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The silt deposited in the Yellow River floodplains in China is weak and widely dispersed. In engineering practice, chemically modified agents such as lime and fly ash are frequently employed to enhance the hydro-mechanical behaviour of soils, which however generates significant amounts of CO 2. As an environmentally friendly soil improvement material, Xanthan gum has broad application prospects and is therefore being considered as a solidified material to improve silty soil, which meets the national strategy requirements of ecological protection and high-quality development in the Yellow River Basin. In this study, scanning electron microscope, WP4C apparatus, and an automatic direct shear test system were used to perform several microscopic, water-retention behaviour, and direct shear tests on Xanthan gum-treated silt in drying and wetting paths. According to test results, the differences in shear strength behavior were observed in drying and wetting paths. The average skeleton stress of untreated silt in the drying path is greater than that in the wetting path due to the hysteresis effect, and thus the shear strength in the drying path is higher than that in the wetting path. Xanthan gum-treated silt specimens in the wetting path first were cured at a relative humidity of 47% and temperature of 24°C for seven days, and then were wetted to different water contents. The microstructure of the Xanthan gum-treated silt in the wetting path became firmer, and thus the shear strength was higher than that in the drying path. There is also the hysteretic effect of Xanthan gum-treated silt. However, the curing age is the most important factor affecting this phenomenon. Our findings can serve as a scientific foundation for designing, constructing, and maintaining relevant geotechnical structures in the Yellow River flooded area. • The microstructure of Xanthan-treated silt is firmer than that of untreated silt. • Water retention characteristics of Xanthan-treated silt was obtained in wide suction range. • Shear strength of treated silt in drying and wetting paths was studied quantitatively. • Shear strength of untreated silt in drying path is higher than that in wetting path. • Shear strength of treated silt in wetting path is higher than that in drying path. [ABSTRACT FROM AUTHOR]

A series of wetting tests on unsaturated compacted GMZ07 sodium bentonite, taken from the Gaomiaozi area, Inner Mongolia, China, was performed to investigate the swelling characteristics of the GMZ07 sodium bentonite at temperatures of 5, 20, 60 and 75 °C. The influences of temperature and initial dry density on swelling deformation and swelling pressure were studied by performing a series of constant-stress and constant-volume tests under the wetting condition. The test results showed that the swelling deformation and swelling pressure due to saturation decreased slightly with increasing temperature. A linear relationship was present between the vertical pressure and corresponding saturated void ratio in the semi-logarithmic coordinate at a given temperature; this line is referred to as a state line. Swelling or collapse due to saturation was found to be dependent on the relative location of the initial state between the state line and initial state. The void ratios after saturation at different initial dry densities were close at the same temperature and vertical pressure. [ABSTRACT FROM AUTHOR]

• Water retention characteristics of biopolymer-treated sandy soil in wide suction range. • The microscopic mechanism was explained. • The water retention capacity of treated sandy soil increases as the biopolymer ratio increases. • The water retention capacity of the Gellan gum-treated sandy soil is better than that of Xanthan gum-treated sandy soil. • Based on Fredlund-Xing model, a semi-empirical model was proposed for predicting the soil–water retention curve of biopolymer- treated sandy soil. Soil erosion in the Yellow River basin in China has seriously affected the stability of the foundations of civil engineering structures. Traditional treated materials used for preventing the soil erosion are often harmful to the environment. Biopolymers have been widely used for soil improvement because of their low cost, environmental friendliness, and feasible application. However, most studies on the water-retention behaviour of treated soils conducted to date have focused on the low or high suction range, while few have examined the behaviour over a wide suction range. Converting the saturated state of treated soils into unsaturated state until it is completely dry will lead to changes in the water retention behaviour of biopolymer-treated soils. Therefore, this study investigated variations in the water-retention behaviour and micromechanism of biopolymer-treated sandy soils over a wide range of suction. Specifically, the water-retention behaviour of treated soil was tested using a pressure plate apparatus in the low suction range and a WP4C apparatus in the high suction range. Scanning electron microscopy was also used to evaluate water-retention mechanism of soils treated with different ratios of biopolymer. Biopolymers were found to absorb water to form hydrogels and biofilms, which reduced the pore spaces between soil particles and improved the water storage ability of sandy soils. The water-retention capacity of both Xanthan gum and Gellan gum-treated sandy soils was higher than that of untreated sandy soils, and increased as the biopolymer ratio increased. The water-retention behaviour of the Gellan gum-treated sandy soil were better than that of the Xanthan gum-treated sandy soil. Finally, a prediction model of the soil–water retention curve that considered the biopolymer ratio was proposed based on the Fredlund-Xing model. This study provides a scientific basis for the application of biopolymers to control soil erosion in the Yellow River basin in China. [ABSTRACT FROM AUTHOR]

Primary objective: To investigate the epidemiological characteristics of paediatric inpatients with traumatic brain injury (TBI) in China.Research design: The Chinese Trauma Database (CTD), a nationwide register system based on hospital admission data, contains diagnosis and treatment information for trauma inpatients in over 200 military-managed public-service hospitals in China. Using the ICD-9 coding, the data for children with TBI aged 0–17 years between 2001 and 2007 were retrieved.Methods and procedures: The demographic characteristics, admission time, injury cause, severity and treatment outcomes of paediatric inpatients with TBI were analysed.Main outcomes and results: A total of 26,028 paediatric inpatients with TBI (69.52% male, 30.48% female) were included in the CTD. Motor vehicle traffic (MVT) accidents, falls and assaults were the primary causes of injury. Falls were the leading cause of TBI in children aged 0–4 years, and MVT was the leading cause of TBI in children aged 5–17 years. According to the abbreviated injury scale, 37.20% of the TBI cases were mild, 25.15% were moderate, 24.81% were severe and 12.84% were critically severe.Conclusion: Chinese authorities should develop targeted measures to reduce children injuries based on the leading causes of TBI in the different age groups, particularly MVT, falls and assaults. [ABSTRACT FROM PUBLISHER]

Background: Most migraineurs develop cutaneous allodynia (CA) during migraine, and the underlying mechanism of CA in migraine is thought to be sensitization of the third-order trigeminovascular neurons in the posterior thalamic nuclei. This study aimed to investigate whether the ascending/descending pathway associated with the thalamus is disturbed in migraineurs with CA (MWCA) using effective connectivity analysis of resting-state functional magnetic resonance imaging. Methods: Thirty four migraineurs without aura (14 MWCA and 20 migraineurs without CA (MWoCA)) and 25 matched healthy controls (HC) were recruited in the study. The effective connectivity pathways associated with the posterior thalamus (PTH) were investigated using the Granger causality analysis. We chose bilateral PTH as two individual seeds, and compared MWCA with MWoCA and HC, respectively. Spearman correlation analysis was performed to test the correlation between the abnormal effective connectivity and the allodynia severity of MWCA. Results: Compared with MWoCA, MWCA showed decreased inflows from the left limbic regions and dorsal medial prefrontal cortex (dmPFC) to the ipsilateral PTH, as well as increased inflow from the right ventral medial prefrontal cortex (vmPFC) to the ipsilateral PTH; no significantly different outflows from the bilateral PTH to other regions were found. Compared with HC, MWCA showed increased outflows from the left PTH to the bilateral vmPFC, decreased outflows from the right PTH to the bilateral temporoparietal areas, decreased inflow from the left parietooccipital area to the ipsilateral PTH, and increased inflows from the right dorsolateral prefrontal cortex and the bilateral temporoparietal areas to the right PTH. Correlation analyses revealed that the disturbed connectivities between PTH and cuneus, as well as PTH and middle frontal gyrus were associated with the allodynia severity of MWCA. Conclusions: MWCA demonstrated disrupted effective connection pathways between the PTH and other cortical or subcortical regions that participated in multi-dimentional pain processing. Our findings highlight the dysfunctional ascending and descending pain network at the thalamic-level and may help to illuminate the possible pathophysiologic mechanisms of CA. [ABSTRACT FROM AUTHOR]

Objective Cutaneous allodynia (CA) is a characteristic of central sensitization, predicting migraine progression, and poor response to therapy. The present study aimed to find out the cerebral functional alterations related to the establishment of central sensitization in migraineurs using functional magnetic resonance imaging (fMRI). Design The experiment was performed in 15 migraineurs with Cutaneous allodynia (MWCA) and 19 patients without Cutaneous allodynia (MWoCA) in the interictal phase, and 20 matched healthy controls. Blood oxygen level dependent-fMRI was applied in all subjects when they were given transcutaneous electrical nerve stimulation at the left medial forearm, achieving to a predetermined level of pain sensation (i.e., visual analogue scale [VAS] = 40). Contrast images were then produced to determine whether this disorders present functional changes in the brain during pain processing. Results Demographic and headache characteristics were balanced between groups. The contrast images of both migraine groups comparing to healthy controls exhibited weaker activation of various brain regions (e.g., cerebellum and insulae), which might be relevant to the pathophysiological procedure of migraine. The direct comparison between the two migraine groups revealed that activation in the dorsal pons and contralateral (right) inferior parietal lobule of MWCA subjects were significantly lower than it in MWoCA ones. Conclusions The interictal dysfunction of pain processing pathway may be responsible for (at least relevant to) central sensitization in migraine patients, via abnormal modulations of nociceptive transmission. [ABSTRACT FROM AUTHOR]

Objective: Suicide is a major social and public health problem, but its neurobiology in major depressive disorder is poorly understood. The purpose of this study was to use magnetic resonance diffusion tensor imaging to characterize abnormalities of white matter integrity in major depressive disorder patients with and without a history of suicide attempts., Method: Participants were 52 patients with major depressive disorder, with (N=16) and without (N=36) a history of suicide attempts, and 52 healthy comparison subjects matched for age, gender, education, and ethnicity. Diffusion tensor imaging in a 3.0 Tesla magnetic resonance scanner was performed. Whole-brain voxel-based analysis was used to compare fractional anisotropy across the three groups and analyze the correlation with symptom severity. A region-of-interest analysis was applied to the bilateral hippocampus, thalamus, and lentiform nucleus, Results: Fractional anisotropy was decreased in the left anterior limb of the internal capsule in suicide attempters relative to both nonattempters and healthy comparison subjects, in the right frontal lobe relative to comparison subjects only, and in the right lentiform nucleus relative to nonattempters only. There was no significant correlation with symptom severity., Conclusions: Decreased fractional anisotropy in the left anterior limb of the internal capsule appears to characterize patients with major depressive disorder who have a history of attempting suicide. Longitudinal studies are required to validate this as a potential marker that may inform the development of strategies for reducing suicide.