Vietnam Journal of Science, Technology and Engineering

6-9

Authors: Anh Tuan Pham

Vietnam has spent a considerable amount of money to install a satellite exploration program. This article presents the most important achievements of the implementation of this program in Vietnam and gives recommendations for supportive policies that will allow for the development of space exploration in the future.

14-17

Authors: Van Nghia Tran

This paper presents the implementation of RGB↔YCbCr color space conversion circuits (IP-cores) necessary for many video designs. These IP-cores offer simplified 3x3 matrix multipliers used to convert three input color samples (RGB or YCbCr) to three output samples (YCbCr or RGB). The optimized structure of IP-cores uses only four multipliers (or XtremeDSP slices) to implement the RGB↔YCbCr transformation by taking advantage of the dependencies between coefficients in the conversion matrix. Parameterizable IP-cores are used to confirm compliance to multi-standards and optimize hardware implementation. IP-cores have been verified successfully using xilinx vivado system generator 2016.2 for visually inspected output results and for verification against known models in the MATLAB/Simulink software environment.

27-31

Authors: Anh Thu Quang, Cong Thanh Vo

In order to detect some of the determinants of rice flavor, an experiment was carried out that studied panicle primordia at the initial panicles of three aromatic varieties: Nang Thom Cho Dao mutation (NTCDm), Thom Bay Nui (TBN), and Jasmine-85, and IR28 was used as the control variety (non-aroma). The samples were dyed from the primordium stage to the ripe-pollen stage. Results showed that there were two key differences between the aromatic rices and the control. The first point of difference was at the primordium stage, and the second was after, as a consideration of the number of bivalents (pairs of homologous chromosomes). As for the three aromatic rice varieties, there appeared a lobe division at the branch primordium; at the diplotene stage of meiosis, and seven to eight stained bivalents appeared while the control had no lobe division and the number of stained bivalents achieved 11 to 12

36-42

Authors: Dinh Kha Le, Huy Thinh Ha

“Acacia hybrids” refers to the inter-specific hybrids of A. mangium and A. auriculiformis, including natural, artificial and polyploid ones. The superiorities of selected acacia hybrid are fast growth, straight stem form, small branches, high productivity, and high ratio of wood utilisation. Acacia hybrids are recognized as having a higher pulping potential and greater soil improvement ability than that of the parental species, which may be shown to have 2.5-13 times larger numbers of nitrogen - fixing nodules on its roots in nursery stage. Mass propagation technology using both cutting and tissue culture has been successfully developed for acacia hybrid, enabling large-scale clonal forestry to improve plantation productivity and quality. The area of acacia hybrid plantations up to 2016 was estimated to be 500,000 ha, with an annual increase of 30,000-35,000 ha, making it the most widely planted forest tree variety in Vietnam. Acacia hybrids and propagation technologies have also been introduced in Malaysia, Indonesia, Thailand, Laos, and Cambodia. The research and development of acacia hybrid breeding can be considered as a revolution in the forestry sector and has created new and advanced approaches for both research and training in tree breeding in Vietnam.

49-53

Authors: Ngoc Ha Le, Hong Son Mai, Van Nguyen Le, Quang Bieu Bui

Objective: To assess metabolic tumor response using 18F-FDG PET/CT scan in early stage non-small cell lung cancer (NSCLC) treated by CyberKnife radiosurgery. Materials and Methods: 30 patients were diagnosed proven by biopsy and inoperable stage I NSCLC, and were enrolled into this study. 18F-FDG PET/CT was performed prior to the program, and at three months following the radiosurgery treatment. The tumor maximum standardized uptake value (SUVmax) was recorded for each time point and the PERCIST criteria was applied to assess tumor response. Results: 30 patients with NSCLC, stage me after CyberKnife radiosurgery was followed-up after 12 months. The 1-year Kaplan-Meier local control estimate was 96.7%, the cut-off of SUVmax was 10, and revealed the local tumor control to have a statistically significant difference. Mean tumor SUVmax before treatment was 10.5±3.25 (range, 5.0 to 20). During early follow-up the mean SUVmax in the tumor remained high due to peritumoral radiation-induced pneumonitis visible on CT imaging. After radiosurgery for six months, 18F-FDG PET/CT images showed that 21 of 30 patients (70%) had a partial metabolic response, 8 of 30 patients (26.7%) had stabilized diseases, and one patient (0.3%) had disease progression. Meanwhile, CT could not reveal the progressed patient. Conclusions: Local control following CyberKnife radiosurgery for stage I NSCLC is acceptable. Transient increases in tumor SUVmax are likely related to radiation-induced pneumonitis. The value of 18F-FDG PET/CT imaging for early metabolic tumor response after stereotactic body radiation therapy (SBRT) could be higher than anatomic response on CT.

58-72

Authors: Van Hieu Nguyen

During the present decade application-oriented basic research on nanomedicine has rapidly developed in Vietnam. This work is a review of this development. It was directed towards following scientific topics: Biomedical utilization of PLA-TPGS and PLA-PEG, dendrimer-based anticancer drugs, special drug delivery nanosystems, various utilizations of nanocurcumin in nanomedicine, biomedical application of hydrogel nanocomposites, biosensors and biosensing methods, toxicity and antibacterial activity of different types of nanoparticles. Obtained scientific results demonstrated that although Vietnamese application-oriented basic research on nanomedicine began to develop only in this decade, it has achieved very promising successes.

79-87

Authors: Van Thang Nguyen, Van Khiem Mai, Van Thang Vu, Dang Mau Nguyen, Ngoc Bich Phuong Nguyen, Duy Diep Le, Truong Minh Ha, Nhat Linh Luu

This study represents the observed and projected changes in climate extremes in the context of climate change. A linear regression method was used to identify trends and variations of climate extremes in the past, while projected changes in climate extremes were detected based on dynamical downscaling and compared with the baseline period (1986-2005). The results show that daily maximum and minimum surface air temperatures (Txx, Tnn) increased considerably with the highest value of about 0.9oC/decade during the period of 1961-2014. The number of hot days increased across most observed stations, especially in Central Vietnam. Trends of extreme precipitation varied among the regions: decreasing across most stations in the Northwest, Northeast and Red River Delta; and increasing at other stations. In Vietnam, over the period 1959-2015, there were no obvious changes in the frequency of tropical cyclones causing landfall events, including typhoons and tropical depressions. However, the rate of occurrence of the very strongest typhoons are currently on the increase. In recent years, typhoon seasons tend to end later than in the past, and typhoons occur more frequently in Southern regions. Predicted results of climate extremes in the future for the periods 2046-2065 and 2080-2099, compared with the baseline period of 1986-2005 under the medium and high scenario (RCP 4.5 and RCP 8.5) show that temperature extremes will likely increase considerably in the future. The number of hot days will likely increase in both frequency and intensity, while the number of extreme cold days will likely decrease at most stations in the North. A maximum 1-day rainfall will also likely increase across all regions in Vietnam. Results from models show that the number of strong typhoons will likely increase in the mid- and late-century.

93-96

Authors: Ngoc Anh Nguyen

During the dry season of 2015-2016, the Mekong Delta had suffered the worst historic drought and salinity intrusion occurrence on record, causing heavy damages to nine coastal provinces (in total 13 provinces) of the Mekong River Delta. Just after the drought and salinity intrusion occurred, the media offered some different opinions suggesting possible solution which offer effective responses and stable development to coastal regions. The author suggests that in order to have sustainable development for the Mekong Delta in general and for the coastal zones in particular, Vietnam needs to have some basic short-term and long-term solutions, for each region as well as the whole delta, including drought-salinity intrusion and flooding programs, structural and non-structural works, and coverage for both the Mekong Delta and the whole Mekong River Basin.