Defects and Charge Transport in β-Ta2O5: I, Analysis of the Conductivity Observed in Nominally Pure β-Ta2O5

Simple ionic defect theory has not been successful in describing the observed defect and transport behavior in β-Ta₂O₅. The available data were reviewed, and a revised model is proposed which more adequately describes the defect behavior of nominally pure or lightly doped β-Ta₂O₅.     

Electrode reaction mechanisms for the reduction of tert-butyl peracetate, lauryl peroxide and dibenzoyl peroxide

The reduction of tert-butyl peracetate, lauryl peroxide and dibenzoyl peroxide has been investigated at platinum and glassy carbon electrodes in DMF. It is known from the studies of Maran et al. that peroxides reduction mechanisms generally involve at first a slow electron transfer concerted with the scission of the peroxide bond. Then the radical produced at the electrode is immediately reduced, which leads to a two electrons consumption. Similar results were obtained in this study for tert-butyl peracetate, lauryl peroxide and dibenzoyl peroxide. Besides, the determination of the number of electrons involved in the reduction at different time scales gave a number of two for lauryl peroxide, dibenzoyl peroxide, tert-butyl peroxybenzoate and di-tert-butyl peroxide and showed that this transfer is followed, in the case of tert-butyl peracetate, by a subsequent chemical reaction consuming a part of the substrate.     

Characterization of planar waveguides obtained by proton exchange in lithium iodate

Due to its non-linear optical properties, lithium iodate is commonly used in optical devices. By proton exchange, performed by immersing z-cuts LiIO₃ single crystals in a molten hydrated nitrate salt, we formed a solid solution Li_1−xH_xIO₃ layer close to the surface. This modification of the structure increases the refractive index so that a waveguide is created. The index profile obtained by m-lines spectroscopy combined with structure characterization by μ-Raman and X-ray diffraction experiments allows us to describe the diffusion process of hydrogen in LiIO₃.     

Density-viscosity product of small-volume ionic liquid samples using quartz crystal impedance analysis

Quartz crystal impedance analysis has been developed as a technique to assess whether room-temperature ionic liquids are Newtonian fluids and as a small-volume method for determining the values of their viscosity-density product, rho eta. Changes in the impedance spectrum of a 5-MHz fundamental frequency quartz crystal induced by a water-miscible room-temperature ionic liquid, 1-butyl-3-methylimiclazolium trifluoromethylsulfonate ([C4mim][OTf]), were measured. From coupled frequency shift and bandwidth changes as the concentration was varied from 0 to 100% ionic liquid, it was determined that this liquid provided a Newtonian response. A second water-immiscible ionic liquid, 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide [C4mim][NTf2], with concentration varied using methanol, was tested and also found to provide a Newtonian response. In both cases, the values of the square root of the viscosity-density product deduced from the small-volume quartz crystal technique were consistent with those measured using a viscometer and density meter. The third harmonic of the crystal was found to provide the closest agreement between the two measurement methods; the pure ionic liquids had the largest difference of approximately 10%. In addition, 18 pure ionic liquids were tested, and for 11 of these, good-quality frequency shift and bandwidth data were obtained; these 12 all had a Newtonian response. The frequency shift of the third harmonic was found to vary linearly with square root of viscosity-density product of the pure ionic liquids up to a value of square root(rho eta) approximately 18 kg m(-2) s(-1/2), but with a slope 10% smaller than that predicted by the Kanazawa and Gordon equation. It is envisaged that the quartz crystal technique could be used in a high-throughput microfluidic system for characterizing ionic liquids.     

H2S photodegradation by TiO2/M-MCM-41 (M = Cr or Ce): Deactivation and by-product generation under UV-A and visible light

M-MCM-41 molecular sieves (M = Ce or Cr) were prepared by a hydrothermal method and impregnated with TiO₂. The materials were characterized by XRD, N₂ adsorption–desorption, DRS and XPS. Their potential application to photooxidize H₂S in a wet gas stream was tested in a continuous flow reactor operating at a flow rate of 110 mL min⁻¹ at 50% relative humidity and using 30 ppm_v of the pollutant. The photocatalytic efficiency using UV-A and visible light was compared to the activity of TiO₂/MCM-41 without heteroatoms incorporated into the MCM-41 structure. It was found that the incorporation of Ce did not improve the performance of TiO₂/MCM-41, but Cr-containing samples presented higher initial efficiency and were able to photooxidize H₂S without formation of SO₂ as a by-product, in contrast to the other prepared samples and to Degussa P-25 TiO₂. Moreover, no other gaseous by-product was detected. The isomorphic incorporation of Cr into the structure of MCM-41 followed by TiO₂ incorporation produced photocatalysts that presented good adsorption capacity and were much more active under visible light than under UV-light. This performance represents an important advantage for solar applications. Their photoactivity depended on the concentration of chromium; the highest efficiency was attained with samples with a Si/Cr ratio of 50. Finally, deactivation was observed as a consequence of sulfate accumulation on the surface of the catalyst and reduction of Cr⁶⁺.     

Design and Guideline Rules for the Performance Improvement of Vertically Integrated Nanogenerator

Piezoelectric nanowires have attracted much scientific interest in the last few years because of their enhanced piezoelectric coefficients at nanometer scale, with promises of efficient mechanical energy harvesters for autonomous integrated systems. This paper presents the design and, for the first time, guideline rules, based on simple analytical expressions, to improve the performance of a mechanical energy harvester integrating vertical ZnO piezoelectric nanowires. Additional simulations were carried out to account more realistically for device geometry. The authors discuss the prospects of such an approach, based on design and material improvement.     

Predictable scheduling of a single machine with breakdowns and sensitive jobs

Production schedules released to the shop floor have two important functions: allocating shop resources to different jobs to optimize some measure of shop performance and serving as a basis for planning external activities such as material procurement, preventive maintenance and delivery of orders to customers. Schedule modification may delay or render infeasible the execution of external activities planned on the basis of the predictive schedule. Thus it is of interest to develop predictive schedules that can absorb disruptions without affecting planned external activities while maintaining high shop performance. We present a predictable scheduling approach, that inserts additional idle time into the schedule to absorb the impacts of breakdowns. The effects of disruptions on planned support activities are measured by the deviations of job completion times in the realized schedule from those in the predictive schedule. We apply our approach to minimizing total tardiness on a single machine with stochastic machine failures. We then extend the procedure to consider the case where job processing times are affected by machine breakdowns, and provide specialized rescheduling heuristics. Extensive computational experiments show that this approach provides high predictability with minor sacrifices in shop performance.     

The effects of ultrasound and light on indocyanine-green-treated tumour cells and tissues

Photodynamic therapy (PDT) is emerging as a treatment modality for the management of neoplastic disease. Despite considerable clinical success, its application for the treatment of deep‐seated lesions is constrained by the inability of visible light to penetrate deeply into tissues. An emerging alternative approach exploits the fact that many photosensitisers respond to ultrasound, eliciting cytotoxic effects on target cells and tissues; this has become known as sonodynamic therapy (SDT). The objectives of this study were 1) to determine whether the IR‐absorbing dye, indocyanine green (ICG), can be employed as a sonosensitiser and 2) to determine whether ultrasound can be used to enhance ICG‐mediated PDT. Exposing ICG‐treated mouse fibrosarcoma cells to ultrasound at an energy density of 30 J cm^?2 decreased cell viability by 65 %. Prior exposure of ICG‐treated cells to light (λ 830 nm) and subsequent treatment with ultrasound led to a 90 % decrease in cell viability. In combination treatments a synergistic effect was observed at lower doses of ultrasound. Microscopic examination of cell populations treated with light or ultrasound demonstrated the production of intracellular reactive oxygen species (ROS). Using a mouse tumour model, treatment with light, ultrasound, or a combination thereof led to respective decreases in tumour growth of 42, 67, and 98 % at day 27 post‐treatment. These results could provide a means of circumventing light‐penetration issues that currently challenge the widespread use of PDT in the treatment of cancer.     

Does stress exacerbate parental differential treatment of siblings? A pattern-analytic approach.

To develop a typology based on family members' perspectives on parental differential treatment of siblings, data from mothers, fathers, firstborn adolescent siblings (M?=?15 years), and second-born adolescent siblings (M?=?12.5 years) from 187 families were submitted to cluster analysis. A 4-cluster solution based on the convergence or divergence of reports and the levels of parental differential treatment was identified and replicated: convergent/all below average (n?=?94), convergent/all above average (n?=?48), divergent/all below average except older sibling (n?=?20), and divergent/all above average except mother (n?=?25). Analyses revealed cluster differences in family structure (e.g., sex of siblings, age spacing) and in parents' perceived levels of stress across several domains (e.g., work, marriage, and individual mental health). (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Molecular Insight into the Therapeutic Effects of Stem Cell-Derived Exosomes in Respiratory Diseases and the Potential for Pulmonary Delivery

Respiratory diseases are the cause of millions of deaths annually around the world. Despite the recent growth of our understanding of underlying mechanisms contributing to the pathogenesis of lung diseases, most therapeutic approaches are still limited to symptomatic treatments and therapies that only delay disease progression. Several clinical and preclinical studies have suggested stem cell (SC) therapy as a promising approach for treating various lung diseases. However, challenges such as the potential tumorigenicity, the low survival rate of the SCs in the recipient body, and difficulties in cell culturing and storage have limited the applicability of SC therapy. SC-derived extracellular vesicles (SC-EVs), particularly SC-derived exosomes (SC-Exos), exhibit most therapeutic properties of stem cells without their potential drawbacks. Similar to SCs, SC-Exos exhibit immunomodulatory, anti-inflammatory, and antifibrotic properties with the potential to be employed in the treatment of various inflammatory and chronic respiratory diseases. Furthermore, recent studies have demonstrated that the microRNA (miRNA) content of SC-Exos may play a crucial role in the therapeutic potential of these exosomes. Several studies have investigated the administration of SC-Exos via the pulmonary route, and techniques for SCs and SC-Exos delivery to the lungs by intratracheal instillation or inhalation have been developed. Here, we review the literature discussing the therapeutic effects of SC-Exos against respiratory diseases and advances in the pulmonary route of delivery of these exosomes to the damaged tissues.