Current antibacterial sprays face major limitations, including rapid evaporation, short-lived efficacy, skin irritation, and poor adhesion to surfaces, highlighting an urgent need for a durable and biocompatible alternative. To address these challenges, we developed a ZIF-8-based spray (ZNS-WO20) composed of ZIF-8 nanoparticles dispersed in 50% ethanol and 20% OTES. OTES acts as a dispersant and binder, enabling wash-resistant coatings on gauze and glass. ZIF-8 exhibits pH-responsive Zn2+ release, achieving nearly 100% killing of S. aureus, E. coli, and methicillin-resistant S. aureus (MRSA) at 160 μg/mL through intracellular reactive oxygen species (ROS) generation. The spray maintains >95% antibacterial efficacy against S. aureus after five washing cycles and seven days of outdoor exposure, and causes no dermal irritation in rats. This work fills the gap for a long-lasting, skin-friendly antibacterial spray, showing promise for healthcare disinfection and surface protection.

The synergistic effect of two commonly used thermodynamic gas hydrate inhibitors (THIs), methanol (MeOH) and monoethylene glycol (MEG), with a kinetic gas hydrate inhibitor (KHI), poly(ethylene oxide-co-vinylpyrrolidone) (PEO-co-VP), at the underinhibited conditions was investigated using synthetic natural gas and a 200 mL high-pressure cell. The investigated concentration range was 0.0-15.0 wt % for THIs and 0.1-1.0 wt % for PEO-co-VP. Both THIs showed a concentration-dependent synergistic effect on PEO-co-VP, which became more noticeable when the THI concentration was equal to or above 10.0 wt %. Stronger synergistic effects were demonstrated by MEG than by MeOH under the same conditions. A total inhibition of gas hydrate formation over 6000 min was yielded when 15.0 wt % MEG was used with 1.0 wt % PEO-co-VP. Quantitative analysis showed that during the course of gas hydrate formation, the KHI concentration in the liquid phase decreased with time when no MEG was used, confirming that the adsorption of KHI molecules onto the formed hydrates was the predominant inhibition mechanism. However, in the presence of MEG or MeOH, the KHI concentration in the liquid phase increased after the formation of hydrates, suggesting a totally different inhibition mechanism, which we speculate is a result of the improved solubility of PEO-co-VP in the aqueous phase due to its stronger molecular interactions with MEG and MeOH. Further investigations on the effect of subcooling demonstrated that the added THIs not only can improve the inhibition performance of the KHI but also could possibly improve its workable subcooling range. The findings in this work suggest that kinetic inhibitors can be used at high subcooling if an adequate concentration of MEG is applied at the same time.

This study aims to determine any synergistic effect on hydrate dispersion stability by combining under -inhibited monoethylene glycol (MEG) with synthetic surfactants such as anti-agglomerants (AA). Hydrate dispersion stability describes the tendency of hydrate particles to remain dispersed without agglomerat-ing in an oil-dominated system. The usage of under-inhibited MEG may result in hydrate agglomeration due to self-inhibited MEG that generates unconverted water during hydrate formation stage, contrary to the usage of AA which could improve stability of hydrate dispersion. Differential scanning calorimeter (DSC) was used to measure hydrate dispersion stability via integrated area of hydrate dissociation curves that reduces gradually during repeated hydrate formation-dissociation cycles. Unforseen improvement was recorded at MEG 1-3 wt% and synergistic improvement observed at AA 1 wt% with no further improvement at higher concentration. This reflects the presence of surfactants from natural and/or syn-thetic may prevent water droplets from coalescing and hydrate particles from aggregating.(c) 2023 Elsevier Ltd. All rights reserved.

The promotion of gas hydrate formation kinetics through mass transfer enhancement has been an important research topic, for which microparticles have been considered an effective method. In this work, carbon dioxide (CO2) and methane (CH4) hydrate formation kinetics in microparticles are investigated using "dry water" particles made of 3, 5 and 8-wt% silica. A modified shrinking-core model is established to study the CO2 and CH4 hydrates formation kinetics. It is the first model that integrates the effects of dissolved gas, the capillary effect of porous hydrate shell, and the volume change from water to hydrate. The experimental results reveal that "dry water" particles with 8-wt% silica has the highest normalized gas uptake due to their small particle size. The simulation results show an initial effective diffusion coefficient of 6.41-6.50 x 10(-)(14) m(2) s(-1) for CO2 and a slightly higher 6.83 x 10(-)(14) m(2) s(-1) for CH4 hydrate formation. The average effective diffusion coefficient of gas is higher in smaller particles. The water consumed through capillaries is more prominent in smaller particles, but it only accounts for less than 10% of water consumed at the hydrate-water interface. Furthermore, a decoupled heat transfer model was developed to quantify the effect of heat transfer in gas hydrate formation. The instantaneous temperature gradient in the hydrate shell is of a small magnitude of 10(-2) K m(-1), indicating that the impact of the heat transfer on hydrate formation kinetics is negligible. This work provides comprehensive insights into gas hydrate formation in microparticles and contributes as a theoretical basis for the improvement of gas hydrate kinetics through mass transfer enhancement.

In this study, Tween 80 was chosen as a kinetic promoter to study the effect of non-ionic surfactant on CO2 hydrate formation kinetics. The experiments were carried out in a thermostatic reactor using CO2-rich gas mixtures with Tween 80 (0–3000 ppm) in both clathrate hydrates and tetra-n-butyl ammonium bromide (TBAB) semiclathrate hydrates. Analysis of variance (ANOVA) was used to analyze the difference among experimental results, and a decision box was proposed to evaluate the performance of systems studied. The apparent improvement in the induction time, gas uptake yield, and gas separation performance were observed in 1000-ppm or 2000-ppm Tween 80 in semiclathrate hydrates. Increased pressure further improved the kinetic promotion effect of Tween 80. However, a higher concentration of 3000-ppm Tween 80 was found to result in an inhibition effect on CO2 uptake yield in semiclathrate hydrates, although the induction time remained short. Compared with common anionic and cationic surfactants, 2000-ppm Tween 80 showed the best CO2 separation performance from gas mixtures in semiclathrate hydrates. No inhibition effect was observed in clathrate hydrates with studied concentrations of Tween 80.

在500mL的高压反应釜中,实验研究了乙二醇(MEG)与动力学抑制剂PEO-co-VCap-1在细砂存在下对甲烷水合物再生成过程的协同抑制作用.实验过程中,控制MEG的质量分数范围为0～5％,PEO-co-VCap-1的质量分数范围为0～0.5％,形成4种的抑制剂配伍组合,进行了12组实验.实验结果表明,PEO-co-VCap-1在单独作用时,可以延缓水合物的成核阶段,但可能导致水合物在生长阶段短时间内大量生成的灾难性生长现象.其与MEG复配可在延缓水合物成核的同时,有效减少灾难性增长现象的出现,降低油气管输的堵管风险.当MEG质量分数为5％、PEO-co-VCap-1质量分数为0.5％时,协同抑制效应极为明显,可将甲烷水合物诱导期延长至2800min以上.MEG同PEO-co-VCap-1的协同抑制效果与提高温度的抑制作用相似.这一发现表明,如果在使用PEO-co-VCap-1的同时使用MEG等良好的增效剂,有助于动力学抑制剂用于更高的过冷度环境,为高效解决高过冷条件下油气生产中的水合物防控问题提供新的可能.

The carbon dioxide (CO2) hydrate formation kinetics in silica gel (SG) nanopores with the addition of sur-factants are studied both experimentally and numerically. SGs with pore sizes of 50 and 100 nm are used as frameworks for hydrate formation in pores. Sodium dodecyl sulfate (SDS) or dodecyltrimethylammo-nium chloride (DTAC) are used as kinetics promoters which can greatly enhance gas-water mass transfer. An advanced shrinking core model considering CO2 solubility, pore size, surfactants, and capillary effect is established. The results reveal that the reaction rate constant is increased in large pores or in the presence of surfactants, saving up to 49.3 % time to achieve the same amount of gas uptake in 100-nm SG with 500-ppm SDS. The effective diffusion coefficient controlled by a reduction factor drops dramatically due to the enlargement of the reduction factor in small pores and more surfactants, thus hindering the gas diffusion through the formed hydrate shell. The initial water consumed by capillary effect is more prominent in smaller pores and with the addition of surfactants. The initial proportion of water consumed by capillary effect to the total water consumption is only 1%-26.6% without surfactants, but can be up to 74.9% in 50-nm SGs with 500-ppm SDS. This proportion is overall higher in SDS systems than that in studied DTAC systems, but it is not obviously affected by surfactant concentrations. The higher proportion of water con-sumed by capillaries is speculated to be due to the more capillary tubes with larger radii formed initially in the presence of surfactants. The modeling strategies in this work can be applied to hydrate formation mechanisms in other porous materials. (C) 2022 Elsevier Ltd. All rights reserved.

Nerve injury often leads to severe biological dysfunctions, such as motor insufficiency and sensory impairment. Guided axonal growth and stem cell differentiation for functional restoration is central to nerve tissue repair after periphery nerve injury and trauma-induced spinal cord injury. Aligned biodegradable polymeric fibers by electrospinning not only possess high surface areas for cell attachment and migration, but also provide topological cues to guide the neurite outgrowth and stimulate the differentiation of stem cells. The incorporation of natural materials, neurotropic factors, drugs, and other signaling molecules further provides biological cues and a suitable microenvironment for neurite extension and nerve regeneration, which has shown significant advantages compared to the single material scaffolds. This chapter consists of a brief introduction on the electrospinning technology and the bioactive electrospun composites for neural tissue engineering applications. This is followed by an elaborated discussion on the materials suitable for peripheral nerve injury and spinal cord injury, respectively. Discussions about the synergistic effects of physical and biological cues of the electrospun composite scaffolds on the neural cells proliferation, neurite growth, glial cells migration, and regenerated nervous system functionalization, both in vitro and in vivo, are also included.

Tetra-n-butyl ammonium bromide (TBAB) is a commonly used promoter to moderate CO2 hydrate phase equilibrium. However, it decreases CO2 gas uptake. In this work, the effects of anionic surfactant sodium dodecyl sulfate (SDS) and cationic surfactant dodecyltrimethylammonium chloride (DTAC) on the kinetics of CO2-TBAB hydrate formation are investigated. Experiments in a batch reactor at the same initial pressure of CO2/N-2 gas mixtures are conducted in systems of 10-wt% TBAB and varied SDS concentrations of 0-1500 ppm and DTAC concentrations of 0-0.6 wt%. Induction time, normalized gas uptake, split fraction and separation factor are the metrics to study in this paper. The results show that the hydrate formation is most accelerated with the addition of SDS, and the best CO2 separation performance is achieved in the presence of DTAC. 10-wt%TBAB with 0.1-wt% DTAC is found to be the optimum recipe, and it leads to the same amount of CO2 uptake at 283.15 K as that in a pure water system at 276.45 K under the same initial pressure. CO2 uptake is also found to increase with a higher subcooling. Furthermore, the intensive uptake period of different systems is determined for practical applications of hydrate-based carbon capture. (C) 2021 Elsevier Ltd. All rights reserved.

Electrospinning technology is widely used for the generation of nano- or micro-sized fibers, which are capable of producing highly porous materials with high surface-to-volume ratios leading to various applications in algal bioprocesses. While the applications are mainly focused on cultivation and harvesting of algal cells on confined solid spaces, simultaneous processing of immobilized biomass during wastewater treatment has shown great potential in the removal of nitrate, heavy metals, and reactive dyes. Successful fabrication of electrospun materials directly from algal biomass and/or extracts is also possible and holds high promise for improving the sustainability of algal biotechnology. This chapter includes a general introduction of algae-associated electrospun composite materials, a detailed review of their applications in (i) cellular growth and biomass harvesting, (ii) integrated wastewater treatment processes, (iii) fabrication of electrospun fibers from whole algal biomass or algae extracts, and a final conclusion with suggestions regarding future directions of this research field.

Hydrate reformation may lead to production line blockage in the development of natural gas hydrate reservoirs. However, few studies have focused on the flow characteristics and plugging risks during the hydrate reformation process. Therefore, experiments on hydrate reformation were carried out in a high-pressure flow loop. The hydrate induction time and formation subcooling approached for the first hydrate formation and reformation. The pressure and temperature of the first formation and reformation onset fell in a subcooling band (2.0 +/- 0.5 degrees C). Furthermore, the flow stability of hydrate slurry for the reformation process was relatively poor compared with the first formation. Hydrate particles aggregated more violently during the reformation process when the initial flow rate was 1160 kg.h(-1). Moreover, the hydrate memory effect at the microlevel could be confirmed from two aspects, including an increasing number of methane microbubbles (MMBs) after hydrate dissociation and a shorter time required for the decrease in the number of MMBs during the reformation process. Then, the flow pattern evolutions were summarized for different experimental conditions, and the minimum flow rate of hydrate slurry with the stable flow ability could be predicted using the classical correlation. Finally, a prediction model was developed for predicting the pressure drop in hydrate slurry flow, which considered the hydraulic, particle-aggregation, and hydrate-liquid friction effects. The findings of this work provided an insight into the behavior of methane hydrate reformation in water-dominated bubbly flow, which is an advancing research topic in the field of development of natural gas hydrate reservoirs.

The hydrate-based carbon dioxide (CO2) capture (HBCC) process has been widely studied for CO2 separation and sequestration. This paper aims to conduct a model-based investigation of the kinetics of the HBCC process. A variation of the shrinking core model (SCM) was developed for the analysis of this heterogeneous system under varying boundary conditions. The results revealed that while CO2 diffusion through the hydrate layer is the dominant controlling mechanism, for a realistic scenario in which a time-dependent bulk gas concentration exists, the model results would better match the experimental data if the effects of the reaction rate were incorporated into the diffusion-based model. Sensitivity analysis showed that increasing the diffusivity through the hydrate layer significantly decreases the full conversion time of the water. Moreover, the effect of temperature change was investigated, and it was found that lower temperatures slow the hydrate growth rate. The model was demonstrated to be a computationally effective and time-efficient predictive tool that does not require high-speed computers for large-scale (reactor) applications.

Gas hydrates technology has been considered as an alternative method for carbon dioxide (CO2) separation. A wide range of studies have been reported in the past decade on the improvement of the separation efficiency by using chemical additives. While most of these studies have shown improved kinetics, thermodynamics and/or separation efficiency at the laboratory scale, there has been no quantitative analysis of the energy consumption for viable industrial applications. Comparison of the effectiveness of the chemical additives from separate studies or groups also is impossible. The present work is focused on the modelling of the hydrate-based CO2 separation process and provides a quantitative approach that is new in its analysis of the effectiveness of chemical additives in relation to the energy required and the kinetic parameters involved in the process.

BACKGROUND: Algal growth on solid surfaces confers the advantage of combining the algal harvesting and bioprocessing steps at a single stage, in addition to the easier handling of the immobilized cells that occupy reduced amount of space. The current work employed the application of macroporous poly(2-hydroxyethyl methacrylate) (PHEMA) hydrogel disks as a water-insoluble, non-toxic and recyclable immobilization matrix for different microalgal strains (Nannochloropsis sp., Dunaliella salina, and Botryococcus braunii) that offer valueadded products for various commercial applications. This article is protected by copyright. All rights reserved. This article has been accepted for publication and undergone full peer review but has not been through the copyediting, typesetting, pagination and proofreading process, which may lead to differences between this version and the Version of Record. Please cite this article as doi: 10.1002/jctb.5642 A cc ep te d A rti cl e RESULTS: The study demonstrated the effect of variations in the surface characteristics of the algal strains and hydrogel surfaces on the immobilization efficiencies. Gelatin was further used to modify PHEMA hydrogels for achieving higher bioaffinity and surface hydrophilicity. The results showed that highly salt-tolerant microalgal cells (Dunaliella salina, Nannochloropsis sp.) had significantly higher tendencies to attach on the gelatin-modified PHEMA hydrogel compare to the freshwater B. braunii colonies; embedded within an extracellular matrix mainly made of hydrophobic components; which displayed better attachment to the unmodified PHEMA hydrogels. CONCLUSION: The proposed PHEMA hydrogels are easily-manufactured and highly durable materials with the hydrogel disks still retaining their integrity after several years when in contact with a liquid. PHEMA disks also own the benefits of having adjustable porosities by changing the composition of the polymerization mixture, and modifiable surface properties by simply binding various synthetic or natural molecules on their surfaces, which can bring several new opportunities for harvesting of various microalgal cells with different surface morphologies and chemical compositions.

Novel 4-amino-2-methyl-8-(trifluoromethyl)quinoline based magnetic nanosensors, Fe3O4@SiO2-PEG-4AQ and Fe3O4@SiO2-4AQ, were successfully fabricated and characterised. Enhanced fluorescent intensity was demonstrated by both nanosensors. Upon complexation with zinc ions, a further enhancement of 13.5-fold was revealed by Fe3O4@SiO2-PEG-4AQ. A red shift of 42 nm was also observed. The presence of other metal cations including Ni2+, Co2+, Ca2+, Cd2+, Hg2+, Mg2+, Mn2+ and Ag+, showed no interference towards Zn2+. A sensitive detection limit of 0.0065 mu M and 0.0125 mu M was indicated by Fe3O4@SiO2-PEG-4AQ and Fe3O4@SiO2-4AQ respectively. The high sensitivity and selectivity remained constant within a wide range of pH values and were reversible upon treatment with EDTA. The PEG spacer between the magnetic core and the fluorophore offered further improvement of fluorescence intensity and detection sensitivity. To the best of our knowledge, this is the first study on 4-aminoquinoline based reusable nanochemosensor for zinc ion detection.

BACKGROUNDAlgal growth on solid surfaces confers the advantage of combining the algal harvesting and bioprocessing steps at a single stage, in addition to the easier handling of the immobilized cells that occupy a reduced amount of space. The current work employed the application of macroporous poly(2-hydroxyethyl methacrylate) (PHEMA) hydrogel disks as a water-insoluble, non-toxic and recyclable immobilization matrix for different microalgal strains (Nannochloropsis sp., Dunaliella salina, and Botryococcus braunii) that offer value-added products for various commercial applications. RESULTSThe study demonstrated the effect of variations in the surface characteristics of the algal strains and hydrogel surfaces on the immobilization efficiencies. Gelatin was further used to modify PHEMA hydrogels to achieve higher bioaffinity and surface hydrophilicity. The results showed that highly salt-tolerant microalgal cells (Dunaliella salina, Nannochloropsis sp.) had significantly higher tendencies to attach on the gelatin-modified PHEMA hydrogel compared with the freshwater B. braunii colonies; embedded within an extracellular matrix mainly made of hydrophobic components, which displayed better attachment to the unmodified PHEMA hydrogels. CONCLUSIONThe proposed PHEMA hydrogels are easily-manufactured and highly durable materials with the hydrogel disks still retaining their integrity after several years when in contact with a liquid. PHEMA disks also have the benefits of having adjustable porosities by changing the composition of the polymerization mixture, and modifiable surface properties by simply binding various synthetic or natural molecules on their surfaces, which can bring several new opportunities for harvesting various microalgal cells with different surface morphologies and chemical compositions. (c) 2018 Society of Chemical Industry

•Novel semiconductor photosensitisers (PS) for PDT were synthesised.•Photophysical properties, cytotoxicity and phototoxicity were evaluated.•Caco-2 cell viability was reduced to 6–11% by photo irradiated nano-PSs.•Folic acid conjugation enhanced the photo-killing effect.

Porous hydrogel particles of poly(2-hydroxyethyl methacrylate) (PHEMA) and poly(N-isopropylacrylamide) (PNIPAAm) with varying water absorbability and quantities were investigated upon their ability and stability to support the reversible methane hydrates storage in the presence of silica nanoparticles and water. Results from experimental and computational simulation indicated that the equilibrium water content and types of hydrogels, and the quantity of the hydrogel particles used in the mixture affect the hydrate formation kinetics. At the experimental condition of 4.5 MPa, all types of porous hydrogel particles were proved to be effective to store methane in the hydrates form. A storage capacity of 206 cm(3) methane gas (as at standard temperature and pressure) per gram water was achieved when the hydrate forming mixture contained four parts of PHEMA20, one part of silica nanoparticles and fifteen parts of water. Quantitative analysis using the shrinking-core model indicated that the presence of the hydrogel particles could increase the overall methane diffusivity and improve the hydrate formation kinetics, therefore the overall water conversion rate also enhanced. A strong reversibility was demonstrated by the added porous hydrogel particles. Changing water uptake by the hydrogel particles during the cool-thawing procedure was evident by the simulated water distribution data. The hydrogels with higher equilibrium water content, greater pore volumes and more stable porous structures and the lower operational pressure have shown better methane storage capacity and reversibility. (C) 2017 Elsevier Ltd. All rights reserved.