Macro-Fiber Composite Actuators for Flow Control of a Variable Camber Airfoil

This research employs solid-state actuators for delay of flow separation seen in airfoils at low Reynolds numbers. The flow control technique investigated here is aimed for a variable camber airfoil that employs two active surfaces and a single four-bar (box) mechanism as the internal structure. To reduce separation, periodic excitation to the flow around the leading edge of the airfoil is induced by a total of nine piezocomposite actuated clamped-free unimorph benders distributed in the spanwise direction. An electromechanical model is employed to design an actuator capable of high deformations at the desired frequency for lift improvement at post-stall angles. The optimum spanwise distribution of excitation for increasing lift coefficient is identified experimentally in the wind tunnel. A 3D (non-uniform) excitation distribution achieved higher lift enhancement in the post-stall region with lower power consumption when compared to the 2D (uniform) excitation distribution. A lift coefficient increase of 18.4% is achieved with the identified non-uniform excitation mode at the bender resonance frequency of 125 Hz, the flow velocity of 5 m/s and at the reduced frequency of 3.78. The maximum lift (Clmax) is increased 5.2% from the baseline. The total power consumption of the flow control technique is 639 mW(RMS).

Piezoceramic Composite Actuators for Flow Control in Low Reynolds Number Airflow

The research presented here employs solid-state actuators for flow separation delay or for forced attachment of separated flow seen in airfoils at low Reynolds numbers. To reduce separation, periodic excitation to the flow around the leading edge of the airfoil is induced by Macro-Fiber Composite actuated clamped-free unimorph benders. An electromechanical model of the unimorph is briefly presented and parametric study is conducted to aid the design of a unimorph to output high deformation at a desired frequency. The optimum frequency and amplitude for lift improvement at post-stall angles are identified experimentally. Along with aerodynamic force and structural displacement measurements, helium bubble flow visualization is used to verify existing separated flow, and the attached flow induced by flow control. The lift enhancement induced by several flow control techniques is compared. A symmetric and non-uniform (3D) flow excitation results in the maximum lift enhancement at post-stall region at the lowest power consumption level. A maximum lift coefficient increase of 27.5% (in the post-stall region) is achieved at 125 Hz periodic excitation, with the 3D symmetric actuation mode at 5 m/s and the reduced frequency of 3.78. C(l,max) is increased 7.6% from the baseline.

Feasibility of Electronic Tap-Changing Stabilizers for Medium Voltage Lines-Precedents and New Configurations

Thyristor-based onload tap-changing ac voltage stabilizers are cheap and robust. They have replaced most mechanical tap-changers in low voltage applications from 300 VA to 300 M. Nevertheless, this replacement hardily applies to tap-changers associated to transformers feeding medium-voltage lines (typically 69 kV primary, 34.5 kV line, 10 MVA) which need periodical maintenance of contacts and oil. The Electric Power Research Institute (EPRI) has studied the feasibility of this replacement. It detected economical problems derived from the need for series association of thyristors to manage the high voltages involved, and from the current overload developed under line fault. The paper reviews the configurations used in that field and proposes new solutions, using a compensating transformer in the main circuit and multi-winding coils in the commutating circuit, with reduced overload effect and no series association of thyristors, drastically decreasing their number and rating. The stabilizer can be installed at any point of the line and the electronic circuit can be fixed to ground. Subsequent works study and synthesize several commutating circuits in detail.

Cement stabilization of runoff residuals: A study of stabilization/solidification of urban rainfall-runoff residuals in type 1 Portland cement by XRD and Si-29 NMR analysis

Urban rainfall-runoff residuals contain metals such as Cr, Zn, Cu, As, Pb and Cd and are thus reasonable candidates for treatment using Portland cement-based solidification-stabilization (S/S). This research is a study of S/S of urban storm water runoff solid residuals in Portland cement with quicklime and sodium bentonite additives. The solidified residuals were analyzed after 28 days of hydration time using X-ray powder diffraction (XRD) and solid-state Si-29 nuclear magnetic resonance (NMR) spectroscopy. X-ray diffraction (XRD) results indicate that the main cement hydration products are ettringite, calcium hydroxide and hydrated calcium silicates. Zinc hydroxide and lead and zinc silicates are also present due to the reactions of the waste compounds with the cement and its hydration products. Si-29 NMR analysis shows that the coarse fraction of the waste apparently does not interfere with cement hydration, but the fine fraction retards silica polymerization.

Ipolamiide and fulvoipolarniide from Stachytarpheta glabra (Verbenaceae): A structural and spectroscopic characterization

The phenylethanoid glycoside acteoside and the iridoids ipolamiide and 4-methoxycarbonyl-7-methylcyclopenta[c]pyran (fulvoipolamiide) were isolated from the leaves of Stachytarpheta glabra. The solid state structure of fulvoipolamiide was confirmed by X-ray diffraction studies. The molecules of fulvoipolamiide are displayed in layers parallel to the crystallographic axis a. This molecule is planar with electron delocalization in the fused ring system and the pyran rings of adjacent layers in the solid state structure are involved in a pi-pi stacking interaction. Raman spectroscopy has also been used to characterize the most important bands present in the spectra of fulvoipolamiide and ipolamiide, and comparison made with literature allows the assignment of some key markers, specially the bands in the 1600-1700 cm(-1) range. (C) 2007 Elsevier B.V. All rights reserved.

Biochemical and Functional Characterization of a Metalloprotease from the Thermophilic Fungus Thermoascus aurantiacus

Protease production was carried out in solid state fermentation. The enzyme was purified through precipitation with ethanol at 72% followed by chromatographies in columns of Sephadex G75 and Sephacryl S100. It was purified 80-fold and exhibited recovery of total activity of 0.4%. SDS-PAGE analysis indicated an estimated molecular mass of 24.5 kDa and the N-terminal sequence of the first 22 residues was APYSGYQCSMQLCLTCALMNCA. Purified protease was only inhibited by EDTA (96.7%) and stimulated by Fe(2+) revealing to be a metalloprotease activated by iron. Optimum pH was 5.5, optimum temperature was 75 degrees C, and it was thermostable at 65 degrees C for 1 h maintaining more than 70% of original activity. Through enzyme kinetic studies, protease better hydrolyzed casein than azocasein. The screening of fluorescence resonance energy transfer (FRET) peptide series derived from Abz-KLXSSKQ-EDDnp revealed that the enzyme exhibited preference for Arg in P(1) (k(cat)/K(m) = 30.1 mM(-1) s(-1)).

Production and characteristics comparison of crude beta-glucosidases produced by microorganisms Thermoascus aurantiacus e Aureobasidium pullulans in agricultural wastes

The purified beta-glucosidase of Aureobasidium pullulans ER-16 is one of more thermostable enzyme reported to date. Considering the unfeasibility of using purified enzyme for industrial application, it was interesting to analyze this property for the crude enzyme. Thermophilic fungus Thermoascus aurantiacus CBMAI-756 and mesophilic A. pullulans ER-16 were cultivated in different hemicellulosic materials on solid-state cultivation for beta-glucosidase production. Wheat bran was most appropriate for beta-glucosidase production by both microorganisms. T. aurantiacus exhibited maximum enzyme production (7.0 U/ml or 70 U/g) at 48-72 h and A. pullulans a maximum (1.3 U/ml or 13 U/g) at 120 h. Maximum activities were at 75 degrees C with optimum pH at 4.5 and 4.0, for T aurantiacus and A. pullulans, respectively. A. pullulans`s beta-glucosidase was more pH stable (4.5-10.0 against 4.5-8.0) and more thermostable (90% after 1 h at 75 degrees C against 85% after 1 h at 70 degrees C) than the enzyme from the thermophilic T. aurantiacus. The t((1/2)) at 80 degrees C were 50 and 12.5 min for A. pullulans and T. aurantiascus, respectively. These data confirm the high thermostability of crude beta-glucosidase from A. pullulans. Both beta-glucosidases were strongly inhibited by glucose, but ethanol significantly increased the activity of the enzyme from T. aurantiacus. (C) 2008 Elsevier Inc. All rights reserved.

Evidence of thermostable amylolytic activity from Rhizopus microsporus var. rhizopodiformis using wheat bran and corncob as alternative carbon source

Rhizopus microsporus var. rhizopodiformis produced high levels of alpha-amylase and glucoamylase under solid state fermentation, with several agricultural residues, such as wheat bran, cassava flour, sugar cane bagasse, rice straw, corncob and crushed corncob as carbon sources. These materials were humidified with distilled water, tap water, or saline solutions-Segato Rizzatti (SR), Khanna or Vogel. The best substrate for amylase production was wheat bran with SR saline solution (1:2 v/v). Amylolytic activity was still improved (14.3%) with a mixture of wheat bran, corncob, starch and SR saline solution (1:1:0.3:4.6 w/w/w/v). The optimized culture conditions were initial pH 5, at 45 degrees C during 6 days and relative humidity around 76%. The crude extract exhibited temperature and pH optima around 65 degrees C and 4-5, respectively. Amylase activity was fully stable for 1 h at temperatures up to 75 degrees C, and at pH values between 2.5 and 7.5.

Production of beta-fructofuranosidases by Aspergillus niveus using agroindustrial residues as carbon sources: Characterization of an intracellular enzyme accumulated in the presence of glucose

The production of beta-fructofuranosidases by Aspergillus niveus, cultivated under submerged fermentation using agroindustrial residues, was investigated. The highest productivity of beta-fructofuranosidases was obtained in Khanna medium supplemented with sugar cane bagasse as carbon source. Glucose enhanced the production of the intracellular enzyme, whereas that of the extracellular one was decreased. The intracellular beta-fructofuranosidase was a trimeric protein of approximately 141 kDa (gel filtration) with 53.5% carbohydrate content, composed of 57 kDa monomers (SDS-PAGE). The optimum temperature and optimum pH were 60 degrees C and 4.5, respectively. The purified enzyme showed good thermal stability and exhibited a half-life of 53 min at 60 degrees C. beta-Fructofuranosidase activity was slightly activated by Cu(2+), Mn(2+), Mg(2+), and Na(+) at 1 mM concentration. The enzyme hydrolyzed sucrose, raffinose, and inulin, with K(d) values of 5.78 mM, 5.74 mM, and 1.74 mM, respectively. (C) 2008 Elsevier Ltd. All rights reserved.

Synthesis, characterization and electrochemical behavior of the vanadium pentoxide/cetyl pyridinium chloride hybrid material

In situ and ex situ studies concerning the new hybrid material vanadium pentoxide xerogel in the presence of the cationic surfactant cetyl pyridinium chloride (V(2)O(5)/CPC) are presented. The in situ characterization studies revealed the presence of a lamellar structure for the V(2)O(5)/CPC hybrid material. The intercalation reaction was evidenced on the basis of the increase in the d-spacing as well as the displacement of the infrared bands toward lower energy levels. Electrochemical studies comprising the cyclic voltammetry and the electrochemical impedance spectroscopy techniques showed that the behavior of the hybrid material is considerably influenced by the electrolyte composition. The ion insertion/de-insertion into the V(2)O(5) xerogel structure accompanying the charge transfer process is influenced by the solid-state diffusion process modeled by using the finite-space Warburg element.

Production of fibrolytic enzymes by Aspergillus japonicus C03 using agro-industrial residues with potential application as additives in animal feed

Solid-state fermentation obtained from different and low-cost carbon sources was evaluated to endocellulases and endoxylanases production by Aspergillus japonicus C03. Regarding the enzymatic production the highest levels were observed at 30 degrees C, using soy bran added to crushed corncob or wheat bran added to sugarcane bagasse, humidified with salt solutions, and incubated for 3 days (xylanase) or 6 days (cellulase) with 70% relative humidity. Peptone improved the xylanase and cellulase activities in 12 and 29%, respectively. The optimum temperature corresponded to 60 degrees C and 50-55 degrees C for xylanase and cellulase, respectively, both having 4.0 as optimum pH. Xylanase was fully stable up to 40 degrees C, which is close to the rumen temperature. The enzymes were stable in pH 4.0-7.0. Cu(++) and Mn(++) increased xylanase and cellulase activities by 10 and 64%, respectively. A. japonicus C03 xylanase was greatly stable in goat rumen fluid for 4 h during in vivo and in vitro experiments.

In vitro wear, surface roughness and hardness of propanal-containing and diacetyl-containing novel composites and copolymers based on bis-GMA analogs

Objective. To evaluate the effect of two additives, aldehyde or diketone, on the wear, roughness and hardness of bis-GMA-based composites/copolymers containing TEGDMA, propoxylated bis-GMA (CH(3)bis-GMA) or propoxylated fluorinated bis-GMA (CF(3)bis-GMA). Methods. Fifteen experimental composites and 15 corresponding copolymers were prepared combining bis-GMA and TEGDMA, CH3bis-GMA or CF3bis-GMA, with aldehyde (24mol% and 32 mol%) or diketone (24 mol% and 32 mol%) totaling 30 groups. For composites, hybrid treated filler (barium aluminosilicate glass/pyrogenic silica; 60 wt%) was added to monomer mixtures. Photopolymerization was affected by 0.2 wt% each of camphorquinone and N,N-dimethyl-p-toluidine. Wear (W) test was conducted in a toothbrushing abrasion machine (n = 6) and quantified using a profilometer. Surface roughness (R) changes, before and after abrasion test, were determined using a rugosimeter. Microhardness (H) measurements were performed for dry and wet samples using a Knoop microindenter (n = 6). Data were analyzed by one-way ANOVA and Tukey`s test (alpha = 0.05). Results. Incorporation of additives led to improved W and H values for bis-GMA/TEGDMA and bis-GMA/CH(3)bis-GMA systems. Additives had no significant effect on the W and H changes of bis-GMA/CF(3)bis-GMA. With regard to R changes, additives produced decreased values for bis-GMA/CH3bis-GMA and bis-GMA/CF3bis-GMA composites. Bis-GMA/TEGDMA and bis-GMA/CH(3)bis-GMA copolymers with additives became smoother after abrasion test. Significance. The findings correlate with additives ability to improve degree of conversion of some composites/copolymers thereby enhancing mechanical properties. Published by Elsevier Ltd on behalf of Academy of Dental Materials