Mechanism of long-term strength retrogression of silica-enriched Portland cement assessed by quantitative X-ray diffraction analysis

In order to clarify on the driving force of cement long-term strength retrogression, a comprehensive quantitative X-ray diffraction (XRD) analysis were conducted on silica-enriched (60%–80% by weight of cement) cement samples set and cured under the condition of 200°C and 50 MPa with a maximum duration of 180 days. The phase content evolution with time was determined by three different methods on the average of three specimens: the external standard method; the partial or no known crystal structure (PONKCS) method; and the hybrid method. Although the specific phase content estimated by different methods varied slightly, the overall trend of change of all phases were similar. The phase transformation in set cement at high temperature condition is dependent on the slurry composition. In silica-deficient system, tobermorite and amorphous C-S-H were transformed to xonotlite; while in silica-sufficient system, tobermorite and amorphous C-S-H were transformed to gyrolite. These phase transformations involve gradual structural changes of cement hydration products, which may be the driving force of long-term strength retrogression. However, such structural changes can only be detected by XRD once the transformation is complete

An integrated geophysical approach for investigating hydro-geological characteristics of a debris landslide in the Wenchuan Earthquake area

Debris landslides are one of the most widely distributed types of landslides in the Wenchuan earthquake area. The hydro-geological structure characteristics are the fundamental basis for stability evaluation, performing protection and administration of a landslide. The rock and soil mass of a debris landslide was highly non-uniform and preferential seepage paths were normally developed in it. Therefore, in situ identification of the underground water seepage system became particularly important. Recently, investigations on the seepage paths of underground water in debris landslides were restricted to indoor model testing and site observation, which were far from meeting the actual demand for landslide prevention and mitigation. To locate the seepage paths, we conducted survey work on a debris landslide seated in the Xishan Village, Li County, Sichuan Province, China, by combing four different geophysical methods. They were multichannel analysis of surface wave (MASW), electrical resistivity tomography (ERT), ground penetrating radar (GPR) and microtremor survey method (MSM). The geophysical interpretation was verified with field engineering surveys and monitoring data. The results suggested that a dendritic pipe-network seepage system usually developed in debris landslides. Varisized infiltration pipes showed the characteristics of inhomogeneity and concentration of the seepage. This work highlighted that geophysical parameters (shear wave velocity Vs, dielectric constant ε and resistivity value ρ) could provide reliable qualitative and quantitative information about the colluvial layer, bedrock interface, potential sliding surface and underground water seepage system of a landslide. The optimum combination of geophysical methods was suitable to survey the hydro-geological characteristics of debris landslides in the Wenchuan earthquake area

Consolidation considering clogging

In land reclamation projects, the vacuum preloading method has been widely used to strengthen dredged fills by removing water. However, during the improvement process, clogging inevitably occurs in the drains and soils, hindering water drainage and causing inhomogeneous consolidation results. Therefore, it is essential to evaluate the effect of clogging on the consolidation behavior of dredged slurry at different radii. In this study, analytical solutions are derived under an uneven strain assumption to calculate the consolidation in the clogging zone and the normal zone, with time-dependent discharge capacity and clogging in the soil considered. Results calculated by the proposed solutions indicated that the clogging effect slows down the development of consolidation, reduces the final consolidation degree, and increases the difference between consolidations at different radii. It is found that the influence of the clogging effect's varies with the speed of the discharge capacity decay, the value of the initial discharge capacity of the drain, the permeability, and the radius of the clogging zone. Finally, a practical application of the proposed solution is discussed, and the proposed solution is suggested for the calculation of consolidation when treating high-water-content slurry

Prevalence of comorbidities and their associated factors in patients with type 2 diabetes at a tertiary care department in Ningbo, China: a cross-sectional study

Objectives: To determine the prevalence of comorbidities in patients with type 2 diabetes (T2DM) and identify the factors independently associated with comorbidities in a tertiary care department in Ningbo, China.Design: A computerised medical records database was used to conduct a cross-sectional study.Setting The study was conducted in a tertiary care department in Ningbo, China.Participants: The study was conducted on adult patients with T2DM, and it included eight years of data, from 1 January 2012 to 31 December 2019. The primary outcome measure: Comorbidity was defined as the co-existence of at least one other chronic condition, i.e., either a physical non-communicable disease (duration ≥3 months), a mental health condition (duration ≥3 months), or an infectious disease (duration ≥3 months). Results: In total, 4777 patients with T2DM satisfied the eligibility criteria. Over eight years, the prevalence of comorbidities was 93.7%. The odds of comorbidities increased with the age of patients (18–39 years: 1; 40–59 years: odds ratio 2.80, 95% confidence interval 1.98–3.96; 60–69 years: 4.43, 3.04–6.44; and ≥70 years: 10.97, 7.17–16.77). The odds were lower in female patients (0.66, 0.51–0.84), patients residing in rural areas (0.75, 0.59–0.95), and patients without health insurance (0.62, 0.46–0.83). The odds were higher in single/divorced/widowed patients compared to those in married patients (1.95, 1.21–3.12). Conclusions: A large percentage of patients with T2DM in the tertiary care department in Ningbo, China, had comorbidities, and the factors associated with comorbidities were identified. The findings could be used in developing, evaluating, and implementing interventions aimed at improving outcomes in patients with T2DM with comorbidities

Analysis of chromosome karyotype and genome size in echiuran Urechis unicinctus Drasche, 1880 (Polychaeta, Urechidae)

Karyotype and genome size are two primary cytogenetic characteristics of species, which are of great significance to the study of cytogenetics, taxonomy, phylogenesis, evolution as well as molecular biology. However, this basic cytogenetic information in echiurans is lacking. Therefore, we analyzed characteristics of karyotype and genome size in the echiuran worm Urechis unicinctus Drasche, 1880. In this study, coelomic cells of U. unicinctus were used for analyzing the genome size by a flow cytometry with chicken erythrocytes as DNA standard, and the 2C DNA content was determined to be 1.85 pg, which was corresponded to the genome size of 904.58 Mbp approximately. Furthermore, trochophores of U. unicinctus were dissociated and cells were utilized for preparing the chromosomes stained with DAPI, and the karyotype was determined as 2n = 30 (10m + 6sm + 6st + 8t), FN=52. Our data provided the basic cytogenetic information of U. unicinctus, which could be utilized in taxonomic study and whole-genome sequencing in future