Secondary structure of Ac-Alan_n-LysH+^+ polyalanine peptides (nn=5,10,15) in vacuo: Helical or not?

The polyalanine-based peptide series Ac-Ala_n-LysH+ (n=5-20) is a prime example that a secondary structure motif which is well-known from the solution phase (here: helices) can be formed in vacuo. We here revisit this conclusion for n=5,10,15, using density-functional theory (van der Waals corrected generalized gradient approximation), and gas-phase infrared vibrational spectroscopy. For the longer molecules (n=10,15) \alpha-helical models provide good qualitative agreement (theory vs. experiment) already in the harmonic approximation. For n=5, the lowest energy conformer is not a simple helix, but competes closely with \alpha-helical motifs at 300K. Close agreement between infrared spectra from experiment and ab initio molecular dynamics (including anharmonic effects) supports our findings.Comment: 4 pages, 4 figures, Submitted to JPC Letter

Dynamic polarization and relaxation of protons in 1,6-hexanediol and 1,8-octanediol: a feasibility study for a frozen spin polarized target

Results are given of an experiment to test 1,6-hexanediol and 1,8- octanediol for their suitability as materials for polarized proton targets. The samples are doped with 15% Cr/sup V/-glycol complexes. Polarization results are reported at temperatures between 0.4 K and 1.0 K. Relaxation times in different magnetic fields are measured for hexanediol down to 270 mK, for octanediol down to 54 mK. Conclusions are drawn for the parameters of a frozen spin target. (28 refs)

Immunochromatographic Lateral-flow test strip for the rapid detection of added bovine rennet whey in milk and milk powder

An immunochromatographic lateral-flow test dipstick test was developed for the fast detection of bovine rennet whey in liquid milk and milk powder. The test is based on the binding of casein glycomacropeptide (cGMP) by two specific anti-bovine ¿-casein monoclonal antibodies and has a visual detection limit of around 15 ng mL¿1 for cGMP and 1% (v/v) for rennet whey in milk using standards and spiked samples. The dipstick performance was evaluated in a collaborative trial using skim milk powder and raw, pasteurized and UHT milk. The suitability of the dipstick was demonstrated in comparison with gel permeation-high performance liquid chromotography and a colorimetric method, by analysing 60 raw milk samples collected from farms in Brazil. The dipstick results correlated well with the HPLC results and were more reliable than those obtained with the colorimetric method. The dipstick test correctly identified all raw milk samples with a rennet whey content above 4%

Enzymatic synthesis of lignin-based concrete dispersing agents

Lignin is the most abundant aromatic biopolymer, functioning as an integral component of woody materials. In its unmodified form it shows limited water solubility and is relatively unreactive, so biotechnological lignin valorisation for high-performance applications is greatly underexploited. Lignin can be obtained from the pulp and paper industry as a by-product. To expand its application, a new synthesis route to new dispersing agents for use as concrete additives was developed. The route is based on lignin functionalisation by enzymatic transformation. Screening of lignin-modifying systems resulted in functionalised lignin polymers with improved solubility in aqueous systems. Through grafting of sulfanilic acid or p-aminobenzoic acid by fungal laccases, lignin became soluble in water at pHâ¤4 or pHâ¤7, respectively. Products were analysed and evaluated in miniaturised application tests in cement paste and mortar. Their dispersing properties match the performance criteria of commercially available lignosulfonates. The study provides examples of new perspectives for the use of lignin

Revised Supporting Information for Journal Article "Redox-Active Chiroptical Switching in Mono- and Bis-Iron Ethynylcarbo[6]helicenes Studied by Electronic and Vibrational Circular Dichroism and Resonance Raman Optical Activity"

This upload contains the revised parts of the supporting information for the journal article "Redox-Active Chiroptical Switching in Mono- and Bis-Iron Ethynylcarbo[6]helicenes Studied by Electronic and Vibrational Circular Dichroism and Resonance Raman Optical Activity" (Chem. Eur. J., 2018, 24, 15067)