Organic Fertilizer Production and Application in Vietnam

Crop production is an important subsector of Vietnam’s agriculture, has an impressive achievement in last 30 years and based on the intensive production with increasing use of chemical fertilizer and pesticide. Consequences are the negative effects on environment and human health and food safety. Organic agriculture has become a trend worldwide and is developing rapidly in the world. In Vietnam the certified organic farming area has expanded since 2012. Organic market revenue in Vietnam is estimated to be at $132.15 million a year. Most Vietnamese certified organic products are exported to international markets. Organic agriculture using organic fertilizer is one of Vietnam government’s priorities. Vietnam already produced organic fertilizer from different materials by using different production technologies, but the production capacity is small and does not meet the demand for organic agriculture. Vietnam government encourages, promotes the organic fertilizer production, application and has the policy to develop the organic fertilizer in Vietnam

Permanence and positive bounded solutions of Kolmogorov predator-prey system

Our main purpose is to present some criteria for the perma- nence and existence of a positive bounded solution of Kolmogorov predator-prey system. Under certain conditions, it is shown that the system is per- manent and there exists a solution which is de_ned on the whole R and whose components are bounded from above and from below by positive constants

Invited review. Bond dissociation enthalpies in benzene derivatives and effect of substituents: an overview of density functional theory (B3LYP) based computational approach

In this review, we have mainly focused on the recent computational studies on the bond dissociation enthalpies (BDE) of the X‒H bonds of the para and meta substituted benzene derivatives (3Y-C6H4X‒H and 4Y-C6H4X‒H with X = O, S, Se, NH, PH, CH2, SiH2 and Y = H, F, Cl, CH3, OCH3, NH2, CF3, CN, NO2). In addition, the remote substituent effects on the BDE(X‒H), the radical stability and parent one have also been discussed in terms of the calculated ground state effect, radical effect and total effect. Model chemistry of ROB3LYP/6-311++G(d,p)//B3LYP/6-311G(d,p) can reproduce the BDE values with the accuracy of 1.0‒2.0 kcal/mol. The good linear correlations between Hammett constants and BDE values were discovered for both para and meta substitutions in phenols, thiophenols, benzeneselenols, anilines and phenylposphines with the R-squared lager than 0.94. In contrast, it does not occur in case of toluenes and phenylsilanes.Keywords. Benzene derivatives, density functional theory, bond dissociation enthalpies, substituent effects, radical effect, ground state effect, total effect, Hammett constants

KHẢ NĂNG ỨC CHẾ ĂN MÒN CỦA AMOXICILLIN TRÊN THÉP CÁC BON TRONG MÔI TRƯỜNG HCl 1 M

The corrosion inhibition of amoxicillin (AMO) on mild carbon steels in 1 M HCl acid solution was studied experimentally and with computational chemistry techniques. The inhibition efficiency increases with the concentration of AMO, reaching the maximal value (84.72%) at 100 mg·L–1 and 25°C. Several quantum chemical parameters were calculated based on the optimal configuration of AMO at the theoretical level of B3LYB/6-31+G(d,p). Molecular dynamics and Monte Carlo simulation were used to configure the most robust absorption configuration on the surface of Fe(110) and clarify the mechanism of the inhitition process. The results show that AMO is an effective corrosion inhibitor.Sự ức chế ăn mòn của amoxicillin (AMO) trên thép các bon nhẹ trong môi trường HCl 1 M đã được nghiên cứu bằng phương pháp thực nghiệm và hóa tính toán. Hiệu quả ức chế ăn mòn của AMO lên thép tăng lên khi tăng nồng độ AMO và đạt cực đại (84,72%) ở 25 °C và nồng độ AMO 100 mg·L–1. Một vài thông số hóa lượng tử được tính toán dựa trên cấu hình tối ưu của AMO ở mức ở mức lý thuyết B3LYP/6-31+G(d,p). Mô phỏng động lực học phân tử và mô phỏng Monte Carlo được ứng dụng để tìm cấu hình                               hấp phụ bền nhất của AMO trên bề mặt Fe(110) và làm rõ cơ chế của quá trình ức chế ăn mòn. Kết quả cho thấy AMO là một chất ức chế ăn mòn hiệu quả đối với thép các bon nhẹ trong dung dịch HCl 1 M

Flexural-strengthening efficiency of cfrp sheets for unbonded post-tensioned concrete T-beams

There has been a limited number of studies about the flexural behavior of unbonded post-tensioned concrete (UPC) beams strengthened with carbon fibre reinforced polymer (CFRP) and these studies have not systematically examined the effect of CFRP sheets on the tendon strain as well as the strengthening efficiency. Moreover, current design guides for the FRP strengthening techniques have not provided any design procedure for UPC structures. This study, thus, investigates the influence of CFRP sheet ratio on the flexural behavior of CFRP-strengthened UPC T-beams and quantifies its effect upon tendon behavior in this kind of UPC beams. The testing program consisted of nine large-scale UPC T-beams strengthened by different layers of CFRP sheets with or without CFRP U-wrapped anchors. The experimental results have shown that the use of CFRP sheets and CFRP U-wrapped anchors significantly affected the tendon strain. The FRP reinforcement ratio governed the flexural capacity, the crack width, the mid-span displacement, and the ductility of the beams in which the strengthening efficiency reduces with the increased number of CFRP layers. The configuration of the CFRP U-wrapped anchors affected the strain of the CFRP sheets, the failure mode and thus the beam behavior. In addition, semi-empirical equations were proposed to estimate the actual strain of unbonded tendons in which the effect of the CFRP sheets and CFRP U-wrapped anchors have been taken into consideration. The proposed equations, which are simple to use, yield reliable predictions with a small variation

Adopting the Hirschman–Herfindahl Index to estimate the financial sustainability of Vietnamese public universities

Over several decades, the Vietnamese government has increasingly cut its investment in the public higher education system and has also introduced a cost-sharing mechanism. Under this scheme, Vietnamese public universities have been seeking other sources of revenue. Despite the bold emphasis on the need for revenue diversification in higher education in Vietnam, there is little empirical evidence of the status quo of Vietnamese public higher education finance. The purpose of this paper was to fill this research gap by using the Hirschman–Herfindahl Index to estimate the degree of financial diversity in 51 public universities in Vietnam between 2015 and 2017. Our findings revealed that all institutions in this study were unsustainable due to their weak financial diversity. Suggestions for policy makers and university leaders that may enhance financial sustainability include the adoption of performance-based financial allocations and the implementation of capacity-building programs for universities with regard to fund-raising and entrepreneurship skills

Primary pulmonary T-cell lymphoma mimicking asthma and community-acquired pneumonia: a rare case report

Primary pulmonary T-cell lymphoma (PPTL) is a rare disease. Diagnosing PPTL is challenging due to non-specific clinical symptoms and imaging. A 32-year-old female presented with persistent fever, cough, and dyspnoea. The symptoms were initially treated as asthma and community-acquired pneumonia without improvement. Chest computed tomography (CT) revealed bilateral consolidations with a CT angiogram sign, and flexible bronchoscopy showed infiltrative lesions causing bronchial stenosis. Histopathological examination of the tissue biopsy identified T-cell lymphoma through immunohistochemical staining positive for CD3. This case highlights the importance of considering differential diagnoses such as PPTL in patients with atypical presentations of asthma or non-resolving pneumonia. This case also demonstrates the diagnostic utility of flexible bronchoscopy in identifying airway obstruction due to malignant cells, which can mimic asthma

A comparison between Hydrochloric acid and Trifluoroacetic acid in hydrolysis method of exopolysaccharide from Ophiocordyceps sinensis in Monosaccharide composition analysis by GC-FID

The monosaccharide composition is one of the crucial factors affecting the bioactivity of exopolysaccharide (EPS) in Cordyceps species. Therefore, many scientists have studied, analyzed monosaccharide composition and structure of EPS from Cordyceps species, especially Ophiocordyceps sinensis (O. sinensis). This study aimed to compare hydrochloric acid (HCl) with trifluoroacetic acid (TFA) in the EPS hydrolysis process in monosaccharide composition analysis by Gas Chromatography with Flame-Ionization Detection (GC-FID). The hydrolysis is a crucial step in forming the acetyl derivative, which helps the GC-FID technique to have good results in monosaccharide composition analysis. The results showed that hydrolysis with HCl gave a higher hydrolysis efficiency and was more suitable than hydrolysis by TFA in pretreatment to EPS for GC-FID. Hydrolysis results were analyzed through thin-layer chromatography and high-performance liquid chromatography (HPLC), then Acetyl derivatives were produced and finally analyzed by GC-FID to determine the monosaccharide composition of EPS. For EPS hydrolyzed by HCl, the analytical results presented that this sample had 6 kinds of monosaccharides, including rhamnose, arabinose, xylose, mannose, glucose, and galactose; the most monosaccharide was glucose. The EPS hydrolyzed by TFA only detected three kinds of monosaccharides, including mannose, arabinose, and galactose, mainly mannose. The study has set a foundation for further analysis of monosaccharide composition and structure of EPS from O. sinensis

Multiple Recurrent Acute Ischemic Strokes Treated by Thrombectomy in a Patient with Acute Pulmonary Embolism

BACKGROUND: Thrombectomy is recommended to treat for an acute ischemic stroke (AIS) patient with anterior large vessel occlusion. However, there were neither detailed guidelines nor systematic reviews of acute ischemic stroke patients having multiple times or re-occluded arteries. CASE REPORT: In our case report, we struggled a multiple (4-times) AIS patient underwent by one intravenous r-tpA and 3 remaining of endovascular treatment of thrombectomy. Especially, the finding of both pulmonary embolism and cerebral arteries occlusion in this patient made us difficult to decide the appropriate treatment plan. The patient was considered having multiple cardiac thrombi pumping out to the brain and pulmonary vessels even in treatment with NOAC (New Oral Anticoagulant). Our priority, normally, was to recanalize the brain vessels compared to the pulmonary arteries. CONCLUSION: In conclusion, based on this noticed case study, we want to share our experiences on the diagnosis of ischemic stroke, the strategy in treatment and prevention with anticoagulant therapy

Confinement mechanism of FRP-confined concrete columns

Strengthening concrete columns by externally wrapping fibre reinforced polymer (FRP) around the perimeter of column sections is rapidly growing. This strengthening technique confines the column cores thus increases their carrying loads and ductility. This thesis is concerned with the confinement mechanism of FRPconfined concrete. Particular attention is given to a new technique for strengthening existing concrete columns. The confinement mechanism of FRP-confined concrete is comprehensively investigated and analysed, which resulted in confinement models for FRP-confined concrete columns. The confinement model for FRP-confined circular concrete columns covers a wide range of unconfined concrete strengths with higher accuracy than other existing models. The confinement model for FRP-confined rectangular concrete columns takes the stress concentration at the corners of sections into account, which has not been done by previous studies. In addition, this study introduces the use of artificial neural network (ANN) to generate analytical equations for calculating the compressive strength and strain of FRP-confined rectangular concrete columns. These equations significantly increase the accuracy compared to existing models. Additionally, the progressive failure mechanism of FRP-confined concrete that has not been previously investigated is experimentally studied. Experimental results show that the maximum usable strain of 1% recommended by ACI 440.2R (2008) and Concrete Society (2012) is un-conservative for FRP-confined concrete. A new model is then proposed to calculate the residual strength of a concrete core at a given axial strain. Finally, a new practical method called circularisation technique is proposed to strengthen existing square reinforced concrete columns. The new technique significantly increases the axial capacity of the existing square columns. Through experimental studies, the proposed technique was verified for not only normal strength concrete but also high strength concrete. Two sets of experimental testing proved the viability of the proposed circularization technique