Influence of hysteresis on the transient hygrothermal response of a hemp concrete wall

Building envelopes with bio-materials like hemp concrete are currently undergoing an increasing development due to their low environmental impact and their interesting hygrothermal properties. This kind of hygroscopic material is characterized by a hysteretic behaviour. In this paper, the influence of such behaviour on the hygrothermal response of a building wall is discussed. An experimental facility is designed to measure temperature and relative humidity within a hemp concrete wall submitted to climatic variations. This facility provides a set of experimental data suited for benchmarking. Numerical simulations are performed with a hysteresis model implemented in a heat and moisture transfer model. Comparisons between numerical and experimental results show that hysteresis modelling is relevant to simulate the hygrothermal response of the wall. The discussion is extended to the influence of the initial moisture content.     

Monitoring ligand modulation of protein-protein interactions by mass spectrometry: estrogen receptor alpha-SRC1

Many drugs and chemicals exert their biological effect by modulating protein-protein interactions. In vitro approaches to characterize these mechanisms are often based on indirect measurements (e.g., fluorescence). Here, we used mass spectrometry (MS) to directly monitor the effect of small-molecule ligands on the binding of a coactivator peptide (SRC1) by the human estrogen receptor alpha ligand binding domain (hERalpha LBD). Nanoelectrospray mass spectrometry (nanoESI-MS) and high-mass matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) combined with chemical cross-linking were employed to follow these processes. The chemical cross-linking protocol used prior to high-mass MALDI analysis allows detection of intact noncovalent complexes. The binding of intact hERalpha LBD homodimer with two coactivator peptides was detected with nanoESI-MS and high-mass MALDI-MS only in the presence of an agonist ligand. Furthermore, high-mass MALDI-MS revealed an increase of the homodimer abundance after incubating the receptor with a ligand, independent of the ligand character (i.e., agonist, antagonist). The binding characteristics of the compounds tested by MS correlate very well with their biological activity reported by cell-based assays. High-mass MALDI appears to be an efficient and simple tool for directly monitoring ligand regulation mechanisms involved in protein-protein interactions. Furthermore, the combination of both MS methods allows identifying and characterizing endocrine-disrupting compounds or new drug compounds in an efficient way.     

Implications of Lactobacillus collinoides and Brettanomyces/Dekkera anomala in phenolic off-flavour defects of ciders

Different Lactobacillus collinoides and Brettanomyces/Dekkera anomala cider strains were studied for their ability to produce volatile phenols in synthetic medium. All strains were able to produce 4-ethylcatechol (4-EC), 4-ethylphenol (4-EP) and 4-ethylguaiacol (4-EG) from caffeic, p-coumaric and ferulic acids, respectively. Interestingly, D. anomala and L. collinoides were also able to produce 4-EC, 4-EP and 4-EG in cider conditions. The quantities of ethylphenols produced by these two species were similar in both tested ciders. The impact of precursor quantities was studied and it showed that the addition of caffeic and p-coumaric acids in ciders allowed for higher 4-EC and 4-EP production by D. anomala and L. collinoides. In parallel, D. anomala and L. collinoides strains were isolated from a phenolic off-flavour defective bottled cider after ethylphenol production hence confirming the implication of these two species in this cider spoilage. Finally, detection thresholds of the main ethylphenols were determined in ciders by orthonasal and retronasal sampling. The 4-EC and 4-EP detection thresholds (close to 20-25mg/l and 1.5-2.0mg/l, respectively) were matrix dependant.     

Effect of the size and interface composition of milk fat globules on their in vitro digestion by the human pancreatic lipase: Native versus homogenized milk fat globules

Although the bioavailability of dietary lipids is of primary importance in human nutrition and health, the mechanisms involved in lipid digestion are not fully understood and are of growing interest. The objective of this study was to determine the effect of the size of milk fat globules and of the composition of their interface on the activity of the human pancreatic lipase (PL). Native milk fat globules of various sizes covered by their biological membrane (MFGM) and homogenized fat globules of various sizes covered by milk proteins were prepared from whole milk and underwent lipolysis by the human PL with colipase and bile salts. A lag phase preceding the hydrolysis of milk TAG occurred with all native milk fat globules samples but not with homogenized milk samples. The kinetic parameters of human PL were determined by measuring the enzyme activity either after the lag phase for native milk fat globules samples or immediately after the addition of the enzyme for homogenized milk samples. The catalytic efficiency of human PL is 4.6-fold higher on small (1.8 μm) than large (6.7 μm) native milk fat globules, related to a 3.6-fold larger available surface. Despite the 25-fold larger available surface, milk TAG from homogenized milk are only 2-fold better hydrolyzed compared to native milk fat globules, as a possible result of a less favourable interface covered by milk proteins. The potential mechanisms involved in native vs. homogenized milk fat globules digestion by the human PL are discussed. Our study highlights the crucial role of the MFGM in the efficient digestion of milk fat globules and brings new insight for the design of dairy products and infant formulas.     

Personalization of cardiac motion and contractility from images using variational data assimilation

Personalization is a key aspect of biophysical models in order to impact clinical practice. In this paper, we propose a personalization method of electromechanical models of the heart from cine-MR images based on the adjoint method. After estimation of electrophysiological parameters, the cardiac motion is estimated based on a proactive electromechanical model. Then cardiac contractilities on two or three regions are estimated by minimizing the discrepancy between measured and simulation motion. Evaluation of the method on three patients with infarcted or dilated myocardium is provided.     

Enzymatic browning reactions in apple and apple products

This review examines the parameters of enzymatic browning in apple and apple products that is, phenolic compounds, polyphenoloxidases, and other factors (ascorbic acid and peroxidases), both qualitatively and quantitatively. Then the relationships between intensity of browning and the browning parameters are discussed, including a paragraph on the methods used for browning evaluation. Finally, the different methods for the control of browning are presented.     

A quasi-chemical model for the growth and death of microorganisms in foods by non-thermal and high-pressure processing

Predictive microbial models generally rely on the growth of bacteria in laboratory broth to approximate the microbial growth kinetics expected to take place in actual foods under identical environmental conditions. Sigmoidal functions such as the Gompertz or logistics equation accurately model the typical microbial growth curve from the lag to the stationary phase and provide the mathematical basis for estimating parameters such as the maximum growth rate (MGR). Stationary phase data can begin to show a decline and make it difficult to discern which data to include in the analysis of the growth curve, a factor that influences the calculated values of the growth parameters. In contradistinction, the quasi-chemical kinetics model provides additional capabilities in microbial modelling and fits growth-death kinetics (all four phases of the microbial lifecycle continuously) for a general set of microorganisms in a variety of actual food substrates. The quasi-chemical model is differential equations (ODEs) that derives from a hypothetical four-step chemical mechanism involving an antagonistic metabolite (quorum sensing) and successfully fits the kinetics of pathogens (Staphylococcus aureus, Escherichia coli and Listeria monocytogenes) in various foods (bread, turkey meat, ham and cheese) as functions of different hurdles (a_w, pH, temperature and anti-microbial lactate). The calculated value of the MGR depends on whether growth-death data or only growth data are used in the fitting procedure. The quasi-chemical kinetics model is also exploited for use with the novel food processing technology of high-pressure processing. The high-pressure inactivation kinetics of E. coli are explored in a model food system over the pressure (P) range of 207–345 MPa (30,000–50,000 psi) and the temperature (T) range of 30–50 °C. In relatively low combinations of P and T, the inactivation curves are non-linear and exhibit a shoulder prior to a more rapid rate of microbial destruction. In the higher P, T regime, the inactivation plots tend to be linear. In all cases, the quasi-chemical model successfully fit the linear and curvi-linear inactivation plots for E. coli in model food systems. The experimental data and the quasi-chemical mathematical model described herein are candidates for inclusion in ComBase, the developing database that combines data and models from the USDA Pathogen Modeling Program and the UK Food MicroModel.     

Opportunities in public policy to support infant and early childhood mental health: The role of psychologists and policymakers.

Infant and early childhood mental health practices can be supported by policies and professional standards of care that foster the healthy development of young children. Policies that support infants and toddlers include those that strengthen their families to provide a family environment that promotes mental wellness. Policy issues for infants, toddlers, and young children have come to the forefront of thinking as children need a “voice” to advocate for their support and care. This article (a) highlights several important policy areas that support the social–emotional development of very young children and (b) gives examples of current policy accomplishments and challenges. The article offers a policy agenda to promote the mental health of infants and young children and suggests ways that psychologists can engage with policymakers to promote policies that foster infant mental health, including contributing to the knowledge base that informs policy decisions, educating the public and policymakers about early childhood development and mental wellness, forming community partnerships to identify and address infant mental health risks, and participating in the development of policy recommendations that improve access to evidence-based practices in infant mental health. (PsycINFO Database Record (c) 2010 APA, all rights reserved)