Electrochemistry of surface grafted copper(II) benzoate complexes

Glassy carbon electrodes were grafted with carboxyphenyl groups by reduction of 4-carboxyphenyldiazonium tetrafluoroborate and these modified electrodes were characterised by cyclic voltammetry and ac impedance measurements. Cu(II) was reacted with the carboxyphenyl groups in the film to give a surface voltammetric response for the immobilised Cu(II)/Cu(I) couple. The results indicated an ECEC mechanism, in which the chemical steps correspond to the change of coordination environment following the electron transfer steps. The relaxation half-life time for the Cu(I) species formed after electron transfer was estimated at (140 ± 11) s. The large value of the peak width of 200 mV was analysed by modelling the voltammograms and the large value of the full width at half maximum (FWHM) could be explained by dispersion in the formal potentials of Cu centres present in a variety of environments in the films studied. An ECEC mechanism (scheme of square) is proposed for the electron transfer reaction considering that the chemical step after reduction of the Cu(II) complex corresponds to conformational changes within the attached layer. Experimental data clearly show that the oxidation of the reduced film can take place from different Cu(I) complexes formed along the reduction to the fully relaxed Cu(I) species.     

Problems in the extreme value analysis

Engineering design for structural safety is largely based on the statistics of natural hazards. These statistics are utilized by applying the theory of extremes, which predicts a cumulative distribution function of the extreme events. The parameters of this distribution are found by a fit to the historical extremes and the probabilities of potentially disastrous events are then calculated. It is pointed out here that this procedure often results in underestimation of the risk. This is because wrong probability plotting positions are widely used and because theoretical extreme value distributions are asymptotic only, so that in many cases they bring misleading information to the analysis. The means to avoid these problems in the extreme value analysis are outlined.     

Dynamic simulation of product process

During 90’s Nokia utilized Concurrent Engineering (CE) process in mobile phone business successfully. Strong growing of the company, more complex technologies, maturing markets and changes in competition has increased the need to develop the product process of the company to keep its position as an agile, innovative and productive product developer. Dynamic simulation approach has been one of the activities among other product process re-engineering efforts in the company.This paper describes the approach and “Product Process Decision Simulation” (PPDS) solution as the first implemented application of the approach. A dynamic model of product development has been created and applied to manage product process complex dynamic behavior on system level in order to reduce product development cycle times, slippages and costs as well as improve perceived product quality. The key contribution of the simulation solution is to provoke facilitated discussion in order to gain shared understanding of interdependencies and dynamic causes and effects in product process.The implementation and frequent simulation workshops have started in June 2006 and about 500 R&D people have already participated.     

Camptothecin‐7‐yl‐methanthiole: Semisynthesis and Biological Evaluation

The introduction of a methylenthiol group at position 7 of camptothecin was carried out in four steps. This preparation also yielded the corresponding disulfide, which behaves as a prodrug due to its reactivity with glutathione. Assessment of their antiproliferative activities, investigations of their mechanism of action, and molecular modeling analysis indicated that the 7‐modified camptothecin derivatives described herein maintain the biological activity and drug–target interactions of the parent compound.     

Non-destructive Case Depth Determination by Means of Low-Frequency Barkhausen Noise Measurements

The availability of a fast and reliable method for non-destructive case depth determination which can be used to directly monitor the quality of various heat treatment processes is of great interest. Conventionally hardened steel components are analyzed by means of depth-resolved microhardness measurements providing the case hardening depth (CHD) of the material. However, as a consequence of mechanical destruction, the investigated part cannot be used in its original state anymore and needs to be replaced by a twin part whose properties might be different. In this work, a new approach of non-destructive CHD determination based on Barkhausen noise analysis with an excitation frequency of 0.5 Hz is described. The use of a low frequency allows to enhance the penetration depth of the external magnetic field and to reduce the eddy current damping of the filtered Barkhausen (BN) signal at the same time. In this way, simultaneous information about the hard case and the soft base material core is experimentally accessible. Various measurands derived from the detected BN signals are sensitive to the different magnetic properties of the case and the core. The so-obtained correlations with the measured CHD can be used for non-destructive CHD determination by means of appropriate calibration data. The investigated sample set consists of cylindrical parts of 18CrNiMo7-6 which were case-hardened and ground in order to provide graded CHD values up to 3.6 mm. The sensitivity of the tested low-frequency method will be quantitatively demonstrated over the complete range of interest and its potential for industrial applications will be discussed.     

Comparison of burnt area estimates derived from satellite products and national statistics in Europe

Burnt area maps based on satellite observations are frequently used in calculations related to fire regime, such as those of carbon dioxide emissions. Nevertheless, burnt area estimates between products vary widely, and validation against independent data is scarce, especially for Europe. Here we compare two active fire maps (the ATSR World Fire Atlas and the Moderate Resolution Imaging Spectroradiometer (MODIS) Active Fire Product) and two fire scars maps (the L3JRC and the MODIS Burned Area Product) to independent national statistics taken from 22 European countries between 1997 and 2008. We also tested the coincidence between satellite products derived by calculation of the fraction of active fires that were confirmed by a subsequent drop in reflectance. As a large proportion of fire pixels (between 40% and 66%, depending on the product) is located on urban land or crop fields, filtering out fires located on these land uses greatly improves the agreement between satellite-based burnt area estimates and national statistics and it also improves the coincidence between satellite products. The MODIS Active Fire Product appears to be most suitable for use as a proxy for burnt area patterns, showing a high correlation to national statistics (R² = 0.9), relatively low spatial and temporal heterogeneity and only a slight underestimation of the total burnt area (19 000 ha year^–1). Unfiltered products show cases of substantial wildfire overestimation in all products, mainly attributable to anthropogenic activity, in the case of active fire products, and drought-induced vegetation dieback, in that of fire scar maps. Thus, filtering out fires on anthropogenic land uses seems to be essential when analysing patterns of forest fires from satellite observations. However, if agricultural fires are to be included, a combination of MODIS Active Fire and MODIS Burned Area products is recommended. We obtained that such combination shows low temporal and spatial heterogeneity and the highest coincidence between satellite products (25%), although the correlation to national statistics is not very high (R² = 0.67) and clearly underestimates the total burnt area (187 000 ha year^–1).     

Bipartite Matching in the Semi-streaming Model

We present the first deterministic 1+ε approximation algorithm for finding a large matching in a bipartite graph in the semi-streaming model which requires only O((1/ε)⁵) passes over the input stream. In this model, the input graph G=(V,E) is given as a stream of its edges in some arbitrary order, and storage of the algorithm is bounded by O(npolylog?n) bits, where $n = \lvert {V}\rvert $ . The only previously known arbitrarily good approximation for general graphs is achieved by the randomized algorithm of McGregor (Proceedings of the International Workshop on Approximation Algorithms for Combinatorial Optimization Problems and Randomization and Computation, Berkeley, CA, USA, pp. 170–181, 2005), which uses Ω((1/ε)^1/ε ) passes. We show that even for bipartite graphs, McGregor’s algorithm needs Ω(1/ε) ^Ω(1/ε) passes, thus it is necessarily exponential in the approximation parameter. The design as well as the analysis of our algorithm require the introduction of some new techniques. A novelty of our algorithm is a new deterministic assignment of matching edges to augmenting paths which is responsible for the complexity reduction, and gets rid of randomization. We repeatedly grow an initial matching using augmenting paths up to a length of 2k+1 for k=?2/ε?. We terminate when the number of augmenting paths found in one iteration falls below a certain threshold also depending on k, that guarantees a 1+ε approximation. The main challenge is to find those augmenting paths without requiring an excessive number of passes. In each iteration, using multiple passes, we grow a set of alternating paths in parallel, considering each edge as a possible extension as it comes along in the stream. Backtracking is used on paths that fail to grow any further. Crucial are the so-called position limits: when a matching edge is the ith matching edge in a path and it is then removed by backtracking, it will only be inserted into a path again at a position strictly lesser than i. This rule strikes a balance between terminating quickly on the one hand and giving the procedure enough freedom on the other hand.     

Temperature effects of PTFE diffusers

Poly(tetrafluoroethylene) (PTFE) is the most commonly used diffuser material in ultraviolet irradiance measurements. The temperature sensitivities of five PTFE diffusers were measured over a broad temperature range. The transmittance change varied from −0.015%/°C to −0.1%/°C. At 19 °C there was an unexpected abrupt change in transmittance ranging from 1% to 3%. This change is due to the change of the crystal structure of PTFE at 19 °C. Temperature sensitivity decreases significantly the accuracy of high precision measurements, especially if the temperature of the diffusers is not stabilized.     

Action of Cyclodextrins on Germinating Seeds and on Micropropagated Plants

Effects of cyclodextrins on germinating barley seeds and on the growth of micropropagated strawberry plants were investigated. Treatment of barley seeds with α- or β-cyclodextrins resulted in a similar delay of germination as reported earlier [1]. The delay of germination occurred with agarose-immobilized as well as with free cyclodextrins. Since penetration of immobilized cyclodextrins into the seeds is limited, it was concluded that the delay resulted from complexation of growth factors. Soluble cyclodextrins caused a growth retardation with micropropagated strawberry plants and certain morphological changes resembling the ones observed when the action of auxins is enhanced in the respect to cytokinins.     

Stability of Parallel Queueing Systems with Coupled Service Rates

This paper considers a parallel system of queues fed by independent arrival streams, where the service rate of each queue depends on the number of customers in all of the queues. Necessary and sufficient conditions for the stability of the system are derived, based on stochastic monotonicity and marginal drift properties of multiclass birth and death processes. These conditions yield a sharp characterization of stability for systems where the service rate of each queue is decreasing in the number of customers in other queues, and has uniform limits as the queue lengths tend to infinity. The results are illustrated with applications where the stability region may be nonconvex.