This article discusses scanning tunneling microscopy of the electronic structure of chemical vapor deposited diamond films.

Article discussing the Markov approximation and inconsistency of the standard quantum Brownian motion model.

Article discussing the simultaneous measurement of the average ion-induced electron emission yield and the mean charge for isotachic ions in carbon foils.

Article on the mechanism of strain release in carbon nanotubes.

Article on polycyclic aromatic hydrocarbon solute probes and an evaluation of additional naphthacene and perylene derivatives as possible solvent polarity probe molecules.

Article on the spectroscopic properties of polycyclic aromatic compounds and an examination of nitromethane as a selective fluorescence quenching agent for alternant polycyclic aromatic nitrogen hetero-atom derivatives.

Article discussing auditory cortex neurons and primary culture and ion channel activity in rat.

Article on the solubility of anthracene in ternary 2-alkoxyethanol + cyclohexane + heptane and 2-alkoxyethanol + cyclohexane + 2,2,4-trimethylpentane solvent mixtures.

Article on selective fluorescence quenching to discriminate between alternant and non-alternant polycyclic aromatic hydrocarbons and acephenanthrylene derivatives as exceptions to the nitromethane quenching rule.

Newspaper article about an upcoming Harvey Girls luncheon put on by the Temple, Texas Railroad and Pioneer Museum. The article was sent by Joe W. Zvolanek to Rosa Walston Latimer.

Article on rate coefficients for the hydrogen atom + ammonia reaction over a wide temperature range.

Article on a kinetic study of the recombination reaction sodium + sulfur dioxide + argon.

The tritium breeding blanket is one of the most important components of a fusion reactor because it directly involves both energy extraction and tritium production, both of which are critical to fusion power. Because of their overall desirable properties, lithium-containing ceramic solids are recognized as attractive tritium breeding materials for fusion reactor blankets. Indeed, their inherent thermal stability and chemical inertness are significant safety advantages. In numerous in-pile experiments, these materials have performed well, showing good thermal stability and good tritium release characteristics. Tritium release is particularly facile when an argon or helium purge gas containing hydrogen, typically at levels of about 0.1%, is used. However, the addition of hydrogen to the purge gas imposes a penalty when it comes to recovery of the tritium produced in the blanket. In particular, a large amount of hydrogen in the purge gas will necessitate a large multiple-stage tritium purification unit, which could translate into higher costs. Optimizing tritium release while minimizing the amount of hydrogen necessary in the purge gas requires a deeper understanding of the tritium release process, especially the interactions of hydrogen with the surface of the lithium ceramic. This paper reviews the status of ceramic breeder research and highlights …

We have performed numerical simulations of the transient collisional excitation Ni-like Pd 4d {r_arrow} 4p J = 0 {r_arrow} 1 147 {angstrom} laser transition recently observed at Lawrence Livermore National Laboratory (LLNL). The high gain {approximately}35 cm results from the experiment are compared with detailed modeling simulations from the 1-D RADEX code in order to better understand the main physics issues affecting the measured gain and x-ray laser propagation along the plasma column. Simulations indicate that the transient gain lifetime associated with the short pulse pumping and refraction of the x-ray laser beam out of the gain region are the main detrimental effects. Gain lifetimes of {approximately}7 ps(1/e decay) are inferred from the smoothly changing gain experimental observations and are in good agreement with the simulations. Furthermore, the modeling results indicate the presence of a longer-lived but lower gain later in time associated with the transition from transient to quasi-steady state excitation.

An attempt is made at illustrating the many contributions to rock mechanics from US defense programs, over the past 30-plus years. Large advances have been achieved in the technology-base area covering instrumentation, material properties, physical modeling, constitutive relations and numerical simulations. In the applications field, much progress has been made in understanding and being able to predict rock mass behavior related to underground explosions, cratering, projectile penetration, and defense nuclear waste storage. All these activities stand on their own merit as benefits to national security. But their impact is even broader, because they have found widespread applications in the non-defense sector; to name a few: the prediction of the response of underground structures to major earthquakes, the physics of the earth`s interior at great depths, instrumentation for monitoring mine blasting, thermo-mechanical instrumentation useful for civilian nuclear waste repositories, dynamic properties of earthquake faults, and transient large-strain numerical modeling of geological processes, such as diapirism. There is not pretense that this summary is exhaustive. It is meant to highlight success stories representative of DOE and DOD geotechnical activities, and to point to remaining challenges.

Neptunium has a high solubility in groundwaters from Yucca Mountain [1]. Uranium in nuclear reactors produces {sup 237}Np which has a half-life of 2.1 4 {times} 10{sup 6} years. Consequently, the transport of {sup 237}Np through tuffs is of major importance in assessing the performance of a high-level nuclear waste repository at Yucca Mountain. The objective of this work is to determine the amount of Np retardation that is provided by the minerals in Yucca Mountain tuffs as a function of groundwater chemistry.

Separate abstracts have been prepared for the papers presented at the meeting on nuclear facility air cleaning technology in the following specific areas of interest: air cleaning technologies for the management and disposal of radioactive wastes; Canadian waste management program; radiological health effects models for nuclear power plant accident consequence analysis; filter testing; US standard codes on nuclear air and gas treatment; European community nuclear codes and standards; chemical processing off-gas cleaning; incineration and vitrification; adsorbents; nuclear codes and standards; mathematical modeling techniques; filter technology; safety; containment system venting; and nuclear air cleaning programs around the world. (MB)

Proton and deuteron kinetic energy spectra have been measured at target rapidities for both minimum bias and central collisions of 14.6 A{center_dot}GeV/c {sup 28}Si and 11.7 A{center_dot}GeV/c {sup 197}Au beams with a {sup 197}Au target. The spectra were measured from a low energy threshold of approximately E{sub kin}=35 MeV to well over 200 MeV for laboratory angles of 50{degree} to 130{degree} ({vert_bar}{eta}{vert_bar} {le}0.76). The acceptance-corrected spectra have been fit over a limited range of kinetic energies using a Boltzmann distribution. The integrated yields and the inverse slope parameters are presented as a function of centrality for the {sup 28}Si + {sup 197}Au reaction and as a function of trigger for the {sup 197}Au + {sup 197}Au reaction. These quantities are also compared with the proton spectra generated using both the ARC and RQMD codes.

The US Department of Energy is studying the suitability of Yucca Mountain (YM) as a potential nuclear waste repository site. Environmental conditions are important to engineered barrier system (EBS) design, materials testing, selection, design criteria, waste-form characterization, and performance assessment. Yucca Mountain is located in uninhabited desert which results in an environmental framework (unsaturated conditions, and sorptive properties of the rock materials) that is generally favorable for waste disposal. However, waste package (WP) and engineered barrier system (EBS) design concepts, including materials testing and selection, design criteria development, waste-form characterization, and performance assessments all require a specific and detailed understanding of the environmental conditions that will interact with the WP/EBS. Environmental conditions assessments from a series of laboratory and modeling studies have been conducted which provide the current understanding of the near-field environmental conditions at YM that not only exist now but will exist in the future. Because the environmental conditions can change with time, emphasis of the investigations were on processes and changed (not ambient) conditions.

We present results of molecular dynamics computer simulation studies of the threshold energy for point defect production in silicon. We employ computational cells with 8000 atoms at ambient temperature of 10 K that interact via the Stillinger-Weber potential. Our simulations address the orientation dependence of the defect production threshold as well as the structure and stability of the resulting vacancy-interstitial pairs. Near the <111> directions, a vacancy tetrahedral-interstitial pair is produced for 25 eV recoils. However, at 30 eV recoil energy, the resulting interstitial is found to be the <110> split dumbbell configuration. This Frenkel pair configuration is lower in energy than the former by 1.2 eV. Moreover, upon warming of the sample from 10 K the tetrahedral interstitial converts to a <110> split before finally recombining with the vacancy. Along <100> directions, a vacancy-<110> split interstitial configuration is found at the threshold energy of 22 eV. Near <110> directions, a wide variety of closed replacement chains are found to occur for recoil energies up to 45 eV. At 45 eV, the low energy vacancy-<l 10> split configuration is found. At 300 K, the results are similar. We provide details on the atomic structure and relaxations near these defects as …

In this paper, a linearized four wheel steering (4WS) system model is deduced and then modified into a form which is appropriate for applying Matlab {mu} Toolbox to design robust controller. Several important topics are discussed in detail, such as (1) how to make system set-up match Matlab {mu} Toolbox requirement, (2) how to select weights based on plant`s uncertainty, (3) how to solve controller discretization problem, and (4) how to adjust the system so that the conditions necessary for using a state-space formula to solve H{infinity} optimal (sub-optimal) problem and performing the Matlab {mu} Toolbox D--K iteration procedure are satisfied. Finally simulation results of robust controller and a PID controller are compared.

In recent tests without beam, the Argonne 12 MHz split-coaxial radio-frequency quadruple (RFQ) achieved a cw intervane voltage of more than 100 kV, the design operating voltage for the device. This voltage is sufficient for the RFQ to function as the first stage of a RIB injector for the Argonne Tandem Linear Accelerator System (ATLAS). Previously reported beam dynamics calculations for the structure predict longitudinal emittance growth of only a few keV{center_dot}ns for beams of mass 132 and above with transverse emittance of 0.27 {pi} mm{center_dot}mrad (normalized). Such beam quality is not typical of RFQ devices. The work reported here is preparation for tests with beams of mass up to 132. Beam diagnostic stations are being developed to measure the energy gain and beam quality of heavy ions accelerated by the RFQ using the Dynamitron accelerator facility at the ANL Physics Division as the injector. Beam diagnostic development includes provisions for performing the measurements with both a Si charged-particle detector and an electrostatic energy spectrometer system.

A brief description of the Exploratory Shaft based site characterization testing program for the Yucca Mountain Project of the permanent disposal of high level radioactive waste is briefly described in this paper. Details of the testing program are presented in the DOE-issued Site Characterization Plan. Overview of the current planning process and status of various activities is briefly described. This study will reevaluate the mining method, ESF location and any changes in the ESF testing program. 2 refs., 2 figs., 1 tab.

In listing web sites that are of special interest to the Affordable Comfort community, we will try to categorize sites in six major areas: Green Building Product Directories, Software Tools on the Web, Good Places for Learning, Health and Indoor Environment Information, Important Discussion Groups and E-mail Lists, and Sites of Sites. Since we can not help but leave out a great deal, we invite the reader to contact us for lists of sites that we could not include.