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BackgroundThe 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.MethodsEleven 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.ResultsEC 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.ConclusionsThe 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.

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 104 s-1), 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.

BackgroundSince their release in 2004, electronic cigarettes (ECs) and their atomizers have undergone significant evolution.ObjectiveThe purpose of this study was to evaluate and compare the elemental/metal composition of atomizers in cartomizer and tank style ECs produced over a 5-year period.MethodsPopular cartomizer and tank models of ECs were dissected and photographed using a stereoscopic microscope, and elemental analysis of EC atomizers was done using scanning electron microscopy coupled with energy dispersive x-ray spectroscopy.ResultsEight elements/metals were found in most products across and within brands purchased at different times. These included chromium, nickel, copper, silver, tin, silicon, aluminum, and zinc. Iron and lead were found in some but not all products, while manganese, cobalt, molybdenum, titanium, and tungsten were only found in a few of the products. The metals used in various components were often similar in cartomizer and tank models. Filaments were usually chromium and nickel (nichrome), although in some newer products, the filament also contained iron, copper, and manganese. The thick wire in earlier products was usually copper coated with silver, while in some newer products, the thick wire was predominantly nickel. In all products, the wick was silica, and sheaths, when present, were fiberglass (silicon, oxygen, calcium, aluminum, magnesium). Wire-to-wire joints were either brazed or clamped with brass (copper and zinc), and air-tube-to-thick wire joints, when present, were usually soldered with tin. Tank style products generally lacked a thick wire and sheaths.ConclusionIn general, atomizer components in ECs were remarkably similar over time and between brands. Certain elements/metals were consistently found in most models from all generations, and these should be studied carefully to determine if their transfer to aerosols affects user's health and if their accumulation in trash affects the environment.

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.

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.

An understanding of the thermodynamics of triple-chain silicate phases can offer insight into their formation in nature. Because the more common Mg triple-chain silicates have not yet been synthesized, this study focused on the Na-analogue to clinojimthompsonite (Na-cjt), which forms readily in a laboratory setting. Synthetic Na-cjt was characterized using electron microscopy and microanalysis, thermogravimetric analysis, infrared spectroscopy, and loss on ignition to determine its water content. The results of these studies indicated a formula for Na-cjt of [Na.sub.3.74][Mg.sub.8.13][Si.sub.12][O.sub.32.00][(OH).sub.4]*1.40 [H.sub.2]O, although there was substantial uncertainty ([+ or -] 13%) associated with the total water (OH + [H.sub.2]O) content. A series of experimental reversals was performed over a temperature range of 350-650[degrees]C and a pressure range of 0.1-1 GPa for the reaction between Na-cjt and a double-chain silicate. In the pressure range of 0.2-0.5 GPa, this reaction has the stoichiometry [Na.sub.3.74] [Mg.sub.8.13][Si.sub.12][O.sub.32.00][(OH).sub.4]*1.40[H.sub.2]O(Na-cjt) = 1.5 [Na.sub.2.49][Mg.sub.5.42][Si.sub.8][O.sub.21.34][(OH).sub.2.66] (Na-Mg amph) + 1.40 [H.sub.2]O. The equilibrium boundary reaches a maximum temperature near 550[degrees]C at 0.4 GPa, continuing to lower temperatures above this pressure. The third-law entropy and enthalpy of formation of both Na-cjt and the associated Na-Mg amphibole were measured using adiabatic and oxide-melt solution calorimetry, respectively. Calculating the equilibrium boundary for the reaction using the calorimetrically determined values does not produce the same boundary found through the experimental reversals. The discrepancy was attributed to water variability in Na-cjt with pressure. This variability and its effect on Na-cjt's thermodynamic values can be expressed by the following equations that, for simplicity, indicate the total water content (OH + [H.sub.2]O) as moles of [H.sub.2]O in Na-cjt over the range of 0.1 to 1.0 GPa: [MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII.] where the entropy does not include any contributions from configurational mixing. If one includes configurational entropy contributions from cation and vacancy disorder in the triple-chain silicate and amphibole, one obtains [S.sup.o] and [DELTA][H.sup.o.sub.f] for Na-cjt of 919.2 J/(K*mol) and-18417.6 kJ/mol, respectively, and [S.sup.o] and [DELTA][H.sup.o.sub.f] for Na-Mg amphibole of 650.9 J/(K*mol) and -11 919.7 kJ/mol, respectively. Keywords: Triple-chain silicate, Na-clinojimthompsonite, thermochemistry, calorimetry

A series of experiments with and without sample retreatment was performed on a starting mixture of dolomite plus quartz at 0.5 GPa and 600 [degrees]C in a C[O.sub.2]-[H.sub.2]O fluid with a mole fraction of C[O.sub.2] of 0.2 for durations up to 582 h. The initial reaction of dolomite and quartz led to rapid formation of talc and calcite instead of tremolite and calcite by the intended reaction: 5 dolomite + 8 quartz + [H.sub.2]O = tremolite + 3 calcite + 7 C[O.sub.2]. With continued treatment, the talc+ calcite + quartz assemblage gradually reacts to form increasing amounts of tremolite and diopside with the eventual loss of quartz and nearly complete loss of talc. The detailed structure of the amphibole and the nature of the Mg enrichment were revealed using AEM analysis of individual amphibole crystals. The most abundant defects are triple-chain chain multiplicity faults (CMFs), which appear as isolated lamellae with single periodicity in short-duration experiments and increasingly as groups of lamellae with variable multiplicity and periodicity in longer duration experiments and especially in a long-duration experiment without retreatment. In this latter experiment, a calcian clinojimthompsonite domain extending 15 unit cells along the b axis was observed. The sample after 582 h and five retreatments shows, on average, 3.5% true solid solution with Mg expressed as the Mg-cummingtonite (MC) component after correction for the presence of CMFs. This sample is thought to most closely approach the equilibrium composition for the amphibole. The sample after 250 h with three retreatments has about 10%, whereas that after 582 h without retreatment has 0.6% MC component, the latter having a relatively high density of CMFs. This study affirms the importante that precursor non-amphibole biopyriboles play in the formation of tremolitic amphibole. Keywords: Tremolite, HRTEM, analytical electron microscopy, mineral growth, calcian clinojimthompsonite

The room temperature synthesis approach helps in studying the transformation of the amorphous zeolite A precursors with minimum invasive postsynthesis treatments. The void structures in the solid part of the system and their solid-liquid interfaces are identified as the specific locations where the formation of protozeolite nuclei takes place.

A series of low-Ca (1.8-1.65 atoms Ca per formula unit) actinolites were synthesized in the system CaO-FeO-MgO-Si[O.sub.2]-[H.sub.2]O with bulk compositions of 0, 10, 20, and 30 mol% ferro-actinolite when projected onto the tremolite--ferro-actinolite join for the purpose of determining the cation site occupancies as a function of bulk composition. Syntheses were done by multiple treatments of the oxide-metal mixtures in internally heated gas vessels at 600-800 [degrees]C, 6 kbar, f[o.sub.2] near the Co-CoO buffer, which is sufficiently low to prevent the appearance of [Fe.sup.3+] in this study, and for total durations up to 774 hours. Bulk compositions of the synthesis products were assessed by electron microprobe analysis (EMPA), analytical transmission electron microscopy (AEM), and by using unit-cell dimensions (CD method), whereas the site occupancies were assessed using powder X-ray diffraction (XRD) Rietveld refinements, Fourier-transform infrared (FTIR) spectroscopy, and Mossbauer spectroscopy. Selected-area electron-diffraction (SAED) patterns and high-resolution transmission electron microscopy (HRTEM) images were obtained to study the stRucture and defects of the samples. A maximum of about 2% non-amphibole chain-multiplicity faults (CMFs) were observed in the sample with 10 mol% ferroactinolite component, indicating the strong reduction in CMFs that occurs with only a small addition of ferro-actinolite to tremolitic amphiboles. This study, as with earlier studies, found no significant preferential partitioning of Fe and Mg relative to the bulk Fe content of the sample at the M1 and M3 sites, weak partitioning of Mg relative to Fe into the [M.sub.2] site, and strong partitioning of Fe relative to Mg at the M4 site. No ferric iron was detected. The partitioning of Fe and Mg at the M4 site was modeled by a simple ideal-activity, two-site exchange reaction using the actinolites from this study and those of previous studies with bulk Fe/(Fe + Mg) [less than or equal to] 0.3 and with low Al, Mn, and Na contents using 1 bar and 298K values of [DELTA]G[degrees] = 62 kJ and [DELTA]S[degrees] = 54 J/K. The FFIR data were analyzed for the presence of short-range order of Fe and Mg at the M1 and M3 sites but none was found.

FAU-type zeolite was synthesized at room temperature to study the mechanism of its formation. The processes taking place at the nanometer scale were studied by transmission electron microscopy (TEM) and the crystalline character of the particles observed during the induction period was determined by in situ synchrotron XRD analysis.

The first direct transmission electron microscopic (TEM) observation is carried out on the continuous monocrystal-thick b-oriented pure silica zeolite MFI films produced by in situ crystallization. This TEM investigation provides direct unambiguous new evidence to support the homogeneous nucleation mechanism by which the films form through homogeneous nucleation and crystal growth in the bulk to form equal-sized disk-shape crystals followed by self-assembly of these crystals onto the substrate to produce a two-dimensional close-packed structure.

The formation mechanisms of tremolite in a time series of hydrothermal experiments at 850 [degrees]C and 6.l kbar were studied using transmission electron microscopy (TEM), analytical TEM, and X-ray diffraction. The starting materials were unseeded mixtures of reagent-grade oxides. After the first 8 min of reaction, the synthesis products were diopside, enstatite, clinoenstatite, quartz, and minor C-centered and primitive monoclinic amphibole (13 wt% total). The compositions of the first-formed amphiboles vary considerably, from essentially pure cummingtonite (Ca/Mg = 0) to nearly ideal tremolite (Ca/Mg = 0.4). Three groupings of amphiboles with successively higher Ca/Mg ratios were identified, respectively 0.1. 0.22. and 0.35. Over a period of 97 h, the proportions of Mg-rich amphibole gradually decrease, and the average Ca/Mg ratios of all amphiboles steadily increase from about 0.22 to 0.35. Other changes include: (1) a decrease in the aspect ratio of amphibole crystals with increasing time: (2) a decrease in the number of non-amphibole chain multiplicity faults (CMFs), from early A'(2) values as low as 0.81 to a final value of 0.94; and (3) a distinct change in the rate of amphibole growth after l h of synthesis. These observations suggest that two mechanisms of amphibole formation are dominant: (1) formation of pyroxene modules with subsequent hydration and arrangement into the double-chain amphibole structure and (2) direct nucleation and growth of amphibole from hydrothermal solution. A third mechanism involving formation of talc-like modules, followed by their breakdown into double-chain modules, incorporation of Ca, and ordering into the amphibole structure, may also occur but probably only at the lamellar or unit-cell scale, because these syntheses were performed outside the stability field of talc.

The re-investigation of the synthesis, characterization, and upper-thermal stability of ferro-actinolite is performed in the system CaO-FeO-SiO2-H2O. The results obtained from the different experiments conducted on ferro-actinolites are given.

High-resolution transmission-electron microscopy (HRTEM) and infrared spectroscopy (FTIR) analyses have been done on amphiboles near the join tremolite [[Ca.sub.2][Mg.sub.5][Si.sub.8][O.sub.22][(OH).sub.]2 = TR]-pargasite [Na[Ca.sub.2][Mg.sub.4][Al.sub.3][Si.sub.6][O.sub.22] [(OH).sub.2] = PG] in the ternary system tremolite-pargasite-cummingtonite [[Mg.sub.7][Si.sub.][O.sub.22] [(OH).sub.2] = MC] that were synthesized previously by Sharma and Jenkins (1999). Representative samples across the join were examined in detail by HRTEM to document the presence and concentration of chain multiplicity defects (CMFs). There was relatively little change in the defect density with composition, with the tremolitic sample (TREM 23-13) having the highest defect concentration (6%) and the more PG-rich samples having slightly lower CMF concentrations (4-5%). CMFs with multiplicities of 1,3, 4, 5, and 6 were observed, usually as isolated chains, with the most common being triple-chain slabs. Correction of the bulk composition of the tremolitic amphibole for the presence of these Mg-rich, wide-chain defects reduces the MC content from an apparent value of 8.5 to 4-7.5 mol% MC, depending on which composition is used for the triple-chain defect. The entire amphibole join was examined by FTIR spectroscopy in the OH-stretching region (3000-3800 [cm.sup.-1]) for the purpose of determining the presence of short-range order. A total of 10 component bands were fitted to the spectra across the join. These bands were assigned to specific cation configurations on the basis of earlier studies of the FTIR spectra of chemically simplified amphibole joins pertinent to this study. The extent of short-range order was qualitatively determined by comparing the observed intensities for groups of related bands, corrected for differences in their molar absorptivities, to their calculated intensifies based on random-mixing probabilities. From this exercise, it is observed that the intensities of sodic amphibole configurations are consistently high, tremolite is lowest near the middle of the join, and aluminous amphibole configurations cross over from being higher (at low A1 contents) to being lower (at high A1 contents) than expected near the middle of the join. These differences between observed and predicted band intensities may reflect the presence of deviations in the thermodynamic activities of amphibole components from those predicted on the basis of random-mixing models.

A critical aspect of the debate about the origin and conditions of metamorphism of the Alpe Arami (AA) peridotite is the disagreement over how much ilmenite is contained in the older generation of olivine and therefore how much Ti[O.sub.2] might have been dissolved at high pressure and temperature. We have now determined quantitatively the 3-dimensional distribution of ilmenite in AA olivine by confocal laser scanning microscopy (CLSM). The CLSM measurements show an average concentration of 0.31 vol% of ilmenite in olivine, with individual grains containing up to 1.2 vol%. This translates into average and maximum concentrations of 0.23 and 0.9 wt% Ti[O.sub.2] in olivine, respectively, and confirms the original estimation of maximum concentration of ~1 vol% Ti[O.sub.2]. The vast majority of ilmenite in AA olivine is distributed randomly (although topotactically oriented) and, in all cases, is accompanied by chromite in a ratio of ~4:1. These observations are consistent with an origin of the ilmenite (and chromite) by exsolution from an olivine solid solution at P = 9-12 GPa and temperatures above the stability field of titanian clinohumite, but are not consistent with suggested breakdown of titanian clinohumite. Combining these results with other recent findings suggests that exsolution followed deformation under relatively high fugacity of [H.sub.2]O, and that the high solubility of Ti[O.sub.2] is probably explained by pressure-induced accommodation of Ti in the tetrahedral site of silicates.

The mesopores formation in zeolite crystals has long been considered to occur through the stochastic hydrolysis and removal of framework atoms. Here, we investigate the NH4F etching of representative small, medium, and large pore zeolites and show that the zeolite dissolution behavior, therefore the mesopore formation probability, is dominated by zeolite architecture at both nano‐ and sub‐nano scales. At the nano‐scale, the hidden mosaics of zeolite structure predetermine the spatio‐temporal dissolution of the framework, hence the size, shape, location, and orientation of the mesopores. At the sub‐nano scale, the intrinsic micropore size and connectivity jointly determine the diffusivity of reactant and dissolved products. As a result, the dissolution propensity varies from removing small framework fragments to consuming nanodomains and up to full digestion of the outmost part of zeolite crystals. The new knowledge will lead to new understanding of zeolite dissolution behavior and new adapted strategies for tailoring hierarchical zeolites. [ABSTRACT FROM AUTHOR]

The changes in composition and structure of sodium hydroxide rich aluminosilicate gel yielding zeolite A are studied. The studies have shown the unrivaled sensitivity of hyperpolarized (HP) [super 129]Xe NMR that is capable of identifying presence of small amounts of crystalline zeolite material in amorphous medium with detection limit extending below 1 wt%.