Organic flow assurance: Asphaltene dispersant/inhibitor formulation development through experimental design

Master's thesis in Environmental TechnologyThe exploitation of hydrocarbon has forced the petroleum production to move closer to extreme climate areas and deep waters such as the Barents Sea. These challenges require effective and safe production, transport and processing of the petroleum sources. Chemical and physical changes in the reservoir may cause different types of unpredicted problems such as organic deposits which are mainly asphaltene and wax precipitation. Wax precipitation is very common in subsea pipelines. Asphaltenes are more affected by for example pressure drops and high shear, which may cause formation damage as well as plugup the well-bores and tubing. In the petroleum industry, flow assurance has become a key concern where the cold sea bottom temperatures and extreme water depths give rise to enormous technical challenges which includes the management of solids such as asphaltenes and wax. Flow assurance is defined as “safe, uninterrupted and simultaneous transport of gas, oil and water from reservoirs to processing facilities”. The term refers to the need to guarantee flow of oil and gas from the reservoirs to the processing facilities. In this thesis the focus will be on chemical control of asphaltene and the formulation of an optimal asphaltene dispersant mixture. An experimental method needed to be established for the screening tests of the dispersant mixtures. When performing a screening test, the experimental method is desired to be simple and quick. This will save time and money as the screening test will only give an idea of how the system works and interacts. Different methods were tested such as measurement of the asphaltene deposit level, spot test, UV-Vis spectroscopy and turbidity measurements. Turbidity measurement was decided to be used in the formulation of an optimal asphaltene dispersant mixture. Design of experiments (DoE) and mixture design are well known methods which are often used when mixing together multiple components. DoE techniques provide an idea of how the mixtures work together and can then optimize the formulation at a minimum effort and cost. The computer software, Design Expert was used for the experimental design in this thesis. The program was used to set up an experimental plan which showed the mixture components and the mixture proportions to be tested. When the results were ready, they were inserted in Design Expert and a model was suggested. The analysis of the model was also done by Design Expert which made it possible to easily detect certain trends in the model such as identifying results that deviated from the model in form of failed experiments. Three different crude oils were tested, Crudo-Metapetroleum a viscous and heavy crude oil with an asphaltene content of 12,1535g/100ml, Hier D02A crude oil which is a more common crude oil with an asphaltene content of 2,2380g/100ml and Jordbær crude oil with an asphaltene content of 0,2210g/100ml. Three commercial asphaltene dispersant were tested in order to find an optimal mixture formulation. The dispersants used for these tests, dodecyl benzene sulfonic acid (DDBSA), Hybase M-401 and Flowsolve 113, did not show any usable synergistic effects. The results showed that the best dispersant was Flowsolve 113

Pauli Paramagnetic Effects on Vortices in Superconducting TmNi2B2C

The magnetic field distribution around the vortices in TmNi2B2C in the paramagnetic phase was studied experimentally as well as theoretically. The vortex form factor, measured by small-angle neutron scattering, is found to be field independent up to 0.6 Hc2 followed by a sharp decrease at higher fields. The data are fitted well by solutions to the Eilenberger equations when paramagnetic effects due to the exchange interaction with the localized 4f Tm moments are included. The induced paramagnetic moments around the vortex cores act to maintain the field contrast probed by the form factor.Comment: 4 pages, 4 figure

T cell specific adaptor protein (TSAd) promotes interaction of Nck with Lck and SLP-76 in T cells

Background: The Lck and Src binding adaptor protein TSAd (T cell specific adaptor) regulates actin polymerization in T cells and endothelial cells. The molecular details as to how TSAd regulates this process remain to be elucidated. Results: To identify novel interaction partners for TSAd, we used a scoring matrix-assisted ligand algorithm (SMALI), and found that the Src homology 2 (SH2) domain of the actin regulator Non-catalytic region of tyrosine kinase adaptor protein (Nck) potentially binds to TSAd phosphorylated on Tyr280 (pTyr280) and pTyr305. These predictions were confirmed by peptide array analysis, showing direct binding of recombinant Nck SH2 to both pTyr280 and pTyr305 on TSAd. In addition, the SH3 domains of Nck interacted with the proline rich region (PRR) of TSAd. Pull-down and immunoprecipitation experiments further confirmed the Nck-TSAd interactions through Nck SH2 and SH3 domains. In line with this Nck and TSAd co-localized in Jurkat cells as assessed by confocal microscopy and imaging flow cytometry. Co-immunoprecipitation experiments in Jurkat TAg cells lacking TSAd revealed that TSAd promotes interaction of Nck with Lck and SLP-76, but not Vav1. TSAd expressing Jurkat cells contained more polymerized actin, an effect dependent on TSAd exon 7, which includes interactions sites for both Nck and Lck. Conclusions: TSAd binds to and co-localizes with Nck. Expression of TSAd increases both Nck-Lck and Nck-SLP-76 interaction in T cells. Recruitment of Lck and SLP-76 to Nck by TSAd could be one mechanism by which TSAd promotes actin polymerization in activated T cells. © 2015 Hem et al

Prenatal exposure to vitamin D from fortified margarine and risk of fractures in late childhood:period and cohort results from 222 000 subjects in the D-tect observational study

Prenatal low vitamin D may have consequences for bone health. By means of a nationwide mandatory vitamin D fortification programme, we examined the risk of fractures among 10–18-year-old children from proximate birth cohorts born around the date of the termination of the programme. For all subjects born in Denmark during 1983–1988, civil registration numbers were linked to the Danish National Patient Registry for incident and recurrent fractures occurring at ages 10–18 years. Multiplicative Poisson models were used to examine the association between birth cohort and fracture rates. The variation in fracture rates across birth cohorts was analysed by fitting an age-cohort model to the data. We addressed the potential modification of the effect of vitamin D availability by season of birth. The risk of fractures was increased among both girls and boys who were born before the vitamin D fortification terminated in 1985 (rate ratio (RR) exposed v. non-exposed girls: 1·15 (95 % CI 1·11, 1·20); RR exposed v. non-exposed boys: 1·11 (95 % CI 1·07, 1·14). However, these associations no longer persisted after including the period effects. There was no interaction between season of birth and vitamin D availability in relation to fracture risk. The study did not provide evidence that prenatal exposure to extra vitamin D from a mandatory fortification programme of 1·25 µg vitamin D/100 g margarine was sufficient to influence the risk of fractures in late childhood, regardless of season of birth. Replication studies are needed

Low Levels of Hemoglobin at Admission Are Associated With Increased 30-Day Mortality in Patients With Hip Fracture

INTRODUCTION: Previous smaller studies suggest that anemia is a risk factor for mortality in patients with hip fracture. The purpose of this investigation was to assess the correlation between hemoglobin at admission with 30-day mortality following a hip fracture in a large-scale study. PATIENTS AND METHODS: From January 1996 to December 2012, all patients with hip fracture (>60 years of age) admitted to Bispebjerg Hospital, Copenhagen, were identified from a local hip fracture database. We excluded conservatively treated patients and patients who died preoperatively. RESULTS: Seven thousand four hundred twenty-one consecutive patients with hip fracture were identified. Of those 7319 had a hemoglobin measurement on admission and were thus eligible for further analysis. Mean hemoglobin for patients alive at 30 days was 7.6 (standard deviation [SD]: 1.0) and for deceased patients 7.4 (SD: 1.1), P < .0001. Mean age was 82.6 years (SD: 8.5), and 76.5% of the population were female (N(females) = 5600). The 30-day mortality decreases for every increase in hemoglobin of 1.0 mmol/L in a univariate analysis (P < .0001). The hazard ratio (HR) with 95% confidence interval (CI) for 30-day mortality in patients with anemia (<7.3 mmol/L for females and <8.3 mmol/L for males; N(anemic) = 3235) was 1.66 (CI: 1.43-1.91, P < .0001). Adjusting for age, type of fracture, gender, and comorbidities (Charlson score) slightly attenuated the risk estimate (HR: 1.21, CI: 1.03-1.41, P = .02). CONCLUSION: This study demonstrates increased 30-day mortality in patients with low hemoglobin at admission, even after adjusting for comorbidities

Temperature Dependence of the Flux Line Lattice Transition into Square Symmetry in Superconducting LuNi2_2B2_2C

We have investigated the temperature dependence of the H || c flux line lattice structural phase transition from square to hexagonal symmetry, in the tetragonal superconductor LuNi_2B_2C (T_c = 16.6 K). At temperatures below 10 K the transition onset field, H_2(T), is only weakly temperature dependent. Above 10 K, H_2(T) rises sharply, bending away from the upper critical field. This contradicts theoretical predictions of H_2(T) merging with the upper critical field, and suggests that just below the H_c2(T)-curve the flux line lattice might be hexagonal.Comment: 4 pages, 3 figure

Fermi surface and order parameter driven vortex lattice structure transitions in twin-free YBa2Cu3O7

We report on small-angle neutron scattering studies of the intrinsic vortex lattice (VL) structure in detwinned YBa2Cu3O7 at 2 K, and in fields up to 10.8 T. Because of the suppressed pinning to twin-domain boundaries, a new distorted hexagonal VL structure phase is stabilized at intermediate fields. It is separated from a low-field hexagonal phase of different orientation and distortion by a first-order transition at 2.0(2) T that is probably driven by Fermi surface effects. We argue that another first-order transition at 6.7(2) T, into a rhombic structure with a distortion of opposite sign, marks a crossover from a regime where Fermi surface anisotropy is dominant, to one where the VL structure and distortion is controlled by the order-parameter anisotropy.Comment: 4 pages, 3 figures (2 color), minor change

Shifts in Global Security Policies: Why They Matter for the South

The global security order has been evolving since 1989, led initially by the USA to expand its post?1945 order in Europe to the rest of the world but propelled as well by competition and debates within that post?Second World War alliance, as collective victors in the Cold War, about how to define a new international order. This article identifies three US policies that began this restructuring; their parallel redefinitions of security, and the tensions provoked by this agenda and its consequences, both within the ‘North’, replacing the ‘West’, between North and ‘South’, replacing the‘East’and the resulting multiple opportunities for alternative political coalitions, North against South, between North and South, and within the South, that have yet to play themselves out fully. The resulting fluidity has not yet stabilised into a new international security order

The Amundsen Sea Polynya International Research Expedition (ASPIRE)

In search of an explanation for some of the greenest waters ever seen in coastal Antarctica and their possible link to some of the fastest melting glaciers and declining summer sea ice, the Amundsen Sea Polynya International Research Expedition (ASPIRE) challenged the capabilities of the US Antarctic Program and RVIB Nathaniel B. Palmer during Austral summer 2010–2011. We were well rewarded by both an extraordinary research platform and a truly remarkable oceanic setting. Here we provide further insights into the key questions that motivated our sampling approach during ASPIRE and present some preliminary findings, while highlighting the value of the Palmer for accomplishing complex, multifaceted oceanographic research in such a challenging environment

A Multidomain Adhesion Protein Family Expressed in Plasmodium falciparum Is Essential for Transmission to the Mosquito

The recent sequencing of several apicomplexan genomes has provided the opportunity to characterize novel antigens essential for the parasite life cycle that might lead to the development of new diagnostic and therapeutic markers. Here we have screened the Plasmodium falciparum genome sequence for genes encoding extracellular multidomain putative adhesive proteins. Three of these identified genes, named PfCCp1, PfCCp2, and PfCCp3, have multiple adhesive modules including a common Limulus coagulation factor C domain also found in two additional Plasmodium genes. Orthologues were identified in the Cryptosporidium parvum genome sequence, indicating an evolutionary conserved function. Transcript and protein expression analysis shows sexual stage–specific expression of PfCCp1, PfCCp2, and PfCCp3, and cellular localization studies revealed plasma membrane–associated expression in mature gametocytes. During gametogenesis, PfCCps are released and localize surrounding complexes of newly emerged microgametes and macrogametes. PfCCp expression markedly decreased after formation of zygotes. To begin to address PfCCp function, the PfCCp2 and PfCCp3 gene loci were disrupted by homologous recombination, resulting in parasites capable of forming oocyst sporozoites but blocked in the salivary gland transition. Our results describe members of a conserved apicomplexan protein family expressed in sexual stage Plasmodium parasites that may represent candidates for subunits of a transmission-blocking vaccine