Phenol–formaldehyde–pyrolytic oil resins for wood preservation: A rheological study

The rheological properties of a phenol–formaldehyde resin containing various ratios of softwood pyrolytic oil as phenol substitute were investigated using the simple Bingham rheological model for viscoplastic fluids. Flow activation energy was determined for the various resin blends and the pyrolytic oil between room temperature and 50°C and correlations relating the flow activation energy to the weight fraction of pyrolytic oil in the resin are proposed. Apparent crosslinking activation energy with and without copper chloride used as an activator was also evaluated based on two gel time measurements between 75 and 105°C. A significant decrease in activation energy was observed for the phenol–formaldehyde resin cured with copper chloride, while the effect was less important for resins containing pyrolytic oil even when gel times were much shorter for PF‐resins. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Grating-coupled surface plasmon polaritons and waveguide modes in a silver-dielectric-silver structure

A silver-dielectric-silver structure that supports both waveguide modes and surface plasmon polaritons is explored. The upper interface between the dielectric and the silver is periodically corrugated to allow coupling of visible photons to both types of mode. Such a metallic microcavity leads to plasmonic and waveguide self-interacting bandgaps at Brillouin zone boundaries. In addition there are found other bandgaps from mode crossings within the Brillouin zone. This results specifically in a very flat photonic band due to anticrossings between a surface plasmon polariton and waveguide modes. Characterization of the observed modes in terms of their resonant electromagnetic fields is achieved by using a multilayer, multishape differential grating theory.     

Nanomaterials for efficiently lowering the freezing point of anti-freeze coolants

In this paper, we report, for the first time, the effect of the lowered freezing point in a 50% water/50% anti-freeze coolant (PAC) or 50% water/50% ethylene glycol (EG) solution by the addition of carbon nanotubes and other particles. The experimental results indicated that the nano materials are much more efficient (hundreds fold) in lowering the freezing point than the regular ionic materials (e.g., NaCl). The possible explanation for this interesting phenomenon is the colligative property of fluid and relative small size of nano material. It is quite certain that the carbon nanotubes and metal oxide nano particles could be a wonderful candidate for the nano coolant application because they could not only increase the thermal conductivity, but also efficiently lower the freezing point of traditional coolants.     

A single-step photolithographic interface for cell-free gene expression and active biochips

We have developed a biochip platform technology suitable for controlled cell-free gene expression at the micrometer scale. A new hybrid molecule, "Daisy", was designed and synthesized to form in a single step a biocompatible lithographic interface on silicon dioxide. A protocol is described for the immobilization of linear DNA molecules thousands of base pairs long on Daisy-coated surfaces with submicrometer spatial resolution and up to high densities. On-chip protein synthesis can be obtained with a dynamic range of up to four orders of magnitude and minimal nonspecific activity. En route to on-chip artificial gene circuits, a simple two-stage gene cascade was built, in which the protein synthesized at the first location diffuses to regulate the synthesis of another protein at a second location. We demonstrate the capture of proteins from crude extract onto micrometer-scale designated traps, an important step for the formation of miniaturized self-assembled protein chips. Our biochip platform can be combined with elastomeric microfluidic devices, thereby opening possibilities for isolated and confined reaction chambers and artificial cells in which the transport of products and reagents is done by diffusion and flow. The Daisy molecule and described approach enables groups not proficient in surface chemistry to construct active biochips based on cell-free gene expression.     

Understanding the hydrogen effect on pop-in behavior of an equiatomic high-entropy alloy during in-situ nanoindentation

Hydrogen embrittlement has been recognized as a serious prob-lem in the application of metallic structural materials,where hy-drogen degrades the mechanical pro...     

Delta ribozyme has the ability to cleave in transan mRNA

We report here the first demonstration of the cleavage of an mRNA in trans by delta ribozyme derived from the antigenomic version of the human hepatitis delta virus (HDV). We characterized potential delta ribozyme cleavage sites within HDV mRNA sequence (i.e. C/UGN6), using oligonucleotide binding shift assays and ribonuclease H hydrolysis. Ribozymes were synthesized based on the structural data and then tested for their ability to cleave the mRNA. Of the nine ribozymes examined, three specifically cleaved a derivative HDV mRNA. All three active ribozymes gave consistent indications that they cleaved single-stranded regions. Kinetic characterization of the ability of ribozymes to cleave both the full-length mRNA and either wild-type or mutant small model substrate suggests: (i) delta ribozyme has turnovers, that is to say, several mRNA molecules can be successively cleaved by one ribozyme molecule; and (ii) the substrate specificity of delta ribozyme cleavage is not restricted to C/UGN6. Specifically, substrates with a higher guanosine residue content upstream of the cleavage site (i.e. positions -4 to -2) were always cleaved more efficiently than wild-type substrate. This work shows that delta ribozyme constitutes a potential catalytic RNA for further gene-inactivation therapy.     

Characterization of ITO/ZnPc/CHR/In p-n junction-photovoltaic device using J–V, C–V and photoaction measurements

The electrical and photovoltaic properties of a newly designed two-layered photocell having the configuration ITO/ZnPc/CHR/In p-n junction were investigated. The rectification effect observed in the device is due to an energy barrier formed between the CHR and ZnPc layer. The depletion layer characteristics of the device were investigated by measuring the temperature variation of capacitance. These measurements indicate that a depletion layer of width 190 nm as well as potential barrier height of about 0.78 eV, decreases with temperature. The current–voltage characteristics of the device yield a barrier height of about 0.74 eV formed between ZnPc and CHR. The device showed a response to light over the whole visible region extending from 400 nm to 800 nm. The comparison of photoaction spectra with the absorption spectra also indicates the formation of an energy barrier between CHR and ZnPc. The dissociation of excitons induced by the built-in field potential existing between the CHR and ZnPc layers is responsible for photogeneration of the carriers. Various photovoltaic parameters were calculated and are discussed in detail.