Thioethyl‐Porphyrazine/Nanocarbon Hybrids for Photoinduced Electron Transfer

A novel pyrene‐substituted thioethyl‐porphyrazine ( PzPy ) and the formation of supramolecular assembly with nanocarbons demonstrating photoinduced electron transfer ability are designed. As revealed by spectroscopic and electrochemical studies, PzPy displays wide spectral absorption in the visible range, charge separation upon photoexcitation, as well as bandgap and highest occupied/lowest unoccupied molecular orbital (HOMO/LUMO) energy values, matching the key requirements of organic optoelectronic. Moreover, the presence of a pyrene moiety promotes attractive interactions with π‐conjugated systems. In particular, theoretical calculations show that in the PzPy the HOMO and LUMO are localized on different positions of the molecule, i.e., the HOMO on the pyrene moiety and the LUMO on the macrocycle. Therefore, HOMO–LUMO excitation gives rise to a charge separation, preventing excitons recombination. Two kinds of noncovalent hybrid composites are prepared by mixing the PzPy with single‐wall carbon nanotubes (SWNTs) and graphene nanoflakes (GNFs), respectively, and used for photocurrent generation through charge transfer processes between PzPy and nanocarbons. Photoconduction experiments show photocurrent generation upon visible light irradiation of both PzPy /SWNT and PzPy /GNF composites (0.78 and 0.71 mA W^?1 at 500 nm, respectively), demonstrating their suitability for optoelectronic applications and light harvesting systems.     

An examination of people of color supervision dyads: Racial identity matters as much as race.

Considering the growing racial and ethnic diversity among supervisees, the number of clinical supervision dyads comprised of supervisees and supervisors of Color is likely to increase dramatically. Although extant research has focused on supervision that involves White supervisors paired with racial, ethnic, and linguistic minority supervisees, few authors have explored the supervisory dynamics between clinicians of color and supervisees of Color. This study used a qualitative analysis of structured survey responses provided by supervisees of Color to argue that racial identity (i.e., supervisors’ and supervisees’ psychological experiences of race), more than race is essential for managing the racial dynamics of supervisory dyads involving two people of Color. Using Helms Racial Identity Social Interaction Model (Helms, 1990, 1995), we use a directed content analysis of participants’ responses to demonstrate common themes that emerge when race is introduced into the supervision relationship. Based on supervisees’ reported experiences, implications for the practice of supervision involving people of Color are offered. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Urban adolescents' constructions of supports and barriers to educational and career attainment.

This study presents the educational and career goals and perceptions of supports and barriers related to these goals as described in semistructured interviews of 16 students from diverse racial and ethnic backgrounds attending 9th grade at an urban public high school in a large Northeastern city. Using consensual qualitative research (CQR) methodology (C. E. Hill et al., 2005), the authors identified categories and subcategories to students' perceptions of barriers and supports. The findings highlight students' understanding of how their proximal contexts serve potentially as both supports and barriers. Implications for educational and career interventions are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Audio watermarking scheme based on embedding strategy in low frequency components with a binary image

With the recent development of information technology and computer network, digital format of data has become more and more popular. However, a major problem faced by digital data providers and owners is protecting data from unauthorized copying and distribution. As a solution to the problem, digital watermark technology is now attracting attention as new method of protection against said unauthorized copying and distribution. The aim of the digital audio watermarking is to take prespecified data that carries certain information and hide it within the audio stream such that it is not audible to the human ear (i.e., transparent) but at the same time renders the file more resistant to removal (i.e., robust). In this paper, we propose a new method for embedding digital watermarks into audio signals in low frequency components, which method mitigates these and other related shortcomings. The proposed method uses the wavelet transform constructed by lifting-based wavelet transform (LBWT) in order to provide a fast implementation between watermark embedding and extraction parts. In the first stage of the proposed method, the original audio host signal is converted to a wavelet domain using LBWT. The signal is thus decomposed into low and high frequency components. Approximation coefficients correspond to low frequency components of the signal. Next, the watermark generated by pseudorandom numbers is embedded into wavelet approximation coefficients of the segmented host audio signal depending on the binary value of the binary image. The reason for embedding the watermark in the low frequency components is that these components' energy is greater than that of high frequency components in such a way that the watermark is inaudible; therefore, it should not alter the audible content and should not be easy to remove. The proposed method uses a binary image to decide whether or not the watermark generated by pseudorandom numbers is embedded in the audio host signal. To evaluate the performance of the proposed audio watermarking method, subjective and objective quality tests including bit error rate (BER) and signal-to-noise ratio (SNR) are conducted. The tests' results show that the proposed method yields a high recovery rate after attacks by commonly used audio data manipulations such as low-pass filtering, requantization, resampling and MP3 compression.     

Comparison of new activation functions in neural network for forecasting financial time series

In artificial neural networks (ANNs), the activation function most used in practice are the logistic sigmoid function and the hyperbolic tangent function. The activation functions used in ANNs have been said to play an important role in the convergence of the learning algorithms. In this paper, we evaluate the use of different activation functions and suggest the use of three new simple functions, complementary log-log, probit and log-log, as activation functions in order to improve the performance of neural networks. Financial time series were used to evaluate the performance of ANNs models using these new activation functions and to compare their performance with some activation functions existing in the literature. This evaluation is performed through two learning algorithms: conjugate gradient backpropagation with Fletcher–Reeves updates and Levenberg–Marquardt.     

An Omniphobic Spray Coating Created from Hierarchical Structures Prevents the Contamination of High-Touch Surfaces with Pathogens

Engineered surfaces that repel pathogens are of great interest due to their role in mitigating the spread of infectious diseases. A robust, universal, and scalable omniphobic spray coating with excellent repellency against water, oil, and pathogens is presented. The coating is substrate-independent and relies on hierarchically structured polydimethylsiloxane (PDMS) microparticles, decorated with gold nanoparticles (AuNPs). Wettability studies reveal the relationship between surface texturing of micro- and/or nano-hierarchical structures and the omniphobicity of the coating. Studies of pathogen transfer with bacteria and viruses reveal that an uncoated contaminated glove transfers pathogens to >50 subsequent surfaces, while a coated glove picks up 10⁴ (over 99.99%) less pathogens upon first contact and transfers zero pathogens after the second touch. The developed coating also provides excellent stability under harsh conditions. The remarkable anti-pathogen properties of this surface combined with its ease of implementation, substantiate its use for the prevention of surface-mediated transmission of pathogens.     

TiO(2) fibers enhance film integrity and photovoltaic performance for electrophoretically deposited dye solar cell photoanodes

Nanoparticulated TiO(2) fibers as one-dimensional long structures were introduced into TiO(2) P25 nanoparticle films using coelectrophoretic deposition. This prevented the usual crack formation occurring in wet coatings, and resulted in less porosity and higher roughness factor of the films that provided more favorable conditions for electron transport. The films used as the photoanode of a dye solar cell (DSC) produced 65% higher photovoltaic efficiency. TiO(2) fibers can be excellent binders in single-step, organic-free electrophoretic deposition of TiO(2) for DSC photoanode.     

Extending the Colloidal Transition Metal Dichalcogenide Library to ReS2 Nanosheets for Application in Gas Sensing and Electrocatalysis

Among the large family of transition metal dichalcogenides, recently ReS₂ has stood out due to its nearly layer‐independent optoelectronic and physicochemical properties related to its 1T distorted octahedral structure. This structure leads to strong in‐plane anisotropy, and the presence of active sites at its surface makes ReS₂ interesting for gas sensing and catalysts applications. However, current fabrication methods use chemical or physical vapor deposition (CVD or PVD) processes that are costly, time‐consuming and complex, therefore limiting its large‐scale production and exploitation. To address this issue, a colloidal synthesis approach is developed, which allows the production of ReS₂ at temperatures below 360 °C and with reaction times shorter than 2h. By combining the solution‐based synthesis with surface functionalization strategies, the feasibility of colloidal ReS₂ nanosheet films for sensing different gases is demonstrated with highly competitive performance in comparison with devices built with CVD‐grown ReS₂ and MoS₂. In addition, the integration of the ReS₂ nanosheet films in assemblies together with carbon nanotubes allows to fabricate electrodes for electrocatalysis for H₂ production in both acid and alkaline conditions. Results from proof‐of‐principle devices show an electrocatalytic overpotential competitive with devices based on ReS₂ produced by CVD, and even with MoS₂, WS₂, and MoSe₂ electrocatalysts.     

TAPAS: Trustworthy privacy-aware participatory sensing

With the advent of mobile technology, a new class of applications, called participatory sensing (PS), is emerging, with which the ubiquity of mobile devices is exploited to collect data at scale. However, privacy and trust are the two significant barriers to the success of any PS system. First, the participants may not want to associate themselves with the collected data. Second, the validity of the contributed data is not verified, since the intention of the participants is not always clear. In this paper, we formally define the problem of privacy and trust in PS systems and examine its challenges. We propose a trustworthy privacy-aware framework for PS systems dubbed TAPAS, which enables the participation of the users without compromising their privacy while improving the trustworthiness of the collected data. Our experimental evaluations verify the applicability of our proposed approaches and demonstrate their efficiency.     

Semantic Web and Social Web heading towards Living Documents in the Life Sciences

Rather than a document that is constantly being written as in the wiki approach, the Living Document (LD) is a document that also acts as a document router, operating by means of structured and organized social tagging and using existing ontologies. It offers an environment where users can manage papers and related information, share their knowledge with their peers and discover hidden associations amongst the shared knowledge. The LD builds upon both the Semantic Web, which values the integration of well-structured data, and the Social Web, which aims to facilitate interaction amongst people by means of user-generated content. In this vein, the LD is similar to a social networking system, with users as central nodes in the network, with the difference that interaction is focused on papers rather than people. Papers, with their ability to represent research interests, expertise, affiliations, and links to web based tools and databanks, are the central axis for interaction amongst users. To support this, we have also implemented a novel web prototype that enables researchers to accomplish three activities central to the Semantic Web vision: organizing, sharing and discovering. Availability: http://www.scientifik.info/livingdocument.