Polyfunctional macromonomers obtained from 2,2‐bis(hydroxymethyl) propanoic acid and tall oil fatty acids

Macromonomers (MMs) were obtained with different proportions of dimethylolpropionic acid (DMPA) and tall oil fatty acid (TOFA). The MMs were characterized by their acid value (AV), their hydroxyl value (OHV), IR spectroscopy, NMR, electrospray ionization–mass spectrometry, UV spectroscopy, rheological, differential scanning calorimetry, thermogravimetric analysis, gloss, flexibility, and adherence analyses. The presence of hydroxyl and ester groups and double bonds were confirmed by IR and NMR analyses. IR analysis showed that the intensity of the OH groups decreased with the addition of TOFA. In all cases, the AVs of the MMs were lower than those of DMPA and TOFA. By electrospray ionization–mass spectrometry, the formation of the DMPA homopolymers and structures with molecular weights higher than that of DMPA were observed. All of the MMs were amorphous. The viscosity of the MMs decreased with the addition of TOFA. The gloss values of the MMs at 85° were higher than 100, and the flexibility was good. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42029.     

Respiration studies of penicillin solid-state fermentation

An earlier work showed that when the bagasse content (BC) of the solid medium was decreased within a wide range of values, penicillin production by solid-state fermentation was always increased. Respiration studies were performed to understand how BC controls the secondary metabolism in this culture system. CO2 production of solid cultures with different compositions was monitored. In cultures of series A, the initial moisture content was increased and this variation was compensated by decreasing the nutrient and BC of the medium. In series B the initial moisture content was increased while BC was decreased and the nutrient content increased. In addition, penicillin production and respiration was also studied in extreme media (dry and concentrated and humid and diluted), with high and low BC. Criteria for the interpretation of respiration kinetics of the idiophase were established for the first time in this work. For the cumulative form (total CO2/g dry matter vs t) as well as for derivative (CO2/g dm/h vs t) respiration kinetics, the CO2 production rate (Q(CO2)) was determined by calculating the slope of the cumulative curve. Results indicate that Q(CO2) of the tropho- and idiophases was directly related to the BC of the solid medium (and inversely related to penicillin yields). These conclusions were confirmed by analysis of the derivative form, the results of which indicate that a lower but stable metabolic activity is essential for obtaining high penicillin yields in solid-state fermentation (SSF). The results indicate that the derivative CO2 production kinetics proved to be a more precise and sensitive indicator of the culture metabolic activity during idiophase than the cumulative respiration kinetics.     

Mutants of Streptomyces cattleya defective in the synthesis of a factor required for thienamycin production

Thienamycin non-producing mutants of Streptomydes cattleya were identified that displayed a cross-feeding relationship. A diffusible product from one of these mutants (RK-11) resulted in restoration of thienamycin production when fed to cultures of another mutant (RK-4). In vivo radiolabeling experiments were conducted to test whether the RK-11 mutant produced a late biosynthetic intermediate which contained a carbapenem ring and a cysteaminyl and/or a hydroxyethyl side chain. Both [35S]cystine and [methyl-3H]methionine were used to label the RK-11 product which was then fed to RK-4 cultures. None of the thienamycin subsequently produced by RK-4 converter cells was labeled, implying the lack of either side chain of the thienamycin molecule in the RK-11 product. Further stability studies suggested that the RK-11 product does not contain a carbapenem ring. Additional feeding experiments with RK-4 cells also ruled out the possibility that the RK-11 product is a co-factor necessary for thienamycin production. It is concluded that the RK-11 product may regulate expression of the thienamycin gene cluster.     

Biochemical mechanism of the effect of barbital on rifamycin B biosynthesis by Amycolatopsis mediterranei (M18 strain)

It is well known that 5,5-diethylbarbituric acid (barbital) in the culture medium can stimulate the production of rifamycin B by Amycolatopsis mediterranei, particularly in industrial processes. However, the mechanism by which barbital exerts this effect is unknown. Results in this work show that the barbital effect is only evident under low aeration conditions (50-ml microfermentors with 7 ml of medium, 0.08 l/h air flow). Under these conditions, cultures with barbital showed similar CO2 production (in relation to a control without barbital), but higher oxygen uptake indicated that the extra O2 consumed was used in the increased rifamycin biosynthesis. Moreover, using a resting cell system where no antibiotic is produced, it was possible to show that barbital inhibits the respiratory chain, since O2 uptake decreased by 30%. Finally, we present biochemical results that suggest that a cytochrome P450-type monoxygenase, which can use atmospheric oxygen, is induced by barbital in an industrial-type strain of A. mediterranei.     

Influence of annealing on the critical temperature of Bi–Pb–Sr–Ca–Cu–O thin films

Superconducting Bi–Pb–Sr–Ca–Cu–O (BPSCCO) thin films were grown on MgO substrates by a spray pyrolysis technique, followed by a solid-state reaction. The thin films with nominal composition Bi_1.65Pb_0.4Sr_1.2Ca_1.2Cu_2.5(NO₃)_δ were grown varying mainly the annealing temperature between 835 and 855 °C in order to observe the influence on the critical temperature T_c. At 855 °C the higher T_c was obtained for the 2212 phase. The thin films were then analyzed by X-ray diffraction, R-T measurements and atomic absorption spectroscopy.     

Biomass energy from wood chips: Diesel fuel dependence?

Most renewable energy sources depend to some extent on use of other, non-renewable sources. In this study we explore use of diesel fuel in producing and transporting woody biomass in the state of New Hampshire, USA. We use two methods to estimate the diesel fuel used in woody biomass production: 1) a calculation based on case studies of diesel consumption in different parts of the wood chip supply chain, and 2) to support extrapolating those results to a regional system, an econometric study of the variation of wood-chip prices with respect to diesel fuel prices. The econometric study relies on an assumption of fixed demand, then assesses variables impacting supply, with a focus on how the price of diesel fuel affects price of biomass supplied. The two methods yield similar results. The econometric study, representing overall regional practices, suggests that a $1.00 per liter increase in diesel fuel price is associated with a $5.59 per Mg increase in the price of wood chips. On an energy basis, the diesel fuel used directly in wood chip production and transportation appears to account for less than 2% of the potential energy in the wood chips. Thus, the dependence of woody biomass energy production on diesel fuel does not appear to be extreme.     

The Co-Au interface in bimetallic nanoparticles: a high resolution STEM study

We report the formation of Au/Co nanoparticles and their characterization by aberration (Cs) corrected scanning transmission electron microscopy (STEM). The nanoparticles were synthesized by inert gas condensation, forming initially core-shell and bimetallic crystals. However, after thermal treatment at normal atmospheric conditions, the Co nanoparticles changed their morphology into a fine layer forming a perfect interface with the gold. The ordering of the zone rich in Co presents a fcc arrangement matching the gold lattice. The atomic analysis on the interface and the comparison of the STEM images with numerical simulations corroborated the atomic substitution of gold by cobalt.