Determination of cadmium, lead and thallium in highly saline hemodialysis solutions by potentiometric stripping analysis (PSA)

Potentiometric stripping analysis (PSA) was investigated to assay simultaneously cadmium, lead and thallium present as contaminants in highly saline solutions used in hemodialysis. The saline matrices were sodium, potassium, magnesium and calcium chlorides, sodium acetate, sodium bicarbonate and glucose, which constitute concentrates for hemodialysis. A 1000 μg mL⁻¹ Hg(II) solution was used to prepare the mercury film electrode (MFE) and to carry out the stripping step. After a 30 s accumulation interval the analytes were simultaneously detected in the saline matrices without using masking agents. Determination limits of 80 ng L⁻¹ for cadmium and thallium, and 50 ng L⁻¹ for lead were calculated and a R.S.D. ranging from 0.5 to 2.2% (n = 3) was obtained measuring the analytes directly in commercial hemodialysis saline solutions. Recoveries from spiked samples ranging from 94.6 to 102.0% were obtained. The investigated metals were found in concentrations ranging from 2.7 to 5.7 μg L⁻¹ for cadmium, 27.7 to 75.8 μ L⁻¹ for lead and 9.6 to 18.7 μg L⁻¹ for thallium in commercial hemodialysis solutions. The PSA method showed to be adequate to the quality control of saline concentrates for hemodialysis.     

5-Hydroxy-2H-pyrrol-2-ones and not 2-aminofurans are the cycloaddition products between alkyl isocyanides and benzyliden-1,3-diketones

New insights into the cycloaddition reaction between alkyl isocyanides and benzyliden-1,3-diketones are reported. 5-Hydroxy-N-substituted-2H-pyrrol-2-ones and not substituted furans, as previously reported, are formed. The proof of the structure relies on a thorough analytical investigation and X-ray crystallography.     

Reliability improvement of single-poly quasi self-aligned bicmos bjts using base surface arsenic compensation

A key issue in modern microelectronics is to improve and optimise device performance and reliability without excessively increasing fabrication costs. In this paper we will show how it is possible to improve the reliability of single-poly silicon quasi self-aligned BJTS of an advanced 0.5μm BiCMOS technology by means of base surface As compensation without any additional mask. By carefully optimising the process parameters it is possible to maintain unchanged the characteristics of the intrinsic transistor compared to the reference one (without compensation) with only a slight increase of the parasitic base resistance, as proven by extensive statistical measurements. Depending on the As dose an increase of the device lifetime by up to four orders of magnitude can be obtained.     

Measurements and extractions of parasitic capacitances in ULSI layouts

This paper deals with the extraction of parasitic capacitances of interconnects in submicron layouts. It is well known that, in integrated circuits, the signal delay due to interconnects is comparable to that of gates. This aspect becomes particularly important, for example, during the design of clock trees in high-speed applications. In general, capacitance extraction is carried out with software tools but they should be validated on a set of geometrical structures, which have been accurately characterized and that are representative of the circuit layouts. Experimental characterization of these structures and their set up in a golden set of measures is still a challenging task. In this paper, we first describe some experimental approaches to measure capacitances of structures from the golden set and in particular we identify a high accuracy transducer based on pass-gate transistors. We then propose a software implementation of the floating random walk algorithm that solves the drawbacks in the extraction of capacitances of interconnects in a nonhomogeneous medium as an industrial layout. Finally, experimental and simulation results are presented, validating the adopted approach.     

Tools for contactless testing and simulation of CMOS circuits

Short channel effects in MOSFETs are responsible for time-dependent hot-carrier luminescence, synchronous with the switching transitions in CMOS circuits. We propose an optical non-invasive inspection technique for high-speed signals, based on a high sensitivity solid-state photodetector with sharp time resolution. This tool is able to probe the fast electrical waveforms propagating through ULSI circuits without electrically loading the circuit under test. The measured time resolution of 50 ps allows an equivalent analog bandwidth of about 20 GHz. From the experimental results and the luminescence characterization of single transistors, we propose a SPICE model able to foresee the photoemission in complex ULSI circuits, down to transistor level. The optical testing equipment and the SPICE modeling are valuable tools for simulation, characterization and testing of fast ULSI circuits.     

Extension of impact-ionization multiplication coefficientmeasurements to high electric fields in advanced Si BJT's

Measurements of the impact-ionization multiplication coefficient M-1 in advanced Si BJTs up to values in excess of 10 (corresponding to a peak electric field at the base-collector junction of about 9×10⁵ V/cm) are presented. The intrinsic limitations affecting M-1 measurements at high electric fields are discussed. In particular, the fundamental role played by the negative base current and the parasitic base resistance in determining instabilities during M-1 measurements is pointed out. An accurate theoretical prediction of the M-1 coefficient on collector-base voltages close to BV_CBO requires that the contribution of holes to impact ionization be properly accounted for     

Comparative parametric method 5 (PM5) study of trans-stilbene

In this work we report a comparative Austin method 1 (AM1), parametric method 3 (PM3), and parametric method 5 (PM5) studies for trans-stilbene in its ground, excited (singlet and triplet), and ionic (positive and negative polarons and bipolarons) states. We evaluated the accuracy of the recently developed PM5 method. PM5 and AM1 predict a non-planar ground and singlet states for trans-stilbene, while PM3 predicts planar ones, which is in agreement with the available experimental data. In general the PM3 and PM5 bond lengths are superior to AM1 while AM1 bond angles are superior to PM3 and PM5 when compared with available experimental data. The PM5 underestimates the cis–trans isomerization energy and and it is not a quite reliable method for the calculation of relative IP values. The presumed PM5 superior performance against AM1 and PM3 was not observed for the stilbene structures.     

Simple and facile approach to synthesize magnetite nanoparticles and assessment of their effects on blood cells

In this paper, a very simple and facile approach for the large scale synthesis of uniform and size-controllable single-domain magnetite nanoparticles is reported. These magnetite nanoparticles were synthesized via thermal decomposition of a ferric nitrate/ethylene glycol solution. The structural and morphological properties of the synthesized nanoparticles were carefully studied. Nearly spherical nanoparticles with inverted spinel structure and average particle and crystallite sizes smaller than 20 nm were obtained. The magnetic measurements revealed that magnetite nanoparticles have a magnetic saturation value near that of the bulk magnetite. The erythrocyte cytotoxicity assays showed no hemolytic potential of the samples containing magnetite nanoparticles, indicating no cytotoxic activity on human erythrocytes, which makes these interesting for biotechnological applications.