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The reversible, stepwise formation of individual Nb−µ-O−Nb linkages during acid condensation of 2 equiv of A-[alpha]-[SiNb3W9O40]7- (1) to the tri-µ-oxo-bridged structure A-[alpha]-[Si2Nb6W18O77]8- (4) is demonstrated by a combination of X-ray crystallography and variable-pD solution 183W and 29Si NMR spectroscopy. Addition of DCl to a pD 8.4 solution of 1 (Li+ salt in D2O) results in formation of a mono-Nb−µ-O−Nb-linked dimer, A-[alpha]-[Si2Nb6W18O79]12- (2; pD = 3.0−1.3). At pD values between 1.6 and 0.3, two isomers (syn and anti) of the di-µ-oxo-bridged dimer, A-[alpha]-[Si2Nb6W18O78]10...

In a laboratory leaching study, we found that chromated copper arsenate (CCA) treated wood, which had been exposed to one of five soils examined, unexpectedly appeared to gain significant Cr (47%) when measured with an energy-dispersive x-ray fluorescence instrument (American Wood-Preservers' Association (AWPA) Method A9-01 2001). Analysis of some of the leached samples exposed to all five soils by inductively coupled plasma (ICP) spectrometry showed that Fe migrated into the CCA-treated samples from four of the five soils and Mn migrated into wood exposed to two of the five soils. The...

Some engineered wood fiber surfaces are uneven, tend to shift, and have low density. The goal of our research was to develop a playground surface material that cushions impact and is accessible to people with disabilities. In the initial screening phase, we evaluated a variety of in situ surface treatments and mixtures of wood particles combined with various binders. Engineered wood fiber (EWF) was prepared from three species, red maple, ponderosa pine, and one-seed juniper, which have a wide range of densities and bonding properties. In the scale-up phase, we evaluated commercially...

Pulping technologies can be synthesized with fiber loading with simultaneous alkaline peroxide bleaching to produce lightweight high-opacity printing papers. We compared the results of recent experiments on combining oxalic acid pretreated wood chips used for thermomechanical pulp (TMP) with fiber loading and previous experiments on combining similar pulps treated with fungal and microwave pretreatments with fiber loading. For TMP at 100 mL CSF, various species and pretreatments resulted in differences in (a) energy requirements for pulp production, (b) properties of handsheets prepared...

The release of arsenic from wood pressure-treated with chromated copper arsenate (CCA) can be decreased by application of wood finishes, but little is known about the types of finishes that are best suited for this purpose. This study evaluated the effects of finish water repellent content and ultraviolet (UV) radiation on the release of arsenic, copper, and chromium from CCA-treated wood exposed to simulated rainfall. Deck boards treated with CCA were either left unfinished or dipped in a finish prepared with 1%, 3%, or 5% water repellent. All specimens were exposed to leaching from...

To prevent the unintentional transfer of insects and pathogens during world trade, wood products are often heat sterilized. The general requirement is that the center of the wood configuration be held at 133°F (56°C) for 30 min. However, many factors can affect the time required to reach this temperature. This study explored several of these factors, including thickness of boards or cross-sectional dimension of square timbers, wet-bulb depression, and stacking method (solid or stickered). The heating temperature used was 160°F (71°C). Heating time increased with increasing board thickness...

Four new species of corticioid fungi from Hawaii are described and illustrated. The new genus Hemmesomyces is described to accommodate the new species H. puauluensis. Radulomyces tantalusensis, Crustoderma fuscatum and Scopuloides magnacystidiata also are described as new. In addition, the new combination Crustoderma vulcanense is proposed. Keys to the species of Crustoderma, Radulomyces and Scopuloides are provided.

As of December 31, 2000, there were 603 buildings at Naval Station (NAVSTA) Norfolk with a combined floor area of nearly 17.3 million ft2. In one-third of these buildings, structural wood products were used in one or more major structural building applications, utilizing an estimated 11.6 million board feet of lumber, 0.4 million ft2 (3/8-in. basis) of structural panels, and 0.1 million ft2 (3/8-in. basis) of fiberboard. Wood buildings, on average, were about 40% smaller than their nonwood counterparts. They were also older. Half of all the buildings and three-fourths of all wood buildings...

Improving the exterior quality bonding of wood to epoxy adhesive resins is important for bonding glass-fiber-reinforced vinyl ester resin laminae to glulam structural members, as well as for repairing glulam members in exterior applications on site. The coupling agent for these applications, hydroxymethylated resorcinol (HMR), was recently improved by using a novolak version (n-HMR) to reduce reaction time. In this study, the chemical composition of HMR was changed to decrease the total amount of formaldehyde added to the system. The results showed that n-HMR can be applied to a wood...

In this study, a cellulose-fiber-reinforced Polyamide-6 (PA-6) composite, a hybrid composite (PA-6/cellulose/Wollastonite), and the neat PA-6 resin were injection molded into ASTM test–bar samples with conventional and microcellular injection molding. The impact and tensile strengths of molded samples were measured and the Scanning Electron Microscopy (SEM) images were taken at the fracture surfaces. The effects of filler systems and the introduction of microcellular structure on the impact and tensile strengths were studied. It was found that the cellulose fibers and the cellulose/Wollasto...