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Based on the finite element analysis model of the low speed stage of the MW wind turbine gearbox,the fatigue damage of the low speed gearbox is studied. Based on the analysis of the ANSYS-workbench and the ANSYS classic,the stress condition of the low speed level planet carrier of the wind turbine is obtained.The S-N curve of planet carrier is got based on the design specification of GL2010. The fatigue load spectrum of the planet carrier is calculated by the rain flow cycle counting method. Finally,based on the combination of presents a rain flow counting method with Palmagren-Miner damage theory and safety factor to calculate the fatigue damage method by using the n Code/design life software,the fatigue damage and minimum safety factor of the low speed level planet carrier of the wind power gearbox is obtained. The analysis results show that the proposed method is reliable and practical,a more accurate analysis method for the fatigue analysis on planet carrier in MW level wind turbine gearbox is provided and it also has a certain practical significance.

The effects of different concentrations of gallic acid (0 mg/g, 1 mg/g, 2 mg/g, 4 mg/g, and 6 mg/g) on the physicochemical properties of Lateolabrax japonicas myofibrillar protein were studied with 400 W ultrasound. The results showed that gallic acid decreased the particle size, total sulfhydryl group, carbonyl and dimer tyrosine content and Ca2+-ATPase activity (P

Fresh fish are susceptible to degradation and oxidation by endogenous enzymes after death, such as degradation of adenosine triphosphate (ATP) and protein denaturation, resulting in reducing quality and flavor characteristics. To delay the degradation of IMP and to preserve the flavor properties of fish, rosmarinic acid (RA) and epicatechin (EC) were used to inhibit ACP activity. The flavor characteristic was investigated mainly by electronic nose and gas chromatography-mass spectrometry (GC-MS) in sea bass. The results showed that nucleotides content and K value in sea bass treated with RA and EC decreased significantly, and the IMP content increased from 0.61 µg/100 g to 1.70 µg/100 g and 1.39 µg/100 g, respectively, when the flavor to bitterness ratio was the highest, and the degradation of IMP started after 2 d, and the degradation rate coefficients were 0.079 and 0.037, respectively, and both RA and EC could effectively retard the degradation of IMP. A total of 25 volatile substances were detected by GC-MS in the pre-storage period, including 3 aldehydes, 4 alcohols, 2 esters, 3 ethers, 9 amines, and 4 acids and other alkanes. In the middle of storage, 39 volatile substances were detected, including 2 aldehydes, 1 ketone, 6 alcohols, 6 esters, 4 ethers, 10 amines, 10 acids, and other alkanes. 44 volatile substances were detected, including 2 aldehydes, 7 alcohols, 3 esters, 3 ethers, 11 amine substances, and 18 acids and other alkanes in the late storage period. The volatile odors of sea bass treated with RA and EC were more significantly different from that of the control. RA and EC could also slowdown the water loss in the muscle of sea bass. [ABSTRACT FROM AUTHOR]

In order to study the effect of epigallocatechin on the oxidation of myosin in sea bass under microwave heat-ing,differentmass concentrations of epigallocatechin (20,40 /g/mL and 60 /g/mL) were used to inhibit myosin oxidation and study the mechanism of its effect on myosin. EGC could delay the increase of carbonyl content and dityrosine of myosin and the decrease of total sulfhydryl content after microwave treatment. Carbonyl content was reduced by 19.82%- 72.67% compared with the control. AFM showed that the myosin treated with EGC were small and evenly distributed. Microwave induced myosin to unfold and increased fluorescence intensity. EGC maintained the relative stability of the tertiary structures and delayed the increase of fluorescence intensity.Before microwave, low mass concentration EGC (20, 40 /g/mL) significantly increased a helix content and maintained the stability of myosin secondary structure. After microwave, 20 /g/mL EGC maintained the stability of secondary structure. Molecular dynamics simulation showed that RMSF and RMSD value of myosin-EGC decreased, SASA decreased, secondary structure fluctuation decreased. It was found that myosin enhanced the stability of the complex under heating electric field by hydrogen bonding and hydrophobic interaction with EGC. [ABSTRACT FROM AUTHOR]

The effects of gallic chatechin gallate (EGCG) on the digestion properties and protein oxidation of sea bass fillets by microwave hearing was studied. By simulating the gastrointestinal digestion process, the digestibility, particle size, carbonyl, free sulfhydryl, free amino acid contents changes and the morphology of the digestion products were determined. The results showed that digestion of sea bass fillets was basically completed at 40 min, and the protein digestibility was 75.23%. The sea bass slices by EGCG-treating were digested for a longer time, but there was no significant effect on the digestibility. After 120 min of intestinal digestion, the protein digestibility reached 72.13%~76.16%. The carbonyl content in gastric digestion was significantly higher than that in intestinal digestion. After 40 min of digestion in the intestine, the carbonyl content was decreased by 20.76%-30.58%. EGCG delayed the reduction of free sulfhydryl content, and reduced the oxidation level of protein. The particle size in the digestion product system of the EGCG treatment group decreased in concentration-dependent type and reduced the micromorphological aggregation, while reducing the content of free amino acids. [ABSTRACT FROM AUTHOR]

Tourism ecological security (TES) is an important measure of the sustainable development of the tourism industry. It is also an important indicator for evaluating the balance between economic growth and the environmental load of tourism destinations. Therefore, the scientific measurement and examination of TES have important theoretical and practical value in promoting the coordinated and sustainable development of the regional tourism economy and ecological environment. From the perspective of systems theory, based on the driving force–pressure–state–influence–response model, the theoretical framework and index system of China's provincial TES were constructed. The Technique for Order Preference by Similarity to an Ideal Solution method, spatial autocorrelation, traditional and spatial Markov chain, ordinary least squares regression, and geographically and temporally weighted regression model were used to analyze the dynamic evolution characteristics and driving factors of TES. The results indicated the following: (1) Regarding time series, the average value of TES was generally relatively stable with small fluctuations, the differences among provinces exhibited a converging trend, and a significant spatial correlation was observed between the TES of provinces. (2) In terms of dynamic evolution, the transfer of TES types exhibited "path dependence" and "self-locking" effects, meaning the probability of transfer to other types was low, and the status and transfer of TES types were closely related to their neighborhood status. (3) Regarding the driving factors, except for the negative inhibitory effect of environmental pollution on TES, all other variables had a positive promoting effect on TES; however, the effect of each variable in different provinces varied significantly. The results and methods used in this study can enrich the research on TES and provide a theoretical basis and decision-making reference for the healthy and sustainable development of the tourism industry in Chinese provinces. [ABSTRACT FROM AUTHOR]

This study aimed to investigate effects of ellagic acid (EA) and ε-polylysine hydrochloride (ε-PL) on biogenic amines (BAs), volatile compounds and quality of salmon slices stored at 4 °C. The results showed that EA and ε-PL attenuated the production of BAs, retarded the increase of TVC, TVB-N and TBARS. Additionally, water mobility, texture properties of salmon slices were also stabilized by the EA and ε-PL. Volatile compounds including aldehydes, alcohols and hydrocarbons were identified and spoilage-related compounds reduced by the EA and ε-PL, which was related to the inhibition of bacterial, TVB-N and TBA growth by EA and ε-PL. The content of phencthylamine, putrescine, cadaverine, histamine and tyramine in EA-s-PL groups reduced by 46.53%, 54.1%, 26.42%, 31.98% and 45.37% compared to the control group at the end of storage, respectively. Therefore, EA and ε-PL can be applied for inhibiting the increase of BAs and delaying quality deterioration of salmon slices. [ABSTRACT FROM AUTHOR]

As the largest and most important natural terrestrial ecosystem, forest plays a crucial role in reducing the concentrations of greenhouse gases in the atmosphere, mitigating global warming, maintaining the global ecological balance, and promoting global biological evolution and community succession. The accurate and rapid assessment of forest biomass is highly significant for estimating the regional carbon budget and monitoring forest change. In this study, Landsat images and China's National Forest Continuous Inventory data of 1999, 2004, 2009, and 2014 were used to establish extreme gradient boosting (XGBoost) models for forest aboveground biomass (AGB) estimation based on forest type in the Xiangjiang River Basin, Hunan Province, China. Kriging interpolation of the AGB residuals was used to correct the error of AGB estimation. Then, a new XGBoost model was established using the final corrected AGB maps and climate data to estimate the AGB under different climate scenarios during the 2050s and 2070s. The results indicated that AGB estimation using the XGBoost model with correction via Kriging interpolation of the AGB residuals can significantly improve the accuracy of AGB estimation. The total AGB of the study area increased over time from 1999 to 2014, indicating that the forest quality improved in the study area. Under the different climate scenarios, the total AGB during the 2050s and 2070s was predicted to decline continuously with increasing of greenhouse gas emissions, indicating that greenhouse gas emissions have a negative impact on forest growth. The results of this study can provide data support for evaluating the ecological function and value of forest ecosystems, and for formulating reasonable forest management measures to mitigate the effects of climate change. [ABSTRACT FROM AUTHOR]

The effect of ε‐polylysine hydrochloride (ε‐PL) and thymol (TY) in the changes of biogenic amines (BAs) and the quality properties of Illex argentinus was evaluated by measuring the content of BAs, total viable count (TVC), pH, sensory score, and odor change. The experiment was divided into four groups, the control, ε‐PL, TY, and the compound (ε‐PL–TY) group. The results showed BAs‐producing bacteria contained Enterobacteriaceae bacterium, Citrobacter braakii, Klebsiella pneumoniae, Obesumbacterium proteus, Hafnia alvei, Hafnia paralvei, and Hafnia alvei sensu. ε‐PL, TY, and ε‐PL–TY effectively inhibited the increase of BAs content, TBA, pH, and maintained the fresh flavor and sensory properties. ε‐PL–TY was the best to reduce the content of phenethylamine, putrescine, cadaverine, and tyramine by 45.11%, 79.08%, 72.92%, and 63.53% compared with the control at the end of storage. ε‐PL–TY was a promising BAs inhibitor that could protect the edible value and safety of aquatic products. Practical applications: Illex argentinus is susceptible to corruption, and then microorganism in Illex argentinus will produce several biogenic amines, while the combined preservative is the most convenient way to protect its quality after postmortem. Although ε‐polylysine hydrochloride has a better antibacterial activity as a preservative, the single preservative cannot exert a better effect. Thymol is a natural plant ingredient with great antioxidant properties and antibacterial activities, which had an inhibitory synergy with ε‐PL in this study. ε‐polylysine hydrochloride– thymol could be a promising preservative to control the biochemistry activities and protect the edible value of squid. [ABSTRACT FROM AUTHOR]

Summary: In order to obtain the chitosan (CS) coatings with excellent physicochemical properties and antibacterial abilities, the CS coatings were modified by in situ modification nano‐CaCO3 and nano‐TiO2. The coatings were characterised, and their physicochemical properties were measured. The antibacterial mechanism of the coatings was investigated with the Shewanella putrefaciens and Pseudomonas aeruginosa. The nano‐CaCO3/TiO2 can improve the tensile strength and elongation at break of the CS coatings. In addition, the carbon dioxide permeability of the CS coatings is increased after modification by nano‐TiO2. The nano‐CaCO3/TiO2/CS coating can effectively disrupt the integrality of bacterial cell membrane and improve their permeability, reduce the cellular enzyme activities, and affect the synthesis and expression of the bacterial protein. Eventually, the growth and reproduction of S. putrefaciens and P. aeruginosa are inhibited. The in situ modified nano‐CaCO3/TiO2/CS coatings have potential to be applied in the field of preservation of aquatic products. [ABSTRACT FROM AUTHOR]

The effects of chlorogenic acid and quercetin-3-D-galactoside on the decomposition of trimethylamine oxide (TMAO) in squid extract and the main mechanism of inhibition of thermal decomposition were studied. The results indicated that chlorogenic acid and quercetin-3-D-galactoside could inhibit decomposition of TMAO in squid extract. The amount of TMAO was increased by 11.79 and 15.76% in squid extract treated with chlorogenic acid and quercetin-3-D-galactoside from 0 and 2.5 g/L, respectively. The contents of trimethylamine (TMA), dimethylamine (DMA), and formaldehyde (FA) were significantly decreased with increasing contents of chlorogenic acid and quercetin-3-D-galactoside. There were many free radicals in squid extract at high temperatures; however, the free radical signals were weakened after the addition of chlorogenic acid and quercetin-3-D-galactoside therein. This implied that chlorogenic acid and quercetin-3-D-galactoside could inhibit the thermal decomposition of TMAO in squid extract, which was associated with the scavenging of their free radicals. This result provides a theoretical basis for the development and utilization of blueberry leaf extract as an efficient FA inhibitor for aquatic products. [ABSTRACT FROM AUTHOR]

The effects of combined application of lysozyme and resveratrol with chitosan coatings on the quality of Sciaenops ocellatus during refrigerated storage were studied. Physical and chemical indices were periodically analyzed. The chitosan composite coatings were characterized, and the mechanical properties and gas permeability were also measured. The results showed that chitosan coatings could significantly reduce the total viable count (TVC), maintain tissue hardness, chewiness and sensory quality, slow the rate of fat oxidation, and restrain the increases in pH and total volatile basic nitrogen (TVB‐N). Compared with chitosan coatings, the addition of resveratrol and lysozyme had increased the tensile strength and reduced the gas permeability. The lysozyme–resveratrol–chitosan coatings had good preservation properties. The study indicated that the 0.1% lysozyme + 0.2% resveratrol + 1% chitosan group of composite coatings could maintain the quality and extend the shelf life for 8 days compared with the control group during refrigerated storage. [ABSTRACT FROM AUTHOR]

Accurately estimating and mapping forest aboveground carbon density (AGCD) is important for evaluating forest carbon sequestration efficiency and dynamics. This study compares different modelling approaches for estimating AGCD using Landsat 8 Operational Land Imager (OLI) imagery and field forest inventory data. We tested it in Yongshun County, Hunan Province, China. Linear regression (LR) and Random Forest (RF) were used to map crown density (CD). We fitted models with and without CD dummy variables for AGCD estimations. The fitting results and performances of these two types of AGCD models were analysed and compared. There was a difference in the estimation of remote-sensing-based CD models and AGCD models; the coefficients of determination (R2) were 0.66 for LR and 0.84 for RF, respectively, in CD estimations; R2 values were 0.46 for LR and 0.65 for RF, respectively, in AGCD estimations as indicated by basic AGCD models. RF was the best algorithm for CD and AGCD estimations. All of the dummy variable AGCD models provided more accurate AGCD estimates than their basic AGCD counterparts. The dummy variable models (DLR and DRF), which took the observed CD as a dummy variable, were the most accurate for the R2 were 0.61 and 0.85, respectively. The AGCD estimations were significantly overestimated and underestimated by basic AGCD models in thin and dense CD classes, respectively. Nevertheless, none of the AGCD estimates produced by any of the dummy variable models showed this problem. The models that used predicted CD as a dummy variable were more consistent with those that considered observed CD as a dummy variable. The accuracies of AGCD estimations were significantly improved by the dummy variable AGCD models, especially in thin and dense plots; in addition, the CD estimations produced by CD models could be used as dummy variables in AGCD remote-sensing-based models. This work provides that a method considering CD dummy variable in remote sensing-based models was reliable for mapping AGCD at a regional scale. [ABSTRACT FROM AUTHOR]

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BACKGROUND: Among nanomaterials, Ti and ZnO nanoparticles are often chosen as preservation materials because of their antibacterial properties. Chitosan, as a natural biopolymer, has potential because of its abundance, compatibility and antibacterial properties. To improve the physicochemical and preservation properties of in situ SiOx chitosan (CS) composite coating, Ti/ZnO/SiOx CS composite coatings were prepared with Ti‐doped ZnO (Ti/ZnO) nanorods and nanoballs. The composite coating structures were characterized by Fourier transform infrared, X‐ray diffraction and scanning electron microscopy, and their physicochemical and preservation properties were determined simultaneously. RESULTS: The results show that the Ti/ZnO nanoparticles are beneficial to homogeneous dispersion of in situ synthesized nano SiOx in the CS coating, and that Ti/ZnO nanoballs have better dispersion than Ti/ZnO nanorods. Moreover, strong hydrogen bonds are formed among Ti/ZnO nanoparticles and in situ synthesized nano SiOx and CS molecules, and the primary structure of CS is disorganized. Thereby, the gas permeabilities and mechanical properties of the CS coatings are improved due to modification of Ti/ZnO nanoparticles, and the Ti/ZnO nanoballs/SiOx CS composite coating is optimal. The preservation properties of the CS coatings on Sciaenops ocellatus are significantly improved, and those of Ti/ZnO/in situ SiOx CS composite coatings are superior. CONCLUSION: The preservation properties of the CS composite coatings on S. ocellatus are significant, and the Ti/ZnO nanoballs/SiOx CS composite coating is even better. Therefore, the co‐modification method of in situ nanoparticles and antibacterial nanoparticles may be a promising method to improve the preservation properties of CS coatings. © 2019 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Abstract: Colorectal cancer (CRC) is the third most common cancer worldwide, with more than 1.3 million new cases and 690 000 deaths each year. In China, the incidence of CRC has increased dramatically due to dietary and lifestyle changes, to become the fifth leading cause of cancer‐related death. Here, we performed whole‐exome sequencing in 50 rectal cancer cases among the Chinese population as part of the International Cancer Genome Consortium research project. Frequently mutated genes and enriched pathways were identified. Moreover, a previously unreported gene, PCDHB3, was found frequently mutated in 5.19% cases. Additionally, PCDHB3 expression was found decreased in 81.6% of CRC tissues and all eight CRC cell lines tested. Low expression and cytoplasmic localization of PCDHB3 predict poor prognosis in advanced CRC. Copy number decrease and/or CpG island hypermethylation contributes to the pervasive decreased expression of PCDHB3. PCDHB3 inhibits CRC cell proliferation, migration, and epithelial–mesenchymal transition. The tumor‐suppressive effects of PCDHB3 are partially due to inhibition of NF‐κB transcriptional activity through K63 deubiquitination of p50 at lysine 244/252, which increases the binding affinity of inactive p50 homodimer to κB DNA, resulting in competitive inhibition of the transcription of NF‐κB target genes by p65 dimers. Our study identified PCDHB3 as a novel tumor suppressor in CRC via inhibition of the NF‐κB pathway, and its expression and localization may serve as prognostic markers for advanced CRC. Copyright © 2018 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Rho guanine nucleotide exchange factors (RhoGEFs) are proteins that activate Rho GTPases in response to extracellular stimuli and regulate various biologic processes. ARHGEF19, one of RhoGEFs, was reported to activate RhoA in the Wnt‐PCP pathway controlling convergent extension in Xenopus gastrulation. The goal of our study was to identify the role and molecular mechanisms of ARHGEF19 in the tumorigenesis of non‐small cell lung cancer (NSCLC). ARHGEF19 expression was significantly elevated in NSCLC tissues, and ARHGEF19 levels were significantly associated with lymph node status, distant metastasis and TNM stage; Patients with high ARHGEF19 levels had poor overall survival (OS) and progression‐free survival (PFS). Our investigations revealed that ARHGEF19 overexpression promoted the cell proliferation, invasion and metastasis of lung cancer cells, whereas knockdown of this gene inhibited these processes. Mechanistically, ARHGEF19 activated the mitogen‐activated protein kinase (MAPK) pathway in a RhoA‐independent manner: ARHGEF19 interacted with BRAF and facilitated the phosphorylation of its downstream kinase MEK1/2; both the Dbl homology (DH) and Pleckstrin homology (PH) domains of ARHGEF19 were indispensable for the phosphorylation of MEK1/2. Furthermore, downregulation of miR‐29b was likely responsible for the increased expression of ARHGEF19 in lung cancer tissues and, consequently, the abnormal activation of MAPK signaling. These findings suggest that ARHGEF19 upregulation, due to the low expression of miR‐29 in NSCLC tissues, may play a crucial role in NSCLC tumorigenesis by activating MAPK signaling. ARHGEF19 could serve as a negative prognostic marker as well as a therapeutic target for NSCLC patients. [ABSTRACT FROM AUTHOR]

BACKGROUND Shrimp is a low-fat, high-protein aquatic product, and is susceptible to spoilage during storage. To establish an effective method for the quality control of Pacific white shrimp, the effects of polyphenols ( PP) and polysaccharides ( PS) from Porphyra yezoensis on the quality of Pacific white shrimp were assessed during refrigerated storage. Pacific white shrimp samples were treated with 5 g L−1 polyphenols, and 8 g L−1 polysaccharides, then stored at 4 ± 1 °C for 8 days. All samples were subjected to measurement of total viable count ( TVC), pH, total volatile basic nitrogen ( TVB-N), K-value, thiobarbituric acid ( TBA), polyphenol oxidase ( PPO) activity, and were also assessed by sensory evaluation. RESULTS The results showed that PP, PS, and the mixture of polyphenols and polysaccharides ( PP+ PS) could inhibit the increase of total volatile basic nitrogen ( TVB-N), thiobarbituric acid ( TBA) and K-value, and reduce total viable count ( TVC) compared with the control group. PP could also inhibit polyphenol oxidase ( PPO) activity. Sensory evaluation proved the efficacy of PP and PS by maintaining the overall quality of Pacific white shrimp during refrigerated storage. Moreover, PP+ PS could extend the shelf-life of shrimp by 3-4 days compared with the control group. CONCLUSION PP+ PS could more effectively maintain quality and extend shelf-life during refrigerated storage. © 2016 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Uncontrolled growth and distant metastasis are hallmarks of colorectal cancer ( CRC), but the mechanisms are poorly understood. Olfactomedin 1 ( OLFM1), a member of the olfactomedin domain-containing protein family, plays an important role in the development of neurogenic tissues. Recently, OLFM1 deregulation was frequently observed in several cancers, and it was induced in colon cell lines after treatment with the demethylating agent 5-aza-2'-deoxycytidine. However, the function of OLFM1 in CRC remains unknown. In this study, we reanalysed published microarray data and found that OLFM1 was significantly down-regulated in primary CRC samples compared to adjacent non-cancerous tissues. The results of immunohistochemistry indicated that decreased OLFM1 expression was significantly associated with lymph node status ( p = 0.023), distant metastasis ( p < 0.001), and AJCC/ TNM stage ( p = 0.013), and CRC patients with low OLFM1 expression had consistently poor overall survival ( OS; p < 0.001) and progression-free survival ( PFS; p < 0.001). Further analysis demonstrated that OLFM1 was epigenetically silenced in CRC tissues and cell lines via promoter hypermethylation. Overexpression and knockdown of OLFM1 attenuated and increased, respectively, CRC cells' proliferation, migration, and invasion in vitro and metastasis to the lung and liver in vivo. Mechanistically, the promotion of growth and metastasis of CRC cells by silencing of OLFM1 was associated with the activation of the non-canonical NF-κB signalling pathway. OLFM1 interacted with NF-κB-inducing kinase ( NIK; MAP3K14) and repressed the phosphorylation of its downstream substrate Ikappa B kinase alpha ( IKKα). OLFM1 expression was negatively correlated with the phosphorylation level of IKKα in CRC tissue samples. Knockdown of NIK impaired the ability of OLFM1 to repress NF-κB signalling, cell growth or migration. Thus, OLFM1 may be a valuable biomarker and therapeutic target for CRC patients. Copyright © 2016 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

• The molecular mass of TMAOase was 25 kDa. • (+)-Catechin suppressed the activity of TMAOase in a reversible non-competitive inhibition type. • The quenching mechanism of (+)-Catechin against TMAOase is static quenching. • Circular dichroism results showed that secondary structure of TMAOase is altered by (+)-Catechin. Trimethylamine- N -oxide demethylase (TMAOase) is a key enzyme for the decomposition of trimethylamine oxide into formaldehyde. The study investigated the inhibitory effects of (+) - catechin on TMAOase and involved mechanism to minimize the formaldehyde (FA) content of seafood during storage. TMAOase was purified by DEAE-52 cellulose and Sephacryl S-300 chromatography and the inhibitory mechanism of TMAOase was studied by Lineweaver-Burk plots, fluorescence spectroscopy, and circular dichroism. Specific activity of 37 ± 0.7 U/mg was obtained with 205 -fold purification and 15% yield, and molecular mass was 25 kDa. (+)-Catechin was a reversible inhibitor of TMAOase and its induced mechanism was the non-competitive inhibition type. (+)-Catechin binding to TMAOase formed a complex with the binding constant (K sv) of 0.72 × 103 at 298 K. The formation of complex induced the static fluorescence quenching and changes in the conformation of TMAOase, leading to a reduction in the rate of catalysis. [ABSTRACT FROM AUTHOR]

Climate change significantly influences changes in ecological phenomena and processes, such as species distribution and phenology, thus accelerating the rate of species extinction or prosperity. Climate change is considered to be one of the most important threats to global biodiversity in the 21st century and will pose significant challenges to biodiversity conservation in the future. The use of niche modelling to predict changes in the suitable distribution of species under climate change scenarios is becoming a hot topic of biological conservation. In this study, we use data from China's National Forest Continuous Inventory as well as specimen collection data of Cunninghamia lanceolata (Lamb.) Hook to run optimized Maxent models to predict potential suitable distribution of the species in the present day, 2050s, and 2070s under different climate change scenarios in China. In the modeling process, the most important uncorrelated variables were chosen, and the sample-size-adjusted Akaike information criterion (AICc) was used to select the optimal combination of feature type and regularization multiplier. Variable selection reduced the number of variables used and the complexity of the model, and the use of the AICc reduced overfitting. Variables relating to precipitation were more important than temperature variables in predicting C. lanceolata distribution in the optimal model. The predicted suitable distribution areas of C. lanceolata were different for the different periods under different climate change scenarios, with the centroids showing a degree of northward movement. The suitable distribution area is predicted to become more fragmented in the future. Our results reveal the climate conditions required for the suitable distribution of C. lanceolata in China and the likely changes to its distribution pattern in the future, providing a scientific basis for the sustainable management, protection, and restoration of the suitable habitat of this economically important tree species in the context of climate change. [ABSTRACT FROM AUTHOR]

Forest biomass is a major store of carbon and plays a crucial role in the regional and global carbon cycle. Accurate forest biomass assessment is important for monitoring and mapping the status of and changes in forests. However, while remote sensing-based forest biomass estimation in general is well developed and extensively used, improving the accuracy of biomass estimation remains challenging. In this paper, we used China's National Forest Continuous Inventory data and Landsat 8 Operational Land Imager data in combination with three algorithms, either the linear regression (LR), random forest (RF), or extreme gradient boosting (XGBoost), to establish biomass estimation models based on forest type. In the modeling process, two methods of variable selection, e.g., stepwise regression and variable importance-base method, were used to select optimal variable subsets for LR and machine learning algorithms (e.g., RF and XGBoost), respectively. Comfortingly, the accuracy of models was significantly improved, and thus the following conclusions were drawn: (1) Variable selection is very important for improving the performance of models, especially for machine learning algorithms, and the influence of variable selection on XGBoost is significantly greater than that of RF. (2) Machine learning algorithms have advantages in aboveground biomass (AGB) estimation, and the XGBoost and RF models significantly improved the estimation accuracy compared with the LR models. Despite that the problems of overestimation and underestimation were not fully eliminated, the XGBoost algorithm worked well and reduced these problems to a certain extent. (3) The approach of AGB modeling based on forest type is a very advantageous method for improving the performance at the lower and higher values of AGB. Some conclusions in this paper were probably different as the study area changed. The methods used in this paper provide an optional and useful approach for improving the accuracy of AGB estimation based on remote sensing data, and the estimation of AGB was a reference basis for monitoring the forest ecosystem of the study area. [ABSTRACT FROM AUTHOR]

Forest aboveground biomass (AGB) estimation modeling based on remote sensing is an important method for large-scale biomass estimation; the accuracy of the estimation models has been a topic of broad and current interest. In this study, we used permanent sample plot data and Landsat 8 Operational Land Imager (OLI) images of western Hunan. Remote-sensing-based models were developed for different vegetation types, and different crown density classes were incorporated. The linear model, linear dummy variable model, and linear mixed-effects model were used to determine the most effective and accurate method for remote-sensing-based AGB estimation. The results show that the adjusted coefficient of determination (R2adj) and root mean square error (RMSE) of the linear dummy model and linear mixed-effects model were significantly better than those of the linear model; the R2adj increased more than 0.16 and the RMSE decreased more than 2.12 for each vegetation type, and the F-test also showed significant differences between the linear model and linear dummy variable model and between the linear model and linear mixed-effects model. The accuracies of the AGB estimations of the linear dummy variable model and the linear mixed-effects model were significantly better than those of linear model in the thin and dense crown density classes. There were no significant differences in the AGB estimation performance between the linear dummy variable model and linear mixed-effects model; these two models were more flexible and more suitable than the linear model for remote-sensing-based AGB estimation. The results of this study provide a new approach for solving the low-accuracy estimations of linear models. [ABSTRACT FROM AUTHOR]