High-performance thermal emitters based on laser engineered metal surfaces

Effective thermal management is of paramount importance for all high-temperature systems operating under vacuum. Cooling of such systems relies mainly on radiative heat transfer requiring high spectral emissivity of surfaces, which is strongly affected by the surface condition. Pulsed laser structuring of stainless steel in air resulted in the spectral hemispherical emissivity values exceeding 0.95 in the 2.5–15 µm spectral region. The effects of surface oxidation and topography on spectral emissivity as well as high temperature stability of the surface structures were examined. High performance stability of the laser textured surfaces was confirmed after thermal aging studies at 320°C for 96 hour

Disappearing cosmological constant in f(R) gravity

For higher-derivative f(R) gravity where R is the Ricci scalar, a class of models is proposed which produce viable cosmology different from the LambdaCDM one at recent times and satisfy cosmological, Solar system and laboratory tests. These models have both flat and de Sitter space-times as particular solutions in the absence of matter. Thus, a cosmological constant is zero in flat space-time, but appears effectively in a curved one for sufficiently large R. A 'smoking gun' for these models would be small discrepancy in values of the slope of the primordial perturbation power spectrum determined from galaxy surveys and CMB fluctuations. On the other hand, a new problem for dark energy models based on f(R) gravity is pointed which is connected with possible overproduction of new massive scalar particles (scalarons) arising in this theory in the very early Universe.Comment: 8 pages, footnote clarified, grammatical typo corrected, references added, final version to be published in JETP

Characterization of the water diffusion in GEM foil material

Systematic studies on the GEM foil material are performed to measure the moisture diffusion rate and saturation level.These studies are important because the presence of this compound inside the detector’s foil can possibly change its mechanical and electrical properties,and in such a way,the detector performance can be affected.To understand this phenomenon,a model is developed with COMSOL Multiphysicsv.4.3 which described the adsorption and diffusion within the geometry of GEM foil,the concentration profiles and the time required to saturate the foil.The COMSOL model is verified by experimental observations on a GEM foil sample.This note will describe the model and its experimental verification results

Multi-omics comparison of malignant and normal uveal melanocytes reveals molecular features of uveal melanoma.

Uveal melanoma (UM) is a rare cancer resulting from the transformation of melanocytes in the uveal tract. Integrative analysis has identified four molecular and clinical subsets of UM. To improve our molecular understanding of UM, we performed extensive multi-omics characterization comparing two aggressive UM patient-derived xenograft models with normal choroidal melanocytes, including DNA optical mapping, specific histone modifications, and DNA topology analysis using Hi-C. Our gene expression and cytogenetic analyses suggest that genomic instability is a hallmark of UM. We also identified a recurrent deletion in the BAP1 promoter resulting in loss of expression and associated with high risk of metastases in UM patients. Hi-C revealed chromatin topology changes associated with the upregulation of PRAME, an independent prognostic biomarker in UM, and a potential therapeutic target. Our findings illustrate how multi-omics approaches can improve our understanding of tumorigenesis and reveal two distinct mechanisms of gene expression dysregulation in UM

A dimensioning and tolerancing methodology for concurrent engineering applications I: problem representation

This paper is the first of two which present a methodology for determining the dimensional specifications of all the component parts and sub-assemblies of a product according to their dimensional requirements. To achieve this goal, two major steps are followed, each of which is described in a paper. In the first paper, all relationships necessary for finding the values of dimensions and tolerances are represented in a matrix form, known as a Dimensional Requirements/Dimensions (DR/D) matrix. In the second paper, the values of individual dimensions and tolerances are determined by applying a comprehensive solution strategy to satisfy all the relationships represented in the DR/D matrix. The methodology is interactive and suitable for use in a concurrent engineering (CE) environment. The graphical tool presented in this paper will assist a CE team in visualizing the overall D&T problem and foreseeing the ramifications of decisions regarding the selection of dimensions and tolerances. This will assist the CE team to systematically determine all the controllable variables, such as dimensions, tolerances, and manufacturing processes

Microchannel cooling for the LHCb VELO Upgrade I

The LHCb VELO Upgrade I, currently being installed for the 2022 start of LHC Run 3, uses silicon microchannel coolers with internally circulating bi-phase \cotwo for thermal control of hybrid pixel modules operating in vacuum. This is the largest scale application of this technology to date. Production of the microchannel coolers was completed in July 2019 and the assembly into cooling structures was completed in September 2021. This paper describes the R\&D path supporting the microchannel production and assembly and the motivation for the design choices. The microchannel coolers have excellent thermal peformance, low and uniform mass, no thermal expansion mismatch with the ASICs and are radiation hard. The fluidic and thermal performance is presented.Comment: 31 pages, 27 figure

Impact of Epicatechin on the Procoagulant Activities of Microparticles

International audienceMicroparticles play a role in cardiovascular disease pathology. The flavanol-like epicatechin is increasingly considered due to its cardioprotective effects. The aim of this study was to investigate the impact of epicatechin on microparticle generation, phenotype and procoagulant properties. Plasma samples from 15 healthy subjects were incubated with increasing concentrations of epicatechin (1 to 100 mu M). Then, the expression of glycoprotein IIb, phosphatidylserine (PS), glycoprotein Ib (GPIb) and P-selectin was assessed by flow cytometry analysis after (or not) platelet stimulation. Microparticle procoagulant activity was determined using Zymuphen MP and Zymuphen (TM) MP-TF for phospholipid and tissue factor content, and with thrombin generation (TG) assays for procoagulant function. Platelet microparticles that express GPIb (/mu L) decreased from 20,743 +/- 24,985 (vehicle) to 14,939 +/- 14,333 (p = 0.6), 21,366 +/- 16,949 (p = 0.9) and 15,425 +/- 9953 (p < 0.05) in samples incubated with 1, 10 and 100 mu M epicatechin, respectively. Microparticle concentration (nM PS) decreased from 5.6 +/- 2.0 (vehicle) to 5.1 +/- 2.2 (p = 0.5), 4.5 +/- 1.5 (p < 0.05) and 4.7 +/- 2.0 (p < 0.05) in samples incubated with 1, 10 and 100 mu M epicatechin, respectively. Epicatechin had no impact on tissue factor-positive microparticle concentration. Epicatechin decreased TG (endogenous thrombin potential, nM.min) from 586 +/- 302 to 509 +/- 226 (p = 0.3), 512 +/- 270 (p = 0.3) and 445 +/- 283 (p < 0.05). These findings indicate that epicatechin affects microparticle release, phenotype and procoagulant properties

Tolerance analysis of a product coupling geometric and architectural specifications in a probabilistic approach

International audienc