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101.
Melike Büşra Bayramoğlu Karşı Ercan Berberler 《International journal of environmental analytical chemistry》2019,99(5):428-443
The main aim of this study was to present the effects of barbecue smoke on a small-scale environment, a national park under the influence of intense barbecue smoke, and to scientifically support the sustainable usage of the park. Twelve-weekly bulk deposition samples were collected directly at the barbecuing area, and the samples were analysed for 16 US EPA’s priority PAH compounds and major ions. The mean concentrations of the individual PAHs in the bulk deposition samples ranged from 11.8 ng L?1 (Ane) to 1085 ± 581 ng L?1 (IcdP). The most frequently observed PAH compounds in the bulk deposition samples were Np, Anp, Flr, Phe, An, Flu, BkF, BaP and IcdP. The mean total PAH deposition fluxes were determined as 3.6 ± 5.6 µg m?2 day?1. The chloride, potassium and the sulphate fluxes were determined as 145.2 ± 267.8 µg m?2 day?1, 182.9 ± 291.9 µg m?2 day?1, and 111.9 ± 65.9 µg m?2 day?1, respectively. Dominant ions in the bulk deposition samples were potassium ion, chloride and sulphate which addressed as the fingerprint of barbecue grilling. 相似文献
102.
Karásek V Cizmár T Brzobohatý O Zemánek P Garcés-Chávez V Dholakia K 《Physical review letters》2008,101(14):143601
We create extended longitudinally optically bound chains of microparticles with the use of counterpropagating "nondiffracting" light fields, the so-called Bessel beams. The beam homogeneity and extended propagation range allow the creation of 200 microm long chains of organized microparticles. We observe short-range multistability within a single chain and long-range multistability between several distinct chains. Our observations are supported by theoretical results of the coupled dipole method. 相似文献
103.
Kar S Borghesi M Bulanov SV Key MH Liseykina TV Macchi A Mackinnon AJ Patel PK Romagnani L Schiavi A Willi O 《Physical review letters》2008,100(22):225004
Experimental evidence of plasma jets ejected from the rear side of thin solid targets irradiated by ultraintense (>10(19) W cm(-2)) laser pulses is presented. The jets, detected by transverse interferometric measurements with high spatial and temporal resolutions, show collimated expansion lasting for several hundreds of picoseconds and have substantially steep density gradients at their periphery. The role played by radiation pressure of the laser in the jet formation process is highlighted analytically and by extensive two-dimensional particle-in-cell simulations. 相似文献
104.
A. A. Serafetinides M. Makropoulou E. Fabrikesi E. Spyratou C. Bacharis R. R. Thomson A. K. Kar 《Applied Physics A: Materials Science & Processing》2008,93(1):111-116
The use of intraocular lenses (IOLs) is the most promising method to restore vision after cataract surgery. Several new materials,
techniques, and patterns have been studied for forming and etching IOLs to improve their optical properties and reduce diffractive
aberrations. This study is aimed at investigating the use of ultrashort laser pulses to ablate the surface of PMMA and intraocular
lenses, and thus provide an alternative to conventional techniques. Ablation experiments were conducted using various polymer
substrates (PMMA samples, hydrophobic acrylic IOL, yellow azo dye doped IOL, and hydrophilic acrylic IOL consist of 25% H2O). The irradiation was performed using 100 fs pulses of 800 nm radiation from a regeneratively amplified Ti:sapphire laser
system. We investigated the ablation efficiency and the phenomenology of the ablated patterns by probing the ablation depth
using a profilometer. The surface modification was examined using a high resolution optical microscope (IOLs) or atomic force
microscope—AFM (PMMA samples). It was found that different polymers exhibited different ablation characteristics, a result
that we attribute to the differing optical properties of the materials. In particular, it was observed that the topography
of the ablation tracks created on the hydrophilic intraocular lenses was smoother in comparison to those created on the PMMA
and hydrophobic lens. The yellow doped hydrophobic intraocular lenses show higher ablation efficiency than undoped hydrophobic
acrylic lenses. 相似文献
105.
Somnath Roy Tarak Nath Mandal Anil Kumar Barik Samik Gupta Ray J. Butcher Mohamed Salah El Fallah Javier Tercero Susanta Kumar Kar 《Polyhedron》2008
The synthesis and structure of a pyrazole-based orthogonal ferromagnetically coupled tetracopper(II) 2 × 2 homoleptic grid complex [Cu4(PzOAPyz)4(ClO4)2](ClO4)2 · 6H2O (1), formed by the reaction between the ditopic ligand PzOAPyz and Cu(ClO4)2 · 6H2O, are described. The ligand contains terminal pyrazole and pyrazine residues bound to a central flexible diazine subunit (N–N) as well as one potentially bridging alkoxo group. The two adjacent metal centers are linked by an alkoxo oxygen forming essentially a square Cu4(μ-O4) cluster. In the Cu4(μ-O4) core, out of the four copper centers, two copper centers are penta-coordinated and the remaining two are hexa-coordinated. In each case of hexa-coordination, the sixth position is occupied by one of the oxygen atoms of a coordinated perchlorate ion. Complex 1 has been characterized structurally and magnetically. Although the large Cu–O–Cu bridge angles (137–138°) and short Cu–Cu distances (3.964–3.970 Å) are suitable for the transmission of the expected antiferromagnetic coupling, the square-based Cu4(μ-O4) cluster exhibits an intramolecular ferromagnetic exchange (J = 7.47 cm−1) between the metal centers with an S = 2 magnetic ground state associated with the quasi orthogonal arrangement of the magnetic orbitals (dx2-y2). The exchange pathway parameters have been evaluated from density functional calculations. 相似文献
106.
Tan KT Vogt BD White CC Steffens KL Goldman J Satija SK Clerici C Hunston DL 《Langmuir : the ACS journal of surfaces and colloids》2008,24(17):9189-9193
The origins for abrupt adhesion loss at a critical relative humidity (RH) for polymeric adhesives bonded to inorganic surfaces have been explored using a model poly(methyl methacrylate) (PMMA) film on glass. The interfacial and bulk water concentrations within the polymer film as a function of D 2O partial pressure were quantified using neutron reflectivity. Adhesion strength of these PMMA/SiO 2 interfaces under the same conditions was quantified using a shaft loaded blister test. A drop in adhesion strength was observed at a critical RH, and at this same RH, a discontinuity in the bulk moisture concentration occurred. The moisture concentration near the interface was higher than that in the bulk PMMA, and at the critical RH, the breadth of the interfacial water concentration distribution as a function of distance from the SiO 2/PMMA interface increased dramatically. We propose a mechanism for loss of adhesion at a critical RH based upon the interplay between bulk swelling induced stress and weakening of the interfacial bond by moisture accumulation at the PMMA/SiO 2 interface. 相似文献
107.
We implement a well-established concept to consider dispersion effects within a Poisson-Boltzmann approach of continuum solvation of proteins. The theoretical framework is particularly suited for boundary element methods. Free parameters are determined by comparison to experimental data as well as high-level quantum mechanical reference calculations. The method is general and can be easily extended in several directions. The model is tested on various chemical substances and found to yield good-quality estimates of the solvation free energy without obvious indication of any introduced bias. Once optimized, the model is applied to a series of proteins, and factors such as protein size or partial charge assignments are studied. 相似文献
108.
We report the aqueous solubilities of phenanthrene and several solid three-ring aromatic heterocycles (phenanthridine, acridine, phenazine, thianthrene, phenothiazine, phenoxathiin, phenoxazine, carbazole, dibenzofuran, dibenzothiophene, and 4,6-dimethyldibenzothiophene) at temperatures ranging from 313K to the solute melting point and at a pressure of 5MPa. The data were measured by dynamic saturation method using an in-house-assembled apparatus for pressurized hot water extraction (PHWE). The solute from a known mass of the saturated aqueous solution was transferred to an organic solvent (hexane or toluene), and the organic phase was analyzed by GC/MS. In any of the solutes, the GC/MS records did not indicate any noticeable decomposition within the temperature range of the measurements. The resultant solubilities were converted to activity coefficients of the individual solutes in saturated aqueous solutions, and the results are discussed in terms of temperature and type/number of heteroatoms. 相似文献
109.
Vicker's microhardness study of (100), (010) and (001) faces of a non-linear optical crystal, L-arginine hydrobromide monohydrate (LAHBr)have been reported.(100) plane is found to be the weakest plane. It has been observed that the microhardness decreases with increasing load for the three crystal planes. The microhardness behaviour have been explained successfully with the help of the PSR model proposed by Li and Bradt. Work hardening index n for the three planes are found to be greater than 1.6 which indicates that LAHBr is a soft crystal. 相似文献
110.
Vaisakh Mohan A. Nijamudheen Sudhir Kumar Das Prabhat K. Sahu Usha Pallabi Kar Dr. Abdur Rahaman Dr. Moloy Sarkar 《Chemphyschem》2012,13(17):3882-3892
A new multi‐component chemosensor system comprising a naphthalimide moiety as fluorophore is designed and developed to investigate receptor–analyte binding interactions in the presence of metal and non‐metal ions. A dimethylamino moiety is utilized as receptor for metal ions and a thiourea receptor, having acidic protons, for binding anions. The system is characterized by conventional analytical methods. The absorption and fluorescence spectra of the system consist of a broad band typical for an intramolecular charge transfer (ICT). The effects of various metal‐ion additives on the spectral behavior of the present sensor system are examined in acetonitrile. It is found that among the metal ions studied, alkali/alkaline earth‐metal ions and transition‐metal ions modulate the absorption and fluorescence spectra of the system. As an additional feature, the anion signaling behavior of the system in acetonitrile is studied. A decrease in fluorescence efficiency of the system is observed upon addition of fluoride and acetate anions. Fluorescence quenching is most effective in the case of fluoride ions. This is attributed to the enhancement of the photoinduced electron transfer from the anion receptor to the fluorophore moiety. Hydrogen‐bond interactions between the acidic NH protons of the thiourea moiety and the F? anions are primarily attributed to the fluoride‐selective signaling behavior. Interestingly, a negative cooperativity for the binding event is observed when the interactions of the system are studied in the presence of both Zn2+ and F? ions. NMR spectroscopy and theoretical calculations are also carried out to better understand the receptor–analyte binding. 相似文献