Magnetic particle imaging (MPI) is a powerful and rapidly growing tomographic imaging technique that allows for the non-invasive visualization of superparamagnetic nanoparticles (NPs) in living ...matter. Despite its potential for a wide range of applications, the intrinsic quantitative nature of MPI has not been fully exploited in biological environments. In this study, a novel NP architecture that overcomes this limitation by maintaining a virtually unchanged effective relaxation (Brownian plus Néel) even when immobilized is presented. This superparamagnetic magnetite architecture made of phenolic resin hollow spheres coated with Eu(III) containing silica nanoparticles (SMARTH RHESINs) was synthesized and studied. Magnetic particle spectroscopy (MPS) measurements confirm their suitability for potential MPI applications. Photobleaching studies show an unexpected photodynamic due to the fluorescence emission peak of the europium ion in combination with the phenol formaldehyde resin (PFR). Cell metabolic activity and proliferation behavior are not affected. Colocalization experiments reveal the distinct accumulation of SMART RHESINs near the Golgi apparatus. Overall, SMART RHESINs show superparamagnetic behavior and special luminescent properties without acute cytotoxicity, making them suitable for bimodal imaging probes for medical use like cancer diagnosis and treatment. SMART RHESINs have the potential to enable quantitative MPS and MPI measurements both in mobile and immobilized environments.
Phenol formaldehyde (PF) resin were treated with cellulose nanofibrils (CNF), and its effects on the cure kinetics of PF resin were evaluated. The curing of PF resin was a polycondensation exothermic ...reaction forming insoluble polymer. The Differential scanning calorimetry (DSC) analysis showed 3% CNF addition had prolonged the curing process of PF resin, and the Kissinger equation and Crane equation were introduced to show that the curing activate energy and reaction order of 3%-CNF-added-PF resin sample were obviously lower than control ones. The scanning probe microscopy (SPM) results exhibited that CNF particles were well-dispersed in the PF matrix. The non-isothermal kinetic study indicated that CNF had played a major role during late stage of non-isothermal polymerization, increasing the crosslinking points in the PF resin and reducing the energy needed for PF resin curing. Thus, the addition of CNF had a positive effect on the curing of PF and made the curing more perfect.
In order to clarify the effects of crude bio-oil for phenol-formaldehyde resin, the phenol-formaldehyde resin with bio-oil model compounds (BMPF) were prepared by model compound method. The bonding ...strength and aging resistance of BMPF were determined, and their microstructure and chemical bonds were also analyzed by scanning electron microscope, Fourier transform infrared spectroscopy, and nuclear magnetic resonance analysis, respectively. The results showed that the components of crude bio-oil had various degrees of effects on the BMPF performance, and the most obvious one is the phenols. The phenols and the ketones of bio-oil had positive effects on the bonding strength. The ketones had the biggest effect on the surface smoothness of BMPF film. But all components of bio-oil could inordinately improve the aging resistance of BMPF. The structural analysis indicated that the effects of bio-oil components on the BMPF performance by changing the resin structure. The CH2 peak in FT-IR and the methylene bridges intensity in NMR of phenol-free BMPF and ketone-free BMPF were smaller, while the results of aldehyde-free BMPF and acid-free BMPF were opposite. And the influence degree of BMPF structure was basically consistent with that of BMPF performance. These results could provide a basis for the modification of phenol-formaldehyde resin by crude bio-oil.
A highly‐efficient nano‐medical carrier system was constructed for drug release based on a facile synthesis, excellent fluorescence, and structure of phenol formaldehyde resin (PFR). The PFR was ...easily synthesized through a simple one‐step hydrothermal reaction, reduction and etching process, and a silane coupling agent modification process. The multiple functionalized drug delivery system, defined as PFR‐NH2@DOX was constructed by loading Adriamycin (DOX) into PFR. Drug release results in vitro displayed a DOX content of 145 mg g−1 prodrug nanosphere has excellent pH‐triggered drug release (about 84.71%) within 72 h at pH 5 solution. The fluorescence recovery of PFR after DOX release indicates the potential application in fluorescence imaging and controlled drug release.
A novel nano‐drug carrier system with high efficiency and fluorescence was constructed by functionalizing phenolic resin (PFR). Porous PFR was synthesized through the simple hydrothermal reaction, reduction and etching process, and silane coupling agent modification process. The release result in vitro showed that the potential applications of PFR in fluorescence imaging and controlled drug release.
Owing to the low cost and abundant resource of sodium, sodium-ion batteries demonstrate bright application prospects for large-scale energy storage systems. Microstructure-controlled amorphous carbon ...with proper surface area and high electronic conductivity is considered to be one of the most promising anode material. Nevertheless, the cost of the reported carbon materials is still high because of the low carbon yield and expensive precursors. Besides, the low initial coulombic efficiency is also a big challenge. Herein, a high-yielding (70%) microstructure-controlled amorphous carbon is achieved via a pre-oxidation stabilization process and following carbonization of the mixed pitch and phenol formaldehyde resin precursor. The effects of pre-oxidation stabilization on adjusting the microstructure of amorphous carbon are systematically investigated, as well as the electrochemical performance. The optimal sample exhibits high initial coulombic efficiency (82%), high reversible capacity (268.3 mAh g−1 at 0.1 C) and good rate capability (106 mAh g−1 at 4 C) as an anode material of sodium-ion batteries. This high-performance amorphous carbon material is prepared via a controllable and low-cost strategy, presenting an appealing development of practical anode materials for sodium-ion batteries.
Display omitted
•High yielding amorphous carbon is obtained via an oxidative stabilization strategy.•In-situ FTIR spectroscopy presents the interaction between the precursors.•The controlled disordered structures lead to a high initial coulombic efficiency.•The carbon shows good electrochemical properties in both half cells and full cells.
Tobacco (
L.) aroma is an important attribute of tobacco quality and is influenced by a variety of minor chemical components, including carotenoid degradation products. The objectives of this work ...were to determine the content of the most important fragrance-shaping carotenoid degradation products in the essential oils (EOs) of the three types of Bulgarian tobacco-Oriental (OR), flue-cured Virginia (FCV), and Burley (BU)-and to compare them with other aromatic products from tobacco. The content of total carotenoids and β-carotene was highest in BU tobacco (22.23 and 20.34 mg/100 g DW, respectively), followed by OR (13.60 and 12.09 mg/100 g DW in variety "Plovdiv 7" (Pd7); 6.27 and 5.45 mg/100 g DW in "Krumovgrad" (Kr), and FCV (5.93 and 3.73 mg/100 g DW). EOs were obtained by hydrodistillation in an acidified medium, and the main aroma-impact compounds from carotenoid degradation (identified by GC-MS) were as follows: FCV-α-ionone (0.61 mg/100 g DW), dihydro-β-ionone (0.96 mg/100 g DW), β-damascenone (1.26 mg/100 g DW); BU-α-ionone (0.73 mg/100 g DW), dihydro-β-ionone (1.19 mg/100 g DW), β-damascenone (1.35 mg/100 g DW); OR(Kr)-α-ionone (0.20 mg/100 g DW), β-ionone (1.08 mg/100 g DW), dihydro-β-ionone (1.34 mg/100 g DW), β-damascenone (0.36 mg/100 g DW); OR(Pd7)-α-ionone (1.43 mg/100 g DW), dihydro-β-ionone (1.73 mg/100 g DW), β-damascenone (1.23 mg/100 g DW). Ionone and its derivatives were not identified in the aroma extraction products concrete, resinoid, or absolute. The results suggest that temperature, pH of the medium, process duration, and possibly other unknown factors affect carotenoid transformation. The study provides insight into the composition of tobacco EOs and may be of interest to the fragrance industry.
The effect of dimension of carbon foam (CF) grains used as a filler of epoxy matrix on the morphology and thermomechanical and tribological properties of final composites was described. The carbon ...foam proposed as particle reinforcement of composites was prepared from epoxy resin of diglycidyl ether of bisphenol A type cured with phenol-formaldehyde resin (novolac) in a self-foaming process followed by carbonization. Structures of the carbon foam filler and resultant composites were studied by microscopic and spectroscopic methods. Three different carbon foam grain fractions, below 200 μm, 200–315 μm and below 315 μm, keeping CF porous structure and specific properties, were used to obtain new composite materials. There were observed good quality dispersion of CF grains in epoxy matrix and excellent adhesion at interfacial areas, regardless of carbon foam fraction. In the effect, these composites have enhanced thermomechanical and tribological properties and relatively low density compared to carbon-polymer composites produced so far. It was found that all CF fractions used reduced friction coefficient of resultant composites compared to pure epoxy matrix, however the influence of individual filler fraction on composite's COF was different. The morphology of worn surfaces of epoxy composites after friction tests showed that the effect depends on grain fraction of CF filler as well as on the load used.
•Carbon foam grains as reinforcement of epoxy matrix were used.•Carbon foam fraction had an effect on thermomechanical properties of composites.•Dependence of composites friction coefficients on foam grain fractions was found.•Epoxy composites with various foam fractions showed different wear characteristics.
Resole resins have many applications, especially for foam production. However, the use of phenol, a key ingredient in resoles, has serious environmental and economic disadvantages. In this work, ...lignin extracted from pine wood using a "green" solvent, levulinic acid, was used to partially replace the non-sustainable phenol. The physicochemical properties of this novel resin were compared with resins composed of different types of commercial lignins. All resins were optimized to keep their free formaldehyde content below 1 wt%, by carefully adjusting the pH of the mixture. Substitution of phenol with lignin generally increases the viscosity of the resins, which is further increased with the lignin mass fraction. The addition of lignin decreases the kinetics of gelification of the resin. The type and amount of lignin also affect the thermal stability of the resins. It was possible to obtain resins with higher thermal stability than the standard phenol-formaldehyde resins without lignin. This work provides new insights regarding the development of lignin-based resoles as a very promising sustainable alternative to petrol-based resins.
Graphene oxide was reduced (RGO) by naturally abundant potato starch and incorporated in phenol formaldehyde resin (PF). The PF/RGO nanocomposites were successfully fabricated by the combination of ...solution processing and compression molding. Here, nanocomposites composed of 0.05 wt% to 1 wt% RGO were prepared. The incorporation of RGO into the PF matrix was significantly affecting the dynamic mechanical characteristics of the nanocomposites such as storage and loss modulus and tan δ. The degree of entanglement (N), effectiveness of filler (βf), reinforcement efficiency factor (r), cross‐link density (vc), and adhesion factor (A) were evaluated from the modulus values. Besides, the phase behavior of the nanocomposites was analyzed with help of Cole–Cole plot. The electrical properties of the nanocomposites have been studied concerning change in filler loading and frequency. The dielectric constant (ε′), dielectric loss (ε″) and conductivity were increased with increase in wt% of filler for the entire range of frequencies (20 Hz to 30 MHz) and the results showed that the electrical conductivity of the nanocomposites can be explained by percolation theory. The Maxwell‐Garnet model was employed to calculate the theoretical dielectric constant of PF/RGO nanocomposites.
PDF
