Sensible Heat Transfer during Droplet Cooling:Experimental and Numerical Analysis

This study presents the numerical reproduction of the entire surface temperature field resulting from a water droplet spreading on a heated surface, which is compared with experimental data. High-speed infrared thermography of the back side of the surface and high-speed images of the side view of the impinging droplet were used to infer on the solid surface temperature field and on droplet dynamics. Numerical reproduction of the phenomena was performed using OpenFOAM CFD toolbox. An enhanced volume of fluid (VOF) model was further modified for this purpose. The proposed modifications include the coupling of temperature fields between the fluid and the solid regions, to account for transient heat conduction within the solid. The results evidence an extremely good agreement between the temporal evolution of the measured and simulated spreading factors of the considered droplet impacts. The numerical and experimental dimensionless surface temperature profiles within the solid surface and along the droplet radius, were also in good agreement. Most of the differences were within the experimental measurements uncertainty. The numerical results allowed relating the solid surface temperature profiles with the fluid flow. During spreading, liquid recirculation within the rim, leads to the appearance of different regions of heat transfer that can be correlated with the vorticity field within the droplet

Sweat gland recruitment following thermal and psychological stimuli

Eccrine sweat glands are present across almost the entire body surface. The distinction between glabrous (hairless) and non-glabrous skin has frequently been used to describe differences in human sudomotor function and, in particular, to help differentiate between the thermal and nonthermal mechanisms that modulate sweat secretion. Indeed, the widely accepted consensus is that psychological (psychogenic) sweating is limited to the glabrous regions, while thermally induced secretion occurs only from non-glabrous surfaces (Iwase et al., 1997). Furthermore, it is frequently assumed that independent central controllers, efferent pathways and different neurotransmitters activate the sweat glands within each of these regions. A recent research focus of the current laboratory has been to evaluate the veracity of these assumptions

Lignin-enriched tricalcium phosphate/sodium alginate 3D scaffolds for application in bone tissue regeneration

The bone is a connective, vascularized, and mineralized tissue that confers protection to organs, and participates in the support and locomotion of the human body, maintenance of homeostasis, as well as in hematopoiesis. However, throughout the lifetime, bone defects may arise due to traumas (mechanical fractures), diseases, and/or aging, which when too extensive compromise the ability of the bone to self-regenerate. To surpass such clinical situation, different therapeutic approaches have been pursued. Rapid prototyping techniques using composite materials (consisting of ceramics and polymers) have been used to produce customized 3D structures with osteoinductive and osteoconductive properties. In order to reinforce the mechanical and osteogenic properties of these 3D structures, herein, a new 3D scaffold was produced through the layer-by-layer deposition of a tricalcium phosphate (TCP), sodium alginate (SA), and lignin (LG) mixture using the Fab@Home 3D-Plotter. Three different TCP/LG/SA formulations, LG/SA ratio 1:3, 1:2, or 1:1, were produced and subsequently evaluated to determine their suitability for bone regeneration. The physicochemical assays demonstrated that the LG inclusion improved the mechanical resistance of the scaffolds, particularly in the 1:2 ratio, since a 15 % increase in the mechanical strength was observed. Moreover, all TCP/LG/SA formulations showed an enhanced wettability and maintained their capacity to promote the osteoblasts' adhesion and proliferation as well as their bioactivity (formation of hydroxyapatite crystals). Such results support the LG inclusion and application in the development of 3D scaffolds aimed for bone regeneration.info:eu-repo/semantics/publishedVersio

Mucoid morphotype variation of Burkholderia multivorans during chronic cystic fibrosis lung infection is correlated with changes in metabolism, motility, biofilm formation and virulence

Burkholderia cepacia complex (Bcc) bacteria are opportunistic pathogens infecting hosts such as cystic fibrosis (CF) patients. Long-term Bcc infection of CF patients' airways has been associated with emergence of phenotypic variation. Here we studied two Burkholderia multivorans clonal isolates displaying different morphotypes from a chronically infected CF patient to evaluate trait development during lung infection. Expression profiling of mucoid D2095 and non-mucoid D2214 isolates revealed decreased expression of genes encoding products related to virulence-associated traits and metabolism in D2214. Furthermore, D2214 showed no exopolysaccharide production, lower motility and chemotaxis, and more biofilm formation, particularly under microaerophilic conditions, than the clonal mucoid isolate D2095. When Galleria mellonella was used as acute infection model, D2214 at a cell number of approximately 7×10(6) c.f.u. caused a higher survival rate than D2095, although 6 days post-infection most of the larvae were dead. Infection with the same number of cells by mucoid D2095 caused larval death by day 4. The decreased expression of genes involved in carbon and nitrogen metabolism may reflect lower metabolic needs of D2214 caused by lack of exopolysaccharide, but also by the attenuation of pathways not required for survival. As a result, D2214 showed higher survival than D2095 in minimal medium for 28 days under aerobic conditions. Overall, adaptation during Bcc chronic lung infections gave rise to genotypic and phenotypic variation among isolates, contributing to their fitness while maintaining their capacity for survival in this opportunistic human niche

Personality and well-being in adolescents

Different profiles of the character dimensions of self-directedness, cooperativeness and self-transcendence result in different levels of wellbeing among adults. However, the description of the multidimensional character profiles on adolescents’ composite wellbeing remains unexplored. This study builds on previous studies with adults, and examines the linear and non-linear associations between the dimensions of the psychobiological model of personality and well-being in adolescents. Participated in this study 1540 adolescents (M=15.44, SD=1.731). Personality was assessed using the Temperament and Character Inventory (TCI). Well-being was evaluated in a composite perspective: satisfaction with social support, health-related quality of life, satisfaction with life and affect. Variable-centered and individual-centered analyses were performed.Self-directedness was strongly associated with all dimensions of affective and cognitive well-being regardless of the other two character traits. Cooperativeness was associated with non-affective well-being and with positive affect, but only when associated to elevation of Self-directedness and Self-transcendence. Self-Directedness and Cooperativeness explained 15.5% of the non-affective well-being variance. Self-Directedness and Self-Transcendence explained 10.4% of the variance in affective well-being. This study confirms the tendencies found in previous studies with adults from other societies, where each character dimension gives an independent contribution to well-being depending on the interactions with other Character dimensions. Also, this study highlights the importance of considering the non-linear influences of the character dimensions in understanding of adolescents’ wellbeing. These results have strong implications for youth positive mental health promotion, including for school-based policies and practices

Effect of wettability on nucleate boiling

Papers presented to the 11th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, South Africa, 20-23 July 2015.Heat transfer enhancement at liquid-solid interfaces is often achieved by modifying the surface properties. However, deep efforts to describe the actual role of surface modification only started at the 1980’s and much work has left undone since then. The wettability is a key parameter governing heat, mass and momentum transport at liquid-solid interfaces. However it is usually quantified using macroscopic quantities, which cannot be related with the micro-and-nano-scale phenomena occurring at the interface. In this context, the present paper revises the potential and limitations of using macroscopic apparent contact angles to predict the wetting regimes. Then, these angles are used to relate the wetting regimes with bubble dynamics and heat transfer processes occurring at pool boiling. The results show that the macroscopic angles are useful to establish general trends and differentiate bubble dynamics behaviour occurring for opposite wetting regimes. However, milder wetting changes occurring within each regime, caused, for instance, by surface topography are not well captured by the apparent angle, as the surface topography is not scaled to affect this macroscopic angle, although it can clearly influence the bubble formation and departure mechanisms and, consequently the heat transfer coefficients. In line with this, the concept of the micro-scale contact angle, as introduced by Phan et al. [1] is used here together with a geometrical parameter to include the effect of surface topography, to describe the role of the wettability on bubble dynamics. Based on this analysis, a multi-scale approach is proposed to include the role of wettability on correlations predicting the pool boiling heat transfer coefficients.am201

Tandem Thio-Michael Addition/Remote Lactone Activation of 5-Hydroxymethylfurfural-Derived δ-Lactone-Fused Cyclopentenones

Funding Information: We thank the Fundação para a Ciência e a Tecnologia (SFRH/BD/120829/2016, SFRH/BD/148211/2019, UIDB/04138/2020, UIDP/04138/2020, PTDC/QUI‐QOR/32008/2017 and GHTM‐UID/04413/2020). The project leading to this application has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No 951996. J. A. S. C. thanks the Fundação para a Ciência e a Tecnologia (FCT) for Scientific Employment Stimulus 2020/02383/CEECIND. Publisher Copyright: © 2022 The Authors. ChemSusChem published by Wiley-VCH GmbH.The creation of structurally diverse chemical entities from fairly simple biorefinery products remains a challenge. In this work 5-hydroxymethylfurfural (HMF) was identified as a key synthon for preparing highly complex cyclopentenones (CP) via tandem 1,4-addition/elimination/remote lactone activation to external O- and N-nucleophiles in δ-lactone-fused-CPs hotspots. This scaffold was also reactive enough to be incorporated into model cysteine-peptides in low concentrations, paving the way to a potential translation generating complexity in the synthesis of small peptides. The new enones also exhibited activity against intraerythrocytic Plasmodium falciparum (IC50=1.32 μm).publishersversionpublishe

Design data for footwear: sweating distribution on the human foot

Purpose – The purpose of this paper is to provide footwear designers, manikin builders and thermo-physiological modellers with sweat distribution information for the human foot. Design/methodology/approach – Independent research from two laboratories, using different techniques, is brought together to describe sweat production of the foot. In total, 32 individuals were studied. One laboratory used running at two intensities in males and females, and measured sweat with absorbents placed inside the shoe. The other used ventilated sweat capsules on a passive, nude foot, with sweating evaluated during passive heating and incremental exercise to fatigue. Findings – Results from both laboratories are in agreement. Males secreted more than twice the volume of sweat produced by the females (p<0.01) at the same relative work rate. Both genders demonstrated a non-uniform sweat distribution, though this was less variable in females. Highest local sweat rates were observed from the medial ankles (p<0.01). The dorsal foot sweated substantially more than the plantar (sole) areas (p<0.01). Sweating on the plantar side of the foot was uniform. Wearing shoes limited the increase in sweat production with increasing load, while the sweat rate of uncovered feet kept increasing with work and thermal load. Practical implications – The observed variation in sweat rate across the foot shows that footwear design should follow the body mapping principle. Fabrics and materials with different properties can be used to improve comfort if applied to different foot surfaces. The data also demonstrate that foot models, whether physical (manikins) or mathematical, need to incorporate the observed variation across the foot to provide realistic simulation/testing of footwear