A titrimetric method for the determination of tetra-alkylthiuram disulphides by oxidation with chloramine-T

An analytical method for the determination of tetra-alkylthiuram disulphides has been developed, based on the quantitative oxidation of carbon disulphide produced by acidified chloramine-T to sulphuric and formic acids. Twenty-eight equivalents of chloramine-T are required per mole of a thiuram disulphide.

A volumetric method for the determination of sulphoxides

A volumetric method for the quantitative determination of Sulphoxides has been developed, based on their oxidation to sulphones by dichromate in presence of 5 M sulphuric acid at 105–110°C. Excess dichromate is titrated by ferrous ammonium sulphate solution. The method is also applicable to the determination of Sulphoxides in metal sulphoxide complexes.

Ring loading of a long, thin, circular cylindrical shell enclosing a soft, solid core: A recalculation by the love function method of elasticity.

The problem is solved using the Love function and Flügge shell theory. Numerical work has been done with a computer for various values of shell geometry parameters and elastic constants.

A colorimetric method for the estimation of phloroglucinol

1. 1. A simple method has been devised for the estimation of phloroglucinol based on the formation of an intense colored compound with a modified Ehrlich reagent in the presence of trichloroacetic acid. Some factors affecting the formation of color have been studied. 2. 2. Careful regulation of trichloroacetic acid content in the system permits its estimation in 1–15 μg in the micro range and in 10–50 μg in the macro range. Phloroglucinol lends itself to ready separation by paper chromatography and estimation after clution from paper.

A new method for the titrimetric determination of perchlorate

A new method for the titrimetric determination of perchlorate has been developed, based on its reduction to chloride by iron(II) in a strong sulphuric acid medium at high temperature. The effect of variables, such as the sulphuric acid concentration, the temperature and the period of heating, on the extent of reduction has been studied and the optimal conditions for analytical determination of perehlorate derived.

Detection of a periodic structure hidden in random background: the role of signal amplitude in the matched filter detection method

The matched filter method for detecting a periodic structure on a surface hidden behind randomness is known to detect up to (r(0)/Lambda) gt;= 0.11, where r(0) is the coherence length of light on scattering from the rough part and 3 is the wavelength of the periodic part of the surface-the above limit being much lower than what is allowed by conventional detection methods. The primary goal of this technique is the detection and characterization of the periodic structure hidden behind randomness without the use of any complicated experimental or computational procedures. This paper examines this detection procedure for various values of the amplitude a of the periodic part beginning from a = 0 to small finite values of a. We thus address the importance of the following quantities: `(a)lambda) `, which scales the amplitude of the periodic part with the wavelength of light, and (r(0))Lambda),in determining the detectability of the intensity peaks.

Transduction in mycobacterium smegmatis

SEVERAL people have studied lysogeny and lysogenic conversion in the advanced prokaryote, Mycobacterium1-3, and presented evidence for reciprocal genetic exchange from the lysogenic to the non-lysogenic state. Biochemical and physiological changes induced by lysogenization of M. phlei with mycobacteriophage B2 have been demonstrated by Juhasz4. We wish to report the isolation of a mycobacteriophage capable of mediating transduction in Mycobacterium smegmatis strain SN2, thus providing an opportunity to study the genetics of mycobacteria.

A colorimetric method for determination of pyrocatechol and related substances

A colorimetric assay for the quantitative determination of catecholic compounds was developed. The method was based on the observation that a red color was formed when nitrite was added to a solution containing pyrocatechol and sodium tungstate. Aromatic amines interfere with the reaction but this could be overcome by the addition of formaldehyde. When interfering substances are present along with pyrocatechol, it can be readily separated by paper chromatography and estimated after elution from the filter paper.

A method for the preferential isolation of actinomycetes from soils

A successful plate-method for the preferential isolation of actinomycetes from soils is described. The principles underlying it are: (1) the inhibition of growth of non-sporulating bacteria by pre-incubation at a high temperature (110 C) for 10 min, and (2) limiting the spreading growth of sporeforming bacteria and fungi by the use of dried plates. The majority of the 191 species isolated by this method from 82 soil samples were shown to be pectinolytic.

Top Quark Mass Measurement in the lepton+jets Channel Using a Matrix Element Method and in situ Jet Energy Calibration

A precision measurement of the top quark mass m_t is obtained using a sample of ttbar events from ppbar collisions at the Fermilab Tevatron with the CDF II detector. Selected events require an electron or muon, large missing transverse energy, and exactly four high-energy jets, at least one of which is tagged as coming from a b quark. A likelihood is calculated using a matrix element method with quasi-Monte Carlo integration taking into account finite detector resolution and jet mass effects. The event likelihood is a function of m_t and a parameter DJES to calibrate the jet energy scale /in situ/. Using a total of 1087 events, a value of m_t = 173.0 +/- 1.2 GeV/c^2 is measured.

Top quark mass measurement in the lepton plus jets channel using a modified matrix element method

We report a measurement of the top quark mass, m_t, obtained from ppbar collisions at sqrt(s) = 1.96 TeV at the Fermilab Tevatron using the CDF II detector. We analyze a sample corresponding to an integrated luminosity of 1.9 fb^-1. We select events with an electron or muon, large missing transverse energy, and exactly four high-energy jets in the central region of the detector, at least one of which is tagged as coming from a b quark. We calculate a signal likelihood using a matrix element integration method, with effective propagators to take into account assumptions on event kinematics. Our event likelihood is a function of m_t and a parameter JES that determines /in situ/ the calibration of the jet energies. We use a neural network discriminant to distinguish signal from background events. We also apply a cut on the peak value of each event likelihood curve to reduce the contribution of background and badly reconstructed events. Using the 318 events that pass all selection criteria, we find m_t = 172.7 +/- 1.8 (stat. + JES) +/- 1.2 (syst.) GeV/c^2.

Measurement of the top quark mass at CDF using the “neutrino ϕ weighting” template method on a lepton plus isolated track sample

We present a measurement of the top quark mass with t-tbar dilepton events produced in p-pbar collisions at the Fermilab Tevatron $\sqrt{s}$=1.96 TeV and collected by the CDF II detector. A sample of 328 events with a charged electron or muon and an isolated track, corresponding to an integrated luminosity of 2.9 fb$^{-1}$, are selected as t-tbar candidates. To account for the unconstrained event kinematics, we scan over the phase space of the azimuthal angles ($\phi_{\nu_1},\phi_{\nu_2}$) of neutrinos and reconstruct the top quark mass for each $\phi_{\nu_1},\phi_{\nu_2}$ pair by minimizing a $\chi^2$ function in the t-tbar dilepton hypothesis. We assign $\chi^2$-dependent weights to the solutions in order to build a preferred mass for each event. Preferred mass distributions (templates) are built from simulated t-tbar and background events, and parameterized in order to provide continuous probability density functions. A likelihood fit to the mass distribution in data as a weighted sum of signal and background probability density functions gives a top quark mass of $165.5^{+{3.4}}_{-{3.3}}$(stat.)$\pm 3.1$(syst.) GeV/$c^2$.