Modelling,Analysis, and Optimization of the Effects of Pulsed Electrophoretic Deposition Parameters on TiO2 Films Properties Using Desirability Optimization Methodology

Titanium dioxide thin films immobilized over treated stainless steel were prepared using the pulsed electrophoretic deposition technique. The effects of process parameters (deposition time, applied voltage, initial concentration, and duty cycle) on photocatalytic efficiency and adhesion properties were investigated. To optimize the multiple properties of the thin film, a response surface methodology was combined with a desirability optimization methodology. Additionally, a quadratic model was established based on response surface analysis. The precision of the models was defined based on the analysis of variance (ANOVA), R², and the normal plot of residuals. Then, a desirability function was used to optimize the multiple responses of the TiO₂ thin film. The optimum values of applied voltage, catalyst concentration, duty cycle, and deposition time were 4 V, 16.34 g/L, 90% DC, and 150 s, respectively. Under these conditions, the decolorization efficiency of tested dye solution reached 82.75%. The values of critical charges L_C1, L_C2, and L_C3 were 5.9 N, 12.5 N, and 16.7 N, respectively.     

On the Ablation Behavior of Carbon Fiber-Reinforced Plastics during Laser Surface Treatment Using Pulsed Lasers

This contribution discusses the ablation phenomena observed during laser treatment of carbon fiber-reinforced plastics (CFRPs) with pulsed lasers observed employing laser sources with wavelengths of 355 nm, 1064 nm and 10.6 µm and pulse durations from picoseconds (11 ps) to microseconds (14 µs) are analyzed and discussed. In particular, the threshold fluence of the matrix material epoxy (EP) and the damage threshold of CFRP were calculated. Moreover, two general surface pretreatment strategies are investigated, including selective matrix removal and structure generation through indentation (ablation of both, matrix material and fibers) with a cross-like morphology. The surfaces obtained after the laser treatment are characterized by means of optical and scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy is employed for the analysis of composite and constituent materials epoxy and carbon fibers. As a result, different ablation mechanisms, including evaporation and delamination are observed, depending on the employed laser wavelength and pulse duration. For both 355 nm and 1064 nm wavelength, the laser radiation produces only partial ablation of the carbon fibers due to their higher absorption coefficient compared to the epoxy matrix. Although a selective matrix removal without residues is achieved using the pulsed CO₂ laser. Differently, both constituent materials are ablated with the nanosecond pulsed UV laser, producing indentations. The sum of the investigations has shown that existing theories of laser technology, such as the ablation threshold according to Liu et al., can be applied to composite materials only to a limited extent. Furthermore, it has been found that the pronounced heterogeneity of CFRP mostly leads to an inhomogeneous ablation result, both when creating grooves and during selective matrix removal, where the carbon fibers influence the ablation result by their thermal conductivity, depending on fiber direction. Finally, despite the material inhomogeneity, a scanning strategy has been developed to compensate the heterogeneous ablation results regarding structure depth, width and heat affected zone.     

Research on Microstructure and Mechanical Properties of Rheological Die Forging Parts of Al-6.54Zn-2.40Cu-2.35Mg-0.10Zr(-Sc) Alloy

High-strength aluminum alloy (mainly refers to the 7xxx series) is the optimum material for lightweight military equipment. However, this type of aluminum alloy is a wrought aluminum alloy. If it is directly formed by traditional casting methods, there will inevitably be problems such as coarseness, unevenness, looseness, and hot cracking in the structure, which will greatly affect the final performance of the part. Based on the internal cooling with annular electromagnetic stirring (IC-AEMS) method, a new technology of rheological die forging is developed in this paper, and the scale-reduced parts of a brake hub of Al-6.54Zn-2.40Cu-2.35Mg-0.10Zr aluminum alloy were prepared. The influence of IC-AEMS and the addition of rare element Sc on the structure and mechanical properties of the parts was studied. An optical microscope and scanning electron microscope (SEM) were used to observe the microstructure evolution, energy dispersive spectroscopy (EDS) was used to analyze the phase distribution and composition, and the mechanical properties of the parts were tested by uniaxial tensile tests. The results show that the addition of Sc element can effectively refine the grains and improve the strength and elongation of the material; the application of IC-AEMS improves the cooling rate of the melt, increases the effective nucleation rate, and the grains are further refined. Through process optimization, scale-reduced parts of a brake hub with good formability and mechanical properties can be obtained, the ultimate tensile strength is 597.2 ± 3.1 MPa, the yield strength is 517.8 ± 4.3 MPa, and the elongation is 13.7 ± 1.3%.     

3D Numerical Study of External Axial Magnetic Field-Controlled High-Current GMAW Metal Transfer Behavior

For gas metal arc welding (GMAW), increasing the welding current is the most effective way to improve welding efficiency. However, much higher current decreases the welding quality as a result of metal rotating-spray transfer phenomena in the high-current GMAW process. In this work, the external axial magnetic field (EAMF) was applied to the high-current GMAW process to control the metal transfer and decrease the welding spatters. A unified arc-droplet coupled model for high-current GMAW using EAMFs was built to investigate the metal rotating-spray transfer behavior. The temperature fields, flow fields in the arc, and droplet were revealed. Considering all the heat transferred to the molten metal, the Joule heat was found to be the dominant factor affecting the droplet temperature rise, followed by the anode heat. The conductive heat from the arc contributed less than half the value of the other two. Considering the EAMFs of different alternating frequencies, the arc constricting effects and controlled metal transfer behaviors are discussed. The calculated results agree well with the experimental high-speed camera observations.     

ox-LDL对血小板基质金属蛋白酶诱导剂释放的影响

目的 探讨氧化型低密度脂蛋白（ox-LDL）对血小板基质金属蛋白酶诱导剂（EMMPRIN,又名CD147）释放的影响。方法 分别以终浓度25 mg/L、50 mg/L和100 mg/L ox-LDL,对照组（磷酸盐,PBS）和100 mg/L天然LDL体外刺激洗涤血小板,以流式细胞仪检测血小板上CD147、α颗粒膜糖蛋白（CD62P）的表达,酶联免疫吸附法检测血小板上清液中可溶性CD147（sCD147）含量,共聚焦显微镜、透射电子显微镜观察血小板形态改变及颗粒释放。同时,阻断LOX-1受体后,再以流式细胞仪检测ox-LDL（50 mg/L和100 mg/L）刺激的血小板CD147表达。结果 25 mg/L、50 mg/L和100 mg/L ox-LDL处理组血小板CD147相对平均荧光强度（rMFI）（1.01±0.06、1.18±0.07、1.24±0.08）均高于对照组（0.86±0.10, P<0.01）和天然LDL组（0.89±0.11, P<0.01）。LOX-1阻断后,ox-LDL（50 mg/L和100 mg/L）处理组血小板CD147 rMFI（0.96±0.08、1.05±0.07）均下降（P<0.001）。ox-LDL处理后,血小板形态明显改变,并伴随颗粒释放。结论 ox-LDL通过与LOX-1结合诱导了血小板CD147的释放。     

两种黏膜切开刀在食管病变内镜黏膜下剥离术中的有效性及安全性比较

目的比较单极内镜黏膜下剥离术(endoscopic submucosal dissection,ESD)电刀（简称T刀）与Dual刀在ESD治疗食管病变中的有效性及安全性。方法纳入2018年6月—2019年1月期间就诊于苏州大学附属第一医院、诊断为食管病变且行ESD治疗的59例患者,采用随机数字表法分为Dual刀组（30例）及T刀组（29例）。比较两组操作时间、切除速度、完全切除率以及并发症发生率等情况。结果T刀组与Dual刀组患者在性别、年龄、合并症等方面差异均无统计学意义（P>0.05）。T刀组、Dual刀组的手术时间分别为（57.86±24.62）min和（66.28±29.48）min,差异有统计学意义（t=1.189,P=0.024）;切除速度分别为（22.80±7.31）mm2/min和（16.20±7.24）mm2/min,差异有统计学意义（t=3.484,P=0.001）;病灶完全切除率分别为86.2%（25/29）和86.7%（26/30）,差异无统计学意义（χ2=0.108,P=0.742）。T刀组出现并发症2例（6.9%）,Dual刀组并发症共5例（16.7%）,两组并发症发生率比较差异无统计学意义（χ2=0.574,P=0.449）。两组均未见术后穿孔、出血情况。结论在食管病变ESD中,T刀相较于Dual刀能缩短手术时间,提高切除速度,安全性、有效性具有一定优势。     

ox-LDL对血管内皮细胞促聚集和促黏附相关分子表达的影响

目的　观察血管内皮细胞在不同浓度的氧化型低密度脂蛋白（ox-LDL）诱导及诱导不同时间后内皮细胞促聚集和促黏附活性的动态改变及可能机制。方法　将人脐静脉内皮细胞（HUVEC）株接种在6孔培养板,分别加入不同浓度的ox-LDL（50、100和200　mg/L）并孵育不同时间（12、24和48　h）。放射免疫法测定细胞上清液中前列环素（PGI2）和血栓素A2　（TXA2）含量;Western　blot检测HUVEC中组织因子（TF）、细胞间黏附分子1（ICAM-1）和血管细胞黏附分子1（VCAM-1）的表达。结果　量效关系显示,ox-LDL预处理HUVEC　24　h后,ox-LDL呈浓度依赖性促进HUVEC聚集,表现为PGI2/TXA2比值显著下降（P<0.05或P<0.01）;时效关系显示类似的结果,但以24　h作用最为显著;同时,TF的表达随浓度的升高呈升高趋势。此外,ox-LDL还促进HUVEC黏附,表现为ICAM-1和VCAM-1呈浓度依赖性升高。结论　ox-LDL可增强HUVEC促聚集和促黏附活性,其机制可能与其分泌的PGI2/TXA2下降及上调TF、ICAM-　1和VCAM-　1的表达有关。     

不同低密度脂蛋白氧化模型中维生素E的抗氧化效率差异

目的　探讨维生素E（VE）在不同低密度脂蛋白（LDL）氧化模型中抗氧化效率的差异,并揭示VE在体外抗氧化效率不高的可能原因。方法　分别建立LDL主动氧化模型和被动氧化模型,观察LDL与VE共刺激0、12　h以及脂多糖（LPS）与VE共刺激0、3　h后细胞内人α防御素（HNP-1）蛋白及其mRNA水平的表达变化,再通过检测羟基化蛋白（PCO）、丙二醛（MDA）来判断VE是否干扰模型的建立。再将两种氧化模型分别设立氧化模型建立前、后加入VE以及VE（－）组,最后检测不同时间点加入VE后MDA、PCO的变化以分析VE在不同模型中的抗氧化效率差异,并观察细胞内氧自由基水平的波动以判断差异产生的可能原因。　结果　（1）氧化模型中HNP-1mRNA及其蛋白水平的表达均升高,MDA和PCO的生成量也显著升高（P<0.05）。（2）主动氧化模型中不同时间点加入VE后PCO生成量无明显差异（P>0.05）;被动氧化前加VE组氧化产物生成量明显低于被动氧化后加VE组（P<0.05）。不同氧化模型的MDA、PCO生成量在氧化前加VE组和氧化后加VE组降低,且被动氧化模型中下降幅度更加明显,而VE（－）组含量变化趋势相同。（3）不同氧化模型中加入VE,均能够显著提高超氧化物歧化酶（SOD）活性;能够降低自由基水平,且在被动氧化前加VE组自由基水平降低更明显（P>0.05）。　结论　VE的抗氧化效率在被动氧化模型中优于主动氧化模型,与VE的加入时间、胞内自由基水平相关。     

Possible role of intestinal stem cells in the pathophysiology of irritable bowel syndrome

The pathophysiology of irritable bowel syndrome(IBS) is not completely understood. However, several factors are known to play a role in pathophysiology of IBS such as genetics, diet, gut microbiota, gut endocrine cells,stress and low-grade inflammation. Understanding the pathophysiology of IBS may open the way for new treatment approaches. Low density of intestinal stem cells and low differentiation toward enteroendocrine cells has been reported recently in patients with IBS. These abnormalities are believed to be the cause of the low density of enteroendocrine cells seen in patients with IBS.Enteroendocrine cells regulate gastrointestinal motility, secretion, absorption and visceral sensitivity. Gastrointestinal dysmotility, abnormal absorption/secretion and visceral hypersensitivity are all seen in patients with IBS and haven been attributed to the low density the intestinal enteroendocrine cells in these patients.The present review conducted a literature search in Medline(Pub Med) covering the last ten years until November 2019, where articles in English were included.Articles about the intestinal stem cells and their possible role in the pathophysiology of IBS are discussed in the present review. The present review discusses the assumption that intestinal stem cells play a central role in the pathophysiology of IBS and that the other factors known to contribute to the pathophysiology of IBS such as genetics, diet gut microbiota, stress, and lowgrade inflammation exert their effects through affecting the intestinal stem cells.It reports further the data that support this assumption on genetics, diet, gut microbiota, stress with depletion of glutamine, and inflammation.