Synthesis And Characterization Of Magnetite And Magnetite-Epoxy Polymers Nanocomposites And Their Thermal And Electrical Behaviors [QC176.8.N35 T161 2007 f rb].

Nanozarah magnetit (Fe3O4) disintesis melalui pemendakan beralkali. Kesan pelbagai aditif dan persekitaran akues-organik terhadap saiz, keseragaman saiz dan morfologi zarah magnetit dikaji. Magnetite (Fe3O4) nanoparticles are synthesized via alkaline precipitation. The effect of different additives and aqueous-organic environment on the size, size uniformity and morphology of magnetite particles is studied

On the location of plumes and lateral movement of thermochemical structures with high bulk modulus in the 3-D compressible mantle

The two large low shear velocity provinces (LLSVPs) at the base of the lower mantle are prominent features in all shear wave tomography models. Various lines of evidence suggest that the LLSVPs are thermochemical and are stable on the order of hundreds of million years. Hot spots and large igneous province eruption sites tend to cluster around the edges of LLSVPs. With 3-D global spherical dynamic models, we investigate the location of plumes and lateral movement of chemical structures, which are composed of dense, high bulk modulus material. With reasonable values of bulk modulus and density anomalies, we find that the anomalous material forms dome-like structures with steep edges, which can survive for billions of years before being entrained. We find that more plumes occur near the edges, rather than on top, of the chemical domes. Moreover, plumes near the edges of domes have higher temperatures than those atop the domes. We find that the location of the downwelling region (subduction) controls the direction and speed of the lateral movement of domes. Domes tend to move away from subduction zones. The domes could remain relatively stationary when distant from subduction but would migrate rapidly when a new subduction zone initiates above. Generally, we find that a segment of a dome edge can be stationary for 200 million years, while other segments have rapid lateral movement. In the presence of time-dependent subduction, the computations suggest that maintaining the lateral fixity of the LLSVPs at the core-mantle boundary for longer than hundreds of million years is a challenge

Thermal Behaviors And Ionic Conductivity Of Composite Enr-50-Based Polymer Electrolytes

The synthesis of polymer electrolytes (PEs) and composite polymer electrolytes (CPEs) using epoxidized natural rubber (ENR-50) as the host matrix and magnetite (Fe3O4) nanoparticles as the inorganic filler was carried out. These were characterized by FTIR, SEM/X-mapping, TEM, XRD, DSC, TGA and EIS. The influence of lithium salt, LiX (where X = BF4 -, I-, CF3SO3 -, COOCF3 - and ClO4 -) with various anions and iodide salt, MI (where M = Li+, Na+, K+ and Ag+) with different cations on the properties and degradation of PEs was investigated. This was followed by the study of the simultaneous presence of Fe3O4 nanoparticles in various LiX-ENR-50 PE systems. The study on sole Fe3O4/ENR-50 composites was also performed for comparison purposes. The trend in thermal stability and ionic conductivity of LiX-ENR-50 PEs is in the order of LiBF4 >> LiCF3SO3 ~ LiCOOCF3 > LiI >> LiClO4. The LiClO4 hardly dissociates and formed LiClO4 aggregates within the ENR-50 matrix that resulted in a PE with low thermal stability and low ionic conductivity. The LiCF3SO3, LiCOOCF3 and LiI exert moderate interactions with the ENR-50 and their respective PEs exhibit moderate ionic conductivity and thermal property. The occurrence of epoxide ring opening and complexation or cross-linking reactions in and between the ENR-50 chains that involve BF4 - ions have produced a LiBF4-ENR-50 PE with superior thermal stability and ionic conductivity as compared to other LiX-ENR-50 PEs studied in this work. The impedance properties of MI-ENR-50 PEs are closely related to the solubility, interaction and the outcome morphology of MI salt in the ENR-50. The solubility of MI salt in the ENR-50 follows the decreasing trend of LiI > NaI > KI > AgI. In PEs, the LiI mostly exists in ions and the Li+ are pseudo-crosslinked with the epoxide in the ENR-50 chains. Other MI salts are hardly dissociated in the ENR-50 which exert weak or no chemical interaction with the ENR-50. The thermal stability of ENR-50 in PEs is dependant on the type of metal in the MI salt. The alkali metal like Li, Na and K does not greatly influence the stability of ENR-50. Nonetheless, the presence of AgI destabilizes the ENR-50 in PE. The degradation of ENR-50 in LiClO4-, NaI- and KIENR- 50 PE is similar to purified ENR-50 due to weak salt-ENR-50 interaction. It initiates with first-order reaction (F1) followed by 3-dimensional diffusion control (D3) reaction. The presence of other salts in PE caused the degradation of ENR-50 to follow only a D3 type model

Magnetic Leakage Internal Detection Device and Series-Parallel Detection Method for Small Diameter Ferromagnetic Spiral Heat Exchanger Tubes

Based on the calculation of magnetic circuit of the detection probe, this article designs a kind of magnetic leakage detection device and series-parallel detection method of small diameter spiral heat exchange tube to realize the safety detection of small diameter spiral heat exchange tube. The detection device includes a detection probe and a probe drive mechanism, which drives the detection probe to move in the spiral heat exchange tube. The detection probe includes an intermediate connector, a magnetizer which is arranged coaxially at both ends of the intermediate connector in turn, a steel ball support body and an end connector. The designed detection probes are mixed in series and parallel, and multiple detection probes are put together in series to be placed in a spiral heat exchange tube to form a group of detection probes in series. Then, multiple groups of detection probes in series are placed in each spiral heat exchange pipe, forming a series-parallel combination, which can detect multiple spiral heat exchange pipes at the same time and improve the detection efficiency greatly

Genetic Variation Of Kelampayan (Neolamarckia Cadamba) Trees For Planted Forest Development In Sarawak

Neolamarckia cadamba is now a commercially important plantation species, and is seen slowly but surely replacing other exotic species. Therefore, it is crucial that we have the tools to determine the genetic variation of N. cadamba that occurs in Sarawak, both for natural and planted populations. The objective of this study is to assess the genetic variation of N. cadamba from different areas in Sarawak by random amplified polymorphic DNA (RAPD) markers. To date, leaf samples from a total of 162 individual trees have been collected from five populations, namely: Matang, Sabal and Simunjan, Bintulu, Miri and Sibu. Total genomic DNA is isolated from the silicagel‐ preserved leaf samples, and subsequently the isolated DNA is analysed using RAPD technique. The RAPD marker detects DNA variations that result in the loss or gain of DNA fragments at a particular location in the Kelampayan genome. These variations will help us determine genetic relatedness and diversity between different Kelampayan populations. The results of this study will provide a foundation in the selection of plus trees, establishment of forest seed production areas, and subsequently production of high quality seedlings for plantations with all the desirable characteristics in term of growth rate, bole form, wood density and disease resistance

COMPARISON OF LABORATORY AND INDUSTRIAL SACCHAROMYCES CEREVISIAE STRAINS FOR THEIR INHIBITOR RESISTANCE AND XYLOSE UTILIZATION

There are various kinds of stresses during the process of ethanol fermentation and more inhibitory factors are produced when lignocelluloses hydrolysate is used as the substrate. The pretreatment of lignocelluloses biomass before fermentation causes the increase in the amount of acids and thus the decrease in pH. Low-molecular weight aliphatic acids, furaldehydes and a broad range of aromatic compounds are produced during the pretreatment process. They are the inhibitors for the ethanol producers, such as Saccharomyces cerevisiae. Furthermore, besides glucose, lignocellulose hydrolysate contains other sugars, such as xylose, arabinose, galactose and mannose etc., among which xylose is taking the major proportion. Stress tolerance and xylose utilization are therefore essential for Saccharomyces cerevisiae strains to get high-efficiency fermentation and high-yield ethanol production. In this study, a few laboratory and industrial Saccharomyces cerevisiae strains were selected for the evaluation of their potentials in pH tolerance, inhibitor resistance and xylose utilization. Industrial strains such as TJU (an industrial strain used in some of the bioethanol plants in China), ATCC 4126, and ATCC 96581, an isolate from spent sulfite liquor were compared with some laboratory strains such as ATCC 44771, ATCC 24860 and CBS 8066. The difference of these strains in their pH tolerance was insignificant despite the fact that almost all the strains had less growth when pH was below 4. Among all the yeast strains tested, the haploid laboratory strain ATCC 44771 showed the lowest tolerance to the decrease of pH. As to the inhibitor resistance studies almost all the industrial strains tested had higher inhibitor resistance than the laboratory strains, with ATCC 44771 being the least resistant to the increase in the inhibitor concentrations. The laboratory strain ATCC 24860 showed almost equivalent inhibitor resistance compared with these industrial strains. Further analysis of these strains on their xylose utilization was carried out. Random mutagenesis followed by xylose adaptation was applied. Almost all the laboratory strains died after mutation and all the industrial strains survived with their xylose unitization capabilities increased. In addition, the presence of inhibitors such as 5-hydroxymethylfurfural (HMF) and furfural had enhanced their xylsoe assimilation. The above analysis indicated that industrial Saccharomyces cerevisiae strains could be trained for biomass hydrolysate fermentation as they have high pH tolerance, high inhibitor resistance and potentials in xylose utilization. As such, the potential xylose-utilizing mutants are being evaluated for their potentials in biomass hydrolysate fermentation

Automatic human guided shopping trolley with smart shopping system

A shopping trolley is a necessary tool for shopping in supermarkets or grocery stores. However, there are shopping trolleys abandoned everywhere in supermarkets after being used. In addition, there are also shopping trolley safety issues such as sliding down from an escalator. It is known to be an inconvenience and time wasting for customers who are in rush to search for desired products in a supermarket. Therefore, an automatic human and line following shopping trolley with a smart shopping system is developed to solve these problems. A line following portable robot is installed under the trolley to lead the users to the items’ location that they plan to purchase in the supermarket. This paper presents the hardware and software design of the portable robot. The result of the testing on the used sensors like ultrasonic and line sensors are presented. Lastly, the graphical user interface of Android application during the shopping trolley in operation is explained

Roles and recommendations from primary care physicians towards managing low-risk breast cancer survivors in a shared-care model with specialists in Singapore-a qualitative study.

BackgroundBreast cancer is prevalent and has high cure rates. The resultant increase in numbers of breast cancer survivors (BCS) may overwhelm the current oncology workforce in years to come. We postulate that primary care physicians (PCPs) could play an expanded role in comanaging survivors, provided they are given the appropriate tools and training to do so.ObjectiveTo explore the perspectives of PCPs towards managing BCS in a community-based shared-care programme with oncologists.MethodsEleven focus groups and six in-depth interviews were conducted with seventy PCPs recruited by purposive sampling. All sessions were audio-recorded, transcribed verbatim and coded by three independent investigators. Thematic data analysis was performed and the coding process facilitated by NVivo 12.ResultsMajority of PCPs reported currently limited roles in managing acute and non-cancer issues, optimizing comorbidities and preventive care. PCPs aspired to expand their role to include cancer surveillance, risk assessment and addressing unmet psychosocial needs. PCPs preferred to harmonize cancer survivorship management of their primary care patients who are also BCS, with defined role distinct from oncologists. Training to understand the care protocol, enhancement of communication skills, confidence and trust were deemed necessary. PCPs proposed selection criteria of BCS and adequacy of their medical information; increased consultation time; contact details and timely access to oncologists (if needed) in the shared-care programme.ConclusionsPCPs were willing to share the care of BCS with oncologists but recommended role definition, training, clinical protocol, resources and access to oncologist's consultation to optimize the programme implementation

Plasma and urine metabolite profiling reveals the protective effect of Clinacanthus nutans in an ovalbumin-induced anaphylaxis model: ¹H-NMR metabolomics approach

The present study sought to identify the key biomarkers and pathways involved in the induction of allergic sensitization to ovalbumin and to elucidate the potential anti-anaphylaxis property of Clinacanthus nutans (Burm. f.) Lindau water leaf extract, a Southeast Asia herb in an in vivo ovalbumin-induced active systemic anaphylaxis model evaluated by 1H-NMR metabolomics. The results revealed that carbohydrate metabolism (glucose, myo-inositol, galactarate) and lipid metabolism (glycerol, choline, sn-glycero-3-phosphocholine) are the key requisites for the induction of anaphylaxis reaction. Sensitized rats treated with 2000 mg/kg bw C. nutans extract before ovalbumin challenge showed a positive correlation with the normal group and was negatively related to the induced group. Further 1H-NMR analysis in complement with Kyoto Encyclopedia of Genes and Genomes (KEGG) reveals the protective effect of C. nutans extract against ovalbumin-induced anaphylaxis through the down-regulation of lipid metabolism (choline, sn-glycero-3-phosphocholine), carbohydrate and signal transduction system (glucose, myo-inositol, galactarate) and up-regulation of citrate cycle intermediates (citrate, 2-oxoglutarate, succinate), propanoate metabolism (1,2-propanediol), amino acid metabolism (betaine, N,N-dimethylglycine, methylguanidine, valine) and nucleotide metabolism (malonate, allantoin). In summary, this study reports for the first time, C. nutans water extract is a potential anti-anaphylactic agent and 1H-NMR metabolomics is a great alternative analytical tool to explicate the mechanism of action of anaphylaxis

Synthesis of Dispersed and Self-Assembled Metal Particles in Epoxy via Aqueous to Organic Phase Transfer Technique

A convenient and effective method of dispersing gold (Au), silver (Ag) and copper (Cu) particles in epoxy is described. Particles were synthesized in aqueous phase and subsequently dispersed in toluene-epoxy with or without the presence of curing agent. Sodium borohydride and 2-propanol were used as reducing and phase transfer agents respectively. The surface plasmon resonance (SPR) at ~ 540-620 nm, ~ 525 nm and ~450 nm confirms the presence of Cu, Au and Ag nanoparticles in the composites. No chemical interaction occurred between the metal particles and the epoxy or cured epoxy. Increase in epoxy content caused the size of the particles to decrease for all metals. The average particle size for Au, Ag and Cu in 1% and 10% epoxy are 3.9 nm and 2.5 nm, 10.1 nm and 3.2 nm as well as 8.1 nm and 5.9 nm respectively. Similar decreasing trend was also observed upon addition of curing agent. In all cases, metal nanoparticles exhibit self-assembly with inter-particle spacing of <10 nm. The absence of any curing peak in the DSC thermograms suggests that the composites are well cured before any of the DSC analyses were performed. The Tg of the metal-cured epoxy is higher than neat epoxy, that is 71.3 °C, 69.8 °C and 62.0 °C for Cu, Au and Ag respectively