摘要:

AbstractPresent‐day chemical and physical studies of the nucleic acid system of bacteria frequently call for quantities of cells which are beyond the capacity of traditional culture methods such as that of the shake flask. The case is therefore argued for an increased use of stirred deep cultures because a greater rate of output, at a higher cell concentration and with improved control of cultural conditions can be achieved. For the isolation of deoxyribonucleic acid and transfer ribonucleic acid, low growth‐rate cells should be the most prolific source: whereas for ribosomes, ribosomal ribonucleic acid and messenger ribonucleic acid, high growth cells should give bigger yields. It is concluded that the information is somewhat obscure on what are the best growth conditions for the production of the related‐enzymes.A batch method for producing low growth‐rate cells ofEscherichia coli, in lots of 1 kg dry wt., is then described, followed by a continuous method for producing high growth‐rate cells, with an output of 3 kg of dry cells per day. Both cultures have been designed to give maximum yield of cells by promoting maximum assimilation of the carbon substrate. From the point of view of designing a culture, the section dealing with the continuous process discusses the rationale of medium formulation, the calculation of aeration requirements and briefly reviews earlier work on the kinetics of continuou

ISSN:0021-8871    

DOI:10.1002/jctb.5010180601

出版商:John Wiley&Sons, Ltd    

年代:1968

数据来源: WILEY

摘要:

AbstractIsobaric vapour‐liquid equilibrium data have been determined for the binary systems hexane‐hexylalcohol and heptane‐hexylalcohol at 760 mm of Hg total pressure, using a Scatchard and Ticknor still. The isobaric vapour‐liquid equilibria of both the systems have been correlated satisfactorily by the equations of Redlich&Kister as modified by Chao despite the wide variation in boiling points.Ewellet al.1have classified liquids into five groupings based on their properties of forming hydrogen bonds. According to this classification, hydrocarbon‐alcohol combinations involve breaking of hydrogen bonds and always show positive deviations. A systematic study of the vapour‐liquid equilibrium data of these has been attempted and the present work presents

ISSN:0021-8871    

DOI:10.1002/jctb.5010180602

出版商:John Wiley&Sons, Ltd    

年代:1968

数据来源: WILEY

摘要:

AbstractConcentrated solutions of casein (5·5–6·0%), modified by the addition of formaldehyde, undergo rapid gelation in the presence of sodium metasilicate and sodium hexyl sulphate. This gelation occurs more readily when a mixture of both is used. The presence of an extremely small amount of either of the reagents with the other decreases the time of gelation considerably. The role of different constituents of the gelation mixture is discussed. The use of sodium metasilicate containing small amounts of sodium hexyl sulphate to replace sodium aluminate in the manufacture of casein fibres is sugges

ISSN:0021-8871    

DOI:10.1002/jctb.5010180603

出版商:John Wiley&Sons, Ltd    

年代:1968

数据来源: WILEY

摘要:

AbstractThe specification of a graphite suitable for DRAGON fuel tubes which operate on the ‘back‐sweep’ purge principle includes the two requirements: (i) the viscous permeability constantB0<3 × 10−11cm2, and (ii) the fission‐gas transmission coefficientD'<1 × 10−6cm2/sec at 20 atm., 7500, and 2 psi pressure drop. Calculations, based on the results of a study of the counter‐diffusion of gases in graphite, suggested that, providing the first criterion was satisfied, the second requirement would be met by a material whose pores were on the average at least 5·5 μm in diameter.A series of experimental graphites based on grists of scrap nuclear‐grade graphite was made with the object of producing artefacts whose pore sizes were in the region of 10 μm, without exceeding the specified limit on permeability. After several adjustments to the size distribution of the grist, one was obtained which yielded an artefact which, after subsequent pitch impregnation, satisfied the reactor specification. The family of graphites based on this particular grist is known as HX30. A second series of experiments demonstrated that this material could be made in full‐sized rods 8 ft long by 3·25 in. dia. Any of four baking routes was possible, depending on whether the primary bake and the re‐bake after impregnation were carried out under atmospheric pressure or at 100 psig. An appropriate number (1 to 3) of impregnations yielded an acceptable graphite.The superior properties of HX30 are considered to be due chiefly to the exclusion of fines (below 300 BSS mesh) from the grist but the nature of the grist (graphite and not coke) and the use of re‐extrusion are probably also significant. The original theoretical approach appeared to be largely vindicated by the pore‐size distribut

ISSN:0021-8871    

DOI:10.1002/jctb.5010180604

出版商:John Wiley&Sons, Ltd    

年代:1968

数据来源: WILEY

摘要:

AbstractThe application of a laboratory scale rotating helix crystalliser to the separation of a number of organic and aqueous systems is described. The results show separations equivalent to several stages with systems exhibiting the phenomenon of solid solution and the recovery of components in high purity from multi‐eutcetic system

ISSN:0021-8871    

DOI:10.1002/jctb.5010180605

出版商:John Wiley&Sons, Ltd    

年代:1968

数据来源: WILEY

摘要:

AbstractThe preparation of novel compounds containing the quaternary ammonium group is described. These compounds have been tested as promoters of filmwise condensation.

ISSN:0021-8871    

DOI:10.1002/jctb.5010180606

出版商:John Wiley&Sons, Ltd    

年代:1968

数据来源: WILEY

ISSN:0021-8871    

DOI:10.1002/jctb.5010180607

出版商:John Wiley&Sons, Ltd    

年代:1968

数据来源: WILEY