Synthese der geschützten insulin-teilsequenz b 1–8

The synthesis of the octapeptide derivative Z-Phe-Val-Asn-Gln-His(Trt)-Leu-Cys(SEt)-Gly-OH with the terminal sequence 1-8 of the insulin B chain using the subunits Z-Phe-Val-OH, Boc-Asn-Gln-His(Trt)-OMe and Boc-Leu-Cys(SEt)-Gly-OH is reported.     

Direct identification of early synthetic dyes: FT-Raman study of the illustrated broadside prints of José Gaudalupe Posada (1852–1913)

Fourier Transform (FT)-Raman spectroscopy was used for the non-invasive, direct identification of colorants used to dye historical printed papers, overcoming obstacles such as low concentration of the dye, faded colors and fluorescence interference of the aged paper substrate.     

Synthesis and structures of Pb3O2(CH3COO)2·0.5H2O and Pb2O(HCOO)2: two corrosion products revisited

Reactions of carboxylic acids with lead play an important role in the atmospheric corrosion of lead and lead-tin alloys. This is of particular concern for the preservation of lead-based cultural objects, including historic lead-tin alloy organ pipes. Two initial corrosion products, Pb(3)O(2)(CH(3)COO)(2)·0.5H(2)O (1) and Pb(2)O(HCOO)(2) (2), had been identified through powder diffraction fingerprints in the Powder Diffraction File, but their structures had never been determined. We have crystallized both compounds using hydrothermal solution conditions, and structures were determined using laboratory and synchrotron single-crystal X-ray diffraction data. Compound 1 crystallizes in P1, and 2 in Cccm. These compounds may be viewed as inorganic-organic networks containing single and double chains of edge-sharing Pb(4)O tetrahedra and have structural similarities to inorganic basic lead compounds. Bond valence sum analysis has been applied to the hemidirected lead coordination environments in each compound. Atmospheric exposure experiments contribute to understanding of the potential for conversion of these short-term corrosion products to hydrocerussite, Pb(3)(CO(3))(2)(OH)(2), previously identified as a long-term corrosion product on lead-rich objects. Each compound was also characterized by elemental analysis, thermogravimetric analysis and differential scanning calorimetry (TGA-DSC), and Raman spectroscopy.     

Synthese eines dekapeptid-derivates mit der sequenz b 21–30 des rinderinsulins

The synthesis of the benzyltype protected bovine insulin fragment B 21–30 Boc-Glu(OBzl)-Arg(H+)-Gly-Phe-Phe-Tyr(Bzl)-Thr(Bzl)-Pro-Lys(Z)-Ala-OBzl following the route 3 + 3 + 4 is described. In addition, the solid phase technique is applied to the synthesis of the corresponding protected sequence B 24–30.     

Syntheses of silatranyl- and germatranyluridines

[reaction: see text] Silatranyluridine 1 and germatranyluridine 2 have been prepared in five steps from oxazolinouridine 3 in 27 and 29% yields, respectively. These compounds are novel transition-state analogues (TSAs) for RNA hydrolysis and offer a number of advantages over traditional vanadium- or rhenium-based TSAs. Germatrane 2 is completely stable in D(2)O at room temperature, and the half-life of silatrane 1 in D(2)O was found to be >7 days by (1)H NMR spectroscopy.     

The Role of Osmotic Pressure and Tension-Compression Nonlinearity in the Frictional Response of Articular Cartilage

Articular cartilage is the bearing material of diarthrodial joints such as the knee, hip, or shoulder. Some studies of cartilage lubrication have hypothesized that pressurization of its interstitial fluid may contribute predominantly to reducing the friction coefficient at the contact interface of articular layers. This study introduces a formulation for the dependence of the frictional response of articular cartilage on interstitial fluid pressurization, which accounts for the osmotic pressure in cartilage as well as the tissue's tension-compression nonlinearity, and is based on the theory of mixtures for soft hydrated charged tissues. Theoretical predictions of this model are obtained for the configuration of unconfined compression creep. It is observed from theory that increasing the salt concentration of the tissue's bathing solution reduces the minimum friction coefficient that can be achieved, relative to its equilibrium value; the model also predicts that increasing the applied load can similarly reduce the minimum friction coefficient. Physical interpretations of these phenomena are provided by the model. Experimental results are presented which support these theoretical findings and produce time-dependent responses in good agreement with model predictions. Furthermore, it is observed that the equilibrium friction coefficient does not remain constant under various loads or salt concentrations, and correlation analyses suggest that the equilibrium value depends in part on the compressive strain in the tissue.     

Zur Reaktion von Imidodiphosphoryltetrachlorid mit Phosphorpentachlorid

Reaction of Imidodiphosphoryl Tetrachloride with Phosphorus Pentachloride Imidodiphosphoryl tetrachloride quantitatively reacts with PCl₅ to form, HCl, POCl₃, and Cl₃P?N? POCl₂. The mechanism of the reaction is discussed. Using ³²P-labeled PCl₅ was proved that the attack of the PCl₅ to imidodiphosphoryl tetrachloride does occur about an oxygen atom.     

Underwater auditory localization by a swimming harbor seal (Phoca vitulina)

The underwater sound localization acuity of a swimming harbor seal (Phoca vitulina) was measured in the horizontal plane at 13 different positions. The stimulus was either a double sound (two 6-kHz pure tones lasting 0.5 s separated by an interval of 0.2 s) or a single continuous sound of 1.2 s. Testing was conducted in a 10-m-diam underwater half circle arena with hidden loudspeakers installed at the exterior perimeter. The animal was trained to swim along the diameter of the half circle and to change its course towards the sound source as soon as the signal was given. The seal indicated the sound source by touching its assumed position at the board of the half circle. The deviation of the seals choice from the actual sound source was measured by means of video analysis. In trials with the double sound the seal localized the sound sources with a mean deviation of 2.8 degrees and in trials with the single sound with a mean deviation of 4.5 degrees. In a second experiment minimum audible angles of the stationary animal were found to be 9.8 degrees in front and 9.7 degrees in the back of the seal's head.