THE FATE OF DISCHARGED POLYCYCLIC AROMATIC HYDROCARBONS (PAHs) IN WATER STREAMS

Polycyclic aromatic hydrocarbons (PAHs), also known as polynuclear aromatic hydrocarbons, are potent atmospheric pollutants consisting of fused aromatic rings and do not carry or contain heteroatoms/substituents. 16 of PAHs have been classified by Environmental Protection Agency (EPA) for possible carcinogenic properties. It is discovered that PAHs are found abundant in water stream. Most of the PAHs are discharged without getting treated properly at sewage treatment plant. When exposed to the environment, the PAHs will be degraded either in microbial degradation or photo degradation pathway. The PAHs will be then transformed to various metabolites, creating ‘daughters’ and byproducts along its degradation. They may also be mutagenic or carcinogenic even if their parent compounds are not (International Association of Oil and Gas Producers, 2005). A research study was conducted on former works on PAHs and its metabolites. This included the current study to identify various sources of PAHs in water stream in river of Sungai Perak near the area Teluk Kepayang. Samples were obtained from influent of water treatment plant (WTP) in Teluk Kepayang and were analysed with Gas Chromatography/Mass Spectrometry (GC/MS) to formulate conversion path of carcinogenic PAHs. Tests were performed as well on influent and effluent of Universiti Teknologi PETRONAS (UTP) sewage treatment plant (STP) for studies on sewage polluted urban streams. The samples were then used as test solution for guppy (Poecilia reticulate) as their living environment to establish toxicity intensity of carcinogenic PAHs parents and daughter products through 96hours acute toxicity test. GC/MS analysis identified phthalic acid and benzoic acid as major derivatives found in all samples. The analysis showed the detection of Naphthalene and few other suspected derivatives in influent WTP Teluk Kepayang sample. Mortality rate of Poecilia reticulate against time exposure of 96 hours was 20% for influent Teluk Kepayang WTP and 10% for influent UTP STP whereas the rate is 0% for effluent UTP STP. It was observed that the amount of PAHs and its derivatives detected in both effluent and influent of UTP STP and influent of Teluk Kepayang WTP are not harmful to the environment

THE FATE OF DISCHARGED POLYCYCLIC AROMATIC HYDROCARBONS (PAHs) IN WATER STREAMS

Polycyclic aromatic hydrocarbons (PAHs), also known as polynuclear aromatic hydrocarbons, are potent atmospheric pollutants consisting of fused aromatic rings and do not carry or contain heteroatoms/substituents. 16 of PAHs have been classified by Environmental Protection Agency (EPA) for possible carcinogenic properties. It is discovered that PAHs are found abundant in water stream. Most of the PAHs are discharged without getting treated properly at sewage treatment plant. When exposed to the environment, the PAHs will be degraded either in microbial degradation or photo degradation pathway. The PAHs will be then transformed to various metabolites, creating ‘daughters’ and byproducts along its degradation. They may also be mutagenic or carcinogenic even if their parent compounds are not (International Association of Oil and Gas Producers, 2005). A research study was conducted on former works on PAHs and its metabolites. This included the current study to identify various sources of PAHs in water stream in river of Sungai Perak near the area Teluk Kepayang. Samples were obtained from influent of water treatment plant (WTP) in Teluk Kepayang and were analysed with Gas Chromatography/Mass Spectrometry (GC/MS) to formulate conversion path of carcinogenic PAHs. Tests were performed as well on influent and effluent of Universiti Teknologi PETRONAS (UTP) sewage treatment plant (STP) for studies on sewage polluted urban streams. The samples were then used as test solution for guppy (Poecilia reticulate) as their living environment to establish toxicity intensity of carcinogenic PAHs parents and daughter products through 96hours acute toxicity test. GC/MS analysis identified phthalic acid and benzoic acid as major derivatives found in all samples. The analysis showed the detection of Naphthalene and few other suspected derivatives in influent WTP Teluk Kepayang sample. Mortality rate of Poecilia reticulate against time exposure of 96 hours was 20% for influent Teluk Kepayang WTP and 10% for influent UTP STP whereas the rate is 0% for effluent UTP STP. It was observed that the amount of PAHs and its derivatives detected in both effluent and influent of UTP STP and influent of Teluk Kepayang WTP are not harmful to the environment

Biological thiols-triggered hydrogen sulfide releasing microfibers for tissue engineering applications

By electrospinning of polycaprolactone (PCL) solutions containing N-(benzoylthio)benzamide (NSHD1), a H(2)S donor, fibrous scaffolds with hydrogen sulfide (H(2)S) releasing capability (H(2)S-fibers) are fabricated. The resultant microfibers are capable of releasing H(2)S upon immersion in aqueous solution containing biological thiols under physiological conditions. The H(2)S release peaks of H(2)S-fibers appeared at 2~4 hours, while the peak of donor alone showed at 45 minutes. H(2)S release half-lives of H(2)S-fibers were 10–20 times longer than that of donor alone. Furthermore, H(2)S-fibers can protect cells from H(2)O(2) induced oxidative damage by significantly decreasing the production of intracellular reactive oxygen species (ROS). Finally, we investigated the H(2)S-fibers application as a wound dressing in vitro. Given that H(2)S has a broad range of physiological functions, H(2)S-fibers hold great potential for various biomedical applications

An insight of S-nitrosylation of human GIF

Neural growth inhibitory factor (GIF), a member of metallothionein family (metallothionein-3, MT3), was well known by its distinct neural growth inhibitory activity, which is not shown by other MT isoforms. However, till now, people still did not know clearly how GIF exerts its biological functions. Since it has been reported that GIF might serve as NO scavenger and was related to the release of zinc, our study was focused on the interaction of GIF and NO. By studying the reactions of human GIF and human MT1g with SNOC - a type of NO donor, it was found that GIF was more reactive than MT-1g toward SNOC. In order to further figure out if the high reactivity of GIF in this reaction resulted from the acid-base catalysis, several mutants were constructed: E23K, E41G/E43A, E23K/E41G/E43A. By studying their basic properties and the reactions toward SNOC, it was found that the S-nitrosylation of GIF was not only related to the acid-base catalysis, but also to the accessibility of metal-thiolate clusters. © 2005 SIOC, CAS, & Wiley-VCH Verlag GmbH & Co. KGaA.link_to_subscribed_fulltex