ON BOUNDARY VALUE PROBLEMS FOR A CLASS OF SINGULAR INTEGRAL EQUATIONS

Joint Research on Environmental Science and Technology for the Eart

Suggestions for Improving Vietnam Laws on Marine Environment Protection from Contamination Caused by Ship’s Garbage

Due to the fact that Vietnam legal system on marine environmental protection is still inconsistent and deficient, as focusing only on the protection of marine environment either in general or environmental pollution from oil and noxious liquid substances, but lacking a concentration on marine contamination caused by ship’s garbage. It is explained that Vietnam only joined Annexes I and II of International Convention for the Prevention of Pollution from Ships, 1973 as modified by the Protocol of 1978 (hereinafter referred to as the MARPOL 73/78), which serves as a prerequisite condition and fundament of researches and legal system on protection of marine environment. Owing to the lack of in-depth study of the issues, this article is written to describe and analyze the current status of Vietnam laws on the marine environment preservation. Moreover, suggestions for improving the Vietnam legal system on the marine protection from ship’s garbage are suggested in this paper. Keywords: International conventions, improve, Vietnam laws, suggestions, ship’s garbag

Characterization of carboxymethyl cellulase produced by Trichoderma asperellum

Background: The present study characterized extracellular carboxymethyl cellulase (CMCase), an enzyme catalyzes the hydrolysis of the cellulose, from Trichoderma asperellum PQ34 that was isolated from agricultural cultivation soil in Thua Thien Hue, Vietnam.Methods: CMCase was produced by culturing T. asperellum PQ34 on Czapek-Dox medium supplemented with carboxymethyl cellulose (CMC) at 28ºC for 96 h at a shaking speed of 150 rpm. Enzyme activity was spectrophotometerically determined with CMC used as a substrate and the absorbance was measured at 540 nm. The molecular weight of CMCase was determined by zymogram based on sodium dodecyl sulfate-polyacrylamide gel electrophoresis with 0.2% CMC.Results: CMCase achieved the highest activity after 4 days of culture with the optimal pH and temperature at 4 and 55°C. The enzyme maintains pH and thermal stability in the range of 4-5 and 10-40°C and the relative activity of both is more than 90%. The presence of metal ions at 5 mM such as Ca2+, Al3+, or Co2+ increased the enzyme activity up to 133%, 124%, and 217%, respectively. CMCase was stable with 1 mM ethylenediaminetetraacetic acid and 1 M urea, but inhibited by 5% sodium dodecyl sulfate (SDS) and 5% Triton-X100. Zymographic analysis showed that CMCase from T. asperellum PQ34 consists of two enzymes with a molecular weight of about 31 and 66 kDa.Conclusion: CMCases from T. asperellum PQ34 exhibited characteristics of an acidic and thermostable enzyme. The interaction of Co2+ and CMCase resulted in a significant increase in enzyme activity, however they were strongly inhibited by 5% SDS.Keywords: Carboxymethyl cellulase; Cellulase; Endo-β-1,4-glucanase, Trichoderma asperellu

DETERMINING AN APPROPRIATE AGE FOR ESTIMATING SITE INDEX OF Acacia hybrid PLANTATIONS IN SOUTHEASTERN VIETNAM

This article introduces the research results of a site index classification for Acacia hybrid plantations in Dong Nai Province. The objectives of this study were to (i) determine a baseline age of Acacia hybrid plantations to establish their site indices and (ii) develop site index curves for Acacia hybrid plantations. Three standard plots were established for each age group of 1-10 years with 111 trees per plot; 108 trees were measured for the estimation of growth criteria. Three trees were used for tree truncation, and truncated trees did not count for the estimation of tree growth criteria. In this study, the site index (SI) for Acacia hybrid plantations was divided into three levels according to the total height of the dominant trees. The heights collected from 108 trees were used to build the functions of the SI, and three truncated trees were used to examine the possibilities of the functions of SI. Research results showed that the appropriate baseline age of Acacia hybrid plantations at Dong Nai Province is 8 years. The site indices of hybrid plantations were divided into three site levels of I, II, and III, corresponding to heights of 24, 20 and 16 m, respectively. To improve the effectiveness of Acacia hybrid plantation businesses, owners should focus on growing plantations at site index levels of I or II

Marine algal species and their distribution in Phu Quoc marine protected area

This article presents the raw data in relation to the status of, and the distribution of, the 41 marine algal species occurring around and within the An Thoi coral reef strictly protected zone, Phu Quoc Marine Protected Area. The data, which were collected in May 2017, include the detailed description of the locations, the oceanographical conditions, and the photographs of the 41 marine algal species. For more insight, please see “Marine algal species and marine protected area management: A case study in Phu Quoc, Kien Giang, Vietnam” Huynh and Nguyen, 2019

Normal Criteria for Families of Meromorphic Functions

Final version. Title and abstract have been slightly modifiedInternational audienceBy using Nevanlinna theory, we prove some normality criteria for a family of meromorphic functions under a condition on differential polynomials generated by the members of the family