High-pressure liquid chromatography fingerprinting of petroleums and petroleum products

Combined GC/HPLC fingerprinting of petroleums and process streams derived therefrom gives detailed information on their constituents. The silica gel-heptane system affords separation into classes of hydrocarbons which, together with dual u.v. and R.I. modes of detection, gives abundant information on the composition of such samples. GC on a medium-efficiency SCOT column is used as a complementary technique only. Interpretations of HPLC chromatograms for samples ranging from gasolines to bitumens are given.     

Objective determination of the consensual accommodation (author''s transl)

The direct and consensual accommodation of both eyes were determined by a modified coincidence refractometer. Young individuals with normal monocular and binocular vision revealed a close quantitative correspondence between the direct and the ipsi- and contralateral consensual accommodation. Experimental impairment of the function of the ciliary muscle by medical means caused disturbed consensual accommodation of both eyes. The weakening of the function of the ciliary muscle of one eye by instillation of, for example Homatropin leads to an important increase of the contralateral and diminution of the ipsilateral consensual accommodation. By the results of the investigations it was concluded: 1. that the regulation of the direct accommodation reflex is influenced also by the function of the ciliary muscle in the fixating eye and has stimulating and depressing components, 2. that the innervation of the nonfixating eye passes through an efferent neuron, from where the accommodation impulse emerges to both eyes. - The anatomically based relation between the direct and the ipsilateral and contralateral consensual accommodation allows one to use its quantitative determination in both eyes as a diagnostic test in afferent and efferent disturbances of the accommodation reflex.     

Heat transfer between particle beds and submerged surfaces

Theoretical modelling of heat transfer to particle beds comprises two sequential steps: transfer from the heating surface to contacting particles followed by transfer to the interior of the bed. Two different limiting case can be formulated for the second step: unmixed and homogeneously mixed bed. In the case, heat is transferred gradually via a repeated sequence of heat transfer in the gap between adjacent particles and conduction in the particulate material. In the second case, heat is transferred to the interior of the bed by mixing of particles which have previously attained the temperature of the heating surface. On the other hand, the mixing motion maintains a homogeneous lower temperature throughout the bed. Theory predicts a significant and easily measurable difference in the behaviour of heat transfer coefficients for the two regimes at long contact times t: unmixed beds ∝ $$ \sqrt t $$ and homogeneously mixed beds ∝ 1/t. For short times t, both regimes show the same behaviour, namely of t. From a theoretical standpoint, it makes sense to differentiate further between the behaviour patterns of unmixed beds: at long times t, instantaneous heat transfer coefficients are independent of heat transfer form the heating surface to adjacent particles. Comparison with experimental result from literature shows that the derived models, which are consistent, are suitable for describing the heat transfer from submerged surfaces to unmixed and mixed beds of particles.     

Rohrfertigung für den Reparaturbereich

Pipe fabrication for the repair sector. The paper discusses the changes in pipe fabrication that have taken place in recent years. These enable repair work to be carried out more efficiently, without thereby impairing the flexibility and speed of operation that are essential to maintenance work. A prerequisite for this is that work on the pipes be transferred to workshops. Only here is it possible for manual operations, such as manual welding, to be reduced to a minimum and be replaced by mechanized or semi-mechanized welding methods. The use of modern machines for bending the pipes is more economic than the welding in of pipe bends. Necking out of the pipes by mechanical means or the use of mechanically pre-fabricated connections permit optimum preparation of the weld seam for branch fittings. Any additional work on the pipes, where this is necessary, is carried out at workplaces specially designed for the purpose.     

Anisotropy of ductile fracture in hot-rolled steel plates-an application of the upset test

Upset testing of cylindrical specimens generates circumferential tensile stresses at the barreled surfaces. These stresses can be utilized in the same manner as the tensile stresses in the tension test to evaluate the ductility of materials. Using the upset test method, the anisotropy of ductile fracture in AISI 1045 hot-rolled steel plates was determined. Ductility parallel to the plane of inclusions is found to be ≈ 50 pet higher than that perpendicular to the inclusions. It is shown that the local surface strains at fracture in upset testing correlate well with the true zero-gage-length fracture strain in tension testing, provided the tensile stresses in the respective tests are in the same direction relative to the inclusion orientation. Thus, compression tests parallel to the inclusion direction, which generate tensile stresses perpendicular to the inclusions, can be utilized to measure ductility transverse to the fiber of wrought materials. This is particularly useful in determining the short transverse or through-thickness ductility in hot-rolled or forged materials having thin sections.     

Influence of surface active agents on the mass transfer across liquid—liquid interfaces—I. Dioxane—toluene—water-system

The instantaneons concentration of dioxane in freely suspended single toluene droplets was measured for an extremely wide range of droplet ages (0—600 sec) by means of a modified scintillation technique and the age dependence of the overall coefficients of mass transfer was evaluated. With increasing droplet age four consecutive exchange processes dominate with different decay constants for the concentration of solute which have very high, high, low, and very low exchange rates due to interfacial disturbances, turbulent internal mixing, transient internal mixing and desorption from the interface respectively.The decay constants of the first two processes decrease and the last two remain constant with increasing concentration of surface active agents. The overall decay constant decreases, goes through a minimum, increases, passes a maximum and finally decreases with increasing concentration of surface active agents. An explanation for this behaviour is given.     

Early diagnosis of rheumatoid arthritis

On the basis of own observations of courses the author adopts a definite attitude to the early symptomatology of the rheumatoid arthritis. During the first weeks of the rheumatoid arthritis the following symptoms are found: articular syndromes, more frequently in form of obstinate polyarthralgias, mono-oligoarthritis, accompanied by morning rigidity and accelerated BSR as well as impairment of the general condition. In the majority of the patients only the tentative diagnosis rheumatoid arthritis may be made. After a one to three months' course of the disease the diagnosis becomes more probable. It is above all based on constancy and symmetry, characteristic localisation of the articular process, morning rigidity, radiologically paraarticular loosening of the structure and morphological symptoms of an acute and subacute synovialitis. 6 to 12 months after the beginning of the disease a clinical picture forms which allows to make the diagnosis of a certain or classical rheumatoid arthritis in accordance with the criteria of the ARA. The occurrence of a high activity of multiple affection of the joints (permanent symmetrical polyarthritis including the small joints of the hands and feet), distinctive morning rigidity, high fever and much accelerated BSR, beginning with the first weeks of the disease, speaks for the possibility of the development of an arthrovisceral form of the course of rheumatoid arthritis.     

Modification of human platelet adhesion on biomaterial surfaces by protein preadsorption under static and flow conditions

Biomaterial-induced thrombosis remains one of the main complications of vascular implant devices. Preadsorbed proteins on the biomaterial/blood interface will modify the adhesion and activation of platelets (PTLs) during the initial contact-phase. Our results clearly show that PTL-adherence on biomaterials is influenced not only by protein preadsorption, but also by flow conditions. The covalent coating of TCPS and glass by phosphorylcholine (PC) induces a significant decrease of PTL adhesion but leads to a slight, but nevertheless significant activation of PTL, which was detected by the induction of P-selectin expression using FACS analysis. Methodologically, the visualization of PTL adhesion gave more reliable results for measurement of PTL adhesion than the cell-enzyme immunoassay (EIA) for P-selectin. Human citrated plasma caused an inhibition of PTL. It is probable, that the contained sodium citrate may inhibit PTL adhesion by its calcium ion-binding capacity. The flow experiment as dynamic system is in our view absolutely essential for the evaluation of biomaterials for vascular prosthesis, and is in accordance with the international standards. The results of the experiments also suggest that investigations under static and flow conditions are needed to determine the influence of protein adsorption on mixed blood cell populations, for example, on PTL and PMN mixtures/co-cultures in order to achieve a better simulation of the in vivo situation.