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1.
Cytotechnology ; 76(4): 403-414, 2024 Aug.
Article in English | MEDLINE | ID: mdl-38933875

ABSTRACT

Potential role and associated mechanisms of Annexin A8 (ANXA8), a member of the Annexins family, in cervical squamous cell carcinoma (CESC) are still unclear, despite being upregulated in various malignant tumors. Here, we observed a notably elevated expression of ANXA8 in CESC cells. The inhibition of ANXA8 amplified the susceptibility of CESC cells to Erastin and sorafenib-induced ferroptosis, whereas it exerted minimal influence on DPI7 and DPI10-induced ferroptosis. The results from the Fe2+ concentration assay showed no significant correlation between ANXA8 gene knockdown and intracellular Fe2+ concentration induced by ferroptosis inducers. Western blot analysis demonstrated that the knockdown of ANXA8 did not alter ACSL4 and LPCAT levels under ferroptosis-inducing conditions, but it did result in a reduction in intracellular GSH levels induced by the ferroptosis inducer. Subsequently, we identified TFAP2A as an upstream transcription factor of ANXA8, which plays a role in regulating cell ferroptosis. The knockdown of TFAP2A significantly elevated MDA levels and depressed GSH levels in the presence of a ferroptosis inducer, thereby inhibiting cell ferroptosis. However, this inhibitory effect could be reversed by ANXA8 overexpression. Therefore, our research suggests that the TFAP2A/ANXA8 axis exerts regulatory control over ferroptosis in CESC cells by mediating GSH synthesis in System Xc.

2.
ACS Appl Mater Interfaces ; 16(8): 9768-9786, 2024 Feb 28.
Article in English | MEDLINE | ID: mdl-38349802

ABSTRACT

This study aims to overcome the drawbacks associated with hydroxyapatite (HAP) dense structures after sintering, which often result in undesirable features such as large grain size, reduced porosity, high crystallinity, and low specific surface area. These characteristics hinder osseointegration and limit the clinical applicability of the material. To address these issues, a new method involving the preparation of hollow hydroxyapatite (hHAP) microspheres has been proposed. These microspheres exhibit distinctive traits including weak crystallization, high specific surface area, and increased porosity. The weak crystallization aligns more closely with early mineralization products found in the human body and animals. Moreover, the microspheres' high specific surface area and porosity offer advantages for protein loading and facilitating osteoblast attachment. This innovative approach not only mitigates the limitations of conventional HAP structures but also holds the potential for improving the effectiveness of hydroxyapatite in biomedical applications, particularly in enhancing osseointegration. Three-dimensional printed hHAP/chitosan (CS) scaffolds with different hHAP concentration gradients were manufactured, and the physical and biological properties of each group were systematically evaluated. In vitro and in vivo experiments show that the hHAP/CS scaffold has excellent performance in bone remodeling. Furthermore, in-scaffold components, hHAP and CS were cocultured with bone marrow mesenchymal stem cells to explore the regulatory role of hHAP and CS in the process of bone healing and to reveal the cell-level specific regulatory network activated by hHAP. Enrichment analysis showed that hHAP can promote bone regeneration and reconstruction by recruiting calcium ions and regulating inflammatory reactions.


Subject(s)
Chitosan , Durapatite , Animals , Humans , Durapatite/pharmacology , Durapatite/chemistry , Tissue Scaffolds/chemistry , Calcium , Osteogenesis , Bone Regeneration/physiology , Chitosan/chemistry , Printing, Three-Dimensional , Porosity , Ions
3.
Sci Rep ; 14(1): 130, 2024 01 02.
Article in English | MEDLINE | ID: mdl-38167649

ABSTRACT

Ovarian cancer (OVCA), a prevalent gynecological malignancy, ranks as the fourth most common cancer among women. Mitotic Arrest Deficient 2 Like 2 (MAD2L2), a chromatin-binding protein and a component of DNA polymerase ζ, has been previously identified as an inhibitor of tumor growth in colorectal cancer. However, the roles of MAD2L2 in OVCA, including its expression, impact, and prognostic significance, remain unclear. We employed bioinformatics tools, Cox Regression analysis, and in vitro cell experiments to investigate its biological functions. Our findings reveal that MAD2L2 typically undergoes genomic alterations, such as amplifications and deep deletions. Moreover, we observed an overexpression of MAD2L2 mRNA in OVCA patients, correlating with reduced survival rates, particularly in those with Grade IV tumors. Furthermore, analysis of mRNA biofunctions indicated that MAD2L2 is predominantly localized in the organellar ribosome, engaging mainly in NADH dehydrogenase activity. This was deduced from the results of gene ontology enrichment analysis, which also identified its role as a structural constituent in mitochondrial translation elongation. These findings were corroborated by KEGG pathway analysis, further revealing MAD2L2's involvement in tumor metabolism and the cell death process. Notably, MAD2L2 protein expression showed significant associations with various immune cells, including CD4+T cells, CD8+T cells, B cells, natural killer cells, and Myeloid dendritic cells. Additionally, elevated levels of MAD2L2 were found to enhance cell proliferation and migration in OVCA cells. The upregulation of MAD2L2 also appears to inhibit the ferroptosis process, coinciding with increased mTOR signaling activity in these cells. Our study identifies MAD2L2 as a novel regulator in ovarian tumor progression and offers new insights for treating OVCA.


Subject(s)
Ovarian Neoplasms , Humans , Female , Ovarian Neoplasms/pathology , Proteins , Neoplastic Processes , Cell Proliferation/genetics , RNA, Messenger/genetics , Cell Line, Tumor , Mad2 Proteins/genetics , Mad2 Proteins/metabolism
4.
Women Health ; 64(2): 109-120, 2024 02 07.
Article in English | MEDLINE | ID: mdl-38148599

ABSTRACT

Endometriosis (EMS) is a chronic inflammatory disorder of high incidence that causes serious reproductive consequences. High estrogen production is a consistently observed endocrine feature of EMS. The present study aims to probe the molecular mechanism of G protein-coupled estrogen receptor 1 (GPER) in the invasion and migration of ectopic endometrial stromal cells (Ect-ESCs) and provides a new rationale for EMS treatment. Eutopic and ectopic endometrial tissues were collected from 41 EMS patients, and primary ESCs were separated. GPER, miR-16-5p, and miR-103a-3p levels in cells and tissues were determined by qRT-PCR or Western blot assay. Cell viability, proliferation, invasion, and migration were evaluated by CCK-8, colony formation, and Transwell assays. The upstream miRNAs of GPER were predicted by databases, and dual-luciferase assay was performed to validate the binding of miR-16-5p and miR-103a-3p to GPER 3'UTR. GPER was highly expressed in EMS tissues and Ect-ESCs. Inhibition of GPER mitigated the proliferation, invasion, and migration of Ect-ESCs. GPER was regulated by miR-16-5p and miR-103a-3p. Overexpression of miR-16-5p and miR-103a-3p negatively regulated GPER expression and inhibited the invasion and migration of Ect-ESC. In conclusion, GPER promoted the invasion and migration of Ect-ESCs, which can be reversed by upstream miR-16-5p and miR-103a-3p.


Subject(s)
Endometriosis , MicroRNAs , Female , Humans , Cell Movement/genetics , Estrogens , MicroRNAs/genetics , MicroRNAs/metabolism , Stromal Cells/metabolism
5.
Materials (Basel) ; 16(17)2023 Aug 28.
Article in English | MEDLINE | ID: mdl-37687575

ABSTRACT

Strain-controlled low-cycle fatigue (LCF) tests and stress-controlled creep-fatigue interaction (CFI) tests on the FGH96 superalloy were carried out at 550 °C to obtain the cyclic softening/hardening characteristics at different strain amplitudes and ratcheting strain characteristics under different hold time. The failure mechanism of the FGH96 superalloy under different loading conditions was analyzed through fracture observations. The results show that the FGH96 superalloy exhibits different cyclic softening/hardening characteristics at different strain amplitudes, and the introduction of the hold time at peak stress exacerbates the ratcheting strain of the FGH96 superalloy under asymmetric stress cycles. Fracture observations show that the magnitude of the strain amplitude, high-temperature oxidation, and the introduction of the hold time will affect the mechanical properties of the FGH96 superalloy and change its fracture mode.

6.
Front Mol Biosci ; 10: 1190683, 2023.
Article in English | MEDLINE | ID: mdl-37206890

ABSTRACT

Renal injury is one of the most common clinical manifestations of patients with hyperuricaemia/gout. The precise pathophysiological mechanism(s) for the renal injury is still unknown. Furthermore, it is also unclear whether the clinical therapies (e.g., colchicine and febuxostat) could prevent its progression or not. Lipids are involved in almost all of important biological processes and play critical roles in maintaining the renal functions. Herein, shotgun lipidomics was performed for class-targeted lipid analysis of cellular lipidomes in renal tissue of a gouty model induced by combination of monosodium urate crystals injection and high-fat diet feeding with/without treatment with either colchicine or febuxostat. Serum uric acid (UA), proinflammatory cytokines (i.e., TNF-α and IL-6), xanthine oxidase activity, footpad swelling, and pain threshold were determined to evaluate the gouty severity. Renal histopathological changes, blood urea nitrogen, creatinine, and kidney index were used to reflect renal injury. Lipidomics analysis revealed that altered triacylglycerol (TAG) profile, impaired mitochondrial function resulted by decreased tetra 18:2 cardiolipin, reduced 4-hydroxyalkenal (HNE) species, and elevated lysophospholipids were already present in the kidneys at early stage of renal injury, probably contributing to its occurrence and development. In addition to significantly reduce the UA level and relief the gouty severity, treatment with either colchicine or febuxostat could restore HNE bioavailability, thereby delaying the progression of renal injury. However, both of them could not recover the altered TAG profile and the impaired mitochondrial function, indicating that treatment with either of them could not completely prevent the development of renal injury in the gouty model.

7.
Proc Natl Acad Sci U S A ; 119(32): e2204630119, 2022 Aug 09.
Article in English | MEDLINE | ID: mdl-35914123

ABSTRACT

The effect of Lifshitz transition on thermodynamics and superconductivity in hole-doped cuprates has been heavily debated but remains an open question. In particular, an observed peak of electronic specific heat is proposed to originate from fluctuations of a putative quantum critical point p* (e.g., the termination of pseudogap at zero temperature), which is close to but distinguishable from the Lifshitz transition in overdoped La-based cuprates where the Fermi surface transforms from hole-like to electron-like. Here we report an in situ angle-resolved photoemission spectroscopy study of three-dimensional Fermi surfaces in La2-xSrxCuO4 thin films (x = 0.06 to 0.35). With accurate kz dispersion quantification, the said Lifshitz transition is determined to happen within a finite range around x = 0.21. Normal state electronic specific heat, calculated from spectroscopy-derived band parameters, reveals a doping-dependent profile with a maximum at x = 0.21 that agrees with previous thermodynamic microcalorimetry measurements. The account of the specific heat maximum by underlying band structures excludes the need for additionally dominant contribution from the quantum fluctuations at p*. A d-wave superconducting gap smoothly across the Lifshitz transition demonstrates the insensitivity of superconductivity to the dramatic density of states enhancement.

8.
Front Cell Infect Microbiol ; 12: 913393, 2022.
Article in English | MEDLINE | ID: mdl-36034715

ABSTRACT

RNA-sequencing (RNA-seq) is a versatile, high-throughput technology that is being widely employed for screening differentially expressed genes (DEGs) in various diseases. Echinococcosis, a globally distributed zoonosis, has been reported to impose a heavy disease burden in pastoral areas of China. Herein we aimed to explore the molecular mechanisms underlying echinococcosis. In this study, peripheral blood samples were collected from six patients with alveolar echinococcosis (AE), six patients with cystic echinococcosis (CE), and six healthy controls. RNA-Seq (mRNA) was performed to detect gene transcript and expression levels, and DEGs were subjected to bioinformatic analyses. In comparison with healthy controls, 492 DEGs (270 upregulated, 222 downregulated) were found in the AE group and 424 DEGs (170 upregulated, 254 downregulated) were found in the CE group (|log2 (fold change)| > 1 and P < 0.05). Further, 60 genes were upregulated and 39 were downregulated in both the AE and CE groups. Gene ontology enrichment analysis indicated that DEGs were mainly involved in molecular functions, including extracellular space, extracellular region, organ and system development, and anatomical structure development. Protein-protein interaction (PPI) networks were constructed to depict the complex relationship between DEGs and interacting proteins.


Subject(s)
Echinococcosis , Transcriptome , Gene Expression Profiling , Gene Expression Regulation, Neoplastic , Gene Regulatory Networks , Humans
9.
Crit Care Med ; 50(3): 440-448, 2022 03 01.
Article in English | MEDLINE | ID: mdl-34637424

ABSTRACT

OBJECTIVES: To determine the impact of coronavirus disease 2019 on burnout syndrome in the multiprofessional ICU team and to identify factors associated with burnout syndrome. DESIGN: Longitudinal, cross-sectional survey. SETTING: All adult ICUs within an academic health system. SUBJECTS: Critical care nurses, advanced practice providers, physicians, respiratory therapists, pharmacists, social workers, and spiritual health workers were surveyed on burnout in 2017 and during the coronavirus disease 2019 pandemic in 2020. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Burnout syndrome and contributing factors were measured using the Maslach Burnout Inventory of Health and Human Service and Areas of Worklife Survey. Response rates were 46.5% (572 respondents) in 2017 and 49.9% (710 respondents) in 2020. The prevalence of burnout increased from 59% to 69% (p < 0.001). Nurses were disproportionately impacted, with the highest increase during the pandemic (58-72%; p < 0.0001) with increases in emotional exhaustion and depersonalization, and personal achievement decreases. In contrast, although burnout was high before and during coronavirus disease 2019 in all specialties, most professions had similar or lower burnout in 2020 as they had in 2017. Physicians had the lowest rates of burnout, measured at 51% and 58%, respectively. There was no difference in burnout between clinicians working in ICUs who treated coronavirus disease 2019 than those who did not (71% vs 67%; p = 0.26). Burnout significantly increased in females (71% vs 60%; p = 0.001) and was higher than in males during the pandemic (71% vs 60%; p = 0.01). CONCLUSIONS: Burnout syndrome was common in all multiprofessional ICU team members prior to and increased substantially during the pandemic, independent of whether one treated coronavirus disease 2019 patients. Nurses had the highest prevalence of burnout during coronavirus disease 2019 and had the highest increase in burnout from the prepandemic baseline. Female clinicians were significantly more impacted by burnout than males. Different susceptibility to burnout syndrome may require profession-specific interventions as well as work system improvements.


Subject(s)
Burnout, Professional/epidemiology , COVID-19/epidemiology , Critical Care/statistics & numerical data , Intensive Care Units/statistics & numerical data , Personnel, Hospital/psychology , Adult , Critical Care Nursing/statistics & numerical data , Cross-Sectional Studies , Female , Humans , Longitudinal Studies , Male , Middle Aged , Pandemics , Patient Care Team/statistics & numerical data , Prevalence , SARS-CoV-2
10.
3 Biotech ; 11(7): 323, 2021 Jul.
Article in English | MEDLINE | ID: mdl-34194907

ABSTRACT

The present study was designed to evaluate the anticancer effects of withaferin A against the human endometrial cancer via modulation of transforming growth factor-ß (TGF-ß) signalling. The results of the present study revealed that withaferin A exerts a dose and time-dependent antiproliferative effects against the human KLE endometrial cancer cells with comparatively lower toxicity against the THESCs normal cells. The IC50 of withaferin A against the KLE endometrial cancer cells was found to 10 µM. The results showed that withaferin A induced apoptosis and G2/M cell cycle arrest of the KLE cells which was associated with alteration of the apoptosis and cell cycle related proteins. In addition, the transwell assays showed that the migration and invasion of the KLE cells were inhibited by 53 and 40%, respectively. Finally, the effects of withaferin A were also examined on the TGF-ß signalling pathway. The results showed that withaferin A blocked TGF-ß-dependent Smad2 phosphorylation and expression of other TGF-ß-related proteins in KLE cells. Summing up, the results suggest that withaferin A inhibits the proliferation of the human endometrial carcinoma via TGF-ß signalling.

11.
Rev Sci Instrum ; 92(2): 025108, 2021 Feb 01.
Article in English | MEDLINE | ID: mdl-33648077

ABSTRACT

To use acoustic-emission technology to detect leaks inside valves, the necessary first step is to model the valve-internal-leakage acoustic-emission signal (VILAES) mathematically. A multi-variable classification model that relates the VILAES characteristics and the leakage rate under varying pressure is built by combining time-frequency domain characteristics and the random-forest method. A Butterworth bandpass filter is used to preprocess the VILAES from a liquid medium, and the best frequency band for filtering is determined as being 140 kHz-180 kHz. Then, (i) the standard deviation, (ii) root mean square, (iii) wavelet packet entropy, (iv) peak standard-deviation probability density, and (v) spectrum area are calculated as the VILAES characteristics, and six parameters-the pressure and the five VILAES characteristics-are used as the inputs for the random-forest classification model. Analysis shows that the five VILAES characteristics increase with an increase in the leakage rate. The multi-variable classification model is established by random forest to determine whether the valve leakage is small, medium, or large. The random forest uses many decision trees to predict the final result. For the same experimental data, the accuracy and operating time of the multi-variable classification model are compared with those of a support-vector-machine classification method for the bandpass and wavelet packet filtering preprocessing methods. The results show that the modeling method based on the combination of time-frequency characteristics and random forest has shorter operating time and higher accuracy.

12.
Rev Sci Instrum ; 92(1): 015105, 2021 Jan 01.
Article in English | MEDLINE | ID: mdl-33514197

ABSTRACT

Ultrasonic gas flow meters are especially suitable for measurement in pipelines with large diameters. However, on the one hand, it is difficult to find a stable feature point to calculate the duration of propagation of the ultrasonic signal, through which we can obtain the real-time flow rate of the gas, and on the other hand, the computation incurred by signal processing methods to this end is burdensome and affects the real-time performance of the flow meter. To solve these problems, this study examines the characteristics of the stability of the echo signal and patterns of variation in the echo contour at different flow rates of gas. We found that peak points of the middle part of the rising segment of the echo signal were relatively stable, and the slope of the envelope of this part was always relatively large but constant, which indicates that peak points in this part were approximately distributed along a straight line. This finding is used to develop a signal processing method based on the connection fitting of the echo peak point with a large slope. This method is easy to implement, incurs a small amount of calculation, and has strong anti-interference ability. Moreover, it can guide research on signal processing methods and the stability of the echo signal. The proposed method was implemented on a dual-core hardware system, and the results of calibration show that it can attain 1.0-level accuracy over a measurable range of 30 m3/h-1100 m3/h.

13.
Int J Parasitol ; 51(2-3): 159-166, 2021 02.
Article in English | MEDLINE | ID: mdl-33220298

ABSTRACT

Human alveolar echinococcosis (AE) is considered a neglected zoonotic disease by the World Health Organization (WHO). The causative pathogen, Echinococcus multilocularis, lives as an adult tapeworm in the intestinal tract of canines. AE was identified as an emerging public health issue in Tibetan communities of Shiqu County 20 years ago. On St. Lawrence Island, Alaska (USA), in the 1980s peri-domestic transmission of E. multilocularis was controlled by regular deworming of owned dogs over a 10-year period. In Tibetan communities, on the Tibetan Plateau, control of E. multilocularis transmission is challenging due to the continental setting, complex epidemiology, disease ecology, geography, and socio-cultural factors. However, a control programme based on deworming owned dogs using praziquental (PZQ) has been carried out since 2006. Assessment was conducted in townships where baseline data were available 10 years prior. Purging of dogs by oral administration of arecoline was used to measure E. multilocularis prevalence, trapping small mammals around communities was employed to assess the change in infection of pikas and voles, and analysis of human AE abdominal ultrasound-based data was used to understand the change in prevalence in the past decade. In all three evaluated townships, the E. multilocularis prevalence in owned dogs was significantly (P < 0.01) reduced from 7.23% (25/346) during 2000-2003 to 0.55% (1/181) in 2016. Human AE ultrasound-based prevalence (adjusted for age and sex) in five evaluated townships decreased significantly (P < 0.01) from 6.25% (200/3,198) during 2000-2002 to 3.67% (706/19,247) during 2015-2017. The 2016 prevalence of E. multilocularis metacestodes in small mammal intermediate hosts was not significantly different from the prevalence in 2008. The control programme was effective in reducing E. multilocularis infection in owned dogs and human AE prevalence, but did not significantly impact infection in wildlife intermediate hosts.


Subject(s)
Dog Diseases , Echinococcosis , Echinococcus multilocularis , Animals , China/epidemiology , Dog Diseases/drug therapy , Dog Diseases/epidemiology , Dog Diseases/prevention & control , Dogs , Echinococcosis/drug therapy , Echinococcosis/epidemiology , Echinococcosis/prevention & control , Prevalence , Tibet
14.
Cancer Manag Res ; 13: 9329-9343, 2021.
Article in English | MEDLINE | ID: mdl-34992456

ABSTRACT

BACKGROUND: Mounting evidence indicates altered circadian rhythm represents a critical factor affecting carcinogenesis and tumor progression. The circadian gene neuronal PAS domain protein 2 (NPAS2) constitutes a newly discovered prognostic biomarker. NPAS2 dysregulation is found in multiple malignancies, although its functions in uterine corpus endometrial carcinoma (UCEC) remain largely unknown. OBJECTIVE: To evaluate NPAS2's roles in UCEC and to explore the underlying mechanisms. METHODS: NPAS2 transcription levels, patient prognosis, different clinical stages and target microRNAs in UCEC cases were comparatively assessed based on public databases, including UALCAN, GEPIA, TIMER, Kaplan-Meier plotter, starBase database, LinkedOmics and String. Then, qRT-PCR and immunohistochemical analysis were applied to analyze the expression of NPAS2 in UCEC tissue samples. CCK-8, clonogenic assay and flow cytometry were carried out for detecting cell viability, colony formation ability and cell apoptosis, respectively. RESULTS: NPAS2 was upregulated in tissue samples from UCEC cases compared with the corresponding control specimens. NPAS2 overexpression was associated with decreased overall (OS), disease free (DFS) and relapse free (RFS) survival in UCEC. In addition, NPAS2 overexpression was associated with clinical stage, tumor grade, estrogen receptor status, myometrial invasion in UCEC. Furthermore, NPAS2 knockdown or overexpression altered cell proliferation and apoptosis in UCEC. Moreover, NPAS2 showed significant negative correlations with miR-17-5p and miR-93-5p, and positive correlations with miR-106a-5p and miR-381-3p in UCEC. CONCLUSION: NPAS2 overexpression is associated with poor prognosis and clinicopathological characteristics in UCEC and promotes proliferation and colony formation while inhibiting apoptosis. Finally, NPAS2 is associated with several miRNAs in UCEC.

15.
Onco Targets Ther ; 13: 4843-4853, 2020.
Article in English | MEDLINE | ID: mdl-32547110

ABSTRACT

BACKGROUND: miRNA expression acts as a potential biomarker in many diseases including endometrial carcinoma (EC). miR-486-5p dysregulation is observed in several tumor types, but the roles of miR-486-5p in EC are hardly ever studied. OBJECTIVE: This study aimed to analyze the expression profile of miR-486-5p in tumor tissues and serum samples of patients with EC and explore the target prediction, function analysis and validation in immortal cell lines. PATIENTS AND METHODS: A total of 42 freshly paired EC tissues, the corresponding adjacent non-neoplastic tissues and serum samples were also collected from patients with EC, and 42 matched normal serum samples were included as control group. The level of miR-486-5p expression was tested by quantitative real-time polymerase chain reaction (qRT-PCR). Cell proliferation was determined by colony formation assay and CCK-8 assay. Furthermore, functional evaluation of miR-486-5p on migration was performed by wound-healing assay and invasion was estimated by transwell invasion assay. qRT-PCR, luciferase reporter assay and Western blotting (WB) were performed to verify the targeting of MARK1 by miR-486-5p. RESULTS: miR-486-5p was significantly up-regulated in EC tissues and serum samples, promoting the proliferation, migration and invasive activities of EC cells by targeting MARK1. CONCLUSION: These data indicated miR-486-5p as a novel molecular biomarker for diagnosing and treating EC, and MARK1 might act as a critical and functional target of miR-486-5p with the implications on cell proliferation, migration and invasiveness of EC tumor cells.

16.
Proc Natl Acad Sci U S A ; 117(27): 15409-15413, 2020 Jul 07.
Article in English | MEDLINE | ID: mdl-32571928

ABSTRACT

The resistance of a conventional insulator diverges as temperature approaches zero. The peculiar low-temperature resistivity saturation in the 4f Kondo insulator (KI) SmB6 has spurred proposals of a correlation-driven topological Kondo insulator (TKI) with exotic ground states. However, the scarcity of model TKI material families leaves difficulties in disentangling key ingredients from irrelevant details. Here we use angle-resolved photoemission spectroscopy (ARPES) to study FeSb2, a correlated d-electron KI candidate that also exhibits a low-temperature resistivity saturation. On the (010) surface, we find a rich assemblage of metallic states with two-dimensional dispersion. Measurements of the bulk band structure reveal band renormalization, a large temperature-dependent band shift, and flat spectral features along certain high-symmetry directions, providing spectroscopic evidence for strong correlations. Our observations suggest that exotic insulating states resembling those in SmB6 and YbB12 may also exist in systems with d instead of f electrons.

17.
RSC Adv ; 10(40): 23702-23711, 2020 Jun 19.
Article in English | MEDLINE | ID: mdl-35517347

ABSTRACT

The present study executed iron pentacarbonyl pyrolysis to synthesize one-dimensional structured carbonyl iron fibers (CIFs) via carrier gas induced flow. The obtained CIFs with a diameter of 100-300 nm and length-diameter ratio of more than 20, are actually composed of a large number of nanocrystalline aggregates. We investigated the dependence of the structure, morphology, and static magnetic and electromagnetic properties of the CIFs on the pyrolysis temperatures. CIFs synthesized at 300 °C (denoted as CIF-300) exhibited optimal microwave absorption properties dependent on the fiber structure and well-matched impedance. An optimal reflection loss of -58.1 dB was observed at 13.8 GHz with a matching thickness of 1.43 mm. Furthermore, CIF-300 presented a broad effective absorption bandwidth (RL ≤ -10 dB) of 5.66 GHz with a thickness of 1.44 mm, indicating that it could be applied in practical applications from 3.74 GHz to 18.0 GHz by tuning its thickness from 1.0 mm to 4.0 mm. This paper not only reveals that the CIFs synthesized at 300 °C have great potential application in microwave absorbing materials (MAMs) with thin thicknesses, wide absorption bandwidths, and strong absorption intensities, but also provides a simple approach to prepare metal fibers.

18.
Science ; 366(6469): 1099-1102, 2019 11 29.
Article in English | MEDLINE | ID: mdl-31780552

ABSTRACT

In normal metals, macroscopic properties are understood using the concept of quasiparticles. In the cuprate high-temperature superconductors, the metallic state above the highest transition temperature is anomalous and is known as the "strange metal." We studied this state using angle-resolved photoemission spectroscopy. With increasing doping across a temperature-independent critical value p c ~ 0.19, we observed that near the Brillouin zone boundary, the strange metal, characterized by an incoherent spectral function, abruptly reconstructs into a more conventional metal with quasiparticles. Above the temperature of superconducting fluctuations, we found that the pseudogap also discontinuously collapses at the very same value of p c These observations suggest that the incoherent strange metal is a distinct state and a prerequisite for the pseudogap; such findings are incompatible with existing pseudogap quantum critical point scenarios.

19.
Rev Sci Instrum ; 90(6): 065105, 2019 Jun.
Article in English | MEDLINE | ID: mdl-31254998

ABSTRACT

The steam generator (SG) is a heat exchange device between a sodium coolant and water in sodium-cooled fast reactors. Its transfer tubes are prone to leakage to result in sodium-water reaction, which will affect the operational safety of the entire nuclear reactor. To this end, a signal processing method is studied to detect the SG leakage using an electromagnetic vortex flowmeter (EVFM). Water flow is firstly used to replace liquid sodium for conducting the hydraulic experiments, and the output signal of the sensor of the EVFM (abbreviated as EVFM sensor output signal) is collected under different gas injection volumes. The characteristics of the signal are analyzed in the time domain, and the collected signals are modeled. A signal processing method of bubble detection in liquid sodium is proposed based on the peak-to-peak standard deviation, which is realized in real time on the hardware system based on a digital signal processor. The gas injection experiments in liquid sodium are conducted to verify the effectiveness of the signal processing method and system developed in this paper. The minimum amount leakage of water can be detected as 0.1 g/s.

20.
Proc Natl Acad Sci U S A ; 116(9): 3449-3453, 2019 02 26.
Article in English | MEDLINE | ID: mdl-30808739

ABSTRACT

Fermi surface (FS) topology is a fundamental property of metals and superconductors. In electron-doped cuprate Nd2-x Ce x CuO4 (NCCO), an unexpected FS reconstruction has been observed in optimal- and overdoped regime (x = 0.15-0.17) by quantum oscillation measurements (QOM). This is all the more puzzling because neutron scattering suggests that the antiferromagnetic (AFM) long-range order, which is believed to reconstruct the FS, vanishes before x = 0.14. To reconcile the conflict, a widely discussed external magnetic-field-induced AFM long-range order in QOM explains the FS reconstruction as an extrinsic property. Here, we report angle-resolved photoemission (ARPES) evidence of FS reconstruction in optimal- and overdoped NCCO. The observed FSs are in quantitative agreement with QOM, suggesting an intrinsic FS reconstruction without field. This reconstructed FS, despite its importance as a basis to understand electron-doped cuprates, cannot be explained under the traditional scheme. Furthermore, the energy gap of the reconstruction decreases rapidly near x = 0.17 like an order parameter, echoing the quantum critical doping in transport. The totality of the data points to a mysterious order between x = 0.14 and 0.17, whose appearance favors the FS reconstruction and disappearance defines the quantum critical doping. A recent topological proposal provides an ansatz for its origin.

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