Preferential etching by flowing oxygen on the (100) surfaces of HPHT single-crystal diamond

Application of diamond is determined by its oxidation behaviour in some measure. Oxidation process of single-crystal diamond prepared under high pressure and high temperature has been studied by the thermal analysis, scanning electron microscope and Raman spectrometer. The result of a simultaneous thermal analysis indicates that single-crystal diamond is oxidized at ~ 818 °C at a heating rate of 5°C/min in the flowing oxygen. Based on the data of the thermal analysis at different heating rates, the activation energy is calculated by the Kissinger method. A weight loss rate increases with the rising heat treatment temperature from 600 to 800°C. After the oxidation at 800 °C, etch pits emerge on the {100} surfaces of single-crystal diamond, while the {111} surfaces are smooth. Shapes of the etch pits on the {100} surfaces are inverted pyramidal hollows, with edges direction parallel to the direction.Застосування алмазу в якійсь мірі визначається його поведінкою при окисленні. За допомогою термічного аналізу, скануючої електронної мікроскопії і спектроскопії комбінаційного розсіювання світла вивчено процес окислення монокристалічного алмазу, отриманого при високому тиску і високій температурі. Одночасний термічний аналіз показав, що монокристалічний алмаз окислюється при ~ 818 °С при швидкості нагріву 5 °С/хв в потоці кисню. На основі даних термічного аналізу при різних швидкостях нагрівання розраховано енергію активації за методом Кіссінджера. Швидкість втрати ваги зростає з підвищенням температури термообробки від 600 до 800 °C. Після окислення при температурі 800 °С ямки травлення з’являються на поверхні {100} монокристалічного алмазу, в той час як поверхні {111} гладкі. Форма ямок на поверхнях {100} – перевернуті пірамідальні западини з ребрами в напрямку паралельному .Применение алмаза в какой-то мере определяется его поведением при окислении. С помощью термического анализа, сканирующей электронной микроскопии и спектроскопии комбинационного рассеяния света изучен процесс окисления монокристаллического алмаза, полученного при высоком давлении и высокой температуре. Одновременный термический анализ показывает, что монокристаллический алмаз окисляется при ~ 818 °С при скорости нагрева 5 °С/мин в потоке кислорода. На основе данных термического анализа при различных скоростях нагрева рассчитана энергия активации по методу Киссинджера. Скорость потери веса возрастает с повышением температуры термообработки от 600 до 800 °C. После окисления при температуре 800 °С ямки травления появляются на поверхности {100} монокристаллического алмаза, в то время как поверхности {111} гладкие. Форма ямок на поверхностях {100} – перевернутые пирамидальные впадины с ребрами в направлении параллельном

A fucoidan plant drink reduces Helicobacter pylori load in the stomach: a real-world study

BACKGROUND: Helicobacter pylori (Hp) infection is highly prevalent globally and is predominantly managed by antibiotics. Recently, the anti-adhesive, antioxidant, antitoxin, immunomodulatory, anti-coagulant, and anti-infective activities of fucoidan, a polysaccharide extracted from brown seaweeds, have been widely studied, and the results showed promise. Fucoidan has the potential to be utilized in Hp eradication therapy. Our present clinical study was designed to evaluate the efficiency of Lewuyou®, a fucoidan plant drink (FPD) in eradicating Hp in humans. METHODS: This multi-center, clinical study was conducted between October 2020 and July 2021. Hp infection was confirmed by urea breath test (UBT). A total of 122 patients with confirmed Hp infection were enrolled; after exclusion of incomplete data, 85 eligible patients (37 males and 48 females aged 20–81 years) were included in the final analysis. FPD (50 mL per vial) was orally administered twice daily for a 4-week cycle, and 41 patients completed an 8-week cycle. RESULTS: No adverse event (AE) was reported in all 122 participants who had consumed FPD. The Hp eradication rate and clearance rate were 77.6% (66/85) and 20.0% (17/85), respectively, after 4 weeks of FPD consumption and 80.5% (33/41) and 26.8 (11/41) , respectively, after 8 weeks of consumption. CONCLUSIONS: The 4- and 8-week protocols of FPD consumption were safe and effective at reducing Hp load on the gastric mucosa, with Hp eradicated in the majority of participants

Characterization of alkali activated slag–fly ash blends containing nano-silica

Applying nano-technology/modifications in construction and building materials has shown inspiring results. This paper investigates the effects of nano-silica incorporation on an eco-friendly alkali activated slag–fly ash blends. The fresh behaviors, reaction kinetics, gel structure, porosity and strength of samples with different nano-silica contents and slag/fly ash ratios are analyzed. The results indicate that as the nano-silica content increases, the slump flow is significantly reduced, and the reaction process is slightly retarded according to the setting time and isothermal calorimetry results. The microstructure analysis carried out by FTIR and TG/DSC shows that the addition of nano-silica slightly increases the chemically bound water content. The main reaction product is a chain structured C-A-S-H type gel, regardless of the slag/fly ash ratio and nano-silica content. Increasing the nano-silica content up to around 2% benefits the compressive strength and contributes to a reduced porosity, but further higher nano-silica contents show a negative effect on the strength and the pore refinement becomes less significant. It is suggested that the nano-silica benefits the microstructure and strength by providing additional reactive silica source and the filler effect. Furthermore, the slag content exhibits a dominant role on setting times, early age reaction, compressive strength and porosity in this blended alkali system

Reaction kinetics, gel character and strength of ambient temperature cured alkali activated slag–fly ash blends

Room temperature cured alkali activated slag/fly ash blends have shown their advantages in field applications. Given that alkali activated materials are extraordinarily sensitive to the composition of the starting materials, identifying their influences is essential for their application. This paper focuses on the effects of two compositional factors: activator modulus (SiO2/Na2O from 1.0 to 1.8) and slag/fly ash mass ratios (between 90/10 and 50/50) on reaction kinetics, gel characters and compressive strength. The results show that when lowering the activator modulus, the early age reaction is significantly accelerated with a higher reaction intensity, and increasing the slag content also leads to an increased reaction rate, especially at low activator modulus. Regardless of the two influential factors, the main reaction products are chain structured C-A-S-H gels with similar water contents and thermal properties, and no typical N-A-S-H type gels are formed in the system. Slight differences in terminal Sisingle bondO bonds and crystallization temperature are caused by the activator modulus and slag/fly ash mass ratios, respectively. The compressive strength results show that the optimum activator modulus changes with the slag/fly ash mass ratio, and higher slag/fly ash mass ratios prefer higher activator moduli in general, while either too high or too low activator modulus has detrimental effect on strength. Understanding the reaction, gel structure and strength changes are fundamental for determining key manufacturing parameters and tailoring the properties

Assessing the porosity and shrinkage of alkali activated slag-fly ash composites designed applying a packing model

This paper addresses the fresh behaviors, gel structure, strength, porosity and drying shrinkage of alkali activated slag-fly ash composites designed by applying the modified Andreasen & Andersen model. The results show a large variation of slump flows and setting times when using different slag/fly ash ratios and activator moduli. The microstructure analyses by FTIR and TG show the gel structure remains stable after 1 d of curing, and mixes with higher slag contents and lower activator moduli show slightly higher bound water content. The main reaction product is a chain structured C-A-S-H type gel regardless of slag/fly ash ratio and activator modulus, but a slightly higher main absorption band is shown in samples with high fly ash contents. A 28-d compressive strength of about 90 N/mm2 is achieved and a higher content of slag leads to a higher strength and lower porosity in general. An optimum activator modulus of 1.4 in terms of strength is shown, while an increase of activator modulus between 1.0 and 1.8 benefits the pore structure refinement. Both slag content and activator modulus strongly affect the drying shrinkage, and using a high amount of fly ash and low activator modulus can effectively reduce the drying shrinkage

Development of alkali activated slag-fly ash mortars: mix design and performance assessment

In this paper, alkali activated slag-fly ash mortars were prepared by applying the modified Andreasen & Andersen particle packing model in order to maximize the packing of the granular solid materials. The effects of two key manufacturing factors: slag/fly ash ratio and activator modulus, on the fresh behaviors, gel structure development, compressive strength, and drying shrinkage were investigated. The results show that a large variation of slump flow can be found when different combinations of slag/fly ash ratio and activator modulus were used. The microstructure analysis carried out by FTIR and TG shows that the gel structure remains stable after 1 d of curing, mixes with higher slag content and lower activator modulus show a slightly higher bound water content. The main reaction product is a chain structured C-A-S-H type gel regardless of the slag/fly ash ratio and activator modulus, but a slightly higher main absorption band is shown in samples with high fly ash content. A higher content of slag in the slag-fly ash mix leads to a higher strength in general. An optimum activator modulus of 1.4 in terms of strength appears in all cases. Both slag content and activator modulus strongly affect the drying shrinkage, and using high amount of fly ash and low activator modulus can effectively reduce the drying shrinkage

Properties of alkali activated slag-fly ash blends with limestone addition

In this article, the effects of raw materials’ composition on fresh behavior, reaction kinetics, mechanical properties and microstructure of alkali activated slag–fly ash–limestone blends are investigated. The results indicate that, with the increasing content of fly ash and limestone, the slump flow increases. The setting times are shortened when increasing the slag content, while both fly ash and limestone show a negligible influence. The reaction process is slightly accelerated by the presence of limestone due to the extra provided nucleation sites, but the reaction process is mainly governed by the slag. The slag content exhibits a dominant role on strength in this ternary system, while for a constant slag content, the compressive strength increases with the increasing limestone content up to 30%. The microstructure analysis shows that the gel characteristics are independent of the limestone powder content. The presence of limestone in initially high Ca and Al conditions does not lead to the formation of additional crystalline phases, which is different from Portland cement systems. Both physically and chemically bound water contents are slightly increased when limestone powder is incorporated