Modification of Vertical Earth Pressure Formulas for High Fill Cut-and-Cover Tunnels Experimental and Numerical Methods

Te high-flled cut-and-cover tunnel (HFCCT) is a solution to reclaim more useable lands due to the unique landforms of Loess Plateau in northwestern China. Because of the ultrahigh backfll, the estimation of vertical earth pressure will signifcantly afect the design and safety of the cut-and-cover tunnel (CCT). Te current methods for estimating the vertical earth pressure are either to overestimate or underestimate the vertical earth pressure on the top of HFCCT. To more precisely estimate the vertical earth pressure distribution, the vertical earth pressure based on the soil column pressure, �h (h: the height of backfll above the CCT), needs to be properly modifed. Considering diferent infuential factors, four corresponding coefcients are proposed: �0: crosssectional shape of CCT efect, �1: stifness of backfll efect, �2: width of CCT efect, and �3: coupling efect of slope angle, �, and the ratio of B/D. It is found that �0 has little infuence; the �3 and �1 reduce and �2 amplifes the �h. Te corresponding general forms for these coefcients are determined based on fnite element analysis results. A general equation for estimating vertical earth pressure for the HFCCT including these four coefcients is proposed. Meanwhile, this general form is verifed by the numerical analysis results and experimental results for diferent cases. Terefore, this proposed equation is applicable to estimate the vertical earth pressure for existing or newly designed HFCCT. Furthermore, this proposed method can signifcantly reduce the computational work in engineering analysis

Use of the 2A Peptide for Generation of Multi-Transgenic Pigs through a Single Round of Nuclear Transfer

Multiple genetic modifications in pigs can essentially benefit research on agriculture, human disease and xenotransplantation. Most multi-transgenic pigs have been produced by complex and time-consuming breeding programs using multiple single-transgenic pigs. This study explored the feasibility of producing multi-transgenic pigs using the viral 2A peptide in the light of previous research indicating that it can be utilized for multi-gene transfer in gene therapy and somatic cell reprogramming. A 2A peptide-based double-promoter expression vector that mediated the expression of four fluorescent proteins was constructed and transfected into primary porcine fetal fibroblasts. Cell colonies (54.3%) formed under G418 selection co-expressed the four fluorescent proteins at uniformly high levels. The reconstructed embryos, which were obtained by somatic cell nuclear transfer and confirmed to express the four fluorescent proteins evenly, were transplanted into seven recipient gilts. Eleven piglets were delivered by two gilts, and seven of them co-expressed the four fluorescent proteins at equivalently high levels in various tissues. The fluorescence intensities were directly observed at the nose, hoof and tongue using goggles. The results suggest that the strategy of combining the 2A peptide and double promoters efficiently mediates the co-expression of the four fluorescent proteins in pigs and is hence a promising methodology to generate multi-transgenic pigs by a single nuclear transfer

An Investigation into the Evolution Law of Young’s Modulus of Polyurethane Coatings with Diluent Contents by Microstructure-Based Tests

Recent studies have indicated that the addition of a diluent significantly affect its mechanical properties and performance of a coating, but no works have been reported on the influence of diluent content on the Young’s modulus of a coating, and the evolution law between them is also not clear. To address the deficiency, polyurethane coatings (paint samples) with different diluent contents were prepared. Force-displacement curves and microscan images of the coatings were obtained by atomic force microscopy, and the Young’s modulus of the coatings was calculated on the basis of the indentation method, and positron annihilation lifetime spectroscopy was used to test the microstructure of the coatings. The results reveal that: (i) Young’s modulus of the coating initially increase and then decreases with diluent content increasing; (ii) the free-volume aperture size had a greater effect on Young’s modulus by grey correlation analysis

Improvement in the freeze-thaw resistance performance of concretes by a composite phase change material

Concrete is a widely used material for buildings, and its production reached approximately 10 billion m3 in 2022. Half of concrete-related buildings suffer seasonal freeze-thaw action, which causes frequent engineering damage, short service life and enormous economic loss. To improve the freeze-thaw resistance and durability of concretes, we used expanded graphite (EGC14) to encapsulate n-tetradecane (C14) and thus prepared a composite phase change material (EGC14). Scanning electron microscopy (SEM), differential scanning calorimetry (DSC), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) tests indicate that the EGC14 is chemically stable and has excellent phase change capability. Then, five mass ratios of the EGC14 to concrete aggregates were designed to produce phase change concretes (PCCs), named as PCC-EGC14s (0%, 1%, 2%, 3%, and 4%). The PCC-EGC14s′ freeze-thaw resistance performances were systematically tested at different freeze-thaw cycles (FTCs). The test data demonstrate that the EGC14 could effectively keep the transition and capillary pores in the PCC-EGC14s from expanding into easily FTC-damaged macropores. Moreover, the more EGC14 the PCC-EGC14s contain, the less mass loss, and the larger dynamic moduli of elasticity (MOEd) and compressive strengths the PCC-EGC14s have. According to the strength requirement of C20 concretes, the PCC-EGC14 (3%) has the optimal freeze-thaw durability. Therefore, it is suggested for actual engineering applications. Of course, the mix design principle and experimental data of the new PCC-EGC14s in this work are helpful to comprehend the freeze-thaw process and mechanism of concretes and could also provide a critical reference for practical production

Influence of Structural Shape on Earth Pressure for High-Filled Cut-and-Cover Tunnel with and without Load Reduction Based on Discrete Element Method

In the construction of the Loess Plateau in China, high-filled cut-and-cover tunnels (HFCCTs) had solved the problem of the shortage of land resources. However, this type of structure has a large amount of backfill soil, which leads to the problems of ultrahigh earth pressure and safety of the cut-and-cover tunnels (CCTs) lining structure. Previous studies have focused on the load reduction of various flexible materials, ignoring the influence produced by the shape of the CCT structure on the load reduction. Therefore, via a discrete element software, we investigated the changes of vertical earth pressure (VEP), vertical displacement, lateral earth pressure (LEP), and load transfer mechanisms around a HFCCT with consideration to two cases: (1) different shape of CCT structure; (2) the coupling of load reduction using expanded polystyrene (EPS) and the modified shape of the CCT lining structure. The results obtained by the discrete element method (DEM) revealed that an appropriate structural shape influenced the reduction of the VEP above the CCT and that the coupled effects of the load reduction using the EPS and shape modifications of the CCT lining structure could significantly reduce the VEP above the CCT, which enhanced the safety of the CCT. Meanwhile, the optimal values for the shapes of CCTs are derived

Internal curing of high strength concrete based on saturated microporous cenospheres

The development of high-strength concrete is hindered by its substantial autogenous shrinkage. However, the implementation of internal curing technology has been shown to mitigate this autogenous shrinkage of concrete effectively. Nevertheless, the existing internal curing technique encounters issues, including oversized material particles; this heightens disturbance within the concrete and impacts its overall performance. This study used the water-sieving method to propose microporous cenospheres with micrometer-sized pores from the industrial fly ash. Subsequently, a new internal curing material, saturated microporous cenospheres, was prepared by vacuum adsorption. The three additive amounts of saturated microporous cenospheres were added to concrete mixes using the equal volume sand replacement method to study its effect on the autogenous shrinkage and strength of concrete. The results showed that the micron-sized pores of saturated microporous cenospheres were good channels for water release, and the hollow structure inside had ample water storage space. The water absorption rate exhibited by saturated microporous cenospheres reached a significant value of 147.86%. The saturated microporous cenospheres exhibited a water release ability of 11.9% and 99.1% when exposed to humidity levels of 85% and 50%, respectively. The autogenous shrinkage of high-strength concrete was significantly improved by adding saturated microporous cenospheres. The maximum reduction in autogenous shrinkage of high-strength concrete was 87.5%. Although adding saturated microporous cenospheres affected the concrete strength, the concrete strength still met the requirements for use. These results indicate that saturated microporous cenospheres are suitable materials to reduce autogenous shrinkage of high-strength concrete and have great potential for internal curing

Highly efficient generation of GGTA1 biallelic knockout inbred mini-pigs with TALENs.

Inbred mini-pigs are ideal organ donors for future human xenotransplantations because of their clear genetic background, high homozygosity, and high inbreeding endurance. In this study, we chose fibroblast cells from a highly inbred pig line called Banna mini-pig inbred line (BMI) as donor nuclei for nuclear transfer, combining with transcription activator-like effector nucleases (TALENs) and successfully generated α-1,3-galactosyltransferase (GGTA1) gene biallelic knockout (KO) pigs. To validate the efficiency of TALEN vectors, in vitro-transcribed TALEN mRNAs were microinjected into one-cell stage parthenogenetically activated porcine embryos. The efficiency of indel mutations at the GGTA1-targeting loci was as high as 73.1% (19/26) among the parthenogenetic blastocysts. TALENs were co-transfected into porcine fetal fibroblasts of BMI with a plasmid containing neomycin gene. The targeting efficiency reached 89.5% (187/209) among the survived cell clones after a 10 d selection. More remarkably 27.8% (58/209) of colonies were biallelic KO. Five fibroblast cell lines with biallelic KO were chosen as nuclear donors for somatic cell nuclear transfer (SCNT). Three miniature piglets with biallelic mutations of the GGTA1 gene were achieved. Gal epitopes on the surface of cells from all the three biallelic KO piglets were completely absent. The fibroblasts from the GGTA1 null piglets were more resistant to lysis by pooled complement-preserved normal human serum than those from wild-type pigs. These results indicate that a combination of TALENs technology with SCNT can generate biallelic KO pigs directly with high efficiency. The GGTA1 null piglets with inbred features created in this study can provide a new organ source for xenotransplantation research

Organelle proteomic profiling reveals lysosomal heterogeneity in association with longevity

Lysosomes are active sites to integrate cellular metabolism and signal transduction. A collection of proteins associated with the lysosome mediate these metabolic and signaling functions. Both lysosomal metabolism and lysosomal signaling have been linked to longevity regulation; however, how lysosomes adjust their protein composition to accommodate this regulation remains unclear. Using deep proteomic profiling, we systemically profiled lysosome-associated proteins linked with four different longevity mechanisms. We discovered the lysosomal recruitment of AMP-activated protein kinase and nucleoporin proteins and their requirements for longevity in response to increased lysosomal lipolysis. Through comparative proteomic analyses of lysosomes from different tissues and labeled with different markers, we further elucidated lysosomal heterogeneity across tissues as well as the increased enrichment of the Ragulator complex on Cystinosin-positive lysosomes. Together, this work uncovers lysosomal proteome heterogeneity across multiple scales and provides resources for understanding the contribution of lysosomal protein dynamics to signal transduction, organelle crosstalk, and organism longevity