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Abstract: The increasing realisation of the impact of size and surface properties on the bio-distribution of drug loaded colloidal particles has driven the application of micro fabrication technologies for the precise engineering of drug loaded microparticles. This paper demonstrates an alternative approach for producing size controlled drug loaded PLGA based microparticles using silicon Microfluidic Flow Focusing Devices (MFFDs). Based on the precise geometry and dimensions of the flow focusing channel, microparticle size was successfully optimised by modifying the polymer type, disperse phase (Q d) flow rate, and continuous phase (Q c) flow rate. The microparticles produced ranged in sizes from 5 to 50μm and were highly monodisperse (coefficient of variation <5%). A comparison of Ciclosporin (CsA) loaded PLGA microparticles produced by MFFDs vs conventional production techniques was also performed. MFFDs produced microparticles with a narrower size distribution profile, relative to the conventional approaches. In-vitro release kinetics of CsA was found to be influenced by the production technique, with the MFFD approach demonstrating the slowest rate of release over 7 days (4.99±0.26%). Finally, MFFDs were utilised to produce pegylated microparticles using the block co-polymer, PEG-PLGA. In contrast to the smooth microparticles produced using PLGA, PEG-PLGA microparticles displayed a highly porous surface morphology and rapid CsA release, with 85±6.68% CsA released after 24h. The findings from this study demonstrate the utility of silicon MFFDs for the precise control of size and surface morphology of PLGA based microparticles with potential drug delivery applications. [Copyright &y& Elsevier]

Monodispersed silver (Ag) nanoparticles (NPs) were obtained by applying an electric field on unipolar-charged Ag NPs fabricated using a heterogeneous condensation technique in gas media. Well defined and charged Ag NPs were separated based on their sizes and were collected on quartz substrates. Thin films consisting of monodispersed Ag NPs with size ranging from 35 to 120 nm were prepared by varying an applied electric field during the fabrication process. Scanning electron microscope results showed that the samples have uniform size distribution. Coherent oscillations of conduction band electrons in gas medium induced by electromagnetic field and coupling of all similar plasmon resonances due to uniform Ag NPs size produced unique and interesting optical properties. Narrow extinction widths (∼41 to ∼69 nm) were observed compared to the width of polydispersed Ag sample. The ability to prepare samples in gas media and tune the plasmon resonance by merely varying an electric field during fabrication makes the method simple, fast, and highly economical. [ABSTRACT FROM AUTHOR]

Highlights: [•] Micrometer-sized porous carbon spheres were prepared by hydrothermal and polymer carbonization method. [•] The porous carbon spheres were excellent matrix for immobilizing nobel metal nanoparticles. [•] The obtained Au/C catalysts possess higher catalytic activity toward the reduction of 4-nitrophenol. [•] The activity factor κ of Au_5/C is 28.46s−1 g−1. [ABSTRACT FROM AUTHOR]

Abstract: Monosized macroporous poly(glycidyl methacrylate) (PGMA) microspheres that were 9.3μm in size were synthesized by multistep swelling polymerization using a modified Ugelstad technique. The PGMA microspheres and their hydrolyzed analogs derived from poly(2,3-dihydroxypropyl methacrylate) (PDHPMA) were coated by silanization with tetraethoxysilane (TEOS) and (3-aminopropyl)triethoxysilane (APTES), respectively. The particles were characterized by elemental and thermogravimetric (TGA) analysis, scanning and transmission electron microscopy (SEM and TEM) coupled with an energy dispersive X-ray analysis (EDAX) and FT-IR spectroscopy to determine the SiO2 content, morphology, particle size, polydispersity and structure. These types of particles are expected to have improved biocompatibility relative to their starting polymers. [Copyright &y& Elsevier]

Abstract: Highly crystalline single phase spherical and monodisperse cobalt ferrite (CoFe2O4) nanoparticles (NPs) with uniform shape and size distribution have been synthesized by one pot-rapid sonochemical method. The effect of different solvents, such as aqueous, alcoholic, and a mix of water/ethanol in 1:1 volume ratio on the shape, size, and crystalline structure of CoFe2O4 NPs were studied using X-ray diffraction, transmission electron microscopy, energy dispersive spectroscopy and Fourier transform infrared spectroscopy. The size of CoFe2O4 nanoparticle was controlled in the range from 20 to 110nm based on the solvent medium used in the synthesis process. Furthermore, the evolution from spherical to cubic morphology of cobalt ferrite NPs is achieved by simply changing the solvent medium from aqueous to alcoholic medium. The magnetic properties of all the synthesized CoFe2O4 NPs were studied by vibrating sample magnetometer (VSM) at room temperature. The magnetization value was found to be particle size dependent, and high magnetization (Ms) of 92.5emu/g was obtained for the CoFe2O4 NPs sample synthesized in a mixed solution of water and ethanol. A possible reaction mechanism for the formation of cobalt ferrite NPs by the sonochemical technique was discussed. The facile method adopted in our study appears to be a promising route for synthesis of highly crystalline nanoparticles within short times and without the need for using any calcination process. [Copyright &y& Elsevier]

[Display omitted] Most previous numerical studies of inhalation drug delivery used monodisperse aerosols or quantified deposition as the ratio of deposited particle number over the total number of released particles (i.e., count-based). These practices are reasonable when the aerosols have a sufficiently narrow size range. However, spray droplets from metered-dose inhalers (MDIs) are often polydisperse with a wide size range, so using monodisperse aerosols and/or count-based deposition quantification may lead to significant errors. The objective of this study was to develop a mass-based dosimetry method and evaluate its performance in lung delivery in a mouth-lung (G9) geometry with an albuterol-CFC inhaler. The conventional practices (monodisperse and polydisperse-count-based) were also simulated for comparison purposes. The MDI actuation in the open space was studied using both high-speed imaging and LES-Lagrangian simulations. Experimentally measured spray velocities and size distribution were implemented in the computational model as boundary conditions. Good agreement was achieved between recorded and simulated spray plume evolution spatially and temporally. The polydisperse-mass-based predictions of MDI doses compared favorably with the measurements in all three regions considered (device, mouth-throat, and lung). Significant errors in MDI regional deposition were predicted using the monodisperse and count-based methods. The new polydisperse-mass-based method also predicted local deposition hot spots that were one order of magnitude higher in intensity than the two conventional methods. The results of this study highlighted that a presentative polydisperse size distribution and appropriate deposition quantification method should be applied to reliably predict the MDI drug delivery in the human respiratory tract. [ABSTRACT FROM AUTHOR]

Abstract: A facile way towards high rate and long lifespan anode materials based on SnO2 and commercial multiwalled carbon nanotubes (MWCNTs) is readily achieved through a combination of activation and hydrothermal treatment. The former endows the MWCNTs with abundant hydrophilic radicals, while the latter guarantees intimate connection between SnO2 and MWCNTs; eventually, monodisperse SnO2 nanocrystals ca. 3nm are firmly anchored on the MWCNTs without agglomeration. When used for lithium ion batteries (LIBs) anodes, the hybrid composite exhibits excellent cycling capability with high reversible capacity about 700 mAh g−1 (based on total weight of the composite) for 150 cycles at 0.1 A g−1 superior to both components involved. Besides large rates of 5 A g−1 with recoverable initial reversible capacity, it also last for more than 1000 cycles with little capacity decay, outperforming most SnO2 based carbon nanotubes composites (SnO2/CNTs) so far. Insights into the electrochemical processes reveal the hybrid composite exhibits enhanced redox capacitance and interfacial capacitance in comparison with SnO2 nanocrystals which indicate the perfect interfaces and robust structure of the hybrid composite. [Copyright &y& Elsevier]

The growth of surfactant-coated nanocrystals is examined theoretically. A new single-particle growth rate is derived that explicitly models monomer diffusion through the layer of surfactant molecules, different from diffusion through bulk solution. From the single-particle growth rate, new theories for Ostwald ripening and size focusing are developed. Long surfactant molecules can strongly affect the dynamics of both growth regimes, depending on the mobility of monomers through the surfactant layer. It is implied that size focusing of nanocrystals that are coated with a well-chosen surfactant species can (in the maximal limit) be made much more monodisperse than the equivalent nanocrystals that are bare. This new maximal limit of size focusing could permit new optimized syntheses of monodisperse nanocrystals through the choice of appropriate surfactant molecules. [ABSTRACT FROM AUTHOR]

Abstract: The performance of lithium manganese phosphate as a lithium-ion battery cathode material is improved by collective and cooperative strategies including Fe substitution, carbon coating, and the assembly of carbon-coated LiMn1−x Fe x PO4 nanocrystals into a highly dense packing of monodisperse microboxes. These strategies are implemented experimentally by a facile and scalable synthesis method. The dense packing allows the conductive carbon coating to be interconnected into a continuous three-dimensional network for electron conduction. The porosity in the packed structure forms the complementary network for Li+ transport in the electrolyte. The primary particles are nanosized and Fe-substituted to improve the effectiveness of Li+ insertion and extraction reactions in the solid phase. The reduction of transport resistance external and internal to the nanocrystals yields a Li storage host with good rate performance (116 mAh g−1 at 5 C discharge rate where C = 170 mA g−1) and cycle stability (95% retention of initial capacity in 50 cycles). Electrochemical impedance spectroscopy and morphology examination of the cycled microboxes reveal a robust packed structure with stable surfaces. [Copyright &y& Elsevier]

Abstract: A previously proposed method of soap-free emulsion polymerization employing an amphoteric initiator, 2,2′-azobis[N-(2-carboxyethyl)-2-methylpropionamidine] (VA-057), was extended to synthesize micron-sized, monodisperse polystyrene (PSt) particles at low impurity levels. Initial pH values of solutions in which anionic PSt particles were formed were adjusted between neutral pH and 8.9 with a tiny amount of strong base such as NaOH to constitute a low-impurity polymerization system. Micron-sized polymer particles with a narrow size distribution were obtained in a pH range of 8.1–8.9. Different strong bases of KOH, Ca(OH)2 and tetramethylammonium hydroxide were also added to examine electrostatic interaction between PSt particles formed in the low-impurity system, indicating that surface charge density of PSt particles is an important factor to determine size distributions of PSt particles formed. Polymerizations at high styrene concentrations and an appropriate VA-057 concentration succeeded in preparation of highly pure, monodisperse PSt particles with an average size of 1.86 μm. [Copyright &y& Elsevier]

Highlights: [•] Highly stable dispersion of monodisperse Ag nanoparticles (1–2nm) was obtained. [•] Poly-amino compounds were used as effective stabilizing agent in nonaqueous medium. [•] The robust one-step route is simple and highly reproducible. [ABSTRACT FROM AUTHOR]

A facile approach was used for synthesize size-controlled monodisperse magnetite (FeO) nanoparticles. In this method, precursors were obtained only using iron (III) chloride though a simple non-alkoxide sol-gel method. Meanwhile, this operation is without the need for inert gas atmosphere and refluxing conditions and without the strict control of high temperature and pressure. The phase structures, morphologies, particle sizes and magnetic properties of FeO nanoparticles were characterized by X-ray diffraction, transmission electron diffraction, fourier-transform infrared spectroscopy, near-edge X-ray absorption fine structure and vibrating sample magnetometer. Although this approach is a small modification to other methods, the synthetic pathway includes the advantages of several other methods. In addition, this method may offer a feasible strategy for those reaction which need more moderate reaction conditions. [ABSTRACT FROM AUTHOR]

Preparation of gold nanoparticles with a narrow size distribution has enormous importance in nanotechnology. Methanobactin (Mb) is a copper-binding small peptide that appears to function as an agent for copper sequestration and uptake in methanotrophs. Mb can also bind and catalytically reduce Au (III) to Au (0). In this study, we demonstrate a facile Mb-mediated one-step synthetic route to prepare monodispersed gold nanoparticles. Continuous reduction of Au (III) by Mb can be achieved by using hydroquinone as the reducing agent. The gold nanoparticles have been characterized by UV-visible spectroscopy. The formation and the surface plasmon resonance properties of the gold nanoparticles are highly dependent on the ratio of Au (III) to Mb in solution. X-ray photoelectron spectroscopy (XPS), fluorescence spectra and Fourier transform-infrared spectroscopy (FT-IR) spectra suggest that Mb molecules catalytically reduce Au (III) to Au (0) with the concomitant production of gold nanoparticles, and then, Mb statically adsorbed onto the surface of gold nanoparticles to form an Mb-gold nanoparticles assembly. This avoids secondary nucleation. The formed gold nanoparticles have been demonstrated to be monodispersed and uniform by transmission electron microscopy (TEM) images. Analysis of these particles shows an average size of 14.9 nm with a standard deviation of 1.1 nm. The gold nanoparticles are extremely stable and can resist aggregation, even after several months. [ABSTRACT FROM AUTHOR]

Highlights: [•] Monodisperse Fe3O4@BSA core–shell nanoparticles were synthetized. [•] Fe3O4@BSA nanoparticles were spherical with the diameter of about 35nm. [•] The Fe3O4@BSA core–shell nanoparticles were superparamagnetic. [•] The content of BSA in Fe3O4@BSA was improved by adjusting reaction conditions. [ABSTRACT FROM AUTHOR]

Abstract: Monodisperse spinel CoFe2O4 nanoparticles have been synthesized through the solvothermal-assisted phase transfer method using aqueous soluble metal salts as starting materials and sodium oleate (SO) as the phase-transfer agent. The as-synthesized nanoparticles were characterized by X-ray diffraction, transmission electron microscopy, infrared spectroscopy, vibrating sample magnetometry, ultraviolet and visible spectrophotometry and Mössbauer spectrum. The results revealed that the as-obtained nanoparticles have a cubic spinel structure and an average diameter of 2–6nm. It was found that SO played an important role during the transfer of the hydrophilic inorganic precursor from aqueous phase to the organic phase. On the basis of the experimental results, a possible mechanism for the formation of the nanoparticles was proposed. Surface functionalization of the as-prepared nanoparticles was conducted to render the hydrophobic nanoparticles water-soluble, which makes the nanoparticles suitable for catalytic applications. The nanoparticles showed catalytic activity in the oxidation of methylene blue with H2O2 as an oxidizing agent. [Copyright &y& Elsevier]

Seeded emulsion polymerization and agglomerating method were well-known techniques for the production of polymeric latexes with large particle size and high solid content. Obtaining latexes with monodisperse and particle size above 300 nm scale, however, was time-consuming and difficult by means of these methods. Here, stable, monodisperse latexes with the controlled particle diameter (55-650 nm) and high solid content (60 wt%) were synthesized via one-step in batch emulsion polymerization. Experimental investigations show that the particle size increased with decreasing emulsifier concentrations and increasing monomer/water ratios or electrolyte concentrations. The latex particle coagulation was considered as the dominant particle formation and growth method, which could be proved by the evolutions of particle number as well as dimension against conversion. Latex particle coagulation occurred if the particle surface covered ratio dropped between the critical surface covered ratio ( θ = 0.59) and the lowermost surface covered ratio ( θ = 0.38). In addition, θ and θ were increased with electrolyte concentrations. [ABSTRACT FROM AUTHOR]

Monodisperse microsphere has drawn more and more attention in the past two decades. In order to synthesize it, an efficient procedure was employed by combining dispersion and seeding polymerizations together. The polymerization can be divided into two processes: nucleation and growth. Monodisperse polystyrene seed colloids with a diameter of 2 μm were synthesized in the nucleation process using dispersion polymerization, and then the seed colloids were swollen by monomer and further polymerized in the growth process. Finally, monodisperse polymer microspheres with an average diameter of 10 μm were obtained. [ABSTRACT FROM AUTHOR]

Abstract: Calcium phosphates (CaPs) are widely used as bone graft substitutes but are inherently brittle, hence restricting their use to mechanically protected environments. Combining them with a tough polymer matrix could potentially lead to a composite with load-bearing properties. However, the highest mechanical properties can only be achieved if the CaP particles possess very precise features: they should be uniform in size and shape, non-agglomerated, elongated and thin. The aim of the present study therefore was to assess a novel method to produce such particles. This involved the precipitation of CaP particles in ethylene glycol at moderate temperatures (90–170 °C) and the variation of different reaction parameters (temperature, concentration, pH, etc) to study their influence on particle composition, size, shape and dispersion was studied. As a result, two main CaP phases were obtained as well-dispersed and highly uniform platelets in the form of: (i) β-tricalcium phosphate (β-TCP) hexagonal prisms and (ii) monetite (DCP) flat parallelepipeds. The size dispersion was the narrowest for β-TCP (standard deviation/mean < 5%) whereas the aspect ratio was the highest for DCP (up to 25). In both cases, the thickness of the platelets was below 300 nm which should be ideal for the synthesis of strong CaP-based composites. [Copyright &y& Elsevier]

A series of raspberry-like magnetic-hollow silica nanospheres were successfully synthesized via the sol-gel process, which was based on the principle of the electrostatic interaction between negatively charged silica and positively charged polystyrene. The FeO@SiO particles as the outer shell were compactly assembled on the surface of PS, and then magnetic-hollow nanospheres were obtained by calcination. Different synthesis conditions including the amount of NHOH, TEOS, FeO, and the adding time of PS were systematically investigated to discuss the influence of these conditions on the morphology and structure. The prepared magnetic-hollow nanospheres were systematically characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), fourier transform infrared spectrometry, energy-dispersive X-ray analysis, thermogravimetric analysis and nitrogen adsorption-desorption measurement. SEM and TEM images exhibited that the obtained samples with the perfect spherical profile and large cavities structure were well monodisperse and uniform under the optimized condition. Zeta-potential analysis was employed to make clear the formation mechanism of raspberry-like PS@FeO@SiO composite nanosphere. Moreover, the drug release of ibuprofen experiment results demonstrated that the magnetic-hollow nanospheres could be used as a drug carrier to slowly release and deliver drugs. [ABSTRACT FROM AUTHOR]

This study reports the synthesis and characterization of composite nitrogen and fluorine co-doped titanium dioxide (NF-TiO) for the removal of contaminants of concern in wastewater under visible and solar light. Monodisperse anatase TiO nanoparticles of different sizes and Evonik P25 were assembled to immobilized NF-TiO by direct incorporation into the sol-gel or by the layer-by-layer technique. The composite films were characterized with X-ray diffraction, high-resolution transmission electron microscopy, environmental scanning electron microscopy, and porosimetry analysis. The photocatalytic degradation of atrazine, carbamazepine, and caffeine was evaluated in a synthetic water solution and in an effluent from a hybrid biological concentrator reactor (BCR). Minor aggregation and improved distribution of monodisperse titania particles was obtained with NF-TiO-monodisperse (10 and 50 nm) from the layer-by-layer technique than with NF-TiO + monodisperse TiO (300 nm) directly incorporated into the sol. The photocatalysts synthesized with the layer-by-layer method achieved significantly higher degradation rates in contrast with NF-TiO-monodisperse titania (300 nm) and slightly faster values when compared with NF-TiO-P25. Using NF-TiO layer-by-layer with monodisperse TiO (50 nm) under solar light irradiation, the respective degradation rates in synthetic water and BCR effluent were 14.6 and 9.5 × 10 min for caffeine, 12.5 and 9.0 × 10 min for carbamazepine, and 10.9 and 5.8 × 10 min for atrazine. These results suggest that the layer-by-layer technique is a promising method for the synthesis of composite TiO-based films compared to the direct addition of nanoparticles into the sol. [ABSTRACT FROM AUTHOR]

A novel approach to the synthesis of highly monodisperse quantum dot-loaded polymer beads by combining impregnation and precipitation techniques was reported. The monodisperse poly(glycidyl methacrylate) (PGMA) beads were first synthesized by dispersion polymerization. Then, the PGMA beads were chemically modified to generate carboxyl groups, and impregnation of cadmium ions (Cd2+) inside the beads. Subsequently, the cadmium ions were reacted with thioacetamide to form cadmium sulfide (CdS) quantum dots within the polymer beads. The morphology, structure, and properties of CdS quantum dot-loaded polymer beads were studied by field emission scanning electron microscope (SEM), transmission electron microscope, fluorescence spectrophotometer, fluorescence microscope, Fourier transform infrared spectroscopy, powder X-ray diffraction, and thermogravimetric analysis. The results indicated that the CdS quantum dot-loaded polymer beads had an average size of 1.4 μm, and were highly monodisperse. More interestingly, the CdS quantum dots distributed evenly within the polymer beads, which provide very strong fluorescence intensity. The existence of carboxyl groups on the quantum dot-loaded polymer beads was measured quantitatively, and was found to be 0.2 mmol/g. These CdS quantum dot-loaded polymer beads involving functional carboxyl groups would have potential applications in biological immunoassay and photoelectronic fields. © 2013 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013 [ABSTRACT FROM AUTHOR]

Phase-pure nano-LiFePO was successfully fabricated under hydrothermal condition at different temperatures. We found that the obtained particle morphologies and sizes were temperature-dependent. Compared with other samples, the as-received LiFePO synthesized at 200°C for 3 h presented monodisperse state. Moreover, this product possessed excellent electrochemical performance and cycling stability after annealing at 700°C for 1 h with glucose as carbon source. [ABSTRACT FROM AUTHOR]

The aim of this study was to investigate the effect of operating parameters such as liquid flow rate, gas inlet pressure, and capillary diameter as well as the influence of the physical properties of the liquid, in particular viscosity, on the generation of monodisperse microbubbles in a circular cross section T-junction device. Aqueous glycerol solutions with viscosities ranging from 1- to 100 mPa s were used in the experiments. The bubble diameter generated was studied for systematically varied combinations of gas inlet pressure, liquid flow rate, and liquid viscosity with a fixed capillary inner diameter of 150 μm for the liquid and gas inlet channels as well as the outlet channel. In addition, the effect of channel geometry on bubble size was studied using capillaries with inner diameters of first 100 and then 200 μm. In all the experiments the distance between the coaxial capillaries at the junction was set to be 200 μm. All the microbubbles produced in this study were highly monodisperse (polydispersity index <1 %) and it was found, as expected, that bubble formation and size were influenced by the ratio of liquid to gas flow rate, capillary size, and liquid viscosity. The experimental data were then compared with empirical scaling laws derived for rectangular cross-section junctions. In contrast with these previous studies, which have found bubble size to be dependent on either the flow rate ratio (the squeezing regime) or capillary number (the dripping regime), in this experimental study bubble size was found to depend on both capillary number and flow ratio. [ABSTRACT FROM AUTHOR]

The surface of individual, relatively dispersed FeO nanospheres is coated with a thiol-terminated silane, then the thiol on the FeO particles' surfaces treats with nano-Ag colloidal solution to form Ag-modified FeO nanoparticles. Eventually, a solid shell of Ag is capped onto the Ag-modified FeO nanoparticles by reducing aliquots of AgNO solution using NaBH as a reducing agent. The as-prepared FeO-core@Ag-shell nanoeggs, which are uniform in size, highly monodisperse, stable against aggregation and have high magnetization, were depended on thin shell of the attached nano-Ag, the size of FeO nanoparticles, the volume of thiol-terminated silane as well as the ultrasonication. The FeO-core@Ag-shell nanoeggs are proposed to detect fingermarks on different surface, with which the fingermarks can be viewed directly, due to the clear ridge detail. [ABSTRACT FROM AUTHOR]

Abstract: Highly stable dispersion of silver nanoparticles (Ag NPs) (1–2nm in diameter) having low size distribution was synthesized using a straightforward one-step synthesis method. Tetraethylenepentamine (TEPA), a kind of aliphatic amine, was utilized as stabilizing agent to prevent the aggregation of Ag NPs in nonaqueous medium. The successful formation of TEPA-stabilized Ag NPs was demonstrated by ultraviolet–visible spectroscopy (UV–vis), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and Fourier-transform infrared spectroscopy (FTIR). The mechanism of TEPA on the stabilization of Ag NPs is also discussed. This facile one-step synthesis route may provide a new perspective for creating other nanoparticles that have potential application in various nanotechnology fields. [Copyright &y& Elsevier]

Abstract: Synthetic conditions to produce highly crystalline monodisperse ETS-10 crystals with the length along the [110] direction (L [110]) between 17 and 55μm and the length along the [001] direction between 15 and 80μm were developed. This was achieved by varying the amounts of KF in the gel consisting of Na2SiO3, titanium isopropoxide, HCl, NaCl, KF, and H2O. The UV–vis spectra of the ETS-10 crystals revealed that the absorption band red-shifts with increasing L [110]. The plot of band gap energies (E g values) with respect to L [110] values revealed a progressively decaying relationship. The mixing of the newly observed data set with that reported previously from the ETS-10 crystals with L [110] between 0.3 and 20μm gave a smooth exponential decay relationship, E g =0.2578 exp(−L [110]/13.751)+3.7667, as if they came from a single data set. Analysis shows that the quantum confinement effect still operates in TiO3 2− quantum wires with the estimated length of 368nm. The μ xy and μ z values are 15.2 and 0.0006me, respectively. A monotonous quadratic relationship exists between L [110] and l. Thus the length of the titanate quantum wire increases more than the degree the crystal size increases, indicating that the degree of defect per unit volume decreases as the crystal size increases. [Copyright &y& Elsevier]

Abstract: Factors for controlling sizes of silica particles formed in the hydrolysis and condensation of silicon alkoxides were examined in batch and semi-batch processes with our model previously proposed. Particle sizes in the particle formation were simulated for buffer systems to reduce time-variation in pH. Effectiveness of the buffer system to suppress time-variation in ionic strength was experimentally verified in a silicon alkoxide concentration range of 0.01–0.1M. Comparison of experimental particle sizes with calculated ones showed that the addition of electrolytes slightly decreased surface potential of silica particles in both batch and semi-batch processes, and the surface potential values estimated for the semi-batch process were lower than that for batch process. In simulation of the number of particles formed in the processes, the particle number had strong dependences on surface potential and Debye–Hückel parameter. The simulated number of particles formed in semi-batch process was smaller than that in batch process under the same surface potential and Debye–Hückel parameter. The combination of the low surface potential and the small number of particles revealed that the semi-batch process was suitable for producing a small number of particles, which provides enlargement of size range of silica particles formed in the method. [Copyright &y& Elsevier]

Highly monodisperse CdS nanospheres capped with allyl thiourea were synthesised via a facile hydrothermal method without any surfactant. The products were characterised by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, photoluminescence and Fourier transform infrared spectra. The results show that CdS nanospheres have the diameters of about 300 nm and are composed of nanoplates. The reaction parameters, such as the concentration of the reagent, the ratio of sulphide to cadmium source and the cadmium salt type that affected the CdS morphology, were investigated systematically. Based on the experiments, the possible formation mechanism for the nanospheres is ascribed to anisotropic growth of the nanoparticles and self-assembly caused by the lowest surface tension. The photoluminescence spectrum of the nanospheres shows about 60 nm blue shift compared with that of bulk CdS. [ABSTRACT FROM AUTHOR]

Abstract: The temperature sensitive SiO2/PNIPAAm composite microspheres were designed and successfully synthesized. The influences of monomer concentration, reaction time, reaction temperature and initiator amount on water contact angel of the prepared microspheres were investigated. The structure, morphology, and surface composition were characterized by Fourier Transform Infrared Spectroscopy (FTIR) and Transmission Electron Microscopy (TEM), X-ray Photoelectron Spectroscopy (XPS). The temperature sensitive properties in aqueous solution were studied by water contact angle measurement instrument and dynamic light scatter (DLS). The results show that the low critical solution temperature (LCST) of SiO2/PNIPAAm composites is around 304K and the particle is monodisperse microsphere. [Copyright &y& Elsevier]

Lead halide perovskite (LHP) quantum dots (QDs), with their bright and narrow emission, are promising candidates for LEDs, lasers, and quantum light sources. However, current methods to synthesize monodisperse CsPb(Cl:Br) 3 and CsPbCl 3 QDs exhibiting multiple sharp absorption resonances are not as well developed compared to CsPbBr 3 . Furthermore, both quantum confinement and the halide ratio in CsPb(Cl:Br) 3 QDs strongly influence the bandgap, making it impossible to optically determine their size. In this work, monodisperse spheroidal CsPb(Cl:Br) 3 QDs are synthesized in the 4-10 nm range, at any Cl:Br ratio, with up to five excitonic absorption transitions. Furthermore, in situ spectroscopy was used to cross-correlate the size and composition of these QDs directly to the energy of the first two excitonic absorption transitions. This work therefore provides not only a method for monodisperse CsPb(Cl:Br) 3 QDs but also a protocol to determine their size, concentration, and halide ratio, circumventing conventional expensive and time-consuming techniques.

Sequence-defined synthetic oligomers and polymers provide unprecedented opportunities for polymer chemists to finely control properties such as chain folding, self-assembly, and optoelectronic performance of materials. However, absolute control over both chain-length and monomer sequence has been a long-standing "grand challenge" for decades. Herein, we report a novel strategy to synthesize monodisperse sequence-defined conjugated oligomers in a homogeneous manner by temperature cycling, thereby achieving single-monomer precision in conjugated polyheterocycles. A series of sequence-defined oligomers with up to twelve repeating units, four different monomers, and various sequences were successfully synthesized. Monomer sequence was also proved to affect optical properties. We believe this strategy not only exhibits general applicability to the synthesis of group 16 conjugated oligomers and polymers, but also has far-reaching potential for other polymer systems., (© 2022 Wiley-VCH GmbH.)

Abstract: Highly monodisperse methyl-functionalized, vinyl-functionalized, and thiol-functionalized polysilsesquioxane spheres (MPSQ, VPSQ, and MPPSQ spheres) have been successfully prepared through a one-pot emulsion approach with one organosilane as sole precursor in aqueous medium. The morphology, size distribution, and chemical structure were characterized by SEM, DLS, FT-IR, solid NMR, XRD, etc. The thermodecomposition and hydrophobicity of these spheres were investigated with TGA and water contact angle measurement. Our research turns out that the organofunctional groups play a key role in thermostability and hydrophobicity of polysilsesquioxane spheres, MPSQ, and VPSQ spheres possess better thermostability than MPPSQ spheres, the order of hydrophobicity is as follows: MPSQ>VPSQ>MPPSQ. Cotton fabrics can become superhydrophobic when treated with methyl- or vinyl-functional silica spheres. [Copyright &y& Elsevier]

Abstract: The main obstacle of the electrospray method; especially cone-jet mode, to apply many industry fields is low throughput of electrospray method. One of the functioning modes of electrospray labeled multi-jet mode is alternative mode to solve to problem and to achieve high throughput. Because of the positional instability and polydispersity of generated droplet size, multi-jet mode is rarely studied to compare with cone-jet mode. To eliminate this shortcoming, we exploited free surface electrospraying system using arrayed hole at the side of the nozzle. For evaluation of the nozzle system, the electric current and size distribution of electrosprayed droplets were measured under various experimental conditions. The electric current in the multi-jet mode obeyed the same power law as the single cone-jet mode as a function of flow rate. In particular, both modes produced almost the same size distribution of droplets for a given average jet flow rate. [Copyright &y& Elsevier]

Abstract: Monodisperse FeWO4 nanoparticles with specific spindle-like morphology have been synthesized in the presence of citric acid through hydrothermal process. In the synthesis route, citric acid played four roles such as the reducing agent, chelating regents, structure-directing agent and stabilizing agents. In addition, the morphology of FeWO4 was dramatically tuned by the pH value of the precursor medium. The optical properties of FeWO4 were investigated with UV–Vis spectra and photoluminescence spectroscopy. The photocatalytic experiments demonstrated that the decomposition efficiency of the monodisperse spindle-like FeWO4 nanoparticles is 74% after 30min of UV irradiation, which displayed remarkable enhanced photodegradation activity compared with ordinary FeWO4 sample (57%) and normal TiO2 photocatalysts P-25 (56%). [Copyright &y& Elsevier]

Monodisperse FePt nanoparticles with average size of 2.4 nm were successfully synthesized via chemical co-reduction of iron acetylacetonate, Fe(acac), and platinum acetylacetonate, Pt(acac), by 1,2-hexadecanediol as a reducing agent and oleic acid and oleyl amine as surfactant. Then using the seed mediated growth process smaller sized FePt nanoparticles are used as seeds for the growth of larger sized FePt particles and there is no specific limitation to achieve upper size range by this method. In this work, we could synthesize FePt nanoparticles up to 4.0 nm. Monodispersity with relatively narrow size distribution and having the same elemental composition with the atomic percentage of FePt ( x = 63) are the main advantages of this method. As-made FePt nanoparticles have the chemical disordered face centered cubic structure with superparamagnetic behavior at room temperature. After annealing these particles become ferromagnetic with high magnetocrystalline anisotropy and their coercivity increases with increasing particle sizes and reaches a maximum value of 5,200 Oe for size of 46.5 nm [ABSTRACT FROM AUTHOR]

The emulsifier-free emulsion polymerization of N-hydroxymethyl acrylamide (NMA), methyl methacrylate (MMA) and styrene (St) was successfully carried out under microwave irradiation, and monodisperse polymeric microspheres were prepared. The experimental results show that the emulsifier-free emulsion polymerization under microwave irradiation has more rapid reaction rate, higher conversion and shorter induction time than the copolymerization with conventional heating. The apparent activation energies are 61.04 and 83.75 kJ/mol, respectively; the microspheres have spherical morphology, and the microspheres prepared by emulsifier-free emulsion polymerization under microwave irradiation are smaller, more uniform than those obtained with conventional heating. [ABSTRACT FROM AUTHOR]

Abstract: Isotropic scattering coefficient measurements were made of monodisperse polystyrene lattices of two different diameters of 144nm and 223nm and at volume fractions ranging from 0.15 to 0.22, using frequency domain photon migration measurements at wavelengths of 660, 685, 785 and 828nm. The isotropic scattering coefficient measurements were shown to be sensitive to the changing ionic strength (0.5–4mM, NaCl equiv.) of the dispersions exhibiting hindered scattering owing to structure at the lowest ionic strength values. Monte Carlo simulations and numerical solution of the Ornstein Zernike equations were used to compute isotropic scattering coefficients for comparison to measured values. The interaction potential was modeled as a hard sphere Yukawa potential and the Hypernetted Chain closure was used to solve the OZ equation. Effective particle charges were found after renormalization of the bare particle charge and used to predict the isotropic scattering coefficient. The model data were found to follow similar trends as experimental measurements. The refractive index of the particles has found to be an important factor for predicting experimental isotropic scattering coefficient values. [Copyright &y& Elsevier]

This contribution describes a simple, aerosol-based method for fabricating monodisperse particles containing mixtures of poly(lactide- co-glycolic acid) [PLGA], protamine sulfate (Prot), and poly( l-lysine) [PLL] as nanocarriers for gene transfection. Aqueous solutions of PLGA, Prot, and PLL were collison-atomized, and the resulting aerosolized droplets were dried 'on the fly' to form solid particles, which then were electrostatically size-classified into 50, 100, and 200 nm mobility diameter samples. Measurements of cell viability and transfection reveal that the fabricated nanocarriers have a lower cytotoxicity (>85% in cell viability) and a higher transfection efficiency [>8.7 × 105 in relative light units (RLU) mg−1] than does 25 kDa polyethyleneimine (≈50% and 6.8 × 105 RLU mg−1). [ABSTRACT FROM AUTHOR]

Herein, we report a facile surfactant-assisted solvothermal synthetic method to prepare nearly monodisperse spherical CeO2 nanocrystals. A good control of the size of CeO2 nanocrystals in the range of 100-500 nm was achieved by simply varying the synthetic parameters such as reaction time, volume ratio of ethanol to water ( R), molar ratio of PVP, and concentration of Ce(NO3)3⋅6 H2O in solution. A possible mechanism for the growth of spherical CeO2 nanocrystals is proposed. The obtained CeO2 nanocrystals with a surface area of up to 47 m2g−1 were then employed as a catalyst support. By loading Au-Pd nanoparticles (about 3 wt. %) onto the CeO2 support, an Au-Pd/CeO2 catalyst was prepared that exhibited high catalytic activity for HCHO oxidation. At the low temperature of 50 °C, the percentage of HCHO conversion was 100 %, suggesting potential applications in preferential oxidation and other catalytic reactions. These Au-Pd/CeO2 catalysts may also find applications in indoor formaldehyde decontamination and industrial catalysis. The facile solvothermal method can be extended to the preparation of other metal oxide nanocrystals and provides guidance for size- and morphology-controlled synthesis. [ABSTRACT FROM AUTHOR]