Extraction and Quantification of Atrazine

Undergraduate Basi

Screening for hydroxynitrile lyase activity in non-commercialised plants

AbstractHydroxynitrile lyases are used for the synthesis of enantiomerically pure cyanohydrins which are of great importance in the pharmaceutical and fine chemical industries. In this study, the hydroxynitrile lyase activity of 100 plants from 40 families was investigated, first by screening for cyanogenic activity, followed by a hydroxynitrile lyase activity assay. Of the 100 plants, four were found to be cyanogenic and exhibited specific hydroxynitrile lyase activity: Adenia sp. (0.44U/mg), Adenia firingalavensis (2.88U/mg), Adenia fruticosa (1.99U/mg) and, Adenia pechuelii (2.35U/mg), all from the family Passifloraceae. This is the first report of hydroxynitrile lyase activity in these plants

The Structural and Cultural Constraints on Policy Implementation : a case study on further education and training Colleges in South Africa

In its first decade of democracy the South African government embarked on radical reforms to the apartheid education system. One such set of reforms concerned the restructuring of the further education and training (FET) college sector. The implementation plan for the restructuring of the FET college sector, entitled Reform of South Africa’s Technical Colleges (Department of Education, 2001), was released in September 2001. The reorganisation of the FET college sector brought with it the prospect of meeting the objectives of the country’s Human Resource Development Strategy (Department of Education, 2001). Colleges would be transformed so that they offered learners the “high-quality, lifelong learning opportunities that are essential to social development and economic competitiveness in a rapidly changing world” (Department of Education, 2001:5). The study has its origins in a deceptively simple research question: What are the organisational and cultural influences and constraints on policy implementation? Much has been written about why policies fail to be implemented as planned (McLaughlin 1987; Guiacquinta, 1994). Based on the extensive data generated in this research I found explanatory power in a conceptual framework that uses the dual lenses of restructuring, focusing on “changing the use of time, space, roles and relationships to improve learning” (Fink&Stoll, 1998:308); and reculturing, which focuses on “the process of developing new values, beliefs and norms” (Fullan, 1996:420). The new government policy for FET colleges proposed a dramatic re-organisation of the sector through mergers in order to position these institutions so as to meet the socio-economic and human resource needs of a transforming society in line with global trends. Yet, an analysis of the sector revealed system-level problems relating to the structure and culture of the FET colleges that would undermine the implementation of the new policy. The comparative case study method was used to conduct this research on three technical colleges – two state-aided and one state college – as the “cases” under investigation. Data was collected over a one-year period using a wide variety of data collection methods including in-depth interviews (both individual and focus group sessions), document analysis, the review of minutes of meetings and other communiqués, selected photographs and structured questionnaires. The first major finding of this study is that the restructuring of the FET colleges through mergers was constrained by structural or the organisational inefficiencies in the system, that is, the lack or absence of the structures required for effective implementation of policy. The second major finding of this study is that the restructuring process underestimated the depth and resilience of the FET college culture, and that this institutional culture militated against effective implementation. In other words, there was no strategy for reculturing these institutions. This research further demonstrates the consequences of attempted restructuring without reculturing and the implications of not taking into account implementation matters involving institutional culture, values, behaviour and working styles. Successful change has more to do with the professional values, beliefs and assumptions held by implementers than with the voluntary adoption of the reform, irrespective of whether it is mandated at the national or provincial levels. Implementers choose practices and changes that fit best with their pre-existing beliefs and which are consistent with the organisation’s culture. Furthermore, the insights gained from this study that structure and culture are inextricably linked have both practical and theoretical significance. The study not only offers insight into the reorganisation of the FET colleges in South Africa, but also serves to extend our understanding of the importance of culture and structure as two neglected dimensions of systemic reform. In this study I highlighted several issues that could serve as a springboard for future research into this neglected sector (FET colleges) of the education and training system: · longitudinal rather than snapshot studies of institutional cultures and their unfolding effects on college restructuring; · empirical and conceptual accounts of college cultures that examine the impact of micro-political activity on the change trajectory; and · studies on how college systems change or restructure as opposed to individual colleges. In sum this research found that there were several structural (capacity, resource, leadership, support, communication, planning and advocacy) and cultural (beliefs, values, assumptions, understanding and practices) factors that constrained policy implementation. The study further argues that restructuring without reculturing encourages symbolic rather than substantive change. The thesis concludes that the restructuring (mergers) resulted in a fragmented, rather than a coordinated, FET system.Thesis (PhD (Education Management and Policy Studies))--University of Pretoria, 2006.Education Management and Policy Studiesunrestricte

Current Advances in Immune Checkpoint Therapy

Although immune checkpoint inhibitors (ICIs) have shown survival benefits for patients with metastatic cancers, some challenges have been under intense study in recent years. The most critical challenges include the side effects and the emergence of resistance. Potential opportunities exist to develop personalized immune checkpoint inhibitor therapy based on biomarker discovery. Combinational therapy involving immune checkpoint inhibitors and other forms of anticancer therapies has varied success. This chapter reviews drugs currently undergoing Phase III clinical trials and others that are FDA-approved. We take a critical look at the combinational strategies and address the ever-present challenge of resistance. Moreover, we review and evaluate the discovery of biomarkers and assess prospects for personalized immune checkpoint therapy

Improving the normalization of complex interventions: measure development based on normalization process theory (NoMAD): study protocol

<b>Background</b> Understanding implementation processes is key to ensuring that complex interventions in healthcare are taken up in practice and thus maximize intended benefits for service provision and (ultimately) care to patients. Normalization Process Theory (NPT) provides a framework for understanding how a new intervention becomes part of normal practice. This study aims to develop and validate simple generic tools derived from NPT, to be used to improve the implementation of complex healthcare interventions.<p></p> <b>Objectives</b> The objectives of this study are to: develop a set of NPT-based measures and formatively evaluate their use for identifying implementation problems and monitoring progress; conduct preliminary evaluation of these measures across a range of interventions and contexts, and identify factors that affect this process; explore the utility of these measures for predicting outcomes; and develop an online users’ manual for the measures.<p></p> <b>Methods</b> A combination of qualitative (workshops, item development, user feedback, cognitive interviews) and quantitative (survey) methods will be used to develop NPT measures, and test the utility of the measures in six healthcare intervention settings.<p></p> <b>Discussion</b> The measures developed in the study will be available for use by those involved in planning, implementing, and evaluating complex interventions in healthcare and have the potential to enhance the chances of their implementation, leading to sustained changes in working practices

Lipid tethering of breast tumor cells enables real-time imaging of free-floating cell dynamics and drug response

Funding for Open Access provided by the UMD Libraries' Open Access Publishing Fund.Free-floating tumor cells located in the blood of cancer patients, known as circulating tumor cells (CTCs), have become key targets for studying metastasis. However, effective strategies to study the free-floating behavior of tumor cells in vitro have been a major barrier limiting the understanding of the functional properties of CTCs. Upon extracellular-matrix (ECM) detachment, breast tumor cells form tubulin-based protrusions known as microtentacles (McTNs) that play a role in the aggregation and re-attachment of tumor cells to increase their metastatic efficiency. In this study, we have designed a strategy to spatially immobilize ECM-detached tumor cells while maintaining their free-floating character. We use polyelectrolyte multilayers deposited on microfluidic substrates to prevent tumor cell adhesion and the addition of lipid moieties to tether tumor cells to these surfaces through interactions with the cell membranes. This coating remains optically clear, allowing capture of high-resolution images and videos of McTNs on viable free-floating cells. In addition, we show that tethering allows for the real-time analysis of McTN dynamics on individual tumor cells and in response to tubulin-targeting drugs. The ability to image detached tumor cells can vastly enhance our understanding of CTCs under conditions that better recapitulate the microenvironments they encounter during metastasis

Assembly of Silver Nanoparticles into Hollow Spheres Using Eu(III) Compound based on Trifluorothenoyl-Acetone

The preparation of luminescent silver hollow spheres using Eu(III) compound based on trifluorothenoyl-acetone is described. The structure and size of silver hollow spheres were determined by TEM images. The result shows the formation of hollow structure and average size of the silver hollow spheres (0.9 μm). The silver hollow spheres were further characterized by UV absorption spectrum, SNOM and SEM images, suggesting them to be formed by self-assemble of some isolated silver nanoparticles. The luminescent properties of them were also investigated and they are shown to be high emission strength; moreover, they offer the distinct advantage of a lower packing density compared with other commercial luminescent products

Sinusoidal voltage protocols for rapid characterisation of ion channel kinetics

Understanding the roles of ion currents is crucial to predict the action of pharmaceuticals and mutations in different scenarios, and thereby to guide clinical interventions in the heart, brain and other electrophysiological systems. Our ability to predict how ion currents contribute to cellular electrophysiology is in turn critically dependent on our characterisation of ion channel kinetics - the voltage-dependent rates of transition between open, closed and inactivated channel states. We present a new method for rapidly exploring and characterising ion channel kinetics, applying it to the hERG potassium channel as an example, with the aim of generating a quantitatively predictive representation of the ion current. We fit a mathematical model to currents evoked by a novel 8 second sinusoidal voltage clamp in CHO cells over-expressing hERG1a. The model is then used to predict over 5 minutes of recordings in the same cell in response to further protocols: a series of traditional square step voltage clamps, and also a novel voltage clamp comprised of a collection of physiologically-relevant action potentials. We demonstrate that we can make predictive cell-specific models that outperform the use of averaged data from a number of different cells, and thereby examine which changes in gating are responsible for cell-cell variability in current kinetics. Our technique allows rapid collection of consistent and high quality data, from single cells, and produces more predictive mathematical ion channel models than traditional approaches

Effects of the Template Composition and Coating on the Photoluminescence Properties of ZnS:Mn Nanoparticles

Mn-doped ZnS nanocrystals based on low dopant concentrations (0–2%) and coated with a shell of Zn(OH)2 have been prepared via soft template and precipitation reaction. The results indicate that the ZnS:Mn nanocrystal is cubic zinc blende structure and its diameter is 3.02 nm as demonstrated by XRD. Measured by TEM, the morphology of nanocrystals is a spherical shape, and their particle size (3–5 nm) is similar to that of XRD results. Photoluminescence spectra under ultraviolet region shows that the volume ratio of alcohol to water in the template has a great effect on the luminescence properties of ZnS:Mn particles. Compared with unpassivated ZnS:Mn nanocrystals, ZnS:Mn/Zn(OH)2 core/shell nanocrystal exhibits much improved luminescence and higher absolute quantum efficiency. Meanwhile, we simply explore the formation mechanism of ZnS:Mn nanocrystals in alcohol and water system and analyze the reason why alcohol and water cluster structures can affect the luminescent properties of nanoparticle