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Aliphatic polycarbonates (APCs) have become an essential packaging material because of their renewability, biodegradability, and biocompatibility. In this study, a series of high molecular weights APCs have been successfully synthesized using dimethyl carbonate (DMC) and different lengths of aliphatic diols with even carbon (n-CH2 = 4–12) via melt polymerization. Thermal properties, isothermal crystallization behavior, crystal structure, and scale of microstructure of APCs indicated that the flexibility and crystallization of molecular chains gradually increased with the increasing number of methylene groups of repeating units. However, due to the rigidity of ester group was higher than methylene group, and crystallization could increase the rigidity of chain segments, yielding strength and Young's modulus of APCs decreased first and then gradually increased with the increasing number of methylene groups in the repeating units. Furthermore, the scale of microstructure indicated that Brill transition increased the distance between intermolecular chains. Therefore, although the trans-gauche coexistence chain conformation simultaneously decreased the rigidity and crystallization of chain segments, barrier property of poly(octamethylene carbonate) with Brill transition was similar to long-chain APCs because of the lengthened diffusion path. The analytical mechanism of structure-performance relationship from the viewpoint of molecular interactions and chain structure will provide an entirely new thought for developing new barrier materials. [ABSTRACT FROM AUTHOR]

Despite advances in parameters back-analysis of surrounding rocks, training and testing data have to be developed for individual projects because they require different support systems and are executed under different geological conditions, resulting in a tedious back-analysis process and low efficiency. In this study, the effects of support structure on surrounding rock were simulated using the support pressure, and a general parameters back-analysis database was created to rapidly determine the parameters of tunnels with different surrounding rock conditions, of varying depths, and requiring different support systems. To achieve this, the excavations of 1000 groups of tunnels with random depths and rock parameters were calculated using such methods as numerical simulation and machine learning, and a general back-analysis database were created. In the database, in situ stress and deformation were used as the input data, and the rock parameters were regarded as the output data. Subsequently, training and testing were executed using the GA-BP neural network to generate a trained parameters back-analysis model, with its reliability being verified using 13 engineering cases. Additionally, parameters back-analysis and tunnel excavation simulations were applied to the Xinjiang Water Diversion Project and the Xiaoqian Tunnel; the errors were negligible compared with the measured displacement. The results demonstrated that the simulation of the effects of support systems on surrounding rock using the support pressure was rational, and the dimensionless deformation can eliminate the effects of differences in tunnel shape and diameter. The database can be used to determine the surrounding rock parameters of tunnels in different projects. [ABSTRACT FROM AUTHOR]

Water–rock interaction is a common phenomenon in rock mass engineering. Water–rock interaction alters the mineralogical and microstructural properties of a rock mass and leads to engineering problems such as leakage, deformation, and failure of a rock mass. To investigate the local leakage in the limestone reservoir, limestone specimens were taken from the underground chamber. In this study, two test conditions were designed: with and without regular replacement of the reservoir water condition. The results indicated that the porosity increased sharply in the early stages of the soaking. But, the rate of increment dropped after 120 d (regular replacement of reservoir water condition) and 90 d (unchanged reservoir water condition), respectively. The pore in the rock was 4.50 mm deep, while the reservoir water was replaced regularly, which is 1.54 times that of the unchanged reservoir water condition (i.e., 2.50 mm), in 360 soaking days. Relatively, the renewal of reservoir water enhanced the chemical reaction. The water–rock interaction altered the mineralogical composition, spatial structure of the crystal, and pore structure of the rock. The change in the longitudinal wave velocity Vm measures the state of pore development. The porosity evolution model for limestone rock was established by considering the impact of dissolution on the spatial structure of the crystal skeleton. The model accurately predicted the variation trend of porosity in the limestone rock under water–rock interaction. [ABSTRACT FROM AUTHOR]

Variation in normal blood cells during chemotherapy has not been recognised as a risk factor guiding chemotherapy in childhood acute lymphoblastic leukaemia (ALL). This study aims to explore whether variations in normal haematopoiesis determine prognosis as well as to improve risk-stratified treatment in childhood ALL. A retrospective study of 279 cases of ALL treated with the CCCG-ALL-2015 regimen in the Division of Pediatric Blood Diseases Center, Institute of Hematology & Blood Diseases Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, from May 2015 to January 2017 was performed to analyse the prognostic impact of blood cell levels on day 19 of induction therapy by Kaplan-Meier method. Patients with childhood ALL with absolute neutrophil count (ANC) ≤ 90 cells/μl, absolute monocyte count (AMC) ≤ 10 cells/μl or absolute lymphocyte count (ALC) ≤ 1000 cells/μl on day 19 of induction therapy had a lower event-free survival (EFS) rate than those with higher values (all P < 0.05). Multivariate analysis confirmed that ANC ≤ 90 cells/μl and ALC ≤ 1000 cells/μl were independent adverse prognostic factors (HR = 1.981 and 2.162, respectively, both P < 0.05). Among patients with minimal residual disease (MRD) < 1% on day 19 of induction therapy, those with ANC ≤ 90 cells/μl had lower EFS than those with ANC > 90 cells/μl (70.8 ± 6.1% vs 86.4 ± 3.1%, P = 0.001). In the subgroup with the BCR/ABL1 fusion gene, patients with ANC ≤ 90 cells/μl on day 19 of induction therapy also had lower EFS than those with ANC > 90 cells/μl (34.4 ± 25.2% vs 25.0 ± 21.7%, P = 0.041). ANC and ALC during induction therapy are independent prognostic factors for childhood ALL. ANC contributes to guiding the prognosis of patients with low-level MRD or the BCR/ABL1 fusion gene. [ABSTRACT FROM AUTHOR]

This study retrospectively analyzed the clinical outcome of 172 children with newly diagnosed severe aplastic anemia (SAA) between January 2008 and April 2018, who received rabbit antithymocyte globulin (ATG) and cyclosporine (CsA) as first-line treatment. The median age at diagnosis was 5 years (range, 1–14). The overall response rates were 22.7%, 45.3%, and 61% at 40 days, 3 months, and 6 months, respectively, after rabbit ATG. In multivariate analysis, mild disease severity was the only predictor of favorable response at 6 months (P = 0.006). In the present study, median follow-up period was 63 months (range, 1–135). The 5-year overall survival (OS) and failure-free survival (FFS) rates were 90.5% and 70.4%. Multivariate analysis showed that erythroid burst-forming units (BFU-E) > 2/105 bone marrow mononuclear cell (BMMNC) (P = 0.037) and time interval before IST ≤ 30 days (P = 0.017) were independent positive predictors for OS, meanwhile BFU-E > 2/105BMMNC (P = 0.029) was the only favorable prognostic factor for FFS. [ABSTRACT FROM AUTHOR]

A correction to the article "Generation of the SCN1A epilepsy mutation in hiPS cells using the TALEN technique" by Wanjuan Chen and colleagues that was published in the 2014 issue is presented.