Narrow Particle Size Distribution Research Articles

Unleashing the Influence of High-Throughput Flow Process Optimization on Luminescent Behavior of Engineered ZnO Quantum Dots

Engineered ZnO quantum dots (E-QDs) are sought-after nanostructures in healthcare and optoelectronic industries, necessitating a paradigm shift toward high-throughput continuous flow platforms, the crux to whose successful design and performance lies in comprehending the nucleation-growth kinetics, defect engineering, and reaction dynamics. This work investigates the synergistic interplay of enhanced hydrodynamics and heat–mass transfer in the helical coil reactor, fostering rapid nucleation-growth-driven E-QDs fabrication. We integrated computational fluid dynamic modeling, and comprehensive experimentation for producing E-QDs with record-high photoluminescence quantum yield (PLQY) (∼89% in the yellow-green spectrum) by carefully creating oxygen vacancies via a novel reproducible protocol. Dean vortices formed due to the helical geometry facilitated ultrafast mixing and accelerated reaction kinetics, yielding colloidally stable E-QDs in gram-scales [ζ = −39.7 mV, polydispersity index (PDI) ∼0.22] with a narrow particle size distribution (average particle size ∼4.5 nm). Contrastingly, the conventional batch route produced less stable E-QDs with ζ value of −15.3 mV, PDI ∼0.41, and diminished PLQY (∼40%) because of inadequate process control, batch-to-batch variability due to poor mixing, and heat transfer. The simple, economical, in-house-fabricated flow reactor manifested ∼90% increment in yield and reduced product cost. Thus, this research demonstrated the benefits of simulation-driven process engineering and reactor design in catalyzing QDs-based innovations.

Exploring the Potent Combination of Quercetin-Boronic Acid, Epalrestat, and Urea Containing Nanoethosomal Keratolytic Gel for the Treatment of Diabetic Neuropathic Pain: In Vitro and In Vivo Studies.

Transdermal penetration of therapeutic moieties from topical dosage forms always remains a challenge due to the presence of permeation impeding keratin which should be addressed. The purpose of the study was to formulate quercetin and 4-formyl phenyl boronic acid (QB complex) used for the preparation of nanoethosomal keratolytic gel (EF3-G). The QB complex was confirmed by Fourier transform infrared spectroscopy while skin permeation, viscosity, and epalrestat entrapment efficiency were used for the optimization of nanoethosomal gel. The keratolytic effect of the proposed nanoethosomal gel with urea (QB + EPL + U) was calculated in rat and snake skin. The spherical shape of nanoethosomes was confirmed by scanning electron microscopy. According to the findings of stability studies, viscosity decreases as temperature increases, proving their thermal stability. The negative charge of optimized EF3 with 0.7 PDI proved narrow particle size distribution with homogeneity. Optimized EF3 showed two folds increase of epalrestat permeation in highly keratinized snake skin as compared to rats' skin after 24 h. Antioxidant behaviors of EF3 (QB) > QB complex > quercetin > ascorbic acid proved reduction of oxidative stress in DPPH reduction analysis. Interestingly, the hot plate and cold allodynia test in the diabetic neuropathic rat model reduced 3-fold pain as compared to the diabetic control group which was further confirmed by in vivo biochemical studies even after the eight week. Conclusively, ureal keratolysis, primary dermal irritation index reduction, and improved loading of epalrestat render the nanoethosomal gel (EF3-G) ideal for the treatment of diabetic neuropathic pain.

New Approaches to the Synthesis and Stabilization of Polymer Microspheres with a Narrow Size Distribution.

This article presents the results of investigations on heterophase polymerization of vinyl monomers in the presence of organosilicon compounds of different structures. On the basis of the detailed study of the kinetic and topochemical regularities of the heterophase polymerization of vinyl monomers, the conditions for the synthesis of polymer suspensions with a narrow particle-size distribution using a one-step method have been determined.

Photo, thermal and photothermal activity of TiO2 supported Pt catalysts for plasmon-driven environmental applications

TiO2+Pt plasmonic solids with 1 wt% Pt and different TiO2 supports (anatase nanoparticles (TNP), polycrystalline nanorods (a-TNR) and single-crystal anatase nanorods (TNR)) were synthesized using the wet impregnation technique and tested as photo, thermal and photothermal catalysts in gas-solid and gas-liquid-solid reactions. Due to the different charges of the TiO2 support surfaces, Pt particles with different sizes, crystallinities and degrees of interaction with the TiO2 supports were formed during the synthesis. The heights of the Schottky barrier (SBH) were 0.38 eV for the a-TNR+Pt, 0.41 eV for the TNP+Pt, and 0.50 eV for the TNR+Pt samples, respectively. The low visible-light-triggered photocatalytic activity of the TNR+Pt catalyst toward the oxidation of water-dissolved bisphenol A (BPA) is attributed to its high SBH and active site deactivation due to the adsorption of BPA and/or BPA oxidation products. The highest photothermal catalytic H2-assisted NO2 reduction rate was expressed by the TNR+Pt catalyst. This can be ascribed to the presence of a narrow particle size distribution of small Pt particles, the absence of the Pt catalysed reduction of the TNR support at higher temperatures, and the lower rate of re-injection of “hot electrons” from the TNR support to the Pt particles.

Free radical copolymerization of β-Myrcene by suspension process

In this study, for the first time, synthesis of polymer microbeads from β-myrcene (My) and 1,4-butanediol dimethacrylate (BDDMA) by suspension copolymerization is described. Free radical copolymerization of My and BDDMA has been either photo- or thermally initiated. In both systems influence of monomer composition has been investigated by varying the ratio of My between 10 and 90 vol% in the oil phase composition. My-BDDMA based microspheres have been synthesized successfully via both thermally initiated and photoinitiated suspension copolymerization process. Particle morphology, size and distribution of the microbeads has remarkably influenced by monomer composition and initiation step of the polymerization process. Photoinitiated copolymerization has resulted in a decrease in particle size and yielded quite narrow particle size distributions compared to thermally initiated copolymerization. The average molecular weight between cross-links (Mc), and cross-linking density (ν), calculated by using the Flory-Rehner Theory, has confirmed the significant influence of monomer composition and initiation step on the cross-linking.

The effect of mechanical activation duration on the structure and physical properties of titanium slag

TiO2 is popular in modern industries, including dyestuffs, printing, and cosmetics. To convert titanium slag to TiO2 with maximum efficiency, mechanical activation is an important pretreatment step to control the particle size of the titanium slag and the subsequent leaching process. Our study used a planetary high-energy ball mill to wet the titanium slag by mechanical activation for 3, 9, and 15 h to obtain the optimized condition for particle size control of the pretreated titanium slag. The phase composition was characterized by XRD, FT-IR, and Raman spectroscopy. The main constituents of the titanium slag were determined to be rutile TiO2 and Fe3Ti3O10. Calculating the relative intensity showed that some encapsulated phases were opened because of mechanical activation. The weight and density of titanium slag in the same volume increased, resulting in significantly enhanced peaks. The results can greatly improve the efficiency of subsequent titanium dioxide production. A laser particle size analyzer and SEM characterized the mechanical activation product. The results showed that when the mechanical activation duration is 15 h, the titanium slag obtained has a small particle size and a uniform, smaller specific surface area, and narrow particle size distribution. The current report has not introduced wet grinding to pretreat titanium slag. This simple method can be effectively applied to pre-treat titanium slag raw materials.

Continuous preparation of multi-scale HMX-based energetic composite microspheres by pipe-stream technology

Continuous preparation of energetic microspheres has become a goal pursued by researchers in recent years. This paper combines the pipe control method with suspension self-assembly technology to design and build a pipe-stream control device, which was applied to prepare multi-scale HMX-based microspheres with high sphericity and narrow particle size distribution. The average particle sizes of microspheres have a significant correlation with the process parameters. The flowability, bulk density of HMX-based microspheres and mechanical properties of charges have been significantly improved (energetic microspheres vs water-suspension molding powder, ≯24.6° vs 27.0°; 0.568 g·cm−3 vs 0.489 g·cm−3; 31.6 MPa vs 13.41 MPa). The impact and friction sensitivity of HMX@F2602 microspheres with different particle sizes decreased by 111% ∼ 178% and 80%. Real-time and accurate regulation of particle size can be achieved by changing the process parameters, which has a broad application prospect.

Granulated WC-Co obtained by spray drying from aqueous suspensions

Aqueous suspensions of hard metal powders and their use are known to have significant environmental and economic advantages over the systems employed nowadays using organic solvents. The present research describes developing a novel and less harmful processing route for hard metal production. Aqueous spray drying is convenient for obtaining dried WC-Co granules without extensive agglomeration. The spray-dried powders exhibit good flowability due to their shape and relatively narrow particle size distribution. The spray-dried granules have been pressed and sintered in an industrial sintering oven under a vacuum. The characterisation of the samples has highlighted the size, morphology, and some technological properties, while the sample's metallurgical properties have been assessed for the sintered compacts. By employing the abovementioned processes, both the granules and the subsequent hard metals revealed appropriate properties with biphasic (Co-WC) sintered compacts, which prove that such a process is feasible.

Preparation of oxidized nanocellulose by using potassium dichromate

Nanocellulose derivatives are being used in a wide variety of high-quality functional applications. One of them is oxidized nanocellulose, which has been used in biomedical and pharmaceutical applications due to its biodegradable, biocompatible, hemostatic, and antibacterial properties. In this work, oxidized nanocellulose was synthesized using potassium dichromate as an oxidizing agent. The structure of oxidized nanocellulose was investigated by means of ultraviolet spectrophotometry, Fourier transform infrared spectroscopy, X-ray diffraction, atomic force microscopy, and thermogravimetric analysis. The results showed that the primary hydroxyl groups of NC were selectively oxidized to carboxyl groups and their content of 1.36 mmol/g was achieved. The appearance of a new peak (1721 cm−1) in the FTIR- spectra related to the C=O group was observed. The change of oxidized nanocellulose’s crystal index from 88.0% to 82.5% was revealed, and the sizes of the unit cells of both nanocellulose and oxidized nanocellulose were calculated. The thermal stability of oxidized nanocellulose decreased compared to nanocellulose. The oxidation process of nanocellulose leads to a change in the shape and size of particles from acicular to spherical with a narrow particle size distribution. It was shown that oxidized nanocellulose has the ability to accumulate charges on its surface.

Environmentally benign sensing platform for label free detection of Fe3+ and tobramycin using highly fluorescent carbon dots valorized from sweet potato roasting residues

A novel sustainable source with zero intended energy consumption is introduced for the first time for obtaining carbon dots (CDs). These CDs were spontaneously formed during the ordinary roasting of sweet potato (SPCDs) with a yield of 160.54 mg/kg. The obtained SPCDs exhibited high fluorescence quantum yield (53%) at 442 nm after excitation at 360 nm, narrow particle size distribution (3.54 ± 1.08 nm) and negative zeta potential (-12.2 mV). Using the obtained SPCDs, a sensitive, selective, rapid, and effortless turn off–on fluorescent sensing platform was constructed for label free detection of the non chromophoric drug, tobramycin (TOB). The proposed sensing strategy was based on the possible Fe3+ induced mixed mode static quenching/inner filter effect and fluorescence recovery through its complexation by TOB. The sensor demonstrated good performance for TOB detection with a linear range of 10.69 – 106.90 µM (5–50 µg/mL). The sensing platform was successfully applied for TOB detection in its ophthalmic solution, with good accuracy (100.39% ± 2.19) and precision (RSD, 2.18%), and can be adopted for its routine analysis without any chemical derivatization. Moreover, the developed sensor was successfully applied for TOB detection in real samples including honey and river water. Such sustainable and cost-effective carbon dots require neither special equipment nor hazardous chemicals so that it can be adopted as a source for CDs.

Preparation and characterization of superfine spherical TKX‐50 with a hollow structure by spray drying

AbstractMicro/nano energetic materials with regular morphologies exhibit high energy release efficiency, superior charge performance, and low mechanical sensitivity. Exploring dihydroxylammonium 5,5′‐bistetrazole‐1,1′‐diolate (TKX‐50) with spherical microstructures and excellent comprehensive properties is of great significance for potential applications. In this work, a kind of superfine spherical TKX‐50 was fabricated by spray drying method. The as‐prepared TKX‐50 had a narrow particle size distribution with d50=3.14 μm, high sphericity of 0.944 with hollow structure and bulk density of 1.851 g/cm3. And its formation mechanism was proposed. The results of XRD and FT‐IR demonstrated that spray drying would not change the crystal structure of TKX‐50. TG‐DSC results showed that the initial decomposition and the peak temperature of superfine spherical TKX‐50 was about 10 °C lower than raw TKX‐50, and the apparent activation energy was 4.584 kJ ⋅ mol−1 lower than raw TKX‐50, due to the dramatic change in morphology. TG‐DSC‐FTIR‐MS provided a new understanding of decomposition process of TKX‐50, and the results illustrated that the main gas products were N2, H2O, N2O, NH3, NO, NH2, CO2, and HCN. Superfine spherical TKX‐50 underwent similar decomposition path as raw TKX‐50 but stood out in its larger occupation of the first decomposition which meant a more complete decomposition and its faster rate of the whole decomposition process. More importantly, the impact sensitivity (H50) increased from 50.1 cm to 70.8 cm, and the friction sensitivity (P) decreased from 24 % to 0 %, showing improved safety performance.

Cytotoxicity Evaluation of Photosensitizer-Conjugated Hexagonal Upconverting Nanoparticles.

In this report, we synthesized hexagonal NaYF4:Yb,Er upconverting nanoparticles (UCNPs) of 171 nm in size with a narrow particle size distribution. To address their colloidal stabi-lity in aqueous media and to incorporate a photosensitizer that can produce reactive singlet oxygen (1O2) to kill tumor cells, UCNPs were conjugated with 6-bromohexanoic acid-functionalized Rose Bengal (RB) and coated with PEG-alendronate (PEG-Ale). The particles were thoroughly characterized by transmission electron microscopy, dynamic light scattering, ATR FTIR, X-ray photoelectron spectroscopy, thermogravimetric analysis, and spectrofluorometry, and 1O2 formation was detected using a 9,10-diphenylanthracene spectrophotometric probe. Cytotoxicity determination on rat mesenchymal stem cells by using the MTT assay showed that neutralization of the large positive surface charge of neat UCNPs with PEG-Ale and the bound RB sensitizer significantly reduced the concentration-dependent cytotoxicity. The presented strategy shows great potential for the use of these particles as a novel agent for the photodynamic therapy of tumors.

PH-responsive Sulfated Hyaluronic Acid Nanoparticles Targeting Tumor Cells and CAFs for the Treatment of Breast Cancer.

Tumor metastasis is a main cause of death in patients with breast cancer. The cross-talk between cancer-associated fibroblasts (CAFs) and tumor cells plays an important role in promoting tumor invasion and metastasis. It is important to develop a novel delivery system to inhibit tumor development by simultaneously targeting both CAFs and tumor cells. The main objective of this research was to prepare nanoparticles to inhibit tumor proliferation and migration by blocking the cross-talk of tumor-CAFs. Additionally, a novel "MCF- 7+NIH/3T3" mixed cell model was established to mimic the tumor microenvironment (TME). In this study, the pH-responsive nanoparticles (MIF/DOX-sul-HA NPs) based on sulfated hyaluronic acid (sul-HA) polymers were prepared for co-delivery of doxorubicin (DOX) and mifepristone (MIF). The effects of anti-proliferation and anti-metastasis of MIF/DOX-sul-HA NPs were investigated both in vitro and in vivo. The results showed that MIF/DOX-sul-HA NPs were nearly spherical in shape with narrow particle size distribution and pH-responsive drug release, and could be taken up by both MCF-7 and NIH/3T3 cells. Compared with MCF-7 cells alone, the anti-tumor effect of single DOX was weak in the "MCF-7+NIH/3T3" mixed cell model. MIF/DOX-sul-HA NPs exhibited strong effects of anti-proliferation and anti-metastasis than the free single drug. The sul-HA nanoparticles for co-delivery of DOX and MIF could be a promising combined therapy strategy for the treatment of breast cancer.

Physicochemical properties and structural evolution of synthetic substituted bioceramic in nano regime

Zinc-substituted fluorohydroxyapatite/beta-tricalcium phosphate (ZFHA/β-TCP) nanocrystals were prepared by a novel solid-state synthesis method. From Rietveld refinement of XRD patterns, no phase transformations and secondary phases were detected, and single-phase Zn2+-doped FA was observed as dopant concentration increased. A significant increase in crystallite sizes was observed after heat treatment at 900 °C. Spheroidal nanoparticles with an average particle size of 44.0 ± 6.4 nm and a narrow particle size distribution were detected by electron microscopy. 98% and 100% reductions in the number of colonies were observed for ZFHA/β-TCP against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli), respectively. A typical apatite layer was developed on the surface of the substituted structure even after 3 days of immersion in simulated body fluid (SBF).

Electrospun CaxSr1-xZrO3 fibrous membranes with modified microstructure and high-temperature stability

Zirconate fibrous membranes show promising applications in high thermal insulating areas for the high melting point, low thermal conductivity and good phase stability. To satisfy the high-temperature mechanical demands, the microstructure of zirconate fibers needs further modification to accommodate high-temperature stability. In consideration of the slow ion diffusion rate and enhanced stability of solid solution, CaxSr1-xZrO3 fibrous membranes were electrospun with molar ratio of Ca/Sr varied from 0.9 to 0.5 for the present work. The effects of strontium precursor on the pyrolysis process, phase formation and microstructure evolution were fully characterized. Modified microstructures with smaller grain size and narrow particle size distribution were achieved. Furthermore, the NIR reflectivity, thermal conductivity, and high-temperature stability were also presented. The special expansion character of fibrous membrane at high temperature would make it promising candidate to compensate the shrinkage of other oxide fibrous membrane.

A Novel Non-Metallic Photocatalyst: Phosphorus-Doped Sulfur Quantum Dots.

In this paper, a novel phosphorus-doped sulfur quantum dots (P-SQDs) material was prepared using a simple hydrothermal method. P-SQDs have a narrow particle size distribution as well as an excellent electron transfer rate and optical properties. Compositing P-SQDs with graphitic carbon nitride (g-C3N4) can be used for photocatalytic degradation of organic dyes under visible light. More active sites, a narrower band gap, and stronger photocurrent are obtained after introducing P-SQDs into g-C3N4, thus promoting its photocatalytic efficiency by as much as 3.9 times. The excellent photocatalytic activity and reusability of P-SQDs/g-C3N4 are prospective signs of its photocatalytic application under visible light.

Low Cu(II) Concentration Detection Based on Fluorescent Detector Made from Citric Acid and Urea.

Carbon quantum dots (CQD) are an advanced fluorescent material, which has attracted more and more attention in theoretical research and practical applications. To obtain stable CQDs with high fluorescence characteristics for detecting trace metal ions in water, nitrogen-doped carbon quantum dots (N-CQDs) based fluorescent sensors were synthesized by the hydrothermal method, using citric acid and urea as source. Transmission electron microscopy (TEM) images showed that the synthesized N-CQDs maintained a narrow particle size distribution bellow 10nm, and its average size was 3.07nm. Fourier transform infrared spectroscopy (FT-IR) indicated that abundant hydroxyl and carboxyl functional groups existed on N-CQDs surface, which helped N-CQDs highly disperse in water. In addition, UV-vis spectroscopy and photoluminescence demonstrated that the N-CQDs obtained a 10.27% of quantum yield (QY) with relatively high and stable fluorescence performance. As a fluorescent sensor, the N-CQDs showed a fluorescence "ON-OFF" mechanism during the Cu2+ detection, which was induced from the electrons transition in surface functional groups. The final N-CQDs exhibited a wide linear relationship between fluorescence response and concentration of Cu2+ in range of 0.3-0.7μM with a detection limit of 0.071μM. Furthermore, the detection of Cu2+ in the simulating surface water (by adding interfering metal ions in purified water) and the tap water (from municipal water in Beijing) were used to verify N-CQDs practical application.

Polyamide 11 nanocomposite feedstocks for powder bed fusion via liquid-liquid phase separation and crystallization

Within this contribution, the incorporation of nanoparticles (SiO2, Al2O3, TiO2) into the matrix of precipitated polyamide particles during thermally induced phase separation (TIPS) is demonstrated. The obtained polymer composite powders are tailored for their application in powder bed fusion (PBF). The flexible process allows to tune and adapt the powder properties to meet specific challenges like narrow particle size distribution, spherical particles, high additive contents and good distribution of the additive within the powder.Thermogravimetric analysis and electron microscopy prove the incorporation of the nano-sized additive into the matrix of the polymer. The influence of the additive material during polymer precipitation on the particle size distribution and shape of the powders is discussed. Thermal properties of the composite powders were assessed by dynamic and isothermal DSC for subsequent Avrami analysis. The observed acceleration of the crystallization kinetics could be attributed to the nucleating effect of the additive.All powders showed an easy-flowing (flow index ffC > 4) behavior. This allowed the deposition of homogeneous powder layers during PBF experiments also at high temperatures. The processability of the composite powders in the PBF process was demonstrated by single layer experiments.

In situ self-assembly preparation and characterization of CaO–ZrO2 nanopowders under vacuum

CaO–ZrO2 nanocomposite powders were prepared by in situ self-assembly method under vacuum. The effects of calcium oxide content on the physical phase composition and microscopic morphology of the as-prepared nanopowders were investigated. The results showed that the content of the tetragonal phase in the powders gradually increased with increasing calcium oxide content. When the calcium oxide content reached 10 wt%, the prepared CaO–ZrO2 nanopowders were a pure tetragonal phase with good dispersion and average particle size about 57 nm. In comparison to the situation in air, the amorphous carbon particles formed by the pyrolysis of organic matter under vacuum were evenly distributed on the surface of the nanocomposite particles or between them. In this way, direct contact of the nanoparticles was avoided, thus inhibiting their rapid growth at high temperatures and facilitating the formation of fine grains with high surface energy. The preliminary results indicated that the smaller average particle size and narrower particle size distribution of the nanocomposite powders prepared in vacuum were significantly beneficial for improving the bending strength of the nanoceramic products compared to that in air. It is expected to provide valuable information for further optimization of the controllable preparation of high-quality nanoceramic powders.

Mechanistic Insight into Solution-Based Atomic Layer Deposition of CuSCN Provided by In Situ and Ex Situ Methods

Solution-based atomic layer deposition (sALD) processes enable the preparation of thin films on nanostructured surfaces while controlling the film thickness down to a monolayer and preserving the homogeneity of the film. In sALD, a similar operation principle as in gas-phase ALD is used, however, with a broader range of accessible materials and without requiring expensive vacuum equipment. In this work, a sALD process was developed to prepare CuSCN on a Si substrate using the precursors CuOAc and LiSCN. The film growth was studied by ex situ atomic force microscopy (AFM), analyzed by a neural network (NN) approach, ellipsometry, and a newly developed in situ infrared (IR) spectroscopy experiment in combination with density functional theory (DFT). In the self-limiting sALD process, CuSCN grows on top of an initially formed two-dimensional (2D) layer as three-dimensional spherical nanoparticles with an average size of ∼25 nm and a narrow particle size distribution. With increasing cycle number, the particle density increases and larger particles form via Ostwald ripening and coalescence. The film grows preferentially in the β-CuSCN phase. Additionally, a small fraction of the α-CuSCN phase and defect sites form.