Synthesis of interdigital capacitors based on particle swarm optimization and artificial neural networks

This article reports on the use of the particle swarm optimization (PSO) algorithm in the synthesis of the planar interdigital capacitor (IDC). The PSO algorithm is used to optimize the geometry parameters of the IDC in order to obtain a certain capacitance value. The capacitance value of the IDC is evaluated using an artificial neural network (ANN) model with the geometry parameters of the IDC as its inputs. Several design examples are presented that illustrate the use of the PSO algorithm, and the design goal in each example is easily achieved. Full‐wave electromagnetic simulations are also performed for some of the studied IDC structures implemented using coplanar waveguide (CPW) technology. The simulation results are in good agreement with those obtained using the ANN/PSO algorithm. © 2006 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2006.     

Prediction of the backwater level due to bridge constriction in waterways

This article proposes a mathematical method to calculate the backwater level at bridge constrictions for compound channels. Such a model is necessary, as many of the previously developed simple formulas yield inaccurate results. Parametric studies on a single‐opening semicircular arch, single‐opening semielliptical arch and single‐opening straight deck bridge were also conducted using the commercial software HEC‐RAS to investigate the influences of different factors on backwater level. The results indicated that the Froude number, opening ratio, discharge and roughness coefficient impact the backwater level considerably. Hence, a simple mathematical method was developed based on these parameters and validated using experimental data in a symmetrical two‐stage channel with different roughness coefficients for different types of bridge models. The results obtained using the proposed formula corresponded well with the experimental data and the results obtained using the energy method, which is accurate and the most commonly used method to calculate backwater level.     

Organokines in Rheumatoid Arthritis: A Critical Review

Rheumatoid arthritis (RA) is a systemic autoimmune disease that primarily affects the joints. Organokines can produce beneficial or harmful effects in this condition. Among RA patients, organokines have been associated with increased inflammation and cartilage degradation due to augmented cytokines and metalloproteinases production, respectively. This study aimed to perform a review to investigate the role of adipokines, osteokines, myokines, and hepatokines on RA progression. PubMed, Embase, Google Scholar, and Cochrane were searched, and 18 studies were selected, comprising more than 17,000 RA patients. Changes in the pattern of organokines secretion were identified, and these could directly or indirectly contribute to aggravating RA, promoting articular alterations, and predicting the disease activity. In addition, organokines have been implicated in higher radiographic damage, immune dysregulation, and angiogenesis. These can also act as RA potent regulators of cells proliferation, differentiation, and apoptosis, controlling osteoclasts, chondrocytes, and fibroblasts as well as immune cells chemotaxis to RA sites. Although much is already known, much more is still unknown, principally about the roles of organokines in the occurrence of RA extra-articular manifestations.     

Coplanar waveguide-fed slot antennas on cylindrical substrates

This paper describes cylindrical coplanar waveguide (CCPW)-fed slot and folded slot antennas encompassing cylindrical substrates. Using a 1.27 cm diameter Teflon substrate, antennas that operate around 7 GHz have been realized with gains of 1.5 dB (slot) and 2.8 dB (folded slot). The antennas have a well-defined pattern null of 8 dB along the side of the CCPW feedline. A 1.6 GHz slot antenna on a 1.27 cm diameter alumina substrate was also fabricated using a novel direct-write technique, and shown to have comparable performance characteristics.The results include measured data and simulated data using a 3D cylindrical finite difference time domain (FDTD) code.     

A reinvestigation of a colorimetric method aimed at quantifying minute amounts of carboxylic acids present in polystyrene and poly(n‐alkyl methacrylate)s

A reinvestigation of a method (Christoff, M.; Yamaki, S. B.; de Oliveira, M. G.; Atvars, T. D. Z. J. Appl. Polym. Sci. 2004 , 92, 830–838) aimed at quantitatively determining trace amounts of residual carboxylic acid functional groups in polymethacrylates and polystyrene has been carried out. The original technique was based on the monitoring of an absorption band in the UV–visible region (610 nm) that appears after known amounts of polymer are added to a benzene solution containing the basic form of the Nile Blue A dye. It is shown here that the assumption upon which the methodology is based, that is, the occurrence of a 1:1 stoichiometric and complete proton transfer of the carboxylic acid to the dye, is invalid and yields greatly underestimated values for the COOH contents, possibly by 2–3 orders of magnitude. In addition, temperature strongly influences the equilibrium constant for the acid‐base reaction. Lastly, preparation and storage of the analytical solution was found to be problematic, supporting earlier claims that hydrolysis of Nile Blue A base does occur when preparing the benzene solution and/or over storage, yielding Nile Red dye whose absorption in the visible part of the spectrum significantly overlaps. Based on the above results, further use of this technique, at least in its quantitative version, should be discouraged. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44931.     

Quasi-static analysis of asymmetric cylindrical coplanar waveguides with finite-extent ground

Quasi-static characteristics of asymmetric cylindrical coplanar waveguides (CCPWs) with finite-extent ground are analysed using the conformal mapping technique. Closed-form expressions for the effective permittivity and characteristic impedance of inside and outside asymmetric CCPWs with finite ground are derived. Using these expressions, the effect of various parameters on the characteristics of CCPWs is studied.     

Analysis of slot-coupled transitions from microstrip-to-microstripand microstrip-to-waveguides

This paper provides an accurate, versatile, and computationally efficient method for the analysis of slot-coupled transitions from microstrip-to-microstrip, and microstrip-to-rectangular and parallel-plate waveguides. The accuracy of this method is ensured by satisfying all the boundary conditions through a mixed electric-magnetic current integral equation formulation, combined with the moment method. Computational efficiency is achieved by limiting the discretization to only the strips and apertures and by using the accurate and rapidly convergent complex images. To verify the accuracy of this method, the transitions are analyzed using the finite-difference time-domain (FDTD) method. Experimental results are also obtained for some structures. Close agreement is found between the complex image results, the FDTD results, and experiment over a wide frequency range     

Sodium saccharin inhibits adenylyl cyclase activity in non-taste cells

We have studied the in vitro effect of sodium saccharin (NaSacch) on the rat adipocyte adenylyl cyclase complex. NaSacch (2.5-50 mM) inhibited significantly in a dose-dependent manner basal and isoproterenol-stimulated cAMP accumulation on isolated rat adipocytes. Similarly, NaSacch (2.5-50 mM) inhibited forskolin-stimulated adenylyl cyclase activity measured in the presence of Mg(2+)-ATP on adipocyte, astrocyte and thyrocyte membrane fractions. In contrast, NaSacch did not inhibit but slightly increased the forskolin-stimulated adenylyl cyclase activity measured in the presence of Mn(2+)-ATP and GDP beta S, a stable GDP analogue. The effect of NaSacch was not mediated through either the A1-adenosine receptor (A1R) or the alpha 2-adrenergic receptor (alpha 2AR). The inhibitory effect of NaSacch was additive to that of A1R agonist and was not blocked by the addition of the alpha 2AR antagonist RX 821002. Pretreatment of adipocytes with pertussis toxin slightly attenuated but did not abolish the inhibitory effect of NaSacch on forskolin-stimulated adenylyl cyclase activity on membrane fractions. These data suggest that the inhibitory effect of NaSacch on forskolin stimulated-adenylyl cyclase in adipocytes does not imply only Gi protein but also other direct or indirect inhibitory pathway(s) which remain to be determined.     

Junction parameters for silicon devices characterization

An innovative method for device characterization is developed to qualify microelectronic devices. The method is based on parameter extraction from the junction I–V characteristics. Their evolution during electrical aging and ionizing radiation experiments allows an evaluation of the magnitude of the degradation. Results obtained with commercial samples show a signature of both manufacturer and technological processes. This method is easy to implement in a control process for device characterization.