The porosities of three mesoporous silica materials were characterized with {sup 129}Xe NMR spectroscopy. The materials were synthesized by a sol-gel process with r = 0, 25, and 70% methanol by weight in an aqueous cetyltrimethylammonium bromide solution. Temperature dependent chemical shifts and spin lattice relaxation times reveal that xenon does not penetrate the pores of the largely disordered (r= 70%) silica. For both r = 0 and 25%, temperature dependent resonances corresponding to physisorbed xenon were observed. An additional resonance for the r = 25% sample was attributed to xenon between the disordered cylindrical pores. 2D NMR exchange experiments corroborate the spin lattice relaxation data which show that xenon is in rapid exchange between the adsorbed and the gas phase.

Newspaper from Rose State College in Midwest City, Oklahoma that includes national, local, and campus news along with advertising.

Previous work focused on the production of carbon fiber composites and subsequently activating them to induce adsorbent properties. One problem related to this approach is the difficulty of uniformly activating large composites. In order to overcome this problem, composites have been made from pre-activated fibers. The loss of surface area upon forming the composites after activation of the fibers was investigated. The electrical resistivity and strength of these composites were compared to those made by activation after forming. It was found that the surface area is reduced by about 35% by forming the composite from pre-activated fibers. However, the properties of the activated sample are very uniform: the variation in surface area is less than {+-}0.5%. So, although the surface area is somewhat reduced, it is believed that making composites from pre-activated fibers could be useful in applications where the BET surface area is not required to be very high. The strength of the composites produced from pre-activated fibers is lower than for composites activated after forming when the carbon burnoff is below 45%. For higher burnoffs, the strength of composites made with pre-activated fibers is as good or better. In both cases, there is a dramatic decrease in strength …

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Examination of corrosion coupons by transmission electron microscopy after their exposure in the Idaho Advanced Test Reactor (ATR) has broadened the Zircaloy-4 precipitate-amorphization database and validated a new kinetic model for previously unavailable values of temperature and fast-neutron flux. The model describes the amorphization of Zr(Fe,Cr){sub 2} intermetallic precipitates in zirconium alloys as a dynamic competition between radiation damage and thermal annealing that leaves some iron atoms available for flux-assisted diffusion to the zirconium matrix. It predicts the width of the amorphous zone as a function of neutron flux (E>1 MeV), temperature, and time. In its simplest form, the model treats the crystalline/amorphous and precipitate/matrix interfaces as parallel planes, and its accuracy decreases for small precipitates and high fluence as the amorphous-zone width approaches precipitate dimensions. The simplest form of the model also considers diffusion to be rate-determining. This is an accurate approximation for steady-state conditions or slow changes in flux and temperature, but inappropriate for the analysis of faster transients. The paper addresses several difficulties inherent in measuring amorphous-zone width, and utilizes the expanded database to evaluate the improvements in predictive accuracy available through both conversion of the model to spherical coordinates and extension of its time dependency.

The design of the NLC Beam Delivery System requires a firmer understanding of the effects of collimators on short, intense bunches than is presently available. We describe an experiment to directly measure these effects through use of a dedicated apparatus located at the 1.19 GeV point in the SLAC Linac. The apparatus consists of an outer vacuum vessel and an interchangeable insertion containing up to 5 distinct collimator apertures. The insertion is capable of remote-controlled translation, allowing the collimator apertures to be misaligned relative to the electron beam without changing the incoming beam orbit; the wakefield deflection is then measured by observing the change in the outgoing orbit on 32 beam position monitors. The parameters of the apertures have been selected to allow confirmation of the scaling laws for collimator wakefields, and to strongly enhance either the geometric or resistive wall contribution of each aperture. Details of the apparatus design, the aperture parameters, and the experimental program are discussed.

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The dynamic aperture for version 5.1, with a 300{mu}r crossing angle at IP1 and IP5, of the Large Hadron Collider (LHC) lattice has been estimated using the tracking code TEVLAT. The dynamic aperture calculated here is due to the magnetic field errors in the high gradient quadrupoles (MQX) in the two low-{beta} interaction regions at IR1 and IR5. No errors were assigned to the magnets in the arc regions of the lattice, nor were beam-beam effects incorporated. The dynamic aperture is expressed in terms of the {sigma} of the beam corresponding to the beam emittance of 3.75mm mr. With only short term tracking, the combined effect of the multipoles and the crossing angle is to yield an average (over multipole coefficients generated with 100 different seeds) dynamic aperture of {approx} 11.7 {plus_minus} 1.2{sigma}.

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NIST-built 10 T{Omega} and commercial 1 T{Omega} standard resistors were hand carried between NIST and Sandia for a high resistance comparison. The comparison tested the ruggedness of the new NIST-built standard resistors, provided a check of the scaling between the two laboratories, supported measurements to reestablish NIST calibration services at 10 T{Omega} and 100 T{Omega}, and demonstrated the possibility of establishing a NIST high resistance measurement assurance program (MAP). The comparison has demonstrated agreement on the order of 0.07% which is within the expanded uncertainties (coverage factor = 2) of NIST and Sandia at 1 T{Omega} and 10 T{Omega}.

In theories with large extra dimensions, constraints from cosmology lead to non-trivial lower bounds on the gravitational scale M, corresponding to upper bounds on the radii of the compact extra dimensions. These constraints are especially relevant to the case of two extra dimensions, since only if M is 10 TeV or less do deviations from the standard gravitational force law become evident at distances accessible to planned sub-mm gravity experiments. By examining the graviton decay contribution to the cosmic diffuse gamma radiation, we derive, for the case of two extra dimensions, a conservative bound M > 110TeV, corresponding to r{sub 2} < 5.1 x 10{sup -5} mm, well beyond the reach of these experiments. We also consider the constraint coming from graviton overclosure of the universe and derive an independent bound M > 6.5/{radical}h TeV, or r{sub 2} < .015hmm.

Weekly newspaper from Dallas, Texas that includes local, state, and national news and advertising of interest to the Lesbian, Gay, Bisexual, and Transgender (LGBT) community.

Density-functional electronic structure calculations have been used to investigate the high pressure behavior of Am. At about 80 kbar (8 GPa) calculations reveal a monoclinic phase similar to the ground state structure of plutonium ({alpha}-Pu). The experimentally suggested {alpha}-U structure is found to be substantially higher in energy. The phase transition from fcc to the low symmetry structure is shown to originate from a drastic change in the nature of the electronic structure induced by the elevated pressure. A calculated volume collapse of about 25% is associated with the transition. For the low density phase, an orbital polarization correction to the local spin density (LSD) theory was applied. Gradient terms of the electron density were included in the calculation of the exchange/correlation energy and potential, according to the generalized gradient approximation (GGA). The results are consistent with a Mott transition; the 5f electrons are delocalized and bonding on the high density side of the transition and chemically inert and non-bonding (localized) on the other. Theory compares rather well with recent experimental data which implies that electron correlation effects are reasonably modeled in our orbital polarization scheme.

The Biotechnology Center for Fuels and Chemicals (BCFC) leads a national effort, in cooperation with industry, to develop innovative, market-driven biotechnologies for producing fuels and chemicals from renewable resources. The BCFC researchers focus on using bioprocesses to convert renewable biomass feedstocks into valuable products.

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The groundwater in the uppermost aquifer beneath the F-Area Hazardous Waste Management Facility (HWMF), also known as the F-Area Seepage Basins, at the Savannah Site (SRS) is monitored periodically for selected hazardous and radioactive constituents. This report presents the results of the required groundwater monitoring program.

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Infrared thermal imaging has become increasingly popular as a nondestructive evaluation method for characterizing materials and detecting defects. One technique, which was utilized in this study, is front-flash thermal imaging. We have developed a thermal imaging system that uses this technique to characterize advanced material systems, including continuous fiber ceramic composite (CFCC) components. In a front-flash test, pulsed heat energy is applied to the surface of a sample, and decay of the surface temperature is then measured by the thermal imaging system. CFCC samples with drilled flat-bottom holes at the back surface (to serve as ''flaws'') were examined. The surface-temperature/time relationship was analyzed to determine the depths of the flaws from the front surface of the CFCC material. Experimental results on carbon/carbon and CFCC samples are presented and discussed.

Recently, it has been proposed that the fundamental scale of quantum gravity can be close to the weak scale if there are large extra dimensions . This proposal has important phenomenological implications for processes at the TeV scale. We study the process {gamma}{gamma} {r_arrow} {gamma}{gamma}, assuming an ultraviolet cutoff M{sub S} {approximately} 1 TeV for the effective gravity theory. We find that, at center of mass energies {radical}s {approximately} 1 TeV, the contribution of gravitationally mediated scattering to the cross section is comparable to that coming from the one-loop Feynman diagrams of the Standard Model. We thus conclude that the effects of weak scale quantum gravity can be studied at the Next Linear Collider (NLC), in the photon collider mode. Our results suggest that, for typical proposed NLC energies and luminosities, the range 1 TeV {le} M{sub S} {le} 10 TeV can be probed.

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The groundwater in the uppermost aquifer beneath the H-Area Hazardous Waste Management Facility (HWMF), also known as the H-Area Seepage Basins, at the Savannah Site (SRS) is monitored periodically for selected hazardous and radioactive constituents. This report presents the results of the required groundwater monitoring program.

Progress towards the development of such algorithms as been reported for waveguide analysis'-3and vertical-cavity laser simulation. In all these cases, the higher accuracy order was obtained for a single spatial dimension. More recently, this concept was extended to differencing of the Helmholtz Equation on a 2-D grid, with uniform regions treated to 4th order and dielectric interfaces to 3'd order5. No attempt was made to treat corners properly. In this talk I will describe the extension of this concept to allow differencing of the Helmholtz Equation on a 2-D grid to 6* order in uniform regions and 5* order at dielectric interfaces. In addition, the first known derivation of a finite difference equation for a dielectric comer that allows correct satisfaction of all boundary conditions will be presented. This equation is only accurate to first order, but as will be shown, results in simulations that are third-order-accurate. In contrast to a previous approach3 that utilized a generalized Douglas scheme to increase the accuracy order of the difference second derivative, the present method invokes the Helmholtz Equation itself to convert derivatives of high order in a single direction into mixed