Solvation and lon association in the system AgNO3−CH3CN: A Raman and infrared spectral study

Detailed studies of the Raman and infrared line parameters of AgNO₃?CH₃CN systems ranging from dilute solutions to 9M are reported. A concentration quotient of 1.1M ^?1 was obtained for the formation of the Ag⁺NO ₃ ^? ion pair when C<4M. The complex appears to have point group C_s(σ_V) with Ag⁺ in a “roll-on” position. The Ag⁺ ion is solvated by four molecules of CH₃CN; nitrate ion replaces three of these when bound to Ag⁺. When C>4M, multiple ion aggregates form in the solution. A low-frequency 110 cm^?1 line is ascribed to librational motions of NO ₃ ^? , probably bound to Ag⁺.     

Analysis of the composition of immunoconjugates using size-exclusion chromatography coupled to mass spectrometry

Recombinant monoclonal antibody drug products play an increasingly important role in the treatment of various diseases. Antibodies are large, multi-chain proteins and antibody preparations often contain several molecular variants, which renders them heterogeneous. The heterogeneity is further increased in immunoconjugates prepared by covalently linking several drug molecules per antibody molecule. As part of the product characterization, the molecular weights of the antibodies or their drug conjugates need to be measured. Electrospray ionization mass spectrometry (ESI-MS) is well suited for the analysis of recombinant antibodies and immunoconjugates. Sample preparation is an important element of ESI-MS analysis, in particular samples need to be freed of interfering charged species, such as salts and buffer components. In this paper, Amicon centrifugal filters, reversed-phase high-performance liquid chromatography (HPLC), and size-exclusion HPLC were evaluated for sample desalting. Size-exclusion HPLC, using aqueous acetonitrile as the mobile phase, directly coupled to ESI-MS provided the best performance and was optimized for the study of immunoconjugates. The results showed that antibodies carrying covalently linked maytansinoid molecules generated charge envelope profiles that differ from those of the non-conjugated antibody. For the determination of the distribution of the various conjugate species in an immunoconjugate sample prepared by randomly linking in the average 3.6 drug molecules per antibody molecule, the experimental conditions needed to be carefully selected to allow acquisition of the whole spectrum containing the charge envelopes of all species.     

Integral equation theory for hard spheres confined on a cylindrical surface: anisotropic packing entropically driven

The structure of two-dimensional (2D) hard-sphere fluids on a cylindrical surface is investigated by means of the Ornstein-Zernike integral equation with the Percus-Yevick and the hypernetted-chain approximation. The 2D cylindrical coordinate breaks the spherical symmetry. Hence, the pair-correlation function is reformulated as a two-variable function to account for the packing along and around the cylinder. Detailed pair-correlation function calculations based on the two integral equation theories are compared with Monte Carlo simulations. In general, the Percus-Yevick theory is more accurate than the hypernetted-chain theory, but exceptions are observed for smaller cylinders. Moreover, analysis of the angular-dependent contact values shows that particles are preferentially packed anisotropically. The origin of such an anisotropic packing is driven by the entropic effect because the energy of all the possible system configurations of a dense hard-sphere fluid is the same. In addition, the anisotropic packing observed in our model studies serves as a basis for linking the close packing with the morphology of an ordered structure for particles adsorbed onto a cylindrical nanotube.     

Microwave-optical double resonance in molecular ions. Co+

Microwave—optical double resonance signals have been detected in a mass-selected ion-beam spectrometer for ¹²C¹⁶O⁺. With the optical excitation of fluorescence from the R₁ ($\text{1}\text{2}$) line of the (0,0) band of the A²Π_{$\text{3}\text{2}$} ← X²∑ transition of 20350.6 cm^?1, the microwave resonances occurred at 118101.8 ± 0.2 MHz and at 117694 ± 2 MHz corresponding to the N= 1, J = $\text{3}\text{2}$ ← N = 0, J = $\text{1}\text{2}$ and the N = 1, J = $\text{1}\text{2}$ ← N = 0, J = $\text{1}\text{2}$ transitions.     

A comparison of the solid state structures of the selenium(IV) compounds PhSeX3(X=Cl, Br)

The crystal structures of PhSeX3(X=Cl, Br,) and their spectroscopic data are reported, with the structure of PhSeBr3 exhibiting interesting molecular, charge transfer, and ionic bonding aspects.     

Presenting mathematics in a first‐year engineering course at university

The approach used to teach mathematics to first‐year engineering students at the University of Warwick is described. The instruction is programmed, with weekly assignments and tutorials, so that the learning is self‐paced within each week. Our experiences with this method of teaching are discussed.     

Measuring theWW γ vertex in the processep→γϑX

We present a detailed analysis of the processep→γ?X as a means of studying the gauge structure of theWWγ vertex. We find that the differential cross section of highp _T photons offers a sensitive measure of anomalousWWγ couplings. At HERA \((\sqrt s = 314GeV)\) , after several years of running, theWWγ vertex can be measured to δκ_γ ? _?2.0 ^+2.9 and δλ_γ ? _?2.5 ^+3.0 (95% C.L.). Which offers an improvement over existing constraints from direct measurements using associatedWγ production in \(\bar pp\) collisions but is less sensitive than the competing process at HERA,ep→eWX. For a higher energyep collider, LEP-LHC \((\sqrt s = 1.3TeV)\) , theWWγ vertex can be measured to δδκ_γ ? ± 0.4 and δλκ_γ ? ± 0.1 at 95%C.L. which is more sensitive to λ_γ than the processe ⁺ e ^?→W ⁺ W ^? at the LEP200e ⁺ e ^? collider and is comparable to the LEP200 sensitivity to κ_γ. These values are also roughly comparable to the competing processep→eWX at LEP-LHC and to what is expected from associated γW production at the LHC and SSC for κ_γ but they are about half as sensitive to λ_γ as the LHC and SSC.