Validation of system usability scale as a usability metric to evaluate voice user interfaces.

In recent years, user experience (UX) has gained importance in the field of interactive systems. To ensure its success, interactive systems must be evaluated. As most of the standardized evaluation tools are dedicated to graphical user interfaces (GUIs), the evaluation of voice-based interactive systems or voice user interfaces is still in its infancy. With the help of a well-established evaluation scale, the System Usability Scale (SUS), two prominent, widely accepted voice assistants were evaluated. The evaluation, with SUS, was conducted with 16 participants who performed a set of tasks on Amazon Alexa Echo Dot and Google Nest Mini. We compared the SUS score of Amazon Alexa Echo Dot and Google Nest Mini. Furthermore, we derived the confidence interval for both voice assistants. To enhance understanding for usability practitioners, we analyzed the Adjective Rating Score of both interfaces to comprehend the experience of an interface's usability through words rather than numbers. Additionally, we validated the correlation between the SUS score and the Adjective Rating Score. Finally, a paired sample t-test was conducted to compare the SUS score of Amazon Alexa Echo Dot and Google Nest Mini. This resulted in a huge difference in scores. Hence, in this study, we corroborate the utility of the SUS in voice user interfaces and conclude by encouraging researchers to use SUS as a usability metric to evaluate voice user interfaces.

Salacia spp.: recent insights on biotechnological interventions and future perspectives.

The plants of the genus Salacia L. are the storehouse of several bioactive compounds, and are involved in treating human diseases and disorders. Hitherto, a number of reports have been published on in vitro biotechnology as well as microbial involvement in the improvement of Salacia spp. The present review provides comprehensive insights into biotechnological interventions such as tissue culture for plant propagation, in vitro cultures, and endophytic microbes for up-scaling the secondary metabolites and biological potential of Salacia spp. Other biotechnological interventions such as molecular markers and bio-nanomaterials for up-grading the prospective of Salacia spp. are also considered. The in vitro biotechnology of Salacia spp. is largely focused on plant regeneration, callus culture, cell suspension culture, somatic embryogenesis, and subsequent ex vitro establishment of the in vitro-raised plantlets. The compiled information on tissue cultural strategies, involvement of endophytes, molecular markers, and nanomaterials will assist the advanced research related to in vitro manipulation, domestication, and commercial cultivation of elite clones of Salacia spp. Moreover, the genetic diversity and other molecular-marker based assessments will aid in designing conservation policies as well as support upgrading and breeding initiatives for Salacia spp. KEY POINTS: • Salacia spp. plays a multifaceted role in human health and disease management. • Critical and updated assessment of tissue culture, endophytic microbes, metabolites, molecular markers, and bio-nanomaterials of Salacia spp. • Key shortcomings and future research directions for Salacia biotechnology.

Modeling Henry's law and phase separations of water-NaCl-organic mixtures with solvation and ion-pairing.

Empirical measurements of solution vapor pressure of ternary acetonitrile (MeCN) H2O-NaCl-MeCN mixtures were recorded, with NaCl concentrations ranging from zero to the saturation limit, and MeCN concentrations ranging from zero to an absolute mole fraction of 0.64. After accounting for speciation, the variability of the Henry's law coefficient at vapor-liquid equilibrium (VLE) of MeCN ternary mixtures decreased from 107% to 5.1%. Solute speciation was modeled using a mass action solution model that incorporates solute solvation and ion-pairing phenomena. Two empirically determined equilibrium constants corresponding to solute dissociation and ion pairing were utilized for each solute. When speciation effects were considered, the solid-liquid equilibrium of H2O-NaCl-MeCN mixtures appear to be governed by a simple saturation equilibrium constant that is consistent with the binary H2O-NaCl saturation coefficient. Further, our results indicate that the precipitation of NaCl in the MeCN ternary mixtures was not governed by changes in the dielectric constant. Our model indicates that the compositions of the salt-induced liquid-liquid equilibrium (LLE) boundary of the H2O-NaCl-MeCN mixture correspond to the binary plateau activity of MeCN, a range of concentrations over which the activity remains largely invariant in the binary water-MeCN system. Broader comparisons with other ternary miscible organic solvent (MOS) mixtures suggest that salt-induced liquid-liquid equilibrium exists if: (1) the solution displays a positive deviation from the ideal limits governed by Raoult's law; and (2) the minimum of the mixing free energy profile for the binary water-MOS system is organic-rich. This work is one of the first applications of speciation-based solution models to a ternary system, and the first that includes an organic solute.

Enhancing the Permselectivity of Thin-Film Composite Membranes Interlayered with MoS2 Nanosheets via Precise Thickness Control.

The demand for highly permeable and selective thin-film composite (TFC) nanofiltration membranes, which are essential for seawater and brackish water softening and resource recovery, is growing rapidly. However, improving and tuning membrane permeability and selectivity simultaneously remain highly challenging owing to the lack of thickness control in polyamide films. In this study, we fabricated a high-performance interlayered TFC membrane through classical interfacial polymerization on a MoS2-coated polyethersulfone substrate. Due to the enhanced confinement effect on the interface degassing and the improved adsorption of the amine monomer by the MoS2 interlayer, the MoS2-interlayered TFC membrane exhibited enhanced roughness and crosslinking. Compared to the control TFC membrane, MoS2-interlayered TFC membranes have a thinner polyamide layer, with thickness ranging from 60 to 85 nm, which can be tuned by altering the MoS2 interlayer thickness. A multilayer permeation model was developed to delineate and analyze the transport resistance and permeability of the MoS2 interlayer and polyamide film through the regression of experimental data. The optimized MoS2-interlayered TFC membrane (0.3-inter) had a 96.8% Na2SO4 rejection combined with an excellent permeability of 15.9 L m-2 h-1 bar-1 (LMH/bar), approximately 2.4 times that of the control membrane (6.6 LMH/bar). This research provides a feasible strategy for the rational design of tunable, high-performance NF membranes for environmental applications.

Novel Positively Charged Metal-Coordinated Nanofiltration Membrane for Lithium Recovery.

Nanofiltration (NF) with high water flux and precise separation performance with high Li+/Mg2+ selectivity is ideal for lithium brine recovery. However, conventional polyamide-based commercial NF membranes are ineffective in lithium recovery processes due to their undesired Li+/Mg2+ selectivity. In addition, they are constrained by the water permeance selectivity trade-off, which means that a highly permeable membrane often has lower selectivity. In this study, we developed a novel nonpolyamide NF membrane based on metal-coordinated structure, which exhibits simultaneously improved water permeance and Li+/Mg2+ selectivity. Specifically, the optimized Cu-m-phenylenediamine (MPD) membrane demonstrated a high water permeance of 16.2 ± 2.7 LMH/bar and a high Li+/Mg2+ selectivity of 8.0 ± 1.0, which surpassed the trade-off of permeance selectivity. Meanwhile, the existence of copper in the Cu-MPD membrane further enhanced anti-biofouling property and the metal-coordinated nanofiltration membrane possesses a pH-responsive property. Finally, a transport model based on the Nernst-Planck equations has been developed to fit the water flux and rejection of uncharged solutes to the experiments conducted. The model had a deviation below 2% for all experiments performed and suggested an average pore radius of 1.25 nm with a porosity of 21% for the Cu-MPD membrane. Overall, our study provides an exciting approach for fabricating a nonpolyamide high-performance nanofiltration membrane in the context of lithium recovery.

Publisher Correction: Multifunctional nanocoated membranes for high-rate electrothermal desalination of hypersaline waters.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Multifunctional nanocoated membranes for high-rate electrothermal desalination of hypersaline waters.

Surface heating membrane distillation overcomes several limitations inherent in conventional membrane distillation technology. Here we report a successful effort to grow in situ a hexagonal boron nitride (hBN) nanocoating on a stainless-steel wire cloth (hBN-SSWC), and its application as a scalable electrothermal heating material in surface heating membrane distillation. The novel hBN-SSWC provides superior vapour permeability, thermal conductivity, electrical insulation and anticorrosion properties, all of which are critical for the long-term surface heating membrane distillation performance, particularly with hypersaline solutions. By simply attaching hBN-SSWC to a commercial membrane and providing power with an a.c. supply at household frequency, we demonstrate that hBN-SSWC is able to support an ultrahigh power intensity (50 kW m-2) to desalinate hypersaline solutions with exceptionally high water flux (and throughput), single-pass water recovery and heat utilization efficiency while maintaining excellent material stability. We also demonstrate the exceptional performance of hBN-SSWC in a scalable and compact spiral-wound electrothermal membrane distillation module.

Mechanism of Heterogeneous Fenton Reaction Kinetics Enhancement under Nanoscale Spatial Confinement.

Nanoscale catalysts that can enable Fenton-like chemistry and produce reactive radicals from hydrogen peroxide activation have been extensively studied in order to overcome the limitations of homogeneous Fenton processes. Despite several advantageous features, limitation in mass transfer of short-lived radical species is an inherent drawback of the heterogeneous system. Here, we present a mechanistic foundation for the way spatial confinement of Fenton chemistry at the nanoscale can significantly enhance the kinetics of radical-mediated oxidation reactions-pollutant degradation in particular. We synthesized a series of Fe3O4-functionalized nanoreactors with precise pore dimensions, based on an anodized aluminum oxide template, to enable quantitative analysis of nanoconfinement effects. Combined with computational simulation of spatial distribution of radicals, we found that hydroxyl radical concentration was strongly dependent on the distance from the surface of Fenton catalysts. This distance dependency significantly influences the gross reaction kinetics and accounts for the observed nanoconfinement effects. We further found that a length scale below 25 nm is critical to avoid the limitation of short-lived species diffusion and achieve kinetics that are orders of magnitude faster than those obtained in a batch suspension of heterogeneous catalysts. These findings suggest a new strategy to develop an innovative heterogeneous catalytic system with the most effective use of hydroxyl radicals in oxidation treatment scenarios.

Relating Selectivity and Separation Performance of Lamellar Two-Dimensional Molybdenum Disulfide (MoS2) Membranes to Nanosheet Stacking Behavior.

Increased demand for highly selective and energy-efficient separations processes has stimulated substantial interest in emerging two-dimensional (2D) nanomaterials as a potential platform for next-generation membranes. However, persistently poor separation performance continues to hinder the viability of many novel 2D-nanosheet membranes in desalination applications. In this study, we examine the role of the lamellar structure of 2D membranes on their performance. Using self-fabricated molybdenum disulfide (MoS2) membranes as a platform, we show that the separation layer of 2D nanosheet frameworks not only fails to demonstrate water-salt selectivity but also exhibits low rejection toward dye molecules. Moreover, the MoS2 membranes possess a molecular weight cutoff comparable to its underlying porous support, implying negligible selectivity of the MoS2 layer. By tuning the nanochannel size through intercalation with amphiphilic molecules and analyzing mass transport in the lamellar structure using Monte Carlo simulations, we reveal that small imperfections in the stacking of MoS2 nanosheets result in the formation of catastrophic microporous defects. These defects lead to a precipitous reduction in the selectivity of the lamellar structure by negating the interlayer sieving mechanism that prevents the passage of large penetrants. Notably, the imperfect stacking of nanosheets in the MoS2 membrane was further verified using 2D X-ray diffraction measurements. We conclude that developing a well-controlled fabrication process, in which the lamellar structure can be carefully tuned, is critical to achieving defect-free and highly selective 2D desalination membranes.

Solute displacement in the aqueous phase of water-NaCl-organic ternary mixtures relevant to solvent-driven water treatment.

Twelve water miscible organic solvents (MOS): acetone, tetrahydrofuran, isopropanol, acetonitrile, dimethyl sulfoxide, 1,4-dioxane, dimethylacetamide, N-methyl-2-pyrrolidone, trifluoroethanol, isopropylamine, dimethylformamide, and dimethyl ether (DME) were used to produce ternary mixtures of water-NaCl-MOS relevant to MOS-driven fractional precipitation. The aqueous-phase composition of the ternary mixture at liquid-liquid equilibrium and liquid-solid endpoint was established through quantitative nuclear magnetic resonance and mass balance. The results highlight the importance of considering the hydrated concentrations of salts and suggest that at high salt concentrations and low MOS concentration, the salt concentration is governed by competition between the salt ions and MOS molecules. Under these conditions a LS phase boundary is established, over which one mole of salt is replaced by one mole of MOS (solute displacement). At higher MOS concentrations, MOS with higher water affinity deviate from the one-to-one solute exchange but maintain a LS boundary with a homogenous liquid phase, while MOS with lower water affinity form a liquid-liquid phase boundary. DME is found to function effectively as an MOS for fractional precipitation, precipitating 97.7% of the CaSO4 from a saturated solution, a challenging scalant. DME-driven water softening recycles the DME within the system improving the atom-efficiency over existing seawater desalination pretreatments by avoiding chemical consumption.

Minimal and zero liquid discharge with reverse osmosis using low-salt-rejection membranes.

Minimal and zero liquid discharge (MLD/ZLD) are wastewater management strategies that are attracting heightened attention worldwide. While conventional reverse osmosis (RO) has been proposed as a promising technology in desalination and MLD/ZLD processes, its application is limited by the maximum hydraulic pressures that current RO membranes and modules can withstand. In this study, we develop low-salt-rejection RO (LSRRO), a novel staged RO process, that employs low-salt-rejection membranes to desalinate or concentrate highly saline feed streams, requiring only moderate hydraulic pressures. Based on process modeling, we demonstrate that LSRRO can overcome the hydraulic pressure limitations of conventional RO, achieving hypersaline brine salinities (>4.0 M NaCl or 234 g L-1 NaCl) that are required for MLD/ZLD applications, without using excessively high hydraulic pressures (≤70 bar). In addition, we show that the energy efficiency of LSSRO is substantially higher than traditional thermally-driven phase-change-based technologies, such as mechanical vapor compressor (MVC). For example, to concentrate a saline feed stream from 0.1 to 1.0 M NaCl, the specific energy consumption (SEC) of 4-stage LSRRO ranges from 2.4 to 8.0 kWh of electrical energy per m3 of feedwater treated, around four times less than that of MVC, which requires 20-25 kWhe m-3. Furthermore, compared to osmotically mediated RO technologies that require bilateral countercurrent stages to treat hypersaline brines, LSRRO is eminently more practical as it can be readily implemented by using 'loose' RO or nanofiltration membranes in conventional RO. Our study highlights LSRRO's potential for energy efficient brine concentration using moderate hydraulic pressures, which would drastically improve the energetic and economic performance of MLD/ZLD processes.

Monte Carlo Simulations of Framework Defects in Layered Two-Dimensional Nanomaterial Desalination Membranes: Implications for Permeability and Selectivity.

Two-dimensional nanomaterial (2-D NM) frameworks, especially those comprising graphene oxide, have received extensive research interest for membrane-based separation processes and desalination. However, the impact of horizontal defects in 2-D NM frameworks, which stem from nonuniform deposition of 2-D NM flakes during layer build-up, has been almost entirely overlooked. In this work, we apply Monte Carlo simulations, under idealized conditions wherein the vertical interlayer spacing allows for water permeation while perfectly excluding salt, on both the formation of the laminate structure and molecular transport through the laminate. Our simulations show that 2-D NM frameworks are extremely tortuous (tortuosity ≈103), with water permeability decreasing from 20 to <1 L m-2 h-1 bar-1 as thickness increased from 8 to 167 nm. Additionally, we find that framework defects allow salt to percolate through the framework, hindering water-salt selectivity. 2-D NM frameworks with a packing density of 75%, representative of most 2-D NM membranes, are projected to achieve <92% NaCl rejection at a water permeability of <1 L m-2 h-1 bar-1, even with ideal interlayer spacing. A high packing density of 90%, which to our knowledge has yet to be achieved, could yield comparable performance to current desalination membranes. Maximizing packing density is therefore a critical technical challenge, in addition to the already daunting challenge of optimizing interlayer spacing, for the development of 2-D NM membranes.

Nanophotonics-enabled solar membrane distillation for off-grid water purification.

With more than a billion people lacking accessible drinking water, there is a critical need to convert nonpotable sources such as seawater to water suitable for human use. However, energy requirements of desalination plants account for half their operating costs, so alternative, lower energy approaches are equally critical. Membrane distillation (MD) has shown potential due to its low operating temperature and pressure requirements, but the requirement of heating the input water makes it energy intensive. Here, we demonstrate nanophotonics-enabled solar membrane distillation (NESMD), where highly localized photothermal heating induced by solar illumination alone drives the distillation process, entirely eliminating the requirement of heating the input water. Unlike MD, NESMD can be scaled to larger systems and shows increased efficiencies with decreased input flow velocities. Along with its increased efficiency at higher ambient temperatures, these properties all point to NESMD as a promising solution for household- or community-scale desalination.