905 research outputs found
Sonolytic Decomposition of Aqueous Bioxalate in the Presence of Ozone
Ultrasonic irradiation in the presence of ozone is demonstrated to be effective for the rapid oxidation of oxalic acid, bioxalate, and oxalate (H_(2)C_(2)O_(4)/HC_(2)O_(4)−/C_(2)O_(4)^2−) in aqueous solution to CO_2 and H_(2)O. The degradation rate of bioxalate exposed to “sonozone” (i.e., simultaneous ultrasonication and ozonolysis) was found to be 16-times faster than predicted by the linear addition of ozonolysis and ultrasonic irradiation rates. The hydroxyl radical (•OH) is the only oxy-radical produced that can oxidize oxalate on a relevant time-scale. Thus, plausible •OH production mechanisms are evaluated to explain the observed kinetic synergism of ultrasonication and ozonolysis toward bioxalate decomposition. •OH production via decomposition of O_3 in the cavitating bubble vapor and via the reaction of O_3 and H_(2)O_2 are considered, but kinetic estimations and experimental evidence indicate neither to be a sufficient source of •OH. A free-radical chain mechanism is proposed in which the HC_(2)O_(4)− + •OH reaction functions as a primary propagation step, while the termination occurs through the O_3 + CO_(2)•− reaction via an O-atom transfer mechanism. Kinetic simulations confirm that ozone reacts efficiently with the superoxide (O_(2)•−) ion that is produced by the reaction of O_2 and CO_(2)•− to form •OH radical, and that the reaction of O_3 + CO_(2)•− must be chain terminating. Oxalate is also readily oxidized by “peroxone” treatment (i.e., H_(2)O_2 and O_3). However, the addition of H_(2)O_2 during the course of the sonolytic ozonation of oxalic acid does not appear to increase the observed degradation rate and decreases rates at millimolar levels
MEASUREMENT OF AMORTISATION AND TAKE OFF FORCE IMPULSE DURING THE JUMP WITH BOTH LEGS
The various of jumps belong to currently used training methods. They are used to test and determine the state of training level. It is also convenient for training process management. Squat jumps and coutermovement jumps allowed to find out the parameters of slow muscle work (stretch-shortening cycle) a drop jump can help as to find out the parameters of fast stretch-shortening cycle. There exists an optimal height of drop jump in which can be reached an optimal using of amortisation impulse. All types of jumps have force impulse compound from the amortisation impulse (Ia) and takeoff impulse (It). The squat t jump is an exception. Duration, sue and shape of impulse are suitable parameters for quantifying and management of training The dynamometric board KISTLER shows the course of total force impulse and the duration of flying phase t, of the jump The total force impulse applies m Is= Ia + It (1) The height of the jump can be calculated from the -off impulse in formula h = I;/(2mZg) (2) Applied formula for height of the jump calculated from the flying phase h = 1/8(gt,2) (3) After calculation of the formula (3) we are able to substitute the height of the Jump into the formula (2) and we gain relation for the takeoff Impulse It is I, = l/2(gtfm) (4) Using substitution for relation (4) to (1) we calculate the sue of the amortization impulse. The term height of the jump is understood as the difference between the highest point of trajectory of gravity centre and gravity centre m standing (both are measured at the vertical axis). The part of the jump is also a lifting of the body on the tiptoes just before finishing the takeoff phase of the jump. The lifting has the influence for the force impulse size I,. The first contact with the ground is through tiptoes. These facts have been taken into the consideration in calculating the height of the jump from flying phase by the formula (3) and in calculating the amortization impulse I
Immunological studies of natural killer cell activity in patients with atopic dermatitis
Some patients with atopic dermatitis (AD) react abnormally to a number of cutaneous viral infections. Herpes simplex, for example can become widely disseminated with severe systemic symptoms. This susceptibility of AD patients may be due, at least in part, to deficient natural killer cell function. This study investigated the NK cell activity of AD patients using a standard four hour chromium release assay with the erythroleukaemic cell line K562 as the target cell. The NK cell activity of patients with AD was significantly reduced as compared with normal age and sex matched controls. The effect of the length of incubation time of the assay, removal of phagocytic/adherent cells and the use of target cells other than K562 on the standard four hour assay were examined. Increasing the incubation time from 4 to I8 hours and removing phagocytic/adherent cells resulted in an increase in NK cell activity, though the difference in response between patients and controls was maintained. In contrast the overall NK cell activity was reduced when target cells other then K562 were used, although the NK cell activity of the controls remained consistently higher than the patients. Atopic dermatitis is a chronic relapsing disorder and to determine whether or not NK cell activity fluctuated with disease xxiii severity NK cell activity was examined sequentially over a 12 month period in a group of patients. An inverse correlation was found between disease severity and NK cell activeity, ie. the more severe the disease the lower the NK cell activity. A strong correlation was also confirmed between clinical activity of the disease and IgE level. The reduction in NK cell activity in AD could result from either a qualitative abnormality, ie. normal numbers of effector cells with abnormal function, or a quantitative abnormality, ie. reduced numbers of effector cells. Effector cell numbers were counted using two monoclonal antibodies, HNK-1 (Leu) and Leu-11. Numbers were then correlated with function, as measTored by chromium release. Using HNK-l it appeared there was a reduction in the numbers of effector cells and this correlated v;ith the reduced activity. HNK-1 does not however, stain all NK effector cells. Using Leu-llb, which is a more specific reagent, showed normal numbers of effector cells are present in the peripheral circulation of patients as compared with controls. The reduced NK cell activity in atopic dermatitis was therefore thought to be due to a functional abnormality in the effector cell's lytic cycle. The reduction of NK cell activity could be caused by inhibitors in the serum of patients with AD. This was investigated by incubating effector cells from both AD patients, and normal controls in medium supplemented with either serum from patients with AD, normal controls or foetal calf serum (PCS). The M cell activity was estimated following either a normal four hour assay, an extended 18 hour assay or a standard four hour assay following an 18 hour preincubation in the supplemented media. Using these three protocols no significant increase was observed in the patient's effector cell activity following incubation in medium supplemented with control serum nor was there a significant decrease in control effector cell activity following incubation in medium supplemented with patients' serum. The results of this study suggest that reduced NK cell activity in AD may be related to the treatment of the disease rather than the disease itself. (Abstract shortened by ProQuest.)
Hydrogen Isotope Effects and Mechanism of Aqueous Ozone and Peroxone Decompositions
Hydrogen peroxide exalts the reactivity of aqueous ozone by reasons that remain obscure. Should H_2O_2 enhance free radical production, as it is generally believed, a chain mechanism propagated by (·OH/·O_2^-) species would account for O_3 decomposition rates in neat H_2O, ^HR_(-O_3), and in peroxone (O_3 + H_2O_2) solutions, ^(HP)R_(-O_3). We found, however, that: (1) the radical mechanism correctly predicts H^R_(-O_3) but vastly overestimates ^(HP)R_(-O_3), (2) solvent deuteration experiments preclude radical products from the (O_3 + HO_2^-) reaction. The modest kinetic isotope effect (KIE) we measure in H_2O/D_2O: ^HR_(-O_3)/^DR_(-O_3) = 1.5 ± 0.3, is compatible with a chain process driven by electron- and/or O-atom transfer processes. But the large KIE found in peroxone: ^(HP)R_(-O_3)/^(DP)R_(-O_3) = 19.6 ± 4.0, is due to an elementary (O_3 + HO_2^-) reaction involving H−O_2^- bond cleavage. Since the KIE for the hypothetical H-atom transfer: O_3 + HO_2^- →(2ℏ) HO^3· + ·O_2^-, would emerge as a KIE^(1/2) factor in the rates of the ensuing radical chain, the magnitude of the observed KIE must be associated with the hydride transfer reaction that yields a diamagnetic species: O_3 + HO_2^- HO_3^- + O_2. HO_3^-/H_2O_3 may be the bactericidal trioxide recently identified in the antibody-catalyzed addition of O_2(^1Δ_g) to H_2O
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High Power Few-Cycle Erbium Fiber Frequency Combs
Coherent optical sources from the ultraviolet (UV) to the mid-infrared (MIR) have been shown to be critical for a plethora of applications from quantitative chemical monitoring, molecular structure/function determination, to hyperspectral imaging. Optical frequency combs provide unique tools for spectroscopy due to their use in a dual comb modality, providing simultaneously large optical bandwidths with high resolution and fast data acquisition. While frequency combs readily exist in the near infrared, the UV, visible, and MIR remain a challenge for obtaining broadband comb coverage. In this dissertation I develop a simple and robust broadband frequency comb with coverage from the UV to the MIR by nonlinear frequency conversion from the near infrared, using a high power few-cycle erbium fiber frequency comb based on mature, robust, and low noise telecommunications technology. Utilizing conventional chirped pulse amplification and subsequent nonlinear broadening in fiber yields a scalable few-cycle system, supporting watts of optical power, with MW peak powers, while still maintaining few-cycle pulses. Single pass χ(2) nonlinear interactions in a bulk crystal yields coverage from 350 to 22400 nm, with coherence being demonstrated at either end of the spectrum. This table top coherent infrared source provides higher power spectral densities than a synchrotron, opening new avenues for long-wave infrared spectroscopy and imaging. In the visible, the combination of instantaneous bandwidths exceeding 100 THz with inherent comb mode resolution offers new regimes of ro-vibronic spectroscopy. Finally, with focused intensities of this source exceeding TW/cm2, non-perturbative high harmonic generation can be explored in solid-state semiconductors. Utilizing the comb properties of the high power few-cycle source allows for ultra-sensitive measurements of the carrier envelope phase dependent UV spectra (from 200 - 650 nm) and opens new avenues for exploring sub-cycle dynamics in high field physics.</p
An Illustration of Inverse Probability Weighting to Estimate Policy-Relevant Causal Effects
Traditional epidemiologic approaches allow us to compare counterfactual outcomes under 2 exposure distributions, usually 100% exposed and 100% unexposed. However, to estimate the population health effect of a proposed intervention, one may wish to compare factual outcomes under the observed exposure distribution to counterfactual outcomes under the exposure distribution produced by an intervention. Here, we used inverse probability weights to compare the 5-year mortality risk under observed antiretroviral therapy treatment plans to the 5-year mortality risk that would had been observed under an intervention in which all patients initiated therapy immediately upon entry into care among patients positive for human immunodeficiency virus in the US Centers for AIDS Research Network of Integrated Clinical Systems multisite cohort study between 1998 and 2013. Therapy-naïve patients (n = 14,700) were followed from entry into care until death, loss to follow-up, or censoring at 5 years or on December 31, 2013. The 5-year cumulative incidence of mortality was 11.65% under observed treatment plans and 10.10% under the intervention, yielding a risk difference of −1.57% (95% confidence interval: −3.08, −0.06). Comparing outcomes under the intervention with outcomes under observed treatment plans provides meaningful information about the potential consequences of new US guidelines to treat all patients with human immunodeficiency virus regardless of CD4 cell count under actual clinical conditions
The effect of antiretroviral therapy on all-cause mortality, generalized to persons diagnosed with HIV in the USA, 2009–11
Background: Although antiretroviral therapy (ART) is known to be protective against HIV-related mortality, the expected magnitude of effect is unclear because existing estimates of the effect of ART may not directly generalize to recently HIV-diagnosed persons
Clinical Practice Recommendations on Genetic Testing of CYP2C9 and VKORC1 Variants in Warfarin Therapy
Objective: To systematically review evidence on genetic variants influencing outcomes during warfarin therapy and provide practice recommendations addressing the key questions: (1) Should genetic testing be performed in patients with an indication for warfarin therapy to improve achievement of stable anticoagulation and reduce adverse effects? (2) Are there subgroups of patients who may benefit more from genetic testing compared with others? (3) How should patients with an indication for warfarin therapy be managed based on their genetic test results? Methods: A systematic literature search was performed for VKORC1 and CYP2C9 and their association with warfarin therapy. Evidence was critically appraised, and clinical practice recommendations were developed based on expert group consensus. Results: Testing of VKORC1 (-1639G\u3eA), CYP2C92, and CYP2C93 should be considered for all patients, including pediatric patients, within the first 2 weeks of therapy or after a bleeding event. Testing for CYP2C95, 6, 8, or 11 and CYP4F2 (V433M) is currently not recommended. Testing should also be considered for all patients who are at increased risk of bleeding complications, who consistently show out-of-range international normalized ratios, or suffer adverse events while receiving warfarin. Genotyping results should be interpreted using a pharmacogenetic dosing algorithm to estimate the required dose. Significance: This review provides the latest update on genetic markers for warfarin therapy, clinical practice recommendations as a basis for informed decision making regarding the use of genotype-guided dosing in patients with an indication for warfarin therapy, and identifies knowledge gaps to guide future research.
Evaluation of a multidisciplinary lipid clinic to improve the care of individuals with severe lipid conditions: A RE-AIM framework analysis
BACKGROUND: Individuals with complex dyslipidemia, or those with medication intolerance, are often difficult to manage in primary care. They require the additional attention, expertise, and adherence counseling that occurs in multidisciplinary lipid clinics (MDLCs). We conducted a program evaluation of the first year of a newly implemented MDLC utilizing the RE-AIM (reach, effectiveness, adoption, implementation, and maintenance) framework to provide empirical data not only on program effectiveness, but also on components important to local sustainability and future generalizability.
METHODS: The purpose of the MDLC is to increase the uptake of guideline-based care for lipid conditions. Established in 2019, the MDLC provides care via a centralized clinic location within the healthcare system. Primary care providers and cardiologists were invited to refer individuals with lipid conditions. Using a pre/post-study design, we evaluated the implementation outcomes from the MDLC using the RE-AIM framework.
RESULTS: In 2019, 420 referrals were made to the MDLC (reach). Referrals were made by 19% (148) of the 796 active cardiology and primary care providers, with an average of 35 patient referrals per month in 2019 (SD 12) (adoption). The MDLC saw 83 patients in 2019 (reach). Additionally, 50% (41/82) had at least one follow-up MDLC visit, and 12% (10/82) had two or more follow-up visits in 2019 (implementation). In patients seen by the MDLC, we found an improved diagnosis of specific lipid conditions (FH (familial hypercholesterolemia), hypertriglyceridemia, and dyslipidemia), increased prescribing of evidence-based therapies, high rates of medication prior authorization approvals, and significant reductions in lipid levels by lipid condition subgroup (effectiveness). Over time, the operations team decided to transition from in-person follow-up to telehealth appointments to increase capacity and sustain the clinic (maintenance).
CONCLUSIONS: Despite limited reach and adoption of the MDLC, we found a large intervention effect that included improved diagnosis, increased prescribing of guideline-recommended treatments, and clinically significant reduction of lipid levels. Attention to factors including solutions to decrease the large burden of unseen referrals, discussion of the appropriate number and duration of visits, and sustainability of the clinic model could aid in enhancing the success of the MDLC and improving outcomes for more patients throughout the system
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