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A novel device that demodulates both quadratures of the optical differential quadrature phase-shift keying (DQPSK) format in a single interferometer by using a 4 × 4 star coupler was demonstrated. Simultaneous measurements of both DQPSK quadratures at 42.7 Gb/s are also presented. [ABSTRACT FROM PUBLISHER]

A compact and simple silica-waveguide 10-Gb/s tunable optical dispersion compensator (ODC) that works with uncontrolled wavelength transmitters by tracking the signal wavelength is demonstrated. Transmissions at 10.7 Gb/s over 5100 ps/nm of dispersion with a duobinary signal using a single pass of the ODC and 3825 ps/nm of dispersion with an unchirped non-return-to-zero signal using a double pass of the ODC are shown. [ABSTRACT FROM PUBLISHER]

This paper describes the demonstration of an improved eight-channel coarse wavelength-division multiplexer. The fully packaged channel losses range from 2.3 to 3.9 dB, the 1-dB bandwidth is 16.3 nm, and the crosstalk is <-28dB. This silica-waveguide device could have very low cost. [ABSTRACT FROM PUBLISHER]

Laser-polarized 129Xe and a high-Tcsuperconducting quantum interference device (SQUID) are used to obtain magnetic resonance images in porous materials at a magnetic field of 2.3 mT, corresponding to a Larmor frequency of 27 kHz. Image resolution of 1 mm is obtained with gradients of only 1 mT/m. The resolution of xenon chemical shifts in different physicochemical environments at ultralow fields is also demonstrated. Details of the circulating flow optical pumping apparatus and the SQUID spectrometer are presented. [Copyright &y& Elsevier]

The application of a core–shell architecture allows the formation of a polymer-coated metal–organic framework (MOF) maintaining high surface area (2289–2857 m2 g−1). The growth of a MOF shell from a MOF core was used to spatially localize initiators by post-synthetic modification. The confinement of initiators ensures that polymerization is restricted to the outer shell of the MOF. [ABSTRACT FROM AUTHOR]

A 2D zirconium-based microporous coordination polymer derived from the tritopic linker 1,3,5-(4-carboxylphenyl)benzene, UMCM-309a, has been synthesized. This noninterpenetrated material possesses a Zr6(μ3-O)4(μ3-OH)4(RCO2)6(OH)6(H2O)6 cluster with six hexagonal-planar-coordinated linkers. UMCM-309a is stable in an aqueous HCl solution for over 4 months. The use of different monocarboxylates as modulators leads to similar 2D structures with different layer spacings; moreover, removal of the modulator yields the parent UMCM-309a. [ABSTRACT FROM AUTHOR]

Flowing supercritical CO2 was used to activate a cross section of microporous coordination polymers (MCPs) directly from DMF, thus avoiding exchange with a volatile solvent. Most MCPs displayed exceptional surface areas directly after treatment although those with coordinatively unsaturated metals benefit from heating. The method presents an advance in efficiency of activation and quality of material obtained. [ABSTRACT FROM AUTHOR]

Flowing supercritical CO2 was used to activate a cross section of microporous coordination polymers (MCPs) directly from DMF, thus avoiding exchange with a volatile solvent. Most MCPs displayed exceptional surface areas directly after treatment although those with coordinatively unsaturated metals benefit from heating. The method presents an advance in efficiency of activation and quality of material obtained. [ABSTRACT FROM AUTHOR]

We present a planar lightwave circuit curved 2×2 coupler. Its splitting ratio has a low sensitivity to wavelength, polarization, and fabrication yet is low-loss and compact. We present simple formulae for its design. We demonstrate a 50/50 version in silica-on-silicon waveguides. We discuss the tradeoff between amplitude accuracy and phase accuracy in such densensitized couplers. [ABSTRACT FROM PUBLISHER]

A wide-tuning-range optical delay line is demonstrated in high (2%) index contrast waveguides. This device integrates four-stage ring resonator all-pass filters (APFs) with cascaded fixed spiral-type delay waveguides; each fixed delay path varies in length by a factor of two from the previous stage. A 2×2 switch separates each fixed delay and the tunable parts of the delay line. The APF allows for continuous delay tuning. This device enables coherent switching and continuous tuning ranges up to 2.56 ns. [ABSTRACT FROM PUBLISHER]

We previously demonstrated a colorless three-stage Mach-Zehnder-interferometer-type 10-Gb/s tunable dispersion compensator (TDC) in a silica-on-silicon planar lightwave circuit. However, the bandwidth was too narrow to tolerate typical transmitter wavelength drift. Here we demonstrate a wider bandwidth version, in which we increased the TDC free-spectral range (FSR) and put two TDCs in series onto the same chip. Key features are that a single voltage tunes the entire device, and a single half-wave plate makes the entire device polarization insensitive. This 50-GHz FSR device allows 180 km of 9.95-Gb/s transmission. We also demonstrate a 100-GHz FSR version, which compensates ∼±200 ps/nm of 42.7-Gb/s transmission. [ABSTRACT FROM PUBLISHER]

We previously reported a simple 10-Gb/s Mach-Zehnder-interferometer-type tunable dispersion compensator that requires only one control voltage. However, we used an expensive polarization-diversity scheme to achieve polarization independence. Here, we take advantage of the device symmetry and use a single half-wave plate to achieve low polarization sensitivity, saving significant cost and size. We demonstrate 200-km transmission of 10-Gb/s chirped nonreturn-to-zero data with only 1.8-dB path penalty. [ABSTRACT FROM PUBLISHER]

A 16-channel 100-GHz-spacing wavelength selective cross connect is demonstrated using a combination of planar waveguides and MEMS piston-mirrors. Interswitch crosstalk is eliminated and switching speed is an order of magnitude faster than typical thermooptic switches. The power consumption is smaller than one microwatt per switch. An extinction ratio of 20 dB and an insertion loss of 10.6 dB are demonstrated. [ABSTRACT FROM PUBLISHER]

The authors demonstrate an integrated add-drop filter with true reconfigurability. It can drop any combination of eight wavelengths to any of eight drop ports, with less than 7 dB loss. Its features are suitable for mass production: use of standard silica waveguide technology, double-rejection switching and filtering for all paths, compactness, and power-efficient thermooptic switching. [ABSTRACT FROM PUBLISHER]

Few hydrogen adsorbents balance high usable volumetric and gravimetric capacities. Although metal-organic frameworks (MOFs) have recently demonstrated progress in closing this gap, the large number of MOFs has hindered the identification of optimal materials. Here, a systematic assessment of published databases of real and hypothetical MOFs is presented. Nearly 500,000 compounds were screened computationally, and the most promising were assessed experimentally. Three MOFs with capacities surpassing that of IRMOF-20, the record-holder for balanced hydrogen capacity, are demonstrated: SNU-70, UMCM-9, and PCN-610/NU-100. Analysis of trends reveals the existence of a volumetric ceiling at ∼40 g H2 L−1. Surpassing this ceiling is proposed as a new capacity target for hydrogen adsorbents. Counter to earlier studies of total hydrogen uptake in MOFs, usable capacities in the highest-capacity materials are negatively correlated with density and volumetric surface area. Instead, capacity is maximized by increasing gravimetric surface area and porosity. This suggests that property/performance trends for total capacities may not translate to usable capacities. Considering the large number of existing synthesised and hypothesised metal-organic frameworks, determining which materials perform best for given applications remains a challenge. Here, the authors screen the usable hydrogen uptake capacities of nearly 500,000 MOFs, and find that three frameworks outperform the current record-holder. [ABSTRACT FROM AUTHOR]

The article presents the coordination of theno[3.2-b]thiophene-2,5-dicarboxylate (T2DC) and bromothymol blue (BTB) linkers with zinc in producing a new porous material with microporous and mesoporous cages. It notes that the University of Michigan Crystalline Material (UMCM)-2 exceeds the materials derived from the pure linkers and illustrates the highest values. It also demonstrates the highest values which suggests a very high bright future for coordination copolymerization.

The article presents a study that investigated the use of tricarboxylate with two distinct binding motifs in generating highly porous crystalline material. The linker with carboxylate groups diffused in an unsymmetrical fashion has resulted to the coordination polymer with trinuclear copper(II) clusters. The porous crystalline material called University of Michigan crystalline material (UMCM-150) containing two clusters reveals a relatively high excess volumetric and gravimetric hydrogen uptake.

The article examines the H2 saturation uptake in microporous metal-organic frameworks (MOF). The gravimetric and volumetric storage densities of H2 in MOF are approaching the limits of practical utility. Surface area values show a significant correlation with gravimetric uptake.

For WDM optical networks an N × N wavelength router with substantially reduced losses using a novel waveguide grating design is demonstrated. [ABSTRACT FROM AUTHOR]

Exploratory research into the critical steps in metal-organic framework (MOF) activation involving solvent exchange and solvent evacuation are reported. It is discovered that solvent exchange kinetics are extremely fast, and minutes rather days are appropriate for solvent exchange in many MOFs. It is also demonstrated that choice of a very low surface tension solvent is critical in successfully activating challenging MOFs. MOFs that have failed to be activated previously can achieve predicted surface areas provided that lower surface tension solvents, such as n-hexane and perfluoropentane, are applied. The insights herein aid in the efficient activation of MOFs in both laboratory and industrial settings and provide best practices for avoiding structural collapse. [ABSTRACT FROM AUTHOR]

The design, synthesis, and properties of the new microporous coordination polymer UMCM-310 are described. The unique electronic character of the perylene-based linker enables selective interaction with electron-poor aromatics leading to efficient separation of nitroaromatics. UMCM-310 possesses high surface area and large pore size and thus permits the separation of large organic molecules based on adsorption rather than size exclusion. [ABSTRACT FROM AUTHOR]

A coordination terpolymerization strategy is introduced to alter the connectivity within layers of a pillared-layer coordination polymer. Assembling two different dicarboxylate linkers around a metal cluster in the layer suppresses interpenetration while enabling formation of a rectangular 2D grid structure. [ABSTRACT FROM AUTHOR]

Design and synthesis of porous solids employing both reversible coordination chemistry and reversible covalent bond formation is described. The combination of two different linkage modes in a single material presents a link between two distinct classes of porous materials as exemplified by metal-organic frameworks (MOFs) and covalent organic frameworks (COFs). This strategy, in addition to being a compelling material-discovery method, also offers a platform for developing a fundamental understanding of the factors influencing the competing modes of assembly. We also demonstrate that even temporary formation of reversible connections between components may be leveraged to make new phases thus offering design routes to polymorphic frameworks. Moreover, this approach has the striking potential of providing a rich landscape of structurally complex materials from commercially available or readily accessible feedstocks. [ABSTRACT FROM AUTHOR]

Positronium (Ps) is shown to exist in a delocalized state in self-assembled metalorganic crystals that have large 1.3-1.5 nm cell sizes. Belonging to a class of materials with record high accessible specific surface areas, these highly porous crystals are the first to allow direct probing with simple annihilation lifetime techniques of the transport properties of long-lived triplet Ps in what is hypothesized to be a Bloch state. Delocalized Ps has unprecedented (high) Ps mobility driven primarily by weak phonon scattering with unusual and profound consequences on how Ps probes the lattice. [ABSTRACT FROM AUTHOR]

Five non-interpenetrated microporous coordination polymers (MCPs) are derived by vertex desymmetrization using linkers with symmetry inequivalent coordinating groups, and these MCPs include properties such as rare metal clusters, new network topologies, and supramolecular isomerism. Gas sorption in polymorphic frameworks, UMCM-152 and UMCM-153 (based upon a copper-coordinated tetracarboxylated triphenylbenzene linker), reveals nearly identical properties with BET surface areas in the range of 3300-3500 m2/g and excess hydrogen uptake of 5.7 and 5.8 wt % at 77 K. In contrast, adsorption of organosulfur compounds dibenzothiophene (DBT) and 4,6-dimethyldibenzothiophene (DMDBT) shows remarkably different capacities, providing direct evidence that liquid-phase adsorption is not solely dependent on surface area or linker/metal cluster identity. Structural features present in MCPs derived from these reduced symmetry linkers include the presence of more than one type of Cu-paddlewheel in a structure derived from a terphenyl tricarboxylate (UMCM-151) and a three-bladed zinc paddlewheel metal cluster in an MCP derived from a pentacarboxylated triphenylbenzene linker (UMCM-154). [ABSTRACT FROM AUTHOR]