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Search Results: 1 - 10 of 4675 matches for " Thuy Nguyen "
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Application of D-Optimal Study Design with Contour Surface Response for Designing Sustained Release Gliclazide Matrix Tablets  [PDF]
Chien Nguyen, John Mark Christensen, Thuy Nguyen
Pharmacology & Pharmacy (PP) , 2014, DOI: 10.4236/pp.2014.57072
Abstract:

An optimized formulation of a sustained release tablet of Gliclazide was developed. The use of Doptimal design with a polynomial statistical model to analyze dissolution data reduced the number of laboratory tests required to obtain an optimal dosage form. The final formulation contained 22 mg of Methocel®E15LV, 16.5 mg Methocel®E15 and 10.0 mg of Dibasic Calcium Phosphate per 30 mg Gliclazide sustained release tablet. Dissolution studies performed on tablets from 5000 tablet test batches released greater than 90 percent of loaded drug in eight hours. Drug release from the optimized tablets followed a pattern more closely similar to zero-order than other mechanisms of drug release tested. Storage of tablets in accelerated and ambient conditions for 6 and 12 months respectively did not alter any of the physico-chemical properties, drug release or the drug release rate compared to initial observations and dissolution data of the prepared tablets. The addition of potassium phosphate and monosodium phosphate to the tablet reduced the effect pH has on Gliclazide dissolution compared to the commercially available product.

Regularization of ill-posed mixed variational inequalities with non-monotone perturbations
Thuy Nguyen
Journal of Inequalities and Applications , 2011,
Abstract: In this paper, we study a regularization method for ill-posed mixed variational inequalities with non-monotone perturbations in Banach spaces. The convergence and convergence rates of regularized solutions are established by using a priori and a posteriori regularization parameter choice that is based upon the generalized discrepancy principle.
Carleman estimates for semi-discrete parabolic operators with a discontinuous diffusion coefficient and application to controllability
Thuy Nguyen
Mathematics , 2012,
Abstract: In the discrete setting of one-dimensional finite-differences we prove a Carleman estimate for a semi-discretization of the parabolic operator $\partial_t-\partial_x (c\partial_x)$ where the diffusion coefficient $c$ has a jump. As a consequence of this Carleman estimate, we deduce consistent null-controllability results for classes of semi-linear parabolic equations.
The uniform controllability property of semidiscrete approximations for the parabolic distributed parameter systems in Banach spaces
Thuy Nguyen
Mathematics , 2011,
Abstract: The problem we consider in this work is to minimize the L^q-norm (q > 2) of the semidiscrete controls. As shown in [LT06], under the main approximation assumptions that the discretized semigroup is uniformly analytic and that the degree of unboundedness of control operator is lower than 1/2, the uniform controllability property of semidiscrete approximations for the parabolic systems is achieved in L^2. In the present paper, we show that the uniform controllability property still continue to be asserted in L^q. (q > 2) even with the con- dition that the degree of unboundedness of control operator is greater than 1/2. Moreover, the minimization procedure to compute the ap- proximation controls is provided. An example of application is imple- mented for the one dimensional heat equation with Dirichlet boundary control.
Jaundice in Adult in-Patients at a Tertiary General Hospital  [PDF]
Le Ngoc Hung, Nguyen Thi Le Huong, Nguyen Thi Thuy An
Journal of Biosciences and Medicines (JBM) , 2015, DOI: 10.4236/jbm.2015.32001
Abstract: Objective: The aim of the study is to investigate the “new-onset jaundice” incidence, map of causes, approaching method, and risk factors for treatment failure in adult in-patients at a tertiary general hospital as Cho Ray Hospital, Ho Chi Minh City, Viet Nam. Method: Retrospective study was done on 416 jaundice patients administered over 38 continuous days. Laboratory tests investigated were total bilirubin, direct bilirubin, AST, ALT, AST/ALT ratio, GGT, AP, bilirubin and urobilinogen in urine. Jaundice was defined as total bilirubin ≥ 2.5 mg/dL, direct bilirubin jaundice defined as direct bilirubin > 2 mg/dL and D/T percentage > 60%, the severity of AST, ALT evaluated according to Common Terminology Criteria for Adverse Events, AST/ALT ratio, and bilirubin, urobilinogen in urine. Outcome of treatment were classified in two groups: failure (dead or discharge due to worse status) and success. Descriptive statistics and analytic statistics were applied, mono-variable analysis and multinomial logistic regression to find out the independent risk factors for treatment failure. Results: The incidence of “new-onset” jaundice in adult patients was 11 ± 5 person/day. The map of jaundice included 3 phases as pre-heaptic 13.7%, in-hepatic 58.2%, and post-hepatic 22.8%. Pancreatic and biliary tract diseases accounted 17.1%, then cirrhosis 16.3%, liver tumor 14.7%, hepatitis 8.9%, sepsis 8.9%, hematology diseases 7.9%, and cardiac diseases 7.5%. A guide for approaching causes of jaundice basing on 7 parameters as total bilirubin, D/T percentage, severity of ALT, AST/ALT ratio, severity of GGT, and bilirubin and urobilinogen in urine was established. The overall mortality was 7.5% (31/416), sepsis had highest death rate of 37.8% (14/37). Sepsis and AST/ALT ratio > 2 were the two independent risk factors of mortality. Conclusion: At tertiary hospital, jaundice is common sign in adult patient, diverse enormously in many clinical wards. The map of causes of jaundice completed all 3 phases: pre-hepatic, intra-hepatic and post-hepatic phase. Drug hepatitis jaundice was an important cause in hepatitis. Sepsis had highest mortality in adult jaundice patients. Combination of 7 criteria as total bilirubin, the D/T percentage, ALT severity, AST/ALT ratio, GGT, bilirubin and urobilinogen in urine gave the guide for approaching to jaundice. Sepsis and AST/ALT ratio > 2 were independent risk factors of treatment failure. The survey of jaundice in adult in-patients in a tertiary general government hospital gave the full picture for this common pathological sign.
La méthode des fa?ons
Nguyen Thi Bich Thuy
Mathematics , 2014,
Abstract: We give in this article a natural method that we call la m\'ethode des fa\c{c}ons to stratify the asymptotic variety associated to a polynomial map. The obtained stratification is a semi-algebraic, differentiable stratification and is a Thom-Mather stratification.
An algorithm to classify the asymptotic set associated to a polynomial mapping
Nguyen Thi Bich Thuy
Mathematics , 2015,
Abstract: We provide an algorithm to classify the asymptotic set associated to a dominant polynomial mapping $F: \C^n \to \C^n$, using the so-called "{\it m\'ethode des fa{\c c}ons}" in \cite{Thuy}. We obtain a classification theorem for the asymptotic sets of dominant polynomial mappings.
A remark on a polynomial mapping $F: \C^n \to \C^{n}$
Nguyen Thi Bich Thuy
Mathematics , 2015,
Abstract: In \cite{Valette}, Guillaume and Anna Valette associate singular varieties $V_F$ to a polynomial mapping $F: \C^n \to \C^n$. In the case $F: \C^2 \to \C^2$, if the set $K_0(F)$ of critical values of $F$ is empty, then $F$ is not proper if and only if the 2-dimensional homology or intersection homology (with any perversity) of $V_F$ are not trivial. In \cite{ThuyValette}, the results of \cite{Valette} are generalized in the case $F: \C^n \to \C^n$ where $n \geq 3$, with an additional condition. In this paper, we prove that if $F: \C^2 \to \C^2$ is a non-proper {\it generic dominant} polynomial mapping, then the 2-dimensional homology and intersection homology (with any perversity) of $V_F$ are not trivial. We prove that this result is true also for a non-proper {\it generic dominant} polynomial mapping $F: \C^n \to \C^n$ ($\, n \geq 3$), with the same additional condition than in \cite{ThuyValette}. In order to compute the intersection homology of the variety $V_F$, we provide an explicit Thom-Mather stratification of the set $K_0(F) \cup S_F$.
A Remark on Polynomial Mappings from Cn to Cn-1 and an Application of the Software Maple in Research  [PDF]
Thi Bich Thuy Nguyen
Applied Mathematics (AM) , 2016, DOI: 10.4236/am.2016.715154
Abstract: In [1], we construct singular varieties \"\" associated to a polynomial mapping \"\" where \"\" such that if G is a local submersion but is not a fibration, then the 2-dimensional homology and intersection homology (with total perversity) of the variety \"\" are not trivial. In [2], the authors prove that if there exists a so-called very good projection with respect to the regular value \"\" of a polynomial mapping \"\", then this value is an atypical value of G if and only if the Euler characteristic of the fibers is not constant. This paper provides relations of the results obtained in the articles [1] and [2]. Moreover, we provide some examples to illustrate these relations, using the software Maple to complete the calculations of the examples. We provide some discussions on these relations. This paper is an example for graduate students to apply a software that they study in the graduate program in advanced researches.
Determination of ppt Level Chromium(VI) Using the Gold Nano-Flakes Electrodeposited on Platinum Rotating Disk Electrode and Modified with 4-Thiopyridinium  [PDF]
Huy Du Nguyen, T. Thuy Luyen Nguyen, Khac Manh Nguyen, T. Anh Tuyet Tran, Anh Mai Nguyen, Quoc Hien Nguyen
American Journal of Analytical Chemistry (AJAC) , 2015, DOI: 10.4236/ajac.2015.65045
Abstract: The nano-gold layer formed on the platinum rotating disk electrode (nano-Au/Pt-RD) inherited the catalytic property for Cr(VI) reduction from platinum surface and owned the good features of nano-gold such as insensitivity with hydrogen ion, high surface area, augmenting diffusion of Cr(VI) and ability for self-assembling with 4-pyridine-ethanethiol (PET) through Au←S linkages, to form PET/nano-Au/Pt-RD electrode capable of accumulating Cr(VI) from sample. The obtained PET/ nano-Au/Pt-RD electrode showed an extreme sensitivity to Cr(VI). By using this electrode, 1.09 ng·L﹣1 was the detection limit of differential pulse adsorptive cathodic stripping voltammetry for Cr(VI) with the accumulation time of only 2 min. Moreover, this electrode was reproducible with 3.5% RSD for 30 times of Cr(VI) accumulating and stripping. In addition, this electrode was also selective for Cr(VI) determination, which was not almost interfered by other inorganic ions.
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