Impact of −C₂H₅ and −OH Functionalizations on the Water Flow Blockage in Carbon Nanotubes

Carbon nanotube (CNT) filter membranes are excellent promising materials for efficient desalination. In our previous studies (<i>Phys. Rev. Lett.</i> <b>2015,</b> <i>115</i>, 164502) we showed that Na⁺ cations in seawater would easily bind at the entrance of the pristine CNT due to cation−π interaction, resulting in the blocking of water flow through the nanotube. Here, we systematically investigate the binding behavior of ions and blockage effects of water flow in much more chemically realistic CNTs that are functionalized at the ends with various density of hydrophilic −OH or hydrophobic −C₂H₅ groups. Our findings show that hydrophobic −C₂H₅ groups will weaken the cation−π interaction between Na⁺ ions and CNTs, and accordingly, water flows through the CNTs fluently. CNTs functionalized with −C₂H₅ groups in moderate density are expected to work excellently in desalination application, whereas functionalization with hydrophilic −OH groups cannot prevent the blockage of water. This finding brings insights in designing efficient desalination filter materials based on CNT

Schematic of the experimental set-up.

<p>PC: personal computer; Filter: 355 nm long-pass filter; ICCD: intensified charge-coupled device; THG: third harmonic generator output at 355 nm.</p

Motor Oil Classification Based on Time-Resolved Fluorescence

<div><p>A time-resolved fluorescence (TRF) technique is presented for classifying motor oils. The system is constructed with a third harmonic Nd:YAG laser, a spectrometer, and an intensified charge coupled device (ICCD) camera. Steady-state and time-resolved fluorescence (TRF) measurements are reported for several motor oils. It is found that steady-state fluorescence is insufficient to distinguish the motor oil samples. Then contour diagrams of TRF intensities (CDTRFIs) are acquired to serve as unique fingerprints to identify motor oils by using the distinct TRF of motor oils. CDTRFIs are preferable to steady-state fluorescence spectra for classifying different motor oils, making CDTRFIs a particularly choice for the development of fluorescence-based methods for the discrimination and characterization of motor oils. The two-dimensional fluorescence contour diagrams contain more information, not only the changing shapes of the LIF spectra but also the relative intensity. The results indicate that motor oils can be differentiated based on the new proposed method, which provides reliable methods for analyzing and classifying motor oils.</p></div

LIF spectra at specific time gates (including 5 ns, 20 ns, 35 ns, 50 ns, 65 ns, 75 ns).

<p>(a) Mobil 0W-40, (b) Mobil 5W-30, (c) Mobil 5W-40, (d) Mobil 20W-40, (e) Shell 5W-40, (f) Shell 15W-40, (g) Castrol 5W-40, (h) Prestone 5W-40, and (i) GreatWall 10W-50. The normalized fluorescence intensity (y-axis) and the wavelength (x-axis) are used as axes. The wavelength range is 360 nm to 575 nm. The integration time is set to 5 ns.</p

Petrogenesis of Neoarchean granitic gneisses from the Daqishan area of the Dabie orogen and implications for the early crustal evolution of the Northern Yangtze Craton

The Yangtze Craton is one of the crucial cratons constitued the eastern Asia continent. It is characterized by Archaean to Paleoproterozoic basement rocks, making it an excellent area to study the Precambrian geologic and tectonic regime. Recently, abundant Archaean rocks have been reported from the Dabie Orogen, which providing important information to understanding the early evolution of the Northern Yangtze Craton. In this contribution, we present petrological, whole-rock geochemical, and zircon U – Pb – Hf isotopic analyses on newly discovered Neoarchean granite in the Dabie Orogen. We identified 2744 ± 10 Ma and 2715 ± 11 Ma (~2.74 Ga) Na-rich granitic gneisses, 2691 ± 6 Ma and 2696 ± 8 Ma (~2.69 Ga) A2-type granitic gneisses, and 2664 ± 8 Ma, 2664 ± 6 Ma, 2672 ± 7 Ma, 2642 ± 10 Ma (~2.66 Ga) A1-type granitic/syenite gneisses from the Daqishan area of the Dabie Orogen. Geochemical and zircon Hf isotope data indicate that the ~ 2.74 Ga Na-rich granitic gneisses were partial melting products of thickened mafic crust with limited depleted mantle input, while the 2.69 Ga and 2.66 Ga A-type granitic gneisses represent felsic magmatism in a post-collisional to an extensional tectonic setting. Based on our research, we categorized the Northern Yangtze Craton into the Kongling domain and Dabie domain by comparing with the distribution of the zircon U-Pb magmatic ages and metamorphic events. We suggest that the initial unified basement of the northern proto-Yangtze Craton formed during the Nuna supercontinent cycle at ~ 2.0 Ga.</p

Relationships between the shoot Cu concentration (A), root Cu concentration (B) and the ratio of the Cu concentration in shoots to that in roots of <i>E</i>. <i>haichowensis</i> (C) and the leaf transpiration rate.

<p>Mean value followed by different letter is statistically significant (ANOVA; Duncan multiple range test, p<0.01).</p

ABA contents in the leaves of <i>O</i>. <i>glazioviana</i> and <i>E</i>. <i>haichowensis</i> seedlings with treatment with 0 or 50 μM CuSO₄.

<p>Mean value followed by different letter is statistically significant (ANOVA; Duncan multiple range test, p<0.05).</p

Wax content in leaves and stomatal density of the leaf epidermis of <i>O</i>. <i>glazioviana</i> and <i>E</i>. <i>haichowensis</i> seedlings.

<p>Mean value followed by different letter is statistically significant (ANOVA; Duncan multiple range test, p<0.05).</p><p>Wax content in leaves and stomatal density of the leaf epidermis of <i>O</i>. <i>glazioviana</i> and <i>E</i>. <i>haichowensis</i> seedlings.</p

The lower epidermis as shown by SEM.

<p>(<b>A</b>) Lower epidermis of <i>O</i>. <i>glazioviana</i>, (<b>B</b>) magnifying epidermal stoma of <i>O</i>. <i>glazioviana</i>, (<b>C</b>) lower epidermis of <i>E</i>. <i>haichowensis</i>, and (<b>D</b>) magnifying epidermal stoma of <i>E</i>. <i>haichowensis</i>.</p

Microstructure of the root cells of two plant species.

<p>(<b>A</b>) Paraffin cross section of <i>O</i>. <i>glazioviana</i>, (<b>B</b>) electron micrograph of <i>O</i>. <i>glazioviana</i> cross-section, (<b>C</b>) paraffin cross section of <i>E</i>. <i>haichowensis</i>, and (<b>D</b>) electron micrograph of a cross section of <i>E</i>. <i>haichowensis</i>.</p