129 research outputs found
The effect of ionic strength on oil adhesion in sandstone - the search for the low salinity mechanism
Core flood and field tests have demonstrated that decreasing injection water salinity increases oil recovery from sandstone reservoirs. However, the microscopic mechanism behind the effect is still under debate. One hypothesis is that as salinity decreases, expansion of the electrical double layer decreases attraction between organic molecules and pore surfaces. We have developed a method that uses atomic force microscopy (AFM) in chemical force mapping (CFM) mode to explore the relationship between wettability and salinity. We functionalised AFM tips with alkanes and used them to represent tiny nonpolar oil droplets. In repeated measurements, we brought our āoilā close to the surface of sand grains taken from core plugs and we measured the adhesion between the tip and sample. Adhesion was constant in high salinity solutions but below a threshold of 5,000 to 8,000 ppm, adhesion decreased as salinity decreased, rendering the surface less oil wet. The effect was consistent, reproducible and reversible. The threshold for the onset of low salinity response fits remarkably well with observations from core plug experiments and field tests. The results demonstrate that the electric double layer force always contributes at least in part to the low salinity effect, decreasing oil wettability when salinity is low
Biobanking, consent, and commercialization in international genetics research: the Type 1 Diabetes Genetics Consortium
Background and Purpose This article describes several ethical, legal, and social issues typical of
international genetics biobanking, as encountered in the Type 1 Diabetes Genetics Consortium
(T1DGC)
Growth Mechanism of Self-Catalyzed Group IIIāV Nanowires
Group III-V nanowires offer the exciting possibility of epitaxial growth on a wide variety of substrates, most importantly silicon. To ensure compatibility with Si technology, catalyst-free growth schemes are of particular relevance, to avoid impurities from the catalysts. While this type of growth is well-documented and some aspects are described, no detailed understanding of the nucleation and the growth mechanism has been developed. By combining a series of growth experiments using metal-organic vapor phase epitaxy, as well as detailed in situ surface imaging and spectroscopy, we gain deeper insight into nucleation and growth of self-seeded III-V nanowires. By this mechanism most work available in literature concerning this field can be described
Association of education with dietary intake among young adults in the bi-ethnic Coronary Artery Risk Development in Young Adults (CARDIA) cohort
OBJECTIVE: To examine associations of changes in dietary intake with education in young black and white men and women.
DESIGN: The Coronary Artery Risk Development in Young Adults (CARDIA) study, a multi-centre population-based prospective study. Dietary intake data at baseline and year 7 were obtained from an extensive nutritionist-administered diet history questionnaire with 700 items developed for CARDIA.
SETTING: Participants were recruited in 1985-1986 from four sites: Birmingham, Alabama; Chicago, Illinois; Minneapolis, Minnesota; and Oakland, California.
SUBJECTS: Participants were from a general community sample of 703 black men (BM), 1006 black women (BW), 963 white men (WM) and 1054 white women (WW) who were aged 18-30 years at baseline. Analyses here include data for baseline (1985-1986) and year 7 (1992-1993).
RESULTS: Most changes in dietary intake were observed among those with high education (\u3eor=12 years) at both examinations. There was a significant decrease in intake of energy from saturated fat and cholesterol and a significant increase in energy from starch for each race-gender group (P\u3c0.001). Regardless of education, taste was considered an important influence on food choice.
CONCLUSION: The inverse relationship of education with changes in saturated fat and cholesterol intakes suggests that national public health campaigns may have a greater impact among those with more education
Measurement of islet cell antibodies in the Type 1 Diabetes Genetics Consortium: efforts to harmonize procedures among the laboratories
Background and Purpose Three network laboratories measured antibodies to islet autoantigens.
Antibodies to glutamic acid decarboxylase (GAD65 [GADA]) and the intracellular
portion of protein tyrosine phosphatase (IA-2ic [IA-2A]) were
measured by similar, but not identical, methods in samples from participants in
the Type 1 Diabetes Genetics Consortium (T1DGC)
Tests for Genetic Interactions in Type 1 Diabetes: Linkage and Stratification Analyses of 4,422 Affected Sib-Pairs
OBJECTIVE - Interactions between genetic and environmental factors lead to immune dysregulation causing type 1 diabetes and other autoimmune disorders. Recently, many common genetic variants have been associated with type 1 diabetes risk, but each has modest individual effects. Familial clustering of type 1 diabetes has not been explained fully and could arise from many factors, including undetected genetic variation and gene interactions. RESEARCH DESIGN AND METHODS - To address this issue, the Type 1 Diabetes Genetics Consortium recruited 3,892 families, including 4,422 affected sib-pairs. After genotyping 6,090 markers, linkage analyses of these families were performed, using a novel method and taking into account factors such as genotype at known susceptibility loci. RESULTS - Evidence for linkage was robust at the HLA and INS loci, with logarithm of odds (LOD) scores of 398.6 and 5.5, respectively. There was suggestive support for five other loci. Stratification by other risk factors (including HLA and age at diagnosis) identified one convincing region on chromosome 6q14 showing linkage in male subjects (corrected LOD = 4.49; replication P = 0.0002), a locus on chromosome 19q in HLA identical siblings (replication P = 0.006), and four other suggestive loci. CONCLUSIONS - This is the largest linkage study reported for any disease. Our data indicate there are no major type 1 diabetes subtypes definable by linkage analyses; susceptibility is caused by actions of HLA and an apparently random selection from a large number of modest-effect loci; and apart from HLA and INS, there is no important susceptibility factor discoverable by linkage methods
Quality control of phenotypic forms data in the Type 1 Diabetes Genetics Consortium
Background When collecting phenotypic data in clinics across the globe, the Type 1 Diabetes
Genetics Consortium (T1DGC) used several techniques that ensured consistency, completeness, and
accuracy of the data
HLA genotyping in the international Type 1 Diabetes Genetics Consortium
Background Although human leukocyte antigen (HLA) DQ and
DR loci appear to confer the strongest genetic risk for
type 1 diabetes, more detailed information is required for other loci within the
HLA region to understand causality and stratify additional risk factors. The
Type 1 Diabetes Genetics Consortium (T1DGC) study design included
high-resolution genotyping of HLA-A, B,
C, DRB1, DQ, and
DP loci in all affected sibling pair and trio families, and
cases and controls, recruited from four networks worldwide, for analysis with
clinical phenotypes and immunological markers
Designing and implementing sample and data collection for an international genetics study: the Type 1 Diabetes Genetics Consortium (T1DGC)
Background and PurposeāThe Type 1 Diabetes Genetics Consortium (T1DGC) is an
international project whose primary aims are to: (a) discover genes that modify
type 1 diabetes risk; and (b) expand upon the existing genetic resources for
type 1 diabetes research. The initial goal was to collect 2500 affected sibling
pair (ASP) families worldwide
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