Sensitivity analysis of the scattering parameters of microwave filters using the adjoint network method

A novel approach is presented to calculate the sensitivities of the scattering parameters of microwave filters obtained with the full‐wave mode‐matching (MM) technique. Using only the MM simulation of the original network, the sensitivities of the scattering parameters with respect to all designable parameters are obtained. The adjoint network method (ANM) is applied to the generalized scattering matrices of the different filter components. This guarantees good accuracy of the calculated sensitivities. The implementation details are discussed for N‐resonator ridge waveguide filters. Excellent agreement is obtained between the sensitivities calculated using ANM and those obtained using the expensive central differences. © 2006 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2006.     

缺血性糖尿病下肢病变的膝下动脉成形术

目的探讨膝下动脉的球囊成形术在治疗糖尿病缺血性下肢病变中的价值。方法对５３例糖尿病合并缺血性下肢病变患者６４侧缺血性下肢进行膝下动脉Deep球囊扩张成形术。对比患者手术前后临床症状的改变及足部溃疡的变化。结果５３例患者共１１９支动脉分支接受PTA治疗，５０例患者的１０１个分支成功地开通，技术成功率为８４．９％，所有５０例患者的临床症状均明显缓解，足部溃疡均变小，无需截肢。结论膝下动脉的球囊成形术是治疗缺血性糖尿病下肢病变安全有效的微创手段     

Current approach to the management of gastrinoma and insulinoma in adults with multiple endocrine neoplasia type I

Although there is a recent increase in the use of the isolated pancreatic islets of the rat in the transplantation and functional studies, there has been no detailed quantitative assessment on the size and cellular constituents of islets after the isolation procedure. The present work was undertaken to study the size classes of the isolated islets and the morphometry of their cellular populations. Islets of the rat pancreas were isolated by using the intraductal collagenase digestion technique, the most commonly used procedure for the isolation of pancreatic islets. Different endocrine cells of the isolated islets were stained by immunoperoxidase staining techniques. The distribution of the cellular constituents of the isolated islets was similar to that of the intact islets of the normal pancreas; A, D, and PP cells were peripherally arranged around the centrally located B cells. However, morphometric quantitative study showed that the percent volume and percent number of A, D, and PP cells of the isolated islets were lower than those of the corresponding intact ones. Further, the mean true diameter of the isolated islets was lower than that of the intact ones. These data indicate loss of islet cells during the process of isolation. Most of the lost cells were from the periphery of islets. This may provide an explanation for the incomplete metabolic control and recurrence of hyperglycemia encountered after isolated islet transplantation in the treatment of diabetes mellitus. It seems that further refinements of the isolation techniques are necessary to obtain islet tissue with total cellular integrity, before a complete success in transplantation could be achieved.     

Optimal motion planning for parallel robots via convex optimization and receding horizon

In this paper, the problem of motion planning for parallel robots in the presence of static and dynamic obstacles has been investigated. The proposed algorithm can be regarded as a synergy of convex optimization with discrete optimization and receding horizon. This algorithm has several advantages, including absence of trapping in local optimums and a high computational speed. This problem has been fully analyzed for two three-DOF parallel robots, ie 3s-RPR parallel mechanism and the so-called Tripteron, while the shortest path is selected as the objective function. It should be noted that the first case study is a parallel mechanism with complex singularity loci expression from a convex optimization problem standpoint, while the second case is a parallel manipulator for which each limb has two links, an issue which increases the complexity of the optimization problem. Since some of the constraints are non-convex, two approaches are introduced in order to convexify them: (1) A McCormick-based relaxation merged with a branch-and-prune algorithm to prevent it from becoming too loose and (2) a first-order approximation which linearizes the non-convex quadratic constraints. The computational time for the approaches presented in this paper is considerably low, which will pave the way for online applications.     

Ce3+-doped LaF3 nanoparticles: Wet-chemical synthesis and photo-physical characteristics “optical properties of LaF3:Ce nanomaterials”

The most effective process parameters were determined to synthesize spherical LaF₃ nanoparticles with controllable size based on ethylenediaminetetraacetic acid (EDTA) via co-precipitation technique. Thermogravimetricdifferential thermal analysis, X-ray diffraction, scanning electron microscopy, dynamic light scattering and FT-IR spectroscopy were used to characterize the resulting powders. Detailed investigations revealed that the optimal LaF₃ host nano-material was obtained when NH₄F was used as a fluoride source in the presence of EDTA at pH = 5. Furthermore, photoluminescence spectra showed an intense double emission peak at 289 and 302 nm for cerium-doped LaF₃ nanocrystals excited at 253 nm, which was assigned to the well-known 5d→4f (²F_5/2 and ²F_7/2) transitions of Ce³⁺ levels due to luminescence center mechanism. The experimental results indicate that the synthesized LaF₃:0.05Ce powders with a band gap of 5.3 eV are promising phosphors for high density scintillators.     

锁骨下动脉闭塞机械再通的方法研究

目的研究锁骨下动脉闭塞血管内机械再通方法和疗效。方法选择３２例症状性锁骨下动脉闭塞患者行血管内机械再通治疗，观察再通率及疗效。结果３２例锁骨下动脉闭塞患者中，用不同方法成功完成血管内机械再通后行血管内支架成形术，术后全部患者后循环缺血症状和上肢缺血症状明显改善。结论采用适当方法行机械再通治疗锁骨下动脉闭塞安全、可行。     

Rheology of natural fibers thermoplastic compounds: Flow length and fiber distribution

The presented study investigates the flow length and the corresponding fiber content distribution in the injection‐moulded natural fiber reinforced thermoplastics and its relation to fiber type and processing parameters such as injection pressure, temperature, injection rate and mould tempering by increasing die temperature. In this research, polypropylene compounds with nominally 30 wt % hemp and sisal fibers are investigated. The influence of the injection pressure (500 and 1000 bar), melt temperature (180°C, 200°C, and 220°C), and die temperature (23°C and 80°C) on the fiber content distribution all over the sample is investigated. An increasing linear trend of fiber content along the spiral length is observed as an evidence of a fiber/polymer multiflow system. A pattern for fiber content distribution with respect to the fiber length along the injected spiral can be distinguished, where the longer fibers are usually found at the end of the injected part and the shorter fibers remain near mould entrance point. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39861.     

鼻肠减压管插入技术及其在小肠梗阻治疗中的应用

目的探讨鼻肠减压管插入技术及在治疗小肠梗阻中的作用。方法作为主要治疗方法或术前胃肠道减压术在１０例急性小肠梗阻患者中实施了鼻肠减压管插入治疗。治疗在X线透视下实施,鼻肠减压导管经一侧鼻孔插入,在患者体位的配合和配套导丝的引导下,将鼻肠减压管插入至十二指肠屈氏韧带附近或更远处的小肠。结果全部病例鼻肠减压管均顺利通过幽门插入预定位置,平均操作时间１６min（１０～３５min）,经导管治疗后所有患者腹痛、腹胀、呕吐等症状均有不同程度缓解,其中４例（单纯性肠粘连）症状完全消失,２周后拔除导管;３例患者转手术治疗;３例放弃进一步治疗。在插管过程中未出现消化道出血、穿孔等与操作相关的并发症。结论在X线透视下鼻肠减压管插入相对简单,耗时短,在手术前的胃肠减压和治疗单纯粘连性肠梗阻的作用上效果明显,值得采用     

经皮血管内支架治疗锁骨下动脉狭窄性疾病

目的探讨应用血管内支架治疗锁骨下动脉狭窄或闭塞性疾病的疗效。方法回顾分析１０例１１支锁骨下动脉狭窄或闭塞病变行血管内介入治疗的临床资料。结果１０例８支锁骨下动脉狭窄病变（狭窄率大于７０％）成功置入支架,３支闭塞锁骨下动脉中１支成功置入支架,２支闭塞锁骨下动脉未能开通。７例经股动脉置入支架,１例经肱动脉逆行置入支架。锁骨下动脉支架成功置入后肱动脉及桡动脉搏动良好,伴有盗血现象的５例患者症状消失。随访２～２４个月发现１例锁骨下动脉支架置入后９个月近年来血管腔内技术发展迅速,已成为动脉狭窄和闭塞性疾病的重要治疗手段之一。锁骨下动脉狭窄或闭塞是常见的阻塞性颅外脑血管病,不仅可引起上肢缺血症状,若闭塞发生在锁骨下动脉近端,可致同侧椎动脉血流逆流至锁骨下动脉远端供应患侧上肢,引起椎－基底动脉供血不足症状,谓锁骨下动脉盗血综合征（subclavian steal syndrome ,SSS）。为探讨应用血管内支架治疗锁骨下动脉狭窄或闭塞性疾病的疗效,我院于２００４年６月至２００７年４月对１０例锁骨下动脉狭窄或闭塞患者进行了治疗,现报道如下。１材料与方法１．１材料１．１．１临床资料本组１０例患者中男９例,女１例。年龄４５～７５岁,平均６６岁。单纯左锁骨下动脉病变７例（闭塞３例,狭窄４例）,单纯右锁骨下动脉狭窄２例,双锁骨下动脉狭窄１例。９例患者患肢动脉压比对侧低２０mmHg 以上,１例患者双侧锁骨下动脉狭窄无明显血压差。８例上肢有感觉异常伴脉搏减弱或无脉,７例有长期头晕病史,５例经颅多普勒超声检查（TCD）显示有椎动脉逆流。临床诊断动脉硬化９例,病理诊断大动脉炎１例。１例合并右肾动脉闭塞,１例合并对侧椎动脉重度狭窄,２例合并一侧颈内动脉重度狭窄。１．１．２使用材料与设备本组选择３种类型的镍钛合金自膨支架,有Protege（EV３,美国）７枚,Precise RX（Cordis,美国）１枚,Maris（Invatec,意大利）１枚。直径８～１０mm,长度４～６cm。使用血管造影设备为西门子AXIOM ARTIS FA DSA系统。１．２介入方法１．２．１术前血管造影采用Seldinger技术行股动脉穿刺,置入５F导管鞘。用５F猪尾导管、猎人头管、西蒙管或单弯管行主动脉弓及全脑DSA,明确病变血管的部位、形态、范围、侧支循环及其他脑血管供血情况,测量血管狭窄或闭塞的程度与长度,以便制订手术方案,选择合适的血管支架。对盗血患者行椎动脉造影时可观察到整个盗血过程１．２．２血管内支架成形术采用Seldinger技术行股动脉穿刺,置入８F导管鞘。将８F导引管与“y”阀、三通、压力盐水袋连接并排气,在黑泥鳅加硬交换导丝引导下,将导引管置于病变锁骨下动脉近端,送入导丝并越过狭窄段至远端,选择直径８mm、长４cm球囊（Cordis,美国）沿导丝送入狭窄段,用压力泵在６～１２atm下扩张１～２次,每次３０s左右,间隔１～２min。撤出球囊导管,将支架递送系统再狭窄,后再置入１枚支架,血管开通良好。１例患者双侧锁骨下动脉狭窄同时置入２枚支架后２个月突发脑出血死亡。结论应用血管内支架治疗锁骨下动脉狭窄或闭塞是一种微创、安全、有效的治疗方法,有望成为主要的治疗手段