The influence of wind-induced compression failures on the mechanical properties of spruce structural timber

Compression failures (CF) are defects in the wood structure in the form of buckled fibres. They are a well-known 'natural' phenomenon in softwood trees exposed to frequent or strong winds, but their influence on the utilisation of timber is still debated. While a reduction of the mechanical properties in bending and tension at the fibre level and in small clear specimens is generally acknowledged, the effect is less obvious with structural timber in the presence of other defects such as knots or grain deviations. In the presented case study a statistically significant reduction of the moduli of rupture and elasticity in bending is observed in a sample of 563 squared timber beams, but the characteristic values of the mechanical properties still exceed the limits for the strength classes of visually graded structural timber (according to the Swiss standard SIA 265). Nevertheless, because of the potential safety risk by the more brittle fracture behaviour, it is recommended to exclude timber with detected CF from use in load bearing structures stressed in tension or bendin

One dimensional chain of quantum molecule motors as a mathematical physics model for muscle fibre

A quantum chain model of many molecule motors is proposed as a mathematical physics theory on the microscopic modeling of classical force-velocity relation and tension transients of muscle fibre. We proposed quantum many-particle Hamiltonian to predict the force-velocity relation for the slow release of muscle fibre which has no empirical relation yet, it is much more complicate than hyperbolic relation. Using the same Hamiltonian, we predicted the mathematical force-velocity relation when the muscle is stimulated by alternative electric current. The discrepancy between input electric frequency and the muscle oscillation frequency has a physical understanding by Doppler effect in this quantum chain model. Further more, we apply quantum physics phenomena to explore the tension time course of cardiac muscle and insect flight muscle. Most of the experimental tension transients curves found their correspondence in the theoretical output of quantum two-level and three-level model. Mathematically modeling electric stimulus as photons exciting a quantum three-level particle reproduced most tension transient curves of water bug Lethocerus Maximus.Comment: 16 pages, 12 figures, Arguments are adde

Coronal Emission Measures and Abundances for Moderately Active K Dwarfs Observed by Chandra

We have used Chandra to resolve the nearby 70 Oph (K0 V+K5 V) and 36 Oph (K1 V+K1 V) binary systems for the first time in X-rays. The LETG/HRC-S spectra of all four of these stars are presented and compared with an archival LETG spectrum of another moderately active K dwarf, Epsilon Eri. Coronal densities are estimated from O VII line ratios and emission measure distributions are computed for all five of these stars. We see no substantial differences in coronal density or temperature among these stars, which is not surprising considering that they are all early K dwarfs with similar activity levels. However, we do see significant differences in coronal abundance patterns. Coronal abundance anomalies are generally associated with the first ionization potential (FIP) of the elements. On the Sun, low-FIP elements are enhanced in the corona relative to high-FIP elements, the so-called "FIP effect." Different levels of FIP effect are seen for our stellar sample, ranging from 70 Oph A, which shows a prominent solar-like FIP effect, to 70 Oph B, which has no FIP bias at all or possibly even a weak inverse FIP effect. The strong abundance difference exhibited by the two 70 Oph stars is unexpected considering how similar these stars are in all other respects (spectral type, age, rotation period, X-ray flux). It will be difficult for any theoretical explanation for the FIP effect to explain how two stars so similar in all other respects can have coronae with different degrees of FIP bias. Finally, for the stars in our sample exhibiting a FIP effect, a curious difference from the solar version of the phenomenon is that the data seem to be more consistent with the high-FIP elements being depleted in the corona rather than a with a low-FIP enhancementComment: 35 pages, 8 figures, AASTEX v5.0 plus EPSF extensions in mkfig.sty; accepted by Ap

Quality control and improvement of structural timber

Abstract Modern applications of structural timber like e.g. in the field of multi-storey domiciles or large span structures require graded timber products with sufficient and in many cases high performing mechanical properties. This can only be reached by means of advanced methods for quality control within the production process of structural timber. In this paper, quality control and improvement of structural timber is subdivided into three constitutive sub-items: 1) process monitoring, 2) process calibration and 3) process optimization. The paper at hand can be considered as a summary of the authors' investigations and contributions within COST action E53. Different approaches for quality control and improvement of structural timber by means of machine grading are described. An optimized combination of the three sub-items of process control may lead to an enhanced recovery of the timber material quality and to an improved benefit and reliability in the graded timber material

Semiempirical Quantum-Chemical Orthogonalization-Corrected Methods: Theory, Implementation, and Parameters

Semiempirical orthogonalization-corrected methods (OM1, OM2, and OM3) go beyond the standard MNDO model by explicitly including additional interactions into the Fock matrix in an approximate manner (Pauli repulsion, penetration effects, and core–valence interactions), which yields systematic improvements both for ground-state and excited-state properties. In this Article, we describe the underlying theoretical formalism of the OMx methods and their implementation in full detail, and we report all relevant OMx parameters for hydrogen, carbon, nitrogen, oxygen, and fluorine. For a standard set of mostly organic molecules commonly used in semiempirical method development, the OMx results are found to be superior to those from standard MNDO-type methods. Parametrized Grimme-type dispersion corrections can be added to OM2 and OM3 energies to provide a realistic treatment of noncovalent interaction energies, as demonstrated for the complexes in the S22 and S66×8 test sets

Understanding the hydration process of salts:the impact of a nucleation barrier

The solid-state hydration of salts has gained particular interest within the frame of thermochemical energy storage. In this work, the water vapor pressure–temperature (p–T) phase diagram of the following thermochemical salts was constructed by combining equilibrium and nonequilibrium hydration experiments: CuCl2, K2CO3, MgCl2·4H2O, and LiCl. The hydration of CuCl2 and K2CO3 involves a metastable zone of ca. 10 K, and the induction times preceding hydration are well-described by classical homogeneous nucleation theory. It is further shown for K2CO3 (metastable) and MgCl2·4H2O (not metastable) through solubility calculations that the phase transition is not mediated by bulk dissolution. We conclude that the hydration proceeds as a solid–solid phase transition, mobilized by a wetting layer, where the mobility of the wetting layer increases with increasing vapor pressure. In view of heat storage application, the finding of metastability in thermochemical salts reveals the impact of nucleation and growth processes on the thermochemical performance and demonstrates that practical aspects like the output temperature of a thermochemical salt are defined by its metastable zone width (MZW) rather than its equilibrium phase diagram. Manipulation of the MZW by e.g. prenucleation or heterogeneous nucleation is a potential way to raise the output temperature and power on material level in thermochemical applications

An investigation into the effects of solvent content on the image quality and stability of ink jet digital prints under varied storage conditions

Increasing numbers of galleries, museums and archives are including ink jet printed materials into their collections, and therefore displays. There is evidence that the instability of these prints is such that images can suffer deterioration in print quality or in extreme cases, a loss of information over an extended period of time. This is shorter than the period typically required for perceptible deterioration to occur in many other paper-based artworks. The image stability of prints is affected by a number of factors some of which have already been studied. However the role played by the ink solvent in the loss of image quality has yet to be explored. This paper will outline research being undertaken to investigate the effects of solvent content which may increase/promote the loss in image quality of the hard copy prints when stored or displayed under a range of temperature and humidity conditions

Suitability of Small and Large Size Dairy Cows in a Pasture-Based Production System

Pasture-based dairy production with greatly reduced supplemental feeding and block-calving in spring is increasingly applied in Switzerland. The prevalent cow type has been selected mainly for high individual production in a barn feeding system with balanced diet. This cow type has continuously increased in size over the last 30 years. The question arises whether this type is suitable for the new system, and particularly if cow size is a critical factor. Theoretically a large, heavy type of cow has a higher intake capacity, while the nutrient requirements for a small, light type are easier to satisfy

Cytochrome c Reduction by H2S Potentiates Sulfide Signaling.

This is the author accepted manuscript. The final version is available from American Chemical Society via the DOI in this record.Hydrogen sulfide (H2S) is an endogenously produced gas that is toxic at high concentrations. It is eliminated by a dedicated mitochondrial sulfide oxidation pathway, which connects to the electron transfer chain at the level of complex III. Direct reduction of cytochrome c (Cyt C) by H2S has been reported previously but not characterized. In this study, we demonstrate that reduction of ferric Cyt C by H2S exhibits hysteretic behavior, which suggests the involvement of reactive sulfur species in the reduction process and is consistent with a reaction stoichiometry of 1.5 mol of Cyt C reduced/mol of H2S oxidized. H2S increases O2 consumption by human cells (HT29 and HepG2) treated with the complex III inhibitor antimycin A, which is consistent with the entry of sulfide-derived electrons at the level of complex IV. Cyt C-dependent H2S oxidation stimulated protein persulfidation in vitro, while silencing of Cyt C expression decreased mitochondrial protein persulfidation in a cell culture. Cyt C released during apoptosis was correlated with persulfidation of procaspase 9 and with loss of its activity. These results reveal a potential role for the electron transfer chain in general, and Cyt C in particular, for potentiating sulfide-based signaling.This work was supported by the French State in the frame of the “Investments for the future” Programme IdEx Bordeaux, reference ANR-10-IDEX-03-02, and by an ATIP-AVENIR grant (to M.R.F.), the National Institutes of Health (GM112455 to R.B. and R01GM113030 to M.D.P.), the Medical Research Council, UK (MR/M022706/1 to M.W.), the National Science Foundation (DGE-1309047 to A.K.S.), and the Brian Ridge Scholarship (R.T.). The authors are grateful to M.-F. Giraud for the help with purification of mitochondria