Ultrasonic Machining as an Aid to Ceramic Etching

Ceramics are difficult to etch. Their chemical inertness makes them very stable and often hot etching techniques are required to obtain their microstructures. This communication reports a technique developed to ease the process of ceramic etching

2-Meth­oxy-3,4-diphenyl­phenol

The title compound, C19H16O2, was isolated as the major product after the solid-state photochemical reaction of 2-meth­oxy-4,4-diphenyl­cyclo­hexa-2,5-dienone. The dihedral angles between the central ring and pendant benzene rings are 60.76 (6) and 51.64 (6)°. The O—C vector of the meth­oxy group is almost perpendicular to the plane of the central ring as indicated by the C—C—O—C torsion angle of 94.89 (18)°. Hydrogen-bonded dimers are formed in the crystal structure via O—H⋯O inter­actions. The data were collected at room temperature on a Bruker SMART X2S diffractometer in the automated mode and processed manually thereafter

Solving the initial conditions problem for modified gravity theories

Modified gravity theories such as Einstein scalar Gauss Bonnet (EsGB) contain higher derivative terms in the spacetime curvature in their action, which results in modifications to the Hamiltonian and momentum constraints of the theory. In principle, such modifications may affect the principal part of the operator in the resulting elliptic equations, and so further complicate the already highly non-linear, coupled constraints that apply to the initial data in numerical relativity simulations of curved spacetimes. However, since these are effective field theories, we expect the additional curvature terms to be small, which motivates treating them simply as an additional source in the constraints, and iterating to find a solution to the full problem. In this work we implement and test a modification to the CTT/CTTK methods of solving the constraints for the case of the most general four derivative, parity invariant scalar-tensor theory, and show that solutions can be found in both asymptotically flat/black hole and periodic/cosmological spacetimes, even up to couplings of order unity in the theory. Such methods will allow for numerical investigations of a much broader class of initial data than has previously been possible in these theories, and should be straightforward to extend to similar models in the Horndeski class.Comment: 9 pages, 4 figures, comments welcome

Digital image processing applications in the ignition and combustion of char/coal particles

Digital image processing, is employed in this remarch study in order to visually investigate the ignition and combustion characteristics of isolated char/coal particles as well as the effect of interactivecombustion in two-particle char/coal arrays. Preliminary experiments are conducted on miniature isolated candles as well as two-candle arrays

Nonlinear Modes of Liquid Drops as Solitary Waves

The nolinear hydrodynamic equations of the surface of a liquid drop are shown to be directly connected to Korteweg de Vries (KdV, MKdV) systems, giving traveling solutions that are cnoidal waves. They generate multiscale patterns ranging from small harmonic oscillations (linearized model), to nonlinear oscillations, up through solitary waves. These non-axis-symmetric localized shapes are also described by a KdV Hamiltonian system. Recently such ``rotons'' were observed experimentally when the shape oscillations of a droplet became nonlinear. The results apply to drop-like systems from cluster formation to stellar models, including hyperdeformed nuclei and fission.Comment: 11 pages RevTex, 1 figure p

The clustering instability of inertial particles spatial distribution in turbulent flows

A theory of clustering of inertial particles advected by a turbulent velocity field caused by an instability of their spatial distribution is suggested. The reason for the clustering instability is a combined effect of the particles inertia and a finite correlation time of the velocity field. The crucial parameter for the clustering instability is a size of the particles. The critical size is estimated for a strong clustering (with a finite fraction of particles in clusters) associated with the growth of the mean absolute value of the particles number density and for a weak clustering associated with the growth of the second and higher moments. A new concept of compressibility of the turbulent diffusion tensor caused by a finite correlation time of an incompressible velocity field is introduced. In this model of the velocity field, the field of Lagrangian trajectories is not divergence-free. A mechanism of saturation of the clustering instability associated with the particles collisions in the clusters is suggested. Applications of the analyzed effects to the dynamics of droplets in the turbulent atmosphere are discussed. An estimated nonlinear level of the saturation of the droplets number density in clouds exceeds by the orders of magnitude their mean number density. The critical size of cloud droplets required for clusters formation is more than $20 \mu$m.Comment: REVTeX 4, 15 pages, 2 figures(included), PRE submitte

Design and development of power-operated continuous-run potting machine for seedling-nursery

Potting is still a manual operation in plantation, forestry, and 11 other horticultural nurseries in India and the preparation of pot-mixture and filling in polybags are crucial tasks and are time consuming. Therefore, a poweroperated continuous-run machine was specially designed, fabricated, and tested to master seedling-nursery management capable of mixing, pulverizing, sieving, and filling of pot ingredients in polybags. The machine is a vertical freestanding unit mounted on four legs and consists of 3-hp motor, feed-hopper, pulverizing chamber with 8-numbers of paddles, sieving compartment operated by a slider-crank mechanism, vending instrumentation, and outlet. Ingredients like soil, sand, granite power, farmyard manure, and compost are fed from the top and the pot-mixture is collected at the bottom. Electronic vending is the novelty of the machine, which permits filling pot-mixture at set quantity at set time-gap. Aggregate analysis, degree of pulverization, and other physical parameters of machine-made mixture are at recommended level as well as on par with manually-made pot-mixture. More proportion (81.8%) of desirable level of aggregate was achieved with machine compared in manual method (79.5%) resulted in improved quality of the mixture for seedling establishment. Bagging through machine worked out 71.4% cost-saving and 80.2% time-saving. The machine is recommended for nursery-holders around the nation since the machine can provide pot-mixture for development of saplings of 30 000 numbers per month in a commercial nursery

Physicochemical analysis of rotavirus segment 11 supports a 'modified panhandle' structure and not the predicted alternative tRNA-like structure (TRLS)

.Rotaviruses are a major cause of acute gastroenteritis, which is often fatal in infants. The viral genome consists of 11 double-stranded RNA segments, but little is known about their cis-acting sequences and structural elements. Covariation studies and phylogenetic analysis exploring the potential structure of RNA11 of rotaviruses suggested that, besides the previously predicted "modified panhandle" structure, the 5' and 3' termini of one of the isoforms of the bovine rotavirus UKtc strain may interact to form a tRNA-like structure (TRLS). Such TRLSs have been identified in RNAs of plant viruses, where they are important for enhancing replication and packaging. However, using tRNA mimicry assays (in vitro aminoacylation and 3'- adenylation), we found no biochemical evidence for tRNA-like functions of RNA11. Capping, synthetic 3' adenylation and manipulation of divalent cation concentrations did not change this finding. NMR studies on a 5'- and 3'-deletion construct of RNA11 containing the putative intra-strand complementary sequences supported a predominant panhandle structure and did not conform to a cloverleaf fold despite the strong evidence for a predicted structure in this conserved region of the viral RNA. Additional viral or cellular factors may be needed to stabilise it into a form with tRNA-like properties