The resource-constrained modulo scheduling problem: an experimental study

In this paper, we focus on the resource-constrained modulo scheduling problem (RCMSP), a general periodic scheduling problem, abstracted from the problem solved by compilers when optimizing inner loops at instruction level for VLIW parallel processors. Heuristic solving scheme have been proposed since many years to solve this problem, among which the decomposed software pipeling method. In this method, a cyclic scheduling problem ignoring resource constraints is first considered and a so-called legal retiming of the operations is issued. Second, a standard acyclic problem, taking this retiming as input, is solved through list scheduling techniques. In this paper, we propose a novel hybrid approach, which uses the decomposed software pipeling method to obtain a good retiming. Then the obtained retiming is used to build an integer linear programming formulation of reduced size, which allows to solve it exactly. Experimental results show that a lot more problems are solved with this new approach. The gap to the optimal solution is less than 1 % on most of the tested problem instances and the method appears to be competitive with a recently proposed constraint programming algorithm (Bonfietti et al., Lect. Notes Comput. Sci. 6876:130–144, 2011).     

A cyano-bridged bimetallic ferrimagnet: Synthesis,X-ray structure and magnetic study

Mixing of trans-[Mn(cyclam)Cl₂]Cl (cyclam = 1,4,8,11-tetraazacyclotetradecane) and potassium hexacyanochromate (K₃[Cr(CN)₆]) aqueous solutions instantaneously yields a 1D infinite chain complex {[Mn(cyclam)(μ-CN)₂Cr(CN)₄]·H₂O}_n (1). The crystal structure of 1, crystallizing in the monoclinic system with space group P2₁/n has been solved from X-ray powder diffraction data following direct space approach and refined by the Rietveld method. The structure analysis of 1 reveals alternating [Cr(CN)₆]³⁻ and [Mn(cyclam)]³⁺ ions generating one-dimensional polymeric (–Cr–CN–Mn–NC–)_n chain propagating along the [0 0 1] direction. The coordination environment of both the metal ions, Mn(III) and Cr(III), is octahedral. While a notable distortion in the coordination environment around Mn(III) centers was observed in complex 1, Cr(III) centers have suffered no such distortion. A ferrimagnetic interaction between the heterobimetallic centers was evidenced through variable temperature magnetic susceptibility measurements. The AC susceptibility measurement reveals that the compound 1 undergoes spontaneous ferrimagnetic ordering. Ferrimagnetic ordering has been rarely observed among the cyano-bridged compounds in the previous studies.     

A Switchable Catalyst Duo for Acyl Transfer Proximity Catalysis and Regulation of Substrate Selectivity

Enzymes are encoded with a gamut of information to catalyze a highly selective transformation by selecting the proper reactants from an intricate mixture of constituents. Mimicking biological machinery, two switchable catalysts with differently sized cavities and allosteric control are conceived that allow complementary size-selective acyl transfer in an on/off manner by modulating the effective local concentration of the substrates. Selective activation of one of two catalysts in a mixture of reactants of similar reactivity enabled upregulation of the desired product.     

Formation of exceptional monomeric YPhos–PdCl2 complexes with high activities in coupling reactions

The use of well-defined palladium(ii) complexes as precatalysts for C–X cross-coupling reactions has improved the use of palladium catalysts in organic synthesis including large-scale processes. Whereas sophisticated Pd(ii) precursors have been developed in the past years to facilitate catalyst activation as well as the handling of systems with more advanced monophosphine ligands, we herein report that simple PdCl₂ complexes function as efficient precatalysts for ylide-substituted phosphines (YPhos). These complexes are readily synthesized from PdCl₂ sources and form unprecedented monomeric PdCl₂ complexes without the need for any additional coligand. Instead, these structures are stabilized through a unique bonding motif, in which the YPhos ligands bind to the metal through the adjacent phosphine and ylidic carbon site. DFT calculations showed that these bonds are both dative interactions with the stronger interaction originating from the electron-rich phosphine donor. This bonding mode leads to a remarkable stability even towards air and moisture. Nonetheless, the complexes readily form monoligated LPd(0) complexes and thus the active palladium(0) species in coupling reactions. Accordingly, the YPhos–PdCl₂ complexes serve as highly efficient precatalysts for a series of C–C and C–X coupling reactions. Despite their simplicity they can compete with the efficiency of more complex and less stable precatalysts.

Ylide-substituted phosphines form monomer, air-stable PdCl₂ complexes which feature a unique bonding situation between the metal and the phosphine and ylide donor and exhibit high efficiencies as precatalysts in C–C and C–X cross-coupling reactions.     

Purification and Biochemical Characterization of a New Protease Inhibitor from Conyza dioscoridis with Antimicrobial,Antifungal and Cytotoxic Effects

The main objective of the current study was the extraction, purification, and biochemical characterization of a protein protease inhibitor from Conyza dioscoridis. Antimicrobial potential and cytotoxic effects were also examined. The protease inhibitor was extracted in 0.1 M phosphate buffer (pH 6–7). Then, the protease inhibitor, named PDInhibitor, was purified using ammonium sulfate precipitation followed by filtration through a Sephadex G-50 column and had an apparent molecular weight of 25 kDa. The N-terminal sequence of PDInhibitor showed a high level of identity with those of the Kunitz family. PDInhibitor was found to be active at pH values ranging from 5.0 to 11.0, with maximal activity at pH 9.0. It was also fully active at 50 °C and maintained 90% of its stability at over 55 °C. The thermostability of the PDInhibitor was clearly enhanced by CaCl₂ and sorbitol, whereas the presence of Ca²⁺ and Zn²⁺ ions, Sodium taurodeoxycholate (NaTDC), Sodium dodecyl sulfate (SDS), Dithiothreitol (DTT), and β-ME dramatically improved the inhibitory activity. A remarkable affinity of the protease inhibitor with available important therapeutic proteases (elastase and trypsin) was observed. PDInhibitor also acted as a potent inhibitor of commercial proteases from Aspergillus oryzae and of Proteinase K. The inhibitor displayed potent antimicrobial activity against gram+ and gram- bacteria and against fungal strains. Interestingly, PDInhibitor affected several human cancer cell lines, namely HCT-116, MDA-MB-231, and Lovo. Thus, it can be considered a potentially powerful therapeutic agent.     

Etude du fluorure de propargyle par RMN en phase nematique: Determination de la geometrie moleculaire et des signes des differentes constantes de couplage indirect

NMR spectra of proton, fluorine-19 and carbon-13 satellites of partially oriented propargyl fluoride have enabled the complete structure of this molecule to be determined. Agreement with microwave results is excellent, except for the carbon-fluorine bond length. Signs of all indirect coupling constants have been determined.     

Purification and Characterization of a Low Molecular Weight of β-Mannanase from Penicillium occitanis Pol6

The highest β-mannanase activity was produced by Penicillium occitanis Pol6 on flour of carob seed, whereas starch-containing medium gave lower enzymes titles. The low molecular weight enzyme was purified to homogeneity by ammonium sulfate precipitation, gel filtration, and ion-exchange chromatography procedures. The purified β-mannanase (ManIII) has been identified as a glycoprotein (carbohydrate content 5%) with an apparent molecular mass of 18 kDa. It was active at 40 °C and pH 4.0. It was stable for 30 min at 70 °C and has a broad pH stability (2.0–12.0). ManIII showed K _m, V _max, and K _cat values of 17.94 mg/ml, 93.52 U/mg, and 28.13 s⁻¹ with locust bean gum as substrate, respectively. It was inhibited by mannose with a K _I of 0.610⁻³ mg/ml. ManIII was activated by CuSO₄ and CaCl₂ (2.5 mM). However, in presence of 2.5 mM Co²⁺, its activity dropped to 60% of the initial activity. Both N-terminal and internal amino acid sequences of ManIII presented no homology with mannanases of glycosides hydrolases. During incubation with locust bean gum and Ivory nut mannan, the enzyme released mainly mannotetraose, mannotriose, and mannobiose.     

Entanglement of a quantum optical elliptic vortex

We calculate the entanglement of a generalized elliptical vortex formed by quantized radiation field, using Wigner quasiprobability distribution function for such states. We find a critical squeezing parameter above which the entanglement is less for higher vorticity, which is counter intuitive.     

Crystallization-in-emulsion process of a melted organic compound: In situ optical monitoring and simultaneous droplet and particle size measurements

The crystallization-in-emulsion process allows the production of solid particles exhibiting specific features. Here, the batch crystallization process carried out by cooling a melted oil dispersed as an oil-in-water emulsion was studied. Two experimental set-ups allowing the in situ visualization of the nucleation and growth phenomena occurring in the dispersed liquid phase were developed. Observations in quiescent medium of motionless droplets having a diameter of few tens of micrometers showed that primary nucleation started on the inner surface of the droplets. The fast growth of the crystals consumed all the liquid contained within each droplet and was confined within each droplet by the oil–water interface. Solid polycrystalline particles similar in size to the parent droplets were produced. Dynamic tracking of the transient evolution of the size distributions of the two populations of droplets and solid particles during the cooling process in a stirred vessel was carried out using an in situ optical probe. It was shown that the droplets crystallized very progressively during cooling, starting with the largest droplets and ending with the smaller size droplets since the induction time of primary nucleation was dependent on droplet volume. In dilute conditions (1% wt% of dispersed phase) each droplet was converted into a single solid particle. Secondary nucleation based on inter-droplet collisions was not observed in these conditions.     

Structure du propyne par RMN en phase nématique. Utilisation des satellites du carbone-13

The proton NMR spectrum and carbon-13 satellites of partially oriented propyne give the complete structure of this molecule. Agreement with microwave results is excellent.