Improved Durability of Wood Treated with Nano Metal Fluorides against Brown-Rot and White-Rot Fungi

Low-water soluble metal fluorides such as magnesium fluoride (MgF2) and calcium fluoride (CaF2) were evaluated for decay protection of wood. Initially, the biocidal efficacy of nano metal fluorides (NMFs) against wood destroying fungi was assessed with an in-vitro agar test. The results from the test showed that agar medium containing MgF2 and CaF2 was more efficient in preventing fungal decay than stand-alone MgF2 or CaF2. These metal fluorides, in their nanoscopic form synthesized using fluorolytic sol-gel synthesis, were introduced into the sapwood of Scots pine and beech wood and then subjected to accelerated ageing by leaching (EN 84). MAS 19F NMR and X-ray micro CT images showed that metal fluorides were present in treated wood, unleached and leached. Decay resistance of Scots pine and beech wood treated with NMFs was tested against wood destroying fungi Rhodonia placenta and Trametes versicolor in accordance with EN 113. Results revealed that mass losses were reduced to below 3% in wood treated with the combination of MgF2 and CaF2. It is concluded that NMFs provide full protection to wood even after it has been leached and can be used as wood preservatives in outdoor environments.Peer Reviewe

Finishing the euchromatic sequence of the human genome

The sequence of the human genome encodes the genetic instructions for human physiology, as well as rich information about human evolution. In 2001, the International Human Genome Sequencing Consortium reported a draft sequence of the euchromatic portion of the human genome. Since then, the international collaboration has worked to convert this draft into a genome sequence with high accuracy and nearly complete coverage. Here, we report the result of this finishing process. The current genome sequence (Build 35) contains 2.85 billion nucleotides interrupted by only 341 gaps. It covers ∼99% of the euchromatic genome and is accurate to an error rate of ∼1 event per 100,000 bases. Many of the remaining euchromatic gaps are associated with segmental duplications and will require focused work with new methods. The near-complete sequence, the first for a vertebrate, greatly improves the precision of biological analyses of the human genome including studies of gene number, birth and death. Notably, the human enome seems to encode only 20,000-25,000 protein-coding genes. The genome sequence reported here should serve as a firm foundation for biomedical research in the decades ahead

Termite resistance of pine wood treated with nano metal fluorides

Fluorides are well-known as wood preservatives. One of the limitations of fluoride-based wood preservatives is their high leachability. Alternative to current fluoride salts such as NaF used in wood protection are low water-soluble fluorides. However, impregnation of low water-soluble fluorides into wood poses a challenge. To address this challenge, low water-soluble fluorides like calcium fluoride (CaF2) and magnesium fluoride (MgF2) were synthesized as nanoparticles via the fluorolytic sol−gel synthesis and then impregnated into wood specimens. In this study, the toxicity of nano metal fluorides was assessed by termite mortality, mass loss and visual analysis of treated specimens after eight weeks of exposure to termites, Coptotermes formosanus. Nano metal fluorides with sol concentrations of 0.5 M and higher were found to be effective against termites resulting in 100% termite mortality and significantly inhibited termite feeding. Among the formulations tested, the least damage was found for specimens treated with combinations of CaF2 and MgF2 with an average mass loss less than 1% and visual rating of “1”. These results demonstrate the efficacy of low water-soluble nano metal fluorides to protect wood from termite attack.Peer Reviewe

Nano Metal Fluorides for Wood Protection against Fungi

Wood treated with nano metal fluorides is found to resist fungal decay. Sol–gel synthesis was used to synthesize MgF₂ and CaF₂ nanoparticles. Electron microscopy images confirmed the localization of MgF₂ and CaF₂ nanoparticles in wood. Efficacy of nano metal fluoride-treated wood was tested against brown-rot fungi <i>Coniophora puteana</i> and <i>Rhodonia placenta</i>. Untreated wood specimens had higher mass losses (∼30%) compared to treated specimens, which had average mass loss of 2% against <i>C. puteana</i> and 14% against <i>R. placenta</i>, respectively. Nano metal fluorides provide a viable alternative to current wood preservatives

Direct Synthesis of Anatase Films with ∼100% (001) Facets and [001] Preferred Orientation

Anatase films exhibiting ∼100% (001) reactive facets at the surface were grown hydrothermally on gold substrate from a homogeneous solution of TiF₄ and NaF. In addition to NaF, it was found that TiO₂ films with very similar properties could be prepared with the fluoride salts LiF, CsF, HF, NH₄F, and N­(CH₂CH₃)₄F. The polycrystalline anatase films are continuous, approximately 1 μm thick, and evenly coat the substrate. The surface grain size is ∼400 nm. Grazing angle XRD measurements show that the films exhibit a high degree of preferred orientation with the <i>c</i>-axis normal to the substrate surface. SEM images reveal that the grains span the thickness of the films. Annealing the films at 500 °C removes fluorine and causes crystallites within the grains to restructure as shown by SEM, XRD, and Raman spectroscopy. Supported anatase films grown from this one-pot method may serve as oxidative photocatalysts and electrodes for photoelectrochemical applications such as solar cells and hydrogen evolution

Location of Hole and Electron Traps on Nanocrystalline Anatase TiO₂

The defect photoluminescence from TiO₂ nanoparticles in the anatase phase is reported for nanosheets which expose predominantly (001) surfaces and compared to that from conventional anatase nanoparticles which expose mostly (101) surfaces. Also reported is the weak defect photoluminescence of TiO₂ nanotubes, which we find using electron backscattered diffraction to consist of walls which expose (110) and (100) facets. The nanotubes exhibit photoluminescence that is blue-shifted and much weaker than that from conventional TiO₂ nanoparticles. Despite the preponderance of (001) surfaces in the nanosheet samples, they exhibit photoluminescence similar to that of conventional nanoparticles. We assign the broad visible photoluminescence of anatase nanoparticles to two overlapping distributions: hole trap emission associated with oxygen vacancies on (101) exposed surfaces, which peaks in the green, and a broader emission extending into the red which results from electron traps on undercoordinated titanium atoms, which are prevalent on (001) facets. The results of this study suggest how morphology of TiO₂ nanoparticles could be optimized to control the distribution and activity of surface traps. Our results also shed light on the mechanism by which the TiCl₄ surface treatment heals traps on anatase and mixed-phase TiO₂ films and reveals distinct differences in the trap-state distributions of TiO₂ nanoparticles and nanotubes. The molecular basis for electron and hole traps and their spatial separation on different facets is discussed