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Student
Abstracts at LLNL:
Analysis of a Microbial Biofilm Matrix. ANNA SIEBERS
(University of California, San
Diego, La Jolla, CA, 92093)
MICHAEL P. THELEN (Lawrence Livermore
National Laboratory, Livermore, CA, 94550)
A matrix comprised
of cells and polymeric substance distinguishes a robust biofilm found
floating in extremely acidic waters of an iron mine in northern California.
Although both components are integral to the biofilm, the extracellular
polymeric substance (EPS) has not been characterized and its function
in the biofilm is poorly understood. To isolate the EPS, biofilm
samples were disrupted and washed with dilute sulfuric acid. EPS
could then be precipitated from the acid wash with either ammonium
sulfate or ethanol. This gelatinous material was analyzed using a
variety of independent techniques, including solvent treatment, UV-visible
spectroscopy, gel electrophoresis, elemental analysis, and glycosyl
analysis (in progress). EPS was not soluble in 17.5% NaOH, indicating
a cellulosic component, and dissolved completely in 2M HCl. Analysis
of material precipitated with 15, 30, 60 and 75% ethanol indicated
differential sedimentation, with EPS primarily in the 15 and 30%
fractions. Denaturing polyacrylamide gel electrophoresis of these
fractions revealed two proteins with molecular weights of ~20 kDa
and 60 kDa exclusively in the 60% fraction. Also, DNA was found in
the same fraction using agarose gel electrophoresis; this was corroborated
by a distinct absorbance peak at 260 nm. Elemental analysis of the
total EPS material
indicated a chemical
formula of C18H35O17N2S,
consistent with a polysaccharide assignment (1:2:1 CHO). Glycosyl analysis following
pyrolysis, gas chromatography and mass spectrometry will determine the carbohydrate
composition of the EPS and will give insight into its electronic charge state
and hydrophobicity, and perhaps explain the buoyancy of the biofilm. We propose
that the EPS protects the microbial community by buffering the acidity of the
mine water and facilitating the exchange of gases at the air-water interface.
Therefore, understanding the role of EPS within the biofilm will lead to further
characterization of this unique microbial system and help determine how the community
thrives in such
an extreme environment.
Analyzing the Structure and Function of Novel Cytochromes from a Natural Microbial
Community. ANNA SIEBERS (University
of California, San
Diego, La Jolla, CA, 92093)
MICHAEL P. THELEN (Lawrence Livermore
National Laboratory, Livermore, CA, 94550)
The Richmond mine in Iron
Mountain, California, provides an unusual ecosystem suitable for the
growth of microbial biofilms which produce many unique proteins. Through
iron oxidation, these proteins facilitate acid mine drainage (AMD).
Because this habitat is extremely acidic, survival is an extraordinary
feat and the process of environmental selection is rare. In order to
understand the mechanisms by which these organisms oxidize iron and
gain electrons for energy, biochemical studies were applied. More specifically,
column chromatography, spectrophotometry, and gel electrophoresis were
used to determine the proteins present in different biofilms. Two specific
locations of the mine researched were the AB drift and Ultraback C
(UBC), which were both found to contain at least five different types
of protein and a large amount of heme-bound cytochromes. Another application
of these methods was to investigate proteins playing a major role within
the
community; one protein selected was cytochrome 579 (Cyt579) due to its abundance in the biofilm, iron oxidizing potential,
and signature absorbance of 579nm. The structure and function of Cyt579 could
be characterized by the isolation of its heme, which was completed using column
chromatography; however, one of the challenges has been liberating the heme from
the column. Further research, including acid-base and temperature profiling of
Cyt579 should help elucidate its structural changes within alternate
environments and metabolism within the community.
Criticality Evaluation of Plutonium-239 Moderated by High-Density Polyethylene
in Stainless Steel and Aluminum Containers Suitable for Non-Exclusive
Use Transport. TIMOTHY WATSON (Rensselaer Polytechnic Institute, Troy, NY, 12180)
JOHN SCORBY (Lawrence Livermore
National Laboratory, Livermore, CA, 94550)
Research is conducted
at the Joint Actinide Shock Physics Experimental Facility (JASPER) on the
effects of high pressure and temperature environments on 239Pu, in support
of the stockpile stewardship program. Once an experiment has been completed,
it is necessary to transport the end products for interim storage or final
disposition. Federal shipping regulations for non-exclusive use transportation
have an exemption allowance when no more than 180 grams of fissile material
are present in at least 360 kilograms of contiguous non-fissile material.
This allowance exempts the shipper from the requirement to establish and
assign a Criticality Safety Index for a package. To evaluate the general
applicability and conservatism of this exemption criterion, a worst-case
scenario of 180g 239Pu was modeled using one of Lawrence Livermore National
Laboratory’s in-house Monte Carlo transport codes known as COG 10. The geometry
consisted of 239Pu spheres homogenously mixed with high-density polyethylene
surrounded by a cube of either stainless steel 304 or aluminum. An optimized
geometry for both cube materials and hydrogen-to-fissile isotope (H/X) ratio
were determined for a single unit. Infinite and finite 3D arrays of these
optimized units were then simulated to determine if the systems would exceed
criticality. Completion of these simulations showed that the optimal H/X
ratio for the most reactive units ranged from 800 to 1600. A single unit
of either cube material would not reach criticality. An infinite array was
determined to reach criticality. A lower loading of 100g of 239Pu was then
considered and found to be subcritical in an infinite array with either Al
or steel. The offsetting of spheres in their respective cubes was also simulated
and showed a considerable decrease in the number of close-packed units needed
to reach criticality. These results call into question the general applicability
of current regulations for fissile material transport, which under the modeled
circumstances may not be sufficient in preventing a critical system. However,
a conservative approach was taken in all assumptions and such idealized configurations
would most likely not be achieved in more realistic loadings. Additional
modeling should be conducted to verify these findings to ensure the transportation
requirements are appropriately
conservative.
Determination of Naturally Occurring versus Process Introduced Beryllium at Lawrence Livermore National Laboratory. JENNIFER MULLINS (Randolph-Macon Woman's College, Lynchburg, VA, 24503) RYAN KAMERZELL (Lawrence Livermore
National Laboratory, Livermore, CA, 94550)
The Department of Energy
(DOE) Title
10 Code of Federal Regulations, Part 850, Chronic Beryllium
Disease Prevention Program defines
the maximum removable surface contamination of beryllium (Be) in non-Be work
areas as the
higher of 0.2 µg Be/100cm2 or the concentration of Be in soil at the point of release.
Be is a naturally occurring metal and can be found on surfaces in concentrations
greater than the defined DOE release limit without a process present that would
introduce contamination. Until now there has been no standardized method for
deciphering between naturally occurring and process introduced Be. The purpose
of this research was to develop such a method by determining naturally occurring
ratios of Be to other naturally occurring metals in soil at Lawrence Livermore
National Laboratory (LLNL). Sixty random soil samples were collected from uncontaminated
locations within the LLNL site boundary. The samples were analyzed for the concentrations
of Be and 19 other metals using an Inductively Coupled Plasma Spectrometer. Aluminum
(Al), nickel (Ni), and vanadium (V) were selected to calculate the naturally
occurring ratios based upon detection rates, low variability, and R-values from
the Ryan-Joiner W-test for normality. Two-sided 95% upper and lower tolerance
limits (UTL and LTL) were calculated for the true 95th percentile of each naturally occurring ratio: [Be]:[Al]- UTL97.5%,95% =5.06x10-5,
LTL2.5%,95%=4.35x10-5,
mean=3.40x10 -5;
[Be]:[Ni]- UTL97.5%,95%=1.73x10-2,
LTL2.5%,95%=1.30x10-2,
mean=8.12x10-3;
and [Be]:[V]- UTL97.5%,95%=1.63x10-2,
LTL2.5%,95% =1.38x10-2,
mean=1.05x10-2.
Sample data suggests with 95% confidence that 95% of the ratios do not exceed
the true UTL when beryllium is naturally occurring. Future data can be compared
to the ratios to conclude the following: (1) if the sample ratio is less than
the LTL, the Be is naturally occurring, (2) if the sample ratio is greater than
the LTL but less than the UTL, further investigation is required, and (3) if
the sample ratio is greater than the UTL, the Be is process introduced. Other
DOE sites can use this method to determine their own ratios to discriminate between
naturally occurring and process introduced Be. The ability to determine this
will allow for redirection of resources away from unnecessarily implementing
decontamination requirements for cleaning surfaces with false contamination.
Implementing this method would be fiscally responsible while not increasing employee
health risk.
Electrolysis and Pressure Driven Flow for Temperature Gradient Focusing. ELLIS GARAI (University of California, Los
Angeles, Los Angeles, CA, 90095)
KEVIN NESS (Lawrence Livermore
National Laboratory, Livermore, CA, 94550)
Bio-warfare detection systems
are a necessary means of maintaining national security. In order for a detection
system to be practical and largely deployed it should be easy to use, affordable,
portable, low power, rapid, accurate, and autonomous. Currently, bio-warfare
detection instrumentation do not meet the aforementioned specifications due to
the lack of automated front-end sample preparation(FESP). FESP consists of purifying,
concentrating, and separating ‘complex’ environmental samples in order to improve
the downstream detection assays performance. Temperature gradient focusing(TGF)
has been identified as a novel microfluidic technique to aid in the necessary
autonomous FESP. TGF is the balance of an advective flux and an electrophoretic
flux, in the presence of a temperature gradient, to ensure focusing only occurs
at a unique spatial location along the axis of the microchannel. The main factors
influencing the stability during TGF are a stable flow field and a stable electric
field within the microfluidic system; therefore, these parameters must be tightly
controlled. Electrolysis greatly influences these parameters; any gas formation
within a channel can perturb both the flow and at the very least perturb the
electric field. An in-line gas management system was devised to overcome this
obstacle. Several approaches were taken to address this issue. The first was
to remove the gas forming at the electrode through a porous gas permeable Teflon
material while under vacuum. The second consisted of a large sealed air/liquid
electrode reservoir, through which bubbles would float to the surface. With certain
disadvantages in the first two, a final, more promising approach to directly
isolate the gas formation was chosen. By using a proton permissible material
(Nafion), gas generated at the electrode is isolated from the TGF flow line and
swept down a separate line using a constant running buffer. In addition to electrolysis
altering the flow field, generating a stable flow at the ~100 nL/min range was
another hurdle. Commercial pumping technology has an ~10% variation in the flow
rate at any given time. By using a high resolution flow sensor and a dynamically
controlled pressure source, in combination with a custom PID control scheme,
a stable flow rate of less than 1% change (~ 1 nL/min) was attained. Through
this tighter control over important TGF parameters improvements in purification,
separation, and concentration effects are realized.
Evaluation and Recommendation of Advanced Laser Power and Laser Energy Meters
for Potential Acquisition. TIMOTHY
CHEERS (Southwest Tennessee Community College, Memphis, TN, 38134)
MARK LUDWIG (Lawrence Livermore
National Laboratory, Livermore, CA, 94550)
Lasers are powerful research
tools but pose significant safety issues if not monitored and controlled appropriately.
The ever evolving world of technology has developed smaller, more advanced meters
used to monitor power-energy emissions from lasers. These devices are called
laser power and laser energy meters. The Hazards Control Department (HCD) uses
power and energy meters to verify output of lasers, reclassify lasers as needed,
and conduct accident investigations should one occur. Due to their safety applications,
the HCD power-energy meters are calibrated to National Institute of Science and
Technology standards and are an integral component of Lawrence Livermore National
Laboratory’s (LLNL) laser safety program. LLNL HCD has not updated these meters
for many years. The purchase
of updated equipment would enhance HCD’s capability and efficiency in supporting
LLNL laser users in the performance of critical laser measurements. The newer
more advanced power-energy meters were researched and companies solicited for
loaner units. A test plan and meter rating spreadsheet tool was developed for
evaluating the instruments based on their capability to meet LLNL laser system
performance needs (e.g., maximum power-energy levels, total range, pulse width,
and laser repetition rate). The usability factors as determined by the researchers,
compatibility with LLNL data transfer devices, cost, maintenance and calibration
requirements, performance history at other facilities, etc. were taken into account.
Three companies arranged to loan units for LLNL’s evaluation. Limited testing
with researchers was completed on the units received. Based on the rating results
and budget constraints, a single laser power and energy meter was selected. Using
this rating spreadsheet, selecting the most suitable meter has become a more
efficient and valid process, which will be useful for future meter evaluations.
This work was performed under the auspices of the U.S. Department of Energy by
University of California, Lawrence Livermore National Laboratory under Contract
W-7405-Eng-48.
Evaluation of Compliance with Safe Standard Practices and Uses of Class II
Biological Safety Cabinets Used in Biosafety Level 2 Laboratories. PETER
HOANG (Dominican University of California, San
Rafael, CA, 94901) LESLIE
A. HOFHERR (Lawrence Livermore
National Laboratory, Livermore, CA, 94550)
Biosafety Level 2 (BSL-2)
laboratories contain operations involving biological risk agents such as infectious
microorganisms associated with various human diseases that are of moderate potential
hazard to lab personnel and the environment. When working with these agents,
there is a risk from aerosol or splash production of biohazardous materials that
can contaminate laboratory personnel, their work area, and the environment. Safety
regulations, requirements, and guidelines developed by the Center for Disease
Control & Prevention (CDC) and the National Institute of Health (NIH) recommend
the use of physical containment devices to help minimize such exposure during
BSL-2 operations. Biological safety cabinets (BSC) are one of the most effective
primary barriers for such hazards. Based on these national documents along with
the biosafety requirements and guidelines contained in the Lawrence Livermore
National Laboratory (LLNL) Environmental Safety and Health
Manual (ES&HM), a compliance survey was created to assess how well LLNL personnel
implement appropriate BSC safety etiquette and procedures. The survey’s questions
consisted of topics chosen at the discretion of the surveyor. Eight researchers
from eight of the forty-seven LLNL BSL-2 facilities were interviewed and their
operations and workplaces were evaluated. All eight of the operations reviewed
in this assessment had at least one or more practices or controls that deviated
from the guidelines or requirements stated in the LLNL and national safety documents
of both the CDC and NIH. The most common issues identified included improper
personal protective equipment (PPE) decontamination and disposal, lack of maintenance
of the ultraviolet lamp, lack of a proper sharps container inside the BSC, lack
of procedure for checking airflow, and lack of High Efficiency Particulate Air
(HEPA) filter maintenance. The findings of this survey indicate that enhanced
worker training and additional assurance evaluations along with more detailed
guidelines in the ES&HM may be warranted. The survey results in the areas
of decontamination and maintenance may serve to guide more detailed assessments
in the future to identify additional actions that may help improve BSL-2 safety
practices and procedures while using a BSC. This work was performed under the
auspices of the U.S. Department of Energy by University of California, Lawrence
Livermore National Laboratory under Contract W-7405-Eng-48.
Lifecycle Determination for Industrial Hygiene Portable Safety Equipment. JORDAN KLINGSPORN (University
of Wisconsin - Green Bay, Green
Bay, WI, 54311) GORDON
MILLER (Lawrence Livermore National
Laboratory, Livermore, CA, 94550)
A policy for industrial hygiene
instrument lifecycle assessment is necessary to ensure quality equipment is maintained,
sufficient instrument capability is provided, and maintenance and replacement
costs are not excessive. Such a policy is needed to ensure laboratory resources
are optimized during times of increasing fiscal constraints and high regulatory
scrutiny. While formalized lifecycle assessment guidance and strategies are common
for facility structures, capital equipment, and consumer products such as automobiles,
home electronics, and appliances, such guidance is not readily available for
smaller scale equipment such as portable safety instrumentation. A combination
quantitative and qualitative approach was investigated to develop a defensible
and transparent basis for performing lifecycle assessments to support an industrial
hygiene instrument replacement policy. Several factors were compiled to aid in
predicting the lifetime of an instrument using instrument performance history
reviews, operational conditions, recommendations from manufacturers, and feedback
from equipment users throughout the Department of Energy complex. Some of the
primary factors that were found to impact instrument lifetime are: changes in
equipment technology, cost effectiveness of replacement compared to repair, availability
of parts and factory calibration services, total cost of replacement, performance
history, and equipment replacement costs being justified by increased efficiency
and/or capability. Utilizing the compiled data, a spreadsheet tool was developed
to apply the lifetime factors to prioritizing current instrumentation for replacement,
as well as determine longer-term replacement budget strategies. The instrument
lifetime factors and policy developed by this effort were nominally intended
for portable industrial hygiene instrumentation, but they could be readily applied
to instruments with different functions. The Lawrence Livermore National Laboratory
Industrial Hygiene Instrument Laboratory will use these factors, tools, and policy
drafted by this research as part of their operational strategy to help ensure
quality safety equipment is maintained while minimizing costs. This work was
performed under the auspices of the U.S. Department of Energy by University of
California, Lawrence Livermore National Laboratory under Contract W-7405-Eng-48.
UCRL-ABS-233244
Modeling Estimated Personnel Needs for a Potential Foot and Mouth Disease Outbreak. KIRSTEN SIMMONS (North Carolina State University, Raleigh, NC, 27607)
DR. PAM HULLINGER (Lawrence Livermore
National Laboratory, Livermore, CA, 94550)
Foot and Mouth disease (FMD) is a highly
contagious viral disease affecting livestock that was last detected in the US
in 1929. The prevalence of FMD in other countries, as well as the current potential
for this virus to be used as a form of agroterrorism has made preparations for
a potential FMD outbreak a national priority. All 50 states were surveyed via
e-mail, telephone and web search to obtain emergency response plans for FMD or
for foreign animal diseases in general. Information from 35 states was obtained
and analyzed for estimates of resources needed to respond to an outbreak. These
estimates were expanded and enhanced to create a spreadsheet tool that could
be used by individual states to better understand the personnel that would be
needed to complete various tasks during an outbreak response. Personnel estimates
were varied according to facility type and scaled by size. The estimates were
then coupled to the output from FMD outbreaks simulated using the Multiscale
Epidemiological/Economic Simulation and Analysis (MESA) model at Lawrence Livermore
National Laboratory to assess the personnel resource demands on a response agency
over the course of an outbreak response.
Simulation of Electron Trajectories Inside an Annular Dielectric. JULIE MANAGAN (Vanderbilt University, Nashville, TN, 37235) JOHN R. HARRIS (Lawrence Livermore
National Laboratory, Livermore, CA, 94550)
Development of a compact
Dielectric Wall Accelerator (DWA) is desirable for scientific and medical applications
such
as proton therapy, but requires vacuum insulators to withstand electric fields
(E-field) near 100-MV/m without surface flashover. It is believed that flashover
is caused by secondary electron emission avalanches (SEEA), requiring field-emitted
electrons to re-strike the insulator surface. In a fast voltage pulse, changing
E-field creates a displacement current and induces a magnetic field (B-field),
which will influence the trajectories of field-emitted electrons. This may cause
them to strike the insulator, triggering SEEA. In a previous study, B-field simulations
showed this effect for particles emitted from the exterior of a cylindrical dielectric.
This abstract describes a study simulating the B-field effect on electrons emitted
from the interior of an annular dielectric capped by disc electrodes. The particle-in-cell
code LSP was used to simulate field-emitted electrons under the E and B-fields
created on the rising edge of a trapezoidal voltage pulse, while varying outer
diameter, inner diameter, dielectric constant, emission time, voltage pulse length,
and emission energy. Since conventional flashover research does not account for
B-field effects due to displacement current, the code was modified so that the
B-field could be eliminated, and all tests were run with and without it. The
sign and strength of the B-field determined particle motion: when the E-field
had a positive rate of change the B-field deflected electrons away from the surface,
but when it had a negative rate of change the B-field deflected electrons toward
the surface. Ringing appeared at the end of the voltage ramp, creating a negative
rate of change in the E-field. Variations in timing and geometry influenced the
fields seen by the particles and changed their trajectories accordingly. Where
no B-field was present, the electrons traveled within 1mm of the surface. Under
most conditions, the B-field deflected electrons away from the interior surface
during the rising edge of the voltage pulse, which is opposite to its effect
on the exterior surface. This benefits the DWA system by decreasing possible
triggers of SEEA. This study improved understanding of vacuum insulators, and
will aid development of materials that are better suited to the high E-fields
of the DWA.
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