Predicted effects of fluid loading on the vibration of elastic porous plates

International audienceThe effects of fluid loading on the vibration of rectangular, clamped, porous elastic plates and on their radiated sound power are considered. This requires the inclusion of an extra term in the equations for the plate vibration, corresponding to the additional external force acting on the plate. As is the case for vibrating non-porous plates, fluid-structure coupling is a very complex phenomenon since the plate modes are coupled by the fluid. The radiation impedance matrix, including direct terms and cross-coupling terms, has been defined and computed. A Gaussian quadrature scheme including twenty terms of the Legendre polynomial has been used to compute the fluid loaded plate deflection for four types of porous and elastic plate and compare the effects of the loading by water and air. The corresponding vibroacoustic indicators including mean square velocity, radiated sound power and radiation efficiency, have been calculated also. For some plate and fluid parameters, the predicted effects of fluid loading are considerable

Tracheal Sound Acquisition Using Laser Doppler Vibrometer

Breathing is vital for human life. Respiratory diseases cause more than one million deaths annually. The sound of breathing activity can be used to assess the state of the lungs and detect adverse problems involving respiratory failure. Traditionally, mechanical stethoscopes are used for respiratory auscultation to analyse the lung sounds. Firstly, measurements are carried out on five different standard stethoscopes to assess their reliability for detecting respiratory sounds in people. Secondly, three human subjects were used for tracheal sound experiments using five stethoscopes. Thirdly, a laser doppler vibrometer was used to detect tracheal sounds on three human subjects. Five stethoscopes used for measurements give different results especially above 150 Hz. Experimental results show that mechanical stethoscopes are not reliable tools for assessing lungs sounds in people

Triangular metallic gratings for large absorption enhancement in thin film Si solar cells

Cataloged from PDF version of article.We estimate high optical absorption in silicon thin film photovoltaic devices using triangular corrugations on the back metallic contact. We computationally show 21.9% overall absorptivity in a 100-nm thick silicon layer, exceeding any reported absorptivity using single layer gratings placed on the top or the bottom, considering both transverse electric and transverse magnetic polarizations and a wide spectral range (280 - 1100 nm). We also show that the overall absorptivity of the proposed scheme is relatively insensitive to light polarization and the angle of incidence. We also discuss the implications of potential fabrication process variations on such a device. ©2012 Optical Society of Americ

Serum procalcitonin and cerebrospinal fluid cytokines level in children with meningitis.

AIMS: To determine the level of serum procalcitonin and cerebrospinal fluid cytokines in children with bacterial or viral meningitis and to document the use of these parameters in differential diagnosis. RESULTS: Before the start of antibiotic treatment, serum procalcitonin and tumor necrosis factor alpha levels were found to be higher in acute bacterial meningitis compared with viral meningitis and with the control group. Similarly, cerebrospinal fluid interleukin-6 levels were found to be significantly higher in children with acute bacterial meningitis compared with viral meningitis. However, no significant difference was determined between groups in respect to the cerebrospinal fluid interleukin-8 level. CONCLUSION: Serum procalcitonin and cerebrospinal fluid tumor necrosis factor alpha levels can be used in the early diagnosis of bacterial meningitis. Similarly, they may be useful adjuncts in differential diagnosis of bacterial and viral meningitis

Dynamic Control of Photoresponse in ZnO-Based Thin-Film Transistors in the Visible Spectrum

Cataloged from PDF version of article.We present ZnO-channel thin-film transistors with actively tunable photocurrent in the visible spectrum, although ZnO band edge is in the ultraviolet. ZnO channel is deposited by atomic layer deposition technique at a low temperature (80 C), which is known to introduce deep level traps within the forbidden band of ZnO. The gate bias dynamically modifies the occupancy probability of these trap states by controlling the depletion region in the ZnO channel. Unoccupied trap states enable the absorption of the photons with lower energies than the bandgap of ZnO. Photoresponse to visible light is controlled by the applied voltage bias at the gate terminal

Proinflammatory Cytokines and Leptin Are Increased in Serum of Prepubertal Obese Children

It has not yet been shown in prepubertal children how cytokines, leptin, and body mass, as well as parameters of obesity are interrelated. The aim of this study was to explore the relation between circulating levels of some cytokines with leptin and body mass index. A case control study was carried out in obese children of both sexes. An obese group was carried out with 63 school prepubertal children and a control group comprised the same number of nonobese children paired by age and by sex. Mean serum leptin concentration was significantly higher in the obese children at 19.9 ± 7.4 ng/mL, than the control group (7.9 ± 5.1 ng/mL). Serum IL-1β, IL-6, and TNF-α levels were also significantly higher in the obese group than controls (33.0 ± 8.9, 45.2 ± 11.8, and 9.2 ± 2.3 pg/mL, versus 3.6 ± 1.0, 13.1 ± 3.9, and 3.9 ± 1.0 pg/mL, resp). In controversy, serum IL-2 level was diminished in the obese group as 0.4 ± 0.1 versus 0.9 ± 0.1 U/L. Obesity may be a low-grade systemic inflammatory disease. Obese prepubertal children have elevated serum levels of IL-1β, IL-6, and TNF-α which are known as markers of inflammation

Amyloid-like peptide nanofiber templated titania nanostructures as dye sensitized solar cell anodic materials

Cataloged from PDF version of article.One-dimensional titania nanostructures can serve as a support for light absorbing molecules and result in an improvement in the short circuit current (Jsc) and open circuit voltage (Voc) as a nanostructured and high-surface-area material in dye-sensitized solar cells. Here, self-assembled amyloid-like peptide nanofibers were exploited as an organic template for the growth of one-dimensional titania nanostructures. Nanostructured titania layers were utilized as anodic materials in dye sensitized solar cells (DSSCs). The photovoltaic performance of the DSSC devices was assessed and an enhancement in the overall cell performance compared to unstructured titania was observed. © 2013 The Royal Society of Chemistry

Serum IL-1β, IL-6, IL-8, and TNF-α Levels in Early Diagnosis and Management of Neonatal Sepsis

Aim. To determine serum IL-1β, IL-6, IL-8, and TNF-α levels in neonatal sepsis at the time of diagnosis and after therapy, and to show the meaningful on the follow up. Methods. This prospective study was performed on newborns who were hospitalized for neonatal sepsis and who were classified as culture-proven sepsis (n=12), as culture-negative sepsis (n=21), and as healthy newborns (n=17). Results. At the time of diagnosis, serum IL-1β, IL-6, IL-8, and TNF-α levels of culture-proven sepsis were significantly higher than those of the control groups (P<.05). At the time of diagnosis, IL-1β, IL-6, IL-8, and TNF-α levels of culture-proven sepsis and culture-negative sepsis were significantly higher than levels at the seventh day after antibiotic treatment. Conclusion. Serum IL-1β, IL-6, IL-8, and TNF-α are mediators of inflammation and can be used at the diagnosis and at the evaluation of the therapeutic efficiency in neonatal sepsis

Serum Endothelin-1 and Transforming Growth Factor-β Levels in the Newborns With Respiratory Distress

The purpose of this present study was to evaluate the serum levels of ET-1 and TGF-β in the newborns with respiratory distress. In this study, newborns with respiratory distress hospitalized into the Newborn Intensive Care Unit were included. The highest values of ET-1 and TGF-β were obtained from newborns with diagnosis as meconium aspiration syndrome (5.70 ± 5.87 pg/mL and 3.75 ± 1.94 pg/mL, resp) in the sample obtained in the first six hours after birth, and these are statistically different from control group (P < .05). Also, same results were obtained for newborns with respiratory distress syndrome (3.37 ± 1.59 pg/mL and 2.05 ± 0.98 pg/mL, resp). After oxygen treatment, ET-1 values obtained in the first six hours of life were decreased regularly in the following days (P < .05). In the differentiating diagnosis of the respiratory distress of newborns, the investigation of ET-1 and TGF-β levels is meaningful. The ET-1 levels investigated in the first six hours is more useful in determining the prognosis, and repeating ET-1 levels in the following days is more meaningful to determine clinical response