Perspective texture synthesis has great significance in many fields like video editing, scene capturing etc., due to its ability to read and control global feature information. In this paper, we present a novel example-based, specifically energy optimization-based algorithm, to synthesize perspective textures. Energy optimization technique is a pixel-based approach, so it’s time-consuming. We improve it from two aspects with the purpose of achieving faster synthesis and high quality. Firstly, we change this pixel-based technique by replacing the pixel computation with a little patch. Secondly, we present a novel technique to accelerate searching nearest neighborhoods in energy optimization. Using k- means clustering technique to build a search tree to accelerate the search. Hence, we make use of principal component analysis (PCA) technique to reduce dimensions of input vectors. The high quality results prove that our approach is feasible. Besides, our proposed algorithm needs shorter time relative to other similar methods. 相似文献
Cellulases are the key enzymes used in the biofuel industry. A typical cellulase contains a catalytic domain connected to a carbohydrate-binding module (CBM) through a flexible linker. Here we report the structure of an atypical trimodular cellulase which harbors a catalytic domain, a CBM46 domain and a rigid CBM_X domain between them. The catalytic domain shows the features of GH5 family, while the CBM46 domain has a sandwich-like structure. The catalytic domain and the CBM46 domain form an extended substrate binding cleft, within which several tryptophan residues are well exposed. Mutagenesis assays indicate that these residues are essential for the enzymatic activities. Gel affinity electrophoresis shows that these tryptophan residues are involved in the polysaccharide substrate binding. Also, electrostatic potential analysis indicates that almost the entire solvent accessible surface of CelB is negatively charged, which is consistent with the halophilic nature of this enzyme. 相似文献
Some P-450 systems, notably aromatase and 14-demethylase catalyse not only the hydroxylate reaction but also the oxidation of an alcohol into a carbonyl compound as well as a C---C bond cleavage process. All these reactions occur at the same active site. A somewhat analogous situation is noted with 17-hydroxylase-17,20-lyase that participates in hydroxylation as well as C---C bond cleavage process. The C---C bond cleavage reactions catalysed by the above enzymes conform to the general equation:
It is argued that all three types of reaction catalyzed by these enzymes may be viewed as variations on a common theme. In P-450 dependent hydroxylation the initially formed FeIII---O---O. species is converted into FeIII---O---OH and the heterolysis of the oxygen—oxygen bond of the latter then gives the oxo-derivative for which a number of canonical structures are possible; for example FeV = O ↔ (+.)FeIV = O ↔ FeIV---O.. One of these, FeIV---O. behaves like an alkoxyl radical and participates in hydrogen abstraction from C---H bond to produce FeIV---OH and carbon radical. The latter is then quenched by the delivery of hydroxyl radical from FeIV---OH. The latter species may thus be regarded as a carrier of hydroxyl radical. We have proposed that the C---C bond cleavage reaction occurs through the participation of the FeIII---O---OH species that is trapped by the electrophilic property of the carbonyl compound giving a peroxide adduct that fragments to produce an acyl—carbon cleavage. Scientific developments leading up to this conclusion are considered. In the first author's views,
“The study of mechanisms is not a scientific but a cultural activity. Mechanisms do not aim at an absolute truth but are intended to be a “running” commentary on the status of knowledge in a field. As the structural knowledge in a field advances Mechanisms evolve to take note of the new findings. Just as a constructive “running” commentary provides the stimulus for higher standards of performance, so Mechanisms call for better and firmer structural information from their practitioners”. 相似文献
The present research was conducted in district Jhang, Pakistan, to evaluate the concentration of metals/metalloids in soil and pumpkin (Cucurbita maxima) irrigated with domestic wastewater. Data revealed that the levels of metals and metalloids in soil samples from two different sites were below the safe limits except Cd, whereas, in the vegetable, the concentrations of As, Se, Ni, Mo, Pb, Mn, and Cu were above the safe limits. The levels of 12 metals and metalloids in the soil were ranged between 0.14 to 22.76 mg/kg at site-I and 0.16 to 22.13 mg/kg at site-II. The levels of these metals in the vegetable were found 0.35 to 61.13 mg/kg at site-I and 0.31 to 53.63 mg/kg at site-II. The transfer factor at both sites was highest for As and Co. The pollution load index recorded for Se, Cu, Cd, Mo, Pb, and Co was greater than 1. The daily intake of As, Mn, and Mo was above the oral reference dose, which reflects that the intake of pumpkin is not safe for the inhabitants of the selected sites. The control measures should be taken to phytoextract heavy metals and metalloids from polluted sites so as to reduce the health risks. 相似文献
Phenol, p-cresol, and volatile fatty acids (VFA; acetic, propionic, isobutyric, butyric, isovaleric, and valeric acids) were used as odor indicators of swine waste. Aeration of the waste allowed the indigenous microorganisms to grow and degrade these malodorous substances. The time required for degradation of these substances varied according to the waste used, and it was not necessarily related to their concentrations. Using a minimal medium which contained one of the malodorous compounds as sole carbon source, we have selected from swine waste microorganisms that can grow in the medium. The majority of these microorganisms were able to degrade the same substrate when inoculated in sterilized swine waste but with an efficiency varying from one strain to the other. None of these strains was able to degrade all malodorous substances studied. Within 6 days of incubation these selected strains degraded the following: Acinetobacter calcoaceticus, phenol and all VFA; Alcaligenes faecalis, p-cresol and all VFA; Corynebacterium glutamicum and Micrococcus sp., phenol, p-cresol, and acetic and propionic acids; Arthrobacter flavescens, all VFA. On a laboratory scale, the massive inoculation of swine waste with C. glutamicum or Micrococcus sp. accelerated degradation of the malodorous substances. However, this effect was not observed with all of the various swine wastes tested. These results suggest that an efficient deodorization process of various swine wastes could be developed at the farm level based on the aerobic indigenous microflora of each waste. 相似文献
The performance of The Subhuman Primate Pregnancy Test Kit was evaluated for routine detection of early (days 19-21) pregnancy in the rhesus monkey. Out of 123 confirmed matings, 19 resulted in pregnancy. In the pregnant animals the kit had an accuracy of 73.7%. In the nonpregnant females the accuracy was higher, 88.5%. False positives were encountered in ovariectomized females as well as adult intact males. 相似文献
1. Evidence is presented that cyclic AMP inhibits the incorporation of l-[4,5-(3)H]leucine into protein in a cell-free system from rat liver. This inhibition occurs after aminoacyl-tRNA formation. 2. Microsomal fractions, isolated after the incubation of postmitochondrial supernatant with cyclic AMP and ATP, show a diminished ability to synthesize protein. Both cyclic AMP and ATP are required for this effect. 3. A possible physiological role for the anti-anabolic action of cyclic AMP is discussed in terms of the control of gluconeogenesis. 相似文献
The rotational motions of human fibrinogen in solution at 20 degrees C have been examined, in the 0.2-12-microseconds time range, by measuring the laser-induced dichroism of the triplet state of an erythrosin probe covalently bonded to the protein. The decay of the anisotropy was multiexponential, and up to three correlation times (phi 1 = 380 +/- 50 ns, phi 2 = 1.1 +/- 0.1 microseconds, and phi 3 = 3.3 +/- 0.6 microseconds) were needed to obtain a satisfactory analysis. The experimental data are consistent with the brownian motions of an elongated, rigid particle. If the correlation times are combined with previous data on the intrinsic viscosity of fibrinogen, the rotational and translational diffusive properties of the protein can be reproduced with high accuracy by idealizing it as an elongated ellipsoid of revolution with dimensions (2a x 2b) of (54 +/- 6) x (7.2 +/- 0.5) nm, having rotational diffusion constants of D parallel = (6.2 +/- 0.7) x 10(5) s-1 and D perpendicular = (5 +/- 1) x 10(4) s-1. The possibility of Ca(2+)-dependent changes in the rigidity or conformation of fibrinogen was excluded by examining the submicrosecond time-resolved fluorescence depolarization of 1-methylpyrene conjugates of the protein in the presence of different calcium concentrations. Although there are inherent difficulties to extrapolate the data on isolated fibrinogen molecules to the polymerizing species, this relatively stiff conformation meets the requirements of the classical half-staggered double-stranded model of fibrin polymerization rather better than those of the recently proposed interlocked single-stranded mechanism. 相似文献