Properties of cellulosic fabrics treated by water-repellent emulsions

Water-repellent cotton, jute and linen fabrics have been prepared by treating them with emulsions made of beeswax/stearic acid (BW/SA) mixture. Different BW/SA ratios are tested to find out the best formulation recipe and different additives are incorporated in order to enhance emulsion stability and water repellency rating, such as alkali and metal salts. Triethanolamine (TEA) alkali has been selected for promoting the water repellency results. Cellulosic fabrics are pre-/post-treated with metal salts (aluminium chloride and zirconyl chloride) to enhance their physical attachment to the surfaces. Optimum emulsion ingredients for best results are found to be BW: SA (1:1), in presence of TEA (0.5 mole equivalent of SA) and zirconyl chloride concentration (1 g/L). Treated fabrics have been imparted with a water repellency characteristic, showing a value of 90, 80 and 80 for cotton, linen, and jute fabric respectively. Mechanical properties for treated fabrics are also demonstrated. FTIR spectra of treated fabric show no evidence of any chemical reactions between the substrate and the emulsion. Emulsions show stable rheological behavior upon storing for 3 months

Automated Crack Identification for Cement Paste

The development of an automated procedure for the identification of microcracks in cementitious materials is described. The degree and nature of microcracking is measured using backscattered electron images obtained with an integrated scanning electron microscope/image analysis system. Multiple images for specimens are analyzed using a computer program developed to identify and measure microcracks within the individual phases of cement paste. The procedure is developed to assist in the determination of the roles played by individual phases in cement paste in the formation and propagation of microcracks. Procedures for specimen testing, preparation, imaging, and crack analysis are described, along with a description of the development of the analysis program. The analysis capabilities of the program are demonstrated. The gray level of epoxy-filled cracks in polished cement paste specimens is affected by the atomic number density of underlying and adjacent phases. As a result, cracks cannot be identified based on gray level alone.Epoxy-filled cracks in polished cement paste specimens can be identified based on local changes in gray level and the application of geometric requirements; and combined procedures that establish the floor of a crack, minimum gradient and gray level adjacent to cracks, and minimum differences in gray level between the floor of a crack and adjacent solid phases provide a reproducible and consistent technique for crack identification in cement paste

HIRA directly targets the enhancers of selected cardiac transcription factors during in vitro differentiation of mouse embryonic stem cells

HIRA is a histone chaperone known to modulate gene expression through the deposition of H3.3. Conditional knockout of Hira in embryonic mouse hearts leads to cardiac septal defects. Loss of function mutation in HIRA, together with other chromatin modifiers, was found in patients with congenital heart diseases. However, the effects of HIRA on gene expression at earlier stages of cardiogenic mesoderm differentiation have not yet been studied. Differentiation of mouse embryonic stem cells (mESCs) towards cardiomyocytes mimics some of these early events and is an accepted model of these early stages. We performed RNA-Seq and H3.3-HA ChIP-seq on both WT and Hira-null mESCs and early cardiomyocyte progenitors of both genotypes. Analysis of RNA-seq data showed differential down regulation of cardiovascular development-related genes in Hira-null cardiomyocytes compared to WT cardiomyocytes. We found HIRA-dependent H3.3 deposition at these genes. In particular, we observed that HIRA influenced directly the expression of the transcription factors Gata6, Meis1 and Tbx2, essential for cardiac septation, through H3.3 deposition. We therefore identified new direct targets of HIRA during cardiac differentiation

The Energy-Momentum Tensor in Noncommutative Gauge Field Models

We discuss the different possibilities of constructing the various energy-momentum tensors for noncommutative gauge field models. We use Jackiw's method in order to get symmetric and gauge invariant stress tensors--at least for commutative gauge field theories. The noncommutative counterparts are analyzed with the same methods. The issues for the noncommutative cases are worked out.Comment: 11 pages, completed reference

D-brane orbiting NS5-branes

We study real time dynamics of a Dp-brane orbiting a stack of NS5-branes. It is generally known that a BPS D-brane moving in the vicinity of NS5-branes becomes unstable due to the presence of tachyonic degree of freedom induced on the D-brane. Indeed, the D-brane necessarily falls into the fivebranes due to gravitational attraction and eventually collapses into a pressureless fluid. Such a decay of the D-brane is known to be closely related to the rolling tachyon problem. In this paper we show that in special cases the decay of D-brane caused by gravitational attraction can be avoided. Namely for certain values of energy and angular momentum the D-brane orbits around the fivebranes, maintaining certain distance from the fivebranes all the time, and the process of tachyon condensation is suppressed. We show that the tachyonic degree of freedom induced on such a D-brane really disappears and the brane returns to a stable D-brane.Comment: 12 pages, latex, added referenc

Relativistic D-brane Scattering is Extremely Inelastic

We study the effects of quantum production of open strings on the relativistic scattering of D-branes. We find strong corrections to the brane trajectory from copious production of highly-excited open strings, whose typical oscillator level is proportional to the square of the rapidity. In the corrected trajectory, the branes rapidly coincide and remain trapped in a configuration with enhanced symmetry. This is a purely stringy effect which makes relativistic brane collisions exceptionally inelastic. We trace this effect to velocity-dependent corrections to the open-string mass, which render open strings between relativistic D-branes surprisingly light. We observe that pair-creation of open strings could play an important role in cosmological scenarios in which branes approach each other at very high speeds.Comment: 30 pages; added references and a comment about velocity-dependent masse

Making the hyper--K\"ahler structure of N=2 quantum string manifest

We show that the Lorentz covariant formulation of N=2 string in a curved space reveals an explicit hyper--K\"ahler structure. Apart from the metric, the superconformal currents couple to a background two--form. By superconformal symmetry the latter is constrained to be holomorphic and covariantly constant and allows one to construct three complex structures obeying a (pseudo)quaternion algebra.Comment: 8 pages, no figures, PACS: 04.60.Ds; 11.30.Pb, Keywords: N=2 string, hyper-K\"ahler geometry. Presentation improved, references added. The version to appear in PR

Dynamical noncommutativity and Noether theorem in twisted phi^*4 theory

A \star-product is defined via a set of commuting vector fields X_a = e_a^\mu (x) \partial_\mu, and used in a phi^*4 theory coupled to the e_a^\mu (x) fields. The \star-product is dynamical, and the vacuum solution phi =0, e_a^\mu (x)=delta_a^\mu reproduces the usual Moyal product. The action is invariant under rigid translations and Lorentz rotations, and the conserved energy-momentum and angular momentum tensors are explicitly derived.Comment: 15 pages LaTeX, minor typos, added reference