Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 84
Filtrar
Más filtros










Base de datos
Intervalo de año de publicación
1.
Lipids Health Dis ; 23(1): 159, 2024 May 27.
Artículo en Inglés | MEDLINE | ID: mdl-38802799

RESUMEN

BACKGROUND: Relative handgrip strength (RHGS) was positively correlated with healthy levels of cardiovascular markers and negatively correlated with metabolic disease risk. However, its association with hyperlipidemia remains unknown. The present study investigated the link between RHGS and hyperlipidemia, utilizing data from the National Health and Nutrition Examination Survey (NHANES) and further examined the hypothesis that inflammation may serve a mediating role within this relationship. METHODS: Data were extracted from 4610 participants in the NHANES database spanning 2011-2014 to explore the correlation between RHGS and hyperlipidemia using multivariate logistic regression models. Subgroup analyses were conducted to discern the correlation between RHGS and hyperlipidemia across diverse populations. Additionally, smooth curve fitting and threshold effect analysis were conducted to validate the association between RHGS and hyperlipidemia. Furthermore, the potential mediating effect of inflammation on this association was also explored. RESULTS: According to the fully adjusted model, RHGS was negatively correlated with hyperlipidemia [odds ratio (OR) = 0.575, 95% confidence interval (CI) = 0.515 to 0.643], which was consistently significant across all populations, notably among women. Smooth curve fitting and threshold effect analysis substantiated the negative association between RHGS and hyperlipidemia. Moreover, the mediating effects analysis indicated the white blood cell (WBC) count, neutrophil (Neu) count, and lymphocyte (Lym) count played roles as the mediators, with mediation ratios of 7.0%, 4.3%, and 5.0%, respectively. CONCLUSIONS: This study identified a prominent negative correlation between RHGS and hyperlipidemia. Elevated RHGS may serve as a protective factor against hyperlipidemia, potentially through mechanisms underlying the modulation of inflammatory processes.


Asunto(s)
Fuerza de la Mano , Hiperlipidemias , Inflamación , Encuestas Nutricionales , Humanos , Hiperlipidemias/fisiopatología , Hiperlipidemias/sangre , Hiperlipidemias/epidemiología , Femenino , Masculino , Inflamación/sangre , Persona de Mediana Edad , Adulto , Recuento de Leucocitos , Anciano , Oportunidad Relativa , Modelos Logísticos , Neutrófilos
2.
Angew Chem Int Ed Engl ; 63(18): e202401331, 2024 Apr 24.
Artículo en Inglés | MEDLINE | ID: mdl-38456641

RESUMEN

A general approach to constructing room temperature phosphorescence (RTP) materials involves the incorporation of a phosphorescent emitter into a rigid host or polymers with high glass transition temperature. However, these materials often suffer from poor processability and suboptimal mechanical properties, limiting their practical applications. In this work, we developed benzothiadiazole-based dialkene (BTD-HEA), a multifunctional phosphorescent emitter with a remarkable yield of intersystem crossing (ΦISC, 99.83 %). Its high triplet exciton generation ability and dialkene structure enable BTD-HEA to act as a photoinitiator and crosslinker, efficiently initiating the polymerization of various monomers within 120 seconds. A range of flexible phosphorescence gels, including hydrogels, organogels, ionogels, and aerogels were fabricated, which exhibit outstanding stretchability and recoverability. Furthermore, the unique fluorescent-phosphorescent colorimetric properties of the gels provide a more sensitive method for the visual determination of the polymerization process. Notably, the phosphorescent emission intensity of the hydrogel can be increased by the formation of ice, allowing for the precise detection of hydrogel freezing. The versatility of this emitter paves the way for fabricating various flexible phosphorescence gels with diverse morphologies using microfluidics, film-shearing, roll coating process, and two/three-dimensional printing, showcasing its potential applications in the fields of bioimaging and bioengineering.

3.
Chem Asian J ; 19(9): e202400049, 2024 May 02.
Artículo en Inglés | MEDLINE | ID: mdl-38450996

RESUMEN

This paper explores recent advancements in the field of circularly polarized luminescence (CPL) exhibited by small and isolated organic molecules. The development and application of small CPL molecule are systematically reviewed through eight different chiral skeleton sections. Investigating the intricate interplay between molecular structure and CPL properties, the paper aims at providing and enlighting novel strategies for CPL-based applications.

4.
Front Oncol ; 14: 1354872, 2024.
Artículo en Inglés | MEDLINE | ID: mdl-38469243

RESUMEN

It is usually believed that differentiated thyroid cancer is less likely to have distant metastases and rarely occurs secondary to hyperthyroidism. In our case report, we describe a patient diagnosed with thyroid fetal adenoma in 2002 who subsequently presented with a painful lump in her right rib. Through puncture biopsy, the mass was considered as metastatic follicular thyroid carcinoma, and then she appeared to have hyperthyroidism. The results of SPECT examination and other tests suggested that the hyperthyroidism was secondary to the thyroid cancer. The patient further underwent total thyroidectomy, and the pathology did not find any follicular thyroid foci. In this article, we analyze and discuss this case and review the relevant literature.

5.
Micromachines (Basel) ; 15(2)2024 Jan 24.
Artículo en Inglés | MEDLINE | ID: mdl-38398901

RESUMEN

In this study, the electrical characteristics of depletion-mode AlGaN/GaN high-electron-mobility transistors (HEMTs) with a SiNx gate dielectric were tested under hydrogen exposure conditions. The experimental results are as follows: (1) After hydrogen treatment at room temperature, the threshold voltage VTH of the original device was positively shifted from -16.98 V to -11.53 V, and the positive bias of threshold was 5.45 V. When the VDS was swept from 0 to 1 V with VGS of 0 V, the IDS was reduced by 25% from 9.45 A to 7.08 A. (2) Another group of original devices with identical electrical performance, after the same duration of hydrogen treatment at 100 °C, exhibited a reverse shift in threshold voltage with a negative threshold shift of -0.91 V. The output characteristics were enhanced, and the saturation leakage current was increased. (3) The C-V method and the low-frequency noise method were used to investigate the effect of hydrogen effect on the device interface trap and border trap, respectively. It was found that high-temperature hydrogen conditions can passivate the interface/border traps of SiNx/AlGaN, reducing the density of interface/border traps and mitigating the trap capture effect. However, in the room-temperature hydrogen experiment, the concentration of interface/border traps increased. The research findings in this paper provide valuable references for the design and application of depletion-mode AlGaN/GaN HEMT devices.

6.
Nat Commun ; 15(1): 157, 2024 Jan 02.
Artículo en Inglés | MEDLINE | ID: mdl-38167854

RESUMEN

Controlling the formation of clathrate hydrates is crucial for advancing hydrate-based technologies. However, the microscopic mechanism underlying clathrate hydrate formation through nucleation remains poorly elucidated. Specifically, the critical nucleus, theorized as a pivotal step in nucleation, lacks empirical validation. Here, we report uniform nanoparticles, e.g., graphene oxide (GO) nanosheets and gold or silver nanocubes with controlled sizes, as nanoprobes to experimentally measure the size of the critical nucleus of tetrahydrofuran (THF) clathrate hydrate formation. The capability of the nanoparticles in facilitating THF clathrate hydrate nucleation displays generally an abrupt change at a nanoparticle-size-determined specific supercooling. It is revealed that the free-energy barrier shows an abrupt change when the nanoparticles have an approximately the same size as that of the critical nucleus. Thus, it is inferred that THF clathrate hydrate nucleation involves the creation of a critical nucleus with its size being inversely proportional to the supercooling. By proving the existence and determining the supercooling-dependent size of the critical nucleus of the THF clathrate hydrates, this work brings insights in the microscopic pictures of the clathrate hydrate nucleation.

7.
Small ; 20(2): e2305379, 2024 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-37658512

RESUMEN

The fabrication of perovskite light-emitting diodes (PeLEDs) with vacuum deposition shows great potential and commercial value in realizing large-area display panel manufacturing. However, the electroluminescence (EL) performance of vacuum-deposited PeLEDs still lags behind the counterparts fabricated by solution process, especially in the field of blue PeLEDs. Here, the fabrication of high-quality CsPbBr3- x Clx film through tri-source co-evaporation is reported to achieve high photoluminescence quantum yield (PLQY). Compared with the conventional traditional dual-source co-evaporation, the tri-source co-evaporation method allows for freely adjustable elemental ratios, enabling the introduction of the lattice-matched Cs4 Pb(Br/Cl)6 phase with the quantum-limited effect into the inorganic CsPb(Br/Cl)3 emitter. By adjusting the phase distribution, the surface defects of the emitter can be effectively reduced, leading to better blue emission and film quality. Further, the effects of Cs/Pb ratio and Br/Cl ratio on the PLQY and carrier recombination dynamics of perovskite films are investigated. By optimizing the deposition rate of each precursor source, spectrally stable blue PeLEDs are achieved with tunable emission ranging from 468 to 488 nm. Particularly, the PeLEDs with an EL peak at 488 nm show an external quantum efficiency (EQE) of 4.56%, which is the highest EQE value for mixed-halide PeLEDs fabricated by vacuum deposition.

8.
Front Immunol ; 14: 1291846, 2023.
Artículo en Inglés | MEDLINE | ID: mdl-38149240

RESUMEN

Short-chain fatty acids (SCFA) are a class of organic fatty acids that consist of 1 to 6 carbons in length. They are primary end-products which arise from non-digestible carbohydrates (NDC) fermentation of colonic bacteria. They are the fundamental energy sources for post-weaning ruminants. SCFA represent the major carbon flux of diet through the gut microbiota to the host. They also play a vital role in regulating cell expansion and gene expression of the gastrointestinal tract (GIT). Recently, remarkable progresses have been made in understanding the immunomodulatory effects of SCFA and their interactions with the host. The processes involved in this study encompassed inflammasome activation, proliferation of lymphocytes, and maturation of intestinal mucosal immunity maturation. It is important to note that the establishment and maturation of intestinal mucosal immune system are intricately connected to the barrier function of intestinal epithelial cells (IEC) and the homeostasis of gut microbiota. Thus, insights into the role of SCFA in enteric mucosal immunoreaction of calves will enhance our understanding of their various regulatory functions. This review aims to analyze recent evidence on the role of SCFA as essential signaling molecules between gut microbiota and animal health. Additionally, we provide a summary of current literature on SCFA in intestinal mucosal immune responses of dairy calves.


Asunto(s)
Ácidos Grasos Volátiles , Inmunidad Mucosa , Animales , Bovinos , Fermentación , Ácidos Grasos Volátiles/metabolismo , Carbohidratos , Bacterias/metabolismo
9.
Micromachines (Basel) ; 14(10)2023 Sep 30.
Artículo en Inglés | MEDLINE | ID: mdl-37893328

RESUMEN

In this research, a high-efficiency design method of the capacitive MEMS accelerometer is proposed. As the MEMS accelerometer has high precision and a compact structure, much research has been carried out, which mainly focused on the structural design and materials selection. To overcome the inconvenience and inaccuracy of the traditional design method, an orthogonal design and the particle swarm optimization (PSO) algorithm are introduced to improve the design efficiency. The whole process includes a finite element method (FEM) simulation, high-efficiency design, and verification. Through the theoretical analysis, the working mechanism of capacitive MEMS accelerometer is clear. Based on the comparison among the sweep calculation results of these parameters in the FEM software, four representative structural parameters are selected for further study, and they are le, nf, lf and wPM, respectively. le and lf are the length of the sensing electrode and fixed electrode on the right. nf is the number of electrode pairs, and wPM is the width of the mass block. Then, in order to reduce computation, an orthogonal design is adopted and finally, 81 experimental groups are produced. Sensitivity SV and mass Ma are defined as evaluation parameters, and structural parameters of experimental groups are imported into the FEM software to obtain the corresponding calculation results. These simulation data are imported into neural networks with the PSO algorithm. For a comprehensively accurate examination, three cases are used to verify our design method, and every case endows the performance parameters with different weights and expected values. The corresponding structural parameters of each case are given out after 24 iterations. Finally, the maximum calculation errors of SV and Ma are 1.2941% and 0.1335%, respectively, proving the feasibility of the high-efficiency design method.

10.
Materials (Basel) ; 16(18)2023 Sep 13.
Artículo en Inglés | MEDLINE | ID: mdl-37763469

RESUMEN

In this work, the influences of special environments (hydrogen gas and high temperature, high humidity environments) on the performance of three types of SiC MOSFETs are investigated. The results reveal several noteworthy observations. Firstly, after 500 h in a hydrogen gas environment, all the SiC MOSFETs exhibited a negative drift in threshold voltage, accompanied by an increase in maximum transconductance and drain current (@ VGS/VDS = 13 V/3 V). This phenomenon can be attributed to that the hydrogen atoms can increase the positive fixed charges in the oxide and increase the electron mobility in the channel. In addition, high temperature did not intensify the impact of hydrogen on the devices and electron mobility. Instead, prolonged exposure to high temperatures may induce stress on the SiO2/SiC interface, leading to a decrease in electron mobility, subsequently reducing the transconductance and drain current (@ VGS/VDS = 13 V/3 V). The high temperature, high humidity environment can cause a certain negative drift in the devices' threshold voltage. With the increasing duration of the experiment, the maximum transconductance and drain current (@ VGS/VDS = 18V (20 V)/3 V) gradually decreased. This may be because the presence of moisture can lead to corrosion of the devices' metal contacts and interconnects, which can increase the devices' resistance and lead to a decrease in the devices' maximum transconductance and drain current.

11.
Eur J Med Res ; 28(1): 259, 2023 Jul 27.
Artículo en Inglés | MEDLINE | ID: mdl-37501165

RESUMEN

OBJECTIVES: Previous studies have shown that there may be a positive correlation between serum uric acid levels and hyperthyroidism. However, the relationship between thyroid function and serum uric acid in healthy people is unclear. This study analyzed the relationship between impaired thyroid hormone sensitivity and serum uric acid levels, and presented them in quantitative form. RESEARCH DESIGN AND METHODS: This is a cross-sectional study of 4460 adults (male: 2300; female: 2160) who participated in the National Health and Nutrition Examination Survey (NHANES) from 2007 to 2010. Parameters representing central sensitivity to thyroid hormones were calculated as: thyroid feedback quantile-based index (TFQIFT4), thyroid stimulating hormone index (TSHI), and total thyroxine (T4) resistance index (TT4RI); Peripheral sensitivity to thyroid hormone was evaluated by FT3/FT4 ratio. In addition, we have innovated total triiodothyronine (T3) resistance index (TT3RI) and TFQIFT3 indexes based on FT3 and TSH. Multiple linear regression models were used to evaluate the correlation between thyroid resistance index and serum uric acid, and the results were presented graphically as smooth curve fittings. RESULTS: Higher levels of serum uric acid were associated with decreased sensitivity to thyroid hormones in euthyroid individuals. In conjunction with an increase in the thyroid hormone sensitivity index value, uric acid levels gradually increased as well. Furthermore, we found a segmented relationship between TT3RI and serum uric acid changes. The saturation and threshold analyses indicated that 18.85 was the turning point (logarithmic likelihood ratio test = 0.036). When TT3RI < 18.85, the relationship between serum uric acid and TT3RI was not significant [ß(95% CI) 0.47 (- 0.05, 1.00), P = 0.077], but when TT3RI > 18.85, there was a significant rise in serum uric acid with an increase in TT3RI [ß(95% CI) 3.94 (0.94, 6.95), P = 0.010]. A further finding of the interaction test was that impaired thyroid hormone sensitivity and uric acid changes vary among different age groups and BMI levels. CONCLUSIONS: Decreased sensitivity to thyroid hormones was associated with high levels of serum uric acid in people with normal thyroid function. The interaction test shows that different age groups and BMI groups impact the association between impaired thyroid hormone sensitivity and serum uric acid. Furthermore, smooth curve fitting revealed a segmental relationship between TT3RI and serum uric acid levels.


Asunto(s)
Glándula Tiroides , Ácido Úrico , Adulto , Masculino , Humanos , Femenino , Encuestas Nutricionales , Estudios Transversales , Retroalimentación , Hormonas Tiroideas
12.
Food Chem ; 427: 136648, 2023 Nov 30.
Artículo en Inglés | MEDLINE | ID: mdl-37399644

RESUMEN

It is necessary to efficient detection hydrazine in food. Exploring highly sensitive, low-cost and fast response electrochemical hydrazine sensing methods has been a challenge in this field. In this paper, a conformal transformation method is used to prepare rose flower-like NiCo-LDH derivating from the bimetallic NiCo-MOFs, and the N2H4 sensing platform with a large electrocatalytic area, high conductivity and good stability was constructed. Based on the synergy between Ni and Co and the remarkable catalytic activity of the rough 3D flower-like structure, the N2H4 sensor has a linear response in the concentration range of 0.001-1 mmol/L and 1-7 mmol/L, with a sensitivity of 5342 µA L mmol-1 cm-2 and 2965 µA L mmol-1 cm-2 (S/N = 3), respectively, and low limit of detection of 0.043 µmol/L. This study opens a new door for the successful application of electrochemical sensors to detect N2H4 in real food samples.


Asunto(s)
Técnicas Electroquímicas , Flores , Análisis por Conglomerados , Conductividad Eléctrica , Electrodos
13.
Oral Dis ; 2023 Apr 24.
Artículo en Inglés | MEDLINE | ID: mdl-37094078

RESUMEN

OBJECTIVE: We aimed to investigate the value of individual laboratory tests and combinations of tests for predicting disease severity. METHODS: We retrospectively reviewed 62 patients with space infections in the oral and maxillofacial head and neck regions. Patients were divided into three groups according to severity. Laboratory tests associated with disease severity were identified. RESULTS: As the severity of infection increased, leukocytes, neutrophils, C-reactive protein (CRP), procalcitonin (PCT), soluble interleukin receptor (sILR) 2, IL6, and creatinine (CR) increased. In the ROC analysis of group 1 (moderate infection) versus group 2 (severe infection), the area under the curve (AUC) values for leukocytes (AUC = 0.724), neutrophils (AUC = 0.714), PCT (AUC = 0.762) and a combination of the 3 tests (AUC = 0.768) suggested a strong predictive value. Furthermore, in the ROC analysis of group 2 (severe infection) versus group 3 (extremely severe infection), the AUC values for CRP (AUC = 0.84), PCT (AUC = 0.799), sIL2R (AUC = 0.937), IL6 (AUC = 0.863) and a combination of the four tests (AUC = 0.943) suggested a strong predictive value. CONCLUSIONS: Leukocytes, neutrophils, and PCT were associated with multispace infection and high severity. CRP, PCT, sIL2R, and/or IL6 were associated with extremely severe infections occurring in the oral and maxillofacial head and neck regions.

14.
Angew Chem Int Ed Engl ; 62(22): e202217374, 2023 05 22.
Artículo en Inglés | MEDLINE | ID: mdl-36988087

RESUMEN

To increase the red blood cell (RBC) cryopreservation efficiency by metal-organic frameworks (MOFs), a dimensional reduction approach has been proposed. Namely, 3D MOF nanoparticles are progressively reduced to 2D ultra-thin metal-organic layers (MOLs). We found that 2D MOLs are beneficial for enhanced interactions of the interfacial hydrogen-bonded water network and increased utilization of inner ordered structures, due to the higher surface-to-volume ratio. Specifically, a series of hafnium (Hf)-based 2D MOLs with different thicknesses (monolayer to stacked multilayers) and densities of hydrogen bonding sites have been synthesized. Both ice recrystallization inhibition activity (IRI) and RBCs cryopreservation assay confirm the pronounced better IRI activity and excellent cell recovery efficiency (up to ≈63 % at a very low concentration of 0.7 mg mL-1 ) of thin-layered Hf-MOLs compared to their 3D counterparts, thereby verifying the dimensional reduction strategy to improved cryoprotectant behaviors.


Asunto(s)
Estructuras Metalorgánicas , Estructuras Metalorgánicas/química , Criopreservación/métodos , Crioprotectores/farmacología , Crioprotectores/química , Hielo , Hafnio/química , Eritrocitos
15.
ACS Appl Mater Interfaces ; 15(12): 15768-15774, 2023 Mar 29.
Artículo en Inglés | MEDLINE | ID: mdl-36924193

RESUMEN

Multisource coevaporation is such a promising method for the preparation of perovskite films. However, there is limited research about the effects of the buried interface on thermal-evaporated perovskite light-emitting diodes (PeLEDs). In this study, the effects of buried interfaces on thermal-evaporated all-inorganic perovskite films are systematically investigated. It is found that the low-surface-energy buried interface promotes the formation of columnar grain by suppressing heterogeneous nucleation, and functional groups on the high-surface-energy interface have a significant effect on the actual element ratio of the film. The substrate temperature can affect the nucleation and film-formation kinetics of the columnar grains. As a result of the synergistic strategy, a peak external quantum efficiency (EQE) of 8.6% is achieved in the green PeLEDs with a stable emission peak at 516 nm, which is among the best thermal-evaporated PeLEDs reported. This work provides an insight into the preparation of perovskites by thermal evaporation and builds the groundwork for future studies.

16.
Materials (Basel) ; 16(4)2023 Feb 10.
Artículo en Inglés | MEDLINE | ID: mdl-36837114

RESUMEN

This work investigated the effects of single stress and electro-thermo-mechanical coupling stress on the electrical properties of top-cooled enhancement mode (E-mode) Aluminium Gallium Nitride/Gallium Nitride (AlGaN/GaN) high electron mobility transistor (HEMT) (GS66508T). Planar pressure, linear deformation, punctate deformation, environmental temperature, electro-thermal coupling, thermo-mechanical coupling, and electro-thermo-mechanical coupling stresses were applied to the device. It was found that different kinds of stress had different influence mechanisms on the device. Namely, excessive mechanical pressure/deformation stress caused serious, irrecoverable degradation of the device's leakage current, with the gate leakage current (Ig) increasing by ~107 times and the drain-to-source leakage current (Idss) increasing by ~106 times after mechanical punctate deformation of 0.5 mm. The device characteristics were not restored after the mechanical stress was removed. Compared with three mechanical stresses, environmental thermal stress had a greater influence on the device's transfer characteristic and on-resistance (Ron) but far less influence on Ig and Idss. As was expected, multiple stress coupled to the device promoted invalidation of the device. For more in-depth investigation, finite element simulation carried out with COMSOL was used to analyze the effect of electro-thermo-mechanical coupling stress on top-cooled E-mode AlGaN/GaN HEMT. The results of the experiments and simulation demonstrated that single and coupled stresses, especially mechanical stress coupled with other stresses, degraded the electrical properties or even caused irreversible damage to top-cooled E-mode AlGaN/GaN HEMT. Mechanical stress should be reduced as much as possible in the packaging design, transportation, storage, and application of top-cooled E-mode AlGaN/GaN HEMT.

17.
Chemistry ; 29(30): e202300336, 2023 May 26.
Artículo en Inglés | MEDLINE | ID: mdl-36810906

RESUMEN

Transition metal radical-type carbene transfer catalysis is a sustainable and atom-efficient method to generate C-C bonds, especially to produce fine chemicals and pharmaceuticals. A significant amount of research has therefore been devoted to applying this methodology, which resulted in innovative routes toward otherwise synthetically challenging products and a detailed mechanistic understanding of the catalytic systems. Furthermore, combined experimental and theoretical efforts elucidated the reactivity of carbene radical complexes and their off-cycle pathways. The latter can imply the formation of N-enolate and bridging carbenes, and undesired hydrogen atom transfer by the carbene radical species from the reaction medium which can lead to catalyst deactivation. In this concept paper, we demonstrate that understanding off-cycle and deactivation pathways not only affords solutions to circumvent them, but can also uncover novel reactivity for new applications. In particular, considering off-cycle species involved in metalloradical catalysis can stimulate further development of radical-type carbene transfer reactions.

18.
Adv Mater ; 35(21): e2300244, 2023 May.
Artículo en Inglés | MEDLINE | ID: mdl-36821869

RESUMEN

Most hydrogels become frozen at subzero temperatures, leading to degraded properties and limited applications. Cryoprotectants are massively employed to improve anti-freezing property of hydrogels; however, there are accompanied disadvantages, such as varied networks, reduced mechanical properties, and the risk of cryoprotectant leakage in aqueous conditions. Reported here is the glassy hydrogel having intrinsic anti-freezing capacity and excellent optical and mechanical properties at ultra-low temperatures. Supramolecular hydrogel of poly(acrylamide-co-methacrylic acid) with moderate water content (≈50 wt.%) and dense hydrogen-bond associations is in a glassy state at room temperature. Since hydrogen bonds become strengthened as the temperature decreases, this gel becomes stronger and stiffer, yet still ductile, with Young's modulus of 900 MPa, tensile strength of 30 MPa, and breaking strain of 35% at -45 °C. This gel retains high transparency even in liquid nitrogen. It also exhibits unique phosphorescence due to presence of carbonyl clusters, which is further enhanced at subzero temperatures. Further investigations elucidate that the intrinsic anti-freezing property is related to a fact that most water molecules are tightly bound and confined in the glassy matrix and become non-freezable. This correlation, as validated in several systems, provides a roadmap to develop intrinsic anti-freezing hydrogels for widespread applications at extreme conditions.

19.
Anal Methods ; 15(3): 304-310, 2023 01 19.
Artículo en Inglés | MEDLINE | ID: mdl-36546428

RESUMEN

In this study, a 3D surface-folded composite was prepared in situ as a hydrazine sensor by loading a hybrid film of CoNi-layered double hydroxides (LDHs) with nitrogen-doped carbon dots on self-assembled ZnO microspheres. The nanocomposite was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR), and the electrochemical behavior of the sensors was investigated by cyclic voltammetry (CV), amperometry and electrochemical impedance spectroscopy (EIS). The results showed that ZnO microspheres with nitrogen-doped carbon dots strongly coupled with LDHs can significantly reduce the charge transfer resistance, accelerate the oxidation kinetics of hydrazine, and effectively increase the electrochemically active surface area (ECSA). The sensor achieved ultra-sensitive (13 040 µA mM-1 cm-2 (S/N = 3)) detection of hydrazine in the concentration range of 0.7 µM to 4 mM, exhibited excellent selectivity, reproducibility and high stability, and was successfully applied to the determination of hydrazine in actual environmental water samples and landfill leachate samples.


Asunto(s)
Caracol Conus , Óxido de Zinc , Animales , Carbono/química , Óxido de Zinc/química , Reproducibilidad de los Resultados , Hidrazinas , Nitrógeno
20.
Micromachines (Basel) ; 13(12)2022 Nov 28.
Artículo en Inglés | MEDLINE | ID: mdl-36557400

RESUMEN

To study the working performance of 3D stacked chips, a double-layer stacked GaN MISHEMTs structure was designed to study the electro-thermal characteristics and heat transfer process of stacked chips. Firstly, the electrical characteristics of double-layer and single-layer GaN MISHEMTs are compared at room temperature. Under the same conditions, the output current of double-layer GaN MISHEMTs is twice that of single-layer GaN MISHEMTs, but its off-state current is much higher than that of a single-layer device. Meanwhile, there is no significant difference between the threshold voltages of the double-layer and single-layer GaN MISHEMTs. Then, the effect of temperature on the electrical characteristics of double-layer GaN MISHEMTs is also investigated. When the temperature increased from room temperature to 150 °C, the device's threshold voltage gradually shifted negatively, the output current of the device decreased, and the off-state current of the device increased. Furthermore, a thermal resistance network model has been established to analyze the thermal characteristics of the stacked GaN MISHEMTs. The relative error between the results calculated according to the model and the experimental results does not exceed 4.26%, which verified the correctness and accuracy of the presented model to predict the temperature distribution of the stacked GaN MISHEMTs.

SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA
...