In situ measurement of GaN film photoluminescence under plasma etching

This work focuses on an improved method that enables us to measure in situ GaN film photoluminescence (PL) under Ar or N₂ plasma etching. Although the background signal is large and increases with bias voltage, the GaN PL can be obtained after subtraction of this background from the total luminescence. Moreover, after plasma etching, the intensities of the near-band-edge and the yellow luminescence decrease significantly. It is suggested that this behaviour is strongly related to the heavy plasma-induced damage, which includes non-radiative defects and deep-level defects, such as Ga vacancies and/or C impurities.     

Characterization of Al/n-ZnO/p-Si/Al structure with low-cost solution-grown ZnO layer

We report the fabrication of Al/n-ZnO/p-Si/Al diode structures with a flower-like ZnO layer. The average grain size, microstrain and dislocation density in the ZnO layer were determined as 25?nm, 1.55?×?10^?3 and 3.23?×?10¹³?cm^?2, respectively. From absorption spectra, the optical band gap was found to be ～3.17?eV. A red shift was attributed to non-stoichiometry arising from Zn⁺² ions substituting for oxygen vacancies. The ideality factor was determined as 1.55. The barrier height was calculated as 0.71?eV from I–V characteristics and 0.73?eV using the Norde plots.     

A comparative study on GaN luminescence under/after inductively coupled plasma exposure

GaN luminescence, induced by ultraviolet light under/after inductively coupled plasma exposure, has been measured in situ and ex situ. After the plasma exposure, both near-band edge (NBE) and yellow luminescence (YL) intensities decrease. The decay times of NBE and YL in the in situ measurement are shorter than those of the ex situ measurement on account of the temperature rise induced by the plasma. On the other hand, with increasing plasma power, the decay times decrease. It is considered that this decrease is strongly related to non-radiative defects introduced by the Ar plasma. The results suggest that in situ photoluminescence monitoring can be used to reveal plasma-induced damage at GaN surfaces.     

The Moderating Role of Intergroup Contact in Race Composition,Perceived Similarity,and Applicant Attraction Relationships

Purpose

This study investigated the moderating effect of intergroup contact on the relationship between the race composition of organizational representatives, perceived similarity, and minority applicant attraction.

Design/Methodology/Approach

344 minority Malaysian-Chinese university students read a job advertisement that varied the racial composition of organizational representatives (100 % Malay or 50 % Malay–50 % Chinese or 100 % Chinese). Of these participants, 161 were Malaysian-Chinese in Malaysia (high intergroup contact location) and 183 were Malaysian-Chinese in Australia (low intergroup contact location). After reading the advertisement, participants responded to a series of scale items (e.g., perceived surface-level similarity, perceived deep-level similarity, and applicant attraction).

Findings

Results showed that the effect of race composition on attraction was stronger for minority participants in Australia than for minority participants in Malaysia. Perceived deep-level similarity mediated this moderated relationship.

Implications

The study findings suggest that organizations should include minority representatives in their recruitment advertising to attract minority applicants, particularly to attract minorities in locations with few opportunities for intergroup contact.

Originality/Value

By testing the mediating effects of perceived surface-level and deep-level similarity, this study contributes to our understanding of the mechanism linking the interaction between race composition and location with applicant attraction.

     

High-efficiency single-layer organic light-emitting diode based on green fluorescent protein

We have fabricated a molecular organic light-emitting device comprising indium–tin oxide/a molecular organic layer/aluminum in which the organic layer is a green fluorescent protein. The device exhibits peak external quantum and power efficiencies of 8?±?0.2% and 13?±?0.7?lm?W?^??1 at a current of J?=?1.5?A?m^?2, respectively. In addition, the turn-on voltage is 2.5?V for 1?cd?m^?2 and the maximum luminance achieved is 1275?cd?m^?2. This good performance can be explained by the presence of singlet-excited states, leading to a high internal efficiency.     

Interrelated emission and spin–spin relaxation feature mediated by VO+ defects in Gd2O3 nanorods subjected to swift ion impact

We report on the manifestation and interconnected photoluminescence and electron paramagnetic resonance responses in gadolinium oxide (Gd₂O₃) nanorods subjected to 80 MeV carbon ion irradiation. On increasing the irradiation fluence between 1 × 10¹¹ and 3 × 10¹² ions/cm², the emission associated with neutral oxygen vacancies (V_Ox), positioned at ~350 nm, undergoes a steady increase compared to that associated with singly charged vacancies (V_O⁺), located at ~414 nm. The enhancement of spin–spin relaxation time (τ_ss) is ascribed to a substantial changeover from V_O⁺ to V_Ox defects with irradiation, the former being recognized as the major contributor to paramagnetic centres. Interconnected luminescence and spin–spin relaxation could provide insight for making advanced nanophosphors and spin valve elements.     

Retention and thermal desorption of helium in pure tungsten

Tungsten (W) is cited as a candidate first-wall material in fusion reactors owing to its outstanding thermal properties and erosion resistance. An important issue is that the energetic isotopes of hydrogen, tritium (T) and deuterium (D) and helium (He) particles damage the surface of W in fusion reactors. He particles cause more notable damage than D or T because the binding energy of defects and He is larger than that of defects and D or T. In this study, well-annealed W specimens were implanted with 5 keV He ions at room temperature and irradiation dosages of 1.0 × 10²⁰ and 2.5 × 10²¹ ions/m². Then, thermal desorption spectroscopy analysis was performed by heating the samples to 1973 K at a ramping rate of 0.5 K/s. Thermal desorption of He in the sample irradiated with a low dosage occurred at 1400 and 1960 K, whereas that in the sample irradiated with a high dosage occurred at 740, 1050 and 1500 K. According to the microstructures observed using transmission electron microscopy, both peaks in the former case were attributed to He de-trapping from irradiation to nduced helium-vacancy clusters of different sizes, whereas the peaks in the latter case were attributed to He de-trapping from surface defects, irradiation-induced dislocation loops and tiny helium-vacancy clusters, respectively.     

Visual search for arbitrary objects in real scenes

How efficient is visual search in real scenes? In searches for targets among arrays of randomly placed distractors, efficiency is often indexed by the slope of the reaction time (RT) × Set Size function. However, it may be impossible to define set size for real scenes. As an approximation, we hand-labeled 100 indoor scenes and used the number of labeled regions as a surrogate for set size. In Experiment 1, observers searched for named objects (a chair, bowl, etc.). With set size defined as the number of labeled regions, search was very efficient (~5 ms/item). When we controlled for a possible guessing strategy in Experiment 2, slopes increased somewhat (~15 ms/item), but they were much shallower than search for a random object among other distinctive objects outside of a scene setting (Exp. 3: ~40 ms/item). In Experiments 4–6, observers searched repeatedly through the same scene for different objects. Increased familiarity with scenes had modest effects on RTs, while repetition of target items had large effects (>500 ms). We propose that visual search in scenes is efficient because scene-specific forms of attentional guidance can eliminate most regions from the “functional set size” of items that could possibly be the target.     

Experimental observation of the dislocation walls in heterostructures with two interfaces: Ge/Ge0.5Si0.5 10 nm/Si(001) as an example

High-resolution electron microscopy (HREM) at the atomic scale has been applied to study the edge dislocation redistribution between interfaces in Ge/Ge_0.5Si_0.5/Si(0?0?1) heterostructures. Our results provide a direct explanation that plastic relaxation of the GeSi buffer layer proceeds owing to motion of Lomer-type dislocation complexes consisting of a pair of complementary 60° dislocations with the ends of the {1?1?1} extra planes being located at a distance of ~2–12 interplanar spacings from each other. It is demonstrated that edge dislocations belonging to the upper and lower interfaces become arranged one under the other and dislocation walls are formed. The distributions of tension and compression in the [0?0?1] direction between two edge dislocations, obtained by processing the HREM image, testify to superposition of strain fields.     

Self-diffusion activation energies in α-Al2O3 below 1000°C – measurements and molecular dynamics calculation

Results from impedance spectroscopy measurements at temperatures between 400 and 1000°C, for single crystal and highly pure and dense polycrystalline α-Al₂O₃ samples with well-defined grain size, are compared with that from molecular dynamics calculation. Between 650 and 1000°C, the measured activation energy for conductivity is 1.5?eV for the single crystal, and increases from 1.6 to 2.4?eV as the grain size decreases from 15 to 0.5?µm. The molecular dynamics calculation leads to the conclusion that the self-diffusion activation energy is about 1.5?eV for O and 1.0?eV for Al in single crystal α-Al₂O₃. The much higher mobility of O ions makes the O ions responsible for the conductivity of the single crystal oxide. It seems that the grain boundary leads to an increase in the activation energy. However, the quantitative influence of grain boundary still needs to be explained. Between 400 and 650°C, the measured activation energy is about 1.0?eV and independent of the grain size.     

Iron in solution with aluminum matrix after non-equilibrium processing: an atom probe tomography study

In this paper, we report on the influence of rapid solidification and severe plastic deformation on the solid solubility of Fe in Al. Atom probe tomography, for the first time, was performed on fine (3–4 μm diameter) and coarse (~100 μm) as-atomised Al-5 at.% Fe powder and cryomilled Al-5 at.% Fe powder. The atomised powders exhibited negligible Fe in solution with Al, whereas the cryomilled powder contained ~2 at.% Fe in solution. Moreover, our results suggest that severe plastic deformation is preferable to atomisation/rapid solidification for increasing the non-equilibrium solid solubility of Fe in Al.     

The influence of perceived family support on post surgery recovery

The objective of this work was to investigate the possible relationship between perceived family support, levels of cortisol and post surgery recovery. The study sample comprised 42 patients that were due to undergo open cholecystectomy surgery in a Regional Health Authority Reference Centre of the Autonomous Community of Extremadura in Spain. The FACES-II questionnaire was used for the evaluation of perceived family support and to measure the three fundamental dimensions of perceived family behaviour: cohesion, adaptability and family type. The day before surgery, a sample of saliva was taken from each subject in order to determine the level of cortisol. Results showed a clear relationship between family support and recovery. Patients with higher scores on the Cohesion Scale demonstrated better post surgery recovery (F = 8.8; gl = 40; p = .005). A relationship between levels of cortisol, perceived family support and recovery was also revealed. Patients with lower scores on the Cohesion scale and higher cortisol levels demonstrated poorer post surgery recovery (F = 10.96; gl = 40; p = .006). These results are coherent with other studies that have highlighted the beneficial effects of perceived family support on mental and physical health.     

One-step synthesis of bulk quantities of graphene from graphite by femtosecond laser ablation under ambient conditions

Bulk synthesis of few-layer graphene (FLG) for industrial applications still remains a challenge for researchers. Here, we report a very simple technique for bulk synthesis of FLG by femtosecond laser ablation of graphite powder suspended in ethanol without the requirement of a controlled environment. Graphite powder, with an average particle size <20 μm, was suspended uniformly in ethanol and ablated at room temperature using fs pulses (wavelength ~800 nm and an input beam diameter ~8 mm) followed by ultrasonication to obtain FLG with a lateral size of ~1 μm. Raman spectroscopy and high-resolution transmission electron microscopy data confirmed the nature and morphology of the FLG. The quality and number of layers in the FLG could be controlled by tuning the laser parameters.     

Worry and rumination: do they prolong physiological and affective recovery from stress?

Background: Anxiety and depression have been linked to repetitive negative self-regulation styles in the form of worry and rumination respectively. Following predictions of the metacognitive model [Wells, A., & Matthews, G. (1994). Attention and emotion: A clinical perspective. Hove: Erlbaum], the current study compared the effect on recovery from stress of three strategies: worry, rumination, and distraction using a stress exposure paradigm. It was predicted that worry and/or rumination would be associated with delayed recovery on physiological and/or self-report indices when compared to distraction.

Method: Fifty-four participants were randomly assigned to one of the self-regulation conditions and then completed a modified version of the Trier Social Stress Test [TSST; Kirschbaum, C., Pirke, K. M., & Hellhammer, D. H. (1993). The “TSST” – A tool for investigating psychobiological stress responses in a laboratory setting. Neuropsychobiology, 28, 76–81. doi:10.1159/000119004]. Skin conductance and negative affect (NA) measurements were obtained at six different time points.

Results: Skin conductance indicated a prolonged recovery in the rumination condition when compared with the distraction condition. Individuals in the worry condition reported an immediate-delayed recovery from stress marked by higher NA scores in comparison to the distraction condition.

Conclusions: These findings may provide important insights into the effects of different forms of repetitive negative thinking on physiological and psychological recovery from stress. The different response patterns observed are discussed within the context of the metacognitive model.     

High-pressure torsion of metastable austenitic stainless steel at moderate temperatures

We subjected samples of a 304 metastable austenitic stainless steel to high-pressure torsion (HPT) in the temperature range of 303–573 K, (i.e. at different austenite stabilities), to examine their microstructures and mechanical properties. HPT processing at room temperature led to the formation of a lamellar microstructure with austenitic and martensitic phases, of which sizes were characterised by prior austenite grains, whereas HPT processing at moderate temperatures produced nanostructured austenite grains through mechanical twinning. The nanostructured 304 steel with an average grain size of ~70 nm exhibited a fine balance between tensile strength (~1.7 GPa) and reduction of area (~55%).     

Developmentally Adapted Cognitive Processing Therapy for Adolescents Suffering from Posttraumatic Stress Disorder after Childhood Sexual or Physical Abuse: A Pilot Study

Although childhood sexual abuse and childhood physical abuse (CSA and CPA) have severe psychopathological consequences, there is little evidence supporting psychotherapeutic interventions for adolescents who have experienced CSA or CPA. To provide a treatment tailored to the specific needs of adolescents suffering from abuse-related posttraumatic stress disorder (PTSD), we modified Cognitive Processing Therapy (CPT) by adding new treatment modules and changing the therapy setting. To evaluate the feasibility and efficacy of Developmentally Adapted CPT (D-CPT), we treated 12 adolescents suffering from PTSD secondary to CSA or CPA. Patients were assessed prior to treatment (t0), post-treatment (t1), and 6 weeks after treatment (t2). Assessments included the Clinician-Administered PTSD Scale (CAPS), the UCLA PTSD Index (UCLA), the Children’s Depression Inventory (CDI), the Adolescent Dissociative Experiences Scale (A-DES), and the Borderline Symptom List (BSL-23). MANOVAs revealed that posttraumatic stress measurements and associated symptom measurements significantly differed across time points. When comparing t0 with t2, Cohen’s d was large with respect to the CAPS scores (d = 1.45, p < .001) and the UCLA scores (d = 1.91, p < .001). Cohen’s d had a medium magnitude with respect to the CDI scores (d = .78, p < .001), the A-DES scores (d = 0.64, p < .05), and the BSL-23 scores (d = 0.74, p < .01). D-CPT has the potential to reduce PTSD symptoms and comorbid psychopathology in adolescents with histories of CSA or CPA.     

Defect analysis of Fe3(Al1– x Si x ) alloys by positron-lifetime spectroscopy

The recovery behaviour of vacancy-type defects created at 1000°C in Fe₃(Al_{1– x} Si _x ) alloys has been investigated by positron-lifetime measurements in samples cooled to room temperature by water quenching, air quenching and furnace cooling. In addition, a set of samples was aged for one week at 520°C. After water quenching, measurements reveal a high concentration of thermal vacancies, and from the decrease of the average positron lifetime it is inferred that vacancy recovery is strongly composition-dependent. Greater decreases of the positron lifetime were found for Si-rich samples, suggesting diffusion enhancement as the Si concentration increases. For the Fe₃Al alloy, the retained vacancy concentration depends strongly on the cooling rate. This is related to atomic ordering and a rebuilding of the D0₃ structure.     

Effects of cognitive-behavioural therapy on anxiety,depression and condom use in people with HIV in Mexico City: a pilot study

Anxiety and depression in people living with HIV (PLWH) are negatively associated with healthy sexual behaviours. We pilot-tested a Cognitive-Behavioural Therapy (CBT)-based intervention to reduce anxiety and depression, aimed to increase serostatus disclosure to sexual partners, quality of sexual life (QoSL) and condom use. The study had a single-case experimental design (AB) with follow-up measures. Eleven PLWH with moderate/severe anxiety/depression received six-module CBT intervention delivered in ten one-hour individual weekly sessions. Anxiety, depression, consistent/correct condom use and QoSL were measured. Depression and anxiety decreased after the intervention (depression baseline [BL] Mdn = 21, final [F] Mdn = 3, z = -2.934, p = .003; anxiety BL Mdn = 30, F Mdn = 4, z = -2.941, p = .003). QoSL improved (BL Mdn = 28, F Mdn = 13, z = -2.625, p = .009), along with participants’ ability to use condoms (57.14 vs.100, z = -2.937, p = .003). Effect size was large, changes were maintained at follow-up measurements. The CBT intervention had positive effects in reducing anxiety and depression, which could facilitate the acquisition of healthy sexual behaviours. Further studies are important to clarify the benefits of targeting emotional variables to improve wellbeing and prevention behaviours in PLWH.     

What can boys and girls do? Preschoolers’ perspectives regarding gender roles across domains of behavior

Previous research has examined at what age and in what contexts males and females develop gender-congruent stereotypes. Research indicates that social experience may provide a great influence on the presence of such stereotypes, but this is likely influenced by the development of gender schemas. The current study interviewed 99 children (3–6.5 years) in a sub-rural Midwestern university community. Females (N = 51, M _age = 4.6, SD = 0.73) and males (N = 48, M _age = 4.6, SD = 0.82) were individually asked who—boys, girls, or both—can do particular (1) occupations, (2) activities, (3) aggressive behaviors, and (4) prosocial behaviors. Generally, males tended to express holding no stereotypic beliefs, indicating gender-congruent expectations for only 2 items in one of the domains; however, females expressed multiple stereotypic beliefs for each of the four contexts. Social and cognitive explanations for these phenomena are discussed. The current study is an important addition to the existing literature in that preschool teachers and parents alike might be able to assist children to better develop activities and behavioral habits such that gender-related stereotypes fail to develop.