105 research outputs found
Role of Perivascular Adipose Tissue in Vascular Pathology and the Therapeutic Effect of Exercise
Aortic compliance is important for dampening pulsatile flow and delivery of continuous flow to the periphery. Aortic compliance is regulated by extracellular matrix composition and endothelial derived nitric oxide. Disruption of aortic endothelium or extracellular matrix can lead to the development of aortic stiffness an independent risk factor of cardiac events and mortality. Over the past decade perivascular adipose tissue (PVAT) surrounding the vasculature has come to light as an important regulator of artery function. The main focus of this dissertation is to evaluate the role PVAT surrounding the aorta in mediating endothelial relaxation in health and disease. Specifically, metabolic syndrome (MetS) and chronic stress induced depressive states.;The United States has a high prevalence of both MetS and depressive states, 34% and 17% respectively. Additionally, the co-prevalence of depressive states with MetS is common. Both MetS and depressive states are associated with vascular dysfunction, in part, mediated through an increase of pro-inflammatory cytokines and oxidative stress. Little is known about the impact of MetS on PVAT regulation of the aorta and the impact of depressive states or depressive states concomitant with MetS on PVAT is unexplored.;Aerobic exercise training is recognized to have antioxidant and anti-inflammatory properties and promotes vascular health. Exercise training has been shown to reduce aortic stiffness and reduce the risk of cardiac events and mortality. Likewise exercise treatment of MetS or depressive state yields beneficial effects and limits the vascular pathology of these disease state. However, the actions of exercise on PVAT in health and disease are poorly understood. In order to evaluate these gaps in knowledge, I purpose the following specific aims for this dissertation: 1. Determine Metabolic Syndrome\u27s impact on Thoracic Aorta PVAT and PVAT derived TNFalpha contribution to aortic dysfunction 2. Determine if UCMS impacts the regulation of PVAT on aortic function 3. Test the therapeutic effectiveness of aerobic exercise on PVAT and its regulation of aortic function.;The results of this study will establish the role of PVAT in mediating aortic dysfunction associated with MetS and depressive state. Additionally, this work will identify key disease specific mediators of PVAT regulation of aortic function. Finally, this work will establish mechanisms through which exercise mediates beneficial aortic function
Properties of Wood/recycled Textile Composite Panels
This study evaluated the potential to use recycled cotton textiles as filler and possibly reinforcement in the core of oriented strandboard (OSB) panels. Nominal 11.1-mm-thick, 686 x 686-mm OSB/textile fiber composite panels (50% surface and 50% core layers) were fabricated. Recycled textile material (0, 5, 15, 25, and 50% of the total weight percentage in the panel) was blended with mixed hardwood core strands. For each combination of wood and textile material, 10 panels were produced for a total of 50 panels. Internal bond strength, static bending strength and stiffness, water absorption, thickness swell, and nail withdrawal strength properties were evaluated. The major finding of the study indicated that compared with controls (ie panels with 0% textile material), panels with 5% recycled textiles did not have a statistically significant difference in bending strength (modulus of rupture) and elasticity (modulus of elasticity) or nail withdrawal strength. Additionally, although the controls had the greatest average thickness swell, none of the groups tested showed a statistically significant difference (p = 0.064). The study indicated that there is potential for adding 5% recycled textiles to the core of OSB panels without significantly decreasing physical or mechanical properties
Bioenergy Properties of Juvenile Hybrid Poplars and Their Parent Species
Bioenergy properties of poplar species Populus trichocarpa (PT), Populus deltoides (PD), and their hybrid were evaluated. Hybrid poplar trees from the cross between PT and PD presented different anatomic, physical, chemical, and thermal properties from their parent species. Anatomic results tended to suggest that hybrid poplar, with fewer vessels per unit area, had more resemblance to PT. Extractive content ranged from 10.64-11% for PD, PT, and first-generation hybrid poplar, whereas it varied from 8.8-9.5% for backcross offspring (BC2-BC5). PD had the greatest average lignin content of 25.6% followed by first-generation offspring and backcross offspring with lignin content of approximately 25%. Holocellulose content of hybrid poplar species was higher than that of their parent species. Observed stem/stump proximate results ranged from 72-74.7%, 25-28%, and 0.80-1.7% for volatile matter, fixed carbon, and ash content, respectively. Heating values observed along the stem were slightly higher than at the stump, ranging from 7498-8356 kJ. TGA-FTIR analysis indicated that H2, CO2, CH4, and CO were the dominant gaseous components from wood pyrolysis
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Influence of veneer roughness, lathe check, and annual ring characteristics on glue-bond performance of Douglas-fir plywood
Current lathe technology, smaller diameter logs, smaller core diameters, and
the sale of higher grade veneer for use in engineered wood products are all factors
contributing to plywood manufacturers using rougher veneer with different lathe
check characteristics. When rough veneer is encountered, plywood manufacturers
typically increase the adhesive spread rate in an attempt to achieve sufficient bonds
between veneer surfaces. However, the effectiveness of this practice has not been
clearly established. Little is known about how veneer roughness and lathe check
characteristics interact to determine glue-bond quality or how lathe checks propagate
under load while contributing to glue-bond failure. It was hypothesized that veneer
roughness, lathe check, and annual ring characteristics interact to determine plywood
glue-bond quality (i.e., wood failure percentage and load at failure). This study
investigated the influence of veneer roughness, lathe check, and annual ring
characteristics on Douglas-fir Pseudotsuga menziesii) plywood glue-bond
performance. The study also investigated the differences in glue-bond quality when samples were tested in a dry and wet (PS 1 boil method) state and prepared such that
lathe checks were pulled open or closed.
To evaluate differences in test conditions on standard glue-bond
samples, 120 blanks were cut from a Douglas-fir plywood panel and kerfed
accordingly to produce 60 open and 60 closed specimens. Out of these specimens,
half of the open samples and half of the closed samples were tested in a wet condition
and the other half in a dry condition. On each sample, ultimate failure load and
percent wood failure were recorded.
A two-way analysis of variance (ANOVA) test performed on the load at failure
results indicated that each factor (wet or dry conditioning and open or closed lathe
checks) had a statistically significant influence in load at failure, as did the interactions
of factors. Further analysis of the interactions using multiple range testing indicated a
statistically significant difference between all four groups (dry open, dry closed, wet
open, and wet closed). In terms of load at failure, dry closed exhibited the highest
average load value, followed by dry open, wet closed, and wet open, respectively. A
two-way ANOVA test indicated that each factor (i.e., wet or dry conditioning and
open or closed lathe checks) did not have any statistically significant influence on
percent wood failure nor did the interactions. In addition, multiple range testing
indicated no statistically significant difference between all four groups. To investigate the influence of veneer characteristics on glue-bond quality,
ninety veneer sheets, 12-inches by 12-inches, were separated into three visual
roughness categories; smooth, intermediate and rough. Using a laser scatter/optical
imaging system, fifteen mathematical roughness measurements were determined for five randomly selected 1-inch by 1-inch areas per sheet. The scanned veneers were
placed as center plies in 3-piy, 3-layer plywood panels and pressed using typical mill
lay-up procedures. Glue-bond specimens were prepared and tested in accordance to
PS 1-95 to evaluate adhesive bonding of the 1-inch² Results from an ANOVA test showed that there was a statistically significant
difference (p-value < 0.000 1) for average load at failure between visual roughness
categories. Two sample t-tests indicated a statistically significant difference between
average load at failure between smooth and intermediate (p-value < 0.000 1), smooth
and rough (p-value <0.0001), and intermediate and rough (p-value = 0.043). Analysis
of multiple range tests indicated a statistically significant difference for load at failure
between smooth and intermediate, and smooth and rough, but found no significant
difference between load at failure for intermediate and rough. Intermediate samples
had the highest average load, followed by the rough and smooth, respectively,
indicating that visual veneer roughness may not be a primary factor in determination
of load at failure.
Results from an ANOVA test showed that there was a significant statistical
difference (p-value < 0.000 1) for average percent wood failure between visual
roughness categories. Multiple range tests indicated a statistically significant difference between all three visual roughness groups for average percent wood failure.
In addition, two sample t-tests showed a statistically significant difference for average
percent wood failure between smooth and intermediate (p-value < 0.000 1), smooth
and rough (p-value <0.0001), and intermediate and rough (p-value 0.01). Smooth
samples had the highest average percent wood failure, followed by intermediate and
rough, respectively.
Using stepwise and all possible combination best-fit regression techniques,
load at failure was found to decrease as lathe check frequency increased. In addition,
load at failure was influenced by the number of growth rings per inch, percent
latewood in the test area, earlywood/latewood ratio, distance of second lathe check to
the saw kerf, and two distinct mathematical veneer roughness measures. Stepwise and
best-fit regression analysis showed that percent wood failure was influenced mainly by
mathematical veneer roughness measures, but was also affected by the number of
growth rings per inch, percent latewood in the test area, and percent latewood at the
tight-side glue-line. Specimen failure typically occurred by lathe checks propagating in a
tangential-radial mode, radial-tangential mode or by glue-line failure attributed to
peeling forces and/or severe surface roughness at the glue-line. In addition, both
mathematical veneer roughness measures and veneer characteristics of latewood
angle, percent latewood, lathe check frequency, growth rings per inch, number of
latewood bands, average lathe check depth, and earlywood/latewood width ratio were
found to influence elastic properties of glue-bond samples. These results suggest that
plywood manufacturers can improve glue-bond quality by monitoring and adjusting for the key veneer characteristics of roughness, lathe check occurrence, and annual
ring orientation that were found significant in the study. In particular, by reducing the
frequency of lathe checks, higher loads at failure can be obtained and by reducing
veneer roughness, percent wood failure can be increased
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Non-destructive evaluation of veneer using optical scanning and ultrasonic stress wave analysis systems
Non-destructive commercial ultrasonic grading provides laminated veneer lumber (LVL) manufacturers a means for sorting veneer based on average ultrasonic propagation time (UPT) and/or average dynamic modulus of elasticity (MOEd). While this may provide reliable estimations of modulus of elasticity (MOE), little is known about the influence of veneer defects on strength properties of veneer and LVL. It was hypothesized that inclusion of veneer defect and growth ring pattern measures, obtained via optical scanning, would improve veneer and LVL static tensile MOE and strength (Ft) property predictions. Non-destructive and destructive testing on Douglas-fir (Pseudotsuga menziesii) veneer and LVL was performed to evaluate improvements in veneer and LVL tensile MOE and Ft property predictions. Various models based solely on density, optical, and ultrasonic system measures, as well as various combinations of systems measures, were developed for individual veneer and LVL property predictions.
The integration of optical and ultrasonic measures (i.e., combined system model) best explained the variation in veneer static tensile MOE and Ft. The combined system model best predicted average LVL static tensile MOE. LVL static Ft was best predicted by using overall average veneer measures comprising the entire LVL material, rather than the average of individually predicted veneer Ft used in assembling the LVL. Specifically, the combined system model, which included various specific average defect, growth ring pattern, and MOEd measures comprising the LVL material, best explained the variation in LVL static Ft values (R2 = 0.65) as compared to all other models. Results from this study suggest improved veneer and LVL Ft predictions can be achieved by integrating the existing ultrasonic and optical systems already existing in many manufacturing facilities.
Additionally, the optical model which included average defect, growth ring, and density measurements within the LVL material better explained the variation in LVL static Ft values (R2 = 0.58), as compared to the MOEd (R2 = 0.52) and UPT (R2 = 0.31) models. As a result, the developed optical system showed promise as a suitable veneer grading system. A need was identified for future research on optically grading full-size veneer sheets and manufacturing and testing full-size LVL billets
Characterization of the Compounds Released in the Gaseous Waste Stream during the Slow Pyrolysis of Hemp (Cannabis sativa L.)
This study aims to characterize and valorize hemp residual biomass by a slow pyrolysis process. The volatile by-products of hemp carbonization were characterized by several methods (TGA, UV-VIS, TLC, Flash Prep-LC, UHPLC, QTOF-MS) to understand the pyrolysis reaction mechanisms and to identify the chemical products produced during the process. The obtained carbon yield was 29%, generating a gaseous stream composed of phenols and furans which was collected in four temperature ranges (F1 at 20–150 °C, F2 at 150–250 °C, F3 at 250–400 °C and F4 at 400–1000 °C). The obtained liquid fractions were separated into subfractions by flash chromatography. The total phenolic content (TPC) varied depending on the fraction but did not correlate with an increase in temperature or with a decrease in pH value. Compounds present in fractions F1, F3 and F4, being mainly phenolic molecules such as guaiacyl or syringyl derivatives issued from the lignin degradation, exhibit antioxidant capacity. The temperature of the pyrolysis process was positively correlated with detectable phenolic content, which can be explained by the decomposition order of the hemp chemical constituents. A detailed understanding of the chemical composition of pyrolysis products of hemp residuals allows for an assessment of their potential valorization routes and the future economic potential of underutilized biomass.This research was funded by the European Commission for funding the InnoRenew project (Grant agreement #739574 under the Horizon 2020 WIDESPREAD-2-Teaming program) and the Republic of Slovenia (investment funding from the Republic of Slovenia and the European Regional Development Fund), the European Union’s Horizon 2020 research and innovation programme under the H2020 Marie Skłodowska-Curie Actions (Grant Number 898179). Kristine Meile received funding from the ERDF Project No. 1.1.1.2/VIAA/3/19/388 “A biorefinery approach to the separation and application of the products of lignocellulose pyrolysis”. Rene Herrera received funding from Spanish Ministry of Science and Innovation and the University of the Basque Country UPV/EHU (POSTDOC: IJC2020-043740-I)
Can Deep Water Exercise Training Improve Arterial Stiffness in Women with Metabolic Syndrome?
Please refer to the pdf version of the abstract located adjacent to the title
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