As one of the extreme climatic events, the frequency and intensity of drought have great impacts on regional water resource. Water is a main limiting factor for plant growth in arid and semi-arid ...regions. Therefore, it is of great scientific significance to explore the spatiotemporal variations and future tendency of drought for the ecological environment in the Loess Plateau. Based on grid data of monthly precipitation and temperature from 1986 to 2019, we calculated standardized precipitation evapotranspiration index (SPEI) and drought frequency. The spatiotemporal patterns and its variations were analyzed at the seasonal and annual scales in the Loess Plateau using the Mann-Kendall test and Sen's slope estimation method. Finally, the future trend of drought was analyzed in the Loess Plateau by the NAR neural network combined with Hurst index. Results showed that the trend of aridification became more significant in the Loess Plateau, and that the frequency of droughts events exhibited great spatial variations at the interannual and seasonal scales during the study period. Specifically, the highest frequency of drought in the interannual, spring and winter was found in the southeast and west of the Loess Plateau, whereas the frequency of drought in summer and autumn was higher in the northwest. The frequency of moderate drought was the highest in summer compared with other seasons while the frequency of slight drought was the highest in interannual and other seasons. The Loess Plateau showed a trend of aridification in spring and summer, but this trend in autumn and winter became weaker in most areas of the study area. The SPEI value in the interannual, spring, and summer exhibited a decline trend in a future period in the Loess Plateau. The aridification would be enhanced. The Hurst index value was the largest and the persis-tence of its change remained stronger in summer. The possibility of continuous drought in summer would be higher than that in other seasons in the future.
Fibrolase is a non-hemorrhagic zinc metalloproteinase found in southern copperhead snake (
Agkistrodon contortrix contortrix
) venom that acts directly on fibrin clots and does not require ...plasminogen or any other blood-borne intermediate for activity. Chimeras of fibrolase with RGD peptides conferring antiplatelet activity have been synthesized covalently, but we describe a simpler, cheaper and less toxic method, using site-directed mutagensis. Fibrolase variants that constitute the arginine-glycine-aspartic acid (Arg–Gly–Asp, RGD) motif were constructed using site-directed mutagenesis. Chimeric genes of fibrolase were expressed in
Escherichia coli
to obtain the bifunctional chimeric molecule of fibrolase that can inhibit platelet aggregation. After refolding and purification, platelet-targeted thrombolysis and antiplatelet aggregation of the target chimeric protein were determined. The mutant RGD-F2, using the GPRGDWRMLG peptide to replace the TSVSHD sequence between sites 69 and 72, not only had almost the same catalytic ability as wild-type fibrolase but also a strong ability to inhibit platelet aggregation.
The undercooled Fe50Cu50 alloy experiences a metastable liquid phase separation and separates into a Fe-rich zone and a Cu-rich zone within the gravity field. The growth characteristics of the ...Cu-rich zone were investigated by the glass fluxing method, and the achieved undercooling range was 20−261 K. The volume fraction of the Cu-rich zone decreases with the enhancement of the bulk undercooling. The microstructural morphologies of the Cu-rich zone are similar at all the undercooling conditions, that is, αFe dendrites and particles are distributed inside (Cu) phase matrix. The secondary dendritic arm spacing of αFe dendrites decreases with the increase in bulk undercooling. The growth mechanism of αFe dendrites was analyzed by using the LKT/BCT dendritic growth theory. The dendritic growth in the Cu-rich zone is mainly controlled by solute diffusion so that the dendritic growth velocity is only several millimeters per second. Besides, the calculated results indicate that there is only inconspicuous solute trapping during the solidification of Cu-rich zone.
The undercooled Fe sub(50)Cu sub(50) alloy experiences a metastable liquid phase separation and separates into a Fe-rich zone and a Cu-rich zone within the gravity field. The growth characteristics ...of the Cu-rich zone were investigated by the glass fluxing method, and the achieved undercooling range was 20-261 K. The volume fraction of the Cu-rich zone decreases with the enhancement of the bulk undercooling. The microstructural morphologies of the Cu-rich zone are similar at all the undercooling conditions, that is, alpha Fe dendrites and particles are distributed inside (Cu) phase matrix. The secondary dendritic arm spacing of alpha Fe dendrites decreases with the increase in bulk undercooling. The growth mechanism of alpha Fe dendrites was analyzed by using the LKT/BCT dendritic growth theory. The dendritic growth in the Cu-rich zone is mainly controlled by solute diffusion so that the dendritic growth velocity is only several millimeters per second. Besides, the calculated results indicate that there is only inconspicuous solute trapping during the solidification of Cu-rich zone.
Background Environmental factors-induced dysfunction of esophageal squamous epithelium, including genomic DNA impairment and apoptosis, play an important role in the pathogenesis of esophageal ...squamous cell cancer. DNA damage-induced 45alpha (GADD45alpha) has been found promoting DNA repair and removing methylation marker, Therefore, in this study we will investigate whether GADD45alpha expression is induced and its mechanism in esophageal squamous cell cancer. Methods Two human esophageal squamous cell lines (ESCC), ECA109 and KYSE510 were cultured in RPMI-1640 medium supplemented with 10% fetal bovine serum (FBS). Lipofectamine 2000 was used to transfect cells. mRNA level of GADD45alpha was measured by reverse transcription-quantitive PCR (RT-qPCR), protein level of GADD45alpha was detected by western blot and Immunohistochemistry. Global DNA methylation of tissue sample was measured using the Methylamp Global DNA Methylation Quantification Ultra kit (Epigentek Group) and promoter methylation was measured by bisulfite sequencing. Results GADD45a mRNA and protein levels were increased significantly in tumor tissue than that in adjacent normal tissue. Hypomethylation of global genomic DNA and GADD45alpha promoter were found in ESCC. The cell sensitivity to Cisplatin DDP was decreased significantly in Eca109 and Kyse510 cells, in which GADD45alpha expression was down-regulated by RNA interference (RNAi). In addition, silence of GADD45a expression in ESCC cells inhibited proliferation and promoted apoptosis. Conclusion Overexpression of GADD45alpha gene is due to DNA hypomethylation in ESCC. GADD45alpha may be a protective factor in DDP chemotherapy for esophageal squamous cell carcinoma.
Purpose
This study assessed the concentrations of platinum (Pt) and palladium (Pd) in surface sediments and sedimentary cores collected from the Pearl River Estuary with a view of evaluating the ...distribution, background levels, possible sources, and contamination level of anthropogenic Pt and Pd.
Materials and methods
Thirty-six samples of surface sediments and 12 samples from sedimentary cores were collected. Al
2
O
3
was analyzed on fused glass disks by X-ray fluorescence spectrometer. Heavy metal elements were measured by inductively coupled plasma–mass spectrometry. Pt and Pd were separated from the sample matrix by anion exchange chromatography and subsequent solvent extraction after samples had been digested in Carius tubes using aqua regia. The analysis of Pt and Pd was performed by isotopic dilution-inductively coupled plasma-mass spectrometry.
Results and discussion
Pt and Pd concentrations in surface sediments were 0.28–2.11 and 0.39–38.30 ng/g, respectively, and Pt and Pd concentrations in sedimentary cores were 0.19–1.18 and 0.15–1.76 ng/g, respectively. Background values of Pt and Pd were 0.20–1.17 and 0.10–1.34 ng/g, respectively. The spatial distribution of the enrichment factor differed between Pt and Pd in surface sediments. Down-core variations in Pt, Pd, and other heavy metal elements were similar in all cases and were related to sediment type.
Conclusions
Some of the Pt and Pt in surface samples were derived from anthropogenic emissions. Pt and Pd were delivered to the sediment by fluvial input. In addition to vehicle exhaust catalysts, Pt and Pd were derived from other sources (e.g., industrial process). An important post-burial remobilization process of Pt and Pd is likely to be particle mixing by billows caused by typhoon.
Ancrod, a serine protease purified from the venom of Agkistrodon rhodostoma, is highly specific for fibrinogen. It causes anticoagulation by defibrinogenation and has been used as a therapeutic ...anticoagulant for the treatment of moderate to severe forms of peripheral arterial circulatory disorders in a variety of countries. The DNA of ancrod was amplified by recursive PCR with a yeast bias codon and cloned into the pGEM-T Easy vector. In order to achieve a high level secretion and a full activity expression of ancrod in Pichia pastoris (P. pastoris), the P. pastoris protein disulfide bond isomerase (PpPDI) was co-overexpressed in the strain. The secretion characteristics of ancrod with and without PpPDI were examined. With co-overexpression of PpPDI, the production of recombinant ancrod (rAncrod) was increased to 315mg/L in the culture medium, which is twofold higher than the control strain carrying only the ancrod gene. Through purified by Ni super(2+) affinity chromatography and phenyl Sepharose column, the purity of rAncrod was found to be as high as 95.2%. The fibrinogenolytic and zymographic activities of the rAncrod were determined and found to be similar to that of the native protein. This improved expression system can facilitate further studies and the industrial production of ancrod.
Background Tumor necrosis factor-α is a key mediator in the pathogenesis of psoriasis. Infliximab is a monoclonal antibody that specifically binds to tumor necrosis factor-α. The purpose of this ...study was to validate the efficacy and safety of 5 mg/kg infliximab therapy in Chinese patients with moderate to severe plaque psoriasis. Methods In this multicenter, double-blind, placebo-controlled trial, 129 patients with moderate-to-severe psoriasis were randomized to the induction therapy （weeks 0, 2 and 6） with infliximab 5 mg/kg （n=84） or placebo （n=45）, followed with infliximab 5 mg/kg scheduled at week 14 and week 22 in the infliximab group, and infliximab 5 mg/kg scheduled at weeks 10, 12 and 16 in the placebo group. The primary end point was the proportion of patients who achieved at least 75% improvement in Psoriasis Area and Severity Index （PASI 75 response rate） from baseline at week 10. Results At week 10, 81.0% of patients treated with infliximab （5 mg/kg） achieved a 75% or greater improvement compared with 2.2% of patients treated with placebo （P 〈0.001）. A significant improvement in PASI, Physician＇s Global Assessment （PGA） and Dermatology Life Quality Index （DLQI）, was seen from week 6 through week 14 in the infliximab group compared with the placebo group. Through week 22, PASI, PGA, DLQI were well maintained. The incidence of adverse events for the infliximab treatment group was slightly higher in comparison to the placebo treatment group during the first 10 weeks without statistical significance. However, there were 3 cases of tuberculosis that developed during the 26 weeks treatment with infliximal. Conclusions Infliximab treatment was effective as induction and maintenance treatments for Chinese patients with moderate to severe plaque psoriasis. Most drug-induced adverse events were mild to moderate, and well tolerated. Screening for tuberculosis is essential and prophylactic treatment should be given if necessary.
As for the separated air conditioner in the public is not facilitate for unified management and often causes a waste of energy, so we put forward a kind of centralized control system, which is ...suitable for small and medium-sized public places, to manage many separated air conditioner together. Through the development of the software VC++ and the communication with the internal 51-series microcomputer CPU of the air conditioner in many different rooms by using the bus RS485, we could realize the controlling of the turning on or off of the conditioner as well as the temperature and strength of the wind of the air conditioner centrally. The system is characterized for its highly safety performance and its ease to use.
Background： The pathogenesis of postural tachycardia syndrome （POTS） remains unclear. This study aimed to explore the changes and significance of sulfur dioxide （SO2） in patients with POTS. Methods： ...The study included 31 children with POTS and 27 healthy children from Peking University First Hospital between December 2013 and October 2015. A detailed medical history, physical examination results, and demographic characteristics were collected. Hemodynamics was recorded and the plasma SO2was determined. Results： The plasma SO2was significantly higher in POTS children compared to healthy children （64.0 ± 20.8 μmol/L vs. 27.2 ± 9.6 μmol/L, respectively, P 〈 0.05）. The symptom scores in POTS were positively correlated with plasma SO2levels （r = 0.398, P 〈 0.05）. In all the study participants, the maximum heart rate （HR） was positively correlated with plasma levels of SO2（r = 0.679, P 〈 0.01）. The change in systolic blood pressure from the supine to upright （ΔSBP） in POTS group was smaller than that in the control group （P 〈 0.05）. The ΔSBP was negatively correlated with baseline plasma SO2levels in all participants （r = ？0.28, P 〈 0.05）. In the control group, ΔSBP was positively correlated with the plasma levels of SO2（r = 0.487, P 〈 0.01）. The change in HR from the supine to upright in POTS was obvious compared to that of the control group. The area under curve was 0.967 （95% confidence interval： 0.928–1.000）, and the cutoff value of plasma SO2level 〉38.17 μmol/L yielded a sensitivity of 90.3% and a specificity of 92.6% for predicting the diagnosis of POTS. Conclusions： Increased endogenous SO2levels might be involved in the pathogenesis of POTS.
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