Low temperature growth and planar doping of ZnSe in a plasma-stimulated LP-MOVPE system

In a low-pressure metalorganic vapor phase epitaxy process, we used dc-plasma activated nitrogen to dope ZnSe, grown with ditertiarybutylselenide and dimethylzinc-triethylamine. The nitrogen concentration of up to 2 × 10¹⁸ cm⁻³ in the doped layers can be adjusted by the growth temperature, the dc-plasma power, and the N₂ dopant flow. Due to the high n-type background carrier concentration of the order of 10¹⁷ cm⁻³ in undoped samples, the doped layers show n-type conductivity or were semi-insulating because of an additional compensation by hydrogen incorporated with a concentration of the order of 10¹⁸ cm⁻³. A planar doping scheme was applied to reduce this hydrogen incorporation by one order of magnitude, although H₂ was used as carrier gas.     

Strain Control of Oxygen Vacancies in Epitaxial Strontium Cobaltite Films

The ability to manipulate oxygen anion defects rather than metal cations in complex oxides can facilitate creating new functionalities critical for emerging energy and device technologies. However, the difficulty in activating oxygen at reduced temperatures hinders the deliberate control of important defects, oxygen vacancies. Here, strontium cobaltite (SrCoO_x) is used to demonstrate that epitaxial strain is a powerful tool for manipulating the oxygen vacancy concentration even under highly oxidizing environments and at annealing temperatures as low as 300 °C. By applying a small biaxial tensile strain (2%), the oxygen activation energy barrier decreases by ≈30%, resulting in a tunable oxygen deficient steady‐state under conditions that would normally fully oxidize unstrained cobaltite. These strain‐induced changes in oxygen stoichiometry drive the cobaltite from a ferromagnetic metal towards an antiferromagnetic insulator. The ability to decouple the oxygen vacancy concentration from its typical dependence on the operational environment is useful for effectively designing oxides materials with a specific oxygen stoichiometry.     

Information function of empathic emotion: Learning that we value the other's welfare.

Empathic feelings arise when a person values another's welfare and perceives the other to be in need. As a result, level of empathic response can be used to infer how much one values the welfare of a person in need. Four experiments were conducted to test these ideas. Experiments 1 and 2 revealed that a similarity manipulation led to increased valuing of a similar person's welfare and, in turn, to increased empathy when this person was in need. Experiments 3 and 4 revealed that direct manipulations of empathy (perspective-taking instructions, or false physiological arousal feedback) led to increased empathy and, in turn, to increased valuing of the welfare of the person in need. Once induced, this valuing was a relatively stable disposition; it remained even after empathy had declined. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Trace explosive detection in aqueous samples by solid-phase extraction ion mobility spectrometry (SPE-IMS)

Law enforcement agencies use ion mobility spectrometers for the detection of explosives, drugs of abuse, and chemical warfare agents. Ion mobility spectrometry (IMS) has the advantages of short analysis times, detections in the parts per billion concentrations, and high sensitivity. On-site environmental analysis of explosives or explosive residues in water is possible with ion mobility spectrometers. Unfortunately, the direct analysis of low levels of explosives in water is difficult. Extraction provides a method for pre-concentrating the analytes and removing interferents. Coupling solid-phase extraction (SPE) with IMS is useful for the identification of trace amounts of explosives in water. Commercially available SPE disks were used. After extraction, the sample disk is inserted into the ion mobility spectrometer, where the analytes are thermally desorbed from the disk. Concentrations as low as one part per trillion were detected with a Barringer Ionscan 350. An external computer and acquisition software (LabVIEW, National Instruments) were used to collect data. SIMPLISMA (SIMPLe-to-use-Interactive Self-modeling Mixture Analysis) was applied to the data to resolve features that vary with respect to time.     

Second-order contrast based on the expectation of effort and reinforcement.

Pigeons prefer signals for reinforcement that require greater effort (or time) to obtain over those that require less effort to obtain (T. S. Clement, J. Feltus, D, H. Kaiser, & T. R. Zentall, 2000). Preference was attributed to contrast (or to the relatively greater improvement in conditions) produced by the appearance of the signal when it was preceded by greater effort. In Experiment 1, the authors of the present study demonstrated that the expectation of greater effort was sufficient to produce such a preference (a second-order contrast effect). In Experiments 2 and 3, low versus high probability of reinforcement was substituted for high versus low effort, respectively, with similar results. In Experiment 3, the authors found that the stimulus preference could be attributed to positive contrast (when the discriminative stimuli represented an improvement in the probability of reinforcement) and perhaps also negative contrast (when the discriminative stimuli represented reduction in the probability of reinforcement). (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Immorality from empathy-induced altruism: When compassion and justice conflict.

Results of 2 experiments supported the proposal that empathy-induced altruism can lead one to act in a way that violates the moral principle of justice. In each experiment, participants were asked to make an allocation decision that affected the welfare of other individuals. Participants who were not induced to feel empathy tended to act in accord with a principle of justice; participants who were induced to feel empathy were significantly more likely to violate this principle, allocating resources preferentially to the person for whom empathy was felt. High-empathy participants who showed partiality agreed with other participants in perceiving partiality to be less fair and less moral (Experiment 1). Overall, results suggested that empathy-induced altruism and the desire to uphold a moral principle of justice are independent prosocial motives that sometimes cooperate but sometimes conflict. Implications of this independence are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Degradation of flame retardance: A comparison of ethylene-vinyl acetate and low-density polyethylene cables with two different metal hydroxides

The durability of flame retardancy is a challenge for cables over long lifetimes. The degradation of flame retardance is investigated in two kinds of exposures, artificial weathering and humidity. In this basic study, typical mineral flame retardants in two polymers frequently used in cable jackets are investigated to get the fundamental picture. Aluminum hydroxide (ATH) and magnesium hydroxide (MDH) are compared in ethylene-vinyl acetate (EVA), and further in EVA and linear low-density polyethylene (LLDPE) cables containing the same ATH. The changes in chemical structure at the surface are studied through attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), the formation of cracks, and changes in color are investigated. The cone calorimeter and a bench scale fire testing cable module are utilized to evaluate the fire behavior of the cables. Although the flame retardancy deteriorated slightly, it survived harsh exposure conditions for 2000 h. Compared to EVA/MDH and LLDPE/ATH, the fire behavior of EVA/ATH is the least sensitive. Taken together, all of the results converge to estimate that there will be no problem with flame retardancy performance, for materials subjected to natural exposure for several years; the durability of fire retardancy is questionable for longer periods, and thus requires further investigation.     

Variation among plant species in pollutant removal from stormwater in biofiltration systems

Biofiltration systems use vegetation to improve efficiency of pollutant removal from stormwater, but little is known of how plants vary in their capacity to improve biofilter effectiveness. We used a pot trial of 20 Australian species to investigate how species vary in the removal of pollutants from semisynthetic storm water passing through a soil filter medium. Effluent levels of total suspended solids (TSS), Al, Cr, Cu, Pb and Zn were similarly low for vegetated and non-vegetated soils, with reduction to <1-12% of levels in the stormwater input. N and P effluent concentrations were generally lower from vegetated than non-vegetated soils, but total N increased on average in effluent of both vegetated and non-vegetated soils relative to stormwater input. Effluent concentrations varied 2-4-fold among species for TSS, total N and P, total dissolved N (TDN), organic nitrogen and Cu, to more than 20-fold for NOx, NH4+, Mn, Pb and Fe. Species also varied markedly in pollutant removal per root mass (a means of standardising for plant size), with 18-50-fold variation among species in effluent concentrations of total P and N, TDN and organic N, to >150-fold variation in NOx and NH4+. Hence, choice of plant species may have marked effects on biofilter effectiveness.     

Adolescent personality as a prospective predictor of parenting: An interactionist perspective.

This study examined personality during adolescence as a predictor of later parenting of toddler-aged offspring. On the basis of empirical research on the timing of parenthood and the interactionist model (Conger & Donnellan, 2007), we examined age at parenthood and family socioeconomic status (SES) as mediators of the relation between personality and parenting. Participants were 228 emerging adults from an ongoing longitudinal study of the transition to adulthood. Later entry into parenthood and higher SES accounted for the association between personality characteristics and lower levels of harsh parenting and higher levels of positive parenting. Consistent with the interactionist model, both personality characteristics and SES-linked variables were related to interpersonal processes in families. The findings suggest that promoting adaptive personality traits during childhood and adolescence may help delay early entry into parenthood, promote higher SES, and, indirectly, foster more positive parenting of young children. (PsycINFO Database Record (c) 2010 APA, all rights reserved)