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71.
H. Y. Lew 《Journal of the American Oil Chemists' Society》1964,41(4):297-300
Long chain alkyldimethylamine oxides in detergent mixtures have not only been difficult to determine but also interfere with
anionic active analysis by the usual quaternary titration with methylene blue indicator. Titration methods have been devised
for the quantitative analysis of amine oxides and anionic actives in the presence of each other and low molecular wt sulfon-ates.
A gas Chromatographic method has also been developed for determining molecular distribution in alkyldimethylamine oxide mixtures.
Analytical data are presented for a series of alkyldimethylamine oxides of different mol wt and for several experimental detergent
formulations. The titration method is rapid and amenable to both solid and liquid detergent formulations.
Presented at the AOCS Meeting in Minneapolis, 1963. 相似文献
72.
Polypropylene was degraded by injection of a free-radical initiator during extrusion. Molecular weight distribution, molecular weight averages, and melt flow index were measured to see the effect of initiator concentration (0.00 to 0.04 wt%), temperature (200 and 220°C), and screw rpm (31 and 44). Initiator concentration was the most significant variable. In all cases, increased initiator concentration degraded the high molecular weight tail of the polypropylene and narrowed the molecular weight distribution. Melt flow index varied linearly with initiator concentration beyond 0.01 wt% initiator. Reaction temperature had no effect on the measured properties of the extrudate. This was attributed to the minimum residence time in the extruder being sufficient for all degradation reactions to be completed. It also implied that the same reactions occurred at both temperatures. Increased screw rpm slightly increased molecular weight. No interaction among initiator concentration, temperature, and screw rpm was observed. 相似文献
73.
Five different types of calibration curve currently used in size exclusion chromatography-differential viscometer (SEC–DV) systems were identified and their use summarized. A simple method of deriving weighting factors for fitting local intrinsic viscosity calibration curves was shown to greatly improve the precision of calculated molecular weight distributions. The problem of reliably extrapolating the fitted curves to allow for differences in sensitivity among detectors has yet to be examined. With regard to Mark—Houwink constants, a method of fitting data from the SEC–DV system to obtain more statistically sound values was derived. For the data used here, the new method involves fitting a plot of logarithm of the local intrinsic viscosity of the sample vs. logarithm of the universal calibration curve parameter, Ji. Results for the data obtained appeared only slightly more precise than those for the traditional method. However, the new method promises improved reliability. © 1993 John Wiley & Sons, Inc. 相似文献
74.
The conversion of3H-squalene to sterols by rat liver microsomes and cytosol was inhibited by individual rat and human plasma lipoproteins at
various concentrations. This inhibition was also observed with added human high density apolipoprotein, but triglycerides,
cholesterol or cholesteryl esters had no inhibitory effects. Lipoproteins and apo high density lipoprotein (HDL) were demonstrated
to bind3H-squalene in vitro. The binding of3H-squalene by apo HDL could be reversed by increasing concentration of liver cytosol containing sterol carrier protein. 相似文献
75.
Tianyi Na Ke Shao Jing Zhu Zhongguo Liu Hongcheng Sun Christopher M. Lew Zhuoqi Zhang Gang Zhang 《Polymer》2012,53(20):4413-4419
A novel series of naphthalene-based poly(arylene ether ketone) copolymers containing methoxy groups and hexafluoroisopropylidene diphenyl moieties (6F-MNPAEKs) were successfully synthesized by aromatic nucleophilic polycondensation. Chain-type fluorinated and sulfonated naphthalene-based poly(arylene ether ketone) copolymers (6F-SNPAEKs) were subsequently synthesized by demethylation and sulfobutylation. The chemical structures of 6F-SNPAEKs were confirmed by 1H NMR. The 6F-SNPAEKs in acid form showed excellent thermal stability at elevated temperatures. The 6F-SNPAEK membranes were easily obtained by solution casting and properties for fuel cells were investigated in detail. The water uptake, swelling ratio and proton conductivity increased with degree of sulfonation (DS) and temperature. 6F-SNPAEK-90 showed the highest conductivity of 0.181 S cm?1 at 80 °C. The methanol permeability of the membranes was in the range of 0.238–6.49 × 10?7 cm2 s?1, compared to 1.55 × 10?6 cm2 s?1 for Nafion 117. The membranes also showed excellent mechanical properties: the elongation at break was greater than 15%. These results indicate that the 6F-SNPAEK membranes are a promising candidate for use in direct methanol fuel cell (DMFC) applications. 相似文献
76.
C H Lew J Y Hu L F Song L Y Lee S L Ong W J Ng H Seah 《Water science and technology》2005,51(6-7):455-463
An integrated membrane process (IMP) comprising a membrane bioreactor (MBR) and a reverse osmosis (RO) process was developed for water reclamation. Wastewater was treated by an MBR operated at a sludge retention time (SRT) of 20 days and a hydraulic retention time (HRT) of 5.5 h. The IMP had an overall recovery efficiency of 80%. A unique feature of the IMP was the recycling of a fraction of RO concentrate back to the MBR. Experimental results revealed that a portion of the slow- and hard-to-degrade organic constituents in the recycle stream could be degraded by an acclimated biomass leading to an improved MBR treatment efficiency. Although recycling concentrated constituents could impose an inhibitory effect on the biomass and suppress their respiratory activities, results obtained suggested that operating MBR (in the novel IMP) at an F/M ratio below 0.03 g TOC/g VSS.day could yield an effluent quality comparable to that achievable without concentrate recycling. It is noted in this study that the novel IMP could achieve an average overall TOC removal efficiency of 88.940% and it consistently produced product water usable for high value reuse applications. 相似文献
77.
Jong-Lick Lin Jiun-Shang Lew 《Power Electronics, IEEE Transactions on》1999,14(5):793-802
Robust controller design for a series resonant power converter is presented when load variation and unregulated input line voltage perturbation are taken into consideration. The perturbation of unregulated line voltage is treated as an exogenous disturbance and the load variation as a structured uncertainty of the converter. An averaged model, including disturbance and model uncertainty, is then derived. Two kinds of μ synthesis-D-K and μ-K iteration schemes-are applied to design robust controllers to diminish the susceptibility of the regulated voltage to perturbations of load variation and unregulated line voltage. In addition, a classical controller is also designed for performance comparison. Finally, simulations and experimental results are presented to verify the feasibility of the robust control theory 相似文献
78.
79.
Yu Liu Yanming Guo Theodoros Georgiou Michael S. Lew 《Multimedia Tools and Applications》2018,77(22):29407-29434
In recent years, deep learning has been successfully applied to diverse multimedia research areas, with the aim of learning powerful and informative representations for a variety of visual recognition tasks. In this work, we propose convolutional fusion networks (CFN) to integrate multi-level deep features and fuse a richer visual representation. Despite recent advances in deep fusion networks, they still have limitations due to expensive parameters and weak fusion modules. Instead, CFN uses 1 × 1 convolutional layers and global average pooling to generate side branches with few parameters, and employs a locally-connected fusion module, which can learn adaptive weights for different side branches and form a better fused feature. Specifically, we introduce three key components of the proposed CFN, and discuss its differences from other deep models. Moreover, we propose fully convolutional fusion networks (FCFN) that are an extension of CFN for pixel-level classification applied to several tasks, such as semantic segmentation and edge detection. Our experiments demonstrate that CFN (and FCFN) can achieve promising performance by consistent improvements for both image-level and pixel-level classification tasks, compared to a plain CNN. We release our codes on https://github.com/yuLiu24/CFN. Also, we make a live demo (goliath.liacs.nl) using a CFN model trained on the ImageNet dataset. 相似文献
80.
Diversity in metabolite production by Fusarium langsethiae, Fusarium poae, and Fusarium sporotrichioides 总被引:1,自引:0,他引:1
Thrane U Adler A Clasen PE Galvano F Langseth W Lew H Logrieco A Nielsen KF Ritieni A 《International journal of food microbiology》2004,95(3):257-266
The production of mycotoxins and other metabolites by 109 strains of Fusarium langsethiae, Fusarium poae, Fusarium sporotrichioides, and F. kyushuense was investigated independently in four laboratories by liquid or gas chromatography analyses of cultural extracts with UV diode array, electron capture, or mass spectrometric detection systems. From the compiled results, it was found that F. langsethiae consistently produced the trichothecenes diacetoxyscirpenol (DAS), T-2 toxin (T-2), HT-2 toxin (HT-2), and neosolaniol (NEO) and, to a lesser extent, some additional trichothecene derivatives. F. langsethiae also produced culmorins, chrysogine (CHRYS), aurofusarin (AUF), and enniatin (EN). F. sporotrichioides showed a metabolite profile similar to that of F. langsethiae, while F. poae had a different profile as 41 of 49 strains produced nivalenol (NIV) and other 8-keto trichothecenes, in addition to DAS and derivatives of this metabolite. Only a trace amount of NIV was detected from one strain of F. kyushuense. In summary, all the three core taxa of this joint study were found to produce trichothecenes. Fusarin C (F-C) was not detected from F. langsethiae, but it was produced by F. poae and F. sporotrichioides. Aurofusarin was only detected from a few strains of F. langsethiae, while nearly all strains of F. poae and F. sporotrichioides produced this compound. In contrast, chrysogine was not detected from F. poae, but was produced by the other two taxa. Production of enniatins was scattered among the three main taxa of this study, whereas beauvericin (BEA) was produced by many strains of F. poae and F. sporotrichioides. Only one odd strain of F. langsethiae (IBT 9959) produced beauvericin. However, the status of this strain is uncertain. By a polyphasic approach using species-specific metabolite profiles, the fruity odour of F. poae, and morphological observations, it was concluded that F. langsethiae, F. poae, and F. sporotrichioides should be regarded as three significant taxa at a species level. 相似文献