Decrease In Size Of Nanoparticles Research Articles

Surfactant Composition Dependent Evolution of Electronic/Structural Properties of P3HT Nanoparticle Colloids Synthesized via Mini-Emulsion Technique

: This study investigates the influence of surfactant (sodium dodecyl sulfate, SDS) concentration on the size and optoelectronic properties of poly(3-hexylthiophene) (P3HT) nanoparticles (NPs) synthesized via the mini-emulsion technique. P3HT NPs were fabricated with varying SDS concentrations. The size dependent optoelectronic properties, including the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) levels, were analyzed through photoelectron spectroscopy in air, UV-Vis absorption spectroscopy and cyclic voltammetry. A clear trend of decreasing NP size with increasing SDS concentration was observed. Higher SDS levels resulted in smaller NPs with enhanced pi-pi stacking and shorter conjugation lengths. This structural change led to a noticeable shift in HOMO and LUMO levels, indicating a direct correlation between surfactant concentration and the electronic properties of the P3HT NPs. The absorption spectra revealed a decrease in the A0-0/A0-1 ratio with smaller NP size, suggesting a transition towards more pronounced H-aggregate characteristics. As the size of the P3HT NPs decreases, there is a notable increase in H-aggregate formation. This increase can be attributed to enhanced interchain interactions between the polymer chains. In smaller NPs, the surface area-to-volume ratio is higher, leading to more significant interactions between adjacent polymer chains. These interactions promote the formation of H-aggregates, characterized by their interchain pi-pi stacking, which differs from the intrachain coupling observed in J-aggregates.

Investigation of Optical Characteristics and Synthesis of Cobalt-Doped Cds (Cds: Co) Using Simple and Rapid Microwave Activated Method

Cobalt-doped cadmium sulphide semiconductor nanoparticles (CdS: Co NPs) were made using a microwave-assisted method with different cobalt concentrations. Chemicals like sodium sulphide, cobalt chloride, and cadmium acetate were used. The Debye-Scherer equation helped find the nanoparticles' size, revealing a 2 to 4 nm range. X-ray diffraction showed a zinc-blend structure. The optical bandgap energies were found to be undoped and doped are 2.44eV and 2.58eV, respectively. For pure CdS, the XRD spectra display three main peaks at 2θ = 26.68°, 44.16°, and 52.32°. Modest alterations have been noted in 2θ for Co doping levels of 3% in CdS NPs. The peaks point to the samples' cubic structure and correlate to the (1 1 1), (2 2 0), and (3 1 1) planes. The sizes of the nanoparticles, which are 2.29 nm, 3.64 nm, for pure and Co (3%) doped CdS, were determined using the FWHM and Debye Scherer equation. The substitution of Co2+ion for Cd2+ion may be the cause of the decrease in nanoparticle size observed in the Co-doped CdS sample as concentration rises. The difference in the ionic radii of Cd2+ (0.98 Å) and Co2+ (0.72 Å) shows that when the concentration of Co-doped CdS increases, the lattice constant falls. The peak at 3646 cm-1 in the higher energy area of the 400–4000 cm–1 FTIR spectra is attributed to the O–H stretching of absorbed water on the surface of CdS. Its bending vibration confirms the existence of water. Using HRTEM, the size of the produced nanoparticles was examined. Additionally, it confirms the sample's nanocrystalline structure. For 3% Co-doped CdS, the average size of randomly chosen nanoparticles is determined.

Doping Effects on the Multiferroic Properties of KNbO3 Nanoparticles

The magnetization, polarization, and band-gap energy in pure and ion-doped KNbO3 (KNO) bulk and nanoparticles (NPs) are investigated theoretically using a microscopic model and Green’s function theory. It is shown that KNO NPs are multiferroic. The size dependence of M and P is studied. The magnetization M increases with decreasing NP size, whereas the polarization P decreases slightly. The properties of KNO can be tuned by ion doping, for example, through the substitution of transition metal ions at the Nb site or Na ions at the K site. By ion doping, depending on the relation between the doping and host ion radii, different strains appear. They lead to changes in the exchange interaction constants, which are inversely proportional to the lattice parameters. So, we studied the macroscopic properties on a microscopic level. By doping with transition metal ions (Co, Mn, Cr) at the Nb site, M increases, whereas P decreases. Doped KNO NPs exhibit the same behavior as doped bulk KNO, but the values of the magnetization and polarization in KNO NPs are somewhat enhanced or reduced due to the size effects compared to the doped bulk KNO. In order to increase P, we substituted the K ions with Na ions. The polarization increases with increasing magnetic field, which is evidence of the multiferroic behavior of doped KNO bulk and NPs. The behavior of the band-gap energy Eg also depends on the dopants. Eg decreases with increasing Co, Mn, and Cr ion doping, whereas it increases with Zn doping. The results are compared with existing experimental data, showing good qualitative agreement.

Mechanistic Analysis of Temperature-Dependent Curcumin Release from Poly(lactic-co-glycolic acid)/Poly(lactic acid) Polymer Nanoparticles.

In this study, we investigated the mechanism of curcumin (CUR) release from poly(lactic-co-glycolic acid) (PLGA) and poly(lactic acid) (PLA) nanoparticles (NPs) by evaluating the temperature-dependent CUR release. NPs were prepared by the nanoprecipitation method using various PLGA/PLA polymers with different lactic:glycolic ratios (L:G ratios) and molecular weights. Increasing the polymer molecular weight resulted in a decrease in the particle size of NPs. The wet glass transition temperature (Tg) of PLGA/PLA NPs was lower than the intrinsic polymer Tg, which can be derived from the water absorption and nanosizing of the polymer. The reduction in Tg was more significant for the PLGA/PLA NPs with lower polymer L:G ratios and lower polymer molecular weight. The greater decrease of Tg in the lower polymer L:G ratios was possibly caused by the higher water absorption due to the more hydrophilic nature of the glycolic acid segment than that of the lactic acid segment. The efficient water absorption in PLGA/PLA NPs with lower molecular weight could cause a significant reduction of Tg as it has lower hydrophobicity. CUR release tests from the PLGA/PLA NPs exhibited enhanced CUR release with increasing temperatures, irrespective of polymer species. By fitting the CUR release profiles into mathematical models, the CUR release process was well described by an initial burst release followed by a diffusion-controlled release. The wet Tg and particle size of the PLGA/PLA NPs affected the amount and temperature dependence of the initial burst release of CUR. Above the wet Tg of NPs, the initial burst release of CUR increased sharply. Smaller particle sizes of PLGA/PLA NPs led to a higher fraction of initial CUR burst release, which was more pronounced above the wet Tg of NPs. The wet Tg and particle sizes of the PLGA/PLA NPs also influenced the diffusion-controlled CUR release. The diffusion rate of CUR in the NPs increased as the wet Tg values of the NPs decreased. The diffusion path length of CUR was affected by the particle size, with larger particle size resulting in a prolonged diffusion-controlled release of CUR. This study highlighted that for the formulation development of PLGA/PLA NPs, suitable PLGA/PLA polymers should be selected considering the physicochemical properties of PLGA/PLA NPs and their correlation with the release behavior of encapsulated drugs at the application temperature.

Fast quenching of manganese emission in ZnS:Mn2+ nanoparticles

The Monte Carlo method was used to calculate static dipole-dipole (Förster) quenching of manganese luminescence in nanoparticles of various sizes in the semi-magnetic semiconductor Zn0.99Mn0.01S. For the first time, the quenching is stated to play insignificant role in sub-nanosecond huge drop of the emission transient. Parameter values of Förster's quenching stage of luminescence transient – characteristic quenching distance, concentration of quenchers, average quenching rate, probability of quencher absence in a nanoparticle, quenching amplitude, etc. − were found from a comparison of calculations with experimental transients. The values are dependent on nanoparticle growth technology. Calculations show that luminescence efficiency increases with a decrease in actual size of nanoparticles, while probability of obtaining nanoparticles without quenchers asymptotically approaches unity at smaller size. The latter condition together with agglomeration absence and greater intrinsic time decay are the main conditions for higher efficiency of manganese luminescence in ZnS:Mn2+ nanoparticles. The analysis of previous researches and our experiments showed that the most fast transient component originated from ZnS host.

Lowering the pH leads to the disaggregation of NiO and ZnO nanoparticles and modifies the mutagenic response.

In a changing environmental scenario, acid rain can have a significant impact on aquatic ecosystems. Acidification is known to produce corrosion in metals, hence increasing their harmful effects on the environment, organisms and human health. The prevalent use of metallic nanoparticles (NPs) in everyday products raises concerns regarding exposure and nanotoxicity even in these acidified conditions. We thus report on the cytotoxic and genotoxic potential of nickel oxide (NiO-NP) and zinc oxide (ZnO-NP) NPs when suspended in aqueous media in light of pH variations (7.5 and 5). A modified microsuspension method of the Salmonella/microsome assay was adopted, and strains (TA97a, TA98, TA100, TA102) were exposed to NPs (10-1280 μg/plate) with and without a metabolization fraction. The acidic condition favored disaggregation and caused a decrease in NPs size. Mutagenicity was observed in all samples and different strains, with greater DNA base pair substitution damage (TA100 and TA102), but extrinsic conditions (pH) suggest different action mechanisms of NiO-NP and ZnO-NP on genetic content. Mutagenic activity was found to increase upon metabolic activation (TA98, TA100, and TA102) demonstrating the bioactivity of NiO-NP and ZnO-NP in relation to metabolites generated by the mammalian p450 system in vitro. Modifications in the Salmonella assay methodology increased cell exposure time. The observed responses recommend this modified assay as one of the methodologies of choice for nanoecotoxicological evaluation. These findings emphasize the significance of incorporating the environmental context when evaluating the toxicity of metal-based NPs.

Sublethal Effects of Polystyrene Nanoplastics on the Embryonic Development of Artemia salina (Linnaeus, 1758).

Currents, wave motion, solar radiation, and abrasion are mechanisms responsible for the degradation of large plastic artifacts and contribute to the dispersion of micro and nanoplastics into aquatic ecosystems, which are, currently, the most dangerous threats due to their invisibility and persistence. The present work evaluated the possible lethal and sublethal effects of amino-modified polystyrene nanoplastics (nPS-NH2) with diameters of 50 nm and 100 nm on Artemia salina (A. salina), an organism at the base of the trophic chain of the aquatic system, using a widely used model for the analysis of embryotoxicity from environmental pollutants. For this purpose, after evaluating the biodistribution of nanoplastics in the body of the tested animals, several endpoints such as anomalies, apoptosis, and ROS production were assessed. In addition, particular attention was dedicated to evaluating the correlation between toxicity and the particle size tested. The results reported that, despite the absence of a lethal impact, several sublethal effects involving gut and body size malformations, as well as the enhancement of apoptosis and oxidative stress in relation to an increase in tested concentration and a decrease in nanoparticle size.

Effect of Nanoparticles Deposition on Cooling Performance of Photovoltaic Panels

Abstract The current research aims to investigate the deposition and dispersion of nanoparticles for thermally developing laminar flow inside a cooling channel of a photovoltaic (PV) panel. The particle transport is modeled in an Eulerian-Lagrangian framework using a two-way coupling approach to perform the particle trajectories. In the absence of turbulent fluctuations, Brownian diffusion is the main force that contributes to particles deposition due to the small size of the particles used in the current study (below 100 nm). Several parameters were investigated such as inlet temperature, Reynolds number, nanoparticle size, and concentration in order to record the subsequent effects on the deposition efficiency, heat transfer coefficient, and pressure drop. There is no direct particle deposition model available in commercial computational packages such as Fluent, so a deposition model was developed and programmed in C-language using the User-Defined Functions (UDF) capabilities available in the Fluent solver to model how the particles are affected by wall impacts. Model validation was performed against the experimental studies found in the literature and showed good agreement. The efficiency of particle deposition on the channel wall was found to increase with decreasing nanoparticle size and/or Reynolds number. Furthermore, the deposition efficiency increased with the increase in fluid inlet temperature and nanofluid concentration. Moreover, the heat transfer rate was decreased as a result of decreasing nanofluid concentration caused by nanoparticle deposition on the channel walls, while the pumping power was also decreased due to concentration loss.

(Invited) Unique Size-Dependent Electrochemistry of Metal Nanoparticles in Aqueous and Hydrogel Environments

Metal nanoparticles (NPs) exhibit unique size-dependent physical and chemical properties, providing many potential applications including sensing, catalysis, optoelectronics, medical diagnostics and disease therapeutics, among others. Here we describe interesting size-dependent metal oxidation, metal reduction, and electrocatalytic properties for Au and other metal nanoparticles that are coated with relatively weak-binding stabilizers, which is necessary for effective electron transfer at the metal NP surface. Metal oxidation potentials decrease dramatically negative with decreasing NP size, especially below 4 nm down to ~1 nm in radius. Electrocatalytic seeded-growth kinetics also depend strongly on the metal NP size (seed size). The thermodynamics of other oxidation/reduction reactions, such as galvanic replacement, also depend dramatically on metal NP size, resulting in unique alloy nanostructures with improved electrocatalytic reactivity and stability. Size-dependent electrophoretic deposition of metal nanoparticles to form thin films also results from size-dependent electrocatalytic properties, allowing metal NP separations based on electrocatalytic activity. These oxidation, reduction, galvanic replacement, and electrocatalytic properties change dramatically when the metal NPs are coated with strong ligand stabilizers or when placed in a viscous hydrogel environment. The effect of the ligand and environment will be described here. A better understanding of size-dependent reactivity of metal NPs as a function of the type of stabilizer and environment is important to realize their potential for tuning the properties to optimize them for a specific application.

Band Gap Energy of Ion‐Doped Multiferroic NaFeO2 Nanoparticles

The band gap energy Eg of orthorhombic β‐ and hexagonal α‐NaFeO2‐bulk and nanoparticles is investigated for the first time based on a microscopic model combined with Green's function theory. Eg increases with decreasing nanoparticles size and is shape‐dependent. The competition between Coulomb and electron–phonon interactions is demonstrated. Moreover, Eg decreases with increasing Ge and Si doping concentration or increases by Mn, Cr, and Ni ion doping due to different radii of the doping and the host Fe ions, leading to varying strains. The substitution for Na ion by K or Li(Cu) ions can cause both enhancing or reducing of Eg. Thus, the band gap energy can be regulated by nanoparticles size, ion doping, electron–phonon, and Coulomb interactions.

Photocatalytic degradation of organic pollutants and inactivation of pathogens under visible light via SnO2/rGO composites

The domains of environmental cleanup and pathogen inactivation are particularly interesting in nanocomposites (NCs) due to their exceptional physicochemical properties. Tin oxide/reduced graphene oxide nanocomposites (SnO2/rGO NCs) have potential uses in the biological and environmental fields, but little is known about them. This study aimed to investigate the photocatalytic activity and antibacterial efficiency of the nanocomposites. The co-precipitation technique was used to prepare all the samples. XRD, SEM, EDS, TEM, and XPS analyses were employed to characterize the physicochemical properties of SnO2/rGO NCs for structural analysis. The rGO loading sample resulted in a decrease in the crystallite size of SnO2 nanoparticles. TEM and SEM images demonstrate the firm adherence of SnO2 nanoparticles to the rGO sheets. The chemical state and elemental composition of the nanocomposites were validated by the XPS and EDS data. Additionally, the visible-light active photocatalytic and antibacterial capabilities of the synthesized nanocomposites were assessed for the degradation of Orange II and methylene blue, as well as the suppression of the growth of S. aureus and E. coli. As a result, the synthesized SnO2/rGO NCs are improved photocatalysts and antibacterial agents, expanding their potential in the fields of environmental remediation and water disinfection.

Magnetic Properties of Gd-Doped Fe3O4 Nanoparticles

The magnetic properties of pure and rare earth ion-doped Fe3O4 nanoparticles are investigated using a microscopic model and the Green’s function theory. The magnetization Ms and Curie temperature TC are calculated depending on size, temperature and Gd doping concentration. Ms and TC decrease with decreasing nanoparticle size and with increasing the doping concentration. The band gap energy increases with decreasing size and Gd dopants. The obtained results are in good agreement with the experimental data.

Magnetic, Optical and Phonon Properties of Ion-Doped MgO Nanoparticles. Application for Magnetic Hyperthermia

The influence of size and doping effects on the magnetization M, phonon ω and band gap energy Eg of MgO nanoparticles is studied using a microscopic model. The room-temperature ferromagnetism is due to surface or/and doping effects in MgO nanoparticles (NPs). The influence of the spin-phonon interaction is discussed. M increases with decreasing NP size. M and Eg can increase or decrease by different ion doping (Co, Al, La, Fe) due to the different strain that appears. It changes the lattice parameters and the exchange interaction constants. We found that MgO NP with size of 20 nm and Fe- or Co-doping concentration x = 0.1 and x = 0.2, respectively, have a Curie temperature TC = 315 K, i.e., they are appropriate for application in magnetic hyperthermia, they satisfy the conditions for that. The energy of the phonon mode ω = 448 cm-1 increases with decreasing NP size. It increases with increasing Co and Fe, or decreases with Sr ion doping.

Differences between the multiferroic properties of hexagonal and orthorhombic ion-doped YFeO3nanoparticles

The multiferroic properties of ion-doped hexagonal and orthorhombic YFeO3(YFO) nanoparticles (NPs) are studied theoretically. The magnetization [Formula: see text] in h-YFO NPs increases, whereas for o-YFO NPs it decreases with decreasing NP size. In the dielectric constant (DC) both h- and o-YFO have a peak around [Formula: see text] and 460 K, respectively, but only in h-YFO an anomaly appears at [Formula: see text] K in the DC and the polarization which could be connected with a possible [Formula: see text]–[Formula: see text] phase transition. The polarization in pure and Bi-doped o-YFO NPs increases with increasing magnetic field. [Formula: see text] is studied by doping of a o-YFO NP with Ti[Formula: see text] ions at the octahedral Fe[Formula: see text] sites. [Formula: see text] in undoped YFO shows a small kink at [Formula: see text] K, whereas in the doped YFO it shows at [Formula: see text]480 K. By different ion doping on the Y or Fe sites in YFO there is a transformation from the h- to the o-phase or vice versa. In Mn-doped o-YFO a spin-reorientation transition appears. The bandgap of h-YFO is smaller compared to that of o-YFO.

Simultaneous electro-generation/polymerization of Cu nanocluster embedded conductive poly(2,2′:5′,2′′-terthiophene) films at micro and macro liquid/liquid interfaces

Cu nanoparticles (NPs) have been shown to be excellent electrocatalysts, particularly for CO2 reduction – a critical reaction for sequestering anthropogenic, atmospheric carbon. Herein, the micro interface between two immiscible electrolyte solutions (ITIES) is exploited for the simultaneous electropolymerization of 2,2′:5′,2′′-terthiophene (TT) and reduction of Cu2+ to Cu nanoparticles (NPs) generating a flexible electrocatalytic composite electrode material. TT acts as an electron donor in 1,2-dichloroethane (DCE) through heterogeneous electron transfer across the water|DCE (w|DCE) interface to CuSO4 dissolved in water. The nanocomposite formation process was probed using cyclic voltammetry as well as electrochemical impedance spectroscopy (EIS). CV and EIS data show that the film forms quickly; however, the interfacial reaction is not spontaneous and does not proceed without an applied potential. At high [TT] the heterogeneous electron transfer wave was recorded voltammetrically but not at low [TT]. However, probing the edge of the polarizable potential window was found to be sufficient to initiate electrogeneration/electropolymerization. SEM and TEM were used to image and analyze the final Cu NP/poly-TT composites and it was discovered that there is a concomitant decrease in NP size with increasing [TT]. Preliminary electrocatalysis results at a nanocomposite modified large glassy carbon electrode saw a > 2 × increase in CO2 reduction currents versus an unmodified electrode. These data suggest that this strategy is a promising means of generating electrocatalytic materials for carbon capture. However, films electrosynthesized at a micro and ~ 1 mm ITIES demonstrated poor reusability.

Intensified Nonequilibrium Effect of Polymer Nanocomposites with Decreasing Nanoparticle Size.

What are the most important and decisive parameters that determine the structure and the property of polymer nanocomposites (PNCs)? Previous studies answered that controlling the nanoparticle interface is critical, which can be achieved with a choice of a compatible nanoparticle, a proper surface modification, and a change in the polymer chain length. In addition to these parameters, the processing condition of PNCs has recently emerged as an influential parameter for controlling PNC properties, suggesting the existence of the nonequilibrium effect of PNCs. In this regard, we chose the solvent as a main change in the processing condition and investigated the initial solvent-driven nonequilibrium effect of PNCs with varied nanoparticle (NP) sizes. We found that the type of the initial solvent is indeed crucial in determining the ultimate properties of the PNCs, and this becomes more influential as the size of NPs decreases. The decreasing size of NPs causes a conformational change in the adsorbed polymers from tightly packed layers to loosely dangling chains. This results in much greater differences in NP microstructures and rheological properties of PNCs, indicating a stronger nonequilibrium effect with smaller NPs.

TRANSIENT ABSORPTION OF GOLD NANOPARTICLES OF VARIOUS DIAMETERS

excitation by nanosecond laser pulses has been studied. It was shown that the maximum of stationary absorption exhibits as a wide structureless band with a maximum at about 520–540 nm. The transient absorption band of gold nanoparticles with a maximum at about 430 nm has a fine structure with a frequency of maxima of 6–8 nm and it does not depend on the size of the nanoparticles. The absorption duration decreases with a decrease in the average size of nanoparticles. The lifetime of transient absorption is equal to 23±2 and 19.5±2 ns for large and small particles, respectively. The nanosecond lifetime of the transient absorption of Au nanoparticles is the result of a prolonged relaxation process in the “interface of Au nanoparticle–solvent molecule” system as a manifestation of hindered heat exchange with the environment.

HSBM-Produced Zinc Oxide Nanoparticles: Physical Properties and Evaluation of Their Antimicrobial Activity against Human Pathogens.

This work examines the antibacterial and anticandidal activities of zinc oxide nanoparticles (ZNPs) synthesized by high-speed ball milling (HSBM), for short milling times: 0.5, 1, 1.5, and 2 h. First, ZNPs have been characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy, and the Zetasizer analyzer. The HSBM results in semispherical ZNPs with some local agglomeration. We found that nanoparticles decrease in size continuously with milling time until they reach about 84% of their original size after only two hours; at 1000 rpm, HSBM reduces ZNP's average size by 6 nm/min. As particle size decreases, the X-ray diffracted patterns become broader and less intense while confirming that no phase transformation has occurred, proving HSBM's effectiveness in synthesizing nanoparticles on a large scale within a short period of time. According to FT-IR analysis, as material sizes change, the polarization charge of the ZNP surface changes as well, creating discrepancies in vibrational frequency, as demonstrated by the shifting of the IR spectra in the 300-600 cm-1 frequency band. Raman responses have also been proven to depend on the particle size. Using the Agar well diffusion method, eleven microorganisms have been tested for the antimicrobial activity of ZNPs. Among the six Gram-negative tested bacteria, S. sonnei showed the largest inhibition zone of about 11.3 ± 0.6 mm with ZNPs measuring 148 nm in size (milled for 2 h), followed by E. coli ATCC 25922. Accordingly, S. aureus was the most susceptible Gram-positive bacteria, with inhibition zone size gradually increasing from 11.8 ± 0.3 mm to 13.5 ± 0.5 mm with decreasing nanoparticle size from 767 to 148 nm, while S. aureus ATCC 25923 was resistant to both milled and unmilled samples. Similar results were seen with candida, all milled ZNPs inhibited C. albicans, followed by C. tropicalis, whereas C. knisei was resistant to all ZNP sizes. In light of microorganism-ZNP interaction mechanisms, the obtained results have been discussed in depth.

Antimicrobial edible materials via nano-modifications for food safety applications

Abstract Edible films from carboxymethyl cellulose (CMC)/starch incorporated with titanium dioxide (TiO2) nanoparticles were developed. The prepared films were characterized by Fourier transforms infrared, X-ray diffraction, transmission electron microscopy, dynamic light scattering, swelling behaviour, and thermal and mechanical properties. Results showed a decrease in the average particle size of TiO2 nanoparticles with increasing irradiation dose up to 30 kGy. The swelling capacity of CMC/starch blends is ordered in the sequence of composition ratio 2:1 > 1:1 > 1:2. The effect of different irradiation doses (2.5, 5, 10, 15, and 20 kGy) and different concentrations of TiO2 (0.5, 1, 1.5, 2, 2.5, and 3 wt%) on the film properties was evaluated. The tensile strength increased gradually, accompanied by a decline in elongation percentage with the increase in the irradiation dose and increase in the TiO2 contents up to 2.5 wt%. The irradiated CMC/starch/TiO2 film showed higher thermal stability than CMC/starch film. Furthermore, the unirradiated and irradiated CMC/starch/TiO2 edible films were applied to fresh strawberries by surface coating. The irradiated film showed a superior effect in prolonging the fruits’ shelf life. The antimicrobial activity of CMC/starch/TiO2 film against Escherichia coli and Staphylococcus aureus was increased by increasing the irradiation dose. In conclusion, CMC/starch/TiO2 edible film exhibited the prerequisite behaviour for potential application in active food packaging.

Size and Ion-Doping Effects on Magnetic, Optical, and Phonon Properties of CuAlO2 Nanoparticles

The magnetic, optical, and phonon properties of ion-doped CuAlO2 nanoparticles on the Cu or Al site are theoretically investigated. The room temperature ferromagnetism in CuAlO2 nanoparticles can be due to the surface, size, and doping effects. The magnetization increases with the decreasing nanoparticle size. The different radii of the transition metal ion and the host Cu ion lead to compressive strain, to the enhancment of the exchange interaction constants, and to increased magnetization Ms and Curie temperature TC. By substitution with Mn or Cr on the Al site, tensile strain, a decrease in Ms, and an increase in dopants are observed. The size and ion-doping influence on the band-gap energy is also discussed. The phonon energy ω decreases, whereas the phonon damping γ increases with increasing temperature and decreasing NP size. They show a kink around TC ∼ 400 K. The behavior of ω and γ for different ion dopings is observed.