核-壳型罗丹明6G磁性分子印迹固相萃取材料的合成与表征

采用化学共沉淀法制备Fe3O4磁性纳米粒子,以3-氨丙基三乙氧基硅烷(APTES)对其表面进行氨基硅烷化改性,形成Fe3O4@SiO2-NH2纳米粒子。以其作为磁性核,采用表面印迹技术,以罗丹明6G为模板,丙烯酰胺(AM)为功能单体,三羟甲基丙烷三甲基丙烯酸酯(TRIM)为交联剂,在Fe3O4@SiO2-NH2表面形成罗丹明6G分子印迹聚合膜,制备了核-壳型罗丹明6G磁性分子印迹聚合物(Fe3O4@MIPs),对合成条件进行了优化。分别采用红外光谱(FT-IR)、场发射扫描电镜(FESEM)、振动样品磁强分析(VSM)和热重分析(TGA)等仪器分析手段,对Fe3O4@MIPs的结构进行表征。结果表明,所制备的核-壳型磁性分子印迹聚合物具有高吸附容量及显著选择性;在外加磁场作用下Fe3O4@MIPs可快速与样品基质分离,大大提高了实验效率。Fe3O4@MIPs作为一种新型固相萃取材料,可以从样品中选择性分离和富集违规添加的罗丹明6G,可应用于食品的安全检测。     

Synthesis and characterization of Ag/polyaniline core-shell nanocomposites based on silver nanoparticles colloid

Ag/polyaniline core-shell nanocomposites were successfully synthesized via in situ chemical oxidation polymerization of aniline based on mercaptocarboxylic acid capped Ag nanoparticles colloid. The morphology and structure of the products were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy and UV-Vis spectra. A possible formation mechanism of the Ag/polyaniline core-shell nanocomposites was also proposed.     

Hydrothermal tuning of morphology of aluminophosphate (AlPO-14) framework for the adsorption of Rhodamine 6G dye

A crystalline zeolite material AlPO-14 was synthesized using Taiwanese coal fly ash (CFA) for the separation of cationic dyestuff Rhodamine 6G (R 6G) from aqueous stream. The zeolite synthesis was performed at different fusion ratios (CFA:NaOH) of 1:1, 1:1.5, and 1:2 followed by hydrothermal treatment resulted AlPO-14 zeolite frameworks (Z1, Z2, and Z3). The physico-chemical, structural, functional, morphological aspects of the raw CFA, and the zeolites were characterized via XRF, XRD, FT-IR, SEM, and BET methods. Further, the zeolites were tested their applicability adsorbing the cationic R 6G dye in batch mode. Moreover, the influence of pH, adsorbent dosage, initial dye concentration, temperature, agitation speed, kinetic models, adsorption isotherms on the removal of R 6G onto zeolites were emphasized. The results indicate that, neutral pH favors the separation of R 6G (q_m = 208.11 mg/g) following Langmuir isotherm model, and best fitted to pseudo-second order kinetic model. Lastly, the adsorbent was responsive to the alkaline medium (NaOH), and can be readily retrieved for reuse, i.e., Z2 can be reused for 5 successive cycles, followed by Z1-3 times and Z3-2 times respectively. In summary, the major note downs were CFA based AlPO-14 had a commercial potentiality in adsorption applications and regarded to be a new entrant into zeolite database.     

Tuning luminescence intensity of RHO6G dye using silver nanoparticles

The photoluminescence (PL) from rhodamine (RHO6G) dye dispersed in ethanol has been studied in the presence of different amounts of citrate stabilized silver nanoparticles of size, ∼10 nm. Enhancement as well as quenching of luminescence intensity has been observed and it was found that luminescence intensity can be tuned by adding various amounts of silver nanoparticles to the RHO6G dye dispersion. The luminescence spectra of dye consist of two peaks at 440 nm and 550 nm. Peak at 440 nm shows an enhancement in intensity at all the concentrations of added silver nanoparticles with the maximum intensity for dye with 0.25 ml silver nanoparticles (82% enhancement in the luminescence intensity). PL intensity of intense peak at 550 nm of dye molecules was found to be quenched in presence of silver nanoparticles and maximum quenching was found to be 41% for the dye with 1 ml silver nanoparticles. However, for lowest concentration of silver nanoparticles viz. (0.01 ml), enhancement in intensity was observed (13% enhancement than the dye molecules). The quenching as well as enhancement in the intensity can be understood by considering the possibility of three different phenomena. It has been reported earlier that when metal nanoparticles are in close proximity to the fluorophores, quenching of luminescence occurs, whereas when metal nanoparticles are located at certain distance, enhancement in luminescence is observed. This effect has been explained by coupling of surface plasmon resonance from metal nanoparticles with fluorophore, resulting in the increase of excitation and emission rate of the fluorophore in the localized electromagnetic field. The quenching and enhancement of luminescence intensity of the dye molecules can also be explained as the transfer of electrons from dye to the silver nanoparticles and to an extent it can be attributed to the aggregation of dye molecules upon addition of silver nanoparticles.     

Low-field magnetoresistance effect in core-shell structured La(0.7) Sr(0.3) CoO(3) nanoparticles

Core-shell structured La(0.7) Sr(0.3) CoO(3) nanoparticles are synthesized and their magnetic and magneto-transport properties are investigated. In these core-shell La(0.7) Sr(0.3) CoO(3) nanoparticles, the cores are single-crystalline and ferromagnetic, whereas the shells are noncrystalline and predominantly paramagnetic. Moreover, the insulating-like shells can serve as a good spin tunneling barrier. Therefore, in such a special core-shell structure, the spin-polarized interparticle tunneling is improved due to the existence of shells, which thus induces an enhanced low-field magnetoresistance effect.     

Physical and chemical effects on the dynamics of the β-relaxation of PMMA in Rhodamine 6G+PMMA+SiO<Subscript>2</Subscript> matrices

The Thermally Stimulated Depolarization (TSD) Current technique has been used to reveal confinement effects on the β-relaxation process of PMMA polymerized in-situ SiO₂ in the presence of the laser dye Rhodamine 6G/Cl^– (Rh6G). The TSD current band of the β process, associated with the rotational relaxation of the mobile carboxymethyl side groups of PMMA, presents a drastic low temperature shift with the introduction of Rh6G or the confinement of PMMA in the nanometric silica substrate. By using the fractional polarization technique we have decomposed this band into single current signals. Irrespective of the initiator type used in the polymerization process, the broad activation energy distribution associated with the β process is nearly identical in the Rh6G+PMMA+SiO₂ materials and bulk PMMA. The increase of the dye concentration enlarges the band shift, without any significant modification in the TSD current spectrum (i.e. distinct bands from the polar chromophore). The changes in the molecular dynamics of the polar carboxymethyl side groups of PMMA are discussed in terms of the hydrogen-bond interactions between the silicic acid pore surface and the basic side-groups of PMMA and the decrease of the polymer chain entanglements due to pore directed propagation of polymerization. The relative importance of the various types of interactions between the two chemically identifiable phases in the presence of the dye is discussed. Electronic Publication     

SiO2 / Ni 核壳结构纳米粒子的制备及其磁性能

以硅酸钠为主要原料, 通过液相沉淀法在纳米镍粉表面包覆了一层SiO₂ 。应用XRD、FTIR、TEM、TGA、DSC 和VSM 对复合粉体的结构、形貌和磁性能进行了研究。结果表明, SiO₂ 以非晶态的形式包覆在纳米镍粒子表面, 形成了核壳结构, 降低了纳米粉体的团聚现象。TGA 和DSC 结果表明, SiO₂ 的包覆提高了纳米粉体的抗氧化性。磁性分析结果表明, 粉体包覆前由于表面氧化层(NiO) 的存在, 粉体的磁滞回线偏移; 包覆后的粉体由于SiO₂的存在, 饱和磁化强度降低, 矫顽力升高。      

Preparation and electromagnetic wave absorption properties of hollow Co,Fe@air@Co and Fe@Co nanoparticles

In this study, hollow Co, Fe@air@Co and Fe@Co nanoparticles (NPs) have been synthesized respectively by electroless plating Co shell on Fe core and controlling reaction time based on galvanic cell reaction between Co shell and Fe core in hydrochloric acid at room temperature. The electromagnetic (EM) wave absorption properties of these three NPs are also been investigated. The results indicate that the relationship between Fe core and Co shell is critical to the EM wave absorption properties of hollow Co, Fe@air@Co and Fe@Co nanoparticles when blended with 70?wt% in paraffin-based samples. Fe@air@Co nanoparticles shows the best EM wave absorption properties with minimum reflection loss of ?42.75?dB and effective bandwidth of 4.1?GHz under ?10?dB. The present work has a significant potential for the development of EM wave absorbing materials with core-shell structure.     

Enhancement of the photoelectrochemical response of poly(terthiophenes) by CdS(ZnS) core-shell nanoparticles

We have investigated the photoelectrochemical properties of hybrid films of polythiophenes poly(4,4″dimethoxy-3′-methyl-2,2′:5′,2″ terthiophene) (PDM), poly(4,4″dipentoxy-3′-methyl-2,2′:5′,2″ terthiophene) (PDP), and cadmium sulfide/zinc sulfide (CdS(ZnS)) core-shell nanoparticles. Although CdS(ZnS) nanoparticles present enhanced exciton trapping, light harvesting by hybrid films was enhanced when compared to those of pure PDM and PDP films. This enhancement is explained in terms of electron and hole transfer mechanisms at different excitation wavelengths. The more efficient light harvesting of PDM/CdS(ZnS) when compared to that of PDP/CdS(ZnS) was attributed to its broader absorption spectrum and more efficient electron hopping.     

Enhanced luminescence of UV irradiated Zn(1−x)NixS nanoparticles

PVP-capped Zn_(1−x)Ni_xS (x = 0.001, 0.005, 0.01, 0.03, 0.05 and 0.1) nanoparticles have been synthesized using chemical precipitation route, in aqueous media, at room temperature. The synthesized nanoparticles have been irradiated by UV light for 24 h so as to study the effect on their structural and optical properties. The nanoparticles have been characterized through XRD and HRTEM to study the crystal structure and size. Characterization was also carried out through FTIR spectroscopy to reveal the presence of PVP and the effect of UV irradiation on the surface chemistry of the synthesized nanoparticles. The optical properties have been studied through UV–vis absorption spectroscopy and room temperature photoluminescence. There has been an enhancement in the intensity of the green emission centered at 547 nm, with increase in Ni concentration up to 0.5 at.% and a decrease in the intensity, observed for higher concentrations of Ni. However, the I(green)/I(blue) intensity ratio increases continuously with the increase in Ni concentration and also on prolonged UV irradiation of the samples.     

Structural,mechanical, and electrical properties of carbon nanoparticles synthesized from diesel

We studied the elemental analysis, structural morphology, mechanical, and electrical properties of carbon nanoparticles synthesized from diesel. The spherical carbon particle size in the range of about 10 to 80 nm in diameter was observed in scanning electron microscope (SEM) studies that were identified by Atomic force microscopy (AFM) study as an aggregation of carbon particles of average size 2.5 nm. The surface rms of carbon nanoparticle thin film (CNTF) was measured directly by AFM and found 0.22 nm. The Derjaguin–Muller–Toporov (DMT) elastic modulus of carbon nanoparticles (CNPs) was measured by PeakForce QNM mode of AFM. The minimum and maximum elastic modulus was measured of 0.40 GPa and 43.89 GPa, respectively. The resistivity, conductivity, magneto resistance, mobility, and average Hall co-efficient were measured by “Ecopia Hall-effect measurement system” by four-point Van der Pauw approach at ambient condition. We demonstrated I–V characteristic at the Indium/CNTF thin film interface, which is accompanied by rectifying behavior.     

Facile combustion synthesis and photoluminescence properties of Ce3+ doped Sr2La8(SiO4)6O2 phosphors

The Sr₂La₈(SiO₄)₆O₂:Ce³⁺ powder phosphor with apatite structure has been successfully synthesized via a facile route of sol-combustion technique. X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), and photoluminescence (PL) spectroscopy were used to characterize the as-prepared samples. Sr₂La₈(SiO₄)₆O₂:Ce³⁺ phosphor was composed of particles with average sizes range about 300 nm. The phosphor exhibited an absorption ranging from 220 to 390 nm in ultraviolet range and a broad blue-violet emission band peaked at 403 nm with a CIE coordinates of (0.167, 0.028). The concentration quenching mechanism was also determined to be dipole–dipole interaction.     

有机蒙脱土对ABS-PA6共混物形态结构与力学性能的影响

熔融挤出制备了不同有机蒙脱土(OMMT) 含量的OMMT/丙烯腈-丁二烯-苯乙烯(ABS) -尼龙6 (PA6) (30/70,质量比) 复合材料,用透射电子显微镜(TEM),扫描电子显微镜(SEM) 等研究了OMMT在ABS-PA6共混物中的分布及其对ABS-PA6共混物形态结构与力学性能的影响。结果表明:在OMMT/ABS-PA6复合材料中,OMMT主要以剥离形态分布在PA6基体相中,少量分布在PA6与ABS两相界面处,具有明显的选择分布性;随着 OMMT含量增加,ABS分散相尺寸逐渐减小且分布均匀OMMT/ABS-PA6 复合材料的强度、模量逐渐提高,当OMMT含量为7 wt%时 , 弯曲强度和模量分别由未加OMMT时的66. 7 MPa、2. 308 GPa上升至94. 1 MPa、3. 184 GPa,缺口冲击强度在OMMT含量为3 wt%时出现极大值3. 7 kJ / m,但总体变化不大。      

Enhancing the grafting of poly(2-hydroxyethyl methacrylate) on silica nanoparticles (SiO2-g-PHEMA) by the sequential UV-induced graft polymerization with a multiple-UV irradiation

Grafting of poly(2-hydroxyethyl methacrylate) on silica nanoparticles was accomplished via the sequential UV-induced graft polymerization. Under UV-irradiation, the silica was functionalized with the surface initiator, benzophenone (BP) and subsequently graft-polymerized with 2-hydroxyethyl methacrylate (HEMA). The grafting on the silica particles was confirmed by DSC analysis which revealed a shift of the glass transition temperature (T_g) of grafted PHEMA to higher temperature than T_g of ungrafted PHEMA. A significant improvement in the grafting efficiency and the grafting percentage was achieved when a sequential grafting approach was taken, employing multiple UV exposures. Using this approach, the efficient chain extension from the grafted-PHEMA was possible without producing significant amounts of ungrafted PHEMA when low HEMA concentrations were used during each UV-exposure.     

Adsorption and desorption of CO on Ni decorated stepped Rh(553)

Vicinal surfaces are important in surface science, as they show interesting electronic structures and reactivities due to the steps. In this paper the adsorption and desorption of carbon monoxide on the stepped Rh(553) surface decorated with Ni is reported. With 0.1 to 0.3 monolayer Ni on Rh(553) one and two atoms broad Ni wires along the Rh steps are formed. The adsorption and desorption of carbon monoxide on these surfaces is investigated using thermal desorption spectroscopy (TDS) and reflection absorption infra red spectroscopy (RAIRS). TDS shows a marked change from just one broad TDS peak on pure Rh(553) to 4 distinct peaks with increasing Ni decoration. RAIRS shows that already at 0.1 monolayer Ni the CO adsorption states on bridge sites on the Rh step atoms are completely quenched. In addition it is shown that with Ni films up to 3 monolayer the on top adsorption sites for CO on Ni are preferred over the bridge and hollow adsorption sites in contrast to what is known from the Ni(111) surface.     

中国不同纬度野生大豆和栽培大豆AFLP分析

采用ＡＦＬＰ分子标记技术,对我国不同纬度的２０份野生大豆和载培大豆（Ｇ．ｍａｘ）进行了多样性分析,结果表明：（１）我国野生大豆的遗传多样性较栽培大豆更为丰富;（２）根据ＡＦＬＰ分析结果,将野生大豆和栽培大豆完全划分为２类,并发现野生大豆栽培大豆的种特异谱带,说明野生大豆和栽培大豆作为２个种有遗传基因的;（３）野生大啼和栽培大豆不同纬度品种间纬度相傧首先聚在一起,表明不同进化类型的大豆其遗传距离与纬     

Structural,electrical, and rheological properties of palladium/silver bimetallic nanoparticles prepared by conventional and ultrasonic-assisted reduction methods

Polyvinylpyrrolidone stabilized Pd/Ag bimetallic nanoparticles (NPs) with average particle sizes of 9 and 6 nm were synthesized by simultaneous reduction in the presence and absence of ultrasound waves, respectively. The prepared NPs were characterized by six methods including X-ray diffraction (XRD), transmission electron microscopy (TEM), high resolution-TEM (HRTEM), UV–vis spectroscopy, scanning tunneling microscopy (STM), and energy dispersive X-ray (EDX) analysis. The rheological properties of Pd/Ag NPs in ethylene glycol as a base fluid with various mass fractions of NPs from 2% to 5% at different temperatures were studied experimentally and theoretically. The experimental results showed that viscosity of Pd/Ag NPs in ethylene glycol increases with increasing particle mass fraction and decreases with increasing temperature. A maximum of 31.58% increase in viscosity of ethylene glycol at 20 °C was observed when 5% Pd/Ag NPs was added. Measurement of the electrical conductivity of nanofluids of Pd/Ag bimetallic NPs in distilled water at different mass fractions and temperatures was performed. A 3841% increase in electrical conductivity of distilled water at 25 °C was observed when 1% Pd/Ag NPs was added. Both the rheological and electrical properties of Pd/Ag bimetallic NPs were measured in ethylene glycol and distilled water, respectively for the first time.     

Thermal evolution and optical properties of Cu nanoparticles in SiO2 by ion implantation

SiO₂ samples were implanted by 45 keV Cu ions at a dose of 1 × 10¹⁷ /cm², and subjected to furnace annealing at temperatures ranging from 200 to 600 °C in nitrogen atmosphere. The results indicate that the Cu nanoparticles have been synthesized by Cu ion implantation, and subsequent annealing induces the diffusion and nucleation of nanoparticles partially. The results from XPS measurements show that the Cu⁰ is the dominate charge state in the implanted and subsequent annealed samples. With increasing annealing temperature, the size and distribution of Cu nanoparticles have been modified gradually. The surface plasmon resonance (SPR) of Cu nanoparticles at 570 nm has been observed by optical transmission spectroscopy. The strongest SPR signal at 400-600 °C indicates that lots of Cu nanoparticles have grown and show good optical properties. Moreover, the luminescence has been investigated in Cu implanted and subsequent annealed samples. Possible luminescence mechanisms, such as radiation induced defects, Cu (ions or atoms) related luminescence centers, etc., have been discussed.     

PA66短纤维用于提高聚甲基乙撑碳酸酯力学与热学性能的研究

聚甲基乙撑碳酸酯(PPC)分子间作用力较低、力学和热学性能较差,通过双螺杆挤出制备PPC/PA66短纤维复合材料,促进PA66短纤维与PPC形成氢键作用力,有利于提高PPC材料的综合性能。红外光谱分析结果表明PA66短纤维的羰基与PPC分子链中的羟基之间形成了氢键,PA66短纤维的引入提高了PPC的力学性能和热学性能。当短纤维含量为20%(质量分数)时,复合材料的缺口冲击强度提高了315.8%,初始分解温度和玻璃化温度分别提高了32.2和3.8℃。当短纤维含量继续增加至30%(质量分数)时,由于高含量的纤维之间容易发生团聚,导致复合材料的力学性能略有下降。PPC力学和热学性能的显著提高,主要原因是氢键作用力的形成和PA66短纤维受力后发生的拉丝形变所引起。