Microbiome Development of Seawater-Incubated Pre-production Plastic Pellets Reveals Distinct and Predictive Community Compositions

Plastics of various chemistries pollute global water bodies. Toxic chemicals leach with detrimental and often unpredictable impacts on the surrounding ecosystems. We found that seawater leachates of plastic pre-production pellets from 7 recycle categories are acutely toxic to stage II barnacle nauplii; lethal concentration 50 (LC50s) were observed in 24-h leachates from dilutions ranging from 0.007 to 2.1 mg/mL of seawater. Based on previous observations that macro-organismal settlement on fouling management coatings of various toxicities can be used to predict the toxicity of the coating, we hypothesized that interaction of plastic pre-production pellets with emerging microbiomes would exhibit patterns indicative of the chemistry at the pellet surface. We used amplicon sequencing of bacterial 16S ribosomal RNA genes to characterize the microbiomes that developed from 8 through 70 days on pellets exposed to the same flowing ambient seawater. Diversity and composition of the microbiomes colonizing plastic pellets changed over time and varied with plastic type. Microbial taxa belong to taxonomic groups known to consume hydrocarbons, to be prevalent following marine oil spills, or to live on fouling management surfaces. Microbiomes were still distinct between plastic types at Day 70, suggesting that differences in the physicochemical characteristics of the underlying plastics continue to exert variable selection of surface microbial communities. A random forest-based sample classifier correctly predicted 93% of plastic types using microbiome compositions. Surface microbiomes have promise for use in forensically identifying plastic types and potential toxicities.

3-Dimensional Multiphysics Modeling of Behaviors of Pressurized Water Reactor Fuel Rods With Missing Pellet Surface

A 3-dimensional (3D) fuel performance analysis program, able to simulate normal operating conditions and accident conditions for PWR fuel behaviors, was developed based on the Multiphysics Object-Oriented Simulation Environment (MOOSE) finite-element framework. By taking fission products swelling, densification and expansion of pellet, thermal and irradiation creep, gap heat transfer, fission gas release, and cladding crack propagation into consideration, detailed fuel behaviors have been simulated in a multiphysics coupling way. Local defects in fuel pellet caused during manufacturing and filling processes known as the missing pellet surface (MPS) can cause abnormal stress distribution of the cladding and it could even lead to cladding failure. Taking Stress Corrosion Cracking (SCC) phenomenon into consideration, a simulation of PWR fuel rodlet that consists of a pellet with an MPS defect and an intact pellet was conducted. The fuel rod has experienced with sorts of events, including normal operating conditions and a high-power ramp event. The simulation results indicated that: 1) The MPS defect affects the temperature and displacement distribution in the vicinity of the MPS defect. When the pellets are in contact with the cladding, the inner surface of the cladding presents a large tensile hoop stress, which accelerates the crack propagation. 2) During the ramp event, the crack propagation rate was higher than that under normal condition and crack length expanded by about 0.1 µm.

Numerical analysis of the carbon containing pellets direct reduction process

In view of the carbon-containing composite pellets direct reduction process in rotary hearth furnace, a mathematical model coupling heterogeneous chemical reaction kinetics, heat and mass transfer of this process was established. The effects of furnace temperature (from 1273.15 K to 1673.15 K) and pellet radius (from 6 mm to 16 mm) on the direct reduction of carbon-containing composite pellets were studied by adopting computational fluid dynamics software. The pellet temperature and composition changes under different operating conditions were analyzed. CO and CO2 fluxes, heat fluxes on the pellet surface were especially studied. Total heat absorption by the pellet, CO and CO2 overflow from the pellet surface together with pellet degree of metallization (DOM) and zinc removal rate (ZRR) were calculated. Results show that with the increasing of furnace temperature or the decreasing of the pellet radius, the temperature difference between pellet surface and its center and the final DOM, ZRR increased. The larger the pellet radius, the smaller the heat absorption, also the smaller CO and CO2 overflow. But heat absorption and CO overflow per unit volume are higher. There is an optimal pellet radius with high CO utilization efficiency. Pellet porosity decreases at first and then increases with reducing time. It is also found that effective thermal conductivity is a major factor limiting the pellets temperature increasing. The reduction sequence of the pellets is Fe2O3→Fe3O4→FeO→Fe.

Activated aluminum for hydrogen generation from water

Al-based alloys and mechanochemically activated aluminum powders were prepared in this study, and the regularities of their hydrolysis reaction with water were studied. Aluminum alloys were prepared by melting aluminum with additions of Ga–In–Sn eutectic (5 wt.%), bismuth (3 wt.%), antimony (3 wt.%), or zinc (3 wt.%). The temperature-dependent kinetics of their hydrolysis in a temperature range 25–70 °C was studied by using a volumetric technique. The most efficient activation of the hydrolysis process was achieved for the Al–Ga– In–Sn-Zn alloy, particularly at low temperatures (5 and 25° C). The addition of bismuth to the Al–Ga–In–Sn alloy significantly decreases the hydrolysis rate, whereas the addition of antimony has only a weak effect on the process, despite the fact that the standard electrode potentials of bismuth and antimony have rather close values. Commercially available aluminum PA-4 and ASD-1 powders were mechanochemically activated by Ga–In–Sn or Ga–In–Sn–Zn eutectic alloys (5 wt.%) and graphite (1–3 wt.%) in a mixer type ball mill. Subsequently, they were pressed (P = 4 MPa) into the pellets, which were used to generate hydrogen from water via the hydrolysis process. X-ray diffraction study of the milled PA-4 powder revealed the presence of four phases, including aluminum, graphite, and two In–Sn intermetallic compounds (In3Sn and In1–xSnx, were x ≈ 0.04). The quantitative analysis by EDX showed a uniform distribution of the activating additives over the pellet surface, while the graphite was partly aggregated. Studies on the hydrolysis kinetics when utilizing Al-based pellets demonstrated that the process readily proceeds at temperatures ≥ 5° C. At the same time, the efficiency of hydrogen generation depends on the amount of the added graphite, particle size of aluminum powders, duration and medium of their mechanochemical treatment, and the hydrolysis temperature.

Na2SO4 + V2O5 Corrosion Behavior of BaNd2Ti3O10 for Thermal Barrier Coating Applications

BaNd2Ti3O10 has been considered as a promising thermal barrier coating (TBC) candidate material, which reveals many advantages over the widely used TBC material of yttria partially stabilized zirconia, such as lower thermal conductivity, better high-temperature capability, and higher resistance to environmental deposits corrosion. In this study, the hot corrosion behavior of BaNd2Ti3O10 in Na2SO4 + V2O5 molten salt at 900 °C and 1000 °C is investigated. Exposed to the salt for 4 h at 900 °C, BaNd2Ti3O10 pellets had an obvious reaction with the salt, forming corrosion products of NdVO4, TiO2, and BaSO4, and the reaction layer was ~30 μm, beneath which no salt trace could be found. Prolonging the corrosion time to 20 h, the type of the corrosion products had no change. At an elevated corrosion temperature of 1000 °C for 4 h, the corrosion products were still NdVO4, TiO2, and BaSO4, but NdVO4 revealed a significant growth, which fully covered the pellet surface. The mechanisms by which the corrosion reaction between BaNd2Ti3O10 and the molten salt occurred were discussed.

Decomposition of Ionic Liquid Solution Over CuIr-Hexaaluminate Catalysts

The objective of this study is to elucidate the catalytic performance of hexaaluminate catalysts incorporating Cu and Ir simultaneously during the decomposition of an ammonium dinitramide (ADN)-based liquid propellant. Pellet-type catalysts were prepared and their chemico-physical properties were characterized by N2 adsorption, XRD, and XRF. It was confirmed that Cu and Ir atoms are well incorporated inside the hexaaluminate matrix of the Cu(x)Ir(10-x)-hexaaluminate catalysts and the content of Ir incorporated into hexaaluminte matrix was in the range of 2.5–8.2 wt%. The Cu(7)Ir(3)-hexaaluminate catalyst showed excellent activity in decomposition of ADN-based liquid monopropellant. The activity of the Cu(7)Ir(3)-hexaaluminate catalyst was much higher than that of the Cu(7)Ir(3)/hexaaluminate-imp catalyst prepared by impregnation of Cu and Ir onto the hexaaluminate pellet surface. This is attributed to the Cu and Ir being well incorporated in the hexaaluminate matrix and the dispersion of the Cu and Ir being greater in the Cu(7)Ir(3)-hexaaluminate than in the Cu(7)Ir(3)/hexaaluminate-imp.

Ultrasound in the Detection of Floating Sialoliths

A 36-year-old man with a 3-year history of recurrent salivary colic was referred to a maxillofacial surgery department. Gray scale ultrasound (US) showed enlarged right submandibular gland, significantly dilated intraglandular duct with two sialoliths (with an artifact of acoustic shadowing) inside, one – floating (Video-Panel A and B, arrow) and another – nonmovable (arrowhead). Left nonsymptomatic normal in size gland (asterisk) is showed at Panel C. The affected gland was excised under general anesthesia due to the diagnosis of chronic submandibular obstructive sialolithiasis. Intraglandular duct contained two yellowish stones, first was an oval form with a pellet surface (Panel D, arrow), second – a round shaped with a smooth surface (Panel D, asterisk) and it was presented at US as a floating sialolith; both are easily crumbled on palpation. As the specimen and intraglandular duct were dissected longitudinally, that`s why dissected intraglandular duct (Panel D, arrowheads) is visible in both parts of the gland. Also, a 1 small calculus (Panel D, curved arrow) was found in the parenchymal ducts. Postoperative period was smooth, and 1-year follow-up after surgery, the patient has no complaints.

Development and Permeability Testing of Self-Emulsifying Atorvastatin Calcium Pellets and Tablets of Compressed Pellets

Self-emulsifying pellets (SEPs) of Atorvastatin Calcium (AtrCa) were developed and processed into tablets (SETs). Self-emulsifying drug delivery system (SEDDS) composed of oleic acid, Tween 20, Span 80 and N-Methyl-2-pyrolidone gave great solubility improvement and was used as oil in water emulsion for the preparation of SEPs. Due to the high 60% w/w SEDDS content required to achieve a therapeutic dose in the final tablet form, sonication was necessary to improve fluidity and stability. Colloidal silicon dioxide (CSD) and microcrystalline cellulose (MCC) were the solids in the pellet formulation employed at a ratio 7:3, which enabled production of pellets with high SEDDS content and acceptable friability as well. Emulsions were characterized physico-chemically, SEPs for physical properties and reconstitution, and tablets of compressed pellets for mechanical strength, disintegration into pellets and drug release. SEPs compressed with 30% MCC at 60 MPa gave tablets of adequate strength that disintegrated rapidly into pellets within 1 min. Emulsion reconstitution took longer than drug release due to adsorption of SEDDS on CSD, implying dissolution at the pellet surface in parallel to that from the dispersed droplets. Compared to the commercial tablet, drug release from the self-emulsifying forms was faster at pH 1.2 where the drug solubility is poor, but slower at pH 6.8 where the solubility is higher. Permeability and cytotoxicity were also studied using Caco-2 cells. The results showed that drug transport from the apical to basolateral compartment of the test well was 1.27 times greater for SEPs than commercial tablets, but 0.86 times lower in the opposite direction. Statistical analysis confirmed the significance of these results. Toxicity was slightly reduced. Therefore, the increased permeability in conjunction with the protection of the drug being dissolved in the SEDDS droplets, may reduce the overall effect of presystemic metabolism and enhance bioavailability.

Immobilization of Sulfur from Different Precursors on Mini Rice-Husk-Ash Pellet Coated Chitosan Film and the Application for Mercury Vapor Uptake

Stabilizing elemental mercury using elemental sulfur has been a laboratory standard method but the studies in gas system are still growing. This study aims to explore the effect of different type immobilized sulfurs toward the mercury vapor uptake in a mini gas reactor. Sulfur powder, sulfur dissolved in carbon disulfide and colloidal sulfur from sodium thiosulfate-hydrochloric acid were immobilized on mini rice-husk-ash pellets that were previously coated with chitosan film. The average thinness of chitosan film was 58 µm covered the each pellet surface with dimension of 3 mm Ø x 4 mm. The trends of the mercury uptake and the rate of absorption were described as follow; Pellet-Scolloid > Pellet-SCS2 > Pellet-Spowder. The mean percentages of mercury uptake after 1 h running at 70oC were 99.36; 89.09 and 75.00 respectively. The reverse trends were observed for the size of S-particle aggregation and the amount of S found on the pellet surface.

An experimental study on coflow diffusion combustion in a pellet-packed bed with different bed lengths

In experimental investigations on axial symmetry, over-ventilated CH 4 /air diffusion combustion in a packed bed is executed to study the height, shape and stability of the flame. The combustor is a quartz tube packed with alumina pellets in which a cylindrical fuel stream is surrounded by a coflow air nozzle. The results show that the bed length and pellet diameter have a significant influence on the flame properties. In general, the flame above the pellet surface has axial symmetry, and its shape and colour are similar to those of a conventional diffusion flame when the bed length is smaller. The colour of the flame front varies with the bed length. The changed colour indicates an increased flame front temperature and that the combustion regime above the bed surface may change from non-premixed combustion to partially premixed combustion or even premixed combustion owing to the mix and dispersion effect in the packed bed. In addition, multiple flame behaviours, such as an inclined flame front, isolated reaction zone and oscillatory motion followed by a pulsating sound with a few hertz in a packed bed, are observed experimentally. The possible reasons for these phenomena are discussed.