Evaluation of the decay resistance properties of Cerbera odollam extracts and their influence on properties of particleboard

Metallic-based wood preservatives currently face some restrictions over disposal and environmental issues; one possibility to develop new more benign systems is to study extractives in naturally durable woody plants. This study investigated the resistance of extracts from the leaf, fruit, wood, bark, seed and flower of Cerbera odollam to deterioration from fungus and termites. Antifungal assays with n-hexane, ethyl acetate, ethanol and methanol extracts were evaluated using paper discs. Termite mortality was evaluated with the methanol extract against Coptotermes gestroi. Physical and protective properties of particleboard impregnated with C. odollam extracts, including thickness swelling, internal bond strength, formaldehyde release, termite-decay and soil burial decay were investigated. Methanol wood extracts from C. odollam showed the highest activities against Trametes versicolor, Pycnoporus sanguineus, and Schizophyllum commune in the paper disc antifungal assay. Methanol flower extracts exhibited high performance in termite mortality, termite-decay and soil burial decay. Thickness swelling, internal bond strength and the formaldehyde emission of particleboard specimens treated with methanol extracts of C. odollam were up to the EN Standards.     

Evaluation of possible decay and termite resistance of particleboard containing waste tire rubber

Particleboard specimens produced by adding waste tire rubber particles were assayed against white- and brown-rot fungi and termites in laboratory conditions. Particleboards were manufactured from a mixture of pine and poplar particles bonded with two different resins (melamine/urea formaldehyde [MUF] and polyisocyanate [PI]) by adding waste tire rubber particles at three different levels (10%/90%, 20%/80%, and 30%/70% by weight of waste tire rubber/wood). The particleboard specimens with waste tire rubber were not generally resistant against four fungi tested. Only MUF-containing specimens showed considerably better performance in decay resistance tests using the brown-rot fungus, Postia placenta; however, addition of waste tire rubber into those specimens did not provide resistance in comparison with control specimens without tire rubber. Formosan termites were also able to degrade particleboard specimens with waste tire rubber.     

Isolation of the extractives and betulin from birch bark exposed to a microwave field

The process of isolation of the extractives and betulin from birch bark exposed to a microwave field was investigated. It was shown that under the use of microwave treatment in a microwave field the duration of the extraction process was reduced 10–15 times, as compared with the extraction by infusion. The influence of the main parameters on the process of microwave extraction of extractives from birch bark was studied. Using high performance liquid chromatography we established quantitatively the content of betulin in the birch bark extracts.     

Effects of nanowollastonite on biological resistance of particleboard made from wood chips and chicken feather against Antrodia vaillantii

The effect of wollastonite nanofibers (NW) on biological resistance of particleboard, made from wood chips and chicken-feather fibers (CF), against Antrodia vaillantii was studied. 10% of NW, as well as 5 and 10% of CF, were applied to the particleboard-matrix based on the dry weight of wood chips. Then, as a complimentary study, 10% wood fibers were also added to the wood chips; totaling, 10 mixing treatments. Specimens were prepared and mass loss (ML) values were measured in accordance with the EN 113 specifications. Results indicated that the highest ML (37%) occurred in the control treatment without NW- or CF-content; the lowest ML was seen in panels with 10% of NW, CF, and wood fibers (2.5%). NW substantially decreased ML in all mixing ratios. CF also showed a significant decreasing effect on ML. No significant correlation was found between ML values with any of physical and mechanical properties; however, high significant correlations were found between most of the mechanical properties. It is concluded that NW may be considered an effective filler in wood-composite industry to increase the durability against fungal attack; however, more studies should first be conducted on different fungi and wood and wood-composite materials to finalize this conclusion.     

Structure and mechanical properties of wet-spun fibers made from natural cellulose nanofibers

Cellulose nanofibers were prepared by TEMPO-mediated oxidation of wood pulp and tunicate cellulose. The cellulose nanofiber suspension in water was spun into an acetone coagulation bath. The spinning rate was varied from 0.1 to 100 m/min to align the nanofibers to the spun fibers. The fibers spun from the wood nanofibers had a hollow structure at spinning rates of >10 m/min, whereas the fibers spun from tunicate nanofibers were porous. Wide-angle X-ray diffraction analysis revealed that the wood and tunicate nanofibers were aligned to the fiber direction of the spun fibers at higher spinning rates. The wood spun fibers at 100 m/min had a Young's modulus of 23.6 GPa, tensile strength of 321 MPa, and elongation at break of 2.2%. The Young's modulus of the wood spun fibers increased with an increase in the spinning rate because of the nanofiber orientation effect.     

Antioxidant activity and biologic properties of a procyanidin-rich extract from pine (Pinus maritima) bark, pycnogenol.

There is growing interest in the biologic activities of plant extracts such as that obtained from the bark of the French maritime pine Pinus maritima, Pycnogenol. Pycnogenol (PYC) is a standardized extract composed of a mixture of flavonoids, mainly procyandins and phenolic acids. Studies indicate that PYC components are highly bioavailable. Uniquely PYC displays greater biologic effects as a mixture than its purified components do individually indicating that the components interact synergistically. PYC has been reported to have cardiovascular benefits, such as a vasorelaxant activity, angiotensin-converting enzyme (ACE) inhibiting activity, and the ability to enhance the microcirculation by increasing capillary permeability. Investigations of the cellular mechanisms of these therapeutic effects have demonstrated that PYC has strong free radical-scavenging activity against reactive oxygen and nitrogen species. The oligomeric components of PYC contribute significantly to the ESR free radical signal. PYC also participates in the cellular antioxidant network as indicated by its ability to regenerate the ascorbyl radical and to protect endogenous vitamin E and glutathione from oxidative stress. PYC modulates NO metabolism in activated macrophages by quenching the NO radical and inhibiting both iNOS mRNA expression and iNOS activity. The spectrum of different effects of NO in the circulation and the nervous system suggest the potential applications of PYC in immune and circulatory disorders as well as in neurodegenerative disease. PYC can bind to proteins, altering their structure and thereby modulating the activity of key enzymes and proteins involved in metabolic pathways. PYC effects redox-sensitive signal transduction pathways and alters gene expression. Aspects of PYC's activity are presented and discussed together with possible future implications and directions in the field of flavonoid research.     

Organization of the endoplasmic reticulum in dividing cells of the gymnosperms Pinus brutia and Pinus nigra,and of the pterophyte Asplenium nidus

Endoplasmic reticulum (ER) organization in the dividing cells of the pterophyte Asplenium nidus and of the gymnosperms Pinus brutia and Pinus nigra has been studied by immunolocalization techniques using the monoclonal antibody 2E7, which recognizes luminar ER resident proteins containing C-terminal HDEL sequences. In the pterophyte, the ER reorganization during cell cycle is similar to that in angiosperms. Among others, prominent ER gatherings were found at the mitotic spindle poles and in the phragmoplast during cytokinesis. However, in the gymnosperms examined, the ER displays a unique pattern of reorganization not described so far. In both the Pinus species, well-defined ER patterns are successively formed during cell cycle. They are the preprophase ER-band, the prophase- metaphase- and anaphase ER-spindle, the interzonal ER-system, the ER-phragmoplast and an ER-system lining the daughter cell wall. The ER patterns are closely similar to that of the correspondent microtubule (MT) arrangements with which they are co-organized. Observations made on P. nigra root-cells affected by oryzalin, colchicine and cytochalasin D favour the conclusion that the pattern of ER organization is controlled during mitosis and cytokinesis by the MT cytoskeleton.     

Evaluation of mold,decay and termite resistance of pine wood treated with zinc- and copper-based nanocompounds

In this work, the resistance of black pine wood (Pinus nigra L.) vacuum-treated with zinc oxide, zinc borate and copper oxide nanoparticles against mold and decay fungi and the subterranean termites was evaluated. Some of the nanocompounds tested were forced with acrylic emulsions to avoid leaching. Results showed that mold fungi were slightly inhibited by nanozinc borate, while the other nanometal preparations did not inhibit mold fungi. Mass loss from fungal attack by Trametes versicolor was significantly inhibited by the zinc-based preparations, while the brown-rot fungus, Tyromyces palustris was not inhibited by the nanometal treatments. Notably, nanozinc borate plus acrylic emulsion imparted very high resistance in pine wood to the white-rot fungus, T. versicolor with a mass loss of 1.8%. Following leaching, all pine specimens treated with nanozinc borate, with or without acrylic emulsion, strongly inhibited termite feeding, i.e. mass losses varying at 5.2–5.4%. In contrast, the copper-based treatments were much less effective against the subterranean termites, Coptotermes formosanus. In general, nanozinc borate possessed favorable properties, that is, inhibition of termite feeding and decay by T. versicolor.     

The relationships among physical,geometrical and mechanical properties of bone,with a note on the properties of nonhuman primate bone

Since bone reacts to imposed loads by formation and resorption of tissue, analysis of tissue distribution within a bone provides evidence of the adaptation of that bone to a given mechanical function. Definition of these structure-function relationships permits the physical anthropologist to clarify the wide variety of behavioral/morphological adaptations to specific ecological niches in extant primates. From this information, behavior and locomotor function can ultimately be inferred in fossil primates. This paper reviews research which shows the relationships between the physical, geometrical and mechanical properties of bone, so that researchers who are investigating the properties of bone are aware of the numerous interpretations which may be made about structure and function from basic data. In addition, this paper is an attempt to apprise investigators working with primates that comparative data on the properties of primate bone are available, though sparse.     

Mechanical properties and decay resistance of wood-polymer composites prepared from fast growing species in Turkey

Some mechanical properties of wood-polymer composites from maritime pine (Pinus pinaster Ait.) and poplar (Populus x. euramericana cv. I-214) wood were investigated. Three different monomers; styrene (ST), methyl methacrylate (MMA) and styrene/methyl methacrylate (ST/MMA) mixture were used in preparation of wood-polymer composites (WPCs). Full-loading (FL), half-loading (HL) and quarter-loading (QL) were used as polymer content levels. Untreated pine and pine-polymer composite samples were tested in compression strength parallel to grain and static bending strength. WPCs mechanical properties increased compared to untreated wood. The polymer had greater effect on the strengths of the ST/MMA treated pine than on the ST and MMA treated pine samples. Increasing of the mechanical properties should improve the structural competitiveness of WPCs made from fast growing-low density woods. Weight losses due to fungal attack for pine and poplar-polymer composites were also determined. Although polymers at full and half loading levels helped decreasing weight losses due to both fungi for each wood species, weight losses were still found to be higher.     

Chelating efficiency and thermal, mechanical and decay resistance performances of chitosan copper complex in wood-polymer composites

Wood–polymer composites (WPC) have been extensively used for building products, outdoor decking, automotive, packaging materials, and other applications. WPC is subject to fungal and termite attacks due to wood components enveloped in the thermoplastic matrix. Much effort has been made to improve decay resistance of WPC using zinc borate and other chemicals. In this study, chitosan copper complex (CCC) compounds were used as a potential preservative for wood–HDPE composites. CCC was formulated by reacting chitosan with copper salts under controlled conditions. Inductively coupled plasma (ICP) analytical results indicated that chitosan had high chelating efficiency with copper cations. CCC-treated wood–HDPE composites had a thermal behavior similar to untreated and zinc borate-treated wood–HDPE composites. Incorporation of CCC in wood–HDPE composites did not significantly influence board density of the resultant composites, but had a negative effect on tensile strength at high CCC concentration. In comparison with solid wood and the untreated wood–HDPE composites, 3% CCC-treated wood–HDPE composites significantly improved the decay resistance against white rot fungus Trametes versicolor and brown rot fungus Gloeophyllum trabeum. Especially, CCC-treated wood–HDPE composites were more effectively against the brown rot than the untreated and chitosan-treated wood–HDPE composites. Moreover, CCC-treated wood–HDPE composites performed well as zinc borate-treated wood–HDPE composites on fungal decay resistance. Accordingly, CCC can be effectively used as a preservative for WPC.     

Role of physical properties of resistance vessel wall in regulating peripheral blood flow--II. Structural and mechanical behavior

In order to examine the structural and mechanical properties of the vessel wall resistance when subjected to autoregulatory flow control, a mechanical model for the vascular wall was derived from a mathematical model. The mechanical model was an analogue model which connected in series the Maxwell model (elastic modulus: K3) with the parallel elements of Hill's model (elastic modules: K2) and Hooke's elastic model (elastic modulus: K1); it was also mathematically equivalent to the Spring model (see part I). The structural and mechanical properties of the resistance vessel wall were characterized by the three elastic moduli (K1, alpha K2 and K3) [mmHg]. The parameter alpha was a modification factor of the elastic modulus K2 given by the myogenic mechanism. After a numerical analysis of the experimental data given by the mechanical model, we confirmed that the arterial pressure range for autoregulatory flow controls shifted to the upper region with an increase of the elastic modulus K1 and the flow regulation was reduced.     

Evaluation of chemical, physical, and biologic properties of tumor-targeting radioiodinated quinazolinone derivative

Our group is developing a novel technology, enzyme-mediated cancer imaging and therapy (EMCIT), that aims to entrap radioiodinated compounds within solid tumors for noninvasive tumor detection and therapy. In this approach, a water-soluble, radioiodinated prodrug is hydrolyzed in vivo to a highly water-insoluble compound by an enzyme overexpressed extracellularly by tumor cells. We have synthesized and characterized the water-soluble prodrug, 2-(2'-phosphoryloxyphenyl)-6-[(125)I]iodo-4-(3H)-quinazolinone [(125)I]5, which is readily hydrolyzed by alkaline phosphatase, an enzyme expressed by many tumor cell lines, to a water-insoluble drug, 2-(2'-hydroxyphenyl)-6-[(125)I]iodo-4-(3H)-quinazolinone [(125)I]1. In the course of our study, we discovered that ammonium 2-(2'-phosphoryloxyphenyl)-6-tributylstannyl-4-(3H)-quinazolinone, an intermediate in the radioiodination of the prodrug, exists as two isomers (3 and 4) whose radioiodination leads, respectively, to [(125)I]6 and [(125)I]5. These prodrugs have different in vitro and in vivo biologic activities. Compound 6 is not hydrolyzed by alkaline phosphatase (ALP), whereas 5 is highly soluble (mg/mL) in aqueous solution and is rapidly dephosphorylated in the presence of ALP to 1, a water-insoluble molecule (ng/mL). Mouse biodistribution studies indicate that [(125)I]6 has high uptake in kidney and liver and [(125)I]5 has very low uptake in all normal organs. Compounds 3 and 6 are converted, respectively, to 4 and 5 after incubation in DMSO. The stability of 5 in human serum is high. The minimum ALP concentration needed to hydrolyze 5 is much greater than the ALP level in the blood of patients with cancer, and the latter should not affect the pharmacokinetics of the compound. Incubation of 5 with viable human and mouse tumor-cell lines--but not with normal human cells and mouse tissues--leads to its hydrolysis and the formation of large crystals of 1. We expect that 5 will also be hydrolyzed in vivo by tumor cells that express phosphatase activity extracellularly and anticipate the specific precipitation of radioiodinated 1 within tumor cell clusters. This should lead to high tumor-to-normal-tissue ratios and enable imaging (SPECT/PET) and radionuclide therapy of solid tumors.     

Globulixanthones C,D and E: three prenylated xanthones with antimicrobial properties from the root bark of Symphonia globulifera

Two prenylated xanthone derivatives, named globulixanthones C and D and one bis-xanthone, designated globulixanthone E, have been isolated from the root bark of Symphonia globulifera. The structures of these compounds were elucidated by a detailed spectroscopic analysis. They have been shown to exhibit in vitro significant antimicrobial activity against a range of micro-organisms.     

Photo-cross-linked PLA-PEO-PLA hydrogels from self-assembled physical networks: mechanical properties and influence of assumed constitutive relationships

Poly(lactide)-block-poly(ethylene oxide)-block-poly(lactide) (PLA-PEO-PLA) triblock copolymers are known to form physical hydrogels in water as a result of the polymer's amphiphilicity. Their mechanical properties, biocompatibility, and biodegradability have made them attractive for use as soft tissue scaffolds. However, the network junction points are not covalently cross-linked, and in a highly aqueous environment these hydrogels adsorb more water, transform from gel to sol, and lose the designed mechanical properties. In this article, a hydrogel was formed by the use of a novel two-step approach. In the first step, the end-functionalized PLA-PEO-PLA triblock was self-assembled into a physical hydrogel through hydrophobic micelle network junctions, and in the second step, this self-assembled physical network structure was locked into place by photo-cross-linking the terminal acrylate groups. In contrast with physical hydrogels, the photo-cross-linked gels remained intact in phosphate-buffered solution at body temperature. The swelling, degradation, and mechanical properties were characterized, and they demonstrated an extended degradation time (approximately 65 days), an exponential decrease in modulus with degradation time, and a tunable shear modulus (1.6-133 kPa). We also discuss the various constitutive relationships (Hookean, neo-Hookean, and Mooney-Rivlin) that can be used to describe the stress-strain behavior of these hydrogels. The chosen model and assumptions used for data fitting influenced the obtained modulus values by as much as a factor of 3.5, which demonstrates the importance of clearly stating one's data fitting parameters so that accurate comparisons can be made within the literature.