200 research outputs found

    New records of rare genera of the subfamily Doryctinae (Hymenoptera: Braconidae), with description of five new species from Vietnam

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    Three small genera of the subfamily Doryctinae are newly recorded for the Braconidae fauna of Vietnam, viz. Euscelinus Westwood, 1882; Leptospathius Szépligeti, 1902 and Sonanus Belokobylskij Konishi, 2001. Five new species of these genera are described and illustrated, namely Euscelinus vietnamicus Long, sp. n.; Leptospathius langsoni Long, sp. n.; Leptospathius phamvanluci Long, sp. n.; Leptospathius simulatus Long, sp. n. and Sonanus mocchaui Long, sp. n.. The checklist and distribution of the already known species of three genera are provided. Keys to species of the genera are also given. Keywords: Braconidae, Doryctinae, new record, new species, rare genera, Vietnam.Citation: Khuat Dang Long, Dang Thi Hoa, Nguyen Van Duong, 2017. New records of rare genera of the subfamily Doryctinae (Hymenoptera: Braconidae), with description of five new species from Vietnam. Tap chi Sinh hoc, 39(4): 383-397. DOI: 10.15625/0866-7160/v39n4.10897(*): Corresponding author: [email protected]

    New records of rare genera of the subfamily Cheloninae (Hymenoptera: Braconidae), with description of two new species from Vietnam

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     New species of subgenus Areselonus Braet, 1999 and genus Odontosphaeropyx Cameron, 1910, viz. Chelonus (Areselonus) intermedius Long, sp. n. and Odontosphaeropyx plesius Long, sp. n. (Braconidae: Cheloninae) are described and illustrated. Additionally, these two rare taxa are newly recorded for Vietnam’s braconid fauna. The checklist and distribution of the already known species of the genera are also provided.   

    A Study on Environmental Costs in Coal Mining Production in Vietnam

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    This study is conducted to identify and present environmental costs of mining production in the context of sustainable development (SD) and a lifecycle of coal mining firms. This aim is accompanied by two research questions as (i) What are the environmental costs of mining production in theory and practice in a lifecycle of coal mining firms?; and (ii) What are the key determinants of environmental costs of coal mining production in a lifecycle of coal mining firms? In order to achieve this aim, the process of coal mining production is described from the long-term perspective including projecting, building, operating and liquidation stage of a coal mine. On the basis of process analysis the identification of environmental costs is conducted in a model approach. Environmental costs of mining production are analyzed using international case studies and theoretical and practical assumptions regarding environmental costs management in mining production are formulated. The results show that the environmental costs of mining production are varied in the lifecycle of a coal mine and that they also depend on the geographical location of mining firms. Environmental costs of mining production have to be predicted in a long-term perspective including also post-liquidation costs together with taking into account the sources of their covering and models of financing. Keywords: Coal mining production, mine, lifecycle of a mine, environmental costs. DOI: 10.7176/RJFA/11-18-09 Publication date:September 30th 202

    A Study on Employment for Rural Laborers in the Process of Industrialization and Modernization of Vietnam

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    Employment and job creation are global socio-economic issues and concern every country in the world and Vietnam is no exception. Today, the concept of development is comprehensively understood and economic growth is associated with progress, social justice, poverty reduction, on the basis of creating sustainable jobs for workers. At different times, employments for workers also have different characteristics. In the dimension of this study, employment for rural laborers with the case study of Nam Dinh of Vietnam have been investigated, then some recommendations are proposed for creating more jobs for rural people. Keywords: Employment, job creation, rural employment, rural labor. DOI: 10.7176/EJBM/12-21-13 Publication date:July 31st 202

    Effect of loading paths on hydroforming ability of stepped hollow shaft components from double layer pipes

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    The step hollow shaft components are composed of two layers of different materials, they are formed using tube hydroforming process due to its high strength and rigidity, low weight and flexible profiles, compared to traditional casting, welding, and forming methods. These products are effectively used in industries such as the automotive, shipbuilding, aerospace and defense, and oil and gas sectors. The success of various double layer pipe hydroforming process depends on several factors, with the most important being the internal pressure path and axial loading path. This paper presents research on the effect of input loading paths on the hydroforming ability of a different two-layer metal structure - an outer layer of SUS304 stainless steel and an inner layer of CDA110 copper - using 3D numerical simulations on Abaqus/CAE software. Output criteria were used to evaluate the forming ability of the formed components, including Von Mises stress, Plastic strain component (PEmax), wall thinning, and pipe profile, based on which the input loading paths were combined during the forming process. These output criteria allow for more accurate predictions of material behavior during the hydroforming process, as well as deformation and stress distribution. This can support the design process, improve product quality, reduce errors, and increase production efficiency. The research results can be applied as a basis for optimizing load paths for the next experimental step in the near future, for undergraduate and graduate training, as well as allowing designers and engineers to optimize the process of hydroforming of different 2-layer tubes, reducing costs, improving accuracy, flexible design, minimizing risks, and increasing efficienc

    Analyzing surface EMG signals to determine relationship between jaw imbalance and arm strength loss

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    BACKGROUND: This study investigated the relationship between dental occlusion and arm strength; in particular, the imbalance in the jaw can cause loss in arm strength phenomenon. One of the goals of this study was to record the maximum forces that the subjects can resist against the pull-down force on their hands while biting a spacer of adjustable height on the right or left side of the jaw. Then EMG measurement was used to determine the EMG-Force relationship of the jaw, neck and arms muscles. This gave us useful insights on the arms strength loss due to the biomechanical effects of the imbalance in the jaw mechanism. METHODS: In this study to determine the effects of the imbalance in the jaw to the strength of the arms, we conducted experiments with a pool of 20 healthy subjects of both genders. The subjects were asked to resist a pull down force applied on the contralateral arm while biting on a firm spacer using one side of the jaw. Four different muscles – masseter muscles, deltoid muscles, bicep muscles and trapezoid muscles – were involved. Integrated EMG (iEMG) and Higuchi fractal dimension (HFD) were used to analyze the EMG signals. RESULTS: The results showed that (1) Imbalance in the jaw causes loss of arm strength contra-laterally; (2) The loss is approximately a linear function of the height of the spacers. Moreover, the iEMG showed the intensity of muscle activities decreased when the degrees of jaw imbalance increased (spacer thickness increased). In addition, the tendency of Higuchi fractal dimension decreased for all muscles. CONCLUSIONS: This finding indicates that muscle fatigue and the decrease in muscle contraction level leads to the loss of arm strength

    Some natural heritages of outstanding values for tourism development in Central Highland

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    Tay Nguyen or the Central Highland with the remains of Archean relics is known as the region of the oldest natural formation across Vietnam’s territory. Had been taking place in the Central Highland the combined tectonic activities with typical exogenous process of the Cenozoic. Tay Nguyen contains many valuable natural resources, especially natural heritages that facilitate the development of ecotourism and scientific tourism. Scope of the TN3/T18 national project as part of the Central Highland Program 3 mainly covers research on the outstanding values, including 1) Some areas of extraordinary beauty and aesthetic value such as Dray Nur and Dray Sap waterfalls on the Serepok River in Dak Lak and Dak Nong provinces. 2) Fossil of the yews discovered in the Chu A Thai mountain, Phu Thien district, Gia Lai province; 3) Typical “living fossil plants” of the Central Highland that still exist such as yews (Glyptostrobus pensilis) and two flat-leaf pine-trees (Ducampopinus krempfii) in Gia Lai and Lam Dong; 4) Stone of the Kan Nack series (NA-PP) that is one of the oldest nationwide in basins of the Ba river, Gia Lai province; 5) Spectacular volcano landscape in Gia Lai and Kon Tum; 6) The unique cave system in the Krong No area, formed in basalt layer, is of fundamental difference from Vietnam’s popular limestone caves.ReferencesBonface B. G., Cooper C., 2012: Worldwide Destinations: The Geography of Travel and Tourism, Publishing House Routledge, p.610. Võ Văn Chi. 2004: Từ điển Thực vật thông dụng (Tập 2). Nxb. Khoa học và Kỹ thuật, Hà Nội, 2698tr. La Thế Phúc, Trương Quang Quý, Đỗ Chí Kiên, 2010: Di sản địa chất liên quan đến đá basalt ở Tây Nguyên và các giải pháp bảo tồn phát triển bền vững. Số đặc biệt kỷ niệm 65 năm ngày truyền thống ngành Địa chất Việt Nam. TC Địa chất. Hà Nội, 320, 514-521. La Thế Phúc, Lương Thị Tuất, Trương Quang Quý, 2012: Hang động trong đá basalt ở Cư Jut, Đắk Nông, Việt Nam. Hội nghị Công viên Địa chất Toàn cầu năm 2012 tại Unzen, Nhật Bản, tháng 5/2012. Nguyễn Thành Mến, 2013: Một số đặc điểm quần thể và phân bố loài Thông hai lá dẹt (Pinus krempfii H. Lec) ở Lâm Đồng. Tạp chí Khoa học Lâm nghiệp số 1, năm 2012, tr.2095-2104. Trương Quang Quý, La Thế Phúc, 2010: Trinh Nữ waterfall geologicall heritage, Đắk Nông province. Journal of Geology; series B.35-36/2010; 131-139. Hà Nội: Department of Geology and Minerals of Vietnam. H. Tachihara, TS. T. Honda, 2014: Báo cáo kết quả nghiên cứu sơ bộ các hang động núi lửa ở Đắk Nông, Việt Nam. Hội nghị Thông cáo báo chí “Công bố kết quả khảo sát hang động núi lửa tại khu vực Krông Nô, tỉnh Đắk Nông, Tây Nguyên Việt Nam” ngày 26/12/2014 tại Tổng cục Địa chất và Khoáng sản Việt Nam, số 6 Phạm Ngũ Lão, Hà Nội. Tong Dzuy Thanh, Vu Khuc (Editors), et al., 2006: Stratigraphical units of Vietnam. Vietnam National University Publishing House. Hanoi. 528 pgs. (2012 in lần thứ 2). Trần Văn Trị, Vũ Khúc (Editors) và nnk. 2012: Geology and Earth Resources of Vietnam. Publishing House for Science and Technology, Hanoi. 636 pgs. Wolfgang Eder, 2004: Geoparks - geological attractions: A tool for public education, recreation and sustainable economic development. UNESCO, Division of Earth Sciences, 1, rue Miollis, F-75732 Paris Cedex 15, France.

    Biocompatible chitosan-functionalized upconverting nanocomposites

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    Simultaneous integration of photon emission and biocompatibility into nanoparticles is an interesting strategy to develop applications of advanced optical materials. In this work, we present the synthesis of biocompatible optical nanocomposites from the combination of near-infrared luminescent lanthanide nanoparticles and water-soluble chitosan. NaYF4:Yb,Er upconverting nanocrystal guests and water-soluble chitosan hosts are prepared and integrated together into biofunctional optical composites. The control of aqueous dissolution, gelation, assembly, and drying of NaYF4:Yb,Er nanocolloids and chitosan liquids allowed us to design novel optical structures of spongelike aerogels and beadlike microspheres. Well-defined shape and near-infrared response lead upconverting nanocrystals to serve as photon converters to couple with plasmonic gold (Au) nanoparticles. Biocompatible chitosan-stabilized Au/NaYF4:Yb,Er nanocomposites are prepared to show their potential use in biomedicine as we find them exhibiting a half-maximal effective concentration (EC50) of 0.58 mg mL–1 for chitosan-stabilized Au/NaYF4:Yb,Er nanorods versus 0.24 mg mL–1 for chitosan-stabilized NaYF4:Yb,Er after 24 h. As a result of their low cytotoxicity and upconverting response, these novel materials hold promise to be interesting for biomedicine, analytical sensing, and other applications

    Electronic noses based on metal oxide nanowires: a review

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    Metal oxides are ideal for the fabrication of gas sensors: they are sensitive to many gases while allowing the device to be simple, tiny, and inexpensive. Nonetheless, their lack of selectivity remains a limitation. In order to achieve good selectivity in applications with many possible interfering gases, the sensors are inserted into an electronic nose that combines the signals from nonselective sensors and analyzes them with multivariate statistical algorithms in order to obtain selectivity. This review analyzes the scientific articles published in the last decade regarding electronic noses based on metal oxide nanowires. After a general introduction, Section 2 discusses the issues related to poor intrinsic selectivity. Section 3 briefly reviews the main algorithms that have hitherto been used and the results they can provide. Section 4 classifies the recent literature into fundamental research, agrifood, health, security. In Section 5, the literature is analyzed regarding the metal oxides, the surface decoration nanoparticles, the features that differentiate the sensors in a given array, the application for which the device was developed, the algorithm used, and the type of information obtained. Section 6 concludes by discussing the present state and points out the requirements for their use in real-world applications

    Dairy Value Chain In Vietnam: Evidences from Bavi Area

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    Dairy farming, in Vietnam, existed in the early twentieth century thanks to the favorable natural advantage. During many difficult periods, the Vietnam’s dairy industry has developed constantly and contributed significantly to the food needs ensuring. However, Vietnam’s dairy industry still could not satisfy the domestic milk demand. Retail milk prices in Vietnam are very high, whereas the price of milk sold by the dairy farmers is very low. The cause stems from the control of dairy companies in the quantity and quality of milk. Moreover, that control caused an imbalance in the profits and benefits of each actor in the dairy value chain. This study, hence, finds out the distribution of benefits, costs, value-added among the actors, and problems in the practical management in dairy milk value chain with specific focus on Bavi as the case study
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