A strategy for modeling microstructure in macroscopic simulations of welded material

With the increased precision in laser-welded structures, smaller and thinner parts can be joined. This magnifies the effect that microstructural changes due to the welding process have on the mechanical properties of the material. Although conventional welding processes are generally applied to work pieces of larger dimensions, the higher heat inputs and longer duration of the thermal cycle can have drastic effects on the microstructure. Multiscaled models can provide a method to achieve microscopic detail in a macroscopic simulation. The dual-mesh principle proposed here places microstructure domains at the nodes of a macroscopic finite-element (FE) calculation.     

A physically based model for microstructure development in a macroscopic heat-affected zone: Grain growth and recrystallization

The microstructure in new alloys is increasingly being engineered toward specific properties. Welding, however, alters or destroys this carefully constructed microstructure in the weld and the surrounding region, known as the heat-affected zone (HAZ). Modeling the influence of the entire thermal cycle of the welding process with a physically based model for the material can provide new understanding of the microstructure evolution due to the welding process. In this work, the phase-field method employed uses a physically based model to describe the motion of grain boundaries during welding. Via a unique dual-mesh strategy, calculation times for a macroscopic HAZ are drastically reduced while still maintaining sufficient detail for microstructure characterization.     

Phase I and pharmacologic study of 9-aminocamptothecin colloidal dispersion formulation given as a 24-hour continuous infusion weekly times four every 5 weeks

PURPOSE: 9-Aminocamptothecin (9-AC) is a water-insoluble camptothecin (CMP) derivative that inhibits normal topoisomerase I function. Schedule dependency was noted, with the greatest activity seen in the setting of greater than 24 hours exposure to lactone (L) concentrations > or = 10 nmol/L. In this phase I study, 9-AC was given by a continuous intravenous infusion over 24 hours once weekly times four every 5 weeks. PATIENTS AND METHODS: Twenty patients, of whom 16 had fluorouracil-refractory colorectal cancer (CRC), entered the study. Dose levels were 0.7 mg/m2 (n = 4), 1.4 mg/m2 (n = 3), 1.9 mg/m2 (n = 6), and 1.65 mg/m2 (n = 7). Detailed pharmacokinetic (PK) measurements of 9-AC L and carboxylate (C) were performed on day 1 of cycles 1 and 2. RESULTS: At 1.9 mg/m2, dose-limiting toxicity (DLT) was reached, with three of six patients having grade 4 neutropenia. At 1.65 mg/m2, one of seven patients had grade 4 neutropenia. Nonhematologic toxicity was modest, with diarrhea > or = grade 3 in two patients and lethargy > or = grade 3 in eight. PK/pharmacodynamic (PD) analyses showed marked interpatient variability. Steady-state concentrations (Css) of 9-AC L > or = 10 nmol/L (3.6 microg/L) were seen in five of seven patients at 1.65 mg/m2 and five of six patients at 1.9 mg/m2. Using the sigmoidal maximal effect (Emax) model, 9-AC L area under the concentration-time curve (AUC) and Css correlated with day 15 decrease in neutrophils (R2 = .47), but not platelets. CONCLUSION: The recommended phase II dose of 9-AC colloidal dispersion (CD) given as a 24-hour continuous infusion weekly for 4 of every 5 weeks is 1.65 mg/m2.     

Theory, not cultural context, will advance American psychology.

Comments on an article by J. J. Arnett (see record 2008-14338-003) regarding the assertion that American psychology focuses too narrowly on Americans while neglecting the other 95% of the world’s population. The authors agree with Arnett's call for greater attention to this issue. However, they fundamentally disagree with his position on issues related to generalizability and basic research. The goal of this comment is to provide a critical evaluation of Arnett’s primary arguments as well as to offer alternative strategies for facilitating scientific progress on cultural and diversity issues. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Spectral changes of the fluorescent acriflavine--(Feulgen) DNA dye complex at different temperatures: application of a new cryostat for measurements in reflected and transmitted light.

The fluorometric behaviour of cellular objects is influenced during excitation by two nearly independent phenomena: (1) by the photochemical reaction of the DNA/AF dye complex, and (2) by the energy transfer among several DNA/AF dye complexes. Both processes show a distinct temperature-dependent behaviour and can therefore be characterized by the analysis of the fluorescence spectra at different temperatures. All microfluorometric measurements were performed with a self-constructed cooling device. The cryostat permits measurements of the cellular fluorescence within a range of temperatures between 4 K and 300 K. The cooling unit operates in accordance with the 'Continuous Flow Principle' and allows the application of objectives up to a numerical aperture of 0.6.     

Applying Topological and Economical Principles in Catalyst Design: New Alumina–Cobalt Core–Shell Catalysts

Designing new and effective catalysts may be an art, but its consequences are very real and pragmatic. That said, chemists often build designs on ideal systems, whereas the manufacturing of chemicals requires catalysts that withstand varied feeds, harsh conditions and long exposure times. Moreover, economical considerations are often underestimated at the catalyst design stage. Here we discuss the inclusion of economical and topological considerations early on in the catalyst design process, giving as an example the synthesis and testing of a new type of alumina/cobalt Fischer–Tropsch catalysts.

     

When variability matters more than meaning: The effect of lexical forms on use of phonemic contrasts.

During the first half of the 2nd year of life, infants struggle to use phonemic distinctions in label–object association tasks. Prior experiments have demonstrated that exposure to the phonemes in distinct lexical forms (e.g., /d/ and /t/ in daddy and tiger, respectively) facilitates infants' use of phonemic contrasts but also that they struggle to generalize the use of phonemic contrasts to novel syllabic contexts (Thiessen, 2007; Thiessen & Yee, 2010). Further, in prior research, infants have been provided only with experience in lexical forms that refer to novel objects, while many lexical forms in the natural environment do not have easily identified visual referents. The experiments in this article show that even lexical forms without referents can facilitate use of phonemic contrasts. Additionally, the results indicate that when lexical forms provide infants with enough variability (for example, a consonant followed by multiple different vowels), infants are able to generalize to novel contexts. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Development and expression of autogrooming in the Mongolian gerbil, Meriones unguiculatus..

Observation data of 20 male adult gerbils indicate that they autogroomed their body parts in the following order: mouth-nose, face, ears, flank, ventrum, and tail. This is the identical order in which the autogroom matures during the 1st 33 days of life. Thus, the sequence of the fixed-action pattern follows the order in which it develops. The parallel sequencing increases the understanding of neurophysiological processes underlying movement patterns and also indicates how movement patterns evolve. (14 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Observation of the enhanced backscattering of light by the end of a tilted dielectric cylinder owing to the caustic merging transition

The scattering of light by obliquely illuminated circular dielectric cylinders was previously demonstrated to be enhanced by a merger of Airy caustics at a critical tilt angle. [Appl. Opt. 37, 1534 (1998)]. A related enhancement is demonstrated here for backward and near-backward scattering for cylinders cut with a flat end perpendicular to the cylinder's axis. It is expected that merged caustics will enhance the backscattering by clouds of randomly oriented circular cylinders that have appropriately flat ends.