Oxalic acid-assisted preparation of LTO-carbon composite anode material for lithium-ion batteries.

This study presents an oxalic acid-assisted method for synthesizing spinel-structured lithium titanate (Li4Ti5O12; LTO)/carbon composite materials. The Ag-doped LTO nanoparticles (NPs) are synthesized via flame spray pyrolysis (FSP). The synthesized material is used as a precursor for synthesizing the LTO-NP/C composite material with chitosan as a carbon source and oxalic acid as an additive. Oxalic acid improves the dissolution of chitosan in water as well as changes the composition and physical and chemical properties of the synthesized LTO-NP/C composite material. The oxalic acid/chitosan ratio can be optimized to improve the electrochemical performance of the LTO-NP/C composite material, and the electrode synthesized with a high mass loading ratio (5.44 mg cm-2) exhibits specific discharge capacities of 156.5 and 136 mAh g-1at 0.05 C- and 10 C-rate currents, respectively. Moreover, the synthesized composite LTO-NP/C composite material exhibits good cycling stability, and only 1.7% decrease in its specific capacity was observed after 200 charging-discharging cycles at 10 C-rate discharging current.

Aerosol processing technique for the synthesis of mixed-phase copper on carbon catalyst: insights into CO2adsorption and photocatalytic activity.

In this study, spray pyrolysis; an aerosol processing technique was utilized to produce a mixed-phase copper on carbon (Cu/CuxO@C) catalyst. The catalyst production was performed via chemical reduction of copper nitrate by a reducing sugar, i.e. glucose, using aqueous solution. The physical and chemical properties of the produced particles was assessed using various characterization techniques. The synthesis temperature had pronounced effect on the final particles. Since CO2adsorption onto the catalyst is an important step in catalytic CO2reduction processes, it was studied using thermogravimetric and temperature programmed desorption techniques. Additionally, photocatalytic activity of the particles was evaluated by gas-phase oxidation of acetylene gas which revealed excellent activity under both UV and visible light irradiation indicating the possible use of wider range of the solar spectrum.

Toxicological and microbiological characterization of cow stable dust.

Exposure to farm environment has been shown to both protect from allergic diseases and increase the risk of respiratory syndromes. Mechanisms have been previously investigated by using farm dust extracts or specific components of dust. The use of authentic farm dust would better reflect the natural exposure. The aim of our study was to highlight the importance of proper assessment of the cow stable dust characteristics before conducting further investigations. For this purpose, we characterized microbiome and size distribution of unprocessed cow stable dust and its toxicological properties, as they have been often overlooked in search of protective factors. Stable dust samples from four Finnish dairy farms were collected by utilizing two different collection methods. Toxicological potential was analysed by stimulating co-cultures of lung epithelial and macrophage-like cells with dust. Size and mass distributions of airborne particles in the stables and bacterial and fungal microbiota of the dust were analysed. Stimulation with dust did not affect viability, but heightened oxidative stress responses and cytokine secretion, and slightly reduced the metabolic activity. There were a few differences in responses between farms, however, the differences were mainly in the intensity and not in the direction of the response. Cellular responses induced by dusts collected by different sampling methods did not differ substantially. Unprocessed stable dust samples showed relatively low direct toxicity but were able to trigger immune responses in studied cell model. This suggest that these dust collection methods could be utilized when investigating e.g. asthma-protective mechanisms.

Thermal treatment of municipal solid waste incineration fly ash: Impact of gas atmosphere on the volatility of major, minor, and trace elements.

Development of thermal processes for selective recovery of Zn and other valuable elements from municipal solid waste incineration (MSWI) fly ash requires comprehensive knowledge of the impact of gas atmosphere on the volatile behaviour of the element constituents of the ash at different reaction temperatures. This study assesses the partitioning of 18 elements (Al, As, Bi, C, Ca, Cd, Cl, Cu, K, Mg, Na, P, Pb, S, Sb, Sn, Ti, and Zn) between condensed and gaseous phases during thermal treatment of MSWI fly ash in both oxidising gas and reducing gas atmospheres, at different temperatures spanning the range 200-1050 °C. The operating atmosphere had major impacts on the partitioning of the following elements: As, Bi, C, Cd, Cu, Na, Pb, S, Sb, Sn, and Zn. The partitioning of these elements cannot be accurately predicted over the full range of investigated operating conditions with global thermodynamic equilibrium calculations alone, i.e. without also considering chemical kinetics and mass transfer. In oxidising conditions, the following elements were predominately retained in condensed phases, even at high temperatures: As, Bi, Sb, Sn, and Zn. All these elements, except As, were largely released to the gas phase (>70%) at high temperatures in reducing conditions. The impact of gas atmosphere on the volatility of Cd and Pb was greatest at low reaction temperatures (below ~750 °C). Results for volatile matrix elements, specifically C, Cl, K, Na, and S, are interpreted in terms of the mechanisms governing the release of these elements to the gas phase.

Influence of induction-annealing temperature on the morphology of barley-straw-derived Si@C and SiC@graphite for potential application in Li-ion batteries.

Silicon, a material with high theoretical energy density, holds great promise as a candidate material for anodes in lithium-ion batteries. However, due to an alloying mechanism the material undergoes volume expansion of up to 300%, which results in rapid capacity fading. The coating of silicon with carbon is done by using a biomass-based carbon precursor. The effects of annealing temperature on the morphology of the silicon-carbon structures is presented herein. The mechanically and chemically treated barley straw is mixed with silicon particles and induction annealed in argon atmosphere under different temperatures. The material transformation from carbon-coated silicon (Si@C) to graphite-coated silicon carbide (SiC@graphite) is studied. The Si@C displayed initial specific capacity of 1200 mAh g-1 at 0.1 A g-1, while the capacity retention analysis of Si@C revealed improved cycling stability compared to bare silicon.

Volatilisation of major, minor, and trace elements during thermal processing of fly ashes from waste- and wood-fired power plants in oxidising and reducing gas atmospheres.

This study assesses the volatility of 15 elements (As, Bi, C, Cd, Cl, Cu, K, Mn, Na, P, Pb, S, Sb, Sn, and Zn) during thermal processing of fly ashes obtained from four waste-to-energy plants and one wood-combustion plant. Differences in volatility in oxidising and reducing atmospheres (air and 10% H2/90% N2) were assessed at two temperatures, 700 and 1000 °C. P and Mn were predominately retained in all ashes regardless of the operating atmosphere and temperature. Other elements showed significant variation in volatility depending on the type of fly ash, atmosphere, and temperature. Heat-treatment of the wood-combustion fly ash in the air atmosphere resulted in low release of K, Na, and all investigated heavy metals and metalloids. Several valuable elements, including Zn, Sb, Sn, and Bi, were significantly more volatile in the reducing atmosphere than in the oxidising atmosphere, particularly at 1000 °C. Other elements were either less volatile, equally volatile, or only marginally more volatile when the ashes were heated at 1000 °C in the reducing atmosphere. These elements include C, Cl, Cu, and, in the case of fly ashes derived from municipal solid waste, Cd and Pb. A two-step process, in which municipal solid waste incineration fly ash is first heated in an oxidising atmosphere and then in a reducing atmosphere, is proposed for production of a chloride-free zinc concentrate. Evaluation of the two-step process at 880 °C shows good potential for selective volatilisation of Zn with other valuable elements, including Sn, Sb, and Bi.

A comparative study of magnetic chitosan (Chi@Fe3O4) and graphene oxide modified magnetic chitosan (Chi@Fe3O4GO) nanocomposites for efficient removal of Cr(VI) from water.

Magnetic chitosan (Chi@Fe3O4) nanocomposite was synthesized and modified with graphene oxide (Chi@Fe3O4GO) and the potential of both materials as adsorbents was assessed for the removal of chromium (Cr(VI)) from water. The physico-chemical characteristics of magnetic nanocomposites were studied by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), x-ray diffraction (XRD), Raman spectroscopy and Brunauer-Emmett-Teller (BET). The synthesized adsorbents exhibited varied Cr(VI) removal efficiency at solution pH 2. The reaction kinetics correlated well with the pseudo-second-order model. The maximum adsorption capacity was found to be 142.32 and 100.51 mg g-1 for Chi@Fe3O4 and Chi@Fe3O4GO, respectively. Analysis of thermodynamic parameters suggested that the reaction occurred spontaneously and was endothermic in nature. Reusability studies showed that the adsorbents can be reused for up to four cycles of regeneration. Fixed bed column experiments revealed that the adsorption performance of Chi@Fe3O4 was affected by the flow rate, adsorbent loading and influent metal ion concentration. The results suggest that the prepared adsorbents have the potential to be used in removing Cr(VI) ions from contaminated water.

Spray deposition and characterization of carbon nanoflower and gold-doped carbon nanoflower thin films.

Herein, we present an aerosol filtration method for the fabrication of carbon nanoflower (CNF) thin films. The method was based on generation, evaporation and filtration of solvent encapsulated CNF droplets. The particles were collected on polytetrafluoroethylene membranes and roll-transferred at room temperature onto flexible polyethylene terephthalate substrates. Suspensions for spraying were made in low vapor pressure mixtures of EtOH/Hex (50/50 v/v%). Doping of starter suspensions was made by the addition of organometallic 1-dodecanethiol-coated gold nanoparticles (AuNPs). The produced films displayed substrate surface coverage of up to 83.3% ± 13.9% and a film thickness of up to 2.4 µm. The deposition of doped suspensions resulted in uniform distribution of AuNPs in the volume of the CNF film, which enables film application for flexible photovoltaics.

Is reproducibility inside the bag? Special issue fundamentals and applications of sonochemistry ESS-15.

In this paper we report our most recent attempts to tackle a notorious problem across several scientific activities from the ultrasonics sonochemical perspective: reproducibility of results. We provide experimental results carried out in three different laboratories, using the same ingredients: ultrasound and a novel cavitation reactor bag. The main difference between the experiments is that they are aimed at different applications, KI liberation and MB degradation; and exfoliation of two nanomaterials: graphene and molybdenum disulfide. Iodine liberation rates and methylene blue degradation were higher for the cases where a cavitation intensification bag was used. Similarly, improved dispersion and more polydisperse exfoliated layers of nanomaterials were observed in the intensified bags compared to plain ones. The reproducibility of these new experiments is compared to previous experimental results under similar conditions. Our main conclusion is that despite knowing and understanding most physicochemical phenomena related to the origins and effects of cavitation, there is still a long path towards reproducibility, both in one laboratory, and compared across different laboratories. As emphasized in the sonochemical literature, the latter clearly illustrates the complexity of cavitation as nonlinear phenomenon, whose quantitative estimation represents a challenging aspect. We also provide a list of procedural steps that can help improving reproducibility and scale-up efforts.

Nano-sized zinc oxide and silver, but not titanium dioxide, induce innate and adaptive immunity and antiviral response in differentiated THP-1 cells.

Nano-sized metal oxides are currently the most manufactured nanomaterials (NMs), and are increasingly used in consumer products. Recent exposure data reveal a genuine potential for adverse health outcomes for a vast array of NMs, however the underlying mechanisms are not fully understood. To elucidate size-related molecular effects, differentiated THP-1 cells were exposed to nano-sized materials (n-TiO2, n-ZnO and n-Ag), or their bulk-sized (b-ZnO and b-TiO2) or ionic (i-Ag) counterparts, and genome-wide gene expression changes were studied at low-toxic concentrations (<15% cytotoxicity). TiO2 materials were nontoxic in MTT assay, inducing only minor transcriptional changes. ZnO and Ag elicited dose-dependent cytotoxicity, wherein ionic and particulate effects were synergistic with respect to n-ZnO-induced cytotoxicity. In gene expression analyzes, 6 h and 24 h samples formed two separate hierarchical clusters. N-ZnO and n-Ag shared only 3.1% and 24.6% differentially expressed genes (DEGs) when compared to corresponding control. All particles, except TiO2, activated various metallothioneins. At 6 h, n-Zn, b-Zn and n-Ag induced various immunity related genes associating to pattern recognition (including toll-like receptor), macrophage maturation, inflammatory response (TNF and IL-1beta), chemotaxis (CXCL8) and leucocyte migration (CXCL2-3 and CXCL14). After 24 h exposure, especially n-Ag induced the expression of genes related to virus recognition and type I interferon responses. These results strongly suggest that in addition to ionic effects mediated by metallothioneins, n-Zn and n-Ag induce expression of genes involved in several innate and adaptive immunity associated pathways, which are known to play crucial role in immuno-regulation. This raises the concern of safe use of metal oxide and metal nanoparticle products, and their biological effects.

In vitro toxicological effects of zinc containing nanoparticles with different physico-chemical properties.

Nanomaterials (NM) exhibit novel physicochemical properties that determine their interaction with biological substrates and processes. Recent nano-technological advances are leading to wide usage of metallic nanoparticles (NPs) in various fields. However, the increasing use of NPs has led to their release into environment and the toxicity of NPs on human health has become a concern. Moreover, there are inadvertently generated metallic NPs which are formed during various human activities (e.g. metal processing and energy production). Unfortunately, there are still widespread controversies and ambiguities with respect to the toxic effects and mechanisms of metallic NPs, e.g. metal oxides including ZnO. In this study, we generated zinc containing NMs, and studied them in vitro. Different nano-sized particles containing Zn were compared in in vitro study to elucidate the physicochemical characteristics (e.g. chemical composition, solubility, shape and size of the particles) that determine cellular toxicity. Zn induced toxicity in macrophage cell line (RAW 264.7) was detected, leading to the cell cycle disruption, cell death and excitation of release of inflammatory mediators. The solubility and the size of Zn compounds had a major role in the induced toxic responses. The soluble particles reduced the cell viability, whereas the less soluble NPs significantly increased inflammation. Moreover, uptake of large ZnO NPs inside the cells was likely to play a key role in the detected cell cycle arrest.

Inhalation and Oropharyngeal Aspiration Exposure to Rod-Like Carbon Nanotubes Induce Similar Airway Inflammation and Biological Responses in Mouse Lungs.

Carbon nanotubes (CNTs) have the potential to impact technological and industrial progress, but their production and use may, in some cases, cause serious health problems. Certain rod-shaped multiwalled CNTs (rCNTs) can, in fact, induce severe asbestos-like pathogenicity in mice, including granuloma formation, fibrosis, and even cancer. Evaluating the comparability between alternative hazard assessment methods is needed to ensure fast and reliable evaluation of the potentially adverse effects of these materials. To compare two alternative airway exposure methods, C57BL/6 mice were exposed to rCNTs by a state-of-the-art but laborious and expensive inhalation method (6.2-8.2 mg/m3, 4 h/day for 4 days) or by oropharyngeal aspiration (10 or 40 µg/day for 4 days), which is cheaper and easier to perform. In addition to histological and cytological studies, transcriptome analysis was also carried out on the lung tissue samples. Both inhalation and low-dose (10 µg/day) aspiration exposure to rCNTs promoted strong accumulation of eosinophils in the lungs and recruited also a few neutrophils and lymphocytes. In contrast, the aspiration of a high-dose (40 µg/day) rCNT caused only a mild pulmonary eosinophilia but enhanced accumulation of neutrophils in the airways. Inhalation and low-dose aspiration exposure promoted comparable giant cell formation, mucus production, and IL-13 expression in the lungs. Both exposure methods also exacerbated similar expression alterations with 154 (56.4%) differentially expressed, overlapping genes in microarray analyses. Of all differentially expressed genes, up to 80% of the activated biological functions were shared according to pathway enrichment analyses. Inhalation and low-dose aspiration elicited very similar pulmonary inflammation providing evidence that oropharyngeal aspiration is a valid approach and a convenient alternative to the inhalation exposure for the hazard assessment of nanomaterials.

Reference particles for toxicological studies of wood combustion: formation, characteristics, and toxicity compared to those of real wood combustion particulate mass.

Multiple studies show that particulate mass (PM) generated from incomplete wood combustion may induce adverse health issues in humans. Previous findings have shown that also the PM from efficient wood combustion may induce enhanced production of reactive oxygen species (ROS), inflammation, and cytotoxicity in vitro and in vivo. Underlying factors of these effects may be traced back to volatile inorganic transition metals, especially zinc, which can be enriched in the ultrafine fraction of biomass combustion particulate emission. In this study, nanoparticles composed of potassium, sulfur, and zinc, which are the major components forming inorganic fine PM, were synthesized and tested in vitro. In addition, in vitro toxicity of PM from efficient combustion of wood chips was compared with that of the synthesized particles. Cytotoxicity, cell cycle arrest, ROS generation, and tumor necrosis factor alpha release were related to zinc concentration in PM. Potassium sulfate and potassium carbonate did not induce toxic responses. In light of the provided data, it can be concluded that zinc, enriched in wood combustion emissions, caused the toxicity in all of the measured end points.

Aerosolization behavior of carrier-free L-leucine coated salbutamol sulphate powders.

Aerosolization behavior of carrier-free l-leucine coated salbutamol sulphate inhalable powders has been studied. L-Leucine coatings were formed by physical vapour deposition (PVD) on the surface of the spherical particles in the gas phase. While depositing L-leucine formed pointy crystalline asperities whose size and density increased with the increased content of L-leucine in the gas phase. The asperity size changed from few nanometers to hundreds of nanometers. Due to the rough surface, all these coated fine powders were well-flowable and could be fed without the aid of coarser carriers. The aerosolization characteristics of the powders were studied with 'Inhalation Simulator' under ascending and fast inhalation profiles. When detected on-line by infrared light attenuation, the emission of the coated powders from an inhaler (Easyhaler) was distinctively dependent on the inhalation flow rate less than 30 l/min whereas that of micronized salbutamol sulphate powder solely depended on the studied inhalation flow rate range up to 100 l/min. Gravimetric measurements showed that emitted doses (ED) and fine particle fractions (FPF) of the coated powders were 5.1-7.1 mg/dose and 42-47%, respectively, which were 3-4 times higher than those of the micronized powder. The ED and FPF of the coated powders decreased as the surface roughness increased which is hypothesized as mechanical interlocking between the surface asperities.

Investigations on the humidity-induced transformations of salbutamol sulphate particles coated with L-leucine.

PURPOSE: The crystallization and structural integrity of micron-sized inhalable salbutamol sulphate particles coated with L-leucine by different methods are investigated at different humidities. The influence of the L-leucine coating on the crystallization of salbutamol sulphate beneath the coating layer is explored. METHODS: The coated particles are prepared by an aerosol flow reactor method, the formation of the L-leucine coating being controlled by the saturation conditions of the L-leucine. The coating is formed by solute diffusion within a droplet and/or by vapour deposition of L-leucine. The powders are humidified at 0%, 44%, 65% and 75% of relative humidity and the changes in physical properties of the powders are investigated with dynamic vapour sorption analysis (DVS), a differential scanning calorimeter (DSC), and a scanning electron microscope (SEM). RESULTS: Visual observation show that all the coated particles preserve their structural integrity whereas uncoated salbutamol sulphate particles are unstable at 65% of relative humidity. The coating layer formed by diffusion performs best in terms of its physical stability against moisture and moisture-induced crystallization. The degree of crystallization of salbutamol in the as-prepared powders is within the range 24-35%. The maximum degree of crystallization after drying ranges from 55 to 73% when the salbutamol crystallizes with the aid of moisture. In addition to providing protection against moisture, the L-leucine coating also stabilizes the particle structure against heat at temperatures up to 250 degrees C. CONCLUSION: In order to preserve good flowability together with good physical stability, the best coating would contain two L-leucine layers, the inner layer being formed by diffusion (physical stability) and the outer layer by vapour deposition (flowability).

Simultaneous synthesis and coating of salbutamol sulphate nanoparticles with L-leucine in the gas phase.

Salbutamol sulphate nanoparticles have been simultaneously prepared and coated with L-leucine in the gas phase. Three different ways of coating can be separated based on the operation temperatures used in an aerosol flow reactor. Below the temperature of L-leucine sublimation, formation of the L-leucine layer on the core particle surface takes place via diffusion of L-leucine molecules on the droplet surfaces during droplet drying. At intermediate temperatures, the extent of sublimation of L-leucine depends notably on the concentration, and thus partial evaporation was expected. The L-leucine coating was solely formed via vapor deposition at high reactor temperatures when complete sublimation of L-leucine was obtained. The geometric mean diameter of the core salbutamol particles was approximately 65 nm. In general, particle size increased with the addition of L-leucine. The size distribution remained the same or broadened when the coating layer of the particles was formed via surface diffusion whereas notable narrowing of the distribution was observed when the coating was formed via vapor deposition. Upon desublimation and heterogeneous nucleation on the surfaces of smooth, spherical core particles, L-leucine formed a discontinuous coating with leafy crystals a few nanometers in size.

A novel gas phase method for the combined synthesis and coating of pharmaceutical particles.

PURPOSE: A novel aerosol flow reactor method for the combined gas phase synthesis and coating of particles for drug delivery has been developed. MATERIALS AND METHODS: As an example, micron-sized salbutamol sulfate particles were produced via droplet-to-particle conversion and in-situ coated by the physical vapor deposition (PVD) of L-leucine vapor. RESULTS: During the deposition, L-leucine vapor crystallized on the surfaces of amorphous salbutamol particles. The size of L-leucine crystallites increased with increasing vapor concentration of L-leucine. The salbutamol particles with rough L-leucine surfaces exhibited good flowability enabling to them to be dispersed into air flow without the delivery aid of coarse lactose carriers. CONCLUSIONS: The fraction of particles smaller than 5 micrometers varied between 0.35 and 0.48 when dispersed into 60 l/min air flow having a jet Reynolds number of 30700. When the coated fine particles were blended with lactose carriers, the fine particle fraction was as high as 90%. The L-leucine coating also improved the stability of salbutamol particles when stored at 45% relative humidity atmosphere.