Deep tumor penetration,
long blood circulation, rapid drug release,
and sufficient stability are the most concerning dilemmas of nano-drug-delivery
systems for efficient chemotherapy. Herein, we develop reduction/oxidation-responsive
hierarchical nanoparticles co-encapsulating paclitaxel (PTX) and pH-stimulated
hyaluronidase (pSH) to surmount the sequential biological barriers
for precise cancer therapy. Poly(ethylene glycol) diamine (PEG-dia)
is applied to collaboratively cross-link the shell of nanoparticles
self-assembled by a hyaluronic acid–stearic acid conjugate
linked via a disulfide bond (HA–SS–SA,
HSS) to fabricate the hierarchical nanoparticles (PHSS). The PTX and
pSH coloaded hierarchical nanoparticles (PTX/pSH-PHSS) enhance the
stability in normal physiological conditions and accelerate drug release
at tumorous pH, and highly reductive or oxidative environments. Functionalized
with PEG and HA, the hierarchical nanoparticles preferentially prolong
the circulation time, accumulate at the tumor site, and enter MDA-MB-231
cells via CD44-mediated endocytosis. Within the acidic
tumor micro-environment, pSH would be partially reactivated to decompose
the dense tumor extracellular matrix for deep tumor penetration. Interestingly,
PTX/pSH-PHSS could be degraded apace by the completely activated pSH
within endo/lysosomes and the intracellular redox micro-environment
to facilitate drug release to produce the highest tumor inhibition
(93.71%) in breast cancer models.
Excellent mechanical properties are indispensable for the wide application of supercapacitors and various wearable devices. In this article, a novel double‐crosslinked hydrogel electrolyte (DC‐GPE) is prepared by the combination of the hydrophobic association of acrylamide with the amphiphilic monomer AEO‐9‐AC and the ionic complexation of acrylic acid with Fe3+ for the first time by a two‐step method. Owing to the dual energy dissipation network, the DC‐GPE exhibits an excellent tensile strength of up to 3.1 MPa, an elongation at break of more than 900 % and a toughness of 18.1 MJ m−3, which is far beyond the currently reported hydrogel electrolyte. Moreover, the ionic conductivity of the DC‐GPE achieves as high as 40.1 mS cm−1, which is 3 times higher than the corresponding LiClO4 solution electrolyte (12.3 mS cm−1). Besides, the activated carbon‐based supercapacitor assembled by the DC‐GPE shows excellent electrochemical performance, which is superior to most activated carbon‐based supercapacitors. These results demonstrate that the DC‐GPE shows a great application prospect in wearable devices like supercapacitors. Significantly, the new dual physical cross‐linking strategy improves the contradiction between the strength and the toughness of the gel electrolyte materials. And provides a new solution for preparing high‐strength as well as high‐toughness gel electrolyte.
Fatigue damage is one of the main reasons of the failure of Semi-Submersible platform. As the complex of random loading, it is difficult to analyze fatigue life accurately and determine the sensitivity of parameters. In this paper, the fatigue life on key-components of semi-submersible platform is analyzed with Spectral-based analysis method. Firstly, the stress responses of whole model platform under the random wave loads are calculated. The calculation results of whole model platform for cut-boundary interpolation are used in local model to calculate the key-component stress responses of local model. Generating the fatigue stress energy spectrum by scaling the wave energy spectrum and the complex fatigue stress transfer function in detail local model is described next. The stress response of short-term sea-state is assumed to obey Rayleigh distribution, and the spectral moments are calculated. Finally, the fatigue life of key components is analyzed according to S-N curve and Palmgren-Miner’s rule. The results show that the fatigue life of the connection meets the specification requirements, and the key components are the fatigue sensitive areas of semi-submersible platform.
In order to investigate the internal curing effect of recycled brick aggregate (RBA) in recycled aggregate concrete (RAC) and calculate its contribution to the final compressive strength, two RAC groups with different recycled aggregates and 6 replacement ratios (r) under 4 curing ages were tested. Results show that the compressive strengths of RACI and RACII decrease steadily with the increase of r when below 40%, and that there is a significant drop once the r is higher than 60%. The internal curing effect for RAC with a low RBA ratio is mainly reflected during the curing age of 14–21 days, while for RAC with a high RBA ratio, this internal curing effect appears earlier, during 7–14 days, and becomes very obvious after 14 days. In addition, the actual tested compressive strength of RAC replaced by 100% RBA exceeds around 40% of the expected compressive strength at the age of 28 days. When the age of RAC entirely with RBA is 28 days, the compressive strength caused by the internal curing effect accounts for around 28% of the actual tested compressive strength. The most appropriate r of RBA for RAC production is between 40% to 60%. Finally, the equations for calculating the compressive strength of RAC are presented considering the curing ages, the replacement ratios and the internal curing effect of RBA. Further, a unified equation is suggested for convenience in calculation.
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