Comparison of two different laparotomy methods for modeling rabbit VX2 hepatocarcinoma

AIM:To compare two different laparotomy methods for modeling rabbit VX2 hepatocarcinoma.METHODS:Thirty New Zealand rabbits were randomly divided into two groups:A and B.Group A was assigned a traditional laparotomy method(embedding tumor fragments directly into the liver with tweezers).Group B was subjected to an improved laparotomy method(injection of tumor fragments into the liver through a 15 G syringe needle).The operation time, incision length, incision infection rate, and mortality rate were compared between the two groups after laparotomy.Magnetic resonance imaging(MRI) was performed to evaluate tumor formation rates and the characteristics of the tumors 2 wk after laparotomy.RESULTS:The mean operation times for the two groups(Group A vs Group B) were 23.2 ± 3.4 min vs 17.5 ± 2.9 min(P < 0.05); the incision length was 3.3 ± 0.5 cm vs 2.4 ± 0.6 cm(P < 0.05); and the mortality rate after 2 wk was 26.7% vs 0%(P < 0.05); all of these outcomes were significantly different between the two groups.The incision infection rates in the two groups were 6.7% vs 0%(P > 0.05), whichwere not significantly different.MRI performed after 2weeks showed that the tumor formation rates in the two groups were 90.9%vs 93.3%(P>0.05).These rates were not significantly different between the two groups.The celiac implantation rate and abdominal wall metastasis rate in the two groups were 36.4%vs 13.3%(P<0.05)and 27.2%vs 6.7%(P<0.05),respectively,which were significantly different between the two groups.CONCLUSION:The tumor formation rates were not significantly different between the two methods for modeling rabbit VX2 hepatocarcinoma.However,the improved method is recommended because it has certain advantages.

Mechanism of local solidification time variations with melt rate during vacuum arc remelting process of 8Cr4Mo4V high-strength steel

A 2D axisymmetric numerical model was established to investigate the variations of molten pool with different melt rates during the vacuum arc remelting of 8Cr4Mo4V high-strength steel,and the ingot growth was simulated by dynamic mesh techniques.The results show that as the ingot grows,the molten pool profile changes from shallow and flat to V-shaped,and both the molten pool depth and the mushy width increase.Meanwhile,the variation of both the molten pool shape and the mushy width melt rate is clarified by the thermal equilibrium analysis.As melt rate increases,both the molten pool depth and the mushy width increase.It is caused by the increment in sensible heat stored in the ingot due to the limitation of the cooling capacity of the mold.The nonlinear increment in sensible heat leads to a nonlinear increase in the mushy width.In addition,as melt rate increases,the local solidification time(LST)of ingot decreases obviously at first and then increases.When melt rate is controlled in a suitable range,LST is the lowest and the secondary dendrite arm spacing of the ingot is the smallest,which can effectively improve the compactness degree of 8Cr4Mo4V high-strength steel.

Effects of TiC on the microstructure and formation of acicular ferrite in ferritic stainless steel

The formation mechanism of acicular ferrite and its microstructural characteristics in 430 ferrite stainless steel with TiC additions were studied by theory and experiment.Using an"edge?to?edge matching"model,a 5.25 mismatch between TiC(FCC structure)and ferritic stainless steel(BCC structure)was identified,which met the mismatch requirement for the heterogeneous nucleation of 430 ferritic stainless steel.TiC was found to be an effective nucleation site for the formation of acicular ferrite in a smelting experiment,as analyzed by metallographic examination,Image-Pro Plus 6.0 analysis software,and SEM–EDS.Furthermore,small inclusions in the size of 2–4?m increased the probability of acicular ferrite nucleation,and the secondary acicular ferrite would grow sympathetically from the initial acicular ferrite to produce multi-dimensional acicular ferrites.Moreover,the addition of Ti C can increase the average microstrain and dislocation density of 430 ferrite stainless steel,as calculated by Williamson-Hall(WH)method,which could play some role in strengthening the dislocation.

Corrosion behavior of ferritic stainless steel with 15wt% chromium for the automobile exhaust system

The effect of chloride ion concentration, pH value, and grain size on the pitting corrosion resistance of a new ferritic stainless steel with 15wt% Cr was investigated using the anodic polarization method. The semiconducting properties of passive films with different chloride ion concentrations were performed using capacitance measurement and Mott-Schottky analysis methods. The aging precipitation and intergranular corrosion behavior were evaluated at 400- 900℃. It is found that the pitting potential decreases when the grain size increases. With the increase in chloride ion concentration, the doping density and the flat-bland potential increase but the thickness of the space charge layer decreases. The pitting corrosion resistance increases rapidly with the decrease in pH value. Precipitants is identified as Nb（C,N） and NbC, rather than Cr-carbide. The intergranular corrosion is attributed to the synergistic effects of Nb（C,N） and NbC precipitates and Cr segregation adjacent to the precipitates.

Industrial test of a 6-m long bearing steel ingot by electroslag remelting withdrawing process

In this study, the key technologies of a 6-m long bearing steel ingot produced by electroslag remelting withdrawing(ESRW) process, including bifilar mode supply, slag system development, and design of mold, were studied based on the laboratory research achievements. The 6-m long ingot of bearing steel GGr15 with a cross-section of 300 mm × 340 mm was produced using the ESRW process with a bifilar mode and a multi-taper T-mold in a plant. The testing results show that the melting rate using the ESRW bifilar mode technology is three times faster than traditional electroslag remelting(ESR), and the power consumption is only 1,320 k Wh per ton steel. Through testing for the chemical composition, macrostructure and inclusions of remelted ingot, it can be concluded that the ESRW bifilar mode technology not only retains the characteristics of traditional ESR, but also improves the production efficiency and reduces the cost compared to traditional ESR.

The crosstalk between enteric nervous system and immune system in intestinal development,homeostasis and diseases

The gut is the largest digestive and absorptive organ,which is essential for induction of mucosal and systemic immune responses,and maintenance of metabolic-immune homeostasis.The intestinal components contain the epithelium,stromal cells,immune cells,and enteric nervous system(ENS),as well as the outers,such as gut microbiota,metabolites,and nutrients.The dyshomeostasis of intestinal microenvironment induces abnormal intestinal development and functions,even colon diseases including dysplasia,inflammation and tumor.Several recent studies have identified that ENS plays a crucial role in maintaining the immune homeostasis of gastrointestinal(GI)microenvironment.The crosstalk between ENS and immune cells,mainly macrophages,T cells,and innate lymphoid cells(ILCs),has been found to exert important regulatory roles in intestinal tissue programming,homeostasis,function,and inflammation.In this review,we mainly summarize the critical roles of the interactions between ENS and immune cells in intestinal homeostasis during intestinal development and diseases progression,to provide theoretical bases and ideas for the exploration of immunotherapy for gastrointestinal diseases with the ENS as potential novel targets.

Mathematical Modeling of ESR Process for Hollow Ingot with Current Supplying Mould

With ificreasing demand for large cylindrical forgings, a new technology--electroslag remelting （ESR） for direct manufacture of hollow ingots rather than solid ingots has been developed. The main features of the process include a T-shaped current supplying mould （CSM）, double power supply, an ingot withdrawing system, a metal level automatic control system based on a level sensor using the electromagnetic eddy current method, and the exchange of a consumable multi-electrode. ANSYS software was used to calculate the fluid flow and heat transfer in the slag bath 1 and metal pool of this ESR hollow ingot process with its T-shaped CSM. The mathematmal model was Verified by measuring the geometry of the liquid metal pool as observed in the macrostructure of 4650 mm （external diameter）/ 4450 mm （internal diameter） hollow ingots by sulphur print method： the. observed shape and depth of the s!ag bath were consistent with the simulated results. Simulation of the ESR process can improve understanding of the process and allow better operating parameters to be selected.

An innovative method for calibrating local cooling rate in electroslag remelting of M42 high-speed steel

The determination of the local cooling rate has a great significance in optimizing the parameters of electroslag remelting(ESR)and improving the quality of the ingots.An innovative method was proposed for calibrating the local cooling rate of M42 high-speed steel(HSS)in the ESR process.After resolidification at different cooling rates under high-temperature laser confocal microscopy,the carbide network spacing of the specimen was observed using a scanning electron microscope.A functional relationship between the cooling rate and average carbide network spacing was established.The average local cooling rate of the solidification process of the M42 HSS ingot was calibrated.The results show that the higher the cool-ing rate,the smaller the network spacing of the carbides.For the steel ingot with a diameter of 360 mm,the average local cooling rate was 0.562℃/s at the surface,0.057℃/s at the position of 0.25D(where D is the diameter of the ingot),and 0.046℃/s at the center of the ingot.

Effect of atmospheric pressure on physical parameters of steels and solidification conditions during PESR process:a review

The pressurized electroslag remelting(PESR)process has a remarkable impact on manufacturing high nitrogen steels,which can alter the physical parameters of steels and solidification conditions at different atmospheric pressures.The principle and applications of the PESR process are reviewed.The effect of atmospheric pressure,including Gibbs free energy,nitrogen solubility,melting point,viscosity,diffusion coefficient,partition coefficient,and nucleation rate,is explicitly expressed by empirical knowledge and quantified by thermodynamic relationships.The variation of interfacial heat transfer coefficient is discussed at different atmospheric pressures.Furthermore,the effect of atmospheric pressure on physical parameters of steels and solidification conditions during the PESR process is still in their embryonic research stage and it is important to do further study in this research field.Finally,a general concluding remark and suggestions for future development are proposed.

m^(6)A mRNA modification potentiates Th17 functions to inflame autoimmunity

N6-methyladenosine(m^(6)A),the most common and abundant epigenetic RNA modification,governs mRNA metabolism to determine cell differentiation,proliferation and response to stimulation.m^(6)A methyltransferase METTL3 has been reported to control T cell homeostasis and sustain the suppressive function of regulatory T cells(Tregs).However,the role of m^(6)A methyltransferase in other subtypes of T cells remains unknown.T helper cells 17(Th17)play a pivotal role in host defense and autoimmunity.Here,we found that the loss of METTL3 in T cells caused serious defect of Th17 cell differentiation,and impeded the development of experimental autoimmune encephalomyelitis(EAE).We generated Mettl3f/fIl17aCre mice and observed that METTL3 deficiency in Th17 cells significantly suppressed the development of EAE and displayed less Th17 cell infiltration into central nervous system(CNS).Importantly,we demonstrated that depletion of METTL3 attenuated IL-17A and CCR5 expression by facilitating SOCS3 mRNA stability in Th17 cells,leading to disrupted Th17 cell differentiation and infiltration,and eventually attenuating the process of EAE.Collectively,our results highlight that m^(6)A modification sustains Th17 cell function,which provides new insights into the regulatory network of Th17 cells,and also implies a potential therapeutic target for Th17 cell mediated autoimmune disease.

Numerical investigation on melting characteristics of scrap with heat and mass transfers in molten steel

Herein,a numerical simulation with simultaneous heat and mass transfers is carried out to investigate the scrap melting characteristics in molten steel after model verification by published experimental data.The numerical results show that the scrap melting stages consist of the frozen shell formation stage,the frozen shell remelting stage and the parent scrap melting stage.The heat transfer coefficient and the carbon mass transfer coefficient between the scrap and the molten steel are,respectively,in the range of 4209-6249 W m^(-2) K^(-1) and 6.4×10^(-5) m s^(-1).Meanwhile,the effects of process parameters on scrap melting time were studied.An increase in the scrap preheating temperature(T_(scrap)),the molten steel temperature(T_(steel))and the carbon content of molten steel(C_(steel)),and a decrease in the scrap thickness dscrap,can reduce the frozen shell existence time,as well as the scrap melting time.On this basis,a quantitative relationship between the aforementioned process parameters and the scrap melting time is obtained to predict the formation of frozen shell(W),which provides process guidance for shortening the scrap melting time.The quantitative relationship is expressed as:lnΨ=311.32-2.34ln(T_(scrap))-39.99ln(T_(steel))-0.08ln(d_(scrap))-0.57ln(C_(steel)).

Effect of melt current on multi-physical field and heat flow distribution during ESR process based on model of dynamic formation of slag skin

A numerical model coupled with a multi-physical field based on dynamic formation of slag skin is established.After validation by comparing the experimental and simulation results of depth of metal pool,slag skin thickness and melt rate,it is utilized to investigate the effect of melt current on the coupled multi-physical field,slag skin thickness,metal pool depth and the heat flow distribution during electroslag remelting(ESR)Inconel 625 solidification process.The results showed that with the increase in the melt current,the velocities of ESR system and the temperature of metal pool increased,whereas the highest temperature of slag bath firstly decreased and then increased.With the increase in the melt current,the slag skin thickness,metal pool depth and melt rate increased.Furthermore,the characteristics of the heat flow distribution and the effect of melt current on the heat flow distribution were analysed.

RNA m^6A modification and its function in diseases

N^6-methyladenosine （m^6A） is the most common post-transcriptional RNA modification throughout the transcriptome, affecting fundamental aspects of RNA metabolism, m^6A modification could be installed by m^6A ＂writers＂ composed of core catalytic components （METTL3/METTL14/WTAP） and newly defined regulators and removed by m^6A ＂erasers＂ （FTO and ALKBH5）. The function of m^6A is executed by m^6A ＂readers＂ that bind to m^6A directly （YTH domain-containing proteins, eIF3 and IGF2BPs） or indirectly （HNRNPA2B1）. In the past few years, advances in m^6A modulators （＂writers,＂ ＂erasers,＂ and ＂readers＂） have remarkably renewed our understanding of the function and regulation of m^6A in different cells under normal or disease conditions. However, the mechanism and the regulatory network of m^6A are still largely unknown. Moreover, investigations of the m^6A physiological roles in human diseases are limited. In this review, we summarize the recent advances in m^6A research and highlight the functional relevance and importance of m^6A modification in in vitro cell lines, in physiological contexts, and in cancers.

Effect of partial replacement of carbon by nitrogen on intergranular corrosion behavior of high nitrogen martensitic stainless steels

The microstructure evolution and intergranular corrosion(IGC) behavior of high nitrogen martensitic stainless steels(MSSs) by partial replacing C by N were investigated by using microscopy, X-ray diffraction, nitric acid tests and double-loop electrochemical potentiokinetic reactivation(DL-EPR) tests. The results show that the partial replacement of C by N first reduces and then increases the size and content of precipitates in high nitrogen MSSs, and converts the dominant precipitates from M23C6 to M2N,furthermore first improves and then deteriorates the IGC resistance. The high nitrogen MSS containing medium C and N contents provides good combination of mechanical properties and IGC resistance.

Chi Phase after Short-term Aging and Corrosion Behavior in 2205 Duplex Stainless Steel

Correlation between pitting corrosion behavior and chi（ χ ）phase formed after a short-term aging（5,10 and 15 min）at 850 ℃ of 2205 duplex stainless steel（DSS）was investigated using potentiodynamic polarization tests,optical microscopy,and scanning electron microscopy equipped with energy-dispersive spectrum system.Results showed that after aging for 5min,the χ phase initially precipitated at ferrite grain boundaries,developed and then became linked with prolonging aging time.The χ phase was rich in Cr and Mo,resulting in formation of depleted zones nearby.The χ phase could reduce corrosion resistance of DSS and slightly influence its stability,but the specimens still displayed the capacity for repassivation.Some lines of evidence showed that stable pitting corrosion initiated at the boundaries of precipitates.The χ phase was selectively corroded during the first stage of corrosion and then the depleted zones nearby were attacked.In addition,the grain size and volume of precipitates also affected pit nucleation and progress,and suitable size and distribution of χ phase could aggravate pit initiation at precipitate boundaries.The χ phase with considerably low volume fraction and small size was not sensitive position for pit initiation.

Aluminum,titanium and oxygen control during electroslag remelting of stainless steel based on thermodynamic analysis

Experimental investigation and thermodynamic calculation were carried out to study the effect of slag on alloying elements during electroslag remelting with developing a thermodynamic model to control titanium and aluminum in in got.The thermodynamic model based on ion and molecule coexistence theory and conservation law of element atoms was established to analyze the change in aluminum and titanium along the height of ingot.The results show that low CaO slag is suitable for electroslag remelting of metal containing high titanium-to-aluminum ratio.As electroslag remelting process consists of slag temperature-rising and temperature-stable periods,TiO2 should be added into water-cooled copper mold during temperature-rising period in order to keep the thermodynamic equilibrium between titanium and aluminum,and the amount of TiO2 is the difference value calculated by the reaction between titanium and alumina at 1477 and 1677℃.

Influence of Austenitizing Temperature on the Microstructure and Corrosion Resistance of 55Cr18Mo1VN High-Nitrogen Plastic Mould Steel

The influence of austenitizing temperature on the microstructure and corrosion resistance of 55Cr18MolVN high-nitrogen plastic mould steel was investigated. The microstructure, elemental distribution and Cr-depleted zone of different heat-treated samples were investigated by X-ray diffraction, electron probe microanalyzer analysis, and trans- mission electron microscopy. The corrosion resistance was evaluated using electrochemical measurements, and the analysis of passive film was carded out by X-ray photoelectron spectroscopy. The results indicated that the volume fraction of precipitates decreased, and the homogeneity of elements was improved with increasing austenitizing temperature. The degree of Cr-depleted zone around coarse M23C6 was severer than that around M2N, and pitting corrosion initiated preferentially around M23C6. The corrosion resistance of the samples increased with the austenitizing temperature. With the increase in austenitizing temperature, the passive film was thickened and Cr（III）cr2O3 in the inner layer of passive film was enriched, which enhanced the corrosion resistance of the steel. The higher content of nitrogen in solid solution at higher austenitizing temperature contributed to the increased intensity of CrN and NH3, leading to the increase in pH value in the pit, and promoting the repassivation of 55Cr18Mo1N steel.

Effect of La on inclusions and fracture toughness of low-alloy ultrahigh-strength 40CrNi2Si2MoVA steel

The effect of La on inclusions and fracture toughness of 40CrNi2Si2MoVA steel was investigated via the optical microscope,scanning electron microscope,image software and electronic universal testing machine.The results reveal that the inclusions in steel without La are mainly MnS and Al_(2)O_(3)–MnS,while the inclusions in steels with La primarily contain La–O–S,La–S and other rare earth complex inclusions contain P and As.La–O–S and La–S are formed under the steelmaking temperature and act as the nucleation core of rare earth complex inclusions containing P and As.According to the segregation model,La–O–S–P–As and La–S–P–As are formed through chemical reactions during the solidification stage.As La content in steels increases from 0 to 0.032 mass%,the average spacing of inclusions is gradually increased from 5.28 to 15.91μm.The volume fraction of inclusions in steels containing less than 0.018 mass%La approaches 0.006%;however,it is significantly improved to 0.058%when La content is increased to 0.032 mass%.With the increase in La content,the fracture toughness is firstly improved from 63.1 to 80.0 MPa m^(1/2)due to the increase in average spacing of inclusions and then decreases to 69.6 MPa m^(1/2)owing to the excessive increase in volume fraction of inclusions.The optimal fracture toughness is found in 40CrNi2Si2MoVA steel with 0.018 mass%La.

Antibacterial activities of a novel Cu-bearing high-entropy alloy against multi-drug-resistant Acinetobacter baumannii and Staphylococcus aureus

Acinetobacter baumannii and methicillin-resistant Staphylococcus aureus(MRSA)are two prevalent pathogens and have developed high resistant to most antibiotics.Therefore,it is a pressing need to develop a new method to inhibit the spread of drug-resistant bacteria.Copper containing high-entropy alloy(HEA,Al0.4CoCr-CuFeNi)is a new kind of alloy material,which shows extensive antibacterial activity and mechanical properties in our previous research.This study further develops another HEA(CoCrCuFeNi)and evaluates its resistance against gram-negative A.baumannii and Gram-positive MRSA.The antibacterial tests show that the antibacterial rate of the HEA toward both bacteria reached nearly 99%,far better than the traditional copper-bearing 304 stainless steel(304 Cu-SS).The biofilm observation shows that the HEA could not only kill the planktonic bacteria,but also effectively inhibit the formation of biofilm.These data demonstrate that CoCrCuFeNi HEA possesses effective antibacterial and antibiofilm activities,making it a potential candidate for using in hospital,food industry,and domestic kitchens.

Effects of current path on structure and segregation during electroslag remelting process of Inconel 718 alloy with same power input

Current-conductive mold was recently developed to extend electroslag remelting(ESR)functions to overcome some solidification defects by changing the current path.The macrostructures,microstructures,macrosegregation,and microsegregation of the Inconel 718 ingots produced by the custom laboratory-scale ESR furnace under different current paths(the classical ESR and the single power,and two circuits ESR process with current-conductive mold(ESR-STCCM))with the same power input were compared and investigated.The results indicate that when the ingot was produced during ESR and ESR-STCCM processes,at the same power input,the pool depth was 104 and 90 mm,respectively.A flatter and shallower molten pool was obtained during ESR-STCCM process.Moreover,compared with a classical ESR ingot,the cooling rate of the centerline of ESR-STCCM ingot was increased from 12.7 to 16.7 K min^(−1).The increased cooling rates caused by decreased melting rate and thinner slag skin reduced the growth angle of columnar crystal to the vertical axis and the secondary dendrite arm spacing.Furthermore,the macrosegregation and microsegregation of segregation elements for ESR-STCCM process were dramatically reduced compared with ESR process.The average volume fraction of Laves phase was reduced from 7.39%to 6.14%,and the segregation of Nb in Laves phase was significantly reduced.