The scanning electrochem. microscope was applied to drive the deposition of Ni(OH)2 structures. Nickel hydroxide was deposited from aq. solns. onto platinum surfaces as a result of changing the pH locally on the electrode surface. The increase in pH is driven by an oxidn.-redn. process, i.e., N,N'-dimethyl-4,4'-bipyridinium, MV2+, which is reduced at an ultramicroelectrode, diffuses to the surface where it is regenerated upon the redn. of protons, causing a local increase of pH and the deposition of Ni(OH)2. The different parameters that control the efficiency of the deposition, such as the pH and the concn. of the buffer, were examd. [on SciFinder(R)]
Summary: ``This work addresses code design and code selection rules under power and decoding delay constraints for an antipodal (BPSK) modulated and convolutionally encoded communication system. The system operates over a slowly-fading AWGN channel, described here by the `block fading' model. We specialize to coherent detection and maximum likelihood decoding with ideal channel information (the instantaneous fading values). The dominant design criterion in this scenario is the code diversity level in terms of blocks while the standard Hamming distance plays a secondary role. A code design procedure is presented along with a code-search algorithm. Performance results of a selected code are assessed via simulation and compared to those achieved by a Reed-Solomon code with erasure and error decoding.''
The dispersion of the second‐order optical nonlinearity in chromophoric self‐assembled stilbazolium films has been characterized in detail as a function of fundamental wavelength from 800 to 1600 nm using an optical parametric amplifier‐based measurement system. The second‐harmonic generation (SHG) spectrum exhibits a distinctive two‐photon resonance at ℏω=1.3 eV (960 nm). The maximum in the second‐order susceptibility coincides with a low‐energy chromophore‐centered charge‐transfer one‐photon excitation at 480 nm (2.6 eV). The experimental SHGdispersion values compare favorably with theoretical results computed using a semiempirical sum‐over‐states formalism. These indicate that the χ(2)response is dominated by an excitation along the long axis of the stilbazolium chromophore from the highest occupied to the lowest unoccupied molecular orbital.
Construction on inorganic oxide substrates of covalently self-assembled second-order nonlinear optical (NLO) materials containing a variety of acentrically organized high-β chromophores is investigated as a function of film deposition conditions. Structurally different chromophores exhibit varying packing arrangements on the surface. Changing the medium for the chromophorc deposition reaction on functionalized surfaces from a polar solvent to a nonpolar solvent and raising the temperature increases the chromophore number density on the surface and yields improved NLO response. These robust thin film materials show very high second harmonic generation (SHG) efficiencies with X(2)zzz for ∼ 25 Å thick monolayers of up to 7 × 10−7 esu at 1064 nm.
A glassy carbon electrode (GCE) coated with 4,7,13,16,21,24-hexaoxa-1,10-diazabicyclo[8.8.8.]hexacosane, Kryptofix-222, was used for the very sensitive and selective detn. of very low levels of mercury. A detection limit lower than 10-12 M (<0.2 ppt) was obtained applying anodic stripping voltammetry (ASV). The parameters that governed the sensitivity and possible interferences by other ions have been examd. in detail. The electrode has been successfully applied for detg. mercury in seawater, wastewater, and also in human saliva and amniotic fluid. The modified electrode exhibited high stability and, therefore, could be used repeatedly without mech. regeneration. [on SciFinder(R)]
Appeared also in his 'Judíos nuevos en Amsterdam' (1996) and in the French translation 'Les nouveaux-juifs d'Amsterdam' (1999). Appeared previously in French in 'XVIIe Siècle' 46 (1994).
Within the western Sephardic diaspora, Jewish communities remained, in principle, faithful to their family ties and took measures to protect the family and its prerogatives, in an effort to preserve cohesiveness. Marriages with non-Sephardic Jews were condemned and interclass marriages were discouraged. These attitudes intensified in the 17th and 18th centuries. The most acute problem was clandestine marriages flouting traditional norms. Such unions were seen as a threat to the stability of the social fabric. Parents and rabbis alike claimed the right to legitimize marriages by giving their consent.
Lay summary:
The article examines how governments conscript to the military minority ethnic groups that are potentially hostile to the state. The article finds that three primary methods are used; all employ compulsory conscription but rely on different motives: coercion on fear of punishment; ideology on belief in a political or moral duty; contract on the expectation of civil benefits. The article finds that contract is most likely to ensure both military service and wider societal integration.
Publication significance:
How can nation states conscript potentially hostile minority ethnic groups to the armed forces and ensure their allegiance to the state? It finds that negotiating contracts with leaders of ethnic groups that guarantee benefits for ethnic minorities in return for army service ultimately better serves state interests than relying on fear of punishment or ideological conviction. These findings have important implications for both theory and policy.
An attractive and challenging approach to the construction of robust, thin film materials with large second-order optical nonlinearities is the covalent self-assembly of aligned arrays of high-β molecular chromophores into multilayer superlattices. In this paper, we describe the dispersion of second harmonic generation (SHG) in a self-assembled (SA) monolayer containing a stilbazolium chromophore. The frequency-dependent measurements were performed on 25 Å thick monolayers on glass using a tunable (0.4–2 μm) light source based on optical parametric amplification (OPA). The SHG spectrum contains a clear two-photon resonance at hω = 1.3eV. The maximum in the second-order susceptibility coincides with a low energy chromophore-centered charge-transfer excitation at 480 nm. The experimental SHG dispersion values compare favorably with theoretical results computed using a sum-over-states (SOS) formalism. However, the measured values exhibit a somewhat broader band response than the theoretical curve, and the origin of this behavior is discussed.
