Thermal rectification in three-dimensional asymmetric nanostructure

Previously, thermal rectification has been reported in several low-dimensional shape-asymmetric nanomaterials. In this Letter, we demonstrate that a three-dimensional crystalline material with an asymmetric shape also displays as strong thermal rectification as low-dimensional materials do. The observed rectification is attributed to the stronger temperature dependence of vibration density of states in the narrower region of the asymmetric material, resulting from the small number of atomic degrees of freedom directly interacting with the thermostat. We also demonstrate that the often reported "device shape asymmetry" is not a sufficient condition for thermal rectification. Specifically, the size asymmetry in boundary thermal contacts is equally important toward determining the magnitude of thermal rectification. When the boundary thermal contacts retain the same size asymmetry as the nanomaterial, the overall system displays notable thermal rectification, in accordance with existing literature. However, when the wider region of the asymmetric nanomaterial is partially thermostatted by a smaller sized contact, thermal rectification decreases dramatically and even changes direction.     

MR fingerprinting of the prostate

Magnetic Resonance Materials in Physics, Biology and Medicine - Multiparametric magnetic resonance imaging (mpMRI) has been adopted as the key tool for detection, localization, characterization,...     

Effect of sprouting on physicochemical,antioxidant and flavonoid profile of onion varieties

This study investigated the impact of sprouting in four Indian onion varieties (Punjab White, Punjab Naroya, PRO‐6 and Commercial). Results showed significant (P < 0.05) increase in protein, crude fibre, ascorbic acid content, total phenol content, total flavonoid content, antioxidant activity, anthocyanin content and significant (P < 0.05) decrease in total carbohydrate, energy value and hardness due to sprouting in all the four varieties. HPLC analysis revealed irregular pattern of increase and decrease in flavonoid components. There was no particular trend observed within analysed flavonols due to sprouting in all the four varieties except with the maximum increase in quercetin (219.3–287.4 mg kg^?1), kaempferol (13.8–17 mg kg^?1), myricetin (34.6–40.9 mg kg^?1), quercetin‐3?‐glucoside (2.9–4.1 mg kg^?1) and quercetin‐4?‐glucoside (83–87.1 mg kg^?1) in case of PRO‐6 variety only. The present research work implied sprouting to be beneficial in onion as nutritional and functional potential of all the four onion varieties was improved by sprouting.     

Wet chemical synthesis of ZnO nanocrystals: dependence of growth and morphology on the solvent composition

Zinc oxide (ZnO) nanocrystals were prepared using a wet chemical route starting from zinc acetate dihydrate dissolved in pure ethanol, pure water, and mixtures of ethanol and water. X-ray diffraction (XRD) studies along with thermogravimetric analyses results show that ZnO begins to crystallize at a temperature lower than 100 °C in a starting solution having 1:4 ethanol–water volume ratio. For other starting solutions, ZnO forms above 150 °C. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) studies confirm the formation of nanoparticles of size ~15–20 nm and XRD analysis shows that the particles crystallize in the wurtzite structure. SEM and TEM studies show that ZnO particles grown in pure ethanol, pure water and in ethanol–water mixtures (other than the 1:4 mixture) have similar morphology, with the nanocrystals forming randomly grouped clusters. In the case of 1:4 solvent, however, the morphology is different, ZnO in this case growing in the form of chain like structures which appear like rods. Room temperature photoluminescence spectra exhibit a strong emission band in the red region probably caused by transitions between deep levels involving zinc interstitials.     

Magnetically Separable Copper Ferrite Nanoparticles‐Catalyzed Synthesis of Diaryl,Alkyl/Aryl Sulfones from Arylsulfinic Acid Salts and Organohalides/Boronic Acids

A recyclable, inexpensive, non‐toxic and environmentally benign catalytic system comprised of magnetically separable copper ferrite (CuFe₂O₄) nanoparticles has been developed for the synthesis of diaryl, alkyl/aryl sulfones. Arylsulfinic acid salts are coupled with various alkyl/aryl halides/boronic acids to afford the corresponding diaryl, alkyl/aryl sulfones in good to excellent yields under the identical catalytic system. A wide range of functional group tolerance, with facile recovery of the catalyst by application of an external magnetic field, and consistently high catalytic efficiency for five consecutive cycles render the protocol operationally attractive.