Acetylenedithiolate: alkyne complex formation renders it a dithiolate chelate ligand

The isostructural complexes [{Tp'W(CO)(2)(eta(2)-C(2)S(2))}(2)M] (M = Ni, Pd, Pt) show that the eta(2)-C,C'-alkyne complexes of acetylenedithiolate at [Tp'W(CO)(2)](+) can generally act as dithiolate chelate ligands, leading to dithiolene type complexes.     

Analysis of medazepam, diazepam, and metabolites in plasma by gas-liquid chromatography with electrolytic conductivity detection.

An improved electrolytic conductivity detector allowed the gas-liquid chromatographic analysis of medazepam, diazepam, and major metabolites in 2 ml plasma at concentrations of 20 microgram/l. The detector had a sensitivity limit of less than 1 ng (or 100 pg nitrogen) when operated in the nitrogen-selective mode and a nitrogen/carbon elemental selectivity ratio of greater than 100,000 compared to octadecane and cholesterol. Detector response when operated in various element-selective chemical modes was investigated, and its application to the analysis of the title compounds was compared to electron capture and flame ionization detection systems.     

Silylhydrazine und dimere N,N′‐Dilithium‐N,N′‐bis(silyl)hydrazide – Synthesen,Reaktionen, Isomerisierungen

Silylhydrazines and Dimeric N,N′‐Dilithium‐N,N′‐bis(silyl)hydrazides – Syntheses, Reactions, Isomerisations Di‐tert.‐butylchlorosilane reacts with dilithiated hydrazine in a molar ratio to give the N,N′‐bis(silyl)hydrazine, [(Me₃C)₂SiHNH]₂, ( 5 ). Isomeric tris(silyl)hydrazines, N‐difluorophenylsilyl‐N′,N′‐bis(dimethylphenylsilyl)hydrazine ( 7 ) and N‐difluorophenylsilyl‐N,N′‐bis(dimethylphenylsilyl)hydrazine ( 8 ) are formed in the reaction of N‐lithium‐N′‐N′‐bis(dimethylphenylsilyl)hydrazide and F₃SiPh. Isomeric bis(silyl)hydrazines, (Me₃C)₂SiFNHNHSiMe₂Ph ( 9 ) and (Me₃C)₂‐ SiF(PhMe₂Si)N–NH₂ ( 10 ) are the result of the reaction of di‐tert.‐butylfluorosilylhydrazine and ClSiMe₂Ph in the presence of Et₃N. Quantum chemical calculations for model compounds demonstrate the dyotropic course of the rearrangement. The monolithium derivative of 5 forms a N‐lithium‐N′,N′‐bis(silyl)hydrazide ( 11 ). The dilithium salts of 5 ( 13 ) and of the bis(tert.‐butyldiphenylsilyl)hydrazine ( 12 ) crystallize as dimers with formation of a central Li₄N₄ unit. The formation of 12 from 11 occurs via a N′ → N‐silyl group migration. Results of crystal structure analyses are reported.     

Synthesis of [6,n] cis-fused ring compounds via Cr-mediated dearomatisation-ring-closing metathesis

cis-Fused [6,8], [6,7], [6,6] and [6,5] ring systems containing a cyclohexadiene ring unit, a cycloenone ring and a quaternary carbon at the ring junction were obtained in only two steps from [Cr(CO)3(eta6-p-methoxyphenyl oxazoline)]. The sequence proceeds via diastereoselective addition of three C-substituents across an arene double bond, followed by allylation and ring closing metathesis (RCM). RAMP-hydrazone and (R)-isopropyloxazoline were used as chiral auxiliaries to provide, after removal of the auxiliaries, the enantiomerically highly enriched [6,7] cis-fused system.     

Solving a Network Design Problem

Industrial optimization applications must be “robust” i.e., they must provide good solutions to problem instances of different size and numerical characteristics, and continue to work well when side constraints are added. This paper presents a case study that addresses this requirement and its consequences on the applicability of different optimization techniques. An extensive benchmark suite, built on real network design data, is used to test multiple algorithms for robustness against variations in problem size, numerical characteristics, and side constraints. The experimental results illustrate the performance discrepancies that have occurred and how some have been corrected. In the end, the results suggest that we shall remain very humble when assessing the adequacy of a given algorithm for a given problem, and that a new generation of public optimization benchmark suites is needed for the academic community to attack the issue of algorithm robustness as it is encountered in industrial settings.     

Transmutation studies using SSNTD and radiochemistry and the associated production of secondary neutrons

Experiments using 1.5 GeV, 3.7 GeV and 7.4 GeV protons from the Synchrophasotron, LHE, JINR, Dubna, Russia, on extended Pb- and U-targets were carried out using SSNTD and radiochemical sensors for the study of secondary neutron fluences. We also carried out first transmulation studies on the long-lived radwaste nuclei ¹²⁹I and ²³⁷Np.

In addition, we carried out computer code simulation studies on these systems using LAHET and DCM/CEM codes. We have difficulties to understand rather large transmutation rates observed experimentally when they are compared with computer simulations. There seems to be a rather fundamental problem understanding the large transmutation rates as observed experimentally in Dubna and CERN, as compared to those theoretical computer simulations mentioned above.     

Identification and Tracking-Control for an Optomechatronical Image Derotator Using Neural Networks

In this paper an optomechatronical image derotator is used for vibration measurements on rotating objects. First of all, the concept of the derotator is explained and it is shown that the phase position and the rotational velocity of the derotator and the measurement object have to be aligned. Therefore, a highly dynamic tracking-control is needed. Considering the nonlinear friction of the synchronous motor, a model of the system which considers this non-linearity is evolved. This is accomplished by using neural networks for the approximation of the friction term. In this case General Regression Neural Networks (GRNN) are used for the learning algorithm. Moreover, the system's parameters, eg. the friction term and the inertia, are identified based on the nonlinear model. Then a feedback control is designed by using the controllable canonical form through feedback linearization. Finally, the results of vibration measurements on a rotating blisk using the nonlinear control concept for the derotator are shown. (© 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)