Steady-state concentration distribution of ampholytes in isoelectric focusing in a linear immobilized pH gradient

The equation of balance between electrophoretic and diffusional mass flows in the steady state of isoelectric focusing is analyzed. To create the pH gradient, a model system composed of only one Immobiline is used. The solution is found for the case of a small sample concentration, but without assumptions about linear "focusing force" and constant (linear) conductivity profiles. The effect of sample concentration on the final concentration profile is also evaluated. At high sample concentrations, it is demonstrated that the steady-state distribution is essentially non-Gaussian and results in a considerably lower concentration maximum as compared with low sample levels.     

Purification of cytochrome b5 from pig testis microsomes by isoelectric focusing in an immobiline pH gradient

To evaluate the diagnostic value of thrombopoietin (TPO, c-mpl ligand) measurements, and clarify the regulatory mechanisms of TPO in normal and in thrombocytopenic conditions, the plasma TPO concentration was determined in normal individuals (n = 20), umbilical cord blood (n = 40), chronic idiopathic thrombocytopenic purpura (ITP; n = 16), in severe aplastic anaemia (SAA; n = 3), chemotherapy-induced bone marrow hypoplasia (n = 10), myelodysplastic syndrome (MDS; n = 11), and sequentially during peripheral blood progenitor cell transplantation (n = 7). A commercially available ELISA and EDTA-plasma samples were used for the analysis. The plasma TPO concentration in the normals and umbilical cord blood were 52 +/- 12 pg/ml and 66 +/- 12 pg/ml, respectively. The corresponding values in patients with SAA and chemotherapy-induced bone marrow hypoplasia were 1514 +/- 336 pg/ml and 1950 +/- 1684 pg/ml, respectively, and the TPO concentration, measured sequentially after myeloablative chemotherapy and peripheral blood progenitor cell transplantation, was inversely related to the platelet count. In contrast, the plasma TPO recorded in patients with ITP (64 +/- 20 pg/ml) and MDS (68 +/- 23 pg/ml) were only slightly higher than normal levels. In conclusion, TPO levels were significantly elevated in patients in which bone marrow megakaryocytes and platelets in circulation were markedly reduced, whereas TPO levels were normal in ITP patients, and only slightly increased in the MDS patients. These latter patients displayed a preserved number of megakaryocytes in bone marrow biopsies. Our data support the suggestion that megakaryocyte mass affects the plasma TPO concentration. In thrombocytopenic patients a substantially increased plasma TPO implies deficient megakaryocyte numbers. However, TPO measurements do not distinguish between ITP and thrombocytopenia due to dysmegakaryopoiesis, as seen in MDS patients.     

螺旋管在小倍线充填中的应用及充填倍线公式修正

为解决小倍线充填管道局部压力过大、管路磨损严重等问题,本文提出用螺旋管增阻调压的结构与实施方案.结合计算流体力学（computational fluid dynamics,CFD）对增阻调压结构与实施方案进行模拟分析,基于模拟计算的结果提出增加螺旋管道增阻调压结构后计算充填倍线的修正公式.研究结果表明,在2 m·s^-1的模拟流速下,螺旋管增阻调压结构所产生的阻力可达同等高度直管的10.1~16.8倍,在保证料浆连续输送的前提下可以有效的起到增阻降压的作用.结合数值模拟的充填倍线修正公式能够较为完善地计算增阻降压后的有效充填倍线.     

Microstructures induced by a stress gradient in a nickel-based superalloy

The evolution of the microstructure of single crystals of a nickel-based superalloy during high temperature (1323 K, 1050°C) creep in bending has been studied. Bending provides both tensile and compressive stress gradients; consequently the effects of varying stress conditions on the evolution of the morphology of the γ′ precipitates can be determined from a single specimen. The morphological changes were analysed by scanning electron microscopy using image analysis techniques and by transmission electron microscopy, then described by dimensionless parameters. We discuss the dependence of the morphological changes in the superalloy on the stresses acting in the sample (magnitude and sign). We also discuss the driving mechanisms for the observed morphological changes.     

Sequential protein analysis from single identified neurons of Aplysia californica. A microelectrophoretic technique involving polyacrylamide gradient gels and isoelectric focusing

Electrophoresis in polyacrylamide gradient gels and isoelectric focusing in polyacrylamide gels of capillary size are powerful tools for the analysis of molecular weight and charge properties of small protein samples. This is demonstrated using identified neurons from the abdominal ganglion of the sea hare Aplysia californica. Certain cell-specific peptides, which are considered to be neurosecretory, have been shown to be water soluble when ethylene glycol was employed as a mobilizing agent. Although the mode of action of ethylene glycol is not yet understood, this method may be of value for various extraction procedures. The application of a new staining method that is preferential for separations of sodium dodecyl sulfate-proteins yields information about the charge of water-insoluble proteins which has so far been inaccessible. Preliminary results gained by a small, two-dimensional mapping procedure as well as optical density separation patterns of two different nuclear protein fractionation from a single isolated nucleus outline further possibilties of the microgel techniques.