氨基糖甙类抗生素的体外抗生素后效应研究

目的 观察氨基糖甙类抗生素庆大霉素(GN)、奈替米星(NTL)和阿米卡星(AMK)的体外抗生素后效应(PAE)。方法 应用AVANTAG全能自动化微生物分析仪用光密度测定法测定GN、NTL和AMK对4种共20株受试菌的PAE。结果 3种氨基糖甙类抗生素对受试革兰氏阳性球菌和革兰氏阴性杆菌均产生明显的PAE,亚抑菌浓度(1/2 MIC)时也存在PAE, PAE值随药物浓度的增加而增大(P<0.05),表现出强的浓度依赖性,不同菌株产生不同的PAE。结论 PAE 的存在提示设计氨基糖甙类抗生素给药方案时可减少给药次数,延长用药间歇,维持药物疗效,从而减轻毒副作用。     

20种抗菌药物对金黄色葡萄球菌抗生素后效应的研究

目的 研究20 种抗菌药物对医院感染主要致病菌——金黄色葡萄球菌的抗生素后效应(PAE)。方法 采用光密度法测定PAE, 以实验组与对照组细菌恢复对数生长期时间差计算PAE。结果 在亚MIC 浓度时β-内酰胺类抗生素对金黄色葡萄球菌的PAE 很短, 而大环内酯类、氟喹诺酮类、氨基糖甙类PAE 已很明显, 尤其大环内酯类PAE 可达2 h 左右。随药物浓度增加, PAE 均有增加的趋势。在4 倍MIC 时, 青霉素类、碳青霉烯类PAE 明显延长, 而头孢菌素类PAE 仍相对较短;大环内酯类、氨基糖甙类、氟喹诺酮类药物和磷霉素PAE 显著增加, 并长于β-内酰胺类PAE。结论 抑制蛋白质和DNA 合成的抗菌药物及磷霉素对金黄色葡萄球菌的PAE 较明显, 要长于β-内酰胺类抗生素的PAE, 可能与PAE 产生机制不同有关。     

伊米培南'西司他丁与帕那培南'西司他丁抗生素后效应的研究

目的 研究伊米培南'西司他丁(商品名:泰宁)和帕那培南'西司他丁(商品名:卡贝宁)对4种临床常见致病菌的抗生素后效应(PAE)。方法 受试菌包括金黄色葡萄球菌、粪肠球菌、大肠埃希氏菌和绿脓假单胞菌, 用稀释法清除抗生素, 采取光密度法测定PAE。结果 泰宁和卡贝宁对G⁺球菌和G^-杆菌的PAE 均很明显, 且呈浓度依赖性;卡贝宁的PAE 显著长于泰宁。结论 泰宁和卡贝宁对临床常见致病菌均显示较长的PAE, 当设计个体化给药方案时应考虑PAE 因素。     

舒巴克坦对头孢哌酮体外抗生素后效应的影响

目的 考察合用β-内酰胺酶抑制剂舒巴克坦(SBT)前后头孢哌酮(CPZ)对4种致病菌抗生素后效应(PAE)的变化。方法 采用特异性 β一内酰胺酶鉴定试剂Nitrocefin挑选大肠埃希氏杆菌、金黄色葡萄球菌、变形杆菌和绿脓假单胞菌的产酶菌株,用比浊法测定受试菌株在不同CPZ浓度时的PAE值。结果 合用 SBT后,CPZ对产酶菌株的PAE均有不同程度的延长,低浓度时(1/2,1倍MIC)PAE增加更明显(P<0.05)。结论 合并CPZ和SBT的给药方案对治疗产β-内酰胺酶菌株引起的感染有利,尤其在体内药物浓度较低时,合并用药可以更长时间地抑制细菌生长。     

6种β-内酰胺类抗生素对G-杆菌的PAE 特点

目的 对比研究6 种β^-内酰胺类抗菌药物泰宁(TIN)、卡贝宁(CBN)、哌拉西林(PIP)、美洛西林(MZL)、头孢哌酮(CPZ)和头孢地嗪(CDZM)对2 种G^-杆菌大肠埃希氏菌和绿脓假单胞菌的抗生素后效应(PAE)。方法 采用AVANTAGE 全自动分析仪, 应用光密度法测定PAE。结果与结论 美洛西林对大肠埃希氏菌的PAE 为负值或零, 对绿脓假单胞菌的PAE很小, 仅在4MIC 时PAE 达1h 左右;哌拉西林对大肠埃希氏菌和绿脓假单胞菌的PAE 均很小, 即使在4MIC 时PAE 也仅有0.3h 左右。在4MIC 以下时, PAE 与浓度依赖性不甚明显。头孢哌酮和头孢地嗪除了在4MIC 时对大肠埃希氏菌的PAE 可达1h 外, 其余PAE 均很短,甚至没有, 但随着抗菌药物浓度的增加, PAE 显著增加(P<0.05), 呈现部分浓度依赖性, 提示在较高浓度下可望产生相对明显的PAE。一般β^-内酰胺类抗菌药物对G^-杆菌PAE 较小,而泰宁和卡贝宁则较长。泰宁和卡贝宁的PAE 要显著长于其它4 种抗菌药物(P<0.05), 两药对大肠埃希氏菌和绿脓假单胞菌的PAE 均可达到1~3h, 同时卡贝宁的PA E 要显著长于泰宁。即使在1 倍MIC 时, PAE 亦显著长于其它4 种药物, 而在4 倍MIC 时则更长。两药对G^-杆菌的PAE 在1/2 至4 倍MIC 浓度间呈显著的浓度依赖性。提示泰宁和卡贝宁可能具有与其它β^-内酰胺类抗菌药物不同的PAE 产生机理。     

美洛西林与头孢呋肟治疗淋病的对照研究

目的 对新药美洛西林以头孢呋肟为对照药, 观察治疗淋病的临床疗效。方法 选择临床诊断为无合并症淋病成年患者, 采用随机对照观察方法。结果 美洛西林组的痊愈率(75%)略高于头孢呋肟组(70%)、有效率均为100%;不良反应发生率较低、症状轻微。结论 美洛西林可作为治疗淋病的有效而安全的抗生素。     

阿莫西林与庆大霉素或奈替米星联合应用PAE的比较

目的 阿莫西林(AMPC)与庆大霉素(GM)或奈替米星(NTL)联合应用抗生素后效应(PAE)的比较。方法 应用光密度法测定PAE。结果 AMPC单用时对金黄色葡萄球菌和粪肠球菌有较长的PAE,对大肠埃希氏菌PAE甚小;GM和NTL单用对G'球菌的PAE亦很明显,对大肠埃希氏菌PAE稍短,但比单用AMPC要长。NTL的PAE比GM长,可能与受试菌对NTL敏感性高于GM有关。三种药物PAE均有随药物浓度增加而延长的趋势。AMPC与4倍MIC的GM或NTL联用时对受试菌的PAE均呈协同或相加效应;对G⁺球菌的联合PAE比G^-杆菌明显延长;AMPC与NTL的联合PAE长于与GM联合的PAE。结论 AMPC与GM或NTL联用时延长给药间隔,仍可维持强大的抗菌活性,减轻不良反应,AMPC与NTL联用优于与GM联用。     

原子力显微镜观察头孢美唑抗生素后效应期间大肠埃希菌形态学特征

目的: 通过应用原子力显微镜对头孢美唑体外抗生素后效应(PAE) 期间E. coliATCC25922 的形态学观察, 深入探讨其抗生素后效应形成机制。方法: 采用菌落计数法测定头孢美唑对E. coli 的PAE的同时, 应用原子力显微镜观察体外PAE 期间4MIC 、128 MIC 的头孢美唑不同时间点E. coli. ATCC25922 的形态学变化。结果: 菌落计数法测定4MIC 、128 MIC 头孢美唑的体外PAE 分别为-0. 03 h和3. 65 h 。原子力显微镜结果表明低浓度(4 MIC)时细菌呈丝状体, 高浓度(128 MIC) 时细菌呈球状体, 而且在菌落计数法所测定的PAE 之后仍有细菌形态学改变。结论: 不同浓度的头孢美唑PAE 期间E. coli 菌体形态呈现不同的变化, 从而显示了不同浓度的头孢美唑PAE 期间对E. coli 具有不同的作用靶位。     

反义寡核苷酸-聚乙烯亚胺纳米微粒逆转耐甲氧西林金黄色葡萄球菌耐药性的研究

目的 以聚乙烯亚胺(polyethyleneimine, PEI) 为载体, 将硫代寡聚脱氧核苷酸(PS-ODNs) 转染到耐甲氧西林金黄色葡萄球菌(methicillin resistant staphylococcus aureus, MRSA) 体内, 通过药效学观察PS-ODNs 逆转MRSA 对β-内酰胺类抗生素的耐药性。方法 制备PEI 与PS-ODNs 结合的纳米微粒(PEI-ODNs 纳米微粒) ;PEI-ODNs 纳米微粒的粒径分析及结合率的测定;平板克隆形成实验计数菌落数(CFU) ;微量法测定细菌生长曲线;液体稀释法测定细菌的最小抑菌浓度(MIC)。结果 PEI-ODNs 纳米微粒的粒径为(85±22) nm, PEI与PS-ODNs 的结合率最高为(97.3±1.1) %。含苯唑西林(6 mg L) 的M-H 琼脂板上, 30 μg/mL 的PEI-ODNs 纳米微粒组MRSA 的菌落数为6.4×108 mL, 而空白对照组的菌落数为3.3×109 mL,二者相比给药组菌落数明显减少, 差异具有统计学意义(P<0.01), 而其他对照组与空白对照组比较差异无统计学意义。实验结果显示PEIODNs纳米微粒组的苯唑西林对MRSA 生长有抑制作用, 30 μg/mL 的PEI-ODNs 纳米微粒可将苯唑西林对MRSA 最小抑菌浓度由1 024 μg/mL 降低至16 μg/mL。结论 PEI 与PS-ODNs 的结合率很高且粒径较小, PS-ODNs 可以部分逆转MRSA 对β-内酰胺类抗生素的耐药性。药效学结果显示PEI 可以有效地将反义寡核苷酸转入MRSA 体内, 可考虑将其作为反义寡核苷酸进入细菌的载体。     

脱氧核酶抑制耐甲氧西林金黄色葡萄球菌耐药基因的表达

目的 探讨抑制耐甲氧西林金黄色葡萄球菌(MRSA)耐药基因blaR1 表达的脱氧核酶对MRSA耐药性的影响。 方法 以耐药基因blaR1 的mRNA为靶点, 设计合成脱氧核酶DrzB, 导入细菌后通过平板克隆形成实验观察DrzB 对MRSA 细菌耐药性的影响, 通过RT-PCR 观察DrzB 对耐药基因blaR1表达的抑制作用。 结果 加入DrzB 后培养的MRSA,在含苯唑西林(6 mg·L^-1)的M-H 琼脂培养基表面生长的菌落单元计数低于对照组(P <0.01), blaR1的mRNA 表达水平也较对照组降低(P <0.01)。 结论 导入以blaR1 的mRNA 为靶基因的DrzB 阻断耐药基因表达, 可以部分恢复MRSA 的抗生素敏感性。脱氧核酶DrzB 是一种特异性的、有效的基因治疗剂。     

Effects of Post-weld Heat Treatment on Microstructure,Mechanical Properties and the Role of Weld Reinforcement in 2219 Aluminum Alloy TIG-Welded Joints

In as-welded state, each region of 2219 aluminum alloy TIG-welded joint shows diff erent microstructure and microhardness due to the diff erent welding heat cycles and the resulting evolution of second phases. After the post-weld heat treatment, both the amount and the size of the eutectic structure or θ phases decreased. Correspondingly, both the Cu content in α-Al matrix and the microhardness increased to a similar level in each region of the joint, and the tensile strength of the entire joint was greatly improved. Post-weld heat treatment played the role of solid solution strengthening and aging strengthening. After the post-weld heat treatment, the weld performance became similar to other regions, but weld reinforcements lost their reinforcing eff ect on the weld and their existence was more of an adverse eff ect. The joint without weld reinforcements after the post-weld heat treatment had the optimal tensile properties, and the specimens randomly crack in the weld zone.     

The First Phase of the SRIF Industrialized Base in ＂West Area＂ Has Been Put into Operation

After nearly two years＇ tense construction, the first phase of industrialized base of Shenyang Research Institute of Foundry （SRIF）, located at the Tiexi Casting and Forging Industrial Park in the west of Tiexi District, has now been completed and formally put into operation.     

Theoretical Analysis for the Motion and Temperature of Melt Droplets in Spray Degassing Process

The motion of melt droplets in spray degassing process was analyzed theoretically. The height of the treatment tank in spray degassing process could be determined by the results of theoretical calculation of motion of melt droplets. To know whether the melt droplets would solidify during spraying process, the balance temperature of melt droplets was also theoretically analyzed. Then proof experiments for theoretical results about temperature of melt droplets were carried. In comparison, the experimental results were nearly similar to the calculation results.     

Growth Kinetics of Single Inclusion Particle in Molten Melts

On the basis of the single-particle framework, a new theory on inclusion growth in metallurgical melts is developed to study the kinetics of inclusion growth on account of reaction and collision. The studies show that the early growth of inclusion depends on reaction growth and Brawnian motion collision, and where the former is decisive, the late growth depends on turbulence collision and Stokes＇ collision, and where the former is dominant; collision growth is very quick during the smelting process, lessened in the refining process, but nearly negligible in the continuous casting process.     

An Easy Way to Quantify the Adhesion Energy of Nanostructured Cu/X(X=Cr,Ta,Mo,Nb,Zr) Multilayer Films Adherent to Polyimide Substrates

An approach based on film buckling under simple uniaxial tensile testing was utilized in this paper to quantitatively estimate the interfacial energy of the nanostructured multilayer films(NMFs) adherent to flexible substrates. The interfacial energies of polyimide-supported NMFs are determined to be *5.0 J/m2 for Cu/Cr, *4.1 J/m2 for Cu/Ta,*2.8 J/m2 for Cu/Mo, *1.1 J/m2 for Cu/Nb, and *1.2 J/m2 for Cu/Zr NMFs. Furthermore, a linear relationship between the adhesion energy and the interfacial shear strength is clearly demonstrated for the Cu-based NMFs, which is highly indicative of the applicability and reliability of the modified models.     

High-Speed Friction Stir Welding of SiC_p/Al–Mg–Si–Cu Composite

A 17 vol% SiCp/Al–Mg–Si–Cu composite plate with a thickness of 3 mm was successfully friction stir welded(FSWed) at a very high welding speed of 2000 mm/min for the first time. Microstructural observation indicated that the coarsening of the precipitates was greatly inhibited in the heat-affected zone of the FSW joint at high welding speed, due to the significantly reduced peak temperature and duration at high temperature. Therefore, prominent enhancement of the hardness was achieved at the lowest hardness zone of the FSW joint at this high welding speed, which was similar to that of the nugget zone. Furthermore, the ultimate tensile strength of the joint was as high as 369 MPa, which was much higher than that obtained at low welding speed of 100 mm/min(298 MPa). This study provides an effective method to weld aluminum matrix composite with superior quality and high welding efficiency.     

新型的治疗阿尔茨海默氏症药物(1-二甲基磷酰基-2,2,2-三氯)-乙基-1-醇烟酸醋对体外神经细胞的作用

目的: 观察本实验室合成的一种治疗阿尔茨海默氏症(AD)的药物(1-二甲基磷酰基-2, 2, 2 -三氯)-乙基^-1-醇烟酸醋(NMF),对体外培养的皮层神经细胞活性的影响以及对海人藻酸(KA)所致的神经损伤的保护作用。方法: 采用体外培养皮层神经元的方法,解剖分离 15 d胚胎小鼠皮层神经细胞, 接种于 96孔板,48 h 后加药并培养 72 h,以 MIT 法 观察 NMF 对小鼠皮层神经细胞活性的影响;同时将接种于 24 孔板的细胞预先给予 NMF,d 3 时加或不加KA处理后,以台盼蓝染色鉴别并计数死、活细胞,可得出细胞的存活率。结果: NMF 明显促进胎鼠皮层神经元活性,其中 NMF1、0. 1、10nmol·L^-1促进神经元活性增殖率分别高达 34.7%、37.4%、36. 7%, NMF 明显促进正常胎鼠皮层神经元存活卒,与对照组比较,10nmol·L^-1 NMF 对皮层神经元的存活率分别提高 39.3%、73.5%。 NMF能显著 对抗 KA 所致的神经元损伤,与 KA 损伤组相比, NMF0.1、10、10nmol·L^-1对损伤皮层神经元的保护率分别为 77.30%、80.10%、84.15%。结论: NMF 明 显促进胎鼠皮层神经元的洁性、提高正常皮层神经元,的存活卒,并能有效地保护KA所致的神经元损伤,提示 NMF 是一种很有潜力的治疗 AD 的药物。     

A STUDY OF TEMPERATURE-DEPENDENT VALENCE BOND STRUCTURE OF TITANIUM

On the basis of energy and shape method for the determination of the valence bond (VB) structures of crystal, the valence bond structure of titanium is redetermined at room temperature and calculated in the whole temperature range of 0-1943K. The outer shell electronic distribution of Ti is e_c~(2.9907) · (s_c~(0.4980) d_c~(2.4927)) ef1.0093 in crystal. The temperature dependences of the VB structures of hcp and bcc phases are the same. The VB structures of hcp and bcc phases monotonically increase or decrease with the increase in temperature, but show discontinuous changes at the phase-transformation temperature 1155K.     

Structural Optimization of Electromagnetic Swirling Flow in Nozzle of Slab Continuous Casting

During the slab continuous casting process, the flow field of molten steel in the mold plays a decisive role in the quality of the slab. In this paper, electromagnetic swirling flow in nozzle technology is proposed to control the flow field in mold.This technology can drive molten steel to rotate inside the submerged entry nozzle by electromagnetic force, thereby controlling the flow field. This research shows that it can reduce the impact of molten steel on the bottom of nozzle and partly reduce the negative pressure at the upper part of nozzle outlet which is even eliminated by optimizing the structure and angle of nozzle. The area of heat flux of the mold wall becomes larger, and the crest value of heat flux gets lower than that without swirling in nozzle and any nozzle optimization. The meniscus fluctuates smoothly, and the flow velocity at the top surface is within a reasonable range. The temperature field distribution in the mold is uniform which was beneficial to the growth of equiaxed crystal and decreased element segregation.     

Effect of Rare Earth Doping on Impedance,Modulus and Conductivity Properties of Multiferroic Composites:0.5(BiLa_xFe_(1-x)O_3)–0.5(PbTiO_3)

The Lanthanum-doped bismuth ferrite–lead titanate compositions of 0.5(Bi LaxFe1-xO3)–0.5(Pb Ti O3)(x = 0.05,0.10,0.15,0.20)(BLxF1-x-PT) were prepared by mixed oxide method.Structural characterization was performed by X-ray diffraction and shows a tetragonal structure at room temperature.The lattice parameter c/a ratio decreases with increasing of La(x = 0.05–0.20) concentration of the composites.The effect of charge carrier/ion hopping mechanism,conductivity,relaxation process and impedance parameters was studied using an impedance analyzer in a wide frequency range(102–106Hz) at different temperatures.The nature of Nyquist plot confirms the presence of bulk effects only,and non-Debye type of relaxation processes occurs in the composites.The electrical modulus exhibits an important role of the hopping mechanism in the electrical transport process of the materials.The ac conductivity and dc conductivity of the materials were studied,and the activation energy found to be 0.81,0.77,0.76 and 0.74 e V for all compositions of x = 0.05–0.20 at different temperatures(200–300 °C).