Nano

Good breakdown strength is an important feature for the selection of dielectric materials, especially in high-voltage engineering. Although nanocomposites have been shown to possess many promising dielectric properties, the breakdown strength of nanocomposites is often found to be negatively affected. Recently, imposing nonisothermal crystallization processes on polyethylene blends has been demonstrated to be favorable for breakdown strength improvements of dielectric materials. In an attempt to increase nanocomposites’ voltage rating, this work reports on the effects of nonisothermal crystallization (fast, moderate and slow crystallizations) on the structure and dielectric properties of a polyethylene blend (PE) composed of 80% low density polyethylene and 20% high density polyethylene, added with silicon dioxide (SiO₂) and silicon nitride (Si₃N₄) nanofillers. Through breakdown testing, the breakdown performance of Si₃N₄-based nanocomposites was better than SiO₂-based nanocomposites. Since nanofiller dispersion within both nanocomposite systems was comparable, the enhanced breakdown performance of Si₃N₄-based nanocomposites is attributed to the surface chemistry of Si₃N₄ containing less hydroxyl groups than SiO₂. Furthermore, the breakdown strength of SiO₂-based nanocomposites and Si₃N₄-based nanocomposites improved, with the DC breakdown strength increasing by at least 12% when both the nanocomposites were subjected to moderate crystallization rather than fast and slow crystallizations. This is attributed to changes in the underlying molecular conformation of PE in addition to water-related effects. These results suggest that apart from changes in the nanofiller surface chemistry, changes in the underlying molecular conformation of polymers are also important to improve the breakdown performance of nanocomposites.

Highly-dispersed graphene nanodots (GNDs) up to 10nm are synthesized using D-galactose as a carbon precursor. The GNDs are self-passivized, emit dual-color excitation-dependent emission and highly biocompatible in cell lines. Their applicability is demonstarted for cellular bioimaging and Raman mapping of cells. Furthermore, their implications on mammalian cell growth and plant seed germination are expounded.

Herein, KH-550 was used as surface modifier to prepare modified MnO₂/reduced graphene oxide (M-MnO₂/rGO) composite electrode materials by utilizing electrostatic interaction at low temperature and normal pressure. X-ray diffraction, scanning electron microscopy, transmission electron microscopy and X-ray photoelectron spectroscopy were adopted to characterize the material’s phase, morphology, and valence state of elements. The electrochemical properties of the material were measured using a three-electrode system. The results indicate a decrease in the size of the modified MnO₂ particles, and that they were uniformly distributed on the rGO sheets. The M-MnO₂/rGO composite attained a specific capacitance of 326F$\cdot$g${}^{-1}$ in a solution of 1mol$\cdot$L${}^{-1}$ Na₂SO₄ at a current density of 0.5A$\cdot$g${}^{-1}$. The specific capacitance of the material was 92.4% after 1000 cycles. The electrostatic self-assembly method effectively solved the problem of reducing the cycling stability while improving the specific capacitance of the composite materials, and further improved the possibility of applying MnO₂/rGO in the field of supercapacitors.

The construction of organic–inorganic hybrids is one of the important ways to improve performances of photocatalysts. In this study, perylene tetracarboxylic tetra (n-butyl) ester loaded titanium dioxide (PTTE-B/TiO₂) nanocomposite was successfully synthesized by hydrothermal method. The catalyst was characterized by XRD, DRS, XPS, Photoluminescence spectroscopy (PL) and BET. FT-IR and XPS analyses revealed the presence of Ti$\dots$O bond in the interfaces between TiO₂ and PTTE-B. The photoluminescence intensity of PTTE-B/TiO₂ was decreased compared to TiO₂, which indicated a suppression of electron–hole recombination by the loaded PTTE-B nanoparticles. The photocatalytic activity of PTTE-B/TiO₂ nanocomposite for degradation of EBT using visible light was higher than that of prepared TiO₂ or TiO₂-P25. The detection of radical scavengers confirmed that h${}^{+}$ and $•{\text{O}}_2^{-}$ were the main active substances for Eriochrome Black T (EBT, an azo dye) degradation. The Ti$\dots$O bond acted as a short and fast channel for photogenerated charge carriers to migrate from PTTE-B to TiO₂. Furthermore, PTTE-B/TiO₂ was found to be stable and reusable.

In recent years, microfluidic devices present unique advantages for the development of a new generation of nanoparticle synthesis method compared to bulk methods. In this study, we report a microfluidic flow-focusing method for the production of all trans retinoic acid (ATRA)-loaded methoxy poly(ethylene glycol)-poly(lactide-coglycolide) (mPEG-PLGA) nanoparticles (NPs). Box–Behnken experimental design (BBD) was applied to optimize of formulation ingredients and process conditions with minimum particle size, maximum drug loading% (DL%) and encapsulation efficiency% (EE%). Polymer concentration, drug concentration and flow rates of solvent (S) and antisolvent (AS) were selected as independent variables. Based on optimization strategy, minimum particle size achieved shows average (SD) particle size of $159\pm 8$nm with DL of $7.1\pm 0.04$wt.% and EE of $98.71\pm 0.58$wt.%, respectively. While maximum DL has been reported to be $16.51\pm 0.03$wt.% with particle size of $205\pm 5.29$nm and EE of $99.42\pm 0.45$wt.%, respectively. Moreover, the results have shown that the AS/S ratio represents the most significant effect on particle size. Indeed, increasing the AS flow rate directly results in generating smaller particles. The AS/S ratio represents the least significant effect on DL%, such that, at fixed flow rates, higher DL was observed at high concentration of drug and lower concentration of polymer. In conclusion, optimization of the ATRA-loaded mPEG-PLGA NPs by BBD yielded in a favorable drug carrier for ATRA that could provide a new treatment modality for different malignancies.

CuO/CNT composites were synthesized via simple and rapid microwave approach. The nanocomposites were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). Further, the electrochemical performances of CuO/CNT composites were evaluated. The prepared samples displayed high specific capacitances of 164.5Fg${}^{-1}$ at 1Ag${}^{-1}$, during the cycle process, the capacitance value aggrandized to 274.7Fg${}^{-1}$, and the capacitance remained at 166% of the primary value after 10 000 turns. Moreover, the CuO/CNT//AC asymmetric supercapacitor (ASC) exhibited an energy density of 17.08Whkg${}^{-1}$ at 775Wkg${}^{-1}$ and excellent electrochemical stability in 6M KOH aqueous electrolyte, showing its enormous potential in energy-storage devices.

Synthesis and visible-light photocatalytic N₂/H₂O to ammonia at atmospheric pressure and room temperature is considered to be the most ideal ammonia synthesis technology. In this study, coal-based carbon dots (CDs) were prepared by H₂O₂ oxidation method using cheap and ubiquitous coal as the carbon source. Then the gold sol was connected to CDs to obtain a core-shell structure photocatalyst Au@CDs by sodium borohydride (NaBH₄) reduction method. While characterizing the material structure, the photocatalytic N₂/H₂O to ammonia performance of Au@CDs was investigated. The results show that the introduction of CDs in Au @CDs photocatalysts can not only improve the performance of the catalyst to excite carriers in visible light, but also inhibit the recombination of photogenerated electron-hole pairs, promote the charge transport ability and make photogenerated electrons and holes move smoothly to the catalyst surface. Meanwhile, the adsorption and dissociation capacity of N₂ on the catalyst surface can be improved, thereby the photocatalytic N₂/H₂O ammonia synthesis reaction of Au@CDs can proceed smoothly.

In this study, we have successfully synthesized porous CoO–Co@RGO composites using GO and Co-based metal-organic frameworks (MOFs) as precursors. Due to particular structures and advantageous characteristics, the synthesized porous CoO–Co@RGO composites exhibit outstanding electromagnetic (EM) wave absorbing properties with a filler loading of 10wt.% in wax matrix. The maximum reflection loss (RL) of the prepared porous CoO–Co@RGO was $-34.22$dB with 2.1mm thickness, and the effective absorption bandwidth as wide as 6.24GHz (11.76–18GHz), which covers the full Ku-band. Remarkably, the achieved all values ofRL were under $-10$dB with 1.0–5.0mm thickness, the corresponding to bandwidth range can be tuned to 13.84GHz (4.16–18GHz). The superior absorbing performance is attributed to suitable magnetic loss, high dielectric loss and large attenuation mainly caused by conduction loss and polarization relaxation.

A new fluorescence composite material for the sensitive and selective determination of 4-nitrophenol (4-NP) was developed based on molecularly imprinted polymers (MIPs) incorporated with carbon dots (CDs). First, fluorescent CDs with a high quantum yield (QY) of 51.8% were prepared by hydrothermal synthesis method by using anhydrous citric acid as carbon source and AEAPMS as surface modifier. Then, CDs were fabricated with MIPs (CDs@MIPs) by sol–gel method using 4-NP as template, (3-aminopropyl) triethoxysilane (APTES) as functional monomer, tetraethoxysilane (TEOS) as cross-linker and CDs as signal sources, respectively. The CDs@MIPs exhibited strong fluorescence property and high selectivity to 4-NP as it incorporated merits of CDs and MIPs. Under optimized conditions, the relative fluorescence intensity of CDs@MIPs decreased linearly with the concentration of 4-NP from 0.025$\mu$gmL${}^{-1}$ to 5$\mu$gmL${}^{-1}$. The limit of detection (LOD) of 4-NP was 5ngmL${}^{-1}$ (35nM). Specificity and selectivity experiments showed that CDs@MIPs can selectively detect 4-NP with rare interference of other competitive analogs and metal ions. Finally, CDs@MIPs was successfully used to detect 4-NP in river water samples with the recoveries ranging from 94.0% to 103.4%. The results demonstrated that the prepared CDs@MIPs can be applied to the selective and sensitive detection of trace 4-NP in real samples.

Biomass-based activated porous carbon (PC) with large porosity and high surface area has been considered as potential electrode material for supercapacitors. The spongy-like porous-activated carbon (SPAC) was prepared from millfeed by one-step carbonization/activation with KOH treatment. It shows three-dimensional (3D) spongy-like structure and high specific surface area (1535m²g${}^{-1}$). The SPAC electrode exhibits a high specific capacitance (237.9Fg${}^{-1}$ at a current density of 0.5Ag${}^{-1}$) and a superior cycle stability (the capacitance retention of 95% after 10000 cycles at 2Ag${}^{-1}$) in 2M KOH electrolyte, while the SPAC reveals a high specific capacitance of 157Fg${}^{-1}$ at 0.5Ag${}^{-1}$, good electrochemical stability with 93% capacitance retention after 5000 cycles in ionic liquids. Furthermore, the specific capacitance of SPAC//SPAC supercapacitor reaches 82.1Fg${}^{-1}$ at a current density of 0.5Ag${}^{-1}$ and achieves a high capacitance retention of 75% when the charging current increases to 10Ag${}^{-1}$ in 2M KOH electrolyte. The SPAC//SPAC supercapacitor possesses a high specific capacitance of 29.6Fg${}^{-1}$ at 0.5Ag${}^{-1}$ and a preeminent energy density of 27.8Whkg${}^{-1}$ (at a power density of 640Wkg${}^{-1}$) in ionic liquids. This paper provides a convenient approach to synthesize low-cost biomass-based carbon material for supercapacitor applications.

In this paper, polyaniline/FeFe(CN)₆(PANI-FeFe(CN)₆) composites were prepared by a simple in-situ oxidation polymerization in perchloric acid (HClO₄) solution in which the obtained polyaniline (PANI) self-assembled to form the tube-like morphology, while FeFe(CN)₆ with perfect face-centered cubic lattice (FCC)-type structure was well-dispersed in the obtained PANI matrix. As the cathode of lithium ion battery, PANI-FeFe(CN)₆ composite demonstrates the improved specific capacity, cycling stability and current rate performances. For PANI-FeFe(CN)₆ composite prepared by feed mass ratio of FeFe(CN)${}_{6:}$ Aniline to 80:100 (PANI-FeFe(CN)₆(80%)), it still remained 95.7mAh/g of discharge capacity after 100 cycles, indicating its excellent cycling performances. Especially, its specific capacities were 95.9, 98.8, 91.4, 83.6 and 72mAh/g at the current density of 20, 50, 100, 200 and 500mA/g, which were obviously higher than that of PANI or FeFe(CN)₆, respectively. The improved thermal stability and electrochemical performances for PANI-FeFe(CN)₆ composites could be ascribed to the formed interaction between PANI and FeFe(CN)₆ components and the enhanced electrical conductivity, which made it a potential candidate as the cathode of lithium battery.

Owing to the special structural characteristics, oxide derivatives of Prussian blue (PB)-based hollow structures are widely used in electrochemical energy storage and conversion. Here, Fe₃O₄ particles have been synthesized by one-step thermal decomposition of PB. The cube-sized iron-based PB and structural stability of thermal decomposition products at different amount of polyvinyl pyrrolidone (PVP) were well investigated. In the derivatived architecature, the hollow Fe₃O₄ nanocubes provide high-efficiency lithium ion transporation and the diffusion of electrolyte, enabling better electrochemical performance. The as-obtained Fe₃O₄ nanocubes show a remarkable rate capability (462mAhg${}^{-1}$ at 1.0A/g) and outstanding specific capacity (803mAhg${}^{-1}$ at 0.1A/g, 97.5% capacity retention over 140 cycles), which have a potential application as anode materials for lithium ion batteries due to the facile preparation method and high electrochemical performance.

In this work, organophilic carbon nanodots (CNDs) were synthesized in acetone from organic extract of plant leaves. The as-prepared CNDs showed multi-band emission, and could be well dispersed in acetone and ethanol. The photoluminescence (PL) of the CNDs at 520nm was excitation-independent. The PL in the blue region could be tuned from 420 to 480nm through changing of the excitation wavelength. The multi-emissive CNDs were used as a ratiometric and colorimetric sensor for curcumin detection in ethanol. The blue PL of the CNDs at 420nm was quenched by curcumin through inner filter effect. Meanwhile, the green PL at 495nm and 535nm were enhanced with additional fluorescence of curcumin. The value of I${}_{535}$/I${}_{420}$ and I${}_{495}$/I${}_{420}$ both increased linearly with the curcumin concentration in the range of 0–15$\mu$M. The fluorescence color of the mixed solution changed from blue to yellow, and the detection limit reached 36.7nM. The sensitive and visual detection of the CNDs probe toward curcumin showed their high potential in practical applications.

Nucleic acid detection is becoming increasingly important in the diagnostics of genetic diseases for biological analysis. We herein propose gold nanoparticles as probe for colorimetric detection of nucleic acids with branched DNA nanostructures, which enables a novel and simple colorimetric biosensor. In our system, the target DNA specifically triggered two short-chain ssDNA probes to generate branched DNA nanostructures (Y-shape DNA), which prevent AuNPs from aggregation in aqueous NaCl solution. On the contrary, when the target DNA did not exist, gold nanoparticles were unstable and aggregated easily because there is no anti-aggregation function from Y-shape DNA. Sensor response was found to be proportional to the target DNA concentration from 5 to 100nM, with detection limits determined as 5nM. The developed platform is for colorimetric nucleic acid detection without enzymes, label and modification holds great promise for practical applications.