Forum in Suzhou casts eyes on STEM education

The International STEM Education Forum in Suzhouopened in Soochow University on May 30, attractingscholars and experts in STEM education and cultivatingtechnology talents from home and abroad.Under the guidance of Department of Foreign ExpertsServices, Ministry of Science and Technology(MOST ), the event was jointly organized by ForeignTalent Research Center,Ministry of Science and Technologyand China Guanghua Foundation.

Biliary casts after liver transplantation: Morphology and biochemical analysis

AIM:To investigate the pathogenesis of biliary casts after liver transplantation relative to their morphology and biochemical markers.METHODS:The microstructure of biliary casts was assessed using scanning electron microscopy and Hematoxylin and eosin staining assessed their histology.The expression levels of CD3,CD5,CD34,CD68 and CD79a in these biliary casts were evaluated immunohistochemically.RESULTS:Biliary casts differed widely in their microstructure,with some containing blood vessels positive for CD34 and collagen fibers with positive Masson staining.Large numbers of neutrophils and other inflammatory cells were present,but only on the edge of the biliary casts;although the boundaries were clear without crossover.None of the biliary casts contained T-lymphocytes,B-lymphocytes,macrophages and other inflammatory cells.CONCLUSION:The microcostructure of biliary casts differed.Bacteria and acute rejection are not clearly related to their formation.

Functional Microvascular Anatomy of the Horse Eye: A Scanning Electron Microscopic Study of Corrosion Casts

Objective: This study presents the microvasculature of the horse iris, ciliary process, retina, and choroid and discusses the functional significance of the vasculature. Procedure: Seven horses were used for this study. The ocular vascular system was injected with methylmethacrylate resin via the carotid artery, and the vascular corrosion casts were observed using a scanning electron microscope. Results: The iridial vessels showed a wavy course. The ciliary process was supplied by 2 arterial routes: the iridial and ciliary arterial circles. The subjects displayed a paurangiotic retina with retinal vessels extending only a short distance around the disc. The retinal arterioles and venules ran in closely related pairs, and the capillaries formed hairpin loops. No central retinal artery was seen in the equine eyes examined. The choriocapillaris in the avascular retina was arranged in honeycomb hexagon lobules and formed a more densely packed network than that in the vascular retina. There were 2 distinct venous drainage systems in the horse choroid: the vortex veins and the posterior ciliary veins. The vortex vein ampulla was flattened and showed a slit-like lumen at the merge site with the ophthalmic vein. The vortex veins demonstrated a marked constriction before leaving the eye. Discussion: The 2 choroidal drainage systems may compensate each other in event of occlusion. The ampulla and the constriction in the vortex veins may act as a valve regulating the blood flow to keep the eye at an optimum size and the intraocular pressure within the normal physiological range.

Lower limb intracast pressures generated by different types of immobilisation casts

AIM To determine if complete, split casts and backslabs [plaster of Paris(POP) and fiberglass] generate different intracast pressures and pain. METHODS Increased swelling within casts was modeled by a closed water system attached to an expandable bag placed directly under different types of casts applied to a healthy lower limb. Complete fiberglass and POP casts, split casts and backslabs were applied. Twenty-five milliliter aliquots of saline were injected into the system and the generated intracast pressures were measured using a sphygmomanometer. The subject was blinded to the pressure scores to avoid bias. All casts were applied to the same right limb on the same subject to avoid the effects of variations in anatomy or physiology on intracast pressures. Pain levels were evaluated using the Visual Analogue Score after each sequential saline injection. Each type of cast was reapplied four times and the measurements were repeated on four separate occasions. Sample sizes were determined by a pre-study 90% power calculation to detect a 20% difference in intracast pressures between cast groups. RESULTS A significant difference between the various types of casts was noted when the saline volume was greater than 100 mL(P = 0.009). The greatest intracast pressure was generated by complete fiberglass casts, which were significantly higher than complete POP casts or backslabs(P = 0.018 and P = 0.008 respectively) at intracast saline volumes of 100 mL and higher. Backslabs produced a significantly lower intracast pressure compared to complete POP only once the saline volume within casts exceeded 225 mL(P = 0.009). Intracast pressures were significantly lower in split casts(P = 0.003). Split POP and fiberglass casts produced the lowest intracast pressures, even compared to backslabs(P = 0.009). Complete fiberglass casts generated the highest pain levels at manometer pressures of 75 mm Hg and greater(P = 0.001). Split fiberglass casts had significantly reduced pain levels(P = 0.001). In contrast, a split complete POP cast did not produce significantly reduced pain levels at pressures between 25-150 mmH g. There was no difference in pain generated by complete POP and backslabs at manometer pressures of 200 mm Hg and lower. CONCLUSION Fibreglass casts generate significantly higher intracast pressures and pain than POP casts. Split casts cause lower intracast pressures regardless of material, than complete casts and backslabs.

A Model for Diagnosing the Formation of Internal Cracks in Continuously CastSlabs

The internal cracks in continuously cast slabs are attributed to the excessive tensile strain occurring at the solidifying frontduring the continuous casting process. Based on the understanding, a model for diagnosing the formation of the internal cracks was established, in which the strains at the solidifying front caused by' bulging, straightening or unbending, and roll misalignment were calculated and compared with a critical strain value to estimate whether the internal cracks form. Moreover, the established model was appliedto a real slab caster to reveal the distribution of the strains in casting direction and its effect on the internal cracks. It was proved that themodel was reliable and useful for optimizing the operation of continuous casting.

Three-dimensional analysis of the gap space under forearm casts

Purpose:Secondary displacement represents a frequent complication of conservative treatment of fractures,particularly of the distal radius.The gap space between skin and cast may lead to a certain degree movements and this increased mobility might favor redisplacement.The aim of this study was to develop a new 3D method,to measure the gap space in all 3 geometrical planes,and to validate this new technique in a clinical setting of distal radius fractures.Methods:This study applies 3D imaging to measure the space between plaster and skin as a potential factor of secondary displacement and therefore the failure of conservative treatment.We developed and validated a new methodology to analyze and compare different forearm casts made of plaster of Paris and fiberglass.An unpaired t-test was performed to document differences between the investigated parameters between plaster of Paris and fiberglass casts.The significance level was set at p<0.05.Results:In a series of 15 cases,we found the width of the gap space to average 4 mm,being slightly inferior on the radial side.Comparing the two different casting materials,plaster of Paris and fiberglass,we found a significantly larger variance of space under casts made of the first material(p=0.39).A roughness analysis showed also a markedly significantly higher irregularity of the undersurface of plaster of Paris as compared with fiberglass.Conclusion:This study allows for a better understanding of the nature of the"gap space"between cast and skin and will contribute to develop and improve new immobilization techniques and materials.

Monte Carlo simulation of a cone-beam CT system for lightweight casts

Cone-beam computed tomography(CBCT),a modern technique with many applications,is becoming increasingly important and essential in many areas of economics and life.CBCT equipment has been commercialized in both hardware and software.However,having a device system suitable for a specific group of objects will be the best.This work used Monte Carlo simulation to optimize the design of a Cone-beam Computed Tomography(CBCT)for lightweight and small-size casts.Factors affecting image quality such as radiation-source,flat-panel detector,and geometrical distance were investigated.Simulation results indicate that an X-ray generator with a focal spot size of 4×4µm^(2),high voltage of 240 kV,and a radiation intensity of 10^(13) photon/s with a flat panel CsI(Tl)detector of 0.3 mm thickness and a pixel size of 0.1–0.2 mm,is suitable for a CBCT to inspect small objects in industry.The Monte Carlo model was validated against experiments and to evaluate some characteristics of the existing system.

PRELIMINARY RESEARCH ON NEWLY DISCOVERED STRATA AND WEDGE CASTS DATING 0.73—0.90 Ma B. P. IN ZHOUKOUDIAN REGION, BEIJING

During 1985—1987, the authors discovered new fossiliferous strata bearing ice wedge casts of Early Pleistocene on the northern Taipingshan in Zhoukoudian, and established Taipingshan Formation （Q1t）.

Impacts of wetting-drying cycles on short-term carbon and nitrogen dynamics in Amynthas earthworm casts

Effects of earthworm casts on soil nutrient dynamics and their responses to changing moisture availability in subtropical ecosystems remain poorly understood.This study aimed to examine short-term carbon(C)and nitrogen(N)dynamics and their interactions with wetting-drying cycles in three different structural forms(i.e.,granular,globular,and heap-like)of Amynthas earthworm casts.The rates of C and N mineralization in the earthworm casts were examined under two different wetting-drying cycles(i.e.,2-d and 4-d wetting intervals)using a rainfall simulation experiment.After three simulated rainfall events,subsamples of the earthworm casts were further incubated for 4 d for the determination of CO2 and N2O fluxes.The results of this study indicated that the impacts of wetting-drying cycles on the short-term C and N dynamics were highly variable among the three cast forms,but wetting-drying cycles significantly reduced the cumulative CO2 and N2O fluxes by 62%-83%and 57%-85%,respectively,when compared to the control without being subjected to any rainfall events.The C mineralization rates in different cast forms were affected by the amount of organic substrates and N content in casts,which were associated with the food preference and selection of earthworms.Meanwhile,the cumulative N2O fluxes did not differ among the three cast forms.Repeated wetting and drying of casts not only enhanced aggregate stability by promoting bonds between the cast particles,but also inhibited microbial survival and growth during the prolonged drying period,which together hindered decomposition and denitrification.Our findings demonstrated that the interactions between the structural forms,aggregate dynamics,and C and N cycling in the earthworm casts were highly complex.

甘草多糖对鸡肉品质及其相关候选基因表达的影响

为探究甘草多糖对鸡肉品质的影响,设计不同水平的甘草多糖添加至日粮中,测定爱拔益加肉鸡的肉质性状和相关基因在肉质中的含量,以此来研究日粮中添加不同水平甘草多糖对其肉质的影响情况;并利用转录组测序技术(RNA-SEQ)分析了日粮中添加不同水平甘草多糖饲喂的肉鸡胸肌组织样品的转录组,从而筛选出能够调控肉质性状的关键基因,并利用实时荧光定量PCR技术进行验证。结果表明,在日粮中添加300、600、900 mg/kg甘草多糖的试验组鸡的胸肌的肉质指标肉色、pH1、pH24、蒸煮损失和滴定损失与对照组均无显著差异(P>0.05),但发现随着日粮甘草多糖的增加,鸡的肉质指标有着不同程度的改善。在日粮中添加300、600 mg/kg甘草多糖均增加了鸡胸肌中LPL基因、PPARγ基因、FABP3基因、CAST基因的相对表达量,在日粮中添加300、600 mg/kg甘草多糖降低了鸡胸肌中CAPN2基因的相对表达量;在日粮中添加900 mg/kg甘草多糖降低了LPL基因、PPARγ基因、FABP3基因、CAST基因的相对表达量。

钙蛋白酶抑制蛋白对畜禽肉品质影响的研究进展

钙蛋白酶抑制蛋白(calpastatin,CAST)是由CAST基因编码,是内源性专一抑制钙蛋白酶(calpain,CAPN)活性的抑制蛋白,是CAPN系统家族成员之一,可以调节脊椎动物体内CAPN活性。CAST能控制肌原纤维中蛋白质降解,影响肌细胞的生长速度及肌肉嫩度。CAST活性减弱或活化CAPN都能增加肌肉嫩度,从而改善肉品质。CAST基因可作为猪、牛、羊改善肉品质的候选基因。文章综述了CAST结构、CAST调控机制,分析了其对畜禽肉品质的影响,以期为推进CAST在改善畜禽肉品质中的进一步应用提供参考。

藜麦对芦花鸡肉质相关基因表达的影响

为研究藜麦籽实对芦花鸡肉品质及肉质相关基因表达水平的影响,试验选用49日龄体重为(1476.21±101.39)g且健康状况良好的雌性芦花鸡120只,将其随机分成4个处理组,每个处理3个重复,每个重复包含10只鸡。对照组(CK组)饲喂藜麦籽实添加量为0的基础饲粮,各试验组(Q4、Q8、Q12组)饲喂藜麦籽实添加量为4%、8%、12%的试验饲粮,整个试验期为75 d,包括3 d预试期和72 d正试期。饲喂结束后屠宰并测定肉品质及肉质相关基因的表达量。结果表明:(1)与CK组相比,Q4、Q12组胸肌组织中CAPN1基因mRNA相对表达量显著提高(P <0.05);各试验组CAST基因及Q4组LRP1基因m RNA在胸肌中的相对表达量显著降低(P <0.05)。(2)与CK组相比,Q4、Q8组腿肌组织中CAPN1基因、Q4组CAST基因及Q8、Q12组LRP1基因m RNA的相对表达量显著提高(P <0.05)。(3)在胸肌组织中,LRP1基因表达水平与肌肉剪切力呈显著正相关(P <0.05),CAPN1基因的表达水平与滴水损失呈显著负相关(P <0.05)。(4)在腿肌组织中,LRP1基因的表达水平与蒸煮损失、剪切力呈显著正相关(P <0.05);CAPN1基因表达水平与熟肉率呈显著正相关(P <0.05)。由此可见,饲粮中添加藜麦籽实(原粮)对肌肉组织中CAST、LRP1、CAPN1基因的表达量有一定影响,且LRP1、CAST、CAPN1基因与嫩度相关肉品质指标存在显著相关性。

Strength and elastic modulus enhancement in Mg-Li-Al matrix composites reinforced by ex situ TiB2 particles via stir casting

A novel Mg^(-1)0Li-3Al(wt.%,LA103)matrix composite reinforced by ex situ micron TiB_(2) particles was developed in the present study.The ball milling and cold pressing pretreatment of the reinforcements made it feasible to prepare this material under stir casting conditions with good dispersion.The microstructure and mechanical properties of the composites prepared by different pretreatment methods were analyzed in detail.The TiB_(2) particles in the Al-TiB_(2)/LA103 composite using the pretreatment process were uniformly distributed in the microstructure due to the formation of highly wettable core-shell units in the melt.Compared with the matrix alloys,the Al-TiB_(2)/LA103 composite exhibited effective strength and elastic modulus improvements while maintaining acceptable elongation.The strengthening effect in the composites was mainly attributed to the strong grain refining effect of TiB2.This work shows a balance of high specific modulus(36.1 GPa·cm^(3)·g^(-1))and elongation(8.4%)with the conventional stir casting path,which is of considerable application value.

Volume-averaged modeling of multiphase solidification with equiaxed crystal sedimentation in a steel ingot

Macrosegregation is a critical factor that limits the mechanical properties of materials.The impact of equiaxed crystal sedimentation on macrosegregation has been extensively studied,as it plays a significant role in determining the distribution of alloying elements and impurities within a material.To improve macrosegregation in steel connecting shafts,a multiphase solidification model that couples melt flow,heat transfer,microstructure evolution,and solute transport was established based on the volume-averaged Eulerian-Eulerian approach.In this model,the effects of liquid phase,equiaxed crystals,columnar dendrites,and columnar-to-equiaxed transition(CET)during solidification and evolution of microstructure can be considered simultaneously.The sedimentation of equiaxed crystals contributes to negative macrosegregation,where regions between columnar dendrites and equiaxed crystals undergo significant A-type positive macrosegregation due to the CET.Additionally,noticeable positive macrosegregation occurs in the area of final solidification in the ingot.The improvement in macrosegregation is beneficial for enhancing the mechanical properties of connecting shafts.To mitigate the thermal convection of molten steel resulting from excessive superheating,reducing the superheating during casting without employing external fields or altering the design of the ingot mold is indeed an effective approach to control macrosegregation.

Data-driven casting defect prediction model for sand casting based on random forest classification algorithm

The complex sand-casting process combined with the interactions between process parameters makes it difficult to control the casting quality,resulting in a high scrap rate.A strategy based on a data-driven model was proposed to reduce casting defects and improve production efficiency,which includes the random forest(RF)classification model,the feature importance analysis,and the process parameters optimization with Monte Carlo simulation.The collected data includes four types of defects and corresponding process parameters were used to construct the RF model.Classification results show a recall rate above 90% for all categories.The Gini Index was used to assess the importance of the process parameters in the formation of various defects in the RF model.Finally,the classification model was applied to different production conditions for quality prediction.In the case of process parameters optimization for gas porosity defects,this model serves as an experimental process in the Monte Carlo method to estimate a better temperature distribution.The prediction model,when applied to the factory,greatly improved the efficiency of defect detection.Results show that the scrap rate decreased from 10.16% to 6.68%.

Research advances of magnesium and magnesium alloys globally in 2023

Magnesium materials have attracted the attention of many researchers,and the related research is expanding.This article summarizes the advance in the research and development of magnesium materials globally in 2023 from bibliometric and scientific perspectives.More than 4680 articles on Mg and its alloys were published and indexed in the Web of Science(WoS)Core Collection database last year.The bibliometric analyses show that the traditional structural Mg alloys,functional Mg materials,and corrosion and protection of Mg alloys are still the main research focus.Therefore,this review paper mainly focuses on the research progress of Mg cast alloys,Mg wrought alloys,bio-magnesium alloys,Mg-based energy storage materials,corrosion and protection of Mg alloys in 2023.In addition,future research directions are proposed based on the challenges and obstacles identified throughout this review.

物化预处理-生化组合工艺处理草甘膦生产废水工程实例

对不同工艺废水采用物化方法分质预处理后,利用厌氧-缺氧-CAST组合工艺处理综合废水,设计处理量为470 m^(3)/d。运行实践表明:中和反应-混凝沉淀对总磷的去除率可以达到46%,整个工艺处理出水COD稳定低于500 mg/L,总磷稳定低于8 mg/L,出水水质达到接管要求。

Intelligent casting:Empowering the future foundry industry

Emerging technological advances are reshaping the casting sector in latest decades.Casting technology is evolving towards intelligent casting paradigm that involves automation,greenization and intelligentization,which attracts more and more attention from the academic and industry communities.In this paper,the main features of casting technology were briefly summarized and forecasted,and the recent developments of key technologies and the innovative efforts made in promoting intelligent casting process were discussed.Moreover,the technical visions of intelligent casting process were also put forward.The key technologies for intelligent casting process comprise 3D printing technologies,intelligent mold technologies and intelligent process control technologies.In future,the intelligent mold that derived from mold with sensors,control devices and actuators will probably incorporate the Internet of Things,online inspection,embedded simulation,decision-making and control system,and other technologies to form intelligent cyber-physical casting system,which may pave the way to realize intelligent casting.It is promising that the intelligent casting process will eventually achieve the goal of real-time process optimization and full-scale control,with the defects,microstructure,performance,and service life of the fabricated castings can be accurately predicted and tailored.

Thermal and mechanical behavior of casting copper alloy wheel during wheel and belt continuous casting process

To investigate the thermal and mechanical behavior of casting wheel,a two-dimensional thermoelastic-plastic finite element model was used to predict the temperature,stress and distortion distribution of the casting wheel during the wheel and belt continuous casting process.The effects of grinding thickness and casting speed on the thermal and mechanical behaviors of the center of the hot face of the casting wheel were discussed in detail.In each rotation,the casting wheel passes through four different spray zones.The results show that the temperature distribution of the casting wheel in different spray zones is similar,the temperature of the hot face is the highest and the temperature reaches the peak in the spray zoneⅢ.The stress and distortion depend on the temperature distribution,and the maximum stress and distortion of the hot face are 358.2 MPa and 1.82 mm,respectively.The temperature at the center of the hot face decreases with increasing grinding thickness and increases with increasing casting speed.

Microstructure and properties of LZQT600-3 HCCDIBs for plunger pump cylinder

It is important to improve the comprehensive performance of the ductile iron bars(DIBs)for the cylinder block of the extra high pressure hydraulic plunger pump and accelerate the industrial application.In this work,the LZQT600-3 DIBs with the diameter of 145 mm were prepared by the horizontal continuous casting(HCC)process,that is,LZQT600-3 HCCDIBs.The microstructure and room temperature tensile properties of different sections[left-edge(surface layer),left-1/2R(left half of the radius),and the center of the HCCDIBs]were studied.The results show that the spheroidization of LZQT600-3 HCCDIBs matrix from the left-edge,left-1/2R to the center is at nodulizing grade II and above.As the cooling rate gradually decreases from surface to the center of the HCCIBs,the number of spheroidized graphite is gradually reduced,the size is gradually increased,the shape factor is decreased,and the pearlite content and lamellate spacing are increased.Along the horizontal direction of the section,the hardness of the material is distributed symmetrically around the center of the HCCDIBs.In the vertical direction,the hardness distribution in the center of the HCCDIBs is asymmetrical due to the gravity during the solidification process.Therefore,the microstructure in the lower part of the section solidifies relatively quickly.The left-edge has the best tensile mechanical properties,and the ultimate tensile strength,yield tensile strength and elongation are 597.3 MPa,418.5 MPa and 9.6%,respectively.The tensile fracture belongs to the ductile-brittle hybrid fracture.The comprehensive performances of LZQT600-3 HCCDIBs meet the actual application requirements of ultra-high pressure hydraulic plunger pump cylinder.