EPR study of aerosols with carbonaceous products in the urban air

The method of EPR spectroscopy is applied for the first time in the systematic quantitative estimations of carbonaceous solids present as aerosols in the urban air. The quantitative data obtained are in concert with the estimations using other conventional methods. The advantage of the EPR method in such estimations is that it is not destructive, exhibit selectivity only to paramagnetic species which are in fact the pyrolyzed products and not to other polycyclic aromatic hydrocarbons, the analyses are simple, time saving and inexpensive.     

Synthesis of linear systems with desired equivalent form

A method for feedback synthesis of linear control systems with desired linearly equivalent form of the closed loop system matrix is proposed. The method is based on the serial canonical form of linear multivariable systems which is an alternative to the Luenberger canonical form. A stable computational algorithm for finding the serial canonical form using orthogonal similarity transformations is described. The algorithm for synthesis involves a simple recurrent procedure and gives the possibility to achieve any attainable equivalent form of the closed loop system. The results obtained are extended to the synthesis of reduced order state observers.     

On the Cu2 bands in the cold cathode discharge in inert gas

The Cu₂ AX and BX bands were obtained in a cylindrical copper cold cathode neon and argon discharges (ref.I) at gas pressure I0–I5 torr and current densities 200 – 300 mA.cm^?2. torr^?2. The result may be of importance for the cathode sputter laser developments and the spectral analysis.     

Chemical composition of propolis from Canada, its antiradical activity and plant origin

The chemical composition of propolis from two regions in Canada was studied: Boreal forest and the Pacific coastal forest that lie outside the area of distribution of Aigeiros poplars, the usual propolis source plants. In the sample from Victoria, p-hydroxyacetophenone, benzyl hydroxybenzoate and cinnamic acid were the major components, accompanied by significant amounts of dihydrochalcones, which allowed the identification of its plant source: Populus trichocarpa of section Tacamahaca. Three dihydrochalcones were new for propolis. The sample from Richmond was characterized by large amounts of p-coumaric and cinnamic acid, typical for poplars of section Leuce, subsection Trepidae, its plant source was identified as P. tremuloides. Both samples showed a good radical scavenging activity against DPPH. Obviously, the Northern type propolis is a promising potential source of biologically active substances and deserves further investigation.     

Open-circuit reduction of oxygen coverage on Pt by organic substances: IV. Experimental verification of the dependences derived

The equations derived in the previous three parts are experimentally verified using propionaldehyde as a model compound. The kinetic parameters of the process are found. As the consistency of the experimental results with the predicted relationships is quite good it seems to be justified to conclude that the overall process of the open-circuit reduction of the oxygen coverage on Pt by organic substances follows the reaction mechanism suggested and is well described by the general kinetic equations derived.     

Quantum dynamics at finite temperature: Time-dependent quantum Monte Carlo study

In this work we investigate the ground state and the dissipative quantum dynamics of interacting charged particles in an external potential at finite temperature. The recently devised time-dependent quantum Monte Carlo (TDQMC) method allows a self-consistent treatment of the system of particles together with bath oscillators first for imaginary-time propagation of Schrödinger type of equations where both the system and the bath converge to their finite temperature ground state, and next for real time calculation where the dissipative dynamics is demonstrated. In that context the application of TDQMC appears as promising alternative to the path-integral related techniques where the real time propagation can be a challenge.     

A convergent,scalable and stereoselective synthesis of azole CYP51 inhibitors

The study and development of azole-based CYP51 inhibitors is an active area of research across disciplines of biochemistry, pharmacology and infectious disease. Support of in vitro and in vivo studies require the development of robust asymmetric routes to single enantiomer products of this class of compounds. Herein, we describe a scalable and enantioselective synthesis to VNI and VFV, the two potent inhibitors of protozoan sterol 14α-demethylase (CYP51) that are currently under consideration for clinical trials for Chagas disease. A key transformation is the Jacobsen Hydrolytic Kinetic Resolution (HKR) reaction. The utility of the synthetic route is illustrated by the preparation of >25 g quantities of single enantiomers of VNI and VFV.     

Reactions of Podophyllotoxin with DDQ

Introduction 2, 3-Dichloro-5, 6-dicyanobenzoquinone (DDQ) can react with lignans of the mono- arylidene-butyrolactone1, aryltetralin2, dibenzylbutane3 and aryltetralin-butyrolactone4,5 series. We have studied the reactions of this reagent with podophyllotoxin 1, which is a well-known natural product on account of its long history of use in folk medicine and the biological activity of its many derivatives6. In particular, derivatives of 4-demethyl epipodophyllotoxin are used in cancer chemo…     

Attosecond time-scale intra-atomic phase matching of high harmonic generation.

Using a model of high-harmonic generation that couples a fully quantum calculation with a semiclassical electron trajectory picture, we show that a new type of phase matching is possible when an atom is driven by an optimal optical waveform. For an optimized laser pulse shape, strong constructive interference is obtained in the frequency domain between emissions from different electron trajectories, thereby selectively enhancing a particular harmonic order. This work demonstrates that coherent control in the strong-field regime is possible by adjusting the peaks of a laser field on an attosecond time scale.