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I tested the hypothesis that temperature, salinity, and dissolved oxygen influence the distribution and abundance of elasmobranchs (sharks, skates, and rays) in Tomales Bay, California. I captured elasmobranchs monthly (September 1990-April 1992) on longlines set in the bay. A Poisson regression under generalized least squares was used to determine that temperature and salinity were the most important factors determining the distribution and abundance of the three most commonly captured species; bat ray, Myliobatis californica, leopard shark, Triakis semifasciata, and brown smoothhound shark, Mustelis henlei. Females of all three species were more abundant than males throughout the bay, and were most abundant in the warmer more saline inner bay. All three species left Tomales Bay in late fall as water temperatures in the bay dropped below 10-12°C, and returned in early spring after temperatures rose above 10°C.The oxygen consumption of bat rays, Myliobatis californica, was determined at 8, 14, 20, and 26°C. Mean, standard, mass-independent metabolic rates (MO2 in mg O2 •kg-0.67 •h-1) of unacclimated rays at each temperature were significantly different from one another. MO2 was extremely temperature sensitive from 20-26°C (Q10 = 6.62), and moderately sensitive at the upper (20-26°C: Q10 = 1.85) and lower (8-14°C: Q10 = 2.23) temperature ranges.The effects of four temperatures (8, 14, 20, 26°C) on blood oxygen equilibrium curves of the bat ray, Myliobatis californica, was investigated. Blood oxygen equilibrium curves at all temperatures were hyperbolic (n50 < 2), with high affinity (low P50), large Bohr factors (0 = -0.45 to -0.52), high blood oxygen carrying capacity (CBO2 = 6.8 to 9.06), and very large non­-bicarbonate buffering capacity (β = -14.25 to -16.43). CBO2, 0, and β are among the largest measured in a poikilothermic elasmobranch. Affinity decreased with increasing temperature except at 26°C. The affinity shift at 26°C and a concomitant 25% drop in CBO2 at this temperature suggests a hemoglobin heterogeneity. Blood oxygen equilibrium curves were temperature insensitive betw en 8-14°C and 20-26°C and most sensitive between 14-20°C, the temperature range in which bat rays are most commonly found in Tomales Bay. Bat rays appear capable of tolerating anoxia and hypercapnia (low P50, n50, and high β), and sustaining high activity levels (high CBO2, 0, and β) by virtue of their unique hematological characteristics.

This article describes an approach to general chemistry that involves teaching chemical concepts in the context of two thematic laboratory modules: environmental remediation and the fate of pharmaceuticals in the environment. These modules were designed based on active-learning pedagogies and involve multiple-week projects that dictate what content is taught and in which order the content is presented. Students were expected to design experimental procedures, analyze data, and communicate their results. A description of the two laboratory modules is included along with a week-by-week description of the student experience.

The solvent and temperature dependence of the reversible reactions of the trisdipicolinate coordination complexes of europium(III) were restudied in water and D2O solutions. The absence of strong solvent-dependent effects on the equilibrium structures of the complexes was reflected in the similar spectral dispersion characteristics observed in the various solution samples. The complexes exhibited varying excitation and emission detection at temperatures ranging from 20 to 80 degree centigrade.

The first detailed analysis of 4f8(Tb3+) electronic energy-level structure in Tb(oda)3(super 3-) complexes is examined using data obtained from optical and chiroptical absorption and emission measurements performed on single crystals of Na3(Ln(oda)3)*2NaClO4*6H2O, or TbODA. The relatively strong chiroptical activity exhibited by TbODA and the other LnODA systems reflects the relatively strong admixtures of electric and magnetic dipole strength in the 4f-4f transitions of these systems.

Na3[Yb(dpa)3].NaClO4.10H2O has a hexagonal symmetry that accepts Tb(dpa)sub3sup3- in Yb(dpa)sub3sup3- substitutions in less than 0.1 Tb3+/Yb3+ concentration ratio without changing its crystal structure. The 60 crystal-field energy levels of the compound are located in the 17 lowest-energy 4f8-[SL]j multiplets of Tb3+. The 4f-electron/crystal-field interactions of Eu(dpa)sub3sup3+, Tb(dpa)sub3sup3+ and Dy(dpa)sub3sup3+ complexes have different anisotropies but the overall cystal field strength of the three systems are similar.

The electronic energy-level structure of Eu(dpa)sub3sup3- in Na3[Yb0.95-Eu0.05(dpa)3].NaClO4.10H2O is similar to Eu(dpa)sub3sup3- in aqueous solution. Single crystals of Na3[Yb0.95Eu0.05(dpa)3].NaClO4.10H2O were measured by optical absorption and emission methods to determine the energy-level structure of Eu(dpa)sub3sup3-. The intensity of the j-multiplet-to-J-multiplet transition manifolds was identical for Eu(dpa)sub3sup3- in solution and in the compound.

Analysis of crystal-field energy-level structure of Na3Yb(sub 1 -x)Dy(sub x)(dpa)3NaClO4.10H2O complex show that the structure of 4f(super 9) in Dy(dpa)3(super 3-) and Dy(oda)3(super 3-) are different. The coordination geometry of these complexes are however similar as both form tris-terdenate chelate structures with trigonal dihedral symmetry and both have a coordination core which achieves a distorted tricapped trigonal prism geometry. The parametric fits of calculated-to-experimental energy levels are obtained by using Hamiltonian parameters.

Unpolarized, linearly polarized, and circularly polarized optical absorption and emission measurements are used to characterized the 4f(super 9) electronic structure of Dy+3 in trigonal Na3Dy(oda)(sub 3)*2NaClO4*6H2O crystals. The results demonstrate the locations and symmetry assignments for 152 crystal-field levels split out of the 4f(super 9)(Dy+3) electronic configuration. Quantitatively analyzed line strengths are reported for 39 of the transition observed in the unpolarized axial absorption spectra.

We report an experimental study of adsorbed monolayers of SF6 on graphite using infrared reflection absorption spectroscopy supplemented by ellipsometry. The asymmetric S–F stretch mode ν3 near 948 cm-1 in the gas is strongly blueshifted in the film by dynamic dipole coupling. This blueshift is very sensitive to the intermolecular spacing in the SF6 layer. We convert the measured frequency ν3 to a lattice spacing a, using a self-consistent field calculation, calibrated by the frequency in the commensurate phase. The resolution in lattice spacing is 0.002 Å, although there is a larger systematic uncertainty associated with nondynamic-dipole contributions to the frequency shift. We map the commensurate-incommensurate transition, a transition between two incommensurate phases, and the melting transition. These results are compared to previous x-ray data. We provide a new determination of the layer critical point (156 K), the layer condensation line down to 110 K, and the spreading pressure at saturation in this temperature range. [ABSTRACT FROM AUTHOR]

We report an experimental study of adsorbed films of C2F6 on graphite by using infrared reflection absorption spectroscopy supplemented by ellipsometry. The vibrational C–F stretch modes ν5 (parallel to the molecular axis) and ν7 (perpendicular) in the film are strongly blueshifted by dynamic dipole coupling, and these shifts are sensitive to lattice spacing and molecular tilt. The relative strength of the absorption peaks mainly depends on the tilt angle relative to the surface normal. We use the strength data to estimate the tilt angle across the known monolayer phases, information that is difficult to obtain by other techniques. Although only the surface-normal component of the induced dipole moment appreciably couples to the external infrared field, surface-parallel components contribute to the intralayer coupling and hence to the frequency shifts for tilted molecules. Comparison to model calculations for a range of herringbone tilt configurations allows us to draw conclusions regarding the pattern of tilt azimuths. On this basis, we offer a revised interpretation of the origin of the Ising-type ordering transition found by Arndt et al. [Phys. Rev. Lett. 80, 1686 (1998)] in heat capacity measurements. Our phase boundaries for monolayer phases above 80 K are in good agreement with earlier results of the Saarbrücken group. We identify three distinct bilayer phases near saturation in isothermal pressure scans from ellipsometric steps and spectroscopic signatures. In temperature scans, we find evidence for several monolayer phases more dense than the well-established 2×2 commensurate phase and for a stable trilayer phase below about 60 K. [ABSTRACT FROM AUTHOR]

Luminescent lanthanide (III) ions have been exploited for circularly polarized luminescence (CPL) for decades. However, very few of these studies have involved chiral samarium (III) complexes. Complexes are prepared by mixing axial chiral ligands (R/S))‐2,2'‐bis(diphenylphosphoryl)‐1,1′‐binaphthyl (BINAPO) with europium and samarium Tris (trifluoromethane sulfonate) (Eu (OTf)3 and Sm (OTf)3). Luminescence‐based titration shows that the complex formed is Ln((R/S)‐BINAPO)2(OTf)3, where Ln = Eu or Sm. The CPL spectra are reported for Eu((R/S)‐BINAPO)2(OTf)3 and Sm((R/S)‐BINAPO)2(OTf)3. The sign of the dissymmetry factors, gem, was dependent upon the chirality of the BINAPO ligand, and the magnitudes were relatively large. Of all of the complexes in this study, Sm((S)‐BINAPO)2(OTf)3 has the largest gem = 0.272, which is one of the largest recorded for a chiral Sm3+ complex. A theoretical three‐dimensional structural model of the complex that is consistent with the experimental observations is developed and refined. This report also shows that (R/S)‐BINAPO are the only reported ligands where gem (Sm3+) > gem (Eu3+). [ABSTRACT FROM AUTHOR]

The main focus is made on the characterization of uranyl ion, which undergoes spectroscopy. The spectroscopic techniques are conducted on solution and frozen glass samples and results show that an interaction with the solvent perturbs the center of symmetry of the UO2Cl(super 2-) ion.