Molecular model of geopolymers with increasing level of disorder in the atomic structure

Concrete is the most used building material on Earth, but the production of its main binding component, cement, is responsible for 8% of worldwide CO2 emissions. A greener alternative cementitious material is provided by geopolymers, which can be synthetized from calcined clays and industrial by-products. A key issue, that limits the applicability of geopolymers in the construction sector, is an insufficient understanding of the relationship between their chemistry and development of long-term properties. Reducing these uncertainties requires an integrated approach combining modelling and experimentation. The binding phase of geopolymers often consists of sodium-alumino-silicate-hydrates (N-A-S-H), obtained through the reaction of a sodium silicate solution with an alumino-silicate source. Theoretical models describe this structure at the molecular scale as “pseudo-crystalline” [1] but, the existing models, based on solely amorphous or crystalline structures, are not always in agreement with this definition and with experimental results. For this reason, a defective crystalline structure is proposed here as a baseline geopolymer cell, featuring both amorphous and crystalline attributes (Figure 1). This new structure is created by creating vacancies in a sodalite crystalline cage, which is then stress-relaxed and reorganised to achieve full polymerisation of Al and Si tetrahedra while respecting the Loewenstein\u27s principle. Results are compared with experimental data and with other simulation results for amorphous and crystalline molecular models, showing that the newly proposed structures better capture important structural features with impact on mechanical properties, reconciling experiments with the “pseudo-crystalline” model. Specifically, the comparison with the experiments addresses the effect of Si:Al molar ratio and water content on a range of structural and mechanical properties such as skeletal density, ring structure, bong-angle distribution, X-ray diffraction (Figure 1) and X-ray pair distribution function. The simulation results confirm the necessity of a defective structure able to detect both order and disorder in geopolymers experiments. The proposed defective molecular model provides a starting point for the multiscale understanding of geopolymer cements, as well as for investigating the molecular interactions between geopolymer cements and various adsorbates, e.g. for applications in environmental engineering and nuclear engineering. Please click Additional Files below to see the full abstract

Effect of biofertilizers application on soil biodiversity and litter degradation in a commercial apricot orchard

The aim of the present experiment was to determine if the supply of biofertilizers could differently stimulate the native microbiota, thus determining different patterns of organic material decomposition processes. The microbial composition of soil and litter was investigated by next generation sequencing using a metabarcoding approach. The chemical structure of the decomposing litterbags was investigated through the TG-DTA analysis and NIR spectroscopy. The study was conducted in an apricot orchard in Italy, and two different type of biofertilizers (AMF and Trichoderma spp.) were compared to unfertilized control over one year. Bacteria and fungi in soil, 162 days from litter deposition, evidenced differentiated clusters for control and both biofertilizers; on the other hand, only fungal composition of litterbags was modified as a consequence of Trichoderma spp. supply; no effect was observed in the bacterial community of litterbags. NIR and TG-DTA analysis evidenced a significant change over time of the chemical composition of litterbags with a faster degradation as a consequence of Trichoderma spp. supply testified by a higher degradation coefficient (1.9) than control (1.6) and AMF (1.7). The supply of biofertilizers partially modified the bacteria community of soil, while Trichoderma spp. Influenced the fungal community of the litter. Moreover, Trichoderma spp. Evidenced a faster and higher degradation of litter than AMF-biofertilizers, laying the foundation for an efficient use in orchard

Effects of two different blends of naturally mycotoxin-contaminated maize meal on growth and metabolic profile in replacement heifers.

The aim of this trial was to assess the effects of the administration of different combinations of mycotoxins in naturally contaminated maize grains on dairy heifer growth, blood measurements and puberty onset. A total of 35 Friesian female heifers were randomly allotted to three experimental groups from 18-21 to 42-45 weeks of age. During the 24-week experimental period (EP), heifers were fed the same diet, but with maize meal derived from three differently contaminated lots: very low contamination, as control (C); medium-low aflatoxin-contaminated (A); and mixed aflatoxin-fumonisin contaminated (A-F). At the end of the EP, they returned to a common diet without contaminated maize, and they were monitored for an additional period of 12 weeks (post-experimental period, PEP). BW, wither height, hip height, body length and heart girth were measured every 4 weeks from the beginning of EP to the end of PEP. At the same time, body condition score was evaluated and blood samples were taken from the jugular vein to be analysed for haematological, serum protein and metabolic profiles. Age at puberty was assessed by measuring weekly plasma progesterone levels from 40 to 52 weeks of age. Body growth measurements were processed both by ANOVA of average daily gain of EP and PEP separately, and by the analysis of growth curve parameters. Haematological, serum protein and metabolic profile were evaluated using a mixed model, taking into account the repeated measurements in time on each animal. Heifers' growth was delayed both in A and A-F groups during EP, as evidenced by the different linear coefficients of the BW growth curve in the three groups. Differently contaminated diets did not affect the haematological profile, so that it can be concluded that these levels of mycotoxin contamination do not determine any specific effect on haematopoiesis and immunity in growing heifers. The main blood marker of mycotoxin chronic toxicity was the γ-glutamyl transferase activity level in plasma, which appeared to be altered even after the removal of mycotoxins. During EP, plasma glucose was lower in the groups fed contaminated diet compared with C. The joint actions of an altered nutritional status and a long-lasting liver damage were probably the causes of the delay in puberty attainment in A and, particularly, in the A-F group. The results from this trial evidenced that a chronic aflatoxin-fumonisin contamination in diets of dairy heifers can determine an important delay in the reproductive career of these animals

Vaccination of Heifers with Anaflatoxin Improves the Reduction of Aflatoxin B-1 Carry Over in Milk of Lactating Dairy Cows

It was previously reported that injection of anaflatoxin B-1 (AnAFB(1)) conjugated to keyhole limpet hemocyanin (KLH), together with Freund's adjuvant, was effective in inducing in cows a long lasting titer of anti-aflatoxin B1 (AFB(1)) antibodies (Abs), cross-reacting with other aflatoxins, which were able to hinder, proportionally to their titer, the secretion of aflatoxin M-1 (AFM(1)) into the milk of cows continuously fed with AFB(1). According to anti-AFB(1) Ab titer, 50% of the vaccinated cows were recognized as high responder animals. In an attempt to prepare a more effective formulation for vaccination of cows, it was compared the immunogenicity, in Holstein Friesian heifers, of AnAFB(1) covalently conjugated to KLH or to recombinant diphtheria toxin (CRM197) molecules, and injected together with various adjuvants. This study demonstrated that injection of AnAFB(1) conjugated to KLH and mixed with complete (priming) and incomplete Freund's adjuvant (boosters), as in the previous schedule of immunization, was the most effective regimen for inducing Ab responses against AFB(1), although pre-calving administration could increase the effectiveness of vaccination, resulting in 100% high responder animals. After one booster dose at the beginning of the milk production cycle, anti-AFB(1) Ab titers were comparable to those recorded at the end of the immunization schedule, and proved to be effective in reducing significantly AFB(1) carry over, as AFM(1), from feed to milk. Pre-calving vaccination of dairy heifers with conjugated AnAFB(1), adjuvated with complete and incomplete Freund's adjuvant, may represent the most effective tool for preventing the public health hazard constituted by milk and cheese contaminated with aflatoxins

Effects of two different blends of naturally mycotoxin-contaminated maize meal on growth and metabolic profile in replacement heifers

The aim of this trial was to assess the effects of the administration of different combinations of mycotoxins in naturally contaminated maize grains on dairy heifer growth, blood measurements and puberty onset. A total of 35 Friesian female heifers were randomly allotted to three experimental groups from 18-21 to 42-45 weeks of age. During the 24-week experimental period (EP), heifers were fed the same diet, but with maize meal derived from three differently contaminated lots: very low contamination, as control (C); medium-low aflatoxin-contaminated (A); and mixed aflatoxin-fumonisin contaminated (A-F). At the end of the EP, they returned to a common diet without contaminated maize, and they were monitored for an additional period of 12 weeks (post-experimental period, PEP). BW, wither height, hip height, body length and heart girth were measured every 4 weeks from the beginning of EP to the end of PEP. At the same time, body condition score was evaluated and blood samples were taken from the jugular vein to be analysed for haematological, serum protein and metabolic profiles. Age at puberty was assessed by measuring weekly plasma progesterone levels from 40 to 52 weeks of age. Body growth measurements were processed both by ANOVA of average daily gain of EP and PEP separately, and by the analysis of growth curve parameters. Haematological, serum protein and metabolic profile were evaluated using a mixed model, taking into account the repeated measurements in time on each animal. Heifers' growth was delayed both in A and A-F groups during EP, as evidenced by the different linear coefficients of the BW growth curve in the three groups. Differently contaminated diets did not affect the haematological profile, so that it can be concluded that these levels of mycotoxin contamination do not determine any specific effect on haematopoiesis and immunity in growing heifers. The main blood marker of mycotoxin chronic toxicity was the γ-glutamyl transferase activity level in plasma, which appeared to be altered even after the removal of mycotoxins. During EP, plasma glucose was lower in the groups fed contaminated diet compared with C. The joint actions of an altered nutritional status and a long-lasting liver damage were probably the causes of the delay in puberty attainment in A and, particularly, in the A-F group. The results from this trial evidenced that a chronic aflatoxin-fumonisin contamination in diets of dairy heifers can determine an important delay in the reproductive career of these animals

Electrical anisotropy in high-Tc granular superconductors in a magnetic field

We propose an analytical model devoted to explain the anisotropy of the electrical resistance observed below the critical temperature in granular high-Tc superconductors submitted to a magnetic field H. Reported experimental results obtained on a YBCO sample show that the superconducting transition occurs in two stages, with a steep drop of the resistance at Tc and a subsequent, smoother decrease. In this second stage, the resistance versus temperature curve is strongly dependent not only on the field intensity, but also on the angle between H and the macroscopic current density j. We start from the assumption that the resistance below Tc is mainly due to the weak links between grains. In the model, weak links are thought of as flat surface elements separating adjacent grains. We calculate the probability for a weak link to undergo the transition to the resistive state as a function of the angle it makes with the external magnetic field H and the macroscopic current density j. In doing this, an important role is given to the strong nonuniformity of the local magnetic field within the specimen, due to the effect of the screening supercurrents flowing on the surface of the grains. Finally, we calculate the electrical resistance of the sample in the two cases H⊥j and H∥j. The predictions of this simple model turn out to be in reasonable agreement with reported experimental results obtained on a YBCO granular specimen

Peripapillary Microvascular and Neural Changes in Diabetes Mellitus: An OCT-Angiography Study

Purpose: To evaluate peripapillary vessel density and morphology in patients with diabetes mellitus (DM) without clinical signs of diabetic retinopathy (DR) and with mild, nonproliferative DR and to correlate with peripapillary nerve fiber layer (NFL) thickness.Methods: One hundred seventeen eyes (34 healthy controls, 54 patients with DM without DR [noDR group] and 24 patients with mild DR [DR group]) were prospectively evaluated. All subjects underwent peripapillary and macular optical coherence tomography angiography (OCT-A). Peripapillary NFL thickness was also recorded. OCT-A slab of radial peripapillary plexus (RPC) and macular superficial capillary plexus (SCP) were analysed in order to calculate perfusion density (PD) and vessel density (VD). Further an image analysis of RPC slab was performed to identify number of branches (NoB) and total branches length (tBL).Results: In peripapillary area there was a significant decrease in VD (P = 0.003), NoB (P < 0.001), and tBL (P < 0.001) in noDR group versus controls; PD values were not different among groups (P = 0.126); there was a significant decrease in average NFL thickness in DR versus controls (P = 0.008) and in the inferior quadrant in noDR group versus controls (P = 0.03); there was a significant correlation between OCT-A and NFL thickness values (\u3c1 ranging from 0.19-0.57). In macular region PD and VD were decreased only in DR group (P < 0.05).Conclusions: There are early changes in the peripapillary vessel morphology and VD of the RPC in patients with DM without DR that correlate to NFL thinning. Earlier changes in superficial vessel density are documented in the peripapillary than in the macular region. These data may confirm a coexistence of an early neuronal and microvascular damage in patients with DM without clinical signs of DR

HARMONAC - Harmonizing air conditioning inspection and audit procedures in the tertiary building sector. Energy consumption in European air conditioning systems and the air conditioning system inspection process – Final Report

Through undertaking monitoring and measurement of the energy use in 42 AC systems and their components in 8 EU Member States, HARMONAC has been able to provide an evidence based report on the Energy Conservation Opportunities (ECOs) generally available in Air Conditioning systems. These in-depth Case Studies have then compared with ECOs found from Field Trials of HARMONAC AC system inspection procedures which are based on EN15240 - the CEN Standard for AC Inspection. This comparison has enabled conclusions to be reached about how many of the ECOs that are available would be able to be identified and implemented in EU Member States as a result of the EPBD Inspection process. The project has also produced tools for use in the Inspection process, and a Teaching Package to assist in the Training of Inspectors