Study on the limit of moisture content of smouldering humus during sub-surface fires in the boreal forests of China

A sub-surface forest fire is a kind of fire that spreads slowly with no flames and lower temperatures, and threatens the ecosystem and human life. The moisture content of humus is considered to be an important factor in determining fire occurrence and sustaining. The humus of the Larix gmelinii in the Daxing’an Mountains was selected for the experiment, the limit moisture content condition of sub-surface forest fires was determined by an experiment simulating smoldering, and the prediction model of the probability of sub-surface forest fire occurrence was established. The results will be of great significance for the prevention, monitoring, and fighting of sub-surface forest fires in the boreal forest. The results showed that when the moisture content of humus in the upper layer was low, the smoldering process could be self-sustaining at 20%. For deeper layers of a depth of 18 cm, this increased to 30% moisture content of the humus and was the critical depth for sub-surface fires. The moisture content of 40% was a limit to burning where smoldering can only last for a short duration and is then extinguished. When the moisture content of the humus was 20%, the smoldering temperature was higher and the rate of spread was faster, with smoldering being maintained for longer periods at 30% moisture content. The regression prediction model of the highest temperature and vertical rate of spread in a column of humus was correlated to moisture content and depth, and the model significance was good at p < 0.01. Based on moisture content and depth, the occurrence probability prediction model of sub-surface fires has a good correlation (R 2 = 0.93) and high prediction accuracy (AUC = 0.995). The effect of moisture content (Or = 4.008) on the occurrence probability of sub-surface fires is higher than that of depth (Or = 2.948). The results point out that it is necessary to prevent and monitor the occurrence of sub-surface fires when the humus moisture content is less than 40%. In order to reduce the risk of sub-surface fires, the monitoring time of the fire field should be extended after the fire is extinguished due to the slowburning process of the sub-surface fire. Increasing the moisture content of the humus is an important method to reduce the probability and restrain the spread of sub-surface fires

Current and future patterns of forest fire occurrence in China

Forest fire patterns are likely to be altered by climate change. We used boosted regression trees modelling and the MODIS Global Fire Atlas dataset (2003-15) to characterise relative influences of nine natural and human variables on fire patterns across five forest zones in China. The same modelling approach was used to project fire patterns for 2041-60 and 2061-80 based on two general circulation models for two representative concentration pathways scenarios. The results showed that, for the baseline period (2003-15) and across the five forest zones, climate variables explained 37.4-43.5% of the variability in fire occurrence and human activities were responsible for explaining an additional 27.0-36.5% of variability. The fire frequency was highest in the subtropical evergreen broadleaf forests zone in southern China, and lowest in the warm temperate deciduous broadleaved mixed-forests zone in northern China. Projection results showed an increasing trend in fire occurrence probability ranging from 43.3 to 99.9% and 41.4 to 99.3% across forest zones under the two climate models and two representative concentration pathways scenarios relative to the current climate (2003-15). Increased fire occurrence is projected to shift from southern to central-northern China for both 2041-60 and 2061-80

Salvage radiotherapy strategy and its prognostic significance for patients with locoregional recurrent cervical cancer after radical hysterectomy: a multicenter retrospective 10-year analysis

Abstract Objective We aimed to evaluate the clinical efficacy and prognostic significance of intensity-modulated radiotherapy (IMRT)-based salvage concurrent chemoradiotherapy (CCRT) for patients with locoregional recurrence cervical cancer after radical hysterectomy and evaluated two salvage radiotherapy modes—regional RT (involved-field RT combined with regional lymph nodes) and local RT (involved-field RT). Methods Patients were enrolled retrospectively from January 2011 to January 2022 in three medical centers. Clinical outcomes were analyzed using the Kaplan–Meier method and a Cox proportional hazards model. Propensity score (PS) matching analysis was used to compare the two RT groups. Results There were 72 patients underwent IMRT-based salvage CCRT. The 5-year overall survival and progression-free survival rates were 65.9% and 57.6%, respectively. Univariate analysis showed that patients with stump recurrence, a lower systemic inflammation response index (SIRI), only one metastatic lesion, and received regional RT had better prognosis than their counterparts. In multivariate analysis, recurrence site was the independent prognostic factor of OS, and SIRI was that of PFS. After PS matching, there were 15 patients each in the regional RT group and local RT group. The 5-year OS rate of regional RT group was better than that of local RT group (90.9 vs. 42.4, p = 0.021). However, there was no significant difference between them in terms of PFS rate (47.1 vs. 38.1, p = 0.195). Conclusion Locoregional recurrent cervical cancer treated with IMRT-based salvage therapy has a good prognosis. Recurrence site and SIRI were independent prognostic factors. Regional RT may be a better option for patients with locoregional recurrent

Study on the Limit of Moisture Content of Smoldering Humus during Sub-Surface Fires in the Boreal Forests of China

A sub-surface forest fire is a kind of fire that spreads slowly with no flames and lower temperatures, and threatens the ecosystem and human life. The moisture content of humus is considered to be an important factor in determining fire occurrence and sustaining. The humus of the Larix gmelinii in the Daxing&rsquo;an Mountains was selected for the experiment, the limit moisture content condition of sub-surface forest fires was determined by an experiment simulating smoldering, and the prediction model of the probability of sub-surface forest fire occurrence was established. The results will be of great significance for the prevention, monitoring, and fighting of sub-surface forest fires in the boreal forest. The results showed that when the moisture content of humus in the upper layer was low, the smoldering process could be self-sustaining at 20%. For deeper layers of a depth of 18 cm, this increased to 30% moisture content of the humus and was the critical depth for sub-surface fires. The moisture content of 40% was a limit to burning where smoldering can only last for a short duration and is then extinguished. When the moisture content of the humus was 20%, the smoldering temperature was higher and the rate of spread was faster, with smoldering being maintained for longer periods at 30% moisture content. The regression prediction model of the highest temperature and vertical rate of spread in a column of humus was correlated to moisture content and depth, and the model significance was good at p &lt; 0.01. Based on moisture content and depth, the occurrence probability prediction model of sub-surface fires has a good correlation (R2 = 0.93) and high prediction accuracy (AUC = 0.995). The effect of moisture content (Or = 4.008) on the occurrence probability of sub-surface fires is higher than that of depth (Or = 2.948). The results point out that it is necessary to prevent and monitor the occurrence of sub-surface fires when the humus moisture content is less than 40%. In order to reduce the risk of sub-surface fires, the monitoring time of the fire field should be extended after the fire is extinguished due to the slow-burning process of the sub-surface fire. Increasing the moisture content of the humus is an important method to reduce the probability and restrain the spread of sub-surface fires

Modelling ecosystem structure and trophic interactions in a typical cyanobacterial bloom-dominated shallow Lake Dianchi, China

Lake Dianchi is the largest shallow lake in Yunnan-Guizhou plateau and the sixth largest one in China. The lake has been experiencing cyanobacterial blooms in the last two decades. Although a few studies have investigated the tempo-spatial dynamics of cyanobacterial blooms and their underlying mechanisms, knowledge regarding the food web structure and trophic interactions in bloom-dominated ecosystems is scarce. In the present study, an Ecopath model was developed to assess the entire lake ecosystem on the basis of historical and survey data obtained between 2009 and 2010 at Lake Dianchi. The results showed that the aggregation of flows sensu Lindeman refers to six trophic levels (TLs), and most biomasses and trophic flows were primarily concentrated at the first three levels. About 77.5% of the trophic flows from TLI to TLII originated from detritus, whereas high proportions of under-utilised zooplankton biomass returned to the detritus because of low transfer efficiencies (2.9%) in TLII. The microbial loop was considered to be involved in linking the transfer between detritus and TLII. In addition, low values of connectance index and average mutual information implied that the food web tended to be lost in information diversity and had a less complicated structure. High cycling flows concentrated in the microbial loop reflected that the ecosystem enhanced recycling to forms positive feedback by which ecosystem locked the nutrients and promoted the inflation of biomass in plankton communities. Thus, Dianchi Lake was clearly thought to be a bottom-up control ecosystem. These characteristics of the food web partly explained why cyanobacterial blooms were exceptionally heavy and durable in this lake. Finally, the implications of artificially stocking filter-feeding fish (bighead and silver fish) and exotic zooplantivorous icefish on the ecosystem structure and function are discussed herein. (C) 2014 Published by Elsevier B.V

Influence of Terrain Slope on Sub-Surface Fire Behavior in Boreal Forests of China

In recent years, the influence of extreme weather patterns has led to an alarming increase in the frequency and severity of sub-surface forest fires in boreal forests. The Ledum palustre-Larix gmelinii forests of the Daxing’an Mountains of China have emerged as a hotspot for sub-surface fires, and terrain slope has been recognized as a pivotal factor shaping forest fire behavior. The present study was conducted to (1) study the effect of terrain slope on the smoldering temperature and spread rate using simulated smoldering experiments and (2) establish occurrence probability prediction model of the sub-surface fires’ smoldering with different slopes based on the random forest model. The results showed that all the temperatures with different slopes were high, and the highest temperature was 947.91 °C. The spread rates in the horizontal direction were higher than those in the vertical direction, and the difference increased as the slope increased. The influence of slope on the peak temperature was greater than that of spread rate. The peak temperature was extremely positively correlated with the slope, horizontal distance and vertical depth. The spread rate was extremely positively correlated with the slope. The spread rate in the vertical direction was strongly positively correlated with the depth, but was strongly negatively correlated with the horizontal distance; the horizontal spread rate was opposite. The prediction equations for smoldering peak temperature and spread rate were established based on slope, horizontal distance, and vertical depth, and the model had a good fit (p 0.9) and high prediction accuracy (accuracy > 80%). The study proved the effect of slope on the characteristics of sub-surface fire smoldering, explained the variation in peak temperature and spread rate between different slopes, and established the occurrence prediction model based on the random forest model. The selected models had a good fit, and prediction accuracy met the requirement of the sub-surface fire prediction

Development of a Bispecific Nanobody Targeting CD20 on B-Cell Lymphoma Cells and CD3 on T Cells

B-cell lymphoma is a group of malignant proliferative diseases originating from lymphoid tissue with different clinical manifestations and biological characteristics. It can occur in any part of the body, accounting for more than 80% of all lymphomas. The present study aimed to construct bispecific single-domain antibodies against CD20 and CD3 and to evaluate their function in killing tumor cells in vitro. A Bactrian camel was immunized with a human CD20 extracellular peptide, and the VHH gene was cloned and ligated into a phagemid vector to construct the phage antibody display library. A phage antibody library with a size of 1.2 &times; 108 was successfully constructed, and the VHH gene insertion rate was 91.7%. Ninety-two individual clones were randomly picked and screened by phage ELISA. Six strains with the high binding ability to human CD20 were named 11, 30, 71, 72, 83, and 92, and induced expression and purification were performed to obtain soluble CD20 single-domain antibodies. The obtained single-domain antibodies could specifically bind to human CD20 polypeptide and cell surface-expressed CD20 molecules in ELISA, Western blot, and cell immunofluorescence assays. The anti-CD20/CD3 bispecific nanobody (BsNb) was successfully constructed by fusing the anti-CD20 VHH gene with the anti-CD3 VHH and the bispecific single-domain antibody was expressed, purified, and validated. Anti-CD20/CD3 BsNb can specifically bind CD20 molecules on the surface of human lymphoma Raji cells and CD3 molecules on the surface of T cells in flow cytometry analysis and effectively mediate peripheral blood mononuclear cells (PBMCs) target Raji cells with a killing efficiency of up to 30.4%, as measured by the lactate dehydrogenase (LDH) method. The release of hIFN-&gamma; from PBMCs during incubation with anti-CD20/CD3 BsNb was significantly higher than that of the control group (p &lt; 0.01). The anti-CD20/CD3 BsNb could maintain 80% binding activity after incubation with human serum at 37 &deg;C for 48 h. These results indicated the strong antitumor effect of the constructed anti-CD20/CD3 BsNb and laid the foundation for the further development of antitumor agents and the clinical application of anti-CD20/CD3 BsNb

Seasonal dynamics of water bloom-forming Microcystis morphospecies and the associated extracellular microcystin concentrations in large, shallow, eutrophic Dianchi Lake

The increasing occurrence of Microcystis blooms is of great concern to public health and ecosystem due to the potential hepatotoxic microcystins (MCs) produced by these colonial cyanobacteria. In order to interpret the relationships between variations of Microcystis morphospecies and extracellular MC concentrations, the seasonal dynamics of phytoplankton community composition, MC concentrations, and environmental parameters were monitored monthly from August, 2009 to July, 2010. The results indicated that Microcystis dominated total phytoplankton abundance from May to December (96%-99% of total biovolume), with toxic Microcystis viridis and non-toxic Microcystis wesenbergii dominating after July (constituting 65%-95% of the Microcystis population), followed by M. viridis as the sole dominant species from November to January (49%-93%). Correlation analysis revealed that water temperature and nutrient were the most important variables accounting for the occurrence of M. wesenbergii, while the dominance of M. viridis was related with nitrite and nitrate. The relatively low content of MCs was explained by the association with a large proportion of M. viridis and M. wesenbergii, small colony size of Microcystis populations, and low water temperature, pH and dissolved oxygen. The extracellular MC (mean of 0.5 +/- 0.2 mu g/L) of water samples analyzed by enzyme-linked immunosorbent assay (ELISA) demonstrated the low concentrations of MC in Dianchi Lake which implied the low potential risk for human health in the basin. The survey provides the first whole lake study of the occurrence and seasonal variability of Microcystis population and extracellular MCs that are of particular interest for water quality monitoring and management. (C) 2014 The Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences. Published by Elsevier B.V

Analysis of environmental drivers influencing interspecific variations and associations among bloom-forming cyanobacteria in large, shallow eutrophic lakes

Non-diazotrophic Microcystis and filamentous N-2-fixing Aphanizomenon and Dolichosperrnum (formerly Anabaena) co-occur or successively dominate freshwaters globally. Previous studies indicate that dual nitrogen (N) and phosphorus (P) reduction is needed to control cyanobacterial blooms; however, N limitation may cause replacement of non- N-2-fixing by N-2-fixing taxa. To evaluate potentially counterproductive scenarios, the effects of temperature, nutrients, and zooplankton on the spatio-temporal variations of cyanobacteria were investigated in three large, shallow eutrophic lakes in China. The results illustrate that the community composition of cyanobacteria is primarily driven by physical factors and the zooplankton community, and their interactions. Niche differentiation between Microcystis and two N-2-fixing taxa in Lake Taihu and Lake Chaohu was observed, whereas small temperature fluctuations in Lake Dianchi supported co-dominance. Through structural equation modelling, predictor variables were aggregated into &#39;composites&#39; representing their combined effects on species-specific biomass. The model results showed that Microcystis biomass was affected by water temperature and P concentrations across the studied lakes. The biomass of two filamentous taxa, by contrast, exhibited lake-specific responses. Understanding of driving forces of the succession and competition among bloom-forming cyanobacteria will help to guide lake restoration in the context of climate warming and N:P stoichiometry imbalances.</p

Proteomic Analyses Reveal the Mechanism of <i>Dunaliella salina Ds-26-16</i> Gene Enhancing Salt Tolerance in <i>Escherichia coli</i>

<div><p>We previously screened the novel gene <i>Ds-26-16</i> from a 4 M salt-stressed <i>Dunaliella salina</i> cDNA library and discovered that this gene conferred salt tolerance to broad-spectrum organisms, including <i>E</i>. <i>coli</i> (<i>Escherichia coli</i>), <i>Haematococcus pluvialis</i> and tobacco. To determine the mechanism of this gene conferring salt tolerance, we studied the proteome of <i>E</i>. <i>coli</i> overexpressing the full-length cDNA of <i>Ds-26-16</i> using the iTRAQ (isobaric tags for relative and absolute quantification) approach. A total of 1,610 proteins were identified, which comprised 39.4% of the whole proteome. Of the 559 differential proteins, 259 were up-regulated and 300 were down-regulated. GO (gene ontology) and KEGG (Kyoto encyclopedia of genes and genomes) enrichment analyses identified 202 major proteins, including those involved in amino acid and organic acid metabolism, energy metabolism, carbon metabolism, ROS (reactive oxygen species) scavenging, membrane proteins and ABC (ATP binding cassette) transporters, and peptidoglycan synthesis, as well as 5 up-regulated transcription factors. Our iTRAQ data suggest that <i>Ds-26-16</i> up-regulates the transcription factors in <i>E</i>. <i>coli</i> to enhance salt resistance through osmotic balance, energy metabolism, and oxidative stress protection. Changes in the proteome were also observed in <i>E</i>. <i>coli</i> overexpressing the ORF (open reading frame) of <i>Ds-26-16</i>. Furthermore, pH, nitric oxide and glycerol content analyses indicated that <i>Ds-26-16</i> overexpression increases nitric oxide content but has no effect on glycerol content, thus confirming that enhanced nitric oxide synthesis via lower intercellular pH was one of the mechanisms by which <i>Ds-26-16</i> confers salt tolerance to <i>E</i>. <i>coli</i>.</p></div