Density-functional study of hydrogen chemisorption on vicinal Si(001) surfaces

Relaxed atomic geometries and chemisorption energies have been calculated for the dissociative adsorption of molecular hydrogen on vicinal Si(001) surfaces. We employ density-functional theory, together with a pseudopotential for Si, and apply the generalized gradient approximation by Perdew and Wang to the exchange-correlation functional. We find the double-atomic-height rebonded D_B step, which is known to be stable on the clean surface, to remain stable on partially hydrogen-covered surfaces. The H atoms preferentially bind to the Si atoms at the rebonded step edge, with a chemisorption energy difference with respect to the terrace sites of >sim 0.1 eV. A surface with rebonded single atomic height S_A and S_B steps gives very similar results. The interaction between H-Si-Si-H mono-hydride units is shown to be unimportant for the calculation of the step-edge hydrogen-occupation. Our results confirm the interpretation and results of the recent H_2 adsorption experiments on vicinal Si surfaces by Raschke and Hoefer described in the preceding paper.Comment: 13 pages, 8 figures, submitted to Phys. Rev. B. Other related publications can be found at http://www.rz-berlin.mpg.de/th/paper.htm

Highly site-specific H2 adsorption on vicinal Si(001) surfaces

Experimental and theoretical results for the dissociative adsorption of H_2 on vicinal Si(001) surfaces are presented. Using optical second-harmonic generation, sticking probabilities at the step sites are found to exceed those on the terraces by up to six orders of magnitude. Density functional theory calculations indicate the presence of direct adsorption pathways for monohydride formation but with a dramatically lowered barrier for step adsorption due to an efficient rehybridization of dangling orbitals.Comment: 5 pages, 4 figures, submitted to Phys. Rev. Lett. (1998). Other related publications can be found at http://www.fhi-berlin.mpg.de/th/paper.htm

Effect of shape, gluten, and mastication effort on in vitro starch digestion and the predicted glycemic index of pasta

Gluten-containing (GC) and gluten-free (GF) pasta consumption has been growing in recent years. The market offers a wide variety of pasta types, with differences in shape and formulation that influence the mastication process and, consequently, their nutritional behaviors (i.e. starch digestibility and glycemic response). This study investigated the effect of shape, gluten, and structural breakdown on in vitro starch digestibility and predicted the glycemic index (pGI) of GC and GF penne, spaghetti, and risoni. Pasta was cooked and minced to mimic short, intermediate, and long mastication efforts. Short mastication led to a higher number of big particles than intermediate and long mastications for all pasta samples, which was reflected in the different starch digestibility and pGI patterns. Multivariate analysis of variance showed that the three studied factors differently affected the in vitro starch digestion of pasta. Mastication effort, shape, and their interaction mainly affected the starch digestion rate and pGI. Gluten was the major factor in affecting the amount of digested starch. The results suggested that small shapes (i.e. risoni), the presence of gluten, and short mastication effort led to a lower pGI. The findings will be useful for the development of pasta products tailored to fulfill the needs of specific consumers following a rational food design approach

Sources of Information about Dietary Fibre: A Cross-Country Survey

Dietary fibre (DF) has been recognized as a major determinant for improvement of health. Hence the means of information through which people become aware of its benefits are crucial. This work aimed at studying the sources of information about DF, as a means to educate people about aspects related to healthy eating. Factors such as gender, level of education, living environment or country were evaluated as to their effect on the selection of sources and preferences. For this, a descriptive cross-sectional study by means of a questionnaire, applied to a non-probabilistic sample of 6010 participants from 10 countries in different continents (Europe, Africa and America), answered after informed consent by all participants. For the analysis were used several descriptive statistics tools, crosstabs and chi square test to assess the relations between some of the variables under study. The results showed that mostly the information about DF comes from the internet, but the participants recognize that television might be a most suitable way to disseminate information about DF. The results also indicated differences between genders, levels of education, living environments and countries. The internet, the preferred source of information, got highest scores for Hungary, for urban areas, for university level of education and for female gender. The radio, the least scored source of information, was preferred in Egypt, for men and with lower education (primary school). As a conclusion, people get information through the internet due to easy access. However, it is to some extent a risk given the impossibility to control de information made public on the internet. The role of health centers and hospitals as well as schools should definitely be increased, as a responsible way to ensure correct information

Can fermentation methods and granulometry modulate bread starch digestibility without hindering its technological quality?

Reducing starch digestibility in bread while maintaining its quality has been a trending topic in recent decades. This study explores the effects of different fermentation methods—Direct Method (DM), Poolish (PO), and Sourdough (SD)—combined with semolina of varying granulometry (Fine Semolina (FS), ∼150 μm; Coarse Semolina (CS), ∼550 μm) on bread properties. A full factorial design was employed to assess the influence of these variables on dough properties (pH and total titratable acidity (TTA)), bread quality (porosity, texture profile analysis, and volume), and in vitro digestibility (using Englyst's method). Results indicate that SD-fermented doughs exhibited higher TTA and lower pH, leading to bread with reduced porosity and volume compared to PO and DM, and a reduced starch digestibility due to a dense crumb structure. CS produced slightly more porous bread with lower resistant starch than FS. To conclude, the fermentation method was the major factor influencing bread quality and digestibility

The role of economic news in predicting suicides

JEL classification: I14; I15.Data availability: The authors do not have permission to share data.Appendix. Brief overview of the WordNet-Affect: A synset is a group of data elements that are considered semantically equivalent for the purposes of information retrieval. WordNet-Affect is an extension of WordNet Domains (see Magnini and Cavaglià, 2000), that includes a set of synsets suitable to represent affective concepts representing moods, situations eliciting emotions, or emotional responses. The authors specifically initially identified a set of words that directly refer to emotional states (e.g. fear, cheerful, sad). Then, they expanded this initial set by implementing an unsupervised algorithm that exploited a mechanism of semantic similarity to automatically acquire from a large corpus of texts (100 millions of words). The final data set includes 1641 terms characterising 28 different emotions. Further information on the approach are available at the web link https://wndomains.fbk.eu/wnaffect.html .In this paper we explore the role of media and language used to comment on economic news in nowcasting and forecasting suicides in England and Wales. This is an interesting question, given the large delay in the release of official statistics on suicides. We use a large data set of over 200,000 news articles published in six major UK newspapers from 2001 to 2015 and carry sentiment analysis of the language used to comment on economic news. We extract daily indicators measuring a set of negative emotions that are often associated with poor mental health and use them to explain and forecast national daily suicide figures. We find that highly negative comments on the economic situation in newspaper articles are predictors of higher suicide numbers, especially when using words conveying stronger emotions of fear and despair. Our results suggest that media language carrying very strong, negative feelings is an early signal of a deterioration in a population’s mental health

Food choice determinants and perceptions of a healthy diet among Italian consumers

Healthy food choices are crucial for a healthy lifestyle. However, food choices are complex and affected by various factors. Understanding the determinant factors affecting food choices could aid policy-makers in designing better strategies to promote healthy food choices in the general public. This study aims to evaluate the food choice motivations and to segment consumer groups, according to their food choice motivations, in a sample of 531 Italian consumers (collected by convenience sampling), through offline and online survey platforms. K-means cluster analysis was applied to identify consumer groups using six food choice motivation categories (health, emotional, economic and availability, social and cultural, environmental and political, and marketing and commercial). The results suggest that the strongest determinants for the food choices of Italian consumers are Environmental factors and Health. Two consumer profiles were identified through the segmentation analysis: Emotional eating and Health-driven consumers. The respondents were found to have a good awareness of what comprises a healthy diet. There is a potential market for healthy and sustainable food products, especially products with minimal or environmentally friendly packages. Food labels and information strategies could be promoted as tools to assist consumers to make healthy food choices

Development of sugar- and fat-reduced pulse cookies with improved predicted glycemic behavior

Cookies, a trendy snack, are traditionally characterized by a poor nutritional profile (high sugars and fats, low protein and fiber). To improve their nutritional profile, standard wheat “pasta-frolla” cookies were reformulated with 100 % pulse flour (chickpea and lentil), partial sugar reduction with a commercial fiber syrup (Meltec®), and full butter replacement using a structured fiber-sunflower oil-water emulsion (alone or in conjunction). Developed cookies had higher protein and fiber contents, reduced sugar (∼45 - 50 % reduction), and saturated fats (∼77 - 80 % reduction) and also had a lower predicted glycemic index compared to traditional cookies. Water activity and moisture content of the cookies were in line with those of the same product category, while they had a harder texture compared to their full butter counterparts due to the full substitution of butter (alone or in combination with sugar reduction). Lentil cookies showed slightly lower in vitro starch and remarkably higher protein digestibility than the control cookie, and the simultaneous application of sugar and fat substitution did not negatively affect their overall acceptability. The developed products are expected to be a suitable base for the development of snacks for elderly consumers, who are the population niche that, due to health issues, is most likely to be interested in this type of cookies