A Kluyveromyces marxianus 2-deoxyglucose-resistant mutant with enhanced activity of xylose utilization

Thermotolerant ethanologenic yeast Kluyveromyces marxianus is capable of fermenting various sugars including xylose but glucose represses to hamper the utilization of other sugars. To acquire glucose repression-defective strains, 33 isolates as 2-deoxyglucose (2-DOG)-resistant mutants were acquired from about 100 colonies grown on plates containing 2-DOG, which were derived from an efficient strain DMKU 3-1042. According to the characteristics of sugar consumption abilities and cell growth and ethanol accumulation along with cultivation time, they were classified into three groups. The first group (3 isolates) utilized glucose and xylose in similar patterns along with cultivation to those of the parental strain, presumably due to reduction of the uptake of 2-DOG or enhancement of its export. The second group (29 isolates) showed greatly delayed utilization of glucose, presumably by reduction of the uptake or initial catabolism of glucose. The last group, only one isolate, showed enhanced utilization ability of xylose in the presence of glucose. Further analysis revealed that the isolate had a single nucleotide mutation to cause amino acid substitution (G270S) in RAG5 encoding hexokinase and exhibited very low activity of the enzyme. The possible mechanism of defectiveness of glucose repression in the mutant is discussed in this paper
http://repository.vnu.edu.vn/handle/VNU_123/33833

Anti-MRSA-acting carbamidocyclophanes H-L from the Vietnamese cyanobacterium Nostoc sp. CAVN2

The methanol extract of the Vietnamese freshwater cyanobacterium Nostoc sp. CAVN2 exhibited cytotoxic effects against MCF-7 and 5637 cancer cell lines as well as against nontumorigenic FL and HaCaT cells and was active against methicillin-resistant Staphylococcus aureus (MRSA) and Streptococcus pneumoniae. High-resolution mass spectrometric analysis indicated the presence of over 60 putative cyclophane-like compounds in an antimicrobially active methanol extract fraction. A paracyclophanes-focusing extraction and separation methodology led to the isolation of 5 new carbamidocyclophanes (1-5) and 11 known paracyclophanes (6-16). The structures and their stereochemical configurations were elucidated by a combination of spectrometric and spectroscopic methods including HRMS, 1D and 2D NMR analyses and detailed comparative CD analysis. The newly described monocarbamoylated [7.7] paracyclophanes (1, 2, 4 and 5) differ by a varying degree of chlorination in the side chains. Carbamidocyclophane J (3) is the very first reported carbamidocyclophane bearing a single halogenation in both butyl residues. Based on previous studies a detailed phylogenetic examination of cyclophane-producing cyanobacteria was carried out. The biological evaluation of 1-16 against various clinical pathogens highlighted a remarkable antimicrobial activity against MRSA with MICs of 0.1-1.0 μM, and indicated that the level of antibacterial activity is related to the presence of carbamoyl moieties.
http://repository.vnu.edu.vn/handle/VNU_123/33834

A tool for assessing quality of rescue plans by combining visualizations of different business process perspectives

Rescue plans for crisis situations such as natural or made disasters are mostly presented in a textual format to the relevant authority. Assessing the quality of a rescue plan requires analyzing different perspectives, such as plan complexity, resources costs, service time, allocation strategy and organization efficiency. Unfortunately, textual rescue plans lack a formal structure to ease the reading and navigation through the document. To address this problem we are composing tailored visualizations, each visualization representing a particular perspective. We provide a domain specific language to describe domain specific visualizations of processes. We validate our approach using static and dynamic analysis of the Ho Chi Minh city rescue plan in case of a tsunami. Our approach provides recommendations that are useful for the authority to improve the original rescue plan.
http://repository.vnu.edu.vn/handle/VNU_123/33835

Research and Application of Remote Sensing and GIS Technologies in Determining and Forecasting Land Use Changes by Markov Chain in y Yen District-Nam Dinh Province

The land's natural resources are invaluable and a requisite for the existence and development of humans and other organisms on Earth. In recent years, under the strong impact of new directions in economic and social development, the demand for land has been increasing. The percentage of land used for residential living, transportation, irrigation and infrastructure tends to increase, while the share of agricultural land is continuously decreasing. Consequently, the allocation and efficient use of land is one of the most important concerns in order to enable sustainable development, environmental protection and ecology. Therefore, research to determine the volatility and changing trends in land use is necessary. This study uses remote sensing and GIS technology, combined with the Markov Chain to determine variation and forecast the changes in land use in the Y Yen district of the Nam Dinh province of Vietnam. This will create a basis for helping land managers grasp the situation in local land use management.
http://repository.vnu.edu.vn/handle/VNU_123/33840

Research Update Enhanced energy storage density and energy efficiency of epitaxial Pb0.9La0.1(Zr0.52Ti0.48)O3 relaxor-ferroelectric thin-films deposited on silicon by pulsed laser deposition

Pb0.9La0.1(Zr0.52Ti0.48)O3 (PLZT) relaxor-ferroelectric thin films were grown on SrRuO3/SrTiO3/Si substrates by pulsed laser deposition. A large recoverable storage density (Ureco) of 13.7 J/cm3 together with a high energy efficiency (η) of 88.2% under an applied electric field of 1000 kV/cm and at 1 kHz frequency was obtained in 300-nm-thick epitaxial PLZT thin films. These high values are due to the slim and asymmetric hysteresis loop when compared to the values in the reference undoped epitaxial lead zirconate titanate Pb(Zr0.52Ti0.48)O3 ferroelectric thin films (Ureco = 9.2 J/cm3 and η = 56.4%) which have a high remanent polarization and a small shift in the hysteresis loop, under the same electric field.
http://repository.vnu.edu.vn/handle/VNU_123/33841

Enhanced cellular uptake and cytotoxicity of folate decorated doxorubicin loaded PLA-TPGS nanoparticles

Doxorubicin (DOX) is one of the most effective anticancer drugs for treating many types of cancer. However, the clinical applications of DOX were hindered because of serious side-effects resulting from the unselective delivery to cancer cell including congestive heart failure, chronic cardiomyopathy and drug resistance. Recently, it has been demonstrated that loading anti-cancer drugs onto drug delivery nanosystems helps to maximize therapeutic efficiency and minimize unwanted side-effects via passive and active targeting mechanisms. In this study we prepared folate decorated DOX loaded PLA-TPGS nanoparticles with the aim of improving the potential as well as reducing the side-effects of DOX. Characteristics of nanoparticles were investigated by field emission scanning electron microscopy (FESEM), dynamic light scattering (DLS) method and Fourier transform infrared spectroscopy (FTIR). Anticancer activity of the nanoparticles was evaluated through cytotoxicity and cellular uptake assays on HeLa and HT29 cancer cell lines. The results showed that prepared drug delivery system had size around 100 nm and exhibited higher cytotoxicity and cellular uptake on both tested HeLa and HT29 cells
http://repository.vnu.edu.vn/handle/VNU_123/34087

Tyrosinase inhibitory activity of flavonoids from Artocarpus heterophyllous

Tyrosinase is an oxidoreductase that is very important in medicine and cosmetics because the excessive production of melanin causes hyperpigmentation. The development of novel, effective tyrosinase inhibitors has long been pursued. In preliminary tests, we found that an extract of the wood of Artocarpus heterophyllous (AH) potently inhibited tyrosinase activity. Results: Two new flavonoids, artocaepin E (1) and artocaepin F (2), were isolated from the wood of AH, together with norartocarpetin (3), artocarpanone (4), liquiritigenin (5), steppogenin (6), and dihydromorin (7). Their structures were elucidated using one-dimensional (1D) and two-dimensional (2D) nuclear magnetic resonance (NMR) and mass spectrometry. The absolute configuration of 2 was determined from the circular dichroism (CD) spectrum. Artocarpanone (4) had the most potent tyrosinase inhibitory effect, with an IC50 of 2.0 ± 0.1 μM, followed by artocaepin E (1) and steppogenin (6), with IC50 values of 6.7 ± 0.8 and 7.5 ± 0.5 μM, respectively. A kinetic investigation indicated that 1 showed competitive inhibition, with an inhibition constant (K i) of 6.23 μM. Conclusions: These results demonstrate that extracts of the wood of AH and its phytochemical constituents are potential sources for skin-whitening agents. Graphical abstract Artocarmin E (1) and artocarmin F (2) were isolated from the wood of Artocarpus heterophyllous. Their structures were elucidated using nuclear magnetic resonance analysis and mass spectrometric methods
http://repository.vnu.edu.vn/handle/VNU_123/34089

The Index-based optical spatial modulation scheme in optical MIMO

Optical Multi-Input and Multi-Output (O-MIMO) is considered as an effective solution in order to achieve high performance for Visible Light Communication (VLC) systems. However, O-MIMO systems are faced with the impact of Inter- Channel Interference (ICI) which results in system performance decrease. In this paper, a novel Index-based Optical Spatial Modulation (IOSM) is proposed to remove ICI and increase spectrum efficiency for indoor VLC systems applying O-MIMO. In our proposed scheme, the signals are DC biased for intensity modulation and direct detection (IM/DD) and a Maximumlikelihood (ML) decoder decision to maximize the signal-To-noise ratio (SNR) at the receiver. Computer simulation results show that the proposed scheme outperforms previously proposed spatial modulation schemes in O-MIMO systems.
http://repository.vnu.edu.vn/handle/VNU_123/34090

The nonlinear stability of axisymmetric functionally graded material annular spherical shells under thermo-mechanical load

The authors of this article investigate the nonlinear stability of axisymmetric functionally graded annular spherical shells with temperature-dependent material properties subjected to thermo-mechanical loads and resting on elastic foundations. Equilibrium and compatibility equations are derived by using the classical thin shell theory in terms of the shell deflection and the stress function. Approximate analytical solutions are assumed to satisfy simply supported boundary conditions and Galerkin method is applied to obtain the closed-form of load-deflection paths. An analysis is carried out to show the effects of material and geometrical properties and combination of loads on the stability of the shells.
http://repository.vnu.edu.vn/handle/VNU_123/34091

The Perceived Value of Passive Animal Health Surveillance The Case of Highly Pathogenic Avian Influenza in Vietnam

Economic evaluations are critical for the assessment of the efficiency and sustainability of animal health surveillance systems and the improvement of their efficiency. Methods identifying and quantifying costs and benefits incurred by public and private actors of passive surveillance systems (i.e. actors of veterinary authorities and private actors who may report clinical signs) are needed. This study presents the evaluation of perceived costs and benefits of highly pathogenic avian influenza (HPAI) passive surveillance in Vietnam. Surveys based on participatory epidemiology methods were conducted in three provinces in Vietnam to collect data on costs and benefits resulting from the reporting of HPAI suspicions to veterinary authorities. A quantitative tool based on stated preference methods and participatory techniques was developed and applied to assess the non-monetary costs and benefits. The study showed that poultry farmers are facing several options regarding the management of HPAI suspicions, besides reporting the following: treatment, sale or destruction of animals. The option of reporting was associated with uncertain outcome and transaction costs. Besides, actors anticipated the release of health information to cause a drop of markets prices. This cost was relevant at all levels, including farmers, veterinary authorities and private actors of the upstream sector (feed, chicks and medicine supply). One benefit associated with passive surveillance was the intervention of public services to clean farms and the environment to limit the disease spread. Private actors of the poultry sector valued information on HPAI suspicions (perceived as a non-monetary benefit) which was mainly obtained from other private actors and media.
http://repository.vnu.edu.vn/handle/VNU_123/34092

Apparent digestibility coefficients of feed ingredients for black carp, Mylopharyngodon piceus

The apparent digestibility coefficients of dry matter, crude protein, crude lipid, ash, and gross energy in five test ingredients - fishmeal, meat and bone meal, soybean meal, cornmeal, and brewers yeast (Saccharomyces cerevisiae) - were determined for black carp, Mylopharyngodon piceus (78.3±2.5g), at the Aquaculture Laboratory, Vietnam National University of Agriculture, Vietnam. A reference diet and test diets (a 70:30 mixture of the reference diet to test ingredient) were used with 1% chromic oxide (Cr2O3) as an external indicator. Experimental fish were stocked in 500-L composite tanks at a density of 10 fish per tank. Faeces were collected by faecal collection column. The results indicated that the apparent digestibility coefficients of all test ingredient nutrients, except ash, differed statistically (P < 0.05). The apparent digestibility coefficients were 78.4-90.2% for dry matter, 71.2-92.6% for crude protein, 66.0-87.0% for crude lipid, 52.6-61.9% for ash, and 54.1-80.9% for gross energy. Findings from this study will help formulate cost-effective feed for black carp.
http://repository.vnu.edu.vn/handle/VNU_123/34193

Observation of theΛb0→J/ψ pπ−decay

The first observation of the Cabibbo-suppressed decay Λ b → J/ψpπ is reported using a data sample of proton-proton collisions at 7 and 8 TeV, corresponding to an integrated luminosity of 3 fb-1. A prominent signal is observed and the branching fraction relative to the decay mode Λ b → J/ψpK is determined to be B (Λb → J / ψp π-/ B Λ b → J / ψp K- = 0.0824 ± 0.0025 stat ± 0.0042 syst. A search for direct CP violation is performed. The difference in the CP asymmetries between these two decays is found to be A CP (Λb → J / ψp π-) - A CP (Λb → J / ψp K-) = + 5.7 ± 2.4 stat ± 1.2 syst %, which is compatible with CP symmetry at the 2.2σ level. [Figure not available: see fulltext.]
http://repository.vnu.edu.vn/handle/VNU_123/34194

An experimental investigation on rate sensitivity of fracture-mechanical characteristics in 304 austenitic stainless steel under bending deformation

It is considered that the martensitic transformation in austenitic stainless steel is responsible for its high fracture toughness. A mechanism for fracture mechanical characteristics in the steel at higher rate of deformation might become quite complicated because a quick temperature rise may suppress the martensitic transformation as well as thermal softening. An investigation on fracture-mechanical characteristics of austenitic stainless steel at the higher rate and its rate sensitivity is indispensable. Recently, J-integral of 304 austenitic stainless steel is determined by three-point bending tests at various deflection rates. However, the tests carried out on small specimens might derive some errors for its evaluation because the plane strain condition is not ensured for J-integral. Additionally, the validity of the measured J-integral is not confirmed by other fracture parameters and it is obvious that measured value does not become a critical value of J-integral. In this study, J-integral of the steel is evaluated at different deflection rate by three-point bending tests on larger specimens. As a result, a higher value of J-integral is obtained compared with previous investigation on smaller specimens at the same normalized deflection rate. Additionally, the results indicates that the relationship between value of J-integral and normalized deflection rate is roughly a linear function in a semi-logarithmic plot in the range of normalized deflection rate from 4×10-4 to 10.5/s. The obtained values of the stretch zone width (SZW) are suitable for observation of a positive rate sensitivity of J-integral. Thus, the validity of the results for J-integral is confirmed.
http://repository.vnu.edu.vn/handle/VNU_123/34195

A new integrated fuzzy QFD approach for market segments evaluation and selection

Market segment selection and evaluation are critical marketing activities of all companies. To evaluate and select appropriate market segments, several decision makers and criteria must be involved in the decision process. This study proposes a new integrated fuzzy quality function deployment (QFD) to support the market segment selection and evaluation process. The proposed approach identifies the features that the market segments should have ("WHATs"), in order to fit with the company's business strengths ("HOWs"). In the proposed approach, the relative importance of the "WHATs", the "HOWs"-"WHATs" correlation scores, the resulting weights of the "HOWs", and the impact of each potential market segment, are assessed in linguistic values. The functions of the averaged ratings and averaged weights are then defined, and fuzzy TOPSIS is used to obtain the final ranking of alternatives. The computational procedure of the proposed approach is further illustrated through a case study. Finally, this paper compares the proposed approach with another fuzzy QFD approach, demonstrating the advantages of the proposed approach.
http://repository.vnu.edu.vn/handle/VNU_123/34196

Evaluation of the optimal multiplex PCR method for the detection of aspergillus flavus and aspergillus parasiticus on dried peanut

Aspergillus flavus and Aspergillus parasiticus areq the common aflatoxin producing species that usually infect onq foodstuff in their production line from the field to the storageq place such as peanut, corn, cereal, etc., especially in tropicalq country like Vietnam. Aflatoxins which are considered as derivedq secondary metabolites assigned as a group of mycotoxinsq produced by several species of the Aspergillus spp are potentq hepatotoxins, immunosuppression, carcinogen that lead toq mortality or reducing the productivity of farm animals. Thereq has been a demand for effective method to detect these twoq species on dried food. In previous study, a multiplex PCR methodq were designed to improve the detection process of A. flavusq and A. parasiticus and that method showed high sensitivityq and specificity by being applied on artificially infected driedq peanut. In this study, that multiplex PCR method would beq evaluated by testing the presence of A. flavus and A. parasiticusq on natural dried peanut kernels. On this purpose, the presenceq of A. flavus and A. parasiticus on the collected peanut from theq market was determined using two method, the conventionalq culturing method in Institute of Hygiene and Public Healthq (IHPH) and the mentioned multiplex PCR. The efficiency ofq multiplex PCR method would be evaluated by comparing fungiq detection result of two methods using appropriate statisticalq tests. Next, fungal enrichment with distilled water overnightq was applied to increase the detection percentage if the firstq analysis do not get the expected result. The result showed thatq 54% results from PCR method was the same with culturingq method, and after fungal enrichment, this percentage increasedq to 76% which suggested that these two method was notq significantly different with each other. Therefore, this multiplexq PCR method could have more advanced points than theq culturing method in detection of A. flavus and A. parasiticus onq foodstuff.
http://repository.vnu.edu.vn/handle/VNU_123/34198

Flow Sensitive Information Flow Analysis for C Programs

VITC compiler aims to provide information security to legac y C applications, using type based information flow analysis. We have re- cently modified its typing discipline to flow sensitive, whil e those of the other realistic information secure compiler implementations for Java[5]and ML[8] are flow insensitive. This is because local states in C are toofrequently stored in global variables such as errno
http://repository.vnu.edu.vn/handle/VNU_123/14454

Degradation of diferent types of polyethylene using for lining system exposed to hydro chloride acid solution

This paper focuses on degradation behavior of a maleic anhydride modified and another new modified polyethylene used for lining system as anti-corrosion agent when exposed to hydrochloric acid solution environment. Different concentrations of HCl solution ： 0, 10, and 20 mass％at temperatures of 40, 60, and 80°C were set to investigate the degradation behavior of the two types of modified polyethylene. Virgin PE was also subjected to the same conditions for comparison. Weight change, chloride element penetration, and changes in chemical structure were measured. The immersion test result showed that the diffusion of water and the HCl solution into the neat PE obeyed Fickian diffusion model while those into both modified PE obeyed Fickian mode at low temperatures only. Two-saturation stages were observed for the samples immersed in HCl solutions at 80°C . The modified PE samples were degraded bythe HCl solutions while there was no change of chemical structure for the case of the PE resin. The high temperatureenhanced the order of degradation. IR spectra showed structural changes, which maybe attributed to the modifiercomponents in the polymers.
http://repository.vnu.edu.vn/handle/VNU_123/14461

Diffusion behaviour of corrosive solution environments in carbon black filled modified polyethylene linings

The diffusion behaviour of water and HCl solution at different temperatures and concentrations into a modified polyethylene filled with carbon black used for lining is presented. It has shown the predominant role of nature of environment and carbon black content. In the both environments, an increase of environmental temperature increased the capacity of environmental absorption and the diffusion rate. The lower sorption capacity was observed at 40 and 60 o C while a higher at 80o C in the water. The two-stage diffusion appeared for the case of the corrosive environment at 80o C. An increase of carbon black loading was increased both diffusion rate and saturation values. Diffusion of the environment into the polymer proposed by the following: environmental molecules diffusing into the polymer matrix through porous system, were trapped by functional groups on the carbon black surface and polymer molecule chain, and are immobilized. This explains the increase of sorption capacity when increase carbon black loading.
http://repository.vnu.edu.vn/handle/VNU_123/14462

HANDOVER DECISION IN VISIBLE LIGHT COMMUNICATIONS

VLC is a promising communication technology in which visible light sources such as white Light Emitting Diode (LED) can be utilized as a signal transmitter, the transmission medium is spatial environment, and the appropriate photodiode can be used as a signal receiving component. Despite of many potentially advantages such as: low cost, high speed, power efficient, green communication as well as secure data communication, VLC must deal with the difficulty of distributing LEDs for smooth handover in mobility scenarios and maximize both illumination and communication aspects. In this thesis, we recommend a method to calculate the overlapped area required for smooth handover by sum of the area to make initiation handover occurs and additional area to handover successfully. This thesis is also an efficient configuration method that based on calculated overlapped areas combined with some system constraints such as: sufficient room illumination level, Field of View angle and communication aspects, those are, High Signal to Noise Ratio (SNR), high received power. By transmitting data at different frequencies for each LED lamp, this configuration method can choose the best LED lamp layout setting that gives best performance at both SNR and received power corresponding to that given parameters of room dimension and mobile terminal.
http://repository.vnu.edu.vn/handle/VNU_123/14464

Applying CBR to estimate software costs

Most of current software costs estimation approaches based on statistical models appear to be too complicated and hard to apply in reality. This paper proposes an approach to estimate software costs using Case-Based Reasoning (CBR) where the costs of a new project are estimated by firstly retrieving the similar previous project and then adapting its costs to the current conditions. The project is described as an ontology which allows the managers to estimate with various level of requirement analysis. Moreover, the statistical analysis results of the COCOMO model are utilized to reflect the domain knowledge
http://repository.vnu.edu.vn/handle/VNU_123/14500

Ngữ pháp tiếng Việt dưới góc độ thực hành giao tiếp ứng dụng trong dạy tiếng Việt như một ngoại ngữ

Trình bày một số vấn đề lý thuyết về câu ngôn ngữ, câu giao tiếp, tình thái từ trong cấu tạo câu giao tiếp và đặc điểm tiếng Việt chi phối cú pháp - ngữ nghĩa của câu giao tiếp. Tiến hành khảo sát, điều chỉnh và bổ sung câu giao tiếp cơ bản, phổ dụng trong tiếng Việt. Nghiên cứu kết cấu cú pháp và tiểu từ tình thái phổ dụng trong cấu tạo câu giao tiếp
http://repository.vnu.edu.vn/handle/VNU_123/19291

Nghiên cứu kỹ năng đọc thầm tiếng Anh của học sinh trung học cơ sở

Trên cơ sở giải quyết tốt các nội dung cơ bản này sẽ đề xuất một số ý kiến nhằm nâng cao chất lượng hình thành và phát triển kĩ năng đọc thầm tiếng Anh cho học sinh Việt Nam THCS Đề tài nghiên cứu hiện trạng kĩ năng đọc thầm tiếng Anh của học sinh Việt Nam THCS ở Hà Nội, cụ thể là nghiên cứu các mặt biểu hiện của kĩ năng đọc thầm, các mức độ phát triển của các mặt biểu hiện đó cũng như xác định các yếu tố ảnh hưởng đến sự hình thành và phát triển của kĩ năng này ở học sinh Việt Nam THCS Data KHCN Thư mục kỉ niệm 100 năm ĐHQGHN Nhằm góp phần làm rõ hơn những lý luận về kỹ năng đọc hiểu ngôn ngữ nói chung và tiếng nước ngoài nói riêng để nâng cao chất lượng dạy và học đọc hiểu tiếng nước ngoài, trong đó có tiếng Anh cho học sinh Việt Nam THCS ĐHNN
http://repository.vnu.edu.vn/handle/VNU_123/19138

Nghiên cứu lập luận phản bác bằng tiếng Pháp và ứng dụng vào giảng dạy cho sinh viên chuyên ngữ Việt Nam

Trình bày khái niệm lập luận, sự khác nhau giữa lập luận và chứng minh, lô gích. Vai trò của các lẽ thường trong lập luận. Các tác tử và kết tử trong lập luận, các thao tác lập luận, lập luận và phản bác, sự khác nhau giữa phản bác và biện hộ. Vấn đề giảng dạy lập luận, phản bác cho sinh viên chuyên ngữ tiếng Pháp, những khó khăn, thuận lợi và một số giải pháp
http://repository.vnu.edu.vn/handle/VNU_123/21632

Nghiên cứu đặc điểm hình thức và ngữ nghĩa của các kiểu câu điều kiện trong tiếng Việt : Bản tóm tắt

Thông qua các khuynh hướng nghiên cứu câu điều kiện trên thế giới đi sâu nghiên cứu đặc điểm hình thức của các kiểu câu điều kiện Tiếng Việt . Tìm ra cấu trúc câu điều kiện căn bản trong Tiếng Việt. Đồng thời phân tích tham số của câu điều kiện Tiếng Việt ( liên từ điều kiện, quan hệ giữa mệnh đề điều kiện và mệnh đề chính). Từ đó phân tích và phân loại thành 6 kiểu câu điều kiện căn bản dựa vào cơ sở chính là quan hệ ngữ nghĩa giữa 2 mệnh đề trong câu điều kiện
http://repository.vnu.edu.vn/handle/VNU_123/22562

Giới từ tiếng Việt biểu đạt ý nghĩa không gian- thời gian và ứng dụng chúng trong việc dạy tiếng Việt như một ngoại ngữ

Đề tài khảo sát những đặc điểm ngữ pháp - ngữ nghĩa của các giới từ tiếng Việt biểu thị quan hệ vị trí của sự vật trong không gian và thời gian và so sánh những đặc trưng của chúng với những đơn vị tương ứng của tiếng Anh nhằm phục vụ cho việc dạy tiếng Việt thực hành như một ngoại ngữ Data KHCN Thư mục kỉ niệm 100 năm ĐHQGHN
http://repository.vnu.edu.vn/handle/VNU_123/19146

Phân lập và tuyển chọn một số chủng vi sinh vật có khả năng xử lý phế phụ phẩm nông nghiệp

Tổng quan về phế phụ phẩm trồng trọt và chăn nuôi cũng như ảnh hưởng của chúng đến môi trường. Giới thiệu vai trò của vi sinh vật trong việc xử lý các phế thải hữu cơ. Trình bày quá trình nghiên cứu từ 14 chủng vi sinh vật đã tuyển chọn được 2 chủng có hoạt tính phân giải xenlulozơ cao và 2 chủng có hoạt tính phân giải tinh bột cao. Các chủng này thuộc nhóm ưa nhiệt và ưa pH từ 7-8. Chỉ ra rằng các chủng này có thể sử dụng để xử lý rơm rạ làm phân bón. Khi ủ phế thải chăn nuôi bằng vi sinh vật đã rút ngắn thời gian ủ từ 3 - 6 lần so với phương pháp truyền thống mà hàm lượng các chất dinh dưỡng lại cao hơn, từ đó nâng cao năng suất cây trồng lên khoảng 22.5%. Bên cạnh đó, sản phẩm lại không chứa vi sinh vật gây bệnh nên an toàn cho người sử dụng
http://repository.vnu.edu.vn/handle/VNU_123/23115

Xử lí lá mía làm phân bón hữu cơ và giải quyết ô nhiễm môi trường nông thôn bằng biện pháp vi sinh vật

Tạo công nghệ sản xuất phân bón hữu cơ từ lá mía hoặc phế phụ phẩm nông nghiệp bằng chế phẩm vi sinh vật : qua việc phân lập tuyển chọn một bộ giống vi sinh vật bao gồm vi khuẩn, xạ khuẩn có khả năng phân giải các hợp chất hữu cơ, có khả năng sinh trưởng nhanh trên môi trường đơn giản, không độc hại. Giúp bà con nông dân tự sản xuất phân bón ngay tại đồng ruộng, giảm thiểu ô nhiễm môi trường nông thôn

http://repository.vnu.edu.vn/handle/VNU_123/22057

Nghiên cứu ảnh hưởng của chất thải nhà máy và bệnh viện đến khu hệ vi sinh vật đất

Cần mở rộng quy mô nghiên cứu trên các địa bàn khác nhau.Từ đó đề ra các duy định hoặc luật pháp về vấn đề sử lý chất thải của nhà máy và bệnh viện trước khi thải ra môi trường Chất thải của các bệnh viện đã nghiên cứu ảnh hưởng lớn đến hệ sinh thái vi sinh vật đất.Số lượng coliform trong các mẫu nước quanh bệnh viện tăng cao, đã nói lên mức độ ô nhiễm vi sinh quanh khu vực bệnh viện Chất thải của các nhà máy trong phạm vi nghiên cứu ảnh hưởng rõ rệt đến hệ sinh thái vi sịnh vật đất.Nhóm vi khuẩn hiến khí và loại hình canh tác lúa nước chịu ảnh hưởng nhiểu nhất của chất thải
http://repository.vnu.edu.vn/handle/VNU_123/22285

Tuyển chọn các chủng xạ khuẩn có khả năng ức chế sinh trưởng một số vi sinh vật gây bệnh thực vật và đặc tính sinh học của chúng

Giới thiệu chung về bệnh héo xanh do vi khuẩn Pseudomonas solanacearum, héo vàng do vi nấm Fusarium oxysporum, quá trinh Nitrat hoá, Xạ khuẩn và khả năng ức chế vi sinh vật gây bệnh ở cây trồng.Giới thiệu các chủng vi sinh vật dùng trong nghiên cứu, phương pháp nghiên cứu .Kết quả nghiên cứu về khả năng ức chế của các chủng xạ khuẩn đối với vi nấm Fusarium oxysporum , vi khuẩn nitrat hoá và vi khuẩn héo xanh. Tìm ra những chủng xạ khuẩn có khả năng ức chế sinh trưởng của một số sinh vật gây bệnh ở cây trồng nhằm sản xuất chế phẩm sinh học bảo vệ thực vật, hạn chế sử dụng hoá chất bảo vệ thực vật Thử hoạt tính kháng nấm của 80 chủng xạ khuẩn, có 17 chủng có hoạt tính chiếm 21%, trong đó có 3 chủng có hoạt lực cực mạnh. Thử hoạt tính kháng vi khuẩn nitrat hoá của 27 chủng xạ khuẩn có 13 chủng có hoạt tính, trong đó có 2 chủng có hoạt lực mạnh Thử hoạt tính kháng vi khuẩn gây bệnh héo xanh của 60 chủng xạ khuẩn. Trong đó có 40 chủng có hoạt tính chiếm 66,7%, có 5 chủng có hoạt tính mạnh với các loại vi khuẩn héo xanh thuộc các loại cây trồng khác nhau.
http://repository.vnu.edu.vn/handle/VNU_123/19175

Nghiên cứu sử dụng hệ enzym cellulase tách từ vi sinh vật để phân giải cellulose trong phế thải nông nghiệp

Nghiên cứu tách hệ enzym cellulase tách từ vi sinh vật. Sử dụng hệ enzym cellulase tách từ vi sinh vật để phân giải cellulase trong rơm rạ. Kết quả xác định khả năng phân giải Cellulose và hoạt động enzyme cellulase tách từ hai chủng xạ khuẩn 2P, 7P và 2 chủng vi khuẩn C32, C36 cho thấy, chủng xạ khuẩn 2P có hoạt tính enzyme cellulase cao nhất, có khả năng phân giải cellulose lớn nhất trong 4 chủng vi sinh được nghiên cứu. Rơm rạ phân hủy có sự tham gia của enzyme cellulase tách từ chủng xạ khuẩn 2P có nồng độ nitơ tổng số lớn hơn 42,9% so với nồng độ nitơ trong mẫu rơm rạ phân hủy tự nhiên. Như vậy, có thể sử dụng dịch enzyme tách từ xạ khuẩn 2P trong chế phẩm vi sinh để xử lý phế thải nông nghiệp làm phân bón cho cây trồng một cách hiệu quả, phục vụ nền sản xuất nông nghiệp sạch, góp phần bảo vệ môi trường và phát triển bền vững.
http://repository.vnu.edu.vn/handle/VNU_123/23462