Disappearance Rate ot the Anticoagulant Effect of Heparin

1975 ◽  
Author(s):  
C.A.M. de Swart ◽  
A. Nijmeijer ◽  
J. W. N. Akkerman ◽  
J. J. Sixma
Keyword(s):  
Simple Technique ◽  
Single Injection ◽  
Anticoagulant Activity ◽  
Accurate Determination ◽  
Anticoagulant Effect ◽  
Disappearance Rate ◽  
Heparin Activity ◽  
Large Single Dose ◽  
Plasma Heparin

The disappearance of the anticoagulant activity of a intravenously administered well-defined commercial heparin was followed in human and dogs utilizing a diluted activated partial thromboplastin time (Marder) and an anti-Xa-assay (Tin). The anticoagulant activity was followed after the injection of a large single dose. More accurate determination of the relation between heparin level and disappearance rate was achieved by continuous infusion with different heparin dosages. The anticoagulant effect was linearly related with dosage administered above a certain minimum threshold. This is in agreement with disappearance curves obtained after a single injection that can be described by the formula:(in which S represents the heparin activity, K1 and K2 represent constants and K3 is the integration constant). References: Marder, V. J.: A simple technique for the measurement of plasma heparin concentration during anticoagulant therapy. Thromb. Diath. Haemorrh. 24, 230–239, 1970.Yin, E. T., Wessler, S.: Plasma heparin: A unique, practical, submicrogram sensitive assay. J. Lab. Clin. Med. 81, 298-310, 1973.

Studies on the Anti-Heparin Activity of Serum

1962 ◽  
Vol 07 (01) ◽  
pp. 188-196 ◽  
Author(s):  
T Holger-Madsen
Keyword(s):  
Plasma Level ◽  
Normal Serum ◽  
Thrombin Time ◽  
Original Activity ◽  
Platelet Poor Plasma ◽  
Normal Platelet ◽  
Heparin Resistance ◽  
Heparin Activity ◽  
Plasma Heparin

SummaryThe anti-heparin activity of serum was investigated by adding serum to normal, platelet-poor plasma and determining the heparin thrombin time.BaSO4-adsorbed serum and serum from platelet-poor plasma proved to exert a considerably less marked anti-heparin activity than plain serum. Even in platelet-poor serum, adsorbed with BaSO4 some anti-heparin activity still remained, but by far the greater part of the original activity had disappeared. In some patients, in whom determination of the plasma heparin thrombin time has shown increased heparin resistance, the serum may also exert a greater anti-heparin activity than normal serum. In patients on anticoagulant therapy with phenylindanedione even a considerable lowering of the prothrombin-proconvertin plasma level did not entail any reduction in the anti-heparin activity of the serum as compared with normal serum.

A quantitative approach to inner shell losses

1978 ◽  
Vol 36 (1) ◽  
pp. 526-527 ◽  
Author(s):  
R.D. Leapman ◽  
P. Rez ◽  
D.F. Mayers
Keyword(s):  
Energy Transfer ◽  
Cross Section ◽  
Cross Sections ◽  
Accurate Determination ◽  
Background Intensity ◽  
Core Excitation ◽  
Quantitative Basis ◽  
Cross Section Differential ◽  
Bound Electrons

Microanalysis by EELS has been developing rapidly and though the general form of the spectrum is now understood there is a need to put the technique on a more quantitative basis (1,2). Certain aspects important for microanalysis include: (i) accurate determination of the partial cross sections, σx(α,ΔE) for core excitation when scattering lies inside collection angle a and energy range ΔE above the edge, (ii) behavior of the background intensity due to excitation of less strongly bound electrons, necessary for extrapolation beneath the signal of interest, (iii) departures from the simple hydrogenic K-edge seen in L and M losses, effecting σx and complicating microanalysis. Such problems might be approached empirically but here we describe how computation can elucidate the spectrum shape.The inelastic cross section differential with respect to energy transfer E and momentum transfer q for electrons of energy E0 and velocity v can be written as

Fast calibration of CBED patterns for quantitative analysis

1993 ◽  
Vol 51 ◽  
pp. 674-675
Author(s):  
M.A. Gribelyuk ◽  
M. Rühle
Keyword(s):  
Reciprocal Lattice ◽  
Accurate Determination ◽  
Incident Beam ◽  
Crystal Thickness ◽  
Structure Model ◽  
Beam Direction ◽  
Transmitted Beam ◽  
Reciprocal Vector ◽  
On Line

A new method is suggested for the accurate determination of the incident beam direction K, crystal thickness t and the coordinates of the basic reciprocal lattice vectors V1 and V2 (Fig. 1) of the ZOLZ plans in pixels of the digitized 2-D CBED pattern. For a given structure model and some estimated values Vest and Kest of some point O in the CBED pattern a set of line scans AkBk is chosen so that all the scans are located within CBED disks.The points on line scans AkBk are conjugate to those on A0B0 since they are shifted by the reciprocal vector gk with respect to each other. As many conjugate scans are considered as CBED disks fall into the energy filtered region of the experimental pattern. Electron intensities of the transmitted beam I0 and diffracted beams Igk for all points on conjugate scans are found as a function of crystal thickness t on the basis of the full dynamical calculation.

Computer-Assisted High-Re Solution TEM

1990 ◽  
Vol 48 (1) ◽  
pp. 162-163
Author(s):  
F.A. Ponce ◽  
H. Hikashi
Keyword(s):  
Signal To Noise Ratio ◽  
Accurate Determination ◽  
Computer Software ◽  
Video Camera ◽  
Image Contrast ◽  
Objective Lens ◽  
Computer Assisted ◽  
Optical Parameters ◽  
Astigmatism Correction

The determination of the atomic positions from HRTEM micrographs is only possible if the optical parameters are known to a certain accuracy, and reliable through-focus series are available to match the experimental images with calculated images of possible atomic models. The main limitation in interpreting images at the atomic level is the knowledge of the optical parameters such as beam alignment, astigmatism correction and defocus value. Under ordinary conditions, the uncertainty in these values is sufficiently large to prevent the accurate determination of the atomic positions. Therefore, in order to achieve the resolution power of the microscope (under 0.2nm) it is necessary to take extraordinary measures. The use of on line computers has been proposed [e.g.: 2-5] and used with certain amount of success.We have built a system that can perform operations in the range of one frame stored and analyzed per second. A schematic diagram of the system is shown in figure 1. A JEOL 4000EX microscope equipped with an external computer interface is directly linked to a SUN-3 computer. All electrical parameters in the microscope can be changed via this interface by the use of a set of commands. The image is received from a video camera. A commercial image processor improves the signal-to-noise ratio by recursively averaging with a time constant, usually set at 0.25 sec. The computer software is based on a multi-window system and is entirely mouse-driven. All operations can be performed by clicking the mouse on the appropiate windows and buttons. This capability leads to extreme friendliness, ease of operation, and high operator speeds. Image analysis can be done in various ways. Here, we have measured the image contrast and used it to optimize certain parameters. The system is designed to have instant access to: (a) x- and y- alignment coils, (b) x- and y- astigmatism correction coils, and (c) objective lens current. The algorithm is shown in figure 2. Figure 3 shows an example taken from a thin CdTe crystal. The image contrast is displayed for changing objective lens current (defocus value). The display is calibrated in angstroms. Images are stored on the disk and are accessible by clicking the data points in the graph. Some of the frame-store images are displayed in Fig. 4.

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