Phytochemical screening and biological activities of the oil components of Prunus domestica Linn

Phytochemical screening of three different oil fractions, obtained from n-hexane extract of Prunus domestica shoots were analyzed by GC and GC–MS. It resulted in the identification of 9, 16 and 24 compounds which representing 92.56%, 90.6% and 90.69% of these oil fractions, respectively. The main components identified from fraction 1, 2 and 3 were hentricontane (35.7%), ethyl hexadecanoate (21.7%) and linoleic acid (16.16%), respectively. Bioassay screening of oil showed moderate antibacterial activity against Salmonella group (Gram +ve and ?ve) by agar well diffusion method, moderate antifungal activity against Microsporum canis by agar tube dilution method and good antioxidant activity by DPPH radical scavenging method.     

Composition of the essential oils of Lycium barbarum and L. ruthenicum fruits

Water-distilled essential oils from the fruits of Lycium barbarum and L. ruthenicum were analyzed by GCMS. The main components in the oil of L. barbarum were found to be hexadecanoic acid (47.5%), linoleic acid (9.1%), β-elemene (5.4%), myristic acid (4.2%), and ethyl hexadecanoate (4.0%). The essential oil of L. ruthenicum has heptacosane (14.3%), ethyl linoleate (10.0%), hexacosane (7.0%), nonacosane (6.2%), and ethyl hexadecanoate (5.8%) as the main compounds. Published in Khimiya Prirodnykh Soedinenii, No. 1, pp. 20–21, January–February, 2006.     

Development and Application of Different Non-thermal Plasma Reactors for the Removal of Perfluorosurfactants in Water: A Comparative Study

Plasma Chemistry and Plasma Processing - The degradation of perfluorosurfactants (PFS), particularly of PFOS, has been studied in dielectric barrier discharge (DBD) and nano-pulse corona discharge...     

Numerical continuation of degenerate homoclinic orbits in planar systems

In this paper we develop numerical algorithms for the continuationof degenerate homoclinic connections in planar systems. We considerthe case where the equilibrium point has zero trace and twocases of higher-order degeneracies. The method we propose isable to continue homoclinic connections of order up to codimension-four.Application of the algorithm to four examples supports its validityand demonstrates its usefulness.     

Crosslinking of a polyester resin in the heated plain sheet copper mould

The crosslinking of the unsaturated polyester was studied by using experiments and a model of the process. The kinetic parameters were calculated from the heat flux–time curves obtained by differential scanning calorimetry (DSC, Netzsch–Simultaneous Thermal Analyser DSC 200), working in DSC (dynamic) mode. The temperature–time histories were studied in plain sheet copper mould. The mathematical model was constructed by taking into account the heat transferred by conduction through the resin, as well as the kinetics of heat generated by the crosslinking reaction. The contributions to the rise in temperature from heat conduction and chemical reaction are different in different parts of the composite, and can explain the temperature-, or degree of crosslinking (DOC)–time histories. By considering temperature–time histories developed within the sample, more extensive knowledge of the process can be obtained. The effect of the heat transfer by conduction through the composite as well as the internal heat generated by the cure reaction is clearly shown, despite the complexity of the process. Finally, good agreement between experimental data and predicted mathematical model of the crosslinking process in plane sheet mould was shown.     

Gas-phase deprotonation of arylalkylamines. A collision-induced dissociation study

The collision-induced dissociation (CID) of deprotonated arylalkylamines of general formula R(1)C(6)H(4)CHR(2)CH(2)NR(3)(2) (where R(1) = H, OH, F or NO(2); R(2) = H or OH; R(3) = H or CH(3)) generated by negative chemical ionization with H(2)O and D(2)O as ionizing reagents, is discussed. The negative chemical ionization mass spectra show that, in the absence of a hydroxy group in the aromatic ring, deprotonation takes place at the benzylic position whereas the proton is lost from the OH group when present. The nitro compound forms only M(-.) ions. The CID spectra of the deprotonated molecules show that fragmentations are strongly dependent on the structural features of the molecules, namely the presence or absence of substituents in the aromatic ring or aliphatic chain. Copyright 1999 John Wiley & Sons, Ltd.     

The onset of coulomb explosions in polyatomic molecules

With the development of high intensity femtosecond lasers, the ionisation and dissociation dynamics of molecules has become an area of considerable interest. Using the technique of femtosecond laser mass spectrometry (FLMS), the molecules carbon disulphide, pyrimidine, toluene, cyclohexanone and benzaldehyde are studied with pulse widths of 50 fs in the near infrared (IR) wavelength region (790 nm). Results are presented and contrasted for laser beam intensities around 10(15) and 10(16) W cm(-2). For the lower intensities, the mass spectra yield dominant singly charged parent ions. Additionally, the appearance of doubly charged parent ions is evident for carbon disulphide, toluene and benzaldehyde with envelopes of doubly charged satellite species existing in these local regions. Carbon disulphide also reveals a small triply charged component. Such atomic-like features are thought to be a strong fingerprint of FLMS at these intensities. However, upon increasing the laser intensity to approximately 10(16) W cm(-2), parent ion dominance decreases and the appearance of multiply charged atomic species occurs, particularly carbon. This phenomenon has been attributed to Coulomb explosions in which the fast absorption of many photons may produce transient highly ionised parent species which can subsequently blow apart. Copyright 1999 John Wiley & Sons, Ltd.     

Uniform molecular analysis using femtosecond laser mass spectrometry

The potential of femtosecond laser time-of-flight mass spectrometry (FLMS) for uniform quantitative analysis of molecules has been investigated. Various samples of molecular gases and vapours have been studied, using ultra-fast ( approximately 50 fs) laser pulses with very high intensity (up to 1.6 x 10(16) Wcm(-2)) for non-resonant multiphoton ionisation/tunnel ionisation. Some of these molecules have high ionisation potentials, requiring up to ten photons for non-resonant ionisation. The relative sensitivity factors (RSF) have been determined as a function of the laser intensity and it has been demonstrated that for molecules with very different masses and ionisation potentials, uniform ionisation has been achieved at the highest laser intensities. Quantitative laser mass spectrometry of molecules is therefore a distinct possibility. Copyright 1999 John Wiley & Sons, Ltd.