Solenoid pumps for flow injection analysis

Methods employing flow injection analysis (FIA), particularly for in situ seawater techniques, would benefit from reduction in pump size and power requirement, longer maintenance intervals, and the ability to incorporate microprocessor control of each reagent and sample flow stream. In this work, the peristaltic pump of a conventional FIA system was replaced by three solenoid-driven diaphragm pumps with integral Viton check valves, and the system was tested by performing the simple nitrite analysis, which has well-defined FIA performance characteristics. Sixty injections per hour were possible with flow rates of 0.5 mL/min for reagents and sample. The coefficient of variation was 1% for 10 μM NO(2)(-) concentrations, and the detection limit was less than 0.1 μM NO(2)(-). These values match the reported performance for this method using peristaltic pumps.     

Preparation,characterization and application of Fe3O4/ZnO core/shell magnetic nanoparticles

Fe₃O₄ magnetic nanoparticles (MNPs) were synthesized by a co-precipitation method. The phase purity was confirmed by X-ray powder diffraction (XRD) analysis. The crystal size was found to be 10 nm from transmission electron microscopy (TEM). It is evidenced that the surface of Fe₃O₄ MNPs was modified by sodium citrate. The Fe₃O₄/ZnO core/shell MNPs were obtained by coating the MNPs with direct precipitation using zinc acetate and ammonium carbonate. The precursor was firstly dried and then calcined at 350 °C. The antioxidation tests indicated that the core/shell MNPs give better antioxidation than that of the Fe₃O₄ MNPs. The photocatalytic degradation of methyl orange revealed that the core/shell MNPs have higher photocatalytic activity than that of the ZnO nanoparticles. Separation of the core/shell MNPs from the aqueous suspension using a magnet provides an easy way to recycle the core/shell MNPs. After four-time recycling, the photocatalytic degradation percentage of the core/shell MNPs is about 70%.     

锶磁性光催化剂的制备和表征

以自制碳酸锶(SrCO3)和钛酸丁酯为原料,采用超声波技术制备了以锶铁氧体(SrFe12O19)为载体的锶磁性光催化剂(TiO2-SrFe12O19)。采用XRD、IR、VSM、N2吸附实验等手段研究了催化剂的表面性质和磁学特性。结果表明,该催化剂的平均晶粒尺寸在20～30nm之间,比表面积为44.8m2/g,平均孔径为7.09nm,属于介孔磁性材料;饱和磁化强度(Ms)为12.9A.m2/kg,矫顽力(Hc)为120.9kA/m,易于磁分离和重复利用。催化剂对亚甲基蓝(MB)的催化降解脱除率为94.7%,且重复使用3次,催化降解效率不低于88%,表明催化性能稳定,重复使用效果良好。     

煤油基Fe3O4磁性流体制备及表征

以FeCl3和FeSO4为铁源,以煤油为载液,用油酸为表面改性剂,采用一步法制备煤油基FeSO4磁性流体.研究发现油酸可以成功地包覆在磁性颗粒表面,FeSO4磁性颗粒平均粒径为10～20nm,晶型为反尖晶石型;磁性流体磁化率为6.53X10-4,磁化强度为20.9emu/g,可以长期稳定存在.     

磁性聚乙烯醇缩丁醛微球的制备和性质

运用乳化复合技术制备出磁性聚乙烯醇缩丁醛微球。该微球呈珠状 ,平均粒径为10～ 2 0nm ,具有较大的蛋白质固载量 ,可作为载体对多种酶及蛋白质加以固定。并研究了磁性聚乙烯醇缩丁醛微球制备条件、吸附时间、pH值等对磁性聚乙烯醇缩丁醛微球固定蛋白载量的影响     

微反应器中LaPO4:Eu3+纳米棒的制备及表征

以Eu2O3、La(NO3)3·6H2O和NaHzPO4·2H2O为原料、乙二醇为溶剂,在微反应器中合成了铕掺杂磷酸镧(LaPO4:Eu3 )纳米棒.采用X射线衍射仪(XRD)、透射电子显微镜(TEM)和荧光光谱仪对LaPO4:Eu3 纳米棒的物相、微结构和荧光性能进行了表征.结果表明:LaP04:Eu3 纳米棒具有六方晶系的晶体结构,形貌为长度100nm左右,直径10nm左右的针状纳米棒,并且具有较强的荧光性能.     

超级电容器用石墨烯的制备与性能研究

在高浓度硫酸铵溶液中还原制备了石墨烯,对石墨烯的结构与形貌以及电化学性能进行表征。以硫酸铵作为液相中还原石墨烯的添加剂,在还原时能够有效防止还原石墨烯结块,保持良好的片状结构。还原石墨烯的比表面积达到了615m2/g,内部孔径分布在2.2nm到20nm的范围内,主要集中在2.5nm左右。片状多孔石墨烯最大比电容达到了191F/g,2000次充放电测试之后,比电容依然能保持在首次循环的95%以上。     

Preparation and characterization of curcumin thermosensitive hydrogels for intratumoral injection treatment

Objectives: This paper describes the development and optimization of curcumin thermosensitive hydrogels (CTH), a kind of gel injection for intratumoral injection treatment.

Methods: Aimed at increasing the content and stability of effective components, an optimal formulation of CTH was chosen based on the results from orthogonal tests and the optimal pH was determined by stability test. To investigate the hydrogels drug release in vitro, residence time by RP-HPLC and therapeutic effects on ascitic hepatocarcinoma cell strain with high metastasis potential in lymphatic system (HCA-F) solid tumors in mice.

Key findings: The selected optimal formulation of CTH was: 0.2% curcumin, 20% poloxamer 407, 4% poloxamer 188, 8% polyethylene glycol 400, 12% 1,2-propanediol and pH was 6.0. The drug release determined by RP-HPLC fit to the Higuchi model. The residence time of CTH was longer than the curcumin suspensions. Intratumoral injection of the CTH can effectively inhibit the growth of HCA-F solid tumors in mice.

Conclusions: The CTH prepared in this test demonstrates proper gel temperature and viscosity. It improves the solubility of curcumin with a relatively long period of drug release in vitro and residence time. Intratumoral injection of the CTH can effectively inhibit the growth of HCA-F solid tumors in mice.     

Preparation, characterization, and electrochemical application of mesoporous copper oxide

Mesoporous CuO was successfully synthesized via thermal decomposition of CuC₂O₄ precursors. These products had ring-like morphology, which was made up of nanoparticles with the average diameter of 40 nm. The electrochemical experiments showed that the mesoporous CuO decreased the overvoltage of the electrode and increased electron transference in the measurement of dopamine.     

Optimization and characterization of a flow injection electrochemical system for pentachlorophenol assay

A flow injection (FI) electrochemical detection system has been developed and optimized for the determination of pentachlorophenol (PCP) in contaminated soil. PCP was oxidized to tetrachloro-1,4-benzoquinone (1,4-TCBQ) with a high yield using bis(trifluoroacetoxy)iodobenzene in 0.1 M tartaric acid, pH 2.0, at ambient temperature. Upon rapid reaction with immobilized glucose oxidase, the detection and amplification scheme was completed as the reduced form of 1,4-TCBQ or tetrachloro-1,4-hydroquinone was reoxidized to 1,4-TCBQ at the surface of the glassy carbon electrode (+ 0.40 V vs Ag/AgCl). Rapid electron exchange between the enzyme and its glucose substrate provided a non-rate-limiting current toward the electrode. The FI electrochemical system was linear up to 1 μM oxidized PCP with a detection limit of 10 nM and exhibited a reproducibility of ±0.6% over 165 repeated analyses during 14 h of continuous operation. When applied to PCP-contaminated soil samples, the results obtained from the FI electrochemical system compared well with those of the HPLC standard method.     

磁性羟基磷灰石复合物的制备与表征

为探索磁性颗粒在治疗因缺乏骨骼应有的应力刺激而导致骨质疏松方面的潜在应用,研究制备了兼具良好生物活性和超顺磁性的羟基磷灰石(HA)/Fe3O4复合物。以化学沉积法合成的纳米Fe3O4浆料为底物,在Ca、P溶液中通过尿素酶催化水解尿素缓慢升高pH值,从而使HA逐渐在Fe3O4上沉积,形成具有一定核壳结构的磁性HA复合物。利用X射线衍射(XRD)、扫描电镜(SEM)、透射电镜(TEM)、X射线能量色散谱仪(EDX)、振动样品磁强计(VSM)和磁铁对底物及试样进行了表征。结果表明,以纳米Fe3O4浆料为底物,一定浓度含氯化钠的Ca、P溶液(Ca、P原子比为5∶3,Ca、Fe原子比为5∶3)为媒介,在37℃水浴中,反应48h,可制得具有较好磁性能的HA复合物,其饱和磁化强度可达7.23A.m2/kg,剩磁为0.073A.m2/kg,矫顽力为261.08A/m。     

Mid-infrared quantum cascade lasers for flow injection analysis

A Fabry-Perot quantum cascade laser (QCL) was used as a powerful light source for mid infrared (MIR) detection in flow injection analysis. The QCL lased at several wavelengths close to each other within a few wavenumbers (990-1010 cm-1), hence fitting well to the broad absorption bands of molecules in liquid phase. As compared with that of a state-of-the-art Fourier transform spectrometer, the signal-to-noise ratio could be improved by a factor of 50. Additionally, by using a QCL as the light source, optical path lengths of more than 100 microns could be used even in aqueous matrixes which reduced the danger of cell clogging. In the example shown here phosphate was determined in Diet Coke samples. The flow injection system used allowed the measurement of the sample at two pH values (5 and 13) at which the analyte was present as H2PO4- and PO4(3-), respectively. As the analytical readout the difference in IR absorption of H2PO4- and PO4(3-) at the laser wavelengths was taken. The FIA-QCL measurements were corroborated by ion chromatography which was used as a reference method.     

Preparation and characterization of spray-dried submicron particles for pharmaceutical application

The versatile use of submicron-sized particles (0.1–1?μm) requires new manufacturing methods. One possibility for the preparation of submicron-sized particles is spray drying. However, the generation of small droplets at a high production rate and the precipitation of submicron particles are quite challenging. In order to produce a sufficient amount of fine and uniform droplets, a two-fluid nozzle with internal mixing was combined with a cyclone droplet separator. The precipitation of particles was realized with an electrostatic precipitator. Considering the difficulty of electrostatic precipitation concerning explosion risks and to make it capable using organic solvents, the spray dryer was integrated in a pressure resistant vessel. Based on previous experiments, the now presented design is compact and the electrostatic precipitator is shortened. In addition, enhanced drying conditions ensured a controlled and reproducible preparation of submicron-sized particles. Thus, high separation efficiencies were shown. Spray-drying experiments were conducted with the model substance mannitol. With the cyclone droplet separator, a fine and uniform spray with a droplet size smaller 2?μm was produced. This robust atomizing technique is capable for high concentrations. For a 10?wt% mannitol solution, particles in the submicron range d_50,3?=?0.7?μm were produced.     

Preparation and characterization of vanadium-doped ZnO nanoparticles for environmental application

Vanadium-doped ZnO nanoparticles (ZnO:V) were prepared via flame spray pyrolysis (FSP) from a mixed aqueous solution of zinc hydroxide and vanadyl (IV) acetylacetonate. The morphological, structural and optical properties of the ZnO:V photocatalyst were characterized via transmission electron microscopy (TEM), X-ray powder diffraction (XRD), and UV-visible diffused reflection spectrum (DRS). The photocatalytic activity of ZnO:V was evaluated via photocatalytic degradation of methylene blue (MB). The results showed that the hexagonal wurtzite-structured ZnO:V nanoparticles were successfully synthesized via FSP. The morphology of the as-prepared nanoparticles was polyhedral and non-hollow. The average diameter of ZnO:V, which was calculated from BET result, was 11.7 nm when the molar ratio of V/Zn was 0.1. The maximum decomposition of MB by the ZnO:V nanoparticles was 99.4% after 180 min under UV irradiation, whereas the decomposition of MB by the pure ZnO nanoparticles was 96.6%.     

磁性高分子微球的制备及生物医学应用

综述了磁性高分子微球的组成、分类及制备方法 ,介绍了其在生物医学方面的应用 ,并展望了今后的研究方向。     

磁性陶瓷靶材的制备及其应用研究

薄膜制备过程中溅射靶材的利用率很低,导致薄膜材料制备成本很高。以自制的高纯度纳米晶镍钴锌/二氧化硅复合铁氧体粉体为原料,冷等静压后高温烧结制备得到铁氧体复合靶材。用XRD、EPMA和SEM分析靶材的化学成分和微观形貌。结果表明：靶材为尖晶石型铁氧体和二氧化硅的复合材料,收缩率达14.37%,能在高真空多功能磁控溅射仪正常工作,并成功制备得到性能良好的软磁薄膜。整个制备过程工艺简单,操作方便可行,大大降低了靶材的制备成本。     

聚苯胺/磁性纳米复合材料的制备及应用

聚苯胺/磁性纳米复合材料具有电磁性,有广泛的应用前景,已成为纳米材料研究的热点之一.主要介绍了聚苯胺/磁性纳米复合材料的制备方法与材料性质及其应用,分析了原位聚合、溶胶-凝胶法、自组装技术等制备方法的优缺点,并指出了聚苯胺/磁性纳米复合材料的研究方向.     

Preparation and characterization of temperature-responsive magnetic composite particles for multi-modal cancer therapy

The temperature-responsive magnetic composite particles were synthesized by emulsion-free polymerization of N-isopropylacrylamide (NIPAAm) and acrylamide (Am) in the presence of oleic acid-modified Fe₃O₄ nanoparticles. The magnetic properties and heat generation ability of the composite particles were characterized. Furthermore, temperature and alternating magnetic field (AMF) triggered drug release behaviors of vitamin B₁₂-loaded composite particles were also examined. It was found that composite particles enabled drug release to be controlled through temperature changes in the neighborhood of lower critical solution temperature. Continuous application of AMF resulted in an accelerated release of the loaded drug. On the other hand, intermittent AMF application to the composite particles resulted in an “on–off”, stepwise release pattern. Longer release duration and larger overall release could be achieved by intermittent application of AMF as compared to continuous magnetic field. Such composite particles may be used for magnetic drug targeting followed by simultaneous hyperthermia and drug release.     

Preparation and characterization of antifouling thermosensitive magnetic nanoparticles for applications in biomedicine

Copolymer brushes grafting onto magnetic nanoparticles (MNPs) were prepared via surface free radical polymerization to improve antifouling properties of thermosensitive MNPs. A chain transfer agent was firstly attached to MNPs by silanization. Copolymerization of poly(ethylene glycol) monomethacrylate and N-isopropylacrylamide was then conducted to graft polymer brushes on the particles surface via surface free radical polymerization. The lower critical solution temperature of the obtained thermosensitive MNPs is 43 °C, which is higher than that of homopolymer poly(N-isopropylacrylamide). Nonspecific adsorption of protein was resisted at room temperature and 45 °C. The result suggested that poly(ethylene glycol) monomethacrylate segments decrease nonspecific adsorption of protein above LCST.