Evaporation of Lennard-Jones Fluids

Evaporation and condensation at a liquid/vapor interface are ubiquitous interphase mass and energy transfer phenomena that are still not well understood. We have carried out large scale molecular dynamics simulations of Lennard-Jones (LJ) fluids composed of monomers, dimers, or trimers to investigate these processes with molecular detail. For LJ monomers in contact with a vacuum, the evaporation rate is found to be very high with significant evaporative cooling and an accompanying density gradient in the liquid domain near the liquid/vapor interface. Increasing the chain length to just dimers significantly reduces the evaporation rate. We confirm that mechanical equilibrium plays a key role in determining the evaporation rate and the density and temperature profiles across the liquid/vapor interface. The velocity distributions of evaporated molecules and the evaporation and condensation coefficients are measured and compared to the predictions of an existing model based on kinetic theory of gases. Our results indicate that for both monatomic and polyatomic molecules, the evaporation and condensation coefficients are equal when systems are not far from equilibrium and smaller than one, and decrease with increasing temperature. For the same reduced temperature $T/T_c$, where $T_c$ is the critical temperature, these two coefficients are higher for LJ dimers and trimers than for monomers, in contrast to the traditional viewpoint that they are close to unity for monatomic molecules and decrease for polyatomic molecules. Furthermore, data for the two coefficients collapse onto a master curve when plotted against a translational length ratio between the liquid and vapor phase.Comment: revised version, 15 pages, 15 figures, to appear in J. Chem. Phy

Оценка инвестиционной деятельности электроэнергетической компании

Объектом исследования является электроэнергетическая компания ПАО «ТРК». Предметом исследования выступают оценка эффективности инвестиций и инвестиционная деятельность предприятий электроэнергетики. Цель работы - анализ показателей оценки эффективности инвестиционной деятельности и разработка рекомендаций по совершенствованию оценки инвестиционной деятельности на примере компании ПАО «Томская распределительная компания».The object of this study is to electric power company PJSC "TRK". The subject of research are the evaluation of the effectiveness of investments and investment activity of the enterprises of electric power industry. Purpose - analysis of indicators for assessing the effectiveness of investment and development of recommendations to improve the assessment of investment activity on the example of the company PJSC "Tomsk Distribution Company"

Status of Superconducting RF Linac Development for APT

This paper describes the development progress of high current superconducting RF linacs in Los Alamos, performed to support a design of the linac for the APT (Accelerator Production of Tritium) Project. The APT linac design includes a CW superconducting RF high energy section, spanning an energy range of 211 to 1030 MeV, and operating at a frequency of 700 MHz with two constant beta sections (beta of 0.64 and 0.82). In the last two years, we have progressed towards build a cryomodule with beta of 0.64. We completed the designs of the 5 cell superconducting cavities and the 210 kW power couplers. We are scheduled to begin assembly of the cryomodule in September 2000. In this paper, we present an overview of the status of our development efforts and a report on the results of the cavity and coupler test program.Comment: LINAC2000 THD1

Sex differences in clinical characteristics and outcomes in patients undergoing heart transplantation

Aims: Whether sex affects selection for and outcomes after heart transplantation (HTx) remains unclear. We aimed to show sex differences in pre‐transplant characteristics and outcomes after HTx. Methods and results: From 1995 to 2019, 49 200 HTx recipients were prospectively enrolled in the Organ Procurement and Transplantation Network. Logistic regression models were used to evaluate clinical characteristics by sex. Multivariable Cox regression models were fitted to assess sex differences in all‐cause mortality, cardiovascular mortality, graft failure, cardiac allograft vasculopathy (CAV), and malignancy. In 49 200 patients (median age 55 years, interquartile range 46–62; 24.6% women), 49 732 events occurred during a median follow‐up of 8.1 years. Men were older than women, had more often ischaemic cardiomyopathy (odds ratio [OR] 3.26, 95% confidence interval [CI] 3.11–3.42; P < 0.001), and a higher burden of cardiovascular risk factors, whereas women had less malignancies (OR 0.47, CI 0.44–0.51; P < 0.001). Men were more often treated in intensive care unit (OR 1.24, CI 1.12–1.37; P < 0.001) with a higher need for ventilatory (OR 1.24, CI 1.17–1.32; P < 0.001) or VAD (OR 1.53, CI 1.45–1.63; P < 0.001) support. After multivariable adjustment, men had a higher risk for CAV (hazard ratio [HR] 1.21, CI 1.13–1.29; P < 0.001) and malignancy (HR 1.80, CI 1.62–2.00; P < 0.001). There were no differences in all‐cause mortality, cardiovascular mortality, and graft failure between sexes. Conclusions: In this US transplant registry, men and women differed in pre‐transplant characteristics. Male sex was independently associated with incident CAV and malignancy even after multivariable adjustment. Our results underline the need for better personalized post‐HTx management and care

Non-insulin antihyperglycaemic drugs and heart failure: an overview of current evidence from randomized controlled trials.

Type 2 diabetes mellitus (T2DM) is highly prevalent in the general population and especially in patients with heart failure (HF). It is not only a risk factor for incident HF, but is also associated with worse outcomes in prevalent HF. Therefore, antihyperglycaemic management in patients at risk of or with established HF is of importance to reduce morbidity/mortality. Following revision of the drug approval process in 2008 by the Food and Drug Administration and European Medicines Agency, several cardiovascular outcome trials on antihyperglycaemic drugs have recently investigated HF endpoints. Signals of harm in terms of increased risk of HF have been identified for thiazolidinediones and the dipeptidyl peptidase 4 inhibitor saxagliptin, and therefore, these drugs are not currently recommended in HF. Sulfonylureas also have an unfavourable safety profile and should be avoided in patients at increased risk of/with HF. Observational studies have assessed the use of metformin in patients with HF, showing potential safety and potential survival/morbidity benefits. Overall use of glucagon-like peptide 1 receptor agonists has not been linked with any clear benefit in terms of HF outcomes. Sodium-glucose cotransporter protein 2 inhibitors (SGLT2i) have consistently shown to reduce risk of HF-related outcomes in T2DM with and without HF and are thus currently recommended to lower risk of HF hospitalization in T2DM. Recent findings from the DAPA-HF trial support the use of dapagliflozin in patients with HF with reduced ejection fraction and, should ongoing trials with empagliflozin, sotagliflozin, and canagliflozin prove efficacy, will pave the way for SGLT2i as HF treatment regardless of T2DM

Empagliflozin in Heart Failure With Predicted Preserved Versus Reduced Ejection Fraction: Data From the EMPA-REG OUTCOME Trial

Background: In the EMPA-REG OUTCOME trial, ejection fraction (EF) data were not collected. In the subpopulation with heart failure (HF), we applied a new predictive model for EF to determine the effects of empagliflozin in HF with predicted reduced (HFrEF) vs preserved (HFpEF) EF vs no HF. / Methods and Results: We applied a validated EF predictive model based on patient baseline characteristics and treatments to categorize patients with HF as being likely to have HF with mid-range EF (HFmrEF)/HFrEF (EF <50%) or HFpEF (EF ≥50%). Cox regression was used to assess the effect of empagliflozin vs placebo on cardiovascular death/HF hospitalization (HHF), cardiovascular and all-cause mortality, and HHF in patients with predicted HFpEF, HFmrEF/HFrEF and no HF. Of 7001 EMPA-REG OUTCOME patients with data available for this analysis, 6314 (90%) had no history of HF. Of the 687 with history of HF, 479 (69.7%) were predicted to have HFmrEF/HFrEF and 208 (30.3%) to have HFpEF. Empagliflozin's treatment effect was consistent in predicted HFpEF, HFmrEF/HFrEF and no-HF for each outcome (HR [95% CI] for the primary outcome 0.60 [0.31–1.17], 0.79 [0.51–1.23], and 0.63 [0.50–0.78], respectively; P interaction = 0.62). / Conclusions: In EMPA-REG OUTCOME, one-third of the patients with HF had predicted HFpEF. The benefits of empagliflozin on HF and mortality outcomes were consistent in nonHF, predicted HFpEF and HFmrEF/HFrEF

Numerical investigation of nanoporous evaporation using direct simulation Monte Carlo

Evaporation is an effective cooling mechanism widely exploited in the thermal management of modern electronic devices, with a growing interest in the evaporation process in thin film based nanoporous membrane technologies. At such scales, classical approaches fail and one requires solutions of the Boltzmann equation; these are obtained here using the direct simulation Monte Carlo method. In particular, the evaporation from representative nanoporous meniscus shapes, corresponding to different operating conditions, has been investigated. Evaporation rates for the different conditions have been characterized as a function of a wide range of Knudsen numbers and free-stream Mach numbers. Additionally, the influence of porosity and evaporation coefficient on the nanoporous evaporation rates has been assessed. Investigations have also been carried out to consider cases where the meniscus has sunk within the pore, and cooling efficacy compared with cases where the meniscus is pinned to the top of the pore. This work demonstrates that the net evaporative mass flux is ultimately determined by the interplay between various physical effects, whose dominance is quantified by the Knudsen number, porosity, evaporation coefficient and the meniscus shape. This work thus provides useful information for the design of nanoporous membrane-based cooling devices