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In order to quickly obtain practical ship forms with good resistance performance, based on the linear wave-making resistance theory, the optimal design method of ship forms with minimum total resistance is discussed by using the non-linear programming (NLP) method. Taking the total resistance as the objective function (the Michell integral is used to calculate the wave-making resistance and the equivalent plate friction resistance formula is used to calculate the frictional resistance), the hull surface offset as the design variable and appropriate displacement as the basic constraints, and considering the additional constraints, the hull bow shape and the whole ship are optimised, and an improved hull form is obtained. The resistance of the ship before and after optimisation is calculated by the CFD method to further evaluate the resistance reduction effect and performance after optimisation. Finally, an example of optimisation calculation of an actual high-speed ship is given. The obvious resistance reduction results confirm the reliability of the optimisation design method
Protein kinase B (PKB/Akt) is a serine-threonine kinase functioning downstream of phosphatidylinositol 3-kinase (PI-3 kinase) in response to mitogen or growth factor stimulation. In several cell types, it plays an important anti-apoptotic role. TPA is a potent regulator of the growth of many different cell types. Here, we detected that TPA could induce cell apoptosis in the gastric cancer cell line, BGC-823. We also found that TPA inhibited the expression of PKB/Akt in a TPA concentration- and time-dependent manner. Furthermore, TPA inhibited the phosphorylation of PKB at Ser473, but did not affect the phosphorylation of Thr308. It only attenuated the expression of PKB/Akt and the phosphorylation of Ser473 in the cell nucleus, whereas it did not change the PKB/Akt distribution in BGC-823 cells. These results suggest that PKB/Akt inhibition by TPA may be the important factor in the mechanism of effect of TPA on gastric cell lines.
The PKB signaling pathway is essential for cell survival and the inhibition of apoptosis, but its functional mechanisms have not been fully explored. Previously, we reported that TPA effectively inhibited PKB activity and caused PKB degradation, which was correlated with the repression of PKB phosphorylation at Ser473. In this study, we focus on how PKB is regulated by TPA in gastric cancer cells. One of the TPA targets, PKCα, was found to mediate the inhibition of PKB phosphorylation and degredation caused by TPA. Furthermore, TPA induced the import of PKCα into the nucleus, where PKCα exerted an inhibitory effect on PKB expression and phosphorylation. As a result, cancer cell proliferation was arrested. Our study characterizes a novel function of PKCα in mediating the negative regulation of PKB by TPA, and suggests a potential application in the clinical treatment of gastric cancer.
The functionalized mesoporous’ potential ability of binding heavy metals using different templates, namely cetyltrimethylammonium (CTAB) (adsorbent A) and triblock copolymer (Pluronic P123, EO20PO70EO2O, Mav = 5800) (adsorbent B), was evaluated. The synthesized materials were characterized by powder X-ray diffraction (XRD), nitrogen gas sorption, FT-IR and solid-state ¹³C and ²⁹Si NMR spectroscopy and thermogravimetry (TGA) measurements. In the adsorption experiment, the effects of several variables (stirring time, pH and presence of other metals in the medium) were studied. On the basis of these results, it was observed that the adsorption capacities were higher for adsorbent B than adsorbent A. The results also confirmed that the ureido group (CO-NH₂) has a good affect of binding metal ion.
Through the combination subject of scientific research, the design method of the winch driven by contactless magnetic coupling is researched for the core purpose of the turning shaft sealing in a deepwater environment. This method has six design phases, including domestic and foreign information query and retrieval, graphic analyses of relevant structures, innovative design of 2D assembly sketches, a theoretical computation of structure parameters, the 3D modeling and motion simulation and engineering drawing. This method is of generality, which can provide examples for the postgraduate students and engineering personnel in self-renovation design of scientific research
When an offshore oil field completed and put into production, new subsea pipelines and the new cable need to be established. Cable protection pipe clamp is used to fix cable protection pipe on the jacket. In order to avoid the problem of traditional steel structure clamp splice, counterpoint, fastening difficulty when installed cable protection pipe under water, reduce the risk and workload of under water, This paper develop a new type of portable connecting riser clamp –“backpack clamp” which solve the riser cable protection pipe difficult underwater installation problem. The main structure of backpack clamp used three valves type structure. The load characteristic of a clamping device was determined by the Morison equation which was a classical theory. Clamp device underwater mechanics analysis model was established. The minimum tension pre-tightening force was determined. The results show that the strength of the base meets the requirements after strength analysis with finite element analysis method, stability and strength experiments, which means the clamp based on resin matrix composite is feasible
With the rapid development of the marine economy and continuous improvement of the industry, the scale of the offshore engineering is increasing. This raises interest in studying, theoretically and experimentally, gripping and bearing mechanisms for large-scale holding and lifting tools used in foundation pile installations. In this paper, the embedded gripping mechanism is studied based on the theory of elastic-plastic mechanics. The embedded and bearing performance of the tooth is simulated and the influence factors are studied. In addition, the device used in the simplified embedded experiment on the tooth of the embedded block is designed. The relationship between embedded depth, load, and tooth profile angle is identified and validated. Meanwhile, the embedded performance of linear and ring type teeth is compared experimentally in order to select the suitable type of tooth for various situations. This comparison makes the basis for designing an upending gripper for the marine pile foundation, which can realize the operation of holding the pile to prevent its falling
The reliability and safety of offshore platform are an important research aspect in marine engineering. The jacket platform is mainly used for oil development and submarine drilling, and the long-term work in the marine environment will be subjected to different loads, which will lead to the damage of the structure part of the offshore platform. It affects the structural strength of the platform. For the repair of jacket damage, grouted reinforcement technology is adopted, which has the advantages of simple underwater installation and low cost. The reinforcement technology of the grout hoop has been applied to the engineering projects abroad, but the stress and serialization design of the hoop in the marine environment need further study. This paper will combine the ocean current and wave force to carry out the research of underwater work and prevent loosening, and put forward the parametric design method for the specific size of the hoop. Two types of experimental models are designed: short bolt form clamp and long bolt form clamp. The mechanical experiment of the long bolt clamp is carried out, and the relationship between the slipping force and the bolt preload is analyzed, so as to verify the theoretical analysis
The expression of predominant housekeeping genes used in RT-qPCR can vary during development and differentiation. The frequently used housekeeping genes (ACTB, GAPDH, 18S rRNA, EF1α and RPL 13a) were evaluated during an early stage of the osteogenic differentiation of mouse bone marrow-derived mesenchymal stem cells (mMSCs) (under normal conditions or treated with CCG-4986) to identify housekeeping genes whose expression remained constant during osteogenic differentiation. When we used RGS4 mRNA, which was determined as copy number per μg of total RNA, to normalize gene expression, we observed that the relative EF1α expression profile was consistent with RGS4 expression after treatment with CCG-4986. All the relative expression profiles of the EF1α, 18S rRNA, and RPL13a housekeeping genes were consistent with RGS4 profiles determined by measuring mRNA copies under normal osteogenic differentiation conditions. The expression profiles calibrated by ACTB and GAPDH were not consistent with those determined using mRNA copy number in untreated cells or cells treated with CCG-4986 under osteogenic differentiation conditions. Under normal osteogenic differentiation conditions, EF1α, 18S rRNA, and RPL 13a are suitable housekeeping genes for RT-qPCR analysis. However, EF1α is the only suitable gene upon CCG-4986 treatment.
Water contamination poses serious threats to human health and is more prevalent in developing countries. A bio sand filter (BSF) is useful technology for developing nations because of its low cost and good treatment effi ciency. Being a locally available plant species, melia (Melia azedarach) biomass was used in BSF to test its effi ciency for metal and pathogen removal. Different concentrations (2~6 mg/L) of iron and lead and Escherichia coli-contaminated water were passed through a control sand filter (having no plant biomass) and BSF. The results showed that all three contaminants had higher removal rates in the BSF compared to the control sand filter. The removal of E.coli reached up to 100 percent on some days in the BSF, which was not the case with the control sand fi lter. The percent removal of Fe and Pb in BSF was 97.9~99.9% and 31~61%, respectively. Signifi cant turbidity removal was also observed in BSF. Melia biomass is a useful bio-resource that can help to improve water quality in BSF.
Although the fertilization effect on soil microbial communities have been studied extensively, its influence combined with plastic-film mulching on seasonal variations of bacterial communities remains unknown. High throughput sequencing was used to explore seasonal bacterial communities in a longterm fertilization experiment that commenced in 1987. Non-fertilization and the application of manure combined with nitrogen fertilization significantly (P<0.05) increased bacterial abundance at phylum level without film mulching in July and with film mulching in October. Also, the relative abundance of dominant bacterial groups in October exceeded those in July. Nitrogen fertilization (N) significantly (P<0.05) decreased soil bacterial diversity and richness with or without film mulching compared to nonfertilization controls during July and October. Plastic film mulching and long-term manure fertilization significantly (P<0.05) increased bacterial diversity and richness as well as the relative abundance of dominant bacterial groups. Statistical analysis revealed that soil pH was the main driving force influencing bacterial groups. In conclusion, our results highlight the relative importance of long-term application of manure fertilization and plastic film mulching on seasonal variations of bacterial diversity and structure. This finding also highlights the relevance of soil pH as the main deterministic abiotic factor for soil bacterial community structure regardless of film mulching.
Potassium (K+) is an essential macronutrient for plant growth, development, and fruit quality and yield. K+ uptake and transport is facilitated by KT/HAK/KUP transporters. However, studies to establish molecular mechanisms are rare in fruits, especially in peaches. In this study, we isolated 16 putative KT/HAK/KUP transporter genes in peach, and analyzed K+ homeostasis status in relation to KUP (K+ uptake) gene expression during whole fruit development life. The ‘Xiahui6’ peach development was divided into four distinct stages, S1–S4, and fruits were harvested on 110 days after full bloom (DAFB). QRTPCR results showed that PpeKUP genes unevenly existed in various fruit parts and are differentially expressed during fruit development, ripening, and postharvest storage. The most highest-expressed gene was PpeKUP1 in mesocarp and PpeKUP2 in skin, especially during early stages, while PpeKUP3 was steadily expressed even until postharvest shelf-life. After harvest, the flesh firmness was nonsignificantly changed under cold treatment (4 C), to avoid ripening. Notably, five PpeKUP genes were responsive to cold treatment as their expression were mainly induced in skin, except for PpeKUP3 that was decreased in both mesocarp and skin. Moreover, functional determination showed that PpeKUP1 and PpeKUP2 are important K+ transporters that mediate K+ uptake and accumulation, especially during fruit formation and fast growth stages. This study reveals a close relationship among peach growth, firmness maintenance, and K+ homeostasis, and directly provides potential candidate genes for further molecular studies.
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