Selective enzymatic reduction of aldehydes

Highly selective enzymatic reductions of aldehydes to the corresponding alcohols was performed using an E. coli JM109 whole cell biocatalyst. A selective enzymatic method for the reduction of aldehydes could provide an eco-compatible alternative to chemical methods. The simplicity, fairly wide scope and the very high observed chemoselectivity of this approach are its most unique features.     

Microstructure and magnetic properties of Fe72.5Cu1M2V2Si13.5B9 (M=Nb, Mo, (NbMo), (MoW)) nanocrystalline alloys

The microstructure and magnetic properties of Finemet-type Fe_72.5Cu₁M₂V₂Si_13.5B₉ (M=Nb, Mo, (NbMo), (MoW)) alloys have been systematically studied. Results show that the nanocrystalline alloy with M=NbMo has the smallest grain size of about 8 nm. The order of the effect of Nb, Mo and W additions in decreasing the α-Fe grain size in nanocrystalline alloys is Nb>Mo>W. The best DC soft magnetic properties are obtained in the alloy with M=Nb. In the case of AC soft magnetic properties, the Nb alloy also exhibits a very low core loss comparing with typical Finemet alloy. Therefore, the Nb alloy is suitable for use as a transformer core material. In addition, it is shown that a narrow grain size distribution and a uniform dispersion of α-Fe grains in the amorphous matrix are very crucial for the development of new Finemet-type nanocrystalline alloys with good soft magnetic properties.     

Raster microdiffraction with synchrotron radiation of hydrated biopolymers with nanometre step-resolution: case study of starch granules

X-ray radiation damage propagation is explored for hydrated starch granules in order to reduce the step resolution in raster-microdiffraction experiments to the nanometre range. Radiation damage was induced by synchrotron radiation microbeams of 5, 1 and 0.3?μm size with ～0.1?nm wavelength in B-type potato, Canna edulis and Phajus grandifolius starch granules. A total loss of crystallinity of granules immersed in water was found at a dose of ～1.3?photons?nm(-3). The temperature dependence of radiation damage suggests that primary radiation damage prevails up to about 120?K while secondary radiation damage becomes effective at higher temperatures. Primary radiation damage remains confined to the beam track at 100?K. Propagation of radiation damage beyond the beam track at room temperature is assumed to be due to reactive species generated principally by water radiolysis induced by photoelectrons. By careful dose selection during data collection, raster scans with 500?nm step-resolution could be performed for granules immersed in water.     

A comparative study of DRL-lift and lift on integrated polyisobutylene polymer matrices

This paper presents a comparative study of polymer pixel on sensors obtained by Laser Induced Forward Transfer (LIFT) assisted by a triazene polymer as Dynamic Release Layer (DRL). Polyisobutylene (PIB) was selected as model for chemoselective polymers which could be used as hydrogen-bond acidic polymer for vapor sensors.     

Polymer pixel enhancement by laser-induced forward transfer for sensor applications

This paper presents polymer pixel printing for applications in chemoselective sensors where nanosecond laser direct transfer methods, with a triazene polymer (TP) acting as a Dynamic Release Layer (DRL), are used. A systematic study of laser fluence, donor film morphology and both single- and multiple-pixel deposition were optimized with the final goal to obtain continuous pixels of sensitive polymers, polyethylenimine (PEI) and polyisobutylene (PIB), on SAW surfaces. Morphology characterization after the laser transfer has been performed by Optical Microscopy and Scanning Electron Microscopy (SEM). The responses of the coated transducers were measured after deposition with different laser fluences and it was found that a fluence under 625 mJ/cm² was required in order to prevent damage of the interdigital transducers (IDT) of the sensor devices. The sensitivity of the polymer coated devices to acetone concentrations gives an indication that LIFT can be used for printing sensitive polymer pixels onto transducer devices.     

A ketogenic diet increases succinic dehydrogenase (SDH) activity and recovers age-related decrease in numeric density of SDH-positive mitochondria in cerebellar Purkinje cells of late-adult rats

Ketogenic diets (KDs) have been applied in the therapy of paediatric epilepsy for nearly a century. Recently, beneficial results have also been reported on metabolic disorders and neurodegeneration, designating aged individuals as possible recipients. However, KDs efficacy decrease after the suckling period, and very little is known about their impact on the aging brain. In the present study, the effect on the neuronal energetic supply of a KD containing 20% of medium chain triglycerides (MCT) was investigated in Purkinje cells of the cerebellar vermis of late-adult (19-month-old) rats. The animals were fed with the KD for 8 weeks, and succinic dehydrogenase (SDH) activity was cytochemically determined. The following parameters of SDH-positive mitochondria were evaluated by the use of a computer-assisted image analysis system connected to a transmission electron microscope: numeric density (Nv), average volume (V), volume density (Vv), and cytochemical precipitate area/mitochondrial area (R). Young, age-matched, and old animals fed with a standard chow were used as controls. We found significantly higher Nv in MCT-KD-fed rats vs. all the control groups, in young vs. late-adult and old controls, and in late-adult vs. old controls. V and Vv showed no significant differences among the groups. R was significantly higher in MCT-KD-fed rats vs. all the control animals, and in old vs. young and late-adult controls. Present data indicate that the ketogenic treatment counteracted age-related decrease in numeric density of SDH-positive mitochondria, and enhanced their metabolic efficiency. Given the central role of mitochondrial impairment in age-related physio-pathological changes of the brain, these findings may represent a starting point to examine novel potentialities for KDs.     

Ti(SO_4)_2水解-水热法制备锐钛型纳米TiO_2及其光催化性能

以Ti(SO4)2水溶液为原料,在水热条件下直接水解合成了锐钛型纳米TiO2颗粒。利用透射电镜(TEM)、X射线衍射(XRD)、BET低温吸附和紫外-可见光谱(UV-Vis)等方法对产物进行了表征,并研究了样品光催化降解甲基橙(MO)的性能。结果表明所制得纳米TiO2颗粒为锐钛矿型,晶型良好,平均粒径为24 nm,BET比表面积约为56.20 m2.g-1。光催化活性与商品纳米TiO2(P25)相近,具有良好的工业应用前景。