111 research outputs found

    Climate change impact on China food security in 2050

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    Climate change is now affecting global agriculture and food production worldwide. Nonetheless the direct link between climate change and food security at the national scale is poorly understood. Here we simulated the effect of climate change on food security in China using the CERES crop models and the IPCC SRES A2 and B2 scenarios including CO2 fertilization effect. Models took into account population size, urbanization rate, cropland area, cropping intensity and technology development. Our results predict that food crop yield will increase +3-11 % under A2 scenario and +4 % under B2 scenario during 2030-2050, despite disparities among individual crops. As a consequence China will be able to achieve a production of 572 and 615 MT in 2030, then 635 and 646 MT in 2050 under A2 and B2 scenarios, respectively. In 2030 the food security index (FSI) will drop from +24 % in 2009 to -4.5 % and +10.2 % under A2 and B2 scenarios, respectively. In 2050, however, the FSI is predicted to increase to +7.1 % and +20.0 % under A2 and B2 scenarios, respectively, but this increase will be achieved only with the projected decrease of Chinese population. We conclude that 1) the proposed food security index is a simple yet powerful tool for food security analysis; (2) yield growth rate is a much better indicator of food security than yield per se; and (3) climate change only has a moderate positive effect on food security as compared to other factors such as cropland area, population growth, socio-economic pathway and technology development. Relevant policy options and research topics are suggested accordingly

    Hemodialysis catheter-related infection caused by Pannonibacter phragmitetus: a rare case report in China

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    Pannonibacter phragmitetus (P. phragmitetus) is rarely related with human disease. We reported a case of catheter-related infection caused by P. phragmitetus in a 68-year-old woman on hemodialysis. The patient developed recurrent fever during hemodialysis and blood cultures were positive for P. phragmitetus. The patient’s body temperature returned to normal after intravenous cefoperazone/sulbactam treatment, and the hemodialysis catheter was locked with gentamicin and urokinase. The potential anti-infective treatment against P. phragmitetus was discussed

    Effects of a dietary supplement on inflammatory marker expression in middle-aged and elderly hypertensive patients

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    OBJECTIVES: We aimed to explore the effects of diet on the inflammatory response in middle-aged and elderly people with hypertension. METHODS: Thirty overweight or obese patients with stage one hypertension (age range, 45-75 years) were allocated to either the intervention or control group (n=15 per group; age- and sex-matched). Patients in the intervention group consumed a food powder supplement (100 g) instead of a regular meal. The control group maintained their normal dietary habits. This study lasted for six weeks. Blood pressure, inflammatory marker levels, and energy intake were measured before and after the study. RESULTS: After 6 weeks, the diet composition of the intervention group changed significantly (po0.05). The intake of proteins, dietary fibre, monounsaturated fat, and polyunsaturated fat increased significantly (po0.05), while the total energy intake trended towards an increase (p40.05). In the control group, the total energy intake decreased significantly (po0.05). The levels of nuclear factor-kB (NF-kB), soluble intercellular adhesion molecule-1 (sICAM-1) and high sensitivity C-reactive protein (hs-CRP) decreased, and adiponectin increased significantly in the intervention group (po0.05); however, no significant changes were observed in the inflammatory marker levels of the control group. In the intervention group, systolic blood pressure decreased significantly (po0.05), and diastolic blood pressure also exhibited a decreasing trend. No significant change in blood pressure was observed in the control group. CONCLUSION: The consumption of a food powder supplement can improve diet composition, decrease blood pressure and reduce inflammation in middle-aged and elderly overweight or obese hypertensive patients. The food powder supplement may also have an anti-atherosclerotic effect in hypertensive patients

    Anti-Apoptosis Effect of Astragaloside Iv on Alzheimer's Disease Rat Model via Enhancing the Expression of Bcl-2 And Bcl-Xl

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    The aim is to explore the protective effect of Astragaloside IV on Alzheimer’s disease (AD) in rats induced  by amyloid-ß peptide (Aß1-42) and its potential therapeutic mechanism. Methods: 50 Male Sprague Dawley  rats were divided into five groups (10 rats for each): control group, model group, treatment groups 1~3.  10μg Aß1-42 was injected bilaterally into the dorsal dentate gyrus of the hippocampus of rats in the model  and treatment groups to prepare the AD models. 24h after modeling, Astragaloside IV administration, with  different drug dosages of 20mg/(kg•day), 40mg/(kg•day) and 60mg/(kg•day), was performed by gastric  perfusion for rats in the treatment group 1~3. Later on, the cognitive ability of rats was examined by a series  of behavioral tests, and the expression of Bcl-2 and Bcl-xl in the hippocampus of rats was detected by the  fluorescein based Quantitative RT-PCR. Results: The spontaneous alternation test in a Y maze and Morris  water maze task have demonstrated that the repeated daily administration of Astragaloside IV at the doses  of 20mg/kg bw/day) (p<0.05), 40mg/kg bw/day) (p<0.01), and 60mg/kg bw/day) (p<0.01) significantly  ameliorated the impairment of performance caused by Aß1–42. Furthermore, Astragaloside IV also enhanced  the expression of Bcl-2 and Bcl-xl in hippocampal neurons of rats in a dosage-dependent manner. Conclusion:  These findings suggest that Astragaloside IV could alleviate cognitive impairment and enhance the  expression of Bcl-2 and Bcl-xl in hippocampus of rat models with AD.

    Fluctuation of primary motor cortex excitability during cataplexy in narcolepsy

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    Objective Cataplexy is a complicated and dynamic process in narcolepsy type 1 (NT1) patients. This study aimed to clarify the distinct stages during a cataplectic attack and identify the changes of the primary motor cortex (PMC) excitability during these stages. Methods Thirty-five patients with NT1 and 29 healthy controls were recruited to this study. Cataplectic stages were distinguished from a cataplectic attack by video-polysomnogram monitoring. Transcranial magnetic stimulation motor-evoked potential (TMS-MEP) was performed to measure the excitability of PMC during quiet wakefulness, laughter without cataplexy, and each cataplectic stage. Results Based on the video and electromyogram observations, a typical cataplectic attack (CA) process is divided into four stages: triggering (CA1), resisting (CA2), atonic (CA3), and recovering stages (CA4). Compared with healthy controls, NT1 patients showed significantly decreased intracortical facilitation during quiet wakefulness. During the laughter stage, both patients and controls showed increased MEP amplitude compared with quiet wakefulness. The MEP amplitude significantly increased even higher in CA1 and 2, and then dramatically decreased in CA3 accompanied with prolonged MEP latency compared with the laughter stage and quiet wakefulness. The MEP amplitude and latency gradually recovered during CA4. Interpretation This study identifies four stages during cataplectic attack and reveals the existence of a resisting stage that might change the process of cataplexy. The fluctuation of MEP amplitude and MEP latency shows a potential participation of PMC and motor control pathway during cataplexy, and the increased MEP amplitude during CA1 and 2 strongly implies a compensatory mechanism in motor control that may resist or avoid cataplectic attack

    Recombinant Human Endostatin Endostar Inhibits Tumor Growth and Metastasis in a Mouse Xenograft Model of Colon Cancer

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    To investigate the effects of recombinant human endostatin Endostar on metastasis and angiogenesis and lymphangiogenesis of colorectal cancer cells in a mouse xenograft model. Colon cancer cells SW620 were injected subcutaneously into the left hind flank of nude mice to establish mouse xenograft models. The mice were treated with normal saline or Endostar subcutaneously every other day. The growth and lymph node metastasis of tumor cells, angiogenesis and lymphangiogenesis in tumor tissue were detected. Apoptosis and cell cycle distribution were studied by flow cytometry. The expression of VEGF-A, -C, or -D in SW620 cells was determined by immunoblotting assays. Endostar inhibited tumor growth and the rate of lymph node metastasis (P < 0.01). The density of blood vessels in or around the tumor area was 12.27 ± 1.21 and 22.25 ± 2.69 per field in Endostar-treated mice and controls (P < 0.05), respectively. Endostar also decreased the density of lymphatic vessels in tumor tissues (7.84 ± 0.81 vs. 13.83 ± 1.08, P < 0.05). Endostar suppresses angiogenesis and lymphangiogenesis in the lymph nodes with metastases, simultaneously. The expression of VEGF-A, -C and -D in SW620 cells treated with Endostar was substantially lower than that of controls. Endostar inhibited growth and lymph node metastasis of colon cancer cells by inhibiting angiogenesis and lymphangiogenesis in a mouse xenograft model of colon cancer

    Effective Post-Tensioned Splicing System for Prestressed Concrete Piles

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    Precast prestressed concrete piles are widely used in deep foundation construction. Due to unexpected site soil conditions and difficulties associated with transportation and handling long precast piles, splicing is sometimes necessary at the construction site. Available splicing methods utilize steel type connections that are more suitable for reinforced concrete construction and result in limited tensile capacity at the splice. This dissertation describes studies associated with the development of a new post-tensioned splicing system using staggered, embedded anchorages. The new system has the potential to provide the same tensile capacity as a one piece prestressed pile. To develop the post-tensioned splicing system it was necessary to conduct varied numerical analyses to solve immediate technical problems associated with the design, fabrication and testing of a prototype. This included the design of a self-stressing prestressing bed, optimization of the shape of the embedded anchorages and their layout within the piles being spliced. The focus of the dissertation is on non-linear finite element studies conducted to model the flexure behavior of prototype laboratory and full-sized spliced piles in comparison to their identical non-spliced counterpart. Though finite element analysis of prestressed elements is not new, issues relating to modeling post-tensioned, spliced elements with embedded, staggered anchorages have not been the subject of any previous investigation and constitute the principal contribution of this study. Nonlinear finite element analysis was conducted using ANSYS. The William-Warnke failure criterion used to establish concrete failure. A three-dimensional analysis was conducted in which SOLID65 element was used for modeling concrete and LINK8 for the prestressing strands. The post-tensioning ducts were modeled using PIPE20 elements. Perfect bond was assumed between the concrete and the ducts. Embedded anchorages were modeled as fixed locations within the concrete. Epoxy used to join the two splicing surfaces was modeled using contact elements. Since the layout of the post-tensioning ducts was staggered, a full model was required. In contrast, advantage was taken of symmetry for the analysis of the one piece controls. The finite element model was able to accurately capture the flexural behavior of both the control and the spliced piles. The results suggested that tensile separation at the splice interface acted as a pivot about which the section rotated. As a result, the compression failure zone in the spliced pile was confined to a smaller region compared to the control. The stress distribution in the spliced pile indicated that the concrete in the cover above the splice was crushed at the ultimate stage before the steel had yielded. As a result, the ultimate capacity of the spliced pile was controlled by concrete failure. The results also indicated that, among the multiple layers of post-tensioning strands, only one approached yield while others remained in the elastic range. As a result, when the applied load was released, the spliced pile rebounded back to a large degree, which resulted in a much smaller residual permanent deformation. This behavior of a spliced pile can be beneficial for structures in a seismic zone because it will induce smaller secondary moments. This study helped to refine and improve the new post-tensioned splicing system. Its availability makes it possible to extend and further improve the concept without the need for costly prototype fabrication and testing

    Effective Post-Tensioned Splicing System for Prestressed Concrete Piles

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    Precast prestressed concrete piles are widely used in deep foundation construction. Due to unexpected site soil conditions and difficulties associated with transportation and handling long precast piles, splicing is sometimes necessary at the construction site. Available splicing methods utilize steel type connections that are more suitable for reinforced concrete construction and result in limited tensile capacity at the splice. This dissertation describes studies associated with the development of a new post-tensioned splicing system using staggered, embedded anchorages. The new system has the potential to provide the same tensile capacity as a one piece prestressed pile. To develop the post-tensioned splicing system it was necessary to conduct varied numerical analyses to solve immediate technical problems associated with the design, fabrication and testing of a prototype. This included the design of a self-stressing prestressing bed, optimization of the shape of the embedded anchorages and their layout within the piles being spliced. The focus of the dissertation is on non-linear finite element studies conducted to model the flexure behavior of prototype laboratory and full-sized spliced piles in comparison to their identical non-spliced counterpart. Though finite element analysis of prestressed elements is not new, issues relating to modeling post-tensioned, spliced elements with embedded, staggered anchorages have not been the subject of any previous investigation and constitute the principal contribution of this study. Nonlinear finite element analysis was conducted using ANSYS. The William-Warnke failure criterion used to establish concrete failure. A three-dimensional analysis was conducted in which SOLID65 element was used for modeling concrete and LINK8 for the prestressing strands. The post-tensioning ducts were modeled using PIPE20 elements. Perfect bond was assumed between the concrete and the ducts. Embedded anchorages were modeled as fixed locations within the concrete. Epoxy used to join the two splicing surfaces was modeled using contact elements. Since the layout of the post-tensioning ducts was staggered, a full model was required. In contrast, advantage was taken of symmetry for the analysis of the one piece controls. The finite element model was able to accurately capture the flexural behavior of both the control and the spliced piles. The results suggested that tensile separation at the splice interface acted as a pivot about which the section rotated. As a result, the compression failure zone in the spliced pile was confined to a smaller region compared to the control. The stress distribution in the spliced pile indicated that the concrete in the cover above the splice was crushed at the ultimate stage before the steel had yielded. As a result, the ultimate capacity of the spliced pile was controlled by concrete failure. The results also indicated that, among the multiple layers of post-tensioning strands, only one approached yield while others remained in the elastic range. As a result, when the applied load was released, the spliced pile rebounded back to a large degree, which resulted in a much smaller residual permanent deformation. This behavior of a spliced pile can be beneficial for structures in a seismic zone because it will induce smaller secondary moments. This study helped to refine and improve the new post-tensioned splicing system. Its availability makes it possible to extend and further improve the concept without the need for costly prototype fabrication and testing
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