Size Reduction Of Nanoparticles Research Articles

Spectrum reconstruction of experimentally produced nano-colloids using Mie theory

Aim: Synthesis of plasmonic nanoparticles, characterization, size detection by modeling. Methods: Colloidal plasmonic gold and silver nanoparticles were prepared by laser ablation with a 1,064 nm pulsed Nd:YAG laser with equal fractional volume and then were illuminated with its 532 nm second harmonic pulse. After the illumination process, we observed 1 nm blue shift in peak position of gold colloid and 4 nm blue shift in silver colloid. We observed a variation in the dielectric function due to nanoparticle size reduction in both samples. Using micrograph, size distribution was plotted and with the help of Mie theory and size dependent dielectric function, we reconstructed absorption spectrum to best fit the experimental spectrum and we estimated 12- and 16-fold increase in the number of Au and Ag nanoparticles respectively, due to illumination. Results: We have estimated size distribution of produced nanoparticles. Conclusions: We produced silver and gold colloids with ablation of their foils in water without any surfactant, and then we fragmented the nanoparticles colloids with an intense nanosecond laser and studied the effect of illumination on peak position and size distribution of colloids.

Effect of ball milling time on Sr0.7Sm0.3Fe0.4Co0.6O2.65 perovskites and their application as semiconductor layers in dye-sensitized solar cells

The practical utilization of TiO2 as a semiconductor in dye-sensitized solar cells (DSSCs) has been set back by poor visible light absorption, high charge carrier recombination, and low electrical conductivity, which reduce the power conversion efficiency (PCE) and sustainability of the device. In this respect, perovskites with excellent properties, such as large surface area, good optical properties, high electrical conductivity, and superior electrochemical stability, have recently emerged as promising alternatives capable of overcoming the drawbacks of TiO2. Herein, Sr0.7Sm0.3Fe0.4Co0.6O2.65 (SSFC) perovskites were prepared via the ball milling method at various milling times of 0, 5, and 10 h, and the obtained samples were denoted by SSFC-0, SSCF-5, and SSCF-10, respectively. Increasing the ball milling time led to a significant reduction in nanoparticle size and agglomeration, which, in turn, increased the surface area and electrical conductivity of the samples. As a consequence, the SSFC-10 perovskite exhibited the smallest average particle sizes (18.9 nm) with the largest surface area (61.8 m2 g−1) and minimum defects, which allowed for efficient electron transport, resulting in the best electrical conductivity of 49.8 S cm−1. Ultimately, DSSCs fabricated using SSFC-10 semiconductor layers achieved an optimum PCE of 6.01 %, which is an improvement of 8.67 %, 1.1 %, and 6.56 % for SSFC-0 (3.69 %), SSFC-5 (4.96 %), and TiO2 (5.64 %), respectively. Thus, varying the ball milling time can be used as an effective technique to tailor the physicochemical properties of SSFC to suit desired applications, particularly the fabrication of highly efficient and sustainable DSSC semiconductor layers.

Refining laser-induced dewetting for bimetallic Au–Pd nanoparticle synthesis on ZnO thin films: Optimizing fluence for substrate integrity

We report the fabrication of metal alloy Au–Pd nanoparticles on semiconductor thin film substrates (ZnO) by laser-induced dewetting. Employing a UV excimer laser, a single pulse was directed onto a three-layer film stack on a glass substrate: glass/ZnO/Au/Pd and glass/ZnO/Pd/Au. We simulated the temperature attained by the thin films enabling the prediction of energy thresholds required for melting the metal films but avoiding modifying the ZnO film. A specific range is reported of the pulse energy conducive to nanoparticle formation and the energy threshold required to modify the ZnO film beneath them. Depending on the pulse energy applied, the mean diameter of the nanoparticles varied from approximately 150 to around 70 nm. Notably, higher fluences resulted in smaller particles but also induced surface cracks in the ZnO film. Additionally, we observed a reduction in nanoparticle size with increased Pd content. Our results show that laser-induced dewetting can produce bimetallic alloy nanoparticles and, at the same time, ensure the preservation of the optical properties of the ZnO film. This approach opens avenues for tailoring material characteristics and expanding the range of applications of metal nanoparticles on semiconductor-based systems.

Caveolin-1 frame-shift mutation induces multifunctional alterations in human fibroblasts that are exosome-mediated

Caveolins, Cav1-3, are oligomeric proteins critical for the formation of membrane caveolae that regulate cell physiology. A de novo frameshift mutation (Cav1F160X) in Cav1 (Cav1M) was described in a patient with a progeria-like phenotype, lipodystrophy, and pulmonary hypertension. We hypothesize that Cav1M presents as a dominant negative protein that perturbs cellular physiology, particularly nuclear morphology, mitochondrial function, plasma membrane structure, and exocytic behavior. Transmission electron microscopy (TEM) of patient-derived dermal fibroblasts (Cav1M) showed abnormal nuclear shape, increased rough endoplasmic reticulum, and an increased number of autophagosomes. Cav1M cells present an abnormal mitochondrial size and shape, accompanied by a reduced mitochondrial capacity for energy production detected by Seahorse real-time oximetry analysis. In addition, we observed in the patient’s fibroblasts an altered pattern of Cav1 expression and distribution, with less Cav1 in caveolae membrane fractions, together with a reduced membrane cholesterol concentration and number of caveolae. Electron paramagnetic spectroscopy shows an altered localization of proteins commonly found in caveolae fractions and increased membrane fluidity. Interestingly, Cav1M fibroblasts showed 4-fold increase in exosome secretion. Nanoparticle tracking and TEM analysis revealed a significant reduction in nanoparticle size in Cav1M-derived exosomes. Normal human dermal fibroblasts (HDF) treated to express Cav1M (Cav1M1-159) or exogenously exposed to exosomes isolated from Cav1M fibroblasts showed altered nuclear morphology, exosome secretion profile, proteomics, and miRNA analysis. Our results indicate that mutations in the C-terminus of Cav1 lead to significant cellular alterations at different levels that can lead to morpho-functional features, energetic imbalances, membrane ultrastructure abnormalities, and exosome secretion and signaling alterations. These findings suggest a novel role of Cav1 that links several aspects of cell physiology, from plasma and nuclear membrane dynamics to exocytic behavior, that have potential implications in cellular communication impacting physiology and pathophysiology. 5R01HL091071. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Nanocomposite-Supported Polymeric Composites Prepared with Different Deposition Bases: Characterization and Application in X-ray Shielding

This study deals with the preparation of magnetite nanoparticles (NPs) via a coprecipitation method using several precipitation bases: binary precipitator (NH4OH), mono precipitator (NaOH), and weak precipitator (Ca(OH)2). The prepared magnetite NPs were identified using X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy-dispersive X-ray (EDX) analysis, surface area analysis, magnetic properties, Fourier-transformed infrared spectra (FT-IR), and ultra-violet UV–visible spectra. As a result, the phases of the produced magnetite NPs were unaffected by the use of various bases, but their crystallite sizes were affected. It was found that the binary base provided the smallest crystallite size, the mono base provided an average size, and the weak base provided the largest crystallite size. The UV–visible absorption spectroscopy investigation revealed that the absorption and the energy gap rose with a reduction in nanoparticle size. The prepared magnetite NPs were used to manufacture polymeric-based nanocomposites employed as protective shields from low-energy X-rays that are light in weight. These samples were identified using XRD, atomic force microscopy (AFM), and FT-IR spectroscopy. The crystallite size was slightly larger than it was in the case of magnetite NPs. This is consistent with the results of AFM. The interference between the two phases was observed in the results of the FT-IR spectra. The effects of the size of the magnetite NPs on the attenuation tests, linear attenuation coefficient, mass attenuation coefficient, half-value layer, and mean free path were investigated. The results showed that the efficiency of using manufactured shields increases with the decrease in the NPs size of the magnetite used as a reinforcement phase for a range of low operating voltages.

Development of TiO2-based photocatalysts with high photocatalytic activity under simulated solar light: Metoprolol degradation and optimization via Box-Behnken

The photocatalytic activity of N-doped TiO2 nanoparticles to degrade metoprolol (MET) has been investigated. The materials were synthesized via sol-gel method and characterized using different techniques. All materials revealed the formation of anatase phase, with a band gap energy close to 3.12 eV, which suggests that the N doping did not cause substantial variations as compared to pure TiO2. However, the TiO2-5%N photocatalyst exhibited a reduction in nanoparticle size and a surface area 0.4-fold larger than undoped TiO2. The influence of pH, catalyst concentration, and doping percentage was investigated through a Box-Behnken experimental design. Under the best conditions (0.5 g L−1 of TiO2-5%N, solution pH 6.0), 98% MET degradation and 42% mineralization could be achieved, and the process by-products were non-toxic to Artemia salina.

Transforming electrochemical hydrogen Production: Tannic Acid-Boosted CoNi alloy integration with Multi-Walled carbon nanotubes for advanced bifunctional catalysis

The dimensions of alloy nanoparticles or nanosheets have emerged as a critical determinant for their prowess as outstanding electrocatalysts in water decomposition. Remarkably, the reduction in nanoparticle size results in an expanded active specific surface area, elevating reaction kinetics and showcasing groundbreaking potential. In a significant leap towards innovation, we introduced tannic acid (TA) to modify multi-walled carbon nanotubes (MWCNTs) and CoNi alloys. This ingenious strategy not only finely tuned the size of CoNi alloys but also securely anchored them to the MWCNTs substrate. The resulting synergistic “carbon transportation network” accelerated electron transfer during the reaction, markedly enhancing efficiency. Furthermore, the exceptional synergy of Co and Ni elements establishes Co0.84Ni1.69/MWCNTs as highly efficient electrocatalysts. Experimental findings unequivocally demonstrate that TA-Co0.84Ni1.69/MWCNTs require minimal overpotentials of 171 and 294 mV to achieve a current density of ± 10 mA cm−2. Serving as both anode and cathode for overall water splitting, TA-Co0.84Ni1.69/MWCNTs demand a low voltage of 1.66 V at 10 mA cm−2, maintaining structural integrity throughout extensive cyclic stability testing. These results propel TA-Co0.84Ni1.69/MWCNTs as promising candidates for future electrocatalytic advancements.

Magnetic properties of Fe-doped NiO nanoparticles

Undoped and Fe-doped NiO nanoparticles were successfully synthesized using a lyophilization method and systematically characterized through magnetization techniques over a wide temperature range, with varying intensity and frequency of the applied magnetic fields. The Ni1-xFexO nanoparticles can be described by a core-shell model, which reveals that Fe doping enhances exchange interactions in correlation with nanoparticle size reduction. The nanoparticles exhibit a superparamagnetic blocking transition, primarily attributed to their cores, at temperatures ranging from above room temperature to low temperatures, depending on the Fe-doping level and sample synthesis temperature. The nanoparticle shells also exhibit a transition at low temperatures, in this case to a cluster-glass-like state, caused by the dipolar magnetic interactions between the net magnetic moments of the clusters. Their freezing temperature shifts to higher temperatures as the Fe-doping level increases. The existence of an exchange bias interaction was observed, thus validating the core-shell model proposed.

Eco-Friendly Cerium-Cobalt Counter-Doped Bi2Se3 Nanoparticulate Semiconductor: Synergistic Doping Effect for Enhanced Thermoelectric Generation.

Metal chalcogenides are primarily used for thermoelectric applications due to their enormous potential to convert waste heat into valuable energy. Several studies focused on single or dual aliovalent doping techniques to enhance thermoelectric properties in semiconductor materials; however, these dopants enhance one property while deteriorating others due to the interdependency of these properties or may render the host material toxic. Therefore, a strategic doping approach is vital to harness the full potential of doping to improve the efficiency of thermoelectric generation while restoring the base material eco-friendly. Here, we report a well-designed counter-doped eco-friendly nanomaterial system (~70 nm) using both isovalent (cerium) and aliovalent (cobalt) in a Bi2Se3 system for enhancing energy conversion efficiency. Substituting cerium for bismuth simultaneously enhances the Seebeck coefficient and electrical conductivity via ionized impurity minimization. The boost in the average electronegativity offered by the self-doped transitional metal cobalt leads to an improvement in the degree of delocalization of the valence electrons. Hence, the new energy state around the Fermi energy serving as electron feed to the conduction band coherently improves the density of the state of conducting electrons. The resulting high power factor and low thermal conductivity contributed to the remarkable improvement in the figure of merit (zT = 0.55) at 473 K for an optimized doping concentration of 0.01 at. %. sample, and a significant nanoparticle size reduction from 400 nm to ~70 nm, making the highly performing materials in this study (Bi2-xCexCo2x3Se3) an excellent thermoelectric generator. The results presented here are higher than several Bi2Se3-based materials already reported.

Reduction of nanoparticle size and promotion of cell membrane permeability by LED irradiation

To improve the efficiency of poly (D, L-lactic-co-glycolic acid) (PLGA) nanoparticles (NP) as a gene carrier for the transfection of human mesenchymal stem cells (hMSCs), we developed a light-emitting diode (LED)-induced gene delivery system. The size of NP produced at various LED wavelengths (blue, green, red, and NIR) was controlled in the colloidal state (a mixture of single particles and agglomerates). In addition, physical stimulation of cell membranes using two LED wavelengths (blue and near infrared (NIR)) altered their structure and facilitated the penetration of cells with extracellular substances. The reduction of NP size and increase in cell membrane permeability effectively increased gene delivery to cells and protein expression by improving transfection processes (cellular uptake, endosomal escape, and PEI-gene dissociation). The effects of 10 min irradiation at each LED wavelength were compared with those of the non-irradiated sample. The reduction of NP size by LED irradiation was confirmed using DLS, SEM, and Nanosight, and cell membrane permeability was assessed by confocal laser microscopy and FACS. Transfection efficiency was measured using confocal laser microscopy, FACS, and Western blot analysis. Among the tested LED wavelengths, NIR light irradiation was the most effective in reducing NP size and increasing cell membrane permeability. Conversely, blue light irradiation significantly increased gene delivery to cells by accelerating transfection processes. Thus, the LED-irradiation mediated NP dispersion method improved the delivery efficiency of PLGA NP as gene carrier, and by enhancing cell membrane permeability, extracellular substances that normally cannot easily penetrate the cell membrane were delivered in a timely and effective manner.

Use of artificial intelligence models for the reduction of nanoparticle size in the synthesis of ZnO

AbstractBACKGROUNDThis study evaluates the effectiveness of an artificial intelligence (AI) model for predicting the best experimental conditions to reduce particle size during the synthesis of ZnO nanoparticles. Firstly, an artificial neural networks (ANN) was trained using 52 experimental data from the synthesis of ZnO nanoparticles. The selected input variables were temperature, experimental time, and NaOH concentration, and the output variable was nanoparticle size. The performance of the ANN was measured with the root mean square error and mean absolute percentage error, and the obtained values for the selected ANN were 0.67% and 9.87%, respectively. These values were calculated by using real and predicted values.RESULTSA genetic algorithm (GA) model was coupled with the ANN to find the best operational conditions for the reduced size of ZnO nanoparticles. According to the AI model, a temperature of 59 °C, an experimental time of 56 min, and a concentration of NaOH of 0.08 should be tested to obtain ZnO nanoparticles with 5.67 nm of diameter. After applying the conditions predicted by the model, ZnO nanoparticles with a mean diameter of 5.3 ± 0.4 nm were obtained. The results were confirmed by using several characterization methods, such as approximation of effective masses (5.3 nm), equation Debye–Scherrer (5.2 nm), and high‐resolution transmission electron microscope (HR‐TEM) selected micrograph (5.5 nm). The photocatalytic activity of the synthesized nanoparticles was evaluated using the synthetic dye thymol blue. The best discoloration efficiency was reached by the synthesized ZnO nanoparticles at 74%, while the commercial ZnO only achieved 58%.CONCLUSIONAccording to the ANN‐GA model, it was possible to predict the experimental conditions needed to obtain ZnO nanoparticles with reduced sizes and excellent photocatalytic activity. © 2023 Society of Chemical Industry (SCI).

Osmotic Pressure as Driving Force for Reducing the Size of Nanoparticles in Emulsions.

We describe here a method to decrease particle size of nanoparticles synthesized by miniemulsion polymerization. Small nanoparticles or nanocapsules were obtained by generating an osmotic pressure to induce the diffusion of monomer molecules from the dispersed phase of a miniemulsion before polymerization to an upper oil layer. The size reduction is dependent on the difference in concentration of monomer in the dispersed phase and in the upper oil layer and on the solubility of the monomer in water. By labeling the emulsion droplets with a copolymer of stearyl methacrylate and a polymerizable dye, we demonstrated that the migration of the monomer to the upper hexadecane layer relied on molecular diffusion rather than diffusion of monomer droplets to the oil layer. Moreover, surface tension measurements confirmed that the emulsions were still in the miniemulsion regime and not in the microemulsion regime. The particle size can be tuned by controlling the duration during which the miniemulsion stayed in contact with the hexadecane layer, the interfacial area between the miniemulsion and the hexadecane layer and by the concentration of surfactant. Our method was applied to reduce the size of polystyrene and poly(methyl methacrylate) nanoparticles, nanocapsules of a copolymer of styrene and methyl methacrylic acid, and silica nanocapsules. This work demonstrated that a successful reduction of nanoparticle size in the miniemulsion process can be achieved without using excess amounts of surfactant. The method relies on building osmotic pressure in oil droplets dispersed in water which acts as semipermeable membrane.

Thermal analytical model of size reduction (fragmentation) of colloidal metal nanoparticles by short laser pulses

Theoretical investigations and estimations of significant size reduction of the metal spherical nanoparticles by the laser pulses in a liquid medium have been carried out. Thermal analytical model has been developed for this purpose. The conservation energy law is used for the estimations of the threshold laser fluencies leading to the nanoparticle size reduction. The analytical dependencies of threshold fluencies on pulse durations, laser wavelengths and nanoparticle radii have been established and discussed for nanosecond and picosecond laser pulses. Comparison of some predicted values of the threshold laser parameters for the wavelength 532 nm for size reduction of gold spherical nanoparticle in water with the experimental data is given and satisfactory agreement of these results validates the model developed. These model and results can be used for the investigation of the thermal processes of the nanoparticle processing and the applications in various laser technologies.

Phonon Scattering Mechanism for Size‐Dependent Thermoelectric Properties of Bi2Te3 Nanoparticles

AbstractThe effect of nanoparticle size on thermoelectric properties of Bi2Te3 nanoparticles is theoretically analysed using a phonon scattering mechanism. The size‐dependent thermoelectric properties in Bi2Te3 nanoparticles give an opportunity to tune the nanoparticles′ size, which helps to optimize the figure of merit (ZT=S2σT/κ). The thermoelectric effect in Bi2Te3 nanoparticles is investigated using the phonon scattering effect. Reduction in nanoparticle size increases interface volume ratio, which increases the scattering of phonons with grain boundaries. An increase in phonon‐grain boundary scatterings decreases the thermal conductivity (κ) due to the shortening of the phonon mean free path. The Seebeck coefficient (S) and simultaneously ZT increase significantly because of a decrease in lattice thermal conductivity. The highest value of ZT=0.45 is obtained at temperature T=400 K for 150 nm Bi2Te3 nanoparticles, which has been enhanced up to ZT=0.92 by reducing the nanoparticles size up to 30 nm at the same temperatures. The results obtained from the present model are in good agreement with the experimental data and reflect that the thermoelectric properties are dominated by the phonon scattering mechanism and depend on the density of interfaces in the material. Numerical analysis of thermoelectric properties from the present investigation will help in designing efficient thermoelectric materials.

Laser Assisted Synthesis of Surfactant-Free Au-Ag Alloy Nanoparticles in Water

Surfactant-free nontoxic Au-Ag alloy nanoparticles were synthesized via re-irradiation of laser generated mono metallic colloidal mixtures with 532 nm radiations from Nd: YAG nanosecond laser. The impact of re-irradiating laser energy in alloy formation kinetics was investigated. The alloy formation process was analyzed with UV-Visible absorption spectra at different time intervals of laser irradiation. The generated nanoparticles were characterized with dynamic light scattering size analysis, zeta potential studies, and HRTEM imaging. Photothermal properties of the samples were investigated employing thermal lens method. Alloy formation became faster with a slight blue shift in the plasmonic band wavelength with increase in irradiation energy. Reduction in nanoparticle size and stability were also observed at high irradiation energies.

Enhancing laser-nanoparticle interactions by diffused laser beams: efficient size-reduction of nanoparticles

Generally speaking, a laser beam with a good spatial profile such as flat-top or Gaussian (TEM00 mode) shape is considered to be a prerequisite to maximize laser-matter interactions. On the contrary, we show that if the process of interest has a threshold in terms of laser fluence or intensity, a diffused laser beam can do a good job of inducing the process. As an example, we demonstrate the efficient size-reduction of colloidal nanoparticles by a diffused laser beam and identify that the physical origin of this counterintuitive results is a redistribution of laser energy, i.e. formation of speckles through a diffuser where the local laser fluence exceeds the size-reduction threshold. We report the systematic results for silver and gold nanoparticles.

Nanoreinforced biodegradable gelatin based active food packaging film for the enhancement of shelf life of tomatoes (Solanum lycopersicum L.)

The major chunk of fresh farm produce in world is wasted due to improper packaging and handling. The current study focuses on tailoring of properties of copper oxide (CuO) nanoparticles to make them fit in active food packaging applications. A facile customized co-precipitation approach was used for synthesis of gelatin stabilized Titanium (Ti)-doped CuO nanoparticles., Their physico-chemical properties, confirmed the reduction in size of nanoparticles after doping from 92 to 94 nm for pure CuO nanoparticles to 10–13 nm for Ti-doped CuO nanoparticles with better antimicrobial activity and lower cytotoxicity against animal cells. Furthermore, Ti-doped CuO nanoparticles were found to be cream of the crop to be incorporated into gelatin based active food packaging films to achieve desired functionality, with complete decomposition into natural soil (9 days). The shelf life of tomatoes ( Solanum lycopersicum L.) was greatly enhanced (up to 18 days at 40 ± 3 °C) with the use of nanoreinforced active food packaging films. • Ti-Doped CuO nanoparticles were synthesized via customized precipitation approach. • These nanoparticles showed potent antimicrobial effect with lower cytotoxicity. • Nanoreinforced active food packaging film was prepared with enhanced functionality. • The shelf life of tomatoes was greatly enhanced with the use of active package.

Synthesis and growth of spherical ZnO nanoparticles using different amount of plant extract

The use of plant extracts has become an interesting ecofriendly method to synthesize and stabilize the different structures nanoparticles (NPs). This work investigated the effect of plant extract as a reducing and stabilizing agent on the growth and morphology of ZnO nanoparticles (ZnO-NPs). Green synthesis and growth of spherical ZnONPs was carried out by co-precipitation method using a Zinc acetate salt and various amounts of Azadirachta indica seed husk extract (20 ml and 40 ml). The synthesized ZnO-NPs were characterized by Fourier transform infrared (FTIR), scanning electron microscopy (SEM-EDX), and transmission electron microscopy (TEM). The FTIR analyses revealed the presence of Phenolic alcohol, amines and carboxylic acid groups and ZnO in synthesized NPs with more intense peaks at higher amount (40 ml) of A. indica extract. Also, structural morphology analyses using SEM revealed uniform spherical shaped particles with diameter from 25 to 60 nm (20 ml of extract) and 19 to 35 nm (40 ml of extract) for ZnO-NPs. The EDX spectral revealed that the required phase of Zn and O was present 69.54% (Zn) and 30.46% (O) at 20 ml of extract, also 73.71% (Zn), 26.26% (O) at 40 ml of extract respectively and confirmed high purity for the synthesized ZnO NPs. TEM revealed spherical shaped NPs with diameter ranging from 28 to 52 nm (20 ml of extract) and 8.2 to 11.9 nm (40 ml of extract) respectively, with a trend reduction in particle size of NPs at higher amount of A. indica seed extract (40 ml) and growth of more uniform particles with no agglomeration. The study showed successful growth of spherical ZnO-NPs with required properties at a higher amount of extract.

Shear-Thinning Effect of the Spinning Disc Mixer on Starch Nanoparticle Precipitation

Spinning disc technology is capable of achieving intensified micromixing within thin liquid films created through large shear rates, typically of the order of 103 s−1, generated by means of fast disc surface rotation. In this study the effect of the high shear on solvent–antisolvent mixing and starch nanoparticle precipitation is reported. Rheological studies of starch solutions at 2% w/v and 4% w/v have demonstrated their shear-thinning behaviour at the large shear rates experienced on the spinning disc surface. The effect of such high shear rate on starch nanoparticle precipitation is investigated alongside solute concentration and several other operating parameters such as flow rate, disc rotational speed, and solvent/antisolvent ratio. A reduction in nanoparticle size has been observed with an increase in starch concentration, although agglomeration was found to be more prevalent amongst these smaller particles particularly at larger flow rates and disc rotational speeds. Micromixing time, estimated on the basis of an engulfment mechanism, has been correlated against shear rate. With fast micromixing of the order of 1 ms observed at higher shear rates, and which are practically unaffected by the starch concentrations used, micromixing is not thought to be influential in determining the particle characteristics highlighted in this work.

Size dependent thermodynamic properties of nanoparticles

Surface effect and crystal structure lead to formulating a theoretical model to study the influences of size on thermodynamic parameters, such as melting temperature, Debye temperature, melting entropy and specific heat capacity, of nanoparticles. The cohesive energy as a thermodynamic quantity was used to relate the ratio of surface area to volume of nanomaterial with thermodynamic properties which depend on size of the nanomaterial. In this contribution, Si and Au nanoparticles were considered to study due to their potential applications in science and technology. It was found that melting temperature, Debye temperature, melting entropy of nanoscale size material is decreased with decreasing the size up to their critical sizes. Whereas, the specific heat capacity tends to enhance with reduction in nanoparticle size. The present results for melting temperature, melting entropy and Debye temperature are compared with experimental and theoretical observations and adequate agreements are observed.