Showing papers by "Jadavpur University published in 1969"

Isolation and characterization of a toxin from the Florida red tide organism.

Abstract: EVIDENCE for a causal relationship between blooms of the Florida red tide organism, Gymnodinium breve Davis, and mass mortalities of marine animals seems well established1. In most cases the mortalities can be ascribed to a toxin which has been isolated from a bloom, as well as from laboratory cultures of G. breve1,2. Other studies have been concerned with physiological and some chemical properties of the toxin2–6.

The Deformable Shell Model Calculation of Infrared Absorption Frequencies of Ionic Crystals

Abstract: The deformable shell model which includes many-body effects and accounts for the breakdown of Cauchy relation is extended to the case of the CsCl structure. The TO mode frequencies for q = 0 are calculated for eight ionic crystals of both NaCl and CsCl structures. For comparison, the shell model values are also calculated. The results are compared with the infrared absorption frequencies. It is found that the deformable shell model gives better agreement than the shell model. The result is particularly striking for crystals showing a large Cauchy relation breakdown. Das deformierbare Schalenmodell, das Vielteilcheneffekte einschliest und fur das Versagen der Cauchy-Beziehung verantwortlich ist, wird auf den Fall der CsCl-Struktur ausgedehnt. Die Frequenzen der TO-Schwingungsmode fur q = 0 werden fur acht Ionenkristalle sowohl der NaCl- als auch der CsCl-Struktur berechnet. Zum Vergleich werden auch die Werte des Schalenmodells berechnet. Die Ergebnisse werden mit den Infrarotabsorptionsfrequenzen verglichen. Es wird gefunden, das das deformierbare Schalenmodell bessere Ubereinstimmung als das Schalenmodell gibt. Die Ergebnisse sind besonders gut fur Kristalle, die ein starkes Versagen der Cauchy-Beziehung zeigen.

Separation and Quantitation of Neomycins as Free Base by Paper Chromatography

Abstract: Neomycin B and C and neamine were separated as free bases in the solvent system methyl ethyl ketone- tert -butyl alcohol-methanol-6.5 N NH 4 OH (16:3:1:6 v/v) and quantitatively estimated. Images

Estimation of the film thickness from the cohesive pressure at the air water interface

Abstract: The pressure-area curves for neutral monolayers of butyric, valeric, caproic and caprylic acids at the airwater interface were obtained from the surface tension concentration data. Similar curves for the charged monolayers of sodium octanoate and sodium lauryl sulphate in the presence and absence of excess neutral salts were constructed on the basis of the results on surface tension. From the comparison of the pressure area curves of each of these monolayers at air-water and oil-water interfaces under identical conditions, the cohesive pressures of the monolayer at the air-water interface were calculated for different areas per adsorbed molecule using the equation ofDavies. The cohesive pressure was observed to vary linearly with the square of the reciprocal area per adsorbed molecule or ion. From the slope of such linear plot, magnitude of the two-dimensionalvan der Waals constant in each case was estimated. The thickness of the interfacial film was estimated from the comparison of the values of two- and three-dimensionalvan der Waals constants. This is, however, found to be considerably greater than the length of the stretched molecules adsorbed at the interface. When correction for entropy, as suggested byGershfeld is introduced, the film thickness becomes identical with the length of the molecule.

Absorption of sodium lauryl sulphate at the benzene-water interface

Abstract: The interfacial tension of benzene-water interface was measured as a function of sodium lauryl sulphate concentration in presence of 0, 0,1 and 1 M sodium chloride. Analysis of pressure-area curves constructed from these data indicated qualitatively the validity of the ‘onekT’ and ‘twokT’ forms of theGibbs equation respectively for the presence and absence of neutral salt. The proposed dimerisation of lauryl sulphate ions in the bulk was shown not to affect theΠ- A curves to a large extent in the high pressure region. The limiting area per adsorbed ion was evaluated from an empirical plot. The experimental pressure was found to deviate significantly from that expected theoretically from theGouy model of the electrical double layer. This deviation was explained on the basis of the “discrete-ion-effect” proposed byBell, Levine andPethica.

Input impedance and radiation efficiency of a center-fed dipole antenna with feed points displaced transverse to dipole axis

Abstract: A generalized analysis of a center-fed dipole antenna with feed points displaced transverse to the dipole axis is presented. Mathematical expressions for the near-zone field radiation are developed from which the input impedance integral is obtained. The theoretical investigation of the radiation efficiency of the same antenna is also made.

Constructing normal-mode helical antennas

Abstract: Helical antennas have made a marked impression on the communications industry due to the growing demands of telemetering, command and control and communications in the aircraft and guided-missile field. Helical antennas in the above fields are always circularly polarized and act in the axial mode. Compared to the axial-mode helical antennas, little attention has been paid to normal-mode helical antennas because of small bandwidth and low efficiency. However, it has been found recently1 that normal-mode helical antennas have certain considerations which far outweigh their disadvantages. These considerations are height reduction, ease of installation, and cost. It has been suggested1 by the author and his co-workers that it is quite possible to use normal-mode helical antennas in the medium and short wave region, thereby reducing the height of the mast antenna by a factor of 5 to 10. This paper discusses in detail the design and construction of vertically polarized normal-mode helical antenna structures.

Ideal equation of state for charged monolayer at the liquid interface

Abstract: An attempt has been made to estimate the value of the kT -coefficient of the ideal equation of state for the charged monolayer in the presence and absence of the neutral salt. Guggenheim's concept of the surface phase is taken as the basis for such calculation. The value of the kT -coefficient has been found to be “two” both in the presence and absence of the neutral salt when integrated forms of the Boltzmann equations are used for the calculation of the surface concentrations of the inorganic ions. The result is in agreement with that previously suggested by Phillips and Rideal. However, if the nonintegrated forms of the Boltzmann equations are used for this calculation, p is found to be much less than two in agreement with the expectation of Davies.

A temperature-stable RC transistor oscillator

Abstract: Generation of stable sinusoidal oscillations of fairly good waveform has been realized in a basic multivibrator circuit by optimizing load and coupling elements and introducing an amplitude defining mechanism with the use of emitter coupling. The resulting differential operation introduces an inherent tendency of self-compensation against changes of active circuit parameters, and the frequency remains practically independent of temperature change even though transistors are used.

Models of electrical double layer and gibbs equation for adsorption of electrolytes

Abstract: A general expression for the kT-coefficient of the Gibbs equation is initially obtained without introducing any model of double layer. In order to calculate n Cl − n Na + in this expression, the Helmholtz, Gouy, Stern, and penetration double-layer models have been used successively. The counter-ion binding in the surface and bulk phases for the adsorption of the polyelectrolytes and charged micelles is also considered in detail.

A stable square-wave generator†

Abstract: A square-wave generator with a frequency stability of the order of 10−3 is described. The circuit is basically a difference amplifier with cross-coupling feedback connections to generate stable relaxation oscillation. Output waveform is sharp even at sub-audio frequencies and the wave shape is not seriously affected by resistive or capacitive loads.

Investigations on normal mode helices

Abstract: Axial mode helical antennae are well known for many applications. Compared with thorn, little attention has been paid to normal mode helical antennae. However, it has boon found recently that normal mode helices have wide applications in different fields—some of which have been investigated by the author and his co-workers and may be summarized as follows. (a) A log periodic antenna has been designed using normal mode helices as elements and its impedance and radiation characteristics have been measured. This study reveals that a helical log periodic antenna is electrically equivalent to a log periodic dipole antenna with the advantage that the former has a much reduced height (reduction factor being 0·22 in our case). (b) Investigations have been made to study the feasibility of using normal mode helical antennae in the medium and short wave regions. Experimental results indicate that it is quite possible to reduce the height of the mast antenna by a factor of 5 to 10 and the bandwidth is enough for the ...

A wide-range triangular waveform generator†

Abstract: A triangular waveform generator that operates over a wide range of frequency is described. A complementary pair of transistors are employed to charge and discharge a capacitor alternately in a linear manner in conjunction with a comparator and a level transforming circuit to generate symmetrical waveforms. The circuit configuration provides excellent amplitude stability.

Effect of methyl amphetamine on the brain 5-hydroxytryptamine content of isolated and aggregated rats

Abstract: Amphetamin bewirkt eine Vermehrung von 5-Hydroxytryptamin im Gehirn von aggregierten Ratten, wahrend Chlorpromazin diesen Effekt hemmt.

A current controlled magnetic multivibrator

Abstract: A new approach towards a magnetic amplifier is to treat it as a non-linear variable differentiating network having a controllable time constant. Such a differentiator, used in conjunction with an amplifier and a clipper, generates square waves over a wide range of frequency. The frequency of oscillation is dependent on the ro-set characteristics of the cores. The frequency versus control current characteristic has three widely separated zones and switching from one frequency level to the other may be accomplished by a small d.c. signal or a pulse.

On disturbances in a visco-elastic medium of Maxwell type in contact with a liquid medium and subjected to a magnetic field

Abstract: The problem of disturbances in a visco-elastic medium due to Maxwell in contact with a liquid medium — both being perfectly conductive — has been investigated when an impulsive force acts along the plane of the contact. The electro-magnetic equations of Maxwell, equation of elasticity and the stress-strain relations of the material have been used in the investigation.

Petrological Studies of Coals from East Bokaro Coalfield, Bihar

Abstract: Coals from two major seams viz., Karo and Bermo seams, East Bokaro Coalfield, Bihar were washed in the laboratory at different specific gravity medium. Chemical and petrological analyses of unwashed coals and the washed fractions from these were undertaken. Reflectance measurements (by Seyler's method) were made on the vitrinites for the unwashed coals and for different Iloat fractions after washing. The clean coals show an improved assemblage of macerals and reflecting components from the point of view of their physical and coking properties. It is also noticed that at 1.50 to 1.55 specific gravity cuts, the floats show a good reduction in ash content and a definite concentration of vitrinite and reflecting components, responsible for developing better coking characters. It is further observed that the coals from bottom section of the Bermo seam is more amenable to cleaning than the coal from the top section.

Hydroxy Sulfonated Fatty Acid Esters as Surface Active Agents III: Kinetics of the Synthesis

Abstract: Kinetics of synthesis of a new type of surface active agents having the general formula RCOOCH2CHOHCH2SO3M, where M is an alkali metal or other basic radical, have been studied Synthesis of hydroxy sulfonated fatty acid esters of oleic and lauric acids by the reaction of molar proportion of sodium chlorohydroxy propane sulfonate with fatty acid soap (formed in situ) was found to be a pseudo-first order reaction The energy of activation was calculated from Arrhenius equation as 257 kcal/mole Paper chromatographic method has also been used for kinetic studies Sulfonierte Fettsaureester als oberflachenaktive Stoffe III: Reaktionskinetik bei der Synthese Die Reaktionskinetik bei der Synthese eines neuen Typs von oberflachenaktiven Stoffen der allgemeinen Formel RCOOCH2 CHOHCH2SO3M (M = Alkalimetall) wurde untersucht Die Synthese der sulfonierten Ester der Ol- und Laurinsaure durch Reaktion zwischen molaren Mengen von Natriumchlorhydroxypropansulfonat und den im Reaktionsgemisch selbst erzeugten Seifen der Fettsauren verlief nach pseudo-erster Ordnung Die nach der Arrhenius'schen Gleichung berechnete Aktivierungsenergie betrug 257 kcal/Mol Auch die Papier-Chromatographie wurde bei der kinetischen Untersuchung angewandt

On the analysis of ladder networks

Abstract: Simple formulas for quick and easy calculation of the transfer characteristics of a specific kind of ladder network have been developed starting from the Fibonacci relationship of the network. Examples calculating the characteristics are also given.

Coupled linearly tapered transmission line directional coupler

Abstract: A coupled linearly tapered transmission line directional coupler has been analysed and an asymmetrical directional coupler is shown to possess high pass characteristics.

On magnetoelastic disturbances in an aelotropic elastic cylinder placed in a magnetic field

Abstract: The present note deals with the disturbances in an aelotropic elastic cylinder placed in an axial magnetic field, being acted upon by a mechanical force.

Hydroxy Sulfonated Fatty Acid Esters as Surface Active Agents IV: Surfactants from Mixed Fatty Acids of Fish, Rice Bran and Cottonseed Oils

Abstract: The preparation and properties of a few surface-active sulfonated monoglycerides derived from fish-, rice bran- and cottonseed oils are reported. An der Hydroxylgruppe sulfonierte Fettsaureester als oberflachenaktive Stoffe IV: Tenside aus Gesamtfettsauren des Fisch-, Reiskleie- und Baumwollsaatoles Es wird uber die Darstellung und Eigenschaften einiger oberflachenaktiver Monoglyceridsulfonate berichtet, die aus Fisch-, Reiskleie- und Baumwollsaatol hergestellt wurden.

Rayleigh-waves on cylindrical surfaces of aelotropic elastic material in a magnetic field

Abstract: Axial Rayleigh-waves in a magnetic field are considered for an elastic cylinder of aelotropic material, surrounded by a vacuum and for an infinite body of same material with cylindrical cavity.