Simultaneous Determination of Metronidazole Benzoate Methylparaben, and Propylparaben by High-Performance Liquid Chromatography

The simultaneous determination of metronidazole benzoate (MB), methylparaben (MP), and propylparaben (PP) in an oral suspension formulation was developed using high-performance liquid chromatography (HPLC). The method was developed using a Novapak C₁₈ (3.9 × 150 mm, 4 μm) column, methanol-water (50:50, v/v) as the mobile phase and an ultraviolet (UV) detector at 254 nm. The peak area response versus concentration was linear in a concentration range from 40 to 400 μg/ml of MB, 0.8 to 8.0 μg/ml of MP, and 0.2 to 2.0 μg of PP. The correlation coefficients were 0.9997 for MB, 0.9987 for MP, and 0.9983 for PP, with relative standard errors of 1.12%, 1.28%, and 1.67%, respectively.     

A Formula for the Conversion of 5-Minute Average, 10 Minute Average Rain Rate into 1-Minute Average Rain Rate for Prediction of Rain Induced Attenuation

The attenuation of microwave signal due to rain is a well established fact now. Localized models based on the rain rate and attenuation statistics is the basic necessity for a RF communication system designer. For development of any such model, we need long term statistics. These days most of the metrological data that is available is in the form of either 5-min or 10-min average rain rate and if we want to utilize this data, we need to convert this into 1-min equivalent average rain fall. In this paper, a formula has been purposed for the conversion of 5 min and 10 min average rain rate into 1 min equivalent average rain rate.     

Optical and electrical characterization of conducting polymer-single walled carbon nanotube composite films

The optical and electrical properties of the conducting polymer poly(3-hexylthiophene) and single walled carbon nanotube (SWCNT) composites have been investigated. The composites were prepared by dispersing carbon nanotubes in the polymer matrix already dissolved in 1,2-dichlorobenzene. The optical absorption, photoluminescence (PL) and electrical conductivity of the composite was studied as a function of SWCNT concentration in the solution. The absorption coefficient of the polymer was found to be unaffected upto a SWCNT concentration 5% w/w. However a minor decrease in the absorption in visible region was observed for higher SWCNT concentrations. The intensity of PL emission from the composite was measured and was found to decrease with the increase in SWCNT concentration. For a SWCNT concentration of 30% w/w, ∼90% of the PL was quenched, indicating an ultra fast transfer of photoinduced charges from donor polymer to acceptor SWCNT. Direct current conductivity of the composite film was found to increase rapidly with the increase in SWCNT concentration and an increase of ∼5 orders of magnitude was observed for a 30% w/w concentration. The enhancement in conductivity is explained in terms of percolation theory with an estimated percolation threshold of 2% w/w.     

Conducting polymer embedded with nanoferrite and titanium dioxide nanoparticles for microwave absorption

The present paper deals with the synthesis of conducting ferrimagnetic polyaniline nanocomposite embedded with γ-Fe₂O₃ (9–12 nm) and titanium dioxide (70–90 nm) nanoparticles via a micro-emulsion polymerization. The microwave absorption properties of nanocomposite in 12.4–18 GHz (Ku-band) frequency range shows shielding effectiveness due to absorption (SE_A) value of ?45 dB, which is much higher than polyaniline composite with iron oxide and polyaniline–TiO₂ composites. The higher EMI shielding is mainly arising due to combined effect of γ-Fe₂O₃ and TiO₂ that leads to more dielectric and magnetic losses which consequently contributed to higher values of shielding effectiveness. XRD analysis of the nanocomposite reveals the incorporation of nanoparticles in the conducting polymer matrix while the thermal gravimetric analysis (TGA) demonstrates that the nanocomposite is stable up to 250 °C.     

Structure and stability of the B2 phase in Ti–25Al–25Zr alloy

This paper reports the formation of an ordered B2 phase in the alloy Ti–25Al–25Zr. The structure of the B2 phase has been confirmed by X-ray diffraction and transmission electron microscopic techniques. The B2 phase transforms to two phases (Ti₂AlZr and Al₃Zr₅) and an orthorhombic phase during aging and mechanical polishing, respectively. The instability of B2 phase has been attributed to higher heat of formation of the B2 phase than that of Ti₂AlZr (D0₁₉) structure.     

A dam-breach erosion model: II. Application

In Part I, the earthen dam breach erosion was analyzed. To this end, the BEED (breach erosion of earthfill dams) model was modified and extended. In this paper, Part II of the series, the extended BEED model is applied to three historical cases: South Fork Dam, Buffalo Creek Dam, and Teton Dam. The testing before it can be used for forecast purposes. A sensitivity analysis of the model to its parameters shows that the model is very sensitive to friction factors; Chenzy's for breach erosion, and Manning's for flood routing.     

Propagation Characteristics of an Elliptically-cored Highly Birefringent Fiber using an Analytical Method

By using the method of separation of variables in the elliptical coordinate system, a representative formula in terms of Mathieu and modified Mathieu functions is derived and longitudinal field components for the even and odd modes are presented for the proposed fiber. The eigen value equation for the fiber to be considered is obtained by solving the fourth order determinantal equation under weak guidance condition and is given in this paper. The cutoff frequency of several lower orders modes for different eccentricities have been obtained and their propagation characteristics have been plotted. The effect of the eccentricity on the modal cutoff values and mode transmissions is discussed. Finally, the modal birefringence in the proposed fiber is also estimated.     

Identifying axial load patterns using space frame FEMs and measured vibration data

The axial loading of a space frame may need to be quantified, perhaps for improvement of a finite element model (FEM) to better represent the structural dynamics or to ascertain how close the structure is to buckling. The coexistence of compressive and tensile forces in a space frame causes certain frequencies to increase with respect to load while others decrease. This intricate behaviour has been modelled in the FEM of a bi-tetrahedral space frame through consideration of the geometric stiffness, which accounts for stiffness changes in the loaded members. Updating the load pattern in the FEM using Newton's method (traditional sensitivity-based model updating) brings the model frequencies closer to those physically measured from the real bi-tetrahedral frame and thus provides identification of the axial loads. This load pattern is a predetermined set of frame axial forces in equilibrium. Such a constraint means that the extent of loading can be described by just one scalar updating parameter, an improvement upon former methods that updated member forces as independent parameters. When compared to the loads measured using strain gauges, the loads identified by model updating are seen to offer approximations of the actual loading. Difficulties such as modelling joint behaviour are discussed. The present work extends a series of numerical studies on load updating published by the authors by offering a demonstration of load pattern identification using physically measured vibration data from a real space frame.     

Electrochemical evaluation of the synergistic effect of molybdate tungstate inhibitor mixtures in chloride ion medium and effect of Cl− ion on inhibition efficiency of molybdate

It is well known to corrosion community about chromates and nitrates which are widely used as corrosion inhibitors. However, it is also well known that these inhibitors are oxidizing inhibitors of which chromates are carcinogenic also. Therefore, use of non toxic inhibitors such as molybdate and tungstate are gaining importance. AC impedance analysis of mild steel panels exposed to 3% NaCl containing 6000 ppm molybdate, 5000 ppm molybdate + 1000 ppm tungstate, 3000 ppm molybdate + 3000 ppm tungstate, 1000 ppm molybdate + 5000 ppm tungstate, 6000 ppm tungstate were evaluated. The impedance studies were carried out for different durations viz. 1 hour, 1 day and 7 days. From impedance analysis, it is clear that molybdate and tungstate are not forming any promising synergistic mixtures. The effect of chloride ion concentration viz. 0.01M, 0.05M, 0.1M, 0.3M and 0.6M on inhibition efficiency of molybdate has been discussed. Addition of small amount of tungstate along with molybdate enhances long term film stability on mild steel. It has been found that the inhibition effect is decreasing with increase in concentration up to 0.1M and on further increase in concentration viz. 0.3M and 0.6M, an increase in inhibition efficiency was observed. It has been found that deaeration negatively affected the film properties and did not form a stable film. The corrosion products formed were analyzed using Mössbauer spectroscopy and FT-IR spectroscopy, which showed the presence of oxyhydroxides.     

CSCC for the mean and standard deviation of non-normally distributed life test data

In this paper Cumulative Sum Control Charts (CSCC) have been constructed for the mean and standard deviation of non-normally distributed life test data. The parameters of the V-mask have been determined and finally the expression for the Average Run Length is derived.