Applications of Cathodoluminescence of Quartz and Feldspar to Sedimentary Petrology

Cathodoluminescence (CL), the emission of visible light during electron bombardment, was first used in sandstone petrology in the mid-1960\u27s. CL techniques are especially useful for determining the origin and source of quartz and feldspar, two of the most common constituents in elastic rocks. CL properties of both minerals are dependent on their temperature of crystallization, duration of cooling, and/or history of deformation. Detrital quartz and feldspar are typically derived from igneous and metamorphic sources and luminesce in the visible range whereas authigenic quartz and feldspar form at low temperatures and do not luminesce. Quantification of luminescent and non-luminescent quartz and feldspar with the scanning electron microscope, electron microprobe, or a commercial CL device can allow for the determination of origin, diagenesis, and source of elastic rocks when used in conjunction with field and other petrographic analyses. Future expansion and documentation of the classifications and causes of CL in these minerals may increase the usefulness of CL techniques in sandstone petrology

Repetitive Sampling and Control Threshold Improve 16S rRNA Gene Sequencing Results From Produced Waters Associated With Hydraulically Fractured Shale

Sequencing microbial DNA from deep subsurface environments is complicated by a number of issues ranging from contamination to non-reproducible results. Many samples obtained from these environments – which are of great interest due to the potential to stimulate microbial methane generation – contain low biomass. Therefore, samples from these environments are difficult to study as sequencing results can be easily impacted by contamination. In this case, the low amount of sample biomass may be effectively swamped by the contaminating DNA and generate misleading results. Additionally, performing field work in these environments can be difficult, as researchers generally have limited access to and time on site. Therefore, optimizing a sampling plan to produce the best results while collecting the greatest number of samples over a short period of time is ideal. This study aimed to recommend an adequate sampling plan for field researchers obtaining microbial biomass for 16S rRNA gene sequencing, applicable specifically to low biomass oil and gas-producing environments. Forty-nine different samples were collected by filtering specific volumes of produced water from a hydraulically fractured well producing from the Niobrara Shale. Water was collected in two different sampling events 24 h apart. Four to five samples were collected from 11 specific volumes. These samples along with eight different blanks were submitted for analysis. DNA was extracted from each sample, and quantitative polymerase chain reaction (qPCR) and 16S rRNA Illumina MiSeq gene sequencing were performed to determine relative concentrations of biomass and microbial community composition, respectively. The qPCR results varied across sampled volumes, while no discernible trend correlated contamination to volume of water filtered. This suggests that collecting a larger volume of sample may not result in larger biomass concentrations or better representation of a sampled environment. Researchers could prioritize collecting many low volume samples over few high-volume samples. Our results suggest that there also may be variability in the concentration of microbial communities present in produced waters over short (i.e., hours) time scales, which warrants further investigation. Submission of multiple blanks is also vital to determining how contamination or low biomass effects may influence a sample set collected from an unknown environment

The HLA-A*0201-Restricted H-Y Antigen Contains a Posttranslationally Modified Cysteine That Significantly Affects T Cell Recognition.

AbstractA peptide recognized by two cytotoxic T cell clones specific for the human minor histocompatibility antigen H-Y and restricted by HLA-A*0201 was identified. This peptide originates from SMCY, as do two other H-Y epitopes, supporting the importance of this protein as a major source of H-Y determinants in mice and humans. In naturally processed peptides, T cells only recognize posttranslationally altered forms of this peptide that have undergone modification of a cysteine residue in the seventh position. One of these modifications involves attachment of a second cysteine residue via a disulfide bond. This modification has profound effects on T cell recognition and also occurs in other class I MHC-associated peptides, supporting its general importance as an immunological determinant

When using small samples to evaluate hydrocarbon reservoirs, proceed with caution

Small-angle neutron scattering (SANS) and ultra-small angle neutron scattering (USANS) with contrast matching techniques (Melnichenko and others, 2012) were used to investigate size distribution and gas accessibility in pores in an approximately 10.6 cm long Mississippian Barnett Shale butt core from the Fort Worth Basin, Texas, USA. SANS and USANS measurements record scattering from all pores, both open and closed, in the size range 10nm - ~10 μ. The techniques can also be used to determine the material that contains pores and the number of pores as a function of size. By injecting deuterated methane gas (CD4) at contrast matching pressure it is possible to distinguish which pores are accessible, or open, to fluids and which ones are not

Repetitive Sampling and Control Threshold Improve 16S rRNA Gene Sequencing Results From Produced Waters Associated With Hydraulically Fractured Shale

Sequencing microbial DNA from deep subsurface environments is complicated by a number of issues ranging from contamination to non-reproducible results. Many samples obtained from these environments – which are of great interest due to the potential to stimulate microbial methane generation – contain low biomass. Therefore, samples from these environments are difficult to study as sequencing results can be easily impacted by contamination. In this case, the low amount of sample biomass may be effectively swamped by the contaminating DNA and generate misleading results. Additionally, performing field work in these environments can be difficult, as researchers generally have limited access to and time on site. Therefore, optimizing a sampling plan to produce the best results while collecting the greatest number of samples over a short period of time is ideal. This study aimed to recommend an adequate sampling plan for field researchers obtaining microbial biomass for 16S rRNA gene sequencing, applicable specifically to low biomass oil and gas-producing environments. Forty-nine different samples were collected by filtering specific volumes of produced water from a hydraulically fractured well producing from the Niobrara Shale. Water was collected in two different sampling events 24 h apart. Four to five samples were collected from 11 specific volumes. These samples along with eight different blanks were submitted for analysis. DNA was extracted from each sample, and quantitative polymerase chain reaction (qPCR) and 16S rRNA Illumina MiSeq gene sequencing were performed to determine relative concentrations of biomass and microbial community composition, respectively. The qPCR results varied across sampled volumes, while no discernible trend correlated contamination to volume of water filtered. This suggests that collecting a larger volume of sample may not result in larger biomass concentrations or better representation of a sampled environment. Researchers could prioritize collecting many low volume samples over few high-volume samples. Our results suggest that there also may be variability in the concentration of microbial communities present in produced waters over short (i.e., hours) time scales, which warrants further investigation. Submission of multiple blanks is also vital to determining how contamination or low biomass effects may influence a sample set collected from an unknown environment

Migration of Research Results into Operational Monitoring Systems

For the Department of Energy (DOE) Knowledge Base to support activities for monitoring nuclear explosions consistent with eventual verification activities under the Comprehensive Nuclear-Test-Ban Treaty (CTBT), a process is defined to ensure the integrity and utility of research results during the migration into information products for use in operational monitoring systems. The process of validating, verifying, and managing the information products ensures deliveries of high-quality Knowledge Base releases to the United States National Data Center(USNDC). These activities are critical to the successful integration of scientific research to support operational monitoring systems at the USNDC. A by-product of this process is that datasets, or components of information products, that have undergone the validation and verification process maybe distributed as operational calibration products to the International Data Centre. All contributors to information products, whether DOE-funded or not, will benefit from transparency of the integration process to effect successful participation in the process. As an information product passes through the steps necessary to become part of a delivery to the USNDC, domain experts, including the end-users, will provide validation -- a determination of relevance and scientific quality. The integration process continues with verification -- an assessment of completeness and correctness, provided by the Knowledge Base integrator, the information product coordinator, and the contributing organization. The information products and their constituent datasets are systematically tracked through the integration portion of their life cycle (Moore, et al, 2000; Carret al, 2000). Finally, the proposed delivery of the Knowledge Base and its constituent information products is reviewed by an Integration Board. The integration process is presented in this paper, with details described in Moore et al., (2000)