直升机用高均质性钢材及其标准分析

介绍了直升机用高均质性钢的设计要求和应用特点,分析了高均质性钢国内外标准的主要技术要求和质量保证规定,提出了今后直升机用高均质性钢的纳标建议和方案。

高碾压式均质土坝坝体排水设施的设计与施工

北疆某水库大坝为碾压式均质土坝,具有坝线长,最大坝高高的特点。为保证坝体形成稳定渗流后,排水设施能够充分发挥作用,设计上采用了竖式排水、水平褥垫式排水、坝脚排水棱体相结合的综合布置型式,施工中采用了"档板法"的填筑工艺。从运行效果来看,排水设施作用明显,及时排除了坝体及坝基渗水,有效降低了防渗体孔隙水压力,保证了大坝的安全运行。

纳米钨镍铁复合氧化物粉的新法制备

研究制备了分散均匀的纳米W-Ni-Fe复合盐.以化学共沉淀法制备的盐在600℃下氧化,可得W-Ni-Fe复合氧化物,检测分析显示W-Ni-Fe复合氧化物粉的晶粒直径XRD-d为36 nm,W-Ni-Fe复合氧化物粉的颗粒粒径BET-d为98 nm;从SEM图分析看出该复合氧化物粉颗粒团聚性低,压坯EDXS的表面电子图像和元素面分布图显示该复合氧化物粉中W、Ni、Fe元素分布状态是高度均匀分布.

Red Clay Sediment in the Central Chinese Loess Plateau and Its Implication for the Uplift of the Tibetan Plateau

The widely distributed red clay sediment underlying the Chinese Loess Plateau truly records the Neogene environmental evolution, and its genesis and development are intrinsically related to the uplift processes of the Tibetan Plateau and the evolution of East Asia monsoon system. In this paper, a detailed magnetostratigraphy of a loess-red clay section （107°13′E, 35°02′N） from the central Loess Plateau is reported. The loess-red clay sequence is composed of 175 m Quaternary loess-paleosol sequence and 128 m Neogene red clay sediments. Based on the correlation with the standard geomagnetic polarity time scale, the paleomagnetic results indicate that the age of Chaona red clay sequence extends to 08.1 Ma, which is the older red clay deposition in the central Chinese Loess Plateau. The commencement of red clay at -8.1 Ma may imply that the Ordos planation surface was broken by the movement of the Haiyuan-Liupanshan Faults, which was related to the uplift of the Tibetan Plateau induced by the collision of India Plate and Eurasian Plate. And the western part adjacent to the Tibetan Plateau was uplifted to form the embryo of the Liupan Shan （Mts.） and the eastern part was down-faulted to receive red clay deposition. We link this faulting to an initial uplift of the Tibetan Plateau. The undulating nature of the broken Ordos planation surface may explain the chronological differences and depth discrepancies among various cross-sections of red clay.

Remaining oil distribution in models with different heterogeneities after CO_(2) WAG injection:Visual research by nuclear magnetic resonance technique

Water alternating gas(WAG)injection is a widely used strategy for enhancing oil recovery(EOR)during gas flooding,and the mechanisms,operating parameters,and influencing factors of which have been extensively studied.However,with respect to its capacity in expanding macroscopic sweep volume under varying heterogeneities,the related results appear inadequate.In this research,three cores with different heterogeneities were used and flooded by the joint water and CO_(2) WAG,then the effects of heterogeneity on oil recovery were determined.More importantly,the cores after CO_(2) WAG injection were investigated using the nuclear magnetic resonance(NMR)technique for remaining oil distribution research,which could help us to understand the capacity of CO_(2) WAG in enlarging sweep volume at different heterogeneities.The results show that the presence of heterogeneity may largely weaken the effectiveness of water flooding,the more severe the heterogeneity,the worse the water flooding.The WAG injection of CO_(2) performs well in EOR after water flooding for all the cores with different heterogeneities;however,it could barely form a complete or full sweep throughout the low-permeability region,and un-swept bypassed regions remain.The homogeneous core is better developed by the injection of the joint water and CO_(2) WAG than the heterogeneous and fractured cases.

Nutrient uptake by mulberry and Chinese prickly ash associated with arbuscular mycorrhizal fungi

Understanding how nutrient absorption processes in plants are related to arbuscular mycorrhizal(AM)association is critical for predicting the effects of AM symbiosis on elemental cycling for plants. Both mulberry(Morus alba) and Chinese prickly ash(Zanthoxylum bungeanum) are AM-associated plants, widely distributed in southwest China. It was hypothesized that if the nutrient absorption processes were efficiently associated with AM symbiosis in both mulberry and Chinese prickly ash, foliar nutrient concentrations—especially calcium(Ca)—would be primarily determined by the soil conditions in different regions. To investigate this, AM colonization levels of soils, nutrient levels in soils and leaves, and δ^(13)C values of leaves were analyzed for mulberry and Chinese prickly ash.In this study, spore density in soils with low p H was higher than that in soils with high p H. The average concentrations of sugar delivered to roots in both mulberry and Chinese prickly ash in soil with relatively low p H and soil extractable cations were higher than those in other areas.The values of foliar δ^(13)C in both mulberry and Chinese prickly ash in low soil-pH and soil extractable cations were lower than those in contrast areas, indicating that water availability was impacted by soil characteristics. The efficiency in AM-mediated processes might play an important role in translocation between soil nutrients and plant tissue.The results suggest uptake and translocation of nutrients,especially Ca, in AM-associated plants may be affected by an efficiency of AM-mediated processes. Since Sr does not appear to be similarly affected, expressing Ca and other nutrient concentrations relative to Sr could be used to evaluate whether the uptake and translocation of Ca and other nutrients are affected by AM-mediated processes.

Impacts of High Fiber Diet on Digestion and Absorption of Minerals in Growing Pigs

The study was conducted to investigate the effects of feeding high-fiber diet （HFD） on apparent total tract digestibility （ATTD） and absorption of minerals in growing pigs. Sixteen barrows averaging 16.39 kg were randomly assigned to one of four diets after metabolic crate assignment with individual pig serving as experimental unit. Diets include： a corn-soybean meal based low-fiber diet （LFD）, as the control （CON） and 3 HFD （D1, D2 and D3）, each containing 5% sugar beet pulps and a 1：2, 1：1 and 2：1 oats to barley ratios, respectively, replacing 47% of the corn in the diet. Diets were formulated to meet nutrient requirements, however, the fiber content of the LFD was substantially lower than the average of the HFD （8.38% vs. 22.40%）. Feed allowance was limited to 10% of average body weight and fed twice/d. The study period was divided into 10 d of adjustment and 5 d of feces collection. Data collected were analyzed using SAS, GLIMMIX procedure where animals were considered random effects, and minerals were fixed. Results of the study show that digestibility of Ca in pigs fed HFD was lower （P 〈 0.05） than in pigs fed LFD. On the other hand, the apparent digestibility of P, K, Na, S and Zn in pigs fed D2 and D3 were higher （P 〈 0.05） than in pigs fed CON diet. It was also observed that digestibility of Ca, P, K, Na, S and Zn in pigs fed D1 were lower （P 〈 0.05） than in CON, D2 or D3 fed pigs. Therefore, it was concluded that while feeding HFD reduced availability of Ca, the availability of P, K, Na and S to pigs improved as the oat to barley ratio in the diet increased.

Preparation,characterization and pharmacokinetics of 10-hydroxycamptothecin nanosuspension

10-Hydroxycamptothecin （HCPT） is a broad-spectrum anticancer drug, while its low solubility and instability severely limit its application. In this study, HCPT nanosuspension （HCPT-NSP）, also known as nanocrystal, was prepared by micro-precipitation combined with high-pressure homogenization method. This nanosuspension was characterized by size, shape, zeta potential, drug loading efficiency and in vitro drug release behavior. Preferred formulation and process showed that particle size was （129.8±13.9） nm, PDI was 0.20±0.07, and drug loading efficiency was 36.5%±9.5%. Moreover, HCPT nanocrystal concentration reached （1.35±0.2） mg/mL in HCPT-NSP, which was more than 1000-fold higher than that of HCPT. Transmission electron microscopy （TEM） results showed that the nanosuspension was short rod in shape. X-ray powder diffraction （XRD）, thermogravimetric analysis （TGA）, derivative thermogravimetric analysis （DTA） and differential scanning calorimetry （DSC） further elaborated the crystal state of the HCPT. The drug concentration-time curve of HCPT-NSP in rats was in accordance with the three-compartment model, showing prolonged half-life. Taken together, our data suggested that HCPT-NSP was a promising drug delivery system.

Preparation, characterization and pharmacokinetic studies of total paeony glycoside nanocrystals

Total paeony glycoside（TPG） is obtained from Radix Paeoniae Rubra with a variety of bioactivities. However, the low solubility and bioavailability limit its application. The present study aimed to develop TPG nanocrystals to increase the dissolution and then improve the oral bioavailability. TPG nanocrystals were prepared via precipitation and high-pressure homogenization method. The physical-chemical properties of the optimal TPG nanocrystals in terms of particle size, zeta potential, morphology and crystallinity were evaluated. The results showed that TPG nanocrystals had a mean particle size of（210.2±2.5） nm, a polydispersity index of 0.191±0.033 and a zeta potential of（–22.4±1.2） mV. The result of differential scanning calorimetry showed that the nanocrystals were still in crystalline state after the preparation procedure. Transmission electron microscopy（TEM） results showed that the nanosuspension was in spherical shape. The pharmacokinetics of TPG nanocrystals for rats was investigated by liquid chromatography-tandem mass spectroscopy（LC-MS/MS）. Compared with the TPG coarse suspension, TPG nanocrystals exhibited significant increase in AUC0–∞（approximately 1.85-fold）. Taken together, TPG nanocrystals could be used as a promising drug delivery system due to the enhanced oral bioavailability of TPG.

Shock relations in gases of heterogeneous thermodynamic properties

Shock relations usually found in literatures are derived theoretically under the assumption of homogeneous thermodynamic properties, i.e., constant ratio of specific heats, γ. However, high temperature effects post a strong shock wave may result in thermodynamic heterogeneities and failure to the original shock relations. In this paper, the shock relations are extended to take account of high-temperature effects. Comparison indicates that the present approach is more feasible than other analytical approaches to reflect the influence of γ heterogeneity on the post-shock parameters.

Effect of hydration on the elasticity of mantle minerals and its geophysical implications

Recent studies have shown that major nominally anhydrous minerals in the Earth's mantle, such as olivine, pyroxene and garnet, can incorporate considerable amounts of water as structurally bound hydroxyl. Even a small amount of water is present in mantle minerals, it can strongly affect a number of physical properties, including density, sound velocity, melting temperature, and electrical conductivities. The presence of water can also influence the dynamic behavior, lead to lateral velocity heterogeneities, and affect the material circulation of the Earth's deep interior. In particular, seismic studies have reported the existence of low-velocity zones in various locations of the Earth's upper mantle and transition zone, which has been expected to be associated with the presence of water in the region. In the past two decades, the effect of water on the elasticity and sound velocities of minerals at relevant pressure-temperature(P-T) conditions of the Earth's mantle attracted extensive interests. Combining the high P-T experimental and theoretical mineralogical results with seismic observations provides crucial constraints on the distribution of water in the Earth's mantle. In this study, we summarize recent experimental and theoretical mineral physics results on how water affects the elasticity and sound velocity of nominally anhydrous minerals in the Earth's mantle, which aims to provide new insights into the effect of hydration on the density and velocity profile of the Earth's mantle, which are of particular importance in understanding of water distribution in the region.

Relationship between heterogeneity of source rocks and genetic mechanism of abnormally high pressure

Based on the micro-fluorescence observation of polished sections of source rocks,two types of micro-layers with different wetting properties formed in thermal evolution,i.e.,oil-wetting and water-wetting micro-layers,are distinguished.The wetting property is found closely related to the abundance of organic matter and its occurrences with inorganic minerals.The alternating distribution and intercrossing of two types of micro-layers formed many separated spaces with different wettabilities.The strong capillary forces in these separated spaces with different wettibilities obstruct the cross flows of pore fluids and result in nearly independent and closed fluid systems.As a consequence,these spatially superposed spaces in source rocks bear the overburden pressure and then abnormally high pressures have developed in the whole source rock unit.Therefore,the abundance and occurrences of organic matter are the main inner factors influencing the formation of abnormally high pressures,whereas the formation,distribution and development of micro-layers with different wettabilities during the evolution of source rock determine the intensity and spatial distribution of abnormally high pressures.