Decomposition experiments of 14C-labelled sickle alfalfa in chao soils of different texture and these soils after removal of CaCO3 were carried out under field and laboratory conditions respectively. The amount of res...Decomposition experiments of 14C-labelled sickle alfalfa in chao soils of different texture and these soils after removal of CaCO3 were carried out under field and laboratory conditions respectively. The amount of residual 14C in, or 14CO2 evolved from, the soils at intervals after the beginning of decomposition were measured and the distribution of native and labelled C between particle size fractions isolated from these soils was edtermined. Results showed that contents of both labelled (14C) and non-labelled (12C) carbon decreased with increasing particle size. The enrichment factor for 14C was higher than that for 12C in the clay fraction, the reverse being true for the silt enrichment factors. The effect of soil texture on the decomposition of plant material could not be observed in chao soils when the clay content was lower than 270g kg-1, while it became obvious once CaCO3 was removed from these soils. The decomposition rate of plant material in the soil from which the native CaCO3 was removed was correlated significantly to both the clay content of the soil and the application rate of CaCO3. A preliminary correction equation describing the effect of clay and CaCO3 on the decomposition of organic material in chao soil was derived from the results obtained.展开更多
In the present study,nano-sized TiO2 /Al2O3 modified PVDF membranes (MM) were fabricated and utilized for anionic polyacrylamide ( APAM) separation. The results showed that,compared with PVDF membrane (OM) ,the contac...In the present study,nano-sized TiO2 /Al2O3 modified PVDF membranes (MM) were fabricated and utilized for anionic polyacrylamide ( APAM) separation. The results showed that,compared with PVDF membrane (OM) ,the contact angle of MM decreases from 83. 64° to 67. 42°,which indicates the increase of the hydrophilicity of MM. The relative flux (RF) decline curve of this ultrafiltration of APAM in water with time shows an obvious two stage properties. The cake filtration models were used to predict the performance of different time over the complete range of filtration times. All the four cake models could simulate this UF process to a certain extent,and the suitability of the two kinds of membranes was: cake filtration > intermediate pore blocking > standard pore blocking > complete pore blocking models. However,they became more and more unsuited to this process with time extending. Surface and cross-sectional morphology of membrane was investigated by SEM to make an advanced certificate of this UF mechanism.展开更多
Nano CaCO3 was used as a condensation agent in the ring-opening reaction of p-tert-butylcalix[4]arene with epichlorohydrin to afford 5,11,17,23-tetra-tert-butyl-26,27,28-trihyd- roxy-25-(1-chloro-2-hydroxy-3-propyl)ca...Nano CaCO3 was used as a condensation agent in the ring-opening reaction of p-tert-butylcalix[4]arene with epichlorohydrin to afford 5,11,17,23-tetra-tert-butyl-26,27,28-trihyd- roxy-25-(1-chloro-2-hydroxy-3-propyl)calix[4]arene regioselectively in 52% yield. The yield was less than 2% by using normal CaCO3 instead of nano one under the same conditions.展开更多
The effects of HDPE matrix toughness on the brittle-ductile transition of HDPE/CaCO_3blends are investigated. Not all HDPE can be toughened by CaCO_3 particles. The ability of thematrix to yield plays a fundamental ro...The effects of HDPE matrix toughness on the brittle-ductile transition of HDPE/CaCO_3blends are investigated. Not all HDPE can be toughened by CaCO_3 particles. The ability of thematrix to yield plays a fundamental role in determing whether HDPE can be toughened or not.There exists a critical matrix toughness (I_(sc)≈45J/m) below which HDPE can not be toughenedobservably by CaCO_3 particle at given average size, and above which the critical matrix ligamentthickness (τ_?) is proportional to matrix impact strength.展开更多
A membrane bioreactor(MBR)with ordinary aeration(reactor R1)and a MBR with microporous aeration(reactor R2)are conducted in parallel to investigate the characteristics of oily sludge and its effect on membrane fouling...A membrane bioreactor(MBR)with ordinary aeration(reactor R1)and a MBR with microporous aeration(reactor R2)are conducted in parallel to investigate the characteristics of oily sludge and its effect on membrane fouling.The results indicate that the order of membrane fouling rate from high to low is:reactor R1 dissolved oxygen(DO)(1 mg/L)>reactor R2 DO(1 mg/L)>reactor R1 DO(4 mg/L)>reactor R2 DO(4 mg/L).Membrane fouling rate is not related to oily sludge concentration but to oily sludge sedimentation performance and the small particle oily sludge is the key factor to affect the membrane fouling.The soluble microbial products(SMP)are examined by three-dimensional excitation-emission matrix(3DEEM)fluorescence spectra.3DEEM spectra demonstrate that the main organic substances of the SMP in two reactors are tyrosine aromatic protein,fulvic acid-like substances and soluble microbial products under DO are1 mg/L and 4 mg/L,respectively.The proportion sum of fulvic acid-like substances and soluble microbial products is the key factor affecting membrane fouling,and membrane fouling accelerates as the ratio increases.展开更多
文摘Decomposition experiments of 14C-labelled sickle alfalfa in chao soils of different texture and these soils after removal of CaCO3 were carried out under field and laboratory conditions respectively. The amount of residual 14C in, or 14CO2 evolved from, the soils at intervals after the beginning of decomposition were measured and the distribution of native and labelled C between particle size fractions isolated from these soils was edtermined. Results showed that contents of both labelled (14C) and non-labelled (12C) carbon decreased with increasing particle size. The enrichment factor for 14C was higher than that for 12C in the clay fraction, the reverse being true for the silt enrichment factors. The effect of soil texture on the decomposition of plant material could not be observed in chao soils when the clay content was lower than 270g kg-1, while it became obvious once CaCO3 was removed from these soils. The decomposition rate of plant material in the soil from which the native CaCO3 was removed was correlated significantly to both the clay content of the soil and the application rate of CaCO3. A preliminary correction equation describing the effect of clay and CaCO3 on the decomposition of organic material in chao soil was derived from the results obtained.
基金Sponsored by the National Natural Science Foundation of China (Grant No.50978068)International Cooperation Program (Grant No.2010DFA92460)+1 种基金National High Technology Research and Development Program of China (863 Program,Grant No.2008AA06Z304)Tianjin Key Laboratory of Aquatic Science and Technology
文摘In the present study,nano-sized TiO2 /Al2O3 modified PVDF membranes (MM) were fabricated and utilized for anionic polyacrylamide ( APAM) separation. The results showed that,compared with PVDF membrane (OM) ,the contact angle of MM decreases from 83. 64° to 67. 42°,which indicates the increase of the hydrophilicity of MM. The relative flux (RF) decline curve of this ultrafiltration of APAM in water with time shows an obvious two stage properties. The cake filtration models were used to predict the performance of different time over the complete range of filtration times. All the four cake models could simulate this UF process to a certain extent,and the suitability of the two kinds of membranes was: cake filtration > intermediate pore blocking > standard pore blocking > complete pore blocking models. However,they became more and more unsuited to this process with time extending. Surface and cross-sectional morphology of membrane was investigated by SEM to make an advanced certificate of this UF mechanism.
基金he Natural Science Foundation of Hubei Province (No. 2000J026) for the financial support.
文摘Nano CaCO3 was used as a condensation agent in the ring-opening reaction of p-tert-butylcalix[4]arene with epichlorohydrin to afford 5,11,17,23-tetra-tert-butyl-26,27,28-trihyd- roxy-25-(1-chloro-2-hydroxy-3-propyl)calix[4]arene regioselectively in 52% yield. The yield was less than 2% by using normal CaCO3 instead of nano one under the same conditions.
基金This project is supported by the National Natural Science Foundation of China.
文摘The effects of HDPE matrix toughness on the brittle-ductile transition of HDPE/CaCO_3blends are investigated. Not all HDPE can be toughened by CaCO_3 particles. The ability of thematrix to yield plays a fundamental role in determing whether HDPE can be toughened or not.There exists a critical matrix toughness (I_(sc)≈45J/m) below which HDPE can not be toughenedobservably by CaCO_3 particle at given average size, and above which the critical matrix ligamentthickness (τ_?) is proportional to matrix impact strength.
基金National Natural Science Foundation of China(No.21173026)Key Program of the Natural Science Foundation of Hubei Province(No.2013CFA107).
文摘A membrane bioreactor(MBR)with ordinary aeration(reactor R1)and a MBR with microporous aeration(reactor R2)are conducted in parallel to investigate the characteristics of oily sludge and its effect on membrane fouling.The results indicate that the order of membrane fouling rate from high to low is:reactor R1 dissolved oxygen(DO)(1 mg/L)>reactor R2 DO(1 mg/L)>reactor R1 DO(4 mg/L)>reactor R2 DO(4 mg/L).Membrane fouling rate is not related to oily sludge concentration but to oily sludge sedimentation performance and the small particle oily sludge is the key factor to affect the membrane fouling.The soluble microbial products(SMP)are examined by three-dimensional excitation-emission matrix(3DEEM)fluorescence spectra.3DEEM spectra demonstrate that the main organic substances of the SMP in two reactors are tyrosine aromatic protein,fulvic acid-like substances and soluble microbial products under DO are1 mg/L and 4 mg/L,respectively.The proportion sum of fulvic acid-like substances and soluble microbial products is the key factor affecting membrane fouling,and membrane fouling accelerates as the ratio increases.
