Selective photo-deposition of Cu onto the surface of monodisperse oleic acid capped TiO2 nanorods probed by FT-IR CO-adsorption studies

A novel, non-aqueous, organometallic route to nanocomposite Cu@TiO2 materials is presented. TiO2 nanorods stabilized with oleic acid (OLA) were used as support for the photo-assisted deposition of Cu using the organometallic Cu(II) precursor [Cu(OCH(CH3)CH2N(CH3)2)2] (1). The copper precursor penetrates through the shell of OLA and is photo reduced to deposit Cu0 directly at the surface of the TiO2 rods. The obtained Cu decorated nanorods were still soluble in nonpolar organic solvents without change of the morphology of nanorods. The Cu@TiO2 colloid was characterized by means of UV-VIS, XRD, AAS, and HRTEM. FTIR CO adsorption studies provide evidence for Cu0 anchored at the titania surface by a characteristic absorption at 2084 cm-1. Comparative studies of Cu-deposition were performed using CuCl2 as simple Cu source which proved that the concept of organometallic disguise of the metal centre results in a higher reaction rate and the circumvention of non-selective reduction, parasitic side reactions and undesired agglomeration of the OLA stabilized titania nanorods.     

A versatile approach to the regioselective synthesis of diverse (−)-epicatechin-β-d-glucuronides

A versatile new approach is reported for the total synthesis of five glucuronide metabolites of epicatechin, using selective protection/deprotection techniques.     

SQUID-based measuring systems

A program has been developed and initiated at the Indira Gandhi Centre for Atomic Research (IGCAR) for the utilization of SQUID sensors in various application areas. DC SQUID sensors based on Nb-AlO _x -Nb Josephson junctions have been designed and developed inhouse along with associated flux-locked loop (FLL) electronics. A compact low field SQUID magnetometer insertible in a liquid helium storage dewar has also been developed inhouse and is in use. Efforts to build a high field SQUID magnetometer, SQUID-DAC system, are in progress. A planar gradiometric DC SQUID sensor for non-destructive evaluation (NDE) application to be used in relatively unshielded environment has been designed and developed. An easily portable NDE cryostat with a small lift-off distance, to be used in external locations has been designed and tested. The magnetic field produced by a given two-dimensional current density distribution is inverted using the Fourier transform technique.     

Optical filters with panchromatic emulsion layers for image processing

Amplitude filters with non-linear adaptive performance in the Fourier plane of a mirror optical system are considered. Panchromatic silver bromide layers with a printout effect are employed. The processing of binary and grey-scale images with the aid of a passively adaptive mirror filtering block is investigated.     

The use of acoustical test fixtures for the measurement of hearing protector attenuation. Part II: Modeling the external ear, simulating bone conduction, and comparing test fixture and real-ear data

This paper investigates two main features of the human head which influence the measured attenuation of circumaural and intraaural hearing protection devices (HPDs): the external ear and the different pathways of bone conduction. A theoretical model for the external ear shows that its influence on the insertion loss of HPDs, on the sensitivity level of headphones or earphones, and on the insertion gain of hearing aids, all can be described by one equation. While it is not necessary to simulate the eardrum impedance in order to measure the insertion loss of earmuffs and the sensitivity level of headphones with acoustical test fixtures (ATFs), the required accuracy of an ear simulator is more stringent when the same measurements are performed on intraaural devices. For the evaluation of HPDs, bone conduction plays an important role. We have developed a model to estimate HPD-dependent bone conduction effects. The model includes two bone conduction sources: one in the external ear and one in the middle ear. The model explains, for example, the occlusion effect of HPDs and the masking error at low frequencies due to physiological noise that arises when real-ear attenuation at threshold (REAT) measurements are made. Consequently, objectively measured insertion loss can now be used to predict REAT with improved accuracy. ATF and REAT data are compared using nine earmuffs and nine earplugs. In the majority of cases, the two sets of data agree well. Discrepancies are discussed.     

Das Clebsch'sche Sechseck

Ohne Zusammenfassung     

Ueber cyklisch-projective Punktquadrupel in zwei collinearen Räumen

Ohne Zusammenfassung     

Damage formation in Ge during Ar and He implantation at 15 K

Ar⁺ and He⁺ ions were implanted into Ge samples with (1 0 0), (1 1 0), (1 1 1) and (1 1 2) orientations at 15 K with fluences ranging from 1×10¹¹ to 1×10¹⁴ cm⁻² for the Ar⁺ ions and fluences ranging from 1×10¹² to 6×10¹⁵ cm⁻² for the He⁺ ions. The Rutherford backscattering (RBS) technique in the channelling orientation was used to study the damage built-up in situ. Implantation and RBS measurements were performed without changing the target temperature. The samples were mounted on a four axis goniometer cooled by a close cycle He cryostat. The implantations were performed with the surface being tilt 7° off the ion beam direction to prevent channelling effects. After each 300 keV Ar⁺ and 40 keV He⁺ implantation, RBS analysis was performed with 1.4 MeV He⁺ ions.For both the implantation ions, there is about no difference between the values found for the damage efficiency per ion for the four different orientations. This together with the high value (around 5 times higher than that found in Si), gives rise to the assumption of amorphous pocket formation per incident ion, i.e. direct impact amorphization, already at low implantation fluences. At higher fluences, when collision cascades overlap, there is a growth of the already amorphized regions.     

Applicability domains for classification problems: Benchmarking of distance to models for Ames mutagenicity set

The estimation of accuracy and applicability of QSAR and QSPR models for biological and physicochemical properties represents a critical problem. The developed parameter of "distance to model" (DM) is defined as a metric of similarity between the training and test set compounds that have been subjected to QSAR/QSPR modeling. In our previous work, we demonstrated the utility and optimal performance of DM metrics that have been based on the standard deviation within an ensemble of QSAR models. The current study applies such analysis to 30 QSAR models for the Ames mutagenicity data set that were previously reported within the 2009 QSAR challenge. We demonstrate that the DMs based on an ensemble (consensus) model provide systematically better performance than other DMs. The presented approach identifies 30-60% of compounds having an accuracy of prediction similar to the interlaboratory accuracy of the Ames test, which is estimated to be 90%. Thus, the in silico predictions can be used to halve the cost of experimental measurements by providing a similar prediction accuracy. The developed model has been made publicly available at http://ochem.eu/models/1 .