Bis(metallo) Capsules Based on Two Ionic Diphosphines

Self‐assembly and characterization of heterodimeric diphosphine capsules formed by multiple ionic interactions are described. The first type of capsules is composed of one novel tetrasulfonato‐xantphos ligand and one complementary tetraammonium calix[4]arene. Encapsulation of a transition metal is achieved by self‐assembly of a rhodium complex containing the tetraanionic diphosphine ligand and a tetracationic calix[4]arene. The second type of capsules is composed of two oppositely charged diphosphine ligands: one tetrasulfonato‐xantphos and one tetraammonium‐diphosphine (of the xantphos‐, DPEphos‐, and 1,2‐bis(diphenylphosphino)ethane (dppe)‐type). Bis(metallo) capsules, that is, simultaneous encapsulation of two different transition metals, are created by self‐assembly of a palladium or platinum complex containing a tetracationic ligand and a rhodium complex containing a tetraanionic ligand. Diphosphine ligands with different flexibilities and shapes assemble into metallocapsules with a proper capsular structure, as is indicated by ¹H NMR and 1D‐NOESY spectroscopy, ESIMS, and modeling studies.     

Identification of acyl protein thioesterases 1 and 2 as the cellular targets of the ras-signaling modulators palmostatin b and m

Finding the target: Activity-based proteomic profiling probes based on the depalmitoylation inhibitors palmostatin?B and M have been synthesized and were found to target acyl protein thioesterase?1 (APT1) and 2 (APT2) in cells.     

Thermal and rheological properties of a family of botryosphaerans produced by Botryosphaeria rhodina MAMB-05

Differential scanning calorimetry (DSC), thermogravimetry (TG) and Fourier-transform infra-red spectroscopy (FT-IR) analyses were performed to investigate changes in the physico-chemical properties of botryosphaerans, a family of exopolysaccharides (EPS) produced by the fungus Botryosphaeria rhodina MAMB-05 grown on glucose (EPS(GLC)), sucrose (EPS(SUC)) and fructose (EPS(FRU)). A slight endothermic transition and small mass loss attributable to the removal of water of hydration were observed in the DSC and TG analyses, respectively, for the three EPS samples. The FT-IR spectra confirmed no structural changes occurred during thermal treatment. Viscometry was utilized to obtain information on the rheological behaviour of the EPS in aqueous solutions. The Power Law and Cross Equations determined the natural pseudoplastic characteristics of the EPS. Comparatively, results obtained for EPS produced when B. rhodina MAMB-05 was grown on each of the three carbohydrate sources demonstrated similar apparent viscosity values for EPS(GLC) and EPS(SUC), while EPS(FRU) displayed the lowest apparent viscosity of the three botryosphaerans, suggesting a higher degree of ramification and lower Mw. EPS(GLC) and EPS(SUC) possessed similar degrees of ramification. The slight differences found in their viscosities can be explained by the differences in the type of branching among the three botryosphaerans, thus varying the strength of intermolecular interactions and consequently, consistency and viscosity. The physico-chemical studies of botryosphaerans represent the originality of this work, and the knowledge of these properties is an important criterion for potential applications.     

Octave spanning supercontinuum in an As₂S₃ taper using ultralow pump pulse energy

An octave spanning spectrum is generated in an As?S? taper via 77 pJ pulses from an ultrafast fiber laser. Using a previously developed tapering method, we construct a 1.3 μm taper that has a zero-dispersion wavelength around 1.4 μm. The low two-photon absorption of sulfide-based chalcogenide fiber allows for higher input powers than previous efforts in selenium-based chalcogenide tapered fibers. This higher power handling capability combined with input pulse chirp compensation allows an octave spanning spectrum to be generated directly from the taper using the unamplified laser output.     

Methods for strategic liner shipping network design

In this paper the combined fleet-design, ship-scheduling and cargo-routing problem with limited availability of ships in liner shipping is considered. A composite solution approach is proposed in which the ports are first aggregated into port clusters to reduce the problem size. When the cargo flows are disaggregated, a feeder service network is introduced to ship the cargo within a port cluster. The solution method is tested on a problem instance containing 58 ports on the Asia–Europe trade lane of Maersk. The best obtained profit gives an improvement of more than 10% compared to the reference network based on the Maersk network.     

Rational Design in Photopharmacology with Molecular Photoswitches

Photopharmacology is an attractive approach for achieving targeted drug action with the use of light. In photopharmacology, molecular photoswitches are introduced into the structure of biologically active small molecules to allow for the optical control of their potency. Going beyond trial and error, photopharmacology has progressively applied rational drug design methodologies to devise light-controlled bioactive ligands. In this review, we categorize photopharmacological efforts from the standpoint of medicinal chemistry strategies, focusing on diffusible photochromic ligands modified with photoswitches that operate through E-Z bond isomerization. In the vast majority of cases, photoswitchable ligands are designed as analogs of existing compounds, through a variety of approaches. By analyzing in detail a comprehensive list of instructive examples, we describe the state of the art and discuss future opportunities for rational design in photopharmacology.     

Tunneling in suspended carbon nanotubes assisted by longitudinal phonons

Current-voltage characteristics of suspended single-wall carbon nanotube quantum dots show a series of steps equally spaced in voltage. The energy scale of this harmonic, low-energy excitation spectrum is consistent with that of the longitudinal low-k phonon mode (stretching mode) in the nanotube. Agreement is found with a Franck-Condon-based model in which the phonon-assisted tunneling process is modeled as a coupling of electronic levels to underdamped quantum harmonic oscillators. A comparison with this model indicates a rather strong electron-phonon coupling factor of order unity.     

Vibrational resonances of nonrigid vehicles: Polygonization and ripple patterns

The well-known phenomenon of ripples on roads has its modern counterpart in ripple patterns on railroads and polygonization of wheels on state-of-the-art lightrail streetcars. Here we study an idealized mechanical suspension model for the vibrational frequency response of a buggy with a nonrigid body (typically, an aluminium chassis and coach). The finite flexural rigidity of the body is an important novel feature. Since the essential physics is described by only one extra material parameter (viz. the stiffness coefficient), the model retains its basic simplicity and can still be analysed exactly. The dynamics (i.e., the Lagrangian equations of motion) are solved in the frequency domain. The motion on a distorted surface is treated as a nonholonomic constraint. Thus we analytically calculate spectra, e.g., the wheel spectrum. This reveals a new, significant wheel resonance (typically near 30–35 Hz), which is confirmed by means of a novel analysis of the wheel’s lift force (taking care of traction forces). At moderate city speeds this resonance agrees with recently observed characteristic ripple patterns on lightrail tracks, with wavelengths of approximately 10–20 cm (amplitudes of the order of a millimeter), and correspondingly polygonized wheels.