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Integration of high ceramic yield, low shrinkage and excellent fracture toughness in polymer-derived ceramics (PDCs) is challenging. Highly cross-linked polycarbosilane-vinyltriethoxysilane-graphene oxide (PCS-VTES-GO, PVG) precursors spontaneously interact with dense high-strength SiC(rGO)p fillers for abundant Si-dangling bonds at their interfaces. Herein, an ingenious strategy via re-pyrolysis process of ball-milling-induced SiC(rGO)p/PVG blends is proposed to fabricate 3D-SiC(rGO)px PDCs. The in-situ formed innovative three-dimensional (3D) honeycomb cellular net-like structure, with dense β-SiC(SiO2)/SiOxCy/Cfree(rGO) framework providing high strength while tiny micro-sized pores relaxing stress at the tip, effectively improves molding process, ceramic yield and mechanical properties of PDCs. Particularly, lightweight 3D-SiC(rGO)p0.6 PDCs display dense surface, satisfactory hardness (3.96 GPa) and excellent fracture toughness (3.21 MPa m1/2), especially high ceramic yield (94.49%) and low linear shrinkage (5.00%), realizing outstanding values ever reported for PDCs to the best of our knowledge. During re-pyrolysis process, they have struck perfect balance and achieved a combination of equal volume of inwardly shrinking PVG precursors and outwardly expanding SiC(rGO)p fillers. For the first time, such synergistic effects of flexible PVG with rigid SiC(rGO)p in this way pave a practical route toward reliable mass-produced 3D-SiC(rGO)px PDCs with potential applications in emerging aerospace propulsion components.

Helicobacter pylori (H. pylori), a gram-negative bacterial microbiological carcinogen, has been identified as the leading jeopardy feature for developing human gastric cancer (GC). As a result, inhibiting H. pylori growth has been identified as an effective and critical technique for preventing GC development. In this study, geraniol inhibits H. pylori-induced gastric carcinogen signalling in human gastric epithelial cells (GES-1). Geraniol prevents cytotoxicity, ROS and apoptosis in H. pylori-induced GES-1 cells. Furthermore, geraniol protects against H. -induced antioxidant depletion caused by malondialdehyde, damage of reactive DNA and nuclear fragmentation. Geraniol significantly reduced the expression of phosphorylated mitogen activated protein kinases (MAPKs) proteins such as p38 MAPK, extracellular signal-regulated kinase-1 (ERK1), c-Jun N-terminal kinase (c-JNK), tumour necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), and cyclooxygenase-2 (COX-2) in GES-1 infected with H. pylori. Furthermore, geraniol increased the antioxidant protein peroxiredoxin-1 (Prdx-1) in H. pylori-infected cells. Geraniol thus protects H. pylori-concomitant infection, and its resistance may be a possible method in preventing gastric cancer caused by H. pylori.

This paper presents recent progress of the development and implementation of the integral transport variational nodal method (VNM) to the neutronics modelling of hexagonal geometry nuclear reactors. In this study, the three-dimensional multi-group neutron transport equation is solved with the variational nodal method utilizing an integral form of the with-in node angular flux distribution to generate response matrices more efficiently. The angular flux distributions on hexagonal nodal interfaces are approximated with even-parity spherical harmonics. The quasi-reflected interface condition (QRIC) method is employed to reduce the number of interfacial angular terms to save computational costs. Parallelization algorithms are accounted to accelerate the response matrix formation process. The newly-implemented methods are examined against the TAKEDA-4 benchmark cases, presenting superior accuracy and efficiency than the standard VNM approach. With the P7 angular approximation, the joint performance of the integral method and the QRIC method yields a remarkable computational time gain of 33.0. Furthermore, an 11-core parallelization to the response matrix formation process results in another 88% reduction in the total computation time.

The enhanced thermal conductivity oxide (ECO) nuclear fuel with BeO is analyzed from the aspect of neutronics. The Westinghouse 17 × 17 pressurized water reactor lattice model is selected as the reference and the influence on the neutronic features of different volume fractions of BeO is investigated by Monte Carlo depletion code Serpent. Results from criticality calculation of fresh fuel and depletion calculation show that increasing the fraction of BeO in the fuel will lead to more penalty on reactivity caused by extra neutron capture while the increasing moderating effect of BeO will increase the reactivity provided by the fuel. The two opposite effects compete with each other to decide the final impact the cycle length. As a result, different amount of enrichment of 235U is needed to maintain the reactivity evaluated in different models. The moderating effect leads to the softening of the spectrum and less accumulation of 239Pu when adding more BeO in the fuel. From the investigation of the radial profile, the spatially self-shielding effect decreased with the increasing of the volume fraction of BeO. Reactivity perturbation analysis show that adding BeO in the fuel causes the moderator coefficient to become less negative, which should be a concern for the reactor safety. In the analysis of the leading assembly with several standard UO2 fuel replaced with UO2-BeO, the pin power distributions of leading assemblies show the power defect at the position of the UO2-BeO fuel.

A concept of molten salt fast reactor (MSFR) was proposed in EVOL to burn transuranium element discharged from pressurized water reactors. MSFR is featured by fast spectrum and using liquid fuel salt containing UF 4 or ThF 4 . Some issues are presented, for instance, global material arrangement affects the local neutron spectrum due to long neutron free path, and fluoride salt (LiF-BeF 2 ) has nonnegligible thermal neutron scattering effect. Thus, lattice code prepared for thermal-spectrum reactor is not suitable for MSFR calculation. In this study, “two-step” calculation scheme combining Monte Carlo method and deterministic method was prepared for MSFR calculation. A tool named TRANS was developed to transfer tally data from an open source Monte Carlo code OpenMC into few-group homogenized cross-sections, and one benchmark based on pressurized water reactor and two types of model based on MSFR were used for verification. Besides, the applicability of few-group parameters generated by different model to MSFR whole-core calculation was analyzed. Finally, MSFR neutronics characteristics at steady-state were calculated using MOREL. The results show that the few-group parameters generated by one-dimension (1D) and two-dimension (2D) model are correct, and it is feasible to use OpenMC to generate few-group parameters. In case of 1D homogenization model, few-group parameters by 1D model (b) can give more accurate results both for eigenvalue and flux distribution. In MSFR whole-core calculation, using few-group cross-sections generated by 2D model has better accuracy in flux distribution, however, using few-group cross-sections generated by 1D model has better accuracy in k eff calculation. Moreover, the neutronics parameters of MSFR calculated by MOREL code agree well with that by other institutes.

High Flux Engineering Test Reactor (HFETR) focuses on the irradiation test of reactor fuel elements, thus the accurate determination of power or flux distribution becomes important. Since HFETR contains complex geometry assembly and different types of irradiation channels, the traditional simulation methods such as Monte Carlo method and deterministic method based on rectangle and hexagonal mesh are not applicable in taking into account calculation accuracy and efficiency. In this study, based on “two-step” calculation scheme, a fuel management code named TRACS was developed. Homogenization of few-group cross-sections was performed by KYLIN-II lattice code, and reactor core calculation was performed by unstructured-mesh variational nodal method. Criticality position of control rod searching adopts difference method, and micro-depletion calculation is performed by solving microscopic burnup equation using an open source matrix exponential solver EXPOKIT of Chebyshev rational approximation method. Finally, two benchmarks of HFETR sample model with different irradiation channels were used to verify TRACS code, and the results by Monte Carlo code OpenMC serve as reference. The comparison results show that the keff error is less than 300 pcm for both two cases, and the relative power error of nearly all the fuel assembly and regions in irradiation assembly at both BOL and EOL stay below 5%, and the critical positions of control rods between TRACS and OpenMC during reactor operation are nearly the same. Overall, TRACS agrees well with OpenMC, and it can be used for fuel management calculation of HFETR with complex geometrical irradiation channel.

Molten salt reactors (MSRs) are selected as one of six generation-IV nuclear power systems due to its remarkable advantages in terms of inherent safety, nuclear non-proliferation and economy. Liquid fuel makes the neutronics and thermal-hydraulics characteristics of MSRs different from those of conventional solid fuel reactors. In this study, transients perturbed by control rod ejection, local perturbation and over feeding U235 were analyzed for a graphite-moderated MSR based on a 3D coupled neutronics/thermal hydraulics code MOREL2.0. The effective delayed neutron fraction decreased with the rise of fuel mass flow. The core power changed more fiercely and even occurred supercritical phenomenon for larger fuel mass flow when the same reactivity was introduced. Local blockage introduced negative reactivity, and MSR maintained a safety state. While local overcooling resulted in positive reactivity introduction, and core power increased first then tended to be stable due to the negative temperature feedback. Furthermore, the response of core power at the transient of over feeding fissile isotopes was simulated. Those numerical results provide valuable information for the research and design of this new generation reactor.

Angiopoietin like 4 (ANGPTL4) has been proved to play an important role in lipid and glucose metabolism disorders and related cardiovascular diseases, but its role in the formation of cirrhosis still needs to be further explored. Therefore, the aim of this study was to investigate the role of ANGPTL4 in the development of liver cirrhosis and its mechanism, as well as its effect on Kupffer cell polarization and hepatic stellate cell activation. The ELISA and RT-qPCR assay were used to detect the content of ANGPTL4 in serum and mRNA expression in cells and tissues respectively. The expression of ANGPTL4, Arg1 and Mrc2 in Kupffer cells was measured by Western blot. The percentage of CD163+ and CD206+ cells was measured by flow cytometry. Mice cirrhosis model was established, and the expression of ANGPTL4 was interfered by injecting sh-ANGPTL4 lentiviral vector into caudal vein. The results revealed that ANGPTL4 was significantly up-regulated in liver cirrhosis patients and HBV induced liver injury cell models. Further studies found that interference with ANGPTL4 regulated CD163 and inhibited the polarization and proinflammatory effects of KCs，as well as inhibited the activation of hepatic stellate cells (HSCs) and fibrosis. More importantly, Interference with ANGPTL4 inhibits the progression of liver cirrhosis in mice. What's more, TLR4/NF-κB pathway was involved in the molecular mechanism of ANGPTL4 on Kupffer cells and hepatic stellate cells. It is suggested that the mechanism of sh-ANGPTL4 suppressing the polarization of KCs and the activation of hepatic stellate cells (HSCs) is to regulate the TLR4/NF-κB signaling pathways.

Due to lack of effective biomarkers for early diagnosis, most patients are diagnosed with advanced gastric cancer and have lower survival rates. 5-Fluorouracil (5-FU) is one of commonly used drugs for chemotherapy of gastric cancer, but drug resistance limits the wide application of agents. Retinoblastoma tumor suppressor gene 1 (RB1) is a key regulator in the progression of various human cancers, including gastric cancer. However, the effects of RB1 on chemosensitivity and the underlying mechanisms in gastric cancer (GC) are not clear. In this study, expressions of RB1 in GC cell lines were evaluated by RT-qPCR and western blot assay. CCK-8 was applied to examine the effect of 5-FU on cell viability. Meanwhile, IC50 values were calculated. The drug-resistance protein MDR1 and autophagy-related proteins were detected by western blot assay. Flow cytometry was used to detect cell cycle. The results showed that RB1 expressions were downregulated in GC cell lines and had significant differences between 5-FU resistance cell lines (SNU-620/5-FU and NUGC-3/5-FU) and non-resistance cell lines (SNU-620 and NUGC-3). Overexpression of RB1 enhanced 5-FU sensitivity of GC cells and caused cell cycle arrest in the S phase. Meanwhile, autophagy-related proteins were downregulated. Mechanistically, SDF-1/CXCR4 participated in the regulation of RB1 on cell autophagy. Autophagy activator, SDF-1 treatment and CXCR4 activation reversed the promoted effects of RB1 on 5-FU sensitivity in GC cells. In conclusion, our data revealed that RB1 was downregulated in GC cell lines. RB1 overexpression enhanced 5-FU chemosensitivity in GC cells by regulating cell autophagy via SDF-1/CXCR4 pathway. RB1 might serve as a promising therapeutic target of GC.

In order to study the thermal and hydraulic characteristics of nuclear reactors under ocean conditions and meet the urgent needs of the design of floating nuclear power plants, the crossflow and heat transfer characteristics of rod bundle with the spacer grid under rolling conditions are studied by using computational fluid dynamics (CFD) code. Firstly, revise and verify CFD codes suitable for rolling conditions. According to CFD results, the influence of heat flux on heat transfer coefficient is greater than that of pressure drops under this condition. And with the spacer grid, the total pressure drop between inlet and outlet is higher. Furthermore, the heat transfer coefficient is also higher due to the mixing effect of spacer grid. Under periodic inlet velocity, the fluctuation amplitude of total pressure, the temperature difference between inlet and outlet and heat transfer coefficient is increased obviously with the spacer grid. Under the condition of nonuniform heat flux, the variation law of crossflow with rolling motion will become more obvious and the spacer grid can enhance the crossflow mixing and improve the heat transfer capacity of the fluid under rolling conditions.

An ingenious strategy to prepare in-situ formed SiC(Al, rGO) bulk polymer-derived ceramics (PDCs) from re-pyrolyzing SiC(Al, rGO)p/polyaluminocarbosilane-vinyltriethoxysilane-graphene oxide (PACS-VTES-GO, PAVG) blends is highlighted. Flexible PAVG modified by Al with highly cross-linked structure effectively improves molecular weight and formability of precursors. Rigid SiC(Al, rGO)p fillers provide high mechanical properties owing to their unique microstructure which is consistent with SiC(Al, rGO) bulk PDCs. β-SiC nanocrystals are well dispersed in amorphous SiOxCy/Cfree, and rGO exhibits good compatibility with SiOxCy/Cfree. Besides, possible Al2O3 is beneficial to relaxing thermal stress at β-SiC nanocrystalline boundaries. Interestingly, introduction of Al could avoid coarsening of β-SiC grains to enhance elevated temperature resistance. Furthermore, effect of re-pyrolysis temperature on the formation and microstructure of SiC(Al, rGO) bulk PDCs was also investigated. Particularly, lightweight samples re-pyrolyzed at 1300 °C display optimal fracture toughness (3.32 MPa m1/2), compressive strength (177.16 MPa) and flexural strength (51.25 MPa), high ceramic yield (94.46%) and low linear shrinkage (4.38%), by far superior to those of most PDCs. As treated via precursor infiltration and pyrolysis (PIP) route and heated by butane gun flame in air, such products possess stable structures under elevated temperatures and have potential emerging uses in aerospace components.

Small specimen test technique is widely used to evaluate material creep properties for those components operated at the elevated temperatures. However, the existing small specimen test techniques cannot be well applied for small miniature tubular components well, such as steam pipe and gas turbine recuperator in aviation, due to the equivalent gauge length, specimen volume, stress analysis method and conversion relationship. In this paper, combing the advantages of three-point bending specimen with fixed constraints and small ring creep specimen, a new C-shape ring specimen with fixed constraints (CRSFC) was proposed. Based on beam bending model, the conversion relationship between CRSFC and uniaxial creep test data was established by using complementary strain energy and reference stress method. Using finite element method, conversion coefficients and stress evolution process were obtained. Then the feasibility and accuracy of the above conversion relationship were verified by carrying out four sets of CRSFC creep tests of 1.25Cr0.5MoSi at 550 °C. It can be seen that creep parameters obtained by CRSFC agree well with those from uniaxial creep test with the maximum error of 22.6%. Finally, the effects of the straight edge length, indenter radius, eccentric load and indenter-specimen surface friction coefficient on the load-point steady-state displacement rate were investigated by finite element method. The results show that the effect of the straight edge length is negligible. In order to minimize the effects of other parameters, the indenter radius 0.6 mm ≤ r ≤ 1.2 mm, eccentric displacements e ≤ 0.2 mm and friction coefficient f ≤ 0.8 are recommended in CRSFC creep test.

Failure analysis was conducted for a cracked Incoloy 800H reformer tube serviced at 580℃ in an ammonia installation based on the microstructure observation, fracture analysis, mechanical properties testing and finite element analysis. Results showed that the stress relaxation cracking (SRC) during operation was the primary cause of the repeated cracking, and the assembling malposition had a significant impact on the SRC by raising local stress. The larger the malposition was restrained, the earlier the cracking time was. A method for estimating the failure time due to malposition was proposed, which could be used to determine the malposition criteria during fabrication. In addition, the aged Incoloy 800H tube was much more sensitive to the SRC than virgin material since the ductility of the material decreased obviously after about 5 years’ service at high temperature. This work confirms that “free-stress deflection angle” method is of choice to reduce SRC in case large malposition cannot be avoided.

The combination of advancement in nuclear technology and ship engineering is a new technology of nuclear application which can not only marine capability and provide power for remote islands, but also help solve the practical issues of high cost, high pollution and high pressure in cutting down emissions in the petroleum exploitation field. The CFD analysis in this paper focuses on the exploration of single-phase natural circulation flow and heat transfer characteristics for rod bundle under rolling conditions. The rolling version CFD tool is developed and compared with the calculated results by system code. The natural circulation system which consists of a 2 by 2 subchannel is established. This paper mainly focuses on the effect of different rolling parameters on natural circulation flow and heat transfer characteristics for rod bundle loop under rolling motion. The thermal–hydraulic performance varies periodically under rolling motion. The variation period equals to rolling period. The stronger the rolling intensity is, the greater the fluctuations of different thermal–hydraulic parameters are. The average values of mass flux and heating section temperature difference under rolling conditions are lower than those under non-rolling conditions, proving that rolling motion may enhance heat transfer. Meanwhile, the inlet temperature of heating section under rolling conditions is lower compared with that under non-rolling conditions. With increasing rolling intensity, the effect of heat transfer enhancement is greater.

Adopting liquid fuel and on-line reprocessing scenario are the unique features of molten salt reactor (MSR). Considering lattice code for thermal reactor is not suitable for MSR calculation, batch-wise fuel salt reprocessing scheme and “two-step” deterministic calculations cause some approximations in simulation of MSR on-line continuous fuel reprocessing, this study focuses on the development of a direct calculation method for MSR fuel cycle simulation based on an open source Monte Carlo code OpenMC. A fictitious decay constant and an external source term were introduced into traditional burnup equation for accurate simulation of on-line fuel reprocessing. Finally, a MSR fuel cycle simulation code OpenMCB-MSR was developed by coupling OpenMC and burnup code with Python script. Two pressurized water reactor (PWR) pin cell benchmarks without considering fuel on-line reprocessing, and one actual MSFR fuel cycle benchmark considering fuel on-line reprocessing were used for verification of OpenMCB-MSR. By comparison with reference results, the maximum differences of kinf calculated by OpenMCB-MSR are no more than 400 pcm both for two PWR pin cell benchmarks. Moreover, apart from isotopes with small absolute nuclide number density, all the other isotopes' nuclide number densities show a difference of less than 10%. For MSFR benchmark, the reactivity coefficients, isotope mass evolutions during fuel cycle process, mass evolution of fission products in core and breeding ratio calculated by OpenMCB-MSR show a good agreement with reference results. At equilibrium state, apart from isotopes with very small absolute mass, the differences of other isotopes' mass are no more than 5.0% in comparison with reference results. Benchmark verification results indicate that the method of MSR fuel cycle simulation based on OpenMC code is correct, and OpenMCB-MSR has capability of MSR fuel cycle analysis.

In this paper the creep parameters for a Norton law material are determined from the creep bending tests data by an elliptical arc shape specimen. According to the ideal time-dependent beam theory, the creep coefficient B and creep exponent are derived as a function of the applied load and displacement rate. Finite element simulations of the elliptical arc specimen bending creep are also carried out to validate the feasibility and accuracy of the proposed approach. Our work will contribute to a better understanding to derive creep parameters from creep bending test and extend its application for the milli/micro scale miniature specimen.

We previously showed that Rig-G, an antiproliferative protein induced by interferon, can sequester CSN5 protein in the cytoplasm. Here, we report that Rig-G can destroy the functions of CSN5-containing COP9 signalosome (CSN), a highly conserved multiprotein complex implicated in protein deneddylation, deubiquitination, and phosphorylation. By damaging integrity and stability of the CSN complex, Rig-G can dramatically reduce the cellular content of CSN complex and inhibit its regulatory roles in assembly and activation of cullin-RING ubiquitin E3 ligases (CRL). Furthermore, Rig-G can cause excessive activation of CRL through inhibition of CSN-mediated deneddylation, largely decreasing protein levels of Cul1 and βTrCP, two important subunits of SCF (Skp1-Cul1-F-box protein)-E3 ligase. Rig-G can also attenuate the ability of CSN to recruit USP15 and impair CSN-associated deubiquitination. Increased autoubiquitination of βTrCP and concomitant accumulation of target substrates (such as IκBα) are observed in Rig-G-expressing cells. Taken together, our findings reveal for the first time the negative regulation of Rig-G on SCF-E3 ligase activities through disrupting CSN complex, not only contributing to further investigation on biological functions of Rig-G, but also leading to better understanding of the CSN complex as a potential target in tumor diagnosis and treatment.

In this paper, some new oscillation criteria are obtained for second order elliptic differential equations with damping of the form ∇ ⋅ ( A ( x ) ∇ y ) + B T ( x ) ∇ y + q ( x ) f ( y ) = 0 , x ∈ Ω , where Ω is an exterior domain in R N . These criteria are different from most known ones in the sense that they are based on a class of new functions of the form Φ ( r , s , l ) defined in the sequel.

This paper is concerned with oscillation of second-order nonlinear neutral dynamic equations on time scales with a variable delay. By using the generalized Riccati technique and integral averaging technique, new oscillation criteria are obtained for all solutions of the equation. Some results extend known results for difference equations when the time scale is the set Z + of positive integers and for differential equations when the time scale is R . Several examples are given to illustrate the results of the paper.

In this paper, we first establish some differential inequalities and then some Sturm comparison theorems are derived for the second order nonlinear differential equations. Also, our results generalize some classical Sturm comparison theorems.

Some oscillation criteria for the second order neutral nonlinear differential equation[y(t)+p(t)y(@s(t))]^''[email protected]?"i"="1^nq"i(t)f"i(y(@t"i(t)))=0,t>=t"0are established. New oscillation criteria are different from most known ones in the sense that they are based on the information only on a sequence of subintervals of [t"0,~), rather than on the whole half-line. Our results are more natural according to the Sturm Separation Theorem.

Chronoamperometry based on the ‘diffusion’ layer concept of the convective system was used to assay the activity of mitochondrial malate dehydrogenase (MDH). When the enzyme-catalysed reaction was initiated by adding the enzyme MDH into a well-stirred nicotinamide adenine dinucleotide (NADH, coenzyme) solution, the enzyme activity could be indicated by the continuous in-situ decrease in the limiting steady-state oxidation current of NADH. The effects of some lanthanide ions on the MDH activity were monitored. The La 3+ , Ce 3+ and Eu 3+ ions could activate markedly the enzyme MDH as the concentrations were lower. The activation mechanism would be that the lanthanide ions could interrupt the binding of NAD + to MDH by combining preferentially to NAD + . This mechanism was proposed on the basis of voltammetric and Raman spectroscopic studies.

A trace of 5, 10, 15, 20-tetraphenyl-21H, 23H-porphyrin (H 2 TPP) was mechanically transferred to the surface of a paraffin-impregnated graphite electrode and associated with copper ions in an aqueous media by electrochemistry. Under different electrochemical conditions, two cases of surface associations of H 2 TPP with copper ions are obtained. The formations were characterized by the voltammetry of the immobilized microparticles. According to the different voltammetric behaviors of the two cases of the in situ formed copper porphyrins, the different association mechanisms of the two cases of copper porphyrins were elucidated.

A chronoamperometric method based on the ‘diffusion’ layer concept of the convective system was used to assay the glutamate dehydrogenase (GLDH) activity. Once the reaction was initiated by adding the enzyme GLDH into a well-stirred nicotinamide adenine dinucleotide (NADH, coenzyme) solution, the steady-state oxidation limiting current of NADH would decrease linearly in a short time. The major advantage of this method is that it directly indicates the continuous in-situ change of the coenzyme concentration, thus, the real initial reaction rate of enzyme-catalyzed reaction, V0, can be determined. Using this method, the effect of adenosine-5′-monophosphate (AMP) and adenosine-5′-diphosphate (ADP) on the GLDH activity has been monitored. The results showed that ADP and AMP could increase the activity of GLDH. This activation mechanism was proposed by the voltammetric study.

Under steady-state conditions, the current equations of the second-order EC, ECE and DISPI reactions at microdisk, microspherical and microring electrodes are derived with the aid of the concept of the reaction layer. The conditions under which these equations would be valid are also discussed. Using these equations, methods to determine the kinetic parameters for the second-order EC, ECE and DISPI reactions are presented. The reduction of 2,6-diphenyl-pyrylium cation and oxidation of triphenylamine were investigated as examples of the second-order EC and ECE reactions.