DEVELOPMENT OF A CACO2/HT-29 70/30 CO-CULTURE AS AN IN VITRO MODEL OF HEALTHY OR OBESE HUMAN INTESTINE AND ITS VALIDATION FOR STUDYING NUTRIENT/INTESTINE INTERACTIONS AT MOLECULAR AND BIOCHEMICAL LEVEL

The Ph.D. project has been structured in three different parts: The first one focused on setting up and characterizing a 70/30 Caco2/HT-29 co-culture as an in vitro model to mimic the physiology of the human intestinal epithelium starting from the two parental cell populations already differentiated. The co-culture morpho-functional features were analyzed at confluence (T0) and 3, 6, 10 and 14 days after T0 (T3, T6, T10 and T14, respectively). Morphological analysis revealed: at T6, the presence of microvilli, a complete paracellular junctional apparatus and mucus; at T14, abundant microvilli and mucus absence. The functional analysis showed: an increase of Alkaline Phosphatase, Aminopeptidase N and Dipeptidyl Peptidase IV specific activity with days in culture, indicative of a progressive acquisition of a differentiated intestinal phenotype; permeability values comparable to the ones of the human small intestine and indicative of a good status of the tight junctions. This co-culture could be considered a more versatile, suitable and simpler in vitro model of human small intestinal epithelium, than the previous published ones, able to reach the intestinal differentiated phenotype already after six days from the confluence. The second part focused on the validation of the 70/30 Caco2/HT-29 co-culture as model to study absorption and nutrient/food-intestine interactions at molecular and biochemical level. Five different experimental water biscuits and breads were subjected to an in vitro gastrointestinal digestion and the obtained digestates were administered to the co-culture at physiological doses, calculated starting from the daily recommended dose in relation to the total surface area of intestinal absorption, and in excess. The effect of digestates administration on co-culture cell viability, paracellular permeability, oxidative status and anorectic hormones production were evaluated: all the digestates were not able to affect co-culture viability or to modify the paracellular permeability; all the water biscuit digestates were able to reduce intracellular ROS formation due to the natural presence of antioxidant compounds in the flours used to prepare them; all the bread samples were able to modulate the co-culture anorectic hormone production. These studies showed the suitability of the co-culture to study a wide range of interactions between nutrients/food/nutraceuticals and intestine. The third part focused on setting up and characterizing an in vitro cellular model of obese/overweight intestine using the 70/30 Caco2/HT-29 co-culture. The nutrient excess was mimed increasing the frequency of medium change compared to the standard condition and the co-culture morpho-functional features were analyzed at 3, 7, 11 and 15 days after confluence (T3, T7, T11 and T15, respectively). The obtained in vitro model, after 15 days of post-confluence and compared to our standard co-culture, showed a higher: i) inflammatory and oxidative status; ii) paracellular permeability; iii) microvilli enzyme activity; iv) production of anorectic hormones. These features were comparable to the ones revealed in vivo in the intestine of obese subjects, thus validating the present cellular model to study obesity-associated modifications at the molecular level

An Analytic Model for Estimating the Economic and Environmental Impact of Food Cold Supply Chain

Cold chain management has gained increasing interest among practitioners, researchers and academics; similarly, sustainability is also proving to be an increasingly critical topic in all supply chains and in cold chains in particular. In line with this, this study proposes a model to estimate the economic and environmental impacts in a food cold supply chain (FCSC). The model intended to estimate the total cost and CO2 emissions of a company operating in the cold supply chain, was carried out in Microsoft Excel™. Specifically, the model reproduces the main FCSC processes, i.e., Product collection, Backroom storage, Product delivery and Reverse logistics. For each process, we have exposed the implemented equations. Results show that the product delivery process is the most critical in both economic and environmental terms. Conversely, product collection and reverse logistics process contribute to the total cost and emission to a limited extent. The results obtained provide useful guidelines for supply chain managers to undertake operation decisions aimed at decreasing the economic and/or environmental impact of a FCSC

Assessment of the economic and environmental sustainability of a food cold supply chain

Based on environmental and economic factors, reverse logistics (RL) issues have attracted attention among both academia and practitioners. This study investigates the issue of economic and environmental sustainability evaluation in a food cold supply chain (FCSC), which carries out four main different processes, i.e. product collection, backroom storage, products delivery and RL. For the RL process, which is taken as an example, we have detailed the equations implemented in an analytic model to carry out the computation of the economic and environmental sustainability, while for the remaining processes, we present and discuss only the main results obtained. The model was developed under Microsoft Excel™ and is intended to assess the total cost and CO2 emissions of an important company operating as a cold chain logistics service provider. Results of the model show that the highest total cost and environmental impact are due to the product delivery process. Moreover, the results proposed indicate quite clearly the specific activity component where the FCSC managers should intervene to remove or decrease possible inefficiencies and optimize or increase the sustainability of a FCSC

Problemas cuantitativos y comprensión de conceptos

Los docentes de química a nivel universitario usamos «problemas», habitualmente de tipo cuantitativo, para enseñar y para evaluar. En este trabajo ponemos en duda de que lo hagamos en forma eficaz. Se muestra, a partir de pruebas diagnósticas de pares de problemas (uno cuantitativo y otro cualitativo similar), que muchos estudiantes pueden resolver los problemas cuantitativos sin una adecuada comprensión conceptual.Chemistry professors at university level make use of «problems», usually of a quantitative type, to teach and evaluate. In this article we question the fact of whether they do it in an efficient way. From diagnostic test of pairs of problems (a quantitative and a similar qualitative one) it is shown that many students can solve quantitative problems without an appropriate conceptual comprehension

In vitro antioxidant properties of digests of hydrolyzed casein and caseinophosphopeptide preparations in cell models of human intestine and osteoblasts

Three commercial samples consisting of enriched calcium-free caseinophosphopeptides (CPP), enriched calcium-bound caseinophosphopeptides (Ca-CPP) and an enzymatically hydrolyzed casein (hCN) were in vitro digested according to COST-Infogest protocol. As assessed by UPLC-HR-MS/MS, the digests contained 207\u2013235 unique caseinophosphopeptides, and the species presenting the cluster sssEE were more abundant in CPP digest. The antioxidant activity at three different doses of each digest was firstly evaluated on human intestinal Caco-2/HT-29 70/30 co-culture. In presence of AAPH, hCN and CPP digests displayed a dose-dependent antioxidant activity equal or even greater than Vitamin C. In presence of Fe2+, the digests exerted an antioxidant activity mainly at the highest dose. Antioxidant activities of the intestinal metabolized digests was then evaluated on human osteoblast (Saos-2) cells. The digests exerted an antioxidant activity in presence of AAPH, but not in presence of Fe2+. These results highlight milk-derived peptides as potential dietary supplements for gut and bone health

Bulk Cr tips for scanning tunneling microscopy and spin-polarized scanning tunneling microscopy

A simple, reliable method for preparation of bulk Cr tips for Scanning Tunneling Microscopy (STM) is proposed and its potentialities in performing high-quality and high-resolution STM and Spin Polarized-STM (SP-STM) are investigated. Cr tips show atomic resolution on ordered surfaces. Contrary to what happens with conventional W tips, rest atoms of the Si(111)-7x7 reconstruction can be routinely observed, probably due to a different electronic structure of the tip apex. SP-STM measurements of the Cr(001) surface showing magnetic contrast are reported. Our results reveal that the peculiar properties of these tips can be suited in a number of STM experimental situations

Pulsed Laser Deposition of two-dimensional ZnO nanocrystals on Au(111): Growth, surface structure and electronic properties

Two-dimensional (2D) ZnO structures have been deposited on the Au(111) surface by means of the pulsed laser deposition (PLD) technique. In situ scanning tunneling microscopy (STM) and spectroscopy (STS) measurements have been performed to characterize morphological, structural and electronic properties of 2D ZnO at the nanoscale. Starting from a sub-monolayer coverage, we investigated the growth of ZnO, identifying different atomic layers (up to the 5th). At low coverage, we observed single- and bi-layer nanocrystals, characterized by a surface moire pattern that is associated to a graphene-like ZnO structure. By increasing the coverage, we revealed a morphological change starting from the 4th layer, which was attributed to a transition toward a bulk-like structure. Investigation of the electronic properties revealed the semiconducting character of 2D ZnO. We observed a dependence of the density of states (DOS) and, in particular, of the conduction band (CB) on the ZnO thickness, with a decreasing of the CB onset energy for increasing thickness. The CB DOS of 2D ZnO shows a step-like behaviour which may be interpreted as due to a 2D quantum confinement effect in ZnO atomic layer

Accuracy of dielectric-dependent hybrid functionals in the prediction of optoelectronic properties of metal oxide semiconductors: a comprehensive comparison with many-body GW and experiments

Understanding the electronic structure of metal oxide semiconductors is crucial to their numerous technological applications, such as photoelectrochemical water splitting and solar cells. The needed experimental and theoretical knowledge goes beyond that of pristine bulk crystals, and must include the effects of surfaces and interfaces, as well as those due to the presence of intrinsic defects (e.g. oxygen vacancies), or dopants for band engineering. In this review, we present an account of the recent efforts in predicting and understanding the optoelectronic properties of oxides using ab initio theoretical methods. In particular, we discuss the performance of recently developed dielectric-dependent hybrid functionals, providing a comparison against the results of many-body GW calculations, including G 0 W 0 as well as more refined approaches, such as quasiparticle self-consistent GW. We summarize results in the recent literature for the band gap, the band level alignment at surfaces, and optical transition energies in defective oxides, including wide gap oxide semiconductors and transition metal oxides. Correlated transition metal oxides are also discussed. For each method, we describe successes and drawbacks, emphasizing the challenges faced by the development of improved theoretical approaches. The theoretical section is preceded by a critical overview of the main experimental techniques needed to characterize the optoelectronic properties of semiconductors, including absorption and reflection spectroscopy, photoemission, and scanning tunneling spectroscopy (STS)

Low-frequency modes in the Raman spectrum of sp-sp2 nanostructured carbon

A novel form of amorphous carbon with sp-sp2 hybridization has been recently produced by supersonic cluster beam deposition showing the presence in the film of both polyynic and cumulenic species [L. Ravagnan et al. Phys. Rev. Lett. 98, 216103 (2007)]. Here we present a in situ Raman characterization of the low frequency vibrational region (400-800 cm-1) of sp-sp2 films at different temperatures. We report the presence of two peaks at 450 cm-1 and 720 cm-1. The lower frequency peak shows an evolution with the variation of the sp content and it can be attributed, with the support of density functional theory (DFT) simulations, to bending modes of sp linear structures. The peak at 720 cm-1 does not vary with the sp content and it can be attributed to a feature in the vibrational density of states activated by the disorder of the sp2 phase.Comment: 15 pages, 5 figures, 1 tabl