Lithium extraction from oilfield brine

Lithium production through atmospheric evaporation of saline brine is generally the most economically efficient method of extraction. As global demand for lithium increases, production technology has evolved to reduce processing time of lithium from brine. The resulting technology invites the opportunity to consider lithium production from lower concentration petroleum brines, a long-overlooked lithium-rich resource. Capitalizing on advanced filtration technology and petroleum well infrastructure, the petroleum-producing geologic formations in the U.S. were evaluated for their lithium production potential. The U.S. Geological Survey National Produced Waters Geochemical Database was utilized to identify lithium-rich brine from wells across the U.S. The volume and concentration potential of the most promising lithium-enriched geologic formation were calculated. Historical and current well production data were compiled and used to estimate the expected lithium production for the geologic formation. This data was then applied to a financial model to determine the method of brine production under which extracting lithium from oilfield brine would be profitable. Advanced technology offers the advantage of recovering Li from concentrations as low as 70 mg/L. Of the produced water samples, only 344 samples had Li concentrations greater than or equal to 70 mg/L. The majority of the high Li concentration samples were identified in the Smackover Formation. The Smackover was selected to analyze for lithium extraction and production. Lithium-enriched brine can be gathered from the Smackover by collecting produced water from active wells in the formation or by drilling a purpose-designed well to access brine. Despite the ability to recover low-concentration lithium in brines, Results from the financial analysis indicate that the profitability of lithium extraction from Smackover oilfield brine is dependent on the lithium concentration of brine that is processed by the facility. Profit can be further enhanced by using economies of scale to increase the brine processing capacity of the facility. In this analysis, drilling a purpose-designed well resulted in the only profitable endeavor. When utilizing existing infrastructure to collect brine, the profitability is highly dependent on the number of active wells that produce from the Smackover Formation. This analysis indicates that a standalone lithium extraction company is best positioned to capitalize on lithium extraction from oilfield brine.Energy and Earth ResourcesBusiness Administratio

Six family factors and their relationships to patients' performance in group therapy

Thesis (M.S.)--Boston Universit

Synchronous gastric and duodenal metastases from head and neck squamous cell carcinoma: a unique presentation of upper gastrointestinal bleeding.

Metastatic disease to the stomach or duodenum is an infrequent diagnosis, and head and neck squamous cell carcinoma (HNSCC) is one of the least common primary malignancies that lead to gastric or duodenal metastases. We report the case of a 65-year-old man with human immunodeficiency virus infection and previously diagnosed HNSCC who presented with melena. The patient had a percutaneous endoscopic gastrostomy tube placed 3 months prior to his presentation. Laboratory testing was significant for normocytic anemia and a digital rectal examination was positive for melena. Esophagogastroduodenoscopy revealed numerous cratered nodules with contact bleeding in the stomach as well as the duodenum that appeared malignant. Biopsies of the gastric and duodenal nodules were positive for p40 and CK 5/6, consistent with metastatic squamous cell carcinoma

OSMOREGULATED PERIPLASMIC GLUCAN METABOLISM IS REQUIRED FOR STRESS SURVIVAL AND MORPHOLOGY IN CAULOBACTER CRESCENTUS

Bacterial growth and division requires precise regulation of enzymatic activity in order to remodel the cell envelope without compromising its integrity. Thus, it is essential to identify and characterize enzymes that maintain cell envelope homeostasis as they can be potential antibiotic targets. In this dissertation, we have identified the enzyme, EstG, that protects cells from a variety of lethal assaults in the ⍺-proteobacterium Caulobacter crescentus. Despite homology to cell wall-acting enzymes, EstG does not have detectable activity on the cell wall. To explore the novel function of EstG, we identified and characterized genetic connections with OpgH and BglX, enzymes involved in the synthesis and hydrolysis of osmoregulated periplasmic glucans (OPGs). The crystal structure of EstG revealed similarities to esterases and transesterases and we consequently demonstrated in vitro esterase activity of EstG. We were ultimately able to identify the substrate of EstG through an unbiased mass spectrometry screen. The substrate, a cyclic hexamer of glucose, is the first OPG identified in Caulobacter, that we predict EstG modifies to contribute to cell envelope integrity during stress. Ultimately, this data places EstG in the undiscovered OPG pathway in Caulobacter and establishes a new class of enzymes required for resistance to stress through OPG metabolism. We further elucidated a connection between the OPG pathway and morphological homeostasis in Caulobacter through the enzyme, OpgH. Beyond a genetic interaction with EstG, OpgH is an essential factor required for maintaining cellular morphology during growth and division. Cell lacking OpgH exhibit asymmetric bulging and lysis, as well as mislocalization of cell wall synthesis and the primary morphogenetic complexes. Lastly, we determined that the glycosyltransferase activity of OpgH, presumably synthesis of OPGs, that is responsible for preventing the observed morphological defects. Through this thesis work, we have characterized two enzymes in the OPG pathway that are required for stress response (EstG) and morphology (OpgH). Our findings have shed light on an unexplored pathway harboring numerous enzymes that can be investigated as potential targets for antibiotics

Translating alloy using Boolean circuits

Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2004.Includes bibliographical references (p. 71-72).Alloy is a automatically analyzable modelling language based on first-order logic. An Alloy model can be translated into a Boolean formula whose satisfying assignments correspond to instances in the model. Currently, the translation procedure mechanically converts each piece of the Alloy model individually into its most straightforward Boolean representation. This thesis proposes a more efficient approach to translating Alloy models. The key is to take advantage of the fact that an Alloy model contains patterns that are used repeatedly. This makes it natural to give a model a more structured Boolean representation, namely a Boolean circuit. Reusable pieces in the model correspond to circuit components. By identifying the most frequently used components and optimizing their corresponding Boolean formulas, the size of the overall formula for the model would be reduced without significant additional work. A smaller formula would potentially decrease the time required to determine satisfiability, resulting in faster analysis overall.by Samuel Isaac Daitch.M.Eng

Um campo em disputa: Comunistas e Trotskistas na reconfiguração das esquerdas argentinas (1943-1960)

Resumo: o campo das esquerdas na Argentina das décadas de 1940 e 1950 sofreu importantes transformações. Comunistas, nacionalistas, trotskistas, revolucionários heterodoxos e demais representantes da esquerda argentina viram-se obrigados a reverem suas posições diante de novíssimos processos históricos e políticos que colocavam em xeque antigos conceitos e leituras de conjuntura. O peronismo a nível nacional e o populismo a nível continental, bem como o novo contexto do capitalismo obrigaram intelectuais de variados campos políticos a repensarem seu projeto de nação bem como sua própria identidade política. Por isso, o presente texto procura contextualizar as disputas teóricas entre variados partidos que se proclamavam de esquerda apontando releituras realizadas diante dos novos processos históricos em gestação. Palavras-chave: Argentina. Peronismo. Esquerdas.&nbsp

Distinct phase-amplitude couplings distinguish cognitive processes in human attention

Abstract Spatial attention is the cognitive function that coordinates the selection of visual stimuli with appropriate behavioral responses. Recent studies have reported that phase-amplitude coupling (PAC) of low and high frequencies covaries with spatial attention, but differ on the direction of covariation and the frequency ranges involved. We hypothesized that distinct phase-amplitude frequency pairs have differentiable contributions during tasks that manipulate spatial attention. We investigated this hypothesis with electrocorticography (ECoG) recordings from participants who engaged in a cued spatial attention task. To understand the contribution of PAC to spatial attention we classified cortical sites by their relationship to spatial variables or behavioral performance. Local neural activity in spatial sites was sensitive to spatial variables in the task, while local neural activity in behavioral sites correlated with reaction time. We found two PAC frequency clusters that covaried with different aspects of the task. During a period of cued attention, delta-phase/high-gamma (DH) PAC was sensitive to cue direction in spatial sites. In contrast, theta-alpha-phase/beta-low-gamma-amplitude (TABL) PAC robustly correlated with future reaction times in behavioral sites. Finally, we investigated the origins of TABL PAC and found it corresponded to behaviorally relevant, sharp waveforms, which were also coupled to a low frequency rhythm. We conclude that TABL and DH PAC correspond to distinct mechanisms during spatial attention tasks and that sharp waveforms are elements of a coupled dynamical process