Oxidation Monitoring by Fluorescence Spectroscopy Reveals the Age of Fingermarks

No forensic method exists that can reliably estimate the age of fingermarks found at a crime scene. Information on time passed since fingermark deposition is desired as it can be used to distinguish between crime related and unrelated fingermarks and to support or refute statements made by the fingermark donors. We introduce a non‐contact method that can estimate the age of fingermarks. Fingermarks were approached as protein–lipid mixtures and an age‐estimation model was build based on the expected protein and lipid oxidation reactions. Two measures of oxidation are required from the fingermark to estimate its age: 1) the relative amount of fluorescent oxidation products 2) the rate at which these products are formed. Fluorescence spectroscopy was used to obtain these measures. We tested the method on 44 fingermarks and were able to estimate the age of 55 % of the male fingermarks, up to three weeks old with an uncertainty of 1.9 days.     

Structural similarities among eight benzoylhydrazones

The crystal structures of eight benzoylhydrazones with different substituents have been investigated, namely 1‐benzoyl‐2‐(propan‐2‐ylidene)hydrazone, C₁₀H₁₂N₂O, (I), 1‐benzoyl‐2‐(1‐cyclohexylethylidene)hydrazone, C₁₅H₂₀N₂O, (II), 1‐benzoyl‐2‐[1‐(naphthalen‐2‐yl)ethylidene]hydrazone, C₁₉H₁₆N₂O, (III), 1‐benzoyl‐2‐(1‐cyclohexylbenzylidene)hydrazone, C₂₀H₂₂N₂O, (IV), 1‐benzoyl‐2‐(1‐phenylbenzylidene)hydrazone, C₂₀H₁₆N₂O, (V), 1‐benzoyl‐2‐[1‐(4‐chlorophenyl)benzylidene]hydrazone, C₂₀H₁₅ClN₂O, (VI), 1‐benzoyl‐2‐(4‐hydroxybenzylidene)hydrazone methanol monosolvate, C₁₄H₁₂N₂O₂·CH₃OH, (VII), and 1‐benzoyl‐2‐(1,1‐diphenylpropan‐2‐ylidene)hydrazone, C₂₂H₂₀N₂O, (VIII). The ten molecules in the eight crystal structures [there are two independent molecules in the structures of (V) and (VI)] show similar conformations and hydrogen‐bonding patterns. The C=N—NH—C=O group is planar, but the plane of the phenyl ring of the benzoyl group is rotated by about 30° with respect to that of the keto group [except for (IV), where the groups are coplanar]. Only in the amide group of (VIII) is the N—H group syn to the C=O bond, whereas the seven other compounds exhibit the anti conformation. Unless prevented by steric hindrance, N—H...O hydrogen bonds help to stabilize the crystal structure, which leads to infinite chains or dimers depending upon the molecular conformation. The molecular packing is supported by intermolecular C—H...O interactions. In the crystal structure of (VII), the methanol solvent molecule participates in two strong hydrogen bonds and two weak C—H...O interactions, thus acting as a link between the molecular chains.     

Transition‐metal‐catalyzed aminations and aziridinations of C?H and CC bonds with iminoiodinanes

Catalytic insertion or addition of a metal‐imido/nitrene species, generated from reaction of a transition‐metal catalyst with iminoiodanes, to C? H and C?C bonds offers a convenient and atom economical method for the synthesis of nitrogen‐containing compounds. Following this groundbreaking discovery during the second half of the last century, the field has received an immense amount of attention with a myriad of impressive metal‐mediated methods for the synthesis of amines and aziridines having been developed. This review will cover the significant progress made in improving the efficiency, versatility and stereocontrol of this important reaction. This will include the various iminoiodanes, their in situ formation, and metal catalysts that could be employed and new ligands, both chiral and non‐chiral, which have been designed, as well as the application of this functional group transformation to natural product synthesis and the preparation of bioactive compounds of current therapeutic interest. DOI 10.1002/tcr.201100018     

Spectral domain optical coherence tomography imaging with an integrated optics spectrometer

We designed and fabricated an arrayed-waveguide grating (AWG) in silicon oxynitride as a spectrometer for spectral domain optical coherence tomography (SD-OCT). The AWG has a footprint of only 3.0 cm × 2.5 cm, operates at a center wavelength of 1300 nm, and has 78 nm free spectral range. OCT measurements are performed that demonstrate imaging up to a maximum depth of 1 mm with an axial resolution of 19 μm, both in agreement with the AWG design parameters. Using the AWG spectrometer combined with a fiber-based SD-OCT system, we demonstrate cross-sectional OCT imaging of a multilayered scattering phantom.     

The combinatorics of N.G. de Bruijn

In memoriam: N.G. de Bruijn.     

Closed loop control for evolution inclusions

The existence of a closed loop control problem for quasi-variational inequalities is established. Feedback laws are given.     

Ab-initio valence bond calculations on the He-He potential curve using small bases

In studying methods for the ab-initio calculation of Van der Waals interactions which can be extended to larger molecules, we have tested the Valence Bond scheme on the He₂ system. This method looks promising, as it appears to yield in one consistent formalism both the attractive dipole—dipole terms and the repulsive exchange terms with reasonable accuracy, using only a simple orbital basis and a very small number of VB structures.     

Wavelength swept Ti:sapphire laser

In this study, we demonstrate, for the first time to our knowledge, electronic wavelength sweeping of a continuous wave Ti:sapphire laser using an acousto-optic tunable filter (AOTF). The dependence of the laser output on the sweeping frequency and on the spectral tuning range was investigated. The lasing up to maximum scan rate 11 kHz for 10 nm tuning range and 5 W pump power was achieved. We detected and quantified asymmetry in the output for opposite scan directions. We theoretically characterized the maximum sweeping frequency for swept lasers with AOTFs and confirmed calculated results by measurements.