Advanced Materials Research Vols. 197-198

Abstract: The possibility of the existence of konjac glucomannan (KGM) single helix in dilute solution was discussed finely by ultraviolet-visible spectrophotometer (UV-Vis) with Congo red complex, viscosimetry and circular dichroism (CD). KGM bound to Congo red and the λ _max characteristic shifted markedly to longer wavelength (514 nm) in 0.25 M aq NaOH. The shifts of λ _max and intrinsic viscosity were also compared in different mediums, such as different concentrations of KGM, NaOH, urea solutions or temperatures. The results indicated that KGM had an ordered, single-helical conformation in neutral, slight NaOH (<0.15 M) and urea (<3.0 M) solutions or at a moderate temperature (T<55ºС ), while it was transformed disorder, random coils in high NaOH (>0.45 M), urea (>4.0 M) solutions or at a high temperature (T>60ºС ). So it can be conclude that the outside factors play an important role on the stability of the single-helix conformation for KGM solution. The induced CD spectra by Congo red and the CD spectra of KGM in aqueous and urea solution indicated further that KGM had a single-helical structure. The new conclusion laid the foundation of determining helical radius, pitch and length of KGM in the future studies.

Abstract: Biomorphic SnO₂/C ceramic has been prepared by molding into a composite billet and carbothermal-reduction under vacuum from ramie fibers/Sn(OH)₄ precursors. The phase composition and microstructure of the prepared samples were characterized. The effects of the carbonization temperature and the other factors on the crystal structure, morphology and ingredients of the prepared samples were discussed. The results showed that there is no peak corresponding to carbon. So, it is inferred that the carbon exists in amorphous form and the sintering temperature have significant effects on the microstructure of SnO₂ in biomorphic SnO₂/C ceramics. The prepared products at the sintering temperature between 480°C and 630°C are biomorphic SnO₂/C ceramics.

Abstract: Under the action of ultrasonic, the graft copolymer is synthesized by grafting 2, 3- glycidyl trimethyl ammonium chloride onto chitosan with ammonium cerium nitrate as initiator, and the main factors which influences this reaction are selected. The results show the optimum reactive conditions while chitosan: 2, 3- glycidyl trimethyl ammonium chloride is 1:3, pH 7.0, 70°C, the reactive time 3h, and the concentration of initiator 0.5mmol/L. Finally, the product of graft copolymer is analyzed by chemical titration, infrared analysis (IR), differential scanning calorimetry (DSC), elemental analysis, and XRD.

Abstract: Basing on analyzing aspheric curvature, considered about three effects caused by material, geometry shape and dimension of polishing tool, this paper proposed a new optimizing method for the machining tool of aspheric optics .Considering to dwell time and residual error synthetically in machining process, this method can obtain optimizing sequence of tools based on the gradient descent method, and it provides an effective reference for raising polishing accuracy and efficiency of aspheric optics.

Abstract: A new surface modification method by modifying low molecular weight ploy (L-lactide) (LMW PLLA) onto the β-tricalcium phosphate (β-TCP) superfine particles has been developed. The surface-modified β-TCP is characterized by FT-IR, XRD, digital microscope and contact angle measurement, et al. FT-IR spectra confirmed that LMW PLLA was connected onto the β-TCP surface through ionic interaction. XRD results indicated that the LMW PLLA did not affect the crystalline form of β-TCP, but the XRD patterns of the p-β-TCP showed a little difference with β-TCP. The p-β-TCP particles could be dispersed uniformly in dichloromethane. In contrast, unmodified β-TCP particles are apt to agglomerate after dispersed into dichloromethane. Wet angle measurement showed that hydrolyzed LMW PLLA significantly improves hydrophobicity of modified β-TCP particles. For the preparation of composites, PLLA was mixed with β-TCP and p-β-TCP, respectively, in a ratio of 85/15 (w/w) and moulded into tensile test specimens. Tensile tests showed that mechanical properties were improved, scanning electron microscopy (SEM) exhibited that modified β-TCP is an effective approach to prepare a homogeneous composites, moreover, it indicated a better interfacial phase interaction in the composite with the p-β-TCP. Chemical bonds between filler and PLLA matrix are assumed to be formed by ionic interaction.

Abstract: The purpose of this study was to investigate the disintegrating properties of native arrowroot starch and pregelatinized arrowroot starch in comparison with corn starch and sodium starch glycolate (Explotab®). Tablets were prepared by direct compression. The tablet formulations contained dibasic calcium phosphate as filler and magnesium stearate as lubricant. Each starch at various concentrations between 2-10 % w/w was used in formulation as disintegrant. The swelling volume and weight of starches and disintegration time of tablets were evaluated. At 2% w/w concentration of starch, the pregelatinizaed starch provided disintegration time faster than the native starch (2.5 times). The disintegration time of 2% w/w pregelatinized arrowroot starch was comparable to Explotab and faster than that of native starch. The disintegration time of native starch at the concentration of 4, 6 and 10 %w/w was comparable to that of corn starch and Explotab®. Native arrowroot starch and pregelatinized arrowroot starch could be used as effective disintegrants in tablet formulation.

Abstract: Biosorption of chromium (VI) ions from aqueous solution with fungal biomass Penicillium sp. was investigated in the batch system. The influence of contact time, solution pH, biosorbent concentration, initial concentration of Cr (VI) ions and temperature on biosorption capacity of Cr (VI) ions was studied. The uptake of Cr (VI) was highly pH dependent and the optimum pH for biosorption of Cr (VI) ions was found to be 2.0. Biosorption capacity of Cr (VI) ions decreased with increased biosorbent concentration and increased with increase in initial concentration of Cr (VI) ions. The experiment results also showed that high temperatures increased the biosorption capacity of Cr (VI) by fungal biomass. It was found that the biosorption equilibrium data were fitted very well to the kangmuir as well as to the Freundlich adsorption model. The maximum sorptive capacities obtained from the Langmuir equation at temperature of 20, 30 and 40°C were 25.91, 32.68 and 35.97 mg/g for Cr (VI) ions, respectively. The results of this study indicated that the fungal biomass of Penicillium sp. is a promising biosorbent for removal of chromium (VI) ions from the water.

Abstract: Using TiO₂ particles obtained by hydrolysis of titanium oxysulfate as the precursor, polystyrene (PS) microspheres as the template, TiO₂/PS complex particles were successfully deposited on Ti substrates through layer-by-layer self-assembly technique and the surfactant-assisted process at low temperature. Then removed PS spheres by two methods, TiO₂ hollow spheres were attained. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were employed to characterize the synthesized materials. The results showed that the crystallization, structure and surface morphology of TiO₂/PS on the surface have a great relationship with the pH value of treating solution. Diversity effects on surface integrity and bioactive of hollow spheres happened due to different ways of removing PS core.

Abstract: In this study, Box-Behnken design (BBD) and response surface analysis (RSA) methodology were employed to plan experiments and optimize the NaOH pretreatment of rice straw. Experimental results showed that concentration of NaOH (CS), treatment time (TT) and ratio of rice straw with NaOH (RS) were main factors governing the biogasification of rice straw. The polynomial equation describing the biogasification as a simultaneous function of the CS, TT and RS was confirmed. The FTIR analysis and SEM images of straws further confirmed that NaOH could disrupt the silicified waxy surface, break down the lignin-hemicellulose complex and partially remove silicon and lignin from the pretreated rice straw.

Abstract: Through the study of the effects of different dosage of additives on the properties of urea formaldehyde resin adhesive prepared at low mole ratio of formaldehyde/urea, optimize the synthetic process of the UF resin which is used at the E0 grade plywood. The results showed that the product synthesized under the following condition: the mole ratio of formaldehyde/urea is 0.99:1, the dosage of the specific additive is 1.0% and that of melamine is 3-4%, had a good comprehensive performance and the formaldehyde emission of the plywood meets the E0 grade which is environmental-friendly.