Internal quality control in forensic DNA analysis

The trail from initial evidence examination to a DNA profile reported to match a suspect is long and complex. The different nature and great variability in the biological and DNA evidence to be recovered and analyzed, add to this complexity. Internal quality controls play an important role in maintaining a high-quality performance in daily forensic biology and DNA profiling practice. In many cases are empirical rather than analytical approaches adopted. Obviously, despite the fact of being necessary, the internal quality controls performed still need to be kept rational at a limited, yet acceptable level. Quality control from a forensic biology and DNA profiling horizon has a wider context and does not only concern obvious fit-for-purpose verifications of analytical processes, chemicals, or reagents in daily routine practice. It also includes control on computerized laboratory management and expert systems, laboratory environmental DNA monitoring, and the use of elimination DNA databases. In addition, a structured recording and handling of non-conformances and “near failures” is essential. Proper management of the non-conformances supports continuous quality improvements by learning from the errors occurring in daily practice. High transparency of non-conformances is important not only for internal improvements, but also for the criminal justice system as well as to maintain public confidence and trust. Together the quality controls used aim at maintaining evidence and DNA sample integrity and to accomplish correct results and interpretations by verifying that methods used data transfers and interpretations made are correct and performed according to validated and accredited conditions.     

Nature of halide binding to the molybdenum site of sulfite oxidase

Valuable information on the active sites of molybdenum enzymes has been provided from both Mo(V) electron paramagnetic resonance (EPR) spectroscopy and X-ray absorption spectroscopy (XAS). One of three major categories of Mo(V) EPR signals from the molybdenum enzyme sulfite oxidase is the low-pH signal, which forms in the presence of chloride. Two alternative structures for this species have been proposed, one in which the chloride is coordinated directly to Mo and a second in which chloride is held in the arginine-rich basic pocket some 5 ? from Mo. Here we present an independent assessment of the structure of this species by using XAS of the analogous bromide and iodide complexes. We show that there is no evidence of direct Mo-I coordination, and that the data are consistent with a structure in which the halide is bound at ～5 ? from Mo.     

Monetary and relative scorecards to assess profits in consumer revolving credit

This paper presents for the first time a relative profit measure for scoring purposes and compares results with those obtained from monetary scores. The suggested measure is the cumulative profit relative to the outstanding debt. It can also be interpreted as the percentage coverage against default. Monetary and relative measures are compared with both being estimated using direct and indirect methods. Direct scores are obtained from borrower attributes, while indirect scores are predicted using the estimated probabilities of default and repurchase. Results show that specific segments of customers are profitable in both monetary and relative terms. The best performing indirect models use the probabilities of default within 12 months on books. This agrees with existing banking practice of default estimation. Direct models outperform indirect models. Relative scores would be preferred under more conservative standpoints towards default because of unstable conditions and if the aim is to penetrate relatively unknown segments. Further ethical considerations justify their use in an inclusive lending context.     

Ytterbium and erbium derivatives of 2-methoxyethanol and their use in the thin film deposition of Er-doped Yb3Al5O12

We have proved different methods for yttrium and erbium 2-methoxyethoxides preparation. Our aim was to prepare a solution applicable at the subsequent sol–gel preparation of Yb₃Al₅O₁₂ garnet thin films. We tested the direct reaction of a metal with 2-methoxyethanol in the presence of HgCl₂, the electrolytic dissolution of metals, an alcohol interchange using isopropoxides and, finally, the exchange reaction of acetates with 2-methoxyethanol. Because our demand was to prepare a solution without the necessity of purification, we omitted chlorides as a source of cations. The formation of the metal alkoxides was examined by IR spectroscopy in each case. Both exchange reactions were fully successful; only in the case of acetate use, the arising acetic acid forms ester immediately. The direct reaction of metals with the alcohol did not achieve a full yield; on the other hand, after electrolysis application, the metals dissolved readily. However, in both cases, the filtration of either unreacted metal (direct reaction) or eroded metal pieces (electrolysis) was necessary. Because the filtration has to be processed under inert atmosphere these methods are less convenient for the subsequent use in the sol–gel deposition. Er:Yb₃Al₅O₁₂ thin films deposited on silicon substrates were also prepared using the two appropriate intermediates—the solutions prepared either from acetates or isopropoxides. Both layers were monophase; however, the microstructure and luminescent properties were influenced by the solution used. The Er:YbAG layers exhibited the sharp and discreet luminescence peaks of the Er³⁺ transition ⁴I_13/2 → ⁴I_15/2.     

Directly heated etching stand for electrochemical treatment of track detectors

The directly electrically heated etching stand has been developed for the electrochemical treatment of track detectors to avoid the time consuming overnight pre-heating and to simplify the procedure. The large plate electrode containing several heating elements on its rear side creates the main part of the etching stand. The temperature of the electrode connected to the control unit is variable within 30–70°C. Two types of etching stands were tested. The uniformity of the temperature distribution on the electrode surface, heating rate and stability of temperature were studied as the main parameters and the results are presented. The technical solution allows to construct smaller (even portable) devices for the electrochemical etching.     

Catalytic applications of 1,2,4-diazaphospholide-based ruthenium complexes in the Heck reaction

The palladium-catalyzed Heck reaction was effected with two ruthenium complexes bearing unique heterocyclic 1,2,4-diazaphospholide ligands that contain sp²-hybridized phosphorus atoms.     

Label‐Free Nanoimaging of Neuromelanin in the Brain by Soft X‐ray Spectromicroscopy

A hallmark of Parkinson's disease is the death of neuromelanin‐pigmented neurons, but the role of neuromelanin is unclear. The in situ characterization of neuromelanin remains dependent on detectable pigmentation, rather than direct quantification of neuromelanin. We show that direct, label‐free nanoscale visualization of neuromelanin and associated metal ions in human brain tissue can be achieved using synchrotron scanning transmission x‐ray microscopy (STXM), through a characteristic feature in the neuromelanin x‐ray absorption spectrum at 287.4 eV that is also present in iron‐free and iron‐laden synthetic neuromelanin. This is confirmed in consecutive brain sections by correlating STXM neuromelanin imaging with silver nitrate‐stained neuromelanin. Analysis suggests that the 1s–σ* (C?S) transition in benzothiazine groups accounts for this feature. This method illustrates the wider potential of STXM as a label‐free spectromicroscopy technique applicable to both organic and inorganic materials.     

Label-Free Nanoimaging of Neuromelanin in the Brain by Soft X-ray Spectromicroscopy

A hallmark of Parkinson's disease is the death of neuromelanin-pigmented neurons, but the role of neuromelanin is unclear. The in situ characterization of neuromelanin remains dependent on detectable pigmentation, rather than direct quantification of neuromelanin. We show that direct, label-free nanoscale visualization of neuromelanin and associated metal ions in human brain tissue can be achieved using synchrotron scanning transmission x-ray microscopy (STXM), through a characteristic feature in the neuromelanin x-ray absorption spectrum at 287.4 eV that is also present in iron-free and iron-laden synthetic neuromelanin. This is confirmed in consecutive brain sections by correlating STXM neuromelanin imaging with silver nitrate-stained neuromelanin. Analysis suggests that the 1s–σ* (C−S) transition in benzothiazine groups accounts for this feature. This method illustrates the wider potential of STXM as a label-free spectromicroscopy technique applicable to both organic and inorganic materials.     

Observation of a CuII2(μ‐1,2‐peroxo)/CuIII2(μ‐oxo)2 Equilibrium and its Implications for Copper–Dioxygen Reactivity

Synthesis of small‐molecule Cu₂O₂ adducts has provided insight into the related biological systems and their reactivity patterns including the interconversion of the Cu^II₂(μ‐η²:η²‐peroxo) and Cu^III₂(μ‐oxo)₂ isomers. In this study, absorption spectroscopy, kinetics, and resonance Raman data show that the oxygenated product of [(BQPA)Cu^I]⁺ initially yields an “end‐on peroxo” species, that subsequently converts to the thermodynamically more stable “bis‐μ‐oxo” isomer (K_eq=3.2 at ?90 °C). Calibration of density functional theory calculations to these experimental data suggest that the electrophilic reactivity previously ascribed to end‐on peroxo species is in fact a result of an accessible bis‐μ‐oxo isomer, an electrophilic Cu₂O₂ isomer in contrast to the nucleophilic reactivity of binuclear Cu^II end‐on peroxo species. This study is the first report of the interconversion of an end‐on peroxo to bis‐μ‐oxo species in transition metal‐dioxygen chemistry.     

Improvement of switching properties and cascadability of an ultra-fast reconfigurable optical crosspoint switch matrix using DPSK payloads

In this paper, we demonstrate mitigation of pattern-induced degradation in an optical crosspoint switch (OXS) matrix by utilizing differential phase shift keying (DPSK) modulation format. We experimentally demonstrate 4 × 4 unicast optical packet switching and dynamic reconfiguration for 4-channel, 200 GHz spacing of RZ-DPSK payloads. Reconfigurable time as fast as 2 ns is achieved owing to the optimized control circuit and device fabrication. The power and wavelength dependence are obtained for the RZ-DPSK payload. We also investigate the cascadability of the OXS based on re-circulating loops. Due to the great suppression of the pattern effect in OXS, DPSK has shown dramatical improvement of switching properties compared to conventional ON-OFF keying (OOK) signal. The DPSK payload can outperform OOK for 3.2 dB after 9 hops optical switching.