One-Dimensional ZnO/Gold Junction for Simultaneous and Versatile Multisensing Measurements

Temperature Control of Yellow Photoluminescence from SiO2-Coated ZnO Nanocrystals

In this study, we aimed to elucidate the effects of temperature on the photoluminescence from ZnO-SiO₂ nanocomposite and to describe the preparation of SiO₂-coated ZnO nanocrystals using a chemical precipitation method, as confirmed by Fourier transform infrared (FTIR) and powder X-ray diffraction analysis (XRD) techniques. Analyses using high-resolution transmission microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX), dynamic light scattering (DLS), and electrophoretic light scattering (ELS) techniques showed that the new nanocomposite has an average size of 70 nm and 90% silica. Diffuse reflectance spectroscopy (DRS), photoluminescence (PL), and photoluminescence-excitation (PLE) measurements at different temperatures revealed two emission bands at 385 and 590 nm when the nanomaterials were excited at 325 nm. The UV and yellow emission bands were attributed to the radiative recombination and surface defects. The variable-temperature, time-resolved photoluminescence (VT-TRPL) measurements in the presence of SiO₂ revealed the increase in the exciton lifetime values and the interplay of the thermally induced nonradiative recombination transfer of the excited-state population of the yellow emission via deep centers (DC). The results pave the way for more applications in photocatalysis and biomedical technology.

Electric-Circuit Realization of Fast Quantum Search

Quantum search algorithm, which can search an unsorted database quadratically faster than any known classical algorithms, has become one of the most impressive showcases of quantum computation. It has been implemented using various quantum schemes. Here, we demonstrate both theoretically and experimentally that such a fast search algorithm can also be realized using classical electric circuits. The classical circuit networks to perform such a fast search have been designed. It has been shown that the evolution of electric signals in the circuit networks is analogies of quantum particles randomly walking on graphs described by quantum theory. The searching efficiencies in our designed classical circuits are the same to the quantum schemes. Because classical circuit networks possess good scalability and stability, the present scheme is expected to avoid some problems faced by the quantum schemes. Thus, our findings are advantageous for information processing in the era of big data.

Nanomaterials to Fight Cancer: An Overview on Their Multifunctional Exploitability

In recent years the worldwide research community has highlighted innumerable benefits of nanomaterials in cancer detection and therapy. Nevertheless, the development of cancer nanomedicines and other bionanotechnology requires a huge amount of considerations about the interactions of nanomaterials and biological systems, since long-term effects are not yet fully known. Open issues remain the determination of the nanoparticles distributions patterns and the internalization rate into the tumor while avoiding their accumulation in internal organs or other healthy tissues. The purpose of this work is to provide a standard overview of the most recent advances in nanomaterials to fight cancer and to collect trends and future directions to follow according to some critical aspects still present in this field. Complementary to the very recent review of Wolfram and Ferrari which discusses and classifies successful clinically-approved cancer nanodrugs as well as promising candidates in the pipeline, this work embraces part of their proposed classification system based on the exploitation of multifunctionality and extends the review to peer-reviewed journal articles published in the last 3 years identified through international databases.

Macroscale Superlubricity Achieved on the Hydrophobic Graphene Coating with Glycerol

Introduction of graphene-family nanoflakes in liquid results in a reduction in friction and enhanced wear resistance. However, the high demand for dispersity and stability of the nanoflakes in liquid largely restricted the choice of graphene-family nanoflakes thus far. This study proposed a new strategy to overcome this limitation, involving the formation of a graphene coating with deposited graphene-family nanoflakes, followed by the lubrication of the coating with glycerol solution. Pristine graphene (PG), fluorinated graphene (FG), and graphene oxide (GO) nanoflakes were chosen to be deposited on the respective SiO₂ substrates to form graphene coatings, and then an aqueous solution of glycerol was used as lubricant. The coefficient of friction (COF) and wear rate were reduced for all deposited coatings. However, the PG coating exhibited better lubrication and antiwear performance than FG and GO coatings. A robust superlubricity with COF of approximately 0.004 can be achieved by combining glycerol with the PG coating. The superlubricity mechanism was attributed to the formation of a tribofilm, mainly composed of graphene nanoflakes in the contact zone. The extremely low friction achieved on the hydrophobic graphene coating with liquid can aid in the development of a high-performing new lubrication system for industrial applications.

Experimental study on the kinetic effect of N-butyl-N-methylpyrrolidinium tetrafluoroborate and poly(N-vinyl-caprolactam) on CH4 hydrate formation

In this work, a series of experiments were carried out to study the kinetic inhibition performance of N-butyl-N-methylpyrrolidinium tetrafluoroborate ([BMP][BF₄]), poly(N-vinylcaprolactam) (PVCap) and compound inhibitor systems on methane hydrate from both macroscopic and microscopic perspectives. In the macroscopic experiments, the influence of the concentration, the ratio of inhibitors, the subcooling on the induction time and gas consumption rate of methane hydrate were studied. The results indicated that [BMP][BF₄] could inhibit the growth rate of CH₄ hydrate, but failed to delay the nucleation. An improved inhibitory effect was observed by combining [BMP][BF₄] and PVCap, and the optimal ratio of the two inhibitors was obtained to gain the best inhibition performance. Furthermore, the microstructure and morphology of methane hydrate crystals formed in different inhibitor systems were investigated through powder X-ray diffraction (PXRD), Raman spectroscopy and scanning electron cryomicroscopy (Cryo-SEM) methods. It was found that [BMP][BF₄] and PVCap had different influences on the large cage occupancy by CH₄ and the morphology of methane hydrate.

Synthesis, Characterization and Photocatalytic Activity of N-doped Cu2O/ZnO Nanocomposite on Degradation of Methyl Red

In this study, a N-doped Cu2O/ZnO nanocomposite was prepared by a co-precipitation and thermal decomposition technique from CuCl2, 2H2O, ZnSO4, 7H2O and CO(NH2)2 as precursors. The as-synthesized nanocomposites were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared analysis (FT–IR) and an ultraviolet–visible (UV–Vis) reflectance spectrometer. From the XRD diffractogram of N-doped Cu2O/ZnO nanocomposite, cubic and hexagonal wurtzite crystal structures of Cu2O, and ZnO, respectively were identified. The UV-vis reflectance spectra illustrated that the absorption edge of N-doped Cu2O/ZnO nanocomposite is more extended to the longer wavelength than ZnO, Cu2O and Cu2O/ZnO nanomaterials. FT–IR bands confirmed the presence of ZnO, Cu2O, and nitrogen in the N-doped Cu2O/ZnO nanocomposite. Photocatalytic activity of the as-synthesized nanocomposite was tested for methyl red degradation using sunlight as an energy source by optimizing the concentration of the dye and amount of the catalyst loaded. The degradation efficiency was greater in N-doped Cu2O/ZnO nanocomposite as compared to ZnO, Cu2O and Cu2O/ZnO nanomaterials. This is due to the coupling of the semiconductors which increases the absorption and exploitation capability of solar light and increases the charge separation as well. Besides that, nitrogen doping can extend absorption of light to the visible region by decreasing the energy gap. Therefore, N-doped Cu2O/ZnO nanocomposite is a solar light-active photocatalyst which can be used in the degradation of organic pollutants.

Urea assisted ceria nanocubes for efficient removal of malachite green organic dye from aqueous system

This study describes a simple, high-yield, rapid, and inexpensive route for the synthesis of cubic shape-like cerium oxide nanocubes (CeO₂ NCs) using different urea concentrations (0.5, 1.0, and 2.0 g) by the hydrothermal method. The synthesized nanocubes (NCs) are labeled as CeO₂ NCs-0.5, CeO₂ NCs-1.0, and CeO₂ NCs-2.0, corresponding to 0.5, 1.0, and 2.0 g of urea, respectively. The synthesized NCs were characterized by FT-IR, UV-visible, XRD, XPS, SEM and HR-TEM analysis. The synthesized NCs were cubic in shape with average sizes of 12, 12, and 13 nm for the CeO₂ NCs-0.5, CeO₂ NCs-1.0, and CeO₂ NCs-2.0, respectively, obtained by the XRD analysis. The catalytic activity of the CeO₂ NCs was studied for the purpose of obtaining the reduction of malachite green (MG) in the presence of sodium borohydride (NaBH₄) at room temperature.

Experimental Analysis of the Influence of Factors Acting on the Layer Thickness Formed by Anodic Oxidation of Aluminium

The current practice in the field of anodic oxidation of aluminium and its alloys is based mainly on a set of partial empirical experiences of technologists obtained during surface treatment. The aim of the presented paper is deeper and more complex identification of the influence of chemical and technological factors acting during the anodic oxidation process especially on the thickness of the formed surface layer by the electrolysis method in a sulfuric acid solution. The current density was selected as the basic criterion for verification evaluation and analysis of experimentally obtained data, in accordance with Faraday’s laws. For current densities of 1 to 5 A·dm−2, the synergy of significant influence factors was identified, and mathematical and statistical models were then developed to predict the thickness of the surface layer with a relative accuracy of up to 10%. The presented paper does not only focus on the observation of the thickness of the surface layer desired by the customer, but also on the monitoring of this thickness in relation to the overall layer thickness of the coating.

Two-dimensional polyimide heterojunctions for the efficient removal of environmental pollutants under visible-light irradiation

Synergism of enhanced light absorption and well intimate interfacial charge transition providing excellent photocatalytic performance of polymide heterojunctions PI–TD_x.

Zinc oxide nanocrystals as a nanoantibiotic and osteoinductive agent

In this paper we aim to analyse the behaviour of ZnO nanocrystals (ZnO NCs), prepared with a new synthetic approach and not embedded in any composite matrix, for bone implant applications in vitro. In particular, we have developed a novel, fast and reproducible microwave-assisted synthesis, to obtain highly-crystalline, round-shaped ZnO NCs of 20 nm in diameter as an extremely-stable colloidal solution in ethanol. The nanocrystals were also partially chemically functionalized by anchoring amino-propyl groups to the ZnO surface (ZnO–NH₂ NCs). Thus, the role of both ZnO NC concentration and surface chemistry were tested in terms of biocompatibility towards pre-osteoblast cells, promotion of cell proliferation and differentiation, and also in terms of antimicrobial activity against Gram positive and negative bacteria, such as Escherichia coli and Staphylococcus aureus, respectively. The results suggest that ZnO–NH₂ NCs is the most promising candidate to solve infectious disease in bone implants and at the same time promote bone tissue proliferation, even at high concentrations. Although further investigations are needed to clarify the mechanism underlying the inhibition of biofilm formation and to investigate the role of the ZnO–NH₂ NCs in in vivo assays, we demonstrated that fine and reproducible control over the chemical and structural parameters in ZnO nanomaterials can open up new horizons in the use of functionalized ZnO NCs as a highly biocompatible and osteoinductive nanoantibiotic agent for bone tissue engineering.

Nanomaterials for bone tissue engineering are developing to new solutions against infections, antibiotic resistance, promotion of new bone. ZnO nanocrystals are promising candidates with intrinsic antimicrobial activity and high biocompatibility.

Porous ZnO/2–Hydroxyethyl Methacrylate Eluting Coatings for Ureteral Stent Applications

High-surface-area porous coatings represent an interesting option to fabricate eluting stents with additional functionalities, as controlled drug delivery and antibacterial resistance properties. ZnO is a biocompatible material available in various high-surface-area morphologies, with promising antibacterial properties. Hydrophilic 2-hydroxyethyl methacrylate (HEMA) polymers (pHEMA) have been widely investigated for their biomedical applications, thanks to their biocompatibility, absence of toxicity, and tunable swelling properties. This work aims to demonstrate the use of porous ZnO/polymer bilayer coatings for future drug eluting stent applications. Sputtered mesoporous ZnO layers were coated with pHEMA and p(HEMA-co-acrylic acid (AA)) films through vacuum infiltration and drop-casting methods. The last approach was found to be the most suitable one for achieving a good polymer infiltration within the ZnO matrix and to avoid the mechanical detachment of the porous film from the substrate. The corresponding release properties were evaluated by loading a fluorescent dye in the host ZnO matrix, before drop-casting the polymer coating. For pure ZnO, the release of the dye was completed after 2 h. For ZnO/pHEMA, the sustained release of the molecule was achieved with only 30% released after 2 h and 100% released after seven days. In this case, the pH-triggered delivery properties were also demonstrated by switching from neutral to acidic pH conditions. No significant changes were obtained for the ZnO/p(HEMA-co-AA) system, which exhibited a faster swelling behavior and a release profile similar to pure ZnO.

Combined Structural, Chemometric, and Electrochemical Investigation of Vertically Aligned TiO2 Nanotubes for Na-ion Batteries

In the challenging scenario of anode materials for sodium-ion batteries, TiO₂ nanotubes could represent a winning choice in terms of cost, scalability of the preparation procedure, and long-term stability upon reversible operation in electrochemical cells. In this work, a detailed physicochemical, computational, and electrochemical characterization is carried out on TiO₂ nanotubes synthesized by varying growth time and heat treatment, viz. the two most significant experimental parameters during preparation. A chemometric approach is proposed to obtain a concrete and solid multivariate analysis of sodium battery electrode materials. Such a statistical approach, combined with prolonged galvanostatic cycling and density functional theory analysis, allows identifying anatase at high growth time as the TiO₂ polymorph of choice as an anode material, thus creating a benchmark for sodium-ion batteries, which currently took the center stage of the research in the field of energy storage systems from renewables.

Gentamicin-Releasing Mesoporous ZnO Structures

Among metal oxides, zinc oxide (ZnO) is one of the most attractive materials thanks to its biocompatible and biodegradable properties along with the existence of various morphologies featuring piezoelectric, semiconducting and photocatalytic activities. All of these structures were successfully prepared and tested for numerous applications, including optoelectronics, sensors and biomedical ones. In the last case, biocompatible ZnO nanomaterials positively influenced cells growth and tissue regeneration as well, promoting wound healing and new bone formation. Despite showing high surface areas, ZnO morphologies generally lack an intrinsic mesoporous structure, strongly limiting the investigation of the corresponding drug loading and release properties. Within this scope, this study focuses on the adsorption and release properties of high surface area, mesoporous ZnO structures using gentamicin sulfate (GS), a well known antibiotic against bacterial infections especially in orthopedics. The particular ZnO morphology was achieved starting from sputtered porous zinc layers, finally converted into ZnO by thermal oxidation. By taking advantage of this mesoporous framework, GS was successfully adsorbed within the ZnO matrix and the kinetic release profile evaluated for up to seven days. The adsorption of GS was successfully demonstrated, with a maximum amount of 263 mg effectively loaded per gram of active material. Then, fast kinetic release was obtained in vitro by simple diffusion mechanism, thus opening further possibilities of smart pore and surface engineering to improve the controlled delivery.

ZnO Nanostructures for Tissue Engineering Applications

This review focuses on the most recent applications of zinc oxide (ZnO) nanostructures for tissue engineering. ZnO is one of the most investigated metal oxides, thanks to its multifunctional properties coupled with the ease of preparing various morphologies, such as nanowires, nanorods, and nanoparticles. Most ZnO applications are based on its semiconducting, catalytic and piezoelectric properties. However, several works have highlighted that ZnO nanostructures may successfully promote the growth, proliferation and differentiation of several cell lines, in combination with the rise of promising antibacterial activities. In particular, osteogenesis and angiogenesis have been effectively demonstrated in numerous cases. Such peculiarities have been observed both for pure nanostructured ZnO scaffolds as well as for three-dimensional ZnO-based hybrid composite scaffolds, fabricated by additive manufacturing technologies. Therefore, all these findings suggest that ZnO nanostructures represent a powerful tool in promoting the acceleration of diverse biological processes, finally leading to the formation of new living tissue useful for organ repair.

Selective removal of cationic micro-pollutants using disulfide-linked network structures

Micropollutants are found in all water sources, even after thorough treatments that include membrane filtration. We have developed swellable di-sulfide covalent organic polymers (COPs) with great affinity towards cationic textile micropollutants.

Current–voltage characteristics influenced by the nanochannel diameter and surface charge density in a fluidic field-effect-transistor

Nonlinear variation of average ion current through a channel as a function of gate potential V_g for different channel diameters and surface charge densities.