Particle Size Determination Research Articles

Preparation, Physicochemical Characterization and Anti-Fungal Evaluation of Amphotericin B-Loaded PLGA-PEG-Galactosamine Nanoparticles.

Purpose: The present study aimed to formulate PLGA and PLGA-PEG-galactosamine nanoparticles (NPs) loaded with amphotericin B with appropriate physicochemical properties and antifungal activity. PLGA was functionalized with GalN to increase the adhesion and antifungal activity of NPs against Candida albicans.Methods: The physicochemical properties of NPs were characterized by particle size determination, zeta potential, drug crystallinity, loading efficiency, dissolution studies, differential scanning calorimeter (DSC), X-ray powder diffraction (XRPD), and Fourier transform infrared (FT-IR). Antifungal activity of the NPs at different drug/polymer ratios was examined by determining minimum inhibitory concentrations (MICs). Results: the FT-IR and 1 HNMR analysis successfully confirmed the formation of PLGA- PEG-GalN NPs. The PLGA NPs were in the size range of 174.1 ± 3.49 to 238.2±7.59 nm while PLGA-GalN NPs were 255.6 ±4.08 nm in size , respectively. Loading efficiency was in the range of 67%±2.4 to 77%±1.6, and entrapment efficiency in the range of 68.185%±1.9 to 73.05%±0.6. Zeta potential and loading efficiency for PLGA-GalN NPs were –0.456, 71%. The NPs indicated an amorphous status according to XRPD patterns and DSC thermograms. The PLGA-PEG-GalN NPs showed higher fungistatic activity than PLGA NPs. Conclusion: the results demonstrated that the antifungal activity of PLGA-PEG-GalN NPs was higher than pure amphotericin B and PLGA NPs.

Physicochemical characterizations of ostholehydroxypropyl-β- cyclodextrin inclusion complexes with high-pressure homogenization method

The purpose of this research was to evaluate the inclusion complex composed of osthole and hydroxypropyl-β-cyclodextrin (HP-β-CD) by using two preparative techniques, neutralization and high-pressure homogenization (HPH) method. The solid complexes were characterized by differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), particle size determination, and dissolution test. The DSC diagrams indicated that the solid complex from the HPH method led to more complete complexation than that of physical mixture and neutralization method. The formation of inclusion complex between drug and cyclodextrin (CD) was verified by FTIR analysis. The smallest mean particle size of solid complex was acquired from the HPH method. The results proved that the rate of drug release for the inclusion complex obtained from the HPH method was much faster than those of neutralization, physical mixture, HP-β-CD and osthole alone.

"DIY" Silica Nanoparticles: Exploring the Scope of a Simplified Synthetic Procedure and Absorbance-Based Diameter Measurements.

In this study, the classical Stöber silica synthesis protocol was used to test the limits of simplification in the preparation and size determination of nanoparticles. The scope of three-ingredient, one-pot synthesis was established in conditions of regular 96% and 99.8% ethanol as solvent, with aqueous ammonia as the only source of base and water. Particles with diameters in the 15–400 nm range can be reliably obtained with this straightforward approach, and the direct relationship between the size and the product of concentrations of water and ammonia is evidenced. Furthermore, the idea of a linear approximation for Mie scattering in particular conditions is discussed, using experimental data and theoretical calculations. A simple, fast method for particle size determination utilizing a UV-Vis spectrophotometer—an easily accessible instrument—is explained, and shows a level of error (<0.5 SD) that can be acceptable for less rigorous laboratory use of nanoparticles or serve as a quick means for testing the influence of minor alterations to known synthetic protocols. This work aims to show that nanoparticle synthesis can (and should) become a regular occurrence, even in non-specialized labs, facilitating research into their new applications and inspiring outside-the-box solutions, while discussing the drawbacks of a more relaxed synthetic regimen.

Computational Fluid Dynamics Simulation of Iron Ore Reduction in Industrial‐Scale Fluidized Beds

Detailed simulations of industrial‐scale fluidized beds such as the FINEX process are still unfeasible due to the wide range of spatial scales. Due to the computational limitations it is common to apply coarse grids, which do not resolve all relevant structures. In our previous study (Schneiderbauer, AIChE J. 2017, 63, 3562), we have presented subgrid models, which enable the coarse grid simulation of dense large‐scale gas–solid flows. Herein, these corrections are applied to a parcel‐based the dense discrete phase model (DDPM), allowing to study the hydrodynamics of the FINEX process. Furthermore, the parcel approach is augmented by an unreacted shrinking core model (USCM) to account for the direct reduction of the iron ore particles by the reducing agents of H2 and CO. This DDPM model is tested first for a cold pilot‐scale fluidized bed, and second, the USCM approach is validated for the direct reduction in a lab‐scale fluidized bed. Finally, the model is applied to the FINEX process. The results show fairly good agreement with measurements of the average bed voidage and with experimentally determined particle size distributions. The results further indicate that fines are immediately reduced, whereas the reduction of the largest ore grains takes considerably longer.

Floating Microspheres Based Nizatidine Gastro Retentive Formulation to Control the Release of Drug

Present research aimed at formulation development and characterization of the floating drug delivery system of Nizatidine, a H2-receptor antagonist, widely prescribed in gastric ulcers and duodenal ulcers. Nizatidine loaded floating microspheres were developed by the solvent diffusion-evaporation method using polymers hydroxypropyl methylcellulose (HPMC) and microcrystalline cellulose (MCC) to prolong the gastric retention time of the drug for the therapeutic management of gastric disorders like ulcers. Further, the developed formulations were characterized for percentage yield, drug entrapment, floating behavior, shape and surface morphology, in vitro drug release, determination of particle size and Zeta potential, in vitro stability studies, and antimicrobial activity. The percentage yield of the different formulation was found to be a range of 75.65– 81.25%, drug entrapment efficacies of different formulations were in the range of 65.56- 75.65% w/w, formulation F4 of floating microsphere was found to be 178.5 nm, Zeta potential of optimized formulation F4 of floating microsphere was found -33.6 Mv, Surface morphology of formulation examines at two different magnification 55X which illustrate the smooth surface of Microspheres. The in vitro drug release pattern of Nizatidine loaded optimized floating microsphere was subjected to the goodness of fit test by linear regression analysis, and it was observed that ‘r’ values of microsphere were maximum for zero-order, i.e., 0.969 hence indicating drug release from formulations follow zero-order kinetics with non-fickian diffusion mechanism which in turn prolonged drug release. The antimicrobial activity of the optimized formulation showed clear fluid with no development of turbidity. It inferred better clearance from infection than plain drug solution at the same doses. Floating microspheres of Nizatidine as gastro retentive dosage forms precisely control the release rate of Nizatidine to a peculiar site and expedite an immense impact on health care.

Performance analysis of rotary blast-hole drills through machine vibration and coarseness index mapping – A novel approach

• A novel performance evaluation technique for rotary blast-hole drills performance. • Correlation of drill performance with machine-vibration and drill cuttings. • Drill cuttings collection and analysis as per ASTM standard. • Determination of mean particle size using Rosin-Rammler Diagram. • Obtaining Drill Vibration Index and the optimal drill operating regime. The performance of rotary drill machines commonly used in open-pit mines is measured based on the rate of penetration (ROP) and the bit wear. This paper develops a novel performance evaluation technique to obtain optimal drill operating regime through machine vibration and coarseness index mapping. The vibration levels of blast-hole drilling machines in axial and lateral directions were determined using accelerometers placed at the mast. The mean particle size (d) and characteristic particle size distribution curves for the drilled hole were plotted using sieve analysis and Rosin Rammler diagram. ROP showed an increasing trend with Mean particle size (d) with a correlation of R 2 = 0.61 and a decreasing trend with vibration for varied pulldown force and torque at a different rotational speed. A drill vibration index (DVI) is introduced as an indicator of vibration severity of the drill machine, and its relationship was studied with ROP and average mean particle size.

Reconstruction of angle-resolved backscattering through a multimode fiber for cell nuclei and particle size determination

We demonstrate reconstruction of angle-resolved optical backscattering after transmission through a multimode fiber. Angle-resolved backscattering is an important tool for particle sizing, and has been developed as a diagnostic modality for detecting epithelial precancer. In this work, we fully characterized the transfer function of a multimode fiber using a plane-wave illumination basis across two dimensions. Once characterized, angle-resolved scattering information which has been scrambled by multimodal propagation can be easily and accurately reconstructed. Our technique was validated using a Mie theory-based inverse light scattering analysis (ILSA) algorithm on polystyrene microsphere phantoms of known sizes. To demonstrate the clinical potential of this approach, nuclear morphology was determined from the reconstructed angular backscattering from MCF-10A human mammary epithelial cell samples and validated against quantitative image analysis (QIA) of fluorescence microscopy images.

Active carbon/TiO2 composites for photocatalytic decomposition of benzoic acid in water and toluene in air

The present work describes the preparations of active carbon (AC) – titania composites with 2 different AC/TiO2 ratios, their characterization using SEM, BET, determination of particle size, and evaluation of adsorption ability and photocatalytic activity using benzoic acid (BA) in the aqueous phase and toluene in the gaseous phase. Composite materials based on AC/TiO2 were prepared from two types of active carbon (having a BET surface area of 1737 m2 g−1 and 890 m2 g−1, respectively) and TiO2 (P25, BET surface area 45 m2 g−1) by mixing. The main studied parameter was milling of AC. Immobilized photocatalyst films were prepared by drop-casting of aqueous composite suspensions on glass substrates and drying. The composite films prepared from milled AC have much better adhesion to substrate in aqueous media than those from non-milled AC, which is due to a decrease of particle size by about 1 order during milling. The ability of composites prepared from milled AC to remove BA was more than 2.5 times higher than that of composites from non-milled AC. In comparison with TiO2, prepared composites showed similar or higher photocatalytic activity and the irradiation of AC/TiO2 composites in aqueous suspensions resulted in the generation of a comparable concentration of the hydroxyl radical spin-adduct (DMPO-OH) as with TiO2.

Microencapsulation of the Extract from Euterpe edulis Co-product: An Alternative to Add Value to Fruit Agro-Chain

The objective of this work was to evaluate the main characteristics of microparticles obtained from an extract of the Euterpe edulis (jucara) co-product, and in addition evaluate their stability during storage at 30 °C for 60 days. For this purpose, the wall material composition, for spray dryer process, was selected by means of sedimentation assays from suspensions formulated using modified starch, maltodextrin, and whey protein concentrate. The most stable suspensions were those formulated using 100% modified starch and modified starch + maltodextrin (1:1). Microparticles were evaluated for determination of moisture, solubility, hygroscopicity, morphological characteristics, particle size, phenolic compounds, antioxidant potential, and glass transition temperature. The results showed that the physical characteristics of the microparticles were not influenced significantly by the reduction of modified starch percentage in the formulations, except for glass transition temperature. Microparticles presented solubility higher than 76%, and hygroscopicity less than 9%. Spherical microparticles with an average size of less than 10 μm were obtained. The highest process yield (62%) and glass transition temperature (47 °C) were observed when suspension was elaborated using modified starch only. After 60 days, microparticles presented anthocyanins retention superior to 92%, as well as 80%, 99%, and 99% retention of the antioxidant capacity by DPPH, ABTS, and FRAP methods, respectively. Therefore, the microencapsulation of the jucara co-product extract allowed obtaining a stable product containing bioactive compounds.

Towards a new and general method for decoding the soil texture from laser diffraction spectra

Laser diffraction (LD) is a modern method for determining particle size distribution of soils and sediments. When deciphering particle size distribution, the area under the differential LD-spectrum is determined, limited by the vertical boundaries at the group edges according to the FAO-classification. In fact, there are no real vertical boundaries between the fractions of the particles, and the fractions themselves are distributed on a scale of size according to normal distribution. To eliminate the errors in the fractions content, deconvolution procedure for separating the original particle size distribution LD-spectrum is proposed. It resulted in a different share of the fractions compared to the common calculation method of the fractions content by FAO-classes. It is possible to detect new invisible fractions and, conversely, to exclude fractions defined within FAO vertical boundaries. In addition, the new indicator dispersion of LD-fractions (D) is proposed, which provides information on the property of individual fractions by particle size. Vertisols’ texture was heavier after deconvolution, especially in the Stavropol Vertisols. Vertisols had relatively low dispersion D < 0.7, which means relative homogeneity of LD-fractions. Northern Italy Andosols, however, had lighter texture after deconvolution. The number of LD-fractions was less than the number of FAO-fractions, while clay and fine sand (63–200 μm) LD-fractions were absent. It is likely due to the increase in LD-fractions dispersion, as evidenced by the high value of D (1.5).

Characterization and internalization of nanodiamond–trehalose conjugates into mammalian fibroblast cells of naked mole rat

Trehalose is a natural compound produced by certain organisms to cope with freezing and thawing. It, therefore, has a potential for use as a cryoprotective agent, but the absence of specific receptors requires alternative mechanisms of intracellular delivery. Nanodiamonds are a non-toxic, carbon-based technology, and when conjugated with trehalose, they may offer a suitable delivery system for trehalose internalization. The characteristics of commercially available detonation nanodiamonds with carboxylated (ND-COOH) or hydrogenated (ND-H) surface structures were characterized using dynamic light scattering (DLS) to determine particle size and zeta potential. Trehalose adsorption to the two nanodiamonds was examined at varying concentrations and pH values using Fourier-transform infrared spectroscopy (FT-IR). Naked mole rat fibroblasts were used to study internalization of three different suspensions of trehalose-conjugated nanodiamonds: nanodiamond alone (T1); nanodiamond + trehalose intense wash (T2); and nanodiamond + trehalose moderate wash (T3) at concentrations of 10 or 50 μg/ml (6 or 36 μg/cm2) and exposure durations of 2 or 24 h. Internalization was evaluated by flow cytometry analysis and dark-field microscopy. Cells incubated with the three nanodiamond suspensions were examined by phase-contrast microscopy to evaluate cell morphology after the addition of propidium iodide dye which detects necrotic cells. ND-COOH and ND-H suspensions had mean particle diameters of 8 nm and 32 nm, and zeta potentials of − 49 mv and + 53 mv, respectively. FT-IR absorption spectra showed that trehalose adsorption to ND-COOH and ND-H was greatest at a trehalose concentration of 50 mM and at a neutral pH. ND-COOH particles displayed the greatest affinity with trehalose. Flow cytometry analysis indicated dose- and exposure-dependent increases in light scattering (correlating with increased internal complexity) for all nanodiamond suspensions (T1, T2, and T3), with the highest levels of internalization observed with the 50 μg/ml concentration at exposure durations of 24 h. Untreated cells exhibited low light scattering. There were no significant differences between T1, T2, and T3 in the number of cells internalized. Cell size was not altered by internalization. Internalization of the nanodiamond suspensions was confirmed by dark-field microscopy. Toxicology experiments indicated some alterations to cell morphology, but no effect of the nanodiamond suspensions on cell counts or cell death. Nanodiamond delivery systems offer potential for the internalization of trehalose in mammalian cells. Further experiments should investigate the efficacy of trehalose–nanodiamond particles as cryoprotective agents.

PHYSICAL AND CHEMICAL STUDIES OF SLAG OF PRODUCTION OF LOW-CARBON FERROCHROME - COMPONENT OF HEAT-RESISTANT BINDER MATERIAL

The aim of the work is physicochemical studies of chemical and mineralogical composition of the slag from the production of low-carbon ferrochrome proposed to use as a component of heat-resistant binder. As a result of studies, it was found that the main crystal phase in the slag is calcium orthosilicate in the form of γ-Ca2SiO4 modification, which is also partially in the form of α-Ca2SiO4, and magnesian silicates in the form of forsterite Mg2SiО4. The main properties of the slag such as density, specific surface, dispersiveness, refractoriness are determined by the properties of the dominant mineral- calcium orthosilicate. Under conditions of slow cooling of the slag melt, the main mineral in the slag composition, i.e. calcium orthosilicate β-Ca2SiO4 passes into γ-Ca2SiO4 modification with increase in the volume of crystal lattice by ~ 12%, which leads to self-destruction and transition of the slag to a dust state. The results of studies of the specific surface, determination of the average particle size, the results of sieve analysis showed that the slag from the production of low-carbon ferrochrome is a finely dispersed gray powder with the following characteristics: the specific surface is 2955 cm2/g, the average particle size is 6.8 μm, the true density is 3.01 g/cm3, the bulk density is 739 kg/m3. When using the finely dispersed slag from the production of low-carbon ferrochrome as a component of composite binders, the energy-consuming process of its fine grinding can be eliminated. Currently, the slag from the production of low-carbon ferrochrome is practically not used as a secondary mineral raw material. However, the physicochemical properties of the minerals making up the slag allow to recommend it as a component for the manufacture of heat-resistant materials. The results of physical and chemical studies can be used to develop effective technologies for integrated processing of low-carbon ferrochrome slags.

Enabling new exploration opportunities on planetary surfaces: In situ geochemical characterization in soils by dielectric spectroscopy onboard the AXEL rover system

In the work, we present dielectric spectroscopy (DS) is an analytical method capable of characterizing and quantifying electrochemically active materials (water/ice, ions, etc.) in planetary regoliths. Detection of these materials occurs when a small amount of energy is applied to an in situ sample, causing perturbation in the form of potential kinetic energy and inducing polarization and/or relaxation processes in materials of interest. The frequency dispersion on the electrical properties of impendences, relative permittivity, and conductivity spectra represents chemical and physical properties in association with inherent material properties. Therefore, measuring these energetic states can provide a unique fingerprint of the materials, depending on the frequencies that are scanned. In the case of water content in soils, the Debye equivalent circuit model can accurately predict its electrical properties and provide excellent quantification of the water content in soils.Use of DS is enabled by miniaturization of the key components and the low power requirements. DS is therefore capable of offering substantial scientific returns as an in situ sampling and non-destructive measurement technique, making it ideally suitable for deployment onboard many smaller space exploratory platforms. This work reports the first deployment use of DS from a field test for geochemical characterization of in situ soils, specifically on the quantification of water onboard the AXEL mobility system in the Mojave Desert.Laboratory testing has confirmed the sensitivity of DS with respect to particle size (fine vs coarse) determination as well as water content (down to 0.01 ​wt%) under a wide range of environmental conditions. Water content associated with bound and bulk water was uniquely identified in the soil mixture. We also describe a field demonstration using DS using two distinct insertion dielectric probes specifically design for sub-surface measurements, verifying their mechanical robustness and chemical stability. The field measurements are in good agreement with laboratory data and effectively quantified water content at about 3.0 ​wt% and 8.0 ​wt% for field test sites #1 and #2, respectively.

Using mechanical activation of quartz to enhance the compressive strength of metakaolin based geopolymers

The present work synthesized geopolymer with quartz mechanical activated at different time, and the strengthening mechanism of geopolymer by activated quartz was investigated. The changes of quartz before and after activation and the microstructure of geopolymer was explained by the determinations of particle size, specific surface area and the concentration of reactive Si, as well as XRD, XPS and NMR measurement. With the activation time of quartz increasing from 0 to 60 min, the compressive strength of geopolymer increased from 31.5 to 55.2 MPa. The results showed that increase of quartz reactivity is mainly due to the formation of the Si-centered radicals and non-bridging oxygen on the surface rather than the changes in physical property or crystal structure of quartz. The high activity tetrahedra Si with non-bridge oxygen on the surface of quartz replace the tetrahedra Al in geopolymer gel, which lead to a Si-rich gel formed around quartz and the improvement of compressive strength.

Size Measurement of Extracellular Vesicles and Synthetic Liposomes: The Impact of the Hydration Shell and the Protein Corona

Size characterization of extracellular vesicles (EVs) and drug delivery liposomes is of great importance in their applications in diagnosis and therapy of diseases. There are many different size characterization techniques used in the field, which often report different size values. Besides technological biases, these differences originate from the fact that various methods measure different physical quantities to determine particle size. In this study, the size of synthetic liposomes with nominal diameters of 50nm and 100nm, and red blood cell-derived EVs (REVs) were measured with established optical methods, such as dynamic light scattering (DLS) and nanoparticle tracking analysis (NTA), and with emerging non-optical methods such as microfluidic resistive pulse sensing (MRPS) and very small-angle neutron scattering (VSANS). The comparison of the hydrodynamic sizes obtained by DLS and NTA with the sizes corresponding to the excluded volume of the particles by MRPS enabled the estimation of the thickness of the hydration shell of the particles. The comparison of diameter values corresponding to the boundary of the phospholipid bilayer obtained from VSANS measurements with MRPS size values revealed the thickness of the polyethylene glycol-layer in case of synthetic liposomes, and the thickness of the protein corona in case of REVs.

The Study and Exposure of Law of Distribution Protein Substances in Uroliths

The characterization of urinary stones mineral and organic composition in Omsk region and Saint-Petersburg (Russia) was studied. It was established that nature and amount of amino acids and trace elements in composition of phosphate, oxalate and urate urinary stones are different. For studying processes of formation of the main mineral phase of urinary stones on the model systems powders of calcium oxalate monohydrate and hydroxyapatite with molar Ca/P ration 1.57 –1.67 were synthesized. The determination of electrokinetic properties and particle size of synthesized powders were made. The effects of amino acids (glutamic acid, glycine and lysine) on the process of formation of calcium oxalate monohydrate and hydroxyapatite were investigated. It was shown that amino acids inhibited growth and aggregation of calcium oxalate monohydrate and hydroxyapatite particles and preferential adsorb on to their crystal surfaces.

INFLUENCE OF BACKGROUND ELECTROLYTE AND SURFACE-ACTIVE SUBSTANCES ON EFFICIENCY OF ELECTRO-FLOTATION EXTRACTION OF HARDLY SOLUBLE EUROPIUM COMPOUNDS

Europium and its compounds are widely used in high-tech processes of nuclear and hydrogen energy, electronics, medicine and other fields. In this work, the regularities of electroflotation extraction of hardly soluble europium compounds from model systems were obtained and analyzed. The aim of the work is to obtain data on the process of electroflotation extraction of hardly soluble europium (III) compounds from model systems with background electrolyte and the addition of surface-active substances, establishing optimal conditions for efficient extraction of hardly soluble europium (III) compounds. The research was conducted at room temperature (20 ± 2 °C) in a non- current electric flotator of periodic action, which is made in the form of a vertical column. The cross-sectional area of the electric flotator is 10 cm2, the volume of the treated solution is 500 ml, the height of the apparatus is 800 mm, and the sampling valve is located at a height of 40 mm from the electrode unit. The electrode unit consists of an insoluble anode made of ORTA (titanium with ruthenium oxide coating) and of a cathode made of stainless steel mesh (cell size 0.5 × 0.4 mm, wire thickness 0.3 mm). The mass concentration of europium (III) was determined by a mass-spectrometer with inductively coupled plasma of Termo Scientific brand. Determination of particle size and particle size distribution, surface charge of particles of the dispersed phase (ξ) were carried out using a Photocor Compact-Z laser particle analyzer. The efficiency of the process of extracting hardly soluble compounds of Eu3+ was evaluated by the degree of extraction α (%). The objects of study are colloid-dispersed systems of poorly soluble compounds of europium (III) in aqueous solutions in the presence of surface-active substances of various nature and background electrolytes. The initial aqueous solution contains: СEu3+ - 0.1 g/l, Cbackground electrolyte - 1 g/l, background salts: NaCl, NaNO3, Na2SO4; Csas - 5 mg/l. It has been shown that for each type of solution the efficiency of the electroflotation process is achieved at certain pH. It is established that the optimal conditions for the extraction of europium (III) compounds are: volume current density, Jv = 0.4 A/l; process duration 10 min. For nitrate background the degree of extraction is maximum at pH 10 - 11 and at the presence of an anionic surfactant additive in the solution (Оxy surfactant A1218). When extracting europium (III) compounds from a system with a sulphate background the best results were obtained at pH values of 8 and 10, as well as the addition of an anionic and, or cationic (Septa surfactant XEV70) surfactant. Chloride background showed the best conditions for the extraction of europium (III) at pH 7 with the addition of a non-ionic surfactant of PEO-1500 brand. The degree of extraction of europium is 98-99%.

Monodisperse Pt-Co/GO anodes with varying Pt: Co ratios as highly active and stable electrocatalysts for methanol electrooxidation reaction

The intense demand for alternative energy has led to efforts to find highly efficient and stable electrocatalysts for the methanol oxidation reaction. For this purpose, herein, graphene oxide-based platinum-cobalt nanoparticles (Pt100−xCox@GO NPs) were synthesized in different ratios and the synthesized nanoparticles were used directly as an efficient electrocatalyst for methanol oxidation reaction (MOR). The characterizations for the determination of particle size and surface composition of nanoparticles were performed by transmission electron microscopy (TEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The structure of the catalysts was detected as face-centered cubic and the dispersion of them on graphene oxide was homogenous (distributed narrowly (4.01 ± 0.51 nm)). Cyclic voltammetry (CV) and chronoamperometry (CA) was utilized for testing electrocatalytic activities of all prepared NPs for the methanol oxidation reaction. It was detected that the newly produced NPs were more active and stable than commercially existing Pt(0)/Co nanomaterial in methanol electro-oxidation in acidic media.

Role of dimethyl ether in incipient soot formation in premixed ethylene flames

Emissions of soot particles exert crucial impact on human health and the environment. Previous researches show that a partial replacement of fossil fuels with oxygenated fuels is supposed to reduce soot emission. However, the crucial information of soot size distributions is unclear, although small particles are more dangerous than large particles. In this paper, dimethyl ether (DME) is selected among the oxygenated fuels for the investigation of the doping effect on nascent soot formation. DME was doped in the burner-stabilized rich premixed ethylene/oxygen/argon flames at various mixing ratios. Flame temperature profiles were measured using R-type thermocouples with radiation correction. A scanning mobility particle sizer (SMPS) with a sampling system was used to determine particle size distributions (PSDs) of soot-containing combustion products with immediate dilution. Thermo-gravimetric analysis (TGA) complemented with elemental analysis (EA) was conducted to detect the chemical properties of formed soot particles. Additionally, species profiles of the experimental flame conditions were provided from simulations. The experimental PSDs showed that DME addition could slow down soot evolution process, while lead to a slight increase in incipient soot with size below 4 nm. When DME added, the production of benzene was suppressed due to the reduced concentrations of acetylene and propargyl, and thus soot nucleation. Meanwhile, soot oxidiation was enhanced because the OH radical and the oxidizability of soot particles are both increased. Considering the slight increase of sub-4 nm soot, the effect of oxygenated-PAHs (OPAH) was emphasized. The production of OPAH suppressed soot surface growth, which leading to the relatively lower consumption of sub-4 nm soot in DME added flames.As a result, DME cannot be simply regarded as a clean fuel due to the enhanced formation of sub-4 nm soot particles. When applying oxygenated fuels into practice, it is necessary to pay more attention to the size distributions of the emitted particles, and conduct appropriate post-processing techniques to reduce the emissions of small particles.

Comparison of pipette method and state of the art analytical techniques to determine granulometric properties of sediments and soils

The determination of particle size distribution is a crucial issue in various fields of earth sciences (e.g., Quaternary research, sedimentology, stratigraphy, structural geology, volcanology), environmental sciences as well as diverse industrial applications (e.g., pharmaceuticals, cement industry). New measurement techniques developed as a result of industrial demands have also gained ground in environmental and Earth sciences research. The new techniques (especially laser diffraction) have enabled the particle characterisation in the broader size-range with a more detailed resolution. Still, they have to be compared with data obtained by classical methods. In light of the above, the primary aim of our research is to examine the methods of particle size determination critically. Excessive oversimplifications of particle size analyses routinely have used in paleo-environmental and paleo-climatological reconstructions, and other sedimentary studies, as well as insufficient knowledge of the background of the applied methods, distort the interpretation of the results. Over the past four decades, laser diffraction particle size analysers have proven to be practical tools of particle size characterisation. However, the shape of the natural sediment and soil particles are irregular and, therefore, affects the particle size distribution results obtained by different methods. The results of the traditional pipette method differed from laser diffraction results. The presence or absence of the pretreatments did control the differences between the two techniques. The results of Fraunhofer optical method were significantly different from Mie theory because it can detect much lower volume percentages of finer particles. Grain size results of coarse-grained samples measured by different laser diffraction devices were more comparable than the results of more clayey samples. The ratios of different sizes were changed due to the hydrochloric acid and hydrogen peroxide pretreatments. The comparison of different techniques is necessary to revaluate standards in grain size measurements which can enable the shift from conventional methods to more productive and reproducible methods. Still, light scattering techniques have not yet been able to displace classical methods in Earth sciences completely, in contrast to industrial applications.