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1.
ACS Omega ; 9(15): 17354-17367, 2024 Apr 16.
Artículo en Inglés | MEDLINE | ID: mdl-38645314

RESUMEN

Fluorite and calcite have been attracting research attention for a long time. This paper reports on an investigation of the use of diethylene triamine pentamethylphosphonic acid (DTPMPA) as a chelating inhibitor. DTPMPA was used as a chelating inhibitor to study the flotation, separation, and adsorption behaviors of fluorite and calcite minerals. The microflotation experiment showed that the maximum separation of fluorite and calcite can be achieved with a DTPMPA dosage of 1.5 × 10-4 mol/L under weakly alkaline conditions (pH = 8). Zeta potential measurement, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy were used to confirm that DTPMPA was adsorbed on the surface of calcite, inhibiting NaOl adsorption. Additionally, density functional theory calculations showed that oxygen in the DTPMPA phosphate group formed the most stable bidentate binuclear adsorption configuration by chelating with calcium on the calcite surface. Through detection analysis and simulation calculations, the results showed that DTPMPA exhibited significantly weaker adsorption on fluorite compared to that on calcite, highlighting its selective inhibition ability on calcite.

2.
Heliyon ; 10(7): e29092, 2024 Apr 15.
Artículo en Inglés | MEDLINE | ID: mdl-38601529

RESUMEN

Optically pumped magnetometers can provide functionality for bio-magnetic field detection and mapping. This has attracted widespread attention from researchers in the biomedical science field. Magnetocardiography has been proven to be an effective method for examining heart disease. Notably, vector magnetocardiography obtains more spatial information than the conventional method by only taking a component that is perpendicular to the chest surface. In this work, a spin-exchange-relaxation-free (SERF) magnetometer with a compact size of 14 mm × 25 mm × 90 mm was developed. The device has a high sensitivity of 25 fT/ Hz. Meanwhile, in the multichannel working mode, synchronous sensor manipulation and data acquisition can be achieved through our control software without additional data acquisition boards. Since a typical SERF magnetometer only responds to dual-axis magnetic fields, two sensors are orthogonally arranged to form a vector detection channel. Our system consists of seven channels and allows 7 × 9 vector MCG mapping by scanning. High-quality heart vector signals are measured, and P peak, QRS peak, and T peak can be distinguished clearly. To better demonstrate the vectorial information, a vector scatter plot form is also provided. Through a basic bio-electric current model, it demonstrates that triaxial MCG measurements capture a richer spatial current information than traditional uniaxial MCG, offering substantial diagnostic potential for heart diseases and shedding more light on the inversion of cardiac issues.

3.
J Multidiscip Healthc ; 17: 1127-1135, 2024.
Artículo en Inglés | MEDLINE | ID: mdl-38500481

RESUMEN

Objective: To probe into the influence of Helicobacter pylori (Hp) infection on glucose metabolism, lipid metabolism, and inflammatory cytokines in patients with nonalcoholic fatty liver disease (MASLD). Methods: A total of 140 MASLD patients admitted to our Hospital between June 2020 and May 2021 were selected as the research objects. Based on the presence or absence of Hp infection, they were divided into the study group (73 cases with infection) and control group (67 cases without infection). Glucose metabolism indicators [fasting blood glucose (FBG), 2-hour postprandial glucose (2hPG), fasting insulin (FINS), glycated hemoglobin (HbAlc)], lipid metabolism indicators [total cholesterol (TC), triglycerides (TG), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C)], and inflammatory indicators [interleukin-37 (IL-37), interleukin-18 (IL-18)] were measured and compared between the two groups. Results: In terms of glucose metabolism indicators, the study group exhibited higher levels of FBG (5.84±0.49 vs 5.40±0.51, t=2.535, P=0.012), 2hPG (7.26±1.30 vs 6.50±1.53, t=3.321, P<0.001), and FINS (11.13±4.13 vs 9.12±3.72, t=3.224, P<0.001), and Insulin resistance index (HOMA-IR) (2.97±0.35 VS 2.13±0.54, t=3.761, P<0.001) and a lower level of HbAlc (5.25±0.56 vs 6.12±0.57, t=5.473, P<0.001) compared to the control group. Regarding lipid metabolism indicators, the study group exhibited higher levels of TC (5.64±1.49 vs 5.01±1.32, t=3.332, P<0.001), TG (1.89±0.34 vs 1.32±0.43, t=3.411, P<0.001), and LDL-C (3.31±0.43 vs 2.12±0.29, t=4.142, P<0.001), and a lower level of HDL-C (1.45±0.21 vs 1.78±0.42, t=4.347, P<0.001) compared to the control group. As for the inflammatory indicators, the study group exhibited higher levels of IL-37 (45.56±6.02 vs 34.02±3.28, t=9.332, P<0.001) and IL-18 (73.57±5.82 vs 60.34±4.84, t=10.141, P<0.001) compared to the control group. Conclusion: It is crucial to place appropriate emphasis on the impact of Hp infection on the glucose metabolism, lipid metabolism, and inflammatory response in MASLD patients, warranting careful consideration during the treatment of these patients.

4.
Nat Commun ; 15(1): 2560, 2024 Mar 22.
Artículo en Inglés | MEDLINE | ID: mdl-38519493

RESUMEN

The development of high-performance lead-free K0.5Na0.5NbO3-based piezoceramics for replacing commercial lead-containing counterparts is crucial for achieving environmentally sustainable society. Although the proposed new phase boundaries (NPB) can effectively improve the piezoelectricity of KNN-based ceramics, the difficulty of achieving saturated poling and the underlying multiscale structures resolution of their complex microstructures are urgent issues. Here, we employ a medium entropy strategy to design NPB and utilize texture engineering to induce crystal orientation. The developed K0.5Na0.5NbO3-based ceramics enjoys both prominent piezoelectric performance and satisfactory Curie temperature, thus exhibiting an ultrahigh energy harvesting performance as well as excellent transducer performance, which is highly competitive in both lead-free and lead-based piezoceramics. Comprehensive structural analysis have ascertained that the field-induced efficient multiscale polarization configurations irreversible transitions greatly encourages high saturated poling. This study demonstrates a strategy for designing high-performance piezoceramics and establishes a close correlation between the piezoelectricty and the underlying multiscale structures.

5.
J Hazard Mater ; 469: 133910, 2024 May 05.
Artículo en Inglés | MEDLINE | ID: mdl-38432095

RESUMEN

Neonicotinoids (NEOs) have indeed become the most widely used insecticides worldwide. Concerns have been raised about their potential impact on newborns due to maternal exposure and their unique neurotoxic mode of action. However, it is still poorly understood whether in utero exposure of pregnant women to environmental NEOs and their metabolites can cause carryover effects on vulnerable newborns and subsequent health consequences. In this study, we determined the concentrations of 13 NEOs and their metabolites in the first urine collected from 92 newborns, both preterm and full-term, in southern China during 2020 and 2021. NEOs and their metabolites were identified in 91 urine samples, with over 93% of samples containing a cocktail of these compounds, confirming their maternal-fetal transfer. N-desmethyl-acetamiprid, imidaclothiz, clothianidin and flonicamid were the most commonly detected analytes, with detection frequencies of 59-87% and medians of 0.024-0.291 ng/mL in the urine. The relative abundance of imidaclothiz was significantly higher in preterm newborns, those with head circumferences below 33 cm, birth lengths less than 47 cm, and weights below 2500 g (p < 0.05). When comparing newborns in the 2nd quartile of imidaclothiz concentrations with those in the 1st quartile, we observed a significant increase in the odds of preterm outcomes in the unadjusted model (odds ratio = 3.24, 95% confidence interval = 1.02-10.3). These results suggest that exposure to elevated concentrations of imidaclothiz may be associated with preterm birth.


Asunto(s)
Insecticidas , Nacimiento Prematuro , Tiazoles , Humanos , Recién Nacido , Femenino , Embarazo , Insecticidas/análisis , Neonicotinoides , China , Nitrocompuestos
6.
Chem Commun (Camb) ; 60(19): 2633-2636, 2024 Feb 29.
Artículo en Inglés | MEDLINE | ID: mdl-38345643

RESUMEN

We explore an uncommon ultrasonic reduction method to exsolute Ag from perovskite La0.87Ag0.03FeO3-δ, forming a composite with enhanced catalytic oxidation activity. Such a mild exsolution is based on the coupling effect of ultrasonic cavitation and reducible BH4-, and holds great potential in the fields of energy and environment catalysis.

7.
Science ; 382(6673): 921-928, 2023 Nov 24.
Artículo en Inglés | MEDLINE | ID: mdl-37995213

RESUMEN

Thermoelectric interface materials (TEiMs) are essential to the development of thermoelectric generators. Common TEiMs use pure metals or binary alloys but have performance stability issues. Conventional selection of TEiMs generally relies on trial-and-error experimentation. We developed a TEiM screening strategy that is based on phase diagram predictions by density functional theory calculations. By combining the phase diagram with electrical resistivity and melting points of potential reaction products, we discovered that the semimetal MgCuSb is a reliable TEiM for high-performance MgAgSb. The MgCuSb/MgAgSb junction exhibits low interfacial contact resistivity (ρc <1 microhm square centimeter) even after annealing at 553 kelvin for 16 days. The fabricated two-pair MgAgSb/Mg3.2Bi1.5Sb0.5 module demonstrated a high conversion efficiency of 9.25% under a 300 kelvin temperature gradient. We performed an international round-robin testing of module performance to confirm the measurement reliability. The strategy can be applied to other thermoelectric materials, filling a vital gap in the development of thermoelectric modules.

8.
Therap Adv Gastroenterol ; 16: 17562848231207200, 2023.
Artículo en Inglés | MEDLINE | ID: mdl-37928895

RESUMEN

Background: Nivolumab plus chemotherapy (NC) was recently approved as the first-line intervention for human epidermal growth factor receptor 2-negative advanced gastric/gastroesophageal junction cancer (GC/GEJC). Moreover, in the latest KEYNOTE-859 (NCT03675737), pembrolizumab plus chemotherapy (PC) was demonstrated to produce remarkable patient survival outcomes. Objectives: The clinicians and patients need to assess NC and PC preference for cancer drugs. Design: The cost-effective analysis. Methods: In an economic assessment of the United States, United Kingdom, and Chinese healthcare systems using a Markov model simulated patients with GC/GEJC, two treatment decision branches with three health states and a tracked time horizon of 15 years were developed. The overall cost and efficacy outcomes of first-line strategies PC and NC were evaluated at willingness-to-pay (WTP) thresholds of different national, including life-years (LYs), quality-adjusted life-years (QALYs), incremental cost-effectiveness ratios (ICERs), and incremental net-health benefit (INHB). Sensitivity and subgroup analyses were considered. Results: Given a WTP threshold of $150,000, $60,161, and $37,653 per QALY in the United States, United Kingdom, and China, respectively, both PC and NC achieved QALYs of 1.67 and 1.65 (2.51 and 2.48 LYs), 1.65 and 1.63 (2.48 and 2.45 LYs), and 1.60 and 1.58 (2.40 and 2.37 LYs), with total costs of $242,444 and $232,617, $148,367 and $127,737, and $16,693 and $24,016, respectively. Based on our sensitivity analysis, the programmed death-1 inhibitors cost produced the largest impact on the outcome. In addition, the cost-effectiveness probabilities of PC were 38.3%, 4.1%, and 100% in the three aforementioned countries, respectively. Conclusion: In the case of the Chinese payers' perspective, PC appeared more dominant as first-line therapy for advanced GC/GEJC patients, whereas NC was preferred in the United States and United Kingdom.

9.
Front Oncol ; 13: 1168995, 2023.
Artículo en Inglés | MEDLINE | ID: mdl-37954080

RESUMEN

Purpose: This study aims to develop and validate a model predictive for the incidence of grade 4 radiation-induced lymphopenia (G4RIL), based on dosiomics features and radiomics features from the planning CT of nasopharyngeal carcinoma (NPC) treated by radiation therapy. Methods: The dataset of 125 NPC patients treated with radiotherapy from August 2018 to March 2019 was randomly divided into two sets-an 85-sample training set and a 40-sample test set. Dosiomics features and radiomics features of the CT image within the skull bone and cervical vertebrae were extracted. A feature selection process of multiple steps was employed to identify the features that most accurately forecast the data and eliminate superfluous or insignificant ones. A support vector machine learning classifier with correction for imbalanced data was trained on the patient dataset for prediction of RIL (positive classifier for G4RIL, negative otherwise). The model's predictive capability was gauged by gauging its sensitivity (the likelihood of a positive test being administered to patients with G4RIL) and specificity in the test set. The area beneath the ROC curve (AUC) was utilized to explore the association of characteristics with the occurrence of G4RIL. Results: Three clinical features, three dosiomics features, and three radiomics features exhibited significant correlations with G4RIL. Those features were then used for model construction. The combination model, based on nine robust features, yielded the most impressive results with an ACC value of 0.88 in the test set, while the dosiomics model, with three dosiomics features, had an ACC value of 0.82, the radiomics model, with three radiomics features, had an ACC value of 0.82, and the clinical model, with its initial features, had an ACC value of 0.6 for prediction performance. Conclusion: The findings show that radiomics and dosiomics features are correlated with the G4RIL of NPC patients. The model incorporating radiomics features and dosiomics features from planning CT can predict the incidence of G4RIL in NPC patients.

10.
Biomolecules ; 13(9)2023 09 18.
Artículo en Inglés | MEDLINE | ID: mdl-37759806

RESUMEN

SUPPRESSOR OF MAX2-LIKE 6, 7, and 8 (SMXL6,7,8) function as repressors and transcription factors of the strigolactone (SL) signaling pathway, playing an important role in the development and stress tolerance in Arabidopsis thaliana. However, the molecular mechanism by which SMXL6,7,8 negatively regulate drought tolerance and ABA response remains largely unexplored. In the present study, the interacting protein and downstream target genes of SMXL6,7,8 were investigated. Our results showed that the substrate receptor for the CUL4-based E3 ligase DDB1-BINDING WD-REPEAT DOMAIN (DWD) HYPERSENSITIVE TO ABA DEFICIENT 1 (ABA1) (DWA1) physically interacted with SMXL6,7,8. The degradation of SMXL6,7,8 proteins were partially dependent on DWA1. Disruption of SMXL6,7,8 resulted in increased drought tolerance and could restore the drought-sensitive phenotype of the dwa1 mutant. In addition, SMXL6,7,8 could directly bind to the promoter of SUCROSE NONFERMENTING 1 (SNF1)-RELATED PROTEIN KINASE 2.3 (SnRK2.3) to repress its transcription. The mutations in SnRK2.2/2.3 significantly suppressed the hypersensitivity of smxl6/7/8 to ABA-mediated inhibition of seed germination. Conclusively, SMXL6,7,8 interact with DWA1 to negatively regulate drought tolerance and target ABA-response genes. These data provide insights into drought tolerance and ABA response in Arabidopsis via the SMXL6,7,8-mediated SL signaling pathway.


Asunto(s)
Arabidopsis , Hipersensibilidad , Humanos , Resistencia a la Sequía , Arabidopsis/genética , Ácido Abscísico/farmacología , Repeticiones WD40 , Factores de Transcripción/genética , Sacarosa , Proteínas de Unión al ADN/genética
11.
Eur J Radiol ; 168: 111084, 2023 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-37722143

RESUMEN

OBJECTIVES: Accuracy in the detection of recurrent nasopharyngeal carcinoma (NPC) on follow-up magnetic resonance (MR) scans needs to be improved. MATERIAL AND METHODS: A total of 5 035 follow-up MR scans from 5 035 survivors with treated NPC between April 2007 and July 2020 were retrospectively collected from three cancer centers for developing and evaluating the deep learning (DL) model MODERN (MR-based Deep learning model for dEtecting Recurrent Nasopharyngeal carcinoma). In a reader study with 220 scans, the accuracy of two radiologists in detecting recurrence on scans with vs without MODERN was evaluated. The performance was measured using the area under the receiver operating characteristic curve (ROC-AUC) and accuracy with a 95% confidence interval (CI). RESULTS: MODERN exhibited sound performance in the validation cohort (internal: ROC-AUC, 0.88, 95% CI, 0.86-0.90; external 1: ROC-AUC, 0.88, 95% CI, 0.86-0.90; external 2: ROC-AUC, 0.85, 95% CI, 0.82-0.88). In a reader study, MODERN alone achieved reliable accuracy compared to that of radiologists (MODERN: 84.1%, 95% CI, 79.3%-88.9%; competent: 80.9%, 95% CI, 75.7%-86.1%, P < 0.001; expert: 85.9%, 95% CI, 81.3%-90.5%, P < 0.001). The accuracy of radiologists was boosted by the MODERN score (competent with MODERN score: 84.6%, 95% CI, 79.8%-89.3%, P < 0.001; expert with MODERN score: 87.7%, 95% CI, 83.4%-92.1%, P < 0.001). CONCLUSION: We developed a DL model for recurrence detection with reliable performance. Computer-human collaboration has the potential to refine the workflow in interpreting surveillant MR scans among patients with treated NPC.


Asunto(s)
Aprendizaje Profundo , Neoplasias Nasofaríngeas , Humanos , Carcinoma Nasofaríngeo/diagnóstico por imagen , Estudios Retrospectivos , Recurrencia Local de Neoplasia/diagnóstico por imagen , Imagen por Resonancia Magnética , Neoplasias Nasofaríngeas/diagnóstico por imagen , Neoplasias Nasofaríngeas/patología , Espectroscopía de Resonancia Magnética
12.
Plant Cell Rep ; 42(10): 1629-1649, 2023 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-37597006

RESUMEN

KEY MESSAGE: AtHSPR forms a complex with KNAT5 and OFP1 to regulate primary root growth through GA-mediated root meristem activity. KNAT5-OFP1 functions as a negative regulator of AtHSPR in response to GA. Plant root growth is modulated by gibberellic acid (GA) signaling and depends on root meristem maintenance. ARABIDOPSIS THALIANA HEAT SHOCK PROTEIN-RELATED (AtHSPR) is a vital regulator of flowering time and salt stress tolerance. However, little is known about the role of AtHSPR in the regulation of primary root growth. Here, we report that athspr mutant exhibits a shorter primary root compared to wild type and that AtHSPR interacts with KNOTTED1-LIKE HOMEOBOX GENE 5 (KNAT5) and OVATE FAMILY PROTEIN 1 (OFP1). Genetic analysis showed that overexpression of KNAT5 or OFP1 caused a defect in primary root growth similar to that of the athspr mutant, but knockout of KNAT5 or OFP1 rescued the short root phenotype in the athspr mutant by altering root meristem activity. Further investigation revealed that KNAT5 interacts with OFP1 and that AtHSPR weakens the inhibition of GIBBERELLIN 20-OXIDASE 1 (GA20ox1) expression by the KNAT5-OFP1 complex. Moreover, root meristem cell proliferation and root elongation in 35S::KNAT5athspr and 35S::OFP1athspr seedlings were hypersensitive to GA3 treatment compared to the athspr mutant. Together, our results demonstrate that the AtHSPR-KNAT5-OFP1 module regulates root growth and development by impacting the expression of GA biosynthetic gene GA20ox1, which could be a way for plants to achieve plasticity in response to the environment.


Asunto(s)
Proteínas de Arabidopsis , Arabidopsis , Arabidopsis/genética , Giberelinas/farmacología , Proliferación Celular , Proteínas de Choque Térmico , Meristema/genética , Factores de Transcripción/genética , Proteínas de Homeodominio , Proteínas de Arabidopsis/genética
13.
IEEE J Biomed Health Inform ; 27(12): 6088-6099, 2023 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-37384472

RESUMEN

Radiation therapy is the primary treatment for recurrent nasopharyngeal carcinoma. However, it may induce necrosis of the nasopharynx, leading to severe complications such as bleeding and headache. Therefore, forecasting necrosis of the nasopharynx and initiating timely clinical intervention has important implications for reducing complications caused by re-irradiation. This research informs clinical decision-making by making predictions on re-irradiation of recurrent nasopharyngeal carcinoma using deep learning multi-modal information fusion between multi-sequence nuclear magnetic resonance imaging and plan dose. Specifically, we assume that the hidden variables of model data can be divided into two categories: task-consistency and task-inconsistency. The task-consistency variables are characteristic variables contributing to target tasks, while the task-inconsistency variables are not apparently helpful. These modal characteristics are adaptively fused when the relevant tasks are expressed through the construction of supervised classification loss and self-supervised reconstruction loss. The cooperation of supervised classification loss and self-supervised reconstruction loss simultaneously reserves the information of characteristic space and controls potential interference simultaneously. Finally, multi-modal fusion effectively fuses information through an adaptive linking module. We evaluated this method on a multi-center dataset. and found the prediction based on multi-modal features fusion outperformed predictions based on single-modal, partial modal fusion or traditional machine learning methods.


Asunto(s)
Aprendizaje Profundo , Neoplasias Nasofaríngeas , Reirradiación , Humanos , Carcinoma Nasofaríngeo/diagnóstico por imagen , Carcinoma Nasofaríngeo/radioterapia , Pronóstico , Necrosis , Neoplasias Nasofaríngeas/diagnóstico por imagen , Neoplasias Nasofaríngeas/radioterapia
14.
J Bioinform Comput Biol ; 21(3): 2350012, 2023 06.
Artículo en Inglés | MEDLINE | ID: mdl-37325865

RESUMEN

Based on the colorectal cancer microarray sets gene expression data series (GSE) GSE10972 and GSE74602 in colon cancer and 222 autophagy-related genes, the differential signature in colorectal cancer and paracancerous tissues was analyzed by RankComp algorithm, and a signature consisting of seven autophagy-related reversal gene pairs with stable relative expression orderings (REOs) was obtained. Scoring based on these gene pairs could significantly distinguish colorectal cancer samples from adjacent noncancerous samples, with an average accuracy of 97.5% in two training sets and 90.25% in four independent validation GSE21510, GSE37182, GSE33126, and GSE18105. Scoring based on these gene pairs also accurately identifies 99.85% of colorectal cancer samples in seven other independent datasets containing a total of 1406 colorectal cancer samples.


Asunto(s)
Neoplasias del Colon , Neoplasias Colorrectales , Humanos , Perfilación de la Expresión Génica , Neoplasias del Colon/genética , Algoritmos , Neoplasias Colorrectales/diagnóstico , Neoplasias Colorrectales/genética , Regulación Neoplásica de la Expresión Génica
16.
Bioengineering (Basel) ; 10(4)2023 Mar 30.
Artículo en Inglés | MEDLINE | ID: mdl-37106623

RESUMEN

Based on the principles of neuromechanics, human arm movements result from the dynamic interaction between the nervous, muscular, and skeletal systems. To develop an effective neural feedback controller for neuro-rehabilitation training, it is important to consider both the effects of muscles and skeletons. In this study, we designed a neuromechanics-based neural feedback controller for arm reaching movements. To achieve this, we first constructed a musculoskeletal arm model based on the actual biomechanical structure of the human arm. Subsequently, a hybrid neural feedback controller was developed that mimics the multifunctional areas of the human arm. The performance of this controller was then validated through numerical simulation experiments. The simulation results demonstrated a bell-shaped movement trajectory, consistent with the natural motion of human arm movements. Furthermore, the experiment testing the tracking ability of the controller revealed real-time errors within one millimeter, with the tensile force generated by the controller's muscles being stable and maintained at a low value, thereby avoiding the issue of muscle strain that can occur due to excessive excitation during the neurorehabilitation process.

17.
Phys Rev Lett ; 130(15): 153803, 2023 Apr 14.
Artículo en Inglés | MEDLINE | ID: mdl-37115865

RESUMEN

Orbital angular momentum (OAM) conservation plays an important role in shaping and controlling structured light with nonlinear optics. The OAM of a beam originating from three-wave mixing should be the sum or difference of the other two inputs because no light-matter OAM exchange occurs in parametric nonlinear interactions. Here, we report anomalous OAM transfer in parametric upconversion, in which a Hermite-Gauss mode signal interacts with a specially engineered pump capable of astigmatic transformation, resulting in Laguerre-Gaussian mode sum-frequency generation (SFG). The anomaly here refers to the fact that the pump and signal both carry no net OAM, while their SFG does. We reveal experimentally that there is also an OAM inflow to the residual pump, having the same amount of that to the SFG but with the opposite sign, and thus holds system OAM conservation. This unexpected OAM selection rule improves our understanding of OAM transfer among interacting waves and may inspire new ideas for controlling OAM states via nonlinear optics.

18.
Inorg Chem ; 62(19): 7273-7282, 2023 May 15.
Artículo en Inglés | MEDLINE | ID: mdl-37116190

RESUMEN

Highly efficient and eco-friendly thermoelectric generators rely on low-cost and nontoxic semiconductors with high symmetry and ultralow lattice thermal conductivity κL. We report the rational synthesis of the novel cubic (Ag, Se)-doped Cu2GeTe3 semiconductors. A localized symmetry breakdown (LSB) was found in the composition of Cu1.9Ag0.1GeTe1.5Se1.5 (i.e., CAGTS15) with an ultralow κL of 0.37 W/mK at 723 K, the lowest value outperforming all Cu2GeCh3 (Ch = S, Se, and Te). A joint investigation of synchrotron X-ray techniques identifies the LSB embedded into the cubic CAGTS15 host matrix. This LSB is an Ångström-scale orthorhombic symmetry unit, characteristic of multiple bond lengths, large anisotropic atomic displacements, and distinct local chemical coordination of anions. Computational results highlight that such an unusual orthorhombic symmetry demonstrates low-frequency phonon modes, which become softer and more predominant with increasing temperatures. This unconventional LSB promotes bond complexity and phonon scattering, highly beneficial for extraordinarily low lattice thermal conductivity.

19.
Science ; 380(6640): 87-93, 2023 Apr 07.
Artículo en Inglés | MEDLINE | ID: mdl-37023196

RESUMEN

The piezoelectric properties of lead zirconate titanate [Pb(Zr,Ti)O3 or PZT] ceramics could be enhanced by fabricating textured ceramics that would align the crystal grains along specific orientations. We present a seed-passivated texturing process to fabricate textured PZT ceramics by using newly developed Ba(Zr,Ti)O3 microplatelet templates. This process not only ensures the template-induced grain growth in titanium-rich PZT layers but also facilitates desired composition through interlayer diffusion of zirconium and titanium. We successfully prepared textured PZT ceramics with outstanding properties, including Curie temperatures of 360°C, piezoelectric coefficients d33 of 760 picocoulombs per newton and g33 of 100 millivolt meters per newton, and electromechanical couplings k33 of 0.85. This study addresses the challenge of fabricating textured rhombohedral PZT ceramics by suppressing the otherwise severe chemical reaction between PZT powder and titanate templates.

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