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11.
The bifunctional activities of α-amylase and pullulanase are found in the cloned recombinant amylopullulanase. It was encoded
in a 2.9-kb DNA fragment that was amplified using polymerase chain reaction from the chromosomal DNA of Thermoanaerobacter ethanolicus 39E. An estimated 109-kDa recombinant protein was obtained from the cloned gene under the prokaryotic expression system.
The optimum pH of the recombinant amylopullulanase was 6.0. The most stable pH for the α-amylase and pullulanase activity
was 5.5 and 5.0, respectively. The optimum temperature for the α-amylase activity was 90°C, while its most stable temperature
was 80°C. Regarding pullulanase activity, the optimum temperature and its most stable temperature were found to be 80 and
75°C, respectively. Pullulan was found to be the best substrate for the enzyme. The enzyme was activated and stabilized by
the presence of Ca2+, whereas EDTA, N-bromosuccinimide, and α-cyclodextrin inhibited its bifunctional activities. A malto-2–4-oligosac-charide was the major product
obtained from the enzymatic reaction on soluble starch, amylose, amylopectin, and glycogen. A single maltotriose product was
found in the pullulan hydrolysis reaction using this recombinant amylopullulanase. Kinetic analysis of the enzyme indicated
that the K
m
values of α-amylase and pullulanase were 1.38 and 3.79 mg/mL, respectively, while the V
max values were 39 and 98 μmol/(min · mg of protein), respectively. 相似文献
12.
A novel diagnostic method to characterize the flow patterns in an 80 mm-i.d. L-valve had been developed by using multi-resolution analysis (MRA) of wavelet transformation on the pressure fluctuation signals which were acquired from the standpipe and the horizontal part of L-valve. Parameters including the aeration rate, aeration positions, riser gas velocity and composition of binary particle mixture (194-μm and 937-μm sand particles) were used to investigate the relationship of performance of L-valve and its pressure fluctuations. By means of MRA, the original pressure fluctuations were divided into multi-scale signals. They were macro-scale, meso-scale and micro-scale successfully described the structures of gas–solid flow in the L-valve, such as the gas bubbles/slugs, dune-ripple flow, suspension particle flow, etc. 相似文献
13.
Yu‐Pin Wang Hsien‐Li Leu Tso‐Shen Lin Yu Wang Gene‐Hsiang Lee 《Acta Crystallographica. Section C, Structural Chemistry》2009,65(3):m131-m134
In the structures of each of the title compounds, [CrBr(C6H5O2)(NO)2], (I), and [CrBr(C12H9O)(NO)2], (II), one of the nitrosyl groups is located at a site away from the exocyclic carbonyl C atom of the cyclopentadienyl (Cp) ring, with twist angles of 174.5 (3) and 172.5 (1)°. The observed orientation is surprising, since the NO group is expected to be situated trans to an electron‐rich C atom in the ring. The organic carbonyl plane is turned away from the Cp ring plane by 5.6 (8) and 15.2 (3)°in (I) and (II), respectively. The exocyclic C—C bond in (I) is bent out of the Cp ring plane towards the Cr atom by 2.8 (3)°, but is coplanar with the Cp ring in (II); the angle is 0.1 (1)°. 相似文献
14.
On vortex shedding behind a circular disk 总被引:1,自引:0,他引:1
Abtract Experiments were performed for individual realizations of the vortex shedding process behind a circular disk at Reynolds
numbers of 103–105, at which periodic vortex shedding prevails in the wake. The phase differences regarding the individual vortex shedding structures
detected at multiple circumferential locations in the wake were obtained by analyzing the hot-wire signals with a conditional-sampling
scheme. The phase differences of vortex shedding detected at circumferential positions 90° apart show a wide scatter, but
the anti-phase character is largely preserved in the individual vortex shedding process as detected at circumferential locations
180° apart. The randomness of phase differences involved in the vortex shedding process is noted to be essential in order
to satisfy the axisymmetric property of the global flow.
Received: 4 April 19969/Accepted: 29 January 1997 相似文献
15.
In this study, well-ordered ZnO wrinkles were fabricated by sol–gel derived ZnO films via heat treatment at 400 °C for 2 h
with the assistance of polymethymethacrylate (PMMA) templates. PMMA templates with various patterns were employed to investigate
the effects of template geometries on arrangements of the formed ZnO wrinkles. The influence of thickness on the transformation
of the entire resulting structures of the spin-coated ZnO sol–gel films is discussed. With 2-dimensional arrangement of PMMA
patterns, more than two orientations of wrinkled ZnO can be induced in one template. By controlling the arrangement of PMMA
patterns and thickness of ZnO sol–gel films, specific circular, hexagonal, triangular and triangular-star complex structures
were produced due to the constrained shrinkage force of the ZnO films applied toward the PMMA side walls during drying. By
this technique, we can obtain 3-dimensional ZnO structures that conventional photolithography and nano-imprinting lithography
are hard to achieve in few process steps. 相似文献
16.
This paper provides an effective uniform rate of metastability (in the sense of Tao) on the strong convergence of Halpern iterations of nonexpansive mappings in CAT(0) spaces. The extraction of this rate from an ineffective proof due to Saejung is an instance of the general proof mining program which uses tools from mathematical logic to uncover hidden computational content from proofs. This methodology is applied here for the first time to a proof that uses Banach limits and hence makes a substantial reference to the axiom of choice. 相似文献
17.
Yung-Chieh Tsai Yen-Mei Lee Chih-Hsiung Hsu Sy-Ying Leu Hsiao-Yen Chiang Mao-Hsiung Yen Pao-Yun Cheng 《Experimental & molecular medicine》2015,47(8):e180
Leptin is a peptide hormone, which has a central role in the regulation of body weight; it also exerts many potentially atherogenic effects. Ferulic acid ethyl ester (FAEE) has been approved for antioxidant properties. The aim of this study was to investigate whether FAEE can inhibit the atherogenic effects of leptin and the possible molecular mechanism of its action. Both of cell proliferation and migration were measured when the aortic smooth muscle cell (A10 cell) treated with leptin and/or FAEE. Phosphorylated p44/42MAPK, cell cycle-regulatory protein (for example, cyclin D1, p21, p27), β-catenin and matrix metalloproteinase-9 (MMP-9) proteins levels were also measured. Results demonstrated that leptin (10, 100 ng ml−1) significantly increased the proliferation of cells and the phosphorylation of p44/42MAPK in A10 cells. The proliferative effect of leptin was significantly reduced by the pretreatment of U0126 (0.5 μM), a MEK inhibitor, in A10 cells. Meanwhile, leptin significantly increased the protein expression of cyclin D1, p21, β-catenin and decreased the expression of p27 in A10 cells. In addition, leptin (10 ng ml−1) significantly increased the migration of A10 cells and the expression of MMP-9 protein. Above effects of leptin were significantly reduced by the pretreatment of FAEE (1 and 10 μM) in A10 cells. In conclusion, FAEE exerts multiple effects on leptin-induced cell proliferation and migration, including the inhibition of p44/42MAPK phosphorylation, cell cycle-regulatory proteins and MMP-9, thereby suggesting that FAEE may be a possible therapeutic approach to the inhibition of obese vascular disease. 相似文献
18.
This work prepared poly(ethylene glycol‐co‐1,3/1,4‐cyclohexanedimethanol terephthalate) (PETG)/organoclay nanocomposites via a melt intercalation process and investigated the influences of organoclay aspect ratio and organoclay content on the dispersed state, mechanical, thermal, gas barrier, and heat recovery properties of PETG/organoclay nanocomposites. X‐ray diffraction (XRD) and transmission electron microscopic analyses showed that the organoclay dispersed in the polymer matrix with intercalation in the nanometer scale range. Differential scanning calorimetry (DSC) analysis demonstrated that all of the obtained nanocomposites were amorphous, indicating that the addition of organoclay did not affect the amorphous nature of PETG. The gas barrier properties of the nanocomposites improved with organoclay content and the properties were also affected by the organoclay aspect ratio. Water vapor and oxygen transmission rates (OTRs) of PETG/organoclay nanocomposites containing 3 phr Cloisite 15A, and 3 phr modified polymer grade Na‐montmorillonites (MPGN) were the lowest among the samples tested, and were 41.7 and 44.3%, respectively, of those of neat PETG. Similar organoclay content‐ and aspect ratio‐related effects were observed in the mechanical and heat recovery properties of the tested nanocomposites. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
19.
Yu-Pin Wang Hsien-Li Leu Tso-Shen Lin Gene-Hsiang Lee 《Journal of organometallic chemistry》2008,693(15):2615-2623
With copper(I) iodide as catalyst, σ-alkynyls, compounds (η5-C5H5)Cr(NO)2(CC-C6H5) (5), [(η5-C5H4)-COOCH3]Cr(NO)2(CC-C6H5) (10), and [(η5-C5H4)-COOCH3]W(CO)3(CC-C6H5) (13), were prepared from their corresponding metal chloride 1, 6 and 12. Structures of compound 3, 5 and 12 have been solved by X-ray diffraction studies. In the case of 5, there is an internal mirror plane passing through the phenylethynyl ligand and bisecting the Cp ring. The phenyl group is oriented perpendicularly to the Cp with an eclipsed conformation. The twist angle is 0° and 118.4° for -CC-Ph and two NO ligands, respectively. The orientation is rationalized in terms of orbital overlap between ψ3 of Cp, dπ of Cr atom, and π∗ of alkynyl ligand, and complemented by molecular orbital calculation. The opposite correlation was observed on the chemical shift assignments of C(2)-C(5) on Cp ring in compounds 6 and 12, using HetCOR NMR spectroscopy. The electron density distribution in the cyclopentadienyl ring is discussed on the basis of 13C NMR data and compared with the calculations via density functional B3LYP correlation-exchange method. 相似文献
20.
A stereo disparity-based range finding technique was developed for measuring three-dimensional coordinates of object points. It used an image-matching algorithm which functionally consisted of scene reduction, epipolar line selection, and features matching. Experiments implementing this technique were performed on an industrial vision system. An error analysis indicated that image resolution was the major source of measurement inaccuracy. 相似文献