Content In Particles Research Articles

О КИСЛОТНОСТИ АЭРОЗОЛЬНЫХ ЧАСТИЦ В АТМОСФЕРЕ В ФОНОВЫХ УСЛОВИЯХ

Estimates for the acidity of aerosol particles in the rural atmosphere over Wingene (Belgium) are presented. The results of processing monitoring data using data of the control of meteorological conditions, gas impurities, ion composition, and mass concentration of aerosol particles, as well as the use of thermodynamic methods showed that the level of acidity of aerosol particles in the atmosphere is unexpectedly high (pH ≈ 3.5-4.3) despite their sampling in the background area. It is found that the variability of particle acidity is mainly determined by fluctuations in relative humidity and the content of gas-phase ammonia in the air. In this case, the lower the relative humidity is, the higher the acidity of particles is, which reflects the variability of moisture content in particles and the solubility of ammonium nitrate.

Visualization of Combustion Phases of Biomass Particles: Effects of Fuel Properties.

This work established a high-speed camera-assisted visualization system that investigated the effect of volatile matter and fixed carbon content in biomass particles on single-particle combustion phases and their luminous properties. Three types of biomass particles, namely, sawdust (a mixture of pine and willow), corncob, and rice husk, were examined on a Hencken flat-flame burner. The luminous region and intensity of single biomass particles were closely related to the flammability and calorific value of biomass fuel and derived by analyzing a sequence of images captured using a high-speed camera. The combustion temperature was determined through analysis of its radiant energy. The results showed that the ignition mechanisms of volatile matter and fixed carbon corresponded to homogeneous and heterogeneous reactions, respectively. The maximum luminous region values of 1.75 × 106, 2.1 × 106, and 1.0 × 106 μm2 for sawdust (SD), corncob (CC), and rice husk (RH) correlated to the volatile matter content of each biomass sample, which was 69.38, 74.15, and 64.56%, respectively. Because of the high fixed carbon content, the peak temperature of the SD particles could reach 1549 °C. The luminous region and intensity of the combusting particles were significantly affected by the volatile matter and fixed carbon, respectively.

Black Carbon Involved Photochemistry Enhances the Formation of Sulfate in the Ambient Atmosphere: Evidence From In Situ Individual Particle Investigation

AbstractMixing state of black carbon (BC) with secondary species has been highlighted as a major uncertainty in assessing its radiative forcing. While recent laboratory simulation has demonstrated that BC could serve as a catalyst to enhance the formation of sulfate, its role in the formation and evolution of secondary aerosols in the real atmosphere remains poorly understood. In the present study, the mixing of BC with sulfate/nitrate in the atmosphere of Guangzhou (China) was directly investigated with a single particle aerosol mass spectrometer (SPAMS). The peak area ratios of sulfate to nitrate (SNRs) for the BC‐containing particles are constantly higher than those of the BC‐free particles (defined as particles with negligible BC signals). Furthermore, the seasonal SNR peak is observed in summer and autumn, and the diurnal peak is found in the afternoon, consistent with the trends of radiation‐related parameters (i.e., solar radiation and temperature), pointing to the BC‐induced photochemical production of sulfate. Such hypothesis is further supported by the multilinear regression and random forest analysis, showing that the variation of SNRs associated with the BC‐containing particles could be well explained (R2 = ∼0.7–0.8) by the radiation‐related parameters (>30% of the variance) and the relative BC content (∼20%) in individual particles, but with limited influence of precursors (SO2/NOx: <5%). Differently, the radiation‐related factors only explain <10% of the SNR variation for the BC‐free particles. These results provide ambient observational evidence pointing to a unique role of BC on the photochemical formation and evolution of sulfate, which merits further quantitative evaluations.

Impact of CuO nanoparticles on maize: Comparison with CuO bulk particles with special reference to oxidative stress damages and antioxidant defense status

The present study aimed to systematically investigate the particle size effects of copper (II) oxide [CuO nanoparticles (<50 nm) and CuO bulk particles (<10 μm)] on maize (Zea mays L.). Bioaccumulation of Cu, in vivo ROS generation, membrane damage, transcriptional modulation of antioxidant genes, cellular redox status of glutathione and ascorbate pool, expression patterns of COPPER TRANSPORTER 4 and stress responsive miRNAs (miR398a, miR171b, miR159f-3p) with their targets were investigated for better understanding of the underlying mechanisms and the extent of CuO nanoparticles and CuO bulk particles induced oxidative stress damages. More restricted seedling growth, comparatively higher membrane injury, marked decline in the levels of chlorophylls and carotenoids and severe oxidative burst were evident in CuO bulk particles challenged leaves. Dihydroethidium and CM-H2DCFDA staining further supported elevated reactive oxygen species generation in CuO bulk particles stressed roots. CuO bulk particles exposed seedlings accumulated much higher amount of Cu in roots as compared to CuO nanoparticles stressed plants with low root-to-shoot Cu translocation. Moderately high GR expression with maintenance of a steady GSH-GSSG ratio in CuO nanoparticles challenged leaves might be accountable for their rather improved performance under stressed condition. miR171b-mediated enhanced expression of SCARECROW 6 might participate in the marked decline of chlorophyll content in CuO bulk particles exposed leaves. Ineffective recycling of AsA pool is another decisive feature of inadequate performance of CuO bulk particles stressed seedlings in combating oxidative stress damages. Taken together, our findings revealed that toxicity of CuO bulk particles was higher than CuO nanoparticles and the adverse effects of CuO bulk particles on maize seedlings might be due to higher Cu ions dissolution.

Formation mechanism and magnetic performance of Fe-Si soft magnetic composites coated with MnO-SiO2 composite coatings

Fe-Si soft magnetic composites (SMCs) coated with MnO-SiO2 composite coatings were fabricated via sintering the ball milled Fe-Si/MnO2 composite powders. The transformation mechanism from MnO2 coating to MnO-SiO2 composite coatings was studied. The effect of MnO2 content on the microstructure and magnetic properties of Fe-Si soft magnetic composites has also been investigated systematically. The analysis results indicated that MnO2 would be reduced to MnO by Si in the Fe-Si particles at 780.1 ℃. When the temperature reached 985.8 ℃, the generated MnO and SiO2 would further combine to form 2MnO·SiO2, finally forming the MnO-SiO2 composite coatings. With the increase of the MnO2 content from 0.0 wt% to 10.0 wt%, the MnO-SiO2 composite coatings became thicker, thus the saturation magnetization and permeability decreased gradually. However, exorbitant MnO2 content above 5.0 wt% would result in excessive in-situ Fe existed in the composite coatings and obvious reduction of Si content in the Fe-Si particles due to the above solid-state reactions. Therefore, the increasing trend of the resistivity was weakened. And the 5.0 wt% MnO2 coated Fe-Si SMCs exhibited superior comprehensive performance such as high saturation magnetization (186.5 A·m2/kg), good permeability (71), low total core loss (362.6 mW/cm3 at 50 kHz).

A predictive model of synergetic particulate-SO3 removal in ultralow cold-side electrostatic precipitators

In this paper, a comprehensive predictive model is established for the synergetic removal of fine particulate matter (PM) and SO3 in the ultralow cold-side electrostatic precipitator (ESP). Based on the population balance model framework, the current model incorporates SO3 condensation and coagulation in the low temperature economizer (LTE), as well as the quasi-1D dynamics of particle charging, migration, resuspension and deposition in the multi-staged ESP. Simplifications are made so that the resulting model can serve as a convenient software tool aiding the design and operation evaluation of the ultralow cold-side ESP. The model is validated against measurements of two coal-fired units with varied LTE outlet temperatures. In all cases, the predicted PM and SO3 emissions escaping the ESP agree well with the test data, and the relative errors are less than 17%. Quantitatively, running LTE removes ~60% of ultrafine PM0.1, and 80–95% of SO3 condense onto the preexisting fly ash in the LTE, resulting in a dp−2 -dependence of sulfur content in the size-segregated ash particles. Notably, the emitted PM1, PM10 and SO3 concentrations are largely reduced with lower LTE outlet temperatures; however, this promoting effect becomes marginal if further reducing the LTE outlet temperature under 100 °C. Finally, we conclude from a parametric analysis that the most important factor in the ultralow cold-side ESP is the flow residence time in the ESP, followed by the effects of intensified coagulation and elevated ash permittivity.

Apatite content and distribution in organic-rich particles

X-ray computed tomography (CT) can be used to generate 3D models of physical structures, but there is no explicit chemical or mineral information in a CT dataset. An image registration method is described here that uses CT and scanning electron microscopy with energy dispersive X-ray (SEM-EDX) to measure the volume of the apatite-bearing phase, φP, and the local variations in apatite concentration, CA, in individual low-grade apatite-ore particles. This method also permits a calculation of the apatite mass fraction, wA (from φP and CA), in individual particles, which effectively reconciles the X-ray signal to apatite grade. It was found that wA varied between 11 and 65 wt. % in individual particles, compared to the apatite content (51 wt. % by X-ray diffraction) of the bulk sample, which indicates the low-grade apatite ore studied was a mixture of high- and low-grade particles. This study establishes a clear link between the X-ray CT signal, grade distribution, and the qualitative description of the apatite-bearing phase morphology within single particles. Process options for this ore, with further study, could be based on the selective removal, or pre-concentration, of low-grade coarse particles before they enter the comminution circuit.

Intrinsic Li Distribution in Layered Transition-Metal Oxides Using Low-Dose Scanning Transmission Electron Microscopy and Spectroscopy

Understanding Li distribution in layered lithium transition-metal oxide (LiTMO) cathodes in Li-ion batteries has been a major challenge at the atomic scale and nanoscale. Li is extremely difficult to study by transmission electron microscopy (TEM) because the high-energy electrons impart significant energy and cause massive migration. Here, we directly map the intrinsic spatial distribution and bonding of Li in LiNiO2-layered cathode materials using low-dose and low-loss electron energy loss spectroscopy (EELS). EELS spectra of the Li–K edge are measured simultaneously with O–K and Ni–L, M3,2 edges from layered, cation-mixed, and rock-salt phases and directly matched with atomic-resolution scanning TEM images to correlate the changes in peak intensities and positions to the stoichiometry changes with continual loss of Li and O. Changes in the Li content in the LiNiO2 particles as a function of electron beam dose are studied by sequential Li spectroscopic mapping. We show that the “intrinsic” Li distribution can be observed using a total dose of less than ∼1.5 × 108 e– nm–2 at an accelerating voltage of 80 kV. The method of nanoscale mapping of Li distribution introduced in this study is applicable to high-Ni LiTMO cathode materials (>89% of Ni) as well as LiNiO2. Further study on the extra peaks of the Li–K edge reveals that the peak at ∼59 eV is from the Li ions intercalated in between NiO2 layers barely interacting with each other with less Li K shell electrons pulled to the L shell electrons in NiO2. The results shown here provide improved low-loss TEM characterization approaches that can be used to understand the intrinsic fundamental behaviors in Li-ion batteries.

Are standardized diesel exhaust particles (DEP) representative of ambient particles in air pollution toxicological studies?

In this study, we investigated the chemical characteristics of standardized diesel exhaust particles (DEP) and compared them to those of read-world particulate matter (PM) collected in different urban settings to evaluate the extent to which standardized DEPs can represent ambient particles for use in toxicological studies. Standard reference material SRM-2975 was obtained from the National Institute of Standards and Technology (NIST) and was chemically analyzed for the content of elemental carbon (EC), organic carbon (OC), polycyclic aromatic hydrocarbons (PAHs), inorganic ions, and several metals and trace elements. The analysis on the filter-collected DEP sample revealed very high levels of EC (i.e., ~397 ng/μg PM) which were comparable to the OC content (~405 ng/μg PM). This is in contrast with the carbonaceous content in the emitted particles from typical filter-equipped diesel-powered vehicles, in which low levels of EC emissions were observed. Furthermore, the EC mass fraction of the DEP sample did not match the observed levels in the ambient PM of multiple US urban areas, including Los Angeles (8%), Houston (~14%), Pittsburgh (~12%), and New York (~17%). Our results illustrated the lack of several high molecular weight carcinogenic PAHs in the DEP samples, unlike our measurements in major freeways of Los Angeles. Negligible levels of inorganic ions were observed in the sample and the DEP did not contain toxic secondary organic aerosols (SOAs) formed through synchronized reactions in the atmosphere. Lastly, the analysis of redox-active metals and trace elements demonstrated that the levels of many species including vehicle emission tracers (e.g., Ba, Ti, Mn, Fe) on Los Angeles roadways were almost 20 times greater than those in the DEP sample. Based on the abovementioned inconsistencies between the chemical composition of the DEP sample and those of real-world PM measured and recorded in different conditions, we conclude that the standardized DEPs are not suitable representatives of traffic emissions nor typical ambient PM to be used in toxicological studies.

Size effect of zircon particles in brake pads on the composition and size distribution of emitted particulate matter

Particulate matter (PM) emitted during brake application is investigated, focusing on the size effect of zircon particles in brake pads. The results show that the concentration, size distribution, and composition of PM are strongly influenced by the size of the zircon particles. The iron content in ultrafine particles was higher when small zircon particles were used in the pad, whereas coarse zircon particles produced high iron content in the larger wear particles, suggesting that the amount and chemistry of the brake-induced PM are governed by different wear mechanisms at the sliding interface, which depend on the abrasive size.

Multi-scale stabilization mechanism of pickering emulsion gels based on dihydromyricetin/high-amylose corn starch composite particles

For Pickering emulsifying effect, starch must be subjected to the pretreatments of acid hydrolysis, esterification, which are complicated and eco-unfriendly. In this study, a practical and green strategyto fabricate Pickering emulsion gels with dihydromyricetin (DMY)/high-amylose corn starch (HCS) composite particles was introduced for the first time. The DMY content in composite particles and the amount of addition of composite particles had obvious synergistic effect on the formation and properties of emulsion gels. The obtained emulsion gels were not sensitive to ionic strength, which could be attributed to emulsifying capacity and viscosity effect of composite particles. The spectral analysis confirmed the presence of DMY/amylose host-guest supramolecules. The molecular simulation of the supramolecular complexes in the oil-water system indicated that these complexes could spontaneously aggregate and anchor to the oil-water interface, reducing the interfacial tension. Based on experimental and theoretical results, the multi-scale relationship of “molecular interaction–particle characteristics–gel properties” was established.

Particulate Mercury and Particulate Organic Matter in the Itenez Basin (Bolivia)

In rivers and other freshwater bodies, the presence of mercury can be due to direct contamination by anthropic activities such as gold mining. However, it can also be attributed to atmospheric deposition and erosion, runoff, or lixiviation from surrounding soils. In the case of the Amazon rainforest, high mercury contents have been reported for litter and topsoil, which could affect the mercury concentrations in water bodies. Samples of suspended particulate matter were obtained from a transect of the Itenez River, associated lakes, and some of its tributaries. The aim was to obtain information on particulate mercury’s origin in the study area and determine the relationship between particulate mercury and particulate organic carbon. The concentration of mercury, organic matter, and the C:N ratio of the suspended matter was determined. The concentration of particulate mercury by water volume depended on changes in suspended matter loads, which in turn were mostly affected by the nature of the watershed or sediment resuspension. The observed values for the percentage of organic matter and the C:N ratio suggest that most of the mercury content in rivers and lakes originated from soils. A positive correlation was found between mercury concentration by weight of particulate matter and organic carbon content in particles. This correlation might be due to the direct binding of mercury to organic matter through functional groups like thiols or to an indirect effect of oxyhydroxides that can adsorb mercury and are associated with organic matter.

Analysis of terahertz wave attenuated by sand and dust storms with different modes

The research on space transmission characteristics of terahertz wave is of great significance for the application of terahertz wave in space. In order to study the transmission characteristics of terahertz wave in sand and dust storm weather, according to the lognormal distribution of dust particle sizes, Mie scattering theory and Monte Carlo method are used to analyze the attenuation characteristics of six dry sand modes of sand and dust storm in different regions of China in a frequency band of 1–10 THz, and the relationship of the extinction parameters and attenuation rate to the frequency is given. The results show that with the increase of frequency, the attenuation rate of 1–10 THz terahertz wave first increases and then decreases. Different mode of sand and dust storm leads to different frequency range of strong attenuation of terahertz wave. In order to analyze the influence of sand dust particle moisture content on terahertz wave propagation attenuation, the relationship of three efficiency factors to water content of sand dust particles with different sizes is calculated. The results show that the influence of water content on extinction is different from that of the particle size. Monte Carlo method is used to calculate the attenuation of terahertz wave by sand and dust storm in two kinds of wet sand modes, and the relationship of the attenuation rate and water content to the frequency is given, the results are compared with those from the dry sand mode, showing that the albedo of wet sand mode is obviously lower than that of dry sand mode with the same size distribution. The absorption of wet sand particles increases with water content increasing. The extinction of wet sand and dust storm results from scattering and absorption. With the increase of water content in sand particles, the frequency band with strong attenuation of terahertz wave by wet sand and dust storm moves toward low frequency. When the water content is less than 5%, the attenuation rate of terahertz wave increases significantly with the increase of water content. Sand and dust storms with higher humidity have a greater influence on the transmission attenuation of terahertz wave.

Plasma-based technique applied to the determination of 21 elements in ten size fractions of atmospheric aerosols

A study was undertaken to quantify metals and metalloids content in size-resolved atmospheric particles sampled in the megacity of Buenos Aires, Argentina. Ten size distributed aerosol with aerodynamic diameters of <0.10, 0.10–0.18, 0.18–0.32, 0.32–0.56, 0.56–1.0, 1.0–1.8 1.8–3.2, 3.2–5.6, 5.6–10 and 10–18 μm collected on Teflon filters by using a micro-orifice uniform deposition impactor (NanoMOUDI sampler) were analyzed. An acid mixture containing HCl, HNO3 and HF (6:2:1) was used for microwave (MW) assisted digestion of each airborne particulate matter (APM) fraction. Twenty-one elements namely, As, Ba, Be, Ca, Cd, Co, Cr, Cu, Fe, Hg, Li, Mg, Mn, Mo, Ni, Pb, Sb, Se, Ti, V and Zn were determined by plasma-based techniques namely inductively coupled plasma optical emission spectrometry (ICP OES) and inductively coupled plasma mass spectrometry (ICP-MS) in the digested size-distributed aerosols. A predominance contribution (~60%) of fine particle (PM1) was observed in the total aerosol mass. Mass size distribution together with Cu, Li and V exhibited bimodal distribution at 0.32–0.56 and 1.8–3.2 µm ranges. Eleven elements exhibited unimodal distributions with rock forming elements (Ca, Fe, Mg, Ti) and Ba peaking at 1.8–3.2 µm while As, Cd, Pb, Sb, Se and Zn peaking at 0.32–0.56 µm. These results are in line with findings from other cities which indicate that mineral dust has a higher contribution in the coarser fraction, while particles from fuel combustion and other traffic-related emissions are more relevant in the finer fraction.

Micro-analyses of dust particles generated in the JET tokamak with the ITER-like wall

Dust generated in JET with the ITER-like wall (ILW) was collected from the divertor by vacuum cleaning and examined with ion and electron beam methods. From totally 1 g retrieved after the third ILW campaign (2015–2016) a number of specimens were prepared using sticky (adhesive) carbon tabs. The aim was to determine the distribution and amounts of constituents: from deuterium (D) to W with particular emphasis on the concentration ratio of D to other species. Two classes of particles containing deuterium were identified: (i) rich in Be and (ii) low-Z matrix without Be, that show large C concentrations with some O contribution and minor contributions from heavier elements. The D content in Be-based particles has been at the level not exceeding ≈2 at %, whereas in the C-rich particles, both in small (10–100 µm) and large conglomerates (>100 µm), the D contribution at the level of about 15 to 20 at % has been detected. W-rich particles are often accompanied by Ni, Cr and Fe and occasionally with Mo. The results clearly indicate that fuel retention in the ILW dust is predominantly associated with residual C, approximately 10–20 times greater retention was found in C-rich objects than in metal-based particles.

Production of ultrafine-grained spherical β-WC-W2C-Co microparticles by electro discharge erosion of WC-15Co alloy in glycerol and their solutions

The present work is devoted to the study of the production of ultrafine-grained (UFG) spherical microparticles by electro discharge erosion (EDE) of the WC-15Co cemented carbide in glycerol, distilled water, and their solutions. Energy costs, productivity, particle size distribution, and morphological and chemical compositions of the obtained powders were studied. It was found that energy cost is reduced by 2.2 times when glycerol was used instead of water. The use of water reduces carbon content from 5.2% to 1.4%. The use of glycerol and its aqueous solutions reduces carbon loss and increases its content in the obtained powders from 3.2% to 6.1%. During SE, cobalt, carbon, and tungsten evaporate from spherical particles and crystallize in the form of ultrafine particles, which subsequently remain in suspension after sedimentation of spherical particles. Mass fractions of sedimented spherical particle fractions ranged from 75% to 82%. Cobalt and carbon content in the spherical particles obtained in glycerol decrease from 15% to 10% and from 5.2% t to 3.1% respectively. The particles consist of rounded carbide grains (β-WC and W2C) with a diameter of up to 500 nm, the space between which is filled with cobalt. Microhardness of the particles increased from 12.1 GPa (initial alloy) to 15.6 (EDE in water)—23.7 GPa (EDE in glycerol).

Combined effect of Y2O3 nanoparticles and Si second-phase oxide on microstructure and wear resistance of plasma-clad steel coating

Alloy steel 17Cr2NiSiMo coatings with small amounts (<1 wt%) of added Y2O3 nanoparticles are fabricated by plasma-transferred arc. The combined effect of the Y2O3 nanoparticles and Si-oxide second-phase particles on microstructure, sliding wear resistance, and wear weight loss of the alloy steel coating are investigated. The Y content in the spherical Si-oxide particles is found to increase with the addition of Y2O3 nanoparticles, as Si provides second-phase oxide particles for Y to accumulate in the coating material during the rapid cooling solidification. Thus, the Fe-based coating is refined and purified, resulting in a low defect or slag concentration. The wear mechanism of the modified coating transforms from third-body interaction and plastic deformation to slight peeling, as dendritic grains in the coating are transformed into equiaxed grains. The wear performance of the modified coating is obviously enhanced with the addition of 0.4 wt% Y2O3 nanoparticles, as indicated by the reduction of its wear weight loss to 20.55% and increase of its relative wear resistance to 25.87%.

Evaluation of the diffusional coefficient in the acid baking process using microwave energy to reduce phosphorus content in iron ore particles

The reduction in phosphorus content using microwave energy as a heating source has recently received remarkable attention due to the possibility of high heating rates and fracture generation in the particles. Such advantages can lead to a potential increase in productivity in the process of reducing the phosphorus content of iron ore particles, thereby increasing the reuse of large volumes of sterile with a high phosphorus content. Thus, it is highly relevant to understand how the interaction between the phosphate structure and the reaction medium occurs. Thus, this paper deals with the study of a possible kinetic model aiming at the process of reducing the phosphorus content using microwave energy to heat iron ore particles in contact with concentrated sulfuric acid (acid baking).This model treats the microwave oven as a multiphase reactor and two phases are considered simultaneously: liquid and granular or fine solids (crude or comminuted iron ore). First, a basic case consists of the ore/sulfuric acid mixture, in a ratio of 2:1. After heating, the mixture is added to a specific volume of water and then the system is stirred at a speed of 620 rpm. After the leaching process, the liquid was filtered and taken for chemical analysis, which was performed using an ultraviolet spectrometer at a wavelength of 420 nm for phosphorus and 473 nm for iron. Through the scanning electron microscopy (SEM) technique, it was possible to observe the structure of the iron ore particles after their treatment with microwave energy and leaching. Kinetic models of diffusional and chemical control were used to understand the interaction phenomena of sulfuric acid inside the particles. The mixed control kinetic model was also evaluated, in which it was possible to evaluate different parameters regarding the interaction between mineral structure and sulfuric acid as leaching medium. The obtained results indicated that the developed process has relevant utility. The kinetic modeling results contribute to a better understanding of heating phenomena using microwave energy, and also to the development of new cleaner technologies to improve the efficiency of the acid baking/leaching process to reduce particulate phosphorus content in iron ores.

Environmental Distribution of Styrene Oligomers (SOs) Coupled with Their Source Characteristics: Tracing the Origin of SOs in the Environment

Despite growing concerns regarding plastic additives, their environmental fate coupled with leaching from source materials are not well known. Styrene oligomers (SOs), which are unintended additives in expanded polystyrene (EPS), are estrogenic micropollutants. Here, we identified the effects of their potential sources (i.e., EPS buoy and its leachate) and environmental dilution on SO distribution within coastal sediments. SO content in fresh EPS particles was 0.1% (w/w), dominated by 2,4,6-triphenyl-hexene (ST-1), while 2,4-diphenyl-1-butene (SD-2) accounted for most of the SOs in EPS leachate, indicating its faster leachability. In lake and offshore environments, the SO composition profiles from their terrestrial inputs and inner sites were similar to those of EPS leachate; meanwhile, the exponentially decreasing SO concentration and increasing styrene trimers (STs) fraction with distance from the inner to outer sites were evident. These profiles indicated continuous SO leaching from their potential sources in the inland, followed by a change in SOs due to environmental dilution. SOs in beach sediment implied the presence of micro-sized EPS particles. We suggest the ST-1 to SD-2 ratio as an index to differentiate among freshly leached SOs (∼0.02), environmentally diluted SOs after leaching (∼0.1), SOs in fresh EPS (∼1.2), and SOs in aged EPS (> 2).

Physicochemical and Biological Properties of a Nanostructured IR-Photosensitizer Based on Dipropoxybacteriopurpurinimide

The production technology for nanoparticles based on a copolymer of lactic and glycolic acids (PLGA) containing dipropoxybacteriopurpurinimide (DPBPI) and intended for photodynamic therapy of malignant neoplasms of various etiology is optimized. An approach to reducing the average diameter of the resulting nanoparticles is proposed. The obtained DPBPI-PLGA nanoparticles had average diameter 142.3 ± 2.7 nm; ξ-potential 17.1 ± 3.42 mV; polydispersity index 0.095; and total DPBPI content in DPBPI-PLGA particles 17.4 mg/g. DPBPI-PLGA nanoparticles were produced for biological tests. The intracellular distribution of DPBPI in DPBPI-PLGA nanoparticles was studied in in vitro experiments on A549 cells. DPBPI accumulation kinetics in and elimination kinetics from the cells were also studied. DPBPI-PLGA showed high photoinduced cytotoxicity in in vitro experiments. DPBPI-PLGA nanoparticles exhibited antitumor activity in in vivo experiments in an S37 murine soft tissue sarcoma model.