Impact of plasma jet geometry on residence times of radical species

Numerous electrode geometries and power supplies, both commercial and in-house, have been employed for the generation of low-temperature atmospheric plasma jets. In this work, the development and operation of a 12 jet nonthermal atmospheric plasma system is presented. The study is based on optical spectroscopy as a diagnostic method due to its nonintrusive nature. A key focus of this study was the material selection (conductive and nonconductive), with several polymers screened for the jet design leading to polyacetal as the choice material. Their results are compared with other atmospheric plasma jet systems. The results show a significant increase in residence time and the spatial homogeneity for ambient air's main species, including: OH, O I, O2, O3, N2, and N2+. Their densities are studied with respect to treatment time, distance, duty cycle, and discharge frequency, as well as the jets' carrier gas chemistries (argon and helium). For their plasma jet system, the bulk of the chemical reactions occur in the surrounding atmosphere and not in the jet nozzle, which is different from most other plasma jet systems. The electron energy distribution function, for the given chemistries, is also reporte

Impact of atmospheric pressure nonequilibrium plasma discharge on polymer surface metrology

Due to the attraction of plasma technologies as a clean and efficient means of surface modification, significant research has gone into the physical and chemical aspects of polymer functionalization. In this study, it was shown that the use of an atmospheric plasma jet can efficiently modify the surface of polyethylene terephthalate samples and change their hydrophobic properties to more hydrophilic characteristics. The dependence on the changes with respect to time, distance, and atomic oxygen (O I) intensity were considered as factors. It was found that with closer proximity to the plasma source (without causing thermal degradation) and with increasing levels of O I, that the changes of water contact angle and surface free energy can be maximized. It was also observed that the electron energy distribution function, for a given chemistry, significantly differed with changes in distance from the jet nozzle. This shows that for this type of plasma jet system, the bulk of the chemical reactions occur in the nozzle of the jet and not in the surrounding atmosphere. Therefore, this leads to more efficient energy transfer, higher gas temperatures, and better surface activation of samples when compared to systems that produce external chemical reactions due to more diffusion in the surrounding atmosphere and loss of reactive species to other atoms and molecules that are present

Spectroscopic study of excited molecular nitrogen generation due to interactions of metastable noble gas atoms

This work provides an insight into the generation of excited nitrogen species by allowing noble gases to interact both with one another and ambient air. He and Ar were utilized to generate the optimum selectivity process to create reactive nitrogen species. An optimum setting for the generation of excited molecular nitrogen species, based on their excited energy levels, was obtained when using a mixture of Ar-He at a ratio of 10:1. At that point, when a voltage of 27 kV is applied to the system, it reached the maximum efficiency for selectivity processes to occur which allowed for a greater non-radiative transfer of energy through the mixture of noble gas atoms and into the molecular nitrogen present in ambient air

Parental Attitudes to Myopia: a Key Agent of Change for Myopia Control?

Purpose With the increasing prevalence in myopia there is growing interest in active myopia prevention. This study aims to increase our understanding of parental attitudes to myopia development and control, as a means to inform future health planning and policy. It evaluates, for the first time, the attitude of parents to myopia and its associated risks, as well as assessing the exposure of Irish children to environmental factors that may influence their risk profile for myopia development. Methods Parents of 8–13 year old children in eight participating schools completed a questionnaire designed to assess their knowledge of and attitudes towards myopia and its risk factors. A structured diary was also used to capture daily activities of children in relation to myopia risk factors. Results Of 329 parents, just 46% considered that myopia presented a health risk to their children, while an identical number (46%) regarded it as an optical inconvenience. Myopia was also, but less frequently, considered an expense (31% of parents), a cosmetic inconvenience (14% of parents) and, by some, as a sign of intelligence (4% of parents) 76% of parents recognised the potential of digital technology to impact the eye, particularly as a cause of eyestrain and need for spectacles. Only 14% of parents expressed concern should their child be diagnosed with myopia. Compared to non myopic parents, myopic parents viewed myopia as more of an optical inconvenience (p \u3c 0.001), an expense (p \u3c 0.005) and a cosmetic inconvenience (p \u3c 0.001). There was a trend for myopic parents to limit screen time use in their household more than non‐myopic parents (p = 0.05). Parents who considered myopia a health risk sought to limit screen time more than parents who did not regard myopia as a health risk to their child (p = 0.01). Children spent significantly longer performing indoor proximal tasks (255 min) compared to time spent outdoors (180 min; p \u3c 0.0001) daily. Older (p = 0.001), urban (p = 0.0005) myopic (=0.04) children spent significantly more time at digital screens compared to younger non‐myopic children from a rural background. Conclusion Parental attitudes to myopia were typically nonchalant in relation to health risk. This is of particular concern given the impact parents have on children\u27s behaviour and choices with respect to such risk factors, demonstrating an acute need for societal sensitisation to the public health importance of myopia

Screening of Exosomal MicroRNAs From Colorectal Cancer Cells

BACKGROUND: Cells release extracellular membrane vesicles including microvesicles known as exosomes. Exosomes contain microRNAs (miRNAs) however the full range within colorectal cancer cell secreted exosomes is unknown. OBJECTIVE: To identify the full range of exosome encapsulated miRNAs secreted from 2 colorectal cancer cell lines and to investigate engineering of exosomes over-expressing miRNAs. METHODS: Exosomes were isolated from HCT-116 and HT-29 cell lines. RNA was extracted from exosomes and microRNA array performed. Cells were engineered to express miR-379 (HCT-116-379) or a non-targeting control (HCT-116-NTC) and functional effects were determined. Exosomes secreted by engineered cells were transferred to recipient cells and the impact examined. RESULTS: Microvesicles 40-100 nm in size secreted by cell lines were visualised and confirmed to express exosomal protein CD63. HT-29 exosomes contained 409 miRNAs, HCT-116 exosomes contained 393, and 338 were common to exosomes from both cell lines. Selected targets were validated. HCT-116-379 cells showed decreased proliferation (12-15% decrease, p \u3c 0.001) and decreased migration (32-86% decrease, p \u3c 0.001) compared to controls. HCT-116-379 exosomes were enriched for miR-379. Confocal microscopy visualised transfer of HCT-116-379 exosomes to recipient cells. CONCLUSIONS: Colorectal cancer cells secrete a large number of miRNAs within exosomes. miR-379 decreases cell proliferation and migration, and miR-379 enriched exosomes can be engineered

A population of proinflammatory T cells coexpresses αβ and γδ T cell receptors in mice and humans

T cells are classically recognized as distinct subsets that express αβ or γδ TCRs. We identify a novel population of T cells that coexpress αβ and γδ TCRs in mice and humans. These hybrid αβ-γδ T cells arose in the murine fetal thymus by day 16 of ontogeny, underwent αβ TCR–mediated positive selection into CD4+ or CD8+ thymocytes, and constituted up to 10% of TCRδ+ cells in lymphoid organs. They expressed high levels of IL-1R1 and IL-23R and secreted IFN-γ, IL-17, and GM-CSF in response to canonically restricted peptide antigens or stimulation with IL-1β and IL-23. Hybrid αβ-γδ T cells were transcriptomically distinct from conventional γδ T cells and displayed a hyperinflammatory phenotype enriched for chemokine receptors and homing molecules that facilitate migration to sites of inflammation. These proinflammatory T cells promoted bacterial clearance after infection with Staphylococcus aureus and, by licensing encephalitogenic Th17 cells, played a key role in the development of autoimmune disease in the central nervous system

Trends in, and factors associated with, HIV infection amongst tuberculosis patients in the era of anti-retroviral therapy: a retrospective study in England, Wales and Northern Ireland

Background: HIV increases the progression of latent tuberculosis (TB) infection to active disease and contributed to increased TB in the UK until 2004. We describe temporal trends in HIV infection amongst patients with TB and identify factors associated with HIV infection. / Methods: We used national surveillance data of all TB cases reported in England, Wales and Northern Ireland from 2000 to 2014 and determined HIV status through record linkage to national HIV surveillance. We used logistic regression to identify associations between HIV and demographic, clinical and social factors. / Results: There were 106,829 cases of TB in adults (≥ 15 years) reported from 2000 to 2014. The number and proportion of TB patients infected with HIV decreased from 543/6782 (8.0%) in 2004 to 205/6461 (3.2%) in 2014. The proportion of patients diagnosed with HIV > 91 days prior to their TB diagnosis increased from 33.5% in 2000 to 60.2% in 2013. HIV infection was highest in people of black African ethnicity from countries with high HIV prevalence (32.3%), patients who misused drugs (8.1%) and patients with miliary or meningeal TB (17.2%). / Conclusions: There has been an overall decrease in TB-HIV co-infection and a decline in the proportion of patients diagnosed simultaneously with both infections. However, high rates of HIV remain in some sub-populations of patients with TB, particularly black Africans born in countries with high HIV prevalence and people with a history of drug misuse. Whilst the current policy of testing all patients diagnosed with TB for HIV infection is important in ensuring appropriate management of TB patients, many of these TB cases would be preventable if HIV could be diagnosed before TB develops. Improving screening for both latent TB and HIV and ensuring early treatment of HIV in these populations could help prevent these TB cases. British HIV Association guidelines on latent TB testing for people with HIV from sub-Saharan Africa remain relevant, and latent TB screening for people with HIV with a history of drug misuse, homelessness or imprisonment should also be considered

Th1 type lymphocyte reactivity to metals in patients with total hip arthroplasty

<p>Abstract</p> <p>Background</p> <p>All prostheses with metallic components release metal debris that can potentially activate the immune system. However, implant-related metal hyper-reactivity has not been well characterized. In this study, we hypothesized that adaptive immunity reaction(s), particularly T-helper type 1 (Th1) responses, will be dominant in any metal-reactivity responses of patients with total joint replacements (TJAs). We tested this hypothesis by evaluating lymphocyte reactivity to metal "ions" in subjects with and without total hip replacements, using proliferation assays and cytokine analysis.</p> <p>Methods</p> <p>Lymphocytes from young healthy individuals without an implant or a history of metal allergy (Group 1: n = 8) were used to assess lymphocyte responses to metal challenge agents. In addition, individuals (Group 2: n = 15) with well functioning total hip arthroplasties (average Harris Hip Score = 91, average time in-situ 158 months) were studied. Age matched controls with no implants were also used for comparison (Group 3, n = 8, 4 male, 4 female average age 70, range 49–80). Group 1 subjects' lymphocyte proliferation response to Aluminum⁺³, Cobalt⁺², Chromium⁺³, Copper⁺², Iron⁺³, Molybdenum⁺⁵, Manganeese⁺², Nickel⁺², Vanadium⁺³and Sodium⁺²chloride solutions at a variety of concentrations (0.0, 0.05, 0.1, 0.5, 1.0 and 10.0 mM) was studied to establish toxicity thresholds. Mononuclear cells from Group 2 and 3 subjects were challenged with 0.1 mM CrCl₃, 0.1 mM NiCl₂, 0.1 mM CoCl₂and approx. 0.001 mM titanium and the reactions measured with proliferation assays and cytokine analysis to determine T-cell subtype prominence.</p> <p>Results</p> <p>Primary lymphocytes from patients with well functioning total hip replacements demonstrated a higher incidence and greater magnitude of reactivity to chromium than young healthy controls (p < 0.03). Of the 15 metal ion-challenged subjects with well functioning total hip arthroplasties, 7 demonstrated a proliferative response to Chromium, Nickel, Cobalt and/or Titanium (as defined by a statistically significant >2 fold stimulation index response, p < 0.05) and were designated as metal-reactive. Metals such as Cobalt, Copper, Manganese, and Vanadium were toxic at concentrations as low as 0.5 mM while other metals, such as Aluminum, Chromium, Iron, Molybdenum, and Nickel, became toxic at much higher concentrations (>10 mM). The differential secretion of signature T-cell subsets' cytokines (Th1 and Th2 lymphocytes releasing IFN-gamma and IL-4, respectively) between those total hip arthroplasty subjects which demonstrated metal-reactivity and those that did not, indicated a Th1 type (IFN-gamma) pro-inflammatory response.</p> <p>Conclusion</p> <p>Elevated proliferation and production of IFN-gamma to metals in hip arthroplasty subjects' lymphocytes indicates that a Th1 (vs. Th2) type response is likely associated with any metal induced reactivity. The involvement of an elevated and specific lymphocyte response suggests an <it>adaptive </it>(macrophage recruiting) immunity response to metallic implant debris rather than an <it>innate </it>(nonspecific) immune response.</p

Towards better guidance on caseload thresholds to promote positive tuberculosis treatment outcomes:a cohort study

BACKGROUND: In low-incidence countries, clinical experience of tuberculosis is becoming more limited, with potential consequences for patient outcomes. In 2007, the Department of Health released a guidance 'toolkit' recommending that tuberculosis patients in England should not be solely managed by clinicians who see fewer than 10 cases per year. This caseload threshold was established to try to improve treatment outcomes and reduce transmission, but was not evidence based. We aimed to assess the association between clinician or hospital caseload and treatment outcomes, as well as the relative suitability of making recommendations using each caseload parameter. METHODS: Demographic and clinical data for tuberculosis cases in England notified to Public Health England's Enhanced Tuberculosis Surveillance system between 2003 and 2012 were extracted. Mean clinician and hospital caseload over the past 3 years were calculated and treatment outcomes grouped into good/neutral and unfavourable. Caseloads over time and their relationship with outcomes were described and analysed using random effects logistic regression, adjusted for clustering. RESULTS: In a fully adjusted multivariable model (34,707 cases)there was very strong evidence that management of tuberculosis by clinicians with fewer than 10 cases per year was associated with greater odds of an unfavourable outcome compared to clinicians who managed greater numbers of cases (cluster-specific odds ratio, 1.14; 95 % confidence interval, 1.05-1.25; P = 0.002). The relationship between hospital caseload and treatment outcomes was more complex and modified by a patient's place of birth and ethnicity. The clinician caseload association held after adjustment for hospital caseload and when the clinician caseload threshold was reduced down to one. CONCLUSIONS: Despite the relative ease of making recommendations at the hospital level and the greater reliability of recorded hospital versus named clinician, our results suggest that clinician caseload thresholds are more suitable for clinical guidance. The current recommended clinician caseload threshold is functional. Sensitivity analyses reducing the threshold indicated that clinical experience is pertinent even at very low average caseloads, which is encouraging for low burden settings