Changes in hemostasis in ischemic heart disease

The relationship between changes in blood coagulation, the occurrence and severity of risk factors of ischemic heart disease and the clinical condition of the patient was investigated. The at risk group of patients 42.2% had more than 3 pathological parameters. Intravascular blood coagulation was not activated in any of the patients. In patients with acute myocardial infarction (MI), 62.2% had more than 3 pathological parameters on the first day of MI development. Demonstrable activation of intravascular blood coagulation was found in 28.2% of these patients. On day 5 of MI, activation of intravascular blood coagulation was recorded in 57.7% of the patients treated by classical approach and in 15.4-30.8% of the patients on thrombolytic treatment. In the at risk group, primary hemostasis and the fibrinolytic system were more affected, in patients with MI the whole hemostatic mechanism was involved. On day 5 of MI, in patients with classical therapy pathological laboratory findings still persisted or were even more deteriorated, particularly increases in fibrinogen level. At that time, in patients on thrombolytic therapy no substantial changes of initial values were recorded. No correlation was found to exist between changes in hemostasis and the risk profile or between changes in hemostasis and the clinical severity of MI. The obtained results justify the administration of antithrombotic substances, especially in patients with unstable angina pectoris. On observing time constraints, administration of thrombolytics is justified in MI. (Fig. 9, Ref. 25.)     

Si/SiGe heterojunction bipolar transistor with base doping highly exceeding emitter doping concentration

A Si/Si/sub 0.8/Ge/sub 0.2/ heterojunction bipolar transistor was fabricated having emitter, base and collector contacts at the wafer surface. The base doping concentration amounted to 10/sup 19//cm/sup 3/ which was 20 times the emitter concentration. Due to the pronounced difference in bandgap energy a current gain of 17 was reached.<>     

An immune cell-selective interleukin 4 agonist

Interleukin 4 (IL-4) is a pleiotropic cytokine. Of the cell types responsive to IL-4, T cells express one IL-4 receptor (IL-4R) type, IL-4Ralpha/IL-2Rgamma (class I IL-4R), whereas endothelial cells express another type, IL-4Ralpha/IL-13Ralpha (class II IL-4R). It was hypothesized that IL-4 variants could be generated that would be selective for cell types expressing the different IL-4Rs. A series of IL-4 muteins were generated that were substituted in the region of IL-4 implicated in interactions with IL-2Rgamma. These muteins were evaluated in T cell and endothelial cell assays. One of these muteins, containing the mutation Arg-121 to Glu (IL-4/R121E), exhibited complete biological selectivity for T cells, B cells, and monocytes, but showed no activity on endothelial cells. Receptor binding studies indicated that IL-4/R121E retained physical interaction with IL-2Rgamma but not IL-13Ralpha; consistent with this observation, IL-4/R121E was an antagonist of IL-4-induced activity on endothelial cells. IL-4/R121E exhibits a spectrum of activities in vitro that suggest utility in the treatment of certain autoimmune diseases.     

Numerical calculation of electron optical aberrations

A numerical method for the accurate calculation of aberration figures in systems with a straight optical axis is concisely outlined. The method involves computing a fundamental set of paraxial rays, and then directly ray-tracing a judiciously chosen set of deviations from these paraxial rays, that enable the direct plotting of aberration figures. This method avoids using complicated aberration integrals, and can directly handle the effects of high-order aberrations and asymmetry errors. A fast general predictor-corrector method for the numerical ray-tracing is also presented.     

Observation of Unconventional Dynamics of Domain Walls in Uniaxial Ferroelectric Lead Germanate

Application of scanning probe microscopy techniques such as piezoresponse force microscopy (PFM) opens the possibility to re‐visit the ferroelectrics previously studied by the macroscopic electrical testing methods and establish a link between their local nanoscale characteristics and integral response. The nanoscale PFM studies and phase field modeling of the static and dynamic behavior of the domain structure in the well‐known ferroelectric material lead germanate, Pb₅Ge₃O₁₁, are reported. Several unusual phenomena are revealed: 1) domain formation during the paraelectric‐to‐ferroelectric phase transition, which exhibits an atypical cooling rate dependence; 2) unexpected electrically induced formation of the oblate domains due to the preferential domain walls motion in the directions perpendicular to the polar axis, contrary to the typical domain growth behavior observed so far; 3) absence of the bound charges at the 180° head‐to‐head (H–H) and tail‐totail (T–T) domain walls, which typically exhibit a significant charge density in other ferroelectrics due to the polarization discontinuity. This strikingly different behavior is rationalized by the phase field modeling of the dynamics of uncharged H–H and T–T domain walls. The results provide a new insight into the emergent physics of the ferroelectric domain boundaries, revealing unusual properties not exhibited by conventional Ising‐type walls.     

Evaluation of an in situ sampling probe for its accuracy in determining particle size distributions from flames

An in situ sampling probe for flames is evaluated for any biases with respect to size distributions in a given size and concentration range. Ultrafine metal particles (Pd, Pt) suspended in argon gas are added to a laminar diffusion flame, burning with argon-diluted methane. Samples of combustion aerosol are extracted from the flame via a small orifice and immediately quenched with nitrogen. The size distribution of the metal particles, recorded at various sampling positions in the flame, is found to be but little affected by the flame and the sampling procedure. The distribution of carbonaceous soot particles from an unseeded flame at a fixed sampling position is not shifted upon seeding but coexists next to the peak from the metallic flame additive. It is concluded that droplets of volatile combustion products, formed in the sampling system through homogeneous nucleation, do not significantly contribute to the soot particle signal. An investigation of the photoelectric yield of the samples implies significant changes of the surface properties of the metal particles during the combustion process. This seeding method offers a new path to study chemical processes in the flame, especially heterogeneous and catalytic reactions of flame gases with particles.     

Comparison of the chemical properties of iron and cobalt porphyrins and corrins

Density functional calculations have been used to compare various geometric, electronic and functional properties of iron and cobalt porphyrin (Por) and corrin (Cor) species. The investigation is focussed on octahedral M(II/III) complexes (where M is the metal) with two axial imidazole ligands (as a model of b and c type cytochromes) or with one imidazole and one methyl ligand (as a model of methylcobalamin). However, we have also studied some five-coordinate M(II) complexes with an imidazole ligand and four-coordinate M(I/II) complexes without any axial ligands as models of other intermediates in the reaction cycle of coenzyme B12. The central cavity of the corrin ring is smaller than that of porphine. We show that the cavity of corrin is close to ideal for low-spin Co(III), Co(II), and Co(I) with the axial ligands encountered in biology, whereas the cavity in porphine is better suited for intermediate-spin states. Therefore, the low-spin state of Co is strongly favoured in complexes with corrins, whereas there is a small energy difference between the various spin states in iron porphyrin species. There are no clear differences for the reduction potentials of the octahedral complexes, but [Co(I)Cor] is more easily formed (by at least 40 kJ mole(-1)) than [Fe(I)Por]. Cobalt and corrin form a strong Cobond;C bond that is more stable against hydrolysis than iron and porphine. Finally, Fe(II/III) gives a much lower reorganisation energy than Co(II/III); this is owing to the occupied d(z2) orbital in Co(II). Altogether, these results give some clues about how nature has chosen the tetrapyrrole rings and their central metal ion.     

Influence of the gas atmosphere on restructuring and sintering kinetics of nickel and platinum aerosol nanoparticle agglomerates

The kinetics of the primary particle growth and the restructuring of nanoparticle agglomerates of Ni and Pt were studied under variation of temperature and gas composition. The aerosol particles used in the study were produced by spark discharge into nitrogen as carrier gas. Restructuring was monitored by measuring the mobility equivalent diameter by SMPS after different residence times in a tempered volume. To determine the kinetics of primary particle growth, samples were taken over a range of residence times for TEM analysis. These experiments were conducted in reducing atmospheres and in pure nitrogen to study the effect of surface state on the kinetics of the processes. To quantify sintering kinetics, a multi-stage sintering model based on the reduction of the surface energy was fitted to the experimental results.

A strong dependence of the primary particle growth and the agglomerate restructuring on the surface state of the particles was found. Both processes were accelerated strongly with increasing purity of the particle surfaces. The model yielded an activation energy for the primary particle growth of Ni-agglomerates in pure nitrogen (99.99%) of about 80 kJ/mol which was decreased for reduced Ni and Pt particles to a value of about 50 kJ/mol. The kinetics of restructuring was much faster than the one for primary particle growth. This enables the seperation of the manipulations of agglomerate structure and primary particle size.     

Counting efficiencies of six commercial particle counters

Counting efficiencies of a condensation nuclei counter (TSI 3020), a white-light optical particle counter (Climet CI-8060) and four laser instruments (PMS LAS-X, LAS-250X, LPC 525 and HP-LAS) were determined relative to the LAS-X.

Measurements were made in the geometric diameter range of 0.1–4 μm using latex spheres as well as monodisperse organic and inorganic particles produced by a vibrating orifice generator.

The high-pressure in-line counter (HP-LAS) shows a nonlinear response to gas velocity which can be taken into account by a calibration. The lower detection limits (50% points) of the conventional laser counters (LAS-X and LAS-250X) agree within 0.05 μm with their nominal specifications; for the white-light counter (CI-8060) the actual lower limit is at about 0.4 μm. For all counters, the degree of inlet losses for larger particles varies greatly with inlet design and flow velocity of each counter.