Stochastic load modelling for electric energy distribution applications

Summary The problem of electric load modelling for low aggregation levels is addressed in this paper. The objective is to obtain good “demand” and “response” behaviour models of any group of loads in an electric energy distribution system for any of the functional applications that are beeing considered in the framework of the Distribution Management Systems, aimed to improve the energy efficiency, reliability and quality of the system. A brief critical revision of the methodologies used for that purpose is in the paper, and the advantages of using approaches where physical knowledge about the load characteristics is used, are stated and demonstrated.     

Synchronous-derivative phosphorimetric determination of 1- and 2-naphthol in irrigation water by employing beta-cyclodextrin

A room-temperature phosphorimetric (RTP) study of the inclusion process between 1- and 2-naphthol, beta-cyclodextrin (beta-CD) and 3-bromo-1-propanol as heavy atom pertuber has been performed. Experimental conditions were optimized for the formation of trimolecular complexes with lifetimes of 10.82 and 9.41 ms for 1- and 2-naphthol, respectively. A synchronous-derivative room-temperature phosphorimetric method has been proposed to the analysis of both naphthols in synthetic mixtures and irrigation water in the ratio 1:10 to 10:1; the limit of detection is 0.02 mug ml(-1) and the relative standard deviation (RSD) is about 6%.     

Intercalation of Toluidines into α-Zirconium Hydrogenphosphate

Intercalates of o-, m-, and p-toluidine into α-Zr(HPO₄)₂ · H₂O were prepared and characterized by powder X-ray diffraction, thermogravimetric analysis and infrared spectroscopy. As follows from IR, toludine molecules are protonated in the interlayer space. Toluidine molecules are arranged in a bimolecular way in the intercalates containing more than 1.5 toluidine molecules per Zr atom. On the other hand, a monolayer of the toluidine molecules is supposed in the intercalates with less than one toluidine molecule per Zr atom.     

Short-Chain Di-Ureasil Ormolytes Doped with Potassium Triflate: Phase Diagram and Conductivity Behavior

Di-urea cross-linked poly(oxyethylene)/siloxane hybrids, synthesized by the sol-gel process and containing a wide concentration range of potassium triflate, KCF₃SO₃, have been analyzed by x-ray diffraction and differential scanning calorimetry. The pseudo-phase diagram proposed has been taken into account in the interpretation of the complex impedance measurements. The xerogels prepared are obtained as transparent, thin monoliths. At room temperature the highest conductivity found was 2 × 10^{–6 –1} cm^–1.     

Characterization and X-ray crystal structure of butanoylsalophencobalt(III)

The synthesis and characterization of the pentacoordinated butanoylsalophencobalt(III) compound, including X-ray analysis, are described. The chemical shift in the ¹³C-n.m.r. of the carbonyl carbon was determined by means of an HMBC experiment. Collision induced dissociation (CID) and high resolution mass spectrometry were used to establish the fragmentation pattern of the CoC₂₄H₂₁N₂O₃ compound. X-ray diffraction analysis shows the presence of two conformations for the acylsalophen ligand system in the same monocrystal, as well as two different OH–C hydrogen bonds with unusual interactions.     

Novel bis (crown ether)-based potassium sensor for biological applications

Based on structure-selectivity studies on bis-benzo-crown ether derivatives, 2,2-bis[3,4-(15-crown-5)-2-nitrophenylcarbamoxymethyl]tetradecane (BME-44) was designed and synthesized. The performance characteristics of this new, highly lipophilic ionophore of the group of bis-nitrobenzo-15-crown-5 derivatives with urethane linkage when used in liquid membrane electrodes are evaluated with special regard to the requirements of biological and clinical applications. Potentiometric steady-state and flow-through dynamic data are presented to prove the sensor capabilities for clinical and physiological potassium determinations.Dedicated to Professor W. Simon on the occasion of his 60th birthday     

Colour change and tautomerism of some azo-indicators on complex formation with cyclodextrins

Complex formation of methyl orange and some other azobenzene derivatives with cyclodextrins has been studied in acidic and alkaline solutions by a spectrophotometric method. A correlation has been established between the stability constants of the complexes, the spectral changes accompanying complex formation and a tautomeric equilibrium between protonation on the azo and dimethylamino group. Our own results have been compared with some literature data, and equilibrium constants for the tautomeric rearrangement have been calculated. It has been demonstrated that the significant colour changes observed with the protonated forms only (and not with the corresponding bases) is really caused by a shift of the tautomeric equilibrium.     

A Simple and Straightforward Procedure for Monitoring Phenol Compounds in Waters by Using UV Solid Phase Transduction Integrated in a Continuous Flow System

 A novel and sensitive flow-through method with solid phase UV spectrophotometric transduction is proposed for the direct determination of phenols: phenol, 1-naphthol, 2-naphthol, 3,4-dimethylphenol and 2,4-dichlorophenol were used as test phenol compounds. The device consists of a monochannel system using Sephadex QAE A-25 resin as packing material of the detection microzone placed inside a flow-through cell on which phenols are temporarily retained. Intrinsic absorbances are monitored at 237 nm for phenol, 242 nm for 2-naphthol and 3,4-dimethylphenol, and 247 nm for 1-naphthol and 2,4-dichlorophenol. The sample is transported by a alkaline carrier solution which acts as desorbing the solution itself. The determination of phenols was carried out for 40 and 600 μL of sample volume. The sensitivity is higher by a factor of 10 than that provided by a conventional flow injection analysis method. The detection limits were found to be close to 1 ng mL⁻¹ in some cases (using 600 μL of sample volume). The relative standard deviations (n=10) ranged between 1.5 and 3.2% (40 μL) and 1.1 and 2.2% (600 μL). The proposed method has shown good results in its application to waters, making this method suitable for phenol monitoring. Correspondence: Department of Physical and Analytical Chemistry, Faculty of Experimental Sciences, University of Jaén, 23071 Jaén, Spain. e-mail: amolina@ujaen.es Received February 27, 2002; accepted October 11, 2002     

Direct determination of 1-naphthoxylactic acid in biological fluids by non-protected fluid room temperature phosphorimetry

A selective and sensitive room-temperature phosphorimetric method for the direct determination of 1-naphthoxylactic acid (NA) in biological fluids is described. It is based on obtaining a phosphorescence signal from NA using TlNO3 as a heavy atom perturber and Na2SO3 as a deoxygenator without a protective medium. This technique is named non-protected room-temperature phosphorescence (NP-RTP), which allows to determine analytes in complex matrices without the need for tedious prior separation. Optimization of the operational conditions resulted in a detection limit for NA of 9.6 ng/mL according to the error propagation theory. The repeatability and standard deviation were also determined. This method was successfully applied to the determination of NA in urine and human serum.