Effective Synthesis of N‐Arylformamide from α‐Halo‐N‐arylacetamides

A convenient synthetic method for N‐arylformamide derivatives was successfully developed by reacting α‐iodo‐N‐arylacetamides with formamide. This method was applicable to α‐iodo‐N‐arylacetamide substrates bearing electron‐donating or electron‐withdrawing groups, N‐(benzo[d][1,3]dioxol‐5‐yl)‐2‐iodoacetamide, 2‐iodo‐N‐(pyridin‐2‐yl)acetamide, and 2‐iodo‐N‐(naphthalen‐4‐yl)acetamide to give the corresponding N‐arylformamides in moderate to excellent yields (65–94%). A plausible mechanism was proposed to account for the new transformation.     

Colorimetric assay for cyanide and cyanogenic glycoside using polysorbate 40-stabilized gold nanoparticles

This study describes a simple method for the selective and sensitive detection of cyanide and endogenous biological cyanide using polysorbate 40-stabilized gold nanoparticles.     

Electrokinetic flow in an elliptic microchannel covered by ion-penetrable membrane

The electrokinetic flow of an electrolyte solution in an elliptical microchannel covered by an ion-penetrable, charged membrane layer is examined theoretically. The present analysis extends previous results in that a two-dimensional problem is considered, and the system under consideration simulates the flow of a fluid, for example, in a microchannel of biological nature such as vein. The electroosmostic volumetric flow rate, the total electric current, the streaming potential, and the electroviscous effect of the system under consideration are evaluated. We show that, for a constant hydraulic diameter, the variations of these quantities as a function of the aspect ratio of a microchannel may have a local minimum or a local maximum at a medium level of ionic strength, which depends on the thickness of the membrane layer. For a constant cross-sectional area, the electroosmostic volumetric flow rate, the total electric current, and the streaming potential increase monotonically with the increase in the aspect ratio, but the reverse is true for the electroviscous effect.     

Enhanced electrodeposition of indium hexacyanoferrate thin films through improved plating solution stability

An ordinary plating solution for indium hexacyanoferrate (InHCF) thin film deposition, mainly composed of equal concentrations of In³⁺ and [Fe(CN)₆]^3–, usually forms precipitates rapidly when either concentration is higher than few millimolar. This contributes to the plating solution's instability. Moreover, electrodeposited capacities are limited accordingly. In this work, the plating solution's stability and the electrodeposition of InHCF were greatly enhanced by adding a large amount of K⁺ and/or H⁺. It was found that a 10-mM plating solution added with 1 M HCl and 1 M KCl could be stored as fresh over a one-week period, whereas an unmodified plating solution became useless within a couple of minutes. Also, such cationic additions, especially adding H⁺, increased the electrodeposited capacity ca. 18 times at least, as compared with that obtained from the unmodified plating solution. Furthermore, related enhancing mechanisms were proposed and verified. To sum up, this study offers a means for better InHCF electrodeposition and should promote the applications of InHCF films. Electronic Publication     

Diffusiophoresis in suspensions of highly charged soft particles

Diffusiophoresis phenomenon of aoft particles suspended in binary electrolyte solutions is explored theoretically in this study based on the spherical cell model, focusing on the chemiphoresis component in absence of diffusion potential. Both the electrostatic and hydrodynamic aspects of the boundary confinement, or steric effect, due to the presence of neighboring particles are examined extensively under various electrokinetic conditions. Significant local extrema are found in mobility profiles expressed as functions of the Debye length in general, synchronized with the strength of the motion-inducing double layer polarization. Moreover, a seemingly peculiar phenomenon is observed that the soft particles may move faster in more concentrated suspensions. The competition between the simultaneous enhancement of the motion-inducing electric driving force and the motion-retarding hydrodynamic drag force from the boundary confinement effect of the neighboring particles is found to be responsible for it. The above findings are also demonstrated experimentally in a very recent study on the diffusiophoretic motion of soft particles through porous collagen hydrogels. The results presented here are useful in various practical applications of soft particles like drug delivery.     

Two-phase flow pressure change subject to sudden contraction in small rectangular channels

This study investigates the pressure change and flow pattern subject to the influence of sudden contractions. The air and water mixture flows from small rectangular channels (2 × 4, 2 × 6, 4 × 4 and 4 × 6 mm, respectively) into a 2 mm diameter tube. The total mass flux (G) ranges from 100 to 700 kg/m² s with gas quality (x) being varied from 0.001 to 0.8. In general the contraction pressure change increases with the rise of mass flux, and gas quality but an unique deflection of contraction pressure change pertaining to liquid vena contracta at a very low gas quality is encountered at a very low gas quality in the 4 ± 6 mm test section. For a low gas quality, elongated bubble prevails after the contraction, yet the size of elongated bubbles is reduced when the aspect ratio is increased. Comparisons amid the pressure change data of this study and available literature data with the predictions of existing model/correlations indicate that none of them can accurately predict the data. It is found that the influence of surface tension and outlet tube size, or equivalently the Bond number plays a major role for the departure of various models/correlations. Among the models/correlations being examined, the homogeneous model shows a little better than the others. Hence by taking account the influences of gas quality, Bond number, Weber number and area contraction ratio into the homogeneous model, a modified homogeneous correlation is proposed that considerably improves the predictive ability over existing correlations with a mean deviation of 30% to all the data.     

Crystallization kinetics and crystallization behavior of syndiotactic polystyrene/clay nanocomposites

We investigated the effects of montmorillonite (clay) on the crystallization kinetics of syndiotactic polystyrene (sPS) with isothermal differential scanning calorimetry analyses. The clay was dispersed into the sPS matrix via melt blending on a scale of 1–2 nm or up to about 100 nm, depending on the surfactant treatment. For a crystallization temperature of 240 °C, the isothermal crystallization data were fitted well with the Avrami crystallization equation. Crystallization data on the kinetic parameters (i.e., the crystallization rate constant, Avrami exponent, clay content, and clay/surfactant cation‐exchange ratio) were also investigated. Experimental results indicated that the crystallization rate constant of the sPS nanocomposite increased with increasing clay content. The clay played a vital role in facilitating the formation on the thermodynamically more favorable all‐β‐form crystal when the sPS was melt‐crystallized. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 2097–2107, 2001     

Polymerization and nanocomposites properties of multifunctional methylmethacrylate POSS

Thermally induced polymerization of multifunctional methylmethacrylate POSS (MMA‐POSS) was studied in this work for preparation of polymer/POSS nanocomposites. The polymerization of MMA‐POSS could be promoted with benzoyl peroxide (BPO). Self‐assembly of POSS into a layer‐by‐layer structure in the MMA‐POSS polymer (TP‐MMA‐POSS) is observed with a transmission electron microscopy. An ultra‐low‐k value of about 1.85 is measured with TP‐MMA‐POSS. In addition, polyimide‐POSS nanocomposites are also prepared. These nanocomposites demonstrate good homogeneity and enhanced mechanical properties. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 5157–5166, 2008     

Sorption of low-level radwaste by Spirulina

The feasibility of using spirulina as adsorbent for the treatment of low-level liquid radwaste is studied. The experimental results indicate that the sorption capacity of spirulina is good for the di- and trivalent metallic ions at pH 3-7, but rather poor for the mono-valent metallic ions and non-metallic ions. Some factors affecting metal ion uptake by spirulina such as the content of detergent, sodium ion in liquid radwaste and the stability of spirulina under gamma irradiation were also investigated.