常压非热等离子体源及其在纺织整理中的应用

综述了常压介电屏蔽放电（DBD）产生的非热等离子体在纺织整理中的应用。描述了DBD在常压织物整理和等离子体化学中的许多潜在优势。DBD（无声放电）是一种非热等离子体放电,在较宽的温度和压力范围内操作简便。常压下,许多独立的细电流丝之间会发生电击穿,这些短暂的带有电子能量的微放电具有瞬时高压辉光放电性质,非常适合背景气体原子或分子的激发和离解。     

Mutator phenotype induced by aberrant replication

We have identified thermosensitive mutants of five Schizosaccharomyces pombe replication proteins that have a mutator phenotype at their semipermissive temperatures. Allele-specific mutants of DNA polymerase delta (poldelta) and mutants of Polalpha, two Poldelta subunits, and ligase exhibited increased rates of deletion of sequences flanked by short direct repeats. Deletion of rad2(+), which encodes a nuclease involved in processing Okazaki fragments, caused an increased rate of duplication of sequences flanked by short direct repeats. The deletion mutation rates of all the thermosensitive replication mutators decreased in a rad2Delta background, suggesting that deletion formation requires Rad2 function. The duplication mutation rate of rad2Delta was also reduced in a thermosensitive polymerase background, but not in a ligase mutator background, which suggests that formation of duplication mutations requires normal DNA polymerization. Thus, although the deletion and duplication mutator phenotypes are distinct, their mutational mechanisms are interdependent. The deletion and duplication replication mutators all exhibited decreased viability in combination with deletion of a checkpoint Rad protein, Rad26. Interestingly, deletion of Cds1, a protein kinase functioning in a checkpoint Rad-mediated reversible S-phase arrest pathway, decreased the viability and exacerbated the mutation rate only in the thermosensitive deletion replication mutators but had no effect on rad2Delta. These findings suggest that aberrant replication caused by allele-specific mutations of these replication proteins can accumulate potentially mutagenic DNA structures. The checkpoint Rad-mediated pathways monitor and signal the aberrant replication in both the deletion and duplication mutators, while Cds1 mediates recovery from aberrant replication and prevents formation of deletion mutations specifically in the thermosensitive deletion replication mutators.     

High-power Ar-N2transfer laser at 3577 Å

A peak laser power of 0.5 MW with an estimated efficiency of 0.2 percent has been obtained at 3577 Å from a mixture of 92 psia Ar and 8 psia N2which was excited by anE-beam of 400 A/cm²at 1.3 MeV in a 20-ns pulse. A saturation intensity of ∼100 kW/cm²was deduced and a beam divergence of 10 mrad was measured from the laser having a 10-cm gain length.     

Bubble size distribution in a flotation column

The bubbles that were generated in a flotation column were measured. The bubble size distributions were obtained both for air-water and air-water-coal systems. The size distribution pattern was fitted to different equations. It was found that the bubble size distribution in both the flotation and cleaning zones follows the Rosin-Rommler equation used to describe the particle size distribution in crushing. This study indicates that bubbles in the cleaning zone are always larger than those of the flotation zone and finer bubbles are generated when a mixture of frothers is used instead of individual frothers.     

Baeyer-Villiger rearrangement catalysed by titanium silicate molecular sieve (TS-1)/H2O2 system

Titanium silicate molecular sieve TS-1 has been found to be an efficient catalyst for Baeyer-Villiger (BV) oxidation of cyclic and aromatic ketones under triphase conditions (solid catalyst along with two immiscible liquid reactants in the absence of any cosolvent), using dilute H₂O₂. Reactions studied are the oxidation of cyclohexanone and acetophenone. Whereas in the case of cyclohexane,-caprolactone, a BV product along with hydroxy and diketones is formed, in the case of acetophenone, phenyl acetate, a BV product along witho- andp-hydroxyacetophenone is formed. The acidic nature of titanium peroxo species, stabilised by water, is proposed to be responsible for such reactions under triphasic reaction conditions.On leave from: Catalysis Division, Indian Institute of Petroleum, Dehradun 248 005, India.     

Fibers spun from blends of different molecular weights of polypropylene

Fibers spun from blends of small percentage of plastic grade polypropylene (HMPP) with fiber grade polypropylene (PP) are studied for drawing behavior. A factorial design of experiment is used for a two-stage drawing process with variables, such as percent of HMPP component, first stage draw ratio and temperature, and second stage temperature. Optimization is carried out for breaking stress and modulus of drawn filaments. Breaking stress of up to 0.74 GPa and initial modulus of 7.34 GPa is possible by such an optimization process. These properties are observed for 6% HMPP blend composition. Heat setting of drawn filaments show little changes up to 140°C heat-setting temperature. Large scale structural changes with rapid drop in mechanical properties is observed for 150-160°C heat-set samples.     

Hydrothermal transformation of a layered aluminophosphate into a mesoporous structure

A new mesoporous aluminophosphate (AlPO₄) has been synthesized through hydrothermal transformation of a lamellar mesostructured aluminophosphate prepared in the presence of a neutral surfactant dodecylamine (DDA) under mild alkaline pH conditions and using water–ethanol mixture as the synthesis medium. Post-synthesis hydrothermal treatment was carried out at 448 K for 72 h in the presence of dilute aqueous phosphoric acid, which results this phase transformation. Lamellar and mesoporous phases of these samples were revealed from powder X-ray diffraction, SEM-EDS, transmission electron microscopic image analysis, ³¹P MAS NMR a FT IR spectroscopic studies and thermal analysis. N₂ sorption studies revealed the existence of pores with dimension of small mesopores after H₃PO₄ treatment. Pillaring of the interlayers through PO₄ units during post-synthesis hydrothermal treatment could be responsible for the transformation of lamellar to mesoporous phase.     

Fatigue Fracture of a Compressor Disc of an Aeroengine

There was an accident to a single engine aircraft. From the eye and ear witness accounts, it was established that the accident occurred because of engine failure. After preliminary examination of the wreckage of the crashed engine, a few suspected components were identified for detailed laboratory investigation. The objective was to establish the primary failure in the engine. While majority of the engine components submitted for laboratory analysis showed secondary damages due to either crash impact forces or post-accident fire, the fracture pattern in one of the compressor disks was different from other components of the engine. Fractographic study revealed that the failure of the disk was by fatigue mechanism. Subsequent investigation showed that the fatigue fracture of the compressor disk was the first in the chain of events that led to the engine failure. This finding was further substantiated through fracture mechanics calculations.     

Selective adsorption and release of cationic organic dye molecules on mesoporous borosilicates

Mesoporous materials can play a pivotal role as a host material for delivery application to a specific part of a system. In this work we explore the selective adsorption and release of cationic organic dye molecules such as safranine T (ST) and malachite green (MG) on mesoporous borosilicate materials. The mesoporous silica SBA-15 and borosilicate materials (MBS) were prepared using non-ionic surfactant Pluronic P123 as template via evaporation induced self-assembly (EISA) method. After template removal the materials show high surface areas and in some cases ordered mesopores of dimensions ca. 6–7 nm. High surface area, mesoporosity and the presence of heteroatom (boron) help this mesoporous borosilicate material to adsorb high amount of cationic dye molecules at its surface from the respective aqueous solutions. Furthermore, the mesoporous borosilicate samples containing higher percentage adsorbed dyes show excellent release of ST or MG dye in simulated body fluid (SBF) solution at physiological pH = 7.4 and temperature 310 K. The adsorption and release efficiency of mesoporous borosilicate samples are compared with reference boron-free mesoporous pure silica material to understand the nature of adsorbate–adsorbent interaction at the surfaces.