The effects of groups' variety and disparity on groups' cognitive complexity.

This study examined the influence of group diversity conceptualized as disparity and as variety on group cognitive complexity. Data on individual cognitive complexity and group cognitive complexity were collected in 44 groups using a conceptual mapping technique. Also data on the quality of teamwork processes and satisfaction were collected using an individual questionnaire. The results indicate that (a) gender variety has a positive impact on group cognitive complexity, (b) cognitive disparity has a negative impact on group cognitive complexity, and (c) groups with a high average individual cognitive complexity have the highest cognitive complexity as a group only if the quality of their interactions is high. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Schottky barrier versus surface ferroelectric depolarization at Cu/Pb(Zr,Ti)O3 interfaces

The band bending at Cu/PZT(001) interfaces is investigated by X-ray photoelectron spectroscopy (XPS) for a PZT(001) layer which exhibits initial outwards ferroelectric polarization. Two competitive processes are identified: (a) formation of the Schottky barrier between the ferroelectric and unconnected Cu islands, and (b) coalescence of the Cu islands, realisation of an electrical contact to the ground of the system, inducing the apparent loss of the component of the ferroelectric polarization perpendicular to the sample surface, at least as it manifests in band bending. Three mechanisms are proposed to explain this loss of band bending when a full metal layer connected to ground is formed on the surface: (i) over-compensation of depolarization field in the sub-surface region, (ii) formation of domains with in-plane orientation of the polarization vector and (iii) loss of polarization in the near-surface layers of the ferroelectric due to electrons provided by the metal. These result in a non-monotonous variation of binding energies with the amount of Cu deposited. High resolution transmission electron microscopy and piezoresponse force microscopy confirmed these hypotheses. The XPS data allowed also to derive the surface PZT composition, its evolution with the deposition of copper and the formation of surface compounds.     

Sensitivity of static noise margins to random dopant variations in 6-T SRAM cells

The random dopant induced fluctuations of static noise margins (SNM) in 6-T SRAM cells are analyzed by using the formalism of doping sensitivity functions, which show how sensitive the SNM are to variations of the doping concentration at different locations inside the cell. The technique presented in this article is based on a full circuit perturbation theory at the level of each device transport model. It provides important information for the design and optimization of SNM and can capture correlation effects of doping fluctuations inside the same semiconductor device and between more devices. The bias points and the magnitude of random dopant induced fluctuations are computed by solving the Poisson, current continuity, and density–gradient equations for all the devices self-consistently (mixed-mode simulation). Simulation results for a well scaled SRAM cell with 30 nm channel length transistors show that the most sensitive regions to doping fluctuations extend for approximately 10 nm below the oxide/semiconductor interface and are located in the middle of the conduction channels for both the p-channel and n-channel transistors. It is apparent that random dopant induced fluctuations can significantly impinge on the yield and reliability of SRAM circuits and constitute a fundamental limit for further scaling unless these devices are properly optimized.     

Design of random doping fluctuation resistant structures of semiconductor devices

An automated technique is presented for the computation of the doping profiles that minimize the intrinsic fluctuations of various parameters induced by random doping fluctuations in semiconductor devices. The technique is based on the computation of the doping sensitivity functions of the parameters under consideration and the constrained minimization of the standard deviation of fluctuations by using the Lagrange multipliers technique. The technique is then applied to the minimization of the random doping induced fluctuations of the threshold voltage in 40-nm channel length MOSFET device.     

SN-38 loading capacity of hydrophobic polymer blend nanoparticles: formulation,optimization and efficacy evaluation

One of the most important problems in nanoencapsulation of extremely hydrophobic drugs is poor drug loading due to rapid drug crystallization outside the polymer core. The effort to use nanoprecipitation, as a simple one-step procedure with good reproducibility and FDA approved polymers like Poly(lactic-co-glycolic acid) (PLGA) and Polycaprolactone (PCL), will only potentiate this issue. Considering that drug loading is one of the key defining characteristics, in this study we attempted to examine whether the nanoparticle (NP) core composed of two hydrophobic polymers will provide increased drug loading for 7-Ethyl-10-hydroxy-camptothecin (SN-38), relative to NPs prepared using individual polymers. D-optimal design was applied to optimize PLGA/PCL ratio in the polymer blend and the mode of addition of the amphiphilic copolymer Lutrol^®F127 in order to maximize SN-38 loading and obtain NPs with acceptable size for passive tumor targeting. Drug/polymer and polymer/polymer interaction analysis pointed to high degree of compatibility and miscibility among both hydrophobic polymers, providing core configuration with higher drug loading capacity. Toxicity studies outlined the biocompatibility of the blank NPs. Increased in vitro efficacy of drug-loaded NPs compared to the free drug was confirmed by growth inhibition studies using SW-480 cell line. Additionally, the optimized NP formulation showed very promising blood circulation profile with elimination half-time of 7.4?h.     

Statistical Evaluation of Factors Affecting the Leaching Process of Waste Electrical and Electronic Equipment using Sodium Persulfate

Recycling of waste electrical and electronic equipment (WEEE) is important not only to reduce the amount of waste requiring treatment, but also to promote the recovery of valuable materials. Implementation of the European Directive on WEEE and recycling targets imposed in the European Union will require new processes to be developed and applied to recover metals from WEEE. This study aims to provide an alternative process for the dissolution of metals from WEEE which contains Cu and Zn based on our previous research. The effects of leaching parameters, such as temperature, Na₂S₂O₈ concentration, and leaching time, were separately investigated on leaching of copper, zinc, and brass (alloy composition ?35% zinc and 65% copper) in Na₂S₂O₈ solution (0.1, 0.2 and 0.3 M). Box–Behnken experimental design (BBD) method was used to determine the number and the condition of necessary leaching experiments. Statistical analysis of variance (ANOVA) was performed to see whether process parameters such as leaching time, temperature, and oxidant concentration are statistically significant or not on the leaching performance. Results show leaching time as the most influential factor in the dissolution process, for the first six models. Two extended models have been developed to optimize the parameters of the investigated process. In these models, we consider the metal composition as a model input next to the earlier investigated parameters. Optimal condition for maximum copper and zinc dissolution in Na₂S₂O₈ environment can be found for parameter values: temperature 45°C, oxidant concentration 0.1 M and leaching time 35 min.     

Radiation processing of ethylene‐propylene rubber

The effects of ionizing radiation on ethylene‐propylene copolymer were evaluated over the range of total γ doses up to 500 kGy. The influence of the irradiation dose was investigated by oxygen uptake and thermal analysis. Four testing temperatures (170, 180, 190, and 200°C) and two heating rates between 2.9 and 5.9 K/min were selected for oxygen uptake measurements and thermal analysis, respectively. The competition between crosslinking and scission was examined on the basis of kinetic parameters of postirradiation oxidation. The influence of the momentary concentration of hydrocarbon free radicals is discussed in regard to the contribution of the antagonistic processes of crosslinking and oxidative degradation. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 298–303, 2000     

Effect of gadolinium ions on the structure and magnetic properties of zinc-borate glasses and glass ceramics

X-ray diffraction (XRD), electron paramagnetic resonance (EPR), and magnetic susceptibility measurements have been employed to investigate the samples from the (Gd₂O₃) _x ·(B₂O₃)_(60−x)·(ZnO)₄₀ (0 ≤ x ≤ 20 mol%) system. The XRD pattern for the prepared samples shows that the vitreous phase is present only for x ≤ 15 mol%. For the samples containing 20 mol% Gd₂O₃ the presence of a unique crystalline phase, GdBO₃, embedded in a vitreous matrix was evidenced. In this case the XRD patterns show the presence of nanometer sized crystals (64 nm) in a glassy matrix. The EPR spectra of the studied samples exhibit three important features with effective g-values of ≈6, 2.8, 2.0 and a weaker feature at g ≈ 4.8. For low Gd₂O₃ contents (x < 3 mol%), the EPR spectra have the typical ‘‘U’’-type shape. For higher contents of Gd₂O₃ (x ≥ 3 mol%), the spectral features are broadened and finally are dominated by a single broad absorption line located at g ≈ 2.0. This broad EPR line is associated to the Gd³⁺ ions present predominantly as clustered species. Magnetic susceptibility data show that for x > 1 mol% the Gd³⁺ ions are present not only as isolated species but also as species coupled through antiferromagnetic exchange interactions.     

Does conflict shatter trust or does trust obliterate conflict? Revisiting the relationships between team diversity, conflict, and trust.

This article explores the interplay between trust and conflict as antecedents of team effectiveness. In the first cross-sectional study, two alternative path models are tested in a sample of 174 teams (897 participants) with the emergent states of task conflict, relationship conflict, and trust acting as mediators between team demographic diversity (gender and nationality) on the one hand and perceived team effectiveness on the other. In one model trust is considered as an antecedent for the two types of conflict, while in the other the two types of conflict precede the emergence of trust. Although the fit indices for the model in which trust is considered the antecedent of conflict were slightly better, both models fitted the data well. The interdependence of trust and conflict was further explored in a second longitudinal study (49 teams), and the results showed that trust emerging in the initial team interaction phases is a good predictor for the emergence of both task and relationship conflict in further stages of team development. (PsycINFO Database Record (c) 2010 APA, all rights reserved)