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The purpose of this paper is to present a metod to calculate real molecular weight averages of polymer samples from GPC chromatograms where the instrumental spreading functions are skewed and the concentration effect exists. In this method, it is assumed that (1) the skewed chromatograms of monodisperse polymer samples can be represented as resultant of halves of two different Gaussians, (2) the resolution factors are regarded as constant in the case of low sample loading, and (3) the peak elution volume is independent of the presence of other components in the case of low sample loading. Adequate monodisperse polystyrenes and the mixtures (binary, seven and ten components) were examined for this purpose; and the molecular weight averages calculated by this method were compared with the ones obtained by Rosen and Provder's method. From the results in our study, it is found that this method can be available for correcting molecular weight from GPC chromatograms except for very narrow high molecular weight samples.

Compacted mixtures of UO 2 and MgO with Mg U ratios up to 0·07 readily form solid solutions when heated at 1600° in a slightly oxidizing atmosphere such as a 5% H 2 -95% CO 2 mixture. No oxygen vacancies are associated with these solid solutions which can always be represented as U x Mg 1− x O 2+ z where z cannot be negative. The reduction of these solid solutions has been studied. The amount of magnesium remaining in solution depends not only on the oxygen potential of the reducing gas but also on the concentration of dissolved magnesium prior to reduction. This concentration effect is most marked at the higher concentrations of dissolved magnesia. It is shown that the quantity of magnesia which can be dissolved in UO 2 at a given oxygen potential is less than the quantity retained in solution when a solid solution, prepared in a more oxidizing atmosphere, is reduced at that oxygen potential. Magnesia precipitates from solution during reduction in the form of small clusters which are distributed both inter- and intra-granularly in the compacts.

Phosphate uptake by monolayers of 3T3 cell decreases when the cultures enter the stationary phase, even when incubated in fresh medium containing 10% serum. However, SV 3T3 cultures retain a high rate of phosphate uptake when the cells reach saturation densities. We have observed that 3T3 cells grown to stationary phase in monolayers and then trypsinized and incubated in suspension, display an increase in phosphate uptake when the cell concentration is decreased from 10 6 cells/ml to 10 5 cells/ml. Where the cell concentration is further reduced from 10 5 cells/ml to 2.5 × 10 4 cells/ml there is no further increase in the rate of phosphate uptake. We observed, on the contrary, a small decrease. The “concentration effect” (the decrease of phosphate uptake when the cell concentration increases from 10 5 to 10 6 cells/ml) is larger when cells originate from a culture in stationary phase than when they originate from a culture in log phase. The “concentration effect” may be observed 10 min after cell incubation but is larger after a lag time of 40 min incubation. Differences in the “concentration effect” may be noted between 3T3 and SV 3T3 cells. In SV 3T3 cells no significant variations of phosphate uptake were observed when the cell concentration was changed. Thus, differences between phosphate uptake in 3T3 and SV 3T3 cells are large when cells are incubated at high concentrations or at high densities and small when they are incubated at low concentrations or at low densities. The “concentration effect” in 3T3 cells supports the assumption that interactions between cells cause the decrease of phosphate metabolism in dense culture. Diffusion of an inhibitor into the medium remains the more plausible explanation of the data.

Laboratory grown cultures of the green alga Pediastrum boryanum (Turp.) Meneg. concentrate mercury in amounts greater than the concentration in the culture medium. The concentration effect proceeds rapidly during colony formation and is directly dependent upon the materials of the outer layer of the cell wall known to include silica and sporopollenin. The alga displays exceptional tolerance to the rather high levels of mercury used. 13 references, 4 figures.

Reaction kinetics in the presence of micelles is formulated on the basis of a microheterogeneous reaction in accordance with a current model of micellar catalysis. The necessary molecular parameters are the radius of the hydrocarbon core of a spherical micelle, the thickness of a reaction surface layer, the surface and zeta potentials, and a distribution coefficient of a hydrophobic substrate. The derived expression was applied to the hydrolysis reaction of methylorthobenzoate in the presence of sodium dodecylsufate micelle to describe reaction properties such as a rate-surfactant concentration profile, inhibition by added electrolyte, and activation energy. The micellar effect on the reaction rate was explained by a simple concentration effect of the reactants; the stabilization of the transition state by the micellar surface potential need not be taken into consideration. Inhibition of the orthoester hydrolysis by a cationic surfactant is also predicted.

Minced rat pancreas retained a large portion of estradiol (E2) after incubation with either 5 nM or 1 μM concentrations of radioactive E2. The mince was homogenized in low salt buffer and separated into nuclei, mitochondria, microsomes, and cytosol by centrifugations at 1000 g, 10,000 g, and 105,000 g, respectively. The three pellets were washed 3 times prior to extraction with 0.4 M KCl buffer. The minced tissue took up about 77% of the labeled E2 irrespective of the initial concentration of E2 in the incubation medium. The largest amount of radioactivity was retained by the microsomes; and no more than half of this radioactivity could be extracted with 0.4 M KCl. The distribution among the fractions was the same for incubations in 5 nM and 1 μM E2. The ratio of E2 to protein in the cytosol, and in the nuclear, mitochondrial, and microsomal extracts was of the order of magnitude of pgE2/mg protein for incubations in 5 nM E2, and of the order of magnitude of ngE2/mg protein for incubations in 1 μM E2, with the highest ratio in the microsomal extract. Similarly, percentage binding is not reduced by incubations in a 200-fold higher concentration of E2. Binding was significant in all three extracts or cytosol. The sucrose density gradient gave higher results for binding than the assay by a Sephadex G-25 column. Per cent bound was more than 50% in all fractions as measured by sucrose density gradient, with the cytosol showing 90% binding. The bound radioactivity in cytosol and in the three extracts sedimented in the 4s region. The experiments show that rat pancreatic tissue has a high capacity to bind estrogens. Binding curves with E2 or estriol (E3) were obtained with either human or dog pancreatic cytosol by equilibrium dialysis or DCC. These curves showed that the cytosol has a low capacity with an apparent association constant of 107 to 109 M−1 for E2 and E3 and a high capacity of low association, especially for E2. A protein concentration effect was noted for the binding of E2 or E3 by human cytosol. Whereas only one peak in the 4s region was detected by sucrose density gradient, 2 or 3 peaks were obtained by chromatography of human or dog cytosol on Sephadex G-100. These results point to the possible presence of more than one E3 binding in the pancreatic cytosol.

A numerical model was constructed to simulate the scavenging of hygroscopic aerosols with the aim of studying the influence of several meteorological parameters on the composition of rainwater and the atmospheric aerosol content. The scavenging mechanism is found to be highly dependent on (1) the relative humidity RH, especially in relation to its effect on the size distribution of hygroscopic particles (for non-hygroscopic particles the concentration effect during scavenging for low relative humidity is not so pronounced because the scavenging coefficients decrease as the impurities in the raindrops are being concentrated due to evaporation; e.g., for a rainfall intensity of 1.2 mm/h, 0.5-mm rainfall, and non-hygroscopic particles, the average rainwater concentration for RH = 50% is only 1.2 times larger than that for RH = 94%), (2) the rainfall intensity (or more fundamentally the raindrop size spectra), especially for small rainfalls, and (3) the chemical nature of the particles. With the assumption of no particle replenishment, only 20% of the initial aerosol mass remained in the subcloud layer after 4-mm rainfall for the best scavenging conditions and after 15-mm rainfall for the worst conditions. Therefore after these rainfalls, changes in the rainfall intensity and relative humidity would have little effect on the average rainwater concentration, since little aerosol mass remains to be scavenged. The model predictions of average rainwater concentration variations due to meteorological parameter changes are consistent with values actually measured.

Pre-mixing oxygen with the fuel of diffusion flames markedly increases the level of soot formation, the effect being most pronounced with unsaturated and aromatic hydrocarbons and least with saturated ones. With ethylene, almost five times as much soot is obtained when 10% of the stoichiometric oxygen requirements of the flame is added to the fuel. Larger amounts completely suppress soot emission. The experimental evidence suggests that the role of the oxygen at low concentrations is to promote polymerization of the fuel to high-molecular-weight soot precursors, rather than a thermal effect. After 10 to 15% of the stoichiometric oxygen requirements have been pre-mixed with the fuel, carbon emission is abruptly eliminated over a narrow range of oxygen concentrations. This must be brought about by an oxidation of the fuel or of the potential carbon-forming intermediate which predominates at the higher oxygen concentrations. Dilution of the oxygen with inert gases such as nitrogen, argon and helium reduces its effectiveness to promote the formation of carbon, and appears to be a concentration effect, a conclusion in full agreement with the well known observation that higher pressures lead to increased soot formation. Other free-radical generators such as nitropropane and amyl nitrite also promote soot formation.

The influence of solute concentration on measurements of the viscosity and sedimentation properties of DNA solutions is very great. Enough data has been accumulated in recent years, however, to permit a quantitative description of these concentration effects for DNA samples of molecular weight below roughly 16·106. It has therefore become possible to measure [η] and s0 (and indirectly molecular weight) for such samples from single measurements on generally available equipment. Above molecular weight 16·106 the possibility of such a simplification is at present excluded by the magnitude of the concentration effect in sedimentation and the gradient effect in viscosity, plus the newly studied phenomenon of speed dependence in sedimentation. It is shown, however, that rotor speed does not influence the sedimentation of samples up to molecular weight 16·106 until a critical high velocity is reached.

The production of ethane accompanying the thermal decomposition of ethylene on bare and hydrogen covered (110), (100), (112) and (111) tungsten surfaces has been studied. The fraction of ethylene converted to ethane is found to vary from face to face, but in no case does the amount of ethane produced correspond to hydrogenation of more than 1.5% of the chemisorbed ethylene; the remainder decomposes to a carbon residue and gaseous hydrogen. With no preadsorbed hydrogen (i.e., self-hydrogenation) the order of activity, as given by the fraction of ethylene converted to ethane, is as follows: (110) < (100) ~ (112) < (111). With preadsorbed hydrogen (hydrogenation) the order of activity is approximately the same. (110 < (100) < (111) < (112). The inversion in the order for the (112) and (111) planes is due to a concentration effect. The increase in the fraction of ethylene hydrogenated over the fraction self-hydrogenated increases as the ratio of chemisorbed hydrogen to chemisorbed ethylene increases, and in the case of the (112) plane this ratio is a factor of 7 larger than the same ratio for the (111) plane. When D2 is substituted for H2 in the hydrogen predose, the extent of incorporation of D atoms in the ethane product, as indicated by the amount of d5- and d5-ethane relative to d2-ethane, is ordered approximately in the inverse of the self-hydrogenation activity. The amount of ethane produced is shown to be inconsistent with a Rideal-Eley mechanism, but consistent with the Horiuti-Polyani or half-hydrogenated state mechanism. The crystallographic dependence for hydrogenation and deuteration is a consequence of the reverse of Eq. (1). The probability of this step occurring decreases with increasing metal-metal spacing. A high density of short spacings as on the (110) plane would yield the observed small amounts of ethane but extensive incorporation of D atoms, while a high density of long spacings as on the (111) plane would yield the observed larger amounts of ethane with less extensive incorporation of D atoms.

By using the rheological equation obtained from the theory of network structure, the expressions of storage and loss moduli are obtained as functions of the chain length. The concentration dependence of storage and loss moduli is obtained theoretically in closed form by investigating the relation between chain length and concentration. The tendency of shift from the Zimm-like behavior to the Rouse-like is explained in terms of the concentration effect on the number of intermolecular junctions, whereas in Tschoegl's theory it is interpreted in terms of decreasing hydrodynamic effect. The principal results obtained are as follow. 1. The quantity J e C /(1- v 1 /η r ) 2 pass through a maximum and decreases inversely proportional to concentration in moderate concentrations and to the square of concentration in high concentrations. 2. The low shear viscosity is proportional to M 3.5 C 3.5 in moderate concentrations and to M 3.5 C 6 in high concentrations. 3. The storage modulus and the loss modulus transform f...

One of the fundamental problems in the chemistry and physics of macromolecular compounds is that of the resistance of polymers to the action of various physical and chemical agents. In the literature the thermal and thermal-oxidative degradation of polymers in the condensed phase (in bulk) have been examined in greatest detail [1–4]. The degradation of polymers in solution has not been studied sufficiently [5]. In the present work a study was made of the degradation of a polymer under mild conditions (at 95°) in solution at various concentrations, in order to ascertain the type of reaction between the macroradicals.

The S 1 (n, √ * ) ⇋ S 0 fluorescence and absorption spectra of 9, 10-diazaphenanthrene solutions in hydrocarbons possess at 77°K a quasilinear structure (Shpolskii effect). In the frozen n -hexane matrix ( c = 10 -4 M) the fluorescence spectrum displays a triplet structure (22 181, 22 169 and 22 149 cm -1 for the O-O transition). The spectra of 9, 10-diazaphenanthrene solution are shifted towards the red compared with those of the single crystal (∼ 900 cm -1 ). A good agreement between the calculated and experimental values of this shift is obtained. A strong concentration effect on the structure of the spectra is discussed. A quasilinear structure is observed also in the second absorption band.

Two internal friction peaks have been identified in vanadium. One occurring at 186°C for frequencies of 1 cps is associated with the stress-induced diffusion of oxygen, and the other occurring at 272°C is associated with the diffusion of nitrogen. The corresponding activation energies for these peaks were found to be 28.6 and 34.1 kcal, respectively. The skewness of the oxygen peak has been shown to be a concentration effect.

In order to determine the reactive state of acridine when it is photoreduced by ethanol, two types of experiments were undertaken. The first was to study the concentration effect of ethanol on the quantum yield in a benzene solution. These results, however, could not give any unequivocal answer. The second type of experiment was, therefore, made from the standpoint of the triplet energy transfer, using eosine as an energy acceptor for the photoreduction of acridine in an ethanol solution. It was found that, in a deaerated solution, the quantum yield of acridine photoreduction is not affected by the addition of eosine, whereas it was established by the flash technique that, under similar conditions, the energy transfer from the acridine triplet state to eosine occurs at approximately the diffusion-controlled rate. These results lead to the conclusion that the reactive state is not the lowest triplet state.

The concentration effect with sea waters containing more than the normal amount of potassium has been studied in Valonia macrophysa. This was done by comparing the initial changes in P.D. across the protoplasm when natural sea water bathing the cell was replaced by various isotonic dilutions of KCl-rich sea waters. With small dilutions of KCl-rich sea waters, the P.D.-time curves are of the same form as with the undiluted solution, exhibiting the fluctuations characteristic of KCl-rich solutions. This indicates that with these solutions K+ enters Valonia protoplasm and plays an important part in the P.D. The value of the initial rise in P.D. decreases with increasing dilution. With high dilutions of KCl-rich sea waters, the P.D.-time curves are of quite different shape, resembling the curves with diluted natural sea water; the P.D. is practically independent of small changes in the concentration of potassium, and increases with increasing dilution. That is, with these higher dilutions, the sign of the concentration effect is reversed, becoming the same as with diluted natural sea water. The greater the concentration of KCl in the undiluted sea water, the higher is the critical dilution at which K+ ceases to influence the P.D. For a wide range of sea waters containing both KCl and NaCl, it is shown that the concentration effect above the critical dilution is determined solely by the activity of NaCl in the external solution. It is concluded that with dilute natural sea water and with high dilutions of KCl-rich sea waters we have to do with a diffusion potential, involving only the Na+ and Cl- ions, which are diffusing out from the vacuole. A quantitative relation between the composition of the sea water and the critical dilution has been deduced from the classical theory of the diffusion of electrolytes. It is shown that with dilutions less than this critical value the diffusion of K+ in the outer non-aqueous layer of the protoplasm is directed inward; hence K+ enters the protoplasm from these solutions. With dilutions greater than the critical value, the diffusion of K+ in this layer is directed outward; hence K+ does not enter the protoplasm. Since the P.D. shows no evidence of this outward diffusion of K+, it is concluded that the amount of K+ ordinarily present in the protoplasm is too small to produce any lasting electrical effect, and that the outward diffusion of K+ from the vacuole is prevented by the mechanism responsible for the accumulation of KCl in the cell sap.

Effects of water stress and H-ion concentration on the rate of translocation of 14C-labeled photosynthates in Satsuma mandarin trees were studied.When the root growth was suppressed, translocation to the remaining plant parts (growing areas) was decreased and more 14C was accumulated in the leaves.In the plot of pH 3.0 a little decrease in the rate of translocation to fruits was observed, while in the plot of water stress the accumulation of 14C in the juice was heavily decreased.Water stress caused an increase in total sugar concentration of the juice. It seems likely that this was partly a result of the concentration effect arisen from water stress. However, in this case other factors such as polisacharide metabolism may also play an important role in the process of sugar accumulation in the juice.

NMR spectra of a number of 5-unsubstituted and 5-halogenopyrimidines were determined in solvents of varying acidity. The C-5-halogen atom causes downfield shift of the resonance peak for the methyl group attached to the C-6-position. Methoxy groups at the C-2- and C-4-positions are differentiated for 5-halogeno-2,4-dimethoxy-6-methylpyrimidine which can not be separated for 5-unsubstituted pyrimidines, and variation for their chemical shifts in acidic solvents are discussed. A certain amount of hydrogen bonding is suggested for 4-hydroxypyrimidines on the basis of the concentration effect for the NH resonance peak.

Summary The formation of gas hydrates in polyacrylamide gels was attempted using hydrate formers with different solubilities in water. Hydrate crystals of highly water-insoluble trichlorofluoromethane formed only at the gel-hydrate former interface. Hydrate crystals of highly water-soluble ethylene oxide formed abundantly within the gel, and the depth of penetration depended on the equilibration time prior to initiation of crystallization. Equilibration for 166 hrs resulted in the formation of ethylene oxide hydrate throughout a 5-cm column of gel. All ethylene oxide samples were observed to recrystallize following the initial crystallization process. Hydrate crystals of highly watersoluble sulfur dioxide and slightly soluble dichlorofluoromethane also formed within the gel. The sulfur dioxide hydrate crystals were present in quantities similar to those obtained with ethylene oxide, whereas the dichlorofluoromethane hydrate crystals were far less abundant. Several of the experiments were successfully repeated using an agar substrate. In the case of dichlorofluoromethane, the quantity of hydrate crystals in the gel was influenced by the method of formation. This was not true of ethylene oxide hydrate.

It has been shown that neither stopcock grease nor water in a Pyrex or soft‐glass vessel affect the concentration of hydrogen‐deuterium mixtures. Diffusion through palladium gives a concentration of the isotopes which is about that to be expected from an atomic diffusion process. Desorption from charcoal at liquid air temperatures gives the concentration effect to be expected from a diffusion as molecules. Mercury, Pyrex and soft‐glass surfaces at room temperature and charcoal at liquid air temperatures do not promote the reaction between hydrogen and deuterium. Chromium oxide and nickel‐kieselguhr surfaces promote the reaction between hydrogen and deuterium in the temperature range between — 190° and 110°C. A palladium surface catalyzes the reaction at 270°C. Experimental values have been obtained for the equilibrium constant of the reaction between hydrogen and deuterium from the temperature of liquid air upwards, in accord with theoretical calculations by Urey and Rittenberg based on statistical mechanics.

As the concentration of N,N-dimethylaminosuccinamic acid (DMASA) increases, the germination of kale seeds (Brassica oleracea L. var. acephala) treated with 100 mg of coumarin per liter is initially reduced and then increased. A curve of germination versus concentration of DMASA is parabola-like with a minimum at 10−3 − 5 × 10−3 M. Kinetin at 10−4 M and gibberellic acid at 10−4 M reduce and reverse the inhibition of germination caused by coumarin and the growth retardant. On the other hand, DMASA at 5 × 10−3 M, in spite of its slight inhibitory activity, reduces the toxic effect of kinetin applied in the supra-optimal concentration of 5 × 10−4 M. Indole-3-acetic acid increases the inhibitory effects of coumarin and DMASA.In the germinating seed of kale, DMASA possibly acts as the antagonist of gibberellin biosynthesis; coumarin possibly blocks an unknown metabolic pathway, controlled by kinetin.The paradoxical concentration effect of DMASA remains unexplained.

Anaesthesia was induced in two volunteers using 100% nitrous oxide and 92%, 87% and 80% nitrous oxide with oxygen, at atmospheric pressure; 50% nitrous oxide with oxygen at 2 atmospheres absolute (ATA); and 85% nitrous oxide with oxygen at 1.2, 1.4, 1.6 and 2 ATA. Measurements included: the duration of induction up to the subject's failure to respond to auditory stimuli (time to no response or TNR) and comparison of this with the time to a specific change observed in corresponding bifrontal electroencephalograms; pulmonary ventilation and net gas exchange, using a bag-in-box system; end-tidal concentration of nitrous oxide using an infra-red gas analyser; indirect systolic arterial pressure and e.c.g. Each subject presented characteristic patterns of ventilation, arterial pressure and pulse rate, but there were anomalies. Net uptake correlated less well than expected with the partial pressure of nitrous oxide administered, particularly with subject B for whom there was a very close correlation between TNR and time to a specific change in the e.e.g. Using different concentrations of nitrous oxide at about the same partial pressure, relative TNRs were consistent with the "concentration effect". Some clinical effects of short-term hyperbaric nitrous oxide are mentioned. Explanations for most of the anomalous results emerged from a mathematical model of the experiments which is described in Part II.

The photopolymerisation of n-propyl and n-butyl methacrylate to high conversions has been investigated, and the gel effect compared with that found for the methyl ester1. A kinetic analysis, based on a radical concentration effect caused by the occlusion of active centres, has been applied successfully to these reaction. Die Photopolymerisation von n-Propyl- und n-Butylmethacrylat wurde bei hohen Umsatzen untersucht und der Geleffekt mit demjenigen, den man fur den Methylester findet, verglichen1. Eine kinetische Analyse, die sich auf die Annahme eines Radikalkonzentrationseffektes durch den Einschlus aktiver Zentren stutzt, wurde mit Erfolg auf diese Reaktion angewendet.

In various ternary systems of the type polymer A – polymer B – solvent S, a dip or peak has been observed in the [η] – cB curve at the critical concentration of polymer B. ([η] is the intrinsic viscosity of A in mixed solvent consisting of B and S, and cB is the concentration of B in this mixed solvent.) It is shown that such a critical concentration effect is most likely to occur when the solvent is poor for polymer B, and will be the larger the poorer the solvent.Evidence is also presented in support of the hypothesis that if, as is usual, the two polymers repel each other, the effect is a dip if the solvent is good for polymer A and is a peak if the solvent is sufficiently poor for polymer A.Critical concentrations of polystyrene, polyvinyl acetate, and polymethyl methacrylate (five different samples) have been measured in this way in 12 different ternary systems. These observed critical concentrations are in good agreement with values calculated using the equation previously described, according to which the critical concentration of a polymer is inversely proportional to its intrinsic viscosity in the solution.

The hydrogenation of butadiene catalyzed by pentacyanocobaltate(II) was studied in water and in glycerol-methanol-water and ethylene glycol-methanol solutions. The amount of hydrogen absorbed, and the rate of hydrogen absorption, in the water solvent were much greater than in the other solvents. The composition of the butenes produced by the hydrogenation in the water solution was trans-2->>1->cis-2-butene at CN/Co >trans-2->cis-2-butene at CN/Co>5.1; this composition was affected by the concentration of the complex. The composition of the butenes produced in the glycerol-methanol solution was trans-2->>1–>cis-2-butene at CN/Co cis-2->>trans-2-butene at CN/Co>5.4; a concentration effect similar to that in the water solution was observed. The composition of butenes in the glycerol-methanol-water solution at CN/Co=6.0 was remarkably affected by the composition of the solvent. In the ethylene glycol-methanol solution, cis-2-butene was much more producible than in the glycerol-methanol ...

The concentration effect of the reactant gases, Ne, N2, Ar and Kr, admixed with the helium gas is studied in the injected-ion drift tube by comparing the mass spectra of the reservoir gas and of the gas sampled directly from the drift tube. It is found that the flow through the aperture of the drift tube, which has a diameter of 0.7 mm ∅, is “medium flow” in the present experimental pressure range(from 0.2 to 1.4 Torr), and that the concentration ratios vary with the pressure in the drift tube. The concentration ratios measured at 0.6 Torr which is most frequently used are 1.8, 2.15, 2.32 and 3.0 for the case of Ne, N2, Ar and Kr, respectively. These results are compared with the theory of the two component gas flow through an aperture. The correction of reaction cross sections previously measured by the injected-ion drift tube technique is described. The correction factor for the charge transfer cross section 22Ne++ 20Ne → 22Ne + 20Ne+ is found to be 0.89, and more satisfactory agreement with theory is obtained.

The delayed fluorescence observed in the mixed crystals of benzo(f)quinoline in biphenyl host has been found to be independent of temperature in the low-temperature region from 90°K down to liquid helium temperature, and subtraction of this temperature-independent contribution gave straight-line fits of the log IDF/IP2-vs-l/T plots over the whole temperature range studied. In addition, some remarks have been made on the concentration effect.

Values have been calculated for apparent mobilities and partition coefficients in the outer non-aqueous layer of the protoplasm of Nitella. Among the alkali metals (with the exception of cesium) the order of mobilities resembles that in water and the partition coefficients (except for cesium) follow the rule of Shedlovsky and Uhlig, according to which the partition coefficient increases with the ionic radius. Taking the mobility of the chloride ion as unity, we obtain the following: lithium 2.04, sodium 2.33, potassium 8.76, rubidium 8.76, cesium 1.72, ammonium 4.05, ½ magnesium 20.7, and ½ calcium 7.52. After exposure to guaiacol these values become: lithium 5.83, sodium 7.30, potassium 8.76, rubidium 8,76, cesium 3.38, ammonium 4.91, ½ magnesium 20.7, and ½ calcium 14.46. The partition coefficients of the chlorides are as follows, when that of potassium chloride is taken as unity: lithium 0.0133, sodium 0.0263, rubidium 1.0, cesium 0.0152, ammonium 0.0182, magnesium 0.0017, and calcium 0.02. These are raised by guaiacol to the following: lithium 0.149, sodium 0.426, rubidium 1.0, cesium 0.82, ammonium 0.935, magnesium 0.0263, and calcium 0.323 (that of potassium is not changed). The effect of guaiacol on the mobilities of the sodium and potassium ions resembles that seen in Halicystis but differs from that found in Valonia where guaiacol increases the mobility of the sodium ion but decreases that of the potassium ion.

By studying the relation between the concentration and the oxidation activity of various metal catalysts, mostly naphthenates, oleates, linoleates, and caprates of manganese, cobalt, and nickel salts, as well as mixed catalysts of two kinds, it has been established that, in general, there is an anomalous effect of the catalyst concentration-namely, the catalytic activity disappears above a certain point in the concentration of the catalyst. The anomalous concentration effect of a catalyst is observed in the oxidation of toluene and p-xylene with all the catalysts, but chromium naphthenate is a lone exception in the oxidation of p-xylene. It has been shown that the anomalous effect is due to the association of the catalyst in the hydrocarbon solvent to be oxidised, and that the associated catalyst does not act to promote oxidation. The association is reversible, being dependent on the concentration of the catalyst, so the anomalous concentration effect of a catalyst disappears on dilution.

In addition to the established effects of the nature of the foreign electrolyte on the current voltage curves in d.c. polarography, a pronounced dependence of the peak currents on the concentration of the foreign electrolyte is determined in square wave polarography. A marked effect is due to the structure of the double layer. This concentration effect is shown by examples for polarographically reversible and irreversible reductions. Results are of particular importance for applications of this method in microchemical and trace analysis work, since they show that a considerable increase in the sensitivity of indication of irreversible reactions is obtained without the indication of reversible reactions being impaired if, contrary to earlier recommendations, solutions of low foreign-electrolyte content are used. The charging current waves occurring at a high resistance of the cell circuit are described.

1. The stimulating efficiencies of some normal primary aliphatic alcohols have been determined for the barnacle, the frog, and Planaria, under conditions which do not involve narcosis or simultaneous stimulation by other agents. 2. Concentrations of the successive alcohols necessary to produce a given stimulatory effect vary according to the following geometrical series: 1: a–1: a–2: a–3: a–4: . . . ., where a represents some real number. 3. Within certain limits the relationship between the logarithm of the concentration necessary to produce a given effect and the reciprocal of the reaction time is linear in the frog and in Planaria. 4. The concentration effect may be expressed by an equation which contains one constant characteristic of the alcohol series, and another one characteristic of each member. The ratio of the latter constants for successive alcohols represents a in the above series. 5. The stimulation by alcohols in these animals is considered to be due to energy changes at the receptive surfaces, brought about by a definite orientation of the respective alcohol molecules. Increase in stimulating efficiency as the number of CH2 groups increase must be due to the rôle of the non-polar portion of the alcohol molecule, since the polar group remains practically constant throughout the series. 6. In homologous series of organic compounds it is conceived that stimulating effects will be produced either by the polar group or the non-polar group, according to which one becomes dominant in effect, or to a combination of the two.

The gas chromatographic solutions of polar substances in a non-polar stationary phase were studied. The semiempirical method of calculation of dispersion forces in such solutions is discussed. A comparison of gas chromatographic and static values of heats of solution shows that the concentration effect has great importance in the systems under study. The values of concentration effects were tabulated for the different chemical classes of substances.

A method distinguishing between the concentration effect due to the cell wall and that due to the protoplasm is described: the importance of this lies in the fact that if the protoplasm shows a concentration effect one or both ions of the salt must tend to enter its outer surface. Studies on the concentration effect of KCl with living protoplasm of Nitella show that when P.D. is plotted as ordinates and the logarithm of concentration as abscissæ the graph is not the straight line demanded in the ideal case by theory but has less slope and is somewhat concave to the axis of the abscissæ. With a variety of salts the dilute solution is positive, which indicates that the cation has a greater mobility in the protoplasm than the anion or that the partition coefficient of the cation (Ac) increases faster than that of the anion (Aa) as the concentration increases. If the result depended on the partition coefficients we should say that when Ac ÷ Aa increases with concentration the dilute solution is positive. When Ac ÷ Aa decreases as the concentration increases the dilute solution is negative. In either case the increase in concentration may be accompanied by an increase or by a decrease in the relative amount of salt taken up. Theoretically therefore there need be no relation between the sign of the dilute solution and the relative amount of salt taken up with increasing concentration. Hypothetical diagrams of the electrical conditions in the cell are given. If we define the chemical effect as the P.D. observed in leading off at two points with equivalent concentrations of different salts we may say that the chemical effect of the protoplasm is very much greater than that of the cell wall.

The extraction AAS procedure used for the determination of lead in biological and related material has been adapted with only a minor modification to the determination of cadmium in body tissues and in fluids, water, foods, and airborne dusts. The modification involved an adjustment of volume to decrease the concentration effect, noted when a relatively large volume of distilled water was used to bring the MIBK layer into the neck of the volumetric flasks. A sensitivity of 0.010 ppm can be attained, and accuracies of analysis range from ±10% for fractions of a microgram of cadmium to about ±4% for microgram quantities of cadmium. Because of the known association of cadmium with some lead ores, one hundred samples of blood from workers in various lead industries were analyzed. No relationship between the concentrations of lead and cadmium was found. Further, after deletion of ten obviously aberrant results, a mean concentration of 0.2 μg of cadmium per 100 ml of blood was obtained for the remaining ninety ...

The properties of the Hagberg halving-lime method, the I.C.C. standard method and a new method, based on the stationary reaction stage, for colorimetric assay of α-amylase, are discussed and compared with each other. the first two were considered to be basically equivalent, and experimental comparison has been made only between the halving-time method and the new method. In the stationary-stage method (SSM), part of the reaction curve between log concentrations of the α-amylase sample solution and the corresponding linear extinction values of the iodine-stained samples, taken from the reaction exhibits a straight line relationship. This part is concluded to represent the stationary stage of the amylolytic hydrolysis reaction. the reaction end-point, at the intersection of the stationary stage straight line and the zero extinction line, reveals both the concentration of the sample solution and the absolute quantity of the sample substance needed to cause a zero extinction in the test conditions. The α-amylase activity values, obtained by the halving-time method, were found to be strongly dependent on the enzyme concentration of the sample solution, whereas in the SSM the detrimental concentration effect is eliminated. The α-amylase activity values obtained by SSM are consistently lower than the means of the corresponding values obtained by the halving-time method at each concentration of the sample solution.

The uptake of halothane given in constant concentration (1 per cent) was shown to be more rapid in a mixture with 70 per cent N2O than in one with 10 per cent N2O. This demonstrates that the uptake of a gas is influenced by the constituents of the mixture of which it is a component. Changes in the c

In Nitella the substitution of KCl for NaCl changes the P.D. in a negative direction. In some cases this change is lessened by adding solid CaCl2 to the solution of KCl. This may be due to lessening the partition coefficient of KCl or to decreasing the solubility of an organic substance which sensitizes the cell to the action of KCl. Little or no correlation exists between this effect of calcium and its ordinary antagonistic action in producing a balanced solution which preserves the life of the cell indefinitely. CaCl2 is negative to NaCl but positive to KCl. The effects of mixtures of KCl, NaCl, and CaCl2 are discussed. The concentration effect of a mixture of KCl + CaCl2 shows certain peculiarities due to action currents: these resemble those found with pure KCl. These studies and others on Nitella, Valonia, and Halicystis indicate that mobilities and partition coefficients are variable and can be brought under experimental control.

Rouse and Zimm have derived theories of viscoelastic properties of random coil polymers in dilute solutions, and Kirkwood and Auer that for rodlike polymers. Comparing these theories with each other in the form of the normalized dispersion curve, we may obtain direct information on the degree of internal freedom of polymer molecules.Many experimental investigations on viscoelasticity of coiling polymers have been made for dilute and for concentrated solutions. Experimental results for dilute solutions show almost quantitative agreement with the theories of Rouse or Zimm, but those for concentrated solutions a systematic disagreement. From these results, it is clear that concentration effect on the viscoelasticity still remains somewhat ambiguous even in the region of dilute solutions. This is not surprising, because all these theories are concerned only with the intrinsic quantities corresponding to infinite dilution without taking account of intermolecular interaction.In this study the dynamic intrinsic viscosity and intrinsic rigidity, therefore, are defined experimentally as follows, [η']=limc→0(η'-ηs)/ηsc, [G']=limc→0G'/c.Considering that, with changing concentration, all relaxation times involved change to some extent as was pointed out by Ferry, we define also the limiting value of the terminal relaxation time as(τ1)0=limc→0τ1(c).The complex rigidities are obtained by means of the torsional crystal method at the frequency of 39.2kc and the temperature of 30.0°C. The relaxation times are derived from the steady shear viscosities measured by a Ubbelohde dilution viscometer.As an example of the random coil conformation, the solutions of the high molecular weight polymethyl methacrylate (Mv=2.1×106) in chloroform were studied. The measured values for G'/c, (G"-ωηs)/c and τ1 were found to be in line with the concentration. The intrinsic rigidities and the limiting relaxation time were determined by extrapolating the experimental data to the zero concentration. The sets of the intrinsic rigidities and the limiting relaxation time thus determined were quantitatively in agreement with the values predicted by the Rouse theory.In the case of the rodlike conformation, poly-γ-methyl-D-glutamate (Mn=1.29×105) which was 100% α-helix in chloroform solutions was investigated. It was found that the measured values approached the theoretical dispersion curves due to Kirkwood and Auer as the concentration was lowered to infinite dilution.

1. 1.|The behaviour of the neutral soluble proteins of embryonic enamel when filtered through columns of Sephadex G-75 and G-100 resin was investigated. 2. 2.|The relative proportion of the protein which was retarded and which was excluded from the resin was dependent on the initial concentration of the protein solution. 3. 3.|Each of the peaks eluted from the Sephadex columns was studied by ultracentrifugation, amino acid analysis, and by its elution profile when rerun through the Sephadex column. All but one of the peaks were found to contain both high and low molecular weight material in a state of labile equilibrium. 4. 4.|The composition of the fractions which were retarded on the Sephadex columns was found to be dependent on both a concentration effect and the elution of distinctive chemical moieties at particular void-volume to elution-volume ratios. Each of the fractions which was retarded on the Sephadex columns formed high molecular weight aggregates of variable composition. 5. 5.|High molecular weight material which did not dissociate on dilution, and which was apparently unrelated to the interacting system, dissociated in 6 M urea, and was therefore also composed of non-covalently bonded aggregates. The average molecular weight of the aggregates was found to be 2.9·10 6 , and the estimated molecular weight of the smallest aggregate, 1.86·10 6 . 6. 6.|The results of these experiments characterize the enamel proteins as a multicomponent system involving different aggregate complexes of approximately the same size.

The sedimentation constant at the theta state at a finite concentration was calculated on the basis of Yamakawa's formulation, taking more rigorous account of hydrodynamical interaction. The results show that even at the theta state the concentration effect still remains and that ks, the coefficient of the first power of weight concentration, is proportional to M1/2.

The concentration effect of aqueous CO 2 on the reaction velocity of spinach leaf ribulose-1,5-diphosphate carboxylase has been reevaluated. The homotropic effect of CO 2 in the enzyme reaction supports the previously reported allosteric nature of the enzyme in the CO 2 -fixation process in chloroplasts. The concentration of CO 2 giving the half maximal reaction velocity, S 0.5 , has been calculated to be 1.47 × 10 −5 M.

Vacuum-ultraviolet luminescence of rare-gas solid solutions of XeAr, XeKr, and KrAr has been measured using excitation by slow electrons. The concentration effect has been studied on the spectra of mixtures at T = 5°K. It is shown that luminescence centers of three types — atomic, molecular and heteroatomic — are formed in the solutions. The bands corresponding to the molecular and heteroatomic centers appear at radiative decay of molecules which are formed in a crystal during excitation. The bands of atomic centers display a fine structure which is due to asymmetric distortion of the sorrounding lattice. Identification of the observed bands has been proposed.

Evidence of a critical concentration effect in dilute polymer solution has been obtained from light-scattering measurements in two ternary systems of the type polymer A–polymer B–solvent S. The root-mean-square end-to-end distance, (r2)1/2, of A was measured in a series of mixed solvents (B–S), differing from one another only in respect Of CB, the concentration of polymer B. The (r2)1/2 vs. CB curve exhibited a slight dip in the system polystyrene–polyvinyl acetate–benzene and a slight peak in the system polystyrene–polyvinyl acetate–butanone, at values of CB close to but not identical with the critical concentrations determined viscometrically for the same systems. The size, nature, and location of these light-scattering critical concentration effects are briefly discussed in the light of similar but better established viscosity effects.

The P.D. across the protoplasm of Valonia macrophysa has been studied while the cells were exposed to artificial solutions resembling sea water in which the concentration of KCl was varied from 0 to 0.500 mol per liter. The P.D. across the protoplasm is decreased by lowering and increased by raising the concentration of KCl in the external solution. Changes in P.D. with time when the cell is treated with KCl-rich sea water resemble those observed with cells exposed to Valonia sap. Varying the reaction of natural sea water from pH 5 to pH 10 has no appreciable effect on the P.D. across Valonia protoplasm. Similarly, varying the pH of KCl-rich sea water within these limits does not alter the height of the first maximum in the P.D.-time curve. The subsequent behavior of the P.D., however, is considerably affected by the pH of the KCl-rich sea water. These changes in the shape of the P.D.-time curve have been interpreted as indicating that potassium enters Valonia protoplasm more rapidly from alkaline than from acidified KCl-rich sea water. This conclusion is discussed in relation to certain theories which have been proposed to explain the accumulation of KCl in Valonia sap. The initial rise in P.D. when a Valonia cell is transferred from natural sea water to KCl-rich sea water has been correlated with the concentrations of KCl in the sea waters. It is assumed that the observed P.D. change represents a diffusion potential in the external surface layer of the protoplasm, where the relative mobilities of ions may be supposed to differ greatly from their values in water. Starting with either Planck's or Henderson's formula, an equation has been derived which expresses satisfactorily the observed relationship between P.D. change and concentration of KCl. The constants of this equation are interpreted as the relative mobilities of K+, Na+, and Cl- in the outer surface layer of the protoplasm. The apparent relative mobility of K+ has been calculated by inserting in this equation the values for the relative mobilities of Na+ (0.20) and Cl- (1.00) determined from earlier measurements of concentration effect with natural sea water. The average value for the relative mobility of K+ is found to be about 20. The relative mobility may vary considerably among different individual cells, and sometimes also in the same individual under different conditions. Calculation of the observed P.D. changes as phase-boundary potentials proved unsatisfactory.

The structure and the properties of micelles of surface-active substances in aqueous solution are briefly surveyed. Attention is paid mainly to solubilisation and methods for investigating the location of solubilised molecules. Kinetic concepts of micellar catalysis are examined and compared. The role of various factors (concentration effect, orientation, shift in pKa of reactants, change of environment) in the micellar effects observed in organic reactions is analysed. A list of 113 references is included.

The group effect in Acheta domesticus (L.) was more marked at 29 °C than, as previously described, at 35 °C. At 29 °C, methyl laurate at a concentration of 0.040 M increased the weight of both singly reared and group-reared males; at a concentration of 0.053 M it had no effect on group-reared larvae but increased the weight of singly reared males and decreased the weight of singly reared females.