Kinetics of partly diffusion controlled reactions. II. Competition between physical and chemical kinetics. Theoretical treatment

We propose a quantitative method for computing the time-dependent value of the apparent rate constant of a bimolecular reaction in the liquid phase in The model proposed permits one to determine the time-dependence of the apparent rate constant of a bimolecular process in the case where a competition The results are necessary for the understanding of the deactivation of excited electronic states by various quenchers. As a matter of fact, it appears that in numerous experimental cases, such a competition is physically significant.     

Extending orderings on formally real fields

Archiv der Mathematik -     

Excitation intensity dependence of lateral photocurrent in InGaAs/GaAs dot-chain structures

Optical properties of multi-layer In_xGa_1 − xAs/GaAs dot-chain heterostructures are studied by means of lateral photoconductivity (PC). Effects of carrier generation and recombination on the photoresponsivity of deep defects and quantum dot arrays are considered. It is shown that the radiative recombination significantly affects the lateral PC spectra thus leading to a nonlinear dependence of photocurrent on excitation intensity. For ground state excitation of the quantum dots the photocurrent nonlinearities are determined by a competition of both generation and recombination processes which include thermal activation.     

Comparative Analysis of the Properties of Tween‐20, Tween‐60, Tween‐80, Arlacel‐60, and Arlacel‐80

Foamability and foam stability, emulsifying power, surface tension, and interfacial tension were investigated for Tween‐20 (polyoxyethylene sorbitan monolaurate), Tween‐60 (polyoxyethylene sorbitan monostearate), Tween‐80 (polyoxyethylene sorbitan monooleate), Arlacel‐60 (Sorbitan stearate), and Arlacel‐80 (Sorbitan oleate). Among all the surfactants tested for their foaming power and foamabilty, Arlacel‐60 and Arlacel‐80 showed the best results; the foaming power and foamability was found to be 100%. The surfactants having foam stability more than 50% can be considered as metastable and those less than 50% are considered as low‐stability foams. In case of surface tension and interfacial tension property measurements, Arlacel‐80 showed the best results. At 1% surfactant concentration, the surface tension and interfacial tension of Arlacel‐80 was found to be 29.9 dynes/cm and 1.1 dynes/cm at 30°C ambient temperature. Also, Arlacel‐60 was found to exhibit the best emulsifying power among all the surfactants tested. At 30°C, the emulsifying property of Arlacel‐60 was 6 hours.     

Beitr?ge zur Untersuehung von Alkaloiden

Ohne Zusammenfassung     

Demuškin groups of rank ℵ0 as absolute galois groupsas absolute galois groups

We produce a complete classification of the groups mentioned in the title. This result complements earlier work of Serre and Labute [Lab2] and is further motivated by the basic question: which profinite groups occur as groups of automorphisms of algebraically closed fields?     

Polarization spectroscopy of positive and negative trions in an InAs quantum dot

Using polarization-sensitive photoluminescence and photoluminescence excitation spectroscopy, we study single InAs/GaAs self-assembled quantum dots. The dots were embedded in an n-type, Schottky diode structure allowing for control of the charge state. We present here the exciton, singly charged exciton (positive and negative trions), and the twice negatively charged exciton. For non-resonant excitation below the wetting layer, we observed a large degree of polarization memory from the radiative recombination of both the positive and negative trions. In excitation spectra, through the p-shell, we have found several sharp resonances in the emission from the s-shell recombination of the dot in all charged states. Some of these excitation resonances exhibit strong coulomb shifts upon addition of charges into the quantum dot. One particular resonance of the negatively charged trion was found to exhibit a fine structure doublet under circular polarization. This observation is explained in terms of resonant absorption into the triplet states of the negative trion.     

Network Design for Express Shipment Delivery

Service network design problems arise at airlines (passenger and cargo), trucking companies, railroads, etc., wherever there is a need to determine cost minimizing routes and schedules, given constraints on resource availability and level of service. We focus on a particular service network design application, namely, the express shipment delivery problem, and we develop models and a solution technique designed specifically for large-scale express delivery problems with time windows. Using data from an express delivery company, we demonstrate that our approach can produce savings in total operating costs and provide a valuable tool for making decisions at strategic and tactical levels.