Grouping Techniques for Scheduling Problems: Simpler and Faster

In this paper we describe a general grouping technique to devise faster and simpler approximation schemes for several scheduling problems. We illustrate the technique on two different scheduling problems: scheduling on unrelated parallel machines with costs and the job shop scheduling problem. The time complexity of the resulting approximation schemes is always linear in the number n of jobs, and the multiplicative constant hidden in the O(n) running time is reasonably small and independent of the error ε. Supported by Swiss National Science Foundation project 200020-109854, “Approximation Algorithms for Machine scheduling Through Theory and Experiments II”. A preliminary version of this paper appeared in the Proceedings of ESA’01.     

New 2,2-difluoro-1,3,2(2H)oxazaborines and merocyanines derived from them

Synthetic methods have been developed to prepare oxazaborines, the azaanalogues of 2,2-difluoro-1,3,2(2H)dioxaborines, which can form merocyanine dyes. The first oxazaborine merocyanines with the isomeric position of the coordinating nitrogen atom have also been obtained. Comparing the spectral properties of donor-acceptor dioxa- and oxazaborine dyes, it is seen that substitution of the 3-O atom by the NH group in the chelate ring has a slight effect on absorption and fluorescence band positions but causes the intensity redistribution between the 0-0 and 0-1 vibronic absorption peaks and thus induces a change in the absorption band shape due to the enhanced solvation of oxazaborines. Substitution of the 1-O ring atom by the NPh group leads to a bathochromic shift and a manifold increase in the fluorescence quantum yield for the corresponding boron chelate dyes.     

NEXAFS study of electronic and atomic structure of active layer in Al/indium tin oxide/TiO2 stack during resistive switching

We have studied the stability of the resistive switching process in the Al/(In₂O₃)_0.9(SnO₂)_0.1/TiO₂ assembly grown by atomic layer deposition. Besides electrical characterization the effect of electric field on the atomic electronic structure of the TiO₂ layer was studied using near edge X-ray absorption fine structure (NEXAFS) spectroscopy. The region of the current instability in the I-V characteristics was revealed. Presumably this current instability is supported by the amorphous structure of the TiO₂ film but is initiated by the surface morphology of the Al substrate. A formation of the O₂ molecules was established which occurs specifically in the region of the current instability that is a result of electrical Joule heating manifestation.     

The first ribbed functionalized tris-dioximate clathrochelates with inherent hydroxyl substituents: Synthesis, spectra and X-ray structure

The controlled hydrolysis of the dichlorine-containing iron(II) clathrochelate FeBd₂(Cl₂Gm)(BF)₂ precursor (where Bd²⁻ and Cl₂Gm²⁻ are α-benzyldioxime and dichloroglyoxime dianions, respectively) afforded the hydroxy-containing clathrochelate derivatives with the hydroxyl substituent inherently bound to the ribbed chelate fragment of the macrobicyclic ligand. The triethylammonium and tetra-n-butylammonium salts of the clathrochelate [FeBd₂(OClGm)(BF)₂]⁻ anion have been characterized using elemental analysis, MALDI-TOF mass spectrometry, IR, UV–Vis, ⁵⁷Fe Mössbauer and ¹H, ¹³C{¹H}, ¹¹B and ¹⁹F NMR spectroscopies, and X-ray crystallography. The X-ray structural data for this deprotonated anion showed strong delocalization of its negative charge into the clathrochelate framework.     

Development of the Fray-Farthing-Chen Cambridge Process: Towards the Sustainable Production of Titanium and Its Alloys

The Kroll process has been employed for titanium extraction since the 1950s. It is a labour and energy intensive multi-step semi-batch process. The post-extraction processes for making the raw titanium into alloys and products are also excessive, including multiple remelting steps. Invented in the late 1990s, the Fray-Farthing-Chen (FFC) Cambridge process extracts titanium from solid oxides at lower energy consumption via electrochemical reduction in molten salts. Its ability to produce alloys and powders, while retaining the cathode shape also promises energy and material efficient manufacturing. Focusing on titanium and its alloys, this article reviews the recent development of the FFC-Cambridge process in two aspects, (1) resource and process sustainability and (2) advanced post-extraction processing.     

Serendipitous Identification of a Covalent Activator of Liver Pyruvate Kinase

Enzymes are effective biological catalysts that accelerate almost all metabolic reactions in living organisms. Synthetic modulators of enzymes are useful tools for the study of enzymatic reactions and can provide starting points for the design of new drugs. Here, we report on the discovery of a class of biologically active compounds that covalently modifies lysine residues in human liver pyruvate kinase (PKL), leading to allosteric activation of the enzyme (EC₅₀=0.29 μM). Surprisingly, the allosteric activation control point resides on the lysine residue K282 present in the catalytic site of PKL. These findings were confirmed by structural data, MS/MS experiments, and molecular modelling studies. Altogether, our study provides a molecular basis for the activation mechanism and establishes a framework for further development of human liver pyruvate kinase covalent activators.