Polymer-stabilized Transition Metal Nanocatalysts: Synthesis, Characterization, and Applications

Novel polymeric architectures and analytical methods were designed for the synthesis, characterization, and applications of metallic nanocatalysts. Four main research areas were investigated, namely: i) palladium nanocatalysts, ii) metal content analysis by a novel microplasma-based technique, iii) polyion complex micelle-metal hybrid structures, and iv) nickel nanocatalysts. The solution and solid-state properties of dendrigraft (arborescent) polystyrene-graft-poly(2-vinylpyridine) copolymers were studied by dynamic light scattering (DLS) and atomic force microscopy (AFM). The unimolecular micelles exhibited good colloidal stability and narrow size distributions in organic solvents, and a fried egg morphology when deposited onto mica substrates. The preparation of stable colloidal Pd nanoparticles within the dendritic templates was reported for the first time. The diameter of the nanoparticles varied from 0.7 to 3.4 nm depending on the loading level, reduction time, and arborescent copolymer generation used. The catalytic activity of the colloidal Pd nanoparticles was evaluated in the Suzuki-Miyaura (SM) cross-coupling reaction under green conditions. Good catalytic activity and a positive dendritic effect were evidenced, although air-sensitivity and flocculation limited the activity and recyclability of the catalysts. To determine the concentration of Pd in the copolymers, a novel microplasma-based technique was applied in organic solvents for the first time. Metal quantification by microplasma-optical emission spectrometry revealed stoichiometric complexation of the Pd salt by the pyridine groups, and kinetic aggregation studies highlighted the benefits of the polymer for colloidal stability. To obtain Pd nanoparticles dispersible in high water content solutions, polyion complex micelles were synthesized from arborescent copolymers and double-hydrophilic block copolymers. The latter, viz. poly(acrylic acid)-block-poly(2-hydroxyethyl acrylate), were obtained by hydrolysis of poly(tert-butyl acrylate)-block-poly(2-trimethylsilyloxyethyl acrylate), synthesized by atom transfer radical polymerization. The self-assembled complexes formed supramolecular aggregates with hydrodynamic diameters of 132 to 354 nm and narrow size distributions. The assemblies exhibited thermo-responsive properties in ethanol, dissociating above ca. 35 °C and reforming upon cooling. The polyion complexes, with hydrodynamic diameters ranging from 110 to 306 nm, were stable in water and were used for the solubilization of Pd nanocatalysts for aqueous Suzuki-Miyaura reactions. Lastly, the properties of nickel nanoparticles prepared at Vale-Inco by a novel thermal decomposition method were investigated. The specific surface area of the bare nanopowders ranged from 6.4 to 97.2 m2∙g-1, and their catalytic activity in the hydrogenation of adiponitrile and mesityl oxide was higher than for commercial catalysts in some cases. Treatment of the nanoparticles with diethylenetriamine further improved their catalytic activity. Polymeric stabilizers were designed to maximize the dispersibility and catalytic activity of the nanopowders. The structures investigated included triblock copolymers of polystyrene with poly(ethylene oxide) or poly(2-vinylpyridine), and telechelic poly(ethylene glycol). Application of the polymer-stabilized nickel catalysts in hydrogenation yielded up to 15-fold increases in specific catalytic activity as compared to the bare particles. The polymer was also effective at preventing oxidation by air under storage

Cambodia's Oil and Gas Activities and Future Outlooks

This article aims to reveal studies on Cambodia’s current activities in the oil and gas industry. The paper will be divided into three parts: 1) Distribution of oil and gas resources 2) Current Operations in the oil and gas industry and 3) Conclusion and discussion of the future of the industry

Antibacterial Porous Polymeric Monolith Columns with Amphiphilic and Polycationic Character on Cross-linked PMMA Substrates for Cell Lysis Applications

The application of porous polymeric monolith (PPM) columns as an effective tool for bacterial cell lysi within microfluidic chips is demonstrated. By taking advantage of the large surface area and controllable pore size inherent to PPMs, we developed a double mechanism cell lysis technique. The bacterial cell wall is mechanically sheared by flowing through the porous medium of the PPM column, but it is also damaged and disintegrated by physical contact with the antibacterial polymeric biocide covering the porous surface. This leads to leakage of the intracellular contents. The stable and nonleaching antibacterial column introduced in this work alleviates the need for chemical or enzymatic lysins and their potential release of polymerase chain reaction (PCR) inhibitors. The PPM columns were obtained by the photoinitiated free radical co polymerization of n-butyl methacrylate (BuMA) and N-(tert butyloxycarbonyl)aminoethyl methacrylate (Boc-AEMA) in the presence of a cross-linker and porogenic solvents. The porous network was synthesized directly inside a microfluidic channel fabricated in a cross-linked poly(methyl methacrylate) (X-PMMA) substrate by laser micromachining. After removing the Boc protecting group with phosphoric acid, an amphiphilic and cationic network structure reminiscent of synthetic mimics of antimicrobial peptides (SMAMPs) was obtained. The antibacterial activity of the PPM columns was tested against Bacillus subtilis (B. subtilis) and Escherichia coli (E. coli) cells. Cell lysis was evidenced by DNA release, which was then amplified by PCR and confirmed by gel electrophoresis, to verify that the antibacterial monolithic columns did not strongly interfere with the PCR process

Facteurs agro-environnementaux associés à la résistance antimicrobienne d'Escherichia coli dans l'eau potable des puits du sud de l'Ontario

Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal

Microencapsulation by in situ polymerization of amino resins

By surrounding small droplets with a coating, one can obtain micrometer-size capsules (microcapsules), and combine multiple properties into a single system. This technology has allowed the design of advanced and functional materials. Amino resins are composed principally of urea and/or melamine and formaldehyde, and exhibit advantages as wall-forming materials, such as high mechanical strength and chemical resistance. In this review, a general description of the encapsulation process by in situ polymerization of amino resins is given. Characterization methods, and the influence of the physical and design parameters are discussed. A mechanistic description, and some of the promising avenues of research are also presented

GUARD study report: Good Use of Antimalarials and Rapid Diagnostic Tests in Cambodia study report

Using a mixed methods approach that included quality assessments, a mystery client study and qualitative research, we conducted a comprehensive evaluation of malaria Rapid Diagnostic Tests and in the private sector in 12 health centre catchment areas across Cambodia. In summary, we found that the RDTs collected from drug shops had maintained good quality and that storage and transport conditions were on the whole satisfactory. Uptake of RDTs appeared to highest in the most highly trained providers i.e. “cabinets”, and lowest in grocery shops, with pharmacies and drugs shops having some ambiguity around their role. Findings from the focus group discussions and the mystery client study suggest that some of the problems in uptake and interpretation relate to RDTs being on the margins of practice for these providers who see themselves as either providing a diagnosis and cure (pinit pchier bal) or simply selling drugs for symptomatic relief (lout tnam). Several problems with RDTs were identified in terms of their actual use, in particular relating to interpretation of results, blood safety, and problems related to the buffer and the blood collecting device. In summary this study provides a comprehensive assessment of malaria RDTs in one of the first countries to implement them in the private sector

Effects of Microbial Quorum Sensing on Membrane Fouling and Characteristics of Extracellular Polymeric Substances in a Membrane Bioreactor Process

13301甲第4742号博士（工学）金沢大学博士論文要旨Abstract 要約Outline 掲載予定あり 共著者：Phuc-Nguon Hong; Ryo Hoda; Ryoko Ikemoto; Mana Noguchi, Norihisa Matsuur

Effects of Microbial Quorum Sensing on Membrane Fouling and Characteristics of Extracellular Polymeric Substances in a Membrane Bioreactor Process

13301甲第4742号博士（工学）金沢大学博士論文本文Full 掲載予定あり 共著者：Phuc-Nguon Hong; Ryo Hoda; Ryoko Ikemoto; Mana Noguchi, Norihisa Matsuur

Assessing the quality of service of village malaria workers to strengthen community-based malaria control in Cambodia

BackgroundMalaria continues to be a major public health problem in remote forested areas in Cambodia. As a national strategy to strengthen community-based malaria control, the Cambodian government has been running the Village Malaria Worker (VMW) project since 2001. This study sought to examine the nature and quality of the VMWs\u27 services.MethodsData collection was carried out in February and March 2008 through interviews with one of the two VMWs who takes the lead in malaria control activities in each of the 315 VMW villages (n = 251). The questionnaire addressed 1) the sociodemographic characteristics of VMWs, 2) service quality, 3) actions for malaria prevention and vector control, and 4) knowledge of malaria epidemiology and vector ecology.ResultsVMWs were effective in conducting diagnosis with Rapid Diagnostic Tests (RDTs) and prescribing anti-malarials to those who had positive RDT results, skills that they had acquired through their training programmes. However, most other services, such as active detection, explanations about compliance, and follow-up of patients, were carried out by only a small proportion of VMWs. The variety of actions that VMWs took for malaria prevention and vector control was small (average action index score 12.8/23), and their knowledge was very limited with less than 20% of the VMWs giving correct answers to six out of seven questions on malaria epidemiology and vector ecology. Knowledge of vector breeding places and malaria transmission were significant determinants of both the quality of VMWs\u27 services and the variety of their actions for malaria prevention and vector control.ConclusionsVMWs\u27 services focused primarily on diagnosis and treatment. Their focus needs to be broadened to cover other aspects of malaria control in order to further strengthen community-based malaria control. VMWs\u27 actions and knowledge also need substantial improvement. Strengthening training programmes can help achieve better performance by VMWs