两种血液净化方式对维持性血液透析伴高血压患者血压的影响

目的探讨血液灌流与透析对维持性血液透析伴高血压患者的血压、血浆内皮素-1(ET-1)及瘦素(Lep的影响,并对其机制作初步分析。方法选取陕西省人民医院2016年3月～2017年2月行维持性血液透析伴高血压患者94例作为研究对象,根据血液透析方式不同将患者分为观察组与对照组,每组各47例,观察组采用血液灌流联合常规透析,对照组采用常规血液透析。比较两组患者血压水平、实验室血液指标、机体矿物质、骨代谢指标水平及生活质量变化情况。结果对照组收缩压、舒张压治疗4、8、12周后稍低于治疗前(P>0.05),但观察组明显低于治疗前(P<0.05);治疗后同一时期,观察组收缩压、舒张压明显低于对照组(P<0.05);对照组治疗12周后ET-1、Lep水平明显高于治疗前(P<0.05),观察组治疗12周后ET-1、Lep水平明显低于治疗前(P<0.05);治疗后同一时期,观察组ET-1、Lep水平明显优于对照组(P<0.05)。治疗后,观察组患者C反应蛋白(CRP)、白介素-6(IL-6)指标水平下降幅度明显大于对照组(P<0.05);观察组患者治疗后Ca明显下降,P、PINP明显上升(P<0.05);观察组患者治疗后FGF-23、iPTH、Ca、P、β-CTX、PINP指标水平较治疗前均明显下降(P<0.05);观察组治疗后患者躯体功能、角色功能、情绪功能、认知功能、社会功能评分均明显高于对照组(P<0.05)。结论血液灌流联合常规透析相对于常规血液透析更能有效降低维持性血液透析伴高血压患者的血压水平,并改善血浆ET-1及Lep水平,但血液灌流联合常规透析对患者机体矿物质、骨代谢指标存在一定影响,在治疗过程中需要对患者采取相应预防措施。

miR-26a对脑梗死大鼠血管生成的调节作用及其机制

目的研究miRNA-26a在大鼠脑梗死中的作用以及miRNA-26a对脑梗死大鼠血管生成的影响。方法将16只SPF级雄性SD大鼠随机分为假手术组和脑梗死模型组,采用MCAO法建立大鼠脑梗死模型,TTC法检测大鼠脑梗死体积,Garcia法评估大鼠神经功能。对体外培养和转染的大鼠脑微血管内皮细胞(BMEC)分为:正常组、miR-26a mimic组、miR-26a inhibitor组、mimic+VEGF inhibitor组和体外氧葡萄糖剥夺(OGD)组。正常组为正常大鼠脑微血管内皮细胞;miR-26a mimic组BMEC细胞转染miRNA-26a模拟物;miR-26a inhibitor组BMEC细胞转染miRNA-26a抑制剂;mimic+VEGF inhibitor组BMEC细胞转染miRNA-26a模拟物并添加VEGF抑制剂Sorafenib Tosylate;OGD组BMEC细胞建立体外氧葡萄糖剥夺模型。Trizol法提取细胞中的总RNA,RT-PCR法检测miRNA-26a的表达,MTT法检测细胞增殖和管壁形成情况,蛋白质免疫印迹分析检测VEGF、FGF和Ang蛋白的表达水平。结果与假手术组相比,模型组大鼠脑组织中miR-26a的表达显著上调(P<0.01)。体外的细胞培养中,与正常组相比,OGD组miR-26a的表达显著上调(P<0.01)。与正常组比较,miR-26a mimic组BMEC细胞凋亡率显著降低(P<0.01),小管的形成和长度以及细胞增殖率均显著增加(均P<0.01);与miR-26a mimic组相比,miR-26a inhibitor组中细胞凋亡率显著升高(P<0.01),小管的形成和长度以及细胞增殖率均显著降低(均P<0.01)。与正常组相比,miR-26a mimic组VEGF、FGF和Ang蛋白的表达水平均显著上调(P<0.01);与miR-26a mimic组相比,miR-26a inhibitor组VEGF、FGF和Ang蛋白的表达水平显著下调(P<0.01)。与miR-26a mimic组相比,mimic+VEGF inhibitor组小管的形成受到显著抑制(P<0.01),细胞的相对数目显著减少(P<0.01)。结论miRNA-26a通过调节VEGF的表达影响脑梗死大鼠血管内皮功能及血管的重建和细胞的增殖,其有望成为脑梗死治疗的生物靶标之一。

急性多发性脑梗死患者血栓形成与Cys C、血浆MIF相关性分析

目的:探讨急性多发性脑梗死(acute multiple brain infarction,AMBI)患者并发下肢静脉血栓与Cys C、血浆MIF相关性,并分析其对患者预后的影响,为AMBI患者并发下肢静脉血栓的临床诊治提供参考。方法:选择156例AMBI患者作为研究对象,按照是否并发下肢静脉血栓将其分为对照组(n=96,多发性脑梗死患者)和观察组(n=60,多发性脑梗死并发下肢静脉血栓患者),比较两组患者血清胱抑素C(Cys-C)、巨噬细胞移动抑制因子(MIF)、同型半胱氨酸(Hcy)、基质金属蛋白酶9水平(MMP-9)水平,并分析其相关性;观察两组患者日常生活能力(Barthel指数)与神经功能缺损状况(NIHSS)差异。另将观察组患者按照入院3个月后改良Rankin量表评分将其分为预后不良组和预后良好组,分析两组患者的入院时血清Cys C、MIF、Hcy以及MMP-9水平差异。结果:与对照组相比,观察组患者入院时的血清Cys C、Hcy、MMP-9、MIF水平以及NIHSS评分均明显升高,Barthel指数明显降低(P<0.05)。而与预后良好组相比,预后不良组患者的血清Cys C、Hcy、MMP-9、MIF水平均明显升高(P<0.05)。血清Cys C、Hcy、MMP-9以及MIF水平与其呈现正相关,差异具有统计学意义(P<0.05)。结论:AMBI并发下肢静脉血栓患者血清Cys C、MIF水平相对较高,神经功能损伤以及日常生活能力较差,且血清Cys C、MIF水平的升高与患者预后不良关系密切。

Curcumin Synergizes with Cisplatin to Inhibit Colon Cancer through Targeting the MicroRNA-137-Glutaminase Axis

Objective:Colorectal cancer(CRC)is one of the most lethal and prevalent malignancies world-wide.Currently,surgery,radiotherapy and chemotherapy are clinically applied as common approaches for CRC patients.Cisplatin is one of the most frequently used chemotherapy drugs for diverse cancers.Although chemotherapeutic strategies have improved the prognosis and survival of cancer patients,development of cisplatin resistance has led to cancer recurrence.Curcumin,isolated from turmeric,has been used as an effective anti-cancer agent.However,the molecular mechanisms for curcumin-mediated cisplatin sensitivity of CRC have not been elucidated.

Radiation-hardened property of single-walled carbon nanotube film-based field-effect transistors under low-energy proton irradiation

Strong C-C bonds,nanoscale cross-section and low atomic number make single-walled carbon nanotubes(SWCNTs)a potential candidate material for integrated circuits(ICs)applied in outer space.However,very little work combines the simulation calculations with the electrical measurements of SWCNT field-effect transistors(FETs),which limits further understanding on the mechanisms of radiation effects.Here,SWCNT film-based FETs were fabricated to explore the total ionizing dose(TID)and displacement damage effect on the electrical performance under low-energy proton irradiation with different fluences up to 1×1015 p/cm2.Large negative shift of the threshold voltage and obvious decrease of the on-state current verified the TID effect caused in the oxide layer.The stability of the subthreshold swing and the off-state current reveals that the displacement damage caused in the CNT layer is not serious,which proves that the CNT film is radiation-hardened.Specially,according to the simulation,we found the displacement damage caused by protons is different in the source/drain contact area and channel area,leading to varying degrees of change for the contact resistance and sheet resistance.Having analyzed the simulation results and electrical measurements,we explained the low-energy proton irradiation mechanism of the CNT FETs,which is essential for the construction of radiation-hardened CNT film-based ICs for aircrafts.

Enhancement of radiation hardness of InP-based HEMT with double Si-doped plane

An anti-radiation structure of In P-based high electron mobility transistor(HEMT) has been proposed and optimized with double Si-doped planes. The additional Si-doped plane under channel layer has made a huge promotion in channel current, transconductance, current gain cut-off frequency, and maximum oscillation frequency of In P-based HEMTs. Moreover, direct current(DC) and radio frequency(RF) characteristic properties and their reduction rates have been compared in detail between single Si-doped and double Si-doped structures after 75-keV proton irradiation with dose of 5× 10^(11) cm^(-2),1× 10^(12) cm^(-2), and 5× 10^(12) cm^(-2). DC and RF characteristics for both structures are observed to decrease gradually as irradiation dose rises, which particularly show a drastic drop at dose of 5× 10^(12) cm^(-2). Besides, characteristic degradation degree of the double Si-doped structure is significantly lower than that of the single Si-doped structure, especially at large proton irradiation dose. The enhancement of proton radiation tolerance by the insertion of another Si-doped plane could be accounted for the tremendously increased native carriers, which are bound to weaken substantially the carrier removal effect by irradiation-induced defects.

Impact of symmetric gate-recess length on the DC and RF characteristics of InP HEMTs

We fabricated a set of symmetric gate-recess devices with gate length of 70 nm.We kept the source-to-drain spacing(L_(SD))unchanged,and obtained a group of devices with gate-recess length(L_(recess))from 0.4µm to 0.8µm through process improvement.In order to suppress the influence of the kink effect,we have done SiN_(X) passivation treatment.The maximum saturation current density(ID_(max))and maximum transconductance(g_(m,max))increase as L_(recess) decreases to 0.4µm.At this time,the device shows ID_(max)=749.6 mA/mm at V_(GS)=0.2 V,V_(DS)=1.5 V,and g_(m,max)=1111 mS/mm at V_(GS)=−0.35 V,V_(DS)=1.5 V.Meanwhile,as L_(recess) increases,it causes parasitic capacitance C_(gd) and g_(d) to decrease,making f_(max) drastically increases.When L_(recess)=0.8µm,the device shows f_(T)=188 GHz and f_(max)=1112 GHz.

Heterogeneous integration of InP HEMTs on quartz wafer using BCB bonding technology

Heterogeneous integrated InP high electron mobility transistors(HEMTs)on quartz wafers are fabricated successfully by using a reverse-grown InP epitaxial structure and benzocyclobutene(BCB)bonding technology.The channel of the new device is In_(0.7)Ga_(0.3)As,and the gate length is 100 nm.A maximum extrinsic transconductance gm,max of 855.5 mS/mm and a maximum drain current of 536.5 mA/mm are obtained.The current gain cutoff frequency is as high as 262 GHz and the maximum oscillation frequency reaches 288 GHz.In addition,a small signal equivalent circuit model of heterogeneous integration of InP HEMTs on quartz wafer is built to characterize device performance.

Influences of increasing gate stem height on DC and RF performances of InAlAs/InGaAs InP-based HEMTs

The T-gate stem height of In Al As/In Ga As In P-based high electron mobility transistor(HEMT) is increased from165 nm to 250 nm. The influences of increasing the gate stem height on the direct current(DC) and radio frequency(RF)performances of device are investigated. A 120-nm-long gate, 250-nm-high gate stem device exhibits a higher threshold voltage(Vth) of 60 m V than a 120-nm-long gate devices with a short gate stem, caused by more Pt distributions on the gate foot edges of the high Ti/Pt/Au gate. The Pt distribution in Schottky contact metal is found to increase with the gate stem height or the gate length increasing, and thus enhancing the Schottky barrier height and expanding the gate length,which can be due to the increased internal tensile stress of Pt. The more Pt distributions for the high gate stem device also lead to more obvious Pt sinking, which reduces the distance between the gate and the In Ga As channel so that the transconductance(gm) of the high gate stem device is 70 m S/mm larger than that of the short stem device. As for the RF performances,the gate extrinsic parasitic capacitance decreases and the intrinsic transconductance increases after the gate stem height has been increased, so the RF performances of device are obviously improved. The high gate stem device yields a maximum ft of 270 GHz and fmax of 460 GHz, while the short gate stem device has a maximum ft of 240 GHz and the fmax of 370 GHz.

Effect of defects properties on InP-based high electron mobility transistors

The performance damage mechanism of InP-based high electron mobility transistors(HEMTs) after proton irradiation has been investigated comprehensively through induced defects.The effects of the defect type, defect energy level with respect to conduction band ET, and defect concentration on the transfer and output characteristics of the device are discussed based on hydrodynamic model and Shockley–Read–Hall recombination model.The results indicate that only acceptorlike defects have a significant influence on device operation.Meanwhile, as defect energy level ETshifts away from conduction band, the drain current decreases gradually and finally reaches a saturation value with ETabove 0.5 eV.This can be attributed to the fact that at sufficient deep level, acceptor-type defects could not be ionized any more.Additionally,the drain current and transconductance degrade more severely with larger acceptor concentration.These changes of the electrical characteristics with proton radiation could be accounted for by the electron density reduction in the channel region from induced acceptor-like defects.

A comparative study on radiation reliability of composite channel InP high electron mobility transistors

This paper proposes a reasonable radiation-resistant composite channel structure for In P HEMTs.The simulation results show that the composite channel structure has excellent electrical properties due to increased modulation doping efficiency and carrier confinement.Moreover,the direct current(DC)and radio frequency(RF)characteristics and their reliability between the single channel structure and the composite channel structure after 75-ke V proton irradiation are compared in detail.The results show that the composite channel structure has excellent radiation tolerance.Mechanism analysis demonstrates that the composite channel structure weakens the carrier removal effect.This phenomenon can account for the increase of native carrier and the decrease of defect capture rate.

Optimization of terahertz monolithic integrated frequency multiplier based on trap-assisted physics model of THz Schottky barrier varactor

The optimization of high power terahertz monolithic integrated circuit (TMIC) is systemically studied based on the physical model of the Schottky barrier varactor (SBV) with interface defects and tunneling effect. An ultra-thin dielectric layer is added to describe the extra tunneling effect and the damping of thermionic emission current induced by the interface defects. Power consumption of the dielectric layer results in the decrease of capacitance modulation ration (Cmax/Cmin), and thus leads to poor nonlinear C–V characteristics. The proposed Schottky metal-brim (SMB) terminal structure could improve the capacitance modulation ration by reducing the influence of the interface charge and eliminating the fringing capacitance effect. Finally, a 215 GHz tripler TMIC is fabricated based on the SMB terminal structure. The output power is above 5 mW at 210–218 GHz and the maximum could exceed 10 mW at 216 GHz, which could be widely used in terahertz imaging, radiometers, and so on. This paper also provides theoretical support for the SMB structure to optimize the TMIC performance.

High frequency doubling efficiency THz GaAs Schottky barrier diode based on inverted trapezoidal epitaxial cross-section structure

A high-performance terahertz Schottky barrier diode(SBD)with an inverted trapezoidal epitaxial cross-sectional structure featuring high varactor characteristics and reverse breakdown characteristics is reported in this paper.Inductively coupled plasma dry etching and dissolution wet etching are used to define the profile of the epitaxial layer,by which the voltage-dependent variation trend of the thickness of the metal-semiconductor contact depletion layer is modified.The simulation of the inverted trapezoidal epitaxial cross-section SBD is also conducted to explain the physical mechanism of the electric field and space charge region area.Compared with the normal structure,the grading coefficient M increases from 0.47 to 0.52,and the capacitance modulation ratio(C^(max)/C_(min))increases from 6.70 to 7.61.The inverted trapezoidal epitaxial cross-section structure is a promising approach to improve the variable-capacity ratio by eliminating the accumulation of charge at the Schottky electrode edge.A 190 GHz frequency doubler based on the inverted trapezoidal epitaxial cross-section SBD also shows a doubling efficiency of 35%compared to that 30%of a normal SBD.

Impact of gate offset in gate recess on DC and RF performance of InAlAs/InGaAs InP-based HEMTs

A set of 100-nm gate-length In P-based high electron mobility transistors(HEMTs)were designed and fabricated with different gate offsets in gate recess.A novel technology was proposed for independent definition of gate recess and T-shaped gate by electron beam lithography.DC and RF measurement was conducted.With the gate offset varying from drain side to source side,the maximum drain current(I_(ds,max))and transconductance(g_(m,max))increased.In the meantime,fTdecreased while f;increased,and the highest fmax of 1096 GHz was obtained.It can be explained by the increase of gate-source capacitance and the decrease of gate-drain capacitance and source resistance.Output conductance was also suppressed by gate offset toward source side.This provides simple and flexible device parameter selection for HEMTs of different usages.

Enhancement of fMAX of InP-based HEMTs by double-recessed offset gate process

A double-recessed offset gate process technology for In P-based high electron mobility transistors(HEMTs)has been developed in this paper.Single-recessed and double-recessed HEMTs with different gate offsets have been fabricated and characterized.Compared with single-recessed devices,the maximum drain-source current(I_(D,max))and maximum extrinsic transconductance(g_(m,max))of double-recessed devices decreased due to the increase in series resistances.However,in terms of RF performance,double-recessed HEMTs achieved higher maximum oscillation frequency(f_(MAX))by reducing drain output conductance(g_(m,max))and drain to gate capacitance(C_gd).In addition,further improvement of fMAXwas observed by adjusting the gate offset of double-recessed devices.This can be explained by suppressing the ratio of C_(gd)to source to gate capacitance(C_gd)by extending drain-side recess length(Lrd).Compared with the single-recessed HEMTs,the f;of double-recessed offset gate HEMTs was increased by about 20%.

Extrinsic equivalent circuit modeling of InP HEMTs based on full-wave electromagnetic simulation

With the widespread utilization of indium-phosphide-based high-electron-mobility transistors(InP HEMTs)in the millimeter-wave(mmW)band,the distributed and high-frequency parasitic coupling behavior of the device is particularly prominent.We present an InP HEMT extrinsic parasitic equivalent circuit,in which the conductance between the device electrodes and a new gate-drain mutual inductance term L_(mgd)are taken into account for the high-frequency magnetic field coupling between device electrodes.Based on the suggested parasitic equivalent circuit,through HFSS and advanced design system(ADS)co-simulation,the equivalent circuit parameters are directly extracted in the multi-step system.The HFSS simulation prediction,measurement data,and modeled frequency response are compared with each other to verify the feasibility of the extraction method and the accuracy of the equivalent circuit.The proposed model demonstrates the distributed and radio-frequency behavior of the device and solves the problem that the equivalent circuit parameters of the conventional InP HEMTs device are limited by the device model and inaccurate at high frequencies when being extracted.

An electromagnetic simulation assisted small signal modeling method for InP double-heterojunction bipolar transistors

We present a convenient and practical electromagnetic(EM)assisted small-signal model extraction method for InP double-heterojunction bipolar transistors(DHBTs).Parasitic parameters of pad and electrode fingers are extracted by means of 3D EM simulation.The simulations with a new excitation scheme are closer to the actual on-wafer measurement conditions.Appropriate simulation settings are calibrated by comparing measurement and simulation of OPEN and SHORT structures.A simplerπ-type topology is proposed for the intrinsic model,in which the base-collector resistance Rμ,output resistance Rce are deleted,and a capacitance Cce is introduced to characterize the capacitive parasitic caused by the collector finger and emitter ground bar.The intrinsic parameters are all extracted by exact equations that are derived from rigorous mathematics.The method is characterized by its ease of implementation and the explicit physical meaning of extraction procedure.Experimental validations are performed at four biases for three InGaAs/InP HBT devices with 0.8×7μm,0.8×10μm and 0.8×15μm emitter,and quite good fitting results are obtained in the range of 0.1-50 GHz.

Characterization of low-resistance ohmic contacts to heavily carbon-doped n-type InGaAsBi films treated by rapid thermal annealing

Carbon-doped In Ga As Bi films on In P:Fe(100)substrates have been grown by gas source molecular beam epitaxy(GSMBE).The electrical properties and non-alloyed Ti/Pt/Au contact resistance of n-type carbon-doped In Ga As Bi films were characterized by Van der Pauw-Hall measurement and transmission line method(TLM)with and without rapid thermal annealing(RTA).It was found that the specific contact resistance decreases gradually with the increase of carrier concentration.The electron concentration exhibits a sharp increase,and the specific contact resistance shows a noticeable reduction after RTA.With RTA,the In Ga As Bi film grown under CBr4 supply pressure of 0.18 Torr exhibited a high electron concentration of 1.6×10^(21) cm^(-3) and achieved an ultra-low specific contact resistance of 1×10^(-8)Ω·cm^(2),revealing that contact resistance depends greatly on the tunneling effect.

miR-124与MAPK/ERK通路对调节脑梗死大鼠神经细胞凋亡的影响

目的:研究miR-124和MAPK/ERK途径对脑梗死大鼠神经细胞凋亡的影响及其可能的机制。方法:本研究将SD大鼠随机分为假手术组(Sham组)、模型组(CI组)、miR-124组(miR组)、脑梗死+miR-124组(CI+miR组)和脑梗死+MEK/ERK阻滞剂组(CI+U0126组),采用mNSS评分法评估大鼠神经功能损伤程度,采用TTC染色检测脑梗死体积,采用尼式染色检查脑组织的病理情况,采用TUNEL染色法检测大鼠脑神经细胞凋亡,TRIzol法提取总RNA,RT-PCR检测miR-124、ERK1和ERK2基因表达,蛋白质免疫印迹法检测Caspase-3、Bax、Bcl-2、MEK2和ERK1蛋白表达水平。结果:与Sham组和miR组相比,CI组、CI+miR组和CI+U0126组大鼠的脑梗死体积、mNSS评分和脑含水量均显著增加(P<0.01)。Sham组、miR组、CI+miR组和CI+U0126组大鼠的脑组织中尼式体的数量显著高于CI组,模型组大鼠的脑神经元结构被破坏且出现核移位和细胞坏死等病理变化;与Sham组和miR组相比,CI组大鼠中miR-124的表达水平显著降低(P<0.01),CI+miR组和CI+U0126组大鼠中miR-124的表达水平显著上调(P<0.01)。TUNEL染色结果显示,与模型组相比,CI+miR组和CI+U0126组大鼠中凋亡数量显著减少(P<0.01),ERK1和ERK2的mRNA相对表达水平均显著下调(P<0.01)。与模型组相比,CI+miR组和CI+U0126组大鼠脑组织中Caspase-3和Bax蛋白表达水平显著下调,Bcl-2蛋白的表达水平显著上调(P<0.01)。与模型组相比,CI+miR组和CI+U0126组大鼠脑组织中磷酸化的p-MEK-2和p-ERK1/2蛋白表达水平均显著下调(P<0.01)。结论:miR-124可能通过抑制MAPK/ERK信号通路的激活,减少脑梗死大鼠的神经细胞的凋亡,最终发挥保护作用。

生长分化因子11对甲醛诱导的海马神经细胞凋亡的影响

目的探讨生长分化因子11(GDF11)对甲醛诱导的海马神经(HT22)细胞毒性的影响。方法把HT22细胞分为对照组(细胞未做任何处理)、甲醛组(50、100、200μmol/L甲醛处理细胞)和GDF11+甲醛组(GDF11转染细胞后用100μmol/L甲醛处理)。细胞计数试剂盒(CCK8)法检测HT22细胞的活力;蛋白免疫印迹法检测HT22细胞凋亡相关蛋白Bax以及Bcl-2的变化;caspase-3活性检测试剂盒检测HT22细胞内caspase-3活性;DCFDA染色流式细胞仪检测HT22细胞中活性氧(ROS)水平。三组间比较采用单因素方差分析,组间两两比较采用LSD-t检验。结果与对照组比较,甲醛组HT22细胞活力(92.23±0.20比56.12±0.61)和Bcl-2蛋白表达(220.32±2.21比150.25±0.31)水平均降低,差异具有统计学意义(P均<0.05);而caspase-3活性(95.36±1.74比190.17±2.14)、Bax蛋白表达(132.19±1.21比150.17±1.06)和ROS水平(1099.32±75.47比2802.17±126.49)均升高,差异具有统计学意义(P均<0.05)。GDF11转染HT22细胞后,与甲醛组比较,GDF11+甲醛组HT22细胞活力升高(56.12±0.61比83.11±1.64),Bax蛋白表达(270.03±0.17比150.17±1.06)降低,Bcl-2蛋白表达(150.25±0.31比187.34±1.52)升高,caspase-3活性降低(190.17±2.14比105.31±4.12)和ROS水平降低(2802.17±126.49比1305.36±68.45),差异具有统计学意义(P均<0.05)。结论GDF11能够逆转甲醛对HT22细胞凋亡的诱导作用以及降低甲醛对HT22细胞ROS水平的增加作用,此机制对防治甲醛的神经毒性具有重要意义。