and films were characterized. The dispersions formed films with large particles ranging from 3-4 µm in size, with a zeta potential of approximately -35 mV. The GG-HS films were fabricated using a solvent-casting technique, which generated films with a white opaque appearance and rough surface...
November 30, 2016: Drug Development and Industrial Pharmacy
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