1,394 research outputs found
An analysis for the sound field produced by rigid wide cord dual rotation propellers of high solidarity in compressible flow
An unsteady lifting service theory for the counter-rotating propeller is presented using the linearized governing equations for the acceleration potential and representing the blades by a surface distribution of pulsating acoustic dipoles distributed according to a modified Birnbaum series. The Birnbaum series coefficients are determined by satisfying the surface tangency boundary conditions on the front and rear propeller blades. Expressions for the combined acoustic resonance modes of the front prop, the rear prop and the combination are also given
Recommended from our members
Multiple Phases of Chondrocyte Enlargement Underlie Differences in Skeletal Proportions
Even a casual pass through the great halls of mammals in the world’s natural history museums highlights the wide diversity of skeletal proportions that allow us to distinguish between species even when reduced to their calcified components. Similarly each individual is comprised of a variety of bones of differing lengths. The largest contribution to the lengthening of a skeletal element, and to the differential elongation of elements, comes from a dramatic increase in the volume of hypertrophic chondrocytes in the growth plate as they undergo terminal differentiation1–7. Despite this recognized importance, the mechanisms of chondrocyte volume enlargement have remained a mystery8–11. Here we use quantitative phase microscopy12 to show that chondrocytes undergo three distinct phases of volume increase, including a phase of massive cell swelling in which the cellular dry mass is significantly diluted. In light of the tight fluid regulatory mechanisms known to control volume in many cell types13, this stands as a remarkable mechanism for increasing cell size and regulating growth rate. It is, however, the duration of the final phase of volume enlargement by proportional dry mass increase at low density that varies most between rapidly and slowly elongating growth plates. Moreover, we find that this third phase is locally regulated through an Insulin-like Growth Factor-dependent mechanism. This study provides a framework for understanding how skeletal size is regulated and for exploring how cells sense, modify, and establish a volume set point
Effect of extraction methods on physicochemical, nutritional, antinutritional, antioxidant and antimicrobial activity of Moringa (Moringa oleifera Lam.) seed kernel oil
The effect of three different extraction methods, namely supercritical CO2, soxhlet and solvent methods on the yield, efficiency, physico-chemical properties, nutritional, anti-nutritional composition, antimicrobial and antioxidant activities of moringa (Moringa oleifera Lam.) seed kernel oil was investigated in this study. Oil extraction for SC-CO2 were 37.76 g/100g and 98.43%, observed to be higher than those of soxhlet extraction (29.12 g/100g and 76.29%), and significantly lower than solvent extraction (22.12 g/100g and 57.99%). The physico-chemical composition of the oils showed considerable variation among the extraction methods. The SC-CO2 extracted oil was found to be of superior quality, showing negligible thermal degradation and exhibited significantly (p<0.01) higher nutritional and antioxidant activity and lower anti-nutritional composition than the soxhlet and solvent extracted oils. Oils produced by SC-CO2 and soxhlet extraction methods had antimicrobial activities higher than solvent extracted oil. SCCO2 extracted oil was found to have maximum number of bioactive compounds (14 compounds) followed by solvent (8 compounds) and soxhlet (4 compounds) extracted oil. The results of the study demonstrated that SC-CO2 would be a promising process for the extraction of moringa seed kernel oil of premium quality
Raman Spectroscopy Provides a Powerful Diagnostic Tool for Accurate Determination of Albumin Glycation
We present the first demonstration of glycated albumin detection and quantification using Raman spectroscopy without the addition of reagents. Glycated albumin is an important marker for monitoring the long-term glycemic history of diabetics, especially as its concentrations, in contrast to glycated hemoglobin levels, are unaffected by changes in erythrocyte life times. Clinically, glycated albumin concentrations show a strong correlation with the development of serious diabetes complications including nephropathy and retinopathy. In this article, we propose and evaluate the efficacy of Raman spectroscopy for determination of this important analyte. By utilizing the pre-concentration obtained through drop-coating deposition, we show that glycation of albumin leads to subtle, but consistent, changes in vibrational features, which with the help of multivariate classification techniques can be used to discriminate glycated albumin from the unglycated variant with 100% accuracy. Moreover, we demonstrate that the calibration model developed on the glycated albumin spectral dataset shows high predictive power, even at substantially lower concentrations than those typically encountered in clinical practice. In fact, the limit of detection for glycated albumin measurements is calculated to be approximately four times lower than its minimum physiological concentration. Importantly, in relation to the existing detection methods for glycated albumin, the proposed method is also completely reagent-free, requires barely any sample preparation and has the potential for simultaneous determination of glycated hemoglobin levels as well. Given these key advantages, we believe that the proposed approach can provide a uniquely powerful tool for quantification of glycation status of proteins in biopharmaceutical development as well as for glycemic marker determination in routine clinical diagnostics in the future.National Center for Research Resources (U.S.) (Grant No. P41-RR02594)Massachusetts Institute of Technology. Laser Biomedical Research Cente
Intra-aortic balloon counterpulsation in US and non-US centres: results of the Benchmark® Registry
Aims To examine differences in patient characteristics and outcomes in 19 636 patients enrolled in the USA and 3027 patients enrolled in other countries undergoing intra-aortic balloon pump (IABP) counterpulsation. Methods and results Indications for IABP use; a larger percentage of US patients were identified as ‘early support and stabilization for angiography or angioplasty' (21.1% US vs 11.8% non-US), and ‘pre-operative support for high-risk CABG' (15.9% vs 6.6%). A smaller percentage of US patients vs non-US patients were identified as ‘weaning from cardiopulmonary bypass' (14.3% vs 28.2%), and ‘refractory ventricular failure' (6.2% vs 9.8%). One out of five patients in both groups was listed as ‘cardiogenic shock' (18.9% US vs 20.2% non-US). All cause, risk-adjusted, in-hospital mortality (20.1% vs 28.7%; P<0.001), and mortality with IABP in place (10.8% vs 18.0%; P<0.001) were lower at US vs non-US sites. In both US and non-US institutions, IABP associated complication rates, such as IABP-related mortality (0.05% vs 0.07%), major limb ischaemia (0.9% vs 0.8%), and severe bleeding (0.9% vs 0.8%), were low. Conclusions IABP counterpulsation is deployed at an earlier clinical stage in US patients. Mortality rates are higher for non-US patients, particularly for patients with non-surgery cardiac interventions, even after adjusting for risk factors. Complication rates were low. Physicians should therefore not be reluctant to use IABP in high-risk patients undergoing cardiac procedure
Identification of manganese superoxide dismutase from Sphingobacterium sp. T2 as a novel bacterial enzyme for lignin oxidation
The valorisation of aromatic heteropolymer lignin is an important unsolved problem in the development of a biomass-based biorefinery, for which novel high-activity biocatalysts are needed. Sequencing of the genomic DNA of lignin-degrading bacterial strain Sphingobacterium sp. T2 revealed no matches to known lignin-degrading genes. Proteomic matches for two manganese superoxide dismutase proteins were found in partially purified extracellular fractions. Recombinant MnSOD1 and MnSOD2 were both found to show high activity for oxidation of Organosolv and Kraft lignin, and lignin model compounds, generating multiple oxidation products. Structure determination revealed that the products result from aryl-Cα and Cα-Cβ bond oxidative cleavage and O-demethylation. The crystal structure of MnSOD1 was determined to 1.35 Å resolution, revealing a typical MnSOD homodimer harbouring a 5-coordinate trigonal bipyramidal Mn(II) centre ligated by three His, one Asp and a water/hydroxide in each active site. We propose that the lignin oxidation reactivity of these enzymes is due to the production of hydroxyl radical, a highly reactive oxidant. This is the first demonstration that MnSOD is a microbial lignin-oxidising enzyme
Implementation of Basal-Bolus Therapy in Type 2 Diabetes:A Randomized Controlled Trial Comparing Bolus Insulin Delivery Using an Insulin Patch with an Insulin Pen
Background: Barriers to mealtime insulin include complexity, fear of injections, and lifestyle interference. This multicenter, randomized controlled trial evaluated efficacy, safety, and self-reported outcomes in adults with type 2 diabetes, inadequately controlled on basal insulin, initiating and managing mealtime insulin with a wearable patch versus an insulin pen. Methods: Adults with type 2 diabetes (n = 278, age: 59.2 +/- 8.9 years), were randomized to patch (n = 139) versus pen (n = 139) for 48 weeks, with crossover at week 44. Baseline insulin was divided 1:1 basal: bolus. Using a pattern-control logbook, subjects adjusted basal and bolus insulin weekly using fasting and premeal glucose targets. Results: Glycated hemoglobin (HbA1c) change (least squares mean +/- standard error) from baseline to week 24 (primary endpoint) improved (P \u3c 0.0001) in both arms, -1.7% +/- 0.1% and -1.6% +/- 0.1% for patch and pen (-18.6 +/- 1.1 and -17.5 +/- 1.1 mmol/mol), and was maintained at 44 weeks. The coefficient of variation of 7-point self-monitoring blood glucose decreased more (P = 0.02) from baseline to week 44 for patch versus pen. There were no differences in adverse events, including hypoglycemia (three severe episodes per arm), and changes in weight and insulin doses. Subject-reported treatment satisfaction, quality of life, experience ratings at week 24, and device preferences at week 48 significantly favored the patch. Most health care providers preferred patch for mealtime insulin. Conclusions: Bolus insulin delivered by patch and pen using an algorithm-based weekly insulin dose titration significantly improved HbA1c in adults with type 2 diabetes, with improved subject and health care provider experience and preference for the patch
Harmonic Sums and Mellin Transforms up to two-loop Order
A systematic study is performed on the finite harmonic sums up to level four.
These sums form the general basis for the Mellin transforms of all individual
functions of the momentum fraction emerging in the quantities of
massless QED and QCD up to two--loop order, as the unpolarized and polarized
splitting functions, coefficient functions, and hard scattering cross sections
for space and time-like momentum transfer. The finite harmonic sums are
calculated explicitly in the linear representation. Algebraic relations
connecting these sums are derived to obtain representations based on a reduced
set of basic functions. The Mellin transforms of all the corresponding Nielsen
functions are calculated.Comment: 44 pages Latex, contract number adde
Recommended from our members
Protein and molecular characterization of a clinically compliant amniotic fluid stem cell derived extracellular vesicle fraction capable of accelerating muscle regeneration through the enhancement of angiogenesis
The secretome of human amniotic fluid stem cells (AFSC) has great potential as a therapeutic agent in regenerative medicine. However it must be produced in a clinically compliant manner before it can be used in humans. Here we developed a means of producing a biologically active secretome from AFSCs that is free of all exogenous molecules. We demonstrate that the full secretome is capable of promoting stem cell proliferation, migration and protection of cells against senescence. Furthermore, it has significant anti-inflammatory properties. Most importantly we show that it promotes tissue regeneration in a model of muscle damage. We then demonstrate that the secretome contains extracellular vesicles (EV) that harbour much but not all the biological activity of the whole secretome. Proteomic characterisation of the EV and free secretome fraction show the presence of numerous molecules specific to each fraction that could be key regulators of tissue regeneration. Intriguingly we show that the EVs only contain miRNA and not mRNA. This suggests tissue regeneration in the host is mediated by the action of EVs modifying existing, rather than the imposition of new, signalling pathways. The EVs harbour significant anti-inflammatory activity as well as promoting angiogenesis; the latter may be the mechanistic explanation for their ability to promote muscle regeneration after cardiotoxin injury
A graphene-based physiometer array for the analysis of single biological cells
A significant advantage of a graphene biosensor is that it inherently represents a continuum of independent and aligned sensor-units. We demonstrate a nanoscale version of a micro-physiometer – a device that measures cellular metabolic activity from the local acidification rate. Graphene functions as a matrix of independent pH sensors enabling subcellular detection of proton excretion. Raman spectroscopy shows that aqueous protons p-dope graphene – in agreement with established doping trajectories, and that graphene displays two distinct pKa values (2.9 and 14.2), corresponding to dopants physi- and chemisorbing to graphene respectively. The graphene physiometer allows micron spatial resolution and can differentiate immunoglobulin (IgG)-producing human embryonic kidney (HEK) cells from non-IgG-producing control cells. Population-based analyses allow mapping of phenotypic diversity, variances in metabolic activity, and cellular adhesion. Finally we show this platform can be extended to the detection of other analytes, e.g. dopamine. This work motivates the application of graphene as a unique biosensor for (sub)cellular interrogation.National Cancer Institute (U.S.) (Cancer Center Support (Core) Grant P30-CA14051)U.S. Army Research LaboratoryUnited States. Army Research Office. Institute for Soldier Nanotechnologies (Contract W911NF-13-D-0001)National Institute for Biomedical Imaging and Bioengineering (U.S.) (Grant P41EB015871-27)Skolkovo Institute of Science and Technolog
- …
