Peeling from a patterned thin elastic film

Inspired by the observation that many naturally occurring adhesives arise as textured thin films, we consider the displacement controlled peeling of a flexible plate from an incision-patterned thin adhesive elastic layer. We find that crack initiation from an incision on the film occurs at a load much higher than that required to propagate it on a smooth adhesive surface; multiple incisions thus cause the crack to propagate intermittently. Microscopically, this mode of crack initiation and propagation in geometrically confined thin adhesive films is related to the nucleation of cavitation bubbles behind the incision which must grow and coalesce before a viable crack propagates. Our theoretical analysis allows us to rationalize these experimental observations qualitatively and quantitatively and suggests a simple design criterion for increasing the interfacial fracture toughness of adhesive films.Comment: 8 pages, To appear in Proceedings of Royal Society London, Ser.

In silico characterization of microbial electrosynthesis for metabolic engineering of biochemicals

<p>Abstract</p> <p>Background</p> <p>A critical concern in metabolic engineering is the need to balance the demand and supply of redox intermediates such as NADH. Bioelectrochemical techniques offer a novel and promising method to alleviate redox imbalances during the synthesis of biochemicals and biofuels. Broadly, these techniques reduce intracellular NAD⁺to NADH and therefore manipulate the cell's redox balance. The cellular response to such redox changes and the additional reducing power available to the cell can be harnessed to produce desired metabolites. In the context of microbial fermentation, these bioelectrochemical techniques can be used to improve product yields and/or productivity.</p> <p>Results</p> <p>We have developed a method to characterize the role of bioelectrosynthesis in chemical production using the genome-scale metabolic model of <it>E. coli</it>. The results in this paper elucidate the role of bioelectrosynthesis and its impact on biomass growth, cellular ATP yields and biochemical production. The results also suggest that strain design strategies can change for fermentation processes that employ microbial electrosynthesis and suggest that dynamic operating strategies lead to maximizing productivity.</p> <p>Conclusions</p> <p>The results in this paper provide a systematic understanding of the benefits and limitations of bioelectrochemical techniques for biochemical production and highlight how electrical enhancement can impact cellular metabolism and biochemical production.</p

Electronic Structure of Sr_2FeMoO_6

We have analysed the unusual electronic structure of Sr_2FeMoO_6 combining ab-initio and model Hamiltonian approaches. Our results indicate that there are strong enhancements of the intraatomic exchange strength at the Mo site as well as the antiferromagnetic coupling strength between Fe and Mo sites. We discuss the possibility of a negative effective Coulomb correlation strength (U_{eff}) at the Mo site due to these renormalised interaction strengths.Comment: To appear in Phys. Rev. Let

Low-Temperature Spin Dynamics of Doped Manganites: roles of Mn-t2g and eg and O-2p states

The low-temperature spin dynamics of doped manganites have been analyzed within a tight-binding model, the parameters of which are estimated by mapping the results of ab initio density functional calculations onto the model. This approach is found to provide a good description of the spin dynamics of the doped manganites, observed earlier within the ab initio calculations. Our analysis not only provides some insight into the roles of the eg and the t2g states but also indicates that the oxygen p states play an important role in the spin dynamics. This may cast doubt on the adaptability of the conventional model Hamiltonian approaches to the analysis of spin dynamics of doped manganites.Comment: 12 pages; Includes 5 figure

DOCKING STUDIES ON ANTIDIABETIC MOLECULAR TARGETS OF PHYTOCHEMICAL COMPOUNDS OF SYZYGIUM CUMINI (L.) SKEELS

ABSTRACTObjectives: Different parts of jamun tree (Syzygium cumini L. skeels) which belongs to the family - Myrtaceae are well-known for their antidiabeticactivity. Traditional practitioners in India are using the leaf, bark, and fruits of this medicinal plant over many centuries to manage the diabeticpatients. Although several research works have been conducted to prove the efficacy of this plant extracts and also to explore the active principles ofthis plant drug, there is no information regarding the interaction of phytoconstituents of jamun tree with diabetic targets at the molecular level. Hence,this study focused to apply a computational approach to reveal the interaction of molecules of jamun tree with antidiabetic targets.Methods: Lamarckian genetic algorithm methodology was used for docking of 22 phytoconstituents with α-amylase, a key enzyme that involved incarbohydrate metabolism using Autodock software.Results: Analysis of binding energy of ligands with target receptors was remarkably lower especially for friedelin (−9.54 kcal/mol), epifriedelanol(−8.98 kcal/mol), betulinic acid (−8.60 kcal/mol), beta-sitosterol (−8.56 kcal/mol), petunidin-3-gentiobioside (−7.52 kcal/mol), kaempferol (−7.08kcal/mol), petunidin (−6.21 kcal/mol), quercetin (−6.03 kcal/mol), myricetin (−5.80 kcal/mol), and bergenin (−5.27 kcal/mol) when compared tothe synthetic drug acarbose (−2.43 kcal/mol).Conclusion: Potential molecules identified from this study could be considered as a lead to design/synthesize anti-diabetic drug molecules inpharmaceutical industry.Keywords: Jamun tree, Syzygium cumini, Phytochemicals, Diabetes, α-amylase, Molecular docking

A nucleosome-free dG-dC-rich sequence element promotes constitutive transcription of the essential yeast RIO1 gene

RIO1 is an essential gene that encodes a protein serine kinase and is transcribed constitutively at a very low level. Transcriptional activation of RIO1 dispenses with a canonical TATA box as well as with classical transactivators or specific DNAbinding factors. Instead, a dGdCrich sequence element, that is located 40 to 48 bp upstream the single site of mRNA initiation, is essential and presumably constitutes the basal promoter. In addition, we demonstrate here that this promoter element comprises a nucleosomefree gap which is centered at the dGdC tract and flanked by two positioned nucleosomes. This element is both, necessary and sufficient, for basal transcription initiation at the RIO1 promoter and, thus, constitutes a novel type of core promoter element

Environmental Issues to be Addressed in Indian Alumina Refineries and their Possible Solutions

India is endowed with a vast bauxite reserve totalling 3037 million tons,more than 87% of which is deemed fit for the production of metallurgical grade alumina by the Bayer 's process. In spite of having such a vast bauxite reserve, the country 's alumina production is very meagre and poised for augmentation in the near future. Also, the existing alumina plants except for Nalco, which has been set-up in the eighties , all the other existing plants are quite old and require modernisation and capacity expansion. With further additional capacities, may it be new green field plants or brown field expansions, there would be an increasing concern mainly for bauxite residue disposal, the working environment and nearby surroundings. The working environment in the alumina plant is critical due to the handling of corrosive chemicals, toxic fumes, air borne emissions, noise hazards and require necessary safety monitoring system. Based on plant operation experience and critical literature survey it is thought that the environmental measures possible under the Indian conditions would match even the best available in the alumina industry abroad, so that there will be a very little negative impact. This paper attempts to bring out the possible areas of concern with measures available and comparison of those with the best possible under the Indian conditions. The overall assessment of impact on the environment including the social , cultural and economic would be highly beneficial to the project planners, local community and the country in genera