Scattering of an arbitrarily oriented dipole field by an infinite and a finite length PEMC circular cylinder

Electromagnetic scattering from an infinite and a finite length PEMC circular cylinder, illuminated by an arbitrarily oriented dipole, is investigated theoretically. An electric dipole as a source of excitation is considered first, and then a magnetic dipole as a source of excitation is treated. In contrast to the case of an axially directed dipole, it is shown that no additional terms are needed to incorporate the cross-polarized component of the field for the case of radial and circumferential dipoles. Numerical verifications are presented to verify the validity of derived results and numerical code by comparing results with the published literature.      

Effect of electrolytes on the cloud point of chlorpromazine hydrochloride solutions

Cloud point (CP) phenomenon occurring in amphiphilic drug chlorpromazine hydrochloride (CPZ) solutions with and without salts is reported herein. The CP of a 50mM CPZ solution (prepared in 10mM sodium phosphate, SP, buffer) was found to decrease with increasing pH, both in the absence as well as presence (50mM) of added salts (NaCl, NaBr, LiBr, KBr, tetra-n-butylammonium bromide). Whereas, at a fixed concentration of NaCl, the CP increased with increasing CPZ concentration, addition of increasing amounts of salts (NaF, NaCl, NaBr, LiCl, KCl) to 50mM CPZ solution (at pH 6.7) caused continuous increase in CP. On the basis of these studies the binding-effect orders of counterions and co-ions have been deduced, respectively, as: Br(-)>Cl(-)>F(-) and Li(+)>Na(+)>K(+). The similar trend of increasing CP with addition of increasing amounts of quaternary bromides (tetramethylammonium bromide, TMeAB; tetraethylammonium bromide, TEtAB; tetra-n-propylammonium bromide, TPrAB; tetra-n-butylammonium bromide, TBuAB; tetra-n-pentylammonium bromide, TPeAB) to 50mM CPZ solutions (at pH 6.7) was found to be dependent upon the alkyl chain length of the particular salt. The overall behaviour has been discussed in terms of electrostatic interactions, micellar growth, and mixed micelle formation.     

Thermal stabilisation of PVC—An alternative approach

Although the Frye and Horst^1–3 theory of PVC stabilisation has been widely accepted, it has also been subject to some criticism. An alternative approach to the stabilisation of PVC, based on polar interactions within the PVC matrix, is postulated. Some of the results of research in this area which may be explained more convincingly on the basis of this approach are discussed in this paper.     

Radiosynthesis and Biodistribution of <Superscript>99m</Superscript>Tc-Metronidazole as an <Emphasis Type="Italic">Escherichia coli</Emphasis> Infection Imaging Radiopharmaceutical

Bacterial infection poses life-threatening challenge to humanity and stimulates to the researchers for developing better diagnostic and therapeutic agents complying with existing theranostic techniques. Nuclear medicine technique helps to visualize hard-to-diagnose deep-seated bacterial infections using radionuclide-labeled tracer agents. Metronidazole is an antiprotozoal antibiotic that serves as a preeminent anaerobic chemotherapeutic agent. The aim of this study was to develop technetium-99m-labeled metronidazole radiotracer for the detection of deep-seated bacterial infections. Radiosynthesis of ^99mTc-metronidazole was carried by reacting reduced technetium-99m and metronidazole at neutral pH for 30 min. The stannous chloride dihydrate was used as the reducing agent. At optimum radiolabeling conditions, ~ 94% radiochemical was obtained. Quality control analysis was carried out with a chromatographic paper and instant thin-layer chromatographic analysis. The biodistribution study of radiochemical was performed using Escherichia coli bacterial infection-induced rat model. The scintigraphic study was performed using E. coli bacterial infection-induced rabbit model. The results showed promising accumulation at the site of infection and its rapid clearance from the body. The tracer showed target-to-non-target ratio 5.57 ± 0.04 at 1 h post-injection. The results showed that ^99mTc-MNZ has promising potential to accumulate at E. coli bacterial infection that can be used for E. coli infection imaging.     

Non-destructive evaluation of concrete samples using PGNAA technique

Non-destructive evaluation of concrete is an important task of quality control in building construction industry. The quality evaluation of concrete samples was carried out using prompt gamma ray activation analysis (PGNAA) technique. In this study calcium and silicon contents of six concrete samples were determined through yield of 1.94 MeV gamma-rays from calcium and 3.54 MeV gamma-rays from silicon. The concrete samples were prepared by mixing cement, coarse and fine aggregates in different proportions. A linear correlation has been observed between the experimental yield of the prompt gamma rays and the actual calcium and silicon concentration in the concrete samples. Results of this study have demonstrated successful use of an accelerator-based PGNAA setup in non-destructive analysis of the concrete samples.     

Scattering from a PEC strip buried in non-integer dimensional planar grounded dielectric slab by using Kobayashi potential method

Solution for electromagnetic scattering from a perfect electric conducting strip buried in a planar grounded dielectric slab is determined by using the Kobayashi Potential Method. It is assumed that the dimension of mediums, above and within the slab, is non-integer in the direction normal to interface of the slab. The scattering problem is divided into two parts. In the first part, fields in the absence of strip are determined for plane wave excitation. In the second part, presence of the strip is taken into account. It has been assumed that spacings between the strip and interfaces of the slab are comparatively very larger than the wavelength of monochromatic operating frequency. Due to this assumption, scattered field after reflection from the interfaces has no interaction with the strip. In order to gains more insight, several special cases of the geometry are treated. Using saddle point method, far-zone scattered field for region above the grounded slab is also determined.     

ThioCORMates: Tunable and Cost-Effective Carbon Monoxide-Releasing Molecules

Carbon monoxide-releasing molecules (CORMs) can offer a safer alternative to CO delivery than the use of CO gas cylinders. Upon treatment with an amine base, S-aryl thioformates (“thioCORMates”) release CO nearly quantitatively at room temperature, a gas which can then be harnessed for carbonylative cross-coupling, biological study, or inorganic synthesis. These bench-stable molecules are easily synthesized from the corresponding thiophenol and can be electronically tuned to release CO at different rates-from less than 1 min to greater than 1 h-offering a practical alternative to existing CORM technology. Finally, isotopically labeled ¹³CO can be conveniently generated and used, with the thioCORMate synthesized from ¹³C-formic acid.     

Inverted Region in Intermolecular Electronic Energy Transfer

A critique of some recent publications (concerning the so-called inverted region in exchange-induced electronic energy transfer) is presented. It is first pointed out that the phenomena reported therein have in fact been known for nearly two decades; next, a derivation of the expression (used in the aforementioned communications) for k _EnT, the transfer rate constant, is presented; finally, it is stressed that this formula cannot provide reliable quantitative predictions.     

A Comparison of the Singlet-Singlet and Triplet-Triplet Spectra of Some Typical Symmetrical Cyanine Dyes

The triplet-triplet (T-T) spectra of twelve symmetrical cyanine dyes have been recorded, using flash photolysis in the presence of triplet state sensitizers. Three sets of dyes have been studied, each set comprising four members which differ from one another by the length of the bridge joining two identical nuclei (quinoline or benzthiazole); the internuclear linking is made by one =CH-, or by a chain composed of three, five, or seven such groups. Excluding the shortest member of each set, the remaining nine dyes are found to follow a common trend: the wavenumber of the 0-0 vibrational peak of the most intense T-T absorption band is linearly related to that of the 0-0 peak of the first singlet-singlet absorption band.     

Singlet oxygen quenching by thione analogues of canthaxanthin, echinenone and rhodoxanthin

Thione analogues of three naturally occurring carotenones (canthaxanthin, echinenone, and rhodoxanthin) were synthesized just over ten years ago, and it was reported that substitution of the oxygen atom by sulphur brings about a large red shift and some broadening in the optical absorption spectrum of the compound. Since the three carotenothiones are scarce, determination of their molar absorption coefficients presents a challenge. A method for relating the molar absorption coefficient of a carotenothione (Car-S) to that of its ketone analogue (Car-O) has been developed, which has revealed that the peak molar absorption coefficient of a Car-S is only about 60% of the corresponding value for Car-O. Using methylene blue as the sensitizer and acetonitrile as the solvent, we have also investigated the quenching (under photostationary conditions) of the 1270nm phosphorescence emission of singlet oxygen by each of the six carotenoids. The data conform to the Stern-Volmer relation, and show that substitution of a carbonyl oxygen atom by sulphur does not lead to an appreciable change in the value of the quenching constant, which is close to 1.5 x 10(10)M(-1)s(-1) for all six quenchers.