Hybrid simulation of laser deep penetration welding

In laser deep penetration welding, the knowledge on the temperature history of the material is of great interest for the assessment of the quality properties of the weld. For this purpose a hybrid process model that enables the fast calculation of temperature distributions as a function of process parameters is applied. The interaction between laser and material is taken into account by a reduced keyhole model, which exploits a hierarchy in the spatial dimensions occurring at high feed rates. The resulting shape of a stationary keyhole is introduced as a Dirichlet boundary into a thermal finite element simulation in which it is moved through the workpiece according to the process control of the laser beam. The boundary is mathematically described by a level set function and immersed in a fixed computational mesh. The Dirichlet boundary condition is imposed using an embedded boundary method. The calculated temperature distributions are evaluated by means of bead on plate welds conducted in 0.9 mm thick sheets of 1.4301 (AISI 304) stainless steel.     

1,3-Diketones as Active Ligands in the Nickel-Catalyzed Linear Oligomerization of Olefins

The novel complex (4-cyclooctene-l-yl)- bis(trifluoroacetamido) nickel oligomerizes ethene to olefins of about 85% linearity. Unusual high activities of 11500 mol ethene/mol nickel were obtained. Also higher α-olefins such as propene, butene or octene could be oligomerized yielding 70-80% linear dimers. By using (4-cyclooctene-1-yl)(1,1,1,5,5,5-hexafluoro-2,4-pentanedionato) nickel activated by BF₃ the bulky olefin neohexene was converted selectively into dimers, which are linear, considering the C-C-linkage.     

Radioimmunotherapy of medullary thyroid cancer with iodine-131-labeled anti-CEA antibodies

This study evaluates the pharmacokinetics, dosimetry, toxicity and therapeutic potential of radiolabeled NP-4 and MN-14 anti-CEA antibodies in medullary thyroid cancer (MTC). METHODS: Eighteen patients with advanced MTC entered exploratory clinical studies with therapeutic doses of 131I-labeled NP-4 and MN-14 murine monoclonal antibodies (MAbs) reactive with carcinoembryonic antigen (CEA). Doses administered ranged from 46 mCi for 131I-MN-14 lgG to 195 mCi for 131I-MN-14 F(ab)2 in patients negative for human anti-mouse antibodies (HAMA). RESULTS: The radioconjugate blood half-life (T1/2) for the whole lgG was 42.5+/-5.0 hr compared to 18.8+/- 4.1 hr for the bivalent fragments. Tumor doses of 17.5+/-11.0 and 11.4+/-6.3 cGy/mCi were estimated for 131I-MN-14 lgG and F(ab)2, respectively. Tumor/red marrow dose ratios exceeded 3:1 for most lesions. Red marrow doses of up to 350 cGy generally could be delivered with < grade 4 toxicity. Seven of 14 evaluable patients showed evidence of anti-tumor effects lasting up to 26 months, based on physical exam, tumor markers or computed tomography. CONCLUSION: This study demonstrates that anti-CEA MAbs may be suitable for radioimmunotherapy of metastatic or recurrent MTC.     

Manipulating blood T cells and B cells from squirrel monkeys: some technical considerations

The squirrel monkey Saimiri sciureus is an experimental host for a range of human pathogens, and for the assessment of vaccine candidate antigens and vaccine strategies. This experimental host is thus particularly suitable for the follow-up of humoral responses. To understand some of the mechanisms that underlie the defense against experimental pathogens, there is a need of basic knowledge on cellular immune effectors also. The authors report here their experience in characterizing squirrel monkey blood T and B lymphocytes, and in studying in vitro induced activation and proliferation of T and B cells. Particular emphasis is given to the in vitro differentiation of squirrel monkey B cells into immunoglobulin secreting cells, with respect to Plasmodium falciparum antigens.     

鄂尔多斯盆地三叠系镜质体反射率与地热史

鄂尔多斯盆地庆36井三叠系镜质体反射率为0.61%～1.06%,其碳化梯度(R_m/km)较高,达0.36%.运用不同方法分析表明,该盆地中生代古地温梯度可达35～57℃/km,高于现今地温梯度.其它地温分析结果支持这一推论.推测高古地温梯度的原因可能是中生代时地壳厚度较薄和中侏罗世末一期热事件.讨论了高古地温梯度对于油气形成与勘探的影响.     

Breakage Prediction of Laminated Glass Using the “Sacrificial Ply” Design Concept

Laminated architectural glass has proven to be well suited for use in glazing systems that must resist wind-borne debris impacts. When the inner glass ply in a laminated window unit remains unbroken after wind-borne debris impacts on the outer glass ply, the integrity of the building envelope is preserved. A mechanics-based analytical model is developed to predict the cumulative probability of inner glass ply breakage in laminated architectural glass subjected to simulated wind-borne debris impacts on the outer glass ply. A nonlinear dynamic finite-element analysis is employed to compute stresses in each layer of the laminate due to impact. Based on the cumulative damage theory, the two-parameter Weibull distribution is used to characterize the cumulative probability of inner glass ply breakage. The analytical predictive model is calibrated using available experimental data on material parameters. Cumulative probabilities of inner glass ply breakage predicted by the analytical model are in agreement with the corresponding experimental data.     

Verwendung von Kohlendioxid bei technischorganischen Synthesen

Use of carbon dioxide in industrial organic syntheses . Although carbon dioxide is important as an abundant carbonaceous raw material, its utilization in chemical processes so far has been rather limited. This review covers the reactions of CO₂ employed in industry, such as the production of urea, the Kolbe-Schmitt reaction, the synthesis of cyclic organic carbonates, and the use of CO₂ in methanol synthesis. Interesting recent developments in CO₂ chemistry, especially the transition metal catalyzed reactions, are also elucidated. In addition to the synthesis of polymers and hydrocarbons, the production of oxygen-containing chemicals seems to be very profitable and attractive for future industrial applications. Not only can derivatives of formic acid and carbonic acid be formed but longer-chain carboxylic acids and their derivatives are also accessible by reactions of carbon dioxide with hydrocarbons such as alkynes, alkenes, and 1,3-dienes.     

Bulk quantity and physical properties of boron nitride nanocapsules with a narrow size distribution

A new synthesis route for the formation of boron nitride (BN) nanocapsules by means of a substitution process using single wall carbon nanotubes as templates, with yields of >95% is presented. It is also shown that these BN nanocapsules can act as ideal reference samples for the determination of the relative sp² to sp³ configuration in BN species, a value that is crucial for the physical properties of these nanostructures.     

Development of a vertical gradient freeze process for low EPD GaAs substrates

The main characteristics of low EPD 4 in semi-insulating and Si-doped conductive GaAs single crystals grown by a proprietary low thermal gradient vertical gradient freeze (VGF) technique on an industrial scale are presented.