Study on the phosphorescence characterizations of palmatine chloride on the solid substrate and its interaction with ctDNA

The spectroscopic characterizations of solid substrate room temperature phosphorescence (SS-RTP) of palmatine (Pal) have been studied. Strong RTP signal at 615 nm can be induced on filter paper in the presence of TIAc. The interaction between calf thymus DNA (ctDNA) and Pal has been investigated at pH 6.90 using fluorescence, UV-vis, SS-RTP and cyclic voltammogram spectroscopy. Strong binding affinity of Pal with DNA is revealed from the absorption and fluorescence studies in the liquid state. With the addition of ctDNA, the fluorescence intensity of Pal is enhanced greatly and UV-vis spectra show no apparent hypochromicity and red shift, which indicates that Pal intercalates into ctDNA bases. However, this conclusion could not explain the phenomena from fluorescence polarization and denatured DNA measurements, which indicate that groove binding is at least the main binding mode. Binding constant and binding site size have been calculated to be 2.57 × 10⁴ L/mol and 0.16 based on Scatchard plot from fluorescence titration data. Groove binding has also been supported by phosphorescence lifetime and anion quenching experiments. Above studies demonstrate that there should exist intercalative binding and groove binding in the interaction of Pal and DNA. Furthermore, cyclic voltammogram study suggests that electrostatic binding exists at the same time exactly. Taken together, the binding model obtained in this study is mixed-mode.     

Approaching the gas-phase structures of [AgS8]+ and [AgS16]+ in the solid state

Upon treating elemental sulfur with [AgSbF(6)], [AgAl(hfip)(4)], [AgAl(pftb)(4)] (hfip=OCH(CF(3))(2), pftb =OC(CF(3))(3)) the compounds [Ag(S(8))(2)][SbF(6)] (1), [AgS(8)][Al(hfip)(4)] (2), and [Ag(S(8))(2)](+)[[Al(pftb)(4)](-) (3) formed in SO(2) (1), CS(2) (2), or CH(2)Cl(2) (3). Compounds 1-3 were characterized by single-crystal X-ray structure determinations: 1 by Raman spectroscopy, 2 and 3 by solution NMR spectroscopy and elemental analyses. Single crystals of [Ag(S(8))(2)](+)[Sb(OTeF(5))(6)](-) 4 were obtained from a disproportionation reaction and only characterized by X-ray crystal structure analysis. The Ag(+) ion in 1 coordinates two monodentate SbF(6) (-) anions and two bidentate S(8) rings in the 1,3-position. Compound 2 contains an almost C(4v)-symmetric [AgS(8)](+) moiety; this is the first example of an eta(4)-coordinated S(8) ring (d(Agbond;S)=2.84-3.00 A). Compounds 3 and 4, with the least basic anions, contain undistorted, approximately centrosymmetric Ag(eta(4)-S(8))(2) (+) cations with less symmetric eta(4)-coordinated S(8) rings (d(Agbond;S)=2.68-3.35 A). The thermochemical radius and volume of the undistorted Ag(S(8))(2) (+) cation was deduced as r(therm)(Ag(S(8))(2) (+))=3.378+ 0.076/-0.120 A and V(therm)(Ag(S(8))(2) (+))=417+4/-6 A(3). AgS(8) (+) and several isomers of the Ag(S(8))(2) (+) cation were optimized at the BP86, B3LYP, and MP2 levels by using the SVP and TZVPP basis sets. An analysis of the calculated geometries showed the MP2/TZVPP level to give geometries closest to the experimental data. Neither BP86 nor B3LYP reproduced the longer weak dispersive Agbond;S interactions in Ag(eta(4)-S(8))(2) (+) but led to Ag(eta(3)-S(8))(2) (+) geometries. With the most accurate MP2/TZVPP level, the enthalpies of formation of the gaseous [AgS(8)](+) and [Ag(S(8))(2)](+) cations were established as Delta(f)H(298)([Ag(S(8))(2)](+), g)=856 kJ mol(-1) and Delta(f)H(298)([AgS(8)](+), g)=902 kJ mol(-1). It is shown that the [AgS(8)](+) moiety in 2 and the [AgS(8)](2) (+) cations in 3 and 4 are the best approximation of these ions, which were earlier observed by MS methods. Both cations reside in shallow potential-energy wells where larger structural changes only lead to small increases in the overall energy. It is shown that the covalent Agbond;S bonding contributions in both cations may be described by two components: i) the interaction of the spherical empty Ag 5s(0) acceptor orbital with the filled S 3p(2) lone-pair donor orbitals and ii) the interaction of the empty Ag 5p(0) acceptor orbitals with the filled S 3p(2) lone-pair donor orbitals. This latter contribution is responsible for the observed low symmetry of the centrosymmetric Ag(eta(4)-S(8))(2) (+) cation. The positive charge transferred from the Ag(+) ion in 1-4 to the coordinated sulfur atoms is delocalized over all the atoms in the S(8) ring by multiple 3p(2)-->3sigma* interactions that result in a small long-short-long-short Sbond;S bond-length alternation starting from S1 with the shortest Agbond;S length. The driving force for all these weak bonding interactions is positive charge delocalization from the formally fully localized charge of the Ag(+) ion.     

Electrolyte-dependent formation of solid electrolyte interphase and ion intercalation revealed by in situ surface characterizations

The formation of solid electrolyte interphase(SEI) and ion intercalation are two key processes in rechargeable batteries, which need to be explored under dynamic operating conditions. In this work, both planar and sandwich model lithium batteries consisting of Li metal | ionic liquid electrolyte | graphite electrode have been constructed and investigated by a series of in situ surface analysis platforms including atomic force microscopy, Raman and X-ray photoelectron spectroscopy. It is found th...     

The Approaching Revolution in X-Ray Microanalysis: The Microcalorimeter Energy Dispersive Spectrometer

A high-resolution energy-dispersive X-ray spectrometer (EDS) based on cryogenic microcalorimeter X-ray detectors has been developed for use in X-ray microanalysis. With an energy resolution of 3 eV at 1.5 keV, count rate of 500 s^–1, and an effective collection area of 5 mm² (using polycapillary X-ray optics), the microcalorimeter EDS combines many of the favorable qualities of commercially-available wavelength dispersive spectrometers (WDS) and semiconductor EDS. After describing the spectrometer system, we present several applications of microcalorimeter EDS to important microanalysis problems.     

Formulation design, preparation and physicochemical characterizations of solid lipid nanoparticles containing a hydrophobic drug: effects of process variables

This study aimed to prepare solid lipid nanoparticles (SLNs) of a hydrophobic drug, tretinoin, by emulsification-ultrasonication method. Solubility of tretinoin in the solid lipids was examined. Effects of process variables were investigated on particle size, polydispersity index (PI), zeta potential (ZP), drug encapsulation efficiency (EE), and drug loading (L) of the SLNs. Shape and surface morphology of the SLNs were investigated by cryogenic field emission scanning electron microscopy (cryo-FESEM). Complete encapsulation of drug in the nanoparticles was checked by cross-polarized light microscopy and differential scanning calorimetry (DSC). Crystallinity of the formulation was analyzed by DSC and powder X-ray diffraction (PXRD). In addition, drug release and stability studies were also performed. The results indicated that 10mg tretinoin was soluble in 0.45±0.07 g Precirol? ATO5 and 0.36±0.06 g Compritol? 888ATO, respectively. Process variables exhibited significant influence in producing SLNs. SLNs with <120 nm size, <0.2 PI, >I30I mV ZP, >75% EE, and ～0.8% L can be produced following the appropriate formulation conditions. Cryo-FESEM study showed spherical particles with smooth surface. Cross-polarized light microscopy study revealed that drug crystals in the external aqueous phase were absent when the SLNs were prepared at ≤0.05% drug concentration. DSC and PXRD studies indicated complete drug encapsulation within the nanoparticle matrix as amorphous form. The drug release study demonstrated sustained/prolonged drug release from the SLNs. Furthermore, tretinoin-loaded SLNs were stable for 3 months at 4°C. Hence, the developed SLNs can be used as drug carrier for sustained/prolonged drug release and/or to improve oral absorption/bioavailability.     

Detection of negative ions in glow discharge mass spectrometry for analysis of solid specimens

A new method is presented for elemental and molecular analysis of halogen-containing samples by glow discharge time-of-flight mass spectrometry, consisting of detection of negative ions from a pulsed RF glow discharge in argon. Analyte signals are mainly extracted from the afterglow regime of the discharge, where the cross section for electron attachment increases. The formation of negative ions from sputtering of metals and metal oxides is compared with that for positive ions. It is shown that the negative ion signals of F^? and TaO₂F^? are enhanced relative to positive ion signals and can be used to study the distribution of a tantalum fluoride layer within the anodized tantala layer. Further, comparison is made with data obtained using glow-discharge optical emission spectroscopy, where elemental fluorine can only be detected using a neon plasma. The ionization mechanisms responsible for the formation of negative ions in glow discharge time-of-flight mass spectrometry are briefly discussed.     

Study of nanocrystalline BiMnO3-PbTiO3: synthesis, structural elucidation, and magnetic characterization of the whole solid solution

In the last ten years, the study and the search for new multiferroic materials have been a major challenge due to their potential applications in electronic technology. In this way, bismuth-containing perovskites (BiMO(3)), and particularly those in which the metal?M position is occupied by a magnetically active cation, have been extensively investigated as possible multiferroic materials. From the point of view of synthesis, only a few of the possible bismuth-containing perovskites can be prepared by conventional methods but at high pressures. Herein, the preparation of one of these potential multiferroic systems, the solid solution xBiMnO(3)-(1-x)PbTiO(3) by mechanosynthesis is reported. Note that this synthetic method allows the oxides with high x values, and more particularly the BiMnO(3) phase, to be obtained as nanocrystalline phases, in a single step and at room temperature without the application of external pressure. These results confirm that, in the case of Bi perovskites, mechanosynthesis is a good alternative to high-pressure synthesis. These materials have been studied from the point of view of their structural characteristics by precession electron diffraction and magnetic property measurements.     

Isolating the whole complex of target proteins of FK506 using affinity resins from novel solid phases

The development of novel solid phases enabled us to create affinity resins that could be used to isolate the whole complex of target proteins responsible for the immunosuppressive effects of FK506 from rat brain lysate, whereas the affinity resins from commercially available matrices could not achieve this isolation. The results illustrate the enhanced effectiveness of the affinity resin made from this novel material at identifying the target protein of the bioactive compound compared to resins made from the well-known materials Affigel or Toyopearl. This effectiveness arises because the novel material is hydrophilic enough to reduce nonspecific binding proteins and because it has a higher density of ligands that capture the nonubiquitous target protein. Electronic Supplementary Material Supplementary material is available for this article at     

Approaching the proteoglycome: molecular interactions of proteoglycans and their functional output

[Image: see text] Through their diverse core protein modules and glycan/glycosaminoglycan moieties, proteoglycans may engage in numerous cellular and molecular interactions which are dispensable during embryogenesis, are essential for the maintenance of a healthy state and are prone to modulation in pathological conditions. Proteoglycan interactions may involve binding to other structural components of the ECM, to cell surface receptors, to membrane-associated components, and to soluble signaling molecules, which through this interaction may become entrapped in the ECM or sequestered at the cell surface. Understanding of these multiple interplays is therefore of paramount importance and requires a detailed mapping through what we define as the proteoglycome.     

The physical and NMR characterizations of allyl‐ and crotylcelluloses

Tri‐O‐allylcellulose (degree of polymerization, DP ∼112) was prepared in ∼91% yield, and tri‐O‐crotylcellulose (DP ∼138) was prepared in ∼56% yield from microcrystalline cellulose (DP ∼172, and polydispersity index, PDI ∼1.95) using modified literature methods. Number‐average molecular weight (M_n = 31,600), weight‐average molecular weight (M_w = 191,800), and PDI = 6.07 data suggested that tri‐O‐allylcellulose may be crosslinking in air to generate branched chains. The polymer was stabilized with 100 ppm butylated hydroxy toluene (BHT). The material without BHT experienced glass transition (T_g, differential‐scanning calorimetry, DSC) between −2 and +3 °C, crosslinked beyond 100 °C, and degraded at 298.6 °C (by thermogravimetric analysis, TGA). M_n (45,100), M_w (118,200), PDI (2.62), and thermal data (T_g − 5 to +3 °C, melting point 185.8 °C, recrystallization 168.9 °C, and degradation 343.6 °C) on tri‐O‐crotylcellulose suggested that the polymer was formed with about the same polydispersity as the starting material and is heat stable. While allylcellulose generated continuous flexible yellow films by solution casting, crotylcellulose precipitated from solution as brittle white flakes. Dynamic mechanical analysis (DMA) data on allylcellulose films (T_g − 29.1 °C, Young's modulus 5.81 × 10⁸ Pa) suggest that the material is tough and flexible at room temperature. All ¹H and ¹³C resonances in the NMR spectra were identified and assigned using the following methods: Double‐quantum filter correlation spectroscopy (DQF COSY) was used to assign the network of seven protons in the anhydroglucose portion of the repeat unit. The proton assignments were verified and confirmed by total correlation spectroscopy (TOCSY). A combination of heteronuclear single‐quantum coherence (HSQC) and ¹³C spectroscopies were used to identify all bonded carbon–hydrogen pairs in the anhydroglucose portion of the repeat unit, and assign the carbon nuclei chemical shift values. Heteronuclear multiple bond correlation (HMBC) spectroscopy was used to connect the resonances of methines and methylenes at positions 2, 3, and 6 to the methylene resonances of the allyl ethers. TOCSY was used again to identify the fifteen ¹H resonances in the three pendant allyl groups. Finally, a combination of HSQC, HMBC, and ¹³C spectroscopies were used to identify each carbon in the allyl pendants at 2, 3, and 6. Because of line broadening and signal overlap, we were unable to identify the conformational arrangement about the C5 and C6 bond in tri‐O‐allyl‐ and tri‐O‐crotylcelluloses. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 1889–1902, 2000     

Approaching the full set of energy levels of water

We report here the measurements of rovibrational levels in the electronic ground state of water molecule at the previously inaccessible energies above 26,000 cm(-1). The use of laser double-resonance overtone excitation extends this limit to 34,200 cm(-1), which corresponds to 83% of the water dissociation energy. We use experimental data to generate a semiempirical potential energy surface that now allows prediction of water levels with sub-cm(-1) accuracy at any energy up to the new limit.     

The teaching of problem solving: Environmental analysis

Summary An attempt is made to describe the present field of activities of analytical chemistry using environmental analysis as an example. Some conclusions concerning education in analytical chemistry at the universities are presented.

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Ausbildung in der Lösung von Problemen: Umwelt-Analytik

Zusammenfassung Am Beispiel Umwelt-Analytik wird versucht, das heutige Tätigkeitsfeld der Analytischen Chemie zu beschreiben und daraus einige Folgerungen für die Ausbildung in Analytischer Chemie an den Hochschulen abzuleiten.

     

An analytical method for the determination of perfluorinated compounds in whole blood using acetonitrile and solid phase extraction methods

A method for the analysis of perfluorinated compounds (perfluoroalkyl sulfonates: C4, C6, C8, C10; perfluoroalkyl sulfinates: C6, C8, C10; perfluorooctanesulfonamide, N-ethyl perfluorooctanesulfonamide, N-ethyl perfluorooctanesulfonamidoacetate, perfluorocarboxylates: C4–C14; fluorotelomer carboxylate (7:3, 8:2) in whole blood using acetonitrile and OASIS WAX^® solid phase extraction (SPE) cartridge was developed. Separation of target compounds in two HPLC columns (ion exchange JJ50-2D and C18 Betasil columns) was examined. Matrix recoveries of the developed methods ranged from 70% to 120%. Separation of possible inferences such as taurodeoxycholic acid (TDC) was accomplished using an ion exchange JJ50-2D column, and this separation was validated using whole blood of different animals.     

Approaching the uniaxiality of magnetic anisotropy in single-molecule magnets

Single-molecule magnets(SMMs), which can exhibit slow magnetization relaxation and bulk-magnet-like hysteresis of purely molecular origin, are promising candidates for high-density information storage, molecular spintronics, and quantum computing.To realize their applications, it is crucial to improve the blocking temperature(T_B) and the effective relaxation barrier(U_eff).Three decades of multidisciplinary research have yielded distinct SMMs with a state-of-the-art U_ef...     

走近放射性药物化学——学习和认识正电子核素标记的放射性药物

正电子核素标记的放射性药物是正电子发射计算机断层显像(positron emission computed tomography,PET)发挥功能的关键因素,其开发和临床转化是PET诊断技术发展的核心技术之一。简要介绍PET显像原理及其安全性、PET与其他医学影像技术的区别,阐述放射性药物合成、标记及其临床应用等相关内容,旨在普及放射性药物及其PET显像技术的相关知识。可供教师选用于教学参考,拓展学生化学应用视野,提升学生科学素养。