Separation by Flotation

There has been much recent activity in the theory and application of separation by flotation, both in the United. States and abroad. This review primarily addresses new developments in foam flotation, colloid flotation and precipitate flotation. The work in ore flotation represents a major effort and would itself require a lengthy article. Work from ore flotation which significantly impacts on the areas of interest listed above is included here, however. Foam separation of biological materials and the microflotation of bacteria are not routinely discussed in this review. A few recent review articles on these areas are included at the end of the Review Articles and Books Section to afford the interested reader a start on that literature. The development and use of flotation separation techniques for waste treatment and water reuse over the last few years are included in this article.     

Correlation of the Solubilizing Abilities of 1-Butyl-1-methyl-pyrrolidinium Tris(pentafluoroethyl)trifluorophosphate, 1-Butyl-1-methylpyrrolidinium Triflate and 1-Methoxyethyl-1-methylmorpholinium Tris(pentafluoroethyl)trifluorophosphate

Chromatographic retention data were measured for a wide range of organic solutes on 1-butyl-1-methylpyrolidinium tris(pentafluoroethyl)trifluorophosphate ([BMPyrr]⁺[FAP]^?), 1-butyl-1-methylpyrrolidinium triflate, ([BMPyrr]⁺[Trif]^?), and 1-methoxyethyl-1-methylmorpholinium tris(pentafluoroethyl)trifluorophosphate, ([MeoeMMorp]⁺[FAP]^?), stationary phases at (323, 353 and 383) K. The measured retention factors were combined with published infinite dilution activity coefficient and gas-to-water partition coefficient data to yield gas-to-anhydrous ionic liquid (IL) and water-to-anhydrous IL partition coefficients. The three sets of partition coefficients were analyzed using the Abraham model. The derived Abraham model correlations describe the observed gas-to-IL (log₁₀ K) and water-to-IL (log₁₀ P) partition coefficient data to within average standard deviations of about 0.11 and 0.15 log₁₀ units, respectively.     

Boronate Ligands in Materials: Determining Their Local Environment by Using a Combination of IR/Solid‐State NMR Spectroscopies and DFT Calculations

Boronic acids (R‐B(OH)₂) are a family of molecules that have found a large number of applications in materials science. In contrast, boronate anions (R‐B(OH)₃^?) have hardly been used so far for the preparation of novel materials. Here, a new crystalline phase involving a boronate ligand is described, Ca[C₄H₉‐B(OH)₃]₂, which is then used as a basis for the establishment of the spectroscopic signatures of boronates in the solid state. The phase was characterized by IR and multinuclear solid‐state NMR spectroscopy (¹H, ¹³C, ¹¹B and ⁴³Ca), and then modeled by periodic DFT calculations. Anharmonic OH vibration frequencies were calculated as well as NMR parameters (by using the Gauge Including Projector Augmented Wave—GIPAW—method). These data allow relationships between the geometry around the OH groups in boronates and the IR and ¹H NMR spectroscopic data to be established, which will be key to the future interpretation of the spectra of more complex organic–inorganic materials containing boronate building blocks.     

The use of immobilised metal affinity chromatography (IMAC) to compare expression of copper-binding proteins in control and copper-exposed marine microalgae

Toxicity of metals to aquatic organisms is dependent on both external factors, such as exposure concentration and water quality parameters, and intracellular processes including specific metal-binding sites and detoxification. Current models used to predict copper toxicity in microalgae do not adequately consider these intracellular processes. This study compared the copper-binding proteins from four species of marine microalgae, Dunaliella tertiolecta, Tetraselmis sp., Phaedactylum tricornutum and Ceratoneis closterium, in controls (no added copper) and following a 72-h exposure to copper (sufficient to inhibit growth by approximately 50 %). Cells were lysed by sonication, which was optimised to obtain 54–94 % cell rupture for the different algae. Cell lysates were processed by immobilised metal affinity chromatography (IMAC) using Cu²⁺ as the bound metal (i.e. Cu-IMAC). Bound proteins were subsequently analysed by SDS-PAGE, comparing proteins recovered from algae that were exposed to copper versus untreated control cells. Individual proteins for which copper exposure resulted in changes to proteins present were excised from gels and further analysed by nano LC ESI-MS/MS; proteins were identified using the Mascot database. Proteins identified in this way included heat-shock proteins, rubisco, α- and β-tubulins and ATP synthase (β subunit). The results established that Cu-IMAC is a useful approach to identify proteins involved in copper binding in algae. This study identified several proteins that may play an active role in responses to copper toxicity in marine microalgae.

Coating Cellulosic Material with Ag Nanowires to Fabricate Wearable IR-Reflective Device for Personal Thermal Management: The Role of Coating Method and Loading Level

Textiles coated with silver nanowires (AgNWs) are effective at suppressing radiative heat loss without sacrificing breathability. Many reports present the applicability of AgNWs as IR-reflective wearable textiles, where such studies partially evaluate the parameters for practical usage for large-scale production. In this study, the effect of the two industrial coating methods and the loading value of AgNWs on the performance of AgNWs-coated fabric (AgNWs-CF) is reported. The AgNWs were synthesized by the polyol process and applied onto the surface of cotton fabric using either dip- or spray-coating methods with variable loading levels of AgNWs. X-ray diffraction, scanning electron microscopy (SEM), infrared (IR) reflectance, water vapor permeability (WVP), and electrical resistance properties were characterized. The results report the successful synthesis of AgNWs with a 30 μm length. The results also show that the spray coating method has a better performance for reflecting the IR radiation to the body, which increases with a greater loading level of the AgNWs. The antibacterial results show a good inhibition zone for cotton fabric coated by both methods, where the spray-coated fabric has a better performance overall. The results also show the coated fabric with AgNWs maintains the level of fabric breathability similar to control samples. AgNWs-CFs have potential utility for cold weather protective clothing in which heat dissipation is attenuated, along with applications such as wound dressing materials that provide antibacterial protection.     

Shear zones and wall slip in the capillary flow of concentrated colloidal suspensions

We image the flow of a nearly random close packed, hard-sphere colloidal suspension (a "paste") in a square capillary using confocal microscopy. The flow consists of a "plug" in the center while shear occurs localized adjacent to the channel walls, reminiscent of yield-stress fluid behavior. However, the observed scaling of the velocity profiles with the flow rate strongly contrasts yield-stress fluid predictions. Instead, the velocity profiles can be captured by a theory of stress fluctuations originally developed for chute flow of dry granular media. We verified this both for smooth and rough walls.     

Biological and physical properties of pulsed-Laser-deposited zirconia/hydroxyapatite on titanium: In vitro study

Coating dental implants with hydroxyapatite (HA) may give certain advantages such as active encouragement of new bone growth, a lower rejection rate, and an improved long-term prosthesis fixation. This study examined the mechanical and biological properties of titanium alloy implant cores with an interlayer of zirconia and a coating of HA created using pulsed Laser deposition (PLD). The thickness of the zirconia layer was 50–100 nm, and the HA layer was ～600 nm. The crystallinity, morphology, wettability, and Ca/P ratio of the HA layer were investigated by electron microscopy, X-ray diffraction, goniometric measurement of contact angle, and wavelength dispersive X-ray analysis. The physical tests indicated adequate mechanical properties and a satisfactory adhesion to a titanium core modified with zirconia and HA. Cell proliferation and metabolic activity of human embryonal lung fibroblasts were determined using counting of harvested cells and providing an MTT assay. it was demonstrated that none of the samples were cytotoxic and their surfaces promoted cell colonization. PLD was found to be a promising method of applying coatings to a metal core for dental implants, and the in vitro biological tests suggest that the crystalline HA coating can improve the biological properties of titanium covered with zirconia.     

Assessing signal enhancement in distant dipolar field-based sequences

The possibility of improving the signal-to-noise efficiency of NMR signal refocused by long-range dipolar interactions has been discussed recently [R.T. Branca, G. Galiana, W.S. Warren, Signal enhancement in CRAZED experiments, J. Magn. Reson. 187 (2007) 38-43]. For systems where T(1)>T(2), by including an extra radio-frequency pulse in a standard CRAZED sequence, it is possible to increase the available signal by exploiting its sensitivity to T(1) relaxation. Here, we use analytical calculations to investigate the source of this improved signal and determine the maximum enhancement provided by the method.     

Aberration-free optical refocusing in high numerical aperture microscopy

We describe a method of optical refocusing for high numerical aperture (NA) systems that is particularly relevant for confocal and multiphoton microscopy. This method avoids the spherical aberration that is common to other optical refocusing systems. We show that aberration-free images can be obtained over an axial scan range of 70 mum for a 1.4 NA objective lens. As refocusing is implemented remotely from the specimen, this method will enable high axial scan speeds without mechanical interference between the objective lens and the specimen.     

Sulfur‐Functionalized Graphene Oxide by Epoxide Ring‐Opening

The treatment of graphene oxide (GO) with potassium thioacetate followed by an aqueous work‐up yields a new material via the ring‐opening of the epoxide groups. The new material is a thiol‐functionalized GO (GO‐SH) which is able to undergo further functionalization. Reaction with butyl bromide gives another new material, GO‐SBu, which shows significantly enhanced thermal stability compared to both GO and GO‐SH. The thiol‐functionalized GO material showed a high affinity for gold, as demonstrated by the selective deposition of a high density of gold nanoparticles.