Size Dispersion Research Articles

Advanced X/γ-Ray-Shielding Materials Enabled by the In Situ Generation of Cerium-Tungsten Nanoparticles Within Regenerated Collagen Fibers.

Advanced X- and γ-ray-shielding materials are conventionally designed and fabricated via the uniform dispersion of high-Z elements into the substrate. These soluble high-Z elements considerably reduced the particle size of functional components; however, the as-obtained composites exhibited weak absorption region at 40-80keV and poor water resistance. To address these issues, such materials are fabricated by introducing cerium and tungsten into regenerated collagen fibers (RCFs) using a "dual impregnation-desolvation" strategy. The uniform dispersion of functional components is achieved via the in situ generation of cerium-tungsten nanoparticles (CeW NPs) under multiple impregnating and desolvating cycles; as a result, the CeW NPs achieved an ultrasmall particle size of 17.15nm. Benefiting from the ultrasmall particle size and uniform dispersion of CeW NPs, the fabricated CeW-RCF composites exhibit satisfactory X- and γ-ray-shielding capabilities with an ultrahigh mass attenuation coefficient (MAC) of 5.9cm2g-1 at 83keV, higher than that of lead plates. The CeW-RCF composites also exhibit outstanding mechanical strength, low density, and high air permeability, demonstrating their superior wearability. This work provides novel insights into the design and fabrication of advanced X- and γ-ray-shielding materials with high radiation-shielding performance and enhanced wearability.

Characterization and Antibacterial Activity of Silver Nanoparticles Synthesized from Oxya chinensis sinuosa (Grasshopper) Extract.

In this study, silver nanoparticles (AgNPs) were synthesized using a green method from an extract of the edible insect Oxya chinensis sinuosa (O_extract). The formation of AgNPs (O_AgNPs) was confirmed via UV-vis spectroscopy, and their stability was assessed using Turbiscan analysis. The size and morphology of the synthesized particles were characterized using transmission electron microscopy and field-emission scanning electron microscopy. Dynamic light scattering and zeta potential analyses further confirmed the size distribution and dispersion stability of the particles. The average particle size was 111.8 ± 1.5 nm, indicating relatively high stability. The synthesized O_AgNPs were further characterized using X-ray photoelectron spectroscopy (XPS), high-resolution X-ray diffraction (HR-XRD), and Fourier transform infrared (FTIR) spectroscopy. XPS analysis confirmed the chemical composition of the O_AgNP surface, whereas HR-XRD confirmed its crystallinity. FTIR analysis suggested that the O_extract plays a crucial role in the synthesis process. The antibacterial activity of the O_AgNPs was demonstrated using a disk diffusion assay, which revealed effective activity against common foodborne pathogens, including Salmonella Typhimurium, Escherichia coli, Staphylococcus aureus, and Bacillus cereus. O_AgNPs exhibited clear antibacterial activity, with inhibition zones of 15.08 ± 0.45 mm for S. Typhimurium, 15.03 ± 0.15 mm for E. coli, 15.24 ± 0.66 mm for S. aureus, and 13.30 ± 0.16 mm for B. cereus. These findings suggest that the O_AgNPs synthesized from the O_extract have potential for use as antibacterial agents against foodborne bacteria.

A Facile Strategy for PEGylated Nanoprodrug of Bortezomib with Improved Stability, Enhanced Biocompatibility, pH-Controlled Disassembly, and Release.

The therapeutic efficacy of bortezomib (BTZ) is often limited due to low solubility, poor stability in vivo and nonspecific toxicity. Herein, a kind of catechol-functionalized polyethylene glycol (mPEG-CA) is first synthesized and then mPEG-CA is readily used to conjugate with BTZ by the formation of dynamic boronate bonds to obtain PEGlyated BTZ prodrug (mPEG-CA-BTZ) with the ability of pH-controlled disassembly and drug release. The structure and morphology, physicochemical characteristics, drug loading, and release as well as in vitro cytotoxicity of mPEG-CA-BTZ nanoparticles are investigated in detail. The results demonstrated that mPEG-CA-BTZ can not only self-assemble into nanostructures with uniform size and stable dispersion in physiological pH condition (pH 7.4) but also respond to the tumor acid microenvironment and achieve pH-controlled BTZ release by acid-triggered cleavage of boronate bonds, decomposition of mPEG-CA-BTZ and thus disassembly of mPEG-CA-BTZ nanoparticles. mPEG-CA-BTZ nanoparticles are expected to have great potential as a promising nanoplatform for pharmaceutical formulations of BTZ to increase therapeutic efficacy and decrease side effects of BTZ. Considering the easily available and biocompatible excipients and simple preparation process, the strategy designed herein provides a facile and promising approach to synergistically integrate the function of PEGylation and pH-sensitiveness into boronic acid-containing small molecule pharmaceutical agents.

Pd nanoparticles on DUT-67-PZDC-derived N-doped carbon for efficient H2 generation from formic acid dehydrogenation

It is important to develop heterogeneous catalysts with high efficiency and stability to catalyze formic acid (FA, HCOOH) dehydrogenation. Herein, through pyrolysis of DUT-67-PZDC and etching in a hydrofluoric acid (HF) solution, the HF-etched N-doped carbon (HNDC) carrier was obtained. Palladium nanoparticles (Pd NPs), with an average particle size of 3.0 nm, were prepared on the HNDC support using a simple chemical co-reduction method. The optimized Pd/HNDC catalyst demonstrates excellent catalytic activity, the initial turnover frequency (TOF) value is 6001 h−1 at 50 °C with the incorporation of sodium formate (SF) as an additive, and the FA conversion and hydrogen (H2) selectivity could be up to 100%, which is comparable to the majority of MOF-derived heterogeneous catalysts published to date. Additionally, the Pd/HNDC can maintain good stability in five consecutive FA dehydrogenation runs with only a slight decrease. Such remarkable catalytic performance of Pd/HNDC is mainly ascribed to the unique structure of HNDC support with high surface area and hierarchical pore characteristic, the strong synergistic interaction between Pd NPs and the N sites on HNDC, as well as the ultrasmall size and high dispersion of Pd NPs as the catalytic active site. This work offers an efficient method for assembling highly active catalysts for FA dehydrogenation.

Unraveling the Formation of Ternary AgCuSe Crystalline Nanophases and Their Potential as Antibacterial Agents.

AgCuSe nanoparticles could contribute to the growth of strongly light-absorbing thin films and solids with fast ion mobility, among other potential properties. Nevertheless, few methods have been developed so far for the synthesis of AgCuSe nanoparticles, and those reported deliver nanostructures with relatively large sizes and broad size and shape distributions. In this work, a colloidal cation exchange method is established for the easy synthesis of AgCuSe NPs with ca. 8 nm diameters and narrow size dispersion. Notably, in this lower size range the conucleation and growth of two stoichiometric ternary compounds are generally observed, namely the well-known eucairite AgCuSe compound and the novel fischesserite-like Ag3CuSe2 phase, the latter being less thermodynamically stable as predicted computationally and assessed experimentally. An optimal range of Cu/Ag precursor molar ratio has been identified to ensure the growth of ternary nanoparticles and, more specifically, that of the metastable Ag3CuSe2 nanophase isolated for the first occasion. The attained size range for the material paves the way for utilizing AgCuSe nanoparticles in new ways within the field of biomedicine: the results obtained here confirm the antibacterial activity of the new Ag x Cu y Se z nanoparticles against Gram-positive bacteria, with significantly low values of the minimal inhibitory concentration.

Synthesis of Dumbbell-Like Heteronanostructures Encapsulated in Ferritin Protein: Towards Multifunctional Protein Based Opto-Magnetic Nanomaterials for Biomedical Theranostic

Dumbbell-like hetero nanostructures based on gold and iron oxides is a promising material for biomedical applications, useful as versatile theranostic agents due the synergistic effect of their optical and magnetic properties. However, achieving precise control on their morphology, size dispersion, colloidal stability, biocompatibility and cell targeting remains as a current challenge. In this study, we address this challenge by employing biomimetic routes, using ferritin protein nanocages as template for these nanoparticles’ synthesis. We present the development of an opto-magnetic nanostructures using the ferritin protein, wherein gold and iron oxide nanostructures were produced within its cavity. Initially, we investigated the synthesis of gold nanostructures within the protein, generating clusters and plasmonic nanoparticles. Subsequently, we optimized the conditions for the superparamagnetic nanoparticles synthesis through controlled iron oxidation, thereby enhancing the magnetic properties of the resulting system. Finally, we produce magnetic nanoparticles in the protein with gold clusters, achieving the coexistence of both nanostructures within a single protein molecule, a novel material unprecedented to date. We observed that factors such as temperature, metal/protein ratios, pH, dialysis, and purification processes all have an impact on protein recovery, loading efficiency, morphology, and nanoparticle size. Our findings highlight the development of ferritin-based nanomaterials as versatile platforms for potential biomedical use as multifunctional theranostic agents.

Kinetic stability and bioavailability of curcumin nanoemulsions stabilized with krill oil phospholipids

Curcumin is a phenolic compound with widely reported bioactive properties. However, its low water solubility leads to low stability and bioavailability. Krill oil (KO) is a rich source of phospholipids naturally structured with omega-3 fatty acids (FA) that emerges as a suggested vehicle for curcumin. This study was aimed to prepare curcumin nanoemulsions (NE) using KO phospholipids as a surfactant to improve the absorption of curcumin after oral ingestion. NE were formulated with i) purified krill phospholipids (PCK), and ii) NE with crude KO without the addition of co-surfactants. As a reference, a NE was formulated using soy phosphatidylcholine (PC). Using 8 % of PCK and 4 cycles of ultrasound, NE with unimodal particle size dispersion were formed. The physicochemical analysis of the NE was monitored for 70 days at 4 and 30 °C; the nanoemulsified curcumin followed first-order degradation kinetics with a half-life (t1/2) for PC, KO, and PCK of 396, 328, and 162 days, respectively. TBARS values reached a maximum of 30 μM for KO and PCK NE, but according to the ABTS method, they had better antioxidant activities (>4.9 μM Trolox). Concerning pharmacokinetics, KO NE displayed the best bioavailability data with an AUC of 684.54 ± 72.62 ng h/mL, increasing five times more its absorption with respect to non-nanoemulsified curcumin. According to our data, NEs can guarantee the stability of curcumin during storage at 4 °C and improve its absorption after oral intake. Indeed, self-emulsified KO NEs enhance the bioavailability of curcumin to the same or better extent than soy PC conventional, but with the advantage of providing functional ingredients (omega-3 FA and astaxanthin).

Impact of tip curvature and edge rounding on the plasmonic properties of gold nanorods and their silver-coated counterparts.

Colloidal solutions of gold nanorods and silver-coated gold nanorods were prepared. The seeded growth synthesis protocols were improved by adding a flocculation purification step. The resulting populations of pure gold nanorods and Au@Ag core-shell cuboids were characterized by very low dispersion in size and shape. UV-vis-near-infrared absorption measurements were performed on several batches of well-calibrated nano-objects, supported by calculations based on the discrete dipole approximation, allowed to highlight the impact of various morphological features on the optical response. In addition to the well-known effect of the nanorod aspect ratio on the shift of the longitudinal surface plasmon resonance mode, special attention was paid to changing either the rounding of the nanorod end-caps or that of the edges of the coating silver shell. Nanorods and cuboids were modeled as superellipsoids. This approach enabled us to model precisely their complex shapes using just a few simple parameters and analyze the evolution of their extinction spectra as a function of the rounding of their tips and edges. Such nano-objects are widely used for various applications in fields such as biomedical, biosensing, or surface-enhanced Raman spectroscopy, thus making it crucial to precisely assess the impact of each morphological feature for optimizing their performance.

Design and Optimization of Solid Lipid Nanoparticles for Enhanced Therapeutic Activity of Linagliptin.

To augment oral bioavailability, linagliptin (LGP) loaded solid lipid nanoparticles (SLNs) have been formed using the solvent evaporation technique of emulsification. Utilizing the Box Behken design (BBD), examining the relation between independent and dependent variables was possible. Particle size (PS), entrapment efficiency (EE), and in-vitro drug release (DR) studies were considered response factors, whereas the various concentrations of lipid carrier, surfactant, and co-surfactant were considered process variables for optimization. The design expert program was used to obtain the optimized batch. At 24 hours, it was discovered that the optimized batch expected responses for PS, %EE, and %DR were 105.83 nm, 81.19, and 96.69%, respectively. The observed PS, %EE, and %DR responses of the optimized batch at 24 hours were determined to be 101.36 nm, 80.56, and 96.31%, respectively. There is no interaction seen in the basic physical mixing of drug and polymer, according to the FTIR spectra of pure drugs, polymers, and drug and polymer mixtures. The optimized formulation’s average size was found to be 138 nm by the particle size analysis. Similarly, a value of 0.255 was found by the polydispersity index (PDI). This suggests that the SLN in the formulation has a homogeneous size dispersion. With a zeta value of -32.8 mV, stability is indicated. Linagliptin was effectively developed as a drug with a 24-hour sustained release. Wistar rats were used in the in-vivo evaluation of linagliptin SLN formulations. The drug bioavailability increased five times (a highly significant fivefold increase) in LGP-loaded SLNs (AUC0-t ≈ 134.5 μg*h/mL) compared to raw LGP (AUC0-t = 27.23 μg*h/mL).

Investigating the Biotic and Abiotic Drivers of Body Size Disparity in Communities of Non‐Volant Terrestrial Mammals

ABSTRACTAimThe species that compose local communities possess unique sets of functional and ecological traits that can be used as indicators of biotic and abiotic variation across space and time. Body size is a particularly relevant trait because species with different body sizes typically have different life history strategies and occupy distinct niches. Here we used the body sizes of non‐volant (i.e., non‐flying) terrestrial mammals to quantify and compare the body size disparity of mammal communities across the globe.LocationGlobal.Time PeriodPresent.Major Taxa StudiedNon‐volant terrestrial mammals.MethodsWe used IUCN range maps of 3982 terrestrial mammals to identify 1876 communities. We then combined diet data with data on climate, elevation and anthropogenic pressures to evaluate these variables' relative importance on the observed body size dispersion of these communities and its deviation from a null model.ResultsDispersion for these communities is significantly greater than expected in 54% of communities and significantly less than expected in 30% of communities. The number of very large species, continent, range sizes, diet disparity and annual temperature collectively explain > 50% of the variation in observed dispersion, whereas continent, the number of very large species, and precipitation collectively explain > 30% of the deviation from the null model.Main ConclusionsClimate and elevation have minimal predictive power, suggesting that biotic factors may be more important for explaining community body size distributions. However, continent is consistently a strong predictor of dispersion, likely due to it capturing the combined effects of climate, size‐selective human‐induced extinctions and more. Overall, our results are consistent with several plausible explanations, including, but not limited to, competitive exclusion, unequal distribution of resources, within‐community environmental heterogeneity, habitat filtering and ecosystem engineering. Further work focusing on other confounding variables, at finer spatial scales and/or within more causal frameworks is required to better understand the driver(s) of these patterns.

Preformulation studies of an emulsion containing commercially available argan oil

Background: Argan oil has gained popularity in recent years due to its potential anti-inflammatory and antioxidant properties. The present pre-formulation study sought to investigate the suitability of using commercially available argan oil as a unique pharmaceutical emulsion formulation for oral consumption. This research aimed to develop an efficient pre-formulation strategy for oil-in-water emulsion containing argan oil and optimize the formulation's optimum stability as a pharmaceutical dosage form. Methods: Various analytical and physical characterization techniques were employed in making an emulsion, such as organoleptic analysis, pH level, viscosity, particle size distribution, gravimetric test, and dye method test. The three formulations (A, B, and C) gave different results for the sizes of oil droplets, appearance, taste, and compatibilities. Results: Among the tested formulations, formulation A, containing 5 ml argan oil, exhibited a cloudy white appearance, hazelnut-like taste and texture, higher oil retention, and improved droplet size dispersion (0.58 μm - 116.21 μm). The results indicated that all three formulations have acidic pH values 4.82-5.84. Conclusion: Formulation A demonstrated notable attributes, making it the optimal choice for the oil-in-water emulsion containing argan oil. Addressing compatibility concerns and assessing sensory attributes, pH levels, and particle size distribution successfully achieved the desired pharmaceutical elegance, laying a promising foundation for developing stable and effective oral emulsions.

High-density integration of uniform sub-22 nm silicon nanowires for transparent thin film transistors on glass

Ultrathin catalytical silicon nanowires (SiNWs), grown as orderly arrays upon glass substrates, are ideal 1D channels for the construction of high-performance field effect transistors for low-power and high aperture/transparency electronics. In this work, a rather uniform growth integration of high-density ultrathin SiNWs has been accomplished directly on glass substrate at 290 °C, via an in-plane solid–liquid-solid mechanism. The indium (In) catalyst thickness deposited on the dense guiding terrace steps was identified as a key parameter to suppress the size dispersion of the In droplets, and thus enable a uniform growth of ultrathin SiNWs with diameters down to DNW=21.8 ± 1.8 nm, a close-to-unity guided growth rate and an excellent transparency > 90 % in spectrum ranging from 350 nm to 950 nm. Based on a convenient dry plasma etching and low-temperature passivation procedure, high-performance SiNW transistors have been successfully fabricated upon a dense array of parallel SiNWs as channels with a narrow NW-to-NW spacing of 100 nm. A high current ratio Ion/Ioff > 107, a low off-state current down to 0.1 pA, a steep subthreshold swing of SS∼120 mV dec-1 and excellent positive and negative bias stabilities have been demonstrated, as well as SiNW-based inverter logics that achieve a gain of 14.6 V/V under a drive voltage of 2.25 V. These results highlight the potential of catalytic SiNWs to serve as advantageous 1D channels for large-area display or transparent electronics.

Effect of the crystallographic orientation of the surface of single-crystal Si wafers on the endotaxial growth of NiSi2 nanoplates

A multi-technique analysis was used to investigate how the orientation of single-crystal Si wafer surfaces affects the size, shape and orientation of NiSi2 nanocrystals grown within the wafers through the thermal diffusion of Ni atoms from a nickel-doped thin film deposited on the surface. Nickel-doped thin films were prepared on silicon wafers with three distinct crystallographic orientations, [001], [110] and [111]. Three sets of samples were then annealed at 500, 600 and 700°C for 2 h. Regardless of crystallographic orientation or annealing temperature, NiSi2 nanoplates with a nearly hexagonal shape grew close to the external surface of the wafers, aligning their larger surfaces parallel to one of the planes of the Si{111} crystallographic form. The crystallographic orientation and annealing temperature in the 500–700°C range did not significantly affect the final values of the average diameter and thickness of the nanoplates. However, significant differences were noted in the number of nanoplates formed in Si wafers with different crystallographic orientations. The results indicate that these observed differences are correlated with the number of pre-existing defects in the wafers that influence the heterogeneous nucleation process. In addition, the average size and size dispersion were determined for pores at the surface of the Si wafers formed due to the etching process used for native oxide removal.

2LiBH4-MgH2 System Catalytically Modified with a 2D TiNb2O7 Nanoflake for High-Capacity, Fast-Response, and Long-Life Hydrogen Energy Storage.

To achieve large-scale hydrogen storage for growing high energy density and long-life demands in end application, the 2LiBH4-MgH2 (LMBH) reactive hydride system attracts huge interest owing to its high hydrogen capacity and thermodynamically favorable reversibility. The sluggish dehydrogenation kinetics and unsatisfactory cycle life, however, remain two challenges. Herein, a bimetallic titanium-niobium oxide with a two-dimensional nanoflake structure (2D TiNb2O7) is selected elaborately as an active precursor that in situ transforms into TiB2 and NbB2 with ultrafine size and good dispersion in the LMBH system as highly efficient catalysts, giving rise to excellent kinetic properties with long-term cycling stability. For the LMBH system added with 5 wt% 2D TiNb2O7, 9.8 wt% H2 can be released within 20 min at 400 °C, after which the system can be fully hydrogenated in less than 5 min at 350 °C and 10 MPa H2. Moreover, a dehydrogenation capacity of 9.4 wt% can be maintained after 50 cycles corresponding to a retention of 96%, being the highest reported to date. The positive roles of TiB2 and NbB2 for kinetics and recyclability are from their catalytic nucleation effects for MgB2, a main dehydrogenation phase of LMBH, thus reducing the apparent activation energy, suppressing the formation of thermostable Li2B12H12 byproducts, and inhibiting the hydride coarsening. This work develops an advanced LMBH system, bringing hope for high-capacity, fast-response, and long-life hydrogen energy storage.

Stem cell recruitment polypeptide hydrogel microcarriers with exosome delivery for osteoarthritis treatment

With the accelerated aging tendency, osteoarthritis (OA) has become an intractable global public health challenge. Stem cells and their derivative exosome (Exo) have shown great potential in OA treatment. Research in this area tends to develop functional microcarriers for stem cell and Exo delivery to improve the therapeutic effect. Herein, we develop a novel system of Exo-encapsulated stem cell-recruitment hydrogel microcarriers from liquid nitrogen-assisted microfluidic electrospray for OA treatment. Benefited from the advanced droplet generation capability of microfluidics and mild cryogelation procedure, the resultant particles show uniform size dispersion and excellent biocompatibility. Moreover, acryloylated stem cell recruitment peptides SKPPGTSS are directly crosslinked within the particles by ultraviolet irradiation, thus simplifying the peptide coupling process and preventing its premature release. The SKPPGTSS-modified particles can recruit endogenous stem cells to promote cartilage repair and the released Exo from the particles further enhances the cartilage repair performance through synergistic effects. These features suggest that the proposed hydrogel microcarrier delivery system is a promising candidate for OA treatment.

Silica particle size and polydispersity control from fundamental practical aspects of the Stöber method

Silica-based nanoparticles have been continuously investigated for their physical and chemical properties, which have made them adaptable for a wide range of scientific purposes, from adsorption in an aqueous medium to target-specific drug delivery in biological fluids. The achievement of these properties is, in general, possible by controlling the synthesis of the nanomaterial, and the Stöber method is one of the most commonly employed approaches for silica-based nanoparticles. In this study, experiments were carried out to investigate several parameters of the Stöber method for controlling the diameter and size dispersion of silica nanoparticles. The results of these experiments were supported by and contrasted with the theoretical aspects of silica particle nucleation and growth models. In this scenery, practical aspects of the Stöber Method such as the effects of variations in catalyst concentration, colloidal stability and drying approach on particle size and polydispersity were examined in detail for providing an organized basis of experimental and theoretical data about it for who aims at work with silica nanoparticle synthesis through the Stöber Method.

Integrating molecular-caged nano-hydroxyapatite into post-crosslinked PVA nanofibers for artificial periosteum

Artificial periosteum is deemed a novel strategy for inducing endogenous bone regeneration, but ideal periosteum substitutes achieved by orchestrating a biomimetic microenvironment for bone regeneration remain a significant challenge. Here, we design and fabricate a hybridized nanofiber-based artificial periosteum with boosted osteoinduction properties. Via a “molecular cage” biomineralization strategy, nano-hydroxyapatite (nano-HAp) with a controllable size (∼22 nm) and excellent dispersion serves as unique nano-additives for water-soluble polyvinyl-alcohol (PVA)-based artificial periosteum. The PVA/HAp composite is electrospun into nanofibers to replicate the extracellular-matrix-inspired nanostructure for inducing cell adhesion, proliferation, and fate manipulation. A simple post-crosslinking treatment is subsequently applied to further booster its mechanical strength (6.6 MPa) and swelling stability. The optimized sample of C-PVA/HAp (10 wt% nano-HAp) artificial periosteum features excellent biocompatibility and remarkable in vitro mineralization. Cell experiments demonstrate that its effectively boasted cell modulation for enhanced osteogenesis without the aid of growth factors, showing a possible activation of the ERK/MAPK signaling pathway. This work provides an effective strategy for designing novel HAp nano-additives and expands the possibility of biomimetic fabrication for more advanced nanofiber-based artificial periosteum.

Circulating extracellular vesicles in Systemic Lupus Erythematosus: physicochemical properties and phenotype

ObjectiveThis study aimed to identify the physicochemical and phenotypic characteristics of circulating Extracellular Vesicles (EVs) in the plasma of patients with SLE, with or without Lupus Nephritis (LN), and their...

Direct conversion of biogas to syngas over bimetallic nickel–cobalt supported on α-alumina catalysts

Syngas is an essential feedstock for many valuable chemicals, produced primarily by steam reformation of methane. Recently, dry reformation (reaction between methane and carbon dioxide) has gained importance as both the reactants are greenhouse gases (GHGs). However, dry reformation (DRM) produces syngas with a low H2/CO (<1.0). The DRM requires catalyst such as nickel supported on alumina, which results in higher coke. In this study, 6Ni–6Co/α-Al2O3 and 12Ni/α-Al2O3 catalysts were prepared by wetness impregnation. The catalysts were characterized using FESEM, XRD, XPS, BET, H2-TPR, NH3-TPD and H2-Chemisorption. The catalyst performance under DRM conditions were carried out in a fixed bed reactor at 20,000 ml/gcat.hr GHSV, between 600 °C and 700 °C, at atmospheric pressure. The performance of the catalysts was compared based on conversion of methane and carbon dioxide, hydrogen to carbon monoxide and coke deposition. The rates of consumption of methane carbon dioxide were found to be equal, and higher rates were observed for 6Ni–6Co/α-Al2O3, which is attributed to NiAl2O4/CoAl2O4 phase of active metals, higher surface area, smaller crystallite size and higher dispersion. This active phase of catalyst also responsible for higher rate of CO2 adsorption and reduced coke deposition. Highest H2/CO was found to be 1.26 for 6Ni–6Co/α-Al2O3.

Synthesis and characterization of selenium nanoparticles stabilized by Grifola frondosa polysaccharides and gallic acid conjugates

Selenium nanoparticles (SeNPs) are of interest for their versatility and low toxicity, but bare SeNPs are unstable and tend to aggregate and precipitate as black elemental Se, which limits the application of SeNPs. This study evaluated the physicochemical properties, physical stability, antioxidant activities and cytotoxicity of SeNPs stabilized by Grifola frondosa polysaccharides (GFPs) and GFPs-gallic acid conjugates (GFPs-GA). The results showed that the particle size (PZ), polymer index (PDI) and zeta potential (ZP) of the GFPs-SeNPs and GFPs-GA-SeNPs were 58.72 ± 0.53 nm, 0.11, −8.36 ± 0.21 mV and 61.80 ± 0.16 nm, 0.12, −9.37 ± 0.13 mV, respectively. Besides, the GFPs-SeNPs and GFPs-GA-SeNPs remained stable when stored at 4 °C for 70 days in darkness. SeNPs stabilized with GFPs have improved the antioxidant activity and selective toxicity to tumour cells. Interestingly, SeNPs stabilized with GFPs-GA further enhanced these biological activities. This work provided a simple and effective method to construct well-dispersed SeNPs in aqueous systems, demonstrating the important roles of GFPs and GFPs-GA in the size control, dispersion and stabilization of SeNPs. The prepared GFPs-SeNPs and GFPs-GA-SeNPs can serve as good selenium supplements and have potential prospects for antioxidant activity and tumour inhibition.