Niobium on BEA Dealuminated Zeolite for High Selectivity Dehydration Reactions of Ethanol and Xylose into Diethyl Ether and Furfural

In this work, we investigated the role of solid-state dealumination by (NH4)2SiF6 (25% Al removal and 13% Si insertion), the impregnation of niobium (10, 18, and 25 wt. %) on dealuminated *BEA (DB) zeolite and their catalytic properties in ethanol and xylose transformations. Among all the studied catalysts, 18%Nb-DB showed increased mesoporosity and external areas. A leveling effect in the number and strength of the proposed two sites (Brønsted and Lewis) present in the catalyst (n1 = 0.24 mmol g−1, −ΔH1 = 49 kJ mol−1, and n2 = 0.20 mmol g−1, –ΔH2 = 42 kJ mol−1) in the catalyst 18%Nb-DB, might be responsible for its good activity. This catalyst presented the highest selectivity for diethyl ether, DEE (97%) with 61% conversion after 50 ethanol pulses at 230 °C (turnover number, TON DEE = 1.15). These features allowed catalytically fruitful bonding of the ethanol molecules to the neighboring sites on the channels, facilitating bimolecular ether formation through a possible SN2 mechanism. The same catalyst was active and selective for transformation of xylose at 180 °C, showing 64% conversion and 51% selectivity for furfural (TON Furfural = 24.7) using water as a green solvent.

A Social Network Analysis of the Spanish Network of Smart Cities

This paper explores the relations of centrality and hierarchy between cities and firms implementing Smart City strategies in the context of the Spanish Network of Smart Cities (RECI). While the literature has usually focused on the global dimension of cities and firms networks, exploring a national case offers interesting insights about the presence of multinational firms in these contexts and the role played by medium-sized cities in their market expansion. The analysis is based on a two-mode network of cities and firms participating in Smart City projects with the usual measures of betweenness, in-degree and closeness, as well as computing the Gini index for each of them to assess the levels of inequality. We then explore whether the structural advantages of participating in these networks have a leveling effect or rather reinforce existing hierarchies of cities. Second, we explore how firms are intertwined in Smart City projects and whether medium-sized local firms have a relevant presence. Our findings suggest these networks become a regional gateway for multinational firms to expand their presence in Smart City national markets, rather than empowering medium-sized cities and small national firms.

Looking for the islands of equality in a sea of inequality. Why did some societies in pre-industrial Europe have relatively low levels of wealth inequality?

This paper scrutinizes the insights won by recent studies in wealth inequality in pre-industrial Europe. It focuses on the regions and periods where levels of inequality were relatively low, trying to arrive at an inventory of causes of these exceptions. It discusses catastrophic events, colonization and revolution as possible causes, but argues that these only occasionally had a leveling effect, depending on the social and institutional context in which they occurred. Most clearly wealth accumulation was restricted, even by maximums on ownership, where associative organizations held a solid position, and market and state played lesser roles as coordination systems.

Catalytic properties of the metal ion variants of mandelate racemase reveal alterations in the apparent electrophilicity of the metal cofactor

The apparent electrophilicity of the metal cofactor is altered at the active site of mandelate racemase, causing a “leveling effect” of the catalytic properties of the metalloenzyme variants.

A Tale of Two Cities: Variations in Perceptions of Disaster Recovery and the Importance of Intersectionality

In this article, the author examines long-term recovery from disaster in Joplin, Missouri, and Tuscaloosa, Alabama. Tornados devastated both cities in 2011. The author asks (1) how sociohistoric contexts influenced perceptions of recovery and (2) how perceptions of recovery vary within and across social groups and geographic contexts. This research is based on fieldwork that spans 2013 to 2016, archival data, and 162 interviews. There are three main findings. First, although most White residents in both cities narrate a lasting leveling effect, people of color in both locations repudiate that claim. Second, White residents in Joplin explain their recovery in colorblind racist ways, while Tuscaloosa residents do not. Third, the author shows the ways in which social class intersects with gender and race to produce particular perspectives.