A multi-instrumental approach to identify and purify very small embryonic like stem cells (VSELs) from adult tissues

We employed several complementary cell image analytical methods including ImageStream system (ISS analysis) and molecular approaches to identify and purify from adult murine organs a population of very small embryonic like stem cells (VSELs). These cells are (i) small in size, (ii) possess high cytoplasmic/nuclear ratio, (iii) contain primitive unorganized euchromatin, (iv) in mice are found among Sca-1⁺ Lin^? CD45^? cells and in humans among CD133⁺ CXCR4⁺ CD34⁺ Lin^? CD45^? cells and (v) express embryonic markers such as Oct-4 protein in nuclei and SSEA antigens on the surface. In mice the highest number of these cells resides in brain, kidney, pancreas and bone marrow. Data from our laboratory indicate that VSELs are most likely a population of germ line/epiblast-derived pluripotent stem cells, that is deposited during organogenesis in developing tissues as a source of tissue committed stem cells and that the number of these cells decreases with the age. We believe that VSELs could be harnessed as a source of pluripotent stem cells for regenerative medicine.     

Low-density core-shell composite hollow microspheres with tunable magnetic properties

Low-density (about 0.9 g/cm³) composite core-shell hollow microspheres with tunable magnetic properties were fabricated by Ni-Fe-P deposition on hollow glass microspheres (HGM) with modified electroless plating process. The effects of mole ratio of Fe²⁺/Ni²⁺, concentration of the reducer and pH value of the solution on the magnetic properties of the products were investigated. In conclusion, the increase in the mole ratio of Fe²⁺/Ni²⁺ and pH value of the solution could improve the soft magnetic properties of composite microspheres remarkably, while the increase in the concentration of NaH₂PO₂ had the opposite effect. The as-obtained metallic shells were amorphous and the crystallization got better with increased annealing temperature after plating. In addition, the saturation intensity of the composite microspheres was enhanced monotonically by increasing the annealing temperature. This work provided a facile and effective strategy to fabricate core-shell composite hollow microspheres with tailored magnetic properties.     

Synthesis and studies of trisubstituted biphthalonitrile/Fe<Subscript>3</Subscript>O<Subscript>4</Subscript> magnetic hybrid microspheres

New trisubstituted biphthalonitrile/magnetite (TSB/Fe₃O₄) magnetic hybrid microspheres were synthesized from TSB and FeCl₃ · 6H₂O using the method of one-stage thermal temperature crystallization of solvents. The morphology and structure of magnetic hybrid microspheres were inspected using a scanning electron microscope, IR Fourier spectroscopy, and X-ray diffraction. It was found that the grown TSB/Fe₃O₄ magnetic hybrid microspheres represent spherical particles with an average size of ~137 nm and a small size spread. The size and size distribution of magnetic hybrid microspheres can be controlled by a small change in the ratio of TSB and Fe³⁺ ion contents in the microsphere. TSB/Fe₃O₄ hybrid microspheres exhibit a rather high saturation magnetization (58.16 emu g^–1) and new microwave electromagnetic properties, i.e., lower (in comparison with published) dielectric losses at low frequencies; magnetic losses are increased obviously due to an increase in the TSB content. Furthermore, it is detected that magnetic hybrid microspheres absorb microwaves, and strong reflection losses in a wide frequency range are established. The effective reflection loss of–31 dB is obtained in the microwave range from 2 to 16 GHz due to TSB content variations. Wide absorption properties of microwaves along with regular spherical shape and excellent magnetic properties offer wide opportunities for various applications of TSB/Fe₃O₄ magnetic hybrid microspheres as functional materials.     

High accuracy calculation of the hydrogen negative ion in strong magnetic fields

Using a full configuration-interaction method with Hylleraas-Gaussian basis function, this paper investigates the 1¹0⁺, 1¹(–1)⁺ and 1¹(–2)⁺ states of the hydrogen negative ion in strong magnetic fields. The total energies, electron detachment energies and derivatives of the total energy with respect to the magnetic field are presented as functions of magnetic field over a wide range of field strengths. Compared with the available theoretical data, the accuracy for the energies is enhanced significantly. The field regimes 3 < γ < 4 and 0.02 < γ < 0.05, in which the 1¹(–1)⁺ and 1¹(–2)⁺ states start to become bound, respectively, are also determined based on the calculated electron detachment energies.     

Improved quantitative analysis of Cu(In,Ga)Se2 thin films using MCs+-SIMS depth profiling

The chalcopyrite semiconductor, Cu(InGa)Se₂ (CIGS), is popular as an absorber material for incorporation in high-efficiency photovoltaic devices because it has an appropriate band gap and a high absorption coefficient. To improve the efficiency of solar cells, many research groups have studied the quantitative characterization of the CIGS absorber layers. In this study, a compositional analysis of a CIGS thin film was performed by depth profiling in secondary ion mass spectrometry (SIMS) with MCs⁺ (where M denotes an element from the CIGS sample) cluster ion detection, and the relative sensitivity factor of the cluster ion was calculated. The emission of MCs⁺ ions from CIGS absorber elements, such as Cu, In, Ga, and Se, under Cs⁺ ion bombardment was investigated using time-of-flight SIMS (TOF-SIMS) and magnetic sector SIMS. The detection of MCs⁺ ions suppressed the matrix effects of varying concentrations of constituent elements of the CIGS thin films. The atomic concentrations of the CIGS absorber layers from the MCs⁺-SIMS exhibited more accurate quantification compared to those of elemental SIMS and agreed with those of inductively coupled plasma atomic emission spectrometry. Both TOF-SIMS and magnetic sector SIMS depth profiles showed a similar MCs⁺ distribution for the CIGS thin films.     

Preparation and characterization of magnetic P(St-co-MAA-co-AM) microspheres

In this study, magnetic polymer-coated microspheres were prepared by the microemulsion polymerization of styrene (St), methacrylic acid (MAA), acryamide (AM) in the presence of emulsifiers with the size of 1–5 μm. The magnetic material (i.e. Fe₃O₄) coated with oleic acid used in the preparation of the microspheres was synthesized in a classical co-precipitation procedure. The morphological and magnetic properties of the microspheres were investigated by different techniques (i.e. TEM, TGA, optical microscopy, vibrating sample magnetometer). The results indicated that the magnetic microspheres were superparamagnetic, well shaped spheres, mono-dispersed with abundant functional groups on the surfaces of the magnetic microspheres and good thermal stability. The microspheres could be linked well with the avidin and FITC antibody.     

Synthesis of immunomagnetic nanoparticles and their application in the separation and purification of CD34 hematopoietic stem cells

The silica-coated superparamagnetic nanoparticles with the uniform diameter of about 60 nm were synthesized by reverse microemulsions method. And the magnetic nanoparticles were modified with N-(2-aminoethyl)-3-aminopropyltrimethoxysilane (AEAPS). The immunomagnetic nanoparticles were then successfully prepared by covalently immobilizing anti-CD34⁺ monoclonal antibodies to the surface of amino silane modified magnetic particles. The cell separation results showed that the synthesized immunomagnetic nanoparticles could rapidly and conveniently separate the CD34⁺ cells with high efficiency and specificity than normal ones. The surface morphology of separated target cells was examined by scanning electron microscope (SEM). Atomic force microscope (AFM) also characterized the magnetic materials on the surface of the separated target cells for the first time, which further confirmed that the target cells were separated by the immunomagnetic nanoparticles. The viability of the separated cells was studied by culturing method and Beckman Vi-cell viability analyst. Therefore, our experiments provided a new, direct, rapid mode to separate target cells.     

Immobilization of silver nanoparticles on silica microspheres

The silver nanoparticles (Ag NPs) have been immobilized onto silica microspheres through the adsorption and subsequent reduction of Ag⁺ ions on the surfaces of the silica microspheres. The neat silica microspheres that acted as the core materials were prepared through sol–gel processing; their surfaces were then functionalized using 3-mercaptopropyltrimethoxysilane (MPTMS). The major aims of this study were to immobilize differently sized Ag particles onto the silica microspheres and to understand the mechanism of formation of the Ag nano-coatings through the self-assembly/adsorption behavior of Ag NPs/Ag⁺ ions on the silica spheres. The obtained Ag NP/silica microsphere conglomerates were characterized by field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), and energy-dispersive spectroscopy (EDS). Their electromagnetic wave shielding effectiveness were also tested and studied. The average particle size of the obtained Ag NPs on the silica microsphere was found that could be controllable (from 2.9 to 51.5 nm) by adjusting the ratio of MPTMS/TEOS and the amount of AgNO₃.     

Fabrication of surface‐enhanced Raman scattering‐active ZnO/Ag composite microspheres

We show in this paper how zinc oxide (ZnO)/silver (Ag) composite microspheres can be prepared by the reduction of Ag(NH₃)₂⁺ with the reducing agent formaldehyde in aqueous solution on the surface of ZnO microspheres. During the preparation, Sn²⁺ was absorbed on the surface of ZnO microspheres for sensitization and activation, and then Ag(NH₃)₂⁺ was reduced to Ag nanoparticles by the reducing agent to obtain ZnO/Ag composite microspheres. SEM and TEM images revealed silver nanoparticles with a diameter ranging from tens to 100 nm. X‐Ray photoelectron spectra (XPS), X‐ray diffraction (XRD) patterns and UV‐vis spectra were used to characterize the structure of the ZnO/Ag composite microspheres. The origin of the surface‐enhanced Raman scattering properties was traced to the surface of the ZnO/Ag composite microspheres. The enhancement factor was estimated in detail, and the enhancement mechanism for the SERS effect was also investigated. Copyright © 2007 John Wiley & Sons, Ltd.     

Die ZerstÄubung von Kupfer durch Edelgas-Ionen im Energiebereich von 100 keV bis 1 MeV als Funktion des Einfallswinkels

Using a 1.3MeV Van de Graaff-accelerator the sputtering ratioS of polycristalline copper bombarded by Ne⁺-, Ar⁺-, Kr⁺- and Xe⁺-ions was measured as a function of the angle of incidence in the range from 0? to 45?. The ion-energy was varied from 100 keV to 1 MeV. The sputtering ratio was found to increase with bombarding angle asS=S(0?)· (2- cos α)/cos α for Ne⁺-, Ar⁺- and Kr⁺-ions and asS=S(0?)/cos^3/2 α for Xe⁺-ions. The increase of the sputtering ratio was found to be independent of the ion-energy.     

Evaluation of the impact of chitosan/DNA nanoparticles on the differentiation of human naive CD4+ T cells

Chitosan (CS) is one of the most widely studied polymers in non-viral gene delivery since it is a cationic polysaccharide that forms nanoparticles with DNA and hence protects the DNA against digestion by DNase. However, the impact of CS/DNA nanoparticle on the immune system still remains poorly understood. Previous investigations did not found CS/DNA nanoparticles had any significant impact on the function of human and murine macrophages. To date, little is known about the interaction between CS/DNA nanoparticles and naive CD4⁺ T cells. This study was designed to investigate whether CS/DNA nanoparticles affect the initial differentiation direction of human naive CD4⁺ T cells. The indirect impact of CS/DNA nanoparticles on naive CD4⁺ T cell differentiation was investigated by incubating the nanoparticles with human macrophage THP-1 cells in one chamber of a transwell co-incubation system, with the enriched human naive CD4⁺ T cells being placed in the other chamber of the transwell. The nanoparticles were also co-incubated with the naive CD4⁺ T cells to explore their direct impact on naive CD4⁺ T cell differentiation by measuring the release of IL-4 and IFN-?? from the cells. It was demonstrated that CS/DNA nanoparticles induced slightly elevated production of IL-12 by THP-1 cells, possibly owing to the presence of CpG motifs in the plasmid. However, this macrophage stimulating activity was much less significant as compared with lipopolysaccharide and did not impact on the differentiation of the naive CD4⁺ T cells. It was also demonstrated that, when directly exposed to the naive CD4⁺ T cells, the nanoparticles induced neither the activation of the naive CD4⁺ T cells in the absence of recombinant cytokines (recombinant human IL-4 or IFN-??) that induce naive CD4⁺ T cell polarization, nor any changes in the differentiation direction of naive CD4⁺ T cells in the presence of the corresponding cytokines.     

Control of branching ratio in the photofragmentation of DCl+ ions: Effect of initial vibrational state

Photofragmentation of DCl⁺ ions alternatively leads to the formation of D⁺ + Cl or Cl⁺ + D in competing reaction channels. The branching ratio of the product yields D⁺/Cl⁺ has been investigated theoretically by numerically solving coupled time dependent Schrödinger equations and experimentally by femtosecond (fs) dissociative ionization of DCl. The theoretical analysis shows that this branching ratio increases step-like at intensities, which characteristically depend on the initial vibrational state for nonresonant multiphoton excitation. In general the threshold decreases with increasing initial vibrational quantum number. Experimental studies exhibit a similar step-like behavior of the D⁺/Cl⁺ branching ratio. Here the intensity at which the step occurs characteristically depends on the chirp of the fs-laser pulses, suggesting that different chirp may lead to intermediate DCl⁺ ions differing in the effective vibrational quantum number.     

Effects of impurity Na ions on the structural and magnetic properties of Ni-Zn-Cu ferrite powders: An improvement for chemical coprecipitation method

Ni-Zn-Cu ferrite powders with nominal composition Ni_0.4−xZn_0.6Cu_xFe₂O₄ (x=0.00-0.20) were prepared via chemical coprecipitation method. X-ray diffractometer, vibrating sample magnetometer, scanning electron microscopy, inductively coupled plasma-atomic emission spectrometry and energy dispersive spectrum were used to study the effects of impurity Na⁺ ions on the structural and magnetic properties. As a result, it was found that the impurity Na⁺ ions affect the crystalline structures and magnetic properties greatly. Moreover, the heterogeneous distribution of impurity Na⁺ ions and the formation of Na compounds retard the phase formation and the grain growth of specimens. Our study also reveals that for the chemical coprecipitation method, a second washing process introduced after drying can eliminate the impurity Na⁺ ions effectually and thus helps in the formation of single-phase structure and the growth of grains, which is very important for the improvement of magnetic properties and the preparation of ferrites via chemical coprecipitation method.     

Preparation of immunomagnetic nanoparticles and their application in the separation of mouse CD34 hematopoietic stem cells

The magnetic nanoparticles with a diameter of about 60 nm were synthesized by coprecipitation from ferrous and ferric iron solutions and coated with silica. Then the nanoparticles were modified with N-(2-aminoethyl)-3-aminopropyltrimethoxysilane (AEAPS) in order to immobilize anti-CD34⁺ monoclonal antibodies to the surface of modified magnetic particles. The results of transmission electron microscope (TEM) and Fourier transformed infrared (FT-IR) indicated that the nanoparticles were successfully prepared. Scanning electron microscope (SEM) photo confirmed that the mouse CD34⁺ cells (cells expressing CD34) were separated by the immunomagnetic nanoparticles. The viability of the separated cells was studied by hematopoietic colony-forming assay, the result of which showed that the target cells still had an ability of proliferation and differentiation. The application of the separated CD34⁺ cells was in testing the pharmacological effect of three samples isolated from enzyme-digested traditional Chinese medicine Colla corii asini.     

Measurement of the pion axial form factor from radiative decay

The decay π⁺→e⁺νγ has been measured by detecting the positron with a magnetic spectrometer and the photon with an array of NaI scintillators. Using CVC to compute the vector form factor from the π⁰ lifetime we use our data to determine the ratio γ of the axial-vector form factor to the vector form factor. With the best present value for the π⁰ lifetime (0.897±0.022±0.017)×10⁻¹⁶ s and F_V=(2.55 ±0.05)×10⁻² we obtain two solutions: γ=0.52 ±0.06, favored by a likelihood ratio greater than 8.5 against γ=−2.48±0.06.     

Photoproduction of charged pions on deuterium in the first resonance region

Photoproduction of π⁺ and π^? on deuterium has been measured in the photon energy range from 240 to 400 MeV and for pion c.m. angles between 15° and 180°. The pions were analysed in angle and momentum by a magnetic spectrometer. From the measured π^?/π⁺ ratio, corrected for Coulomb interactions in the final state, differential cross sections of the reaction γ+n→π^?+p were calculated. Together with the π⁺ photoproduction our data show no isotensor contribution. Comparison of our data with the recent experiments done on the inverse reaction shows no evidence of a violation of time reversal invariance. With the measured π⁺ photoproduction on deuterium, a test of the spectator model has been made. Using the closure-approximation of Chew and Lewis our data agree within a range of ±10%.     

Red-shift in the photostimulation of the X-ray storage phosphor RbBr:Ga+

Abstract

By means of magnetic circular dichroism of the optical absorption and photostimulated luminescence (PSL) the X-ray induced formation of F_A and F centres in RbBr:(Ga⁺, Li⁺) was investigated. It turnes out that RbBr:Ga⁺ co-doped with 1% Li⁺ in the melt reveals the largest red-shift of the PSL excitation bands to 790 nm, whereby the F_A to F ratio increases up to about 10% with decreasing X-ray dose. This is more than statistically expected (6%). High X-ray doses destroy F_A centres. However, up to 15% of the simultaneously generated F centres could be converted into the F_A species by appropriate bleaching with 633 nm light into the F centre absorption band.     

On-line orientation of bromine isotopes

Assignments for the principal Nilsson configuration in light β⁺-decaying bromine isotopes were proposed in a contribution to the OLNO-1 conference. These assignments were made on the basis of magnetic moments derived from the temperature dependence of anisotropies in daughter Se isotopes observed in the DOLIS-COLD facility at Daresbury. Anisotropy measurements have since been extended to a lower base temperature in^74m Br and^72g Br decay, leading to more stringent limits on the ground state moment of⁷²Br. The proposed π[312]3/2 configuration for⁷⁵Br has also now been confirmed by a measurement of the sign of its magnetic moment. This was done by observing the β-asymmetry in⁷⁵Br decay using high purity Si detectors mounted within the dilution refrigerator.     

Functionalized Biomimetic Magnetic Nanoparticles as Effective Nanocarriers for Targeted Chemotherapy

Novel MamC‐mediated biomimetic magnetic nanoparticles (BMNPs) are proposed as valuable carriers for targeted chemotherapy because of the size (36 ± 12 nm) and of surface properties conferred by MamC coating. They are super‐paramagnetic at room and body temperatures, have a large magnetic moment per particle, mediate hyperthermia, are cytocompatible, and, having a negative surface charge at physiological pH, can be efficiently coupled with DOXOrubicin (DOXO) and a monoclonal antibody (mAb) directed against the human Met/hepatocyte growth factor receptor (overexpressed in many cancers) displaying coupling stability, while releasing DOXO at acidic pH. This release can be enhanced by hyperthermia. The DOXO‐mAb‐BMNPs selectively recognize Met, bind efficiently to Met⁺ tumor cells, and discharge DOXO within their nuclei more efficiently than DOXO‐BMNPs, exerting cytotoxicity. These data represent proof of concept for future in vivo experiments in which the controlled dual targeting (mAb‐mediated and magnetic) approach and combined (chemotherapy and hyperthermia) therapy will be studied.     

非晶硅太阳电池的光伏检测磁共振研究

本文利用光伏检测磁共振(PDMR)方法初步研究了p⁺in⁺ a-Si:H太阳电池中与自旋状态有关的复合机制。研究表明太阳电池的制作工艺不同,相应的PDMR共振信号的线型和g因子亦不同,因而起支配作用的复合过程不同。根据PDMR结果讨论了a-Si:H膜的生长速度、衬底温度、本征层厚度等对太阳电池性能的影响。 关键词：