Effect of Hibiscus sabdariffa and its anthocyanins on some reproductive aspects in rats

An aqueous extract of Hibiscus sabdariffa L. is a common beverage in many parts of the world. Reports on its effect on reproduction are conflicting, with anecdotal evidence that the plant is an aphrodisiac, while others report that it is estrogenic, and adversely affects spermatogenesis in rats. We have studied the effect of different concentrations of aqueous extracts of H. sabdariffa calyces (10%, 15% and 20%) used as drinking water for 10 consecutive weeks, and its anthocyanins (50, 100, 200 mg/kg for 5 days, orally) on the weight and histology of the testis, and on some biochemical constituents in testicular homogenates, in addition to the plasma concentrations of testosterone, luteinizing hormone and estradiol. The possible presence of an estrogenic effect of the extract and anthocyanins on the uteri of immature female rats was also tested. Neither the H. sabdariffa extract nor the anthocyanins significantly altered either testicular weight and histology, or uterus weight. Plasma concentrations of the three hormones studied, the testicular concentrations of protein, reduced glutathione and total cholesterol, and superoxide dismutase activity were all insignificantly affected by either the extract or the anthocyanins, except for a slight, but statistically significant, decrease in testicular protein concentration caused by the 15% aqueous extract when compared with controls. These results suggest that H. sabdariffa exerts no adverse effect on the male reproductive system. Consumption of H. sabdariffa aqueous extract inhibited the growth of the rats compared with the controls.     

Probing new physics through B→Kl + l − decays in R-parity violating minimal supersymmetric standard model

We study the decay rate of the process B→Kl ⁺ l ^? (l=e,μ) and some of its other related observables, like the forward–backward asymmetry (A _FB), polarization asymmetry (PA), double branching ratio and CP asymmetry (A _CP) in the R-parity violating Minimal Supersymmetric Standard Model ( $\not \!{R}_{p}$ MSSM). We have performed an error analysis of the differential branching fraction, A _FB and CP asymmetry. The analysis shows that theoretical results based on $\not \!{R}_{p}$ MSSM as an additional effect are compatible with the standard model. A _FB is found to be zero, in agreement with SM. The average A _CP is not only found to be significant in comparison with SM, but it is also compatible with the measured value within errors.     

Sorption characteristics of caffeine onto untreated polyurethane foam: application to its determination in human plasma

In the present paper, the sorption properties of caffeine (CAF) onto polyether type polyurethane foam (PUF) as solid phase sorbent were investigated with UV determination at 274.3 nm. Batch and column methods were used to optimize chemical, flow, kinetic and isothermal conditions for preconcentration of CAF. Results indicated quantitative sorption of CAF at pH 8 and 30 min shaking time. The maximum sorption capacity was found to be 4.1 mg g(-1). Column preconcentration was recommended at a flow rate of 1.5 mL min(-1) and desorption with 4 mL from 0.15 mol L(-1) hydrochloric acid. The procedure provided a linear analytical range of 0.05-30 mg L(-1). The detection and quantification limits are 0.016 and 0.047 mg L(-1), respectively. The procedure was applied to determination of CAF in spiked human plasma. The obtained recoveries were 98-101% and RSD values were from 0.05 to 9.5%.     

Spectroscopic investigations on Tb3+ doped lead fluoroborate glasses

This article presents the optical properties of Tb³⁺ in lead fluoroborate glasses of the type X PbF₂·(89–X)B₂O₃·10 Al₂O₃·1Tb₂O₃ (where X=8, 12, 16, 20, 24, 28, 34 and 36). The standard Judd–Ofelt model was applied to the room temperature absorption intensities of Tb³⁺ (4 f⁸) to determine the phenomenological intensity parameters Ω₂, Ω₄ and Ω₆. These parameters have been used to calculate radiative transition probabilities (A_rad), lifetimes (τ_R) and branching ratios (β_R) for the excited level ⁵D₄. The predicted values of τ_R are compared with the measured values for ⁵D₄ level for eight glass compositions (Glass (A–H)). Among the eight-terbium glasses Glass A with 8 mol% of PbF₂ (as the optimum content) has revealed an intense green emission with maximum life time and higher quantum efficiency. The stimulated emission cross section σ(λ_P) is also evaluated for the ⁵D₄→⁷F_J (J=6, 5, 4 and 3) transitions.     

Parameter identification of TSK neuro-fuzzy models

In the framework of the TSK neuro-fuzzy model a combination of the two well-known identification methods are employed for parameter estimation of the neuro-fuzzy inference system, namely the series–parallel and the parallel configurations. The presented paper proposes two new possible configurations for identifying the parameters of the TSK neuro-fuzzy model using the combinations of these two existing configurations. One of the proposed configurations constitutes the series–parallel configuration to the premise part and the parallel configuration to the consequent part of the neuro-fuzzy model, termed as PS-P configuration. The second one is composed of the series–parallel configuration to the consequent part and the parallel configuration to the premise part of the neuro-fuzzy model, termed as CS-P configuration. The presented work mainly deals with a comparative study of the proposed configurations and the existing configurations in the context of parameter identification of the TSK neuro-fuzzy model on three different benchmark examples. Moreover, it investigates upper bound of the learning rates, using the Lyapunov stability theorem, to assure the stability and the convergence of the model learning process. Implementation of the modified mountain clustering (MMC) and the cluster validity function yields initial models. To restrict the upper bound during the learning process it also presents a two-phase adaptive learning rate.     

Ion chromatography coupled with fluorescence/UV detector: A comprehensive review of its applications in pesticides and pharmaceutical drug analysis

Ion chromatography (IC) is a well-known technique for trace determination of inorganic ions and small organic acids. Recently, it has also appeared as a promising alternative to reverse phase chromatography for the determination of polar pesticides and pharmaceutical drugs in various sample matrices. Therefore, this study aims to provide a comprehensive overview of the application of IC coupled to fluorescence (FLD) or UV detector for the determination of pesticides and pharmaceutical drugs in samples from all walks of life. Apart from advantages and limitations, a short comparison of IC-FLD/UV with other techniques especially reverse-phase chromatography was drawn to envision future research efforts in this direction. Finally, several related areas such as IC hyphenation with different detectors (spectroscopic and spectrometer), miniaturization, automation, green chemistry, mobile phase, column, sample preparation, etc., were discussed to highlight its application for the determination of a wide range of analytes in the complex sample matrix.     

Inhibition of Silver Corrosion in Nitric Acid by Some Aliphatic Amines

The inhibition of silver corrosion in dilute nitric acid (0.01 M) was studied using electrochemical polarization technique in the presence of different concentrations of methylamine, ethylamine, n-propylamine, and n-butylamine. It was found that the inhibition efficiency obtained from Tafel plots improved when the inhibitor concentration and the length of the alkyl chain were increased. The inhibition efficiency increased markedly with increase the additive concentrations according to the following order: methylamine < ethylamine < n-propylamine < n-butylamine. The inhibition action of such compounds occurred by simple blocking of amines on the electrode surface through adsorption process according to Temkin adsorption isotherm. The nearly constant values of the anodic Tafel slopes indicated that the presence of such amines do not affect the mechanism of metal dissolution.     

Nonionic Surfactant Vesicles as a Carrier for Transdermal Delivery of Frusemide

The aim of the present study was to formulate and evaluate the nonionic surfactant vesicles of frusemide in order to enhance its skin permeation. The process variables which could affect the preparation and properties of the niosome formulation studied included type of spans, ratio of span and cholesterol, ratio of cholesterol and dicetylphosphate (DCP), concentration of drug, type of solvent, hydration media and time of hydration. The formulated niosomes thus were characterized for various parameters such as surface morphology, size, entrapment efficiency, skin permeation, etc. Stability of the niosomes in terms of drug holding capacity was assessed for a period of 30 days on storage under defined conditions. The maximum entrapment efficiency of 77.73±2.36% was obtained with niosomes formulated from Span 60∶Cholesterol∶DCP (47.5∶47.5∶5) using chloroform:methanol (4∶1) as the solvent system at the hydration time of 1 hr. A direct relationship was observed between the percentage leaching of the drug out of the vesicles and temperature. Higher transdermal flux was obtained with niosomal gel (9.2±0.5 μg/cm²/hour) in comparison to conventional gel (6.4±0.3 μg/cm²/hour).     

Development of a Parallel-Tandem Column Interface in a Two-Dimensional Liquid Chromatography System

An ion exchange-reversed-phase two-dimensional liquid chromatography (2D-LC) system was developed based on a newly designed interface. The interface was constructed by alternately connecting tandem columns to one of the parallel separation columns to increase the separation efficiency. Separation on the tandem column does not affect the switching frequency; the valve switching could be maintained at high frequency. The constructed interface could be used in both ambient and elevated temperature modes. Under high-temperature mode, only the tandem column was heated, which simplified the operation, decreased the backpressure, improved the solvent compatibility, and speeded up the separation. Tryptic digestion of four proteins was used to evaluate the performance of the developed system. The peak capacity of the 2D-LC system reached 650 under ambient conditions and 890 under high temperature conditions. When compared with the traditional parallel column interface constructed in this paper, the new interface produced a 60% higher peak capacity.     

Exploring the potential role of visual reasoning tasks among inexperienced solvers

The collective case study described herein explores solution approaches to a task requiring visual reasoning by students and teachers unfamiliar with such tasks. The context of this study is the teaching and learning of calculus in the Palestinian educational system. In the Palestinian mathematics curriculum the roles of visual displays rarely go beyond the illustrative and supplementary, while tasks which demand visual reasoning are absent. In the study, ten teachers and twelve secondary and first year university students were presented with a calculus problem, selected in an attempt to explore visual reasoning on the notions of function and its derivative and how it interrelates with conceptual reasoning. A construct named “visual inferential conceptual reasoning” was developed and implemented in order to analyze the responses. In addition, subjects’ reflections on the task, as well as their attitudes about possible uses of visual reasoning tasks in general, were collected and analyzed. Most participants faced initial difficulties of different kinds while solving the problem; however, in their solution processes various approaches were developed. Reflecting on these processes, subjects tended to agree that such tasks can promote and enhance conceptual understanding, and thus their incorporation in the curriculum would be beneficial.