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Rad Sadri, Maryam Hosseini, S N Kazi, Samira Bagheri, Ali H Abdelrazek, Goodarz Ahmadi, Nashrul Zubir, Roslina Ahmad, N I Z Abidin
In this study, we synthesized covalently functionalized graphene nanoplatelet (GNP) aqueous suspensions that are highly stable and environmentally friendly for use as coolants in heat transfer systems. We evaluated the heat transfer and hydrodynamic properties of these nano-coolants flowing through a horizontal stainless steel tube subjected to a uniform heat flux at its outer surface. The GNPs functionalized with clove buds using the one-pot technique. We characterized the clove-treated GNPs (CGNPs) using X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM)...
July 17, 2017: Journal of Colloid and Interface Science
Oliver Plümper, Alexandru Botan, Catharina Los, Yang Liu, Anders Malthe-Sørenssen, Bjørn Jamtveit
The transport of fluids through the Earth's crust controls the redistribution of elements to form mineral and hydrocarbon deposits, the release and sequestration of greenhouse gases, and facilitates metamorphic reactions that influence lithospheric rheology. In permeable systems with a well-connected porosity, fluid transport is largely driven by fluid pressure gradients. In less permeable rocks, deformation may induce permeability by creating interconnected heterogeneities, but without these perturbations, mass transport is limited along grain boundaries or relies on transformation processes that self-generate transient fluid pathways...
September 2017: Nature Geoscience
Yanyu Shen, Guijin He, Yongsheng Guo, Hujun Xie, Wenjun Fang
Hyperbranched polyglycerol (HPG) is modified with dodecanethiol (DS) via the "thiol-ene" click reaction to obtain an amphiphilic product DSHPG. The molecular structures of DSHPG samples are characterized by NMR, FTIR, and GPC, and the thermal behaviors are characterized by DSC and TGA. Gold nanoparticles (Au NPs) are prepared with DSHPG as the stabilizer and surface-modification reagent. The size of Au NPs can be tuned by changing the molecular weight of HPG. It is observed that the HPG molecular weights of 1123, 3826, and 55,075 lead to the NP diameters of 4...
September 6, 2017: Nanoscale Research Letters
Daniel Andrén, Lei Shao, Nils Odebo Länk, Srdjan S Aćimović, Peter Johansson, Mikael Käll
Plasmonic gold nanorods are prime candidates for a variety of biomedical, spectroscopy, data storage, and sensing applications. It was recently shown that gold nanorods optically trapped by a focused circularly polarized laser beam can function as extremely efficient nanoscopic rotary motors. The system holds promise for applications ranging from nanofluidic flow control and nanorobotics to biomolecular actuation and analysis. However, to fully exploit this potential, one needs to be able to control and understand heating effects associated with laser trapping...
September 20, 2017: ACS Nano
Lihong Lao, Liling Fu, Genggeng Qi, Emmanuel P Giannelis, Jintu Fan
We demonstrate in this study, a wrinkle-free, superhydrophilic cotton fabric (contact angle ~ 0o) by uniformly attaching specially engineered nanoparticles to plasma pre-treated cotton fabric. Because of their highly charged nature, the nanoparticles are firmly anchored on the fabric via electrostatic interactions, as confirmed by microscopy and chemical analyses. The durability of wetting behavior and wrinkle-free property of the nanoparticle-coated fabrics was evaluated via aging, laundering and abrasion tests...
September 5, 2017: ACS Applied Materials & Interfaces
Liang Dai, Jeremy J Jones, Alexander R Klotz, Stephen Levy, Patrick S Doyle
Manipulating and measuring single-molecule dynamics and reactions in nanofluidics is a rapidly growing field with broad applications in developing new biotechnologies, understanding nanoconfinement effects in vivo, and exploring new phenomena in confinement. In this work, we investigate the kinetics of DNA collapse in nanoslits using single T4-DNA (165.6 kbp) and λ-DNA (48.5 kbp), with particular focus on the measurement of the nucleation and annealing times. Fixing the ethanol concentration at 35% and varying the slit height from 2000 to 31 nm, the nucleation time dramatically decreases from more than 1 hour to a few minutes or less...
September 4, 2017: Soft Matter
Cong Qi, Chunyang Li, Guiqing Wang
The flow and heat transfer characteristics of TiO2-water nanofluids with different nanoparticle mass fractions in a spirally fluted tube and a smooth tube are experimentally investigated at different Reynolds numbers. The effects of pH values and doses of dispersant agent on the stability of TiO2-water nanofluids are discussed. The effects of nanoparticle mass fractions and Reynolds numbers on Nusselt numbers and frictional resistance coefficients in the spirally fluted tube and the smooth tube are also investigated...
September 2, 2017: Nanoscale Research Letters
Hao Zhu, Haitao Li, Joseph Robertson, Arvind Balijepalli, Sergiy Krylyuk, Albert Davydov, John J Kasianowicz, John Suehle, Qiliang Li
Novel nanofluidic chemical cells based on self-assembled solid-state SiO2 nanotubes on silicon-on-insulator (SOI) substrate have been successfully fabricated and characterized. The vertical SiO2 nanotubes with a smooth cavity are built from Si nanowires which were epitaxially grown on the SOI substrate. The nanotubes have rigid, dry-oxidized SiO2 walls with precisely controlled nanotube inner diameter, very attractive for chemical-/bio-sensing applications. No dispersion/aligning procedures were involved in the nanotube fabrication and integration by using this technology, enabling clean and smooth chemical cell...
August 30, 2017: Nanotechnology
Sarmad Al-Anssari, Muhammad Arif, Shaobin Wang, Ahmed Barifcani, Stefan Iglauer
Nanofluids (i.e. nanoparticles dispersed in a fluid) have tremendous potential in a broad range of applications, including pharmacy, medicine, water treatment, soil decontamination, or oil recovery and CO2 geo-sequestration. In these applications nanofluid stability plays a key role, and typically robust stability is required. However, the fluids in these applications are saline, and no stability data is available for such salt-containing fluids. We thus measured and quantified nanofluid stability for a wide range of nanofluid formulations, as a function of salinity, nanoparticle content and various additives, and we investigated how this stability can be improved...
August 18, 2017: Journal of Colloid and Interface Science
Peng Zhai, Yuechen Wang, Chang Liu, Xun Wang, Shien-Ping Feng
This study demonstrates that the application of an external electrical potential to a phenyl-sulfonic functionalized graphene (SG)/water suspension distinctly enhances its electrical conductivity via the structural transition from isolated clusters to a 3D SG network. Microstructural and alternating current impedance spectroscopy studies indicate that the surface charge plays an important role in the state of dispersion and connectivity of the SG in the suspension due to the potential-dependent interactions with functional groups on the SG surface in the presence of an external electrical potential...
August 21, 2017: Small
Yea Ram Lee, Daehwan Park, Sang Koo Choi, Miju Kim, Heung Soo Baek, Jin Nam, Chan Bok Chung, Chinedum O Osuji, Jin Woong Kim
Cellulose fibrils, unique plant-derived semicrystalline nanomaterials with exceptional mechanical properties, have significant potential for rheology modification of complex fluids due to their ability to form a physically associated semiflexible fibrillary network. Here, we report new associative cellulose nanocrystals (ACNCs) with stress-responsive rheological behaviors in an aqueous solution. The surface-mediated living radical polymerization was employed to graft poly(stearyl methacrylate-co-2-methacryloxyethyl phosphorylcholine) brushes onto the nanofibrils, and then 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO)-mediated oxidation was conducted to produce nanoscale ACNCs in the aqueous solution...
September 13, 2017: ACS Applied Materials & Interfaces
Tasawar Hayat, Mumtaz Khan, Muhammad Ijaz Khan, Ahmed Alsaedi, Muhammad Ayub
This article predicts the electromagneto squeezing rotational flow of carbon-water nanofluid between two stretchable Riga plates. Riga plate is known as electromagnetic actuator which is the combination of permanent magnets and a span wise aligned array of alternating electrodes mounted on a plane surface. Mathematical model is developed for the flow problem with the phenomena of melting heat transfer, viscous dissipation and heat generation/absorption. Water and kerosene oil are utilized as the base fluids whereas single and multi-wall carbon nanotubes as the nanomaterials...
2017: PloS One
Sudip Chakraborty, Hemant Kumar, Chandan Dasgupta, Prabal K Maiti
Understanding the properties of strongly confined water is important for a variety of applications such as fast flow and desalination devices, voltage generation, flow sensing, and nanofluidics. Confined water also plays an important role in many biological processes such as flow through ion channels. Water in the bulk exhibits many unusual properties that arise primarily from the presence of a network of hydrogen bonds. Strong confinement in structures such as carbon nanotubes (CNTs) substantially modifies the structural, thermodynamic, and dynamic (both translational and orientational) properties of water by changing the structure of the hydrogen bond network...
August 15, 2017: Accounts of Chemical Research
Jiaye Su, Yunzhen Zhao, Chang Fang, Syed Bilal Ahmed, Yue Shi
Nanoparticles are highly versatile and exhibit broad applications in tuning material properties. Herein, we show through molecular dynamics simulations the possibility of a nanometer water pump, driven by the motion of nanoparticles (NPs) on a membrane surface. Surprisingly, considerable net water flux can be induced through a carbon nanotube (CNT) that is perpendicular to the NP motion. The water transport can occur in a highly controllable fashion, not only by using a single NP with different forces, but also by varying the CNT length or the NP number...
August 23, 2017: Physical Chemistry Chemical Physics: PCCP
Dongju Lee, Jin-Ju Park, Min-Ku Lee, Gyoung-Ja Lee
Developing a thermally stable nanofluid that can maintain good thermo-conductive and flow performance at moderate or elevated temperatures for prolonged periods of time is a great challenge in heat transfer applications. Here, the thermal conductivity and rheological properties as well as their thermal stability characteristics of a nanofluid containing two-dimensional (2D) hexagonal boron nitride nanosheets (h-BNNSs) in ethylene glycol (EG) are presented, in comparison with those for a graphene oxide (GO) nanofluid as a counterpart...
August 14, 2017: Nanotechnology
Junho Hwang, Tatsuki Sekimoto, Wei-Lun Hsu, Sho Kataoka, Akira Endo, Hirofumi Daiguji
The thermal dependence of salinity-gradient-driven energy conversion by reverse electrodialysis using a mesoporous silica thin film with pores ca. 2-3 nm in diameter was studied in a temperature range of 293-333 K. As the temperature increases, the surface charge density of mesopores increases owing to an increase in the zeta potential of the pore walls, which in turn increases the concentration of counter-ions in the electrical double layer. The ion mobility also increases with increasing temperature owing to a decrease in the liquid viscosity...
August 24, 2017: Nanoscale
Mubarak Ali, Ishtiaq Ahmed, Patricio Ramirez, Saima Nasir, Javier Cervera, Salvador Mafe, Christof M Niemeyer, Wolfgang Ensinger
We demonstrate experimentally and theoretically a nanofluidic device for the selective recognition of the cesium ion by exploiting host-guest interactions inside confined geometry. For this purpose, a host molecule, i.e., the amine-terminated p-tert-butylcalix[4]arene-crown (t-BuC[4]C-NH2), is successfully synthesized and functionalized on the surface of a single conical nanopore fabricated in a poly(ethylene terephthalate) (PET) membrane through carbodiimide coupling chemistry. On exposure to the cesium cation, the t-BuC[4]C-Cs(+) complex is formed through host-guest interaction, leading to the generation of positive fixed charges on the pore surface...
August 24, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
Yaping Feng, Weiwei Zhu, Wei Guo, Lei Jiang
Well-developed structure-function relationships in living systems have become inspirations for the design and application of innovative materials. Building artificial nanofluidic systems for energy conversion undergoes three essential steps of structural and functional development with the uptake of separate biological inspirations. This research field started from the mimicking of the bioelectric function of electric eels, wherein a transmembrane ion concentration gradient is converted into ultrastrong electrical impulses via membrane-protein-regulated ion transport...
August 10, 2017: Advanced Materials
Jia-Wei Yeh, Kylan Szeto
Stretching single chromosomal DNA fibers in nanofluidic devices has become a valuable tool for studying the genome and more recently the epigenome. Although nanofluidic technology has been extensively used in single molecular DNA analysis, compared to bare DNA, much less work has been done to elongate chromatin, and only a few studies utilize more biologically relevant samples such as native eukaryotic chromatin. Here, we provide a method for stretching and imaging individual chromatin fibers within a micro- and nanofluidic device...
July 2017: Biomicrofluidics
Vida Jamali, Evan G Biggers, Paul van der Schoot, Matteo Pasquali
Line tension, i.e., the force on a three-phase contact line, has been a subject of extensive research due to its impact on technological applications including nanolithography and nanofluidics. However, there is no consensus on the sign and magnitude of the line tension, mainly because it only affects the shape of small droplets, below the length scale dictated by the ratio of line tension to surface tension σ/τ. This ratio is related to the size of constitutive molecules in the system, which translates to a nanometer for conventional fluids...
August 23, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
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