Epitaxial phase‐change materials

Epitaxial $ {\rm Ge}_{2} {\rm Sb}_{2} {\rm Te}_{5} $ thin layers were successfully grown in the metastable cubic phase on both slightly lattice‐mismatched (GaSb) and highly lattice‐mismatched (Si) templates. The higher quality of the films grown on (111)‐oriented substrates is attributed to the tendency to form layered structures in the stable bulk phase as well as to the nature of distortion in the metastable cubic phase. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Rapid Extraction of Volatile Compounds Using a New Simultaneous Microwave Distillation: Solvent Extraction Device

Simultaneous distillation–extraction (SDE) is routinely used by analysts for sample preparation prior to gas chromatography analysis. In this work, a new process design and operation for microwave assisted simultaneous distillation–solvent extraction (MW-SDE) of volatile compounds was developed. Using the proposed method, isolation, extraction and concentration of volatile compounds can be carried out in a single step. To demonstrate its feasibility, MW-SDE was compared with the conventional technique, SDE, for gas chromatography-mass spectrometry (GC-MS) analysis of volatile compounds in a fresh aromatic herb, Zygophyllum album L., a wild salty desert herb belonging to the family Zygophyllaceae. SDE method required a long time (3 h) to isolate the volatile compounds, and large amounts of organic solvent (200 mL of hexane) for further extraction, while MW-SDE needed shorter time (only 30 min) to prepare the sample, and less amount of organic solvent (10 mL of hexane). These results show that MW-SDE–GC-MS is a simple, rapid and solvent-less method for the determination of volatile compounds from aromatic plants.     

Current and efficiency optimization under oscillating forces in entropic barriers

The transport of externally overdriven particles confined in entropic barriers is investigated under various types of oscillating and temporal forces.Temperature,load,and amplitude dependence of the particle current and energy conversion efficiency are investigated in three dimensions.For oscillating forces,the optimized temperature–load,amplitude–temperature,and amplitude–load intervals are determined when fixing the amplitude,load,and temperature,respectively.By using three-dimensional plots rather than two-dimensional ones,it is clearly shown that oscillating forces provide more efficiency compared with a temporal one in specified optimized parameter regions.Furthermore,the dependency of efficiency to the angle between the unbiased driving force and a constant force is investigated and an asymmetric angular dependence is found for all types of forces.Finally,it is shown that oscillating forces with a high amplitude and under a moderate load lead to higher efficiencies than a temporal force at both low and high temperatures for the entire range of contact angle.     

Hydrogenation of cinnamaldehyde in liquid phase in the presence of copper supported catalysts

Copper supported on zirconia is rather selective to cinnamic alcohol. The addition of chromium to such catalysts appreciably increased the activity while preserving a significant cinnamic alcohol selectivity.