Our purpose was to quantify 36 inorganic chemical elements in aerosols from disposable electronic cigarettes (ECs) and electronic hookahs (EHs), examine the effect of puffing topography on elements ...in aerosols, and identify the source of the elements.
Thirty-six inorganic chemical elements and their concentrations in EC/EH aerosols were determined using inductively coupled plasma optical emission spectroscopy, and their source was identified by analyzing disassembled atomizers using scanning electron microscopy and energy dispersive X-ray spectroscopy.
Of 36 elements screened, 35 were detected in EC/EH aerosols, while only 15 were detected in conventional tobacco smoke. Some elements/metals were present in significantly higher concentrations in EC/EH aerosol than in cigarette smoke. Concentrations of particular elements/metals within EC/EH brands were sometimes variable. Aerosols generated at low and high air-flow rates produced the same pattern of elements, although the total element concentration decreased at the higher air flow rate. The relative amount of elements in the first and last 60 puffs was generally different. Silicon was the dominant element in aerosols from all EC/EH brands and in cigarette smoke. The elements appeared to come from the filament (nickel, chromium), thick wire (copper coated with silver), brass clamp (copper, zinc), solder joints (tin, lead), and wick and sheath (silicon, oxygen, calcium, magnesium, aluminum). Lead was identified in the solder and aerosol of two brands of EHs (up to 0.165 μg/10 puffs).
These data show that EC/EH aerosols contain a mixture of elements, including heavy metals, with concentrations often significantly higher than in conventional cigarette smoke. While the health effects of inhaling mixtures of heated metals is currently not known, these data will be valuable in future risk assessments involving EC/EH elements/metals.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The atomizers of electronic cigarettes (ECs) contain metals that transfer to the aerosol upon heating and may present health hazards. This study analyzed 4th-generation EC pod atomizer design ...features and characterized their elemental/metal composition.
Eleven EC pods from six brands/manufacturers were purchased at local shops and online. Pods were dissected and imaged using a Canon EOS Rebel SL2 camera. Elemental analysis and mapping of atomizer components was done using a scanning electron microscope coupled with an energy dispersive x-ray spectrometer.
EC pods varied in size and design. The internal atomizer components were similar across brands except for variations occurring mainly in the wicks and filaments of some products. The filaments were either Elinvar (nickel, iron, and chromium) (36.4%), nichrome (36.4%), iron-chromium (18.2%), or nickel (9%). Thick wires present in 55% of the atomizers were mainly nickel and were joined to filaments by brazing. Wire-connector joints were Elinvar. Metal air tubes were made of Elinvar (50%), nickel, zinc, copper, and tin (37.5%), and nickel and copper (12.5%). Most of the wick components were silica, except for two pods (PHIX and Mico), which were mainly ceramic. Connectors contained gold-plated nickel, iron-chromium multiple alloys of nickel, zinc, gold, iron, and copper. Wick chambers were made of Elinvar. Outer casings were either nickel, copper-tin, or nickel-copper alloys. Magnets were nickel with minor iron, copper, and sulfur. Some frequently occurring elements were high in relative abundance in atomizer components.
The atomizers of pods are similar to previous generations, with the introduction of ceramic wicks and magnets in the newer generations. The elements in EC atomizers may transfer into aerosols and adversely affect health and accumulate in the environment.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Electronic cigarettes (EC) deliver aerosol by heating fluid containing nicotine. Cartomizer EC combine the fluid chamber and heating element in a single unit. Because EC do not burn tobacco, they may ...be safer than conventional cigarettes. Their use is rapidly increasing worldwide with little prior testing of their aerosol.
We tested the hypothesis that EC aerosol contains metals derived from various components in EC.
Cartomizer contents and aerosols were analyzed using light and electron microscopy, cytotoxicity testing, x-ray microanalysis, particle counting, and inductively coupled plasma optical emission spectrometry.
The filament, a nickel-chromium wire, was coupled to a thicker copper wire coated with silver. The silver coating was sometimes missing. Four tin solder joints attached the wires to each other and coupled the copper/silver wire to the air tube and mouthpiece. All cartomizers had evidence of use before packaging (burn spots on the fibers and electrophoretic movement of fluid in the fibers). Fibers in two cartomizers had green deposits that contained copper. Centrifugation of the fibers produced large pellets containing tin. Tin particles and tin whiskers were identified in cartridge fluid and outer fibers. Cartomizer fluid with tin particles was cytotoxic in assays using human pulmonary fibroblasts. The aerosol contained particles >1 µm comprised of tin, silver, iron, nickel, aluminum, and silicate and nanoparticles (<100 nm) of tin, chromium and nickel. The concentrations of nine of eleven elements in EC aerosol were higher than or equal to the corresponding concentrations in conventional cigarette smoke. Many of the elements identified in EC aerosol are known to cause respiratory distress and disease.
The presence of metal and silicate particles in cartomizer aerosol demonstrates the need for improved quality control in EC design and manufacture and studies on how EC aerosol impacts the health of users and bystanders.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Nature utilizes the available resources to construct lightweight, strong and tough materials under constrained environmental conditions. The impact surface of the fast-striking dactyl club from the ...mantis shrimp is an example of one such composite material; the shrimp has evolved the capability to localize damage and avoid catastrophic failure from high-speed collisions during its feeding activities. Here we report that the dactyl club of mantis shrimps contains an impact-resistant coating composed of densely packed (about 88 per cent by volume) ~65-nm bicontinuous nanoparticles of hydroxyapatite integrated within an organic matrix. These mesocrystalline hydroxyapatite nanoparticles are assembled from small, highly aligned nanocrystals. Under impacts of high strain rates (around 10
s
), particles rotate and translate, whereas the nanocrystalline networks fracture at low-angle grain boundaries, form dislocations and undergo amorphization. The interpenetrating organic network provides additional toughening, as well as substantial damping, with a loss coefficient of around 0.02. An unusual combination of stiffness and damping is therefore achieved, outperforming many engineered materials.
Homogeneously mixing multiple metal elements within a single particle may offer new material property functionalities. High entropy alloys (HEAs), nominally defined as structures containing five or ...more well-mixed metal elements, are being explored at the nanoscale, but the scale-up to enable their industrial application is an extremely challenging problem. Here, we report an aerosol droplet-mediated technique toward scalable synthesis of HEA nanoparticles with atomic-level mixing of immiscible metal elements. An aqueous solution of metal salts is nebulized to generate ∼1 μm aerosol droplets, which when subjected to fast heating/quenching result in decomposition of the precursors and freezing-in of the zero-valent metal atoms. Atomic-level resolution scanning transmission electron microscopy coupled with energy-dispersive X-ray spectroscopy analysis reveals that all metal elements in the nanoparticles are homogeneously mixed at the atomic level. We believe that this approach offers a facile and flexible aerosol droplet-mediated synthesis technique that will ultimately enable bulk processing starting from a particulate HEA.
We report colloidal routes to synthesize silicon@carbon composites for the first time. Surface‐functionalized Si nanoparticles (SiNPs) dissolved in styrene and hexadecane are used as the dispersed ...phase in oil‐in‐water emulsions, from which yolk–shell and dual‐shell hollow SiNPs@C composites are produced via polymerization and subsequent carbonization. As anode materials for Li‐ion batteries, the SiNPs@C composites demonstrate excellent cycling stability and rate performance, which is ascribed to the uniform distribution of SiNPs within the carbon hosts. The Li‐ion anodes composed of 46 wt % of dual‐shell SiNPs@C, 46 wt % of graphite, 5 wt % of acetylene black, and 3 wt % of carboxymethyl cellulose with an areal loading higher than 3 mg cm−2 achieve an overall specific capacity higher than 600 mAh g−1, which is an improvement of more than 100 % compared to the pure graphite anode. These new colloidal routes present a promising general method to produce viable Si–C composites for Li‐ion batteries.
Electrode materials: Two novel routes have been developed to synthesize Si–C composites from colloidal systems. Superior Li‐ion anode performance was achieved, attributed to the uniform dispersal of Si nanoparticles in the secondary carbon structure.
Metals are present in electronic cigarette (EC) fluid and aerosol and may present health risks to users.
The objective of this study was to measure the amounts of tin, copper, zinc, silver, nickel ...and chromium in the aerosol from four brands of EC and to identify the sources of these metals by examining the elemental composition of the atomizer components.
Four brands of popular EC were dissected and the cartomizers were examined microscopically. Elemental composition of cartomizer components was determined using integrated energy dispersive X-ray microanalysis, and the concentrations of the tin, copper, zinc silver, nickel, and chromium in the aerosol were determined for each brand using inductively coupled plasma optical emission spectroscopy.
All filaments were made of nickel and chromium. Thick wires were copper coated with either tin or silver. Wires were joined to each other by tin solder, brazing, or by brass clamps. High concentrations of tin were detected in the aerosol when tin solder joints were friable. Tin coating on copper wires also contributed to tin in the aerosol.
Tin concentrations in EC aerosols varied both within and between brands. Tin in aerosol was reduced by coating the thick wire with silver rather than tin, placing stable tin solder joints outside the atomizing chamber, joining wires with brass clamps or by brazing rather than soldering wires. These data demonstrate the feasibility of removing tin and other unwanted metals from EC aerosol by altering designs and using materials of suitable quality.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
We investigate the detailed effects and mechanisms of sub-nano confinement on lithium-sulfur (Li-S) electrochemical reactions in both ether-based and carbonate-based electrolytes. Our results ...demonstrate a clear correlation between the size of sulfur confinement and the resulting Li-S electrochemical mechanisms. In particular, when sulfur is confined within sub-nano pores, we observe identical lithium-sulfur electrochemical behavior, which is distinctly different from conventional Li-S reactions, in both ether and carbonate electrolytes. Taken together, our results highlight the critical importance of sub-nano confinement effects on controlling solid-state reactions in Li-S electrochemical systems.
Partially reduced TiO2 with highly active facets has been fabricated: Ti3+ was successfully incorporated without any additional reducing agent and surfactant, and highly active facets developed ...preferentially. The product shows improved photocatalytic activity in H2 production over previously reported material. Photocatalytic activity over an extended time period demonstrates the stability of reduced TiO2 made by this approach.
Supercapacitors are promising alternative energy storage systems due to their relatively fast rate of energy storage and delivery. We describe a simple and scalable method to fabricate ...three-dimensional (3D) few-layer graphene/multi-walled carbon nanotube (MWNT) hybrid nanostructures on industrial grade metal foam foils (nickel foam) via a one-step ambient pressure chemical vapor deposition (APCVD) process. The as-grown few-layer graphene/MWNT nanocarbon foams are in the form of a homogeneous and densely packed hierarchical nanostructures and possess a very large surface area of 743m2g−1. Symmetrical electrochemical double-layer capacitors (EDLCs) of 3D hybrid hierarchical few-layer graphene/MWNT nanostructures show a high specific capacitance of 286Fg−1 which leads to an energy density of 39.72Whkg−1 and a superior power density of up to 154.67kWkg−1. Moreover, the capacitance retention of 99.34% after 85000 charge–discharge cycles demonstrates the very high stability of the electrode architectures for supercapacitors. These merits enable the innovative 3D hierarchical few-layer graphene/MWNT foam to serve as high performance EDLC electrodes, resulting in energy storage devices with very high stability and power density.
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► Few-layer graphene/MWNT foam architectures are grown on foamed metal foils. ► The as-grown graphene/MWNT foam architecture possesses a very large surface area. ► Supercapacitors based on this innovative carbon nanostructure foam show superior electrochemical performances. ► Capacitance retention of 99.34% over 85000 charge–discharge cycles demonstrates the very high stability of the novel materials architecture for supercapacitor electrodes.
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