Robust nanopatterning by laser-induced dewetting of metal nanofilms

We have observed nanopattern formation with robust and controllable spatial ordering by laser-induced dewetting in nanoscopic metal films. Pattern evolution in Co film of thickness 1\leq h\leq8 nm on SiO_{2} was achieved under multiple pulse irradiation using a 9 ns pulse laser. Dewetting leads to the formation of cellular patterns which evolve into polygons that eventually break up into nanoparticles with monomodal size distribution and short range ordering in nearest-neighbour spacing R. Spatial ordering was attributed to a hydrodynamic thin film instability and resulted in a predictable variation of R and particle diameter D with h. The length scales R and D were found to be independent of the laser energy. These results suggest that spatially ordered metal nanoparticles can be robustly assembled by laser-induced dewetting

Inflammation-Induced Cell Proliferation Potentiates DNA Damage-Induced Mutations In Vivo

Mutations are a critical driver of cancer initiation. While extensive studies have focused on exposure-induced mutations, few studies have explored the importance of tissue physiology as a modulator of mutation susceptibility in vivo. Of particular interest is inflammation, a known cancer risk factor relevant to chronic inflammatory diseases and pathogen-induced inflammation. Here, we used the fluorescent yellow direct repeat (FYDR) mice that harbor a reporter to detect misalignments during homologous recombination (HR), an important class of mutations. FYDR mice were exposed to cerulein, a potent inducer of pancreatic inflammation. We show that inflammation induces DSBs (γH2AX foci) and that several days later there is an increase in cell proliferation. While isolated bouts of inflammation did not induce HR, overlap between inflammation-induced DNA damage and inflammation-induced cell proliferation induced HR significantly. To study exogenously-induced DNA damage, animals were exposed to methylnitrosourea, a model alkylating agent that creates DNA lesions relevant to both environmental exposures and cancer chemotherapy. We found that exposure to alkylation damage induces HR, and importantly, that inflammation-induced cell proliferation and alkylation induce HR in a synergistic fashion. Taken together, these results show that, during an acute bout of inflammation, there is a kinetic barrier separating DNA damage from cell proliferation that protects against mutations, and that inflammation-induced cell proliferation greatly potentiates exposure-induced mutations. These studies demonstrate a fundamental mechanism by which inflammation can act synergistically with DNA damage to induce mutations that drive cancer and cancer recurrence.Austrian Academy of Sciences (APART Fellowship)Singapore-MIT Alliance for Research and TechnologySingapore. National Research FoundationNational Institutes of Health (U.S.) (NIH R33-CA112151)National Institutes of Health (U.S.) (grant R01-CA079827

Investigation of pulsed laser induced dewetting in nanoscopic metal films

Hydrodynamic pattern formation (PF) and dewetting resulting from pulsed laser induced melting of nanoscopic metal films have been used to create spatially ordered metal nanoparticle arrays with monomodal size distribution on SiO_{\text{2}}/Si substrates. PF was investigated for film thickness h\leq7 nm < laser absorption depth \sim11 nm and different sets of laser parameters, including energy density E and the irradiation time, as measured by the number of pulses n. PF was only observed to occur for E\geq E_{m}, where E_{m} denotes the h-dependent threshold energy required to melt the film. Even at such small length scales, theoretical predictions for E_{m} obtained from a continuum-level lumped parameter heat transfer model for the film temperature, coupled with the 1-D transient heat equation for the substrate phase, were consistent with experimental observations provided that the thickness dependence of the reflectivity of the metal-substrate bilayer was incorporated into the analysis. The spacing between the nanoparticles and the particle diameter were found to increase as h^{2} and h^{5/3} respectively, which is consistent with the predictions of the thin film hydrodynamic (TFH) dewetting theory. These results suggest that fast thermal processing can lead to novel pattern formation, including quenching of a wide range of length scales and morphologies.Comment: 36 pages, 11 figures, 1 tabl

Antimicrofouling activity of Calotropis gigantea (L). R. Br.

1843-1848Milkweed or Calotropis gigantea belongs to Asclepiadaceae family having many curative principles in it. This present work aimed to study the phytochemicals prevailing in the Calotropis gigantea during the summer season by GCMS method and some of these phytochemicals tested against the collagen-binding matrix protein (4CN8) produced by the bacterial foulant through computational method. The result of GCMS analysis revealed that the prevalence of stigmasterol, alpha-amyrin, urs-12-en-24-oic acid, 3-oxo-, methyl ester, (+)-, 2(1H) Naphthalenone, 3,5,6,7,8, 8a-hexahydro-4, 8a-dimethyl-6-(1-ethylethenyl)-, Beta.-Amyrin, Bicyclo [3.1.1] heptane,2,6,6-trimethyl-, 1R-(1.alpha., 2.beta., 5.alpha.) -and 1H-Indene, 5-butyl-6-hexyloctahydro-, 2-[3-(4-tert-Butyl-phenoxy)-2-hydroxy-propylsulfanyl]-4,6-dimethyl-nicotinonitrile and cyclopropane carboxamide, 2-cyclopropyl-2-methyl-N-(1-cyclopropylethyl)- and pyridine-3-carboxamide, oxime, N-(2-trifluoro methyl phenyl). The in silico study exhibited that all the screened phytochemicals are having remarkably good interaction with the tested 4CN8 and possessing-8 to-11 Kcal/mol docking energy except pyridine-3-carboxamide, oxime, N-(2-trifluoromethylphenyl). Hence, the phytochemicals of Calotropis is a right candidate for further elaborate study to establish an eco-friendly alternative to existing toxic antifouling chemicals

Evaluation of biosorption potential of Gracilaria corticata for the removal of hexavalent chromium from aqueous solutions using response surface methodology

In this study, the biosorption of chromium (VI) on Gracilaria corticata biomass marine algae, was investigated in a batch and continious system. The influence of process parameters including sorbent size (0.176 - 1.503 mm), sorbent dosage (3 -7 g/l), temperature (25 - 45°C), contact time (2 - 10 hrs) and agitation speed (50 - 250 rpm) on the sorption of chromium (VI) were performed using a full factorial central composite design (CCD). This result of the studies indicates that the optimum biosorption conditions of sorbent size, sorbent dosage, temperature, contact time  and agitation speed were 0.5284 mm, 5.12 g, 35°C , 2 hours 58 minutes and 140 rpm, respectively. A higher value coefficient of determination R2 0.9799 evidenced the fitness of response surface methodology. The Langmuir and Freundlich isotherm models were applied to the equilibrium data. The Langmuir adsorption model was better than the other model. The maximum adsorption capacity of Gracilaria corticata was found to be 62.5 mg/g. The thermodynamic parameters like enthalpy (ΔH◦) and entropy (ΔS◦) were 34.57 (kJ/mol) and 0.1308 (kJ/mol K) respectively. The results showed that the biosorption of chromium (VI) by Gracilaria corticata is more endothermic and spontaneous

Megaesophagus in a Line of Transgenic Rats: A Model of Achalasia

Megaesophagus is defined as the abnormal enlargement or dilatation of the esophagus, characterized by a lack of normal contraction of the esophageal walls. This is called achalasia when associated with reduced or no relaxation of the lower esophageal sphincter (LES). To date, there are few naturally occurring models for this disease. A colony of transgenic (Pvrl3-Cre) rats presented with megaesophagus at 3 to 4 months of age; further breeding studies revealed a prevalence of 90% of transgene-positive animals having megaesophagus. Affected rats could be maintained on a total liquid diet long term and were shown to display the classic features of dilated esophagus, closed lower esophageal sphincter, and abnormal contractions on contrast radiography and fluoroscopy. Histologically, the findings of muscle degeneration, inflammation, and a reduced number of myenteric ganglia in the esophagus combined with ultrastructural lesions of muscle fiber disarray and mitochondrial changes in the striated muscle of these animals closely mimic that seen in the human condition. Muscle contractile studies looking at the response of the lower esophageal sphincter and fundus to electrical field stimulation, sodium nitroprusside, and L-nitro-L-arginine methyl ester also demonstrate the similarity between megaesophagus in the transgenic rats and patients with achalasia. No primary cause for megaesophagus was found, but the close parallel to the human form of the disease, as well as ease of care and manipulation of these rats, makes this a suitable model to better understand the etiology of achalasia as well as study new management and treatment options for this incurable condition.National Institutes of Health (U.S.) (Grant T32OD011141)National Institutes of Health (U.S.) (Grant P30ES002109

Self-similar shear-thickening behavior in CTAB/NaSal surfactant solutions

The effect of salt concentration Cs on the critical shear rate required for the onset of shear thickening and apparent relaxation time of the shear-thickened phase, has been investigated systematically for dilute CTAB/NaSal solutions. Experimental data suggest a self-similar behavior of the critical shear rate and relaxation time as functions of Cs. Specifically, the former ~ Cs^(-6) whereas the latter ~ Cs^(6) such that an effective Weissenberg number for the onset of the shear thickened phase is only weakly dependent on Cs. A procedure has been developed to collapse the apparent shear viscosity versus shear rate data obtained for various values of Cs into a single master curve. The effect of Cs on the elastic modulus and mesh size of the shear-induced gel phase for different surfactant concentrations is discussed. Experiments performed using different flow cells (Couette and cone-and-plate) show that the critical shear rate, relaxation time and the maximum viscosity attained are geometry-independent. The elastic modulus of the gel phase inferred indirectly by employing simplified hydrodynamic instability analysis of a sheared gel-fluid interface is in qualitative agreement with that predicted for an entangled phase of living polymers. A qualitative mechanism that combines the effect of Cs on average micelle length and Debye parameter with shear-induced configurational changes of rod-like micelles is proposed to rationalize the self-similarity of SIS formation.Comment: 27 pages, 17 figure

Wireless power transfer for Battery Management System in Electric Vehicle Applications

Wireless power transfer (WPT) using magnetic resonance is the technology which could set human free from than annoying wires. In fact, the WPT adopts the same basic theory which has already been developed for at least 30 years with the term inductive power transfer (IPT). WPT technology is developing rapidly in recent years. At kilowatts power level, the transfer distance increases from several millimeters to several hundred millimeters with a grid to load efficiency above 90%. &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; The advances make the WPT very attractive to the electric vehicle(EV) charging applications in both stationary and dynamic charging scenarios. This paper reviewed the technologies in the WPT area applicable to EV wireless charging. By introducing WPT in EVs, the obstacles of charging time, range and cost can be easily mitigated. Battery technology is no longer relevant in the mass market penetration of EVs. It is hoped that researcher could be encouraged by the state-of-the-art achievements, and push forward the further development of WPT as well as the expansion of EV

Impact of Ocean Acidification on Marker Enzymes in Asian Seabass Lates Calcarifer (Bloch)

Backgrounds: The influence of ocean acidification (OA) is particularly significant on calcifying organisms in marine environment. A possible explanation for acidification-induced changes in fish behaviour is that acidification interferes with marker enzymes in the liver, muscle and brain. Under a range of severe environmental circumstances, marine organisms can be susceptible to oxidative stress and results in the changes in the biochemical components which can be assessed to know the health status of organisms. Aim of the Works: The aim of this study is to observe the impact of ocean acidification in Asian seabass Lates calcarifer and to employ a large number of biomarker to discover distinct and unique patterns. For this the fingerlings of L. calcarifer were exposed to OA, in order to understand the changes in marker enzymes in liver, muscle and brain of L. calcarifer. Methodology: Fish fingerlings were exposed to OA condition with two different pH (7.8 and 7.5) for a period of 9 weeks in order to assess changes in biomarker. Acid phosphatase (ACP) and alkaline phosphatase (ALP), alanine transaminase (ALT), and aspartate transaminase activity (AST) were examined in the liver, brain and muscles of fish. Results: The Liver has considerably higher in ACP and ALP enzymes after 3 weeks of OA exposure. AST and ALT marker enzymes were induced in the brain at greater levels and in most cases, the entire marker enzymes in the liver, muscle and brain were concentration dependent and also the exposure period. The observed changes in marker enzymes which detected in the brain and liver tissues of L. calcarifer were statistically significant. Conclusions: The present study showed a significant association between the entire biomarkers tested in fish exposed to OA. Overall, the results indicate that brain and liver is the most vulnerable component to OA exposure when compared to muscles and brain it may be employed as a bioindicator of OA exposure