Oligochitosans (OCT) were prepared from chitosan (CTS) by gamma irradiationtechnique. The parameters affecting to the chitosan degradation were studied. And then, OCT nanoparticles wereformed using the method of tripolyphosphate (TPP) cross-linking. Effect of concentration and molecular weight of OCT, concentration of TPP on particle size of the formed OCT nanoparticles were also studied. The formation of OCT nanoparticles was verified by Fourier transform infrared (FT-IR) spectrometer and differential scanning calorimeter (DSC), the morphology was observed using scanning electron microscope (SEM), and the characteristics (particle size and zeta potential) of OCT nanoparticles were also studied. The effect of OCT nanoparticles on strawberry presevation was carried out using the coating method. Results showed that an increase in radiation dose resulted in a decrease of chitosan molecular weight. The OCT with molecular weight of approximately 7.7 kDa was obtained by the synergistic effect of hydrogen peroxide (5 %, v/v) and gamma ray at dose of 30 kGy. The smaller OCT nanoparticles was obtained with a lower molecular weight of OCT. The results of FTIR, DSC indicated the success in the formation of OCT nanoparticles with the particle size approximately 129.9 nm, with the spherical shape. The application of OCT nanoparticles on strawberry has prolonged the preservation times approximately 2.5 times higher comp
Copolymer hydrogel (PVA-g-AA) having varied PVA (Polyvinyl alcohol) and AA (Acrylic acid) content is prepared by gamma induced radiation polymerization. The parameters affecting the gel fraction yield have been studied. The gel fraction and the swelling property are found to be 92.39 and 905% respectively at an absorbed dose of 20 kGy. Structural and property characteristics were determined by Fourier Transform Infrared (FTIR) spectrometer and Differential Scanning Calorimetry (DSC). The surface morphology of PVA and copolymer has been studied with Scanning Electron Microscope (SEM). The factors affecting the metal uptake such as pH, time, and initial feed metal concentration were investigated. It is found that at pH 5 and after 240 minutes the maximum adsorption amount are 178, 161, 117, and 110 mg/g for Pb2+, Zn2+, Co2+, and Ni2+ respectively.
Background: The Nested IS6110 PCR is used for detecting tuberculosis, however IS6110 sequence is not present in the genome of all strains of M.tuberculosis, the result may be false negative. The gene coding 16S ribosome always contains a short sequence specific to M. tuberculosis complex. Objects: Performance of the 16S Real-time PCR to detect M. tuberculosis and combining to the nested IS6110 PCR to determine the rate of Mtb strains without IS6110 from clinical samples. Materials and method: Performance of 16S rDNA PCR by commercial kit of Viet A Inc. for all 480 samples, the samples which were positive with the 16S rDNA PCR were retested in IS6110 PCR assay by in-house kit. Results: The Realtime 16S rDNA PCR detected 258 cases (53.8%) of tuberculosis. There were 3 (1.2 %) M. tuberculosis strains which do not harbor IS6110 sequence in genome. Conclusion: The IS6110 nested PCR can be applied more widely than the 16S rDNA realtime PCR. In case of using IS6110 PCR assay, results may show a low proportion of false negative. Combining 16S rDNA PCR with the IS6110 based PCR allowed detection of deletion of IS6110 sequence in M. tuberculosis isolates.
Urbanization is an objective law of socioeconomic development. However, the drainage system is incompatible with the development of urban areas and the increasing population. Some sewer lines are built or added, but they are not synchronized and poorly sloped with debris and inadequate cross-sectional areas, leading to local flooding. In this study, we applied and locally optimized the Mike Urban model to the sewer network in Da Nang City to evaluate the inundation capability as well as the current and future sewer system capacity. The model was calibrated and validated at three typical sites for the data on October 16 and November 7, 2011; evaluated for the heavy rain data on October 14, 2022; and tested scenarios for 2030. The results showed that during heavy rain on October 14, 2022, many urban areas of Da Nang City were crowded, and the number of flooded manholes along the river suddenly increased dramatically because of the high water level and low ground level, which was impossible for rainwater to flow into the river during the high tide. The study also revealed that the planning for the drainage system until 2030 has improved the water drainage situation in the city by adjusting and adding some drainage systems. While this region remains poorly studied, this study brings original information that will help stakeholders to adopt appropriate strategies for the management of their cities that experience critical inundation.
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