Volume 6 Issue 3

characteristics of differentiated xylem cells of the fast-growing 76’during the active phase by the method of differential box-counting fractal dimension. The fractal characteristics of differentiated xylem cells as well as the relationship between fractal dimension and tissues proportion were considered. Results showed that the fractal dimensions of cross sections were larger than those of tangential sections. Fractal dimension of cross sections had a remarkable negative correlation with the ratio of vessel element, significant positive correlations with the proportion of wood fiber and the proportion of parenchyma. The correlation of fractal dimension with wood fiber proportion was more significant than that with parenchyma proportion. The results were also verified by replacement of the tissues in the cross section. It was observed that fractal characteristics of the wood microstructure were very much related to the proportions of different tissues of the xylem cells.

Strand substitution was evaluated for the core of OSB with chips produced by grinding of recycled particleboards and wood waste. All the boards manufactured under laboratory conditions having a share of small chips in the core had high mechanical parameters, thus meeting the requirements of the standard for OSB/3. No significant effect was found of the applied modification of the core on bending strength or modulus of elasticity (MOE) determined for the longer axis. In turn, such properties as modulus of rupture (MOR) and MOE, determined for the shorter axis, as well as internal bond (IB) were rapidly reduced. In the case of boards containing 100% recycled chips in the core, a reduction was found in values of MOR, MOE, and IB by 45%, 30%, and 45%, respectively. In turn, the application of small chips, which previously had not been resinated, makes it possible to manufacture boards with internal bond lower by only 30%, even at the 100% substitution. Application of recycled chips produced by grinding of the P2 type particleboard did not make it possible to manufacture boards meeting the requirements of the standard after the boiling test, irrespective of the amount of small chips added to the core. Boards containing in their core small chips, which previously had not been resinated, had much better properties in this respect, since only in case of 100% substitution the manufactured boards exhibited internal bond after the boiling test lower than the requirements of the standard EN 300.

A cationic polyacrylamide (CPAM) dispersion, the copolymer of acrylamide (AM) and acryloyloxyethyltrimethyl ammonium chloride (DAC), has been synthesized through dispersion polymerization in aqueous ammonium sulfate ((NH4)2SO4) solution. The polymerization was initiated by tert-butyl hydroperoxide (TBHP) and ferrisulfas (FeSO4) using poly(dimethyl diallyl ammonium chloride) (PDMDAAC) as the stabilizer. At the optimal reaction conditions, the relative molecular weight of the CPAM dispersion was 4.2×106, its charge density was 2.2 mmol·g-1, its average particle size was 6.01 μm, and its stability and dissolvability were both excellent. The CPAM dispersion was characterized using Fourier-transform infrared (FTIR) spectroscopy, nuclear magnetic resonance (NMR) spectroscopy, and differential scanning calorimeter (DSC). Results indicated that the copolymerization was successful.

Rice husks were subjected to processing with hot, compressed water under selected conditions to cause the partial breakdown of xylan into soluble products (mainly xylooligosaccharides, XOS). The reaction media were subjected to membrane processing, endoxylanase treatment and ion exchange to obtain purified XOS concentrates. Human fecal slurry cultures with XOS were carried out to assess their bifidogenic activity to stimulate the production of Short Chain Fatty Acids (SCFA) and lactic acid. Results were compared with data obtained in similar cultures containing the prebiotic inulin and the non-prebiotic glucose. The experimental results confirmed the ability of XOS concentrates to act as fermentable carbohydrates for the human colonic microbiota, producing a rapid decrease of pH, comparable to that promoted by glucose and more pronounced than that occurring with inulin. XOS having different DP were degraded at different rates. The experimental results confirmed the ability of rice husk’s XOS concentrates for supporting the growth of bifidobacteria and for acting as carbon sources, leading mainly to the generation of acetic and lactic acids.

Structural and thermal stabilizations of poly(vinyl chloride) (PVC) and wood/PVC (WPVC) composites were studied using lead stearate (PbSt2), calcium/zinc complex (Ca/Zn) stabilizers, and methyl tin mercaptide (MT). Thermal and structural stabilities of PVC and WPVC composites were assessed using FTIR spectrometer, thermogravimetric analysis (TGA) and UV-Vis spectrophotometry. The results indicated that the additions of thermal stabilizers into PVC and WPVC composites could promote the thermal stabilities under both un-aged and thermally aged conditions. The presence of wood particles resulted in increases in polyene and carbonyl sequences during processing and decreases in the decomposition temperature (Td). The presence of wood was found to accelerate the thermal degradation in PVC, and suppressed the efficiencies of the thermal stabilizers used. By increasing the stabilizer dosage, the thermal degradations of PVC and WPVC were moderated. Under thermally aged condition at 177oC, the additions of thermal stabilizer could decrease the increase in yellowness index (YI) and discoloration at different ageing times. In this work, MT was found to be the most suitable and promising stabilizer for PVC and WPVC composites, considering the polyene and carbonyl contents, Td, the shift of derivative thermogravimetric (DTG) curves, and changes in YI value and visual color.

In the production of biofuel from lignocellulose biomass, particularly in the case of consolidated bioprocessing where the saccharification and fermentation steps take place within the same bioreactor, many compounds may be present that could affect the enzymes within such a bioreactor. This study examined the effect of ethanol, butanol, propanol, lignin, r-coumaric acid, and gallic acid on the activity of XynA from C. cellulovorans. XynA from C. cellulovorans was purified, and the effects of various compounds on enzyme activity were assayed using the dinitrosalicylic acid method. In this study, it was found that XynA was very tolerant to ethanol and only lost 25% of activity even at high concentrations of ethanol. In the presence of lignin, XynA was inhibited at very low levels and retained ~85% of its activity. The highest degree of inhibition of XynA was experienced in the presence of r-coumaric acid (38%) and gallic acid (47%). The results indicate that the most problematic compounds within the bioreactor are likely to be soluble lignin degradation products resulting from pretreatment steps. Therefore, the removal of these compounds prior to saccharification should result in increased productivity within a bioreactor. This study indicates that XynA may be a suitable hemicellulase for use in bioethanol production, as it has very high tolerance for ethanol inhibition.

The alkaline-tolerant marine-derived fungus Chaetomium globosum was tested for the production of enhanced levels of cellulases and free phenolics under highly alkaline conditions using agro wastes (cotton seed, sugar cane bagasse) as substrates under solid state fermentation (SSF) processes. In both the agro wastes used, an increase in cellulases (β-endoglucanase, β-Glucosidase, and β-exoglucanase) production was observed with increase in pH. This enhanced carbohydrate-hydrolyzing enzymes (β-endoglucanase, β-Glucosidase and β-exoglucanase) and thereby enriched the total phenolic release from agro-wastes under SSF conditions of higher pH. A linear correlation was observed between released total phenolic contents of agro-wastes and total antioxidant property. The increased antioxidant activity on free radical scavenging was also observed with the increase in pH. Thus, the present study makes it possible to produce nutraceutical ingredients cost-effectively from agricultural wastes.

Bagasse is a by-product of the sugarcane milling process, and it also is an important fuel resource for that industry. In this study an attempt has been made to utilize this by-product to prepare a composite using epoxy resin. The fibers surface was modified by alkali treatment with 5% NaOH solution for 0, 2, 4 and 6 hrs. The effect of fiber surface modification on the mechanical properties such as flexural strength of the composites was investigated with the fibers as received from the milling process. It was found that alkali-treated bagasse/epoxy composites significantly improved the flexural strength of the composite. An SEM investigation also indicated that the surface modifications improved the fiber–matrix interaction.

The test panels obtained from Scots pine (Pinus sylvestris L.) and Eastern beech (Fagus orientalis L.) were initially adjusted to have 8%, 10%, and 12% moisture content in this study. One-component semi-matte and two-component water borne varnishes were applied on the surfaces in order to investigate the effect of the type and the moisture content of the wood on the hardness and the gloss values as well as the adhesion strength of the varnishes. The hardness of the test samples was evaluated based on the standard ANS/ISO1522, the gloss based on TS.4318 EN ISO 2813, and the adhesive strength based on ASTM D-4541. The results indicated that variations in the moisture content of the wood material adversely affected the layer performance of water-borne varnishes and that the best performance was obtained for the wood with moisture contents of 8% and 10%.

Surface roughness and wettability of flat-pressed wood plastic composites (WPCs) incorporated with various fire retardants (FRs) (5, 10, or 15% by weight (wt)) at 50 wt-% content of the wood flour (WF) were investigated. The most common FRs, zinc borate (ZB), magnesium hydroxide (MH), and ammonium polyphosphate (APP), were used in the experiments. The WPC panels were made from dry-blended wood flour (WF), fire retardant (FR) powder, and polypropylene (PP) powder with maleic anhydride-grafted PP (2 wt-%) formulations using a conventional flat-pressing process under laboratory conditions. The contact angle measurements were obtained by using a goniometer connected with a digital camera and computer system. Three roughness measurements, average roughness (Ra), mean peak-to-valley height (Rz), and maximum roughness (Ry), were taken from the WPC panel surface using a fine stylus tracing technique. It was found that the surface smoothness of the WPC panels decreased with increasing content of the FR powder while the wettability increased. The control WPC panel without the FR had the smoothest surface, followed by the WPC panels containing the MH, ZB, and APP, respectively.