Optimization of Procedures for In-Line Extraction of Lipids and Polyphenols from Grape Seeds

Grape seeds (Vitis vinifera L.), a type of raw material containing around 20 % (w/w) of lipids and 20 % (w/w) of phenolic compounds in dry weight, are the main by-products in wine industry. In this work, water and hydroalcoholic mixtures have been first investigated to obtain the optimal solvent for further extractions. Polyphenols and lipids were then extracted by three combined extraction procedures to compare their effectiveness so that the optimal procedure was determined. The results showed that the best yield was achieved by the in-line combination of maceration before grinding and followed by Soxhlet extraction using aqueous ethanol (ethanol/water, 80:20 v/v) at 80 °C.     

Regulation of flexible structures via nonlinear coupling

In this article, we propose an active/passive vibration controller for a cantilever beam using a sliding mass-spring-dashpot mechanism. The controller is placed at the free end of the beam, introducing Coriolis, inertia, and centripetal nonlinearities into the system, resulting in nonlinear coupling that may be used to quench the transient vibration of the beam. When the natural frequency of the slider is twice the fundamental beam frequency (2:1 internal resonance), the two systems will be coupled through nonlinearities that cause the oscillatory energy to be transferred back and forth between the beam and the slider. Control is achieved once the vibration of the beam is absorbed by the slider and dissipated through the slider damping. Numerical results show that this technique can improve the effective damping ratio of the structure by a factor of 15. This technique is particularly useful for reducing large-amplitude oscillations to levels that may be managed using conventional methods.Due to the nonlinearities in the system, for small or zero controller damping, chaotic transient oscillations can occur depending on the amplitude of the initial disturbance of the beam. Editor: T. Vincent     

Performance comparison of different decoding strategies for abandwidth-efficient block-coded scheme on mobile radio channels

The performance of bandwidth-efficient Reed-Solomon (RS)-coded MPSK schemes is evaluated on a shadowed Rician fading channel using different decoding strategies, namely, errors-only, errors-and-erasures, and soft-decision decoding. The lower bounds of the bit error probability are found for errors-only and for errors-and-erasures decoding. For the soft-decision decoding the upper bound of the bit error rate is derived. The error bounds are calculated and examined by simulation for some RS-coded MPSK schemes on a shadowed Rician channel. It is shown that their performance is significantly improved compared to uncoded QPSK. The amount of improvement depends on the signal-to-noise ratio (SNR), the decoding strategy, and the degree of shadowing. A comparison between different decoding techniques, for one of the RS-coded schemes, for different degrees of shadowing shows that the use of channel measurement information in the decoding process is more effective for heavy shadowed channels     

Long-term effect of forskolin on the activation of adenylyl cyclase in astrocytes

Long-term (48-h) forskolin treatment of rat astroglial cells led to a slight decrease (30-40%) in the response to isoproterenol, vasoactive-intestinal peptide, guanyl 5'-(beta gamma-imido)diphosphate, guanosine 5'-O-(3-thiotriphosphate) [GTP(S)], and AIF4- in crude membrane fractions. In contrast, the acute stimulatory effect of forskolin was increased by 1.25-1.5-fold. These two opposite effects of forskolin were mediated by a cyclic AMP-dependent mechanism. No changes in Gs alpha, Gi alpha, or G beta protein levels could be determined by immunoblotting using specific antisera. No significant differences were observed in the ability of G proteins extracted from control and forskolin-treated cells to reconstitute a full adenylyl cyclase activity in membranes from S49 cyc- cells, lacking Gs alpha protein. Gs alpha proteins were detected in two pools of membranes, one in the heavy sucrose fractions and the other in light sucrose fractions. Forskolin treatment of the cells shifted Gs alpha protein toward the light-density membranes. We did not find any significant change in the distribution of adenylyl cyclase. In contrast to the decreased stimulation of adenylyl cyclase activity by agonists acting via Gs alpha, observed in the crude membrane fraction, the responses of adenylyl cyclase to forskolin as well as to GTP(S) were increased in the purified plasma membrane fractions. These results may indicate that sensitization of the catalyst appears to be the dominant component in the astroglial cell response to long-term treatment by forskolin.     

Studies on the thermoelectric effect in semiconducting MnO<Subscript>2</Subscript> thin films

The thermoelectric power of MnO₂ thin films prepared by pyrolytic technique has been measured from room temperature up to 423 K with reference to pure lead. The thickness and temperature dependence of its related parameters have been studied. The Fermi levels were determined using a non-degenerate semiconducting model. The carrier scattering index, activation energy and temperature coefficient of activation energy have all been obtained at different ranges of thickness and temperature. All the samples were optically transparent and polycrystalline in structure.     

Production of high carbon ferromanganese using manganese rich slag in the charge

The possibility of replacement of the high cost sinter manganese ore by manganese rich slag for the production of high carbon ferromanganese was experimentally demonstrated. The experimental heats were designed and carried out to optimize this replacement through the adjustment of different production parameters. The results of pilot plant experimental heats showed that replacement of 50% of the sinter in the blend (or 25% of the blend) by slag containing 32% Mn and operation under slag basicity 0.9 and low (MgO)/(CaO) ratio of about 0.2-0.3 are the optimum conditions to attain the highest manganese content in the produced ferromanganese, the highest manganese recovery and the highest metallic yield. The industrial application of reusing manganese slag clarified the economic efficiency of charging manganese slag up to 20-25% of the blend in reducing the production cost due to reducing the cost of manganese ores. Charging of 20-25% manganese slag reduces the cost of manganese ores and the total production cost by about 13 and 6% respectively, comparing with the conventional technology (without using manganese slag in the blend).     

Compositional inhomogeneity at the epitaxial layer and substrate interface of AlGaAs/GaAs heterostructures

Carrier concentration spikes at the epilayer/substrate interface were observed in some two-dimensional electron gas AIGaAs/GaAs structures grown by low pressure organometallic vapor phase epitaxy. Using secondary ion mass spectroscopy, the carrier spikes were correlated with indium. Under certain growth conditions an anomalous interfacial layer, which is compositionally inhomogeneous, is formed producing an enhanced carrier density. Procedures are described which reduce the presence of indium at the epilayer/substrate interface and eliminate the carrier spike.     

High-performance liquid chromatographic assay for fenoprofen in human plasma

A high-performance liquid chromatographic method is described for the quantitation of fenoprofen, dl-2-(3-phenoxyphenyl)-propionic acid, in human plasma. The proteins in plasma were precipitated by the addition of hydrochloric acid. Fenoprofen and the internal standard, dl-2-(4-phenoxyphenyl)valeric acid, were extracted into butyl chloride and then back-extracted into sodium hydroxide. The aqueous solution was injected onto a reversed-phase alkylphenyl column, and the compounds were eluted using a mobile phase of acetonitrile-water-acetic acid (50:50:2 v/v/v). At a flow rate of 1 ml/min, the retention times of fenoprofen and the internal standard were 8 and 12 min, respectively. The absorbance was monitored at 272 nm. The method requires 1.0 ml of plasma and is sensitive to 0.5 microgram/ml. This procedure has been used for routine assay of multiple samples from bioavailability and compliance studies.