Reply to Comment on 'Diffusion of water and sodium counter-ions in nanopores of β-lactoglobulin crystal: a molecular simulation study'

The analysis in Hu and Jiang's Comment to our paper cannot reveal long-time diffusion, and incorrectly led the authors to conclude that the diffusion in beta-lactoglobuline is anomalous. In?this context, the limitations of applying a mean-square displacement analysis to short, heterogeneous pore channels are discussed. A more appropriate approach based on first-passage time analysis is illustrated by a detailed analysis of water motion in a natural membrane protein channel. The partitioning and the motion of water molecules between core and surface hydration layers is discussed. Finally, the calculation of the water density profile is commented?upon.     

Tragacanth gum-graft-polyacrylonitrile: synthesis,characterization and hydrolysis

A large number of cyanide functional groups were introduced onto the carbohydrate biopolymer tragacanth gum to yield hydrophobic graft copolymer, tragacanth gum-g-polyacrylonitrile. Thus, graft copolymerization of monomer acrylonitrile (AN) was carried out under nitrogen atmosphere using ceric ammonium nitrate (CAN) as an initiator. The highest percentage of grafting (543%) and the lowest homopolymer content (10%) were achieved through a systematic optimization of the polymerization variables, including reaction time, temperature, and concentration of CAN, AN and the gum. Evidence of grafting was examined by comparing FTIR spectra. The optimally prepared tragacanth gum-g-polyacrylonitrile copolymer was also characterized thermally and morphologically. It was hydrolyzed in alkaline medium to achieve an in-situ crosslinked hybrid network with ultra high water absorption capacity (swelling in water, 30700%; swelling in saline, 6550%). The swelling characteristic of the semi-synthetic super-absorbent hydrogel was preliminarily investigated. The chemical structure, thermal characteristics and morphology of the hydrogel hybrid product were briefly studied.     

CNT/PDMS composite membranes for H2 and CH4 gas separation

Polydimethylsiloxane (PDMS) composites with different weight amounts of multi-walled carbon nanotubes (MWCNT) were synthesised as membranes to evaluate their gas separation properties. The selectivity of the membranes was investigated for the separation of H₂ from CH₄ gas species. Membranes with MWCNT concentrations of 1% increased the selectivity to H₂ gas by 94.8%. Furthermore, CH₄ permeation was almost totally blocked through membranes with MWCNT concentrations greater than 5%. Vibrational spectroscopy and X-ray photoelectron spectroscopy techniques revealed that upon the incorporation of MWCNT a decrease in the number of available Si–CH₃ and Si–O bonds as well as an increase in the formation of Si–C bonds occurred that initiated the reduction in CH₄ permeation. As a result, the developed membranes can be an efficient and low cost solution for separating H₂ from larger gas molecules such as CH₄.     

Induced superabsorbency in polyester fiber

Modified polyester fibers are considered as a significant part of the polyester produced throughout the world due to the new properties and also reduced undesirable properties, compared to non-modified polyester fibers. In this study, the modification of polyester fiber properties was evaluated for its superabsorbency. The fibers obtained superabsorbency by their treatment with a special latex prepared by inverse emulsion polymerization. Different polymer latexes based on acrylic acid, sodium acrylate, acrylamide (AM) and 2-acrylamide-2-methyl propane sulfonic acid were prepared using inverse emulsion polymerization. Chemical bond (or hydrogen bond) was formed between the functional groups of the fiber surface and functional groups present in the polymer latex by heating. The modified fibers were characterized by swelling, mechanical, morphological, and thermal measurements. The effect of several modifications of parameters such as latex type, AM content in latex, aquatic-organic phase ratios of latex, modification time and modification temperature on the swelling properties of fibers were investigated. Water absorption of the unmodified fiber was 1.5 g/g which increased up to 75 g/g, significantly. This considerable development in hydrophilic characteristics of polyester fibers has led to water blocking of the fiber. Such modification did not have adverse effects on the tensile properties or thermal resistance of the polyester fiber.     

Atomically thin layers of MoS2 via a two step thermal evaporation-exfoliation method

Two dimensional molybdenum disulfide (MoS(2)) has recently become of interest to semiconductor and optic industries. However, the current methods for its synthesis require harsh environments that are not compatible with standard fabrication processes. We report on a facile synthesis method of layered MoS(2) using a thermal evaporation technique, which requires modest conditions. In this process, a mixture of MoS(2) and molybdenum dioxide (MoO(2)) is produced by evaporating sulfur powder and molybdenum trioxide (MoO(3)) nano-particles simultaneously. Further annealing in a sulfur-rich environment transforms majority of the excess MoO(2) into layered MoS(2). The deposited MoS(2) is then mechanically exfoliated into minimum resolvable atomically thin layers, which are characterized using micro-Raman spectroscopy and atomic force microscopy. Furthermore Raman spectroscopy is employed to determine the effect of electrochemical lithium ion exposure on atomically thin layers of MoS(2).     

Superabsorbent hydrogel composites and nanocomposites: A review

Superabsorbent polymers are hydrophilic networks that can absorb and retain huge amounts of water or aqueous solutions. They are currently used in many areas including hygienic and bio‐related uses (particularly in disposable diapers), agricultural uses (e.g., water reserving in soil, soil conditioning, and controlled release of agrochemicals), pharmaceutical dosage forms, separation technology, fibers/textiles, water‐swelling rubbers, soft actuators/valves, electrical, construction, packaging, artificial snow, sludge/coal dewatering, fire‐extinguishing gels, etc. Addition of clays and organo‐modified clays into superabsorbent formulation has funded new generations of these hydrogels, i.e., superabsorbent hydrogel composites (SHCs) and superabsorbent hydrogel nanocomposites (SHNCs). New superabsorbent hydrogels are cheaper in price, and possess superior mechanical properties than non‐composite counterparts. This review introduces the SHC and SHNC polymers with the focus on different minerals and humic additives, synthetic methods, the hydrogel characteristics and their applications. POLYM. COMPOS., 2011. © 2010 Society of Plastics Engineers     

Effect of Flank Wear on the Topography of Machined Surfaces

The effect of flank wear on the topography of machined surfaces is investigated by studying its effect on the shape of the tool nose. For this purpose, turning experiments were performed to produce surfaces corresponding to different levels of flank wear. The distribution of flank wear at the tool nose during these experiments caused the nose radius to decrease, which when replicated on the machined surface resulted in narrower and deeper feedmarks. This change in the geometry of feedmarks was represented by the increase in the arithmetic average roughness of the surface profile heights.     

Hydroxymethyl furfural-modified urea–formaldehyde resin: synthesis and properties

Considering the importance of urea–formaldehyde (UF) resins in the wood industry, this work reports on a new bio-based modification of UF resins. The use of 5-hydroxymethyl furfural (HMF) is motivated by the current concerns about the effects of formaldehyde on human health. UF and urea–HMF–formaldehyde (UHF) resins were synthesized by an alkaline-acid method and characterized by FTIR, thermogravimetric analysis, and differential scanning calorimetry. The UHF, as a newly modified polymeric resin, was thermally characterized, and it was found that its thermo-stability and char yield was improved. In order to investigate the performance of the UHF, the preparation of particleboards with the UHF as adhesive, as well as its film formation ability have been studied. The UHF films formed on wood panels were uniform without any crack. Film formation ability of the UHF resin was improved due to the presence of more hydroxyl groups as well as furan rings of the HMF moieties resulting in more activated groups to be bonded by wood. Furthermore, formaldehyde release of the particleboards bonded by UHF was significantly lower than that of which bonded by the UF resin. Lab particleboards using the UHF resins showed higher modulus of rupture, modulus of elasticity, and internal bond compared to boards with UF resins, as well as lower water absorption and thickness swelling. Based on these results UHF resin can be considered as a possible candidate as adhesive for wood and wood based panels.