[Effects of extraction methods on soil water isotope and plant water source segmentation.] / æå–æ–¹æ³•å¯¹åœŸå£¤æ°´åŒä½ç´ å’Œæ¤ç‰©æ°´æºåˆ†å‰²çš„å½±å“.

We used two types of soil with different physicochemical properties (loam and sand), oven-dried them, and then added the known isotopic composition mineral water that was reference water to compose the soil-water mixture with different soil water contents (loam: 0.15, 0.20, 0.30 g·g-1; sand: 0.10 g·g-1). After that, we set up different equilibrium time (loam: 3, 6, 12, 24, 48, 72, 96 h; sand: 96 h) to ensure that the dry soil particles were well mixed with the added water. The soil water was extracted by mechanical centrifugation and cryogenic vacuum extraction after equilibrium, and their isotope composition was analyzed. Results showed that the isotopic values of soil water extracted by mechanical centrifugation method had no significant difference in same water content with different equilibration times, but were more enriched compared with the reference water isotopic value. The maximum enrichment for hydrogen and oxygen isotope was 7.38‰ and 1.24‰, respectively. In contrast, cryogenic vacuum extraction method resulted in more depleted soil water isotopes than reference water, with the maximum depletion for hydrogen and oxygen isotope being 6.27‰ and 1.03‰, respectively. Moreover, the degree of depletion increased with the increases of equilibrium time (less than 24 h) at low water content, and became stable after 24 h. With the increases of soil water content, the isotopic composition of the extracted soil water was less affected by the two extraction methods. The water isotope value of loam that had high clay content, was more sensitive to the extraction method than the sandy soil that had low clay content. The difference of isotopic composition caused by extraction methods did not affect the plant water source segmentation.

[Improvement of River Water Quality by Aeration: WASP Model Study].

Aeration is one of the main technical methods to remediate polluted rivers, and mathematical models are the main ways to predict and assess the environmental pollution. WASP model was used to study the effect of aeration on improving the water quality of a small river over a time span. The preliminary results showed that the simulation values were consistent with practical monitoring data, which could be useful for the management and control of polluted water. Furthermore, simulations under different aeration conditions suggested that aeration technology could significantly lower the levels of chemical oxygen demand (COD) and ammonia-nitrogen (NH4(+)-N) of river water, thus improving the water quality. With the improvement of dissolved oxygen (DO), the water quality could be further improved. However, the increase in the removal rate of pollutants would slow down. Also, there were remarkable differences among various months throughout the whole year, and aeration from May to September had better results. Considering economic costs and environmental benefits, river aeration with a 4 mg x L(1) DO standard in summer was determined as the best condition.

Relationship between single nucleotide polymorphism of interleukin-18 and susceptibility to pulmonary tuberculosis in the Chinese Han population.

Interleukin-18 (IL-18) is a multi-functional cytokine capable of inducing either Th1 or Th2 polarization depending on the immunologic milieu. IL-18 may influence the host response to Mycobacterium tuberculosis (M.tb) infection. To investigate the relationship between single nucleotide polymorphisms of the IL-18 and susceptibility to pulmonary tuberculosis in the Chinese Han population, the IL-18 gene was sequenced to detect polymorphisms and to examine the genotype frequencies in 300 patients and 702 healthy controls. DNA sequencing revealed three IL-18 variants: rs1946518, rs5744247, and rs549908. It also revealed that allele A of rs1946518 confers a 1.47-fold increased risk of developing tuberculosis (TB) (P = 0.0001, OR [95%CI] = 1.47 [1.21-1.78]), and that the C allele of rs5744247 confers a 0.77-fold decreased risk of disease (P = 0.01, R [95%CI] = 0.77 [0.632-0.937]). The genotypes rs1946518, rs5744247 and rs549908 were found to be significantly associated with TB. Estimation of the frequencies of haplotypes revealed a potential risk haplotype AGA (P = 0.01, OR [95%CI] = 1.41 [1.15-1.72]) and a protective haplotype CCA (P = 0.01, OR [95%CI] = 0.70 [0.57-0.85]) for TB. The present findings suggest that polymorphisms in the IL-18 gene may affect susceptibility to TB and increase the risk of developing the disease in the Chinese Han population.

Nontuberculous mycobacteria: susceptibility pattern and prevalence rate in Shanghai from 2005 to 2008.

BACKGROUND: An increasing incidence of disease caused by nontuberculous mycobacteria (NTM) is being reported. The purpose of this study was to determine the isolation rates of NTM from various clinical specimens, and their antimicrobial susceptibility patterns, over a 4-year period in Shanghai. METHODS: All NTM isolated between 2005 and 2008 at Shanghai Pulmonary Hospital, a key laboratory of mycobacteria tuberculosis in Shanghai, China, were identified with conventional biochemical tests and 16S rRNA gene sequencing. Antimicrobial susceptibility for all NTM was determined using the BACTEC MGIT 960 system. RESULTS: A total of 21,221 specimens were cultured, of which 4868 (22.94%) grew acid fast bacilli (AFB), and 248 (5.09%) of the AFB were NTM. The prevalence rate of NTM was determined as 4.26%, 4.70%, 4.96% and 6.38% among mycobacteria culture positive samples in years 2005, 2006, 2007 and 2008 respectively. These data indicated that the prevalence rate has continuously increased. Sixteen different species of NTM were identified, the most commonly encountered NTM in Shanghai were M. chelonae (26.7%), followed by M. fortuitum (15.4%), M. kansasii (14.2%), M. avium-intracellulare complex (13.1%) and M. terrae (6.9%). The rare species identified were M. marinum, M. gastri, M. triviale, M. ulcerans, M. smegmatis, M. phlci, M. gordonae, M. szulgai, M. simiae, M. scrofulaceum and M. xenopi. The five most commonly identified NTM species showed high drug resistance to general anti-tuberculosis drugs, particularly, M. chelonae and M. fortuitum appear to be multi-drug resistance. CONCLUSIONS: The prevalence of NTM in Shanghai showed a tendency to increase over the course of the study. The five most commonly isolated NTM species showed high drug resistance to first line anti-tuberculosis drugs.