Comparative analysis of a wood: adhesive bondline

The wood–adhesive interface was analyzed using five methods with the objective of quantitatively assessing penetration of adhesive into the porous wood network. Methods included fluorescence microscopy, scanning electron microscopy, backscatter electron imaging, wavelength dispersive spectroscopy, and X-ray microtomography (XMT). Each method provided a visual inspection, and all of the analysis methods were applied to the same field of view. XMT was the primary technique of interest. Rubidium hydroxide was used in place of sodium hydroxide in the formulation of phenol–formaldehyde adhesive. Rubidium was found to increase the X-ray attenuation of the adhesive. However, rubidium migrated beyond the adhesive interphase during specimen preparation, thus reducing its effectiveness for image contrast enhancement. The wood species studied included red oak (Quercus rubra), Douglas-fir (Pseudotsuga menziesii), and hybrid poplar (Populus deltoides × Populus trichocarpa). All techniques used for this study were useful, but each presented some limitations for bondline analysis. Despite the problem with rubidium migration, XMT for this application was promising.     

Titanium Dioxide Nanoparticle Circulation in an Aquatic Ecosystem

Nanotechnology is a dynamically developing field of scientific and industrial interest across the entire world, and the commercialization of nanoparticles (NPs) is rapidly expanding. Incorporation of nanotechnologies into a range of manufactured goods results in increasing concern regarding the subsequent release of engineered NPs into the environment. One of the biggest threats of using NPs is the transfer and magnification of these particles in the trophic chain. The aim of the studies was the evaluation of the distribution of TiO₂ NP contamination in the aquatic ecosystem under laboratory conditions. Bioaccumulation of TiO₂ NPs by plants (Elodea canadensis) and fish (Danio rerio) in the source of contamination was investigated. The studies were focused on the consequences of short-term water contamination with TiO₂ NPs and the secondary contamination of the components of the investigated model ecosystem (plants, sediments). It was found that in the fish and the plants exposed to NP contamination, the amount of Ti was higher than in the control, indicating an effective bioaccumulation of NPs or ions originating from NPs. It was clearly shown that the NPs present in the sediments are available to plants and fish. Additionally, the aquatic plants, an important trophic level in the food chain, can accumulate NPs and be a source of NPs for higher organisms. It was concluded that even an incidental contamination of water by NPs may result in long-term consequences induced by the release of NPs.     

Tibial plateau symmetry and the effect of osteophytosis on tibial plateau angle measurements

A novel technique was developed to estimate the caudal medial tibial plateau landmark in the face of osteophytosis to improve accuracy in tibial plateau angle measurements. Using this technique, tibial plateau angles were evaluated in 31 normal dogs before and 8 months after right cranial cruciate ligament transection. There was no significant difference in mean tibial plateau angle before or after induction of osteophytosis. Additionally, it was determined that 90% of dogs had a difference of =2 degrees between right and left tibial plateau angles, which was considered symmetrical.     

Modelling wood formation and structure: power and limits of a morphogenetic gradient in controlling xylem cell proliferation and growth

Key message

The emergence of the characteristic tree-ring pattern during xylogenesis is commonly thought to be controlled by a gradient of morphogen (auxin, TDIF peptide...). We show that this hypothesis accounts for several developmental aspects of wood formation, but not for the final anatomical structure.

Context

Wood formation is a dynamic cellular process displaying three generic features: (i) meristematic cell proliferation is restricted to the small cambial zone, preventing exponential xylem radial growth along the growing season; (ii) developmental processes result in a stable zonation of the developing xylem; (iii) the resulting mature wood cells form the typical tree-ring structure made of early and late wood with a gradient of cell sizes, an important trait for wood functioning in trees and for lumber quality. The mechanisms producing these spatial-temporal patterns remain largely unknown. According to the often-cited morphogenetic-gradient hypothesis, a graded concentration profile of a signalling molecule (e.g. auxin, TDIF) controls xylogenesis by providing positional information to differentiating cells.

Aims

We assessed the predictions of the morphogenetic-gradient theory.

Methods

We developed a computational model of wood formation implementing hypotheses on how a morphogen flows through the developing xylem and controls cell division and growth and we tested it against data produced by studies monitoring wood formation in conifers.

Results

We demonstrated that a morphogenetic gradient could indeed control xylem radial growth and wood-forming tissue zonation. However, it failed to explain the pattern of final cell sizes observed in tree-rings. We discussed the features that candidate additional regulatory mechanisms should meet.

     

Measured and estimated water use and crop coefficients of grapevines trained to overhead trellis systems in California’s San Joaquin Valley

The use of overhead trellis systems for the production of dry-on-vine (DOV) raisins and table grapes in California is expanding. Studies were conducted from 2006 to 2009 using Thompson Seedless grapevines grown in a weighing lysimeter trained to an overhead arbor trellis and farmed as DOV raisins for the first two years and for use as table grapes thereafter. Maximum canopy coverage for the two lysimeter vines across years was in excess of 80 %. Seasonal (15 March–31 October) evapotranspiration for the lysimeter vines (ET_Lys) was 952 mm in 2007 (farmed as DOV raisins) and 943 and 952 mm (when farmed as table grapes). The maximum crop coefficient (K _cLys) across all 4 years ranged from 1.3 to 1.4. These maximum values were similar to those estimated using the relationship where K _c is a function of the amount of shaded area measured beneath the canopy at solar noon (K _c = 0.017 × percent shaded area). Covering the lysimeter’s soil surface with plastic (and then removing it) numerous times during the 2009 growing season (1 June–14 September) reduced ET_Lys from an average of 6.4 to 5.6 mm day^?1 and the K _c from 1.07 to 0.93. A seasonal basal K _c (K _cb) was calculated for grapevines using an overhead trellis system with a 13 % reduction in the K _cLys across the growing season.     

The effect of low level laser therapy (LLLT) on wound healing in horses.

Laser therapy is used in many countries, including South Africa, for the treatment of skin wounds. Low level galium aluminium arsenide (GaAlAs) laser was administered to full thickness skin wounds (3 x 3 cm) induced surgically on the dorsal aspect of the metacarpophalangeal joints of 6 crossbred horses in a randomised, blind, controlled study. Treated wounds that received a daily laser dosage of 2 J/cm2 were compared with nontreated control wounds on the opposite leg. There were no wound complications. Both groups of wounds were cleaned daily using tap water. Wound contraction and epithelialisation were evaluated using photoplanimetry. There were no significant differences in wound contraction or epithelialisation between the laser treated and the control wounds. It was therefore concluded that laser therapy had no clinically significant effect on second intention wound healing in this study.     

N<Subscript>2</Subscript>-fixation along a gradient of long-term disturbance in tropical mangroves bordering the gulf of Mexico

Microbial processes are key elements in determining the productivity of mangroves, and reductions in these processes reflect the loss of microbial biodiversity and function due to fabricated disturbances. Because nitrogen is a major limiting nutrient for the productivity of these ecosystems, the goal of this study was to determine profiles of inorganic nitrogen combined with several environmental parameters, all in relation to the degree of long-term hydraulic impairment of a tropical, monospecific black mangrove (Avicennia germinans) forest that showed degradation ranging from total loss of mangrove cover to no disturbance. N₂-fixation, oxygen levels, and nitrite contents decreased significantly with the severity of the disturbance, and almost null levels were reached in the completely degraded zone, whereas salinity achieved very high values. Concomitantly, total N, ammonium, and P contents and ammonia volatilization increased significantly. Pore-water temperature and pH increased moderately. Other soil physical properties (sand, silt, clay, organic matter, and total C), which varied among the sampling sites, were not correlated with the level of disturbance. Principal component analyses, including environmental and biological parameters, suggested that the most significant finding was the considerable loss of N₂-fixation with increasing impairment, which was concomitant with significant increases in volatilization of ammonia and salinity. The results show that microbial N-cycling processes are highly sensitive to salinity and to man-made disturbances that modify the water level and flow.     

Phenytoin as a novel anti-vitiligo weapon

Vitiligo is a psychologically devastating clinical conundrum which affects approximately 1% of the general population. The exact cause of the illness is an enigma, but several hypotheses about its pathogenesis are advanced.The autoimmune hypothesis proposes an autoimmune attack against melanocytes. Although anti-melanocyte autoantibodies have been demonstrated in vitiligo, recent research casts doubt on their pathogenic role and instead supports the involvement of cell-mediated autoimmune response in the pathobiology of this disorder, which is characterized by increase of suppressor T-cells and decrease of the helper/suppressor ratio in association with the presence of type-1 cytokine secreting cytotoxic T cells in the vicinity of disappearing melanocytes.The neural hypothesis proposes that increased release of norepinephrine, a melanocytotoxin, from the autonomic nerve endings in the microenvironment of melanocytes injures these cells. Moreover, norepinephrine induces the catecholamine degrading enzyme monoamine oxidase (MAO), which favors the formation of toxic levels of hydrogen peroxide in the vicinity of melanocytes.Another theory suggests that abnormal permeability of melanosome membrane, which normally prevents the diffusion of toxic melanin precursors into the cytoplasm, may cause melanocyte damage.Phenytoin, the widely-used anticonvulsant, has been employed both topically and systemically in the treatment of some dermatological disorders. The drug has been shown to significantly suppress mitogen-induced activation of lymphocytes and cytotoxic T lymphocyte activity and to polarize the immune response toward the type-2 pathway. It also significantly decreases suppressor T cells and increases the helper/suppressor ratio.At high concentrations, the drug inhibits the release of norepinephrine and the activity of MAO. Moreover, phenytoin is suggested to interact with membrane lipids, which may promote stabilization of the membranes.The hydantoin moiety of phenytoin exerts a direct stimulatory action on melanocytes; facial hyperpigmentation is a recognized side effect of orally administered phenytoin.Altogether, the above evidence suggests that phenytoin could be therapeutically effective against vitiligo. As phenytoin stimulates collagen production and inhibits its breakdown, its concomitant use with topical steroids could prevent steroid-induced skin atrophy while potentiating the anti-vitiligo effect of these agents.     

Identification,potential inoculum sources and pathogenicity of botryosphaeriaceous species associated with grapevine dieback disease in New Zealand

This study investigated the prevalence and identity of botryosphaeriaceous dieback pathogens in necrotic grapevines tissues in New Zealand vineyards, and other woody hosts growing nearby. The presumptive identities of the isolates by conidial and cultural morphology were confirmed with ITS sequence data as Neofusicoccum australe, N. luteum, N. parvum and Diplodia seriata. They were isolated predominantly from necrotic stems of grapevine and other hosts, but also from leaves, flowers and wood debris of grapevines. Inoculation with conidia and mycelium of multiple isolates of each species onto excised and attached green shoots and trunks of five grapevine varieties, Cabernet sauvignon, Chardonnay, Pinot noir, Riesling, and Sauvignon blanc, showed that all varieties became infected to a similar extent. All species except D. seriata were pathogenic, irrespective of the host source, with N. luteum being the most and D. mutila the least pathogenic (P < 0.05). On trunks, N. parvum caused cankers and the other pathogenic species caused die-back when the inoculated vines became winter-dormant. Conidia were produced from green shoot lesions and die-back wood, which indicates potential inoculum sources for vineyard infection.