No abstract

A purification method for a-mannosidase from the seeds of Phaseolus vulgaris is described. The main steps are ammonium sulfate precipitation, DEAE-Sephadex ion-exchange chromatography , G-200 gel filtration, and isoelectric focusing. Two enzymes, a-mannosidase I and 11, with isoleectric points of 5.1 and 6.1 respectively, were found. Most of the a-mannosidase activity was present as a-mannosidase I. This enzyme has been extensively purified. According to the criteria of disc electrophoresis and sedimentation equilibrium , the final enzyme preparation was pure. a-Mannosidase I has a sedimentation coefficient of 11.2 S, and molecular weight of 194000. The enzyme activity was shown to depend on zinc. The pH optimum and Km value have been determined with p-nitrophenyl-aD -mannoside as substrate. a-Mannosidase I1 was only partially purified and some of its properties were studied in order to compare the two enzymes. a-Mannosidase, widely distributed in animal tissue , microorganisms , and plants, is abundantly present in the seeds of Phaseolus vulgaris [ l ] and Jack beans [2]. The enzyme has been partially purified from Phaseolus vulgaris [l] and more extensively from Jack bean meal [3]. The effect of the enzyme on mannoside bonds has been studied with different oligosaccharides, polysaccharides, and glyco-proteins [3]. So far, there have been no reports on the molecular characteristics. The present paper describes the extensive purification of the enzyme from Phaseolus vulgaris, and the determination of some of its physical properties.

The apparent admittance of a cylindrical antenna depends critically on the structure of the conductors near the junction of the antenna and the feeding line. For thin cylinders and closely spaced lines an ideal admittance can be defined in the hypothetical limit of "zero" line spacing. The approximate theoretical equivalent is the admittance seen by a delta-function generator with the infinite susceptance of the knife-edge capacitance subtracted.The iterated theoretical admittance of a cylindrical antenna with a delta-function generator is examin':d for from one to 30 iterations. It is shown that for fJ0a EO 0.1 or a/>.. .E; 0.016 (where a is the radms, fJo = 21T/ >.. the wave number) the conductance converges rapidly, but the susceptance increases continually with the added iterations by an amount proportional to the circumference of the ante!l~a-The m~re _accurat~ the s?lution, the nearer t~e susceptance appro~ches infinity. A simple empmcal correctiOn IS combmed With the second-order Iterated value to provide a good approximation of the ideal independent susceptance of the antenna. When f30 a EO 0.1, the second-order corrected admittance is essentially the same when calculated with either the exact kernel for the tubular antenna or the commonly used average kernel.Tables of the admittance Y, impedance Z, radian effective length fJohe, and directivity D are given.When combined with the terminal-zone network for a particular transmission line, the measurable apparent admittance and impedance of a cylindrical antenna are obtained with essentially as great an accuracy as is possible in terms of an "independent" admittance for the antenna. More accurate values depend on the individual analysis of each transmission-line-antenna configuration.

If the admi tta nce of a missi le, satellite, or drone-a ircraft antenna is mo ni tored a s the ve hi cle t ra vers es a n io n ized reg ion , it is possible to de te rmine t he free elect ron de ns ity and t he collision frequ ency of the region if theoretical re la t ions bet wee n t hese qua nt it ies are available. In t his pape r formu las a re developed that relate t he ad mittan ce of a n e lectricall y s hort cente r-driven d ipole or a base-dri ve n monopole when imm ersed in a cond ucting d ielect ri c to the e ffect iv e di electri c co nstant a nd conductivi ty of t he medium. F ro m wejl-known formulas re latin g these qu a nt ities to the free r lectro n density a nd the co ll ision frequ e ncy of an ion ized r egion, t hese latter ma y be d etermin ed d irectly fro m m easured ad mi ttances. The results obtain ed wh e n Lhe an tenna is t reated as a lumped capacito r a rc cons idered. It is shown t hat wh cn Lhe co ndu ctivity o f the mcd ium is in creased to a value t hat is st ill q ui t e sma ll, t he c ffect of radi a tio n on t he inpu t adm ittance becomes negli gible. The e lcct rica ll y s hort anLenna imlll ersed i n sea wate r is discussed brie Ry.

The in-situ stress contrast between a reservoir rock and the surrounding formations is important to the design and analysis of hydraulic fracture treatments. The stress contrast between layers controls the fracture's vertical (height) growth, which in turn affects the fracture length and width. As part of the Gas Research Inst. 's (GRI's) Comprehensive Study Well (CSW) program in the Devonian shales of the Appalachian basin, we measured in-situ stresses directly and used these values to calibrate acoustic log measurements to develop stress profiles across the Devonian shales. This discusses the measurement and interpretation of in-situ stresses, the use of acoustic logs to determine mechanical properties and a more complete stress profile, and the practical use of the stress profile in fracture-treatment design and analysis.In-situ stresses were measured directly throughout the Devonian shale interval with both openhole and cased-hole stress tests, conducted with nitrogen, a specially designed downhole shut-in tool, and a downhole quartz pressure gauge with surface readout. The paper describes the procedure used and presents interpreted stress-test results from two CSW's. Full-waveform acoustic tools were run to define elastic properties of the Devonian shales. These properties also were determined under both static and dynamic conditions from whole-core plugs taken in the shales. Logs were calibrated to core-measured values, and then elastic properties determined from the logs were used to compute an in-situ-stress profile, which was calibrated against field measurements of in-situ stresses. Finally, we discuss how these data are used to design and analyze hydraulic fracture treatments in CSW's.