A comprehensive model of a novel rotating spool compressor

A comprehensive simulation model of a novel rotating spool compressor is presented. The spool compressor provides a new rotary compression mechanism with easily manufactured components. A detailed analytical geometry model of the spool compressor is presented, which includes the geometry of the vane. This geometry model is included in an overall comprehensive compressor model that includes sub-models for friction, leakage, and heat transfer. The results of the comprehensive model were validated using experimental data from a prototype compressor. The prototype compressor has an overall displacement of 23.9 cm³, and was operated using R410A as the working fluid. The model predicts the volumetric efficiency, discharge temperature, and shaft power of the prototype compressor to within 3.13% MAE, 16.5 K and ?13.2 W average deviation, respectively. The trends and spread in the data indicate that additional effort should be focused on the operation of the active sealing elements within the compressor.     

Inhibitors of inducible NO synthase expression: total synthesis of (S)-curvularin and its ring homologues

(S)-Curvularin and its 13-, 14-, and 16-membered lactone homologues were synthesized through a uniform strategy in which a Kochi oxidative decarboxylation and ring-closing metathesis reactions constitute the key processes. In the evaluation of the anti-inflammatory effects of the synthesized compounds in assays using cells stably transfected with a human iNOS promoter-luciferase reporter gene construct, the 14- and 16-membered homologues showed a slightly higher inhibitory effect towards iNOS promoter activity than curvularin itself. However, the larger ring homologues also exhibited higher cytotoxicity, manifest in downregulated eNOS promoter activity. In contrast, the di-O-acetyl and 4-chloro derivatives of (S)-curvularin showed higher inhibitory efficiency towards induction of the iNOS promoter and less negative effect on eNOS promoter activity than curvularin.     

Antibacterial activity of cationically modified cotton fabric with carboxymethyl chitosan

A water‐soluble carboxymethyl chitosan was prepared with a view to develop a multifunctional finish on cotton. Carboxymethyl chitosan (CMCTS) was synthesized by chemical reaction of chitosan with monochloroacetic acid under alkaline condition. The water soluble CMCTS was applied to cationized cotton with different concentrations. The treated fabrics were characterized through monitoring the textile physical properties and for the antibacterial activity against Escherichia coli DSMZ 498 and Micrococcus luteus ATCC 9341. The results obtained show that the physical properties of the treated fabrics are improved by increasing the CMCTS concentration, as well as the antibacterial activity. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Solidification behaviour of binary sitosteryl esters mixtures

Phytosterol esters are known for their blood cholesterol lowering effect and have consequently been incorporated into vegetable oil table-spread products. In furtherance to gaining knowledge about these materials in a fat-blend environment, the current work describes the phase-diagram based thermal characteristics of a series of β-sitosterol alkyl-ester homologues prepared as binary mixtures and observed using differential scanning calorimetry. A scanning speed of 10 K min⁻¹ was chosen and, whilst not representing true equilibrium conditions, was more indicative of the likely dynamic melting or cooling conditions found in a fat-blend product during processing. The thermal behaviours presented reflect therefore this concept. Long-chain saturated esters showed ideal solubility behaviour of immiscible solids. In contrast, the shorter-chain homologues produced complex and dynamic phase behaviours, including some mesophase development. In all cases, supercooling was observed on cooling due to retarded crystallisation, which could equally result in two crystal conformations, depending on the actual composition.     

超临界流体染色技术的过去、现在和将来(一)

介绍了超临界CO2染色技术在世界范围的发展过程及其优于水染色的特点。阐述了超临界CO2对纤维性能的影响，诸如润滑效果CO2吸附、结晶、收缩和热机械性能，超临界CO2对纤维的玻璃化温度和有效温度以及对纤维损伤的影响。另一重要问题是在超临界CO2中纤维与染料之间的平衡分布和影响染料溶解性的参数。文中给出了涤纶纤维的染色步骤、设备和最佳工艺参数，然而天然纤维的染色仍是一个问题。通过浸渍溶胀剂和交联剂，或在染色前对纤维改性、添加极性共溶剂，可以提高分散染料的染色性，所有这些方法增加了工艺步骤和设备清洗，若使用有机溶剂则将大大提高机器成本，采用活性分散染料可以避免这种情况。含乙烯砜基团的染料主要适宜于羊毛和聚酰胺纤维的超临界CO2染色，而对于纤维素纤维迄今尚未开发可行的解决方法。预计在不久的将来建造工业化规模的染色设备，努力实现超临界CO2染色技术的经济效益。     

The Dyeing of Polyolefin Fibers in Supercritical Carbon Dioxide. Part I: Thermo-mechanical Properties of Polyolefin Fibers after Treatment in CO2 under Dyeing Conditions

The viscoelastic properties of gel-spun polyethylene (PE) and polypropylene (PP) fibers after treatment in supercritical CO₂, at 280 bar were examined to determine the optimum conditions for dyeing without causing fiber damage. Above 100°C, a greater amount of shrinkage, mainly of PP fiber, is observed in CO₂, than in air at 1 bar. Under isothermal conditions at 100°C, pressure-dependent on-line measurements of a PP-fiber monofli up to 280 bar show that shrinkage becomes very considerable at low pressures of only 10 bar. In comparison with isobaric conditions at 280 bar, shrinkage starts at temperatures above 60°C and is greatest between 90 and 100°C. In both cases, the degree of shrinkage is 11–12%. The value of F._max on the stress—strain diagrams of all fibers tested is not influenced by the treatment in CO₂, up to 120°C. However, the elongation increases only for polyolefins with a lower degree of crystallinity to the extent of about 15% for the PP monofil and 13% for the LM-PE fiber. Furthermore, CO₂, is able to penetrate into the hydrophobic PE and PP fibers and acts as a quasi-impurity, reducing the melting point (mp) of LM-PE fibers by between 5 and 7^°C and that of PP monofli by 9 and 22°C at 50 and 280 bar, respectively. This was observed by differential-dynamic-heat-flow calorimetric measurements in CO₂. The decrease in mp of the highly crystalline HM-PE fiber is only 2°C because the diffusion of CO₂ into the fiber is extremely slow.     

Giant Magnetoelectric Effect in Thin‐Film Composites

Highly sensitive AC magnetic field sensors are presented using magnetoelectric composites consisting of magnetostrictive and piezoelectric phases. They are offering passive nature, high sensitivity, large effect enhancement at mechanical resonance, and large linear dynamic range. Thin‐film magnetoelectric 2‐2 composites benefit from perfect coupling between the piezoelectric and magnetostrictive phases and from the reduction in size which is essential for high spatial resolution. Their design uses AlN and a plate capacitor or PZT with interdigital electrodes and magnetostrictive amorphous FeCoSiB single layers or exchanged biased multilayers. At mechanical resonance and depending on the geometry, extremely high ME coefficients of up to 9.7 kV/cm Oe in air and up to 19 kV/cm Oe under vacuum were obtained. To avoid external DC magnetic bias fields, composites consisting of exchanged biased multilayers serving as the magnetostrictive component with a maximum magnetoelectric coefficient at zero magnetic bias field are employed. Furthermore, the anisotropic response of these exchanged biased composites can be utilized for three‐dimensional vector field sensing. Sensitivity and noise of the sensors revealed limits of detection as good as to 2.3 pT/Hz^1/2 at mechanical resonance. Sensitivity between 0.1 and 1000 Hz outside resonance can be enhanced through frequency conversion using AC magnetic bias fields.