Uniform Size Research Articles

Photodynamic effect of vascular-targeted polyphenol nanoparticles on Endothelial cells

BackgroundPort wine stains (PWS) are vascular malformations, and photodynamic therapy (PDT) is a promising treatment. Emerging drug delivery methods employ nanoparticles (NPs) to enhance drug permeability and retention in diseased blood vessels and improve drug bioavailability. (-) -epigallocatechin-3-gallate glycine (EGCG) has anti-angiogenetic effects and boosts photodynamic therapy. Chlorin e6 (Ce6) is capable of efficiently producing singlet oxygen, rendering it a very promising photosensitizer for utilization in nanomedicine. Material and MethodsEGCG-Ce6-NPs were synthesized and characterized using various techniques. The photodynamic effects of EGCG-Ce6-NPs on endothelial cells were evaluated. The compatibility and toxicity of the nanoparticle was tested using the CCK-8 assay. The intracellular uptake of the nanoparticle was observed using an inverted fluorescence microscope, and the intracellular fluorescence intensity was detected using flow cytometry. The ROS generation and apoptosis induced by EGCG-Ce6-NPs was observed using confocal laser scanning microscopy and flow cytometry respectively. ResultsEGCG-Ce6-NPs exhibited stability, spherical shape of uniform size while reducing the particle diameter, low polydisperse profile and retaining the ability to effectively generate singlet oxygen. These characteristics suggest promising potential for enhancing drug permeability and retention. Additionally, EGCG-Ce6-NPs demonstrated good compatibility with endothelial cells and enhanced intracellular uptake of Ce6. Furthermore, EGCG-Ce6-NPs increased activation efficiency, induced significant toxicity, more reactive oxygen species, and a higher rate of late apoptosis after laser irradiation. ConclusionThis in vitro study showed the potentials EGCG-Ce6-NPs for the destruction of endothelial cells in vasculature.

Remediation of pharmacophoric laboratory waste by using biodegradable carbon nanoparticles of bacterial biofilm origin

Research laboratories generate a broad range of hazardous pharmacophoric chemical contaminants, from drugs to dyes used during various experimental procedures. In the recent past, biological methods have demonstrated great potential in the remediation of such contaminants. However, the presence of pharmacophoric chemicals containing antibiotics, xenobiotics, and heavy metals suppresses the growth and survivability of used microbial agents, thus decreasing the overall efficiency of biological remediation processes. Bacterial biofilm is a natural arrangement to counter some of these inhibitions but its use in a systemic manner, portable devices, and pollutant remediation plants post serious challenges. This could be countered by synthesizing a biodegradable carbon nanoparticle from bacterial biofilm. In this study, extracellular polymeric substance-based carbon nanoparticles (Bio-EPS-CNPs) were synthesized from bacterial biofilm derived from Bacillus subtilis NCIB 3610, as a model bacterial system. The produced Bio-EPS-CNPs were investigated for physiochemical properties by dynamic light scattering, optical, Fourier-transformed infrared, and Raman spectroscopy techniques, whereas X-ray diffraction study, scanning electron microscopy, and transmission electron microscopy were used to investigate structural and morphological features. The Bio-EPS-CNPs exhibited negative surface charge with spherical morphology having a uniform size of sub-100 nm. The maximum remediation of some laboratory-produced pharmacophoric chemicals was achieved through a five-round scavenging process and confirmed by UV/Vis spectroscopic analysis with respect to the used pharmacophore. This bioinspired remediation of used pharmacophoric chemicals was achieved through the mechanism of surface adsorption via hydrogen bonding and electrostatic interactions, as revealed by different characterizations. Further experiments were performed to investigate the effects of pH, temperature, stirring, and the protocol of scavenging to establish Bio-EPS-CNP as a possible alternative to be used in research laboratories for efficient removal of pharmacophoric chemicals by incorporating it in a portable, filter-based device.

Fluorocarbon Nanodroplets: Their Formation and Stability in Complex Solution Systems.

Perfluorocarbon (PFC) nanodroplets (NDs) are expanding in a wide range of applications in biotechnology and nanotechnology. Their efficacy in biological systems is significantly influenced by their size uniformity and stability within bioelectrolyte contexts. Presently, methods for creating monodisperse, highly concentrated, and well-stabilized PFC NDs under harsh conditions using low energy consumption methods have not been thoroughly developed, and their stability has not been sufficiently explored. This gap restricts their applicability for advanced medical interventions in tissues with high pH levels and various electrolytic conditions. To tackle these challenges and to circumvent potential toxicity from surface stabilizers, we have conducted an in-depth investigation into the formation and stability of uncoated perfluorohexane (PFH) NDs, which were synthesized by using a low-energy consumption solvent exchange technique, across complex electrolyte compositions or a broad spectrum of pH levels. The results indicated that low concentrations of low-valent electrolyte ions facilitate the nucleation of NDs and consistently accelerate Ostwald ripening over an extended period. Conversely, high concentrations of highly valent electrolyte ions inhibit nucleation and decelerate the ripening process over time. Given the similarities between the properties of NDs and nanobubbles, we propose a potential stabilization mechanism. Electrolytes influence the Ostwald ripening of NDs by adjusting the adsorption and distribution of ions on the NDs' surface, modifying the thickness of the electric double layer, and fine-tuning the energy barrier between droplets. These insights enable precise control over the stability of PFC NDs through the meticulous adjustment of the surrounding electrolyte composition. This offers an effective preparation method and a theoretical foundation for employing bare PFC NDs in physiological settings.

Droplet Formation and Energy Input during Induction Wire Melting with Pulsed and Constant Generator Power

Induction heating is a fast, reproducible, and efficient heating method used in various manufacturing processes. However, there is no established additive manufacturing (AM) process based on induction heating using wire as feedstock. This study investigates a novel approach to AM based on inductive heating, where a steel wire is melted and droplets are detached periodically using a two-winding induction coil. The process parameters and energy input into the droplets are characterized. The induction generator exhibits a sluggish response to the excitation voltage, resulting in a lag in the coil current. The process is captured using a high-speed camera, revealing a regular droplet formation of 14 Hz and uniform shapes and sizes between 2.11 and 2.65 mm in diameter when operated within an appropriate process window. Larger drops and increased spatter formation occur outside this window. The proposed method allows for the production of droplets with almost spherical shapes. Further analysis and characterization of droplet formation and energy input provide insights into process optimization and indicate an overall efficiency of approximately 10%.

Production and characterization of a blood analogue based on alginate microparticles

This work addresses the need for a universal blood substitute by focusing on developing alginate-based microparticles engineered to replicate the mechanical properties of red blood cells (RBCs). Alginate, known for its biocompatibility and tunable mechanical properties, is used to create microparticles that closely resemble RBCs in size and shape. These alginate microparticles are produced through premix membrane emulsification (PME), ensuring a uniform size distribution. The viscosity ratio and the size of the filter pores influence the final size of the microparticles. Filters with pores of 20 µm were used to produce 5 wt% alginate microparticles with a diameter of 7.81 µm ± 0.77, and filters with pores of 30 µm were used to produce 0.5 wt% alginate microparticles with a diameter of 8.69 µm ± 3.30. The Deformability Index (DI) of the alginate microparticles follows the correlation that microparticles with higher elastic modulus exhibit lower DI values. The DI found for 0.5 wt% alginate microparticles solution is higher than the DI found for 5 wt% alginate microparticles. The DI of RBCs is higher than the ones found for the alginate microparticles, however the value is in the range of the experimental error. Rheological studies reveal that suspensions of 25–30 wt% alginate microparticles exhibit a shear-thinning behavior similar to human blood. The DI of the alginate microparticles shows little influence on the rheology of the suspensions. Furthermore, the Cell-Free Layer (CFL) of alginate microparticles is close to that of RBCs, reinforcing the potential of alginate as a suitable material for blood substitute development. The alginate microparticles produced in this work show a great potential to contribute to creating a blood-mimicking fluid for applications in medical treatments and research.

Facile fabrication of pesticide nanocapsules using cinnamaldehyde derived imide polymer as wall material for pH-responsive and ultraviolet shielding properties

The low utilization efficiency of pesticides poses a significant challenge to the sustainable development of agriculture. The nanocapsule-based pesticide delivery systems combine the advantages of nanotechnology and advanced materials to achieve on-demand and accurately targeted release. Herein, a facile and universal strategy was used to fabricate photosensitive pesticide nanocapsules using a versatile imine polymer derived from cinnamaldehyde (CIN) and ε-poly-L-lysine (PLL). Characterization results demonstrated that the nanocapsules prepared under optimal conditions exhibited uniform sizes (200–400 nm) and high encapsulation efficiency (>90 %). Photodegradation experiments revealed a significant increase of half-lives (7.21–55.57 times) under UV irradiation for the different pesticide nanocapsules. Furthermore, the pesticide nanocapsules demonstrated a high biological activity and excellent physicochemical properties, including pH-responsive release, maximum retention, and rain erosion resistance. The results of the mechanistic studies on the increased biological activity indicated that the nanocapsules could be adsorbed on the surface of target pathogenic cells and then released CIN and PLL, destroying the integrity of the cell membrane, and synergistically and effectively eradicating the pathogen with pesticide. Additionally, nanocapsules exhibited lower toxicity to zebrafish and genetic toxicity to Vicia faba than pesticide technical. Therefore, stimuli-responsive nanocapsules based on imide polymer have broad application prospects in the field of pesticides.

Synthesis of Ag and AgCl Nanoparticles Using Klasea latifolia and Klassa leptoclada Extracts and Assessment of the Antimicrobial Properties of the Synthesized Nanoparticles and Antioxidant Properties of the Extracts

Background: In green synthesis, metal ions are transformed into nanoparticles through a simple reaction, without the need for surfactants, specific conditions, and other stabilizing agents. Methods: This study performed the biosynthesis of silver nanoparticles using the extract of Klasea latifolia and Klasea leptoclada. objective: In green synthesis, metal ions are transformed into nanoparticles through a simple reaction, without the need for surfactants, specific conditions (e.g., temperature and pressure), and other stabilizing agents. Herbs, including flavonoids and other water-soluble active metabolites, could also be used to reduce metal ions to nanoparticles at room temperature. Therefore, the objective of the current research was to investigate the green synthesis of silver nanoparticles using Klasea leptoclada and Klasea latifolia extracts. Results: Nanoparticles were characterized using the SEM, XRD, UV-Visible Spectroscopy, and EDS methods. The antibacterial properties of the extracts and synthesized nanoparticles were evaluated against Staphylococcus aureus, Bacillus cereus, and Escherichia coli using the agar disk-diffusion and well-diffusion. The antioxidants of the herbs were investigated using the DPPH and FRAP methods, and the IC50 of the extracts was determined as well. The results showed that, although no chlorinated compounds were added to the reaction medium, in addition to silver nanoparticles, silver chloride nanoparticles were also synthesized. The synthesized nanoparticles were spherical (size: 27-38 nm) and had uniform size distribution. Furthermore, the synthesized nanoparticles and extracts exhibited significant antibacterial activity. Conclusion: Many plants have been used for the biosynthesis of silver nanoparticles, but the advantage of using the extract of K.latifolia and K. leptoclada was that in addition to synthesizing silver nanoparticles, silver chloride nanoparticles were also synthesized.

Microfluidics-assisted fabrication of natural killer cell-laden microgel enhances the therapeutic efficacy for tumor immunotherapy

Recently, interest in cancer immunotherapy has increased over traditional anti-cancer therapies such as chemotherapy or targeted therapy. Natural killer (NK) cells are part of the immune cell family and essential to tumor immunotherapy as they detect and kill cancer cells. However, the disadvantage of NK cells is that cell culture is difficult. In this study, porous microgels have been fabricated using microfluidic channels to effectively culture NK cells. Microgel fabrication using microfluidics can be mass-produced in a short time and can be made in a uniform size. Microgels consist of photo cross-linkable polymers such as methacrylic gelatin (GelMa) and can be regulated via controlled GelMa concentrations. NK92 cell-laden three-dimensional (3D) microgels increase mRNA expression levels, NK92 cell proliferation, cytokine release, and anti-tumor efficacy, compared with two-dimensional (2D) cultures. In addition, the study confirms that 3D-cultured NK92 cells enhance anti-tumor effects compared with enhancement by 2D-cultured NK92 cells in the K562 leukemia mouse model. Microgels containing healthy NK cells are designed to completely degrade after 5 days allowing NK cells to be released to achieve cell-to-cell interaction with cancer cells. Overall, this microgel system provides a new cell culture platform for the effective culturing of NK cells and a new strategy for developing immune cell therapy.

Gel-casting of mesoporous silica electrolyte membranes loaded with phosphoric acid for protonic electrolyte cells

Proton conducting membranes that operate at temperatures above 100 °C are highly sought after for use in energy devices such as fuel cells owing to the high catalytic activity of electrodes induced by elevated temperature and no requirement for water management. In the present study, novel mesoporous silica membranes were prepared by a gel-casting process using commercial colloidal silica and subsequent sintering. These membranes served as the scaffold for phosphoric acid-based electrolytes. Well-interconnected mesopores with uniform pore sizes was effective for hosting phosphoric acid (PA), and the tunable pore sizes (5.9–32.0 nm) were achieved by tuning the sintering temperature from 500 to 725 °C. High porosity (about 50%) and high hydrophilicity of silica membranes are beneficial to reach high phosphoric acid loading by an impregnation process. The PA-loaded membrane sintered at 700 °C achieved a high protonic conductivity of 0.11 S cm−1 and a peak power density of 287.3 mW cm−2 in hydrogen fuel cells at 160 °C. The conductivity is 1 order of magnitude higher than that of the pressed meso-silica membranes and comparable to that of PA-mesoporous silica spheres. This study has demonstrated a new method to construct high-temperature protonic electrolyte membranes.

A carrier-free injectable hydrogel self-assembled using natural thymol and glycyrrhizin for MRSA-infected wound healing in rats

A carrier-free, self-assembled, injectable hydrogel was developed as wound dressing to deal with skin wound bleeding, bacterial infections, and wound healing. Natural thymol (THY) and glycyrrhizin were used to construct THY-loaded glycymicelles (THY@glycymicelles), which greatly improved the aqueous solubility of THY. Optimal THY@glycymicelles had a high encapsulation efficiency of THY and a uniform nanoparticle size. Interestingly, THY@glycymicelles could reversibly transform into THY@glycyrrhizin hydrogel (THY@glycygel) by adjusting neutral pH to skin pH (pH ∼ 4.9), and vice versa. THY@glycygel had a dense porous sponge microstructure and showed many excellent features, including injectable, hemostatic, antibacterial, and anti-inflammatory properties. In vitro antibacterial evaluation, THY@glycygel showed lower minimum inhibitory concentration to three tested bacteria than free THY. In terms of antibacterial mechanism, THY@glycygel could destroy the bacterial cell wall and membrane, increasing the extracellular alkaline phosphatase release, and inhibiting biofilm. THY@glycygel had strong hemostatic ability and exhibited great potential for antimicrobial activity and improving wound healing infected by methicillin-resistant Staphylococcus aureus (MRSA). Mechanisms including antimicrobial, promoting hair follicle growth, improving epidermis remolding and collagen deposition, decreasing inflammatory cytokine levels, and increasing growth factor levels promoted the MRSA-infected skin wound healing process of THY@glycygel. Totally, this novel hydrogel has great potential as wound dressing.

Intrinsically microporous polyimide membranes with synergistic aromatic and alicyclic linking groups for efficient molecular separation

Polymers of intrinsic microporosity (PIMs) are widely recognized for having great potential in reforming membrane technology for molecular separation within organic solvents, due to their rich and appropriate pore structures with a size < 2 nm. However, the swelling in organic solvents has a significant effect on their pore structures due to the amorphous and linear nature, resulting in the permeability and selectivity performances of developed PIM membranes being far from ideal. In this work, we synthesized an advanced polyimide of intrinsic microporosity by integrating a Tröger’s base (TB) structure with an synergistic structure of aromatic (naphthalenediimide, NDI) and alicyclic (bicyclooctenediimide, BCODI) linking groups. The TB with a rigid and twisted structure was used to furnish a basis for inhibiting chain packing for high overall free volume. The ultra-rigid NDI units maintained such a tailored high free volume and provided superior solvent resistance. The relatively flexible and polar BCODI units promoted local chain mobility to tailor uniform pore size distribution and increased affinity for polar solvents. The innovative design fostered the formation of stable, uniform, and highly solvent-accessible intrinsic micropores. The prepared TFC membrane exhibited good organic solvent separation capabilities, achieving an ethanol permeance of 7.6 L m-2 h−1 bar−1 and a low molecular weight cut-off (MWCO) of approximately 470 Da. This work contributes significantly to the strategic design of PIMs for preparing high-performance membranes for realistic chemical-related separation application scenarios.

Green Synthesis of Selenium Nanoparticles: Characterization and Therapeutic Applications in Microbial and Cancer Treatments

Selenium is one of these micronutrients that are essential for animals, plants and microorganisms to remain functional. This review is about the green synthesis of selenium nanoparticles and its application in microbial and cancer therapies. Our hypothesis was that Se NPs produced using plant extracts might offer the biocompatibility and environmental friendliness advantages, and hence be a new prospect for medical applications. To test our hypothesis, we conducted a comprehensive analysis of recent literature, exploring various green synthesis conditions and processes for Se NPs. Various characterisation techniques such as spectroscopy, microscopy and physicochemistry were discussed in order to provide insight into the formation and function of green-synthesised Se NPs. Our findings show that Se NPs produced by green chemistry methods have good properties such as uniform size, shape and stability as detailed examples from recent studies reveal. Furthermore, we discussed the therapeutic and theranostic applications of Se NPs produced in this manner: their potential in antimicrobial and anticancer treatments. Through illustrations of cases where Se NPs inhibit microbial growth and cause apoptosis in cancer cells, the practical significance of our findings was underscored. In summary, our review affirms that using green-mediated synthesis Se NPs improves their biocompatibility and therapeutic efficacy, thus opening up new realms for their application in medical research.

Highly Uniform Nanodiamond-Graphene Composites Microspheres for Electrocatalytic Hydrogen Evolution.

To progress the clean hydrogen-gas-based energy economy, there is a demand for cost-effective, highly efficient catalysts to facilitate the hydrogen evolution reaction process (HER). Due to the amazing catalytic capabilities of two-dimensional materials, extensive research has been done on these structures. However, most of the described syntheses take a lot of time, are challenging, and are ineffective. The present work demonstrates the performance of the recently reported nanodiamond/graphene composite microsphere ND-GCSs as a catalyst for HER. These spheres were produced via the microwave-irradiation approach. A modified process was adopted to improve the particle size uniformity and yield. The prepared composite spheres showed very interesting catalytic activity for the HER when assembled on a screen-printed carbon electrode. The prepared ND-GCSs@SPCE showed a significant shift of the onset potential to ca. -450 mV and a small Tafel slope value of ca. 85 mV/decade. The electron transfer was drastically enhanced with a tremendous decrease in charge transfer resistance to ca. 265 Ω. The electrocatalyst showed excellent long-term stability for the HER application. Additionally, this novel composite structure might be beneficial for diverse applications including batteries, supercapacitors, catalyst supports, and more.

Macrophage membrane-camouflaged pH-sensitive nanoparticles for targeted therapy of oral squamous cell carcinoma

BackgroundOral cancer is the most common malignant tumor of the head and neck, and 90% of cases are oral squamous cell carcinoma (OSCC). Chemotherapy is an important component of comprehensive treatment for OSCC. However, the clinical treatment effect of chemotherapy drugs, such as doxorubicin (DOX), is limited due to the lack of tumor targeting and rapid clearance by the immune system. Thus, based on the tumor-targeting and immune evasion abilities of macrophages, macrophage membrane-encapsulated poly(methyl vinyl ether alt maleic anhydride)-phenylboronic acid-doxorubicin nanoparticles (MM@PMVEMA-PBA-DOX NPs), briefly as MM@DOX NPs, were designed to target OSCC. The boronate ester bonds between PBA and DOX responded to the low pH value in the tumor microenvironment, selectively releasing the loaded DOX.ResultsThe results showed that MM@DOX NPs exhibited uniform particle size and typical core-shell structure. As the pH decreased from 7.4 to 5.5, drug release increased from 14 to 21%. The in vitro targeting ability, immune evasion ability, and cytotoxicity of MM@DOX NPs were verified in HN6 and SCC15 cell lines. Compared to free DOX, flow cytometry and fluorescence images demonstrated higher uptake of MM@DOX NPs by tumor cells and lower uptake by macrophages. Cell toxicity and live/dead staining experiments showed that MM@DOX NPs exhibited stronger in vitro antitumor effects than free DOX. The targeting and therapeutic effects were further confirmed in vivo. Based on in vivo biodistribution of the nanoparticles, the accumulation of MM@DOX NPs at the tumor site was increased. The pharmacokinetic results demonstrated a longer half-life of 9.26 h for MM@DOX NPs compared to 1.94 h for free DOX. Moreover, MM@DOX NPs exhibited stronger tumor suppression effects in HN6 tumor-bearing mice and good biocompatibility.ConclusionsTherefore, MM@DOX NPs is a safe and efficient therapeutic platform for OSCC.

Quality Characteristics of Vegan Mayonnaise Produced Using Supercritical Carbon Dioxide-Processed Defatted Soybean Flour.

Emulsifiers, like egg yolk (EY), are necessary for the formation of mayonnaise, which is an oil-in-water type of colloid. This study aimed to assess the potential of defatted soybean powder treated with supercritical carbon dioxide (DSF) to enhance the quality of plant-based mayonnaise as plant-based alternatives gain popularity. This study involved the production of DSF and the comparison of its quality attributes to those of mayonnaise made with varying amounts of control soy flour (CSF), DSF, and EY. It was found that mayonnaise made with an increased quantity of DSF showed better emulsion stability, viscosity, and a smaller, more uniform particle size when compared with CSF mayonnaise. Additionally, DSF mayonnaise was generally rated higher in sensory evaluation. The addition of approximately 2% DSF positively influenced the emulsion and sensory properties of the vegan mayonnaise, indicating that DSF is a promising plant-based alternative emulsifier for the replacement of animal ingredients.

Monodispersed Renewable Particles by Cascade and Density Gradient Size Fractionation to Advance Lignin Nanotechnologies.

Control over particle size and shape heterogeneity is highly relevant to the design of photonic coatings and supracolloidal assemblies. Most developments in the area have relied on mineral and petroleum-derived polymers that achieve well-defined chemical and dimensional characteristics. Unfortunately, it is challenging to attain such control when considering renewable nanoparticles. Herein, a pathway toward selectable biobased particle size and physicochemical profiles is proposed. Specifically, lignin is fractionated, a widely available heterogeneous polymer that can be dissolved in aqueous solution, to obtain a variety of monodispersed particle fractions. A two-stage cascade and density gradient centrifugation that relieves the need for solvent pre-extraction or other pretreatments but achieves particle bins of uniform size (~60 to 860nm and polydispersity, PDI<0.06, dynamic light scattering) along with characteristic surface chemical features is introduced. It is found that the properties and associated colloidal behavior of the particles are suitably classified in distinctive size populations, namely, i) nanoscale (50-100nm), ii) photonic (100-300nm) and iii) near-micron (300-1000nm). The strong correlation that exists between size and physicochemical characteristics (molar mass, surface charge, bonding and functional groups, among others) is introduced as a powerful pathway to identify nanotechnological uses that benefit from the functionality and cost-effectiveness of biogenic particles.

Improvement effect of Co and Ce oxides on the properties of CeO2-Co2O3-Fe2O3 anode materials

Lithium-ion batteries offer several advantages, including high specific energy, extended lifespan, portability, and environmental friendliness. Transition metal oxides are attractive candidates for negative electrode materials due to their higher theoretical specific capacity. To address issues related to poor stability and volume expansion, cobalt trioxide and cerium oxide were introduced as dopants in iron oxide. This study involved the preparation of Co2O3-Fe2O3 and CeO2-Co2O3-Fe2O3 composites, followed by structural characterization and investigation of their electrochemical properties. The doping of cobalt and cerium oxide proved advantageous in refining particle size. Notably, 1% Co2O3-Fe2O3 particles displayed uniform sizing and tight binding. Additionally, the sample containing 0.05% CeO2 exhibited the smallest particle size and a more homogeneous distribution. Furthermore, cobalt and cerium oxide doping significantly improved electrochemical stability. The discharge capacity of 1% Co2O3-Fe2O3 and 0.05% CeO2-1% Co2O3-Fe2O3 after undergoing 100 constant-current charge and discharge cycle respectively remained at 553.17 mAh/g, 698.57 mAh/g. As a negative electrode material in lithium-ion batteries, the composite oxide 0.05% CeO2-1% Co2O3-Fe2O3 demonstrated superior reversibility and stability during the process of lithium-ion insertion and removal, while also exhibiting low contact resistance and charge transfer resistance.

The Influence of Mo Content and Annealing on the Oxidation Behavior of Arc‐Melted Cr–xMo–8Si Alloys

The influence of Mo (10–40 at%) additions to Cr–8 at%Si is systematically studied by analyzing arc‐melted alloys in the as‐cast and annealed state. The oxidation resistance is tested by thermogravimetric analysis (TGA) at 1200 °C in air for up to 100 h. Samples are characterized by X‐ray diffraction, scanning electron microscopy, and wavelength‐dispersive X‐ray spectroscopy. The studied Cr–xMo–8Si alloy series shows a beneficial effect of Mo on the corrosion behavior. For all of the investigated Mo contents, no nitridation is observed and the oxide scale adhesion is improved. An increased amount of intermetallic A15 phase leads to the formation of a SiO2 scale beneath the Cr2O3 layer during high‐temperature exposure. The internal SiO2 layer inhibits further internal oxidation of the A15 phase. Uniform size and distribution of A15, benefits the formation of a duplex oxide scale. Cr–25Mo–8 at%Si, shows the most promising oxidation behavior. The TGA data follows the paralinear law, with both the growth rate, kp, and volatilization rate, kv, of Cr2O3 being reduced by adding 10–25 at% Mo. A binary Cr/Mo–Si phase diagram is generated in order to determine accurate annealing conditions and estimate the stability range of the metastable σ phase.

Hyaluronic Acid Prevents Fusion of Brain Tumor-Derived Spheroids and Selectively Alters Their Gene Expression Profile.

Hyaluronic acid (HA), a major glycosaminoglycan of the brain extracellular matrix, modulates cell behaviors through binding its receptor, Cd44. In this study, we assessed the influence of HA on high-grade brain tumors in vitro. The model comprised cell cultures derived from six rodent carcinogen-induced brain tumors, forming 3D spheroids prone to spontaneous fusion. Supplementation of the standard culture medium with 0.25% HA significantly inhibited the fusion rates, preserving the shape and size uniformity of spheroids. The 3D cultures were assigned to two groups; a Cd44lo group had a tenfold decreased relative expression of Cd44 than another (Cd44hi) group. In addition, these two groups differed by expression levels of Sox2 transcription factor; the correlation analysis revealed a tight negative association for Cd44 and Sox2. Transcriptomic responses of spheroids to HA exposure also depended on Cd44 expression levels, from subtle in Cd44lo to more pronounced and specific in Cd44hi, involving cell cycle progression, PI3K/AKT/mTOR pathway activation, and multidrug resistance genes. The potential HA-induced increase in brain tumor 3D models' resistance to anticancer drug therapy should be taken into account when designing preclinical studies using HA scaffold-based models. The property of HA to prevent the fusion of brain-derived spheroids can be employed in CNS regenerative medicine and experimental oncology to ensure the production of uniform, controllably fusing neurospheres when creating more accurate in vitro brain models.

Fischer-Tropsch to olefin reaction over Fe-based catalysts: Effect of preparation method and synergistic effect of Mn and Zr promoters

BackgroundDirect production of light olefins (basic chemical raw materials in the industrials) from syngas using promoted catalysts demonstrates great potential, because of their upgraded performances. MethodsIn this study, a series of Fe-based catalysts promoted by Mn and Zr were prepared by hydrothermal and microemulsion methods and applied to the Fischer-Tropsch reaction. To optimize the catalysts, response surface methodology combined with the central composite design was applied to three independent parameters of the synthesis method, weight percent of Zr promoter (2th promoter) and reaction temperature. To clarify the relationship between the synthesis methods, the synergistic effect of Zr and Mn promoters, and catalyst performance, in detail, different characterization analyses were studied, including XRD, BET, SEM-EDS, FESEM, TEM, H2-TPR, and CO-TPR. Significant findingsAccording to developed statistical equations, it was revealed that the synthesis method is the most influential parameter on CO% and O/P ratio. The experimental results indicated that Zr and Mn promoters had a negative synergistic effect on the CO% and O/P, but a positive one on the heavy hydrocarbons selectivities. The characterization results demonstrated that hydrothermal prepared FeMn catalyst, due to having uniform particle size distribution, cubic morphology, and better reduction at low temperature had highest CO%.