Diferenciación molecular de Lemna aequinoctialis y L. Valdiviana (lemnaceae) por patrones proteicos

El estudio se llevó a cabo en el Laboratorio de Genética Molecular de la Universidad Nacional, Heredia, Costa Rica. Se utilizaron plantas acuáticas macrófitas de Lemna valdiviana y L. aequinoctialis previamente identificadas. Estas especies habitan en aguas ricas en sales disueltas y aguas servidas. Recientemente se les consideró como un indicador de la contaminación ocasionada por pesticidas y herbicidas en el agua. La composición proteica llega a niveles entre 38 y 43% de materia seca, importante para diversos usos. La extracción de proteínas totales, por medio de electroforesis discontinua en gel de poliacrilamida, se realizó en condiciones reductoras con SDS (SDS-PAGE). Los geles separadores empleados fueron al 8 y 10%, gel espaciador al 4% y la tinción se efectuó con azul commassie. Los diversos patrones proteicos reflejaron diferencias genéticas entre ambas especies que se pueden deber a las diferencias de hábitat y de reproducción.

Caracterización molecular por patrones electroforéticos de isoenzimas esterasas en Lemna aequinoctialis y Lemna valdiviana (lemnaceae) de Costa Rica (ING)

The Lemnaceae family lacks morphologic and anatomical characteristics with comparative aims and for that reason the molecular studies has been necessary a differentiation. In Costa Rica there are two species of Lemna: Lemna aequinoctialis and Lemna valdiviana. With the objective of a molecular characterization and differentiation of both species were extracted isoenzymes esterases. The study was carried out in the Molecular Genetics Laboratory of the School of Biological Sciences at Universidad Nacional, Heredia, Costa Rica. The technical electrophoresis in gel of polyacrylamida SDS-PAGE was used. It was difference in the pattern of isoenzymes between both species. According to previous molecular studies based on morphology and anatomy, flavonoides, isoenzymes, and DNA sequences of certain genes both species are very different; in addition they belong to different monophyletics groups. On the other hand, the importance of this molecular characterization is its possible use in water treatment, because the esterases have had important in the bioremediation. Also, species of the Lemnaceae family are used in the water treatment like bioremediation.

Development of edible films based on differently processed Atlantic halibut (Hippoglossus hippoglossus) skin gelatin

The gelatin prepared from the skins of the Atlantic halibut (Hippoglossus hippoglossus) was investigated for the development of edible films plasticized with 30g sorbitol/100g gelatin. Two types of dry gelatin preparations were obtained depending on whether an intermediate evaporation step at 60 degrees C in the drying procedure is included or not. The amino acid composition, molecular weight distribution (determined by SDS-polyacrylamide gel electrophoresis) and glass transition temperature (determined by differential scanning calorimetry) of the gelatins were determined and related to some physical properties of the resulting films. The gelatin extracted from the halibut skins showed a suitable filmogenic capacity, leading to transparent, weakly colored, water-soluble and highly extensible films. The intermediate evaporation step at 60 degrees C induced thermal protein degradation, causing the resulting films to be significantly less resistant and more extensible. No differences in water vapor permeability, viscoelasticity, glass transition or color properties were evidenced between the two gelatins tested. (C) 2007 Elsevier Ltd. All rights reserved.

Enhancing an Incremental Clustering Algorithm for Web Page Collections

With the size and state of the Internet today, a good quality approach to organizing this mass of information is of great importance. Clustering web pages into groups of similar documents is one approach, but relies heavily on good feature extraction and document representation as well as a good clustering approach and algorithm. Due to the changing nature of the Internet, resulting in a dynamic dataset, an incremental approach is preferred. In this work we propose an enhanced incremental clustering approach to develop a better clustering algorithm that can help to better organize the information available on the Internet in an incremental fashion. Experiments show that the enhanced algorithm outperforms the original histogram based algorithm by up to 7.5%.

Sequential release of BMP-7 and VEGF from the PLGA/AK-Gelatin Composite Scaffolds

Vascular endothelial growth factor (VEGF) and bone morphogenetic proteins (BMP-7) are key regulators of angiogenesis and osteogenesis during bone regeneration. The aim of this study was to investigate the possibility of realizing sequential release of the two growth factors using a novel composite scaffold. Poly(lactic-co-glycolic acid) (PLGA)-Akermanite (AK) microspheres were used to make the composite scaffold, which was then loaded with BMP-7, followed by embedding in a gelatin hydrogel matrix loaded with VEGF. The release profiles of the growth factors were studied and selected osteogenic related markers of bone marrow stromal cells (BMSCs) were analysed. It was shown that the composite scaffolds exhibited a fast initial burst release of VEGF within the first 3 days and a sustained slow release of BMP-7 over the full period of 20 days. The in vitro proliferation and differentiation of the BMSCs cultured in the osteogenic medium were enhanced by 1 to 2 times, resulting from the additionally and sequentially release of growth factors from the PLGA-AK/gelatin composite scaffolds.

Effective adsorption of sodium dodecylsulfate (SDS) by hydrocalumite (CaAl-LDH-Cl) induced by self-dissolution and re-precipitation mechanism

Hydrocalumite (CaAl-LDH-Cl) were synthesized through a rehydration method involving a freshly prepared tricalcium aluminate (C3A) with CaCl2 solution. To understand the intercalation behaviour of sodium dodecylsulfate (SDS) with CaAl-LDH-Cl, X-ray diffraction (XRD), Fourier transform infrared (FTIR), scanning electron microscopy (SEM), transmission electron microscope (TEM), X-ray photoelectron spectroscopy (XPS), inductively coupled plasma-atomic emission spectrometer (ICP) and elemental analysis have been undertaken. The sorption isotherms with SDS reveal that the maximum sorption amount of SDS by CaAl-LDH-Cl could reach 3.67 mmol•g-1. The results revealed that CaAl-LDH-Cl holds a self-dissolution property, about 20-30% of which is dissolved. And the dissolved Ca2+, Al3+ ions are combined with SDS to form CaAl-SDS or Ca-SDS precipitation. It has been highlighted that the composition of resulting products is strongly dependent upon the SDS concentration. With increasing SDS concentrations, the main resulting product changes from CaAl-SDS to Ca-SDS, and the value of interlayer spacing increased to 3.27 nm.

Front page schools, back page schools : a case study of factors perceived to affect academic performance in five Papua New Guinea secondary schools

Papua New Guinea has reformed its colonial established education system and made huge investments with the help of donors to achieve equal access and quality education for all its citizens. Despite this national aspiration and these policy reforms and investments, secondary schools that enrol grade 9 students who are relatively equal in education ability show huge disparities in their grade 10 academic performances. This study examined perceptions of students, teachers and principals regarding factors affecting the disparity in academic performance in the context of a developing country. The central question for the study is: What are the perceptions of students and teachers of the factors that affect disparities in secondary schools' academic performance? This qualitative case study involved two high and three low academic performing secondary schools in Western Highlands Province of Papua New Guinea. Primary data were collected through focus groups and semi-structured interviews involving 112 participants. Students and teachers are key participants in this study, as it intends to find out the realities of schools, yet they are an under-researched group. A postcolonial and sense of community conceptual framework was developed for the analysis of the participants. perceptions. In addition, scholarship on school effectiveness and equity in education informed the interpretation of the findings. Three themes were evident in participants. views. First, participants expressed their view that differences in academic performance were related to the adequacy and equitability of resources. The inequities in resource inputs led some of them to coin the metaphor of .back page and front page. schools. Second, many expressed the view that deficiencies in implementing bilingual education, given the difficulty of catering for 800 vernacular languages, contribute to poor English proficiency and subsequent poor academic performance. Finally, participants believed that, in order to have a positive school culture, it is necessary for educators to recognise and respect contemporary students. identities, communal/tribal membership and needs. This study has implications for national education policy on resource allocation to address equality and equity, bilingual education and teacher education. Moreover, as the study found that high academic performance in this context is also influenced by intra-school social relationships, these relationships need to be nurtured. When appropriately nurtured, they become an important factor in sustaining quality education for all secondary school students. This thesis has laid the foundations for further research and invites further investigations into policy and implementation of school reforms aimed at improving academic achievement.

Like our page : using Facebook to support first year students in their transition to higher education

Facebook is approaching ubiquity in the social habits and practice of many students. However, its use in higher education has been criticised (Maranto & Barton, 2010) because it can remove or blur academic boundaries. Despite these concerns, there is strong potential to use Facebook to support new students to communicate and interact with each other (Cheung, Chiu, & Lee, 2010). This paper shows how Facebook can be used by teaching staff to communicate more effectively with students. Further, it shows how it can provide a way to represent and include beginning students’ thoughts, opinions and feedback as an element of the learning design and responsive feed-forward into lectures and tutorial activities. We demonstrate how an embedded social media strategy can be used to complement and enhance the first year curriculum experience by functioning as a transition device for student support and activating Kift’s (2009) organising principles for first year curriculum design.

Silver Gelatin Print: A group exhibition curated by Karen Milder that investigates and captures the traditional processes using photograms, liquid emulsion, toning, hand-colouring and film. Part of the Queensland Festival of Photography 4 (QFP4).

Pillar of salt: (3 hand-applied silver gelatin photographs) Statement: For women moving into new experiences and spaces, loss and hardship is often a price to be paid. These courageous women look back to things they have overcome in order to continue to grow.

Reading : From Turning the Page to Touching the Screen

This chapter considers the ways in which contemporary children’s literature depicts reading in changing times, with a particular eye on the cultural definitions of ‘reading’ being offered to young people in the age of the tablet computer. A number of picture books, in codex and app form, speak to changing times for reading by their emphasis on the value of books and reading as technologies of literature and of the self. Attending to valuations of literacy and literature within children’s texts provides insight into anxieties about books in the electronic age.

Copyright protections and disability rights : turning the page to a new international paradigm

This paper argues that governments around the world need to take immediate coordinated action to reverse the 'book famine.' There are over 129 million book titles in the world, but persons with print disabilities can obtain less than 7% of these titles in formats that they can read. The situation is most acute in developing countries, where less than 1% of books are accessible. Two recent international developments – the United Nations Convention on the Rights of Persons with Disabilities (‘CRPD’) and the new Marrakesh Treaty to Facilitate Access to Published Works for Persons who are Blind, Visually Impaired, or otherwise Print Disabled (somewhat ironically nicknamed the ‘VIP Treaty’) – suggest that nation states are increasingly willing to take action to reverse the book famine. The Marrakesh Treaty promises to level out some of the disparity of access between people in developed and developing nations and remove the need for each jurisdiction to digitise a separate copy of each book. This is a remarkable advance, and suggests the beginnings of a possible paradigm shift in global copyright politicsmade all the more remarkable in the face of heated opposition by global copyright industry representatives. Now that the Marrakesh Treaty has been concluded, however, we argue that a substantial exercise of global political will is required to (a) invest the funds required to digitise existing books; and (b) avert any further harm by ensuring that books published in the future are made accessible upon their release.

Gelatin-methacrylamide hydrogels as potential biomaterials for fabrication of tissue-engineered cartilage constructs

Gelatin-methacrylamide (gelMA) hydrogels are shown to support chondrocyte viability and differentiation and give wide ranging mechanical properties depending on several cross-linking parameters. Polymer concentration, UV exposure time, and thermal gelation prior to UV exposure allow for control over hydrogel stiffness and swelling properties. GelMA solutions have a low viscosity at 37 °C, which is incompatible with most biofabrication approaches. However, incorporation of hyaluronic acid (HA) and/or co-deposition with thermoplastics allows gelMA to be used in biofabrication processes. These attributes may allow engineered constructs to match the natural functional variations in cartilage mechanical and geometrical properties.