Quantitative determination of the adhesive fracture toughness of CVD diamond to WC-Co cemented carbide

Well-separated diamond particles were nucleated and grown by hot filament chemical vapor deposition (HFCVD) onto WC-Co cemented carbide pretreated by Murakami's reagent and H2O2 + H2SO4 solution. The adhesive strength of diamond particles to WC-Co cemented carbide was quantitatively determined in terms of interface toughness by directly applying an external load to the CVD diamond particles. From the measurement of the maximum load required to scratch off the particles, we determined that the adhesive toughness was 14 J/m(2). This value is more than twice as high as that of CVD diamond on smooth silicon substrate and comparable to the cleavage fracture energy of diamond. The newly developed procedure will allow to check the effectiveness of substrate surface pretreatments for further improving the adhesion level of diamond films on WC-Co. (C) 2000 Elsevier Science S.A. All rights reserved

Radial Spoke Proteins of \u3cem\u3eChlamydomonas\u3c/em\u3e Flagella

The radial spoke is a ubiquitous component of `9+2\u27 cilia and flagella, and plays an essential role in the control of dynein arm activity by relaying signals from the central pair of microtubules to the arms. The Chlamydomonas reinhardtii radial spoke contains at least 23 proteins, only 8 of which have been characterized at the molecular level. Here, we use mass spectrometry to identify 10 additional radial spoke proteins. Many of the newly identified proteins in the spoke stalk are predicted to contain domains associated with signal transduction, including Ca2+-, AKAP- and nucleotide-binding domains. This suggests that the spoke stalk is both a scaffold for signaling molecules and itself a transducer of signals. Moreover, in addition to the recently described HSP40 family member, a second spoke stalk protein is predicted to be a molecular chaperone, implying that there is a sophisticated mechanism for the assembly of this large complex. Among the 18 spoke proteins identified to date, at least 12 have apparent homologs in humans, indicating that the radial spoke has been conserved throughout evolution. The human genes encoding these proteins are candidates for causing primary ciliary dyskinesia, a severe inherited disease involving missing or defective axonemal structures, including the radial spokes

Thin film growth by pulsed laser deposition and properties of 122-type iron-based superconductor AE(Fe1--xCox)2As2 (AE = alkaline earth)

This paper reports comprehensive results on thin-film growth of 122-type iron-pnictide superconductors, AE(Fe1-xCox)2As2 (AE = Ca, Sr, and Ba, AEFe2As2:Co) by a pulsed laser deposition method using a neodymium-doped yttrium aluminum garnet laser as an excitation source. The most critical parameter to produce the SrFe2As2:Co and BaFe2As2:Co phases is the substrate temperature (Ts). It is difficult to produce highly-pure CaFe2As2:Co phase thin film at any Ts. For BaFe2As2:Co epitaxial films, controlling Ts at 800-850 {\deg}C and growth rate to 2.8-3.3 {\AA}/s produced high-quality films with good crystallinity, flat surfaces, and high critical current densities > 1 MA/cm2, which were obtained for film thicknesses from 100 to 500 nm. The doping concentration x was optimized for Ba(Fe1-xCox)2As2 epitaxial films, leading to the highest critical temperature of 25.5 K in the epitaxial films with the nominal x = 0.075.Comment: will be published in the special issue of Superconductor Science and Technology, `Iron12

Observation of the first gravitational microlensing event in a sparse stellar field : the Tago event

We report the observation of the first gravitational microlensing event in a sparse stellar field, involving the brightest (V=11.4 mag) andclosest (~ 1 kpc) source star to date. This event was discovered by an amateurastronomer, A. Tago, on 2006 October 31 as a transient brightening, by ~4.5 mag during a ~15 day period, of a normal A-type star (GSC 3656-1328) in the Cassiopeia constellation. Analysis of both spectroscopic observations and the light curve indicates that this event was caused by gravitational microlensing rather than an intrinsically variable star. Discovery of this single event over a 30 year period is roughly consistent with the expected microlensing rate for the whole sky down to V = 12 mag stars. However, the probability for finding events with such a high magnification (~ 50) is much smaller, by a factor ~1/50, which implies that the true event rate may be higher than expected. This discovery indicates the potential of all sky variability surveys, employing frequent sampling by telescopes with small apertures and wide fields of view, for finding such rare transient events, and using the observations to explore galactic disk structure and search for exo-planets.Comment: 13 pages, 2 tables, 3 figures, accepted by Ap

Further Studies of Bolivian Crocidolite –Part IV: Fibre Width, Fibre Drift and their relation to Mesothelioma Induction: Preliminary Findings

Background The hypothesis that fibre width is a major determinant of mesothelioma induction has been examined by comparative studies of two crocidolites from different sources. Fine fibres fromCapesouthAfricaand the thicker fibre found and used similarly inBolivia.   It is well established that ‘thin’ fibre crocidolite fromCapeSouth Africais extremely mesotheliomagenic. Bolivian crocidolite has a much wider width distribution and relatively little mesothelioma inducing potential.   Methods We analysed the mesothelioma demography inBoliviawhere local crocidolite has been used for decades This was compared with the mesothelioma demography in theItalianCityof Casale Monteferrato whereCapecrocidolite was processed for many decades in the Eternit Asbestos Cement plant producing numerous cases of mesothelioma. We also conducted a limited downwind study from the fiberizing part of the historical operating plant where products containing Bolivian crocidolite were made for sale and use inCochabamba.   Results The demographic study confirmed the absence of a significant mesothelioma excess inBolivia. Despite the extremely high fibre concentrations measured in the plant, no significant fibre levels were detected 100 meters away.   Conclusion These preliminary findings undermine claims such as those made at Casale that crocidolite fibre can drift up to 15 km and remain airborne in quantities sufficient to contribute significantly to mesothelioma induction.   We propose the difference in thickness and the attendant reduction in the percentage ofStantonfibres provides an explanation for the difference in mesothelioma patterns found in each city

Entropy-driven formation of a chiral liquid-crystalline phase of helical filaments

Author Posting. © The Authors, 2006. This article is posted here by permission of American Physical Society for personal use, not for redistribution. The definitive version was published in Physical Review Letters 96 (2006): 018305, doi:10.1103/PhysRevLett.96.018305.We study the liquid-crystalline phase behavior of a concentrated suspension of helical flagella isolated from Salmonella typhimurium. Flagella are prepared with different polymorphic states, some of which have a pronounced helical character while others assume a rodlike shape. We show that the static phase behavior and dynamics of chiral helices are very different when compared to simpler achiral hard rods. With increasing concentration, helical flagella undergo an entropy-driven first order phase transition to a liquid-crystalline state having a novel chiral symmetry.M. S. and R. O. are supported by NIH Grant No. EB002583