Pro-poor intervention strategies in irrigated agriculture in Asia: poverty in irrigated agriculture: issues and options: Vietnam

Irrigated farming / Poverty / Farm income / Irrigation management / Institutions / Legal aspects / Water rates / User charges / Participatory management / Privatization / Participatory rural appraisal / Performance indexes / Irrigation programs / Irrigation systems / Pumping / Irrigation canals / Social aspects / Economic aspects / Rivers / Hydrology / Dams / Households / Income / Regression analysis / Drainage / Cooperatives / Water delivery / Water distribution / Rice / Financing / Drought / Vietnam / Red River Delta / Nam Duong Irrigation System / Nam Thach Han Irrigation System / Han River

Pollen and seed morphology of cleome species (Cleomaceae) in Vietnam

Cleomaceae is a family that includes 18 genera distributed worldwide in tropical and temperate regions. Cleome L. is the largest genus having 207 species, widely distributed in tropical and subtropical regions (POWO 2019). In Vietnam, the genus is represented by four species Cleome rutidosperma DC., C. houtteana Schltdl., C. viscosa L. and C. gynandra L. The present study documents the pollen and seed characteristics of all four species of Cleome in Vietnam, and the data obtained using light microscope and scanning electron microscope are analyzed considering their importance in taxonomic delimitation and understanding their phylogenetic relationship. The results indicated a close relationship between different pollen and aperture types. The striking differences between the pollen shapes among different species of Cleome could be useful in taxonomic and evolutionary studies. Similarly, seed shape and surface characters provided important clues for their delimitation. Based on the pollen and seed morphological characteristics, a taxonomic key has been provided for easy identification of the Cleome species in Vietnam

Effects of Chlorpyrifos Ethyl on Cholinesterase and Growth of Silver Barb (Barbonymus gonionotus)

Chlorpyrifos ethyl is a popular insecticide widely used in agriculture within the Vietnamese Mekong delta, including for rice farming. Here, local farmers often apply pesticides at very high rates which leads to contamination of the surrounding environment. Silver barb (Barbonymus gonionotus) is a fish species indigenous to the delta, which resides in a variety of water bodies and is also commonly cultivated in rice–fish systems. As a result, this species is at high risk of exposure to chlorpyrifos ethyl. This study aims to determine the lethal concentration (LC50) of chlorpyrifos ethyl, as well as the effects of sub-lethal concentrations on the activity of cholinesterase and growth of Silver barb. Lethal concentration testing was conducted in a static non-renewed system. Three concentrations of chlorpyrifos ethyl (1%, 10% and 20% LC50-96 h) were conducted in triplicate to assess the effects of chlorpyrifos ethyl on the brain cholinesterase (ChE) of fingerling fish for 15 days, and on their growth for 60 days. Results showed that chlorpyrifos ethyl was highly toxic to fingerling Silver barb with a LC50-96 h of 0.119 ppm. The lowest observed effect concentration (LOEC) was 1%LC50-96 h for ChE and 10%LC50-96 h for growth. No observed effect concentration (NOEC) of chlorpyrifos ethyl for growth was 1%LC50-96 h. The result from this study suggests that ChE activity is significantly inhibited at environmentally realistic concentrations in the Vietnamese Mekong delta and can be used as a biomarker of pesticide exposure. Further study in the rice fields as well as in the canals or rivers is required

Quelques propriétés physico-chimiques des verres CdGe1-xSb xAs2

Glassy compounds of the system CdGe1-xSbxAs 2 with x varying from 0 to 0.5 have been investigated by means of differential thermal analysis and microhardness measurements. The density and the electrical conductivity have been measured for different compounds. The thermograms show a progressive decrease of the glass transition and crystallization temperatures as the Sb content increases. The microhardness decreases linearly in the composition range 0 ≤ x ≤ 0.3 and tends to be stabilized for higher composition. It is found that the heat capacity measured for two compounds (x = 0, x = 0.5) increases abruptly near the glass transition ; the increase is of less magnitude for compound containing Sb. The crystallization process in different compounds is found to obey approximatively first-order kinetics. The partial substitution of Sb for Ge leads to a strong decrease of the crystallization rate. The enthalpy of crystallization is found to decrease slightly with the increase of Sb content. Optical microscope observations and microhardness measurements on crystallized compounds show the appearance of several phases for samples containing Sb. The chemical composition of these phases has been determined by means of scanning electron microscopy.Des échantillons de verres du système CdGe1-xSbxAs 2 avec 0 ≤ x ≤ 0,5 ont été caractérisés par l'analyse thermique différentielle (A. T. D.) et les mesures de microdureté. La masse spécifique et la conductivité électrique ont été également mesurées pour différentes compositions. Les thermogrammes A. T. D. révèlent une diminution progressive des températures de transition vitreuse et de cristallisation. La microdureté décroît linéairement pour 0 ≤ x ≤ 0,3 et tend à se stabiliser pour des compositions x ≽ 0,3. La chaleur spécifique mesurée pour deux compositions x = 0 et x = 0,5 montre un accroissement brusque au voisinage de la température de transition vitreuse ; l'accroissement est moins élevé pour le composé contenant Sb. Le processus de cristallisation dans les différents composés obéit approximativement à une cinétique du premier ordre. Le remplacement d'une concentration atomique de Ge par une même quantité de Sb conduit à une forte décroissance de la vitesse de cristallisation. L'enthalpie de cristallisation diminue légèrement quand la teneur en Sb augmente. Les observations au microscope optique et les mesures de microdureté sur les échantillons cristallisés révèlent l'apparition de plusieurs phases dans des composés contenant Sb. La composition chimique de ces phases a été déterminée à l'aide de la microscopie électronique à balayage

On inverse problem for a class of fourth order strongly damped wave equations

In this paper, we study the initial inverse problem for a class of fourth order strongly damped linear wave equations. In the beginning, we show that the problem is ill-posed in the sense of Hadamard. Next, we propose the method called: the Fourier truncation method for stabilizing the problem. Convergence estimates are established under a priori regularity assumptions on the problem data

On inverse problem for a class of fourth order strongly damped wave equations

In this paper, we study the initial inverse problem for a class of fourth order strongly damped linear wave equations. In the beginning, we show that the problem is ill-posed in the sense of Hadamard. Next, we propose the method called: the Fourier truncation method for stabilizing the problem. Convergence estimates are established under a priori regularity assumptions on the problem data

Development of Antibacterial, Antioxidant, and UV-Barrier Chitosan Film Incorporated with Piper betle Linn Oil as Active Biodegradable Packaging Material

This study aims to introduce the antibacterial and antioxidant activities of the Piper betle Linn oil (PBLO) into chitosan film (pCS), named as pCS-PBLO film. The morphology, structure, and properties of the pCS-PBLO film, along with the PBLO concentration between 0.4% and 1.2% (v/v), were determined. The film surface became rough and heterogeneous with the addition of PBLO, which directly influenced on mechanical strength of the resultant film. The addition of the PBLO did not affect thermal stability but significant effect on flexibility and mobility of the film. Importantly, the film enhanced the UV-protective property and antioxidant activity as incorporated-PBLO. Moreover, the resulting film revealed the great inhibition efficiency against the negative-gram (E. coli, P. aeruginosa, and S. typhi) and positive-gram (S. aureus) bacteria based on phenolic compounds, such as the acetyleugenol, eugenol, 4-allyl-1,2-diacetoxybenzen, and chavicol acetate in PBLO components. In particular, the pCS-PBLO film may extend the shelf life of king oranges up to two weeks at 25 °C that is longer as compared to the uncoated sample and coated with chitosan alone. These results suggest that the pCS-PBLO film can be used as environmental-friendly and effective food packaging material in the future

Evaporation-induced assembly of colloidal clusters into superclusters with nonconvex deltahedral geometry

Using small colloidal clusters with dumbbell, triplet, tetrahedral, octahedral geometry as elementary building blocks, we investigate the templated-assisted cluster-cluster aggregation into hierarchical clusters, namely superclusters, by means of Monte Carlo simulations. We find that the colloidal superclusters made of dumbbells and triplets produces a unique structural motif that is similar to that of clusters of single colloids, whereas the superclusters composed of tetrahedral and octahedral clusters possess a more complex structure. However, despite their complexity, such structures can be predicted based on a decomposition using triplets as a core and the number of initial “building block” clusters. In particular, a majority of the observable superclusters are members of a particular category of nonconvex deltahedra (Cundy deltahedra). These findings could be useful in preparation of complex colloidal molecules

Effects of Land Quality on Land Use: Farm-level Panel-data Evidence from Viet Nam

The sustainable livelihoods framework (SLF) is a comprehensive way to study agricultural issues. So far, to our best knowledge, no study has applied the SLF to examine the influence of land quality on land use intensively. The current research examines the effects of land quality on farmers’ decision-making on land use in Vietnam by modifying the sustainable livelihoods framework and using the fixed effects regression model. The method controlled the household and commune-level unobserved invariant characteristics and resulted in more robust estimates than pooled Ordinary Least Squares (OLS) estimation. The sample is a five-wave panel dataset of 2008-2016 with 1,534 farm households. The results reveal that land quality affects land-use choices through several aspects of land quality. More specifically, regarding topography, plot fertility level, plot locations, and soil and water conservation, results show that their effects reflect the cultivating practices for each land-use type in the sample. Findings also show that the irrigation system positively affects rice production in Vietnam. Policymakers should consider various aspects of land quality when designing policies and programs relating to land use, irrigation distribution, and especially the master plan for agricultural production and rural development. Flexible guidance for land uses of each type is closely connected with land quality in each region that may be most suitable for sustainable agriculture development