Tunable Size Research Articles

Large-scale and facile fabrication of phenyl-containing silicone foam materials with lightweight, wide-temperature flexibility and tunable pore structure for exceptional thermal insulation

Silicone foam materials with unique inorganic/organic molecular networks and porous structures are widely used in many emerging fields from aerospace to new energy fields. However, current silicone foam materials still show some limitations, such as the relatively high-density values of >200 mg cm−3, complex fabricating process and difficulty in tailoring pore structure. Herein, we report a large-scale and facile fabricating strategy to prepare phenyl-containing silicone foam materials (PhSiRF) with ultra-lightweight feature, tunable pore structure, and excellent wide-temperature mechanical flexibility. Interestingly, the presence of phenyl groups onto the Si–O–Si backbone tailors the chemical foaming rate probably due to the steric hindrance effect, thus producing tunable pore size distributions in the range of 180–500 μm. Typically, the PhSiRF with 50 % phenyl groups not only shows a very low density of ∼100 mg cm−3, superior to previous silicone foams and composites, but also exhibits wide-temperature flexibility (stable compressive strain of 80 % from −90 to 210 °C) and excellent thermal insulation performance, which outperforms those of conventional polymer foams including polyurethane, polyethylene and melamine foams. Based on the structure observation and theory analysis, the influence of different pore morphological structures on the thermal insulation performance is discussed and demonstrated. Clearly, this work provides a new yet simple method for developing high-performance silicone rubber foam materials for promising thermal insulation applications.

Probing the interaction between biomolecules under sub-zero temperature conditions by electrophoresis in ice grain boundaries

BackgroundPsychrophiles can survive under cryogenic conditions because of various biomolecules. These molecules interact with cells, ice crystals, and lipid bilayers to enhance their functionality. Previous studies typically measured these interactions by thawing frozen samples and conducting biological assays at room temperature; however, studying these interactions under cryogenic conditions is crucial. This is because these biomolecules can function at lower temperatures. Therefore, a platform for measuring chemical interactions under sub-zero temperature conditions must be established. ResultsThe chemical interactions between biomolecules under sub-zero temperature conditions were evaluated within ice grain boundaries with a channel-like structure, which circumvents the need for thawing. An aqueous solution of sucrose was frozen within a microfluidic channel, facilitating the formation of freeze-concentrated solutions (FCSs) that functioned as size-tunable electrophoretic fields. Avidin proteins or single-stranded DNA (ssDNA) were introduced into the FCS in advance. Probe micro/nanospheres whose surfaces were modified with molecules complementary to the target analytes were introduced into the FCS. If the targets have functionalities under sub-zero temperature conditions, they interact with complementary molecules. The chemical interactions between the target molecules and nanospheres led to the aggregation of the particles. The size tunability of the diameter of the FCS channels enabled the recognition of aggregation levels, which is indicative of interaction reactivity. The avidin–biotin interaction and ssDNA hybridization served as models for chemical interactions, demonstrating interactivity under sub-zero temperature conditions. The results presented herein suggest the potential for in situ measurement of biochemical assays in the frozen state, elucidating the functionality of bio-related macromolecules at or slightly below 0 °C. SignificanceThis is the first methodology to evaluate chemical interactions under sub-zero temperature conditions without employing the freeze-and-thaw process. This method has the advantage of revealing the chemical interactions only at low temperatures. Therefore, it can be used to screen and evaluate the functionality of cryo-related biomolecules, including cold-shock and antifreeze proteins.

Synthesis of NaYbF4:Er nanocrystals with controllable size, morphology, and multicolor upconversion luminescence for Anticounterfeiting applications

The dopant concentration of lanthanide ions plays one of the critical roles to manipulate size/morphology, photon population pathway, or luminescence color/intensity in upconversion nanoparticles (UCNCs), which have a significant effect on their application developments. Herein, a strategy is demonstrated for simultaneous size, morphology and multicolor luminescence tuning in the single doped lanthanide activator Er3+ ion system through simply tuning the concentration of Er3+ ions. The doping of different Er3+ ion amounts in NaYbF4:Er nanocrystals can control nanoparticle size (from several hundreds to tens of nanometers) and morphology. Moreover, multicolor upconversion luminescence involving green, yellow, orange and red can be obtained in the NaYbF4:Er UCNCs by changing the excitation power density of 980 nm laser. Mechanistic studies reveal the size and morphology evolution process as well as saturation/cross relaxation effects induced tunable multicolor emissions. These nanocrystals have demonstrated promising potential applications in anticounterfeiting. Our results not only provide a simple and feasible route for simultaneous size/morphology control and multicolor upconversion luminescence tuning, but also can further expand the utility of UCNCs in the frontier applications ranging from optical encoding to information security.

Insights for the strength and ductility of precipitation hardening Al–Li–Sc alloys

Al–Li alloys with high elastic modulus, low density and high specific strength have been widely used in aerospace industry. However, although Al3Li precipitates enhance the strength significantly, the appearance of shearable Al3Li precipitates usually decreases the ductility, leading to the strength-ductility trade-off. In this study, the strategy of microalloying is applied to fabricate an Al–2.46 Li–0.2 Sc (wt.%) alloy with tunable precipitate sizes by heat treatment. This alloy exhibits a good combination of strength and ductility when the precipitate radius is smaller than 6.7 nm or larger than 16.4 nm. The strengthening mechanisms in Al–Li–Sc alloy with different precipitate sizes are quantitatively discussed. With the increase of precipitate size, the dominant precipitation strengthening mechanism changes. The influence of precipitate on ductility is mainly achieved by influencing the dynamic recovery rate of dislocation which can be illustrated by a dislocation-based model. When the precipitate size is relatively small or large, the Al–Li–Sc alloy exhibits a higher ductility owing to a lower dynamic recovery rate. This study provides insight for understanding the strength and ductility in Al–Li–Sc alloy as well as potential theoretical guideline for designing novel high-performance Al–Li based alloys.

Amino-Functionalizing Ce-Based MOF UiO-66 for Enhanced CO2 Adsorption and Selectivity.

Metal-organic frameworks (MOF) hold great promise for CO2 adsorption due to their high surface areas, tunable pore sizes, and the ability to modify their chemical properties to enhance CO2 affinity. MOFs tagged with functional groups either at linker or metal sites have shown improved CO2 uptake capacity and selectivity. This study focuses on investigating the potential of selective CO2 adsorption using amino functionalization of linker forming Ce-UiO-66. The physicochemical properties and characteristics of MOFs to determine the degree of amino functionalization and structural stability were examined using powder X-ray diffraction (PXRD), Fourier transformer infra-red (FTIR), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and N2 porosimetry and specific surface area (BET). This work unveils a novel array of results on CO2, N2 and water vapour adsorption on Ce-UiO-66-NH2. The amino-functionalized Ce-UiO-66-NH2 shows 63 % higher CO2 uptake and 84 % higher CO2/N2 selectivity at 273 K and 1 bar over Ce-UiO-66. Ce-UiO-66-NH2 also shows excellent structural stability after gas and vapour sorption making Ce-UiO-66-NH2 potential adsorbent for CO2 capture.

Synthesis study of size-controlled rhenium nanoparticle systems using reverse micelle-based methodologies

In this study, rhenium nanoparticles were successfully synthesized with precise size control using a water-in-oil microemulsion method under an ambient atmosphere. Spectroscopic characterization using UV-Vis and ESI-MS techniques was used to study the stability of the rhenium(IV) precursor and verify its reduction into rhenium-based nanoparticles. The morphology and size of the rhenium nanoparticles were examined using HR-TEM. The results indicate formation of amorphous rhenium nanoparticles with an average size of 2.2 nm at a water-to-surfactant concentration ratio (W factor) of 10. These rhenium nanoparticles also have good size-stability compared to rhenium colloids generated in water alone. After one week, the particle diameter increased by only 0.6 nm with no evidence of aggregation. An investigation into the effect of various factors on the size and size distribution of the rhenium nanoparticles indicate that the W factor is the most influential parameter (among the considered factors) for size tuning, given that increases in W led to bigger and more polydisperse particles. Additionally, the microemulsion surfactant (AOT) protects the rhenium nanoparticles from their natural tendency to oxidize to perrhenate ion under an air atmosphere. However, a significant consideration in the use of AOT is the previously unreported presence of a chemical impurity which is able to reduce the rhenium(IV) precursor salt and generate rhenium nanoparticles within these microemulsion systems. Our investigation found that this impurity is the sulfite ion which is most likely introduced during manufacturing.

The influence of electrode types to the visually induced gamma oscillations in mouse primary visual cortex.

The local field potential (LFP) is an extracellular electrical signal associated with neural ensemble input and dendritic signaling. Previous studies have linked gamma band oscillations of the LFP in cortical circuits to sensory stimuli encoding, attention, memory, and perception. Inconsistent results regarding gamma tuning for visual features were reported, but it remains unclear whether these discrepancies are due to variations in electrode properties. Specifically, the surface area and impedance of the electrode are important characteristics in LFP recording. To comprehensively address these issues, we conducted an electrophysiological study in the V1 region of lightly anesthetized mice using two types of electrodes: one with higher impedance (1MΩ) and a sharp tip (10μm), while the other had lower impedance (100 KΩ) but a thicker tip (200μm). Our findings demonstrate that gamma oscillations acquired by sharp-tip electrodes were significantly stronger than those obtained from thick-tip electrodes. Regarding size tuning, most gamma power exhibited surround suppression at larger gratings when recorded from sharp-tip electrodes. However, the majority showed enhanced gamma power at larger gratings when recorded from thick-tip electrodes. Therefore, our study suggests that microelectrode parameters play a significant role in accurately recording gamma oscillations and responsive tuning to sensory stimuli.

High-yield fabrication of monodisperse multilayer nanofibrous microparticles for advanced oral drug delivery applications

Recent advances in the use of nano- and microparticles in drug delivery, cell therapy, and tissue engineering have led to increasing attention towards nanostructured microparticulate formulations for maximum benefit from both nano- and micron sized features. Scalable manufacturing of monodisperse nanostructured microparticles with tunable size, shape, content, and release rate remains a big challenge. Current technology, mainly comprises complex multi-step chemical procedures with limited control over these aspects. Here, we demonstrate a novel technique for high-yield fabrication of monodisperse monolayer and multilayer nanofibrous microparticles (MoNami and MuNaMi respectively). The fabrication procedure includes sequential electrospinning followed by micro-cutting at room temperature and transfer of particles for collection. The big advantage of the introduced technique is the potential to apply several polymer-drug combinations forming multilayer microparticles enjoying extracellular matrix (ECM)-mimicking architecture with tunable release profile. We demonstrate the fabrication and study the factors affecting the final three-dimensional structure. A model drug is encapsulated into a three-layer sheet (PLGA-pullulan-PLGA), and we demonstrate how the release profile changes from burst to sustain by simply cutting particles out of the electrospun sheet. We believe our fabrication method offers a unique and facile platform for realizing advanced microparticles for oral drug delivery applications.

Unlocking the Potential of Gold as Nanomedicine in Cancer Immunotherapy

Nanotechnology advancements have resulted in many sensors and devices for biomedical applications. Among the various nanomaterials, gold nanoparticles (AuNPs), due to their size, shape, biocompatibility, and unique plasmonic property, are an excellent candidate for many biomedical applications. AuNPs, known for their easy surface modifications, robust nature, and photothermal activities, find application in drug delivery and cancer treatment studies. In this review, we are highlighting the recent trends in using AuNPs as nanomedicine for cancer immunotherapy. Cancer immunotherapy not only eliminates the primary tumors but also allows for the treatment of metastasis along with the recurrence of the tumor. AuNPs possess tissue-specific delivery functions that depend on the tunability in size and surface functionalization of AuNPs. AuNPs can be used to activate the tumor’s immune defense ability, or they can be used to enhance the anti-tumor immune response. Understanding the interaction of the tumor environment and nanobiomedicine is very important. In the present review, we give an idea of the mode of action of AuNPs and various combinations of therapies for cancer immunotherapy.

Synthesize and Characterization of Pt-supported Co-ZIF for Catalytic Hydrocracking and Hydroisomerization of n-Hexadecane

Zeolitic Imidazole Frameworks (ZIFs) are prospective porous materials as catalyst support due to their relatively large surface area, and tunability in size, structure, and porosity. Recent studies have also shown that ZIF is the best candidate for various catalytic redox reactions such as the oxidation of benzyl aromatic hydrocarbons. In this study, the synthesized Pt catalyst supported on Co-ZIF was varied by the organic ligands: imidazole, benzimidazole, and 1-(3-aminopropyl) imidazole, then followed by impregnation of Pt precursor. The catalysts were characterized its physical and chemicals properties such as Fourier Transform Infrared (FTIR), X-ray Diffraction (XRD), Scanning Electron Microscope (SEM), and Brunauer Emmet Teller (BET), Temperature-Programmed Desorption (NH3-TPD and CO2-TPD). The prepared catalysts were evaluated for catalytic hydrocracking and hydroisomerization of n-hexadecane in a 100 ml-batch reactor. GC-MS analysis presented that the Pt/ZIF catalyst with imidazole ligands has better performance than others. Hence, the optimization of n-Hexadecane conversion was carried out by the Pt/ZIF-imidazole catalyst varying the amount of metal loading, time and temperature reaction. The results showed that the reaction temperature of 350 ºC using 20 bar H2 for 4 h and the addition of 15 wt% Pt successfully achieved 90.77% conversion and produced the highest yield of isomers and alkanes, 4.04% and 35.75%, respectively. Copyright © 2024 by Authors, Published by BCREC Publishing Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Transfer learning-assisted computational screening of metal-organic frameworks and covalent-organic frameworks for the separation of Xe/Kr noble gas

The adsorption separation of xenon/krypton (Xe/Kr) by porous materials has gained significant attention in industrial development. Metal-organic frameworks (MOFs) and covalent-organic frameworks (COFs) featuring permanent porosity, ultra-high surface area, and tunable pore size enable efficient separation of Xe/Kr, which promising structures can be identified by high-throughput computational screening and machine learning. However, the asymmetric development of the structure database between MOFs and other porous materials (including COFs) led to a data imbalance that challenged screening and machine learning for other porous materials, especially for computation-ready experimental (CoRE) databases. Transfer learning (TL) can address this issue by extracting the information from MOFs to improve generalization for other materials. In this work, geometric, energy, and chemical-based descriptors were obtained from MOFs and COFs to train TL models. It was demonstrated that TL with only 300 data sets of hypothetical COFs being used can produce satisfactory accuracy (R2 > 0.85) by predicting CoRE COFs based on CoRE MOFs. Furthermore, we conducted a feature importance analysis that suggested the energy descriptor plays a dominant role in predicting the Xe/Kr separation performance of the ensemble algorithm, whereas the chemical descriptor is an important descriptor for the deep neural network. This study provides an alternative transfer learning route to predict the Xe/Kr separation performance of nanoporous materials database with limited structures.

Covalent triazine framework-based porous mixed matrix membranes for highly efficient dye/salt separation

Mixed matrix membranes (MMMs) incorporating porous covalent organic frameworks (COFs) as fillers have garnered significant attention in membrane separation for water purification. Covalent triazine frameworks (CTFs) possess high thermochemical stability, an inherent triazine conjugate structure, and tunable pore size. Despite these attributes, CTFs have been underutilized in MMMs. In this study, CTF-based porous MMMs were fabricated by blending 4,4′-biphenyldicarbonitrile (BPCN) monomer with polyacrylonitrile (PAN) and employing titanium dioxide nanoparticles (TiO2 NPs) as a pore-forming agent. The nature of PAN also makes the mixed matrix membranes have better hydrophilicity and mechanical properties. The optimized CTF-MMM exhibited an impressive water permeance of ∼ 204 L m−2 h−1 bar−1, accompanied by a remarkable dye rejection of ∼ 99 % and a low salt rejection. Moreover, the CTF-MMM demonstrated sustained water permeance and separation performance even after 48 h. This work introduces a synthesis strategy for fabricating high-performance CTF-based porous mixed matrix membranes, showcasing significant potential for applications in dye/salt separation.

Role of Silica, Carbon, and ZnO Nanomaterials in the Fabrication of Electrochemical Sensors for the Detection of Water Contaminants and Food Dye

AbstractSilica‐based nanomaterials have attracted huge attention for maximizing their safety and efficacy due to their nontoxicity, chemical and thermal stability, size tunability, and versatile functionality. Nanosilica with ZnO or carbon in a composite has excellent usage as an electrochemical sensor. Recent technological progression in nanotechnology and nanoscience has seen a number of applications of zinc oxide (ZnO) nanomaterials ranging from electronics, and sensing to environmental, and biomedical applications because of its various applications, multifunction, high specific surface area, stability, biocompatibility, nontoxicity, electrochemical activities, and so on. Carbon also has various advantageous properties like renewability, low ohmic resistance, and very stable response due to which carbon paste electrodes have attracted attention in the fabrication of electrochemical sensors. Electrochemical sensors are inexpensive, portable, and have excellent ability in detecting water contaminants, pesticides, disinfectants, pathogens, and different molecules. Artificial dyes are usually mixed with vegetable sauces, drinks, and other food items, which can cause cancer in human body. Voltametric methods with electrochemical sensors can be used to detect them in food samples. In this review, the present applications of ZnO and carbon nanomaterial‐based chemical sensors are meticulously studied to detect water contaminants and food dyes where nanosilica plays an important role as a sensor modifier.

A Versatile Synthesis Platform Based on Polymer Cubosomes for a Library of Highly Ordered Nanoporous Metal Oxides Particles.

Polymer cubosomes (PCs) have well-defined inverse bicontinuous cubic mesophases formed by amphiphilic block copolymer bilayers. The open hydrophilic channels, large periods, and robust physical properties of PCs are advantageous to many host-guest interactions and yet not fully exploited, especially in the fields of functional nanomaterials. Here, the self-assembly of poly(ethylene oxide)-block-polystyrene block copolymers is systematically investigated and a series of robust PCs is developed via a cosolvent method. Ordered nanoporous metal oxide particles are obtained by selectively filling the hydrophilic channels of PCs via an impregnation strategy, followed by a two-step thermal treatment. Based on this versatile PC platform, the general synthesis of a library of ordered porous particles with different pore structures , tunable large pore size (18-78nm), high specific surface areas (up to 123.3m2g-1 for WO3) and diverse framework compositions, such as transition and non-transition metal oxides, rare earth chloride oxides, perovskite, pyrochlore, and high-entropy metal oxides is demonstrated. As typical materials obtained via this method, ordered porous WO3 particles have the advantages of open continuous structure and semiconducting properties, thus showing superior gas sensing performances toward hydrogen sulfide.

Ultrasmall CsPbBr3 Blue Emissive Perovskite Quantum Dots Using K-Alloyed Cs4PbBr6 Nanocrystals as Precursors.

We report a colloidal synthesis of blue emissive, stable cube-shaped CsPbBr3 quantum dots (QDs) in the strong quantum confinement regime via dissolution-recrystallization starting from pre-syntesized (K x Cs1-x )4PbBr6 nanocrystals which are then reacted with PbBr2. This is markedly different from the known case of Cs4PbBr6 nanocrystals that react within seconds with PbBr2 and get transformed into much larger, green emitting CsPbBr3 nanocrystals. Here, instead, the conversion of (K x Cs1-x )4PbBr6 nanocrystals to CsPbBr3 QDs occurs in a time span of hours, and tuning of the QD size is achieved by adjusting the concentration of the precursors. The QDs exhibit excitonic features in optical absorption that are tunable in the 420-452 nm range, accompanied by blue photoluminescence with quantum yield around 60%. Detailed spectroscopic investigations in both the single and multiexciton regime reveal the exciton fine structure and the effect of Auger recombination of these CsPbBr3 QDs, confirming theoretical predictions for this system.

Efficient decolorization performance of graphene quantum dots modulated nanofiltration membranes with tunable pore size for precise molecular sieving

The discharge of wastewater containing dyes not only causes serious environmental pollution but also poses a severe threat to human health. The selective separation of dyes and reuse of inorganic salts are vital in the textile industry. In this work, nitrogen-doped graphene quantum dots (N-GQDs) was successfully synthesized via the “one-step solvothermal method”, and the N-GQDs composite membranes were innovatively fabricated by constructing a thin selective layer top the modified multi-walled carbon nanotubes (MWCNTs) matrix membrane via interfacial polymerization process. The pore size of the N-GQDs membranes could be flexibly modulated by regulating the contents of the N-GQDs. The suitable N-GQDs membrane (M4, 0.35 wt% of N-GQDs) possessed over 96 % rejection rate for diverse charged dyes, which was higher than that of the piperazine polyamide (PA3) membrane. Notably, the rejection of the smaller molecular weight of Methylene Blue by the M4 membrane reached ∼98.93 %, which was higher than that reported in most literature, mainly owing to the relatively smaller average pore size and stronger electronegativity of the membrane. Especially compared with our previous work, the prepared M3 and M4 membranes exhibited an enhancement of ∼37.79 % and 39.48 % in rejection of Methylene Blue, ∼ 78 % and 19 % in pure water permeability, respectively. On account of the size sieving and charge effect, the N-GQDs membrane (M4) could maintain high rejection for dyes and exhibited efficient separation for dye/salt with a separation factor of 115 for the Congo Red/sodium chloride mixture after continuous cross-flow filtration for 24 h in the simulated wastewater condition. Furthermore, the N-GQDs membrane also exhibited favorable acid-base resistance and satisfactory anti-fouling performance. Importantly, the N-GQDs membranes presented excellent decolorization efficiency for the practical textile wastewater. These results revealed that the as-prepared N-GQDs membrane possessed great potential for actual textile wastewater advanced treatment and purification. This study also offers a new candidate to rationally manipulate the separation properties of nanofiltration membranes adopting new aqueous monomers.

Convolutional neural networks develop major organizational principles of early visual cortex when enhanced with retinal sampling.

Primate visual cortex exhibits key organizational principles: cortical magnification, eccentricity-dependent receptive field size and spatial frequency tuning as well as radial bias. We provide compelling evidence that these principles arise from the interplay of the non-uniform distribution of retinal ganglion cells, and a quasi-uniform convergence rate from the retina to the cortex. We show that convolutional neural networks outfitted with a retinal sampling layer, which resamples images according to retinal ganglion cell density, develop these organizational principles. Surprisingly, our results indicate that radial bias is spatial-frequency dependent and only manifests for high spatial frequencies. For low spatial frequencies, the bias shifts towards orthogonal orientations. These findings introduce a novel hypothesis about the origin of radial bias. Quasi-uniform convergence limits the range of spatial frequencies (in retinal space) that can be resolved, while retinal sampling determines the spatial frequency content throughout the retina.

Gel-casting of mesoporous silica electrolyte membranes loaded with phosphoric acid for protonic electrolyte cells

Proton conducting membranes that operate at temperatures above 100 °C are highly sought after for use in energy devices such as fuel cells owing to the high catalytic activity of electrodes induced by elevated temperature and no requirement for water management. In the present study, novel mesoporous silica membranes were prepared by a gel-casting process using commercial colloidal silica and subsequent sintering. These membranes served as the scaffold for phosphoric acid-based electrolytes. Well-interconnected mesopores with uniform pore sizes was effective for hosting phosphoric acid (PA), and the tunable pore sizes (5.9–32.0 nm) were achieved by tuning the sintering temperature from 500 to 725 °C. High porosity (about 50%) and high hydrophilicity of silica membranes are beneficial to reach high phosphoric acid loading by an impregnation process. The PA-loaded membrane sintered at 700 °C achieved a high protonic conductivity of 0.11 S cm−1 and a peak power density of 287.3 mW cm−2 in hydrogen fuel cells at 160 °C. The conductivity is 1 order of magnitude higher than that of the pressed meso-silica membranes and comparable to that of PA-mesoporous silica spheres. This study has demonstrated a new method to construct high-temperature protonic electrolyte membranes.

Green preparation of versatile silver-based nanocomposites using whole biomass-based Tannin-Furfural as raw materials

Phenolic resin (PR) nanomaterials, which serve as excellent carriers for precious metals, are typically synthesized via the cross-linked reaction of phenol and formaldehyde, and both are toxic. Therefore, replacing them with whole biomass-based materials is an attractive alternative; however, it has proven to be a significant challenge. In this study, we successfully prepared versatile Ag-based resin nanocomposites (referred to as TFR@Ag) by utilizing whole biomass-based tannin and furfural as raw feedstock. The resulting TFR nanospheres exhibited high stability and uniformity, with tunable sizes ranging from 280 to 1430 nm by adjusting the amount of ammonia used in the synthesis process. Importantly, compared to traditional PR nanospheres, the novel and environmentally friendly TFR nanospheres possess abundant phenolic-OH groups that significantly enhance their adsorption, reduction and chelation capacity for Ag+. The highest loading amount of silver nanoparticles (Ag NPs) achieved was up to 60.3 wt% with a size of only 10.6 nm. The as-obtained TFR@Ag nanocomposites demonstrated excellent catalytic activity in treating typical hazardous dye-containing wastewater. As catalyst, the 0.4 mg TFR@Ag were capable of achieving full reduction of 2 mL 40 mg·mL−1 methylene blue (MB) and methyl orange (MO) in just one minute, exhibiting reaction rate constants of 1.71 min−1 and 2.40 min−1, respectively. Moreover, as antibacterial agents, the TFR@Ag nanocomposite effectively inhibited the growth of Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) with a bacterial inhibition rate close to 100 %. This work presents a new strategy for green synthesis of multi-functional Ag-based nanocomposites that hold great potential in various fields such as catalysis, nanomaterials science and biomedicine.

Microfluidic preparation of surfactant-free ultrafine DAAF with tunable particle size for insensitive initiator explosives

High purity and ultrafine DAAF (u-DAAF) is an emerging insensitive charge in initiators. Although there are many ways to obtain u-DAAF, developing a preparation method with stable operation, accurate control, good quality consistency, equipment miniaturization, and minimum manpower is an inevitable requirement to adapt to the current social technology development trend. Here reported is the microfluidic preparation of u-DAAF with tunable particle size by a passive swirling microreactor. Under the guidance of recrystallization growth kinetics and mixing behavior of fluids in the swirling microreactor, the key parameters (liquid flow rate, explosive concentration and crystallization temperature) were screened and optimized through screening experiments. Under the condition that no surfactant is added and only experimental parameters are controlled, the particle size of recrystallized DAAF can be adjusted from 98 nm to 785 nm, and the corresponding specific surface area is 8.45 m2·g−1 to 1.33 m2·g−1. In addition, the preparation method has good batch stability, high yield (90.8%–92.6%) and high purity (99.0%–99.4%), indicating a high practical application potential. Electric explosion derived flyer initiation tests demonstrate that the u-DAAF shows an initiation sensitivity much lower than that of the raw DAAF, and comparable to that of the refined DAAF by conventional spraying crystallization method. This study provides an efficient method to fabricate u-DAAF with narrow particle size distribution and high reproducibility as well as a theoretical reference for fabrication of other ultrafine explosives.