Active sound quality control of engine induced cavity noise

Active control solutions appear to be a feasible approach to cope with the steadily increasing requirements for noise reduction in the transportation industry. Active controllers tend to be designed with a target on the sound pressure level reduction. However, the perceived control efficiency for the occupants can be more accurately assessed if psychoacoustic metrics can be taken into account. Therefore, this paper aims to evaluate, numerically and experimentally, the effect of a feedback controller on the sound quality of a vehicle mockup excited with engine noise. The proposed simulation scheme is described and experimentally validated. The engine excitation is provided by a sound quality equivalent engine simulator, running on a real-time platform that delivers harmonic excitation in function of the driving condition. The controller performance is evaluated in terms of specific loudness and roughness. It is shown that the use of a quite simple control strategy, such as a velocity feedback, can result in satisfactory loudness reduction with slightly spread roughness, improving the overall perception of the engine sound. (C) 2008 Elsevier Ltd. All rights reserved.

A state-space modeling approach for active structural acoustic control

The demands for improvement in sound quality and reduction of noise generated by vehicles are constantly increasing, as well as the penalties for space and weight of the control solutions. A promising approach to cope with this challenge is the use of active structural-acoustic control. Usually, the low frequency noise is transmitted into the vehicle`s cabin through structural paths, which raises the necessity of dealing with vibro-acoustic models. This kind of models should allow the inclusion of sensors and actuators models, if accurate performance indexes are to be accessed. The challenge thus resides in deriving reasonable sized models that integrate structural, acoustic, electrical components and the controller algorithm. The advantages of adequate active control simulation strategies relies on the cost and time reduction in the development phase. Therefore, the aim of this paper is to present a methodology for simulating vibro-acoustic systems including this coupled model in a closed loop control simulation framework that also takes into account the interaction between the system and the control sensors/actuators. It is shown that neglecting the sensor/actuator dynamics can lead to inaccurate performance predictions.

Experimental analysis of active-passive vibration control using viscoelastic materials and extension and shear piezoelectric actuators

Hybrid active-passive damping treatments combine the reliability, low cost and robustness of viscoelastic damping treatments and the high-performance, modal selective and adaptive piezoelectric active control. Numerous hybrid damping treatments have been reported in the literature. They differ mainly by the relative positions of viscoelastic treatments, sensors and piezoelectric actuators. In this work we present an experimental analysis of three active-passive damping design configurations applied to a cantilever beam. In particular, two design configurations based on the extension mode of piezoelectric actuators combined with viscoelastic constrained layer damping treatments and one design configuration with shear piezoelectric actuators embedded in a sandwich beam with viscoelastic core are analyzed. For comparison purposes, a purely active design configuration with an extension piezoelectric actuator bonded to an elastic beam is also analyzed. The active-passive damping performance of the four design configurations is compared. Results show that active-passive design configurations provide more reliable and wider-range damping performance than the purely active configuration.

Failure Mechanisms in Sand over a Deep Active Trapdoor

An experimental testing program was undertaken to investigate failure mechanisms induced by the active movement of a deep rectangular trapdoor underlying a granular soil. Reduced-scale models were tested under normal gravity as well as under an increased gravitational field using a centrifuge facility. Some models were used to evaluate the performance of both flexible and rigid pipes undergoing a localized loss of support. Failure mechanisms in the longitudinal direction of the models were characterized by a single, well-defined failure surface that developed within the limits of the trapdoor. However, failure mechanisms in the transverse direction of the models were characterized by multiple failure surfaces extending outside the limits of the trapdoor. Significant dilation of the soil located immediately above the trapdoor was identified in the failure of the models. The pattern of the failure mechanisms was found to be affected by the stress level and backfill density. Higher stress levels were found to lead to well-developed failure zones. The influence of backfill density was found to be more relevant in models involving flexible pipes. Pipes embedded within loose backfill were severely damaged after loss of support, while pipes embedded in dense backfill experienced negligible deformations. These results indicate that damage to pipelines caused by ground loss of support can be significantly minimized by controlling the compaction of the fill.

Secondary metabolites produced by Propionicimonas sp (ENT-18) induce histological abnormalities in the sclerotia of Sclerotinia sclerotiorum

Sclerotinia sclerotiorum is a highly aggressive pathogen that causes great economic losses, especially in temperate climates. Several biological control agents are available, but actinobacteria have seldom been used to control this fungus. Our objective was to evaluate the efficiency and ultrastructural effects of the secondary metabolites produced by the ant-associated actinobacterium Propionicimonas sp. ENT-18 in controlling the sclerotia of S. sclerotiorum. We demonstrated total inhibition of sclerotia treated with 62.5 mu g/10 mu l of an ethyl acetate extract of compounds produced by ENT-18, and calculated an LC(50) of 1.69 mu g/sclerotia. Histological and ultrastructural analysis indicated that the cells of the treated sclerotia were severely damaged, suggesting direct action of the biomolecule(s) produced by the actinobacterium ENT-18 on the cell structure of the medullae and rind cell wall. This is the first report demonstrating a novel property of Propionicimonas sp.-antifungal activity against S. sclerotiorum.

Changes in the hemolymph and fat body metabolites of Diatraea saccharalis (Fabricius) (Lepidoptera : Crambidae) parasitized by Cotesia flavipes (Cameron) (Hymenoptera : Braconidae)

The koinobiont Cotesia flavipes responds to and is influenced by biochemical changes in the host hemolymph composition, Diatraea saccharalis. Changes in the composition of macronutrients may occur due to the hosts own development or by changes induced after parasitization. These changes occur to facilitate parasitoid invasion and to make the host internal environment suitable to parasitoid immature development. Therefore, changes in the availability of stored and circulating nutrients may correlate with the nutritional requirements of specific parasitoid immature stages. In here, we describe changes in the biochemical composition of parasitized and control larvae at different stages of parasitoid development to gain information on C flavipes host regulation and on its quantitative immature nutritional requirements. Total proteins, lipids and carbohydrates free in the hemolymph or stored in host fat bodies, and the SDS-PAGE protein profile of the hemolymph were evaluated in control and parasitized 6th instar during the whole parasitoid development. Changes in the total protein available in the host hemolymph were detected soon after parasitization, but carbohydrate and lipids were observed to differ only towards parasitoid larvae egression. Although C. flavipes affected the availability of all macronutrients observed in the host hemolymph, lipids and proteins stored in the host fat bodies were unaffected. However, carbohydrate concentration at the end of parasitoid larval development was much lower in parasitized than in control larvae at the same stage of development. SDS-PAGE analysis indicated C flavipes up-regulated two host proteins (125 and 48 kDa) and released two parasitism-specific proteins towards the end of parasitoid larval development. We provide a discussion on the role these changes may have on the process of host regulation and their possible requirement to sustain parasitoid development. (C) 2007 Elsevier Inc. All rights reserved.

Body weight as an indicator of fat-free mass in active elderly women

Objective: Fat-free mass (FFM) reduction and the tendency for a reduction in surrounding fatty issue and increase in the middle are a natural consequence of growing old and should be studied in order to gain a better understanding of the aging process. This study set out to find the FFM differences between active elderly women in two age groups (60-69 and 70-80 years) and to determine which of the anthropometric measurements, body weight (BW), abdominal circumference (AC), or body mass index (BMI) are the best predictors of FFM variation within the group. Methods: Eighty-one (n = 81) active elderly women of the Third Age willingly signed up to participate in the research during the activities at the University of the Third Age (UTA) in Brazil. The research was approved by the Research Ethics Committee of the Faculty of Medical Sciences of the State University of Campinas (UNICAMP). Body weight (BW), height (H) and the BMI were measured according to the international standards. The AC was measured in centimetres at the H of the navel and body composition was ascertained using bioimpedance analysis. The SAS program was used to perform the statistical analysis of independent samples and parametric data. Results: The results showed FFM values with significant differences between the two groups, with the lowest values occurring among the women who were over 70 years of age. In the analysis, the Pearson`s Correlation Coefficient for each measured independent variable was ascertained, with the BW measurement showing the highest ratio (0.900). Conclusions: The BW measurement was regarded as reliable, low-cost and easy to use for monitoring FFM in elderly women who engage in physical activities. (C) 2011 Elsevier Ireland Ltd. All rights reserved.

Growth-active gibberellins overcome the very slow shoot growth of Hancornia speciosa, an important fruit tree from the Brazilian ""Cerrado""

Shoot elongation of Hancornia speciosa, an endangered tree from the Brazilian savannah ""Cerrado"", is very slow, thus limiting nursery production of plants. Gibberellins (GAs) A(1), A(3), and A(5), and two inhibitors of GA biosynthesis, trinexapac-ethyl and ancymidol were applied to shoots of Hancornia seedlings. GA(1) and GA(3) significantly stimulated shoot elongation, while GA(5) had no significant effect. Trinexapac-ethyl and ancymidol, both at 100 A mu g per seedling, inhibited shoot elongation up to 45 days after treatment, though the effect was statistically significant only for ancymidol. Somewhat surprisingly, exogenous GA(3) more effectively stimulated shoot elongation in SD-grown plants, than in LD-grown plants. The results from exogenous application of GAs and inhibitors of GA biosynthesis imply that Hancornia shoot growth is controlled by GAs, and that level of endogenous growth-active GAs is likely to be the limiting factor for shoot elongation in Hancornia. Application of GAs thus offer a practical method for nursery production of Hancornia seedlings for outplanting into the field.

Synergism between lipoxygenase-active soybean flour and ascorbic acid on rheological and sensory properties of wheat bread

BACKGROUND: The interaction between lipoxygenase-active soybean flour (LOX) and ascorbic acid (AA), on colour, rheological and sensory properties of wheat bread was studied with the aim of reducing the applied quantity of additives in bread formulations. RESULTS: The ascorbic acid (0-500 ppm) and active soybean flour (0-1%) mixture improved bread-crumb colour by lowering the yellow hue in a higher proportion than those expressed by the components alone, characterising a synergistic mechanism ((y) over cap (b) = 15.1- (1.7 x LOX) - (0.5 x AA) - (5.8 x LOX x AA), where : (y) over cap (b) represent the estimated value for the yellow hue parameter). No differences in flavour and porosity were seen between the samples. As supported by the instrumental methods, breads made with active soybean flour and ascorbic acid (LOX + AA) had whiter crumbs and were softer and springier than controls as assessed by a trained sensory panel. In summary, the combination of both active soybean flour and ascorbic acid showed synergism, promoting a greater bleaching effect than when used alone. CONCLUSION: These results suggest the potential use of active soybean flour as a synergistic ingredient in the substitution of artificial additives in bread making. Since the interaction on the bleaching response was not linear and active soybean flour showed a higher iron concentration (66.40 +/- 4.23 mu g g(-1)) than non-active soybean flour (52.30 +/- 0.40 mu g g(-1)), more studies are warranted to establish the biochemical mechanisms involved in this interaction. (c) 2007 Society of Chemical Industry.

Relationships between gene polymorphisms of folate-related proteins and vitamins and metabolites in pregnant women and neonates

Background: The methylenetetrahydrofolate reductase (MTHFR), glutamate carboxypeptidase II (GCPII) and reduced folate carrier (RFC1) gene polymorphisms were associated with folate status. We investigated the effects of these polymorphisms on serum folate (SF) and folate-related metabolites in mothers and their neonates. Methods: Cobalamin (Cbl), SF, total homocysteine (tHcy), methylmalonic acid (MMA), S-adenosylmethionine (SAM), and S-adenosylhomocysteine (SAH) were measured in 275 healthy women and their neonates. MTHFR C677T, GCPII C1561T and RFC1 A80G polymorphisms were determined by PCR-RFLP. Results: Maternal tHcy was affected individually by MTHFR C677T and GCPII C1561T polymorphisms and by combined genotypes MTHFR 677TT/GCPII 1561CC and MTHFR 677TT/RFC1 80AG. The MTHFR and RFC1 polymorphisms were not associated with variations in vitamins or SAM, SAH and MMA in neonates. Neonatal tHcy was predicted directly by maternal tHcy and inversely by maternal SF, neonatal Cbl and neonatal RFC1 80G allele (AG+GG genotypes). Maternal MMA and SAM/SAH were predicted by creatinine and Cbl, respectively. Neonatal MMA was predicted by maternal MMA and GCPII 1561T allele (CT+TT genotypes) and by neonatal Cbl. Conclusions: Maternal tHcy was affected by MTHFR C677T, RFC1 A80G and GCPII C1561T polymorphisms. Maternal GCPII C1561T variant was associated with neonatal MMA. Neonatal RFC1 A80G polymorphism influenced tHcy in neonates. (C) 2008 Elsevier B.V. All rights reserved.

Development of a Stability-Indicating LC Assay Method for Determination of Chloroquine

A simple and rapid development of a stability-indicating LC method for determination of chloroquine diphosphate in the presence of its hydrolysis, oxidative and photolysis degradation products is described. Stress testing showed that chloroquine diphosphate was degraded under basic conditions and by photolytic treatment but was stable under the other stress conditions investigated. Separation of the drug from its degradation products was achieved with a Nova Pack C18 column, 0.01 M PIC B7 and acetonitrile (40:60 v/v) pH 3.6, as mobile phase. Response was linear over the range 0.08-5.70 mu g mL(-1) (r = 0.996), with limits of detection and quantification (LOD and LOQ) of 0.17 and 0.35 mu g mL(-1), respectively.

Evaluation of gastroprotective activity of Plinia edulis (Vell.) Sobral (Myrtaceae) leaves in rats

Plinia edulis, an arboreous species popularly known as ""cambuca"", is native to the Brazilian Atlantic Rain Forest. Despite its traditional uses, no reports are available on the safety of this utilization or on the relationship between the antiulcer activity of its extract and its phytochemical compounds. This paper reports on the investigation of the acute toxicity and gastroprotective effect of the aqueous ethanol extract of leaves of Plinia edulis on HCl/ethanol-induced ulcers. In order to correlate the secondary metabolites and the efficacy of the crude drug in traditional medicine, the extract was submitted to chromatographic fractionation after solvent partition. The extract did not show acute toxicity in mice treated with 5 g/kg p.o.. but exhibited significant antiulcer activity in rats at doses of 100, 200, and 400 mg/kg p.o., more active than the reference drug lansoprazole. The ethyl acetate fraction yielded P-amyrin, oleanolic acid, ursolic acid, and maslinic acid, which were identified based on spectrometric analyses. Since antiulcerogenic activity is not restricted to one class of compounds in plants, the triterpenoids isolated in the extract can be associated with the observed effect. (C) 2008 Elsevier Ireland Ltd. All rights reserved.

Generation and Analysis of Interaction Energy Maps of p-Substituted Benzoic Acid [(5-Nitro-thiophen-2-yl)-methylene]-Hydrazides Active against MRSA

In this preliminary study eighteen p-substituted benzoic acid [(5-nitro-thiophen-2-yl)-methylene]-hydrazides with antimicrobial activity were evaluated against multidrug-resistant Staphylococcus aureus, correlating the three-dimensional characteristics of the ligands with their respective bioactivities. The computer programs Sybyl and CORINA were used, respectively, for the design and three-dimensional conversion of the ligands. Molecular interaction fields were calculated using GRID program. Calculations using Volsurf resulted in a statistically consistent model with 48 structural descriptors showing that hydrophobicity is a fundamental property in the analyzed biological response.

In vitro characterization of rosiglitazone metabolites and determination of the kinetic parameters employing rat liver microsomal fraction

Rosiglitazone (RSG), a thiazolidinedione antidiabetic drug, is metabolized by CYP450 enzymes into two main metabolites: N-desmethyl rosiglitazone (N-Dm-R) and rho-hydroxy rosiglitazone (rho-OH-R). In humans, CYP2C8 appears to have a major role in RSG metabolism. On the other hand, the in vitro metabolism of RSG in animals has not been described in literature yet. Based on these concerns, the kinetic metabolism study of RSG using rat liver microsomal fraction is described for the first time. Maximum velocity (V (max)) values of 87.29 and 51.09 nmol/min/mg protein were observed for N-Dm-R and rho-OH-R, respectively. Michaelis-Menten constant (K (m)) values were of 58.12 and 78.52 mu M for N-Dm-R and rho-OH-R, respectively. Therefore, these results demonstrated that this in vitro metabolism model presents the capacity of forming higher levels of N-Dm-R than of rho-OH-R, which also happens in humans. Three other metabolites were identified employing mass spectrometry detection under positive electrospray ionization: ortho-hydroxy-rosiglitazone (omicron-OH-R) and two isomers of N-desmethyl hydroxy-rosiglitazone. These metabolites have also been observed in humans. The results observed in this study indicate that rats could be a satisfactory model for RSG metabolism.

Antileukemic effects of Didemnum psammatodes (Tunicata: Ascidiacea) constituents

Chemical investigation of the methanolic extract of the ascidian Didemnum psammatodes has led to the identification of fourteen known compounds: three methyl esters (methyl myristate, methyl palmitate and methyl stearate), four steroids (cholesterol, campesterol, stigmasterol and beta-sitosterol), two fatty acids (palmitic acid and stearic acid), three glyceryl ethers {(1,2-propanediol, 3-(heptadecyloxy), batyl alcohol and 1,2-propanediol, 3-[(methyloctadecyl)oxy]) and two nucleosides (thymidine and 2`-deoxyguanosine). Their structures were proposed by NMR and comparison with literature data and GC analysis in comparison with authentic sample. The cytotoxic activity of these compounds was evaluated against human leukemia cell line panel using the MTT assay. The mixture of the three methyl esters was the most active group of compounds, showing antiproliferative and cytotoxic effects. Further studies on their mode of action suggest that these activities are connected with inhibition of DNA synthesis and induction of both necrosis and apoptosis. (C) 2007 Elsevier Inc. All rights reserved.