Cellulose Aerogel Fibers Tested on a REXUS 18 Rocket – The ACTOR Project

Aerogels are high‐performance materials used for space and aviation purposes. Cellulose aerogel fibers have been investigated under real space conditions for their insulation properties. The experiments were carried out in a one‐stage high‐altitude research rocket of the improved ORION type. A cuboid module with measurement cells, camera modules, and electronic devices has been developed for monitoring the insulation behavior of cellulose aerogel non‐woven samples. The thermal behavior of these samples has been analyzed and compared to cellulose cloth (cotton) and aluminum for reference.     

The impact of polypropylene‐graft‐maleic anhydride on the crystallization and dynamic mechanical properties of isotactic polypropylene

Differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA) were used to identify the mechanisms that lead to differences in the mechanical behavior of formulations of polypropylene blended with maleated polypropylene (MAPP) copolymers. MAPP lowered the melting temperature of PP indicating that less stable crystals were formed possibly because of cocrystallization of PP and MAPP. Crystallization kinetics revealed that copolymers do not change the rate of crystal growth, but may retard nucleation leading to a more spherulitic morphology. The dynamic storage modulus slightly increased in the glassy region with the small addition amounts of MAPP, while mechanical dampening systematically decreased with MAPP addition. An analysis of the viscoelastic behavior did not reveal any real differences in molecular coupling around the β‐transition of PP with the addition of the MAPP copolymer. At low addition levels, MAPP does not appear to have a significant impact on the viscoelastic properties of the polymer blend. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Recycling carbon fiber composites using microwave irradiation: Reinforcement study of the recycled fiber in new composites

With increasing use of carbon fiber reinforced polymer (CFRP) composites in transportation, sports, and many other industries, recycling of the scrap and end‐of‐life composites has presented both great challenges and opportunities. In this work, we report our study on reclaiming carbon fibers from CFRP using energy efficient microwave irradiation. Different irradiation conditions were used and the optimal conditions were determined based on the surface morphology of the recycled fiber. Polypropylene (PP) and Nylon, representing nonpolar and polar polymers, respectively, were reinforced using the recycled fiber through extrusion and injection molding. For comparison, PP and Nylon reinforced by virgin carbon fiber were also prepared using the same processing conditions. Tensile, flexural, and impact test results showed that, while both carbon fibers could improve these properties, they exhibited different reinforcing effects on the two polymers. The recycled fiber outperformed the virgin fiber in reinforcing PP whereas the virgin fiber performed better in Nylon. This was due to the differences in surface roughness, surface bonding, and fiber aspect ratio between the two fibers. This study shows the great potential of recycled carbon fiber and microwave irradiation as an effective recycling technique. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42658.     

Transformation of Free and Dipeptide‐Bound Glycated Amino Acids by Two Strains of Saccharomyces cerevisiae

The yeast Saccharomyces cerevisiae transforms branched‐chain and aromatic amino acids into higher alcohols in the Ehrlich pathway. During microbiological culturing and industrial fermentations, this yeast is confronted with amino acids modified by reducing sugars in the Maillard reaction (glycation). In order to gain some preliminary insight into the physiological “handling” of glycated amino acids by yeasts, individual Maillard reaction products (MRPs: fructosyllysine, carboxymethyllysine, pyrraline, formyline, maltosine, methylglyoxal‐derived hydroimidazolone) were administered to two strains of S. cerevisiae in a rich medium. Only formyline was converted into the corresponding α‐hydroxy acid, to a small extent (10 %). Dipeptide‐bound pyrraline and maltosine were removed from the medium with concomitant emergence of several metabolites. Pyrraline was mainly converted into the corresponding Ehrlich alcohol (20–60 %) and maltosine into the corresponding α‐hydroxy acid (40–60 %). Five specific metabolites of glycated amino acids were synthesized and characterized. We show for the first time that S. cerevisiae can use glycated amino acids as a nitrogen source and transform them into new metabolites, provided that the substances can be transported across the cell membrane.     

A Boronic Acid Assay for the Detection of Mucin‐1 Glycoprotein from Cancer Cells

Cell surface glycoproteins are commonly aberrant in disease and act as biomarkers that facilitate diagnostics. Mucin‐1 (MUC1) is a prominent example, exhibiting truncated glycosylation in cancer. We present herein a boronic acid microplate assay for sensitive and high‐throughput detection of such glycoproteins. The immobilization of biotin–boronic acid 1 onto streptavidin plates generated a multivalent surface for glycoprotein recruitment and detection. We first validated the binding properties of 1 in solution through titrations with alizarin dye. Next, the microplate assay was explored through horseradish peroxidase (HRP) analysis as a proof‐of‐concept glycoprotein with chemiluminescence detection. Finally, this platform was applied for the detection of MUC1 directly from MCF‐7 human breast cancer cell lysates by using an HRP‐tagged antibody that targets the cancerous form of this glycoprotein. Sensitive, dose‐dependent detection of MUC1 was observed, showcasing the efficacy of this platform for detecting disease‐associated glycoproteins.     

Cold sintering process: A new era for ceramic packaging and microwave device development

Cold sintering process (CSP) is an extremely low‐temperature sintering process (room temperature to ~200°C) that uses aqueous‐based solutions as transient solvents to aid densification by a nonequilibrium dissolution‐precipitation process. In this work, CSP is introduced to fabricate microwave and packaging dielectric substrates, including ceramics (bulk monolithic substrates and multilayers) and ceramic‐polymer composites. Some dielectric materials, namely Li₂MoO₄, Na₂Mo₂O₇, K₂Mo₂O₇, and (LiBi)_0.5MoO₄ ceramics, and also (1?x)Li₂MoO₄?xPTFE and (1?x)(LiBi)_0.5MoO₄?xPTFE composites, are selected to demonstrate the feasibility of CSP in microwave and packaging substrate applications. Selected dielectric ceramics and composites with high densities (88%‐95%) and good microwave dielectric properties (permittivity, 5.6‐37.1; Q × f, 1700‐30 500 GHz) were obtained by CSP at 120°C. CSP can be also used to potentially develop a new co‐fired ceramic technology, namely CSCC. Li₂MoO₄?Ag multilayer co‐fired ceramic structures were successfully fabricated without obvious delamination, warping, or interdiffusion. Numerous materials with different dielectric properties can be densified by CSP, indicating that CSP provides a simple, effective, and energy‐saving strategy for the ceramic packaging and microwave device development.     

Measurement and modeling of lignin pyrolysis

Pyrolysis of lignin is one approach that has been investigated to upgrade this material into higher value products. However, there have been relatively few efforts to quantitatively model these reactions. This paper describes a methodology for modeling lignin pyrolysis which has been extensively developed for related materials like coal. The samples are characterized using pyrolysis experiments under a standard set of conditions, where the products are analyzed by Fourier Transform Infrared (FT-IR) Spectroscopy and Field Ionization Mass Spectrometry (FIMS). Solvent extraction experiments are done to determine the extractables yields and elemental analysis is done to further constrain the model.

One lignin, produced from ethanol/water extraction of mixed hardwoods, was selected for the application of this modeling approach. The model was able to qualitatively predict the tar molecular weight distributions and quantitatively predict the variations of the gas and tar evolution rates and yields with heating rate for the calibration set of experiments. The model can be improved by more precise information on lignin structure, crosslinking chemistry, and tar transport mechanisms. It also needs to be validated by simulation of pyrolysis conditions at high heating rates and/or high pressures for which data is currently not available.     

Evidence for mineral matter forms in coal liquefaction extracts

High- and low-temperature ashes from feed coal, coal extract solution and filter cake from a two-stage coal liquefaction process have been studied by X-ray diffraction (XRD) and scanning electron microscopy/energy dispersive X-ray fluorescence (SEM/EDX). Hydrocracking experiments using alumina support only, in place of the active Ni/Mo catalyst on alumina, were also carried out, with trace metal analysis of the coal extract solution feed and hydrocracked extracts using atomic absorption and emission spectroscopy. The major mineral transformations occurring were of pyrite to pyrrhotite and the fixation of organic sulphur by calcium carbonate. Mineral particles were not observed in the coal extract solution ashes, even under high magnification, and the study indicated that size alone was not a determining factor as to whether a coal mineral was to be found in a coal-derived liquid. None of the trace metals was deposited on the alumina support under hydrocracking conditions, in marked contrast to the results obtained with the normal Ni/Mo catalyst. These results lead to the conclusion that for the deposition of trace elements to occur a reaction must take place and hence the trace elements must be chemically bound in some form.     

Mathematical modelling of silica deposition in Tongonan-I reinjection wells, Philippines

Mathematical models of silica deposition are derived using the method of characteristics for the problem of variable rate injection into a well producing radially symmetric flow. Solutions are developed using the first order rate equation of silica deposition suggested by Rimstidt and Barnes (1980). The changes in porosity and permeability resulting from deposition are included in the models. The models developed are successfully applied in simulating the changes in injection capacity in some of the reinjection wells in Tongonan geothermal field, Philippines.     

Dominant Mechanisms that Shape the Airborne Particle Size and Composition Distribution in Central California

The size and composition of ambient airborne particulate matter is reported for winter conditions at five locations in (or near) the San Joaquin Valley in central California. Two distinct types of airborne particles were identified based on diurnal patterns and size distribution similarity: hygroscopic sulfate/ammonium/nitrate particles and less hygroscopic particles composed of mostly organic carbon with smaller amounts of elemental carbon. Daytime PM₁₀ concentrations for sulfate/ammonium/nitrate particles were measured to be 10.1 μ g m^?3, 28.3 μ g m^?3, and 52.8 μ g m^?3 at Sacramento, Modesto and Bakersfield, California, respectively. Nighttime concentrations were 10–30% lower, suggesting that these particles are dominated by secondary production. Simulation of the data with a box model suggests that these particles were formed by the condensation of ammonia and nitric acid onto background or primary sulfate particles. These hygroscopic particles had a mass distribution peak in the accumulation mode (0.56–1.0 μ m) at all times. Daytime PM₁₀ carbon particle concentrations were measured to be 9.5 μ g m^?3, 15.1 μ g m^?3, and 16.2 μ g m^?3 at Sacramento, Modesto, and Bakersfield, respectively. Corresponding nighttime concentrations were 200–300% higher, suggesting that these particles are dominated by primary emissions. The peak in the carbon particle mass distribution varied between 0.2–1.0 μ m. Carbon particles emitted directly from combustion sources typically have a mass distribution peak diameter between 0.1–0.32 μ m. Box model calculations suggest that the formation of secondary organic aerosol is negligible under cool winter conditions, and that the observed shift in the carbon particle mass distribution results from coagulation in the heavily polluted concentrations experienced during the current study. The analysis suggests that carbon particles and sulfate/ammonium/nitrate particles exist separately in the atmosphere of the San Joaquin Valley until coagulation mixes them in the accumulation mode.