Material and monetary flows of construction and demolition waste and assessment on physical and environmental properties of illegally dumped construction and demolition waste in Hanoi.

The main aim of this study is to investigate the material and monetary flows of CDW management and to characterize the distribution of illegally dumped CDW in Hanoi. Construction and demolition waste management has become a source of much concern to the urban authorities and citizens of big cities in Vietnam. It is estimated that 3000 t of CDW were generated per day from construction and demolition activities in Hanoi, but only 45% of the CDW was received at official landfills, while 55% of the CDW was disposed of elsewhere. The consequences of improper waste management are potentially alarming. The study conducted interviews to identify the material and cash flow associated with licensed and unlicensed contractors in CDW classification, transportation, treatment, and disposal, to characterize the distribution of illegally dumped CDW in two districts in Hanoi (urban and suburban districts), and to assess the composition of dumped CDW and environmental assessment of illegally dumped CDW by chemical analyses such as leaching and content tests. The study concluded that illegal dumping was performed mostly by unlicensed private companies. The illegally dumped CDW was mostly composed of mixed materials such as concrete, bricks, stones, and some hazardous materials such as asbestos and gypsum were found. The environmental concern of illegally dumped CDW was mostly dust, blockage of water ways, and inundation of increased suspended solids, whereas the heavy metal leaching concentration of all samples was below the environmental standards in Vietnam.

Development of PEGylated aspartic acid-modified liposome as a bone-targeting carrier for the delivery of paclitaxel and treatment of bone metastasis.

To prevent bone metastasis, we developed polyethylene glycol (PEG)-conjugated aspartic acid (Asp)-modified liposomes (PEG-Asp-Lipo) as a bone-targeting carrier of paclitaxel (PTX) by using Asp-modified 1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine (DPPE-Asp). The affinity of Asp-modified liposomes to hydroxyapatite increased as the concentration of DPPE-Asp increased. The bone accumulation of [3H]-labeled PEG(2)-Asp(33)-Lipo was approximately 24.6% 360 min after intravenous injection in mice, in contrast to 5.4% and 6.7% of [3H]-labeled normal Lipo and PEG(2)-Lipo, respectively. Similarly, [14C]-labeled PTX encapsulated into PEG(2)-Asp(33)-Lipo predominantly accumulated in the bone. Furthermore, using an in situ imaging experiment, we observed that near-infrared fluorescence-labeled PEG(2)-Asp(33)-Lipo selectively accumulated in the bone near the joint after intravenous injection in mice. We also found that FITC-labeled PEG(2)-Asp(33)-Lipo predominantly accumulated on eroded and quiescent bone surfaces. In a bone metastatic tumor mouse model, in which B16-BL6/Luc cells were injected into the left ventricle of female C57BL/6 mice, metastatic bone tumor growth was significantly inhibited by an intravenous injection of PEG(2)-Asp(33)-liposomal PTX. In contrast, PEGylated liposomal PTX hardly affected the growth of metastatic bone tumors. These findings indicate that PEG(2)-Asp(33)-Lipo is a promising bone-targeting carrier for the delivery of PTX and treatment of bone metastasis.

Development of PEGylated carboxylic acid-modified polyamidoamine dendrimers as bone-targeting carriers for the treatment of bone diseases.

In this study, we aimed to develop a polyethylene glycol (PEG)-conjugated third generation polyamidoamine (PAMAM) dendrimer with multiple carboxylic acids as a bone-targeting carrier for the treatment of bone diseases. We conjugated PAMAM backbones to various carboxylic acids [aspartic acid (Asp), glutamic acid (Glu), succinic acid (Suc), or aconitic acid (Aco)] to obtain four different types of carboxylic acid-modified PAMAMs. PEG was covalently bound to carboxylic acid-modified PAMAMs to obtain PEGylated carboxylic acid-modified PAMAMs. In a tissue distribution study, the amount of 111In-labeled unmodified PAMAM taken up by the bone after intravenous injection in mice was 11.3%. In contrast, the dose of 111In-labeled PEG(5)-Asp-PAMAM, PEG(5)-Glu-PAMAM, PEG(5)-Suc-PAMAM, or PEG(5)-Aco-PAMAM that accumulated in the bone after injection was approximately 46.0, 15.6, 22.6, and 24.5%, respectively. The bone clearance rates of 111In-labeled PEGylated carboxylic acid-modified PAMAMs were proportional to their affinities to hydroxyapatite and Ca2+. An intra-bone distribution study showed that fluorescein isothiocyanate-labeled PEG(5)-Asp-PAMAM predominantly accumulated on eroded and quiescent surfaces, a pattern associated with the pathogenesis of bone diseases, such as rheumatoid arthritis and osteoporosis. Our findings indicate that PEG(5)-Asp-PAMAM is a promising drug carrier for efficient drug targeting to the bones.

Characterization of temporal variations in landfill gas components inside an open solid waste dump site in Sri Lanka.

A long-term monitoring of composition of landfill gases in the region with high rainfall was conducted using an argon assay in order to discuss air intrusion into the dump site. Gas samples were taken from vertical gas monitoring pipes installed along transects at two sections (called new and old) of an abandoned waste dump site in Sri Lanka. N2O concentrations varied especially widely, by more than three orders of magnitude (0.046-140 ppmv). The nitrogen/argon ratio of landfill gas was normally higher than that of fresh air, implying that denitrification occurred in the dump site. Argon assays indicate that both N2 and N2O production occurred inside waste and more significantly in the old section. The Ar assay would help for evaluations of N2O emission in developing countries. IMPLICATIONS: A long-term monitoring of composition of landfill gases in the region with high rainfall was conducted using an argon assay in order to discuss air intrusion into the dump site. Argon assays indicate that both N2 and N2O production occurred inside waste and more significantly in the old section.

Emission control for precursors causing acid rain (V): Improvement of acid soil with the bio-briquette combustion ash.

The bio-briquette technique which mixes coal, biomass and sulfur fixation agent and bio-briquettes under 3-5 t/cm2 line pressure has aroused people's attention in view of controlling the air pollution and the acid rain. In this paper, the physicochemical properties of bio-briquette and its ash were investigated. And the acid soil was improved by the bio-briquette combustion ash, which contained nutritive substances such as P, N, K and had the acid-neutralizing capacity (ANC). The pH, EC, effective nutrient elements (Ca, Mg, K, P and N), heavy metal elements (Al, Cu, Cd, Cr, Zn and Mn) and acid-neutralizing capacity change of ash-added soils within the range of 0-10%, were also studied. Specially, when 5% bio-briquette combustion ash was added to the tested soil, the content of the effective elements such as Ca, Mg and K rose by 100 times, 7 times and twice, respectively. The total nitrogen also increased by about twice. The results showed the oxyanions such as that of Al, Cu, Cd, Cr, Zn and Mn were not potentially dangerous, because they were about the same as the averages of them in Chinese soil. It is shown that the ANC became stronger, though the ANC hardly increases in the ash-added soil. On the basis of the evaluation indices, it is concluded that the best mixture ratio is to add 2.5%-8% of the bio-briquette combustion ash to the tested soil.