NaCl Layer Research Articles

Detection of carotenoids of halophilic prokaryotes in solid inclusions inside laboratory-grown chloride and sulfate crystals using a portable Raman spectrometer: applications for Mars exploration.

Inclusions in evaporitic minerals sometimes contain remnants of microorganisms or biomarkers, which can be considered as traces of life. Raman spectroscopy with resonance enhancement is one of the best analytical methods to search for such biomarkers in places of interest for astrobiology, including the surface and near subsurface of planet Mars. Portable Raman spectrometers are used as training tools for detection of biomarkers. Investigations of the limits and challenges of detecting biomolecules in crystals using Raman spectroscopy is important because natural occurrences often involve mineral assemblages as well as their fluid and solid inclusions. A portable Raman spectrometer with 532nm excitation was used for detection of carotenoid biomarkers: salinixanthin of Salinibacter ruber (Bacteroidetes) and α-bacterioruberin of Halorubrum sodomense (Halobacteria) in laboratory-grown artificial inclusions in compound crystals of several chlorides and sulfates, simulating entrapment of microorganisms in evaporitic minerals. Crystals of halite (NaCl), sylvite (KCl), arcanite (K2SO4) and tschermigite ((NH4)Al(SO4)2·12H2O) were grown from synthetic solutions that contained microorganisms. A second crystalline layer of NaCl or K2SO4 was grown subsequently so that primary crystals containing microorganisms are considered as solid inclusions. A portable Raman spectrometer with resonance enabling excitation detected signals of both carotenoid pigments. Correct positions of diagnostic Raman bands corresponding to the specific carotenoids were recorded.

Effect of streaming water vapor on the corrosion behavior of Ti60 alloy under a solid NaCl deposit in water vapor at 600 °C

The corrosion behavior of Ti60 alloy coated with solid NaCl layer in dry O2 and humid O2 (30.8 vol.% H2O) environments at 600 °C have been investigated. The isotopic tracing of 18O showed involvement of H2O in both the outer corrosion layer (OCL) and the inner corrosion layer (ICL). Theoretical calculations revealed that H2O provided 14% and 21% of the oxygen required for the formation of the outer and inner corrosion layers, respectively. Detailed analysis of corrosion products revealed that H2O enhanced the reaction of solid NaCl and TiO2 to form Na4Ti5O12 and promoted the crystallinity of corrosion products.

Dual Oxygen Defects in Layered La1.2Sr0.8-xBaxInO4+δ (x = 0.2, 0.3) Oxide-Ion Conductors: A Neutron Diffraction Study.

The title compounds exhibit a K2NiF4-type layered perovskite structure; they are based on the La1.2Sr0.8InO4+δ oxide, which was found to exhibit excellent features as fast oxide-ion conductor via an interstitial oxygen mechanism. These new Ba-containing materials were designed to present a more open framework to enhance oxygen conduction. The citrate-nitrate soft-chemistry technique was used to synthesize such structural perovskite-type materials, followed by annealing in air at moderate temperatures (1150 °C). The subtleties of their crystal structures were investigated from neutron powder diffraction (NPD) data. They crystallize in the orthorhombic Pbca space group. Interstitial O3 oxygen atoms were identified by difference Fourier maps in the NaCl layer of the K2NiF4 structure. At variance with the parent compound, conspicuous oxygen vacancies were found at the O2-type oxygen atoms for x = 0.2, corresponding to the axial positions of the InO6 octahedra. The short O2–O3 distances and the absence of steric impediments suggest a dual oxygen-interstitial mechanism for oxide-ion conduction in these materials. Conductivity measurements show that the activation energy values are comparable to those typical of ionic conductors working by simple vacancy mechanisms (~1 eV). The increment of the total conductivity for x = 0.2 can be due to the mixed mechanism driving both oxygen vacancies and interstitials, which is original for these potential electrolytes for solid-oxide fuel cells.

Experimental method for observing the fate of SO3/H2SO4 in a temperature-decreasing flue gas flow: Creation of state diagram

The condensation behavior of sulfur trioxide/sulfuric acid (SO3/H2SO4) in flue gas is closely related to corrosion, aerosol formation, and blue plume discharge. Thus, it has become a hot issue in energy and environmental fields. However, no accurate method is currently available to observe this condensation behavior. In this work, an experimental method was developed to explore the fate of SO3/H2SO4 in a temperature-decreasing flue gas flow among the range of 260 °C–40 °C. A novel sampling unit with quartz wool and sodium chloride (NaCl) layer in series was adopted to accomplish the task of collecting aerosol and gaseous H2SO4, respectively, from flue gas. Bench scale experiments were performed to verify the reliability of the method. A state diagram was created according to the experimental results to reveal the fate evolution of H2SO4 as the flue gas temperature dropped. On the basis of the state diagram, the existing empirical models for predicting acid dew point (ADP) were evaluated. The predicted ADP values were found to deviate from the definition, falling within the temperature range in which H2SO4 condensed rapidly instead of the point in which H2SO4 was beginning to condense. The state diagram derived in this work can reveal slight acid condensation behavior better than other methods could.

Evaluation of calculus imaging on root surfaces by spectral-domain optical coherence tomography.

The aim of this in vitro study was to evaluate the ability of optical coherence tomography (OCT) to display calculus on root surfaces. Ten teeth with calculus on the root surface were embedded in resin, omitting the root surface. A region of interest (ROI) was marked by small drill holes coronally and apically of the calculus and imaged by spectral-domain optical coherence tomography ([SD OCT], Telesto SP5, centre wavelength 1310 nm) and light microscopy (LM). To evaluate the impact of different fluids on calculus visualisation, using OCT, root surfaces were covered by a layer of NaCl and blood and displayed by OCT. Subsequently, teeth were completely covered with resin and sectioned for histological evaluation. Within the ROI, lengths of root surface and calculus were measured by LM and OCT, and the ratio [%] was calculated. In addition, at three sites of each ROI, agreement of presence and length of calculus was evaluated. Both methods were compared using Pearson's correlation. Regarding the presence of calculus, agreement between LM and OCT was strong (κi = 0.783, p = 0.033), and measurements regarding the length of the calculus were strongly correlated (ri >0.906; pi <0.001). However, the values differed for dry (p = 0.023) and NaCl-covered root surfaces (p = 0.035). Calculus on the root surface can be displayed by SD-OCT, which therefore may be suited as imaging technology for subgingival calculus in periodontal pockets.

Multilayered surface for the interactive separation of perchlorate from aqueous medium

Environmental contextPerchlorate from rocket fuel plants or firework manufacturing units can seriously contaminate drinking water. We developed a separation skin on a microfiltration membrane and on sand that can remove perchlorate from water in the presence of competing ions. This method is suitable for a domestic water purification unit selective for perchlorate removal. AbstractThis study reports an interactive separation of perchlorate (ClO4−) by polyethyleneimine (PEI) and poly (styrene sulfonate) (PSS) deposited on a microfiltration membrane and on sand surfaces. The variation of the interaction with respect to deposition and feed variables was assessed. The 9 bilayered ((PEI/PSS) 0.15M NaCl, pH 6)) membranes showed a ClO4− rejection of ~80%. An increase in the feed concentration to 25mgL−1 reduced the rejection to 58%. With a feed pH from 4 to 10, the rejection varied between almost 100% and 16%. The presence of ions reduced the rejection percentage of ClO4− with the interference by the ions in the order of SO42−&amp;gt;HCO3−&amp;gt;NO3−&amp;gt;Cl−. The interference is attributed to the characteristics of the competing ions and the nature of the multilayers. A positive impact of post-treatment (98%) and capping layers on rejection percentage (80% to nearly complete) for synthetic and ClO4− contaminated field water samples is clearly established. The presence of competing ions is also accounted for by a capped membrane system. The selectivity of the competing ions increases with capping layers of 1M NaCl in the order of HCO3−&amp;gt;NO3−&amp;gt;SO42−. In the field water samples up to a SO42− concentration of 3.0mgL−1, the capping layers with 0.4M NaCl result in a near complete rejection of ClO4−, whereas further enhancement requires a capping layer of 1M NaCl. A sand filtration system was developed by incorporating the pre-optimised polyelectrolyte multilayer on sand. Deposition of a single bilayered PEI/PSS multilayer on sand effectively (nearly completely) removes ClO4−.

Ultra-thin NaCl films as protective layers for graphene.

The ageing of graphene is an important issue that limits its technological applications. Capping layers are a good option for circumventing this problem. In this work, we propose the use of ultra-thin NaCl films as easily-removable protective layers. We have carried out a detailed characterization of the NaCl/graphene interface on metal substrates, namely Cu(111) and Ir(111), by means of complementary microscopy, electron diffraction and spectroscopic techniques. Interestingly, we show that NaCl neither interacts in a chemical way with graphene nor intercalates through it. We demonstrate that the NaCl film is stable under ambient conditions, protecting the graphene surface from oxidation. In addition, after removing the protective layer, graphene remains intact.

Experiment study of the effect of salt on the stability of solar ponds

The sun is the largest source of renewable energy and this energy is abundantly available in all part of the earth. One way to trap solar energy is through the use of salt‐gradient solar ponds (SGSP). Collecting and storing of energy for this device is in one system, so the heat in summer can be utilized in winter. A typical SGSP consists of a pond containing three density stratified layers. The stability duration and the efficiency of a SGSP depend closely on the self‐maintenance of the NCZ layer, which itself depends on the type of the used salt. This article reviews nonconvective solar ponds, the problems encountered in their operations and the effect of the used salts. Three salts: NaCl, MgCl, and CaCl2 were tested in a laboratory set‐up under different operating conditions. Temperature and concentration gradients were developed by heating the pond from the bottom. The results showed that MgCl and CaCl2 stratification remains stable until the temperature reaches around 70 °C while NaCl layers were mixed at 55 °C. © 2018 American Institute of Chemical Engineers Environ Prog, 38: 699–705, 2019

Mapping the Conductance of Electronically Decoupled Graphene Nanoribbons.

With the advent of atomically precise synthesis and consequent precise tailoring of their electronic properties, graphene nanoribbons (GNRs) have emerged as promising building blocks for nanoelectronics. Before being applied as such, it is imperative that their charge transport properties are investigated. Recently, formation of a molecular junction through the controlled attachment of nanoribbons to the probe of a scanning tunneling microscope (STM) and subsequent lifting allowed for the first conductance measurements. Drawbacks are the perturbation of the intrinsic electronic properties through interaction with the metal surface, as well as the risk of current-induced defect formation which largely restricts the measurements to low bias voltages. Here, we show that resonant transport-essential for device applications-can be measured by lifting electronically decoupled GNRs from an ultrathin layer of NaCl. By varying the applied voltage and tip-sample distance, we can probe resonant transport through frontier orbitals and its dependence on junction length. This technique is used for two distinct types of GNRs: the 7 atom wide armchair GNR and the 3,1-chiral GNR. The features in the conductance maps can be understood and modeled in terms of the intrinsic electronic properties of the ribbons as well as capacitive coupling to tip and substrate. We demonstrate that we can simultaneously measure the current decay with increasing junction length and bias voltage by using a double modulation spectroscopy technique. The strategy described in this work is widely applicable and will lead to a better understanding of electronic transport through molecular junctions in general.

Complexity at simple interfaces: Dynamically generated deep trap states at the noble-metal/alkali-halide interface

The trapping of delocalized electrons at ultrathin layers of NaCl on Ag(100) is investigated in real time using two-photon photoemission. Above 79 K, electrons localize to deep trap states assigned to low-coordinated sites on the NaCl surface. Below 79 K, these low-coordinated trap states serve as precursors for a new deep trap state at increased binding energies. The observation that the emerging trap state requires a localized precursor state suggests that a dynamic polarization of the NaCl lattice may be required for its formation. This behavior is consistent with the expectations for the formation of a interfacial (electron) small polaron which is theoretically unstable in bulk NaCl. The alkali-halide/noble-metal interface shows the sequential population of multiple metastable deep trap states in two dimensions in real time.

Innovative methodology based on the thermo-denuder principle for the detection of combustion-related solid particles or high boiling point droplets: Application to 3R4F cigarette and the Tobacco Heating System THS 2.2

Combustion-related solid particles are known to potentially have adverse effects on human health. In order to enhance further our understanding of how such particles trigger biological responses in humans, it is crucial to ensure that these particles are specifically collected, and are subsequently properly characterized. To separate the solid particles from an aerosol which contain also gases and liquid droplets, a methodology using a Dekati thermo-denuder operated at 300 °C was established. The current work addresses the performance of the method by assessing its average removal efficiency based on pre-determined aerosol average penetration values for model solid particles and liquid droplets. The solid particle average penetration, or the so-called transmission efficiency, was measured to be 79.4 ± 7.3% based on the aerosol wall losses. Although penetration is size-dependent, in the current work it was assumed that poly-disperse dry NaCl particles were a good surrogate to evaluate the equipment average wall losses of combustion-related fine solid particles. To assess the ability of the thermo-denuder to remove liquid droplets from aerosols, aqueous solutions of propylene glycol and glycerin were nebulized. The largest penetration value was measured to be 2.7 ± 1.0%. As a result, the methodology limit of detection was calculated to be 3.7% and the lower limit of quantification (LLOQ) 11.1%. Moreover, further experiments were conducted to ensure that liquid-coated solid particles could be distinguished from non-evaporated droplets to avoid data misinterpretation. To this end, ∼ 70 nm-NaCl particles were coated with glycerin reaching a size diameter of the order of a micron. The experiments showed that the layer of glycerin-coated NaCl was removed entirely when the aerosol passed through the thermo-denuder for the submicron size range. As an application of the methodology, the 3R4F reference cigarette mainstream smoke and Tobacco Heating System 2.2 (THS 2.2) mainstream aerosol were tested in the thermo-denuder. The data demonstrated that for 3R4F mainstream smoke, solid particles or high boiling point droplets were quantified far above the LLOQ. In contrast, for THS 2.2 mainstream aerosol, the penetration overlapped the LLOQ within the range of experimental uncertainty. In the current work, no combustion-related particles were detected or observed when using THS2.2, and this confirms former data published on this subject.

Performance analysis of surface plasmon resonance sensor with high-order absentee layer**Project supported by the National Natural Science Foundation of China (Grant Nos. 11547183 and 11547241), the Higher Education and High-quality and World-class Universities, China (Grant No. PY201612), the National Key Research and Development Program of China (Grant No. 2016YFB0302003), and the Natural Science Foundation of Beijing (Grant No. 2162033).

A surface plasmon resonance (SPR) sensor with a high-order absentee layer on the top of metallic film is proposed. The performance of the SPR sensor with NaCl, MgO, TiO2 or AlAs high-order absentee layer is analyzed theoretically. The results indicate that the sensitivity and the full width at half maximum of those SPR sensors decrease with the increasing of the order of absentee layer, but the variation of the figure of merit (FOM) depends on the refractive index of absentee layer. By improving the order of absentee layer with high-refractive-index, the FOM of the SPR sensor can be enhanced. The maximum value of FOM for the SPR sensor with high-order TiO2 (or AlAs) absentee layer is 1.059% (or 2.587%) higher than the one with one-order absentee layer. It is believed the proposed SPR sensor with high-order absentee layer will be helpful for developing the high-performance SPR sensors.

Combining light-harvesting with detachability in high-efficiency thin-film silicon solar cells.

Efforts to realize thin-film solar cells on unconventional substrates face several obstacles in achieving good energy-conversion efficiency and integrating light-management into the solar cell design. In this report a technique to circumvent these obstacles is presented: transferability and an efficient light-harvesting scheme are combined for thin-film silicon solar cells by the incorporation of a NaCl layer. Amorphous silicon solar cells in p-i-n configuration are fabricated on reusable glass substrates coated with an interlayer of NaCl. Subsequently, the solar cells are detached from the substrate by dissolution of the sacrificial NaCl layer in water and then transferred onto a plastic sheet, with a resultant post-transfer efficiency of 9%. The light-trapping effect of the surface nanotextures originating from the NaCl layer on the overlying solar cell is studied theoretically and experimentally. The enhanced light absorption in the solar cells on NaCl-coated substrates leads to significant improvement in the photocurrent and energy-conversion efficiency in solar cells with both 350 and 100 nm thick absorber layers, compared to flat-substrate solar cells. Efficient transferable thin-film solar cells hold a vast potential for widespread deployment of off-grid photovoltaics and cost reduction.

Image potential states mediated STM imaging of cobalt phthalocyanine on NaCl/Cu(100)**Project supported by the National Natural Science Foundation of China (Grant Nos. 21203239 and 21311120059) and RFBR (Grant No. 13-02-91180).

The adsorption and electronic properties of isolated cobalt phthalocyanine (CoPc) molecule on an ultrathin layer of NaCl have been investigated. High-resolution STM images give a detailed picture of the lowest unoccupied molecular orbital (LUMO) of an isolated CoPc. It is shown that the NaCl ultrathin layer efficiently decouples the interaction of the molecules from the underneath metal substrate, which makes it an ideal substrate for studying the properties of single molecules. Moreover, strong dependence of the appearance of the molecules on the sample bias in the region of relatively high bias (> 3.1 V) is ascribed to the image potential states (IPSs) of NaCl/Cu(100), which may provide us with a possible method to fabricate quantum storage devices.

Introduction of interstitial oxygen atoms in the layered perovskite LaSrIn1 − xBxO4 + δ system (B=Zr, Ti)

K2NiF4-type perovskite oxides LaSrIn1−xBxO4+δ (B=Zr, Ti) were synthesized and characterized in order to identify its capability of incorporating interstitial oxygen atoms (δ) and their effect on the crystal structure and oxide-ion conduction. The synthesis has been performed by a citrate-nitrate soft-chemistry technique followed by annealings in air at moderate temperatures (1000°C). The samples have been characterized at room temperature from x-ray diffraction (XRD) and the structure has been analyzed from neutron powder diffraction (NPD) data in the Pbca space group. Interstitial oxygen atoms were identified by difference Fourier maps in the NaCl layer of the K2NiF4 structure; subsequent Rietveld refinements yield excess oxygen values, δ=0.048(4) and 0.079(5) for B=Zr with x=0.1 and 0.2, respectively, and δ=0.049(5) for B=Ti, x=0.1. The performance of each oxide as a potential oxide ion conductor was evaluated by ac impedance spectroscopy using Pt as electrodes and compared with the parent compound LaSrInO4. The lowest activation energy and better ion conductivity were observed for LaSrIn0.8Zr0.2O4+0.08, which is consistent with the highest amount of interstitial oxygen found from NPD data.

Effect of dynamic diffusion of air, nitrogen, and helium gaseous media on the microhardness of ionic crystals with juvenile surfaces

The load dependences of the microhardness of surface layers of NaCl and LiF ionic single crystals with juvenile surfaces and surfaces exposed to air for a long time measured in the air, nitrogen, and helium gaseous media have been investigated. It has been found that there is a change in the sign of the derivative of the microhardness as a function of the load for LiF crystals indented in helium and after their aging in air, as well as a weaker effect of the nitrogen and air gaseous media on the studied dependences as compared to NaCl crystals. It has also been found that, after the aging of the surface of NaCl crystals in air, there is a change in the sign of the derivative of the microhardness in the nitrogen and air gaseous media, as well as a pronounced change in the microhardness as a function of the time of aging the samples in air as compared to the weaker effect of the gaseous medium for LiF crystals. The obtained data have been analyzed in terms of the phenomenon of dislocation-dynamic diffusion of particles from the external medium into crystalline materials during their plastic deformation along the nucleating and moving dislocations. It has been shown that this phenomenon affects the microhardness through changes in the intensity of dislocation multiplication upon the formation of indentation rosettes in different gaseous media. The performed investigation of the microhardness of the juvenile surface of NaCl and LiF crystals in different gaseous media has revealed for the first time a different character of dislocation-dynamic diffusion of these media in a “pure” form.

NaCl][Cu(HSeO3)2], NaCl-intercalated Cu(HSeO3)2: synthesis, crystal structure and comparison with related compounds

Abstract Single crystals of [NaCl][Cu(HSeO3)2] have been prepared by the chemical vapor transport reactions. Its crystal structure (monoclinic, C2/c, a = 13.9874(7), b = 7.2594(4), c = 9.0421(5) Å, β = 127.046(2)°, V = 732.81(7) Å3) is based upon electroneutral [Cu(HSeO3)2] sheets formed by corner sharing between the [CuO4] squares and (HSeO3) groups that are parallel to the (100) plane. Each (SeO2OH)– group forms the Oh1...O2 hydrogen bond to an adjacent hydroselenite group to constitute a [(SeO2OH)2]2– dimer that provides additional stabilization of the copper diselenite sheet. The [Cu(HSeO3)2] sheets alternate with the sheets consisting of zigzag–Na–Cl–Na–Cl–chains formed by Cl atoms and disordered Na sites. The chains are parallel to the c axis. The linkage between the alternating electroneutral [Cu(HSeO3)2] and [NaCl] sheets is provided by the Cu–Cl and Na–O bonds. The coordination of Na is fivefold and consists of three O and two Cl atoms. [NaCl][Cu(HSeO3)2] is a new member of the group of compounds based upon the M(HSeO3)2 layers (M2+ = Cu, Co, Cd). The prototype structure for this group is [Cu(HSeO3)2] that does not have any chemical species separating the copper hydroselenite layers. In other compounds, the interlayer space between the [Cu(HSeO3)2]0 layers is occupied by structural units of different complexity. [NaCl][Cu(HSeO3)2] can be considered as [Cu(HSeO3)2] intercalated with the NaCl layers consisting of one-dimensional–Na–Cl–Na–Cl–chains.

Exploring the Adsorption and the Potential Energy Surface of Acrylonitrile on Cu(100) and Cu(100) Coated with NaCl Layers

We present a theoretical study on the adsorption of acrylonitrile (ACN) on the Cu(100) surface. In order to check the insulating effect of an ionic film, we have also studied the adsorption of the acrylonitrile on the same metallic surface previously covered with one, two, and three NaCl monolayers. For this purpose, we have employed the density functional theory (DFT) including van der Waals dispersion forces via a DFT-D2 scheme. For these systems, a thorough ab initio molecular dynamics and static DFT study is presented. We have analyzed adsorption energies and geometries, and also explored the electronic structure and the charge transfer between the molecule and the surface. We have as well studied the potential energy surface of each system. From the dynamic point of view, several trajectories at different temperatures and conditions have been studied, in order to get an accurate description of the stability when ACN is adsorbed on the surface at a certain temperature. The studied systems present a we...

Growth of NaCl on thin epitaxial KCl films on Ag(100) studied by SPA-LEED

We investigated the growth of NaCl on thin (100)-oriented films of KCl by spot profile analysis of low energy electron diffraction (SPA-LEED). The underlying question of this investigation was how the system accommodates to the misfit of −10% between the NaCl and KCl lattices. The KCl films (3 atomic layers thick) were epitaxially grown on a Ag(100) single crystal. We studied the heteroepitaxial growth of NaCl on KCl at 300K and at 500K, respectively. At 300K, the first NaCl monolayer (ML) grows pseudomorphically on the KCl film. From the second layer onward, the NaCl lattice relaxes. The NaCl multilayers roughen, and a small rotational disorder (±4°) of the NaCl domains is observed. The roughening results from the formation of multilayer islands of limited lateral size due to the misfit to the pseudomorphic first NaCl layer. At a growth temperature of 500K, no pseudomorphic NaCl layer forms, instead relaxed multilayer island growth of NaCl is observed from the first layer onward. Similarly to the growth at 300K, we find NaCl multilayer islands of limited lateral size. For both temperatures, we explain this growth behavior by the misfit that makes the adsorption sites at the island edges of the first relaxed NaCl layer less favorable for larger islands, promoting nucleation of multilayer islands.

Topological crystalline insulator and quantum anomalous Hall states in IV-VI-based monolayers and their quantum wells

Different from the two-dimensional (2D) topological insulator, the 2D topological crystalline insulator (TCI) phase disappears when the mirror symmetry is broken, e.g., upon placing on a substrate. Here, based on a new family of 2D TCIs---SnTe and PbTe monolayers---we theoretically predict the realization of the quantum anomalous Hall effect with a Chern number $\mathcal{C}=2$ even when the mirror symmetry is broken. Remarkably, we also demonstrate that the considered materials retain their large-gap topological properties in quantum well structures obtained by sandwiching the monolayers between NaCl layers. Our results demonstrate that the TCIs can serve as a seed for observing robust topologically nontrivial phases.