长程表面等离子体共振技术在检测大肠杆菌浓度中的应用研究

建立了一种基于长程表面等离子体共振技术检测大肠杆菌浓度的方法及系统。基于此,制备了能够产生长程表面等离子体共振效应的双层膜传感芯片,并在实验上将长程表面等离子体共振(LSPR)和传统表面等离子体共振(CSPR)两种生物传感器的性能进行了对比。结果表明LSPR生物传感器共振曲线的平均半高宽比CSPR传感器共振曲线的平均半高宽窄1.79倍,且其灵敏度是CSPR的2倍。由此,证实了基于LSPR的生物传感器对大肠杆菌浓度的改变更加敏感。此外,该方法分辨率高,试剂用量少,有效克服分界面所带来的影响,并能够对大肠杆菌进行实时检测。     

A localized surface plasmon resonance based immunosensor for the detection of casein in milk

In this research, a localized surface plasmon resonance (LSPR) immunosensor based on gold-capped nanoparticle substrate for detecting casein, one of the most potent allergens in milk, was developed. The fabrication of the gold-capped nanoparticle substrate involved a surface-modified silica nanoparticle layer (core) on the slide glass substrate between bottom and top gold layers (shell). The absorbance peak of the gold-capped nanoparticle substrate was observed at ～520 nm. In addition, the atomic force microscopy (AFM) images demonstrated that the nanoparticles formed a monolayer on the slide glass. After immobilizing anti-casein antibody on the surface, our device, casein immunosensor, could be applied easily for the detection of casein in the raw milk sample without a difficult pretreatment. Under the optimum conditions, the detection limit of the casein immunosensor was determined as 10 ng/mL. Our device brings several advantages to the existing LSPR-based biosensors with its easy fabrication, simple handling, low-cost, and high sensitivity.     

A localized surface plasmon resonance based immunosensor for the detection of casein in milk

In this research, a localized surface plasmon resonance (LSPR) immunosensor based on gold-capped nanoparticle substrate for detecting casein, one of the most potent allergens in milk, was developed. The fabrication of the gold-capped nanoparticle substrate involved a surface-modified silica nanoparticle layer (core) on the slide glass substrate between bottom and top gold layers (shell). The absorbance peak of the gold-capped nanoparticle substrate was observed at ∼520 nm. In addition, the atomic force microscopy (AFM) images demonstrated that the nanoparticles formed a monolayer on the slide glass. After immobilizing anti-casein antibody on the surface, our device, casein immunosensor, could be applied easily for the detection of casein in the raw milk sample without a difficult pretreatment. Under the optimum conditions, the detection limit of the casein immunosensor was determined as 10 ng/mL. Our device brings several advantages to the existing LSPR-based biosensors with its easy fabrication, simple handling, low-cost, and high sensitivity.     

High-birefringence dual-wavelength single-polarization photonic crystal fibre polarizing filter based on surface plasmon resonance

A dual communication band single-polarization photonic crystal fibre polarizing filter based on surface plasmon resonance is presented in this paper. Numerical simulation results demonstrate that the resonance strength of x- and y-polarized direction can reach 569.83 and 719.25?dB.cm^?1 simultaneously at the communication wavelength of 1.31 and 1.55?µm. By filling liquid analyte, the confinement loss of x- and y-polarized direction can simultaneously reach 831.7 and 580.53?dB.cm^?1 at the wavelength of 1.31 and 1.55?µm. Furthermore, when the fibre length L is equal to 700?µm, the peak value of the crosstalk can reach 493.86 and ?323.67?dB at the same time at the wavelength of 1.31 and 1.55?µm, and when the length of the fibre L is 400?µm, the bandwidths of the crosstalk better than 20?dB and less than ?20?dB are about 160 and 210?nm, respectively. These performances make it an ideal candidate for designing dual-band polarization filter equipment.     

密码子优化的牛精蛋白基因在大肠杆菌中的表达

以PCR的方法得到牛精蛋白基因的基因,去其内含子,得到牛精蛋白cDNA,克隆入原核表达载体pGEX-2T中,组装成表达载体pGEX-2T-PE,利用大肠杆菌偏好的编码精氨酸的密码子CGT将野生型牛精蛋白基因中编码精氨酸的稀有密码子（AGA或AGG）替换掉,通过基因合成得到密码子优化的牛精蛋白的基因,将其克隆入原核表达载体pGEX-2T中,组装成表达载体pGEX-2T-PS。将这两个表达载体分别转化入大肠杆菌表达菌株BL21中,经IPTG诱导,同样条件下,野生型牛精蛋白基因无法得到表达,密码子优化的牛精蛋白基因能够得到良好的表达,表达产物约占细菌总蛋白的18％,将表达蛋白纯化,进行DNA－蛋白结合实验,发现其能与DNA发生非特异性的结合。     

Transmittance spectrum of surface plasmon polariton based filter with asymmetric double-ring resonator and switch

The transmittance spectrum of a plasmonic filter has been numerically simulated by the two-dimension (2D) finite-difference time-domain method. The filter is composed of two Metal-Insulator-Metal waveguides and a resonator with two different rings. The results show that the rising edge of the asymmetric resonator is steeper than that of symmetric one at each pass band. By embedding the liquid crystal in the resonator, the filter can act as an electro-optical switch. These results show potential applications on nano-optical devices.     

离子强度对于牛精蛋白在大肠杆菌中的表达的影响

通过基因合成将大肠杆菌偏好的精氨酸密码子CGT取代野生型牛精蛋白基因中的稀有精氨酸密码子AGA和AGG,得到密码子优化的牛精蛋白基因,并将其克隆入原核表达载体pGEX-2T中,组装成表达载体pGEX-2T-PS。将这个表达载体转化入大肠杆菌表达菌株BL21中,经IPTG诱导,可得到一33kD融合蛋白表达带,首次成功地将牛精蛋白在大肠杆菌中进行了表达,但其表达量很低,约为总菌体蛋白的13％。增加表遂菌株培养液的离子强度,可将蛋白表达含量提高到28％,且蛋白表达量与离子强度呈正相关。纯化后的牛精蛋白可在体外条件下与DNA发生结合。     

Growth of silver nano-particle embedded in tellurite glass: Interaction between localized surface plasmon resonance and Er ions

In this paper we show a systematic study of the growth of silver nano-particles (NPs) embedded in an Erbium-doped tellurite glass with annealing time, aiming to a photoluminescence enhancement. The results indicate an improved or quenching of the photoluminescence due to an energy transfer mechanism in the coupling between NP’s electric dipoles and Er⁺³ transitions (⁴S_3/2 → ⁴I_15/2, ⁴F_9/2 → ⁴I_15/2 and ⁴I_13/2 → ⁴I_15/2).     

HIV-1核心蛋白的表达与纯化

将编码人I型免疫缺陷病毒(HIV1)核心蛋白p24gag的基因序列克隆到原核表达载体pET28(b)中,高效表达了N,C端融合His·Tagp24蛋白,所表达的重组p24蛋白占菌体总蛋白的46%。在变性条件下,使用NiNTA亲和层析法纯化了p24蛋白,纯度为94%。菌体中及纯化、复性后的目的蛋白均能与抗HIV1p24单克隆抗体发生特异性反应。用纯化的p24蛋白免疫小鼠,4周时小鼠血清抗p24抗体效价达1∶400。实验结果表明:大肠杆菌表达的HIV1p24蛋白纯化后可用作HIV1检测试剂的原料。     

新型高抗草甘膦N-乙酰转移酶基因的分离及其在大肠杆菌中的表达

利用草甘膦极端污染土壤总DNA,构建了元基因组文库,筛选到一个高抗草甘膦的N-乙酰转移酶(N-acetyltransferase,GAT)基因,并利用原核表达系统对该基因进行了功能鉴定,发现其在大肠杆菌BL21中能耐受高达300 mM的草甘膦.研究结果为进行N-乙酰化途径高抗草甘膦机理研究和新型高抗草甘膦转基因作物的开发提供了理论基础.     

Influence of the surface roughness on the properties of Au films measured by surface plasmon resonance and X-ray reflectometry

Thickness and refractive index of Au films thermally evaporated onto glass substrates and with an underlayer of Cr are determined from surface plasmon resonance. The results for the thickness are found to agree very well with those from X-ray reflectivity when a simple model of layers with flat interfaces is used. Plasmon propagation along thin films is influenced by radiative damping due to scattering from surface roughness. To study this influence the surface roughness of the glass substrate, Cr an Au layers are measured by X-ray reflectometry and the results used to introduce three intermediate layers with effective refractive indices and thicknesses corresponding to the roughness. Then Fresnel's equations are used to fit the reflectivity and to deduce the layer properties. It is found that the roughness affects to a great extent the optical parameters of the Au films even when it is smaller than 1 nm. In particular, the absolute value of real part of the dielectric constant decreases while its imaginary part increases when those effects are not taken into account.     

Finite Element Modelling and the Experimental Verification of Superplastic Forming

FEM analysis has proved to be a powerful investigative tool capable of encompassing all the aspects that characterise an SPF process. However, despite the high potential of FEM programs they do not allow one to directly and suitably obtain the thickness of a sheet product for high deformation values, as commonly occurs in SPF processes. Many papers have been published on finite element analysis of S.P.F. process but the question of calculus accuracy in thicknesses of a sheet product has not been directly investigated. This problem has been already considered by the authors in a previous study which proposed an algorithm to determine thicknesses for a specific application. The software set up starts out with the results of the FEM modelling, keeps track of the deformation undergone by each element of the mesh and calculates to a good approximation the thicknesses at the end of the forming. Although the original version of the algorithm could only be used for the application studied an updated version is introduced in this study that can be used for any case. In other words, the software generates the thickness profile at the end of the analysis independently of technological set up, item shape and type of simulation (3D and 2D). The proposed algorithm was tested with reference to the superplastic forming of an item of simple geometry beginning with a thin circular plate blocked at the edges and put under constant hydrostatic pressure on one side. The test material, made superplastic by means of a series of repeated laminations, was characterised using an alternative method to the traditional tension test. The results of the experiments are in good accordance with the numerical predictions both in terms of thickness distribution and forming times.     

人免疫缺陷病毒I型p24gag基因的重组与表达

将编码人Ｉ型免疫缺陷病毒（ＨＩＶ－１）衣壳蛋白的ｐ２４ｇａｇ基因片段，克隆到原核表达载体ｐＥＴ－１７ｂ的Ｔ７噬菌体启动子下游，构建成了重组表达质粒ｐＥＴ２４，并使ｐ２４ｇａｇ基因片段在大肠杆菌ＢＬ２１（ＤＥ３）中高效表达，产物为３０ｋＤａ的ｓ１９－ｐ２４融合蛋白，表达量占菌体总蛋白的３８．４％。重组ｐ２４蛋白均与抗ｐ２４单克隆抗体及ＨＩＶ－１阳性血清发生特异性反应，具有较好的抗原性。     

基于生物发光磁酶免疫的现场快速检测用便携式细菌检测仪(英文)

为了能够现场快速特异性检测大肠杆菌,研制了基于生物发光磁酶免疫的便携式检测仪,检测仪由光子计数单元、中央处理单元、温度控制单元和电源管理单元组成.温度控制单元可以提供恒定的温度37℃,适于培养和现场检测.提出一种改进的、将免疫磁珠与生物素化兔抗大肠杆菌抗体偶联的检测方法,能够一步直接测定大肠杆菌浓度.对浓度为23.00 CFU/mL～2.25×107CFU/mL的大肠杆菌菌液进行快速检测,仪表检测值与传统培养法结果在对数下呈良好的线性关系,相关系数为0.965 7,系统的检测灵敏度为0.478 7.对样品进行重复性测试,变异系数为4.48%.该集成了温度控制单元的检测仪便携、易于操作、检测成本低,将在食品卫生和安全、环境监测、疾病诊断等领域具有潜在的应用前景.     

高精度6inch F/5.4球面标准具结构研究与设计

193 nm光刻投影物镜光学元件面形精度为纳米级,因此要求检测精度为纳米到亚纳米级.在高精度的光学元件面形检测中,为了保证检测的精度,干涉仪标准球面镜的精度要优于λ/40.根据检测要求,设计了一种新的标准镜装卡结构.采用有限元方法分析了参考面在重力作用下的面形变化情况,其最大面变形变化峰谷(PV)值仅为4.88 nm,...     

镭普克的制备及对小鼠H22肝癌的抑制作用

报道重组别藻蓝蛋白(rAPC,镭普克)表达菌株的20L高密度发酵、镭普克制备及对小鼠H22肝癌抑制作用的实验结果。采用两步发酵法最终OD600为36．18,比一步发酵法的40．16值低,但镭普克表达率是后者的1．8倍,为30．24％,镭普克生物量提高1．62倍。亲合层析结合分子筛层析纯化后,镭普克纯度可达98．03％。对小鼠H22肝癌静脉注射剂量为50mg/kg／d,抑瘤率为62．2％。初步的免疫实验结果表明,镭普克对淋巴B细胞功能具有增强作用。结果提示镭普克大规模生产的潜力和临床应用的可能性。     

Modelling the fracture of concrete under mixed loading

A simple and efficient numerical procedure for mixed mode fracture of quasibrittle materials is shown: This technique predicts crack trajectories as well as load-displacement or load-CMOD responses. The model is based on the cohesive crack concept and uses the local mode I approach. Numerical results agree quite well with three experimental sets of mixed mode fracture of concrete beams; one from Arrea and Ingraffea, another from García, Gettu and Carol and from a nonproportional loading by the authors. In constrast to more sophisticated models, this method offers two major advantages: it requires only material properties measured by standardized methods and it can easily be implemented with general multipurpose finite element codes.     

牙鲆生长激素基因的克隆及其在大肠杆菌中的融合表达

采用逆转录聚合酶链式反应(RT-PCR)方法,从牙鲆(Paralichthys olivaceus)脑垂体总RNA中扩增出编码牙鲆生长素(GH)成熟肽基因序列。重组至融合表达载体pGEX-4T-3中,构建成牙鲆GH基因融合表达载体pGEX-gh,转化大肠杆菌BL21(DF3),筛选阳性克隆,IVIG诱导表达。经SDS-PAGE电泳显示在45kD处有特异的蛋白条带出现,该蛋白的表达量随诱导时间的延长而增加,3h达最高值,达到细胞总蛋白的18．3％。该融合蛋白在胞内主要以包涵体状态存在,经优化表达条件,成功地获得了可溶性的融合蛋白,经Glutathione Sepharase 4B凝胶纯化后用Western-blotting检测表明其为牙鲆生长激素,并通过酶联免疫吸附受体法证实其具有生物学活性。     

Preparation, characterisation and processing of carbon fibre/polyamide-12 composites for selective laser sintering

Aiming at developing carbon fibre/polyamide-12 (CF/PA) composite powders for manufacturing high-performance components by selective laser sintering (SLS), the preparation, characteristics and sintering process of the composite powders and mechanical properties of sintered components were studied. Surfaces of the carbon fibres were treated by the oxidation modification and coated with polyamide-12 through the dissolution-precipitation process to provide good interfacial adhesion and homogenous dispersion within the polyamide-12 matrix. The particle size and micro-morphology analyses show that the CF/PA composite powders with 30 wt%, 40 wt% and 50 wt% carbon fibres present the suitable powder sizes and format for SLS. The incorporation of carbon fibres into the polyamide-12 matrix decreases the initial melting temperature and consequently lowers the SLS part bed temperatures, implying lower energy requirement and less thermal degradation in the sintering process. The CF/PA composites also represent higher thermal stability than the pure polyamide-12. The CF/PA sintered components with 30 wt%, 40 wt% and 50 wt% carbon fibres exhibit the greatly enhanced flexural strengths by 44.5%, 83.3%, 114%, and the flexural modulus by 93.4%, 129.4%, 243.4%, respectively, as compared with the pure polyamide-12 sintered parts. Fractured surface analysis shows that the carbon fibres are encapsulated and bonded well with the polyamide matrix. The complex SLS parts with the thinnest wall of 0.6 mm, the density of 1.09 ± 0.02 g/cm³ and the relatively density of 94.13 ± 1.72% were manufactured using the CF/PA composite powder with 30 wt% carbon fibres. This study demonstrates that the CF/PA composite powders prepared by the surface treatment and dissolution-precipitation method represent suitable interfacial adhesion, filler dispersion, particle sizes and sintering behaviours for SLS and enable the manufacture of complex components with high performance.