Advanced Materials Research Vols. 183-185

Abstract: Using the steam exploded pretreatment technology to process the corn stalk, and then the pretreated corn stalk were used the materials of anaerobic fermentation under the temperature 35°C. Experimental results show that: the biogas production per unit of pretreated corn stalk increased 16.8 % ~ 63.2% than the unexploded corn stalk. The gas production can up to the peak (484.3ml / g dry steam exploded straw) under the condition (retained time 90s, pressure 3.0Mpa). The longer the retained time is the earlier the gas production peak occurs under the same steam pressure and the peak range become wider. The main gas production area is the former 20d, the production amount to about 80% of total production, while the gas production of untreated straw fermentation in is only 60% of total production under medium temperature.

Abstract: The application and development of FRP bars for reinforce concrete structures necessitates the need for either adopt the current code method or exploiting a new design one to account for the properties of FRP materials. The method for predicting deflection of concrete beams with FRP bars in ACI440 is based on the method for that with steel bars in ACI318. Similarly, a modified method based on GB50010 is proposed in this paper to estimate deflection of concrete beams with FRP bars. Furthermore, the new method, together with ACI318, ACI440 and GB50010 ones, are verified by nine test beams in three existing experiment and show a good agreement with the experimental data. Simultaneously, the new method is also proved to be of the most precise and accurate one and indicates the potential of the method to estimate deflection in Chinese code system.

Abstract: Under steam curing condition, there is significant increment in the porosity of concrete. For the purpose of reducing porosity of steam-cured concrete and improving the durability of steam-cured precast elements, this paper carried out contrastive experiments including two curing condition (steam curing and standard curing), simultaneously considering the effect of different binders type, investigated the porosity change of steam curing and standard curing concretes with mineral admixtures. The corresponding mechanism was also discussed. Results indicated that, taking replace of 30% cement with double-mixing fly ash and silica fume achieves the lowest steam-cured concrete porosity. Steam curing technological measures exert a significant influence on the steam-cured concrete unclosed top suface porosity. For the characteristics of different concrete mixtures, the same steam curing technological measures exert different influence. For the same concrete, adopting appropriate technological measures can greatly decreased the porosity of concrete surface to be exposed, especially for concrete with high water-binder ratio.

Abstract: A facile and environment-friendly sonochemical route to fabricate well-defined Fe3O4/Pt and γ-Fe2O3/Pt composite microspheres under mild conditions has been reported. The structure and morphology of the synthetic spherical-shaped Fe3O4/Pt and γ-Fe2O3/Pt products were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM) with selected area electron diffraction (SAED). The results revealed that the composites were spherical with diameter in the range of 50–80 nm and had an ordered face-centered cubic (fcc) structure of platinum. These nanocomposites with platinum-coated iron oxide can be applied in a variety of areas, including medicine, photonics, new functional device assemblies and catalysis especially for fabricating some magnetic-responsive catalyst.

Abstract: Hollow porous magnetite spheres were synthesized by a simple solvothermal route with controllable size ranging from 80 nm to 400 nm. The size, shell thickness and the interior space of the resulted crystals were controlled by reaction time, molar ratio of ammonium bicarbonate (NH4HCO3) and ammonium acetate (NH4Ac). The structure, morphology, size, and magnetic properties of the hollow porous magnetite spheres were investigated. The characterizations of Scanning electron microscopy (SEM) and Transmission electron microscopy (TEM) images showed that ratio of NH4HCO3 and NH4Ac, and molar concentration of ammonium played an important role in the morphology, size and magnetic property of the porous hollow sphere. Meanwhile, reaction time strongly influenced in the porous structure and interior space of hollow porous magnetite spheres.

Abstract: The dyeability of PLA fabric with the natural emodin dye has been investigated. The effect of different factors, which are dyeing temperature, dyeing time, dye bath pH value, bath ratio, dye concentration and mordants, has been studied. The color of each dyed sample was evaluated in terms of the K/S value, and the color fastness to soaping and crocking were tested according to the ISO standards. The results showed that the dyed fabrics have a bright color and an excellent color fastness. As a result, emodin dyes PLA is a good approach to develop “green clothes” and has broad prospect.

Abstract: With the depletion of fossil energy, biology material is getting more and more attention. Bark, as a kind of renewable resource, need to be utilized urgently and reasonably. The larch bark was very extensive in northeast and the use of larch bark is limited to make tannin. However, the whole process produced much bark residue, which could not be utilized effectively. In this paper, based on the content of total phenolic hydroxyl groups, the in-situ synthesis reaction of the larch bark with formaldehyde was performed in different ratios. FTIR analysis was adopted to characterize the synthesized products. After air-drying, the synthesized product was pressed into a bark-based composite under pressure of 10~25 MPa. The effect of pressure and molar ratio of phenols and formaldehyde on the properties of the composite were analyzed. These results indicate that, pressure and molar ratio were both vital factors. The composite with higher molar ratio of phenol and formaldehyde had better abilities of anti-moisture, but the molar ratio of 1:2 made the strongest composite. With the increasing of pressure, the hardness of the composite was greater. For the composite made under 20 MPa and the molar ratio of 1:2, its hardness was 23.41 MPa and its max load was 415.83N. Its thickness and diameter swelling rate of moisture absorption in 12 d was 1.87% and 0.68%.

Abstract: In this study, three extractives from China-fir heartwood were obtained by sequential extraction processes with hexane, ethyl acetate and methanol. The antifungal activities of three extractives against two wood decay fungi (Trametes versicolor and Gloeophyllum trabeum) and two wood stain fungi (Paecilomyces variotii and Aspergillus niger) were evaluated with digging-hole method. The results showed that none of the three extracts had good antifungal activities against these four fungi. Among the three extracts, the hexane one was the most effective and the methanol extract was the second. The ethyl acetate extract, to some degree, stimulated the growth of wood decay fungi. Judging from antifungal activities of extracts, the combination of extracts rather than any single compound is important for China-fir durability. The cubes of China-fir heartwood went through a sequential extraction processes with hexane, ethyl acetate and methanol in Soxhlet extractor. The wood decay resistances of non-extracted and extracted heartwood blocks against Trametes versicolor and Gloeophyllum trabeum were evaluated after steam sterilization according to the Chinese standard method. Non-extracted heartwood blocks were resistant to Trametes versicolor but experienced substantial weight losses when exposed to Gloeophyllum trabeum. Weight losses increased after hexane extraction, but then declined markedly after ethyl acetate extraction. The possible explanation for the declined weight losses of ethyl acetate extracted blocks could be that some components which stimulated the growth of these fungi, especially Trametes versicolor were extracted by ethyl acetate. After extraction with methanol, weight losses of the blocks by Gloeophyllum trabeum increased dramatically but weight losses of the blocks by Trametes versicolor were similar to those of the ethyl acetate extracted blocks.

Abstract: Using Zero-span tensile test technique, measurements of the longitudinal tensile strength of tracheids of brown-rotted Chinese fir were obtained in the present work. The results showed that the longitudinal tensile strength of tracheids reduced with the increase of exposure time. The absolute value of reduced tensile strength was not remarkable because of low degradation efficiency. The FTIR spectroscopy results shows that brown-rot fungus did degraded the cellulose and hemicellulose of Chinese fir, explaining the reduction of tensile strength of tracheids. The intensities of the characteristic aromatic lignin peak at 1512 cm-1 was not increased but decreased, which was very strange, hinting the reason of that is not clearly illustrate by the FTIR spectra only.

Abstract: The nanocomposite membranes were prepared by mixing 2.5 wt% of TiO2 nanoparticles in casting solution. In order to determine the nanocomposite membrane property, a long-term operation of membrane bioreactor (MBR) was carried out and membrane flux were measured though the filtration tests. Results showed that TiO2 addition significantly improved the permeability of membrane and decreased the cake resistance compared with the sulfonated polyethersulfone (SPES) membrane in MBR.