Characteristics of permeation and separation of dimethyl acrylamide-methyl methacrylate random and graft copolymer membranes for a benzene/cyclohexane mixture

When a benzene/cyclohexane mixture was permeated through poly(dimethyl acrylamide-random-methyl methacrylate) (DMAA-r-MMA) and poly(dimethyl acrylamide)-graft-poly(methyl methacrylate) (DMAA-g-MMA) membranes by pervaporation, the benzene-permselectivity of the DMAA-r-MMA membrane changed from the diffusivity selectivity to the solubility selectivity with increasing DMAA content but DMAA-g-MMA membranes with a high DMAA content had the higher apparent diffusivity selectivity than the apparent solubility selectivity. Furthermore, the apparent solubility selectivity for a benzene/cyclohexane mixture between the DMAA-r-MMA membrane and the DMAA-g-MMA membrane with a high DMAA content was remarkably different. These results were attributed to the difference of structure between the copolymers. Received: 27 August 1997/Revised version: 22 October 1997/Accepted: 30 October 1997     

Good trellises for IC implementation of Viterbi decoders for linearblock codes

This paper investigates trellis structures of linear block codes for the integrated circuit (IC) implementation of Viterbi decoders capable of achieving high decoding speed while satisfying a constraint on the structural complexity of the trellis in terms of the maximum number of states at any particular depth. Only uniform sectionalizations of the code trellis diagram are considered. An upper-bound on the number of parallel and structurally identical (or isomorphic) subtrellises in a proper trellis for a code without exceeding the maximum state complexity of the minimal trellis of the code is first derived. Parallel structures of trellises with various section lengths for binary BCH and Reed-Muller (RM) codes of lengths 32 and 64 are analyzed. Next, the complexity of the IC implementation of a Viterbi decoder based on an L-section trellis diagram for a code is investigated. A structural property of a Viterbi decoder called add-compare-select (ACS)-connectivity which is related to state connectivity is introduced. This parameter affects the complexity of wire-routing (interconnections within the IC). The effect of five parameters namely: (1) effective computational complexity; (2) complexity of the ACS-circuit; (3) traceback complexity; (4) ACS-connectivity; and (5) branch complexity of a trellis diagram on the very large scale integration (VLSI) complexity of a Viterbi decoder is investigated. It is shown that an IC implementation of a Viterbi decoder based on a nonminimal trellis requires less area and is capable of operation at higher speed than one based on the minimal trellis when the commonly used ACS-array architecture is considered     

A database of frequency distributions of energy depositions in small-size targets by electrons and ions

Linear energy transfer (LET) is an average quantity, which cannot display the stochastics of the interactions of radiation tracks in the target volume. For this reason, microdosimetry distributions have been defined to overcome the LET shortcomings. In this paper, model calculations of frequency distributions for energy depositions in nanometre size targets, diameters 1-100 nm, and for a 1 μm diameter wall-less TEPC, for electrons, protons, alpha particles and carbon ions are reported. Frequency distributions for energy depositions in small-size targets with dimensions similar to those of biological molecules are useful for modelling and calculations of DNA damage. Monte Carlo track structure codes KURBUC and PITS99 were used to generate tracks of primary electrons 10 eV to 1 MeV, and ions 1 keV μm(-1) to 300 MeV μm(-1) energies. Distribution of absolute frequencies of energy depositions in volumes with diameters of 1-100 nm randomly positioned in unit density water irradiated with 1 Gy of the given radiation was obtained. Data are presented for frequency of energy depositions and microdosimetry quantities including mean lineal energy, dose mean lineal energy, frequency mean specific energy and dose mean specific energy. The modelling and calculations presented in this work are useful for characterisation of the quality of radiation beam in biophysical studies and in radiation therapy.     

Effects of liquid viscosity on inception of disturbance waves and droplets in gas–liquid annular two‐phase flow

The structure of gas–liquid two‐phase flow is investigated in order to establish a reliable criterion for the development of disturbance waves and droplets considering the effects of liquid viscosity. The structure of the gas–liquid interface and the flow rate of droplets entrained in gas are measured simultaneously at five kinematic viscosities (1.0, 3.2, 9.9, 30, 70 mm²/s). The time‐series traces of liquid film thickness measured by five holdup probes reveal that the inception of disturbance waves occurs at a liquid Reynolds number of 200 or a non‐dimensional liquid film thickness of 6.5. It is also shown that droplets are generated before the inception of disturbance waves with increasing liquid kinematic viscosity at a liquid velocity of 0.02 to 0.03 m/s. As previously published criteria for the inception of droplets are found to be unsatisfactory, a new critical condition for droplet generation balancing the interfacial shear stress $τi$ with the wave height h and surface tension σ is proposed: $τih/σ=0.025$. This relation describes the action of shear force and surface tension on wave crests, and is notably independent of liquid viscosity. © 2007 Wiley Periodicals, Inc. Heat Trans Asian Res, 36(8): 529–541, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/htj.20176     

Improvement in high temperature stability of Pd coating on Nb by Nb2C intermediate layer

Niobium subcarbide (Nb₂C) was chosen as a material for non-porous intermediate layer to improve the high temperature durability of Pd–Nb composite membranes for hydrogen separation. A layer of Nb₂C was prepared between Nb substrate and thin Pd films (100 nm), and the stability of Pd coating at elevated temperatures (573–773 K) was examined by hydrogen absorption experiments. Hydrogen permeability through the Nb₂C layer appeared to be sufficiently high, and no noticeable deterioration was observed in hydrogen absorption rate under as-prepared conditions. The degradation in coating effect of Pd at elevated temperatures was substantially mitigated by Nb₂C layer. Such improved durability was ascribed to retardation of open porosity development by Nb₂C caused as a consequence of impeded interdiffusion between Pd and Nb.     

Systemic effects and withdrawal syndrome in chronic users of corticosteroids]

Three newly found vibrational levels at energies Te(v) = 45127.88(3), 51900.40(4), and 52604.95(3) cm-1 allow the first application of resonance-enhanced multiphoton ionization for detecting the SO radical in its low-energy singlet states, a1Delta and b1Sigma+. The analysis of the spectra is based on the observation of 10 rotationally resolved bands starting from a1Delta v = 0, 6 ellipsis 11 and b1Sigma+ v = 8, covering a typical range of J = 5 ellipsis 40 or 50. Population of these SO singlet states has been achieved by two-photon dissociation of SO2 in a molecular beam environment, applying wavelengths in the 248 to 291 nm range. This paper presents an analysis of the rotational, vibrational, and electronic properties of the new levels. Reviewing earlier works on the singlet states of SO, a revised term energy scheme is provided which connects the singlet and triplet systems of the molecule. Copyright 1998 Academic Press.     

Design of new inhibitors for cdc2 kinase based on a multiple pseudosubstrate structure

New inhibitors have been designed for cdc2 kinase based on a multiple pseudosubstrate structure. The new inhibitors have three different structural components: 3,4-bis(indol-3-yl)maleimide, Ac-Cys-(Ser)-Pro-Lys-Lys-NHMe, and ethyloxy group between the two components. Inhibitory activities toward cdc2 and other protein kinases were investigated, and the compound (21) with Ac-Cys-Pro-Lys-Lys-NHMe connected with the triethylene glycol spacer exhibited the most potent inhibition with relatively high selectivity.     

Evolution of nursing at University Hospitals: depositions by nurses who worked during the seventies

This study is part of a more extensive project that proposes to recover significant aspects related to nursing care evolution from 1950s until 1990s. This study is developed through the technique of oral declaration by active and retired registered nurses, in the context of an university-hospital from S?o Paulo State. The present study emphasizes the outcomes referring to the 1970s. As result becomes evident the undertaken effort by nurses in the struggle for profession's recognition and prestige; intense and deep transformations related to nurse's new roles as leadership of nursing staff and member of medical team.     

Dunham Treatment Including Effects of the Born-Oppenheimer Breakdown for Open-Shell Diatomic Molecules in 2Sigma States

Two high-performance liquid chromatographic (HPLC) methods are described for determination of (+/-)-ethopropazine (ET) in rat plasma. After deproteination and liquid-liquid extraction, assay of (+/-)-ET was performed using either a C18 column (non-stereospecific assay) or an (alpha-R-naphthyl)ethylurea column (stereospecific assay). The UV detection was at 250 nm. Mean recovery was >85%. Both assays demonstrated excellent linear relationships between peak height ratios and plasma concentrations; quantitation limits were < or =25 ng/ml, based on 100 microl rat plasma. Accuracy and precision were <17% with both methods. Both methods were applied successfully to the measurement of ET plasma concentrations in rats given the drug intravenously.     

A case of foramen magnum meningioma in which case enhanced three-dimensional CT scan was valuable for preoperative evaluation of the surgical approach

We report a case of foramen magnum meningioma in which case enhanced three-dimensional CT scan was valuable for preoperative evaluation of the surgical approach. A 53-year-old woman had suffered from stiffness and pain in the left occipital region and numbness of the left side of the face for about 2 years before admission. She had also weakness and numbness of the left side of her body for about 2 months before admission, and dysphagia and pain in the occipital region and in the posterior region of the neck produced by straining for about 1 month before admission. Neurological examination revealed left hemiparesis, and hypalgesia and tactile hypesthesia of the left side of the body, including the face. Plain X-P was normal. Enhanced CT scan and gadolinium enhanced MRI revealed a well-enhanced mass attached to the left anterolateral part of the foramen magnum. The left occipital condyle was observed at the lateral side of the attachment part of this mass. Angiography revealed tumor feeders from the meningeal branches of the left vertebral artery and the left ascending pharyngeal artery. Enhanced three-dimensional CT scan clearly showed that the tumor was attached to the left anterolateral part of the foramen magnum, that the left occipital condyle was at the lateral side of the attachment part of this mass and that the jugular foramen and jugular tubercle were situated superolateral to the attachment part of this mass. Considering these factors, we decided that removal of the posterior part of the left occipital condyle was necessary, but removal of the left jugular tubercle was not necessary for a good operative view from the left posterior lateral direction. The tumor was totally removed successfully and good results were obtained by the transcondylar approach without removal of the jugular tubercle. Histology of the tumor revealed meningothelial meningioma. In this case, preoperative evaluation with enhanced three-dimensional CT scan was helpful for deciding the surgical approach. With enhanced three-dimensional CT scan, it is easy to judge whether removal of the posterior part of the occipital condyle and/or the jugular tubercle is necessary for a good operative view, and we can get good images revealing the relationships between the tumor and surrounding structures. Preoperative evaluation with enhanced three-dimensional CT scan is very useful especially in this kind of situation.