Sjögren's Syndrome (SS) is an autoimmune disease that causes extreme dryness, or sicca,of the eyes and mouth, as well as other potential drying of the throat and intestines. Speech, voice, and swallowing problems are common in individuals with SS. Therefore, this study examined the possible changes in acoustic characteristics of monophthongs (/i, æ, α, u, ʌ/) in eight females with SS following laryngeal hydration treatments. An ABAB experimental design was implemented. Treatment consisted of nebulized isotonic saline immediately following completion of audio-recordings. Using acoustic analysis software the duration, formant frequencies, and vowel space area (VSA) was calculated for the participant's vowel productions. Overall the mean duration of the participant's vowel productions increased slightly from baseline measurements through the last treatment phase. Minimal deviations were observed in first and second formant frequency values throughout the study. Only minor differences were found in the participant's VSA from baseline phase of data collection through the final treatment phase, with most of these differences due to a change in the first formant of the /æ/ vowel. Despite the need for future research, the findings of this study increase understanding into how SS impacts speech production.

Photolysis of nitrate ion in the natural environment produces NO, NO2, and O3, releasing these toxic gases into the atmosphere. Work done by other groups has shown ionic strength dependence of the ratio of products from photolysis of aqueous nitrate ion. To better understand the kinetic mechanisms of nitrate photolysis, the effects that ionic strength in solution have on nitrate ion symmetry breaking are needed. Different solvation environments induce nitrate bonding motifs that may be correlated to the product ratio. Fourier-transform infrared spectra of aqueous nitrate–ion solutions were obtained over a range of temperatures for several total electrolyte concentrations. The electric fields (arising from water molecules and ions in solution) in aqueous potassium nitrate solution distort the trigonal planar shape of the nitrate ion, which may favor a specific initial path of the decomposition of nitrate during photolysis. Van’t Hoff plots of the relative peak areas corresponding to the formally-degenerate asymmetric stretching mode reveal the relative energies of the two solvation geometries. The difference in energy between the two geometries is linearly proportional to the ionic strength of the solution. Electronic structure calculations suggest that the more symmetric geometry has an increased stability relative to the less-symmetric geometry in high ionic strength solutions. Thus, the relative amounts of the nitrate ion solvation geometries can be correlated to the amount of products produced during photolysis to help explain the ionic-strength dependence of the product yields. Nitrate geometries at the water—CCl4 interface and aqueous carbonate ion bonding motifs are being investigated to identify pure-water effects. Preliminary results suggest that the more symmetric geometry nitrate is stabilized at the water—CCl4 interface and the lesssymmetric carbonate solvation geometry has an increased stability relative to the more symmetric geometry in high ionic strength solutions.

Deuterium ratios (δD) of hydrated volcanic glass have been used to reconstruct paleoenvironments, although the reliability and proper sample preparation protocol have been debated. In this study, hydrated volcanic ash samples from the lee of the Cascades were prepared using two separate methods. Method 1 involves sonicating and rinsing samples with hydrochloric acid (HCl) followed by hand-selection of glass shards (125-212µm). Method 2 requires hydrochloric acid (HCl) and hydrofluoric acid (HF) abrasion as well as heavy liquid separation of shards (70-150µm). Method 2 produced more consistent results with decreased intra-replicate variability in both water content (-0.92 wt. %) and deuterium values (-2.5‰ δD). Method 2 δD values of ≥99% isotropic glass were also 2.5-10 % more negative relative to Method 1 values, with an increasing discrepancy with age (3.68-32.66 Ma). Method 2 results suggest volcanic glass did not re-equilibrate with modern water, based on 1) < 2‰ discrepancies between samples of the same ash flow taken from unique sample localities and 2) a ~20‰ difference between samples of different ages (~8 Ma apart) from the same locality. These results support the specified use of HF abrasion and heavy liquid separation on 70-150 µm glass shards to minimize the impact of contaminants on reconstructed paleowater δD values.

Water has long been assumed to be essential for biological function. To understand the molecular basis of the role of water in protein function, several studies have established a correlation between enzyme activity and hydration level. While a threshold of hydration of 0.2 h (grams of water per gram of dried protein) is usually accepted for the onset of enzyme activity, recent works show that enzyme activity is possible at water contents as low as 0.03 h (Lind et al., 2004). Diffusion limitation in these experiments was avoided by monitoring enzyme-catalyzed hydrolysis of gas-phase esters. However, since water is also a substrate for the enzyme used in these experiments, they cannot be used to probe the possibility of activity at zero hydration. However, the pig liver esterase and C. rugosa lipase B are able to catalyse alcoholysis reactions in which an acyl group is transferred between an ester and an alcohol. Therefore, by following this reaction and using a gas phase catalytic system, we have been able to show that activity can occur at 0 g/g. These results led to the question of the accuracy of determinations of very low water concentrations; i.e., how dry is 0 g/g? Although gravimetric measurements of the hydration level do not allow us to define the anhydrous state of the protein with sufficient sensitivity, using 18O-labeled water, we have been able to quantify the small number of water molecules bound to the protein after drying, using a modification of the method of Dolman et al. (1997). Testing different drying methods, we have been able to determine a level of hydration as low as 2 moles of water per mole of protein (equivalent to 0.0006 h in the case of pig liver esterase) and have shown that in the case of the pig liver esterase, activity can occur at this hydration level. At the molecular level, if the hydration level affects activity, we can expect an effect on the protein dynamics. Neutron scattering spectra of hydrated powders, for instance, show that diffusive motions of the protein increase with the hydration (Kurkal et al., 2005) To address the question of the protein motions involved in the onset of enzyme activity at low hydration, we performed neutron scattering experiments on a pico-second time scale on dried powders. Preliminary results show a dynamical transition at hydration levels as low as 3 h. Molecular dynamic simulations have also been used in this study to access the dynamics of the active site. Overall, the results here show that pig liver esterase can function at zero hydration, or as close to zero hydration as current methods allow us to determine. Since the experimental methodology restricts this work to a small number of enzymes, it is unlikely that it will ever be possible to determine if all enzymes can function in the anhydrous state: however, the results here indicate that water is not an obligatory requirement for enzyme function.

Herman J.C. Berendsen. / "July 2, 1962"--Cover. "Reprinted from the Journal of chemical physics, vol. 36, no. 12, 3297-3305, June 15, 1962." / Bibliography: p. 48. / Army Signal Corps Contract DA36-039 sc-78108. Dept. of the Army Task 3-99-20-001 and Project 3-99-00-000.

Cytochrome c oxidase couples the reduction of dioxygen to proton pumping against an electrochemical gradient. The D-channel provides the principal uptake pathway for protons. A water chain is thought to mediate the relay of protons through the D-channel, but it is interrupted at N139 in all crystallographic structures. Here, free energy simulations are used to examine the proton uptake pathway in the wild type and in single-point mutants N139V and N139A, where reduction and pumping is compromised. A general approach for the calculation of water occupancy in protein cavities is presented and demonstrates that combining efficient sampling algorithms with long simulation times is required to achieve statistical convergence of equilibrium properties in the protein interior. The relative population of conformational and hydration states of the D-channel is characterized. Results shed light onto the role of N139 in the mechanism of proton uptake and clarify the physical basis for inactive phenotypes.

Portland-limestone cements (PLC) have been used in practice for a considerable period of time in several countries. In 2008, the CSA A3000 cements committee approved the addition of a new class of cement with up to 15% interground limestone. The CSA A23.1 concrete committee also approved the use of PLC in concrete in 2009. However, to date, due to uncertainty about the performance of Portland-limestone cements in sulfate environments, their use has not been allowed in sulfate exposures. In this study, the sulfate resistance of five different Portland-limestone cements and their combinations with various amounts of supplementary cementitious materials (SCMs) were examined. Besides the standard tests performed at 23 °C, a modified version of the ASTM C1012 test was developed in this study (adopted in 2010 as CSA A3004-B) and used to investigate the possibility of thaumasite form of sulfate attack at 5 °C. It was found for tests conducted at 23 °C that while 100% cement mixes deteriorated in sulfate exposure due to conventional sulfate attack, partially replacing the Portland cements and Portland-limestone cements with 30% or 50% slag was effective in making the mixes highly sulfate-resistant. In sulfate exposure at 5 °C, all of the 100% cement mortar bars failed the test and had completely disintegrated due to the formation of thaumasite. Partially replacing cement with 30% slag was effective in controlling the deterioration at 5 °C only for Portland cements and not Portland-limestone cements. However, all the combinations of the cements with 50% slag were resistant to the thaumasite form of sulfate attack. In a parallel study, the hydration of Portland-limestone cements and the relationship between strength and porosity of mortar samples were examined. The results of hydration studies revealed that the limestone portion of Portland-limestone cements reacts with the alumina phases and produces carboaluminates, which contributes to the strength. As the limestone content of the cement increased, the shift in the optimum level of SCM providing maximum strength and minimum porosity was attributed to the availability of more alumina, which allowed more limestone to participate in the hydration reactions, forming additional carboaluminate hydrates.

Cytochrome c oxidase couples the reduction of dioxygen to proton pumping against an electrochemical gradient. The D-channel provides the principal uptake pathway for protons. A water chain is thought to mediate the relay of protons through the D-channel, but it is interrupted at N139 in all crystallographic structures. Here, free energy simulations are used to examine the proton uptake pathway in the wild type and in single-point mutants N139V and N139A, where reduction and pumping is compromised. A general approach for the calculation of water occupancy in protein cavities is presented and demonstrates that combining efficient sampling algorithms with long simulation times is required to achieve statistical convergence of equilibrium properties in the protein interior. The relative population of conformational and hydration states of the D-channel is characterized. Results shed light onto the role of N139 in the mechanism of proton uptake and clarify the physical basis for inactive phenotypes.

Deuteron 1D and 2D NMR spectroscopy was used to study the dynamics of water molecules within the mesoporous material MCM-41. The deuteron spectra show three magnetization components for a sample hydrated to a 0.2 monolayer level. One component was assigned to the pore surface silanol group deuterons that exhibit a broad Gaussian line of 32.6 kHz FWHM and the other components were assigned to the water deuterons. At room temperature one water deuteron component has a powder pattern line shape (splitting of about 4.2 kHz and population of about 61%) and the other has a Lorentzian line shape (about 388 Hz FWHM and population of 39%). Magnetization exchange occurs between these components. An exchange model, based on multi-site exchange, was constructed and used to analyse the results for exchange. For the 0.2 monolayer sample the rate of magnetization exchange out of the hydration site where the water deuterons exhibit a Lorentzian line in the deuteron spectra is 1.3 ms. 2D measurements at 233 K and room temperature confirmed the magnetization exchange scenario for the two water deuteron sites. Combining the deuteron results with proton-silicon cross polarization magic angle spinning experiments together with heat treatment of the sample, definitive hydration site identification for MCM-41 was achieved. This study has shown that the water molecules bound to the hydrogen-bonded silanol groups produce the powder pattern while water molecules bound to the single silanol groups produce the Lorentzian line. This represents a necessary first step toward a meaningful modeling of NMR observables in terms of site-specific water molecule coordination and dynamics in MCM-41.

Deuteron 1D and 2D NMR spectroscopy was used to study the dynamics of water molecules within the mesoporous material MCM-41. The deuteron spectra show three magnetization components for a sample hydrated to a 0.2 monolayer level. One component was assigned to the pore surface silanol group deuterons that exhibit a broad Gaussian line of 32.6 kHz FWHM and the other components were assigned to the water deuterons. At room temperature one water deuteron component has a powder pattern line shape (splitting of about 4.2 kHz and population of about 61%) and the other has a Lorentzian line shape (about 388 Hz FWHM and population of 39%). Magnetization exchange occurs between these components. An exchange model, based on multi-site exchange, was constructed and used to analyse the results for exchange. For the 0.2 monolayer sample the rate of magnetization exchange out of the hydration site where the water deuterons exhibit a Lorentzian line in the deuteron spectra is 1.3 ms. 2D measurements at 233 K and room temperature confirmed the magnetization exchange scenario for the two water deuteron sites. Combining the deuteron results with proton-silicon cross polarization magic angle spinning experiments together with heat treatment of the sample, definitive hydration site identification for MCM-41 was achieved. This study has shown that the water molecules bound to the hydrogen-bonded silanol groups produce the powder pattern while water molecules bound to the single silanol groups produce the Lorentzian line. This represents a necessary first step toward a meaningful modeling of NMR observables in terms of site-specific water molecule coordination and dynamics in MCM-41.