Acetobacter cellulose pellicle as a temporary skin substitute

Applied Biochemistry and Biotechnology - A bacterial strain with morphological and biochemical properties close toAcetobacter xylinum has been cultured in nonagitated, inverted sucrose- and yeast...     

Thermal analysis of vitamin PP Niacin and niacinamide

Vitamin PP includes two vitamers, niacin and niacinamide which are essential for energy production. Vitamins are sensitive and losses can occur during shelf life and heating processes. Thermal analysis can provide information about thermal behavior of each vitamer relating them with time and/or temperature exposure. The vitamers thermal behavior were studied by TG/DTG and DSC under air and nitrogen atmosphere and the results showed that niacin is more stable than the niacinamide and the decomposition happens by volatilization at 238 °C while niacinamide melts at 129 °C and volatilize at 254 °C when there is the total mass loss in the TG/DTG curves.     

Spheres in Hermitian Symmetric Spaces and Flag Manifolds

This paper contains a proof of the following property of compact irreducible Hermitian symmetric spaces. If H=G/K where G is a compact simply connected simple Lie group, T a maximal torus of G and F(T,H)=|E ₁,...,E _m is the fixed point set of T on H, then for each pair E _i , E _j there is a 2-dimentional sphere N _ij H such that E _i and E _j are antipodal points of N _ij.     

Quantitative Compositional Analyses of Calcareous Rocks for Lime Industry Using LIBS

Here, the potential of laser-induced breakdown spectroscopy (LIBS) in grading calcareous rocks for the lime industry was investigated. In particular, we developed a system equipped with non-intensified detectors operating in scanning mode, defined a suitable data acquisition protocol, and implemented quantitative data processing using both partial least squares regression (PLS-R) and a multilayer perceptron (MLP) neural network. Tests were carried out on 32 samples collected in various limestone quarries, which were preliminarily analyzed using traditional laboratory X-ray fluorescence (XRF); then, they were divided into two groups for calibration and validation. Particular attention was dedicated to the development of LIBS methodology providing a reliable basis for precise material grading. The congruence of the results achieved demonstrates the capability of the present approach to precisely quantify major and minor geochemical components of calcareous rocks, thus disclosing a concrete application perspective within the lime industry production chain.     

Causal Statistical Mechanics Calculation of Initial Cosmic Entropy and Quantum Gravity Prospects

We report on the consequences of applying thecausal laws to the statistical mechanical calculation ofthe initial cosmic entropy. It can be deduced that theentropy density tends to zero as one approaches the initial singularity. This result along withsome quantum gravity considerations lead us to theconclusion that the initial data of the physical fieldsare asymptotically homogeneous in that limit.     

Ultrasound propagation in trabecular bone: A numerical study of the influence of microcracks

The accumulation of microdamage in trabecular bone tissue is suspected of being a predictive indicator of osteoporosis diagnosis. To quantify this microdamage, the Dynamic AcoustoElastic Testing (DAET) method measures the Time Of Flight (TOF) and amplitude variations of transmitted ultrasound (US) pulses, while the bone sample is submitted to a low frequency sinusoidal hydrostatic pressure (opening/closing of microcracks). However, DAET is both sensitive to viscoelastic properties changes and microcracks density. To verify the microcracks density contribution on DAET results, a numerical approach is proposed. Multliple configurations of microdamaged trabecular bone-tissue-like mesh have been simulated. A 2D pseudo-spectral time domain numerical model was then developed to simulate linear wave propagation in heterogeneous solids. The influence of the microcracks number and orientation on the US TOF was particularly investigated. Results are discussed and compared with experimental data obtained from DAET measurements in trabecular bone samples.     

Study of the Robinson-Trautman metrics in the asymptotic future

A systematic study of the Robinson-Trautman metrics in the asymptotic future is presented. As a by-product another technique, that could be used for determining existence of solutions of the Robinson-Trautman equation, is found. All these metrics present an exponential asymptotic limit to the Schwarzschild metric in this regime.     

On the positive energy theorem involving mass and electromagnetic charges

A new theorem relating mass and charges is deduced, which can be applied to more general physical systems than those covered by the theorem of Gibbons and Hull [1].On leave from Instituto de Matématicas Astronomía y Física, Universidad Nacional de Córdoba, (5000) Córdoba, ArgentinaAlfred P. Sloan Fellow; supported in part by a grant from the National Science Foundation