Development and characterization of bottom-viewed inductively coupled plasma-atomic emission spectrometry

In bottom-viewed inductively coupled plasma-atomic emission spectrometry (BV-ICP-AES), emission from the central channel of the plasma is measured axially from the bottom of the plasma. A straight quartz tube was used as a hollow light pipe (HLP) to collect plasma emission in this study. The HLP also serves as an injector for aerosols transport and injection into the ICP. The optical characteristics of HLPs with the original reflective surface and roughened outer surface are reported. The roughened HLP is effective in rejecting light beams that are not in line with the HLP. The transmission efficiency of the HLP, however, is high (> 70%) for light beams from a source that has the same dimension as the entrance of the HLP and is flush with the HLP. The HLP is effective in rejecting background emission from the core of the plasma that encircles the plasma central channel and yet efficient in light collection from the central channel of the plasma.     

激活CaO-MgO-SiO_2长余辉玻璃发光性质

报道了一种新型的Eu~(2+)离子激活硅酸盐玻璃,该玻璃组成为2CaO-MgO-3SiO_2-0.015Eu_2O_3(CMSE)。通过透射光谱、稳态荧光光谱、余辉光谱和热释光等技术手段对CMSE的发光性质进行了深入研究。研究发现CMSE可以被紫光和近紫外光激发,获得黄色长余辉发光。热释光曲线的分析表明,CMSE的长余辉性质主要来自于玻璃基质中陷阱深度为0.83 e V左右的定域能级。研究认为对CMSE发光性质的研究有利于开发新型稀土离子激活近紫外激发LED用硅酸盐玻璃发光材料。     

Glucose challenge metabolomics implicates the change of organic acid profiles in hyperlipidemic subjects

Hyperlipidemia (HLP) is a major risk factor of diabetes and cardiovascular disease. Here, we applied gas chromatography–mass spectrometry to study differences in postprandial organic acid profiles in healthy and HLP subjects. In fasting status, six intermediates of the tricarboxylic acid cycle showed significant differences in HLP and healthy controls (P < 0.05). The percentage changes of 17 metabolites including three intermediates of the tricarboxylic acid cycle were significantly different during the oral glucose tolerance test. Postprandial changes in ethylmalonic acid and pimelic acid were negatively associated with HOMA-IR (homeostasis model assessment of insulin resistance; all P < 0.05) in the HLP group. Postprandial metabolism of organic acid profiles revealed energy metabolism perturbations in HLP. Our findings provide new insights into the complex physiological regulation of HLP postprandial metabolism.     

小分子多肽HLP核素示踪分析方法研究

本研究旨在建立HLP的放射性碘示踪分析方法, 为HLP及小分子多肽类化合物药代动力学研究提供可行的途径.     

Long Lasting Phosphorescence Properties and Multi-peak Fitting on Thermoluminescence of Red LaAlO3: Eu3+ Phosphor

Red long lasting phosphorescence(LLP) was firstly observed in LaAlO₃:Eu³⁺ phosphor synthesized by solid state method at 1773 K. It reveals that the Eu³⁺ ions occupy the asymmetric La³⁺ sites, resulting in the orange-red emission of Eu³⁺. The LLP of the optimum LaAlO₃:0.6%Eu³⁺ sample can come to about 2000 s according to a definition of 0.32 mcd/m². The LLP decay curve can not be fitted even by a function of three exponential terms, due to the complicated retrapping process of carriers. The result of a classical multi-peak fitting method on thermoluminescence reveals that the excellent LLP performance of LaAlO₃:Eu³⁺ material originates from the rich distribution of shallow traps(E=0.7875 eV).     

Efficient removal of MB dye using litchi leaves powder adsorbent: Isotherm and kinetic studies

Removal of Methylene Blue (MB) dye using Litchi Leaves Powder (LLP) material was carried out in batch mode. Effect of the mass of the adsorbent (0.1–2.5 g/L), pH of the solution (2−12), starting concentration of MB dye (50–150 mg/L), ionic strength using NaCl (0.1–0.5 M) as an electrolyte, contact time (0–60 min) on the adsorption of MB dye was studied. To calculate pH at which LLP material surface becomes neutral point of zero charge (pH_pzc) is also determined and found to be 6.48. Removal process best fit in the pseudo-second-order kinetic model as indicated by its higher R² value (0.999). Isotherm models (Freundlich and Langmuir) were fitted to the data obtained from the experiment to understand the adsorption behaviour. Result shows that experimental data were fitted to the both isotherm models (Freundlich and Langmuir) as indicated by higher R² value for both Freundlich (0.991) and Langmuir (0.994) model, and it was determined that LLP has a maximum adsorption capacity of 119.76 mg/g.     

超高效液相色谱-电喷雾串联质谱法同时测定猪肝中非甾体类抗炎药残留

采用超高效液相色谱-四极杆串联质谱仪(UPLC-MS/MS)同时测定了猪肝中18种非甾体类抗炎药(NSAIDs)的残留量.对NSAIDs多残留同时提取、净化技术进行了研究,对UPLC-MS/MS检测参数进行了优化.均质后的猪肝样品采用酸化乙腈提取,正己烷液-液分配(LLP)脱脂,经硅胶固相萃取(SPE)柱净化后,采用UPLC-MS/MS电喷雾电离(ESI),多反应监测(MRM)模式检测,以保留时间和子离子比定性,外标法定量.方法检出限(LOD)为0.2～10 μg/kg;定量限(LOQ)为1.0～50 μg/kg.在添加浓度在1.0～200 μg/kg范围内,NSAIDs的回收率在53.8%～92.7%之间,相对标准偏差(RSD)小于10.3%.方法操作简便,对动物肌肉、内脏、鸡蛋及牛奶中NSAIDs残留的检测具有普遍适用性.     

Rare earth element patterns in lake sediments as studied by neutron activation analysis

Using instrumental neutron activation analysis, the vertical distribution of La, Ce, Nd, Sm, Eu, Tb, Yb and Lu was determined in 3 well dated sedimentary cores collected from Laguna Mar Chiquita, Argentina. Validation of the methodology was done using the Soil 7 (IAEA) reference material. The REE contents vary according to core location and lithological units, depending on the proportion of fluvial terrigenous components in the lake sediments. Lithologies with higher proportion of terrigenous components show higher REE concentrations, suggesting that the dominant REE carrier phase might be a detrital mineral. There is a consistent value of about 1.2 for (La/Yb)_N and (LREE/HREE)_N ratios for all sediments at the three sites, indicating a slight LREE enrichment in relation to the average shale NASC. Ce/Ce* values are close to 1.0, meaning that Ce behaves similarly to other light REE's.     

The role of excess Zn ions in improvement of red long lasting phosphorescence (LLP) performance of β-Zn3(PO4)2:Mn phosphor

Influences of excess Zn²⁺ ions and intrinsic defects on red (λ=616 nm) phosphorescence of β-Zn₃(PO₄)₂:Mn²⁺ are systematically investigated. It is clearly observed that red long lasting phosphorescence (LLP) properties of Mn²⁺, such as brightness and duration, are largely improved when excess Zn²⁺ ions are co-doped into the matrix. Photoluminescence (PL), LLP and thermoluminescence (TL) spectra indicate that Mn²⁺ ion acts as luminescent center whereas oxygen vacancy associated to Zn²⁺ ion plays a significant role in electron trap. The TL peak for oxygen vacancy is centered at 343 K, the depth of which is suitable for improvement in LLP performance of Mn²⁺ at room temperature. The possible mechanism for this phenomenon of red LLP of Mn²⁺ in β-Zn₃(PO₄)₂:Mn²⁺ with excess of Zn²⁺ is explained by means of a competitively trapping model.     

Determination of the level of the core of 2',5'-oligoadenylates by high performance liquid chromatography.

A simple and rapid method for analysis of the core of 2',5'-oligoadenylates, mainly based on the use of high performance liquid chromatography (HPLC), is described. Perchloric acid extracts of tissues or cells were first treated with nuclease P1. Portions of the extracts were then digested with alkaline phosphatase. HPLC analysis of the extracts was performed on a column system composed of an Ultrasphere ODS precolumn (4.6 x 45 mm) and an Ultrasphere Octyl column (4.6 x 250 mm) by stepwise elution using a 50 mM ammonium phosphate buffer, pH 7, containing 3.5 and 7% methanol. Three species of the core of 2',5'-oligoadenylates (dimer, trimer and tetramer) from a number of samples were eluted separately with 7% methanol, and the concentration of each core was directly estimated using constant values calculated with the standard core. The level of the core of 2',5'-oligoadenylates in tissues and cells determined by our method is similar to that reported by other authors who used biological, radiobinding or radioimmunological assays.     

Investigation of Symphytum cordatum alkaloids by liquid-liquid partitioning, thin-layer chromatography and liquid chromatography-ion-trap mass spectrometry

From the alkalised crude extract of Symphytum cordatum (L.) W.K. roots, pyrrolizidine alkaloids (PAs) were extracted as free tertiary bases and polar N-oxides in a merely one-step liquid-liquid partitioning (LLP) in separation funnel and subsequently pre-fractionated by preparative multiple-development (MD) thin-layer chromatography (TLC) on silica gel plates. In this way three alkaloid fractions of different polarities and retention on silica gel plates were obtained as: the most polar N-oxides of the highest retention, the tertiary bases of medium retention, and diesterified N-oxides of the lowest retention. The former fraction was reduced into free bases by sodium hydrosulfite and purified by LLP on Extrelut-NT3 cartridge. It was further analysed together with the two other fractions by high-performance liquid chromatography (HPLC)-ion-trap mass spectrometry with atmospheric pressure chemical ionization (APCI) interface on XTerra C₁₈ column using a gradient elution. Based on MSⁿ spectra, 18 various alkaloids have been tentatively determined for the first time in this plant as the following types of structure: echimidine-N-oxide (three diasteroisomers), 7-sarracinyl-9-viridiflorylretronecine (two diasteroisomers), echimidine (two diasteroisomers), lycopsamine (two diasteroisomers), dihydroechinatine-N-oxide, dihydroheliospathuline-N-oxide, lycopsamine-N-oxide (three diasteroisomers), 7-acetyllycopsamine-N-oxide, symphytine-N-oxide (two diasteroisomers) and 2″,3″-epoxyechiumine-N-oxide.     

Building blocks for N-type molecular and polymeric electronics. Perfluoroalkyl- versus alkyl-functionalized oligothiophenes (nTs; n = 2-6). Systematic synthesis, spectroscopy, electrochemistry, and solid-state organization

The synthesis, comparative physicochemical properties, and solid-state structures of five oligothiophene (nT) series differing in substituent nature and attachment, regiochemistry, and oligothiophene core length (n) are described. These five series include the following 25 compounds: (i) alpha,omega-diperfluorohexyl-nTs 1 (DFH-nTs, n = 2-6), (ii) beta,beta'-diperfluorohexyl-nTs 2 (isoDFH-nTs, n = 2-6), (iii) alpha,omega-dihexyl-nTs 3 (DH-nTs, n = 2-6), (iv) beta,beta'-dihexyl-nTs 4 (isoDH-nTs, n = 2-6), and (v) unsubstituted oligothiophenes 5 (alphanTs, n = 2-6). All new compounds were characterized by elemental analysis, mass spectrometry, and multinuclear NMR spectroscopy. To probe and address quantitatively how the chemistry and regiochemistry of conjugated core substitution affects molecular and solid-state properties, the entire 1-5 series was investigated by differential scanning calorimetry, thermogravimetric analysis, and optical absorption and emission spectroscopies. Single-crystal X-ray diffraction data for several fluorocarbon-substituted oligomers are also presented and compared. The combined analysis of these data indicates that fluorocarbon-substituted nT molecules strongly interact in the condensed state, with unit cell level phase separation between the aromatic core and fluorocarbon chains. Surprisingly, despite these strong intermolecular interactions, high solid-state fluorescence efficiencies are exhibited by the fluorinated derivatives. Insight into the solution molecular geometries and conformational behavior are obtained from analysis of optical and variable-temperature NMR spectra. Finally, cyclic voltammetry data offer a reliable picture of frontier MO energies, which, in combination with DFT computations, provide key information on relationships between oligothiophene substituent effects and electronic response properties.     

Separation of63Ni traces from low and medium level radioactive wastes produced during the operation of nuclear power reactors

The classification of low and medium level radioactive wastes produced regularly by nuclear power plants is becoming ever more important in Mexico, after a few years of running the first of two units, 600 MeV each, in Laguna Verde nuclear power plant. This paper describes a method to separate and detect traces of the weak -emitter⁶³Ni, which is one of the activation products used to classify low and medium level radioactive wastes originating from the operation of nuclear power plants.     

Separation of Antibodies by Liquid-Liquid Aqueous Partition and by Liquid-Liquid Partition Chromatography

In this review, we describe the use of liquid-liquid aqueous partition as a method for the separation of antibodies. Water-based two-phase systems made up of polyethylene glycol and dextran have, by far, been the most frequently used systems. The distribution of a molecule in these systems depends on its exposed surface properties and is described by its partition coefficient. The separation may be performed in a single step in a batch experiment or in several steps using various forms of automated counter-current extraction methods, referred to in this review as liquid-liquid partition (LLP). The sensitivity and selectivity of the two-phase technique can be considerably improved by employing a column chromatographic approach, liquid-liquid partition chromatography (LLPC). In LLPC, the bottom-phase of the two-phase system is adsorbed onto a support and packed into a column which is eluted with the corresponding top-phase. In the first part of this review, the methodology behind UP and UPC is described and outlined in broader terms, before the properties and prestanda of the two approaches are compared. In the second part, the results obtained by LLP and LLPC on antibodies are described in more detail. This review shows, that liquid-liquid aqueous partition is a powerful tool for antibody analysis, that is for purification and fractionation, detection and separation of conformational isomeric forms, examination of surface properties related to antigen specificities and for providing new interesting information about the events upon antigen-antibody complexation and about possible ligand-induced conformational changes.     

ZnO-B2O3∶Tb3+长余辉玻璃的发光性质

通过还原方法制备了Tb³⁺离子掺杂的硼酸锌玻璃，并观察到在254 nm紫外光激发后有明亮的绿色长余辉发光现象，余辉时间达6 h。通过激发与发射光谱、余辉光谱、余辉衰减曲线、热释光谱、热释光释出速率衰减曲线等得到的信息，研究了Tb³⁺离子掺杂的硼酸锌玻璃的发光性质。     

Pyridine-tert-nitrogen-phenol ligands: N,N,O-Type tripodal chelates for the [M(CO)3]+ core (M = Re, Tc)

The design rationale, synthesis, and preliminary radiolabeling evaluation of new N,N,O-type pyridyl- tert-nitrogen-phenol ligands for the [M(CO) 3] (+) core, where M = (99m)Tc or Re, are described. The capability of the ligands to bind this technetium core is initially demonstrated by using the cold surrogate [Re(CO) 3] (+). NMR studies of the relevant rhenium tricarbonyl complexes indicate the formation of either a monomeric or a possible dimeric complex with each phenolic O atom bridging between two metal centers. Labeling with [ (99m)Tc(CO) 3] (+) provided further insight into the differences in complex formation on the dilute, no carrier added, level compared to the macroscopic scale at which the Re (I) counterparts were made. These new tridentate, monoanionic ligands are competent chelates in binding the [ (99m)Tc(CO) 3] (+) core because radiolabeling yields ranged from 85 to 99% and the resulting complexes were stable to cysteine and histidine challenges for as long as 24 h.     

A novel thiophene-fused polycyclic aromatic with a tetracene core: synthesis, characterization, optical and electrochemical properties

FeCl?-mediated oxidative cyclization was successfully used to construct an extended thiophene-pendant pyrene skeleton and synthesize a novel thiophene-fused polycyclic aromatic (THTP-C) with a tetracene core. The identity of the compound was confirmed by 1H-NMR, 13C-NMR, MS, and elemental analysis. Meanwhile, a single crystal of THTP-C was obtained and analyzed by X-ray single-crystal diffraction. THTP-C has a "saddle" shaped π-conjugated 1-D supramolecular structure, and favors highly ordered self-assembly by π-π interactions as evidenced by its concentration-dependent 1H-NMR spectra in solution. The optical properties of THTP-C were investigated by ultraviolet-visible (UV-Vis) and photoluminescence (PL) spectroscopy and its electrochemical properties were investigated by cyclic voltammetry (CV). The relatively large band gap (2.86 eV), low E(HOMO) level (-5.64 eV) and intermolecular π-π interactions imply that THTP-C has a high stability against photo-degradation and oxidation, and may be a promising candidate for stable hole-transporting materials.     

Hyperbranched polycarbosiloxane with dendritic boron cores: Synthesis,characterization, and structure regulation

The synthesis, characterization, and structure regulation of hyperbranched polycarbosiloxane with dendritic boron cores were realized in this paper. First, dendritic boron core was synthesized via hydroboration with borane dimethylsulfide and bis(allyloxy)dimethylsilane. Then, the hyperbranched polycarbosiloxanes with dendritic boron cores were synthesized via hydrosilylation with AB₂ type monomer of bis(allyloxy)methylsilane and dendritic boron cores. The molecular structures of the dendritic boron core and resulting hyperbranched polymers were characterized by using Fourier transform infrared spectroscopy, ¹H nuclear magnetic resonance, and ¹³C nuclear magnetic resonance spectroscopies. Size exclusion chromatography/multiangle laser light scattering analysis reveals that the structures of hyperbranched polycarbosiloxane can be regulated effectively by incorporation of functional dendritic boron cores. Compared with hyperbranched polycarbosiloxane of the same molecular weight level, the hyperbranched polycarbosiloxane with dendritic boron cores presents narrower molecular weight distribution as well as much smaller hydrodynamic radius and intrinsic viscosity. Thermalgravimetric analyzer analysis indicates that both the decomposition temperature and ceramic yields are increased as the results of the incorporation of dendritic boron cores into hyperbranched polycarbosiloxane. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 3930–3941, 2006     

Peak shape analysis of Ag 3d core‐level X‐ray photoelectron spectra of Au@Ag core‐shell nanoparticles using an asymmetric Gaussian–Lorentzian mixed function

This article reports on the peak shape analysis of X‐ray photoelectron spectra of gold‐silver core‐shell (Au@Ag) nanoparticles (NPs) using an asymmetric Gaussian–Lorentzian mixed function. Unlike Ag NPs, Au@Ag NPs have no oxide peak and show asymmetric line shape with a high energy tail in Ag 3d core‐level spectra. A monotonic increase in the Ag 3d binding energy and a decrease in the degree of asymmetry with increasing the Ag shell thickness were observed supporting the occurrence of charge transfer from Au core to Ag shell. Copyright © 2012 John Wiley & Sons, Ltd.     

Geometry of simple molecules: nonbonded interactions, not bonding orbitals, and primarily determine observed geometries.

The forces responsible for the observed geometries of the YX(3) (Y = N or P; X = H, F, or Cl) molecules were studied through ab initio computations at the HF-SCF/6-31G level. The calculated molecular orbitals were grouped as contributing primarily to (a) the covalent bonds, (b) the terminal atom nonbonding electrons (for X = F or Cl), and (c) the central atom nonbonding electrons. This grouping was accomplished through 3-D plotting and an atomic population analysis of the molecular orbitals. The molecules were then moved through a X-Y-X angular range from 90 degrees to 119 degrees, in four or five degree increments. Single-point calculations were done at each increment, so as to quantify the energy changes in the molecular orbital groups as a function of geometry. These calculations show that the nonbonding electrons are much more sensitive to geometry change than are the bonding orbitals, particularly in the trihalide compounds. The molecular orbitals representing the nonbonding electrons on the terminal atoms (both valence and core electrons) contribute to the spreading forces, as they favor a wider X-Y-X angle. The contracting forces, which favor a smaller X-Y-X angle, consist of the orbitals comprising the nonbonding electrons on the central atom (again, both valence and core electrons). The observed geometry is seen as the balance point between these two sets of forces. A simple interaction-distance model of spreading and contracting forces supports this hypothesis. Highly linear trends are obtained for both the nitrogen trihalides (R(2) = 0.981) and phosphorus trihalides (R(2) = 0.992) when the opposing forces are plotted against each other. These results suggest that a revision of the popular conceptual models (hybridization and VSEPR) of molecular geometry might be appropriate.