Treesearch

Sex ratio theory attempts to explain observed variation in offspring sex ratio at both the population and the brood levels. In the context of low-fecundity organisms producing high-investment offspring, the drivers of adaptive variation in sex ratio are incompletely understood. For raptors that display reverse sexual dimorphism (RSD), preferential allocation of resources to the putatively cheaper sex (male) may be a response to environmental, social or demographic stressors. To assess the extent of skew in offspring sex ratios and to evaluate possible dietary, environmental and demographic...

Rapid quantitative laboratory test methods are needed to screen potential antifungal agents. Existing laboratory test methods are relatively time consuming, may require specialized test equipment and rely on subjective visual ratings. A quantitative, colorimetric micro-assay has been developed that uses XTT tetrazolium salt to metabolically assess mold spore germination. Using isothiazolinone as a model mold inhibitor, the minimum inhibitory concentration (MIC) for the XTT assay was compared with the 4 week ASTM plate method (D4445) to test fungicides for controlling mold and the 8 week...

Protein adhesives allowed the development of bonded wood products such as plywood and glulam in the early 20th century. Petrochemical-based adhesives replaced proteins in most wood bonding applications because of lower cost, improved production efficiencies, and enhanced durability. However, several technological and environmental factors have led to a resurgence of proteins, especially soy flour, as an important adhesive for interior nonstructural wood products. This paper discusses important aspects of protein structure and recent successful advances in higher performance soy flour...

The prime objective of this investigation was to compare mass loss from termite attack on NHA treated and untreated pine blocks simultaneously in a two-block choice test using Reticulitermes flavipes (Kollar). Southern pine blocks were vacuum treated with aqueous solutions of NHA ranging from 250-10,000 ppm and exposed to one gram of R. flavipes workers in the dual block choice test which included one treated and one untreated block per the modified AWPA laboratory test (E1-09). At the end of four weeks, all test blocks were removed, weighed and the mass losses statistically modeled using...

Covered bridges can be vulnerable to damage from fungal decay and insect attack. This paper describes procedures for selecting and applying in-place treatments to prevent or arrest biodegradation, and summarizes recent research evaluating some of these treatments. Wood moisture is the key to decay and termite attack, and the first line of defense against biodeterioration is to minimize moisture intrusion through prompt maintenance and repair. Biodeterioration will tend to be more prevalent wherever members contact abutments, are near the ends of bridges subject to wetting from splashing,...

Ordinal rating systems are commonly employed to evaluate biodeterioration of wood exposed outdoors over long periods of time. The purpose of these ratings is to compare the durability of test systems to nondurable wood products or known durable wood products. There are many reasons why these systems have evolved as the chosen method of evaluation, including having an overall evaluation that incorporates several characteristics thought to correlate with some “failure,” balancing bias and variability because of multiple raters and simplifying calculation and interpretation. Appropriate...

Estimates of service life are increasingly used to compare life cycle costs of building materials. Because of a lack of published data for treated wood, some users assume a relatively low service life for wood in comparison to alternative materials. Such bias against durable wood products may cause alternative materials to appear more economical. This paper discusses options for making additional treated wood service life information available to engineers and others who are comparing construction materials. In the short term, existing data and reports could be summarized and published in...

The reinforcement potential of novel nanocellulose-based scaffolding reinforcements composed of microfibrils 5 to 50 nm in diameter and several microns in length was investigated. The cellulose nanofibril reinforcement was used to produce a three-dimensional scaffolding. A hybrid two-step approach using vacuum pressure and hot pressing was used to integrate the nanocellulose reinforcements in a liquid molding process with an epoxy resin to manufacture composites containing fiber volume contents ranging from 0.6% to 7.5%. The mechanical properties were studied using three-point bending. The...

We report on efficient solar cells on recyclable cellulose nanocrystal (CNC) substrates with a new device structure wherein polyethylenimine-modified Ag is used as the bottom electron-collecting electrode and high-conductivity poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate) (PEDOT:PSS, PH1000) is used as the semitransparent top holecollecting electrode. The PEDOT:PSS top electrode is deposited by a film-transfer lamination technique. This dry process avoids swelling damage to the CNC substrate, which is observed when PEDOT:PSS is directly spin-coated from an aqueous solution....

We georeferenced Western Pond Turtle (Actinemys marmorata) and Painted Turtle (Chrysemys picta) locality records in western North America, compiling diverse institutional data sets, including data from 9 US states and Canadian provinces. For the entire range of the Western Pond Turtle and the western range of the Painted Turtle, we assessed counts of distinct locations from historical data, and analyzed distribution patterns temporally and spatially. Western Pond Turtle observation records were compiled from year 1850 to 2011, and Painted Turtle records were compiled from 1805 to 2011. For...