Early pregnancy peripheral blood gene expression and risk of preterm delivery: a nested case control study

<p>Abstract</p> <p>Background</p> <p>Preterm delivery (PTD) is a significant public health problem associated with greater risk of mortality and morbidity in infants and mothers. Pathophysiologic processes that may lead to PTD start early in pregnancy. We investigated early pregnancy peripheral blood global gene expression and PTD risk.</p> <p>Methods</p> <p>As part of a prospective study, ribonucleic acid was extracted from blood samples (collected at 16 weeks gestational age) from 14 women who had PTD (cases) and 16 women who delivered at term (controls). Gene expressions were measured using the GeneChip^®Human Genome U133 Plus 2.0 Array. Student's T-test and fold change analysis were used to identify differentially expressed genes. We used hierarchical clustering and principle components analysis to characterize signature gene expression patterns among cases and controls. Pathway and promoter sequence analyses were used to investigate functions and functional relationships as well as regulatory regions of differentially expressed genes.</p> <p>Results</p> <p>A total of 209 genes, including potential candidate genes (e.g. PTGDS, prostaglandin D2 synthase 21 kDa), were differentially expressed. A set of these genes achieved accurate pre-diagnostic separation of cases and controls. These genes participate in functions related to immune system and inflammation, organ development, metabolism (lipid, carbohydrate and amino acid) and cell signaling. Binding sites of putative transcription factors such as EGR1 (early growth response 1), TFAP2A (transcription factor AP2A), Sp1 (specificity protein 1) and Sp3 (specificity protein 3) were over represented in promoter regions of differentially expressed genes. Real-time PCR confirmed microarray expression measurements of selected genes.</p> <p>Conclusions</p> <p>PTD is associated with maternal early pregnancy peripheral blood gene expression changes. Maternal early pregnancy peripheral blood gene expression patterns may be useful for better understanding of PTD pathophysiology and PTD risk prediction.</p

An Experimental Study of Single and Multiple Turbulent Buoyant Jets in Crossflow

270 p.Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1984.The phenomenon of turbulent, buoyant jets in crossflow is a fundamental fluid mechanics problem with many application areas, including jets discharged from natural and mechanical draft cooling towers. Buoyant jets have been studied for many years, and as a result there exists a large body of literature on this and other related topics. An extensive review of this literature showed that there was a need for an improved laboratory simulation technique and quantitative data on both single and multiple buoyant jets.A new buoyant jet simulation technique is developed which uses a vertically downward discharge of cold nitrogen gas into a wind tunnel with discharge temperature of the jet ranging between -30(DEGREES)C and -150(DEGREES)C. This technique is capable of simulating the puff-like nature of prototype cooling tower plumes as evidenced by flow visualization which is inherent in this method. A large body of data are reported for both single and multiple jets covering a wide range of parameters. Single jet data are obtained for discharge densimetric Frounde number F varying between 0.2 and 2.4 and crossflow-to-exit velocity ratio k varying between 0.2 and 11.7. The multiple jet data are reported for three angles of orientation (theta) with F values varying between 1.1 and 2.7 and k between 0.5 and 3.The single jet results show that trajectory is very sensitive to k. The discharge densimetric Froude number also affects the trajectory but to a lesser extent. Temperature decay, on the other hand, is more sensitive to F than it is to k. An increase in k has the effect of lowering the trajectory of the jet. The isotherm downwind extension, which is a measure of effective jet mixing, increases with k for k less than the critical value k(,*). For k &gt; k(,*) this trend reverses, indicating a more enhanced jet mixing. Physically, k(,*) indicates onset of jet/wake interaction. In highly buoyant jets, jet/wake interaction is prolonged until very high k.The multiple jets show that the inline configuration ((theta) = 0 degrees) results in considerably high trajectory compared with the oblique and crossflow cases for all F and k combinations encountered in the experiments. The oblique case trajectories are consistently higher than crossflow trajectories for k k(,*) the oblique case exhibits by far the lowest trajectories. Two mechanisms are identified for having a key role in the behavior of multiple buoyant jets, these are: (a) jet shielding and (b) jet/wake interaction.U of I OnlyRestricted to the U of I community idenfinitely during batch ingest of legacy ETD

Film Cooling on a Modern HP Turbine Blade: Part IV -- Compound-Angle Shaped Holes

ABSTRACT The performance and physics of film cooling with compoundangle shaped holes on a modern high-pressure turbine airfoil is studied in detail using state-of-the-art computational simulations. Computations model high-speed single-airfoil-passage cascade experiments, and computational results show good agreement with experimental data. Evaluation of physics includes examination of flow features and adiabatic effectiveness. The blowing ratios (M) simulated on the pressure surface (PS) of the blade are 1.5, 3.0, and 4.5, with a single density ratio of 1.52. On the pressure surface the dominant mechanism affecting coolant behavior is vorticity, which increasingly tucks hot crossflow under the coolant as the blowing ratio increases. Thus at high blowing ratios, a lower percentage of the coolant provides thermal protection for the blade until the vortices dissipate far downstream. Also, the vortex structures cause large lateral temperature gradients despite the lateral motion of the flow induced by the compound-angle injection. The dominance of vorticity can be attributed to poor diffusion of the coolant inside the diffuser of the film hole. On the suction surface (SS), the simulated blowing ratios are 1.0, 1.5, and 2.0, with a single density ratio of 1.52. Pressure gradients normal to the SS result in the flow pushing the coolant onto the blade. Also, vorticity is less dominant since diffusion of coolant inside the film hole is better due to low blowing ratios and due to a hole metering section that is almost 3 times longer than that of the PS hole. Hot crossflow ingestion into the film hole is observed at M=2.0. Ingested crossflow causes heating of the surface inside the hole that extends down to the end of the hole metering section, where the surface temperatures are approximately equal to an average of the crossflow and coolant temperatures. These results demonstrate the inadequacy of 1-D, empirical design tools and demonstrate the need for a validated CFD-based film cooling methodology. NOMENCLATURE CASH compound-angle shaped holes C P pressure coefficient = (P-P ¥ )/(r ¥ v ¥ 2 /2

A Detailed Analysis of Film Cooling Physics, Part IV: Compound-Angle Injection With Shaped Holes,”

The flow physics of film cooling with compound-angle shaped holes is documented for realistic gas turbine parameters. Fo

Film Cooling on a Modern HP Turbine Blade: Part II -- Compound-Angle Round Holes

ABSTRACT A well-tested computational methodology and a companion experimental study are used to analyze the physics of compoundangle, cylindrical-hole film cooling on the pressure and suction surfaces of a modern high-pressure turbine airfoil. A single-passage cascade (SPC) is used to model the blade passage flow experimentally and computationally. Realistic engine conditions, including transonic flow, high turbulence levels, and a nominal density ratio of 1.52, are used to examine blowing ratios of 1.0, 1.5, and 2.0 on the suction surface (SS) and 1.5, 3.0, and 4.5 on the pressure surface (PS). The predicted results agree with experimental trends, and differences are explained in terms of known deficiencies in the turbulence treatment. The mean-flow physics downstream of coolant injection are influenced primarily by a single dominant vortex that entrains coolant and mainstream fluid, and by the effect of convex (SS) or concave (PS) curvature on the coolant jet

Film Cooling on a Modern HP Turbine Blade: Part III -- Axial Shaped Holes

ABSTRACT A well-tested computational methodology and high-quality data from a companion experimental study are used to analyze the physics of axial-injected, shaped-hole film cooling on the pressure and suction surfaces of a modern high-pressure turbine blade. Realistic engine conditions, including transonic flow, high turbulence levels, and a nominal density ratio of 1.52, are used to examine blowing ratios of 1.0, 1.5, and 2.0 on the suction surface (SS) and 1.5, 3.0, and 4.5 on the pressure surface (PS). SS results show excellent film-cooling performance with the hole shaping, but massive hot crossflow ingestion is found using similar hole shaping on the PS. Primary mechanisms governing the near and far-field cooling effectiveness and crossflow ingestion are identified, including: (1) the nature of the coolant entry into the film hole; (2) location of hole shaping relative to major coolant flow characteristics; and (3) susceptibility of lowmomentum fluid to pressure gradients. Changes in blowing ratio, while not introducing new physical mechanisms, significantly alter the extent to which the mechanisms already present affect the flow. These effects are highly non-linear for both SS and PS geometries, highlighting the inadequacy of one-dimensional design practices and the potential usefulness of CFD as a predictive tool