Smart light-responsive supramolecular materials have been extensively investigated in the past decade, but so far the impact of metal coordination on hierarchical supramolecular structures of ...light-responsive building blocks has remained nearly unexplored. Herein, we unravel the hierarchical self-assembly of a small π-conjugated azo-containing pyridyl ligand that is able to respond to UV-light and metal complexation. The ligand self-assembles in an antiparallel fashion into long twisted fibers, which are then disassembled upon photoisomerization of the azobenzene groups, resulting in shorter rigid rods with a different packing motif. Complexation of Pd(ii) ions enhances the cooperativity of the aggregation and induces a molecular rearrangement into slipped stacks with subsequent formation of long thin fibers. These are then transformed into thinner, shorter rods upon light irradiation. The observed different light-responsiveness, besides clearing up the influence of metal coordination and light irradiation in self-assembly processes, paves the way towards the design of novel supramolecular photochromic systems.
Shone's syndrome is a rare congenital anomaly defined as the presence of at least two of the following heart obstructions: a mitral supravalvular ring, a “parachute” mitral valve stenosis, subaortic ...stenosis, and aortic coarctation. A 58‐year‐old man presented with a mitral ring and a “parachute” mitral valve on two‐dimensional transthoracic echocardiography, raising suspicion of Shone's syndrome. Three‐dimensional transesophageal echocardiography revealed a subannular mitral ring inserted directly on the mitral leaflets, thus acting as a “valvar ring.” This distinction can have therapeutic implications as a “valvar” mitral ring could require valve repair or replacement, instead of simple resection.
Wavelength routing algorithms (WRAs) aware of Physical layer impairments (PLIs) have been proposed in order to manage the establishment of optical paths in wavelength-switched optical networks. ...However, if optical nodes incorporate regenerators/wavelength converters, PLI-aware WRAs should be devised in order to incorporate error accumulation in the signal in the PLI estimation and relaxation of the wavelength continuity constraint in the path calculation. In this paper, we utilize a new bit error rate performance estimation in combination with the PLI-aware WRA in order to systematically investigate the role of regeneration and wavelength conversion in optical networks. Based on the outcomes of the study, we also propose a path establishment algorithm that is based on the "instant" physical properties of the path and can dynamically adapt to the network state. This is proven beneficial as far as the blocking performance is concerned as it circumvents the weaknesses that appear in the traditional shortest distance path establishment algorithms in a PLI-aware environment that operates without the wavelength continuity constraint.
Cooperative π–π interactions and H‐bonding are frequently exploited in supramolecular polymerization; however, close scrutiny of their mutual interplay has been largely unexplored. Herein, we compare ...the self‐assembly behavior of a series of C2‐ and C3‐symmetrical oligophenyleneethynylenes differing in their amide topology (N‐ or C‐centered). This subtle structural modification brings about drastic changes in their photophysical and supramolecular properties, highlighting the reciprocal impact of H‐bonding vs. preorganization on the evolution and final outcome of supramolecular systems.
To match or not to match: Detailed self‐assembly studies of a series of C2‐ and C3‐symmetrical π‐systems that differ in the amide connectivity (N‐ vs. C‐centered) were used to examine the reciprocal impact of H‐bonding and preorganization on the evolution of self‐assembled structures.
Optical Crossconnects (OXC) are indispensable for the proliferation of broadband services. Next generation OXCs should be dynamically reconfigurable, to render the optical layer flexible and agile, ...cost competitive, in order to be a viable alternative to fully electronic solutions and multi-service, i.e. to be able to handle both optical circuits and packets equally well. In this work, an evolutionary migration scenario from semi-static to dynamically reconfigurable broadcast-and-select OXCs is presented. The cornerstone of this approach is modularity in both the node architecture and the corresponding functionality, since these two are inextricably linked. Here, the three evolutionary steps of a modular broadcast-and-select architecture are presented, their principle of operation is explained and their complexity is analyzed. The key building-blocks to implement these OXCs are optical switching elements operating in a gated mode and tunable wavelength converters. Concerning the physical performance of these architectures, an important consideration is that node capacity is traded for higher node cascadeability. This trade-off is studied extensively considering a combination of different switching technologies and optical components. Moreover, the 2R regenerative properties of the all-optical and optoelectronic wavelength converters play a key role in the node cascadeability assessment which is otherwise compromised by OSNR limitations. For this reason, analytical models providing an insight on how certain physical mechanisms are leading to performance degradation are used. The final assessment is made using a commercial simulation tool, allowing the derivation of conclusions for the size of the transparent islands.
The latest advancements in semiempirical Hamiltonians have inspired new confidence for the supramolecular computational predictivity. The advanced accuracy of newly developed semiempirical methods is ...offered for computations of what can provide a valuable database of molecular tuning recommendations for the synthesis of new supramolecular materials. In this work the very versatile and impactful porphyrin is employed for examination of the first basic chemical tuning factors that may drive specific aggregation motifs. The 1D motifs are examined as a function of peripheral substituent steric bulk. Subsequently, a 1D‐wire versus a 3D‐square motif is investigated as a function of the metal–ligand effect. For the first time, an interesting effect of misprediction of semiempirical computations is encountered for a small class of these aggregates and is briefly examined with a conformational search analysis. These findings encourage further in silico work which is greatly required for diminishing the current discovery bottleneck in supramolecular chemistry.
Chemical tuning in self‐assembly: The peripheral functionalisation of poprhyrinic mer units leads to drastic changes in supramolecular assembly motif. The fine supramolecular architectural details and degree of dimentionality can be controlled with the appropriate choice of peripheral substituents in the mer units. Fast systematic predictions are made with GFN2‐xTB.
The TOTEM experiment has made a precise measurement of the elastic proton–proton differential cross-section at the centre-of-mass energy s=8 TeV based on a high-statistics data sample obtained with ...the β⁎=90 m optics. Both the statistical and systematic uncertainties remain below 1%, except for the t-independent contribution from the overall normalisation. This unprecedented precision allows to exclude a purely exponential differential cross-section in the range of four-momentum transfer squared 0.027<|t|<0.2 GeV2 with a significance greater than 7 σ. Two extended parametrisations, with quadratic and cubic polynomials in the exponent, are shown to be well compatible with the data. Using them for the differential cross-section extrapolation to t=0, and further applying the optical theorem, yields total cross-section estimates of (101.5±2.1) mb and (101.9±2.1) mb, respectively, in agreement with previous TOTEM measurements.
This paper presents the results of the optical packet switched network (OPSnet) project, which investigated the design of an asynchronous optical packet switch suitable for the core of an optical ...transport network (OTN). The requirements for the switch were to control and route variable-length packets transmitted at bit rates beyond 100 Gbit/s. The subsystems and techniques used are analyzed and presented. Fast header encoding and passive decoding is based on the differential phase-shift keying (DPSK) method. The dual-pump four-wave mixing (d-p FWM) wavelength-conversion technique, in combination with an arrayed waveguide grating (AWG), is utilized for packet switching. An advanced and fully controllable mechanism for the packet-switch control is presented, which is implemented on field programmable gate array (FPGA) technology. The control wavelength is generated using a tunable laser, the actual wavelength and new header values are provided utilizing fast header recognition and look-up tables. The integration of the subsystems is discussed, and the results of a four-output port asynchronous packet-switch demonstrator operating at 40 Gbit/s are presented. Finally, the switch limitations are examined and design issues are discussed.
In this note we generalize an upper bound given in Guggenheimer et al. (College Math. J. 26(1) (1995) 2) for the condition number of a matrix as a function of the determinant, the Frobenius norm and ...of
k singular values. If no singular value is known it is possible to derive an upper bound for the condition number applying lower and upper bounds for the product of a subset of singular values.
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