The antioxidant activities of buckwheat (
Fagopyrum esculentum Möench) extracts were evaluated and compared with butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT) and tertiary ...butylhydroquinone (TBHQ) using a β-carotene bleaching assay, a 2,2-diphenyl-β-picrylhydrazyl (DPPH) assay and the Rancimat method. Buckwheat was extracted with solvents of different polarities. The methanol extract showed the highest antioxidant activity coefficient (AAC) of 627
±
40.0 at 200 mg/l by the β-carotene bleaching method and longest induction time of 7.0
±
0.2 h by the Rancimat method. The acetone extract showed the highest total phenolics of 3.4
±
0.1 g catechin equivalents/100 g and the highest scavenging activity of 78.6
±
6.2% at 0.1 mg/ml by the DPPH method. The properties of the extracting solvents significantly affected the yield, total phenolics and antioxidant activity of buckwheat extract.
Vasculogenic mimicry (VM) refers to the unique capability of aggressive tumor cells to mimic the pattern of embryonic vasculogenic networks. In the study we demonstrated that CD133 expression was the ...highest in triple-negative (TN) breast cancer specimens. Importantly, VM showed statistical correlation with CD133(+) expression. The presence of the close relationship between VM and CD133(+) expression might be central for TN tumor relapse and progression. The TN breast cancer cell line, MDA-MB-231 cells developed a range of colony morphologies paralleling the holoclone, meroclone and paraclone morphologies produced by normal keratinocytes and other epithelial cancer cell lines when plated at clonal densities. Holoclone cells were capable of forming more colonies on soft agar than meroclone cells and paraclone cells, suggesting that holoclone cells had higher self-renew potential and might harbors cancer stem cells (CSCs) subpopulation. Strikingly, it was holoclone that displayed CD133(+) phenotype and formed VM. In addition, holoclone acquired endothelial cell marker vascular endothelial-cadherin expression and upregulated VM mediators matrix metalloproteinase (MMP)-2 and MMP-9 expression. The subpopulation with holoclone morphology, CD133(+) phenotype and CSCs characteristics might have the capacity of transdifferentiation and contributed to VM in TN breast cancer. The related molecular pathways may be used as novel therapeutic targets for the inhibition of angiogenesis and metastasis in TN breast carcinoma.
In this work, a comprehensive model is established to predict the surface roughness achieved by single point diamond turning. In addition to the calculation of the roughness components in relation to ...the kinematics and minimum undeformed chip thickness, the newly developed model also takes the effects of plastic side flow and elastic recovery of materials as machined into account. Moreover, the ‘size effect’ has also been successfully integrated into the model, i.e. an inflection point appears in the trend line of predicted surface roughness as the ratio of maximal undeformed chip thickness to cutting edge radius (hDmax/rn) is equal to one unit. Face turning experiments validate that the maximal prediction error is only 13.35%. As the ratio of hDmax/rn is higher than one unit, both the prediction and experiments reveal that a conservation law exists in diamond turned surface roughness, owing to the competitive effects of kinematics, minimum undeformed chip thickness, plastic side flow and elastic recovery of materials on surface formation. Under the conservation law, the freedom control for an invariable surface roughness can be fulfilled in response to a quantitative ratio of hDmax/rn, either through an accurate configuration of feed rate and depth of cut with fixed tool nose radius and cutting edge radius, or by a reasonable selection of tool nose radius and controlled cutting edge radius with designed feed rate and depth of cut.
•A comprehensive model is established to calculate diamond turned surface roughness.•The ‘size effect’ is successfully taken into account in the model.•A conservation law is firstly found in diamond turned surface roughness.•Accurate configuration of tool geometries or process parameters conserves surface roughness.
Recombinant adeno-associated virus (rAAV) has shown great promise as a potential cure for neurodegenerative diseases. The existence of the blood-brain barrier (BBB), however, hinders efficient ...delivery of the viral vectors. Direct infusion through craniotomy is the most commonly used approach to achieve rAAV delivery, which carries increased risks of infection and other complications. Here, we report a focused ultrasound (FUS)-facilitated noninvasive rAAV delivery paradigm that is capable of producing targeted and neuron-specific transductions. Oscillating ultrasound contrast agents (microbubbles), driven by FUS waves, temporarily 'unlock' the BBB, allowing the systemically administrated rAAVs to enter the brain parenchyma, while maintaining their bioactivity and selectivity. Taking the advantage of the neuron-specific promoter synapsin, rAAV gene expression was triggered almost exclusively (95%) in neurons of the targeted caudate-putamen region. Both behavioral assessment and histological examination revealed no significant long-term adverse effects (in the brain and several other critical organs) for this combined treatment paradigm. Results from this study demonstrated the feasibility and safety for the noninvasive, targeted rAAV delivery, which might have open a new avenue in gene therapy in both preclinical and clinical settings.
•We consider two social-ecological models with the same ecological part.•We represent the social part using either the replicator or a best-response dynamics.•The two models’ equilibria differ in ...number and in stability.•The two models become more similar to each other when agents behave more rationally.•The replicator dynamics tends to allow for make-or-break dynamics.
Social-ecological models are often used to investigate the mutual interactions between an ecological system and human behaviour at a collective level. The social system is widely represented either by the replicator dynamics or by the best-response dynamics. We investigate the consequences of choosing one or the other with the example of a social-ecological model for eutrophication in shallow lakes, where the anthropogenic discharge of pollutants into the water is determined by a behavioural model using the replicator or a best-response dynamics. We discuss a fundamental difference between the replicator dynamics and the logit formulation of the best-response dynamics. This fundamental difference results in a different number of equilibria. We show that the replicator equation is a limit case of the best-response model, when agents are assumed to behave with infinite rationality. If agents act less rationally in the model using the best-response dynamics, the correspondence with the model using the replicator dynamics decreases. Finally, we show that sustained oscillations observed in both cases may differ substantially. The replicator dynamics makes the amplitude of the limit cycle become larger and makes the system come closer to full cooperation or full defection. Thus, the dynamics along the limit cycle imply a different risk for the system to be pushed by a perturbation into a desirable or an undesirable outcome depending on the socioeconomic dynamics assumed in the model. When analyzing social-ecological models, the choice of a socioeconomic dynamics is often little justified but our results show that it may have dramatic impacts on the coupled human-environment system.
Although the long‐term geomorphic evolution of an estuarine tidal flat consequent to flow alteration and erosion has been widely documented, the short‐term ecological responses of such ecosystems to ...multiple stressors remain poorly understood. We combined a mechanism‐based ecomorphodynamic model with a hydrodynamic and sediment numerical model to examine the ecological response of an estuarine tidal flat ecosystem to different magnitudes of flow discharge and erosion conditions in the Yellow River Estuary (YRE) of China. The ecological benefits of flow discharge and erosion are reported in terms of the state of the tidal flat system: (1) a patterned state with high primary production and strong sediment stabilization; and (2) a homogeneous state with low primary production and severe erosion. We focused on the nonlinear flow‐ecology relationship and identified the minimum threshold of flow discharge at which a patterned state occurs. Both flow discharge and erosion rates were shown to be important determinants of the state of the estuarine tidal flat ecosystem. We showed that a change in flow discharge altered the sediment deposition rate Sin and induced a state transition of the tidal flat ecosystem. Erosion increased the minimum threshold value of flow discharge at which a patterned state occurred. Our model framework provides an insightful method with a strong mechanistic basis to determine thresholds of flow discharge at which ecological benefits change dramatically, thereby providing a tool to make decisions regarding flow allocation in estuarine tidal flat ecosystems that are suffering from degradation caused by restricted flow and sediment load.
Key Points
A change in flow discharge alters the sediment deposition rate and induces a state transition of the estuarine tidal flat ecosystem
Erosion increases the threshold value of flow discharge at which a patterned state occurs
Our model provides an insightful method with a strong mechanistic basis to assess environmental flow in estuarine tidal flats ecosystems
The effect of the particle size on the mechanical properties of polymeric composites reinforced with spherical particles was investigated. The size of particles varied from macro (0.5
mm) to nano (15
...nm) scale. It was found that particle sizes at micro scale have little influence on the Young’s modulus of the composite and that Young’s modulus increases as the size of particles decreases at nano scale. It was also observed that tensile strength of the composite is significantly dependent on particle size. At 1
vol% loading, the tensile strength increased as the particle size decreased. However, the trend for the composite with alumina nanoparticles of 3% volume fraction was found to be opposite. TEM and SEM micrographs showed higher likelihood of poor dispersions in the composite with 3
vol% nanoparticles than that with 1
vol%. To understand the effect of the particle size in micron scale on the failure process, finite element analyses showed that total strain energy release rate for particle/matrix debonding growth decreases as particle size decreases and that sliding fracture mode becomes dominant as the debonding grows. It was found that interfacial fracture toughness does not depend on particle size but increases substantially when the sliding fracture mode prevails.
The effect of shoulder coupling in friction stir welding (FSW) on the distribution of residual stresses, microstructure and hardness has been investigated by comparing welds manufactured with a ...conventional tool, using different levels of downforce, to joints produced using a stationary shoulder (SSFSW). The welds were produced in AA7050-T7651 6.35 mm plate with the same travel speed and similar power levels. Reducing the tool downforce in FSW led to a decrease in the overall shoulder input power, but a minimal reduction in the weld zone hardness and peak residual stresses. In contrast, relative to FSWs made with a similar input power, the stationary shoulder led to much more significant microstructure and property changes including a reduction in the HAZ width, an increase in the minimum weld zone hardness level and a significant reduction in the peak tensile residual stresses (by ~ 25%). With SSFSW, the improvement found in the hardness and residual stress distribution from eliminating the energy dissipated by the tool shoulder could be directly correlated to a reduction in the weld temperature and narrowing of the thermal field, which reduced the size of the HAZ and region of plastic misfit responsible for the weld residual stresses. By comparing the results with previous work it was found that, apart from using a stationary shoulder, the most important welding parameter affecting the weld zone peak tensile stresses was the travel speed, with longitudinal residual stresses doubling upon increasing the travel speed from 100 to 400 mm/min.
Hormone-sensitive prostate cancer typically progresses to castration resistant prostate cancer (CRPC) after the androgen deprivation therapy. We investigated the impact of microRNAs (miRs) in the ...transition of prostate cancer to CRPC. MiR-221/-222 was highly expressed in bone metastatic CRPC tumor specimens. We previously demonstrated that transient overexpression of miR-221/-222 in LNCaP promoted the development of the CRPC phenotype. In current study, we show that stably overexpressing miR-221 confers androgen independent (AI) cell growth in LNCaP by rescuing LNCaP cells from growth arrest at G1 phase due to the lack of androgen. Overexpressing of miR-221 in LNCaP reduced the transcription of a subgroup of androgen-responsive genes without affecting the androgen receptor (AR) or AR-androgen integrity. By performing systematic biochemical and bioinformatical analyses, we identified two miR-221 targets, HECTD2 and RAB1A, which could mediate the development of CRPC phenotype in multiple prostate cancer cell lines. Downregulation of HECTD2 significantly affected the androgen-induced and AR-mediated transcription, and downregulation of HECTD2 or RAB1A enhances AI cell growth. As a result of the elevated expression of miR-221, expression of many cell cycle genes was altered and pathways promoting epithelial to mesenchymal transition/tumor metastasis were activated. We hypothesize that a major biological consequence of upregulation of miR-221 is reprogramming of AR signaling, which in turn may mediate the transition to the CRPC phenotype.
A technique was developed to improve the strength of unidirectional composites by enhancing the matrix properties through nanoparticles infusion. A commercially available standard DGEBA epoxy with ...silica nanoparticles (Nanopox F 400) was used as the matrix to make fiber composites. The silica nanoparticles in Nanopox were grown in situ via a sol–gel process resulting in a concentration of 40
wt% which was later diluted to 15
wt% particle loading. TEM images showed very uniform dispersion of silica nanoparticles with a size distribution of about 20
nm. Compression test revealed a substantial improvement (40%) in elastic modulus of the modified epoxy. A modified vacuum assisted resin transfer molding process was used to fabricate unidirectional E-glass fiber reinforced silica/epoxy nanocomposites. Inclusion of silica nanoparticles dramatically increased the longitudinal compressive strength and moderately increased the longitudinal and transverse tensile strengths. A microbuckling model was used to verify the compression testing results.
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