Knowledge management : an evaluation from the users' perspective

Includes bibliographical references.The present study is an analysis of Cap Gemini Ernst and Young's Knowledge Management (KM) System from a user based perspective. The willingness of users to adopt CGEY's KM system was examined, using the five factors identified by Roger's Theory of Diffusion of Innovation. Adoption of CGEY's KM system encompasses the concept of getting users to willingly contribute their own knowledge and use others' and therefore establishing a knowledge sharing culture. In addition to investigating Roger's theory, the user's perspective was used to determine the validity of Pollard's study that identifies four key factors that are critical to the success in establishing a knowledge sharing culture.B.S. (Bachelor of Science

Harnessing the optical properties of gold nanorods: fluorescence enhancement, biosensing and photothermal therapy

In recent years, there has been great interest in the synthesis, characterization, and application of gold nanomaterials, especially gold nanorods. Due to their small size, ease of functionalization, and uniquely tunable optical properties, gold nanorods have potential application in solar cells, sensing, bioimaging, drug delivery, and cancer therapy. Excitation of a gold nanorod localized surface plasmon resonance (LSPR) can result in the enhancement of many photophysical processes such as light absorption, Rayleigh (Mie) scattering, and fluorescence. The presence of a strong electromagnetic field has been observed to enhance spectroscopic molecular signals from fluorophores, Raman-active molecules, and two-photon chromophores bound to or near the metal surface. Additionally, strong light absorption and nonradiative dissipation of absorbed energy allows for the use of gold nanorods in photothermal heating applications. Optical applications such as these may be realized by carefully engineering the size, shape, surface chemistry of gold nanorods. The focus of this dissertation is in exploring how gold nanorod surface properties can be modified for various optical applications. In each chapter, gold nanorods are prepared, the surface coating is modified, and the materials are characterized by a variety of methods. This thesis seeks to demonstrate how these materials may be useful, with a focus on three particular applications: fluorescence enhancement, biosensing and photothermal therapy. Chapter 1 is an introduction to gold nanorods and contains a thesis overview. The unique optical properties, which are the basis for most applications, are discussed. This is followed by a general overview of the possible optical applications of gold nanorods. The history of advancements in gold nanorod synthesis and techniques for surface modification are described. There is a particular focus on the surface modification techniques most often used in this thesis, including thiol functionalization, silica coating and layer-by-layer wrapping of polyelectrolytes. Methods for characterization of gold nanorods, and their surface coatings are described, and the chapter ends with a dissertation overview. Plasmonic nanoparticles can strongly interact with adjacent fluorophores, resulting in plasmon-enhanced fluorescence or fluorescence quenching. Chapter 2 explores how fluorescence behavior is altered near a gold nanorod surface. Fluorescence coupling is dependent upon nanoparticle composition, the distance between the fluorophore and the plasmonic surface, the transition dipole orientation, and the degree of spectral overlap between the fluorophore’s absorbance/emission and the surface plasmon band of the nanoparticles. We examine the distance and plasmon wavelength dependent fluorescence of an infrared dye (“IRDye”) bound to silica-coated gold nanorods. Nanorods with plasmon band maxima ranging from 530 to 850 nm are synthesized and then coated with mesoporous silica shells 11–26 nm thick. IRDye is covalently attached to the nanoparticle surface via a click reaction. Steady-state fluorescence measurements demonstrate plasmon wavelength and silica shell thickness dependent fluorescence emission. Maximum fluorescence intensity, with approximately 10-fold enhancement, is observed with 17 nm shells when the nanorod plasmon maximum is resonant with IRDye absorption. Time-resolved photoluminescence reveals multi-exponential decay and a sharp reduction in fluorescence lifetime with decreasing silica shell thickness, and when the plasmon maximum is closer to IRDye absorption/emission. Control experiments are carried out to confirm that the observed changes in fluorescence are due to plasmonic interactions, not simply surface attachment. There is no change in fluorescence intensity or lifetime when IRDye is bound to mesoporous silica nanoparticles. In addition, IRDye loading is limited to maintain a distance between dye molecules on the surface to more than 9 nm, well above the Förster radius. This assures minimal dye–dye interactions on the surface of the nanoparticles. The interface between nanoparticles and bacterial surfaces is of great interest for applications in nanomedicine and food safety. In Chapter 3, we investigate how nanoparticles might interact with bacteria by monitoring the binding of bacterial lipopolysaccharides to gold nanorods. We demonstrate that interactions between gold nanorods and lipopolysaccharides are governed by the nanoparticle surface coating. Polymer-coated gold nanorod substrates are exposed to lipopolysaccharides extracted from Pseudomonas aeruginosa, Salmonella enterica and Escherichia coli, and attachment is monitored using localized surface plasmon resonance refractometric sensing. The number of lipopolysaccharide molecules attached per nanorod is calculated from the shift in the plasmon maximum, which results from the change in refractive index after analyte binding. Colloidal gold nanorods in water are also incubated with lipopolysaccharides to demonstrate the effect of lipopolysaccharide concentration on plasmon shift, ζ-potential, and association constant. Both gold nanorod surface charge and surface chemistry affect gold nanorod–lipopolysaccharide interactions. In general, anionic lipopolysaccharides are found to attach more effectively to cationic gold nanorods than to neutral or anionic gold nanorods. Some variation in lipopolysaccharide attachment is also observed between the three strains studied, demonstrating the potential complexity of bacteria–nanoparticle interactions. In recent years, there has been a great deal of interest in the preparation and application of nanoparticles for cancer therapy. Chapter 4 reviews the progress in thermal cancer treatments using gold nanoparticles. Gold nanoparticles are especially suited to thermal destruction of cancer due to their ease of surface functionalization and photothermal heating ability. We begin with an introduction to the properties of gold nanoparticles and heat-generating mechanisms which have been established. The pioneering work in photothermal therapy is discussed along with the effects of photothermal heating on cells in vitro. Additionally, radiofrequency-mediated thermal therapy is reviewed. We focus the discussion on the developments and progress in nanoparticle design for photothermal cancer therapy since 2010. This includes in vitro and in vivo studies, and the recent progression of gold nanoparticle photothermal therapy toward clinical cancer treatment. The chapter concludes with a perspective on the prospects of commercial application of photothermal-mediated cancer therapy with gold nanoparticles Chapter 5 expands the range of photothermal therapy applications to inactivation of vegetative cells and endospores of the bacterium Geobacillus stearothermophilus. Gold nanorods are prepared and characterized and are coated with four different neutral or charged polymers to investigate the impact of surface charge on cell attachment and inactivation. The effects of gold nanorod exposure and photothermal heating using a 785 nm laser on colony growth of spores and vegetative cells reveal greater reductions in colony formation with charged nanorods. Additionally, spore morphology is examined before and after treatment. There are small changes in morphology observed as increasing area per spore and decreased spore aspect ratio which might be correlated with inactivation. Although the inactivation of endospores is not as great as traditional sterilization techniques, these results demonstrate that there is potential in the application of photothermal heating with gold nanorods to inactivate heat-resistant bacterial endospores. In Chapter 6 we consider how gold nanorod surface chemistry may be modified by silica coating and silane functionalization to maintain optical stability and therefore increase the effectiveness of gold nanorods in optical applications. Heating in an oven to 150°C, and charging due to electron beam exposure cause shortening and widening of gold nanorods and result in decreased in aspect ratio. However, these changes in morphology and optical properties are greatly reduced by silica coating and silane functionalization. Pulsed laser irradiation also is found to alter gold nanorod optical properties, and interesting changes in gold nanorod morphology are observed. Together, these results suggest that silica coating and silane functionalization improve the shape stability of gold nanorods and therefore may help to preserve the optical properties, especially compared to CTAB gold nanorods. The increased prevalence of functionalized nanomaterials in a range of applications will inevitably lead to nanomaterial contamination of soil and groundwater. Chapter 7 moves past nanotechnology applications to consider the environmental fate of gold nanomaterials. We investigate how nanoparticle shape and surface chemistry influences their stability and transport within environmental systems. A library of spherical and rod-shaped gold nanoparticles is prepared with different surface chemistries. Nanoparticle stability against aggregation in simulated groundwater is investigated. The stability of gold nanoparticle probes in simulated groundwater depends on both the surface charge imparted by the capping agent, and the nature of the interaction between the nanoparticle surface and the capping agent. However, in the presence of natural organic matter, gold nanoparticles are found to form heteroaggregates, regardless of the initial surface coating. In addition, nanoparticle retention in columns of soil and alginate is quantified. The surface charge and capping agent interaction also influence retention of functionalized nanoparticles. Negatively-charged gold nanoparticles are only weakly retained in soil and alginate, and hence, are potentially much more mobile in environmental matrices than nanoparticles carrying positive surface charges. Together, these data suggest that the environmental fate of nanoparticles is strongly influenced by their surface chemistry, as well as core material and size

Perceptions of French and Creole Among First-Generation Adult Haitian English Language Learners

Context: Due to a unique combination of factors, outdoor athletes in the Southeastern United States are at high risk of lightning deaths and injuries. Lightning detection methods are available to minimize lightning strike victims. Objective: Becoming aware of the risk factors that predispose athletes to lightning strikes and determining the most reliable detection method against hazardous weather will enable Certified Athletic Trainers to develop protocols that protect athletes from injury. Data Sources: A comprehensive literature review of Medline and Pubmed using key words: lightning, lightning risk factors, lightning safety, lightning detection, and athletic trainers and lightning was completed. Data Synthesis: Factors predisposing athletes to lighting death or injury include: time of year, time of day, the athlete’s age, geographical location, physical location, sex, perspiration level, and lack of education and preparedness by athletes and staff. Although handheld lightning detectors have become widely accessible to detect lightning strikes, their performance has not been independently or objectively confirmed. There is evidence that these detectors inaccurately detect strike locations by recording false strikes and not recording actual strikes. Conclusions: Lightning education and preparation are two factors that can be controlled. Measures need to be taken by Certified Athletic Trainers to ensure the safety of athletes during outdoor athletics. It is critical for athletic trainers and supervising staff members to become fully aware of the risks of lightning strikes in order to most effectively protect everyone under their supervision. Even though lightning detectors have been manufactured in an attempt to minimize death and injuries due to lightning strikes, none of the detectors have been proven to be 100% effective. Educating coaches, athletes, and parents on the risks of lightning and the detection methods available, while implementing an emergency action plan for lightning safety, is crucial to ensure the well being of the student-athlete population

Kinetic Characterization and Phosphoregulation of the Francisella tularensis 1-Deoxy-D-Xylulose 5-Phosphate Reductoisomerase (MEP Synthase)

Deliberate and natural outbreaks of infectious disease underscore the necessity of effective vaccines and antimicrobial/antiviral therapeutics. The prevalence of antibiotic resistant strains and the ease by which antibiotic resistant bacteria can be intentionally engineered further highlights the need for continued development of novel antibiotics against new bacterial targets. Isoprenes are a class of molecules fundamentally involved in a variety of crucial biological functions. Mammalian cells utilize the mevalonic acid pathway for isoprene biosynthesis, whereas many bacteria utilize the methylerythritol phosphate (MEP) pathway, making the latter an attractive target for antibiotic development. In this report we describe the cloning and characterization of Francisella tularensis MEP synthase, a MEP pathway enzyme and potential target for antibiotic development. In vitro growth-inhibition assays using fosmidomycin, an inhibitor of MEP synthase, illustrates the effectiveness of MEP pathway inhibition with F. tularensis. To facilitate drug development, F. tularensis MEP synthase was cloned, expressed, purified, and characterized. Enzyme assays produced apparent kinetic constants (KMDXP = 104 µM, KMNADPH = 13 µM, kcatDXP = 2 s−1, kcatNADPH = 1.3 s−1), an IC50 for fosmidomycin of 247 nM, and a Ki for fosmidomycin of 99 nM. The enzyme exhibits a preference for Mg+2 as a divalent cation. Titanium dioxide chromatography-tandem mass spectrometry identified Ser177 as a site of phosphorylation. S177D and S177E site-directed mutants are inactive, suggesting a mechanism for post-translational control of metabolic flux through the F. tularensis MEP pathway. Overall, our study suggests that MEP synthase is an excellent target for the development of novel antibiotics against F. tularensis

q-exponential, Weibull, and q-Weibull distributions: an empirical analysis

In a comparative study, the q-exponential and Weibull distributions are employed to investigate frequency distributions of basketball baskets, cyclone victims, brand-name drugs by retail sales, and highway length. In order to analyze the intermediate cases, a distribution, the q-Weibull one, which interpolates the q-exponential and Weibull ones, is introduced. It is verified that the basketball baskets distribution is well described by a q-exponential, whereas the cyclone victims and brand-name drugs by retail sales ones are better adjusted by a Weibull distribution. On the other hand, for highway length the q-exponential and Weibull distributions do not give satisfactory adjustment, being necessary to employ the q-Weibull distribution. Furthermore, the introduction of this interpolating distribution gives an illumination from the point of view of the stretched exponential against inverse power law (q-exponential with q > 1) controversy.Comment: 6 pages, Latex. To appear in Physica

Time-Resolved 3D cardiopulmonary MRI reconstruction using spatial transformer network

The accurate visualization and assessment of the complex cardiac and pulmonary structures in 3D is critical for the diagnosis and treatment of cardiovascular and respiratory disorders. Conventional 3D cardiac magnetic resonance imaging (MRI) techniques suffer from long acquisition times, motion artifacts, and limited spatiotemporal resolution. This study proposes a novel time-resolved 3D cardiopulmonary MRI reconstruction method based on spatial transformer networks (STNs) to reconstruct the 3D cardiopulmonary MRI acquired using 3D center-out radial ultra-short echo time (UTE) sequences. The proposed reconstruction method employed an STN-based deep learning framework, which used a combination of data-processing, grid generator, and sampler. The reconstructed 3D images were compared against the start-of-the-art time-resolved reconstruction method. The results showed that the proposed time-resolved 3D cardiopulmonary MRI reconstruction using STNs offers a robust and efficient approach to obtain high-quality images. This method effectively overcomes the limitations of conventional 3D cardiac MRI techniques and has the potential to improve the diagnosis and treatment planning of cardiopulmonary disorders

Gold nanoparticle-based colorimetric platform technology as rapid and efficient bacterial pathogens detection method from various sources

Rapid, sensitive, and reliable bacterial pathogens detection is a chief requirement. The gold nanoparticles (AuNPs) have numerous applications such as in the detection of biomolecules for their high surface to volume ratio and unique optical property facilitating development of highly efficient AuNPs-based bio-sensing tools. Although various molecular detection methods, such as PCR, real-time PCR, and loop-mediated isothermal amplification are sensitive and convenient, these techniques need elaborate work and require special skills to increase their specificity. Smartly fabricated gold nanoparticle (GNPs) play a role as probes for selective detection of pathogens. The AuNPs-based colorimetric methods have become applicable for rapid, simple, reliable and high-efficient, sensitive, inexpensive, and easy detection of the DNA, RNA, and protein biomolecules. Colorimetric detection using AuNPs has been used for rapid and high precision and multiplex detection of a large number and of bacterial pathogens. AuNPs act in functionalized and unfunctionalized ways. AuNPs-based colorimetric methods have incredible advantages compared with many other bacterial detection methods. In spite of many molecular techniques, AuNPs-based colorimetric methods do not require additional devices, fabrication cost, signal processing and interpretation complexities, and costly and complex instruments. This simple and rapid method is suitable, especially in low-income areas and for large number of samples analysis. In this review, applications of AuNPs and AuNPs-based colorimetric methods for bacterial pathogens detection have been overviewe

Plasmon-promoted electrochemical oxygen evolution catalysis from gold decorated MnO2 nanosheets under green light

The oxygen evolution reaction (OER) is of great importance for renewable energy conversion and storage, however, the intrinsic process is sluggish and suffers from severe efficiency loss as well as large over-potentials. In this work, with the introduction of the plasmonic effects by design of the Au-MnO2 hybrid catalysts, we demonstrate that this photophysical phenomenon could largely promote the confinement of the outer electrons of Mn cations by plasmonic “hot holes” generated on gold surface. These “hot holes” work as the effective electron trapper to form the active Mnn+ species which could provide active sites to extract electrons from OH- and eventually facilitate the electrochemical OER catalysis under low laser power. By tuning the laser intensity from 100 to 200 mW, the over-potential is decreased from 0.38 to 0.32 V, which is comparable to IrO2 and RuO2 catalysts. These findings may provide insights into activation of plasmon-promoted electrocatalysis under low power laser irradiation/treatment and the design of novel composite electrocatalysts

Polylysine-grafted Au144 nanoclusters: birth and growth of a healthy surface-plasmon-resonance-like band

Poly(amino acid)-coated gold nanoparticles hold promise in biomedical applications, particularly because they combine the unique physicochemical properties of the gold core, excellent biocompatibility, and easy functionalization of the poly(amino acid)-capping shell. Here we report a novel method for the preparation of robust hybrid core–shell nanosystems consisting of a Au144 cluster and a densely grafted polylysine layer. Linear polylysine chains were grown by direct N-carboxyanhydride (NCA) polymerization onto ligands capping the gold nanocluster. The density of the polylysine chains and the thickness of the polymer layer strongly depend on the amount and concentration of the NCA monomer and the initiator. The optical spectra of the so-obtained core–shell nanosystems show a strong surface plasmon resonance (SPR)-like band at 531 nm. In fact, despite maintenance of the gold cluster size and the absence of interparticle aggregation, the polylysine-capped clusters behave as if they have a diameter nearly 4 times larger. To the best of our knowledge, this is the first observation of the growth of a fully developed, very stable SPR-like band for a gold nanocluster of such dimensions. The robust polylysine protective shell makes the nanoparticles very stable under conditions of chemical etching, in the presence of glutathione, and at different pH values, without gold core deshielding or alteration of the SPR-like band. This polymerization method can conceivably be extended to prepare core–shell nanosystems based on other mono- or co-poly(amino acids)

Nanotechnology advances towards development of targeted-treatment for obesity

Obesity through its association with type 2 diabetes (T2D), cancer and cardiovascular diseases (CVDs), poses a serious health threat, as these diseases contribute to high mortality rates. Pharmacotherapy alone or in combination with either lifestyle modifcation or surgery, is reliable in maintaining a healthy body weight, and preventing progression to obesity-induced diseases. However, the anti-obesity drugs are limited by non-specifcity and unsustainable weight loss efects. As such, novel and improved approaches for treatment of obesity are urgently needed. Nanotechnology-based therapies are investigated as an alternative strategy that can treat obesity and be able to overcome the drawbacks associated with conventional therapies. The review presents three nanotechnology-based anti-obesity strategies that target the white adipose tissues (WATs) and its vasculature for the reversal of obesity. These include inhibition of angiogenesis in the WATs, transformation of WATs to brown adipose tissues (BATs), and photothermal lipolysis of WATs. Compared to conventional therapy, the targeted-nanosystems have high tolerability, reduced side efects, and enhanced efcacy. These efects are reproducible using various nanocarriers (liposomes, polymeric and gold nanoparticles), thus providing a proof of concept that targeted nanotherapy can be a feasible strategy that can combat obesity and prevent its comorbiditie