Development of high-throughput, polarization-maintaining, near-field probes

A novel, chemical-etching technique produces very high throughput, polarization-maintaining probes for near-field, scanning, optical microscopy (NSOM). The process includes coating the tips with aluminum and forming the apertures with a focused ion beam (FIB). The elliptical core fibers used resulted in elliptical apertures for the probes. The throughput of the probes depends on the incident polarization. For polarization parallel to the minor axis, the tip presents an insertion loss of only 20 dB for aperture widths of 55 nm. Probes have a typical polarization extinction of 100 to 1 in the far field. These tips produced NSOM images of gold dots on a GaAs substrate in reflection mode.     

Targeting and penetration of virus receptor bearing cells by nanoparticles coated with envelope proteins of Moloney murine leukemia virus

One of the most important steps in a productive viral infection is when the virus fuses to a cell membrane and delivers its genome into the cell cytosol. This dynamic event is mediated by interactions between specific virus envelope proteins with their cell-bound receptors. This process is exemplified by Moloney murine leukemia virus (Mo-MLV) where envelope protein interaction with its receptor, mCAT-1, leads to virus-cell membrane fusion and infection of cells. Here, fluorescent nanoparticles (NPs) were coated with Mo-MLV derived membranes (Mo-NPs) by extrusion. Electron microscopy and biochemical analysis showed tight association of the virus membranes and NPs. The coated NPs mimic native virus by binding and entering only cells expressing the virus receptor. Confocal microscopy revealed that the coated NPs were taken up into endocytic compartments containing receptor and were also seen associated with caveolin, a marker of caveolae. To demonstrate that the Mo-NPs could escape endosomes and deliver a protein cargo into the cell cytosol, beta-lactamase (betalac) was covalently coupled to the Mo-NP cores and incubated with cells. betalac activity was only detected in the cytosol of mCAT-1-expressing cells. This is the first time that virus proteins have been used to specifically target NPs to receptor-bearing cells as well as penetration into the cell cytosol. Extrusion provides a rapid, detergent-free method to couple virus membranes to NPs and should be readily applicable for many other virus and NP types.     

New non-platinum Ir–V–Mo electro-catalyst,catalytic activity and CO tolerance in hydrogen oxidation reaction

Very active 40%Ir–10%V–3%Mo/C and 40%Ir–10%V–10%Mo/C (in weight) catalysts, as novel, suitable anode electrode materials in polymer electrolyte membrane fuel cells (PEMFCs), have been synthesized by an ethylene glycol (EG) reduction method. The nanostructured catalysts have been characterized by X-ray diffraction (XRD) and high-resolution transmission electron microscopy (TEM). Ir nanoparticles, after modification with V and further with Mo, show a narrow particle size distribution centered at 2 nm, and are uniformly dispersed on Vulcan XC-72 supports. Investigation of the catalytic activity by means of linear sweep voltammetry (LSV) employing a rotating disk electrode (RDE) has revealed that 40%Ir–10%V–10%Mo/C catalyst exhibited very high electrocatalytic activity toward the hydrogen oxidation reaction (HOR). About 77% higher current density was obtained for 40%Ir–10%V–10%Mo/C compared to that of 40 wt.% commercial carbon-supported platinum catalyst (Pt/C), and 282% higher current density compared to that of the pure 40 wt.% Ir/C at 0.1 V versus RHE. The performance of a membrane electrode assembly (MEA) prepared with the 40%Ir–10%V–10%Mo/C as the anode catalyst generated a maximum power density of 598.4 mW cm⁻² at 70 °C, which is 26.4% higher than that of commercially available Pt/C under air/H₂ testing condition. The ternary 40%Ir–10%V–10%Mo/C catalyst was also tested for 10 ppm CO tolerance, and the results showed that the 40%Ir–10%V–10%Mo/C has much better CO tolerance than commercial Pt/C catalyst. The mechanism of the ternary 40%Ir–10%V–10%Mo/C catalyst may be a bi-functional mechanism.     

Optimizing the methods of synthesis for barium hexagonal ferrite—An experimental and theoretical study

M-type barium hexaferrite (BaM) is a hard ferrite, crystallizing in space group P6₃/mmc possessing a hexagonal magneto-plumbite structure, which consists of alternate hexagonal and spinel blocks. The structure of BaM is thus related to those of garnet and spinel ferrite. However the material has proved difficult to synthesize. By taking into account the presence of the spinel block in barium hexagonal ferrite, highly efficient new synthetic methods were devised with routes significantly different from existing ones. These successful variations in synthetic methods have been derived by taking into account a detailed investigation of the structural features of barium hexagonal ferrite and the least change principle whereby configuration changes are kept to a minimum. Thus considering the relevant mechanisms has helped to improve the synthesis efficiencies for both hydrothermal and co-precipitation methods by choosing conditions that invoke the formation of the cubic block or the less stable Fe₃O₄. The role played by BaFe₂O₄ in the synthesis is also discussed. The distribution of iron from reactants or intermediates among different sites was also successfully explained. The proposed mechanisms are based on the principle that the cubic block must be self-assembled to form the final product. Thus, it is believed that these formulated mechanisms should be helpful in designing experiments to obtain a deeper understanding of the synthesis process and to investigate the substitution of magnetic ions with doping ions.     

Highly active and durable core-corona structured bifunctional catalyst for rechargeable metal-air battery application

A new class of core-corona structured bifunctional catalyst (CCBC) consisting of lanthanum nickelate centers supporting nitrogen-doped carbon nanotubes (NCNT) has been developed for rechargeable metal-air battery application. The nanostructured design of the catalyst allows the core and corona to catalyze the oxygen evolution reaction (OER) and oxygen reduction reaction (ORR), respectively. These materials displayed exemplary OER and ORR activity through half-cell testing, comparable to state of the art commercial lanthanum nickelate (LaNiO(3)) and carbon-supported platinum (Pt/C), with added bifunctional capabilities allowing metal-air battery rechargeability. LaNiO(3) and Pt/C are currently the most accepted benchmark electrocatalyst materials for the OER and ORR, respectively; thus with comparable activity toward both of these reactions, CCBC are presented as a novel, inexpensive catalyst component for the cathode of rechargeable metal-air batteries. Moreover, after full-range degradation testing (FDT) CCBC retained excellent activity, retaining 3 and 13 times greater ORR and OER current upon comparison to state of the art Pt/C. Zinc-air battery performances of CCBC is in good agreement with the half-cell experiments with this bifunctional electrocatalyst displaying high activity and stability during battery discharge, charge, and cycling processes. Owing to its outstanding performance toward both the OER and ORR, comparable with the highest performing commercial catalysts to date for each of the respective reaction, coupled with high stability and rechargeability, CCBC is presented as a novel class of bifunctional catalyst material that is very applicable to future generation rechargeable metal-air batteries.     

Modeling the Heterogeneity in Contractors’ Mark-Up Behavior

Individual contractors exhibit different bidding behaviors when confronted with a given set of project decision environment factors, i.e., heterogeneity in the population of contractors. In examining the tenability of the bidder homogeneity assumption, a linear mixed modeling approach is applied to two data sets obtained from Hong Kong and Singapore contractors via a bidding experiment. Two linear mixed models were developed by relating the contractors’ mark-up decision to four project decision environment factors, namely, (1) market conditions; (2) number of bidders; (3) project type; and (4) project size. The results show that not only is there a significant heterogeneity between the Hong Kong and the Singapore contractors in terms of both their preferences (intercepts) and responses (slopes) to the project decision environment factors that affect their mark-up decision, but also that the individual Hong Kong and Singapore contractors have different degrees of sensitivity toward the project decision environment factors (which is reflected in the varying individual-specific intercepts and slopes). These individual-specific parameter estimates have implications for managerial action in formulating a firm’s competitive strategies.     

The mediating role of extreme peer orientation in the relationships between adolescent–parent relationship and diabetes management.

The study examined whether the quality of the adolescent–parent relationship was associated with better diabetes management in adolescents with Type 1 diabetes by decreasing adolescents' extreme peer orientation. Adolescents (n = 252; 46% male and 54% female) aged 10 to 14 years with Type 1 diabetes completed assessments of extreme peer orientation (i.e., tendency to ignore parental advice and diabetes care to fit in with friends), adolescent–parental relationship, and adherence; HbA1c scores indexed metabolic control. Adolescents with higher quality relationships with parents reported less peer orientation and better diabetes care. The mediational model revealed that adolescents' high quality relationships with their parents (mother and father) were associated with better treatment adherence and metabolic control through less peer orientation. It is likely that high quality adolescent–parent relationships may be beneficial to adolescent diabetes management through a healthy balance between peer and parental influence. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Spatially refined aerosol direct radiative forcing efficiencies

Global aerosol direct radiative forcing (DRF) is an important metric for assessing potential climate impacts of future emissions changes. However, the radiative consequences of emissions perturbations are not readily quantified nor well understood at the level of detail necessary to assess realistic policy options. To address this challenge, here we show how adjoint model sensitivities can be used to provide highly spatially resolved estimates of the DRF from emissions of black carbon (BC), primary organic carbon (OC), sulfur dioxide (SO(2)), and ammonia (NH(3)), using the example of emissions from each sector and country following multiple Representative Concentration Pathway (RCPs). The radiative forcing efficiencies of many individual emissions are found to differ considerably from regional or sectoral averages for NH(3), SO(2) from the power sector, and BC from domestic, industrial, transportation and biomass burning sources. Consequently, the amount of emissions controls required to attain a specific DRF varies at intracontinental scales by up to a factor of 4. These results thus demonstrate both a need and means for incorporating spatially refined aerosol DRF into analysis of future emissions scenario and design of air quality and climate change mitigation policies.     

Assessing the basic traits associated with psychopathy: Development and validation of the Elemental Psychopathy Assessment.

A new self-report assessment of the basic traits of psychopathy was developed with a general trait model of personality (five-factor model [FFM]) as a framework. Scales were written to assess maladaptive variants of the 18 FFM traits that are robustly related to psychopathy across a variety of perspectives including empirical correlations, expert ratings, and translations of extant assessments. Across 3 independent undergraduate samples (N = 210–354), the Elemental Psychopathy Assessment (EPA) scales proved to be internally consistent and unidimensional, and were strongly related to the original FFM scales from which they were derived (mean convergent r = .66). The EPA scales also demonstrated substantial incremental validity in the prediction of existing psychopathy measures over their FFM counterparts. When summed to form a psychopathy total score, the EPA was substantially correlated with 3 commonly used psychopathy measures (mean r = .81). Finally, in a small male forensic sample (N = 70), the EPA was significantly correlated with scores on a widely used self-report psychopathy measure, disciplinary infractions, alcohol use, and antisocial behavior. The EPA provides an opportunity to examine psychopathy and its nomological network through smaller, more basic units of personality rather than by scales or factors that blend these elements. (PsycINFO Database Record (c) 2011 APA, all rights reserved)