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Noncovalent interactions and properties of host–guest systems based on C82/C82Gd bucky-balls and symmetry broken nanohoop TP-[11]CPP
The nanoscale host–guest interactions between a symmetry broken carbonaceous nanohoop TP-[11]cycloparaphenylene (TP-[11]CPP) and endohedral metallofullerene (EMF) C82Gd were explored by using density functional theory calculations. The geometry mutual-matching between TP-[11]CPP and C82Gd is perfect, and the two main configurations of TP-[11]CPP@C82Gd host–guest complexes could be formed spontaneously with high binding energies. Interestingly, the position of the Gd atom in the C82 cage can be adjusted by its external host molecule. The binding strength depends on the structure of the host, but the binding thermodynamics is decided by the structure of the fullerene cage. The selective binding of empty cage C82 from its mixture with EMF C82Gd is discussed by using a standard Boltzmann expression of statistical thermodynamics. In addition, the FT-IR and UV–visible spectra are simulated, host–guest noncovalent interaction regions are investigated based on the electron density and reduced density gradient, and magnetic susceptibility is preliminarily investigated, which may be helpful for a deep understanding of the present host–guest systems in the future. It is anticipated that such a theoretical calculation regarding to carbonaceous nanosize host–guest structures would be a driven force for the developments of novel nanohoop@EMF systems in functional materials, nonchromatographic separation and even nano single molecular electret devices.
Multivariate Gaussian Bayes classifier with limited data for segmentation of clean and contaminated regions in the small bowel capsule endoscopy images
A considerable amount of undesirable factors in the wireless capsule endoscopy (WCE) procedure hinder the proper visualization of the small bowel and take gastroenterologists more time to review. Objective quantitative assessment of different bowel preparation paradigms and saving the physician reviewing time motivated us to present an automatic low-cost statistical model for automatically segmenting of clean and contaminated regions in the WCE images. In the model construction phase, only 20 manually pixel-labeled images have been used from the normal and reduced mucosal view classes of the Kvasir capsule endoscopy dataset. In addition to calculating prior probability, two different probabilistic tri-variate Gaussian distribution models (GDMs) with unique mean vectors and covariance matrices have been fitted to the concatenated RGB color pixel intensity values of clean and contaminated regions separately. Applying the Bayes rule, the membership probability of every pixel of the input test image to each of the two classes is evaluated. The robustness has been evaluated using 5 trials; in each round, from the total number of 2000 randomly selected images, 20 and 1980 images have been used for model construction and evaluation modes, respectively. Our experimental results indicate that accuracy, precision, specificity, sensitivity, area under the receiver operating characteristic curve (AUROC), dice similarity coefficient (DSC), and intersection over union (IOU) are 0.89 ± 0.07, 0.91 ± 0.07, 0.73 ± 0.20, 0.90 ± 0.12, 0.92 ± 0.06, 0.92 ± 0.05 and 0.86 ± 0.09, respectively. The presented scheme is easy to deploy for objectively assessing small bowel cleansing score, comparing different bowel preparation paradigms, and decreasing the inspection time. The results from the SEE-AI project dataset and CECleanliness database proved that the proposed scheme has good adaptability.
Symmetry breaking-induced resonances with more efficient terahertz reflections
We report our experimental observation and theoretical and numerical validation of a new type of THz resonance and bandgap induced by symmetry breaking in a periodically corrugated parallel plate waveguide. Unlike the familiar Bragg resonances, the observed unusual resonance is found to result from the strong interaction between THz wave modes with different transverse standing-wave profiles that occurs far away from the edges of the Brillouin zone. Unexpectedly, such resonance depends strongly on the mirror symmetry of the waveguide and can produce exceptionally strong power attenuation and a wider and steeper frequency bandgap for THz waves. THz bandgap properties of waveguides with different symmetries can be identified unambiguously by the simulated dispersion diagrams, electric fields, and mode analysis. Symmetry breaking-induced THz resonances will not only benefit the understanding of wave propagation in complex waveguides but also open a new pathway to design more complex band structures in applications such as high-speed communications.
A new apparatus for gas-phase low temperature kinetics study: Kinetics measurement and product detection of the CH + propene reaction at 23 K
We have developed a novel instrument to study reaction kinetics of astrochemical interest at low temperatures. This setup integrates laser-induced fluorescence (LIF) and vacuum ultraviolet (VUV) photoionization reflectron time-of-flight mass spectrometry (ReTOFMS) with a supersonic uniform low-temperature flow. A pulsed helium Laval nozzle with a Mach number of 6 was employed, achieving a temperature of 23 ± 3 K and a density of (2.0 ± 0.4) × 1016 molecule cm−3. The second-order rate coefficient for the reaction between the methylidyne radical (CH) and propene (C3H6) at 23(3) K was determined to be (3.4 ± 0.6) × 10−10 cm3 molecule−1 s−1 using LIF kinetics measurements. VUV (118.27 nm) photoionization ReTOFMS detected a dominant product channel, CH + C3H6 → C4H6 + H, without isomer identification. Another less intense mass peak at m/z 53 was also observed, which could either result from the dissociative ionization of the energized C4H6 primary products or indicate another product channel, C4H5 + H2. Given the presence of CH and C3H6 in cold molecular clouds (e.g., TMC-1, Lupus-1a, L1495B, L1521F, and Serpens South 1a), it is predicted that these products can exist in low-temperature interstellar environments.
Trace metals and their human health risks in sesame seeds from the main cultivation areas of Ethiopia
Sesame (Sesamum indicum L.) is a major oilseed crop globally, and white sesame is a key contributor to the foreign exchange earnings of Ethiopia. The main production districts of white sesame in Ethiopia are Humera, Metema, Tegedie, Mirab-Armachiho and Tachi-Armaciho. This study assessed the levels of trace metals (Fe, Cu, Zn, Mn and Ni) in white sesame seeds from these regions and evaluated the associated health risks to consumers. A total of 53 samples were collected from 19 farmer villages across the five districts. Homogenized samples from each village were analyzed using the acid digestion method followed by flame atomic absorption spectroscopy (FAAS). The limit of detection of the method ranged from 0.75 to 865 mg/kg, and the limit of quantitation ranged from 2.55 to 28.8 mg/kg for the different elements analyzed. The recovery of the method was in the range of 90.9‒99.6%. The results showed trace metal levels ranging from 164 ± 6 to 381 ± 4 mg/kg for Fe, 94.0 ± 1.9 to 126 ± 0.8 mg/kg for Zn, 11.8 ± 0.4 to 14.2 ± 0.4 mg/kg for Cu, 11.9 ± 0.9 to 15.0 ± 0.7 mg/kg for Mn and 16.2 ± 1.1 to 21.0 ± 1.2 mg/kg for Ni across the production districts. One-way ANOVA revealed significant differences (p < 0.05) in trace metal concentrations among the districts, indicating a geographical effect on the trace metal content of sesame. Importantly, the study found no non-carcinogenic health risks from the analyzed metals for either adult or child consumers. These findings suggest that the trace metal levels in the sesame seeds are within safe limits for human consumption.
Synergistic effect of Fe etching and Ar+ bombardment on the electron field emission properties of single-crystal diamond
A new strategy coupling Fe etching with Ar+ bombardment was proposed and carried out on the single-crystal diamond (SCD) surface for enhancing the electrical properties of diamond by the dual effects of defects and impurity elements. Scanning electron microscope, energy dispersive x-ray spectrum, x-ray diffractometer, Raman spectroscopy, and Hall effects measurements were performed to investigate the modified surface structure and electron field emission (EFE) performance. The results indicated that concentric circle patterns accompanying propitious clouds were generated after the treatment, which were composed of nano-sized carbides including FeC, WC, W2C, and Fe3W3C, respectively. The Hall mobility and carrier concentration of the treated SCD were about 22.55 cm2 V−1 s−1 and 2.71 × 1021 cm−3, which are 12 times and 4 orders of magnitude higher than the pristine SCD, respectively. The EFE behavior was turned on at E0 = 6.2 V/μm, achieving a current density of 6.8 mA/cm2 at the applied field of 10 V/μm. The present study offers the possibility of using SCD as EFE material and an effective method for enhancing the EFE properties of diamond.
27Al NMR spectroscopic and DFT computational study of the quadrupole coupling of aluminum in two polymorphs of the complex aluminum hydride CsAlH4
The quadrupole coupling constant CQ and the asymmetry parameter η of the aluminum nuclei in two polymorphs of the complex aluminum hydride CsAlH4 are determined from both 27Al magic-angle spinning (MAS) nuclear magnetic resonance (NMR) spectra and 27Al NMR spectra recorded for stationary samples by using the Solomon echo sequence. The accuracy with which these parameters can be determined from the static spectra [CsAlH4(o): CQ = (1.42 ± 0.01) MHz, η = (0.62 ± 0.01) and CsAlH4(t): CQ = (1.43 ± 0.02) MHz, η &lt; 0.03] seems to be slightly higher than via the MAS approach. The experimentally determined parameters (δiso, CQ, and η) are compared with those obtained from DFT-GIPAW (density functional theory—gauge-including projected augmented wave) calculations. When using DFT-optimized structures, the magnitude of the quadrupole coupling constant is overestimated by about 45% for both polymorphs. Further calculations in which the geometry of the AlH4 tetrahedra is varied show a high sensitivity of CQ to the H–Al–H angles. Modest changes in the angles on the order of one to three degrees are sufficient to achieve a near-perfect agreement between GIPAW calculations and experiments. The deviations found for the DFT-optimized structures are explained with the neglect of thermal motion, which typically leads to a reduction in the distortion of the AlH4 tetrahedra. From a broader perspective, the uncertainty in the positions of the hydrogen atoms renders the accurate reproduction or prediction of quadrupole coupling constants for aluminum hydrides challenging.
Algorithm, expert, or both? Evaluating the role of feature selection methods on user preferences and reliance
The integration of users and experts in machine learning is a widely studied topic in artificial intelligence literature. Similarly, human-computer interaction research extensively explores the factors that influence the acceptance of AI as a decision support system. In this experimental study, we investigate users’ preferences regarding the integration of experts in the development of such systems and how this affects their reliance on these systems. Specifically, we focus on the process of feature selection—an element that is gaining importance due to the growing demand for transparency in machine learning models. We differentiate between three feature selection methods: algorithm-based, expert-based, and a combined approach. In the first treatment, we analyze users’ preferences for these methods. In the second treatment, we randomly assign users to one of the three methods and analyze whether the method affects advice reliance. Users prefer the combined method, followed by the expert-based and algorithm-based methods. However, the users in the second treatment rely equally on all methods. Thus, we find a remarkable difference between stated preferences and actual usage, revealing a significant attitude-behavior-gap. Moreover, allowing the users to choose their preferred method had no effect, and the preferences and the extent of reliance were domain-specific. The findings underscore the importance of understanding cognitive processes in AI-supported decisions and the need for behavioral experiments in human-AI interactions.
Depth-resolved measurements of magnetic domains in grain-oriented electrical steel
A new method for obtaining depth-resolved measurements with an x-ray magnetic circularly polarized emission (XMCPE) microscope is reported in this work. Depth-resolved observations of magnetic domains well below the surface of thick opaque specimens are important for industrial applications. XMCPE is a suitable technique for this purpose because of its long penetration length and large magnetic dichroic effect. Utilizing the proposed method, a confocal microscope is constructed, and several cross-sectional images of magnetic domains of grain-oriented electrical steel are obtained to demonstrate the performance of the developed depth-resolved microscope. A single component of the magnetization vector is surveyed. The spatial resolution of the microscope is estimated to be ≈10μm.
Accurate and efficient prediction of double excitation energies using the particle–particle random phase approximation
Double excitations are crucial to understanding numerous chemical, physical, and biological processes, but accurately predicting them remains a challenge. In this work, we explore the particle–particle random phase approximation (ppRPA) as an efficient and accurate approach for computing double excitation energies. We benchmark ppRPA using various exchange-correlation functionals for 21 molecular systems and two point defect systems. Our results show that ppRPA with functionals containing appropriate amounts of exact exchange provides accuracy comparable to high-level wave function methods such as CCSDT and CASPT2, with significantly reduced computational cost. Furthermore, we demonstrate the use of ppRPA starting from an excited (N − 2)-electron state calculated by ΔSCF for the first time, as well as its application to double excitations in bulk periodic systems. These findings suggest that ppRPA is a promising tool for the efficient calculation of double and partial double excitation energies in both molecular and bulk systems.
Technology-enabled hybrid cardiac rehabilitation: Qualitative study of healthcare professional and patient perspectives at three cardiac rehabilitation centres in England
Coronary heart disease (CHD) is a leading cause of death in the UK. Clinical guidelines recommend cardiac rehabilitation (CR), including health education, cardiovascular risk reduction advice, physical activity and stress management components. However, uptake of standard in-person, group-based CR is only around 50%. Hybrid cardiac rehabilitation (CR), combining in-person and remote service delivery, may improve CR uptake and reduce inequalities in service access. This study used focus groups and semi-structured interviews to explore staff and patient experiences of using the Active+me REMOTE hybrid CR app, a cloud-based platform providing access to education modules, behaviour change support, live exercise classes, physical activity and health monitoring across three sites in the East of England. Twelve staff and six patients participated. Topic guides explored participants’ experiences of delivering or receiving hybrid CR, barriers and facilitators associated with the hybrid CR pathway, and implications for future implementation of Active+me REMOTE. Qualitative data were collected remotely, audio-recorded and independently transcribed. Staff data were analysed deductively, using the Consolidated Framework for Implementation Research (CFIR). Patient data were analysed inductively using thematic analysis. Despite some technical issues and governance delays, Active+me REMOTE was perceived as acceptable, convenient and allowed tailoring of support to meet patients’ needs and circumstances. Data upload from wearable devices (blood pressure monitors) allowed staff to monitor patients’ progress and empowered patients to direct their recovery. Staff initially felt they should screen patients to ensure that hybrid CR was offered to digitally literate, physically active individuals, although screening became less common as staff familiarity with the app increased. Findings suggest that effective implementation of hybrid CR requires system-level resource to facilitate governance approvals and embed hybrid CR delivery as standard care. Sufficient time must be allowed for staff training and to support patient enrolment to hybrid services. The study was registered on 3/7/2023 (ISRCTN320764).
Comparative study of doping properties and the effect on sliding barriers in γ-InSe
As the sliding ferroelectricity (SF) emerges as a potential approach to develop low-power ferroelectric electronics, fabricating high-quality SF van der Waals (vdW) crystals is of great importance. For the SF material γ-InSe, doping with proper elements has been verified to be an effective method to suppress the stacking faults and stabilize polarization. However, the underlying mechanism has not been understood, and the rule to select the proper doping elements remains unclear. Herein, using first-principles simulations, we perform a comparative study on the doping effects of several elements on γ-InSe, including Y, Dy, Bi, Sn, and Er. Interstitials in the vdW gap and substitutional antisites are found to be the most probable defects introduced by doping. Interestingly, the substitutional defects (, SnIn, ErIn, BiIn, and BiSe) are found to weaken the strength of interlayer coupling, leading to the decreased sliding barriers, while the interstitials defects (Yi1 and Dyi1) are found to enhance the sliding barriers. Naturally, we propose that the interstitials in the vdW gap can suppress stacking faults, while the substitutional defects do not have this effect. The experimental comparation of typical InSe:Y and InSe:Bi, with the highest and lowest predicted sliding barriers, respectively, aligns well with our proposed mechanism. This work provides a new theoretical approach to determine the proper doping elements for high-quality SF materials.
A new determination of group-modified pore size distribution of activated carbon from confined density distribution
The two-distribution model is developed to determine the group-modified pore size distribution (PSD) of activated carbon, where the PSD is modified by the group distribution. This model assumes an ensemble composed of the elementary confined density distribution for fluids and the group-modified PSD for activated carbon. The group-modified PSD is derived by fitting the theoretical adsorption, calculated using the two-distribution model with grand canonical Monte Carlo simulation-dependent kernels of the N2 isotherm at 77.4 K and a single CO2 adsorption data point at 273.0 K, to experimental adsorption data for activated carbon. The group-modified PSD is validated against adsorption data for seven fluids on various activated carbons. In this analysis, the adsorption isotherms calculated using the two-distribution model with PSD, homogeneous group-modified PSD, and inhomogeneous group-modified PSD are compared and evaluated. The results show that the two-distribution model accurately interprets the group-modified PSD.
Acceptability and feasibility of acceptance and commitment therapy for improving outcomes in hematopoietic stem cell transplant
Introduction: Allogeneic hematopoietic stem cell transplant (HCT) has the potential to cure patients with hematologic malignancies, but treatment-related morbidity and mortality is high. Transplant outcomes are optimized by patients maintaining physical activity. The aim of the current study was to examine whether a brief Acceptance and Commitment Therapy (ACT) intervention is acceptable to HCT patients and caregivers and helps patients engage in healthy behavior despite physical and emotional discomfort. Methods: Patients ≥ 18 years of age who were undergoing allogenic HCT for any cancer or non-cancer illness and their caregivers were invited to complete six ACT sessions between transplant day − 30 and day + 90. Multiple small cohorts of n = 3 dyads were enrolled, and the protocol content was iterated after each cohort to reflect the experiences and breadth of concerns of individuals undergoing HCT. Acceptability was indexed by session completion rates and acceptability surveys. Pre-post 6-minute walk distance was collected as an index of physical function as part of standard care. Results: Sixteen HCT dyads enrolled in the study; 12 continued to treatment. Most participants completed all assigned sessions. Participants perceived ACT to be helpful and 70% (5 of 7) of the patients with pre-post 6-minute walk test data showed improvement. Conclusion: ACT is an acceptable and potentially useful intervention for individuals undergoing HCT. Additional controlled studies are warranted.
Unified description of electron spin relaxation in (110)-oriented III–V semiconductor quantum wells
III–V semiconductor quantum wells (QWs) with (110) orientation are expected to serve as a platform for spintronic devices due to their ability to exhibit prolonged electron spin-relaxation times to the order of nanoseconds even at room temperature. Although various spin-relaxation mechanisms have been proposed and the spin-relaxation time has been discussed qualitatively, quantitative clarification of the contribution of each mechanism is crucial. In this study, we demonstrate that the electron spin-relaxation times calculated as a function of quantized energy, temperature, and electron density in GaAs/AlGaAs (110) QWs, accounting for all potential spin-relaxation mechanisms (Elliott–Yafet, intersubband spin relaxation, and exciton spin relaxation), show good agreement with experimental data. Our results reveal that the contribution of each spin-relaxation mechanism to the total spin-relaxation time in the (110) QWs can be quantitatively identified and that the dominant mechanism depends on the specific conditions. These findings will facilitate the design of suitable QW structures for spintronic devices and enable precise estimation of the spin-relaxation time under operating conditions of (110) QW-based spintronic devices.
Accuracy of charge densities in electronic structure calculations
Accurate charge densities are essential for reliable electronic structure calculations because they significantly impact predictions of various chemical properties and, in particular, according to the Hellmann–Feynman theorem, atomic forces. This study examines the accuracy of charge densities obtained from different density functional theory (DFT) exchange–correlation functionals in comparison with coupled cluster calculations with single and double excitations. We find that modern DFT functionals can provide highly accurate charge densities, particularly in case of meta-generalized gradient approximations and hybrid functionals. In connection with Gaussian basis sets, it is necessary to use the largest basis sets available to obtain densities that are nearly free of basis set errors. These findings highlight the importance of selecting appropriate computational methods for generating high-precision charge densities, which are, for instance, needed to generate reference data for training modern machine learned potentials.
Investigating the dynamics of climate finance disbursements: A panel data approach from 2003 to 2022
This study investigates the intricate dynamics of international multilateral climate finance disbursements from 2003 to 2022 via an extensive dataset from the Climate Funds Update (CFU). By employing panel data econometric models, including pooled ordinary least squares (OLS), fixed effects (FE), and random effects (RE) models, the study elucidates the impact of grants and approved funds on disbursement levels across different income groups. The analysis reveals that while grants do not significantly influence disbursements, the approval of funds plays a critical role in enhancing disbursement efficiency. The random effects model, validated through the Hausman test, emerges as the optimal model for this context. The findings underscore the importance of streamlined approval processes in ensuring effective climate finance disbursements and highlight the need for further investigation into the non-significance of grants. The forecasting results indicate a positive trend in disbursements from 2023 to 2027, with potential fluctuations driven by external factors. This study provides valuable insights for policymakers and stakeholders to optimize climate finance mechanisms and improve fund utilization for sustainable development.
Reflectometry technique for study of complex multilayer micro- and nanostructures with lateral periodicity
This study introduces a reflectometry-based technique for characterizing complex thin-film structures with lateral periodicity, using only a single, large-beam measurement to capture essential structural information. The PillarHall test chip structure, selected as a case study, features an air gap of 500 nm nominal thickness inside a layer structure with periodically repeated lateral structure elements. Using a non-destructive reflectometry technique, the sample's layer structure was analyzed through spectral reflectance measurements, conducted with a Cary 7000 spectrometer, and processed with a dedicated MATLAB code that incorporates the transfer matrix method to model and fit the reflectance spectrum. Two models, a basic and an advanced four-layer model, were developed and tested by fitting the simulated reflectance spectrum to a measured one. While the basic model provides sufficient information about the thin-film structure, the advanced model considers detailed variations in the thickness across the sample caused by specific structural features. Reflectometry results on structural sizes agree with direct profilometry measurements, supporting the method’s reliability. These findings demonstrate that a single, large-beam measurement can yield comprehensive insights, positioning reflectometry as a robust tool for the advanced thin-film characterization of complex periodic structures.
Chiral transfers and chiral switching in bilayer of vanadyl phthalocyanine
Chiral transfer and chiral switch in the bilayer of achiral vanadyl phthalocyanine (VOPc) on Cd(0001) have been investigated with low temperature scanning tunneling microscopy (STM). In the monolayer regime, the VOPc molecules form a self-assembled layer consisting of periodic chiral voids. Further deposition of VOPc leads to the bilayer formation with an O-up top layer and an O-down bottom layer. High-resolution STM images demonstrate that not only single-molecule chirality but also organizational chirality is transferred from the underlying chiral voids to the top layer. The organizational chirality of the top layer manifests as chiral windmill protrusions, distinct from the chiral voids of the bottom layer. After annealing the bilayer to 310 K, strain is relaxed in the form of a mass density wave (MDW). In particular, the organizational chirality inside MDW domains is opposite to that outside the domains, indicating a chiral switch takes place after the strain relaxation.
Point-of-interest recommender model using geo-tagged photos in accordance with imperialist Fuzzy C-means clustering
Although recommender systems (RSs) strive to provide recommendations based on individuals’ histories and preferences, most recommendations made by these systems do not utilize location and time-based information. This paper presents a travel recommender system by integrating the Imperialist Competitive Algorithm (ICA) and Fuzzy C-Means (FCM) Clustering algorithm. Compared to similar studies, this recommender system takes into account more POIs, including location, number of visits, weather conditions, time of day, user mood, traffic volume, season, and temperature. The effectiveness and accuracy of the proposed method are assessed using the Flickr dataset, indicating that it is able to provide effective and accurate recommendations that are compatible with the user’s interests and the current status of his/her visit. Results showed that, precision and Mean Absolute Precision (MAP) in the proposed method have been grown 23.6% and 23.72% in comparison to Popularity Rank, 28.98% and 19.67% in comparison to Classic Rank and 18.66% and 19.67% in comparison to Frequent Rank methods. Also, Mean Absolute Error (MAE) index in proposed method has been improved 60.71%, 64.51% and 56% in comparisons to the Popularity Rank, Classic Rank and Frequent Rank methods respectively.