不同方法对根管内氢氧化钙去除效果的micro-CT评价

目的:应用显微CT(micro-computed tomography,micro-CT)建立磨牙根管模型,评价不同方法对氢氧化钙的清除效率。方法:收集2023年10月—2024年2月口腔综合科门诊拔除的11颗磨牙(24个根管),按照标准根管治疗流程,镍钛器械预备完成后,在根管内置入氢氧化钙,1周后,根据不同冲洗方法将样本随机分为侧方开口注射器组、超声荡洗组(EMS组)和声波震荡组(EDDY组)等3组(n=8)。冲洗前后使用micro-CT重建根管系统并使用不同颜色标记独立根管,计算各个根管氢氧化钙体积,比较各组氢氧化钙清除率。采用SPSS 19.0软件包对数据进行统计学分析。结果:3种方法均无法完全去净根管内氢氧化钙。使用次氯酸钠作为冲洗液时,超声荡洗和声波震荡清除效果优于侧方开口冲洗器(P<0.05);超声荡洗和声波震荡去除氢氧化钙效率相当,差异无统计学意义(P>0.05);氢氧化钙残留部位集中于根尖区。结论:Micro-CT能较为高效地重建磨牙根管模型,可用于评价氢氧化钙去除效果。超声荡洗组和声波震荡组清除氢氧化钙效率相当,优于侧方开口注射器组。

Micro LED车灯投影光学系统设计与优化

本文提出了一种基于Micro LED阵列的车灯投影方案,设计了以像素尺寸为80μm×80μm的200×150白光Micro LED阵列作为显示光源,视场角为16°×34°的车灯投影光学系统,并对物面倾斜角度和光学系统结构进行了优化。此外,分别采用反向畸变处理方法和像素灰度调制方法用以解决车灯投影图像的梯形畸变和照度均匀性问题,并搭建了投影实验平台,对图像校正方法进行了验证。实验结果表明:校正后图像梯形畸变系数p1,p2分别从0.0932和0.3680下降至0.0835和0.0373,像面照度均匀性从83.2%提高到93.2%。本文通过对基于Micro LED的倾斜投影车灯光学系统进行优化设计及采用图像校正方法,实现了高光效、低畸变的车灯投影。

光子晶体Micro LED微显示阵列加工及光学特性分析

Micro LED器件具有高亮度、低功耗和高可靠性等优点,但Micro LED显示像素巨量转移和光提取效率低的问题为其应用带来挑战。开发了具有高转移效率和出光效率的单片64×64 Micro LED微显示阵列,提出了倒装型GaN基单片Micro LED微显示阵列芯片和Si基驱动电路的设计方法及集成工艺。通过时域有限差分(FDTD)方法对Micro LED微显示阵列光学特性进行了建模分析,设计了一种提高Micro LED微显示阵列出光效率的光提取结构。结合仿真结果,开发了一种在Micro LED蓝宝石衬底表面制备光子晶体结构的聚焦离子束(FIB)微纳加工工艺,并进行了器件加工。测试结果表明,蓝宝石衬底上加工的光子晶体结构可以提高Micro LED器件的表面出光效率,光功率平均值提升了16.36%,对Micro LED微显示阵列加工及微显示像素光提取问题具有借鉴意义。

Development of carbon composite iron ore micropellets by using the microfines of iron ore and carbon-bearing materials in iron making

Iron ore microfines and concentrate have very limited uses in sintering processes. They are used in pelletization; however, this process is cost intensive. Furthermore, the microfines of non-coking coal and other carbon-bearing materials, e.g., blast-furnace flue dust （BFD） and coke frees, are not used extensively in the metallurgical industry because of operational difficu]ties and handling problems. In the present work, to utilize these microfines, coal composite iron oxide micropellets （2-6 mm in size） were produced through an innovative technique in which lime and molasses were used as binding materials in the micropellets. The micropellets were subsequently treated with CO2 or the industrial waste gas to induce the chemical bond formation. The results show that, at a very high carbon level of 22wt% （38wt% coal）, the cold crushing strength and abrasion index of the micropellets are 2.5-3 kg/cm2 and 5wt%-9wt%, respectively; these values indicate that the pellets are suitable for cold handling. The developed micropellets have strong potential as a heat source in smelting reduction in iron making and sintering to reduce coke breeze. The micropellets produced with BFD and coke fines （8wt%-12wt%） were used in iron ore sin- tering and were observed to reduce the coke breeze consumption by 3%-4%. The quality of the produced sinter was at par with that of the conventional blast-furnace sinter.

Gas Flow Distribution in Pelletizing Shaft Furnace

Through thermal test, cold state experiment, analysis and simulation of thermal process, the gas flow distribution in pelletizing shaft furnace （PSF） was discussed. The results show that there are five flowing trends among them, the downward roasting gas and the upward cooling gas are the most unsteady, which influence flow distribution greatly. Among the operating parameters, the ratio of inflow is a key factor affecting the flow distribution. The roasting and cooling gases will entirely flow into the roasting zone and internal vertical air channels （IVAC）, respectively, if the ratio of inflow is critical. From such a critical operating condition increasing roasting gas flow or decreasing cooling gas flow, the roasting gas starts flowing downwards so as to enter the inside of IVAC the greater the ratio of inflow, the larger the downward flowrate. Among constructional parameters, the width of roasting zone b1, width of IVAC b2 and width of cooling zone b3, and the height of roasting zone h1, height of soaking zone h2 and height of cooling zone hs are the main factors affecting flow distribution. In case the ratio of b2/b3, or h3/h2, or h1/h2 is increased, the upward cooling gas tends to decrease while the downward roasting gas tends to increase with a gradual decrease in the ratio of inflow.

Direct reduction of carburized pre-reduced pellets by microwave heating

A new iron-making process using carburized pre-reduced iron ore pellets and microwave heating is investigated. The pre-reduced pellets, with a porous structure, and fine particles are carburized homogeneously at 400-650 ℃ in a CO atmosphere. The carburized carbon not only acts reaction as a reduction agent, but also absorbs microwave in the reduction process. Hence, the carburized pre-reduced pellets can be rapidly reduced by microwave heating. There are three procedures involved in the process, namely, gas-based pre-reduction, low-temperatttre carburization and deep reduction by microwave heating. Carburized pre-reduced iron ore pellets show a rapid temperature rise that is twice as fast as the results for pre-reduced pellets in the laboratory. This not only improves the efficiency of the microwave heating, but also accelerates the reduction of iron oxides. The temperature of the pre-reduced pellets rises to 1050 ℃ in 45 min when the carburization rate is 2.02%, and the metallization rate and compressive strength reach 94.24% and 1725 N/pellet, respectively.

Evaluation of pharmacokinetics and pharmacodynamics relationships for Salvianolic Acid B micro-porous osmotic pump pellets in angina pectoris rabbit

The work aims to investigate the in vitro release,pharmacokinetics(PK),pharmacodynamics(PD)and PK-PD relationships of Salvianolic Acid B micro-porous osmotic pump pellets(SalB-MPOPs)in angina pectoris New Zealand White(NZW)rabbits,compared with those of SalB immediate-release pellets(SalB-IRPs).The SalB plasma concentrations and Superoxide dismutase levels(PD index)were recorded continuously at predetermined time interval after administration,and the related parameters were calculated by using Win-Nonlin software.The release profile of MPOPs was more sustained than that of IRPs.PK results indicated that the mean C_(max) was significantly lower,the SalB plasma concentrations were steadier,both area under concentration-time curve from 0 to 24 h(AUC_(0-24 h))and from 0 to infinity(AUC_(0-∞))were presented larger,and both the peak concentration time(T_(max))and mean residence time(MRT)were prolonged for MPOPs,as compared with those of IRPs.PD results suggested that peak drug effect(E_(max))was lower and the equilibration rate constant(k_(e0))between the central compartment and the effect compartment was higher of MPOPs vs.those of IRPs.PKePD relationships demonstrated that the effectconcentration-time(ECT)course of MPOPs was clockwise hysteresis loop,and that of IRPs was counter-clockwise hysteresis loop.Collectively,those results demonstrated that MPOPs were potential formulations in treating angina pectoris induced by atherosclerosis.

Preparation of gastro-resistant pellets containing chitosan microspheres for improvement of oral didanosine bioavailability

The purpose of this work was to introduce a new concept of coated pellets containing chitosan microspheres loaded with didadosine for oral administration,aiming at reducing the frequency of administration and improving the bioavailability by a suitable release profile.Chitosan microspheres were produced under fiuidized bed,followed by extrusion and spheronization to obtain pellets with a mean diameter of about 1 mm.The pellets were then coated with Kollidon VA64 and Kollicoat MAE100P in water dispersion to depict a sustained release profile.Conventional hard gelatine capsules were loaded with these pellets and tested in vitro for their release profile of didadosine.Dissolution testing confirmed that chitosan microsphere pellets provides appropriate sustained release up to 2 h behavior for didanosine.

High-chromium vanadium-titanium magnetite all-pellet integrated burden optimization and softening-melting behavior based on flux pellets

High-chromium vanadium-titanium magnetite(HVTM)is a crucial polymetallic-associated resource to be developed.The allpellet operation is a blast furnace trend that aims to reduce carbon dioxide emissions in the future.By referencing the production data of vanadium-titanium magnetite blast furnaces,this study explored the softening-melting behavior of high-chromium vanadium-titanium magnetite and obtained the optimal integrated burden based on flux pellets.The results show that the burden with a composition of 70wt%flux pellets and 30wt%acid pellets exhibits the best softening-melting properties.In comparison to that of the single burden,the softening-melting characteristic temperature of this burden composition was higher.The melting interval first increased from 307 to 362℃and then decreased to 282℃.The maximum pressure drop(ΔPmax)decreased from 26.76 to 19.01 kPa.The permeability index(S)dropped from 4643.5 to 2446.8 kPa·℃.The softening-melting properties of the integrated burden were apparently improved.The acid pellets played a role in withstanding load during the softening process.The flux pellets in the integrated burden exhibited a higher slag melting point,which increased the melting temperature during the melting process.The slag homogeneity and the TiC produced by over-reduction led to the gas permeability deterioration of the single burden.The segregation of the flux and acid pellets in the HVTM proportion and basicity mainly led to the better softening-melting properties of the integrated burden.

基于Micro CT的铜导线短路熔痕孔洞特征分析

导线短路是造成电气火灾的重要原因之一。现行国家标准中将导线短路熔痕分为起火前发生的一次短路熔痕和起火后造成的二次短路熔痕,然而现行国家标准中的鉴定仅停留在定性判断的阶段。火灾现场铜导线短路熔痕特征的量化分析研究是国内外研究人员主要关注的重点。本文应用Micro CT技术对铜导线短路熔痕进行断层扫描检测并重构铜导线短路熔痕的3D图像数据,在此基础上统计、归纳、总结铜导线短路熔痕内部孔洞形态及分布等孔洞特征。研究表明,Micro CT能够全面采集铜导线短路熔痕的整体形态和内部孔洞特征,一次短路熔痕与二次短路熔痕内部孔洞半径、表面积、紧密度的特征数据存在差别,可为短路熔痕定性和定量分析判据研究提供新的理论依据。

Fundamental Study on the Production of ＂Hyper Wood Pellet＂——Effect of Torrefaction Condition on Grinding and Pelletizing Properties

In order to upgrade the conventional wood pellet, Japanese softwood and hardwood chips were torrefied at around 200-350℃, and pelletized. The characteristics of the torrefied material/pellets such as their calorific value, grinding energy, pelletizing energy and elemental composition, were also evaluated in this study. The calorific value rose with increasing torrefaction temperature and exceeded 25 MJ/kg （an increase of nearly 40% compared to the untreated state） for torrefaction at around 350℃. The grinding energy greatly decreased with increasing torrefaction temperature, and the reduction was larger for Japanese oak hardwood chips. The pelletization energy for the torrefied material tended to be slightly smaller than in the untreated case. People named such torrefied pellet as ＂hyper wood pellet＂.

Diffusion and reaction mechanism of limestone and quartz in fluxed iron ore pellet roasting process

The increase to the proportion of fluxed pellets in the blast furnace burden is a useful way to reduce the carbon emissions in the ironmaking process.In this study,the interaction between calcium carbonate and iron ore powder and the mineralization mechanism of fluxed iron ore pellet in the roasting process were investigated through diffusion couple experiments.Scanning electron microscopy with energy dispersive spectroscopy was used to study the elements’diffusion and phase transformation during the roasting process.The results indicated that limestone decomposed into calcium oxide,and magnetite was oxidized to hematite at the early stage of preheating.With the increase in roasting temperature,the diffusion rate of Fe and Ca was obviously accelerated,while the diffusion rate of Si was relatively slow.The order of magnitude of interdiffusion coefficient of Fe_(2)O_(3)-CaO diffusion couple was 10^(−10) m^(2)·s^(−1) at a roasting temperature of 1200℃for 9 h.Ca_(2)Fe_(2)O_(5) was the initial product in the Fe_(2)O_(3)-CaO-SiO_(2) diffusion interface,and then Ca_(2)Fe_(2)O_(5) continued to react with Fe_(2)O_(3) to form CaFe_(2)O_(4).With the expansion of the diffusion region,the sillico-ferrite of calcium liquid phase was produced due to the melting of SiO_(2) into CaFe_(2)O_(4),which can strengthen the consolidation of fluxed pellets.Furthermore,andradite would be formed around a small part of quartz particles,which is also conducive to the consolidation of fluxed pellets.In addition,the principle diagram of limestone and quartz diffusion reaction in the process of fluxed pellet roasting was discussed.

Micro segment analysis of supercritical methane thermal-hydraulic performance and pseudo-boiling in a PCHE straight channel

The printed circuit heat exchanger(PCHE) is receiving wide attention as a new kind of compact heat exchanger and is considered as a promising vaporizer in the LNG process. In this paper, a PCHE straight channel in the length of 500 mm is established, with a semicircular cross section in a diameter of 1.2 mm.Numerical simulation is employed to investigate the flow and heat transfer performance of supercritical methane in the channel. The pseudo-boiling theory is adopted and the liquid-like, two-phase-like, and vapor-like regimes are divided for supercritical methane to analyze the heat transfer and flow features.The results are presented in micro segment to show the local convective heat transfer coefficient and pressure drop. It shows that the convective heat transfer coefficient in segments along the channel has a significant peak feature near the pseudo-critical point and a heat transfer deterioration when the average fluid temperature in the segment is higher than the pseudo-critical point. The reason is explained with the generation of vapor-like film near the channel wall that the peak feature related to a nucleateboiling-like state and heat transfer deterioration related to a film-boiling-like state. The effects of parameters, including mass flow rate, pressure, and wall heat flux on flow and heat transfer were analyzed.In calculating of the averaged heat transfer coefficient of the whole channel, the traditional method shows significant deviation and the micro segment weighted average method is adopted. The pressure drop can mainly be affected by the mass flux and pressure and little affected by the wall heat flux. The peak of the convective heat transfer coefficient can only form at high mass flux, low wall heat flux, and near critical pressure, in which condition the nucleate-boiling-like state is easier to appear. Moreover,heat transfer deterioration will always appear, since the supercritical flow will finally develop into a filmboiling-like state. So heat transfer deterioration should be taken seriously in the design and safe operation of vaporizer PCHE. The study of this work clarified the local heat transfer and flow feature of supercritical methane in microchannel and contributed to the deep understanding of supercritical methane flow of the vaporization process in PCHE.

Preparation of highly stable diclofenac potassium pellet with microcrystalline cellulose by extrusionespheronization

The main purpose of this study is to prepare highly stable diclofenac potassium(DP)pellet with microcrystalline cellulose(MCC)by extrusionespheronization.Using MCC,DP pellets were prepared and the stability was investigated.Related compounds of DP pellets were analyzed by High Pressure Liquid Chromatography(HPLC).After stability test of 60℃/75%RH for 10 d,the values of two main related compounds were 0.94%and 2.17%,respectively.Compatibility tests show that instability of DP was mainly caused by MCC.To improve the stability of DP in presence of MCC,different kinds of stabilizers were investigated.Upon addition of 1.5%(w/w)sodium hydroxide,the primary related compound of pellets was reduced to be 0.159%after stability test of 60℃/75%RH for 50 d.This study demonstrated that MCC induced decomposition of DP upon exposure to moisture could be prohibited by addition of sodium hydroxide.The mechanisms were discussed and residual hydroxyl free radicals in excipients were responsible for decomposition of DP.Finally,this formulation of DP is highly stable with sustained-release behavior.

Micro-CT分析跟骨内骨小梁分布及结构特征

背景:跟骨位于足的后下部,受力较大。跟骨外形复杂且不规则,外周有较薄的皮质骨包绕,内部充满大量的骨小梁,探讨骨小梁的微观结构、走行及分布特征有助于提高对跟骨骨折的认识。目的:采用微计算机断层扫描仪(Micro-CT)扫描跟骨标本获得其影像资料,对其内部骨小梁结构进行分析,探讨跟骨内骨小梁的形态、分布及结构特征。方法:采用Micro-CT连续扫描干燥成人跟骨标本,扫描后获得影像图像,将其以DICOM格式存储。导入影像资料到Hiscan Analyzer软件,显示清晰完整的成人跟骨矢状面、冠状面、水平面的图像,逐层观察骨小梁的走行,依据骨小梁走行特点将跟骨矢状面分为6个部分,在以7 mm为标准的相同厚度下,每个部分选择1个49 mm2等面积的兴趣区,三维重建后获得跟骨及骨小梁的立体微观结构,二值化后运用软件计算感兴趣区域内骨小梁的体积分数、表面密度、骨小梁厚度、骨小梁间隙和骨小梁数量参数。结果与结论:①跟骨表面皮质层很薄,内部充满大量骨松质,在Gissane角的骨皮质明显增厚;②跟骨上部的骨小梁体积分数大于跟骨下部前端、中和三角区、跟骨下后部、跟骨结节部、跟骨底部,跟骨结节部的骨小梁体积分数大于跟骨下部前端、中和三角区、跟骨下后部、跟骨底部;跟骨结节部的骨小梁表面密度大于跟骨下部前端、中和三角区、跟骨底部,跟骨上部、跟骨下后部的骨小梁表面密度大于中和三角区;跟骨上部的骨小梁厚度大于跟骨结节部;中和三角区的骨小梁间隙大于跟骨上部、跟骨结节部;跟骨结节部的骨小梁数量大于中和三角区;③中和三角区主要分布杆状骨小梁,骨小梁表面密度最小、体积分数较小、骨小梁间隙最大;该部位骨质较疏松,受到高冲击力时抗压缩能力差,骨小梁最先发生断裂,是易发生骨折的部位。

Advances in microfluidic-based DNA methylation analysis

DNA methylation has been extensively investigated in recent years,not least because of its known relationship with various diseases.Progress in analytical methods can greatly increase the relevance of DNA methylation studies to both clinical medicine and scientific research.Microflu-idic chips are excellent carriers for molecular analysis,and their use can provide improvements from multiple aspects.On-chip molecular analysis has received extensive attention owing to its advantages of portability,high throughput,low cost,and high efficiency.In recent years,the use of novel microfluidic chips for DNA methylation analysis has been widely reported and has shown obvious superiority to conventional methods.In this review,wefirst focus on DNA methylation and its applications.Then,we discuss advanced microfluidic-based methods for DNA methylation analysis and describe the great progress that has been made in recent years.Finally,we summarize the advantages that microfluidic technology brings to DNA methylation analysis and describe several challenges and perspectives for on-chip DNA methylation analysis.This review should help researchers improve their understanding and make progress in developing microfluidic-based methods for DNA methylation analysis.

高亮绿光氮化镓基Micro-LED微型显示器制备

Micro-LED作为一种新型的显示技术,具有对比度高、响应快及寿命长等优点,已成为当前研究的热点。然而,尽管潜力巨大,Micro-LED技术的商业化之路仍面临诸多技术上的挑战与瓶颈。本文旨在探讨高亮绿光氮化镓基Micro-LED微型显示器的制备过程及其相关技术。基于WVGA041全数字信号电路CMOS硅基驱动电路,制作了0.41 inch、分辨率为800×480的主动式单色绿光Micro-LED微型显示器。利用高精度倒装焊接技术实现了CMOS驱动电路与LED发光芯片的电气连接。结果表明,制备出LED显示芯片正常启亮电压为2.8V,EL光谱峰值波长524nm;在硅基CMOS电路驱动范围内,Micro-LED微型显示器在5V电压下,器件亮度为108000cd/m^(2)(最大亮度可达250000 cd/m^(2)),电流密度达到0.61A/cm^(2)时色坐标为(0.175,0.756)。当电流密度从0.3A/cm^(2)增加到1.3A/cm^(2)时,色坐标从(0.178,0.757)变化到(0.175,0.746),器件的色稳定性能够满足实际应用要求。

Simulation of deuterium pellet ablation and deposition in the EAST tokamak with HPI2 code

Pellet injection is a primary method for fueling the plasma in magnetic confinement devices.For that goal the knowledges of pellet ablation and deposition profiles are critical.In the present study,the pellet fueling code HPI2 was used to predict the ablation and deposition profiles of deuterium pellets injected into a typical H-mode discharge on the EAST tokamak.Pellet ablation and deposition profiles were evaluated for various pellet injection locations,with the aim at optimizing the pellet injection to obtain a deep fueling depth.In this study,we investigate the effect of the injection angle on the deposition depth of the pellet at different velocities and sizes.The ablation and deposition of the injected pellet are mainly studied at each injection position for three different injection angles:0°,45°,and 60°.The pellet injection on the high field side(HFS)can achieve a more ideal deposition depth than on the low field side(LFS).Among these angles,horizontal injection on the middle plane is relatively better on either the HFS or the LFS.When the injection location is 0.468 m below the middle plane on the HFS or 0.40 m above the middle plane of the LFS,it can achieve a similar deposition depth to the one of its corresponding side.When the pre-cooling effect is taken into account,the deposition depth is predicted to increase only slightly when the pellet is launched from the HFS.The findings of this study will serve as a reference for the update of pellet injection systems for the EAST tokamak.

Micro RNAs与急性心肌梗死关系的研究进展

急性心肌梗死(acute myocardial infarction,AMI)是冠状动脉疾病最严重的表现,其引起的心肌组织损伤可促进心力衰竭的发展。尽管近些年由于生活方式的改变、治疗方式(如经皮冠状动脉介入治疗)的发展使AMI的预后得到了改善,但是AMI依旧每年危害着全球700多万人的身心健康,AMI仍然是世界范围内高发病率和高死亡率的主要疾病之一[1]。微小RNA(micro RNAs,miRNAs)是在20世纪90年代被发现的,mi RNAs的研究已经迅速发展成为一个成熟而广阔的领域。mi RNAs存在于几乎所有类型的细胞和细胞的病理生理活动中,包括与心血管系统相关的细胞。本文将mi RNAs对AMI病理生理进程的影响进行综述,希望为临床治疗提供新思路。

Effect of titanium on the sticking of pellets based on hydrogen metallurgy shaft furnace:Behavior analysis and mechanism evolution

Direct reduction based on hydrogen metallurgical gas-based shaft furnace is a promising technology for the efficient and low-carbon smelting of vanadium-titanium magnetite.However,in this process,the sticking of pellets occurs due to the aggregation of metal-lic iron between the contact surfaces of adjacent pellets and has a serious negative effect on the continuous operation.This paper presents a detailed experimental study of the effect of TiO2 on the sticking behavior of pellets during direct reduction under different conditions.Results showed that the sticking index(SI)decreased linearly with the increasing TiO2 addition.This phenomenon can be attributed to the increase in unreduced FeTiO3 during reduction,leading to a decrease in the number and strength of metallic iron interconnections at the sticking interface.When the TiO2 addition amount was raised from 0 to 15wt%at 1100°C,the SI also increased from 0.71%to 59.91%.The connection of the slag phase could be attributed to the sticking at a low reduction temperature,corresponding to the low sticking strength.Moreover,the interconnection of metallic iron became the dominant factor,and the SI increased sharply with the increase in re-duction temperature.TiO2 had a greater effect on SI at a high reduction temperature than at a low reduction temperature.