Genetic approaches to improve salinity tolerance in plants
- Authors: Kumar, Ashwani , Gupta, Aditi , Azooz, M M , Sharma, S , Ahmad, Parvaiz , Dames, Joanna F
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , book chapter
- Identifier: http://hdl.handle.net/10962/453449 , vital:75255 , ISBN , https://doi.org/10.1007/978-1-4614-6108-1_4
- Description: Abiotic stress tolerance in plants is gaining importance day by day. Different techniques are being employed to develop salt tolerant plants that directly or indirectly combat global food problems. Advanced comprehension of stress signal perception and transduction of associated molecular networks is now possible with the development in functional genomics and high throughput sequencing. In plant stress tolerance various genes, proteins, transcription factors, DNA histone-modifying enzymes, and several metabolites are playing very important role in stress tolerance. Determination of genomes of Arabidopsis, Oryza sativa spp. japonica cv. Nipponbare and integration of omics approach has augmented our knowledge pertaining to salt tolerance mechanisms of plants in natural environments. Application of transcriptomics, metabolomics, bioinformatics, and high-through-put DNA sequencing has enabled active analyses of regulatory networks that control abiotic stress responses. To unravel and exploit the function of genes is a major challenge of the post genomic era. This chapter therefore reviews the effect of salt stress on plants and the mechanism of salinity tolerance along with contributory roles of QTL, microRNA, microarray and proteomics.
- Full Text:
- Date Issued: 2013
Teenage pregnancy
- Authors: Macleod, Catriona I
- Date: 2013
- Language: English
- Type: Text
- Identifier: vital:6301 , http://hdl.handle.net/10962/d1015906
- Description: In a book on preventing early pregnancy and poor reproductive outcomes in developing countries, the World Health Organisation (2011) declares that ‘adolescent pregnancy’ contributes to maternal, perinatal and infant mortality, and to a vicious cycle of poverty and ill-health. This statement reflects the common public assumption that ‘teenage pregnancy’ represents an individual, social, health, educational and financial risk that requires remediation. This kind of public perception is spurred by media coverage in which young girls with large protruding stomachs are etched in profile and stories of calamity are told (e.g. Time (21 June 2005) magazine). And yet the very notion of 'teenage pregnancy' is a relatively recent one. Depending on the country one talks about, it has been around since between the 1960s and 1980s. In the United States, for example, the rise of ‘teenage pregnancy’ as a social problem was associated with a shift in gendered power relations. Prior to the late 1960s the morally loaded concepts of 'unwed mother' and 'illegitimate child' were used to describe young women who conceived. For the most part, young pregnant women were excluded from society, with the accompanying shame around the lack of proper conjugal arrangements. The use of the term 'teenage pregnancy' removed the implied moral judgment and replaced it with seeming scientific neutrality. Young pregnant women now became publicly visible and thus the object of scientific scrutiny (Arney & Bergen, 1984).
- Full Text:
- Date Issued: 2013
Ethical deliberations in environmental education workplaces: a case story of contextualised and personalised reflexivity
- Authors: Olvitt, Lausanne L
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , book chapter
- Identifier: http://hdl.handle.net/10962/437421 , vital:73377 , ISBN 9789086867578 , https://doi.org/10.3920/9789086867578_0010
- Description: This chapter explores the fluidity and complexity of individual ethical deliberations in an environmental education workplace and ‘teases out’the associated learning processes. Based on the author’s recent doctoral research, the chapter tells the story of one South African environmental educator grappling with environmentoriented ethical tensions in his work. These ten-sions range from immediate officebased concerns such as paper wastage, to wider concerns such as lowering his carbon footprint through his choice of transport. The environmental educator has recently completed a one-year part-time course in environmental education. Does the course’s new capital of concepts and terminology influence his ethical deliberations? Does learning about environmental philosophies and other people’s ethical dilemmas support him to deepen his engage-ment with ethical tensions in his ownwork? The case study suggests that course-based learning processes are not espe-cially influential until they interface with the multi-layered soci-ocultural and historical dynamics in work-based and home-based ethical deliberations. Deciding what is ‘right’, and then teaching others about that ‘rightness’ is not as simple as know-ing the facts or norms, and acting on them. Past experiences, cultural norms, religious convictions, power gradients and even logistical constraints, all influence the nature and outcome of individual ethical deliberations, as do people’s future aspira-tions and their professional identities as environmental educa-tors.
- Full Text:
- Date Issued: 2012
Targeting conserved pathways as a strategy for novel drug development: disabling the cellular stress response:
- Authors: Edkins, Adrienne L , Blatch, Gregory L
- Date: 2012
- Language: English
- Type: text , book
- Identifier: http://hdl.handle.net/10962/165129 , vital:41211 , ISBN 978-3-642-28174-7 , DOI: 10.1007/978-3-642-28175-4_4
- Description: The ability to respond to and cope with stress at a molecular level is essential for cell survival. The stress response is conserved across organisms by the expression of a group of molecular chaperones known as heat shock proteins (HSP). HSP are ubiquitous and highly conserved proteins that regulate cellular protein homeostasis and trafficking under physiological and stressful conditions, including diseases such as cancer and malaria. HSP are good drug targets for the treatment of human diseases, as the significant functional and structural data available suggest that they are essential for cell survival and that, despite conservation across species, there are biophysical and biochemical differences between HSP in normal and disease states that allow HSP to be selectively targeted. In this chapter, we review the international status of this area of research and highlight progress by us and other African researchers towards the characterisation and targeting of HSP from humans and parasites from Plasmodium and Trypanosoma as drug targets.
- Full Text:
- Date Issued: 2012
Cultural importance of non-timber forest products: opportunities they pose for bio-cultural diversity in dynamic societies
- Authors: Cocks, Michelle L , López, Citlalli , Dold, Anthony P
- Date: 2011
- Language: English
- Type: text , book
- Identifier: http://hdl.handle.net/10962/141453 , vital:37973 , ISBN 9783642179822 , DOI: 10.1007/978-3-642-17983-9_5
- Description: There is an increasing awareness that monetary value does not fully represent the complete value and significance of NTFPs. Consequently, there is growing interest in the cultural dimensions of biodiversity and the role that it plays in human well-being. This chapter presents two case studies, one on traditional brooms in South Africa, and the other on amate paper in Mexico, to demonstrate the importance of cultural values on driving demand for NTFPs. Because cultural values are so deeply embedded, the demand for culturally valued NTFPs continue across the rural-urban divide, and are maintained even by modernising urban communities. This poses particular challenges, not only for conservation of the NTFPs, but also to sustain cultural diversity in a rapidly changing world.
- Full Text:
- Date Issued: 2011
Contemporary precision, bias and accuracy of minimum post-mortem intervals estimated using development of carrion-feeding insects
- Authors: Villet, Martin H , Richards, Cameron S , Midgley, John M
- Date: 2010
- Subjects: To be catalogued
- Language: English
- Type: text , book chapter
- Identifier: http://hdl.handle.net/10962/442769 , vital:74032 , ISBN 978-1-4020-9684-6 , https://doi.org/10.1007/978-1-4020-9684-6_7
- Description: Medicocriminal forensic entomology focuses primarily on providing evidence of the amount of time that a corpse or carcass has been exposed to colonization by insects, which helps to estimate the post mortem interval (PMI). Specifically, the estimate is of a minimum post mortem interval (PMImin), because death may occur a variable amount of time before colonization (Fig. 7.1); the maximum post mortem interval (PMImax) is estimated using the time that the person was last seen alive. Forensic entomology derives the bulk of its evidence from two sources: the ecological succession of carrion insect communities and the development of immature insects (Byrd and Castner 2001; Catts and Haskel 1990; Smith 1986). This chapter is concerned with assessing the confidence that can be placed in the accuracy of estimates derived from insect development. (Schoenly et al. 1996) dealt with this theme in succession-based estimates of PMImin.
- Full Text:
- Date Issued: 2010
Cultivation of medicinal plants as a tool for biodiversity conservation and poverty alleviation in the Amatola region, South Africa:
- Authors: Wiersum, K Freerk , Dold, Anthony P , Husselman, Madeleen , Cocks, Michelle L
- Date: 2010
- Language: English
- Type: text , book
- Identifier: http://hdl.handle.net/10962/141489 , vital:37979 , ISBN 9781402054488 , https://library.wur.nl/ojs/index.php/frontis/issue/view/232
- Description: This paper describes the assumptions and results of a study to assess whether cultivation of medicinal plants can serve as a tool for combined biodiversity conservation and poverty alleviation. The study was carried out in the Amatola region of Eastern Cape, South Africa, where sustained beliefs in medicinal plant use, also under non-traditional conditions, has resulted in an increase in commercial demands. It was based on the assumption of poverty alleviation not only referring to an increase in income and labour, but also an increase in social capital and human dignity. The study assessed the local perceptions of the use and cultivation of medicinal plants and the need for conservation of these plants, as well as the features of already ongoing cultivation practices and options for increased cultivation. It consisted of participatory assessments in three villages involving around 250 persons and participatory trials with 14 rural women selling medicinal plants on urban markets. The study indicated that the growing demand for medicinal plants is related to the great cultural significance attached to medicinal plants.
- Full Text:
- Date Issued: 2010
The utility of Coleoptera in forensic investigations
- Authors: Midgley, John M , Richards, Cameron S , Villet, Martin H
- Date: 2010
- Subjects: To be catalogued
- Language: English
- Type: text , book chapter
- Identifier: http://hdl.handle.net/10962/442783 , vital:74033 , ISBN 978-1-4020-9684-6 , https://doi.org/10.1007/978-1-4020-9684-6_4
- Description: Forensic entomology is a developing field of forensic science, so there are many avenues to investigate. These avenues include novel directions that have never been addressed, as well as more critical and rigorous research into areas which have already been explored. Most research in forensic entomology has focused on flies, and beetles (Coleoptera) have been at best under-emphasized. A good example of this is the review by Smith (1986), where 70 pages are dedicated to Diptera and only 12 to Coleoptera; this situation has changed little in the subsequent 20 years. To contextualize the neglect, throughout the world there are at least as many species of Coleoptera that may visit a particular carcass as Diptera (Braack 1986; Louw and van der Linde 1993; Bourel et al. 1999; Lopes de Carvalho et al. 2000; Pérez et al. 2005; Shea 2005; Watson and Carlton 2005a; Salazar 2006; Martinez et al. 2007). A common assumption underlying the neglect of Coleoptera is that Diptera locate corpses faster, and thus give a more accurate estimate of minimum Post Mortem Interval (PMImin). Recent observations (Midgley and Villet 2009b) have shown that Thanatophilus micans (Silphidae) can locate corpses and start breeding within 24 h of death, and thus the potential utility of estimates based on this species is equal to that of those based on flies.
- Full Text:
- Date Issued: 2010
What is biocultural diversity?: a theoretical review
- Authors: Cocks, Michelle L
- Date: 2010
- Language: English
- Type: text , book
- Identifier: http://hdl.handle.net/10962/141475 , vital:37975 , ISBN 9781441957009 , DOI: 10.1007/978-1-4419-5701-6_5
- Description: Over the past decade, scholars from various fields have increasingly emphasized the detrimental effects of global socioeconomic processes on biodiversity. The industrial revolution, the demographic explosion of Homo sapiens, and the rise of the global exchange economy are all implicated as major factors that influence the loss of species diversity. From the late 1980s onward, biosystematics and conservation biology have successfully brought this concern to the attention of the public. Biodiversity is increasingly recognized as an essential resource on which families, communities, and nations depend. Biologists, ecologists, and conservationists have further recognized that solutions to biological problems lie in the mechanisms of social, cultural, and economic systems, which has led to attempts to place a monetary value on species and ecosystems to calculate the cost of using and conserving biodiversity.
- Full Text:
- Date Issued: 2010
South Africa: Applied competence as the guiding framework for environmental and sustainability education
- Authors: Lotz-Sisitka, Heila , Raven, Glenda
- Date: 2009
- Subjects: To be catalogued
- Language: English
- Type: text , book chapter
- Identifier: http://hdl.handle.net/10962/437395 , vital:73375 , ISBN 978-1-4020-8194-1 , https://doi.org/10.1007/978-1-4020-8194-1_22
- Description: Following the demise of apartheid rule in South Africa in 1994, the new government adopted the South African Qualifications Act (RSA, 1995a) which established the South African Qualifications Authority (SAQA). The SAQA was tasked with the responsibility for developing and im-plementing a national qualifications framework (NQF) based on princi-ples of quality, equity and redress. A primary objective of the NQF was to establish a portable and responsive model for lifelong learning and one which could recognize prior learning according to an outcomes-based education and training framework. In addition to this mandate and amongst other responsibilities, SAQA has had a responsibility to design and develop qualifications that respond to the environmental rights and sustainable development clauses of the Constitution and as-sociated national policies. Through this, environment and sustainability education was placed on the national education and training agenda (see Lotz-Sisitka and Olvitt in this volume).
- Full Text:
- Date Issued: 2009
South Africa: Strengthening responses to sustainable development policy and legislation
- Authors: Lotz-Sisitka, Heila , Olvitt, Lausanne L
- Date: 2009
- Subjects: To be catalogued
- Language: English
- Type: text , book chapter
- Identifier: http://hdl.handle.net/10962/437382 , vital:73374 , ISBN 978-1-4020-8194-1 , https://doi.org/10.1007/978-1-4020-8194-1_23
- Description: A key objective of the newly established South African national qualifi-cations framework (NQF) is to enable the transformation of society, fol-lowing the demise of apartheid in 1994. Through the South African Constitution, which enshrines the right to a healthy environment for all citizens, and the sustainable utilization of resources for current and fu-ture generations (RSA, 1996), South African society adopted a devel-opment path that is oriented towards sustainable development. The de-velopment and implementation of the NQF (established by the South African Qualifications Authority Act in 1995) has involved various initia-tives to design and develop qualifications that respond to the environ-mental rights and sustainable development clauses of the Constitution and associated national policy. The past 10 years have been an active period for reconceptualizing education and training in South Africa, par-ticularly in the previously neglected1 area of workplacebased learning. New structures were put in place to develop and approve flexible and portable qualifications in unit-standard format, new service delivery structures and mechanisms have been established which allow for flex-ible forms of programme delivery and new learning programmes have been designed to respond to the outcomes-based, flexible format of the NQF. The NQF has created new opportunities for lifelong learning and new possibilities for those formerly disadvantaged by apartheid exclu-sionary policies and systems to gain access to education and training, and recognition for their skills and competencies. It has also created the space for new innovative programmes to emerge that respond to emerging issues in society, such as increased environmental degradation, increased health risks and new social and economic challenges.
- Full Text:
- Date Issued: 2009
The unit-based sustainability assessment tool and its use in the UNEP mainstreaming environment and sustainability in African universities partnership
- Authors: Togo, Muchaiteyi , Lotz-Sisitka, Heila
- Date: 2009
- Subjects: To be catalogued
- Language: English
- Type: text , book chapter
- Identifier: http://hdl.handle.net/10962/437409 , vital:73376 , ISBN 978-1-4020-8194-1 , https://doi.org/10.1007/978-3-319-02375-5_15
- Description: This paper reports on the development and use of a Unit-based Sustainability Assessment Tool (USAT) for establishing the status of Education for Sustainable Development initiatives and sustainable development practices in universities. The tool was developed for use in the Swedish/Africa International Training Programme (ITP) on ‘Education for Sustainable De-velopment in Higher Education’ and complements the UNEP Mainstreaming Environment and Sustainability into African Universities (MESA) ‘Education for Sustainable Development Innovations Programmes for Universities in Africa’ materials. The USAT facilitates a quick assessment of the level of inte-gration of sustainability issues in university functions and op-erations, both to benchmark sustainability initiatives and identi-fy new areas for action or improvement. It is based on a unit-based framework which allows for sustainability assessments to be done per division, unit, department, or faculty within uni-versities. Collectively, the unit-based assessments provide for development of an institution wide picture of university sus-tainability.
- Full Text:
- Date Issued: 2009
Participation, situated culture, and practical reason
- Authors: Lotz-Sisitka, Heila , O'Donoghue, Rob B
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , book chapter
- Identifier: http://hdl.handle.net/10962/437436 , vital:73378 , ISBN 978-1-4020-6415-9 , https://link.springer.com/chapter/10.1007/978-1-4020-6416-6_7
- Description: This chapter examines the emergence of participatory education as both a central feature and a terrain of ambivalence within the develop-ing landscape of environmental education in South Africa. From its roots in nature experience activities through to more socially critical forms of environmental education, participatory imperatives in this area have yet to address sufficiently the conceptual and practical challenges inherent in pedagogies of participation. We argue that more recent de-velopments reveal similar anomalies, such that participatory education in South Africa has now become an idealised and techniqued logic of practice.
- Full Text:
- Date Issued: 2008
Customary Sea Tenure in Oceania as a Case of Rights-based Fishery Management: Does it Work?
- Authors: Shankar, Aswani
- Date: 2005
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/439071 , vital:73542 , xlink:href="https://doi.org/10.1007/s11160-005-4868-x"
- Description: This paper outlines the general characteristics of customary sea tenure (CST) in Oceania and identifies areas in which these characteristics overlap with modern rights-based fisheries management systems such as ITQs and CDQs. It also examines the effectiveness of CST regimes at regulating marine resource use and access by focusing on a particular case from the Solomon Islands. The institutional robustness or vulnerability of CST is assessed by examining various performance criteria for two communities in the Roviana Lagoon, Western Solomons. These criteria include people’s (1) settlement patterns in relation to their property, (2) cultural consensus, (3) cultural attitudes with regard to governance and management, and (4) fishing efforts and yields. The results show that a number of historical processes have shaped CST systems into heterogeneous and dynamic institutions, and that CST regimes can vary even on small geographical scales. Understanding the circumstances in which CST regimes are more likely to be successful has facilitated the design and implementation of co-management fishery prescriptions (MPAs) for protecting particular species and habitats in the region. More generally, the paper proposes that by discerning the effectiveness of local governance institutions at regulating resource use and access – taking into consideration that these are embedded in particular historical and political contexts – we can better predict whether or not an introduced fishery management system will work. This knowledge can also assist in designing hybrid management schemes that cross-fertilize community-based management, modern rights-based fishery management (e.g., ITQs and CDQs), and other government regulations. This integration is particularly relevant when these policies are to be implemented in coastal communities that have or have had traditional rights-based fishery management systems of their own and/or are more socio-culturally homogeneous. Given the long history of failed fishery management, it is now of vital importance to design innovative fishery management prescriptions that integrate natural and social science research more comprehensively.
- Full Text:
- Date Issued: 2005
Common Property Models of Sea Tenure: A Case Study from the Roviana and Vonavona Lagoons, New Georgia, Solomon Islands
- Authors: Shankar, Aswani
- Date: 1999
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/439865 , vital:73715 , xlink:href="https://doi.org/10.1023/A:1018727607651"
- Description: In recent decades, Pacific Region indigenous sea tenure regimes have received considerable attention from social scientists who believe thatmarine-localized common entitlements and fishing practices can aid modern littoral fisheries management. The endorsement of sea tenure institutions as managerial tools, however, has proceeded without adequate consideration of their vulnerability to social and economic changes. The general view held by researchers is that Pacific Island Sea tenure regimes are generally undermined by the influence of exogenous forces resulting in an open-access commons. In this article, it is argued that the contemporary transformation of sea tenure regimes emerges not only from exogenous agency, but from a complex set of autochthonous processes. A case study from New Georgia, Solomon Islands, is presented to show how sea tenure regimes can vary within an ethnically and culturally homogeneous region. Three tenure models are presented to show how different pre- and post-European contact regional settlement patterns, localized processes of political expansion and contraction, and dynamic indigenous sociocultural principles have resulted in institutional differences between each sea tenure model. The effect of the market economy on the organizational structure and managerial outcomes of each model also is discussed.
- Full Text:
- Date Issued: 1999
Carbon nanotube-enhanced photoelectrochemical properties of metallo-octacarboxyphthalocyanines
- Authors: Mphahlele, Nonhlanhla E. , Roux, Lukas Le , Jafta, Charl J. , Cele, Leskey , Mathe, Mkhulu K. , Nyokong, Tebello , Kobayashi, Nagao , Ozoemena, Kenneth I.
- Language: English
- Type: Article
- Identifier: vital:7312 , http://hdl.handle.net/10962/d1020538
- Description: The photoelectrochemistry of metallo-octacarboxyphthalocyanines (MOCPc, where M = Zn or Si(OH)2) integrated with MWCNTs for the development of dye-sensitized solar cells (DSSCs) is reported. The DSSC performance (obtained from the photo-chronoamperometric and photo-impedimetric data) decreased as ZnOCPc > (OH)2SiOCPc. The incorporation of the MWCNTs on the surface of the TiO2 film (MOCPc–MWCNT systems) gave higher photocurrent density than the bare MOCPc complexes. Also, from the EIS results, the MOCPc–MWCNT hybrids gave faster charge transport kinetics (approximately three times faster) compared to the bare MOCPc complexes. The electron lifetime was slightly longer (ca. 6 ms) at the ZnOCPc systems than at the (OH)2SiOCPc system (ca. 4 ms) meaning that the presence of the MWCNTs on the surface of the TiO2 film did not show any significant improvement on preventing charge recombination process. , Original publication is available at http://dx.doi.org/10.1007/s10853-013-7710-1
- Full Text: false
Electrode modification using nanocomposites of electropolymerised cobalt phthalocyanines supported on multiwalled carbon nanotubes
- Authors: Nyoni, Stephen , Mashazi, Philani N , Nyokong, Tebello
- Language: English
- Type: Article
- Identifier: vital:7293 , http://hdl.handle.net/10962/d1020356
- Description: A polymer of tetra(4)-(4,6-diaminopyrimidin-2-ylthio) phthalocyaninatocobalt(II) (CoPyPc) has been deposited over a multiwalled carbon nanotube (MWCNT) platform and its electrocatalytic properties investigated side by side with polymerized cobalt tetraamino phthalocyanine (CoTAPc). X-ray photoelectron spectroscopy, scanning electron microscopy and cyclic voltammetry studies were used for characterization of the prepared polymers of cobalt phthalocyanine derivatives and their nanocomposites. l-Cysteine was used as a test analyte for the electrocatalytic activity of the nanocomposites of polymerized cobalt phthalocyanines and multiwalled carbon nanotubes. The electrocatalytic activity of both polymerized cobalt phthalocyanines was found to be superior when polymerization was done on top of MWCNTs compared to bare glassy carbon electrode. A higher sensitivity for l-cysteine detection was obtained on CoTAPc compared to CoPyPc. , Original publication is available at http://dx.doi.org/10.1007/s10008-015-2985-6
- Full Text: false
Fluorescence Behaviour and Singlet Oxygen Production of Aluminium Phthalocyanine in the Presence of Upconversion Nanoparticles
- Authors: Watkins, Zane , Taylor, Jessica , D’Souza, Sarah , Britton, Jonathan , Nyokong, Tebello
- Language: English
- Type: Article
- Identifier: vital:7288 , http://hdl.handle.net/10962/d1020337
- Description: NaYF4:Yb/Er/Gd upconversion nanoparticles (UCNP) were synthesised and the photoemission stabilised by embedding them in electrospun fibers. The photophysical behaviour of chloro aluminium tetrasulfo phthalocyanine (ClAlTSPc) was studied in the presence of UCNPs when the two are mixed in solution. The fluorescence quantum yield value of ClAlTSPc decreased in the presence of UCNPs due to the heavy atom effect of UCNPs. This effect also resulted in increase in triplet quantum yields for ClAlTSPc in the presence of UCNPs. The fluorescence lifetimes for UCNPs were shortened at 658 nm in the presence of ClAlTSPc when the former was embedded in fiber and suspended in a dimethyl sulfoxide solution of the latter. A clear singlet oxygen generation by ClAlTSPc though Förster resonance energy transfer was demonstrated using a singlet oxygen quencher, 1,3-diphenylisobenzofuran. , Original publication is available at http://dx.doi.org/10.1007/s10895-015-1632-z
- Full Text: false
Fluorescence Behaviour of an Aluminium Octacarboxy Phthalocyanine - NaYGdF4:Yb/Er Nanoparticle Conjugate
- Authors: Taylor, Jessica , Litwinski, Christian , Nyokong, Tebello , Antunes, Edith M
- Language: English
- Type: Article
- Identifier: vital:7247 , http://hdl.handle.net/10962/d1020252
- Description: Using a methanol assisted thermal decomposition approach, sphere shaped NaYGdF4:Yb/Er upconversion nanoparticles (UCNPs) were successfully synthesized. The chemical, spectroscopic and fluorescence properties of the UCNPs were fully characterized. Characteristic upconversion fluorescence emissions were produced by the NPs in the green, red and NIR regions and the NPs were also shown to possess paramagnetic properties. The influence of the UCNPs on the spectroscopic and fluorescence properties of an aluminium octacarboxy phthalocyanine AlOCPc was investigated. Covalent conjugation to an AlOCPc resulted in a large blue shift of the phthalocyanine’s Q band, which was accompanied by a decrease in the Pc’s fluorescence lifetime in DMSO. By combining the phthalocyanine and upconversion nanoparticle, we present a system capable of multimodal imaging, using both the upconversion nanoparticle’s and phthalocyanine’s emission, and magnetic resonance imaging (as a result of doping the upconversion nanoparticles with Gd3+ ions). , Original publication is available at http://dx.doi.org/10.1007/s10895-015-1539-8
- Full Text: false
Spectral properties and photophysical behaviour of water soluble cationic Mg(II) and Al(III) phthalocyanines
- Authors: Idowu, Mopelola A , Arslanoglu, Yasin , Nyokong, Tebello
- Language: English
- Type: Article
- Identifier: vital:7277 , http://hdl.handle.net/10962/d1020292
- Description: Peripherally and non-peripherally tetrasubstituted-[(N-methyl-2-pyridylthio)]phthalocyaninato magnesium (II) (5 and 6) and chloro aluminium (III) (7 and 8) tetraiodide have been synthesized and characterized. The photophysical properties of the complexes in dimethyl sulfoxide (DMSO) and aqueous medium in the presence and absence of cremophore EL have been studied. These complexes show high solubility in aqueous medium though they were aggregated. The triplet state quantum yields (FT) and the triplet lifetimes (tT) were found to be higher in DMSO with ΦT ranging from 0.32 to 0.51, while tT ranged from 282 to 622 ms in DMSO, compared to aqueous medium (pH 7.4 buffer) where ΦT ranged from 0.15 to 0.19 and tT from 26 to 35 ms. Addition of cremophore EL in aqueous solution resulted in partial disaggregation and increased photoactivity. The fluorescence lifetimes of the complexes showed strong dependence on their immediate environment. The ionic magnesium(II) and aluminium(III) phthalocyanines strongly bind to bovine serum albumin (BSA). , Original publication is available at http://dx.doi.org/10.2478/s11532-013-0388-z
- Full Text: false