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Langmuir: the ACS Journal of Surfaces and Colloids

Piyush Jain, Olivier Vincent, Abraham Duncan Stroock
Probing nano-confined solutions in tortuous, mesoporous media is challenging due to pore size, complex pore connectivity, and coexistence of multiple components and phases. Here, we use optical reflectance to experimentally investigate the wetting and drying of a mesoporous medium with ~3 nm diameter pores containing aqueous solutions of sodium chloride and lithium chloride. We show that the vapor activities, i.e., relative humidities, that correspond to optical features in the isotherms for solutions can be used to deduce the thermodynamic state of a nanoscopic solution that undergoes evaporation and crystallization upon drying, and condensation and deliquescence when increasing the relative humidity...
February 20, 2019: Langmuir: the ACS Journal of Surfaces and Colloids
Tulio Honorio
The interactions of calcium silicate hydrates with water are at the heart of critical features of cement-based materials behavior such as drying and autogenous shrinkage, hysteresis, creep and thermal expansion. In this article, the interactions between nanocrystalline layers of calcium silicate hydrates are computed from Grand Canonical Monte Carlo (GCMC) molecular simulations. The effects of temperature, chemical potential and pressure on these interactions are studied. The results are confronted with simulation and experimental data found in the literature concerning surface energy, cohesive pressure and out-of-plane elastic properties...
February 20, 2019: Langmuir: the ACS Journal of Surfaces and Colloids
You Zhou, Boris Albijanic, Bogale Tadesse, Yuling Wang, Jianguo Yang, Xiang-Nan Zhu
Bubble-particle attachment is the key step for successful flotation. Modelling of attachment interactions between air bubbles and particles after their collision can be analysed using the Stefan-Reynolds model (immobile bubble surfaces) and the modified Stefan-Reynolds model (mobile bubble surfaces). However, these models have been rarely used, and the limitations of these models have not yet been reported. The objective of this paper is to address this matter under a wide range of experimental flotation conditions...
February 20, 2019: Langmuir: the ACS Journal of Surfaces and Colloids
Peipei Wang, Jan J Cilliers, Stephen Johan Neethling, Pablo R Brito-Parada
The rising behavior of bubbles, initially half and fully coated with glass beads of various sizes, was investigated. The bubble velocity, aspect ratio and oscillation periods were determined using high-speed photography and image analysis. In addition, the acting forces, drag modification factor and modified drag coefficient were calculated and interpreted. Results show that the aspect ratio oscillation of the rising bubbles is similar, irrespective of the attached particle size. As the particle size is increased, the rising bubbles have a lower velocity and aspect ratio amplitude, with the time from release to each aspect ratio peak increasing...
February 20, 2019: Langmuir: the ACS Journal of Surfaces and Colloids
Pina Atalanta Fritz, Stefanie C Lange, Marcel Giesbers, Han Zuilhof, Remko M Boom, Karin Schroen
During electrophoretic deposition of graphene oxide (GO) sheets on silicon substrates, not only deposition but also simultaneous anodic oxidation of the silicon substrate takes place, leading to a three-layered material. SEM images reveal the presence of GO sheets on the silicon substrate, and this is also confirmed by XPS, albeit that the carbon portion increases with increasing emission angle, hinting at a thin carbon layer. With increasing applied potential and increasing conductivity of the GO solution the carbon signal decreases, while the overall thickness of the added layer formed on top of the silicon substrate increases...
February 20, 2019: Langmuir: the ACS Journal of Surfaces and Colloids
Muhammad Rizwanur Rahman, Prashant R Waghmare
In this study, we present experimental and theoretical analyses of evaporating double emulsion drop resting on a substrate. Multistage evaporation of outer and inner droplet is witnessed. The complete evaporation of outer drop and the initialization of the inner drop evaporation demonstrate an interesting transition dynamics. After the apparent completion of evaporation of the inner phase of a double emulsion drop, surprisingly, formation of a daughter droplet is observed. We further investigated to hypothesize this phenomenon and achieved the formation of the daughter droplet for a single phase drop as well...
February 19, 2019: Langmuir: the ACS Journal of Surfaces and Colloids
Dongxiang Xue, Jingjing Wang, Xiyong Song, Wei Wang, Lintao Ye, Yang Liu, Qingtong Zhou, Zhong-Xing Jiang, Zhijie Liu, Houchao Tao
Membrane mimics are indispensable tools in the structural and functional understanding of membrane proteins (MPs). Given stringent requirements of integral MP manipulations, amphiphile replacement is often required in sample preparation for various biophysical purposes. Current protocols generally rely on physical methodologies and rarely reach complete replacement. In comparison, we report herein a chemical alternative that facilitates the exhaustive exchange of membrane mimicking systems for MP reconstitution...
February 19, 2019: Langmuir: the ACS Journal of Surfaces and Colloids
Dowan Kim, Donghyo Hahm, Soonhyoung Kwon, Jeewoo Lim, Kookheon Char
In this paper, we report the synthesis and mesoporous film formation of hydrophobic rod-like poly( p-phenyleneethynylene)s (PPEs) and present porosity-dependent quenching studies using 1,3,5-trinitrotoluene (TNT) vapors. Non-solvent vapor-induced phase separation (NVIPS) was used to induce pore formation during film casting, and the concentration of PPEs in the casting solution was controlled carefully to prevent excimer formation. We found that the structure of the sidechains of the PPEs strongly influence the range of the relative humidity at which controlled pore generation occurs, which could be rationalized from interfacial energies calculated from contact angle measurements...
February 19, 2019: Langmuir: the ACS Journal of Surfaces and Colloids
Shogo Himori, Shoichi Nishitani, Toshiya Sakata
In this paper, we demonstrate the use of a monolayer film electrografted via diazonium chemistry for controlling the potential response of field-effect transistor (FET)-based sensor. A 4-nitrobenzenediazonium (NBD) salt is electrografted on an extended-Au-gate FET (EG-Au-FET) with or without using a radical scavenger by cyclic voltammetry (CV), resulting in the formation of a monolayer or multilayer. In particular, the surface coverage of the aryl-derivative monolayer on the Au gate electrode gradually increases with increasing number of potential cycles in CV...
February 19, 2019: Langmuir: the ACS Journal of Surfaces and Colloids
Rino Ichikawa, Satoshi Kajiyama, Misato Iimura, Takashi Kato
The orientation of the c-axis in octacalcium phosphate (OCP) nanocrystals that were incorporated into hybrid thin films were successfully tuned using poly(vinyl alcohol) (PVA) thin-film templates of varying thickness. This approach was inspired by biomineralization. Thicker PVA templates enhanced the c-axis orientation of the OCP crystals perpendicular to the substrate. Using this approach with a 900-nm-thick PVA template, OCP/PVA hybrid thin films (1.8 μm thick) with perpendicular c-axis orientation to the substrate were formed...
February 19, 2019: Langmuir: the ACS Journal of Surfaces and Colloids
Ignacio Martín-Fabiani, David Makepeace, Philip Richardson, Jennifer Lesage de la Haye, Diego Alba Venero, Sarah E Rogers, Franck D'Agosto, Muriel Lansalot, Joseph L Keddie
The distribution of hydrophilic species, such as surfactants, in latex films is of critical importance for the performance of adhesives, coatings and inks, among others. However, the evolution of this distribution during the film formation process and in the resulting dried films remains insufficiently elucidated. Here, we present in situ (wet) and ex situ (dry) SANS experiments that follow the film formation of two types of latex particles, which differ in their stabilizer: either a covalently bonded poly(methacrylic acid) (PMAA) segment or a physically adsorbed surfactant (sodium dodecyl sulfate, SDS)...
February 19, 2019: Langmuir: the ACS Journal of Surfaces and Colloids
Yazhou Huang, Lei Liu, Junjie Yang, Yunfei Chen
Solid-lubricanting films are usually applied to reduce friction and adhesion of micro/nanoelectromechanical systems (MEMS/NEMS). Due to the special structure, MoS2 is endowed with excellent lubricity. Layer-controlled ultrathin MoS2 films with strong interactions to the underlying substrates were prepared by atomic layer deposition (ALD) using MoCl5 and H2S and characterized by various measures. Nanotribological properties of the MoS2 films with different thicknesses were observed by an atomic force microscope (AFM) tip under various loads...
February 19, 2019: Langmuir: the ACS Journal of Surfaces and Colloids
Zhengchen Wu, Ting Huang, Tiesheng Li, Lei Li
Hierarchical carbon/reduced graphene oxide /FeOx (CGF) composite has been successfully prepared utilizing a sequential process of immersion and carbonization. During the immersion of melamine foam in liquid precursor, the graphene oxide covers on the interconnected framework of foam and is decorated by metallic ions simultaneously. Therefore, the hierarchical structure is constructed in one step. The CGF exhibits a maximum reflection loss of as much as -51.2 dB and an ultra-wide effective absorption bandwidth of 8...
February 19, 2019: Langmuir: the ACS Journal of Surfaces and Colloids
Soumita Maiti, Nitish Singh, Animangsu Ghatak
Reversible alteration between different emulsion morphologies like core-shell and Janus is conventionally triggered by altering the interfacial energy between different phases. In contrast, here we show that the morphology of dispersed droplets can change also when the emulsion is sufficiently confined between two parallel plates. In particular we use three immiscible phases: silicone oil, paraffin oil and aqueous solution of surface active agents like Agarose, SDS, AOT, CTAB to generate oil in water emulsion consisting of complex morphologies of the dispersed droplets...
February 18, 2019: Langmuir: the ACS Journal of Surfaces and Colloids
Miao He, Guoxia Fei, Zhuo Zheng, Zhengang Cheng, Zhanhua Wang, Hesheng Xia
Platinum-decorated graphene aerogel microspheres were fabricated through a combined electrospraying, freeze-casting and solvothermal process. Platinum nanoparticles with a narrow size distribution are evenly anchored on the graphene aerogel microspheres without agglomeration benefitting from the distinct center-diverging microchannel structure of the graphene aerogel microspheres, which results in the as-prepared catalysts presenting excellent electrocatalytic performance including high electrocatalytic activity and high poison tolerance towards methanol electrooxidation, showing great potential for direct methanol fuel cell anode catalysts...
February 18, 2019: Langmuir: the ACS Journal of Surfaces and Colloids
Jie Liu, Kun Huang, Wenqian Liu, Huizhou Liu
Extraction and recovery of low-concentration valuable metals from various complex aqueous solutions or industrial waste waters have attract extensive interests in recent years. In our previous works, we suggested a novel technique called bubbling organic liquid membrane extraction by spreading and covering an organic extractant with extremely small volume on the surface of gas bubbles to form a layer of gas bubble-supported organic liquid membrane for selective extraction and enrichment of low-concentration targets from dilute aqueous solutions...
February 18, 2019: Langmuir: the ACS Journal of Surfaces and Colloids
Dong In Yu, Ho Jae Kwak, Chulmin Park, Chiwoong Choi, Narayan Pangdurang Sapkal, Jiwoo Hong, Moo Hwan Kim
In this study, existing knowledge on the wetting criterion, i.e., the intrinsic contact angle, for distinguishing between hydrophilic and hydrophobic textured surfaces is verified experimentally. A precise apparent contact angle is measured on micro-, nano- and micro/nano-textured surfaces to quantitatively define the surface wetting conditions. In particular, X-ray tomography is introduced to measure precise geometric morphologies of nano- and micro/nano-textured surfaces, and the wetting state of the textured surfaces is clearly visualized using synchrotron X-ray imaging...
February 18, 2019: Langmuir: the ACS Journal of Surfaces and Colloids
Deniz Yaşar Öztaş, Mine Altunbek, Deniz Uzunoğlu, Hülya Yılmaz, Demet Çetin, Zekiye Suludere, Mustafa Culha
Surface-enhanced Raman scattering (SERS) based-single cell analysis is an emerging approach to obtain molecular level information from molecular dynamics in a living cell. In this study, endosomal biochemical dynamics was investigated based on size and surface chemistry dependent uptake of gold nanoparticles (AuNPs) on single cells over time using SERS. MDA-MB-231 breast cancer cells were exposed to 13 nm and 50 nm AuNPs and their poly-Adenine oligonucleotide modified forms by controlling the order and combination of AuNPs...
February 18, 2019: Langmuir: the ACS Journal of Surfaces and Colloids
Jimin Park, Hyunseon Seo, Hae Won Hwang, Jonghoon Choi, Kyeongsoo Kim, Goeen Jeong, Eun Shil Kim, Hyung-Seop Han, Yeon-Wook Jung, Youngmin Seo, Hojeong Jeon, Hyun-Kwang Seok, Yu-Chan Kim, Myoung-Ryul Ok
Despite significant advances in the design of metallic materials for bare metal stents (BMSs), restenosis induced by the accumulation of smooth muscle cells (SMCs) has been a major constraint on improving the clinical efficacy of stent implantation. Here, a new strategy for avoiding this issue utilizing hydrogen peroxide (H2O2) generated by the galvanic coupling of nitinol (NiTi) stents and biodegradable magnesium-zinc (Mg-Zn) alloys is reported. The amount of H2O2 released is carefully optimized via the biodegradability engineering of the alloys and by controlling the immersion time to selectively inhibit the proliferation and function of SMCs without harming vascular endothelial cells (VECs)...
February 18, 2019: Langmuir: the ACS Journal of Surfaces and Colloids
Changmin Shao, Yuxiao Liu, Junjie Chi, Zhuoyue Chen, Jie Wang, Yuanjin Zhao
Three-dimensional (3D) cell spheroids have a demonstrated value for in vitro biological research and therapeutics development. Attempts to this technique focus on the developing of effective methods for fabricating cell spheroids. Here, inspired by the heterogeneously textured wettability bumps (with hydrophilic peaks and hydrophobic bases) of Stenocara beetle, we present a bio-templated substrate with wettable hydrogel arrays for culturing the cell spheroids. The bio-templates were Morpho butterfly wings with chitin and protein components, which could provide a natural superhydrophobic surface without any modification...
February 18, 2019: Langmuir: the ACS Journal of Surfaces and Colloids
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