Die Wasserstofflöslichkeit von Schlacken des Systems CaO–„FeO”–SiO2

Untersuchung der Löslichkeit des Wasserstoffs in homogenen flüssigen Schlacken des Systems CaO–?FeO”–SiO₂. Einfluß der Temperatur und der Sehlackenzusammensetzung. Erörterung des Mechanismus der Wasserstofflösung in flüssigen Schlacken.     

Current transport in conducting particle filled epoxies

The electrical contact resistance between isolated pairs of micron-sized gold particles has been measured as a function of their separation using apparatus constructed in house. When incorporated into a percolation model for current transport in a conducting particle filled insulator, the results of such measurements have been shown to be consistent with the observed variation of conductivity with filler content beyond the percolation threshold in gold filled epoxies. This has been tested further by using adsorbed alkanethiol monolayers to control the interparticle spacing in the composites, demonstrating the importance of the contact resistance for the macroscopic current transport properties. Received: 22 September 1997/Revised version: 30 October 1997/Accepted: 31 October 1997     

Blocking of classical complement pathway inhibits endothelial adhesion molecule expression and preserves ischemic myocardium from reperfusion injury

Myocardial injury after ischemia (I) and reperfusion (R) is related to leukocyte activation with subsequent release of cytokines and oxygen-derived free radicals as well as complement activation. In our study, the cardioprotective effects of exogenous C1 esterase inhibitor (C1 INH) were examined in a rat model of myocardial I + R (i.e., 20 min + 24 hr or 48 hr). The C1 INH (10, 50 and 100 U/kg) administered 2 min before reperfusion significantly attenuated myocardial injury after 24 hr of R compared to vehicle treated rats (P < .001). Further, cardiac myeloperoxidase activity (i.e., a marker of PMN [polymorphonuclear leukocyte] accumulation) in the ischemic area was significantly reduced after C1 INH treatment compared to vehicle treated animals (0.81 +/- 0.1, 0.34 +/- 0.13, 0.13 +/- 0.1 vs. 1.44 +/- 0.3 U/100 mg tissue, P < .001). In addition, C1 INH (100 U/kg) significantly attenuated myocardial injury and neutrophil infiltration even after 48 hr of reperfusion compared to vehicle treatment. Immunohistochemical analysis of ischemic-reperfused myocardial tissue demonstrated activation of classical complement pathway by deposition of C1q on cardiac myocytes and cardiac vessels. In addition, expression of the endothelial adhesion molecules P-selectin and intercellular adhesion molecule 1 (ICAM-1) was observed after reperfusion of the ischemic myocardium. In this regard, C1 INH administration abolished expression of P-selectin and ICAM-1 on the cardiac vasculature after myocardial ischemia and reperfusion. Blocking the classical complement pathway by exogenous C1 INH appears to be an effective means to preserve ischemic myocardium from injury after 24 and 48 hr of reperfusion. The mechanisms of this cardioprotective effect appears to be due to blocking of complement activation and reduced endothelial adhesion molecule expression with subsequent reduced PMN-endothelium interaction, resulting in diminished cardiac necrosis.     

Spectroscopic studies on chemically reacted (oxidized) coals

Solid material is often the main product of chemically reacted coal. In this study, elemental analysis and infrared molecular spectroscopy were therefore used for characterizing the structural changes during reaction. Three seam coals were oxidized in a controlled gas-solid reaction at different temperatures. A group analysis provided detailed quantitative figures on composition versus time of reaction. Assuming first-order reaction, values for rate constants, apparent energies of activation and frequency factors were calculated, and mechanisms of reaction have been proposed for different oxidation steps.     

Increased acceptance of the International Normalized Ratio (INR) as a monitoring parameter of oral anticoagulation therapy in Germany. GELIA Study Group

In 1994 the German Cardiac Society recommended the International Normalized Ratio (INR) instead of "Quick's test" for the long-term management of oral anticoagulation therapy. Parallel cardiac surgical centers in Germany and Switzerland started patient recruitment for the GELIA study (German Experience with Low Intensity Anticoagulation). By the end of 1996, 862 consecutive patients with mechanical heart valve replacement had been enrolled. According to the protocol of the GELIA study, intensity of anticoagulation, methods used to control the oral anticoagulation therapy as well as other factors relevant for the anticoagulation management are reported every three months. The so far accumulated data material of the GELIA study seemed, therefore, appropriate to analyze potential changes in the acceptance of INR during the time period 1993-1996. Potential differences in the anticoagulation management were analyzed separately according to the time of enrollment of patients and changes during the follow up period, e. g., a switch from "Quick's test" to INR. Taking the time of enrollment into account, the percentage of patients who had INR-controlled oral anticoagulation therapy increased from 0% (1993), 14.3% (1994), 63.2% (1995) to 74.2% in 1996. During the follow up, there was a change from "Quick's test" to INR controls in 7 patients (1994; 2.1%), 67 patients (1995; 10.5%) and 142 patients (1996; 17.3%) with a consequent increase of INR controlled patients to a total of 34.2% in 1994, 52.0% in 1995, and 73.9% in 1996.     

HYDROLIQUEFACTION OF TEXAS LIGNITE IN COAL- AND PETROLEUM-DERIVED SLURRY OILS

ABSTRACT

Hydroliquefaction of Texas lignite (68.5%. C daf) was conducted in a batch autoclave under hydrogen in a coal–derived slurry oil at 90 bar initial pressure for temperatures of 380–460^° C and residence time of 15–60 minutes, or a vacuum distillate from petroleum at 435^° C for 60 minutes and initial H₂–pressure of 60–150 bar, or a vacuum residue from the same petroleum at 435 and 460^° C for 60 minutes and initial H₂–pressure of 90–150 bar or tetralin at 435^°C, 60 minutes and 90 bar initial H₂–pressure. Red mud plus sodium sulfide were added as a catalyst for all experiments. Lignite conversion ranged from 50 to 83%. The products were separated into gases, residue, asphaltenes, oils B,P. above 200^° C, oils B.P. below 200^° C. Total liquid products from coal reached 57% in coal-derived slurry-oil, 56% in vacuum distillate and 64% in vacuum residue at optimum conditions with 32% of product oil B.P. below 200^° C in vacuum distillate and 24% in vacuum residue. When coprocessing lignite with vacuum residue at 120 bar initial pressure, 435^°C and 60 minutes residence time the total mass balance presented an oil yield of 73%. with 32% boiling below 200^°C.     

零件的五轴加工

采用三维CAD系统,能够设计更为复杂的零件。要加工这类零件的五轴加工程序的编制是很困难的事。但是,随着功能完善和容量强大CAD系统的推广,从设计、制造到切削加工过程就变得容易了。因此,五轴加工中心的应用日益普遍,越来越多的零件采用五轴加工中心进行加工。智能机床方案使生产零件的五轴加工更趋实用。