Gravitational radiation from inspiralling compact binaries completed at the third post-Newtonian order

The gravitational radiation from point particle binaries is computed at the third post-Newtonian (3PN) approximation of general relativity. Three previously introduced ambiguity parameters, coming from the Hadamard self-field regularization of the 3PN source-type mass quadrupole moment, are consistently determined by means of dimensional regularization, and proved to have the values xi=-9871/9240, kappa=0, and zeta=-7/33. These results complete the derivation of the general relativistic prediction for compact binary inspiral up to 3.5PN order, and should be of use for searching and deciphering the signals in the current network of gravitational wave detectors.     

Specific interactions of complementary mono- and multivalent guests with recognition-induced polymersomes

We have explored the interactions of mono- and multivalent guests with Recognition-Induced Polymersomes (RIPs) formed from complementary random copolymers featuring diamidopyridine and thymine functionality. Addition of monovalent guests featuring imide functionality to these RIPs induced a temporary swelling of the vesicles, followed by dissociation of the vesicles due to competitive binding of the guest. Conversely, multivalent thymine-functionalized nanoparticle guests were rapidly incorporated into the RIPs, inducing a contraction of RIP diameter over time. These mono- and multivalent interactions were extremely specific: highly analogous control systems showed no interaction with the RIP structures. Taken together, these studies demonstrate highly selective molecular "lock and key" control over higher-order assembly and recognition processes.     

Geometrical interpretation of acoustic holography: Adaptation of the propagator and minimum quality guaranteed in the presence of errors

A large number of inverse problems in acoustics consist of a reverse propagation of the acoustic pressure measured with an array of microphones. The goal is usually to identify the acoustic source location and strength or the surface velocity of a vibrating structure. The quality of the results obtained depends on the propagation model, on the accuracy of the pressure measurements and, finally, on the inverse problem conditioning. How to quantify this quality is the issue addressed in this paper. For this purpose, a geometrical interpretation of the inverse acoustic problem is proposed. The main application will, eventually, be near-field acoustic holography (NAH), but it is expected that the proposed approach will also apply to other types of inverse acoustic problems. First, the geometrical representation of the inverse problem is proposed. The inverse problem is stated from a direct linear problem in the frequency domain. For each frequency, an overdetermined system of linear complex algebraic equations must be inverted. The concept of quality is discussed and a quality index is proposed based upon the residue of the inverse problem, solved in a mean square sense. Then, a simple one-dimensional (plane wave) acoustic example consisting of a source and two pressure measurements is used to illustrate the proposed geometrical representation of the inverse problem and the quality criterion inspired by it. In the simple example, the propagation model can be improved by searching for a reflection coefficient at the origin of the simulated hologram. This reflection coefficient is used to simulate the presence of a hidden source placed behind the source. An artificial attenuation is introduced to simulate the effect of geometrical attenuation present in real NAH problems. Again, using the geometrical representation, it is shown how, from an improved propagation model together with a given measurement noise level in the hologram, one can guarantee a certain quality level of the inverse procedure. Finally, numerical results show, in a preliminary way, how the identified source strength converges towards the exact velocity when the estimated propagation model tends to the exact propagation model.     

A Cramér–Rao inequality for non-differentiable models

We compute a variance lower bound for unbiased estimators in statistical models. The construction of the bound is related to the original Cramér–Rao bound, although it does not require the differentiability of the model. Moreover, we show our efficiency bound to be always greater than the Cramér–Rao bound in smooth models, thus providing a sharper result.     

CO2 Conversion into Esters by Fluoride‐Mediated Carboxylation of Organosilanes and Halide Derivatives

A one‐step conversion of CO₂ into heteroaromatic esters is presented under metal‐free conditions. Using fluoride anions as promoters for the C?Si bond activation, pyridyl, furanyl, and thienyl organosilanes are successfully carboxylated with CO₂ in the presence of an electrophile. The mechanism of this unprecedented reaction has been elucidated based on experimental and computational results, which show a unique catalytic influence of CO₂ in the C?Si bond activation of pyridylsilanes. The methodology is applied to 18 different esters, and it has enabled the incorporation of CO₂ into a polyester material for the first time.     

Reductive Coupling of Diynes at Rhodium Gives Fluorescent Rhodacyclopentadienes or Phosphorescent Rhodium 2,2’‐Biphenyl Complexes

Reactions of [Rh(κ²‐O,O‐acac)(PMe₃)₂] (acac=acetylacetonato) and α,ω‐bis(arylbutadiynyl)alkanes afford two isomeric types of MC₄ metallacycles with very different photophysical properties. As a result of a [2+2] reductive coupling at Rh, 2,5‐bis(arylethynyl)rhodacyclopentadienes ( A ) are formed, which display intense fluorescence (Φ=0.07–0.54, τ=0.2–2.5 ns) despite the presence of the heavy metal atom. Rhodium biphenyl complexes ( B ), which show exceptionally long‐lived (hundreds of μs) phosphorescence (Φ=0.01–0.33) at room temperature in solution, have been isolated as a second isomer originating from an unusual [4+2] cycloaddition reaction and a subsequent β‐H‐shift. We attribute the different photophysical properties of isomers A and B to a higher excited state density and a less stabilized T₁ state in the biphenyl complexes B , allowing for more efficient intersystem crossing S₁→T_n and T₁→S₀. Control of the isomer distribution is achieved by modification of the bis‐ (diyne) linker length, providing a fundamentally new route to access photoactive metal biphenyl compounds.     

Synthesis of double hydrophilic poly(ethylene oxide)‐b‐poly(2‐hydroxyethyl acrylate) by single‐electron transfer–living radical polymerization

In this study, the polymerization of (2‐hydroxyethyl) acrylate (HEA), in polar media, using Cu(0)‐mediated radical polymerization also called single‐electron transfer–living radical polymerization (SET‐LRP) is reported. The kinetics aspects of both the homopolymerization and the copolymerization from a poly(ethylene oxide) (PEO) macroinitiator were analyzed by ¹H NMR. The effects of both the ligand and the solvent were studied. The polymerization was shown to reach very high monomer conversions and to proceed in a well‐controlled fashion in the presence of tris[2‐(dimethylamino)ethyl]amine Me6‐TREN and N, N,N′, N″, N″‐pentamethyldiethylenetriamine (PMDETA) in dimethylsulfoxide (DMSO). SET‐LRP of HEA was also led in water, and it was shown to be faster than in DMSO. In pure water, Me₆‐TREN allowed a better control over the molar masses and polydispersity indices than PMDETA and TREN. Double hydrophilic PEO‐b‐PHEA block copolymers, exhibiting various PHEA block lengths up to 100 HEA units, were synthesized, in the same manner, from a bromide‐terminated PEO macroinitiator. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Dextran-coated silica nanoparticles for calcium-sensing

This article describes the synthesis and characterisation of fluorescent composite nanoparticles consisting of a silica core and a dextran shell. The silica core contains a rhodamine-based reference dye, which allows ratiometric measurements and the dextran shell is labelled with the Ca(2+)-sensitive dye Fluo-4. The nanoparticles have an average hydrodynamic diameter of 95 nm, good colloidal stability and show a 2.9-fold increase in fluorescence intensity upon binding to Ca(2+) ions. The apparent dissociation constant of K'(d) ≈ 520 nM is well suited for measurements in the physiological range.     

Adsorbent screening for biobutanol separation by adsorption: kinetics, isotherms and competitive effect of other compounds

Butanol, considered as one of the best renewable alternatives for gasoline, has attracted significant attention in recent years. However, biobutanol production via fermentation is plagued by the low final product concentration due to product inhibition. It is possible to enhance productivity by selectively removing biobutanol from the fermentation broth. Adsorption is one of the most promising and energy-efficient techniques for butanol separation and recovery. In the present study, different adsorbents were tested by performing kinetic and equilibrium experiments to find the best adsorbent for butanol separation. Activated carbon (AC) F-400 showed the fastest adsorption rate and the highest adsorption capacity amongst ACs and zeolites tested. AC F-400 also showed the highest affinity toward butanol and to a lesser extent for butyric acid whereas its adsorption capacity for the other main components present in acetone–butanol–ethanol fermentation broths was very low. In addition, the butanol adsorption capacity was not affected by the presence of ethanol, glucose and xylose while the presence of acetone led to a slight decrease in adsorption capacity at low butanol concentrations. On the other hand, the presence of acids (acetic acid and butyric acid) showed a significant effect on the butanol adsorption capacity over a wide range of butanol concentration and this effect was more pronounced for butyric acid.