Abstract The mechanical properties of rocks in cold regions undergo significant changes as a result of decades of freeze‒thaw cycles with seasonal variations, which can lead to a series of geological ...disasters, such as collapse. This study investigates the evolution of the mechanical characteristics and internal progressive damage characteristics of mixed granite under freeze‒thaw cycling and axial loading. By measuring the mass, wave velocity, and uniaxial compressive strength of rock samples and combining these metrics with acoustic emission (AE) characteristics, the physical and mechanical properties and microfracture development of mixed granite after different numbers of freeze‒thaw cycles were investigated. The results indicate that as the number of freeze‒thaw cycles increases, the longitudinal wave velocity, uniaxial compressive strength, and elastic modulus of the mixed granite decrease nonlinearly, while the peak strain gradually increases. Combined with the stress‒strain curve, the AE characteristics can be divided into four stages. As the number of freeze‒thaw cycles increases, the AE cumulative count decreases, and the AE counts of the four stages are different. The low-frequency-high-amplitude signals first increases and then tends to stabilize, and they only appeared in the third and fourth stages. At the same time, the proportion of the low-frequency ratio gradually increases, and the proportion of the high-frequency ratio decreases. In addition, based on the rise time/amplitude (RA) and average frequency (AF) characteristics and failure modes, it was found that the internal crack types of mixed granite transition from shear cracks to tensile cracks, among which tensile cracks play a crucial role in rock failure.
Through the uniaxial compression test of double parallel fissured layered rock mass, the mechanical properties of layered rock mass with different fissure dip angle, and the characteristics of ...acoustic emission (AE) parameters in the process of fracture are studied. The influence of fissure dip angle on the progressive damage, and macroscopic fracture of layered rock mass is explored. The fracture mode, local stress variation characteristics, and stress field evolution law of fissured layered rock mass are analyzed from a mesoscopic point of view. The results show that with the increase of the fissure dip angle
α
, the peak strength and the elastic modulus of the layered rock mass decrease first and then increase. The low frequency-high amplitude (LF-HA) signals of AE all appear in the crack propagation stage. With the increase of fissure dip angle
α
, the LF-HA signal ratio increases first, then decreases and then increases, and shows significant stage characteristics. The cracks are mainly generated around the relatively low strength A rock and prefabricated fissures, and all pass through the interface between A rock and B rock. Eight types mesoscopic displacement field models are found, and the final failure mode of the model is tensile-shear mixed failure. The upper and lower regions of the fissure are tensile stress areas, while the left and right regions are compressive shear stress areas, which are distributed in a “butterfly” type. The stress difference at the fissure tip is negatively correlated with the mechanical parameters of the layered rock mass.
Article Highlights
AE characteristic parameters can be used to reveal the internal damage of fissured layered rock mass.
Lithology and fissured dip angle jointly determine the mesoscopic fracture type of layered rock mass.
The interface and fissures of layered rock mass change the distribution of displacement and stress of rock mass.
Memory T (Tm) cells are a subpopulation of immune cells with great heterogeneity. Part of this diversity came from T cells that were primed with different viruses. Understanding the differences among ...different viral-specific Tms will help develop new therapeutic strategies for viral infections.
In this study, we compared the transcriptome of Tm cells that primed with CMV, EBV and SARS-CoV-2 with single-cell sequencing and studied the similarities and differences in terms of subpopulation composition, activation, metabolism and transcriptional regulation.
We found that CMV is marked by plentiful cytotoxic Temra cells, while EBV is more abundant in functional Tem cells. More importantly, we found that CD28 and CTLA4 can be used as continuous indicators to interrogate the antiviral ability of T cells. Furthermore, we proposed that REL is a main regulatory factor for CMV-specific T cells producing cytokines and plays an antiviral role.
Our data gives deep insight into molecular characteristics of Tm subsets from different viral infection, which is important to understand T cell immunization. Furthermore, our results provide basic background knowledges for T cell based vaccine development in future.
Cytomegalovirus retinitis is a severe, vision-threatening opportunistic infection in an immunodeficient population. Reports on cytomegalovirus retinitis in hematopoietic stem cell transplant ...recipients due to severe aplastic anemia have been scant. This study assessed the risk of cytomegalovirus retinitis in relation to the pre-transplant status of severe aplastic anemia patients.
We conducted a retrospective nested case-control study of cytomegalovirus retinitis among severe aplastic anemia patients receiving allogeneic hematopoietic stem cell transplants in a tertiary care institution that attends severe aplastic anemia patients from southern China from January 1, 2013 to December 31, 2018. Each cytomegalovirus retinitis case was matched with four controls without cytomegalovirus retinitis by age and gender. Thirteen pre-transplant parameters were chosen to compare the risk factor levels between the cases and controls. Multivariable logistic regressions were used to estimate the odds ratios (ORs) and 95% confidence intervals (CIs).
A total of 361 severe aplastic anemia patients received hematopoietic stem cell transplants in the study period 2013-2018 in our medical institution, and 31 (8.58%) developed cytomegalovirus retinitis. Cytomegalovirus retinitis was diagnosed in the median of 148 days after transplantation. We confirmed platelet refractoriness more frequently in cases than in controls (
= 0.0005). Compared with human leukocyte antigen-matched sibling donors, alternative donors were significantly more prone to cytomegalovirus retinitis (
= 0.0009). After stepwise selection in multivariate logistic regression, platelet refractoriness (OR 5.41, 95% CI 1.98-15.39), haploidentical donor (OR 7.46, 95% CI 2.19-34.87), and unrelated donor (OR 8.38, 95% CI 2.30-41.34) were associated with an increased risk of cytomegalovirus retinitis.
Pre-transplant platelet refractoriness and alternative donors were significant predictors of cytomegalovirus retinitis in severe aplastic anemia recipients. These results highlight the importance of accounting for existing risks while developing prevention strategies and preemptive treatment for severe aplastic anemia recipients. We recommend that the platelet count be closely monitored and thrombopoietin be properly applied during the period when cytomegalovirus retinitis is prone to occur.
The dynamic interaction between the CMV virus and host immune response remains obscure, thus hindering the diagnosis and therapeutic management of patients with HSCT. The current diagnosis of CMV ...viremia depends on viral load estimation. Medical intervention based on viral load, can be unnecessary or poorly timed for many patients. Here we examined the clinical features and blood samples of patients with HSCT and assessed the CMV reactivation kinetics and corresponding CMV antigen-specific T-cell response in individual patients based on a peptide pool stimulation T-cell assay, which showed that CMV-specific CD8+ T cells were more suitable to be a diagnosis indicator for suppressing CMV reactivation. Using ROC analysis, we defined and verified a CMV-specific CD8+ T-cell counts threshold (925 cells/106 PBMCs) as an indicator of CMV reactivation post-HSCT, and suggested that use of this threshold would provide more accurate guidance for prompt medication and better management of CMV infection post-HSCT.
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•CMV reactivation and tailored specific T-cell response kinetics were established•CMV reactivation started at d25 (d17-d35) and last for 51 (33–63) days•CMV-specific CD8+ T cells are responsible for suppressing CMV reactivation•CMV-specific CD8+ T-Threshold was defined as 925/106 PBMC
Health sciences; Immunology; Immune system; Virology; Stem cells research; Mathematical biosciences.
The effects of different SARS-CoV-2 vaccinations and variant infection histories on imprinting population immunity and their influence on emerging escape mutants remain unclear. We found that Omicron ...(BA.1) breakthrough infection, regardless of vaccination with two-dose mRNA vaccines (M-M-o) or two-dose inactivated vaccines (I-I-o), led to higher neutralizing antibody levels against different variants and stronger T-cell responses than Delta breakthrough infection after two-dose inactivated vaccine vaccination (I-I-δ). Furthermore, different vaccination-infection patterns imprinted virus-specific T-cell differentiation; M-M-ο showed higher S/M/N/E-specific CD4
T cells and less portion of virus-specific CD45RA
CD27
CD8
T cells by ex vivo assay. Breakthrough infection groups showed higher proliferation and multi-function capacity by in vitro assay than three-dose inactivated vaccine inoculated group (I-I-I). Thus, under wide vaccination coverage, the higher immunogenicity with the Omicron variant may have helped to eliminate the population of Delta variant. Overall, our data contribute to our understanding of immune imprinting in different sub-populations and may guide future vaccination programs.
The immunoprotective components control COVID-19 disease severity, as well as long-term adaptive immunity maintenance and subsequent reinfection risk discrepancies across initial COVID-19 severity, ...remain unclarified. Here, we longitudinally analyzed SARS-CoV-2-specific immune effectors during the acute infection and convalescent phases of 165 patients with COVID-19 categorized by severity. We found that early and robust SARS-CoV-2-specific CD4
and CD8
T cell responses ameliorate disease progression and shortened hospital stay, while delayed and attenuated virus-specific CD8
T cell responses are prominent severe COVID-19 features. Delayed antiviral antibody generation rather than titer level associates with severe outcomes. Conversely, initial COVID-19 severity imprints the long-term maintenance of SARS-CoV-2-specific adaptive immunity, demonstrating that severe convalescents exhibited more sustained virus-specific antibodies and memory T cell responses compared to mild/moderate counterparts. Moreover, initial COVID-19 severity inversely correlates with SARS-CoV-2 reinfection risk. Overall, our study unravels the complicated interaction between temporal characteristics of virus-specific T cell responses and COVID-19 severity to guide future SARS-CoV-2 wave management.
To investigate the safety, feasibility and long-term outcomes of laparoscopic complete mesocolic excision for the transverse colon cancer.
Clinical data of 61 patients who underwent laparoscopic ...complete mesocolic excision for transverse colon cancer (transverse group) in our department from January 2011 to January 2014 were retrospectively analyzed, which were compared with those of 155 patients undergoing laparoscopic complete mesocolic excision for ascending colon cancer (ascending group) and 230 patients undergoing laparoscopic complete mesocolic excision for sigmoid colon cancer (sigmoid group). Differences in operative details, postoperative recovery, postoperative complications and long-term survival among 3 groups were evaluated.
No significant differences in the baseline information were found among 3 groups(all P>0.05). The average operative time was significantly longer in transverse group as compared to ascending group and sigmoid group (192.1±58.7) min vs. (172.2±54.7) min and (169.1±53.6) min(
Heavy metal contamination is widespread in the environment and has resulted in numerous adverse consequences for the ecosystem. Ureolytic microorganisms are known to immobilize heavy metals by ...co-precipitation with calcium carbonates, which are formed during microbial hydrolysis of urea. In this work, we described a novel halophilic ureolytic bacterium (Exiguobacterium sp. JBHLT-3) and examined the relationship between ureolytic-driven mineralization of CaCO3 and heavy metal mitigation. The growth of strain JBHLT-3 occurred at salinities between 3 and 12% with an optimum at 6%. This strain was capable of precipitating calcite and vaterite under non-growth conditions. Lead (Pb) was selected as a model heavy metal for this study and amended into the bio-precipitation systems at a starting concentration of 1 mM. The strain JBHLT-3 efficiently removed Pb from saline solutions via incorporation within microbially-induced calcium carbonates. Mineralogical analysis showed that calcite had higher uptake of Pb2+ than vaterite. The increasing solution salinity progressively increased the vaterite fraction in the bio-precipitates but reduced the removal efficiency of Pb2+. Nevertheless, the removal efficiency could be still as high as 89% in the cultures incubated in a 12% salinity medium. Our results highlight the positive role of halophilic ureolytic microbes in remediating heavy metal-contaminated saline environments.
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•A novel halophilic ureolytic bacterium, Exiguobacterium sp. JBHLT-3, has the capacity to induce CaCO3 precipitation.•Removal of Pb2+ from saline solutions is initiated by microbially-induced carbonation.•Calcite has higher uptake of Pb2+ than vaterite.•Solution salinity reduces the removal efficiency of Pb2+.
