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Nm Long (nm + long)
Selected AbstractsEarliest fossil record of bacterial,cyanobacterial mat consortia: the early Silurian Passage Creek biota (440 Ma, Virginia, USA)GEOBIOLOGY, Issue 2 2008A. M. F. TOMESCU ABSTRACT Cyanobacteria in terrestrial and aquatic habitats are frequently associated with heterotrophic bacteria, and such associations are most often metabolically interactive. Functionally, the members of such bacterial,cyanobacterial consortia benefit from diverse metabolic capabilities of their associates, thus exceeding the sum of their parts. Such associations may have been just as ubiquitous in the past, but the fossil record has not produced any direct evidence for such associations to date. In this paper, we document fossil bacteria associated with a macrophytic cyanobacterial mat in the early Silurian (Llandovery) Massanutten Sandstone of Virginia, USA. Both the bacterial and the cyanobacterial cells are preserved by mineral replacement (pyrite subsequently replaced by iron oxyhydroxides) within an amorphous carbonaceous matrix which represents the common exopolysaccharide investment of the cyanobacterial colony. The bacteria are rod-shaped, over 370 nm long and 100 nm in diameter, and occur both as isolated cells and as short filaments. This occurrence represents the oldest fossil evidence for bacterial,cyanobacterial associations, documenting that such consortia were present 440 Ma ago, and revealing the potential for them to be recognized deeper in the fossil record. [source] Low-Temperature Synthesis of Zinc Oxide NanoparticlesINTERNATIONAL JOURNAL OF APPLIED CERAMIC TECHNOLOGY, Issue 4 2006Po-Yi Wu Crystalline zinc oxide nanoparticles have been prepared by mixing aqueous solutions of zinc nitrate and hexamethylenetetramine (HMT) at 60°C and 80°C. Transmission electron microscopy and X-ray diffraction show that the ZnO nanoparticles of diameters ranging from 15,33 nm and 25,43 nm long are formed. Aspect ratio is observed to range from 1.18 to 1.74 at 60°C and 1.22 to 1.70 at 80°C as the HMT to zinc nitrate concentration ratio increases from 10 to 150. Nanoparticle size decreases as the concentration of HMT increases. Much larger ZnO particles are formed with ammonium hydroxide as a hydrolysis agent without HMT. In summary, HMT is an ammonium-hydroxide source in the reaction, a surfactant for retaining nanosize, and not necessarily a template for ZnO nucleation. [source] Giant Coercive Field of Nanometer- Sized Iron Oxide,ADVANCED MATERIALS, Issue 1 2004J. Jin Nanocrystals of iron oxide in a silica matrix exhibiting a giant Hc value of 2.0,T at room temperature are reported. The nanocomposite was obtained by combining reverse-micelle and sol,gel methods. The nanocrystals of iron oxide are composed of the ,-Fe2O3 phase, with rod-like particles 100,140,nm long and 20,40,nm wide. The Figure shows the hysteresis curve of the nanocrystals. [source] Low-temperature phase transformation and phonon confinement in one-dimensional Ta2O5 nanorodsJOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 3 2010Rupesh S. Devan The thermochromic phase transformations of one-dimensional Ta2O5 nanorods have been analyzed at elevated temperatures ranging from 80 to 300,K. The nanorods, grown in a large-area high-density array, are 14,22,nm wide and approximately 500,nm long. The array contained ,93.5% of the orthorhombic (,) phase and ,6.5% of the tetragonal (,) phase. Low-temperature X-ray diffraction results showed complex and polymorphic thermochromic phase transformations of the ,(001), ,(101) and ,(103) lattice planes of the nanorods, which incorporate (i) ,-to-, (,,,), (ii) ,,,,, and (iii) ,,, phase transitions. In comparison with the Raman scattering of three-dimensional bulk powder and two-dimensional thin films of Ta2O5, there were concurrent Raman blue- and redshifts in the one-dimensional Ta2O5 nanorods, indicating that the molecular vibrations of the nanorods were confined owing to the reduction of size and dimension. [source] Tomato yellow leaf curl virus, the intracellular dynamics of a plant DNA virusMOLECULAR PLANT PATHOLOGY, Issue 1 2003Yedidya Gafni SUMMARY Tomato yellow leaf curl virus is a geminivirus, transmitted by whitefly ( Bemisia tabaci ) and causing the most destructive disease of tomato throughout the Mediterranean region, the Middle East and the tropical regions of Africa and Central America. Affected plants produce either no fruits or a few small fruits. Since it is an ssDNA virus which replicates in the host cell nucleus, the molecular mechanisms involved in the viral nuclear import have been the focus of our studies in recent years and results as well as prospects will be discussed. Taxonomy:Tomato yellow leaf curl virus (TYLCV) is a ssDNA plant virus, a member of the family Geminiviridae , of the genus Begomovirus. Physical properties: ,TYLCV, like all members of Geminiviridae, has geminate (twinned) particles, 18,20 nm in diameter, 30 nm long, apparently consisting of two incomplete T = 1 icosahedra joined together in a structure with 22 pentameric capsomers and 110 identical protein subunits (Fig. 1). Figure 1. Particles of TYLCV. Electron micrograph of purified, negatively stained TYLCV particles. Bar = 100 nm. Disease symptoms: ,Symptoms become visible in tomato in approximately 2,3 weeks after infection (Fig. 2). Leaf symptoms include chlorotic margins, small leaves that are cupped, thick and rubbery. The majority (up to 90%) of flowers abscise after infection, and therefore few fruits are produced. In Israel and elsewhere, weeds bridge the gap as potential perennial host and source of the virus between tomato growing seasons. Figure 2. Tomato yellow leaf curl symptoms on tomato plant. Leaves show yellowing on the edges accompanied by upward curling. Disease control: ,Control of TYLCV is currently based on insecticide treatments and/or physical barriers against the insect vector (Bemisia tabaci), and on tomato breeding programs based on introgression of resistance or tolerance from wild species to cultivated tomato. Useful website: , Breeding Influenza: The Political Virology of Offshore FarmingANTIPODE, Issue 5 2009Robert G. Wallace Abstract:, The geographic extent, xenospecificity, and clinical course of influenza A (H5N1), the bird flu strain, suggest the virus is an excellent candidate for a pandemic infection. Much attention has been paid to the virus's virology, pathogenesis and spread. In contrast, little effort has been aimed at identifying influenza's social origins. In this article, I review H5N1's phylogeographic properties, including mechanisms for its evolving virulence. The novel contribution here is the attempt to integrate these with the political economies of agribusiness and global finance. Particular effort is made to explain why H5N1 emerged in southern China in 1997. It appears the region's reservoir of near-human-specific recombinants was subjected to a phase change in opportunity structure brought about by China's newly liberalized economy. Influenza, 200 nm long, seems able to integrate selection pressures imposed by human production across continental distances, an integration any analysis of the virus should assimilate in turn. [source] | ||||||||||