Heat transfer correlation for flow boiling in small to micro tubes

This article is available open access under a Creative Commons license (http://creativecommons.org/licenses/by-nc-nd/3.0/) Copyright © 2013 The Authors. Published by Elsevier Ltd. All rights reserved.There is a large discrepancy in the open literature about the comparative performance of the existing macro and microscale heat transfer models and correlations when applied to small/micro flow boiling systems. This paper presents a detailed comparison of the flow boiling heat transfer coefficient for R134a in stainless steel micro tubes with 21 macro and microscale correlations and models. The experimental database that was used in the comparison includes the data for 1.1 and 0.52 mm diameter tubes, mass flux range of 100–500 kg/m2 s and system pressure range 6–10 bar obtained in the course of this study. The effect of the evaporator heated length on the comparative performance of the correlations and models was investigated using three different lengths of the 1.1 mm diameter tube (L = 150, 300 and 450 mm). This comparative study demonstrated that none of the assessed models and correlations could predict the experimental data with a reasonable accuracy. Also, the predictability of most correlations becomes worse as the heated length increases. This may contribute in explaining the discrepancy in the comparative performance of the correlations from one study to another. A new correlation is proposed in the present study based on the superposition model of Chen. The database used in developing the correlation consists of 5152 data points including the current experimental data and data obtained previously with the same test rig, fluid and methodology for tubes of diameter 4.26, 2.88, 2.01 mm. The new correlation predicted 92% of the data within the ±30% error bands with a MAE value of 14.3%

The design of naproxen solid lipid nanoparticles to target skin layers

The aim of the current investigation was to produce naproxen solid lipid nanoparticles (Nap-SLNs) by the ultrasonication method to improve its skin permeation and also to investigate the influence of Hydrophilic-lipophilic balance (HLB) changes on nanoparticles properties. The properties of obtained SLNs loaded with naproxen were characterized by photon correlation spectroscopy (PCS), transmission electron microscopy (TEM) and differential scanning calorimetry (DSC). FT-IR was also used to investigate any interaction between naproxen and the excipients used at the molecular level during the preparation of the SLNs. The performance of the formulations was investigated in terms of skin permeation and also the retention of the drug by the skin. It was found that generally, with increasing the lipid concentration, the average particle size and polydispersity index (PDI) of SLNs increased from 94.257 ± 4.852 nm to 143.90 ± 2.685 nm and from 0.293 ± 0.037 to 0.525 ± 0.038 respectively. The results also showed that a reduction in the HLB resulted in an increase in the PDI, particle size, zeta potential and entrapment efficiency (EE %). DSC showed that the naproxen encapsulated in the SLNs was in its amorphous form. The peaks of prominent functional groups of naproxen were found in the FT-IR spectra of naproxen-SLN, which confirmed the entrapment of naproxen in the lipid matrix. FT-IR results also ruled out any chemical interaction between drug and the chemicals used in the preparation of SLNs. The amount of naproxen detected in the receptor chamber at all the sampling times for the reference formulation (naproxen solution containing all surfactants at pH 7.4) was higher than that of the Nap-SLN8 formulation. Nap-SLN8 showed an increase in the concentration of naproxen in the skin layer with less systemic absorption. This indicates that most of the drug in Nap-SLN8 remains in the skin which can reduce the side effect of systemic absorption of the drug and increases the concentration of the drug at the site of the action

Glucocorticoids—All-Rounders Tackling the Versatile Players of the Immune System

Glucocorticoids regulate fundamental processes of the human body and control cellular functions such as cell metabolism, growth, differentiation, and apoptosis. Moreover, endogenous glucocorticoids link the endocrine and immune system and ensure the correct function of inflammatory events during tissue repair, regeneration, and pathogen elimination via genomic and rapid non-genomic pathways. Due to their strong immunosuppressive, anti-inflammatory and anti-allergic effects on immune cells, tissues and organs, glucocorticoids significantly improve the quality of life of many patients suffering from diseases caused by a dysregulated immune system. Despite the multitude and seriousness of glucocorticoid-related adverse events including diabetes mellitus, osteoporosis and infections, these agents remain indispensable, representing the most powerful, and cost-effective drugs in the treatment of a wide range of rheumatic diseases. These include rheumatoid arthritis, vasculitis, and connective tissue diseases, as well as many other pathological conditions of the immune system. Depending on the therapeutically affected cell type, glucocorticoid actions strongly vary among different diseases. While immune responses always represent complex reactions involving different cells and cellular processes, specific immune cell populations with key responsibilities driving the pathological mechanisms can be identified for certain autoimmune diseases. In this review, we will focus on the mechanisms of action of glucocorticoids on various leukocyte populations, exemplarily portraying different autoimmune diseases as heterogeneous targets of glucocorticoid actions: (i) Abnormalities in the innate immune response play a crucial role in the initiation and perpetuation of giant cell arteritis (GCA). (ii) Specific types of CD4+ T helper (Th) lymphocytes, namely Th1 and Th17 cells, represent important players in the establishment and course of rheumatoid arthritis (RA), whereas (iii) B cells have emerged as central players in systemic lupus erythematosus (SLE). (iv) Allergic reactions are mainly triggered by several different cytokines released by activated Th2 lymphocytes. Using these examples, we aim to illustrate the versatile modulating effects of glucocorticoids on the immune system. In contrast, in the treatment of lymphoproliferative disorders the pro-apoptotic action of glucocorticoids prevails, but their mechanisms differ depending on the type of cancer. Therefore, we will also give a brief insight into the current knowledge of the mode of glucocorticoid action in oncological treatment focusing on leukemia

Fundamental issues, mechanisms and models of flow boiling heat transfer in microscale channels

This paper presents state-of-the-art review on the fundamental and frontier research of flow boiling heat transfer, mechanisms and prediction methods including models and correlations for heat transfer in microscale channels. First, fundamental issues of current research on flow boiling in microscale channels are addressed. These mainly include the criteria for macroscale and microscale channels. Then, studies on flow boiling heat transfer behaviours and mechanisms in microscale channels are presented. Next, the available correlations and models of flow boiling heat transfer in microscale channels are reviewed and analysed. Comparisons of 12 correlations with a database covering a wide range of test parameters and 8 fluids are presented. It shows that all correlations poorly agree to the database. No generalized model or correlation is able to predict all flow boiling heat transfer data. Furthermore, comparisons of the mechanistic flow boiling heat transfer models based on flow patterns including the Thome et al. three-zone heat transfer model for evaporation in microchannel and the flow pattern based model combining the Thome et al. three zone heat transfer models with the Cioncolini-Thome annular flow model for both macro- and microchannel to the database are presented. It shows that the flow pattern based model combining the three zone model with the annular flow model gives better prediction than the three zone heat transfer model alone. The flow pattern based heat transfer model favourably agrees with the experimental database collected from the literature. According to the comparison and analysis, suggestions have been given for improving the prediction methods in the future. Next, flow patterned based phenomenological models and their applications to microscale channels are presented. Finally, as an important topic, unstable and transient flow boiling phenomena in microscale channels are briefed and recommendations for future research are given. According to this comprehensive review and analysis of the current research on the fundamental issues of flow boiling, mechanisms and prediction methods in microscale channels, the future research needs have been identified and recommended. In general, systematic and accurate experimental data of flow boiling heat transfer in microscale channels are still needed although a large amount of work has been done over the past decades. The channel size effect on the flow boiling behaviours should be systematically investigated. Heat transfer mechanisms in microscale channels should be further understood and related to the corresponding flow patterns. Furthermore, effort should be made to develop and improve generalized mechanistic prediction methods and theoretical models for flow boiling heat transfer in microscale channels according to the physical phenomena/mechanisms and the corresponding flow structures. The effects of the channel size and a wide range of test conditions and fluid types should be considered in develop new methods. Furthermore, systematic experimental, analytical and modeling studies on unstable and transient flow boiling heat transfer in microscale channels should be conducted to understand the physical mechanisms and theoretical models

Physical Exercise following bariatric surgery in women with Morbid obesity Study protocol clinical trial (SPIRIT compliant)

Background: Severe and morbid obesity are increasing globally, particularly in women. As BMI increases, the likelihood of anovulation is higher. The primary aim of the EMOVAR clinical trial is to examine, over the short (16 weeks) and medium (12 months) term, the effects of a supervised physical exercise program (focused primarily on aerobic and resistance training) on ovarian function in women with severe/morbid obesity who have undergone bariatric surgery. Secondary objectives are to examine the effects of the intervention on chronic inflammation, insulin resistance, arterial stiffness, physical fitness, and health-related quality of life. Methods: This is a randomized controlled trial in which ∼40 female bariatric surgery patients, aged between 18 and 45 years old, will be included. Participants assigned to the experimental group will perform a total of 48 sessions of supervised concurrent (strength and aerobic) training (3sessions/week, 60min/session) spread over 16 weeks. Patients assigned to the control group will receive lifestyle recommendations. Outcomes will be assessed at baseline, week 16 (i.e., after the exercise intervention) and 12 months after surgery. The primary outcome is ovarian function using the Sex-Hormone Binding Globuline, measured in serum. Secondary outcomes are serum levels of anti-mullerian hormone, TSH, T4, FSH, LH, estradiol, prolactine, and free androgen index, as well as oocyte count, the diameters of both ovaries, endometrial thickness, and uterine arterial pulsatility index (obtained from a transvaginal ultrasound), the duration of menstrual bleeding and menstrual cycle duration (obtained by personal interview) and hirsutism (Ferriman Gallwey Scale). Other secondary outcomes include serummarkers of chronic inflammation and insulin resistance (i.e., C-reactive protein, interleukin 6, tumor necrosis factor-alpha, leptin, glomerular sedimentation rate, glucose, insulin and theHOMA-IR), arterial stiffness, systolic, diastolic and mean blood pressure, body composition, and total weight loss. Physical fitness (including cardiorespiratory fitness, muscular strength, and flexibility), health-related quality of life (SF-36 v2) and sexual function (Female Sexual Function Index) will also be measured. Discussion: This study will provide, for the first time, relevant information on the effects of exercise training on ovarian function and underlying mechanisms in severe/morbid obese women following bariatric surgery.This work was supported by Ministerio de Economía y Competitividad (MINECO), Plan Nacional de I+D+i call RETOS 2018 (grant n° RTI2018-093302-A-I00). EM-R was funded by the Spanish Ministry of Science, Innovation and Universities (FPU18/01107) and AH-M by the Gerty Cory pre-doctoral program for deficit areas at the University of Almería

Novel quantitative trait locus is mapped to chromosome 12p11 for left ventricular mass in Dominican families: the Family Study of Stroke Risk and Carotid Atherosclerosis

<p>Abstract</p> <p>Background</p> <p>Left ventricular mass (LVM) is an important risk factor for stroke and vascular disease. The genetic basis of LVM is unclear although a high heritability has been suggested. We sought to map quantitative trait loci (QTL) for LVM using large Dominican families.</p> <p>Methods</p> <p>Probands were selected from Dominican subjects of the population-based Northern Manhattan Study (NOMAS). LVM was measured by transthoracic echocardiography. A set of 405 microsatellite markers was used to screen the whole genome among 1360 subjects from 100 Dominican families who had complete phenotype data and DNA available. A polygenic covariate screening was run to identify the significant covariates. Variance components analysis was used to estimate heritability and to detect evidence for linkage, after adjusting for significant risk factors. Ordered-subset Analysis (OSA) was conducted to identify a more homogeneous subset for stratification analysis.</p> <p>Results</p> <p>LVM had a heritability of 0.58 in the studied population (p < 0.0001). The most significant evidence for linkage was found at chromosome 12p11 (MLOD = 3.11, empirical p = 0.0003) with peak marker at D12S1042. This linkage was significantly increased in a subset of families with the high average waist circumference (MLOD = 4.45, p = 0.0045 for increase in evidence for linkage).</p> <p>Conclusion</p> <p>We mapped a novel QTL near D12S1042 for LVM in Dominicans. Enhanced linkage evidence in families with larger waist circumference suggests that gene(s) residing within the QTL interact(s) with abdominal obesity to contribute to phenotypic variation of LVM. Suggestive evidence for linkage (LOD = 1.99) has been reported at the same peak marker for left ventricular geometry in a White population from the HyperGEN study, underscoring the importance of this QTL for left ventricular phenotype. Further fine mapping and validation studies are warranted to identify the underpinning genes.</p

In Vivo Methods for the Assessment of Topical Drug Bioavailability

This paper reviews some current methods for the in vivo assessment of local cutaneous bioavailability in humans after topical drug application. After an introduction discussing the importance of local drug bioavailability assessment and the limitations of model-based predictions, the focus turns to the relevance of experimental studies. The available techniques are then reviewed in detail, with particular emphasis on the tape stripping and microdialysis methodologies. Other less developed techniques, including the skin biopsy, suction blister, follicle removal and confocal Raman spectroscopy techniques are also described

CMS physics technical design report : Addendum on high density QCD with heavy ions

Peer reviewe

Multi-messenger observations of a binary neutron star merger

On 2017 August 17 a binary neutron star coalescence candidate (later designated GW170817) with merger time 12:41:04 UTC was observed through gravitational waves by the Advanced LIGO and Advanced Virgo detectors. The Fermi Gamma-ray Burst Monitor independently detected a gamma-ray burst (GRB 170817A) with a time delay of ~1.7 s with respect to the merger time. From the gravitational-wave signal, the source was initially localized to a sky region of 31 deg2 at a luminosity distance of 40+8-8 Mpc and with component masses consistent with neutron stars. The component masses were later measured to be in the range 0.86 to 2.26 Mo. An extensive observing campaign was launched across the electromagnetic spectrum leading to the discovery of a bright optical transient (SSS17a, now with the IAU identification of AT 2017gfo) in NGC 4993 (at ~40 Mpc) less than 11 hours after the merger by the One- Meter, Two Hemisphere (1M2H) team using the 1 m Swope Telescope. The optical transient was independently detected by multiple teams within an hour. Subsequent observations targeted the object and its environment. Early ultraviolet observations revealed a blue transient that faded within 48 hours. Optical and infrared observations showed a redward evolution over ~10 days. Following early non-detections, X-ray and radio emission were discovered at the transient’s position ~9 and ~16 days, respectively, after the merger. Both the X-ray and radio emission likely arise from a physical process that is distinct from the one that generates the UV/optical/near-infrared emission. No ultra-high-energy gamma-rays and no neutrino candidates consistent with the source were found in follow-up searches. These observations support the hypothesis that GW170817 was produced by the merger of two neutron stars in NGC4993 followed by a short gamma-ray burst (GRB 170817A) and a kilonova/macronova powered by the radioactive decay of r-process nuclei synthesized in the ejecta