Ultrafast large-area micropattern generation in nonabsorbing polymer thin films by pulsed laser diffraction

An ultrafast, parallel, and beyond-the-master micropatterning technique for ultrathin (30-400 nm) nonabsorbing polymer films by diffraction of laser light through a 2D periodic aperture is reported. The redistribution of laser energy absorbed by the substrate causes self-organization of polymer thin films in the form of wrinklelike surface relief structures caused by localized melting and freezing of the thin film. Unlike conventional laser ablation and laser writing processes, low laser fluence is employed to only passively swell the polymer as a pre-ablative process without loss of material, and without absorption/reaction with incident radiation. Self-organization in the thin polymer film, aided by the diffraction pattern, produces microstructures made up of thin raised lines. These regular microstructures have far more complex morphologies than the mask geometry and very narrow line widths that can be an order of magnitude smaller than the openings in the mask. The microstructure morphology is easily modulated by changing the film thickness, aperture size, and geometry, and by changing the diffraction pattern.     

如何保证云计算的安全

云计算能给人们带来许多实际的好处,但安全是必须要保证的前提。虚拟数据中心必须获得虚拟安全系统的支持,而后者又必须得到虚拟测试系统和测试方法的验证 随着过去10年里200多家云提供商的出现,云计算迅速崛起,为成千上万个公司和组织带来了成本和生产力方面的好处。但是,关于云安全的种种疑问却表明,联网和计算能力的增长已经超过了保护云不受计算机攻击的技术的发展。     

Evaluation of Mass Transfer Mechanisms During Osmotic Treatment of Plant Materials

ABSTRACT: The proportion of intact, damaged, and ruptured (non-intact) cells (Zp) due to osmotic stress during osmotic treatment of potato was monitored using electrophysical measurement based on electrical impedance analysis. Osmotic stress on potato cell culture made cell membranes shrink thereby damaging the cells. The proportion of the ruptured and shrunk cells within the samples increased with the increase in concentration of solute in the osmotic solution. The osmotic removal of water from thin potato slices started at a critical osmotic pressure. Once the critical osmotic pressure was exceeded, mass transfer was rapid and the cells lost substantial amounts of water due to rupture of cell membranes.     

Topical Neck Cooling Prolongs Survival of Rats with Intra-Abdominal Feculent Sepsis by Activation of the Vagus Nerve

Global hypothermia prolongs survival in rats with intraabdominal feculent sepsis by inhibiting inflammatory responses. We hypothesized that topical neck cooling (TNC) has similar benefits. Septic shock was induced by cecal ligation and incision (CLI) in Sprague Dawley rats. Rats were randomized to sham laparotomy, control with CLI, CLI with TNC, or vagotomy at the gastroesophageal junction before CLI and TNC. Two more groups underwent peritoneal washout with and without TNC two hours after CLI. TNC significantly lowered neck skin temperature (16.7 ± 1.4 vs. 30.5 ± 0.6 °C, p < 0.05) while maintaining core body normothermia. TNC rats recovered from anesthesia 70 min earlier than the control (p < 0.05). Three hours following CLI, the control and vagotomy with TNC groups had significantly more splenic contraction, fewer circulating leukocytes and higher plasma IL-1β, IL-10 and TNF-α levels than TNC rats (p < 0.05). TNC prolonged survival duration after CLI by a median of four hours vs. control (p < 0.05), but no benefit was seen if vagotomy preceded TNC. Peritoneal washout alone increased survival by 3 h (9.2 (7.8–10.5) h). Survival duration increased dramatically with TNC preceding washout, to a 56% survival rate (>10 days). TNC significantly prolonged the survival of rats with severe intraabdominal sepsis by inhibiting systemic proinflammatory responses by activating vagal anti-inflammatory pathways.     

Photoelectrochemical analysis of band gap modulated TiO2 for photocatalytic water splitting

In this study the photocatalysis efficiency of titania (TiO₂) is increased by conjugating it with folic acid (FA) molecules through a silane linker (APTMS) layer. Electrochemical testing demonstrated higher negative open circuit potential (OCP) in surface engineered TiO₂ as compared to TiO₂ indicating higher Schottky barrier leading to suppressed electron–hole pair recombination. The photocurrent density under no bias conditions demonstrated 55% increase in modified titania due to lower band gap and suppressed electron hole pair recombination. The mechanism behind higher photocatalytic properties of surface engineered TiO₂ was derived using density functional theory (DFT).     

Study on the thermal decomposition of NaBH4 catalyzed by ZrCl4

The catalytic effect of zirconium tetrachloride (ZrCl₄) on the thermal dehydrogenation of NaBH₄ has been studied. The ZrCl₄ reduced to ZrCl₂ and metallic zirconium which exhibit the high catalytic activity during thermal dehydrogenation. The activation energy corresponding to dehydrogenation of NaBH₄ is remarkably reduced to 180 kJ/mol in the presence of a catalyst as compared to pure-NaBH₄ which was found to be 275 kJ/mol under the similar experimental conditions. The reduced activation energy leads to decreased onset dehydrogenation temperature (<300 °C). A substantial amount of sodium remained at the end of the dehydrogenation of catalyzed sample. The low-temperature dehydrogenation of catalyzed NaBH₄ could be useful to manage the evaporation of sodium metal.     

Optimization of enzymatic degradation of coconut residue

Enzymatic degradation of coconut residue has been optimised by response surface methodology to increase the yield of coconut milk. The study of complex interaction among pH, enzyme concentration, temperature, water ratio and time and identification of the optimal combination have been carried out using central composite rotatable design (CCRD) experiments. The result showed about 93% degradation of degradable solids could be obtained at pH 4·12, enzyme concentration 4·87%, temperature 65°C, water ratio 1·68 and time 9·98 h. Experimental results are in good agreement with the predicted values. © 1998 SCI.     

Experimental and numerical investigation of heat transfer in Li‐ion battery pack of a hoverboard

Li‐ion cells are used for energy storage and conversion in electric vehicles and a variety of consumer devices such as hoverboards. Performance and safety of such devices are severely affected by overheating of Li‐ion cells in aggressive operating conditions. Multiple recent fires and accidents in hoverboards are known to have originated in the battery pack of the hoverboard. While thermal analysis and measurements have been carried out extensively on large battery packs for electric vehicles, there is relatively lesser research on smaller devices such as hoverboards, where the extremely limited thermal management design space and the critical importance of user safety result in severe thermal management challenges. This paper presents experimental measurements and numerical analysis of a novel approach for thermal management of the battery pack of a hoverboard. Measurements indicate that temperature rise in cells in the pack can be as large as 30°C at 4C discharge rate, which, although unlikely to be a standard discharge rate, may result from a malfunction or accident. A novel thermal management approach is investigated, wherein careful utilization of air flow generated by hoverboard motion is shown to result in significant temperature reduction. Measurements also indicate the key role of the metal housing around the battery pack in thermal management. Measurements are found to be in good agreement with finite element simulations, which indicate that the battery pack can be cooled as effectively in presence of a perforated metal casing as without the casing at all. Experimental data and simulation model presented here offer critical insights into the design of hoverboard thermal management and may result in safer, high performance hoverboard battery packs.