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61.
A statistical approach, response surface methodology (RSM), was used to study the production of extracellular protease fromBacillus sp., which has properties of immense industrial importance. The most influential parameters for protease production obtained
through the method of testing the parameters one at a time were starch, soybean meal, CaCl2, agitation rate, and inoculum density. This method resulted in the production of 2543 U/mL of protease in 48 h fromBacillus sp. Based on these results, face-centered central composite design falling under RSM was employed to further enhance protease
activity. The interactive effect of the most influential parameters resulted in a 1.50-fold increase in protease production,
yielding 3746 U/mL in 48 h. Analysis of variance showed the adequacy of the model and verification experiments confirmed its
validity. On subsequent scale-up in a 30-L bioreactor using conditions optimized through RSM, 3978 U/mL of protease was produced
in 18 h. This clearly indicated that the model remained valid even on a large scale. RSM is a quick process for optimization
of a large number of variables and provides profound insight into the interactive effect of various parameters involved in
protease production. 相似文献
62.
Díaz RI Regourd J Santacroce PV Davis JT Jakeman DL Thompson A 《Chemical communications (Cambridge, England)》2007,(26):2701-2703
A new class of prodigiosenes with stability-enhancing functionalities appended to the C-ring were found to transport chloride anions through liposomal membranes, as well as to induce copper-mediated DNA cleavage. 相似文献
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65.
Ryu G Huang J Hofmann O Walshe CA Sze JY McClean GD Mosley A Rattle SJ deMello JC deMello AJ Bradley DD 《Lab on a chip》2011,11(9):1664-1670
We demonstrate a compact, low cost and practical fluorescence detection system for lab-on-a-chip applications. The system comprises a commercially available InGaN light emitting diode (501 nm) as light source, an organic or silicon photodiode detector, absorptive dye coated colour filters and linear and reflective polarisers. An injection moulded polystyrene microfluidic chip is used as the platform for fluorescence immunoassays for cardiac markers myoglobin and CK-MB. The optical limit of detection (LOD) is measured using a TransFluoSphere? suspension at 5.6 × 10(4) beads μl(-1) which can be equated to ~3 nM fluorescein equivalent concentration. The LOD for the human plasma immunoassays is measured as 1.5 ng ml(-1) for both myoglobin and CK-MB. 相似文献
66.
Sie Tiong Ha Teck Leong Lee Siew Ling Lee Guan Yeow Yeap Yip Foo Win Siew Teng Ong 《中国化学快报》2012,23(2):177-180
A homologous series of azomethine esters,4-n-alkanoyloxybenzylidene-4’-bromoanilines possessing even number of carbon atoms at the terminal alkanoyloxy chain(Cn-1H2n-1COO- n = 8,10,12,14,16,18) was synthesized and characterized.Whilst n-octanoyloxy to n-dodecanoyloxy derivatives exhibited enantiotropic smectic A and smectic B phases,n-tetradecanoyloxy to n-octadecanoyloxy derivatives possessed enantiotropic smectic A and monotropic smectic B properties.n-Decanoyloxy derivatives demonstrated the optimum exhibition for both smectic A and smectic B phases.It was found that the length of terminal alkanoyloxy chain has an influence on mesomorphic properties. 相似文献
67.
This paper reports a novel method for the rapid determination of vitamin B(12) concentration in a continuous-flow lab-on-a-chip system. This new method is based on luminol-peroxide chemiluminescence (CL) assays for the detection of cobalt(II) ions in vitamin B(12) molecules. The lab-on-a-chip device consisted of two passive micromixers acting as microreactors and a double spiral microchannel network serving as an optical detection region. This system could operate in two modes. In the first mode, samples are acidified and evaluated directly in the microchip. In the second mode, samples are treated externally by acidification prior to detection in the microchip. In the first mode, the linear range obtained was between 1.00 ng ml(-1) to 10 μg ml(-1), R(2) = 0.996, with a relative standard deviation (RSD) of 1.23 to 2.31% (n = 5) and a limit of detection (lod) of 0.368 pg ml(-1). The minimum sample volume required and the analytical time were 30 μl and 3.6 s, respectively. In the second mode, the linear range obtained was between 0.10 ng ml(-1) to 10 μg ml(-1), R(2) = 0.994, with the RSD of 0.90 to 2.32% (n = 6) and a lod of 0.576 pg ml(-1). The minimum sample and the analytical time required were 50 μl and 6 s, respectively. The lab on a chip working in mode II was successfully used for the determination of vitamin B(12) concentrations in nutritional supplemental tablets and hen egg yolks. 相似文献
68.
T Fukushima S Horike H Kobayashi M Tsujimoto S Isoda ML Foo Y Kubota M Takata S Kitagawa 《Journal of the American Chemical Society》2012,134(32):13341-13347
The mesoscale design of domain assembly is crucial for controlling the bulk properties of solids. Herein, we propose a modular design of domain assembly in porous coordination polymer crystals via exquisite control of the kinetics of the crystal formation process. Employing precursors of comparable chemical reactivity affords the preparation of homogeneous solid-solution type crystals. Employing precursors of distinct chemical reactivity affords the preparation of heterogeneous phase separated crystals. We have utilized this reactivity-directed crystallization process for the facile synthesis of mesoscale architecture which are either solid-solution or phase-separated type crystals. This approach can be also adapted to ternary phase-separated type crystals from one-pot reaction. Phase-separated type frameworks possess unique gas adsorption properties that are not observed in single-phasic compounds. The results shed light on the importance of crystal formation kinetics for control of mesoscale domains in order to create porous solids with unique cooperative functionality. 相似文献
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A fast automated system for rapid electrophoretic separations in short conventional capillaries employing contactless conductivity detection is presented. The instrument is based on pneumatic pressurization and does not require a conventional pump. The required pressures and flow rates for the different steps of the injection and flushing processes are produced with the help of two flow restrictors. The device is implemented on a microfluidic breadboard with dimensions of ca. 13 × 20 cm and employs miniature valves. Nine inorganic cations, namely NH4+, K+, Na+, Ca2+, Mg2+, Mn2+, Sr2+, Li+, and Ba2+, could be separated in a capillary of 10 μm inner diameter and 6 cm effective length within 25 s. Following a reduction of the effective length to 4 cm, still five inorganic cations could be separated in a time span of 12 s. The repeatability of peak areas was better than 3.1 % and limits of detection between 3.5 and 5.5 μM were achieved. 相似文献