| 1. |
- Cao, Rihong, et al.
(författare)
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Failure mechanism of non-persistent jointed rock-like specimens under uniaxial loading : Laboratory testing
- 2020
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Ingår i: International Journal of Rock Mechanics And Mining Sciences. - : Elsevier. - 1365-1609 .- 1873-4545. ; 132
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Tidskriftsartikel (refereegranskat)abstract
- It is generally known that discontinuities have a remarkable influence on the mechanical behaviour of rock masses. To further understand the fracture mechanisms of jointed rock masses, substantial effort has been focused on the strength anisotropy and failure characteristics of rocks/rock-like specimens containing persistent joints with different geometric parameters. However, only a few laboratory tests have considered the failure mechanism of a rock mass with 3D joints, especially for non-persistent joints with different persistence levels. In the present work, experiments on cubic rock-like specimens containing non-persistent joints (in areal extent) subjected to uniaxial compression were conducted to further investigate the influence of the joint inclination (θ) and persistence (N) on the rock mechanical properties and failure characteristics. The strength of a 3D non-persistent jointed specimen is characterized by three stages as the joint inclination angle (θ) increases from 0° to 90°. The strength of jointed specimens decreases with increasing N for all θ values, with the highest strength obtained for N = 0.42 and the lowest strength recorded for N = 0.92. Based on CT scan results, four typical fracture modes were identified: splitting, splitting + sliding, sliding, and intact failure. Overall, as the joint inclination increases, the failure mode of the specimen transforms from splitting to sliding and then to the intact failure mode. However, with decreasing joint persistence, the failure modes of some specimens will change from sliding to mixed failure (splitting + sliding).
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| 2. |
- Lin, Qibin, et al.
(författare)
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Mechanical behavior around double circular openings in a jointed rock mass under uniaxial compression
- 2020
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Ingår i: Archives of Civil and Mechanical Engineering. - : Springer. - 1644-9665. ; 20:1
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Tidskriftsartikel (refereegranskat)abstract
- To better understand the mechanical behavior in a jointed rock mass, a series of uniaxial compression tests were conducted on non-persistently jointed rock specimens with double circular holes. Acoustic emission (AE) and digital image correlation (DIC) techniques were applied to capture micro-crack events and real-time strain field evolution in the specimens. The results indicate that the existence of non-persistent joints has a significant influence on the strength characteristics of the specimens. Specifically, peak strength decreases at first and reaches a minimum at 30° then increases with increase in the joint dip angle. DIC technology has successfully monitored the development of surface strain fields. The fracture evolution process is comprehensively understood. Every sudden change in a strain field is usually accompanied by apparent AE events and stress–strain curves take the form of oscillations. The crack coalescence modes among joints can be summarized as six types and the crack coalescence patterns around holes and joints can be divided into three categories. These results are helpful to understanding further the mechanical properties and fracture mechanism of openings in non-persistently jointed rock masses.
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| 3. |
- Qi, Qibin, et al.
(författare)
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FTO genetic variants, dietary intake and body mass index : insights from 177 330 individuals
- 2014
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Ingår i: Human Molecular Genetics. - : Oxford University Press (OUP). - 0964-6906 .- 1460-2083. ; 23:25, s. 6961-6972
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Tidskriftsartikel (refereegranskat)abstract
- FTO is the strongest known genetic susceptibility locus for obesity. Experimental studies in animals suggest the potential roles of FTO in regulating food intake. The interactive relation among FTO variants, dietary intake and body mass index (BMI) is complex and results from previous often small-scale studies in humans are highly inconsistent. We performed large-scale analyses based on data from 177 330 adults (154 439 Whites, 5776 African Americans and 17 115 Asians) from 40 studies to examine: (i) the association between the FTO-rs9939609 variant (or a proxy single-nucleotide polymorphism) and total energy and macronutrient intake and (ii) the interaction between the FTO variant and dietary intake on BMI. The minor allele (A-allele) of the FTO-rs9939609 variant was associated with higher BMI in Whites (effect per allele = 0.34 [0.31, 0.37] kg/m(2), P = 1.9 × 10(-105)), and all participants (0.30 [0.30, 0.35] kg/m(2), P = 3.6 × 10(-107)). The BMI-increasing allele of the FTO variant showed a significant association with higher dietary protein intake (effect per allele = 0.08 [0.06, 0.10] %, P = 2.4 × 10(-16)), and relative weak associations with lower total energy intake (-6.4 [-10.1, -2.6] kcal/day, P = 0.001) and lower dietary carbohydrate intake (-0.07 [-0.11, -0.02] %, P = 0.004). The associations with protein (P = 7.5 × 10(-9)) and total energy (P = 0.002) were attenuated but remained significant after adjustment for BMI. We did not find significant interactions between the FTO variant and dietary intake of total energy, protein, carbohydrate or fat on BMI. Our findings suggest a positive association between the BMI-increasing allele of FTO variant and higher dietary protein intake and offer insight into potential link between FTO, dietary protein intake and adiposity.
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| 4. |
- Flannick, Jason, et al.
(författare)
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Data Descriptor : Sequence data and association statistics from 12,940 type 2 diabetes cases and controls
- 2017
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Ingår i: Scientific Data. - : Springer Science and Business Media LLC. - 2052-4463. ; 4
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Tidskriftsartikel (refereegranskat)abstract
- To investigate the genetic basis of type 2 diabetes (T2D) to high resolution, the GoT2D and T2D-GENES consortia catalogued variation from whole-genome sequencing of 2,657 European individuals and exome sequencing of 12,940 individuals of multiple ancestries. Over 27M SNPs, indels, and structural variants were identified, including 99% of low-frequency (minor allele frequency [MAF] 0.1-5%) non-coding variants in the whole-genome sequenced individuals and 99.7% of low-frequency coding variants in the whole-exome sequenced individuals. Each variant was tested for association with T2D in the sequenced individuals, and, to increase power, most were tested in larger numbers of individuals (> 80% of low-frequency coding variants in similar to ~82 K Europeans via the exome chip, and similar to ~90% of low-frequency non-coding variants in similar to ~44 K Europeans via genotype imputation). The variants, genotypes, and association statistics from these analyses provide the largest reference to date of human genetic information relevant to T2D, for use in activities such as T2D-focused genotype imputation, functional characterization of variants or genes, and other novel analyses to detect associations between sequence variation and T2D.
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| 5. |
- Fuchsberger, Christian, et al.
(författare)
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The genetic architecture of type 2 diabetes
- 2016
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 536:7614, s. 41-47
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Tidskriftsartikel (refereegranskat)abstract
- The genetic architecture of common traits, including the number, frequency, and effect sizes of inherited variants that contribute to individual risk, has been long debated. Genome-wide association studies have identified scores of common variants associated with type 2 diabetes, but in aggregate, these explain only a fraction of the heritability of this disease. Here, to test the hypothesis that lower-frequency variants explain much of the remainder, the GoT2D and T2D-GENES consortia performed whole-genome sequencing in 2,657 European individuals with and without diabetes, and exome sequencing in 12,940 individuals from five ancestry groups. To increase statistical power, we expanded the sample size via genotyping and imputation in a further 111,548 subjects. Variants associated with type 2 diabetes after sequencing were overwhelmingly common and most fell within regions previously identified by genome-wide association studies. Comprehensive enumeration of sequence variation is necessary to identify functional alleles that provide important clues to disease pathophysiology, but large-scale sequencing does not support the idea that lower-frequency variants have a major role in predisposition to type 2 diabetes.
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| 6. |
- Lin, Qibin, et al.
(författare)
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Crack coalescence in rock-like specimens with two dissimilar layers and pre-existing double parallel joints under uniaxial compression
- 2021
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Ingår i: International Journal of Rock Mechanics And Mining Sciences. - : Elsevier. - 1365-1609 .- 1873-4545. ; 139
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Tidskriftsartikel (refereegranskat)abstract
- Layered rock masses with joints are widely found in nature. Their mechanical behavior plays a key role in rock engineering applications. However, previous studies have concentrated on the single lithologic layer, and few studies have reported the crack coalescence mechanism in layered rock masses with joints. In this study, uniaxial compression tests were performed on jointed rock-like specimens with two dissimilar layers. The acoustic emission (AE) and the digital image correlation (DIC) techniques are employed to investigate the crack coalescence process of specimens with two dissimilar layers. The influence of the joint angle and rock bridge angle on the mechanical behavior and failure processes in layered rock masses is investigated. The results show that the peak strength is associated with the joint angle and the rock bridge angle. Seven types of crack coalescence have been identified in the specimens, which are not only related to the joint angle and the rock bridge angle but also influenced by the rock layers. Cracks easily coalesce when the joint angle and the rock bridge angle are small. However, when the joint angle and the rock bridge angle are larger, it is difficult for cracks to initiate and propagate in the layer with higher strength. The failure mechanism of the specimens is primarily caused by crack propagation in the layer with lower strength.
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| 7. |
- Lin, Qibin, et al.
(författare)
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Strength and failure characteristics of jointed rock mass with double circular holes under uniaxial compression : Insights from discrete element method modelling
- 2020
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Ingår i: Theoretical and applied fracture mechanics (Print). - : Elsevier. - 0167-8442 .- 1872-7638. ; 109
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Tidskriftsartikel (refereegranskat)abstract
- Underground projects are typically performed in nonpersistent jointed rock masses. Excavation of tunnels or chambers causes crack initiation, propagation and coalescence, resulting in the instability and destruction of surrounding rocks. The failure behaviour of rocks is complicated owing to the interaction between holes and joints. Therefore, understanding the failure characteristics of holes in jointed rock masses is essential. In this paper, the mechanical characteristics of a jointed rock mass with double circular holes under uniaxial loading was investigated using the discrete element method. The effects of different joint parameters on the strength and failure behaviour of the jointed rock mass with double circular holes were studied. The results show that the existence of joints degrades the mechanical behaviour of the rock mass. Specifically, the peak strength and elastic modulus of the specimens show a “U” shape change with the joint dip angle and reach the minimum value when the angle is 30°. With an increase in joint spacing, the peak strength and elastic modulus increase gradually. An investigation of the crack coalescence process and displacement field of the specimens reveal the crack propagation mechanism based on the interaction between holes and joints under uniaxial loading. Five types of crack coalescence among the holes and adjacent joints were summarized. Four typical failure modes were observed: tensile failure across joints, block rotation failure around holes, shear failure through joint planes and tensile–shear mixed failure through holes.
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| 8. |
- Reynolds, Kaylia, et al.
(författare)
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Circulating Metabolites Associated with Albuminuria in a Hispanic/Latino Population
- 2023
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Ingår i: Clinical journal of the American Society of Nephrology : CJASN. - 1555-905X. ; 18:2, s. 204-212
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Tidskriftsartikel (refereegranskat)abstract
- Background. Albuminuria is associated with metabolic abnormalities, but these relationships are not well understood. We studied the association of metabolites with albuminuria in Hispanics/Latinos, a population with high risk for metabolic disease. Methods. We used data from 3,736 participants from the Hispanic Community Health Study/Study of Latinos, of which 16% had diabetes and 9% had an increased urine albumin to creatinine ratio (UACR). Metabolites were quantified in fasting serum through non-targeted mass spectrometry (MS) analysis using ultra-performance liquid chromatography-MS/MS. Spot UACR was inverse normally transformed and tested for the association with each metabolite or combined, correlated metabolites in covariate-adjusted models that accounted for the study design. 132 metabolites were available for replication in the HyperGEN study (n = 300), and 29 metabolites were available for replication in the Malmö Offspring Study (n = 999). Results. Among 640 named metabolites, we identified 148 metabolites significantly associated with UACR, including 18 novel associations that replicated in independent samples. These metabolites showed enrichment for D-Glutamine and D-Glutamate metabolism and arginine biosynthesis, pathways previously reported for diabetes and insulin resistance. In correlated metabolite analyses, we identified two modules significantly associated with UACR, including a module composed of lipid metabolites related to the biosynthesis of unsaturated fatty acids and alpha linolenic acid and linoleic acid metabolism. Conclusions. Our study identified associations of albuminuria with metabolites involved in glucose dysregulation, and essential fatty acids and precursors of arachidonic acid in Hispanics/Latinos.
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