909 research outputs found

    Optimisation of nickel electrodeposition solutions for power usage

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    If electroplating processes are to be truly ‘green’ a number of issues must be addressed, notably water and electrical power usage. Electricity is used both for the driving of the process itself and for some of the process conditions, eg. temperature, agitation etc. The study of solution conductivity for electroplating solutions shows how some electrical power saving can be achieved. In the case of nickel small gains can be made by optimising solution concentrations but greater gains are attainable by the use of air-free agitation

    An Analysis on Syntactic and Semantic Factors Found in Newspaper Headlines

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    As a type of media text, newspaper has an important role in human\u27s life because it presents various local, national and International information and events. In order to attract readers\u27 attention, journalists make the headlines as ambiguous and confusing as possible so that readers are curious to know the content of the whole story and they would read it. Moreover, in presenting the information or events, different reporters will have different linguistic choices which include the choice of words and expressions and different linguistic structures. Thus, this paper analyzes how the different linguistic choices and structures used in the headlines of The Jakarta Post and Indonesian Daily News would construct different linguistic representations of events in the world

    The progenitors of type Ia supernovae in the semidetached binaries with red giant donors

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    Context. The companions of the exploding carbon-oxygen white dwarfs (CO WDs) for producing type Ia supernovae (SNe Ia) are still not conclusively confirmed. A red-giant (RG) star has been suggested to be the mass donor of the exploding WD, named as the symbiotic channel. However, previous studies on the this channel gave a relatively low rate of SNe Ia. Aims. We aim to systematically investigate the parameter space, Galactic rates and delay time distributions of SNe Ia from the symbiotic channel by employing a revised mass-transfer prescription. Methods. We adopted an integrated mass-transfer prescription to calculate the mass-transfer process from a RG star onto the WD. In this prescription, the mass-transfer rate varies with the local material states. Results. We evolved a large number of WD+RG systems, and found that the parameter space of WD+RG systems for producing SNe Ia is significantly enlarged. This channel could produce SNe Ia with intermediate and old ages, contributing to at most 5% of all SNe Ia in the Galaxy. Our model increases the SN Ia rate from this channel by a factor of 5. We suggest that the symbiotic systems RS Oph and T CrB are strong candidates for the progenitors of SNe Ia.Comment: 8 pages, 6 figure

    Affirmative action in education and Black Economic Empowerment in the workplace in South Africa since 1994: policies, strengths and limitations

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    This paper explains the concepts of Affirmative Action (AA) and Black Economic Empowerment (BEE) and the policies developed in post-Apartheid South Africa. It compares it to similar policies adopted in different contexts in Malaysia, India and the U.S.A. It explains and critiques the South African policies on AA and BEE, its history since 1994 and how class has replaced race as the determinant of who succeeds in education and the workplace. It analyses why these policies were essential to address the massive racial divide in education and the workplace at the arrival of democracy in 1994, but also why it has been controversial and racially divisive. The strengths and limitations of these policies are juxtaposed, the way it has benefitted the black and white elites, bolstered the black middle-class but has had little success in addressing the education and job futures of poor, working class black citizens in South Africa. The views of a number of key social analysts in the field are stated to explain the moral, racial, divisive aspects of AA in relation to the international experience and how South Africa is grappling with limited success to bridge the divide between the rich and poor

    Molecular dynamics simulation of fracture and energy dissipation in polymer/clay nanocomposites

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    Molecular dynamics simulation method was used to investigate the effect of nanofillers on fracture strength and energy dissipation of polymers, including nanofillers contents, interaction strength between the nanofillers and polymer chains, relaxation time and geometry of the nanofillers. Molecular dynamics simulation results revealed that the addition of layered silicate can improve the fracture strength of polymers. The interactions between the surface of layered silicate and polymer chains, and the difference between the relaxation times of layered silicate and that f polymer chains have significant influences on the fracture strength and energy dissipation of polymers. For these polymers, which Tgs are lower than room temperature, such as polyurethane, or nearby (or equal to) room temperature, such as Nylons, the nanoplatelets can always enhance the mechanical properties. However, for these polymers, which Tgs are higher than room temperature, such as epoxy and polystyrene, the addition of the nanoplatelets does not work well for toughening these polymers. If one wants the nanoplatelets to be working for toughening these polymers, it is necessary to build up a stress relaxation interface between the polymer matrix and the nanoplatelets, such as the modification of the surfaces of nanofillers using coupling agents. When the relaxation time of the polymer is long enough, the incorporation of nanofillers into the polymer will cause the polymer to become more brittle. This result explains why the toughness of epoxy/ clay nanocomposites becomes poor. The simulation results clearly revealed that' the orientation of nanoplatelets is reversible at low strain of 50% suggesting that additional energy dissipation only results from the frictional sliding at the interface, whereas the orientatiqn of nanoplatelets at large strain of 200% showed more irreversibility suggesting that the additional energy loss results from both the interfacial frictional sliding and the orientation of the nanoplatelets. The additional dissipated energy was also influenced by the strength of interactions between polymer chains and clay platelets. The stronger interactions the more energy dissipated. Molecular dynamics simulation results revealed that the geometry of nanofillers also affect the mechanical properties of polymer nanocomposites. The enhancement if carbon nanotubes on the mechanical properties of the polymers are enhanced the greatest by carbon nanotubes

    Sensitive Monitoring of Fluoroquinolones in Milk and Honey Using Multiple Monolithic Fiber Solid-Phase Microextraction Coupled to Liquid Chromatography Tandem Mass Spectrometry

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    In the present study, a new multiple monolithic fiber solid-phase microextraction (MMF-SPME) based on poly­(apronal-<i>co</i>-divinylbenzene/ethylenedimethacrylate) monolith (APDE) was synthesized. The effect of the preparation parameters of APED on extraction efficiency was studied thoroughly. The combination of APDE/MMF-SPME with high-performance liquid chromatography tandem mass spectrometry detection (HPLC/MS-MS) was developed for sensitive monitoring of ultratrace fluoroquinolones (FQs) in foodstuffs, including milk and honey samples. Under the optimized experimental conditions, the limits of detection (S/N = 3) for the targeted FQs ranged from 0.0019 to 0.018 μg/kg in milk and 0.0010 to 0.0028 μg/kg in honey. The relative standard deviations (RSDs) for method reproducibility were less than 9% in all samples. The established method was successfully applied for the monitoring of FQs residues in milk and honey samples with the recoveries between 74.5% and 116% (RSDs were in the range 0.9–9.5%). In comparison to previous methods, the developed APDE/MMF-SPME-HPLC/MS-MS showed some merits, including satisfactory sensitivity, simplicity, high cost-effectiveness, and low consumption of organic solvent

    Quantitative Proteomics Reveals Potential Crosstalk between a Small RNA CoaR and a Two-Component Regulator Slr1037 in <i>Synechocystis</i> sp. PCC6803

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    Bacterial small RNAs (sRNAs) and two-component systems (TCSs) were two vital regulatory mechanisms employed by microorganisms to respond to environmental changes and stresses. As a promising “autotrophic cell factory”, photosynthetic cyanobacteria have attracted a lot of attention these years. Although most studies focused on studying the roles of sRNAs or TCS regulators in stress response in photosynthetic cyanobacteria, limited work has elucidated their potential crosstalk. Our previous work has identified a negative sRNA regulator CoaR and a positive response regulator Slr1037 both related to 1-butanol stress regulation in <i>Synechocystis</i> sp. PCC6803. In this work, the potential crosstalk between CoaR and Slr1307 (i.e., the coregulated genes mediated by CoaR and Slr1037) was identified and validated through quantitative proteomics and quantitative real-time PCR (qRT-PCR), respectively. The results showed that the sensitive phenotype to 1-butanol of Δ<i>slr1037</i> could be rescued by suppressing <i>coaR</i> in Δ<i>slr1037</i>, probably due to the fact that some target genes of Slr1037 could be reactivated by repression of CoaR. Twenty-eight coregulated proteins mediated by CoaR and Slr1037 were found through quantitative proteomics, and 10 of the annotated proteins were validated via qRT-PCR. This study proved the existence of crosstalk between sRNAs and response regulators and provided new insights into the coregulation of biofuel resistance in cyanobacteria

    The TAIOM NPS (Sediment, NPS-N and NPS-P) load obtained during the post-BMP period.

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    <p>The TAIOM NPS (Sediment, NPS-N and NPS-P) load obtained during the post-BMP period.</p

    The goodness-of-fit results obtained during the calibration and verification period.

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    <p>The goodness-of-fit results obtained during the calibration and verification period.</p
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