A new rheological model and its application in mountain tunnelling

The time-dependent features of soft rock, named rheology generally, should be taken into account in the long-term design and maintenance of mountain tunnels. Based on the classic Burger-MC rheological model, a Burger-deterioration rheological model is proposed in this paper and is implemented in the numerical codes FLAC3D. A deterioration threshold and two deterioration ratios are introduced in this model to consider the time-dependent strength deterioration aspect of the rock mass. The proposed model is applied to an engineering instance (Ureshino Tunnel Line I, Nagasaki, Japan) to account for the delayed deformations that occurred after its completion since November 1992. The delayed crown settlement and invert upheaval computed from simulations are featured by an exponential characteristic and a stair-typed characteristic, respectively, which agree well with the in-site monitoring data qualitatively. In addition, the realistic rheological parameters involved in the proposed model can be back-analyzed from the in-site monitoring data

Molecular Simulation of Interactions between High-Molecular-Polymer Flocculation Gel for Oil-Based Drilling Fluid and Clay Minerals

China has abundant shale gas resources with great potential, which may serve as a significant support for the development of a “low-carbon economy”. Domestic shale gas resources are buried deeply and difficult to exploit due to some prevalent issues, such as long horizontal sections, severe development of reservoir fractures, strong sensitivity to water, borehole instability, etc. Compared to water-based drilling fluids, oil-based drilling fluid exhibits better inhibition and good lubricity and is thus broadly used in shale gas drilling, but it is confronted with the challenge of removing the harmful solid phase. Selective chemical flocculation is one of the most effective methods of removing the harmful solid phase in oil-based drilling fluid. In this study, interactions between the flocculation gel for oil-based drilling fluid and clay minerals were investigated by molecular simulation, which revealed the molecular-scale selectivity of the flocculation gel for rock cuttings with negative charges. Calculations showed that the flocculation gel is highly effective for the flocculation of negatively charged cuttings, but it is ineffective for flocculating neutral cuttings. The flocculation gel is not very effective for cuttings with high hydrophilicity, and it is totally ineffective for flocculating cuttings with poor hydrophilicity. Within a limited concentration range, the flocculation effect can be enhanced by increasing the flocculation gel concentration. The performance of the flocculation gel declined at elevated temperatures

Expression of Green Fluorescent Protein Gene in Somatic Chimeric Chickens Produced by Transplantation of Transfected Chicken Embryonic Fibroblasts

To investigate whether the genetically modified somatic cells can survive and express foreign gene for a long time after being transplanted into avian embryo, chicken embryonic fibroblasts (CEFs) as a cell vehicle for delivering foreign protein were transfected with the green fluorescent protein (GFP) gene, and were introduced into early chicken embryos via blood vessel microinjection at 65-70h of incubation at 38.5°C. The manipulated eggs were continued to incubate at same condition. The chimerisms of the transplanted CEFs were preliminarily observed under fluorescence microscopy at the different stages in the embryos and the hatchlings. Meanwhile, the chimeric positions of the donor CEFs and the expression of GFP were further examined by polymerase chain reaction (PCR) and immunohistochemistry. The results showed that fluorescent-labeled CEFs embed in the different organs of the recipients including brain, heart, liver, intestine, muscle, etc. and can survive in post-hatch chickens for at least 134 days and the GFP gene can be expressed normally. Long-term survival of the donor CEFs in recipient and normal expression of the GFP gene imply that this approach can be explored for continuous production of target protein in the host chicken

Effects of Bacillus coagulans supplementation on the growth performance and gut health of broiler chickens with Clostridium perfringens-induced necrotic enteritis

Abstract Background The poultry industry is in need of effective antibiotic alternatives to control outbreaks of necrotic enteritis (NE) due to Clostridium perfringens. Methods This study was conducted to investigate the effects of feeding Bacillus coagulans on the growth performance and gut health of broiler chickens with C. perfringens-induced NE. Two hundred and forty 1-day-old broiler chicks were randomly assigned to a 2 × 2 factorial arrangement with two dietary B. coagulans levels (0 or 4 × 109 CFU/kg of diet) and two disease challenge statuses (control or NE challenged). Results NE-induced reduction in body weight gain was relieved by the addition of B. coagulans into broiler diets compared with the NE-infected birds. NE infection damaged intestinal morphological structure, promoted intestinal C. perfringens growth and liver invasion, and enhanced anti-C. perfringens specific sIgA concentrations in the gut and specific IgG levels in serum compared with the uninfected birds. NE infection significantly (P < 0.05) decreased mucin-2 (at 14 d post-infection (DPI), toll -like receptor 2 (TLR2, at 7 and 14 DPI), TLR4 (at 7 and 14 DPI), tumor necrosis factor super family 15 (TNFSF15, at 7 and 14 DPI), lysozyme (LYZ, at 14 DPI) and fowlicidin-2 (at 7 and 14 DPI) mRNA levels, whereas it dramatically (P = 0.001) increased IFN-γ mRNA levels at 7 DPI. However, challenged birds fed diets supplemented with B. coagulans showed a significant (P < 0.01) decrease in gut lesion scores, decreased C. perfringens numbers in the cecum and liver, and an increase in fowlicidin-2 mRNA levels in compared with the uninfected birds. In addition, compared with the non-supplemented group, dietary inclusion of B. coagulans improved intestinal barrier structure, further increased specific sIgA levels and alkaline phosphatase (IAP) activity in the jejunum, enhanced the expression of jejunum lysozyme mRNA, and inhibited the growth, colonization, and invasion of C. perfringens; in contrast, it reduced serum-specific IgG concentrations and jejunum IFN-γ mRNA levels. Conclusion These results indicated that dietary B. coagulans supplementation appeared to be effective in preventing the occurrence and reducing the severity of C. perfringens-induced NE in broiler chickens

Genome-wide identification of cancer-specific alternative splicing in circRNA

Abstract Circular RNA (circRNA) is a group of RNA families generated by RNA circularization, which was discovered ubiquitously across different cancers. However, the internal structure of circRNA is difficult to determine due to alternative splicing that occurs in its exons and introns. Furthermore, cancer-specific alternative splicing of circRNA is less likely to be identified. Here, we proposed a de novo algorithm, CircSplice, that could identify internal alternative splicing in circRNA and compare differential circRNA splicing events between different conditions (http://gb.whu.edu.cn/CircSplice or https://github.com/GeneFeng/CircSplice). By applying CircSplice in clear cell renal cell carcinoma and bladder cancer, we detected 4498 and 2977 circRNA alternative splicing (circ-AS) events in the two datasets respectively and confirmed the expression of circ-AS events by RT-PCR. We further inspected the distributions and patterns of circ-AS in cancer and adjacent normal tissues. To further understand the potential functions of cancer-specific circ-AS, we classified those events into tumor suppressors and oncogenes and performed pathway enrichment analysis. This study is the first comprehensive view of cancer-specific circRNA alternative splicing, which could contribute significantly to regulation and functional research of circRNAs in cancers

Significantly enhanced reversibility and mechanical stability in grain-oriented MnNiGe-based smart materials

Guo W, Miao X, Cui J, et al. Significantly enhanced reversibility and mechanical stability in grain-oriented MnNiGe-based smart materials. Acta Materialia. 2024;263: 119530.Materials that undergo a magnetostructural transition (MST) usually exhibit fascinating magnetoresponsive properties, making them an important class of smart materials. However, practical application of this class of smart materials has been hindered by structural degradation as well as large irreversibility of the MST during consecutive thermal and field cycles. Here we report a significant improvement of the reversibility and mechanical stability in grain-oriented MnNiGe-based alloys that were fabricated using a directional solidification method. The preferred grain orientation enables synergistic deformations between neighboring grains during the MST, leading to a substantial reduction in the transition-induced stress concentration. As a result, in situ and ex situ microscopic observations demonstrate a good mechanical stability of the textured alloys across the MST, in strong contrast to conventional MM'X (M, M' = Mn, Fe, Co, Ni; X = Si, Ge) materials with randomly-oriented grains. The detailed transition stages of the MST have also been observed at the microscopic scale, and are reported for the first time in the MM'X family. Besides, a low thermal hysteresis (Delta T-hys) of similar to 4 K was obtained in the textured alloys, which is the lowest Delta T-hys in the MM'X material family. Textured MnNiGe-based alloys show a large reversible isothermal entropy change (>= 35.9 Jkg(-1)K(-1)) in a 5 T field change, which is the highest among typical magnetocaloric materials. Consequently, this work provides a promising strategy for enhancing the cyclic stability of materials with a MST, which may boost their practical applications in solid-state refrigerators, energy harvesters and high-precision actuators

Assembling of the novel Sm2O3@Co magnetic composites for highly efficient electromagnetic wave absorption

Magnetic metals have attracted extensive attention in microwave absorption for comprehensive merits of high magnetic loss and suitability for mass productions. Nevertheless, the applications have been limited by shortcomings of high conductivity and inadequate impedance matching. In this study, we have successfully synthesized a biphasic magnetic Sm2O3@Co composite through a facile one-step precipitation method. The resultant features a well-designed structure with spherical cores and flaky shells, exhibiting highly-tunable absorption performance over 2–18 GHz. Particularly, under 20 wt% filling ratio with paraffin, the Sm2O3@Co composite achieved minimum reflection loss (RLmin) of −30.1 dB and effective absorbing bandwidth (EAB) of 6.22 GHz at only 1.7 mm. The dielectric and magnetic losses could be easily modulated by simply changing the induced Co ratios. Through a systematic study, the microwave absorption mechanisms of the Sm2O3@Co magnetic composite have been comprehensively elucidated. This research offers a fresh perspective on developing highly efficient electromagnetic wave absorbents based on traditional magnetic metals