On the development of colloidal nanoparticles towards multifunctional structures and their possible use for biological applications

In this Review, we describe the synthesis of high-quality colloidal nanoparticles in organic solvents, the mechanisms by which they can be transferred into aqueous solution, and some of their applications in biology. In particular, we will place emphasis on the creation of multifunctional nanoparticles or nanoparticle assemblies.     

微滤膜破乳技术的研究

基于膜法破乳技术的研究进展,选择了水＋正丁醇,水＋煤油以及水＋煤油＋30％TBP（磷酸三丁酯）多种体系,研究了影响破乳效果的重要参数透过压,体系性质和膜孔径等对透过液通量和透过液水相含油量的影响,实验结果表明,膜法破乳是一种很有效的破乳技术,对于不同体系的乳液均有较好的通用性,膜法破乳过程受透过压和膜孔的影响较大,随着透过的增加,透过液通过量增加,透过液中水相的油含量也随之增加,膜孔径的增大有利于透过液通量的提高,当然在相同的透过压作用下透过渡水相的含油量也会随之增加,但控制较低的透过压时,水中的油含量可以得到较好的控制。     

Oxidized graphene in ionic liquids for assembling chemically modified electrodes: a structural and electrochemical characterization study

Dispersions of graphene oxide (GO) nanoribbons in ionic liquids, ILs (either 1-butyl-3-methylimidazolium chloride (BMIM-Cl-) or 1-butylpyridinium chloride (-Bupy-Cl-)) have been used to assemble modified screen printed electrodes (SPEs). The graphene oxide/ionic liquid dispersions have been morphologically and structurally characterized by the use of several techniques: X-ray photoelectron spectroscopy (XPS), Fourier transform-infrared (FT-IR) spectroscopy, high-resolution-transmission electron microscopy (HR-TEM). The assembled modified SPEs have then been challenged with various compounds and compared to several electro-active targets. In all cases high peak currents were detected, as well as significant potential shifts, especially in the detection of catecholamines and NADH, compared with the bare SPE and the conventional electrodes, such as glassy carbon (GC) and highly oriented pyrolitic graphite (HOPG). This opens the way to the assembly of new types of sensors and biosensors. The enhanced performances observed are attributed to electrocatalytic effects related to the high electrode surface area, to oxygen-assisted electron transfer, as well as to the disordering effect of the ILs, this latter related to the favorable π-π interactions with the ILs and the GO plane.     

Changes in the fundamental absorption edge of cellulose nitrate and its possible use for radiation dosimetry

The induced changes in the absorption edge and optical density by -irradiation was measured for cellulose nitrate (CN). The optical absorption edge of CN is accurately determined as a function of absorbed dose up to 67.5 kGy. The results obtained show that the absorption edge and the optical density at a 520 nm wavelength were changed to a lower value by -irradiation. The post-irradiation stability of the films under different conditions were studied. The results suggest the possible use of a cellulose nitrate film as a dosimeter for absorbed doses up to 67.5 kGy.     

Absorption of water by room-temperature ionic liquids: effect of anions on concentration and state of water

Near-infrared (NIR) spectrometry was successfully used for the non-invasive and in situ determination of concentrations and structure of water absorbed by room-temperature ionic liquids (RTILs). It was found that RTILs based on 1-butyl-3-methylimidazolium, namely, [BuMIm]+ [BF4]-, [BuMIm]+ [bis((trifluoromethyl)sulfonyl)amide, or Tf2N]- and [BuMIm]+ [PF6]-, are hydroscopic and can quickly absorb water when they are exposed to air. Absorbed water interacts with the anions of the RTILs, and these interactions lead to changes in the structure of water. Among the RTILs studied, [BF4]- provides the strongest interactions and [PF6]- the weakest. In 24 hours, [Bu-MIm]+ [BF4]- can absorb up to 0.320 M of water, whereas [Bu-MIm]+ [PF6]- can only absorb 8.3 x 10(-2) M of water. It seems that higher amounts of water can be absorbed when the anion of the RTIL can strongly interact and hence stabilize absorbed water molecules by forming hydrogen bonds with them or inducing hydrogen bonds among water molecules. More importantly, the NIR technique can be sensitively used for the noninvasive, in situ determination of absorbed water in RTILs, without any pretreatment, and at limits of detection as low as 3.20 x 10(-3) M.     

Nonlinear dynamics in meso and nano scales: fundamental aspects and applications

This introduction to the special issue, Nonlinear dynamics in meso and nano scales: fundamental aspects and applications, gives a short overview about different contexts and current challenges posed by the emergence of nonlinearities at meso and nano characteristic sizes. It also addresses different aspects related to classical and quantum chaos. Moreover, it comments on the articles in this thematic publication, briefly summarizing their relevance in helping to understand the uprise of chaos and complex behaviour at those small scales.     

A statistical study on nanoparticle movements in a microfluidic channel

Microfluidic channels have received much attention because they can be used to control and transport nanoscale objects such as nanoparticles, nanowires, carbon nanotubes, DNA and cells. However, so far, practical channels have not been easy to design because they require very expensive fabrication and sensitive experiments. Numerical approaches can be alternatives or supplementary measures to predict the performance of new channels because they efficiently explain nanoscale multi-physics phenomena and successfully solve nanowire alignment and cell adhesion problems. In this paper, a newly updated immersed finite element method that accounts for collision force and Brownian motion as well as fluid-solid interaction is proposed, and is applied to simulate nanoparticle movements in a microfluidic channel. As part of the simulation, Brownian motion effects in a single nanoparticle focusing lens system are examined under different temperature conditions, and the resulting transport efficiencies are discussed. Furthermore, nanoparticle movements in a double focusing lens system are predicted to show the enhancement of focusing efficiency.     

Ionic liquids confined in porous matrices: Physicochemical properties and applications

Ionic liquids are emerging as important materials for applications in electrochemical devices, green chemistry etc. For device applications, ionic liquids are generally, either incorporated in polymer matrices or confined in porous matrices (giving rise to an interesting class of materials ‘Ionogels’). This review deals with the science and technological applications of ionic liquids confined in nano-pores. A comprehensive overview is given about the experimental studies dealing with the changes in the physico-chemical properties of ionic liquids like thermal phase transition, stability, dynamical behavior, optical properties etc. Recent theoretical studies highlighting the layering and structural heterogeneity of ionic liquids confined in nano-pores are also discussed. To make the review self-reading, basic ideas about ionic liquids and the phenomena of confinement are also briefly included.     

Microwave-assisted synthesis of pt nanocrystals and deposition on carbon nanotubes in ionic liquids

In this work, a simple, fast and efficient route is presented for the metal (such as Pt, Rh, etc.) nanocrystal synthesis and deposition on carbon nanotubes (CNTs) in ionic liquids (ILs) via microwave heating. In this method, inorganic salts (such as H2PtCl6.4H2O, RhCl3.2H2O, etc.) dissolved in ILs, 1,1,3,3-tetramethylguanidinium trifluoroacetate or 1,1,3,3-tetramethylguanidinium lactate, were reduced to metal nanoparticles by glycol with the aid of microwave heating, and the produced metal nanoparticles could be decorated on CNTs in the presence of CNTs in ILs. The resulting nanomaterials were characterized by means of transmission electron microscopy and X-ray diffraction. It was demonstrated that the homogeneously dispersed Pt nanocrystals with the size of 2-3 nm were obtained using H2PtCl6.4H2O as precursor, and they deposited on CNTs with the similar size when CNTs was present in ILs. This technique also can be extended to fabricate other noble metal nanocrystals (including Rh, Au, etc.) and corresponding CNT composites.     

Subsurface dopant-induced features on the Si(100)2/spl times/1:H surface: fundamental study and applications

The lack of surface states within the bandgap of the perfect Si(100)2/spl times/1:H surface opens the way to scanning tunneling microscopy studies of dopant atom sites in Si(100). Both n- and p-type dopant-induced features were observed in filled- and empty-states images. The donor (arsenic)-induced feature looks as a protrusion in both the filled and empty states images, while the acceptor (boron)-induced feature appears as a hillock in the filled states image and a depression in the empty states image. The bias dependence, depth dependence, and dopant concentration dependence of the dopant-induced features were investigated in detail. Based on scattering theory, a numerical calculation was performed to achieve a fundamental understanding of these issues. The potential application of this study for three-dimensional dopant profiling with scanning tunneling microscopy on both p- and n-type samples is discussed, and the optimal scanning condition is also suggested. This technique may be a useful metric for characterizing dopant profiles in ultra-small electronic device structures.     

A fundamental study on the impact of surface integrity by hard turning on rolling contact fatigue

Hard turning has the potential to produce favorable surface integrity that would improve component life in rolling contact. However, the effects of the process-induced residual stress profile and the white layer on rolling contact fatigue (RCF) are poorly understood. This study aims to answer the long-standing question of how residual stress and the white layer affect RCF. Based on the developed real-time RCF testing system, a series of RCF tests were conducted for hard turned AISI 52100 steel components. The test results have shown that the acoustic emission amplitude is most consistent and sensitive to fatigue damage than other AE parameters. A white layer induced by hard turning is very detrimental to RCF. A component free of a white layer can have a life six times that of a white layer component. As the white layer increases in thickness, the fatigue life decreases. Surface residual stresses and near-surface residual stress profiles are significant factors for RCF, while the depth of maximum compressive residual stress in subsurface is not critical. Surface integrity affects RCF through the mechanism of near surface damage rather than subsurface damage.     

离子液体在中孔炭中的电化学性能研究

对以离子液体(1-乙基-3-甲基咪唑四氟硼酸盐)做电解液,热固性酚醛树脂为前驱体添加纳米硅颗粒制备的中孔炭做电极构成的电化学双电层电容器的电化学行为进行了探讨.循环伏安和恒流充放电测试结果表明,离子液体在中孔炭中表现为优秀的电化学行为,大电流充放电时具有良好的电容特性,其比电容在1mA/cm2时为120F/g,充放电效率达92%,表明中孔炭非常适合离子液体电解液.     

A fundamental study of fissure sealant in dental application:in vitro adhesive tensile strength

In order to develop the sealing of pits and fissures in human enamel, a polymethylmethacrylate (PMMA) cylinder was bonded to a flattened one and to the labial enamel surface of young bovine teeth subjected to acid-etched treatment. An increase in adhesive tensile strength occurred for methyl--cyanoacrylate, one of the alkyl-cyanoacrylate adhesives tested. A larger significant difference in the release of fluoride was found in each cyanoacrylate adhesive containing 11 kinds of fluoride compounds. The value of the adhesive tensile strength at the interface of the PMMA-acid-etched bovine enamel depended on the cyanoacrylate adhesive type and the conservation conditions.     

Heterogeneity of traditional and digital media use among older adults: A six-country comparison

The concept of aged heterogeneity has been associated with older adults' ability to adapt to the digital age without a systematic empirical analysis. We analyse retired adults' (aged 62 or more) use of traditional media and their digital equivalents in six countries. First, we ask whether heterogeneity in traditional and digital media use increases with age. Second, we study to what extent gender is related to this heterogeneity, and third, the country differences in the heterogeneity of media use in later life. We analyse the 2018 data (N = 5865) of the ‘Older audiences in the digital media environment’ survey using zero-inflated negative binomial models. The results provide partial support for aged heterogeneity in connection to digital media use. Gender differences were small and stable across cohorts, except in reading printed books, which increased with age among women. Country differences in the adoption and use of traditional and digital media were large.     

The hydrothermal analogy role of ionic liquid in transforming amorphous TiO2 to anatase TiO2: elucidating effects of ionic liquids and heating method

In this study, the specific coexistence of water and ionic liquid being the lower temperature thermal annealing condition for anatase crystallization of amorphous titania at ambient pressure was found. The test ionic liquids were 1-butyl-3-methylimidazolium hexafluorophosphate and 1-butyl-3-methylimidazolium tetrafluoroborate. After deep investigation, we found that there existed an analogy between our lower temperature thermal annealing treatment system (LTTAT) and hydrothermal treatment system. In LTTAT system, the ionic liquid played an important role in driving surface crystallization of amorphous TiO₂ to the anatase phase by retaining a suitable amount of water through a dissolution–crystallization mechanism. We could observe higher hydroxyl group ratio of hydroxylated titanium compound from X-ray photoelectron spectroscopy (XPS) data during initial thermal annealing period. The self-assembly ability of ionic liquid then lead to kinetical dehydration and crystallization of hydroxylated titanium compound around it during the following annealing process. Based upon this proposition, the effects of different types of ionic liquid and its amount, temperature effect, and heating method on anatase crystallinity, characterized by X-ray diffraction (XRD), were investigated. It was found that different temperatures and microwave heating effect were observed for different types of ionic liquid. From these observations, it was pointed out that we could get better anatase crystallinity and good photodegradation performance by using the system containing ionic liquid having higher water-adsorbing ability and microwave heating annealing.     

Influence of structural variation in room-temperature ionic liquids on the selectivity and efficiency of competitive alkali metal salt extraction by a crown ether

An improved method for the preparation of 1-alkyl-3-methylimidazolium hexafluorophosphates provides a series of room-temperature ionic liquids (RTILs) in which the 1-alkyl group is varied systematically from butyl to nonyl. For competitive solvent extraction of aqueous solutions of alkali metal chlorides with solutions of dicyclohexano-18-crown-6 (DC18C6) in these RTILs, the extraction efficiency generally diminished as the length of the 1-alkyl group was increased. Under the same conditions, extraction of alkali metal chlorides into solutions of DC18C6 in chloroform, nitrobenzene, and 1-octanol was undetectable. The extraction selectivity order for DC18C6 in the RTILs was K+ > Rb+ > Cs+ > Na+ > Li+. As the alkyl group in the RTIL was elongated, the K+/ Rb+ and K+/Cs+ selectivities exhibited general increases with the larger enhancement for the latter. For DC18C6 in 1-octyl-3-methylimidazolium hexafluorophosphate, the alkali metal cation extraction selectivity and efficiency were unaffected by variation of the aqueous-phase anion from chloride to nitrate to sulfate.     

Preconcentration of Sr(II) by extraction and sorption with carbamoyl phosphine oxides in the presence of ionic liquids

Extraction of microamounts of Sr(II) from aqueous solutions with solutions of carbamoyl phosphine oxides in the presence of ionic liquids was studied. The influence of the structure of the extractants and ionic liquids on the efficiency of the Sr(II) extraction was examined, and the stoichiometry of the extractable complexes was determined. The possibility of preconcentrating Sr(II), and also U(VI), Th(IV), and REE(III) from aqueous solutions with a complexing sorbent prepared by noncovalent immobilization of diphenyl( diethylcarbamoylmethyl)phosphine oxide and 1-butyl-3-methylimidazolium bis[(trifluoromethyl)-sulfonyl]imide on a macroporous polymer matrix was demonstrated.     

Subsurface particulate film formation in softenable substrates: Present status and possible new applications

The status of our knowledge of subsurface particulate film formation in softenable substrates is reviewed. Particular emphasis is given to recent developments in our understanding of the formation mechanism, which has progressed via both experiment and theory. Subsurface particulate monolayer formation is now appreciated as a very general phenomenon for most inorganic materials in combination with organic polymer substrates; partially embedded structures are generally formed by organic particulate materials. These configurations are explained by thermodynamic formulations involving the surface and interfacial tensions. With the convenient technique of vacuum deposition, subsurface formation is generally limited to low melting point inorganic materials, and even with these materials is further limited to certain ranges of substrate temperature and deposition rate. These limitations can be ascribed to either sinking rate or growth mode limitations, and calculations are in excellent quantitative agreement with experimental data. When vacuum deposition onto soft substrates does not form a subsurface structure, the resulting above-surface film generally grows in the rare Stranski-Krastanov mode. Based on our present understanding, several possible new applications of these unique subsurface structures (in addition to their important photographic uses) are proposed. These include techniques for improving the substrate adhesion of many inorganic and organic evaporated films, as well as uses as one-step optical recording media and as solar absorbers. It seems likely that other applications will arise as the existence of these structures becomes more widely known.     

Sessile droplet formation in the laser-induced forward transfer of liquids: A time-resolved imaging study

The formation process of sessile droplets in the laser-induced forward transfer of aqueous solutions was analyzed through time-resolved imaging. At the irradiation conditions which lead to the deposition of well-defined droplets, a cavitation bubble is generated in the laser irradiated area. Such bubble evolves into a high-speed liquid jet which propagates towards the receptor solid substrate. Once the jet impinges on the receptor substrate, liquid gently starts accumulating on the impact position, and the growth of a sessile droplet initiates. In a first stage, which only lasts a few microseconds, the forming droplet suffers a fast spreading process. Then, the jet continues feeding the forming droplet for some hundreds of microseconds, but the droplet diameter remains constant, and thus the contact angle increases. Finally, liquid feeding stops due to jet breakup, and the sessile droplet initiates a slow relaxation process in which its contact angle diminishes and its diameter increases. This deposition process results in the deposition of a single sessile droplet up to donor film-receptor substrate distances of the order of the millimeter. At higher separations, satellite droplets appear, and at even higher separations only randomly distributed small droplets are deposited.