Unimodal Size Distribution Research Articles

Sulfidization-free synthesis of well dispersed (Gd,La)2O2S:Pr3+ nanopowders and the effect of La3+ on structure and luminescence

Pr3+ activated Gd2O2S and La2O2S are finding a wide range of luminescence applications but their solid-solution form has rarely been reported in the literature. A series of [(Gd1.0-xLax)0.99Pr0.01]2O2S (x = 0.0–1.0, GLOS:Pr3+) solid-solution phosphor nanopowders were directly produced in this work by calcining their sulfated hydroxide type precursors in flowing hydrogen at 900 °C, without using any of the harmful sulfidization reagents indispensable to other technical routes. The synthesis method also has the significant advantages of fine crystallites (∼20–35 nm), high specific surface area (∼16–21 m2/g) and unimodal particle size distribution (average particle size ∼120–140 nm) of the product. Photoluminescence study indicated that La3+ doping may remarkably enhance Pr3+ luminescence under 263 nm excitation, though tends to lower the thermal stability and elongate the lifetime of the emission. Aside from phosphor application, the thus-synthesized GLOS:Pr3+ powders would be well suited for the sintering of high-quality ceramic scintillators because of their fine particle/crystallite size and unimodal/narrow size distribution.

Spatial and seasonal variations of primary and secondary organic aerosols at urban areas and continental background site of China: Ambient levels, size distribution, and sources

Organic aerosols are important constituents of particulate matter (PM) in the atmosphere, however, the studies on their size distribution, particularly for special primary and secondary organic aerosols (POA, SOA), are relatively limited. In this work, the size-segregated PM was collected from five megacities (Shanghai, Guangzhou, Xi’an, Chengdu, Urumqi) and a continental background site (Qinghai Lake, Tibetan Plateau) of China during 2012–2014. Special POA (plant wax n-alkanes, fossil fuel n-alkanes, PAHs, levoglucosan, and trehalose) and biogenic SOA (BSOA, i.e. isoprene oxidants, monoterpene oxidants, and β-caryophyllenic acid) in PM were measured using gas chromatography/mass spectrometry. n-Alkanes were highest in autumn in the Southeast of China and highest in summer in the Northwest of China during the four seasons. PAHs and levoglucosan were higher in the cold season, mainly influenced by residential heating. Isoprene and monoterpene oxidants were higher in the warm season, while β-caryophyllenic acid was found to be much higher in cold seasons. n-Alkanes showed a monomodal distribution, with a peak at the fine mode (<1.1 µm). PAHs and levoglucosan were characterized by an accumulation mode, revealing the peak at <1.1 µm. However, only trehalosedisplayed coarse mode at the six sites, peaking at a size of 3.3–9.0 µm, because it was mostly derived frombiota in desert regions. Isoprene oxidants including 2-methylglyceric acid, 2-methyltetrols, and C5-alkene triols exhibited a unimodal size distribution pattern with a peak in the fine mode. Monoterpene oxidants such as cis-pinic acid, pinonic acid, 3-hydroxyglutaric acid, and 3-methyl-1,2,3-butanetricarboxylic acid exhibited a bimodal size distribution pattern in the whole sampling time, peaking at the size range of <1.1 µm and 3.3–9.0 µm, respectively. Only β-caryophyllenic acid displayed a fine mode at the six sites during the whole sampling time. These findings can be used to support research into the origin and formation mechanisms of POA and BSOA.

Textural characteristics of surficial sediments along the Noakhali coast, Bangladesh: An implication for mineral placer deposits exploration

This study aimed to explore mineral placer deposits analyzing textural characteristics; mean size (Mz), standard deviation (σi), skewness (Ski), kurtosis (KG), and the depositional environments of surficial sediments deposited in the Noakhali coast along the Meghna River estuary. A total of nine sediment samples were collected, and the textural parameters were analyzed by a laser particle size analyzer (Microtrac S3500). The mean size of the sediment samples ranged from 3.063 Φ to 5.11 Φ, where the seven samples exhibited sandy-silt texture and only two samples silty-sand texture. However, all the samples presented unimodal grain size distribution. A minimal amount of clay (0.12–1.4%) had been found in three samples collected from Urir Char Island. Higher values of standard deviation (4.15 Φ to 5.76 Φ) indicated extremely poorly sorted sediments. Skewness value varied from 0.107 to 0.510 expressed fine to very fine skewness, and kurtosis value from 0.1033 to 1.525 exhibited a mesokurtic to very leptokurtic nature of the sediments. These textural characteristics indicated a low to moderate energy deposition of finer (mostly silt), unidirectional, and riverine sediments. Linear discriminant analysis (LDA) results revealed the littoral, shallow marine, and fluvial deposition of the sediments. CM pattern showed the deposition of sediments by graded suspension without rolling and uniform suspension. Both of these processes indicated low to moderate energy deposition of sediments. As the majority of samples were silt dominated, there are very low prospects of finding valuable heavy minerals except two locations (SP-04, 06) where sand is dominated, and minerals placers could be found there. Low to moderate depositional environments also indicated fewer prospects of finding mineral placer deposits in the studied area.

Experimental and numerical investigations of plastic strain mechanisms of AISI 316L alloys with bimodal grain size distribution

In this article, the plastic strain mechanisms of AISI 316L with bimodal grain size distributions are investigated using experimental characterizations and numerical simulations. Using powder metallurgy routes, samples were first manufactured to obtain unimodal (both ultra-fine grained and coarse grained) and bimodal grain size distributions with different volume fractions of ultra-fine and coarse grain populations. These specimens were then studied mechanically by performing monotonic and loading–unloading tensile tests. Based on the numerical description of microstructures with similar characteristics than the experimental ones, full-field finite element analyses were also conducted using the Méric-Cailletaud crystal plasticity model modified to take into account a grain size strengthening. Using both experiments and simulations, deformation mechanisms were investigated. Results show that the grain size distribution greatly affects these mechanisms: both the long-range intergranular backstress and the distributions of stress and strain inside each grain population are modified. In particular, the formation of low stress channels and of localization shear bands expanding over tens of grains are observed. These modifications depend, however, on the volume fraction of each grain size population and on the spatial distribution of one with respect to the other. These results are then discussed in terms of grain population interactions, long range backstress and grain size contrast.

Supercritical CO2 assisted process for the production of mixed phospholipid nanoliposomes: Unloaded and vitamin D3-loaded vesicles

In this study, SuperLip, an innovative technology assisted by supercritical carbon dioxide (SC–CO2), was used to produce unloaded and vitamin D3 (VD3)-loaded nanoliposomes. Vesicles were produced using hydrogenated and nonhydrogenated phosphatidylcholine from food-grade lecithins at ratios of 30:70, 20:80 and 0:100. SuperLip was operated at 100 bar and 40 °C using water flow rates ranging from 2.5 to 10 mL/min. The results showed that unloaded liposomes produced by SuperLip presented a unimodal size distribution at a water flow rate of 10 mL/min, regardless of the phospholipid ratio, and mean diameters ranging from 125 to 141 nm. VD3-loaded liposomes also presented a unimodal size distribution at this water flow rate, but slightly higher diameters that ranged from 144 to 252 nm. Furthermore, the addition of 20% purified phospholipids to liposomes led to an increase in the mean size of VD3-loaded vesicles from 144 to 218 nm and an increase in the encapsulation efficiency from 66.7 to 88.9%.

Skin Regenerative Potential of Cupuaçu Seed Extract (Theobroma grandiflorum), a Native Fruit from the Amazon: Development of a Topical Formulation Based on Chitosan-Coated Nanocapsules.

Scarless skin regeneration is a challenge in regenerative medicine. Herein, we explore the regenerative potential of a Cupuaçu seed extract (Theobroma grandiflorum) to develop an innovative skin regeneration formulation based on chitosan-coated nanocapsules. Cupuaçu seed extract significantly stimulated cell proliferation and migration. A reparative gene expression profile could be verified following extract treatment, which included high levels of MKI67, a cellular proliferation marker, and extracellular matrix genes, such as ELN and HAS2, which code for elastin and hyaluronic acid synthase 2. Formulations with Cupuaçu seed extract successfully entrapped into nanocapsules (EE% > 94%) were developed. Uncoated or coated nanocapsules with low-molecular-weight chitosan presented unimodal size distribution with hydrodynamic diameters of 278.3 ± 5.0 nm (PDI = 0.18 ± 0.02) and 337.2 ± 2.1 nm (PDI = 0.27 ± 0.01), respectively. Both nanosystems were physically stable for at least 120 days and showed to be non-irritating to reconstructed human epidermis. Chitosan coating promoted active penetration into undamaged skin areas, which were still covered by the stratum corneum. In conclusion, the present study demonstrated for the first time the biotechnological potential of the frequently discarded Cupuaçu seed as a valuable pharmaceutical ingredient to be used in regenerative skin products.

Morphology of island structures formed by self-organization processes during melting of lead films

The paper presents the results of the study of the formation of arrays of metal particles arising due to the phenomenon of self-organization during melting of lead films. The lead films from 15 to 300 nm thickness were studied, condensed onto amorphous carbon substrates at room temperature. The excess energy of the initial film, which is the driving force of thermal dispergation, has been determined. It was found that the arrays of particles formed during the melting of lead films with a thickness of less than 150–200 nm have a unimodal size distribution. The existence of a critical mass thickness of the initial film has been found, at which the form of the size dependences of the coverage of the substrate with the film and the density of particles in the sample changes. The presence of the critical thickness is explained by a change in the morphological structure of the initial film at a given thickness.

Optically controlled dual-band quantum dot infrared photodetector

We present the design for a novel type of dual-band photodetector in the thermal infrared spectral range, the Optically Controlled Dual-band quantum dot Infrared Photodetector (OCDIP). This concept is based on a quantum dot ensemble with a unimodal size distribution, whose absorption spectrum can be controlled by optically injected carriers. An external pumping laser varies the electron density in the QDs, permitting to control the available electronic transitions and thus the absorption spectrum. We grew a test sample which we studied by AFM and photoluminescence. Based on the experimental data, we simulated the infrared absorption spectrum of the sample, which showed two absorption bands at 5.85 μm and 8.98 μm depending on the excitation power.

Synthesis of surface-modified iron oxide nanocrystals using supercritical carbon dioxide as the reaction field.

In the synthesis of surface-modified nanocrystals (NCs), a simple and green chemistry approach to reduce liquid waste, particularly a solventless process, has been desired. In this study, we applied the supercritical CO2 technology, which is an excellent solventless process, to the synthesis of surface-modified iron oxide NCs. The synthesis was performed at 30.0 ± 0.8 MPa of CO2, 18 h and 100 °C, where iron(iii) acetylacetonate, pure water and decanoic acid were used as starting materials. As a result, the supercritical CO2 medium gave the NCs of α-Fe2O3 and γ-Fe2O3 with unimodal size distribution, where the mean size was 7.8 ± 2.0 nm. In addition, they were self-assembled on the TEM substrate and the mean nearest-neighbor spacing was close to the chain length of decanoic acid. Furthermore, FT-IR and TG analyses indicate that decanoic acid chemically attaches to the surface of iron oxide NCs that are dispersed in cyclohexane. These results suggest that the supercritical CO2 medium could be the new appealing reaction field to fabricate densely modified NCs without liquid waste.

Textural Characteristics and Depositional Environment of Ngrayong Sandstone (Middle Miocene) from Rembang Area, Northeast Java, Indonesia

Granulometric analysis of Ngrayong sandstone samples from Rembang area of NE Java (Indonesia) has been carried out to examine the textural characteristics and elucidate depositional environment. The result data from the grain size analysis indicates that the Ngrayong sediments are classified as sand or muddy sands. They are very fine- to medium-grained (phi values: 1.67 to 3.35), moderately- to well-sorted (standard deviation: 0.19 to 0.57), strongly fine-skewed to strongly coarse-skewed (skewness values: 4.82 to −5.97), and very platykurtic to very leptokurtic (kurtosis values: 0.36 to 2.41). Sandstone samples show unimodal grain size distribution. The sediments are interpreted to be transported in all three modes-traction, saltation and suspension, however, suspension and rolling are the major processes during transportation. Discriminant functions indicate diversity in the depositional environment for the sandstones. However, shallow marine is regarded as the dominant depositional environment. The preponderance of fine-grained sediments and lack of coarse sands suggest low to moderate energy conditions during deposition of Ngrayong sediments.

Impact of Rain on Retrieved Warm Cloud Properties Using Visible and Near-Infrared Reflectances Using Markov Chain Monte Carlo Techniques

Estimates of cloud droplet effective radius ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">r_e</i> ) and optical thickness (τ) can be derived using reflected sunlight in a visible non-absorbing channel combined with reflectances from a near IR channel that is absorbing (e.g., The bi-spectral method or BSM). Discrepancies between BSM-estimated <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">r_e</i> and collocated in situ measurements are commonly attributed to a violation of the assumptions used in the BSM algorithm such as plane parallel geometry, and a single mode droplet size distribution. This research uses Markov Chain Monte Carlo experiments to examine the impact of precipitation on BSM-retrieved <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">r_e</i> near optical cloud top by comparing the retrievals and associated uncertainties obtained from two types of experiments assuming a unimodal or bimodal drop size distribution. Where rain is present, BSM-retrieved <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">r_e</i> overestimates the true cloud mode <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">r_e</i> . Moreover, there is no longer a unique measure of <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">r_e</i> within the precipitating liquid-phased clouds, resulting in a substantial increase in retrieval uncertainties. This leads to a corresponding loss of information on total number concentration and liquid water content near cloud top. It is found that <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">r_e</i> biases are not strongly correlated with properties exclusively pertaining to rain, such as rain water content or precipitation rates, but tend to be a function of the ratio between rain and cloud water content and the cloud total number concentration. These results highlight the need for additional independent information such as from an active or passive microwave sensor that can identify the presence of precipitation and constrain additional aspects of bimodal droplet distributions.

Size-resolved Compositional Analysis and Source Apportionment of Submicron Aerosol during Lockdown Period Using HR-ToF-AMS

The size-resolved compositional analysis of non-refractory submicron aerosol (NR-PM1) was conducted using the Aerodyne High-Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS) instrument over Pune, India during the COVID-19 lockdown period. The aerosol composition data shows the predominant presence of organics (Org) in the mass fraction followed by sulfate, ammonium, nitrate, and chloride during the pre-lockdown and lockdown periods. The size-resolved analysis showed the unimodal size distribution of organic and inorganic constituents with peaks at 550 nm, implying the dominant presence of mixed and aged aerosol species. The stoichiometric neutralization analysis showed the almost neutralized nature of submicron aerosol with an average aerosol neutralization ratio (ANR) of 0.8. The back trajectories, cluster analysis, and potential source contribution function (PSCF) showed the industrial belt located in the western part of the study location to be the potential source regions of NR-PM1. Positive matrix factorization (PMF) analyses have been applied to investigate the source apportionments of organic aerosols (OA). Four distinct OA factors, i.e., hydrocarbon-like OA (HOA), biomass burning OA (BBOA), low-volatile oxygenated OA (LVOOA), and semi-volatile oxygenated OA (SVOOA) were identified during the study period. Among these factors, HOA contributes nearly a quarter to the OA mass, and OOA accounted for nearly 60% of the total OA mass. The high-resolution positive matrix factorization (HR-PMF) analysis and the elemental ratios of H/C, O/C, and OM/OC showed distinct characteristics during different periods. The density of organic aerosol has been estimated using the elemental ratios and found to be 1.14, 1.28, and 1.35 respectively during the different lockdown periods, similar to 1.30 g/cm3 as mentioned in the literature. This study provides new insights into the chemical composition and source apportionment of the organic fraction of submicron aerosols for the first time over Pune using HR-ToF-AMS and HR-PMF.

Uncovering the symmetry of the induced ferroelectric phase transformation in polycrystalline barium titanate

Microstructural design is a widespread approach to tailor the properties of functional materials with the size effect being an effective constraint that modifies physical phenomena. In this work, we investigate the grain size effect on the properties and the electric field induced phase transformation behavior in barium titanate. A broad range of unimodal average grain size distribution between 0.4 and 15 μm was successfully sintered avoiding abnormal grain growth. Samples with a grain size close to the range of 1–2 μm, balancing microstructural strain, presence, and mobility of domain walls to allow the field induced crystal phase transformation, showed optimal electromechanical and dielectric properties. By means of in situ high energy x-ray diffraction and a high-resolution multianalyzer detector, we distinguish and quantify a tetragonal–orthorhombic phase transformation induced by an electric field, providing unambiguous proof of this induced phase transformation. These results contribute to the understanding of fundamental questions about the piezoelectric effect in barium titanate and consequently other similar systems.

PH-driven self-assembly of alcohol-free curcumin-loaded propylene glycol alginate nanoparticles

The purpose of this paper was to explore the application of propylene glycol alginate (PGA) alone in alcohol-free curcumin-loaded nanoparticles (PGA/Cur) prepared by a pH-driven method to solve the curcumin shortcomings of low water solubility, stability and bioavailability. One of the bright spots of PGA/Cur was its extremely high loading capacity. PGA/Cur formed a spherical structure mainly by hydrophobic interaction and hydrogen bonding, making curcumin amorphous. PGA/Cur exhibited stability at pH 4.0–8.0 due to its high surface charges. PGA/Cur still showed a unimodal size distribution even under 3000 mM ionic strength. Heating caused uneven size distribution, but the smaller size still presented its thermostability. PGA/Cur exhibited good physical stability and slowed down the curcumin degradation with t1/2 of 37.47 days during storage. PGA/Cur could maintain structural integrity in gastric acid and released curcumin in the intestine, thus improving the bioaccessibility of curcumin. Additionally, PGA/Cur displayed the solubilization after lyophilization.

Brake and tire particles measured from on-road vehicles: Effects of vehicle mass and braking intensity

Vehicle exhaust emissions have been decreasing due to stricter regulations and advancements in control strategies. However, non-exhaust emissions from brake and tire wear have not been extensively regulated in the past, and their relative contribution to particulate matter (PM) in urban areas is increasing. We examined the effect of a vehicle's mass and braking intensity on brake and tire particles based on on-road data collected from three different types of vehicles under real-world driving conditions. PM 2.5 and PM 10 concentrations and particle size distributions were measured near the center and rear of the right front wheel, respectively. During the braking, the highest peaks in brake PM 2.5 (520–4280 μg/m 3 ) and PM 10 (950–8420 μg/m 3 ) concentrations were observed from the heaviest vehicle, while the lowest peaks in brake PM 2.5 (250–2440 μg/m 3 ) and PM 10 (430–3890 μg/m 3 ) concentrations were observed from the lightest vehicle. Similarly, the observed peaks in tire PM 2.5 (340–4750 μg/m 3 ) and PM 10 (810–8290 μg/m 3 ) concentrations of the heaviest vehicle were shown to be the highest among the test vehicles, while the peaks in tire PM 2.5 (220–2150 μg/m 3 ) and PM 10 (370–3840 μg/m 3 ) concentrations of the lightest vehicle were lower than other vehicles. A statistically significant difference in the peak values of PM 2.5 and PM 10 concentrations was observed between the heaviest and lightest vehicles for both brake and tire particles. The braking deceleration rate was found to be an important factor in predicting the peaks in PM 2.5 and PM 10 concentrations during major braking events for all three test vehicles. Brake particles showed a unimodal mass size distribution with a mode diameter of 3–4 μm, while tire particles showed a slightly larger mode diameter of 4–5 μm. The finding of this study provides insight into the effects of driving conditions and vehicle mass on brake and tire emissions. • Brake and tire particles were measured from three vehicles tested on-road. • Heavier vehicles emit higher levels of brake and tire particles. • Heavy braking can lead to elevated brake and tire PM concentrations.

Bimodal particle distributions with increased thermal conductivity for solid particles as heat transfer media and storage materials

Solid particles are being considered in several high temperature thermal energy storage systems and as heat transfer media in a variety of advanced power generation systems, particularly in concentrated solar power plants. The downside of such an approach is the low overall heat transfer coefficients caused by the inherently low thermal conductivity values of the low-cost solid media when coupled to heat exchanger for the power cycle working fluid. Choosing the right particle size distribution, emittance, and material of the solid media can all make a substantial difference in packed bed thermal conductivity. Current research though exclusively focuses on continuous unimodal distributions of particles. Here, we propose the use of a binary particle system with a bimodal size distribution to significantly increase packed bed thermal conductivity by reducing packed bed porosity. This is the first study related to ceramic solid particle heat transfer that has considered the thermal conductivity of non-unimodal size distributions at room and elevated temperatures. The following study found that for the binary particle system using Carbo particles CP 16/30 – CP 70/140 where the large particle volume fraction was 50% there was an 17–47% increase in packed bed thermal conductivity when compared with a nearly unimodal particle size distribution of CP 16/30 between 50 and 300 °C. Two different porosity and effective thermal conductivity models were studied, with one providing better prediction of porosity but both effective thermal conductivity models providing less predictive capacity. Importantly this approach can have a substantial impact of thermal performance, with little to no impact on the particle cost.

Synthesis of nanomaterials by electrode erosion using discharges in liquids

Discharges in liquids are very efficient to synthesize nanoparticles by electrode erosion. This simple process is only simple in appearance. Mechanisms responsible for the production of nanoparticles are several depending on the choice of process parameters. They determine size distributions, shapes, composition, and defects of produced particles. They also control their possible assembly into more complex structures. This article describes the basic physics of nanoparticles’ synthesis by discharges in liquids using electrodes and gives a summary of the research efforts that have been devoted to the understanding of this process. A special attention is paid to thermodynamics of these systems driven by discharges that are at or close to local equilibrium. Although a complete picture is not available yet, huge progress has been made and offers new capabilities for a better control of these kinds of processes. Finally, among important challenges that are still to tackle, the possibility of forming nanoalloys from immiscible elements or achieving unimodal monodisperse size distributions is questioned from the current mastery reached in this field.

Bubble characteristics in subcooled flow boiling of seawater

Bubble characteristics are important to the two-phase flow dynamics and two-phase flow simulation. Different from the known slug flow in subcooled flow boiling of de-ionized water, fined bubbly flow and foam flow are found to be dominant in that of artificial seawater at high temperatures. Through image analysis, the present study conducts bubble characteristics measurements of such bubbly/foam flow of subcooled flow boiling in artificial seawater, including bubble Sauter mean diameters, bubble equivalent diameters and distributions of bubble sizes, bubble shapes and bubble orientations. The data set is compared with that in de-ionized water. The images for analysis are acquired from the high-speed camera with 4000 frame/s. The results indicate the Sauter mean diameters of de-ionized water could be larger than that of artificial seawater by 16–30%. Good agreements with two existing correlations prove the accuracy of current measurements and provide a way to predict the bubble characteristic in such fined bubble systems. Moreover, the results reveal the two-phase foam flow structure in artificial seawater is comparatively rigid and inflexible, compared to that in the de-ionized water. Increasing liquid temperature to 85℃ may keep the Sauter mean diameter of bubbles in artificial seawater at a stable value. The only peak of the unimodal bubble size distributions of artificial seawater is at 0.15–0.36 mm, while the possible other peak of bimodal bubble size distributions of de-ionized water is at 0.78–0.99 mm or 0.57–0.78 mm. Bubbles are mostly either nearly/perfectly parallel to the heated surface or perpendicular to the heated surface. Spherical shape for bubbles smaller than 0.2–0.25 mm, rigid ellipsoid shape for intermediate bubbles with diameter greater than 0.40 mm and less than 1.0 mm −2.7 mm, and distorted large bubbles, depending strongly on the liquid temperature, are observed. The data of bubble aspect ratio appear to be quite scattering due to the complicated nature of subcooled flow boiling. However, its general variation trend with Eötvös number or the product of Eötvös number and vapor Reynolds number agrees fairly well with some well-known correlations in the literature. Moreover, the bubble shape can also be predicted well with an extrapolated boundary of the Grace diagram on the plane of gas Reynolds number versus Eötvös number.

Alginate Nanohydrogels as a Biocompatible Platform for the Controlled Release of a Hydrophilic Herbicide

The large-scale application of volatile and highly water-soluble pesticides to guarantee crop production can often have negative impacts on the environment. The main loss pathways are vapor drift, direct volatilization, or leaching of the active substances. Consequently, the pesticide can either accumulate and/or undergo physicochemical transformations in the soil. In this scenario, we synthesized alginate nanoparticles using an inverse miniemulsion template in sunflower oil and successfully used them to encapsulate a hydrophilic herbicide, i.e., dicamba. The formulation and process conditions were adjusted to obtain a unimodal size distribution of nanohydrogels of about 20 nm. The loading of the nanoparticles with dicamba did not affect the nanohydrogel size nor the particle stability. The release of dicamba from the nanohydrogels was also tested: the alginate nanoparticles promoted the sustained and prolonged release of dicamba over ten days, demonstrating the potential of our preparation method to be employed for field application. The encapsulation of hydrophilic compounds inside our alginate nanoparticles could enable a more efficient use of pesticides, minimizing losses and thus environmental spreading. The use of biocompatible materials (alginate, sunflower oil) also guarantees the absence of toxic additives in the formulation.

Comparison of SEM-Assisted Nanoporometric and Microporometric Morphometric Techniques Applied for the Ultramicroporous Polymer Films

One of the most important applications of polymeric porous nanomaterials is the design of nanoporous structures for operation in patch-clamp systems allowing to establish a gigaohm contact, as well as for the measurements of biomolecules, informational macromolecules, including DNA, translocating through the nanopore arrays. Development of nanopore sequencing techniques leads to fundamentally new big data arrays, but their representativeness and validity, as well as the validity of counting of biomacromolecular particles based on ultramicropore arrays, strongly depends both on the pore size (in engineering lithography unimodal pore size distribution is optimal) and the accuracy of the size distribution measurements using instrumental methods. However, the former is unattainable when using soft matter or stretchable, plastic and elastic polymer materials and films, while the latter depends on the metrological parameters of the instrumental and algorithmic porosimetry techniques. Therefore in this paper the question about the applicability of polymer materials with pore arrays for the studies of biomacromolecules and bionanostructures is proposed to be answered using a comparative analysis of two different porosimetry approaches with the resolution not lower than electron microscopic one.