Superior Blade Research Articles

Effect of uniformly varying width leading-edge slots on the aerodynamic performance of wind turbine blade

According to the Betz limit, the maximum wind power that can be extracted from wind is limited to 59 %. Practically it stands at a 30–40 % level. Therefore, current research targets to increase the aerodynamic performance of wind turbines by introducing uniformly varying width (UVW) leading-edge slots. In present work, a UVW narrow channel is deployed using NACA (National Advisory Committee for Aeronautics) 4412 aerofoil, which starts from the leading-edge region and goes away to the pressure side of the aerofoil after a slight bending. NACA 4412 aerofoil is chosen as it has the highest lift to drag ratio. Six wind turbine blades of different dimensions (Gradually increasing Wi/Wo ratio) are proposed. Six proposed wind turbine blades are designed and analysed using CFD (computational fluid dynamics) with 0° to 16° at a 2° increment. Wind speed is taken at 7 m/s as per Indian conditions. Out of six proposed blade designs, NACA 4412 aerofoil (Wi/Wo = 2) gives 12 % spike lift to drag ration than the uniform slotted one. Again NACA 4412 aerofoil (Wi/Wo = 2) performs at its peak at angle of attack (AOA) 6°. It is observed that interaction of fluid separation zone and slot inlet results in a down grade of the aerodynamic performance of wind turbine blade. A scaled-down (one-fifth) model of the superior blade (made up of wood) and Solid blade have been made for the wind tunnel test and comparison. The computational results were compared from a series of wind tunnel tests.

Enhancement of blade tip cooling with different position on tip cooling slot

One of the leading causes of thermally induced failure in gas turbine blade tip is a tip leakage flow. To protect blade tip efficiently from strong tip leakage flow, slot cooling is adopted in blade tip considering the application of additive manufacturing. For slot cooling scheme in blade tip, slot location ranging from PS slot to SS slot is a crucial role in film cooling effectiveness of blade tip. Therefore, we investigated the effect of the cooling-slot location on film cooling effectiveness and flow characteristics of blade tip with slot cooling considering the application of additive manufacturing. The local film cooling effectiveness on the blade tip floor and upper surface of the rim are obtained using pressure sensitive paint method. The case of coolant discharge from the PS slot was both stable and evenly spread, resulting in an outstanding coolant coverage of the entire tip regions. However, under severe effect of hot main gas flow behavior, the case of the SS slot resulted in an uneven FCE distributions over the entire tip region from the LE to the TE region. Under the studied tip gaps and coolant mass flow rates, the PS slot configuration provided a superior blade tip cooling performance under most operating conditions, but the SS slot configuration provided an outstanding cooling performance on blade tip only at a large amount of coolant mass flow rate compared to PS slot. Thus, the blade tip with a PS slot is recommended as a robust cooling design. However, the blade tip with a SS slot may have a limited application for design and off-design conditions.

A comparison of two techniques for vaginal speculum placement to reduce patient pain.

Vaginal examination with a speculum is uncomfortable and painful, with approximately 35% of women reporting pain [1-3]. The present study was a longitudinal, prospective, comparative study to compare pain experience after vaginal speculum placement with either a horizontal or vertical technique. For the horizontal technique, the inferior blade of the speculum was placed on the posterior wall of the vagina, at a 90° angle with respect to the antero-posterior axis of the vaginal introitus, and slid forward into the interior of the vagina. With regards to the vertical technique, the superior blade was applied in contact with the right vaginal wall and the inferior blade with the left vaginal wall. The speculum was then slid into the vagina (up to two thirds of the total length of the vagina) and rotated to a horizontal position. In each patient, both techniques were evaluated. Pain was graded on a visual analog scale from 0-10, where 0 indicated no pain and 10 indicated "most intense" perceived pain. Comparison between groups was done by Mann-Whitney U test, and differences between frequencies were calculated by Chi-squared test. The protocol was approved by the Local Ethics in Research Committee 36068 and the Research in Health Committee 3606 with the number R-2020-3606-038. All patients signed an informed consent form for participation in this study.

A brief period of sleep deprivation causes spine loss in the dentate gyrus of mice.

Sleep and sleep loss have a profound impact on hippocampal function, leading to memory impairments. Modifications in the strength of synaptic connections directly influences neuronal communication, which is vital for normal brain function, as well as the processing and storage of information. In a recently published study, we found that as little as five hours of sleep deprivation impaired hippocampus-dependent memory consolidation, which was accompanied by a reduction in dendritic spine numbers in hippocampal area CA1. Surprisingly, loss of sleep did not alter the spine density of CA3 neurons. Although sleep deprivation has been reported to affect the function of the dentate gyrus, it is unclear whether a brief period of sleep deprivation impacts spine density in this region. Here, we investigated the impact of a brief period of sleep deprivation on dendritic structure in the dentate gyrus of the dorsal hippocampus. We found that five hours of sleep loss reduces spine density in the dentate gyrus with a prominent effect on branched spines. Interestingly, the inferior blade of the dentate gyrus seems to be more vulnerable in terms of spine loss than the superior blade. This decrease in spine density predominantly in the inferior blade of the dentate gyrus may contribute to the memory deficits observed after sleep loss, as structural reorganization of synaptic networks in this subregion is fundamental for cognitive processes.

Lesions of retrosplenial cortex spare immediate-early gene activity in related limbic regions in the rat.

The retrosplenial cortex forms part of a network of cortical and subcortical structures that have particular importance for spatial learning and navigation in rodents. This study examined how retrosplenial lesions affect activity in this network by visualising the expression of the immediate-early genes c-fos and zif268 after exposure to a novel location. Groups of rats with extensive cytotoxic lesions (areas 29 and 30) and rats with lesions largely confined to area 30 (dysgranular cortex) were compared with their respective control animals for levels of c-fos expression measured by immunohistochemistry. These cortical lesions had very limited effects on distal c-fos activity. Evidence of a restricted reduction in c-fos activity was seen in the septal dentate gyrus (superior blade) but not in other hippocampal and parahippocampal subareas, nor in the anterior cingulate and prelimbic cortices. Related studies examined zif268 activity in those cases with combined area 29 and 30 lesions. The only clear evidence for reduced zif268 activity following retrosplenial cell loss came from the septal CA3 area. The confined impact of retrosplenial tissue loss is notable as, by the same immediate-early gene measures, retrosplenial cortex is itself highly sensitive to damage in related limbic areas, showing a marked c-fos and zif268 hypoactivity across all of its subareas. This asymmetry in covert pathology may help to explain the apparent disparity between the severity of learning deficits after retrosplenial cortex lesions and after lesions in either the hippocampus or the anterior thalamic nuclei.

Rewriting the tip apex distance for the proximal femoral nail anti-rotation

IntroductionThe proximal femur nail anti-rotation (PFNA-II) (Synthes GmbH, Oberdorf, Switzerland) is the most commonly used implant for intramedullary nailing of unstable intertrochanteric fractures in our centre. However, mechanical failure of the bone with respect to the implant is a cause of concern due to its significant morbidity especially in the elderly. To date, factors for fixation failures are not well defined in the literature. This study aims to evaluate the factors that predispose to cut out of the PFNA implant and to provide a guide for surgical fixation. Patients and methodsThis study was a retrospective analysis of 340 patients who underwent PFNA-II insertion from 2011 to 2013 in our centre.Intraoperative image intensifier images were used for calculation of tip apex distance, neck shaft angles, determination of Cleveland zones. Demographic data was collected on patients age and gender. The fractures were classified based on AO-OTA classification (Marsh et al., 2007) [1]. Patients were followed up for a minimum of 4 months and union of the fracture or until a complication occurred. Risk ratio for cut out was also compared with each statistically significant variable to determine the cut-off point. ResultsThe incidence of cut out was 6.7% Tip apex distance, neck shaft angles and female gender were statistically significant for cut out. The study found that tip apex distance beyond 27mm increased the risk of cut out. Neck shaft angles less than 128° also increased the risk of cut out. Posterior and superior blade position in the femoral head and AO 31A3 fractures trended towards significance for cut out but were not statistically significant. ConclusionTo avoid cut out, one should aim for a tip apex distance of not more than 27mm and preserve a neck shaft angle of more than 128°. Risk stratification of the patient allows the surgeon to take greater caution in the post-operative period to detect early cut out.

A multi-objective optimization for HAWT blades design by considering structural strength

The challenge of wind turbine blade design is to balance the conflict between high capacity and heavy system loads introduced by the large scale rotor. To solve this problem, we present a multi-objective optimization method to maximize the Annual energy production (AEP) and minimize the blade mass. The well-known Blade element momentum (BEM) theory is employed to predict the aerodynamic performance and AEP of the blade. The blade is simplified as a thin Bernoulli beam. The cross section is modelled as a combination of composite layer, shear webs and spar caps typically. The strain of every cross section has been considered as a constraint to minimize the spar cap thickness for minimizing the blade mass. An improved genetic algorithm (NSGA-II) is applied to obtain the Pareto front set. Several solutions of the Pareto set are selected to compare with the reference blade (NREL 5MW blade). Performance of the rotors on design condition is simulated by STAR-CCM+ to verify the results of BEM theory. Optimal results show that the present blade, which is fully superior to the reference blade, can be selected from the Pareto set. The optimization design method can provide a superior blade with an increase by 2.48% of AEP and a reduction by 5.52% of the blade mass. It indicates the present optimization method is effective. Results of numerical simulations show that the spanwise flow would be increased obviously in tip region of the reference blade. The reason is that chord length variation in blade tip affects the flow and causes minor stall. The abrupt change of chord distribution in blade tip should be avoided to reduce the spanwise flow in initial blade design.

Status epilepticus alters neurogenesis and decreases the number of GABAergic neurons in the septal dentate gyrus of 9-day-old rats at the early phase of epileptogenesis

The effects of a prolonged seizure, i.e. status epilepticus (SE), on neurogenesis of dentate granule cells (DGCs) in the immature dentate gyrus (DG) and possible changes in the phenotypes of the newborn neurons have remained incompletely characterized. We have now studied neurogenesis of DGCs in 9-day-old (postnatal, P9) rats 1 week after kainate (KA)-induced SE using 5-bromo-2-deoxyuridine (BrdU) immunostaining. The phenotype characterization of the newborn cells was carried out by immunofluorescence double labeling using doublecortin (DCX) and nestin as markers for immature cells, and glial fibrillary acid protein (GFAP) as a marker for glial cells. Newborn GABAergic neurons were further identified with antibodies for parvalbumin, glutamate decarboxylase 67 (GAD67), and the GABAA receptor α1 subunit, and mRNA expression of GABAergic and immature neurons was measured with quantitative real-time PCR (qPCR) in the DG. Our results show that the number of newborn as well as GABAergic neurons was significantly decreased after SE in the superior blade of the septal DG. The majority of the newborn BrdU-stained neurons co-expressed DCX, but neither nestin nor GFAP. In both experimental groups, newborn neurons were frequently localized in close contact, but not co-localized, with the cells positively stained for the GABAergic cell markers. Nestin and calretinin mRNA expression were significantly increased after SE. Our results suggest that SE-induced disruption of DGC neurogenesis and decreased number of GABAergic neurons could modify the connectivity between these cells and disturb the maturation of the GABAergic neurotransmission in the immature DG at the early epileptogenic phase.

Spatiotemporal distribution of gp130 cytokines and their receptors after status epilepticus: comparison with neuronal degeneration and microglial activation

Although numerous studies have demonstrated the neurotrophic capacity of gp130 cytokines, it remains unclear whether endogenously expressed cytokines actually function in a direct neuromodulatory manner. Therefore, using the lithium–pilocarpine status epilepticus model, we performed a detailed in situ hybridization time-course study of five gp130 cytokines (interleukin [IL]-6, leukemia inhibitory factor [LIF], IL-11, oncostatin-m [OSM], and ciliary neurotrophic factor), gp130, and the receptors of the cytokines we found to be induced (IL-6 receptor [IL-6R], LIF receptor [LIF-R], and IL-11 receptor [IL-11R]). Additionally, to further understand the regulation of these cytokines, we compared their expression with the pattern of neuronal degeneration and microglial activation. Under control conditions, all cytokines, except LIF, exhibited faint to moderate expression in hippocampal principal layers. After seizure, IL-6, LIF, and IL-11 exhibited a rapid, robust, and transient upregulation in non-principal cells. LIF also exhibited a remarkably early and transient induction in the granule cell layer of the dentate gyrus. OSM exhibited only a mild and inconsistent induction. All receptors examined were strongly expressed only in hippocampal principal layers under control conditions. A mild and late induction of the IL-6R, LIF-R, and IL-11R occurred after seizure with a scattered distribution. A progressive and chronic induction of gp130 was observed in cells that appeared to be associated with blood vessels. Degeneration of hilar interneurons and CA1 pyramidal cells was early and progressive. Granule neurons of the dentate gyrus, however, exhibited a delayed and precipitous pattern of degeneration, specifically in the lateral portion of the superior blade. Microglial activation was maximal 24–48 h post-seizure. We speculate that gp130 cytokines play a paracrine, neuromodulatory role in the hippocampus since both before and after seizure, principal cells appear to be the major cell type expressing the receptors for these cytokines. Furthermore, we suggest that activity-dependent mechanisms may be involved in the regulation of cytokines expressed early, and that relatively late occurring cytokine expression may be elicited by injury-related stimuli.

Persistently High Corticosterone Levels but Not Normal Circadian Fluctuations of the Hormone Affect Cell Proliferation in the Adult Rat Dentate Gyrus

The dentate gyrus is one of the few brain structures where new neurons are added throughout adulthood in several mammalian species, including humans. Production of new neurons can be regulated by factors which influence cell proliferation or newborn cell survival. Supplementation or deprivation of glucocorticoids, adrenal hormones involved in the response to stress, affect cell proliferation, leading to a decrease or an increase, respectively, in the number of newborn cells. Glucocorticoid secretion under physiological conditions follows a circadian pattern. We thus investigated a possible relationship between cell proliferation and circadian oscillations of corticosterone secretion in the adult rat dentate gyrus. Corticosterone is the species-specific glucocorticoid hormone of the rat. 5-Bromo-2′-deoxyuridine was used to evaluate cell proliferation at 4 different time points in the light-dark cycle. No correlation was found between corticosterone circadian oscillations and cell proliferation in the adult dentate gyrus. In contrast, constantly high corticosterone levels, obtained by implanting corticosterone pellets, decreased cell proliferation in particular zones of the dentate gyrus, i.e. the hilus and the superior blade of the granule cell layer. These findings show that a short, physiologically occurring exposure to high corticosterone levels does not influence cell proliferation, whereas a lengthy exposure to this hormone does induce anatomically localized proliferative changes.

5-HT1A receptor agonist reverses adrenalectomy-induced loss of granule neuronal morphology in the rat dentate gyrus.

Adrenal steroids are important for maintaining neuronal maturation in the adult rats. Two weeks after bilateral adrenalectomy (ADX), hippocampal MAP-2 (microtubule associated protein-2) and calbindin immunoreactivity (IR) decreased in the molecular layer of the superior blade of the dentate gyrus. The molecular and granular cell layer at the lateral tip of the superior blade decreased in width by 32% and 50%, respectively. The granule neurons showed reduced staining with Nissl and an anti-calbindin antibody. These changes suggested a loss of the mature neuronal morphology. In this same localized regions, two glial proteins, glial fibrillary acidic protein (GFAP) and S-100 beta showed dramatically reduced immunoreactivity. These effects induced by ADX were reduced within 72 hrs by ipsapirone (1 mg/kg), a 5HT1A receptor agonist. Loss of adult neuronal morphology by ADX, and reversal by the 5HT1A agonist, may be evidence of the trophic importance of the 5HT1A receptor in granule neurons of hippocampus.

Dentate granule cell layer collagen explant cultures: spontaneous axonal growth and induction by brain-derived neurotrophic factor or basic fibroblast growth factor.

The molecular mechanisms that underlie dentate granule cell axon (i.e., mossy fiber) growth during development and following seizure-induced hippocampal injury remain unknown. Part of this process may involve specific factors that support dentate granule cells during differentiation, and molecular cues that allow the appropriate growth of mossy fiber axons toward their targets. To study this process, we developed an in vitro assay system to measure the activity of putative trophic, chemoattractant and chemorepulsive factors. Two-hundred-micrometer-thick transverse hippocampal sections were prepared from neonatal rats and microdissected to isolate the middle one-third of the superior blade of the dentate granule cell layer. These were embedded in a three-dimensional collagen matrix either alone or with microdissected regions of the CA2 pyramidal cell layer. Cultures were maintained in a defined medium and grown for two to three days in a standard culture environment. Results showed that numerous processes grew primarily from the hilar side of explants into the collagen matrix, often in excess of 500 microns in length. These were determined to be axons based on: (i) morphological criteria including size and presence of growth cones, (ii) synaptophysin and growth-associated protein-43 immunoreactivity, (iii) lack of glial fibrillary acidic protein immunoreactivity and (iv) contiguity of biocytin-filled processes with neuronal soma within the explant. Treatment of cultures with brain-derived neurotrophic factor caused a significant increase in axon number and length, and this effect was partially reversed by the addition of a trkB-immunoglobulin fusion protein that blocks the activity of brain-derived neurotrophic factor and neurotrophin-4/5. Basic fibroblast growth factor also caused a marked increase in axon number and length, and caused a migration of neuron-like cells out of the explant into the collagen. These results show that cultured dentate granule cell layer explants are capable of growing mossy fibers into a neutral collagen matrix, and the growth of axons can be modified by the addition of exogenous growth factors. Furthermore, since target tissue and point sources of purified factors can easily be co-cultured with the explants, this new system provides a direct means for testing the molecular cues that influence mossy fiber growth.

Developmental changes in membrane properties and postsynaptic currents of granule cells in rat dentate gyrus.

1. Whole cell patch-clamp recordings were used to study dentate gyrus granule cells in hippocampal slices from juvenile rats (postnatal days 8-32). Membrane properties were measured with the use of current-clamp recordings and were correlated with the morphology of a subgroup of neurons filled with biocytin. The components of the postsynaptic currents (PSCs) induced by medial perforant path stimulation were characterized with the use of specific receptor antagonists in voltage-clamp recordings. 2. Granule cells located in the middle third of the superior blade of stratum granulosum from the rostral third of hippocampus were divided into three groups according to their input resistance (IR). Neurons with low IR (206 +/- 182 M omega, mean +/- SD) had hyperpolarized resting membrane potentials (-82 +/- 7 mV) and high-amplitude action potentials (108 +/- 23 mV). Neurons were high IR (1,259 +/- 204 M omega) had more depolarized resting membrane potentials (-54 +/- 6 mV) and lower-amplitude action potentials (71 +/- 10 mV). Neurons with intermediate IR (619 +/- 166 M omega) also had intermediate resting membrane potentials (-63 +/- 7 mV) and action potential amplitudes (86 +/- 14 mV). Low-IR neurons became increasingly prevalent with advancing postnatal age, but neurons from each group could be found throughout the entire period under study. 3. Morphological studies of low-IR neurons revealed an extensive dendritic arborization that traversed the entire molecular layer and was characteristic of mature granule cells. High-IR cells had smaller somata and short, simple dendritic arborization that incompletely penetrated the molecular layer and were classified as immature. Intermediate-IR cells had morphological features of intermediate maturity. 4. The initial phase of the PSC evoked at -80 mV was a fast inward current that was comparable with respect to latency to peak, latency to onset, and 10-90% rise time in neurons of all maturities held at -80 mV. This current was 6-cyano-7-nitroquinoxaline-2,3-dione sensitive. 5. The decay phases of PSCs at -80 mV varied with neuronal maturity. Mature neurons had monoexponential decays (tau = 8.9 +/- 3.6). Intermediate and immature neurons had prominent later inward currents that resulted in slower decays. In the case of the immature neurons, the inward current during the decay phase could be separated from the initial fast inward peak. The later inward currents in intermediate and immature neurons were bicuculline sensitive. 6. With the use of uniform ionic conditions of the extracellular and patch solutions, current-voltage relations and reversal potentials for pharmacologically isolated alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA), N-methyl-D-aspartate (NMDA), and gamma-aminobutyric acid-A (GABAA) currents were comparable across all cell maturities. Calculated ratios for peak GABAA/NMDA/AMPA currents decreased significantly with maturation as follows: 9.4 +/- 2.9/1.4 +/- 0.5/1.0 for immature cells, 7.2 +/- 2.5/1.5 +/- 0.7O/1.0 for intermediate cells, and 2.0 +/- 1.2/0.9 +/- 0.4/1.0 for mature cells. 7. GABA current was mediated both by polysynaptic activation of interneurons and by direct activation of interneurons with monosynaptic input onto granule cells. The proportional contributions of mono- and polysynaptic GABA to total GABA were comparable across all cell maturities; latency to peak GABA current decreased with increasing cell maturity for both mono- and polysynaptic components. 8. We conclude that PSCs evoked in granule cells by medial perforant path activation in neurons of all maturities consist of both glutamatergic and GABAergic components. PSCS are dominated by GABAergic neurotransmission in immature granule cells, and the contribution of glutamatergic neurotransmission increases with neuronal maturation. The greater ratio of peak GABAA to glutamate currents and the longer time interval between their respective peaks combine to produce a distinctive PSC shape