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1.
Adv Sci (Weinh) ; 11(17): e2302988, 2024 May.
Article in English | MEDLINE | ID: mdl-38430538

ABSTRACT

Peripheral nerve injury (PNI) remains a challenging area in regenerative medicine. Nerve guide conduit (NGC) transplantation is a common treatment for PNI, but the prognosis of NGC treatment is unsatisfactory due to 1) neuromechanical unmatching and 2) the intra-conduit inflammatory microenvironment (IME) resulting from Schwann cell pyroptosis and inflammatory-polarized macrophages. A neuromechanically matched NGC composed of regenerated silk fibroin (RSF) loaded with poly(3,4-ethylenedioxythiophene): poly(styrene sulfonate) (P:P) and dimethyl fumarate (DMF) are designed, which exhibits a matched elastic modulus (25.1 ± 3.5 MPa) for the peripheral nerve and the highest 80% elongation at break, better than most protein-based conduits. Moreover, the NGC can gradually regulate the intra-conduit IME by releasing DMF and monitoring sciatic nerve movements via piezoresistive sensing. The combination of NGC and electrical stimulation modulates the IME to support PNI regeneration by synergistically inhibiting Schwann cell pyroptosis and reducing inflammatory factor release, shifting macrophage polarization from the inflammatory M1 phenotype to the tissue regenerative M2 phenotype and resulting in functional recovery of neurons. In a rat sciatic nerve crush model, NGC promoted remyelination and functional and structural regeneration. Generally, the DMF/RSF/P:P conduit provides a new potential therapeutic approach to promote nerve repair in future clinical treatments.


Subject(s)
Fibroins , Nerve Regeneration , Peripheral Nerve Injuries , Animals , Nerve Regeneration/drug effects , Nerve Regeneration/physiology , Rats , Peripheral Nerve Injuries/therapy , Fibroins/chemistry , Fibroins/pharmacology , Disease Models, Animal , Rats, Sprague-Dawley , Schwann Cells/metabolism , Guided Tissue Regeneration/methods , Inflammation , Tissue Scaffolds/chemistry , Sciatic Nerve/injuries
2.
Small ; 20(8): e2306997, 2024 Feb.
Article in English | MEDLINE | ID: mdl-37823688

ABSTRACT

MXenes have demonstrated significant potential in electrochemical energy storage, particularly in supercapacitors, owing to their exceptional properties. The surface terminal groups of MXene play a pivotal role in pseudocapacitive mechanism. Considering the hindered electrolyte ion transport caused by -F terminal groups and the limited ion binding sites associated with -O terminal groups, this study proposes a novel strategy of replacing -F with -N terminal groups. The modulated MXene-N electrode, featuring a substantial number of -N terminal groups, demonstrates an exceptionally high gravimetric capacitance of 566 F g-1 (at a scan rate of 2 mV s-1 ) or 588 F g-1 (at a discharge rate of 1 A g-1 ) in 1 м H2 SO4 electrolyte, and the potential window is significantly increased. Furthermore, subsequent spectra analysis and density functional theory calculations are employed to investigate the mechanism associated with -N terminal groups. This work exemplifies the significance of terminal modulation in the context of electrochemical energy storage.

3.
World J Clin Cases ; 11(32): 7905-7910, 2023 Nov 16.
Article in English | MEDLINE | ID: mdl-38073693

ABSTRACT

BACKGROUND: Gastric duplication cysts are very rare disease that are mainly diagnosed by endoscopic ultrasonographic fine-needle aspiration biopsy. In the past, this disease was usually treated with traditional surgery and rarely with minimally invasive endoscopic surgery. However, minimally invasive endoscopic therapy has many advantages, such as no skin wound, organ preservation, postoperative pain reduction, early food intake, fewer postoperative complications, and shorter post-procedure hospitalization. CASE SUMMARY: We report a case of endoscopic ultrasonography-guided fine-needle aspiration (EUS-FNA) combined with lauromacrogol sclerotherapy for pyloric obstruction due to gastric duplication cysts. CONCLUSION: EUS-FNA combined with lauromacrogol sclerotherapy provides a new option for the treatment of gastrointestinal duplication cysts.

4.
Sheng Wu Yi Xue Gong Cheng Xue Za Zhi ; 40(2): 249-256, 2023 Apr 25.
Article in Chinese | MEDLINE | ID: mdl-37139755

ABSTRACT

Hypertension is the primary disease that endangers human health. A convenient and accurate blood pressure measurement method can help to prevent the hypertension. This paper proposed a continuous blood pressure measurement method based on facial video signal. Firstly, color distortion filtering and independent component analysis were used to extract the video pulse wave of the region of interest in the facial video signal, and the multi-dimensional feature extraction of the pulse wave was preformed based on the time-frequency domain and physiological principles; Secondly, an integrated feature selection method was designed to extract the universal optimal feature subset; After that, we compared the single person blood pressure measurement models established by Elman neural network based on particle swarm optimization, support vector machine (SVM) and deep belief network; Finally, we used SVM algorithm to build a general blood pressure prediction model, which was compared and evaluated with the real blood pressure value. The experimental results showed that the blood pressure measurement results based on facial video were in good agreement with the standard blood pressure values. Comparing the estimated blood pressure from the video with standard blood pressure value, the mean absolute error (MAE) of systolic blood pressure was 4.9 mm Hg with a standard deviation (STD) of 5.9 mm Hg, and the MAE of diastolic blood pressure was 4.6 mm Hg with a STD of 5.0 mm Hg, which met the AAMI standards. The non-contact blood pressure measurement method based on video stream proposed in this paper can be used for blood pressure measurement.


Subject(s)
Blood Pressure Determination , Hypertension , Humans , Algorithms , Blood Pressure/physiology , Blood Pressure Determination/methods , Hypertension/diagnosis
5.
ACS Appl Mater Interfaces ; 14(48): 53658-53666, 2022 Dec 07.
Article in English | MEDLINE | ID: mdl-36400752

ABSTRACT

Silicon oxides (SiOx) are one of the most promising anode materials for next-generation lithium-ion batteries owing to their abundant reserve and low lost and high reversible capacity. However, the practical application of SiOx is still hindered by their intrinsically low conductivity and huge volume change. In this regard, we design a novel anode material in which sheet-like SiOx nanosheets are encapsulated in a unique point-to-plane conductive network composed of graphene flakes and nitrogen-doped carbon spheres. This unique composite structure demonstrates high specific capacity (867.7 mAh g-1 at 0.1 A g-1), superior rate performance, and stable cycle life. The electrode delivers a superior reversible discharge capacity of 595.8 mAh g-1 after 200 cycles at 1.0 A g-1 and 287.5 mAh g-1 after 500 cycles at 5.0 A g-1. This work may shed light on the rational design of SiOx-based anode materials for next-generation high-performance lithium-ion batteries.

6.
Iran J Public Health ; 51(6): 1331-1338, 2022 Jun.
Article in English | MEDLINE | ID: mdl-36447965

ABSTRACT

Background: There are a large number of psychological problems caused by Internet addiction. We aimed to explore the intervention effect of narrative therapy in combination with Pilates exercise on Internet addiction among adolescents. Method: From July 2021 to October 2021, 42 adolescents with Internet addiction selected from four communities in Yiyang City of China were randomly divided into the intervention and control groups with 21 members in each group. The intervention group participated in the intervention of narrative therapy in combination with Pilates exercise eight times, whereas the control group did not receive any intervention. The 12-item General Health Questionnaire, Self-rating Young's Diagnostic Questionnaire of Internet Addiction, and Positive Affect Subscale were used to measure the psychological indexes of the adolescents before and after the intervention. Results: Compared with those in the control group, the adolescents in the intervention group had an obvious decrease in the degree of Internet addiction with a statistically significant difference before and after the intervention (P < 0.001). After the intervention, the intervention group had significantly higher mental health scores and significantly lower scores for anxiety, depression, social dysfunction, and loss of interest than the control group. After the intervention, the intervention group showed an obvious increase in the score for positive affect with a statistically significant difference before and after the intervention (P < 0.001). Conclusion: The intervention method proposed in this study could effectively solve the problem of Internet addiction among adolescents.

7.
Spectrochim Acta A Mol Biomol Spectrosc ; 270: 120811, 2022 Apr 05.
Article in English | MEDLINE | ID: mdl-35016063

ABSTRACT

Near-infrared (NIR) emitting BiVO4:Yb3+,Tm3+ nanoparticles are synthesized by a new solvothermal strategy using solvents of oleic acid and methanol. The obtained BiVO4:Yb3+,Tm3+ samples show an average particle size of ≈164 nm and exhibit an asymmetry monoclinic crystal structure of BiVO4. At NIR excitation of 980 nm, the BiVO4:Yb3+,Tm3+ sample exhibits a nearly single NIR emission at ≈796 nm with extremely weak blue emissions from Tm3+ ions. These high-energy visible emissions are absorbed by the semiconducting host of BiVO4 that possesses a bandgap of ≈2.2 eV. Therefore, the NIR excitation to a single intense NIR emission fluorescent BiVO4 materials could be a potential ideal probe for deep-tissue high-resolution bioimaging. To validate the ability of BiVO4 materials for bio-applications, we conduct the cytotoxicity experiments. The results show that the cytotoxicity of HeLa cells is negligible at a concentration of 0.2 mg/ml of BiVO4:Yb3+,Tm3+ , and the cell viability approaches 90% at a high dosage of 0.5 mg/ml. The Daphnia magna and Zebrafish treated with nanoparticles (0.5 mg/ml) display bright NIR emission without any background, indicating the excellent in vivo fluorescent imaging capacity of BiVO4:Yb3+,Tm3+ nanoparticles. Our findings offer an environment-friendly strategy to synthesize BiVO4 UCL nanophosphors and provide a promising new class of fluorescent probes for biological applications.


Subject(s)
Nanoparticles , Zebrafish , Animals , HeLa Cells , Humans , Nanoparticles/toxicity , Particle Size
8.
IEEE Trans Neural Netw Learn Syst ; 33(2): 577-586, 2022 Feb.
Article in English | MEDLINE | ID: mdl-33079679

ABSTRACT

Finding a desirable sampling estimator has a profound impact on the development of static word embedding models, such as continue-bag-of-words (CBOW) and skip gram (SG), which have been generally accepted as popular low-resource algorithms to generate task-agnostic word representations. Due to the prevalence of large-scale pretrained models, less attention has been paid to these static models in the recent years. However, compared with the dynamic embedding models (e.g., BERT), these static models are straightforward to interpret, cost effective to train, and out-of-box to deploy, thus are still widely used in various downstream models until now. Therefore, it is still of considerable significance to study and improve them, especially the crucial components shared by these static models. In this article, we focus on negative sampling (NS), a key component shared by the sampling-based static models, by investigating and mitigating some critical problems of the sampling core. Concretely, we propose Seeds, a sampling enhanced embedding framework, to learn static word embeddings by a new algorithmic innovation for replacing the NS estimator, in which multifactor global priors are considered dynamically for different training pairs. Then, we implement this framework by four concrete models. For the first two implementations, namely CBOW-GP and SG-GP, both negative words and positive auxiliaries are sampled. And for the other two implementations, CBOW-GN and SG-GN, estimations are simplified by sampling only the negative instances. Extensive experimental results across a variety of standard intrinsic and extrinsic tasks demonstrate that embeddings learned by the proposed models outperform their NS-based counterparts, such as CBOW-NS and SG-NS, as well as other strong baselines.

9.
J Perianesth Nurs ; 37(1): 53-62.e1, 2022 Feb.
Article in English | MEDLINE | ID: mdl-34756625

ABSTRACT

PURPOSE: Identifying factors that place patients at high risk for developing postoperative delirium is an important first step to reduce incidence. Frailty is associated with poor postoperative outcomes. This meta-analysis aims to determine the association between preoperative frailty and postoperative delirium. DESIGN: This is a systematic review and meta-analysis. METHODS: We used PubMed, Scopus, Embase, CINAHL, Cochrane, and Web of Science as databases for the search up to April 23, 2020. We included cohort studies that assessed postoperative delirium as the outcome and described the prevalence of delirium among participants during the postoperative period. Odds ratio and 95% confidence interval were calculated to examine the association. FINDINGS: Twenty cohort studies met our inclusion criteria, which included a total of 4,568 patients. We found that preoperative frailty was significantly associated with an increased risk of postoperative delirium (crude odds ratio: 3.28; 95% confidence interval: 2.51 to 4.28; I2 = 46.7%) (adjusted odds ratio: 2.45; 95% confidence interval: 1.58 to 3.81; I2 = 88.6%). CONCLUSIONS: This meta-analysis showed that preoperative frailty is an independent risk factor for postoperative delirium. In patients undergoing cardiovascular surgery, there is a lower association between frailty and postoperative delirium. In patients with other types of surgery, preoperative frailty is closely related to postoperative delirium.


Subject(s)
Delirium , Frailty , Cohort Studies , Delirium/epidemiology , Delirium/etiology , Frailty/complications , Humans , Incidence , Postoperative Complications/epidemiology , Risk Factors
10.
Small ; 18(4): e2105696, 2022 Jan.
Article in English | MEDLINE | ID: mdl-34837326

ABSTRACT

The oxygen evolution reaction (OER) plays a key role in many electrochemical energy conversion systems, but it is a kinetically sluggish reaction and requires a large overpotential to deliver appreciable current, especially for the non-noble metal electrocatalysts. In this study, the authors report a surface phase engineering strategy to improve the OER performance of transition metal nitrides (TMNs). The iron-nickel nitrides/alloy nanospheres (FeNi3 -N) wrapped in carbon are synthesized, and the optimized FeNi3 -N catalyst displays dual-phase nitrides on the surface induced by atom migration phenomenon, resulting from the different migration rates of metal atoms during the nitridation process. It shows excellent OER performance in alkaline media with an overpotential of 222 mV at 10 mA cm-2 , a small Tafel slope of 41.53 mV dec-1 , and long-term durability under high current density (>0.5 A cm-2 ) for at least 36 h. Density functional theory (DFT) calculations further reveal that the dual-phase nitrides are favorable to decrease the energy barrier, modulate the d-band center to balance the absorption and desorption of the intermediates, and thus promote the OER electrochemical performance. This strategy may shed light on designing OER and other catalysts based on surface phase engineering.

11.
Anim Cells Syst (Seoul) ; 25(5): 283-295, 2021.
Article in English | MEDLINE | ID: mdl-34745435

ABSTRACT

Selenium (Se) is a vital element of life, which has an important impact on the growth, development, production performance and stress-tolerance of animals. However, it is not entirely clear that how exactly Se works during these processes. Herein, we investigate the role of Se in regulating the functions of goat mammary epithelial cells (GMECs) under heat-stress condition. We found that heat stress caused ferroptosis-like death in GMECs, manifested by a robust increase in iron ion concentration, reactive oxygen species (ROS) and cell death ratio, and a decrease in the activity of superoxide dismutase (SOD) and expression level of glutathione peroxidases 4 (GPX4). Se incubation had no obvious effect on GMEC viability, but alleviated heat-stress-induced ferroptosis-like cell death and improved GPX4 expression and SOD activity in a dose-dependent manner. Also, we found that overexpression of GPX4 could improve the activity of SOD. And Se incubation inhibited activation of mTOR signaling in heat-stress-induced GMECs, which could be eliminated by the mTOR activator MHY1485, and treatment with mTOR inhibitor AY-22989 had the same effect as Se. In conclusion, Se improves GPX4 expression and SOD activity and inhibits the activation of mTOR to alleviate heat-stress-induced ferroptosis-like death in GMECs, which may be a protective agent for heat stress in goats.

12.
Bioinspir Biomim ; 16(5)2021 08 11.
Article in English | MEDLINE | ID: mdl-34130274

ABSTRACT

Soft grippers have exhibited considerable advantages owing to their flexible deformation, compliant operation, and safe interaction with objects. The ability to grip solid and liquid objects can greatly expand the application range of the soft grippers. Dogs stick out their tongues and then curl them backward to form a ladle shape for eating food and drinking water. The large extension ratio and the ladling motion of the tongues endow dogs with flexible operations for both solids and liquids. In this work, inspired by both the extending and ladling motions of dog tongues, a bionic soft tongue with the capability of handling solid and liquid objects was designed. The bionic soft tongue was composed of a tongue base and a tongue tip, which were driven by pneumatics and shape memory alloy wires, respectively. The tongue base was capable of linearly elongating and contracting with a considerable scale, while the tongue tip could be curled into a ladle shape to grasp objects. The dynamic model of the tongue base was developed and then extended to build the model-based feedback controller for the motion control. A phase dynamic model of the tongue tip was simulated for structural optimization. With the model-based feedback controller, the bionic soft tongue could achieve a fast step response and precise position control. Experimental results showed that the bionic soft tongue could grasp different kinds of objects, including of water, rice, and gel balls. This work is expected to expand the application scope of soft grippers.


Subject(s)
Bionics , Robotics , Animals , Dogs , Hand Strength , Shape Memory Alloys , Tongue
13.
Mar Pollut Bull ; 168: 112424, 2021 Jul.
Article in English | MEDLINE | ID: mdl-33975157

ABSTRACT

It has been 14 years since the world's largest Ulva bloom appeared in the Yellow Sea, China in 2007. Although it is clear that the Ulva bloom originates from the culture system of Porphyra yezoensis (Nori) in the southern Yellow Sea, how to control it is still little understood. Since overwintering banks played a crucial role in the development of spring population of green algae on the cultivation ropes, here, a promising method was presented to prevent the development of Ulva bloom by the inactivation of the overwintering banks of green algae on the P. yezoensis cultivation ropes during February and early March. Chlorine dioxide, an environment-friendly disinfectant was used as algaecide with dosage of no lower than 40 mg/L at the contact time of 1 min. The overwintering green algae gradually disappeared within two weeks after the treatment. Furthermore, the growth of spring population of green algae on the cultivation ropes was effectively inhibited for at least eight weeks, which contribute to prevent the formation of floating populations during cultivation facilities collection. It was expected that the present method, if to be applied in the P. yezoensis cultivation areas in southern Yellow Sea, may mitigate the magnitude of the Ulva blooms in the Yellow Sea at a lower cost.


Subject(s)
Chlorophyta , Porphyra , Ulva , China , Eutrophication
15.
J Integr Neurosci ; 20(4): 977-984, 2021 Dec 30.
Article in English | MEDLINE | ID: mdl-34997720

ABSTRACT

Major depression disorder is one of the diseases with the highest rate of disability and morbidity and is associated with numerous structural and functional differences in neural systems. However, it is difficult to analyze digital medical imaging data without computational intervention. A voxel-wise densely connected convolutional neural network, Three-dimensional Densenet (3D-DenseNet), is proposed to mine the feature differences. In addition, a novel transfer learning method, called Alzheimer's Disease Neuroimaging Initiative Transfer (ADNI-Transfer), is designed and combined with the proposed 3D-DenseNet. The experimental results on a database that contains 174 subjects, including 99 patients with major depression disorder and 75 healthy controls, show that large changes in brain structures between major depressive disorder patients and healthy controls mainly are located in the regions including superior frontal gyrus, dorsolateral, middle temporal gyrus, middle frontal gyrus, postcentral gyrus, inferior temporal gyrus. In addition, the proposed deep learning network can better extract different features of brain structures between major depressive disorder patients and healthy controls and achieve excellent classification results of major depressive disorder. At the same time, the designed transfer learning method can further improve classification performance. These results verify that our proposed method is feasible and valid for diagnosing and analyzing major depression disorder.


Subject(s)
Cerebral Cortex/diagnostic imaging , Deep Learning , Depressive Disorder, Major/diagnostic imaging , Magnetic Resonance Imaging/methods , Neuroimaging/methods , Adult , Feasibility Studies , Female , Humans , Image Processing, Computer-Assisted/methods , Image Processing, Computer-Assisted/standards , Magnetic Resonance Imaging/standards , Male , Middle Aged , Neuroimaging/standards , Reproducibility of Results , Young Adult
16.
Anal Methods ; 12(23): 2985-2994, 2020 06 18.
Article in English | MEDLINE | ID: mdl-32930158

ABSTRACT

The spread of infectious diseases among aquaculture species has a serious impact on the aquaculture industry. Simple, specific and low-cost detection methods are urgently needed for early diagnosis and timely treatment, particularly for on-site identifying and tracking of pathogens. Vibrio splendidus (V. splendidus) is regarded as one of the main pathogenic bacteria causing skin ulcerative syndrome in cultured sea cucumbers, leading to massive mortality and severe economic losses. We herein present a microfluidic-based real-time fluorogenic loop-mediated isothermal amplification (LAMP) system for simple and reliable detection of V. splendidus. A LAMP primer set with six primers (arsB1) specifically targeting the arsB gene of V. splendidus was successfully designed and tested on the portable microfluidic system for the first time. Only a single step of sample loading using a pipette is required to fill an array of reaction wells (with 10 or 18 wells) in a disposable chip for multiplex detection. A dedicated plastic shell is then utilized to tightly seal the openings of the chip by buckling to prevent contamination and evaporation. Up to four chips (one sample per chip) can be held in the stand-alone and inexpensive microdevice simultaneously, enabling on-demand detection of multiple samples in a single run. Reproducible (relatively low intra- and inter-chip variability) and sensitive (as few as ∼20 CFU, Colony-Forming Units, per reaction well) on-chip arsB1-LAMP assay was demonstrated by using diluted lysate of V. splendidus. A linear standard curve (R2 > 0.98) was attained over the template concentration range of 5 × 103 to 5 × 106 CFU mL-1. V. splendidus can be detected in samples containing different bacteria, indicating the feasibility of the portable microfluidic LAMP system for parallel detection of multiple bacterial pathogens. The proposed on-chip LAMP assay is simple to operate, reliable for amplification, flexible in detection and cost-effective in instrumentation and testing, holding great potential for on-site rapid detection and routine monitoring of aquaculture pathogens.


Subject(s)
Microfluidics , Nucleic Acid Amplification Techniques , Molecular Diagnostic Techniques , Vibrio
17.
Nat Prod Bioprospect ; 10(3): 141-152, 2020 Jun.
Article in English | MEDLINE | ID: mdl-32415420

ABSTRACT

Betulin (BE) has exceedingly become a potential natural product, providing multiple pharmacological and biological activities, including anti-cancer, anti-viral, and anti-inflammatory benefits. Previous research indicated that the solvatomorphism of BE can easily occur through crystallization with different organic solvents. This property of BE can directly affect its extraction, isolation, and preparation process. In this study, a system of thermogravimetry (TG)-differential thermal analysis (DTA) coupled with mass spectrometry (MS) with electron ionization (EI) and photoionization (PI) capability, equipped with the skimmer-type interface (i.e., skimmer-type interfaced TG-DTA-EI/PI-MS system), as a real-time and onsite analysis technique, was employed. Then, four solvatomorphs of BE, namely, with pyridine and water (A), sec-butanol (B), n,n-dimethylformamide (DMF) (C), and isopropanol (V), were analyzed for the first time. Finally, five kinds of the main volatile gaseous species, including H2O, pyridine, sec-butanol, DMF, and isopropanol, were identified clearly. Furthermore, the multi-step desolvation processes of the four solvatomorphs of BE were revealed by this system for the first time. This system showed great potential for the rapid and accurate analysis of various solvatomorphs of natural products.

18.
Mar Pollut Bull ; 149: 110532, 2019 Dec.
Article in English | MEDLINE | ID: mdl-31543479

ABSTRACT

This study considered the stability of nickel oxide nanoparticles (nNiO) in seawater including their ability of aggregation and ion release. Furthermore, the relationship between these properties and their toxicity on marine algae Chlorella vulgaris was investigated. The results showed nNiO inhibited the growth of algal cells and decreased their chlorophyll content, which was due to the shading effects by aggregation of nNiO in seawater. Moreover, the release of Ni2+ depended on concentration of the nNiO solution. About 1.63% Ni2+ (varied from 0.89 to 3.63%) was detected and it may mediate the generation of ROS under both visible light and ultraviolet (UV) irradiation, which resulted in oxidative stress in algae. Therefore, the stability of nNiO in water affected its toxicity, which should be considered when assessing the nano-pollution risks in aquatic ecosystem.


Subject(s)
Chlorella vulgaris/drug effects , Metal Nanoparticles/chemistry , Metal Nanoparticles/toxicity , Nickel/toxicity , Water Pollutants, Chemical/toxicity , Chlorella vulgaris/growth & development , Chlorella vulgaris/metabolism , Chlorophyll/metabolism , Hydrogen-Ion Concentration , Light , Nickel/chemistry , Oxidation-Reduction , Oxidative Stress/drug effects , Reactive Oxygen Species , Seawater/chemistry , Ultraviolet Rays , Water Pollutants, Chemical/chemistry
19.
Dalton Trans ; 48(38): 14299-14305, 2019 Oct 14.
Article in English | MEDLINE | ID: mdl-31453996

ABSTRACT

A thorough structural exploration was performed for MgB6 combining the global structure searching method with first-principles calculations. Besides the known Cmcm phase, new phases, i.e. I4/mmm, C2/m-I, C2/m-II and P21/m, were predicted to be stable in the pressure range of 18-100 GPa. Unexpectedly, Cmcm-MgB6 was found to be a semiconductor with an indirect band gap of 0.38 eV with the HSE06 functional, in good agreement with the experimental finding. I4/mmm-MgB6 stabilized above 18 GPa exhibits semimetallic behaviour with a topological node-line near the Fermi level. Consequently, C2/m-I MgB6 with a sandwich structure similar to MgB2 is predicted to be a superconductor with a critical temperature (Tc) of 9.5 K. By analysing the electronic structure, the intriguing semiconductor-semimetal-superconductor transition may be ascribed to the delocalization of more B-p electrons in the boron sublattice. The novel functions uncovered for MgB6 may inspire more efforts to discover materials with intriguing properties.

20.
Inorg Chem ; 58(15): 10295-10303, 2019 Aug 05.
Article in English | MEDLINE | ID: mdl-31329423

ABSTRACT

To construct desired metal-organic framework (MOF) sensors, the predesigned functionalized ligands 2,5-bis(2',5'-dicarboxylphenyl)pyridine (L-N) and 2,5-bis(2',5'-dicarboxylphenyl)difluorobenzene (L-F) with pyridine- and fluorine-decorated tetracarboxylic acids were used, and two stable terbium-organic frameworks, H3O[(Tb(L-N)(H2O)2]·2H2O (Tb-N) and [Tb3(L-F)2(HCOO)(H2O)4]·6H2O (Tb-F), have been synthesized. The structures of Tb-N and Tb-F contain 1D open channels, which are functionalized by pyridine N or F atoms, respectively. Both of them show intense fluorescence in water and exhibit excellent selectivity and sensitivity to Fe3+ ions. The effects of different functional group sites on the stability and fluorescence sensing performance of MOFs have also been studied. In addition, a gas adsorption study demonstrates that Tb-N is capable of adsorbing C2H2 over CH4 selectively.

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