Composition Region Research Articles

Compositional optimization for enhanced oxidation resistance of high-entropy carbide ceramics

Excellent oxidation resistance is essential for the viability of high-entropy carbides (HECs) in high-temperature environments. However, the vast HEC compositional space presents a significant challenge in developing desirable formulations with improved oxidation tolerance. In this work, we establish a computational framework to guide the optimization of oxidation-tolerant HEC compositions and further validate the theoretical predictions through systematic oxidation experiments. Leveraging first-principles calculations, we initially determine the heterogeneous oxygen adsorption ability of different constituent elements in HECs, which is subsequently harnessed to regulate preferential oxidation and suppress the formation of detrimental oxides during the oxidation process. Incorporating this fundamental-level understanding, multi-objective optimization (MOO) was performed to identify a compositional region with potentially intrinsic oxidation immunity, achieving a balance between the compactness of the oxidation product and the thermodynamic stability of the HEC matrix. Based on our analysis, we propose a compositional design strategy involving the strategic reduction of elements with higher oxygen adsorption energies, such as Nb, Ta, and Ti in (NbTaZrHfTi)C, to effectively improve the oxidation performance of HECs. The theoretical findings are robustly corroborated by our comparative oxidation experiments, which demonstrate that the selected NbTa-depletion HEC exhibits superior antioxidant performance compared to the equiatomic counterpart. The integrated computational-experimental approach presented in this work serves as a powerful framework to accelerate the discovery and development of oxidation-resistant HECs, paving the way for their expanded applications in demanding high-temperature, oxygen-rich environments.

Composition-dependent diffusion and viscosity behavior in liquid Ti–Al–Ni ternary alloys

We conducted ab initio molecular dynamics simulations to investigate the dynamic properties of the liquid Ti–Al–Ni ternary alloy system at 2033 K. Through simulations across the entire composition range, we revealed the complex compositional dependence of self-diffusion coefficients and viscosity. The self-diffusion coefficients of Ti, Al, and Ni exhibit nonlinear distribution characteristics, while viscosity shows non-monotonic compositional dependence, with lower viscosity in Al-rich regions and higher viscosity in Ni-rich regions. To understand the structural origins of these behaviors, we analyzed chemical short-range order and local fivefold symmetry structures using Warren-Cowley parameters and fivefold symmetry parameters, uncovering a close correlation between atomic-scale structural features and dynamic properties. Evaluation of the Stokes-Einstein relation revealed varying degrees of deviation from its predicted viscosity values across composition regions. We observed a negative correlation between free volume fraction and viscosity, with varying strengths in different regions. These findings provide new perspectives for understanding the complex dynamic properties of Ti–Al–Ni liquid alloys.

Measurement of the fractional radiation length of a pixel module for the CMS Phase-2 upgrade via the multiple scattering of positrons

High-luminosity particle collider experiments such as the ones planned at the High-Luminosity Large Hadron Collider require ever-greater vertexing precision of the tracking detectors, necessitating reductions in the material budget of the detectors. Traditionally, the fractional radiation length (x/X 0) of detectors is either estimated using known properties of the constituent materials, or measured in dedicated runs of the final detector. In this paper, we present a method of direct measurement of the material budget of a CMS prototype module designed for the Phase-2 upgrade of the CMS detector using a 40–65 MeV positron beam. A total of 630 million events were collected at the Paul Scherrer Institut PiE1 experimental area using a three-plane telescope consisting of the prototype module as the central plane, surrounded by two MALTA monolithic pixel detectors. Fractional radiation lengths were extracted from scattering angle distributions using the Highland approximation for multiple scattering. A statistical technique recovered runs suffering from trigger desynchronisation, and several corrections were introduced to compensate for local inefficiencies related to geometric and beam shape constraints. Two regions of the module were surveyed and yielded average x/X 0 values of (0.72 ± 0.05)% and (0.95 ± 0.09)%, which are compatible with empirical estimates for these regions computed from known material properties of 0.753% and 0.892%, respectively. Two types of higher-granularity maps of the fractional radiation length were produced, subdivided either into rectangular regions of uniform size, or polygonal-shaped regions of uniform material composition. The results bode well for the CMS Phase-2 upgrade modules, which will play a key role in the minimisation of the material of the upgraded detector.

Intraspecies mitogenomic variation in the Black-throated Tit (Aegithalos concinnus): conserved structure, concerted evolution of duplicate control regions and multiple distinct evolutionary lineages

The mitochondrial genome is a prominent research topic due to its indispensable role in organisms and its application in many research disciplines. However, few studies have investigated intraspecies mitogenomic variation. In this study, 69 mitogenomes of the Black-throated Tit (Aegithalos concinnus) were assembled and annotated from a large number of short reads generated using high-throughput sequencing technology. Comparative analyses revealed that mitogenomic characteristics such as length, gene and nucleotide composition, codon usage, and duplicated control regions were relatively conserved despite substantial intraspecies morphological changes. Yet, all the individuals from the subspecies A. c. iredalei had one more nucleotide in the 12S rRNA than the other studied subspecies. Phylogenetic analyses showed five distinct lineages based on the complete mitogenomes and the 13 combined protein-coding genes, whereas only four lineages were observed when using the duplicate control regions. Most interestingly, each lineage had both copies of the control regions of the comprising individuals, indicating that the paralogous control regions were more similar than the orthologous sequences from the distinct lineages. This suggested the control regions had undergone concerted evolution. The Black-throated Tit has complex evolutionary history and needs further investigating the taxonomic status of these lineages, as well as the underlying evolutionary processes. Our findings call for more research on intraspecies mitogenomic variation.

Optimization of pyroelectric figure of merit of PNN-PZ-PT composition at morphotropic phase boundary

Ternary compounds are proven to be a more fascinating, owing to their potential to span a broader composition region of morphotropic phase boundary (MPB) – enhanced piezoelectric, electrostrictive, dielectric and ferroelectric properties. To activate defects dipoles, we perform MnO2 doping in ternary MPB compound 0.55Pb(Ni1/3Nb2/3)O3-0.135PbZrO3-0.315PbTiO3 [PNN-PZ-PT]. Temperature dependent dielectric spectroscopy reveals relaxor-ferroelectric nature of the synthesized ceramics. With the poling treatment, P-E loop of xMn-PNN-PZ-PT is softened, which emphasizes that the poling introduces higher order structural instability in MPB structure. The evolution of structural instability is as evidenced by the emergence of additional anomaly in thermal profile of dielectric constant due to electrical poling of xMn-PNN-PZ-PT and no systematic difference between polarizing behaviour of poled and unpoled specimen (Arrott plots). In association with defects dipoles, pyroelectric response based figure of merits (FOMs) of PNN-PZ-PT are improved. FOMs are characteristics of pyroelectric materials that insights about their suitability for specific application. Fi is suppressed with MnO2 doping and Fv, Fe and increases with MnO2 doping. Our study reveals that tailored and precise acceptor doping is crucial for the simultaneous optimization of all pyroelectric FOMs.

Kinetics of Low Molecular Substances Sorption by the Polymer Mixtures

The sorption capacity of polymer blends was analyzed on the basis of absorption kinetics. The study was carried out in an adsorption-active medium with different degrees of deformation. Heptane and butanol were used as adsorption-active media. The influence of the chemical nature of the adsorbate on the sorption process was studied. The free volume fractions for each sample of the composition were calculated. The ability of materials to absorb different amounts of substances allows us to identify the behavior peculiarities of the interfacial regions of different chemical compositions.

Desıgn of quantum-dot semiconductor optical amplifiers wıth near-zero linewidth enhancement factor

The linewidth enhancement factor (LWEF) of a semiconductor optical amplifier (SOA) quantifies refractive index fluctuations in the gain medium, which induce phase distortion in the amplified optical signal. Optoelectronic systems employing SOAs with high LWEFs often exhibit poor device stability and beam coherence. Thus, designing SOAs with low LWEF is imperative. Recently, Quantum-Dot (QD) SOAs have emerged as a solution for LWEF suppression due to quantum-confinement effects enabling tunability of the QD carrier density and emission frequency. In this study, we aim to design a composite active region comprised of a host medium and the embodied QDs, to explore the corresponding LWEF variation and propose the ultimate design strategy to achieve near-zero LWEF in QD SOAs for enhancing device stability and beam coherence. Our approach entails modeling the refractive index of the composite active region using effective medium approximation via Maxwell–Garnett mixing formulation. We then extensively tune key SOA parameters, including QD carrier density, QD emission frequency, and the collision-time constant of the carriers to uncover the optimal configuration for minimizing the LWEF. Based on empirical values, we have developed and validated a simple yet effective algorithm that precisely simulates LWEF behavior in response to changes in key QD SOA parameters. This approach offers a straightforward model for estimating LWEF variation, and its corresponding minimization in QD SOAs without requiring complex experimental measurement techniques.

HIGH-TEMPERATURE PHASE TRANSFORMATIONS IN THE COMPOSITION “KAOLIN-DOLOMITE-ALUMINA”

The article presents the results of a study of phase transformations in sintered compositions “kaolin-dolomite-alumina”. It has been established that the nature of the location of melting isotherms on the triple diagram indicates the spread of neoformation processes into the region of the internal compositions of the triangle and the formation of crystalline phases of the mineral’s spinel, corundum, mullite. It is shown that based on alumina-containing waste and kaolin, as well as partially introduced dolomite, it is possible to develop compositions of low-temperature sintering ceramic masses for technical materials.

A Comprehensive Accounting of Carbon Emissions and Carbon Sinks of China’s Agricultural Sector

Comprehensive accounting of carbon emissions and carbon sinks in the agricultural sector is crucial for China to achieve its carbon neutrality goal as early as possible. This paper develops a comprehensive and scientific accounting system to recalculate China’s agriculture sector’s carbon emissions and sinks from 1995 to 2020, taking into account both resource inputs and productive activities. Subsequently, the STIRPAT model is employed to predict alterations in carbon emissions and sinks across different scenarios. The results show that energy consumption, chemical inputs, and farmland soil management have surpassed livestock and poultry breeding as the main contributors to agricultural carbon emissions. Furthermore, this paper classifies 31 provinces in China into five distinct types based on the variations in agricultural carbon emissions and carbon sinks. These types include carbon sink-dominated regions, paddy planting-dominated regions, livestock farming-dominated regions, resource inputs-dominated regions, and composite factor-dominated regions. In addition, the extent of agricultural technology and the magnitude of agricultural development are the key factors impacting China’s agricultural carbon emissions and carbon sinks, respectively. Prior to 2045, agricultural carbon emissions must be directly reduced as much as possible, and their source must be controlled; following that year, the role of carbon sequestration will become more prominent, and the active development of agricultural carbon sinks will be more beneficial in achieving agricultural carbon neutrality.

Ligand-free Ni-Cu bimetallic nanocatalyst: Laser synthesis, characterization and its high performance for borohydride assisted catalytic reduction of 4-nitrophenol

In the present work, nickel and copper bimetallic nanoparticles with three different concentration ratios of 70:30, 50:50, and 30:70 were synthesized by laser ablation of Ni and Cu in deionized water. The suitability of Ni-Cu bimetallics as nanocatalysts was investigated in the catalytic reduction of pollutant 4-nitrophenol. The nanocatalysts were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and ultraviolet-visible (UV–Vis) spectroscopy. The morphology using SEM and TEM indicated that Cu had an elongated or flake-like structure, whereas Ni had a quasi-spherical structure. XPS investigation has been performed to study the elemental composition and chemical states near-surface regions of the generated Ni-Cu bimetallic nanoparticles. XRD and XPS confirm high oxidation of Cu to CuO with approximately no residual Cu metal. However, the XRD patterns did not show complete Ni oxidation to NiO, confirming the presence of a Ni dopant part in the Ni-Cu samples. The behavior of the photoelectron peaks in the XPS spectra suggested that the Ni-Cu nanocomposites exhibited surface charge transfer. Pulsed laser ablation developed ligand-free Ni-Cu nanoparticles, which affected the structure and catalytic properties. The nanocatalyst for 50:50 of Ni and Cu had the highest rate constant, corresponding to the shortest time required to achieve 100 % conversion/reduction of the pollutant dye. The apparent synergistic effect between Ni and Cu is clearly dictated by the amount of Cu embedded in the nanocomposites, with this becoming a key factor in lowering the band gap energy values. Overall, the surface charge transfer rate can enhance the catalytic performance by tuning the Ni and Cu concentrations.

Tau PET positivity predicts clinically relevant cognitive decline driven by Alzheimer's disease compared to comorbid cases; proof of concept in the ADNI study.

β-amyloid (Aβ) pathology is not always coupled with Alzheimer's disease (AD) relevant cognitive decline. We assessed the accuracy of tau PET to identify Aβ(+) individuals who show prospective disease progression. 396 cognitively unimpaired and impaired individuals with baseline Aβ and tau PET and a follow-up of ≥ 2 years were selected from the Alzheimer's Disease Neuroimaging Initiative dataset. The participants were dichotomously grouped based on either clinical conversion (i.e., change of diagnosis) or cognitive deterioration (fast (FDs) vs. slow decliners (SDs)) using data-driven clustering of the individual annual rates of cognitive decline. To assess cognitive decline in individuals with isolated Aβ(+) or absence of both Aβ and tau (T) pathologies, we investigated the prevalence of non-AD comorbidities and FDG PET hypometabolism patterns suggestive of AD. Baseline tau PET uptake was higher in Aβ(+)FDs than in Aβ(-)FD/SDs and Aβ(+)SDs, independently of baseline cognitive status. Baseline tau PET uptake identified MCI Aβ(+) Converters and Aβ(+)FDs with an area under the curve of 0.85 and 0.87 (composite temporal region of interest) respectively, and was linearly related to the annual rate of cognitive decline in Aβ(+) individuals. The T(+) individuals constituted largely a subgroup of those being Aβ(+) and those clustered as FDs. The most common biomarker profiles in FDs (n = 70) were Aβ(+)T(+) (n = 34, 49%) and Aβ(+)T(-) (n = 19, 27%). Baseline Aβ load was higher in Aβ(+)T(+)FDs (M = 83.03 ± 31.42CL) than in Aβ(+)T(-)FDs (M = 63.67 ± 26.75CL) (p-value = 0.038). Depression diagnosis was more prevalent in Aβ(+)T(-)FDs compared to Aβ(+)T(+)FDs (47% vs. 15%, p-value = 0.021), as were FDG PET hypometabolism pattern not suggestive of AD (86% vs. 50%, p-value = 0.039). Our findings suggest that high tau PET uptake is coupled with both Aβ pathology and accelerated cognitive decline. In cases of isolated Aβ(+), cognitive decline may be associated with changes within the AD spectrum in a multi-morbidity context, i.e., mixed AD.

Influence of structural characteristics of Ca1-xNdxW1-xVxO4 ceramics on microwave dielectric properties

Dense Ca1-xNdxW1-xVxO4 (x = 0−0.4) microwave dielectric ceramics were obtained when sintered at 1150 °C for 4 h. A tetragonal scheelite could be formed in the range of x ≤ 0.3, while a composite region with tetragonal scheelite and tetragonal zircon was found at x ≥ 0.4. The relative permittivity (εr) increased from 10.15 to 13.66, mainly attributed to an increase in the ionic polarizability. The quality factor (Q×f) decreased from 61,060 to 32,204 GHz, correlated to the variations in lattice energy and the Raman FWHM. The temperature coefficient of resonant frequency (τf) gradually increased from −54.03 to −23.50 ppm/℃, mainly affected by the rattling effect of W6+/V5+ and the temperature coefficient of ion polarizability (ταm). Ca0.7Nd0.3W0.7V0.3O4 with excellent comprehensive properties (εr = 13.21, Q×f = 35,570 GHz, and τf = −23.50 ppm/°C) were obtained at 1150 °C.

Sustainable wastewater recovery system employing geothermal energy – Performance and feasibility study

In this study, a sustainable wastewater recovery system employing geothermal energy has been proposed. The efficiency of the suggested sustainable system has been simulated using heat transfer. Then, component-wise validation has been carried out with the existing data available in the literature wherever applicable and estimated an error of ± 8 %. The proposed sustainable system’s parametric and performance analyses have employed the developed vapor. From the parametric study, it is observed that hot spring temperatures have a significant influence on sustainable systems. Further, through performance investigation, it is understood that low dam/river/sea water temperatures and enhancing the water condenser effectiveness and flow rate ratio simultaneously improve the system performance. For different climatic regions of India, explored the feasible geothermal hotspots near dams/rivers/seawater and analyzed that among the hot and dry, hot and humid, composite and cold regions, the proposed sustainable system is best suitable at a composite region with a maximum possible water extraction/freshwater generation rate of 0.78 L/h for the given specifications and operating range. Moreover, it is assessed that hot spring temperature is the deciding factor for sustainable system performance in different climatic regions. Further, the current study can be used as a reference for understanding the phenomenon of potential geothermal hotspots for wastewater recovery in various climatic areas

Abstract We036: Recapitulating Cardiac Microenvironment: Elucidating the Role of ECM Components and Architecture on Cardiac Differentiation

The discovery of iPSCs was revolutionary for regenerative medicine, especially as a source to replace a cell population with limited regeneration capability, like cardiomyocytes (CMs). However, the exact mechanism(s) governing how the microenvironment influences cardiac differentiation at a cellular scale is still widely unclear. To bridge this gap, we created an in vitro fibrous model from a decellularized porcine cardiac extracellular matrix. The aim is to assess the impact of the microenvironment, specifically the effects of protein composition and micro-architecture, on the cardiac differentiation of iPSCs. To study the role of protein composition, atrial and ventricular regions of the porcine heart are manually identified and separated as their protein composition is observed to be different. To test this, the material was subjected to proteomics analysis with LS-Mass Spectrometry where about 1000 proteins were identified in the ventricular region and only 300 proteins in atria. The decellularized tissue was tested for complete removal of nuclei by staining and further validated with DNA quantification. The dECM was blended with synthetic polymer (polycaprolactone) for electrospinning. The average collected fiber diameter was 14.8 ± 3.9 μm. The fibrous scaffolds were seeded with iPSCs and differentiated towards cardiac lineage. dECM samples show comparable signs of biocompatibility as laminin-521 coated TCPS, forming clusters throughout the differentiation process indicating that the scaffolds encourage cardiac differentiation. Further analysis is being conducted to compare the cellular expressions of differentiation markers including mesoderm formation, cardiac specification, and cardiomyocyte structural and functional markers. The effects of the ECM composition will be checked with myosin light and heavy chain expressions, as their expressions vary in the atrial and ventricular regions of the heart.

Investigation on itraconazole solubility in aqueous solutions based on models, solvent effect, thermodynamic analysis and quantum chemical calculations

The mole-fraction solubility of itraconazole in four aqueous blends of ethanol/isopropanol/DMSO/methanol within the temperature range of 283.15 to 323.15 K was experimentally obtained using the isothermal shake-flask method. Under the identical temperature and ethanol/isopropanol/DMSO/methanol composition, itraconazole solubility in DMSO+water is much higher than that in ethanol/isopropanol/methanol + water. At the same temperature, the solubility increases monotonically with organic solvent concentration. X-ray power diffraction analysis demonstrated that over the course of the investigations, there was no crystal transition or solvate formation. The modified van’t Hoff-Jouyban-Acree and Jouyban-Acree models adequately related the solubility to solvent composition and temperature, with relative average deviations (RADs) not exceeding 7.65 %. Furthermore, the extended Hildebrand solubility approach was utilized to quantitatively characterize the solubility behavior at 298.15 K for the mixtures of ethanol/isopropanol/DMSO/methanol plus water. In both instances, the RADs were maintained below 4.12 %. The solubility parameter and dipolarity-polarizability of solutions have a major impact on the solubility fluctuation, as indicated by the analysis of the linear solvation energy relationship. The preferential solvation of itraconazole at 298.15 K was examined using the efficient approach of inverse Kirkwood-Buff integrals. The preferred solvation parameters showed positive values in blends within rich and moderate ethanol/isopropanol/DMSO/methanol composition regions. This suggests that the organic solvents preferentially solvated itraconazole. When itraconazole dissolved in the blends, thermodynamic analysis of the entropy-enthalpy compensation and dissolution parameters revealed both an endothermic and an enthalpy-driven mechanism. Furthermore, the microscopic electrostatic characteristics of basicity and acidity were effectively demonstrated by means of the electrostatic potential of molecular surface. The −C=O and −N=groups of the itraconazole molecule, which link the five-membered ring, are the primary targets of the electrophilic attack. An independent gradient model based on Hirshfeld partition analysis was used to demonstrate the weak interactions between itraconazole and solvents.

High Defect Tolerance in Heavy‐Band Thermoelectrics

AbstractThe insensitivity of thermoelectric (TE) performance to defects and impurities induced by off‐stoichiometry or low‐purity raw elements is crucial for the low‐cost mass production of highly efficient TE materials. Here it is demonstrated that heavy‐band TE materials with high optimized carrier concentration can exhibit a high tolerance against the off‐stoichiometry in their composition. Using the heavy‐band half‐Heusler compounds as examples, it is found that for ZrNiSn with optimal carrier concentration, the off‐stoichiometry of the nominal composition in between ±5% only results in a fluctuation of its peak zT value less than 10%. A composition‐zT phase diagram is thus established, guiding the exploration of a wide nominal composition region with peak zT values exceeding 1.0. The high defect tolerance observed in heavy‐band TE materials enables the achievement of high TE performance using low‐purity raw elements. As demonstrated in several systems, including n‐type ZrNi(Sn, Sb), (Zr, Nb)CoSb, and p‐type ZrCo(Sb, Sn), comparable zT values are attained when utilizing low‐purity raw elements (≈99.5%), instead of the high‐purity ones (99.95–99.999%), leading to substantial cost saving. These findings highlight the importance of understanding defect tolerance in TE materials, which could offer an additional advantage for their practical applications.

Nonlocal active sound control for composite regions

In the active sound control problem, additional sound sources, known as control sources, are implemented at the perimeter of a protected domain. The control sources can generate secondary sound inside the shielded domain, which attenuates incoming noise. This leads to an inverse source problem. Such a problem becomes much more complicated if some desired sound is generated inside the protected area. The algorithm, known as nonlocal active sound control, successfully tackles this problem due to the projection property of the nonlocal operators involved. With the application of nonlocal control, noise generated outside the shielded domain is attenuated while the internal component of sound remains unaffected. In the present paper, the approach of nonlocal active sound control is significantly modified to be applicable to composite domains. In the test cases, three different sound propagation patterns are realized such as sound shielded from peers, free propagation, and selective sound cancelation. Numerical simulation is carried out in both frequency and time domains for broadband regimes. The results show that, even with a relatively small number of sensors and control sources, significant noise attenuation can still be achieved for a predetermined communication pattern among individual subdomains.

Engineering of Reversibly Cross-Linked Elastomers Toward Flexible and Recyclable Elastomer/Carbon Fiber Composites with Extraordinary Tearing Resistance.

Carbon fiber (CF)-reinforced polymers (CFRPs) demonstrate potential for use in personal protective equipment. However, existing CFRPs are typically rigid, nonrecyclable, and lack of tearing resistance. In this study, flexible, recyclable, and tearing resistant polyurethane (PU)-CF composites are fabricated through complexation of reversibly cross-linked PU elastomer binders with CF fabrics. The PU-CF composites possess a high strength of 767MPa and a record-high fracture energy of 2012kJ m-2. The high performance of the PU-CF composites originates from the well-engineered PU elastomer binders that are obtained by cross-linking polytetrahydrofuran chains with in situ-formed nanodomains composed of hierarchical supramolecular interactions of hydrogen and coordination bonds. When subjected to tearing, the force concentrated on the damaged regions of the PU-CF composites can be effectively distributed to a wider area through the PU binders, leading to a significantly enhanced tearing resistance of the composites. The strong interfacial adhesion between PU binders and the CF fabrics enables the fracture of the CF in bundles, thereby significantly enhancing the strength and fracture energy of the composites. Because of the dynamic nature of the PU elastomer binders, the PU-CF composites can be recycled through the dissociation of the PU elastomer binders.

Enhanced CHF of pool boiling and its predictive correlation for heterogeneous distributed composite microstructured surfaces with microcavities on micro-pin-fins

In the present study, several heterogeneous distributed composite microstructured surfaces (HDCMs) with different geometry parameters were prepared. The effect of the widths of the composite microstructured region, the widths of the smooth channels, the pitch of the micro-pin-fins, and the porosity of the surfaces on the pool boiling performance in HFE-7100 was examined under different liquid subcoolings. During the experiments, the three-phase contact lines of bubbles can be restricted by composite microstructured regions. Thus, reasonable geometry parameters can further enhance the liquid supply, promoting pool boiling heat transfer performance. The maximum critical heat flux of the HDCM is 14.1 % higher than that of the uniformly distributed composite microstructured surface (UDCM). Considering the effects of subcooled Jakob number (Jasub), composite microstructured region density number (SD), capillary resistance number (CR), and porosity (φ) on the critical heat flux (CHF) of HDCMs, an empirical correlation predicted the CHF for DCMs with different geometry parameters was proposed. The prediction results meet well with the experimental data, with an error within ±15 %.

Evaluation of photocatalytic properties of TiO2/g-C3N4 core-shell hybrid catalyst supported on Sr4Al14O25:eu,dy phosphor

TiO2/g-C3N4 hybrid compounds were supported as core-shell catalyst on Sr4Al14O25:Eu,Dy phosphor powder by a 2-step hydrothermal and solvothermal self-assembly method. Surface and chemical characterizations confirmed that the phosphor substrate and the hybrid catalysts co-existed as a multi-composite material. Where nano spherical TiO2 particles were dominant as core/shell catalyst. Diffuse reflectance spectra were shifted toward the visible light region (400 nm to 600 nm) in composites with g-C3N4 as shell-catalyst. X-ray photon spectroscopy (XPS) confirmed the chemical integrity and binding of g-C3N4 on phosphor/TiO2 material. When g-C3N4 was coated as shell-catalyst on phosphor/TiO2, superior photocatalytic performances of above 90% efficiency were obtained in comparison to where TiO2 was coated as shell-catalyst under both ultraviolet and visible light illumination. Thus, g-C3N4 is more active as shell-catalyst owing to its lower band gap of 2.7 eV than core TiO2 (3.2 eV).