Application of macroscopic balances to the identification of gross measurement errors

A systematic method is presented which is capable of both detecting the presence of grossly biased measurement errors and locating the source of these errors in a bioreactor through statistical hypothesis testing. Equality constraints derived from material and energy balances are employed for the detection of data inconsistencies and for the subsequent identification of the suspect measurements by a process of data analysis and rectification. Maximum likelihood techniques are applied to the estimation of the states and parameters of the bioreactor after the suspect measurements have been eliminated. The level of significance is specified by the experimenter while the measurments are assumed to be randomly, normally distributed with zero mean and known variances. Two different approaches of data analysis, batchwise and sequential, that lead to a consistent set of adjustments on the experimental values, are discussed. Several examples based on the fermentation data taken from literature sources are presented to demonstrate the utility of the proposed method, and one set of data is solved numerically to illustrate the computational aspect of the algorithm.     

Noncomplementarity in base sequences between the cohesive ends of coliphages 186 and lambda and the formation of interlocked rings between the two DNA's

The half molecules of 186 DNA have been isolated by the Hg(II)–Cs₂SO₄ density gradient centrifugal ion technique. The buoyant densities of the two halves in CsCI at 25°C. are 1.713 and 1.709 g./cm.³, corresponding to GC contents of 54% and 50%, respectively. Similarly, 5-bromouracil labeled λ DNA halves were separated. The isolation of the four DNA halves made it possible to test for homology in base sequences between the cohesive ends of λ and those of 186. There was no indication of any significant homology in base sequences between the cohesive ends of the two DNA's, as indicated by the absence of a band with intermediate buoyant density in CsCI when either half of 186 DNA was annealed with either half of 5-bromouracil labeled λ DNA and then centrifuged. The lack of cohesion between the two DNA's made it possible to demonstrate unequivocally the formation of interlocked rings (catenanes) between the two DNA's. The existence of a dimeric catenane is evidenced by the formation of a species of intermediate buoyant density when 5-bromouracil labeled λ DNA is cyclized in the presence of cyclic 186 DNA of a relatively high concentration. The molecular weight of one DNA relative to the other can be calculated from the position of the dimeric catenane in a density gradient by using the method of Baldwin. The result was in complete agreement with our previous measurements from the sedimentation coefficients and by electron microscopy. The probability of dimeric catenane formation when one DNA is cyclized in the presence of another DNA is discussed. The experimental results agree with the theoretical expectation.     

高胆固醇高脂肪膳食对家兔β-VLDL组成及其与巨噬细胞相互作用的影响的初步研究

给家兔喂以1％胆固醇及10％菜油(A组)或猪油(B组)50多天后A组血胆固醇水平(824.2±265.1mg/dl)明显低于B组(1666±693.8mg/dl);A组甘油三酯水平(51.9±19.1mg/dl)亦低于B组(104±40.2mg/dl)。二组家兔的β—VLDL的脂类组成无差别,但A组β—VLDL的apoE高于B组,分别为45.2％及37.5％。高分子量apoB(apoB_h)为33.6％,低于B组β-VLDL(47.3％)。A组β-VLDL促进小鼠腹腔巨噬细胞胆固醇堆积的程度大于B组,可能与apoE含量高有关。我们认为多不饱和脂酸减轻动脉粥样硬化(As)的作用不在于改变脂蛋白构成后阻碍泡沫细胞的形成而是促进β—VLDL从体内清除。     

Second virial coefficient of alpha-crystallin

Light scattering studies were performed on bovine alpha-crystallin measuring the scattering intensities as a function of scattering angle, concentration, and temperature. The data yielded the molecular weight, radius of gyration, and second virial coefficient of alpha-crystallin at different temperatures. The second virial coefficient increased with increasing temperature. Both the enthalpy and entropy of solution of alpha-crystallin are positive. The Flory theta temperature was found to be 271 K.