Double Phases Research Articles

Experimental and thermodynamic investigating of carbonation behavior in Alkali-activated slag-calcined clay materials with different binder constituent

Alkali-activated materials (AAMs) have gained interest as sustainable alternatives to traditional Portland cement in recent years. However, concerns still exist regarding their durability against harsh environments such as carbonation. This study presents an experimental and thermodynamic investigation into the carbonation behavior of alkali-activated slag-calcined clay (AASCC) prepared with varying activator types (sodium hydroxide, sodium silicate, sodium carbonate), slag replacement levels with calcined clay (0 %, 10 %, 20 %), and alkali concentrations represented by the solid part of activator to base material ratio (SPA/B = 0.05, 0.075, 0.1). Furthermore, Portland cement mixtures were also prepared to compare the results with AASCC mixtures. Compressive strength, capillary water absorption, and accelerated carbonation testing were conducted on paste and concrete mixtures over 28–90 days. Thermodynamic modeling accurately predicted the experimental trends, demonstrating that this is a valuable tool for simulating complex processes in AAMs. Results illustrated that AASCC paste mixtures produced with sodium hydroxide demonstrated the best carbonation resistance due to higher pore solution pH (up to 13.74), sodium and alumino-substituted calcium silicate hydrate (CNASH) gels content, and layered double hydroxide phases (Mg-Al-LDH). Increasing alkali concentration further improved durability against the carbonation process by elevating pore solution pH and CNASH content. However, replacing slag with calcined clay reduced carbonation resistance regardless of activator type, attributed to lower pore solution pH, CNASH, and Mg-Al-LDH, although higher alkali concentrations alleviated this impact. In general, the study elucidates key chemical and physical factors regarding the carbonation of these novel materials by utilizing comparative experimental investigation and thermodynamic modeling.

Advances in using seawater in slag-containing cement systems

The use of seawater as mixing water in concrete is motivated by an increasing danger of freshwater shortages. The factors restricting its use in concrete include a high risk of concrete structure degradation as well as steel reinforcement corrosion initiated by the chlorides and sulphates in seawater. The objective of this study is to evaluate the potential of ternary cementitious systems containing the substitution of a clinker constituent in cements with ground granulated blast furnace slag (GGBFS) at rate of 45 wt% and 85 wt% and zeolite (10 wt%) mixed with seawater. Moreover, the effects of alkaline activators were evaluated as a potential method to compensate the low strength of high volume slag-zeolite-cement systems containing seawater. The hydration process was evaluated by means of calorimetry, X-ray diffraction (XRD) and scanning electron microscopy (SEM), and was supplemented by the compressive strength development (2, 7, 28 days) evaluation. It was found that presence of GGBFS in seawater-mixed systems, promotes an increase in the volume of low-calcium silicate hydrate gel-like phases, which (in addition to the layered double hydroxide phases) bind the Cl-- and SO42--ions of seawater. However, at high volume replacement level (85 wt%) the accelerating effect of seawater is limited resulting in slow rate of concrete strength gain. The proposed alkaline activation, allowed the strength enhancement, but also satisfied the conditions for the complete binding of Cl-- and SO42− -ions, due to the formation of zeolite-like alkaline aluminosilicate hydrates in the resultant cement matrix. It was found that the addition of natural zeolite accelerates hydration reactions and crystallization processes in cement systems. As an outcome, due to synergistic effect of seawater and alkali-activation, the proposed ternary blend containing 5 wt% of Portland cement exhibited only 24 % lower 28 days compressive strength when compared to freshwater-mixed Portland cement (90 wt%) – zeolite (10 wt%) reference mix.

Reverse osmosis reject water management by immobilization into alkali-activated materials

Water-intensive industries face challenges due to water scarcity and pollution. In the management of these challenges, membrane processes play an important role. However, they produce significant amounts of reject waters, in which the separated salts and pollutants are concentrated. This study aims to develop a novel management concept for reject waters using alkali activation to immobilize salts in a solid phase using metakaolin, blast furnace slag (BFS), or their mixture as precursors and to create alkali-activated materials with sufficient properties to be potentially used in construction applications. Seven different waters were used to prepare the NaOH-based alkali activator solution: deionized water, three simulated seawaters with increasing salinity, and three reverse osmosis (RO) reject waters from mining or pulp and paper industries. Overall, BFS-based samples had the highest immobilization efficiency, likely due to the formation of layered double hydroxide phases (hydrotalcite, with anion exchange capacity) and hydrocalumite (chloride-containing mineral). Moreover, high-salinity water enhanced the dissolution of precursors, prolonged the setting time, and increased the compressive strength compared with nonsaline water. Thus, the obtained materials could be used in construction applications, such as backfilling material at mines where RO concentrates are commonly produced.

Gait Characteristics over the Six-minute Walk Test in Older Women of a Specific Portuguese Community: A Cross-Sectional Study.

There is limited research on the changes that can occur in the gait biomechanical parameters of older adults over long-distance walking. Thus, this study aimed to evaluate the gait characteristics of older women of a specific Portuguese community over the six-minute walk test (6MWT) along with gait spatial and temporal parameters and angular kinematics of the lower limb joints. Twenty-six older women voluntarily participated. Each woman performed the 6MWT, and during this, their spatial and temporal parameters were collected through plantar pressure data (100Hz) and angular kinematics through an inertial sensor system (100Hz). The 6MWT was divided into four intervals, and the Friedman test was used to compare them. The median age of the women was calculated, and the Mann-Whitney test was used to compare women above and below the median age value. An increase in gait speed, stance phase, and double stance phase along the intervals was observed, as well as larger angular displacements of the hip, knee, and ankle (p<0.05). Women below or above the median age value also yielded these behaviours. Gait speed, cadence, stride length, and step length were higher in women below the median age value, while stride and step duration were lower (p<0.05). Older women yielded changes in gait spatial and temporal parameters along the 6MWT, as well as larger angular displacements of the lower limb joints. Older women (compared to younger ones) yielded lower gait speed, cadence, stride length, and step length, higher stance and double stance phases, and shorter angular displacements of the lower limb joints.

Dual-Phase Structure through Selective Etching of the Double A-Element MAX Phase in Lewis Acidic Molten Salts.

Two-dimensional (2D) MXene materials with innovative properties and versatile applications have gained immense popularity among scientists. The green and environmentally friendly Lewis acid salt etching route has opened up immense possibilities for the advancement of 2D MXene materials. In this study, we precisely etched the Al element from the double A-element MAX phases Ti2(SnyAl1-y)C by employing Lewis molten salt guided by redox potentials. This approach led to the discovery of a novel Ti2SnyCClx dual-phase structure consisting of Ti2SnC and Ti2CClx. We then established that the etching of the MAX phase via Lewis acid salt is facilitated by the oxidation of M-site elements, with the MX sublayer acting as an electron transmission conduit to enable the oxidation of A-site elements. This work is dedicated to unraveling the underlying mechanisms governing the etching processes using Lewis molten salt, thereby contributing to a more profound comprehension of these innovative etching routes.

Investigating the high-temperature and self-lubricating properties of TiAlSiCN hard coating coordinated using double amorphous phases

In this work, the competitive relationship between the double amorphous phases is systematically investigated to increase the high-temperature wear resistance of the self-lubricating TiAlSiCN coating. These double amorphous phases combine the SiNx phase with high-temperature resistance and the C-related phase with a low friction coefficient. An increase in the Si content facilitates the change in the phase composition. The resultant coating exhibits an adhesion strength of 153 N, a friction coefficient of 0.24 and a hardness of 25.24 GPa upon generation of the TiAlN(C), the SiNx and the C-related phase. In this case, the TiAlSiCN coating achieves long-term self-lubrication at high temperatures with the titanium alloy friction pair. This mechanism stems from the SiNx phase replacing the portion of the easily oxidized amorphous C-related phase, which yields an enhanced high-temperature wear resistance. The cutting distance of this TiAlSiCN is 120% higher than that of the TiAlCN during the high-speed cutting of the titanium alloy. This outcome provides an effective solution for high-temperature applications of self-lubricating coatings.

Gradient Transformation of the Double Gyroid to the Double Diamond in Soft Matter.

Transitions between gyroid and diamond intercatenated double network phases occur in many types of soft matter, but to date, the structural pathway and the crystallographic relationships remain unclear. Slice and view scanning electron microscopy tomography of a diblock copolymer affords monitoring of the evolving shape of the intermaterial dividing surface, allowing structural characterization of both the majority and minority domains. Two trihedral malleable mesoatoms combine to form a single tetrahedral mesoatom in a volume additive manner while preserving network topology, as the types of loops, the number of mesoatoms in a loop, minority domain strut lengths, and directions that connect a given mesoatom to its neighbors evolve across a 150 nm wide transition zone (TZ). The [111]DD direction is coincident with the [110]DG direction so that the (111)DD and (110)DG planes define the boundaries of the TZ. Selection of the particular crystal orientations and direction and width of the transition zone is to minimize the cost of morphing the mesoatoms from one structure to the other, by maximizing like-block continuity and minimizing the variation of the surface curvature and thickness of the domains across the TZ. Such coherent continuity of the independent, intercatenated networks across the transition zone is critical for applications such as graded mechanical trusses where the pair of different networks are joined to provide different mechanical properties for adjacent grains or could serve as a nanoscale anode/cathode allowing super charging and discharging provided the networks are continuous and rigorously separate.

Preparation and thermophysical properties of medium-entropy fluorite-structured oxide of (Y0·25Zr0.25Hf0.25Ce0.25)O2−δ

A medium-entropy fluorite-structured ceramic of (Y0·25Zr0.25Hf0.25Ce0.25)O2−δ was prepared using a solid state reaction method combined with conventional sintering at 1600 °C for 10 h. This ceramic has uniform elemental distribution without impurity and segregation. The annealing experiment results show a reversible transformation between single phase and double phases in (Y0·25Zr0.25Hf0.25Ce0.25)O2−δ in 800–1600 °C. The reversible phase transformation does not display any obvious influence on the thermal expansion of this sample. The thermal expansion coefficient of (Y0·25Zr0.25Hf0.25Ce0.25)O2−δ is 12.4 × 10−6 K−1 in 100–1500 °C, higher than that of 8 wt% yttria-stabilized zirconia (8 YSZ). Furthermore, (Y0·25Zr0.25Hf0.25Ce0.25)O2−δ possesses a lower thermal conductivity (1.51 W m−1 K−1 at 900 °C) and higher oxygen barrier property compared with 8 YSZ at high temperature. The Vickers' hardness, Young's modulus and fracture toughness of (Y0·25Zr0.25Hf0.25Ce0.25)O2−δ are 10.0 GPa, 193.9 GPa and 1.93 MPa m1/2, respectively. These results demonstrate that (Y0·25Zr0.25Hf0.25Ce0.25)O2−δ can be used as a promising candidate ceramic of thermal barrier coatings.

Regulating nitrogen fraction, phasic composition and mechanical properties in (Ti0.2V0.2Nb0.2Ta0.2W0.2)(CxNy) high-entropy ceramic via carbon stoichiometry

Regulation of nitrogen content and phasic composition can be directly controlled by adjusting raw carbon allocation based on the certain cationic component in high-entropy carbide and carbonitride. By adopting this method, a series of high-entropy ceramics with the nominal composition of (Ti0.2V0.2Nb0.2Ta0.2W0.2)(CxNy) were synthesized. Within, chemical composition, phase evolution, phasic formation mechanism, mechanical performance and the strengthening mechanism were systematically probed. The matrix has undergone the evolution from double phases to single phase and then to the complex phases with the decrease of carbon and the increase of nitrogen. The monophasic carbide exhibits the best hardness (24.59 ± 1.20 GPa), and the single-phase carbonitride with 8:1 carbon-nitrogen ratio shows the best flexure strength (282.4 ± 16.2 MPa). Precipitation of (W,M)2C also contributes to the crack deflection and the fine-grain strengthening and enhances fracture toughness (for the best of 5.44 ± 0.24 MPa∙m1/2).

Gait Analysis of Hemiparetic Adult Patients with a Quadripod Cane and a Rolling Cane.

Stroke consequences include hemiparesis and difficulty walking. Several types of canes exist to overcome these alterations, but little data compares the quadripod cane and the rolling cane in hemiparetic patients. The objective of this work is twofold: to determine whether the gait speed-the most often used parameter to assess gait performance-depends on the type of cane, and to establish which spatiotemporal parameters have the most influence. Thirty-four hemiparetic patients performed 10 m walking tests at comfortable and fast speed conditions, using both canes on two different days. To objectively analyze their gait patterns, we used a tri-axial Inertial Measurement Units (IMU)-based system to record the walking signals from which we extracted the gait spatiotemporal parameters. We particularly examined the speed, stride length, and durations of stance, swing, and double support phases. The results showed that hemiparetic patients walked faster with the rolling cane during both speed conditions. These speed increases could be explained by the decrease in the stance phase duration of the affected leg, the decrease in the double support duration, and the increase in cadence. Our findings suggest that the rolling cane allows safe and faster walking.

Co-design of 'Ways of Being', a web-based experience to optimise online arts and culture for mental health in young people.

We aimed to co-design an intervention optimising the benefits of online arts and culture for mental health in young people for subsequent testing in a trial. Co-design followed the double diamond phases of design, discover, define, develop and deliver. Navigating the views of all co-designers to produce a testable resource demanded in-depth understanding, and frequent iterations in multiple modalities of the theoretical basis of the intervention, amplification of youth voice and commitment to a common goal. Co-design with a broad range of collaborators with a shared vision was valued by young co-designers and produced an effective intervention. Co-design allowed the theoretical basis to be followed and refined to create an engaging, practical and testable web experience, aiming to optimise the mental health benefits of online arts and culture for young people in a randomised controlled trial.

The nature of gait biomechanics changes with walking speed increase in patients with anterior cruciate ligament injury.

This study on gait biomechanics is based on a functional test (FT) performed at free and fast walking speeds. We investigated the pattern of changes in gait biomechanical parameters and the knee function in patients after anterior cruciate ligament (ACL) injury or its reconstruction. The study included 51 patients (33 males, 18 females) with a confirmed recent or old history of ACL tear, before or after reconstruction (26 patients). Mocap data was obtained using an inertial system. All patients were divided into three groups: 41 patients with physiological response (compensation), 6 patients with signs of decompensation, and 4 non-assessable patients. Increase in gait speed was associated with decrease in the walking cycle duration, stance and double support phases. In the compensation group, the physiological response of the knee was manifested in increased amplitudes. In the decompensation group, the amplitudes remained unchanged or decreased. In the compensation group, there were increases in the symmetrical muscle activity. The decompensation group was characterized by electromyography asymmetry. The observed universal physiological mechanism limiting the load on the damaged joint can be used for accurate assessment of the knee functional state in various periods of rehabilitation.

Local heterogeneities and order-disorder: An approach to tailor BaTi1-xZrxO3 ceramics properties

Zirconium-doped Barium Titanate with the formula, BaTi1-xZrxO3 (BZT) for 0 ≤ x ≤ 0.08 had been prepared by the modified solid-state reaction route. X-ray diffraction patterns (XRD) and structural refinement showed the formation of single and double phases for pure and Zr-substituted barium titanate, respectively. Pure barium titanate (BT) was found in the tetragonal phase. BZT-3 and BZT-5 had a mixture of tetragonal and orthorhombic phases. A mixture of orthorhombic and rhombohedral phases was present in BZT-8. The Raman analysis confirmed the existence of two oxygen octahedra of Ti and Zr for Zr-doped BT. The FESEM micrograph exhibited an increase in average grain size with Zr content. The temperature-dependent dielectric studies showed single-phase transitions for BT, two-phase transitions for BZT-3 and BZT-5, and three-phase transitions for BZT-8. XPS analysis confirmed the presence of undercoordinated Ti3+ions. The maximum dielectric constant of 5731 was obtained for BZT-3, which decreased linearly afterward. The maximum remanent polarization = 8.287 μC/cm2 was found for BZT-3. The energy storage efficiency ≥ 50.10 % makes all the compositions suitable for high energy density capacitors. Due to the presence of 90.63 % of the orthorhombic phase in BZT-5, the highest d33 = 164 pC/N was obtained. The UV–visible spectroscopy showed the signature of p-d and d-d transitions present in the ceramics due to disordering. The direct optical bandgap increased with the rise in Zr content.

The nature of crystallographic defects in noncrystalline tubular network block copolymers

Defects are symmetry breaking features within a crystal. They can be created during growth as well as by applied mechanical forces. We address point, line and surface defects in block copolymer crystals, concentrating on the structure of defects in the tubular network double gyroid and double diamond phases. Experimental results using 3D slice and view scanning electron microscopic tomographic imaging for many types of defects are presented and the nature of the structural details and symmetries are described. Often defects are considered detrimental to the properties and performance of the material, but if the mesoscale defects in 3D periodic block copolymers can be controlled, they can be utilized to achieve various advantageous such as new optical functionalities.

Interaction of layered double hydroxide phases with chloride ions

AbstractFor the sustainable transition of the construction sector, the durability of cementitious materials needs to be guaranteed. This requires a fundamental understanding of the deterioration mechanisms for example how the ingress of potentially detrimental ions affects the composition of the pore solution as well as the phase assemblage. This contribution links results from several research projects investigating the changes in layered double hydroxides (LDH) composition upon exposure to chlorides. The Cl/Al ratio in chloride‐containing AFm phases depends on the chloride concentration as well as on the pH of the liquid phase. In addition, the amount of AFm phases is affected by the pH. Another member of the LDH group, hydrotalcite (Ht), can also incorporate chloride ions into the interlayer and exhibit a similar chloride‐binding capacity as stoichiometric Friedel's salt. However, the chloride‐binding capacity of Ht also depends on the composition of the pore solution. These findings aid the fundamental understanding of chloride‐binding mechanisms of cementitious materials. This is especially important, as the pH and calcium availability in the pore solution of hydrated cement may be altered during its service life. Moreover, the results may help to accurately predict the durability performance of samples in the laboratory.

High-throughput density functional theory screening of double transition metal MXene precursors

MXenes are an emerging class of 2D materials of interest in applications ranging from energy storage to electromagnetic shielding. MXenes are synthesized by selective etching of layered bulk MAX phases into sheets of 2D MXenes. Their chemical tunability has been significantly expanded with the successful synthesis of double transition metal MXenes. While knowledge of the structure and energetics of double transition metal MAX phases is critical to designing and optimizing new MXenes, only a small subset of these materials been explored. We present a comprehensive dataset of key properties of MAX phases obtained using density functional theory within the generalized gradient approximation exchange-correlation functionals. Energetics and structure of 8,712 MAX phases have been calculated and stored in a queryable, open database hosted at nanoHUB.

Can expiratory or inspiratory contrast-enhanced computed tomography be more efficient for fast-track cannulation of the right adrenal vein in adrenal venous sampling?

This study compares the usefulness of expiratory arterial phase (EAP)-contrast-enhanced computed tomography (CT) (CECT) with that of inspiratory arterial phase (IAP)-CECT in adrenal venous sampling (AVS). Sixty-four patients who underwent AVS and CECT at the authors' hospital between April 2013 and June 2019 were included in this study. The patients were classified into the following two groups: EAP (32 patients) and IAP (32 patients) groups. The single arterial phase images were obtained at 40 seconds in the IAP group. The double arterial phase images were obtained at 40 seconds in the early arterial phase and 55 seconds in the late arterial phase in the EAP group. The authors then compared the right adrenal vein (RAV) visualization rate on the CECT, the difference between the CECT images and adrenal venograms in the localization of the RAV orifice, the cannulation time to the RAV, and the volume of contrast agent administered intraoperatively between the two groups. The rates of the RAV visualization in the EAP group were 84.4% in the early arterial phase, 93.8% in the late arterial phase, and 100% in the combined early and late arterial phases. The rate of the RAV visualization in the IAP group was 96.9%. There was no significant difference between the two groups in terms of the rate of the RAV visualization. However, there was a small difference in the location of the RAV orifice between the CECT images and adrenal venograms in the EAP group as compared with the IAP group (P < 0.001). The median time to the RAV catheterization was significantly shorter in the EAP group (27.5 minutes) than in the IAP group (35.5 minutes; P = 0.035). The rates of the RAV visualization in the EAP group were not significant between the early arterial phase, late arterial phase, and combined early and late arterial phases (P = 0.066). However, the mean volume CT dose index in the combined early and late arterial phases was significantly higher than in the early and late arterial phases (P < 0.001). The EAP-CECT is more useful for increasing the speed of the RAV cannulation due to the small difference in the localization of the RAV orifice compared to IAP-CECT. However, since EAP-CECT has double contrast arterial phases and increased radiation exposure compared to IAP-CECT, only the late arterial phase may be acceptable to reduce radiation exposure.

Tracing chirality from molecular organization to triply-periodic network assemblies: Threading biaxial twist through block copolymer gyroids

Chirality transfer from the level of molecular structure up to mesoscopic lengthscales of supramolecular morphologies is a broad and persistent theme in self-assembled soft materials, from biological to synthetic matter. Here, we analyze the mechanism of chirality transfer in a prototypical self-assembly system, block copolymers (BCPs), in particular, its impact on one of the most complex and functionally vital phases: the cubic, triply-periodic, gyroid network. Motivated by recent experimental studies, we consider a self-consistent field model of ABC* triblock copolymers possessing an end-block of chiral chain chemistry and examine the interplay between chirality at the scale of networks in alternating double network phases and the patterns of segmental order within tubular network domains. We show that while segments in gyroids exhibit twist in both polar and nematic segmental order parameters, the magnitude of net nematic twist is generically much larger than polar twist, and more surprising, reverses handedness relative to the sense of polar order as well as the sense of dihedral twist of the network. Careful analysis of the intra-domain nematic order reveals that this unique chirality transfer mechanism relies on the strongly biaxial nature of segmental order in BCP networks and relates the biaxial twist to complex patterns of frame rotation of the principal directors in the intra-domain texture. Finally, we show that this mechanism of twist reversal leads to chirality selection of alternating gyroid networks in ABC* triblocks, in the limit of very weak chirality.

Structural, microstructural, and microwave dielectric properties of (Al1-xBx)2Mo3O12 ceramics with low dielectric constant and low dielectric loss for LTCC applications

The (Al1-xBx)2Mo3O12 ceramics with double phases were prepared by solid-phase sintering method at the temperature from 725 to 800 °C for LTCC application. Through XRD pattern and Rietveld refinement analysis, it was confirmed that the (Al1-xBx)2Mo3O12 composition consists of the coexistence of double phase (the monoclinic structure of the P21/a space group and the orthorhombic structure of the Pnca space group), and the orthorhombic phase was increased with boron substitution. The microwave dielectric properties of the (Al1-xBx)2Mo3O12 ceramic series were impacted by double-phase formation (crystal structure ratio), which increases the densification and grain uniformity. With the boron substitution, the (Al1-xBx)2Mo3O12 ceramic series demonstrate outstanding microwave dielectric properties (εr = 4.04, Q × f = 35870 GHz @ 15 GHz, τƒ = 4.2 ppm/°C) with high relative density (ρrel ≈ 98.84%) and thermal conductivity κ = 0.88 W/m.K for x = 0.3 at 775 °C, indicate that it is a promising candidate for LTCC substrate material.

Gender Differences in Gait Parameters of Healthy Adult Individuals

Background and Purpose: Anatomical and biomechanical differences between male and female are also known to cause differences in gait patterns. However, the results of the studies are contradictory. Furthermore, these studies focused only on some of the spatiotemporal parameters, and pelvic movements were not analyzed. The aim of the present study is to reveal the difference in gait parameters between male and female. Methods: 44 female and 39 males were included in the study. BTS G-Walk system was used to evaluate the gait. After the accelerometer was placed, the participants were asked to walk 8 m. Spatiotemporal parameters and pelvic kinematics were recorded. Results: Given the spatiotemporal parameters, it was found that male and female were similar in terms of speed, % stride length and step length (p&gt;0.05), while gait cycle duration, stride length, swing phase and single support phases were higher in male; and stance phase, first double support phases, cadence were found to be higher in female (p0.05), while pelvic tilt total range was higher in male and obliquity total range was higher in female (p