Segregation Isotherms at the Surfaces of Oxides

A non-Arrhenius segregation isotherm is derived which includes the change in the heat of segregation with surface coverage due to impurity—impurity interactions. It is shown that a linear dependence of log ( X_s ) on the reciprocal temperature, where X_s is the surface atomic ratio, can derive either from a constant heat of segregation, i.e., Arrhenius behavior, or from a heat of segregation that varies as X⁻¹_s . This isotherm is then used to calculate the equilibrium surface coverages of Ca at the {001} surface of MgO₁ Mg at the {0001} surface of α-Al₂O₃, γ at the {1012} and {1120} surfaces of α-Al₂O₃, and Na at the {111} and {110} surfaces of Li₂O from the calculated heats of segregation. Where possible, comparisons are made with experiment. The more useful operational definition of the heat of segregation, namely, that derived from the measured coverage or that defined atomistically and obtained by calculation, is discussed.     

Bacterial Killing by Light‐Triggered Release of Silver from Biomimetic Metal Nanorods

Illumination of noble metal nanoparticles at the plasmon resonance causes substantial heat generation, and the transient and highly localized temperature increases that result from this energy conversion can be exploited for photothermal therapy by plasmonically heating gold nanorods (NRs) bound to cell surfaces. Here, plasmonic heating is used for the first time to locally release silver from gold core/silver shell (Au@Ag) NRs targeted to bacterial cell walls. A novel biomimetic method of preparing Au@Ag core–shell NRs is employed, involving deposition of a thin organic polydopamine (PD) primer onto Au NR surfaces, followed by spontaneous electroless silver metallization, and conjugation of antibacterial antibodies and passivating polymers for targeting to gram‐negative and gram‐positive bacteria. Dramatic cytotoxicity of S. epidermidis and E. coli cells targeted with Au@Ag NRs is observed upon exposure to light as a result of the combined antibacterial effects of plasmonic heating and silver release. The antibacterial effect is much greater than with either plasmonic heating or silver alone, implying a strong therapeutic synergy between cell‐targeted plasmonic heating and the associated silver release upon irradiation. The findings suggest a potential antibacterial use of Au@Ag NRs when coupled with light irradiation, which has not been previously described.     

Insulator‐Conductor Type Transitions in Graphene‐Modified Silver Nanowire Networks: A Route to Inexpensive Transparent Conductors

Silver nanowire coatings are an attractive alternative to indium tin oxide for producing transparent conductors. To fabricate coatings with low sheet resistance required for touchscreen displays, a multi‐layer network of silver nanowires must be produced that may not be cost effective. This problem is counteracted here by modifying the electrical properties of an ultra‐low‐density nanowire network through local deposition of conducting graphene platelets. Unlike other solution‐processed materials, such as graphene oxide, our pristine graphene is free of oxygen functional groups, resulting in it being electrically conducting without the need for further chemical treatment. Graphene adsorption at inter‐wire junctions as well as graphene connecting adjacent wires contributes to a marked enhancement in electrical properties. Using our approach, the amount of nanowires needed to produce viable transparent electrodes could be more than 50 times less than the equivalent pristine high density nanowire networks, thus having major commercial implications. Using a laser ablation process, it is shown that the resulting films can be patterned into individual electrode structures, which is a pre‐requisite to touchscreen sensor fabrication.     

Comparison of performance of statistical models in forecasting monthly streamflow of Kizil River,China

This paper presents the application of autoregressive integrated moving average(ARIMA),seasonal ARIMA(SARIMA),and Jordan-Elman artificial neural networks(ANN)models in forecasting the monthly streamflow of the Kizil River in Xinjiang,China.Two different types of monthly streamflow data(original and deseasonalized data)were used to develop time series and Jordan-Elman ANN models using previous flow conditions as predictors.The one-month-ahead forecasting performances of all models for the testing period(1998-2005)were compared using the average monthly flow data from the Kalabeili gaging station on the Kizil River.The Jordan-Elman ANN models,using previous flow conditions as inputs,resulted in no significant improvement over time series models in one-month-ahead forecasting.The results suggest that the simple time series models(ARIMA and SARIMA)can be used in one-month-ahead streamflow forecasting at the study site with a simple and explicit model structure and a model performance similar to the Jordan-Elman ANN models.     

Synthesis of cadmium and zinc semiconductor compounds from an ionic liquid containing choline chloride and urea

A eutectic mixture of choline chloride and urea (commercially known as Reline) has been used as a medium from which CdS, CdSe, and ZnS thin films have been electrodeposited for the first time. Reline is a conductive room temperature ionic liquid (RTIL) with a wide electrochemical window, which is suitable for use as a medium for electrodeposition. The voltammetric behaviour of the Reline-Cd(II)-sulfur system has been investigated. Thin films of CdS deposited at constant potential were characterized by photocurrent and electrolyte electroabsorbance spectroscopies. Thin films of CdSe and ZnS have also been prepared, and their photocurrent excitation spectra have been measured.     

Remote atmospheric breakdown for standoff detection by using an intense short laser pulse

A remote atmospheric breakdown is a very rich source of UV and broadband visible light that could provide an early warning of the presence of chemical-biological warfare agents at extended standoff distances. A negatively chirped laser pulse propagating in air compresses in time and focuses transversely, which results in a rapid laser intensity increase and ionization near the focal region that can be located kilometers away from the laser system. Proof-of-principle laboratory experiments are performed on the generation of remote atmospheric breakdown and the spectroscopic detection of mock biological warfare agents. We have generated third harmonics at 267 nm and UV broadband radiation in air from the compression and focusing of femtosecond laser pulses. Fluorescence emission from albumin aerosols as they were illuminated by the femtosecond laser pulse has been observed.     

E-recruitment and the benefits of organizational web appeal

This study examined the influences of website design on prospective job seekers. A total of 182 participants accessed and reviewed an online job ad. Afterwards, they rated: (a) the attractiveness of the ad’s formatting, (b) the usability of the website, (c) overall evaluations of the organization’s web appeal, (d) impressions of the organization, and (e) willingness to pursue employment with the hiring organization. Although both the formatting attractiveness and usability of online recruitment materials influenced participants’ inclinations to pursue jobs, formatting was more important than usability. Moreover, impressions of the employer mediated the relationship between satisfaction with the website and willingness to pursue employment with the organization. Overall, this research advances knowledge by applying signaling theory to the web-based recruitment domain and by testing a mediated relationship implied therein. In addition, this is the first study to introduce relative weights analysis to the recruitment literature.     

A correlational analysis of skill specificity: Learning, abilities, and individual differences.

Skill specificity, the notion that task performance is based on unique underlying information-processing components at skilled levels of performance, is examined from the perspective of the ability determinants of individual differences in task performance during skill acquisition. The current investigation uses a dynamic ability-skill theoretical perspective to evaluate how individual differences in procedural learning for a complex criterion task relate to learning of procedures for other more basic tasks such as choice and simple reaction time (RT). An experiment with 86 college students was performed using a simulated Air Traffic Controller (ATC) task for assessment of procedural learning, along with practice on several perceptual speed measures and assessment of reference abilities. When Ss are allowed to practice tests of perceptual speed and psychomotor ability, some measures increase in their power to predict skilled performance on the complex ATC criterion task, a direct disconfirmation of the skill-specificity thesis. Discussion is devoted to the use of individual-differences approaches to address general transfer and skill specificity issues. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Correlation of neuropsychological function with cerebral metabolic rate in subdivisions of frontal lobes of older alcoholic patients measured with [–1–8F]fluorodeoxyglucose and positron emission tomography.

Literature concerning 2 clinical measures of concept formation, the Halstead Category Test (HCT) and the Wisconsin Card Sorting Test (WCST), indicates that these 2 tests assess different aspects of concept formation and abstraction. We studied 37 older alcoholic patients on the HCT and WCST and measured their local cerebral metabolic rate for glucose (LCMRG) with [–1–8F]fluorodeoxyglucose (FDG) and positron emission tomography (PET) in the 3 principal frontal lobe subdivisions (cingulate, dorsolateral, and orbitomedial). Performance on the summary subtest (Subtest VII) of the HCT was correlated with LCMRG in all 3 frontal subdivisions, whereas the summary WCST measure of categories achieved was correlated only with LCMRG in the cingulate region. These findings suggest that abnormalities in functioning of the subdivisions of the frontal lobe may contribute to different aspects of the behavioral impairment seen in older alcoholic patients. (PsycINFO Database Record (c) 2010 APA, all rights reserved)