Extraction of agar from Eucheuma cottonii and Gelidium amansii seaweeds with sonication pretreatment using autoclaving method

The effect of sonication pretreatment condition on Eucheuma cottonii and Gelidium amansii seaweed towards agar extraction wae studied. Four parameters were changed during sonication to investigate the effects on agar yield and quality. These parameters include the time interval, concentration ratio, frequency, and intensity. The highest amount of agar extracted from Eucheuma cottonii species could be obtained from the time interval of 30 min, seaweed weight to solvent volume ratio of 1:20, the frequency of 35 Hz, and the sonication power intensity of 30%. For Gelidium amansii species, the best agar yield also could be obtained from the time interval of 30 min, 1:20 of seaweed weight to water volume ratio, the frequency of 35 Hz, and power intensity of 30%. From the experiment, sonication pretreatment significantly influenced the yield and properties of extracted agar. The sonication with autoclaved seaweed produced agar containing less sulfate content, which is an excellent chemical property for gel electrophoresis applications.The gel strength of sonication with autoclaving for both seaweeds, Eucheuma and Gelidium species was the highest among those by sonication with direct heating, which proved that sonication pretreatment with autoclaving could enhance the physical properties of the agar.     

人工聚沙堤防治铁路沙害的初期试验研究

本文介绍了在高寒干旱的青藏铁路线伏沙梁地段,采用人工聚沙堤阻截外来风沙流的试验。通过初期试验观测,对人工聚沙堤的聚沙形式结构和防沙效果进行了阐述,提出人工聚沙堤是整治该段铁路沙害的一种主要措施。     

广西百色盆地重磁力结合遥感资料在盆地早期评价中的综合研究

本文以百色盆地为例,着重阐述了重磁资料在盆地早期评价中所起的重要作用,提出并总结了重磁资料在盆地早期评价系统中与遥感等资料综合研究的方法系列,指出重磁处理系统是盆地早期评价系统中不可分割的重要部分,遥感图像处理、石油重磁处理系统和地理信息系统(GIS)是进行多元信息综合的强有力的工具。     

Rain induced attenuation studies for V-band satellite communication in tropical region

Satellite communications operating at 10 GHz and above in the tropics suffer severe signal degradation due to rain. Attenuation due to rain at 38 GHz had been measured for a period of 20 months in Malaysia. Analyses carried out include seasonal variations, diurnal effects and the annual cumulative distributions. Obtained results were compared with several established prediction models including the ITU-R. The rain fade characteristics were also investigated in determining the levels of signal loss and fading. In addition, the studies highlight several potential fade mitigation techniques that can be embarked. These fundamental aprehensions are very critical for future earth space communication link design and can be exploited as preliminary groundwork plan for the researchers as well as engineers.     

Optimal filtration and a pulsar time scale

An algorithm is proposed for constructing a group (ensemble) pulsar time based on the application of optimal Wiener filters. This algorithm makes it possible to separate the contributions of variations of the atomic time scale and of the pulsar rotation to barycentric residual deviations of the pulse arrival times. The method is applied to observations of the pulsars PSR B1855+09 and PSR B1937+21, and is used to obtain corrections to UTC relative to the group pulsar time PT_ens. Direct comparison of the terrestial time TT(BIPM06) and the group pulsar time PT_ens shows that they disagree by no more than 0.4 ± 0.17 μs. Based on the fractional instability of the time difference TT(BIPM06)-PT_ens, σ _z = (0.5 ± 2) × 10⁻¹⁵, a new limit for the energy density of the gravitational-wave background is established at the level Ω _g h ² ∼ 10⁻⁹.     

Development and validation of a storm surge forecasting/hindcasting modelling system for the extensive Río de la Plata Estuary and its adjacent Continental Shelf

Natural Hazards - The Río de la Plata (RdP) Estuary is affected by significant surges several times per year. This phenomenon has historically caused catastrophic water-level enlargements of...     

Geomorphology and landscape evolution of bharatpur district, rajasthan

The morphometric analysis of the surface drainage has been carried out for the four micro-watersheds of Bharatpur district, Rajasthan to quantify the drainage morphometry of the district. The morphochronology of landseape evolution has been described. Banaganga represents anomalous drainage, which causes large scale inundation during rainy season. The strain of post-collision Himalayan tectonics resulted in slope mulation in Bharatpur district which changed slope from westerly to easterly. The landform characteristics of Bharatpur district have been arehieved at the National Informatics Center, District Data Base, Bharatpur is alpha numeric mode.     

鱼礁模型对赤点石斑鱼的诱集效果

本文在实验室中水池中观察了赤点石斑鱼在三种不同口径鱼礁模型存在下的行为，结果表明；鱼礁对这种鱼有明显诱集效果，随着模型口径的增大，鱼在礁体放置区分布百分率有增大趋势，而鱼个体平均距离、群体总重心与礁体平均距离和鱼与礁的距离均有减小趋势。可见，口径大小的鱼礁模型有较好的聚鱼效果。