Forensic Microscope
Welcome to Forensic MicroscopeWithin-tree and between-tree variation of wood density components in cork oak trees in two sites in Portugal
Within-tree and between-tree variation of wood density components in cork oak trees in two sites in Portugal
 |
 |
 |
The axial and radial variation of wood density was studied using microdensitometry in cork oaks (Quercus suber) in two sites in Portugal. The observations were made in mature trees under cork production and in juvenile trees before the first cork extraction, at three height levels (stem base, 1.3 m and before stem bifurcation). The cork oak wood revealed a very high mean density (0.884–1.068 g cm–3). Differences between earlywood and latewood were small (0.866 and 1.061 g cm–3, respectively). Latewood corresponded on average to 61 per cent of the total. The variation of density between trees was statistically highly significant, but no differences were found between the two sites. The within-tree axial variation was negligible but the radial direction within a cross-section was one of the main origins of variation of the density components (18 per cent of the total variation). The density decreased from pith to cambium and this radial variation corresponded to 19–24 per cent of the total variation of wood density. Overall, the magnitude of density variations between and within cork oaks was small and an advantageous factor for their use for quality wood products.
Click Here to read the entire article...
Other Articles:
| • | University of Colorado Awarded Patent Licensed to ALD NanoSolutions, Inc. |
| The University of Colorado has been awarded U.S. Patent number 7,426,067 'Atomic layer deposition on micro-mechanical devices,' which has been exclusively licensed to ALD NanoSolutions, Inc. | |
| Click Here to read the entire article... |
|
| • | Water Transport in Resin-modified Glass-ionomer Dental Cement |
Water uptake and water loss have been studied in a commercial resin-modified glass-ionomer cement, Fuji II LC, under a variety of conditions. Uptake was generally non-Fickian, but affected by temperature. At room temperature, the equilibrium water uptake values varied from 2.47 to 2.78% whereas at low temperature (12°C), it varied from 0.85 to 1.18%. Cure time affected uptake values significantly. Water uptake was much lower than in conventional glass-ionomer restorative cements exposed to water vapor. Loss of water under desiccating conditions was found to be Fickian for the first 5 h loss at both 22 and 12°C. Diffusion coefficients were between 0.45 and 0.76 x 10 -7 cm2/s, with low temperature diffusion coefficients slightly greater than those at room temperature. Plotting water loss as percentage versus s-1/2 allowed activation energies to be determined from the Arrhenius equation and these were found to be 65.6, 79.8, and 7.7 kJ/mol respectively for 30, 20, and 10 s cure times. The overall conclusion is that the main advantage of incorporating HEMA into resin-modified-glass-ionomers is to alter water loss behavior. Rate of water loss and total amount lost are both reduced. Hence, resin-modified glass-ionomers are less sensitive to water loss than conventional glass-ionomers. |
|
| Click Here to read the entire article... |
|
| • | Pomology: Fruit Cultivation and Production |
| Provides links to websites and research articles in the applied life science pomology. The site focusses on the numerous scientific and commercial aspects of the cultivation and production of temperate, subtropical and tropical fruits. | |
| Click Here to read the entire article... |
|
| • | Pavement Sealcoat Linked To Urban Lake Contamination In The Central And Eastern United States |
| Dust collected from coal-tar sealcoated parking lots in Central and Eastern U.S. cities contains concentrations of polycyclic aromatic hydrocarbons (PAHs) that are about 1,000 times greater than levels found in Western cities where coal-tar sealcoat is less commonly used, according to a new study. |
|
| Click Here to read the entire article... |
|
| • | Introduction to bleeding |
| Identifying if it is a minor or severe wound | |
| Click Here to read the entire article... |
|
| • | Development and optimization of an internally controlled dried blood spot assay for surveillance of human immunodeficiency virus type-1 drug resistance |
|
We present the evaluation of a methodology for the genotypic assessment of human immunodeficiency virus type-1 (HIV-1) drug resistance, optimized for use with dried blood spots (DBS). The ability to generate HIV-1 protease (PR) and reverse transcriptase (RT) contiguous amplicons and nucleotide sequences from DBS was evaluated. Different collection matrices and extraction methodologies were compared. The relative subtype sensitivity of the amplification strategy was assessed using a comprehensive panel of plasmids representing A–H subtypes. A panel of DBS and plasma specimens was subjected to HIV genotyping. Sequences generated from each sample type were compared. Extensive replicate testing revealed most sensitivity with the use of 903 filter paper and silica/guanidine extraction, which had an estimated 95% inclusivity endpoint of 1542 proviral copies/mL, as compared with 21 573 proviral copies/mL for the FTA system. All HIV-1 group M subtypes analysed—with the exception of subtypes A2, AE, AG, F and H—had a relative sensitivity of ≤10 plasmid copies/PCR reaction. The PCR was multiplexed to include amplification of a human housekeeping gene to monitor the integrity of the human genomic DNA. Using a panel of clinical samples, we demonstrated the ability to amplify and sequence from 83% (n = 10) in the PR region and 100% (n = 12) in the RT region, of samples with detectable viral load. All specimens with an HIV-1 RNA load ≥1000 copies/mL were successfully amplified and sequenced. Twelve specimens had pol genotyping from both plasma and DBS samples. Sequence analysis and drug resistance interpretation revealed that 10 (83%) provided concordant drug resistance interpretation. Our results demonstrate that the technique is appropriate for surveillance of drug resistance in untreated individuals and those with virological failure on therapy. |
|
| Click Here to read the entire article... |
|
By michael@nanowerk.com (Michael Berger) - Copyright 2005-2008 Nanowerk LLC - version: v1.5 build A