Research Articles

In North America, flooring strips are manufactured with grooves at the back. There are various reasons for these grooves but, historically, they were considered a strategy to reduce weight and transportation costs as well as improving dimensional stability. As no data are available to assess best practices in terms of performance, we have investigated methods to reduce flooring strip weight. One way to achieve this is to adjust the number and shape of grooves. Using warp as a comparison tool, we were able to analyze the merits of a finite number of designs. With this approach, however, we could not guarantee that the result was the most favourable. The search for a solution led to design optimization, i.e.: minimizing weight by acting upon a part of the strip’s shape, taking into account its warp resistance or stiffness. This paper describes an optimization strategy adapted to the calculation of the optimal design subjected to arbitrary mechanical and geometrical conditions (including the thickness of the wear layer). This approach is not limited to flooring strips, and it can be used in any situation where a linear hygromechanical model is relevant. This strategy involves two steps: global optimization with respect to admissible variations of the shape (or design) followed by a post-processing phase that takes into account various other mechanical and possibly geometrical conditions imposed on the strip.

The utilization of compost vineyard wastes as suppressive growing media against Fusarium wilt is a good alternative for the disposal and recycling of these organic wastes. Inoculation of biological control agents (BCAs) enhances the biocontrol activity of compost. In this experiment, vineyard compost was sampled at different stages during the composting process, rating the values of acceptability for growing media. Under greenhouse nursery conditions, composts inoculated with Trichoderma harzianum T-78, (Th T-78) gave higher plant fresh weights, as well as lower pathogen incidence and disease severity than treatments with Th T-78 inoculated at muskmelon sowing and non-inoculated composts. Comparing the two composts inoculated with Th T-78 at different stages of the composting process, the one inoculated at the beginning of maturation phase showed lower pathogen incidence and disease severity than the one inoculated at the beginning of the composting process.

This paper reports on the synthesis of a series of amide derivatives from acrylopimaric acid (APA). The derivatives contained aromatic groups and were characterized by IR, 1HNMR, MS, and elemental analysis. The antibacterial activity of the derivatives against Gram-negative bacteria and Gram-positive bacteria were also investigated. When compared with the other derivatives, compounds 3a and 3f showed much higher activity against Escherichia coli (Gram-negative bacteria) with inhibition zones of 5 mm and 5.5 mm, respectively. Structure-activity relationship analysis revealed that ortho-substituted phenyl derivatives and meta-substituted phenyl derivatives exhibited higher activity than the para-substituted derivatives. Meanwhile, the halogen-substituted compounds did not show visible antibacterial activity compared with other compounds, which may have been caused by the lower electron density of the halogen-substituted phenyl rings.

During the production of beer large amounts of yeast waste are generated. This paper considers the possible making of environmentally friendly adhesive compositions from such wastes. Chemical treatment of yeast wastes increases their adhesive characteristics. Chemical cross-linking with glutaric aldehyde and biological cross-linking by enzyme transglutaminase improves the moisture resistance of the adhesive compositions. In terms of their physical and mechanical parameters they are not inferior to glues of natural origin and can be used for bonding paper, cardboard, and wood. The bonding strength of paper was 421.8 N / m, and that of wood was 27.8 MPa.

With the attempt to develop an environmentally safe whey protein-based adhesive with good water resistance, a low-molecular-weight PFO was used as a modifier, and the effects of scavengers on the formaldehyde emission and bond properties were investigated. Plywood evaluation and HPLC analysis indicated that the PFO synthesized with a low content of sodium hydroxide as a catalyst (NaOH/phenol mole ratio = 0.064) at a low reaction temperature (60-75oC) had good water solubility and very low viscosity that was preferable to the modification of whey protein-based adhesives. Combinations of ammonia and sodium sulfite as formaldehyde scavengers had positive effects on the formaldehyde emissions of plywood panels bonded by the PFO-modified whey protein adhesives and had slight effects on bond properties. A necessary stoichiometric excess of ammonia-sulfite combination during PFO post-treatment is critical to effectively reduce formaldehyde emission. The whey protein-based adhesive modified with the most preferable post-treated PFO is water-resistant and environmentally safe, which had a dry shear bond strength of 1.98 MPa and a 28 hour-boiling-dry-boiling wet shear strength of 1.73 MPa according to standard JIS K6806-2003, a formaldehyde emission of 0.067mg/L according to standard JIS A5908, and undetectable level of free phenol by HPLC.

Demand for hardwood from plantation-grown stands for pulp and bio-energy in the southern US is more than 90 million tons per year and is increasing. In the specific case of bio-energy and pulp, demand for biomass from eucalypts could approach 20 million tons/year by the year 2022. Fast growing species and hybrids of Eucalyptus are being evaluated to partially fill this demand gap. Though widely grown in a number of countries for pulp as well as for bio-energy, eucalypts in the southern US have not been extensively researched. Initial growth rates of 18 to 36 green tons/ha/year on rotation lengths of 6 to 8 years are possible. Current estimated costs for energy production from eucalypts in the Southern US are estimated at $3.10 to $3.49 per MBtu, where landowner required return rates on reforestation capital invested range from 6 to 14 percent. Eucalypts as a bio-energy feedstock can be competitive with coal in cost per BTU in the southern US.

Cellulose fibres from the Juncus acutus L plant were isolated and characterized. The isolation of the fibres was performed by sequential NaOH treatment and H2O2 bleaching under different extraction conditions. The chemical and surface morphological structures of the Juncus acutus L fibres were characterized with FTIR, SEM, AFM, DSC, surface energy, diameter, density, and lignin content determination. Changes in structure and properties of the obtained fibres were observed by varying the concentration and the treatment time of the applied process. Results revealed that the optimum conditions to remove most of non-cellulosic materials from the Juncus acutus L plant were 7M NaOH, 3h and 100°C for alkaline procedure, and 10 mL.L-1 H2O2, 45 minutes and 95°C for bleaching treatment.

Graft copolymerization of Grewia optiva fiber with acrylic acid (AAc) was carried out by using a Ce(IV) redox initiator under two different conditions, i.e. in air and under the influence of microwave radiation. Different reaction conditions affecting grafting percentage (Pg) for both methods were optimized and compared. Optimized reaction parameters for maximum Pg (7.86%) for graft copolymerization of AAc onto Grewia optiva fiber in air were 90 min reaction time, a temperature of 45° C, 1.82X10-2 mol/L CAN, 2.88X10-1 mol/L nitric acid, and 3.50X10-1 mol/L AAc. However, the maximum Pg (5.56%) for graft copolymerization in the case of MWR were 15 min reaction time, 110 W power, 2.73X10-2 mol/L CAN, 2.88X10-1 mol/L nitric acid, and 2.91X10-1 mol/L AAc. Both raw and graft copolymerized fibers were subjected to the evaluation of some of their properties such as swelling, moisture absorbance, and chemical resistance behavior. The AAc-graft copolymerized Grewia optiva showed 19.23% more swelling when compared with that of raw fiber. Further morphological and structural changes, thermal stability, and the crystallanity of raw, Grewia optiva-g-poly(AAc) in air, and Grewia optiva-g-poly(AAC) under MWR fibers were also studied by SEM, FTIR, TGA, and XRD techniques.

In this work, a gene (lacP83) encoding a Pleurotus ostreatus laccase isoenzyme expressed in submerged fermentation conditions is described. A 2,887 bp sequence was obtained from a genomic library of P. ostreatus by using a PCR inverse strategy. The coding sequence, 1,527 bp long, showed 17 exons and encoded a protein of 509 amino acids, with a putative signal peptide and conserved copper binding domains. The promoter region of the lacP83 gene (466 bp upstream of ATG) contains putative binding transcription factors such as MRE, XRE, a defense response element, and a stress response element. The protein and gene sequences of lacP83 showed, respectively, 90 to 96% and 78 to 92% of similarity to laccases of Pleurotus previously reported. However, it showed differences in its apparent molecular weight and promoter sequence.

The aim of this work is to open up the structure of wood while retaining a large amount of hemicelluloses, in particular (galacto)glucomannans. The effects of pre-treatments on wood meal from spruce (Picea abies) with a reducing agent (NaBH4) combined with steam explosion at very mild conditions were investigated. The effects of steam explosion at 160 °C were studied for various residence times (5 to 35 min) on both water-impregnated wood meal and samples pre-treated with NaBH4. The findings showed that pre-treatment with sodium borohydride stabilized the reducing end-groups of glucomannans and that the treatment was effective both during mild steam explosion, for both long and short residence times, as well as during subsequent treatment in alkali. Extraction experiments at different pH and temperatures showed that the main part of the hemicelluloses still remained in the wood residue after treatment. The molecular weight distributions of the extracted material from the liquors indicated that there were broad molecular distributions and that the molecular weight averages were between 3 and 6 kDa.