Forsskamide,a new ceramide from aerial parts of Forsskaolea tenacissima Linn.

Although the various folk medicine uses and the biological activity of Forsskaolea tenacissima L., few chemical constituents of this plant have been reported, this provoked us to make our study. Forsskamide, a new ceramide was isolated from aerial parts of F. tenacissima L. (Urticaceae). The chemical structure was established by different spectroscopic methods (¹H, ¹³C-NMR, HMBC, HSQC, ROESY, FAB-MS and HR-FAB-MS). Forsskamide showed a moderate cytotoxic activity by (MTT) method against human colorectal carcinoma cell line (HCT-116) with IC₅₀ 33.25 μM in comparison with 5-fluorouracil IC₅₀ 26.42 μM. While, it did not show any activity against human hepatocarcinaoma cell line (HepG-2).     

Diode laser absorption measurements at the Hα-transition in laser induced plasmas on different targets

The diode laser atomic absorption spectroscopy (DLAAS) technique has been utilized to assess the degree of optical opacity of plasma at the wavelength of the H_α-line. The plasma is produced at atmospheric conditions by focusing a 6 ns Nd:YAG laser pulse at 1.064 μm on different solid target materials including aluminum, iron and titanium as major elements as well as flat pieces of plastic and wood characterized by a high content of hydrogen. The optical depth was investigated as a function of delay times ranging from 0 to 5 μs, and at laser fluences ranging from 7 to 19 J/cm², all at a fixed gate time of 1 μs. The results show that the plasma associated with metallic targets is almost optically thin at the H_α-line over all fluences and at delay times ≥ 1 μs, but rather thick for hydrogen-rich targets (plastic and wood) over all delay times and fluences.     

2DIR spectroscopy of human amylin fibrils reflects stable β-sheet structure

The aggregation of human amylin to form amyloid contributes to islet β-cell dysfunction in type 2 diabetes. Studies of amyloid formation have been hindered by the low structural resolution or relatively modest time resolution of standard methods. Two-dimensional infrared (2DIR) spectroscopy, with its sensitivity to protein secondary structures and its intrinsic fast time resolution, is capable of capturing structural changes during the aggregation process. Moreover, isotope labeling enables the measurement of residue-specific information. The diagonal line widths of 2DIR spectra contain information about dynamics and structural heterogeneity of the system. We illustrate the power of a combined atomistic molecular dynamics simulation and theoretical and experimental 2DIR approach by analyzing the variation in diagonal line widths of individual amide I modes in a series of labeled samples of amylin amyloid fibrils. The theoretical and experimental 2DIR line widths suggest a "W" pattern, as a function of residue number. We show that large line widths result from substantial structural disorder and that this pattern is indicative of the stable secondary structure of the two β-sheet regions. This work provides a protocol for bridging MD simulation and 2DIR experiments for future aggregation studies.     

Simulations of whistling and the whistling potentiality of an in-duct orifice with linear aeroacoustics

This paper demonstrates a linear aeroacoustic simulation methodology to predict the whistling of an orifice plate in a flow duct. The methodology is based on a linearized Navier–Stokes solver in the frequency domain with the mean flow field taken from a Reynolds-Averaged Navier–Stokes (RANS) solution. The whistling potentiality is investigated via an acoustic energy balance for the in-duct element and good agreement with experimental data is shown. A Nyquist stability criterion based on the simulation data was applied to predict whistling of the orifice when placed in a finite sized duct and experiments were carried out to validate the predictions. The results indicate that although whistling is a nonlinear phenomena caused by an acoustic-flow instability feed-back loop, the linearized Navier–Stokes equations can be used to predict both whistling potentiality and a duct system's ability to whistle or not.     

Vibration control of active vehicle suspension system using fuzzy logic algorithm

Vehicle suspension along with tires and steering linkages is designed for safe vehicle control and to be free of irritating vibrations. Therefore the suspension system designs are a compromise between ride softness and handing ability. However, this work is concerned with a theoretical investigation into the ride behavior of actively suspended vehicles. It is based on using fuzzy logic control (FLC) to implement a new sort of active suspension system. Comparisons between the behavior of active suspension system with FLC with those obtained from active systems with linear-quadratic regulator (LQR), ideal skyhook system and the conventional passive suspension systems. Results are introduced in such a way to predict the benefits that could be achieved from a fuzzy logic system over other competing systems. Furthermore, a controller is designed and made by using results of FLC system, theoretical inputs are used to examine the validity of this controller. Moreover, comparison between actual outputs from this controller with those obtained theoretically is made to judge the validity of the controller. The results indicate that the controller has a good capability in simulation of the theoretical model.     

On the plane deformation of fibre-reinforced viscoelastic plates

The realization method of elastic solutions is used to solve the problem of bending of a viscoelastic plate reinforced unidirectionally by elastic fibres. Numerical computations are carried out for three kinds of external load. The plane deformation of this plate is discussed.     

Stresses of a rotating circular disk of variable thickness carrying a current and bearing a coaxial viscoelastic coating

In the present work we consider a circular elastic disk (conductor) of variable thickness under the influence of a steady coaxial current and bearing a coaxial viscoelastic coating (insulator). In both conductor and insulator there exist a heat source generation. As a first step, the solution of purely elastic conductor and insulator is obtained. Then the problem of model with viscoelastic coating is solved using the correspondence principle and Ilyushin’s approximation method. A numerical example is given and the results are discussed in order to investigate the influences of time, temperature, and rotation on the stresses and displacements.     

Production,Partial Purification,and Biochemical Characterization of a Thermotolerant Alkaline Metallo-protease from Staphylococcus sciuri

Applied Biochemistry and Biotechnology - (R)-[3,5-bis(trifluoromethyl) phenyl] ethanol [(R)-3,5-BTPE] is a crucial chiral intermediate for the synthesis of the NK-1 receptor antagonists aprepitant,...     

Oxidation of trivalent cerium with potassium permanganate in alkaline solutions

Summary Oxidation of trivalent cerium with KMnO₄ in alkaline carbonate mixture is not possible owing to the instability of the solution and to the sluggishness of the reaction. Reduction of KMnO₄ with Ce³⁺ solution fails to give quantitative results in absence of telluric acid. Good results are obtained in presence of telluric acid provided that the alkalinity of the reaction medium is not less than 1 N, in order to overcome the effect of acid present in the cerous solution.A method depending upon the oxidation of Ce³⁺ solution with KMnO₄ followed by back titrating excess KMnO₄ with monovalent thallium gives accurate results.     

Oxidation with manganate solutions

Summary The reaction of tellurite with manganate solution is not rapid in 0.2–0.5 N NaOH but is enhanced at higher alkalinities. Titration of tellurite with manganate gives accurate results. The titration of manganate with quadrivalent tellurium gives good results both in the presence or absence of telluric acid but the accuracy is better in the presence of telluric acid than in its absence. In the titration curve of manganate the step corresponding to hypomanganate is observed only in the presence of telluric acid and above 1 N NaOH.Part I cf. Z. analyt. Chem. 172, 21 (1960).