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Numerical simulations were carried out to explore the flow characters and swirl distortion features of RAE M2129 S-Duct inlet using detached eddy simulation. Three freestream conditions at Mach 0.21, at angle of attack between 0 and 12 deg and at angle of sideslip between 0 and 12 deg are simulated. Results suggest that the time-averaged flow features and the aerodynamic performance of the S-Duct inlet for three freestream conditions are similar to each other; meanwhile, the time-averaged swirl distortion descriptors are also close to each other. Nevertheless, the instantaneous small-scale turbulent structures primarily induced by the freestream angle of attack lead to the generation of more strong vortices at the inlet exit plane between inlet center cone and the stbd wall, which results in larger fluctuating swirl distortions. Furthermore, the fluctuating velocity in transverse direction is more positively correlated with circumferential velocity, while the fluctuating velocity in longitude direction is more negatively correlated with circumferential velocity. [ABSTRACT FROM AUTHOR]

It is well known that land use change can affect soil C storage of terrestrial ecosystems either by altering the biotic processes involved in carbon cycling or by altering abiotic processes such as carbon adsorption on soil minerals. Relatively few studies, however, have examined the dynamics of soil C pools after conversion of farmland to forest or pasture. We selected three pairs of secondary forests and pastures that originated from the same abandoned sugarcane (interspecific hybrids of Saccharum spp.) land in the wet tropics of Hawaii to examine whether forest or pasture converted from farmland is more effective in sequestering C in soils. We compared the soil C pool, soil chemistry, and stable C isotope ratios between the forests and pastures. We found that total soil C was greater ( P < 0.01) in forests than in the pastures 22 years after land conversion. The percentages of SOC in the pastures were significantly higher than in the secondary forests in both soil layers. The percentages of SOC in the pastures were lower than in the secondary forests in both soil layers. The net SOC increase in the forest soils at 0–10 and 10–25 cm was 28.6 ± 5.6 and 43.9 ± 3.2 Mg ha while net SOC increase in pasture soils at these respective depths was 18.8 ± 2.2 and 26.1 ± 2.7 Mg ha. We found that the net increases of SOC in both soil layers in the forest were greater ( P < 0.01) than the net increases of SOC in the respective soil layers in the pasture. Aluminum saturation was greater ( P < 0.01) in the forests than the pastures in both soil layers. There was no difference in oxalate extractable Fe concentration between the forests and the pastures but oxalate extractable Al concentration in both soil layers was greater ( P < 0.05) in forests than the pastures. Our findings indicated that reforestation of abandoned sugarcane farmland in Hawaii is more effective in soil C increase and stabilization than conversion to pasture. [ABSTRACT FROM AUTHOR]

We examined the correlation between fungal and bacterial biomass, abiotic factors such as soil moisture, carbon in the light soil fraction and soil nitrogen to a depth of 0–25 cm and heterotrophic soil respiration using a trenching technique – in a secondary forest ( Myrcia splendens, Miconia prasina and Casearia arborea) and a pine ( Pinus caribeae) plantation in the Luquillo Experimental Forest in Puerto Rico. Soil respiration was significantly reduced where roots were excluded for 7 years in both the secondary forest and the pine plantation. Microbial biomass was also significantly reduced in the root exclusion plots. In root exclusion treatment, total fungal biomass was on average 31 and 65% lower than the control plots in the pine plantation and the secondary forest, respectively, but the total bacterial biomass was 24 and 8.3% lower than the control plots in the pine plantation and the secondary forest, respectively. Heterotrophic soil respiration was positively correlated with fungal biomass ( R 2=0.63, R 2=0.39), bacterial biomass (R2=0.16, R 2=0.45), soil moisture ( R 2=0.41, R 2=0.56), carbon in light fraction ( R 2=0.45, R 2=0.39) and total nitrogen ( R 2=0.69, R 2=0.67) in the pine plantation and the secondary forest, respectively. The regression analysis suggested that fungal biomass might have a greater influence on heterotrophic soil respiration in the pine plantation, while the bacterial biomass might have a greater influence in the secondary forest. Heterotrophic soil respiration was more sensitive to total N than to carbon in the light fraction, and soil moisture was a major factor influencing heterotrophic soil respiration in these forests where temperature is high and relatively invariable. [ABSTRACT FROM AUTHOR]

The eúkaryotic expression of human arresten gene and its effect on the proliferation of iń vitro cultured vascular smooth cells (VSMCs) in vitro were investigated. COS-7 cells were transfected with recombinant eukaryotic expression plasmid pSecTag2-AT or control plasmid pSecTag2 mediated by liposome. Forty-eight h after transfection, reverse transcription-polymerase chain reaction (RT-PCR) was used to detect the expression of arresten mRNA in the cells, while Western blot assay was applied to detect the expression of arresten protein in concentrated supernatant. Primary VSMCs from thoracic aorta of male Sprague-Dawley rats were cultured using the tissue explant method, and identified by immunohistochemical staining with a smooth muscle-specific anti-α-actin monoclonal antibody before serial subcultivation. VSMCs were then co-cultured with the concentrated supernatant and their proliferation was detected using Cell Counting Kit-8 (CCK-8) in vitro. The results showed that RT-PCR revealed that the genome of arresten-transfected cells contained a 449 bp specific fragment of arresten gene, suggesting the successful transfection. Successful protein expression in supernantants was confirmed by Western blot. CCK-8 assay showed that the proliferation of VSMCs were inhibited significantly by arresten protein as compared with control cells ( F=40. 154, P<0. 01). It was concluded that arresten protein expressed in eukaryotic cells can inhibit proliferation of VSMCs effectively in vitro, which would provide possibility to the animal experiments. [ABSTRACT FROM AUTHOR]

We examined the effects of root and litter exclusion on the rate of soil CO2 efflux and microbial biomass using trenching and tent separation techniques in a secondary forest (SF) and a pine (Pinus caribaeaMorelet) plantation in the Luquillo Experimental Forest in Puerto Rico. Soil surface CO2 efflux was measured using the alkali trap method at 12 randomly-distributed locations in each treatment (control, root exclusion, litter exclusion, and both root and litter exclusion) in the plantation and the SF, respectively. We measured soil CO2 efflux every two months and collected soil samples at each sampling location in different seasons to determine microbial biomass from August 1996 to July 1997. We found that soil CO2 efflux was significantly reduced in the litter and root exclusion plots (7-year litter and/or root exclusion) in both the secondary forest and the pine plantation compared with the control. The reduction of soil CO2 efflux was 35.6% greater in the root exclusion plots than in the litter exclusion plots in the plantation, whereas a reversed pattern was found in the secondary forest. Microbial biomass was also reduced during the litter and root exclusion period. In the root exclusion plots, total fungal biomass averaged 31.4% and 65.2% lower than the control plots in the plantation and the secondary forest, respectively, while the total bacterial biomass was 24% and 8.3% lower than the control plots in the plantation and the secondary forest, respectively. In the litter exclusion treatment, total fungal biomass averaged 69.2% and 69.7% lower than the control plots in the plantation and the secondary forest, respectively, while the total bacterial biomass was 48% and 50.1% lower than the control plots in the plantation and the secondary forest, respectively. Soil CO2 efflux was positively correlated with both fungal and bacterial biomass in both the plantation the secondary forest. The correlation between soil CO2 efflux and active fungal biomass was significantly higher in the plantation than in the secondary forest. However, the correlation between the soil CO2 efflux and both the active and total bacterial biomass was significantly higher in the secondary forest than in the plantation in the day season. In addition, we found soil CO2 efflux was highly related to the strong interactions among root, fungal and bacterial biomass by multiple regression analysis (R2>0.61,P<0.05). Our results suggest that carbon input from aboveground litterfall and roots (root litter and exudates) is critical to the soil microbial community and ecosystem carbon cycling in the wet tropical forests. [ABSTRACT FROM AUTHOR]

In order to study the expression of transformation suppressor gene RECK and MMP-9 in hilar cholangiocarcinomas and its clinical significance, and explore the roles of RECK gene in metastasis and invasion of hilar cholangiocarcinoma, the expression levels of RECK, and MMP-9 mRNA were detected by using reverse transcription-polymerase reaction in 42 paraffin-embedded samples of hilar cholangiocarcinoma and 10 samples of benign bile duct diseases. The results showed that in hilar cholangiocarcinoma tissues, the expression of RECK gene was 0.235±0.062, significantly lower than in normal bile duct tissue (0.533±0.024, P<0.05). In hilar cholangiocarcinoma tissues, the expression of MMP-9 (0.528±0.039) was significantly higher than in the normal tissues (0.311±0.032, P<0.05). The expression of RECK gene was closely related to the intrahepatic and surrounding organs invasion ( P<0.05). It was concluded that RECK gene could inhibit the expression of MMP-9 in hilar cholangiocarcinomas and closely correlated with the biological behaviors. The abnormal expression of RECK gene might be one of the molecular mechanisms of hilar cholangiocarcinoma metastasis. [ABSTRACT FROM AUTHOR]

The anti-tumor effect and mechanism of the staphylococcal enterotoxin A (SEA) were studied. The mouse gastric tumor model was produced by subcutaneously inoculating gastric tumor cells (MGC80-3). The experimental group was treated with SEA, and the control group was treated with normal saline. The percentage of tumor generation and tumor mass was measured. The results showed that the percentage of the tumor generation in the SEA-treated mice was lower than in the control group, but there was no significant difference ( P>0.05). However, the tumor mass in the experimental group was significantly lighter than in the control group, with the difference being very significant ( P<0.001). There were more CD T cells and CD T cells in the tumor of the mice treated with SEA than those of the control group. SEA has an obvious anti-tumor effect on mice gastric tumor. The mechanism might be that SEA induces the effect of superantigen-dependent cell mediated cytotoxicity to the tumor cells. [ABSTRACT FROM AUTHOR]