Rapid and Controllable Digital Microfluidic Heating by Surface Acoustic Waves

Fast and controllable surface acoustic wave (SAW) driven digital microfluidic temperature changes are demonstrated. Within typical operating conditions, the direct acoustic heating effect is shown to lead to a maximum temperature increase of about 10 °C in microliter water droplets. The importance of decoupling droplets from other on‐chip heating sources is demonstrated. Acoustic‐heating‐driven temperature changes reach a highly stable steady‐state value in ≈3 s, which is an order of magnitude faster than previously published. This rise time can even be reduced to ≈150 ms by suitably tailoring the applied SAW‐power excitation profile. Moreover, this fast heating mechanism can lead to significantly higher temperature changes (over 40 °C) with higher viscosity fluids and can be of much interest for on‐chip control of biological and/or chemical reactions.     

Modified interfacial tensions measured in situ in ternary polymer blends demonstrating partial wetting

An in situ Neumann triangle-focused ion beam-atomic force microscopy (NT-FIB-AFM) method has been used to measure modified PS/HDPE interfacial tensions in ternary PS/PP/HDPE blends prepared by melt mixing and demonstrating partial wetting. The ternary blend was modified with SEB, SB and SEBS copolymers. Results related to the position of the PS droplet at the interface show that a symmetrical diblock copolymer is somewhat more efficient in decreasing the interfacial tension compared to an asymmetrical one of similar molecular weight, while the SEBS triblock copolymer appears to have no effect at all. Using the NT-FIB-AFM method, the lowest modified PS/HDPE interfacial tension is 3.0 ± 0.4 mN/m for the symmetric diblock, compared to 4.2 ± 0.6 mN/m (N = 34) for the unmodified interface. This corresponds to an apparent areal density in SEB copolymer equal to 0.16 ± 0.03 molecules/nm², which is near reported saturation values. By varying the concentration of the copolymer, an emulsification curve reporting the value of the PS/HDPE modified interfacial tension as a function of the apparent areal density of the copolymer at the PS/HDPE interface has been obtained. The interfacial tension values obtained by the NT-FIB-AFM approach are significantly higher than the 0.5 ± 0.2 mN/m (N = 3) result obtained by using the classical breaking thread method with the same materials. This discrepancy does not appear to be due to a poor migration of the copolymer to the PS/HDPE interface, but could instead be attributed to the interfacial elasticity of the compatibilized interface, a phenomena that has not been accounted for so far in experimental studies on the morphology of compatibilized multicomponent polymer blends.     

Recapitulating Antioxidant and Antibacterial Compounds into a Package for Tissue Regeneration: Dual Function Materials with Synergistic Effect

Oxidative damage and infection can prevent or delay tissue repair. Moreover, infection reinforces reactive oxygen species (ROS) formation, which makes the wound's condition even worse. Therefore, the need for antioxidant and antibacterial agents is felt for tissue regeneration. There are emerging up-and-coming biomaterials that recapitulate both properties into a package, offering an effective solution to turn the wound back into a healing state. In this article, the principles of antioxidant and antibacterial activity are summarized. The review starts with biological aspects, getting the readers to familiarize themselves with tissue barriers against infection. This is followed by the chemistry and mechanism of action of antioxidant and antibacterial materials (dual function). Eventually, the outlook and challenges are underlined to provide where the dual-function biomaterials are and where they are going in the future. It is expected that the present article inspires the designing of dual-function biomaterials to more advanced levels by providing the fundamentals and comparative points of view and paving the clinical way for these materials.     

Nitrogen addition influences formation of aroma compounds,volatile acidity and ethanol in nitrogen deficient media fermented by Saccharomyces cerevisiae wine strains

The effects of nitrogen addition into nitrogen deficient/depleted media on the release of aroma compounds post-fermentation were investigated in three commercial yeast strains of Saccharomyces cerevisiae which highlight the yeast strain effect as well as nitrogen effects. By comparing the two timings of nitrogen addition, prior to fermentation or later at stationary phase (72 h), it was shown that nitrogen addition at stationary phase significantly decreases ethanol and acetic acid formation and significantly increases the following compounds: 2-phenylethanol, ethyl isobutyrate, 2-phenylethyl acetate, ethyl 2-methylbutyrate and ethyl propionate in the three strains, and also isovaleric acid, isoamyl alcohol and ethyl isovalerate in both PYCC4072 and UCD522. The strain EC1118 produced significantly less medium chain fatty acids, hexanoic, octanoic and decanoic acids and their respective esters after nitrogen addition. Therefore, timing of nitrogen addition to a ferment media can vary the concentration of certain aroma compound and might provide a means for varying wine composition.     

Will Model-based Definition replace engineering drawings throughout the product lifecycle? A global perspective from aerospace industry

The Model-based Definition (MBD) approach is gaining popularity in various industries. MBD represents a trend in Computer-aided Design (CAD) that promises reduced time-to-market and improved product quality. Its main goal is to improve and accelerate the design, manufacturing and inspection processes by integrating drawing annotations directly onto a 3D model, therefore obviating the need to generate engineering drawings. However, its implementation throughout the whole product lifecycle has not yet been fully adopted. Traditional engineering drawings still play an essential part in the capture and distribution of non-geometric information. Based on thirty-four interviews conducted within the Engineering, Drafting, Configuration Management, Airworthiness and Certification, Manufacturing, Inspection and Knowledge Management departments from two Canadian Aerospace companies, the objective of this paper is to report on the main barriers that need to be overcome in order to fully implement the MBD initiative. In addition, the necessary elements and specific requirements needed to evaluate the capacities of emergent tools are proposed.     

A distributed semantic network model for a collaborative intelligent system

A methodology based on topology theory to model a semantic network for a collaborative system is given. This framework is used to support the creation of a semantic network and to define the associated intelligent cooperative system. Our methodology is illustrated via a set of agents whose knowledge-base is a semantic network. By a series of functions applied on a base of entities, issued from the application domain, a family of sets are synthesized with their subspaces correlated. The resultant subspaces and their relations form a network of elementary and complex concepts that can be naturally represented with the IDEF1x language. A prototype Multi-Agent System (MAS), set up with the Zeus platform,¹ was developed for the Process Plan domain, which was used as a case study. Full correspondence among the subspaces, the semantic network IDEF1x information model and the MAS implementation is obtained by employing this framework.     

A septin-based hierarchy of proteins required for localized deposition of chitin in the Saccharomyces cerevisiae cell wall

Just before bud emergence, a Saccharomyces cerevisiae cell forms a ring of chitin in its cell wall; this ring remains at the base of the bud as the bud grows and ultimately forms part of the bud scar marking the division site on the mother cell. The chitin ring seems to be formed largely or entirely by chitin synthase III, one of the three known chitin synthases in S. cerevisiae. The chitin ring does not form normally in temperature-sensitive mutants defective in any of four septins, a family of proteins that are constituents of the "neck filaments" that lie immediately subjacent to the plasma membrane in the mother-bud neck. In addition, a synthetic-lethal interaction was found between cdc12-5, a temperature-sensitive septin mutation, and a mutant allele of CHS4, which encodes an activator of chitin synthase III. Two-hybrid analysis revealed no direct interaction between the septins and Chs4p but identified a novel gene, BNI4, whose product interacts both with Chs4p and Cdc10p and with one of the septins, Cdc10p; this analysis also revealed an interaction between Chs4p and Chs3p, the catalytic subunit of chitin synthase III. Bni4p has no known homologues; it contains a predicted coiled-coil domain, but no other recognizable motifs. Deletion of BNI4 is not lethal, but causes delocalization of chitin deposition and aberrant cellular morphology. Overexpression of Bni4p also causes delocalization of chitin deposition and produces a cellular morphology similar to that of septin mutants. Immunolocalization experiments show that Bni4p localizes to a ring at the mother-bud neck that lies predominantly on the mother-cell side (corresponding to the predominant site of chitin deposition). This localization depends on the septins but not on Chs4p or Chs3p. A GFP-Chs4p fusion protein also localizes to a ring at the mother-bud neck on the mother-cell side. This localization is dependent on the septins, Bni4p, and Chs3p. Chs3p, whose normal localization is similar to that of Chs4p, does not localize properly in bni4, chs4, or septin mutant strains or in strains that accumulate excess Bni4p. In contrast, localization of the septins is essentially normal in bni4, chs4, and chs3 mutant strains and in strains that accumulate excess Bni4p. Taken together, these results suggest that the normal localization of chitin synthase III activity is achieved by assembly of a complex in which Chs3p is linked to the septins via Chs4p and Bni4p.