Ba8Cu16P30 – eine neue ternäre Variante des Clathrat I-Strukturtyps

Ba₈Cu₁₆P₃₀ – a New Ternary Variant of the Clathrate I Type Structure Ba₈Cu₁₆P₃₀ (a = 14.117(1) Å, b = 10.093(1) Å, c = 28.022(2) Å) was prepared by heating a mixture of the elements (800°C; excess of Ba and P; removal of the by-products by acetic acid/H₂O₂). The compound crystallizes orthorhombically (Pbcn; Z = 4) in a new superstructure of the cubic clathrate I type structure with an ordered distribution of the atoms. The structure is characterized by a three-dimensional framework of CuP₄ tetrahedra with cavities in the form of pentagonal dodecahedra and tetrakaidecahedra, which are occupied by the Ba atoms. The compound shows semiconduction, therefore the composition should be Ba₈Cu_15.5P_30.5.     

Preparation and characterization of individual peptide-wrapped single-walled carbon nanotubes

Two challenges for effectively exploiting the remarkable properties of single-walled carbon nanotubes (SWNTs) are the isolation of intact individual nanotubes from the raw material and the assembly of these isolated SWNTs into useful structures. In this study, we present atomic force microscopy (AFM) evidence that we can isolate individual peptide-wrapped SWNTs, possibly connected end-to-end into long fibrillar structures, using an amphiphilic alpha-helical peptide, termed nano-1. Transmission electron microscopy (TEM) and well-resolved absorption spectral features further corroborate nano-1's ability to debundle SWNTs in aqueous solution. Peptide-assisted assembly of SWNT structures, specifically in the form of Y-, X-, and intraloop junctions, was observed in the AFM and TEM images.     

In situ tissue pathology from spatially encoded mass spectrometry classifiers visualized in real time through augmented reality

Integration between a hand-held mass spectrometry desorption probe based on picosecond infrared laser technology (PIRL-MS) and an optical surgical tracking system demonstrates in situ tissue pathology from point-sampled mass spectrometry data. Spatially encoded pathology classifications are displayed at the site of laser sampling as color-coded pixels in an augmented reality video feed of the surgical field of view. This is enabled by two-way communication between surgical navigation and mass spectrometry data analysis platforms through a custom-built interface. Performance of the system was evaluated using murine models of human cancers sampled in situ in the presence of body fluids with a technical pixel error of 1.0 ± 0.2 mm, suggesting a 84% or 92% (excluding one outlier) cancer type classification rate across different molecular models that distinguish cell-lines of each class of breast, brain, head and neck murine models. Further, through end-point immunohistochemical staining for DNA damage, cell death and neuronal viability, spatially encoded PIRL-MS sampling is shown to produce classifiable mass spectral data from living murine brain tissue, with levels of neuronal damage that are comparable to those induced by a surgical scalpel. This highlights the potential of spatially encoded PIRL-MS analysis for in vivo use during neurosurgical applications of cancer type determination or point-sampling in vivo tissue during tumor bed examination to assess cancer removal. The interface developed herein for the analysis and the display of spatially encoded PIRL-MS data can be adapted to other hand-held mass spectrometry analysis probes currently available.

Integration between a hand-held mass spectrometry desorption probe based on picosecond infrared laser technology (PIRL-MS) and an optical surgical tracking system demonstrates in situ tissue pathology from point-sampled mass spectrometry data.     

Strukturen aus AIB2− und BaAl4−analogen Einheiten. I Die Verbindungen Sr4Pd5P5 und Sr2Pd3P3

Structures with AIB₂? and BaAl₄?type Units. I The Compounds Sr₄Pd₅P₅ and Sr₂Pd₃P₃ Sr₄Pd₅P₅ (Cmcm, a = 4.177(1) Å, b = 31.377(5) Å, c = 8.581(2) Å, Z = 4) und Sr₂ Pd₃P₃(Pmmm, a = 4.199(1) Å, b = 4.212(1) Å, c = 34.227(4) Å, Z = 4) have been prepared by heating the elements. Both structures contain exclusively units characteristic for the AIB_2? and BaAl₄?type. The ratio between isolated P-atoms and P₂?pairs is interpreted with an ionic splitting of the formulas.     

ACu9X4 ‐ Neue Verbindungen mit der CeNi8, 5Si4, 5‐Struktur (A: Sr,Ba; X: Si,Ge)

ACu₉X₄ ‐ New Compounds with CeNi_{8, 5}Si_{4, 5} Structure (A: Sr, Ba; X: Si, Ge) The new compounds SrCu₉Si₄ (a = 8.146(1), c = 11.629(2)Å), BaCu₉Si₄ (a = 8.198(2), c = 11.735(2)Å), SrCu₉Ge₄ (a = 8.273(2), c = 11.909(5)Å), and BaCu₉Ge₄ (a = 8.338(4), c = 12.011(7)Å) are formed by reaction of the elements at 1000° ‐ 1100 °C. They are isotypic (I4/mcm, Z = 4) and crystallize in an ordered variant of the cubic NaZn₁₃ type structure, also built up by the binary phase BaCu₁₃. In the ternary compounds the positions of Cu2 are orderly occupied by copper and silicon and germanium, respectively. This results in a lowering of symmetry and a distortion of the polyhedra. The metallic conductivity of the compounds was confirmed by measurements on BaCu₉Si₄.     

Stripping Analysis of Trace Metals at a Flow-Through Reticulated Vitreous Carbon Electrode after the Preconcentration by Supported Liquid Membrane Technique

Abstract

The performance of a flow-through mercury coated reticulated vitreous carbon (RVC) electrode in the potentiometric stripping analysis (PSA) of trace metals has been examined. A wall-jet glassy carbon cell was used for the comparative experiments. Experimental parameters influencing the stripping signals have been optimised in order to use the stripping analysis after the preconcentration and matrix isolation by supported liquid membrane (SLM) technique. The SLM with di-2-ethylhexyl-phosphoric acid (DEHPA) as the extractant in the membrane liquid for proton driven transport of trace metals across the membrane has been chosen. Results presented for lead determination in river water demonstrate the analytical advantages of coupled technique SLM-PSA.     

Effect of conformational parameters on physical properties of polymers containing pendant phenoxyphthalonitrile substituents

Heteroaromatic polymers are considered to be high performance organic materials due to their unique and highly attractive properties, including outstanding thermal and mechanical resistance, that arise from their aromatic structure and strong interactions between macromolecular chains. Modification or designing new molecular architectures with tailored physico-chemical characteristics allows expanding the applications of these materials in various advanced technologies. Herein, a series of polymers containing bulky phenoxyphthalonitrile pendant units was synthesized and their physical properties were studied and correlated with their conformational parameters, as well as free and van der Waals volumes. For comparison, the related polymers without lateral moieties were also investigated to highlight the effect of bulky substituent on the polymer rigidity. Thus, it is shown that conformational rigidity determines the packing of macromolecules in solid state, and, therefore, the free volume, glass transition, and decomposition temperatures. The values found experimentally for T _g correlate well with those obtained using the conformational rigidity parameters. The dependence of T _g of these polymers on Kuhn segment is described by linear equations, with very good factors of convergence. The correlations established by Monte Carlo method allow obtaining the T _g values for related polymers where the experimental measurement of this parameter is difficult.     

Effect of Protic Ionic Liquid and Surfactant Structure on Partitioning of Polyoxyethylene Non‐ionic Surfactants

The partitioning constants and Gibbs free energies of transfer of poly(oxyethylene) n‐alkyl ethers between dodecane and the protic ionic liquids (ILs) ethylammonium nitrate (EAN) and propylammonium nitrate (PAN) are determined. EAN and PAN have a sponge‐like nanostructure that consists of interpenetrating charged and apolar domains. This study reveals that the ILs solvate the hydrophobic and hydrophilic parts of the amphiphiles differently. The ethoxy groups are dissolved in the polar region of both ILs by means of hydrogen bonds. The environment is remarkably water‐like and, as in water, the solubility of the ethoxy groups in EAN decreases on warming, which underscores the critical role of the IL hydrogen‐bond network for solubility. In contrast, amphiphile alkyl chains are not preferentially solvated by the charged or uncharged regions of the ILs. Rather, they experience an average IL composition and, as a result, partitioning from dodecane into the IL increases as the cation alkyl chain is lengthened from ethyl to propyl, because the IL apolar volume fraction increases. Together, these results show that surfactant dissolution in ILs is related to structural compatibility between the head or tail group and the IL nanostructure. Thus, these partitioning studies reveal parameters for the effective molecular design of surfactants in ILs.