Screening of supports for the immobilization of pectinmethylesterase from acerola (Malpighia glabra L)

A partially purified extract of pectinmethylesterase (PME) from acerola fruit was immobilized on various supports: glass, celite, chrysotile, agarose, concanavalin A Sepharose 4B, egg shell, polyacrylamide and gelatin. In addition, reticulation with glutaraldehyde was assessed, as well as the use of gelatin in the presence of celite, glass and silica. The highest immobilization yields were obtained when the pectinmethylesterase was immobilized in concanavalin A Sepharose 4B (81.7%) and in gelatin‐water (78.0%). Copyright © 2004 Society of Chemical Industry     

Liquid–liquid extraction of a recombinant protein with reverse micelles

Recombinant cytochrome b₅ was extracted into the reversed micelle phase of an anionic surfactant (AOT) in octane and back-extracted to a final aqueous phase. The extraction of the protein was controlled by an electrostatic mechanism, since it was dependent on the global charge of the protein. This was directly demonstrated by experiments with native and mutant cytochromes obtained by site directed mutagenesis. The back-extraction of cytochrome b₅ to a fresh aqueous phase was decreased by factors that reduced the size of the water pool of the organic phase, such as high salt concentrations (1–2 mol dm^?3 NaCl) and low temperatures (4°C), probably because of an increase in a favourable interaction of this protein with the surfactant at closer distances.     

Spanish Melon Landraces: Revealing Useful Diversity by Genomic,Morphological, and Metabolomic Analysis

Spain is a secondary centre of the diversification of the melon (Cucumis melo L.), with high diversity represented in highly appreciated landraces belonging to the Flexuosus and Ibericus groups. A collection of 47 accessions of Flexuosus, Chate, Piel de Sapo, Tendral, Amarillo, Blanco, and Rochet was analysed using a genotyping-by-sequencing (GBS) approach. A total of 66,971 quality SNPs were identified. Genetic analysis differentiated Ibericus accessions and exotic materials (Ameri, Momordica, Kachri, and Agrestis), while Flexuous accessions shared ancestry between them. Within the Ibericus group, no clear genomic distinction could be identified for the different landraces evaluated, with accessions of different landraces showing high genetic similarity. The morphological characterization confirmed that the external colour and fruit shape had been used as recognition patterns for Spanish melon landraces, but variability within a landrace exists. Differences were found in the sugars and acid and volatile profiles of the materials. Flexuosus and Chate melons at the immature commercial stage accumulated malic acid and low levels of hexoses, while Ibericus melons accumulated high contents of sucrose and citric acid. Specific trends could be identified in the Ibericus landraces. Tendral accumulated low levels of sugars and citric acid and high of malic acid, maintaining higher firmness, Rochet reached higher levels of sugars, and Amarillo tended to lower malic acid contents. Interestingly, high variability was found within landraces for the acidic profile, offering possibilities to alter taste tinges. The main volatile organic compounds (VOCs) in Flexuosus and Chate were aldehydes and alcohols, with clear differences between both groups. In the Ibericus landraces, general trends for VOC accumulation could be identified, but, again, a high level of variation exists. This situation highlights the necessity to develop depuration programs to promote on-farm in situ conservation and, at the same time, offers opportunities to establish new breeding program targets and to take advantage of these sources of variation.     

Surface Engineered Carboxymethylchitosan/Poly(amidoamine) Dendrimer Nanoparticles for Intracellular Targeting

Novel highly branched biodegradable macromolecular systems have been developed by grafting carboxymethylchitosan (CMCht) onto low generation poly(amidoamine) (PAMAM) dendrimers. Such structures organize into sphere‐like nanoparticles that are proposed to be used as carriers to deliver bioactive molecules aimed at controlling the behavior of stem cells, namely their proliferation and differentiation. The nanoparticles did not exhibit significant cytotoxicity in the range of concentrations below 1 mg mL^?1, and fluorescent probe labeled nanoparticles were found to be internalized with highly efficiency by both human osteoblast‐like cells and rat bone marrow stromal cells, under fluorescence‐activated cell sorting and fluorescence microscopy analyses. Dexamethasone (Dex) has been incorporated into CMCht/PAMAM dendrimer nanoparticles and release rates were determined by high performance liquid chromatography. Moreover, the biochemical data demonstrates that the Dex‐loaded CMCht/PAMAM dendrimer nanoparticles promote the osteogenic differentiation of rat bone marrow stromal cells, in vitro. The nanoparticles exhibit interesting physicochemical and biological properties and have great potential to be used in fundamental cell biology studies as well as in a variety of biomedical applications, including tissue engineering and regenerative medicine.     

Electrical Conductivity Measurement Through the Loaded Q Factor of a Resonant Cavity

We present a method for measuring the electrical conductivity of metallic materials that relies on the ratio of two loaded Q factors, Q_R/Q_X, with Q_R corresponding to a TE₀₁₁-mode reference cavity made of aluminum, and Q_X the Q that results upon replacing the aluminum plate with the one fabricated from the material to be examined. Electrical conductivity is mathematically inferred from the ratio Q_R/Q_X where the loaded Q factors are measured by using the transmission-type method. Within a 3.0 percent accuracy, conductivities determined at 8.7 GHz for electrolytic copper (5.6 times 10⁷ S/m) and brass (1.6 times 10⁷ S/m) show to be in good agreement with those reported in the literature.     

Hydroxyapatite Modified with Carbon‐Nanotube‐Reinforced Poly(methyl methacrylate): A Nanocomposite Material for Biomedical Applications

The paper reports on a freeze‐granulation technique to prepare a novel nanocomposite of poly(methyl methacrylate) (PMMA)‐modified hydroxyapatite (HA) with multiwalled carbon nanotubes (MWCNTs) as reinforcement for a new generation biomedical bone cement and implant coatings. By using this technique it is possible to increase material homogeneity and also enhance the dispersion of MWCNTs in the composite matrix. The phase composition and the surface morphology of the nanocomposite material were studied using X‐ray diffraction, field‐emission scanning electron microscopy, and micro‐Raman spectroscopy. Additionally, nanomechanical properties of different concentrations of MWCNT‐reinforced nanocomposite were performed by a nanoindentation technique, which indicates that a concentration of 0.1 wt % MWCNTs in the PMMA/HA nanocomposite material gives the best mechanical properties.     

A methodology to design the link cost functions for impairment aware routing algorithms in optical networks

We propose a methodology to design the link cost function and, consequently, a systematic form to design a RWA algorithm. We call this methodology link cost function design (LCFD) and it consists of four steps: The choice of the link cost function input variables, the expansion of the cost function in terms of a series, the selection of an overall network performance indicator as the optimization target, and finally, the execution of an optimization process to find the series coefficients that optimize the network performance indicator based on off-line network simulations. The optimization process is performed by a computational intelligence technique, the particle swarm optimization. The proposed methodology (LCFD) is used to design an adaptive IA-RWA algorithm, which we call Power Series Routing (PSR). The effectiveness of both methodology and IA-RWA algorithm is investigated. The PSR is compared with other algorithms found in the literature by means of computational simulations and our proposal presented lower blocking probabilities with shorter computation time. Furthermore, we investigate the sensitivity and the ability of the proposed PSR to adapt itself to topological changes in the network due to both link/node addition/failure. We also investigate the behavior of the PSR in a scenario where the traffic load distribution is randomly chosen (non-uniform traffic), and we compared it to other three routing algorithms.     

Experimental Study of a Ka-Band Cylindrical Open Resonator

A study of the electrodynamical properties of a Ka-band gyrotron open resonator was experimentally conducted. Experiments were accomplished to measure resonant frequencies and their respective loaded quality factors for TE modes in the frequency range from 26 to 40 GHz. In particular, a perturbation technique was used to determine the axial, radial and azimuthal electric field profiles, as an identification method of the TE₀₂₁ mode operating around 35 GHz. In any experimental event, good agreement with the values predicted by theory was found.     

Improving user content privacy on social networks using rights management systems

Currently, millions and millions of users are using online social networks to share their thoughts, experiences and content with online friends. Documents, videos, music and pictures are shared online, relying on the privacy and security controls offered by the social network platforms, with little control from the end user. This creates serious privacy concerns, since the control over the content shared online on the social network is out of the hands of the user. In this paper, the authors propose an approach for content privacy shared on social networks that is user-centric and not based on the social network platform. In order to achieve that, an architecture based on a rights management platform capable of enforcing the necessary security and privacy mechanisms that extend the original controls provided by the social network platform will be presented. That way, users will be able to control their privacy settings and protect their own content, even when they are no longer part of the social network (suspending or deleting its account).     

Assessing the use of cutinase reversed micellar catalytic system for the production of biodiesel from triglycerides

BACKGROUND: This work evaluates the use of a reversed micellar catalytic system containing a lipolytic biocatalyst, cutinase, to promote the reaction of triglycerides with methanol, ethanol or butanol for the production of biodiesel in isooctane. RESULTS: The specific activity of cutinase increased with increase of the alcohol chain length, and methanol showed a significant toxicity toward the enzyme leading to a specific activity decrease for high concentrations of this alcohol, which did not occur when ethanol or butanol were used. The composition of the mixture was analyzed and it was shown that, although the reaction could proceed without water, the presence of water allowed higher reaction rates and higher conversions, probably because water helps to maintain both the micellar structure and lipase conformation. Excess water, however, had a deleterious effect on conversion. CONCLUSION: The influence of water and methanol, apart from micelle structure, was found to be linked to partition effects of diglyceride and monoglyceride, which may also have a significant impact on the reaction rate. Copyright © 2010 Society of Chemical Industry