EXPLORATION OF MICROPLASTIC FIBERS TRANSPORT DYNAMICS IN POROUS MEDIA USING A COMBINATION OF PHYSICAL EXPERIMENTS AND NUMERICAL SIMULATIONS

The existence of microplastics (MPs) in the environment has been a growing concern for two and a half decades, having now been found in remote areas, ocean sediment, deserts, and mountain peaks. MPs in the environment are a concern because they can impact soil properties and organisms. Research has determined that MPs can affect aquatic organisms in two forms: 1.) mechanical- MPs can attach to the body of the organism and impact their movement and 2.) chemical- the leaching of chemicals from the MPs can be absorbed by the organisms, both of these impact forms can lead organisms to experience inflammation, stress, death, and reproduction decline. The impact on human health is limited but assumed to see the same impacts as aquatic organisms. The largest MP type by mass found in the environment is microplastic fiber (MPF). Scientists understand where MPs come from and where they end up (large-scale movement), the missing aspect is how they move. This research gap is missing due to the transport mechanics occur at the pore scale which is difficult to capture. The mechanisms of MPFs transport have been proposed numerically but have not been validated. This research collected MPF transport data in a 2D laboratory model to understand the transport dynamics in porous media of three different lengths 0.3, 0.5, 0.8 cm and microbeads to act as a passive tracer, modeling MPF transport with existing simulation tools (ADE equation) and validate the only MPF distributed simulation model to date. Videos captured the trajectory of the fiber and beads, and the trajectory data was used to generate breakthrough curves. The experimental data found that fibers tumble/roll during their transport through the model, that fibers traveled much slower than expected, and longer fibers would travel slower. It was observed that fibers would have an abrupt change in velocity and became stuck then re-mobilized. This paper refers to this dynamic as “trapping”. Comparisons tothe ADE (i.e. advection-dispersion models) equation and the distributed simulation model (DSM) were unable to simulate MPF transport, which leads to the question of what dynamics are missing from the models. ADE simulation was unable to capture the correct shape of the curve, with particles arriving sooner than the experiments. The DSM can simulate the transport of beads but nothing else. This suggests that the missing dynamics result in a retention or trapping process, but the design of these experiments cannot determine the precise mechanism. However, two upscaled representations of the trapping process were able to significantly improve the agreement of the experimental and numerical results

Modeling and Design Optimization of Multifunctional Membrane Reactors for Direct Methane Aromatization

Due to the recent increase of natural gas production in the U.S., utilizing natural gas for higher-value chemicals has become imperative. Direct methane aromatization (DMA) is a promising process used to convert methane to benzene, but it is limited by low conversion of methane and rapid catalyst deactivation by coking. Past work has shown that membrane separation of the hydrogen produced in the DMA reactions can dramatically increase the methane conversion by shifting the equilibrium toward the products, but it also increases coke production. Oxygen introduction into the system has been shown to inhibit this coke production while not inhibiting the benzene production. This thesis introduces a novel mathematical model and design to employ both methods in a multifunctional membrane reactor to push the DMA process into further viability. Multifunctional membrane reactors, in this case, are reactors where two different separations occur using two differently selective membranes, on which no systems studies have been found. The proposed multifunctional membrane design incorporates a hydrogen-selective membrane on the outer wall of the reaction zone, and an inner tube filled with air flow surrounded by an oxygen-selective membrane in the middle of the reactor. The design is shown to increase conversion via hydrogen removal by around 100%, and decrease coke production via oxygen addition by 10% when compared to a tubular reactor without any membranes. Optimization studies are performed to determine the best reactor design based on methane conversion, along with coke and benzene production. The obtained optimal design considers a small reactor (length = 25 cm, diameter of reaction tube = 0.7 cm) to subvert coke production and consumption of the product benzene as well as a high permeance (0.01 mol/s.m2.atm1/4) through the hydrogen-permeable membrane. An independent optimal design of the oxygen permeable membrane calls for low oxygen flux (permeance = 2.09 mol/s.m 2.atm1/4, diameter of air tube = 0.5 cm) so oxidative reactions do not inhibit benzene production. This modeling and design approach sets the stage for guiding further development of multifunctional membrane reactor models and designs for natural gas utilization and other chemical reaction systems

Modeling and Design Optimization of Multifunctional Membrane Reactors for Direct Methane Aromatization

Due to the recent increase of natural gas production in the U.S., utilizing natural gas for higher-value chemicals has become imperative. Direct methane aromatization (DMA) is a promising process used to convert methane to benzene, but it is limited by low conversion of methane and rapid catalyst deactivation by coking. Past work has shown that membrane separation of the hydrogen produced in the DMA reactions can dramatically increase the methane conversion by shifting the equilibrium toward the products, but it also increases coke production. Oxygen introduction into the system has been shown to inhibit this coke production while not inhibiting the benzene production. This paper introduces a novel mathematical model and design to employ both methods in a multifunctional membrane reactor to push the DMA process into further viability. Multifunctional membrane reactors, in this case, are reactors where two different separations occur using two differently selective membranes, on which no systems studies have been found. The proposed multifunctional membrane design incorporates a hydrogen-selective membrane on the outer wall of the reaction zone, and an inner tube filled with airflow surrounded by an oxygen-selective membrane in the middle of the reactor. The design is shown to increase conversion via hydrogen removal by around 100%, and decrease coke production via oxygen addition by 10% when compared to a tubular reactor without any membranes. Optimization studies are performed to determine the best reactor design based on methane conversion, along with coke and benzene production. The obtained optimal design considers a small reactor (length = 25 cm, diameter of reaction tube = 0.7 cm) to subvert coke production and consumption of the product benzene as well as a high permeance (0.01 mol/s·m2·atm1/4) through the hydrogen-permeable membrane. This modeling and design approach sets the stage for guiding further development of multifunctional membrane reactor models and designs for natural gas utilization and other chemical reaction systems

Convergent Validity of a Single Question with Multiple Classification Options for Depression Screening in Medical Settings

The purpose of this study was to assess the convergent validity of a single depression question with multiple classification options for depression screening. Participants were 40 medical inpatients. The age range of our sample was 18 to 85 years (M = 56.15, SD = 17.66). A clinical interview and the BDI-II were administered. The correlation between patients’ self-rating classification of depression and their BDI-II classification was significant, rs(38) = .90, p < .01. Follow-up repeated-measures chi-square revealed a statistically significant association between BDI-II classification and patients’ self-rating classification, χ2(9, N = 40) = 47.79, p < .005. Significant positive standardized residuals revealed a clear linear relationship between BDI-II and patient self-rating classifications. Our data support the use of a single depression question with multiple classification options as a useful and valid means of quickly screening for the presence of depression by frontline health care professionals

Upregulation of nitric oxide synthase in mice with severe hypoxia-induced pulmonary hypertension

BACKGROUND: The importance of nitric oxide (NO) in hypoxic pulmonary hypertension has been demonstrated using nitric oxide synthase (NOS) knockout mice. In that model NO from endothelial NOS (eNOS) plays a central role in modulating pulmonary vascular tone and attenuating hypoxic pulmonary hypertension. However, the normal regulation of NOS expression in mice following hypoxia is uncertain. Because genetically engineered mice are often utilized in studies of NO, we conducted the present study to determine how hypoxia alters NOS expression in wild-type mice. METHOD: Mice were exposed to sea level, ambient conditions (5280 feet) or severe altitude (17,000 feet) for 6 weeks from birth, and hemodynamics and lung NOS expression were assessed. RESULTS: Hypoxic mice developed severe pulmonary hypertension (right ventricular systolic pressure [RVsP] 60 mmHg) as compared with normoxic mice (27 mmHg). Using quantitative reverse-transcription PCR, it was found that expressions of eNOS and inducible NOS (iNOS) increased 1.5-fold and 3.5-fold, respectively, in the lung. In addition, the level of lung eNOS protein was increased, neuronal NOS (nNOS) protein was unchanged, and iNOS was below the limit of detection. Immunohistochemistry demonstrated no change in lung iNOS or nNOS staining in either central or peripheral areas, but suggested increased eNOS in the periphery following hypoxia. CONCLUSION: In mice, hypoxia is associated with increases in lung eNOS, possibly in iNOS, but not in nNOS; this suggests that the pattern of lung NOS expression following hypoxia must be considered in studies using genetically engineered mice

A Racial/Ethnic Performance Disparity on the Facial Recognition Test

The Facial Recognition Test is a widely used psychometric instrument for assessing visuoperceptual functioning. Only two prior studies have examined the effects of race/ethnicity on this test. Given that the United States has become more culturally diverse since the creation of the test, it is important to re-visit the effects of this demographic variable on performance. Participants were 75 males and 75 females between the ages of 18 and 43 years (M = 21.91, SD = 5.33). Racial/ethnic categories utilized by the U.S. Census Bureau were equally represented. No gender differences were observed. The race/ethnicity main effect was significant. The gender x race/ethnicity interaction was not significant. The data revealed a clear racial/ethnic performance disparity on the Facial Recognition Test

Content Validity of the Geriatric Depression Scale in Inpatient Health Care Settings

The content validity of the Geriatric Depression Scale (GDS) for use in inpatient health care settings was evaluated. Clinical experience has shown that one or more questions may not be appropriate in such settings. These questions ask about behaviors or feelings with which the examinee may not be able to identify with because they have been in an inpatient setting during the past week. Twenty-five Subject Matter Experts (SMEs) evaluated the GDS-30 as to whether each item appropriately assesses the construct of depression for inpatients in a medical care setting. SMEs were identified by an online search of the Florida Division of Medical Quality Assurance database; inclusion criteria are presented. Nineteen SMEs held a Ph.D. and six held a Psy.D. Years of post-licensure practice experience ranged from 10 to 48 years with a mean of 23.12 years (SD = 10.07). Using the Content Validity Ratio, four questions emerged as inappropriate (statistically significant at, or below, an alpha level of .025). The lack of content validity of these questions necessitates their omission when psychometrically assessing depression in elderly inpatients. Recommended revised cutoff values are presented. Utilizing the recommended modification to the GDS presented here should reduce false positives when psychometrically assessing depression in elderly inpatients

Effect of hypoxia and Beraprost sodium on human pulmonary arterial smooth muscle cell proliferation: the role of p27kip1

<p>Abstract</p> <p>Background</p> <p>Hypoxia induces the proliferation of pulmonary arterial smooth muscle cell (PASMC) <it>in vivo </it>and <it>in vitro</it>, and prostacyclin analogues are thought to inhibit the growth of PASMC. Previous studies suggest that p27^kip1, a kind of cyclin-dependent kinase inhibitor, play an important role in the smooth muscle cell proliferation. However, the mechanism of hypoxia and the subcellular interactions between p27^kip1and prostacyclin analogues in human pulmonary arterial smooth muscle cell (HPASMC) are not fully understood.</p> <p>Methods</p> <p>We investigated the role of p27^kip1in the ability of Beraprost sodium (BPS; a stable prostacyclin analogue) to inhibit the proliferation of HPASMC during hypoxia. To clarify the biological effects of hypoxic air exposure and BPS on HPASMC, the cells were cultured in a hypoxic chamber under various oxygen concentrations (0.1–21%). Thereafter, DNA synthesis was measured as bromodeoxyuridine (BrdU) incorporation, the cell cycle was analyzed by flow cytometry with propidium iodide staining. The p27^kip1mRNA and protein expression and it's stability was measured by real-time RT-PCR and Western blotting. Further, we assessed the role of p27^kip1in HPASMC proliferation using p27^kip1gene knockdown using small interfering RNA (siRNA) transfection.</p> <p>Results</p> <p>Although severe hypoxia (0.1% oxygen) suppressed the proliferation of serum-stimulated HPASMC, moderate hypoxia (2% oxygen) enhanced proliferation in accordance with enhanced p27^kip1protein degradation, whereas BPS suppressed HPASMC proliferation under both hypoxic and normoxic conditions by suppressing p27^kip1degradation with intracellular cAMP-elevation. The 8-bromo-cyclic adenosine monophosphate (8-Br-cAMP), a cAMP analogue, had similar action as BPS in the regulation of p27^kip1. Moderate hypoxia did not affect the stability of p27^kip1protein expression, but PDGF, known as major hypoxia-induced growth factors, significantly decreased p27^kip1protein stability. We also demonstrated that BPS and 8-Br-cAMP suppressed HPASMC proliferation under both hypoxic and normoxic conditions by blocking p27^kip1mRNA degradation. Furthermore, p27^kip1gene silencing partially attenuated the effects of BPS and partially restored hypoxia-induced proliferation.</p> <p>Conclusion</p> <p>Our study suggests that moderate hypoxia induces HPASMC proliferation, which is partially dependent of p27^kip1down-regulation probably <it>via </it>the induction of growth factors such as PDGF, and BPS inhibits both the cell proliferation and p27^kip1mRNA degradation through cAMP pathway.</p

Riparian Research and Management: Past, Present, Future: Volume 1

Fifty years ago, riparian habitats were not recognized for their extensive and critical contributions to wildlife and the ecosystem function of watersheds. This changed as riparian values were identified and documented, and the science of riparian ecology developed steadily. Papers in this volume range from the more mesic northwestern United States to the arid Southwest and Mexico. More than two dozen authors—most with decades of experience—review the origins of riparian science in the western United States, document what is currently known about riparian ecosystems, and project future needs. Topics are widespread and include: interactions with fire, climate change, and declining water; impacts from exotic species; unintended consequences of biological control; the role of small mammals; watershed response to beavers; watershed and riparian changes; changes below large dams; water birds of the Colorado River Delta; and terrestrial vertebrates of mesquite bosques. Appendices and references chronicle the field’s literature, authors, “riparian pioneers,” and conferences