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The United States Department of Energy (DOE) has committed to expanding the domestic clean energy portfolio in response to the rising challenges of energy security in the wake of climate change. Accordingly, the construction of a series of Generation IV reactor technologies are being demonstrated, including sodium-cooled, small modular, and molten chloride fast reactors (MCFRs). To date, there are no fully qualified structural materials for constructing MCFRs. A number of commercial structural alloys have been considered for the construction of MCFRs, including alloys from the Inconel and Hastelloy series. Informed qualification of structural materials for the construction of MCFRs in the future can only be ensured by expanding the current fundamental knowledgebase of information pertaining to material performance under environmental stressors relevant to operation of the reactor, including corrosion susceptibility. The purpose of this investigation is to illustrate how a correlative multi-modal electron microscopy characterization approach, including the novel application of focused-ion beam 3D reconstruction capabilities, can elucidate the corrosion mechanism of a candidate structural material Inconel 617 for MCFR in NaCl-MgCl2 eutectic salt at 700°C for 1,000 h. Evidence of intergranular corrosion, Ni and Fe dealloying, and Cr-O enrichment along the grain boundary, which most likely corresponds to Cr2O3, is a phenomenon that has been documented in other Ni-based superalloys exposed to chloride molten salt systems. Additional corrosion products, including the formation of insoluble MgAl2O4, within the porous network produced by the salt attack is a novel observation. In addition, Mo3Si5 and τ2 precipitates are detected in the alloy bulk and are dissolved by the salt. Furthermore, the lack of detection of design γ′ precipitates in Inconel 617 after 1,000 h could indicate that the molten salt corrosion mechanism has indirectly induced a phase transformation of Al2TiNi (τ2) and Ni3(Al,Ti) (γ’) phase. This investigation provides a comprehensive understanding of molten salt corrosion mechanisms in a complex material system such as a commercial structural alloy for applications in MCFRs.

Retinal pigment epithelium (RPE) cell damage, including mitophagy-associated cell apoptosis, accelerates the pathogenesis of diabetic retinopathy (DR), a common complication of diabetes that causes blindness. Müller cells interact with RPE cells via pro-inflammatory cytokines, such as tumor necrosis factor α (TNF-α). Herein, we investigated the role of the RPE cell epidermal growth factor receptor (EGFR)/p38 mitogen-activated protein kinase (p38)/nuclear factor kappa B (NF-κB) pathway in Müller cell-derived TNF-α-induced mitophagy-associated apoptosis during DR. Our results showed that TNF-α released from Müller cells activated the EGFR/p38/NF-κB/p62 pathway to increase mitophagy and apoptosis in RPE cells under high glucose (HG) conditions. Additionally, blockade of the TNF-α/EGFR axis alleviates blood-retina barrier breakdown in diabetic mice. Our data further illustrate the effects of the Müller cell inflammatory response on RPE cell survival, implying potential molecular targets for DR treatment.

Background Total hip arthroplasty (THA) for bony ankylosis is technically challenging in patients with ankylosing spondylitis (AS). This study aimed to determine the mid-term results of bilateral synchronous THA for bony ankylosis in patients with AS. Methods Nineteen cases of bony ankylosis in patients with AS who received bilateral synchronous THA were included in this study (17 males and 2 females, mean age 49.2 years). Disease duration was 5–38 years (mean 18 years and 6 months). All patients received cementless THA. Intraoperative blood loss, visual analog scale (VAS) score, and complications were assessed. Harris hip scores evaluated the clinical effect. Results Patients were followed up for 62–98 months (mean 82.5 months). VAS score decreased from 7.42 ± 0.92 to 2.42 ± 0.83, Harris hip score improved from 21.8 ± 7.2 to 80.3 ± 6.5, and the flexion-extension range of the hip improved from 0 to 142.3 ± 6.2°. One patient with septum bronchiale had a fracture intraoperatively and was treated with wire strapping. One patient had a traction injury of the femoral nerve postoperatively and recovered 1 year after the operation. Loosening and subsidence were not observed in all patients. Heterotopic bone formation was noted in 3 patients. No complications such as joint dislocation, acute infection, and deep vein thrombosis were found. Conclusion Bilateral synchronous THA was effective for bony ankylosis of the hip in patients with AS because it improved patients’ quality of life and had satisfactory mid-term outcomes.

In pyroprocessing spent nuclear fuels by electrorefining in molten LiCl-KCl salt, it is desired to monitor in real time the UCl3 concentration in the salt for safeguards purposes. Current chemical analysis of the highly radioactive salt for electrorefining by an inductively coupled plasma technique is inconvenient and usually time-consuming in generating the salt composition results. In this paper, we evaluated whether a simple potentiometry approach can be used for real-time monitoring the concentration of GdCl3, which was used as a surrogate for UCl3, in LiCl-KCl-GdCl3 salt by measuring the open circuit potential of a Gd metal electrode with respect to a Ag/AgCl reference electrode (RE) when GdCl3 salt was incrementally added to the LiCl-KCl salt. Additions of LaCl3, CeCl3 and NdCl3 salts were used for evaluating the effects of other chloride salts on the selectivity of the Gd metal electrode vs Ag/AgCl RE. While using potentiometry to determine GdCl3 concentrations, Gd metal was unexpectedly observed to be unstable and dissolved in LiCl-KCl salt when GdCl3 is present.

Mumps is a vaccine-preventable disease caused by the mumps virus, but the incidence of mumps has increased among the children who were vaccinated with one-dose measles-mumps-rubella (MMR) in recent years. In this study, we analyzed the influence of different doses of mumps-containing vaccine (MuCV) against mumps using Cox-proportional hazard model. We collected 909 mumps cases of children who were born from 2006 to 2010 and vaccinated with different doses of MuCV in Quzhou during 2006-2018, which were all clinically diagnosed. Kaplan-Meier survival methods and Cox-proportional hazard model were used to estimate the hazard probabilities. Kaplan–Meier curves showed that the cumulative hazard of male and female has no difference; lower hazards were detected among those who were vaccinated with two-dose MuCV, born in 2006, and infected after supplementary immunization activities (SIA). Cox-proportional hazard regression suggested that onset after SIA, born in 2006, and vaccinated with two-dose MuCV were protective factors against infection even after adjusting for potential confounding effects. Our study showed that it was necessary to revise the diagnostic criteria of mumps and identify RT-PCR as the standard for mumps diagnosis in China. We suggested that routine immunization schedule should introduce two doses of MMR and prevaccination screening should be performed before booster immunization in vaccinated populations.

Diabetic retinopathy (DR) is a common complication of diabetes mellitus (DM), which results in vision loss. This study explored the role of miR-126 in high-glucose-induced human retinal endothelial cells (HRECs) and its underlying molecular mechanisms. The results showed that the expression levels of miR-126 and interleukin-17A (IL-17A) in high-glucose-induced HRECs were downregulated and upregulated, respectively. Functionally, overexpression of miR-126 promoted proliferation and suppressed apoptosis in high-glucose-induced HRECs, while IL-17A reversed the effects induced by miR-126. However, overexpression of IL-17A inhibited the proliferation and induced apoptosis, while knockdown of IL-17A accelerated the proliferation and repressed apoptosis. In addition, miR-126 repressed the expression of IL-17A, Bax, and caspase-3, while promoting the expression of survivin and phosphorylation of PI3K and AKT; restoration of IL-17A rescued these effects. Furthermore, IL-17A was identified as a target of miR-126. This indicates that miR-126 enhances proliferation and inhibits apoptosis in high-glucose-induced HRECs by activating the PI3K–AKT pathway, increasing survivin levels, and decreasing Bax and caspase-3 expression by targeting IL-17A, suggesting that miR-126 could be a novel target for preventing DR.

LiCl-Li2O salt is a widely used electrolyte for the electrochemical reduction of spent oxide (mainly uranium oxide) fuels, and the Li2O concentration is usually controlled at about 1.41 mol % for o...

Diabetic retinopathy (DR) is one of the most severe and common complications caused by diabetic mellites. Inhibiting NLRP3 inflammasome activation displays a crucial therapeutic value in DR. Studies have shown that KCNQ1OT1 plays a critical role in regulating NLRP3 inflammasome activation and participates in the pathogenesis of diabetic complications. The present study aims to explore the role, and the potential mechanism of KCNQ1OT1 in regulating the activation of NLRP3 inflammasome in DR. The expression of KCNQ1OT1 and the activation of NLRP3 inflammasome were increased in experimental DR models. KCNQ1OT1 knockdown alleviated NLRP3 inflammasome-associated molecules expression. In addition, KCNQ1OT1 was found to be localized mainly in the cytoplasm of Müller cells and facilitated TXNIP expression by acting as a miR-17-5p sponge. KCNQ1OT1 promoted the activation of NLRP3 inflammasome through miR-17-5p/TXNIP axis. Moreover, the clinical samples of patients with DR showed that the expression of KCNQ1OT1 and the activation of NLRP3 inflammasome were all increased, further supporting the hypothesis that the KCNQ1OT1 dysregulation may be the molecular mechanism of the pathogenesis of DR. Therefore, KCNQ1OT1 may serve as a new therapeutic target for DR.

Perovskite and spinel structures are widely found in ferroelectric and magnetic oxides, respectively, making their combination important for multiferroic composites. In this study, the (111) interface between perovskite-type $\mathrm{Bi}\mathrm{Fe}{\mathrm{O}}_{3}$ and spinel-type $\mathrm{Ni}{\mathrm{Fe}}_{2}{\mathrm{O}}_{4}$, has been systematically investigated at the atomic scale combining aberration-corrected scanning transmission electron microscopy and first-principles calculations. The atomic terminations at the interface were determined to be the $\mathrm{Bi}{\mathrm{O}}_{3}$ layer on the $\mathrm{Bi}\mathrm{Fe}{\mathrm{O}}_{3}$ side and the tetrahedral Fe layer on the $\mathrm{Ni}{\mathrm{Fe}}_{2}{\mathrm{O}}_{4}$ side. The lattice mismatch between $\mathrm{Bi}\mathrm{Fe}{\mathrm{O}}_{3}$ and $\mathrm{Ni}{\mathrm{Fe}}_{2}{\mathrm{O}}_{4}$ is primarily accommodated by the first and second $\mathrm{Bi}{\mathrm{O}}_{3}$ layers inside $\mathrm{Bi}\mathrm{Fe}{\mathrm{O}}_{3}$, indicating a stand-off of misfit dislocations in $\mathrm{Bi}\mathrm{Fe}{\mathrm{O}}_{3}$. A metallic interface is formed between the two insulating phases, with the $\mathrm{Bi}{\mathrm{O}}_{3}$ and tetrahedral Fe layer coupled antiferromagnetically across the interface. The magnetic moment in $\mathrm{Ni}{\mathrm{Fe}}_{2}{\mathrm{O}}_{4}$ and the ferroelectric polarization in $\mathrm{Bi}\mathrm{Fe}{\mathrm{O}}_{3}$ drop slightly at the interface and return to the bulk values within two atomic layers from the interface.

We report a disease outbreak caused by chikungunya virus in Zhejiang Province, China, in August 2017. Phylogenic analysis indicated that this virus belonged to the Indian Ocean clade of the East/Central/South African genotype and was imported by a traveler returning from Bangladesh.

Stress-induced structural phase transitions in multiferroic BiFeO3 thin films have attracted much attention for both fundamental research and promising applications in electronic devices. In this work, with the assistance of spherical aberration-corrected transmission electron microscopy, a tetragonal phase with the super large tetragonality (c/a ∼ 1.53) was found in the epitaxial BiFeO3 thin film on a LaAlO3/Si substrate. Analyses of atom positions showed that displacements of an Fe atom in this super tetragonal phase are much smaller than that in a regular tetragonal phase. First-principles calculations revealed that the structural phase transition occurs with the increasing lattice tetragonality c/a, accompanied by transitions in the atomic coordination and magnetic order.

Instrumentation to provide process monitoring (PM) and safeguards for the oxide reduction (OR) step in the electrochemical processing of used oxide nuclear fuel is necessary to ensure equipment is operated as declared. Cyclic voltammetry (CV) has been proposed for real-time monitoring of the operation of an OR process for safeguards purposes. In this study, 316L stainless steel (SS), tantalum (Ta), molybdenum (Mo), tungsten (W), platinum (Pt), and iridium (Ir) were evaluated as potential working electrode (WE) materials based on their chemical inertness, corrosion resistance, and sensitivity in detecting lithium oxide (Li2O) and other chloride salts in the OR electrolyte. Of the electrodes evaluated, 316L SS, Ir, and Pt all performed reasonably well in the lithium chloride-lithium oxide (LiCl-Li2O) electrolyte. SS was operated in the cathodic potential, had reasonable corrosion resistance, and is relatively inexpensive. Ir could be operated in both the cathodic and anodic potentials and was the most corrosion-resistant of the materials evaluated. Pt is limited to the anodic potential range, had reasonable corrosion resistance, and was the most sensitive to Li2O concentrations in the salt. In the development of a stand-alone safeguards instrumentation, our recommendation is a CV probe fitted with both Ir and Pt WEs. The results of this study may also be helpful for anode material selection in other electrometallurgy industries, such as molten salt electrolysis.

A modified phenomenological potential was constructed for BaTiO 3 -CaTiO 3 solid solution single crystal based on the Landau–Devonshire theory. The Ba 1−x Ca x TiO 3 solid solution phase diagram of temperature vs concentration ( T - x ) is obtained and shown to perfectly agree with experimental observations. Sustained Curie temperature can be obtained by the increase of Ca concentration x, while the transition temperatures from tetragonal to orthorhombic phase, and further to rhombohedral phase decrease with increasing Ca content. In this work, spontaneous polarization and dielectric constant dependence on concentration are studied and the relationship between hydrostatic pressure and transition temperatures is established to pave the way for the generation of temperature-concentration-pressure phase diagram.

The objective of this study is to determine whether the oxidation of Alloys 600 and 690 in supercritical water occurs by the same mechanism in subcritical water. Coupons of Alloys 690 and 600 were exposed to hydrogenated subcritical and supercritical water from 633 K to 673 K (360 °C to 400 °C) and the oxidation behavior was observed. By all measures of oxide character and behavior, the oxidation process is the same above and below the supercritical line. Similar oxide morphologies, structures, and chemistries were observed for each alloy across the critical point, indicating that the oxidation mechanism is the same in both subcritical and supercritical water. Oxidation results in a multi-layer oxide structure composed of particles of NiO and NiFe2O4 formed by precipitation on the outer surface and a chromium-rich inner oxide layer formed by diffusion of oxygen to the metal-oxide interface. The inner oxide on Alloy 600 is less chromium rich than that observed on Alloy 690 and is accompanied by preferential oxidation of grain boundaries. The inner oxide on Alloy 690 initially forms by internal oxidation before a protective layer of chromium-rich MO is formed with Cr2O3 at the metal-oxide interface. Grain boundaries in Alloy 690 act as fast diffusion paths for chromium that forms a protective Cr2O3 layer at the surface, preventing grain boundary oxidation from occurring.

A multi-scale theoretical model is performed to investigate magnetic field-induced metamagnetic martensite transition in NiCoMnIn alloys. First, the total energy is calculated to demonstrate antiferromagnetic-ferromagnetic transition from first principle calculation. Second, the transition temperature from antiferromagnetic to ferromagnetic can be tuned by the external magnetic field and hydrostatic pressure in thermodynamic calculation, which is consistent with experimental results. Third, phase field simulation found that martensite variant boundaries are superposed with the 90° antiferromagnetic magnetic domain walls, revealing magneto-structural coupling between structural and magnetic domain structures. It is demonstrated that this multi-scale model is very effective for describing antiferromagnetic-ferromagnetic accompanied with martensite-austenite transitions with magnetostructural coupling.

The environmental degradation of intermediate heat exchanger (IHX) materials in impure helium has been identified as an area with major ramifications on the design of very high-temperature reactors (VHTR). It has been reported that in some helium environments, non-ductile failure is a significant failure mode for Alloy 617 with long-term elevated-temperature service. Non-ductile failure of intermediate exchangers can result in catastrophic consequences; unfortunately, the knowledge of creep crack initiation and creep crack growth (CCG) in candidate alloys is limited. Current codes and code cases for the candidate alloys do not provide specific guidelines for effects of impure helium on the high-temperature behavior. The work reported here explores creep crack growth characterization of Alloy 617 and Alloy 800H at elevated temperatures in air and in impure helium environments, providing information on the reliability of these alloys in VHTR for long-term service. Alloy 617 was found to exhibit superior CCG resistance compared to Alloy 800H. For Alloy 617 tested at 973 K (700 °C), a notable increase in the resistance to crack growth was measured in air compared to that measured in the helium environment; CCG results for Alloy 800H suggest that air and helium environments produce similar behavior. Testing of grain boundary-engineered (GBE) Alloy 617 samples revealed that, although the technique produces superior mechanical properties in many respects, the GBE samples exhibited inferior resistance to creep crack growth compared to the other Alloy 617 samples tested under similar conditions. Grain size is noted as a confounding factor in creep crack growth resistance.

Laser surface treatment of amorphous Ti-Al-C (50:25:25 at.%) coating deposited on Zircaloy-4 substrate by dc magnetron sputtering was parametrically investigated as a function of surface temperature and dwell time. The as-deposited coating was transformed to crystalline Ti 2 AlC without significant phase alteration of Zircaloy-4 substrate under optimized conditions (900 °C for 3 s). Thermal analysis via commercial finite element software was applied to guide the selection of parameters for laser surface treatment. Coating performance was evaluated with wear and scratch tests as well as high temperature steam oxidation tests. Although laser treatment led to the formation of microcracks, it was noted to improve the mechanical integrity of the coatings and the oxidation tests indicated the protective nature of the as-deposited and laser-annealed coatings. The oxide particulate morphology and size formed during the steam oxidation tests varied dramatically between the as-deposited and laser-annealed coatings.

The oxides formed on the surface of the alloy 690 in hydrogenated supercritical water at 400 °C for 1000 h were investigated using scanning electron microscopy, transmission electron microscopy, scanning transmission electron microscopy and energy-dispersive X-ray spectroscopy. The oxides on the surface of the alloy 690 exhibited multi-layer structure: an outer layer consisted of granular crystallites (NiO and NiFe2O4) and a compact inner layer (spinel and Cr2O3). Chemical analysis indicated that the outer layer was enriched in nickel but depleted in chromium, whereas the inner layer was enriched in chromium and iron but depleted in nickel. The inner layer was also characterized as layered structure by Fe-rich spinel on top of continuous Cr2O3 layer. Besides, Cr2O3 nodules were readily observed at the oxides/alloy interface.

A phase-field model is developed to elucidate the process of polarization switching in BiFeO3 thin film. The results demonstrated an energy-favorable mechanism for domain switching path and revealed possible ferroelectric domain switching modes. It is shown that 71° switching is dominant among the three possible switching paths, namely 71°, 109° and 180° switching. This might provide significant references for the application of ferroelectric materials under electric fields.

The nuclear receptor corepressor (N-CoR) is involved in the regulation of diverse transcription factors. We previously found that N-CoR could regulate adipogenic differentiation of rat mesenchymal stem cells (MSCs), but whether it modulated osteogenic differentiation of this type of cells was uncertain. Therefore, in the present study, we investigated the effect and mechanism of N-CoR on osteogenic differentiation of rat MSCs. The results showed that MSCs cultured in osteogenic medium successfully differentiated into osteogenic cells. Overexpression of N-CoR decreased cell proliferation, alkaline phosphatase (ALP) activity, calcium accumulation, mRNA expression of genes including bone sialoprotein (BSP), osteocalcin (OCN), osteopontin (OPN), Osterix and Runx2, and protein expression of phosphor-Akt (pAkt). Conversely, knocking down cellular N-CoR by small interfering RNA (siRNA) promoted pAkt activity and cell differentiation. Overexpression or knockdown of N-CoR had no significant influences on the protein expression of pyruvate dehydrogenase kinase isozyme 1 (PDK1), phosphatidylinositol 3-kinase (PI3K) and total Akt, indicating that N-CoR regulated the changes in the PI3K/Akt signaling pathway by targeting pAkt. To further prove the function of the PI3K/Akt signaling in N-CoR-regulated osteogenic differentiation, we used the PI3K inhibitor (LY294002) to block the activation of the PI3K/Akt pathway and found that overexpression of N-CoR showed no effects on ALP activity, calcium level and mRNA expression of BSP, osteocalcin OCN, OPN, Osterix and Runx2 in rat MSCs following the inhibition of the PI3K/Akt pathway. These findings suggest that N-CoR regulates osteogenic differentiation of rat MSCs through suppression of the PI3K/Akt signaling pathway. Key words : N-CoR; MSCs; osteogenic differentiation; PI3K; Akt Received: September 1, 2015; Revised: October 16, 2015; Accepted: October 21, 2015; Published online: April 27, 2016

Corrosion testing of UNS N10003 in molten fluoride salt was performed in purified molten 27LiF-BeF2 (66–34 mol%) (FLiBe) salt at 700°C for 1,000 h, in pure nickel and graphite capsules. In the nickel capsule tests, the near-surface region of the alloy exhibited an approximately 200 nm porous structure, an approximately 3.5 μm chromium-depleted region, and MoSi2 precipitates. In the tests performed in graphite capsules, the alloy samples gained weight because of the formation of a variety of Cr3C2, Cr7C3, Mo2C, and Cr23C6 carbide phases on the surface and in the subsurface regions of the alloy. A Cr-depleted region was observed in the near-surface region where Mo thermally diffused toward either the surface or the grain boundary, which induced an approximately 1.4 μm Ni3Fe alloy layer in this region. The carbide-containing layer extended to approximately 7 μm underneath the Ni3Fe layer. The presence of graphite dramatically changes the mechanisms of corrosion attack in UNS N10003 in molten FLiBe salt. In t...

A phase-field approach to the analysis of the thickness effects in electric-field-induced domain switching in BiFeO3 thin films has been formulated. Time evolutions of domain switching percentage for films with different thicknesses were explored to reveal the primary switching path and its dependence on film thickness. In addition, hysteresis loop for these films were calculated to obtain their coercive fields. Results show a nonlinear thickness dependence of coercive field for ultrathin films. A parametric study of the interactions between film thickness, coercive field, current-voltage (I-V) response, and polarization switching behavior is herein discussed, which could provide physical insights into materials engineering.

In support of structural material development for the fluoride-salt-cooled high-temperature reactor (FHR), corrosion tests of 316 stainless steel were performed in the potential primary coolant, molten Li2BeF4 (FLiBe) at 700 °C for an exposure duration up to 3000 h. Tests were performed in both 316 stainless steel and graphite capsules. Corrosion in both capsule materials occurred by the dissolution of chromium from the stainless steel into the salt which led to the depletion of chromium predominantly along the grain boundaries of the test samples. The samples tested in graphite capsules showed a factor of two greater depth of corrosion attack as measured in terms of chromium depletion, compared to those tested in 316 stainless steel capsules. The samples tested in graphite capsules showed the formation of Cr7C3 particulate phases throughout the depth of the corrosion layer. Samples tested in both types of capsule materials showed the formation of MoSi2 phase due to increased activity of Mo and Si as a result of Cr depletion, and furthermore corrosion promoted the formation of a α-ferrite phase in the near-surface regions of the 316 stainless steel. Based on the corrosion tests, the corrosion attack depth in FLiBe salt was predicted as 17.1 μm/year and 31.2 μm/year for 316 stainless steel tested in 316 stainless steel and in graphite capsules respectively. It is in an acceptable range compared to the Hastelloy-N corrosion in the Molten Salt Reactor Experiment (MSRE) fuel salt.

Due to their combination of high-temperature coated-particle fuel, molten salt coolant and related materials requirements, fluoride-salt-cooled, high-temperature reactors (FHRs) exhibit different thermal hydraulic, neutronic and structural mechanics phenomena compared to conventional and more extensively studied other advanced nuclear reactor concepts. This paper highlights key phenomena unique to FHRs, and reviews general issues for developing, verifying, and validating evaluation models for FHR technology that may apply to other advanced reactors. System response codes that are appropriate to predict the behavior of FHRs under steady-state operation and licensing basis events are identified, along with experimental data needs to validate these codes. FHR materials requirements are highlighted, and the missions and licensing program for an FHR test reactor, providing ultimate validation data and proof of concept before a commercial prototype is built, are presented. This review draws upon information compiled in a series of four white papers based on FHR experts workshops held in 2012 in the U.S.

Investigating creep crack growth under extreme environmental conditions is a challenging yet essential undertaking for the assessment of structural lifetimes of critical components subjected to extreme working conditions for long periods of time. For example, there is currently a need to evaluate structural materials for Next Generation Nuclear Plants (NGNPs) which will operate very high temperature helium-cooled reactors (VHTRs) for generating electricity and use by-product process heat for applications such as hydrogen production and desalination. The primary helium coolant is expected to operate at temperatures at or above 750 °C. In order to evaluate candidate materials for the intermediate heat exchangers, such as Inconel 617 and Alloy 800H, we have developed a creep crack growth (CCG) test apparatus which was designed to test compact tension specimens at temperatures up to 850 °C in controlled environments, including impure helium environments, following ASTM standard E 1457–13. Details of the design of the CCG apparatus and representative results are presented.

A dynamic beryllium reference electrode has been developed for in situ electrochemistry studies of molten LiF-BeF2 (66-34 mol%) (FLiBe) salt which is being considered as the primary coolant for the fluoride salt-cooled high temperature reactor (FHR). Measurement and control of the salt redox potential can mitigate corrosion which is an important challenge in high temperature molten fluoride salts. This three electrode probe has demonstrated good reproducibility in the measurement of the salt’s redox potential with an error of ±4 mV at 500 °C. The response of the probe to changes in salt chemistry was investigated by the intentional additions of fluorides of nickel, iron, and chromium, which are corrosion products of common structural materials. The equilibrium potentials of these metal impurity fluorides were measured in solutions containing approximately 250 ppm of each impurity using cyclic voltammetry. This approach is being extended to study electrochemical purification of molten FLiBe.

Emissivity measurements for candidate alloys for very high temperature reactors were carried out in a custom-built experimental facility, capable of both efficient and reliable measurements of spectral emissivities of multiple samples at high temperatures. The alloys studied include 304 and 316 austenitic stainless steels, Alloy 617, and SA508 ferritic steel. The oxidation of alloys plays an important role in dictating emissivity values. The higher chromium content of 304 and 316 austenitic stainless steels, and Alloy 617 results in an oxide layer only of sub-micron thickness even at 700 °C and consequently the emissivity of these alloys remains low. In contrast, the low alloy SA508 ferritic steel which contains no chromium develops a thicker oxide layer, and consequently exhibits higher emissivity values.

Corrosion tests were performed in steam and supercritical water at 500 °C for two ferritic–martensitic alloys: HCM12A and NF616. The corrosion kinetics for the two alloys are similar in both environments showing near cubic behavior, but the corrosion rate was significantly higher in supercritical water than in steam. Examinations of the oxide layers using scanning electron microscopy and microbeam synchrotron diffraction and fluorescence show that both alloys form two-layer oxide structures in either environment. The outer layer contains only Fe 3 O 4 , while the inner layer contains a mixture of Fe 3 O 4 and FeCr 2 O 4 . Additionally, marker experiments using a novel photolithographic deposition process show that the original water–metal interface corresponds with the outer–inner layer interface as expected. The results are discussed in light of known corrosion mechanisms.

Corrosion of PM2000 ODS steel in supercritical CO2 at 650 °C and 20 MPa for 3000 h was studied. The corrosion performance of the alloys was evaluated by weight change measurements, and the surface oxide scale was characterized by scanning electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. PM2000 ODS steel showed significantly better corrosion resistance compared to austenitic stainless steels and nickel based alloys tested in the same conditions. The high corrosion resistance is attributed to the formation of a dense and protective aluminum-rich oxide layer on the surface. The oxide layer thickness was only about 200 nm after 3000 h exposure.

To investigate the effects of neutron irradiation on hydrogen isotope retention in tungsten, disk-type specimens of pure tungsten were irradiated in the High Flux Isotope Reactor in Oak Ridge National Laboratory followed by exposure to high flux deuterium (D) plasma in Idaho National Laboratory. The results obtained for low dose n-irradiated specimens (0.025dpa for tungsten) are reviewed in this paper. Irradiation at coolant temperature of the reactor (around 50°C) resulted in the formation of strong trapping sites for D atoms. The concentrations of D in nirradiated specimens were ranging from 0.1 to 0.4mol% after exposure to D plasma at 200 and 500°C and significantly higher than those in nonirradiated specimens because of D-trapping by radiation defects. Deep penetration of D up to a depth of 50­100µm was observed at 500°C. Release of D in subsequent thermal desorption measurements continued up to 900°C. These results were compared with the behaviour of D in ion-irradiated tungsten, and distinctive features of n-irradiation were discussed. [doi:10.2320/matertrans.MG201204]

Mg matrix nano-composites (MMNCs), reinforced with 1 wt% SiC nanoparticles, were cast by ultrasonic cavitation-based dispersion methods. Microstructural analyses of as cast specimens were conducted to characterize the grain size, shape and distribution, SiC nanoparticle size and nanoparticle-matrix interface. Average grain size for the composite specimens was 72 μm compared to 181 μm for pure Mg samples. The average SiC nanoparticle size was 66 nm. TEM studies showed good local dispersion of SiC nanoparticles, with only a few small largely spaced agglomerates. HRTEM showed a clean interface between SiC nanoparticles and the Mg matrix. The yield strength of Mg-1 wt% SiC nanocomposites was 67 MPa which showed improvement from 47 MPa for the pure Mg samples. This extra strengthening is due to Orowan and Hall–Petch effects.

Heat dissipation by radiation is an important consideration in VHTR components, particularly the reactor pressure vessel (RPV), because of the fourth power temperature dependence of radiated heat. Since emissivity is the material property that dictates the ability to radiate heat, measurements of emissivities of materials that are being specifically considered for the construction of VHTR become important. Emissivity is a surface phenomenon and therefore compositional, structural, and topographical changes that occur at the surfaces of these materials as a result of their interactions with the environment at high temperatures will alter their emissivities. With this background, an experimental system for the measurement of spectral emissivity has been designed and constructed. The system has been calibrated in conformance with U.S. DoE quality assurance standards using inert ceramic materials, boron nitride, silicon carbide, and aluminum oxide. The results of high temperature emissivity measurements of potential VHTR materials such as ferritic steels SA 508, T22, T91 and austenitic alloys IN 800H, Haynes 230, IN 617, and 316 stainless steel have been presented.

Previous studies have revealed that uncontrollable stress can impair the synaptic plasticity and firing property of hippocampal neurons, which influenced various hippocampal-dependent tasks including memory, cognition, behavior, and mood. In this work, we had investigated the effects and mechanisms of the Chinese herbal medicine Xiao Yao San (XYS) against corticosterone-induced stress injury in primary hippocampal neurons (PHN) cells. We found that XYS and RU38486 could increase cell viabilities and decrease cell apoptosis by MTT, immunofluorescence, and flow cytometry assays. In addition, we observed that XYS notably inhibited the nuclear translocation of GR and upregulated the mRNA and protein expressions levels of Caveolin-1, GR, BDNF, TrkB, and FKBP4. However, XYS downregulated the FKBP51 expressions. Furthermore, the results of the electrophoretic mobility shift assay (EMSA) and double luciferase reporter gene detection indicated that FKBP4 promotes the transcriptional activity of GR reaction element (GRE) by binding with GR, and FKBP51 processed the opposite action. Thein vivoexperiment also proved the functions of XYS. These results suggested that XYS showed an efficient neuroprotection against corticosterone-induced stress injury in PHN cells by upregulating GRE transcriptional activity, which should be developed as a potential candidate for treating stress injury in the future.

The susceptibility of binary Mg-Al alloys in permanent mold casting was tested, including Mg-0.25Al, Mg-0.6Al, Mg-1Al, Mg-2Al, Mg-4Al and Mg-8Al (all in wt %). A steel mold was used for constrained rod casting (CRC), in which rods of various lengths were cast with sudden enlargement at both ends of each rod to prevent it from free contraction during solidification and thus induce hot cracking. The cooling rate near the location of cracking was measured. The hot cracking susceptibility was evaluated based on the widths and locations of the cracks observed. The curve of crack susceptibility vs. Al content was determined and compared with previous curves based on ring casting in steel molds and constrained rod casting in sand molds. The Scheil model of solidification was used to calculate the curves of temperature vs. fraction solid (T-fS) of the alloys. The crack susceptibility curve based on a simplified hot cracking criterion and the T-fS and cooling curves was compared with that based on CRC.