Narrow Particle Size Distribution Research Articles

Influence of tetraethyl orthosilicate coating on dielectric, impedance, and modulus properties of barium hexaferrite nanoparticles prepared by a modified sol–gel method

This work is devoted to study the comparison of the conduction mechanism in bare barium hexaferrite (BaFe12O19) nanoparticles and tetraethyl orthosilicate-coated (SiO2)x/BaFe12O19 (x = 5, 10, 15 and 20 wt. %) nanoparticles. The modified sol–gel method was adopted for the synthesis of these nanoparticles. The structures, morphologies, elemental composition, vibrational modes, and dielectric properties of these nanoparticles were studied by x-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy, Fourier transform infrared spectroscopy, and dielectric measurements, respectively. The crystallite size and particle size of BaFe12O19 nanoparticles decreased with SiO2 coatings, which can be attributed to the confinement of crystal growth of these nanoparticles with the coating. It was found that these (SiO2)x/BaFe12O19 nanoparticles have a uniform spherical shape, are non-agglomerated, and have a narrow particle size distribution. At room temperature, these (SiO2)x/BaFe12O19 nanoparticles showed distinctive behavior with varying frequency and SiO2 coatings. The experimental results in this work may provide fundamental support to the research and development of materials for energy storage devices.

Development and Functionalization of a Novel Chitosan-Based Nanosystem for Enhanced Drug Delivery.

Nowadays, infection diseases are one of the most significant threats to humans all around the world. An encouraging strategy for solving this issue and fighting resistant microorganisms is to develop drug carriers for a prolonged release of the antibiotic to the target site. The purpose of this work was to obtain metronidazole-encapsulated chitosan nanoparticles using an ion gelation route and to evaluate their properties. Due to the advantages of the ionic gelation method, the synthesized polymeric nanoparticles can be applied in various fields, especially pharmaceutical and medical. Loading capacity and encapsulation efficiency varFied depending on the amount of antibiotic in each formulation. Physicochemical characterization using scanning electron microscopy revealed a narrow particle size distribution where 90% of chitosan particles were 163.7 nm in size and chitosan-loaded metronidazole nanoparticles were 201.3 nm in size, with a zeta potential value of 36.5 mV. IR spectra revealed characteristic peaks of the drug and polymer nanoparticles. Cell viability assessment revealed that samples have no significant impact on tested cells. Release analysis showed that metronidazole was released from the chitosan matrix for 24 h in a prolonged course, implying that antibiotic-encapsulated polymer nanostructures are a promising drug delivery system to prevent or to treat various diseases. It is desirable to obtain new formulations based on drugs encapsulated in nanoparticles through different preparation methods, with reduced cytotoxic potential, in order to improve the therapeutic effect through sustained and prolonged release mechanisms of the drug correlated with the reduction of adverse effects.

Dry reforming of methane over sub-stoichiometric NiAl2O4-mediated Ni/Al2O3 catalysts

A series of Ni/Al2O3 catalysts were prepared from substoichiometric NiAl2O4 precursors (Ni/Al molar ratio between 0.5 and 0.05) were examined for the dry reforming of methane. The calcined spinel precursors and the corresponding reduced catalysts were characterised by N2 physisorption, X-ray fluorescence, X-ray diffraction, Raman spectroscopy, electronic microscopy coupled to elemental mapping, X-ray photoelectron spectroscopy and temperature-programmed techniques. Compared with the stoichiometric counterpart, nickel species present in Ni-deficient precursors were mostly in the form of a spinelic phase. After high-temperature reduction, narrow particle size distributions centred at 10 nm were obtained. The largest available nickel surface area (18 m2g−1) was exhibited by the catalyst derived from the precursor with a Ni/Al of 0.15. The NiAl2O4-mediated catalysts, especially those with Ni/Al molar ratio in the 0.15–0.25 range, exhibited a notable performance at 90,000 h−1 and 650 °C. The optimal catalyst (14%wt.%Ni), with 93%CH4 and 80%CO2 conversions, was also able to operate for 200 h despite the significant formation of carbonaceous nanotubes (around 1gCgCAT-1) and were examined.

The potential of starch-chitosan blends with poloxamer for the preparation of microparticles by spray-drying

Using biopolymers as wall materials in spray drying poses challenges, particularly in attaining flowability and thermal stability among their physicochemical properties. This paper addresses these challenges by preparing microparticles using a blend of starch–chitosan and a poloxamer, commercially named Pluronic® F127. We aimed to elucidate the effects of varying poloxamer concentrations on the resulting particles through the spray drying technique. Blends with a poloxamer concentration of 3% (w/v) demonstrated a notably higher yield, especially when compared to those with 0% and 1% concentrations. Microparticles with 3% and 5% (w/v) poloxamer displayed a narrower particle size distribution, with the 3% blend showing a superior yield attributed to arrangements of blend components that improve flowability. X-ray diffraction analysis showcased the characteristic peaks of A-type starch form, with shifts suggesting enhanced interactions between components. Microparticles with increased poloxamer content showed elevated thermal degradation temperatures, with the 3% blend registering a significant rise, opening avenues for encapsulating heat-sensitive bioactive. This study primarily focuses on the preparation and basic characterization of microparticles. It underscores the potential of blends with optimal poloxamer concentrations in microencapsulation, emphasizing further research to harness their capabilities thoroughly.

Preparation and characterization of high solid content cationic waterborne polyurethane with core‐shell structures

AbstractIn this study, core‐shell structured cationic waterborne polyurethane (WPU) dispersions with high solid content were prepared. To this end, prepolymer A was synthesized from polytetramethylene ether glycol (PTMG), isophorone diisocyanate (IPDI), castor oil (CO) and 1,4‐butanediol (BDO) without integration of the hydrophilic groups. Prepolymer B with hydrophilic groups was prepared from PTMG, IPDI, CO, BDO and N‐methyldiethanol amine (MDEA). WPU dispersion with a core‐shell structure could be generated by mixing, neutralizing, and emulsifying of the prepolymer A and the prepolymer B. The results indicated that the generation of WPU dispersions through this technique exhibited a milky appearance while the pH values range from 5.30 to 5.60. The optimal combination of prepolymer A and prepolymer B (at a ratio of 5:5) resulted in a dispersion with the highest solid content (50.4%), lowest viscosity (69 mPa·s), and narrowest particle size distribution. As the proportion of prepolymer A to prepolymer B decreases, the tensile strength of WPU film reduces while the elongation at break and glass transition temperature increases. Moreover, initially the contact angle with water was decreased instead of increase. However, modifications in a ratio of prepolymer A and B was not showed any significant impact on the thermal stability performance of the WPU films.

Magnetic and Fluorescent Dual-Labeled Genetically Encoded Targeted Nanoparticles for Malignant Glioma Cell Tracking and Drug Delivery.

Human glioblastoma multiforme (GBM) is a primary malignant brain tumor, a radically incurable disease characterized by rapid growth resistance to classical therapies, with a median patient survival of about 15 months. For decades, a plethora of approaches have been developed to make GBM therapy more precise and improve the diagnosis of this pathology. Targeted delivery mediated by the use of various molecules (monoclonal antibodies, ligands to overexpressed tumor receptors) is one of the promising methods to achieve this goal. Here we present a novel genetically encoded nanoscale dual-labeled system based on Quasibacillus thermotolerans (Qt) encapsulins exploiting biologically inspired designs with iron-containing nanoparticles as a cargo, conjugated with human fluorescent labeled transferrin (Tf) acting as a vector. It is known that the expression of transferrin receptors (TfR) in glioma cells is significantly higher compared to non-tumor cells, which enables the targeting of the resulting nanocarrier. The selectivity of binding of the obtained nanosystem to glioma cells was studied by qualitative and quantitative assessment of the accumulation of intracellular iron, as well as by magnetic particle quantification method and laser scanning confocal microscopy. Used approaches unambiguously demonstrated that transferrin-conjugated encapsulins were captured by glioma cells much more efficiently than by benign cells. The resulting bioinspired nanoplatform can be supplemented with a chemotherapeutic drug or genotherapeutic agent and used for targeted delivery of a therapeutic agent to malignant glioma cells. Additionally, the observed cell-assisted biosynthesis of magnetic nanoparticles could be an attractive way to achieve a narrow size distribution of particles for various applications.

Synthesis, Characterizations, and Recent Applications of the Silica-based Mobil Composition of Mesoporous Material: A Review

Silica-based mesoporous materials are a class of porous materials with unique characteristics such as ordered pore structure, large surface area, and large pore volume. This review covers the different types of porous material (zeolite and mesoporous) and the physical properties of mesoporous materials that make them valuable in industry. Mesoporous materials can be divided into two groups: silica-based mesoporous materials and non-silica-based mesoporous materials. The most well-known family of silica-based mesoporous materials is the Mesoporous Molecular Sieves family, which attracts attention because of its beneficial properties. The family includes three members that are differentiated based on their pore arrangement. In this review, the major applications of the Mobil Mesoporous Molecular Sieves family, such as catalysts, adsorbents, and drug delivery agents, have been surveyed. Furthermore, the synthesis of the Mesoporous Molecular Sieves materials, the silica sources, the importance of templates, and the mechanisms of the synthesis are discussed herein. Members of this material family are characterized by many physicochemical properties that are closely related to their high silica content, crystalline structure, and pore arrangement. Commonly, the members of this family have large surface areas, high pore volumes, small pore sizes, and narrow and uniform particle size distributions. These properties enable numerous industrial applications and opportunities for scientific studies to further develop existing materials or manufacture new ones.

Optimization of radial extrusion and pellet coating processes using PAT approaches

FDA's initiative Pharmaceutical CGMPs for the 21st century opened the door for introduction of several risk based approaches in pharmaceutical industry. One significant advancement that has emerged is the implementation of process analytical technology (PAT), which has opened doors for understanding and controlling complex technological processes. Two such processes, radial extrusion and pellet coating, offer a solid foundation for the application of PAT tools due to their numerous critical process parameters. The aim of the first part of the study was to optimize the neutral pellet production to produce the pellets with properties desired for successful film coating using design of experiments (DoE). In the second part the optimized pellets underwent film coating and the coating quantity was predicted in real or near real-time using in-line and at-line NIR probes and the performance of both probes was compared.The desired properties of the pellets, narrow particle size distribution, high sphericity and high process yield, were successfully achieved. Models for film coating quantity prediction using in-line and at-line NIR probe were successfully calibrated and tested by coating two additional batches. Despite the limited sample size for model calibration, at-line NIR exhibited excellent prediction performance and enabled accurate determination of process end-point. The coating quantity determined by UV/VIS spectroscopy in both test batches deviated by less than 2.0 % from the target value. However, the in-line NIR probe, primarily due to its inferior spectral resolution, displayed a slightly lower quality of the calibrated model and notable overprediction for the tested batches.

Limitation in the Performance of Fine Powder Separation in a Turbo Air Classifier

The deflector wheel classifier is a widely used device for the separation of fine powders in different industrial applications. The primary objective of the separation process is to achieve high-quality separation of fine powders characterized by a narrow particle size distribution and high separation sharpness. Theoretically, the reduction in the cut size is accomplished by decreasing the gas flow rate or increasing the rotational speed of the classifier, which amplifies the centrifugal forces compared to the drag forces exerted on the particles. This behavior is, indeed, observed in many cases, but it cannot be extrapolated arbitrarily. At their performance limit, classifiers may, against expectation, show an increase in cut size and, in addition, a reduction in the sharpness of the separation process. The limitation in the reduction in the cut size and in the improvement in the separation sharpness arises due to an imbalance between the operating rotational speed and flow rate, which results in a non-uniform flow field in the classifier. If the balance conditions are fulfilled, an optimum separation with a high separation sharpness can be achieved. In this work, CFD simulations validated by some experimental results are employed to represent this limitation, which is obtained by varying the operating parameters using different material densities with particles ranging from one to ten microns.

Optical Constants of Martian Dust Analogs at UV–Visible–Near-infrared Wavelengths

We present an advanced light-scattering model to retrieve the optical constants of three Martian dust analogs: Johnson Space Center regolith simulant, Enhanced Mojave Mars Simulant, and Mars Global Simulant. The samples are prepared to have narrow particle-size distributions within the geometric-optics domain. We carry out laboratory measurements to obtain the particle-size distributions, shapes, and diffuse reflectance spectra of the Martian analogs deposited on a surface. Our model framework includes a ray-optics code to compute scattering properties for individual particles, and a radiative-transfer treatment to simulate the surface. The irregular shapes of the dust particles are taken into account in the model. We compare our derived imaginary parts of the refractive indices with those in the literature and find that they are much smaller than the ones that are commonly used for Martian dust. A sensitivity study shows that the retrieved optical constants are sensitive to the particle shape, which needs to be accounted for in applications that use different shapes. Finally, the derived values are validated by using them to reproduce the reflectance spectrum of the Martian surface regolith as observed by the Nadir and Occultation for Mars Discovery instrument on board the ExoMars mission.

Comparison of size distributions of recovered particles generated from Ag wire in air by pulsed wire discharge and electric explosion of wire methods

Electric explosion of a wire (EEW) with discharge and pulsed wire discharge (PWD) are essential methods for producing nanosized and micronized metal particles. The study of Ag particle size distributions is important for Ag particle recovery from photovoltaic panel sheets using these methods performed in previous studies. In this study, we examined the size distributions of Ag particles generated from an Ag wire in air by EEW and PWD to clarify the difference between, and effects of these methods on particle generation. The particle size distribution generated in PWD was concentrated in a narrower range. The simulation results suggest that volume expansion occurred for a liquidized Ag wire in EEW and for a gasified Ag wire in PWD. Visualized images of processes and current waveforms in EEW and PWD indicated that after the wire explosion the restrike with plasma occurred in the expanding Ag particles in air in PWD. These results suggest that the narrower particle size distribution obtained in PWD may be attributable to monodisperse powderization by plasma evaporation of the gasified wire. These results show that PWD with plasma of an Ag wire in air effectively creates particles that are more monodispersed than those formed by EEW.

Imidazole-octyl mixed-mode stationary phase based on macroporous silica for the purification of ovomucoid and ovotransferrin.

A process-simplified hard template approach was established to synthesize the monodisperse macroporous silica microspheres with homogeneous structures by twice alkali-thermal treatment and calcination routes. Porous vinyl-functionalized polysesquioxane microspheres (V-PMSQ) were synthesized through a hydrolyzation-polycondensation method and used as templates. The template particles with large aperture and high pore volume were obtained by adjusting the pH value and reaction time of the twice alkali-thermal reaction. After calcination, monodisperse silica microspheres with an average pore size of 30nm, homogeneous pore structures, and narrow particle size distribution were fabricated, which can be directly used as chromatographic matrices without classification. After that, a new reversed-phase/strong anion-exchange (RP/SAX) mixed-mode stationary phase Sil-S-VOIM was prepared by bonding the 1-vinyl-3-octyl-imidazole ligands to the above silica microspheres through a "thiol-ene" click reaction. The performance of the Sil-S-VOIM column was evaluated by one acidic protein (transferrin) and two basic proteins (lysozyme, α-chymotrypsin) and compared to a single imidazole-modified Sil-S-VIM column and an octyl-modified Sil-C8 column, respectively. Due to the synergistic effect of electrostatic repulsion and hydrophobic interactions, baseline separations of the above proteins were observed only on the Sil-S-VOIM column, with resolutions of 2.55 and 2.01 between lysozyme and transferrin, and between transferrin and α-chymotrypsin, respectively, indicating good selectivity and separation ability compared with single-mode stationary phases. It was applied to the isolation of egg white samples with peaks identified by SDS-PAGE and MALDI-TOF-MS. The results showed that the selective retention and isolation of ovomucoid and ovotransferrin were successfully achieved, with yields of 78.8% and 67.2%, respectively. The protocol described in this work is simpler, faster, and has higher protein recovery. Overall, this new mixed-mode stationary phase provided a promising potential for the separation and determination of intact proteins.

Investigating the synergistic effects of high-pressure homogenization and pH shifting on the formation of tryptophan-rich nanoparticles

A combined treatment of high-pressure homogenization (HPH) and pH-shifting on the mixture of α-lactalbumin (α-LA) and tryptophan (Trp) was used to fabricate nanoparticles (α-LA-Trp-NP). The optimal α-LA/Trp ratio (5:1), HPH pressure (206.8 MPa), and recirculation time (40 min) was found to produce small α-LA-Trp-NP (243.0 ± 7.2 nm) with a narrow particle size distribution. Comparing the size and morphology of α-LA-NPs with α-LA-Trp-NPs indicated that the presence of Trp significantly affected the size and morphology of the NPs in the dry form. The stability of the α-LA-Trp-NPs was improved by using the combination of HPH and pH-shifting. The α-LA-Trp-NPs showed better freeze–thaw stability and retained the particle characteristics with heat treatment at 63 °C, 30 min after the freeze–thaw cycle. α-LA-Trp-NPs were also observed to have remarkable stability against pH changes and thermal treatments at 63 °C, 30 min, and 90 °C, 2 min.

Preparation of spherical tungsten powder with uniform distribution of lanthania by plasma spheroidization

The high ductile-brittle transition temperature of tungsten (W) makes it prone to crack during additive manufacturing. Incorporating lanthania (La2O3) to tungsten had been proven to be an efficient way to solve the cracking problem. However, the current incorporation methods are often accompanied by problems such as uneven dispersion of lanthania. In this study, W-La2O3 spherical powder with uniform distribution of lanthania was successfully prepared by spray granulation, heat treatment, and plasma spheroidization. The morphology, particle size distribution, flowability, apparent density, and element distribution of W-La2O3 powder at different stages were studied. The results show that the final obtained W-La2O3 powder has smooth surface and narrow particle size distribution, which also has excellent flowability (8.2 s/50 g) and apparent density (10.7 g/cm3). Moreover, it was observed that the plasma spheroidization resulted in the decrease of lanthania content in the powder, and the law of variation of lanthania content was obtained by the linear fitting method. The spheroidization mechanism of W-La2O3 composite powders was also proposed by studying the microstructure of incompletely spheroidized powders and the change of lanthania content.

PHYSICAL AND CHEMICAL EVALUATIONS OF TOPICAL RADIANCE SERUM CONTAINING NANOEMULSION COMBINATION OF ASTAXANTHIN AND ZEAXANTHIN: DESIGNED AS ANTI-WRINKLE AND SKIN-BRIGHTENING SERUM

Objective: The present study was conducted to formulate and evaluate the radiance serum containing the combination of astaxanthin and zeaxanthin nanoemulsion designed for anti-wrinkle and skin brightening serum by topical route of administration. Methods: The nanoemulsion containing astaxanthin and zeaxanthin was prepared using the self-nano emulsifying method, followed by incorporation into the radiance serum by the conventional mixing method. The quantity and ratio of surfactant, co-surfactant, and oil phase have been optimized in the previous study, as well as the radiance serum formula. The evaluation of the nanoemulsion and radiance serum was carried out by physical and chemical characterization. At the end of the study, an antioxidant activity of the serum containing nanoemulsion of astaxanthin and zeaxanthin was performed by DPPH method and the antioxidant activity was compared to its pure forms. The evaluation of the ex vivo permeation study was carried out to evaluate its possibility as an anti-wrinkle and skin brightener. Results: An astaxanthin and zeaxanthin nanoemulsion had a good physical properties with a globule size around of 20 nm (narrow particle size distribution), an entrapment efficiency range greater than 85%, and had a spherical morphology. The radiance serum had a good organoleptic and spreadability with the semifluid characteristic. Based on the result of antioxidant activity, the radiance serum had a highly active antioxidant activity. The radiance serum contained of astaxanthin and zeaxanthin nanoemulsion of 1% concentration, astaxanthin had a 2-6 times cumulative released compared than zeaxanthin (p<0.05) and all of the formulations exhibited a high skin permeation significantly. Conclusion: A formulation of nanoemulsion-based serum containing astaxanthin and zeaxanthin for topical delivery has been successfully developed. Based on the results of physical evaluation and especially from the permeation study, it seems that radiance serum containing astaxanthin and zeaxanthin nanoemulsion was potential to be used as an anti-wrinkle and skin brightening, however this function must be proven in further research.

A surprisingly narrow particle size distribution for polyacrylic acid nanospheres produced by precipitation polymerization and revealed by small-angle X-ray scattering

A surprisingly narrow particle size distribution for polyacrylic acid nanospheres produced by precipitation polymerization and revealed by small-angle X-ray scattering

Microscopic dissolution process of cellulose in alkaline aqueous solvents and its application in CNFs extraction - Investigating temperature as a variable

The target of this study is to gain a deeper understanding of the micro-dissolution process of cellulose in alkaline aqueous solutions and to develop a novel method for extracting cellulose nanofibrils (CNFs). Herein, the dissolution process of cellulose in alkaline aqueous solutions will be controlled by varying the temperature, and the undissolved cellulose will be analyzed to reveal the microscopic dissolution process of cellulose, and a novel process for extracting cellulose nanofibrils (CNFs) will be developed based on the findings. The crystalline structure of cellulose was gradually disrupted as the dissolution progressed, and the crystal form of cellulose changed gradually from cellulose I to cellulose II during the dissolution process, while all undissolved cellulose crystals remained as cellulose I. Cellulose, after its structure is disrupted during the dissolution process, will inevitably decompose into CNFs, and the microscopic dissolution process of cellulose follows a “top-down” dissolution sequence. The CNFs extraction method developed in this study can extract CNFs with high yield (>60 %) in a stable manner, as well as narrow particle size distribution, high crystallinity (>77 %), and good thermal stability. This study enhances the comprehension of the dissolution process of cellulose and paves a possible way for industrialization of CNFs production.

Multistep Extraction Transformation of Spent Coffee Grounds to the Cellulose-Based Enzyme Immobilization Carrier

The present study investigated the possibility of spent coffee ground (SCG) transformation to a cellulose-based enzyme immobilization carrier using a multistep extraction procedure. In the first step, SCGs were extracted with n-hexane by Soxhlet extraction in order to obtain SCG oil, while the remaining solid residue was subjected to continuous solvent flow sequential subcritical extraction with 96% and 50% ethanol and water. Afterwards, the obtained solid residue was subjected to alkaline liquefaction with 8% NaOH in order to remove lignin and produce cellulose-enriched SCGs as a potential enzyme immobilization carrier. Multistep extraction transformation of SCGs was monitored by chemical analysis of extracts and obtained solid residues. Soxhlet extraction of 100 g of SCGs yielded 10.58 g of SCG oil rich in linoleic and palmitic acid, while continuous solvent flow sequential subcritical extraction of 100 g of defatted SCGs yielded a total of 1.63 g of proteins, 5.58 g of sugars, 204 mg of caffeine, 76 mg of chlorogenic acid, and 11.97 mg of 5-(hydroxymethyl)furfural. Alkaline liquefaction of 100 g of sequentially extracted defatted SCGs by 8% NaOH yielded 7.45 g of proteins, 8.63 g of total polyphenols, 50.73 g of sugars, and 20.83 g of cellulose-enriched SCGs. Based on the characteristics of cellulose-enriched SCGs including a volume-weighted mean particle size of 277 μm, relative narrow particle size distribution with a span value of 1.484, water holding capacity of 7.55 mL/g, and a lack of carrier leakage, it could be safely concluded that produced cellulose-enriched SCGs fulfills criteria to be used as potential enzyme immobilization carrier. Overall, it seems that the proposed multistep extraction transformation of SCGs has great potential to be used for the production of several high-value added products.

SDS-capped 1-pyrenecarboxaldehyde nanoprobe for selective detection of Cu2+ ion from water samples: Spectroscopic approach.

Sodium dodecyl sulfate (SDS)-capped 1-pyrenecarboxaldehyde nanoparticles (PyalNPs) were prepared using a reprecipitation method in an aqueous medium and exhibited red-shifted aggregation-induced enhanced emission (AIEE). The dynamic light scattering (DLS) examination showed narrower particle size distribution with an average particle size of 41 nm, whereas -34.5mV zeta potential value indicate the negative surface charge and good stability of nanoparticles (NPs) in an aqueous medium. The AIEE was seen at λmax = 473 nm in a fluorescence spectrum of a PyalNP suspension. In the presence of Cu2+ ions, the fluorescence of PyalNPs quenches very significantly, even in the presence of other metal ions like Ba2+ , Ca2+ , Cd2+ , Co2+ , Al3+ , Fe2+ , Hg2+ , Ni2+ and Mg2+ . The changes in the fluorescence lifetime of PyalNPs in the presence of Cu2+ ions suggested that the type of quenching was dynamic. The fluorescence quenching data for the NPs suspension fitted well into a typical Stern-Volmer relationship in the concentration range 1.0-25 μg/ml of Cu2+ ions. The estimated value of the correlation coefficient R2 = 0.9877 was close to 1 and showed the linear relationship between quenching data and Cu2+ ion concentration. The limit of detection (LOD) was found to be 0.94 ng/ml and is far below the tolerable intake limit value of 1.3μg/ml accepted by the World Health Organization for Cu2+ ions in drinking water. The fluorescence quenching approach for a SDS-capped Pyal nanosuspension for copper ion quantification is of high specificity and coexisting ions were found to interfere very negligibly. The developed method was successfully applied for the estimation of copper ions in river water samples.

Fabrication of Novel Crosslinking Carboxylic Styrene-Acrylate Latices as Binders for Exterior Flexible Facing Tiles.

To overcome the shortcomings of the temperature sensitivity of exterior flexible facing tiles (EFFIs), a series of crosslinking carboxylic styrene-acrylate (SA) latices were prepared via the semicontinuous seed emulsion polymerization of glycidyl methacrylate (GMA), methacrylic acid (MAA), acrylic acid (AA), butyl acrylate (BA), and styrene (St), and were applied as binders to fabricate EFFTs with mineral powder. The obtained latices exhibited Bragg diffraction because of the narrow particle size distribution. Owing to the low dosage of emulsifiers and the crosslinking reaction between the epoxy group and the carboxyl group, the latex films displayed excellent water resistance, with water adsorption as low as 7.1%. The tensile test, differential scanning calorimeter (DSC) test, and dynamic mechanical analysis (DMA) indicated that at a GMA dosage of 4-6% the latex films had high mechanical strengths, which remained relatively stable in the temperature range of 10 to 40 °C. The optimal AA dosage was found in the range of 2 to 3%, at which the wet mixture exhibited good processability, conducive to forming an EFFT with a compact microstructure. Using the optimal SA latex, the obtained EFFT displayed a series of improved performances, including low water absorption, high mechanical strength, and stable self-supporting ability over a wide temperature range, exhibiting the application potential in the decoration and construction industries.