A strain was obtained by screening with which butanol can be fermented by using cellulose hydrolysate. The microorganism not only could use glucose of cellulose hydrolysate,but also could use xylose of cellulose hydrolysate. The growth characteristics,carbon source,nitrogen source and CaCO3 addition in batch fermentation were studied. High concentration glucose and xylose could not be consumed. The optimal concentration of xylose was 20 g/L in batch fermentation. So the initial concentration of xylose in cellulose hydrolysate was 20 g/L with 15 L fermentation reactor,and then cultured for 84 hours at 37 ℃. The yield of butanol was 10.95 g/L,yield of total solvent 16.78 g/L(acetone,ethanol,and butanol),utilization rate of xylose was 70% and total solvent conversion was39.4%. The economic loss by failure of utilization of xylose in cellulose hydrolysate fermentation was resolved.
Recently, high utility itemsets mining becomes one of the most important research issues in data mining due to its ability to consider different profit values for every item. In the past studies, most algorithms generate high utility itemsets from a set of transactions in horizontal data format. Inspired by the problem of frequent itemset mining, vertical mining may be a promising approach superior to horizontal mining. In this paper, a high utility itemsets mining algorithm based on vertical database layout is proposed. Candidate high utility itemsets are discovered by intersection of covers at first. Then, high utility itemsets are checked within candidates by scanning database once. Thus, the advantages of vertical database layout, such as low storage, and high efficiency, are utilized. Experimental results show that the proposed algorithm is both efficient and scalable.
Abstract With the increase of the voltage level of the power system, the demand for electric energy of high energy-consuming enterprises continues to increase, which puts forward higher requirements on the power quality. As power quality problems become more and more prominent, how to manage power quality scientifically and reasonably has attracted more and more attention from power quality workers. At the same time, users have increased their power quality requirements and the continuous development of power marketization. To achieve comprehensive power quality management, it is necessary to have a scientific, accurate, and standardized assessment of power quality. In-depth understanding and understanding of power quality, attach great importance to the harm and impact of power quality degradation on the operation of the power supply system, and it is particularly urgent to achieve comprehensive power quality management.
Xylan is the major component of hemicelluloses, which are the second most abundant polysaccharides in nature, accounting for approximately one-third of all renewable organic carbon resources on earth. Efficient degradation of xylan is the prerequisite for biofuel production. Enzymatic degradation has been demonstrated to be more attractive due to low energy consumption and environmental friendliness, when compared with chemical degradation. Exo-xylanases, as a rate-limiting factor, play an important role in the xylose production. It is of great value to identify novel exo-xylanases for efficient bioconversion of xylan in biorefinery industry. A novel glycoside hydrolase (GH) family 8 reducing-end xylose-releasing exo-oligoxylanase (Rex)-encoding gene (PbRex8) was cloned from Paenibacillus barengoltzii and heterogeneously expressed in Escherichia coli. The deduced amino acid sequence of PbRex8 shared the highest identity of 74% with a Rex from Bacillus halodurans. The recombinant enzyme (PbRex8) was purified and biochemically characterized. The optimal pH and temperature of PbRex8 were 5.5 and 55 °C, respectively. PbRex8 showed prominent activity on xylooligosaccharides (XOSs), and trace activity on xylan. It also exhibited β-1,3-1,4-glucanase and xylobiase activities. The enzyme efficiently converted corncob xylan to xylose coupled with a GH family 10 endo-xylanase, with a xylose yield of 83%. The crystal structure of PbRex8 was resolved at 1.88 Å. Structural comparison suggests that Arg67 can hydrogen-bond to xylose moieties in the -1 subsite, and Asn122 and Arg253 are close to xylose moieties in the -3 subsite, the hypotheses of which were further verified by mutation analysis. In addition, Trp205, Trp132, Tyr372, Tyr277 and Tyr369 in the grove of PbRex8 were found to involve in glucooligosaccharides interactions. This is the first report on a GH family 8 Rex from P. barengoltzii. A novel reducing-end xylose-releasing exo-oligoxylanase suitable for xylose production from corncobs was identified, biochemically characterized and structurally elucidated. The properties of PbRex8 may make it an excellent candidate in biorefinery industries.
Shannon entropy can express unstability of models.This paper introduces the accept of expected entropy and establishes the flowing model about qualified scientists and technicians.It also introduces its selection and tests it with the aid of sampling inspection.
We previously presented the cloning, heterologous expression, and characterization of a novel multidomain endoxylanase from Arthrobacter sp. GN16 isolated from the feces of Grus nigricollis. Molecular and biochemical characterization studies indicate that the glycoside hydrolase (GH) family 10 domain at the N-terminus of the multidomain xylanase (rXynAGN16L) is a low-temperature-active endoxylanase. Many low-temperature-active enzymes contain regions of high local flexibility related to their kinetic and thermodynamic properties compared with mesophilic and thermophilic enzymes. However, the thermodynamic property of low-temperature-active xylanases, including rXynAGN16L, has rarely been reported. In this study, the kinetic and thermodynamic properties of rXynAGN16L were determined using different substrates and temperature conditions to completely characterize its activity properties. The kinetic property of rXynAGN16L is similar to some low-temperature-active GH 10 endoxylanases. Moreover, the thermodynamic property indicates that rXynAGN16L is typically characterized as a low-temperature-active enzyme.
The idle start-stop system is a widely adopted energy-saving system on the passenger car. This study compared the three legal conditions of NEDC, WLTC and CLTC-P, and analyzed the difference in their characteristics as running cycles. Furthermore, the fuel consumption performance of the idle start-stop system is examined under these three legal cycles using fuel consumption simulation software and real vehicle verification. The test results demonstrate that the characteristics of CLTC-P closely resemble actual road driving conditions in China. The fuel-saving effect of the idle start-stop system under CLTC-P is significantly better than that of WLTC and NEDC. Therefore. it is recommended to evaluate other energy-saving devices under CLTC-P.
Abstract Due to the environmental benefits of hybrid electric vehicles, the vehicle population would steadily grow in the next several decades. This paper analyses a large number of road data of buses. The Daily Vehicle Kilometers Travelled of new energy vehicles is 139km and that of internal combustion engine vehicles is 143km. With 50% coverage, both NEVs and ICEVs are 135km. With 80% coverage, both NEVs and ICEVs are 185km. Hybrid electric buses are charged at least once a day. The average charging frequency is 2 times a day in summary. Then construct the utility factor of bus for calculating the comprehensive energy consumption. To verify the validity, a group of experiments were carried out and a new calculation formula was conducted. The comprehensive results by using UF(B) can help users to understand actual energy consumption more clearly.
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