On side refrigerant measurement of heat pump seasonal performances

International audienceHeat pump systems have become very popular for space heating in the residential sector in Europe. However, there is no data available on the in situ seasonal heating performances of air-to-air heat pumps. This is due to the difficulty of measuring their thermal capacity on field over a long period. Several methods relying on air flow rate and enthalpy measurements are being considered for in-situ measurement for air-to-air heat pumps. But accuracy and reliability of these methods are still unknown. In this paper, we show the results of a method based on intrusive measurements (on the refrigerant side) adapted to the dynamic behavior. This method uses Coriolis flow meters measures for the refrigerant flow rate and for enthalpies. Results confirm that the refrigerant density measurement with a Coriolis flow meter can help to predict the refrigerant vapor quality with a satisfying accuracy if the quality is not too high. The method is validated by testing an air-to-water heat pump in laboratory and by using the water enthalpy method as a reference. The experimental results show that the method is reliable in dynamic conditions (including during the defrosting periods). This internal method can be used as a reference to check the air enthalpy method for air-to-air heat pumps

Infrastructure deficits and informal settlements in sub-Saharan Africa

Sustainable development is an imperative worldwide but metrics and data on poverty and quality of life have remained too coarse and abstract to characterize challenges adequately and guide practical progress. Nowhere is this challenge greater than in Africa, where we still know little about the spatial details of development. Here we leverage a comprehensive, high-precision dataset of building footprints to identify infrastructure deficits and infer informal settlements down to the street block level everywhere in sub-Saharan Africa. We identify a general pattern of informality with cities showing, on average, greater access to infrastructure and services than rural and peri-urban areas. We show that such patterns of informality are characterized by consistent statistical distributions reflecting uneven local development. We also show that these physical measures of informality are systematically associated with many indicators of human deprivation, which form a single principal component co-varying predictably with specific changes in street access to buildings. These results demonstrate that the localization of sustainable development is possible down to the street level at a continental scale and provide a general distributed strategy for accelerating progress in infrastructure and service expansion that taps local innovations in systematic, equitable and context-appropriate ways

3-hexen-1-ol isomers in Müller-Thurgau wines: A ''varietal'' characteristic affected by must sulfiting time

Research NoteMust sulfiting time can be responsible for differences in the (3E)/(3Z)-hexen-1-ol ratio of wines produced on a semi-industrial and industrial scale. However, as the (3E) isomer is normally higher than the (32) isomer, the ratio could be used, with some caution, as a contributing parameter to verifying the varietal origin of some wines, in particular of Müller-Thurgau. After hexanol, (3E)-hexen-1-ol seems to be the main Cb-alcohol in Müller-Thurgau wines from Trentino (Italy)

Halogen-bonded architectures of multivalent calix[4]arenes

A small family of novel halogen-bonded crystalline supramolecular architectures of calixarenes was obtained by the co-crystallization of cone (1) and 1,3-alternate tetrakis(3-iodopropargyloxy)calix[4]arene (4) as tetradentate halogen donors with different multidentate acceptors. Particularly interesting is the interpenetrated diamondoid network of 4 with DABCO, which represents the first example of a 2D network of calixarene macrocycles where halogen bonding is the key interaction for self-organization

Bartlett pear unsaturated ethyl deconoates and C9 compounds among components characterizing cv. Catalan roxo grape marc distillates

Catalan roxo marc distillates contain compounds at an unusual level in a grape derivate. The most peculiar are several unsaturated ethyl decanoates typical of Bartlett pear distillates and derived from ethyl esters found in the grape skins, some of which partially modified in the stereoisomery probably by the fermentation process. Remarkable compounds are unbranched aliphatic C-9 compounds at different oxidation state as well as ethyl nonanoate. At sensorially interesting levels methyl and ethyl salicylate and ethyl cinnamate, monoterpenols typical of floral-like varieties, vitispiranes and 4-ethylguaiacol are detected. Methyl salicylate is found in the berry as free and bound compound as several monoterpenols

Comparison of the microleakage in class II bulk-fill restorations and different filling techniques: An “in vitro study”

Objective: The aim of this study is to evaluate the microleakage at the interproximal horizontal margin in Class II restorations realized using four different types of composite resin: SDR® (Dentsply, Dentsply Sirona Italy – Piazza dell’Indipendenza, 11, 00185 Rome RM), Xtra-base® (VOCO, VOCO GmbH – 27457 Cuxhaven, Germany), Ceram-XTM (Dentsply, Dentsply Sirona Italy – Piazza dell’Indipendenza, 11, 00185 Rome RM), GrandioSO®(VOCO, VOCO GmbH – 27457 Cuxhaven, Germany). Additionally, two of these (SDR® and Xtra-base®) were used following a bulk fill technique following the producer’s instructions, while the other two (Ceram-XTM and GrandioSO®) were used following the traditional incremental technique. Methods: A total of 20 freshly extracted human teeth, either molar or premolars, were selected. They were randomly divided in four groups, one for each material: for each tooth, two Class II cavities, one mesial and one distal, were realized in order to be reconstructed with the material assigned to each tooth. In total, each group had five teeth and 10 restorations made, for a total of 40 restorations. After restoration, the teeth were covered with nail polish except for a 2mm-wide area which included the interproximal horizontal margin, and the apexes were sealed using Dyract®Seal sealer (Dentsply, Dentsply Sirona Italy – Piazza dell’Indipendenza, 11, 00185 Rome RM). The samples were then thermocycled at 55°C for 500 cycles and immersed in a solution of 0.2% Fuchsin dye for 24 hours. They were then sectioned mesiodistally and examined using an optical microscope (Leica DMS 1000) at a magnification of 20x: the microleakage was assessed by measuring the dye penetration through the floor of the restoration and scored using the Demarco scale (Demarco 2001). A Kruskal-Wallis Test and six Mann-Whitney tests were then performed to investigate whether or not the difference between the results in the different groups was statistically significant. Results: In this study, the best performance was observed in Group 2 (Xtra-base® VOCO; Bulk Fill technique) since no signs of microleakage were noticed. In Group 1 (SDR® Dentsply; Bulk Fill technique) the worst performance was observed: five samples showed no infiltration, while the other five showed a score of 2. In group 3 (Ceram-XTM Dentsply; Incremental technique.) six samples showed a score of 0, two samples a score of 1 and two samples a score of 2. In group 4 (GrandioSO®VOCO; Incremental technique) seven samples showed a score of 0, while one sample showed a score of 1 and two samples showed a score of 2. The Kruskal-Wallis test, however, did not reveal any statistically significant difference. Six different Mann-Whitney tests (one for each pair of groups, every combination possible) confirmed these results by not showing statistically significant differences between the different composites and techniques. Conclusion: Within the natural limitations of an in-vitro study, there is no statistically significant difference in terms of microleakage scores, even after thermocycling, between four different composite resins (Xtra-base® VOCO, SDR® Dentsply, Ceram-XTM Dentsply, GrandioSO®VOCO) two of which used with a bulk fill technique (Xtra-base® VOCO, SDR® Dentsply) and two with an incremental technique (Ceram-XTM Dentsply, GrandioSO®VOCO), as per the manufacturer’s instructions. These results encourage the design of clinical studies which could highlight differences between the performance of these composites through time when subjected not only to intra-oral temperature variation, but to occlusal forces, pH variations and plaque accumulation too

Study of Cathode Materials for Na-Ion Batteries: Comparison Between Machine Learning Predictions and Density Functional Theory Calculations

Energy storage technologies have experienced significant advancements in recent decades, driven by the growing demand for efficient and sustainable energy solutions. The limitations associated with lithium’s supply chain, cost, and safety concerns have prompted the exploration of alternative battery chemistries. For this reason, research to replace widespread lithium batteries with sodium-ion batteries has received more and more attention. In the present work, we report cutting-edge research, where we explored a wide range of compositions of cathode materials for Na-ion batteries by first-principles calculations using workflow chains developed within the AiiDA framework. We trained crystal graph convolutional neural networks and geometric crystal graph neural networks, and we demonstrate the ability of the machine learning algorithms to predict the formation energy of the candidate materials as calculated by the density functional theory. This materials discovery approach is disruptive and significantly faster than traditional physics-based computational methods