Brittleness has hindered commercialization of cellulose nanofibril (CNF) films. The use of synthetic polymers and plasticizers is a known detour that impairs biodegradability and carbon footprint of ...the product. Herein, we utilize a variety of softwood Kraft lignin morphologies to obtain strong and ductile CNF nanocomposite films. An optimum 10 wt % content of colloidal lignin particles (CLPs) produced films with nearly double the toughness compared to a CNF film without lignin. CLPs rendered the films waterproof, provided antioxidant activity and UV-shielding with better visible light transmittance than obtained with irregular lignin aggregates. We conclude based on electron microscopy, dynamic water sorption analysis, and tp-DSC that homogeneously distributed CLPs act as ball bearing lubricating and stress transferring agents in the CNF matrix. Overall, our results open new avenues for the utilization of lignin nanoparticles in biopolymer composites equipped with versatile functionalities for applications in food packaging, water purification, and biomedicine.
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IJS, KILJ, NUK, PNG, UL, UM
The separation of micro and nanoscale colloids is a necessary step in most biological microassay techniques, and is a common practice in microchemical processing. Chemical waves are frequently ...encountered in biochemical systems driven far from equilibrium. Here, we put forward a strategy for separating small suspending colloids by means of their surfing on substrate chemical wavefronts. The colloids with catalytic activities sensitive to the substrates are activated to show self-propulsion and consequently exhibit a chemotactic response to the traveling wavefronts, which results in their spontaneous separation from the multicomponent complex mixture via self-diffusiophoresis. The dynamics of the process is analyzed through a particle-based simulation. In addition, it is found that separation can be carried out according to particle size. The mechanisms underpinning the chemical and physical separation processes are discussed, and the dependencies on the reaction rate constant and particle size are presented. The results may prove relevant for further experimental and theoretical studies of separation in complex active environments.
Nanoscale zero-valent iron (NZVI) particles are usually modified with surface coating to mitigate the particle stability in water during the environmental application. However, the surface coating ...may not only influence the particle stabilization but also the particle cytotoxicity. In this study, we investigated the dual effects of carboxymethyl cellulose (CMC) on the colloidal stability and cytotoxicity of NZVI towards gram-negative Escherichia coli (E. coli) and discussed the interrelation between particle stability and cytotoxicity. The effect of CMC concentration, ionic strength (Ca2+) and aging treatment on the particle cytotoxicity were also examined. Specifically, the aqueous stability of NZVI suspensions with CMC ratio dose-dependently strengthened within 1 h. The inactivation of E. coli by bare NZVI was significant and concentration- and time-dependent. On the contrary, an increasing reduction in cytotoxicity of NZVI with CMC ratio increasing was observed, even though the particles became more dispersed. TEM analysis demonstrates the membrane disruption and the cellular internalization of nanoparticles after exposure of E. coli to NZVI. However, in the case of CMC-modified NZVI (CNZVI), the bacterial cell wall displays an outer shell of a layer of nanoparticles attached around the outer membrane, but the cell membrane was kept intact. The presence of Ca2+ can either increase or decrease the cytotoxicity of NZVI and CNZVI, depending on the concentration. The aged NZVI and CNZVI particles did not seem to present obvious bactericidal effect due to the transformation of Fe0 to the less toxic or non-toxic iron oxides, as indicated by the XRD analysis.
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•The dual effects of CMC on the stability and cytotoxicity of NZVI were investigated.•The CMC-coating significantly reduced the cytotoxicity of NZVI towards Echerichia coli.•The Ca2+ can either increase or decrease the cytotoxicity of NZVI and CMC-NZVI.•The cytotoxicity of NZVI and CMC-NZVI significantly decreased after aging.•The mechanisms related to the particle stabilization and toxicity were discussed.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
In this work, the key role of colloid chemistry in the development of novel processing routes for ceramic manufacture is reported. An overview of the origins of a ceramic processing science is ...presented, emphasizing the pioneering works and the scientific fundaments of all processing steps that make use of suspensions. A brief review of the importance of colloid chemistry in the synthesis of nanoparticles with controlled purity, size and shape is given, followed by a description of the suspension properties and their effect in the beneficiation and shaping of ceramics. The main shaping techniques for the production of bulk parts, substrates and coatings and layered ceramics are shown, as well as the multiple possibilities for the design of composites with tailored microstructures and microarchitectures.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The increasing need for drug delivery systems that improve specificity and activity and at the same time reduce toxicity to ensure maximum treatment safety has led to the development of a great ...variety of drug vectors. Carriers based on soft matter have particularly interesting characteristics. Herein we present the current standing of the research in this area, and focus on two main families, namely matrix systems and vesicles. We outline the structure, properties, and potential applications of these vectors, and discuss their main advantages and drawbacks in their synthesis.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Microrheological study of complex fluids traces its roots to the work of the botanist Robert Brown in the early nineteenth century. Indeed, passive microrheology and Brownian motion are one and the ...same. Once thought to reveal a fundamental life force, the phenomenon was ultimately leveraged by Einstein in proof of the atomic nature of matter (
Haw 2006
). His work simultaneously paved the way for modern-day passive microrheology by connecting observable particle motion-diffusion-to solvent properties-the viscosity-via the well-known Stokes-Einstein relation. Advances in microscopy techniques in the last two decades have prompted extensions of the original model to generalized forms for passive probing of complex fluids. In the last decade, active microrheology has emerged as a means by which to interrogate the nonequilibrium behavior of complex fluids, in particular, the non-Newtonian rheology of dynamically heterogeneous and microscopically small systems. Here we review theoretical and computational approaches and advances in both passive and active microrheology, with a focus on the extent to which these techniques preserve the connection between single-particle motion and flow properties, as well as the rather surprising recovery of non-Newtonian flow behavior observed in bulk rheology.
The effects of graphene oxide (GO) on the transport and deposition behaviors of colloids with different sizes in packed quartz sand were investigated in both NaCl (10 and 50 mM) and CaCl2 solutions ...(1 and 5 mM) at pH 6. Fluorescent carboxylate-modified polystyrene latex microspheres (CMLs) with size ranging from 0.2 to 2 μm were utilized as model colloids. Both breakthrough curves and retained profiles of colloids in the presence and absence of GO in suspensions under all examined solution conditions were analyzed. The breakthrough curves of all three different-sized CMLs with GO were higher yet the retained profiles were lower than those without GO at both examined ionic strengths in NaCl solutions. The observation showed that GO increased the transport and decreased the deposition of all three different-sized CMLs in NaCl solutions. However, in CaCl2 solutions, opposite observation was achieved at two different ionic strength conditions. Specifically, the presence of GO increased the transport and decreased the deposition of all three different-sized CMLs in 1 mM CaCl2 solutions, whereas, it decreased the transport and increased the deposition of all three different-sized CMLs in 5 mM CaCl2 solutions. Comparison the breakthrough curves and retained profiles of CMLs versus those of GO yielded that the overall transport and deposition behaviors of all three different-sized CMLs with GO copresent in suspensions agreed well with the transport and deposition behaviors of GO under all examined conditions. The transport and deposition behaviors of CMLs in packed porous media clearly were controlled by those of GO under the conditions investigated in present study due to the adsorption of CMLs onto GO surfaces. Our study showed that once released into natural environment, GO would adsorb (interact with) different types of colloids and thus have significant influence on the fate and transport of colloids in porous media.
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•The transport of CMLs in quartz sand was affected by GO present in suspensions.•GO increased all three sized CMLs transport in quartz sand in NaCl solutions.•GO had opposite effects on CMLs transport at low and high IS in CaCl2 solutions.•Adsorption of CMLs onto GO surfaces led to altered transport of CMLs.
The transport and deposition behaviors of all three different-sized colloids in packed porous media were significantly affected by graphene oxide.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Despite the possible occurrence of metal nanoparticles in the environment due to the discharge of engineered nanoparticles and the natural transformation of metal ions into metal nanoparticles, ...little is known about the transformation mechanism, fates, behaviors, and effects of these nanoparticles in the environment. Here, we show that dissolved organic matter (DOM) in environmental waters can mediate the reduction of ionic Ag and Au to their metallic nanoparticles under natural sunlight, suggesting that this process may be general for metals with high reduction potential. We demonstrated that the reduction was mediated by superoxide from photoirradiation of the phenol group in DOM, and the dissolved O2 significantly enhanced the formation of Ag nanoparticles. These results imply that previous knowledge about O2-induced dissolution and its effect on persistence of Ag nanoparticles should be reconsidered in a sunlit DOM-rich aqueous environment. This study can also shed light on understanding possible natural sources of Ag and Au nanoparticles in the aquatic environment, which is possibly critical in the supergene enrichment of Ag and Au.
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IJS, KILJ, NUK, PNG, UL, UM
The rise of intelligent matter Kaspar, C; Ravoo, B J; van der Wiel, W G ...
Nature (London),
06/2021, Volume:
594, Issue:
7863
Journal Article
Peer reviewed
Open access
Artificial intelligence (AI) is accelerating the development of unconventional computing paradigms inspired by the abilities and energy efficiency of the brain. The human brain excels especially in ...computationally intensive cognitive tasks, such as pattern recognition and classification. A long-term goal is de-centralized neuromorphic computing, relying on a network of distributed cores to mimic the massive parallelism of the brain, thus rigorously following a nature-inspired approach for information processing. Through the gradual transformation of interconnected computing blocks into continuous computing tissue, the development of advanced forms of matter exhibiting basic features of intelligence can be envisioned, able to learn and process information in a delocalized manner. Such intelligent matter would interact with the environment by receiving and responding to external stimuli, while internally adapting its structure to enable the distribution and storage (as memory) of information. We review progress towards implementations of intelligent matter using molecular systems, soft materials or solid-state materials, with respect to applications in soft robotics, the development of adaptive artificial skins and distributed neuromorphic computing.
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GEOZS, IJS, IMTLJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBMB, UL, UM, UPUK, ZAGLJ
We present a general theory for determining the force (and torque) exerted on a boundary (or body) in active matter. The theory extends the description of passive Brownian colloids to self-propelled ...active particles and applies for all ratios of the thermal energy
$k_{B}T$
to the swimmer’s activity
$k_{s}T_{s}={\it\zeta}U_{0}^{2}{\it\tau}_{R}/6$
, where
${\it\zeta}$
is the Stokes drag coefficient,
$U_{0}$
is the swim speed and
${\it\tau}_{R}$
is the reorientation time of the active particles. The theory, which is valid on all length and time scales, has a natural microscopic length scale over which concentration and orientation distributions are confined near boundaries, but the microscopic length does not appear in the force. The swim pressure emerges naturally and dominates the behaviour when the boundary size is large compared to the swimmer’s run length
$\ell =U_{0}{\it\tau}_{R}$
. The theory is used to predict the motion of bodies of all sizes immersed in active matter.
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