New interface plate for microspray ionization mass spectrometry

A new interface plate was employed in microspray ionization mass spectrometry (μESI-MS) to improve ion transmission from the sprayer into the sampling nozzle of the mass spectrometer at atmospheric pressure. Using a time-of-flight mass spectrometer (TOFMS), a fivefold increase in ion intensity and a sevenfold reduction in method detection limit were observed. The interface plate attenuated the dependence of the ion intensity on the sprayer position. Even when the distance between the sprayer tip and sampling nozzle was 15.0 mm, ion signals were still stronger than when the sprayer tip was positioned 3.0 mm in front of the sampling nozzle with the original interface plate. This enhancement in the performance of μESI-MS was due to the improved shapes of the equipotential lines near the sprayer tip and the long desolvation distance between the sprayer and the sampling nozzle of the MS.     

Modeling the synergy level in a vertical collaborative supply chain through the IMP interaction model and DEA framework

This work develops a mathematical programming model that characterizes the main variables present in the interaction dynamics of each agent in a collaborative vertical logistical system, such as a supply chain, and measures the synergy level of such system. The model is based on the interaction model developed by the IMP (Industrial Marketing and Purchasing) group and also on the DEA (Data Envelopment Analysis) framework. The basics of these two approaches allow modeling of the characteristics of an agent as well as the collaborative relationships with other agents within the chain. The model was validated using information of supply chain of leather and its products, classified by DANE (Departamento Nacional de Estadistica—Colombia) as the sector CIIU323.     

Formation and Stability of Gaseous WS2Cl2, WS2Br2 and WS2I2 – A Combined Experimental and Theoretical Study

Gaseous WS₂Cl₂ and WS₂Br₂ are formed by the reaction of solid WS₂ with chlorine resp. bromine at temperatures of about 1000 K. This could be shown by mass spectrometric measurements. The heats of formation and entropies of WS₂Cl₂ and WS₂Br₂ have been determined by means of mass spectrometry (MS) and quantum chemical calculations (QC). WS₂I₂ could not be detected by experimental methods. This is in line with the quantum chemically determined equilibrium constant of the formation reaction. The following values are given:, Δ_fH⁰₂₉₈(WS₂Cl₂) = –230.8 kJ · mol^–1 (MS), Δ_fH⁰₂₉₈(WS₂Cl₂) = –235.0 kJ · mol^–1 (QC),, S⁰₂₉₈(WS₂Cl₂) = 370.7 J · K^–1 · mol^–1 (QC) and, c_p⁰_T(WS₂Cl₂) = 103.78 + 7.07 × 10^–3 T – 0.93 × 10⁵ T^–2 – 3.25 × 10^–6 T² (298.15 K < T < 1000 K) (QC). Δ_fH⁰₂₉₈(WS₂Br₂) = –141.9 kJ · mol^–1 (MS), Δ_fH⁰₂₉₈(WS₂Br₂) = –131.5 kJ · mol^–1 (QC),, S⁰₂₉₈(WS₂Br₂) = 393.9 J · K^–1 · mol^–1 (QC) and, c_p⁰_T(WS₂Br₂) = 104.84 + 5.32 × 10^–3 T – 0.75 × 10⁵ T^–2 – 2.45 × 10^–6 T² (298.15 K < T < 1000 K) (QC). Δ_fH⁰₂₉₈(WS₂I₂) = –18.0 kJ · mol^–1 (QC), S⁰₂₉₈(WS₂I₂) = 409.9 J · K^–1 · mol^–1 (QC) and, c_p⁰_T(WS₂I₂) = 105.17 + 4.77 × 10^–3 T – 0.67 × 10⁵ T^–2 – 2.19 × 10^–6 T² (298.15 K < T < 1000 K) (QC). These molecules have the expected C_2v‐symmetry.     

A Hardy Inequality for Ultraspherical Expansions with an Application to the Sphere

We prove a Hardy inequality for ultraspherical expansions by using a proper ground state representation. From this result we deduce some uncertainty principles for this kind of expansions. Our result also implies a Hardy inequality on spheres with a potential having a double singularity.     

Verifying the presence of low levels of neptunium in a uranium matrix with electron energy-loss spectroscopy

This paper examines the problems associated with analysis of low levels of neptunium in a uranium matrix with electron energy-loss spectroscopy (EELS) on the transmission electron microscope (TEM). The detection of neptunium in a matrix of uranium can be impeded by the occurrence of a plural scattering event from uranium (U-M₅ + U-O_4,5) that results in severe overlap on the Np-M₅ edge at 3665 eV. Low levels of Np (1600–6300 ppm) can be detected in a uranium solid, uranophane [Ca(UO₂)₂(SiO₃OH)₂(H₂O)₅], by confirming that the energy gap between the Np-M₅ and Np-M₄ edges is at 184 eV and showing that the M₄/M₅ ratio for the neptunium is smaller than that for uranium. The Richardson–Lucy deconvolution method was applied to energy-loss spectral images and was shown to increase the signal to noise ratio.     

Nonexistence of the Lanczos potential for the Riemann tensor in higher dimensions

The existing refutal, in four-dimensional spacetimes, of the conjecture that the Lanczos tensor can be used as a potential for the Riemann tensor, is derived in a much simpler manner which is valid for dimension n 4 and any signature.     

The photoelectron spectra of D2d and C2ν hydrocarbons containing two norbornadiene or quadricylane groups

The photoelectron spectra of the hydrocarbons 1 to 4 have been recorded and interpreted by qualitative correlation with the spectra of their subsystems norbornadiene, quadricyclane, allene and cyclopropane. It has been shown that the interactions of the symmetry adapted orbitals of the subsystems are governed not only by their symmetry behaviour with respect to D_2d in 1 and 2 , or C_2ν in 3 and 4 , but also by the local symmetry at the points of attachment of the subsystems.