ZnO nanostructures with different morphologies of nanorods, nanoneedles, nanowires, and nanobelts... more ZnO nanostructures with different morphologies of nanorods, nanoneedles, nanowires, and nanobelts have been synthesized by thermal evaporation of pure ZnO micropowder. Based on the appearance of the as-synthesized products observed by field emission scanning electron microscope (FE-SEM), we show that substrate temperature and catalyst are the critical factors for the formation of different morphologies of ZnO nanostructures. The photoluminescence (PL) properties of the ZnO nanostructures were investigated. The difference in PL spectra both in intensity and structure for the different ZnO nanostructures are presented. We demonstrate that under appropriate synthesis conditions, highly crystallized and defect-free ZnO nano-structures can be obtained.
Some new properties of the Projection DC decomposition algorithm (we call it Algorithm A) and the... more Some new properties of the Projection DC decomposition algorithm (we call it Algorithm A) and the Proximal DC decomposition algorithm (we call it Algorithm B) Pham Dinh et al. in Optim Methods Softw, 23(4): 609-629 (2008) for solving the indefinite quadratic programming problem under linear constraints are proved in this paper. Among other things, we show that DCA sequences generated by Algorithm A converge to a locally unique solution if the initial points are taken from a neighborhood of it, and DCA sequences generated by either Algorithm A or Algorithm B are all bounded if a condition guaranteeing the solution existence of the given problem is satisfied.
... One of the main advocates of this new approach was John Underwood, who in 1984 proposed a ser... more ... One of the main advocates of this new approach was John Underwood, who in 1984 proposed a series of "Premises for 'Communicative' CALL" (Underwood, 1984, p. 52). Several types of CALL programs were developed and used during this the phase of communicative CALL. ...
The grafting of polymers and oligomers of ethylene oxide onto surfaces is widely used to prevent ... more The grafting of polymers and oligomers of ethylene oxide onto surfaces is widely used to prevent nonspecific adsorption of biological material on sensors and membrane surfaces. In this report, we show for the first time the robust covalent attachment of short oligoethylene oxide-terminated alkenes (CH(3)O(CH(2)CH(2)O)(3)(CH(2))(11)-(CH═CH(2)) [EO(3)] and CH(3)O(CH(2)CH(2)O)(6)(CH(2))(11)-(CH═CH(2)) [EO(6)]) from the reaction of alkenes onto silicon-rich silicon nitride surfaces at room temperature using UV light. Reflectometry is used to monitor in situ the nonspecific adsorption of bovine serum albumin (BSA) and fibrinogen (FIB) onto oligoethylene oxide coated silicon-rich silicon nitride surfaces (EO(n)-Si(x)N(4), x > 3) in comparison with plasma-oxidized silicon-rich silicon nitride surfaces (SiO(y)-Si(x)N(4)) and hexadecane-coated Si(x)N(4) surfaces (C(16)-Si(x)N(4)). A significant reduction in protein adsorption on EO(n)-Si(x)N(4) surfaces was achieved, adsorption onto EO(3)-Si(x)N(4) and EO(6)-Si(x)N(4) were 0.22 mg m(-2) and 0.08 mg m(-2), respectively. The performance of the obtained EO(3) and EO(6) layers is comparable to those of similar, highly protein-repellent monolayers formed on gold and silver surfaces. EO(6)-Si(x)N(4) surfaces prevented significantly the adsorption of BSA (0.08 mg m(-2)). Atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), X-ray reflectivity and static water contact angle measurements were employed to characterize the modified surfaces. In addition, the stability of EO(6)-Si(x)N(4) surfaces in phosphate-buffered saline solution (PBS) and alkaline condition (pH 10) was studied. Prolonged exposure of the surfaces to PBS solution for 1 week or alkaline condition for 2 h resulted in only minor degradation of the ethylene oxide moieties and no oxidation of the Si(x)N(4) substrates was observed. Highly stable antifouling coatings on Si(x)N(4) surfaces significantly broaden the application potential of silicon nitride-coated microdevices, and in particular of microfabricated filtration membranes.
Journal of Agricultural & Food Industrial Organization, 2020
This paper estimates the foodmiles (embedded distances) and transport-related carbon emissions of... more This paper estimates the foodmiles (embedded distances) and transport-related carbon emissions of 27 Food Quality Scheme (FQS) products – Protected Designation of Origin (PDO), Protected Geographical Indications (PGI) and organic – and their reference products. It goes further than the existing literature by adopting a value chain perspective, instead of the traditional consumer perspective, and focusing on FQS products. The same methodology is applied across all the case studies. The article specifically investigates the determinants of differences between FQS and their references. FQS products travel significantly shorter distances (−30%) and generate significantly lower transport-related emissions (−23%) than conventional food products. The differences are even greater for vegetal and organic products. The relationship between distance and transport-related emissions is not exactly proportional and highlights the importance of transport modes and logistics, in particular for expo...
Journal of Agricultural & Food Industrial Organization, 2020
We study the effect of a set of food quality scheme (FQS) products within the local economy using... more We study the effect of a set of food quality scheme (FQS) products within the local economy using a local multiplier approach based on LM3 methodology. To evaluate the effective contribution within the local area, we compare each FQS product with its equivalent standard/conventional counterpart. Local multiplier allows us to track the financial flows converging within the local area at the different levels of the supply chain so that we can measure the FQS product role in local economic activation. Overall, the FQS products exhibit a higher positive contribution to the local economy than the standard references. However, there is significant heterogeneity in the impact according to the product categories. In the case of vegetal products, the local economic advantage due to FQS is 7% higher than the reference products, but the statistical tests reject the null hypothesis that the medians are significantly different from zero. On the contrary, animal products exhibit a larger contribu...
Propranolol is one of the first medications of the beta-blocker used for antihypertensive drugs. ... more Propranolol is one of the first medications of the beta-blocker used for antihypertensive drugs. This study reports the facile route for the synthesis of propranolol and its novel derivatives. Herein, propranolol synthesis proceeded from 1-naphthol and isopropylamine under mild and less toxic conditions. Novel propranolol derivatives were designed by reactions of propranolol with benzoyl chloride, pyridinium chlorochromate, and n-butyl bromide through esterification, oxidation reduction, and alkylation, respectively. The isolation and purity of compounds were conducted using column chromatography and thin-layer chromatography. Mass spectrometry and 1H-NMR spectroscopy were applied to identify new compounds structure. Propranolol derivatives from 2-chlorobenzoyl chloride (compound 3), 2-fluorobenzoyl chloride (compound 5), and especially acetic anhydride (compound 6) manifested high yields and significantly increased water solubility. Six semisynthetic propranolol derivatives promise...
2012 34th International Conference on Software Engineering (ICSE), 2012
Code completion helps improve developers' programming productivity. However, the current support ... more Code completion helps improve developers' programming productivity. However, the current support for code completion is limited to context-free code templates or a single method call of the variable on focus. Using software libraries for development, developers often repeat API usages for certain tasks. Thus, a code completion tool could make use of API usage patterns. In this paper, we introduce GraPacc, a graphbased, pattern-oriented, context-sensitive code completion approach that is based on a database of such patterns. GraPacc represents and manages the API usage patterns of multiple variables, methods, and control structures via graph-based models. It extracts the context-sensitive features from the code under editing, e.g. the API elements on focus and their relations to other code elements. Those features are used to search and rank the patterns that are most fitted with the current code. When a pattern is selected, the current code will be completed via a novel graph-based code completion algorithm. Empirical evaluation on several real-world systems shows that GraPacc has a high level of accuracy in code completion.
2013 28th IEEE/ACM International Conference on Automated Software Engineering (ASE), 2013
ABSTRACT PHP is a dynamic language popularly used in Web development for writing server-side code... more ABSTRACT PHP is a dynamic language popularly used in Web development for writing server-side code to dynamically create multiple versions of client-side pages at run time for different configurations. A PHP program contains code to be executed or produced for multiple configurations/versions. That dynamism and multi-configuration nature leads to dangling references. Specifically, in the execution for a configuration, a reference to a variable or a call to a function is dangling if its corresponding declaration cannot be found. We conducted an exploratory study to confirm the existence of such dangling reference errors including dangling cross-language and embedded references in the client-side HTML/JavaScript code and in data-accessing SQL code that are embedded in scattered PHP code. Dangling references have caused run-time fatal failures and security vulnerabilities. We developed DRC, a static analysis method to detect such dangling references. DRC uses symbolic execution to collect PHP declarations/references and to approximate all versions of the generated output, and then extracts embedded declarations/references. It associates each detected declaration/reference with a conditional constraint that represents the execution paths (i.e. configurations/versions) containing that declaration/reference. It then validates references against declarations via a novel dangling reference detection algorithm. Our empirical evaluation shows that DRC detects dangling references with high accuracy. It revealed 83 yet undiscovered defects caused by dangling references.
Virtual machine (VM) migration has recently emerged as a potential tool to improve the performanc... more Virtual machine (VM) migration has recently emerged as a potential tool to improve the performance, cost and fault tolerance of data centers. However, migrating VMs requires more hardware resources to reserve target slots during the migration. A large number of simultaneous migrations can exhaust the physical resources of a data center. Consequently, the system may deny new service requests. In this paper, we introduce an efficient strategy to limit the number of target slots used for the migration process with the aim of maintaining high data center availability. In particular, the number of target slots is determined by the tradeoff between the waiting time of the queued migration processes and the probability that the system rejects new user requests due to the lack of available resources. We also propose a method to reduce the waiting time of the migration process by adding a sufficient number of slots during the migration process. Accordingly, a data center can use fewer resources while still guaranteeing the quality of the service. The efficiency of our proposed method is demonstrated by the experimental results.
ZnO nanostructures with different morphologies of nanorods, nanoneedles, nanowires, and nanobelts... more ZnO nanostructures with different morphologies of nanorods, nanoneedles, nanowires, and nanobelts have been synthesized by thermal evaporation of pure ZnO micropowder. Based on the appearance of the as-synthesized products observed by field emission scanning electron microscope (FE-SEM), we show that substrate temperature and catalyst are the critical factors for the formation of different morphologies of ZnO nanostructures. The photoluminescence (PL) properties of the ZnO nanostructures were investigated. The difference in PL spectra both in intensity and structure for the different ZnO nanostructures are presented. We demonstrate that under appropriate synthesis conditions, highly crystallized and defect-free ZnO nano-structures can be obtained.
Some new properties of the Projection DC decomposition algorithm (we call it Algorithm A) and the... more Some new properties of the Projection DC decomposition algorithm (we call it Algorithm A) and the Proximal DC decomposition algorithm (we call it Algorithm B) Pham Dinh et al. in Optim Methods Softw, 23(4): 609-629 (2008) for solving the indefinite quadratic programming problem under linear constraints are proved in this paper. Among other things, we show that DCA sequences generated by Algorithm A converge to a locally unique solution if the initial points are taken from a neighborhood of it, and DCA sequences generated by either Algorithm A or Algorithm B are all bounded if a condition guaranteeing the solution existence of the given problem is satisfied.
... One of the main advocates of this new approach was John Underwood, who in 1984 proposed a ser... more ... One of the main advocates of this new approach was John Underwood, who in 1984 proposed a series of "Premises for 'Communicative' CALL" (Underwood, 1984, p. 52). Several types of CALL programs were developed and used during this the phase of communicative CALL. ...
The grafting of polymers and oligomers of ethylene oxide onto surfaces is widely used to prevent ... more The grafting of polymers and oligomers of ethylene oxide onto surfaces is widely used to prevent nonspecific adsorption of biological material on sensors and membrane surfaces. In this report, we show for the first time the robust covalent attachment of short oligoethylene oxide-terminated alkenes (CH(3)O(CH(2)CH(2)O)(3)(CH(2))(11)-(CH═CH(2)) [EO(3)] and CH(3)O(CH(2)CH(2)O)(6)(CH(2))(11)-(CH═CH(2)) [EO(6)]) from the reaction of alkenes onto silicon-rich silicon nitride surfaces at room temperature using UV light. Reflectometry is used to monitor in situ the nonspecific adsorption of bovine serum albumin (BSA) and fibrinogen (FIB) onto oligoethylene oxide coated silicon-rich silicon nitride surfaces (EO(n)-Si(x)N(4), x > 3) in comparison with plasma-oxidized silicon-rich silicon nitride surfaces (SiO(y)-Si(x)N(4)) and hexadecane-coated Si(x)N(4) surfaces (C(16)-Si(x)N(4)). A significant reduction in protein adsorption on EO(n)-Si(x)N(4) surfaces was achieved, adsorption onto EO(3)-Si(x)N(4) and EO(6)-Si(x)N(4) were 0.22 mg m(-2) and 0.08 mg m(-2), respectively. The performance of the obtained EO(3) and EO(6) layers is comparable to those of similar, highly protein-repellent monolayers formed on gold and silver surfaces. EO(6)-Si(x)N(4) surfaces prevented significantly the adsorption of BSA (0.08 mg m(-2)). Atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), X-ray reflectivity and static water contact angle measurements were employed to characterize the modified surfaces. In addition, the stability of EO(6)-Si(x)N(4) surfaces in phosphate-buffered saline solution (PBS) and alkaline condition (pH 10) was studied. Prolonged exposure of the surfaces to PBS solution for 1 week or alkaline condition for 2 h resulted in only minor degradation of the ethylene oxide moieties and no oxidation of the Si(x)N(4) substrates was observed. Highly stable antifouling coatings on Si(x)N(4) surfaces significantly broaden the application potential of silicon nitride-coated microdevices, and in particular of microfabricated filtration membranes.
Journal of Agricultural & Food Industrial Organization, 2020
This paper estimates the foodmiles (embedded distances) and transport-related carbon emissions of... more This paper estimates the foodmiles (embedded distances) and transport-related carbon emissions of 27 Food Quality Scheme (FQS) products – Protected Designation of Origin (PDO), Protected Geographical Indications (PGI) and organic – and their reference products. It goes further than the existing literature by adopting a value chain perspective, instead of the traditional consumer perspective, and focusing on FQS products. The same methodology is applied across all the case studies. The article specifically investigates the determinants of differences between FQS and their references. FQS products travel significantly shorter distances (−30%) and generate significantly lower transport-related emissions (−23%) than conventional food products. The differences are even greater for vegetal and organic products. The relationship between distance and transport-related emissions is not exactly proportional and highlights the importance of transport modes and logistics, in particular for expo...
Journal of Agricultural & Food Industrial Organization, 2020
We study the effect of a set of food quality scheme (FQS) products within the local economy using... more We study the effect of a set of food quality scheme (FQS) products within the local economy using a local multiplier approach based on LM3 methodology. To evaluate the effective contribution within the local area, we compare each FQS product with its equivalent standard/conventional counterpart. Local multiplier allows us to track the financial flows converging within the local area at the different levels of the supply chain so that we can measure the FQS product role in local economic activation. Overall, the FQS products exhibit a higher positive contribution to the local economy than the standard references. However, there is significant heterogeneity in the impact according to the product categories. In the case of vegetal products, the local economic advantage due to FQS is 7% higher than the reference products, but the statistical tests reject the null hypothesis that the medians are significantly different from zero. On the contrary, animal products exhibit a larger contribu...
Propranolol is one of the first medications of the beta-blocker used for antihypertensive drugs. ... more Propranolol is one of the first medications of the beta-blocker used for antihypertensive drugs. This study reports the facile route for the synthesis of propranolol and its novel derivatives. Herein, propranolol synthesis proceeded from 1-naphthol and isopropylamine under mild and less toxic conditions. Novel propranolol derivatives were designed by reactions of propranolol with benzoyl chloride, pyridinium chlorochromate, and n-butyl bromide through esterification, oxidation reduction, and alkylation, respectively. The isolation and purity of compounds were conducted using column chromatography and thin-layer chromatography. Mass spectrometry and 1H-NMR spectroscopy were applied to identify new compounds structure. Propranolol derivatives from 2-chlorobenzoyl chloride (compound 3), 2-fluorobenzoyl chloride (compound 5), and especially acetic anhydride (compound 6) manifested high yields and significantly increased water solubility. Six semisynthetic propranolol derivatives promise...
2012 34th International Conference on Software Engineering (ICSE), 2012
Code completion helps improve developers' programming productivity. However, the current support ... more Code completion helps improve developers' programming productivity. However, the current support for code completion is limited to context-free code templates or a single method call of the variable on focus. Using software libraries for development, developers often repeat API usages for certain tasks. Thus, a code completion tool could make use of API usage patterns. In this paper, we introduce GraPacc, a graphbased, pattern-oriented, context-sensitive code completion approach that is based on a database of such patterns. GraPacc represents and manages the API usage patterns of multiple variables, methods, and control structures via graph-based models. It extracts the context-sensitive features from the code under editing, e.g. the API elements on focus and their relations to other code elements. Those features are used to search and rank the patterns that are most fitted with the current code. When a pattern is selected, the current code will be completed via a novel graph-based code completion algorithm. Empirical evaluation on several real-world systems shows that GraPacc has a high level of accuracy in code completion.
2013 28th IEEE/ACM International Conference on Automated Software Engineering (ASE), 2013
ABSTRACT PHP is a dynamic language popularly used in Web development for writing server-side code... more ABSTRACT PHP is a dynamic language popularly used in Web development for writing server-side code to dynamically create multiple versions of client-side pages at run time for different configurations. A PHP program contains code to be executed or produced for multiple configurations/versions. That dynamism and multi-configuration nature leads to dangling references. Specifically, in the execution for a configuration, a reference to a variable or a call to a function is dangling if its corresponding declaration cannot be found. We conducted an exploratory study to confirm the existence of such dangling reference errors including dangling cross-language and embedded references in the client-side HTML/JavaScript code and in data-accessing SQL code that are embedded in scattered PHP code. Dangling references have caused run-time fatal failures and security vulnerabilities. We developed DRC, a static analysis method to detect such dangling references. DRC uses symbolic execution to collect PHP declarations/references and to approximate all versions of the generated output, and then extracts embedded declarations/references. It associates each detected declaration/reference with a conditional constraint that represents the execution paths (i.e. configurations/versions) containing that declaration/reference. It then validates references against declarations via a novel dangling reference detection algorithm. Our empirical evaluation shows that DRC detects dangling references with high accuracy. It revealed 83 yet undiscovered defects caused by dangling references.
Virtual machine (VM) migration has recently emerged as a potential tool to improve the performanc... more Virtual machine (VM) migration has recently emerged as a potential tool to improve the performance, cost and fault tolerance of data centers. However, migrating VMs requires more hardware resources to reserve target slots during the migration. A large number of simultaneous migrations can exhaust the physical resources of a data center. Consequently, the system may deny new service requests. In this paper, we introduce an efficient strategy to limit the number of target slots used for the migration process with the aim of maintaining high data center availability. In particular, the number of target slots is determined by the tradeoff between the waiting time of the queued migration processes and the probability that the system rejects new user requests due to the lack of available resources. We also propose a method to reduce the waiting time of the migration process by adding a sufficient number of slots during the migration process. Accordingly, a data center can use fewer resources while still guaranteeing the quality of the service. The efficiency of our proposed method is demonstrated by the experimental results.
Uploads
Papers by An Nguyễn