Surface Enrichment Research Articles

Insights into the Release Mechanisms of ITZ:HPMCAS Amorphous Solid Dispersions: The Role of Drug-Rich Colloids.

Understanding the dissolution mechanisms of amorphous solid dispersions (ASDs) and being able to link enhanced drug exposure with process parameters are key when formulating poorly soluble compounds. Thus, in this study, ASDs composed by itraconazole (ITZ) and hydroxypropylmethylcellulose acetate succinate (HPMCAS) were formulated with different polymer grades and drug loads (DLs) and processed by spray drying with different atomization ratios and outlet temperatures. Their in vitro performance and the ability to form drug-rich colloids were then evaluated by a physiologically relevant dissolution method. In gastric media, drug release followed a diffusion-controlled mechanism and drug-rich colloids were not formed since the solubility of the amorphous API at pH 1.6 was not exceeded. After changing to intestinal media, the API followed a polymer dissolution-controlled release, where the polymer rapidly dissolved, promoting the immediate release of API and thus leading to liquid-liquid phase separation (LLPS) and consequent formation of drug-rich colloids. However, the release of API and polymer was not congruent, so API surface enrichment occurred, which limited the further dissolution of the polymer, leading to a drug-controlled release. ASDs formulated with M-grade showed the highest ability to maintain supersaturation and the lowest tendency for AAPS due to its good balance between acetyl and succinoyl groups, and thus strong interactions with both the hydrophobic drug and the aqueous dissolution medium. The ability to form colloids increased for low DL (15%) and high specific surface area due to the high amount of polymer released until the occurrence of API surface enrichment. Even though congruent release was not observed, all ASDs formed drug-rich colloids that were stable in the solution until the end of the dissolution study (4 h), maintaining the same size distribution (ca. 300 nm). Drug-rich colloids can, in vivo, act as a drug reservoir replenishing the drug while it permeates. Designing ASDs that are prone to form colloids can overcome the solubility constraints of Biopharmaceutics Classification System (BCS) II and IV drugs, posing as a reliable formulation strategy.

Asymmetric poly (vinyl alcohol)/Schiff base network framework hybrid pervaporation membranes for ethanol dehydration

Asymmetric pervaporation mixed matrix membranes (MMMs) were constructed by incorporating a low-density Schiff base network framework (SNW-1) into a relative high-density poly(vinyl alcohol) (PVA) matrix. A large amount of SNW-1nanoparticles enrichedontothemembrane surfacedue to the buoyancy effect. Meanwhile, a small amount of SNW-1 nanoparticles still remained in PVA body due to the slow solvent evaporation. This asymmetric distribution in PVA body gives the membrane three larger advantages. Firstly, the surface enrichment of SNW-1, which contains many nitrogen-groups, enhances membrane’s hydrophilicity and swelling resistance significantly. Secondly, the interfacial interactions could exit between SNW-1 and PVA matrix, thereby improving the membrane’s mechanical stability and heat-resistance property. Thirdly, the SNW-1 nanoparticles with water-selective pore structures in PVA body or on membrane surfaces could all increase membrane separation performances. As a result, for 90 wt% ethanol aqueous, the prepared MMMs containing only 1.5 wt% SNW-1 owned a separation factor of 751 and a total flux of 254 g/m2h. Furthermore, the MMMs exhibited an excellent long-term operating stability. After running 120 h at 75 °C, the total flux and separation factor still remained at their initial values. The prepared MMMs show a potential for ethanol or other alcohols dehydration applications.

Paleoproterozoic manganese oxide precipitation in oxic seawater surface and reductive enrichment in anoxic seafloor

Accelerated precipitation of Mn-rich rocks in the early Paleoproterozoic ocean is considered to reflect the irreversible rise of oxygen in the atmosphere during the Great Oxidation Event (GOE), 2.501–2.220 billion years ago. But the precipitation conditions, pathways, mechanisms, and linkages to ocean redox, broadly remain unresolved. The Lagoa do Riacho Mn deposit in Borborema Province, northeastern Brazil, Ceará state, consists mainly of manganese-rich and manganese-poor silicates deposited during the GOE epoch. Negative Ce anomalies in the manganese-poor silicates point to the scavenging of Ce3+ onto Mn-oxyhydroxide reactive surfaces in the oxygenated surface waters. In contrast, samples with positive Ce anomalies, predominantly associated with the manganese-rich silicates, indicate a reductive dissolution of Mn-oxyhydroxides across a redoxcline, enriching the anoxic bottom water with Ce and Mn2+. A paleoredox reconstruction based on couple Mn, Mo, and U systematics supports the existence of the proposed Mn-oxide redox shuttle that enriched the anoxic sediment pile with Mn precipitated from the oxygenated shallow surface waters. This study uncovers a unique pathway in Paleoproterozoic Mn mineralization involving the transfer of Mn oxides from an oxygenated upper ocean reservoir to a predominantly deep anoxic silicate reservoir that was subsequently metamorphosed. The proposed Mn oxide sink switch mechanism is different from the commonly reported reductive transfer of Mn to a diagenetic carbonate sink during the Paleoproterozoic.

Surface Functionality-Regulated and Entropy-Driven Thermodynamics of the Formation of Coordination Nanocages.

Coordination nanocages (CNCs) are under intense research in nanoscience and supramolecular chemistry for their enriched surface functionalities and micro-porosity; however, the understanding of their formation mechanism is still poor due to the difficulty in probing their solution structures. Herein, the CNC formation process from the coordination complexation of the macromolecular isophthalic acid (IPA) ligand and Cu2+ is studied via isothermal titration calorimetry, and its entropy-driven feature is revealed to be originated from the collapse of solvation layers of the assembly units. The CNC formation is thermodynamically less favored with smaller binding constants when the sizes of macromolecular IPA ligands are larger, which originated from the space crowding of macromolecules of the ligands on CNC surfaces and the resulting entropy loss of polymer chain conformations. Meanwhile, the chemical equilibrium of CNC formation can be tuned upon altering the Cu2+/IPA ratio, and the yield of CNCs, suggested from size exclusion chromatography studies, decreases when excessive Cu2+ is applied, providing guidelines for CNC design and synthesis.

Hierarchical flower-like architecture of nickel phosphide anchored with nitrogen-doped carbon quantum dots and cobalt oxide for advanced hybrid supercapacitors

The exploitation of hybrid supercapacitors with excellent electrochemical properties is of great significance for energy storage systems. Herein, a three-dimensional hierarchical flower-like architecture of nickel phosphide (Ni2P) decorated with nitrogen-doped carbon quantum dots (N-CQDs) and cobalt oxide (Co3O4) is constructed by an effective two-step hydrothermal strategy followed by in situ phosphorization process. Introducing N-CQDs with superior electrochemical characteristics can not only induce the formation of N-CQDs deposited nickel hydroxide (Ni(OH)2) flower-like architecture but also significantly enhance the electrochemical features of Ni(OH)2 nanosheets. After combination with Co3O4 nanoparticles and phosphorization treatment, an advanced cathode of Ni2P/Co3O4/N-CQDs with enriched surface phosphate ions is obtained, which possesses an ultra-high capacity of 1044 C g−1 (2088 F g−1) at 1 A g−1 with a splendid rate capacity of 876 C g−1 (1752 F g−1) at 20 A g−1. Moreover, a device assembled by Ni2P/Co3O4/N-CQDs hierarchical flower-like architecture and p-phenylenediamine functionalized reduced graphene oxide (PPD/rGO) nanosheets depicts a commendable energy density of 53.5 Wh kg−1 at 772.9 W kg−1. This work provides a novel hierarchical multi-component electrode material with decent electrochemical capacities for hybrid supercapacitors, which has a broad prospect in energy storage devices.

Gas and dust from extremely metal-poor AGB stars

Context. The study of stars that evolve through the asymptotic giant branch (AGB) proves crucial in several astrophysical contexts because these objects provide important feedback to the host system in terms of the gas that is poured into the interstellar medium after being exposed to contamination from nucleosynthesis processes, and in terms of the dust that forms in their wind. Most of the studies conducted so far have been focused on AGB stars with solar and sub-solar chemical composition, whereas the extremely metal-poor domain has been poorly explored. Aims. We study the evolution of extremely metal-poor AGB stars with metallicities down to [Fe/H] = −5 to understand the main evolutionary properties and the efficiency of the processes able to alter their surface chemical composition, and to determine the gas and dust yields. Methods. We calculated two sets of evolutionary sequences of stars in the 1−7.5 M⊙ mass range that evolved from the pre-main sequence to the end of the AGB phase. To explore the extremely metal-poor chemistries, we adopted the metallicities Z = 3 × 10−5 and Z = 3 × 10−7, which correspond to [Fe/H] = −3 and [Fe/H] = −5, respectively. The results from stellar evolution modelling were used to calculate the yields of the individual chemical species. We also modelled dust formation in the wind to determine the dust produced by these objects. Results. The evolution of AGB stars in the extremely metal-poor domain we explored proves highly sensitive to the initial mass of the star. M ≤ 2 M⊙ stars experience several third-dredge-up events, which favour the gradual surface enrichment of 12C and the formation of significant quantities of carbonaceous dust, ∼0.01 M⊙. The 13C and nitrogen yields are found to be significantly smaller than in previous explorations of low-mass metal-poor AGB stars because the proton ingestion episodes experienced during the initial AGB phases are weaker. M ≥ 5 M⊙ stars experience hot bottom burning, and their surface chemistry reflects the equilibria of a very advanced proton-capture nucleosynthesis; little dust production takes place in their wind. Intermediate-mass stars experience both third dredge-up and hot bottom burning: they prove efficient producers of nitrogen, which is formed by proton captures on 12C nuclei of primary origin dredged up from the internal regions.

The influence of surface modification on the optical and capacitive properties of NiO nanoparticles synthesized via surfactant-assisted coprecipitation

Material design and surface properties are considered as the main challenges towards the fabrication of a well-functionalized and stable device. In this work, surface-functionalized mesoporous NiO nanoparticles are synthesized via a facile one-pot precipitation method using sodium dodecyl sulfate and urea at 80 °C. The surface modification takes place via the addition of different bases such as NH4OH, NaOH, or K2HPO4 and the mechanism of NiO formation is highlighted. XRD verifies the formation of NiO as a major phase. IR proves the surface modification of NiO by sulfur, carbon, and nitrogen. Interestingly, ultrathin Ni(OH)2/NiO nanosheets of graphene-like shape are formed for the samples prepared by NH4OH demonstrating an enhancement in the specific capacitance, making it an attractive material for supercapacitors. On the other hand, mixed-shaped nanoparticles of ammine enriched surface are formed for the samples treated with NaOH demonstrating unusual ferromagnetic behavior and causing a narrowing in the band gap for NiO. XPS confirms the existence of sodium and potassium on the NiO surface, which improve the CO2 selective adsorption. Thus, surface functionalization is found to play a significant role in tuning the electronic, optical, and magnetic properties of NiO providing new future perspectives towards different applications.

Effects of L-leucine on the properties of spray-dried swellable microparticles with wrinkled surfaces for inhalation therapy of pulmonary fibrosis

Swellable microparticles (SMs) provide a potential strategy for achieving sustained inhalation therapy. However, spray dried SMs are highly hygroscopic, exhibiting poor flowability and dispersibility properties. This study aimed at determining whether L-leucine (LL) can improve aerosolization performance of SMs with wrinkled surface and its potential mechanisms. Cryptotanshinone was co-spray dried with chitosan and LL (0–40%, mass fraction in carrier materials), after which the production yield, particle size, density, encapsulation efficiency, morphology, cohesion, crystallinity, surface LL distribution, hygroscopicity, water content and in vitro aerosolization performance of the developed formulations were characterized. In addition, we determined whether LL, as a hydrophobic amino acid, would impair swellability and macrophage phagocytosis of SMs. The possible impact of LL on in vitro drug release, cytotoxicity and anti-fibrosis effects on MRC-5 cells was also investigated. As the LL content increased, LL began to crystallize. At 7.5% LL, water content and hygroscopicity of the SMs were at their lowest. Moreover, at 7.5% LL, surface enrichment increased rapidly after which it achieved a comparatively complete coverage at 20–40% LL. However, LL ≥ 20% caused the formation of over-wrinkled, even dimpled or hollow particles, which significantly deteriorated powder properties. Optimum aerosolization performance was obtained at 10% LL, irrespective of its crystallization behavior, accompanied by the lowest cohesion, optimal flowability and production yield, and without impaired swellability, macrophage uptake and anti-fibrosis efficacy. The optimal formulation did not exhibit optimum surface LL coverage, implying that improvement of aerosolization performance of wrinkled SMs by LL not simply depended on its surface enrichment, but its significant influence on morphology and on related powder properties as well.

Sectoral and growth rate control on elemental uptake by individual calcite crystals

Heterogeneous distribution of trace elements (impurities) within individual calcite crystals is a phenomenon commonly observed in natural and laboratory systems. Changes in thermodynamic intensive parameters (mostly chemical potential and temperature) cannot always explain the inhomogeneous impurity patterns in calcite crystals and it has been suggested that growth rate and crystallographic orientation may exert strong effects on elemental incorporation into calcite. In addition, there are a number of experimental studies on micro-scale element (E) distribution between non-equivalent pairs of calcite vicinal faces (known as sectoral zoning); however, the variability of partition coefficients (e.g., KE = (E/Ca)calcite/(E/Ca)fluid) within individual crystals remains undetermined.In this study, we have extended the work on elemental distribution between crystal sectors to evaluation of partition coefficients of trace and minor elements (Li, B, Mg, and Sr) in calcite crystal faces (10–14) and (01−12), whose growth rates were assessed. Growth entrapment model (GEM) and lattice strain theory were applied to explain KE heterogeneity by varying near-surface diffusivity of Mg and Sr and by varying surface enrichment factor for Li, B, Mg, and Sr. Decoupling of sectoral and growth rate effects reveals that sectoral zoning plays a key role in elemental distribution. More specifically, KLi and KB vary by more than one order of magnitude and KMg varies by a factor of two within individual crystal faces. Strontium sectoral distribution is different from those of Li, B, and Mg and KSr varies by up to a factor of two. These behaviors likely reflect different mechanisms of incorporation of Li, B, Mg, and Sr into calcite.

Green Production of Phthalic Anhydride from Biobased Furan and Maleic Anhydride by an Acid Resin Catalyst

The production of chemicals such as phthalic anhydride (PA) from renewable biomass is of crucial significance for sustainable social development. Herein, we demonstrate that a 99.0 mol % yield of PA can be achieved from a Diels–Alder adduct of furan and maleic anhydride on an acid resin catalyst. The active sites on the catalyst were produced by pretreating the resin with acetic anhydride. The excellent performance of the resin catalyst is attributed to its surface enrichment effect on the reactant and good ability to suppress the side reactions. Moreover, the catalyst deactivation mechanism was clarified to be the destruction of the resin skeleton during the reaction. These results will provide a practical route for the future industrial production of PA from renewable biomass.

H2O-assisted O2 reduction by H2 on Pt and PtAu bimetallic nanoparticles: Influences of composition and reactant coverages on kinetic regimes, rates, and selectivities

Hydrogen peroxide (H2O2) can replace hazardous oxidants in industrial processes but is currently too expensive for many such applications. While direct synthesis of H2O2 (H2 + O2 → H2O2) may reduce costs in comparison to incumbent technology, current catalysts lack the requisite stability and selectivity. Here, we examine the direct synthesis of H2O2 on bimetallic Pt1Aux (0 ≤ x ≤ 230) and Pt catalysts at steady-state in pure water and relate kinetic parameters for H2O2 and H2O formation to possible active site structures informed by complementary characterization methods. X-ray photoelectron spectra show significant Pt surface enrichment compared to the bulk composition. Analysis of infrared spectra of mixed monolayers of 12CO* and 13CO* indicate that Pt and Au form substitutional surface alloys. The Pt1Aux nanoparticles with the greatest mole fractions of Au predominantly expose Pt monomers (i.e., isolated Pt atoms), yet Pt atoms exposed upon all these nanoparticles possess electronic structures distinct from bulk Pt. Despite these differences, rate measurements are consistent with product formation through proton-electron transfer pathways for all Pt1Aux catalysts. In situ XAS indicate that Pt remains metallic during H2O2 synthesis. Under the most oxidizing conditions, selectivities toward H2O2 increase strongly with the Au to Pt ratio from 2% for monometallic Pt to 85% for Pt1Au170. However, selectivities are similar among all catalysts within reducing conditions. Comparisons of apparent activation enthalpies for the formation of H2O2 and H2O across these catalysts and the range of conditions suggest that Pt monomers within Au provide the greatest selectivities for H2O2 formation, because these active sites present high barriers for O-O bond rupture. Selectivities decrease with increasing ratios of H2 to O2 pressures, because Pt atoms aggregate and form oligomers that readily dissociate dioxygen intermediates. The combined use of spectroscopy, kinetics, and concepts employed in reaching these conclusions take inspiration from the legacy of Prof. Michel Boudart, and specifically his elegant methods for interrogating bimetallic catalysts.

Engineering the active sites tuned MoS2 nanoarray structures by transition metal doping for hydrogen evolution and supercapacitor applications

Extensive investigations have been made over the past two decades on the two-dimensional molybdenum sulfide (MoS2) since their dominating characteristics for the various applications including electrocatalysis and energy storage. Albeit MoS2 possesses the plentiful active sulfur edges, but their deficient inactive facets lead the poor conductivity and low efficiency. In this work, we attempted to activate more active sites by the insertion of doping transition metals such as nickel (Ni), copper (Cu) and iron (Fe) into MoS2 matrix. A facile chemical precipitation methodology was used to prepare the greatly active Fe, Cu and Ni metal doped MoS2 nanoarrays for hydrogen evolution and supercapacitors. Microscopic studies revealed the tuned morphology composed of nanoarrays structured domains of grains for metals doped MoS2 with the vertically aligned layers and extended layer spacing. The modified morphological properties, enriched surface area and plentiful active edges were apparently established for the metal doped MoS2. Hydrogen evolution results revealed that the improved electrocatalytic activity for Fe doped MoS2 nanoarrays with the low overpotentials, small Tafel slopes and unremitting reactions over 24 h in the acid and alkaline solution. The highly porous structured Cu doped MoS2 nanostructures owned the maximum capacitance of 353 F·g-1 at 1 A·g-1 current density with an admirable retaining capacity of ~94% after 5000 cycles.

Role of Hydration in Magnesium versus Calcium Ion Pairing with Carboxylate: Solution and the Aqueous Interface

The binding of group II metal cations such as Ca2+ and Mg2+ has been largely categorized as electrostatic or ionic using carboxylate symmetric and asymmetric stretching frequency assignments that have been historically used with little regard for the solvation environment of aqueous solutions. However, given the importance of these cations and their binding mechanisms related to biological function and in revealing surface enrichment factors for ocean to marine aerosol transfer, it is imperative that a deeper understanding be sought to include hydration effects. Here, infrared reflection-absorption and Raman spectra for surface and solution phase carboxylate binding information, respectively, are compared against bare (unbound) carboxylate and bidentate Zn2+:carboxylate spectral signatures. Spectral non-coincidence effect analysis, temperature studies, and spectral and potential of mean force calculations result in a concise interpretation of binding motifs that include the role of mediating water molecules, that is, contact and solvent-shared ion pairs. Calcium directly binds to the carboxylate group in contact ion pairs where magnesium rarely does. Moreover, we reveal the dominance of the solvent-shared ion pair of magnesium with carboxylate at the air-water interface and in solution.

The intermediate neutron capture process

Context. Carbon-enhanced metal-poor (CEMP) r/s-stars show surface-abundance distributions characteristic of the so-called intermediate neutron capture process (i-process) of nucleosynthesis. We previously showed that the ingestion of protons in the convective helium-burning region of a low-mass low-metallicity star can explain the surface abundance distribution observed in CEMP r/s stars relatively well. Such an i-process requires detailed reaction network calculations involving hundreds of nuclei for which reaction rates have not yet been determined experimentally. Aims. We investigate the nuclear physics uncertainties affecting the i-process during the asymptotic giant branch (AGB) phase of low-metallicity low-mass stars by propagating the theoretical uncertainties in the radiative neutron capture cross sections, as well as the 13C(α,n)16O reaction rate, and estimating their impact on the surface-abundance distribution. Methods. We used the STAREVOL code to follow the evolution of a 1 M⊙ [Fe/H] = − 2.5 model star during the proton ingestion event occurring at the beginning of the AGB phase. In the computation, we adopt a nuclear network of 1160 species coupled to the transport processes and different sets of radiative neutron capture cross sections consistently calculated with the TALYS reaction code. Results. It is found that considering systematic uncertainties on the various nuclear ingredients affecting the radiative neutron capture rates, surface elemental abundances are typically predicted within ±0.4 dex. The 56 ≲ Z ≲ 59 region of the spectroscopically relevant heavy-s elements of Ba-La-Ce-Pr as well as the r-dominated Eu element remain relatively unaffected by nuclear uncertainties. In contrast, the inclusion of the direct capture contribution impacts the rates in the neutron-rich A ≃ 45, 100, 160, and 200 regions, and the i-process production of the Z ≃ 45 and 65–70 elements. Uncertainties in the photon strength function also impact the overabundance factors by typically 0.2–0.4 dex. Nuclear level densities tend to affect abundance predictions mainly in the Z = 74 − 79 regions. The uncertainties associated with the neutron-producing reaction 13C(α,n)16O and the unknown β-decay rates are found to have a low impact on the overall surface enrichment. Conclusions. The i-process nucleosynthesis during the early AGB phase of low-metallicity low-mass stars remains sensitive to nuclear uncertainties, substantially affecting theoretical predictions of still unknown radiative neutron capture cross sections. Improved descriptions of direct neutron capture based on shell model calculations or experimental constraints from (d, p) reactions could help to decrease the uncertainties in the estimated rates. Similarly, constraints on the photon strength functions and nuclear level densities, for example through the Oslo method, in the neutron-rich region of A ≃ 100 and 160 would increase the predictive power of the present simulations.

N-Butane, iso-Butane and 1-Butene Adsorption on Imidazolium-Based Ionic Liquids Studied with Molecular Beam Techniques.

The interaction of molecules, especially hydrocarbons, at the gas/ionic liquid (IL) surface plays a crucial role in supported IL catalysis. The dynamics of this process is investigated by measuring the trapping probabilities of n‐butane, iso‐butane and 1‐butene on a set of frozen 1‐alkyl‐3‐methylimidazolium‐based ILs [C n C1Im]X, where n=4, 8 and X−=Cl−, Br−, [PF6]− and [Tf2N]−. The decrease of the initial trapping probability with increasing surface temperature is used to determine the desorption energy of the hydrocarbons at the IL surfaces. It increases with increasing alkyl chain length n and decreasing anion size for the ILs studied. We attribute these effects to different degrees of alkyl chain surface enrichment, while interactions between the adsorbate and the anion do not play a significant role. The adsorption energy also depends on the adsorbing molecule: It decreases in the order n‐butane>1‐butene>iso‐butane, which can be explained by different dispersion interactions.

Oxygen vacancies-enriched Ta-doped Bi2WO6 with Pt as cocatalyst for boosting the dehydrogenation of benzyl alcohol in water

Selective photocatalytic oxidation of alcohols into value-added aldehydes or ketones is a promising alternative for alcohol oxidation concerning the mild reaction conditions and the controllable selectivity. To increase the activity, defective Bi2WO6 with abundant oxygen vacancies (OVs) was synthesized via substitution of W by Ta. The resulting Ta-doped Bi2WO6 loaded with Pt nanoparticles as co-catalyst efficiently converted aromatic and aliphatic alcohols into the corresponding carbonyl compounds with high selectivity (>99%) in aqueous solution under visible-light irradiation and anaerobic conditions, with equivalent H2 as a coupled product. The optimal amount of benzyl alcohol converted by the Ta-doped catalyst was two times higher than that of the undoped catalyst. Surface OVs were found to favor the dissociative adsorption of the alcohols and to prolong the life time of the charge carriers. More importantly, isotopic labelling experiments confirmed that over Pt-loaded pristine undoped Bi2WO6, the coupled H2 product results from water reduction, while over Pt-loaded Ta-doped Bi2WO6, the produced H2 originates from benzyl alcohol, implying that benzyl alcohol can be photo-oxidized via a complete dehydrogenation pathway. Thus, enriched surface OVs in photocatalysts can activate α-C-H bonds in alcohols, boosting the photocatalytic oxidation performance.

Chemical and biological tracking in decentralized sanitation systems: The case of artificial constructed wetlands

Given that the social and economic sustainability of rural areas is highly based on the protection of natural resources, biodiversity and human health, simple-operated and cost-effective wastewater treatment systems, like artificial constructed wetlands (CWs), are widely proposed for minimizing the environmental and human impact of both water and soil pollution. Considering that the optimization of wastewater treatment processes is vital for the reduction of effluents toxic potential, there is imperative need to establish appropriate management strategies for ensuring CW performance and operational efficiency. To this end, the present study aimed to assess the operational efficiency of a horizontal free water surface CW (HFWS-CW) located in a world heritage area of Western Greece, via a twelve-month duration Toxicity Identification Evaluation (TIE)-like approach, including both chemical and biological tracking tools. Conventional chemical tracking, by means of pH, conductivity, total COD, and nitrogen-derived components, like nitrates and ammonia–nitrogen, were monthly recorded in both influents and effluents to monitor whether water quality standards are maintained, and to assess potent CW operational deficiencies occurring over time. In parallel, Whole Effluent Toxicity (WET) bioassays were thoroughly applied, using freshwater algae and higher plant species (producers), crustaceans and rotifers (consumers), as well as human lymphocytes (in terms of Cytokinesis Block Micronucleus assay) to evaluate the acute and short-term toxic and hazardous potential of both influents and effluents. The integrated analysis of abiotic (physicochemical parameters) and biotic (toxic endpoints) parameters, as well as the existence of “cause-effect” interrelations among them, revealed that CW operational deficiencies, mainly based on poorly removal rates, could undermine the risk posed by treated sewage. Those findings reinforce the usage of WET testing, thus giving rise to the importance of applying appropriate water management strategies and optimization actions, like oxygen enrichment of surface and bottom of HFWS-CW basins, expansion of the available land, the enhancement of bed depth and seasonal harvesting of plants, for ensuring sewage quality, in favor of water resources protection and sustainable growth in rural areas.

Shape impact of nanostructured ceria on the dispersion of Pd species

The shape impact of nanostructured ceria on the dispersion of Pd species was investigated by analyzing the atomic configuration and the bonding environment of Pd species over spherical and cubic ceria particles, using STEM and XPS. Amorphous Pd particles of about 2.0 nm, with a substantial amount of tiny Pd species, dispersed on spherical ceria, primarily due to the enriched surface oxygen vacancies that bonded the Pd species tightly. While faceted Pd particles of about 2.9 nm located on cubic ceria with distinct interfaces where Pd atoms embedded into the ceria lattice. The crystalline Pd particles on ceria cubes were highly active and stable for methane combustion that occurred on the metal surface via a facile PdO/Pd redox cycle; while the amorphous Pd particles on spherical ceria particles were featured by a significantly higher activity and stability towards CO oxidation, where the Pd-ceria interface served as the active sites.

Effect of Lipidic Excipients on the Particle Properties and Aerosol Performance of High Drug Load Spray Dried Particles for Inhalation

High drug load inhalable particles were prepared by co-spray drying a hydrophobic, crystalline, small molecule drug with various lipid or phospholipid excipients at a 9:1 molar ratio to understand the primary drivers of aerosol performance. The effect of excipient structure on solid-state, surface characteristics, and aerodynamic performance of the co-spray dried particles was studied while keeping the spray drying parameters constant. Spray drying of the drug with lipids produced crystalline drug particles, whereas phospholipids produced partially amorphous drug particles. All of the co-spray dried particles were nearly spherical with a smooth surface, except for the spray dried drug particles without excipients – which showed the presence of rough crystals on the surface. All co-spray dried particles showed surface enrichment of the excipient. The surface enrichment of the phospholipids was higher compared to the lipids. Co-spray dried particles that showed higher surface enrichment of excipients showed improved aerosol performance. In comparing all the excipients studied, distearyolphosphatidylcholine (DSPC) showed maximum enrichment on the particle surface and thereby significantly improved aerosol performance. This study demonstrated that the addition of small amounts of lipid excipients during spray drying can change surface morphology, composition, and cohesion, impacting aerosol performance of drugs.

Facile controlled formation of CoNi alloy and CoO embedded in N-doped carbon as advanced electrocatalysts for oxygen evolution and zinc-air battery

Constructing Schottky barrier of alloy/metal oxide interfaces is an emerging approach to design electrocatalysts with desired performance. Herein, a nitrogenous organic modified bimetal layered hydroxide salts (LHS) precursor is used to prepare CoNi alloy and CoO coupled nitrogen-doped carbon (NC) hybrids on carbon paper (CP) via a one-step pyrolysis at only 500 °C. Through adjusting the metal molar ratio in LHS precursor and the pyrolysis temperature, CoO is in-situ produced during pyrolysis. Since both alloy and metal oxide possess potential oxygen evolution reaction activity, the resulting CoNi-CoO@NC/CP exhibits enriched electrochemical active surface area, small overpotential (309 mV) at current density of 10 mA cm−2, low Tafel slope (67.7 mV dec−1), and good durability for 64 h at ∼20 mA cm−2 in 1.0 M KOH. Furthermore, a zinc-air battery based on this catalyst shows a high specific power of 96.2 W gcat−1, which exceeds that of conventional RuO2+Pt/C catalyst (66.8 W gcat−1). This work provides an appealing approach for the development of highly efficient alloy/metal oxide electrocatalysts for rechargeable metal-air battery.