Spectrophotometric Determination of Piroxicam via Chelation with Fe(III) in Commercial Dosage Forms

The objective of this work is to develop and validate spectrophotometric method for the determination of piroxicam in commercial dosage forms. The method is based on the chelation of the drug with Fe(III) to form pink coloured metal chelate at room temperature which absorbs maximally at 504 nm. Beer's law is obeyed over the concentration range of 8–160 μg mL^?1 (A = 1.07 × 10^?3 + 7.75 × 10^?3 C). Under the optimized experimental conditions, proposed method is validated as per the International Conference on Harmonisation guidelines. The limits of detection and quantitation for the proposed method are 0.775 and 2.348 μg mL^?1, respectively. The proposed method has been successfully applied to the determination of piroxicam in commercial dosage forms. The results are compared with the reference El‐Ries et al. spectrophotometric method.     

A twice liquid arc discharge approach for synthesis of visible-light-active nanocrystalline Ag:ZnO photocatalyst

Ag:ZnO hybrid nanostructures were successfully prepared by a twice arc discharge method in liquid. The visible light photocatalytic activities were successfully demonstrated for the degradation of Rhodamine B (Rh. B), Methyl orange (MO), and Methylene blue (MB) as standard organic compounds under the irradiation of 90 W halogen light for 2 h. The Ag:ZnO nanostructures were characterized by X-Ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and ultraviolet-visible absorption spectroscopy (UV-Vis). The results revealed that the Ag:ZnO nanostructures extended the light absorption spectrum toward the visible region and significantly enhanced the Rh. B photodegradation under visible light irradiation. 3 mM Ag:ZnO nanostructures exhibited highest photocatalytic efficiency. It has been confirmed that the Ag:ZnO nanostructures could be excited by visible light (E<3.3 eV). The significant enhancement in the Ag:ZnO nanostructures photocatalytic activity under visible light irradiation can be ascribed to the effect of physisorbed noble metal Ag by acting as electron traps in ZnO band gap. A mechanism for photocatalytic degradation of organic pollutant over Ag:ZnO photocatalyst was proposed based on our observations.     

Determination of Chlorophenoxy Acid Herbicides in Water Samples by Suspended Liquid-Phase Microextraction�CLiquid Chromatography

In this study, directly suspended liquid-phase microextraction was investigated for the extraction and determination of five chlorophenoxy acid herbicides in water samples. The optimized parameters for extraction of chlorophenoxy acid herbicides were 1 M HCl concentration in sample solution, solution temperature 20 °C, 45-min extraction time, 1,000 rpm stirring rate, 25 ??L extracting solvent volume and without NaCl addition. Under the optimum conditions, the enrichment factor ranged from 192 to 390. Calibration curves yielded good linearity (R ² > 0.999) and the linear range was 5.0?C500.0 ??g L^?1, limit of detection was 0.3?C0.4 ??g L^?1 and limit of quantification was 1?C2 ??g L^?1 for analytes and the relative standard deviations were in the range of 3?C10% (n = 3). Finally, the proposed method was successfully applied to the quantification of five chlorophenoxy acid herbicides in water samples and recovery was in the range of 74?C110%.     

Poly(N‐Bromobenzene‐1,3‐Disulfonylamide), N,N,N′,N′‐Tetrabromobenzene‐1,3‐Disulfonylamide and DABCO‐Bromine Complex: As Novel Reagents for the Oxidative Coupling of Thiols to Disulfides

An efficient method for the oxidative coupling of thiols to their corresponding disulfides by new reagents poly(N‐bromobenzene‐1,3‐disulfonylamide) PBBS , N,N,N′,N′‐tetrabromobenzene‐1,3‐disulfonylamide TBBDA and DABCO‐bromine complex is described. The reaction was applicable to a variety of thiols with high chemoselectivity.     

Eugenol: a natural compound with versatile pharmacological actions

Eugenol, the major constituent of clove oil, has been widely used for its anesthetic and analgesic action in dentistry. Eugenol exhibits pharmacological effects on almost all systems and our aim is to review the research work that has identified these pharmacological actions. Eugenol possesses significant antioxidant, anti-inflammatory and cardiovascular properties, in addition to analgesic and local anesthetic activity. The metabolism and pharmacokinetics of the compound in humans have been studied. Eugenol has also been used as a penetration enhancer. The compound is a very promising candidate for versatile applications, and the design of new drugs based on the pharmacological effects of eugenol could be beneficial.     

Adsorption Behaviour of 134Cs and 22Na Ions on Tin and Titanium Ferrocyanides

Tin and titanium ferrocyanides were studied as adsorbents for alkali metal ions, viz., ¹³⁴Cs and ²²Na, which represent radioactive wastes. The ferrocyanides were prepared in granular form. The tin version contained 11.2% water, while the titanium version contained 17.7% water. The exchange capacities for Cs⁺ and Na⁺ in the hydrated tin version were about 1.5 and 0.7 meq/g, respectively, while those in the titanium version were 2.2 and 1.2 meq/g, respectively. Drying at 250°C decimated those capacities. The diffusional time constant of Cs⁺ at 25°C, determined via Fick's second law, was of order of magnitude 1 × 10^–3 s^–1, though there were minor differences due to particle size and the form of ferrocyanide. Similarly, the effective diffusivity was of order of magnitude 1 × 10^–8 cm²/s. The titanium version responded slightly faster than the tin version. Likewise, equilibrium measurements in mixtures with sodium nitrate, potassium nitrate, or uranium oxide, showed that the titanium version exhibited significantly greater selectivity for Cs⁺ than did the tin version. Unfortunately, tests of complete elution of the Cs⁺ from the ferrocyanides were mostly disappointing. Work continues on that subject.     

Iodine‐Catalyzed Friedlander Quinoline Synthesis under Solvent‐Free Conditions

Polyfunctional quinolines were synthesized using Friedlander method catalyzed by molecular iodine in high yields at 60 °C under solvent‐free conditions.     

Methyl orange degradation enhanced by hydrogen spillover onto platinum nanocatalyst surface

Following a thermal reduction method, platinum nanoparticles were synthesized and stabilized by polyvinylpyrrolidone. The colloidal platinum nanoparticles were stable for more than 3 months. The micrograph analysis unveiled that the colloidal platinum nanoparticles were well dispersed with an average size of 2.53 nm. The sol–gel‐based inverse micelle strategy was applied to synthesize mesoporous iron oxide material. The colloidal platinum nanoparticles were deposited on mesoporous iron oxide through the capillary inclusion method. The small‐angle X‐ray scattering analysis indicated that the dimension of platinum nanoparticles deposited on mesoporous iron oxide (Pt‐Fe₂O₃) was 2.64 nm. X‐ray photoelectron spectroscopy (XPS) data showed that the binding energy on Pt‐Fe₂O₃ surface decreased owing to mesoporous support–nanoparticle interaction. Both colloidal and deposited platinum nanocatalysts improved the degradation of methyl orange under reduction conditions. The activation energy on the deposited platinum nanocatalyst interface (2.66 kJ mol^?1) was significantly lowered compared with the one on the colloidal platinum nanocatalyst interface (40.63 ± 0.53 kJ mol^?1).     

In vitro comparative study of vibro-acoustography versus pulse-echo ultrasound in imaging permanent prostate brachytherapy seeds

Background

Permanent prostate brachytherapy (PPB) is a common treatment for early stage prostate cancer. While the modern approach using trans-rectal ultrasound guidance has demonstrated excellent outcome, the efficacy of PPB depends on achieving complete radiation dose coverage of the prostate by obtaining a proper radiation source (seed) distribution. Currently, brachytherapy seed placement is guided by trans-rectal ultrasound imaging and fluoroscopy. A significant percentage of seeds are not detected by trans-rectal ultrasound because certain seed orientations are invisible making accurate intra-operative feedback of radiation dosimetry very difficult, if not impossible. Therefore, intra-operative correction of suboptimal seed distributions cannot easily be done with current methods. Vibro-acoustography (VA) is an imaging modality that is capable of imaging solids at any orientation, and the resulting images are speckle free.

Objective and methods

The purpose of this study is to compare the capabilities of VA and pulse-echo ultrasound in imaging PPB seeds at various angles and show the sensitivity of detection to seed orientation. In the VA experiment, two intersecting ultrasound beams driven at f₁ = 3.00 MHz and f₂ = 3.020 MHz respectively were focused on the seeds attached to a latex membrane while the amplitude of the acoustic emission produced at the difference frequency 20 kHz was detected by a low frequency hydrophone.

Results

Finite element simulations and results of experiments conducted under well-controlled conditions in a water tank on a series of seeds indicate that the seeds can be detected at any orientation with VA, whereas pulse-echo ultrasound is very sensitive to the seed orientation.

Conclusion

It is concluded that vibro-acoustography is superior to pulse-echo ultrasound for detection of PPB seeds.     

SMFs-supported Pd nanocatalysts in selective acetylene hydrogenation: Pore structure-dependent deactivation mechanism

In the present study, CNFs, ZnO and Al₂O₃ were deposited on the SMFs panels to investigate the deactivation mechanism of Pd-based catalysts in selective acetylene hydrogenation reaction. The examined supports were characterized by SEM, NH₃-TPD and N₂ adsorption-desorption isotherms to indicate their intrinsic characteristics. Furthermore, in order to understand the mechanism of deactivation, the resulted green oil was characterized using FTIR and SIM DIS. FTIR results confirmed the presence of more unsaturated constituents and then, more branched hydrocarbons formed upon the reaction over alumina-supported catalyst in comparison with the ones supported on CNFs and ZnO, which in turn, could block the pores mouths. Besides the limited hydrogen transfer, N₂ adsorption-desorption isotherms results supported that the lowest pore diameters of Al₂O₃/SMFs close to the surface led to fast deactivation, compared with the other catalysts, especially at higher temperatures.