Eco-friendly synthesis of large band gap ZnO nanoparticles by trisodium citrate: investigation of annealing effect on structural and optical properties

In this study, large band gap zinc oxide nanoparticles (ZnO-NPs) were prepared by a facile, cost-effective, and eco-friendly co-precipitation method in aqueous solutions. Trisodium citrate was employed as a green and bio-safe complexing agent for zinc ions without using ammonia and/or any organic solution. The annealing effect on crystal structure, morphology, particle size, composition, UV absorption, and fluorescence (FL) properties of the synthesized ZnO-NPs was evaluated using various techniques. The UV–Visible absorption spectra of the ZnO-NPs showed a strong absorption peak in the UV-C region with a wide band gap energy of 4.2–4.4 eV. Field emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM) images demonstrated fine spherical particles with approximate diameters of 20–50 nm. The average hydrodynamic diameter and zeta potential values of the as-prepared and the annealed ZnO-NPs in deionized water were 28.2 nm, ? 32.4 mV, 38.9 nm, and ? 16.1 mV, respectively. The FL and UV–Visible results illustrated that the annealing could considerably influence the emission and absorption spectra of the samples in the UV region. The FL and EDX results revealed that the annealing affects the composition, defect points, and states population in the crystal structure of the ZnO-NPs. Practical experiments of exposing the samples to UV radiation and the FL measurements indicated that the ZnO-NPs were sensitive to the excitation wavelengths, therefore, they have potential application in fabricating various types of UV sensors and filters (blockers), as well as photocatalytic activities.

     

Interactive publication: The document as a research tool

The increasing prevalence of multimedia and research data generated by scientific work affords an opportunity to reformulate the idea of a scientific article from the traditional static document, or even one with links to supplemental material in remote databases, to a self-contained, multimedia-rich interactive publication. This paper describes our concept of such a document, and the design of tools for authoring (Forge) and visualization/analysis (Panorama). They are platform-independent applications written in Java, and developed in Eclipse¹ using its Rich Client Platform (RCP) framework. Both applications operate on PDF files with links to XML files that define the media type, location, and action to be performed. We also briefly cite the challenges posed by the potentially large size of interactive publications, the need for evaluating their value to improved comprehension and learning, and the need for their long-term preservation by the National Library of Medicine and other libraries.     

Predicting sea-level variations at the Cocos (Keeling) Islands with artificial neural networks

Sea-level variations affect the construction and management of coastal structures, near-shore navigation, coastal rivers’ hydrological regime, and coastal tourism. Estimates of sea-level with hours-to-days warning times are especially important for low-lying regions, such as the Cocos (Keeling) Islands in the Indian Ocean. This study employs the technique of artificial neural networks to predict sea-level variations with warning times from 1 h to 5 days on the basis of hourly tide gauge observations. The data from the Cocos (Keeling) Islands SEAFRAME tide station for the period from 1992 to 2003 were used here. Feed-forward three-layered artificial neural networks were implemented to simulate sea level. The proposed neural methodology demonstrated reliable results in terms of the correlation coefficient (0.85–0.95), root mean square error (80–100 mm), and scatter index (0.1–0.2) when compared with actual observations. Therefore, the proposed methodology could be successfully used for site-specific forecasts.     

Enhancing social communication of children with high-functioning autism through a co-located interface

This study evaluated the effectiveness of a 3-week intervention in which a co-located cooperation enforcing interface, called StoryTable, was used to facilitate collaboration and positive social interaction for six children, aged 8–10 years, with autistic spectrum disorder (ASD). The intervention focused on exposing pairs of children to an enforced collaboration paradigm while they narrated a story. Pre- and post-intervention tasks included a “low technology” version of the storytelling device and a non storytelling play situation using a free construction game. The outcome measure was a structured observation scale of social interaction. Results demonstrated progress in three areas of social behaviors. First, the participants were more likely to initiate positive social interaction with peers after the intervention. Second, the level of shared play of the children increased from the pre-test to the post-test and they all increased the level of collaboration following the intervention. Third, the children with ASD demonstrated lower frequencies of autistic behaviors while using the StoryTable in comparison to the free construction game activity. The implications of these findings are discussed in terms of the effectiveness of this intervention for higher functioning children with ASD.     

Questioning the model minority: Studies of Asian American academic performance.

The current paper reviews literature on the academic performance of Asian Americans with a critical eye toward understanding the influence of discrimination on this process. Specifically, this study seeks to understand the extent to which researchers have gathered sufficient knowledge to dispel “conventional knowledge” of Asian Americans as model minorities. We questioned the extent to which studies explicitly measured student performance as a product of individual effort and Asian cultural influences, while simultaneously measuring the impact of exposure to discrimination. We present a review of studies on Asian American academic performance published 1990–2008. Our analysis suggests that social science research has continued to perpetuate the stereotype of Asian Americans as a “model minority.” The majority of the reviewed studies did not differentiate among Asian American ethnic and generational groups. These studies also tended to infer culture as an explanation for the high achievement of Asian Americans without examining the impact of sociopolitical factors, such as racial discrimination. In fact, many of the reviewed studies reported that Asian Americans were deficient relative to Whites on attributes thought to be related to culture (e.g., personality characteristics, parenting behaviors) while finding that they achieved academically at levels similar to or higher than Whites. Finally, the majority of these studies have not used culturally appropriate methods to test their hypotheses and research questions. Thus, we recommend that studies embrace emic/population-specific and sociopolitical (Sasao & Sue, 1993) approaches to understand and explore factors that contribute to academic achievement in this group. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Cognitive-Behavioral Analysis System of Psychotherapy as a Maintenance Treatment for Chronic Depression.

Although the efficacy of maintenance pharmacotherapy for the prevention of recurrence in major depressive disorder (MDD) is well documented, few studies have tested the efficacy of psychotherapy as a maintenance treatment. The authors examined the efficacy of the cognitive-behavioral analysis system of psychotherapy (CBASP) as a maintenance treatment for chronic forms of MDD. Eighty-two patients who had responded to acute and continuation phase CBASP were randomized to monthly CBASP or assessment only for 1 year. Significantly fewer patients in the CBASP than assessment only condition experienced a recurrence. The 2 conditions also differed significantly on change in depressive symptoms over time. These findings support the use of CBASP as a maintenance treatment for chronic forms of MDD. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Detection of discoloration in thermally processed blue crab meat

This study objectively and quantifiably examined the effect of a series of factors on blue crab meat discoloration. Factors explored include heating process, animal harvest location, and position of meat within a container. A Spectrogard colorimeter was used to collect visual reflectance spectra between 380 and 720 nm. Meat degree of coloration was characterised objectively and rapidly by using lightness (L), red–green (a) and yellow–blue (b) colour values. Results showed that meat became darker with increasing heating process; crab harvest location had significant effect on the lightness of the flesh; and meat that is located in the bottom of a can was darker than that in the top. This study will serve as a baseline for the development of a coloration quality control system. © 1999 Society of Chemical Industry     

Structure of polyethylene after pulse ion beam treatment

Pulse ion beam treatment was employed for polyethylene (PE) surface modification. Ultraviolet, infrared (IR), IR–attenuated total reflection spectroscopy (IR–ATR), and X-ray photoelectron spectroscopy methods, as well as wetting angle measurement, were used for the analysis of PE structural changes. Theoretical calculations and experimental data showed treated PE surfaces to have a layered structure. It was found that the upper layer contains various products of PE oxidation and the lower layer contains products of PE decomposition, that is, condensed aromatic structures. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 69: 1071–1077, 1998     

Directed evolution of RuBisCO hypermorphs through genetic selection in engineered E.coli

The Calvin Cycle is the primary conduit for the fixation of carbon dioxide into the biosphere; ribulose 1,5-bisphosphate carboxylase/oxygenase (RuBisCO) catalyzes the rate-limiting fixation step. Our goal is to direct the evolution of RuBisCO variants with improved kinetic and biophysical properties. The Calvin Cycle was partially reconstructed in Escherichia coli; the engineered strain requires the Synechococcus PCC6301 RuBisCO for growth in minimal media supplemented with a pentose. We randomly mutated the gene encoding the large subunit of RuBisCO (rbcL), co-expressed the resulting library with the small subunit (rbcS) and the Synechococcus PCC7492 phosphoribulokinase (prkA), and selected hypermorphic variants. The RuBisCO variants that evolved during three rounds of random mutagenesis and selection were over-expressed, and exhibited 5-fold improvement in specific activity relative to the wild-type enzyme. These results demonstrate a new strategy for the artificial selection of RuBisCO and other non-native metabolic enzymes.     

延安市区公众暴露环境电磁辐射测量及其分析

随着科学技术的发展，电气电子设备应用越来越广泛，空间辐射功率也越来越大，空间电磁场强度急剧增加。通过利用PMM8053P非选频式电磁辐射分析仪和方格法对延安市市区公众暴露电磁辐射的综合场强进行的实地测量，给出了延安市区公众暴露环境电磁辐射的分布状况，并依据国家相关标准对测量结果进行了分析讨论。