Fixing Colloidal Motions at Water/Air Interface with Micrometer Scale Resolution

Fast colloidal motions driven by surface tension gradient are created in a thin water layer. Unlike using solid boundaries to limit the colloidal flow, our work relaxes this condition by directly placing bulk fluid next to an open air environment. When the colloidal flow along the air/water interface is interfered with stationary objects, repetitive semicircular motions, that is, micro eddy, are frequently observed in domains as small as 2 μm. We assign the capillary convection between the liquid next to the air and that from the bulk as the driving force for the observed motions. Relationships among the maximum speed, temperature gradient, and thickness of the liquid layer are experimentally investigated and numerically analyzed. Our results could inspire future designs of micromechanical motors or fluidic mixing in a miniature device

Fixing Colloidal Motions at Water/Air Interface with Micrometer Scale Resolution

Fast colloidal motions driven by surface tension gradient are created in a thin water layer. Unlike using solid boundaries to limit the colloidal flow, our work relaxes this condition by directly placing bulk fluid next to an open air environment. When the colloidal flow along the air/water interface is interfered with stationary objects, repetitive semicircular motions, that is, micro eddy, are frequently observed in domains as small as 2 μm. We assign the capillary convection between the liquid next to the air and that from the bulk as the driving force for the observed motions. Relationships among the maximum speed, temperature gradient, and thickness of the liquid layer are experimentally investigated and numerically analyzed. Our results could inspire future designs of micromechanical motors or fluidic mixing in a miniature device

Fixing Colloidal Motions at Water/Air Interface with Micrometer Scale Resolution

Fast colloidal motions driven by surface tension gradient are created in a thin water layer. Unlike using solid boundaries to limit the colloidal flow, our work relaxes this condition by directly placing bulk fluid next to an open air environment. When the colloidal flow along the air/water interface is interfered with stationary objects, repetitive semicircular motions, that is, micro eddy, are frequently observed in domains as small as 2 μm. We assign the capillary convection between the liquid next to the air and that from the bulk as the driving force for the observed motions. Relationships among the maximum speed, temperature gradient, and thickness of the liquid layer are experimentally investigated and numerically analyzed. Our results could inspire future designs of micromechanical motors or fluidic mixing in a miniature device

A Bicyclo[4.2.0]octene-Derived Monomer Provides Completely Linear Alternating Copolymers via Alternating Ring-Opening Metathesis Polymerization (AROMP)

Strained bicyclic carbomethoxy olefins were utilized as substrates in alternating ring-opening metathesis polymerization and found to provide low-dispersity polymers with novel backbones. The polymerization of methyl bicyclo[4.2.0]­oct-7-ene-7-carboxylate with cyclohexene in the presence of the fast-initiating Grubbs catalyst (H₂IMes)­(3-Br-Pyr)₂Cl₂RuCHPh leads to a completely linear as well as alternating copolymer, as demonstrated by NMR spectroscopy, isotopic labeling, and gel permeation chromatography. In contrast, intramolecular chain-transfer reactions were observed with [5.2.0] and [3.2.0] bicyclic carbomethoxy olefins, although to a lesser extent than with the previously reported monocyclic cyclobutenecarboxylic ester monomers [Song, A.; Parker, K. A.; Sampson, N. S. J. Am. Chem. Soc. 2009, 131, 3444]. Inclusion of cyclohexyl rings fused to the copolymer backbone minimizes intramolecular chain-transfer reactions and provides a framework for creating alternating functionality in a one-step polymerization

Color and Texture Morphing with Colloids on Multilayered Surfaces

Dynamic morphing of marine species to match with environment changes in color and texture is an advanced means for surviving, self-defense, and reproduction. Here we use colloids that are placed inside a multilayered structure to demonstrate color and texture morphing. The multilayer is composed of a thermal insulating base layer, a light absorbing mid layer, and a liquid top layer. When external light of moderate intensity (∼0.2 W cm^–2) strikes the structure, colloids inside the liquid layer will be assembled to locations with an optimal absorption. When this system is exposed to continuous laser pulses, more than 18 000 times of reversible responses are recorded, where the system requests 20 ms to start the response and another 160 ms to complete. The flexibility of our concept further allows the system to be built on a variety of light-absorbing substrates, including dyed paper, gold thin film, and amorphous silicon, with the top layer even a solid

Highly Efficiently Delaminated Single-Layered MXene Nanosheets with Large Lateral Size

Single layered Ti₃C₂(OH)₂ nanosheets have been successfully fabricated by etching its Ti₃AlC₂ precursor with KOH in the presence of a small amount of water. The OH group replaced the Al layer within the Ti₃AlC₂ structure during etching, and Ti₃C₂(OH)₂ nanosheets could be easily and efficiently achieved through a simple washing process. The delaminated single-layered nanosheets are clearly revealed by atomic force microscopy to be several micrometers in lateral size. Interestingly, the exfoliated Ti₃C₂(OH)₂ nanosheets could be restacked to form a new layer-structured material after drying. When redispersing this restacked Ti₃C₂(OH)₂ materials in water again, it could be re-delaminated easily only after shaking for several hours. The easy delamination and restacking properties, coupled with intrinsic metallic conductivity and hydrophilicity, make it an ideal two-dimensional building block for fabricating a wide variety of functional materials

Ru-Catalyzed Isomerization Provides Access to Alternating Copolymers via Ring-Opening Metathesis Polymerization

We describe an isomerization–alternating ROMP protocol that gives linear copolymers with rigorous sequence alternation. Bicyclo[4.2.0]­oct-7-ene-7-carboxamides of primary amines are isomerized in the presence of (3-BrPyr)₂Cl₂(H₂IMes)­RuCHPh to the corresponding bicyclo[4.2.0]­oct-1(8)-ene-8-carboxamides in which the olefinic bond is tetrasubstituted. The <i>isomerized</i> amides undergo alternating ring-opening metathesis polymerization with cyclohexene to provide soluble and linear copolymers with molecular weights up to ∼130 kDa. This process provides efficient entry to strictly alternating copolymers that can display diverse functional groups

Self-Templated Synthesis of Porous Ni(OH)₂ Nanocube and Its High Electrochemical Performance for Supercapacitor

Porous Ni­(OH)₂ nanocubes were successfully fabricated by a simple self-sacrificial-template protocol using Ni–Co Prussian blue analogue (PBA) as precursor. When treated with NaOH, the simultaneous corrosion of Ni–Co PBA precursor and formation of amorphous Ni­(OH)₂ resulted in porous Ni­(OH)₂ nanocubes with uniform size of about 100 nm. Due to the large specific surface area and unique regular porous structure, the as-prepared materials showed large specific capacitance, relatively stable rate capability and long cycle stability when used as electrode materials for supercapacitors. With the voltage between 0.00 and 0.45 V versus Ag/AgCl, the specific capacitance can achieve 1842 F/g at a current density of 1 A/g

Rational design of liquid metal organic frameworks for the enhanced CO2 absorption and their photocatalytic reduction

Metal organic frameworks (MOFs) has been widely investigated as co-catalysts for photocatalysis owing to their unique property for controlling the reaction kinetics. They are generally presented in a solid state. Recent studies have presented MOF in the liquid phase, meanwhile preserving the framework structure. Acting as a co-catalyst, significantly improved efficiency has been realized for photocatalytic CO2 reduction. This concept article focuses on the chemical principle of liquid MOF (LMOF). Their applications in CO2 adsorption and the photocatalytic CO2 reduction have been discussed with showing key examples. In addition, the other relevant applications of LMOF have been presented. </p

DNA isolated from leaf discs from three crops.

Molecular breeding methods, such as marker-assisted selection and genomic selection, require high-throughput and cost-effective methods for isolating genomic DNA from plants, specifically from crop tissue or seed with high polysaccharides, lipids, and proteins. A quick and inexpensive high-throughput method for isolating genomic DNA from seed and leaf tissue from multiple crops was tested with a DNA isolation method that combines CTAB extraction buffer and lab-made SA-coated magnetic nanoparticles. This method is capable of isolating quality genomic DNA from leaf tissue and seeds in less than 2 hours with fewer steps than a standard CTAB extraction method. The yield of the genomic DNA was 582–729 ng per 5 leaf discs or 216–1869 ng per seed in soybean, 2.92–62.6 ng per 5 leaf discs or 78.9–219 ng per seed in wheat, and 30.9–35.4 ng per 5 leaf discs in maize. The isolated DNA was tested with multiple molecular breeding methods and was found to be of sufficient quality and quantity for PCR and targeted genotyping by sequencing methods such as molecular inversion probes (MIPs). The combination of SA-coated magnetic nanoparticles and CTAB extraction buffer is a fast, simple, and environmentally friendly, high-throughput method for both leaf tissues and seed(s) DNA preparation at low cost per sample. The DNA obtained from this method can be deployed in applied breeding programs for marker-assisted selection or genomic selection.</div