Determination of organophosphate pesticides at a carbon nanotube/organophosphorus hydrolase electrochemical biosensor

An amperometric biosensor for oganophosphorus (OP) pesticides based on a carbon nanotube (CNT)-modified transducer and an organophosphorus hydrolase (OPH) biocatalyst is described. A bilayer approach with the OPH layer atop of the CNT film was used for preparing the CNT/OPH biosensor. The CNT layer leads to a greatly improved anodic detection of the enzymatically generated p-nitrophenol product, including higher sensitivity and stability. The sensor performance was optimized with respect to the surface modification and operating conditions. Under the optimal conditions the biosensor was used to measure as low as 0.15 μM paraoxon and 0.8 μM methyl parathion with sensitivities of 25 and 6 nA/μM, respectively.     

Total Synthesis of Pulvomycin D

A synthetic route to the pulvomycin class of natural products is presented, which culminated in the first synthesis of a pulvomycin, pulvomycin D. Key elements of the strategy include a pivotal aldol reaction which led to bond formation between the C24-C40 and the C8-C23 fragment. The remaining C1-C7 fragment was attached by a Yamaguchi esterification completing the assembly of the 40 carbon atoms within the main skeleton. Ring closure to the 22-membered lactone ring was achieved in the final stages of the synthesis by a Heck reaction. The completion of the synthesis required the removal of six silyl protecting groups in combination with olefin formation at C26-C27 by a Peterson elimination.     

Scientific realism: A challenge to physicists

If a physicist claims to be a realist, he or she must face at least the three problems outlined here: the careful specification of the validity limits of every theory and model used, the coherence relationships that must hold between two theories of the same physical system but on different cognitive levels, and the ambiguity in the ontology of two different formulations of empirically equivalent theories.This paper is dedicated to Professor Max Jammer in honor of his eightieth birthday. I have learned a great deal from his many excellent papers and books in history and philosophy of physics. Thank you and congratulations!     

Untersuchungen an Salzhydraten. IV. Thermische Zersetzung der Lithiumhalogenidkristallhydrate

Studies on Salt Hydrates. IV. Thermal Decomposition of Lithiumhalide Hydrates The thermal decomposition of LiX · nH₂O and LiX · nD₂O (X = Cl, Br, I; n = 1, 2, 3) is investigated on a thermobalance. There are differences in the stages of degradation depending on the starting hydrates and the anion radius. The thermal stability decreases with increasing quantity of water. Deuterates are of higher stability as hydrates.     

Stochastic dynamics of two-dimensional infinite-particle systems

The time evolution of an open system of infinitely many two-dimensional classical particles is investigated. Particles are interacting by a singular pair potentialU, and each particle is connected to a heat bath of temperatureT. The heat baths are represented by independent white noise forces and Langevin damping terms. Existence of strong solutions to the corresponding infinite system of stochastic differential equations is proved for initial configurations with a logarithmic order of energy fluctuations. Gibbs states forU at temperatureT are invariant under time evolution.     

Konstruktion vollständiger Minimalflächen von endlicher Gesamtkrümmung

Ohne Zusammenfassung Vorgelegt von J.C.C. Nitsche