Large Coefficient Research Articles

A Highly Electrostrictive Salt Cocrystal and the Piezoelectric Nanogenerator Application of Its 3D-Printed Polymer Composite.

Ionic cocrystals with hydrogen bonding can form exciting materials with enhanced optical and electronic properties. We present a highly moisture-stable ammonium salt cocrystal [CH3C6H4CH(CH3)NH2][CH3C6H4CH(CH3)NH3][PF6] ((p-TEA)(p-TEAH)·PF6) crystallizing in the polar monoclinic C2 space group. The asymmetry in (p-TEA)(p-TEAH)·PF6 was induced by its chiral substituents, while the polar order and structural stability were achieved by using the octahedral PF6- anion and the consequent formation of salt cocrystal. The ferroelectric properties of (p-TEA)(p-TEAH)·PF6 were confirmed through P-E loop measurements. Piezoresponse force microscopy (PFM) enabled the visualization of its domain structure with characteristic "butterfly" and hysteresis loops associated with ferro- and piezoelectric properties. Notably, (p-TEA)(p-TEAH)·PF6 exhibits a large electrostrictive coefficient (Q33) value of 2.02 m4 C-2, higher than those found for ceramic-based materials and comparable to that of polyvinylidene difluoride. Furthermore, the composite films of (p-TEA)(p-TEAH)·PF6 with polycaprolactone (PCL) polymer and its gyroid-shaped 3D-printed composite scaled-up device, 3DP-Gy, were prepared and evaluated for piezoelectric energy-harvesting functionality. A high output voltage of 22.8 V and a power density of 118.5 μW cm-3 have been recorded for the 3DP-Gy device. Remarkably, no loss in voltage outputs was observed for the (p-TEA)(p-TEAH)·PF6 devices even after exposure to 99% relative humidity, showcasing their utility under extremely humid conditions.

Effect of Process Parameters on Welding Residual Stress of 316L Stainless Steel Pipe

316L stainless steel pipes are widely used in the storage and transportation of low-temperature media due to their excellent low-temperature mechanical properties and corrosion resistance. However, due to their low thermal conductivity and large coefficient of linear expansion, they often lead to significant welding residual tensile stress and thermal cracks in the weld seam. This also poses many challenges for their secure and reliable applications. In order to effectively control the crack defects caused by stress concentration near the heat-affected zone of the weld, this paper establishes a thermal elastoplastic three-dimensional finite element (FE) model, constructs a welding heat source, and simulates and studies the influence of process parameters on the residual stress around the pipeline circumference and axial direction in the heat-affected zone. Comparison and verification were conducted using simulation and experimental methods, respectively, proving the rationality of the finite element model establishment. The axial and circumferential residual stress distribution obtained by the simulation method did not have an average deviation of more than 30 MPa from the numerical values obtained by the experimental method. This study also considers the effects of welding energy, welding speed, and welding start position on the pipe’s circumferential and axial residual stress laws. The results indicate that changes in welding energy and welding speed have almost no effect on the longitudinal residual stress but have a more significant effect on the transverse residual stress. The maximum transverse residual stress is reached at a welding energy of 1007.4~859.3 J/mm and a welding speed of 6.6 mm/s. Various interlayer arc-striking deflection angles can impact the cyclic phase angle of the transverse residual stress distribution in the seam center, but they do not alter its cyclic pattern. They do influence the amplitude and distribution of the longitudinal residual stress along the circumference. The residual stress distribution on the surface of the pipe fitting is homogenized and improved at 120°.

The impact of food production on ecological footprint in Turkey: an analysis across agriculture, livestock, and aquaculture

AbstractThe ecological footprint (ECF), which has been frequently examined recently, offers a comprehensive analysis of the environment and has started to be used in Turkey. However, although it is a significant area of study in the world, food production, that raise the ECF the most, has not been the subject of much research in Turkey. In the present analysis, food production’s impacts on the ECF in Turkey are analyzed with yearly statistics for the period 1961–2018. Within the frame of this analysis, both food production as a whole and agriculture, livestock, and aquaculture production, which are the components of food, were analyzed individually. In this context, four different models were constructed, and the Autoregressive Distributed Lag method was used to analyze. According to the outcomes of the analysis, food, agriculture, and livestock production raise the ECF while aquaculture production diminishes. The largest coefficient among the three sub-sectors belongs to the agriculture sector. In addition, while the use of fertilizers, agricultural land, GDP, population, and life expectancy at birth increases the ECF, the age dependency ratio decreases, and the effect of rural population differs in the models.

Four-Phonon Enhanced the Thermoelectric Properties of ScSX (X = Cl, Br, and I) Monolayers.

Recently, the FeOCl-type two-dimensional materials have attracted significant attention owing to their versatile applications in fields such as thermoelectricity and photocatalysis. This study aims to systematically investigate the thermoelectric properties of ScSX (X = Cl, Br, and I) monolayers by a combination of the first-principles calculations and the machine-learning interatomic potential approach. These monolayers are indirect semiconductors with band gaps of 3.22 (ScSCl), 3.27 (ScSBr), and 2.87 eV (ScSI), respectively. The lattice thermal conductivity is decreased by 25.72% (20.90%), 44.05% (40.00%), and 30.96% (34.76%) for ScSCl, ScSBr, and ScSI along the x-axis (y-axis) when the four-phonon scattering is introduced, indicating its important role in phonon transport. Anharmonic phonon scattering yields high Grüneisen parameter and scattering rate values, hence causing these low lattice thermal conductivities. Additionally, the large Seebeck coefficients and electrical conductivities of n-type doped ScSX monolayers contribute to their excellent power factors (24.69, 25.66, and 24.99 mW/K2·m for ScSCl, ScSBr and ScSI at 300 K, respectively). Based on the excellent power factor and low thermal conductivity, the maximum values of the figure of merit are calculated to be 2.68, 3.39, and 3.21 for ScSCl, ScSBr, and ScSI monolayers at 700 K, respectively. Our research provides valuable insights into the phonon thermal transport of ScSX monolayers and suggests a promising approach to address high-order anharmonicity.

Kerr coefficient and third-order nonlinear optical absorption coefficient of isotropic diacrylate mesogens at 632.8 nm wavelength

ABSTRACT Third-order optical nonlinearities of diacrylate mesogens RM82 and RM257 in the isotropic phase for a low-power continuous wave laser irradiation at 632.8 nm wavelength have been studied. In their isotropic state, the diacrylate mesogens exhibit quite large nonlinear absorption. We observe a large two-photon absorption coefficients, on an order of 10−6 m/W, for the mesogens. The Kerr coefficients of the mesogens are characterised using single beam Z-scan technique, and found to reach an order of 10−7 m/W. Both diacrylate mesogens exhibit a good material figure of merit.

Spin Caloritronics in Metallic Superlattices.

Spin caloritronics, a research field studying on the interconversion between a charge current (Jc) and a heat current (Jq) mediated by a spin current (Js) and/or magnetization (M), has attracted much attention not only for academic interest but also for practical applications. Newly discovered spin-caloritronic phenomena such as the spin Seebeck effect (SSE) have stimulated the renewed interest in the thermoelectric phenomena of a magnet, which have been known for a long time, e.g. the anomalous Nernst effect (ANE). These spin-caloritronic phenomena involving the SSE and the ANE have provided with a new direction for thermoelectric conversion exploitingJsand/orM. Importantly, the symmetry of ANE allows the thermoelectric conversion in the transverse configuration betweenJqandJc. Although the transverse configuration is totally different from the conventional longitudinal configuration based on the Seebeck effect and has many advantages, we are still facing several issues that need to be solved before developing practical applications. The primal issue is the improvement of conversion efficiency. In the case of ANE-based applications, a material with a large anomalous Nernst coefficient (SANE) is the key for solving the issue. This review article introduces the increase ofSANEcan be achieved by forming superlattice structures, which has been demonstrated for several kinds of materials combinations. The overall picture of studies on spin caloritronics is first surveyed. Then, we mention the pioneering work on the transverse thermoelectric conversion in superlattice structures, which was performed using Fe-based metallic superlattices, and show the recent studies for the Ni-based metallic superlattices and the ordered alloy-based metallic superlattices.

Digital Social Multitasking (DSMT) and Digital Stress Among Adolescents: A Peer Norm Perspective

BackgroundDigital stress refers to the stress resulting from persistent use of digital media. Given its major implications for well-being, it is crucial to explore how the use of digital media would contribute to the stress. Drawing on the frameworks of DSMT (i.e., using a digital device during social interactions) and perceived peer norms, we explored whether and how perceived peer norms of DSMT and adolescents’ own DSMT were associated with digital stress. MethodAdolescents between the ages of 12 and 18 were recruited through the Qualtrics survey panels. A total of 2105 adolescents completed a one-time online survey (Mage = 15.39, S.D. = 1.82). ResultsPath analysis revealed that all three self-DSMT variables (level, positive self-perception, negative self-perception) were associated with higher digital stress, with level and negative self-perception having stronger associations than did positive self-perception. Furthermore, peer DSMT level was related to higher digital stress both directly and indirectly through all three self-DSMT variables. Positive peer perception of DSMT was indirectly related to higher digital stress through higher self-DSMT level and more positive self-perception of DSMT, but was related to lower digital stress through reduced negative self-perception of DSMT. Negative peer perception of DSMT contributed to higher digital stress both directly and indirectly by intensifying teens’ own negative perception of DSMT. Judging from the total-paths coefficients, all three peer norm variables were related to higher digital stress, with level having the largest coefficient, followed by negative peer perception and finally positive peer perception of DSMT. Discussion and ConclusionAll three perceived peer norms of DSMT (level, positive perception, and negative perception) had the potential to increase digital stress directly and/or via impacting teens’ own engagement in and perceptions of DSMT, with perceived peer engagement and negative peer perception being the greater risk factors. At the individual level, a similar pattern emerged—self-DSMT level and negative self-perception had noticeably stronger associations with digital stress than did positive self-perception.

Enhanced thermoelectric performance of W18O49/ZnO composite for waste heat recovery with induced high weighted mobility

Zinc Oxide (ZnO) exhibits a significant Seebeck coefficient, making it a promising candidate for thermoelectric energy harvesting. This study explores composite materials comprising xW18O49/(1-x)ZnO fabricated through conventional sintering at 1150°C, with x varying from 0 to 0.3. Incorporating a highly conductive secondary phase into the ZnO matrix enhances conductivity by 28 times, reaching 111.4 Scm-1 at 800°C, while maintaining 83% of the pristine sample's Seebeck coefficient. Notably, the power factor improves to 3.8 mWK-2m-1 for the x = 0.1 sample, representing a 19 times heightening over unmodified ZnO ceramic. Additionally, these composites exhibit high weight mobility, indicating rapid electronic responses. As a result, the ZT value increases by 500%, reaching 0.15 at 800°C for the x = 1 sample. This study presents a novel approach to fabricating high-power-factor thermoelectric materials by integrating highly conductive oxides into matrices with large Seebeck coefficients.

Accelerated sonochemical fabrication of MIn2S4 (M = Zn, Mg, Ni, Co) for ultra-high photocatalytic hydrogen peroxide production

Ternary metal sulfide (MIn2S4) by virtue of large extinction coefficient, suitable band gap and stability, has been proposed as a candidate for photocatalytic synthesis hydrogen peroxide (H2O2). However, MIn2S4 is conventionally synthesized by solvothermal method that is generally characterized by tedious operational steps and long reaction time. In this work, four sonoMIn2S4 (M = Zn, Mg, Ni, Co) were successfully prepared by sonochemical method within 2 h. These as-synthesized sonoMIn2S4 delivered much high-efficient photocatalytic H2O2 generation. Particularly, the sonoZnIn2S4 presented a H2O2 production rate of 21295.5 μmol∙g−1∙h−1 in water/benzylalcohol system, which is 3.0 times that ZnIn2S4 prepared by solvothermal method. The remarkably improved photocatalytic performance of sonoZnIn2S4 might be due to the multiple defects and fast electron-hole pair separation caused by ultrasound cavitation effect. Other metal sulfide photocatalysts with high performance were efficiently fabricated by facile sonochemical technology as well. The sonochemical method realized the rapid preparation of metal sulfide photocatalysts and efficient production of H2O2, which benefits to meet the United Nations Sustainable Development Goals (SDGs) including SDG-7 and SDG-12.

Assessing satisfaction in simulation among nursing students: psychometric properties of the Satisfaction with Simulation Experience - Italian Version scale

BackgroundThe Satisfaction with Simulation Experience scale is a 5-point Likert scale that measures students’ satisfaction in medium and high-fidelity simulation scenarios. This study aims at investigating the psychometric properties of the Satisfaction with Simulation Experience - Italian Version scale.MethodsA multi-centre cross-sectional study was conducted. The scale was administered to a sample of 266 undergraduate nursing students from two Italian universities after attending a medium- and high-fidelity simulation session in November 2022 and March 2023. Cronbach’s alpha coefficient and item-total correlation were sorted out to assess internal consistency and reliability. The test-retest method was used as a measure of scale stability over time as well as the confirmatory factor analysis to verify construct validity.ResultsThe Cronbach’s alpha value was 0.94 for the overall scale, indicating excellent reliability, and it was 0.84 or higher for each subscales, indicating good reliability. A large correlation coefficient of 0.60 or higher was found between each item and its subscale and between each item and the overall scale score. A medium test-retest correlation coefficient was found for most items (r > 0.30). The confirmatory factor analysis confirmed the factorial structure found in the original study.ConclusionsSatisfaction is an important teaching and learning quality indicator along with the achievement of learning outcomes in simulation. The Satisfaction with Simulation Experience - Italian Version scale showed good reliability and validity; therefore, it could be a useful tool to assess simulation impact in Italian nursing students. The extensive utilization of the Satisfaction with Simulation Experience scale, along with its various validated versions, could facilitate assessing satisfaction in simulation across diverse contexts and enable comparisons of findings across studies in different countries.

Insights into the synergistic effect of polylactam kinetic hydrate inhibitor and amino acid via molecular dynamics simulations

Technological innovation is urgently needed to solve the problem of hydrate formation in oil and gas transmission pipelines for the flow assurance guarantee. Typical kinetic hydrate inhibitors for industrial application are the combination of lactam-based polymers with solvent synergists. In this study, a novel non-solvent synergist leucine (Leu) was proposed for improving the kinetic inhibition effect of polyvinyl caprolactam (PVCap). The synergism of PVCap and Leu was investigated via molecular dynamics simulations. Results showed that the 1 wt% PVCap + 2 wt% Leu system can totally inhibit methane hydrate formation within the simulation period, and the combination systems with other concentrations have negligible effects on delaying hydrate nucleation but can significantly slow down the hydrate growth rate. The excellent synergism of PVCap and Leu may be due to the large diffusion coefficient of the molecules in the systems, which provides a high probability for the aggregation of methane molecules and induces the formation of bubbles. In addition, the bubbles can be further stabilized by the amphiphilic PVCap and Leu molecules around it. This study also provides new insights to develop powerful synergists for PVCap, which would be helpful to the design strategy of KHIs with high efficiency.

London Dispersion Effects on the Structure and Properties of Nonlinear Optical BiB3O6 Crystal.

a-BiB3O6(BiBO) is an important nonlinear optical (NLO) material with high efficiency for applications in harmonic generations and quantum technology. Owing to its low symmetry and cooperative Bi3+lone pair arrangement, it has also exceptional large piezoelectric and electro-optic coefficients and strong anisotropies on other material characteristics. Previous theoretical calculations on its physical properties often gave confusing results. It is found here that London dispersion (LD) tends to stabilize structures with closer packBi3+with large polarizabilities, which is ignored in most previous density functional theory (DFT) calculations. Present study shows that without considering the LD effect, the structure of a-BiB3O6(BiBO) was predicted with an over-estimated (by over 10%) uniqueb-axis while underestimatesaand overestimatescin a less amount. Consequently it is not possible to use the calculated structure to obtain meaningful properties of this important material. By applying a modified post-DFT LD correction,the experimental structure is well reproduced with the theoretical optimized one. Important material property tensors of BiBO crystal are calculated in unprecedented precisions, including: dielectric constants (static and in THz range), elastic and elasto-optic constants, piezoelectric constants, refractive indices, NLO and electro-optic (EO) coefficients.

Nanoimprinting Solution-Derived Barium Titanate for Electro-Optic Metasurfaces.

Electro-optic metasurfaces have demonstrated significant potential in enhancing the modulation speed and efficiency for fast and large-scale free-space optical devices. Barium titanate has a strong electro-optic Pockels coefficient, but its availability in thin-film form is restricted due to costly growth processes or low thickness. Here, we fabricated active metasurfaces using an etch-free bottom-up process with sol-gel-based polycrystalline barium titanate with a large electro-optic coefficient similar to bulk lithium niobate. We achieve strong hybrid Mie/surface lattice resonances with a quality-factor of 200 at 633 nm wavelength, enhancing the light-matter interaction and therefore the Pockels effect. The metasurface transmission is electro-optically modulated with up to 5 MHz driving frequency at low voltages of less than 1 V thanks to resonant enhancement of the modulation amplitude by 2 orders of magnitude. This successful demonstration of electro-optic modulation in nanoimprinted barium titanate structures paves the way for low-cost and large-scale free-space modulators or tunable metalenses.

Strategic white matter hyperintensity locations associated with post-stroke cognitive impairment: a multicenter study in 1568 stroke patients.

Post-stroke cognitive impairment (PSCI) occurs in up to 50% of stroke survivors. Presence of pre-existing vascular brain injury, in particular the extent of white matter hyperintensities (WMH), is associated with worse cognitive outcome after stroke, but the role of WMH location in this association is unclear. We determined if WMH in strategic white matter tracts explain cognitive performance after stroke. Individual patient data from 9 ischemic stroke cohorts with MRI were harmonized through the Meta VCI Map consortium. The association between WMH volumes in strategic tracts and domain-specific cognitive functioning (attention and executive functioning, information processing speed, language and verbal memory) was assessed using linear mixed models and lasso regression. We used a hypothesis-driven design, primarily addressing four white matter tracts known to be strategic in memory clinic patients: the left and right anterior thalamic radiation, forceps major and left inferior fronto-occipital fasciculus. The total study sample consisted of 1568 patients (39.9% female, mean age: 67.3 years). Total WMH volume was strongly related to cognitive performance on all four cognitive domains. WMH volume in the left anterior thalamic radiation was significantly associated with cognitive performance on attention and executive functioning and information processing speed, and WMH volume in the forceps major with information processing speed. The multivariable lasso regression showed that these associations were independent of age, sex, education, and total infarct volume and had larger coefficients than total WMH volume. These results show tract-specific relations between WMH volume and cognitive performance after ischemic stroke, independent of total WMH volume. This implies that the concept of strategic lesions in PSCI extends beyond acute infarcts and also involves pre-existing WMH. The Meta VCI Map consortium is dedicated to data sharing, following our guidelines.

Anomalous thermal transport and high thermoelectric performance of Cu-based vanadate CuVO3

Thermoelectric (TE) conversion technology, capable of transforming heat into electricity, is critical for sustainable energy solutions. Many promising TE materials contain rare or toxic elements, so the development of cost-effective and eco-friendly high-performance TE materials is highly urgent. Herein, we explore the thermal transport and TE properties of transition metal vanadate CuVO3 by using first-principles calculation. On the basis of the unified theory of heat conduction, we uncover the hierarchical thermal transport feature in CuVO3, where wave-like tunneling makes a significant contribution to the lattice thermal conductivity (κl) and results in the anomalously weak temperature dependence of κl. This is primarily attributable to the complex phononic band structure caused by the heterogeneity of Cu–O and V–O bonds. Simultaneously, we report a high power factor of 5.45 mW·K−2·m−1 realized in hole-doped CuVO3, which arises from a high electrical conductivity and a large Seebeck coefficient enabled by the multiple valleys and large electronic density of states near the valence band edge. Impressively, the low κl and the high power factor make p-typed CuVO3 have ZT of up to 1.39, with the excellent average ZT above 1.0 from 300 to 600 K, which is superior to most reported Cu-based TE materials. Our findings suggest that the CuVO3 compound is a promising candidate for energy conversion applications in innovative TE devices.

2D Halide Perovskites for High-Performance Resistive Switching Memory and Artificial Synapse Applications.

Metal halide perovskites (MHPs) are considered as promising candidates in the application of nonvolatile high-density, low-cost resistive switching (RS) memories and artificial synapses, resulting from their excellent electronic and optoelectronic properties including large light absorption coefficient, fast ion migration, long carrier diffusion length, low trap density, high defect tolerance. Among MHPs, 2D halide perovskites have exotic layered structure and great environment stability as compared with 3D counterparts. Herein, recent advances of 2D MHPs for the RS memories and artificial synapses realms are comprehensively summarized and discussed, as well as the layered structure properties and the related physical mechanisms are presented. Furthermore, the current issues and developing roadmap for the next-generation 2D MHPs RS memories and artificial synapse are elucidated.

Ultrahigh-Efficient N,O-Functionalized covalent organic framework towards thorium adsorption from uranium and rare earth elements

The development of novel porous materials as adsorbents for highly effective separation of thorium from ore or nuclear wastewater co-existing with uranium and rare earth elements is one of the most desirable methods but remains challenging. In this work, we prepare a N,O-functionalized two-dimensional covalent organic framework (2D COF), namely TAPT-DHTA, with a permanent porous structure and plenty of nitrogen and oxygen adsorption sites throughout the skeletons, which displays an ultrahigh Th(IV) saturated adsorption capacity of 1394 mg g−1 (at pH = 4.0), higher than all adsorbents reported so far. Moreover, the TAPT-DHTA COF has a large distribution coefficient (Kd) of up to 5.2 × 104 mL g−1, implying its extremely strong affinity for Th(IV) due to the collaborative coordination interactions between N/O atoms and Th(IV) as well as their specific binding mechanism. The distinguished adsorption behavior of the TAPT-DHTA COF affords an important platform for highly selective separation of Th(IV) from uranium and rare earth elements, thereby shedding some light on the design of novel adsorbents for thorium separation in the thorium fuel cycle.

Superconducting nanostrip single photon detectors fabricated of aluminum thin-films

We systematically investigated the detection performance of Al nanostrips for single photons at various wavelengths. The Al films were deposited using magnetron sputtering, and the sophisticated nanostructures and morphology of the deposited films were revealed through high-resolution transmission electron microscopy. The fabricated Al meander nanostrips, with a thickness of 4.2 nm and a width of 178 nm, exhibited a superconducting transition temperature of 2.4 K and a critical current of approximately 5 μA at 0.85 K. While the Al nanostrips demonstrated a saturated internal quantum efficiency for 405-nm photons, the internal detection efficiency exhibited an exponential dependence on bias current without any saturation tendency for 1550-nm photons. This behavior can be attributed to the relatively large diffusion coefficient and coherence length of the Al films. By further narrowing the nanostrip width, the Al-SNSPDs remain capable of effectively detecting single telecom photons to facilitate practical applications.

Phase-change behavior of RuSbTe thin film for photonic applications with amplitude-only modulation.

Ge2Sb2Te5 (GST), the most mature phase-change materials (PCM), functions as a recoding layer in nonvolatile memory and optical discs by contrasting the physical properties upon phase transition between amorphous and crystalline phases. However, GST faces challenges such as a large extinction coefficient (k) and low thermal stability of the amorphous phase. In this study, we introduce RuSbTe as a new PCM to address the GST concerns. Notably, the crystallization temperature of the amorphous RuSbTe is approximately 350 °C, significantly higher than GST. A one-order-of-magnitude increase in the resistivity contrast was observed upon phase transition. The crystalline (0.35-0.50eV) and amorphous (0.26-0.37eV) phases exhibit relatively small band gap values, resulting in substantial k. Although RuSbTe demonstrates a k difference of approximately 1 upon crystallization at the telecommunications C-band, the refractive index (n) difference is negligible. Unlike GST, which induces both phase retardation and amplitude modulation in its optical switch device, RuSbTe exhibits amplitude-only modulation. This study suggests that RuSbTe has the potential to enable new photonic computing devices that can independently control the phase and amplitude. Combining RuSbTe with phase-only modulators could open avenues for advanced applications.

Effect of shells number and machining on selected properties of 3D-printed PLA samples

Effect of shells number (1–5) on tensile properties of PLA samples printed using the FDM/FFF technique was investigated. The crack surface was also analyzed. The best properties were obtained for 4-shell sample. However, due to the large coefficient of variation (>> 10%) in the case of elongation, 3-shell sample was selected for testing the machining impact. Such a large coefficient of variation can be explained by the presence of voids between the layers. The greater the number of layers, the greater the structure defects. Machining increases surface smoothness while reducing tensile strength and practically unchanged elongation at break.