Leonel Lagos

Assessment of the Resistance to Uranium (VI) Exposure by Arthrobacter sp. Isolated from Hanford Site Soil

Production of nuclear fuel has resulted in hazardous waste streams that have contaminated the soil and groundwater. Arthrobacter strains, G975, G968, and G954 were used in the prescreening tests to evaluate their tolerance to UO2 2+ and investigate bacteria-U(VI) interactions under oxidizing pH-neutral conditions. Experiments have shown G975 is the fastest growing and the most uranium tolerant strain that removed about 90% of uranium from growth media. Atomic Force Microscopy images exhibited an irregular surface structure, which perhaps provided a larger surface area for uranium precipitation. The data indicate that aerobic heterotrophic bacteria may offer a solution to sequestering uranium in oxic conditions, which prevail in the vadose zone.

The effect of uranium on bacterial viability and cell surface morphology using atomic force microscopy in the presence of bicarbonate ions.

Past disposal practices at nuclear production facilities have led to the release of liquid waste into the environment creating multiple radionuclide plumes. Microorganisms are known for the ability to interact with radionuclides and impact their mobility in soils and sediments. Gram-positive Arthrobacter sp. are one of the most common bacterial groups in soils and are found in large numbers in subsurface environments contaminated with radionuclides. This study experimentally analyzed changes on the bacteria surface at the nanoscale level after uranium exposure and evaluated the effect of aqueous bicarbonate ions on U(VI) toxicity of a low uranium-tolerant Arthrobacter oxydans strain G968 by investigating changes in adhesion forces and cell dimensions via atomic force microscopy (AFM). Experiments were extended to assess cell viability by the Live/Dead BacLight Bacterial Viability Kit (Molecular Probes) and quantitatively illustrate the effect of uranium exposure in the presence of varying concentrations of bicarbonate ions. AFM and viability studies showed that samples containing bicarbonate were able to withstand uranium toxicity and remained viable. Samples containing no bicarbonate exhibited deformed surfaces and a low height profile, which, in conjunction with viability studies, indicated that the cells were not viable.

Quantification of kinetic rate law parameters of uranium release from sodium autunite as a function of aqueous bicarbonate concentrations

Environmental context Uranium is a key contaminant of concern because of its high persistence in the environment and toxicity to organisms. The bicarbonate ion is an important complexing agent for uranyl ions and one of the main variables affecting its dissolution. Results from this investigation provide rate law parameters for the dissolution kinetics of synthetic sodium autunite that can influence uranium mobility in the subsurface. Abstract Hydrogen carbonate (also known as bicarbonate) is one of the most significant components within the uranium geochemical cycle. In aqueous solutions, bicarbonate forms strong complexes with uranium. As such, aqueous bicarbonate may significantly increase the rate of uranium release from uranium minerals. Quantifying the relationship of aqueous bicarbonate solutions to the rate of uranium release during dissolution is critical to understanding the long-term fate of uranium within the environment. Single-pass flow-through experiments were conducted to estimate the rate of uranium release from Na meta-autunite as a function of bicarbonate solutions (0.0005–0.003M) over the pH range of 6–11 and temperatures of 5–60°C. Consistent with the results of previous investigations, the rate of uranium release from sodium autunite exhibited minimal dependency on temperature, but was strongly dependent on pH and increasing concentrations of bicarbonate solutions. Most notably at pH 7, the rate of uranium release exhibited a 370-fold increase relative to the rate of uranium release in the absence of bicarbonate. However, the effect of increasing concentrations of bicarbonate solutions on the release of uranium was significantly less under higher pH conditions. It is postulated that at high pH values, surface sites are saturated with carbonate, thus the addition of more bicarbonate would have less effect on uranium release. Results indicate that the activation energies were unaffected by temperature and bicarbonate concentration variations, but were strongly dependent on pH conditions. As the pH increased from 6 to 11, the activation energy values were observed to decrease from 29.94 to 13.07kJmol–1. The calculated activation energies suggest a surface controlled dissolution mechanism.

Evaluating the role of re-adsorption of dissolved Hg(2+) during cinnabar dissolution using isotope tracer technique.

Cinnabar dissolution is an important factor controlling mercury (Hg) cycling. Recent studies have suggested the co-occurrence of re-adsorption of the released Hg during the course of cinnabar dissolution. However, there is a lack of feasible techniques that can quantitatively assess the amount of Hg re-adsorbed on cinnabar when investigating cinnabar dissolution. In this study, a new method, based on isotope tracing and dilution techniques, was developed to study the role of Hg re-adsorption in cinnabar dissolution. The developed method includes two key components: (1) accurate measurement of both released and spiked Hg in aqueous phase and (2) estimation of re-adsorbed Hg on cinnabar surface via the reduction in spiked (202)Hg(2+). By adopting the developed method, it was found that the released Hg for trials purged with oxygen could reach several hundred μgL(-1), while no significant cinnabar dissolution was detected under anaerobic condition. Cinnabar dissolution rate when considering Hg re-adsorption was approximately 2 times the value calculated solely with the Hg detected in the aqueous phase. These results suggest that ignoring the Hg re-adsorption process can significantly underestimate the importance of cinnabar dissolution, highlighting the necessity of applying the developed method in future cinnabar dissolution studies.

Machine Learning Approach for Malware Detection Using Random Forest Classifier on Process List Data Structure

As computer systems have become an integral part of every organization, it is a big challenge to safeguard the computer systems from malicious activities which compromise not only the systems but also the data stored within. Traditional malware and rootkit detection using antivirus systems are not dynamic enough to capture the complex behavior of malware and its isolated activities. There are many signature-based malware detection techniques have been introduced, but enterprises as well as general users are still facing problems to get protection for their cyber systems against malware. Thus, it emphasizes the necessity of developing an efficient malware detection technique. In this research paper, we design a machine learning approach for malware detection using Random Forest classifier for the process list data extracted from Linux based virtual machine environment.

Design of Virtualization Framework to Detect Cyber Threats in Linux Environment

In todays software and systems environments, security frameworks and models are evolving exponentially. Many traditional host-based frameworks are currently available to detect cyber threats in Linux environment. But there have been many challenges in detecting rootkits that modify the Linux Operating System (OS) kernel to avoid detection. These limitations have lead us to design a virtualization framework for detection of cyber threats in Linux environment. Instead of relying on the Linux Operating System kernel which is now a common victim of cyber-attacks, this virtualization framework will rely on the virtual machine hypervisor which is a more secure software layer that runs the OS kernel and the hardware. The paper proposed a virtualization framework based on well-known hypervisors, to detect cyber threats. The proposed work allowed for a more robust cyber threat detection method than traditional host-based frameworks. It can also possess self-healing properties since it will not only detect compromised servers but also suspend their operation by replacing them with uncompromised versions. This innovative framework promises to secure large scale IT infrastructure with minimum maintenance cost.

The DOE Fellows Program: A Workforce Development Initiative for the US Department of Energy

The US Department of Energy Office of Environmental Management (DOE-EM) oversees one of the largest and most technically challenging cleanup programs in the world. The mission of DOE-EM is to complete the safe cleanup of the environmental legacy from five decades of nuclearweapons development and government-sponsored nuclear energy research. Since 1995, Florida International University’s Applied Research Center (FIU-ARC) has supported the DOE-EM mission and provided unique research capabilities to address some of these highly technical and difficult challenges. This partnership has allowed FIU-ARC to create a unique infrastructure that is critical for the training and mentoring of science, technology, engineering, and math (STEM) students and has exposed many STEM students to “hands-on” DOE-EM applied research, supervised by the scientists and engineers at ARC. As a result of this successful partnership between DOE and FIU, DOE requested FIU-ARC to create the DOE-FIU Science and Technology Workforce Development Initiative in 2007. This innovative program was established to create a “pipeline” of minority STEM students trained and mentored to enter DOE’s environmental cleanup workforce. The program was designed to help address DOE’s future workforce needs by partnering with academic, government and private companies (DOE contractors) to mentor future minority scientists and engineers in the research, development, and deployment of new technologies and processes addressing DOE’s environmental cleanup challenges. Since its inception in 2007, the program has trained and mentored 78 FIU STEM minority students. Although, the program has been in existence for only six years, a total of 75 internships have been conducted at DOE National Laboratories, DOE sites, DOE Headquarters and field offices, and DOE contractors. Over 100 DOE Fellows have participated in the Waste Management (WM) Symposia since 2008 with a total of 84 student posters and 7 oral presentations given at WM. The DOE Fellows participation at WM has resulted in three Best Student Poster Awards (WM09, WM10, and WM11) and one Best Professional Poster Award (WM09). DOE Fellows have also presented their research at ANS DD&R and ANS Robotics Topical meetings and this year two Fellows will present at the International Conference on Environmental Remediation and Radioactive Waste Management (ICEM13) in Brussels, Belgium. Moreover, several of our DOE Fellows have already obtained employment with DOE-EM, other federal agencies, DOE contractors, commercial nuclear power companies, and other STEM industry (GE, Boeing, Lockheed Martin, Johnson & Johnson, Beckman-Coulter, and other top companies). This paper will discuss how DOE Fellows program is training and mentoring FIU STEM students in Department of Energy’s Office of Environmental Management technical challenges and research. This training and mentoring has resulted in the development of well-trained and polished young scientists and engineers that will become the future workforce in charge of carrying on DOE-EM’s environmental cleanup mission. The paper will showcase FIU’s DOE Fellows model and highlight some of the applied research the DOE Fellows have conducted at FIU’s Applied Research Center and across the DOE Complex by participating in summer internship assignments.Copyright

D&D Knowledge Management Information Tool: A Web Based System Developed to Share D&D Knowledge Worldwide

Deactivation and decommissioning (D&D) work is a high-risk and technically challenging enterprise within the U.S. Department of Energy complex. During the past three decades, the DOE’s Office of Environmental Management has been in charge of carrying out one of the largest environmental restoration efforts in the world: the cleanup of the Manhattan Project legacy.In today’s corporate world, worker experiences and knowledge that have developed over time represent a valuable corporate asset. The ever-dynamic workplace, coupled with an aging workforce, presents corporations with the ongoing challenge of preserving work-related experiences and knowledge for cross-generational knowledge transfer to the future workforce [5]. To prevent the D&D knowledge base and expertise from being lost over time, the DOE and the Applied Research Center at Florida International University (FIU) have developed the web-based Knowledge Management Information Tool (KM-IT) to capture and maintain this valuable information in a universally available and easily accessible and usable system. The D&D KM-IT was developed in collaboration with DOE Headquarters (HQ), the Energy Facility Contractors Group (EFCOG), and the ALARA [as low as reasonably achievable] Centers at Savannah River Sites to preserve the D&D information generated and collected by the D&D community. This is an open secured system that can be accessed from https://www.dndkm.org over the web and through mobile devices at https://m.dndkm.org.This knowledge system serves as a centralized repository and provides a common interface for D&D-related activities. It also improves efficiency by reducing the need to rediscover knowledge and promotes the reuse of existing knowledge. It is a community-driven system that facilitates the gathering, analyzing, storing, and sharing of knowledge and information within the D&D community. It assists the DOE D&D community in identifying potential solutions to their problem areas by using the vast resources and knowledge base available throughout the global D&D community.The D&D KM-IT offers a mechanism to the global D&D community for searching relevant D&D information and is focused on providing a single point of access into the collective knowledge base of the D&D community within and outside of the DOE. Collecting information from subject matter specialists, it builds a knowledge repository for future reference archiving Lessons Learned, Best Practices, ALARA reports, and other relevant documents and maintains a secured collaboration platform for the global D&D community to share knowledge. With the dynamic nature and evolution of the D&D knowledge base due to multiple factors such as changes in the workforce, new technologies and methodologies, economics, and regulations, the D&D KM-IT is being developed in a phased and modular fashion.Copyright