Ti3+ ion concentration and Ti:sapphire laser performance

The pulsed and CW laser performance of a range of titanium sapphire laser crystals is reported. Titanium ion concentration in the crystals ranged from 0.07 at.% to 0.25 and 0.41 at.% for some recently developed heavily doped crystals. Values of the crystal figure of merit lay between 30 and 220. Threshold, slope efficiency, tunability, and temporal response are assessed. Comparisons are made with the predictions of a simple rate equation model     

Frequency-dependent conductivity in unannealed thin films of As0.40Se0.40Te0.20

Direct current (d.c.) and alternating current (a.c.) conductivity measurements have been performed on unannealed amorphous As_0.40Se_0.40Te_0.20 thin films. The d.c. measurements were performed at temperatures between 143 K and 343 K. The d.c. behaviour of the samples indicates different hopping conduction mechanisms between 143 K-210 K and 210 K-343 K. The a.c. measurements were performed at temperatures between 143 K and 300 K and at frequencies between 110 Hz and 1 MHz. The a.c. conductivity of the films is well represented by the form Cω^s where C and s are found to be temperature dependent parameters. The data are found to fit the correlated barrier hopping model, especially at low temperatures. The comparison of a.c. data with the unified theory of the extended pair approximation shows that the results fit to the quasi universal law predicted by this model, however, qualitative calculations give unreasonable values for the decay parameter α and the exponent l.     

25th Anniversary Article: Interfacing Nanoparticles and Biology: New Strategies for Biomedicine

The exterior surface of nanoparticles (NPs) dictates the behavior of these systems with the outside world. Understanding the interactions of the NP surface functionality with biosystems enables the design and fabrication of effective platforms for therapeutics, diagnostics, and imaging agents. In this review, we highlight the role of chemistry in the engineering of nanomaterials, focusing on the fundamental role played by surface chemistry in controlling the interaction of NPs with proteins and cells.     

Preparation and characterization of κ-carrageenan hydrogel for controlled release of copper and manganese micronutrients

A series of κ-carrageenan (κ-CG) hydrogels were prepared by using glutaraldehyde (GA) as crosslinker for controlled releasing of copper and manganese micronutrients. The hydrogels were characterized by gel content, swelling and degradation tests, Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy (ATR-FTIR) and Scanning Electron Microscope (SEM) observations. The variations of swelling percentages (S%) with time, temperature and pH were determined for all hydrogels. As the amounts of crosslinker increased, S% decreased regularly in contrast to gel content results. The higher swelling values were obtained in basic medium than acidic and neutral mediums for all κ-CG hydrogels. Releasing of copper and manganese micronutrients from κ-CG hydrogels was investigated in water and soil. A simulated releasing model was also applied to estimate the releasing behaviors in agricultural irrigations. In all release studies, the cumulative release values increased with decreasing GA amounts. The release kinetic parameters were also calculated. It was detected that the releasing of micronutrients in soil was slower than that in water.     

Solubilization of Hydrophobic Catalysts Using Nanoparticle Hosts

A modular strategy for the solubilization and protection of hydrophobic transition metal catalysts using the hydrophobic pockets of water soluble gold nanoparticles is reported. Besides preserving original catalyst activity, this encapsulation strategy provides a protective environment for the hydrophobic catalyst and brings reusability. This system provides a versatile platform for the encapsulation of different hydrophobic transition metal catalysts, allowing a wide range of catalysis in water while uniting the advantages of homogeneous and heterogeneous catalysis in the same system.     

An intelligent multimedia information system for multimodal content extraction and querying

Multimedia Tools and Applications - This paper introduces an intelligent multimedia information system, which exploits machine learning and database technologies. The system extracts semantic...     

Effect of processing techniques on antioxidative enzyme activities, antioxidant capacity, phenolic compounds, and fatty acids of table olives

In this study, olive fruits (Olea europeae cv. Gemlik) of the most common sources of table olives in Turkey were used. Total polyphenol content (TPC), antioxidant capacity (AC), and antioxidant enzymes (catalase, CAT; ascorbate peroxidase, APX; and glutathione reductase, GR) of table olives were compared by 4 different methods of ripe table olive processing. Results revealed that TPC of the processed olives ranged from 117.44 to 418.69 mg gallic acid equivalents/g fresh weight (f.w.). The highest AC as mg Trolox equivalents of 189.58/g f.w. was obtained from unprocessed black olives. CAT, APX, and GR activities of unprocessed olives were higher than those obtained in all processed olives. In conclusion, TPC, AC, and antioxidant enzyme activities are strongly affected by fruit ripening and processing in table olives of ‘Gemlik’ cultivar. In addition, the best processing technique is untreated black olives in brine for antioxidant properties.