Thermolysis of symmetrical dithiobiurea and thioureidoethylthiourea derivatives

Microwave and thermal heterocyclization of N,N′‐disubstituted hydrazinecarbothioamide 1a,b and substituted thioureidoethylthioureas 2a–c as well as 1‐phenyl‐3[2‐(3‐phenylthio‐ureido)phenyl]thiourea 6 are reported. © 2003 Wiley Periodicals, Inc. Heteroatom Chem 14:535–541, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.10188     

Magnetic Nanoparticle Thermometry via Controlled Diffusion

The process of magnetic nanoparticle heating releases enormous amounts of thermal energy. Through typical calorimetric analyses, the total thermal energy released can be easily quantified; however, knowledge of nanoscale temperature is necessary. Herein, a novel method of nanoscale thermometry by analyzing intra-particle diffusion in core–shell nanoparticles is proposed. Heating the iron cores with an alternating magnetic field in a saline suspension encourages the diffusion of sodium ions into the silica shells of the particles, which is modeled numerically; however, experimental measurements are needed in order to provide accurate diffusivity estimations. After determining the diffusion characteristics from X-ray photoelectron spectroscopy) depth profiling of silica films, energy dispersive analysis with high-resolution transmission electron microscopy measures the sodium ion gradient within single particles before and after heating. When compared directly to the numerical simulations, the results indicate that the temperature gradient between particles and saline suspension reaches significantly higher temperatures than the macro-scale temperature of the solution. By accurately knowing the thermal gradient between nanoparticles and the surrounding medium, nanoparticles can be engineered to limit surface resistances as much as possible and promote high rates of thermal energy transfer.     

Phenylbiguanide as electron donor in heterocyclic synthesis

Phenylbiguanide reacts with some π-acceptors such as TCNE, TCNQ, CNIND, DCNQ, and CHL-o, if any. opy; 2003 Wiley Periodicals, Inc. Heteroatom Chem 15:63–66, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.10213     

An inverse spectral problem for a fractional Schrödinger operator

Archiv der Mathematik - We establish that the potential appearing in a fractional Schrödinger operator is uniquely determined by an internal spectral data.