Heterogeneous Phase Research Articles

Tracking plasma biomarkers in cognitively unimpaired individuals at risk of Alzheimer’s disease

AbstractAlzheimer’s disease (AD) is as a continuum that includes a preclinical phase, where individuals are cognitively unimpaired but there is evidence of amyloid‐β (Aβ) and tau pathology, followed by a clinical phase (including mild cognitive impairment and dementia). This preclinical phase is not a uniform or unvarying phase, but it is a long process during which Aβ and tau gradually accumulates until overt Aβ plaque deposition and neurofibrillary tangles are present. Moreover, this is a heterogeneous phase, there are differences in the rate of progression of those individuals that are Aβ‐positive to cognitive impairment and some of them will not even develop symptoms. It is important to develop biomarkers that accurately detect Preclinical AD, but also biomarkers to stage the disease, and prognostic biomarkers that identify those individuals that will progress to cognitive impairment. Furthermore, amid the new developments of disease modifying treatments, there is an unmet need to develop biomarkers to predict and monitor the response to an intervention.We now have a range of plasma biomarkers that detect symptomatic AD but also increase in Preclinical AD, including several epitopes of p‐tau (pT181, pT217, pT231), Aβ42/40, GFAP and NfL. Yet, there are differences between them. They may differ on which point of the long preclinical stage they start to increase, their discrimination accuracy, their longitudinal changes across the disease continuum or the physiopathological mechanism that they indicate. Moreover, the performance of plasma biomarkers may be influenced by sex and gender, race and ethnicity, or comorbidities. Therefore, the choice of the plasma biomarker may differ depending on its goal.In this presentation, plasma biomarkers in Preclinical AD will be reviewed and their differential roles will be discussed.

Double heterogeneous structures induced excellent strength–ductility synergy in Ni40Co30Cr20Al5Ti5 medium-entropy alloy

The application of single-phase face-centered cubic (FCC) medium entropy alloys (MEAs) in the engineering industry is often hindered by the challenge of insufficient strength. In this study, a novel non-equiatomic ratio Ni40Co30Cr20Al5Ti5 MEA was successfully fabricated. Through the well-designed mechanical heat treatment processing, we introduced a heterogeneous grain structure comprising 67.4% fine grain and 32.6% coarse grain. Additionally, heterogeneous size L12 phases consisting of 18.7% submicron precipitates and 11.7% nano-sized precipitates, were incorporated into the alloy. Tensile tests conducted at room temperature revealed that the double heterogeneous structure alloy demonstrated remarkable strength–ductility synergy. It exhibited a yield strength of 1200 MPa, an ultimate tensile strength of 1560 MPa and a total elongation of 33.6%. The exceptional strength of the alloy can be primarily attributed to heterogeneous deformation induced strengthening, grain boundary strengthening and precipitation strengthening. The excellent ductility is mainly attributed to the high-density stacking faults and Lomer–Cottrell locks. This study not only contributes to the clarification of the strengthening and deformation mechanism of double heterogeneous structure alloys but also provides an effective strategy for the development of high-performance alloys with high strength and ductility.

Stable chimera states: A geometric singular perturbation approach.

Over the past decades, chimera states have attracted considerable attention given their unexpected symmetry-breaking spatiotemporal nature and simultaneously exhibiting synchronous and incoherent behaviors under specific conditions. Despite relevant precursory results of such unforeseen states for diverse physical and topological configurations, there remain structures and mechanisms yet to be unveiled. In this work, using mean-field techniques, we analyze a multilayer network composed of two populations of heterogeneous Kuramoto phase oscillators with coevolutive coupling strengths. Moreover, we employ the geometric singular perturbation theory through the inclusion of a time-scale separation between the dynamics of the network elements and the adaptive coupling strength connecting them, gaining a better insight into the behavior of the system from a fast-slow dynamics perspective. Consequently, we derive the necessary and sufficient condition to produce stable chimera states when considering a coevolutionary intercoupling strength. Additionally, under the aforementioned constraint and with a suitable adaptive law election, it is possible to generate intriguing patterns, such as persistent breathing chimera states. Thereafter, we analyze the geometric properties of the mean-field system with a coevolutionary intracoupling strength and demonstrate the production of stable chimera states. Next, we give arguments for the presence of such patterns in the associated network under specific conditions. Finally, relaxation oscillations and canard cycles, seemingly related to breathing chimeras, are numerically produced under identified conditions due to the geometry of our system.

Engineering the fracture resistance of 2H-transition metal dichalcogenides using vacancies: An in-silico investigation based on HRTEM images

Vacancy engineering of 2H-transition metal dichalcogenides (2H-TMDs) has recently attracted great attention due to its potential to fine-tune the phonon and opto-electric properties of these materials. From a mechanical perspective, this symmetry-breaking process typically reduces the overall crack resistance of the material and adversely affects its reliability. However, vacancies can trigger the formation of heterogeneous phases that synergistically improve fracture properties. In this study, using MoSe2 as an example, we characterize the types and density of vacancies that can emerge under electron irradiation and quantify their effect on fracture. Molecular dynamic (MD) simulations, employing a re-parameterized Tersoff potential capable of accurately capturing bond dissociation and structural phase changes, reveal that isolated transition metal monovacancies or chalcogenide divacancies tend to arrest the crack tip and hence enhance the monolayer toughness. In contrast, isolated chalcogenide monovacancies do not significantly affect toughness. The investigation further reveals that selenium vacancy lines, formed by high electron dose rates, alter the crack propagating direction and lead to multiple crack kinking. Using atomic displacements and virial stresses together with a continuum mapping, displacement, strain, and stress fields are computed to extract mechanistic information, e.g., conditions for crack kinking and size effects in fracture events. The study also reveals the potential of specific defect patterns, “vacancy engineering,” to improve the toughness of 2H-TMDs materials.

Alloying strategies for additive manufacturing of Ti6Al4V based alloys, composites and functionally graded materials: Microstructure and phase evolution of intra and inter-layer

The further developments of additive manufacturing (AM) provides a possibility for Ti6Al4V and its functionally graded materials (FGMs), but limits further applications due to its low ductility, low microhardness and poor wear resistance. The key lies in the presence of microstructures such as epitaxial columnar β-grain orientation and heterogeneous phase distribution in AM Ti6Al4V, as well as the interfacial bonding problems (intermetallic phases, delamination, cracking) in AM Ti6Al4V FGMs. In order to address these fundamental intra and inter-layer problems, firstly the microstructure and phase evolution process of AM Ti6Al4V columnar-to-equiaxed transformation (CET) promoted by some alloying strategies was summarized in this paper according to alloying elements and reinforcing particle types. Subsequently, controlled changes in the composition and microstructure of AM Ti6Al4V FGMs were achieved by adding interlayers/introducing gradient interfaces, and the metallurgical reactions and phase transformation mechanisms that inhibit the formation of intermetallic compounds and interfacial defects were explored. Finally, the difficulties and future research directions for alloying strategies to achieve high strength and ductility of AM Ti6Al4V were presented. This review aims to improve the reliability of AM Ti6Al4V and its FGMs for applications in critical load-bearing structures through in-situ alloying and multi-material for the microstructure design of AM Ti6Al4V.

Preferred method and performance evaluation of heterogeneous composite phase change material (CPCM) wallboard in different seasons

The application of phase change materials (PCMs) in building envelopes has been developed in past decades and many strategies have been adopted to improve the heat resistance and capacity performance. However, rare studies focused on optimizing these characteristics of PCM wallboard in different seasons and providing preferred method for selecting the optimal PCMs. This study constructed a heterogeneous wall acting in different seasons and developed a pre-screening method of PCMs based on the analytic hierarchy process. CA-HD/EG with higher thermal conductivity (2.16 W/(m·K)) and lower melting point (25.4 °C) acted as the inner layer, and paraffin/porous silica with lower thermal conductivity (0.37 W/(m·K)) and higher melting point (29.3 °C) acted as the outer layer. Two experimental boxes were built to compare the thermal performance of CPCM and gypsum wallboard. The decrement factor in winter increased by 6.7 %, and the heat storage coefficient in summer increased by 0.97. The thermal comfort duration in winter was extended by 17.9 %, and the thermal load leveling in summer was reduced by 11.5 %. The heating/cooling water supply duration was shortened by 2.5 h, resulting in an energy-saving rate of 13.3 %. Consequently, the CPCM wallboard maintained a better indoor thermal environment with a lower energy consumption.

A comparative study on physico-chemical, optical, magnetic and ferroelectric properties of undoped BiFeO3 and Ni-doped BiFeO3 nanoparticles

Undoped BiFeO3 and Ni-doped BiFeO3 nanostructures were synthesised via colloidal gel, followed by a combustion reaction at a processing temperature of 500 °C, for testing their multiferrioic properties. Powder X-ray diffraction studies reveal the rhombohedral perovskite crystal structure for the synthesized pure BiFeO3, whereas Ni-doped BiFeO3 sample shows the formation of the rhombohedral perovskite structure along with the heterogeneous phase contains Fe2O3 and Bi2Fe4O9. The energy band gap (Eg) of Ni-doped BiFeO3 was found to be reduced (1.87 eV) compared to the Eg value (2.02 eV) of undoped BiFeO3, as confirmed by the Tauc plot. The synthesized compounds were tested for their vibrational bands by FT-IR analysis, and strong absorption bands were found at 555 cm−1, which attribute the vibration bonds of Bi-O and Fe-O. The aggregated particles with irregular morphology appeared in the TEM images of the undoped BiFeO3 and the presence of Ni-doped incorporation of BiFeO3. The ferromagnetic and ferroelectric behaviour of the synthesized undoped and Ni-doped BiFeO3materials was noticed in the magnetization vs. magnetic field (M−H) loops and polarization–electric field (P-E) at room temperature. The areas of the hysteresis loop, coercive force, magnetic saturation, saturation polarization, remanent magnetization, and polarization of Ni-doped BiFeO3 were decreased compared to undoped BiFeO3. The investigated Ni-doped BiFeO3 results were elucidated to assess the soft magnetic nature of device applications.

Evaluation and Failure Mechanism of High‐Temperature Microwave Absorption for Heterogeneous Phase Enhanced High‐Entropy Transition Metal Oxides

AbstractHerein, magnetic and conductive heterogeneous nickel‐matrix alloy is in situ constructed in the high‐entropy transition metal oxide matrix using a reductive circumstance, to form the high‐temperature resistant microwave absorbers. The ohmic, dielectric polarization and magnetic loss are enhanced synergistically, prompting the improvement of loss capacity and optimization of the impedance matching feature. The composites achieve over 90% absorption in the whole Ku band with a thickness of just 1.55 mm at room temperature. Moreover, the in situ high temperature measured microwave absorption keeps stable till 500 °C. In situ characterizations are employed to investigate the evolution processes and failure mechanisms. As the temperature elevates, there are three distinct stages. The absorber goes through minor chemical reactions, consequent elimination of magnetic loss, and a rapid increase in electroconductivity. These behaviors culminate in impedance mismatch, finally worsening its absorption performance at elevated temperatures. The proposed evaluation process reveals how the above irreversible and reversible behaviors affect high‐temperature microwave absorption, providing an effective theoretical basis for the design of high‐temperature microwave absorbers.

Photoreduction of Anthracenes Catalyzed by peri-Xanthenoxanthene: a Scalable and Sustainable Birch-Type Alternative.

The typical Birch reduction transforms arenes into cyclohexa-1,4-dienes by using alkali metals, an alcohol as a proton source, and an amine as solvent. Capitalizing on the strong photoreductive properties of peri-xanthenoxanthene (PXX), herein we report the photocatalyzed "Birch-type" reduction of acenes by employing visible blue light irradiation at room temperature in the presence of air. Upon excitation at 405 or 460 nm in the presence of a mixture of N,N-diisopropylethylamine (DIPEA) and trifluoromethanesulfonimide (HNTf2 ) in DMSO, PXX photocatalyzes the selective reduction of full-carbon acene derivatives (24-75 %). Immobilization of PXX onto polydimethylsiloxane (PDMS) beads (PXX-PDMS) allowed the use of the catalyst in heterogeneous batch reactions, giving 9-phenyl-9,10-dihydroanthracene in high yield (68 %). The catalyst could easily be recovered and reused, with no notable drop in performance observed after five reaction cycles. Integration of the PXX-PDMS beads into a microreactor enabled the reduction of acenes under continuous-flow conditions, thereby validating the sustainability and scalability of this heterogeneous-phase approach.

Macroscale insights into heterogeneous hydrate formation and decomposition behaviors in porous media

Hydrocarbon fuels are distributed unevenly in the earth, known as heterogeneity. How to harness the nature of heterogeneity for sustainable development of energy sources is the key issue. Herein, the controllable process of heterogeneous hydrate phase transition is firstly realized at macroscale, and three typical hydrate distribution patterns (dispersed, massive, and layered) with the same hydrate saturation are successfully achieved. Macroscale observations revealed the kinetic of heterogeneous hydrate phase transition governed by water and gas transfer in pores. Specifically, a new sequence of “nucleation-growth-migration” driven by water migration for heterogeneous hydrate formation in porous media is proposed. In contrast, gas transportation capacity and reformation probability determine the heterogeneous hydrate decomposition efficiency. Significantly, the phase transition rates between heterogeneous and homogeneous hydrate differs by 2 to 3 times due to mass migration. These results suggest that the porous sediments with facilitated water migration under strong capillary effect are preferable for heterogeneous distribution of hydrocarbon fuels, providing explanations for the enrichment of methane hydrate in marine coarse-grained sandy sediment. Nevertheless, the distribution heterogeneity could be challenging to efficient and economic gas production, raising the demand for targeted approaches to develop natural gas hydrate with different distribution patterns. More significantly, the enhanced hydrate formation rate in porous media by controllable heterogeneous hydrate formation method offered by this work also indicates the feasibility in hydrocarbon capture, storage and transport via hydrate-based technologies.

Modeling of CO2 Adsorption on Surface-Functionalized Rubber-Seed Shell Activated Carbon: Isotherm and Kinetic Analysis

Currently, adsorption is considered a promising technology for CO2 separation with a wide range of adsorbents. A detailed study of equilibrium and kinetics plays a crucial role in the design and operation of industrial adsorption units. In this study, isotherm and kinetics of CO2 adsorption on two RSS-derived AC samples previously prepared in our laboratory were evaluated using equilibrium experiments for pure CO2 at 25 °C and 40 °C and 1 bar. Blank and IL-functionalized AC showed CO2 adsorption capacity of 2.16 mmol/g, 1.96 mmol/g, 1.12 mmol/g and 1.71 mmol/g at 25 °C and 40 °C, respectively. Langmuir, Freundlich, and Temkin equations were used to model adsorption isotherm in low-pressure regions. The obtained results revealed that the Freundlich model provides an accurate fitting to the experimental findings, which indicate that the adsorption process occurs in a heterogeneous phase. Additionally, kinetic analysis was performed by using four empirical models, namely pseudo-first order, pseudo-second order, Elovich, and Avrami’s fractional models. Among the considered kinetic models, the pseudo-second order model fits best for both blank and IL-functionalized AC. Intra-particle and Boyd’s film diffusion models were evaluated for the adsorption mechanism.

Direct Observation of Vacancy-Cluster-Mediated Hydride Nucleation and the Anomalous Precipitation Memory Effect in Zirconium.

Controlling the heterogeneous nucleation of new phases is of importance in tuning the microstructures and properties of materials. However, the role of vacancy-a popular defect in materials that is hard to be resolved under conventional electron microscopy-in the heterogeneous phase nucleation remains intriguing. Here, this work captures direct in situ experimental evidences that vacancy clusters promote the heterogeneous hydride nucleation and cause the anomalous precipitation memory effect in zirconium. Both interstitial and vacancy dislocation loops form after hydride dissolution. Interestingly, hydride reprecipitation only occurs on those vacancy loop decorated sites during cooling. Atomistic simulations reveal that hydrogen atoms are preferentially segregated at individual vacancy and vacancy clusters, which assist hydride nucleation, and stimulate the unusual memory effect during hydride reprecipitation. The finding breaks the traditional view on the sequence of heterogeneous nucleation sites and sheds light on the solid phase transformation related to vacancy-sensitive alloying elements.

Monovalent ion doping to enhance the performance of cobalt-free Sm0.5Sr0.5FeO3-δ cathode for YSZ fuel cells

Solid oxide fuel cells (SOFCs) are energy conversion devices that can solve the energy crisis and environmental pollution, but the low electrochemical performance at intermediate temperatures is still an urgent problem to be addressed. In this work, we investigate the effect of K and F doping on the performance of conventional cobalt-free cathode SSF. XRD demonstrates that SSF, SSKF, SSFF, and SSKFF each display a cubic perovskite structure. Additionally, HT-XRD reveals that SSF, SSKF, and SSFF exhibit exceptional thermal stability, while SSKFF produces the impurity phase Sr3Fe2O7 during the test. XPS suggests that the improvement in SSF performance, resulting from F and K doping, can be largely attributed to the increase in adsorbed oxygen content, which enhances the ORR catalytic activity. The O2-TPD outcomes indicate that F and K doping stimulate the formation of oxygen vacancies at higher temperatures, thus promoting ORR catalytic activity. Experimentally, the electrochemical impedance spectra results indicate that both K and F doping led to a reduction in the value of polarization resistance, which decreased by over 20% at 800 °C. Regarding the output performance, both K and F doping resulted in a substantial increase in the output power from 670.05 to 825.88 and 796.76 mW·cm−2 respectively, at 800 °C. However, co-doping with F and K led to a notable reduction in polarization impedance and output power, possibly due to the formation of heterogeneous phases during testing. The results indicate that enhancing the electrochemical performance of SSF can be achieved through the doping of K cations and F anions, but co-doping leads to a decreased performance.

A Drive Towards Elemental Simplicity in Cathode Design by Controlling Grain Growth Behavior

Sodium-ion battery technologies are emerging as an alternative to lithium-ion batteries by utilizing the earth abundant, widely distributed, and low-cost sodium resources. Among different types of sodium ion cathodes, transition metal based layered oxide cathodes have a superior edge due to their comparatively higher energy density, lower cost, environment friendly raw materials, and similar synthesis chemistry as the already commercialized lithium-ion battery cathode materials. They also enable the incorporation of iron, an abundant, low-cost, and environmentally benign element, replacing the toxic and expensive cobalt.In such layered oxide-based cathodes, transition metals exhibit heterogenous elemental and oxidation state distribution at different depths of the particles (e.g., from the surface to bulk) which can influence the stability, mechanical integrity, and electrochemical performance of these particles to a significant extent. The inherent local structural and electronic state heterogeneity developed in these materials during synthesis can modulate the charge distribution heterogeneity and consequent phase transitions during cycling, ultimately controlling the battery performance.In this work, a sodium transition metal layered oxide cathode is synthesized using a co-precipitation method followed by high temperature calcination under different calcination durations. Calcining the material at different conditions lead to the formation of particles with different morphologies and grain growth behavior. Using electron microscopy and Xray diffraction techniques, the grain growth behavior at different stages of calcination is studied. This will guide the design of particles with better morphologies and grain orientation which demonstrate improved electrochemical performance. Transition metal distribution and oxidation state change at different depths of the particles are probed using synchrotron based Xray absorption spectroscopy and three-dimensional Transmission Xray microscopy. The particles are probed at the surface, subsurface and deep into the bulk, which show heterogeneity in the distribution of transition metal oxidation state and provide insight into the phase transitions during calcination. This study can pave the way for better understanding of phase evolution during synthesis and improved design of cathode particle morphology and composition by identifying and eliminating the detrimental phases occurring during different stages of calcination.

(Digital Presentation) Electrospun Bimetallic Cu/Zn Selenide @ Carbon Nanofiber Electrocatalysts for Oxygen Evolution and Oxygen Reduction

Electrochemical water splitting and fuel cells are intriguing ways to achieve a potentially sustainable and clean energy1. A greater focus on these energy technologies necessitates the design and development of highly active, cost-effective electrocatalysts that can substitute state of the art noble metal based materials2. In this context, metal selenide-based materials are important owing to their superior stability and electrical conductivity3. Their high specific surface area and abundant active sites on the surfaces make them strong candidates for use as electrocatalysts. Herein, heterostructured copper selenide and zinc selenide encased in carbon nanofibers (CZSe@C-450) synthesized using electrospinning and selenization techniques are used as bifunctional electrocatalysts. The novel architecture and tunable confinement of bimetallic selenides with the carbon matrix results in improved electrochemical performance in both oxygen evolution (OER) and oxygen reduction reactions (ORR)4. CZSe@C-450 exhibits a low overpotential of 260 mV at 10 mA cm−2 for oxygen evolution reaction and exhibits a half-wave potential (E1/2) of 0.88 V for oxygen reduction reaction. Further, the creation of a heterogeneous phase boundary between copper selenide and zinc selenide in the CZSe@C-450 enhances the built-in potential, local atomic disorder, and mismatch in the lattice that leads to lowering the surface energy. This gives rise to creation of catalytically active edge sites and phase boundaries, which contribute to the enhanced performance and good stability in both OER and ORR5,6.

Co-Doped TiO2 Aerogel with Enhanced Light Absorption Properties for CO2 Photocatalytic Reduction and H2o Splitting

Carbon dioxide (CO2) is a major component of greenhouse gases, whose amount in the atmosphere is gradually increasing. The use of various methods to reduce CO2 has become a hot research topic. However, CO2 being chemically stable, traditional methods such as thermal ones are not efficient. Artificial photosynthesis may alternatively reduce CO2 under mild conditions. Therefore, the development of innovative photocatalysts to produce high-value-added products from CO2 reduction has attracted wide interest from academia and industry, providing new insights into the utilization of CO2. However, the activation of CO2 remains difficult, the reaction path is complex and the selectivity is low. Therefore, the design of photocatalysts with both high selectivity and conversion rate for CO2 reduction is of great scientific and strategic importance.1 TiO2 is a common photocatalyst, but pure TiO2 is only responsive to UV light. Hence, modification of TiO2 by doping or co-catalyst loading has been widely studied to enhance its response to visible light. Aerogels have a high specific surface area and a tunable porosity, both features which are very suitable for catalysis. In the case of CO2 reduction, high specific surface area will favor CO2 adsorption, which is beneficial for the following activation steps.Therefore, based on the previous work on aerogels in our group,2 a series of TiO2 aerogels doped with niobium and nitrogen were synthesized, and Cu was deposited at the surface of the aerogel as a co-catalyst to help CO2 reduction.Obtained photocatalysts were characterized to determine their crystallographic structure (XRD), composition (EDX, XPS), morphology (SEM, N2 sorption) and optical properties (UV-Vis absorption). After calcination, the anatase phase of TiO2 was detected, without any heterogeneous phase generated after Nb and N doping. Nb doping made the anatase (101) peak blue-shifted due to the pinning effect, and the maximum possible doping amount of Nb was 10 at. % in our case. Moreover, no CuxO species were observed in the XRD patterns of Cu/TiO2, which tentatively indicates that it is uniformly distributed as nanoscale particles or domains.The specific surface area (SBET) obtained from N2 sorption experiments was higher for TiO2 aerogel (72 m2/g) than for commercial catalyst P25 (50 m2/g). After Nb doping, the particle size of TiO2 decreased (statistics from SEM image) and as a consequence, SBET was significantly increased (123 m2/g for 10 at. % of Nb).The light absorption ability of TiO2 aerogels was notably shifted in the visible light region after doping, resulting in a narrower bandgap. The visible light absorption performance was even more enhanced after cupper deposition, maybe due to localized Surface Plasmon Resonance effect (LSPR) of Cu2+.The photocatalytic performance was evaluated in a homemade photocatalytic reactor, illuminated with a Xe-light source simulating sunlight and equipped with a monochromator and an optical power meter to investigate the mechanism of photocatalytic reactions.Cu/TiO2: Nb, N aerogel photocatalysts were tested for CO2 photocatalytic reduction, and promising methanol yields were obtained. Parameters such as temperature and pressure and feed ratios will be adjusted to optimize selectivity and conversion rate. The prepared catalysts will also be evaluated for hydrogen production by water splitting. Reference: O. Ola and M. M. Maroto-Valer, J. Photochem. Photobiol. C Photochem. Rev., 24, 16–42 (2015).C. Beauger, L. Testut, S. Berthon-Fabry, F. Georgi, and L. Guetaz, Microporous Mesoporous Mater., 232, 109–118 (2016). Figure 1

Annealing temperature-dependent CdS phase tunability in improving photocatalytic efficiency towards aquatic dye decomposition

Combinations of different materials can improve the functionality of a composite. Heterogeneous structures that consist of various crystalline phases in a single material may also improve the physical and catalytic properties. In this work, we have synthesized highly crystalline CdS with cubic, hexagonal, and heterogeneous phases through precipitation, followed by varying the annealing temperature. The photocatalytic degradation was performed on aqueous rhodamine 6G (R6G) dye as a model pollutant under UV irradiation. From the results, UV–Vis analysis revealed that the heterogeneous structure yields the most intense absorption with a reduced band gap, which is useful for improved photocatalytic reactions. The SEM image demonstrates that the heterogeneous CdS contains more tiny granule particles that disperse extensively over the surface. As a consequence, heterogeneous CdS shows enhanced photocatalytic degradation efficiency and rate constant, which may serve as a future photocatalyst for wastewater remediation.

Coercivity modulation of FeCoCrMoTi films by artificial magnetic phase defects engineering based on multilayer structure

FeCoCr-based films have been considered as promising candidates for next-generation magnetic code disk materials used in high-accuracy magnetic rotary encoders. However, realizing high coercivity with sufficient remanent magnetization in FeCoCr-based films with in-plane anisotropy to ensure suitable disturbance-rejection performance and detectability of magnetic pole pairs is a critical issue, which hinders their practical applications. In this study, we demonstrated an in-plane anisotropic [Ta(20 nm)/FeCoCrMoTi(100 nm)]2/Ta(10 nm) multilayer film (M20 sample) with a high coercivity of 945 Oe and a sufficient remanent magnetization of 2890 Oe, which is 92.1% and 63.1% higher than FeCoCrMoTi(200 nm)/Ta(10 nm) film (SL sample), respectively. Detailed microstructure characterization using atomic resolution scanning transmission electron microscopy (STEM) indicates that the high coercivity originates from the domain-wall pinning effect induced by three factors including grain refinement and heterogeneous phases generation and composition fluctuation of modulated phases. X-ray absorption fine structure (XAFS) and X-ray photoelectron spectroscopy (XPS) analyses reveal that the high remanent magnetization is ascribed to the higher relative content of Fe2Ta phases with strong ferromagnetism than that of Co2Ta phases with weak ferromagnetism.

Mineralogical Controls on the Ti Isotope Composition of Subduction Zone Magmas

AbstractThe positive Ti isotope versus SiO2‐content correlation in igneous rocks reflects the fractional crystallization of Ti‐bearing oxide minerals. However, Ti isotope variations of subduction‐related igneous rocks indicate that the Ti isotope compositions of their mantle sources are heterogeneous and additional mineral phases may promote Ti isotope fractionation. We have determined the Ti isotope composition of well‐characterized subduction‐related basalts, andesites and boninites. Samples from the Solomon Islands, the Troodos ophiolite in Cyprus, and Cape Vogel in Papua New Guinea show small but resolvable variations that may be related to differences in their mantle sources. Specifically, the δ49Ti of boninites (+0.109‰ to +0.168‰) is slightly higher than that of tholeiites (−0.027‰ to +0.111‰) from the same localities (Troodos in Cyprus and Cape Vogel in Papua New Guinea). Modeling suggests the partial melting of progressively depleted mantle sources where residual Cr‐spinel plays a greater role in controlling the Ti budget during partial melting. More pronounced variations in δ49Ti are clearly linked to the fractional crystallization of Ti‐oxides: Samples from Rabaul Volcanic Complex (New Britain, Papua New Guinea) show increasing δ49Ti (up to +0.373‰) with increasing Ti/V and decreasing Dy/Yb. Fractional crystallization models suggest that oxide minerals and amphibole are needed to sufficiently increase the δ49Ti of these magmas. Our study highlights that the combination of diagnostic trace element patterns and Ti isotope compositions in subduction‐related igneous rocks can be a powerful tool to constrain petrogenetic processes and to discriminate between different crystallizing mineral phases.

Synchrotron High-Energy X-ray & Neutron Diffraction, and Laser-Scanning Confocal Microscopy: <i>In-Situ</i> Characterization Techniques for Bulk Nanocrystalline Metals

This report is aimed at giving an overview of the significance of the novel and innovative microstructural and microscopic characterization techniques for bulk nanostructured metals processed by severe plastic deformation, specifically high-pressure torsion (HPT). In practice, the microstructural relaxation behavior upon heating of nanostructured 316L stainless steel and CoCrFeNi high-entropy alloy was characterized by in-situ heating neutron diffraction measurements; the heterogeneous phase distribution of an HPT-bonded hetero-nanostructured Al-Mg alloy was examined using synchrotron high-energy X-ray diffraction; and the microstructural evolution upon heating of a nanostructured CoCrFeNiMn high-entropy alloy was examined by laser-scanning confocal microscopy. These novel techniques are complementary to each other and any other in- or ex-situ testing methods, especially when nanocrystalline metals are transforming microstructurally and compositionally with temperature and time in a hierarchical manner. The outcomes of the studies emphasize the importance of the methodologies and the development of characterization techniques for further in-depth exploration in the research field of severe plastic deformation.