Indium(III) bromide catalyzed one-pot synthesis of trichloromethylated tetrahydropyrimidinones

One-pot condensation of ethyl trichloroacetoacetate 1 with p-substituted aromatic aldehydes (Ph, 4-Me-C₆H₄, 4-Cl-C₆H₄, 4-MeO-C₆H₄) or furfural, and urea or thiourea catalyzed by indium(III) bromide affords eight trichloromethylated tetrahydropyrimidinones, in high yields.     

Influence of lasers propagation delay on the sensitivity of atom interferometers

In atom interferometers based on two photon transitions, the delay induced by the difference of the laser beams paths makes the interferometer sensitive to the fluctuations of the frequency of the lasers. We first study, in the general case, how the laser frequency noise affects the performance of the interferometer measurement. Our calculations are compared with the measurements performed on our cold atom gravimeter based on stimulated Raman transitions. We finally extend this study to the case of cold atom gradiometers.     

Analysis of FSS with Dielectric Losses at Millimeter Wave Band Using the Transverse Transmission Line Method

The analysis of periodic structures on isotropic substrates with dielectric losses is presented. Frequency selective surface structures composed by an array of conducting patch elements are considered. This analysis uses the Galerkin method in combination with the transverse transmission line method, in the Fourier domain, to determine the reflection and transmission characteristics of the considered structures. The analysis provides very accurate results compared to those presented by other authors.     

Multi-time-scale synchronization and information processing in bursting neuron networks

We analyze the effect of synchronization in networks of chemically coupled multi-time-scale (spiking-bursting) neurons on the process of information transmission within the network. Although, synchronization occurs first in the slow time-scale (burst) and then in the fast time-scale (spike), we show that information can be transmitted with low probability of errors in both time scales when the bursts become synchronized. Furthermore, we show that for networks of non-identical multi-time-scales neurons, complete synchronization is no longer possible, but instead burst phase synchronization. Our analysis shows that clusters of burst phase synchronized neurons are very likely to appear in a network for parameters far smaller than the ones for which the onset of burst phase synchronization in the whole network takes place.     

Micron-Sized Imaging System Based on Multimode Waveguides

The design and analysis of an extremely compact micron-sized imaging system consisting of a multimode rectangular waveguide is presented, and both the on- and off-axis imaging characteristics in the far field are studied. The imaging capabilities of this system are comparable to that of a high numerical aperture lens system with the advantage that it is extremely compact, simple to be fabricated and can be extended to arrays.     

Infrared and far-infrared spectroscopy of CH3OH: TeraHertz laser lines and assignments

We use a ¹³CO₂ laser as optical pumping source to search for new THz laser lines generated from ¹³CH₃OH. Nineteen new THz laser lines (also identified as far-infrared, FIR) ranging from 42.3 μm (7.1 THz) to 717.7 μm (0.42 THz) are reported. They are characterized in wavelength, offset, relative polarization, relative intensity, and optimum working pressure. We have assigned eight laser lines to specific rotational energy levels in the excited state associated with the C-O stretching mode.     

On-axis calcium magneto-optical trap loaded with a focused decelerating laser

We report on a simple scheme to efficiently load an on-axis magneto-optical trap (MOT) from a decelerated atomic beam, which avoids perturbation by radiation pressure from the decelerating laser. This has been tightly focused near the MOT center, with a waist size much smaller than the atomic cloud. For comparison, and in order to test the efficiency of this non-optimum deceleration geometry we have employed a second, independent decelerating laser, with a profile mode matched to the atomic beam. Using a Calcium MOT, good performance has been achieved and for an oven temperature of 580 °C we loaded 1.2(2)×10⁷ atoms in 16(1)ms. The technique described here has been essential for the sensitive detection of cold collisions, which represent minor losses in MOTs of alkaline-earth metal elements (R.L. Cavasso-Filho, A. Scalabrin, D. Pereira, F.C. Cruz: Phys. Rev. A, 67, 021402(R) (2003)). PACS 32.80.Pj, 39.25.+k, 39.10.+j     

LETTER: Some Remarks on the Neutrino Oscillation Phase in a Gravitational Field

The weak gravitational field expansion method to account for the gravitationally induced neutrino oscillation effect is critically examined, then it is shown that the splitting of the neutrino phase into a "kinematic" and a "gravitational" phase is not always possible because the relativistic factor modifies the particle interference phase splitting condition in a gravitational field.     

Determination of anthraquinones in Rhamnus purshiana using high-performance liquid chromatography coupled to diode array detector and simple ultraviolet spectroscopic analysis

A new method based on Ultraviolet spectrophotometry was developed and compared with that based on high-performance liquid chromatography for the determination and quantification of anthraquinones in the extracts of Rhamnus purshiana bark. A validated quantitative analysis of cascaroside A, cascaroside B, emodin, and aloe-emodin in these herbal products has been previously performed using high-performance liquid chromatography coupled with a diode array detector. In the high-performance liquid chromatography analysis, all the anthraquinones showed satisfactory regression (r² > 0.98) within the test ranges, and the recovery was in the range of 94–117%. The limits of detection and quantification were 0.008–0.010 and 0.029–0.035 μg/mL, respectively. Hierarchical cluster analysis and principal component analysis showed differences in the anthraquinones determined from herbal samples. Subsequently, a simple and low-cost ultraviolet spectrophotometric methodology for the quantitative analysis of the same compounds in the extracts was applied, and all the contents were determined. A paired t-test confirmed that there were no significant differences between the two methods. Our results revealed that the developed method is simple and provides the ability to discriminate and control the quality of anthraquinones in herbal products.     

Physicochemical characterization of a new raw material obtained from leaves of <Emphasis Type="Italic">Syzygium cumini</Emphasis> (L.) Skeel (Myrtaceae)

The aim of this study was to determine the physicochemical characteristics of leaves of Syzygium cumini L. Skeels plant and characterize the extract of this plant by analytical techniques. Pharmacopeial methods of physicochemical analysis were used, including morphological characterization of the particle, thermal analysis, infrared spectroscopy and X-ray diffraction. The plant drug was presented as a coarse powder, within the appropriate Brazilian Pharmacopoeia parameters. The X-ray diffraction, optical microscopy and scanning electron microscopy suggested that the extract particles are amorphous and have irregular shapes, so that clusters of different sizes and morphologies are displayed. Thermal decomposition of the organic components in the sample started in a step that occurred between 151.64 and 209.27 °C with mass loss of 9.08 %, followed by another step with more significant mass loss (28.16 %). The infrared spectrum, in turn, showed many functional groups of compounds present in the lyophilized extract in different absorption bands. The results showed that the analytical techniques allowed us to characterize the physicochemical properties of the plant leaves, which may be useful in the production of new herbal medicines.