Unsteady Thick Airfoil Aerodynamics: Experiments, Computation, and Theory

An experimental, computational and theoretical investigation was carried out to study the aerodynamic loads acting on a relatively thick NACA 0018 airfoil when subjected to pitching and surging, individually and synchronously. Both pre-stall and post-stall angles of attack were considered. Experiments were carried out in a dedicated unsteady wind tunnel, with large surge amplitudes, and airfoil loads were estimated by means of unsteady surface mounted pressure measurements. Theoretical predictions were based on Theodorsen's and Isaacs' results as well as on the relatively recent generalizations of van der Wall. Both two- and three-dimensional computations were performed on structured grids employing unsteady Reynolds-averaged Navier-Stokes (URANS). For pure surging at pre-stall angles of attack, the correspondence between experiments and theory was satisfactory; this served as a validation of Isaacs theory. Discrepancies were traced to dynamic trailing-edge separation, even at low angles of attack. Excellent correspondence was found between experiments and theory for airfoil pitching as well as combined pitching and surging; the latter appears to be the first clear validation of van der Wall's theoretical results. Although qualitatively similar to experiment at low angles of attack, two-dimensional URANS computations yielded notable errors in the unsteady load effects of pitching, surging and their synchronous combination. The main reason is believed to be that the URANS equations do not resolve wake vorticity (explicitly modeled in the theory) or the resulting rolled-up un- steady flow structures because high values of eddy viscosity tend to \smear" the wake. At post-stall angles, three-dimensional computations illustrated the importance of modeling the tunnel side walls

Freezing Strip Loin and Top Round Steaks Improves Warner-Bratzler Shear Force

Postmortem aging of steaks is a common practice used to improve tenderness of beef steaks. The impact of proteolysis and improvement in tenderness due to aging varies among muscles. When designing research protocols, samples for Warner-Bratzler shear force (WBSF) are often frozen for later analysis because of convenience and time limitations. Freezing stops postmortem aging and allows for storage until meat can be cooked for WBSF and/or sensory analysis. However freezing meat may cause damage to cell membranes resulting in lower Warner-Bratzler shear force (improved mechanical tenderness), lower water holding capacity, and greater moisture loss during cooking. Several researchers have indicated that freezing strip loin (Longissimus muscle) steaks may lower Warner-Bratzler shear force (improve tenderness) compared with those not previously frozen and sheared fresh. However, these results have been inconclusive for steaks from other muscles. Therefore, the objective of this study was to determine the effects of postmortem aging time and freezing on Warner-Bratzler shear force of six muscles from the beef hindquarter

The Use of Bioelectrical Impedance to Assess Shelf-Life of Beef Longissimus Lumborum Steaks

Objective: The objective of this study was to evaluate the efficacy of using surface and internal bioelectrical impedance to assess beef longissimus lumborum shelf-life during 15 days of simulated retail display. Study Description: Beef strip loins, obtained from three commercial processors (postmortem age = 27, 34, or 37 days), were fabricated into 12 1-inch thick steaks. Steaks were subdivided into six consecutively cut pairs, packaged on Styrofoam trays, overwrapped with polyvinyl chloride film, and displayed under fluorescent lighting at 32–40°F in coffin-style retail cases for 15 days. Microbiological analysis, pH, bioelectrical impedance analysis, objective color assessment, proximate composition, and lipid oxidation were measured. Surface and internal bioelectrical impedance assessment were compared. The Bottom Line: Internal bioelectrical impedance has potential for use to assess shelf-life of retail steaks and it was more precise than surface bioelectrical impedance; however, internal bioelectrical impedance may translocate bacteria into the muscle. Protein degradation and water holding capacity should be evaluated to better understand bioelectrical impedance changes over time

Beef Longissimus Lumborum Steak pH Affects External Bioelectrical Impedance Assessment

Objective: To use external bioelectrical impedance analysis to assess postmortem chemical changes in normal- and high-pH beef longissimus lumborum steaks during simulated retail display. Study Description: Beef strip loins (n = 20; postmortem age = 14 d) obtained from a commercial processor were sorted into two treatments, normal-pH (5.61–5.64; n = 11) and high-pH (6.2–7.0; n = 9). Loins were fabricated into five 1-inch thick steaks (n = 100), and randomly assigned to one of five display days: 1, 3, 5, 7, and 9. External bioelectrical impedance values, oxygen consumption, metmyoglobin reducing ability, protein degradation, water holding capacity, and pH were assessed on each storage day. The Bottom Line: External bioelectrical impedance is a method that could be used to separate normal- and high-pH strip loins with potential for rapid, in-plant use to identify dark-cutting beef

Tuning ZnO Sensors Reactivity toward Volatile Organic Compounds via Ag Doping and Nanoparticle Functionalization

Nanomaterials for highly selective and sensitive sensors toward specific gas molecules of volatile organic compounds (VOCs) are most important in developing new-generation of detector devices, for example, for biomarkers of diseases as well as for continuous air quality monitoring. Here, we present an innovative preparation approach for engineering sensors, which allow for full control of the dopant concentrations and the nanoparticles functionalization of columnar material surfaces. The main outcome of this powerful design concept lies in fine-tuning the reactivity of the sensor surfaces toward the VOCs of interest. First, nanocolumnar and well-distributed Ag-doped zinc oxide (ZnO:Ag) thin films are synthesized from chemical solution, and, at a second stage, noble nanoparticles of the required size are deposited using a gas aggregation source, ensuring that no percolating paths are formed between them. Typical samples that were investigated are Ag-doped and Ag nanoparticle-functionalized ZnO:Ag nanocolumnar films. The highest responses to VOCs, in particular to (CH3)2CHOH, were obtained at a low operating temperature (250 °C) for the samples synergistically enhanced with dopants and nanoparticles simultaneously. In addition, the response times, particularly the recovery times, are greatly reduced for the fully modified nanocolumnar thin films for a wide range of operating temperatures. The adsorption of propanol, acetone, methane, and hydrogen at various surface sites of the Ag-doped Ag8/ZnO(0001) surface has been examined with the density functional theory (DFT) calculations to understand the preference for organic compounds and to confirm experimental results. The response of the synergistically enhanced sensors to gas molecules containing certain functional groups is in excellent agreement with density functional theory calculations performed in this work too. This new fabrication strategy can underpin the next generation of advanced materials for gas sensing applications and prevent VOC levels that are hazardous to human health and can cause environmental damages

CD28 between tolerance and autoimmunity: The side effects of animal models [version 1; referees: 2 approved]

Regulation of immune responses is critical for ensuring pathogen clearance and for preventing reaction against self-antigens. Failure or breakdown of immunological tolerance results in autoimmunity. CD28 is an important co-stimulatory receptor expressed on T cells that, upon specific ligand binding, delivers signals essential for full T-cell activation and for the development and homeostasis of suppressive regulatory T cells. Many in vivo mouse models have been used for understanding the role of CD28 in the maintenance of immune homeostasis, thus leading to the development of CD28 signaling modulators that have been approved for the treatment of some autoimmune diseases. Despite all of this progress, a deeper understanding of the differences between the mouse and human receptor is required to allow a safe translation of pre-clinical studies in efficient therapies. In this review, we discuss the role of CD28 in tolerance and autoimmunity and the clinical efficacy of drugs that block or enhance CD28 signaling, by highlighting the success and failure of pre-clinical studies, when translated to humans

Differences in Rumination and Animal Activity Can Be Quantified by Utilizing New Technologies

Objective: Utilizing new technologies such as Allflex eSense Ear Tags to (Allflex Livestock Intelligence, Madison, WI) evaluate the impacts of limit feeding a high-energy diet in the backgrounding phase on daily rumination and activity in growing cattle. Study Description: This project was conducted in conjunction with the performance backgrounding study at the Kansas State University Beef Stocker Unit in 2019. Crossbred heifers (n = 418) were outfitted with an ear tag that measured rumination and activity throughout the day and the 84-day backgrounding study. This data was continuously collected via an onsite antenna, downloaded to a computer, and analyzed in a software program. The Bottom Line: High-energy, limit-fed cattle ruminate less than high roughage, ad libitum cattle by 45 minutes in this study. There were no detected differences in animal activity

Insulin and GH Signaling in Human Skeletal Muscle In Vivo following Exogenous GH Exposure: Impact of an Oral Glucose Load

GH induces acute insulin resistance in skeletal muscle in vivo, which in rodent models has been attributed to crosstalk between GH and insulin signaling pathways. Our objective was to characterize time course changes in signaling pathways for GH and insulin in human skeletal muscle in vivo following GH exposure in the presence and absence of an oral glucose load.Eight young men were studied in a single-blinded randomized crossover design on 3 occasions: 1) after an intravenous GH bolus 2) after an intravenous GH bolus plus an oral glucose load (OGTT), and 3) after intravenous saline plus OGTT. Muscle biopsies were taken at t = 0, 30, 60, and 120. Blood was sampled at frequent intervals for assessment of GH, insulin, glucose, and free fatty acids (FFA).GH increased AUC(glucose) after an OGTT (p<0.05) without significant changes in serum insulin levels. GH induced phosphorylation of STAT5 independently of the OGTT. Conversely, the OGTT induced acute phosphorylation of the insulin signaling proteins Akt (ser(473) and thr(308)), and AS160.The combination of OGTT and GH suppressed Akt activation, whereas the downstream expression of AS160 was amplified by GH. WE CONCLUDED THE FOLLOWING: 1) A physiological GH bolus activates STAT5 signaling pathways in skeletal muscle irrespective of ambient glucose and insulin levels 2) Insulin resistance induced by GH occurs without a distinct suppression of insulin signaling proteins 3) The accentuation of the glucose-stimulated activation of AS 160 by GH does however indicate a potential crosstalk between insulin and GH.ClinicalTrials.gov NCT00477997

Assessment of contractility in intact ventricular cardiomyocytes using the dimensionless ‘Frank–Starling Gain’ index

This paper briefly recapitulates the Frank–Starling law of the heart, reviews approaches to establishing diastolic and systolic force–length behaviour in intact isolated cardiomyocytes, and introduces a dimensionless index called ‘Frank–Starling Gain’, calculated as the ratio of slopes of end-systolic and end-diastolic force–length relations. The benefits and limitations of this index are illustrated on the example of regional differences in Guinea pig intact ventricular cardiomyocyte mechanics. Potential applicability of the Frank–Starling Gain for the comparison of cell contractility changes upon stretch will be discussed in the context of intra- and inter-individual variability of cardiomyocyte properties

Limit-Fed, High-Energy Diets Can Achieve Improved Feed Conversion Rates Without Compromising Rate of Gain When Compared to Conventional High Roughage Diets

Objective: Compare and determine the effects on animal performance between a conventional high roughage diet and a limit-fed, high energy diet during the receiving and growing phase. Study Description: Crossbred heifer calves (n = 418) originating from Texas and New Mexico were used to determine performance when limit-fed a high energy diet initially offered at 85% of feed intakes from cattle fed a conventional high roughage diet ad libitum at the Kansas State University Beef Stocker Unit. The Bottom Line: Limit-feeding a high energy diet consisting primarily of dry-rolled corn and Sweet Bran (Cargill Animal Nutrition, Blair, NE) can improve rate of gain while significantly decreasing dry matter consumption over conventional high roughage diets fed ad libitum, and cattle exhibit greater muscling and fat deposition