Hydrolysis of sugarcane bagasse using supercritical carbon dioxide to obtain fermentable sugars

This work evaluates the hydrolysis of sugarcane bagasse using supercritical carbon dioxide to obtain fermentable sugars in a single‐step process. The effects of temperature, pressure, despressurization rate, moisture content and reaction time on the amount of fermentable sugars released were assessed. Results obtained showed the feasibility of adopting the present procedure since it produced about 287 g of fermentable sugars per kg of dry bagasse, which corresponds to 60% yield on the basis of total cellulose. Such a result is very attractive from an industrial viewpoint because there is no use of toxic solvent, solvent removal is completed (no residues), and the method has very low water consumption since the process is a solid–gas reaction. © 2012 Society of Chemical Industry     

Effects of Aging and Hypercholesterolemia on Oxidative Stress and DNA Damage in Bone Marrow Mononuclear Cells in Apolipoprotein E-deficient Mice

Recent evidence from apolipoprotein E-deficient (apoE^−/−) mice shows that aging and atherosclerosis are closely associated with increased oxidative stress and DNA damage in some cells and tissues. However, bone marrow cells, which are physiologically involved in tissue repair have not yet been investigated. In the present study, we evaluated the influence of aging and hypercholesterolemia on oxidative stress, DNA damage and apoptosis in bone marrow cells from young and aged apoE^−/− mice compared with age-matched wild-type C57BL/6 (C57) mice, using the comet assay and flow cytometry. The production of both superoxide and hydrogen peroxide in bone marrow cells was higher in young apoE^−/− mice than in age-matched C57 mice, and reactive oxygen species were increased in aged C57 and apoE^−/− mice. Similar results were observed when we analyzed the DNA damage and apoptosis. Our data showed that both aging and hypercholesterolemia induce the increased production of oxidative stress and consequently DNA damage and apoptosis in bone marrow cells. This study is the first to demonstrate a functionality decrease of the bone marrow, which is a fundamental extra-arterial source of the cells involved in vascular injury repair.     

Chitosan–Graphene Oxide Composite Membranes for Solid-Phase Extraction of Pesticides

Solid-phase extraction (SPE) coupled to LC/MS/MS analysis is a valid approach for the determination of organic micropollutants (OMPs) in liquid samples. To remove the greatest number of OMPs from environmental matrices, the development of innovative sorbent materials is crucial. Recently, much attention has been paid to inorganic nanosystems such as graphite-derived materials. Graphene oxide has been employed in water-purification processes, including the removal of several micropollutants such as dyes, flame retardants, or pharmaceutical products. Polysaccharides have also been widely used as convenient media for the dispersion of sorbent materials, thanks to their unique properties such as biodegradability, biocompatibility, nontoxicity, and low cost. In this work, chitosan–graphene oxide (CS_GO) composite membranes containing different amounts of GO were prepared and used as sorbents for the SPE of pesticides. To improve their dimensional stability in aqueous medium, the CS_GO membranes were surface crosslinked with glutaraldehyde. The composite systems were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, thermogravimetric analysis, swelling degree, contact angle, and mechanical measurements. As the GO content increased, a decrease in surface homogeneity, an improvement of mechanical properties, and a reduction of thermal stability of the CS-based membranes were observed. The increased dimensional stability in water, together with the presence of high GO amounts, made the prepared composite membranes more efficacious than the ones based just on CS in isolating and preconcentrating different hydrophilic/hydrophobic pollutants.     

The Arabidopsis Iron-Sulfur (Fe-S) Cluster Gene MFDX1 Plays a Role in Host and Nonhost Disease Resistance by Accumulation of Defense-Related Metabolites

Until recently, genes from the iron-sulfur (Fe-S) cluster pathway were not known to have a role in plant disease resistance. The Nitrogen Fixation S (NIFS)-like 1 (NFS1) and Mitochondrial Ferredoxin-1 (MFDX1) genes are part of a set of 27 Fe-S cluster genes induced after infection with host and nonhost pathogens in Arabidopsis. A role for AtNFS1 in plant immunity was recently demonstrated. In this work, we showed that MFDX1 is also involved in plant defense. More specifically, Arabidopsis mfdx1 mutants were compromised for nonhost resistance against Pseudomonas syringae pv. tabaci, and showed increased susceptibility to the host pathogen P. syringae pv. tomato DC3000. Arabidopsis AtMFDX1 overexpression lines were less susceptible to P. syringae pv. tomato DC3000. Metabolic profiling revealed a reduction of several defense-related primary and secondary metabolites, such as asparagine and glucosinolates in the Arabidopsis mfdx1-1 mutant when compared to Col-0. A reduction of 5-oxoproline and ornithine metabolites that are involved in proline synthesis in mitochondria and affect abiotic stresses was also observed in the mfdx1-1 mutant. In contrast, an accumulation of defense-related metabolites such as glucosinolates was observed in the Arabidopsis NFS1 overexpressor when compared to wild-type Col-0. Additionally, mfdx1-1 plants displayed shorter primary root length and reduced number of lateral roots compared to the Col-0. Taken together, these results provide additional evidence for a new role of Fe-S cluster pathway in plant defense responses.     

Langmuir and Langmuir-Blodgett Films of Polyfluorenes and Their Use in Polymer Light-Emitting Diodes

The Langmuir and Langmuir-Blodgett (LB) film properties of two polyfluorene derivatives, namely poly(2,7-9,9′-dihexylfluorene-dyil) (PDHF) and poly(9,9 dihexylfluorene-dyil-vynilene-alt-1,4-phenylene-vyninele) (PDHF-PV), are reported. Surface pressure (П-A) and surface potential (ΔV-A) isotherms indicated that PDHF-PV forms true monolayers at the air/water interface, but PDHF does not. LB films could be transferred onto various types of substrate for both PDHF and PDHF-PV. Only the LB films from PDHF-PV could withstand deposition of a layer of evaporated metal to form a light-emitting diode (PLED), which had typical rectifying characteristics and emitted blue light. It is inferred that the ability of the polymer to form true monomolecular layers at the air/water interface seems to be associated with the viability of the LB films in PLEDs.     

Differentially CTCF-Binding Sites in Cattle Rumen Tissue during Weaning

The weaning transition in calves is characterized by major structural changes such as an increase in the rumen capacity and surface area due to diet changes. Studies evaluating rumen development in calves are vital to identify genetic mechanisms affected by weaning. This study aimed to provide a genome-wide characterization of CTCF-binding sites and differentially CTCF-binding sites (DCBS) in rumen tissue during the weaning transition of four Holstein calves to uncover regulatory elements in rumen epithelial tissue using ChIP-seq. Our study generated 67,280 CTCF peaks for the before weaning (BW) and 39,891 for after weaning (AW). Then, 7401 DCBS were identified for the AW vs. BW comparison representing 0.15% of the cattle genome, comprising ~54% of induced DCBS and ~46% of repressed DCBS. Most of the induced and repressed DCBS were in distal intergenic regions, showing a potential role as insulators. Gene ontology enrichment revealed many shared GO terms for the induced and the repressed DCBS, mainly related to cellular migration, proliferation, growth, differentiation, cellular adhesion, digestive tract morphogenesis, and response to TGFβ. In addition, shared KEGG pathways were obtained for adherens junction and focal adhesion. Interestingly, other relevant KEGG pathways were observed for the induced DCBS like gastric acid secretion, salivary secretion, bacterial invasion of epithelial cells, apelin signaling, and mucin-type O-glycan biosynthesis. IPA analysis further revealed pathways with potential roles in rumen development during weaning, including TGFβ, Integrin-linked kinase, and Integrin signaling. When DCBS were further integrated with RNA-seq data, 36 putative target genes were identified for the repressed DCBS, including KRT84, COL9A2, MATN3, TSPAN1, and AJM1. This study successfully identified DCBS in cattle rumen tissue after weaning on a genome-wide scale and revealed several candidate target genes that may have a role in rumen development, such as TGFβ, integrins, keratins, and SMADs. The information generated in this preliminary study provides new insights into bovine genome regulation and chromatin landscape.     

Molecularly Imprinted Polymers Based on Chitosan for 2,4-Dichlorophenoxyacetic Acid Removal

The development of low-cost and eco-friendly materials for the removal of pollutants from water is one of the main modern challenges. For this purpose, molecularly imprinted polymers were prepared under optimized conditions starting from chitosan (CS), chemically or ionically modified with glycidyl methacrylate (GMA) or itaconic acid (ITA), respectively. 2,4-Dichlorophenoxyacetic acid (2,4-D) was used as a template, obtaining the CS_GMA and CS_ITA series. The influence of the template concentration on the MIPs’ (molecularly imprinted polymers) morphology, thermal behaviour and swelling ability, as well as on the 2,4-D removal capacity, were analyzed. The amount of the template used for the imprinting, together with the different permeability of the matrices, were the key factors driving the analyte uptake process. Despite the good performance shown by the non-imprinted CS_GMA sample, the best results were obtained when CS_GMA was imprinted with the highest amount (5%) of template (CS_GMA_5). This system was also more efficient when consecutive adsorption experiments were carried out. In addition, CS_GMA_5 had a desorption efficiency of 90–100% when a low pesticide concentration was used. These findings suggest that the presence of imprinted cavities could be useful in improving the performance of sorbent materials making CS_GMA_5 a possible candidate for 2,4-D removal.     

Diffusion Studies of Glucose and Sucrose in Chitosan Membranes and Beads for Enzymatic Production Processes

The diffusion of glucose and sucrose was investigated in membrane and bead experiments. Concentration‐dependent diffusion coefficients of pure glucose and sucrose were determined in precipitated chitosan membranes of varying thickness using diffusion cell experiments. Contrary to fructose, the resulting diffusion coefficients of glucose and sucrose did not reach their free diffusion coefficients at infinite dilution suggesting additional interactions between chitosan and these two sugars. Counter‐diffusion in bead experiments showed a good agreement between predicted and measured data allowing the inclusion of the diffusion data in the simulation of the proposed production process for laminaribiose. In conclusion, the encapsulation in chitosan presented a good trade‐off between increased mass transfer resistance as evaluated by the Thiele modulus and improved thermal stability and antibacterial activity.     

Citizens' views on the practices of zero-grazing and cow-calf separation in the dairy industry: Does providing information increase acceptability?

The primary aim of this study was to assess the influence of provision of information on lay citizens' opinions regarding 2 common management practices, zero-grazing and cow-calf separation. To aid in the interpretation of the findings, our secondary aim was to explore the awareness and opinions of Brazilian citizens about these practices. We surveyed a convenience sample of Brazilian citizens (192 men and 208 women), recruited in a public place, with the majority stating that they were largely unfamiliar with animal production and lived in urban environments. Participants were presented short scenarios with information on the primary production factors and welfare concerns for and against zero-grazing (n = 200) or cow-calf separation (n = 200). Participants were then asked to state their position (reject, indifferent, or support), and to provide the reason(s) justifying their position. Immediately following, participants were provided a short statement describing either zero-grazing or cow-calf separation, depending on what question they responded to in the first part. Two closed questions (Q) followed each of these statements: (Q1) “Are you aware of this practice?” with choices yes, somewhat, or no, and (Q2) “What is your position regarding this practice?” with choices reject, indifferent, or support. Only 31 and 33% of the respondents were aware of zero-grazing and cow-calf separation, respectively. Previous awareness of existence of practice did not influence levels of support. Provision of information resulted in more people rejecting the practices of zero-grazing and cow-calf separation. Participants' main justifications to reject zero-grazing and cow-calf separation focused on perceived negative effects of practices on farm animal welfare and product quality, and loss of naturalness. Survey participants, Brazilians living in urban environments, with little or no association with dairy production, were generally unaware that many cows do not have access to pasture and that cows are separated from their calf at birth. Independent of provision of additional information, most participants did not support these practices. Provision of brief explanatory information played a minor role in influencing people's views, but failed to result in general acceptance.