[Objective] This study aimed to establish molecular identification methods for Bacillus licheniformis. [Method] Based on clone sequencing and difference analysis for 16S and ITS sequences of B. licheniformis TS-01, sp...[Objective] This study aimed to establish molecular identification methods for Bacillus licheniformis. [Method] Based on clone sequencing and difference analysis for 16S and ITS sequences of B. licheniformis TS-01, specific primers were designed using region sequences as the targets used for amplifying all test strains. [Result] The specific primers of B. licheniformis were designed from the ITS and 16S rDNA regions. The optimal annealing temperature of the specific primers for PCR was 67.2 ℃ with 24 cycles. A 905 bp marker fragment was amplified for B. licheniformis TS-01, while all other test strains showed negative results. This indicated that a specific 16S-ITS marker was obtained, which accurately identified the strain at the species level. [Conclusion] This molecular identification method for B. licheniformis TS-01 has laid the foundation for molecular diagnosis of B. licheniformis.展开更多
[ Objective ] The aim of this study was to investigate the epidemic status of porcine pleuropneumonia in western Shandong and establish the PCR method of actinobacillus pleuropneumoniae (APP). [ Method] The epidemic...[ Objective ] The aim of this study was to investigate the epidemic status of porcine pleuropneumonia in western Shandong and establish the PCR method of actinobacillus pleuropneumoniae (APP). [ Method] The epidemic status of APP in lesion tissues of 186 death pigs and 545 health pigs without clinical symptoms was analyzed by PCR method. [ Result] APP positive rate in 186 samples accounted for 43.0% (80/186), while that in 545 porcine serums accounted for 9.4% (51/545). [ Conclusion] This PCR method can be used as one of the important means for APP clinical diagnosis.展开更多
Anchor bolts are commonly used throughout underground mining and tunnelling operations to improve roof stability.However,premature failures of anchor bolts are significant safety risks in underground excavations aroun...Anchor bolts are commonly used throughout underground mining and tunnelling operations to improve roof stability.However,premature failures of anchor bolts are significant safety risks in underground excavations around the world due to susceptible bolt materials,a moist and corrosive environment and tensile stress.In this paper,laboratory experiments and hydrogeochemical models were combined to investigate anchor bolt corrosion and failure associated with aqueous environments in underground coal mines.Experimental data and collated mine water chemistry data were used to simulate bolt corrosion reactions with groundwater and rock materials with the PHREEQC code.A series of models quantified reactions involving iron and carbon under aerobic and anaerobic conditions in comparison with ion,pH and pE trends in experimental data.The models showed that corrosion processes are inhibited by some natural environmental factors,because dissolved oxygen would cause more iron from the bolts to oxidize into solution.These interdisciplinary insights into corrosion failure of underground anchor bolts confirm that environmental factors are important contributors to stress corrosion cracking.展开更多
To research the anchoring effect of large deformation bolt,tensile and drawing models are established.Then,the evolution laws of drawing force,bolt axial force and interfacial shear stress are analyzed.Additionally,th...To research the anchoring effect of large deformation bolt,tensile and drawing models are established.Then,the evolution laws of drawing force,bolt axial force and interfacial shear stress are analyzed.Additionally,the influence of structure element position on the anchoring effect of large deformation bolt is discussed.At last,the energy-absorbing support mechanism is discussed.Results show that during the drawing process of normal bolt,drawing force,bolt axial force and interfacial shear stress all gradually increase as increasing the drawing displacement,but when the large deformation bolt enters the structural deformation stage,these three values will keep stable;when the structure element of large deformation bolt approaches the drawing end,the fluctuation range of drawing force decreases,the distributions of bolt axial force and interfacial shear stress of anchorage section are steady and the increasing rate of interfacial shear stress decreases,which are advantageous for keeping the stress stability of the anchorage body.During the working process of large deformation bolt,the strain of bolt body is small,the working resistance is stable and the distributions of bolt axial force and interfacial shear stress are steady.When a rock burst event occurs,the bolt and bonding interface cannot easily break,which weakens the dynamic disaster degree.展开更多
In this paper, a calculation formula on spherical pattern of tide-isostasy model is established. The calculation indicated that for the oceanic crust plate which central angle is over 90°, a huge value(its equiva...In this paper, a calculation formula on spherical pattern of tide-isostasy model is established. The calculation indicated that for the oceanic crust plate which central angle is over 90°, a huge value(its equivalence is 108 N)of accumulative force moment in the crustal isostatic movement caused by tide can trigger off relative motion of plate, resulting in earthquake and volcanic eruption. The seismic wave features during the year 2001-2004 is an obvious example. The paracycles, i.e. 4, 12, 60, 36, 243, 372 and 396 years of tidal fluctuation can provide an explanation for some respective natural disasters. For example, La Madre paracycle about 60 years corresponds to the global disasters,earthquake and typhoon disasters.展开更多
AIM: To establish the most common vacA alleles in Helicobacter pylori ( H pylon) strains isolated from Chilean patients and its relationship with gastritis and gastroduodenal ulcers, METHODS: Two hundred and forty...AIM: To establish the most common vacA alleles in Helicobacter pylori ( H pylon) strains isolated from Chilean patients and its relationship with gastritis and gastroduodenal ulcers, METHODS: Two hundred and forty five Hpyloriclinical isolates were obtained from 79 biopsies from Chilean infected patients suffedng from gastrointestinal diseases. An average of 2-3 strains per patient was isolated and the vac4 genotype was analyzed by PCR and 3% agarose electrophoresis. Some genotypes were checked by DNA sequencing. RESULTS: The most prevalent vacA genotype in Chilean patients was slb ml (76%), followed by sla ml (21%). In oontrast, the s2 m2 genotype was scarcely represented (3%). The slb ml genotype was found most frequently linked to gastropathies (P〈0.05) rather than ulcers. Ulcers were found more commonly in male and older patients. Curiously, patents IMng in dties located North and far South of Santiago, thecapital and largest Chilean city, carried almost exclusively strains with the slb ml genotype. In contrast, patients from Santiago and cities located South of Santiago carded strains with either one or both sla ml and slb ml genotypes. Regarding the s2 m2 genotype, comparison with GenBank sequences revealed that Chilean s2 sequence was identical to those of Australian, American, and Colombian strains but quite different from those of Alaska and India. CONCLUSION: Differences in geographic distribution of the s and m vacA alleles in Chile and a relationship of slb ml genotype with gastritis were found. Sequence data in part support a hispanic origin for the vacA genotype. Asymmetric distribution of genotypes slb ml and s2 m2 recedes H Pyloristrain distribution in Spain and Portugal.展开更多
In this research the results of studies on optimization of alkaline protease production by Bacillus licheniformis are reported. The parameters, which were taken into consideration, are pH, temperature, time course of ...In this research the results of studies on optimization of alkaline protease production by Bacillus licheniformis are reported. The parameters, which were taken into consideration, are pH, temperature, time course of enzyme production, stirring rate and kinetics parameters. The effect of various carbon and nitrogen sources in culture medium compound on enzyme production was also considered The result of optimization revealed that maximum protease production was obtained at 37 ℃, pH equivalent tol 0.0 and with 150 rpm will occur after 72 hours. By comparing the effect of 5 carbon sources (maltose, glucose, starch, casein and lactose) in enzyme production, it has been known that using lactose will increase about 1.5 times enzyme production, compared to condition in which maltose is used. The result of studies on the effect of five nitrogen sources (i.e., peptone, tryptone, ammonium sulfate, urea and corn steep liquor) shows that corn steep liqour increases enzyme production more than others, while peptone can also be considered as a good nitrogen source; but, ammonium sulfate and urea reduce enzyme production considerably. It was concluded that protease production occurs in the stationary phase of growth. Studying the kinetics parameters resulted that the best model for the enzyme above is Lineweaver-Burk model according to which Km is 0.64 mmol and Vmax is 88 lamol/min.展开更多
Given the difficulties encountered in roadway support under coal pillars,we studied the characteristics of stress distribution and their effect on roadway stability,using theoretical analysis and numerical simulation....Given the difficulties encountered in roadway support under coal pillars,we studied the characteristics of stress distribution and their effect on roadway stability,using theoretical analysis and numerical simulation.The results show that,under a coal pillar,vertical stress in a floor stratum increases while horizontal stress decreases.We conclude that the increased difference between vertical and horizontal stress is an important reason for deformation of the surrounding rock and failures of roadways under coal pillars.Based on this,we propose control technologies of the surrounding rock of a roadway under a coal pillar,such as high strength and high pre-stressed bolt support,cable reinforcement support single hydraulic prop with beam support and reinforcement by grouting of the surrounding rock,which have been successfully applied in a stability control project of a roadway under a coal pillar.展开更多
Al Jabal al Akhdar(Green Mountain) in arid northern Oman has freshwater resources that had supported small communities for hundreds of years. Jabal Akhdar receives more rainfall(300-400 mm) when compared to the desert...Al Jabal al Akhdar(Green Mountain) in arid northern Oman has freshwater resources that had supported small communities for hundreds of years. Jabal Akhdar receives more rainfall(300-400 mm) when compared to the desert plains. In the last few years, this region had undergone enormous changes due to rapid development. The resident and transient populations have increased and their activities exert severe stress on the water resources. There are 24 retention reservoirs in the area, but most are eutrophic and the nutrient loading is due to input of animal fecal matter via surface run-off. As expected, these waters contaminated with coliform bacteria and some have pathogenic Escherichia coli. Drinking water needs of all the villages met by groundwater extraction. Because of poor quality, the surface water in the reservoirs is under-utilized. A low-cost lowmaintenance treatment system designed, constructed and operated in one village to clean the reservoir water for non-drinking human use. The treatment unit improved the water quality parameters. A survey among the adult male population of the village showed their eagerness to adopt this system and use the treated reservoir water for uses other than agriculture. Establishment of these treatment units in other villages should reduce the pressures on groundwater extraction.展开更多
Bifidobacteria play an important role in maintaining human health, and suppress harmful bacteria by controlling the pH of the large intestine. About 14 strains of the Bifidobacteria have been isolated from the faeces ...Bifidobacteria play an important role in maintaining human health, and suppress harmful bacteria by controlling the pH of the large intestine. About 14 strains of the Bifidobacteria have been isolated from the faeces of infants nursed exclusively from the maternal milk (their ages less than 5 months) from commercial French yoghurt (active bifidus] and from milk (celia bifidus) on MRS medium (containing 0.05% cysteine-HC1, with nalidixic acid 2 mg rel). A total of six strain are strict anaerobic and gram-positive Bifidobacteria, identified as, B. longum (60% of the samples) was the most frequently found species, followed by B. bifidum (21.0%), B. breve (19%). These strains were evaluated for potential use as probiotics based on their adhesion to intestinal epithelial cells, resistance towards acidic (resistance to low pH) and bile conditions, pH values ranging from 6.5 to 7, however, these strains are sensitive to the pH 8, Bifidobacterium are mesophiles with optimal growth at 36℃ to 41℃. All isolates studied have a fast growth in glucose.展开更多
Microbial flocculants have become a hot spot in recent years. A bacterial strain with high flocculating activity was isolated from seawater samples. The strain was defined as Bacillus licheniformis dhs-40 by 16S rDNA ...Microbial flocculants have become a hot spot in recent years. A bacterial strain with high flocculating activity was isolated from seawater samples. The strain was defined as Bacillus licheniformis dhs-40 by 16S rDNA identification and Biolog test. Ultrasonication test confirmed the flocculating activity of the strain was both in fermentation supernatant and cell. According to flocculating activity curve, the ideal fermentation time for collecting flocculating active substances was two days. The flocculating activity of the strain was sensitive to pH. The strain could only preserve flocculating activity while pH varied from 7 to 11. However, it could preserve flocculating activity while temperature varied from -20℃to 100 ℃ Saccharide, protein, lipid, nucleic acids qualitative test and RNase, Proteinase K treatment confirmed the flocculating active substances were proteins. Their flocculating activities were insensitive to Proteinase K.展开更多
In order to improve the yield of β-mannase and to investigate the rules of fermentation production, a high-yield β-mannase producing strain, Bacillus licheniformis HDYM-04, was used to investigate the kinetics model...In order to improve the yield of β-mannase and to investigate the rules of fermentation production, a high-yield β-mannase producing strain, Bacillus licheniformis HDYM-04, was used to investigate the kinetics models based on the optimal fermentation conditions: HDYM-04 strain was fermented at 37℃ for 30 h with agitation speed at 300 r/min and aeration rate at 3 L/min in a 5 L fermenter, the initial addition amount of konjac flour was 2%(w/v), the initial pH of medium was 8.0, and the inoculum concentration was 6.7%(v/v). Three batch fermentation kinetic models were established (cell growth kinetic model, substrate consumption kinetic model, product formation kinetic model) bases on Logistic and Luedeking-Piret equations. To be specific, cell growth kinetic model was dX/dt =0.431X (1- X/ 15.522 ), substrate consumption kinetic model was -ds/dt =1.11 dX/dt +0.000 2 dP/dt +0.000 8X, and product formation kinetic model was dP/dt=133.1 dX +222.87X. The correlation coefficients R^2 of the three equations were 0.990 21, 0.989 08 and 0.988 12, respectively, which indicated a good correlation between experimental values and models. Therefore, the three equations could be used to describe the processes of cell growth, enzyme synthesis and substrate consumption during batch fermentation using B. licheniformis strain HDYM-04. The establishment of batch fermentation kinetic models (cell growth kinetic model, substrate depletion kinetic model, product formation kinetic model) could lay the theoretical foundation and provide practical reference for the applica- tion of HDYM-04 in fermentation industry.展开更多
The movement principle of sidewalls and floor of extraction opening is analyzed, it is found that floor heave not only has something to do with the floor strata, but sidewalls. The effect of sidewall anchor and corner...The movement principle of sidewalls and floor of extraction opening is analyzed, it is found that floor heave not only has something to do with the floor strata, but sidewalls. The effect of sidewall anchor and corner anchor is studied, the mechanical principle of reinforcing sidewalls and corners is put forward and applied in engineering practice.展开更多
Gateway floor heave control is the key to guarantee mine safe and efficient production. Through analysis of floor instability characteristics and bolting control, gateway floor strata show second level stress under ab...Gateway floor heave control is the key to guarantee mine safe and efficient production. Through analysis of floor instability characteristics and bolting control, gateway floor strata show second level stress under abutment pressure, which causes plastic flow failure in floor strata; gateway floor instability shows mainly shear-break slippage of "triangle sliding body". Mechanics of floor bolting is mainly a function of connection and combination. Main area of bolting control lies in two gateway floor angles. The paper analyzes mechanics principle of gateway floor instability, constructs stability mechanics model of gateway floor bolting, obtains gateway floor stability criterion of different bolting angles and optimum formula of bolting parameters, carries out the engineering example, and guides better field application. It provides theoretical base for bolting gateway floor instability control.展开更多
In recent years, seasonal blooms of the dinoflagellate Noctiluca miliaris have appeared in the open-waters of the northern Arabian Sea (NAS). This study provides the first characterization of bacteria from a seasona...In recent years, seasonal blooms of the dinoflagellate Noctiluca miliaris have appeared in the open-waters of the northern Arabian Sea (NAS). This study provides the first characterization of bacteria from a seasonal bloom of green Noctiluca ofNAS (20°N-17°N and 64°E-70°E), during the spring-inter-monsoon cruise ofSagar Sampada 253, in March 2007. Bacterial growth as assessed by most-probable number (MPN) and plate counts, revealed 'variable-physiotypes' over a wide range of salinities (0%-25% w/v NaC1), pH levels (5-8.5), and organic nutrient strengths, in comparison to non-bloom waters. MPN indices of bacteria in surface waters of bloom stations *DWK and *PRB, corresponded to (3.08-4.41)×103 cells/mL at 3.5% NaC1 (w/v), and (2.82-9.49)× 102 cells/mL at 25% (w/v) NaC1 in tryptone-yeast extract broth (TYE). Plate counts were (1.12-4) × 106 CFU/mL at 0% (w/v) NaC1, (1.28-3.9) × 106 CFU/mL at 3.5% (w/v) NaC1, and (0.4- 7)×104 CFU/mL at 25% NaC1 (w/v) on TYE. One-tenth-strength Zobell's gave (0.6-3.74)× 105 CFU/mL at pH 5 to (3.58-7.5)× 105 CFU/mL at pH 8.5. These bacteria were identified to the genera Bacillus, Cellulomonas, Staphylococcus, Planococcus, Dietzia, Diergibacillus, Micrococcus, Sporosarcinae, Leucobacter, and Halomonas. The identity of three strains (GUFBSS253N2, GUFBSS253N30, and GUFBSS253N84) was confirmed through 16S rDNA sequence homology as Bacillus cohnii, Bacillusflexus, and Bacillus cereus. The -2-3-fold higher plate counts of culturable bacteria from the open-waters of the NAS indicate that these bacteria could critically determine the biogeochemical dynamics of the bloom and its milieu. The role of these bacteria in sustaining/terminating the bloom is under evaluation.展开更多
Detection of waterborne pathogens in drinking water via rapid DNA amplification assays is an important and crucial public health method. The aim of this study is to investigate the presence of waterborne pathogens in ...Detection of waterborne pathogens in drinking water via rapid DNA amplification assays is an important and crucial public health method. The aim of this study is to investigate the presence of waterborne pathogens in groundwater resources in Al Arroub, Tulkarem and Jericho areas using direct PCR (polymerase chain reaction) analysis. Forty-six groundwater samples were collected. The total DNA was extracted from each sample and subjected to PCR analysis directed to specific genes of enteric bacteria, β-lactamases producing bacteria, L. pneumophila (Legionella pneumophila) and H. pylori (Helicobacter pylori). Enteric bacteria were detected with high frequency in Palestinian water sources followed by 13% occurrence of β-lactamases producing bacteria, 9% of H. pylori and 4% of L. pneumophila. The study shows that shallow groundwater wells and water taped from karstic aquifer is potential for contamination and could not be reliable sources of potable water.展开更多
文摘[Objective] This study aimed to establish molecular identification methods for Bacillus licheniformis. [Method] Based on clone sequencing and difference analysis for 16S and ITS sequences of B. licheniformis TS-01, specific primers were designed using region sequences as the targets used for amplifying all test strains. [Result] The specific primers of B. licheniformis were designed from the ITS and 16S rDNA regions. The optimal annealing temperature of the specific primers for PCR was 67.2 ℃ with 24 cycles. A 905 bp marker fragment was amplified for B. licheniformis TS-01, while all other test strains showed negative results. This indicated that a specific 16S-ITS marker was obtained, which accurately identified the strain at the species level. [Conclusion] This molecular identification method for B. licheniformis TS-01 has laid the foundation for molecular diagnosis of B. licheniformis.
基金Supported by Visiting Scholar Fund for Outstanding Young Teachersin colleges and Universities of Shandong~~
文摘[ Objective ] The aim of this study was to investigate the epidemic status of porcine pleuropneumonia in western Shandong and establish the PCR method of actinobacillus pleuropneumoniae (APP). [ Method] The epidemic status of APP in lesion tissues of 186 death pigs and 545 health pigs without clinical symptoms was analyzed by PCR method. [ Result] APP positive rate in 186 samples accounted for 43.0% (80/186), while that in 545 porcine serums accounted for 9.4% (51/545). [ Conclusion] This PCR method can be used as one of the important means for APP clinical diagnosis.
基金Project(140100153)supported by Australian Research Council Linkage Grant。
文摘Anchor bolts are commonly used throughout underground mining and tunnelling operations to improve roof stability.However,premature failures of anchor bolts are significant safety risks in underground excavations around the world due to susceptible bolt materials,a moist and corrosive environment and tensile stress.In this paper,laboratory experiments and hydrogeochemical models were combined to investigate anchor bolt corrosion and failure associated with aqueous environments in underground coal mines.Experimental data and collated mine water chemistry data were used to simulate bolt corrosion reactions with groundwater and rock materials with the PHREEQC code.A series of models quantified reactions involving iron and carbon under aerobic and anaerobic conditions in comparison with ion,pH and pE trends in experimental data.The models showed that corrosion processes are inhibited by some natural environmental factors,because dissolved oxygen would cause more iron from the bolts to oxidize into solution.These interdisciplinary insights into corrosion failure of underground anchor bolts confirm that environmental factors are important contributors to stress corrosion cracking.
基金Project(2019SDZY02)supported by the Major Scientific and Technological Innovation Project of Shandong Provincial Key Research Development Program,ChinaProject(51904165)supported by the National Natural Science Foundation of ChinaProject(ZR2019QEE026)supported by the Shandong Provincial Natural Science Foundation,China。
文摘To research the anchoring effect of large deformation bolt,tensile and drawing models are established.Then,the evolution laws of drawing force,bolt axial force and interfacial shear stress are analyzed.Additionally,the influence of structure element position on the anchoring effect of large deformation bolt is discussed.At last,the energy-absorbing support mechanism is discussed.Results show that during the drawing process of normal bolt,drawing force,bolt axial force and interfacial shear stress all gradually increase as increasing the drawing displacement,but when the large deformation bolt enters the structural deformation stage,these three values will keep stable;when the structure element of large deformation bolt approaches the drawing end,the fluctuation range of drawing force decreases,the distributions of bolt axial force and interfacial shear stress of anchorage section are steady and the increasing rate of interfacial shear stress decreases,which are advantageous for keeping the stress stability of the anchorage body.During the working process of large deformation bolt,the strain of bolt body is small,the working resistance is stable and the distributions of bolt axial force and interfacial shear stress are steady.When a rock burst event occurs,the bolt and bonding interface cannot easily break,which weakens the dynamic disaster degree.
文摘In this paper, a calculation formula on spherical pattern of tide-isostasy model is established. The calculation indicated that for the oceanic crust plate which central angle is over 90°, a huge value(its equivalence is 108 N)of accumulative force moment in the crustal isostatic movement caused by tide can trigger off relative motion of plate, resulting in earthquake and volcanic eruption. The seismic wave features during the year 2001-2004 is an obvious example. The paracycles, i.e. 4, 12, 60, 36, 243, 372 and 396 years of tidal fluctuation can provide an explanation for some respective natural disasters. For example, La Madre paracycle about 60 years corresponds to the global disasters,earthquake and typhoon disasters.
基金Supported by FONDECYT, Comision Nacional Cientifica y Tecnologica, Chile No.1000730 No.1030894 and No. 1000734 from and NIH No.DK54495
文摘AIM: To establish the most common vacA alleles in Helicobacter pylori ( H pylon) strains isolated from Chilean patients and its relationship with gastritis and gastroduodenal ulcers, METHODS: Two hundred and forty five Hpyloriclinical isolates were obtained from 79 biopsies from Chilean infected patients suffedng from gastrointestinal diseases. An average of 2-3 strains per patient was isolated and the vac4 genotype was analyzed by PCR and 3% agarose electrophoresis. Some genotypes were checked by DNA sequencing. RESULTS: The most prevalent vacA genotype in Chilean patients was slb ml (76%), followed by sla ml (21%). In oontrast, the s2 m2 genotype was scarcely represented (3%). The slb ml genotype was found most frequently linked to gastropathies (P〈0.05) rather than ulcers. Ulcers were found more commonly in male and older patients. Curiously, patents IMng in dties located North and far South of Santiago, thecapital and largest Chilean city, carried almost exclusively strains with the slb ml genotype. In contrast, patients from Santiago and cities located South of Santiago carded strains with either one or both sla ml and slb ml genotypes. Regarding the s2 m2 genotype, comparison with GenBank sequences revealed that Chilean s2 sequence was identical to those of Australian, American, and Colombian strains but quite different from those of Alaska and India. CONCLUSION: Differences in geographic distribution of the s and m vacA alleles in Chile and a relationship of slb ml genotype with gastritis were found. Sequence data in part support a hispanic origin for the vacA genotype. Asymmetric distribution of genotypes slb ml and s2 m2 recedes H Pyloristrain distribution in Spain and Portugal.
文摘In this research the results of studies on optimization of alkaline protease production by Bacillus licheniformis are reported. The parameters, which were taken into consideration, are pH, temperature, time course of enzyme production, stirring rate and kinetics parameters. The effect of various carbon and nitrogen sources in culture medium compound on enzyme production was also considered The result of optimization revealed that maximum protease production was obtained at 37 ℃, pH equivalent tol 0.0 and with 150 rpm will occur after 72 hours. By comparing the effect of 5 carbon sources (maltose, glucose, starch, casein and lactose) in enzyme production, it has been known that using lactose will increase about 1.5 times enzyme production, compared to condition in which maltose is used. The result of studies on the effect of five nitrogen sources (i.e., peptone, tryptone, ammonium sulfate, urea and corn steep liquor) shows that corn steep liqour increases enzyme production more than others, while peptone can also be considered as a good nitrogen source; but, ammonium sulfate and urea reduce enzyme production considerably. It was concluded that protease production occurs in the stationary phase of growth. Studying the kinetics parameters resulted that the best model for the enzyme above is Lineweaver-Burk model according to which Km is 0.64 mmol and Vmax is 88 lamol/min.
基金the National Natural Science Foundation of China(No.50774077)the State Key Laboratory of Coal Resources and Safe Mining Autonomous Study Subject Foundation of China(No.SKLCRSM08X04)+2 种基金the National Basic Research Program of China,the National Excellence Doctor Degree Dissertation Special Foundation of China(No.200760)the New Century Talent Support Program of the Ministry of Education of China(No.NCET-06-0475)the Youth Scientific Research Foundation of China University of Mining & Technology(No. 2008A002)
文摘Given the difficulties encountered in roadway support under coal pillars,we studied the characteristics of stress distribution and their effect on roadway stability,using theoretical analysis and numerical simulation.The results show that,under a coal pillar,vertical stress in a floor stratum increases while horizontal stress decreases.We conclude that the increased difference between vertical and horizontal stress is an important reason for deformation of the surrounding rock and failures of roadways under coal pillars.Based on this,we propose control technologies of the surrounding rock of a roadway under a coal pillar,such as high strength and high pre-stressed bolt support,cable reinforcement support single hydraulic prop with beam support and reinforcement by grouting of the surrounding rock,which have been successfully applied in a stability control project of a roadway under a coal pillar.
文摘Al Jabal al Akhdar(Green Mountain) in arid northern Oman has freshwater resources that had supported small communities for hundreds of years. Jabal Akhdar receives more rainfall(300-400 mm) when compared to the desert plains. In the last few years, this region had undergone enormous changes due to rapid development. The resident and transient populations have increased and their activities exert severe stress on the water resources. There are 24 retention reservoirs in the area, but most are eutrophic and the nutrient loading is due to input of animal fecal matter via surface run-off. As expected, these waters contaminated with coliform bacteria and some have pathogenic Escherichia coli. Drinking water needs of all the villages met by groundwater extraction. Because of poor quality, the surface water in the reservoirs is under-utilized. A low-cost lowmaintenance treatment system designed, constructed and operated in one village to clean the reservoir water for non-drinking human use. The treatment unit improved the water quality parameters. A survey among the adult male population of the village showed their eagerness to adopt this system and use the treated reservoir water for uses other than agriculture. Establishment of these treatment units in other villages should reduce the pressures on groundwater extraction.
文摘Bifidobacteria play an important role in maintaining human health, and suppress harmful bacteria by controlling the pH of the large intestine. About 14 strains of the Bifidobacteria have been isolated from the faeces of infants nursed exclusively from the maternal milk (their ages less than 5 months) from commercial French yoghurt (active bifidus] and from milk (celia bifidus) on MRS medium (containing 0.05% cysteine-HC1, with nalidixic acid 2 mg rel). A total of six strain are strict anaerobic and gram-positive Bifidobacteria, identified as, B. longum (60% of the samples) was the most frequently found species, followed by B. bifidum (21.0%), B. breve (19%). These strains were evaluated for potential use as probiotics based on their adhesion to intestinal epithelial cells, resistance towards acidic (resistance to low pH) and bile conditions, pH values ranging from 6.5 to 7, however, these strains are sensitive to the pH 8, Bifidobacterium are mesophiles with optimal growth at 36℃ to 41℃. All isolates studied have a fast growth in glucose.
文摘Microbial flocculants have become a hot spot in recent years. A bacterial strain with high flocculating activity was isolated from seawater samples. The strain was defined as Bacillus licheniformis dhs-40 by 16S rDNA identification and Biolog test. Ultrasonication test confirmed the flocculating activity of the strain was both in fermentation supernatant and cell. According to flocculating activity curve, the ideal fermentation time for collecting flocculating active substances was two days. The flocculating activity of the strain was sensitive to pH. The strain could only preserve flocculating activity while pH varied from 7 to 11. However, it could preserve flocculating activity while temperature varied from -20℃to 100 ℃ Saccharide, protein, lipid, nucleic acids qualitative test and RNase, Proteinase K treatment confirmed the flocculating active substances were proteins. Their flocculating activities were insensitive to Proteinase K.
基金Supported by Educational Commission of Heilongjiang Province of China(11551z011)
文摘In order to improve the yield of β-mannase and to investigate the rules of fermentation production, a high-yield β-mannase producing strain, Bacillus licheniformis HDYM-04, was used to investigate the kinetics models based on the optimal fermentation conditions: HDYM-04 strain was fermented at 37℃ for 30 h with agitation speed at 300 r/min and aeration rate at 3 L/min in a 5 L fermenter, the initial addition amount of konjac flour was 2%(w/v), the initial pH of medium was 8.0, and the inoculum concentration was 6.7%(v/v). Three batch fermentation kinetic models were established (cell growth kinetic model, substrate consumption kinetic model, product formation kinetic model) bases on Logistic and Luedeking-Piret equations. To be specific, cell growth kinetic model was dX/dt =0.431X (1- X/ 15.522 ), substrate consumption kinetic model was -ds/dt =1.11 dX/dt +0.000 2 dP/dt +0.000 8X, and product formation kinetic model was dP/dt=133.1 dX +222.87X. The correlation coefficients R^2 of the three equations were 0.990 21, 0.989 08 and 0.988 12, respectively, which indicated a good correlation between experimental values and models. Therefore, the three equations could be used to describe the processes of cell growth, enzyme synthesis and substrate consumption during batch fermentation using B. licheniformis strain HDYM-04. The establishment of batch fermentation kinetic models (cell growth kinetic model, substrate depletion kinetic model, product formation kinetic model) could lay the theoretical foundation and provide practical reference for the applica- tion of HDYM-04 in fermentation industry.
文摘The movement principle of sidewalls and floor of extraction opening is analyzed, it is found that floor heave not only has something to do with the floor strata, but sidewalls. The effect of sidewall anchor and corner anchor is studied, the mechanical principle of reinforcing sidewalls and corners is put forward and applied in engineering practice.
基金Supported by the National Natural Science Foundation of China (50874037)
文摘Gateway floor heave control is the key to guarantee mine safe and efficient production. Through analysis of floor instability characteristics and bolting control, gateway floor strata show second level stress under abutment pressure, which causes plastic flow failure in floor strata; gateway floor instability shows mainly shear-break slippage of "triangle sliding body". Mechanics of floor bolting is mainly a function of connection and combination. Main area of bolting control lies in two gateway floor angles. The paper analyzes mechanics principle of gateway floor instability, constructs stability mechanics model of gateway floor bolting, obtains gateway floor stability criterion of different bolting angles and optimum formula of bolting parameters, carries out the engineering example, and guides better field application. It provides theoretical base for bolting gateway floor instability control.
文摘In recent years, seasonal blooms of the dinoflagellate Noctiluca miliaris have appeared in the open-waters of the northern Arabian Sea (NAS). This study provides the first characterization of bacteria from a seasonal bloom of green Noctiluca ofNAS (20°N-17°N and 64°E-70°E), during the spring-inter-monsoon cruise ofSagar Sampada 253, in March 2007. Bacterial growth as assessed by most-probable number (MPN) and plate counts, revealed 'variable-physiotypes' over a wide range of salinities (0%-25% w/v NaC1), pH levels (5-8.5), and organic nutrient strengths, in comparison to non-bloom waters. MPN indices of bacteria in surface waters of bloom stations *DWK and *PRB, corresponded to (3.08-4.41)×103 cells/mL at 3.5% NaC1 (w/v), and (2.82-9.49)× 102 cells/mL at 25% (w/v) NaC1 in tryptone-yeast extract broth (TYE). Plate counts were (1.12-4) × 106 CFU/mL at 0% (w/v) NaC1, (1.28-3.9) × 106 CFU/mL at 3.5% (w/v) NaC1, and (0.4- 7)×104 CFU/mL at 25% NaC1 (w/v) on TYE. One-tenth-strength Zobell's gave (0.6-3.74)× 105 CFU/mL at pH 5 to (3.58-7.5)× 105 CFU/mL at pH 8.5. These bacteria were identified to the genera Bacillus, Cellulomonas, Staphylococcus, Planococcus, Dietzia, Diergibacillus, Micrococcus, Sporosarcinae, Leucobacter, and Halomonas. The identity of three strains (GUFBSS253N2, GUFBSS253N30, and GUFBSS253N84) was confirmed through 16S rDNA sequence homology as Bacillus cohnii, Bacillusflexus, and Bacillus cereus. The -2-3-fold higher plate counts of culturable bacteria from the open-waters of the NAS indicate that these bacteria could critically determine the biogeochemical dynamics of the bloom and its milieu. The role of these bacteria in sustaining/terminating the bloom is under evaluation.
文摘Detection of waterborne pathogens in drinking water via rapid DNA amplification assays is an important and crucial public health method. The aim of this study is to investigate the presence of waterborne pathogens in groundwater resources in Al Arroub, Tulkarem and Jericho areas using direct PCR (polymerase chain reaction) analysis. Forty-six groundwater samples were collected. The total DNA was extracted from each sample and subjected to PCR analysis directed to specific genes of enteric bacteria, β-lactamases producing bacteria, L. pneumophila (Legionella pneumophila) and H. pylori (Helicobacter pylori). Enteric bacteria were detected with high frequency in Palestinian water sources followed by 13% occurrence of β-lactamases producing bacteria, 9% of H. pylori and 4% of L. pneumophila. The study shows that shallow groundwater wells and water taped from karstic aquifer is potential for contamination and could not be reliable sources of potable water.