Showing papers by "University of Huddersfield published in 1977"

Entropy, Binding Energy, and Enzymic Catalysis†

Abstract: Why are enzyme-catalyzed reactions so much faster than uncatalyzed reactions, and why are enzymes so specific? What is the effect of mere approximation of enzyme and substrate, and what is the influence of the strain energy? Attempts to answer these questions have led to comparisons between entropy changes in intermolecular and intramolecular reactions, and to determinations of the intrinsic energy of the bond arising by non-covalent interaction between enzyme and substrate

Heterocellular Hereditary Persistence of Fetal Haemoglobin (Heterocellular HPFH) and its Interaction with β Thalassaemia

Abstract: Summary. Three families have been observed in which a gene for heterocellular hereditary persistence of fetal haemoglobin (HPFH), probably identical to that previously described as Swiss type HPFH, has been inherited together with β thalassaemia. The interaction of these two genes results in β thalassaemia heterozygotes with unusually high levels of fetal haemoglobin, 6–15%, heterogeneously distributed. In four individuals with Hb S-β thalassaemia who also inherited a heterocellular HPFH gene, Hb F levels of up to 25% were observed, resulting in an extremely mild clinical condition. Globin synthesis studies show less chain imbalance in the heterocellular HPFH-β thalassaemia compound heterozygotes than in the heterozygous β thalassaemia members of these families. Age stratification of the red cells by centrifugation showed enrichment of Hb F and Hb F-containing cells (F-cells) in the older cell population. It is suggested that the effect of the heterocellular HPFH gene is to increase the size of the F-cell population and that preferential survival of that expanded F cell population leads to the high levels of Hb F which result when heterocellular HPFH interacts with β thalassaemia or Hb S. The mild clinical condition which results from such interaction may explain part of the heterogeneity of the β thalassaemia syndromes and suggests that the induction of even relatively small increases in the production of Hb F in these conditions could be of potential therapeutic benefit.

Encoding in senile dementia and elderly depressives: A preliminary study

Abstract: Forty-seven subjects (19 elderly dements, 18 elderly depressives, 10 elderly physically ill) were given a continuous false recognition technique (FRT) in a test battery including a measure of short-term memory and the Kendrick Synonym Learning Test. Results were analysed according to signal detection theory and interpreted in terms of an encoding breakdown. Depressives were found to be characterized by conservative error-free performance whereas the demented made more errors, partly because of their more liberal criterion and partly because of their greater loss of encoding characteristics. From these results, an optimal cut-off score was chosen for differential dignosis using the FRT. This was shown to hold more promise than the SLT in discriminating between dementia and depression.

Entropie, Bindungsenergie und enzymatische Katalyse

Abstract: Warum verlaufen enzymkatalysierte Reaktionen so viel schneller als unkatalysierte Reaktionen, und warum wirken Enzyme so spezifisch? Welchen Einflus hat die blose Annaherung von Enzym und Substrat, und wie wirkt sich die Spannungsenergie aus? Um diese Fragen zu beantworten, wurden u. a. Entropieanderungen bei intermolekularen und intramolekularen Reaktionen miteinander verglichen und die Innere Energie der Bindung bestimmt, die durch nichtkovalente Wechselwirkung von Enzym und Substrat zustandekommt.

Final drive gearing with brake

Abstract: A final drive assembly for an agricultural tractor has a casing in which are journalled the outer end of a half-shaft and, parallel to the half-shaft, a final drive shaft. The two shafts are driveably interconnected by fixed ratio speed reduction gearing lubricated by mineral oil contained in the casing. A multi-disc brake can frictionally interconnect the half-shaft and the casing, and is operated via a linkage by a hydraulic slave cylinder housed within the casing and preferably actuated by mineral oil to avoid contaminating the lubricating oil in the event of any leakage from the cylinder.

Scroll discharge decanter centrifuges

Abstract: The invention concerns scroll discharge decanter centrifuges of the type in which the interior of the centrifuge is to be kept sealed from the atmosphere and which comprise a stationary assembly which includes an outer casing, a rotary assembly which includes a solid bowl which is adapted to be rotated within the stationary casing at a first speed and a scroll conveyor which is rotatable within the bowl at a second, slightly different speed. A plurality of sealing devices are arranged to be effective between the rotary assembly and the stationary assembly. Each sealing device comprises a first ring fixed relative to the stationary assembly and a second, coaxial ring which is adapted to rotate with the rotary assembly. That surface of the first ring which faces the second ring contains a plurality of gas jet nozzles by way of which pressurized gas can be supplied to an annular clearance gap between the first and second rings. One of the rings of each bearing is sealed by means of one or more elastomeric seals to a further annular member which is stationary relative to that one ring such that that ring is permitted to have a predetermined amount of radial and angular freedom relative to the further annular member for accommodating misalignment between the rotary and stationary assemblies.

Sinusoidal response of coaxial current shunts

Abstract: The coaxial shunt has been used to measure heavy surge current and continuous complex current for many years. However, shunt design has in general been inconsistent and unpredictable. For the design of an accurate coaxial current shunt, bandwidth and current carrying capability are the essential criteria to be established. This paper extends the previous work of Park, and others, by showing how the sinusoidal response of an uncompensated coaxial shunt can be more accurately predicted and verified in practice. A rigorous analysis is conducted on a coaxial shunt with axial potential connections in its uncompensated form. The analysis is free from any constraints of thin tubes (up to an overall limit on physical dimensions set in the text) and contains no unjustified mathematical simplifications which would otherwise detract from the accuracy of the final results. Skin-effect performance is evaluated by the development of a shunt design equation involving shunt dimensions and material properties following from what is considered to be a unique solution of Bessels equation of zero order. This equation is solved by the use of numerical computational methods containing original subroutines. Computer predictions of coaxial shunt design are included to show the use of the method in the design of shunts having bandwidths of between 0 Hz and up to 5 MHz. Practical tests show that coaxial shunts can be produced whose performances correlate with computer-predicted design to the accuracy classification 2.5 (0.025 per unit) of BS89 (1970). Individual shunt designs maintain their performance characteristics when subjected to continuous currents of up to 500 A r.m.s. at rated frequency while shunt dissipation is kept within that laid down in BS159 (1957). The results show that coaxial shunt design can be easily applied. Shunts based on this design technique are presently used in the measurement of complex currents in power-engineering applications, particularly those to be found in thyristor power conversion circuits.

Predetermination of current and torque requirements of an induction-motor-driven steel-bar rolling mill

Abstract: A mathematical model is developed for a complete open-train steel-bar rolling-mill drive. It is used in the prediction of the current and torque requirements of the induction-motor drive, and it takes account of nonlinearities in the motor and mechanical coupling. The method of determining the mechanical parameters and the calculation of roll torque of plastic-rigid materials is summarised. The validity of the model is checked by comparing results of a computer study with results taken from full-scale tests on a multistand rolling mill. Results showing the conditions that arise following the application of steel billets to the mill are presented.

Viscous shear fluid couplings

Abstract: The disclosure illustrates a viscous shear fluid fan drive comprising a driving disc received within an annular chamber of an output member. The disc and the chamber include closely spaced radially extending surfaces which transmit torque through a viscous fluid maintained between them. Pumping grooves are provided in the disc to insure rapid build up of hydrodynamic lubrication upon startup of the coupling. Cavities may be provided in the walls of the chamber to receive additional viscous fluid and extend service life of the coupling.

Where the buck should stop

Abstract: Last month, John Thompson and John Forge examined some of the oft‐quoted shortcomings of British management and concluded that too much senior executive time was devoted to issues which have traditionally been the responsibility of middle‐managers. Here, they set out to identify further causes of mis‐spent time and the repercussions that are likely to follow if influence and authority are not re‐delineated from shopfloor to boardroom.