Cobalt(II)-selective membrane electrode based on N,N′-di(thiazol-2-yl)formimidamide

A new PVC-membrane electrode for Co²⁺ ions based on N,N′-di(thiazol-2-yl)formimidamide (TF) as membrane carrier has been developed. The electrode resulted in Nernstian response (29.5?±?0.4?mV decade^?1) for Co²⁺ ion over a wide concentration range (2.5?×?10^?7 ?1.0?×?10^?1?M) with a detection limit of 6.1?×?10^?8?M. The sensor has a response time of about 10?s, and can be used for at least 2 months without observing any deviation from the Nernstain response. The electrode revealed good selectivity towards cobalt(II) ion over a wide variety of alkali, alkaline earth, transition, and heavy metal ions and could be used in the pH range 2.0–7.0. The electrode was used for determination of Co²⁺ in real samples.     

Detection and identification of the designer benzodiazepine flubromazepam and preliminary data on its metabolism and pharmacokinetics

The appearance of pyrazolam in Internet shops selling ‘research chemicals’ in 2012 marked the beginning of designer benzodiazepines being sold as recreational drugs or ‘self medication’. With recent changes in national narcotics laws in many countries, where two uncontrolled benzodiazepines (phenazepam and etizolam), which were marketed by pharmaceutical companies in some countries, were scheduled, clandestine laboratories seem to turn to poorly characterized research drug candidates as legal substitutes. Following the appearance of pyrazolam, it comes with no surprise that recently, flubromazepam (7‐bromo‐5‐(2‐fluorophenyl)‐1,3‐dihydro‐2H‐1,4‐benzodiazepin‐2‐one), a second designer benzodiazepine, was offered on the market. In this article, this new compound was characterized using nuclear magnetic resonance, gas chromatography‐mass spectrometry (GC–MS), liquid chromatography–mass spectrometry (LC–MS/MS) and liquid chromatography quadrupole time‐of‐flight MS (LC–Q–ToF–MS). Additionally, a study was carried out, in which one of the authors consumed 4 mg of flubromazepam to gain preliminary data on the pharmacokinetic properties and the metabolism of this compound. For this purpose, serum as well as urine samples were collected for up to 31 days post‐ingestion and analyzed applying LC–MS/MS and LC–Q‐ToF‐MS techniques. On the basis of this study, flubromazepam appears to have an extremely long elimination half‐life of more than 100 h. One monohydroxylated compound and the debrominated compound could be identified as the predominant metabolites, the first allowing a detection of a consumption for up to 28 days post‐ingestion when analyzing urine samples in our case. Additionally, various immunochemical assays were evaluated, showing that the cross‐reactivity of the used assay seems not to be sufficient for safe detection of the applied dose in urine samples, bearing the risk that it could be misused in drug‐withdrawal settings or in other circumstances requiring regular drug testing. Furthermore, it may be used in drug‐facilitated crimes without being detected. Copyright © 2013 John Wiley & Sons, Ltd.     

Carbon monoxide isotope enrichment and separation by pressure swing adsorption

Simulations of three different 3-bed 3-step pressure swing adsorption (PSA) cycles were carried out to study the enrichment and recovery of ¹⁴CO from an isotopic mixture of ¹⁴CO, ¹³CO and ¹²CO using NaX zeolite. Each PSA cycle included feed pressurization/feed (FP/P), heavy reflux (HR) and countercurrent depressurization (CnD) steps; they differed only in the way the CnD step was carried out: PSA Cycle I was carried out under total reflux (i.e., with no ¹⁴CO heavy product production); PSA Cycle II was carried out with discontinuous ¹⁴CO heavy product production; and PSA Cycle III was carried out with continuous ¹⁴CO heavy product production. The effects of the CnD step valve coefficient (c _v ), heavy reflux ratio (R _R ), and cycle time (t _cyc ) on the PSA process performance were determined in terms of the ¹⁴CO enrichment, ¹⁴CO recovery and CO feed throughput. The results showed that there was essentially no limit to the extent of the ¹⁴CO enrichment, despite the inherently low ¹⁴CO/¹²CO (1.05) and ¹⁴CO/¹³CO (1.12) separation factors for these isotopes on NaX zeolite. Under total reflux an optimum c _v was found for the CnD step and ¹⁴CO enrichments as high as 152 were obtained. Using the optimum c _v under finite reflux, a ¹⁴CO enrichment approaching 20 and a ¹⁴CO recovery approaching 100 % were easily achieved with discontinuous (PSA Cycle II) or continuous (PSA Cycle III) ¹⁴CO heavy product production. There was essentially no difference in the performance of PSA Cycles II and III, a counterintuitive result. The ¹⁴CO enrichment and the ¹⁴CO recovery both increased with decreasing CO feed throughputs and higher R _R , which were always very close to unity.     

Metal Sulfide Nanoparticle Synthesis with Ionic Liquids – State of the Art and Future Perspectives

Metal sulfides are among the most promising materials for a wide variety of technologically relevant applications ranging from energy to environment and beyond. Incidentally, ionic liquids (ILs) have been among the top research subjects for the same applications and also for inorganic materials synthesis. As a result, the exploitation of the peculiar properties of ILs for metal sulfide synthesis could provide attractive new avenues for the generation of new, highly specific metal sulfides for numerous applications. This article therefore describes current developments in metal sulfide nanoparticle synthesis as exemplified by a number of highlight examples. Moreover, the article demonstrates how ILs have been used in metal sulfide synthesis and discusses the benefits of using ILs over more traditional approaches. Finally, the article demonstrates some technological challenges and how ILs could be used to further advance the production and specific property engineering of metal sulfide nanomaterials, again based on a number of selected examples.     

Effect of nonlinear correlations on the statistics of return intervals in multifractal data sets

We study the statistics of return intervals between events above a certain threshold in multifractal data sets without linear correlations. We find that nonlinear correlations in the record lead to a power-law (i) decay of the autocorrelation function of the return intervals, (ii) increase in the conditional return period, and (iii) decay in the probability density function of the return intervals. We show explicitly that all the observed quantities depend both on the threshold value and system size, and hence there is no simple scaling observed. We also demonstrate that this type of behavior can be observed in real economic records and can be used to improve considerably risk estimation.     

Excellent passivation of thin silicon wafers by HF‐free hydrogen plasma etching using an industrial ICPECVD tool

In this work, hydrogen plasma etching of surface oxides was successfully accomplished on thin (～100 µm) planar n‐type Czochralski silicon wafers prior to intrinsic hydrogenated amorphous silicon [a‐Si:H(i)] deposition for heterojunction solar cells, using an industrial inductively coupled plasma‐enhanced chemical vapour deposition (ICPECVD) platform. The plasma etching process is intended as a dry alternative to the conventional wet‐chemical hydrofluoric acid (HF) dip for solar cell processing. After symmetrical deposition of an a‐Si:H(i) passivation layer, high effective carrier lifetimes of up to 3.7 ms are obtained, which are equivalent to effective surface recombination velocities of 1.3 cm s^–1 and an implied open‐circuit voltage (V_oc) of 741 mV. The passivation quality is excellent and comparable to other high quality a‐Si:H(i) passivation. High‐resolution transmission electron microscopy shows evidence of plasma‐silicon interactions and a sub‐nanometre interfacial layer. Using electron energy‐loss spectroscopy, this layer is further investigated and confirmed to be hydrogenated suboxide layers. (© 2015 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim)     

Propane‐1,2‐diols from Dilactides,Oligolactides, or Poly‐L‐lactic Acid (PLLA): From Plastic Waste to Chiral Bulk Chemicals

The preparation of racemic or enantioenriched propane‐1,2‐diol from dilactides, oligolactides, or poly‐L ‐lactic acid (PLLA) is described. The transformation is carried out as tandem reactions in MeOH, covering hydrolysis and subsequent hydrogenation by using copper chromite as a catalyst. The starting material present undesired side products of the PLLA synthesis or PLLA waste.     

Dynamic mechanical investigations of different substituted cellulose o-silyl ethers

In contrast to many cellulose derivatives, the cellulose O-silyl ethers with bulky side groups exhibit scarcely a change in glass transition temperature by a variation of the degree of substitution (DS) or degree of polymerization (DP) or by introducing phenyl carbamate groups for the remaining hydroxyls along the main chain. However, a substitution of these hydroxyls by flexible acetate groups lowers the glass transition temperature considerably. The secondary dispersion (relaxation) behavior is strongly influenced by the various substituents and can be correlated to specific motions of the molecules. The dynamic mechanical properties are also dependent on the kind of preconditioning of the samples.