Subrata Chattopadhyay

A low-cost noncontact capacitance-type level transducer for a conducting liquid

In this paper, an attempt has been made to design a low-cost noncontact capacitance-type level sensor for a conducting liquid. The sensor is in the form of a uniform circular cylinder made of insulating material like glass, ceramic, plastic, etc. The sensor is connected with the metallic- or nonmetallic-type liquid storage tank, in which the conducting liquid column is taken as one electrode, and a noninductively wound short-circuited outside coil is taken as the other electrode of a variable capacitor. The change in capacitance due to the change of liquid level is measured by a modified linear operational-amplifier-based De Sauty bridge network with adjustable bridge sensitivity. The bridge output after amplification and rectification may be used to drive a direct current indicator calibrated in level. The studies have been made with high-density polyethylene and glass tube sensors separately in both metallic and nonmetallic storage tanks with tap water as the conducting liquid, and the experimental results of the static characteristics of the level sensors with percentage error from linearity are presented in the paper. These results are found to have good linearity and repeatability within acceptable limits

Reactivation of denatured fungal glucose 6-phosphate dehydrogenase and E. coli alkaline phosphatase with E. coli ribosome

Fungal glucose 6-phosphate dehydrogenase and E. coli alkaline phosphatase were denatured either by physical or by chemical means. In vitro reconstitution of these denatured enzymes was assisted by 70S E. coli ribosome, as shown by the recovery of their catalytic competence. Almost total recovery of the activities of completely inactivated enzymes was obtained when 70S ribosome was present at about equimolar concentration with the enzyme molecules at 37C and 50C, respectively.

Modification of the Maxwell–Wien Bridge for Accurate Measurement of a Process Variable by an Inductive Transducer

The small inductance of an inductive transducer generally linearly changes with a process variable, but their measurement by the usual inductive bridge circuit like the Maxwell bridge, the Maxwell-Wien Bridge, the Hay bridge, etc., suffers from errors due to the effect of the stray capacitance between bridge nodal points and the ground and the stray inductance on the inductive coil, respectively. The conventional Wagner-Earth technique is not suitable for continuous measurement. In this paper, a modified operational-amplifier-based Maxwell-Wien bridge measurement technique has been proposed in which the effect of stray capacitance and inductance is minimized. In the first phase of the experiment, the bridge performance has been studied with a known variable inductor, and in the second phase, the same experimentation was done by replacing the variable inductor with an inductive coil having an adjustable core position for the measurement of displacement. The linear characteristics over a wide range of displacement with good repeatability, linearity, and variable sensitivity have been described.

Thielavia indica sp.nov.

Thielavia indica sp.nov. isolated from the soil of paddy fields of State Agricultural Farm, Chinsurah, India, is described. It differs from other species of Thielavia in having sixteen ascospores in each ascus instead of eight. Thielavia indica sp.nov. (Fig. 1) Coloniae moderate crescentes in ‘potato-dextrose agar’, primum albidae, turn evadentes pallide, roseae vel pallide roseo-violaceae. Hyphae diametri variabilis, 0·8−4 μ , septate, ramosae, tenuiores quidem hyalinae, latiores vero olivaceae colore. Cleistothecia immersa in medium, globosa vel subglobosa, sessilia, absque ullo appendice, nigra, parietibus pseudo-parenchymaticis, membranacea, 1−3 seriebus constituta, magnit. 178·8−650 μ , longitudine, 162·5−405·8 μ latitudine. Asci plures, dispersi ovales vel pyriformes, nonpedicellati, tenuibus parietibus praediti, magnit. 14·8−12·8 × 3·2−5·6 μ . Ascosporae 16 in singulis ascis, irregulariter dispositae, ovatae vel oblongae, semel cellulatae, fusce brunneae, crassis parietibus praeditae, leves, magnit. 4·8−12·8 × 3·2−5·6 μ . Typus lectus in humo in orizetis in State Agricultural Farm, in loco Chinsurah, in provincia West Bengal in India (Herb. I.M.I. 57849).

Arachniotus indicus sp.nov.

Arachniotus indicus sp.nov. from the soil of paddy fields of State Agricultural Farm, Chinsurah, India, is described. A. indicus var. major var.nov. differing from the type species in the size of the cleistothecium, coloration and structure of the wall of the peridium is also described.