Xi Sigma Pi

Xi Sigma Pi, founded in 1908 at the University of Washington, is the National Forestry Honor Society. The Alpha Gamma chapter was chartered at Iowa State in 1965. Our local chapter conducts member initiation, sponsors service projects, and gives scholarships and awards

Microscopy Of Progressive Decay Of Cottonwood By The Brown-Rot Fungus Gloeophyllum Trabeum

Eastern cottonwood (Populus deltoides Bartr.) samples subjected to various degrees of brown-rot decay by Gloeophyllum trabeum (FPL 617) were studied by scanning electron (SEM) and polarizing microscopy. A technique was developed to prepare decayed wood specimens for SEM. Ray cells were heavily decomposed in early stages of decay. Bore holes were produced in early stages to facilitate hyphal penetration into fiber tracheids. Degradation of fiber tracheid walls began with the formation of radial checks or voids in the S2 layer, followed by the removal of the entire S2 layer, which often caused the separation of the S3 layer from the remaining cell wall. The S3 layer often was removed before the decomposition of the S1 layer. The compound middle lamella remained intact even after the complete removal of the secondary wall

Impacts of Forest Management Activities on Selected Hardwood Wood Quality Attributes: A Review

Hardwoods are increasingly being viewed as an important raw material component of the forest products industry, and this has spurred awareness of the impact of forest management on tree and wood quality. The impacts of various forest management activities on tree and wood quality in hardwoods are presented from the standpoint of the activities themselves rather than that of the wood properties. These silvicultural activities include genetic manipulation, intensive culture, fertilization and/or irrigation, pruning, thinning, weed control, and prescribed fire. A broad literature cited section is included as an aid to future scientists

Physical Properties of Kraft PULP From Four-Year-Old Aspen Hybrids and Crosses

Short-rotation forestry and species hybridization offer acceptable raw materials for pulp and paper production. Poplars (Populus spc.) are the most promising materials because of their fast growth rates and their suitability for pulp. The objectives of this study were to determine the kraft pulp properties of three new aspen hybrids and crosses and to compare these properties with those of other poplars. We used Populus alba X Populus tremula, Populus alba X Populus alba Bolleana, and Populus alba X Populus grandidentata. Results indicated that the P. alba X P. trernula hybrid was most suitable for pulp production. Handsheets made from the P. alba X P. tremula hybrid had greater burst and tear strengths and a comparable tensile index compared with those of the kraft pulps of other juvenile poplars. Results suggest that P. alba X P. tremula is a promising hybrid for pulp production

Repression of Lignin Biosynthesis Promotes Cellulose Accumulation and Growth in Transgenic Trees

Because lignin limits the use of wood for fiber, chemical, and energy production, strategies for its downregulation are of considerable interest. We have produced transgenic aspen (Populus tremuloidesMichx.) trees in which expression of a lignin biosynthetic pathway genePt4CL1 encoding 4-coumarate:coenzyme A ligase (4CL) has been downregulated by antisense inhibition. Trees with suppressed Pt4CL1expression exhibited up to a 45% reduction of lignin, but this was compensated for by a 15% increase in cellulose. As a result, the total lignin–cellulose mass remained essentially unchanged. Leaf, root, and stem growth were substantially enhanced, and structural integrity was maintained both at the cellular and whole-plant levels in the transgenic lines. Our results indicate that lignin and cellulose deposition could be regulated in a compensatory fashion, which may contribute to metabolic flexibility and a growth advantage to sustain the long-term structural integrity of woody perennials

International Nonregimes: A Research Agenda1

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/146934/1/j.1468-2486.2007.00672.x.pd

Identification of genetic variants associated with Huntington's disease progression: a genome-wide association study

Background Huntington's disease is caused by a CAG repeat expansion in the huntingtin gene, HTT. Age at onset has been used as a quantitative phenotype in genetic analysis looking for Huntington's disease modifiers, but is hard to define and not always available. Therefore, we aimed to generate a novel measure of disease progression and to identify genetic markers associated with this progression measure. Methods We generated a progression score on the basis of principal component analysis of prospectively acquired longitudinal changes in motor, cognitive, and imaging measures in the 218 indivduals in the TRACK-HD cohort of Huntington's disease gene mutation carriers (data collected 2008–11). We generated a parallel progression score using data from 1773 previously genotyped participants from the European Huntington's Disease Network REGISTRY study of Huntington's disease mutation carriers (data collected 2003–13). We did a genome-wide association analyses in terms of progression for 216 TRACK-HD participants and 1773 REGISTRY participants, then a meta-analysis of these results was undertaken. Findings Longitudinal motor, cognitive, and imaging scores were correlated with each other in TRACK-HD participants, justifying use of a single, cross-domain measure of disease progression in both studies. The TRACK-HD and REGISTRY progression measures were correlated with each other (r=0·674), and with age at onset (TRACK-HD, r=0·315; REGISTRY, r=0·234). The meta-analysis of progression in TRACK-HD and REGISTRY gave a genome-wide significant signal (p=1·12 × 10−10) on chromosome 5 spanning three genes: MSH3, DHFR, and MTRNR2L2. The genes in this locus were associated with progression in TRACK-HD (MSH3 p=2·94 × 10−8 DHFR p=8·37 × 10−7 MTRNR2L2 p=2·15 × 10−9) and to a lesser extent in REGISTRY (MSH3 p=9·36 × 10−4 DHFR p=8·45 × 10−4 MTRNR2L2 p=1·20 × 10−3). The lead single nucleotide polymorphism (SNP) in TRACK-HD (rs557874766) was genome-wide significant in the meta-analysis (p=1·58 × 10−8), and encodes an aminoacid change (Pro67Ala) in MSH3. In TRACK-HD, each copy of the minor allele at this SNP was associated with a 0·4 units per year (95% CI 0·16–0·66) reduction in the rate of change of the Unified Huntington's Disease Rating Scale (UHDRS) Total Motor Score, and a reduction of 0·12 units per year (95% CI 0·06–0·18) in the rate of change of UHDRS Total Functional Capacity score. These associations remained significant after adjusting for age of onset. Interpretation The multidomain progression measure in TRACK-HD was associated with a functional variant that was genome-wide significant in our meta-analysis. The association in only 216 participants implies that the progression measure is a sensitive reflection of disease burden, that the effect size at this locus is large, or both. Knockout of Msh3 reduces somatic expansion in Huntington's disease mouse models, suggesting this mechanism as an area for future therapeutic investigation

Variation In Cell Dimensions and Fibril Angle For Two Fertilized Even-Aged Loblolly Pine Plantations

Increment core samples were obtained from randomly selected, nine-year-old loblolly pine (Pinus taeda L.) in two even-aged plantations in Louisiana in order to determine the variation in cell dimensions and fibril angle of the sites. The Homer site is representative of the growing conditions in north Louisiana, and the Bogalusa site is typical of the conditions in southeastern Louisiana. Both sites were subjected to similar site preparation and weed control and were fertilized in the juvenile period. The anatomical properties that were measured include: fiber length, cell-wall thickness, and microfibril angle (MFA). Observations were made in order to compare corewood (rings 2-4) and outerwood (rings 7-9) and also between earlywood and latewood. For both plantations, the statistical analysis revealed that cell-wall thickness and fiber length were significantly greater in outerwood and latewood than in corewood and earlywood, respectively. Microfibril angle was found to be significantly higher in corewood than in outerwood for both plantations. The anatomical properties were found to be more acceptable from an end-use perspective on the Homer site, which experienced slower diameter growth than the Bogalusa site

A case study of fluidized-bed combustion of wood/coal mixtures. Part B. The effect of wood moisture content

A bubbling fluidized-bed combustor was used to cofire wood and coal fuels. Wood percentages in the fuel mixture were varied from 0 to 100 percent as the effect of two different wood moisture contents (8.3 and 50% on a dry weight basis) was studied on the emissions of sulfur and nitrogen. The variation in wood moisture content did not appear to be a factor in any reduction in the SO 2 emissions for wood/coal cofiring. Increased wood moisture only slightly diminished the emissions of oxides of nitrogen. Combustion results were similar to previous cofiring results with dry planer shavings