The calcium silicate hydrate gel (C–S–H) was synthesized by the double decomposition method because of the simplicity and the quickness of the procedure. The structure of the C–S–H gels after 1 week ...and 4 weeks in contact with the formation solution was studied through micro-Raman, Fourier transformed infrared spectroscopy and
29
Si nuclear magnetic resonance. Simultaneous thermodifferential–thermogravimetric analysis and mass spectrometry (DTA/TG/MS) was used to identify the amount of calcium carbonate formed due to the reaction between the calcium and atmospheric CO
2
. With DTA/TG/MS, mass loss due to CO
2
was observed to take place at temperatures below 400 °C, unidentified to date, which might be associated with the CO
2
adsorbed on the C–S–H gel. Thus, in the TG analysis in the 300–430 °C range, both the loss of water due to the decomposition of the amorphous calcium carbonate and the loss of CO
2
adsorbed on the gel must be considered. Additionally, polymerization of the gel and a decrease in the Ca/Si ratio was observed from the samples from 1 to 4 weeks.
Concrete is one of the most fire‐resistant materials, whose resistance depends on the chemical and structural characteristics of the hydrated calcium silicate (C‐S‐H) formed in the hydration and ...hardening process. However, the structure and composition of this C‐S‐H varies with the time of hydration. The effect of the composition of the calcium silicate on the anhydrous material formed has been studied after subjecting it to an accelerated study of the effect of fire, irradiating it with a CO2 laser. Changes in the composition of C‐S‐H can lead to changes in the mechanical properties of the cement. C‐S‐H samples with different chemical composition (Ca/Si ratios 1 and 2) as well as different synthesis processes (double decomposition and hydrothermal) were studied. The crystalline phases obtained after heating were identified through micro‐Raman spectroscopy, which confirmed the formation of anhydrous calcium silicates with the same Ca/Si ratio as the initial one. In C‐S‐H gels with a Ca/Si ratio of over 1.5, stable Ca (OH)2 was formed. Scanning electron microscopy/energy dispersive X‐ray analysis analysis determined that in the process of heating with the laser, water is lost fast, generating porous structures. Such porosity is higher in materials with a lower Ca/Si ratio.
The effect of fire over the composition of the hydrated calcium silicate of cement has been studied. The crystalline phases obtained after irradiation with a CO2 laser were identified through micro‐Raman spectroscopy. Different calcium silicates have been formed as well as stable Ca(OH)2. After the process of heating with the laser, water is lost, generating porous structures.
The main component of the cement hydration, are both, the calcium silicate hydrate (C–S–H) and calcium silicate hydrate with Al (C–S(A)–H), whose composition is characterized by its calcium to ...silicon ratio (Ca/Si), which normally varies from 0.6 to 1.6. The theoretical Ca/Si ratios of the synthesized gels were compared with those of the experimental gels, which were determined by inductively coupled plasma atomic emission spectroscopy (ICP-OES). In addition, the microstructure of the gels was studied by spectroscopic techniques: infrared and Raman spectroscopy and nuclear magnetic resonance. By the double-decomposition method used in this work (1 day at 25 °C, inert atmosphere and pH = 12.3), only C–S–H and C–S(A)–H gels with a maximum Ca/Si ratio ranging from 0.8 to 1.0 were synthesized. However, the structures of the gels are slightly different as the Ca/Si ratio increases.
Calcium silicate hydrate, with and without Al has been synthetized following double decomposition method, with different Ca/Si ratio. Analyzing Ca/Si ratio of the formed compounds, indicate that C–S(A)-H with Ca/Si ratios from 0.6 to 1.1 can be formed.
Highlights
Calcium silicate hydrate, with and without aluminum, was synthesized by the double-decomposition method with different nominal Ca/Si ratio.
Ca/Si ratio ranging from 0.8 to 1.0 in the C–S–H synthesized by the double-decomposition method.
C–S(A)–H gel with Ca/Si ratio <0.6, cannot be synthesizes by the double-decomposition method.
As nominal Ca/Si ratio increases, Q
1
units increases in the C–S–H gel structure.
This study explored the viability of synthesising nanolime at ambient temperature by raising calcium solubility through the formation of complexes with dissolved sugars. Micro-Raman findings ...confirmed the formation of nanolime particles whilst the percentage of Ca(OH)
2
formed, observed to vary with synthesis conditions, was calculated with thermogravimetry. Nanoparticles were synthesised most productively (77%) in a 5% sugary solution at a temperature of 25 °C and a 4 h reaction time. The hexagonal nanoparticles synthesised ranged in size from 200 to 25 nm. Portlandite formation is related to calcium complex formation with less mannitol that sucrose needed to form similar NPs of Ca(OH)
2
. The sugary media also favoured the formation of amorphous calcium carbonate.
The calcium silicate hydrate gel (C-S-H) was synthesized by the double decomposition method because of the simplicity and the quickness of the procedure. The structure of the C-S-H gels after 1 week ...and 4 weeks in contact with the formation solution was studied through micro-Raman, Fourier transformed infrared spectroscopy and .sup.29Si nuclear magnetic resonance. Simultaneous thermodifferential-thermogravimetric analysis and mass spectrometry (DTA/TG/MS) was used to identify the amount of calcium carbonate formed due to the reaction between the calcium and atmospheric CO.sub.2. With DTA/TG/MS, mass loss due to CO.sub.2 was observed to take place at temperatures below 400 °C, unidentified to date, which might be associated with the CO.sub.2 adsorbed on the C-S-H gel. Thus, in the TG analysis in the 300-430 °C range, both the loss of water due to the decomposition of the amorphous calcium carbonate and the loss of CO.sub.2 adsorbed on the gel must be considered. Additionally, polymerization of the gel and a decrease in the Ca/Si ratio was observed from the samples from 1 to 4 weeks.
Fire-induced compositional changes lead to strength loss and even failure in cement and concrete. Calcium silicate hydrate (C–S–H) gel, the main product of cement hydration, dehydrates at 25–200 °C, ...while temperatures of 850–900 °C alter its structure. A Raman spectroscopic study of the amorphous and crystalline phases forming after CO
2
laser radiation of cement mortar showed that C–S–H dehydration yielded tricalcium silicate at higher, and dicalcium silicate at lower, temperatures. Post-radiation variations were identified in the position of the band generated by Si–O bond stretching vibrations.
Blockade of Ras activity by inhibiting its post-translational methylation catalyzed by isoprenylcysteine carboxylmethyltransferase (ICMT) has been suggested as a promising antitumor strategy. ...However, the paucity of inhibitors has precluded the clinical validation of this approach. In this work we report a potent ICMT inhibitor, compound 3 UCM-1336, IC50 = 2 μM, which is selective against the other enzymes involved in the post-translational modifications of Ras. Compound 3 significantly impairs the membrane association of the four Ras isoforms, leading to a decrease of Ras activity and to inhibition of Ras downstream signaling pathways. In addition, it induces cell death in a variety of Ras-mutated tumor cell lines and increases survival in an in vivo model of acute myeloid leukemia. Because ICMT inhibition impairs the activity of the four Ras isoforms regardless of its activating mutation, compound 3 surmounts many of the common limitations of available Ras inhibitors described so far. In addition, these results validate ICMT as a valuable target for the treatment of Ras-driven tumors.
Emotional intelligence is a determinant factor in sports performance. The present study analysed differences in total emotional intelligence and its four dimensions in 2166 Spanish athletes (25.20 ± ...10.17 years) from eight sports (volleyball, track and field, shooting, football, basketball, handball, gymnastics, and judo). A total of 1200 men and 966 women answered anonymously using a Google Forms questionnaire sent via WhatsApp about demographics and psychological variables. A Pearson correlation was conducted to assess the age–emotional intelligence relationship. An independent T-test and One-Way ANOVA were carried out to check for age differences between biological sex and sport and a One-Way ANCOVA to determine differences between sports controlled by age. Age differences were observed by sex and sport (p < 0.001). An association was found between age and emotional intelligence dimensions (p < 0.001), except for other’s emotional appraisal (p > 0.05). Judo was the sport with the highest levels of regulation of emotions, other’s emotional appraisal, use of emotion, and total emotional intelligence (p < 0.05). Generally, emotional intelligence was found to be more developed in individual sports than in team sports, except football. Consequently, psychological skills like emotional intelligence could be critical to achieving high performance, depending on the sport.
To review the existing evidence on the role of prehospital thrombolysis in patients with ST-segment elevation acute myocardial infarction (STEMI) as part of a strategy of cutting edge to reduce the ...time of coronary reperfusion and as a consequence improves both the survival and function.
We used the technique of exploration-reduction-evaluation-analysis and synthesis of related studies, with an overview of current recommendations, data from controlled clinical trials and from the national and international registries about the different strategies for STEMI reperfusion. In total, we examined 186 references on prehospital thrombolysis, 130 references in times door-treatment, 139 references in STEMI management and national and international registries as well as 135 references on rescue and primary percutaneous coronary intervention for STEMI. Finally the 48 references that were more relevant and informative were retained.
The «time» factor is crucial in the success of early reperfusion in STEMI especially if thrombolysis is applied correctly during the prehospital time. The primary percutaneous coronary intervention is contingent upon its feasibility before 120 min from the onset of symptoms. In our midst to internationally, thrombolysis continues to be a strategy with great impact on their expectations of life and function of patients. Telecommunication systems should be incorporate in real time to the priority needs of catastrophic diseases such as STEMI where life is depending on time.
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