A dimensional reduction approach to modulate the core ruminal microbiome associated with methane emissions via selective breeding

The rumen is a complex microbial system of substantial importance in terms of greenhouse gas emissions and feed efficiency. This study proposes combining metagenomic and host genomic data for selective breeding of the cow hologenome toward reduced methane emissions. We analyzed nanopore long reads from the rumen metagenome of 437 Holstein cows from 14 commercial herds in 4 northern regions in Spain. After filtering, data were treated as compositional. The large complexity of the rumen microbiota was aggregated, through principal component analysis (PCA), into few principal components (PC) that were used as proxies of the core metagenome. The PCA allowed us to condense the huge and fuzzy taxonomical and functional information from the metagenome into a few PC. Bivariate animal models were applied using these PC and methane production as phenotypes. The variability condensed in these PC is controlled by the cow genome, with heritability estimates for the first PC of ~0.30 at all taxonomic levels, with a large probability (>83%) of the posterior distribution being >0.20 and with the 95% highest posterior density interval (95%HPD) not containing zero. Most genetic correlation estimates between PC1 and methane were large (≥0.70), with most of the posterior distribution (>82%) being >0.50 and with its 95%HPD not containing zero. Enteric methane production was positively associated with relative abundance of eukaryotes (protozoa and fungi) through the first component of the PCA at phylum, class, order, family, and genus. Nanopore long reads allowed the characterization of the core rumen metagenome using whole-metagenome sequencing, and the purposed aggregated variables could be used in animal breeding programs to reduce methane emissions in future generations.     

A Symmetrical Diester as the Sex Attractant Pheromone of the North American Click Beetle Parallelostethus attenuatus (Say) (Coleoptera: Elateridae)

Hexanoic acid, 1-octanol, 1,8-octanediol, octyl hexanoate, 1,8-octanediol monohexanoate, and 1,8-octanediol dihexanoate were identified in headspace volatiles collected from the crushed abdomen of a female click beetle of the species Parallelostethus attenuatus (Say) (Elaterinae, tribe Elaterini). In field trials carried out in Illinois, South Carolina, North Carolina, and Virginia, adult male beetles were strongly attracted to 1,8-octanediol dihexanoate alone. Blends of the dihexanoate with one or more of the other compounds proved to be less attractive than the dihexanoate alone, suggesting that the pheromone of this species may consist of a single compound. The symmetrical diester structure of the pheromone is a novel natural product and appears to be structurally unique among insect pheromones.

     

Progress in the design of zeolite catalysts for biomass conversion into biofuels and bio-based chemicals

This article reviews the recent advances in the development of zeolite catalysts for biomass valorization processes to produce both biofuels and/or bio-based chemicals, which is an emerging and fast expanding field. The work deals with different types of feedstocks, including vegetable oils, lignocellulose and sugars, as well as with a number of relevant intermediates and platform molecules. Transformation of biomass into valuable products is hindered by a number of factors, mainly related to its complex composition, as biomass typically consists of bulky molecules with high oxygen content. Accordingly, biomass processing usually requires the combination of multiple steps and severe conditions, hence concepts like atom efficiency, product selectivity, and catalyst deactivation become of special relevance. A great progress has been achieved in the past years engineering the properties of zeolites for being adapted to the challenges associated to biomass valorization. The possibility of tailoring the main physicochemical properties of zeolites has become now a reality, being the major reason that explains the success achieved by this class of materials in a growing variety of biomass conversion pathways, as those described in this work: catalytic cracking and pyrolysis, hydrotreatments, with special relevance for hydrodeoxygenation processes, as well as in a high number of condensation, isomerization, and dehydration reactions. Thus, the development of hierarchical zeolites, exhibiting enhanced accessibility, and the possibility of introducing and combining in a controlled way different types of active sites (Brønsted and Lewis acid centers, basic sites, and metal phases) are the main basis of the excellent performance of zeolites in numerous biomass conversion routes.     

Removal of persistent pharmaceutical micropollutants from sewage by addition of PAC in a sequential membrane bioreactor

The performance of a membrane bioreactor operating in a sequential mode (SMBR) using an external flat-plate membrane was investigated. After 200 days of operation, a single addition of 1 g L⁻¹ Powdered Activated Carbon (PAC) was added directly into the mixed liquor in order to enhance the simultaneous removal of nutrients and pharmaceutical micropollutants from synthetic urban wastewater. Throughout the entire operation (288 days), Chemical Oxygen Demand (COD) removal efficiencies were up to 95%, ammonium nitrogen removal was maintained over 70-80%, whereas phosphorus removal achieved only high values (around 80%) after PAC addition. During the operation of the SMBR without PAC addition, micropollutants which exerted a more recalcitrant behaviour were carbamazepine, diazepam, diclofenac and trimethoprim, with no significant removal. On the other hand, moderate removals (42-64%) were observed for naproxen and erythromycin, whereas ibuprofen, roxithromycin and fluoxetine were removed in the range of 71-97%. The addition of PAC into the aeration tank was a successful tool to improve the removal of the more recalcitrant compounds up to 85%. The highest removal with PAC was observed for carbamazepine, trimethoprim as well as for roxithromycin, erythromycin and fluoxetine. The latter four compounds have amine groups and pKa in the range 6.7-10.1, thus the interaction between PAC and the positively charged amino groups might be the cause of their comparatively better results. Microbial ecology present in the biomass showed a higher abundance of Accumulibacter phosphatis as well as the ammonium oxidizing bacteria belonging to the genus Nitrosomonas after PAC addition.     

Betons a hautes performances,a granulats artificiels actifs

High strength concretes, in particular at early ages (more than 40 MPa at 3 days and up to 80 MPa at 7 days), are obtained by replacement of certain granular size ranges of sand or gravel by cement-active artificial aggregates in a given concrete composition elaborated with a local supply of aggregates and cement. The strengthening of the paste-aggregate bond by chemical reactions between the artificial aggregates and the cement also involves an improvement of other concrete performances and not only of mechanical strengths. The cracking ability is decreased, the wear strength is higher, and water permeability is low or even nil for certain compositions. The laboratory results are confirmed by tests on the site and show the possibility of achieving high strength concretes without any particular selection of cement and natural aggregates.     

Entrepreneurial quality and regional development: Characterizing SME sectors in low income areas*

This paper analyses the characteristics of SMEs in less‐developed areas in comparison with more advanced economies. The conceptual framework includes different factors making up the so‐called ‘entrepreneurial quality’ of the SME sector: the personal characteristics of the entrepreneurs (motivations and previous experience), different dimensions of the SMEs’ entrepreneurial orientation, and the patterns of the SMEs’ insertion in national and global value chains. The empirical analysis uses data of SMEs in four different Spanish provinces representing examples of low income economies and comparatively high income ones, respectively. Results show the SMEs in the low income economies to be characterized by a lower entrepreneurial quality.     

Synthesis and characterization of poly (styrene‐b‐[(butadiene)1−x‐(ethylene‐co‐butylene)x] ‐b‐styrene) star‐like molecular polymers produced by partial hydrogenation of SBS

This article reports the synthesis and characterization of four arm star‐shaped poly(styrene‐b‐[(butadiene)_1?x‐(ethylene‐co‐butylene)_x]‐b‐styrene) (SBEBS) copolymers. A series of SBEBS copolymers with different compositions of the elastomeric block were produced by hydrogenating a given poly(styrene‐b‐butadiene‐b‐styrene) (SBS) copolymer using a catalyst prepared from bis(η⁵‐cyclopentadienyl)titanium(IV) dichloride and n‐butyllithium. The characterization was accomplished by proton nuclear magnetic resonance spectroscopy (¹H NMR), infrared spectroscopy (FTIR), gel permeation chromatography (GPC), differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), and thermogravimetric analysis (TGA). The results indicate that there is a selective saturation of the polybutadiene block over the polystyrene block; this selectivity was determined by the Ti/Li molar ratio and the concentration of Ti. It was observed that the saturation rate of the 1,2‐vinyl was higher than that of the 1,4‐trans and 1,4‐cis poly(butadiene)‐b isomers. The DSC and DMA results indicate that the degree of hydrogenation had a profound effect on the polymer's relaxation behavior. All samples exhibited a biphasic system behavior with two distinct transitions corresponding to the elastomeric and polystyrene blocks. SBEBS copolymers with higher saturation levels (>33%) exhibited a crystalline character. The TGA results indicated a characteristic weight loss temperature in all samples, with slightly higher thermal degradation stabilities in the materials with higher degrees of saturation. POLYM. ENG. SCI., 54:2332–2344, 2014. © 2013 Society of Plastics Engineers     

Effect of the Chord-Brace Angle on the Strength of Rectangular Hollow Sections K- and N-Joints in Galvanized Structures

An important consideration when using hot-dip galvanized tubular structures is the uncertainty of the joint behaviour due to the possible reduction in the global joint resistance produced by the vent holes required for the galvanizing process. This paper assesses the effect on the joint strength of the angle between the brace members and the chord in a K- or N-joints made with rectangular hollow sections. The study is focused on the case when those brace members include characteristic holes required for the hot-dip galvanizing process. To accomplish the objective of the proposed work, some tests on full-scale K- and N-joints, including angles of 35°, 45°, 55° and 90°, were carried out. The experimental work was complemented by a validated numerical simulation in order to give some design recommendations and to extend the research to other joint configurations.     

Enhanced photocatalytic hydrogen production by improving the Pt dispersion over mesostructured TiO2

Among other potential applications, mesoporous titania with high surface area and crystalline framework is attractive in photocatalytic hydrogen production. The mesoporous structure with pore walls formed by nanocrystals of anatase would provide a shorter distance of the electron–hole pairs to reach the photocatalyst surface and a higher surface area to deposit modifiers of its photocatalytic activity. In this work, we have successfully applied a hard-templating pathway to obtain ordered mesoporous titania (m-TiO₂) with high surface area and anatase as main crystalline phase. Subsequently, various amounts of metallic Pt have been deposited using different impregnation methods. All reactions performed exhibit, at short times, a rapid increase in the hydrogen production rate until a point in which a nearly constant value is achieved. The material prepared by the “citrate method”, based on reduction and encapsulation with sodium citrate of Pt nanoparticles before the photocatalytic reaction, leads to the highest hydrogen production rates with the shortest time to reach the change on the trend of the activity curve. The reason of this result is that citrate method provides very good dispersion and, specially, because the Pt nanoparticles are deposited and reduced preferentially within the pores of m-TiO₂, leading to stronger interactions than the other two explored dispersion routes (wetness impregnation and photodeposition). Thus, despite introducing less than half of the theoretical amount of Pt, citrate method produces close to twice the amount of hydrogen obtained by the other dispersion routes. This production capacity is even higher when the amount of Pt loaded is increased, with the optimal concentration being determined as 2% (w/w).