Changes in the Structural Dimensionality of Selenidostannates in Ionic Liquids: Formation,Structures, Stability,and Photoconductivity

In situ transformations of selenidostannate frameworks in ionic liquids (ILs) were initiated by treatment of the starting phase K₂[Sn₂Se₅] and the consecutive reaction products by means of temperature increase and/or amine addition. Along the reaction pathway, the framework dimensionalities of the five involved selenidostannate anions develop from 3D to 1D and back, both in top‐down and bottom‐up style. Addition of ethane‐1,2‐diamine (en) led to the reversion of the 2D→1D step from 2D‐{[Sn₂₄Se₅₆]^16?} to 1D‐{[Sn₆Se₁₄]^4?}. As rationalized by DFT investigations, the 2D anion is thermodynamically favored. Photoconductivity measurements reveal that all samples show Schottky contact behavior with absolute thresholds below 10 V. One of the samples exhibits conductive states within the energy range of visible photons.     

Shear thickening and shear-induced agglomeration of chemical mechanical polishing slurries using electrolytes

Chemical mechanical polishing is a fundamental technology used in the semiconductor manufacturing industry to polish and planarize a wide range of materials for the fabrication of microelectronic devices. During the high-shear (～1,000,000 s^?1) polishing process, it is hypothesized that individual slurry particles are driven together to form large agglomerates (≥0.5 µm). These agglomerates are believed to trigger a shear-induced thickening effect and cause defects during polishing. We examined how the addition of various monovalent salts (CsCl, KCl, LiCl, and NaCl) and electrostatic stabilizing bases (KOH, NaOH, or CsOH) influenced the slurry’s thickening behavior. Overall, as the added salt concentration was increased from 0.02 to 0.15 M, the shear rate at which the slurry thickened (i.e., the critical shear rate) decreased. Slurries with added CsCl, NaCl, and LiCl thickened at comparable shear rates (～20,000–70,000 s^?1) and, in general, followed ion hydration theory (poorly hydrated ions caused the slurry to thicken at lower shear rates). However, slurries with added KCl portrayed thickening behavior at higher critical shear rates (～35,000–100,000 s^?1) than other chloride salts. Also, slurries stabilized with CsOH thickened at higher shear rates (～90,000–140,000 s^?1), regardless of the added salt cation or concentration, than the slurries with KOH or NaOH. The NaOH-stabilized slurries displayed thickening at the lowest shear rates (～20,000 s^?1). The thickening dependence on slurry base cation indicates the existence of additional close-range structure forces that are not predicted by the Derjaguin–Landau–Verwey–Overbeek colloidal stability theory.     

Automated capillary electrophoresis with on-line preconcentration by solid phase extraction using a sequential injection manifold and contactless conductivity detection

An extension of a capillary electrophoresis instrument coupled to a sequential injection analysis manifold was developed for automated measurements with on-line solid-phase extraction preconcentration. An in-house built capacitively coupled contactless conductivity detector was employed for sensitive detection with narrow capillaries of 25 μm internal diameter. The system was assembled into standardized 19 in. frames and racks for easy transport and mobile deployment. The system can be left running unattendedly without manual intervention with good operation stability. To demonstrate the application of the system, a method for the determination of four drugs, namely ibuprofen, diclofenac, naproxen and bezafibrate, was developed with enrichment factors of up to several hundreds. Detection of the drug residues down to the nM-scale was found possible and the method was found suitable for the detection of ibuprofen in the waste water of a hospital in Hanoi.     

Influence of interfacial properties on Ostwald ripening in crosslinked multilayered oil-in-water emulsions

The influence of interfacial crosslinking, layer thickness and layer density on the kinetics of Ostwald ripening in multilayered emulsions at different temperatures was investigated. Growth rates of droplets were measured by monitoring changes in the droplet size distributions of 0.5% (w/w) n-octane, n-decane, and n-dodecane oil-in-water emulsions using static light scattering. Lifshitz-Slyozov-Wagner theory was used to calculate Ostwald ripening rates. A sequential two step process, based on electrostatic deposition of sugar beet pectin onto fish gelatin or whey protein isolate (WPI) interfacial membranes, was used to manipulate the interfacial properties of the oil droplets. Laccase was added to the fish gelatin-beet pectin emulsions to promote crosslinking of adsorbed pectin molecules via ferulic acid groups, whereas heat was induced to promote crosslinking of WPI and helix coil transitions of fish gelatin. Ripening rates of single-layered, double-layered and crosslinked emulsions increased as the chain length of the n-alkanes decreased. Emulsions containing crosslinked fish gelatin-beet pectin coated droplets had lower droplet growth rates (3.1 ± 0.3 × 10⁻²⁶ m³/s) than fish gelatin-stabilized droplets (7.3 ± 0.2 × 10⁻²⁶ m³/s), which was attributed to the formation of a protective network. Results suggest that physical or enzymatic biopolymer-crosslinking of interfaces may reduce the molecular transport of alkanes between the droplets in the continuous phase.     

Linear and nonlinear electromagnetic coupling models in vibration-based energy harvesting

This paper investigates the response of an energy harvester that uses electromagnetic induction to convert ambient vibration into electrical energy. A unique aspect of the present study is the comparison of the system's response behavior when either a linear or a physically motivated form of nonlinear coupling is applied. The motivating hypothesis for this work was that nonlinear coupling could be used to improve the performance of an energy harvester by broadening its frequency response. Combined theoretical and numerical studies investigate the harvester's response for both single and multi-frequency base excitation. Our investigations unveil regions in the parameter space where nonlinear coupling is better than linear coupling and regions where the opposite is true. The meaningful conclusion is that nonlinear coupling can sometimes be detrimental, but it can also be beneficial if properly designed into the system.     

Experimental study of hydraulic engine mounts using multiple inertia tracks and orifices: Narrow and broad band tuning concepts

Hydraulic engine mount tuning concepts with one inertia track and one decoupler are well understood. However, the dynamic response with multiple tracks or orifices is not. To overcome this void in the literature, dynamic tuning concepts of hydraulic engine mounts, with emphasis on multiple (n-)inertia tracks/orifices, are experimentally examined. A new prototype mount concept is designed, built, and experimentally evaluated in a controlled manner. Refined linear time-invariant models of fixed decoupler-type designs are developed to critically assess the dynamic stiffness measurements and to explore a family of alternate designs. Three narrowband devices are investigated for accurately predicting the frequencies corresponding to peak loss angles for the first time, in addition to examining and validating an n = 3 track mount. Two broadband devices are also successfully evaluated by tuning damping introduced by orifice-type tracks. A special broad-tuned design utilizing a controlled ‘leakage’ path flow area is then suggested, and the role of fluid resistance in achieving the desired performance is clarified. Finally, a production mount with unknown configuration is diagnosed using the proposed models with n tracks.     

An Ancestral Member of the Polysaccharide Lyase Family 2 Displays Endolytic Activity and Magnesium Dependence

Polysaccharide lyases (PLs) are enzymes that cleave glycosidic linkages in hexuronate polysaccharides, such as homogalacturonan (HG), using a β-elimination mechanism. Traditionally, PL activities on HG have been associated with catalytic calcium cofactors, unusually high pH optima, and arginine Brønstead bases. Recently, however, PL families that harness transition metal cofactors, utilize lysine and histidine Brønstead bases, and display more neutral pH optima have been described. One such family is PL2, which has members found primarily in phytopathogenic (e.g., Dickeya spp. and Pectobacterium spp.) or enteropathogenic (e.g., Yersinia spp.) bacterial species. PL2 is divided into two major subfamilies that are correlated with either an endolytic or exolytic activity. This study has focused on the activity of a PL2 member, which is not classified within either subfamily and helps to illuminate the origin of enzyme activities within the family. In addition, the role of Mg²⁺ as a preferential catalytic metal for an intracellular PL2 (PaePL2) is described. The implications for the relationship between catalytic metal selectivity and the cellular location of pectate lyase-mediated catalysis are discussed.     

A critique of the unsaturable trap model of radiation damage in metals

The unsaturable trap model, which attributes the increase of the electrical resistivity of fcc metals during electron irradiation in the temperature regime of Stage-II recovery to the trapping of Stage-I_E interstitials at impurity atoms, is shown to be in serious disagreement with the experiments, contrary to opposite statements in the literature. As shown recently, the predictions of the unsaturable trap model are independent of the dimensionality of the diffusion of the Stage-I_E interstitials. Previous attempts to rule out a one-dimensional migration of the Stage-I_E interstitials (and hence the two-interstitial model) on the basis of the alleged agreement of the unsaturable trap model with Stage-II damage curves are thus meaningless. On the contrary, it is demonstrated that the two-interstitial model accounts for minute details of the measured Stage-II damage curves in a natural way.     

Structure Evolution upon Uniaxial Drawing Skin‐ and Core‐Layers of Injection‐Molded Isotactic Polypropylene by In Situ Synchrotron X‐ray Scattering

The structure evolution of the oriented layer (skin) and unoriented layer (core) from injection‐molded isotactic polypropylene samples upon uniaxial drawing is probed by in situ synchrotron X‐ray scattering. The X‐ray data analysis approach, called “halo method”, is used to semiquantitatively identify the transformation process of crystal phase upon uniaxial drawing. The results verify the validation of the stress‐induced crystal fragmentation and recrystallization process in the deformation of the injection‐molded samples under different temperatures. Furthermore, the end of strain softening region in the engineering stress‐strain curves explicitly corresponds to the transition point from the stress‐induced crystal fragmentation to recrystallization process. Basically, the skin and core layers of the injection‐molded parts share the similar deformation mechanism as aforementioned. The stretching temperature which dramatically affects the relative strength between the entanglement‐induced tie chains and the adjacent crystalline lamellae determines the crystal structural evolution upon drawing. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2013, 51, 1618–1631