Adaptive stochastic approximation algorithm

In this paper, stochastic approximation (SA) algorithm with a new adaptive step size scheme is proposed. New adaptive step size scheme uses a fixed number of previous noisy function values to adjust steps at every iteration. The algorithm is formulated for a general descent direction and almost sure convergence is established. The case when negative gradient is chosen as a search direction is also considered. The algorithm is tested on a set of standard test problems. Numerical results show good performance and verify efficiency of the algorithm compared to some of existing algorithms with adaptive step sizes.     

A convenient procedure for the preparation of Garner’s aldehyde

The palladium/silane reduction of a serine thioester derivative allows for the preparation of enantiomerically pure Garner’s aldehyde from serine, in gram quantities within 24 h.     

Photocatalytic degradation of metoprolol in water suspension of TiO<Subscript>2</Subscript> nanopowders prepared using sol–gel route

Nanocrystalline titanium dioxide (TiO₂) powders have been synthesized by sol–gel method using titanium tetrachloride (TiCl₄) or tetrabutyl titanate (Ti(OC₄H₉)₄ as precursors, different alcohols and calcination temperatures in the range from 400 to 650 °C. The photocatalytic activity of as-prepared powders has been tested for the degradation of metoprolol tartrate salt, a selective β-blocker used to treat a variety of cardiovascular diseases, and compared to photocatalytic activity obtained from Degussa P25. Nanosized TiO₂ powders prepared from TiCl₄ and amyl-alcohol, calcined at 550 °C, displayed an activity comparable to Degussa P25, whereas the sample from the same series, calcined at 650 °C, showed higher photocatalytic activity in the whole range of the catalyst loading. Structural, morphological and surface properties of synthesized TiO₂ nanopowders have been investigated by XRD, SEM, EDS and BET measurements, as well as FTIR and Raman spectroscopy, in order to find out the material properties which enable rapid an efficient decomposition of metoprolol under UV radiation.     

On Mechanics of a High-G Human Centrifuge

This paper presents the kinematic characteristics of a human centrifuge for pilot training. The focus is placed on the influence of the tangential acceleration on human centrifuge performances. The main planetary motion is expressed with an ordinary first-order nonlinear differential equation, which is solved numerically. (© 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

A tractable LIBOR model with default risk

We develop a model for the dynamic evolution of default-free and defaultable interest rates in a LIBOR framework. Utilizing the class of affine processes, this model produces positive LIBOR rates and spreads, while the dynamics are analytically tractable under defaultable forward measures. This leads to explicit formulas for CDS spreads, while semi-analytical formulas are derived for other credit derivatives. Finally, we give an application to counterparty risk.     

Ring closing metathesis/fragmentation route to (Z)-configured medium ring cycloalkenes. Total synthesis of (+/-)-periplanone C

The combination of ring closing metathesis and beta-fragmentation offers an efficient entry into (Z)-configured medium ring cycloalkenes. The fragmentation step can be effected under anionic or radical conditions. The versatility of this method is demonstrated by the total synthesis of (+/-)-periplanone C-a macrocyclic pheromone of Periplaneta americana.     

A short stereoselective synthesis of (+)-aza-galacto-fagomine (AGF)

A catalytic asymmetric synthesis of (+)-aza-galacto-fagomine (AGF) – the most promising compound for the pharmacological chaperone therapy of Krabbe disease – was accomplished in six steps, in 14% overall yield. The synthesis hinges on the combination of organocatalyzed aldolization and reductive hydrazination.     

An aldol approach to the enantioselective synthesis of (-)-oseltamivir phosphate

A formal asymmetric synthesis of the antiviral agent (-)-oseltamivir phosphate is achieved using two aldol reactions as key steps.     

Spectroscopic ellipsometry and polarimetry for materials and systems analysis at the nanometer scale: state-of-the-art, potential, and perspectives

This paper discusses the fundamentals, applications, potential, limitations, and future perspectives of polarized light reflection techniques for the characterization of materials and related systems and devices at the nanoscale. These techniques include spectroscopic ellipsometry, polarimetry, and reflectance anisotropy. We give an overview of the various ellipsometry strategies for the measurement and analysis of nanometric films, metal nanoparticles and nanowires, semiconductor nanocrystals, and submicron periodic structures. We show that ellipsometry is capable of more than the determination of thickness and optical properties, and it can be exploited to gain information about process control, geometry factors, anisotropy, defects, and quantum confinement effects of nanostructures.     

A multiple-curve HJM model of interbank risk

In the aftermath of the 2007?C2009 financial crisis, a variety of spreads have developed between quantities that had been essentially the same until then, notably LIBOR?COIS spreads, LIBOR?COIS swap spreads, and basis swap spreads. By the end of 2011, with the sovereign credit crisis, these spreads were again significant. In this paper we study the valuation of LIBOR interest rate derivatives in a multiple-curve setup, which accounts for the spreads between a risk-free discount curve and LIBOR curves. Towards this end we resort to a defaultable HJM methodology, in which these spreads are explained by an implied default intensity of the LIBOR contributing banks, possibly in conjunction with an additional liquidity factor. Markovian short rate specifications are given in the form of an extended CIR and a Lévy Hull?CWhite model for a risk-free short rate and a LIBOR short spread. The use of Lévy drivers leads to the more parsimonious specification. Numerical values of the FRA spreads and the basis swap spreads computed with the latter largely cover the ranges of values observed even at the peak of the 2007?C2009 crisis.