Effect of stocking density on water quality and (Growth,Body Composition and Plasma Cortisol Content) performance of pen-reared rainbow trout (<Emphasis Type="Italic">Oncorhynchus mykiss</Emphasis>)

The goal of the study was to examine the effect of stocking density on the water quality of culture area, as well as the growth, body composition and cortisol content of rainbow trout（Oncorhynchus mykiss）. Pen-reared trout were stocked in densities of 40, 60, 80 fish individuals m^-3(4.6, 6.6, 8.6 kg m^-3, SD1, SD2 and SD3 groups, respectively) for 300 days. Compared to the water from SD1 and SD2, that from SD3 exhibited significantly higher NH₄⁺-N content and COD（chemical-oxygen-demand）, and a significant reduction of dissolved oxygen in day 180(40.6 kg m^-3). Stocking density was significantly associated with body weight, standard length, VSI（viscerosomatic index）, CF（condition factor） and FC（food coefficient） in group SD3, particularly in day 240 and day 300(45 or 49.3 kg m^-3). Increased crude fat and decreased crude protein were displayed in high density group when the density reached to 36 kg m^-3. As a cumulative effect of density-related stress, VSI, CF, FC, moisture, and crude protein content varied over time in each density group（SD1, SD2, and SD3）. In summary, trout exhibited a better growth performance in low density(26.3 kg m^-3) than those reared in high densities(36 and 45 kg m^-3). The results indicate that rainbow trout（114.44 g ± 6.21 g, 19.69 cm ± 0.31 cm） initially stocked in 6.6 or 8.6 kg m^-3 should be lightened to less than 36 kg m^-3 after an intensive rearing for 240 days.     

深海液压主从式机械手控制器

深海主从式机械手控制器是一个比较复杂的系统,可靠性要求高.分析了美国Schilling机械手的特点,介绍了研制的一台6自由度的机械手控制器的硬件电路和软件算法.该控制器运行稳定.机械手动作精度、速度满足使用要求.     

BALLOON-BORNE MEASUREMENTS OF AEROSOL VERTICAL DISTRIBUTIONS OVER BEIJING DURING THE SUMMER AND AUTUMN OF 1993

The results of two balloon soundings during the summer and autumn of 1993 from the Xianghe Observation Station are being utilized in a study of the temporal and spatial distribution of the atmospheric aerosols.The balloon,gondola,instrumentation and atmospheric conditions during the observation period are described.The temporal and spatial characteristics of aerosol concentration,size ratio,mixing ratio,and size distribution for both troposphere and strato-sphere are presented and analyzed.     

Behavior of REE Fractionation during Weathering of Dolomite Regolith Profile in Southwest China

<正>REE fractionation during the weathering of dolomite has been recognized for decades.A regolith profile on dolomite in southwest Yunnan of China was selected to investigate the behaviors of REE during weathering.The weathering of dolomite is divided into two stages:the pedogenesis stage and soil evolution stage,corresponding to the saprolites and soils respectively in the regolith profile. SiO_2,TiO_2,P_2O_5,Zr,Hf,Nb and Ta were immobile components during the weathering by and large, while Al_2O_3,K_2O and Fe_2O_3 were lost during the soil evolution stage in the physical form(clay minerals probably).REE were fractionated during the whole weathering of dolomite.The field weathering profile and the lab acid-leaching experiments on dolomite indicate that MREE were enriched clearly relative to other REE during the pedogenesis stage in a "capillary ascending-adsorption" mechanism, but they did not fractionate clearly in the soil evolution stage.REE were lost and accumulated in the weathering front of dolomite during the soil evolution stage in a "physical-chemical leaching" mechanism.     

A Preliminary Review of Metallogenic Regularity of Silver Deposits in China

China has widely distributed silver deposits,and is rich in silver resources.Although silver deposits are mainly associated with Pb-Zn deposits,a number of independent silver deposits have also been discovered in recent years.Silver deposits include different types,such as submarine volcanism and continental volcanism related type,intrusion related type,and sedimentary related type.This study summarized the metallogenic regularity of China’s silver deposits systematically based mainly on the data from 490 silver deposits.It is shown that submarine volcanic sedimentary type,continental volcanic or sub-volcanic type,skarn type,hydrothermal type(including vein type and stratabound type),sedimentary metamorphic type,sedimentary type and regolith type should be regarded as the most important prediction types of silver deposit.A total of 32 silver mineralization belts and 111 silver concentration areas have been delineated.The map of "Spatial distribution of silver mineralization belts in China" and other series of maps finished in this study may provide a theoretical basis for the evaluation and prognosis of silver resources potential in China.     

Seismic safety assessment with non-Gaussian random processes for train-bridge coupled systems

Extensive high-speed railway(HSR) network resembled the intricate vascular system of the human body,crisscrossing mainlands. Seismic events, known for their unpredictability, pose a significant threat to both trains and bridges,given the HSR’s extended operational duration. Therefore, ensuring the running safety of train-bridge coupled(TBC) system,primarily composed of simply supported beam bridges, is paramount. Traditional methods like the Monte Carlo method fall short in analyzing this intric...     

Reclassification of the Meso- and Neoproterozoic Chronostratigraphy of North China by SHRIMP Zircon Ages

Abstract: High-quality zircon U-Pb ages acquired from Meso- and Neoproterozoic strata in North China in recent years has provided a high-resolution chronostratigraphic framework for dating. A basis of this high-level chronostratigraphic system provides the foundation for a global Precambrian study and stratigraphic correlation and so recent geological studies have focused attention on systemic SHRIMP zircon dating. A chronology of Meso- and Neoproterozoic strata and the time of origin of the overlying Changcheng System is given on the basis of new SHRIMP zircon dating from the Qianxi Complex and diabase of the Chuanlinggou Formation. A new tectonostratigraphy for a Neoproterozoic chronostratigraphic framework in the southeastern margin of the North China continent is underpinned by the new SHRIMP zircon dating of a Neoproterozoic mafic magma diabase in the Jiao-Liao-Xu-Huai Sub-Province.     

Detrital Zircon Dating of Meso- and Neoproterozoic Rocks in North China and Its Implications

New dates from Meso- and Neoproterozoic strata contribute to the recently defined Precambrian stratigraphical timescale of China agreed by the Subcommission on the Precambrian System, and the National Commission on Stratigraphy of China on Nov. 24, 2009. First, the age range of the Changcheng System, including the Changzhougou, Chuanlinggou, Tuanshanzi and Dahongyu formations has been constrained to 1.8–1.6 Ga. Second, the Jixian System including the Gaoyuzhuang, Yangzhuang, Wumishan, Hongshuizhuang and Tieling formations has been constrained to 1.6–1.4 Ga. Third, an as-yet unnamed (undefined) system (1.4–1.0 Ga) is only developed in the Xiamaling Formation at the Jixian section, Tianjing. Fourth, the Qingbaikou System, including the Luotuoling and Jing’eryu formations has been constrained to 1.0–0.78 Ga. Fifth, the Nanhuan System ranges between 780–635 Ma, and the Sinian System is within 635–542 Ma. However, according to a series of SHRIMP U-Pb dates from the late Precambrian in the Jiangnan Orogen Belt in South China Platform, the constrained strata will be redefined as in the upper part of the Qingbaikou System. To aid global geodynamics, it is useful to denote a late Precambrian section with unified, precise and high-precision chronological dating; this is here defined in North China Block and Jiaoliao-Korean Block. However, the Neoproterozoic Qingbaikou study in North China will be influence in whole Meso- and Neoproterozoic in the Jiangnan Orogenic Belt in between the Yangtze Block and the Cathaysia Block in South China.