[Objective] This study aimed to screen a bacterial strain capable of producing bioflocculant. [Method] A bacterial strain T-11 capable of producing bioflocculant was isolated from activated sludge. Detailed tests on t...[Objective] This study aimed to screen a bacterial strain capable of producing bioflocculant. [Method] A bacterial strain T-11 capable of producing bioflocculant was isolated from activated sludge. Detailed tests on the morphological, physiological and biochemical characteristics were carried out and identification was performed to identify the strain. Finally, the bioflocculant was isolated and purified, and the flocculating activity and chemical characteristics were measured. [Result] It was identified as Serratia plumuthica based on its morphological, physiological and biochemical characteristics. This strain secreted flocculant best in a culture medium which included sucrose and NaNO3. The maximal cell growth was achieved within 10 h and the flocculating activity paralleled to it. It was found to be effective for flocculation of kaolin suspension, when added at a final concentration of 0.7 mg/L, over a range of pHs （2-7）, and temperature （approximately 30-80 ℃）. Chemical analysis indicated that the bioflocculant was an acidic polysaccharide consisting of glucose, glucuronic acid and galactose, talose and altrose. Infrared spectrum analysis also revealed typical characteristics of polysaccharides. [Conclusion] The biofloccu- lants produced by strain T-11 can greatly improve the ability of activated sludge to settle.展开更多
In order to regenerate electric power from the vibration excited by road unevenness,a novel energy- regenerative active suspension for vehicles was proposed with the description of its structure and its working princi...In order to regenerate electric power from the vibration excited by road unevenness,a novel energy- regenerative active suspension for vehicles was proposed with the description of its structure and its working principle with two modes switched in different operating conditions.Then,the novel active system was modeled and simulated to show the performance improvement in ride comfort in its electrical motor mode.Finally,the performance tests of the actuator prototype were carried out,which proves its capability for damping in its regenerative braking mode.The research results can provide useful guidance for the similar electrical active suspension design and development.展开更多
A K+-selective electrode and a Na+-selective electrode were used to construct a measuring cell without liquid-junction for the determination of the ion activity ratio of K+ to Na+ in soil suspensions. The measured cel...A K+-selective electrode and a Na+-selective electrode were used to construct a measuring cell without liquid-junction for the determination of the ion activity ratio of K+ to Na+ in soil suspensions. The measured cell potential was not affected by the total electrolyte concentration when the total cation concentration was 10-1-10-3 mol L-1 and the concentration ratio CK+ / CNa+. was 10:1 to 1:50. When the concentration ratios were equal to 1and the total electrolyte concentrations were 10-2 and 10-3 mol L-1, the ion activity ratio measurement would not be affected by pH in the pH range of 3.5 to 11.5 and 4.4 to 11 respectively. Ions other than H+ have no remarkable influence on the measurement. The ion activity ratio of K+ to Na+ measured directly in soil suspension agree well with those in centrifuged supernant solution. The relative deviation was within 4%. From the measured ion activity ratio, the difference of the bonding energies of K+ and Na+ ions was calculated.展开更多
Traditionally, coconut dregs will be used as animal feed after the extraction of coconut oil and coconut milk from the copra. This study was carried out to discover the commercial value of coconut dregs as a solid sub...Traditionally, coconut dregs will be used as animal feed after the extraction of coconut oil and coconut milk from the copra. This study was carried out to discover the commercial value of coconut dregs as a solid substrate in the production of amylase through solid state fermentation （SSF） since this agro-waste is fairly rich in nutrients, providing the necessary nutrients supplementation for better microbial activity to produce enzymes. In this study, amylase is to be produced from coconut dregs by Aspergillus niger through solid state fermentation （SSF）. Three parameters were covered, which are incubation time, initial moisture content of substrate and inoculum sizes. SSF was carried out by using incubator at 37 ~C to test for enzyme activity at these following parameters： incubation time： 24, 48, 72, 96 and 120 hours; substrate moisture content： 64, 66, 68, 70 and 72% （w/w）; inoculum sizes： 0.5, 1.0, 1.5, 2.0, 2.5 and 3.0 mL spore suspension （5.5 × 10^6 spores/mL）. Enzyme activities were measured through the estimation of liberated reducing sugars after the assay of amylase enzyme by using DNS （3, 5 dinitrosalicylic acid） method. Highest enzyme activities were obtained at these following parameters： incubation time： 72 hours （31.76 U/gds）; initial moisture content ofsubstrate： 66% （26.66 U / gds） and inoculum sizes： 2.0 mL （30.56 U/gds）.展开更多
Methylene bis(thiocyanate)(MBT) is insoluble in water, so suspension concentrate(SC) of MBT is extremely relied on surfactants. In this paper, SC of MBT was prepared with wet-grinding technology, and the effect of sur...Methylene bis(thiocyanate)(MBT) is insoluble in water, so suspension concentrate(SC) of MBT is extremely relied on surfactants. In this paper, SC of MBT was prepared with wet-grinding technology, and the effect of surfactants,such as Morwet D425(D425) and Morwet EFW(EFW)(two kinds of dispersant), on the Zeta potential and rheology behavior of MBT SC were investigated. The results showed that the Zeta potential absolute value of MBT SC increased with the increasing content of D425, and it decreased with the increasing content of EFW at acidic solution(pH = 4.5). In the combination system of D425 and EFW, Zeta potential of MBT SC decreased first and then increased with the increasing content of EFW. The relationship between shear rate(γ) and viscosity(η) was studied according to Herschel–Bulkley model: η = η0+ k/γ, and the relationship between shear rate(γ) and shear force(τ) was investigated according to:τ = τ0+Kγ~n. It was revealed that the mixed fluid belonged to Yield Pseudoplastic Fluid.展开更多
The effects of bacterial-feeding nematodes on bacterial number, activity, and community composition were studied through a microcosm experiment using sterilized soil inoculated with soil bacteria （soil suspension） a...The effects of bacterial-feeding nematodes on bacterial number, activity, and community composition were studied through a microcosm experiment using sterilized soil inoculated with soil bacteria （soil suspension） and with bacteria and three species of bacterial-feeding nematodes （ Cephalobus persegnis, Protorhabditis filiformis, and Caenorhabditis elegans）. Catalyzed reporter deposition-fluorescence in situ hybridization, CO2 evolution, and denaturing gradient gel electrophoresis （DGGE） of PCR ampli- fied 16S rRNA gene fragments were used to investigate bacterial numbers, antivity, and community composition, respectively. Our results showed that bacterial numbers and activity significantly increased in the presence of bacterial-feeding nematodes, which indicated that bacterial-feeding nematodes had a significant positive effect on soil bacteria. The different nematode species had different effects on bacterial numbers and activity. C. persegnis and P. filiformis, isolated from native soil, increased the bacterial number and activity more than C. elegans. The DGGE analysis results showed that dominant bacterial species significantly differed among the treatments, which suggested that bacterial-feeding nematode species modified the bacterial community composition in soil. Further gene sequence analysis results showed that the dominant bacterial species in this study were gram-negative bacteria. Given the completely same conditions except nematode species, the varied selective feeding behavior of different nematode species was the most likely reason for the altered bacterial community composition. Overall, the alteration of bacterial numbers, activity and community composition resulting from the bacterial-feeding nematodes may ult!mately affect soil ecological functioning and processes.展开更多
基金Supported by the Science Research Project of Qingdao Technical College in 2012(12-A-2)~~
文摘[Objective] This study aimed to screen a bacterial strain capable of producing bioflocculant. [Method] A bacterial strain T-11 capable of producing bioflocculant was isolated from activated sludge. Detailed tests on the morphological, physiological and biochemical characteristics were carried out and identification was performed to identify the strain. Finally, the bioflocculant was isolated and purified, and the flocculating activity and chemical characteristics were measured. [Result] It was identified as Serratia plumuthica based on its morphological, physiological and biochemical characteristics. This strain secreted flocculant best in a culture medium which included sucrose and NaNO3. The maximal cell growth was achieved within 10 h and the flocculating activity paralleled to it. It was found to be effective for flocculation of kaolin suspension, when added at a final concentration of 0.7 mg/L, over a range of pHs （2-7）, and temperature （approximately 30-80 ℃）. Chemical analysis indicated that the bioflocculant was an acidic polysaccharide consisting of glucose, glucuronic acid and galactose, talose and altrose. Infrared spectrum analysis also revealed typical characteristics of polysaccharides. [Conclusion] The biofloccu- lants produced by strain T-11 can greatly improve the ability of activated sludge to settle.
基金The National Natural Science Foundation of China(No.50575141)
文摘In order to regenerate electric power from the vibration excited by road unevenness,a novel energy- regenerative active suspension for vehicles was proposed with the description of its structure and its working principle with two modes switched in different operating conditions.Then,the novel active system was modeled and simulated to show the performance improvement in ride comfort in its electrical motor mode.Finally,the performance tests of the actuator prototype were carried out,which proves its capability for damping in its regenerative braking mode.The research results can provide useful guidance for the similar electrical active suspension design and development.
文摘A K+-selective electrode and a Na+-selective electrode were used to construct a measuring cell without liquid-junction for the determination of the ion activity ratio of K+ to Na+ in soil suspensions. The measured cell potential was not affected by the total electrolyte concentration when the total cation concentration was 10-1-10-3 mol L-1 and the concentration ratio CK+ / CNa+. was 10:1 to 1:50. When the concentration ratios were equal to 1and the total electrolyte concentrations were 10-2 and 10-3 mol L-1, the ion activity ratio measurement would not be affected by pH in the pH range of 3.5 to 11.5 and 4.4 to 11 respectively. Ions other than H+ have no remarkable influence on the measurement. The ion activity ratio of K+ to Na+ measured directly in soil suspension agree well with those in centrifuged supernant solution. The relative deviation was within 4%. From the measured ion activity ratio, the difference of the bonding energies of K+ and Na+ ions was calculated.
文摘Traditionally, coconut dregs will be used as animal feed after the extraction of coconut oil and coconut milk from the copra. This study was carried out to discover the commercial value of coconut dregs as a solid substrate in the production of amylase through solid state fermentation （SSF） since this agro-waste is fairly rich in nutrients, providing the necessary nutrients supplementation for better microbial activity to produce enzymes. In this study, amylase is to be produced from coconut dregs by Aspergillus niger through solid state fermentation （SSF）. Three parameters were covered, which are incubation time, initial moisture content of substrate and inoculum sizes. SSF was carried out by using incubator at 37 ~C to test for enzyme activity at these following parameters： incubation time： 24, 48, 72, 96 and 120 hours; substrate moisture content： 64, 66, 68, 70 and 72% （w/w）; inoculum sizes： 0.5, 1.0, 1.5, 2.0, 2.5 and 3.0 mL spore suspension （5.5 × 10^6 spores/mL）. Enzyme activities were measured through the estimation of liberated reducing sugars after the assay of amylase enzyme by using DNS （3, 5 dinitrosalicylic acid） method. Highest enzyme activities were obtained at these following parameters： incubation time： 72 hours （31.76 U/gds）; initial moisture content ofsubstrate： 66% （26.66 U / gds） and inoculum sizes： 2.0 mL （30.56 U/gds）.
基金Supported by Guangzhou Science Technology and Innovation Commission(201508030019)China Scholarship Council(201506155073)National Undergraduate Innovative and Entrepreneurial Training Program(201610561089)
文摘Methylene bis(thiocyanate)(MBT) is insoluble in water, so suspension concentrate(SC) of MBT is extremely relied on surfactants. In this paper, SC of MBT was prepared with wet-grinding technology, and the effect of surfactants,such as Morwet D425(D425) and Morwet EFW(EFW)(two kinds of dispersant), on the Zeta potential and rheology behavior of MBT SC were investigated. The results showed that the Zeta potential absolute value of MBT SC increased with the increasing content of D425, and it decreased with the increasing content of EFW at acidic solution(pH = 4.5). In the combination system of D425 and EFW, Zeta potential of MBT SC decreased first and then increased with the increasing content of EFW. The relationship between shear rate(γ) and viscosity(η) was studied according to Herschel–Bulkley model: η = η0+ k/γ, and the relationship between shear rate(γ) and shear force(τ) was investigated according to:τ = τ0+Kγ~n. It was revealed that the mixed fluid belonged to Yield Pseudoplastic Fluid.
基金Supported by the National Natural Science Foundation of China(Nos.41271270 and 31200409)
文摘The effects of bacterial-feeding nematodes on bacterial number, activity, and community composition were studied through a microcosm experiment using sterilized soil inoculated with soil bacteria （soil suspension） and with bacteria and three species of bacterial-feeding nematodes （ Cephalobus persegnis, Protorhabditis filiformis, and Caenorhabditis elegans）. Catalyzed reporter deposition-fluorescence in situ hybridization, CO2 evolution, and denaturing gradient gel electrophoresis （DGGE） of PCR ampli- fied 16S rRNA gene fragments were used to investigate bacterial numbers, antivity, and community composition, respectively. Our results showed that bacterial numbers and activity significantly increased in the presence of bacterial-feeding nematodes, which indicated that bacterial-feeding nematodes had a significant positive effect on soil bacteria. The different nematode species had different effects on bacterial numbers and activity. C. persegnis and P. filiformis, isolated from native soil, increased the bacterial number and activity more than C. elegans. The DGGE analysis results showed that dominant bacterial species significantly differed among the treatments, which suggested that bacterial-feeding nematode species modified the bacterial community composition in soil. Further gene sequence analysis results showed that the dominant bacterial species in this study were gram-negative bacteria. Given the completely same conditions except nematode species, the varied selective feeding behavior of different nematode species was the most likely reason for the altered bacterial community composition. Overall, the alteration of bacterial numbers, activity and community composition resulting from the bacterial-feeding nematodes may ult!mately affect soil ecological functioning and processes.
