Abstract
Atom-thick van der Waals heterostructures with nontrivial physical properties tunable via the magnetoelectric coupling effect are highly desirable for the future advance of multiferroic ...devices. In this work on LaCl/In
2
Se
3
heterostructure consisting of a 2D ferromagnetic layer and a 2D ferroelectric layer, reversible switch of the easy axis and the Curie temperature of the magnetic LaCl layer has been enabled by switching of ferroelectric polarization in In
2
Se
3
. More importantly, magnetic skyrmions in the bimerons form have been discovered in the LaCl/In
2
Se
3
heterostructure and can be driven by an electric current. The creation and annihilation of bimerons in LaCl magnetic nanodisks were achieved by polarization switching. It thus proves to be a feasible approach to achieve purely electric control of skyrmions in 2D van der Waals heterostructures. Such nonvolatile and tunable magnetic skyrmions are promising candidates for information carriers in future data storage and logic devices operated under small electrical currents.
Piezoelectric materials, which respond mechanically to applied electric field and vice versa, are essential for electromechanical transducers. Previous theoretical analyses have shown that high ...piezoelectricity in perovskite oxides is associated with a flat thermodynamic energy landscape connecting two or more ferroelectric phases. Here, guided by phenomenological theories and phase-field simulations, we propose an alternative design strategy to commonly used morphotropic phase boundaries to further flatten the energy landscape, by judiciously introducing local structural heterogeneity to manipulate interfacial energies (that is, extra interaction energies, such as electrostatic and elastic energies associated with the interfaces). To validate this, we synthesize rare-earth-doped Pb(Mg
Nb
)O
-PbTiO
(PMN-PT), as rare-earth dopants tend to change the local structure of Pb-based perovskite ferroelectrics. We achieve ultrahigh piezoelectric coefficients d
of up to 1,500 pC N
and dielectric permittivity ε
/ε
above 13,000 in a Sm-doped PMN-PT ceramic with a Curie temperature of 89 °C. Our research provides a new paradigm for designing material properties through engineering local structural heterogeneity, expected to benefit a wide range of functional materials.
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IJS, KISLJ, NUK, SBMB, UL, UM, UPUK
The organic nitroxyl radical, TEMPO (2,2,6,6-tetramethylpiperidine-N-oxyl), finds a variety of industrial applications for chemical transformations. Because of economic and environmental concerns, ...the recovery and reuse of TEMPO with maintained high activity are of the utmost importance. In this Review, we summarize the most important advances made by the scientific community in TEMPO immobilization on various organic and inorganic support materials for recovery and reuse, and we discuss the activity and stability, as well as the procedures. Also summarized is the wide range of applications of TEMPO in both homogeneous and heterogeneous forms in chemical transformations, beginning from methodology tuning in synthetic chemistry to the use in polymer chemistry.
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IJS, KILJ, NUK, PNG, UL, UM
The discovery of ultrahigh piezoelectricity in relaxor-ferroelectric solid solution single crystals is a breakthrough in ferroelectric materials. A key signature of relaxor-ferroelectric solid ...solutions is the existence of polar nanoregions, a nanoscale inhomogeneity, that coexist with normal ferroelectric domains. Despite two decades of extensive studies, the contribution of polar nanoregions to the underlying piezoelectric properties of relaxor ferroelectrics has yet to be established. Here we quantitatively characterize the contribution of polar nanoregions to the dielectric/piezoelectric responses of relaxor-ferroelectric crystals using a combination of cryogenic experiments and phase-field simulations. The contribution of polar nanoregions to the room-temperature dielectric and piezoelectric properties is in the range of 50-80%. A mesoscale mechanism is proposed to reveal the origin of the high piezoelectricity in relaxor ferroelectrics, where the polar nanoregions aligned in a ferroelectric matrix can facilitate polarization rotation. This mechanism emphasizes the critical role of local structure on the macroscopic properties of ferroelectric materials.
Common mental health problems (CMHPs), such as depression, anxiety disorder, obsessive-compulsive disorder (OCD), and post-traumatic stress disorder (PTSD) are internalizing disorders with high ...comorbidity. University and college students are under many stressors and transitional events, and students fall within the age range when CMHPs are at their developmental peak. Compared to the expanded effort to explore and treat CMHPs, there has been no a meta-analysis that comprehensively reviewed the interventions for CMHPs and examined the effects of interventions for CMHPs in college students. The objective of this review is to conduct a systematic review and meta-analysis of randomized controlled trials (RCTs) examining interventions for CMHPs among university and college students and to estimate their post-intervention effect size (ES), as well as follow-up ES, for depression, anxiety disorder, OCD and PTSD separately. Meta-analytic procedures were conducted in accordance with PRISMA guidelines. We reviewed 7768 abstracts from which 331 full-text articles were reviewed and 51 RCTs were included in the analysis. We found moderate effect sizes for both depression (Hedges' g = −0.60) and anxiety disorder (Hedges' g = −0.48). There was no evidence that existing interventions for OCD or PTSD were effective in this population. For interventions with high number of papers, we performed subgroup analysis and found that cognitive behavioral therapy (CBT) and mindfulness-based interventions were effective for both depression and generalized anxiety disorder (GAD), and attention/perception modification was effective for GAD; other interventions (i.e. art, exercise and peer support) had the highest ES for both depression and GAD among university and college students.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Escherichia coli is generally used as model bacteria to define microbial cell factories for many products and to investigate regulation mechanisms. E. coli exhibits phospholipids, ...lipopolysaccharides, colanic acid, flagella and type I fimbriae on the outer membrane which is a self-protective barrier and closely related to cellular morphology, growth, phenotypes and stress adaptation. However, these outer membrane associated molecules could also lead to potential contamination and insecurity for fermentation products and consume lots of nutrients and energy sources. Therefore, understanding critical insights of these membrane associated molecules is necessary for building better microbial producers. Here the biosynthesis, function, influences, and current membrane engineering applications of these outer membrane associated molecules were reviewed from the perspective of synthetic biology, and the potential and effective engineering strategies on the outer membrane to improve fermentation features for microbial cell factories were suggested.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
High-performance lead-free piezoelectric materials are in great demand for actuator applications replacing the mainstay Pb(Zr, Ti)O3 materials. In this research, pseudo-cubic 0.64BiFeO3–0.36BaTiO3 ...(0.64BF–0.36BT) lead-free ceramics were studied, exhibiting high electric-field-induced strain of 0.38% (60 kV/cm) with large signal piezoelectric coefficient d33* of 720 pm/V (40 kV/cm) and low strain hysteresis of 8% at 150 °C. It is important that the strain (40 kV/cm) of prototypic co-fired multilayer actuator is found to increase from 0.22% to 0.3% at elevated temperature of 150 °C, accompanied by a significantly decreased strain hysteresis. The behind mechanism of the large unipolar strain was investigated by in-situ synchrotron powder X-ray diffraction under different electric fields, being analogous to (Bi, Na)TiO3-BaTiO3 based ceramics but different from Pb(Zr,Ti)O3 based counterparts. An evident transition from pseudo-cubic to rhombohedral phase was triggered above electric field of 10 kV/cm, where the lattice distortion, domain switching and phase transition synergistically contribute to the observed large macrostrain. These results demonstrate that the lead-free BiFeO3–BaTiO3 ferroelectric ceramics with pseudo-cubic phase have great potential for high temperature actuator applications.
(a) Unipolar S–E curves of 0.64BF–0.36BT ceramics under different electric fields, (b) {222}PC reflections with the increase of electric field. Pseudo-cubic 0.64BF–0.36BT lead-free ceramics were studied, exhibiting high electric-field-induced strain of 0.38% (60 kV/cm) with large signal piezoelectric coefficient d33* of 720 pm/V (40 kV/cm), being about 40% higher than those of other representative BF-based ternary ceramics. An evident transition from pseudo-cubic to rhombohedral phase was triggered above electric field of 10 kV/cm, where the lattice distortion, domain switching and phase transition synergistically contribute to the observed large macrostrain. Display omitted
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Single-atom catalysts (SACs) have attracted considerable attention in the catalysis community. However, fabricating intrinsically stable SACs on traditional supports (N-doped carbon, metal oxides, ...etc.) remains a formidable challenge, especially under high-temperature conditions. Here, we report a novel entropy-driven strategy to stabilize Pd single-atom on the high-entropy fluorite oxides (CeZrHfTiLa)O
(HEFO) as the support by a combination of mechanical milling with calcination at 900 °C. Characterization results reveal that single Pd atoms are incorporated into HEFO (Pd
@HEFO) sublattice by forming stable Pd-O-M bonds (M = Ce/Zr/La). Compared to the traditional support stabilized catalysts such as Pd@CeO
, Pd
@HEFO affords the improved reducibility of lattice oxygen and the existence of stable Pd-O-M species, thus exhibiting not only higher low-temperature CO oxidation activity but also outstanding resistance to thermal and hydrothermal degradation. This work therefore exemplifies the superiority of high-entropy materials for the preparation of SACs.
With the successful application of the Shack–Hartmann wavefront sensor in measuring aberrations of the human eye, researchers found that, when the aberration is large, the local wavefront distortion ...is large, and it causes the spot corresponding to the sub-aperture of the microlens to shift out of the corresponding range of the sub-aperture. However, the traditional wavefront reconstruction algorithm searches for the spot within the corresponding range of the sub-aperture of the microlens and reconstructs the wavefront according to the calculated centroid, which leads to wavefront reconstruction errors. To solve the problem of the small dynamic range of the Shack–Hartmann wavefront sensor, this paper proposes a wavefront reconstruction algorithm based on the autocorrelation method and a neural network. The autocorrelation centroid extraction method was used to calculate the centroid in the entire spot map in order to obtain a centroid map and to reconstruct the wavefront by matching the centroid with the microlens array through the neural network. This method breaks the limitation of the sub-aperture of the microlens. The experimental results show that the algorithm improves the dynamic range of the first 15 terms of the Zernike aberration reconstruction to varying degrees, ranging from 62.86% to 183.87%.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
► Heat transfer and pressure drop of nanofluids in laminar flow are studied. ► Friction factor is in good agreement with the Hagen-Poiseuille theory. ► Heat transfer of nanofluids is considerably ...enhanced at high Reynolds number. ► Particle migration and shear thinning behavior tend to flatten velocity profile. ► Dilute nanofluids containing carbon nanotubes are promising heat transfer media.
The heat transfer and pressure drop of nanofluids containing carbon nanotubes in a horizontal circular tube are experimentally investigated. The friction factor of the dilute nanofluids shows a good agreement with the prediction from the Hagen-Poiseuille flow theory. A considerable enhancement in the average convective heat transfer is also observed compared with the distilled water. For the nanofluids with volumetric concentration of 0.05% and 0.24%, the heat transfer enhancement are 70% and 190% at Reynolds number of about 120 respectively, while the enhancement of thermal conductivity is less than 10%, therefore, the large heat transfer increase cannot be solely attributed to the enhanced thermal conductivity. By measuring the pump power supply and the thermal conductance of the test tube, our results suggest that the nanofluids at low concentration enhance the heat transfer with little extra penalty in pump power, thus have great potential for applications in the heat transfer systems.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
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