Optical response of Lorentzian nanospheres in the quasistatic limit

Significance of the Lorentzian dispersion relationship in controlling the optical response of the nanospheres surrounded by a homogeneous non-absorbing dielectric medium is examined. Nanospheres with size much smaller than the wavelength of the incident light are considered as prototype systems that can cover the generic optical response of Lorentzian nanoparticles. Absorption cross-section of the Lorentzian nanospheres is treated in the quasistatic approximation of classical electrodynamics and the resulting optical resonance is evaluated in terms of its dependencies on the parameters of the system. It has been illustrated that the underlying dispersion governs both the amount and the direction of the shift experienced by the optical resonance of nanospheres. Contrary to Drude nanospheres (well-known red shifters), Lorentzian nanospheres are shown to be blue shifters of the optical resonance. The amount of blue shift is dominated by the increase in the oscillator strength of the nanosphere material. Embedding media with higher dielectric constant and/or materials with larger high frequency dielectric constant lead to a suppression of the amount of blue shift induced by the oscillator strength. Further quantification of the blue shift characteristics against the red shift characteristics of Drude nanospheres is provided. The results can be instrumental for manipulating the optical response of plexcitonic nanophotonic devices.     

Photophysical properties of PPP and PPV derivatives bearing polystyrene or polycaprolactone as side groups

This contribution reports on detailed photophysical investigations of poly(p-phenylene) PPP and poly(p-phenylene-vinylene) (PPV) derivatives laterally decorated with polystyrene (PPV-PSt) or poly(ε-caprolactone) (PPP-PCL, PPP-altPCL, PPV-PCL and PPV-PCL-Br). The polymers emit blue and exhibit very high relative and absolute photoluminescence quantum yield, Φ_f, in dilute solution, thin film (spin-coated and inkjet-printed) and bulk state. This is ascribed to the presence of the lateral macromolecules, which suppress the strong π-π interactions and consequently excimers formation. Lower Φ_f value was obtained for the bromine containing polymer and its corresponding model compound dibromodistyrylbenzene Br₂-DSB, which was ascribed to heavy atom effect enabling intersystem crossing from S₁ to T₁. However, studies at 77 K did not reveal phosphorescence, in contrast an enhancement of the fluorescence intensity with respect to room temperature measurement was observed.     

Pyridine-2,5-dicarboxylic acid complexes of nickel(II) with 2,2′-bipyridine and 1,10-phenanthroline coligands; syntheses,crystal structures,spectroscopic and thermal studies

Two pyridine-2,5-dicarboxylic acid (pydcH₂) complexes of nickel(II) with 2,2′-bipyridine and 1,10-phenanthroline were synthesized and characterized by elemental, spectroscopic, thermal analysis, magnetic measurements and single crystal X-ray diffraction techniques. Both [Ni(pydc)(bipy)₂]·7H₂O and [Ni(pydc)(phen)₂]·6.5H₂O crystallize in the monoclinic system and P2₁/c space group. The Ni(II) ions are coordinated by two bidentate bipy or phen ligands and one pydc dianion in a distorted octahedral geometry. The pydc ligand is coordinated through the pyridine nitrogen atom and oxygen atom of carboxyl group as a bidentate ligand. Both carboxylate groups of pydc are deprotonated but only the 2-carboxylate is coordinated to the metal. Thermal decompositions of the complexes have been studied over the range 30–600 °C on heating in a static air atmosphere.     

Rapid and Selective Determination of Vanillin in the Presence of Caffeine,its Electrochemical Behavior on an Au Electrode Electropolymerized with 3‐Amino‐1,2,4‐triazole‐5‐thiol

Electrochemical oxidation of vanillin (VAN) in the presence of caffeine (CAF) was studied on a gold (Au) electrode modified with 3‐amino‐1,2,4‐triazole‐5‐thiol (ATT) film by using differential pulse voltammetry (DPV) and cyclic voltammetry (CV) method. The formation of the ATT film on the Au electrode surface was characterized by the CV, fourier transform infrared spectroscopy (FTIR) and impedance spectroscopy (EIS) methods. A single irreversible oxidation peak of the VAN was obtained by using the CV method. The determination of VAN in the presence of CAF was carried out at pH 4 in Britton Robinson buffer (BR) by the DPV method. Under the optimal conditions, the oxidation peak current was proportional to the concentration of VAN in the range of 1.1 μM to 76.4 μM in the presence of CAF with the correlation coefficient of 0.997 and the detection limit of 0.19 μM (S/N=3). The selective determination of VAN in a commercial coffee sample was carried out with satisfactory results on the ATT‐Au modified electrode.     

Energy absorption buildup factors of some potential bioactive compounds in the energy region 0.015–15 MeV

Kinetic energy released per unit mass relative to air and energy absorption buildup factors has been calculated for some potential bioactive compounds in the energy region of 0.015–15?MeV. The bioactive compounds of 1-aryl-3-dibenzylamino-propane-1-on hydrochloride type Mannich bases were used in this work. Aryl part was changed as C₆H₅ (1), 4-CH₃C₆H₄ (2), C₄H₃S-2-yl (3), 4-FC₆H₄ (4), 4-BrC₆H₄ (5), 4-ClC₆H₄ (6), and 4-NO₂C₆H₄ (7). The energy absorption buildup factors have been calculated for penetration depth of 40 mean free paths. It is observed that kinetic energy released per unit mass relative to air depends on the photon energy and chemical content of compounds. The compounds with least mean atomic number possess the maximum value of energy absorption buildup factors. Also, the energy absorption buildup factors are found the highest in intermediate energy, whereas the lowest in low as well as high energies.     

Preparation of o‐bromobenzophenone derivatives from lithium diarylcuprate(I) reagents

The reaction of lithium diarylcuprate(I) reagents with o‐bromobenzoyl chloride has been investigated. In general, the reaction proceeds well to give synthetically useful o‐bromobenzophenone derivatives as the major product. It is suggested that a minor substituent effect, whereby diarylcuprate reagents containing an ortho or meta substituent react more favourably, may be attributed to small changes in the structure of the organometallic reagent. Copyright © 2000 John Wiley & Sons, Ltd.     

Quantile regression metamodeling: Toward improved responsiveness in the high-tech electronics manufacturing industry

Both technology and market demands within the high-tech electronics manufacturing industry change rapidly. Accurate and efficient estimation of cycle-time (CT) distribution remains a critical driver of on-time delivery and associated customer satisfaction metrics in these complex manufacturing systems. Simulation models are often used to emulate these systems in order to estimate parameters of the CT distribution. However, execution time of such simulation models can be excessively long limiting the number of simulation runs that can be executed for quantifying the impact of potential future operational changes. One solution is the use of simulation metamodeling which is to build a closed-form mathematical expression to approximate the input–output relationship implied by the simulation model based on simulation experiments run at selected design points in advance. Metamodels can be easily evaluated in a spreadsheet environment “on demand” to answer what-if questions without needing to run lengthy simulations. The majority of previous simulation metamodeling approaches have focused on estimating mean CT as a function of a single input variable (i.e., throughput). In this paper, we demonstrate the feasibility of a quantile regression based metamodeling approach. This method allows estimation of CT quantiles as a function of multiple input variables (e.g., throughput, product mix, and various distributional parameters of time-between-failures, repair time, setup time, loading and unloading times). Empirical results are provided to demonstrate the efficacy of the approach in a realistic simulation model representative of a semiconductor manufacturing system.     

THEORY OF POLARIZED FLUORESCENCE FROM MOLECULAR PAIRS: FÖRSTER TRANSFER AT LARGE ELECTRONIC COUPLING

Polarization properties of the fluorescence from a pair of identical molecules coupled electronically are examined on the basis of a stochastic Liouville equation formalism developed in 1979 by Rahman, Knox and Kenkre. The time development of polarization is calculated for random ensembles of rigid molecule pairs under initial conditions that represent either selective excitation or broad-band coherent excitation. We hold that the applicability of the Forster mechanism is not limited to cases of weak coupling, and we indicate the rationale and a method for observing it in cases involving large interaction between transition dipoles.     

Matching Trees for Simplicial Complexes and Homotopy Type of Devoid Complexes of Graphs

We generalize some homotopy calculation techniques such as splittings and matching trees that are introduced for the computations in the case of the independence complexes of graphs to arbitrary simplicial complexes. We then exemplify their efficiency on some simplicial complexes, the devoid complexes of graphs, \(\mathcal {D}(G;\mathcal {F})\) whose faces are vertex subsets of G that induce \(\mathcal {F}\)-free subgraphs, where G is a multigraph and \(\mathcal {F}\) is a family of multigraphs. Additionally, we compute the homotopy type of dominance complexes of chordal graphs.     

LC Assay of Eletriptan in Tablets and In Vitro Dissolution Studies

Eletriptan (ELT) is a new selective serotonin agonist approved for the treatment of acute migraine headaches. A simple and rapid liquid chromatographic method was developed and validated for the assay of ELT in tablets. Chromatography was carried out on a 250 mm × 4.6 mm C₁₈ column at 30 °C. Acetonitrile–15 mM triethylamine solution (adjusted to pH 7.0 using concentrated o-phosphoric acid) (60:40, v/v) mixture was used as mobile phase at 1.0 mL min^?1 flow rate and UV detector was set at 225 nm. A linear response (r ²  = 0.9999) was observed in the range of 0.1–1.6 μg mL^?1. The method showed good recoveries (100.08 %) and the RSD values for intra- and inter-day precision were 0.78–1.93 and 1.10–2.15%, respectively. The method can be used for quality control assays and in vitro dissolution studies of ELT in tablets.