Rumen fluid fermentation for enhancement of hydrolysis and acidification of grass clipping.

Rumen fluid, formed in rumen of ruminants, includes a complex microbial population of bacteria, protozoa, fungi and archaea, and has high ability to degrade lignocellulosic biomass. In this study, rumen fluid was used to ferment grass clipping for enhancing the hydrolysis and acidification of organic matters. Results showed that strict anaerobic condition, higher grass clipping content and smaller particle size of grass clipping were beneficial to the hydrolysis and acidification of organics. The increase of SCOD and total VFA concentration respectively reached 24.9 and 10.2 g/L with a suitable grass clipping content of 5%, a particle size <0.150 mm, and a fermentation time of 48 h. The VFA production was mainly attributed to the degradation of cellulose and hemicellulose with a total solid reduction of 55.7%. Firmicutes and Fibrobacteres were the major contributors to the degradation of cellulose and hemicellulose. The activity of carboxymethyl cellulose enzyme (CMCase), cellobiase and xylanase reached 0.027, 0.176 and 0.180 U/ml, respectively. The rumen fluid microorganisms successfully enhanced the hydrolysis and acidification of grass clipping.

Immobilization of metals in contaminated soils using natural polymer-based stabilizers.

Three low-cost natural polymer materials, namely, lignin (Ln), carboxymethyl cellulose, and sodium alginate, were used for soil amendment to immobilize lead and cadmium in two contaminated soil samples collected from a mining area in Nanjing, China. The remediation effects of the aforementioned natural polymers were evaluated by toxicity characteristic leaching procedure (TCLP) and sequential extractions. The stabilizers could lower the bioavailability of Pb and Cd in the contaminated soils, and the amount of the exchangeable forms of the aforementioned two metals were reduced evidently. TCLP results showed that the leaching concentrations of Pb and Cd were decreased by 5.46%-71.1% and 4.25%-49.6%, respectively, in the treated soils. The contents of the organic forms of the two metals both increased with the increase in stabilizer dose on the basis of the redistribution of metal forms by sequential extractions. These findings were due to the fact that the abundant oxygen-containing groups on the polymeric amendments were effective in chelating and immobilizing Pb and Cd, which have been further confirmed from the metal adsorptions in aqueous solutions. Moreover, Ln achieved the greatest effect among the three polymers under study because of the former's distinct three-dimensional molecular structure, showing the preferential immobilization of Pb over Cd in soils also. Thus, the above-mentioned natural polymers hold great application potentials for reducing metal ion entry into the food chain at a field scale.

[Effect of covalent functionalization on DNA cleavage activity and ROS formation of single-walled carbon nanotubes].

Biotoxicity of selected covalent functionalizaed single-walled carbon nanotubes (SWNTs) was investigated by plasmid DNA cleavage assay. The effect of covalent functionalization on the physical structural and chemical activity of SWNTs was also studied by Vis-NIR spectroscopy, Raman spectroscopy and ROS assay. The DNA cleavage intensity was promoted by covalent functionalization, and the intensity of DNA damage caused by the three types of carbon nanotubes in a descending order was found to be carboxylated SWNTs (SWNT-COOH) > polyethyleneglycol-lated SWNTs (SWNT-PEG) > uncovalent functionalized SWNTs (uSWNTs). SWNTs were efficient intermediate to trigger electron transfer from electron donor to O2 in dark condition which lead to superoxide radical (O2*-) formation. The electron transfer intensity caused by selected SWNTs was also SWNT-COOH > SWNT-PEG > SWNTs. The reason is that defect sites which changed from sp2-hybridized carbon atom on the side wall of carbon nanotubes were more reactive than the perfect ones.

[The study of magnetic resonance sialography in diagnosing parotid diseases].

OBJECTIVE: To study the feasibility of diagnosing parotid disease with magnetic resonance sialography (MRS) and to select the optimal scanning sequence. METHODS: Twenty-three patients with parotid gland disease and 5 normal adults received sialography using magnetic resonance imaging technique and several sequences (including IR-FSE, FSE, SS-IR-FSE, SS-FSE) were used. After first scanning, the patients were scanned respectively 3 and 10 minutes after buccal application of vitamin C. And MR images of duct obtained. The images of parotid duct system were analysed and evaluated according to their displaying effects. Qualitative diagnosis was made based on MRI and those diagnosis were compared with pathological diagnosis after operation. RESULTS: Images of MR sialography clearly displayed the main duct and its branches of parotid gland and the pathological changes of duct, such as narrow, expanded, stoppage. Of the scanning sequences, IR-FSE was superior to others in manifesting the parotid gland duct (P < 0.05). The performance of images after being given vitamin C did not significantly improve the displaying effect. The accurate rate of qualitative diagnosis was 95.6%. CONCLUSIONS: MR sialography can clearly display the parotid ducts and their pathological changes. The accurate rate of qualitative diagnosis of parotid disease was higher than that X-ray sialography.