bluuebunny/crossref_metadata_2025_split huggingface dataset:
INFLUENCE OF RUMINAL AND PLASMA OSMOTIC PRESSURE ON SALIVARY SECRETION IN SHEEP
Authors: Warner A. C. I. , Stacy B. D. 
Published: December 2014

The osmotic pressure of the rumen contents and also of the blood was altered by intraruminal administration of water or hypertonic solutions. It was found that alterations in osmotic pressure were accompanied by inverse changes in the flow rate of mixed saliva. Intravenous infusion of hypertonic solutions, causing elevation of the osmotic pressure of the blood without affecting that of the rumen, also caused a reduction of salivary secretion rate. The flow rates of both parotid and residual saliva were affected.When strongly hypertonic solutions of sodium or potassium salts were infused into the rumen, or sodium salts or urea were infused into the blood, the concentration of those substances increased in the saliva. Other treatments had little effect on salivary composition.
A STUDY OF CHEMICALLY INDUCED ACUTE INFLAMMATION IN THE SKIN OF THE RAT
Authors: Kiernan J. A. 
Published: December 2014

Oedema due to application of benzene to the skin was reduced following prior sensory denervation and in animals systemically pre‐treated with capsaicine (which is known to confer resistance to chemical irritants) or compound 48/80 (which depletes the body of mast cells). Increased degranulation of mast cells in the benzene‐treated skin was unaffected by denervation but did not occur after treatment with capsaicine.Antidromic stimulation of a cutaneous nerve caused oedema and degranulation of mast cells, both of which were less severe than the corresponding effects of topically applied benzene. These effects were completely prevented by prior treatment with capsaicine and the oedema was less severe in 48/80‐treated rats. Hence, the presence of mast cells was necessary for full development of the effects of antidromic stimulation.These observations indicate that axon reflexes in sensory fibres contribute to, but are not entirely responsible for, the development of oedema in chemically irritated skin. The prophylactic action of capsaicine may be due to the prevention of degranulation of mast cells rather than to a direct effect on cutaneous nerve endings. These conclusions are embodied in an hupothesis purporting to explain the involvement of axon reflexes, mast cells and various humoral mediators in chemically induced acute inflammation.
Sympathetic and β‐Adrenergic Stimulation of Parotid Salivary Secretion in Sheep
Authors: Patterson J. , Titchen D. A. 
Published: December 2014

The effects of sympathetic and β‐adrenergic stimulation (with isoprenaline) on the secretion of parotid saliva were examined in anaesthetized and totally pithed preparations of sheep. This was studied against a background of spontaneous secretion or of secretion augmented by pilocarpine. In addition to the previously established α‐ adrenergic sympathetic motor effect causing mechanical expulsion of saliva, a β‐ adrenergic secretory response has now been identified. Characteristically, the secretory effect was obtained from electrical stimulation of the cervical sympathetic nerve trunk when lower frequencies or shorter pulse durations were used. This secretory effect and similar responses to isoprenaline were blocked by propranolol.Two phenomena confirmed that the β‐adrenergic responses to sympathetic stimulation were secretory: namely there were nett increases in the amount of fluid formed (by as much as 128% or as great as 93·9 mg saliva.gm gland‐1.min‐1), and they were accompanied by increases in the protein content of the parotid saliva (up to 8–9 fold). The amounts of protein rose from resting levels of 10–170 µg.ml‐1 (expressed as equivalents of bovine serum albumin) to as high as 840µg.ml‐1 in response to single i.v. injections of 2 µg.kg‐1 of isoprenaline, and to 1240µg.ml‐1 with cervical sympathetic nerve stimulation.It is concluded that there is a sympathetic secretory innervation in parotid salivary glands of sheep that is mediated by β‐adrenergic mechanisms.
Endometrial Blood Flow in Anaesthetized Sheep as Measured with Krypton‐85 Clearance and Microsphere Techniques
Authors: Fraser I. S. , Brown B. W. , Mattner P. E. 
Published: December 2014

Uterine blood flow rates were obtained with a Krypton (85Kr) clearance technique and with radio‐active microspheres in six anaesthetized, non‐pregnant ewes (a total of ten comparisons). 85Kr was administered, via a catheter, into the abdominal aorta and β‐emissions were detected with a catheter‐type semi‐conductor detector probe situated in the lumen of a uterine horn.In seven instances, the 85Kr clearance curve had only one component while in the remaining three instances the curves could be resolved into two components. The flow rates derived from the single component curves and the mean flow rates calculated from the curves with two components were of the same order as, and highly correlated with, estimates of capillary blood flow obtained with microspheres for either the caruncles, the inter‐caruncular endometrium or the total endometrium (r=0·832, r=0·822 and r=0·841, respectively, P<0·005). There was no correlation between the flow rates obtained with the 85Kr technique and estimates of myometrial capillary blood flow obtained with microspheres.
THE QUEST FOR THE INHIBITORY NEUROTRANSMITTER IN BOVINE TRACHEAL SMOOTH MUSCLE
Authors: Cameron A. R. , Johnston C. F. , Kirkpatrick C. T. , Kirkpatrick Melanie C. A. 
Published: December 2014

The effect of inhibitory nerve stimulation on the mechanical, membrane potential and membrane conductance responses of isolated bovine tracheal smooth muscle has been studied. Membrane responses were measured in a sucrose‐gap apparatus. In order to record inhibitory responses, it was necessary to increase tone in the preparation by applying a drug such as histamine. When tone was raised, repetitive field stimulation of intrinsic nerves caused depolarization and contraction, followed by relaxation and a suppression of histamine‐induced slow waves. Hyperpolarization of the membrane was only seen following prolonged nerve stimulation, and there was no change in membrane conductance. The inhibitory effect of nerve stimulation was abolished by tetrodotoxin, but was not abolished by atropine, indomethacin, propranolol, naloxone or the purinergic blockers quinidine and theophylline. It was not satisfactorily mimicked by catecholamines, by γ‐amino‐n‐butyric acid (GABA) or by purines.Nerves with catecholamine fluorescence could not be found in the tracheal muscle layer. Neither adrenergic nor purinergic types of nerve terminal could be found in the tracheal muscle layer during ultrastructural examination of over one thousand nerve profiles. Vasoactive intestinal peptide (VIP) caused relaxation of the histamine‐contracted tracheal muscle, suppressed the slow wave and caused slight hyperpolarization at higher concentrations, without affecting the membrane conductance. VIP was found in samples of tracheal muscle at a mean concentration of 1·95 ng/g. When the effluent solution flowing past isolated tracheal muscle strips was assayed for VIP, samples collected during inhibitory nerve stimulation had much higher concentrations of the peptide than samples collected before stimulation, after stimulation, or during stimulation in the presence of tetrodotoxin (10–6 mol/l). The VIP content of the effluent during control periods was 73·8 pg/ml, and during stimulation was 167·5 pg/ml. It is suggested that VIP might be the non‐adrenergic inhibitory neurotransmitter in bovine tracheal smooth muscle.
THYROID HORMONE METABOLISM AFTER ACCLIMATIZATION TO A WARM OR COLD TEMPERATURE UNDER CONDITIONS OF HIGH OR LOW ENERGY INTAKE
Authors: Macari M. , Dauncey M. J. , Ingram D. L. , Ramsden D. B. 
Published: December 2014

The separate effects of ambient temperature and energy intake on the metabolism of thyroid hormones in the young pig have been investigated. Piglets were kept singly from 4 weeks of age at 10 or 35 °C on a high (H), or low (L) energy intake, such that H = 2L. At the tenth week of age blood samples were taken 16–21 h after the last meal for the determination of plasma concentrations of thyroxine (T4) and 3,5,3‐triiodothyronine (T3). At the end of the tenth week of age the fractional disappearance rate (K) of T4 was determined and finally the K value for T3 was estimated.Plasma concentrations of T4 and T3 were greater in animals on a high intake than in those on a low intake, (P 〈 0·02), but the temperature at which the animals lived had no significant effect. The values of K for T4 and T3 were greater at 10 than at 35 °C (P 〈 0·010 and P 〈 0·05), and energy intake had no significant effect. Calculations of the catabolic rates in nmol/kg.h revealed that for T4 the rate was greater at 10 than at 35 °C (P 〈 0·001) and on a high than on a low intake (P 〈 0·01). Similar differences were found between the mean values of T3 with respect to both temperature and energy intake, but the variance was large and they did not reach statistical significance.It is concluded that the metabolism of thyroid hormones is influenced independently by both ambient temperature and energy intake.
A HIGH‐CONDUCTANCE CALCIUM‐DEPENDENT CHLORIDE CHANNEL IN ASCARIS SUUM MUSCLE
Authors: Thorn P. , Martin R. J. 
Published: December 2014

Quarterly Journal of Experimental Physiology 72 (1987)Page 44, eqn. (10), should read:Pr = n! / r!(n‐r)! Pr(1‐P)n‐r
Inflammation and oxidative stress during intermittent hypoxia: the impact on chemoreception
Authors: Iturriaga Rodrigo , Moya Esteban A. , Del Rio Rodrigo 
Published: December 2014

New Findings

What is the topic of this review?
This article describes the contribution of oxidative stress and pro‐inflammatory cytokines to the enhanced carotid body chemosensory responsiveness to the hypoxia and systemic hypertension induced by chronic intermittent hypoxia.

What advances does it highlight?
Chronic intermittent hypoxia enhances the carotid body chemosensory discharge during normoxia and hypoxia, leading to sympathetic overactivity and hypertension. New evidence suggests that chronic intermittent hypoxia increases pro‐inflammatory cytokines. Here, we discuss the role of inflammation in the alterations of the carotid chemoreceptor function as well as the cardiorespiratory alterations following chronic intermittent hypoxia.

Chronic intermittent hypoxia (CIH), the main characteristic of obstructive sleep apnoea, enhances carotid body (CB) chemosensory discharges during normoxia and hypoxia and elicits hypertension. These alterations are attributed to oxidative stress, because antioxidants prevent the enhanced CB chemosensory discharges and the hypertension. In this report, we discuss new evidence supporting the suggestion that oxidative stress‐induced upregulation of pro‐inflammatory cytokines (i.e. tumour necrosis factor‐α and interleukin‐1β) in the CB is involved in the chemosensory potentiation and the hypertension following CIH. Anti‐inflammatory treatment with ibuprofen prevents the increased tumour necrosis factor‐α and interleukin‐1β levels in the CB and the hypertension, but does not reduce the enhanced chemosensory hypoxic response and the local oxidative stress in the CB. In contrast, antioxidant treatment with ascorbic acid prevents the increase in cytokine concentrations and CB oxidative stress, the chemosensory potentiation and the hypertension. Thus, the enhanced CB chemosensory responses to hypoxia depend critically on the oxidative stress, but not on the increased tumour necrosis factor‐α and interleukin‐1β in the CB. We discuss a possible role for pro‐inflammatory cytokines in development of the hypertension produced by CIH, acting on cardiorespiratory centres located in the CNS.
Cooled Cooling Air Systems for Turbine Thermal Management
Authors: Bruening Greg B. , Chang Won S. 
Published: December 2014

This paper evaluates the feasibility and potential impact on overall engine performance when utilizing the heat sink sources available in a gas turbine engine for improved turbine thermal management. A study was conducted to assess the application of a heat exchanger to cool the compressor bleed air normally used air for cooling turbine machinery. The design tradeoffs of this cooled cooling air approach as we’ll as the methodology used to make the performance assessment will be addressed.
The results of this study show that the use of a cooled cooling air (CCA) system can make a positive impact on overall engine performance. Minimizing the complexity and weight of the CCA system, while utilizing advanced, high temperature materials currently under development provide the best overall solution in terms of design risk and engine performance.
Numerical and Experimental Investigations on the Flow in a 4-Stage Turbine With Special Focus on the Development of a Radial Temperature Streak
Authors: Bonn Dieter , Funke Harald , Gier Jochen 
Published: December 2014

In the development of modern gas turbines the increase of the turbine inlet temperature is restricted by the need to cool the first stages of the turbine. In addition the flow leaving the combustor is thermally inhomogeneous. Since the blade cooling has to be designed for the actual local hot gas temperatures, it is important to know how these temperature inhomogeneities develop and attenuate inside the multistage flow passage.
In this investigation the flow inside a 4-stage turbine, which is set up in a test rig at the Institute of Steam and Gas Turbines, Aachen University of Technology, is calculated with a state-of-the-art fully three-dimensional Navier-Stokes solver based on an accurate finite volume scheme. The stator and rotor rows are coupled via mixing planes. The turbine is a scaled down original turbine with realistic axial gaps.
The homogeneous reference case is qualified by comparison to recent experimental data gathered at the test rig. Therefore, the flow is extensively measured at several locations. In a second step a radial temperature streak is set at the inlet for the same point of operation. The results show the development of the temperature streak through the four stages. With this information the underlying mixing processes are described and analysed. It is found that the hot streak segregation effect is present in all four stages.
The Origin of Turbulent Spots
Authors: Johnson Mark W. , Dris Antonis 
Published: December 2014

It has been suggested that a turbulent spot is formed when a transient separation occurs in the laminar boundary layer and this criterion has been successfully used by Johnson and Ercan [1996,1997] to predict bypass transition for boundary layers subjected to a wide range of freestream turbulence levels and streamwise pressure gradients. In the current paper experimental results are presented which support the premise that the formation of turbulent spots is associated with transient separation. Near wall hot wire signals in laminar and transitional boundary layers are analysed statistically to produce probability distributions for signal level and trough frequency. In the laminar period the signal level is normally distributed, but during the inter-turbulent periods in the transitional boundary layer the distribution is truncated at the tower end, i.e. the lowest velocity periods in the signal disappear, suggesting that these are replaced during transition by the turbulent periods. The number of these events (troughs) also correlates with the number of turbulent spots during early transition.
A linear perturbation theory is also used in the paper to compute the streamlines through a turbulent spot and its associated calmed region. The results indicate that a hairpin vortex dominates the flow and entrains a low momentum fluid stream from upstream with a high momentum stream from downstream and then ejects the combined stream into the turbulent spot. The hairpin can only exist if a local separation occurs beneath its nose and the current results suggest that this separation is induced when the instantaneous velocity in the near wall signal drops below 50% of the mean.
Effect of Internal Coolant Crossflow Orientation on the Discharge Coefficient of Shaped Film Cooling Holes
Authors: Gritsch Michael , Saumweber Christian , Schulz Achmed , Wittig Sigmar , Sharp Edwin 
Published: December 2014

Discharge coefficients of three film-cooling hole geometries are presented over a wide range of engine like conditions. The hole geometries comprise a cylindrical hole and two holes with a diffuser shaped exit portion (a fanshaped and a laidback fanshaped hole). For all three hole geometries the hole axis was inclined 30° with respect to the direction of the external (hot gas) flow. The flow conditions considered were the hot gas crossflow Mach number (up to 0.6), the coolant crossflow Mach number (up to 0.6) and the pressure ratio across the hole (up to 2).
The effect of internal crossflow approach direction, perpendicular or parallel to the main flow direction, is particularly addressed in the present study. Comparison is made of the results for a parallel and perpendicular orientation, showing that the coolant crossflow orientation has a strong impact on the discharge behavior of the different hole geometries. The discharge coefficients were found to strongly depend on both hole geometry and crossflow conditions.
Furthermore, the effects of internal and external crossflow on the discharge coefficients were described by means of correlations used to derive a predicting scheme for discharge coefficients. A comparison between predictions and measurements reveals the capability of the method proposed.
An Experimental Investigation of the Flow in a 1½ Stage Axial Turbine With Regard to a High Level of Cooling-Air Injection
Authors: Reinmöller U. , Gallus H. E. 
Published: December 2014

Experimental investigations of flow mixing due to film cooling of turbine blades have been performed. In a 1½-stage axial air turbine cooling gas (cool nitrogen down to −130 °C) was blown directly onto the leading edge of the first stator by special gas injector devices. In order to provide a database for the verification of numerical codes and to give an impression of the mixing process the gas has been injected at different radial positions. Furthermore the cooling massflow and cooling temperature were varied. The measuring data were obtained using pneumatic 5-hole probes with temperature sensors.
The presented experimental data were simultaneous acquired in the planes behind both stators and the rotor. The results are compared and, discussed with reference measurements without cooling gas injection. It is shown that the effect of cooling gas injection is apparent in the wake of the first stator where it causes a small decrease in the pressure distribution as a result of increased flow mixing. Behind the first stator differences in the circumferentially averaged pitchwise flow angle due to the injected gas were not measured. Furthermore, temperature measurements clearly show the effect of the cooling gas injection in all planes. Even behind the second stator the different magnitudes of the temperature distribution are caused by the various injection of cooling gas.
Performance of a Turbine Airfoil With Multiple Film Cooling Stations: Part II — Aerodynamic Losses
Authors: Drost U. , Bölcs A. 
Published: December 2014

In the present study the aerodynamic performance of a turbine NGV airfoil was investigated, cooled from several showerhead, pressure and suction side stations. Film cooling heat transfer and effectiveness on this airfoil was examined in part I of this paper. Tests were conducted in a linear cascade at an exit Reynolds number of 1.45e6 and an exit Mach number 0.8. Density ratio effects were studied with air and CO2 injection, matching the densities by correctly adjusting the coolant temperature.
In terms of a primary loss coefficient, neglecting the coolant kinetic energy, coolant injection increased the losses by 20–30% compared to solid blade losses, but depended only weakly on the coolant mass flow rate. A slight loss increase for increasing injection up to 2% coolant mass flow was noted, followed by a weak decrease for further augmented coolant mass flow rates. The primary losses appeared to be independent of the coolant medium and temperature.
Thermodynamic loss coefficients including the loss of coolant kinetic energy, monotonically increased with coolant mass flow rates. To check the validity of CO2 injection for the simulation of high density ratios, the latter has been matched using strongly cooled air and heated CO2. The thermodynamic losses did not match at constant density ratio, but at constant coolant Mach number, when compared at constant coolant mass flow rates. Reporting the losses to the total pressure ratio (momentum flux ratio) yielded excellent scaling emphasizing the usefulness of the momentum flux ratio for film cooling loss scaling.
The Role of Carbon Monoxide in NO2 Plume Formation
Authors: Feitelberg Alan S. , Correa Sanjay M. 
Published: December 2014

Through a series of computational studies, carbon monoxide has been identified as an important promoter of NO oxidation to NO2 in combustion turbine exhaust gas at intermediate temperatures (450 to 750°C). NO2 formation is accompanied by enhanced CO burnout at these temperatures. Perfectly stirred reactor and plug flow reactor calculations indicate that concentrations of CO as low as 50 ppmv in exhaust gas containing 25 ppmv NO can result in the conversion of 50% of the NO to NO2 in less than 1 second. NO2 concentrations as low as 15 ppmv can result in visible, yellow-brown plumes from large diameter exhaust stacks. If NO2 plumes are to be prevented, then designers of gas turbines and heat recovery steam generators need to be aware of the relationships between time, temperature, and composition which cause NO2 to form in exhaust gas.
Reaction path analysis indicates that the mutually promoted oxidation of CO and NO occurs through a self-propagating, three-step chain reaction mechanism. CO is oxidized by OH, (R2)CO+OH→CO2+Hwhile NO is oxidized by HO2:(R23)NO+HO2→NO2+OHIn a narrow temperature range, the H-atom produced by R2 can react with O2 in a three body reaction to yield the hydroperoxy radical needed in R23:(R9)H+O2+M→HO2+Mwhere M is any third body. The observed net reaction isCO+O2+NO→CO2+NO2which occurs stoichiometrically at temperatures below about 550°C. As the temperature increases, additional reaction pathways become available for H, HO2, and OH which remove these radicals from the chain and eventually completely decouple the oxidation of CO from NO.
An abbreviated set of elementary chemical reactions, including 15 species and 33 reactions, has been developed to model CO-enhanced oxidation of NO to NO2. This reaction set was derived from a larger reaction set with more than 50 species and 230 elementary chemical reactions, and was validated by comparison of PSR and PFR calculations using the two sets.