Sample J72 from "Independent Research" Mellon Institute Annual Report 1960. Pittsburgh: Mellon Institute, 1961. Pp. 10-13. A part of the XML version of the Brown Corpus2,076 words 15 symbols 12 formulasJ72

CopyrightMellon Institute. Used by permission. 0010-2130

"Independent Research" Mellon Institute Annual Report 1960. Pittsburgh: Mellon Institute, 1961. Pp. 10-13.

Arbitrary Hyphen: high-voltage [0420]

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Two metabolites ( 1 , and 2 ) ) of p-aminobenzoic acid ( PABA ) which act as cofactors for the hydroxylation of aniline by acid-fast bacteria are biosynthesized from Aj . The 7 carbons of PABA are incorporated directly into metabolite 2 ( ( as shown with both ring-labeled and carboxy-labeled Af ) . Thirty-five of the 36 carbon atoms arise from Aj . All 28 carbons of metabolite 1 ( ( a product of mild acid hydrolysis of 2 ) arise from Aj . Metabolite 1 , isolated from the medium , however , showed a lower specific activity , which indicates endogenous synthesis of this metabolite .

Vigorous acid hydrolysis of metabolite 1 , destroyed the biological activity of the compound and liberated two aryl amines . Fragment A has been obtained in crystalline form as a dioxalate salt and free base . Preliminary evidence tentatively indicates that the molecule ( metabolite 1 ) ) is cleaved at a secondary amide bond . ( N. H. Sloane ; ; chemical studies are being pursued with the cooperation of K.G. Untch . ) studies on esterases -- Research on esterases in mammalian sera was continued . One of the most interesting findings was the extreme sensitivity of plasma arylesterases to rare earth ions . The inhibition of the enzyme by very low concentrations of lanthanum ion is probably the strongest known biological effect of rare earth salts . Various metal ions have been found to protect plasma arylesterase against inactivation by urea and guanidine . The effects can be related to the structure of this enzyme . The non-identity of serum and red blood cell arylesterase was also established . Furthermore , the hydrolysis of paraoxon was studied in mammalian sera , and it was found that it is hydrolyzed by albumin ( or a factor attached to it ) in addition to arylesterase . Selective inhibitors can distinguish the two activities . Investigations on the acceleration of human plasma cholinesterase were carried further . ( E. G. Erdos , L. E. Boggs , C. D. Mackey ) biophysical studies on modified fibrous proteins -- Electron-microscopical and physical-chemical methods were used to demonstrate the renaturation of heat-denatured collagen and ribonucleic acid . ( R. V. Rice )

A method was devised for extracting and purifying soluble earthworm collagen ( EWC ) . It was observed that EWC macromolecules are the same diameter ( 15 a. ) but much longer ( up to several microns ) than vertebrate tropocollagen . This unusual collagen also was shown to undergo a reversible thermal phase transformation . ( R. V. Rice , M. D. Maser ) studies on peptides and peptidases -- This investigation involved several aspects . Substance Z , an active urinary peptide , was purified by extraction in organic solvents and repeated column chromatography ; ; high-voltage electrophoresis and paper chromatography were used in preliminary structural studies ; ; pharmacological effects in vitro on isolated surviving organs and in vivo on blood pressure were assayed ; ; special equipment required for registering respiration and for recording the contraction of smooth muscles under various conditions was developed by the Instruments Section ( Victor Jackman , W. C. Barnes , J. F. Reiss ) ; ; and enzymes which terminate the action of peptides such as bradykinin and perhaps Substance Z were studied . Experiments are in progress to develop ultraviolet spectrophotometric techniques for assaying these enzymes and for studying their sensitivity to metal ions . ( E. G. Erdos , C. D. Mackey , A. G. Renfrew , W. B. Severs , E. M. Sloane ) seed proteins -- In a physiochemical study of seed proteins , the globulins of the Brazil nut have been investigated . In addition to the known principal globulin , excelsin , three other ultracentrifugally distinct components have been observed . A water-soluble protein of quite low molecular weight ( ca. 10,000 ) has also been found in this system and partly characterized . ( E. F. Casassa , H. J. Notarius )

continuum mechanics and viscoelasticity theory of non-newtonian fluids -- On the basis of a differentiability assumption in function space , it is possible to prove that , for materials having the property that the stress is given by a functional of the history of the deformation gradients , the classical theory of infinitesimal viscoelasticity is valid when the deformation has been infinitesimal for all times in the past . By strengthening the differentiability assumption , it has been possible to derive second and higher order theories of viscoelasticity . In the second-order theory , one of the normal stress differences can be calculated from the first-order stress relaxation function . ( B. D. Coleman with Walter Noll , Department of Mathematics , Carnegie Institute of Technology ) viscoelastic measurements -- An extensive series of measurements was made on a high-density polyethylene in a torsion pendulum instrument using forced sinusoidal oscillation , free vibration , and creep measurements over the temperature range of Af to 80-degrees-C . As many as seven decades of the time scale were thus covered isothermally . The simple time-temperature equivalence valid for many amorphous systems did not hold here . It was possible , however , to decompose the compliance into a sum of a frequency-independent component and two viscoelastic mechanisms , each compatible with the Boltzmann superposition principle and with a consistent set of time-temperature equivalence factors . ( Hershel Markovitz , D.J. Plazek , Haruo Nakayasu )

geochemistry trace elements in tektites , meteorites , and related materials -- The results of microanalysis of tektites ( natural glasses of unknown origin ) for gallium and germanium have shown that these glasses are probably produced from terrestrial ( or less likely from lunar ) matter by impact of a celestial body . The gallium / germanium ratio is higher than that for ordinary igneous , metamorphic , or sedimentary matter as a result of selective volatilization of the components of the tektite . Gallium oxide is less volatile than silica ( the main constituent of tektites ) and germanium oxide is more volatile . Australites ( tektites from Australia ) give the appearance of a second melting . In conformity with this conclusion a higher trace gallium content was found in the portion ( flange ) that has undergone a second melting . The silicate fractions of stony meteorites show gallium / germanium ratios similar to those of tektites because they too have undergone melting at some point in their histories .

Libyan Desert silica-glass , another natural glass , is composed of nearly pure silica and has the same trace germanium content as sands in the area . The gallium content , however , has been enhanced five-fold . This glass is probably formed from Libyan Desert sands by comet or stony-meteorite impact .

Nickel-iron meteorites with sufficient kinetic energy to produce large terrestrial explosion craters may nevertheless melt only small quantities of material . Most of the impact energy is spent in crushing and fragmentation . When rapid quenching follows melting , impact glasses may result . These always contain metallic inclusions . Impact glasses not containing elemental nickel-iron may have been produced by stony meteorites or comets . No meteorites have ever been recovered from paleoexplosion craters , and recent craters containing impact glass have all been produced by metallic meteorites with the exception of Aouelloul crater , Adrar , Western Sahara Desert . This crater contains impact glass with no metallic inclusions and no meteoritic material has been recovered . ( A. J. Cohen , John Anania )

inorganic chemistry Preparation of a coordination compound is often accomplished by the simple method of reacting a metal salt with a ligand in a suitable solvent such as an alcohol . By applying this general principle , a great number of complex compounds of osmium , ruthenium , iridium , and rhenium , with triphenylphosphine , triphenylarsine , and triphenylstibine have been obtained in this laboratory during the past few years . ( Lauri Vaska , E. M. Sloane , J. W. DiLuzio ) In the absence of direct evidence to the contrary , decomposition of solvent alcohol and coordination of its fragments to the metal were not considered , following the above heretofore-accepted assumption in preparative coordination chemistry . Recent work with radiocarbon and deuterated alcohols as solvents , however , has given evidence that metal-hydrido and carbonyl complexes may be readily formed by reaction with alcohol in some of these systems . Some of the previously reported compounds have thus been reformulated and a series of new hydrido and carbonyl compounds discovered , the more representative examples being Af , Af , Af , Af and Af ( Af ) .

The coordination complexes formed by transition metals with primary and secondary phosphines and arsines are being investigated ( R. G. Hayter ) . Particular interest is directed towards the condensation of these ligands with metal halides to form substituted phosphide or arside complexes . During the past year , these ligands have yielded some unusual five-coordinate complexes of nickel ( 2 ) and some interesting binuclear phosphorus-bridged complexes of palladium ( 2 ) ( see figure ) , as well as new compounds of the well-known type Af . The structures , properties , and reactions of these compounds are being studied .

In another study chromium-substituted aluminum oxyhydroxides and related species , prepared homogeneously by high-temperature hydrolysis , are being characterized and investigated spectrally in the ultraviolet region with a view to identification and semiquantitative estimation of the phases formed under varying preparative conditions . ( J. A. Laswick , N. L. Heatwole )

structure and properties of macromolecules elasticity of macromolecular networks -- The theory of elasticity of Gaussian networks has been developed on a more general basis and the equations of state relating variables of pressure , volume , temperature , stress and strain have been precisely formulated . Simple elongation has been treated in detail . The various stress-temperature coefficients for constancy of volume and strain , constancy of pressure and strain , and constancy of pressure and length have been interrelated . The dilation accompanying elongation and the simultaneously developed anisotropy of compressibility have been related to the elongation . In continuation of these theoretical studies , a more precise elucidation of the effects of imperfections in network structure is sought . ( P. J. Flory , C. A. J. Hoeve ) chain conformations of polymeric chains -- Recent theoretical work to calculate the dimensions of polymeric chains by Volkenstein and Lifson has been extended to include more general types of chains . The mean-square end-to-end distance of the polyisobutylene chain has been calculated in reasonable agreement with values deduced from viscosity data . These studies are being extended to different polymers to increase our knowledge about the hindrances to rotation around chain bonds . ( C. A. J. Hoeve , A. A. Blumberg ) crystallization in polymers and copolymers -- The crystallization of copolymers comprising Af units interspersed with a minor percentage of Af is limited by the inability of the crystal lattice characteristic of the former to accommodate the bulky side group of the latter . Only uninterrupted sequences of the former are eligible for formation of crystallites . Limitations on the lengths of these sequences diminish the stability of the comparatively short crystallites which can be formed , and this is reflected in a broadening of the melting range . ( Robert Chiang , J. B. Jackson , P. J. Flory ) Carefully executed melting studies on this system ( M. J. Richardson ) permit quantitative estimation of the instability engendered by reduced crystallite length . The complex morphology of polycrystalline homopolymers is necessarily dependent on the same factor . Hence , the present studies offer a possible basis for interpretations in the latter field . Contraction of muscle -- Glycerinated muscle , in the presence of the physiological agent ( ATP ) responsible for delivering energy to the mechanochemically active proteins of muscle , has been shown to undergo a contraction which is highly sensitive both to temperature and to solvent composition in mixtures of alcohols and water . Experiments carried out over long periods of time in order to allow establishment of a steady state have shown that the onset of contraction and its completion are confined to an interval of several degrees Centigrade and to a concentration range of only several per cent . The contraction therefore partakes of the character of a phase transition . While ATP appears to be necessary for the occurrence of contraction , its presence and enzymatic hydrolysis of it by the muscle protein myosin are not the only criteria for contraction . ( C. A. J. Hoeve , P. J. Flory ) anionic Polymerization -- One of the principal aims of anionic polymerization techniques is the synthesis of polymers of extremely narrow molecular weight distribution . A simple process for the preparation of nearly monodisperse polystyrene of predictable molecular weight has been developed . The preparation of such products is not new , but the systems heretofore employed in polymerizations have commanded considerable experimental skill and starting materials of a high purity . In the new process impurities present in the solvent ( benzene ) , the monomer , and in the reaction system which would cause deactivation of propagation centers , are rendered inactive prior to polymerization by gradual addition of initiator , a mixture of butyl-lithium and telomeric styryl-lithium , at a temperature low enough to suppress chain growth . Upon completion of the purging step , additional initiator appropriate for the molecular weight of the sample desired is added , and the system is then warmed to the polymerization temperature , at which the reaction is allowed to go to completion . The predictability of the molecular weights was found to be within 10% for the polymers prepared , with Af ratios less than 1.1 .

Contrary to observations with ethers , no apparent change of the reactivity of the chain ends takes place over considerable periods of time in benzene as solvent .