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Laser metal deposition (LMD) provides a unique approach for surface modification and additive manufacturing. It typically leads to the formation of columnar crystal structures and defects in metals. In this study, ultrasonic vibration was applied on LMD of 316L. Contrastive studies show that columnar microstructures were observed without ultrasound, while equiaxed crystal structures were found with ultrasonic vibration. The reasons to generate the equiaxed microstructures were discussed. The results provide a feasible method for improving the quality of additive manufactured parts.

SUMMARYT cell function is defined by both T cell receptors (TCR) and T cell gene expression (GEX). Although single-cell technology enables the simultaneous capture of TCR and GEX information, the lack of a reference atlas and computational tools hinders our ability to uncover the fundamental TCR usage rules and to efficiently characterize disease-associated TCRs (dTCR). Here, through the collection of million-scale single-cell GEX-TCR reference atlas comprising 20 diverse disease conditions, we revealed the intrinsic features of TCR-MHC (Major Histocompatibility Complex) restriction in CD4/CD8 lineages. We observed the higher coherence for TCRα/β chains in memory T cells, and detected widely-existing public TCRα/β pairs across individuals. Building upon the reference atlas, we introduced TCR- DeepInsight, a deep-learning framework featuring a disease specificity scoring system that enables the characterization of dTCR clusters with similar GEX-TCR. Our study provides a valuable tool for researchers to analyze single-cell GEX-TCR data and identify dTCRs comprehensively and robustly.

Many medical image datasets have been collected without proper annotations for deep learning training. In this paper, we propose a novel unsupervised domain adaptation framework with adversarial learning to minimize the annotation efforts. Our framework employs a task specific network, i.e., fully convolutional network (FCN), for spatial density prediction. Moreover, we employ a domain discriminator, in which adversarial learning is adopted to align the less-annotated target domain features with the well-annotated source domain features in the feature space. We further propose a novel training strategy for the adversarial learning by coupling data from source and target domains and alternating the subnet updates. We employ the public CBIS-DDSM dataset as the source domain, and perform two sets of experiments on two target domains (i.e., the public INbreast dataset and a self-collected dataset), respectively. Experimental results suggest consistent and comparable performance improvement over the state-of-the-art methods. Our proposed training strategy is also proved to converge much faster.

Rationale and Objectives To assess whether a fully-automated deep learning system can accurately detect and analyze truncal musculature at multiple lumbar vertebral levels and muscle groupings on abdominal CT for potential use in the detection of central sarcopenia. Materials and Methods A computer system for automated segmentation of truncal musculature groups was designed and created. Abdominal CT scans of 102 sequential patients (mean age 68 years, range 59–81 years; 53 women, 49 men) conducted between January 2015 and February 2015 were assembled as a data set. Truncal musculature was manually segmented on axial CT images at multiple lumbar vertebral levels as reference standard data, divided into training and testing subsets, and analyzed by the system. Dice similarity coefficients were calculated to evaluate system performance. IRB approval was obtained, with waiver of informed consent in this retrospective study. Results System performance as gauged by the Dice coefficients, for detecting the total abdominal muscle cross-section at the level of the third and fourth lumbar vertebrae, were, respectively, 0.953 ± 0.015 and 0.953 ± 0.011 for the training set, and 0.938 ± 0.028 and 0.940 ± 0.026 for the testing set. Dice coefficients for detecting total psoas muscle cross-section at the level of the third and fourth lumbar vertebrae, were, respectively, 0.942 ± 0.040 and 0.951 ± 0.037 for the training set, and 0.939 ± 0.028 and 0.946 ± 0.032 for the testing set. Conclusion This system fully-automatically and accurately segments multiple muscle groups at all lumbar spine levels on abdominal CT for detection of sarcopenia.

Electroless plating of Ni on the surfaces of multi-walled carbon nanotubes (MWCNTs) with two types of thicknesses were achieved. The structural evolution of MWCNTs in the laser cladding processing was investigated. It is observed that the MWCNTs can partially survive in the laser additive layers, but most of the tubes are unzipped, forming the graphene nano sheets (GNSs) and fragments. It is also found that the graphene fragments are inter-bonded with the neighboring ones, resulting in the formation of large porous carbon nano ribbons (CNRs). Due to the high surface area of the GNSs and CNRs, the element segregation and Laves phase formation in the laser cladded IN718 superalloy are suppressed significantly. With the thickness-increase of the Ni layer, the perfection of the graphene structure in the GNSs and CNRs is enhanced, and correspondingly, the depression effect on the element segregation and Laves phase formation of IN718 superalloy is improved.

It is report here a new family of organic-inorganic bismuth halides bearing a formula of A2BiX5, in which A is monovalent long-chain alkylammonium and X is halide. Two compounds, (BA)2BiBr5 (BA: C4H9NH3+) and (OA)2BiBr5 (OA: C8H17NH3+), have been synthesized and investigated by single crystal and powder X-ray diffractions, UV–vis absorption and fluorescence spectroscopies, and density functional theoretical calculations. An orthorhombic crystalline structure with a P212121 space group, which had not been reported for organobismuth halides before, was found existing in (OA)2BiBr5 single crystals. Besides bulk materials, the quantum dots (QDs) of (BA)2BiBr5 and (OA)2BiBr5 were prepared and demonstrated as blue emitters with photoluminescent quantum yields of 1.26% and 0.50%, respectively, after capping with oleic acid. Finally, mixed halides with various I/Br ratios were prepared and found to form certain solid solutions with homogeneous distributed I− and Br−. Upon tuning I/Br ratio, the absorption and emission bands of their QDs can be easily modulated.

OBJECTIVE: Calcification of the coronary arteries, aorta, and branch vessels can occur in both large-vessel vasculitis (LVV) and atherosclerosis. The study objective was to determine the location and amount of vascular calcification in patients with LVV versus hyperlipidemia (HLD) and to identify risk factors associated with vascular calcification in LVV. METHODS: Patients with giant cell arteritis (GCA), Takayasu’s arteritis (TAK), and HLD underwent non-contrast computed tomography of the aorta and branch vessels. Vascular calcification in 14 specific arterial territories (4 segments of the aorta, 9 branch arteries, and the coronary arteries) was quantified throughout the large arteries by a cumulative Agatston score. Multivariate linear regression analyses were used to identify associations between traditional and disease-specific risk factors and total Agatston score. RESULTS: A total of 88 subjects, including GCA (n=29); TAK (n=22); and HLD (n=37), participated.Prevalence of vascular calcification in the aorta and branch vessels significantly differed in the coronary arteries (HLD=67%, GCA=35%, TAK=9%, p

Titanium alloy produced by selective laser melting (SLM) requires surface treatment to improve its bioactivity. In this study, Micro-arc oxidation (MAO) was applied on TC4 alloy produced by SLM with a homogeneous coating of microporous TiO2 and significant amounts of Ca and P. The microstructure, thickness, roughness, and composition of the MAO coating with different oxidation times were characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM), energy-dispersive spectroscopy (EDS), and X-ray diffraction (XRD), respectively. The adhesion strength of the MAO coating was obtained by scratch testing. The corrosion behavior of the MAO coatings was evaluated by potentiodynamic polarization test and electrochemical impedance spectroscopy. The bioactivity of the coatings was carried out by immersion test in simulated body fluid (SBF). The results showed that the thickness of the MAO coatings, roughness and pore size gradually increase as a function of the oxidation time, which at the same time increases the rutile phase constituent. The coating prepared by 15 min exhibited the best adhesive strength, which mainly consists of TiO2, CaO, CaHPO4 and Ca3(PO4)2. The corrosion resistance and bioactivity of MAO coatings could be improved by changing the oxidation time, and MAO coating formed at 15 min has the best corrosion resistance and bioactivity. The whole MAO process on SLM-produced TC4 alloy can be divided into four stages through “anodic oxidation → film puncturing → micro-arc oxidation → arc light stage” according to voltage change and microstructure evolution. In addition, a large amount of grain boundary interfacial area in SLM-produced TC4 alloy may participate in the MAO reaction to form a large number of discharge channels and share the total energy to decline energy density.

BACKGROUND: In lymphangioleiomyomatosis (LAM), infiltration of the lungs with smooth muscle-like LAM cells results in cystic destruction and decline in lung function, effects stabilized by sirolimus therapy. LAM lung disease is followed, in part, by high-resolution CT scans. To obtain further information from these scans, we quantified changes in lung parenchyma by analyzing image “texture.” METHODS: Twenty-six texture properties were quantified by analyzing the distribution and intensity of pixels with a computer-aided system. Both cross-sectional and longitudinal studies were performed to examine the relationships between texture properties, cyst score (percentage of lung occupied by cysts), FEV(1), and diffusion capacity for carbon monoxide (Dlco), and to determine the effect of sirolimus treatment. RESULTS: In the cross-sectional study, 18 texture properties showed significant positive correlations with cyst score. Cyst score and 13 of the 18 texture properties showed significant differences in rates of change after sirolimus treatment; 11 also significantly predicted FEV(1) and Dlco. CONCLUSIONS: Increased cyst score was associated with increased texture degradation near cysts. Sirolimus treatment improved lung texture surrounding cysts and stabilized cyst score. Eleven texture properties were associated with FEV(1), Dlco, cyst score, and response to sirolimus. Texture analysis may be valuable in evaluating LAM severity and treatment response.

Background Given the rising utilization of medical imaging and the risks of radiation, there is increased interest in reducing radiation exposure. The objective of this study was to evaluate, as a proof of principle, CT scans performed at radiation doses equivalent to that of a posteroanterior and lateral chest radiograph series in the cystic lung disease lymphangioleiomyomatosis (LAM). Methods From November 2016 to May 2018, 105 consecutive subjects with LAM received chest CT scans at standard and ultra-low radiation doses. Standard and ultra-low-dose images, respectively, were reconstructed with routine iterative and newer model-based iterative reconstruction. LAM severity can be quantified as cyst score (percentage of lung occupied by cysts), an ideal benchmark for validating CT scans performed at a reduced dose compared with a standard dose. Cyst scores were quantified using semi-automated software and evaluated by linear correlation and Bland-Altman analysis. Results Overall, ultra-low-dose CT scans represented a 96% dose reduction, with a median dose equivalent to 1 vs 22 posteroanterior and lateral chest radiograph series (0.14 mSv; 5th-95th percentile, 0.10-0.20 vs standard dose 3.4 mSv; 5th-95th percentile, 1.5-7.4; P Conclusions In LAM chest CT scan at substantial radiation reduction to doses equivalent to that of a posteroanterior and lateral chest radiograph series provides cyst score quantification similar to that of standard-dose CT scan. Trial Registry ClinicalTrials.gov; Nos.: NCT00001465 and NCT00001532 ; URL: www.clinicaltrials.gov .

The expression status of HER2 is an important factor in evaluating the prognosis of breast cancer. We found that the positivity rate of HER2 varied with the diameter of invasive lesions in early breast cancer.We aimed to explore the relationship between the change of HER2 positivity rate of early breast cancer and the diameter of the invasive foci and its clinical significance.A total of 217 patients with microinvasive breast cancer and T1a stage breast cancer were enrolled in this study. Machine learning algorithm was used to extract morphological features of invasive lesions in early breast cancer. Using Spearman to analysis the clinicopathological and morphological features related to HER2 expression McNemar test was used to analyze the consistency of HER2 expression between the carcinoma in situ area and the invasive cancer area.In early breast cancer, the diameter of the invasive foci was strongly negatively correlated with the expression status of HER2 (rho=-0.468, p 0.001). As the diameter of the invasive foci increases, the HER2 positivity rate gradually decreases. When the diameter of the invasive foci 2 mm, the positivity rate of HER2 was significantly reduced (from 52.6% to 16.1%, p 0.001), which was close to the positivity rate of HER2 in ordinary invasive breast cancer. Moreover, most of the clinicopathological characteristics of breast cancer with an invasive lesion diameter of 1-2 mm and DCIS-MI were not significantly different (p 0.05). Among 217 patients, the consistency rate of HER2 expression in carcinoma in situ and invasive foci areas was 97.7% (212/217), and there was no significant difference in HER2 expression status (p = 0.25 and p = 0.50, respectively).We recommend that breast cancer with an invasive lesion diameter of 1-2 mm should be classified as microinvasive breast cancer. In early breast cancer,the expression status of HER2 in the invasive foci area can refer to the HER2 expression status in carcinoma in situ area. However, it needs further support from a large amount of data and follow-up results.

Herein, we demonstrate the successful preparation of a novel complex transition metal oxide (TiVO3.5) by oxidizing a solid-solution MXene (Ti0.5V0.5)3C2 at 300 °C and its high activity as a catalyst precursor in the hydrogen storage reaction of MgH2. The prepared TiVO3.5 inherits the layered morphology of its MXene precursor, but the layer surface becomes very coarse because of the presence of numerous nanoparticles. Adding a minor amount of TiVO3.5 remarkably reduces the dehydrogenation and hydrogenation temperatures of MgH2 and enhances the reaction kinetics. The 10 wt% TiVO3.5-containing sample exhibits optimal hydrogen storage properties, as it desorbs approximately 5.0 wt% H2 in 10 min at 250 °C and re-absorbs 3.9 wt% H2 in 5 s at 100 °C and under 50 bar of hydrogen pressure. The apparent activation energy is calculated to be approximately 62.4 kJ/mol for the MgH2-10 wt% TiVO3.5 sample, representing a 59% reduction in comparison with pristine MgH2 (153.8 kJ/mol), which reasonably explains the remarkably reduced dehydrogenation operating temperature. Metallic Ti and V are detected after ball milling with MgH2; they are uniformly dispersed on the MgH2 matrix and act as actual catalytic species for the improvement of the hydrogen storage properties of MgH2.

Low-carbon Stellite alloys such as Stellite 21 exhibit good high-temperature and corrosion properties but need improved wear resistance in some applications. In this research, two low-carbon Stellite alloys with highly increased molybdenum content are produced via laser cladding. The microstructures of the laser cladding hardfacings are studied using scanning electron microscopy (SEM) with an energy dispersive X-ray (EDS) spectroscopy, and X-ray diffraction. The wear resistance of the hardfacings is evaluated using a pin-on-disc tribometer. The corrosion performance of the hardfacings is investigated under electrochemical tests in 3.5 wt.% sodium chloride (NaCl) solution and in Green Death solution. The experimental results show that the presence of Mo-rich intermetallic compounds enhances the wear resistance of the alloy hardfacings significantly. Since Stellite alloys are all able to form protective oxide films due to high chromium content against corrosion of the substrates, the bonding strength and repair ability of the oxide films dominate the corrosion resistance of the hardfacings in the corrosive environments. Stellite 21 hardfacing is also studied under the same testing conditions for comparison.

Carbon-supported nanocrystalline TiO2 (TiO2@C) shows good catalytic activity in the hydrogen storage reaction of MgH2. Adding a small amount of carbon-supported nanocrystalline TiO2 remarkably reduces the dehydrogenation operating temperatures because the MgH2-10 wt% TiO2@C sample starts releasing H2 at 205 °C, which is 95 °C lower than that of pristine MgH2. At 300 °C, the 10 wt% TiO2@C-containing sample rapidly releases 6.5 wt% hydrogen within 7 min. More importantly, the dehydrogenated 10 wt% TiO2@C-containing sample takes up hydrogen even at room temperature and under a hydrogen pressure of 50 bar, and approximately 6.6 wt% hydrogen is absorbed within 10 min at 140 °C. Kinetic measurements reveal a 30% and 50% reduction in the apparent activation energy of the dehydrogenation and hydrogenation of MgH2, respectively, with the presence of 10 wt% TiO2@C additive. Density functional theory calculations present the extended bond lengths and the reduced bond strengths for Mg-H bonding when MgH2 adsorbs on the TiO2 clusters, which is responsible for the reduced de-/hydrogenation temperatures of the TiO2@C-containing MgH2.

Recently, the low cost energy devices with high energy density and high power density are becoming more and more important in the field of electric vehicles. In this work, the electrochemical intercalation/deintercalation behaviors of PF6ˉ into graphitic mesocarbon microbead (MCMB) cathode are investigated in the electrolyte of 1 M LiPF6 in the mixed solvent of ethylmethyl carbonate and sulfolane. The charge storage mechanisms related to surface-limited capacitive and diffusion-controlled intercalation capacity are also studied by cyclic voltammetry measurements, which indicates that both the intercalation reaction and the capacitive reaction contribute to the overall capacity. Furthermore, dual-carbon batteries comprising MCMB cathode and pre-lithiated MCMB anode are unprecedentedly demonstrated in the form of aluminum pouch cells with laminated structure and exhibit an encouraging energy density of 47.9 Wh kg−1 at the power density of 583.6 W kg−1 based on the overall mass of the battery. Finally, electrochemical impedance spectroscopy is used to differentiate the resistance variation of MCMB cathode and MCMB anode before and after 3000 cycles. The continuous intercalation/deintercalation of PF6ˉ into MCMB cathode lead to the exfoliation of the active material and the increase of internal resistance.

The influence of the Ti alloy substrate (α, β, α + β) on the anodic oxidation process was studied. The surface morphology, composition and crystalline structure were analyzed by scanning electron microscopy (SEM), transmission electron microscopy (TEM), atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS). It was shown that the surface morphology and crystalline structure of anodic oxide films were considerably affected by the Ti alloy substrate. The surface morphologies of the oxide films retain their matrix microstructure characteristics. The oxide film on the residual β phase contains a trace amount of V, Zr, Mo element for TA15. Compared to the secondary α phase, the β phase has a higher degree of oxidation for TB6. The oxide film has the higher Al content on the secondary α phase, while the oxide film formed on β-phase has the higher V content. The XPS results show that the Al, Mo, V, Zr alloy elements of TA15 are involved in anodic oxidation and exist as Al2O3, MoO3, V2O5, ZrO2. Likewise, the Al, V alloy elements of TB6 are involved in anodic oxidation and exist as Al2O3, V2O5, but Fe element is not involved in anodic oxidation. The anodic oxide films are partly crystallized and mainly amorphous for the three kinds of titanium alloys. The TA15 anodic oxide film has the highest crystal content, and TB6 has the least.

Emerging evidence showed that cardiac proliferation played a significant role in the cardiac rehabilitation and repair. Extracellular vesicles (EVs) are known to regulate multiple cell functions, whereas the role of EVs in cardiac proliferation still remains unclear. In this study, we found that serum EVs promoted cell proliferation in rat heart myoblastic H9C2 cells with significantly increased expression level of miR-17-3p. Inhibition of miR-17-3p could decrease H9C2 cells proliferation induced by serum EVs. Additionally, we found that TIMP3 was a target of miR-17-3p in H9C2 cells proliferation and the expression of TIMP3 was downregulated by serum EVs. Meanwhile, inhibition of TIMP3 increased cardiac proliferation. In conclusion, results of our study indicated that serum EVs could promote the proliferation of H9C2 cells via regulating miR-17-3p/TIMP3, which may be a potential therapeutic target for treatment of cardiac injury.

The distribution of WC particles in laser cladded composite coatings can significantly affect the wear resistance of the coatings under aggressive environments. In this study, pre-alloyed WC-NiCrMo powder is deposited on SS316L via laser cladding with circular spot and wide-band spot, respectively. The microstructure and WC distribution of the coatings are investigated with optical microscope (OM), scanning electron microscopy (SEM), energy dispersive spectrometer (EDS), and X-ray diffraction (XRD). The wear behavior of the coatings is investigated under dry sliding-wear test. The experimental results show that the partially dissolved WC particles are uniformly distributed in both coatings produced with circular spot and wide-band spot, respectively, and the microstructures consist of WC and M23C6 carbides and γ-(Ni, Fe) solid solution matrix. However, due to Fe dilution, the two coatings have different microstructural characteristics, resulting in different hardness and wear resistance. The wide-band spot laser prepared coating shows better performance than the circular spot laser prepared coating.

Graphene-wrapped iron carbide nanoparticles (Fe3C@G) are employed as an alternative counter electrode to Pt in dye-sensitized solar cell via a convenient magnetic field induced assembly method. Benefit from the novel binder-free electrode fabrication route, the Fe3C@G nanosheets orderly are deposited on the FTO glass to form an effective catalyst layer with both favorable catalytic ability and electron migration rate. Comparable photovoltaic conversion efficiency with Pt endows the Fe3C@G a promising counter electrode for low cost but high performance dye-sensitized solar cells. Moreover, the magnetic field induced assembly method also shows potential application for other magnetic materials towards counter electrode.

Depositing hard materials such as Stellite-6 solely by cold spray (CS) is challengeable due to limited ability of plastic deformation. In this study, the deposition of Stellite-6 powder was achieved by supersonic laser deposition (SLD) which combines CS with synchronous laser irradiation. The surface morphology, deposition efficiency, track shape of Stellite-6 coatings produced over a range of laser irradiation temperatures were examined so as to reveal the effects of varying laser energy inputting on the deposition process of high strength material. The microstructure, phase composition and wear/corrosion resistant properties of the as-deposited Stellite-6 coatings were also investigated. The experimental results demonstrate that the surface flatness and deposition efficiency increase with laser irradiation temperature due to the softening effect induced by laser heating. The as-deposited Stellite-6 tracks show asymmetric shapes which are influenced by the relative configuration of powder stream and laser beam. The SLD coatings can preserve the original microstructure and phase of the feedstock material due to relatively low laser energy inputting, which result in the superior wear/corrosion resistant properties as compared to the counterpart prepared by laser cladding.

Objectives We sought to examine the relationship between visceral adipose tissue (VAT) and vascular inflammation (VI) by 18 fluorodeoxyglucose ( 18 FDG) positron-emission tomography (PET)/computed tomography (CT) in psoriasis (PSO). Furthermore, we evaluated whether treatment of PSO modulated VAT and VI. Background PSO, a chronic inflammatory skin disease, is associated with VI by 18 FDG PET/CT and increased cardiometabolic risk including adipose tissue dysregulation. Recently, VI was associated with future cardiovascular events; however, the relationship of visceral and subcutaneous adiposity with VI in PSO has yet to be evaluated. Methods Consecutive PSO patients (N = 77) underwent 18 FDG PET/CT scans to measure VI and abdominal adiposity. A subset of PSO patients with severe skin disease was scanned at 1 year following PSO treatment (N = 13). Results The cohort was middle aged (51.8 ± 12.6 years), predominantly male (n = 44, 57%), had low cardiovascular risk by Framingham 10-year risk (median 4 years [interquartile range (IQR): 2 to 7 years]), and mild-to-moderate skin disease (5.2 [IQR: 3.0 to 8.5]). PSO disease severity associated with VAT (β = 0.33; p = 0.004) beyond SAT (β = 0.30; p = 0.005). VAT (β = 0.55; p Conclusions Volume-based CT measurement of VAT may capture metabolic risk associated with VI compared to subcutaneous adipose tissue in PSO. PSO treatment associated with a decrease in VAT as well as decrease in VI suggesting VAT as a relevant biomarker related to VI in PSO.

A Stellite alloy mixture hardfacing consisting of 70% Stellite 3 and 30% Stellite 21, is created via laser cladding for control valve seat sealing surfaces, aiming at enhancing hardness and wear resistance compared with Stellite 6, and improving cracking in laser cladding compared with Stellite 3. The Stellite alloy mixture hardfacing is made on 316 stainless steel substrate and does not show any cracking in liquid penetrant testing. The microstructure of the hardfacing is analyzed using SEM, EDS and XRD. The hardness, dry sliding wear resistance, cavitation-erosion resistance in NaOH solution and corrosion resistance in morpholine solution at pH 9.5 to simulate the amine environment of boiler feedwater service in power generation plants, are evaluated. The Stellite 6 hardfacing prepared with the same laser process parameters is also analyzed and tested under the same conditions for comparison. The experimental results and real industrial test demonstrate superior performance of the Stellite alloy mixture hardfacing to the Stellite 6 hardfacing for control valve seat sealing application.

During the laser cladding process, complex transport phenomena occur in the molten pool including strong convection, substrate melting, melt solidification, species transport, etc., which determine the final distribution of solute concentration in the cladding layer. In this study, a three-phase Eulerian volume averaging approach was developed to investigate laser cladding with 316L steel powder on 45 steel substrate. The numerical results were validated by experimental results in terms of the geometrical morphology and chromium concentration of the cladding layer. The numerical results indicate that two distinct vortexes, driven by Marangoni force, lead to two mixing stages, i.e., the premixing stage in the front of the molten pool and the fully mixing stage in the rear of the molten pool. Both of the two mixing stages have significant effects on the final distribution of compositions in the cladding layer. Meanwhile, due to the inadequate mixing of all the compositions in the molten pool, heterogeneous composition distribution of chromium was observed both in the experimental and simulated results.

H13 tool steel is often damaged by wear, erosion and thermal fatigue, and laser hybrid additive remanufacturing is an effective method to repair damaged locations to extend their service lives. In this study, the Fe-based layer with Ni-based transitional layer is fabricated in the surface layer of H13 tool steel by laser cladding (LC). Subsequently, massive laser shock peening treatment (MLSPT) is applied to improve the mechanical properties of the LCed coating. Meanwhile, the effects of MLSPT on the residual stress, micro-hardness, microstructure and wear performance are systematically investigated. Results indicate that after MLSPT, the residual stress is transformed from tensile to compressive state, and high-density dislocations and a large number of mechanical twins are generated in the coating. MLSPT-induced surface nanocrystallization contributes to the improvement of micro-hardness and wear resistance of the LCed Ni25/Fe104 coating, and the grain refinement and wear property enhancement mechanisms are also revealed.

Supersonic laser deposition (SLD) is a relatively new material deposition technique, which combines laser irradiation with cold spray (CS). The solid-state manufacturing of continuous and dense WC/Stellite-6 composite coatings was achieved by SLD in this study. The comparison between the WC/Stellite-6 composite coatings produced by SLD and laser cladding (LC) respectively was conducted with respect to microstructure, phase composition, microhardness, cracking susceptibility, and tribological behaviors, thus to elucidate the role of laser irradiation in the SLD process. The experimental results show that the SLD coating has fewer defects, higher WC content, lower cracking susceptibility and better wear-resistant performance than the counterpart prepared by LC, which benefits from the preservation of microstructures and phase compositions of the feedstock materials due to the relatively low heat involved in SLD process. Moreover, due to the additional heat provided by laser irradiation, the bonding mechanism in SLD evolves from dominant mechanical bonding in CS to coexistence of mechanical and metallurgical bonding.

An advanced particle distribution controlling approach is proposed for laser melt injection process, which applies an electric-magnetic compound field to assist the laser melt injection process. The electric-magnetic synergistic effect on the reinforcement particle distribution in laser melt injection is investigated using numerical and experimental methods. Spherical WC particles are used as the reinforcement and their distribution in the longitudinal sections of the laser melt injection layers is examined with SEM and studied with computer graphics processing. The distributions of fluid temperature, fluid velocity and reinforcement particles in the molten pool are simulated using a 2D multi-physics model coupled with the equations of heat transfer, fluid dynamics, drag force, Lorentz force and phase transition. The results show that, the directional Lorentz force due to an electric-magnetic compound field, as a sort of volume force, can change the equivalent buoyancy acting on the particles. When the Lorentz force and gravity force are in same direction, majority of particles are trapped in the upper region of laser melt injection layer, while when the Lorentz force and gravity force are in opposite direction, most particles are concentrated in the bottom region. As a result, the distribution gradient of WC particles can be controlled by the electric-magnetic compound field, instead of the time-consuming adjustment of process parameters.

A series of adenosine analogues were synthesized and their biological evaluation was tested against Coxsackie virus B3 (CVB3) and Herpes simplex virus type 1(HSV-1) in HEp-2 cells. The hydrophobic constant, acute toxicity, carcinogenicity and mutagenicity were calculated. Analogues with piperazine derivatives 8b showed promising activities against CVB3 with a lower IC 50 value and higher selectivity index, their efficacy was better than that of the commercialized medicine, Ribavirin. These described adenosine analogues exhibit potent antiviral activities against several viruses, and offer new leads for further development.

Stellite-6 coatings were deposited on 17-4 PH stainless steel substrate by supersonic laser deposition (SLD) and laser cladding (LC) to improve cavitation resistance of the substrate. The microstructural characteristics of the as-deposited coatings were analyzed on the basis of OM, SEM, EBSD, XRD, Vicker’s hardness and nano-indentation results. The cavitation erosion performances in 3.5 wt% NaCl solution were comparatively investigated by a vibratory apparatus for the coatings prepared by SLD and LC technologies. The underlying mechanisms for differences of cavitation behavior between these two samples were elucidated in terms of grain size, dilution level, phase composition, hardness, elastic modulus and topographical features of the worn surfaces. Results show that SLD coating has finer grain, lower dilution and higher ratio of hardness to modulus. By analyzing the eroded surfaces, it is found that the pores formed due to mechanical bonding between particles in SLD coating are the priority position of cavitation where bubbles nucleate, grow and collapse. Repeated impact force from bubble collapse produces cracks and makes cracks propagation, leading to particle detachment and finally material removal. Although the porosity of SLD coating is higher than that of LC coating, its content is only less than 0.4%. Therefore, the negative effect of porosity is weaker than the positive effect of grain refinement, low dilution ratio and high hardness on cavitation performance. Consequently, SLD coating has better cavitation resistance than LC coating.

In this research, the hot corrosion behavior of laser deposited Inconel 718 alloy under different heat treatment conditions (solution plus aging, direct aging and as-deposited) is investigated in a salt mixture of Na2SO4 (87.5 wt.%) + NaCl (5 wt.%) + NaVO3 (7.5 wt.%) at 650 °C. The weight changes of the Inconel 718 specimens that have experienced different heat treatments are measured during the hot corrosion experiments and the data of the weight changes are used to determine the kinetics of the hot corrosion. Field emission scanning electron microscope (FE-SEM) with energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD) are employed to characterize the corrosion products of the specimens, thus the corrosion mechanisms are analysed. It is shown that the hot corrosion kinetic of the as-deposited Inconel 718 alloy follows a parabolic law. The element mapping results of the corroded surfaces reveal that the corrosion products of as-deposited Inconel 718 include two distinct layers, of which the outermost layer is mainly composed of Ni2CrO4, Cr2O3 and Fe3O4, while the inner layer contains Ni3S2. The laser deposited Inconel 718 alloys with different heat treatments behave differently in the hot corrosion. The hot corrosion performance of the solution treated specimens is better than that of the directly aged specimens, while the latter has better hot corrosion resistance than the as-deposited specimens. According to the hot corrosion test results and theoretical analyses, the hot corrosion behavior of as-deposited Inconel 718 alloy with different heat treatments in the salt mixture solution is closely related to basic fluxing mechanism, sulphidation and oxidation as well.

Preferential interdendritic oxidation of as-built additively manufactured Inconel 718 is observed. Interdendritic depletion of Cr and enrichment of Ti are responsible for a slow formation of fine-grain Cr2O3 external scale that aids the establishment of a high-level oxygen partial pressure along the interdendrtic region. Incomplete oxidation of carbides results in a large volume expansion. Oxidation of Laves phases leads to a discontinuous NbO interlayer that facilitates countercurrent diffusion channels. Preferential interdendritic oxidation dramatically promotes oxidation kinetics of both transient- and diffusion-controlled stages. Measures to homogenize the composition and to control the primary precipitates are desired to improve the oxidation performance.

H13 extrusion dies are often damaged by wear, erosion and thermal fatigue, and laser additive remanufacturing is an effective method to repair damaged locations to extend their service lives of H13 steel dies. In this study, Fe-based coatings are fabricated on the surface of H13 extrusion punches by laser cladding using the Fe-based powder mixed with M2 powder of different contents, and the effects of the M2 powder on the phase compositions, tensile properties, wear performance and thermal fatigue life are systematically investigated. Results indicate that the refined structures and various types of carbides are contained in all Fe-based coatings after adding M2 powder. Compared with other three coatings, the Fe-based coating mixed with 15 wt% M2 powder exhibits better thermal fatigue life. As a consequence, an influence mechanism of M2 powder on microstructural evolution and mechanical property is also presented in detail.

Laser shockwave cleaning (LSC) has been gaining increasing attention due to its advantages in decontaminating various micron- and nano-scale contaminated particles on silicon (Si) wafer surfaces. However, the particles in a blind zone right under the laser-induced plasma, the origin of the shockwave, cannot be removed efficiently, thereby impeding the conventional LSC process in industrial wafer cleaning applications. Here, we demonstrate a simple but intriguing method of eliminating the blind zone in nanoparticle removal on Si wafers by employing a double-beam laser shockwave cleaning process (DLSC). The size of the uncleaned blind zone in DLSC is reduced by 98% compared to the traditional single-beam LSC (SLSC) process with a laser pulse energy of 150 mJ and a gap distance between the laser focus and the wafer of 1 mm. The time-resolved, laser-induced plasma evolution reveals that the steady single-laser-beam-induced plasma splits into multiple plasma kernels distributed around the focus point due to the disruption from the second laser beam. The formation of multiple plasma kernels makes it possible to expose the particles in the blind zone to the cleaning-effective zone of the shockwave from a nearby passing plasma. The angle between the two laser beams plays a critical role in eliminating the blind zone. The comparison of the particle removal force between DLSC and SLSC suggests that the horizontal drag force from a nearby passing plasma acts on the particles in the blind zone and facilitates their removal.

Lithium ion capacitors (LICs), which bridge the gap between lithium ion battery and electric double layer capacitor, have recently attracted considerable attention. Herein, we first propose the possible utilization of nitrogen-doped carbonized polyimide microsphere (CPIMS) as a novel anode material of LICs. The structures and lithium intercalation properties of CPIMS treated at different temperatures are investigated. It is demonstrated that some of nitrogen atoms are kept in the CPIMS, which is helpful for improving the electrochemical performances. The CPIMS900 (900 is the carbonization temperature) can deliver specific capacities of 328.3 and 48.2 mAh g −1 at 10 mA g −1 and 10 A g −1 , respectively. When the pre-lithiated CPIMS900 is coupled with an activated carbon cathode, an energy density of 28.5 Wh kg −1 at 348 W kg −1 is obtained based on the weight of both electrode materials. Even at 6940 W kg −1 , the energy density still remains 13.1 Wh kg −1 . After 5000 cycles at 500 mA g −1 , the capacity retention ratio is as high as 97.1%. The present work offers an opportunity to utilize the CPIMS material in LIC with high energy density, high power density and promising cycle life.

This paper presents a study of Stellite 6 powder deposited on medium-carbon steel over a range of laser deposition temperature, with emphasis on investigating the role of laser irradiation in the supersonic laser deposition (SLD) process. The peak coating thickness and the microhardness of the coating specimens produced with different deposition temperatures are measured to investigate the influence of laser irradiation on the coating characteristics. The coating bonding behavior is assessed via the analysis of interfacial element diffusion and fractured surface morphology under three-point-bending test. The results show that increasing the deposition temperature can improve the deposition efficiency significantly and induce interfacial element diffusion, which implies that the introduction of laser heat into cold spray (CS) permits a change in the thermodynamic state of impacting particles and substrate, thereby provides good interface bonding at lower velocities as compared with the CS process. This research finds that SLD is capable of producing Stellite 6 hardfacing with combined mechanical and metallurgical bonding.