Remarkable stereoselectivity switch in synthesis of carbonyl substituted N-arylamidrazones with low lipophilicity

Reaction of carbonyl substituted hydrazonoyl chlorides with amines usually leads to Z-configured amidrazone derivatives via nucleophilic substitution of the chlorine atom. Surprisingly, N,N-dimethylcarboxamide substituted hydrazonoyl chlorides yielded E-amidrazones when dialkylamines were used as nucleophilic reagent. The lipophilicities of the obtained amidrazones were found to be drastically reduced compared to their corresponding carboxanilides.     

Synthesis of high‐molecular‐weight linear methacrylate copolymers with spiropyran side groups: Conformational changes of single molecules in solution and on surfaces

P(BMA‐co‐HEMA‐spiropyran) was synthesized by reversible addition fragmentation chain transfer (RAFT) polymerization of butyl methacrylate (BMA) and 2‐(trimethylsilyloxy)‐ethyl methacrylate (HEMA‐TMS), removal of the TMS‐protective groups, and the polymer analogous esterification of the hydroxyethyl side chains with a spiropyran containing a carboxylic acid group. UV‐induced conformational changes of the synthesized macromolecules and low‐molecular‐weight spiropyran molecules were studied. Rate constants and half‐life times of the ring closure reaction from zwitterionic merocyanine to the spiropyran species were determined in the presence and absence of mica‐dispersed particles in toluene both with the free spiropyran and the polymer‐bound spiropyran. Scanning force microscopy was used to visualize the conformation of spiropyran‐decorated single macromolecular chains and agglomerated polymer‐bound merocyanine adsorbed on mica. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1274–1283, 2009     

ESPI solution for non-contacting MEMS-on-wafer testing

Rapid progress in the field of micro-electro-mechanical systems (MEMS) makes the development of appropriate measuring and testing means timely. Characterizing the mechanical properties of MEMS structures at a very early stage of manufacturing is a challenging task for quality assurance in this field. The paper describes a new solution that is based upon the vibration analysis of the microparts. The nanometer amplitudes are detected by advanced electronic speckle pattern interferometry (ESPI). A specific signal processing technique has been applied to make the solution robust. Comprehensive numerical simulations provide the theoretical base for the HNDT concept. A laboratory system for 4″ wafer has been built, and extensive tests show that such key properties as e.g. the thickness of springs or membranes can be determined exactly. Automated frequency scanning and corresponding digital image processing open the way to reliable and fast industrial systems for MEMS testing on wafer level.     

Quasiconformal groups, Patterson-Sullivan theory, and local analysis of limit sets

We extend the part of Patterson-Sullivan theory to discrete quasiconformal groups that relates the exponent of convergence of the Poincaré series to the Hausdorff dimension of the limit set. In doing so we define new bi-Lipschitz invariants that localize both the exponent of convergence and the Hausdorff dimension. We find these invariants help to expose and explain the discrepancy between the conformal and quasiconformal setting of Patterson-Sullivan theory.

     

Functional assessment of patients with spasmodic dysphonia

Assessment of function in patients with spasmodic dysphonia is necessary to confirm diagnosis, plan therapy, predict response, and assess effectiveness of treatment. This task is difficult because symptom severity fluctuates, the test environment is artificial, and the objective parameters used to measure vocal function may not adequately reflect the handicap experienced by the patient. Available methods for assessing these patients are reviewed and the utility of each considered, particularly in managing patients with botulinum toxin therapy. Assessment should include a battery of tests, including subjective perceptual ratings and direct physical measurements.     

Nanogram determination of arsenic in biological reference materials by non-destructive Compton suppression neutron activation analysis

Summary Non-destructive epithermal neutron activation analysis in conjunction with Compton suppression has been applied to determine arsenic in seven biological standard reference materials from the National Institute of Standards and Technology. The accuracy is in excellent agreement with all the certified values and compilation results. For four of the materials detection limits between 1–4 ng/g were easily achieved while for three others they ranged from 18–50 ng/g. Overall analytical precision typically varied between 2–4% for five of the reference materials while for two other it was between 12–16%. These methods clearly demonstrate that through a judicious approach of anti-coincidence techniques, nanogram quantities of arsenic can be reliably determined without the need for labor intensive chemical separations.