Effects of green manure planted in winter and straw returning on soil aggregates and organic matter functional groups in double cropping rice area.

To explore the mechanism of exogenous organic materials enhancing soil organic carbon and soil fertility, based on a long-term experiment located in Hengyang Red Soil Experimental Station, we examined the effects of winter green manure and straw returning patterns (CK, winter fallow; MV, winter Chinese milk vetch; S, early-season rice straw total returning; DS, early-season and late-season rice straw total returning; SMV, winter Chinese milk vetch + early-season rice straw total returning; DSMV, winter Chinese milk vetch + early-season and late-season rice straw total returning) on soil aggregates and organic functional groups. The results showed that the proportion of super aggregates (>2 mm) and macroaggregates (0.25-2 mm) in double cropping rice soil was the highest with a ratio of about 72.1%-81.8%, and the organic carbon content in the two kinds of aggregates was as high as 12.1-20.7 g·kg-1, accounting for 22.7%-59.0% of the total organic carbon. The main organic functional group in paddy soil was polysaccharides, followed by aliphatic carbon and aromatic carbon. The abundance of all those groups was affected by winter Chinese milk vetch growing and straw returning. Compared with other treatments, DSMV significantly increased the proportion of super aggregates (>2 mm) and macroaggregates (0.25-2 mm) and favored the accumulation of inert carbon such as aromatic carbon in the two kinds of aggregates. DSMV could enhance the stability of soil aggregates and organic matter, which had high potential in the real agricultural production.

Acute esophageal obstruction caused by reverse migration of gastric bezoars: A case report.

BACKGROUND: Bezoars can be found anywhere in the gastrointestinal tract. Esophageal bezoars are rare. Esophageal bezoars are classified as either primary or secondary. It is rarely reported that secondary esophageal bezoars caused by reverse migration from the stomach lead to acute esophageal obstruction. Guidelines recommend urgent upper endoscopy (within 24 h) for these impactions without complete esophageal obstruction and emergency endoscopy (within 6 h) for those with complete esophageal obstruction. Gastroscopy is regarded as the mainstay for the diagnosis and treatment of esophageal bezoars. CASE SUMMARY: A 59-year-old man was hospitalized due to nausea, vomiting and diarrhea for 2 d and sudden retrosternal pain and dysphagia for 10 h. He had a history of type 2 diabetes mellitus for 9 years. Computed tomography revealed dilated lower esophagus, thickening of the esophageal wall, a mass-like lesion with a flocculent high-density shadow and gas bubbles in the esophageal lumen. On gastroscopy, immovable brown bezoars were found in the lower esophagus, which led to esophageal obstruction. Endoscopic fragmentation was successful, and there were no complications. The symptoms of retrosternal pain and dysphagia disappeared after treatment. Mucosal superficial ulcers were observed in the lower esophagus. Multiple biopsy specimens from the lower esophagus revealed nonspecific findings. The patient remained asymptomatic, and follow-up gastroscopy 1 wk after endoscopic fragmentation showed no evidence of bezoars in the esophagus or the stomach. CONCLUSION: Acute esophageal obstruction caused by bezoars reversed migration from the stomach is rare. Endoscopic fragmentation is safe, effective and minimally invasive and should be considered as the first-line therapeutic modality.

[Comparison in cadmium accumulation capacities of different leafy vegetables through cadmium-rich substrate cultivation]. / åˆ©ç”¨å¯Œé•‰åŸºè´¨æ ½åŸ¹å¿«é€Ÿæ¯”è¾ƒä¸åŒå¶èœé•‰ç´¯ç§¯èƒ½åŠ›çš„å·®å¼‚.

To acquire a feasible method for a rapid comparison of the cadmium (Cd) accumulation capacities of different leafy vegetables, using substrate cultivation with different contents of Cd and cultivation time, we compared the observed Cd accumulation capacity with these obtained in the field. The results showed that the Cd content and bio-concentration factors (BCFs) value in the aboveground tissue of leafy vegetable varied significantly with Cd content and cultivation time. Multi-factor analysis of variance showed that vegetable variety, cultivation time, Cd content in substrate and their interaction had significant effects on BCFs of Cd in leafy vegetable. Leafy vegetable variety was the dominant factor affecting BCFs of Cd in leafy vegetable and controlled its absolute level. When Cd content in the substrate reached 1.0 mg·kg-1 with a cultivation of 10 days, the correlation coefficient of Cd BCFs between the substrate cultivation and field experiments was the highest, with a R2 value of 0.90. The results of cluster analysis and one-way ANOVA had the highest consistence with the field results. Comparatively, the substrate cultivation with Cd content of 1.0 mg·kg-1 and a cultivation of 10 days showed a good reproducibility and stability in reflecting the difference in Cd accumulation capacities of different leafy vegetable varieties. The Cd-rich substrate cultivation could be used to screen the vegetables with low Cd accumulation and also would promote the field application of the vegetables with low Cd accumulation in the Cd-contaminated area of China.

rhPLD2 inhibits airway inflammation in an asthmatic murine model through induction of stable CD25+ Foxp3+ Tregs.

Our previous studies have shown that recombinant human phospholipase D2 (rhPLD2) plays a modulator role on NF-κB and PKC signaling pathways. It also inhibits IL-5-induced inflammatory response in chronic asthmatic guinea pigs. Additionally, increasing evidence also has revealed that the adoptive transfer of induced regulatory T cells (Tregs) may be a therapeutic solution to airway allergic diseases. To investigate the epigenetic, transcriptomic and phenotypic variability of Treg population in an ovalbumin (OVA)-induced airway inflammation model derived from the induction of rhPLD2, OVA-induced asthmatic murine model is used in this study. The lung inflammation, eosinophil infiltration, the differentiation and proliferation of T helper cells and the amplification of Tregs were examined in this mouse model with and without rhPLD2 induction. Our data showed that rhPLD2 administration in asthmatic mice significantly increases CD4+CD25+ Foxp3+ Treg cell numbers and alleviates lung inflammation. The addition of rhPLD2 in vitro enhanced the demethylation of Treg-specificdemethylated region (TSDR) in iTregs, suggesting that rhPLD2 protein may be involved in improving the quality and quantity of Treg cells that eventually significantly reduces lung inflammation in asthmatic murine model. These results suggest that rhPLD2 could have a clinical impact treating patients with allergic airway inflammation via promoting and stabilizing iTreg differentiation and function.

[Effects of different fertilization regimes on nitrogen and phosphorus balance and eco-economic benefits in red paddy field.] / 不同施肥措施对红壤稻田氮磷平衡及生态经济效益的影响.

The nitrogen (N) and phosphorus (P) balance was studied and the eco-economic benefits of N and P were evaluated for the paddy field in a red soil area, under the fertilization treatments of no fertilization (CK), chemical fertilizer (NPK), organic fertilizer (M), and chemical fertilizers combined with organic fertilizers (NPKM, NPM, NKM), based on the long-term experiment started in 1982, to optimize fertilizer application and reduce N and P losses. The results indicated that the slight N surplus (27.10 kg·hm-2) and P deficit (-6.85 kg·hm-2) were obtained in CK, while the N and P surplus respectively with 110.94-243.98 kg·hm-2 and 19.06-67.49 kg·hm-2 in other treatments were obtained. The treatments NPK and M had no effects on the N and P balance. Under the same fertilization rates, the N surplus in treatment NPKM was lower than that in treatments NPM and NKM by 6.3% and 12.9%, while the P surplus was lower by 3.7% and 13.8%, respectively. The total-N, total-P, alkali-hydrolyzable N, and available P contents in the 0-20 cm soil layer increased under the treatments of NPKM. Comparatively, the available P contents were relatively higher in the 20-40 cm soil layer under the treatments of high P application rates. Furthermore, the NPKM treatment had the highest eco-economic benefit value of 0.762, which indicated the optimized fertilizer application for the paddy fields in the red soil area. The treatment CK had the lowest eco-economic benefit values with 0.560. Based on the observations, the N and P (in P2O5) fertilization respectively at the rates of 157.71 kg·hm-2 and 112.18 kg·hm-2 could well maintain the N and P balance for the paddy field in the red soil area.

[Aging process of arsenite [As(3)]in soils originated from different parent materials.] / 外源As(⠢)在不同母质发育土壤中的老化过程.

An incubation test was conducted to study the bioavailability and fractionations of exogenous arsenite [As(3)] during the aging period in three soils originated from different parent materials, including quaternary red clay, purple sandy shale and granite. The results indicated that the exogenous arsenite As(3) were totally transformed into As(V) after 120 d aging. The available As content in soils derived from the three soils generally decreased sequentially throughout the aging period in the order of purple sandy shale, granite and quaternary red clay. The pseudo-second-order model well fitted the change of available As content with aging time (P＜0.05). Soil pH, organic matter (SOM) content and the concentrations of Fe, Al and Mn oxides were the main factors influencing the red soil arsenic in aging, especially, Mn oxides played a more crucial role than Fe and Al oxides in As aging (P＜0.05). Correlation analysis revealed that the non-specially and specially absorbed As constituted the primary forms of available As.

Folic acid-targeted magnetic Tb-doped CeF3 fluorescent nanoparticles as bimodal probes for cellular fluorescence and magnetic resonance imaging.

Magnetic fluorescent nanoparticles (NPs) have great potential applications for diagnostics, imaging and therapy. We developed a facile polyol method to synthesize multifunctional Fe3O4@CeF3:Tb@CeF3 NPs with small size (<20 nm), high water solubility and good biocompatibility. The NPs were modified by ligand exchange reactions with citric acid (CA) to obtain carboxyl-functionalized NPs (Fe3O4@CeF3:Tb@CeF3-COOH). Folic acid (FA) as an affinity ligand was then covalently conjugated onto NPs to yield Fe3O4@CeF3:Tb@CeF3-FA NPs. They were then applied as multimodal imaging agents for simultaneous in vitro targeted fluorescence imaging and magnetic resonance imaging (MRI) of HeLa cells with overexpressed folate receptors (FR). The results indicated that these NPs had strong luminescence and enhanced T2-weighted MR contrast and would be promising candidates as multimodal probes for both fluorescence and MRI imaging.

Multifunctional magnetic-hollow gold nanospheres for bimodal cancer cell imaging and photothermal therapy.

Multifunctional nanocomposites combining imaging and therapeutic functions have great potential for cancer diagnosis and therapy. In this work, we developed a novel theranostic agent based on hollow gold nanospheres (HGNs) and superparamagnetic iron oxide nanoparticles (SPIO). Taking advantage of the excellent magnetic properties of SPIO and strong near-infrared (NIR) absorption property of HGNs, such nanocomposites were applied to targeted magnetic resonance imaging (MRI) and photoacoustic imaging (PAI) of cancer cells. In vitro results demonstrated they displayed significant contrast enhancement for T2-weighted MRI and strong PAI signal enhancement. Simultaneously, the nanocomposites exhibited a high photothermal effect under the irradiation of the near-infrared laser and can be used as efficient photothermal therapy (PTT) agents for selective killing of cancer cells. All these results indicated that such nanocomposites combined with MRI-PAI and PTT functionality can have great potential for effective cancer diagnosis and therapy.

[Effects of vegetable cultivation years on microbial biodiversity and abundance of nitrogen cycling in greenhouse soils].

The effects of facility vegetable cultivation years (three, nine, fourteen or seventeen years) on biodiversity and abundance of soil microorganisms, such as bacteria, ammonia oxidizing bacteria (AOB) and nirK type denitrifying bacteria, in the greenhouse soils in Wuwei of Gansu Province, China were determined by the combined analyses of terminal restriction fragment length polymorphism (T-RFLP) and real-time quantitative PCR. The results showed that the dominant population structure and abundance of bacteria, AOB, nirK type denitrifying bacteria in the soils were significantly different from those in the farmland fields. The dominant population also changed with the cultivation years. With the increase of vegetable cultivation years, the abundance of 16S rRNA and nirK gene in the 0-20 cm soil layer first increased and then decreased, with the maximum values of 9.67 x 10(9) and 2.30 x 10(7) copies x g(-1) soil at year 14 and year 9, being as 1.51 and 1.52 times of that of the 3-year, respectively. However, the abundance of amoA gene showed an opposite trend. The amoA gene copy number in the 14-year sample was 3.28 x 10(7) copies x g(-1) soil, which was only 45.7% of that of the 3-year. These results illustrated that the ecological adaptation mechanisms of the different functional microorganisms involved in nitrogen cycling had significant differences in the facility vegetable soils, and provided a base for further researches on exploring and explaining the characteristics and adaptation mechanisms of microorganisms in greenhouse soil.

[Effects of different fertilization regimes on abundance and community structure of the nirK-type denitrifying bacteria in greenhouse vegetable soils].

The community structure and abundance of nirK-type denitrifying bacteria in different soil layers (0-20 cm and 20-40 cm) under various fertilization regimes in Wuwei, Gansu Province were investigated by the combination of terminal restriction fragment length polymorphism (T-RFLP) and real-time quantitative PCR. Results showed that the nirK-type denitrifying bacteria community structure was significantly affected by fertilization regimes, especially for 70, 156 and 190 bp T-RFs that represented the dominant populations in greenhouse soil. Fertilization regimes significantly influenced the abundance of nirK gene in the 0-20 cm soil layer with the highest abundance of nirK gene copy number (2.16 x 10(7) copies x g(-1) soil) detected in the manure treatment (M), which was 2.04 and 2.02 times of that in the control (CK) and chemical fertilizer (NPK) treatments, respectively. Both the dominant population and abundance of nirK-type denitrifying bacteria in the greenhouse soil were significantly different between the 0-20 cm and 20-40 cm soil layers, and the nirK-type denitrifying bacteria community structure and abundance in the greenhouse soil were obviously different from that in the field. Soil pH, soil organic matter content and nitrate-N content had the greatest influence on the bacterial community composition. Phylogenetic analysis indicated that there were not only anaerobic nirK-type denitrifying bacteria in greenhouse soil, but also aerobic denitrifying bacteria, such as Rhizobium, Ochrobactrum, Agrobacterium.

Folic acid-conjugated silica-coated gold nanorods and quantum dots for dual-modality CT and fluorescence imaging and photothermal therapy.

Multifunctional nanoparticles (NPs) have great potential for multimodal cancer imaging and effective therapy. We have developed multifunctional NPs (GNR@SiO2@QDs) by incorporating gold nanorods (GNRs) and CdSe/ZnS quantum dots (QDs) into silica. Folic acid (FA) as a targeting ligand was covalently conjugated on the surfaces of GNR@SiO2@QDs with a silane coupling agent. Cell viability assay showed that these NPs had low cytotoxicity. And confocal fluorescence images illustrated that they could selectively target HeLa cells overexpressing folate receptors (FRs) rather than FR-deficient A549 cells. In vitro cell imaging experiments revealed that these NPs exhibited strong X-ray attenuation for X-ray computed tomography (CT) imaging and strong fluorescence for fluorescence imaging. They also showed an enhanced photothermal therapy (PTT) effect for cancer cells due to GNRs' high absorption coefficient in the near infrared (NIR) region and a better heat generation rate. All results show that they have great potential in theranostic applications such as for targeted tumor imaging and therapy.

[Effects of exogenous dimethylarsinic acid on Brassica campestris growth and soil arsenic bioavailability].

A pot experiment was conducted to study the effects of exogenous dimethylarsinic acid (DMA) on the growth of Brassica campestris and the bioavailability of soil arsenic (As). With the increasing concentration of applied DMA, the emergence rate and biomass of B. campestris increased at low concentration DMA, but decreased at high concentration DMA. When the DMA concentration reached 90 mg x kg(-1), the emergence rate and biomass of B. campestris in the second cropping decreased by 9.5% and 57.0%, respectively, compared with those in the control, indicating that exogenous DMA had longer-term effects on the growth of B. campestris. The soil available As and the As uptake by B. campestris all increased with increasing concentration of exogenous DMA, and there existed significant correlations among them. After applied into soil, the exogenous DMA demethylated, with As(V) as the main product and lesser amount of As (III), and the concentrations of soil As(V) and As(III) increased with increasing application rate of exogenous DMA.

[Concentration and speciation of arsenic in greenhouse vegetable soil in Shouguang County of Shandong Province].

A sampling survey was conducted in the typical areas in Shouguang County of Shandong Province to study the characteristics of arsenic (As) concentration and speciation in greenhouse vegetable soil. The total As concentration in the surface (0-20 cm) and subsurface (20-40 cm) soil was averagely 8.27 and 7.93 mg x kg(-1), being 19% and 23% higher than that of the control (open field soil), and the soluble As (AE-As) concentration was 0.13 and 0.06 mg x kg(-1), 63% and 200% higher than that of the control, respectively. The ratio of residual As (O-As) to total arsenic reached more than 63.0%, and the concentrations of different As speciation decreased in the order of O-As > iron-bound As (Fe-As) > calcium bound As (Ca-As) > aluminum bound As (AlAs) > AE-As. With the increasing planting years, the AE-As concentration enhanced significantly, and the Al-As concentration also increased to some degree. After 15 years planting, the AE-As concentration in surface and subsurface soil increased by 75.0% and 150.0%, and Al-As concentration increased by 51.6% and 190.4%, respectively, while the concentrations of Fe-As and Ca-As all decreased to some degree.

[Effects of organic fertilization on arsenic absorption of pakchoi (Brassica chinensis) on arsenic-contaminated red soil].

A pot experiment with arsenic-contaminated red soil was conducted to study the effects of applying pig dung and chicken manure on the growth and arsenic absorption of pakchoi (Brassica chinensis), and on soil available arsenic. Applying pig dung and chicken manure to the arsenic-contaminated red soil increased the biomass of pakchoi to some extent. Comparing with the control, applying pig dung increased the pakchoi biomass significantly (P < 0.05). The soil available arsenic content after applying pig dung increased by 394.9%-1033.6% (P < 0.05), and that after applying chicken manure increased by 30.4%-94.1%. Organic fertilization promoted the arsenic absorption of pakchoi, with the arsenic uptake after applying pig dung increased by 20.7%-53.9%. The application of pig dung and chicken manure to arsenic-contaminated red soil could somewhat increase the soil available arsenic content and the arsenic uptake by crops, and thus, increase the risks of agricultural product quality and environment.

[Soil arsenic content and its health risk assessment for agricultural products in the region surrounding Shimen arsenic sulphide mine].

A systematic investigation was carried out on the arsenic content in the soils and plants surrounding Shimen arsenic sulphide mine. The arsenic content in top soils (0-20 cm) was averagely 99.51 mg x kg(-1), being 5.34 times higher than that of the background value in Hunan Province and 8.70 times higher than that of local farmland soil. The topsoil arsenic content in paddy field and dry land was 43.51 and 115.1 mg x kg(-1), respectively, being 0.45 and 1.87 times higher than that of the grade II level (paddy field 30 mg x kg(-1); dry land 40 mg x kg(-1)) commended by the National Soil Quality (GB 15618-1995), and the corresponding arsenic exceeding rate was 62.5% and 50.0%, respectively. The arsenic content in edible parts of foodstuff, vegetables, and fruits was 0.16, 0.06, and 0.01 mg x kg(-1), respectively, and the arsenic exceeding rate of crop samples compared to food security standard ranked in the order of foodstuff > vegetables > fruits. Rice and sweet potato were relatively seriously contaminated by arsenic. The highest arsenic content of rice was up to 0.84 mg x kg(-1), which was 4.6 times higher than that of the National Standard, with the exceeding rate of 62.5%. Statistical analysis demonstrated that there was a positive correlation between the arsenic contents of soil and plant. The average daily intake of arsenic by local people through the consumption of the crops was 6.416 microg x kg(-1) x d(-1), which was much higher than the standard commended by WHO, and the related health risk index was 21.39, which was 14.39 times higher than that in the control region.

[Effects of exogenous dissolved organic matter and temperature on copper forms in red soil].

A simulating incubation test was conducted to evaluate the effects of exogenous dissolved organic matter (DOM) and incubation temperature on the copper forms in red soil. Comparing with the control, adding different amount of DOM increased the content of soil exchangeable Cu, but decreased the content of soil Fe-Mn bound Cu. With increasing time of incubation, the content of soil exchangeable Cu in all DOM-added treatments had a decreasing trend. By the end of the incubation, treatment 250 mg DOM x L(-1) had the highest contents of soil exchangeable Cu and carbonate bound Cu, while treatment 500 mg DOM x L(-1) had the highest content of soil Fe-Mn bound Cu. In the treatments with DOM addition, the content of soil organic bound Cu increased by 10.67%-23.66%, compared with the control. At incubation temperature 25 degrees C and 45 degrees C, the contents of soil exchangeable Cu and Fe-Mn bound Cu decreased with increasing time of incubation; while at 5 degrees C, an opposite trend was observed. At these three temperatures, the content of soil carbonate bound Cu in treatments with DOM addition increased with incubation time. The content of soil organic bound Cu increased with increasing temperature, but that of soil residual Cu decreased at lower temperature (5 degrees C).

[Influence of flooding on form transformation of soil arsenic].

An incubation test was conducted to study the dynamics of exogenously supplied dimethylarsenic acid (DMA), monomethylarsonic acid (MMA), and As(V) in soil under flooding. With the increasing time of incubation, the exogenously supplied DMA and MMA were mainly transformed into As(V), and the As(V) concentration increased, being significantly higher after incubated for 150 days, compared with that after incubated for 1 day. The exogenously supplied DMA was demethylated into As(V) within 30 days, accompanied by a little As(III), while the transformation rate of exogenously supplied MMA was rather slow within 60 days, accompanied by a little As(III) and DMA. The exogenously supplied As(V) decreased with increasing time of incubation, and its form had less change except that a little As(III) occurred.

[Action mechanisms of microorganisms on arsenic and the feasibility of utilizing fungi remediation of arsenic-contaminated soil].

Utilizing fungi to remediate arsenic-contaminated soil and water body has a great potential, which has been focused and highlighted in environmental sciences. Though the arsenic in environment can not be biodegraded as organic contaminants, its bioavailability can be affected by microorganisms via the processes oxidation/reduction, absorption/desorption, methylation/demethylation, and precipitation/dissolution, etc., and thereby, its toxicity could be reduced, and the arsenic-contaminated environment could be remediated. This paper introduced the action mechanisms of microorganisms on arsenic, summarized the research progress in the arsenic bioaccumulation and bio-volatilization by fungi, and discussed the feasibility of utilizing fungi in the remediation of arsenic-contaminated soil, aimed to provide theoretical reference for the bioremediation strategies of arsenic-contaminated soils.

[Distribution characteristics of heavy metals in soil profile of facility vegetable fields].

Taking the facility vegetable fields having been planted for 1-12 years and the adjacent wheat land in Shouguang City of Shandong Province as test objects, this paper studied the distribution characteristics of arsenic (As), cadmium (Cd), copper (Cu), zinc (Zn), chromium (Cr), and nickel (Ni) in their soil profiles (0-150 cm). With the increase of soil depth, the test heavy metals contents in the soil profiles all had a decreasing trend, and in the same soil layers, the contents were obviously higher in facility vegetable fields than in wheat land. Comparing with those in the same soil layers of wheat land, the average contents of As, Cd, Cu, Zn, Cr, and Ni in 0-20 and 120-150 cm soil layers of facility vegetable fields were 35.0%, 146.2%, 65.6%, 36.4%, and 21.5%, and 10.6%, 178.5%, 19.4%, 20.2%, 15.2%, and 9.3% higher, respectively, and the average contents of the heavy metals in 20-120 cm soil layer of facility vegetable fields were also higher in some degree. In the 0-20 cm soil layer of facility vegetable fields, the Cd, Cu, and Zn contents had significant positive correlations with planting years (P < 0.05), with the accumulation rates of Cd, Cu, and Zn being 0.027, 1.153, and 2.830 mg x kg(-1) x a(-1), respectively. In facility vegetable fields, the test six heavy metals contents were significantly positively correlated with the contents of soil organic carbon and total nitrogen, and the Cd, Cu, Zn, and Cr contents were significantly correlated with the content of soil total phosphorus (P < 0.01). Applying organic fertilizer could induce the heavy metals accumulation in the soils of facility vegetable fields to some extent.

[Heavy metals cycling and its regulation in China cropland ecosystems].

This paper analyzed the current situation of heavy metal contamination in cropland soils in China, and discussed the input, output, and balance of heavy metals in cropland ecosystems. It was considered that heavy metals had definite accumulation in cropland ecosystems, but overall speaking, this accumulation had relatively small environmental risk, and only some plants, especially vegetables, accumulated heavy metals over the standards. In mining areas, adjacent areas of smelting plants, and the farming areas using larger amounts of related wastes, the heavy metals content in plants and soils was at least ten times higher than that in normal croplands, existing larger environmental risk. Aiming at the current situation of heavy metal contamination of farmland soils in China, some effective regulation measures for the heavy metal cycling in the cropland ecosystems were proposed, and the further research prospects in related fields were discussed.