A Robust Solution Procedure for Hyperelastic Solids with Large Boundary Deformation

Compressible Mooney-Rivlin theory has been used to model hyperelastic solids, such as rubber and porous polymers, and more recently for the modeling of soft tissues for biomedical tissues, undergoing large elastic deformations. We propose a solution procedure for Lagrangian finite element discretization of a static nonlinear compressible Mooney-Rivlin hyperelastic solid. We consider the case in which the boundary condition is a large prescribed deformation, so that mesh tangling becomes an obstacle for straightforward algorithms. Our solution procedure involves a largely geometric procedure to untangle the mesh: solution of a sequence of linear systems to obtain initial guesses for interior nodal positions for which no element is inverted. After the mesh is untangled, we take Newton iterations to converge to a mechanical equilibrium. The Newton iterations are safeguarded by a line search similar to one used in optimization. Our computational results indicate that the algorithm is up to 70 times faster than a straightforward Newton continuation procedure and is also more robust (i.e., able to tolerate much larger deformations). For a few extremely large deformations, the deformed mesh could only be computed through the use of an expensive Newton continuation method while using a tight convergence tolerance and taking very small steps.Comment: Revision of earlier version of paper. Submitted for publication in Engineering with Computers on 9 September 2010. Accepted for publication on 20 May 2011. Published online 11 June 2011. The final publication is available at http://www.springerlink.co

Spectral studies of some hydroxy-derivatives of anthraquinones

The u.v., visible, and i.r. spectra of several hydroxy-anthraquinones are discussed and the bands are assigned. These bands are compared with those of anthracene and anthraquinone. The band at 207 nm. is assigned to a n-sigma* transition; the bands at 252, 272, and 326 nm. are assigned by measuring spectra in solvents of various polarities. The stability constant for the 12-dihydroxyanthraquinone-ethanol complex is obtained

Array comparative genomic hybridization screening in IVF significantly reduces number of embryos available for cryopreservation

Objective During IVF, non-transferred embryos are usually selected for cryopreservation on the basis of morphological criteria. This investigation evaluated an application for array comparative genomic hybridization (aCGH) in assessment of surplus embryos prior to cryopreservation. Methods First-time IVF patients undergoing elective single embryo transfer and having at least one extra non-transferred embryo suitable for cryopreservation were offered enrollment in the study. Patients were randomized into two groups: Patients in group A (n=55) had embryos assessed first by morphology and then by aCGH, performed on cells obtained from trophectoderm biopsy on post-fertilization day 5. Only euploid embryos were designated for cryopreservation. Patients in group B (n=48) had embryos assessed by morphology alone, with only good morphology embryos considered suitable for cryopreservation. Results Among biopsied embryos in group A (n=425), euploidy was confirmed in 226 (53.1%). After fresh single embryo transfer, 64 (28.3%) surplus euploid embryos were cryopreserved for 51 patients (92.7%). In group B, 389 good morphology blastocysts were identified and a single top quality blastocyst was selected for fresh transfer. All group B patients (48/48) had at least one blastocyst remaining for cryopreservation. A total of 157 (40.4%) blastocysts were frozen in this group, a significantly larger proportion than was cryopreserved in group A (p=0.017, by chi-squared analysis). Conclusion While aCGH and subsequent frozen embryo transfer are currently used to screen embryos, this is the first investigation to quantify the impact of aCGH specifically on embryo cryopreservation. Incorporation of aCGH screening significantly reduced the total number of cryopreserved blastocysts compared to when suitability for freezing was determined by morphology only. IVF patients should be counseled that the benefits of aCGH screening will likely come at the cost of sharply limiting the number of surplus embryos available for cryopreservation

Band structure in classical field theory

Stability and instability bands in classical mechanics are well-studied in connection with systems such as described by the Mathieu equation. We examine whether such band structure can arise in classical field theory in the context of an embedded kink in 1+1 dimensions. The static embedded kink is unstable to perturbations but we show that if the kink is dynamic it can exhibit stability in certain parameter bands. Our results are relevant for estimating the lifetimes of various embedded defects and, in particular, loops of electroweak Z-string.Comment: 6 pages, 4 fig. Reference added, Fig. 3 updated with improved numerical code, minor comments added. Version to be published in Phys. Rev.

Effectiveness and Mechanisms of Action of Whitening Dentifrices on Enamel Extrinsic Stains

poster abstractWhitening dentifrices utilize different approaches for stain removal and/or prevention, including the use of abrasive, oxidizing and chemical cleaning agents. The objectives of this in vitro study were: 1. to compare the whitening effect of commercial whitening and non-whitening dentifrices; 2. to verify the mechanism of action of whitening dentifrices by contrasting two experimental models: chemical (toothpaste exposure only) and chemo-mechanical (toothpaste exposure with tooth brushing abrasion). Two hundred fifty six bovine enamel specimens (10x10mm) were prepared and partially stained. They were assigned to 8 groups: 6 whitening dentifrices, 1 non-whitening reference dentifrice and deionized water (control); and further divided in 2 subgroups (n=16) according to the experimental models: chemical or chemo-mechanical. Specimens were daily exposed to dentifrice slurries 2x/day for 1min and brushed or not, according to each model. In between dentifrice treatments, specimens were exposed to the staining solution for 5h. This protocol was repeated for 5 consecutive days and enamel color changes (Delta E) were measured by spectrophotometry, after each day. The abrasivity of the toothpastes was determined using standard test (ISO 11609). Significantly higher Delta E values (whitening effect) were observed for all groups (p0.05). Whitening dentifrices can be effective preventing/removing enamel surface staining, when associated to tooth brushing abrasion. This seemed to be modulated mainly by the abrasive level of the tested toothpastes, with no action attributed to the chemical agents

Solitary wave dynamics in time-dependent potentials

We rigorously study the long time dynamics of solitary wave solutions of the nonlinear Schr\"odinger equation in {\it time-dependent} external potentials. To set the stage, we first establish the well-posedness of the Cauchy problem for a generalized nonautonomous nonlinear Schr\"odinger equation. We then show that in the {\it space-adiabatic} regime where the external potential varies slowly in space compared to the size of the soliton, the dynamics of the center of the soliton is described by Hamilton's equations, plus terms due to radiation damping. We finally remark on two physical applications of our analysis. The first is adiabatic transportation of solitons, and the second is Mathieu instability of trapped solitons due to time-periodic perturbations.Comment: 38 pages, some typos corrected, one reference added, one remark adde

Checklist of Free-living Protozoa from Fresh water bodies of Pravara River at Ahmednagar Regions

The current research work covers the checklist of free-living ciliated protozoa from freshwater bodies of Pravara River of Ahmednagar regions, Maharashtra (India). 54 samples were collected during one year from January to December 2021.A total of 14 species of ciliates were recorded. The identification has been made mainly on the basis of body shape, size, arrangements of cilia, and the structure of macro- and micronucleus. In this year, the maximum prevalence of ciliates was observed in class Oligohymenophorea, which constituted (75.92%) and class Heterotrichea, accounted for (48.14%) respectively of the total rate of the samples. Moreover, the minimum prevalence of ciliates was observed in class Spirotichea, which constituted (22.22%), and the least percentage in class Prostomatea (i.e. 5.55%).&nbsp

Turmeric dyeing and chitosan/titanium dioxide nanoparticle colloid finishing of cotton fabric

The possibility of combining the finishing and natural dyeing of cotton fabric has been studied using a single-stage, paddry-cure technique, by treating it with chitosan/titanium dioxide nanoparticle colloids and turmeric dye. Differentparameters have been studied to optimise the process, such as the chitosan/TiO2 nanoparticle colloid concentration, citricacid crosslinker concentration, sodium pyrophosphate catalyst concentration, dye concentration, pH, curing time, andtemperature. To investigate the effects of combined treatment on the dyeing and functional properties of the treated cottonfabric, its ultraviolet protection factor, antibacterial activity, self-cleaning properties, rigidity, colour strength (K/S), fastnessbehaviour, nitrogen content, and wettability are determined. In addition, the cotton fabric surface is characterised usingscanning electron microscopy. The samples treated with chitosan/TiO2 in the presence of citric acid exhibit excellentprotection against ultraviolet radiation as well as antibacterial activity. The optimum conditions are 0.75% TiO2 (w/v), 10% dye (w/v), 2.5% chitosan (w/v), 30 g/L citric acid, 4 g/L sodium pyrophosphate, 70°C drying temp. and 5 min drying time,180°C curing temp. and 2 min curing time. The results also indicate the efficiency of the treatment in improving the selfcleaningproperties of the fabric. A significant improvement in the colour fastness is observed for the treated fabrics