POTENTIAL INTOXICATION BY TOXIC CYANOBACTERIA AND THEIR TOXINS IN SOME VIETNAMESE FRESH WATERBODIES

Joint Research on Environmental Science and Technology for the Eart

Buckling of the initial imperfect rectangular thin plate with variable thickness

This paper analyzes the stability of the rectangular thin plate with sinusoidal changes in the plate thickness combined with initial curvature based on the large deflection theory. The buckling load for simply supported plates is defined using the energy method. The influence of the thickness variation parameter and the initial curvature parameter on the critical loads is investigated

Biohydrogen production by fermentive bacterium Clostridium sp. Tr2 using batch fermenter system controlled pH under dark fermentation

Limitation of fuels reserves and contribution of fossil fuels to the greenhouse effect leads to develop a new, clean and sustainable energy. Among the various options, biohydrogen appears as a promising alternative energy source. The fermentative hydrogen production process holds a great promise for commercial processes. Hydrogen production by fermentative bacteria is a very complex and greatly influenced by pH. This paper presents biohydrogen production by bacterial strain Clostridium sp. Tr2. Operational pH strongly affected its hyrogen production. Its gas production rate as well as obtained gas product were roughly increase twice under controlled pH at 6 than non-controlled condition. Dark fermentation for hydrogen production of strain Tr2 was performed under bottle as well as automatic fermenter scale under optimal nutritional and environmental conditions at 30oC, initial pH at 6.5, then pH was controlled at 6 for bioreactor scale (BioFlo 110). Bioreactor scale was much better for hydrogen production of strain Tr2. Clostridium sp. Tr2 produced 0.74 L hydro (L medium)-1 occupying 72.6 % of total gas under bottle scale while it produced 2.94 L hydro (L medium)-1 occupying 95.82 % of total gas under fermenter scale. Its maximum obtained hydrogen yield of Clostridium sp. Tr2 under bioreactor scale Bioflo 110 in optimal medium with controlled pH 6 was 2.31 mol hydro (mol glucose)-1.Dự trữ nhiên liệu có giới hạn và việc sử dụng nhiên liêu hoá thạch góp phần không nhỏ gây hiệu ứng nhà kính dẫn đến cần phải phát triển năng lượng mới, sạch và bền vững. Trong số các giải pháp, hydro sinh học xuất hiện như một nguồn năng lượng thay thế đầy hứa hẹn. Quá trình lên men sản xuất hydro có tiềm năng lớn để áp dụng trong sản xuất thương mại. Tuy nhiên qúa trình này rất phức tạp và chịu ảnh hưởng lớn bởi pH. Nghiên cứu này trình bày sản xuất hydro sinh học do chủng vi khuẩn Clostridium sp. Tr2. Quá trình sản xuất hydro của chủng này bị ảnh hưởng mạnh mẽ bởi pH thay đổi trong quá trình lên men. Tốc độ tạo khí cũng như lượng khí thu được của chủng này tăng gần gấp đôi trong môi trường có duy trì pH ở pH 6 so với môi trường không kiểm soát pH. Quá trình lên men tối sản xuất hydro của chủng Tr2 được thực hiện ở quy mô bình thí nghiệm cũng như bình lên men tự động trong điều kiện môi trường tối ưu ở 30oC, pH ban đầu 6.5, ở qui mô bình lên men tự động (BioFlo 110), pH môi trường sau đó được duy trì ổn định ở pH 6. Lên men sản xuất hdyro của chủng Tr2 trong bình lên men tự động tốt hơn rất nhiều so với lên men trong bình thí nghiệm. Clostridium sp. Tr2 chỉ tạo ra được 0,74 L hydro (L medium)-1 chiếm 72,6 % tổng thể tích khí thu được ở điều kiện lên men bình thí nghiệm trong khi chủng này sản xuất được 2,94 L hydro (L medium)-1 chiếm 95,82 % tổng thể tích khí ở điều kiện lên men tự động. Sản lượng hydro thu được lớn nhất của chủng này trong bình lên men tự động BioFlo 110 trong trong môi trường tối ưu có kiểm soát pH tại pH 6 là 2,31 mol hydro (mol glucose)-1

SYNTHESIS OF SILVER NANOPARTICLES DOPED IN THE ZEOLITE FRAMEWORK BY CHEMICAL REDUCTION METHOD

ABSTRACT Silver ions (Ag+) were introduced at first into the porous zeolite 4A lattice by an ion-exchange route. And then silver nanoparticles (AgNPs) were synthesized in the zeolite framework by chemical reduction method using hydrazine hydrate (N2H4. H2O) as reducing agent. The synthesized AgNPs/zeolite product was characterized by ultraviolet-visible spectroscopy (UV-vis), X-ray diffraction (XRD), transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDX). The results showed the maximum absorption wavelength (lmax) of AgNPs/zeolite at 427 nm and the average size of the metallic AgNPs doped in the zeolite of about 30 nm. The synthesis process has been considered as suitable one to prepare AgNPs/zeolite with AgNPs content in zeolite of about 1.2% on large scale. The obtained AgNPs/zeolite product has been used for production of porous ceramic water filters with efficiently bacterial disinfection effect for treatment of drinking water

Using of response surface methodology for optimization of biohydrogen production by Clostridium sp. tr2 isolated in Vietnam

Biohydrogen is a clean, renewable, sustainable energy resource due to the highest energy density among all fuels and its combustion has no contribution to the environmental pollution and climate change. Biohydrogen production depends on a number of nutritional and environmental variables. The present paper is to determine the optimum condition for enhanced hydrogen production by a fermentative hydrogen-producing bacterium (designated as Clostridium sp. Tr2) isolated from buffalo-dung in Vietnam. The response surface methodology (RSM) was employed to determine the mutual effects of glucose, yeast extract and iron concentration on its hydrogen production in a batch condition. RSM analysis showed that the highest hydrogen production potential (Ps) was obtained under the condition of 10.18 g L-1 glucose, 2.5 g L-1 yeast extract and 58 mg L-1 FeSO4.7H2O. All three factors had significant influences on the Ps. Glucose and iron concentration, yeast extract and iron concentration were interdependent or there was a significant interaction on Ps. Glucose and yeast extract concentration was slightly interdependent, or their interactive effect on Ps was not significant. Under optimum conditions, the maximum H2 volume of 1080 ml (L medium)-1 were found after 22 h facultative anaerobic fermentation. The experiment results show that the RSM analysis with the central composite design was useful for optimizing the biohydrogen-producing process by newly isolated Clostridium sp. Tr2 in Vietnam

Impact of information and communication technologies on budget transparency of the provincial government in Vietnam

The concept of fiscal transparency holds significant importance; however, its attainment poses considerable challenges. Current discourse suggests that the concept of transparency lacks sophistication. To tackle this hurdle regarding public expenditure, analytical approaches that pertain to the general concept of transparency can be utilized. The present paper aims to ascertain the determinants of the openness of the provincial budget and its subcategories by human development, technology access, as well as industrialization progress, in addition to other relevant indicators. This study aims to ascertain the fundamental principles that underpin the achievement of efficient transparency in public expenditure. In terms of outcomes, the overall model has limited relations to the hypotheses. For the elemental dependent variables, the impact of various forms of transparency on the attainment of public policy goals varies, but generally have similar results. The study has attempted to conclude the components for an optimal transparent budget system, thus providing a suggestion for effective schemes later on

Impact of Education and Network for Avian Influenza H5N1 in Human: Knowledge, Clinical Practice, and Motivation on Medical Providers in Vietnam

BACKGROUND: Knowledge, clinical practice, and professional motivation of medical providers relating to H5N1 infection have an important influence on care for H5N1 patients who require early diagnosis and early medical intervention. METHODS/PRINCIPAL FINDINGS: Novel educational programs including training and workshops for medical providers relating to H5N1 infection in Vietnam were originally created and implemented in 18 provincial hospitals in northern Vietnam between 2008 and 2010. A self-administered, structured questionnaire survey was conducted in 8 provincial hospitals where both educational training and workshops were previously provided. A total of 326 medical providers, including physicians, nurses, and laboratory technicians who attended or did not attend original programs were enrolled in the survey. Knowledge, clinical attitudes and practice (KAP), including motivation surrounding caring for H5N1 patients, were evaluated. The study indicated a high level of knowledge and motivation in all professional groups, with especially high levels in laboratory technicians. Conferences and educational programs were evaluated to be the main scientific information resources for physicians, along with information from colleagues. The chest radiographs and the initiation of antiviral treatment in the absence of RT-PCR result were identified as gaps in education. Factors possibly influencing professional motivation for caring for H5N1 patients included healthcare profession, the hospital where the respondents worked, age group, attendance at original educational programs and at educational programs which were conducted by international health-related organizations. CONCLUSIONS: Educational programs provide high knowledge and motivation for medical providers in Vietnam caring for H5N1 patients. Additional educational programs related to chest radiographs and an initiation of treatment in the absence of RT-PCR are needed. Networking is also necessary for sharing updated scientific information and practical experiences. These enhanced KAPs by educational programs and integrated systems among hospitals should result in appropriate care for H5N1 patients and may reduce morbidity and mortality

Effect of Camellia flava (Pitard) Sealy flower extract on the degeneration of Islets of Langerhans and insulin resistance in alloxan-induced hyperglycemia model on Swiss albino mice

Diabetes has always been a matter of concern to health experts as well as the community due to the increasing number of patients with diabetes and the severe consequences it may cause. Many attempts have been made to discover new treatment options for diabetes, and herbal medicines are currently considered to have great potential. This study was conducted to evaluate the effect of Camellia flava flower extract on the degeneration of the islets of Langerhans and insulin resistance in an alloxan-induced hyperglycemia model in Swiss albino mice. Hyperglycemic conditions were induced by alloxan (55 mg/kg, i.v.). The animals were then treated with glibenclamide (10 mg/kg, p.o.) and flower extract at doses of 1.09 and 2.19 g/kg, p.o. The results showed that the blood glucose, AUC, HbA1c, and HOMA-IR levels of two groups of mice receiving flower extract were considerably lower than those of the hyperglycemic untreated group (p < 0.05). The body weights of these two groups were also lower than the untreated group on the last day of the experiment, though the differences were not significant (p > 0.05). However, this was not observed when assessing insulin levels as well as relative organ weights. In biochemical tests, creatinine and AST and ALT concentrations were evaluated. There was no significant variation in creatinine and AST concentrations between the five experimental groups, whereas mice treated with glibenclamide and flower extract at both doses showed a remarkable decline in ALT concentration (p < 0.05). The hepatic histomicrographs were consistent with ALT results, while the H&E staining of kidneys showed no difference between groups. Histomicrographs of the pancreas revealed that the treatment groups using glibenclamide and flower extract had larger islets of Langerhans than those of the alloxan-treated group. Based on these results, this study demonstrated that Camellia flava flower extract exerted several beneficial effects, including blood sugar level reduction, weight loss promotion, and organ protection, hence making it a new potential herbal medication for the management of diabetes

Surveying of acid-tolerant thermophilic lignocellulolytic fungi in Vietnam reveals surprisingly high genetic diversity

Thermophilic fungi can represent a rich source of industrially relevant enzymes. Here, 105 fungal strains capable of growing at 50 degrees C and pH 2.0 were isolated from compost and decaying plant matter. Maximum growth temperatures of the strains were in the range 50 degrees C to 60 degrees C. Sequencing of the internal transcribed spacer (ITS) regions indicated that 78 fungi belonged to 12 species of Ascomycota and 3 species of Zygomycota, while no fungus of Basidiomycota was detected. The remaining 27 strains could not be reliably assigned to any known species. Phylogenetically, they belonged to the genus Thielavia, but they represented 23 highly divergent genetic groups different from each other and from the closest known species by 12 to 152 nucleotides in the ITS region. Fungal secretomes of all 105 strains produced during growth on untreated rice straw were studied for lignocellulolytic activity at different pH and temperatures. The endoglucanase and xylanase activities differed substantially between the different species and strains, but in general, the enzymes produced by the novel Thielavia spp. strains exhibited both higher thermal stability and tolerance to acidic conditions. The study highlights the vast potential of an untapped diversity of thermophilic fungi in the tropics

A novel high-throughput method for molecular serotyping and serotype-specific quantification of Streptococcus pneumoniae using a nanofluidic real-time PCR system

Serotype-specific quantification data are essential for elucidating the complex epidemiology of Streptococcus pneumoniae and evaluating pneumococcal vaccine efficacy. Various PCR-based assays have been developed to circumvent the drawback of labour-intensive and time-consuming culture-based procedures for serotype determination and quantification of pneumococcus. Here, we applied a nanofluidic real-time PCR system to establish a novel assay. Twenty-nine primer pairs, 13 of which were newly designed, were selected for the assay to cover 50 serotypes including all currently available conjugate and polysaccharide vaccine serotypes. All primer pairs were evaluated for their sensitivity, specificity, efficiency, repeatability, accuracy and reproducibility on the Fluidigm Biomark HD System, a nanofluidic real-time PCR system, by drawing standard curves with a serial dilution of purified DNA. We applied the assay to 52 nasopharyngeal swab samples from patients with pneumonia confirmed by chest X-ray to validate its accuracy. Minimum detection levels of this novel assay using the nanofluidic real-time PCR system were comparable to the conventional PCR-based assays (between 30 and 300 copies per reaction). They were specific to their targets with good repeatability (SD of copy number of 0.1), accuracy (within ±0.1 fold difference in log10 copy number) and reproducibility (SD of copy number of 0.1). When artificially mixed DNA samples consisting of multiple serotypes in various ratios were tested, all the serotypes were detected proportionally, including a minor serotype of one in 1000 copies. In the nasopharyngeal samples, the PCR system detected all the culturepositive samples and 22 out of 23 serotypes identified by the conventional method were matched with PCR results. We conclude that this novel assay, which is able to differentially quantify 29 pneumococcus groups for 45 test samples in a single run, is applicable to the large-scale epidemiological study of pneumococcus. We believe that this assay will facilitate our understanding of the roles of serotype-specific bacterial loads and implications of multiple serotype detections in pneumococcal diseases