bluuebunny/crossref_metadata_2025 huggingface dataset:
Ignition of acetaldehyde‐air and acetaldehyde‐oxygen mixtures
Authors: White A Greville , Joses Elwyn
Published: July 2007

In view of the dangers said to attend the use of acetaldehyde in industrial processes, the sensitiveness to ignition of acetaldehyde vapour in admixture with air or oxygen was investigated. In the first series of experiments, case of ignition was measured by the minimum temperature at which spontaneous ignition occurred on admitting the gas mixture into a glass or metal‐lined tube kept at a specific temperature. This being a common method of determining ignition temperatures, the results could be compared with published data on other inflmmable gases and vapours. The experiment was carried out with mixtures of acetaldehyde and air or oxygen distributed over the range of maximum sensitiveness in each case. The most sensitive mixtures of acetaldehyde with air were those containing 30–60% of acetaldehyde, the lowest ignition temperature recorded being 176deg; c. in an aluminium tube; the most sensitive mixtures with oxygen contained 60–80°, of acetaldehyde, the minimum ignition temperature being 105° c. in glass or aluminium tubes. The results thus show that acetaldehyde is among the most dangerous of industrial solvents in respect of ignition by hot surfaces.

In the second series of experiments, case of ignition was measured by the minimum current in the primary circuit of an induction coil which, on interruption, would produce between standard electrodes sparks which were capable of igniting the gas mixture. This being an arbitrary test, comparative tests with other explosive gases and vapours were also included. The most sensitive mixture of acetaldehyde and air in this test contained approximately 8%, of acetaldehyde. Compared with other inflammable gases and vapours, acetaldehyde did not appear unduly sensitive to ignition by a transient source of heat of this nature.

These experiments indicate that the liability of acetaldehyde mixtures to accidental explosion in industrial operations is more likely to be due to a low ignition temperature than to exceptional sensitiveness to fugitive sources of heat such as electrical or frictional sparks. The formation of peracetic acid during the pre‐ignition oxidation of acetaldehyde could account for a number of the phenomena observed, and the explosive decomposition of peracetic acid round 110° c. may be responsible for the exceptionally low ignition temperatures of certain acetaldehyde—oxygen mixtures.
α‐monostearin and sodium stear‐ate as emulsifying agents. II. size distributions
Authors: Jellinek H. H. C. , Anson H. A.
Published: July 2007

Size distributions have been, determined on emulsions containing α‐monostearin in water‐white‐oil and sodium stearate in water at definite time intervals. The stability of the emulsions was found, to depends on the concentration of the emulsifying agents and also on the mode of preparation of the emulsions. A homogenized emulsion was shown to be very much more stable than unhomogenized emulsions. The relationship between average diameters and specific areas with time has been found to be approximately linear. Inhomogeneitics and stability factors have been evaluated for these emulsions. A mathematical analysis of the distribution curves has been carried out.
A new method for the estimation of silicon in silicon tetrachloride
Authors: Emblem H. G. , Davy V. P.
Published: July 2007

A new method has been devised for the estimation of silicon in silicon tetrachloride. It is based on a quantitative esterification with absolute ethyl alcohol, the silicon content of the resulting ester being estimated.
The volume flow of asphalt
Authors: Reiner M. , Rigden P. J. , Thrower E. N.
Published: July 2007

Measurements of the change in the dimensions of consolidated specimens of a mixture of bitumen and mineral filler under tension have shown that in addition to undergoing viscous flow the material progressively increases in volume. Both the shear and the volume‐flow have a viscous (permanent) and elastic (recoverable) component. A viscous Poisson ratio (σr) and a deformational Poisson ratio (σd) have been calculated; for the particular asphalt σc had a value of 0·085, and σd was nearly constant at a value of 0·175. Details are given of the method of calculating the viscous and the elastic shear deformation, and the viscous and elastic volume deformation.
Removal of oxygen from commercial cylinder‐hydrogen by means of palladized asbestos
Authors: Owen L. W.
Published: July 2007

The efficiency of palladized asbestos in continuously removing oxgyen from a steady stream of cylinder hydrogen is investigated. Moisture produced from the reaction magnified image which is catalysed by the palladium catalyst, is absorbed and weighed: the results obtained at various temperatures are used to find out how far the catalyst can bring the reaction to completion.

It is shown that the total oxygen present can also be estimated by this method.
An acid process for the production of chromic anhydride from chromite ore
Authors: Clay J. L. , Pearse J. F. , Trethewey D. H.
Published: July 2007

An acid process for the production of chromic anhydride from chromite ore has been developed on a pilot‐plant scale. The process, a modification of that proposed by Gresford and Wylie, was operated for six months to examine operating conditions and to determine data for design purposes. It was found to operate satisfactorily with both high‐ and low‐grade chromite ores and is suitable for large‐scale production of chromic anhydride.
The absorption of carbon dioxide by liquid drops
Authors: Dixon B. E. , Russell A. A. W.
Published: July 2007

The process of absorption of pure carbon dioxide by individual drops of water has been studied. It has been shown that, contrary to the assumption of previous workers, the rate of gas absorption of a drop during the period of formation may be very high, especially when the time of formation is short. This is due to the turbulence produced within the drop by the injection of the supply jet, which reduces the resistance to diffusion at the surface of the drop. The absorption coefficient of drops during formation has been shown to be inversely proportional to a function of the time of formation, and directly proportional to the ‘degree of turbulence,’ a concept which can be expressed in terms of orifice dimensions. The influence of the ‘degree of turbulence’ on the magnitude of the overall absorption coeficients used in chemical engineering computations is discussed.
The chlorination of ethylene and propylene. II. The chlorination of propylene
Authors: Galitzenstein E. , Woolf C.
Published: July 2007

The work on the chlorination at ordinary temperatures of the lower olefines in the liquid phase, and in the presence of ferric chloride and antimony trichloride as catalysts, has been continued, and the reactions of propylene have been studied.

As with ethylene, the main reaction was that of addition at the double bond, but larger proportions of substituted by‐products were formed than with ethylene. Thus the chief product was 1 : 2‐dichloropropane (propylene dichloride). Of the five possible trichloropropanes, the 1:2: 3‐compound was predominant, but the 1:1:2‐ and 1:2: 2‐trichloropropanes were also present.
The gravimetric determination of solids in steam condensate
Authors: Rayner J. E. , Logie D.
Published: July 2007

An apparatus has been developed for the gravimetric determination of solids in steam by the continuous evaporation of large samples of condensate in a dust‐free atmosphere. A high rate of evaporation is achieved without actual boiling, perfect evenness of operation being made possible by frequent small increments of sample. The apparatus is completely automatic and trouble‐free and shuts itself down in the event of electrical breakdown, or at the completion of the evaporation of the sample. This is made possible by the use of an electronic control unit.
An improved method for the estimation of combined fucose in seaweeds
Authors: Black W. A. P. , Cornhill W. J. , Dewar E. T. , Percival E. G. V. , Ross A. G.
Published: July 2007

An improved method for the estimation of combined fucose in ground seaweed samples is described. The oxidation of the fucose liberated on hydrolysis is conducted with periodate at a controlled pH, and the acctaldehyde liberated is estimated colorimetrically.
The chlorination of α‐chloroethylbenzene. I
Authors: Galitzenstein E. , Woolf C.
Published: July 2007

The action of various catalysts in the chlorination of α‐chloro‐ethylbenzene has been studied. Although the use of ferric chloride, antimony pentachloride and titanic chloride leads to decomposition with the evolution of hydrogen chloride, nuclear substitution takes place readily in the presence of stannic chloride. Iodine also has been found to be a very powerful and efficient catalyst, 0.25% being sufficient for the chlorination at room temperature. A surprising feature of the iodine‐catalysed chlorination is that part of the chlorine reacts by addition to the benzene nucleus; the pyrolysis of the chlorination product to split off hydrogen chloride, leaving normal nuclear‐chlorinated benzene derivatives, has also been investigated.
Sodium nitrite as an inhibitor against the attack of sea‐water on steel. III. Inhibitor in sea‐water/distilled water mixtures
Authors: Hoar T. P.
Published: July 2007

The corrosion of mild steel by sea‐water/distilled water mixtures at 25° or 60° c. can be completely inhibited by the presence of 3 percentage (w/v) of sodium nitrite greater than 1,5 of the sea‐water percentage (v/v). Similar sodium nitrite additions inhibit the corrosion of white metal by such waters and decrease the corrosion of copper (especially at 60°c. indicate they have no appreciable influence on the corrosion of brass at 25° c. Corrosion‐potential measurements at 25°c. indicate that nitrite is an anodic inhibitor. These and other results suggest that its main action is the oxidation of ferrous compounds to ferric, stannous to stannic, and cuprous to cupric, with a concomitant rise in pH, so that the very sparingly soluble higher oxides or hydrous oxides arc readily precipitated at anodic places and stifle corrosion.
The control of foaming. II. The breakdown mechanisms and volume of dynamic foams
Authors: Pattle R. E.
Published: July 2007

The mechanisms controlling the volume of foam formed by air bubbling continously through a liquid have been studied. Examples are given in which one—coalescence of bubbles within the foam— or another—bursting of bubblos at the top of the foam—predominates. The effect of alcohols in enhancing foaming, as well as in destroying foam is noted. The effect of the gm flow rate on foam volume has bed investigated and is found to differs from liquid to liquid. No simple relation between the two exists In the present state of our knowledge the foam volume under‐& given circumstances an be found only by experiment.
Electrochemical behaviour of paint films in sea‐water: A suggested mechanism
Authors: Crennell J. T.
Published: July 2007

The cathodic character of painted or otherwise partially screened steel in sea‐water is explained by the retention behind the pint‐film of the products of reaction of local corrosion couples. Local anodes behind the film will be suppressed by accumulation of ferrous ions. Alkalinity produced at local cathodes renders the steel passive and so encourages passage of further current in the same direction.

Experiments are described showing that an iron electrode transferred from neutral to alkaline salt solution becomes temporarily anodic, then quickly becomes cathodic as passivity develops.
The influence of solid properties on heat transfer from a fluidized solid medium
Authors: Campbell J. R. , Rumford F.
Published: July 2007

A range of five solids, of widely‐varying physical properties, were fluidized, as powders, by 3 heated air stream. Rates of heat transfer to a cooling coil increased in the fluidized media were measured. It is shown the hear‐transfer coefficients obtained are relatively independent of the solid conductivities, and appear to vary as the product of (surface per unit volume of the fluidized solid) and (conductivity of static powdered material). The results are compared with those published recently by other workers.
Flow through whirling tubes
Authors: Zychlin H. , Storrow J. Anderson
Published: July 2007

In various experiments in these laboratories it has become necessary to consider the effect on the energy dissipated in friction of a force acting normally to the direction of the flow‐path of a liquid. It appeared that such a case was analogous to that of a liquid constrained to flow in a coiled tube, wherein the energy dissipation is higher than in a straight tube of the same length and bore; and furthermore in the curved path a type of streamline motion persists to Reynolds' numbers which arc far greater than the lower limit of turbulence in a straight tube. The experiments described were carried out to test this analogy.
MCI‐186 prevents brain tissue from neuronal damage in cerebral infarction through the activation of intracellular signaling
Authors: Niyaz Madinyet , Numakawa Tadahiro , Matsuki Yoshinori , Kumamaru Emi , Adachi Naoki , Kitazawa Hiromi , Kunugi Hiroshi , Kudo Motoshige
Published: July 2007

The mechanism by which MCI‐186 (3‐methyl‐1‐phenyl‐2‐prazolin‐5‐one) exerts protective effects during cerebral infarction, other than its function as a radical scavenger, has not been fully elucidated. Here, we found that MCI‐186 stimulates intracellular survival signaling in vivo and in vitro. In a rat infarction model, the infarct area was significantly smaller and the degree of edema was reduced in MCI‐186‐treated animals. In the MCI‐186‐treated rats, the number of single stranded (ss) DNA‐positive damaged cells in the peri‐infarct area was decreased compared with the control, suggesting that MCI‐186 protects cerebral tissues from cell damage. To clarify the mechanisms underlying the effect of MCI‐186, we also examined the survival‐promoting effect of this agent on cultured cortical neurons. In this in vitro system, MCI‐186 blocked serum‐free induced neuronal cell death. Interestingly, an increase in the activation of both Akt (a component of the PI3 kinase pathway) and ERK (a component of the MAP kinase pathway) was observed in the cortical cultures after MCI‐186 exposure. Furthermore, the MCI‐186‐dependent survival effect in vitro was blocked by U0126, an MEK (an upstream of ERK) inhibitor, and also by LY294002, a PI3 kinase inhibitor. We also observed similar increases in the activation of Akt and ERK in the in vivo model, further suggesting that the antiapoptotic role of MCI‐186 is mediated via the PI3 kinase and MAP kinase signaling pathways. We therefore conclude that, in addition to its role as a free radical scavenger, MCI‐186 functions as an antiapoptotic factor by enhancing intracellular survival signaling. © 2007 Wiley‐Liss, Inc.
Cerebral vascular accumulation of Dutch‐type Aβ42, but not wild‐type Aβ42, in hereditary cerebral hemorrhage with amyloidosis, Dutch type
Authors: Nishitsuji Kazuchika , Tomiyama Takami , Ishibashi Kenichi , Kametani Fuyuki , Ozawa Kazuharu , Okada Ryota , Maat‐Schieman Marion L. , Roos Raymund A.C. , Iwai Kazuhiro , Mori Hiroshi
Published: July 2007

Hereditary cerebral hemorrhage with amyloidosis, Dutch type (HCHWA‐D), is an autosomal dominant disorder caused by the Dutch mutation (E693Q) in the β‐amyloid precursor protein. This mutation produces an aberrant amyloid β (Aβ) species (AβE22Q) and causes severe meningocortical vascular Aβ deposition. We analyzed the Aβ composition of the vascular amyloid in the brains of HCHWA‐D patients. Immunohistochemistry demonstrated that the vascular amyloid contained both Aβ40 and Aβ42, with a high Aβ40/Aβ42 ratio. In Western blotting of cerebral microvessel fractions isolated from the brains, both wild‐type and Dutch‐type Aβ40 were observed as major species. Reverse‐phase HPLC‐mass spectrometric analysis of the fractions revealed both wild‐type and Dutch‐type Aβ38 as the other main components of the vascular amyloid. Moreover, we detected peaks corresponding to Dutch‐type Aβ42 but not to wild‐type Aβ42. These results suggest a pathogenic role for the mutant Aβ42 in addition to the mutant Aβ40 in the cerebral amyloid angiopathy of HCHWA‐D. © 2007 Wiley‐Liss, Inc.
Dorsomedial hypothalamic nucleus neurons integrate important peripheral feeding‐related signals in rats
Authors: Zhu Jing‐Ning , Guo Chun‐Li , Li Hong‐Zhao , Wang Jian‐Jun
Published: July 2007

Several studies have implicated the dorsomedial hypothalamic nucleus (DMN) in regulation of feeding behavior and body weight, but clear mechanisms by which it controls food intake are not well understood. We report the results of the present study, which showed that the DMN receives important peripheral short‐ and long‐term feeding‐related afferent signals, including gastric vagal, glycemia, and cholecystokinin (CCK) inputs, as well as from leptin, an adipostatic signal that forcefully inhibits food intake and increases metabolic rate. Among the 279 DMN neurons recorded, 173 (62.0%) responded to stimulation of gastric vagal nerves. Also, of the 123 DMN neurons responsive to gastric vagal stimulation that were tested with the administration of intravenous glucose, 75 (61.0%) were identified as being glycemia sensitive. Moreover, it is noteworthy that of the 23 DMN neurons that responded to both gastric vagal and intravenous glucose stimulation, most (19 of 23, 82.6%) were sensitive to circulating leptin, and some neurons (n= 7) were also responsive to systemic CCK, suggesting that gastric vagal, glycemic, CCK, and leptin inputs converge on single DMN neurons. Furthermore, synergistic interactions between leptin and glucose on single DMN neurons were observed (n= 6). These results demonstrate that those important peripheral feeding‐related gastric vagal, glycemic, CCK and leptin signals not only reach the DMN but also interact on single DMN neurons, suggesting that the DMN may not just function as a relay station, but independently integrate the short‐term and long‐term feeding‐associated information and actively participate in the direct regulation of feeding behavior. © 2007 Wiley‐Liss, Inc.
The conflict‐positive organization: it depends upon us
Authors: Tjosvold Dean
Published: July 2007

Although still widely assumed to be disruptive, conflict, when managed appropriately, has been found to make teamwork within and between organizations effective. However, organizational members often have competitive relationships and orientations to dealing with conflict that lead to conflict avoidance and escalation, approaches that sabotage decision‐making and relational bonds. Conflict researchers have contributed to the bad reputation of conflict by confounding conflict and competition and suggesting that the kind of conflict, rather than its management, determines its outcomes. Studies in the West and East indicate that by developing cooperative relationships and the skills to discuss diverse views open‐mindedly, organizations can empower managers and employees to use conflict to probe problems, create innovative solutions, learn from their experience, and enliven their relationships. Copyright © 2007 John Wiley & Sons, Ltd.
The virtue and vice of workplace conflict: food for (pessimistic) thought
Authors: De Dreu Carsten K.W.
Published: July 2007

Many authors, myself included, have suggested that workplace conflict may be beneficial to the organization. I argue that the support for this conclusion is rather weak. A selective and necessarily limited review of the literature shows that: (1) the positive functions of conflict are found only under an exceedingly narrow set of circumstances, (2) the conclusion that (particular forms of) conflict and conflict management has positive functions can be criticized on methodological grounds, (3) even under favorable circumstances a number of serious negative functions can be identified as well, (4) negative functions easily outweigh positive functions, prohibiting the emergence of ‘positive workplace conflict’ (where conflict has predominantly positive consequences), and (5) organizations need cooperative conflict management not because it brings positive conflict, but because it prevents workplace conflict to hurt too much. Copyright © 2007 John Wiley & Sons, Ltd.
Development and validation of an HPLC confirmatory method for the determination of seven tetracycline antibiotics residues in milk according to the European Union Decision 2002/657/EC
Authors: Samanidou Victoria F. , Nikolaidou Konstantina I. , Papadoyannis Ioannis N.
Published: July 2007

An HPLC method with diode‐array detection, at 355 nm, was developed and validated for the determination of seven tetracyclines (TCs) in milk: minocycline (MNC), TC, oxytetracycline (OTC), methacycline (MTC), demeclocycline (DMC), chlortetracycline (CTC), and doxycycline (DC). Oxalate buffer (pH 4) was used with 20% TCA as a deproteinization agent for the extraction of analytes from milk followed by SPE. The separation was achieved on an Inertsil ODS‐3, 5 μm, 250×4 mm2 analytical column at ambient temperature. The mobile phase, a mixture of A: 0.01 M oxalic acid and B: CH3CN, was delivered using a gradient program. The procedure was validated according to the European Union decision 2002/657/EC determining selectivity, stability, decision limit, detection capability, accuracy, and precision. Mean recoveries of TCs from spiked milk samples (50, 100, and 200 ng/g) were 93.8–100.9% for MNC, 96.8–103.7% for OTC, 96.3–101.8% for TC, 99.4–107.2% for DMC, 99.4–102.9% for CTC, 96.3–102.7% for MTC, and 94.6–102.1% for DC. All RSD values were lower than 8.5%. The decision limits CCa calculated by spiking 20 blank milk samples at MRL (100 μg/kg) ranged from 101.25 to 105.84 μg/kg, while detection capability CCb from 103.94 to 108.88 μg/kg.
Analysis of coupled anisotropic dielectric waveguides using the frequency domain finite‐difference method
Authors: Sobrinho Carlos Leǒnidas da Silva Souza , Giarola Attilio José
Published: July 2007

A rigorous general and versatile finite‐difference formulation for the analysis of the propagation characteristics in structures, having the dielectric waveguide as the basic element, is presented here. In this formulation, the finite‐difference method is used in the numerical solution of the scalar wave equation, written in terms of the transverse components of the magnetic field. As a result, a conventional eigenvalue problem is obtained without the presence of spurious modes (present in previous formulations), due to the implicit inclusion of the divergence of the magnetic field equal to zero. The general case of biaxial anisotropic dielectrics is considered, with the refractive index profile varying arbitrarily in the waveguide cross section. Dispersion characteristics for isolated and parallel coupled dielectric waveguides are calculated. The theoretical development was then used to solve particular problems and the results agree with those available from other methods. Results were obtained for a variety of waveguide structures of much interest, particularly for the development of integrated optics. © 1994 John Wiley & Sons. Inc.
Software verification effort at the MIMICAD center for microstrip passive components
Authors: Wu Doris I. , Furlow Robert J.
Published: July 2007

A software verification effort to verify the accuracy of the simulation program developed by the Center for Microwave/Millimeter‐Wave Computer‐Aided Design (MIMICAD) is described. A set of single‐layer microstrip structures selected by the MIMICAD sponsors were fabricated on GaAs substrates for testing purposes. Ranging from an interdigitated capacitor to radial stubs to a section of meander line, these test structures are components commonly used in MMIC designs. Round‐robin measurements of the test structures were carried out among the MIMICAD sponsors to assess measurement consistency. Comparisons between the measured and simulated results as well as the effect of discretization in the simulation process are discussed.
Compact 900‐MHz hairpin‐line filters using high dielectric constant microstrip line
Authors: Pramanick Protap
Published: July 2007

Several miniature bandpass filters have been developed by accurate modeling of experimental and computer‐generated coupling data of hairpin‐line microstrip line resonators on high dielectric constant (εr= 80 and 90) substrate. The materials are temperature stable and of high quality factor. The experimental results show excellent filter shapes and some novelty of the design approach. Besides the experimental results, this article also presents the curves and semiempirical models for the coupling coefficients between hairpin‐line resonators for two different dielectric materials and thicknesses. The method and the results will be useful in realizing compact planar filters for cellular radio, global positioning systems and superconducting microstrip filters.
Interpolation modeling of S‐parameter data bases for use in Monte Carlo simulations
Authors: Campbell Lowell L. , Purviance John E.
Published: July 2007

A statistical interpolation technique is presented for modeling S‐parameter measurements for use in statistical analysis and design of circuits. This is accomplished by interpolating among the measurements in an S‐parameter data base in a statistically valid manner.
A cad method applied to the development of microwave oscillators
Authors: Roth Bernd , Heitbrink Axel , Beyer Adalbert
Published: July 2007

In this article, a method is proposed that allows the prediction of characteristic parameters of integrated microwave oscillators, i.e., operating frequency and distribution of the output power due to harmonic frequencies. This method combines rigorous field theoretical analysis of the linear environment with the “harmonic balance” approach. Relations between these areas are shown and discussed by means of numerical and experimental results. © 1994 John Wiley & Sons, Inc.
Quasi‐TEM analysis of reciprocal/nonreciprocal planar lines with polygonal cross‐section conductors
Authors: Plaza Gonzalo , Mesa Francisco , Horno Manuel
Published: July 2007

Multilayered multiconductor transmission lines with polygonal cross‐section‐perfect conductors are analyzed under a quasi‐TEM approach. According to a model previously proposed by the authors, each polygonal cross‐section conductor is modeled as a set of zero‐thickness strips. The substrates can be lossy, and present possible gyromagnetic (longitudinal magnetization) characteristics as well as dielectric anisotropic properties. The method of moments of Galerkin is applied in the spectral domain to analyze the model structure. Special attention has been paid to the fast and accurate computation of spectral integrals. Thus, the possible symmetries of the Galerkin matrix are emphasized and recurrence formulas to compute the tail integrals have been developed. © 1994 John Wiley & Sons, Inc.
A CAD model for microstrips on r‐cut sapphire substrates
Authors: Vendik Irina B. , Vendik Orest G. , Gevorgian Spartak S. , Sitnikova Margarita F. , Olsson Eva
Published: July 2007

Simple and correct formulas are derived for calculation of an effective isotropic dielectric constant, which characterizes the wave propagation in microstrip lines on anisotropic substrates made of r‐cut sapphire crystals. The r‐plane is extensively used for epitaxial growth of high‐Tc superconductor YBa2Cu3O7 films as applied to microwave integrated circuits. In contradistinction to previous models developed for z‐cut sapphire, the nondiagonal dielectric permittivity tensor of r‐cut sapphire is used. The effective dielectric constant of a microstrip line on r‐cut sapphire substrate is found as a function of the strip‐line geometry and the orientation of the crystallographic axes with respect to the symmetry plane of the microstrip line. © 1994 John Wiley & Sons, Inc.
Using a microstrip bandpass filter to compare different circuit analysis techniques
Authors: Swanson Daniel G.
Published: July 2007

A 22.5‐GHz microstrip bandpass filter is analyzed using three different circuit analysis techniques. Circuit theory modeling fails to provide an accurate prediction when compared to measured data. But a hybrid analysis, which uses electromagnetic field solver computations and circuit theory models, provides good agreement with measured data. A more complete field solver analysis of the filter also shows good agreement when compared to measurements. In the later two cases, the electromagnetic analysis captures the actual current distribution on the filter that circuit theory fails to predict. © 1995 John Wiley & Sons, Inc.
Harmonic‐loaded microwave power amplifiers: Nonlinear design procedure
Authors: Giannini Franco , Leuzzi Giorgio , Limiti Ernesto , Scucchia Lucio
Published: July 2007

A nonlinear design procedure for microwave power amplifiers is presented. The methodology makes use of a complete nonlinear model for the active device and an exact nonlinear analysis method. Suitable harmonic loading conditions for efficient power performance are imposed simultaneously and consistently with the analysis. The procedure is much faster than conventional repeated nonlinear analyses. © 1995 John Wiley & Sons, Inc.
Closed‐form expression for radiation resistance of a resonant rectangular microstrip patch antenna
Authors: Güney Kerim
Published: July 2007

A new, very simple curve‐fitted expression is presented for the radiation resistance of resonant rectangular microstrip antennas. It is derived from numerical results available in the literature, and is useful for the computer‐aided design (CAD) of microstrip antennas. This expression can be used for a wide range of substrate thicknesses and permittivities. The results obtained by using this expression are in conformity with those reported elsewhere. © 1995 John Wiley & Sons, Inc.
Electrical modeling of packaging discontinuities: A general methodology based on the three‐dimensional TLM concept
Authors: Boussetta Chokri , Ndagijimana Fabien , Chilo Jean , Saguet Pierre
Published: July 2007

A general methodology for modeling packages using the three‐dimensional (3D) TLM method is presented. S parameters are calculated from reflected and transmitted signals, and electrical parameters of equivalent networks are extracted. Frequency domain results (up to 30 GHz) are presented for a microstrip right‐angle bend, a cross junction, and vias. The purpose of this article is to demonstrate the possibilities of using the 3D TLM method for electrical modeling in packaging applications.
Improvement of the active load‐pull technique for the optimization of high power communication SSPAs
Authors: Nebus Jean‐Michel , Bouysse Philippe , Villotte Jean‐Pierre , Obregon Juan
Published: July 2007

This article presents recent developments in the active load‐pull technique which improve the accuracy, reliability, and efficiency of power transistor characterization. In the load‐pull system described in this article, both the active loop technique and the mismatching technique are implemented. This allows fine and accurate synthesis of load impedances anywhere on the Smith chart. The two main attractive capabilities of the proposed system are: (1) Fine and accurate characterization of highly mismatched components is made easier. This is illustrated in this article with measurement results of a 4‐W silicon bipolar transistor. (2) Load impedance areas where transistors provide their best amplification performances can be finely scanned. Therefore, data processing routines are easier, more accurate, and more efficient. This is particularly useful for the optimization of trade‐offs between power‐added efficiency and third order intermodulation in power transistor. This is demonstrated with measurement results using a 4‐W GaAs power FET.
Parameter extraction for large‐signal modeling of bipolar junction transistors
Authors: Rohringer Norbert M. , Kreuzgruber Peter
Published: July 2007

A quick and efficient parameter extraction method for Si‐bipolar junction transistors, suited for nonlinear CAD, is presented. The large‐signal parameters are extracted from S‐parameter data measured at one bias point only. The model accounts for distributed base and bond wires. A comparison of simulated and measured values of reflection and transmission coefficients and nonlinear behavior of a single transistor shows the capability of the extraction method.
Accurate large‐signal GaAs MESFET and HEMT modeling for power MMIC amplifier design
Authors: Dortu Jean‐Marc , Müller Jan‐Erik , Pirola Marco , Ghione Giovanni
Published: July 2007

This article describes, from an industrial user's point of view, how large‐signal GaAs MESFET and HEMT modeling can be done accurately and efficiently for power MMIC amplifier design. The method is based on commercially available CAD tools enhanced by in‐house software (e.g., small‐signal parameter extraction, generation of load‐pull contours). The Materka model is shown to predict accurately the large‐signal characteristics of GaAs MESFETs, but not of pseudomorphic HEMTs. For these devices, a modified Angelov model is found to be adequate. A method for determining the numerous large‐signal model parameters is presented. Model verification is achieved by comparing simulated and on‐wafer measured data like static I(V)‐characteristics, multiple bias S‐parameters, gain compression characteristics, and load‐pull contours. Results of device scaling and calculations of optimum load impedances are discussed. The close fit to the measured data proves that an excellent basis for large‐signal power MMIC design has been established.
Accurate design of compact forward‐coupled microstrip filters using an integral‐equation field solver
Authors: Zhang Dawei , Liang Guo‐Chun , Shih Chien‐Fu , Johansson Marie E. , Withers Richard S.
Published: July 2007

In this article, we present forward‐coupled microstrip filters designed using an integral‐equation‐based field solver, and fabricated in high‐temperature superconducting (HTS) thin films. Two designs were studied, one a nine‐pole bandpass filter at 900 MHz with 25‐MHz bandwidth, and the other a five‐pole bandpass filter at 2 GHz with 24‐MHz bandwidth and 10‐Ω resonator characteristic impedance. Both designs were fabricated using YBa2Cu3O7(YBCO) HTS thin films. Measurements showed excellent agreements with the simulation predictions. For the nine‐pole filter design, a measured insertion loss of 0.3 dB, and a measured return loss of 16 dB were achieved in the YBCO filter at 77 K. © 1995 John Wiley & Sons, Inc.
Dual‐band, dual‐polarized patch antennas
Authors: Piazzesi Peter , Maci Stefano , Gentili Guido Biffi
Published: July 2007

Two new configurations of patch antennas are introduced, which provide dual‐band and dual‐polarization operations. The two patches have a square and cross shape, and are printed on a single layer; the dual‐frequency and the dual‐polarization behavior is obtained by means of four narrow slots close to the edges. Excellent decoupling between the two orthogonal modes at each frequency is obtained in both configurations. Furthermore, a satisfactory performance of simultaneous matching when using a single feed point is demonstrated. Simple and accurate design formulas to predict the two resonant frequencies are derived on the basis of a physical model and tested by using a full‐wave analysis. Some prototypes have been carried out and measured.
Sensitivity analysis of a four‐pole filter
Authors: Lajoie Isabelle , Verdeyme Serge , Aubourg Michel , Guillon Pierre
Published: July 2007

Rigorous analysis of a four‐pole elliptic filter, constructed by placing two cascaded dielectric resonators operating on their first hybrid mode, is performed using the finite element method. Sensitivity analysis of the input‐output and the interresonator rectangular and cross irises is presented. Theoretical and experimental results are compared.
The efficacy of protective effects of tannic acid, gallic acid, ellagic acid, and propyl gallate against hydrogen peroxide‐induced oxidative stress and DNA damages in IMR‐90 cells
Authors: Chen Ching‐Hsein , Liu Tsan‐Zon , Chen Chin‐Hui , Wong Chung Hang , Chen Chi‐Hung , Lu Fung‐Jou , Chen Ssu Ching
Published: July 2007

There is increasing evidence that reactive oxygen species (ROS) are intimately involved in the oxidative damage of tissues for a wide variety of pulmonary diseases. Thus, it is desirable to search for chemopreventive agents that can counteract ROS‐mediated injury to the pulmonary tissues. Using a human lung fibroblast IMR‐90 cells as the experimental model, we first demonstrated that nearly 90% of intracellular ROS could be removed when H2O2‐treated cells (200 μM) simultaneously incubated with 10 μg/mL of tannic acid (TA), gallic acid (GA), ellagic acid (EA), and propyl gallate (PA). Using C11‐BODIPY581/591 as a lipid peroxidation probe, we also attested that all these compounds examined (10 μg/mL) could alleviate H2O2‐evoked lipid peroxidation phenomena. Next, we examined the protective effects of these compounds on the depletion of intracellular glutathione (iGSH) in H2O2‐treated cells using CMF‐DA probe. Interestingly, PA was demonstrated to be the only compound that could effectively protect the integrity of iGSH from being depleted by this system. Finally, the protective effects of these compounds against oxidative DNA damage were evaluated using 8‐oxoguanine formation as a marker. Our data indicated that all four compounds suppressed the formation of 8‐oxoguanine effectively. Taken together, our data suggested that TA, GA, EA, and PA can protect cells from oxidative stress.
Comparison of the relative recovery of polyphenolics in two fruit extracts from a model of degradation during digestion and metabolism
Authors: Stevenson David E. , Cooney Janine M. , Jensen Dwayne J. , Zhang Jingli , Wibisono Reginald
Published: July 2007

To simulate the effects of digestion and metabolism on the survival of different polyphenolic compounds, extracts of blueberry and apple were deglycosylated by acid hydrolysis, followed by enzymic glucuronidation under neutral conditions, yielding ∼︁5% overall recovery of polyphenolics. The major polyphenolics before and after the treatment were compared, to estimate which species are likely to be present in the intestinal lumen, undegraded and available for absorption, after consumption of the fruit. Whereas blueberry extract consisted predominantly of anthocyanins, epicatechin and caffeoyl quinate esters, the major components of the treated extract were quercetin glucuronides and (unglucuronidated) caffeoyl quinates, with only traces of anthocyanidin derivatives. In apple extract, compositional changes were less marked, but caffeoyl quinates, procyanidins and quercetin were enriched at the expense of caffeic acid, epicatechin and catechin. Hydrophobic compounds like phloretin and quercetin were extensively glucuronidated, whereas caffeic acid and caffeoyl quinate were not. These results suggest that the major polyphenolic components of a fruit are not necessarily the most important contributors to any health benefits because the polyphenolic composition in the intestinal lumen and consequently, in the circulation, may be considerably different.
Biphasic modulation of cell proliferation by sulforaphane at physiologically relevant exposure times in a human colon cancer cell line
Authors: Pappa Gerlinde , Bartsch Helmut , Gerhäuser Clarissa
Published: July 2007

Sulforaphane (SFN), a cancer chemopreventive compound derived from broccoli, is able to induce cell cycle arrest and apoptosis in various tumor cell lines. Here we show that cell growth inhibition by SFN follows a biphasic pattern: Transient exposure of 40‐16 human colon carcinoma cells for up to 6 h resulted in reversible G2/M cell cycle arrest and cytostatic growth inhibition even at elevated concentrations, whereas a minimum continuous exposure time of 12 h was necessary for SFN to irreversibly arrest cells in G2/M phase and subsequently induce apoptosis. IC50 values after 12 h of exposure followed by drug‐free recovery up to 72 h (6.4–8.1 μM) were indistinguishable from those of chronic exposure for 24 to 72 h (5.4–6.6 μM). Low concentrations of SFN caused a transient decrease in glutathione (GSH) levels followed by GSH induction, which may be related to reversible G2/M arrest and cytostatic effects. Depletion of GSH does not seem to play a role in SFN‐mediated apoptosis induction. Our data clearly contribute to a better understanding of the kinetics of antiproliferative activity of SFN.
Multijoint reflexes of the stroke arm: Neural coupling of the elbow and shoulder
Authors: Sangani Samir G. , Starsky Andrew J. , Mcguire John R. , Schmit Brian D.
Published: July 2007

The reflex torque responses of the elbow and shoulder to constant velocity angular extensions of the full comfortable range of the spastic elbow were measured in 16 people with unilateral stroke and 6 neurologically intact controls in order to identify the interjoint reflex coupling that occurs after stroke. The resulting responses showed a substantial reflex torque at the elbow and shoulder in subjects with stroke, with 12 of the 16 subjects producing adduction of the shoulder in response to passive extension of the elbow. The presence of simultaneous shoulder flexion torque with elbow flexion torque and with an identical waveform indicated an active role of biarticular elbow/shoulder flexors, such as the biceps. As the biceps muscle produces a shoulder abduction moment, shoulder adduction produced during elbow extension was thought to be associated with neural rather than biomechanical coupling. These results suggest that spasticity in people with stroke is more complex than its traditional perception as a hyperexcitable stretch reflex, and includes potent heteronymous reflex pathways. The reflex coupling observed between the shoulder and elbow should be considered in the diagnosis and clinical management of spasticity. The potential impact of this reflex on the coordination of volitional arm movements will be examined in future studies. Muscle Nerve, 2007
Managing fddi networks: The state of the standards
Authors: Jones Dr Katherine
Published: July 2007

The third in a serieson the FDDI standard, this article looksatSMT–the Fibre Distributed Data Interface Station Management–and the directions for FDDI over copper cables.
Token ring network management: Problem determination
Authors: Nilausen Jesper
Published: July 2007

In this article we will look at Problem Determination as the phase to initiate and go through when the normal Problem Management reporting mechanisms and procedures are not adequate.
Security and the Enterprise Network
Authors: Banes David
Published: July 2007

We'll offer some practical guidelines for assessing security risks that can assist network managers in devising a security strategy appropriate to their particular environments.
APPN—An Introduction
Authors: Nilausen Jesper
Published: July 2007

This first article in a series on managing APPN Networks briefly introduces a relatively new networking architecture.

Both traditional hierarchical SNA Networks and modern distributed Client/Server environments highly benefit from utilizing APPN functionality in their network configurations. APPN actually grew up in an environment which combines these two worlds: The IBM midrange computer environment based on AS/400 machines.

APPN is part of IBM SNA (Systems Network Architecture) and many abbreviations in this series of articles actually are commonly used SNA terms.
Development of a new heterojunction structure (ACJ ‐HIT) and its application to polycrystalline silicon solar cells
Authors: Tanaka Makoto , Taguchi Mikio , Takahama Tsuysohi , Sawada Toru , Kuroda Shigeru , Matsuyama Takao , Tsuda Shinya , Takeoka Akio , Nakano Shoichi , Hanafusa Hiroshi , Kuwano Yukinori
Published: July 2007

A new solar cell structure named HIT (Heterojunction with Intrinsic Thin layer) has been developed based on new artificially constructed junction (ACJ) technology. In this structure a non‐doped a‐Si thin layer was inserted between the p(a‐Si)/n(c‐Si) heterojunction, improving the output characteristics and achieving a conversion efficiency of 18.1%. This structure was applied to cast polycrystalline silicon solar cells of a practical size. A high conversion efficeincy of 13.6% was obtained with a cell size of 10 cm × 10 cm using various technologies, including hydrogen plasma passivation.
Parameter estimation and screening of solar cells
Authors: Appelbaum J. , Chait A. , Thompson D.
Published: July 2007

The aggregation (sorting) of the individual solar cells into an array is commonly based on a single operating point on the current‐voltage (I‐V) characteristic curve. an alternative approach for cell performance prediction and cell screening is provided by modelling the cell using an equivalent electrical circuit, in which the parameters involved are related to the physical phenomena in the device. These analytical models may be represented by a double exponential I‐V characteristic with seven parameters, by a double exponential model with five parameters or by a single exponential equation with four or five parameters. In this article we address issues concerning methodologies for the determination of solar cell parameters based on measured data points of the I‐V characteristic, and introduce a procedure for screening solar cells for arrays. We show that common curve‐fitting techniques, e.g. least‐squares, may produce many combinations of parameter values while maintaining a good fit between the fitted and measured I‐V characteristics of the cell. Therefore, techniques relying on curve‐fitting criteria alone cannot be used directly for cell parameterization. We propose a consistent procedure that takes into account the entire set of parameter values for a batch of cells. This procedure is based on a definition of a mean cell representing the batch, and takes into account the relative contribution of each parameter to the overall goodness of fit. the procedure is demonstrated on a batch of 50 silicon cells for Space Station Freedom.
Measuring the costs of photovoltaics in an electric utility planning framework
Authors: Awerbuch Shimon
Published: July 2007

Utility planning models evaluate alternative generating options using the revenue requirements method—an engineering‐oriented, discounted cash‐flow (DCF) methodology that has been widely used for over three decades. Discounted cash‐flow techniques were conceived in the context of active expense‐intensive technologies, such as conventional, fuel‐intensive power generation. Photovoltaic (PV) technology, by contrast, is passive and capital intensive—attributes that are similar to those of other new process technolgies, such as computer‐integrated manufacturing. Discounted cash‐flow techniques have a dismal record for correctly valuing new technologies with these attributes, in part because their benefits cannot be easily measured using tradiational accounting concepts.

This paper examines how these issues affect cost measurement in both conventional and PV‐based electricity, and presents kWh‐cost estimates for three technologies (coal, gas and PV) using risk‐adjusted approaches, which suggest that PV costs are generally equivalent to the gas/combined cycle and about twice the cost of base‐load coal (environmental externalities are ignored). Finally, the paper evaluates independent power purchases for a typical US utility and finds that in such a setting the cost of PV‐based power is comparable to the firm's published avoided costs.