Modular Ligands for Dirhodium Complexes Facilitate Catalyst Customization

Although stereoselectivity is often the focus of ligand optimizations in catalysis, ligand modularity can be used to control many other properties of catalysts. For example, solubility, amenability to purification, and steric shielding of sensitive catalytic intermediates are all important, but seldom appreciated, functions of ligands. We describe a brief and modular approach to various homo‐ and heteroleptic lantern‐type rhodium(II) complexes and perform benchmarking studies with the new catalysts in common rhodium(II)‐catalyzed reactions. We demonstrate the power of ligand modularity by creating catalysts customized for aqueous catalysis or for applications in chemical biology.

     

A planning system based on Markov decision processes to guide people with dementia through activities of daily living.

Older adults with dementia often cannot remember how to complete activities of daily living and require a caregiver to aid them through the steps involved. The use of a computerized guidance system could potentially reduce the reliance on a caregiver. This paper examines the design and preliminary evaluation of a planning system that uses Markov decision processes (MDPs) to determine when and how to provide prompts to a user with dementia for guidance through the activity of handwashing. Results from the study suggest that MDPs can be applied effectively to this type of guidance problem. Considerations for the development of future guidance systems are presented.     

Crystallographic features of theγ-to-α transformation in a Nb-added transformation-induced plasticity steel

A Nb-bearing transformation-induced plasticity (TRIP) steel was control rolled and a certain amount of austenite was retained through appropriate heat treatment. Electron backscatter diffraction (EBSD) measurements were conducted on specimens deformed to various reductions, and the orientations of theα grains formed within individual prior-austenite grains were compared to those expected from the common correspondence relationships. While most of the bainite orientations cluster around the Bain circles formed by these relations, the polygonal (allotriomorphic) ferrite formed at the austenite grain boundaries does not obey any of these relations with respect to the neighboring austenite orientations. Grain-scale variant selection was observed in both the deformed and undeformed austenite grains. The crystallographic features of the deformation-induced ferrite transformation are also discussed.     

High temperature slow crack growth in polyoxymethylene

Brittle failure has been observed in polyoxymethylene during long‐term low‐level tensile loading at elevated temperatures. It is argued to be associated with slow crack growth via the breakdown of the localized planar fibrillar damage zones that form under these conditions. This phenomenon has been characterized using notched compact tension specimens tested under various static loads and at different temperatures. The specimen lifetime at a given load is found to decrease strongly with increasing temperature and to increase with molar mass at a given load and temperature. The associated crack‐tip fibrillar damage zones are shown to arise from the breakdown of more localized microfibrillar deformation zones, which in turn result from interlamellar cavitation in the early stages of tensile deformation.     

Nondeterministic Control for Hybrid Search

Hybrid algorithms combining local and systematic search often use nondeterminism in fundamentally different ways. They may differ in the strategy to explore the search tree and/or in how computation states are represented. This paper presents nondeterministic control structures to express a variety of hybrid search algorithms concisely and elegantly. These nondeterministic abstractions describe the search tree and are compiled in terms of first-class continuations. They are also parameterized by search controllers that are under user control and specify the state representation and the exploration strategy. The resulting search language is thus high-level, flexible, and directly extensible. The abstractions are illustrated on a jobshop scheduling algorithm that combines tabu search and a limited form of backtracking. Preliminary experimental results indicate that the control structures induce small, often negligible, overheads.     

Relativistic atomic data for EUV and X-ray lines in the highly charged Zn-like ions from Yb to U

The wavelengths and transition probabilities for EUV and X-ray lines in the spectra from Yb XLI to U LXIII along the zinc isoelectronic sequence have been calculated using a multiconfiguration Dirac-Fock (MCDF) model. Results are reported for the 4s²-4s4p, 4s4p-4p², and 4s4p-4s4d transitions. A comparison of the calculated wavelengths with the few experimental results available is also presented.     

Diffuse vascular ectasia of the antrum, duodenum, and jejunum in a patient with nodular regenerative hyperplasia. Lack of response to portosystemic shunt or gastrectomy

The case is reported of a 70 year old man who presented with severe anaemia because of chronic gastrointestinal blood loss. This loss was ascribed to vascular ectasia resembling the gastric antral vascular ectasia syndrome but extended to include the antrum, the duodenum, the jejunum, and, possibly, the cardiac area. This condition was associated with portal hypertension as a result of nodular regenerative hyperplasia. Consecutive treatments including sucralfate, prostaglandin E2, propranolol, organic nitrates, pentoxyphilline, corticosteroids, endoscopic sclerotherapy, portosystemic shunt, total gastrectomy, proved ineffective.     

A new innovative stabilization method for the protection of natural wood

The UV-light exposure of natural wood leads initially to a fast color change, and in the further stages to large chemical modifications and mechanical breakdown of the wood surface layer. Even in diffuse light exposure, prevailing in indoor conditions, the discoloration of wood is a serious esthetical drawback, for example, for furniture and parquetry.

Progress has been made with the development of new stabilizers, which offer a significant benefit compared to the currently used benzotriazole UV-absorbers. Using these new stabilizers the wood photo-protection against discoloration and the durability of clear and transparent pigmented coating systems can be significantly improved.     

An SIS waveguide heterodyne receiver for 600 HGz-635 GHz

A waveguide SIS heterodyne receiver using a Nb/AlO_X/Nb junction has been built for astronomical observations of molecular transitions in the frequency range 600 GHz - 635 GHz, and has been successfully used at the Caltech Submillimeter Observatory (CSO). We report double sideband (DSB) receiver noise temperatures as low as 245 K at 600 GHz -610 GHz, and near 300 K over the rest of the bandwidth. These results confirm that SIS quasiparticle mixers work well at submillimeter-wave frequencies corresponding to photon energies of at least 90% of the superconductor energy gap. In addition, we have systematically investigated the effect on the receiver performance of the overlap between first-order and second-order photon steps of opposite sign at these frequencies. The receiver noise increases by as much as 40% in the region of overlap. We infer potential limitations for operating submillimeter-wave Nb/AlO_x/Nb mixers.