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This study investigates the potential of a perforated structure for the control of near-wall turbulence in turbulent boundary layers. The perforated structure consists of a perforated plate, underneath of which is a backing chamber. The near-wall turbulent structures were analyzed using hot-wire measurements. Different inner-scaled chamber volumes from V + = 2.4 × 10 6 to 11.5 × 10 6 were considered to manipulate turbulent boundary layers at two Reynolds numbers of R e θ = 1165 and 2294. The findings reveal significant effects of the perforated structure on near-wall turbulent structures. Statistical analysis utilizing a variable-interval time-averaging technique illustrated a reduction of up to about 9% in sweep and ejection intensity, a decrease in about 25% in ejection frequency, and a decrease in approximately 33.5% in sweep frequency within the near-wall region, y + ≤ 30 , indicating that the perforated structure weakened burst events in this region. In addition, the perforated structure lifted the turbulence energy further from the wall. Consequently, there was a reduction of up to approximately 9% in turbulence intensities near the wall, contributing to locally diminished shear stresses and skin friction drag. When the inner-scaled chamber volume increased, the reduction in near-wall turbulence became more pronounced. [ABSTRACT FROM AUTHOR]

Igor Z Barjaktarevic,1 Russell G Buhr,1,2 Xiaoyan Wang,3 Scott Hu,1 David Couper,4 Wayne Anderson,4 Richard E Kanner,5 Robert Paine III,5 Surya P Bhatt,6 Nirav R Bhakta,7 Mehrdad Arjomandi,7 Robert J Kaner,8 Cheryl S Pirozzi,5 Jeffrey L Curtis,9,10 Wanda K O’Neal,4 Prescott G Woodruff,7 MeiLan K Han,9 Fernando J Martinez,8 Nadia Hansel,11 James Michael Wells,6 Victor E Ortega,12 Eric A Hoffman,13 Claire M Doerschuk,4 Victor Kim,14 Mark T Dransfield,6 M Bradley Drummond,4 Russell Bowler,15 Gerard Criner,14 Stephanie A Christenson,7 Bonnie Ronish,5 Stephen P Peters,12 Jerry A Krishnan,16 Donald P Tashkin,1 Christopher B Cooper1 On behalf of the NHLBI SubPopulations and InteRmediate Outcome Measures In COPD Study (SPIROMICS)1Department of Medicine, University of California, Los Angeles, Los Angeles, CA, USA; 2Department of Health Policy and Management, Fielding School of Public Health, University of California, Los Angeles, Los Angeles, CA, USA; 3Department of General Internal Medicine and Health Services Research, University of California, Los Angeles, Los Angeles, CA, USA; 4Department of Medicine, University of North Carolina, Chapel Hill, NC, USA; 5Department of Medicine, University of Utah, Salt Lake City, UT, USA; 6Division of Pulmonary, Allergy and Critical Care Medicine, University of Alabama at Birmingham, Birmingham, AL, USA; 7Department of Medicine, University of California, San Francisco, San Francisco, CA, USA; 8Department of Medicine, Weill Cornell Weill Cornell Medical Center, New York, NY, USA; 9Department of Medicine, University of Michigan, Ann Arbor, MI, USA; 10Medicine Service, VA Ann Arbor Healthcare System, Ann Arbor, MI, USA; 11Department of Medicine, John Hopkins University, Baltimore, MD, USA; 12Department of Medicine, Wake Forest School of Medicine, Winston-Salem, NC, USA; 13Department of Medicine, University of Iowa, Iowa City, IA, USA; 14Department of Thoracic Medicine and Surgery, Lewis Katz School of Medicine at Temple University, Philadelphia, PA, USA; 15Department of Medicine, National Jewish Health Systems, Denver, CO, USA; 16Department of Medicine, University of Illinois at Chicago, Chicago, IL, USACorrespondence: Christopher B CooperDepartments of Medicine and Physiology, David Geffen School of Medicine, University of California Los Angeles, 10833 Le Conte Avenue, 37-131 CHS, Los Angeles, CA 90095, USAEmail ccooper@mednet.ucla.eduObjective: Bronchodilator responsiveness (BDR) is prevalent in COPD, but its clinical implications remain unclear. We explored the significance of BDR, defined by post-bronchodilator change in FEV1 (BDRFEV1) as a measure reflecting the change in flow and in FVC (BDRFVC) reflecting the change in volume.Methods: We analyzed 2974 participants from a multicenter observational study designed to identify varying COPD phenotypes (SPIROMICS). We evaluated the association of BDR with baseline clinical characteristics, rate of prospective exacerbations and mortality using negative binomial regression and Cox proportional hazards models.Results: A majority of COPD participants exhibited BDR (52.7%). BDRFEV1 occurred more often in earlier stages of COPD, while BDRFVC occurred more frequently in more advanced disease. When defined by increases in either FEV1 or FVC, BDR was associated with a self-reported history of asthma, but not with blood eosinophil counts. BDRFVC was more prevalent in subjects with greater emphysema and small airway disease on CT. In a univariate analysis, BDRFVC was associated with increased exacerbations and mortality, although no significance was found in a model adjusted for post-bronchodilator FEV1.Conclusion: With advanced airflow obstruction in COPD, BDRFVC is more prevalent in comparison to BDRFEV1 and correlates with the extent of emphysema and degree of small airway disease. Since these associations appear to be related to the impairment of FEV1, BDRFVC itself does not define a distinct phenotype nor can it be more predictive of outcomes, but it can offer additional insights into the pathophysiologic mechanism in advanced COPD.Clinical trials registration: ClinicalTrials.gov: NCT01969344T4.Keywords: bronchodilator responsiveness, inspiratory capacity, FVC, FEV1, SPIROMICS

Barjaktarevic IZ, Buhr RG, Wang X, et al. Int J Chron Obstruct Pulmon Dis. 2019;14:2927– 2938. The authors have advised that there is an error in the Funding section on page 2935. The correct funding statement is as follows: FundingThis study was supported by R01HL125432-01A1 (MBD), T32HL007106-41 (RMB), and TL1TR001883-01 (RGB). SPIROMICS was supported by contracts from the NIH/NHLBI (HHSN268200900013C, HHSN2682009 00014C, HHSN268200900015C, HHSN268200900016C, HHSN268200900017C, HHSN268200900018C, HHSN268200 900019C, and HHSN268200900020C) and supplemented by contributions made through the Foundation for the NIH and the COPD Foundation from AstraZeneca/MedImmune, Bayer, Bellerophon Therapeutics, Boehringer-Ingelheim Pharmaceuticals, Inc., Chiesi Farmaceutici S.p.A., Forest Research Institute, Inc., GlaxoSmithKline, Grifols Therapeutics, Inc., Ikaria, Inc., Nycomed GmbH, Takeda Pharmaceutical Company, Novartis Pharmaceuticals Corporation, ProterixBio; Regeneron Pharmaceuticals, Inc., Sanofi, and Sunovion. The PRM analyses were supported by NHLBI HL122438 and HL138188. Mehrdad Arjomandi was supported by a grant from the Flight Attendant Medical Research Institute. The authors apologize for this error. Read the original article

Introduction: Oral intake of vitamins which present antioxidant characteristics can protect living organisms against oxidative damage caused by exposure to ionizing radiation. It was previously reported that administration of high levels of vitamin C can lead to increased DNA damage through production of hydroxyl radicals from hydrogen peroxide by the Fenton reaction. However, our early experiments did not confirm this hypothesis. The main goal of this study was to determine if high doses of Vit C can show life-saving radioprotective effects. Materials and Methods: Phase I: Seventy two male Balb/c mice weighing 20-25g were randomly divided into six groups of 12 animals each. Group I; Vit E for five days, Groups II and III; Vit C and Vit A. Group 4; all three vitamins. Group V; an over-the-counter multivitamin. Group VI; none of the above. Phase II: 120 male BALB/c mice weighing 20-25g were randomly divided into 12 groups of 10 each. Group I; Vit A for five days. Groups II-IV; Vit C 200 mg/kg, 400 mg/kg, 800 mg/kg, respectively. Group V-VII; Vit E at daily doses of 200 iu/kg, 400 iu/kg, 800 iu/kg, respectively. Group VIII and IX; all three vitamins at low and high doses, respectively. Group X; an over-the-counter multivitamin. Group XI; controls group and Group XII; received pure olive oil. All animals (Phases I and II) were exposed to a lethal dose of gamma rays and the survival rates of the animals were monitored and recorded continuously for 16 days after exposure. Results: Phase I: 14 days after irradiation the survival rate for control group was 33.33%, while the survival rates for the 1st to 5th groups were 45.45%, 81.81%, 50%, 57.14%, and 9.09% , respectively. Phase II: The survival rates in the control group and the group that only received pure olive oil, were 50% and 60%, respectively. Survival rate in the animals received Vit C at daily doses of 200 mg/kg, 400 mg/kg, 800 mg/kg, were 90%, 90% and 90%, respectively. Log rank (Mantel-Cox) test showed statistically significant differences between the survival rates in control irradiated mice (no vitamins) and mice received Vit C at daily doses of 200 mg/kg (P=0.042), 400 mg/kg (P=0.042) and 800 mg/kg (P=0.042). Conclusion: Altogether, findings of this study showed that even high doses of Vit C can show life-saving radioprotective effects. The significant radioprotective effect of Vit C at doses used in this study, opens new horizons in developing non-toxic, cost effective, easily available radioprotectors in life-threatening situations such as exposure to lethal doses of ionizing radiation. The radioprotective effect of Vit A and Vit E seem to be less efficient compared to that of Vit C.