Preparation of an ion-selective electrode by chemical treatment of copper wire for the measurement of copper(II) and iodide by batch and flow-injection potentiometry

The preparation of an ion-selective electrode by chemical treatment of copper wire and its application for the measurements of copper (II) and iodide ions is described. The proposed reaction mechanism at the sensing surface, which explains the response of the electrode to Cu²⁺ and iodide ions, is discussed. The prepared electrode was suitable for direct potentiometric measurements of iodide and copper (II) in batch experiments down to concentrations of 1 × 10^–5 mol L^–1. A tubular electrode, prepared in the same way, may be used as a potentiometric sensor in a flow-injection analysis for Cu (II) and/or iodide determinations.     

Interaction between model poly(ethylene terephthalate) thin films and weakly ionised oxygen plasma

Model films of poly(ethylene terephthalate) were treated by oxygen plasma in order to quantify the etching rate and estimate the contribution of charged and neutral particles to the reaction probability. Model films with a thickness of 50 nm were deposited on a quartz crystal of a microbalance (QCM) by spin‐coating technique. The samples were exposed to oxygen plasma with the positive ion density of 4 × 10¹⁵ m^?3 and neutral oxygen atom density of 6 × 10²¹ m^?3. The etching rate was determined from the QCM signal and was 4.7 nm s^?1. The etching was found rather inhomogeneous as the atomic force microscopic images showed an increase of the surface roughness as a result of plasma treatment. The model films were completely removed from the surface of the quartz crystals in about 12 s. Knowing the etching rate and the flux of oxygen atoms to the surface allowed for calculation of the reaction probability which was found to be rather low at the value of 1.6 × 10^?4. Copyright © 2011 John Wiley & Sons, Ltd.     

Etching of polyethylene terephthalate thin films by neutral oxygen atoms in the late flowing afterglow of oxygen plasma

Films of polyethylene terephthalate were deposited on quartz crystals and exposed to oxygen atoms to study their etching characteristics and quantify the etching rate. Oxygen (O) atoms were created by passing molecular oxygen through plasma created in a microwave discharge. The discharge power was fixed at 250 W, while the pressure of oxygen was 50 Pa. Before exposure to oxygen atoms, a thin polymer film of polyethylene terephthalate (PET) was deposited uniformly over a crystal with a diameter of 12 mm. The crystal was mounted on a quartz crystal microbalance to accurately determine the thickness of the polymer film. The polymer film was exposed to O atoms in the flowing afterglow. The density of O atoms was measured with a cobalt catalytic probe mounted next to the sample and was determined to be 1.2 × 10²¹ m^–3. Samples were treated with O atoms for different periods of up to 120 min. The thickness of the film decreased linearly with treatment time. After 90 min of treatment, a 65‐nm‐thick polymer film was completely removed. Therefore, the etching rate was 0.5 nm/min, so the interaction probability between an O atom and an atom in the sample was extremely low, just 1.4 × 10^–6. Samples treated for different periods were investigated by atomic force microscopy and X‐ray photoelectron spectroscopy to examine the etching characteristics of O atoms in the flowing afterglow. Copyright © 2012 John Wiley & Sons, Ltd.     

Vergleich, Dimensionierung und Realisierung einphasiger Power Factor Correctors minimalen Realisierungsaufwands

In the future laws and restrictions will limit the amplitudes of the low frequency harmonics of mains currents of rectifier systems. While diode bridges are very simple, compact and cheap, their input current shows high low-order harmonics. In the past various rectifier systems have been developed that avoid low-order input current harmonics by means of active current control. The significantly reduced input filter results in a small and compact total rectifier system. In this paper different rectifier systems are discussed and compared. Since industry is interested in simple and cheap solutions the rectifier systems are discussed under these considerations. Besides an introduction of different power circuits and control schemes, the systematic choice of the power semiconductors is presented.     

3,7-bis-(4-trifluoromethylphenyl)-1,5,3,7-dioxadiazocine: a novel cyclic product from a reaction of 4-trifluoromethyl-benzenediazonium chloride and methylamine-formaldehyde

4-Substituted benzenediazonium chlorides react with methylamine- formaldehyde mixture at ?5 to ?10°C -and controlled pH to afford the novel 3,7-bis-(4-X-aryl)-1,5,3,7-dioxadiazocines rather than the expected 1-(4-X-aryl)-3-hydroxymethyl-3-methyltriazenes or related dimeric products.     

Space vector-based analytical analysis of the input currentdistortion of a three-phase discontinuous-mode boost rectifier system

In this paper the low frequency harmonic distortion of the mains current of a three-phase single-switch discontinuous-mode boost-rectifier is calculated. The system analysis is based on application of space vector calculus and on substitution of discontinuous time shapes within a pulse period by quasicontinuous time shapes. The quasicontinuous time shapes are defined by averaging over the pulse period. The dependency of the shape of the input currents on the voltage transformation ratio is given for various control methods in analytical form. The results of the theoretical analysis are verified by digital simulation and by measurements on a laboratory model. A good consistency of the results has been found     

A thermodynamic approach, using speciation studies, towards the evaluation and design of bone-seeking radiopharmaceuticals as illustrated for 117mSn(II)-PEI-MP

Blood plasma modeling has proved effective in the evaluation of clinical observations recorded for baboon and rat tests with ¹⁵³Sm- ethylenediaminetetraphosphonic acid (EDTMP) as well as for ¹⁶⁶Ho-EDTMP. In the search for a cure for metastatic bone cancer, ^117mSn with its conversion electrons of discrete energies shows low bone marrow toxicity, providing the opportunity to increase the administered dose. Selective accumulation in lesions would capitalize on this advantage. The 10-30 kDa fraction of the water-soluble polymer polyethyleneimine, functionalized with methylene phosphonate groups (PEI-MP) and labeled with ^99mTc, has shown selective uptake into bone tumours. This paper relates the speciation of Sn(II)-PEI-MP and other known ^117mSn(II) containing bone-seeking radiopharmaceuticals in blood plasma. Apparent formation constants for the complexation of Sn^II with PEI-MP, DTPA, HEDP and other important blood plasma ligands were measured potentiometrically or estimated by linear free energy relationships (LFER). These data were added to the ECCLES database in order to construct a blood plasma model for Sn^II. From this model it is predicted that Sn^II will remain bound to the polymer (PEI-MP) in blood plasma and therefore, have only slight reticuloendothelial uptake. Preliminary primate studies indeed proved that the complex between Sn^II and PEI-MP remains intact in blood plasma, which is consistent with the observation for PEI-MP labeled with ^99mTc. From these data, it was also possible to explain in retrospect the lower bone uptake, the slow blood clearance and the liver uptake of the agents ^117mSn(II) DTPA and ^117mSn(II) HEDP agents as reported in the literature.     

A 14-bit 250 kS/s two-step inverter-based incremental $$\varSigma \varDelta$$ ADC for CMOS image sensor in $$0.18\,\upmu \hbox {m}$$0.18μm technology

This paper presents an ultra-low-power, bulk-driven, source-degenerated fully differential transconductor (FD-OTA), operating in subthreshold region. The source-degeneration (SD) and bulk-drive ensure linearity and rail-to-rail input swing. The flipped voltage follower and SD resistor perform V–I conversion in input core with power efficient class AB mode of operation. The reduction in open loop gain and gain bandwidth (GBW) of bulk-drive is compensated by applying partial positive feedback at diode connected MOSFET pair. The current gain from input core to output load side is set (1:1) in OTA₁ and (1:4) in OTA₂. The OTA₂ offers increased transconductance and GBW whereas self-cascode load increases the output impedance and overall gain of the FD-OTAs. Both the input core and common source self-cascode load operate in class AB mode so these FD-OTAs provide enhanced slew rates. These OTAs have been employed to implement Biquadratic low-frequency G_m-C filter suitable for bio-signal applications. The proposed OTA₂ has used dual supply voltage of ± 0.3 V and dissipates around 70 nW power and provides 62 dB FD-open loop gain with GBW of 7.73 kHz while driving the FD-load of 2 × 15 pF. The Cadence VIRTUOSO environment using UMC 0.18 µm CMOS process technology has been used to simulate the proposed circuit. The Simulation results verified fully differential total harmonic distortion of ? 72 dB, for 1.2 V_p–p signal at 200 Hz frequency in unity gain configuration with resistive degeneration of 1 MΩ for OTA₁.