362 research outputs found
High-performance Self-lubricating Ceramic Composites with Laminated-graded Structure
High-performance ceramic composites are potential candidates for the application of wear-resistance components because of their excellent properties. Nevertheless, many problems, such as high friction coefficient of ceramic material and poor mechanical properties of ceramic-matrix self-lubricating composites, limit a wider range of applications of these composites in tribological areas. Therefore, improving high-toughness ceramic-matrix self-lubricating materials for practical applications is significant. This study proposes a new design for ceramic self-lubricating composites to overcome the conflict between their mechanical and tribological properties. Complying with the design principle of bionic and graded composites, two kinds of self-lubricating ceramic composites with laminated-graded structure were prepared, and their mechanical and tribological properties were studied. The results show that this newly developed ceramic composite has achieved satisfactory strength and tribological properties compared with the traditional ceramic self-lubricating composites. The bending strength reached the same level as the properties of general monolithic ceramics. In the temperature range of 25-800 °C, the friction coefficient of composites was less than 0.55, which was about half of that of monolithic ceramics
The linear and nonlinear inverse Compton scattering between microwaves and electrons in a resonant cavity
In a free space, the Sunyaev-Zel'dovich (SZ) effect is a small spectral
distortion of the cosmic microwave background (CMB) spectrum caused by inverse
Compton scattering of microwave background photons from energetic electrons in
the plasma. However, the microwave does not propagate with a plane waveform in
a resonant cavity, the inverse Compton scattering process is a little different
from that in a free space. By taking the Fourier expansion of the microwave
field in the cavity, the coefficients of the first-order and the higher-order
terms describe the local-space effect on the linear and nonlinear inverse
Compton scattering respectively. With our theoretical results, the linear or
nonlinear inverse Compton scattering cross section between microwave photons
and electrons has important applications on the energy calibration of the
extremely energetic electron beam, the sources of the terahertz waves, the
extreme ultra-violet (EUV) waves or the mid-infrared beams.Comment: 8 pages, 5 figure
Aerostructural Optimization of a Transonic Compressor Rotor
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/77121/1/AIAA-15397-760.pd
Aberrant Expression of N-Methylpurine-DNA Glycosylase Influences Patient Survival in Malignant Gliomas
Aim. To examine the expression of N-methylpurine-DNA glycosylase
(MPG) gene and protein in glioma samples with different WHO grades
and its association with patients' survival. Methods.
Immunohistochemistry assay, quantitative real-time PCR and Western
blot analysis were carried out to investigate the expression of
MPG gene and protein in 128 glioma and 10 non-neoplastic brain
tissues. Results. MPG gene expression level in glioma tissues was
significantly higher than that in non-neoplastic brain tissues
(P < 0.001). Immunohistochemistry also showed that MPG protein was
over-expressed in glioma tissues, which was consistent with the
resutls of Western blot analysis. Additionally, the expression
levels of MPG gene and protein both increase from grade I to grade
IV glioma according to the results of real-time PCR,
immunohistochemistry and western blot analysis. Moreover, the
survival rate of MPG-positive patients was significantly lower
than that of MPG-negative patients (P < 0.001). We further confirmed
that the over-expression of MPG was a significant and independent
prognostic indicator in glioma by multivariate analysis (P < 0.001).
Conclusions. Our data showed the over-expression of MPG gene and
protein in human gliomas, and also suggested for the first time
that MPG be an unfavorable independent prognostic indicator for
glioma patients
MicroRNA-223 Delivered by Platelet-Derived Microvesicles Promotes Lung Cancer Cell Invasion via Targeting Tumor Suppressor EPB41L3
Background: Patients with hematogenous metastatic lung cancer displayed significantly increased platelet count and aggregation compared to lung cancer patients without hematogenous metastasis. The mechanism underlying the correlation between the lung cancer hematogenous metastasis and platelet activation remains unknown. Results: In the present study, we explored the role of microRNA-223 (miR-223) derived from platelets in modulating lung cancer cell invasion. Our results demonstrated that platelets from NSCLC patients contain higher level of miR-223 than that from healthy subjects. The concentration of miR-223 in the platelet-secreted microvesicles (P-MVs) from NSCLC patients was also increased compared to that from healthy subjects. Incubation of human lung cancer A549 cells with P-MVs resulted in rapid delivery of miR-223 into A549 cells, in which platelet miR-223 targeted EPB41L3 and thus promoted A549 cell invasion. The effect of P-MVs on reducing EPB41L3 in A549 cells but promoting tumor cell invasion could be largely abolished by depletion of miR-223 via transfection with miR-223 antagomir. The role of EPB41L3 in inhibiting A549 cell invasion was further validated by directly downregulating EPB41L3 via transfecting cells with EPB41L3 siRNA or miR-223 mimic. Conclusions: Our study demonstrates for the first time that platelet-secreted miR-223 via P-MVs can promote lung cancer cell invasion via targeting tumor suppressor EPB41L3
Case Report: Primary hepatic neuroendocrine tumor: two cases report with literature review
Background & AimsPrimary hepatic neuroendocrine tumors (PHNETs) are rare malignant liver tumors that present diagnostic challenges owing to their rarity and absence of specific clinical features. This study aimed to investigate the characteristics of this rare liver tumor to enhance our understanding of the disease, improve diagnostic accuracy, and explore standardized diagnostic and treatment approaches.Case descriptionDuring physical examination, two elderly women, aged 64 and 74 years, were found to have liver masses. 18F-FDG Positron Emission Tomography-Computed Tomography (18F-FDG PET-CT) and Ga68-DOTATATE PET-CT scans of both individuals revealed multiple liver masses that were initially suspected to be hepatic neuroendocrine tumors. Subsequent puncture pathology confirmed the diagnosis of neuroendocrine tumors. Furthermore, in Case 1, the tumor was also detected by 18F-FDG PET-CT in the lung, suggesting a metastatic tumor, in conjunction with liver immunohistochemistry and imaging findings. Laboratory tests revealed no significant abnormalities in liver function or autoimmune liver disease indicators, and there was no evidence of viral hepatitis infection. However, partial hepatectomy was not indicated for cases with distant metastasis or multiple space-occupying lesions. Individualized treatment approaches have been developed for such situations. A large portion of the tumor underwent Transarterial Embolization (TAE), and targeted combination chemotherapy or endocrine therapy was administered based on the pathological results. During regular follow-ups a 13 and 12 months, the tumor remained stable. The patients’ quality of life was good, and their psychological well-being was healthy. They led active lifestyles, demonstrated a thorough understanding of their disease and its progression, and actively cooperated during the follow-up process.ConclusionOur findings suggest that a combination of serological, radiological, and immunohistochemical examinations can aid in the diagnosis of PHNET. In addition, we determined that TAE combined with drug therapy could be an effective method for controlling PHNET progression. Regular postoperative follow-ups are important for monitoring the prognosis and tumor progression status of patients with PHNET
Ultrafast Photoinduced Band Splitting and Carrier Dynamics in Chiral Tellurium Nanosheets
Trigonal tellurium (Te) is a chiral semiconductor that lacks both mirror and
inversion symmetries, resulting in complex band structures with Weyl crossings
and unique spin textures. Detailed time-resolved polarized reflectance
spectroscopy is used to investigate its band structure and carrier dynamics.
The polarized transient spectra reveal optical transitions between the
uppermost spin-split H4 and H5 and the degenerate H6 valence bands (VB) and the
lowest degenerate H6 conduction band (CB) as well as a higher energy transition
at the L-point. Surprisingly, the degeneracy of the H6 CB (a proposed Weyl
node) is lifted and the spin-split VB gap is reduced upon photoexcitation
before relaxing to equilibrium as the carriers decay. Using ab initio density
functional theory (DFT) calculations we conclude that the dynamic band
structure is caused by a photoinduced shear strain in the Te film that breaks
the screw symmetry of the crystal. The band-edge anisotropy is also reflected
in the hot carrier decay rate, which is a factor of two slower along c-axis
than perpendicular to it. The majority of photoexcited carriers near the
band-edge are seen to recombine within 30 ps while higher lying transitions
observed near 1.2 eV appear to have substantially longer lifetimes, potentially
due to contributions of intervalley processes in the recombination rate. These
new findings shed light on the strong correlation between photoinduced carriers
and electronic structure in anisotropic crystals, which opens a potential
pathway for designing novel Te-based devices that take advantage of the
topological structures as well as strong spin-related properties.Comment: 42 pages, 13 figure
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