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2.
Front Genet ; 12: 690264, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34335694

RESUMO

Rose is one of the most fundamental ornamental crops, but its yield and quality are highly limited by drought. The key transcription factors (TFs) and co-expression networks during rose's response to drought stress and recovery after drought stress are still limited. In this study, the transcriptomes of leaves of 2-year-old cutting seedlings of Rosa chinensis 'Old Blush' from three continuous droughted stages (30, 60, 90 days after full watering) and rewatering were analyzed using RNA sequencing. Weighted gene co-expression network analysis (WGCNA) was used to construct a co-expression network, which was associated with the physiological traits of drought response to discovering the hub TFs involved in drought response. More than 45 million high-quality clean reads were generated from the sample and used for comparison with the rose reference genome. A total of 46433 differentially expressed genes (DEGs) were identified. Gene Ontology (GO) term enrichment and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis indicated that drought stress caused significant changes in signal transduction, plant hormones including ABA, auxin, brassinosteroid (BR), cytokinin, ethylene (ET), jasmonic acid (JA) and salicylic acid (SA), primary and secondary metabolism, and a certain degree of recovery after rewatering. Gene co-expression analysis identified 18 modules, in which four modules showed a high degree of correlation with physiological traits. In addition, 42 TFs including members of NACs, WRKYs, MYBs, AP2/ERFs, ARFs, and bHLHs with high connectivity in navajowhite1 and blue modules were screened. This study provides the transcriptome sequencing report of R. chinensis 'Old Blush' during drought stress and rewatering process. The study also identifies the response of candidate TFs to drought stress, providing guidelines for improving the drought tolerance of the rose through molecular breeding in the future.

3.
Am J Transl Res ; 13(7): 8040-8048, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34377286

RESUMO

OBJECTIVE: We aimed to compare the efficacy of microsurgical clipping of intracranial aneurysms with that of arterial embolization in the treatment of ruptured anterior circulation aneurysms. METHODS: The clinical data of 68 patients treated in our hospital for ruptured anterior circulation aneurysms between January 2017 and March 2020 were analyzed retrospectively. According to the surgical methods, the patients were divided into two groups: the microsurgical clipping group (30 cases) and the arterial embolization group (38 cases). The following markers were compared between the two groups: Hunt-Hess classification (HHC) grading, aneurysm occlusion rate, and incidence of postoperative complications, length of hospital stay, hospitalization cost, and the scores of the Glasgow Outcome Scale, Modified Rankin Scale, and Barthel Index during the 6-months follow-up after hospital discharge. RESULTS: The cases of HHC grade I and II increased in both groups at hospital discharge (both P<0.05), and there was no intergroup difference in this marker (P>0.05). The complete occlusion rate in the microsurgical clipping group was higher than that in the arterial embolization group (P<0.05). Compared with the microsurgical clipping group, the arterial embolization group had shorter length of hospital stay and higher hospitalization cost (both P<0.05). There was no difference in the total incidence of postoperative complications between the two groups (P>0.05). However, the arterial embolization group had lower incidence of intracranial infection and higher incidence of vasospasm than the microsurgical clipping group (both P<0.05). During the follow-up, the arterial embolization group had better results in terms of the Modified Rankin Scale and Barthel Index results and had more patients with GOS score of 5 points than the microsurgical clipping group (all P<0.05). CONCLUSION: Both microsurgical clipping of intracranial aneurysms and arterial embolization can effectively treat ruptured anterior circulation aneurysms, and the short-term efficacy achieved by these two methods is similar. Compared with microsurgical clipping of intracranial aneurysms, arterial embolization can lead to shorter hospitalization, lower incidence of intracranial infection, and better patients' prognosis and quality of life after the operation. However, the microsurgical clipping of intracranial aneurysms can achieve higher complete occlusion rate, lower incidence of vasospasm, and lower hospitalization cost than arterial embolization.

4.
Ying Yong Sheng Tai Xue Bao ; 32(5): 1825-1834, 2021 May.
Artigo em Chinês | MEDLINE | ID: mdl-34042379

RESUMO

Soil nematode communities play an important role in ecosystem material cycling and energy flow. In this study, soil samples were collected from three rotation systems in southern Ningxia mountainous region, including alfalfa continuous cropping (A-A), alfalfa-corn rotation (A-C), alfalfa-potato rotation (A-P). Soil physicochemical properties, nematode community composition and their metabolic footprints were measured. Compared with the A-A plot, the concentrations of soil organic carbon (SOC) and total nitrogen (TN) were significantly increased by 4.6% and 7.4% for SOC, 4.0% and 5.2% for TN in the A-C and A-P plots, respectively. Soil microbial biomass carbon and nitrogen were significantly higher in the A-C and A-P plots when compared with the A-A plot. The total abundance of soil nematodes in the A-C and A-P plots was higher by 49.5% and 93.7% than that in the A-A plot, respectively, with the dominant trophic group being changed to omnivores-predators from plant parasite. Compared to the A-A plot, the plant parasite index (PPI) was decreased significantly in the A-C and A-P plots, indicating that the harm of plant-parasites was reduced in soil food web. The nematode channel ratio (NCR) in the A-C and A-P plots were higher than that in the A-A plot, indicating that the role of bacterial decomposition was enhanced in soil organic matter decomposition. The maturity index (MI), the total nematode metabolic footprint, enrichment footprint, structure footprint in the A-C and A-P plots were all significantly higher than those in the A-A plot, suggesting that the structure and function of soil food web were more mature and stable, and the productivity and metabolic activity of nematodes were significantly enhanced. In general, the alfalfa-crop rotations improved soil nutrient status and reduced the disturbance degree of soil food web. Furthermore, soil ecosystem developed in the stable and healthy direction, which would be beneficial to the sustainable development of agriculture.


Assuntos
Nematoides , Solo , Animais , Carbono/análise , China , Ecossistema , Medicago sativa
5.
J Microbiol Biotechnol ; 31(6): 840-846, 2021 Jun 28.
Artigo em Inglês | MEDLINE | ID: mdl-33958508

RESUMO

To improve the bile salt and acid tolerance of probiotics against gastrointestinal stresses, we investigated the effects of soybean lecithin and whey protein concentrate (WPC) 80 on the bile salt tolerance of Lacticaseibacillus paracasei L9 using a single-factor methodology, which was optimized using response surface methodology (RSM). The survival rate of L. paracasei L9 treated with 0.3% (w/v) bile salt for 2.5 h, and combined with soybean lecithin or WPC 80, was lower than 1%. After optimization, the survival rate of L. paracasei L9 incubated in 0.3% bile salt for 2.5 h reached 52.5% at a ratio of 0.74% soybean lecithin and 2.54% WPC 80. Moreover, this optimized method improved the survival rate of L. paracasei L9 in low pH condition and can be applied to other lactic acid bacteria (LAB) strains. Conclusively, the combination of soybean lecithin and WPC 80 significantly improved the bile salt and acid tolerance of LAB. Our study provides a novel approach for enhancing the gastrointestinal tolerance of LAB by combining food-derived components that have different properties.


Assuntos
Adaptação Fisiológica/efeitos dos fármacos , Ácidos e Sais Biliares/metabolismo , Lecitinas/farmacologia , Probióticos/metabolismo , Proteínas do Soro do Leite/farmacologia , Ácidos e Sais Biliares/farmacologia , Lactobacillaceae/efeitos dos fármacos , Lactobacillaceae/metabolismo , Modelos Estatísticos , Soja/química
6.
J Biol Chem ; 296: 100624, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33812996

RESUMO

The reduction of insulin resistance or improvement of insulin sensitivity is the most effective treatment for type 2 diabetes (T2D). We previously reported that Nogo-B receptor (NGBR), encoded by the NUS1 gene, is required for attenuating hepatic lipogenesis by blocking nuclear translocation of liver X receptor alpha, suggesting its important role in regulating hepatic lipid metabolism. Herein, we demonstrate that NGBR expression was decreased in the liver of obesity-associated T2D patients and db/db mice. NGBR knockout in mouse hepatocytes resulted in increased blood glucose, insulin resistance, and beta-cell loss. High-fat diet (HFD)/streptozotocin (STZ)-treated mice presented the T2D phenotype by showing increased nonesterified fatty acid (NEFA) and triglyceride (TG) in the liver and plasma and increased insulin resistance and beta-cell loss. AAV-mediated NGBR overexpression in the liver reduced NEFA and TG in the liver and circulation and improved liver functions. Consequently, HFD/STZ-treated mice with hepatic NGBR overexpression had increased insulin sensitivity and reduced beta-cell loss. Mechanistically, NGBR overexpression restored insulin signaling of AMPKα1-dependent phosphorylation of AKT and GSK3ß. NGBR overexpression also reduced expression of endoplasmic reticulum stress-associated genes in the liver and skeletal muscle to improve insulin sensitivity. Together, our results reveal that NGBR is required to ameliorate T2D in mice, providing new insight into the role of hepatic NGBR in insulin sensitivity and T2D treatment.


Assuntos
Diabetes Mellitus Experimental/prevenção & controle , Diabetes Mellitus Tipo 2/prevenção & controle , Resistência à Insulina , Secreção de Insulina , Metabolismo dos Lipídeos , Receptores de Superfície Celular/metabolismo , Animais , Diabetes Mellitus Experimental/etiologia , Diabetes Mellitus Experimental/metabolismo , Diabetes Mellitus Experimental/patologia , Diabetes Mellitus Tipo 2/etiologia , Diabetes Mellitus Tipo 2/metabolismo , Diabetes Mellitus Tipo 2/patologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Fosforilação , Receptores de Superfície Celular/genética , Transdução de Sinais
7.
Sci Adv ; 7(12)2021 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-33731359

RESUMO

Three-dimensional (3D), submillimeter-scale constructs of neural cells, known as cortical spheroids, are of rapidly growing importance in biological research because these systems reproduce complex features of the brain in vitro. Despite their great potential for studies of neurodevelopment and neurological disease modeling, 3D living objects cannot be studied easily using conventional approaches to neuromodulation, sensing, and manipulation. Here, we introduce classes of microfabricated 3D frameworks as compliant, multifunctional neural interfaces to spheroids and to assembloids. Electrical, optical, chemical, and thermal interfaces to cortical spheroids demonstrate some of the capabilities. Complex architectures and high-resolution features highlight the design versatility. Detailed studies of the spreading of coordinated bursting events across the surface of an isolated cortical spheroid and of the cascade of processes associated with formation and regrowth of bridging tissues across a pair of such spheroids represent two of the many opportunities in basic neuroscience research enabled by these platforms.

8.
Oxid Med Cell Longev ; 2021: 8894491, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33505592

RESUMO

Ochratoxin A (OTA) is a common environmental pollutant found in a variety of foods and grains, and excessive OTA consumption causes serious global health effects on animals and humans. Astaxanthin (AST) is a natural carotenoid that has anti-inflammatory, antiapoptotic, immunomodulatory, antitumor, antidiabetes, and other biological activities. The present study is aimed at investigating the effects of AST on OTA-induced cecum injury and its mechanism of action. Eighty C57 mice were randomly divided into four groups, including the control group, OTA group (5 mg/kg body weight), AST group (100 mg/kg body weight), and AST intervention group (100 mg/kg body weight AST+5 mg/kg body weight OTA). It was found that AST decreased the endotoxin content, effectively prevented the shortening of mouse cecum villi, and increased the expression levels of tight junction (TJ) proteins, consisting of occludin, claudin-1, and zonula occludens-1 (ZO-1). AST increased the number of goblet cells, the contents of mucin-2 (MUC2), and defensins (Defa5 and ß-pD2) significantly, while the expression of mucin-1 (MUC1) decreased significantly. The 16S rRNA sequencing showed that AST affected the richness and diversity of cecum flora, decreased the proportion of lactobacillus, and also decreased the contents of short-chain fatty acids (SCFAs) (acetate and butyrate). In addition, AST significantly decreased the expression of TLR4, MyD88, and p-p65, while increasing the expression of p65. Meanwhile, the expression of inflammatory factors including TNF-α and INF-γ decreased, while the expression of IL-10 increased. In conclusion, AST reduced OTA-induced cecum injury by regulating the cecum barrier function and TLR4/MyD88/NF-κB signaling pathway.


Assuntos
Bactérias/classificação , Ceco/efeitos dos fármacos , Regulação da Expressão Gênica/efeitos dos fármacos , Inflamação/tratamento farmacológico , Ocratoxinas/toxicidade , Animais , Bactérias/efeitos dos fármacos , Bactérias/crescimento & desenvolvimento , Bactérias/metabolismo , Bloqueadores dos Canais de Cálcio/toxicidade , Ceco/lesões , Ceco/metabolismo , Ceco/microbiologia , Inflamação/induzido quimicamente , Inflamação/metabolismo , Inflamação/patologia , Camundongos , Camundongos Endogâmicos C57BL , Fator 88 de Diferenciação Mieloide/genética , Fator 88 de Diferenciação Mieloide/metabolismo , NF-kappa B/genética , NF-kappa B/metabolismo , Receptor 4 Toll-Like/genética , Receptor 4 Toll-Like/metabolismo , Xantofilas/farmacologia
9.
Front Oncol ; 10: 575316, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33042848

RESUMO

Objectives: Whether pre-operative biliary drainage (PBD) affects long-term survival of patients with obstructive jaundice with pancreatic ductal adenocarcinoma (PDAC) who underwent pancreaticoduodenectomy is still controversial. Most of the previous research did not include the important total serum bilirubin (TB) level before intervention as well as before surgery. The aim of this study is to evaluate the impact of PBD on long-term survival after considering the TB level. Methods: Data were collected retrospectively from patients with obstructive jaundice who underwent resection of pancreatic head cancer in a high-volume center. X-Tile software and Kaplan-Meier survival analysis were applied to determine the optimal cut-off levels for TB and age based on the minimal probability (P)-value and the largest χ2-value. Multivariate Cox regression analyses were performed after univariate analysis to assess independent prognostic factors for overall survival (OS) and disease-free survival (DFS). Results: Of 426 patients with obstructive jaundice who underwent pancreaticoduodenectomy for resectable pancreatic head cancer during a 7 year period, 242 (56.8%) received PBD and 184 (43.2%) underwent surgery directly. The OS of patients who received PBD was significantly worse than that of patients who did not receive PBD by univariate analysis (median of 16.6 vs. 22.2 months, P = 0.048). After including liver function parameters in the multivariate Cox regression, we found that the use of PBD was not associated with OS or DFS, while TB before intervention >150 µmol/L was an independent adverse prognostic factor for both OS [hazard ratio (HR), 1.42; 95% CI, 1.05-1.91] and DFS (HR, 1.38; 95% CI, 1.08-1.77). Conclusions: In patients with obstructive jaundice with resectable pancreatic head cancer, undergoing PBD before pancreaticoduodenectomy did not impair or benefit survival rates compared with surgery alone. However, TB before intervention >150 µmol/L predicted an unfavorable prognosis, irrespective of the PBD procedure.

10.
Chemosphere ; 259: 127510, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32650172

RESUMO

Intensive application of biochar requires better understanding of their environmental behaviors such as stability, fate, and mobility. The release of bulk biochar into biochar nanoparticles (NPs) may bring risks because of their potential flowing into downstream water bodies with nutrients/containments attached. Low-temperature pyrolyzed biochars, namely fruit tree branch biochar of 350/450/550 °C (FB350, FB450 and FB550), corn straw biochar of 350 °C (CB350) and peanut straw biochar of 350 °C (PB350), were produced, and their NPs were extracted. The yield, elemental composition, mineral composition, surface functional groups and zeta potential of biochar NPs were characterized. Subsequently their suspension stability was evaluated in NaCl and CaCl2 solutions by dynamic light scattering technique. The Hamaker constants and particle interaction energy of the biochar NPs were calculated by adopting Derjaguin-Landau-Verwey-Overbeek theory. For biochar NPs of same feedstock, the stability of FB350/450/550-NPs could be predicted well by their zeta potential values. The types of their surface functional groups were the same while their adsorption intensity differed. The scenarios for biochar NPs of different feedstock sources were different, that is, inconsistent variation was observed between their zeta potential and suspension stability, which were rooted in the variable type and quantity of surface functional groups. In conclusion, feedstock was the most significant factor that influenced the suspension stability of biochar NPs, followed by the pyrolysis temperature and solution chemistry, which were highly dependent on surface potential. The findings provide references for the environmental risk evaluation of biochar NPs and reasonable application of biochar in field.


Assuntos
Carvão Vegetal/química , Nanopartículas/química , Temperatura , Adsorção , Difusão Dinâmica da Luz , Pirólise , Soluções/química , Propriedades de Superfície , Suspensões/química
11.
Ying Yong Sheng Tai Xue Bao ; 31(4): 1365-1377, 2020 Apr.
Artigo em Chinês | MEDLINE | ID: mdl-32530213

RESUMO

The establishment of Medicago sativa artificial grasslands is an important practice of grassland vegetation restoration in the Loess Plateau. Understanding community characteristics of soil microbes and nematodes can provide important information for evaluating and controlling ecolo-gical and environmental effects of vegetation restoration. In this study, we used M. sativa artificial grasslands with four different cultivation years (1, 2, 6 and 12 years) in southern Ningxia mountainous region, with a farmland and a natural grassland as control, to explore changing trends of the two biological communities during artificial grassland restoration in semi-arid region of the Loess Plateau. The results showed that: 1) After the conversion of farmland to M. sativa grassland, Chao1, ACE and Shannon diversity indices of soil bacterial community increased firstly and then decreased, which reached the maximum after six years of M. sativa grassland establishment. For soil fungal community, Shannon diversity index was lower in 6 and 12 year-old M. sativa grasslands than in the other two artificial grasslands, and the community composition differed across restoration years. 2) With the increases of restoration years, the abundance of soil nematodes showed a similar changing trend with Shannon diversity index of bacterial community. The composition of nematode community did not greatly differ between the 6-year-old M. sativa grassland and farmland, while that in 12-year-old artificial grassland was more similar to that in natural grassland. The proportion of bacterivorous and plant-feeding nematodes, as well as plant parasitic index and nematode channel index of nematode community,were increased, while the proportion of fungivores and omnivores-predators and maturity index were decreased. 3) During the restoration, changes in soil organic carbon, total nitrogen and available phosphorus greatly affected soil microbial community, which could further influence soil nematode community. There were significant correlations between dominant microbial phyla and trophic groups of soil nematodes, implying the possible effects of soil microbes on nematode community. In M. sativa artificial grassland with different establishment years, changes in plant biomass and diversity might significantly affect soil nematode and microbial communities through affecting their food conditions.


Assuntos
Nematoides , Solo , Animais , Carbono , China , Pradaria , Medicago sativa , Microbiologia do Solo
12.
Adv Mater ; 32(28): e2001303, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32462694

RESUMO

Origami/kirigami-inspired 3D assembly approaches have recently attracted attention for a variety of applications, such as advanced optoelectronic devices and biomedical sensors. The results reported here describe an approach to construct classes of multiple foldable 3D microstructures that involve deformations that typical conductive materials, such as conventional metal films, cannot tolerate. Atomically thin graphene sheets serve as folding hinges during a process of 2D to 3D conversion via a deterministic buckling process. The exceptional mechanical properties of graphene enable the controlled, geometric transformation of a 2D precursor bonded at selective sites on a prestretched elastomer into folded 3D microstructures, in a reversible manner without adverse effects on the electrical properties. Experimental and computational investigations of the folding mechanisms for such types of 3D objects reveal the underlying physics and the dependence of the process on the thickness of the graphene/supporting films that define the hinges.

13.
Pancreatology ; 20(3): 529-536, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32107192

RESUMO

OBJECTIVES: The influence of preoperative biliary drainage (PBD) for obstructive jaundiced patients before pancreaticoduodenectomy is debated in the past decades. The aim of this study is to assess the impact of preoperative biliary drainage on intraoperative and postoperative outcomes in patients with severely obstructive jaundice. METHODS: Data were collected retrospectively from severely obstructive jaundiced patients with serum total bilirubin level exceeding 250 µmol/L and undergoing pancreaticoduodenectomy from January 2012 to December 2017. The univariate and multivariate analyses were performed to assess independent risk factors for overall postoperative complications. A propensity score-matched (PSM) analysis was performed to adjust baseline characteristics between PBD and direct surgery (DS) groups. After PSM, intraoperative data and postoperative complications were compared between the two groups. RESULTS: A total of 200 patients were included. The rate of overall postoperative complication occurred in 119 (59.5%) patients, with prealbumin <150 mg/L (OR = 3.03; 95%CI = [1.63-5.62]; p < 0.001), ASA (American Society of Anesthesiology score) classification II-III (OR = 2.27; 95%CI = [1.21-4.27]; p = 0.011), and direct surgery (OR = 3.88; 95%CI = [1.67-8.99]; p = 0.002) identified as independent risk factors in multivariate analysis. After PSM, there was similar operative time and intraoperative transfusion between PBD and DS group. However, DS group had a higher incidence of overall postoperative complication (p = 0.005), grades B and C of post-pancreatectomy hemorrhage (PPH) (p = 0.032), and grades B and C of postoperative pancreatic fistula (POPF) (p = 0.045) compared to PBD group. CONCLUSIONS: In this retrospective study, in order to reduce overall postoperative complications, PBD should be performed routinely for those patients with serum total bilirubin level exceeding 250 µmol/L and undergoing pancreaticoduodenectomy.


Assuntos
Drenagem , Icterícia Obstrutiva/terapia , Pancreaticoduodenectomia/efeitos adversos , Complicações Pós-Operatórias/prevenção & controle , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Bilirrubina/sangue , Transfusão de Sangue , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Duração da Cirurgia , Pancreatectomia/efeitos adversos , Fístula Pancreática/epidemiologia , Fístula Pancreática/etiologia , Complicações Pós-Operatórias/epidemiologia , Hemorragia Pós-Operatória/epidemiologia , Pontuação de Propensão , Estudos Retrospectivos , Fatores de Risco , Adulto Jovem
14.
PeerJ ; 8: e8382, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32002329

RESUMO

Background: Ecological stoichiometry (C:N:P ratios) in soil is an important indicator of the elemental balance in ecological interactions and processes. Long-term natural vegetation plays an important role in the accumulation and distribution of soil stoichiometry. However, information about the effects of long-term secondary forest succession on soil stoichiometry along a deep soil profile is still limited. Methods: We selected Ziwuling secondary succession forest developed from farmland as the study area, investigated the concentrations and stoichiometry of soil organic carbon (SOC), total nitrogen (TN), and total phosphorus (TP) at a depth of 0-100 cm along a 90-year succession chronosequence, including farmland (control), grassland, shrub, early forest, and climax forest. Results: SOC and TN concentrations significantly increased with increasing restoration age, whereas soil P concentration remained relatively stable across various successional stages. SOC and TN concentrations decreased with an increase in soil depth, exhibiting distinct soil nutrient "surface-aggregation" (high nutrients concentration in the top soil layer). The soil C:P and N:P ratios increased with an increase in restoration age, whereas the variation of the C:N ratio was small and relatively stable across vegetation succession. The nutrient limitation changed along with vegetation succession, transitioning from limited N in the earlier successional stages to limited P in the later successional stages. Conclusion: Our results suggest that more nitrogen input should be applied to earlier succession stages, and more phosphorus input should be utilized in later succession stages in order to address limited availability of these elements. In general, natural vegetation restoration was an ecologically beneficial practice for the recovery of degraded soils in this area. The findings of this study strengthen our understanding of the changes of soil nutrient concentration and nutrient limitation after vegetation restoration, and provide a simple guideline for future vegetation restoration and reconstruction efforts on the Loess Plateau.

15.
Phys Rev E ; 101(1-1): 012906, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-32069573

RESUMO

We examine the signatures of internal structure emerged from quasistatic shear responses of granular materials based on three-dimensional discrete element simulations. Granular assemblies consisting of spheres or nonspherical particles of different polydispersity are sheared from different initial densities and under different loading conditions (drained or undrained) steadily to reach the critical state (a state featured by constant stress and constant volume). The radial distribution function used to measure the packing structure is found to remain almost unchanged during the shearing process, regardless of the initial states or loading conditions of an assembly. Its specific form, however, varies with polydispersities in both grain size and grain shape. Set Voronoi tessellation is employed to examine the characteristics of local volume and anisotropy, and deformation. The local inverse solid fraction and anisotropy index are found following inverse Weibull and log-normal distributions, respectively, which are unique at the critical states. With further normalization, an invariant distribution for local volume and anisotropy is observed whose function can be determined by the polydispersities in both particle size and grain shape but bears no relevance to initial densities or loading conditions (or paths). An invariant Gaussian distribution is found for the local deformation for spherical packings, but no invariant distribution can be found for nonspherical packings where the distribution of normalized local volumetric strain is dependent on initial states.

16.
Ying Yong Sheng Tai Xue Bao ; 31(8): 2644-2652, 2020 Aug.
Artigo em Chinês | MEDLINE | ID: mdl-34494787

RESUMO

Through quantitatively adjust soil electric field, we investigated the effect of soil electric field on aggregate stability and soil erosion in black soil region of Northeast China with the experiments of wet sieving and rainfall simulation. Results showed that: 1) Soil surface potential absolute value and electric field strength increased with the decreases of electrolyte concentration in bulk solution. Soil electric field strength could reach to 108 V·m-1. 2) With the increase of soil electric field strength, the degree of fragmentation of soil aggregates increased and the mean weight diameter (MWD) decreased sharply first and then kept constant. 3) With decreasing electrolyte concentration and increasing surface potential, the amount of soil loss increased. As the electrolyte concentration was <0.01 mol·L-1, the corresponding soil surface potential was > 210 and 209 mV for Bin-xian and Keshan, respectively, the cumulative amounts of soil loss with rainfall time almost overlapped, suggesting that the electrolyte concentration of 0.01 mol·L-1 was the threshold for soil erosion. 4) There was a linear relationship between soil cumulative loss and MWD. Our results indicated that soil electric field strength increased as the rain enters into the soil, which could induce soil aggregate breakdown and release amounts of fine soil particles. Finally, soil erosion occurred under the driving of flowing water. Our results provided insights into the mechanism underlying soil erosion in the black soil region of Northeast China.


Assuntos
Solo , Água , China , Chuva , Movimentos da Água
17.
J Thorac Dis ; 12(12): 7298-7312, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-33447419

RESUMO

Background: Calculation methods have a critical role in the precise sorting of medical images. Particle swarm optimization (PSO) is a widely used approach in the clinical centers and for other medical applications as it can disentangle optimization errors in attached spaces. In this work, a new model for image segmentation is proposed through an improved optimization algorithm. Methods: A novel multi-objective algorithm was configured, named "multi-objective mathematical programming" (MOMP), based on the normalized normal constraint method (NNCM). In this model, the proposed algorithm was applied to evaluate the robustness of the suggested model through including the synthetic images of objects with various concavities and Gaussian noise. This model segments the individuals' heart and the left ventricle from data sets of sequentially evaluated tomography and magnetic resonance images. To objectively and quantifiably assess the presentation of the medical image segmentations based on regions outlined by experts and the graph cut method, a set of distance and resemblance metrics were implemented. Results: The numerical results obtained in experimental test cases demonstrate the validity and superiority of the proposed model through better segmentation accuracy and stability. Conclusions: The results indicated that the proposed MOMP method can outperform all traditional models in terms of segmentation accuracy and stability, and is thus appropriate for use in medical imaging.

18.
Adv Mater ; 31(52): e1905715, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31721341

RESUMO

3D structures that incorporate high-performance electronic materials and allow for remote, on-demand 3D shape reconfiguration are of interest for applications that range from ingestible medical devices and microrobotics to tunable optoelectronics. Here, materials and design approaches are introduced for assembly of such systems via controlled mechanical buckling of 2D precursors built on shape-memory polymer (SMP) substrates. The temporary shape fixing and recovery of SMPs, governed by thermomechanical loading, provide deterministic control over the assembly and reconfiguration processes, including a range of mechanical manipulations facilitated by the elastic and highly stretchable properties of the materials. Experimental demonstrations include 3D mesostructures of various geometries and length scales, as well as 3D aquatic platforms that can change trajectories and release small objects on demand. The results create many opportunities for advanced, programmable 3D microsystem technologies.

19.
ACS Appl Mater Interfaces ; 11(3): 3482-3492, 2019 Jan 23.
Artigo em Inglês | MEDLINE | ID: mdl-30584766

RESUMO

Development of schemes to form complex three-dimensional (3D) mesostructures in functional materials is a topic of broad interest, thanks to the ubiquitous applications across a diversity of technologies. Recently established schemes in the mechanically guided 3D assembly allow deterministic transformation of two-dimensional structures into sophisticated 3D architectures by controlled compressive buckling resulted from strain release of prestretched elastomer substrates. Existing studies mostly exploited supporting substrates made of homogeneous elastomeric material with uniform thickness, which produces relatively uniform strain field to drive the 3D assembly, thus posing limitations to the geometric diversity of resultant 3D mesostructures. To offer nonuniform strains with desired spatial distributions in the 3D assembly, this paper introduces a versatile set of concepts in the design of engineered substrates with heterogeneous integration of materials of different moduli. Such heterogeneous, deformable substrates can achieve large strain gradients and efficient strain isolation/magnification, which are difficult to realize using the previously reported strategies. Theoretical and experimental studies on the underlying mechanics offer a viable route to the design of heterogeneous, deformable substrates to yield favorable strain fields. A broad collection of 3D mesostructures and associated heterogeneous substrates is fabricated and demonstrated, including examples that resemble windmills, scorpions, and manta rays and those that have application potentials in tunable inductors and vibrational microsystems.

20.
Int J Biol Macromol ; 123: 1035-1043, 2019 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-30399378

RESUMO

Osteosarcoma is a common primary bone malignancy, and distant metastasis limited the cure estimate during last decades. Detailed investigation of osteosarcoma metastasis is valuable for improving therapeutic strategy. Our study indicated increased integrin-ß1 expression and NF-kB signaling activation in metastatic osteosarcoma tissues. Gain-of-function assays showed that integrin-ß1 knockdown significantly inhibited osteosarcoma growth and metastasis, whereas exogenous reintroducing of integrin-ß1 restored cell proliferation and metastasis in vitro and in vivo. NF-κB signaling directly modulated integrin-ß1 expression, which is an effective target for the treatment of osteosarcoma. Mechanically, integrin-ß1 blockage with AIIB2 antibody increased osteosarcoma cell apoptosis. Immunohistochemistry staining of integrin-ß1 revealed that elevated integrin-ß1 expression was correlated with poor prognosis of osteosarcoma patients and acted as an independent detrimental factor for osteosarcoma. Our data showed that integrin-ß1 and NF-κB signaling are promising therapeutic targets to improve the clinical outcome of osteosarcoma patients. The examination of integrin-ß1 expression will also identify patients with high risk of disease progression.


Assuntos
Apoptose , Integrina beta1/metabolismo , NF-kappa B/metabolismo , Osteossarcoma/metabolismo , Osteossarcoma/patologia , Transdução de Sinais , Adulto , Animais , Linhagem Celular Tumoral , Proliferação de Células , Intervalo Livre de Doença , Feminino , Humanos , Masculino , Camundongos , Análise Multivariada , Metástase Neoplásica , Prognóstico , Adulto Jovem
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