Fluoride-selective optical sensor based on aluminum(III)-octaethylporphyrin in thin polymeric film: further characterization and practical application

More detailed analytical studies of a new fluoride-selective optical sensor based on the use of aluminum(III)-octaethylporphyrin and a lipophilic pH indicator (4',5'-dibromofluorescein octadecyl ester; ETH-7075) within a thin plasticized poly(vinyl chloride) film are reported. The sensor exhibits extraordinary optical selectivity for fluoride over a wide range of other anions, including anions with far more positive free energies of hydration (e.g., perchlorate, thiocyanate, nitrate, etc.). UV-visible spectrophotometric studies of the sensing films indicate that fluoride interacts with the Al(III) center of the porphyrin structure, yielding both a change in the Soret band lambda(max) of the porphyrin and a change in the protonation state of the pH indicator within the film. The same change in spectral properties of the metalloporphyrin occurs in the absence of added pH indicator or with added tetraphenylborate derivative anionic sites, but optical responses to fluoride in these cases are shown to be irreversible. The presence of the pH indicator and the simultaneous fluoride/proton coextraction equilibrium chemistry is shown to greatly enhance the reversibility of fluoride binding to the Al(III) porphyrin. Optical response toward fluoride can be observed in the range of 0.1 microM-1.6 mM. Optical selectivity coefficients of <10(-6) for common anions (e.g., sulfate, chloride, nitrate, etc.) and <10(-4) for perchlorate and thiocyanate are obtained. Measurements of fluoride in drinking water via the new optical sensor are shown to correlate well with values obtained for the same samples using a classical LaF3-based fluoride ion-selective electrode method.     

Family planning opinion leadership in Korea, 1971

The characteristics of Korean family planning opinion leaders are assessed through a secondary analysis of the 1971 national survey conducted by the Korean Institute for Research in the Behavioral Sciences. In effect, what characterized Korean family planning opinion leaders was a rather national and democratic model. Those who had tried methods, discussed them, and knew a lot about them assumed leadership roles more than others. Place of residence, education, and other such variables mattered relatively little unless a woman had credibility imparted by actual use and knowledge imparted by use or discussions with family planning professionals.     

Automatic monitoring of deposition conditions during rf sputtering of dielectric materials

Modern optics often require dielectric thin films of precisely controlled optical indices. One method of producing such films is by rf sputtering at extremely low deposition rates (～0·1 μh^?1). Thermal and plasma instabilities occur during the deposition process (often > 10 h duration) and the sputtering system therefore requires continuous monitoring to ensure appropriate corrective action.The objective of this paper is to examine the technology involved in developing supervision circuitry to monitor the parameters of a conventional commercially available rf sputtering system employed in the fabrication of high optical quality dielectric films for integrated-optics applications. The techniques used have overcome the difficulties of operating analogue circuitry in a high rf noise environment.A novel reflection-interferometer, enabling continuous monitoring of sputtered film thickness in a close spaced target-substrate system, was developed. The design has been shown to possess enhanced alignment tolerance, particularly for high refractive index films.     

Hydrogen peroxide induces 21-aminosteroid-inhibitable F2-isoprostane production and cytolysis in renal tubular epithelial cells

F2-isoprostanes are the newly identified reactive oxygen species-catalyzed peroxidation products of arachidonate. The infusion of these prostaglandin F2-like prostanaoids into the rat kidney induces profound parallel reductions in RBF and GFR, suggesting that these metabolites may be partly responsible for the hemodynamic alterations seen in free radical-linked acute renal injury models. The present study examined directly in renal proximal tubular (LLC-PK1) cells whether hydrogen peroxide, a reactive oxygen species implicated in many models of acute renal injury, induces F2-isoprostane production and whether its production can be inhibited by the recently synthesized lipid peroxidation inhibitor 21-aminosteroid (lazaroid U-74389G). The incubation of LLC-PK1 cell layers with hydrogen peroxide for 3 h resulted in a dose-related six-fold increase in F2-isoprostane production, measured by the gas chromatographic-mass spectroscopic method. The preincubation of cells with 21-aminosteroid prevented hydrogen peroxide-induced F2-isoprostane production, a finding also demonstrable with other lipid peroxidation inhibitors, e.g., 2-methyl aminochroman (U-83836E) and diphenyl-p-phenylenediamine. Besides inhibiting isoprostane production, 21-aminosteroid reduced hydrogen peroxide-induced lipid degradation and peroxidation, and protected the cells against hydrogen peroxide-induced cytolysis. The novel finding that hydrogen peroxide induces 21-aminosteroid-inhibitable F2-isoprostane production in renal epithelial cells supports the in vivo report that its levels are elevated in reactive oxygen species-linked renal injury models such as ischemia-reperfusion. Besides direct cell injury, lipid peroxidation by generating F2-isoprostanes may further contribute to renal dysfunction through a vasoconstrictive mechanism. Thus, the inhibition of excess F2-isoprostane production may be one of the additional mechanisms, besides cytoprotection, by which antioxidants ameliorate renal dysfunction in experimental models of acute renal injury.     

Effects of muscarinic agents on cultured human trabecular meshwork cells

Intracellular calcium measurements were performed in cultured human trabecular meshwork cells preloaded with the cell permeant dye fura 2-AM. Fluctuations in calcium levels were then monitored with microscope-based ratio fluorometry. Carbachol increased intracellular calcium in a dose-dependent manner; as did oxotremorine-M, aceclidine, and pilocarpine. Carbachol's effect was blocked by the non-selective muscarinic antagonist atropine, as well as by muscarinic receptor subtype-selective antagonists such as pirenzepine (M1-selective), p-fHHSiD (M3-selective), and 4-DAMP (M1, M3 subtypes). Rank order of potencies for the antagonists' effects was atropine = 4-DAMP > p-fHHSiD > pirenzepine, a profile suggesting that the M3 receptor subtype is essential in the carbachol effect. Phospholipase C activity was estimated via measurement of total production of inositol phosphates in cultured human trabecular meshwork cells pre-exposed to 3H-myoinositol. In these cells, carbachol also stimulated phosphoinositide production in a dose-dependent manner, and an antagonist profile similar to that seen for calcium response was obtained when carbachol was used as the effector. The data indicate that muscarinic effects on cultured human trabecular meshwork calcium mobilization and phospholipase C activity are mediated by an M3-like receptor subtype. Therefore, the muscarinic M3 receptor may play a role in trabecular meshwork cell function(s).     

Handover management based on user’s mobility specification

Considering the highly dynamic nature of wireless networks, the major challenge in this environment is the provision of QoS guarantees that different applications demand. Recent research is interested in advance resource reservation to provide the necessary QoS to the mobile terminals. Another way to obtain a better use of the resources in this environment is to determine the future locations of the mobile terminal. This paper describes a user’s mobility profile management based approach for advance resource reservation in wireless networks; it is based on theNsis signaling. This reservation is based on an objectMspec (Mobility Specification) which determines the future location of the mobile terminal. The mspec object is a part of a user’s mobility profile; this last is determined by the mobile terminal. Another applicability of our user’s mobility profile is in the 4G wireless systems, in this case; the mobile terminal supports various access technologies and the user’s mobility profile is used to adapt the vertical and the diagonal handover to the user’s needs.     

A hybrid HNN-QP approach for dynamic economic dispatch problem

This paper introduces a solution of the dynamic economic dispatch (DED) problem using a hybrid approach of Hopfield neural network (HNN) and quadratic programming (QP). The hybrid algorithm is based on using enhanced HNN; to solve the static part of the problem; the QP algorithm for solving the dynamic part of the DED. This technique guarantees the global optimality of the solution due to its look-ahead capability. The new algorithm is applied and tested to an example from the literature and the solution is then compared with that obtained by some other techniques to prove the superiority and effectiveness of the proposed algorithm.     

Modified Two-Phase Titration Methods to Quantify Surfactant Concentrations in Chemical-Enhanced Oil Recovery Applications

In enhanced oil recovery applications, surfactants are injected into reservoirs along with polymers and salts. The effluents eluted from lab experiments and field tests are analyzed by HPLC methods using an evaporative light scattering detector (ELSD) detector. When the surfactant concentrations are less than 100 ppm, HPLC methods are inaccurate. A novel two-phase titration method is developed where surfactant concentrations can be quantified using a calibration curve constructed with UV/vis absorption. This method can analyze surfactant concentrations 5–80 ppm where dilution eliminates any high-salinity interferences with the absorption measurements. The method is based on formation of a dye-surfactant complex and the light absorption of the complex has a linear correlation with the surfactant concentration. Anionic surfactant concentrations lower than 100 ppm can be accurately quantified using this method with methylene blue. The method was also developed for low concentrations (<50 ppm) of cationic surfactants using methyl orange and indigo carmine. The indigo carmine method can be used without the use of an organic phase. All methods are applicable at salinities up to 3 wt%. Both the methylene blue method and the methyl orange method can be used to detect zwitterionic surfactants. These methods can be used in the presence of polymers without any prior treatments.     

Interference-Aware QoS Guarantees in OFDM-Based Cognitive Radio Networks Based on Branch and Bound

Wireless Personal Communications - In the past decade, the OFDM access method has been widely used in different types of networks. Indeed; OFDM is the technology of choice for all major wireless...     

Diffusing-CRN k-means: an improved k-means clustering algorithm applied in cognitive radio ad hoc networks

With increasing demand of new wireless applications and increasing number of wireless user’s, problem of spectrum scarcity arises. In this context, cognitive radio supports dynamic spectrum access to address spectrum scarcity problem. Cognitive radio defined the cognitive radio nodes by their ability to intelligently adapt the environment to achieve specific objectives through advanced techniques. The variance of channel availability for cognitive radio nodes degrades connectivity and robustness of this type of network; in this case the use of clustering is an effective approach to meet this challenge. Indeed, the geographical areas are homogeneous in terms of type of radio spectrum, radio resources are better allocated by grouping cognitive radio nodes per cluster. Clustering is interesting to effectively manage the spectrum or routing in cognitive radio ad hoc networks. In this paper, we aim to improve connectivity and cooperativeness of cognitive radio nodes based on the improvement of the k-means algorithm. Our proposed algorithm is applied in cognitive radio ad hoc networks. The obtained results in terms of exchange messages and execution time show the feasibility of our algorithm to form clusters in order to improve connectivity and cooperativeness of cognitive radio nodes in the context of cognitive radio ad hoc networks.