Artigos de revistas: "Colloid and Surface Chemistry"

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Amézaga González, María Fernanda, Jazzely Acosta Bezada, Víctor Gómez Flores, Christian Chapa González, Jose Rurik Farias Mancilla, S. J. Castillo, Carlos Avila Orta e Perla E. García-Casillas. "Effect of Physiological Fluid on the Photothermal Properties of Gold Nanostructured". International Journal of Molecular Sciences 24, n.º 9 (6 de maio de 2023): 8339. http://dx.doi.org/10.3390/ijms24098339.

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Colloidal gold particles have been extensively studied for their potential in hyperthermia treatment due to their ability to become excited in the presence of an external laser. However, their light-to-heat efficiency is affected by the physiologic environment. In this study, we aimed to evaluate the ability of gold sphere, rod, and star-shaped colloids to elevate the temperature of blood plasma and breast cancer-simulated fluid under laser stimulation. Additionally, the dependence of optical properties and colloid stability of gold nanostructures with physiological medium, particle shape, and coating was determined. The light-to-heat efficiency of the gold particle is shape-dependent. The light-to-heat conversion efficiency of a star-shaped colloid is 36% higher than that of sphere-shaped colloids. However, the raised temperature of the surrounding medium is the lowest in the star-shaped colloid. When gold nanostructures are exited with a laser stimulation in a physiological fluid, the ions/cations attach to the surface of the gold particles, resulting in colloidal instability, which limits electron oscillation and diminishes the energy generated by the plasmonic excitation. Fluorescein (Fl) and polyethylene glycol (PEG) attached to gold spheres enhances their colloidal stability and light-to-heat efficiency; post-treatment, they remand their optical properties.

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Čermáková, Kateřina, Ondřej Šesták, Pavel Matějka, Vladimír Baumruk e Blanka Vlčková. "Surface-Enhanced Raman Scattering (SERS) Spectroscopy with Borohydride-Reduced Silver Colloids: Controlling Adsorption of the Scattering Species by Surface Potential of Silver Colloid". Collection of Czechoslovak Chemical Communications 58, n.º 11 (1993): 2682–94. http://dx.doi.org/10.1135/cccc19932682.

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Formation of Ag colloid/adsorbate SERS-active systems (upon adsorption of the selected adsorbates on the surface of Ag colloidal particles) as a function of (i) NaBH4 to AgNO3 molar ratio in the preparation protocol of Ag colloid, and (ii) aging of the colloid has been investigated by Surface-enhanced Raman scattering (SERS) spectroscopy. Oligomeric synthetic polypeptides, bovine serum albumin, phosphate coadsorbed with CuTMePyP [copper(II) derivative of 5,10,15,20-tetrakis-(N-methylpyridinium-4-yl)porphyrin chloride] and borates in systems with N-containing bases were selected as model adsorbates. Both (i) a decrease of NaBH4 to AgNO3 molar ratio upon preparation and (ii) aging of Ag colloid affect adsorption of the adsorbates and consequently, their SERS spectra, in the same manner. Aging of Ag colloid is thus viewed as a slow hydrolysis of BH4- anions. The actual concentration of BH4- in the system is identified as the most important factor controlling adsorption of all the selected adsorbates on the surface of Ag colloid. As this factor can be related to the surface potential, the conditions controlling adsorption of the selected adsorbates are specified in terms of a more negative and/or more positive surface potential of Ag colloidal particles. A more positive surface potential promotes adsorption of polypeptides, bovine serum albumin and phosphate while observation of spectral features of borates in the SERS spectra of N-containing bases in alkaline solutions is conditioned by a more negative surface potential.

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Pietrowski, Mariusz, Michał Zieliński e Maria Wojciechowska. "Nanocolloidal Ru/MgF2 Catalyst for Hydrogenation of Chloronitrobenzene and Toluene". Polish Journal of Chemical Technology 16, n.º 2 (26 de junho de 2014): 63–68. http://dx.doi.org/10.2478/pjct-2014-0031.

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Abstract The use of magnesium fluoride support for ruthenium active phase allowed obtaining new catalysts of high activities in the hydrogenation of toluene and ortho-chloronitrobenzene. Ruthenium colloid catalysts (1 wt.% of Ru) were prepared by impregnation of the support with the earlier produced polyvinylpyrrolidone (PVP)-stabilized ruthenium colloids. The performances of the colloidal catalysts and those obtained by traditional impregnation were tested in the reactions of toluene hydrogenation to methylcyclohexane and selective hydrogenation of ortho-chloronitrobenzene (o-CNB) to ortho-chloroaniline (o-CAN). It was shown that the use of chemical reduction method allows obtaining highly monodisperse ruthenium nanoparticles of 1.6–2.6 nm in size. After reduction in hydrogen at 400oC, the colloidal ruthenium nanoparticles were found to strongly interact with MgF2 surface (SMSI), which decreased the catalyst ability to hydrogen chemisorption, but despite this, the colloid catalysts showed higher activity in o-CNB hydrogenation and higher selectivity to o-CAN than the traditional ones. It is supposed that their higher activity can be a result of high dispersion of Ru in colloid catalysts and the higher selectivity can be a consequence of the lower availability of hydrogen on the surface.

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Chrzastowski, Tina. "Information Sources in Surface and Colloid Chemistry". Science & Technology Libraries 9, n.º 3 (11 de julho de 1989): 75–96. http://dx.doi.org/10.1300/j122v09n03_09.

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Kerker, Milton. "Eighteen years of colloid and surface chemistry". Journal of Colloid and Interface Science 150, n.º 2 (maio de 1992): 599. http://dx.doi.org/10.1016/0021-9797(92)90230-j.

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Wang, Xiaolu, Martin In, Christophe Blanc, Paolo Malgaretti, Maurizio Nobili e Antonio Stocco. "Wetting and orientation of catalytic Janus colloids at the surface of water". Faraday Discussions 191 (2016): 305–24. http://dx.doi.org/10.1039/c6fd00025h.

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Janus colloidal particles show remarkable properties in terms of surface activity, self-assembly and wetting. Moreover they can perform autonomous motion if they can chemically react with the liquid in which they are immersed. In order to understand the self-propelled motion of catalytic Janus colloids at the air–water interface, wetting and the orientation of the catalytic surface are important properties to be investigated. Wetting plays a central role in active motion since it determines the contact between the fuel and the catalytic surface as well as the efficiency of the transduction of the chemical reaction into motion. Active motion is not expected to occur either when the catalytic face is completely out of the aqueous phase or when the Janus boundaries are parallel to the interfacial plane. The design of a Janus colloid possessing two hydrophilic faces is required to allow the catalytic face to react with the fuel (e.g. H₂O₂ for platinum) in water and to permit some rotational freedom of the Janus colloid in order to generate propulsion parallel to the interfacial plane. Here, we discuss some theoretical aspects that should be accounted for when studying Janus colloids at the surface of water. The free energy of ideal Janus colloidal particles at the interface is modeled as a function of the immersion depth and the particle orientation. Analytical expressions of the energy profiles are established. Energetic aspects are then discussed in relation to the particle’s ability to rotate at the interface. By introducing contact angle hysteresis we describe how the effects of contact line pinning modifies the scenario described in the ideal case. Experimental observations of the contact angle hysteresis of Janus colloids at the interface reveal the effect of pinning; and orientations of silica particles half covered with a platinum layer at the interface do not comply with the ideal scenarios. Experimental observations suggest that Janus colloids at the fluid interface behave as a kinetically driven system, where the contact line motion over the defects decorating the Janus faces rules the orientation and rotational diffusion of the particle.

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Zuo, Rui, Kexue Han, Rongtao Shi, Fei Ding, Li Liu, Jinsheng Wang, Yanguo Teng, Jie Yang e Xin Liu. "Effect of Colloidal Silicate on the Migration Behaviour of Strontium in Groundwater Environment of Geological Disposal Candidate Site". Journal of Chemistry 2019 (23 de setembro de 2019): 1–11. http://dx.doi.org/10.1155/2019/9606121.

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Various colloids are present in the natural groundwater environment, and colloids act on the processes involved when radionuclides leak from a repository in a high-level waste disposal site. This paper investigates the effect of colloidal silicate in natural groundwater environments on the migration behaviour of Sr(II). Three different experimental cases have been designed: (1) effect in the presence of colloidal silicate, (2) effect in the presence of a porous medium, and (3) effect in the presence of both colloidal silicate and porous medium (referred to as CS, PM, and PC, respectively). Batch experiments were used to study the effect of influencing factors on Sr(II) migration behaviour, such as the amount of CS, solid-to-liquid ratio, pH, contact time, and initial concentration of Sr(II). The experiments showed that the effect of PC on the migration behaviour of Sr(II) was greatest, and the presence of CS enhanced the sorption. The colloid amount, pH, and solid-to-liquid ratio significantly affected the migration behaviour. The more the colloids were added, the better the adsorption effect. The optimal pH and solid-to-liquid ratio were 6 and 20 : 1, respectively. The alkaline environment is more conductive to colloid sorption. When the solid-to-liquid ratio was 20 : 1, the sorption percentage of PC is 0.5 times larger than PM. Although the PC has a longer adsorption equilibrium time, the percentage of adsorption can be larger than that in the other two cases. The kinetics and isotherms of Sr(II) were best described by the pseudo-second-order and Langmuir models. It was inferred that strong chemical interactions and/or surface complexation contributed primarily to Sr(II) sorption, and the process was on the monolayer adsorption of the outer surface. These findings provide valuable information for the migration behaviour of strontium in groundwater environments of geological disposal site. At the same time, it provides information for the implementation of permeable reactive barrier technology to control the transport of radioactive Sr(II) and its species in natural surface and groundwater.

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Yu, Xiang, e P. Somasundaran. "Colloid Chemistry in Mineral Processing". Colloids and Surfaces A: Physicochemical and Engineering Aspects 83, n.º 2 (março de 1994): 183–84. http://dx.doi.org/10.1016/0927-7757(94)80103-7.

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Shaw, D. J., e Bernard Costello. "Introduction to colloid and surface chemistry (4th edition)". Tribology International 26, n.º 3 (junho de 1993): 222. http://dx.doi.org/10.1016/0301-679x(93)90102-7.

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Tadros, Th F. "Surface and colloid chemistry in advanced ceramics processing". Advances in Colloid and Interface Science 61 (1995): 192–93. http://dx.doi.org/10.1016/0001-8686(95)90003-9.

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Zhang, Xiao Lin, e Qing Han. "Study on the Colloid Chemistry Behavior in Domestic Old Book Paper (DOBP) Deinking System". Advanced Materials Research 236-238 (maio de 2011): 1463–66. http://dx.doi.org/10.4028/www.scientific.net/amr.236-238.1463.

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In this paper, the domestic old book paper(DOBP) was subjected to deinking process. Surface and colloid characterisitics of DOBP deinking pulp(DIP) system was investigated. The relation between surface and colloid characterisitic changes and efficiency of deinking (brightness and residual ink particles content) was studied. Technical conditions that affect the deinking pulp’s colloid chemical behavior were also analyzed here.The results showed that colloid-chemical behavior of DOBP deinking system could be changed during the deinking process. The colloid-chemical behavior, such as Zeta potential and surface tention, had a certain corresponding relation with deinking efficiency of DOBP deinking system. When Zeta potential of the deinking system was more great, and surface tension was more low in a certain range(Zeta potential was -17.0~ -16.0mV and surface tension was 59.0~61.0mN/m), brightness and ink removal efficiency of DOBP will be improved.

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Li, Runwei, Changfu Wei, Hefa Cheng e Gang Chen. "Adhesion of Colloids and Bacteria to Porous Media: A Critical Review". Reviews of Adhesion and Adhesives 7, n.º 4 (1 de dezembro de 2019): 417–60. http://dx.doi.org/10.7569/raa.2019.097314.

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Adhesion of colloids and bacteria to various surfaces is important for a variety of environmental phenomena including microbial biofouling and contamination prevention. Under saturated conditions, both colloids and bacteria have the opportunity to attach to porous medium surfaces. Under water unsaturated conditions or in the presence of the air-water interface, besides the porous medium surfaces, colloids and bacteria can also attach to the air-water interface, including the air-water-solid threephase interface. The magnitudes of adhesion of colloids and bacteria are correlated to the interactions of the colloids and bacteria with the surfaces, which are a function of their surface physicochemical properties. In this review, adhesion theories are revisited and adhesion of colloids and bacteria to porous media and the air-water interface is discussed. The interaction forces are quantified using various theoretical models including the DLVO models and used to interpret related adhesion. The impact of surfactants on colloid and bacterial adhesion is also discussed. The review also includes the implementation of the adhesion theory in interpreting colloid and bacterial fate and transport in the subsurface soil.

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Yokoyama, Kazushige, Kieran Brown, Peter Shevlin, Jack Jenkins, Elizabeth D’Ambrosio, Nicole Ralbovsky, Jessica Battaglia, Ishan Deshmukh e Akane Ichiki. "Examination of Adsorption Orientation of Amyloidogenic Peptides Over Nano-Gold Colloidal Particle Surfaces". International Journal of Molecular Sciences 20, n.º 21 (28 de outubro de 2019): 5354. http://dx.doi.org/10.3390/ijms20215354.

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The adsorption of amyloidogenic peptides, amyloid beta 1–40 (Aβ1–40), alpha-synuclein (α-syn), and beta 2 microglobulin (β2m), was attempted over the surface of nano-gold colloidal particles, ranging from d = 10 to 100 nm in diameter (d). The spectroscopic inspection between pH 2 and pH 12 successfully extracted the critical pH point (pHo) at which the color change of the amyloidogenic peptide-coated nano-gold colloids occurred due to aggregation of the nano-gold colloids. The change in surface property caused by the degree of peptide coverage was hypothesized to reflect the ΔpHo, which is the difference in pHo between bare gold colloids and peptide coated gold colloids. The coverage ratio (Θ) for all amyloidogenic peptides over gold colloid of different sizes was extracted by assuming Θ = 0 at ΔpHo = 0. Remarkably, Θ was found to have a nano-gold colloidal size dependence, however, this nano-size dependence was not simply correlated with d. The geometric analysis and simulation of reproducing Θ was conducted by assuming a prolate shape of all amyloidogenic peptides. The simulation concluded that a spiking-out orientation of a prolate was required in order to reproduce the extracted Θ. The involvement of a secondary layer was suggested; this secondary layer was considered to be due to the networking of the peptides. An extracted average distance of networking between adjacent gold colloids supports the binding of peptides as if they are “entangled” and enclosed in an interfacial distance that was found to be approximately 2 nm. The complex nano-size dependence of Θ was explained by available spacing between adjacent prolates. When the secondary layer was formed, Aβ1–40 and α-syn possessed a higher affinity to a partially negative nano-gold colloidal surface. However, β2m peptides tend to interact with each other. This difference was explained by the difference in partial charge distribution over a monomer. Both Aβ1–40 and α-syn are considered to have a partial charge (especially δ+) distribution centering around the prolate axis. The β2m, however, possesses a distorted charge distribution. For a lower Θ (i.e., Θ <0.5), a prolate was assumed to conduct a gyration motion, maintaining the spiking-out orientation to fill in the unoccupied space with a tilting angle ranging between 5° and 58° depending on the nano-scale and peptide coated to the gold colloid.

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Ogata, Naoya. "Surface and Colloid Science". Angewandte Chemie International Edition in English 27, n.º 11 (novembro de 1988): 1584–85. http://dx.doi.org/10.1002/anie.198815841.

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Schmid, Günter, Andreas Lehnert, Ulrich Kreibig, Zbignew Adamczyk e Peter Belouschek. "Synthese und elektronenmikroskopische Untersuchung kontrolliert gewachsener, ligandstabilisierter Goldkolloide sowie theoretische Überlegungen zur Oberflächenbelegung durch Kolloide / Synthesis and Electron Microscopic Investigation of Controlled Grown, Ligand Stabilized Gold Colloids and Theoretical Considerations on the Covering of Surfaces by Colloids". Zeitschrift für Naturforschung B 45, n.º 7 (1 de julho de 1990): 989–94. http://dx.doi.org/10.1515/znb-1990-0713.

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18 nm Gold colloids are used as seeds for a controlled growth of 36 nm colloids which are then stabilized by P(m-C6H4SO3Na)3. These colloids can be isolated as golden leaflets and are readily soluble in water in virtually any concentration. Electron microscopic investigations prove a very small particle size distribution. X-ray powder diffraction and molecular weight determinations support the results of the electron microscopic investigations. The distance between the colloidal particles in two-dimensional layers corresponds to double-layers of phosphane ligands around each colloid, twice 1.2 nm. Isolated colloids seem to possess thicker ligand shells. A single 44 nm colloid shows a corona of about 7.2 nm thickness, corresponding to 12 phosphane layers. A quantitative description of two-dimensional packing densities is suggested using a novel theoretical model. By means of Monte Carlo simulations the two-dimensional structures are formed during the covering of supports of different geometry can be calculated.

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Song, Xiao Zong, Yong Zhang e Fei Hu Zhang. "Study on Removal Mechanism of Nanoparticle Colloid Jet Machining". Advanced Materials Research 53-54 (julho de 2008): 363–68. http://dx.doi.org/10.4028/www.scientific.net/amr.53-54.363.

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We developed a nanoparticle colloid jet machining to fulfill the requirement for ultrasmooth surface in terms of the studying on micro structure of work surface, the high surface energy and intense adsorption of SiO2 nanoparticle. In this paper, three types impact in nanoparticle colloid jet machining have been analysed and the atom removing model has been founded based on the physical chemistry theory of solid surface and interface. The factors which may influence the nanoparticle colloid jet machining quality (such as the diameter of nanoparticle, colloid jet velocity and dynamical viscidity) have been studied to provide theoretical support for further studying in nanoparticle colloid jet machining.

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Goel, Alok, e Johannes Lützenkirchen. "Relevance of Colloid Inherent Salt Estimated by Surface Complexation Modeling of Surface Charge Densities for Different Silica Colloids". Colloids and Interfaces 6, n.º 2 (6 de abril de 2022): 23. http://dx.doi.org/10.3390/colloids6020023.

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Potentiometric titrations have been routinely used to measure the proton-related surface charge density (SCD) of particles in solution. Here, we quantify the SCD of silica nanoparticles (NPs) that are commercially available as charge-stabilized colloids (by the addition of NaOH) in the presence of known amounts of added NaCl. The experimental results are simulated by surface complexation models (SCMs) of the electrical double layer (EDL). The modeling results suggest that involving only the added NaCl electrolyte yields poor agreement between the experiment and the best achievable fit. An increase in the Na concentration accounting for the colloid inherent salt (CIS) associated with these charge-stabilized colloids results in much better simulations. In the available literature, this CIS has often been disregarded. However, in the modeling, the total concentration of Na must be known for a consistent mole balance and derivation of reliable ion-pair binding constants. If the CIS is not accounted for or the original suspensions are not dialyzed, the presence of CIS renders the study of those colloids difficult, particularly when investigating specific ion effects, since the CIS always interferes. In the present work, we show that the SCM-estimated amount of CIS from varying the total salt and solid concentration agrees surprisingly well with the manufacturer specification.

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Lozovski, V. Z., A. G. Vasiljev, T. A. Vasyliev, I. S. Petrik, A. M. Eremenko e N. P. Rybalchenko. "Resonance properties of the solution of quercetin stabilized silver nanoparticles in a nutrient medium". Himia, Fizika ta Tehnologia Poverhni 15, n.º 1 (30 de março de 2024): 86–93. http://dx.doi.org/10.15407/hftp15.01.086.

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Changes in the light absorption spectrum when mixing colloids of Ag nanoparticles with a diameter of 7 nm in a quercetin shell with a nutrient medium were studied in the present article. Colloids of silver nanoparticles were prepared by chemical reduction of AgNO3 silver salt with sodium tetrahydroborate (NaBH4) in an aqueous solution. Quercetin is a flavonoid of plant origin. It was chosen to stabilize nanoparticles due to its capability to form complexes with metals. The quercetin shell is capable to preserve the bactericidal effect of silver NPs on bacteria and weaken their toxic effect on healthy cells of the human body. The absorption spectra of solutions from which nanoparticle colloids were synthesized were used to control the synthesis result. The Luria-Bertani nutrient medium was studied in the work. Absorption spectra of the nutrient medium and nanoparticle colloids were again obtained immediately before mixing. Then, the nutrient medium and the nanoparticle colloid were mixed in volume proportion 1:1, and the absorption spectrum of the mixture was mesured. The absorption spectrum of the mixture did not reproduce a simple overlay of the nanoparticle colloid spectrum on the absorption spectrum of the nutrient medium. To describe the experimental spectra, a colloid of stabilized silver nanoparticles, a nutrient medium, and a mixture of a colloid and a nutrient medium were considered by nanocomposites of various organic and inorganic nanoparticles in a liquid. As a result, experimental absorption spectra were theoretically approximated by related to these nanoparticles elementary oscillators. The error of the discrepancy between experimental and simulated spectra did not exceed 3%. Analysis of the complex spectra of the mixture of the nanoparticle colloid and the nutrient medium has shown that the frequency of the localized plasmon resonance in the nanoparticles most likely does not change. It means that for studying the effect of nanoparticles on biological objects (microbes or viruses), the wavelength of external irradiation must be chosen equal to the wavelength of LPR in the colloid.

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Krott, Leandro B., e José Rafael Bordin. "How Dimensionality Affects the Structural Anomaly in a Core-Softened Colloid". Colloids and Interfaces 7, n.º 2 (21 de abril de 2023): 33. http://dx.doi.org/10.3390/colloids7020033.

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The interaction between hard core–soft shell colloids are characterized by having two characteristic distances: one associated with the penetrable, soft corona and another one corresponding to the impenetrable core. Isotropic core-softened potentials with two characteristic length scales have long been applied to understand the properties of such colloids. Those potentials usually show water-like anomalies, and recent findings have indicated the existence of multiple anomalous regions in the 2D limit under compression, while in 3D, only one anomalous region is observed. In this direction, we perform molecular dynamics simulations to unveil the details about the structural behavior in the quasi-2D limit of a core-softened colloid. The fluid was confined between highly repulsive solvophobic walls, and the behavior at distinct wall separations and colloid densities was analyzed. Our results indicated a straight relation between the 2D- or 3D-like behavior and layer separation. We can relate that if the system behaves as independent 2D-layers, it will have a 2D-like behavior. However, for some separations, the layers are connected, with colloids hopping from one layer to another, thus having a 3D-like structural behavior. These findings fill the gap in the depiction of the anomalous behavior from 2D to 3D.

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Roto, Roto, Hani Prima Rasydta, Adhitasari Suratman e Nurul Hidayat Aprilita. "Effect of Reducing Agents on Physical and Chemical Properties of Silver Nanoparticles". Indonesian Journal of Chemistry 18, n.º 4 (12 de novembro de 2018): 614. http://dx.doi.org/10.22146/ijc.26907.

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Silver nanoparticles having uniform size and shape, a diameter range of 10–50 nm, excellent stability, and high zeta potential are always desirable for many applications. The silver nanoparticles were synthesized by chemical reduction method using some reducing agents in a polyvinyl alcohol solution. This study aims at determining the effect of reducing agents on the chemical and physical properties of silver nanoparticles. Ascorbic acid, sodium borohydride, hydrazine, sodium citrate, and glucose were used as reducing agents. Surface Plasmon Resonance (SPR) absorbance, morphology, zeta potential, crystal system, and stability of the products were studied. The results showed that the chemical and physical properties of the colloidal Ag nanoparticles were dependent on the reducing agents. In general, the produced silver nanoparticles have an fcc crystal system with a unit cell of 4.0906–4.0992 Å. The SPR absorbance of the colloids has the peak in the range of 401–433 nm. We found that the colloid of silver nanoparticles prepared by using ascorbic acid has uniform spherical shape, the diameter of about 20 nm, and zeta potential of -10.4 mV. After being stored for one month, the SPR absorbance of the colloid decreased by only 5%. This type of colloidal Ag nanoparticles prepared by using ascorbic acid is expected to be used for chemical sensors, an antibacterial agent, and so on.

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Ahmadi-Sénichault, A., V. Canseco, N. Sefrioui-Chaibainou, A. Omari e H. Bertin. "Displacement of Colloidal Dispersions in Porous Media: Experimental & Numerical Approaches". Diffusion Foundations 7 (junho de 2016): 53–68. http://dx.doi.org/10.4028/www.scientific.net/df.7.53.

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The main objective of this paper is to give more insight on colloids deposition and re-entrainment in presence of a rough surface. Experiments on retention and release of colloids in a porous medium are first presented. The influence of physicochemical and hydrodynamic conditions is investigated. The experimental results cannot be qualitatively interpreted using the DLVO theory and knowledges at pore scale are then needed. A 3D numerical simulation approach at the pore scale is therefore proposed where the motion of colloids is solved in presence of collector surfaces bearing various kinds of asperities and by taking into account physico-chemical interactions calculated at each time step during colloid movement. It is obviously observed that both deposition and mobilization of particles are dependent on solution chemistry and hydrodynamic conditions and are significantly affected by the form and size of the local roughness of the pore surface. Therefore, depending on solution ionic strength and surface topography, colloids may be adsorbed or not and when a particle is retained an increase of flow strength is then needed to remove it and such an increase is specific to the location of occurrence of the adsorption step. In general, simulation results allow us to explain our experimental results that show that by steeply increasing the flow strength, more and more fractions of particles retained inside the porous medium are released until all particles are removed.

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Aveyard, R., B. P. Binks, J. Chen, J. Esquena, P. D. I. Fletcher, R. Buscall e S. Davies. "Surface and Colloid Chemistry of Systems Containing Pure Sugar Surfactant". Langmuir 14, n.º 17 (agosto de 1998): 4699–709. http://dx.doi.org/10.1021/la980519x.

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Thurman, E. M. "Surface and colloid chemistry in natural waters and water treatment". Chemical Geology 95, n.º 3-4 (fevereiro de 1992): 362–63. http://dx.doi.org/10.1016/0009-2541(92)90023-x.

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Biggs, Simon. "Handbook of Applied Surface and Colloid Chemistry. (Ed K. Holmberg)". Australian Journal of Chemistry 55, n.º 3 (2002): 237. http://dx.doi.org/10.1071/chv55n3_br.

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Ramsey, John D. F. "Extended Summaries— SCI Colloid and Surface Chemistry Group Meeting. Introduction." Journal of Chemical Technology & Biotechnology 65, n.º 4 (abril de 1996): 385. http://dx.doi.org/10.1002/(sici)1097-4660(199604)65:4<385::aid-jctb419>3.0.co;2-m.

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Kerker, Milton. "Surface and colloid science". Journal of Colloid and Interface Science 107, n.º 2 (outubro de 1985): 589. http://dx.doi.org/10.1016/0021-9797(85)90219-x.

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Amadu, Mumuni, e Adango Miadonye. "Determination of the Point of Zero Charge pH of Borosilicate Glass Surface Using Capillary Imbibition Method". International Journal of Chemistry 9, n.º 3 (25 de junho de 2017): 67. http://dx.doi.org/10.5539/ijc.v9n3p67.

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The point of zero charge pH of an oxide surface is a fundamental surface chemistry property or solids or metal oxides that determine the nature of interaction at the solid-aqueous solution interface. In colloid chemistry this physical parameter controls the evolution of the electric double layer as well as adsorption and desorption processes.In colloid chemistry a number of methods have been used for the determination of the point of zero charge pH of an oxide surface. This ranges from titrimetric to radiation chemistry approach that deals with scanning electron microscopy.In this study, the direct effect of aqueous solution acidity on the solid-liquid interfacial free energy and the consequence of this effect on spontaneous imbibition of aqueous solution into borosilicate glass have been exploited for the determination of the point of zero charge pH of this type of glass. What is new in this method is that while the traditional titration method relies on neutralization of surface charges, the present method relies on interfacial free energy changes due to aqueous solution pH changes and the effect of this on the wettability of borosilcate glass surface. Result of point of zero charge pH obtained from the present method has been compared with those obtained using traditional methods. The comparison shows close agreements and this proves the technique used in the present work as a novel method for the determination of the point of zero charge pH of oxide surfaces.

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Moreels, Iwan, Bernd Fritzinger, José C. Martins e Zeger Hens. "Surface Chemistry of Colloidal PbSe Nanocrystals". Journal of the American Chemical Society 130, n.º 45 (12 de novembro de 2008): 15081–86. http://dx.doi.org/10.1021/ja803994m.

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De Corato, Marco, e Ignacio Pagonabarraga. "Onsager reciprocal relations and chemo-mechanical coupling for chemically active colloids". Journal of Chemical Physics 157, n.º 8 (28 de agosto de 2022): 084901. http://dx.doi.org/10.1063/5.0098425.

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Similar to cells, bacteria, and other micro-organisms, synthetic chemically active colloids can harness the energy from their environment through a surface chemical reaction and use the energy to self-propel in fluidic environments. In this paper, we study the chemo-mechanical coupling that leads to the self-propulsion of chemically active colloids. The coupling between chemical reactions and momentum transport is a consequence of Onsager reciprocal relations. They state that the velocity and the surface reaction rate are related to mechanical and chemical affinities through a symmetric matrix. A consequence of Onsager reciprocal relations is that if a chemical reaction drives the motion of the colloid, then an external force generates a reaction rate. Here, we investigate Onsager reciprocal relations for a spherical active colloid that catalyzes a reversible surface chemical reaction between two species. We solve the relevant transport equations using a perturbation expansion and numerical simulations to demonstrate the validity of reciprocal relations around the equilibrium. Our results are consistent with previous studies and highlight the key role of solute advection in preserving the symmetry of the Onsager matrix. Finally, we show that Onsager reciprocal relations break down around a nonequilibrium steady state, which has implications for the thermal fluctuations of the active colloids used in experiments.

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Barišić, Antun, Johannes Lützenkirchen, Nikol Bebić, Qinzhi Li, Khalil Hanna, Andrey Shchukarev e Tajana Begović. "Experimental Data Contributing to the Elusive Surface Charge of Inert Materials in Contact with Aqueous Media". Colloids and Interfaces 5, n.º 1 (23 de janeiro de 2021): 6. http://dx.doi.org/10.3390/colloids5010006.

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We studied the charging of inert surfaces (polytetrafluoroethylene, i.e., PTFE; graphite; graphene; and hydrophobic silica) using classical colloid chemistry approaches. Potentiometric titrations showed that these surfaces acquired less charge from proton-related reactions than oxide minerals. The data from batch-type titrations for PTFE powder did not show an effect of ionic strength, which was also in contrast with results for classical colloids. In agreement with classical colloids, the electrokinetic results for inert surfaces showed the typical salt level dependence. In some cases, the point of zero net proton charge as determined from mass and tentatively from acid–base titration differed from isoelectric points, which has also been previously observed, for example by Chibowski and co-workers for ice electrolyte interfaces. Finally, we found no evidence for surface contaminations of our PTFE particles before and after immersion in aqueous solutions. Only in the presence of NaCl-containing solutions did cryo-XPS detect oxygen from water. We believe that our low isoelectric points for PTFE were not due to impurities. Moreover, the measured buffering at pH 3 could not be explained by sub-micromolar concentrations of contaminants. The most comprehensive explanation for the various sets of data is that hydroxide ion accumulation occurred at the interfaces between inert surfaces and aqueous solutions.

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Vargas-Baca, Ignacio, Andrew P. Brown, Mark P. Andrews, Tigran Galstian, Yuejun Li, Hojatollah Vali e Mark G. Kuzyk. "Linear and nonlinear optical responses of a dye anchored to gold nanoparticles dispersed in liquid and polymeric matrixes". Canadian Journal of Chemistry 80, n.º 11 (1 de novembro de 2002): 1625–33. http://dx.doi.org/10.1139/v02-147.

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The compound [4-CH3C6H4-SS-CH2CH2-N(CH3)C6H4C(C6H4N(CH3)2)-4)2]Cl (1a) consists of the triarylmethyl chromophore of crystal violet appended to an organic disulfide, to entail direct attachment of this dye to gold surfaces. Addition of 1a to colloidal dispersions of the metal produced a stable dispersion in methanolwater mixtures. Transmission electron microscopy of Freeze-Fracture sections shadowed with carbon and platinum confirmed that the dispersion remains unaggregated. Local-field effects and coupling to the surface plasmon of gold magnified the interaction of the chromophore with optical fields. A large oscillator strength in the visible spectrum (f ca. 35) and a first hyperpolarizability (β ca. 1026 esu, hyper-Rayleigh scattering) were observed as the colloid adsorbed dye molecules. A Hill-type analysis indicated that the adsorption process is cooperative. This combination of organic chromophore and nanoparticle was adapted for incorporation into PMMA-based composite films whose electrooptic coefficient (r113 = 2.20 pm V1) is larger than the sum of the individual contributions of dye and metallic particles.Key words: chromophores, colloids, gold, local-field effects, nonlinear optical materials.

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32

Park, Jong-Min, Chan-Woo Lee, Wan-Sul Lee, Kyung-Mo Yang, Jun-Ho Lee, Gi-Yong Nam, Seong-Hoon Lee, Yong Sang Lee, Youngkwan Lee e Jae-Do Nam. "MONTMORILLONITE-REINFORCED NATURAL RUBBER NANOCOMPOSITES THROUGH EMULSION STABILIZATION–DESTABILIZATION METHOD". Rubber Chemistry and Technology 85, n.º 2 (1 de junho de 2012): 165–79. http://dx.doi.org/10.5254/rct.12.88978.

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Abstract A nanoplatelet of montmorillonite (MMT) was incorporated in the natural rubber (NR) matrix at a high loading content using a newly developed stabilization–destabilization process in the colloid states. Examination of the surface charge of the colloid drops by zeta potential measurement led to the identification of the stable and unstable conditions of the colloid mixture as well as each colloid system as a function of pH. The stabilized mixture of the MMT and NR colloids was subsequently destabilized by changing the pH of the mixture to achieve a well-dispersed and intercalated NR/MMT precipitate. The resulting NR/MMT nanocomposites provided an exfoliated MMT morphology up to 25 phr, and the mechanical properties and aging tolerance of the resulting nanocomposite vulcanizates were substantially enhanced by the incorporated MMT nanofillers. The developed stabilization–destabilization methodology ensured a highly loaded MMT rubber composite system, which could be used to obtain high performance NR/MMT nanocomposite systems with ease without using high-shear processing techniques.

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Valentine, M. T., Z. E. Perlman, M. L. Gardel, J. H. Shin, P. Matsudaira, T. J. Mitchison e D. A. Weitz. "Colloid Surface Chemistry Critically Affects Multiple Particle Tracking Measurements of Biomaterials". Biophysical Journal 86, n.º 6 (junho de 2004): 4004–14. http://dx.doi.org/10.1529/biophysj.103.037812.

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34

Perry, Reeves B. "Principles of Colloid and Surface Chemistry, Second Edition (Hiemenz, P. C.)". Journal of Chemical Education 64, n.º 12 (dezembro de 1987): A328. http://dx.doi.org/10.1021/ed064pa328.3.

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35

Maurice, Patricia A. "Applications of atomic-force microscopy in environmental colloid and surface chemistry". Colloids and Surfaces A: Physicochemical and Engineering Aspects 107 (fevereiro de 1996): 57–75. http://dx.doi.org/10.1016/0927-7757(95)03372-6.

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Andreasson, A., B. J�nsson e B. Lindman. "Surface and colloid chemistry of peat and peat dewatering. Electrostatic effects". Colloid & Polymer Science 266, n.º 2 (fevereiro de 1988): 164–72. http://dx.doi.org/10.1007/bf01452814.

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37

Kerker, Milton. "Some historical ruminations on the ACS Colloid and Surface Chemistry Symposium". Journal of Colloid and Interface Science 291, n.º 2 (novembro de 2005): 606–9. http://dx.doi.org/10.1016/j.jcis.2005.08.036.

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38

Taylor, Spencer E. "Colloids and Interfaces in Oil Recovery". Colloids and Interfaces 3, n.º 2 (31 de maio de 2019): 50. http://dx.doi.org/10.3390/colloids3020050.

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39

Fuster, H. A., Xin Wang, Xiaoguang Wang, E. Bukusoglu, S. E. Spagnolie e N. L. Abbott. "Programming van der Waals interactions with complex symmetries into microparticles using liquid crystallinity". Science Advances 6, n.º 25 (junho de 2020): eabb1327. http://dx.doi.org/10.1126/sciadv.abb1327.

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Asymmetric interactions such as entropic (e.g., encoded by nonspherical shapes) or surface forces (e.g., encoded by patterned surface chemistry or DNA hybridization) provide access to functional states of colloidal matter, but versatile approaches for engineering asymmetric van der Waals interactions have the potential to expand further the palette of materials that can be assembled through such bottom-up processes. We show that polymerization of liquid crystal (LC) emulsions leads to compositionally homogeneous and spherical microparticles that encode van der Waals interactions with complex symmetries (e.g., quadrupolar and dipolar) that reflect the internal organization of the LC. Experiments performed using kinetically controlled probe colloid adsorption and complementary calculations support our conclusion that LC ordering can program van der Waals interactions by ~20 kBT across the surfaces of microparticles. Because diverse LC configurations can be engineered by confinement, these results provide fresh ideas for programming van der Waals interactions for assembly of soft matter.

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40

Valverde-Alva, Miguel A., Jhenry F. Agreda-Delgado, Juan A. Vega-González, Juan C. Rodríguez-Soto, Julio C. Idrogo-Córdova, Luis M. Angelats-Silva e Claver W. Aldama-Reyna. "Effect of the magnetic field on the synthesis of colloidal silver and gold nanoparticles by laser ablation in bidestilated water". MOMENTO, n.º 63 (9 de julho de 2021): 1–11. http://dx.doi.org/10.15446/mo.n63.91515.

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The effect of magnetic field of 0.3 T on the concentration, distribution of sizes in suspension and zeta potential of colloidal gold and colloidal silver nanoparticles, obtained by considering the pulsed laser ablation in double distilled water was studied. The magnetic field was transverse to the direction of incidence of the laser radiation and parallel to the surface of a submerged target. An Nd: YAG laser was used (1064 nm in wavelength, 10 ns in duration, repetition rate of 10 Hz and 37 mJ of energy) to ablate targets. The colloids were characterized by inductively coupled plasma optical emission spectroscopy, ultraviolet-visible spectroscopy, dynamic light scattering and zeta potential. Concentration analysis suggested that applying magnetic field of 0.3 T during nanoparticle synthesis leads to higher concentration. Applying magnetic field led to an eleven percent increase in the concentration of the colloid with gold nanoparticles and a five percent increase in the concentration of the colloidal silver nanoparticles. The absorption spectra suggested the presence of spherical nanoparticles. When analyzing the effect of the magnetic field on the hydrodynamic size distribution of the nanoparticles and the zeta potential of the colloids, no significant changes were evidenced. The magnetic confinement of the plasma induced by laser ablation caused changes in the characteristics of the colloids.

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41

Peula-García, J. M., R. Hidalgo-Alvarez e F. J. de las Nieves. "Colloid stability and electrokinetic characterization of polymer colloids prepared by different methods". Colloids and Surfaces A: Physicochemical and Engineering Aspects 127, n.º 1-3 (julho de 1997): 19–24. http://dx.doi.org/10.1016/s0927-7757(96)03890-3.

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Roto, Roto, Marcelina Marcelina, Nurul Hidayat Aprilita, Mudasir Mudasir, Taufik Abdillah Natsir e Bella Mellisani. "Investigation on the Effect of Addition of Fe³⁺ Ion into the Colloidal AgNPs in PVA Solution and Understanding Its Reaction Mechanism". Indonesian Journal of Chemistry 17, n.º 3 (30 de novembro de 2017): 439. http://dx.doi.org/10.22146/ijc.22695.

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Analysis of Fe3+ ion present in aqueous solutions is always of interests. Recently, this ion has been analyzed by colorimetric methods using colloid of silver nanoparticles (AgNPs) in capping agents of polymers. The reaction mechanism between AgNPs and Fe3+ is still subject to the further investigation. In this work, 1,10-phenanthroline was used to probe the reaction mechanism between AgNPs and Fe3+ ion in the solution. The colloids of AgNPs were prepared in the polyvinyl alcohol (PVA) solution and reacted with Fe3+. The colloid surface plasmon absorbance decreases linearly along with the increase in Fe3+ concentration. The addition of 1,10-phenanthroline to mixture changes the solution to red, indicating that the reaction produces Fe2+. This suggests that the reduction of the AgNPs absorbance is the result of oxidation of the Ag nanoparticles along with the reduction of Fe3+.

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43

Wolff, Thomas, e Bernhard Klaussner. "Overlap of colloid chemistry and photochemistry in surfactant systems". Advances in Colloid and Interface Science 59 (agosto de 1995): 31–94. http://dx.doi.org/10.1016/0001-8686(95)80004-m.

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Li, Ning, Chengzhi Hu, Xiaoning Fu, Xiufang Xu, Rui Liu, Huijuan Liu e Jiuhui Qu. "Identification of Al13 on the Colloid Surface Using Surface-Enhanced Raman Spectroscopy". Environmental Science & Technology 51, n.º 5 (21 de fevereiro de 2017): 2899–906. http://dx.doi.org/10.1021/acs.est.6b05721.

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45

Adachi, Kenta, Yukimasa Ura e Naoya Kanetada. "Stimuli-triggered reversible switching mechanism between H- and J-type supramolecular assemblies of cationic porphyrins adsorbed on tungsten(VI) oxide surface". Journal of Porphyrins and Phthalocyanines 22, n.º 08 (agosto de 2018): 658–69. http://dx.doi.org/10.1142/s1088424618500372.

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Supramolecular organic dye–inorganic semiconductor nanocrystal assemblies are potentially useful in a broad range of technologies and applications, including photovoltaic systems, but the molecular basis of the adsorption of dye molecules onto the semiconductor surfaces remains poorly understood. Herein, we investigated the pH-dependent adsorption and conformational change of two cationic porphyrin stereoisomers [5,10-diphenyl-15,20-di([Formula: see text]-methyl-4-pyridyl)porphyrin (cis-DMPyP) and 5,15-diphenyl-10,20-di([Formula: see text]-methyl-4-pyridyl)porphyrin (trans-DMPyP)] on the tungsten(VI) oxide (WO[Formula: see text] colloid nanoparticle in aqueous media by means of UV-vis absorption spectroscopy. In accordance with the combination of a modified Langmuir adsorption model and Kasha’s exciton coupling model, the molecular orientation and stacking arrangement of DMPyP derivatives on the WO[Formula: see text] colloid surface are discussed in detail. In the trans-DMPyP/WO[Formula: see text] aqueous system, trans-DMPyP molecules adopted flat-on orientation with respect to the WO[Formula: see text] colloid surface and eventually formed head-to-tail [Formula: see text]-dimers regardless of pH conditions. cis-DMPyP molecules in the acidic system also lay flat-on and mainly formed [Formula: see text]-dimers on the WO[Formula: see text] colloid surface, whereas ones in the neutral system exhibited a dominant edge-on orientation and had a higher tendency to form face-to-face [Formula: see text]-dimers. Additionally, we have also convincingly demonstrated the pH-triggered switchable [Formula: see text]-stacking geometry of cis-DMPyP molecules from [Formula: see text]- to [Formula: see text]-dimer and vice versa on the WO[Formula: see text] colloid surface. Such findings will undoubtedly provide a pertinent guideline for the rational design of stimuli-responsive organic-inorganic materials.

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46

Song, Xiaozong, e Gui Gao. "Removal Mechanism Investigation of Ultraviolet Induced Nanoparticle Colloid Jet Machining". Molecules 26, n.º 1 (25 de dezembro de 2020): 68. http://dx.doi.org/10.3390/molecules26010068.

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Ultraviolet induced nanoparticle colloid jet machining is a new ultra-precision machining technology utilizing the reaction between nanoparticles and the surface of the workpiece to achieve sub-nanometer ultra-smooth surface manufacturing without damage. First-principles calculations based on the density functional theory (DFT) were carried out to study the atomic material removal mechanism of nanoparticle colloid jet machining and a series of impacting and polishing experiments were conducted to verify the mechanism. New chemical bonds of Ti-O-Si were generated through the chemical adsorption between the surface adsorbed hydroxyl groups of the TiO2 cluster and the Si surface with the adsorption energy of at least −4.360 eV. The two Si-Si back bonds were broken preferentially and the Si atom was removed in the separation process of TiO2 cluster from the Si surface realizing the atomic material removal. A layer of adsorbed TiO2 nanoparticles was detected on the Si surface after 3 min of fixed-point injection of an ultraviolet induced nanoparticle colloid jet. X-ray photoelectron spectroscopy results indicated that Ti-O-Si bonds were formed between TiO2 nanoparticles and Si surface corresponding to the calculation result. An ultra-smooth Si workpiece with a roughness of Rq 0.791 nm was obtained by ultraviolet induced nanoparticle colloid jet machining.

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Jovanovic, Svetlana, Zoran Markovic, Duska Kleut, Vladimir Trajkovic, Branka Babic-Stojic, Miroslav Dramicanin e Todorovic Markovic. "Singlet oxygen generation by higher fullerene-based colloids". Journal of the Serbian Chemical Society 75, n.º 7 (2010): 965–73. http://dx.doi.org/10.2298/jsc090617062j.

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In this paper, the results of the synthesis and characterization of higher fullerene-based colloids is presented. The generation of singlet oxygen 1O2 (1?g) by fullerene water-based colloids (nC60, nC70 and nC84) was investigated. It was found by electron paramagnetic resonance spectroscopy that the generation of singlet oxygen was the highest by the nC84 colloid. The amplitude of the electron paramagnetic resonance (EPR) signal was two orders of magnitude higher than the amplitude of the EPR signals which originated from nC60 and nC70. The surface morphology and the structure of the particles of the water-based colloids were investigated by atomic force microscopy (AFM). The AFM study showed that the average size of the nC60, nC70 and nC84 were 200 nm, 80 nm and 70 nm, respectively. In addition, the particle size distribution of the nC60, nC70 and nC84 colloids was determined by dynamic light scattering (DLS) measurements.

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Nelson, E. C., e P. V. Braun. "CHEMISTRY: Enhancing Colloids Through the Surface". Science 318, n.º 5852 (9 de novembro de 2007): 924–25. http://dx.doi.org/10.1126/science.1148009.

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49

Kerker, Milton. "Dictionary of colloid and surface science". Journal of Colloid and Interface Science 140, n.º 1 (novembro de 1990): 305. http://dx.doi.org/10.1016/0021-9797(90)90350-w.

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Walsch, J., e S. Dultz. "Effects of pH, Ca- and SO4-concentration on surface charge and colloidal stability of goethite and hematite – consequences for the adsorption of anionic organic substances". Clay Minerals 45, n.º 1 (março de 2010): 1–13. http://dx.doi.org/10.1180/claymin.2010.045.1.01.

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AbstractSoil solution chemistry, especially pH and the presence of multivalent ions, affects the surface charge (SC) of Fe oxides and accordingly colloidal stability and sorption properties. The SC of synthetic goethite and hematite was quantified in the presence of different electrolytes (NaCl, CaCl2, Na2SO4and CaSO4) by combining the streaming potential with polyelectrolyte titration. The point of zero charge (PZC) for goethite was observed at pH 8.2 and the stability field around the PZC, where colloids are flocculated, is more extended (±1 pH unit) than that of hematite with a PZC at pH 7.1 (±0.5 pH unit). The SC decreases with increasing SO4concentration, indicating adsorption of SO4on the oxide, whereas the presence of Ca increases the SC. At pH 4, the addition of 0.1 mmol l–1Na2SO4induced a decrease in SC from 1.5 to 0.380 μmolcm–2for goethite and from 0.85 to 0.42 μmolcm–2for hematite. In a suspension with 0.1 mmol l–1Na2SO4, the number of colloids is already reduced, and both oxides flocculate rapidly and completely at >0.5 mmol l–1Na2SO4. While the addition of SO4did not affect charge titrations with the cationic polyelectrolyte, the anionic polyelectrolyte formed complexes with Ca, resulting in an overestimation of positive SC. The electrolyte CaSO4is most efficient at keeping goethite and hematite in the pH range 4–10 in the flocculated state. Besides pH, the presence of multivalent ions should also be considered when predicting colloid mediated transport and adsorption properties of anionic substances by Fe oxides in soil systems.

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