MH-STRALP:A scoring system for prognostication in patients with upper gastrointestinal bleeding

BACKGROUND Upper gastrointestinal bleeding(UGIB)is a common medical emergency and early assessment of its outcomes is vital for treatment decisions.AIM To develop a new scoring system to predict its prognosis.METHODS In this retrospective study,692 patients with UGIB were enrolled from two cen-ters and divided into a training(n=591)and a validation cohort(n=101).The clinical data were collected to develop new prognostic prediction models.The en-dpoint was compound outcome defined as(1)demand for emergency surgery or vascular intervention,(2)being transferred to the intensive care unit,or(3)death during hos-pitalization.The models’predictive ability was compared with previously esta-blished scores by receiver operating characteristic(ROC)curves.RESULTS Totally 22.2%(131/591)patients in the training cohort and 22.8%(23/101)in the validation cohort presented poor outcomes.Based on the stepwise-forward Lo-gistic regression analysis,eight predictors were integrated to determine a new post-endoscopic prognostic scoring system(MH-STRALP);a nomogram was de-termined to present the model.Compared with the previous scores(GBS,Rock-all,ABC,AIMS65,and PNED score),MH-STRALP showed the best prognostic prediction ability with area under the ROC curves(AUROCs)of 0.899 and 0.826 in the training and validation cohorts,respectively.According to the calibration cur-ve,decision curve analysis,and internal cross-validation,the nomogram showed good calibration ability and net clinical benefit in both cohorts.After removing the endoscopic indicators,the pre-endoscopic model(pre-MH-STRALP score)was conducted.Similarly,the pre-MHSTRALP score showed better predictive value(AUROCs of 0.868 and 0.767 in the training and validation cohorts,respectively)than the other pre-endoscopic scores.CONCLUSION The MH-STRALP score and pre-MH-STRALP score are simple,convenient,and accurate tools for prognosis prediction of UGIB,and may be applied for early decision on its management strategies.

Systemic immune-inflammation index for predicting prognosis of colorectal cancer

AIM To investigate the clinical significance of preoperative systemic immune-inflammation index(SII) in patients with colorectal cancer(CRC). METHODS A retrospective analysis of 1383 cases with CRC was performed following radical surgery. SII was calculated with the formula SII =(P × N)/L, where P, N, and L refer to peripheral platelet, neutrophil, and lymphocyte counts, respectively. The clinicopathological features and follow-up data were evaluated to compare SII with other systemic inflammation-based prognostic indices such as the neutrophil-lymphocyte ratio(NLR) and platelet-lymphocyte ratio(PLR) in patients with CRC.RESULTS The optimal cut-off point for SII was defined as 340. The overall survival(OS) and disease-free survival(DFS) were better in patients with low NLR, PLR, and SII(P < 0.05). The SII was an independent predictor of OS and DFS in multivariate analysis. The area under the receiver-operating characteristics(ROC) curve for SII(0.707) was larger than those for NLR(0.602) and PLR(0.566). In contrast to NLR and PLR, SII could effectively discriminate between the TNM subgroups. CONCLUSION SII is a more powerful tool for predicting survival outcome in patients with CRC. It might assist the identification of high-risk patients among patients with the same TNM stage.

In situ observation of austenite grain growth behavior in the simulated coarse-grained heat-affected zone of Ti-microalloyed steels

The austenite grain growth behavior in a simulated coarse-grained heat-affected zone during thermal cycling was investigated via in situ observation. Austenite grains nucleated at ferrite grain boundaries and then grew in different directions through movement of grain boundaries into the ferrite phase. Subsequently, the adjacent austenite grains impinged against each other during the α→γtransformation. After the α→γ transformation, austenite grains coarsened via the coalescence of small grains and via boundary migration between grains. The growth process of austenite grains was a continuous process during heating, isothermal holding, and cooling in simulated thermal cycling. Abundant finely dispersed nanoscale TiN particles in a steel specimen containing 0.012wt% Ti effectively retarded the grain boundary migration, which resulted in refined austenite grains. When the Ti concentration in the steel was increased, the number of TiN particles de- creased and their size coarsened. The big particles were not effective in pinning the austenite grain boundary movement and resulted in coarse austenite grains.

Grain refinement in the coarse-grained region of the heat-affected zone in low-carbon high-strength microalloyed steels

The microstructural features and grain refinement in the coarse-grained region of the heat-affected zone in low-carbon high-strength microalloyed steels were investigated using optical microscopy, scanning electron microscopy, and electron backscattering dif- fraction. The coarse-grained region of the heat-affected zone consists of predominantly bainite and a small proportion of acicular ferrite. Bainite packets are separated by high angle boundaries. Acicular ferrite laths or plates in the coarse-grained region of the heat-affected zone formed prior to bainite packets partition austenite grains into many smaller and separate areas, resulting in fine-grained mixed microstruc- tures. Electron backscattefing diffraction analysis indicates that the average crystallographic grain size of the coarse-grained region of the heat-affected zone reaches 6-9 μm, much smaller than that of anstanite grains.

Toughening mechanisms of a high-strength acicular ferrite steel heavy plate

An ultra-low carbon acicular ferrite steel heavy plate was obtained with an advanced thermo-mechanical control process-relaxed precipitation controlled transformation （TMCP-RPC） at Xiangtan Steel, Valin Group. The heavy plate has a tensile strength of approximately 600 MPa with a lower yield ratio. The impact toughness of the heavy plate achieves 280 J at ？40°C. The fine-grained mixed microstructures of the heavy plate mainly consist of acicular ferrite, granular bainite, and polygonal ferrite. The high strength and excellent toughness of the heavy plate are attributed to the formation of acicular ferrite microstructure. The prevention of blocks of martensite/retained austenite （M/A） and the higher cleanness are also responsible for the superior toughness.

High-temperature stability of retained austenite and plastic deformation mechanism of ultra-fine bainitic steel isothermally treated below Ms

The mechanical properties of the sample and the stability of retained austenite were studied by designing two kinds of ultra-fine bainitic steel with different heat treatment methods austempering above and below Ms(martensite start tem-perature),which were subjected to tensile tests at 20 and 450℃,respectively.The results show that compared to room temperature(20℃)tensile properties,the uniform elongation of the sample at high temperature(450℃)significantly decreased.Specifically,the uniform elongation of the sample austempered above Ms decreased from 8.0%to 3.5%,and the sample austempered below Ms decreased from 10.9%to 3.1%.Additionally,the tensile strength of the sample austempered above Ms significantly decreased(from 1281 to 912 MPa),and the sample austempered below Ms slightly decreased(from 1010 to 974 MPa).This was due to the high carbon content(1.60 wt.%),high mechanical stability,low thermal stability for the retained austenite of the sample austempered below Ms.Besides,the retained austenite decomposed at high temper-atures,the carbon content and transformation driving force were significantly reduced,the transformation rate increased,and the phase transformation content reduced.

Electronic-scale assessment of high-temperature oxidation mechanisms in a novel Fe-based alloy

The development of alloys with high antioxidation performance is limited by the ambiguous details of the oxidation mechanism.Here,based on the structures of internal oxides detected by high-resolution transmission electron microscopy,a hybrid method combining first-principles calculation,climb image nudged elastic band method and quasi-harmonic Debye model has been implemented to explain the oxidation mechanism with an emphasis on the origin of delamination and cracking.The results showed that the delamination of oxides corresponds to the acceleration of diffusion of Cr element caused by lamellar structures.The reduction in the cracking occurrence at high temperature mainly results from the smaller bulk modulus of oxides.Furthermore,the stronger chemical bonds promoted by lamellar structures also correspond to the higher crackingresistance.

Microstructure recognition of steels by machine learning based on visual attention mechanism

U-Net has achieved good performance with the small-scale datasets through skip connections to merge the features of the low-level layers and high-level layers and has been widely utilized in biomedical image segmentation as well as recent microstructure image segregation of the materials.Three representative visual attention mechanism modules,named as squeeze-and-excitation networks,convolutional block attention module,and extended calibration algorithm,were intro-duced into the traditional U-Net architecture to further improve the prediction accuracy.It is found that compared with the original U-Net architecture,the evaluation index of the improved U-Net architecture has been significantly improved for the microstructure segmentation of the steels with the ferrite/martensite composite microstructure and pearlite/ferrite composite microstructure and the complex martensite/austenite island/bainite microstructure,which demonstrates the advantages of the utilization of the visual attention mechanism in the microstructure segregation.The reasons for the accuracy improvement were discussed based on the feature maps analysis.

Effects of Zr addition on microstructure and toughness of simulated CGHAZ in high-strength low-alloy steels

The effect of Zr addition(0.005,0.013,and 0.054 wt.%)on the microstructure and toughness of simulated coarse-grained heat-affected zone in high-strength low-alloy steels was revealed using a Gleeble 2000 thermal simulator.It was observed that elongated MnS inclusions were formed in the lowest Zr-containing steel,while only pure equiaxed ZrO2 existed in the 0.054Zr steel(Zr content of 0.054 wt.%).Complex oxide-sulfide inclusions(ZrO2+MnS)with size of(1.40±0.25)μtm were formed in 0.013Zr steel(Zr content of 0.013 wt.%).The complex inclusions refined the prior austenite grain,and the nucleation of acicular ferrite was promoted compared to those of 0.005Zr steel(Zr content of 0.005 wt.%)and 0.054Zr steel.Consequently,the 0.013Zr steel possessed superior low-temperature impact toughness in relation to 0.005Zr and 0.054Zr steels.Thus,moderate Zr addition can be considered as an effective method to refine the structure and improve the mechanical properties of the coarse-grained heat-affected zone.

Initiation and propagation of localized corrosion induced by(Zr,Ti,Al)-O_(x) inclusions in low-alloy steels in marine environment

The effects of inclusions on localized corrosion of Zr–Ti deoxidized low-alloy steels in marine environment were investigated by various analytical techniques including scanning electron microscopy with X-ray microanalysis(SEM/EDS),confocal Raman microscopy(CRM),and in situ scanning vibrating electrode technique(SVET).It was found that complex(Zr,Ti,Al)-O_(x)inclusions were responsible for the initiation of localized corrosion.Localized corrosion pref-erentially occurred at Fe matrix adjacent to these inclusions and formed micro-gaps.In the early stage of corrosion,catalytic-occluded cells and the diffusion of chloride ions played a major role in the propagation of corrosion,further accelerating the dissolution of Fe matrix and(Zr,Ti,Al)-O_(x)inclusions.Combining SVET and CRM results,it revealed that the maximum anodic current density in local area gradually decreased with prolonged exposure time,indicating that corrosion products covered the steel surface and lowered the propagation rate of corrosion.In the later stage of corrosion,the barrier effect of corrosion products played an important role in inhibiting localized corrosion.

Erosion-corrosion resistance of Mo-Ti- and Ni-Cr-Mo-alloyed medium-carbon martensitic steels: a critical analysis of synergistic effect of erosion and corrosion

Grain refinement renders Mo-Ti-alloyed medium-carbon martensitic steel to exhibit high hardness,high strength,and good toughness,but the erosion-corrosion resistance of steel in a corrosive slurry environment is not known.Mo-Ti-alloyed medium-carbon martensitic steel is compared with Ni-Cr-Mo-alloyed medium-carbon martensitic steel,and the erosion-corrosion resistance of those two steels under impingement by NaCl solution with gravels has been investigated.Three components,pure-corrosion rate,pure-erosion rate,and synergistic effect of erosion and corrosion(SEEC)of erosion-corrosion rate,were quantified.The pure-corrosion and pure-erosion rates of Mo-Ti-alloyed steel were higher than those of Ni-Cr-Mo-alloyed one;however,its erosion-corrosion rate was relatively lower because of a weak SEEC.Surface plastic deformation and work hardening due to gravel impingement were the essential reason for SEEC,which could be reduced by grain refinement,and consequently,Mo-Ti-alloyed steel with finer grains had better erosion-corrosion resistance.Grain refinement could be an effective way to improve the erosion-corrosion resistance of martensitic steels.

Growth Kinetics of Proeutectoid Ferrite in an Fe-0.09C-1.5Mn-0.2Si Steel

Growth kinetics of proeutectoid ferrite, including grain boundary face nucleated ferrite, grain boundary edge nucleated ferrite allotriomorph and intragranular ferrite idiomorph, were experimentally measured in an Fe- 0.09C-1.5Mn-0.2Si steel and compared with theoretical calculation in local equilibrium and paraequilibrium modes. Grain boundary edge nucleated ferrite exhibited larger growth rate than grain boundary face nucleated ferrite and in- tragranular ferrite idiomorph. Experimental kinetics of proeutectoid ferrite was within the window defined by the lo- cal equilibrium and paraequilibrium limits. A transition of growth kinetics from paraequilibrium to local equilibrium was observed in the temperature range of 650--750 ℃, which can be explained in terms of solute drag.

Effect of Zr-deoxidation on microstructure and mechanical behavior of microalloyed heavy plates with low impurity content

The significance of different deoxidation practises on the ductility and impact toughness of next generation of microalloyed heavy plates was elucidated to explore the best deoxidation practice in obtaining required mechanical properties,which was judged by the combined effects of composition,size and number density of inclusions on the ductility of the experimental high-strength low alloy steel.The impurity contents,i.e.,total O+N+S contents,of 82×10^(-6)(Al-killed)and 118×10^(-6)(Zr-killed)have been induced to characterize both the steels.Ductility was characterized using tensile and Charpy V-notch testing.The number,size and composition of the inclusions were characterized using a field emission scanning electron microscope with an energy dispersive spectrometer.In the Al-killed steel,the inclusion structure consisted of titanium nitrides,stringer calcium aluminates and elongated manganese sulfides,whereas in the Zr-killed steel,the inclusion structure consisted of mainly fine spherical oxide inclusions with sulphide shells.The impurity content did not have a significant effect on the number density of inclusions,as with higher and lower impurity content,the number of inclusions was 83.7 and 78.8 mm^(-2),respectively.However,the size distribution of the inclusions,especially the coarse inclusions with their longest length greater than 8μm,differsmuch from each other.The number density of coarse inclusions differs from 0.8 to 1.1 mm^(-2) with processing,and in Al-killed steel,55.5% of the coarse inclusions were titanium nitrides or manganese sulfides,whereas in Zr-killed steel,only 22.5% of the coarse inclusions were titanium nitrides and manganese sulfides.Coarse titanium nitrides were especially detrimental to the impact toughness.The number density of them should be below 0.33 mm-2 in order to guarantee the best possible toughness in the steel in question.The average crystallographic grain size detected by electron backscattered diffraction of Zr-killed steel(4.28±2.70μm)was smaller than that of Al-killed steel(6.00±4.80μm).As a result from the grain refinement and sulphide shape control,Zr-killed steel exhibited superior impact toughness(223±70 J)at -80℃ as compared with Al-killed steel(153±68 J).Thus,Zr-killed steel was observed to provide good performance in terms of mechanical properties as compared with Al-killed steel.