Stability of Triangular Libration Points in the Sun - Jupiter System under Szebehely’s Criterion

In the present study, the classical fourth-order Runge-Kutta method with seventh-order automatic step-size control has been carried out to examine the stability of triangular libration points in the Sun-Jupiter system. The Sun is a highly luminous body and Jupiter is a highly spinning body, so radiation pressure of the Sun and oblateness of the Jupiter cannot be neglected. These factors must have some effects on the motion of the infinitesimal mass (spacecraft) and consequent effects on the stability of the triangular libration points. It is to be noted that in our problem, infinitesimal mass exerts no influence of attraction on the primaries (Sun and Jupiter) but its motion is influenced by the primaries. Therefore, the equations of motion of the infinitesimal mass moving in the gravitational field of the radiating Sun and oblate Jupiter have been established for numerical integration. To check the stability of the libration points, the infinitesimal mass is allowed to librate for trajectory generation in the vicinity of one of the triangular libration points. Using double-precision computation, the Jacobian constant was calculated in order to observe the validity of the trajectory generation throughout the numerical integration. This constant of integration was checked to make sure that it remained constant at least to eight decimal places, so that other data may be accurate. Following all the above computational techniques, the maximum displacement and maximum velocity envelopes were constructed in the light of previous authors. The reason behind the assumption of the maximum displacement and maximum velocity envelopes is that the spacecraft (infinitesimal mass) will librate for a long time within the region of the envelopes without crossing the x-axis. If the area of the envelope is not maximum within the given time limit and the infinitesimal mass crosses the x-axis, then by changing the initial conditions; we attempt to construct the envelopes of maximum area following previous authors. If the area of the envelope is maximum it means spacecraft (infinitesimal mass) will librate in wider area for a long time without crossing the x-axis and longtime libration will give the higher range of stability. From our observation, it is found that due to the oblateness of Jupiter, the range of stability is reduced but photogravitation of the Sun has no significant effect on the triangular libration points

Collective Modes of Massive Dirac Fermions in Armchair Graphene Nanoribbons

We report the plasmon dispersion characteristics of intrinsic and extrinsic armchair graphene nanoribbons of atomic width N = 5 using a p_z-orbital tight binding model with third-nearest-neighbor (3nn) coupling. The coupling parameters are obtained by fitting the 3nn dispersions to that of an extended Huckel theory. The resultant massive Dirac Fermion system has a band gap E_g \approx 64 meV. The extrinsic plasmon dispersion relation is found to approach a common dispersion curve as the chemical potential $\mu$ increases, whereas the intrinsic plasmon dispersion relation is found to have both energy and momentum thresholds. We also report an analytical model for the extrinsic plasmon group velocity in the q \rightarrow 0 limit

Kinetics and Mechanism of Reduction of 4(p-Dimethylamino)-Benzylidene-3-Methyl-1-Phenyl-2-Pyrazolin-5-one by Bisulphite Ions in Aqueous Ethanolic Media

The kinetics of the title reduction studied in aqueous ethanolic media spectrophotometrically. The effect of hydrogen ion concentration on the reduction rate was investigated in buffer solutions at constant ionic strength of 1.0. The reaction was found to be of the first order in both reactants and inverse first order with respect to the hydrogen ion. The rate of the reaction decreased with increasing ethanol as well as hydrogen ion concentrations. Pseudo-first-order rate constant, kob was obtained by monitoring the disappearance of the [dye]. Activation parameters have been evaluated and a tentative reaction mechanism was discussed

Armchair graphene nanoribbons: Electronic structure and electric field modulation

We report electronic structure and electric field modulation calculations in the width direction for armchair graphene nanoribbons (acGNRs) using a semi-empirical extended Huckel theory. Important band structure parameters are computed, e.g. effectives masses, velocities and bandgaps. For the three types of acGNRs, the pz orbital tight-binding parameters are extracted if feasible. Furthermore, the effect of electric field in the width direction on acGNRs dispersion is explored. It is shown that for the two types of semiconducting acGNRs, an external electric field can reduce the bandgap to a few meV with different quantitative behavior.Comment: 5 pages, 5 figure

In-vitro application of a qatari burkholderia cepacia strain (QBC03) in the biocontrol of mycotoxigenic fungi and in the reduction of ochratoxin a biosynthesis by aspergillus carbonarius

Mycotoxins are secondary metabolites produced by certain filamentous fungi, causing human and animal health issues upon the ingestion of contaminated food and feed. Among the safest approaches to the control of mycotoxigenic fungi and mycotoxin detoxification is the application of microbial biocontrol agents. Burkholderia cepacia is known for producing metabolites active against a broad number of pathogenic fungi. In this study, the antifungal potential of a Qatari strain of Burkholderia cepacia (QBC03) was explored. QBC03 exhibited antifungal activity against a wide range of mycotoxigenic, as well as phytopathogenic, fungal genera and species. The QBC03 culture supernatant significantly inhibited the growth of Aspergillus carbonarius, Fusarium culmorum and Penicillium verrucosum in PDA medium, as well as A. carbonarius and P. verrucosum biomass in PDB medium. The QBC03 culture supernatant was found to dramatically reduce the synthesis of ochratoxin A (OTA) by A. carbonarius, in addition to inducing mycelia malformation. The antifungal activity of QBC03’s culture extract was retained following thermal treatment at 100 °C for 30 min. The findings of the present study advocate that QBC03 is a suitable biocontrol agent against toxigenic fungi, due to the inhibitory activity of its thermostable metabolites. View Full-TextFunding: Qatar National Research Fund (a member of Qatar Foundation) under National Priorities Research Program (NPRP) grant #NPRP8-392-4-003.Scopu

Electrochemical treatment of Poultry Slaughterhouse Wastewater using Iron and Aluminium Electrodes

Electrochemical process for the treatment of poultry slaughterhouse wastewater (PSWW) was studied. The effects of some key factors such as initial pH, current density, operating time and the kind of electrodes on the removal of chemical oxygen demand (COD), oil and grease, total suspended solids (TSS), total kjeldahl nitrogen (TKN) and total phosphors (TP) were investigated. It is clear that the process has a good efficiency. The highest removal amount of COD (95.6) was achieved with aluminium electrode (pH value between 2 and 3 and charge passed 20.34x10(3) colons (current density 0.014 A cm(-2)). 95.3 of oil and grease was removed in the same conditions, of course, in the case of iron electrode. The maximum removal efficiency for TKN and TP were 77.8 and 89.6 respectively (pH 3, charge passed 30.51x10(3) colons and with aluminium). Consequently electrocoagulation is comparatively suitable process for PSWW treatment