Systematic evaluation of biocompatibility of magnetic Fe<Subscript>3</Subscript>O<Subscript>4</Subscript> nanoparticles with six different mammalian cell lines

This article systematically evaluated the biocompatibility of multiple mammalian cell lines to 11-nm DMSA-coated Fe₃O₄ magnetic nanoparticles (MNPs). Cells including RAW264.7, THP-1, Hepa1-6, HepG2, HL-7702, and HeLa were incubated with six different concentrations (0, 20, 30, 40, 50, and 100 μg/mL) of MNPs for 48 h, and then the cell labeling, iron loading, cell viability, apoptosis, cycle, and oxidative stress were all quantitatively evaluated. The results revealed that all the cells were effectively labeled by the nanoparticles; however, the iron loading of RAW264.7 was significantly higher than that of other cells at any dose. The proliferations of all the cells were not significantly suppressed by MNPs at the studied dose except HepG2 that was exposed to 100 μg/mL MNPs. The investigation of oxidative stress demonstrated that the levels of total superoxide dismutase and xanthine oxidase had no significant changes in all the cells treated by all the doses of MNPs, while the levels of malonyldialdehyde activity of MNP-treated cells significantly increased. The nanoparticles did not produce any significant effect on cell cycles at any of the doses, but resulted in significant apoptosis of THP-1 and HepG2 cells at the highest concentration of 100 μg/mL. At a concentration of 30 μg/mL which was used in human studies with an intravascular nanoparticle imaging agent (Combidex), the nanoparticles efficiently labeled all the cells studied, but did not produce any significant influence on their viability, oxidative stress, and apoptosis and cycle. Therefore, the nanoparticles were concluded with better biocompatibility, which provided some useful information for its clinical applications.     

On the formation of nanocomposite TiC/a-C:H coatings by the method of the magnetron sputtering of Ti in an electron-beam activated Ar/C2H2 mixture

Composite TiC/a-C:H coatings with a thickness of 5 μm are produced by the reactive magnetron sputtering of titanium in an Ar/C₂H₂ gas mixture, which was additionally irradiated by a wide electron beam with an energy of 100 eV and an electric current of up to 1 A. The composition of the coatings is controlled by changing the C₂H₂ flow rate in the range from 1 to 16 mL/min under a constant Ar flow rate (40 mL/min) and magnetron current (2 A, 10 μs, 50 kHz). X-ray diffraction (XRD) investigations and high resolution transmission electron microscopy (HRTEM) methods confirm the formation of nanostructured coatings with a thickness of 4 to 9 nm. The hardness of the coatings nonmonotonically depends on the acetylene-flow rate. A maximum microhardness of 30 GPa is obtained when the atomic concentration of titanium in the coating determined by the Auger spectroscopy method is close to 38%. It is established that the electron-beam irradiation of a gas mixture during the deposition of coatings promotes the accelerated decomposition of acetylene and leads to a multiple (from 10 to 2 mL/min) decrease in the C₂H₂ flow rate, at which the maximum microhardness of coatings is reached.     

Ionic liquids-doped organic-inorganic hybrid film for electrochemical immunoassay for hepatitis B surface antigen

A new mediator-free amperometric immunoassay for hepatitis B surface antigen (HBsAg) in human serum was designed by means of immobilizing horseradish peroxidase-hepatitis B surface antibodies conjugates (HRP-HBsAb) on ionic liquids-doped organic-inorganic hybrid film. The composite film including magnetic nanogold particles and nanoalumina particles provides a friendly microenvironment for the immobilization of biomolecules. The presence of ionic liquids enhances the electron communication between the immobilized biomolecules and the base electrode and improves the sensitivity of the electrochemical immunoassay. With a non-competitive immunoassay format, the formation of the immunocomplex between the immobilized HRP-HBsAb and HBsAg in sample solution exhibited a barrier of direct electrical communication between the immobilized HRP and the base electrode and changed the bioelectrocatalytic properties of the immobilized HRP towards H₂O₂ in the detection solution. Under optimal conditions, the developed immunosensors displayed a good current response in a dynamic range from 1.2 to 430 ng/mL with a limit of detection of 0.3 ng/mL HBsAg (at 3s). The proposed immunosensors have good precision, high sensitivity, acceptable stability, and reproducibility and could be used for the HBsAg detection in human serum with consistent results in comparison with those obtained by the enzyme-linked immunosorbent assay method.     

Large GMI effect in Co-rich amorphous wire by tensile stress

Quality Co₆₈Fe_4.5Si₁₅B_12.5 amorphous wires are fabricated and their giant magneto impedance (GMI) effect are investigated at frequencies ranging from 0.1 to 20 MHz with or without tensile stress applied. Experimental results indicate that the GMI effect of these wires can be effectively improved by applying a small axial tensile stress. There is a pronounced increase from 1.3% to 47.3% in impedance ratio at 0.6 MHz when a stress of 103 MPa is applied. The GMI response is further increased to 261% by doing so at 15 MHz. The field sensitivity of these wires is optimized and it increases from 0.55 to 2.73%/(A/m) at 0.6 MHz and it is proved that the most sensitive field response is obtained by applying a tensile stress of 84.5 MPa below 1 MHz. With reference to the stress evolution of sensitivity at varying frequencies, the maximum field sensitivity shifts to a lower stress with increasing frequency. Quantitatively, a stress as small as 18.4 MPa is enough to yield a field sensitivity as high as 6.7%/(A/m) at 15 MHz. This demonstrates the possibility of achieving small stress (<100 MPa) induced large enhancement of GMI effect and field sensitivity at frequencies of several tens of MHz that are of much technical interest in sensor applications.     

A ratiometric fluorescent aptamer homogeneous biosensor based on hairpin structure aptamer for AFB1 detection

On the basis of aptamer (Apt) with hairpin structure and fluorescence resonance energy transfer (FRET), a ratio fluorescent aptamer homogeneous sensor was prepared for the determination of Aflatoxin B₁ (AFB1). Initially, the Apt labeled simultaneously with Cy5, BHQ2, and cDNA labeled with Cy3 were formed a double-stranded DNA through complementary base pairing. The fluorescence signal of Cy3 and Cy5 were restored and quenched respectively. Thus, the ratio change of F_Cy3 to F_Cy5 was used to realized the detection of AFB1 with wider detection range and lower limit of detection (LOD). The response of the optimized protocol for AFB1 detection was wider linear range from 0.05 ng/mL to 100 ng/mL and the LOD was 12.6 pg/mL. The sensor designed in this strategy has the advantages of simple preparation and fast signal response. It has been used for the detection of AFB1 in labeled corn and wine, and has good potential for application in real samples.

     

Double-beta-decay experiments: Present status and prospects for the future

The present status of experiments seeking double-beta decay is surveyed. The results of the most sensitive experiments are discussed. Particular attention is given to describing the NEMO-3 detector, which is intended for seeking the neutrinoless double-beta decay of various isotopes (¹⁰⁰Mo, ⁸²Se, etc.) with a sensitivity as high as T _1/2 ～ 10²⁵ yr, which corresponds to a sensitivity to the Majorana neutrino mass at a level of 0.1 to 0.3 eV. The first results obtained with the NEMO-3 detector are presented. A review of the existing projects of double-beta-decay experiments where it is planned to reach a sensitivity to the Majorana neutrino mass at a level of 0.01 to 0.1 eV is given.     

Enhanced-performance relative humidity sensor based on MOF-801 photonic crystals

We proposed an enhanced-performance relative humidity (%RH) nano-sensor based on MOF-801/TiO₂ one-dimensional photonic crystals (1DPC). The maximum reflectance-peak wavelength of it shifted obviously in the range of 20%-90% under varying %RH levels, due to the highly moisture-sensitive MOF-801 film in the 1DPC structure. It was demonstrated that the linear spectrum sensitivity of the MOF-801/TiO₂ %RH 1DPC sensor is exceeding 119 pm/%RH from 20%RH to 90% RH, and the sensitivity of reflection power variations exhibits 1.34 dB/%RH with the resolvable relative humidity variation less than 0.1%RH at 15°C. Meanwhile, the sensor shows a fast optical response time less than 100 ms with exceptional repeatability and reliability, which promises successful measurements of human respiration. Moreover, the sensor performance on the structure of 1DPC is investigated, representing a tradeoff between the sensing sensitivity and response time.     

Studies of high-pressure n-butane oxidation with CO2 dilution up to 100 atm using a supercritical-pressure jet-stirred reactor

A novel supercritical-pressure jet stirred reactor (SP-JSR) is developed to operate up to 200 atm. The SP-JSR provides a unique platform to conduct kinetic studies at low and intermediate temperatures at extreme pressures under uniform temperature distribution and a short flow residence time. n-Butane oxidations with varying levels of CO₂ dilutions at pressures of 10 and 100 atm and over a temperature range of 500-900 K were conducted using the SP-JSR. The experiment showed that at 100 atm, a weak NTC behavior is observed and the intermediate temperature oxidation is shifted to lower temperatures. Furthermore, the results showed that CO₂ addition at supercritical conditions slows down the fuel oxidation at intermediate temperature while has little effect on the low temperature oxidation. The Healy model under-predicts the NTC behavior and shows little sensitivity of the effect of CO₂ addition on the n-butane oxidation. Reaction pathway and sensitivity analyses exhibit that both the low and intermediate temperature chemistries are controlled by RO₂ consumption pathways. In addition, the reactions of CH₃CO (+ M) and CH₃CO + O₂ become important at 100 atm. The results also revealed that fuel oxidation kinetics is insensitive to the third body effect of CO₂. The kinetic effect of supercritical CO₂ addition may come from the reactions involving H₂O₂, CO, CH₂O, and CH₃CHO, especially for the reactions of CO₂ + H and CO₂ + OH.     

Graphene-based nitrogen dioxide gas sensors

In this study, we demonstrated that graphene could selectively absorb/desorb NO_x molecules at room temperature. Chemical doping with NO₂ molecules changed the conductivity of the graphene layers, which was quantified by monitoring the current–voltage characteristics at various NO₂ gas concentrations. The adsorption rate was found to be more rapid than the desorption rate, which can be attributed to the reaction occurred on the surface of the graphene layer. The sensitivity was 9% when an ambient of 100 ppm NO₂ was used. Graphene-based gas sensors showed fast response, good reversibility, selectivity and high sensitivity. Optimization of the sensor design and integration with UV-LEDs and Silicon microelectronics will open the door for the development of nano-sized gas sensors that are extremely sensitive.     

Fe3O4@MIL-100(Fe) modified ZnS nanoparticles with enhanced sonocatalytic degradation of tetracycline antibiotic in water

Sonocatalysis has attracted excellent research attention to eradicate hazardous pollutants from the environment effectively. This work synthesised an organic/inorganic hybrid composite catalyst by coupling Fe₃O₄@MIL-100(Fe) (FM) with ZnS nanoparticles using the solvothermal evaporation method. Remarkably, the composite material delivered significantly enhanced sonocatalytic efficiency for removing tetracycline (TC) antibiotics in the presence of H₂O₂ compared to bare ZnS nanoparticles. By adjusting different parameters such as TC concentration, catalyst dosage and H₂O₂ amount, the optimized composite (20 %Fe₃O₄@MIL-100(Fe)/ZnS) removed 78.25% antibiotic in 20 min at the cost of 1 mL of H₂O₂. These much superior activities are attributed to the efficient interface contact, effective charge transfer, accelerated transport capabilities and strong redox potential for the superior acoustic catalytic performance of FM/ZnS composite systems. Based on various characterization, free radical capture experiments and energy band structures, we proposed a mechanism for the sonocatalytic degradation of tetracycline based on S-scheme heterojunctions and Fenton like reactions. This work will provide an important reference for developing ZnS-based nanomaterials to study sonodegradation of pollutants.     

The Sr content influence on the positive magnetoresistance in La1-xSrxMnO3/Si heterojunctions

<正>We fabricated La_(1-x)Sr_xMnO_3/Si(LSMO/Si) heterojunctions with different Sr doping concentrations(x = 0.1, 0.2,0.3) in LSMO and studied the Sr content influence on magnetoresistance(MR) ratio.The hetero junctions show positive MR and high sensitivity of MR ratio in a low applied magnetic field.The MR ratio is dependent on Sr content and the low Sr doping in LSMO causes a large positive MR in LSMO/Si junctions.The MR ratio for 0.1 Sr doping in the LSMO/Si heterostructure is 116%in 100 Oe(1 Oe=79.5775 A/m) at 210 K.The mechanism for the positive MR dependence on the doping density is considered to be the competition between the tunneling rate of electrons in e_g~1↑to t_(2g)↓band and that to e_g~2↑band at the interface region of LSMO.The experimental results are in agreement with those observed in La_(0.9)Sr_(0.1)MnO_3/SrNb_(0.01)Ti_(0.99)O_3 p-n junction.The results indicate that choosing low doping concentration to improve the low field sensitivity of the heterojunction devices is a very efficacious method.     

Optical properties of some fluoride compounds and their application to dosimetry

Effects of β, X and VUV irradiation on the optical properties have been studied in various simple and complex fluoride crystals by using optical absorption, X- and UV-excited luminescence (XL and PL), thermoluminescence (TL) and photo-transferred TL (PTTL) techniques. In most tested crystals, the main TL peaks with the same thermal activation energies appear after VUV as well as after X or β irradiation, thus indicating that the same traps are induced by the different types of radiation. The TL excitation spectra generally show absorption maxima on the long wavelengths tail of the fundamental absorption. Within this study, various dosimetric properties, as well as the possible application of the crystals as sensitive radiation detectors and dosimeters for the VUV have also been investigated. The TL sensitivities of the various studied materials have been compared to that of the classic dosimeter TLD-100 (LiF:Mg,Ti). For example, the sensitivity of SrF₂:Pr³⁺ has been found to be the highest among the examined crystals and at a dose of 90 Gy its response is higher by a factor of ～3 than that of TLD-100. The sensitivity of CsGd₂F₇:Pr³⁺ and KYF₄:Pr³⁺ are slightly higher than that of TLD-100, whereas that of nanostructured CaF₂:ZnO crystals is about twice that of TLD-100, but the sensitivity of LiF:Eu is much lower. The SrF₂:Pr³⁺ crystals also showed some important dosimetric properties.     

Metallic Nanocrystallites-Coated Piezoelectric Quartz for Applications in Gas Sensing

This article reports the gas-sensing capability of nanocrystalline (NC) transition metal-coated piezoelectric quartz crystal (PQC). NC transition metal particles of Pd and Ag with particles size of 10–15 nm, while Pt and Au are 20–25 nm are used. The NC particles deposited on the quartz substrate adsorbs gaseous pollutants, thereby increasing the weight of the quartz substrate and decreasing its vibration frequency. We have found that transition metals, Pd, Pt, Au, and Ag in particular, show good sensitivity for NH₃-detection; the maximum frequency change occurs at 150°C for Pd and Pt and at 100°C for Au and Ag. The NC Pd- and NC Pt-coated PQC also show good sensitivity for CO₂-detection at 150°C. Likewise, the NC Au-coated PQC shows very good sensitivity for NO₂-detection but at a higher temperature (180^°C). The frequency change as a function of the pollutant gas concentration ( f-curve) follows the Langmuir adsorption isotherm (unimolecular adsorption) except in the case of NC Pd-coated PQC under NH₃ and NC Au-coated PQC under NO₂. The f-curve for the NC Pd-coated PQC is convex with respect to the NH₃ concentration axis. The f-curve for the NC Au-coated PQC is convex in the low NO₂ concentration region, and concave in the high NO₂ concentration region. Both curves indicate multi-molecular adsorption, Type III and Type V adsorption, respectively. Therefore, the good sensitivity and stability of these gas sensors can be attributed to physical adsorption of the pollutant gases as a result of van der Waals attraction.     

Effects of composition and transparency on photo and radioluminescence of Y2O3:Eu complexes

A solid state-based method using a hot reaction chamber is applied to the synthesis of Y₂O₃:Eu particles containing Eu from 0 to 5 mol%. The produced powders are studied using X-ray diffraction (XRD), scanning electron microscopy and transmission electron microscopy (TEM), as well as photoluminescence (PL) and radioluminescence tests. TEM and XRD results revealed the powder to be mono-disperse and in the form of a solid solution. The PL of Y₂O₃:Eu powder depends on both the concentration quenching effect (due to an excess of Eu concentration) and the surface luminescence effect (depicted by a higher surface area induced by the large phosphor concentration in the solution or smaller particle sizes). A ²²Na gamma source is used to compare the recorded count rates for four Y₂O₃:Eu scintillator materials with different concentrations of Eu. Each scintillator composition is examined in four forms: solid pellets with a high volume porosity and three aqueous solutions of Y₂O₃:Eu particles of the different scintillator materials at concentrations of 25, 50 and 100 mg/mL. The radioluminescence results indicated that increasing the transparency and/or the amount of Eu mol% of the scintillators increases the net average counts.     

An Immunonanogold Resonance Scattering-Quenching Probe for Rapid and Sensitive Assay of Microalbumin

A novel and sensitive immunonanogold resonance scattering (RS) spectral probe was obtained for rapid detection of microalbumin (Malb), using 10 nm gold nanaoparticle to label goat anti-human Malb. It was based on that the gold-labeled anti-Malb took place nonspecific aggregation and exhibited a strong RS peak at 577 nm in pH 5.2 C₆H₈O₇–Na₂HPO₄ buffer solution containing polyethylene glycol (PEG), and the immunocomplex formed after specific reaction of gold-labeled anti-Malb with Malb, which led to a decrease in the intensity of RS peak at 577 nm considerably. The decreased RS intensity at 577 nm (ΔI _577nm) was linear to the concentration of Malb in the range of 4–128 ng/mL, with a detection limit of 3.2 ng/mL. The proposed method was applied to detect Malb in healthy human urine samples with satisfactory results.     

Toxicity of amorphous silica nanoparticles in mouse keratinocytes

The present study was designed to examine the uptake, localization, and the cytotoxic effects of well-dispersed amorphous silica nanoparticles in mouse keratinocytes (HEL-30). Mouse keratinocytes were exposed for 24 h to various concentrations of amorphous silica nanoparticles in homogeneous suspensions of average size distribution (30, 48, 118, and 535 nm SiO₂) and then assessed for uptake and biochemical changes. Results of transmission electron microscopy revealed all sizes of silica were taken up into the cells and localized into the cytoplasm. The lactate dehydrogenase (LDH) assay shows LDH leakage was dose- and size-dependent with exposure to 30 and 48 nm nanoparticles. However, no LDH leakage was observed for either 118 or 535 nm nanoparticles. The mitochondrial viability assay (MTT) showed significant toxicity for 30 and 48 nm at high concentrations (100 μg/mL) compared to the 118 and 535 nm particles. Further studies were carried out to investigate if cellular reduced GSH and mitochondria membrane potential are involved in the mechanism of SiO₂ toxicity. The redox potential of cells (GSH) was reduced significantly at concentrations of 50, 100, and 200 μg/mL at 30 nm nanoparticle exposures. However, silica nanoparticles larger than 30 nm showed no changes in GSH levels. Reactive oxygen species (ROS) formation did not show any significant change between controls and the exposed cells. In summary, amorphous silica nanoparticles below 100 nm induced cytotoxicity suggest size of the particles is critical to produce biological effects.     

Synthesis and gas sensing properties of perovskite CdSnO<Subscript>3</Subscript> nanoparticles

The CdSnO₃ semiconducting oxide that can be used as a gas-sensitive material for detecting ethanol gas is reported in this paper. CdSnO₃ nanoparticles were prepared by a chemical co-precipitation synthesis method, in which the preparation conditions were carefully controlled. The n-type gas-sensing semiconductors were obtained from the as-synthesized powders calcined at 600°C for 1 h. The phase and microstructure of the obtained nanoparticles were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and Brunauer–Emmett–Teller (BET) method with a gas adsorption analyzer. CdSnO₃ has a small particle size range of 30–50 nm and a high surface area of 9.12 m²/g, and a uniformity global shape. The gas sensitivity and operating temperature, and selectivity of CdSnO₃-based sensors were measured in detail. The gas sensors fabricated by CdSnO₃ nanoparticles had good sensitivity and selectivity to vapor of C₂H₅OH when working temperature at 267°C, the value of gas sensitivity at 100 ppm of C₂H₅OH gas can reach 11.2 times. Furthermore, gas-sensing mechanism was studied by using chromatographic analysis.     

高温超导台阶结YBCO dc-SQUID一阶平面梯度计

在10mm×10mm SrTiO₃(STO)台阶衬底上用单层YBa₂Cu₃ O_7-δ(YBCO)薄膜制备了dc-SQUID一阶平面梯度计,探测环面积约为33mm ²,基线长度d=45mm.该梯度计在无屏蔽条件下对地磁场有较好的屏蔽作用,共模抑 制比为14×10²,磁场梯度灵敏度为8PT/cmHz(白噪声区). 关键词： 台阶结 SQUID 平面梯度计     

The influence of heat exchange between a sensitive element and its surroundings on the specific detectivity of pyroelectric detectors

The specific detectivity of pyroelectric sensors at low frequencies is mainly influenced by the thermal conditions within the sensor. The temperature noise caused by heat exchange between the sensitive element and its surroundings is transformed into an increase of the dielectric loss due to electrothermal coupling. The complex normalized current responsivity is used to calculate the influence of thermal conditions. While the absolute value ¦T_R¦ gives the frequency response of the sensitivity, the additional dielectric loss tan δ_T is deduced from the imaginary part. The loss due to electrothermal coupling tan δ_T exceeds the dielectric intrinsic loss tan δ_i for most sensor structures within the frequency range up to 100 Hz. Thus, the maximum attainable specific detectivity of a pyroelectric sensor at normal operation frequencies is dependent on its construction rather than on the material parameter dielectric intrinsic loss tan δ_i which is frequently referred to. The effect of electrothermal coupling can be employed in sensors with reduced sensitivity at low frequencies as used for FTIR-devices.     

Concepts in high-frequency EPR — Applications to bio-inorganic systems

In this contribution we describe a high-frequency high-field EPR facility which has been developed at the University of Nijmegen. We present the design of a heterodyne quasi-optical bridge based on a millimeter-wave vector network analyzer as source and detection system. The mm-waves are transported in free-space through Gaussian beam optic elements and through a corrugated guide inside the resonator insert. The Fabri-Pérot (TEM_00n) resonator is coupled through a metallic mesh and because of its bimodal property it can be operated using orthogonal detection leading to substantial improvement in sensitivity. In the first stage of the project, a multifrequency CW-facility is realized covering the 100–500 GHz range. In our initial explorative experiments we demonstrate the advantages of HF-EPR of high-spin systems: Due to the large microwave quantum, transitions which would be undetectable at X-band due to the large zerofield splitting can now be observed in good sensitivity. As a model for biological high-spin systems a sample of metmyoglobin was measured at D-band (130 GHz). Theg = 5.9 perpendicular line from theS = 5/2 ferric heme was detected and its line-width was compared to data previously obtained at Q-, X-, S- and L-band. As a model for biological integer spin systems theS = 1 signal of Ni(II) in nickel Tutton salt (Ni(NH₄)₂(SO₄)₂) was studied at 35 and 130 GHz.