Prediction of Load Carrying Capacity of Corroded Reinforced Concrete Beam

A novel method for prediction of the load carrying capacity of a corroded reinforced concrete beam (CRCB) is presented in the paper. Nine reinforced concrete beams, which had been working in an aggressive environment for more than 10 years, were tested in the laboratory. Comprehensive tests, including flexural test, strength test for corroded concrete and rusty rebar, and pullout test for bond strength between concrete and rebar, were condueted. The flexural test results of CRCBs reveal that the distribution of surface cracks on the beams shows a fractal behavior. The relationship between the fractal dimensions and mechanical properties of CRCBs is then studied. A prediction model based on artificial neural network (ANN) is established by the use of the fractal dimension as the corrosion index, together with the basic intbrmation of the beam. The validity of the prediction model is demonstrated through the experimental data, and satisfactory resuits are achieved.     

海底浅层介质切变波的初步研究

初步分析了中国沿海海底浅层介质切变波的传播特性,讨论了多种海底浅层介质切变波与压缩波、物理力学性质之间的关系,并与Hamilton和Chen等人的结果进行了比较。认为海底浅层介质存在切变模量,切变波可以被测量出来,切变波速为50—600m·s-1,测量频率在50—200kHz之间,用波速比可以评价海底浅层介质的应力 应变性质。研究工作有助于描述和评价中国沿海海底浅层介质声学物理性状,并为最终建立中国沿海海底地声模型提供依据。     

In-Situ Observation of Fluid Mud in the North Passage of Yangtze Estuary, China

Observations of fluid mud were made in the lower North Passage of the Yangtze Estuary in February 2000, on 10 -11 August 2000, on 30 - 31 August 2000 (after two strong typhoons), on 21 - 24 August 2000 (neap tide) and on 3 -6 September 2000 (mean tide) respectively. In situ data show that the fluid mud in this area consists of fine cohesive sediment (median size 7.23 μm). The formation and movement of fluid mud varied during the neap-spring and flood-ebb tidal cycle. Observations suggest that fluid mud phenomena in this area may be categorised in a three-fold manner as slack water, storm and saltwedge features. The thickness of the fluid mud layer of slack water during the neap tide ranged from 0.2 to 0.96 m, whereas during the mean tide, the thickness ranged from 0.17 to 0.73 m, and the thickness of the fluid mud layer was larger during slack water than at the flood peak. Shoals cover an area of 800 km^2 with a water depth smaller than 5 m. Erosion of these extensive intertidal mudflats due to storm action provides an abundant sediment source. This is particularly significant in this estuary when the tidal level is lower than 5 m. The lower North Passage is a typical zone of saltwater wedging, so the saltwedge fluid mud has the most extensive spatial range in the estuary.     

耳鲍(Haliotis asinina)核糖体小亚基(18S rRNA)编码基因的克隆与序列分析

采用分子生物学的方法,对南海不同海区的两个地理群体耳鲍(Haliotis asinina)18S rRNA基因全长进行了克隆和序列分析,并将耳鲍18S rRNA基因的序列与NCBI数据库中已收录鲍的18SrRNA基因进行了比较。结果发现,南海耳鲍核糖体18S rRNA基因与耳鲍H.asinina isolate H11核糖体18S rRNA基因序列的相同率高达98%;同一地理群体内耳鲍核糖体18S rRNA基因序列完全一致;不同地理群体间耳鲍核糖体18S rRNA基因在碱基组成上的相似率为99%,仅在某些位点处发生了碱基替换,即腺嘌呤(T)被鸟嘌呤(G)替换;同时,将这两个不同群体中耳鲍的18S rRNA基因与泰国耳鲍18S rRNA基因序列进行比较分析发现,它们之间也只是发生了碱基替换。     

The Spatial Distribution of Caprellidea (Crustacea: Amphipoda): A Stress Bioindicator in Ceuta (North Africa, Gibraltar Area)

Abstract. The caprellid (Crustacea: Amphipoda) community associated with the alga Cystoseira usneoides (L.) Roberts 1967 was studied on a spatial scale in relation to the influence of environmental factors on the coast of Ceuta (North Africa) using multivariate analyses. Twenty-two stations were sampled and five environmental factors were tested (hydrodynamics, silting, suspended organic matter, organic matter in silt and suspended solids). The spatial distribution of the caprellid community reflected the physico-chemical conditions of the coast. Phtisica marina Slabber 1769 was the only species present at the stations of the harbour of Ceuta, characterised by the lowest values of hydrodynamics and the highest values of silting, suspended organic matter and suspended solids. The most exposed stations (high hydrodynamics and low values of silting, dissolved organic matter and suspension solids) were mainly dominated by Caprella danilevskii Czerniavskii 1868 and C. penantis Leach 1814. These two species have developed a "parallel" posture that enables them to attach strongly to the substratum and thus inhabit areas subjected to heavy exposure or strong currents. Caprella acanthifera Leach 1814 and Pseudoprotella phasma (Montagu 1804) preferred stations characterised by moderate values of silting and suspended solids, such as those located in the coastal areas in front of the city of Ceuta, but these species were not found at the most stressed harbour stations.     

Stratigraphy of the sediment infill in Bosphorus Strait: water exchange between the Black and Mediterranean Seas during the last glacial Holocene

The sediment infill over the Paleozoic bedrock in the Bosphorus Strait consists of four sedimentary units which were deposited in the last 26,000 ¹⁴C years B.P. The stratigraphy of these units suggests that this part of the Bosphorus was a freshwater lake between 26,000 and 5,300 ¹⁴C years B.P., depositing sands with a freshwater mollusc fauna of Black Sea neo-euxinian affinity (Dreissena rostriformis, Dreissena polymorpha, and Monodacna pontica). The first appearance of euryhaline Mediterranean molluscs (e.g., Ostrea edulis, Mytilus edulis) was observed at 5,300 ¹⁴C years B.P. in this part of the Bosphorus. Deposition of coarse Mytilus-bank and Ostrea-bank units suggests that the establishment of the present dual-flow regime in the Bosphorus took place at about 4,400 ¹⁴C years B.P.     

环境污染物萘、蒽、菲、芘的好氧微生物降解

多环芳烃（PAHs）是环境污染物，具有致癌性和致突变性。选取香港米埔红树林淤泥富集微生物，研究红树林微生物对PAHs的好氧降解。试验观察到，萘、蒽、菲、芘在液体培养条件下均有较强的挥发性。多底物培养液中的菌群浓度明显高于单底物系统。多次连续转接使培养液中的细菌生长能力增强。初始底物浓度可影响细菌生长速率，底物浓度过低或过高均不利于细菌生长。从分离得到的降解菌中选取豚鼠气单胞菌Aeromonascaviae WⅡ和斑点气单胞菌Aeromonas punctata TⅡ进行单菌降解试验，结果表明，豚鼠气单胞菌WⅡ能够高效降解4种底物，而斑点气单胞菌TⅡ能够高效降解萘、蒽和芘3种底物。另外还发现斑点气单胞菌TⅡ能够明显降低水中菲的挥发速度。     

南四湖湖内浅槽工程施工对水环境的影响及控制措施

南四湖湖内工程是沂沭泗河洪水东调南下续建工程的单项工程,工程区位于山东省省级自然保护区内;挖泥船施工将对湖内水环境产生一定影响。本文从排泥场回水污染物、生产废水和生活污水三个方面阐述了工程施工对水环境的影响程度,并且提出了相应的控制措施。     

The Sponge Population of the Cabrera Archipelago (Balearic Islands): Characteristics, Distribution, and Abundance of the Most Representative Species

Abstract. The abundance, distribution, and species richness of the littoral sponges (0–55 m) from the Cabrera Archipelago (Balearic Islands) were studied along light gradients from the surface to the sea bottom and from cave mouths to their inner parts. A total of 98 species (11 Calcarea and 87 Demospongiae ) were recorded, 8 of which are new records for the Spanish coast.
Cluster and correspondence analyses enabled the identification of a sciophilous sponge group including three subgroups: sponges found only in semi-dark cave habitats, a subgroup common to the coralligenous, precoralligenous, and semi-dark cave biocoenoses, and a third subgroup exclusive to the coralligenous biocoenosis. A small number of photophilic species and other species having a wide bathymetric distribution made up another separate group. No species clusters for the different semi-sciophilous (either fleshy or carbonate) or photophilic seaweed communities were discernible. The number of sponge species was negatively correlated with the irradiance level.     

中国对虾镰刀菌病的细胞病理研究

本文报导中国对虾养成期病原体茄类镰刀菌Fusarium solani(Mart)的细微结构及其引起宿主的细胞病理变化,以便为该病的正确诊断和有效防治提供依据。