Exploiting Electrostatics To Generate Unsaturation: Oxidative GeE Bond Formation Using a Non π‐Donor Stabilized [R(L)Ge:]+ Cation

The two‐coordinate germanium cation [(IDipp){(Me₃Si)₂CH}Ge:]⁺ has been synthesized, which lacks π‐donor stabilization of the metal center and consequently has a very small HOMO–LUMO gap (187 kJ mol^?1). It undergoes a variety of facile oxidative bond‐forming reactions, most notably allowing access to the first examples of Group 14 metal cations containing M?E multiple bonds (E=C, N). The use of an electrostatic (rather than purely steric) strategy to discourage aggregation means that less bulky systems (for example, containing a primary alkylidene fragment, ?CHR) are accessible.     

Nanostructured Lipid Carriers (NLC)-Based Gel Formulations as Etodolac Delivery: From Gel Preparation to Permeation Study

Topical administration of drug is an attractive alternative to the oral administration as it provides a reduction in adverse reactions and an enhancement of therapeutic effects. The use of lipid carriers in hydrogel structures makes it possible to introduce lipophilic substances in a dissolved form. In this study, an NSAID from the BCS class II, etodolac (ETD), was used. The nanostructured lipid carriers (NLC) obtained with ETD were incorporated into semi-solid forms (gels). Hydrogels with the suspended drug and oleogel were also prepared for comparison purposes. The obtained gels were tested in terms of pH, viscosity, rheological, mechanical, and bioadhesive properties. The release and permeation through membranes were also studied. All tested formulations were characterized by a pH below 7, which ensured the physiological state of the skin. The viscosities of all gels decreased with increasing shear rate, indicating non-Newtonian behavior. The fastest ETD release was observed for NLC with a Carbopol base (formulation F1); a similar result was noticed in the permeation test. The developed gel formulations containing ETD-NLC dispersion and Carbopol or Poloxamer as gelling agents were stable and possessed beneficial pharmaceutical properties.     

Photoinduced Electron Transfer between CdS and CdTe Nanoparticles in Colloidal Solutions

The photochemical behavior of solutions containing a mixture of CdS and CdTe nanoparticles under pulsed irradiation conditions was investigated. It was shown that electron transfer from the CdS particles to the CdTe nanoparticles occurs during the photoexcitation of such systems. The effectiveness of the process is increased with increase in the size of the CdTe nanoparticles. Such behavior is due to decrease in the potential of the CdTe conduction band with increase in the size of the nanoparticles as a result of the appearance of quantum-dimensional effects.     

Simultaneous Determination of Cadmium,Lead, Copper and Mercury Ions Using Organofunctionalized SBA‐15 Nanostructured Silica Modified Graphite–Polyurethane Composite Electrode

A new sensor has been developed for the simultaneous detection of cadmium, lead, copper and mercury, using differential pulse and square wave anodic stripping voltammetry (DPASV and SWASV) at a graphite–polyurethane composite electrode with SBA‐15 silica organofunctionalized with 2‐benzothiazolethiol as bulk modifier. The heavy metal ions were preconcentrated on the surface of the modified electrode at ?1.1 V vs. SCE where they complex with 2‐benzothiazolethiol and are reduced to the metals, and are then reoxidized. Optimum SWASV conditions lead to nanomolar detection limits and simultaneous determination of Cd²⁺, Pb²⁺, Cu²⁺ and Hg²⁺ in natural waters was achieved.     

Tin oxide coating on polytetrafluoroethylene films in aqueous solutions

Polytetrafluoroethylene (PTFE) films were successfully coated with tin oxide in aqueous solutions. Tin oxide was crystallized in the solution and formed nanocrystal coatings on the polymer films. The coatings consisted of SnO₂ and SnO crystals. They were assemblies of tin oxide nanosheet of about 10 to 50 nm in size and about 5 nm in thickness. The nanocrystal films can be exfoliated from the PTFE substrates. Tin oxide nanocrystal films had a rough liquid surface and a dense substrate‐side surface. Transparency of PTFE films coated with tin oxide was same as that of bare PTFE films in the range from 400 to 800 nm. The PTFE films coated with tin oxide nanocrystals can be pasted on desired substrates. Copyright © 2009 John Wiley & Sons, Ltd.