MAX phase solid solutions obtained by alloying at M-, A- and X-sites have attracted much attention recently to adjust the lattices and control the properties of MAX phases. In this work, a series of ...porous Ti3(Al,Si)C2 solid solutions were fabricated by pressureless sintering with Ti/Al/Si/TiC powder mixtures. Pore structures and effects of Si content were systematically characterized. The Si substitution affected the pore structure of porous Ti3(Al,Si)C2 following a V-shaped law: when xSi≤0.4, the porosity decreased together with the reduced pore size, narrow distribution and increased tortuosity factor; when xSi>0.4, the porosity and pore size increased together with the decreased tortuosity factor. Considering the specific application as capillary wick materials, the capillary performance, compressive strength and thermal conductivity of porous Ti3(Al,Si)C2 solid solution were further measured. The results showed that the larger porosity improved the capillary performance, but decreased the compressive strength and thermal conductivity. Compared with porous Ti3AlC2 of similar porosity, porous Ti3Al0.4Si0.6C2 had smaller pore size with more concentrated distribution, but better overall performances (the much better capillary performance, higher compressive strength and lower thermal conductivity). It was demonstrated that the adapt Si substitution achieved the overall promotions of porous Ti3AlC2, and porous Ti3Al0.4Si0.6C2 solid solution could act as the novel wick materials and show broad prospects in loop heat pipes (LHPs).
Herein, the influence of Ti additive on the formation of intermetallic compounds (IMC) in a SAC/Cu-Ti soldered joint and corresponding mechanical properties are systematically investigated. The ...Ti-to-Cu ratio under bump metallization (UBM) is adjusted by tuning the target current during magnetron sputtering. Interestingly, the needle-like IMC, which is different from the traditional scallop-like IMC, is formed in the SAC/Cu-Ti soldered joint after reflow. The growth of Cu
3
Sn and Kirkendall voids is significantly inhibited after thermal aging in the SAC/Cu-Ti soldered joint. Overall, the segregation of Ti at grain boundaries forms a titanium-rich layer. Also, the Ti-rich layer acts as a diffusion barrier layer and hinders the diffusion of Cu into IMC. The shear strength test results show that SAC/Cu-Ti has much stronger strength than SAC/Cu both before and after thermal aging. These results confirm that Cu-Ti UBM is beneficial to the improvement of welding reliability.
Neuroinflammation is one of the most important pathological processes following brain ischemia. Pulsed electromagnetic fields (PEMFs) protect against brain ischemia, but their role in regulating ...neuroinflammation remains unclear. In the present study, we investigated the biological effects of PEMF exposure on brain ischemia-induced neuroinflammation through the astrocytic cholinergic anti-inflammatory pathway. PEMF exposure reduced the activation of astrocytes and neuroinflammation following brain ischemia by directly modulating astrocytic injury and inflammatory cytokine release. Inhibition of nicotinic acetylcholine receptor alpha 7 subunit (α7nAChR) by a specific antagonist reversed the regulatory effects of PEMF on astrocytes. Furthermore, negative regulation of signal transducer and activator of transcription 3 (STAT3) by α7nAChR was found to be an important downstream mechanism through which PEMF regulates astrocyte-related neuroinflammation. PEMF suppressed STAT3 phosphorylation and nuclear translocation by activating α7nAChR. These results demonstrate that PEMF exerts anti-inflammatory effects in the context of brain ischemia by modulating astrocytic α7nAChR/STAT3 signaling.
Graphical Abstract
The Gd-Fe-Al amorphous/nanocrystalline composites were successfully designed and obtained with both high Curie temperature (Tc) and large magnetic entropy change (ΔSM). The Tc can be tuned from 172 ...to 280 K and refrigeration capacity (RC) has a value between 690 and 867 J/kg under a field change of 0–5 T by changing the Gd contents and the formation of Gd nanocrystallites. And, ΔSM in Gd-Fe-Al amorphous/nanocrystalline composites reached a value of 7.2 J kg−1 K−1 under a field change of 0–5 T. The high RC in Gd-Fe-Al system were ascribed to the widening full width at half maximum (δFWHM) up to 240 K of the magnetic entropy change (ΔSM
max) peak because of the combination contribution of amorphous matrix and the precipitated Gd-riched nanocrystalline. Our research would shed light on how to design attractive candidates for magnetic refrigeration materials with high performance at near room temperature.
Herein, the Cu target is prepared by combining different pieces, with a large variation in grain size, and installed in a UDP-650 closed-field unbalanced ion coating machine for sputtering ...experiments. The influence of grain size on surface morphology and sputtering performance of Cu targets is studied under the same process conditions. In the constant current mode, the sputtering voltage of target continues to decrease during the target lifetime, which is consistent with the increase of magnetic field intensity on the target surface due to the decrease of target thickness. During the first 7.5 h of sputtering erosion, the sputtering yield of Cu target slightly increases with sputtering time, followed by a gradual decrease. The results reveal that the grain size renders a significant effect on surface morphology of the Cu target after sputtering. The Cu target with small grain size renders high particle density in the edge area of sputter erosion groove, however, the particle-like morphology size is not influenced by the grain size. In the deepest region of sputtering erosion, the Cu target with two distinct grain sizes presents a flat morphology and the smaller grain size results in more flat morphology. At each stage of the life cycle of target material, the Cu target sputtering voltage initially decreases and, then, gradually becomes stable, while the cavity pressure initially increases and gradually becomes stable. The sputtering yield of the samples, with the grain size of 10–20 μm, is found to be greater than the samples with the grain size of 120–150 μm during each stage. Therefore, the Cu target with a small grain size should be selected to ensure the desired film deposition rate and stability of the sputtering process.
Glioma is the most common primary tumor of the central nervous system with a high lethality rate. This study aims to mine fibroblast-related genes with prognostic value and construct a corresponding ...prognostic model.
A glioma-related TCGA (The Cancer Genome Atlas) cohort and a CGGA (Chinese Glioma Genome Atlas) cohort were incorporated into this study. Variance expression profiling was executed via the "limma" R package. The "clusterProfiler" R package was applied to perform a GO (Gene Ontology) analysis. The Kaplan-Meier (K-M) curve, LASSO regression analysis, and Cox analyses were implemented to determine the prognostic genes. A fibroblast-related risk model was created and affirmed by independent cohorts. We derived enriched pathways between the fibroblast-related high- and low-risk subgroups using gene set variation analysis (GSEA). The immune infiltration cell and the stromal cell were calculated using the microenvironment cell populations-counter (MCP-counter) method, and the immunotherapy response was assessed with the SubMap algorithm. The chemotherapy sensitivity was estimated using the "pRRophetic" R package.
A total of 93 differentially expressed fibroblast-related genes (DEFRGs) were uncovered in glioma. Seven prognostic genes were filtered out to create a fibroblast-related gene signature in the TCGA-glioma cohort training set. We then affirmed the fibroblast-related risk model via TCGA-glioma cohort and CGGA-glioma cohort testing sets. The Cox regression analysis proved that the fibroblast-related risk score was an independent prognostic predictor in prediction of the overall survival of glioma patients. The fibroblast-related gene signature revealed by the GSEA was applicable to the immune-relevant pathways. The MCP-counter algorithm results pointed to significant distinctions in the tumor microenvironment between fibroblast-related high- and low-risk subgroups. The SubMap analysis proved that the fibroblast-related risk score could predict the clinical sensitivity of immunotherapy. The chemotherapy sensitivity analysis indicated that low-risk patients were more sensitive to multiple chemotherapeutic drugs.
Our study identified prognostic fibroblast-related genes and generated a novel risk signature that could evaluate the prognosis of glioma and offer a theoretical basis for clinical glioma therapy.
Glutamate receptor (GluR)-mediated excitotoxicity is an important mechanism causing delayed neuronal injury after traumatic brain injury (TBI). Preso, as a core scaffolding protein of postsynaptic ...density (PSD), is considered an important regulator during excitotoxicity and TBI and combines with glutamate receptors to form functional units for excitatory glutamatergic neurotransmission, and elucidating the mechanisms of these functional units will provide new targets for the treatment of TBI. As a multidomain scaffolding protein, Preso directly interacts with metabotropic GluR (mGluR) and another scaffold protein, Homer. Because the mGluR-Homer complex plays a crucial role in TBI, modulation of this complex by Preso may be an important mechanism affecting the excitotoxic damage to neurons after TBI. Here, we demonstrate that Preso facilitates the interaction between metabotropic mGluR1 and Homer1 to activate mGluR1 signaling and cause excitotoxic neuronal injury and endoplasmic reticulum (ER) stress after TBI. The regulatory effect of Preso on the mGluR1-Homer1 complex is dependent on the direct association between Preso and this complex and also involves the phosphorylation of the interactive binding sites of mGluR1 and Homer1 by Preso. Further studies confirmed that Preso, as an adaptor of cyclin-dependent kinase 5 (CDK5), promotes the phosphorylation of the Homer1-binding site on mGluR1 by CDK5 and thereby enhances the interaction between mGluR1 and Homer1. Preso can also promote the formation of the mGluR1-Homer1 complex by inhibiting the phosphorylation of the Homer1 hinge region by Ca
/calmodulin-dependent protein kinase IIα (CaMKIIα). Based on these molecular mechanisms, we designed several blocking peptides targeting the interaction between Preso and the mGluR1-Homer1 complex and found that directly disrupting the association between mGluR1 and scaffolding proteins significantly promotes the recovery of motor function after TBI.
Multilayer hard coatings of TiCN/TiC/TiN on high speed steel substrates were deposited using a chemical vapor deposition system. Evaluations of microstructure, wear morphology of coatings were ...characterized by scanning electron microscopy, and optical microscopy. Friction coefficient and wear rates of coatings were investigated using ball-on-disk tester sliding against a WC ball at a constant load of 20
N. Tribological behavior of the coatings at room and elevated temperature were discussed. Different changing tendency of friction coefficient were observed from ball-on-disc experiments. Results showed that the friction coefficient of coatings increased gradually to a highest value, then to a relatively constant value at room temperature dry sliding wear. The friction coefficient exhibited a reverse variation tendency at temperature of 550
°C. It got a higher value at the first sliding friction cycles. Then the value of friction coefficient decreased, suffered irregular oscillations and kept a relatively lower value with increasing sliding time. Reasons of the variation of friction coefficient with sliding time and wear mechanism were analyzed and discussed at room and elevated temperatures, respectively.
► A novelty ZrNbAlNx multilayer film with different N2 flow rate was deposited. ► Chemical composition and property of multilayer films were affected by N2 flow rate. ► Vickers hardness value shows a ...typical variation with the increase in N2 flow rate.
Deposition property and microstructure evolution of nano-scaled ZrNbAlNx multilayer films, which present a periodic modulation structure of ZrNx/AlNx/ZrNx/NbNx with different N atomic concentration, deposited using a reactive unbalanced magnetron sputtering system was investigated by varying N2 flow rate. Multilayer films were characterized using X-ray diffraction, Scanning electron microscope, Transmission electron microscope, Laser Raman spectrometer and nano-indentation tester. The experimental results show that the nano-scaled multilayer film displays a columnar growth at N2 flow rate of 4sccm and an un-columnar deposition at N2 flow rate of 33sccm. The increase in N2 flow rate leads to increase of N atomic concentration and decrease of Zr atomic concentration. Microstructure of multilayer films indicates a variation from close-packed hexagonal structure with (101) preferred orientation to faced cubic structure with (111) preferred orientation. The Raman spectrums position presents a shift corresponding to microstructure evolution of multilayer films. Maximum micro-hardness value of multilayer film is 22GPa at N2 flow rate of 27.5sccm.
This study developed a novel and inexpensive method for fabricating size-tunable tapered antireflective nanopillars on a polycarbonate (PC) film using hybrid nano-patterning lithography consisting of ...nanosphere lithography (NSL) and nanoimprint lithography (NIL). The optical properties of the antireflective surfaces can be controlled by the CrN nanomold morphologies resulting from the different reactive ion etching conditions. The nanomold surface of CrN nanohole arrays has a low surface energy at the interface and has an anti-sticking property that can be applied in the problem of the sticking during demolding. A high-performance antireflective tapered nanopillar layer was successfully imprinted on a PC film surface using a contactless gas assisted pressing process along with a CrN nanomold prepared by NSL. The optical properties of antireflective characteristic of the PC tapered nanostructures were analyzed. Such antireflective surfaces are promising for fabrication of high light transmittance and antireflective optical materials to be used in many important fields.
•This study presents a high-throughput strategy and low-cost.•The size-tunable tapered antireflective nanopillars can be controlled by hybrid nano-patterning lithography.•The transmittance of the PC tapered antireflective nanopillars was enhanced in the visible wavelength.
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