The stability of blends of incompatible thermoplastics

Conventional thermodynamic reasoning would predict that it would be very difficult to melt blend incompatible polymers and that if such blends were made they would be highly unstable and would phase separate upon heating. A method has been developed to melt blend incompatible polymers (such as poly(methylmethacrylate) and polyethylene) to form two continuous interpenetrating phases and that upon prolonged heating the stability of the structure is increased rather than decreased.     

The Evolution of Dextrins During the Mashing and Fermentation of All‐malt Whisky Production

The production of malt whisky involves the mashing of barley malt, followed by the fermentation of the resulting wort without further treatment. While this process has many parallels to the production of an all‐malt beer, one of the main differentiating steps during substrate preparation is the inclusion of a boiling step for the wort in the production of beer. Other than the destructive action of the boiling process on microorganisms, the boiling also destroys all malt enzyme activity. Since a typical whisky wash is not boiled it carries through a certain proportion of microbial activity associated with the malt, but more importantly it retains some enzyme activity that has been activated during the malting and mashing processes. The changes in sugars and dextrins during both mashing and fermentation of the resulting wash were investigated. Evidence of the continuous amylolytic activity during an unboiled, all‐malt wash fermentation is shown; while no ongoing amylolytic activity could be deduced during the fermentation of a boiled all‐malt wort. Furthermore, the data suggests that the amylolytic activity during mashing and fermentation are different with regards to α‐amylase action linked to its multiple‐attack action pattern as a function of substrate conformation, temperature, and effectiveness of potential hydrolytic events.     

Electrospray deposition of in-situ UV-photoactivated polyimide films

In electrospray deposition, a precursor solution, composed of a solute material in a volatile carrier solvent, is atomized into a spray of charged microdroplets under the influence of a strong electric field. As the droplets are in-flight, the carrier solvent evaporates, leaving behind the solute material that can be delivered to a target surface to create a film. In this work, we employ electrospray deposition to create films of UV-photosensitive polyimide. Films were deposited using in-situ UV exposure, where the in-flight droplets and deposited material were exposed to UV during deposition. The characteristics of these films were compared to films exposed to UV only after deposition (referred to as post-UV exposure). The microstructure of the deposited films was notably different for the two exposure modes, in which the in-situ UV exposed films have a wavy/dimpled surface, compared to the flat and smooth surface of the post-UV exposed films. However, thermogravimetric analysis and Fourier transform infrared spectroscopy showed that the UV activation of the in-situ UV and post-UV exposed films was nearly identical. Breakdown testing was conducted to evaluate the dielectric strength of the films. Overall, the in-situ UV and post-UV exposed films exhibited similar breakdown strengths of approx. 430–450 V/μm. The use of in-situ UV exposure cuts in half the processing time for producing thin polyimide films.     

Amorphization of α-quartz and comparative study of defects in amorphized quartz and Si nanocrystals embedded in amorphous silica

Ion irradiation of α-quartz renders the crystal SiO₂ structure amorphous. The enormous amount of structural defects produced after ion irradiation give a chance for photoactive intrinsic defects to be formed. These may be responsible for the photoluminescence in irradiated α-quartz. On the other hand, the radiation defects are not stable, and thus, an alternative structure where the defects of interest can be stabilized is required. The stabilization of the defects can be achieved in the structures of amorphous silica with embedded Si nanocrystals (NC), thanks to the unique structure of the formed interface. By means of Molecular Dynamics (MD), we analyze defects in both amorphized α-quartz and Si-NC/a-SiO₂ interfaces formed by 1.1, 2.4 and 4 nm diameter NC’s. In the simulation, we employ a classical interatomic potential and a potential, which takes into consideration a charge transfer between Si and O atoms. We show that although the number of silanone bonds SiO in irradiated quartz is higher, they are also found in a Si-NC/a-SiO₂ interface without the necessity of preceding irradiation of the sample. We also compare the defects in irradiation-amorphized quartz and the three sizes of Si-NC/a-SiO₂ interfaces. Analysis of the charges showed that the charge state of coordination defects depends on the type of atoms in the near neighborhood.     

Over-Expression of Catalase in Myeloid Cells Confers Acute Protection Following Myocardial Infarction

Cardiovascular disease is the leading cause of death in the United States and new treatment options are greatly needed. Oxidative stress is increased following myocardial infarction and levels of antioxidants decrease, causing imbalance that leads to dysfunction. Therapy involving catalase, the endogenous scavenger of hydrogen peroxide (H₂O₂), has been met with mixed results. When over-expressed in cardiomyocytes from birth, catalase improves function following injury. When expressed in the same cells in an inducible manner, catalase showed a time-dependent response with no acute benefit, but a chronic benefit due to altered remodeling. In myeloid cells, catalase over-expression reduced angiogenesis during hindlimb ischemia and prevented monocyte migration. In the present study, due to the large inflammatory response following infarction, we examined myeloid-specific catalase over-expression on post-infarct healing. We found a significant increase in catalase levels following infarction that led to a decrease in H₂O₂ levels, leading to improved acute function. This increase in function could be attributed to reduced infarct size and improved angiogenesis. Despite these initial improvements, there was no improvement in chronic function, likely due to increased fibrosis. These data combined with what has been previously shown underscore the need for temporal, cell-specific catalase delivery as a potential therapeutic option.