Selective laser melting (SLM) is one kind of additive manufacturing process to fabricate metal parts through laser melting. A maraging steel 300 was manufactured by SLM. And the influence of process ...parameters (laser powder, scanning speed and scanning space) on the relative density of maraging steel 300 was investigated first. Then a series of block and plate specimens were manufactured. Some specimens were taken as control groups, and others underwent heat treatment by solution treatment (ST) and solution treatment +aging treatment (ST+AT) respectively. The investigation involved microstructure, microhardness, tensile strength and impact toughness. It is shown that: low or high laser power, scanning speed or scanning space all reduced the relative density, and the optimized process parameters could be obtained by orthogonal experiment. After ST, the cellular structure and microscopic segregation disappeared, and the new smaller particles precipitated out after AT. The Ni, Mo and Ti dissolved in the matrix during ST separated out again forming tiny Ni3Mo, Fe2Mo and Ni3Ti particles during AT. The microhardness and tensile strength dropped a little with elongation increasing after ST. While they increased significantly with elongation decreasing after AT. The impact toughness increased little after ST, but decreased sharply after AT.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Afterglow imaging that detects photons after cessation of optical excitation avoids tissue autofluorescence and thus possesses higher sensitivity than traditional fluorescence imaging. Purely organic ...molecules with room‐temperature phosphorescence (RTP) have emerged as a new library of benign afterglow agents. However, most RTP luminogens only emit visible light with shallow tissue penetration, constraining their in vivo applications. This study presents an organic RTP nanoprobe (mTPA‐N) with emission in the NIR range for in vivo afterglow imaging. Such a probe is composed of RTP molecule (mTPA) as the phosphorescent generator and an NIR‐fluorescent dye as the energy acceptor to enable room‐temperature phosphorescence resonance energy transfer (RT‐PRET), ultimately resulting in redshifted phosphorescent emission at 780 nm. Because of the elimination of background noise and redshifted afterglow luminescence in a biologically transparent window, mTPA‐N permits imaging of lymph nodes in living mice with a high signal‐to‐noise ratio. This study thus opens up a universal approach to develop organic RTP luminogens into NIR afterglow imaging agents via construction of RT‐PRET.
Phosphorescence resonance energy transfer is introduced to transfer the short‐wavelength emission of organic room‐temperature phosphorescence luminogens to near‐infrared fluorescent luminogens for realization of near‐infrared afterglow in vivo imaging. The doped nanoparticles of mTPA‐N are applied for subcutaneous and lymph‐node imaging in living mice with extremely low background noise and deep tissue penetration.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Bimetallic structures can combine the performance of dissimilar metal materials to meet the multifunctional requirement in industrial solutions. In this paper, steel-bronze bimetallic structures were ...fabricated via self-developed multi-material selective laser melting (SLM) equipment. In order to investigate the influence of laser power, scanning speed, and hatching space on the interfacial characterization, three factors and five levels of orthogonal experiments were performed on twenty layers of CuSn10 tin bronze after forming the 316 L stainless steel. Optical microscope (OM), large depth field microscope, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), tensile properties, electron backscattering diffraction (EBSD) and nanoindentation were used to characterize these bimetallic structures to validate the impact from process parameters. The large depth field microscope revealed protrusions at the steel/bronze interface, and its height increased and then decreased with increasing volumetric energy input. Besides, the generation of interfacial defects is related to the interfacial process parameters, and it is found that the types of defects are mainly classified as holes and cracks. Insufficient energy will cause cracks in the horizontal direction and then lead to bonding failure. Conversely, higher energy input will generate microcracks in the vertical direction. The defects near the interfacial region are the main factors affecting the ultimate strength of the bonding strength. As a result, the steel-bronze bimetallic structure displays optimal joint ultimate strength of 459.54 ± 3.08 MPa with elongation of 5.23 ± 0.65%, and minimum joint ultimate strength of 199.02 ± 0.56 MPa with elongation of 1.70 ± 0.22%. Their fracture morphology also exhibited gully-like and fan-shaped features, respectively. Additionally, the EBSD results show that there are fine grain regions appeared in the interfacial region, which helps increase the average nano-hardness of the interfacial region. This study provides a reference for the influence of process parameters on the interfacial characterization and mechanical properties of steel-bronze bimetallic parts prepared by selective laser melting.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
This article presents a method for manufacturing CuSn/18Ni300 bimetallic porous structure, and it mainly aims to discover microstructure and mechanical properties of CuSn/18Ni300 bimetallic porous ...structure. The microstructure, bonding strength and fracture morphology of CuSn/18Ni300 bimetallic parts manufactured by selective laser melting were examined by X-ray diffraction, tensile test and scanning electron microscopy, respectively. Compression behavior and energy absorption behavior were investigated by compression tests. Analyses of microstructure show that CuSn/18Ni300 specimen consists of α-Fe phase, α-Fe/α-Cu mixed area and α-Cu phase. Microhardness at the interface of CuSn/18Ni300 bimetallic porous structure decreases from 18Ni300 part to CuSn part. The bonding strength of CuSn/18Ni300 specimen is 144.1 ± 41.59 MPa, which is much lower than the tensile strength of CuSn specimen. Additionally, we demonstrate that the compression behavior of CuSn/18Ni300 bimetallic porous structure can be subdivided into five stages, including the first linear elasticity, the first collapse plateau, the second linear elasticity, the second collapse plateau and the end densification. The energy absorption of CuSn/18Ni300 porous structure is higher than that of CuSn porous structure, and energy absorption increases as the porosity decreases. These findings provide a solution for optimizing the compression behavior and energy absorption of porous structure.
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•Designed and manufactured body-center-cubic CuSn/18Ni300 bimetallic porous structures.•Studied on the microstructure and bonding strength of CuSn/18Ni300 bimetallic specimens.•Compression behaviors of CuSn/18Ni300 bimetallic porous structures can be subdivided into five stages.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Due to the rapid melting and solidification mechanisms involved in selective laser melting (SLM), CoCrMo alloys fabricated by SLM differ from the cast form of the same alloy. In this study, the ...surface morphologies, enhancement of mechanical properties and change to microstructure by heat treatment were discussed. Results showed that the microstructure of sample fabricated by SLM consisted mainly of face-centered-cubic (FCC) cobalt-rich solid solutions and carbide scattered cobalt-rich solid solutions, where Cr and Mo were dissolved in the Co-base phase and M23C6. The carbide scattered Co-base phase existed in the form of even margins. The tensile fracture of SLM-fabricated parts was mostly quasi-cleavage brittle fracture. Heat treatment transformed the SLM-fabricated parts such that failure occurred through ductile rather than brittle fracture, causing an increase in the tensile strength and elongation of the SLM-fabricated parts in addition to reduced yield strength and hardness. Some annealing twins were formed after heat treatment, which were demonstrated by TEM. These results will contribute to the development of biomedical CoCrMo alloys fabricated by SLM.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Tumorous vasculature plays key roles in sustaining tumor growth. Vascular disruption is accompanied by internal coagulation along with platelet recruitment and the resulting suppression of oxygen ...supply. We intend to artificially create this physiological process to establish the mutual feedback between vascular disruption and platelet-mimicking biotaxis for the cascade amplification of hypoxia-dependent therapy. To prove this concept, mesoporous silica nanoparticles are co-loaded with a hypoxia-activated prodrug (HAP) and a vessel-disruptive agent and then coated with platelet membranes. Upon entering into tumors, our nanotherapeutic can disrupt local vasculature for tumor inhibition. This platelet membrane-coated nanoplatform shares the hemorrhage-tropic function with parental platelets and can be persistently recruited by the vasculature-disrupted tumors. In this way, the intratumoral vascular disruption and tumor targeting are biologically interdependent and mutually reinforced. Relying on this mutual feedback, tumorous hypoxia was largely promoted by more than 20-fold, accounting for the effective recovery of the HAP’s cytotoxicity. Consequently, our bioinspired nanodesign has demonstrated highly specific and effective antitumor potency via the biologically driven cooperation among intratumoral vascular disruption, platelet-mimicking biotaxis, cascade hypoxia amplification, and hypoxia-sensitive chemotherapy. This study offers a paradigm of correlating the therapeutic design with the physiologically occurring events to achieve better therapy performance.
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IJS, KILJ, NUK, PNG, UL, UM
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•A design method of nonlinear periodically gradient porous structure is proposed.•The compression failure mechanism of the nonlinear porous structure was analyzed by digital image ...correlation technology and finite element analysis, and a periodic failure deformation was observed.•The strain-stress plateau length and effective energy absorption were improved by increasing the number of porosity cycles.
This research presents a design method of the nonlinear periodic gradient triply periodic minimal surface structures (NL-TPMS). The gradient porosity of NL-TPMS was controlled by a sinusoidal function and the influence of the number of cycles on the compression failure mechanism has been investigated. Homogenous TPMS and NL-TPMS were manufactured by laser powder bed fusion (LPBF) with 316L stainless steel powder. Digital image correlation (DIC) and finite element analysis (FEA) were applied to explore the compression behavior of NL-TPMS. The strain of the plateau end of homogenous TPMS decreases as the porosity increases, and the DIC results show that homogenous TPMS deformed with a 45° diagonal shear band. The compression results show that anisotropy of mechanical properties exists in NL-TPMS. The length of the first plateau and compressive proof strength increase as the number of cycles of porosity increases. The cycle of gradient porosity also influences the compression behavior of NL-TPMS, and a periodic failure deformation was observed in the NL-TPMS rather than a layer-by-layer compression deformation in normal gradient porous structures. The maximum principal strain of NL-TPMS detected by DIC presents a periodic distribution, which corresponds to the sinusoidal period designed function of NL-TPMS.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The cancer cell membrane contains an arsenal of highly specific homotypic moieties that can be used to recognize its own kind. These cell membranes are often used to coat spherical nanoparticles to ...enhance nanomedicines’ targeting specificities and uptakes. A sphere, however, has only a point contact with a surface at any given time. It is shown here that, by retaining a flatter morphology of the cracked cell membrane through stiffening with in situ synthesized gold nanomaterials, an increased area of interaction could be maintained and hence improve upon the in vitro and in vivo homotypic targeting capabilities between cancer cell types. This enhancement is especially important in vivo as any nanomedicine with targeting moieties probably has a single pass at interacting with the target cell before subsequent system clearance. Possible future clinical applications may involve the usage of a patient’s autologous tumor biopsy tissues, which are very limited in supply, and therefore ensuring that we capitalize on the entire collective surface area of the cancer cell membrane available becomes an important consideration in the design and delivery our cell membrane-derived nanomedicines.
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IJS, KILJ, NUK, PNG, UL, UM
Traumatic brain injury (TBI) is a central nervous system disease caused by external trauma, which has complex pathological and physiological mechanisms. The aim of this study was to explore the ...correlation between immune cell infiltration and ferroptosis post-TBI.
This study utilized the GEO database to download TBI data and performed differentially expressed genes (DEGs) and ferroptosis-related differentially expressed genes (FRDEGs) analysis. DEGs were further analyzed for enrichment using the DAVID 6.8. Immunoinfiltration cell analysis was performed using the ssGSEA package and the Timer2.0 tool. The WGCNA analysis was then used to explore the gene modules in the data set associated with differential expression of immune cell infiltration and to identify the hub genes. The tidyverse package and corrplot package were used to calculate the correlations between hub genes and immune cell infiltration and ferroptosis-marker genes. The miRDB and TargetScan databases were used to predict complementary miRNAs for the Hub genes selected from the WGCNA analysis, and the DIANA-LncBasev3 tool was used to identify target lncRNAs for the miRNAs, constructing an mRNA-miRNA-lncRNA regulatory network.
A total of 320 DEGs and 21 FRDEGs were identified in GSE128543. GO and KEGG analyses showed that the DEGs after TBI were primarily associated with inflammation and immune response. Xcell and ssGSEA immune infiltration cell analysis showed significant infiltration of T cell CD4
central memory, T cell CD4
Th2, B cell memory, B cell naive, monocyte, macrophage, and myeloid dendritic cell activated. The WGCNA analysis identified two modules associated with differentially expressed immune cells and identified Lgmn as a hub gene associated with immune infiltrating cells. Lgmn showed significant correlation with immune cells and ferroptosis-marker genes, including Gpx4, Hspb1, Nfe2l2, Ptgs2, Fth1, and Tfrc. Finally, an mRNA-miRNA-lncRNA regulatory network was constructed using Lgmn.
Our results indicate that there is a certain correlation between ferroptosis and immune infiltrating cells in brain tissue after TBI, and that Lgmn plays an important role in this process.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
SiC ceramics with high thickness and high density are highly advantageous for armor protection, but it is difficult to produce bulk SiC ceramics with thicknesses more than 100 mm. This work was ...concentrated on the problems of easy cracking and non-densification in the thick SiC ceramic sintering, and degreasing products as well as pressure-incomplete degreasing process were investigated. In order to degrease thick ceramics, phenolic resin's pyrolysis residue was examined using TG-MS. Formaldehyde and other small-molecule byproducts of breakdown were quickly eliminated, but macromolecule byproducts like dimethylphenol were easily retained in the core,leading to the noncompact sintering of thick ceramics. After degreasing optimization, the blank's surface-core density is almost constant, ranging from 1.81 to 1.84 g/cm~3. In contrast, the test group shows no cracking or deformation after sintering at 2150 ℃, and both surface and core of the large thickness ceramics obtain a density up to 3.14 g/cm~3 with similar
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