Increasing Exposure Time Research Articles

Unraveling the combined toxicity and removal mechanisms of fluoxetine and sertraline co-contaminants by the freshwater microalga Chlorella pyrenoidosa

Selective serotonin reuptake inhibitors (SSRIs), such as fluoxetine (FLX) and sertraline (SER), are among the most widely detected pharmaceuticals in aquatic environments, and they usually occur as mixtures. However, little is known about the combined toxicity of SSRI mixtures to microalgae and the associated removal mechanisms. This study investigated the combined toxicity of FLX and SER to the growth, photosynthetic activity, and antioxidant system of Chlorella pyrenoidosa and their removal mechanisms. The results showed that FLX and SER strongly inhibited microalgal growth with 96 h EC50 values of 493 and 61.1 μg/L, respectively. Additionally, the combined toxicity of FLX and SER towards microalgal growth exhibited an additive effect. After 4 days of short-term exposure, FLX, SER, and their mixtures caused photosynthetic damage and oxidative stress in microalgae, and the mixture's toxicity was stronger than those of individuals. However, the adverse effects on microalgal growth, photosynthetic activity, and antioxidant system were alleviated with increasing exposure time. Meanwhile, C. pyrenoidosa efficiently removed FLX (67.59%–99.08%) and SER (94.92%–99.11%) individually after 11 days of cultivation. Biodegradation (59.25%–86.21%) was the prominent removal mechanism of FLX, while both biodegradation (48.08%–88.17%) and bioaccumulation (4.74%–43.38%) contributed significantly to SER removal. The co-existence of FLX and SER lowered the removal rate and biodegradation amount of both compounds. Besides, SER inhibited C. pyrenoidosa's N-demethylation and O-dealkylation of FLX, while co-existing with FLX inhibited the excretion of the N-deamination product of SER from microalgal cells. Furthermore, the principal component analysis indicated that the removal performance of FLX, SER, and their mixtures correlated strongly to the microalgae's physiological and biochemical states. These results highlighted the significance of co-contamination during ecological risk assessments and microalgae-based bioremediation of SSRIs.

Reduction of microbial population of fresh vegetables (carrot, white radish) and dried fruits (dried fig, dried peach) using atmospheric cold plasma and its effect on physicochemical properties

Non-observance of hygiene principles during storage causes excessive growth of microorganisms in these products and the return of export products to the manufacturer. The purpose of this research is to examine the antimicrobial effects of the jet cold plasma device and its impact on the physicochemical and sensory characteristics of a carrot, white radish, dried fig, and dried peach. For this purpose, the samples were inoculated with Escherichia coli O157:H7, Enterococcus faecalis, and Aspergillus niger. Then samples were treated with atmospheric cold plasma in the form of a jet probe and DC pulse source with 17 KV and 2.26A for 0, 3, 6, 9, and 12 min. The results showed that the rate of inactivation of microorganisms increases with increasing exposure time to atmospheric cold plasma. The maximum reduction of the microbial load was observed at 17 kV and 12 min. The resistance of microorganisms in dried fig and dried peach was higher than in carrot and white radish due to lower humidity. Also, A. niger showed the highest resistance to cold plasma compared with E. coli O157:H7, and E. faecalis. By comparing the average indices of a, and b, no significant change was observed between the treated and the control samples (p > 0.05). The texture structure remained intact after plasma application, and the plasma had no destructive effect on the texture. The samples treated with cold plasma did not show a significant effect on the physicochemical and sensory characteristics of different food products. Therefore, atmospheric cold plasma technology can be used as an efficient maintenance technique to enhance the shelf life of food products.

Effect of Humidity Exposure on Microstructure and Photoluminescence Properties of Polycrystalline CsI(Tl) Screens

CsI(Tl) scintillation screens have been widely applied in X-ray nondestructive testing (NDT) because of their low cost, high scintillation efficiency, and fluorescence guide columnar microstructures. The effect of humidity exposure on the microstructure and photoluminescence properties of polycrystalline CsI(Tl) screens was investigated in this work. The results indicate that the grain diameter of the columnar microstructure increased with increased exposure time in a humid environment. The degree of anisotropy of polycrystalline screens changed from (211) and (310) to (110) orientation with exposure time. FT-IR Spectra of the exposed screens peaked at 3734 cm−1, 3710 cm−1, 3676 cm−1, 3647 cm−1, 3627 cm−1, 3598 c−1, and 3566 cm−1 due to the symmetrical and asymmetrical stretching vibrations of water molecules. In addition, the photoluminescence properties of exposed screens decreased with increased humidity exposure time due to the deliquescence caused by water molecules. After hours of humidity exposure, the photoluminescence and imaging properties of the screens decrease obviously and tend to reduce slowly. The moisture absorption and deliquescence would directly affect the service reliability and the storage lifetime of polycrystalline CsI(Tl) screens.

Single and joint toxic effects of waterborne exposure to copper and cadmium on Coregonus ussuriensis Berg.

Heavy metal contamination severely affects the aquatic environment and organisms. Copper (Cu) and cadmium (Cd) are two of the most common heavy metal contaminants that impair the survival, development, and reproduction of aquatic organisms. With the growth of agriculture and industry, there is a possibility of heavy metal pollution in Coregonus ussuriensis Berg's water source. However, there are no published studies on the toxicity to C. ussuriensis. Acute toxicity experiments in C. ussuriensis revealed the 96-h median lethal concentrations of copper and cadmium to be 0.492 mg·L-1 (95% confidence interval: 0.452-0.529) and 1.548 mg·L-1 (95% confidence interval: 1.434-1.657), respectively, and safe concentrations of 4.92 µg·L-1 and 15.48 µg·L-1, respectively. C. ussuriensis was then treated for 96 h with Cu (20% of 96 h LC50), Cd (20% of 96 h LC50), and a combination of Cu and Cd (20% of Cu 96 h LC50 + 20% of Cd 96 h LC50). The histological damage caused by the three different exposure modes to the liver and gills of C. ussuriensis was verified using hematoxylin and eosin staining. All three exposure modes caused different degrees of vacuolization, nuclear consolidation, and necrosis in the liver tissue of C. ussuriensis and edema, hyperplasia, laminar fusion, and epithelial elevation in the gill tissue compared with the reference group. The severity of the damage increased with increasing exposure time. Anti-oxidant activity in the gill and liver tissues were measured using enzyme activity assay kits to reflect oxidative stress induced by copper and cadmium exposure alone and in combination. The enzyme activities of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH) were substantially higher than those in the reference groups. However, the activities of the enzymes decreased with increasing exposure time. Malondialdehyde (MDA) activity significantly increased during exposure in relation to that in the reference group. Analysis of immune gene expression in C. ussuriensis gill and liver tissues was executed using real-time inverse transcript polymerase chain response (RT-PCR). The expression levels of the pro-inflammatory cytokines interleukin one beta (IL-1β) and tumor necrosis factor-alpha (TNF-α) were positively correlated with exposure time and were significantly upregulated with increasing exposure time. Metallothionein (MT) gene expression levels were significantly upregulated in the short term after exposure compared to the reference group but decreased with increasing exposure time. Our results indicate that exposure to aqueous copper and cadmium solutions, either alone or in combination, causes histopathological damage, oxidative stress, and immunotoxicity in C. ussuriensis gill and liver tissue. This study investigated the toxic effects of copper and cadmium on C. ussuriensis to facilitate the monitoring of heavy metals in water sources for healthy aquaculture.

Optimization of the Technology of Creating Sensitive Gas Sensors Based on Zinc Oxide

The main achievements in the development of resistive type gas sensors are analyzed, in particular, the creation of nanostructures based on metal oxides, which make it possible to significantly improve the performance characteristics of the sensors. Experimental samples of the gas sensor based on ZnO were obtained by magnetron sputtering on direct current. The effectiveness of the gas sensor system for recognition and analysis of gases and their mixtures has been established. A study of the sensitivity of experimental samples to the influence of the target gas CO was carried out. The target gas concentration varied from 50 to 150 ppm. It was established that the ZnO-based gas sensor exhibits the highest sensitivity at a target gas concentration of 100 ppm. The sensitivity of the gas sensor increases with increasing exposure time to the target gas.

Thermo-mechanical behavior of composite beams with corrugated steel webs exposed to localized fire

In this study, a one-way coupling methodology combining fire simulation based computational fluid dynamics (CFD) with finite element (FE) analysis is proposed to investigate the thermo-mechanical behaviors of composite beams with corrugated steel webs (CSWs) under localized fire exposure. Fire Dynamics Simulator (FDS) is used to simulate the local fire environment, and the adiabatic surface temperature (AST) data obtained in FDS are imported into the FE models in ABAQUS by the fds2ascii coupling tool. The validations of FDS models and the CFD-FE coupling method are verified by a localized fire test on a steel beam conducted by the National Institute of Standards and Technology (NIST). Then, the CFD-FE coupling method is applied to analyze the thermo-mechanical behaviors of composite beams with concrete flanges and CSWs exposed to localized fire. As the fire exposure time increases, the composite beam appears significant variation of the temperature gradient at elevated temperature, and induce the dynamic, uneven temperature field in the structural members. Due to the influences of the temperature gradient field, the traditional design assumptions for composite beams with CSWs are not valid when the structures suffered a localized fire. It found that the shear stress on the CSWs is no longer evenly distributed along the depth at elevated temperatures, and the concrete flange resists a considerable part of the sectional shear force, particularly of the fire-affect zone. This study hopes to provide a basis for the fire resistance design of composite girder bridges with CSWs.

Reliable p-type organic permeable base transistors—the missing component for integrated circuits

Due to their nm-range channel length, vertical organic transistors are gaining scientific interest to overcome the frequency limitations of lateral organic transistor. Especially, vertical organic permeable base transistors (OPBTs) with a structure resembling a vacuum-tube-triode stand out due to their excellent electrical performance. Recently, n-type OPBTs have been demonstrated with excellent performance and great potential to be applied in high-frequency logic circuits, display driving circuits, and light-emitting devices. However, achieving adequate p-type OPBTs to catch up with the performance of n-type devices is still challenging. Here, we report on the peculiar finding that the extended exposure of p-type OPBTs to ambient air during the fabrication has a positive effect on the electrical performance and tremendously improves the yield of devices to . Upon exposing the fresh device to air, oxygen diffuses into the semiconductor layer interacting with the base electrode, which facilitates the formation of pinholes in the base and creates an insulator layer around the base. Moreover, as oxygen acts as a p-dopants to the p-type semiconductors used in this work, the device performance is further improved, manifesting in an increased on-state current. However, as the exposure time increases, different p-type organic semiconductors show different behavior depending on their ionization potential. Comparing two semiconductor materials with a difference in their ionization potential of 0.4 eV, we show that long-term degradation could be effectively suppressed. Therefore, the positive effect of air exposure could be utilized to optimize p-type OPBTs, which offers a simple and universal way to construct high performance p-type OPBTs and possibly also complementary circuits.

Electrocatalytical effect of UV to oxidizing amoxicillin at (Sn-SnO2)-NPh-CPE: Analytical application in tap water and wastewater

The (Sn-SnO2)-NPh-CPE modified electrode at based Microparticles of tin and tin oxide scattered on natural phosphate were utilized for amoxicillin (AMX) oxidation, it was preceded by an activation phase using ultraviolet radiation (UV) as the catalytic step before its electrochemical detection. The (Sn-SnO2)-NPh modifier was prepared via a solid-state reaction process at a high temperature of 400 °C using natural phosphate and tin dichloride. The AMX activation by UV radiation was studied using differential pulse voltammetry, chronoamperometry and electrochemical impedance spectroscopy. Thus, the results confirm that the utilization of UV radiation catalyzed AMX oxidation. It has been found that the oxidation current of AMX increases with the increasing exposure time of AMX solution to UV radiation. The results demonstrated that the activation of the AMX by UV radiation before the electrochemical oxidation is necessary for its detection at the trace level. The oxidation peak current was linear to the AMX concentration in the range 2.0 × 10−7 to 2.0 × 10−6 mol/L with a detection limit of 7.78 × 10−8 mol/L. Moreover, the designed sensing platform was successfully employed to determine AMX in tap water and wastewater samples.

Grain-interior corrosion and tensile performance degradation of 2XXX Al–Li alloy in an actual marine environment

The actual marine corrosion behavior and tensile properties of 2195 alloy and 2297 alloy in T8 state were studied by means of marine environment outdoor xeposure testing. The cross-sectional and macro morphologies of the alloys after outdoor exposure for different times were analyzed. The results indicated that the alloys possessed poor marine-corrosion resistance and rapidly corroded in an actual marine environment. The grain-interior corrosion (GIC) was the main corrosion mechanism for 2195 alloy and 2297 alloy, leading a lot of corrosive holes. Moreover, the reasons for GIC was discussed through microstructure analysis. Additionally, the trend of tensile performance of both alloys during outdoor exposure to marine environment was also studied. It is found that the tensile properties of both alloys gradually degraded with the increase of exposure time due to the occurrence of corrosive holes. After exposure for 12 months, the tensile strength and yield strength of 2297 alloy declined more than these of 2195 alloy.

Tobacco smoking and blood parameters in the kurdish population of Iran

ObjectiveThis study investigates the relationship between smoking and blood parameters in the Iranian Kurdish population.MethodThe current study was conducted based on the recruitment phase of the Ravansar Non-Communicable Disease (RaNCD) cohort study.ResultsCurrent smokers had higher levels of RBC count, HCT, HGB, MCV, MCH, MCHC, WBC count, and GR%, than in other groups significantly. Passive smokers had higher levels of PLT count and PCT statistically. The increasing exposure time of smoking positively affected WBC count, GR%, PLT count, PCT, and RDW in female passive smokers. In addition, heavy smokers, as well as participants with a higher duration time of smoking, had the same results for significantly lower levels of lymphocyte and monocyte and a higher level of RBC indices.ConclusionAccording to the present study, along with the current smokers, the intensity of smoking, as well as the duration time of the smoke, could have a positive correlation with blood parameters. Furthermore, passive smokers and specifically secondhand female smokers were more vulnerable to smoke.

Inhibition of Mild Steel Corrosion by Leaves Extracts of Commelina benghalensis L In 1M HCl Solution

The inhibition of mild steel corrosion in 1M HCl by leaves extracts of Commelina benghalensis L was investigated using weight loss and potentiodynamic polarization techniques at room (30 and elevated temperatures of 40, 50, 60 and 70. The results of weight loss technique showed that the inhibition efficiency increased with increase in extract concentration and exposure time but decreased with rise in temperature. The maximum inhibition efficiency obtained was 81.71 % at 0.5 g/L concentration of leaves extracts. Corrosion rates decreased with increased concentration of extracts but increased with increase in temperature. Potentiodynamic polarization method results indicated that Commelina benghalensis L is a mixed - type inhibitor as it modified both the anodic and cathodic reactions in 1M HCl solution. The adsorption of the extracts on the mild steel coupons was observed to follow Langmuir and Temkin adsorption isotherms. The negative values of Gibb’s free energy of adsorption ranged from -21.35 to -23.03 kJ/mol., this suggests that inhibitor molecules were physically and spontaneously adsorbed onto the metal surface.

The electrical response of refractory carbon/carbon composites to high-temperature ablation: A pathway to embedded sensing in extreme environments

High-temperature ceramics and composites are essential for leading edges on next-generation high-speed aerospace vehicles, where the surfaces are expected to see extreme temperatures and heat fluxes. However, these materials are vulnerable to in-flight degradation arising from oxidation and ablation. Due to the extreme conditions encountered during flight, even slight changes in surface properties can profoundly affect aerodynamic performance and precipitate catastrophic failure. In-flight embedded sensing is therefore critical. Unfortunately, traditional sensors either prohibitively interfere with aerodynamics or cannot survive in-flight conditions. To overcome this challenge, we explore the material-as-the-sensor paradigm for extreme environment materials. Changes in the electrical properties of a refractory carbon/carbon (C/C) composite are used as an indicator of degradation. C/C composite strips were exposed to an oxyacetylene torch to represent oxidation and ablation expected during service, and the electrical impedance of the strips was measured before and after each exposure. It was found that ablation-induced damage has a clear impact on alternating current transport that scales with increasing exposure time and ablated volume. Equivalent circuit analyses were conducted in order to better understand the nature of ablation damage on transport characteristics; it was found that the resistance of the equivalent circuit increases with increasing torch exposure time and ablated volume. This study is an important proof-of-concept result for establishing embedded sensing techniques in next-generation extreme environments.

The bioceramic sealer iRoot SP promotes osteogenic differentiation of human stem cells from apical papilla via miR-141-3p/SPAG9/MAPK signalling pathway.

The premixed bioceramic sealer iRoot SP that is widely used clinically has been reported to kill bacterial biofilms and promote osteogenic differentiation of human stem cells from the apical papilla (hSCAPs). Although miR-141-3p has been substantiated to be involved in the osteogenic process, the underlying mechanisms remain unclear. The aim of this study was to investigate the role of miR-141-3p in osteogenic differentiation and underlying mechanisms of iRoot SP-treated hSCAPs. hSCAPs were extracted from tissue blocks with enzyme digestion and identified by using immunofluorescence, flow cytometry and alizarin red staining. The mRNA expression level of miR-141-3p in hSCPAs after culture with iRoot SP was examined by quantitative real-time PCR (qRT-PCR) assay. SPAG9 was identified as a downstream target gene of miR-141-3p by dual-luciferase report assay. Alkaline phosphatase (ALP) staining and activity detection, alizarin red staining, calcium concentration assay, qRT-PCR and western blot were used to estimate osteogenic differentiation ability and involved protein expression levels of the osteogenic makers and signalling pathway-related factors in iRoot SP-treated hSCAPs. Data were analysed by one-way anova and post hoc Tukey's test to determine any statistical differences between the experimental groups and the control group. p < .05 was considered statistically significant. Expression of miR-141-3p was reduced in iRoot SP-treated hSCAPs with the increased exposure time up to 7 days, and the western blot and qRT-PCR results revealed that the osteogenic markers osteocalcin (OCN), osterix (OSX), runt-related transcription factor 2 (RUNX2) and dentin sialophosphoprotein (DSPP) were inversely correlated with miR-141-3p. The negative regulatory relationship between miR-141-3p and SPAG9/ mitogen-activated protein kinases (MAPK) signalling axis was validated in this in vitro experiments. The bioceramic sealer iRoot SP promoted osteogenic differentiation of hSCAPs by inhibiting miR-141-3p following down-regulated SPAG9 expression, and activated MAPK pathway. These findings proposed a novel therapeutic impact of bioceramic sealer iRoot SP inducing bone regeneration in refractory periapical periodontitis.

Analysis on Protection Coordination of OCRs Using Index for Impedance Compensation Considering Unsymmetrical Ground Fault in a Power Distribution System With SFCL

The superconducting fault current limiter (SFCL) has been spotlighted as the effective device to limit the fault current because it has no effect on a power distribution system in a normal time due to its zero resistance. However, the SFCL causes the trip of the overcurrent relays (OCRs) to be delayed due to the reduc-tion of the fault current, which causes a negative impact on the protection coordination of power distribution system. The delayed trip of OCR makes the exposure time's increase of the neighboring power facilities from the fault current at fault line. In this paper, the OCR's index for the impedance compensation of the SFCL in case of the unsymmetrical ground fault was suggested. The sug-gested OCR's index consists of all sequence components for the impedance, calculated from the voltages and the currents meas-ured from both the power distribution system and the SFCL. To prove the effectiveness of algorithm, the protection coordination between OCRs in a power distribution system with the SFCL were analyzed for the unsymmetrical ground fault as well as the sym-metrical ground fault through the simulation using PSCAD/ EMTDC.

The effect of heat input in multi-pass GMAW of S960QL UHSS based on weaving and stringer bead procedure on microstructure and mechanical properties of HAZ

Quenched and tempered S960QL (yield strength ≥ 960 MPa) ultra-high strength steel (UHSS) thick plates were joined by multi-pass robotic gas metal arc welding (GMAW) using weaving and stringer bead techniques. The effects of microstructural changes in heat-affected zone (HAZ) of the joint on toughness and hardness were examined. Weaving and stringer bead techniques applied for the multi-pass welding procedure altered average peak temperatures and exposure time to those temperatures. Mechanical properties of HAZs were evaluated by utilizing notch impact and hardness tests, and these results were correlated with microstructural characterizations using optical (OM) and scanning electron microscopes (SEM). Prior austenite grain (PAG) coarsening occurred because of increased exposure time to peak temperature in coarse-grained HAZ (CGHAZ) of the W-5 (weaving pass) joint. CGHAZs at the face pass, which have not been subjected to a second thermal cycle, have the highest hardness in both joints. Hardness of SCHAZ and CGHAZ of S-12 joint was 7% and 1% higher compared with W-5 joint, respectively. Weld metal hardness of W-5 joint was 15% lower than that of S-12 joint. Both joints not only fulfilled the requirements of minimum 50 J per EN ISO 10025-6 at −20 °C but exceeded this limit by 50% (W-5) and 200% (S-12). Lateral expansions for impact toughness specimens were around 17.5% for S-12 joint, whereas it was 4% for W-5 joint. Since HAZ in the S-12 (stringer bead) joint is narrow compared with the one in the W-5 joint, impact toughness values were higher with the S-12 joint due to the locations of the notches of the impact specimens.

Studying Luminal, A and B subtypes of the breast cancer under paracrine secretion of fibroblasts

Introduction Understanding the role of the tumor microenvironment in specifying molecule markers of breast cancer subtypes could involve tumor microenvironment properties in subtyping and clinical assessment of breast cancer. Therefore, interconversion of luminal states and or their specific markers alteration under the control of TME particularly CAFs deserve to be more investigated. Methods To activate normal human fibroblasts, liquid overlay technique or nemesis was used and α-SMA expression, CAFs marker, in fibroblastic spheroids was measured by blotting. The luminal A, MCF-7, and luminal B, MDA-MB 361, cell lines are treated with normal and spheroidal/activated fibroblast conditioned medium for 48 hours. The morphological changes of luminal A and B cells were evaluated by invert microscopy and analyzed by the shape factor formula. Moreover, sensitivity changes to chemotherapeutic agents, Ki67 expression, and gene expression level including ER-related and proliferative genes were assessed respectively by MTT assay, Immunofluorescence, and real time qRT-PCR methods. Results Activated fibroblast, spheroid form, by LOT/nemosis expressed α-SMA marker two folds more than monolayer cultured fibroblasts. Our study underlined a significant increase in IC50 of both luminal A and B cell lines after being co-cultured with conditioned medium markedly in spheroidal conditioned medium. Morphological changes study by shape factor formula demonstrated more aggressiveness with gaining mesenchymal features both in luminal A and B subtypes by increasing exposure time. Changes in Ki67 expression level were observed after fibroblasts and spheroidal paracrine conditioning. Only this data supports the luminal interconversion by elevated Ki67 expression in luminal A and lowered Ki67 expression in luminal B. Gene expression results revealed that the MCF7 and MDA-MB cells as representatives luminal A and B subtypes in this study did not interchange their own specific gene pattern, however both luminal types in co-culture with condition medium increased the expression of anti-apoptotic Bcl2 gene. Conclusion Under the paracrine influence of fibroblast cells, both luminal A(MCF7) and B (MDA-MB) subtypes of breast cancer gained invasive, anti-apoptotic, and chemoresistance features which are mostly increased by activated fibroblast conditioned medium mimicking CAFs. There was no strong proof for interconversion of luminal A and B, with more similarities, subtypes of breast cancer.

Studies on Effects of Chronic Exposure of Some Organophosphates to Catla catla (HaM.)

The present study deals with the long-term toxic effects of the lowest sub-lethal concentration of dimethoate and malathion on a freshwater fish Catla catla. Toxicity is measured in terms of inhibition in acetylcholinesterase activity and fish behaviour. Technical grades of dimethoate (30 EC) and malathion (50 EC) were used for the present study. LC50 values for 96 hours were calculated for both pesticides. The lowest sublethal concentration (1/5 of LC50) of both pesticides was taken for chronic exposure. As organophosphates are potent inhibitors of acetylcholinesterase (AChE) activity, the AChE activity was estimated by the method of Metcalf (1957) in the brain and liver tissue of the test fishes to evaluate chronic toxicity. The fish were observed regularly to analyse the changes in behaviour. A significant increase in inhibition of acetylcholinesterase activity was observed. Experimental fishes exhibited a decreased rate of opercular movement, loss of balance, excessive mucous secretion, erratic swimming, and increased surfacing with increasing exposure time. Probable reasons for these alterations have been discussed in detail.

Effect of time-dependent layer formation on the oxygen transport capacity of ilmenite during combustion of ash-rich woody biomass

Oxygen carrier aided combustion (OCAC) is a novel technology that aims to enhance combustion of heterogenous fuels by replacing the inert bed material with an active oxygen carrier. One of the promising oxygen carriers is natural ilmenite which shows decent oxygen transport capacity and mechanical stability under OCAC operating conditions. However, interactions between ilmenite and woody biomass ash lead to the formation of a calcium-rich ash layer, which affects the ability of the oxygen carrier (OC) to transfer oxygen throughout the boiler and subsequently decreases the combustion efficiency. This paper focuses on the time-dependent morphological and compositional changes in ilmenite bed particles and the consequence effects on the oxygen transport capacity and reactivity of ilmenite. Ilmenite utilized in this study was investigated in a 5 kW bubbling fluidized bed combustion unit, utilizing ash-rich bark pellets as fuel. A negative effect of iron migration on the oxygen transport capacity was observed in ilmenite bed particles after 6 h of operation in the bubbling fluidized bed reactor. The decrease in the oxygen transport capacity of ilmenite was found to correlate with the increased exposure time in the fluidized bed reactor and was caused by the migration and subsequent erosion of Fe from the ilmenite particles. On the other hand, the older bed particles show an increase in reaction rate, presumably due to the catalytic activity of the calcium-enriched outer layer on the bed particle surface.

Controlled Degradation of Polycaprolactone Polymers through Ultrasound Stimulation.

This study describes the development of an ultrasound-responsive polymer system that provides on-demand degradation when exposed to high-intensity focused ultrasound (HIFU). Diels-Alder cycloadducts were used to crosslink polycaprolactone (PCL) polymers and underwent a retro Diels-Alder reaction when stimulated with HIFU. Two Diels-Alder polymer compositions were explored to evaluate the link between reverse reaction energy barriers and polymer degradation rates. PCL crosslinked with isosorbide was also used as a non-Diels-Alder-based control polymer. An increase of HIFU exposure time and amplitude correlated with an increase of PCL degradation for Diels-Alder-based polymers. Ultrasound imaging during HIFU allowed for real-time visualization of the on-demand degradation through cavitation-based mechanisms. The temperature surrounding the sample was monitored with a thermocouple during HIFU stimulation; a minimal increase in temperature was observed. PCL polymers were characterized using Fourier transform infrared (FTIR) spectroscopy, nuclear magnetic resonance (NMR), differential scanning calorimetry (DSC), optical profilometry, and mechanical testing. PCL degradation byproducts were identified by mass spectrometry, and their cytocompatibility was evaluated in vitro. Overall, this study demonstrated that HIFU is an effective image-guided, external stimulus to control the degradation of Diels-Alder-based PCL polymers on-demand.

3D printed mucoadhesive orodispersible films manufactured by direct powder extrusion for personalized clobetasol propionate based paediatric therapies

The aim of this work is the development and production by Direct Powder Extrusion (DPE) 3D printing technique of novel oral mucoadhesive films delivering Clobetasol propionate (CBS), useful in paediatric treatment of Oral Lichen Planus (OLP), a rare chronic disease. The DPE 3D printing of these dosage forms can allow the reduction of frequency regimen, the therapy personalization, and reduction of oral cavity administration discomfort. To obtain suitable mucoadhesive films, different polymeric materials, namely hydroxypropylmethylcellulose or polyethylene oxide blended with chitosan (CS), were tested and hydroxypropyl-β-cyclodextrin was added to increase the CBS solubility. The formulations were tested in terms of mechanical, physico-chemical, and in vitro biopharmaceutical properties. The film showed a tenacious structure, with drug chemical-physical characteristics enhancement due to its partial amorphization during the printing stage and owing to cyclodextrins multicomponent complex formation. The presence of CS enhanced the mucoadhesive properties leading to a significant increase of drug exposure time on the mucosa. Finally, the printed films permeation and retention studies through porcine mucosae showed a marked retention of the drug inside the epithelium, avoiding drug systemic absorption. Therefore, DPE-printed films could represent a suitable technique for the preparation of mucoadhesive film potentially usable for paediatric therapy including OLP.