Anh Tú - Academia.edu (original) (raw)

Papers by Anh Tú

This paper has been withdrawn by the author because in the main text some discussion parts were i... more This paper has been withdrawn by the author because in the main text some discussion parts were inadvertently added by mistake.

Expression of the upp gene of Escherichia coli, which encodes the pyrimidine salvage enzyme uraci... more Expression of the upp gene of Escherichia coli, which encodes the pyrimidine salvage enzyme uracil phosphoribosyltransferase, is negatively regulated by pyrimidine availability. In this study, we demonstrate that this regulation occurs mainly by UTP-sensitive selection of alternative transcriptional start sites, which produces transcripts that differ in the ability to be productively elongated. The upp initially transcribed region contains the sequence GATTTTTTTTG (nontemplate strand). Transcription is initiated primarily at the first two bases in this sequence, designated G6 and A7 (counting from the promoter ؊10 region). High intracellular levels of UTP favor initiation at position A7; however, the resulting transcripts are subject to reiterative transcription (i.e., repetitive nucleotide addition) within the run of T residues in the initially transcribed region. The resulting AUUUU n (where n ‫؍‬ 1 to >50) transcripts are not extended to include downstream upp sequences. In contrast, low intracellular levels of UTP strongly favor initiation at position G6, which results in transcripts that generally do not engage in reiterative transcription and thus can be normally elongated. This mechanism ensures that high levels of uracil phosphoribosyltransferase are produced only under conditions of pyrimidine limitation. The mechanisms that account for UTP-sensitive start site selection and different fates of upp transcripts, as well as the general use of UTP-dependent reiterative transcription in gene regulation, are discussed in detail.

Advances in Natural Sciences: Nanoscience and Nanotechnology, 2010

Oxide dispersion strengthened (ODS) steels, manufactured by a mechanical alloying method, during ... more Oxide dispersion strengthened (ODS) steels, manufactured by a mechanical alloying method, during the past few years, appear to be promising candidates for structural applications in nuclear power plants. The purpose of this work is to elaborate the manufacturing processes of ODS 13Cr steel with the addition of 1.0 wt% yttrium oxide through the powder metallurgy route using the high energy ball mill. Microstructural analysis by scanning electron microscopy (SEM), x-ray diffraction (XRD) and hardness testing have been used to optimize the technological parameters of milling, hot isostatic pressing and heat-treatment processes. The steel hardness increases with decreasing particle size of 13Cr ODS steel. The best hardness was obtained from more than 70 h of milling in the two tanks planetary ball mill or 30 h of milling in the one tank planetary ball mill and hot isostatic pressing at 1150 • C . The particle size of the steel is less than 100 nm, and the density and hardness are about 7.3 g cm −3 and 490 HB, respectively.

Colloids and Surfaces A-physicochemical and Engineering Aspects, 2003

Mesoscopic structures made of cigar-shaped maghemite (␥-Fe 2 O 3 ) nanocrystals differing by thei... more Mesoscopic structures made of cigar-shaped maghemite (␥-Fe 2 O 3 ) nanocrystals differing by their sizes are described. The structures were prepared by slow evaporation of a dilute suspension of nanocrystals, to which could be applied a magnetic field parallel to the substrate. If a magnetic field was applied, the nanocrystals rotated their long axis along the magnetic field direction to form ribbons whereas without a field the nanocrystals remained deposited on the substrate with a random orientation. The aligned nanocrystals is responsible of the anisotropy of the ribbons as evidence by the hysteresis loops. Moreover, a high demagnetizing field is observed when the magnetization measurements are made with an applied field normal to the ribbons. (M.P. Pileni). but none for 3D superlattices. For non-magnetic material, 3D "supra" crystals of nanoparticles are produced [3]. By controlling substrate temperature and evaporation rate "supra" crystals made of more than a thousand layers of nanocrystals are obtained. With magnetic nanocrystals, until now, it was impossible to produce "supra" crystals. However very recently [4], in our laboratory, we have been able to make large "supra" crystals. This provides great hope and a fascinating new field of physical chemistry. These artificial structures can be manipulated to achieve tailored materials for application and for exploration of physical phenomena, as the magnetic properties of this new class of materials should, as with dense films, differ both from those of individual nanoparticles and bulk materials.

Modern wireless networks, such as WiMAX or LTE are using OFDM/OFDMA as the enabling technologies ... more Modern wireless networks, such as WiMAX or LTE are using OFDM/OFDMA as the enabling technologies for broadband transmission in cellular environments with QoS capabilities. In these networks, such schema as radio resource management, admission control, scheduling are essential. In this article we firstly introduce a Time-Frequency Burst Mapping algorithm for radio resource management that improves the spectral efficiency of OFDMA/TDD channel. A Frame-based Weighted Fair Queueing (F-WFQ) Algorithm, which is a modified version of the conventional WFQ and suitable for operations in OFDMA/TDD environments is also proposed. When combining the two algorithms, we point out that the spectral efficiency can be maintained, while fairness, delay and proportional throughput of backlog sessions are greatly improved in comparison to the conventional Proportional Fair scheduling algorithm.

Clinical Therapeutics, 2010

The main aims of this work were to describe patterns of medication use in the treatment of chroni... more The main aims of this work were to describe patterns of medication use in the treatment of chronic hepatitis B virus (HBV) infection in patients in the northern part of the Netherlands and to compare these practices with established guidelines. In addition, the duration of use and the costs of these treatments were investigated.

For high temperature automotive application, IC products are required to pass stringent high temp... more For high temperature automotive application, IC products are required to pass stringent high temperature storage stress test (e.g. 5000hrs at 150 deg C), hence requires reliable wire bonds. Such requirement is especially challenging with fine pitch Au & Cu wire bond (e.g. bond pad pitch >; 70um and bonded ball diameter <; 58um), more-so on low k wafer technology with bond-over-active requirement. In the area of fine pitch wire bond reliability of an IC product, Au wire on Al pad is known to have ball bond failure after prolong thermal aging at elevated temperature. Studies have shown that the root cause is due to diffusion of Au during intermetallic phase transformation, resulted in excessive Al precipitation. Void formation proven to be associated with oxidation (corrosion) process of excessive Al precipitated during intermetallic phase transformation. Bond fails due to void coalescence and crack propagation in IMC level. Hence, to prevent bond failures especially during high temperature thermal aging, over-pad metallization (OPM) with NiPdAu plating is an option by inhibiting the diffusion of Au in the intermetallic (non Au Al type), hence prevents/minimizes void formation. It also helps to reduce stress on bond pads during wire bonding. In view of the need for characterization of over-pad metallization, a study was conducted to understand fine pitch Au and Cu wire bond integrity vs. different Ni thickness of NiPdAu bond pad on C90 Low k wafer technology to meet high temperature automotive requirement. The result of this study showed that OPM greatly helped in the improvement of ball bond integrity to meet high temperature automotive requirement, 1um Ni thickness was found to have pad sinking effect, hence the preferred Ni plating thickness was minimum 2um. For cost saving purpose, the combination of Cu wire with 2um is recommended.

Asean Economic Bulletin, 1996

Tumor necrosis factor alpha (TNF-␣) is important in resistance to various microorganisms and prov... more Tumor necrosis factor alpha (TNF-␣) is important in resistance to various microorganisms and provides signals to the target cells through two different receptors, TNF-␣ receptor I (TNFRI) (p55 receptor) and TNFRII (p75 receptor). To delineate the significance of the two different signaling pathways in resisting infections with extracellular bacteria, we examined the resistance of mice to Streptococcus pneumoniae (serotype 6B). TNF-␣ needs to be present early in infections, since one injection of wild-type mice with anti-TNF-␣ leads to an increased susceptibility of these mice to S. pneumoniae. TNF-␣ signaling through the p55 receptor (but not the p75 receptor) is crucial in resisting S. pneumoniae infections, because intraperitoneal injection of 100 CFU/ mouse killed p55-deficient mice by day 2 of infection, whereas 1,000,000 CFU/mouse was needed to kill half of the control mice. p55-deficient mice do not show evidence of a deficient acute-phase response. All three types of mice (p55 deficient, p75 deficient, and normal) showed comparable rises in the levels of two acute-phase proteins (serum amyloid P and C3) at 24, 48, and 72 h after the experimental infections, and all of the mice showed comparable influxes of neutrophils to the site of infection. Finally, it was demonstrated that p55-deficient mice can be protected from the lethal effects of S. pneumoniae infection by injection of antibodies specific for S. pneumoniae polysaccharide capsule.

Dạng 1: Hoàn thành sơ đồ phản ứng 1. Phương pháp:  Cần nắm chắc kiến thức về tính chất hoá học, ... more Dạng 1: Hoàn thành sơ đồ phản ứng 1. Phương pháp:  Cần nắm chắc kiến thức về tính chất hoá học, phương pháp điều chế các chất, đặc biệt về các chất thuộc nhóm nitơ như N2, NO, NO2, HNO3, NH3, muối nitrat, muối amoni, H3PO4, muối photphat…  Cần nhớ: Mỗi mũi tên trong sơ đồ nhất thiết chỉ biểu diễn bằng một phản ứng. 2. Ví dụ Ví dụ 1: Sơ đồ phản ứng sau đây cho thấy rõ vai trò của thiên nhiên và con người trong việc chuyển nitơ từ khí quyển vào trong đất, cung cấp nguồn phân đạm cho cây cối:

This paper has been withdrawn by the author because in the main text some discussion parts were i... more This paper has been withdrawn by the author because in the main text some discussion parts were inadvertently added by mistake.

Expression of the upp gene of Escherichia coli, which encodes the pyrimidine salvage enzyme uraci... more Expression of the upp gene of Escherichia coli, which encodes the pyrimidine salvage enzyme uracil phosphoribosyltransferase, is negatively regulated by pyrimidine availability. In this study, we demonstrate that this regulation occurs mainly by UTP-sensitive selection of alternative transcriptional start sites, which produces transcripts that differ in the ability to be productively elongated. The upp initially transcribed region contains the sequence GATTTTTTTTG (nontemplate strand). Transcription is initiated primarily at the first two bases in this sequence, designated G6 and A7 (counting from the promoter ؊10 region). High intracellular levels of UTP favor initiation at position A7; however, the resulting transcripts are subject to reiterative transcription (i.e., repetitive nucleotide addition) within the run of T residues in the initially transcribed region. The resulting AUUUU n (where n ‫؍‬ 1 to >50) transcripts are not extended to include downstream upp sequences. In contrast, low intracellular levels of UTP strongly favor initiation at position G6, which results in transcripts that generally do not engage in reiterative transcription and thus can be normally elongated. This mechanism ensures that high levels of uracil phosphoribosyltransferase are produced only under conditions of pyrimidine limitation. The mechanisms that account for UTP-sensitive start site selection and different fates of upp transcripts, as well as the general use of UTP-dependent reiterative transcription in gene regulation, are discussed in detail.

Advances in Natural Sciences: Nanoscience and Nanotechnology, 2010

Oxide dispersion strengthened (ODS) steels, manufactured by a mechanical alloying method, during ... more Oxide dispersion strengthened (ODS) steels, manufactured by a mechanical alloying method, during the past few years, appear to be promising candidates for structural applications in nuclear power plants. The purpose of this work is to elaborate the manufacturing processes of ODS 13Cr steel with the addition of 1.0 wt% yttrium oxide through the powder metallurgy route using the high energy ball mill. Microstructural analysis by scanning electron microscopy (SEM), x-ray diffraction (XRD) and hardness testing have been used to optimize the technological parameters of milling, hot isostatic pressing and heat-treatment processes. The steel hardness increases with decreasing particle size of 13Cr ODS steel. The best hardness was obtained from more than 70 h of milling in the two tanks planetary ball mill or 30 h of milling in the one tank planetary ball mill and hot isostatic pressing at 1150 • C . The particle size of the steel is less than 100 nm, and the density and hardness are about 7.3 g cm −3 and 490 HB, respectively.

Colloids and Surfaces A-physicochemical and Engineering Aspects, 2003

Mesoscopic structures made of cigar-shaped maghemite (␥-Fe 2 O 3 ) nanocrystals differing by thei... more Mesoscopic structures made of cigar-shaped maghemite (␥-Fe 2 O 3 ) nanocrystals differing by their sizes are described. The structures were prepared by slow evaporation of a dilute suspension of nanocrystals, to which could be applied a magnetic field parallel to the substrate. If a magnetic field was applied, the nanocrystals rotated their long axis along the magnetic field direction to form ribbons whereas without a field the nanocrystals remained deposited on the substrate with a random orientation. The aligned nanocrystals is responsible of the anisotropy of the ribbons as evidence by the hysteresis loops. Moreover, a high demagnetizing field is observed when the magnetization measurements are made with an applied field normal to the ribbons. (M.P. Pileni). but none for 3D superlattices. For non-magnetic material, 3D "supra" crystals of nanoparticles are produced [3]. By controlling substrate temperature and evaporation rate "supra" crystals made of more than a thousand layers of nanocrystals are obtained. With magnetic nanocrystals, until now, it was impossible to produce "supra" crystals. However very recently [4], in our laboratory, we have been able to make large "supra" crystals. This provides great hope and a fascinating new field of physical chemistry. These artificial structures can be manipulated to achieve tailored materials for application and for exploration of physical phenomena, as the magnetic properties of this new class of materials should, as with dense films, differ both from those of individual nanoparticles and bulk materials.

Modern wireless networks, such as WiMAX or LTE are using OFDM/OFDMA as the enabling technologies ... more Modern wireless networks, such as WiMAX or LTE are using OFDM/OFDMA as the enabling technologies for broadband transmission in cellular environments with QoS capabilities. In these networks, such schema as radio resource management, admission control, scheduling are essential. In this article we firstly introduce a Time-Frequency Burst Mapping algorithm for radio resource management that improves the spectral efficiency of OFDMA/TDD channel. A Frame-based Weighted Fair Queueing (F-WFQ) Algorithm, which is a modified version of the conventional WFQ and suitable for operations in OFDMA/TDD environments is also proposed. When combining the two algorithms, we point out that the spectral efficiency can be maintained, while fairness, delay and proportional throughput of backlog sessions are greatly improved in comparison to the conventional Proportional Fair scheduling algorithm.

Clinical Therapeutics, 2010

The main aims of this work were to describe patterns of medication use in the treatment of chroni... more The main aims of this work were to describe patterns of medication use in the treatment of chronic hepatitis B virus (HBV) infection in patients in the northern part of the Netherlands and to compare these practices with established guidelines. In addition, the duration of use and the costs of these treatments were investigated.

For high temperature automotive application, IC products are required to pass stringent high temp... more For high temperature automotive application, IC products are required to pass stringent high temperature storage stress test (e.g. 5000hrs at 150 deg C), hence requires reliable wire bonds. Such requirement is especially challenging with fine pitch Au & Cu wire bond (e.g. bond pad pitch >; 70um and bonded ball diameter <; 58um), more-so on low k wafer technology with bond-over-active requirement. In the area of fine pitch wire bond reliability of an IC product, Au wire on Al pad is known to have ball bond failure after prolong thermal aging at elevated temperature. Studies have shown that the root cause is due to diffusion of Au during intermetallic phase transformation, resulted in excessive Al precipitation. Void formation proven to be associated with oxidation (corrosion) process of excessive Al precipitated during intermetallic phase transformation. Bond fails due to void coalescence and crack propagation in IMC level. Hence, to prevent bond failures especially during high temperature thermal aging, over-pad metallization (OPM) with NiPdAu plating is an option by inhibiting the diffusion of Au in the intermetallic (non Au Al type), hence prevents/minimizes void formation. It also helps to reduce stress on bond pads during wire bonding. In view of the need for characterization of over-pad metallization, a study was conducted to understand fine pitch Au and Cu wire bond integrity vs. different Ni thickness of NiPdAu bond pad on C90 Low k wafer technology to meet high temperature automotive requirement. The result of this study showed that OPM greatly helped in the improvement of ball bond integrity to meet high temperature automotive requirement, 1um Ni thickness was found to have pad sinking effect, hence the preferred Ni plating thickness was minimum 2um. For cost saving purpose, the combination of Cu wire with 2um is recommended.

Asean Economic Bulletin, 1996

Tumor necrosis factor alpha (TNF-␣) is important in resistance to various microorganisms and prov... more Tumor necrosis factor alpha (TNF-␣) is important in resistance to various microorganisms and provides signals to the target cells through two different receptors, TNF-␣ receptor I (TNFRI) (p55 receptor) and TNFRII (p75 receptor). To delineate the significance of the two different signaling pathways in resisting infections with extracellular bacteria, we examined the resistance of mice to Streptococcus pneumoniae (serotype 6B). TNF-␣ needs to be present early in infections, since one injection of wild-type mice with anti-TNF-␣ leads to an increased susceptibility of these mice to S. pneumoniae. TNF-␣ signaling through the p55 receptor (but not the p75 receptor) is crucial in resisting S. pneumoniae infections, because intraperitoneal injection of 100 CFU/ mouse killed p55-deficient mice by day 2 of infection, whereas 1,000,000 CFU/mouse was needed to kill half of the control mice. p55-deficient mice do not show evidence of a deficient acute-phase response. All three types of mice (p55 deficient, p75 deficient, and normal) showed comparable rises in the levels of two acute-phase proteins (serum amyloid P and C3) at 24, 48, and 72 h after the experimental infections, and all of the mice showed comparable influxes of neutrophils to the site of infection. Finally, it was demonstrated that p55-deficient mice can be protected from the lethal effects of S. pneumoniae infection by injection of antibodies specific for S. pneumoniae polysaccharide capsule.

Dạng 1: Hoàn thành sơ đồ phản ứng 1. Phương pháp:  Cần nắm chắc kiến thức về tính chất hoá học, ... more Dạng 1: Hoàn thành sơ đồ phản ứng 1. Phương pháp:  Cần nắm chắc kiến thức về tính chất hoá học, phương pháp điều chế các chất, đặc biệt về các chất thuộc nhóm nitơ như N2, NO, NO2, HNO3, NH3, muối nitrat, muối amoni, H3PO4, muối photphat…  Cần nhớ: Mỗi mũi tên trong sơ đồ nhất thiết chỉ biểu diễn bằng một phản ứng. 2. Ví dụ Ví dụ 1: Sơ đồ phản ứng sau đây cho thấy rõ vai trò của thiên nhiên và con người trong việc chuyển nitơ từ khí quyển vào trong đất, cung cấp nguồn phân đạm cho cây cối: