Catalytic confinement effects in nanochannels: from biological synthesis to chemical engineering.

Catalytic reactions within nanochannels are of significant importance in disclosing the mechanisms of catalytic confinement effects and developing novel reaction systems for scientific and industrial demands. Interestingly, catalytic confinement effects exist in both biological and artificial nanochannels, which enhance the reaction performance of various chemical reactions. In this minireview, we investigate the recent advances on catalytic confinement effects in terms of the reactants, reaction processes, catalysts, and products in nanochannels. A systematic discussion of catalytic confinement effects associated with biological synthesis in bio-nanochannels and catalytic reactions in artificial nanochannels in chemical engineering is presented. Furthermore, we summarize the properties of reactions both in nature and chemical engineering and provide a brief overlook of this research field.

Ultrahigh efficient emulsification with drag-reducing liquid gating interfacial behavior.

Emulsification is a crucial technique for mixing immiscible liquids into droplets in numerous areas ranging from food to medicine to chemical synthesis. Commercial emulsification methods are promising for high production, but suffer from high energy input. Here, we report a very simple and scalable emulsification method that employs the drag-reducing liquid gating structure to create a smooth liquid-liquid interface for the reduction of resistance and tunable generation of droplets with good uniformity. Theoretical modeling and experimental results demonstrate that our method exhibits ultrahigh efficiency, which can reach up to more than 4 orders of magnitude greater energy-saving compared to commercial methods. For temperature-sensitive biological components, such as enzymes, proteins, and bacteria, it can offer a comfortable environment to avoid exposure to high temperatures during emulsifying, and the interface also enables the suppression of fouling. This unique drag-reducing liquid gating interfacial emulsification mechanism promotes the efficiency of droplet generation and provides fresh insight into the innovation of emulsifications that can be applied in many fields, including the food industry, the daily chemical industry, biomedicine, material fabrication, the petrochemical industry, and beyond.

Bioinspired Photo-Responsive Liquid Gating Membrane.

Stomata in the plant leaves are channels for gas exchange between the plants and the atmosphere. The gas exchange rate can be regulated by adjusting the opening and closing of stoma under the external stimuli, which plays a vital role in plant survival. Under visible light irradiation, the stomata open for gas exchange with the surroundings, while under intense UV light irradiation, the stomata close to prevent the moisture loss of plants from excessive transpiration. Inspired by this stomatal self-protection behavior, we have constructed a bioinspired photo-responsive liquid gating membrane (BPRLGM) through infusing the photo-responsive gating liquid obtained by dissolving the azobenzene-based photo-responsive surfactant molecules (AzoC8F15) in N,N-Dimethylacetamide (DMAC) into nylon porous substrate, which can reversibly switch the open/closed states under different photo-stimuli. Theoretical analysis and experimental data have demonstrated that the reversible photoisomerization of azobenzene-based surfactant molecules induces a change in surface tension of the photo-responsive gating liquid, which eventually results in the reversible variation of substantial critical pressure for gas through BPRLGM under alternating UV (PCritical (off)) and visible (PCritical (on)) light irradiations. Therefore, driven by a pressure difference ΔP between PCritical (on) and PCritical (off), the reversible switches on the open/closed states of this photo-responsive liquid gating membrane can be realized under photo-stimuli. This bioinspired membrane with switchable open/closed liquid gating performance under photo-stimuli has the opportunity to be used in the precise and contactless control of microfluidics.

Host-guest liquid gating mechanism with specific recognition interface behavior for universal quantitative chemical detection.

Universal visual quantitative chemical detection technology has emerged as an increasingly crucial tool for convenient testing with immediate results in the fields of environmental assessment, homeland security, clinical drug testing and health care, particularly in resource-limited settings. Here, we show a host-guest liquid gating mechanism to translate molecular interface recognition behavior into visually quantifiable detection signals. Quantitative chemical detection is achieved, which has obvious advantages for constructing a portable, affordable, on-site sensing platform to enable the visual quantitative testing of target molecules without optical/electrical equipment. Experiments and theoretical calculations confirm the specificity and scalability of the system. This mechanism can also be tailored by the rational design of host-guest complexes to quantitatively and visually detect various molecules. With the advantages of versatility and freedom from additional equipment, this detection mechanism has the potential to revolutionize environmental monitoring, food safety analysis, clinical drug testing, and more.

Carbon Dioxide Chemically Responsive Switchable Gas Valves with Protonation-Induced Liquid Gating Self-Adaptive Systems.

Carbon dioxide (CO2 ) capture and storage technologies are promising to limit CO2 emission from anthropogenic activities, to achieve carbon neutrality goals. CO2 capture requires one to separate CO2 from other gases, and therefore a gas flow system that exhibits discernible gating behaviors for CO2 would be very useful. Here we propose a self-adaptive CO2 gas valve composed of chemically responsive liquid gating systems. The transmembrane critical pressures of the liquid gate vary upon the presence of CO2 , due to the superamphiphiles assembled by poly(propylene glycol) bis(2-aminopropyl ether) and oleic acid in gating liquids that are protonated specifically by CO2 . It is shown that the valve can perform self-adaptive regulation for specific gases and different concentrations of CO2 . This protonation-induced liquid gating mechanism opens a potential platform for applications of CO2 separators, detectors, sensors and beyond.

Comparative Efficacy and Safety of Four Different Spontaneous Breathing Trials for Weaning From Mechanical Ventilation: A Systematic Review and Network Meta-Analysis.

Background: Spontaneous breathing trial (SBT) has been used to predict the optimal time of weaning from ventilator. However, it remains controversial which trial should be preferentially selected. We aimed to compare and rank four common SBT modes including automatic tube compensation (ATC), pressure support ventilation (PSV), continuous positive airway pressure (CPAP), and T-piece among critically ill patients receiving mechanical ventilation (MV). Methods: We searched PubMed, EMBASE, and the Cochrane Central Register of Controlled Trials (CENTRAL) to identify studies that investigated the comparative efficacy and safety of at least two SBT strategies among critically ill patients up to May 17, 2020. We estimated the surface under the cumulative ranking curve (SUCRA) to rank SBT techniques, and determined the certainty of evidence using the Grading of Recommendations Assessment, Development and Evaluation method. Primary outcome was weaning success. Secondary outcomes were reintubation, SBT success, duration of acute care, and intensive care unit (ICU) mortality. Statistical analysis was conducted by using RevMan 5.4, Stata, and R software. Results: We enrolled 24 trials finally. Extubation success rate was significantly higher in ATC than that in T-piece (OR, 0.28; 95% CI, 0.13-0.64) or PSV (OR, 0.53; 95% CI, 0.32-0.88). For SBT success, ATC was better than other SBT techniques, with a pooled OR ranging from 0.17 to 0.42. For reintubation rate, CPAP was worse than T-piece (OR, 2.76; 95% CI, 1.08 to 7.06). No significant difference was detected between SBT modes for the length of stay in ICU or long-term weaning unit (LWU). Similar result was also found for ICU mortality between PSV and T-piece. Majority direct results were confirmed by network meta-analysis. Besides, ATC ranks at the first, first, and fourth place with a SUCRA of 91.7, 99.7, and 39.9%, respectively in increasing weaning success and SBT success and in prolonging ICU or LWU length of stay among four SBT strategies. The confidences in evidences were rated as low for most comparisons. Conclusion: ATC seems to be the optimal choice of predicting successful weaning from ventilator among critically ill patients. However, randomized controlled trials (RCTs) with high quality are needed to further establish these findings.

Effect of universal adhesive and silane pretreatment on bond durability of metal brackets to dental glass ceramics.

This study aimed to investigate the effect of universal adhesive and silane pretreatment on the bond durability of metal brackets to dental glass ceramics. Eighty lithium disilicate glass ceramic specimens were randomly assigned to one of four groups (n = 20) defined by the pretreatment and adhesive used: (i) Adper Single Bond 2; (ii) silane + Adper Single Bond 2; (iii) Single Bond Universal; and (iv) silane +Single Bond Universal. Maxillary central incisor metal brackets were bonded on the ceramic surfaces with resin composite. A shear bond strength test was conducted after 24 h of water storage and after 10,000 thermocycles. Adhesive remnant index scoring and field-emission scanning electron microscopy were performed to determine adhesives remaining on the ceramic surfaces and the ceramic ultrastructure following bracket debonding, respectively. After 10,000 thermocycles, specimens treated with Single Bond Universal preserved an appropriate bond strength between brackets and glass ceramics and showed minimum ceramic surface damage following bracket debonding, which was not the case in the other three groups. The application of a silane-containing universal adhesive without silane pretreatment achieves adequate durability of the bond of metal brackets to dental glass ceramics and allows safe debonding, which may aid in optimizing the effectiveness for orthodontic treatment.

A simple and effective strategy to enhance the stability and solid-liquid interfacial interaction of an emulsion by the interfacial dilational rheological properties.

The development of an emulsion is an important challenge in many fields, such as agrochemicals, pharmaceutics, paints, cosmetics, inkjet printing, and food science. However, the traditional strategies that refer to the empirical value and complex secondary additives cannot reflect the influence of the structure, content, compound, and adsorption of emulsifiers. Here, we propose a simple and effective strategy to develop the emulsion, wherein the emulsifiers are chosen based on the dilational rheological properties of the interfacial films at the molecular level. The dilational rheological properties of polyoxyethylene (80) castor oil (EL-80), sorbitan monostearate (Span 60), and their emulsions were explored by the oscillating drop method. Based on the dilational rheological properties, the emulsions were prepared by the phase inversion emulsification technique. The results showed that the emulsion was stable and realized effective solid-liquid interfacial interaction, which was attributed to the large dilational modulus (intermolecular interaction) at the oil/water interface and loss modulus (molecular diffusion exchange) at the air/water interface. These factors reduced the Ostwald ripening and coalescence, and finally increased the spreading diameter. Additionally, the prochloraz 25% emulsion in water (EW) and difenoconazole 20% EW were developed to verify the feasibility of the strategy. Therefore, this research advances the understanding of an emulsion by interfacial dilational rheological properties, which can provide a simple and effective strategy to develop a stable emulsion and achieve an effective solid-liquid interfacial interaction of the emulsion.

Development of Epigallocatechin-3-gallate-Encapsulated Nanohydroxyapatite/Mesoporous Silica for Therapeutic Management of Dentin Surface.

In dental clinic, unsatisfactory management of the dentin surface after dentin exposure often leads to the occurrence of dentin hypersensitivity and caries. Current approaches can occlude the tubules on the dentin surface to relieve dentin hypersensitivity; however, the blocked tubules are generally weak in combating daily tooth erosion and abrasion. Moreover, cariogenic bacteria, such as Streptococcus mutans, produce biofilm on the dentin surface, causing caries and compromising the tubules' sealing efficacy. To overcome this problem, the present study focused on establishing a versatile biomaterial, epigallocatechin-3-gallate-encapsulated nanohydroxyapatite/mesoporous silica nanoparticle (EGCG@nHAp@MSN), for therapeutic management of the dentin surface. The effectiveness of the biomaterial on dentinal tubule occlusion, including resistances against acid and abrasion, was evaluated by field-emission scanning electron microscopy (FESEM) and dentin permeability measurement. The inhibitory capability of the biomaterial on S. mutans biofilm formation was investigated by confocal laser scanning microscopy (CLSM), 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, colony forming units (CFU) counts, and FESEM. Results demonstrated for the first time that the use of EGCG@nHAp@MSN on the dentin surface was capable of effectively occluding dentinal tubules, reducing dentin permeability, and achieving favorable acid- and abrasion-resistant stability. Furthermore, EGCG@nHAp@MSN held the capability to continuously release EGCG, Ca, and P, and significantly inhibit the formation and growth of S. mutans biofilm on the dentin surface. Thus, the development of EGCG@nHAp@MSN bridges the gap between multifunctional concept and dental clinical practice and is promising in providing dentists a therapeutic strategy for the management of the dentin surface to counter dentin hypersensitivity and caries.

The wetting behavior of aqueous surfactant solutions on wheat (Triticum aestivum) leaf surfaces.

In this research the wetting behavior of agro-surfactant solutions (Triton X-100, SDS, DTAB) on wheat leaf surfaces have been investigated based on the surface free energy, surface tension, and the contact angle. The results show that the contact angle of those surfactant solutions keeps constant with low adsorption at interfaces below 1 × 10-5 mol L-1. With the increase in concentration, the contact angles of Triton X-100 decrease sharply because the adsorption of molecules at solid-liquid interfaces (ΓSL') is several times greater than that at liquid-air interfaces (ΓLV). With regards to SDS and DTAB, the contact angle also decreases but is even larger than 90° above the CMC, while the ratio of ΓSL' to ΓLV is about 1.20, demonstrating that the Gibbs surface excess is related to the structure of surfactant molecules. Obviously, besides the properties of wheat leaf surfaces and surfactant solutions, the wetting behavior mainly depends on their noncovalent interactions. Among these, the hydrophobic interaction is the main force promoting molecules to adsorb on the surface, with the assistance of the Lifshitz-van der Waals interactions and the electrostatic interactions. According to the mechanism of their wetting behavior on plant surfaces, the recipe of pesticide formulation can be adjusted with better wettability to reduce its loss, consequently improving pesticide utilization and decreasing environmental contamination.

Ferromagnetic and Photocatalytic Properties of Layered Perovskite LaBaCo2O6 Nanostructures.

Cationic ordered layered tetragonal perovskite phase LaBaCo2O6 (LBCO) nanomaterials with irregular shape, and an average diameter of about 100 nm were successfully prepared. A precursor material was annealed in an argon atmosphere at 1100 °C for 48 hours, and then heat treated in an oxygen atmosphere pressure at 800 °C for 12 hours. The resulting LBCO nanomaterials show ferromagnetic transition at about 175 K without any structural changes. They show metallic behavior at below 140 K, and adopt the behavior of soft ferromagnetic materials at 80 K. Cationic ordered LBCO nanomaterials display photocatalytic activities, as they successfully degrade MB solutions under both UV irradiation and visible light. The B-site cations act as the active center, and are located in the centre of BO6 octahedron units. The various valence states of Co ions in LBCO could contribute to the enhancement of photocatalytic activies.

A novel application of nanohydroxyapatite/mesoporous silica biocomposite on treating dentin hypersensitivity: An in vitro study.

OBJECTIVES: To fabricate a nanohydroxyapatite/mesoporous silica nanoparticle (nHAp@MSN) biocomposite and investigate its effectiveness on dentinal tubule occlusion, acid-resistant stability, and microtensile bond strength (MTBS). METHODS: The nHAp@MSN biocomposite was synthesized and characterized by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, N2 adsorption-desorption isotherms, field-emission scanning electron microscopy (FESEM), and high-resolution transmission electron microscopy (HRTEM). Thirty-two simulated sensitive dentin discs were prepared and randomly divided into four groups according to the following treatments (n=8 each): Group 1, no treatment; Group 2, NovaMin, 15 s×2; Group 3, MSN, 15 s×2; Group 4, nHAp@MSN, 15 s×2. Then, four discs per group were post-treated with 6wt.% citric acid challenge to test their acid-resistant stability. The effects on dentinal tubule occlusion were observed by FESEM. A self-etch adhesive (G-Bond) was applied to evaluate the MTBS. The cytotoxicity was detected using the Cell Counting Kit-8 (CCK-8) assay. RESULTS: Results revealed that the nHAp@MSN biocomposite was successfully fabricated. nHAp@MSN could effectively occlude the dentinal tubules, and the intratubular crystals were tightly associated with the tubular wall. After citric acid attack, nHAp@MSN exhibited the highest acid-resistant stability among the four groups. Moreover, no significant difference in MTBS was noted among the four groups (P>0.05). CCK-8 assay identified that nHAp@MSN induced no more than 20% cell death even at the highest concentration of 640µg/mL. CONCLUSIONS: The application of the nHAp@MSN biocomposite resulted in efficient dentinal tubule occlusion, acid-resistant stability, and did not compromise immediate bond strength between dentin and self-etch adhesive system. CLINICAL SIGNIFICANCE: The nHAp@MSN biocomposite indicates enormous potential as a new strategy for relieving dentin hypersensitivity.

Expression of Pannexin3 in human odontoblast-like cells and its hemichannel function in mediating ATP release.

OBJECTIVE: The aim of this study is to investigate the expression of pannexin3 (Panx3) in human odontoblast-like cells (hOBs) and its hemichannel function in mediating ATP release. METHODS: RT-PCR and immunofluorescence analysis were used to detect the expression of pannexins (Panxs) in human dental pulp tissue and cultured cells. To determine the role of Panx3 in ATP release, hOBs were infected with Panx3-overexpression lentivirus, Panx3-shRNA lentivirus or control lentivirus and then stimulated with cold buffer. Intracellular ATP was monitored using quinacrine, and then semi-quantitatively analyzed. In the meantime, the ATP release was quantitatively analyzed using the bioluminescence method when the cells were exposed to cold stimulus. RESULTS: Panx3 mRNA and protein were found in dental pulp tissue and cultured cells. Upon cold stimulus, intracellular ATP was released into the extracellular space. Overexpression of Panx3 accelerated ATP release, whereas inhibition of Panx3 suppressed this process. CONCLUSION: Panx3 hemichannel is expressed in human odontoblast-like cells and mediates ATP release into the extracellular space.

Highly Responsive Room-Temperature Hydrogen Sensing of α-MoO3 Nanoribbon Membranes.

[001]-Oriented α-MoO3 nanoribbons were synthesized via hydrothermal method at temperature from 120 to 200 °C and following assembled a membrane on interdigital electrodes to form sensors. The sensitivity, response speed, and recovery speed of the sensor improve with the increasing hydrothermal temperature. Among them, the sample obtained at 200 °C exhibits a room-temperature response time of 14.1 s toward 1000 ppm of H2. The nanoribbons also show good selectivity against CO, ethanol, and acetone, as well as high sensitivity to H2 with a concentration as low as 500 ppb. The hydrogen sensing behavior is dependent on the redox reaction between the H2 and chemisorbed oxygen species. Higher hydrothermal temperature creates larger specific surface area and higher Mo(5+) content, leading to increased chemisorbed oxygen species on the nanoribbon surface.

Equilibrium and dynamic interfacial properties of protein/ionic-liquid-type surfactant solutions at the decane/water interface.

The interfacial behavior of ß-casein and lysozyme solutions has been investigated in the presence of an ionic liquid-type imidazolium surfactant ([C16mim]Br) at the decane/water interface. The dynamic dilational properties of the protein/surfactant solutions are investigated by the oscillating drop method and interfacial tension relaxation method. The interfacial tension isotherms for the mixed adsorption layers indicate that the increased addition of [C16mim]Br to a pure protein changes the properties of the complex formed at the decane/water interface. Whereas the interfacial tension data of the protein/surfactant mixed layers do not clearly show differences with changing bulk composition, the dilational rheology provides undoubted evidence that the structure and, in particular, the dynamics of the adsorbed layers depend on the bulk surfactant concentration. The experiment data for ß-casein/[C16mim]Br solutions indicate that at higher bulk [C16mim]Br concentrations, ß-casein in the interfacial layer is subject to conformational changes, where it gives space to [C16mim]Br molecules in the form of coadsorb rather than replacement; in contrast, in lysozyme/[C16mim]Br solutions some lysozyme molecules desorb from the interface due to the competitive adsorption of free [C16mim]Br molecules. Experimental results related to the interfacial dilational properties of the protein/surfactant solutions show that the dilational modulus turns out to be more sensitive to the conformation of protein/surfactant mixture at the liquid interface than the interfacial tension.

Impact of ionic liquid-type imidazolium surfactant addition on dynamic properties of BSA adsorption layers at different pH.

The dynamic interfacial properties of mixed solutions of bovine serum albumin (BSA) and the ionic liquid-type imidazolium surfactant ([C16mim]Br) were measured as a function of the interface age, surfactant concentration and solution pH. Three BSA conformers were investigated: the normal N form as well as the fast F and aged A forms, corresponding to the different solution pH, respectively. The interfacial tension and the interfacial dilational elasticity isotherms for the mixed adsorption layers indicate that the addition of [C16mim]Br to the different structures of BSA isomers influences the properties of the adsorption layer at the decane/water interface. The addition of [C16mim]Br does not influence the structure of the protein at pH below the isoelectric point of BSA, but at higher solution pH, the addition of surfactants significantly influences the dynamic interfacial properties of BSA solutions due to the electrostatic interaction between the components.

Effects of the application sequence of calcium-containing desensitising pastes during etch-and-rinse adhesive restoration.

OBJECTIVES: To evaluate the effects of different application sequence of calcium-containing desensitising pastes on bonding effectiveness and tubule occlusion during etch-and-rinse (E&R) adhesive restoration. METHODS: Seventy molars were sectioned parallel to the occlusal plane, polished and randomly divided into seven groups (n=10). Group 1 was etched with 35% phosphoric acid for 15s. Groups 2-4 were treated with different calcium-containing desensitisers, including an arginine-calcium carbonate (Arg-CaCO3)-containing paste, a casein phosphopeptide-amorphous calcium phosphate (CPP-ACP)-containing paste and a calcium-sodium phosphosilicate (Novamin)-containing paste, respectively. Afterward, these groups were etched with 35% phosphoric acid for 15s. Groups 5-7 were initially etched and then treated with Arg-CaCO3-, CPP-ACP- and Novamin-containing desensitisers, respectively. In each group, samples were equally distributed into two subgroups (n=5) to bond with either a two-step E&R adhesive Adper SingleBond 2 (SB) or a three-step E&R adhesive Adper ScotchBond Multi-Purpose (SBMP). The microtensile bond strengths (MTBS) were tested and fracture modes were analyzed by stereomicroscopy and field-emission scanning electron microscopy (FESEM). Eight additional dentine disks were prepared to evaluate tubule occlusion prior to bonding using FESEM. RESULTS: The application sequence of calcium-containing desensitising pastes did not significantly affect MTBS irrespective of two-step SB (P>0.05) or three-step SBMP E&R adhesives (P>0.05). Effective dentinal tubule occlusion was observed in the mode of etching-desensitising. CONCLUSIONS: Applying calcium-containing desensitisers (particularly Arg-CaCO3- and Novamin-based) after etching during E&R adhesive restoration could achieve effective tubule occlusion without affecting the bonding strength.

[Combination of dispersive liquid-liquid microextraction based on ionic liquid and pre-column fluorescence derivatization-high performance liquid chromatography for determination of eight sulfonamides in water samples].

Dispersive liquid-liquid microextraction based on ionic liquid coupled with high performance liquid chromatography (HPLC) and pre-column fluorescent derivatization method (IL-DLLME-HPLC-FL) was developed for the determination of eight sulfonamides (SAs). The influence of IL-DLLME parameters on extraction efficiency and the stability of derivatives of the eight SAs were investigated. The optimized experimental conditions were as follows: 40 µL [C6MIM][PF6] as extraction solvent, 0.1 mL acetone as dispersion solvents; water sample with 0% NaCl (pH 4) was extracted by dispersive liquid-liquid microextraction without ultrasonic-assistance and then derivatized for 6 h. Under the optimized experimental conditions, the results indicated that the eight sulfanilamides showed good linearities when their mass concentrations were in 0. 2-10 µg/L and 10-500 µg/L, and the linear correlation coefficients were no less than 0. 9989. The detection limits ranged from 0. 08 µg/L to 0. 5 µg/L (S/N=3). The proposed method was applied to the analysis of four water samples from different sources (tap water, lake water, Pearl River water and pond water). The relative recoveries of the SAs spiked in water samples were 87. 2% - 101. 4% with the relative standard deviations of 3. 7% - 6. 2% at three different concentration levels of 5, 50 and 200 µg/L. It is a convenient, environmental friendly method for the routine analysis of SAs in water samples.