Thermodynamics And Dynamics Of Self Assembled Mesophases Of Multi-Faceted And Multi-Lobed Particles

This work aims at developing a fundamental understanding of how shape of nano/micro-particles affects their thermodynamic phase behavior and dynamic properties. Anisotropic interaction fields encoded in nanoparticles of nonspherical shape can drive their assembly into many complex, ordered or partially ordered structures ("mesophases"). Some of these self-assembled 'phases' are highly desirable for their distinctive electronic, physical and optical properties and are very sensitive to the entropic interactions of their building blocks and other external driving fields. To understand the basic principles controlling formation of these assemblies, we performed systematic simulation studies to explore the effect of 'shape' or excluded volume interactions on the equilibrium mesophase behavior and on selected non-equilibrium mechanical properties of these systems. Monte Carlo simulations performed on a class of spacefilling polyhedral shapes predict formation of various novel liquid-crystalline (LC) and plastic-crystalline phases. By correlating these results with particle anisotropy and rotational symmetry, guidelines for predicting phase behaviour of polyhedral particles are proposed. The effect of quenched size polydispersity on the phase behavior of polyhedral particles is also elucidated by carrying out extensive compression Monte Carlo simulation for polydisperse systems of three distinct shapes. High polydispersities are found to lead to an increased stability of mesophases and the formation of jammed states at high densities. To investigate the effect of anisotropy on dynamics, we performed non-equilibrium molecular dynamics simulations to chart the yielding and shear induced melting behavior of mixed crystalline assemblies of spherical and dimer-shaped particles. Important differences in microstructure, dislocations and stress relaxation behavior emerge with introduction of this shape perturbation (dimer particles), which manifests as non- monotonic yield stress values and a two-stage shear melting behavior. Altogether this work makes some inroads toward a general understanding and taxonomy of the effect of particle shape on the thermophysical properties of colloidal assemblies

Renormalization Group theory outperforms other approaches in statistical comparison between upscaling techniques for porous media

Determining the pressure differential required to achieve a desired flow rate in a porous medium requires solving Darcy's law, a Laplace-like equation, with a spatially varying tensor permeability. In various scenarios, the permeability coefficient is sampled at high spatial resolution, which makes solving Darcy's equation numerically prohibitively expensive. As a consequence, much effort has gone into creating upscaled or low-resolution effective models of the coefficient while ensuring that the estimated flow rate is well reproduced, bringing to fore the classic tradeoff between computational cost and numerical accuracy. Here we perform a statistical study to characterize the relative success of upscaling methods on a large sample of permeability coefficients that are above the percolation threshold. We introduce a new technique based on Mode-Elimination Renormalization-Group theory (MG) to build coarse-scale permeability coefficients. Comparing the results with coefficients upscaled using other methods, we find that MG is consistently more accurate, particularly so due to its ability to address the tensorial nature of the coefficients. MG places a low computational demand, in the manner that we have implemented it, and accurate flow-rate estimates are obtained when using MG-upscaled permeabilities that approach or are beyond the percolation threshold.Comment: 15 pages, 7 figures, Physical Review

WEEE-Cleaners Pvt.Ltd

The business plan presented is based on recycling of electronic waste in India. This work explains the Indian e-waste industry and in details discuses a business plan to set up an e-waste recycling plant in India

WEEE-Cleaners Pvt.Ltd

The business plan presented is based on recycling of electronic waste in India. This work explains the Indian e-waste industry and in details discuses a business plan to set up an e-waste recycling plant in India

Role of volatile fatty acids in nitrogen utilization and urea nitrogen recycling in ruminants

Mechanistic knowledge of urea-N partitioning has the potential to reveal targets that can be manipulated to improve protein efficiency of ruminants, and hence, reduce N excretion to the environment. The objective of this research was to establish the role of rumen volatile fatty acids (VFA), particularly propionate and butyrate, in regulation of N utilization, urea-N recycling and gluconeogenesis in growing lambs. For these studies, sheep were fitted with a rumen cannula and fed a pelleted ration to ≥ 1.5 × maintenance energy intake. Total urine and feces were collected for determination of N balances. In addition, [15N2]urea was infused to determine urea-N kinetics, [13C6]glucose was infused to estimate gluconeogenesis and [ring-D5]phenylalanine was infused to estimate protein fractional synthesis rate (FSR) of rumen tissue. The first study was conducted to evaluate the perturbations in rumen VFA profiles as a result of rumen starch infusion and the association of these perturbations to changes in urea-N kinetics and gluconeogenesis. Sheep (n=4) were infused into the rumen with either water (control) or gelatinized starch (100 g/d) for 9-d periods in a balanced crossover design. The rumen VFA profile was not affected by starch infusion. Fecal N output tended to increase with starch infusion; however, there were no effects on N retention and urinary N excretion. In addition, starch infusion did not alter urea-N entry rate (UER, i.e. synthesis) nor urea-N recycled to the gut (GER); however, starch infusion increased urea-N excreted in feces (UFE). Glucose entry, gluconeogenesis and Cori cycling were increased by starch infusion. The results suggest that under the feeding conditions of this study, starch infusion shifted the elimination of urea-N from urine to feces but this did not lead to an increase in N retention. Two companion studies were conducted to determine the role of rumen butyrate in urea-N recycling and rumen FSR. In Exp 1, sheep (n=4) were given intra-ruminal infusions of either an electrolyte buffer solution (Con-Buf; control) or butyrate dissolved in the buffer solution (But-Buf). In Exp 2, sheep (n=4) were infused into the rumen with iso-energetic (1 MJ/d) solutions of either sodium acetate (Na-Ac; control) or sodium butyrate (Na-But). Butyrate infusion treatments increased the proportion of rumen butyrate whereas acetate infusion increased rumen acetate. No difference in N retention was observed between treatments in either experiment. In Exp 2, UER was reduced by Na-But compared to the Na-Ac control, thus, a higher proportion of urea-N entering the rumen was utilized for microbial protein synthesis. In Exp 1, although But-Buf infusion increased the FSR of rumen papillae, urea kinetics were not altered. This study is the first to directly assess the role of butyrate in urea-N recycling and effects on rumen papillae protein turnover in growing lambs. Under the conditions in the present studies, butyrate did not affect overall N retention in growing sheep; however, butyrate reduced urea synthesis and altered the distribution of urea-N fluxes. Lastly, two companion studies were conducted to determine the role of rumen propionate in urea-N recycling and gluconeogenesis. In Exp 1, sheep (n=6) were continuously infused into the rumen with iso-energetic (1 MJ/d) solutions of either Na-Acetate (control) or Na-Propionate for 9-d periods in a balanced crossover design. In Exp 2, a different group of wether sheep (n=5) were fed on an equivalent protein intake basis either a control or Na-propionate supplemented ration. Propionate treatments increased the proportion of rumen propionate in both experiments. In Exp 1, urea kinetics and N retention were not affected by propionate infusion compared to iso-energetic acetate infusion. However, in Exp 2, the propionate diet increased N retention by ∼50%, which resulted from reductions in UER (−2.1 g urea-N/d) and UUE (−0.8 g urea-N/d). Glucose entry and gluconeogenesis were increased by propionate treatments. Under the conditions of these studies, higher ruminal propionate did not affect urea-N fluxes to the rumen. The results from this research provide an understanding of the role of individual rumen VFA in N retention and urea-N recycling in ruminants

An In Vivo Comparison of Bacterial Colonization with Orthodontic Bracket System

Aim: The objective of this in vivo study was to compare the amount of bacterial colonization associated with metal, self-ligating and ceramic orthodontic brackets . Materials and Method: The study was done on 30 orthodontic patients who were randomly divided in to three groups. Group I bonded with metal brackets wire ligated with steel ligature , Group II bonded with self-ligating brackets and Group III bonded using ceramic brackets wire ligated with elastomeric module. Amount of bacterial colonization was evaluated from right of the maxillary dental arch at day 1 and at day 21, the aerobic and anaerobic bacterial count was then compared. Result: ANOVA test for anaerobic and aerobic log bacterial count showed significant difference between group I, group II and group III observations at 5% level of significance at day 21. Conclusion: The result of this in vivo study concluded that higher bacterial colonization was associated with ceramic brackets ligated with elastomeric modules followed by metal bra ckets ligated with steel ligatures and comparatively less microbial growth was observed in self - ligating brackets