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Aluminium phosphide (ALP) and aluminium zinc phosphide (ZnP), the two main ingredients of fumigation drugs, are commonly used to kill insects or rodents in grain. When exposed to water, highly toxic phosphine gas is released and absorbed through the respiratory or digestive tract. Phosphine gas could non-selectively block cytochrome oxidase, inhibit electron transfer and suppress oxidative phosphorylation, leading to cellular hypoxia and organ dysfunction. The characteristic clinical manifestations are refractory shock and metabolic acidosis with high mortality. However, patients with ALP poisoning have a chance to be cured. Here, we report a case of oral ALP poisoning that was successfully treated by extracorporeal membrane oxygenation (ECMO) combined with continuous renal replacement therapy (CRRT) during frequent ventricular fibrillation and cardiac dysfunction.

Las lecciones de Chino paso a paso II permiten al estudiante aprender y ejercitar el chino mandarín. Gracias a ejercicios especiales podrá practicar la lectura de ensayos, la escritura de los distintos caracteres y la escucha y comprensión gracias a canciones y poemas que permiten experimentar el ritmo del idioma. Los dos libros que componen Chino paso a paso II facilitan el aprendizaje de las habilidades exigidas en el examen internacional de chino mandarín HSK. Esta es la continuación del libro de texto Chino paso a paso I, que en el 2010 ganó el premio a la excelencia en la categoría de material internacional de enseñanza del chino mandarín, por Hanban, la Oficina Central del Instituto Confucio (institución que promueve la enseñanza del chino, con sede en Beijing). Huijing Zhang y Mingjun Yuan

Antibiotic resistance threatens effective treatment of microbial infections globally. This situation has spurred the hunt for new antimicrobial compounds in both academia and the pharmaceutical industry. Here, we report how the widely used antitumor drug cisplatin may be repurposed as an effective antimicrobial against the nosocomial pathogen Pseudomonas aeruginosa. Cisplatin was found to effectively kill strains of P. aeruginosa. In such experiments, transcriptomic profiling showed upregulation of the recA gene, which is known to be important for DNA repair, implicating that cisplatin could interfere with DNA replication in P. aeruginosa. Cisplatin treatment significantly repressed the type III secretion system (T3SS), which is important for the secretion of exotoxins. Furthermore, cisplatin was also demonstrated to eradicate in vitro biofilms and in vivo biofilms in a murine keratitis model. This showed that cisplatin could be effectively used to eradicate biofilm infections which were otherwise difficult to be treated by conventional antibiotics. Although cisplatin is highly toxic for humans upon systemic exposure, a low toxicity was demonstrated with topical treatment. This indicated that higher-than-minimal inhibitory concentration (MIC) doses of cisplatin could be topically applied to treat persistent and recalcitrant P. aeruginosa infections.

In this study,an implantable optrode was developed for optogenetics stimulation of neural population in nuclei or multi-sites in neural circuits.The optrode was composed of base layer,micro-light emitting diode(LED)and coating layer.The base layer was a 150μm thick polyimide substrate on which copper wires and contacts were fabricated by flexible printed circuit board processes.The micro-LED was soldered on the contacts using SnBi.ParyleneC was deposited over the optrode as the coating layer using a vacuum vapor deposition system.The optical output power was tested by optical power meter and the insulating property was tested using saline in the experiment.The stimulation function of the optrode was demonstrated through animal experiment.The width of the optrode was500μm and the maximum thickness of the optrode was 310μm at the LED position.The thickness of the parylene coating layer was about 1μm.The maximum optical output power of optrode was 9.31 mW and the effective illumination area was a 3.03mm2 spherical cap at 650μm deep in brain tissue.The optrode was still functional after 14 days in physiological saline.Conventional copper electrodes were used to verify the efficacy of the optrode for stimulation and robust spiking activities of the expressing Channelrhodopsin-2neurons in the entire cortex of a mouce were recorded.Obvious behavior change happened when light stimulation was applied to the expressing Channelrhodopsin-2neurons in the secondary motor cortex of the mice.The optrode has the characteristics of large effective illumination range,flexible in implantation and long-term implantable,which provide neural population in nuclei research a new tool.

Summary The nucleotide signalling molecule bis-(3'-5’)-cyclic dimeric guanosine monophosphate (c-di-GMP) plays an essential role in regulating microbial virulence and biofilm formation. C-di-GMP is synthesized by diguanylate cyclase (DGC) enzymes and degraded by phosphodiesterase (PDE) enzymes. One intrinsic feature of c-di-GMP signalling is the abundance of DGCs and PDEs encoded by many bacterial species. It is unclear whether the different DGCs or PDEs coordinately establish the c-di-GMP regulation or function independently of each other. Here, we provide evidence that multiple DGCs are involved in regulation of c-di-GMP on synthesis of the major iron siderophore pyoverdine in Pseudomonas aeruginosa. Constitutive expression of the WspG or YedQ DGC in P. aeruginosa is able to induce its pyoverdine synthesis. Induction of pyoverdine synthesis by high intracellular c-di-GMP depends on the synthesis of exopolysaccharides and another two DGCs, SiaD and SadC. SiaD was found to boost the c-di-GMP synthesis together with constitutively expressing YedQ. The exopolysaccharides and the SiaD DGC were found to modulate the expression of the RsmY/RsmZ ncRNAs. Induction of the RsmY/RsmZ ncRNAs might enhance the pyoverdine synthesis through SadC. Our study sheds light on a novel multiple DGC-coordinated c-di-GMP regulatory mechanism of bacteria.

Since its discovery 22 years ago, the bacterial cell-to-cell communication system, termed quorum sensing (QS), has shown potential as antipathogenic target. Previous studies reported that ajoene from garlic inhibits QS in opportunistic human pathogen Pseudomonas aeruginosa. In this study, screening of an in-house compound library revealed two sulfur-containing compounds which possess structural resemblance with ajoene and inhibit QS in bioreporter assay. Following a quantitative structure–activity relationship (SAR) study, 25 disulfide bond-containing analogues were synthesized and tested for QS inhibition activities. SAR study indicated that the allyl group could be replaced with other substituents, with the most active being benzothiazole derivative (IC50 = 0.56 μM). The compounds were able to reduce QS-regulated virulence factors (elastase, rhamnolipid, and pyocyanin) and successfully inhibit P. aeruginosa infection in murine model of implant-associated infection. Altogether, the QS inhibition activity of the synthesized compounds is encouraging for further exploration of novel analogues in antimicrobial drug development. MOE (Min. of Education, S’pore) NRF (Natl Research Foundation, S’pore)

This work pertains to visualizing a transport model for adsorption of surfactants from micelle solutions onto a clean air/water interface. Under the condition of surfactant adsorption from very dilute solutions, the time scale for diffusion of a surfactant monomer is much slower than the time scale for kinetic breakdown of the aggregates. A theoretical model predicts two regimes for the adsorption dynamics. We visualize these two regimes under the mechanism of solubilization using fluorescence microscopy, in which an insoluble fluorescent probe, NBD-HAD (4-(hexadecylamino)-7-nitrobenz-2-oxa-1,3-diazole), is used to illuminate the micelles. The dye fluoresces in the microenvironment of micelles but is quenched in the aqueous solution on laser excitation. The region containing micelles is illuminated, but the region which does not contain micelles appears dark. For surfactant solution of C14E6 at concentration just above the critical micelle concentration (CCMC), CCMC = 4.4 mg/L, a dark region between the bright image of the air/water interface and the micelle-containing zone is observed. This dark region becomes smaller with time and finally disappears once equilibrium is reached. For a surfactant solution of C14E6 at the concentration of 4.74CCMC, which is higher than a critical total surfactant concentration ( C T c ) of 4.25CCMC, we observe bright images through surfactant solutions during the adsorption process. Fluorescence images validate the theoretical model.

Cyano-functionalized allylic phosphine substrates containing the ortho-metalated (R)-(1-(dimethylamino)ethyl)naphthalene as the chiral auxiliary were synthesized from bromoacetaldehyde dimethylacetal via a one-pot process. The diastereoselective hydrophosphination reactions of the cis- and trans-allylic phosphine substrates gave the cyano-functionalized chiral 1,2-bis(diphenylphosphino)ethane products with high yield and stereoselectivity. The subsequent organic transformation reactions of the cyano-substituted products chemoselectively afforded the formyl- and hydroxyl-functionalized chiral 1,2-diphosphine complexes with retention of stereochemistry. The coordination properties and absolute configurations of the novel 1,2-diphosphine complexes were established by single crystal X-ray crystallography. The optically pure 1,2-bis(diphenylphosphino)ethane ligands with cyano-, formyl- and hydroxyl-functionalities could be liberated in high yields from the corresponding dihalo palladium complexes by treatment with aqueous potassium cyanide.

A novel cyano-functionalized monophosphine palladium substrate containing the ortho-metalated (R)-(1-(dimethylamino)ethyl)naphthalene as the chiral auxiliary was synthesized from 3-chloropropionaldehyde diethylacetal via a one-pot process. The asymmetric hydrophosphination reactions between diphenylphosphine and the trans- or cis-monophosphine substrates were carried out under mild conditions, which gave the corresponding cyano-substituted chiral 1,3-bis(diphenylphosphino)propane palladium complexes with good yields and stereoselectivities. Subsequent functional group transformation reactions were conducted by successive treatment of the hydrophosphination products with Dibal-H and chemoselectively yielded the formyl- and hydroxyl-functionalized chiral 1,3-diphosphine complexes. The absolute configurations and coordination information of the novel 1,3-diphosphine complexes were analyzed by X-ray crystallography. The optically pure 1,3-bis(diphenylphosphino)propane ligands with cyano, formyl, and hydroxyl ...

Organopalladium complexes containing ortho-metalated (R)-(1-(dimethylamino)ethyl)naphthalene and (R)-[1-(1-(dimethylamino)-2,2-dimethylpropyl]-2,5-dimethylbenzene as the chiral auxiliaries were used to promote the asymmetric hydrophosphination reactions between diphenylphosphine and ester- and keto-functionalized allenes in high regio- and stereoselectivites under mild conditions. The hydrophosphination reactions generated the 1,2-diphosphine ligands with chirality residing on the carbon backbone as bidentate chelates on the chiral organopalladium templates. The major isomers were isolated in appreciable yields in configurationally pure forms and characterized by means of single-crystal X-ray crystallography. The chiral auxiliaries could be removed chemoseletively by treatment with concentrated hydrochloric acid to form the corresponding optically pure neutral dichloro complexes. Subsequently, the dichloro complexes underwent ligand displacement with aqueous cyanide to generate their corresponding optical...

The organopalladium complex containing ortho-metalated (S)-[1-(dimethylamino)ethyl]naphthalene as the chiral auxiliary has been used successfully to promote the asymmetric cycloaddition reaction between 3,4-dimethyl-1-phenylarsole and diphenylvinylphosphine oxide in high stereoselectivity (only one isomer). However, the neutral dichloro palladium complex obtained upon removal of the auxiliary is very unstable and instantly decomposed to produce the arsenic elimination reaction product (3,4-dimethyl-2,4-cyclohexadienyl)diphenylphosphine oxide. However when the same reaction was promoted by the analogous platinum complex, only one stereoisomer was again obtained, but the resulting dichloro platinum complex is very stable in the solid state as well as in solution and coordinates to the platinum center as a As−O bidentate ligand, as confirmed by 1H NMR and single-crystal X-ray analysis. The enantiomerically pure As P═O hetero-bidentate ligand could be readily liberated from the dichloro platinum complex as a...

The organopalladium complex containing ortho-metalated (R)-(1-(dimethylamino)ethyl)naphthalene as the chiral auxiliary has been used to promote the asymmetric hydrophosphination reactions of diphenylphosphine with (E)-1-phenyl-3-pyridin-2-yl-2-propenone and (E)-1-methyl-3-pyridin-2-yl-2- propenoate in high regio- and stereoselectivities under mild conditions. Hydrophosphination of (E)-1-phenyl-3-pyridin-2-yl-2-propenone with diphenylphosphine generated two stereoisomeric products in a ratio of 8:1 as five-membered 2-pyridylphosphine P−N bidentate chelates on the chiral naphthylamine palladium template. Using the same chiral metal template, the corresponding hydrophosphination reaction of (E)-1-methyl-3-pyridin-2-yl-2-propenoate gave only one product as a six-membered P−N bidentate chelate. The naphthylamine auxiliary could be removed chemoselectively from the template product by treatment with concentrated hydrochloric acid to form the corresponding optically pure neutral complexes. Subsequent ligand disp...

Ester- and keto-functionalized allylic monophosphine palladium complexes containing ortho-metalated (R)-(1-(dimethylamino)ethyl)naphthalene as the chiral auxiliary were synthesized via a versatile one-pot process. Subsequent asymmetric hydrophosphination of the coordinated allylic substrates promoted by the chiral auxiliary gave the corresponding functionalized chiral 1,2-bis(diphenylphosphino)ethane ligands in high yields under mild conditions. The coordination properties and absolute configurations of the resultant diphosphine ligands were established by single-crystal X-ray crystallography. The coordinated 1,2-diphosphine ligands could be subsequently liberated stereospecifically to yield enantiomerically pure functionalized diphosphines in high yields.

The (1,1)- and (1,2)-addition of diphenylphosphine to 3-butyn-2-one and ethyl propiolate can be controlled chemoselectively by regulating the amount of triethylamine as the external base and in the presence of the chiral organopalladium(II) template derived from (R)-N,N-dimethyl-1-(1-naphthyl)ethylamine.

Three different types of characteristic structures-microcells, nanoclay, and crystallite lamella-exist in injection molded polyamide-6 microcellular nanocomposites. These structures are in completely different scales. The spatial orientation of these microscale structures crucially determines the material's bulk properties. Based on scanning electron microscopy, transmission electron microscopy, and two-dimensional X-ray diffractometry measurements, it was found that the nanoclay and the crystallite formed special geometric structures around the microcells and near the part skins. The nanoclay platelets lay almost parallel to the surfaces of the molded parts. Preferred orientation of the crystallites was induced by the presence of the nanoclay. A molecular-based model is proposed to describe the structural hierarchy and correlations among the microcells, nanoclay, and crystallite lamella. From the small-angle X-ray scattering experiments, it was found that microcellular injection molding produces relatively smaller crystallite lamella than that of conventional injection molding, and that for both solid and microcellular neat resin parts the crystallite lamella thickness at the part skin is smaller than that at the core. Polarized optical microscopy results also indicated that the size of crystallites in the microcellular neat resin and nanocomposite parts is smaller than that in the corresponding solid parts. POLYM. ENG. SCI., 47:765–779, 2007. © 2007 Society of Plastics Engineers

Bis-(3′-5′)-cyclic dimeric guanosine monophosphate (c-di-GMP) is a global secondary bacterial messenger that controls the formation of drug-resistant multicellular biofilms. Lowering the intracellular c-di-GMP content can disperse biofilms, and it is proposed as a biofilm eradication strategy. However, freshly dispersed biofilm cells exhibit a physiology distinct from biofilm and planktonic cells, and they might have a clinically relevant role in infections. Here we present in vitro and in vivo protocols for the generation and characterization of dispersed cells from Pseudomonas aeruginosa biofilms by reducing the intracellular c-di-GMP content through modulation of phosphodiesterases (PDEs). Unlike conventional protocols that demonstrate biofilm dispersal by biomass quantification, our protocols enable physiological characterization of the dispersed cells. Biomarkers of dispersed cells are identified and quantified, serving as potential targets for treating the dispersed cells. The in vitro protocol can be completed within 4 d, whereas the in vivo protocol requires 7 d. NRF (Natl Research Foundation, S’pore) MOE (Min. of Education, S’pore) Accepted version

Stress response plays an important role on microbial adaptation under hostile environmental conditions. It is generally unclear how the signaling transduction pathway mediates a stress response in planktonic and biofilm modes of microbial communities simultaneously. Here, we showed that metalloid tellurite (TeO32–) exposure induced the intracellular content of the secondary messenger cyclic di-GMP (c-di-GMP) of Pseudomonas aeruginosa. Two diguanylate cyclases (DGCs), SadC and SiaD, were responsible for the increased intracellular content of c-di-GMP. Enhanced c-di-GMP levels by TeO32– further increased P. aeruginosa biofilm formation and resistance to TeO32–. P. aeruginosa ΔsadCΔsiaD and PAO1/plac-yhjH mutants with low intracellular c-di-GMP content were more sensitive to TeO32– exposure and had low relative fitness compared to the wild-type PAO1 planktonic and biofilm cultures exposed to TeO32–. Our study provided evidence that c-di-GMP level can play an important role in mediating stress response in microbial communities during both planktonic and biofilm modes of growth.

This article presents the effects of nanoclay and supercritical nitrogen on the crystallization and thermal behavior of microcellular injection-molded polyamide-6 (PA6) nanocomposites with 5 and 7.5 wt% nanoclay. Differential scanning calorimetry (DSC), X-ray diffractometry (XRD), and polarized optical microscopy (POM) were used to characterize the thermal behavior and crystalline structure. The isothermal and nonisothermal crystallization kinetics of neat resin and its corresponding nanocomposite samples were analyzed using the Avrami and Ozawa equations, respectively. The activation energies determined using the Arrhenius equation for isothermal crystallization and the Kissinger equation for nonisothermal crystallization were comparable. The specimen thickness had a significant influence on the nonisothermal crystallization especially at high scanning rates. Nanocomposites with an optimal amount of nanoclay possessed the highest crystallization rate and a higher level of nucleation activity. The nanoclay increased the magnitude of the activation energy but decreased the overall crystallinity. The dissolved SCF did not alter the crystalline structure significantly. In contrast with conventionally injection-molded solid counterparts, microcellular neat resin parts and microcellular nanocomposite parts were found to have lower crystallinity in the core and higher crystallinity near the skin.

The microstructure and mechanical properties of microcellular injection molded polyamide-6 (PA6) nanocomposites were studied. Cell wall structure and smoothness were determined by the size of the crystalline structure, which, in turn, were based on the material system and molding conditions. The correlation between cell density and cell size of the materials studied followed an exponential relationship. Supercritical fluid (SCF) facilitated the intercalation and exfoliation of nanoclays in the microcellular injection molding process. The orientation of nanoclays near the surface of microcells and between microcells was examined and a preferential orientation around the microcells was observed. Nanoclays in the microcellular injection molding process promoted the γ-form and suppressed the α-form crystalline structure of PA6. Both nanoclays and SCF lowered the crystallinity of the parts. Microcells improved the normalized toughness of the nanocomposites. Both microcells and nanoclay had a significant influence on the mechanical properties of parts depending on the molding conditions.

This paper reviews some of the recent developments of microcellular injection molding, which is capable of producing parts with excellent dimensional stability using lower injection pressure, shorter cycle time, and less material. Process conditions as well as nano/micro-fillers such as nanoclay and core–shell rubber have a strong influence on cell density and cell size, hence, the final material properties of the molded parts. The addition of nano/micro-fillers at optimum loading levels can generally facilitate the formation of microcellular plastics with higher cell density and smaller cell size leading to superior mechanical properties. The novel integration of a solid plastic surface with a microcellular plastic core via the co-injection molding technique has been investigated to achieve Class “A” surfaces and improved material performance. An improved mathematical model has been developed to simulate the cell growth behavior in the microcellular injection molding process.

The effects of submicron core-shell rubber (CSR) particles, nanoclay fillers, and molding parameters on the mechanical properties and cell structure of injection-molded microcellular polyamide-6 (PA6) composites were studied. The experimental results of PA6 nanocomposites with 5.0 and 7.5 wt% nanoclay loadings and of CSR-modified PA6 composites with 0.5 and 3.1 wt% CSR loadings were compared to their neat resin counterparts. This study found that nanoclay was more efficient in promoting a smaller cell size, larger cell density, and higher tensile strength for microcellular injection molding parts. A higher nanoclay loading led to more brittle behavior for microcellular parts. It was found that a proper amount of CSR particles could be added to the microcellular injection-molded PA6 to reduce the cell size, increase the cell density, and enhance the toughness of the molded part. However, CSR particles were less effective cell nucleation agents as compared to nanoclay for producing desirable cell structures, and a higher CSR loading was found to have diminishing effects on the process and on the properties of the parts. POLYM. ENG. SCI., 45:773–788, 2005. © 2005 Society of Plastics Engineers

This paper presents the effects of processing parameters and submicron core-shell rubber particle filler on the mechanical properties and cell morphology of microcellular injection molded polyamide-6 (PA-6) composites. Three types of materials are studied, namely, neat PA-6 resin, and 0.5 wt% and 3.1 wt% core-shell rubber polybutylacrylate-polymethylmethacrylate-filled PA-6 composites. This study shows that the addition of a small amount (0.5%) of core-shell rubber particles improved the ductility and impact strength of micro-cellular injection molded PA-6 samples. In comparison to the microcellular injection molded PA-6 polymer-clay nanocomposite, the samples with a small amount (0.5%) of core-shell rubber had much higher impact strength and ductility. The small addition of core-shell rubber also reduced cell size and increased cell density of the microcellular injection molded PA-6 parts, in comparison to their neat resin counterparts. On the other hand, at higher core-shell rubber loading, the cell size and density were found to be similar to that of the neat resin.

The crystallization behaviors of polyamide-6 (PA-6) and its nanocomposites undergoing the microcellular injection molding process are studied using Transmission Electron Microscopy (TEM), X-ray Diffractometer (XRD), Polarized Optical Microscopy (POM), and Differential Scanning Calorimetry (DSC). The relationships among the morphology, the mechanical property of the molded parts, and the crystallization behavior are investigated. With the addition of nanoclays in microcellular injection molded parts, the growth of the γ-form crystal is suppressed and the formation of γ-form crystals is promoted. Both nanoclay and dissolved gas have a big influence on PA-6 crystalline structures. The existence of nanoclay increases the initial crystallization rate. But with extra addition of nanoclays in the polymer matrix, the increase of crystallization rate is reduced. Microcellular injection molded nanocomposites with proper amount of nanoclays possess the maximum crystallization activation energy and produce a finer and denser microcell structure which leads to better mechanical properties.

This study aims to explore the processing benefits and property improvements of combining nanocomposites with microcellular injection molding. The microcellular nanocomposite processing was performed on an injection-molding machine equipped with a commercially available supercritical fluid (SCF) system. The molded samples produced based on the Design of Experiments (DOE) matrices were subjected to tensile testing, impact testing, Dynamic Mechanical Analysis (DMA), and Scanning Electron Microscope (SEM) analyses. Molding conditions and nano-clays have been found to have profound effects on the cell structures and mechanical properties of polyamide-6 (PA-6) base resin and nanocomposite samples. The results show that microcellular nanocomposite samples exhibit smaller cell size and uniform cell distribution as well as higher tensile strength compared to the corresponding base PA-6 microcellular samples. Among the molding parameters studied, shot size has the most significant effect on cell size, cell density, and tensile strength. Fractographic study reveals evidence of different modes of failure and different regions of fractured structure depending on the molding conditions. Polym. Eng. Sci. 44:673–686, 2004. © 2004 Society of Plastics Engineers.

The effects of adding nanoclay to polyamide-6 (PA-6) neat resin, and the effects of processing parameters on cell density and size in microcellular injection-molded components were investigated. In addition, the crystal sizes, structures, and orientation were analyzed with the use of x-ray diffraction (XRD) and a polarized optical microscope. The standard ASTM D 638-02 tensile bars for the analyses were molded according to a fractional four-factor, three-level, L9 Taguchi design of experiment (DOE) with varying melt temperature, injection speed, supercritical fluid (SCF) concentration, and shot size. It was found that the presence of montmorillonite (MMT) nanoclay greatly reduced the size of the cells and crystals, but increased their density in comparison with neat resin processed under identical molding conditions. In addition, at the sprue section downstream of the machine nozzle, cell size gradually decreased from the part center toward the skin for both the neat resin and the nanocomposite. It was also found that shot size was the most important processing parameter for both the neat resin and nanocomposite in affecting cell density and size in microcellular injection molding components. Weakly preferred crystal orientations were observed on the surface of microcellular injection-molded PA-6/MMT tensile bars. Finally, the addition of nanoclay in PA-6 neat resin facilitated the formation of γ-phase crystals in the molded components. Polym. Eng. Sci. 45:52–61, 2005. © 2004 Society of Plastics Engineers.

This paper presents the effects of process conditions and nano-clay fillers on the microstructure (namely, size, density, and distribution of microcells within samples) and the resulting mechanical properties of microcellular injection molded polyamide-6 (PA-6) nanocomposite and its neat-resin counterpart. Based on the design of experiments (DOE) matrices, samples were molded at various supercritical fluid (SCF) levels, melt temperatures, shot sizes, melt plastication pressures (MPP), and injection speeds. These samples were then subjected to scanning electron microscope (SEM) analysis, tensile testing, and impact testing. For both materials, the microstructure and the mechanical properties of the molded samples were found to be dependent on the process conditions and presence of nano-clay, which could serve as microcell nucleating agent. At higher weight reductions, the nanocomposite samples exhibit much smaller microcells and higher cell densities than those obtained in the neat-resin samples. The SEM micrographs reveal noticeable differences in microcell surface roughness between the nanocomposite and the neat resin. A statistical design analysis was used to identify the optimal process conditions that would result in desirable cell size and density and, thus, better mechanical properties. For example, the highest tensile strengths have been observed at the highest levels of shot size, MPP, injection speed, and SCF level, and at the lowest level of melt temperature.

The nucleotide signalling molecule bis-(3'-5')-cyclic dimeric guanosine monophosphate (c-di-GMP) plays an essential role in regulating microbial virulence and biofilm formation. C-di-GMP is synthesized by diguanylate cyclase (DGC) enzymes and degraded by phosphodiesterase (PDE) enzymes. One intrinsic feature of c-di-GMP signalling is the abundance of DGCs and PDEs encoded by many bacterial species. It is unclear whether the different DGCs or PDEs coordinately establish the c-di-GMP regulation or function independently of each other. Here, we provide evidence that multiple DGCs are involved in regulation of c-di-GMP on synthesis of the major iron siderophore pyoverdine in Pseudomonas aeruginosa. Constitutive expression of the WspG or YedQ DGC in P. aeruginosa is able to induce its pyoverdine synthesis. Induction of pyoverdine synthesis by high intracellular c-di-GMP depends on the synthesis of exopolysaccharides and another two DGCs, SiaD and SadC. SiaD was found to boost the c-di-GMP synthesis together with constitutively expressing YedQ. The exopolysaccharides and the SiaD DGC were found to modulate the expression of the RsmY/RsmZ ncRNAs. Induction of the RsmY/RsmZ ncRNAs might enhance the pyoverdine synthesis through SadC. Our study sheds light on a novel multiple DGC-coordinated c-di-GMP regulatory mechanism of bacteria.

For the restructured electric power industry, transmission planning had become increasingly complicated with both economic and engineering considerations, and many new issues have surfaced. Significant challenges arising from the reconstruction for transmission planner are extensively analyzed from the views of transmission, generation, uncertainties, regulatory risks, and market needs, etc in this paper. Then, a specific long term transmission development plan for restructured electric power industry in Philippines is introduced. Long term transmission development plan of Philippines covers 2010 to 2030. For Luzon Grid, the long term transmission plan mainly focuses on the 500 kV and major 230kV transmission backbone, which is the major highway for bulk power transmission and the Metro Manila transmission configuration that serves the grid's load center. For Visayas grid, the plan mainly focuses on the 230kV transmission backbone from Samar, Leyte, Cebu, Negro, and Panay Island, which is almost 900 km. For Mindanao grid, it focuses on upgrading transmission backbone from north part to the south part from 138kV to 230kV and on improving its transmission capacity.

This thesis describes the asymmetric synthesis of functionalized chiral diphosphines via enantiomeric organopalladium complex (R-26) promoted asymmetric hydrophosphination and Diels-Alder reactions. Introduction of functionalities on chiral diphosphines using organic transformations with palladium template as protection is also demonstrated. In Chapter 1, a brief introduction on the synthesis and application of chiral diphosphines, research development in our research group and the aims of this project is presented. In Chapter 2, the ester- and keto-functionalized allylic monophosphine palladium complexes containing the ortho-metalated (R)-(1-(dimethylamino)ethyl)naphthalene as the chiral auxiliary were synthesized via a versatile one-pot process. Subsequent asymmetric hydrophosphination of the coordinated allylic phosphine substrates generated the functionalized chiral 1,2-bis(diphenylphosphino)ethane products. The coordination properties and absolute configurations of the diphosphine ligands were established by single crystal X-ray crystallography. The optically pure 1,2-bis(diphenylphosphino)ethane ligands with ester and keto functionalities could be liberated in high yields from the corresponding dichloro palladium complexes by treatment with aqueous potassium cyanide. DOCTOR OF PHILOSOPHY (SPMS)

A new microcellular composite material with a biomimetic structure has been prepared via the supercritical fluid (SCF) technology. The resultant material has a clear biomimetic structure like bamboo and wood. The skin region is enriched with oriented high-strength thermotropic liquid crystal polymer fibrils, while the core region with polystyrene (PS) micro-cells. The diameter and density of microcells can be controlled by the processing parameters such as temperature and pressure. And the skin thickness can be controlled conveniently by varying the composition of polystyrene and liquid crystal polymer.

Aldehyde, ester- and keto-functionalized monophosphine palladium complexes containing the ortho-metalated (R)-(1-(dimethylamino)ethyl)naphthalene as the chiral auxiliary and reaction promoter were synthesized via hydrophosphination of acrolein and the subsequent Wittig reactions in a one-pot process. Under very mild conditions, the second-stage hydrophosphination of the monophosphine substrates gave the corresponding ester-, keto-, and hydroxyl-functionalized chiral 1,3-bis(diphenylphosphino)propane palladium complexes with good yields and stereoselectivities. The coordination properties and absolute configurations of the novel 1,3-diphosphine complexes were established by single crystal X-ray crystallography. The enantiomerically pure functionalized diphosphine ligands with ester and keto functionalities could be subsequently liberated stereospecifically by treatment of the corresponding dichloro palladium complexes with aqueous potassium cyanide in high yields.

Optically pure P-chiral 1,2- and 1,3-diphosphines were synthesized chemoselectively and stereoselectively from the chiral organopalladium complex promoted asymmetric Diels–Alder reaction between 3,4-dimethyl-1-phenylphosphole (DMPP) and cis- and trans-ester substituted allylic phosphines.

Power supply reliability can reflect the overall quality and safety management of power system. But statistical analysis for low voltage power supply reliability is still difficult mainly due to the limit of investment. In this paper, a monitoring and statistical analysis system for power supply reliability estimation of low voltage consumers is developed. In this method, it is proposed to set some suitable low voltage reliability monitoring points according to measurement precision requirement. The operation data collected by the monitoring points was transmitted to monitoring center for automatic computation and analysis. By setting suitable monitoring points scientifically and analyzing the collected data statistically, it is possible to control statistical error to a reasonable range with a much lower investment. Practical application results of the low voltage network in Jinan illustrate that this method is valid and feasible for the current low voltage system and technical equipment condition in China.