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Abstract:An aluminum fluoride, A1F;3, forms during HF digestion of felsic rock samples, for trace element and isotope geochemistry, which use a Teflon bomb at high temperature and pressure. The AIF;3 incorporates trace elements (Rb, Sr, Y, Cs, Ba, REE, Pb, Th, and U), and can not be decomposed by conventional methods such as evaporation with HC104. The production of this A1F;3 results in lower yields and poor accuracy in analyses of these trace elements by ICP-MS. The formation of AlF;3 is controlled by the chemical composition of the rock samples, in particular, A1F,3 does not form during decomposition of mafic samples with relatively high (Mg+Ca)/Al ratios. We have developed a new method to suppress the AlF;3 formation, in which excess Mg is added to the sample prior to acid digestion in the bomb. This new method makes it possible to accurately determine the trace element compositions of higher-Al rock samples with lower concentrations of Mg and Ca (e.g. rhyolite and granite). In the trace element analyses by TIMS with isotope dilution techniques (ID-TIMS), AlF.3 formation hinders the achievement of isotope equilibrium, resulting in erroneous results. However, the Mg-addition method removed this problem by suppression of AlF;~ formation.

A 51-year-old woman with known dextrocardia presented with left-sided abdominal pain and symptoms consistent with biliary colic and cholelithiasis. Abdominal ultrasound confirmed the diagnosis of gallstones, as well as situs inversus with the liver and gallbladder on the left side and the spleen on the right. Laparoscopic cholecystectomy was performed without incident. The procedure was uncomplicated except for being the mirror image of that done with the gallbladder in the normal location. Cholelithiasis occurring with situs inversus is rare and may present a diagnostic problem. The extrahepatic anatomy of the biliary and venous system is the mirror image of the right sided liver. Historic and genetic aspects of situs inversus, as well as current theories regarding its etiology are presented. Situs inversus totalis does not appear to be a contraindication to laparoscopic treatment of cholelithiasis.

Fabrication of cone-shaped subwavelength structures by utilizing a confined convective self-assembly technique and inductively coupled-plasma reactive-ion etchingThe use of surface-adsorbed monodisperse polystyrene spheres as a template for forming nanosized particles is described. This simple, yet general method is applicable to virtually any material that can be evaporated or sputtered, and monodisperse particles in the size range from tens of nanometers up to tens of micrometers are readily formed. We will demonstrate its versatility principally through the formation of Au particles having various optical properties produced by modifying their size and shape. We will further show that by changing the density of adsorbed polystyrene spheres as well as adsorbing spheres of two different sizes onto the same substrate allows further modifications of optical properties. Particles formed by this method promise to find a wide range of applications to products such as optical filters, substrates for spectroscopy, sensors, etc.

A surface-adsorbed monolayer of cap-shaped gold particles upon submicrometer-sized polystyrene spheres exhibits pronounced absorption in the visible region. When the surrounding refractive index was altered by immersion in a fluid, the direction of the shift in the absorption spectrum was dependent on the incidence angle of the irradiation. When a thiol molecule, known to adsorb selectively on gold upon polystyrene, was added, the resultant shift in the absorption spectrum's peak was consistently toward longer wavelengths. Consequently, at certain incidence angles, a change in the refractive index of the surrounding fluid produces no shift, whereas thiol adsorption results in a clear shift, apparently reflecting the different spatial regions in which the refractive index is altered by these two procedures.

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Bacteriorhodopsin (bR) has been biosynthetically prepared with lysine deuterated at its a carbon (Ca-H). The labeled membranes containing bR were investigated by difference Fourier transform infrared (FTIR) spectroscopy. It has been derived from K/bR and M/bR difference spectra (K and M are photocycle intermediates) that several bands previously assigned to the retinal chromophore are coupled to the Ca-H. The vibrational modes that exhibit this coupling are principally associated with C15-H and N-H vibrations. [Ca-2H]Lysine-labeled bR was fragmented enzymatically, and bR structures were regenerated with the Ca-2H label either on lysine-216 and -172 or on the remaining five lysine residues of the protein. FTIR studies of the regenerated bR system, together with methylation of all lysines except the active-site lysine, reveal that the changes observed due to backbone labeling arise from the active-site lysine. The intensity of the C15-H out-of-plane wag is interpreted as a possible indication of a twist around the C15=N bond.Bacteriorhodopsin (bR), a 26-kDa pigment, acts as a lightdriven proton pump in the cell membrane of Halobacterium halobium (1). bR is composed of a chromophore (retinal) covalently linked to an amino acid polypeptide chain through the e-amino group of a lysine residue. The configuration of the chromophore of bR5a (light-adapted, proton-pumping active form) is an all-trans-retinal, and the linkage is through a protonated Schiff base (RSBH+) (2) (Fig. 1). Time-resolved absorption spectra on the light-adapted form reveals a photocycle that is kinetically coupled to proton transport (3,4). In this photocycle, spectroscopically distinct intermediates appear, which are designated J625, K630, L550, M412, N520, and Ow. Resonance Raman (RR) and Fourier transform infrared (FTIR) spectroscopy have been shown to be powerful tools for obtaining structural information on the light-induced structural alterations of the active-site retinal and various amino acids (5, 6). In all of these investigations, the possibility of structural alterations in the active-site lysine has not been addressed. McMaster and Lewis (7) have focused on the problem of lysine, and they showed that numerous bands in the previously investigated FTIR difference spectra associated with light absorption by the chromophore involved lysine. In this paper, we extend these measurements to include contributions to the FTIR spectra of the backbone of lysine. We prove that these contributions arise from the lysine that is complexed to the retinal chromophore, and we show that active-site lysine backbone vibrations are strongly coupled to modes that have been assigned previously to retinal. Furthermore, we observe that the nature of the coupling to the backbone is altered in going from bR to K.MATERIALS AND METHODS Lysine deuterated at the a carbon (Ca-H) was synthesized in a similar fashion to the method of Johns and Whelan (8). Incorporation into bR was carried out by growing halobacteria on a defined medium in which lysine was repl...