Non-symmetrical line broadening effects using short-pulse QCL spectrometers as determined with sub-nanosecond time-resolution

Quantum cascade lasers (QCLs) have attracted considerable interest as an alternative tuneable narrow bandwidth light source in the mid-infrared spectral range for chemical sensing. Pulsed QCL spectrometers are often used with short laser pulses and a bias current ramp similar to diode laser spectroscopy. Artefacts in the recorded spectra such as disturbed line shapes or underestimated absorption coefficients have been reported. A detailed time-resolved high-bandwidth analysis of individual pulses during a laser sweep has been performed. Quantitative results for CH₄ absorption features around 1347 cm⁻¹ (7.42 μm) fell short of the expected values for reasonable operating conditions of the QCL. The origin of the artefacts using short pulses was identified to be partly of the same nature as in the case of long laser pulses. A complex combination with the tuning principle was found, leading to an apparently increased instrumental broadening (effective line width) and underestimated concentrations at low-pressure conditions.     

Rational Design of a Humanized Glucagon‐Like Peptide‐1 Receptor Agonist Antibody

Bovine antibody BLV1H12 possesses a unique “stalk–knob” architecture in its ultralong heavy chain CDR3, allowing substitutions of the “knob” domain with protein agonists to generate functional antibody chimeras. We have generated a humanized glucagon‐like peptide‐1 (GLP‐1) receptor agonist antibody by first introducing a coiled‐coil “stalk” into CDR3H of the antibody herceptin. Exendin‐4 (Ex‐4), a GLP‐1 receptor agonist, was then fused to the engineered stalk with flexible linkers, and a Factor Xa cleavage site was inserted immediately in front of Ex‐4 to allow release of the N‐terminus of the fused peptide. The resulting clipped herceptin–Ex‐4 fusion protein is more potent in vitro in activating GLP‐1 receptors than the Ex‐4 peptide. The clipped herceptin–Ex‐4 has an extended plasma half‐life of approximately four days and sustained control of blood glucose levels for more than a week in mice. This work provides a novel approach to the development of human or humanized agonist antibodies as therapeutics.     

Nachbargruppeneffekte bei der Elektronenstoß-Induzierten Fragmentierung von Acetylierten 2.2′-Diamino-Diphenylmethanen

The mono- and bis-acetylated 2,2′-diamino-diphenylmethanes (I to V) exhibit strong elimination of water from the molecular ions upon electron-impact. The corresponding fragmentation processes were investigated by means of deuterium labelling.     

Assembly modulates dissociation: electrokinetic experiments reveal peculiarities of the charge formation at monolayer films

Self-assembled monomolecular films of alkanethiols chemisorbed on gold were used as a two-dimensional model system to study the effects of spatial confinement of surface functional groups on their acid-base behaviour; reduction of the surface charge density by mixed assemblies revealed an increase of the acidity of carboxy groups; surfaces with low amounts of charged groups show the interplay of dissociation of functional groups and preferential adsorption of ions in terms of surface charge formation.