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Hamid Reza Rajabi, Fatemeh Karimi, Hossein Kazemdehdashti, Leila Kavoshi
In this research, a sono-assisted chemical precipitation method was developed for a quick and efficient water-based synthesis of zinc sulfide (ZnS) quantum dots (QDs), in room temperature. ZnS QDs as pure and doped with some transition metal ions (such as Cu2+ , Mn2+ , Ag+ ) were prepared in the presence of l-cysteine, as capping agent. In comparison with the previous conventional methods, applying the ultrasonic irradiation provides a significant decrease in the reaction time. In comparison with previous reported conventional chemical QD synthesis methods, the required time for a complete synthesis in the presence of ultrasonic irradiations was significantly reduced to a period as short as 15 min, in a temperature of 40 °C...
February 22, 2018: Journal of Photochemistry and Photobiology. B, Biology
Syeda Sabrina, Mykola Tasinkevych, Suzanne Ahmed, Allan M Brooks, Monica Olvera de la Cruz, Thomas E Mallouk, Kyle J M Bishop
The propulsion of micro- and nanoparticles using ultrasound is an attractive strategy for the remote manipulation of colloidal matter using biocompatible energy inputs. However, the physical mechanisms underlying acoustic propulsion are poorly understood, and our ability to transduce acoustic energy into different types of particle motions remains limited. Here, we show that the three-dimensional shape of a colloidal particle can be rationally engineered to direct desired particle motions powered by ultrasound...
March 16, 2018: ACS Nano
Lesley W Chan, Daniel E Morse, Michael J Gordon
Near- and sub-wavelength photonic structures are used by numerous organisms (e.g., insects, cephalopods, fish, birds) to create vivid and often dynamically-tunable colors, as well as create, manipulate, or capture light for vision, communication, crypsis, photosynthesis, and defense. This review introduces the physics of moth eye (ME)-like, biomimetic nanostructures and discusses their application to reduce optical losses and improve efficiency of various optoelectronic devices, including photodetectors, photovoltaics, imagers, and light emitting diodes...
March 16, 2018: Bioinspiration & Biomimetics
F Giorgiutti-Dauphiné, L Pauchard
The drying of complex fluids involves a large number of microscopic phenomena (transport and organization of non-volatile solutes) as well as hydrodynamic and mechanical instabilities. These phenomena can be captured in drying sessile drops where different domains can be identified: strong concentration gradients, formation of a glassy or porous envelope that withstands mechanical stress, and consolidation of a layer strongly adhering to the substrate at the drop edge. In colloidal systems, we quantify the evolution of the particle volume fraction at a nanometric scale and microscopic scale and identify the conditions for the envelope formation at the free surface by balancing the effect of diffusion and evaporation...
March 19, 2018: European Physical Journal. E, Soft Matter
Brooke W Longbottom, Stefan A F Bon
Microspheres with catalytic caps have become a popular model system for studying self-propelled colloids. Existing experimental studies involve predominantly "smooth" particle surfaces. In this study we determine the effect of irregular surface deformations on the propulsive mechanism with a particular focus on speed. The particle surfaces of polymer microspheres were deformed prior to depositing a layer of platinum which resulted in the formation of nanoscopic pillars of catalyst. Self-propulsion was induced upon exposure of the micromotors to hydrogen peroxide, whilst they were dispersed in water...
March 15, 2018: Scientific Reports
E Lázaro-Lázaro, J A Moreno-Razo, M Medina-Noyola
Upon compression, the equilibrium hard-sphere liquid [pair potential uHS (r)] freezes at a packing fraction ϕf = 0.494 or, if crystallization is prevented, becomes metastable up to its glass transition at ϕg ≈ 0.58. Throughout the fluid regime (ϕ < ϕg ), we are, thus, certain that this model liquid does not exhibit any form of kinetic arrest. If, however, a small portion of these spheres (packing fraction ϕ2 ≪ ϕ) happen to ignore each other [u22 (r) = 0] but do not ignore the remaining "normal" hard spheres [u12 (r) = u21 (r) = u11 (r) = uHS (r)], whose packing fraction is thus ϕ1 = ϕ - ϕ2 , they run the risk of becoming dynamically arrested before they demix from the "normal" particles...
March 14, 2018: Journal of Chemical Physics
Daniel Stopper, Alice L Thorneywork, Roel P A Dullens, Roland Roth
Using dynamical density functional theory (DDFT), we theoretically study Brownian self-diffusion and structural relaxation of hard disks and compare to experimental results on quasi two-dimensional colloidal hard spheres. To this end, we calculate the self-van Hove correlation function and distinct van Hove correlation function by extending a recently proposed DDFT-approach for three-dimensional systems to two dimensions. We find that the theoretical results for both self-part and distinct part of the van Hove function are in very good quantitative agreement with the experiments up to relatively high fluid packing fractions of roughly 0...
March 14, 2018: Journal of Chemical Physics
Mandy Hei Man Leung, Amy Q Shen
The ability to control particle size and size distribution of nanoparticles for drug delivery is essential because it impacts on the biodistribution and cellular uptake of nanoparticles. We present a novel microfluidic assisted nanoprecipitation strategy that enables synthesis of surfactant-free curcumin encapsulated poly(lactide-co-glycolide) nanoparticles (Cur-PLGA NP) with adjustable particle diameters (30-70nm) and narrow particle size distribution (polydispersity index less than 0.2). Our Cur-PLGA NP exhibit excellent colloidal stability and inhibit degradation of curcumin...
March 15, 2018: Langmuir: the ACS Journal of Surfaces and Colloids
Niusha Lasemi, Oscar Bomati Miguel, Ruth Lahoz, Vassili Lennikov, Ulrich Pacher, Christian Rentenberger, Wolfgang Kautek
Homogeneous polycrystalline FexOy nanoparticles were generated by ablation of iron targets in water by nanosecond laser pulses at 532 nm. In ethanol, crystalline core-shell Fe/FexOy structures with size medians around 20 nm were produced. The ablation of FeWxOy targets in water resulted in crystalline hollow shells and homogeneous FeWxOy nanoparticles. In contrast, amorphous core-shell FeWxOy nanoparticles with a median size of 17 nm were produced in ethanol. The size distribution of both the FexOy and the FeWxOy particles showed a slight dependence on fluence and pulse number...
March 15, 2018: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
J Ruiz-Franco, J Marakis, N Gnan, J Kohlbrecher, M Gauthier, M P Lettinga, D Vlassopoulos, E Zaccarelli
Ultrasoft colloids typically do not spontaneously crystallize, but rather vitrify, at high concentrations. Combining in situ rheo-small-angle-neutron-scattering experiments and numerical simulations we show that shear facilitates crystallization of colloidal star polymers in the vicinity of their glass transition. With increasing shear rate well beyond rheological yielding, a transition is found from an initial bcc-dominated structure to an fcc-dominated one. This crystal-to-crystal transition is not accompanied by intermediate melting but occurs via a sudden reorganization of the crystal structure...
February 16, 2018: Physical Review Letters
Lei Pan, Hongbo Xu, Ruizhen Lv, Jun Qiu, Jiupeng Zhao, Yao Li
The laser damage behavior of three-dimensional photonic crystals (3D-PCs) with an opal structure is investigated using both experimental and simulation methods. Polystyrene (PS) colloidal crystals films with a reflection peak at 1064 nm are used as the model material. Disordered films (DF) are fabricated with PS microspheres as contrast samples. The laser-induced damage threshold (LIDT) of 3D-PCs is tested, which is as 2.35 times high as the LIDT of DF. All laser damages are derived from defects in 3D-PCs, implying that the LIDT of ideal 3D-PCs will be significantly increased...
March 14, 2018: Scientific Reports
Enrico Della Gaspera, Enrico Menin, Gianluigi Maggioni, Cinzia Sada, Alessandro Martucci
Sub-monolayers of monodisperse Au colloids with different surface coverage have been embedded in between two different metal oxide thin films, combining sol-gel depositions and proper substrates functionalization processes. The synthetized films were TiO₂, ZnO, and NiO. X-ray diffraction shows the crystallinity of all the oxides and verifies the nominal surface coverage of Au colloids. The surface plasmon resonance (SPR) of the metal nanoparticles is affected by both bottom and top oxides: in fact, the SPR peak of Au that is sandwiched between two different oxides is centered between the SPR frequencies of Au sub-monolayers covered with only one oxide, suggesting that Au colloids effectively lay in between the two oxide layers...
March 14, 2018: Materials
Jonas V Schaefer, Erik Sedlák, Florian Kast, Michal Nemergut, Andreas Plückthun
Biophysical properties of antibody-based biopharmaceuticals are a critical part of their release criteria. In this context, finding the appropriate formulation is equally important as optimizing their intrinsic biophysical properties through protein engineering, and both are mutually dependent. Most previous studies have empirically tested the impact of additives on measures of colloidal stability, while mechanistic aspects have usually been limited to only the thermodynamic stability of the protein. Here we emphasize the kinetic impact of additives on the irreversible denaturation steps of immunoglobulins G (IgG) and their antigen-binding fragments (Fabs), as these are the key committed steps preceding aggregation, and thus especially informative in elucidating the molecular parameters of activity loss...
March 14, 2018: MAbs
Maria B Vazquez-Santos, Pedro Tartaj, Enrique Morales, Jose Manuel Amarilla
Here we summarize some results on the use of TiO2 nanostructures as anode materials for more efficient Li-ion (LIBs) and Na-ion (NIBs) batteries. LIBs are the leader to power portable electronic devices, and represent in the short-term the most adequate technology to power electrical vehicles, while NIBs hold promise for large storage of energy generated from renewable sources. Specifically, TiO2 an abundant, low cost, chemically stable and environmentally safe oxide represents in LIBs an alternative to graphite for applications in which safety is mandatory...
March 14, 2018: Chemical Record: An Official Publication of the Chemical Society of Japan ... [et Al.]
Shuang Yang, Feng Zhang, Jia Tai, Yang Li, Yang Yang, Hui Wang, Jianxu Zhang, Zhigang Xie, Bin Xu, Haizheng Zhong, Kun Liu, Bai Yang
Perovskite quantum dots (PQDs) exhibit remarkable photoluminescence properties; however, their use in biological applications is hindered by their extreme sensitivity to water. We report a facile and general strategy for the preparation of aqueous colloidally stable polystyrene-b-poly(ethyl oxide) (PS-b-PEO) grafted MAPbBr3 QDs (MA = methylammonium): transferring the as-synthesized PQD@PS-b-PEO from toluene into water using precipitation in hexane as a critical intermediate step. When rehydrating the precipitate in water, the PQDs can be dispersed well individually or self-assembled into well-defined vesicular nanostructures with high photoluminescence quantum yields of up to 43%, high color purity (full width at half maximum down to 18 nm), and long average photoluminescence lifetimes up to 164 ns...
March 14, 2018: Nanoscale
Inga Markeviciute, Wolfgang Frenzel
Sample preparation is a key issue in the analysis of many real samples using ion chromatography (IC). One of the many means of sample preparation that has received considerable attention in recent years is the stopped-flow in-line dialysis approach hyphenated to IC. Using appropriate dialysis membranes undesirable high-molecular weight compounds, colloids and dispersed particulate matter are retained whereas the analyte ions pass through the membrane and are separated and quantified by IC. However, in the many papers about analytical use of in-line dialysis (not only in connection with IC) the retention of undesirable compounds has never been quantified...
August 3, 2018: Analytica Chimica Acta
Martin Wiemann, Ursula G Sauer, Antje Vennemann, Sandra Bäcker, Johannes-Georg Keller, Lan Ma-Hock, Wendel Wohlleben, Robert Landsiedel
In vitro prediction of inflammatory lung effects of well-dispersed nanomaterials is challenging. Here, the in vitro effects of four colloidal amorphous SiO₂ nanomaterials that differed only by their primary particle size (9, 15, 30, and 55 nm) were analyzed using the rat NR8383 alveolar macrophage (AM) assay. Data were compared to effects of single doses of 15 nm and 55 nm SiO₂ intratracheally instilled in rat lungs. In vitro, all four elicited the release of concentration-dependent lactate dehydrogenase, β-glucuronidase, and tumor necrosis factor alpha, and the two smaller materials also released H₂O₂...
March 13, 2018: Nanomaterials
Hélène Guénet, Edwige Demangeat, Mélanie Davranche, Delphine Vantelon, Anne-Catherine Pierson-Wickmann, Emilie Jardé, Martine Bouhnik-Le Coz, Elaheh Lotfi, Aline Dia, Jacques Jestin
The evolution of rare earth element (REE) speciation between reducing and oxidizing conditions in a riparian wetland soil was studied relative to the size fractionation of the solution. In all size fractions obtained from the reduced and oxidized soil solutions, the following analyses were carried out: organic matter (OM) characterization, transmission electron microscopy (TEM) observations as well as major and trace element analyses. Significant REE redistribution and speciation evolution between the various size fractions were observed...
March 10, 2018: Science of the Total Environment
A R Harikrishnan, Purbarun Dhar, Sateesh Gedupudi, Sarit Kumar Das
We propose a comprehensive analysis and a quasi-analytical mathematical formalism to predict the surface tension and contact angles of complex surfactant infused nanocolloids. The model rests on the foundations of the interaction potentials for the interfacial adsorption-desorption dynamics in complex multi-component colloids. Surfactant infused nanoparticle laden interface problems are difficult to deal with due to the many-body interactions and interfaces involved at the meso-nanoscales. The model is based upon the governing role of thermodynamic and chemical equilibrium parameters in modulating the interfacial energies...
March 13, 2018: Journal of Physical Chemistry. B
Hui Lu, Li Zhu, Chuanlong Zhang, Kexiang Chen, Yiping Cui
To solve the problem that analyte molecules are not easy to enter "hot spots" on a conventional solid SERS substrate, we developed a mixing assisted "hot spots" occupying (MAHSO) SERS strategy to improve utilization of "hot spots". Comparing with the conventional substrate, MAHSO substrate enhances the sensitivity of SERS measurement by thousands of times. The MAHSO substrate possesses excellent properties of high enhancement, high uniformity and long-term stability because MAHSO substrate is integrated inside an ultrafast microfluidic mixer...
March 13, 2018: Analytical Chemistry
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