Colloidal Material Research Articles

Reductive pathways in molten inorganic salts enable colloidal synthesis of III-V semiconductor nanocrystals.

Colloidal quantum dots, with their size-tunable optoelectronic properties and scalable synthesis, enable applications in which inexpensive high-performance semiconductors are needed. Synthesis science breakthroughs have been key to the realization of quantum dot technologies, but important group III-group V semiconductors, including colloidal gallium arsenide (GaAs), still cannot be synthesized with existing approaches. The high-temperature molten salt colloidal synthesis introduced in this work enables the preparation of previously intractable colloidal materials. We directly nucleated and grew colloidal quantum dots in molten inorganic salts by harnessing molten salt redox chemistry and using surfactant additives for nanocrystal shape control. Synthesis temperatures above 425°C are critical for realizing photoluminescent GaAs quantum dots, which emphasizes the importance of high temperatures enabled by molten salt solvents. We generalize the methodology and demonstrate nearly a dozen III-V solid-solution nanocrystal compositions that have not been previously reported.

Implementation of Digital Computing by Colloidal Crystal Engineering with DNA.

Toehold-mediated strand displacement (TMSD) provides a versatile toolbox for developing DNA digital computing systems. Although different logic circuits with diverse functions have achieved good performance in terms of complexity and scalability, most previous DNA logic circuits perform information processing only at the molecular level, and nonspecific signal leakages are often difficult to avoid. Here, we demonstrate the feasibility of constructing leakless digital computing systems in three-dimensionally ordered colloidal supercrystals. These systems possess a unique signal leakage resistance by integrating different TMSD-based logic gates with the catalytic assembly of DNA-functionalized gold colloids. A complete set of basic Boolean logic gates and different cascaded logic circuits is constructed on the basis of the catalytic assembly strategy enabled by a facilely designed catassembler, where the output signals are recognized by determining whether specific colloidal supercrystals are formed or not. In addition, a half adder is built through a combination of XOR and AND logic gates with two distinct crystal types as readouts. Finally, a leakless two-digit DNA keypad lock for information security protection is demonstrated. The combination of TMSD-based logic circuits with the universal nanoparticle catalytic assembly offers the possibility to develop highly complicated and leakage-free digital computing systems and promotes macroscopic colloidal superlattice materials with programmable logic functions.

Brownian colloids in optothermal field: An experimental perspective

Colloidal matter undergoing Brownian motion serves as a model system to study various physical phenomena. Understanding the effect of external perturbation on the assembly and dynamics of “Brownian colloids” has emerged as a relevant research issue in soft matter and biological physics. Optical perturbation in the form of photonic forces and torques has added impetus to this exploration. In recent years, optothermal effects arising due to optical excitation of mesoscale matter have expanded the toolbox of light–colloidal matter interactions. In this perspective, we present an experimental viewpoint on some of the developments related to the assembly and dynamics of Brownian colloids driven by the optothermal field. Furthermore, we discuss some interesting prospects on driven colloidal matter that can have implications on soft matter physics and soft photonics.

Spontaneous Formation of π-Conjugated Polymeric Colloidal Molecules Through Stepwise Coacervation and Symmetric Compartmentalization.

Coacervation, the phase separation of liquid induced by polymeric solutes, sometimes results in the formation of oligomeric clusters of droplets. The morphology of the clusters is non-uniform because the clustering is a consequence of the random collisions of the drifting droplets. Herewereportdistinctively organized coacervation, yielding colloidal molecules with monodisperse size, morphological symmetry, and compositional heterogeneity.Weinvestigate the coacervation of a mixture of two types of synthetic polymers and find that one of the polymers coacervates first and serves as a core droplet, on which the other polymer coacervates subsequently to form satellite droplets. The satellite droplets arrange themselves symmetrically around the core and solidify without losing the morphology. The number of satellites and their symmetry are modulable depending on the chemical affinity and the diameter of the droplets. This finding highlights the capability of coacervation as a non-templated and non-covalent pathway to form aspherical colloidal materials with structural and functional complexity.

Development of Student Worksheets Based on a Scientific Approach to Colloidal System Material

The purpose of this study was to determine the feasibility of developing student worksheets based on a scientific approach, student responses and teacher responses to the developed student worksheets. The type of research used was research and development with a 4D model. The instruments used in this study were validation sheets and response questionnaires. Before the field trial was conducted, the student worksheets were validated by a team of experts to determine the shortcomings of the student worksheets, then revised and tested. The results showed that the average percentage obtained from the media expert validator was 80.66%, material experts 85.33%, and language experts 82.66%, with an average percentage of 82.88%, this indicates that the student worksheets can be used with feasible criteria. The percentage obtained from the results of student responses was 34% very interested, 55% interested, and 11% less interested. The percentage of teacher response results was 25% very interested, 65% interested, and 10% less interested, this shows that the student worksheets developed can be used in State Islamic High School 5, Aceh Besar. Research on the development of student worksheets based on a scientific approach to colloidal system material offers innovation in more interactive learning, encourages conceptual understanding through exploration and experimentation, and improves students' critical thinking skills.

High Temperature, Isothermal Growth Promotes Close Packing and Thermal Stability in DNA-Engineered Colloidal Crystals.

We report a strategy to accelerate the synthesis and increase the crystallinity of colloidal crystals (CCs) engineered with DNA. Specifically, by holding the DNA-modified Au particle building blocks above the Tm of the DNA bonding elements (i.e., free from the particles), but slightly below the Tm of the anticipated CC during the assembly process, crystallinity is increased, and enthalpically favored phases with high degrees of facet registration are observed. We studied the utility of this approach with systems for which the commonly adopted slow-cooling approach yielded primarily amorphous aggregates. In particular, we used it to synthesize high-volume fraction CCs from large (80 nm) anisotropic nanoparticles (cubes and rhombic dodecahedra) with short (<14 nm) DNA designed to restrict the degrees of freedom for the DNA bonds and maintain the anisotropy of the particle building block. Small-angle X-ray scattering and electron microscopy studies show that the crystalline phases synthesized via this method are more thermally stable than their corresponding aggregate phases, likely due to an increased number of DNA-DNA bonds between particles. Crystal size tunability (between 0.5 and 15 μm edge lengths) and epitaxial growth were demonstrated using this strategy by modulating the NaCl concentration in tandem with previously synthesized CC nuclei. Taken together, this isothermal strategy demonstrates how to deliberately crystallize a wide variety of anisotropic colloidal materials and expands the phase space accessible to nanoparticles modified with DNA.

Colloid chemical aspects of paper formation in the presence of nanofibrillated cellulose and cationic starch

A series of experimental tests were carried out to examine colloidal-scale consequences of optional-ly treating nanofibrillated cellulose (NFC) with cationic starches of different charge density and dosage (0.5% or 2.0% by weight), adding that material to a furnish prepared from 100% recycled copy paper, and then subjecting the mixture to very different levels of hydrodynamic shear. Tests included optical microscopy, sediment volume tests, sediment velocity tests, and “percent fines” assessment by means of a fiber quality analyzer (FQA). In addition, the zeta potential and charge demand of the studied materials were evaluated. Optical imaging revealed that cationic starch treatment of the NFC tended to agglomerate it into multiparticle clusters, which sometimes could be mostly redispersed by hydrodynamic shear. Subsequent addition of the starch-treated NFC to the default furnish resulted in much of the colloidal material becoming attached to fibers. Subsequent shearing of the mixtures was at least partly effective in separating the clusters of NFC from the fiber surface, resulting in essentially a two-component mixture. Multiparticle NFC clusters coexisted with the fiber suspension, sometimes attached and sometimes not, depending on the details of treatments. Sediment volume tests showed that systems containing cationic starch-treated NFC tended to have a higher density after settling in comparison to untreated NFC; these findings are consistent with the cationic starch acting as a stabilizer on the solid surfaces, allowing them to slide past each other during the settling process. Application of intense hydrodynamic shear tended to result in denser sediment. Results of tests with the sediment velocity measurement and the FQA percent fines assessment did not correlate well with changes in test conditions considered in this study.

Mass Conductivity in Drying Capillary-Porous Colloidal Material Susceptible to Shrinkage

Mass Conductivity in Drying Capillary-Porous Colloidal Material Susceptible to Shrinkage

Scientific and practical basis of cephalopods dehydration processes

Nowadays, it is relevant to solve the problems of adapting optimal resource- and energy-efficient modes to technologies for processing food raw materials. The work is focused on the analysis of the prerequisites to find similar features in the dehydration of food capillary-porous colloidal materials by means of various methods. The authors have studied the patterns of cephalopods dehydration using the example of octopus and squid under different heat treatment regimes. It has been proved that there is only one critical point characterizing the transition from moisture with a lower binding energy to moisture with a higher one, and an equation has been proposed for finding the critical humidity during dehydration of the objects been studied. A generalized mathematical model has been developed to determine the duration of the process at the current moisture content of the food material based on dimensionless similarity criteria characterizing the phenomena been investigated. The dependences of the moisture removal rate for different heat treatment methods of cephalopods are given according to their initial moisture content, the specific surface area of the material and the operating factors that determine the process. The obtained dependencies and patterns open up unique opportunities for labor-saving design in the food industry using rational operating modes of industrial enterprises, optimization of heat treatment processes in general and the creation of energy-efficient equipment new designs.

Preparation and flame retardant properties of new mining fireproof gel

Coal spontaneous combustion (CSC) brings great danger to mine safety. Although traditional colloidal fire-fighting materials can reside at high fire source points, their permeability and fluidity are poor, and such materials focus on their water absorption, but pay less attention to water retention and resistance, which makes their fire-fighting effect not good. This paper proposed a new type of mining fire prevention colloid material (CPS-α), which had good solid water gel formation, viscosity, fluidity, and blocking properties to compensate for traditional colloids' shortcomings. According to the single-factor experiment, polymeric polyacrylamide (PAM) as the base material, sodium carboxymethyl cellulose (CMC) as the coagulant, modified starch (SS) as the flame retardant and reduced ascorbic acid were determined. After gel treatment, compared with raw coal, the critical temperature point of spontaneous combustion of coal was increased by about 28 °C, the time to reach the critical temperature point was delayed by 190s, and the characteristic temperature points were significantly increased; the overlap area of coal and water increases by about 20 % after adding gel, and the change slope of the diffusion coefficient of water decreases, which indicated that CPS-α had good flame retardant effect.

Effectiveness of the Reading, Answering, Discussing, Explaining, and Creating (RADEC) Learning Model in Improving High School Students' Critical Thinking Skills on Colloid Material

Students need to be able to think critically in order to meet the challenges of the 21st century. Be that as it may, the decisive reasoning abilities of understudies are still somewhat low. The RADEC model is a learning model that can aid in the development of critical thinking abilities. The goal of this study is to find out how well the RADEC model helps students in high school think critically about colloidal materials. This study employs experimental, quantitative research techniques. The populace is all understudies in class XI MIPA at SMAN 5 Samarinda. The examples were understudies from class XI MIPA 2 and XI MIPA 4 at SMAN 5 Samarinda, adding up to 75 individuals. The exploration test was chosen utilizing a group irregular inspecting strategy. One-group pre-test post-test design was utilized in the research design. Information assortment involves tests as pre-tests and post-tests, educator and understudy movement perception sheets, and understudy reaction surveys. Statistical tests were conducted first, including the N-Gain test and the effect size test, for data analysis. According to the findings of the research, the RADEC model meets the effective criteria in terms of students' responses to learning based on the RADEC learning model and their increased critical thinking abilities. The findings of the research lead us to the conclusion that the RADEC model works to improve students' critical thinking abilities.

Characterization of Nanoparticles in Drinking Water Using Field-Flow Fractionation Coupled with Multi-Angle Light Scattering and Inductively Coupled Plasma Mass Spectrometry

The current absence of well-established and standardized methods for characterizing submicrometer- and nano-sized particles in water samples presents a significant analytical challenge. With the increasing utilization of nanomaterials, the potential for unintended exposure escalates. The widespread and persistent pollution of water by micro- and nanoplastics globally is a concern that demands attention, not only to reduce pollution but also to develop methods for analyzing these pollutants. Additionally, the analysis of naturally occurring nano entities such as bubbles and colloidal matter poses challenges due to the lack of systematic and consistent methodologies. This study presents Asymmetric Flow Field-Flow Fractionation (AF4) separation coupled with a UV-VIS spectrometer followed by Multi-Angle Light Scattering (MALS) for detection and size characterization of nanometric entities. It is coupled with an Inductively Coupled Plasma Mass Spectrometer (ICP-MS) for elemental analysis. Water samples from different sources, such as untreated mountain spring water, groundwater, and bottled drinking water, were analyzed. The system was calibrated using pure particle standards of different metallic compositions. Our study demonstrates the capability of AF4-UV-MALS-ICP-MS to detect metals such as Al, Ba, Cu, and Zn in particles of around 200 nm diameter and Mg associated with very small particles between 1.5 and 10 nm in different drinking water samples.

Operational management of water quality to prevent physical, chemical, and microbial contaminations in hydroponic cultivation

ABSTRACT The overarching aim of the present research is to manage the quality of surface water and irrigation water in hydroponic cultivation, which is one of the sustainable modern agricultural methods. It fully covered the control of physical, chemical, and biological contamination within the recommended standard range from river water to irrigation water. Initially, to deal with the corresponding contamination levels, the performance of the combination of coagulation and flocculation, rapid sand filter, ultrafiltration, and ultimately reverse osmosis methods were examined. By optimizing the pre-treatment section of coagulation and flocculation with jar tests, more than 90% removal of colloidal materials was achieved. Following the optimization of pre-treatment section, an 18.7% reduction in water consumption was observed. Finally, through the examination of the irrigation system and monitoring of both physical and biological contaminations, alongside the optimization of the greenhouse's recycled water disinfection system, preventive measures inhibiting the irrigation system clogging were implemented. The findings of the current research exhibited the removal of over 99% of these contaminations yielding a 99% reduction in the occurrence of irrigation system clogging.

Orbits, Spirals, and Trapped States: Dynamics of a Phoretic Janus Particle in a Radial Concentration Gradient.

A long-standing goal in colloidal active matter is to understand how gradients in fuel concentration influence the motion of phoretic Janus particles. Here, we present a theoretical description of the motion of a spherical phoretic Janus particle in the presence of a radial gradient of the chemical solute driving self-propulsion. Radial gradients are a geometry relevant to many scenarios in active matter systems and naturally arise due to the presence of a point source or sink of fuel. We derive an analytical solution for the Janus particle's velocity and quantify the influence of the radial concentration gradient on the particle's trajectory. Compared to a phoretic Janus particle in a linear gradient in fuel concentration, we uncover a much richer set of dynamic behaviors including circular orbits and trapped stationary states. We identify the ratio of the phoretic mobilities between the two domains of the Janus particle as a central quantity in tuning their dynamics. Our results provide a path for developing optimum protocols for tuning the dynamics of phoretic Janus particles and mixing fluid at the microscale. In addition, this work suggests a method for quantifying the surface properties of phoretic Janus particles, which have proven to be challenging to probe experimentally.

Distribution of Single-Particle Resonances Determines the Plasmonic Response of Disordered Nanoparticle Ensembles.

Understanding how colloidal soft materials interact with light is crucial to the rational design of optical metamaterials. Electromagnetic simulations are computationally expensive and have primarily been limited to model systems described by a small number of particles-dimers, small clusters, and small periodic unit cells of superlattices. In this work we study the optical properties of bulk, disordered materials comprising a large number of plasmonic colloidal nanoparticles using Brownian dynamics simulations and the mutual polarization method. We investigate the far-field and near-field optical properties of both colloidal fluids and gels, which require thousands of nanoparticles to describe statistically. We show that these disordered materials exhibit a distribution of particle-level plasmonic resonance frequencies that determines their ensemble optical response. Nanoparticles with similar resonant frequencies form anisotropic and oriented clusters embedded within the otherwise isotropic and disordered microstructures. These collectively resonating morphologies can be tuned with the frequency and polarization of incident light. Knowledge of particle resonant distributions may help to interpret and compare the optical responses of different colloidal structures, correlate and predict optical properties, and rationally design soft materials for applications harnessing light.

Analysis of Students’ Conceptual Understanding on Colloidal Materials Through the Flipped Classroom Learning Model Integrated Peer-Instruction

Analysis of Students’ Conceptual Understanding on Colloidal Materials Through the Flipped Classroom Learning Model Integrated Peer-Instruction

Amphiphilic Janus nanoparticles with controlled composition and wettability for pickering emulsion with controllable movement and release

Pickering emulsions represent an important class of functional materials with great potentials in field of sustainability and health, such as controlled drug release or catalysis. However, the limited tunability of the amphiphilicity and implementation of multiple components into Pickering emulsion are still challenges for reliable dynamic control. Here, a strategy to obtain a triphasic amphiphilic PS/Fe3O4@SiO2 Janus nanoparticles (JNPs) by cladding Fe3O4 NPs inside biphasic PS@SiO2 JNPs was proposed and validated. The sizes of the triphasic JNPs is in the range of 80–150 nm and water contact angle (θW) varies from 58.9° to 131.4°, indicating the wettability could be controlled at will. The formed JNPs are assembled at the oil-water interface to stabilize water-in-oil (W/O) and oil-in-water (O/W) emulsion droplets. The stabilized emulsion droplets exhibit excellent thermodynamic stability which is evidenced by the droplet viability of 50 %-80 % after 6 months or excellent salt and temperature-resistance. Moreover, the movement and demulsification are made possible with magnetic actuation of JNPs. Compared to without magnetism, the release of curcumin dissolved in water within W/O droplet was realized 70 % after 12 days, showing a promising application in controlled active material release. Taking advantage of controllable synthesis and the functionality, this proposed approach could be expanded for preparation of colloidal materials with complex chemical and incorporate additional functionality, suggesting opportunities for further applications in drug delivery, oil recovery fields, and other fields related Pickering emulsion.

The Deep Removal of Mercury in Contaminated Acid by Colloidal Agglomeration Materials M201

The high-temperature roasting/smelting process of copper and zinc concentrates will cause the mercury in the concentrate to evaporate into the flue gas, and most of the mercury in the flue gas will eventually enter the waste acid in its ionic form. A highly efficient mercury removal agent M201 with long carbon chains and loaded active functional groups can adsorb and disperse fine particles for mercury removal in the system. Through bridging, the linear structure is woven into a network to achieve large-scale capture and dispersion of fine particles and colloidal substances. The recommended operating conditions for developing mercury deep purification technology are as follows: M201 reagent concentration of 50 g/L, 6 mL/L added acid solution, room temperature, mixing time of 5 min, air flotation time of 10 min, ventilation rate of 0.1 L/min, H2SO4 concentration of 33.67 g/L, and the residual mercury content of 2 mg/L (the mercury content reaches 0.01 mg/L after two-stage mercury removal treatment). Meanwhile, the residual arsenic content is 21.9 mg/L. This study shows a better separation of arsenic and mercury and achieves one-step mercury removal.

Compositions, sources, and bioavailability of colloidal organic matter in Lake Taihu

Colloidal organic matter (COM) exists ubiquitously in natural waters, and plays a pivotal role in biogeochemical cycles. Lake Taihu is confronted with severe eutrophication and algal blooms. Field investigations were carried out in Lake Taihu and two inflow rivers for two years to identify the source of COM and explore the bioavailability of COM to algae. Compositions and sources of COM were analyzed through UV absorption coefficients and parallel factor analysis of three-dimensional excitation emission matrix spectra (3D EEMs-PARAFAC). Absorption coefficient a(350) of COM in rivers surpassed that in the lake, SUVA254 exhibited noteworthy seasonal variations, and SR indicated a stable autochthonous characteristic. Three components were identified by PARAFAC analysis: tryptophan-like (C1), humic-like (C2), and tyrosine-like (C3). Fluorescence indexes showed that C1 and C3 were mainly autochthonously produced and C2 was derived from allochthonous inputs. The bioassays were conducted to assess the bioavailability of COM to the dominant species, Microcystis aeruginosa. The results showed that colloids supplied rich carbon sources and trace metals, supporting the growth of Microcystis aeruginosa. The specific growth rate, Chl a content, and biological increment of Microcystis aeruginosa in 50 % colloid-added treatment exceeded those in 20 % and 75 % treatments. Simultaneously, the effective quantum yield (Fv/Fm) and the apparent photosynthetic electron transport rate (ETRmax) demonstrated that the photosynthetic activity of Microcystis aeruginosa was higher in 20 % treatment. These findings help in understanding the intricate mechanisms of COM in lake ecosystems, and provide the robust scientific foundation for water management and protection in Lake Taihu.

Size and polarity fractions of mobile organic matter from manure affect the sorption of sulfadiazine, caffeine and atenolol in soil

Waste-derived organics introduced to soils along with pharmaceutical active compounds (PhAC) are a crude mixture of compounds occurring in various size and polarity fractions. They affect the sorption of PhACs to soil; however, the relevant knowledge is still insufficient. The effects of different size and polarity fractions of manure-derived mobile organic matter (<63 µm) on the sorption of sulfadiazine, caffeine and atenolol to five topsoils were investigated. Mobilization of the PhACs was strongest in the presence of dissolved organic matter (mDOM, <0.45 µm), with a reduction of Kd of sulfadiazine, caffeine and atenolol by mean factors of 0.66, 0.57 and 0.41, respectively. The mobilizing effects of colloidal organic matter (0.45–10 µm) were slightly smaller. Fine particulate organic matter (10–63 µm) reduced the sorption of the PhACs in slightly acidic soils (pH 6.0), but increased it in strongly acidic soil (pH 4.3). Furthermore, hydrophobic (HO-mDOM) and hydrophilic (HI-mDOM) fractions of mDOM reduced the sorption capacity but increased the sorption nonlinearity of PhACs in soils. Effects of HO-mDOM and HI-mDOM were PhAC specific. It is suggested to consider the varying impacts of mobile fractions in animal manure and/or treated wastewater in evaluating the fate and environmental relevance of associated PhACs.