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The current challenges in dewatering oil sand mature fine tailings (MFTs) by flocculation using a single flocculant include the requirement of very high doses and high cost, inefficient flocculation, and low content of solids in sediment. The obtained flocculated sediment with less than

Traumatic brain injury (TBI) is a health problem of global concern because of its serious adverse effects on public health and social economy. A technique that can be used to precisely detect TBI is highly demanded. Here, we report on a synchrotron radiation-based Fourier transform infrared (SR-FTIR) microspectroscopic imaging technique that can be exploited to identify TBI-induced injury by examining model mouse brain tissue slices. The samples were first examined by conventional histopathological techniques including hematoxylin and eosin (H&E) staining and 2,3,5-triphenyltetrazolium chloride staining and then spectroscopically imaged by SR-FTIR. SR-FTIR results show that the contents of protein and nucleic acid in the injured region are lower than their counterparts in the normal region. The injured and normal regions can be unambiguously distinguished from each other by the principle component analysis of the SR-FTIR spectral data corresponding to protein or nucleic acid. The images built from the spectral data of protein or nucleic acid clearly present the injured region of the brain tissue, which is in good agreement with the H&E staining image and optical image of the sample. Given the label-free and fingerprint features, the demonstrated method suggests potential application of SR-FTIR spectroscopic mapping for the digital and intelligent diagnosis of TBI by providing spatial and chemical information of the sample simultaneously.

A combinative approach for chemical analysis makes it possible to distinguish a mixture of a large number of compounds from other mixtures in a single step. This work demonstrates a combinative analysis approach using surface nanodroplets for integrating nanoextraction and colorimetric reactions for the identification of multicomponent mixtures. The model analytes are acidic compounds dissolved in an oil that are extracted into aqueous droplets on a solid substrate. The proton from acid dissociation reacts with the halochromic chemical compounds inside the droplets, leading to the color change of the droplets. The rate of the colorimetric reaction exhibits certain specificity for the acid type, distinguishing acid mixtures with the same pH value. The underlying principle is that the acid transport rate is associated with the partition coefficient and the dissociation constant of the acid, as well as to the concentration in the oil. As a demonstration, we showed that droplet-based combinative analysis can be applied for anti-counterfeiting of various alcoholic spirits by comparing the decoloration time of organic acid mixtures in the spirits. The readout can be done by a common hand-hold mobile phone.

This study systematically investigated the phytotoxicity of chicken manure co-composted with tobacco powder and mushroom substrate on seed germination during active phase of composting. All compost products met the sanitation requirements specified in the Chinese national standard; however, only the mushroom substrate compost satisfied the maturity standard. From day 28, the composting entered the end of active phase and the concentrations of K+, Zn2+, Na+, Cu2+ and Fe3+ decreased gradually. Redundancy analysis indicated that the germination index, catalase and peroxidase activities was positively correlated with K+, Zn2+, Na+, Cu2+, Fe3+ and NO3--N, and negatively correlated with NH4+-N, Mg2+ and Ca2+, among which the most significant ions were Fe3+, Mg2+ and Zn2+ for all treatments. The malondialdehyde concentration of germinated seeds had adverse correlation with the above ions parameters.

The compartmentalization of chemical reactions within droplets has advantages in low costs, reduced consumption of reagents, and increased throughput. Reactions in small droplets have also been shown to greatly accelerate the rate of many chemical reactions. The accelerated growth rate of nanobubbles from nanodroplet reactions is demonstrated in this work. The gaseous products from the reaction at the nanodroplet surface promoted nucleation of hydrogen nanobubbles within multiple organic liquid nanodroplets. The nanobubbles were confined within the droplets and selectively grew and collapsed at the droplet perimeter, as visualized by microscopy with high spatial and temporal resolutions. The growth rate of the bubbles was significantly accelerated within small droplets and scaled inversely with droplet radius. The acceleration was attributed to confinement from the droplet volume and effect from the surface area on the interfacial chemical reaction for gas production. The results of this study provide further understanding for applications in droplet enhanced production of nanobubbles and the on-demand liberation of hydrogen.

To understand the unexpected and puzzling long-term stability of nanoscale gas bubbles, it is crucial to probe their nature and intrinsic properties. We report herein synchrotron-based scanning transmission X-ray microscopy (STXM) evidence of highly condensed oxygen gas molecules trapped as surface nanobubbles. Remarkably, the analysis of absorption spectra of a single nanobubble revealed that the oxygen density inside was 1-2 orders of magnitude higher than that in atmospheric pressure, and these bubbles were found in a highly saturated liquid environment with the estimated oxygen concentration to be hundreds of times higher than the known oxygen solubility in equilibrium. Molecular dynamics simulations were performed to investigate the stability of surface nanobubbles on a heterogeneous substrate in gas-oversaturated water. These results indicated that gas molecules within confinement such as the nanobubbles could maintain a dense state instead of the ideal gas state, as long as their surrounding liquid is supersaturated. Our findings should help explain the surprisingly long lifetime of the nanobubbles and shed light on nanoscale gas aggregation behaviors.

The electrocatalytic CO2 reduction to yield C2 products is of particular interest in solar-to-fuel conversion schemes. The nanocrystalline oxide derived copper (ODCu) electrodes are specifically attractive due to their high faradaic efficiency towards C2 hydrocarbons like ethylene, ethane, acetate and ethanol. However, the mechanistic understanding of this special selectivity is still an impediment. In this work, ODCu is obtained from Cu2O nanowires and employed for electrocatalytic CO2 reduction, during which ethylene is found to be the major product with a faradaic efficiency of 65% at -0.8 V (vs. RHE). By in situ photoresponse measurement, combined with the ex situ structure and composition analysis, Cu2O is demonstrated to be persistent on the surface of ODCu throughout the CO2 reduction reaction (CO2RR) even at high applied bias (-1.0 V vs. RHE), while Cu2O is not present on the bulk Cu foil. Density functional theory calculations are employed to further investigate the correlation between the surface Cu2O on ODCu and its C2 selectivity performance, which is attributed to the orbital interactions between the persistent oxide and CO2 reduction intermediates. It should be noted that uncovering the active sites is the initial step to understand the surface reaction chemistry in CO2RR; here, we propose that the presence of Cu2O is the key for C2 selectivity during CO2RR in the ODCu system, which may facilitate the development of highly efficient catalysts.

Surface-bound nanomaterials are widely used in clean energy techniques from lithium batteries, solar-driven evaporation in desalination to hydrogen production by photocatalytic electrolysis. Reactive surface nanodroplets may potentially streamline the process of fabrication of a range of surface-bound nanomaterials invoking biphasic reactions at interfaces. In this work, we demonstrate the feasibility of reactive surface nanodroplets for in-situ synthesis and anchoring of nanocaps of metal oxides with tailored porous structures. Spatial arrangement and surface coverage of nanocaps are predetermined during the formation of reactive nanodroplets, while the crystalline structures of metal oxides can be controlled by thermal treatment of organometallic nanodroplets produced from the biphasic reactions. Notably, tuning the ratio of reactive and non-reactive components in surface nanodroplets enables the formation of porous nanocaps that can double photocatalytic efficiency in the degradation of organic contaminants in water, compared to smooth nanocaps. In total, we demonstrate in-situ fabrication of four types of metal oxides in the shape of nanocaps. Our work shows that reactive surface nanodroplets may open a door to a general, fast and tuneable route for preparing surface-bound metal oxides. This fabrication approach may help develop new nanomaterials needed for photocatalytic reactions, wastewater treatment, optical focusing, solar energy conversion and other clean energy techniques.

The oil-water partition coefficient of organic compounds is an essential parameter for the determination of their behaviors in environments, food, drug delivery, and biomedical systems, just to name a few. In this work, we establish a highly efficient approach to quantify the partition/distribution coefficient using surface femtoliter droplets. In our approach, droplets of 1-octanol were produced on the surface of a solid substrate in contact with the flow of an aqueous solution of the analyte. The analyte was rapidly enriched in the droplets from the flow and reached the partition equilibrium in a few seconds. The entire procedure was automated by continuous solvent exchange, and the analyte partition in the droplets was quantified from the in situ UV-vis spectrum collected by a microspectrophotometer. Our approach was validated for several substances with the octanol-water partition/distribution coefficient ranging from -1.5 to 4, where our results were in good agreement with the values reported in the literature. This method took ∼3 min to detect one analyte with the volume of the organic solvent at ∼50 μL. Thus, our surface droplet platform can greatly minimize the consumption of both solvent and analytes and can shorten the time for the determination of the partition of new compounds, which overcomes the drawbacks of the traditional shake-flask method and presents excellent reproducibility, high accuracy, cost-effectiveness, and labor-saving operation. The highly efficient micro/nanoextraction, partition, and real-time detection enabled by the surface droplets has the potential for many other high-throughput applications.

Fabrication of hybrid system coupling inorganic semiconductor photosensitizer with molecular catalyst provides a promising approach to achieve highly efficient CO2 reduction into solar fuels, as the semiconductor nanomaterials can meet the prerequisites of visible-light photoresponse and high charge-separation efficiency for achieving high photocatalytic efficiency. In this work, CdS/Bi2S3 heterostructures have been prepared via an ion-exchange reaction and employed as the photosensitizer to couple with tetra(4-carboxyphenyl)porphyrin iron(III) chloride (FeTCPP) molecular catalyst for photoreduction of CO2 into CO and H2 under visible-light irradiation. The sulfur vacancy in CdS surface can be reduced by the formation of CdS/Bi2S3 heterostructure. The content of Bi2S3 can be modulated via tailoring the ion-exchange reaction time. The resulting effect on the performace of CO2 photoreduction has been investigated in detail. Benefiting from the enhanced separation and utilization of charge carriers, CdS/Bi2S3-0.5 h/FeTCPP hybrid catalyst exhibits 8.2 times CO yield (1.93 mmol/g/h) and 1.7 times H2 yield (6.08 mmol/g/h) of CdS/FeTCPP hybrid catalyst. More important, the results of energy level alignment, electron spin resonance and photocatalysis indicate that electron-transfer direction can be changed once the CdS/Bi2S3 heterostructure is coupled with FeTCPP. In the CdS/Bi2S3 heterostructure, electrons transfer mainly from the conduction band of CdS to Bi2S3, while it is mainly from the conduction band of CdS to FeTCPP in the CdS/Bi2S3/FeTCPP hybrid.

A fundamental process culminating in the mechanisms of plant-pathogen interactions is the regulation of trophic divergence into biotrophic, hemibiotrophic, and necrotrophic interactions. Plant hormones, of almost all types, play significant roles in this regulatory apparatus. In plant-pathogen interactions, two classical mechanisms underlying hormone-dependent trophic divergence are long recognized. While salicylic acid dominates in the execution of host defense response against biotrophic and early-stage hemibiotrophic pathogens, jasmonic acid, and ethylene are key players facilitating host defense response against necrotrophic and later-stage hemibiotrophic pathogens. Evidence increasingly suggests that trophic divergence appears to be modulated by more complex signaling networks. Acting antagonistically or agonistically, other hormones such as auxins, cytokinins, abscisic acid, gibberellins, brassinosteroids, and strigolactones, as well as nitric oxide, are emerging candidates in the regulation of trophic divergence. In this review, the latest advances in the dynamic regulation of trophic divergence are summarized, emphasizing common and contrasting hormonal and nitric oxide signaling strategies deployed in plant-pathogen interactions.

Enhancement of the detection signal of fluorescence microscopy in highly diluted solutions is of great importance in chemical analysis, sensing, and bioassay applications. Surface nanodroplets with atto- to femto-liter volumes are promising tools for sensitive online detection by integrating their extremely efficient nano-extraction and optical advantages. In this paper, the development of novel basic units of nanodroplets-in-a-microdroplet by simple solvent exchange is reported. The encapsulated nanodroplets are applied for ultrasensitive and online detection in fluorescence imaging. The biphasic nature of the droplet composite enables simultaneous extraction and enrichment of both hydrophobic and hydrophilic compounds. Furthermore, the desirable lensing effect of the curved surface of the nanodroplets enhances the collection of light emitted from the fluorophore extracted in the droplets by ≈60-fold, allowing sensitive and quantitative analysis of the fluorophore using fluorescence microscopy. The results highlight the potential of encapsulated nanodroplets as a simple and innovative method of signal enhancement in chemical analysis. By integrating selective concentration, extraction, and sensitive detection, the encapsulated nanodroplets reported here may have broad applications in many chemical and biological matrices.

Colorimetric detection of dopamine has the advantage of simplicity in operation and instrumentation. Herein, a highly sensitive and selective colorimetric biosensor with fast response has been developed by using 4′-aminobenzo-18-crown-6 (ABCE) and 4-mercaptophenyl boronic acid (MPBA) modified Au nanoparticles. The modified probe shows an excellent detection limit of 6.0 nM of dopamine at a S/N of 2.01 and about 46 nM at a S/N of 3 within microseconds response. It exhibits excellent detection selectivity even in 1000-fold excess of many different interferents like metal ions, uric acid and ascorbic acid. All these may make it fulfill the requirements for in vivo analysis.

Isothermal compressibility, κ T , and isobaric thermal expansivity, α P , can describe the volumetric behavior of a given fluid in response to the change in pressure and temperature, respectively. They are two important parameters that are used in the simulation and modeling of many petroleum and chemical processes. Isothermal compressibility and isobaric thermal expansivity can be calculated with empirical correlations or thermodynamic models, but these methods are not sufficiently accurate. Cubic equations of state (CEOSs) are widely used in the petroleum and chemical industry to describe the phase behavior of fluid mixtures. It is recognized that one of the deficiencies of CEOSs is their inaccuracy in predicting liquid-phase volumes. The volume translation (VT) strategy was proposed to overcome this deficiency, which could significantly improve the performance of CEOSs in predicting volumetric properties. With recent development in the volume-translated equations of state (VT-EOSs), κ T and α P could be predicted more accurately by VT-EOSs. However, the prediction accuracy of κ T and α P by different VT-EOSs has not been comprehensively investigated. In this work, κ T and α P of two pure example fluids (CH4 and CO2) are predicted by seven different VT models: one constant VT model, two linear temperature-dependent VT models, two exponential temperature-dependent VT models, and two temperature-pressure-dependent VT models. The accuracy of each model is evaluated by comparing the predictions with the NIST pseudo-experimental data for the liquid phase, the vapor phase, and the supercritical phase. The predicted results show that the distance-function-based temperature-pressure-dependent VT models exhibit relatively better performance in predicting κ T and α P than the temperature-dependent and the constant VT models. This is because the distance function is a function of both temperature and pressure, which allows the distance-function-based VTs to provide more accurate volume corrections for most of the phase regions and thus can lead to better accuracy in predicting κ T and α P . According to the overall prediction accuracy, the VT-PR EOS model proposed by Abudour et al. (2012) provides the most accurate predictions of κ T , while the VT-SRK EOS model proposed by Chen and Li (2020) provides the most accurate predictions of α P . The findings of this study can help to predict κ T and α P of pure substances at different temperature and pressure conditions by using the most accurate VT-EOS and provide insights for further improvement of volume translation strategies.

Sodium-ion capacitors (NICs) are rising as a promising candidate for next-generation energy storage systems owing to the abundance of sodium resources and the better performance than that of their lithium-ion capacitor counterparts. The design of the pseudocapacitive electrode materials is of great significance for an integrated device to have high energy and power densities. In this work, activated hard carbon (AHC) with a high surface area and abundant oxygen-containing functional groups is synthesized via the KOH activation of controllable carbon spheres that act as a special type of precursors. The AHC can be used as a supercapacitor-type material because it exhibits excellent properties as anode or cathode of sodium-ion batteries. The integrated symmetrical NIC with the AHC as both anode and cathode is superior to most previously reported all-carbon-based capacitors in terms of electrochemical performance. Benefiting from the oxygen-containing groups on the surface of the AHC, the pseudocapacitor shows an energy density of 43 Wh kg−1 at a power density of 3724 W kg−1 after 5000 cycles. This study not only provides a novel electrode material for NICs but also deepens the understanding of all-carbon-based capacitors.

The hybrid coupling between inorganic semiconductor and molecular catalyst can provide a promising approach for the construction of highly efficient and selective photocatalytic CO2 reduction systems. This hybrid system can take full advantage of the strong light harvesting capability of semiconductor and high selectivity of molecular catalyst. The interaction linker bridging the semiconductor and molecular catalyst plays an important role in supplying efficient electron transfer channels. In this study, both CdS with and without ethylenediamine functionalization (i.e., CdS-EF and CdS) have been successfully synthesized and further respectively coupled with tetra(4-carboxyphenyl)porphyrin iron(III) chloride (FeTCPP) for CO2 photoreduction. It is found that CdS-EF exhibits inferior photocatalytic activity to CdS, while CdS-EF/FeTCPP hybrid photocatalyst shows much higher activity than CdS/FeTCPP. This is because hydrogen bonding exists between the amino groups in CdS-EF and carboxyl groups in FeTCPP, which can act as electron transfer channels from CdS to FeTCPP in the obtained hybrid system.

Microscopic lenses are paramount in solar energy harvesting, optical devices, and imaging technologies. This work reports an extraordinary focusing effect exhibited by a surface nanolens (i.e., with at least one dimension of subwavelength) that is situated in an evanescent field from the total internal reflection (TIR) of light illuminated to the supporting substrate above the critical angle. Our measurements show that the position, shape, and size of the surface area with enhanced light intensity are determined by the geometry of the nanolens and the incident angle, in good agreement with simulation results. This strong focusing effect of the surface nanolens is shown to significantly promote the plasmonic effect of deposited gold nanoparticles on the lens surface inlight conversion and to vaporize surrounding water to microbubbles by using low laser power. This work further demonstrates that the light redistribution by the surface nanolens in TIR enables a range of novel applications in selectively local visualization of specimens in fluorescence imaging, optical trapping of colloids from an external flow, and selective materials deposition from photoreactions., Small scale lenses demonstrated a remarkable focusing effect when illuminated near the critical angle. This attribute yielded an enhanced plasmonic bubble formation, fluorescence signal, and local photoreaction.

Photocatalytic reduction of CO 2 into value-added chemicals is particularly attractive as it could produce renewable energy and capture greenhouse gas. Photoreduction of CO 2 can be realized over molecular and inorganic catalysts. The former usually exhibit high activity, but low stability and often inactive under visible-light irradiation; the latter has low activity, but good stability. Here we use g-C 3 N 4 nanosheets as the photosensitizer to integrate with Fe tetra(4-carboxylphenyl)porphyrin chloride (FeTCPP) molecular catalyst. Besides π-π stacking between tri- s -triazine unit and porphyrin, the carboxyl group modified Fe porphyrin is used for the first time in CO 2 photoreduction so as to form hydrogen bonding with the rich amino groups in g-C 3 N 4 nanosheets. g-C 3 N 4 /FeTCPP heterogeneous catalysts are prepared via a facile self-assembly approach, in which light harvest is separated from catalysis spatially and temporally. The obtained g-C 3 N 4 /FeTCPP heterogeneous catalysts exhibit high activity for CO 2 reduction under visible-light irradiation, with CO yield of 6.52 mmol g −1 in 6 h and selectivity up to 98%. Fluorescence data indicate that the electrons can efficiently transfer from the g-C 3 N 4 nanosheets to FeTCPP. The mechanism for CO 2 reduction over the g-C 3 N 4 /FeTCPP heterogeneous catalysts is proposed based on the results of quasi in-situ ESR and UV–vis measurements. This work may pave a facile approach for fabricating the high-efficient photocatalysts for CO 2 reduction, as well as better understanding the related mechanism.

Mesoporous solids have been widely used in various biomedical areas such as drug delivery and tumor therapy. Although deformability has been recognized as a prime important characteristic influencing cellular uptake, the synthesis of deformable mesoporous solids is still a great challenge. Herein, deformable thioether-, benzene-, and ethane-bridged hollow periodic mesoporous organosilica (HPMO) nanocapsules have successfully been synthesized for the first time by a preferential etching approach. The prepared HPMO nanocapsules possess uniform diameters (240–310 nm), high surface areas (up to 878 m2·g–1), well-defined mesopores (2.6–3.2 nm), and large pore volumes (0.33–0.75 m3·g–1). Most importantly, the HPMO nanocapsules simultaneously have large hollow cavities (164–270 nm), thin shell thicknesses (20–38 nm), and abundant organic moiety in the shells, which endow a lower Young’s modulus (EY) of 3.95 MPa than that of solid PMO nanoparticles (251 MPa). The HPMOs with low EY are intrinsically flexible and d...

Construction of solid solution semiconductors has attracted much attention in photocatalysis by virtue of their tunable elemental composition and band structure. The integration of semiconductor sensitizers with molecular catalysts provides a promising way to fabricate highly efficient, selective and stable systems for CO2 photoreduction. Here ZnxCd1-xS (ZCS) solid solutions with a well-defined floccule-like morphology composed of nanoribbons are synthesized and used as the photosensitizer to couple with tetra(4-carboxyphenyl)porphyrin iron(iii) chloride (FeTCPP) for CO2 reduction. The effects of changes in surface atoms of the ZCS solid solution on the performance of CO2 photoreduction are investigated. Regardless of the presence of FeTCPP, our results show that the introduction of Zn into CdS can affect the activity and selectivity of CO2 photoreduction, as well as the stability of the obtained photocatalysts. More importantly, the presence of Zn can build efficient electron transfer channels from ZCS to FeTCPP and, thus, greatly facilitate the interfacial charge transfer. Benefitting from the efficient charge separation and electron transfer, ZCS-1/FeTCPP (Zn0.14Cd0.84S/FeTCPP) exhibits the highest activity for CO2 reduction under visible-light irradiation, with a CO yield of 1.28 μmol and a selectivity up to 93% after 4 h.

The heterobimetallic ruthenium–cobalt catalytic system exhibited good catalytic performance and reusability in the reductive alkoxycarbonylation of olefins with carbon dioxide. Compared to the previous system only consisting of ruthenium catalyst, the binary catalyst system effectively reduced the usage of noble metal and ionic liquid additives. The respective contribution of ruthenium and cobalt catalysts in this multiple-step catalytic process was investigated by a series of condition-controlled experiments. The evolution of the ruthenium catalyst and the occurrence of alkene hydrogenation during the reaction was explained by theortical calculations.

Formation and growth of femtoliter droplets on surface microstructures are important in many fundamental and practical interfacial processes, such as water collection, vapour condensation in cooling devices, drop self-removal on anti-icing surfaces and fabrication of droplet-templated functional microstructures. In this work, we experimentally and theoretically investigate the growth of femtoliter oil-like liquid on the microlens surrounded by a hydrophilic planar area. The droplets were produced by solvent exchange, a process where the droplets nucleate and grow from an oversaturation created by displacing a good solvent by a poor solvent of the droplet liquid. Our results showed that the droplet fully coats the lens surface and the contact angle of the droplet relative to the flat surface is finely tuned over a large range by the droplet volume. The growth of the droplet on a microlens is largely described by the constant contact radius model. To demonstrate the new opportunities provided by the controlled formation of the droplet situated on a microlens, we will show a simple and effective approach for production of arrays of composite microlenses consisting of two types of polymers with different refractive indices. A high curvature of the composite microlens results in desirable diffraction patterns with potential application for enhanced light harvesting. Moreover, we demonstrate that extraction of traces of a hydrophobic solute from the flow is much faster as the droplet is lifted up from the channel wall by the microlens, promising a time effective in situ detection process in narrow channels.

Equilibrium solubility determination and model correlation were performed in the present research for the systems formed by solid solute of thiabendazole and binary aqueous blends of acetonitrile, methanol, n-propanol and isopropanol. Experiments at temperatures ranging from 283.15 to 323.15 K were conducted by the use of the shake-flask saturation technique at 101.2 kPa. For the given binary solvent blends, the minimum mole fraction solubility was recorded in water at 283.15 K; and the maximum one, in neat organic solvent at 323.15 K. The generated equilibrium solubility was satisfactorily described by two models, modified van’t Hoff-Jouyban–Acree and Jouyban–Acree, with the relative average deviations (%) of no more than 6.08. Good prediction results of extend Hildebrand solubility approach (relative average deviations (2) in ethyl acetate (1) + ethanol (2) solutions with ethyl acetate-rich compositions, and by water (2) solvent in aqueous blends with rich water compositions.

The development of inexpensive carbon fiber precursors is necessary to meet the future demands of carbon fibers. This work shows how asphaltenes, which are obtained as a by-product in bitumen production, can play an important role as such inexpensive carbon fiber precursors. To synthesize carbon fibers from asphaltene, stabilization by means of oxidizing acids (HNO3 and H2SO4) was developed. Stabilization could not be achieved by a non-oxidizing acid (HCl). The reactions leading to fiber stabilization was investigated for nitric acid treatment, which led to oxidation and the incorporation of nitro-groups. Further thermal treatment caused an increase in C/H ratio that was related to decomposition of nitro-groups, which facilitated air oxidation and other reactions leading to the loss of volatile hydrogen-rich products, such as light hydrocarbons. Additionally, the influence of the acid concentration during treatment on fiber properties, such as fiber diameter, composition, tensile strength and elastic modulus, has been examined. The application of the acid treatment leads to carbon fibers with good tensile properties, with a tensile strength and elastic modulus of 811 MPa and 32.7 GPa, respectively. The overall yield of carbon fibers is 37 – 38 wt.%.

Electrochemical carbon dioxide reduction offers a potential way to simultaneously mitigate carbon emission and produce value-added carbonaceous fuels and feedstock. This work proposes a facile method of O2 plasma bombardment to obtain efficient Au electrodes for selectively CO2 reduction. A sustainable setup assisted by solar energy is used to realize green utilization of CO2, with Fe2O3 photoanode for voltage compensation and Si solar cell for external bias. The O2 plasma treatment of Au results in formation of grain boundaries via fast surface reconstruction. The Au film with higher density of grain boundary possesses higher electrochemical active surface area, lower surface work function, and faster charge transfer through Au/electrolyte interface, which can facilitate the CO2 reduction. Compared with the as-deposited Au film, the O2 plasma treated Au film displays a lower overpotential and enhanced CO2-to-CO conversion performance. Faradic efficiency of 88.7% towards CO is achieved over plasma treated Au film.

Whereas bubble growth out of gas-oversatured solutions has been quite well understood, including the formation and stability of surface nanobubbles, this is not the case for bubbles forming on catalytic surfaces due to catalytic reactions, though it has important implications for gas evolution reactions and self-propulsion of micro/nanomotors fueled by bubble release. In this work we have filled this gap by experimentally and theoretically examining the growth and detachment dynamics of oxygen bubbles from hydrogen peroxide decomposition catalyzed by gold. We measured the bubble radius R(t) as a function of time by confocal microscopy and find R(t) ∝ t1/2. This diffusive growth behavior demonstrates that the bubbles grow from an oxygen-oversaturated environment. For several consecutive bubbles detaching from the same position in a short period of time, a well-repeated growing behavior is obtained from which we conclude the absence of noticeable depletion effect of oxygen from previous bubbles or increasing oversaturation from the gas production. In contrast, for two bubbles far apart either in space or in time, substantial discrepancies in their growth rates are observed, which we attribute to the variation in the local gas oversaturation. The current results show that the dynamical evolution of bubbles is influenced by comprehensive effects combining chemical catalysis and physical mass transfer. Finally, we find that the size of the bubbles at the moment of detachment is determined by the balance between buoyancy and surface tension and by the detailed geometry at the bubble's contact line. (Chemical Equation Presented).

We report the self-organization of universal branching patterns of oil nanodroplets under the Ouzo effect [Vitale S, Katz J (2003) Langmuir 19:4105–4110]—a phenomenon in which spontaneous droplet formation occurs upon dilution of an organic solution of oil with water. The mixing of the organic and aqueous phases is confined under a quasi-2D geometry. In a manner analogous to the ramification of ground stream networks [Devauchelle O, Petroff AP, Seybold HF, Rothman DH (2012) Proc Natl Acad Sci USA 109: 20832–20836 and Cohen Y, et al. (2015) Proc Natl Acad Sci USA 112:14132–14137] but on a scale 10 orders of magnitude smaller, the angles between the droplet branches are seen to exhibit remarkable universality, with a value around 74° ± 2°, independent of the various control parameters of the process. Numerical simulations reveal that these nanodroplet branching patterns are governed by the interplay between the local concentration gradient, diffusion, and collective interactions. We further demonstrate the ability of the local concentration gradient to drive autonomous motion of colloidal particles in the highly confined space, and the possibility of using the nucleated nanodroplets for nanoextraction of a hydrophobic solute. The understanding obtained from this work provides a basis for quantitatively understanding the complex dynamical aspects associated with the Ouzo effect. We expect that this will facilitate improved control in nanodroplet formation for many applications, spanning from the preparation of pharmaceutical polymeric carriers, to the formulation of cosmetics and insecticides, to the fabrication of nanostructured materials, to the concentration and separation of trace analytes in liquid–liquid microextraction.

Biologically inert gases play important roles in the biological functionality of proteins. However, researchers lack a full understanding of the effects of these gases since they are very chemically stable only weakly absorbed by biological tissues. By combining X-ray fluorescence, particle sizing and molecular dynamics (MD) simulations, this work shows that the aggregation of these inert gases near the hydrophobic active cavity of pepsin should lead to protein deactivation. Micro X-ray fluorescence spectra show that a pepsin solution can contain a high concentration of Xe or Kr after gassing, and that the gas concentrations decrease quickly with degassing time. Biological activity experiments indicate a reversible deactivation of the protein during this gassing and degassing. Meanwhile, the nanoparticle size measurements reveal a higher number of “nanoparticles” in gas-containing pepsin solution, also supporting the possible interaction between inert gases and the protein. Further, MD simulations indicate that gas molecules can aggregate into a tiny bubble shape near the hydrophobic active cavity of pepsin, suggesting a mechanism for reducing their biological function.

Four separation methods of antimicrobial substances produced by CMN1308 (Bacillus amyloliquefaciens) were evaluated and selected according to number of antimicrobial substances and its activity in vitro. The results showed that extraction by acid precipitation of the fermentation supernatant of CMN1308 was the best with a diameter of inhibition zone of pathogen fungi P. expansum of 12.3 mm in a laboratory bioassay. Applying a silica thin layer chromatography (TLC), SDS-PAGE and other separation technologies we isolate antimicrobial substances, and the separated band were cut off for mass spectrometry analysis. The TLC of crude extract of CMN1308 show a topical band corresponding with the surfactin standard (Rf value =0.75), proved that the strain CMN1308 can produce this surface active compound. The mycoprotein extracted from CMN1308 was separated by Tricine-SDS-PAGE modified with the addition of urea in the separation gel. After mass spectrometric analysis and protein characterization, the isolated mycoprotein showed a maximum ion peak at M/Z of 2679 and molecular weight of 29.5 kDa, matching with protein flagellin. The extracellular antimicrobial protein of strain CMN1308 display four bands after urea-Tricine-SDS-PAGE, but after mass spectrometry analysis only two bands were identified. Band “A” with a maximum ion peak at M/Z of 1926 and molecular weight of 49.8 kDa, aligned with NCBI database, matching with DLDH (dihydrolipoamide dehydrogenase enzyme). Band “D” show the maximum ion peak at M/Z of 2936 and molecular weight of 22.4 kD, matching with a chitin binding protein. Thus, the strain CMN1308 has the potential to be developed as a commercial biological control agent for chestnut common pathogenic fungi.

Recently, solvent exchange has been demonstrated as a simple solution-based approach for the controlled formation of surface nanodroplets over large areas. The as-formed surface nanodroplets provide new opportunities for a wide range of droplet-based applications. Herein, it is demonstrated that surface nanodroplets can be used as versatile structural templates for the fabrication of functional surfaces with tailored wettability and morphology. Guided by the microstructural and wetting properties of desert beetle's back and cactus spine, two types of functional surfaces have been prepared. The first biomimetic surface of desert beetle's back, with hydrophilic lumps on a hydrophobic background, was obtained by independent selective surface modification of polymerized surface nanodroplets and the background surface. The second surface, with anisotropic wetting microstructures, was fabricated by controlled deposition of droplets on the rim of polymer lenses. The results showed systematic improvement of wettability and efficiency of water collection by using the as-prepared biomimetic surfaces, compared with substrates without the designed microstructures. This work demonstrates surface nanodroplets as a new type of template in the design and preparation of functional surfaces with controlled wettability and morphology.

In the process of solvent exchange, oil droplets nucleate and grow on a solid substrate in response to the oversaturation generated through the displacement of a good oil solvent by a poor one. The mean size of the droplets depends on flow rate, flow geometry and solution conditions. In this work, we investigate the surface coverage of the droplets and the correlation between the base area of the droplets and of the bare zone surrounding the droplets for various flow and solution conditions during the solvent exchange. The surface coverage increases with the increase in the flow rate, channel height and the oil concentration, and reaches a plateau between 35% and 50%. The spatial correlation is analysed with the help of the radial distribution function g(r) and a Voronoi tessellation. When the surface coverage reaches [similar]25-30%, the number density of the droplets starts to drop, reflecting the mutual interaction and merging of the droplets. With further decrease in the droplet spacing and increase in surface coverage, the Voronoi analysis shows that the base area of the droplets increases linearly with the area size of the depleted zone. The collective interaction in the growth of surface nanodroplets is universal, independent of the specific conditions that control the droplet growth.

Constructing controllable liquid patterns with high resolution and accuracy is of great importance in droplet depositions for a range of applications. Simple surface chemical micropatterns have been popularly used to regulate the shape of liquid droplets and the final structure of deposited materials. In this work, we study the morphological evolution of a dissolving femtoliter droplet pinned on multiple microdomains. On the basis of minimization of interfacial energy, the numerical simulations predict various symmetric droplet profiles in equilibrium at different liquid volumes. However, our experimental results show both symmetric and asymmetric shapes of droplets due to contact line pinning and symmetry breaking during droplet dissolution. Upon slow volume reduction, the deposited microdroplet arrays on one single type of simple surface prepatterns spontaneously morphed into a series of complex regular 3D shapes. The findings in this work offer insights into design and prepararion of the rich and complex morphology of liquid patterns via simple surface premicropatterns.

An electrochemiluminescence (ECL) sensor based on a poly(luminol–benzidine sulfate) electrode has been fabricated for dopamine detection. Different concentrations of luminol and benzidine sulfate with a constant ratio of 2 : 3 are used as precursors to synthesize poly(luminol–benzidine sulfate) by cyclic voltammetry. Tyramine oxidase is immobilized onto the surface of the resultant poly(luminol–benzidine sulfate) film so as to oxidize dopamine and produce H2O2 for ECL detection. The ECL signal increases linearly with the concentration of dopamine in the range of 1–20 nM with the optimized electrode. The obtained biosensor exhibits a detection limit of 0.5 nM. It shows almost no response to the excess amount of interferents like ascorbic acid and uric acid with a 100-fold concentration of dopamine. Therefore, this work may provide a promising sensor with high sensitivity and selectivity for dopamine detection.

Toroidal microstructures of nanocolloidal assemblies promise important applications ranging from sensing, catalysis, drug delivery, and separation. In this work, we will first investigate the rich dissolution dynamics of a droplet comprising a nanoparticle suspension in a binary solution, and then show that the dissolution dynamics can be a potential approach to assembling a wide range of colloids with microtoroids. As the sessile droplet dissolves in the binary solution of miscible and immiscible solvents, two simultaneous effects are observed: if the dissolution rate is sufficiently high under large concentrations of the cosolvent in the surrounding solution, a strong plume emanates from the droplet pole as a consequence of a body force (i.e. the Korteweg force) driven by the chemical potential gradient between the water in the droplet and in the surrounding phase. Concurrently, the convection drives internal recirculation flow dynamics, leading to the inversion of the droplet curvature such that its initially spherical shape gradually contracts to evolve into a toroidal structure. We further demonstrate that the dissolution of a suspension droplet is an approach to assemble nanoparticles into toroidal microstructures. The resultant toroidal shapes are extrinsically governed by the composition and the geometrical confinement of the surrounding solution phase.

Microlens arrays are key elements for light management in optoelectronic devices. The recent advancement in the wearable intelligent electronics has driven the development of flexible microlenses. In this work, we show a controllable and scalable surface-droplet-based strategy to create unconventional flexible polymer microlens arrays. The technique is underpinned by the morphological transition of femtoliter liquid on the surface of a microlens surrounded by a planar area. We found that the droplet liquid wetted the rim of the microlens first and gradually moved upward to the microlens surface with an increase in the liquid volume. The morphology evolution of the droplet is in good agreement with the predication from our simulations based on the interfacial energy minimization under the condition of the pinned boundary. The shape of the droplet on the microlens is well controlled by the droplet volume, aspect ratio of the microlens, and the interfacial energy of the droplets on the microlens. As a result, the obtained structures of one microlens partially covered by a droplet can be produced in arrays over a large scale, serving as templates for fabricating transparent polymer double microlens arrays for improved light emission from the optoelectronic device.

Lens-shaped microstructures on solid surfaces are important for a variety of applications, such as enhanced water harvesting, super-resolution imaging, and antireflection. Here the formation of polymeric microlenses with tunable contact angles based on an Ouzo effect is reported. In this process, water is added into a binary toluene/ethanol solution in contact with a polystyrene (PS) thin film. The dilution by water leads to spontaneous formation of toluene microdroplets due to the reduced solubility of toluene in the ternary liquid mixture (i.e., the Ouzo effect). PS in the thin film is dissolved into the toluene droplets. However, the droplets containing PS and toluene are not stable against dissolution, and eventually toluene dissolved into the surrounding ternary mixture. PS in the droplets is left on the substrate, forming microlenses on the supporting glass substrate. The size and density of PS lenses are influenced by PS film thickness and toluene concentration in the surrounding liquid. The contact angle of PS microlens could be varied through a thermal reshaping method. As demonstration for potential applications, the results show that the as-prepared microlenses can improve the spatial resolution of a standard upright optical microscope.

Microdents fabricated on solid substrates have numerous applications, such as containers for cell growth, reactors for chemical reactions, and nucleation sites for growing photonic crystals. In this study, a new method is developed to fabricate microdents on polystyrene (PS) film deposited on a solid surface. The process relied on Ouzo effect in a ternary solution consisting of three solvents exhibiting different volatilities. In the ternary solution, precursor water droplets are first nucleated when a good solvent of water evaporated. The nucleated water droplets then act as templates for microdent formation during PS film deposition. After water droplets eventually evaporates, microdents are generated on the PS film. The detailed process of microdent formation is experimentally revealed. By controlling the nucleation of water droplets and PS concentration, the lateral size and the depth of microdents are systematically tuned. Moreover, it is demonstrated that the microdent decorated films obtained with the proposed method can be used to fabricate lubricating surfaces, which exhibit a low contact angle hysteresis of 2°.