KnowVolution of a Fungal Laccase toward Alkaline pH

To date, commercial laccase preparations are used in the food, textile, and paper and pulp industries (mild pH). Laccases are attractive in the synthesis of dye molecules or oxidative lignin treatment, which take place at high pH (≥8.0). So far, one fungal laccase has been reported to be active at alkaline pH. Herein, engineering of the fungal laccase from Melanocarpus albomyces (MaL) for increased activity toward the substrate 2,6-dimethoxyphenol at pH (≥9.0) is reported. Through a knowledge-gaining directed evolution (KnowVolution) campaign, the key positions Leu365 and Leu513 were identified to increase alkaline tolerance. Both positions are located in close proximity of the T1Cu site. Molecular docking and simulations studies reveal that both substitutions act in a synergic way to stabilize and improve laccase activity at higher pH. Kinetic characterization of the final variant MaL-M1 (L365E/L513M) revealed at pH 9.8 a threefold improved k_cat (k_cat=(6.0±0.2) s⁻¹) compared with that of wild-type M. albomyces laccase (k_cat=(2.11±0.07) s⁻¹).     

Photodegradation and biodegradation by bacteria of mulching films based on ethylene‐vinyl acetate copolymer: Effect of pro‐oxidant additives

The photodegradation (432 h under irradiation of Xe‐Lamp‐solar filter) of an ethylene vinyl acetate (EVA) copolymer with vinyl acetate content of 9% was studied, and the effect of iron and calcium stearates was evaluated using different techniques such us attenuated total reflectance‐Fourier transform infrared spectroscopy (ATR‐FTIR), gel permeation chromatography (GPC), and thermal analysis methods (DSC and TGA). A re‐arrangement in crystallization and consequent decrease in thermal stability were found through differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA), which were in agreement with the chain scission tendency. The presence of Ca and Fe pro‐oxidants additives in EVA films increased the ketone carbonyl formation and decreased the ester absorption band of the acetate respect to the pure EVA, as it was evidenced by the significant changes in Carbonyl Indexes found by FTIR. The activity of stearates has been also evaluated by chemiluminescence, where the temperature‐ramping tests under nitrogen showed the formation of a peroxide peak at lower temperature. The lower stability of the films containing pro‐oxidants was evidenced by the values of oxidation induction time (OIT) determined by DSC. The results were supported by GC‐MS, where the concentration of extracted products identified in the EVA containing pro‐oxidants was significant and a much greater decrease in molecular weight was determined by GPC, which confirmed the development of degradation for EVA with Ca and Fe stearates in comparison to pure EVA. Biodegradation of photodegraded EVA films were studied at 45°C during 90 days using a mixture of Bacillus (MIX) (B. cereus, B. megaterium, and B. subtilis) and, in parallel, by Brevibacillus borstelensis as reference strain. Biodegradation of EVA‐films was studied by Chemiluminescence, ATR‐FTIR and GC‐product analysis and the data confirm more efficient biodegradation on the materials containing pro‐oxidants. The chemiluminescence emissions due to decomposition of oxidation species was observed at lower temperatures on the biodegraded samples. Also, the drastic decrease of carbonyl index and the disappearance of photogenerated low molecular products with biodegradation were more efficient on the biodegraded films containing pro‐oxidants. EVA mineralization was evaluated by carbon dioxide measurement using indirect impedance technique. Biodegradation by B. borstelensis and MIX at 45°C was similar and exhibited a pronounced difference between the pure photodegraded EVA film (around 15% of mineralization) and the corresponding photodegraded films containing Ca and Fe stearates where biodegradation extent reached values of 23‐26% of biodegradation after 90 days. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Role of dense shelf water cascading in the transfer of organochlorine compounds to open marine waters

Settling particles were collected by an array of sediment trap moorings deployed along the Cap de Creus (CCC) and Lacaze-Duthiers (LDC) submarine canyons and on the adjacent southern open slope (SOS) between October 2005 and October 2006. This array collected particles during common settling processes and particles transferred to deep waters by dense shelf water cascading (DSWC). Polychlorobiphenyls (PCBs), dichlorodiphenyltrichloroethane and its metabolites (DDTs), chlorobenzenes (CBzs)--pentachlorobenzene and hexachlorobenzene--and hexachlorocyclohexanes were analyzed in all samples. The results show much higher settling fluxes of these compounds during DSWC than during common sedimentation processes. The area of highest deposition was located between 1000 and 1500 m depth and extended along the canyons and outside them showing their channelling effects but also overflows of dense shelf water from these canyons. Higher fluxes were observed near the bottom (30 m above bottom; mab) than at intermediate waters (500 mab) which is consistent with the formation and sinking of dense water close to the continental shelf and main displacement through the slope by the bottom. DSWC involved the highest settling fluxes of these compounds ever described in marine continental slopes and pelagic areas, e.g., peak values of PCBs (960 ng · m(-2) · d(-1)), DDTs (2900 ng · m(-2) · d(-1)), CBzs (340 ng · m(-2) · d(-1)) and lindane (180 ng · m(-2) · d(-1)).     

Dynamic mechanical properties and morphology of poly(benzyl methacrylate)/epoxy thermoset blends

Poly(benzyl methacrylate) (PBzMA)/epoxy thermoset blends of composition 5 to 25 wt% of PBzMA were prepared curing with 4,4′diaminodiphenylmethane (DDM), to study the influence of composition on the morphology and dynamic‐mechanical properties of the blends. The cured blends are phase separated in PBzMA‐rich phase and epoxy rich‐phase. As the PBzMA content increases, the morphology evolves from nodular, to combined and to totally inverted. The analysis of the α‐mechanical relaxations indicates that the glass transition temperatures (T_g) of PBzMA and of epoxy in the blends are different from the neat polymers, this is related to a noncomplete phase separation on curing. The profiles of the loss modulus‐temperature curves are correlated with the change in morphology that appears increasing the PBzMA content. The storage modulus‐temperature curves are highly dependent on the morphology of the samples. The storage modulus‐composition dependence is predicted using several models for two phase composites. POLYM. ENG. SCI., 50:1820–1830, 2010. © 2010 Society of Plastics Engineers     

Vulcanization of EPDM rubber compounds with and without blowing agents: Identification of reaction events and TTT‐diagram using DSC data

Vulcanization of industrial‐like ethylene propylene diene termonomer rubber compound is studied using a differential scanning calorimetry (DSC). The analysis starts with DSC information to obtain the total transformation heat, followed by an isothermal‐dynamic temperature ramp that captures diffusion‐controlled reaction kinetics. The vulcanization is modeled by an auto‐catalytic Kamal–Sourour model, complemented with a Kissinger model for the prediction of one energy of activation, DiBenedetto's equation for the glass transition temperature, and adjusted reaction constants to include diffusion mechanisms. Two rubber formulations, with and without blowing agents, containing crosslinking agents, primary and secondary accelerators, activators, promoters, and processing aids are studied. The identification and separation of multiple reaction events, occurring during crosslinking of the compound without a blowing agent, is done through a 2^k design of experiments. Time–temperature–transformation (TTT) diagrams are calculated, integrating the kinetic model, thereby delineating processability windows, providing avenues for optimization, design, and online processing control. According to the kinetics and the TTT diagrams, the blowing agent induces several differences to the vulcanization reaction: decreases reaction temperatures while increasing reaction heats. It eliminates the exothermic peak before vulcanization and decreases the fully cured resin's glass transition temperature. Therefore, the presence of the blowing agent drives a shift in the vitrification line, resulting in a reduced operational window. POLYM. ENG. SCI., 55:2073–2088, 2015. © 2014 Society of Plastics Engineers     

Thrombotic thrombopenic purpura and HIV infection. Apropos of a case

In the past years, more than thirty cases of thrombotic thrombocytopenic purpura (TTP) had been described associated to infection by the human immunodeficiency virus. Some authors have suggested the presence of a causal relationship between both entities, although the common nexus is still unknown. It usually has a fulminant onset, affecting all the risk groups and in any stage of the disease. The clinical manifestations are similar to the classical forms, as well as the evolution and response to treatment. We present a new clinical case, typical in its presentation and its good response to treatment with plasmatic spares associated to PFC and steroid infusion. We believe that the presence of clinical signs suggesting TTP in a patient would necessarily discard the presence of HIV infection and, the other way round, the presence of clinical signs suggesting TTP in a patient with HIV infection would determine the onset of an early and aggressive treatment based on plasmatic spares, given that the prognosis is linked to an early onset of the treatment.     

COMPARING PRONOUN RESOLUTION ALGORITHMS

This paper discusses the comparative evaluation of five well-known pronoun resolution algorithms conducted with the help of a purpose-built tool for consistent evaluation in anaphora resolution, termed the evaluation workbench. The workbench enables the evaluation and comparison of pronoun resolution algorithms on the basis of the same preprocessing tools and test data. The tool is controlled by the user who can conduct the evaluation according to a variety of parameters, with regard to the types of anaphors and the samples used for evaluation. The extensive comparative evaluation of the pronoun resolution algorithms showed that their performance was significantly lower than the figures reported in the original papers describing the algorithms. The evaluation study concluded that the main reason for this drop in performance is the fact that all algorithms operate in a fully automatic mode.     

Photochemistry and photopolymerization activity of perester derivatives of benzophenone

The spectroscopic properties and photopolymerization activities of a mono- and tetraperester derivative of benzophenone are examined and compared with those of benzophenone. Their photopolymerization activity in methyl methacrylate (MMA) and an ethoxylated bis-phenol-A diacrylate have been studied using a combination of gel permeation chromatography (GPC), and real time Fourier transform infrared spectroscopy (RTFTIR) as well as the commercial pendulum hardness test. Using GPC analysis on the poly(methyl methacrylate) samples the tetra--t-butyl perester derivative of benzophenone is found to give a higher weight average (M_w) and number average (M_n) molecular weight polymer than that produced using the mono perester. For the two peresters of benzophenone photopolymerization efficiency using real time FTIR increases with increasing initiator concentration, and no self-termination is observed up to 0.75% w/w concentration with the mono perester derivative being the more efficient initiator. Similar results were obtained using the commercial pendulum hardness tester with a triacrylate/epoxyurethane acrylate resin with benzophenone exhibiting the lowest activity. Photopolymerization activities of the initiators correlate well with their spectroscopic properties. The phosphorescence quantum yield is higher for the monoperester than the tetraperester derivative and is consistent with a shorter lifetime and lower photolysis quantum yields in 2-propanol. Compared with benzophenone, phosphorescence analysis indicates that the perester groups impart a degree of charge-transfer content to the molecule which is consistent with the degree of substitution. Ketyl radical formation on microsecond flash photolysis follows the order benzophenone > mono- > tetraperester derivative and is consistent with the phosphorescence quantum yields. On nanosecond laser flash photolysis in nitrogen-saturated acetonitrile, triplettriplet absorption is extremely weak for both the perester derivatives, being stronger for the monoperester.     

Patent families: When do different definitions really matter?

Data on patent families is used in economic and statistical studies for many purposes, including the analysis of patenting strategies of applicants, the monitoring of the globalization of inventions and the comparison of the inventive performance and stock of technological knowledge of different countries. Most of these studies take family data as given, as a sort of black box, without going into the details of their underlying methodologies and patent linkages. However, different definitions of patent families may lead to different results. One of the purposes of this paper is to compare the most commonly used definitions of patent families and identify factors causing differences in family outcomes. Another objective is to shed light into the internal structure of patent families and see how it affects patent family outcomes based on different definitions. An automated characterization of the internal structures of all extended families with earliest priorities in the 1990s, as recorded in PATSTAT, found that family counts are not affected by the choice of patent family definitions in 75% of families. However, different definitions may really matter for the 25% of families with complex structures and lead to different family compositions, which might have an impact, for instance, on econometric studies using family size as a proxy of patent value.     

The multifinality constraints effect: How goal multiplicity narrows the means set to a focal end.

In the presence of several objectives, goal conflict may be avoided via multifinal means, which advance all of the active goals at once. Because such means observe multiple constraints, they are fewer in number than the unconstrained means to a single goal. Five experimental studies investigated the process of choosing or generating such means for multiple goals. We found that the simultaneous activation of multiple goals restricted the set of acceptable means to ones that benefitted (or at least, did not harm) the entire set of active goals. Two moderators of this phenomenon were identified: (a) the feasibility of identifying multifinal means, which was dependent on the relations between the different active goals, and (b) the enhanced importance of the focal goal, which resulted in the inhibition of its alternatives and the consequent relaxation of multifinality constraints. (PsycINFO Database Record (c) 2011 APA, all rights reserved)