Measurement and analysis of the ν2 bands of 14ND3 and 15ND3

The ν₂ fundamentals of ¹⁴ND₃ and ¹⁵ND₃ have been observed with sufficient resolution to resolve many of the individual P, Q, and R lines for both components of the inversion doublet. With the help of the observed intensity alterations assignments of many of the lines were made. A least-squares analysis was applied to determine the various vibration-rotation constants pertinent for these transitions. The ¹⁴N¹⁵N isotope shift is found to be ?6.2 cm^?1.     

The real gauge hierarchy problem

We discuss the problem of generating two vastly different mass scales through spontaneous symmetry breaking. We find that to all orders in perturbation theory this can only be achieved if there is a non-trivial relation between the couplings of the theory. While this relation may come from a higher symmetry we find that this symmetry can only be broken at the low mass scale.     

On the determination of sin2θw in semileptonic neutrino interactions

It is shown that if sin²θ_w is measured in semileptonic neutrino interactions then, contrary to a claim in the literature, the error due to unknown dynamical (higher-twist) corrections to the QCD parton model is small provided an isoscalar target is used. The largest contributions to σ_nc and σ_cc are related by isospin invariance alone. Neglecting heavy quarks and Kobayashi-Maskawa (KM) mixing, the parton model is only needed for very small terms and introduces an uncertainty in sin²θ_w which is probably less than 1%. There is a much larger theoretical error due to uncertainties in the element U_cs of the KM matrix and in the strange quark distribution. With the full range 0.80 ? | U_cs | 0.98 which is allowed phenomenologically, these uncetainties give δsin²θ_w = ± 0.008. There is also an error of ±0.004 due to uncertainties in |U_dc| and |U_du|.     

Vortex pairs and dipoles

Point vortices have been extensively studied in vortex dynamics. The generalization to higher singularities, starting with vortex dipoles, is not so well understood.We obtain a family of equations of motion for inviscid vortex dipoles and discuss limitations of the concept. We then investigate viscous vortex dipoles, using two different formulations to obtain their propagation velocity. We also derive an integro-differential for the motion of a viscous vortex dipole parallel to a straight boundary.     

Tuning the Properties of MOF-808 via Defect Engineering and Metal Nanoparticle Encapsulation

Defect engineering and metal encapsulation are considered as valuable approaches to fine-tune the reactivity of metal–organic frameworks. In this work, various MOF-808 (Zr) samples are synthesized and characterized with the final aim to understand how defects and/or platinum nanoparticle encapsulation act on the intrinsic and reactive properties of these MOFs. The reactivity of the pristine, defective and Pt encapsulated MOF-808 is quantified with water adsorption and CO₂ adsorption calorimetry. The results reveal strong competitive effects between crystal morphology and missing linker defects which in turn affect the crystal morphology, porosity, stability, and reactivity. In spite of leading to a loss in porosity, the introduction of defects (missing linkers or Pt nanoparticles) is beneficial to the stability of the MOF-808 towards water and could also be advantageously used to tune adsorption properties of this MOF family.     

Comparison of the biological properties of several marine sponge-derived sesquiterpenoid quinones

Eight naturally occurring marine-sponge derived sesquiterpenoid quinones were evaluated as potential inhibitors of pyruvate phosphate dikinase (PPDK), a C4 plant regulatory enzyme. Of these, the hydroxyquinones ilimaquinone, ethylsmenoquinone and smenoquinone inhibited PPDK activity with IC50's (reported with 95% confidence intervals) of 285.4 (256.4-317.7), 316.2 (279.2-358.1) and 556.0 (505.9-611.0) microM, respectively, as well as being phytotoxic to the C4 plant Digitaria ciliaris. The potential anti-inflammatory activity of these compounds, using bee venom phospholipase A2 (PLA2), was also evaluated. Ethylsmenoquinone, smenospongiarine, smenospongidine and ilimaquinone inhibited PLA2 activity (% inhibition of 73.2 +/- 4.8 at 269 microM, 61.5 +/- 6.1 at 242 microM, 41.0 +/- 0.6 at 224 microM and 36.4 +/- 8.2 at 279 microM, respectively). SAR analyses indicate that a hydroxyquinone functionality and a short, hydroxide/alkoxide side-chain atC-20 is preferred for inhibition of PPDK activity, and that a larger amine side-chain at C-20 is tolerated for PLA2 inhibitory activity.     

An Evaluation of UiO‐66 for Gas‐Based Applications

In addition to its high thermal stability, repetitive hydration/dehydration tests have revealed that the porous zirconium terephthalate UiO‐66 switches reversibly between its dehydroxylated and hydroxylated versions. The structure of its dehydroxylated form has thus been elucidated by coupling molecular simulations and X‐ray powder diffraction data. Infrared measurements have shown that relatively weak acid sites are available while microcalorimetry combined with Monte Carlo simulations emphasize moderate interactions between the UiO‐66 surface and a wide range of guest molecules including CH₄, CO, and CO₂. These properties, in conjunction with its significant adsorption capacity, make UiO‐66 of interest for its further evaluation for CO₂ recovery in industrial applications. This global approach suggests a strategy for the evaluation of metal–organic frameworks for gas‐based applications.     

Why hybrid porous solids capture greenhouse gases?

Hybrid porous solids, with their tunable structures, their multifunctional properties and their numerous applications, are currently topical, particularly in the domain of adsorption and storage of greenhouse gases. Most of the data reported so far concern the performances of these solids in this domain, particularly in terms of adsorbed amounts of gas but do not explain at the atomic level why and how adsorption and storage occur. From a combination of structural, spectroscopic, thermodynamic experiments and of molecular simulations, this tutorial review proposes answers to these open questions with a special emphasis on CO(2) and CH(4) storage by some rigid and flexible hybrid porous materials.     

High uptakes of CO2 and CH4 in mesoporous metal-organic frameworks MIL-100 and MIL-101

Mesoporous MOFs MIL-100 and MIL-101 adsorb huge amounts of CO2 and CH4. Characterization was performed using both manometry and gravimetry in different laboratories for isotherms coupled with microcalorimetry and FTIR to specify the gas-solid interactions. In particular, the uptake of carbon dioxide in MIL-101 has been shown to occur with a record capacity of 40 mmol g(-1) or 390 cm3STP cm(-3) at 5 MPa and 303 K.