Sustainable Cements for Green Buildings Construction

The large amount of waste yearly disposed to landfill, the global impoverishing of natural resources and environment, the emergency of carbon dioxide emissions, are some of the motivations driving research institutes and industrial world to move towards sustainable solutions for civil engineering field. Accordingly, the use of sustainable materials for green buildings construction is an important goal that must be reached in short times. Sustainable cements can be designed by partially replacing clinker content with non hazardous waste. Indeed, recycling process can transform waste in secondary raw materials that work as new cement constituents usually leading to sustainable binders with peculiar environmental resistances. Details of cement manufacturing process and its effect on the environmental pollution as well as the route that can be carried out to tailor sustainable cements are reported and discussed

Gender Balance in Construction Material Research: The Analysis of Alkali-Activated Materials by a Bibliometric Study Using Scopus Database

Research in alkali-activated materials (AAMs) is an innovative and dynamic material science topic. This is due to the relevant performances in terms of physico-mechanical properties comparable to traditional construction materials (e.g., ordinary Portland cement). The sustainability of AAMs is often highlighted since they can be developed by using many natural or industrial by-products–based precursors. This leads to challenges with the optimization of AAM production due to their different performances, availability, and costs. However, they are flexible and locally adapted materials. The research interest in AAMs has rapidly increased in the early 2000s. In recent years, about 1,000 international articles have been published each year. This study aims at assessing the gender balance of this specific research topic to investigate the relevance of women’s participation. Author lists of the published articles were analyzed throughout the Scopus database, applying “alkali-activated material” and “geopolymers” as keywords in the titles, abstracts, and keywords search. The last 10 years (2009–2019) were taken into account. The gender of the most prolific authors was analyzed, and a focus of European authors on this topic was considered, as more than 25% of the research in AAMs have been carried out in Europe. The analysis of 5,900 publications in the last decade shows that there is currently a shift toward men in the gender balance in this specific research, and female authors only covered 22% of the most productive authors worldwide. Considering European authors, a more equal gender distribution is reached, when the first author is considered, with a concentration of women in the range of 36–56%, recorded over 1,396 articles

Microstructure and mechanical, physical and structural properties of sustainable lightweight metakaolin-based geopolymer cements and mortars employing rice husk

This work focuses on an in-depth investigation of the formation of pores in the structure of lightweight geopolymer cements and mortars using rice husk as a foaming agent. The hardener used in this study was sodium waterglass. Metakaolin was replaced by 0, 10, 20, 30 and 40 % by mass of husk and the obtained powders were used to produce lightweight geopolymer cements and mortars. The formation of pores in the lightweight geopolymer cements was monitored using X-ray diffractometry and infrared spectroscopy while those in the mortars were assessed using apparent density and compressive strength measurements, mercury intrusion porosimetry and optical and scanning electron microscopy. The values for the compressive strength and apparent density were in the ranges of 28.92\u20130.75 MPa and 1.88\u20131.70 g/cm 3 , respectively. The results indicated that the values for the compressive strength and apparent density of geopolymer mortars decreased while those of the cumulative pore volume increased with increases in the metakaolin replacement level. Stereomicroscopic and scanning electron microscopic images showed the presence of rice husk and fibres of rice husk, respectively, in the networks. It was found that rice husk can be used as a foaming agent for producing sustainable lightweight geopolymer mortars

LH supplementation of ovarian stimulation protocols influences follicular fluid steroid composition contributing to the improvement of ovarian response in poor responder women.

Abstract In this prospective study, we evaluated the steroid levels in 111 follicular fluids (FF) collected from 13 women stimulated with FSH monotherapy and 205 FF collected from 28 women stimulated with FSH + LH because of a previous history of hypo-responsiveness to FSH. Steroid levels were measured by HPLC/MS–MS and related to ovarian stimulation protocol, oocyte maturity, fertilization and quality of blastocysts, after individually tracking the fate of all retrieved oocytes. 17-Hydroxy-Progesterone, Androstenedione, Estradiol and Estrone were significantly higher in the FSH + LH protocol. Progesterone, 17-Hydroxy-Progesterone and Estradiol were more expressed in FF yielding a mature oocyte (p < 0.01) in the FSH + LH protocol. FF Progesterone concentration was correlated with the rate of normal fertilization in the FSH protocol. None of the FF steroids measured were associated with blastocyst quality and achievement of pregnancy. Our results indicate that LH supplementation in hypo-responsive women modifies ovarian steroid production, mimicking physiological production better and likely contributing to an improved ovarian response. Employing a correct methodological procedure to evaluate the relationship between FF steroid hormones and assisted reproduction outcomes, our study reveals that some steroids in single follicles may be helpful in predicting oocyte maturity and fertilization

Remote interfacial electron transfer processes on nanocrystalline TiO

The kinetic study of interfacial electron transfer in sensitized nanocrystalline semiconductor is essential to the design of molecular devices performing specific light induced functions in a microheterogeneous environment. A series of molecular assemblies performing direct and remote charge injection to the semiconductor have been discussed in the context of artificial photosynthesis. A particular attention in this article has been paid to the factors that control the interfacial electron transfer processes in nanocrystalline TiO2 films sensitized with mononuclear and polynuclear transition metal complexes

Copper Complexes as Effective Competitors for Iodine-free Electrolytes in Dye-Sensitized Solar Cells

Dye-sensitized solar cells, DSSCs, are photoelectrochemical devices well contextualized within the global commitment for the progressive increase of the percentage of electric energy produced by renewable resources. In the last decade the development of novel redox mediators alternative to the ubiquitous iodine-based electrolyte (identified as one of the principal causes of the stagnant PCE values in which the research got bogged down) has been one of the hottest topic of research. Efforts of many scientists have been catalyzed by metal complexes as promising single electron mediators characterized by an easy modulation of many electrochemical and optical features requested to ideal electron shuttles. While tris(diimine) cobalt complexes largely monopolize recent literature, our group has focused on homoleptic 1,10-phenanthroline-based copper complexes relying on the fact that their intrinsic limitations, if suitable tailored, could represent the turning point toward a new generation of electron shuttles. Starting from \u201cstructure vs activity maps\u201d correlating ligand substitutions with the electrochemical features of this class of complexes, we have proposed convenient Cu-based redox couples based on bulky 2-substituted phenanthrolines that reached efficiency higher than 6%, more than doubling the PCE of cells filled with the unique benchmark copper-based redox shuttle (12/22, in figure below) and even exceeding performance of a control I\u2013/I3\u2013-based electrolyte

The Improvement of Durability of Reinforced Concretes for Sustainable Structures: A Review on Different Approaches

The topic of sustainability of reinforced concrete structures is strictly related with their durability in aggressive environments. In particular, at equal environmental impact, the higher the durability of construction materials, the higher the sustainability. The present review deals with the possible strategies aimed at producing sustainable and durable reinforced concrete structures in different environments. It focuses on the design methodologies as well as the use of unconventional corrosion-resistant reinforcements, alternative binders to Portland cement, and innovative or traditional solutions for reinforced concrete protection and prevention against rebars corrosion such as corrosion inhibitors, coatings, self-healing techniques, and waterproofing aggregates. Analysis of the scientific literature highlights that there is no preferential way for the production of “green” concrete but that the sustainability of the building materials can only be achieved by implementing simulta-neous multiple strategies aimed at reducing environmental impact and improving both durability and performances

Affordable dye sensitizer by waste

Abstract The development of dye sensitizer is growing in line with the increasing demand for renewable energy. A research to obtain a dye sensitizer that is economical, safe, and produces a great value of DSSC efficiency is a challenge unresolved. On the other hand, the efforts for waste reduction are also intensively conducted to create better environment. In this paper, the variation of synthetic dye wastes from batik industries have been successfully applied as dye sensitizer and fabricated on DSSC cells. Congo red (1.0133%) yielded higher efficiency than rhodamine B (0.0126%), methyl orange (0.7560%), and naphthol blue black (0.0083%). The divergence of the efficiency of DSSC is very dependent upon the chromophore group owned by dye. This study has proven that the more chromophore group possessed by dye, the higher the efficiency of DSSC generated. This research concludes that the dye wastes have a bright future to be implemented as dye sensitizer on solar cells

Bis(1,10-phenanthroline) copper complexes with tailored molecular architecture: from electrochemical features to application as redox mediators in dye-sensitized solar cells

In the last few years, copper coordination compounds turned out to be effective competitors of cobalt complexes as redox mediators in the formulation of iodine-free electrolytes for dye-sensitized solar cells (DSSCs). However, the lack of a clear correlation between electrochemical signatures of copper complexes (i.e. half-wave potential and heterogeneous electron transfer rate) and photoelectrochemical performance of solar devices makes difficult the optimization of their coordination sphere. Therefore, to partially fill this gap and to elucidate the intrinsic correlation between the molecular architecture of these complexes and their electrochemical features, we prepared four Cu+/2+redox couples in which the copper center is coordinated by two 1,10-phenanthrolines bearing various substituents in position 2. These complexes were well characterized, from both electrochemical and spectroscopic point of view, and tested as electron shuttles in lab-scale photoelectrochemical cells sensitized with two efficient \ucf\u80-extended benzothiadiazole dyes. It appeared that 2-aryl-1,10-phenanthrolines effectively combine suitable optical and electrochemical properties. While a fast electron transfer kinetics generally positively affects the dye regeneration process, an optimal balance between dye regeneration efficiency, mass transport and heterogeneous electron transfer at both the counter electrode and at the TiO2interface, must be achieved in order to optimize DSSC performance. Within our series, the top performer was [Cu(2-tolyl-1,10-phenanthroline)2]+/2+which achieved a relative 20% and 15% improvement in power conversion efficiency (under 100 mW s\ue2\u88\u921simulated AM 1.5G illumination) with respect to control cells filled with [Co(bpy)3]2+/3+(bpy = 2,2\ue2\u80\ub2-bipyridine) and I\ue2\u88\u92/I3\ue2\u88\u92electrolytes, respectively