Giant dielectric tunability in ferroelectric ceramics with ultralow loss by ion substitution design.

Due to their responsiveness to modulation by external direct current fields, dielectric tunable materials are extensively utilized in integrated components, such as ferroelectric phase shifters. Barium strontium titanate ceramics have been considered the most potential tunable materials for a long time. However, the significant dielectric loss and high voltage drive have limited their further applications. Recently, Bi6Ti5WO22 ceramic has regained attention for its high dielectric tunability with low loss. In this study, we judiciously introduce Nb5+ with a larger ionic radius, replacing Ti4+ and W6+. This successful substitution enables the modulation of the phase transition temperature of Bi6Ti5WO22 ceramics to room temperature, resulting in superior tunable properties. Specifically, the 0.7Bi6Ti5WO22-0.3Bi6Ti4Nb2O22 ceramics exhibit giant tunability (~75.6%) with ultralow loss (<0.002) under a low electric field (1.5 kV/mm). This tunability is twice that of barium strontium titanate ceramics with a similar dielectric constant and only one-tenth of the loss. Neutron powder diffraction and transmission-electron-microscopy illustrate the nanodomains and micro-strains influenced by ion substitution. Density functional theory simulation calculations reveal the contribution of ion substitution to polarization. The research provides an ideal substitute for tunable material and a general strategy for adjusting phase transition temperature to improve dielectric properties.

A systematic review and meta-analysis of magnetic resonance and computed tomography enterography in the diagnosis of small intestinal tumors.

Objective: To explore the potential value of magnetic resonance (MR) and computed tomography (CT) enterography in the diagnosis of small intestinal tumor (SIT). Methods: Articles reporting on the diagnosis of SIT by MR and CT enterography deposited in Chinese and foreign literature databases were identified and evaluated using the quality assessment of diagnostic accuracy studies (QUADAS). The diagnostic data extracted from the articles were adopted for meta-analysis using Meta-disc 1.40 software. Analysis was undertaken to compare the sensitivity, specificity, positive and negative likelihood ratios, and the diagnostic odds ratio (DOR) of MR and CT enterography in the diagnosis of SIT. The diagnostic values of the two imaging methods were analyzed by summary receiver operating characteristic (SROC) curves. The meta-analysis was registered at INPLASY (202380053). Results: A total of eight articles, including 551 cases of SIT were included in this analysis. The pooled sensitivity and specificity of MR enterography were 0.92 (95% CI [0.89-0.95]) and 0.81 (95% CI [0.74-0.86]), respectively, whilst CT enterography had a sensitivity of 0.93 (95% CI [0.90-0.95]) and a specificity of 0.83 (95% CI [0.76-0.88]). For MR enterography, the combined positive likelihood ratio was 4.90 (95% CI [3.50-6.70]), the combined negative likelihood ratio was 0.10 (95% CI [0.07-0.14]), and the area under the receiver operating characteristic curve (AUROC) was 0.940. For CT enterography, the corresponding values were 5.40 (95% CI [3.90-7.40]), 0.08 (95% CI [0.06-0.12]), and 0.950, respectively. When the pretest probability for MR was assumed to be 50%, the posterior probabilities for positive and negative results were calculated as 83% and 9%, respectively. For CT enterography with a pretest probability of 50%, the posterior probabilities of positive and negative results were 84% and 8%, respectively. Conclusion: MR and CT enterography have high accuracy in the diagnosis of SIT and have a valuable role in the diagnosis and management of these tumors.

Preparation of boron nitride nanosheets by glucose-assisted ultrasonic cavitation exfoliation.

Boron nitride nanosheets (BNNSs) have been widely used in many fields due to their excellent properties. However, low preparation rates and difficulty in functionalization hinder their further development. This study proposes a novel glucose-assisted ultrasonic cavitation exfoliation (GAUCE) method with glucose as an auxiliary solution to prepare BNNSs. Results show that the method has a high preparation yield of 55.58%, which is higher than the average preparation yield of 33.86%. The mechanism of preparing BNNSs by GAUCE was also investigated. The exfoliation of BNNSs was achieved using the energy of ultrasonic cavitation bubble collapse, which will break the interlayer forces in h-BN. The grafting of hydroxyl groups decomposed by glucose on the edge and surface of BNNSs during cavitation prevented the re-aggregation of the nanosheets, thereby increasing the exfoliation yield of BNNSs. In addition, the contact angle of BNNSs prepared by GAUCE was reduced, and the hydrophilicity was greatly improved.

Design and Fabrication of a C-Band Dielectric Resonator Antenna with Novel Temperature-Stable Ce(Nb1-xVx)NbO4 (x = 0-0.4) Microwave Ceramics.

Vanadium(V)-substituted cerium niobate [Ce(Nb1-xVx)O4, CNVx] ceramics were prepared to explore their structure-microwave (MW) property relations and application in C-band dielectric resonator antennas (DRAs). X-ray diffraction and Raman spectroscopy revealed that CNVx (0.0 ≤ x ≤ 0.4) ceramics exhibited a ferroelastic phase transition at a critical content of V (xc = 0.3) from a monoclinic fergusonite structure to a tetragonal scheelite structure (TF-S), which decreased in temperature as a function of x according to thermal expansion analysis. Optimum microwave dielectric performance was obtained for CNV0.3 with permittivity (εr) of ∼16.81, microwave quality factor (Qf) of ∼41 300 GHz (at ∼8.7 GHz), and temperature coefficient of the resonant frequency (TCF) of ∼ -3.5 ppm/°C. εr is dominated by Ce-O phonon absorption in the microwave band; Qf is mainly determined by the porosity, grain size, and proximity of TF-S; and TCF is controlled by the structural distortions associated with TF-S. Terahertz (THz) (0.20-2.00 THz, εr ∼ 12.52 ± 0.70, and tan δ ∼ 0.39 ± 0.17) and infrared measurements are consistent, demonstrating that CNVx (0.0 ≤ x ≤ 0.4) ceramics are effective in the sub-millimeter as well as MW regime. A cylindrical DRA prototype antenna fabricated from CNV0.3 resonated at 7.02 GHz (|S11| = -28.8 dB), matching simulations, with >90% radiation efficiency and 3.34-5.93 dB gain.

Electrochemically-promoted synthesis of benzo[b]thiophene-1,1-dioxides via strained quaternary spirocyclization.

We report an approach for the synthesis of benzothiophene motifs under electrochemical conditions by the reaction of sulfonhydrazides with internal alkynes. Upon the formation of a quaternary spirocyclization intermediate by the selective ipso-addition instead of an ortho-attack, the S-migration process was rationalized to lead to the products. Computational studies revealed the selectivity and the compatibility of drug molecules showcased the potential application of the protocols.

Electrochemically Promoted [3 + 2] Annulation of Imidazo[1,2-a]pyridine with Alkynes.

The efficient electrochemically promoted [3 + 2] annulation of imidazo[1,2-a]pyridines with alkynes using traceless electrons as green reagents has been developed, leading to the synthesis of a large class of polycyclic heteroaromatics in good yields with a broad substrate scope under mild and green conditions. The scaled-up experiment, follow-up procedures, and potential biological applications show the practicability and feasibility of the electrochemical method.

The Wear Performance of Cu-Based Composites Reinforced with Boron Nitride Nanosheets.

Copper matrix composites (CMCs) were prepared by blending Cu particles with boron nitride nanosheets (BNNSs) and then by consolidating the blended particles using spark plasma sintering (SPS). The relative density of the compacts was over 99%, and an intact interface was formed between Cu and the BNNSs. Within the range of the BNNS content studied, its introduction improved microhardness and wear resistance. With the introduction of 0.2 vol% BNNSs, the friction coefficient reduced from 0.15 to merely 0.07, and the wear resistance improved by over 100%. This makes the CMCs reinforced with BNNSs promising materials in applications such as bearings.

Metabolite changes in prefrontal lobes and the anterior cingulate cortex correlate with processing speed and executive function in Parkinson disease patients.

Background: Processing speed and executive function can be impaired in patients with Parkinson disease (PD). However, the neural factors related to the slowdown in processing speed and dysexecutive function in PD are not completely understood. The objective of this study is to investigate the metabolic changes of the frontal and anterior cingulate cortex (ACC) through the use of 1H magnetic resonance spectroscopy and to explore the association between cognitive function and metabolic ratios. Methods: In this retrospective case-control study, we conducted neuropsychological assessments of executive function and information processing speed in healthy controls (HCs) and in patients with PD. Chemical information was obtained for the of N-acetyl-aspartate (NAA):creatine (Cr) ratio and the choline-containing compounds (Cho):Cr ratio within the bilateral prefrontal cortex and ACC. Using hierarchical multiple regression analysis, we analyzed the relationship between cognitive function and metabolic ratios in the bilateral prefrontal lobe and ACC in patients with PD. Results: In all, 59 patients with PD and 30 HCs were recruited. Patients with PD showed worse performance in executive function and processing speed compared with HCs (P<0.001). In patients with PD, the Cho:Cr ratios in the ACC (Z=2.20, P=0.028) and the right prefrontal cortex (t=2.16, P=0.034) were significantly increased. The hierarchical multiple regressions in patients with PD showed that the NAA:Cr ratio in the ACC correlated with the Stroop A completion times (P<0.05) and that the NAA:Cr ratio of the right prefrontal cortex correlated with the scores of the Wechsler Adult Intelligence Scale (WAIS)-Digit symbol test (P<0.05). Conclusions: Information processing speed and executive function are impaired in patients with PD. Neuronal integrity and membrane turnover in the ACC and the right prefrontal cortex may be important factors in the slowdown of the information processing speed in patients with PD.

The relationship between the accuracy of curling athletes' duration judgment and delivery performance.

Objective: Time perception is a critical point for curling athletes to have in order to successfully complete interactions between themselves and their environment. Exploring the relationship between the accuracy of duration judgment and curling athletes' performance is helpful to reveal the influencing factors on their performance and to provide a reference for the training of athletes' delivery performance. Methods: Thirty curling athletes and 30 non-athletes were recruited as participants. Using 3D modeling technology, curling videos of different situations were presented to the participants as stimulus information, and the participants were required to complete the duration judgment task. The neural activation of the participants during the entire process of duration judgment was recorded using electroencephalogram (EEG) equipment. The performance of the 30 curlers participating in the experiment was measured. Variance analyses were conducted on the collected behavioral and EEG data, and correlation and regression analyseswere conducted between behavioral data and delivery performance. Results: The accuracy of the distance judgment of curlers was higher than that of non-curlers (P < 0.05). In the stimulus video presentation stage, the power in the alpha band of curlers was higher than that of non-athletes (P < 0.05). In the task decision stage, the power in the alpha band of curlers was higher than that of non-athletes (P < 0.05), and the power in the theta band was higher than that of non-athletes (P < 0.05). There was a correlation between the accuracy of the curlers' perception of specific situational time intervals and the accuracy of delivery (P < 0.05). Regression analysis results were y = 3.422 + 1.415x. Conclusion: The accuracy of curling athletes' duration judgment is high in a specific situation. There is a correlation between the accuracy of duration judgment and delivery performance in a specific situation: the higher the accuracy of specific duration perception, the higher the performance accuracy of delivery. The cognitive strategies adopted by curlers differ from those adopted by non-athletes in the completion of duration judgment. Specifically, in a specific situation, fewer attention resources are utilized in the stimulus presentation and decision-making stages, while more memory resources are utilized in the decision-making stage to ensure higher accuracy of interval judgment. This study provides a new idea for exploring the causes of curling athletes' excellent technical performance and provides a reference for future curling research on competition training practice. Given the limitations of mobile EEG devices in this study, future studies can measure neural activity during actual delivery preparation and execution in an environment of high ecological validity to obtain more direct evidence.

Retinal microvascular impairment in Parkinson's disease with cognitive dysfunction.

BACKGROUND: Parkinson's disease (PD) is associated with structural alterations of the retina. However, it remains unknown whether these changes are present in PD with mild cognitive impairment (MCI). The purpose of the study was to evaluate the retinal microvasculature using optical coherence tomography angiography (OCTA) to assess possible retinal microvascular impairments associated with PD and PD with MCI. METHODS: This study included 83 eyes of 45 PD patients and 83 eyes of 42 healthy controls. All subjects underwent complete neurological and ophthalmological examinations before measurements. Cognitive function was also measured in PD patients. Retinal microvasculature was evaluated with OCTA. Vessel density in the superficial capillary plexus (SRCP), deep capillary plexus (DRCP), and radial peripapillary capillaries (RPC) and intraretinal layer thickness in the peripapillary retinal nerve fibre layer (RNFL) and ganglion cell complex (GCC) were analysed. Correlations between vessel density and cognitive function were analysed in the PD group. RESULTS: Parafoveal vessel density in the SRCP and DRCP were lower in the eyes of PD patients than healthy controls (P < 0.05). However, there were no significant differences in the RPC (P = 0.120), RNFL (P = 0.303) or GCC (P = 0.375) between PD patients and healthy controls. Lower executive function scores were associated with lower vessel density in the DRCP of PD patients (P < 0.05, 95% CI [0.133,1.342]). CONCLUSION: OCTA revealed lower macular microvascular density in PD patients and microvascular impairments in the deep retinal capillary layer in PD patients with executive dysfunction. These parameters might have potential utility as early disease diagnostic biomarkers.

Research on Comprehensive Evaluation Model of Physical Education Teaching Quality Based on Multivariate Data

Because of the complexity of the factors affecting the quality of teaching has obvious, lead to the larger error in the results of the assessment. Therefore, put forward the physical education teaching quality comprehensive evaluation model based on multivariate data research. Using the analytic hierarchy process (AHP) to build the physical teaching quality evaluation mechanism, based on the relative importance of data, establish compound consistency check of judgment matrix. The weights were assigned according to the importance of the data, and the weighted results were equally divided by the method of pulling apart grades. Finally, the physical education teaching quality was evaluated based on AHP-ISD model. The experimental results show that the accuracy of the method can reach more than 97%, which is obviously better than the method of comparison(AU)

Abnormal Neural Activity in Different Frequency Bands in Parkinson's Disease With Mild Cognitive Impairment.

Background: Abnormal spontaneous neural activity is often found in patients with Parkinson's disease with mild cognitive impairment (PD-MCI). However, the frequency dependence of neuronal interaction activities, especially the fractional amplitude of low-frequency fluctuation (fALFF) and degree centrality (DC), in PD-MCI is still unclear. Thus, this study aimed to explore the frequency dependence of PD-MCI based on fALFF and DC maps. Methods: Twenty-four patients with PD-MCI, 42 PD patients with normal cognition (PD-NC), and 33 healthy controls (HCs) were enrolled. Neuropsychological assessments and resting-state functional MRI (rs-fMRI) were performed. The fALFF and DC values in the conventional, slow4 and slow5 frequency bands were compared among the groups. Results: In the conventional frequency band, the DC value in the left precentral area was decreased in PD-MCI patients, while that in the right fusiform area was increased in PD-NC patients compared with HCs. Regarding fALFFs, both the PD-MCI and PD-NC patients had decreased values in the right precentral area compared with those of the HCs. The fALFFs did not differ between PD-MCI and PD-NC patients. The fALFF results in the slow4 subfrequency band were consistent with those in the conventional frequency band. In the slow5 band, the DC value in the left middle temporal lobe was higher in PD-MCI patients than in PD-NC patients and was positively correlated with the performance of the PD-MCI patients on the Montreal Cognitive Assessment (MoCA). Additionally, both PD-MCI and PD-NC patients showed lower fALFF values in the bilateral putamen than the HCs, and the fALFF in the bilateral putamen was negatively correlated with the Hoehn and Yahr stages of PD-MCI. The fALFF in the left putamen was negatively correlated with the scores of PD-MCI patients on the Movement Disorder Society-Unified Parkinson Disease Rating Scale Part III (MDS-UPRDS-III). Conclusion: Our results suggested that abnormal neuronal activities, such as fALFF and DC, are dependent on frequency in PD-MCI. Some subfrequency bands could distinguish PD-MCI from PD. Our findings may be helpful for further revealing the frequency-dependent resting functional disruption in PD-MCI.

Reducing Defects Density and Enhancing Hole Extraction for Efficient Perovskite Solar Cells Enabled by π-Pb2+ Interactions.

Molecular doping is an of significance approach to reduce defects density of perovskite and to improve interfacial charge extraction in perovskite solar cells. Here, we show a new strategy for chemical doping of perovskite via an organic small molecule, which features a fused tricyclic core, showing strong intermolecular π-Pb2+ interactions with under-coordinated Pb2+ in perovskite. This π-Pb2+ interactions could reduce defects density of the perovskite and suppress the nonradiative recombination, which was also confirmed by the density functional theory calculations. In addition, this doping via π-Pb2+ interactions could deepen the surface potential and downshift the work function of the doped perovskite film, facilitating the hole extraction to hole transport layer. As a result, the doped device showed high efficiency of 21.41 % with ignorable hysteresis. This strategy of fused tricyclic core-based doping provides a new perspective for the design of new organic materials to improve the device performance.

Incorporating silica-coated graphene in bioceramic nanocomposites to simultaneously enhance mechanical and biological performance.

The applications of a variety of bioactive ceramics such as hydroxyapatite (HA) in orthopedics are limited by their insufficient mechanical properties, especially poor fracture toughness. Thus, further extending the clinical applications of these materials warrants the enhancement of their mechanical properties. Although the reinforcement of ceramics by 2D nanomaterials has been well recognized, integrated structural, mechanical, and functional considerations have been neglected in the design and synthesis of such composite materials. Herein, we report the first use of silica-coated reduced graphene oxide (S-rGO) hybrid nanosheets to create bioceramic-based composites with simultaneously enhanced mechanical and biological properties. In the representative HA-based bioceramic systems prepared by spark plasma sintering, S-rGO incorporation was found to be more effective for increasing the Young's modulus, hardness, and fracture toughness than the incorporation of uncoated reduced GO (rGO). Furthermore, when assessed with osteoblast-like MG-63 cells, such novel materials led to faster cell proliferation and higher cell viability and alkaline phosphatase activity than are generally observed with pure HA; additionally, cells demonstrate stronger affinity to S-rGO/HA than to rGO/HA composites. The S-rGO/bioceramic composites are therefore promising for applications in orthopedic tissue engineering, and this research provides valuable insights into the fabrication of silica-coated hybrid nanosheet-reinforced ceramics.

Neurogenic differentiation of adipose derived stem cells on graphene-based mat.

Adipose derived stem cells (ADSCs) have been proved as an abundant and accessible cell source with the ability to differentiate into neuron-like cells. However, the low differentiation efficiency puts forward an important challenge to practical applications in clinic. Considering of the good biocompatibility of graphene-based materials and the potential interaction between graphene and cells mentioned in previous studies, herein, we investigated the effect of graphene oxide (GO) and reduced graphene oxide (rGO) mats on neurogenic differentiation of the ADSCs. We demonstrated the excellent capabilities of graphene-based mats, especially GO to support the neural differentiation of ADSCs. By comparing the observation under an optical microscope and fluorescence microscope, the conversion rate of neuron-like cells reached about 90%. We consider that GO mat is better for promoting the differentiation of ADSCs into neuron-like cells, which compared to rGO based platforms. Meanwhile, we made an analysis of the mechanism by which graphene induced the differentiation of ADSCs to neuron-like cells. The data obtained here highlight the effect of GO mat on neurogenic differentiation of ADSCs and implicate the potential of graphene-based materials in application of neural tissue engineering for the limited self-repair capability of nerve cells.