Laser coupling to single-mode fibre using graded-index lenses and compact disc 1.3 ?m laser package

A 1.3 ?m laser in a compact disc package is coupled to single-mode fibre using two graded-index lenses in a nearly confocal scheme. An increase in the alignment tolerance at the lens-lens interface by a factor of six suggests the design for a potentially very low-cost connectorised laser package. The coupling efficiency of approx. 6% (?12 dB) is shown to be adequate for local loop applications.     

Comparison of Force Fields on the Basis of Various Model Approaches—How To Design the Best Model for the [CnMIM][NTf2] Family of Ionic Liquids

In this contribution, we present two new united‐atom force fields (UA‐FFs) for 1‐alkyl‐3‐methylimidazolium bis(trifluoromethylsulfonyl)imide [C_nMIM][NTf₂] (n=1, 2, 4, 6, 8) ionic liquids (ILs). One is parametrized manually, and the other is developed with the gradient‐based optimization workflow (GROW). By doing so, we wanted to perform a hard test to determine how researchers could benefit from semiautomated optimization procedures. As with our already published all‐atom force field (AA‐FF) for [C_nMIM][NTf₂] (T. Köddermann, D. Paschek, R. Ludwig, ChemPhysChem­ 2007, 8, 2464 ), the new force fields were derived to fit experimental densities, self‐diffusion coefficients, and NMR rotational correlation times for the IL cation and for water molecules dissolved in [C₂MIM][NTf₂]. In the manual force field, the alkyl chains of the cation and the CF₃ groups of the anion were treated as united atoms. In the GROW force field, only the alkyl chains of the cation were united. All other parts of the structures of the ions remained unchanged to prevent any loss of physical information. Structural, dynamic, and thermodynamic properties such as viscosity, cation rotational correlation times, and heats of vaporization calculated with the new force fields were compared with values simulated with the previous AA‐FF and the experimental data. All simulated properties were in excellent agreement with the experimental values. Altogether, the UA‐FFs are slightly superior for speed‐up reasons. The UA‐FF speeds up the simulation by about 100 % and reduces the demanded disk space by about 78 %. More importantly, real time and efforts to generate force fields could be significantly reduced by utilizing GROW. The real time for the GROW parametrization in this work was 2 months. Manual parametrization, in contrast, may take up to 12 months, and this is, therefore, a significant increase in speed, though it is difficult to estimate the duration of manual parametrization.     

Water‐soluble metalated and non‐metalated A2B‐ and A3‐corrole/amino acid conjugates: syntheses,characterization and properties

In this study, novel water‐soluble corrole amino acid conjugates were synthesized and characterized. The coupling reaction of A₂B‐ and A₃‐corroles with glycine ethyl ester and taurine under strong basic conditions proved to be successful and yielded di‐ and trifunctionalized corrole amino acid conjugates in good yields. The subsequent metalation of the corrole/amino acid conjugates broadens the scope for applications considerably. As examples, we herein show the catalytic activity of the Mn(III) A₃‐corrole towards O₂ evolution. First we employed tert‐butyl hydroperoxide (t‐BuOOH) as oxidant to obtain the Mn(V)oxo species and tetrabutyl ammonium hydroxide (TBAH) as hydroxide donor agent. Furthermore, the binding properties of the non‐metalated and the Mn(III) A₃‐corrole/amino sulfonic acid conjugates and transport of proteins were investigated and the conjugates exhibited binding to human serum albumin (HSA). Finally, a novel Ga(III) A₃‐corrole/amino sulfonic acid derivative was synthesized and we briefly describe the photophysical properties of this compound. Copyright © 2013 John Wiley & Sons, Ltd.     

Cobalt and Iron Stabilized Ketyl,Ketiminyl and Aldiminyl Radical Anions

Carbonyl and iminyl based radical anions are reactive intermediates in a variety of transformations in organic synthesis. Herein, the isolation of ketyl, and more importantly unprecedented ketiminyl and aldiminyl radical anions coordinated to cobalt and iron complexes is presented. Insights into the electronic structure of these unusual metal bound radical anions is provided by X-Ray diffraction analysis, NMR, IR, UV/Vis and Mössbauer spectroscopy, solid and solution state magnetometry, as well as a by a detailed computational analysis. The metal bound radical anions are very reactive and facilitate the activation of intra- and intermolecular C−H bonds.     

Die Titration der Alkalien in Trinkw?ssern

Zusammenfassung Die titrimetrische Alkalibestimmung in Trinkwässern nach Wagner-Kionka in der Ausführung von Tillmans-Neu ergab in den Händen der Verfasser unregelmäßige Werte. Die Abweichungen ließen sich nicht aus den Kaliumgehalten der Leitungswasser erklären, ebensowenig aus dem Umstand, daß in den genannten Vorschriften den Blindwerten der Reagenzien in ungenügender Weise Rechnung getragen wird.Die Verfasser haben die Grundlagen des oben genannten titrimetrischen Verfahrens untersucht, insbesondere die folgenden Fehlerquellen: Alkaligehalt der Reagenzien, Mitreißen von Alkalien durch die Niederschläge, unvollständiges Ausfällen des Bariumcarbonats und den Titrierfehler bei der Titration bis zum p_H-Wert von 4,5. Anläßlich dieser Untersuchungen wurden zwei neue Analysenvorschriften ausgearbeitet, die in den Händen verschiedener Analytiker rasche und zuverlässige Ergebnisse lieferten.     

Performance of 4*4 optical crossbar switch utilising acousto-optic deflector

A multicasting photonic space switch reconfigurable in 50 ns is demonstrated utilising commercially available acousto-optic Bragg cells at lambda =0.83 mu m. Insertion loss of 15 dB, extinction ratio of 33 dB, crosstalk of -24 dB and polarisation difference of 0.8 dB are reported.<>     

Microchips for the Investigation of Thermal and Electrical Properties of Individual Nanowires

This paper focuses on the determination of thermal and electrical properties of individual thermoelectric nanowires, primarily bismuth and bismuth compound nanowires, as functions of their crystallinity, diameter, and composition. For measurements of the Seebeck coefficient and the electrical and thermal conductivity, specially designed microchips have been developed and employed. Finite-element simulations demonstrate that the temperature profiles of the microchips provide suitable temperature gradients for Seebeck-effect measurements and heat-sink conditions for thermal conductivity investigations. First measurements of thermal conductivity of metallic nanowires and of Seebeck coefficients of granular nanowires prepared by focused electron-beam-induced deposition are presented. Some of these results are discussed in the framework of finite-size-effect theory.     

Utilization of electroplating to lock fibers for use in opticaldevice packaging

An electroplating technique for permanently fixing single-mode fibers into position in optical device packages is described. In this technique, the fiber is mounted in a metal tube and aligned to an optical device mounted on a metal substrate. The fiber is in close proximity to the substrate and a flexible conductive gel is used to connect the two electrically. The fiber, gel, and substrate thus form the plating cathode. When immersed in a plating bath with an anode inserted, metal can be deposited across the gel, forming a strong metal bridge between the fiber and substrate, locking the fiber into position. Under appropriate conditions, misalignments within ±1 μm during the plating process have been observed. This technique was used to package a laser diode transmitter, which locked the laser-to-fiber alignment to within 0.7 μm, or 0.1 dB of the optimum coupled power     

Synthesis and characterization of a stable bismuth(III) A3-corrole

An efficient metalation procedure for bismuth complexes with meso-substituted corrole ligands is presented. Reaction of 5,10,15-tris-pentafluorophenylcorrole H(3)(TpFPC) with Bi{N(SiMe(3))(3)} converts the free ligand H(3)(TpFPC) to a neutral low-valent species Bi(TpFPC), which has been characterized by different spectroscopic techniques. (Spectro)electrochemical studies were performed in order to describe the redox potentials of the Bi(TpFPC) complex and to ascribe the sites of electron transfer. The first crystal structure of a bismuth corrole is presented and compared to the geometry-optimized molecular structure obtained with density functional theory (DFT) calculations. We show an example of a 4-coordinate metallocorrole with a very large out-of-plane displacement and significant doming. The electronic structure of the novel bismuth corrole system is discussed in detail. Time-dependent DFT results support the proposed assignment of electronic transitions observed for the Bi(TpFPC) derivative. To account for the reactivity we investigated the photocatalytic properties of the Bi(TpFPC) complex.