PROPERTY SENSITIVITY STUDY FOR OIL RECOVERY IN THE BAKKEN

The upstream (exploration and production) end of the petroleum industry has experienced tremendous success over the past fifteen years by employing innovative ways to drill and stimulate new wells thereby greatly increasing production. Based upon these successes, there has been a shift to unconventional wells, where the cost for drilling and completing wells can be much more expensive. Most unconventional wells target tight rock formations having low permeability and porosity. As a result, these reservoirs require enhanced stimulation to improve recovery operations to establish profitable oil or gas production. These wells are drilled horizontally to maximize contact area in the zone of interest and generally need to be hydraulically fractured to stimulate and enhance production. Additional research is needed to better understand the nature of tight reservoirs such as the Bakken, and to provide for better reservoir modeling, simulation, and enhanced hydrocarbon recovery. Wells producing from unconventional reservoirs may not allow for traditional methods of reservoir evaluation due to their unique reservoir properties. Most of these hydrocarbon reservoirs are under sampled and poorly understood. There are comparatively few logs and cores available from unconventional wells. As a result, it is difficult to find relevant lab experiments or data including relative permeability measurements. It is also difficult to obtain representative fluid samples; thus, adding to the difficulty of properly modeling tight resource-play reservoirs. Finally, there are many people building models of unconventional reservoirs, but because of their lack of specific information, their data inputs are uncertain. Therefore, there is a need to investigate how these different parameters affect the results from the various models. Using the Bakken as the formation of investigation, a square mile section is used to analyze the impact of each property. A black oil model and solvent model were built to represent primary recovery and gas injection. Porosity, permeability, relative permeabilities and capillary pressure were the main properties investigated. A dual permeability model was compared to a single permeability model. An equation was found to relate the two models when the models had a well with no hydraulic fractures. Hydraulic fractures were then added to see if this equation could work but was unsuccessful. Results found that, along with porosity and permeability, relative permeabilities can influence a reservoir greatly. The production totals as well as shape of the production curve are affected by relative permeability. This can be used to help improve modeling in unconventional reservoirs and narrow down values for relative permeability

Engage Me: Using New Literacies to Create Third Space Classrooms that Engage Student Writers

Adolescents use a wide variety of literacy practices in their daily lives. Preservice teachers in this study looked for ways to motivate their students to write by asking them about their in-school and out-of-school writing practices. This survey shows a gap between what motivates students to write for school and why they write out of school. The results suggest that English teachers can forge a “third space” in which out-of-school literacy practices are integrated into the curriculum. This survey provides insights for improving writing pedagogy in regards to students’ expressed desire to communicate, express themselves, and to be involved

Voltage control of magnetic order in RKKY coupled multilayers

In the field of antiferromagnetic (AFM) spintronics, there is a substantial effort present to make AFMs viable active components for efficient and fast devices. Typically, this is done by manipulating the AFM Néel vector. Here, we establish a method of enabling AFM active components by directly controlling the magnetic order. We show that magneto-ionic gating of hydrogen enables dynamic control of the Ruderman-Kittel-Kasuya-Yosida (RKKY) interaction in solid-state synthetic AFM multilayer devices. Using a gate voltage, we tune the RKKY interaction to drive continuous transitions from AFM to FM and vice versa. The switching is submillisecond at room temperature and fully reversible. We validate the utility of this method by demonstrating that magneto-ionic gating of the RKKY interaction allows for 180° field-free deterministic switching. This dynamic method of controlling a fundamental exchange interaction can engender the manipulation of a broader array of spin textures, e.g., chiral domain walls and skyrmions

Design and Assessment of Species-Level qPCR Primers Targeting Comammox

Published PCR primers targeting the ammonia monooxygenase gene (amoA) were applied to samples from activated sludge systems operated with low dissolved oxygen (DO) to quantify total and clade-level Nitrospira that perform complete ammonium oxidation (comammox); however, we found these existing primers resulted in significant artifact-associated non-target amplification. This not only overestimated comammox amoA copies but also resulted in numerous false positive detections in the environmental samples tested, as confirmed by gel electrophoresis. Therefore, instead of attempting to quantify comammox diversity, we focused on accurately quantifying the candidate comammox species. We designed specific and sensitive primers targeting 3 candidate species: Candidatus (Ca.) Nitrospira nitrosa, Ca. N. inopinata, and Ca. N. nitrificans. The primers were tested with amoA templates of these candidate species and used to quantify comammox at the species level in low DO activated sludge systems. We found that comammox related to Ca. N. nitrosa were present and abundant in the majority of samples from low DO bioreactors and were not detected in samples from a high DO system. In addition, the greatest abundance of Ca. N. nitrosa was found in bioreactors operated with a long solids retention time. Ca. N. inopinata and Ca. N. nitrificans were only detected sporadically in these samples, indicating a minor role of these comammox in nitrification under low DO conditions

Association of Maternal Immunity with Rotavirus Vaccine Immunogenicity in Zambian Infants

IntroductionLive attenuated oral vaccines against rotavirus (RV) have been shown to be less efficacious in children from developing countries. Reasons for this disparity are not fully understood. We assessed the role of maternal factors including breast milk RV-specific IgA, transplacentally acquired infant serum RV-specific IgG and maternal HIV status in seroconversion among Zambian infants routinely immunized with Rotarix™ (RV1).Methods420 mother-child pairs were recruited at infant age 6–12 weeks in Lusaka. Clinical information and samples were collected at baseline and at one month following the second dose of RV1. Determination of breast milk RV-specific IgA and serum RV-specific IgA and IgG was done using standardized ELISA. Seroconversion was defined as a ≥ 4 fold rise in serum IgA titre from baseline to one-month post RV1 dose 2, while seropositivity of IgA was defined as serum titre ≥ 40 and antibody variables were modelled on log-base 2. Logistic regression was used to identify predictors of the odds of seroconversion.ResultsBaseline infant seropositivity was 25.5% (91/357). The seroconversion frequency was 60.2% (130/216). Infants who were IgA seropositive at baseline were less likely to seroconvert compared to their seronegative counterparts (P = 0.04). There was no evidence of an association between maternal HIV status and seroconversion (P = 0.25). Higher titres of breast milk rotavirus-specific IgA were associated with a lower frequency of seroconverson (Nonparametric test for trend Z = -2.84; P<0.01): a two-fold increase in breast milk RV-specific IgA titres was associated with a 22% lower odds of seroconversion (OR = 0.80; 95% CI = 0.68–0.94; P = 0.01). There was seasonal variation in baseline breast milk rotavirus-specific IgA titres, with significantly higher GMTs during the cold dry months (P = 0.01).ConclusionLow immunogenicity of RV1 vaccine could be explained in part by exposure to high antibody titres in breast milk and early exposure to wild-type rotavirus infections. Potential interference of anti-RV specific IgA in breast milk and pre-vaccination serum RV specific-IgA and IgG titres with RV1 seroconversion and effectiveness requires further research

Structural and chemical characterization of the back contact region in high efficiency CdTe solar cells

Cadmium telluride (CdTe) is the leading commercialized thin-film photovoltaic technology. Copper is commonly used in back contacts to obtain high efficiency, but has also been implicated as a harmful factor for device stability. T hus it is critical to understand its composition and distribution within complete devices. In this work the composition and structure of the back contact region was examined in high efficiency devices (-16%) contacted using a ZnTe:Cu buffer layer followed by gold metallization. T he microstructure was examined in the asdeposited state and after rapid thermal processing (RTP) using high resolution transmission electron microscopy and EDX chemical mapping. After RTP the ZnTe exhibits a bilayer structure with polycrystalline, twinned grains adjacent to Au and an amorphous region adjacent to CdTe characterized by extensive Cd-Zn interdiffusion. T he copper that is co-deposited uniformly within ZnTe is found to segregate dramatically after RTP activation, either collecting near the ZnTe/Au interface or forming CUxTe clusters in CdTe at defects or grain boundaries near the interface with ZnTe. Chlorine, present throughout CdTe and concentrated at grain boundaries, does not penetrate significantly into the back contact region during RTP activation

A feasibility study into the production of a mussel matrix reference material for the cyanobacterial toxins microcystins and nodularins.

Microcystins and nodularins, produced naturally by certain species of cyanobacteria, have been found to accumulate in aquatic foodstuffs such as fish and shellfish, resulting in a risk to the health of the seafood consumer. Monitoring of toxins in such organisms for risk management purposes requires the availability of certified matrix reference materials to aid method development, validation and routine quality assurance. This study consequently targeted the preparation of a mussel tissue reference material incurred with a range of microcystin analogues and nodularins. Nine targeted analogues were incorporated into the material as confirmed through liquid chromatography with tandem mass spectrometry (LC-MS/MS), with an additional 15 analogues detected using LC coupled to non-targeted high resolution mass spectrometry (LC-HRMS). Toxins in the reference material and additional source tissues were quantified using LC-MS/MS, two different enzyme-linked immunosorbent assay (ELISA) methods and with an oxidative-cleavage method quantifying 3-methoxy-2-methyl-4-phenylbutyric acid (MMPB). Correlations between the concentrations quantified using the different methods were variable, likely relating to differences in assay cross-reactivities and differences in the abilities of each method to detect bound toxins. A consensus concentration of total soluble toxins determined from the four independent test methods was 2425 ± 575 µg/kg wet weight. A mean 43 ± 9% of bound toxins were present in addition to the freely extractable soluble form (57 ± 9%). The reference material produced was homogenous and stable when stored in the freezer for six months without any post-production stabilization applied. Consequently, a cyanotoxin shellfish reference material has been produced which demonstrates the feasibility of developing certified seafood matrix reference materials for a large range of cyanotoxins and could provide a valuable future resource for cyanotoxin risk monitoring, management and mitigation