Trace elements in Variegated Bolete (Suillus variegatus) fungi

Metallic elements such as Ag, Al, Ba, Ca, Cd, Co, Cr, Cu, Fe, K, Mg, Mn, Na, Ni, Pb, Rb, Sr, and Zn were determined using ICP-OES in a representative set of fifteen fruiting bodies of the edible fungus Suillus variegatus. Fruiting bodies were collected from unpolluted areas near the village of Lubichowo of the Bory Tucholskie forest complex in northern Poland in 2007?C2008. The caps were richer in Ag, Al, Cd, Cr, Cu, Fe, K,Mg, Ni, Rb, and Zn, and the stipes in Ba, Ca, Mn, Na, Pb, and Sr. Cobalt concentration in the caps and stipes was similar. In the caps, the content of the elements decreased in the order (mg per kg of dry weight): K 29000 ± 3700, Fe 1600 ± 80, Mg 990 ± 110, Rb 320 ± 86, Zn 90 ± 19, Ca 75 ± 34, Al 68 ± 32, Na 40 ± 18, Cu 19 ± 7, Mn 13 ± 7, Cd 1.0 ± 0.5, Ni 0.64 ± 0.32, Ag 0.40 ± 0.20, Cr 0.33 ± 0.06, Pb 0.20 ± 0.17, Ba 0.19 ± 0.11, Sr 0.15 ± 0.09, and Co 0.070 ± 0.050. Apparently, S. variegatus collected from background areas are relatively low in Pb and Cd and so are suitable for human consumption.     

Chirality measures of α-amino acids

To measure molecular chirality, the molecule is treated as a finite set of points in the Euclidean R(3) space supplemented by k properties, p(1)((i)), p(2)((i)), ..., p(k)((i)) assigned to the ith atom, which constitute a point in the Property P(k) space. Chirality measures are described as the distance between a molecule and its mirror image minimized over all its arbitrary orientation-preserving isometries in the R(3) × P(k) Cartesian product space. Following this formalism, different chirality measures can be estimated by taking into consideration different sets of atomic properties. Here, for α-amino acid zwitterionic structures taken from the Cambridge Structural Database and for all 1684 neutral conformers of 19 biogenic α-amino acid molecules, except glycine and cystine, found at the B3LYP/6-31G** level, chirality measures have been calculated by a CHIMEA program written in this project. It is demonstrated that there is a significant correlation between the measures determined for the α-amino acid zwitterions in crystals and the neutral forms in the gas phase. Performance of the studied chirality measures with changes of the basis set and computation method was also checked. An exemplary quantitative structure–activity relationship (QSAR) application of the chirality measures was presented by an introductory model for the benchmark Cramer data set of steroidal ligands of the sex-hormone binding globulin.     

Sorptive properties of aluminium ions containing mesoporous silica towards <Emphasis Type="SmallCaps">l</Emphasis>-histidine

The applicability of aluminium-containing mesoporous materials as carriers for l-histidine has been evaluated for the first time. The modified mesoporous silica such as SBA-15 and SBA-16 were synthesised by hydrothermal method and characterised by low-temperature nitrogen sorption, transmission and scanning microscopy, X-ray and laser diffraction methods. The results of these studies confirmed the ordered mesoporous structures of all materials obtained. The modification of mesoporous materials with aluminium ions changed the textural parameters and particle size distribution relative to those in the pristine material. Aluminium-modified SBA-15 exhibited higher release rate of amino acid than the pure material. The opposite phenomenon was observed when l-His was released from pristine and modified SBA-16 materials. The kinetics of amino acid release from all mesoporous materials followed the Korsmeyer–Peppas model. The results proved that the structural parameters of mesoporous materials and the percentage content of aluminium strongly influenced the release rate of l-His.     

Functional molecular wires

The properties of self-assembled molecules may be tuned by sequentially coupling components on a gold surface, the molecular electronics toolbox of chemically reactive building blocks yielding molecular wires with diode-like current-voltage (I-V) characteristics. The bias for rectification in each case is dependent upon the sequence of electron-donating and electron-accepting moieties and similar behaviour has been achieved for four different contacting techniques.     

Lu2O3:Tb,Hf storage phosphor

Lu₂O₃:Tb,Hf ceramics containing 0.1% of Tb and 0–1.5% of Hf were prepared in reducing atmosphere at 1700 °C and their thermoluminescence properties were systematically studied. For comparison Tb,Ca co-doped specimen was also fabricated and investigated. The Tb,Hf ceramics shows basically a single TL band located around 180 °C as found with heating rate of 15 °C/min. Ceramics singly doped with Tb show complex TL glow curves indicating the presence of traps of very different depths. On the other hand Tb,Ca co-doping is beneficial for the development of shallow traps with the main TL band around 70 °C. Hence, the aliovalent impurities, Ca²⁺ and Hf⁴⁺, strongly influenced the traps structure in Lu₂O₃:Tb ceramics, each of them in its own specific way. Isothermal decay of Lu₂O₃:Tb,Hf at 185 °C was recorded and its shape suggest that multiple hole trapping occurs in the Lu₂O₃:Tb,Hf ceramics. Due to the different traps depths the Lu₂O₃:Tb,Hf ceramics possess properties typical for storage phosphors, while Lu₂O₃:Tb,Ca is a persistent luminescent material rather.     

Crystallography Aided by Atomic Core-Level Binding Energies: Proton Transfer versus Hydrogen Bonding in Organic Crystal Structures

Ionic bond or hydrogen bridge? Br?nsted proton transfer to nitrogen acceptors in organic crystals causes strong N1s core-level binding energy shifts. A study of 15 organic cocrystal and salt systems shows that standard X-ray photoelectron spectroscopy (XPS) can be used as a complementary method to X-ray crystallography for distinguishing proton transfer from H-bonding in organic condensed matter.     

Label‐Free Nanoimaging of Neuromelanin in the Brain by Soft X‐ray Spectromicroscopy

A hallmark of Parkinson's disease is the death of neuromelanin‐pigmented neurons, but the role of neuromelanin is unclear. The in situ characterization of neuromelanin remains dependent on detectable pigmentation, rather than direct quantification of neuromelanin. We show that direct, label‐free nanoscale visualization of neuromelanin and associated metal ions in human brain tissue can be achieved using synchrotron scanning transmission x‐ray microscopy (STXM), through a characteristic feature in the neuromelanin x‐ray absorption spectrum at 287.4 eV that is also present in iron‐free and iron‐laden synthetic neuromelanin. This is confirmed in consecutive brain sections by correlating STXM neuromelanin imaging with silver nitrate‐stained neuromelanin. Analysis suggests that the 1s–σ* (C?S) transition in benzothiazine groups accounts for this feature. This method illustrates the wider potential of STXM as a label‐free spectromicroscopy technique applicable to both organic and inorganic materials.     

Synthesis,Characterization, and Crystal Structures of Cu,Ag, and Pd Dinitramide Salts

The literature known, but not fully characterized, silver dinitramide transfer reagents AgN(NO₂)₂ ( 1 ), [Ag(NCCH₃)][N(NO₂)₂] ( 2 ), and [Ag(py)₂][N(NO₂)₂] ( 3 ) have been investigated by ¹⁰⁹Ag, ¹⁴N NMR and vibrational spectroscopy (IR, Raman). In addition, the poorly understood [Cu(NH₃)₄][N(NO₂)₂)]₂ ( 4 ) and [Pd(NH₃)₄][N(NO₂)₂]₂, ( 5 ) have also been prepared and characterized by ¹⁴N NMR and vibrational spectroscopy (IR, Raman). The structures of 2 — 5 have also been determined by X‐ray diffraction.     

Apparent molar volumes and compressibilities of tetrabutyl-ammonium bromide in organic solvents

The densities of tetra-n-butylammonium bromide in 1-propanol, 1-butanol, acetone at (288.15, 293.15, 298.15, 303.15, 308.15, 313.15, and 323.15) K and sound velocities at 298.15 K have been measured. From these data apparent molar volumes V_Φ at (288.15, 293.15, 298.15, 303.15, 308.15, 313.15, and 323.15) K and the apparent molar isenotropic compressibility K_S,Φ, at T = 298.15 K of tetrabutylammonium bromide in nonaqueous solvents have been determined. The apparent molar volumes and the apparent molar isenotropic compressibilities were fitted to the Redlich, Rosenfeld, and Mayer equation as well as to the Pitzer equation yielding infinite dilution data, which were compared to the similar quantities for tetrabutylphosphonium bromide. Moreover, the acoustical parameters such as intermolecular free length (L_f), relative association (R_A), Rao’s molar sound function (R_m), and salvation number (S_n) were calculated using the experimental data of density and sound velocity at T = 298.15 K for ammonium and phosphonium bromides. The obtained data suggest the penetration of the acetone molecule within the intraionic free space of the tetrabutyl-ammonium and phosphonium cations.