A promising external standard method, first described by O'Connor 15, was used to determine the quantitative phase composition of a hydrating cement paste. On the basis of the data produced we can ...conclude that the method used is absolutely to be recommended for the examination of OPC pastes, since it displays many advantages in comparison to internal standard methods and other methods. No reaction of the phase alite could be detected during the initial and the induction periods of the cement hydration. Additionally it was found that the cement phases involved in the aluminate reaction (bassanite, gypsum, anhydrite and C
3A) react successively. The changes detected in the phase composition of the OPC paste could be assigned to the different periods of OPC hydration.
Background: COVID-19 has taken on pandemic proportions with growing interest in prognostic factors. Overhydration is a risk factor for mortality in several medical conditions with its role in ...COVID-19, assessed with bioelectrical impedance (BI), gaining research interest. COVID-19 affects hydration status. The aim was to determine the hydration predictive role on 90 d survival COVID-19 and to compare BI assessments with traditional measures of hydration. Methods: We studied 127 consecutive COVID-19 patients. Hydration status was estimated using a 50 kHz phase-sensitive BI and estimated, compared with clinical scores and laboratory markers to predict mortality. Results: Non-surviving COVID-19 patients had significantly higher hydration 85.2% (76.9−89.3) vs. 73.7% (73.2−82.1) and extracellular water/total body water (ECW/TBW) 0.67 (0.59−0.75) vs. 0.54 (0.48−0.61) (p = 0.001, respectively), compared to surviving. Patients in the highest hydration tertile had increased mortality (p = 0.012), Intensive Care Unit (ICU) admission (p = 0.027), COVID-19 SEIMC score (p = 0.003), and inflammation biomarkers CRP/prealbumin (p = 0.011). Multivariate analysis revealed that hydration status was associated with increased mortality. HR was 2.967 (95%CI, 1.459−6.032, p < 0.001) for hydration and 2.528 (95%CI, 1.664−3.843, p < 0.001) for ECW/TBW, which were significantly greater than traditional measures: CRP/prealbumin 3.057(95%CI, 0.906−10.308, p = 0.072) or BUN/creatinine 1.861 (95%CI, 1.375−2.520, p < 0.001). Hydration > 76.15% or ECW/TBW > 0.58 were the cut-off values predicting COVID-19 mortality with 81.3% and 93.8% sensitivity and 64 and 67.6% specificity, respectively. Hydration status offers a sensitive and specific prognostic test at admission, compared to established poor prognosis parameters. Conclusions and Relevance: Overhydration, indicated as high hydration (>76.15%) and ECW/TBW (>0.58), were significant predictors of COVID-19 mortality. These findings suggest that hydration evaluation with 50 kHz phase-sensitive BI measurements should be routinely included in the clinical assessment of COVID-19 patients at hospital admission, to identify increased mortality risk patients and assist medical care.
The effects of polymer latexes on cement hydration were investigated by the combination of isothermal calorimetry, in-situ XRD and Cryo-SEM. Two model latexes with varied amounts of anionic charges ...were used for measurements after cleaned by dialysis to remove the serum components. This study confirms that in-situ XRD technique can be successfully adapted to hydrating cementitious systems in the presences of polymer latexes to quantitatively follow evolution of mineral phases involved in cement hydration. Results show that both polymers retard aluminate reaction and depress silicate reaction, by delaying the dissolution of C3A, anhydrite and gypsum and consequently the formation of ettringite, and reducing the dissolution of C3S and the formation of C-S-H. The anionic colloidal polymers exhibit more pronounced retardation effect on aluminate reaction than on silicate reaction due to stronger electrostatic interaction between the polymer particles and the positively charged aluminate phases. The more charged latex shows stronger retardation.
Sulfoaluminate cement (SAC) is a low carbon ecological cement with good durability and is widely used in various projects. In addition, graphene nanoplates (GNPs) have excellent thermal, electrical, ...and mechanical properties and are excellent nano-filler. However, the hydration behavior of GNPs on SAC is still unclear. In this paper, the effect of GNPs on SAC hydration was investigated by isothermal calorimetry, and the hydration kinetic model and hydration kinetic equation of SAC was established, explaining the differences in cement hydration processes with and without GNPs on SAC based on a hydration kinetic model. Results indicate that the hydration exotherm of SAC mainly includes five stages: the initial stage, the induction stage, the acceleration stage, the deceleration stage, and the stable stage. The addition of GNPs promoted the hydration exotherm of SAC and accelerated the hydration reaction. Different from the hydration reaction of Portland cement, the hydration reaction of SAC is mainly a diffusion–reaction process.
Introduction: Patients of diabetes repeatedly need blood glucose measurement, which may be falsely high due to less water intake and poor hydration of the patients. Aims & Objectives: To determine ...the effect of water intake or hydration on hematocrit and blood sugar levels in patients with diabetes mellitus. Place and Duration of Study: Pathology Department and Diabetic Center of Sheikh Zayed Hospital, Rahim Yar Khan from January 2023 to July 2023. Material & Methods: It was a cross sectional study conducted in total 75 Type-1 & Type-2 diabetes patients using convenient sampling technique. 5 ml blood samples were drawn before and 20 minutes after oral hydration with 500 ml of oral water in all these patients to determine the effect on hematocrit and blood sugar levels. The data was entered and analyzed on SPSS version 23. Pre and post observations were compared using paired t-test. p-value<0.05 was taken as statistically significant. Results: The mean value for age and BSR (before and after) of study subjects was 46±11 years, 200±97 mg/dl, and 199±94 mg/dl (p=0.8) respectively. While mean value of HCT before hydration was 39±5.8% and after hydration was 38±6.4% (p=0.006). Conclusion: Oral water hydration impacted mean hematocrit values in diabetic patients, significantly lowering them whereas their mean BSR values remained unaffected.
•Capabilities of graphene reinforced concrete are reviewed.•Reinforcing mechanism is assessed for graphene in concrete.•Graphene concrete has great potential to build smart and sustainable city.•Main ...directions and barriers for future research and applications are identified.
Graphene reinforced cement composites have been continuously reported in the past years to exhibit extraordinary mechanical properties, durability and multi-functionality owing to the unique intrinsic properties possessed by pristine graphene. In this review paper, a critical and synthetical overview of recent research findings of the graphene reinforced cement composites was conducted. The review will discuss the techniques for the dispersion of graphene and the influence of graphene on rheology, hydration, microstructure, mechanical properties, autogenous shrinkage, durability, electrical and thermal properties of cement composites. The main challenges and future prospects of graphene reinforced cement composites will be discussed to provide constructive ideas and guidance to assist with relevant studies in future.
Abstract
Mononuclear nonheme iron(II) and 2‐oxoglutarate (Fe/2OG)‐dependent oxygenases and halogenases are known to catalyze a diverse set of oxidative reactions, including hydroxylation, ...halogenation, epoxidation, and desaturation in primary metabolism and natural product maturation. However, their use in abiotic transformations has mainly been limited to C−H oxidation. Herein, we show that various enzymes of this family, when reconstituted with Fe(II) or Fe(III), can catalyze Mukaiyama hydration—a redox neutral transformation. Distinct from the native reactions of the Fe/2OG enzymes, wherein oxygen atom transfer (OAT) catalyzed by an iron‐oxo species is involved, this nonnative transformation proceeds through a hydrogen atom transfer (HAT) pathway in a 2OG‐independent manner. Additionally, in contrast to conventional inorganic catalysts, wherein a dinuclear iron species is responsible for HAT, the Fe/2OG enzymes exploit a mononuclear iron center to support this reaction. Collectively, our work demonstrates that Fe/2OG enzymes have utility in catalysis beyond the current scope of catalytic oxidation.
HYDRATION - A PUBLIC HEALTH ISSUE Marin-Ştefan, Gabriela; Horhocea (Ştefan), Mihaela; Horhocea, Daniel ...
Jurnalul medical braşovean,
01/2022
1
Journal Article
Materials and Methods: A cross-sectional study was designed using 175 subjects from Brasov (Romania), divided into two groups: sedentary group and athletes. Results: Based on the responses of the ...study participants, it was observed that water is the most consumed liquid by them. The participants of the two groups felt the need to consume more water during the study and physical effort. Key-words hydration status, thirst, water, dehydration, physical activity Cuvinte cheie: statusul hidric, sete, apǎ, deshidratare, activitate fizicǎ Introducere Apa are multe roluri în organismul uman.
The most common methods for dealing with waste glass are landfilling or incineration, which cause wastage of resources. The method for preparing ultra-high-performance concrete (UHPC) by partially ...substituting cement with glass powder (GP) was herein studied in order to realize the high value treatment of waste glass. The experimental results indicated that incorporation of 5% GP brought the highest compressive strengths for UHPC, which was increased by 5.11%, compared to the control UHPC in 28 days. Furthermore, the later-stage compressive strengths for UHPC at 60 days increased continuously with incorporation of 10% and 15% GP, respectively, indicating that GP does not hinder the development of strengths. Using multiple micro testing techniques, it was indicated that, GP exhibited pozzolanic reaction and dilution effect, which can enhance cement hydration and increased the amount of hydration products. Thus, the microstructure of UHPC with appropriate amount of GP was significantly improved. In addition, the CO 2 emissions and production costs for UHPC decreased steadily with increased GP content. Compared to the control UHPC, UHPC with 15% GP exhibited decreased by 1.47% in production costs and 7.39% in CO 2 emissions.
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•Hydration numbers of peptides and PILs obtained agrees well with other methods.•Hydration spectra reveal different water species with characteristic H–bonding.•Kosmotropic effect is ...observed for both the PILs and peptides in aqueous medium.•Effect of PILs on peptide hydration probed using differential hydration analysis.•Hydrophobicity and cooperative H-bonds decide hydration of peptides-PILs complex.
The structure of water, especially around the solute is thought to play an important role in many biological and chemical processes. Water-peptide and cosolvent-peptide interactions are crucial in determining the structure and function of protein molecules. In this work, we present the H-bonding analysis for model peptides like glycyl-glycine (gly-gly), glycine-ւ-valine (gly-val), glycyl-ւ-leucine (gly-leu) and triglycine (trigly) and triethylammonium based carboxylate protic ionic liquids (PILs) in aqueous solutions as well as for peptides in ∼0.2 mol·L−1 of aqueous PIL solutions in the spectral range of 7800–5500 cm−1 using Fourier transform near-infrared (FT-NIR) spectroscopy at 298.15 K. The hydration numbers for peptides and PILs were obtained using NIR method of simultaneous estimation of hydration spectrum and hydration number of a solute dissolved in water. The H-bond of water molecules around peptides and PILs are found to be stronger and shorter than those in pure liquid water. We observe that the hydration shell around zwitterions is a clathrate-like cluster of water in which ions entrap. Watery network analysis confirms that singly H-bonded species or NHBs changes to partial or distorted ice-like structures of water in the hydration shell of PILs. The overall water H-bonding in the hydration sphere of PILs increases in the order TEAF < TEAA < TEAG < TEAPy ≈ TEAP < TEAB. The influence of PILs on hydration behavior of peptides is explored in terms of H-bonding, cooperativity, hydrophobicity, water structural changes, ionic interactions etc.
