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Short channel platelet SBA-15 mesoporous material is one of the effective adsorbent for the recovery of U(VI) from aqueous solution. Nevertheless, the defect is that the mesoporous size limits the total stripping of attached U(VI) in recycling use and the increasing densities of organic groups after functionalization. Thus, a simple and controllable method was adopted to prepare SBA-15-type material with expanded pore channel by adding trimethylbenzene in synthesis procedure. The structure, morphology and functional groups were characterized by scanning electron microscope, powder X-ray diffraction, thermogravimetric analysis, transmission electron microscope, FTIR and N2 adsorption-desorption isotherm analysis. Furthermore, the adsorption behavior of obtained product was test under various factors such as initial concentration, pH, elution rate and contact time. The pore expanded platelet SBA-15 exhibited higher U(VI) adsorption capacity, higher elution rate, and more bearing of amidoxime groups. Due to the higher amidoxime groups, the adsorption capacity of U(VI) on the amidoxime functionalized pore-expanded SBA-15 was 674mg-U g−1. The results show that the simple and controllable pore-expanded method is an effective strategy to enhance the elution effect and increase grafting amount of organic groups on the mesoporous materials.

Mesenchymal stem/stromal cells (MSCs) hold great promise and clinical efficacy in bone/cartilage regeneration. With a deeper understanding of stem cell biology over the past decade, epigenetics stands out as one of the most promising ways to control MSCs differentiation. Trithorax group (TrxG) proteins, including the COMPASS family, ASH1L, CBP/p300 as histone modifying factors, and the SWI/SNF complexes as chromatin remodelers, play an important role in gene expression regulation during the process of stem cell differentiation. This review summarises the components and functions of TrxG complexes. We provide an overview of the regulation mechanisms of TrxG in MSCs osteogenic and chondrogenic differentiation, and discuss the prospects of epigenetic regulation mediated by TrxG in bone and cartilage regeneration.

To investigate whether and how global O-linked N-Acetylglucosamine modification (O-GlcNAcylation), a prevalent nutrient-sensitive post-translation modification, regulates odontogenic differentiation and mineralization in human dental pulp cells (hDPCs).First, immunostaining assays on sections of dental pulp tissue were performed to detect the distributions of O-GlcNAcylation and its exclusive enzyme set O-GlcNAc transferase (OGT) and O-GlcNAcase (OGA). Then global O-GlcNAcylation was determined by anti O-linked N-Acetylglucosamine (RL2) Western blot during odontogenesis of hDPCs. Further, inhibition or knockdown of OGT and OGA were achieved by specific inhibitors or siRNA in vitro, respectively. The odonto-induction effect of O-GlcNAcylation ex vivo was investigated by a subcutaneous transplantation experiment. Moreover, the O-GlcNAc modification of RAPTOR was confirmed by immunoprecipitation. Odontogenic differentiation assays also investigated the indispensable role of RAPTOR during enhanced global O-GlcNAcylation.The signals of O-GlcNAc became more enriched in the odontoblasts compared to pulp fibroblasts. During odontogenesis of hDPCs, global O-GlcNAcylation was significantly increased. An increase or decrease of O-GlcNAcylation significantly boosted or blunted odontogenic differentiation, respectively. The fluctuation of O-GlcNAcylation continuously impacted the downstream targets of mTORC1. Consistently, RAPTOR was modified by O-GlcNAcylation, which was necessary for inducing odontogenesis.Global O-GlcNAcylation participated in and affected the odontogenic differentiation of hDPCs, which was mediated by the mTORC1 pathway. Thus, targeting O-GlcNAcylation might be a potential therapeutic intervention for pulp repair and regeneration.

Transformation Induced Plasticity (TRIP)-assisted annealed martensitic (TAM) steel sheets with various microalloying additions such as niobium, vanadium, or titanium were prepared on laboratory scale and subjected to a double-quenching and austempering heat treatment cycle. Slow strain rate tensile (SSRT) was tested on the investigated TAM steels with and without hydrogen charging to reveal their tensile behaviors and hydrogen induced embrittlement effects. Microstructure observations by scanning electron microscope (SEM) are composed of a principal annealed martensitic matrix and 11.0–13.0% volume fraction of retained austenite, depending on the type of microalloying addition in the different steels. SSRT results show that these TRIP-assisted annealed martensitic steels under air media conditions combine high tensile strength (>1000 MPa) and good ductility (~25%), while under hydrogen charging condition, both tensile strength and ductility decrease where tensile strength ranges between 680 and 760 MPa, down from 1000–1100 MPa, and ductility loss ratio is between 78.8% and 91.1%, along with a total elongation of less than 5%. Hydrogen charged into steel matrix leads to the appearance of cleavage fractures, implying the occurrence of hydrogen induced embrittlement effect in TAM steels. Thermal hydrogen desorption results show that there are double-peak hydrogen desorption temperature ranges for these microalloyed steels, where the first peak corresponds to a high-density dislocation trapping effect, and the second peak corresponds to a hydrogen trapping effect exerted by microalloying precipitates. Thermal desorption analysis (TDS) in combination with SSRT results demonstrate that microalloying precipitates act as irreversible traps to fix hydrogen and, thus, retard diffusive hydrogen motion towards defects, such as grain boundaries and dislocations in microstructure matrix, and eventually reduce the hydrogen induced embrittlement tendency.

Certain cold-worked martensitic Ti-alloys exhibit tunable linear thermal expansion along a specific sample direction. These intriguing properties are related to the anisotropic thermal expansion of the orthorhombic αʺ martensite. However, the tailored expansion obtained in this way is limited to the single-phase martensitic temperature field, below the reverse transformation of martensite into austenite. Here, we demonstrate that the orthorhombic αʺiso formed by diffusion can also regulate the thermal expansion using a prototypical Ti22Nb alloy. More importantly, the temperature range in which the tailored linear thermal expansion occurs is enormously broadened relative to the cold-worked martensitic alloy. We clarify the formation path of nano-sized αʺiso during thermal cycling and resolve the crystallographic relationship with the parent phase. These findings provide new routes for designing low/negative thermal expansion Ti-alloys with large operating temperature ranges.

The reconstruction of large bone defects remains a crucial challenge in orthopedic surgery. The current treatments including autologous and allogenic bone grafting and bioactive materials have their respective drawbacks. While mesenchymal stem cell (MSC) therapy may address these limitations, growing researches have demonstrated that the effectiveness of MSC therapy depends on paracrine factors, particularly exosomes. This aroused great focus on the exosome-based cell-free therapy in the treatment of bone defects. Exosomes can transfer various cargoes, and noncoding RNAs are the most widely studied cargo through which exosomes exert their ability of osteoinduction. Here, we review the research status of the exosome-derived noncoding RNAs in bone regeneration, the potential application of exosomes, and the existing challenges.

A surface hydroxylation process with an alkali solution of low concentration was employed to recover surface silanol groups of SBA-15 prior to amidoxime (AO)-functionalization. The effect of concentration and temperature on surface hydroxylation were investigated, and the optimal conditions of 0.003 mol L−1 and 65 °C for the surface hydroxylation were determined. The silanol density was increased from 1.20 mmol g−1 of the untreated SBA-15 to 1.45 mmol g−1 of the hydroxylated SBA-15. Characterizations through scanning electron microscopy, transmission electron microscopy, X-ray diffraction, N2 adsorption-desorption proved that the hydroxylation process did not destroy mesopore structure and morphology of SBA-15. The hydroxylated SBA-15 could anchor more AO groups than the untreated SBA-15, resulting in higher U(VI) adsorption capacity (709 mg g−1) of the pristine AO-functionalized SBA-15 following hydroxylation than that of untreated sample (601 mg g−1). The adsorption capacity of the regenerated samples slightly decreased after three sorption-desorption cycles. Compared with other coexisting cations (Na+, K+, Mg2+, and Ca2+) in artificial seawater with rich uranium, the distribution coefficient (Kd) and concentration factor (CF) value of UO22+ were far larger, suggesting high selectivity of AO-H-SBA-15 for UO22+. These results indicate that the surface hydroxylation process can enhance U(VI) adsorption maintaining the high adsorption selectivity and long-term adsorption stability.

In the present work, a high performance martensite-austenite steel was produced by utilizing optimized quenching and partitioning (Q&P) process, and its impact-abrasive wear behavior was investigated in comparison with commercial Hadfield steel (Mn13Cr2) under 2 J and 4 J impact energies. Tensile tests, scanning electron microscope (SEM), transmission electron microscope (TEM) and X-ray diffraction (XRD) were applied to characterize mechanical properties, microstructure evolution, and wear mechanisms of the two steels. Experimental results revealed that the Q&P steel with martensite matrix and retained austenite (RA) had higher strength properties and better impact-abrasive wear resistance than Mn13Cr2. During impact-abrasive wear tests, wear mass loss was less under higher impact energy for both steels, and the Q&P steel owned less wear mass loss than Mn13Cr2. The main strengthening mechanisms were newly formed martensite twins (RA to martensite transformation) and high density dislocations for the Q&P steel, and the interactions of twinning and dislocation structures were for Mn13Cr2, respectively.

The stress partitioning among ferrite, martensite and retained austenite, and the stability of retained austenite under uniaxial tensile loading of a TRIP-assisted multiphase steel are investigated using in-situ high-energy X-ray diffraction technique. The results indicate that the stress partitioning, mainly occurring in elastic and elastoplastic regions, is activated by the “stress feedback mechanism”. In the elastic region, the decline of increasing rate of ferrite stress is accompanied by the sudden increase of martensite and retained austenite stresses, which indicates a stress transfer from ferrite to martensite and retained austenite. During deformation, martensitic transformation first occurs in the retained austenite with low carbon content, followed by those with high carbon content, which is denominated “selective transformation mechanism”. In addition, the increment of average carbon content in retained austenite continuously increases with the gradual transformation of retained austenite into martensite. The evolution of retained austenite strain versus engineering stress is similar to that of martensite strain, except that austenite strain is higher than martensite strain at the end of uniform deformation, which is related to the high carbon content in retained austenite.

Controlling the amount of retained austenite and precipitate particles allows for tailoring of mechanical properties in medium Mn steel alloyed with Cu, Ni and Al. The austenite reversion and precipitation/dissolution occur simultaneously during aging treatment at 550 °C being lower than Ac1. The degree of austenite transformation depends on the diffusion of austenite stabilizing elements (Mn, Cu and Ni), and the dissolution of the precipitate particles promotes the diffusion. Small angle neutron scattering (SANS) measurements were performed at the China Spallation Neutron Source (CSNS) to investigate the precipitation/dissolution behaviors. A large number of precipitate particles form at the aging time of 1 h, and then the volume fraction of the particles continuously decreases, and the average particle size has little change as holding time increases, indicating the dissolution of the precipitate particles. Atom probe tomography and transmission electron microscopy were used to study the type, composition and distribution of the precipitate particles. The particles contain Cu and NiAl-type precipitates, which have BCC and B2 structures, respectively. The characterization and modeling of austenite reversion kinetics indicate that austenite transformation is mainly controlled by the diffusion of Cu, which is promoted by the dissolution of Cu particles. This work offers significant insights towards an austenite-precipitate cooperative design for controlling the mechanical properties of the steel.

Intercritical annealing, quenching and partitioning (IQ moreover, the formation of TiC consumes the carbon atoms pinning the dislocations and thus has an important effect on the yield strength and yield platform. This work is essential for suppressing the formation of transition iron carbides, understanding the precipitation characteristics of TiC and designing the I&QP steel with improved mechanical properties.

The effect of carbon at interface of austenite on manganese segregation was investigated. Carbon segregating at interface of retained austenite within ferrite grains can attract manganese atoms to form atomic couples C-Mn filling into vacancies. C and Mn segregation can make the interface of austenite more stabilization so that the interface cannot transform to twin martensite under 20% pre-straining. The interface can act as deformation buffer zones to make for plasticity accommodation between ferrite and twin martensite leading to improved ductility of the steel.

This paper presents a detailed investigation of the transformation behavior of retained austenite at different locations of intercritical heating, quenching and partitioning (IQ however, the values are not more than 0.7° at 15% and 20% strain due to the TRIP effect. For the retained austenite within ferrite grains, the interior part preferentially transforms into twin martensite, while the interface still remains due to alloying elements segregation.

Aminophend/formaldehyde resin polymeric nanospheres (APFNSs) synthesized by the sol-gel method with monomers of 3-aminophenol and formaldehyde were used as nanofillers incorporated into polyamide (PA) layers to fabricate thin-film nanocomposite (TFN) membranes via interfacial polymerization of trimesoyl chloride (TMC) and m-phenylenediamine (MPD). Due to the monomer of 3-aminophenol, the APFNSs are rich in hydroxyl and amino groups. Therefore, the APFNSs nanoparticles have good hydrophilicity and can react with TMC, resulting in chemically bonded to polyamide matrix of TFN membrane. The water flux of TFN-As membrane modified by APFNSs nanoparticles is 71.3 L/m2·h nearly twice of the pristine TFC membrane, and the salt rejection all keeps over 96%. TFN-As membranes also exhibit excellent anti-chlorine, anti-fouling and reuse performances. This work demonstrates that aminophend/formaldehyde resin polymeric nanospheres (APFNSs) can be used as a promising nanofiller for developing novel TFN membranes with improved desalination performance.

The effect of various multiphase microstructures on the fatigue properties of intercritical annealing, quenching and partitioning (IQ in TAM steel, the fatigue crack propagation (FCP) can be retarded when the crack passes through the mixed microstructure containing annealed martensitic laths and film-like retained austenite at an angle (not parallel); in TRIP steel, the crack branching and interlocking can hinder the FCP effectively, benefitting from bainite densely distributing in ferrite matrix as strengthening phase and the two phases having almost identical grain size. Therefore, the multiphase microstructure of TRIP steel has the best effect on retarding FCP among the three steels. The findings are essential for the optimization of multiphase microstructure in designing a steel with excellent fatigue properties.

Intercritical annealing, quenching, and partitioning (I&Q&P) parameters of transformation-induced plasticity (TRIP)-assisted steel were optimized using the Grey-Taguchi method. The optimum combination of mechanical properties was achieved after nine sets of experiments based on an orthogonal array. The influence of each factor was investigated based on the grey relational analysis, and the results indicated that quenching temperature had the most significant effect on the mechanical properties, followed by partitioning temperature and partitioning time. The stability of retained austenite (RA) and the strain hardening behavior during deformation were investigated to determine the origin of the best and worst mechanical properties from the orthogonal experiments. For the best mechanical properties, the stability of RA is the highest, and the TRIP effect occurs in almost all uniform deformation stages, benefiting from RA having various locations, morphologies, grain sizes, and orientation relationships with adjacent phases. For the worst mechanical properties, a large amount of TiC precipitation occurs, which consumes a portion of the carbon atoms partitioning from the supersaturated martensite to austenite, resulting in the lowest carbon content and stability of RA. The findings can provide a new method for accurately and effectively optimizing the processing parameters and analyzing their influence on mechanical properties.

In the present work, the tensile deformation characteristics of the high performance multiphase steel with complex microstructures are investigated. A mixture of ferrite, bainite, and 14.4 vol% retained austenite (RA) with an average grain size of less than 3 μm of the matrix is obtained after specific heat treatment. Tensile tests are performed with increasing strain, i.e., 0%, 5%, 10%, 15%, and 20%. Then X-ray diffraction, transmission electron microscope and electron backscatter diffraction are utilized to analyze the deformation-transformation behaviors of the complex microstructures. Phase transformation of the RA, which is controlled by its morphology and distribution, contributes to high strain hardening capacity of the steel. The blocky-type RA that locates in ferrite grain boundaries shows less stability and transforms easily at early deformation stage, while the film-like RA that distributes between bainitic ferrite shows higher stability and transforms continuously throughout plastic deformation. Moreover, the substructure formation by dislocation configuration in ferrite grains begins with randomly distributed dislocations and ends up with cellular structures, resulting in ferrite subdivision during deformation and also grain refinement strengthening. As a result, the experimental steel is reinforced not only by the martensite transformation of RA, but also ferrite refinement.

In this study, multi-phase steel with a mixture of ferrite, bainite, retained austenite and martensite is obtained after specific heat treatments, which include intercritical annealing, isothermal holding and final quenching. The microstructural constituents and individual phase fractions are precisely quantified based on multi-scale characterizations. The focus is on bainite transformation kinetics and its impact on the microstructural evolution, which is systematically analyzed according to the assumption of displacive modeling theory. Bainite transformation begins with austenite grain-boundary nucleation and continues through autocatalytic nucleation based on nucleation kinetics of bainitic sub-units. A small discrepancy between the modeling and experimental results is indicative of carbon partitioning into austenite, which reduces the driving force and/or the rate parameter κ for bainite transformation. In addition, the continuous carbon enrichment in austenite decelerates the bainite transformation and prolongs the duration time. Moreover, the maximum carbon concentration in austenite is limited by the T0 line. Austenite with a lower carbon content but higher volume fraction will not transform to bainite at higher isothermal bainite transformation temperatures, and such mechanically unstable austenite is more likely to transform to martensite during final quenching. As a result, with increasing isothermal holding temperature, the bainite and retained austenite fractions decrease while the martensite fraction increases in the sepcimens after final quenching.

The newly designed 5% Cr steel processed by electro-slag casting can be a candidate material as components in blast furnace top gas recovery turbine unit (TRT). The present study focuses on the evolution of the microstructure, strength and toughness with increasing tempering temperature from 550 to 700 °C. Typical tempered martensitic structure was achieved after quenching and tempering for the 5% Cr steel. The microstructure characterization shows that M3C in the matrix after 550 °C tempering was not stable and transformed to M7C3 during tempering above 600 °C. After tempered at the temperature higher than 600 °C, only M7C3 existed in the specimens. The M7C3 carbides along the boundaries were significantly larger than those in the matrix due to the effect of direct nucleation as well as the greater mobility of alloy elements. The size and Cr content of M7C3 increased considerably with increasing tempering temperature. With the increase of tempering temperature, both tensile and yield strength decreased, which can be attributed to the recovery of martensitic laths and the decrease of the quantity of interstitial carbon atoms in the matrix as well as the coarsening of carbides. The softening of matrix and increase of the length of high angle grain boundaries were responsible for the increase of impact toughness. The integrated effects of the softening of matrix and coarsening of carbides resulted in the slight decrease of the impact absorbed energy after 700 °C tempering.

The effect of double quenching and tempering (DQT) treatment as well as conventional high temperature quenching and tempering (CQT) treatment on the microstructures and mechanical properties of low carbon 5Cr martensitic as cast steel produced by electroslag casting was investigated. The microstructure changes were characterized by optical microscope (OM), scanning electron microscope (SEM), electron back scatter diffraction (EBSD) and transmission electron microscopy (TEM). The characteristics of carbides precipitated during tempering were analyzed on both carbon extraction replica and thin foil samples by TEM. The mechanical performance was evaluated by Vickers hardness test, tensile test, and Charpy V-notch impact test at ambient temperature. The results of microstructure study indicated that DQT treatment led to a finer microstructure than that of CQT. The carbides of the tempered samples were identified as M 7 C 3 . The carbides along the prior austenite grain boundaries nucleated directly while those within the laths should be transformed from cementite which formed at the early tempering stage. Compared with CQT condition, yield strength slightly increased after DQT treatment, and impact toughness improved a lot. The strengthening mechanisms were analyzed and it was found that grain refining and precipitation strengthening were mainly responsible for the increase of strength. The superior toughness of DQT condition was attributed to the finer microstructure resulting in more frequent deflections of the cleavage crack and the smaller size of carbides along the prior austenite boundaries. EBSD analysis showed that both martensitic block and packet of low carbon 5Cr tempered martensitic steel could hinder crack propagation, while the latter was more effective.

The existing status of arsenic and the competitive mechanism between cementite (Fe 3 C) and grain boundaries to snatch arsenic in steel were investigated. It was shown that there was no arsenic segregation to grain boundaries in steel containing 0.023 wt% As, but arsenic tended to segregate to a position with more carbon. Physicochemical phase analysis confirmed that 85% of arsenic existed in Fe 3 C and the rest was in M(C,N). Fe 3 C has a competitive advantage over grain boundaries in terms of snatching the arsenic atoms, and it is an important factor in preventing arsenic grain boundaries segregation. Hence, it is concluded that arsenic dissolving into Fe 3 C weakens the grain boundaries segregation and this has no effect on the mechanical properties of the material within the range of the content of arsenic.