Mapping the Stability Diagram of a Quadrupole Mass Spectrometer with a Static Transverse Magnetic Field Applied

Previous experimental and theoretical work identified that the application of a static magnetic (B) field can improve the resolution of a quadrupole mass spectrometer (QMS) and this simple method of performance enhancement offers advantages for field deployment. Presented here are further data showing the effect of the transverse magnetic field upon the QMS performance. For the first time, the asymmetry in QMS operation with B _x and B _y is considered and explained in terms of operation in the fourth quadrant of the stability diagram. The results may be explained by considering the additional Lorentz force (v x B) experienced by the ion trajectories in each case. Using our numerical approach, we model not only the individual ion trajectories for a transverse B field applied in x and y but also the mass spectra and the effect of the magnetic field upon the stability diagram. Our theoretical findings, confirmed by experiment, show an improvement in resolution and ion transmission by application of magnetic field for certain operating conditions.

An Experimentally Convenient Preparation of Highly Substituted Pyridines

A four step sequence is described for the conversion of α,β-unsaturated carboxylic acids into highly substituted pyridines.     

Gas-phase thermolysis of condensed-1,2,4-triazines: interesting routes toward heterocyclic ring systems

Gas-phase thermolysis of thieno[2,3-e][1,2,4]triazines gave benzonitrile, isothiazole, pyridazine, and thieno[2,3-d]thiazole derivatives. Similar transformation of benzo[1,2,4]triazine and phenanthro[9,10-e][1,2,4]triazine derivatives into their corresponding condensed thiazoles has been achieved by heating at 350 °C with sulfur. A mechanism for these pyrolytic transformations was proposed.     

Determination of total phosphorus and nitrogen in turbid waters by oxidation with alkaline potassium peroxodisulfate and low pressure microwave digestion, autoclave heating or the use of closed vessels in a hot water bath: comparison with Kjeldahl digestion

The evaluation of the use of alkaline peroxodisulfate digestion with low pressure microwave, autoclave or hot water bath heating for the determination of total phosphorus and nitrogen in turbid lake and river waters is described. The efficiency of these digestion procedures were compared to a Kjeldahl digestion procedure with sulphuric acid-potassium sulfate and copper sulfate. The final solution before digestion was 0.045 M in potassium peroxodisulfate and 0.04 M in sodium hydroxide. Procedures were evaluated by the analysis of suspensions of two reference materials, National Institute of Environmental Science, Japan, no. 3 Chlorella and no. 2 pond sediment and natural turbid waters. Best recoveries of phosphorus and nitrogen by microwave heating were obtained when solutions were digested at 95 °C for 40 min. Quantitative recoveries of phosphorus from Chlorella suspensions up to 1000 mg/l were obtained by all three heating procedures, but incomplete recoveries of nitrogen occurred above 20 mg N/l in the digested sample. Good recoveries of phosphorus and nitrogen from suspended sediment suspensions were obtained only from solutions containing <150 mg/l of suspended sediments. Recoveries of phosphorus from phosphorus compounds containing COP and CP bonds added to distilled water were quantitative (94-113%) except for polyphosphates (microwave, 34±8; autoclave, 114±6; water bath, 96±4) and aluminium phosphate (8-23%). Recoveries of nitrogen compounds containing CN bonds added to distilled water were quantitative (94-96%). The analysis of a range of natural turbid water samples by alkaline peroxodisulfate and microwave, autoclave and water bath heating gave similar total phosphorus and nitrogen results. All procedures using alkaline peroxodisulfate underestimate phosphorus concentrations at high suspended sediment concentrations (>150 mg/l) and are only suitable for the analysis of very turbid samples when the turbidity is due to organic matter (algal cells, plant detritus). Underestimation of nitrogen occurs when samples contain more than 20 mg N/l.     

Emodin,A Naturally Occuring Anthraquinone: Its Isolation and Spectrophotometric Determination in Rumex Cyprius Plant

A new method for isolation and specrophotometric determination of emodin is presented. Emodin was isolated by thin layer chromatography (tlc) and column chromatography (cc) techniques, as an orange long crystalline substance. Emodin exhibits two absorption maxima, at 420 and 520 nm. Stability of the color and the effect of pH were studied. Beer's law is obeyed in the range 2–30 ppm.

The method is applied to the determination of emodin in roots, stems, and leaves of Rumex cyprius plant.     

Dynamics of chelation-supercritical fluid extraction from wood fibers

The dynamics of supercritical fluid extraction (SFE) of the metal content of wood fibers chelated with lithium bis(trifluoroethyl) dithiocarbamate (FDDC) by supercritical (SF) CO2 was investigated experimentally by monitoring the spectra of the eluted metal complex as a function of time. The characteristic shape of the dynamic SFE curve was determined mainly by the flow conditions in the extraction vessel, the mass transfer resistance in the SF phase, and the solubility. High extraction yields of metal content were obtained in two-stage extraction including static (batch) and dynamic (semi-batch) stages. Increasing the length of the static stage increased the rate of dynamic elution of metal complex until it approached the dynamics of fluid displacement for a continuous stirred tank reactor (CSTR). In such cases, increasing the flow rate had no effect on the dynamic extraction curve when it was plotted using dimensionless time. Efficient chelation-SFE from wood fibers was obtained at a pressure of 20.3 MPa and with a static time of 30 min.     

To breathe or not to breathe—That is the question: An investigation of speech breathing kinematics in world class Shakespearean actors

Anteroposterior diameter changes of the rib cage and abdomen were recorded during respiratory and speaking activities in four adult subjects, three men and one woman, all of whom had extensive dramatic training and experience and were earning their livelihood as professional actors. Data were charted to solve for lung volume, and volume displacements of the rib cage and abdomen. The more vigorous and louder monologue performances by the professional actor subjects differed from other speaking and reading activities in the following parameters of lung volume, separate volumes, relative volume contributions, and the frequent use of respiratory phase transitions. Novice actor subjects' monologue performances are compared to the monologue performances of the professional actor subjects.