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1.
Materials (Basel) ; 17(7)2024 Apr 08.
Artículo en Inglés | MEDLINE | ID: mdl-38612218

RESUMEN

Replacing cement with industrial by-products is an important way to achieve carbon neutrality in the cement industry. The purpose of this study is to evaluate the effect of eggshell powder on cement hydration properties, and to evaluate its feasibility as a substitute for cement. The substitution rates of eggshell powder are 0%, 7.5%, and 15%. Studying the heat of hydration and macroscopic properties can yield the following results. First: The cumulative heat of hydration based on each gram of cementitious material falls as the eggshell powder content rises. This is a result of the eggshell powder's diluting action. However, the cumulative heat of hydration per gram of cement rises due to the nucleation effect of the eggshell powder. Second: The compressive strengths of ES0, ES7.5, and ES15 samples at 28 days of age are 54.8, 43.4, and 35.5 MPa, respectively. Eggshell powder has a greater negative impact on the compressive strength. The effect of eggshell powder on the speed and intensity of ultrasonic waves has a similar trend. Third: As the eggshell powder content increases, the resistivity gradually decreases. In addition, we also characterize the microscopic properties of the slurry with added eggshell powder. X-ray Diffraction (XRD) shows that, as the age increases from 1 day to 28 days, hemicaboaluminate transforms into monocaboaluminate. As the content of the eggshell powder increases, FTIR analysis finds a slight decrease in the content of CSH. Similarly, thermogravimetric (TG) results also show a decrease in the production of calcium hydroxide. Although the additional nucleation effect of eggshell powder promotes cement hydration and generates more portlandite, it cannot offset the loss of portlandite caused by the decrease in cement. Last: A numerical hydration model is presented for cement-eggshell powder binary blends. The parameters of the hydration model are determined based on hydration heat normalized by cement mass. Moreover, the hydration heat until 28 days is calculated using the proposed model. The strength development of all specimens and all test ages can be expressed as an exponential function of hydration heat.

2.
Materials (Basel) ; 16(19)2023 Sep 24.
Artículo en Inglés | MEDLINE | ID: mdl-37834521

RESUMEN

Blended cement is commonly used for producing sustainable concretes. This paper presents an experimental study and an optimization design of a low-CO2 quaternary binder containing calcined clay, slag, and limestone using the response surface method. First, a Box-Behnken design with three influencing factors and three levels was used for the combination design of the quaternary composite cement. The lower limit of the mineral admixtures was 0%. The upper limits of slag, calcined clay, and limestone powder were 30%, 20%, and 10%, respectively. The water-to-binder ratio (water/binder) was 0.5. Experimental works to examine workability and strength (at 3 and 28 days) were performed for the composite cement. The CO2 emissions were calculated considering binder compositions. A second-order polynomial regression was used to evaluate the experimental results. In addition, a low-CO2 optimization design was conducted for the composite cement using a composite desirability function. The objectives of the optimization design were the target 28-day strength (30, 35, 40, and 45 MPa), target workability (160 mm flow), and low CO2 emissions. The trends of the properties of optimal combinations were consistent with those in the test results. In summary, the proposed optimization design can be used for designing composite cement considering strength, workability, and ecological aspects.

3.
World J Gastroenterol ; 29(24): 3807-3824, 2023 Jun 28.
Artículo en Inglés | MEDLINE | ID: mdl-37426318

RESUMEN

BACKGROUND: Signet-ring cell carcinoma (SRCC) was previously thought to have a worse prognosis than other differentiated gastric cancer (GC), however, recent studies have shown that the prognosis of SRCC is related to pathological type. We hypothesize that patients with SRCC and with different SRCC pathological components have different probability of lymph node metastasis (LNM). AIM: To establish models to predict LNM in early GC (EGC), including early gastric SRCC. METHODS: Clinical data from EGC patients who had undergone gastrectomy at the First Affiliated Hospital of Nanjing Medical University from January 2012 to March 2022 were reviewed. The patients were divided into three groups based on type: Pure SRCC, mixed SRCC, and non-signet ring cell carcinoma (NSRC). The risk factors were identified through statistical tests using SPSS 23.0, R, and Em-powerStats software. RESULTS: A total of 1922 subjects with EGC were enrolled in this study, and included 249 SRCC patients and 1673 NSRC patients, while 278 of the patients (14.46%) presented with LNM. Multivariable analysis showed that gender, tumor size, depth of invasion, lymphovascular invasion, ulceration, and histological subtype were independent risk factors for LNM in EGC. Establishment and analysis using prediction models of EGC showed that the artificial neural network model was better than the logistic regression model in terms of sensitivity and accuracy (98.0% vs 58.1%, P = 0.034; 88.4% vs 86.8%, P < 0.001, respectively). Among the 249 SRCC patients, LNM was more common in mixed (35.06%) rather than in pure SRCC (8.42%, P < 0.001). The area under the ROC curve of the logistic regression model for LNM in SRCC was 0.760 (95%CI: 0.682-0.843), while the area under the operating characteristic curve of the internal validation set was 0.734 (95%CI: 0.643-0.826). The subgroups analysis of pure types showed that LNM was more common in patients with a tumor size > 2 cm (OR = 5.422, P = 0.038). CONCLUSION: A validated prediction model was developed to recognize the risk of LNM in EGC and early gastric SRCC, which can aid in pre-surgical decision making of the best method of treatment for patients.


Asunto(s)
Carcinoma de Células en Anillo de Sello , Metástasis Linfática , Neoplasias Gástricas , Humanos , Carcinoma de Células en Anillo de Sello/cirugía , Carcinoma de Células en Anillo de Sello/patología , Gastrectomía/métodos , Escisión del Ganglio Linfático , Ganglios Linfáticos/cirugía , Ganglios Linfáticos/patología , Metástasis Linfática/patología , Pronóstico , Estudios Retrospectivos , Factores de Riesgo , Neoplasias Gástricas/cirugía , Neoplasias Gástricas/patología
4.
Materials (Basel) ; 16(13)2023 Jun 29.
Artículo en Inglés | MEDLINE | ID: mdl-37445018

RESUMEN

The cement industry plays a significant role in global carbon emissions, accounting for approximately 8% of global anthropogenic carbon dioxide (CO2) emissions [...].

5.
Environ Sci Pollut Res Int ; 30(32): 78665-78679, 2023 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-37277586

RESUMEN

Ultra-high-performance concrete (UHPC) exhibits high compressive strength and good durability. However, owing to the dense microstructure of UHPC, carbonation curing cannot be performed to capture and sequester carbon dioxide (CO2). In this study, CO2 was added to UHPC indirectly. Gaseous CO2 was first converted into solid calcium carbonate (CaCO3) using calcium hydroxide, and the converted CaCO3 was then added to UHPC at 2, 4, and 6 wt% based on the cementitious material. The performance and sustainability of UHPC with indirect CO2 addition were investigated through macroscopic and microscopic experiments. The experimental results showed that the method used did not negatively affect the performance of UHPC. Compared with the control group, the early strength, ultrasonic velocity, and resistivity of UHPC containing solid CO2 improved to varying degrees. Microscopic experiments, such as heat of hydration and thermogravimetric analysis (TGA), demonstrated that adding captured CO2 accelerated the hydration rate of the paste. Finally, the CO2 emissions were normalized according to the compressive strength and resistivity at 28 days. The results indicated that the CO2 emissions per unit compressive strength and unit resistivity of UHPC with CO2 were lower than those of the control group.


Asunto(s)
Carbonato de Calcio , Dióxido de Carbono , Hidróxido de Calcio , Fuerza Compresiva , Calor
6.
World J Gastroenterol ; 29(20): 3133-3144, 2023 May 28.
Artículo en Inglés | MEDLINE | ID: mdl-37346155

RESUMEN

BACKGROUND: Vonoprazan (VPZ)-based regimens are an effective first-line therapy for Helicobacter pylori (H. pylori) infection. However, their value as a rescue therapy needs to be explored. AIM: To assess a VPZ-based regimen as H. pylori rescue therapy. METHODS: This prospective, single-center, clinical trial was conducted between January and August 2022. Patients with a history of H. pylori treatment failure were administered 20 mg VPZ twice daily, 750 mg amoxicillin 3 times daily, and 250 mg Saccharomyces boulardii (S. boulardii) twice daily for 14 d (14-d VAS regimen). VPZ and S. boulardii were taken before meals, while amoxicillin was taken after meals. Within 3 d after the end of eradication therapy, all patients were asked to fill in a questionnaire to assess any adverse events they may have experienced. At least 4-6 wk after the end of eradication therapy, eradication success was assessed using a 13C-urea breath test, and factors associated with eradication success were explored. RESULTS: Herein, 103 patients were assessed, and 68 patients were finally included. All included patients had 1-3 previous eradication failures. The overall eradication rates calculated using intention-to-treat and per-protocol analyses were 92.6% (63/68) and 92.3% (60/65), respectively. The eradication rate did not differ with the number of treatment failures (P = 0.433). The rates of clarithromycin, metronidazole, and levofloxacin resistance were 91.3% (21/23), 100.0% (23/23), and 60.9% (14/23), respectively. There were no cases of resistance to tetracycline, amoxicillin, or furazolidone. In 60.9% (14/23) patients, the H. pylori isolate was resistant to all 3 antibiotics (clarithromycin, metronidazole, and levofloxacin); however, eradication was achieved in 92.9% (13/14) patients. All patients showed metronidazole resistance, and had an eradication rate of 91.3% (21/23). The eradication rate was higher among patients without anxiety (96.8%) than among patients with anxiety (60.0%, P = 0.025). No severe adverse events occurred; most adverse events were mild and disappeared without intervention. Good compliance was seen in 95.6% (65/68) patients. Serological examination showed no significant changes in liver and kidney function. CONCLUSION: VAS is a safe and effective rescue therapy, with an acceptable eradication rate (> 90%), regardless of the number of prior treatment failures. Anxiety may be associated with eradication failure.


Asunto(s)
Infecciones por Helicobacter , Helicobacter pylori , Humanos , Infecciones por Helicobacter/diagnóstico , Infecciones por Helicobacter/tratamiento farmacológico , Metronidazol/efectos adversos , Claritromicina , Levofloxacino , Estudios Prospectivos , Amoxicilina/efectos adversos , Antibacterianos/efectos adversos , Quimioterapia Combinada , Inhibidores de la Bomba de Protones/efectos adversos , Resultado del Tratamiento
7.
Materials (Basel) ; 16(10)2023 May 13.
Artículo en Inglés | MEDLINE | ID: mdl-37241333

RESUMEN

There is a lack of scientific understanding of adding an oyster shell powder (OSP) to geopolymer concrete. The purpose of this study is: (1) to evaluate the high-temperature resistance of the alkali-activated slag ceramic powder (CP) mixture added with OSP at different temperatures, (2) to address the lack of application of environmentally friendly building materials, and (3) to reduce solid waste of OSP pollution and protect the environment. OSP replaces granulated blast furnace slag (GBFS) and CP at 10% and 20% (based on binder), respectively. The mixture was heated to 400.0, 600.0, and 800.0 °C after curing for 180 days. The results of the experiment are summarized as follows: (1) The thermogravimetric (TG) results indicated that the OSP20 samples produced more CASH gels than the control OSP0. (2) As the temperature increased, the compressive strength and ultrasonic pulse velocity (UPV) both decreased. (3) Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) results reveal that the mixture undergoes a phase transition at 800.0 °C, and compared with the control OSP0, OSP20 undergoes a different phase transition. (4) The size change and appearance image results indicate that the mixture with added OSP inhibits shrinkage, and calcium carbonate decomposes to produce off-white CaO. To sum up, adding OSP can effectively reduce the damage of high temperatures (800.0 °C) on the properties of alkali-activated binders.

8.
Environ Sci Pollut Res Int ; 30(4): 10613-10623, 2023 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-36083370

RESUMEN

Slag and limestone powder are common mineral admixtures to produce environmentally friendly concrete. This paper presents an optimal design method for low-carbon concrete containing slag and limestone powder that considers the influence of strength (30, 40, 50 MPa), carbonation service life (50, 100 years), and CO2 concentration of microclimate (0.04% and 0.052%). By using a genetic algorithm to determine the global optimal solution that satisfies different constraints, the optimal mixtures and decisive factors of a concrete mix can be found. The analysis results are as follows: (1) When the carbonation service life is 50 years, the durability of carbonation is the decisive factor for designing concrete with ordinary strength (30 MPa), but for medium strength (40 MPa) and high strength (50 MPa) concrete, strength is the decisive factor. (2) When carbonation service life is 100 years, for ordinary (30 MPa) and medium strength (40 MPa) concrete, carbonation durability is the decisive design factor, while for high-strength concrete (50 MPa), it is compressive strength. (3) As carbonation durability is the decisive design factor, when the CO2 concentration of microclimate increases from 0.04 to 0.052%, the real strengths of concrete increase from 44.34 to 48.53 MPa. (4) The relations between CO2 emissions and compressive strengths and between water-binder ratios and compressive strengths of the optimized concrete design were consistent with the project, which proved the effectiveness of the proposed method.


Asunto(s)
Carbonato de Calcio , Carbono , Polvos , Dióxido de Carbono , Fuerza Compresiva
9.
J Gastrointest Oncol ; 13(2): 569-580, 2022 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-35557565

RESUMEN

Background: The prognostic nutritional index (PNI) is a useful tool to evaluate nutritional status, which is associated with postoperative complications and prognosis of patients with cancer. Recent studies have shown that PNI has important predictive value for postoperative infection in cancer patients. However, the role and clinical value of PNI in infection after radical gastrectomy remains unclear. This study investigated the relationship between PNI and infection after radical surgery for gastric cancer (GC), focusing on the predictive value of PNI. Methods: A total of 1,111 patients with primary gastric cancer who underwent radical surgery in our hospital from December 2010 to December 2020 were included in this retrospective study. The demographic and clinicopathological data of all patients were acquired through hospital information system (HIS). Preoperative serum albumin (ALB) level and peripheral blood lymphocyte count were obtained for PNI calculation. We selected 812 patients by propensity score matching to reduce biases due to the different distributions of co-variables among the comparable groups. The factors influencing postoperative infection in the matched patients were explored using univariate and multivariate analyses. Results: Baseline characteristics significantly differed among patients with different PNI scores. After one-to-one matching, the clinicopathological data of the 2 groups were comparable, and 812 patients were included for further analysis. Among these patients, 101 developed infections, with an infection rate of 12.4%, which were mainly caused by gram-negative bacteria. The incidence of infection was significantly higher in the low PNI group than in the high PNI group. Univariate and multivariate analyses identified body mass index (BMI) ≥25 kg/m2 [odds ratio (OR) =2.314, P=0.004], diabetes mellitus (OR =1.827, P=0.042), PNI score <45 (OR =2.138, P=0.037), combined multi-organ resection (OR =2.946, P<0.001), operation time ≥240 minutes (OR =2.744, P=0.023), and perioperative blood transfusion (OR =2.595, P=0.025) as risk factors for infection after radical surgery for GC. Conclusions: Infection is the most common complication after radical gastrectomy for GC, and a low preoperative PNI score is a risk factor for postoperative infection.

10.
BMC Gastroenterol ; 22(1): 76, 2022 Feb 21.
Artículo en Inglés | MEDLINE | ID: mdl-35189810

RESUMEN

BACKGROUND: Accumulating studies have demonstrated that lncRNAs play vital roles in the prognosis of gastric cancer (GC); however, the prognostic value of N6-methyladenosine-related lncRNAs has not been fully reported in GC. This study aimed to construct and validate an m6A-related lncRNA pair signature (m6A-LPS) for predicting the prognosis of GC patients. METHODS: GC cohort primary data were downloaded from The Cancer Genome Atlas. We analysed the coexpression of m6A regulators and lncRNAs to identify m6A-related lncRNAs. Based on cyclical single pairing along with a 0-or-1 matrix and least absolute shrinkage and selection operator-penalized regression analyses, we constructed a novel prognostic signature of m6A-related lncRNA pairs with no dependence upon specific lncRNA expression levels. All patients were divided into high-risk and low-risk group based on the median risk score. The predictive reliability was evaluated in the testing dataset and whole dataset with receiver operating characteristic (ROC) curve analysis. Gene set enrichment analysis was used to identify potential pathways. RESULTS: Fourteen m6A-related lncRNA pairs consisting of 25 unique lncRNAs were used to construct the m6A-LPS. Kaplan-Meier analysis showed that the high-risk group had poor prognosis. The area under the curve for 5-year overall survival was 0.906, 0.827, and 0.882 in the training dataset, testing dataset, and whole dataset, respectively, meaning that the m6A-LPS was highly accurate in predicting GC patient prognosis. The m6A-LPS served as an independent prognostic factor for GC patients after adjusting for other clinical factors (p < 0.05). The m6A-LPS had more accuracy and a higher ROC value than other prognostic models for GC. Functional analysis revealed that high-risk group samples mainly showed enrichment of extracellular matrix receptor interactions and focal adhesion. Moreover, N-cadherin and vimentin, known biomarkers of epithelial-mesenchymal transition, were highly expressed in high-risk group samples. The immune infiltration analysis showed that resting dendritic cells, monocytes, and resting memory CD4 T cells were significantly positively related to the risk score. Thus, m6A-LPS reflected the infiltration of several types of immune cells. CONCLUSIONS: The signature established by pairing m6A-related lncRNAs regardless of expression levels showed high and independent clinical prediction value in GC patients.


Asunto(s)
ARN Largo no Codificante , Neoplasias Gástricas , Biomarcadores de Tumor/genética , Biomarcadores de Tumor/metabolismo , Humanos , Pronóstico , ARN Largo no Codificante/genética , ARN Largo no Codificante/metabolismo , Reproducibilidad de los Resultados , Neoplasias Gástricas/genética
11.
Polymers (Basel) ; 13(21)2021 Nov 02.
Artículo en Inglés | MEDLINE | ID: mdl-34771353

RESUMEN

This paper presents the effects of alkali-activated blast furnace slag and fly ash (AASF) paste added with waste ceramic powder (WCP) on mechanical properties, weight loss, mesoscopic cracks, reaction products, and microstructure when exposed to 300, 600, and 900 °C. Using waste ceramic powder to replace blast furnace slag and fly ash, the replacement rate was 0-20%. The samples cured at 45 °C for 28 days were heated to 300, 600, and 900 °C to determine the residual compressive strength and weight loss at the relevant temperature. We evaluated the deterioration of the paste at each temperature through mesoscopic images, ultrasonic pulse velocity (UPV), thermogravimetric analysis (TG), Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), and with a scanning electron microscope (SEM). Relevant experimental results show that: (1) with the increase in waste ceramic powder content, the compressive strength of samples at various temperatures increased, and at 300 °C, the compressive strength of all the samples reached the highest value; (2) the residual weight increased with the increase in the content of the waste ceramic powder; (3) with a further increase in temperature, all the samples produced more mesoscopic cracks; (4) at each temperature, with the rise in waste ceramic powder content, the value of the ultrasonic pulse velocity increased; (5) the TG results showed that, as the content of waste ceramic powder increased, the formation of C-A-S-H gel and hydrotalcite decreased; (6) XRD and FTIR spectra showed that, at 900 °C, the use of waste ceramic powder reduced the formation of harmful crystalline phases; (7) the SEM image showed that, at 900 °C, as the content of waste ceramic powder increased, the compactness of the sample was improved. In summary, the addition of waste ceramic powder can improve the mechanical properties of the alkali-activated paste at high temperatures, reduce the occurrence of cracks, and make the microstructure denser.

12.
Materials (Basel) ; 14(18)2021 Sep 18.
Artículo en Inglés | MEDLINE | ID: mdl-34576637

RESUMEN

In this study, the effect of biochar on the high temperature resistance of cementitious paste was investigated using multiple experimental methods. The weight loss, cracks, residual compressive strength, and ultrasonic pulse velocity (UPV) of biochar cementitious paste with 2% and 5% biochar exposed to 300, 550 and 900 °C were measured. The products and microstructures of biochar cementitious paste exposed to high temperatures were analyzed by X-ray diffraction, Fourier transform infrared spectroscopy, thermogravimetric analysis, and scanning electron microscopy. The results showed that the cracks of specimens exposed to high temperatures decreased with increasing biochar content. The addition of 2% and 5% biochar increased the residual compressive strength of the specimens exposed to 300 °C and the relative residual compressive strength at 550 °C. As the exposure temperature increased, the addition of biochar compensated for the decreasing ultrasonic pulse velocity. The addition of biochar contributed to the release of free water and bound water, and reduced the vapor pressure of the specimen. The addition of biochar did not change the types of functional groups and crystalline phases of the products of cementitious materials exposed to high temperatures. Biochar particles were difficult to observe at 900 °C in scanning electron microscopy images. In summary, because biochar has internal pores, it can improve the high-temperature resistance of cement paste.

13.
Polymers (Basel) ; 13(16)2021 Aug 22.
Artículo en Inglés | MEDLINE | ID: mdl-34451356

RESUMEN

Every year, ceramic tile factories and the iron smelting industry produce huge amounts of waste ceramic tiles and blast furnace slag (BFS), respectively. In the field of construction materials, this waste can be used as a raw material for binders, thus reducing landfill waste and mitigating environmental pollution. The purpose of this study was to mix waste ceramic powder (WCP) into BFS paste and mortar activated by sodium silicate and sodium hydroxide to study its effect on performance. BFS was partially replaced by WCP at the rate of 10-30% by weight. Some experimental studies were conducted on, for example, the fluidity, heat of hydration, compressive strength testing, ultrasonic pulse velocity (UPV), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), electrical resistivity, sulfuric acid attack, and chloride ion diffusion coefficient. Based on the results of these experiments, the conclusions are: (1) increasing the amount of waste ceramic powder in the mixture can improve the fluidity of the alkali-activated paste; (2) adding waste ceramic powder to the alkali-activated mortar can improve the resistance of the mortar to sulfuric acid; (3) adding waste ceramic powder to the alkali-activated mortar can increase the diffusion coefficient of chloride ions; (4) the early strength of alkali-activated mortar is affected by the Ca/Si ratio, while the later strength is affected by the change in the Si/Al ratio.

14.
Environ Sci Pollut Res Int ; 28(35): 48890-48904, 2021 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-33939086

RESUMEN

CO2 uptake due to carbonation is an important issue for sustainability in the concrete industry. This study presents an analysis model of CO2 uptake of slag-blended concrete considering the service stage and the recycling stage. First, a slag-blended cement hydration model is used to evaluate the content of carbonatable substances, porosity, and diffusivity. Regarding the service stage, a one-dimensional carbonation model is proposed to evaluate carbonation depth. For the recycling stage, an unreacted core model is proposed to evaluate the carbonation fraction of crushed, spherical concrete. Second, CO2 uptake in the service stage and recycling stage is determined based on the carbonated fraction, shape of the concrete element, concrete component, and exposure conditions. The total CO2 uptake ratio is determined based on the content of CO2 uptake and CO2 emissions. Third, the analysis results show that for concrete with a water-to-binder ratio of 0.3, as the slag replacement ratio increases from 0 to 50%, the total CO2 uptake ratio increases from 21.43 to 28.87%. For concrete with 50% slag as the binder, as the water-to-binder ratio increases from 0.30 to 0.35, the total CO2 uptake ratio increases from 28.87 to 30.59%. The sizes and types of the structural elements and the diameter of the crushed concrete can impact the rate of CO2 uptake, but do not modify the total CO2 uptake ratio.


Asunto(s)
Dióxido de Carbono , Acero , Dióxido de Carbono/análisis , Carbonatos , Materiales de Construcción , Residuos Industriales/análisis
15.
Materials (Basel) ; 14(6)2021 Mar 18.
Artículo en Inglés | MEDLINE | ID: mdl-33803837

RESUMEN

This study focuses on the effects of superabsorbent polymers (SAP) and belite-rich Portland cement (BPC) on the compressive strength, autogenous shrinkage (AS), and micro- and macroscopic performance of sustainable, ultra-high-performance paste (SUHPP). Several experimental studies were conducted, including compressive strength, AS, isothermal calorimetry, X-ray diffraction (XRD), thermogravimetric analysis (TGA), attenuated total reflectance (ATR)-Fourier-transform infrared spectroscopy (FTIR), ultra-sonic pulse velocity (UPV), and electrical resistivity. The following conclusions can be made based on the experimental results: (1) a small amount of SAP has a strength promotion effect during the first 3 days, while BPC can significantly improve the strength over the following 28 days. (2) SAP slows down the internal relative humidity reduction and effectively reduces the development of AS. BPC specimens show a lower AS than other specimens. The AS shows a linear relationship with the internal relative humidity. (3) Specimens with SAP possess higher cumulative hydration heat than control specimens. The slow hydration rate in the BPC effectively reduces the exothermic heat. (4) With the increase in SAP, the calcium hydroxide (CH) and combined water content increases, and SAP thus improves the effect on cement hydration. The contents of CH and combined water in BPC specimens are lower than those in the ordinary Portland cement (OPC) specimen. (5) All samples display rapid hydration of the cement in the first 3 days, with a high rate of UPV development. Strength is an exponential function of UPVs. (6) The electrical resistivity is reduced due to the increase in porosity caused by the release of water from SAP. From 3 to 28 days, BPC specimens show a greater increment in electrical resistivity than other specimens.

16.
Materials (Basel) ; 14(4)2021 Feb 03.
Artículo en Inglés | MEDLINE | ID: mdl-33546508

RESUMEN

This study clarifies the effects of pre-soaked zeolite sand as an internal curing material on the hydration, strength, autogenous shrinkage, and durability of alkali-activated slag (AAS) mortars. The liquid-to-binder ratio (L/b) of all of the AAS mortars was 0.55. Sodium hydroxide solution was used as an alkali activator and an internal curing liquid. Calcined zeolite and natural zeolite sand replaced the standard sand at 15% and 30%, respectively. The setting time, autogenous shrinkage, compressive strength, ultrasonic pulse velocity, and surface electrical resistivity were tested. The following conclusions were drawn: (1) The addition of zeolite significantly reduces the autogenous shrinkage of AAS mortar. Compared with the control group, 30% calcined zeolite reduced the autogenous shrinkage by 96.4%. Moreover, the autogenous shrinkage of the AAS mortars was noticed in two stages (a variable temperature stage and an ambient temperature stage), and the two stages split at one day of age. (2) The compressive strength of all of the specimens increased as the zeolite sand content increased, and the highest compressive strength was obtained for AAS combined with 30% natural zeolite sand. (3) Internal curing accelerated the formation of the second peak of heat flow and reduced the accumulated heat release. (4) Calcined zeolite sand delayed the setting time of the AAS mortars. (5) The addition of zeolite significantly reduced the surface electrical resistivity of the AAS mortars. In summary, zeolite sand is extremely useful as an internal curing agent to reduce autogenous shrinkage and to increase the compressive strength of AAS mortars.

17.
Materials (Basel) ; 15(1)2021 Dec 28.
Artículo en Inglés | MEDLINE | ID: mdl-35009349

RESUMEN

At present, reducing carbon emissions is an urgent problem that needs to be solved in the cement industry. This study used three mineral admixtures materials: limestone powder (0-10%), metakaolin (0-15%), and fly ash (0-30%). Binary, ternary, and quaternary pastes were prepared, and the specimens' workability, compressive strength, ultrasonic pulse speed, surface resistivity, and the heat of hydration were studied; X-ray diffraction and attenuated total reflection Fourier transform infrared tests were conducted. In addition, the influence of supplementary cementitious materials on the compressive strength and durability of the blended paste and the sustainable development of the quaternary-blended paste was analyzed. The experimental results are summarized as follows: (1) metakaolin can reduce the workability of cement paste; (2) the addition of alternative materials can promote cement hydration and help improve long-term compressive strength; (3) surface resistivity tests show that adding alternative materials can increase the value of surface resistivity; (4) the quaternary-blended paste can greatly reduce the accumulated heat of hydration; (5) increasing the amount of supplementary cementitious materials can effectively reduce carbon emissions compared with pure cement paste. In summary, the quaternary-blended paste has great advantages in terms of durability and sustainability and has good development prospects.

18.
Exp Ther Med ; 20(5): 61, 2020 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-32952651

RESUMEN

Studies have indicated that hypertension is associated with the occurrence of acute cerebral infarction (CI) in young patients (18-45 years). However, the association between CI and left ventricular diastolic (LVD) dysfunction in young patients with hypertension has rarely been reported. The purpose of the present study was to investigate the association between LVD dysfunction and acute CI in young patients with hypertension. A total of 92 patients with acute CI who had hypertension were selected as the study group (CI group) and 98 young patients with only hypertension were selected as the control group (non-CI group). Blood pressure measurements, LVD functional assessment and cerebral MRI were performed. The χ² test was used to compare the left ventricular diastolic function between the CI and non-CI groups. The results indicated that LVD function of young patients was associated with hypertension and there was a correlation between the decrease in LVD function and the occurrence of acute CI in young patients with hypertension. The incidence of acute CI was higher in patients with decreased LVD function than in those with normal LVD function. In conclusion, hypertension in the young is associated with decreased LVD function and is a risk factor for diastolic dysfunction of the left ventricle. LVD function may be an independent predictor of acute CI in young patients with hypertension and should be considered by clinicians. By predicting the risk of acute CI in young patients with hypertension, LVD testing may aid in the primary prevention of CI or guide early treatment.

19.
Food Microbiol ; 91: 103514, 2020 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-32539964

RESUMEN

Baijiu (Chinese liquor) is a type of traditional distilled alcoholic beverage produced through spontaneous solid-state fermentation with sorghum as the primary material. Material processing, including sorghum soaking, steaming and cooling which is carried out in an open environment, is an integral part of Baijiu manufacturing. However, the microbiota involved in material pretreatment and its associate with the alcoholic fermentation is unclear. This research is aimed to exploring the diversity and role of microbiota during material pretreatment of light-flavor Baijiu. Results showed that Cyanobacteria, Epicoccum, and Cladosporium predominated in the sorghum at the beginning of soaking. Lactobacillus and Pichia became the predominant bacterial and fungal genera by the end of soaking. With the dynamics of microbiota, the pH declined sharply and the categories and concentration of volatile flavors such as alcohols, esters, acids, phenols, ketones, and aldehydes increased. Correlation analysis indicated that Lactobacillus and Pichia showed positive correlation with various flavors during soaking. Furthermore, SourceTracker analysis revealed that the microbiota involved during cooling processing was an important source of the Lactobacillus during fermentation of light-flavor Baijiu. This study illustrates the role of microbiota during material pretreatment and the association with alcoholic fermentation, which contributes to reveal the mechanism of Baijiu manufacturing.


Asunto(s)
Bebidas Alcohólicas/microbiología , Manipulación de Alimentos/métodos , Microbiota , Sorghum/microbiología , Bebidas Alcohólicas/análisis , Bacterias/clasificación , Bacterias/genética , Bacterias/aislamiento & purificación , Bacterias/metabolismo , Recuento de Colonia Microbiana , Fermentación , Microbiología de Alimentos , Hongos/clasificación , Hongos/genética , Hongos/aislamiento & purificación , Hongos/metabolismo , Concentración de Iones de Hidrógeno , Microbiota/genética , Gusto , Compuestos Orgánicos Volátiles/análisis
20.
Materials (Basel) ; 13(10)2020 May 20.
Artículo en Inglés | MEDLINE | ID: mdl-32443906

RESUMEN

In this study, the carrier effect of zeolite sands in reducing the autogenous shrinkage and optimizing the microstructure of ultra-high-performance concrete (UHPC) is studied. Pre-wetted calcined zeolite sand (CZ), calcined at 500 °C for 30 min, and natural zeolite sand (NZ), with 15 wt.% and 30 wt.% in UHPC, are used to partially replace standard sands. On that basis, a series of experiments are executed on the developed UHPC, including compressive strength, autogenous shrinkage, X-ray diffraction (XRD), and isothermal calorimetry experiments. With the increase of the zeolite sand content, the autogenous shrinkage of UHPC decreases gradually. Moreover, when the added CZ content is 30 wt.% (CZ30 specimen), it is effective in reducing autogenous shrinkage. Meanwhile, at the age of 28 days, the compressive strength of CZ30 is 97% of the control group. In summary, it is possible to effectively reduce the autogenous shrinkage of UHPC containing 30 wt.% CZ, without sacrificing its mechanical properties.

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