Synthesis of the fatty esters of solketal and glycerol-formal: biobased specialty chemicals

The caprylic, lauric, palmitic and stearic esters of solketal and glycerol formal were synthesized with high selectivity and yields by a solvent-free acid catalyzed procedure. No acetal hydrolysis was observed notwithstanding the acidic condition

A New Method for the Techno-Economic Analysis and the Identification of Expansion Strategies of Neutral-Temperature District Heating and Cooling Systems

Neutral-temperature district heating and cooling (NT-DHC) is a recent concept in the district heating sector. The current literature does not directly address the ability to create comprehensive master plans for NT-DHC systems and reliably model their performance. This research presents a new approach for the evaluation and planning of NT-DHC systems. The methodology involves the use of a knapsack optimization algorithm to perform a comprehensive analysis of the conditions that make the NT-DHC solution competitive against individual heating and cooling technologies. The algorithm determines the optimal combination of potential extensions that maximizes overall economic value. The results of a case study, which was conducted in Italy, show that NT-DHC is more suitable in dense urban areas, while air-to-water heat pumps are better suited for low heat density zones. This methodology aims to reduce the risks associated with energy demand and provide more certainty about which areas a network can expand into to be competitive. It is targeted at energy planners, utilities experts, energy engineers, and district heating experts who require assistance and guidance in the planning and early stages of designing a NT-DHC system. This method might enable pre-feasibility studies and preliminary design to determine the opportunities and limitations of a system of this kind from an economic and technological perspective

Phosphonium salts and P-ylides

The present chapter is aimed at describing the state-of-the-art, for the period January December 2014, of two pillar classes of phosphorus-containing compounds, the phosphonium salts and ylides. Topics are organized to offer an introductory survey on the methods of preparation and characterisation of both types of compounds, followed by an analysis of the most remarkable but also curiosity driven researches for their applications. A special section is devoted to phosphonium-based ionic liquids (PILs) due to the exceptional importance of this subject

2‐formyl‐5‐(hydroxymethyl)furan (HMF) derivatives as active complexing agent for CO2 insertion reaction

Renewable-based furan compounds derived from 2-formyl-5-(hydroxymethyl)furan (5-HMF) were successfully employed as catalysts to synthesize cyclic organic carbonates through the reaction of carbon dioxide with epoxides. The effects of temperature, reaction time, reagent ratios, and carbon dioxide pressure were optimized before evaluating various bio-based complexing agents in combination with different alkali metal halide salts. Among them, 2,5-bis(hydroxymethyl)tetrahydrofuran (BHTHF) showed the highest efficiency as a complexing agent when paired with sodium bromide (NaBr), enabling the production of industrially relevant cyclic carbonates in high yields (12 examples, achieving 94-99% epoxide conversion and 70-99% carbonate selectivity) under mild pressure conditions (carbon dioxide pressure of 1-10 bar, reaction time of 6 hours, and temperature of 120 °C). Additionally, the BHTHF/NaBr catalytic system demonstrated high stability, maintaining its performance over nine consecutive epoxide additions (8 mmol each) without any loss of efficiency

Green catalytic upgrading of renewable bio-based lactones

Studies on biomass transformation into chemicals have demonstrated that some of them can be efficiently produced. Lactones are among the most interesting ones, being a key step for the synthesis of fine chemicals, solvents, and polymers. In this work, the reactivity of bio-based lactones (γ-butyro-, γ-valero-, δ-valero- and ε–capro-lactone; GBL, GVL, DVL, and ECL respectively), with dialkyl carbonates (DAlCs), has been studied, aiming to obtain higher value added chemical compounds by new greener broad-based chemical technologies. Under basic catalysis, the lactones reacted with three different DAlCs (both reactants and solvents) to yield selectively either the α-alkyl derivatives from of the five-membered ring GBL and GVL or the highly oxygenated acyclic monomeric derivatives from of the six- and seven-membered rings DVL and ECL. The ring-opening derivatives of the model lactone GVL can be obtained in conditions of acidic catalysis. The novel effect of DMC in such conditions was investigated, both in batch and continuous flow conditions. The selectivity towards methyl 4-methoxy-pentanoate or methyl pentenoate can be tuned by optimising the operating parameters

Seasonal variability of scavenger visitations is independent of carrion predictability

In temperate regions, larger mammalian carrion naturally occurs in terrestrial landscapes as a pulsed resource towards the end of the winter through enhanced ungulate mortality due to starvation or exhaustion. The return of large carnivores in Central Europe provides carrion more equally throughout the year and the active enhancement of carrion for biodiversity by game managers has increased, raising the question of how different scavengers respond to the temporal variation in carrion supply. To address this question, we experimentally deployed 106 cervid carcasses throughout the year in a temperate forest of south-eastern Germany on two types of plots: permanent (i.e., site with multiple subsequent deployments) or random (i.e., site with unique deployment), and reported vertebrate scavenger visitations by camera trapping. Deployment on random or permanent sites did not affect carrion use by any single species. Generalized additive modelling revealed that vertebrate scavenging peaked in the winter season and summer independent of carrion supply. Still, different scavenger species showed different temporal patterns. While wild boar as ungulate omnivores did not display any seasonal patterns, avian scavengers showed significant variation in visitation rates. The mesopredator red fox consumed carrion significantly more often from late winter to summer, while pine marten was present at carrion only during winter. Finally, the specialist large carnivore Eurasian lynx, visited carrion sites most frequently in late winter and early spring. Our results suggest that global warming might impact some groups of vertebrate scavengers more strongly than others by reducing carrion availability in late winter, while returning carnivores could mitigate these impacts.publishedVersio

Towards a rational design of a continuous-flow method for the acetalization of crude glycerol: scope and limitations of commercial Amberlyst 36 and AlF3·3H2O as model catalysts

The acetalization of six different types of glycerol including pure, wet, and crude-like grade compounds of compositions simulating those of crude glycerols produced by the biodiesel manufacture, was carried out with two model ketones such as acetone and 2-butanone. The reaction was investigated under continuous-flow (CF) conditions through a comparative analysis of an already known acetalization catalyst such as Amberlyst 36 (A36), and aluminum fluoride three hydrate (AlF3 center dot 3H(2)O, AF) whose use was never previously reported for the synthesis of acetals. At 10 bar and 25 degrees C, A36 was a highly active catalyst allowing good-to-excellent conversion (85%-97%) and selectivity (99%) when either pure or wet glycerol was used as a reagent. This catalyst however, proved unsuitable for the CF acetalization of crude-like glycerol (CG) since it severely and irreversibly deactivated in a few hours by the presence of low amounts of NaCl (2.5 wt %) which is a typical inorganic impurity of raw glycerol from the biorefinery. Higher temperature and pressure (up to 100 degrees C and 30 bar) were not successful to improve the outcome. By contrast, at 10 bar and 100 degrees C, AF catalyzed the acetalization of CG with both acetone and 2-butanone, yielding stable conversion and productivity up to 78% and 5.6 h(-1), respectively. A XRD analysis of fresh and used catalysts proved that the active phase was a solid solution (SS) of formula Al-2[F1-x(OH)(x)](6)(H2O)(y) present as a component of the investigated commercial AF sample. A hypothesis to explain the role of such SS phase was then formulated based on the Bronsted acidity of OH groups of the solid framework. Overall, the AF catalyst allowed not only a straightforward upgrading of CG to acetals, but also a more cost-efficient protocol avoiding the expensive refining of raw glycerol itself

Peri-Implant Behavior of Tissue Level Dental Implants with a Convergent Neck

he aim of this retrospective study was to analyze the radiographic peri-implant bone loss of bone level implants and tissue level implants with a convergent neck inscrew-retained single crowns and in screw-retained fixed partial prostheses, after two years offunctional loading.Odontologí

Divisão Sexual do Trabalho na Gestão Educacional: O perfil dos (as) Secretários (as) Estaduais de Educação no Brasil

Investigou-se o perfil dos (as) secretários (as) estaduais de educação que assumiram a função entre janeiro de 2019 a abril de 2021, sob a perspectiva da Divisão Sexual do Trabalho. Características como sexo, idade, estado civil, parentalidade, cor/raça, escolarização, experiência profissional e salários foram coletados nas mídias digitais. Aferiu-se o perfil do (as) 27 secretários (as) investigados com outros indicadores do trabalho docente e constatou-se a reprodução da divisão sexual do trabalho na função de gestão das Secretarias Estaduais de Educação, conexa a outros marcadores sociais