Amine-grafted MSU-3 mesoporous silica samples were synthesized from pure and waste silica sources and their CO2 adsorption performances were evaluated. The obtained samples were characterized using X-ray diffraction (XRD), thermogravimetric analysis (TGA), N2 adsorption–desorption isotherm analysis, Fourier transform infrared (FTIR), and transmission electron microscopy (TEM). CO2 adsorption capacities of the samples at different temperatures were determined by TGA. The amine-modified MSU-3 synthesized from waste exhibited the highest CO2 adsorption capacity of 1.32 mmol/g at 25 °C and 1 bar, depending essentially on the porous texture and the amine content of the material. The CO2 adsorption isotherms of the synthesized samples were measured by a static volumetric method. Adsorption isotherm indicated that the amine-modified samples presented significantly higher CO2 adsorption capacity than the pure samples. The Avrami kinetic model fitted the experimental data well and suggested that complex reaction mechanism or the appearance of multiple reaction pathway occurred in the CO2 adsorption.
Agroforestry trees are now well known to play a central role in the build up of nutrients pools and their transformations similar to that of forest ecosystem, however, information on the potential of homegarden trees accumulating and releasing nitrogen (mineralization) is lacking. The present study reports seasonal variations in pool sizes of mineral N (NH4+-N and NO3−-N), and net N-mineralization rate in relation to rainfall and temperature under coconut (Cocos nucifera L.), clove (Eugenia caryophyllata Thunb) and nutmeg (Myristica fragrans Houtt. Nees) trees in a coconut-spice trees plantation for two annual cycles in the equatorial humid climate of South Andaman Island of India. Concentration of NH4+-N was the highest during wet season (May–October) and the lowest during post-wet season (November–January) under all the tree species. On the contrary, concentration of NO3−-N was the lowest in the wet season and the highest during the post-wet season. However, concentrations of the mineral N were the highest under the nutmeg and the lowest under the coconut trees. Like the pool sizes, mean annual mineralization was the highest under the nutmeg (561 mg kg−1 yr−1) and the lowest under the coconut trees (393 mg kg−1 yr−1). Rate of mineralization was the highest during the post-wet season and the lowest during the dry season (February–April) under all the tree species. High rainfall during the wet season, however, reduced the rate of nitrification under all the tree species. The mean annual mineralization was logarithmically related with rainfall amount and mean monthly temperature. 相似文献
Biodegradability of chlorhexidine (CH), triclosan (TC), and benzalkonium chloride (CBA) has been tested in 18 surface water sampling points in the urban area of Buenos Aires. Sampling points were located in both the Reconquista and the Matanza-Riachuelo basins as well as in the La Plata River. High tolerance to the three disinfectants was found and indigenous strains capable of degrading CBA and TC were isolated. Neither tolerance nor biodegradation were correlated with sewage pollution. A strain that degrades CBA was identified as belonging to the genus Pseudomonas using the API20NE system and 16SRNA sequencing. In batch assays, the strain was capable of degrading 100, 200, and up to 500 mg L?1 of CBA in 10, 25, and 46 h respectively with specific growth rates (μ) of 0.56, 0.30, and 0.14 h?1. The efficiency of the process was between 99.5–98.0% in terms of compound removal and between 93.8–89.1% in terms of chemical oxygen demand (COD). The detoxification of the compound as a result of the biodegradation was assessed using Pseudokirchneriella subcapitata, Vibrio fischeri, and Lactuca sativa as test organisms. 相似文献
Fat type in diet is responsible for specific changes in gut microbiota (GM). Extra virgin olive oil (EVOO) has been shown to be beneficial for blood pressure and to produce effects on GM. To analyze the cause-effect relationship between intestinal microbial changes and blood pressure, we studied the effect of EVOO on fecal microbiota and systolic blood pressure (SBP) levels in spontaneously hypertensive rats (SHR). SHR were fed either an enriched EVOO diet or a standard diet for a period of 12 weeks. At the end of the experimental period, the microbial profiles in the feces were studied in both groups by using PCR-denaturing gradient gel electrophoresis. Real-time PCR was used to quantify the selected bacterial groups. The results demonstrated significant differences when using Lactobacillus (p<0.05), clostridia XIV (p<0.01) and universal (p<0.05) primers. A significant (r=?0.475; p=0.04) inverse correlation between the abundance of clostridia XIV and SBP, which depends on the type of diet, was also observed. Finally, the results suggested an increase in the microbial diversity of the feces of the animals fed the EVOO diet. These results strongly connect the pattern of GM in SHR fed a diet enriched with EVOO to the lower levels of SBP observed in these animals at the end of the feeding period. 相似文献
Developing routine methods that accurately predict soil nitrogen (N) mineralization is essential for fertilization recommendation; thus, chemical soil testing has received worldwide attention. However, the optimal chemical soil test for predicting soil N mineralization is region specific. This study aimed to determine suitable chemical soil tests for predicting N mineralization in paddy soils of the Dongting Lake region, China.
Materials and methods
Composite surface samples (0–20 cm) of soils (n?=?30) with diverse inherent properties were collected from representative paddy fields across the region. The benchmark indices for soil N mineralization were the net mineralization rate of soil N in a 112-day anaerobic incubation under waterlogged conditions (NMRN112) and N mineralization potential (No) estimated using a modified double exponential model. Laboratory-based measurements of soil labile organic N (SLON) were conducted using chemical fractionation methods including 0.01 M NaHCO3 extraction, hot 2 M KCl hydrolysis, phosphate-borate (PB) buffer hydrolysis, acidic KMnO4 oxidation, and alkaline KMnO4 oxidation. These were compared with the benchmark indices to assess their suitability for use as indicators for N mineralization.
Results and discussion
Acidic KMnO4-oxidative organic N (acidic KMnO4-N) and PB buffer-hydrolysable organic N (PBHYDR-N) correlated strongly with NMRN112 and No (r?=?0.825–0.884, P?<?0.001, n?=?30). Grouping of soils based on soil texture generally provided no improvement in the relationships of chemical soil tests with NMRN112 and No. Multiple stepwise regression analysis indicated that combining acidic KMnO4-N and PBHYDR-N yielded the best prediction of soil N mineralization, explaining 86.1 and 85.5 % of the variation in NMRN112 and No, respectively, of the 30 tested paddy soils.
Conclusions
The results of acidic KMnO4-N and PBHYDR-N as indicators for soil N mineralization were promising, and the operations of acidic KMnO4 oxidation and PB buffer hydrolysis procedures are simple and cost-effective. Therefore, a combination of acidic KMnO4-N and PBHYDR-N shows promise in predicting N mineralization in paddy soils of the Dongting Lake region. However, further calibration through field studies is required and the chemical characteristics of acidic KMnO4-N and PBHYDR-N needs to be further clarified.
The aim of our study was to characterise the heterogeneity of sediment distribution in a stormwater retention/infiltration
basin (Pont de Cheviré, Nantes, France) and to determine the impact of this distribution on water transfer properties in the
soil. 相似文献
A 3-year-old sexually intact male Bull Mastiff underwent splenectomy for splenic thrombosis; prior to and after splenectomy, multiple blood transfusions were administered. Two weeks after the procedure, T-cell lymphoproliferative disease was diagnosed. Treatment with prednisone and chlorambucil was initiated, and 2 weeks later, cytologic examination of a blood smear revealed small (0.3 microm), coccoid basophilic bodies on the surface of approximately 70% of the RBCs. Morphologically, these resembled "Candidatus Mycoplasma haemominutum." A polymerase chain reaction assay was used to amplify a partial 16S rRNA sequence in blood obtained from the dog; the product was sequenced and compared with 16S rRNA gene sequences of other hemotropic mycoplasmas. The sequence was 98% homologous to that of "Candidatus M haemominutum", but only 77% homologous to that of M haemocanis and M haemofelis. 相似文献
Sulfamethazine (SMT) is increasingly detected in environmental matrices due to its versatile use as antibiotics. We aimed to investigate the benefits and roles of steam activation of biochars with respect to SMT sorption kinetics and equilibrium sorption.
Materials and methods
Biochars were produced from burcucumber plant and tea waste using a pyrolyzer at a temperature of 700 °C for 2 h. The biochar samples were treated with 5 mL min?1 of steam for an additional 45 min for post-synthesis steam activation. The SMT sorption on the unmodified and steam activated biochars were compared.
Results and discussion
The time taken to reach equilibrium was significantly less for steam activated biochars (～4 h) than non-activated biochars (>24 h). Up to 98 % of SMT could be removed from aqueous solutions by steam activated biochars. The sorption kinetic behaviors were well described by the pseudo-second model and SMT sorption rates of steam activated biochars (k2?～?1.11–1.57 mg g?1 min?1) were significantly higher than that of the unmodified biochars (k2?～?0.04–0.11 mg g?1 min?1) because of increased availability of accessible porous structure with averagely larger pore diameters. Moreover, the equilibrium sorption on the unmodified biochars was significantly influenced by increasing solution pH (～30–50 % reduction) because of speciation change of SMT, whereas steam activated biochars manifested much stronger sorption resilience against pH variation (～2–4 % reduction only) because the enhanced porosity offset the effect of unfavorable electrostatic repulsion.
Conclusions
The observed features of steam activated biochars would render their applications more versatile and reliable in field throughout changeable environmental conditions.
Light availability in forest understory is essential for many processes; it is, therefore, a valuable information regarding
forest management. However, its estimation is often difficult and direct measurements are tedious. Models can be used to compute
understory light, but they often require a lot of field data to accurately predict light distribution, particularly in the
case of heterogeneous canopies. 相似文献
