A covalently assembled dopamine nanoparticle is constructed to serve as an intrinsic photosensitizer and pH-responsive drug nanocarrier for combined PDT and chemotherapy.
Cigarette butts, one of the most ubiquitous forms of garbage in the world, need to be recycled because their toxicity can kill saltwater and freshwater fish. In this study, the cigarette butts are applied as corrosion inhibitors for N80 steel at 90 °C in hydrochloric acid. Weight loss and electrochemical techniques are used to evaluate the corrosion inhibitive effect of cigarette butt water extracts. Results show that the inhibition efficiencies arrive at 94.6% and 91.7% in 10% and 15% (wt %) HCl solution, respectively, by adding 5% (wt %) inhibitor. In 20% HCl solution, they show a maximum inhibition efficiency of 88.4% by adding 10% inhibitor.
Sweet orange (Citrus sinensis) peel, one of the most underutilized biowaste, was in this study employed for the green synthesis of gold nanoparticles (AuNPs) as an alternative source of reductant and stabilizer. Spherical AuNPs with narrow size distribution (1.75 ± 0.86 nm) were obtained by controlling pH and adjusting sequence for the first time. ultraviolet-visible (UV-vis) spectrophotometer, transmission electron microscopy (TEM), energy-dispersive spectroscopy (EDS), dynamic light scattering (DLS) were applied to detect the characteristic surface plasmon resonance peak, morphological and aggregate characteristic, elementary composition and hydrodynamic diameter, respectively. The major functional groups in extract were tested by Fourier transform infrared(FT-IR) spectrophotometer to characterize the components which are responsible for the reduction and stabilization of AuNPs. The possible role of the components during the process of AuNPs synthesis is also discussed. The result of this study enriched the green source for ultra-small AuNPs synthesis, and will help to understand the mechanism of synthesis and stability of ultra-small AuNPs by fruit peels extract.
Lightweight structures are often used for applications requiring higher strength-to-weight ratios and lower densities, such as in aircraft, vehicles, and various engine components. Three-dimensional (3D) printing technology has been widely used for lightweight polymer structures because of the superior flexibility, personalized design, and ease of operation offered by it. However, synthesis of lightweight polymeric structures that possess both high specific strength and glass transfer temperature (T g ) remains an elusive goal, because 3D printed polymers with these properties are still very few in the market. For example, 3,3′,4,4'-biphenyl tetracarboxylic dianhydride (BPDA) and p-phenylenediamine (PDA)-type (UPILEX-S type) polyimides show exceptional thermal stability (T g up to ≈400 °C) and mechanical properties (tensile strength exceeding 500 MPa) and are the first choice if extremely high temperatures of 400 °C or even higher (depending on the duration) are required, which hampers their processing using existing 3D printing techniques. However, their processing using existing 3D printing techniques is hampered due to their thermal resistance. Herein, a 3D printing approach was demonstrated for generating complex lightweight BPDA-PDA polyimide geometries with unprecedented specific strength and thermal resistance. The simple aqueous polymerization reaction of BPDA with water-soluble PDA and triethylamine (TEA) afforded the poly(amic acid) ammonium salt (PAAS) hydrogels. These PAAS solutions showed clear shear thinning and thermo-reversibility, along with high G′ gel-state moduli, which ensured selfsupporting features and shape fidelity in the gel state. Postprinting thermal treatment transformed the PAAS precursor to BPDA− PDA polyimide (UPILEX-S type). The resulting layer-by-layer deposition onto lightweight polyimide honeycombs in the form of triangular, square, and hexagonal structures showed tailorable mechanical strength, exceptional compressive strength-to-weight ratio (highest up to 0.127 MPa (kg m −3 ) −1 ), and remarkable thermoresistance (T g approximately 380 °C). These high-performance 3D printed polyimide honeycombs and unique synthetic techniques with general structures are potentially useful in fields ranging from automotive to aerospace technologies.
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