Microstructure and texture evolution of fine-grained Mg-Zn-Y-Nd alloy micro-tubes for biodegradable vascular stents processed by hot extrusion and rapid cooling

Magnesium alloys have narrow available slip result from close-packed hexagonal structure that limit their processing properties.In the recent work,the Mg-2Zn-0.46Y-0.5Nd,as materials for degradable stents,was applied to produce as-extruded micro-tube with an outer diameter of 3.0mm and a wall thickness of 0.35mm by hot extrusion with an extrusion ratio of 105:1 at 653K and rapid cooling.The fine microstructure of the dynamic recrystallization of as-extruded micro-tube could be preserved by rapid cooling such as water-cooled,resulting in more excellent mechanical properties relative to air-cooled micro-tube.The addition of rare earth elements Y and Nd results in continuous dynamic recrystallization dominated the dynamic recrystallization mechanism.During the hot extrusion process,the activation of the non-basal slip system,especially the pyramidal(c+a)slip,could significantly weaken the texture strength,and the as-extruded micro-tube exhibits weak"RE"texture components(011^(-)1)||ED and(1^(-)21^(-)1)||ED.Hence,the magnesium alloy micro-tube prepared by the rapid cooling has fine microstructure and weak texture,which is favorable for further process and governance.

Micro-Tuber Production in Diploid and Tetraploid Potato after Gamma Irradiation of in Vitro Cuttings for Mutation Induction

Micro-tubers are important propagules in potato breeding and potato production, and they are also dormant and easily transported and therefore good targets for mutation induction in potato mutation breeding. A prerequisite for mutation breeding is to determine optimal mutation treatments. Therefore, radio-sensitivity tests of a tetraploid and a diploid potato to gamma irradiation were undertaken. Effects of different gamma sources on radio-activity were also studied. In vitro potato cuttings were gamma irradiated using a wide dose range (0, 3, 6, 9, 12, 15 and 20 Gy). The irradiated cuttings were then cultured to induce micro-tubers directly in vitro. Micro-tuber morphotypes were assessed after irradiation of cuttings using three gamma sources with emission activities of 1.8, 7.07 and 139 Gy/min. The diploid species (Solanum verrucosum) was more radio-sensitive than the tetraploid cultivar Desirée (Solanum tuberosum). Gamma dose rates had significant influences on subsequent micro-tuber production at various mutant generations. Effects included reductions in the number, size and weight of micro-tubers produced. Gamma dose was more lethal for the diploid potato genotype and micro-tubers produced were small compared to those produced by the tetraploid genotype after irradiation. Different treatments are recommended for diploid and tetraploid potato irradiation in producing large mutant micro-tuber populations. The mutant micro-tuber populations may then be screened for interesting mutations/trait for both genetics and plant breeding purposes.

心包开窗和经皮心包穿刺引流治疗心包积液的比较

目的比较经皮心包穿刺和剑下心包开窗治疗有症状心包积液的结果。方法回顾性分析10年间分别接受经皮心包穿刺和剑下心包开窗手术治疗的心包积液患者的结果。结果160例患者因症状性心包积液接受治疗,其中106例为剑下心包开窗,54例为经皮心包穿刺。经皮心包穿刺组并发症发生率为2%,与心包开窗组的5%相近(P=0.64)。心包开窗组中10例(11%)心包积液复发,6例(6%)出现心包缩窄;而经皮穿刺组有12例(25%)复发,10例(21%)发生缩窄(P=0.01)。单纯心包积液细胞学对恶性疾病的确诊率为19%,低于心包积液联合心包活检的确诊率(45%),有显著性差异(P=0.02)。结论经皮心包穿刺和心包开窗同样有效而安全。心包开窗治疗后的复发率和心包缩窄发生率较低,而且能够通过心包活检提高恶性疾病的确诊率。

微创置管引流奥沙利铂联合足叶乙甙心包腔内低张渗透压灌注治疗老年人恶性心包积液

目的：探讨微创置管序贯心包腔内奥沙利铂（L-OHP）、足叶乙甙（VP-16）低张渗透压灌注治疗老年人恶性心包积液的疗效及安全性.方法：29例老年恶性心包积液于B超定位下参用双腔中心静脉导管（PICC）心包穿刺置管引流术,排尽积液后,心包腔内序贯注入双蒸水、奥沙利铂100mg、VP-16 100mg, 1～2次/周,连续2～3周.结果：全组平均注药次数为3次.完全缓解18例（62.1%）,部分缓解11例（37.9%）,有效率93.3%,中位无进展生存时间7.3个月,微创置管化疗后多为I度胃肠道反应、I度骨髓抑制、窦性心律失常.结论：微创置管序贯心包腔内注射双蒸水、L-OHP、VP-16是治疗老年人恶性心包积液一种有效安全的方法.

Pericardial decompression syndrome: A comprehensive review

Pericardial decompression syndrome(PDS)is an infrequent,life-threatening complication following pericardial drainage for cardiac tamponade physiology.PDS usually develops after initial clinical improvement following pericardiocentesis and is significantly underreported and may be overlooked in the clinical practice.Although the precise mechanisms resulting in PDS are not well understood,this seems to be highly associated with patients who have some underlying ventricular dysfunction.Physicians performing pericardial drainage should be mindful of the risk factors associated with the procedure including the rare potential for the development of PDS.

Interconnected graphene/polymer micro-tube piping composites for liquid sensing

Detection and analysis of volatile organic compounds （VOCs） as pollutants in the atmosphere and liquids are of great significance because of the detrimental effects of VOCs. A polymer-coated graphene micro-tube piping （GMP） structure with a cross-linked and interconnected channel network was synthesized for liquid sensing. By virtue of their unique cross-linked and interconnected channel network configuration, polycrystalline conformation, and the support of a polymer layer, the resistivity of the 3D hollow micro-tubing GMPs was sensitive to strain, ensuring high sensitivity of the liquid sensor （R/Ro of -4 × 10^3% for pure acetone and R/Ro of -105% for 0.01 wt.% acetone solution）. Due to the capillary force, the interfaces of the 3D structures can speed up the penetration of solvents into the polymer, thus promote distinct selectivity within seconds and significantly decrease the response time. Owing to their good selectivity, high sensitivity, rapid response and flexibility, and the ease of use of the sensors and the simplicity of the fabrication processes, the GMP/polymer composites should be a good candidate for liquid sensing.

Processing of a Novel Zn Alloy Micro-Tube for Biodegradable Vascular Stent Application

In recent years, zinc based alloys as a new biodegradable metal material aroused intensive interests. However, the processing of Zn alloys micro-tubes （named slender-diameter and thin-walled tubes） is very difficult due to their HCP crystal structure and unfavorable mechanical properties. This study aimed to develop a novel technique to produce micro-tube of Zn alloy with good performance for biodegrad- able vascular stent application. In the present work, a processing method that combined drilling, cold rolling and optimized drawing was proposed to produce the novel Zn-5Mg-1Fe （wt%） alloy micro- tubes. The micro-tube with outer diameter of 2.5 mm and thickness of 130 μm was fabricated by this method and its dimension errors are within 10 μm. The micro-tube exhibits a fine and homogeneous microstructure, and the ultimate tensile strength and ductility are more than 220 MPa and 20% respectively. In addition, the micro-tube and stents of Zn alloy exhibit superior in vitro corrosion and expansion performance. It could be concluded that the novel Zn alloy micro-tube fabricated by above method might be a promising candidate material for biodegradable stent.

Rational design, synthesis and prospect of biodegradable magnesium alloy vascular stents

Biodegradable magnesium(Mg) alloys are expected to be promising materials for cardiovascular stents(CVS), which can avoid the longterm clinical problems of current CVS, such as in-stent restenosis, late stent thrombosis, etc. Mg alloy stents exhibit superior biocompatibility and tunable biodegradability, compared with conventional permanent metallic stents. However, the poor formability and non-uniform corrosion of Mg alloy stents hinder their clinical application of CVS. This review focuses on the development of Mg alloys for CVS in recent years.According to the results of bibliometric analysis, we analyzed different biodegradable Mg alloy systems. Moreover, the structural design strategies for Mg alloy stents that can reduce the stress concentration, as well as the surface modification methods to control the corrosion behavior and biological performance of Mg alloy stents are also highlighted. At last, this review systematically discussed the potential directions and challenges of biodegradable magnesium stents(BMgS) in cardiovascular fields.

Torsional wave in a circular micro-tube with clogging attached to the inner surface

In the present paper, we study the torsional wave propagation along a micro-tube with clog- ging attached to its inner surface. The clogging accumulated on the inner surface of the tube is modeled as an ＂elastic membrane＂ which is described by the so-called surface elasticity. A power-series solution is particularly developed for the lowest order of wave propagation. The dispersion diagram of the lowest-order wave is numerically presented with the surface （clogging） effect.

Numerical Simulations of a Micro-Channel Wall-Tube Condenser for Domestic Refrigerators

In recent years, microchannel heat exchangers have begun to be used in refrigeration and air conditioning systems. This paper introduces a microchannel condenser for domestic refrigerators with a theoretical model to evaluate its performance. The model was used to obtain the optimal design parameters for different numbers of tubes and tube lengths. The results show that the needed tube height of the down- ward section decreases with the number of tubes and the tube diameter. Compared with the original con- denser, the present optimal design parameters can reduce the total metal mass by 48.6% for the two wall two side design and by 26% for the two wall one side design. Thus, the present condenser is much better than the condensers usually used in actual domestic refrigerators.

Dielectric relaxation behavior of SDS/β-CD organized self-assembly in dilute aqueous solution

Dielectric relaxation behavior of SDS/β-CD self-organized with mass concentrations from 1% to 7% was investigated. The phase microstructure of SDS/β-CD aqueous solution was confirmed by analyzing the dielectric parameters. The dielectric relaxation behavior was attributed to the interracial polarization between vesicle and medium, and the relaxation distribution parameter can indicate the shape transition from vesicles to microtubules with increasing concentration. Dielectric relaxation provided a new method to study surfactant organized self-assembly.