关键词： chlorhexidine   oral hygiene   oral irrigator   sonic toothbrush   titanium surface  

摘要： ObjectivesTo investigate the cleaning efficacy of a mechanical and a hydrodynamic homecare device on biofilm-coated titanium surfaces with and without chlorhexidine. Material and methodsSix-species biofilms were grown on 108 SLA-titanium discs, which were cleaned as follows: sonic toothbrush alone (i) or in combination with either a 0.2% chlorhexidine (ii) or a placebo gel (iii) and oral irrigator (hydrodynamic action) with water (iv) or combined with 0.2% chlorhexidine solution (v). Untreated samples served as control (vi). Biofilms were then harvested either immediately after treatment (study part A) or after a regrowth phase of 24h (study part B) and colony-forming units (CFU) were assessed. Results were analysed using Whitney U-tests between the treatment groups. After the Bonferroni correction, the significance level was set at =0.0033. ResultsThe median CFU counts directly after instrumentation accounted - in ascending order (P-values in comparison with the control group A6 were <0.001 for all groups except for A3: P=0.014) - 2.0E1 (A5), 1.1E5 (A4), 3.6E5 (A2), 3.3E5 (A1) and 6.8E6 (A3), respectively. The untreated control group showed the highest CFU counts: 1.8E7 (A6). After regrowth, the following CFU counts were measured in ascending order (all P-values <0.001 when compared to the control group B6=2.0E8): 1.6E2 (B5), 1.9E5 (B2), 1.4E7 (B4), 3.1E7 (B1) and 3.9E7 (B3). ConclusionsAn oral irrigator combined with 0.2% chlorhexidine is effective in reducing biofilms attached to rough titanium surfaces immediately after cleaning. Following a regrowth phase of 24h, micro-organisms could be equally effective removed with a sonic toothbrush combined with 0.2% chlorhexidine and an oral irrigator with 0.2% chlorhexidine.

关键词： Actin   Cadherins   Developmental biology   Mechanotransduction  

摘要： During epithelial morphogenesis, E-cadherin adhesive junctions play an important part in mechanically coupling the contractile cortices of cells together, thereby distributing the stresses that drive cell rearrangements at both local and tissue levels. Here we discuss the concept that cellular contractility and E-cadherin-based adhesion are functionally integrated by biomechanical feedback pathways that operate on molecular, cellular and tissue scales.

关键词： iron powder   milling   mechanical alloying   dislocation structure   shrinkage   sintering kinetics   activation energy of sintering   Ivensen equation  

摘要： The sintering kinetics is investigated and the activation energy of sintering of milled powders of iron and mechanically alloyed mixture "iron-0.5% carbon-5.6% ferrophosphorus" is calculated. The dislocation density increasing to 10(11) cm(-2) is calculated by X-ray phase analysis and metallography, and ordering of dislocations in milled powders of iron and mechanically alloyed mixture upon increasing the milling time is found. Based on the values of porosity, which vary during isothermal sintering at 900-1100A degrees C in powders milled in different times, coefficients of the Ivensen equation and activation energy of sintering and concentration of structural defects, which are present in the beginning of isothermal sintering, are calculated. The results of investigations showed that the formation upon milling the dislocation structure with a high density of thermally unstable dislocations slightly activates sintering, and structural defects formed during the formation of solid solutions during mechanical alloying and heterodiffusion affect the activation of sintering much more strongly.

关键词： Three-dimensional axially moving beams   Nonlinear dynamics   Thermo-mechanical dynamics   Stability  

摘要： The thermo-mechanical nonlinear dynamics of a three-dimensional axially moving beam is examined numerically in this paper. Hamilton's principle is employed to derive the nonlinear partial differential equations governing the motion of the system in the longitudinal, transverse, and lateral directions. The discretized equations of motion, which are in the form of second-order nonlinear ordinary differential equations, are obtained by applying the Galerkin technique to the nonlinear partial differential equations of motion. A change of variables is introduced to this set of equations, yielding a set of first-order nonlinear ordinary differential equations. The pseudo-arclength continuation technique is employed to solve this set of equations numerically so as to construct the frequency-response curves;this method allows continuation of both stable and unstable solution branches. The effect of modal interactions on the resonant dynamic behaviour of a fully symmetrical system (about the centreline) is also examined.

关键词： GLYPHOSATE   RESEARCH   SOIL composition   ORTHOPHOSPHATES   NUCLEAR magnetic resonance spectroscopy   GLYCINE  

摘要： Glyphosate [N-( phosphonomethyl) glycine] is a broad-spectrum systemic herbicide. Because of the ever-increasing application of glyphosate in agricultural fields and detection of its presence in soils and environmental waters, there is a growing concern that it may potentially harm animal and human populations and the environment. In this study, we determined the mechanism and reaction pathway of birnessite-catalyzed degradation of glyphosate by using one-dimensional (H-1, C-13, and P-31) and two-dimensional homo- and hetero-nuclear NMR correlation spectroscopies. The NMR results showed the presence of several degradation products including orthophosphate, aminomethylphosphonic acid (AMPA), glycine, and sarcosine. Two-dimensional NMR and correlation spectroscopies confirmed the identity of products and contaminants in the reactions. Our results show that the glyphosate degradation reaction is very fast, with the majority of reaction products formed within 1 min of reaction. Degradation depends linearly on the birnessite concentration, indicating sorption as the prerequisite for glyphosate degradation. Based on the reaction kinetics and NMR data, we propose two glyphosate degradation pathways: one starts with C-P bond cleavage and the other with C-N bond cleavage. Interestingly, the dominance of one pathway over the other was found to vary with the birnessite/glyphosate ratio. This information could be exploited further to identify conditions under which glyphosate degradation occurs primarily under the C-P bond cleavage pathway because this pathway does not produce AMPA, a compound with a longer half-life than glyphosate and with known animal and plant toxicity.

关键词： BAMO-AMMO/DIANP composite   MD simulation   Compatibility   Mechanical property  

摘要： To investigate the plasticizing effect of DIANP (1,5-diazido-3-nitrazapentane, an azido plasticizer) on the tri-block copolymer BAMO-AMMO (3,30-bisazidomethyloxetane-co-3-azidomethyl-30-methyloxetane, an energetic binder), various BAMO-AMMO/DIANP composites with the mass ratio of 66.9/33.1 (I), 49.2/50.8 (II), and 32.9/67.1 (III) were investigated using molecular dynamic (MD) simulations. First, different BAMO-AMMO copolymers were constructed and the one with the suitable ratio was screened. Then, the compatibility, intermolecular interactions, and mechanical properties of the BAMO-AMMO/DIANP composites were studied. It is found that DIANP has a good miscibility with BAMO-AMMO and can effectively improve the mechanical properties of BAMO-AMMO. III has the best tenacity and ductility and the lowest rigidity among three blends due to its highest intermolecular interactions. This work provides a practical guidance to the use of DIANP as a plasticizer in the BAMO-AMMO composites. (C) 2015 Elsevier B.V. All rights reserved.

关键词： 2,4-diChlorobenzaldehyde (2,4-diCB)  

摘要： Permagnetic oxidation of 2,4-diChlorobenzaldehyde has been studied at different temperatures using spectrophotometer under acidic conditions. The effect of variation of substrate (2,4-diCB), oxidant (KMnO4) and H2SO4 was studied under pseudo first order reaction conditions. The effect of different salts on oxidation of 2,4-diCB was also studied. The reaction was found to be first order with respect to oxidant, substrate and H2SO4. A suitable mechanism is also suggested for the oxidation reaction. [ABSTRACT FROM AUTHOR]

关键词： Young's modulus   Molecular dynamics   Graphene   TiO2 (rutile)   Hybrid nanocomposites   Hydroxyl groups  

摘要： In this paper, the molecular dynamics (MD) simulations were used to investigate the mechanical properties of a single graphene layer, a TiO2 (rutile) crystal structure, hybrid graphene/TiO2 (rutile) nanocomposite and hybrid hydroxylated graphene/TiO2 (rutile) nanocomposite. The Young's modulus, shear and bulk moduli, Poisson's ratio, lame constants and compressibility of these four structures have been computed using the COMPASS, Dreiding and Universal molecular mechanics force fields through the Forcite module of Accelrys Materials Studio 7 software. The results for both graphene and TiO2 (rutile) obtained from Dreiding and Universal force fields are in good agreement with experimental and molecular dynamics results from earlier literature. Although the COMPASS force field is a good candidate for determination of mechanical properties of graphene, it is not applicable for studying the elastic properties of crystalline forms of TiO2 to compare with previous studies. This shows that the Dreiding and Universal force fields are preferred over the COMPASS force field for studying the mechanical properties of hybrid graphene/titania (rutile) nanocomposites. The MD simulations based on the Dreiding and Universal force fields showed that the interaction between the graphene and rutile TiO2 surfaces increases Young's modulus and shear modulus of TiO2. (C) 2015 Elsevier B.V. All rights reserved.

关键词： stimuli-sensitive polymers   biomaterials   drug delivery systems  

摘要： Two series of pH-sensitive semi-interpenetrating network hydrogels (semi-IPN) based on chitosan (CS) natural polymer and acrylamide (AAm) and/or N-hydroxymethyl acrylamide (HMA) monomers by varying the monomer and CS ratios were synthesized by free radical chain polymerization. 5-Fluorouracil (5-FU), a model anticancer drug, has been added to the feed composition before the polymerization. The characterization of gels indicated that the drug is molecularly dispersed in the polymer matrix. The swelling kinetics of drug-loaded gels have decreased with increased HMA content at 37 degrees C in both distilled water and buffer solutions with a pH of 2.1 or 7.4. Elastic modulus of the gels increased with the increase in HMA content and higher CS concentration enhanced the elastic modulus positively. Moreover, cumulative release percentages of the gels for 5-FU were ca. 10% higher in pH 2.1 than those in pH 7.4 media. It was determined that they can be suitable for the use in both gastric and colon environments. (C) 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41886.

关键词： HEAT transfer   MOLECULAR dynamics -- Simulation methods   SHEARING force   THERMAL conductivity   SURFACE tension  

摘要： Experiments have shown a dependence of the thermal conductivity of soft polymer materials on shear stress, which is common to several applications, such as film processing, fiber spinning, blow molding, and vacuum forming. Experiments reveal that the conductivity initially decreases with shear, but then increases as additional shear rate is applied. Based on molecular principles, we hypothesize that when molecules are initially placed under tension and extended, they disentangle, which reduces the number of points of interaction and diminishes the heat flux. Further molecular stretching increases this flux because the molecules are now better axially aligned. Molecular dynamics simulations confirm this competition and reproduce the inflection in the flux-strain relationship, which has not been previously explained. (C) 2015 Elsevier B.V. All rights reserved.