The in vitro inhibitory effect of human neutrophil peptide-1 on human immunodeficiency virus type 1

In order to clarify, the mechanism of inhibition of human neutrophil peptide-1 （ HNP-1 ） on hu- man immunodeficiency vires type 1 （HIV-1 ）, CD4^ ＋ cells were used as the target cells for acute infection with HIV-1, and experiments were peffomed separately with the interaction of different concentrations of HNP-1 with free vires particles, un-infected and infected CD4^＋ cells. The activity of reverse transcriptase （RT） in the supematant of cell cultures of different lots of experiments were then assayed accordingly, and the toxicity effect on human lymphocytic cells MT4 was measured by MTT assay. The experimental results showed that pre-incubation of HNP-1 with the concentrated stock of vires could block the binding of vires to target cells with EC50 of 2.49 μg/ml, while pre-treatment of CD4^＋ cells with HNP- 1 prior to inoculation could reduce the ability of cells to bind vires with EC50 of 20.7 μg/ml. In addition, When culturing the infected CD4^＋ cells in the continuous presence of various concentrations of HNP-1 added immediately after infection, HNP-1 exhibited modest inhibitory effect on viral replication with reduced RT activities in comparison with those of the control group （ P 〈 0.05 at 100 μg/ml of the highest concentration） . No cytotoxieity effect of HNP-1 was observed as demonstrated by MTT assay. These results indicate that HNP-1 exerts anti-HIV activity by at least two levels： direct inactivation of vires particles and effect on the ability of target cells to bind with viruses. The evaluation of two parameters, inhibitoty effect and the cytotoxicity renders HNP-1 an available candidate for anti-HIV therapeutic agent.

Comparative Analysis of a Jack-up Drilling Unit with Different Leg Systems

The jack-up unit is one of the best drilling platforms in offshore oil fields with water depth shallower than 150 meters.As the most pivotal component of the jack-up unit,the leg system can directly affect the global performance of a jack-up unit.Investigation shows that there are three kinds of leg structure forms in the world now:the reverse K,X,and mixing types.In order to clarify the advantage and defects of each one,as well as their effect on the global performance of the jack-up unit,this paper commenced to study performance targets ofa deepwater jack-up unit with different leg systems(X type,reverse K type,and mixing type).In this paper a typical leg scantling dimension and identical external loads were selected,detailed finite element snalysis(FEA)models were built to simulate the jack-up unit's structural behavior,and the multi-point constraint(MPC)element together with the spring element was used to deal with the boundary condition.Finally,the above problems were solved by comparative analysis of their main performance targets(including ultimate static strength,dynamic response,and weight).

Effect of martensitic transformation on nano/ultrafine-grained structure in 304 austenitic stainless steel

304 austenitic stainless steel was cold rolled in the range of 20%-80%reductions and then annealed at 700-900°C for 60 sto obtain nano/ultrafine-grained（NG/UFG）structure.Transmission electron microscopy,electron backscatter diffraction and X-ray diffraction were used to characterize the resulting microstructures.The results showed that with the increase of cold reduction,the content of martensite was increased.The steel performed work hardening during cold-working owing to the occurrence of strain induced martensite which nucleated in single shear bands.Further rolling broke up the lath-type martensite into dislocation-cell type martensite because of the formation of slip bands.Samples annealed at 800-960°C for 60 swere of NG/UFG structure with different percentage of nanocrystalline（60-100 nm）and ultrafine（100-500 nm）grains,submicron size（500-1000 nm）grains and micron size（〉1000 nm）grains.The value of the Gibbs free energy exhibited that the reversion mechanism of the reversion process was shear controlled by the annealing temperature.For a certain annealing time during the reversion process,austenite nucleated first on dislocation-cell type martensite and the grains grew up subsequently and eventually to be micrometer/submicrometer grains,while the nucleation of austenite on lath-type martensite occurred later resulting in nanocrystalline/ultrafine grains.The existence of the NG/UFG structure led to a higher strength and toughness during tensile test.