Effects of anthropogenic activities on the heavy metal levels in the clams and sediments in a tropical river

The present study aimed to assess the effects of anthropogenic activities on the heavy metal levels in the Langat River by transplantation of Corbicula javanica. In addition, potential ecological risk indexes (PERI) of heavy metals in the surface sediments of the river were also investigated. The correlation analysis revealed that eight metals (As, Co, Cr, Fe, Mn, Ni, Pb and Zn) in total soft tissue (TST) while five metals (As, Cd, Cr, Fe and Mn) in shell have positively and significantly correlation with respective metal concentration in sediment, indicating the clams is a good biomonitor of the metal levels. Based on clustering patterns, the discharge of dam impoundment, agricultural activities and urban domestic waste were identified as three major contributors of the metals in Pangsun, Semenyih and Dusun Tua, and Kajang, respectively. Various geochemical indexes for a single metal pollutant (geoaccumulation index (I geo), enrichment factors (EF), contamination factor (C f) and ecological risk (Er)) all agreed that Cd, Co, Cr, Cu, Fe, Mn, Ni and Zn are not likely to cause adverse effect to the river ecosystem, but As and Pb could pose a potential ecological risk to the river ecosystem. All indexes (degree of contamination (C d), combined pollution index (CPI) and PERI) showed that overall metal concentrations in the tropical river are still within safe limit. River metal pollution was investigated. Anthropogenic activities were contributors of the metal pollution. Geochemical indexes showed that metals are within the safe limit

Thermal conductivity of PET/(LDPE/Al) composites determined by MDSC

The heat capacity and the thermal conductivity of composites prepared from PET and LDPE containing aluminium particles dispersed in the polyolefin matrix, both obtained from recycled packaging, were measured in the temperature range from 20 to 100 degreesC using modulated DSC. The heat capacity of composites decreases with the increase of PET content and the thermal conductivity showed a very complex dependence on composition, attributed to morphological effects. (C) 2004 Elsevier Ltd. All rights reserved.23663764

Mechanical behaviour and biocompatibility of poly(1-vinyl-2-pyrrolidinone)-gelatin IPN hydrogels

IPN hydrogels based on poly(1-vinyl-2-pyrrolidinone) and gelatin were obtained by casting of aqueous solution using potassium persulphate and glutaraldehyde as respective crosslinking agents. Studies of swelling and mechanical behaviour showed that the samples of different composition can incorporate high content of water and still exhibit high compression strength. The composition has influence at the global crosslinking density what affects the mechanical performance. In vitro biocompatibility and hemocompatibility were also investigated. The materials do not interfere on the cellular functions and neither induce platelet adhesion. From this preliminary evaluation, it is possible to conclude that these hydrogels have potential for applications in the biomedical field. (C) 2002 Elsevier Science Ltd. All rights reserved.2471279128

Composite of low-density polyethylene and aluminum obtained from the recycling of postconsumer aseptic packaging

The recycling process of postconsumer aseptic packaging composed of paper, low-density polyethylene (LDPE), and aluminum consists of recovering paper, the major component, through centrifugation. The remaining mixture of LDPE and aluminum, a recycled composite called PEAL, offers an interesting combination of properties, especially because of the presence of a small amount of poly(ethylene-co-methacrylic acid (EMAA). In this work, this composite is characterized, and the properties are compared with those of pure LDPE and EMAA, the polymers that constitute the recycled material. PEAL is around 15% aluminum particles with different shapes and sizes. The composite presents higher thermooxidative stability, higher crystallinity, lower impact resistance, and higher tensile strength than the other olefin polymers. (c) 2006 Wiley Periodicals, Inc.10153183319

Identification of amino acids in Brazilian propolis

Amino acids of propolis samples from different origins were analysed and quantified. Seven of them presented almost the same percentage in all samples, indicating that bees may have obtained amino acids from three sources: plants, pollen contamination and from their own metabolism. The regeneration properties of propolis in relation to the presence of some amino acids are discussed.5141671111

Transposable elements in Coffea (Gentianales : Rubiacea) transcripts and their role in the origin of protein diversity in flowering plants

Transposable elements are major components of plant genomes and they influence their evolution, acting as recombination hot spots, acquiring specific cell functions or becoming part of protein-coding regions. The latter is the subject of the present analysis. This study is a report on the annotation of transposable elements (TEs) in expressed sequences of Coffea arabica, Coffea canephora and Coffea racemosa, showing the occurrence of 383 ESTs and 142 unigenes with TE fragments in these three Coffea species. Based on selected unigenes, it was possible to suggest 26 putative proteins with TE-cassette insertions, demonstrating a likely contribution to protein variability. The genes for two of those proteins, the fertility restorer (FR) and the pyrophosphate-dependent phosphofructokinase (PPi-PFKs) genes, were selected for evaluating the impact of TE-cassettes on host gene evolution of other plant genomes (Arabidopsis thaliana, Oryza sativa and populus trichocarpa). This survey allowed identifying a FR gene in O. sativa harboring multiple insertions of LTR retrotransposons that originated new exons, which however does not necessarily mean a case of molecular domestication. A possible transduction event of a fragment of the PPi-PFK beta-subunit gene mediated by Helitron ATREPX1 in Arabidopsis thaliana was also highlighted.279438540