Scheduling two agents with controllable processing times

We consider several two-agent scheduling problems with controllable job processing times, where agents A and B have to share either a single machine or two identical machines in parallel while processing their jobs. The processing times of the jobs of agent A are compressible at additional cost. The objective function for agent B is always the same, namely a regular function _fmax$f_{\text{max}}$. Several different objective functions are considered for agent A, including the total completion time plus compression cost, the maximum tardiness plus compression cost, the maximum lateness plus compression cost and the total compression cost subject to deadline constraints (the imprecise computation model). All problems are to minimize the objective function of agent A subject to a given upper bound on the objective function of agent B. These problems have various applications in computer systems as well as in operations management. We provide NP-hardness proofs for the more general problems and polynomial-time algorithms for several special cases of the problems.     

A chiral pool approach to the synthesis of optically active tetrahalo norbornyl building blocks

Optical antipodes of the mono- and disubstituted polyhalo norbornyl derivatives were prepared in excellent yields. The monosubstituted derivatives 7 were obtained with good enantiopurities. A kaleidoscopic change in the product formation and distribution was observed by changing the chronology of reactions.     

Synthesis of a new class of spiro heterocycles

A new class of spiro heterocycles viz., spiropyrazolidinediones, isoxazolidinediones, pyrimidinetriones or thioxopyrimidinediones are developed from methyl 3‐aryl‐2‐(Z‐arylethenenylsulfonyl)acrylate by double Michael addition reaction with dimethyl malonate followed by cyclocondensation with appropriate nucleophiles.     

Effect of substrate temperature on structural, optical and electrical properties of pulsed laser ablated nanostructured indium oxide films

Nanocrystalline indium oxide (INO) films are deposited in a back ground oxygen pressure at 0.02 mbar on quartz substrates at different substrate temperatures (T_s) ranging from 300 to 573 K using pulsed laser deposition technique. The films are characterized using GIXRD, XPS, AFM and UV-visible spectroscopy to study the effect of substrate temperature on the structural and optical properties of films. The XRD patterns suggest that the films deposited at room temperature are amorphous in nature and the crystalline nature of the films increases with increase in substrate temperature. Films prepared at T_s ≥ 473 K are polycrystalline in nature (cubic phase). Crystalline grain size calculation based on Debye Scherrer formula indicates that the particle size enhances with the increase in substrate temperature. Lattice constant of the films are calculated from the XRD data. XPS studies suggest that all the INO films consist of both crystalline and amorphous phases. XPS results show an increase in oxygen content with increase in substrate temperature and reveals that the films deposited at higher substrate temperatures exhibit better stoichiometry. The thickness measurements using interferometric techniques show that the film thickness decreases with increase in substrate temperature. Analysis of the optical transmittance data of the films shows a blue shift in the values of optical band gap energy for the films compared to that of the bulk material owing to the quantum confinement effect due to the presence of quantum dots in the films. Refractive index and porosity of the films are also investigated. Room temperature DC electrical measurements shows that the INO films investigated are having relatively high electrical resistivity in the range of 0.80-1.90 Ωm. Low temperature electrical conductivity measurements in the temperature range of 50-300 K for the film deposited at 300 K give a linear Arrhenius plot suggesting thermally activated conduction. Surface morphology studies of the films using AFM reveal the formation of nanostructured indium oxide thin films.     

Early detection of insulin fibrillation: a fluorescence lifetime assay to probe the pre-fibrillar regime

Using human insulin, we report for the first time, the evaluation of fluorescence lifetime of an extrinsically added fluorogenic dye, Thioflavin T (ThT), as a more sensitive and convenient method for the assessment of fibrillation in the pre-fibrillar regime.     

Aziridination Reactivity of a Manganese(II) Complex with a Bulky Chelating Bis(Alkoxide) Ligand

Treatment of Mn(N(SiMe₃)₂)₂(THF)₂ with bulky chelating bis(alkoxide) ligand [1,1′:4′,1′′-terphenyl]-2,2′′-diylbis(diphenylmethanol) (H₂[O-terphenyl-O]^Ph) formed a seesaw manganese(II) complex Mn[O-terphenyl-O]^Ph(THF)₂, characterized by structural, spectroscopic, magnetic, and analytical methods. The reactivity of Mn[O-terphenyl-O]^Ph(THF)₂ with various nitrene precursors was investigated. No reaction was observed between Mn[O-terphenyl-O]^Ph(THF)₂ and aryl azides. In contrast, the treatment of Mn[O-terphenyl-O]^Ph(THF)₂ with iminoiodinane PhINTs (Ts = p-toluenesulfonyl) was consistent with the formation of a metal-nitrene complex. In the presence of styrene, the reaction led to the formation of aziridine. Combining varying ratios of styrene and PhINTs in different solvents with 10 mol% of Mn[O-terphenyl-O]^Ph(THF)₂ at room temperature produced 2-phenylaziridine in up to a 79% yield. Exploration of the reactivity of Mn[O-terphenyl-O]^Ph(THF)₂ with various olefins revealed (1) moderate aziridination yields for p-substituted styrenes, irrespective of the electronic nature of the substituent; (2) moderate yield for 1,1′-disubstituted α-methylstyrene; (3) no aziridination for aliphatic α-olefins; (4) complex product mixtures for the β-substituted styrenes. DFT calculations suggest that iminoiodinane is oxidatively added upon binding to Mn, and the resulting formal imido intermediate has a high-spin Mn(III) center antiferromagnetically coupled to an imidyl radical. This imidyl radical reacts with styrene to form a sextet intermediate that readily reductively eliminates the formation of a sextet Mn(II) aziridine complex.     

Bio-based tri-functional epoxy resin (TEIA) blend cured with anhydride (MHHPA) based cross-linker: Thermal,mechanical and morphological characterization

A novel renewable resource based tri-functional epoxy resin from itaconic acid (TEIA) was blended with petroleum based epoxy resin (DGEBA) and fabricated at different ratios. Then, it was by thermally cured with methylhexahydrophthalic anhydride (MHHPA) in presence of 2-methylimidazole (2-MI) catalyst. The tensile, modulus, strength of virgin epoxy resin (41.97 MPa, 2222 MPa) increased to 47.59 MPa, 2515 MPa, respectively, with the addition of 30% of TEIA. The fracture toughness parameter, critical stress intensity factor (K_IC) revealed enhancement of toughness in the TEIA bio-based blends system. The thermomechanical properties of TEIA (tri-functional epoxy resin from itaconic acid) modified petroleum-epoxy networks were investigated by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and dynamic mechanical analysis (DMA). The fracture morphology was also studied by the scanning electron microscopy and atomic force microscopy respectively.     

Chemoselective reduction of aromatic nitro and azo compounds in ionic liquids using zinc and ammonium salts

Nitroarenes were chemoselectively reduced to the corresponding amines using zinc and aqueous ammonium salts in ionic liquids as a safe and recyclable reaction medium. Our results specify the effect of ammonium salts in the process; the combination of Zn/NH₄Cl in [bmim][PF₆] or Zn/HCO₂NH₄ in [bmim][BF₄] were the suitable conditions for the reduction of nitroarenes. Azobenzenes were also smoothly reduced to hydrazobenzenes with Zn/HCO₂NH₄ (aq.) in recyclable [bmim][BF₄] without any over reduction to the corresponding anilines.     

Synthesis of a novel, highly symmetric bis-oxa-bridged compound

A highly oxygenated, novel pentacyclic bis-oxa-bridged compound 8 was synthesized with remarkable efficiency starting from readily available tetrachloro-5,5-dimethoxyclopentadiene and 1,4-cyclohexadiene in three steps. The ruthenium-catalyzed oxidation of 2:1 bis-adduct 1 followed by a one-pot transformation of the resulting bis-alpha-diketone 3 furnished (after esterification) the title compound in an overall yield of 29.1%. The versatility of this simple method was further demonstrated with other norbornyl alpha-diketones to obtain the corresponding strained oxa-bridged derivatives.