The pore structure is an important factor affecting reservoir capacity and shale gas production. The shale reservoir of the Longmaxi Formation in the Changning area, Southern Sichuan Basin, is highly heterogeneous and has a complex pore structure. To quantitatively characterize the shale’s pore structure and influencing factors, based on whole rock X-ray diffraction, argon ion polishing electron microscopy observations, and low-temperature nitrogen adsorption-desorption experiments, the characteristics of the shale pore structure are studied by using the Frenkel-Halsey-Hill (FHH) model. The research reveals the following: 1) The pores of the Longmaxi Formation shale mainly include organic pores, intergranular pores, dissolution pores and microfractures. The pore size is mainly micro-mesoporous. Both ink bottle-type pores and semiclosed slit-type pores with good openness exist, but mainly ink bottle-type pores are observed. 2) The pore structure of the Longmaxi Formation shale has self-similarity, conforms to the fractal law, and shows double fractal characteristics. Taking the relative pressure of 0.45 (P/P0 = 0.45) as the boundary, the surface fractal dimension Dsf and the structural fractal dimension Dst are defined. Dsf is between 2.3215 and 2.6117, and the structural fractal dimension Dst is between 2.8424 and 2.9016. The pore structure of micropores and mesopores is more complex. 3) The mineral components and organic matter have obvious control over the fractal dimension of shale, and samples from different wells show certain differences. The fractal dimension has a good positive correlation with the quartz content but an obvious negative correlation with clay minerals. The higher the total organic carbon content is, the higher the degree of thermal evolution, the more complex the pore structure of shale, and the larger the fractal dimension. The results have guiding significance for the characterization of pore structure of tight rocks.

Background and purposePercutaneous autologous bone marrow transplantation (PABMT) is a minimally invasive therapeutic strategy for the treatment of delayed bone union in adults, which has been confirmed by many studies. However, there is no report on PABMT application in pediatric orthopedic surgery. The aim of this article was to analyze the therapeutic effect of PABMT in children with delayed union of limb bone and its influence in relation to delayed bone union therapy, transplantation period, patients’ sex, fracture location, and fracture fixation.MethodsIn this study, 53 patients (aged 3–16 years, with an average age of 6.7 years) with delayed union of long bone (20 femurs, 12 tibiae, 10 humeri, 5 radiuses, 5 ulnas, and 1 fibula) were treated using PABMT. Clinical examination and X-ray were integrated to evaluate the therapeutic effect.ResultsAll 53 patients were followed up for 2–6 years (average time, 3.5 years). Of the 53 patients, 47 (88.7%) were healed, whereas the other 6 (11.3%) were not, and were subsequently treated by autologous bone grafting. In 30 patients who received their first PABMT treatment 6–8 months after fixation, the clinical cure rate, operation times, and healing time were 83.3%, 5.8±0.5 months, and 2.5±0.6, respectively. In the other 23 patients, whose first PABMT treatments were started within 4 to 6 months after fixation, the clinical cure rate, operation times, and healing time were 95.7% (P=0.167), 3.2±0.3 months (P=0.001), and 1.3±0.6 (P=0.001), respectively. The patients’ sex, fracture location, and fracture fixation did not have statistical influence on the clinical efficacy.ConclusionPABMT is a minimally invasive and effective strategy for the treatment of delayed union of limb bone in children. The early surgical treatment facilitates the fracture healing, reduces the number of transplantation, and shortens the course of treatment.

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Transcobalamin (TC) deficiency is a rare autosomal recessive disease characterized by megaloblastic anemia. It is caused by cellular vitamin B12 depletion, which subsequently results in elevated levels of homocysteine and methylmalonic acid. This disease is usually diagnosed by genetic analysis of the TCN2 gene. Here, we described a 2.2-month-old Chinese girl with TC deficiency presenting with diarrhea, fever and poor feeding. Whole-exome sequencing detected a pair of compound-heterozygous mutations in TCN2 gene, c.754-12C>G and c.1031_1032delGA (p.R344Tfs*20). To our knowledge, it is the first time that they were identified and reported in TC deficiency. This study contributes to a better understanding of the TC deficiency, expanding the spectrum of TCN2 mutations in this disorder and also supporting the early diagnosis and proper treatment of similar cases in the future.

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