Design of asymmetrical RF and microwave bandpass filters by computer optimization

This paper presents an optimization-based approach to the design of asymmetrical filter structures having the maximum number of return- or insertion-loss ripples in the passband such as those based upon Chebyshev function prototypes. The proposed approach. has the following advantages over the general purpose optimization techniques adopted previously such as: less frequency sampling is required, optimization is carried out with respect to the Chebyshev (or minimax) criterion, the problem of local minima does not arise, and optimization is usually only required for the passband. When implemented around an accurate circuit simulation, the method can be used to include all the effects of discontinuities, junctions, fringing, etc. to reduce the amount of tuning required in the final filter. The design of asymmetrical ridged-waveguide bandpass filters is considered as an example. Measurements on a fabricated filter confirm the accuracy of the design procedure.

Ultrasound-assisted green synthesis of nanocrystalline ZnO in the ionic liquid [hmim][NTf2]

For the first time, zinc oxide nanoparticles have been synthesized by the sonochemical method in an ionic liquid, 1-hexyl-3-methylimidazolium his (trifluoromethylsulfonyl) imide, liquid [hmim][NTf2] as a solvent. The morphology and structure of ZnO nanoparticles have been characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). A possible mechanism is proposed to explain the formation of ZnO nanostructures. (C) 2008 Elsevier B.V. All rights reserved.

Improved preparations of ionic liquids using microwave irradiation

Controlled, multimode microwave irradiation has been employed in a generic solvent-free process to prepare a wide range of ionic liquids based on nitrogen-containing heterocycles. The developed method offers a flexible, small to large-scale approach to prepare ionic liquids, in either sealed or open vessels, in a faster and greener process than any previously described.

Assisted Diagnosis of Cervical Intraepithelial Neoplasia (CIN)

This paper introduces an automated computer- assisted system for the diagnosis of cervical intraepithelial neoplasia (CIN) using ultra-large cervical histological digital slides. The system contains two parts: the segmentation of squamous epithelium and the diagnosis of CIN. For the segmentation, to reduce processing time, a multiresolution method is developed. The squamous epithelium layer is first segmented at a low (2X) resolution. The boundaries are further fine tuned at a higher (20X) resolution. The block-based segmentation method uses robust texture feature vectors in combination with support vector machines (SVMs) to perform classification. Medical rules are finally applied. In testing, segmentation using 31 digital slides achieves 94.25% accuracy. For the diagnosis of CIN, changes in nuclei structure and morphology along lines perpendicular to the main axis of the squamous epithelium are quantified and classified. Using multi-category SVM, perpendicular lines are classified into Normal, CIN I, CIN II, and CIN III. The robustness of the system in term of regional diagnosis is measured against pathologists' diagnoses and inter-observer variability between two pathologists is considered. Initial results suggest that the system has potential as a tool both to assist in pathologists' diagnoses, and in training.

Dielectric constant characterization using a numerical method for the microstrip ring resonator

A new method of dielectric-constant measurement is developed. The dielectric constant epsilon(r) RF/microwave substrate is extracted by combining the microstrip ring resonator measurement with Ansoft HFSS electromagnetic simulation software. The developed method has two advantages: (i) characterization of dielectric constant versus multiple frequency points, and (ii) compatibility with electronics design automation (EDA) software tools. This characterization method can reduce the design cycle of microwave circuits and devices. (C) 2004 Wiley Periodicals, Inc.

Molecular-assisted immunohistochemical optimization

Immunohistochemistry (IHC) is an essential tool in diagnostic surgical pathology, allowing analysis of protein subcellular localization The use of IHC by different laboratories has lead to inconsistencies in published literature for several antibodies, due to either interpretative (inter-observer venation) or technical reasons These disparities have major implications in both clinical and research settings In this study, we report our experience conducting an IHC optimization of antibodies against five proteins previously identified by proteomic analysis to be breast cancer biomarkers, namely 6PGL (PGLS), CAZ2 (CAPZA2), PA2G4 (EBP1) PSD2 and TKT Large variations in the immunolocalizations and intensities were observed when manipulating the antigen retrieval method and primary antibody incubation concentration However, the use of an independent molecular analysis method provided a clear indication in choosing the appropriate biologically and functionally relevant

Structural investigations and magnetic properties of sol-gel Ni0.5Zn0.5Fe2O4 thin films for microwave heating

Nanocrystalline Ni0.5Zn0.5Fe2O4 thin films have been synthesized with various grain sizes by a sol-gel method on polycrystalline silicon substrates. The morphology, magnetic, and microwave absorption properties of the films calcined in the 673-1073 K range were studied with x-ray diffraction, scanning electron microscopy, x-ray photoelectron spectroscopy, atomic force microscopy, vibrating sample magnetometry, and evanescent microwave microscopy. All films were uniform without microcracks. Increasing the calcination temperature from 873 to 1073 K and time from 1 to 3 h resulted in an increase of the grain size from 12 to 27 nm. The saturation and remnant magnetization increased with increasing the grain size, while the coercivity demonstrated a maximum near a critical grain size of 21 nm due to the transition from monodomain to multidomain behavior. The complex permittivity of the Ni-Zn ferrite films was measured in the frequency range of 2-15 GHz. The heating behavior was studied in a multimode microwave cavity at 2.4 GHz. The highest microwave heating rate in the temperature range of 315-355 K was observed in the film close to the critical grain size.

Method for the in situ preparation of a single layer of zeolite Beta crystals on a molybdenum substrate for microreactor applications

A method for the hydrothermal synthesis of a single layer of zeolite Beta crystals on a molybdenum substrate for microreactor applications has been developed. Before the hydrothermal synthesis, the surface of the substrate was modified by an etching procedure that increases the roughness at the nanoscale level without completely eliminating the surface lay structure. Then, thin films of Al2O3 (170 nm) and TiO2 (50 nm) were successively deposited by atomic layer deposition (ALD) on the substrate. The internal Al2O3 film protects the Mo substrate from oxidation up to 550 degrees C in an oxidative environment. The high wettability of the external TiO2 film after UV irradiation increases zeolite nucleation on its surface. The role of the metal precursor (TiCl4 vs TiI4), deposition temperature (300 vs 500 degrees C), and film thickness (50 vs 100 nm) was investigated to obtain titania films with the slowest decay in the superhydrophilic behavior after UV irradiation. Zeolite Beta coatings with a Si/Al ratio of 23 were grown at 140 degrees C for 48 It. After ion exchange with a 10(-4) M cobalt acetate solution, the activity of the coatings was determined in the ammoxidation of ethylene to acetonitrile in a microstructured reactor. A maximum reaction rate of 220 mu mol C2H3N g(-1) s(-1) was obtained at 500 degrees C, with 42% carbon selectivity to acetonitrile. (C) 2007 Elsevier Inc. All rights reserved.

F. E.-assisted design of the eaves bracket of a cold-formed steel portal frame

Non-linear large-displacement elasto-plastic finite element analyses are used to propose design recommendations for the eaves bracket of a cold-formed steel portal frame. Owing to the thinness of the sheet steel used for the brackets, such a structural design problem is not trivial as the brackets need to be designed against failure through buckling; without availability of the finite element method, expensive laboratory testing would therefore be required. In this paper, the finite element method is firstly used to predict the plastic moment capacity of the eaves bracket. Parametric studies are then used to propose design recommendations for the eaves bracket against two potential buckling modes of failure:

A more direct way to make catalysts: one-pot ligand-assisted aerobic stripping and electrodeposition of copper on graphite

Electrodeposition of metals onto conductive supports such as graphite potentially provides a lower-waste method to form heterogeneous catalysts than the standard methods such as wet impregnation. Copper electrodeposition onto pressed graphite disc electrodes was investigated from aqueous CuSO4-ethylenediamine solutions by chronoamperometry with scanning electron microscopy used to ascertain the particle sizes obtained by this method. The particle size was studied as a function of pH, CuSO4-ethylenediamine concentration, and electrodeposition time. It was observed that decreasing the pH, copper-ethylenediamine concentration and time each decreased the size of the copper particles observed, with the smallest obtained being around 5-20 nm. Furthermore, electroless aerobic oxidation of copper metal in the presence of ethylenediamine was successfully coupled with the electrodeposition in the same vessel. In this way, deposition was achieved sequentially on up to twenty different graphite discs using the same ethylenediamine solution, demonstrating the recyclability of the ligand. The materials thus prepared were shown to be catalytically active for the mineralisation of phenol by hydrogen peroxide. Overall, the results provide a proof-of-principle that by making use of aerobic oxidation coupled with electrochemical deposition, elemental base metals can be used directly as starting materials to form heterogeneous catalysts without the need to use metal salts as catalyst precursors.

Estimation of the surface area and volume of the retinal capillary basement membrane using the stereologic method of vertical sections

The modern stereologic method of vertical sections was applied to the retina as a means of generating unbiased estimates of three-dimensional structure. The method is illustrated with real data on the volume and surface area of the capillary basement membrane from the central retina of the rat. Novel methods of estimating the volume of retina sampled and of creating accurate vertical sections are described. The advantages of using stereologic methods to generate quantitative information on the three-dimensional structure of the retina are discussed and compared to those of previous quantitative methods that provide data on two-dimensional structure only.

Mask assisted fabrication of nanoislands of BiFeO3 by ion beam milling

We report on a low-damage method for direct and rapid fabrication of arrays of epitaxial BiFeO3(BFO) nanoislands. An array of aluminium dots is evaporated through a stencil mask on top of an epitaxial BiFeO3 thin film. Low energy focused ion beam milling of an area several microns wide containing the array-covered film leads to removal of the bismuth ferrite in between the aluminium-masked dots. By chemical etching of the remaining aluminium, nanoscale epitaxial bismuth ferrite islands with diameter ∼250 nm were obtained. Piezoresponse force microscopy showed that as-fabricated structures exhibited good piezoelectric and ferroelectric properties, with polarization state retention of several days.

Taguchi optimisation approach for production of activated carbon from phosphoric acid impregnated palm kernel shell by microwave heating

Taguchi method was applied to investigate the optimal operating conditions in the preparation of activated carbon using palm kernel shell with quadruple control factors: irradiation time, microwave power, concentration of phosphoric acid as impregnation substance and impregnation ratio between acid and palm kernel shell. The best combination of the control factors as obtained by applying Taguchi method was microwave power of 800 W, irradiation time of 17 min, impregnation ratio of 2, and acid concentration of 85%. The noise factor (particle size of raw material) was considered in a separate outer array, which had no effect on the quality of the activated carbon as confirmed by t-test. Activated carbon prepared at optimum combination of control factors had high BET surface area of 1,473.55 m² g-1 and high porosity. The adsorption equilibrium and kinetic data can satisfactorily be described by the Langmuir isotherm and a pseudo-second-order kinetic model, respectively. The maximum adsorbing capacity suggested by the Langmuir model was 1000 mg g-1.

Legalizing physician-assisted suicide and/or euthanasia: Pragmatic implications

Objective: Despite the availability of palliative care in many countries, legalization of euthanasia and physician-assisted suicide (EAS) continues to be debated-particularly around ethical and legal issues-and the surrounding controversy shows no signs of abating. Responding to EAS requests is considered one of the most difficult healthcare responsibilities. In the present paper, we highlight some of the less frequently discussed practical implications for palliative care provision if EAS were to be legalized. Our aim was not to take an explicit anti-EAS stance or expand on findings from systematic reviews or philosophical and ethico-legal treatises, but rather to offer clinical perspectives and the potential pragmatic implications of legalized EAS for palliative care provision, patients and families, healthcare professionals, and the broader community.

Method: We provide insights from our multidisciplinary clinical experience, coupled with those from various jurisdictions where EAS is, or has been, legalized.

Results: We believe that these issues, many of which are encountered at the bedside, must be considered in detail so that the pragmatic implications of EAS can be comprehensively considered.

Significance of Results: Increased resources and effort must be directed toward training, research, community engagement, and ensuring adequate resourcing for palliative care before further consideration is given to allocating resources for legalizing euthanasia and physician-assisted suicide.

Method for separating emulsions.

A method for breaking an emulsion of an ionic liq. which is a salt that is in the liq. state at a temp. below 1500°, and an oil, comprising the steps of (a) irradiating the emulsion with microwave radiation; (b) sepg. the emulsion into an ionic liq. phase and an oil phase; and (c) recovering at least one of the phases. The microwave radiation may occur in the presence of an addnl. heating source, an electrostatic field, an acoustic field, or a combination thereof. [on SciFinder(R)]