Building a Model of Organizational Activities Experience in Natural Sciences under Stem Education Orientation

STEM educational-oriented Natural Science experience activities are learner-oriented activities Taking learners as the center in all natural science research activities applying engineering technology and mathematics STEM in solving practical problems Based on theoretical research on experiential activities STEM education and the characteristics of Natural Sciences the article studies the educational forces inside and outside the school From there it is proposed to build a model of organizational structure for experiential activities in Natural Sciences oriented toward STEM education The results of this research are meaningful in helping principals see the importance and significance of coordinating educational forces inside and outside the school in organizing experiential activities in Natural Sciences according to orientation STEM education for student

STUDY ON REMOVING COLOR IN THE EXTRACT SOLUTION FROM VEGETABLES FOR ANALYZING ORGANOCHLORIDE PESTICIDES RESIDUE IN HANOI MARKETS

Joint Research on Environmental Science and Technology for the Eart

Review of two genera of freshwater crabs, Larnaudia Bott, 1966 and Neolarnaudia Türkay & Naiyanetr, 1987 (Crustacea: Decapoda: Potamidae) with redescription Neolarnaudiaphymatodes (Kemp, 1923) from Southern Vietnam

ABSTRACT: The occurrence of Larnaudia Bott, 1966 in southern Vietnam remains obscure. Although some previous studies described the presence of Larnaudialarnaudii A. Milne-Edwards, 1869 in Vietnam, our analysis of freshwater crab specimens collected at many locations in southern Vietnam revealed that Neolarnaudia Türkay Naiyanetr, 1987, but not Larnaudia Bott, 1966, is present in southern Vietnam. In this study, we recorded two species of Neolarnaudia, N. phymatodes (Kemp, 1923) and N. botti Türkay Naiyanetr, 1987 in southern Vietnam. Neolaurnaudia phymatodes was poorly knownsince the original description, and is, thus, re-described here. This species can be distinguished from all other Neolarnaudia species by a suite of characters; carapace broader, frontal area with many granules, supraorbital margingranulated, suborbital and pterygostomian regions and merus of third maxillipedcovered with many granules, terminal segment of Gonopod 1 strongly curved inwards and covered with many pubescences, lateral margin of telsonstrongly concaved. Citation: Do Van Tu, Dang Van Dong, Le Van Tho, Phan Doan Dang, 2017. Review of two genera of freshwater crabs, Larnaudia Bott, 1966 and Neolarnaudia Türkay Naiyanetr, 1987 (Crustacea: Decapoda: Potamidae) with redescription Neolarnaudiaphymatodes (Kemp, 1923) from Southern Vietnam. Tap chi Sinh hoc, 39(4): 398-405. DOI: 10.15625/0866-7160/v39n4.8464.*Corresponding author: [email protected], [email protected] 19 September 2017, accepted 12 December 201

SEASONAL VARIATION OF PHYTOPLANKTON FUNCTIONAL GROUPS IN TUYEN LAM RESERVOIR, CENTRAL HIGHLANDS, VIETNAM

Seasonal changes in freshwater phytoplankton assemblages at Tuyen Lam Reservoir in the Central Highlands of Vietnam were classified into 23 functional groups based on physiological, morphological, and ecological characteristics. A total of 168 species were recorded during 10 surveys from 2015 to 2019 at 7 sampling sites, with Chlorophyta dominating in number of species. Phytoplankton abundance varied from 0.18×105 to 21.2×105 cells/L during the study period, mainly due to cyanobacteria. Seven of the 23 functional groups were considered to be dominant (relative density > 5%).  The dominant functional groups were groups M and G in the dry season and groups M, G, P, and E in the rainy season. Group M (Microcystis aeruginosa) was the most common in both seasons, while group P (Closterium, Staurastrum, Aulacoseira), group E (Dinobryon, Synura), and group G (Sphaerocystis, Eudorina) were more common in the rainy season. The Shannon diversity index (H¢) showed that phytoplankton communities were relatively diverse and that most of the study sites were lightly polluted. However, the ecological status has deteriorated at some locations due to the overgrowth of group M, leading to eutrophication in this reservoir. This study highlights the usefulness of functional groups in the study of seasonal changes in phytoplankton dynamics. Functional groups are applied for the first time at Tuyen Lam Reservoir and can be used to predict early-stage cyanobacterial blooms in future studies

Universality in odd-even harmonic generation and application in terahertz waveform sampling

Odd-even harmonics emitted from a laser-target system imprint rich, subtle information characterizing the system's dynamical asymmetry, which is desirable to decipher. In this Letter, we discover a simple universal relation between the odd-even harmonics and the asymmetry of the THz-assisted laser-atomic system -- atoms in a fundamental mid-IR laser pulse combined with a THz laser. First, we demonstrate numerically and then analytically formulize the harmonic even-to-odd ratio as a function of the THz electric field, the source of the system's asymmetry. Notably, we suggest a scaling that makes the obtained rule universal, independent of the parameters of both the fundamental pulse and atomic target. This universality facilitates us to propose a general pump-probe scheme for THz waveform sampling from the even-to-odd ratio, measurable within a conventional compact setup

Blended Learning for Secondary Schools in Nam Dinh Province to Satisfy New Standards: The Current Situation and Proposed Models

We offered blended learning models for high schools in Nam Dinh province to satisfy Vietnam's new criteria. These models were based on general approaches to issues, theoretical research, and field research based on surveys and anket questionnaires conducted throughout the area. The results of a survey demonstrate that high school teachers in Nam Dinh have gained a fundamental grasp of blended learning and have, in practice, embraced both online and face-to-face instruction, particularly during the height of the Covid-19 outbreak. However, there was not a standard model for blended learning, therefore it was only used by a few persons. In other contexts, the concept of "blended learning" referred to what was effectively a face-to-face session that was broadcast over the Internet without the necessary adjustments being made to the content, methodology, or evaluation. As a result, we offer a number of different ways to blended learning for high schools in Nam Dinh in order to improve the quality of education provided throughout the province

Synthesize and characterization of artificial human bone developed by using nanocomposite

The combination of biopolymers with bioceramics plays vital role in development of artificial bone. Hydroxyapatite is extensively used as a material in prosthetic bone repair and replacement. In this paper synthesis of Hydroxyapatite- Polymethyl methacrylate – Zirconia (Hap-PMMA-ZrO2) composite by using powder metallurgy technique. The mechanical, morphological, In-vitro biocompatibility and tribological properties were characterized by universal testing machine, micro-vickers hardness tester, high resolution transmission electron microscope (HR-TEM), MTT assay and pin-on-disc setup. In-vitro cytotoxicity test on HeLa cell lines shows cell viability constant when doses concentration increases so material found non-toxic. Results show that micro Vickers hardness i.e. 520 approximately matches with natural human bone i.e. 400. Compressive strength is less as compared to human bone because of powder metallurgy route used for fabrication and is 74 MPa. Density of proposed composite artificial human bone i.e. 1.52 g/cc is less as compared to natural bone i.e. 2.90 g/cc. The Hap-PMMA-ZrO2 composite will be good biomaterials for bone repair and replacement wor

Phytoplankton diversity and its relation to the physicochemical parameters in main water bodies of Vinh Long province, Vietnam

Phytoplankton samples were collected in 2016 during the dry and rainy seasons at nine sampling sites in Vinh Long province, Vietnam. Some basic environment parameters such as temperature, pH, dissolved oxygen, nitrate and phosphate were measured and a total of 209 phytoplankton species (six phyla, 96 genera) were identified. The phylum that had the greatest number of species was Bacillariophyta (82 species), followed by Chlorophyta (61 species), Cyanophyta (39 species), Euglenophyta (21 species), Chrysophyta (three species) and Dinophyta (three3 species). The phytoplankton density ranged from 4,128 to 123,029 cells/liter. The dominant algae recorded in the study area include Microcystis aeruginosa, Merismopedia glauca, Oscillatoria perornata, Jaaginema sp., Planktothrix agardhii, Coscinodiscus subtilis, Melosira granulata. In particular, Microcystis aeruginosa was the most density dominant species in the total number of sampling sites during the dry season survey, and this species was classified as a group producing toxins harmful to the environment. Surface water quality, according to QCVN 08: 2015/BTNMT was classified into Column A1 for pH, nitrate and Column B1 for dissolved oxygen, and Column B2 for phosphate. Phytoplankton community structure and environmental factors changed substantially between dry and rainy seasons. A Pearson (r) correlation coefficient was used for the relative analysis. The results indicated that the number of phytoplankton species were a significantly positive correlation with pH, dissolved oxygen and nitrate in the rainy season. The phytoplankton abundance was uncorrelated with environmental factors in both seasons.Các mẫu thực vật phù du được thu thập trong năm 2016 (mùa khô và mùa mưa) tại 9 vị trí ở tỉnh Vĩnh Long, Việt Nam. Một số thông số môi trường như nhiệt độ, pH, oxy hòa tan, nitrat và phốt phát được đo ngay tại hiện trường. Tổng cộng 209 loài thực vật phù du được ghi nhận (6 ngành, 96 chi). Số lượng loài cao nhất là tảo Silic (82 loài), kế đến là tảo Lục (61 loài), tảo Lam (39 loài), tảo Mắt (21 loài), tảo Vàng ánh (3 loài) và tảo Giáp (3 loài). Mật độ thực vật phù du dao động từ 4.128 đến 123.029 tế bào/ lít. Các loài ưu thế ghi nhận được ở khu vực nghiên cứu gồm có: Microcystis aeruginosa, Merismopedia glauca, Oscillatoria perornata, Jaaginema sp., Planktothrix agardhii; Coscinodiscus subtilis, Melosira granulata. Trong đó, loài Microcystis aeruginosa chiếm ưu thế nhiều nhất trên tổng số điểm thu mẫu trong đợt khảo sát mùa khô, đồng thời loài này được xếp vào nhóm sản sinh độc tố gây hại cho môi trường. Chất lượng nước mặt theo QCVN 08:2015/BTNMT được xếp vào loại A1 đối với thông số pH, nitrat và loại B1 đối với thông số oxy hòa tan, và loại B2 đối với phốt phát. Cấu trúc quần xã thực vât nổi và các yếu tố môi trường thay đổi đáng kể giữa mùa mưa và mừa khô. Hệ số tương quan Pearson (r) được dùng để phân tích. Kết quả cho thấy số lượng thực vật phù du có tương quan thuận với pH, oxy hòa tan và nitrat trong mùa mưa và có ý nghĩa về mặt thống kê. Mật độ của thực vật phù du không tương quan với các yếu tố môi trường trong cả hai mùa

Some study results of Cam Ranh - Binh Thuan mud eruption strip

Most of the mud eruption locations are distributed in a stretching strip, running in NE-SW direction from Cam Ranh - Ninh Thuan - Binh Thuan NE-SW tectonic fault zone and coinciding with a tectonically crushed zone. The erupted mud consists of sand, mud, clay. The clay contains alkaline montmorillonite, formed following chemical weathering and re-sedimentation processes from rocks containing alkaline minerals in a semi-arid climate area, located in a low terrain or a tectonic subsiding zone with a large fluctuation in groundwater level. The mud eruption  has a close relation to factors (of) climate, topography, geomorphology, hydrogeology, petrography and tectonic activities in the area. 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