Experimental and numerical analysis of heat transfer and fluid flow characteristics inside pulsating heat pipe

Heat pipes are a popular choice for many industries and research applications to extract heat effectively by maintaining desired device/location at almost isothermal conditions. Pulsating heat pipes, also known as wickless heat pipes, transfers the heat mainly by pumping phenomenon caused by the phase change which set the pulsating vapor-fluid motion. The evaluation of fluid flow and heat transfer characteristics inside the pulsating heat pipe is complex and challenging due to the oscillating two-phase flow between the heat source and heat sink sections. In this paper, a numerical investigation of the closed-loop pulsating heat pipe is performed to study the fluid flow dynamics and evaluate its thermal characteristics. The volume of fluid method is employed to numerically simulate the two-phase unsteady incompressible flow inside the pulsating heat pipe. The heat pipe tube has a 2 mm inside diameter filled with methanol as a working fluid at a preset pressure. The thermal performance of pulsating heat pipe is evaluated for various heat pipe filling ratios (50%, 65%, and 75%) where heat input loads of 5 ? 15 W are supplied at the evaporator end for each filling ratio case. The thermal characteristics of the pulsating heat pipe are presented in terms of the thermal resistance, heat transfer coefficient, and effective thermal conductivity, whereas fluid flow dynamics are presented as flow patterns produced inside pulsating heat pipe. The numerical simulations are compared and validated with experimental results. From the present numerical and experimental study, a filling ratio of 65% is an optimized charge quality for the current configuration of the pulsating heat pipe.Scopu

Age-related incidence and outcomes of sepsis in California, 2008-2015.

PurposeSepsis remains amongst the most common causes of death worldwide. It has been described as a disease of the elderly, but contemporary data on risk factors and mortality is lacking.Materials and methodsMulti-center longitudinal cohort study using non-public, state of California data from January 1, 2008 to September 31, 2015. Patients with sepsis, severe sepsis, and septic shock were identified using ICD-9-CM diagnosis and procedure codes with age subgroups of 18-44, 45-64, 65-74, 75-84, and >85 years old. Descriptive statistics and a single direct logistic regression model were used to present data on incidence and mortality and to identify independent factors associated with mortality.ResultsOf 30,282,159 total inpatient encounters, 20,358,569 met inclusion criteria and 1,566,306 met sepsis criteria. Conditions associated with mortality included metastatic cancer, age, liver disease, residing in a care facility, and a gastrointestinal source of infection as well as fungal infection. Mortality in the >85-year-old subgroup with septic shock was 45.7%, lower than previously reported.ConclusionAge remains an important sepsis risk factor, but other conditions correlated more closely with sepsis-associated death. Patients over 85 years of age suffering from septic shock may have a better chance of survival than previously thought

RAMIC: Design of a randomized, double-blind, placebo-controlled trial to evaluate the efficacy of ramipril in patients with COVID-19.

Background and aimsRetrospective studies have shown that angiotensin-converting-enzyme (ACE) inhibitors are associated with a reduced risk of complications and mortality in persons with novel coronavirus disease 2019 (COVID-19). Thus, we aimed to examine the efficacy of ramipril, an ACE-inhibitor, in preventing ICU admission, mechanical ventilation and/or mortality while also minimizing the risk of transmission and use of personal protective equipment (PPE).MethodsRAMIC is a multicenter, randomized, double-blind, allocation-concealed, placebo-controlled trial comparing the efficacy of treatment with ramipril 2.5 mg orally daily compared to placebo for 14 days. The study population includes adult patients with COVID-19 who were admitted to a hospital or assessed in an emergency department or ambulatory clinic. Key exclusion criteria include ICU admission or need for mechanical ventilation at screening, use of an ACE inhibitor or angiotensin-receptor-II blocker within 7 days, glomerular filtration rate < 40 mL/min or a systolic blood pressure (BP) < 100 mmHg or diastolic BP < 65 mmHg. Patients are randomized 2:1 to receive ramipril (2.5 mg) or placebo daily. Informed consent and study visits occur virtually to minimize the risk of SARS-CoV-2 transmission and preserve PPE. The primary composite endpoint of ICU admission, invasive mechanical ventilation and death are adjudicated virtually.ConclusionsRAMIC is designed to assess the efficacy of treatment with ramipril for 14 days to decrease ICU admission, mechanical ventilator use and mortality in patients with COVID-19 and leverages virtual study visits and endpoint adjudication to mitigate risk of infection and to preserve PPE (ClinicalTrials.gov, NCT04366050)

RAMIC: Design of a randomized, double-blind, placebo-controlled trial to evaluate the efficacy of ramipril in patients with COVID-19.

Background and aimsRetrospective studies have shown that angiotensin-converting-enzyme (ACE) inhibitors are associated with a reduced risk of complications and mortality in persons with novel coronavirus disease 2019 (COVID-19). Thus, we aimed to examine the efficacy of ramipril, an ACE-inhibitor, in preventing ICU admission, mechanical ventilation and/or mortality while also minimizing the risk of transmission and use of personal protective equipment (PPE).MethodsRAMIC is a multicenter, randomized, double-blind, allocation-concealed, placebo-controlled trial comparing the efficacy of treatment with ramipril 2.5 mg orally daily compared to placebo for 14 days. The study population includes adult patients with COVID-19 who were admitted to a hospital or assessed in an emergency department or ambulatory clinic. Key exclusion criteria include ICU admission or need for mechanical ventilation at screening, use of an ACE inhibitor or angiotensin-receptor-II blocker within 7 days, glomerular filtration rate < 40 mL/min or a systolic blood pressure (BP) < 100 mmHg or diastolic BP < 65 mmHg. Patients are randomized 2:1 to receive ramipril (2.5 mg) or placebo daily. Informed consent and study visits occur virtually to minimize the risk of SARS-CoV-2 transmission and preserve PPE. The primary composite endpoint of ICU admission, invasive mechanical ventilation and death are adjudicated virtually.ConclusionsRAMIC is designed to assess the efficacy of treatment with ramipril for 14 days to decrease ICU admission, mechanical ventilator use and mortality in patients with COVID-19 and leverages virtual study visits and endpoint adjudication to mitigate risk of infection and to preserve PPE (ClinicalTrials.gov, NCT04366050)

Ramipril for the Treatment of COVID-19: RAMIC, a Randomized, Double-Blind, Placebo-Controlled Clinical Trial

IntroductionRetrospective studies report that angiotensin-converting enzyme inhibitors (ACEIs) may reduce the severity of COVID-19, but prospective data on de novo treatment with ACEIs are limited. The RAMIC trial was a randomized, multicenter, placebo-controlled, double-blind, allocation-concealed clinical trial to examine the efficacy of de novo ramipril versus placebo for the treatment of COVID-19.MethodsEligible participants were aged 18 years and older with a confirmed diagnosis of SARS-CoV-2 infection, recruited from urgent care clinics, emergency departments, and hospital inpatient wards at eight sites in the USA. Participants were randomly assigned to daily ramipril 2.5 mg or placebo orally in a 2:1 ratio, using permuted block randomization. Analyses were conducted on an intention-to-treat basis. The primary outcome was a composite of mortality, intensive care unit (ICU) admission, or invasive mechanical ventilation by day 14.ResultsBetween 27 May 2020 and 19 April 2021, a total of 114 participants (51% female) were randomized to ramipril (n = 79) or placebo (n = 35). The overall mean (± SD) age and BMI were 45 (± 15) years and 33 (± 8) kg/m2. Two participants in the ramipril group required ICU admission and one died, compared with none in the placebo group. There were no significant differences between ramipril and placebo in the primary endpoint (ICU admission, mechanical ventilation, or death) (3% versus 0%, p = 1.00) or adverse events (27% versus 29%, p = 0.82). The study was terminated early because of a low event rate and subsequent Emergency Use Authorization of therapies for COVID-19.ConclusionDe novo ramipril was not different compared with placebo in improving or worsening clinical outcomes from COVID-19 but appeared safe in non-critically ill patients with COVID-19.Trial registrationClinicaltrials.gov NCT04366050