Community care worker perceptions of their roles in tuberculosis care and their information needs:

Community care workers (CCWs) inhabit a central role in the management of tuberculosis (TB) patients in South Africa. CCWs attend training courses, but training is not standardised at either the national or provincial level. To explore perceptions of CCWs of their role in TB care and TB information needs

An illustrated booklet for reinforcing community healthworker knowledge of tuberculosis and facilitating patient counselling

Community health workers (CHWs) have facilitated the move to decentralise tuberculosis (TB) management, but lack access to information appropriate both for personal use and in patient interaction and education.To explore the impact of a pictorial-based TB booklet on reinforcing CHW knowledge and facilitating patient counselling. This study was conducted in local primary health care clinics and the Hospice in Grahamstown, Eastern Cape Province in South Africa.Quantitative and qualitative methods were used. A simple, 17-page, A5 booklet containing pictograms and simple text was designed in collaboration with CHWs who advised on preferred content. Its influence on knowledge was assessed in 31 CHWs using a 17-item questionnaire in a before-and-after study. The experiences of CHWs using the booklet were qualitatively explored using focus group discussions (FGD) and semi-structured interviews

Connecting Planetary Composition with Formation

The rapid advances in observations of the different populations of exoplanets, the characterization of their host stars and the links to the properties of their planetary systems, the detailed studies of protoplanetary disks, and the experimental study of the interiors and composition of the massive planets in our solar system provide a firm basis for the next big question in planet formation theory. How do the elemental and chemical compositions of planets connect with their formation? The answer to this requires that the various pieces of planet formation theory be linked together in an end-to-end picture that is capable of addressing these large data sets. In this review, we discuss the critical elements of such a picture and how they affect the chemical and elemental make up of forming planets. Important issues here include the initial state of forming and evolving disks, chemical and dust processes within them, the migration of planets and the importance of planet traps, the nature of angular momentum transport processes involving turbulence and/or MHD disk winds, planet formation theory, and advanced treatments of disk astrochemistry. All of these issues affect, and are affected by the chemistry of disks which is driven by X-ray ionization of the host stars. We discuss how these processes lead to a coherent end-to-end model and how this may address the basic question.Comment: Invited review, accepted for publication in the 'Handbook of Exoplanets', eds. H.J. Deeg and J.A. Belmonte, Springer (2018). 46 pages, 10 figure

Reducing the environmental impact of surgery on a global scale: systematic review and co-prioritization with healthcare workers in 132 countries

Background Healthcare cannot achieve net-zero carbon without addressing operating theatres. The aim of this study was to prioritize feasible interventions to reduce the environmental impact of operating theatres. Methods This study adopted a four-phase Delphi consensus co-prioritization methodology. In phase 1, a systematic review of published interventions and global consultation of perioperative healthcare professionals were used to longlist interventions. In phase 2, iterative thematic analysis consolidated comparable interventions into a shortlist. In phase 3, the shortlist was co-prioritized based on patient and clinician views on acceptability, feasibility, and safety. In phase 4, ranked lists of interventions were presented by their relevance to high-income countries and low–middle-income countries. Results In phase 1, 43 interventions were identified, which had low uptake in practice according to 3042 professionals globally. In phase 2, a shortlist of 15 intervention domains was generated. In phase 3, interventions were deemed acceptable for more than 90 per cent of patients except for reducing general anaesthesia (84 per cent) and re-sterilization of ‘single-use’ consumables (86 per cent). In phase 4, the top three shortlisted interventions for high-income countries were: introducing recycling; reducing use of anaesthetic gases; and appropriate clinical waste processing. In phase 4, the top three shortlisted interventions for low–middle-income countries were: introducing reusable surgical devices; reducing use of consumables; and reducing the use of general anaesthesia. Conclusion This is a step toward environmentally sustainable operating environments with actionable interventions applicable to both high– and low–middle–income countries

Reducing the environmental impact of surgery on a global scale: systematic review and co-prioritization with healthcare workers in 132 countries

Abstract Background Healthcare cannot achieve net-zero carbon without addressing operating theatres. The aim of this study was to prioritize feasible interventions to reduce the environmental impact of operating theatres. Methods This study adopted a four-phase Delphi consensus co-prioritization methodology. In phase 1, a systematic review of published interventions and global consultation of perioperative healthcare professionals were used to longlist interventions. In phase 2, iterative thematic analysis consolidated comparable interventions into a shortlist. In phase 3, the shortlist was co-prioritized based on patient and clinician views on acceptability, feasibility, and safety. In phase 4, ranked lists of interventions were presented by their relevance to high-income countries and low–middle-income countries. Results In phase 1, 43 interventions were identified, which had low uptake in practice according to 3042 professionals globally. In phase 2, a shortlist of 15 intervention domains was generated. In phase 3, interventions were deemed acceptable for more than 90 per cent of patients except for reducing general anaesthesia (84 per cent) and re-sterilization of ‘single-use’ consumables (86 per cent). In phase 4, the top three shortlisted interventions for high-income countries were: introducing recycling; reducing use of anaesthetic gases; and appropriate clinical waste processing. In phase 4, the top three shortlisted interventions for low–middle-income countries were: introducing reusable surgical devices; reducing use of consumables; and reducing the use of general anaesthesia. Conclusion This is a step toward environmentally sustainable operating environments with actionable interventions applicable to both high– and low–middle–income countries

NONLINEAR OPTICAL PROCESSES IN MOLECULAR SYSTEMS AT THE INTERFACE WITH METAL NANOSTRUCTURES

Surface plasmon excitations, i.e. collective oscillations of the conduction electrons, strongly influence the optical properties of metal nanostructures. Furthermore, under resonance conditions, a giant local electromagnetic field develops on the nanostructure surface. By controlling the size and shape of the nanostructures, it is possible to control the surface plasmon resonance frequency and so the frequency at which the local field will be amplified. If a molecule is located at the interface with metal nanostructures, its optical properties will be affected by the local field and can be enhanced or suppressed by the metal. Here, the effect on the optical properties of molecules due to the interaction with metal nanostructures is investigated by different techniques. Emphasis is placed on the synthesis and the study of the nonlinear properties of nude and functionalized gold nanoshells (NSs). Different shape gold nanoparticles are synthesized: spherical particles in water and in toluene, rod like particles in water subsequently transferred in organic solvents, core-shells in water. Gold nanostructures have been functionalized with spiropyran, PEP-C3-SH and PEP-C12-SH (two heterocyclic dyes), Rhodamine B. Fluorescence decay times for PEP-C3-SH and PEP-C12-SH free and bound to nanorods (NRs) have been measured to study the interaction between the dye and the nanostructure and to evaluate the effects of the chain length. The PEP moieties present a two exponential decay times: a short one of 6.2 ± 0.5 ns and a long one of 61 ± 2 ns. When the dye is bound to NRs, the interaction between the molecules and the nanoparticles provoked a change in the PEP dynamics. Both PEP-C3 and PEP-C12 bound to NRs, decay faster, indicating quenching of fluorescence. Nanoshells functionalized with Rhodamine B have been characterized with Pump and Probe technique. The dye clearly modified the dynamics of naked NSs and shortened the electron-phonon time decay from 4.9 ps (naked NSs) to 3.7 ps (RhB-NSs) introducing an additional channel by which hot electrons can decay. SERS measurements of NSs, deposited on glass substrates, covered by benzenethiol were performed. Incomplete shells with sharp tips may turn out to be quite interesting for SERS analysis due to the strong local field that take place at tip apexes. Enhancement of the Raman signal has been clearly observed because the concentration of benzenethiol is too low to give Raman signal except in case of strong enhancement field effects. Z-scan measurements, with fs laser pulses, were performed at 20 and 200 Hz and at different energy to study the nonlinear response of naked NRs and NSs. Both nanostructures behaved like saturable absorber and reshaped during laser pulse illumination. NSs z-scan data, fitted with Sheik-Bahae model, yielded an effective value of the non linear absorption coefficient β = (–1.1 ÷ –9.6) X 10-11 cmW-1 dependent on the pulse energy and repetition rate. The absolute value of the nonlinear absorption coefficient increased both with energy and pulse repetition rate. The effect of increasing the repetition rate is likely related to thermal effects, also confirmed by an increase of the beam waist radius used for fitting the z-scan data. The dependence on the energy, instead, indicated that the process is not a third order phenomenon, but higher order contributions should be taken into account. Together with the plasmonic effects, the NSs deposition onto a transparent electrode potentially allows for improved efficiency both for light collection and charge collection. With this motivation, work function measurements on NSs deposited ITO substrates have been performed by the Kelvin probe method. They showed that by selectively choosing the shell thickness, ITO pre-functionalization and nanoparticle coverage, it is possible to fine-tune the WF of the transparent electrode within the range of 3.9 – 4.4 eV.L’eccitazione dei plasmoni di superficie, cioè dell’oscillazione collettiva degli elettroni di conduzione, influenza fortemente le proprietà ottiche delle nanostrutture metalliche. Inoltre, in condizioni di risonanza, si sviluppa, sulla superficie della nanostruttura, un fortissimo campo elettrico localizzato. Controllando le dimensioni e la forma delle nanostrutture, è possibile controllare la frequenza di risonanza del plasmone superficiale e, di conseguenza, la frequenza alla quale il campo elettrico locale verrà amplificato. Se una molecola è posizionata all’interfaccia con la nanostruttura metallica, le sue proprietà ottiche risentiranno del campo locale e potranno essere amplificate o ridotte dal metallo. In questo lavoro di tesi, sono stati studiati, con diverse tecniche, gli effetti, sulle proprietà ottiche di molecole, dell’interazione con nanostrutture metalliche. In particolare, ci si è concentrati sulla sintesi e sullo studio delle proprietà non lineari di nanoshell (NSs) nude e funzionalizzate. Sono state sintetizzate nanoparticelle di oro di forma diversa: particelle sferiche in acqua e toluene, a forma di rod in acqua (successivamente trasferite in solventi organici), core-shell in acqua. Le nanostrutture d’oro sono state funzionalizzate con spiropirani, PEP-C3-SH e PEP-C12-SH (due molecole eterocicliche), Rodamina B. I tempi di decadimento di fluorescenza per PEP-C3-SH e PEP-C12-SH liberi e legati alle nanorods (NRs) sono stati misurati per studiare l’interazione tra il colorante e la nanostruttura e per valutare gli effetti della diversa lunghezza della catena alchilica. Il colorante, indipendentemente dalla lunghezza della catena, presenta un decadimento biesponenziale con un tempo breve di 6.2 ± 0.5 ns e uno lungo di 61 ± 2 ns. In seguito alla funzionalizzazione, l’interazione tra la molecola e le NRs provoca un cambiamento nella dinamica di decadimento del PEP. Sia il PEP-C3 che il PEP-C12 legati alle NRs, decadono più rapidamente, indicando un’attenuazione della fluorescenza. Le nanoshell funzionalizzate con la Rodamina B sono state caratterizzate con la tecnica Pump and Probe. Il colorante modifica la dinamica delle NSs e riduce il tempo di decadimento dell’accoppiamente elettrone-fonone da 4.9 ps (NS nude) a 3.7 ps (RhB-NSs), introducendo un canale addizionale attraverso cui gli elettroni caldi possono decadere. Sono state effettuate delle misure SERS su benzentiolo attaccato a nanoshell, depositate su substrati di vetro. Shell incompleti caratterizzati da punte acuminate possono risultare molto interessanti per la Spettroscopia SERS per i forti campi locali che si sviluppano sulle punte. Un aumento del segnale Raman è stato chiaramente osservato, dato che la concentrazione di benzentiolo era troppo bassa per dare segnale Raman eccetto in caso di effetti di campo locale. Sono state effettuare misure Z-scan con impulsi di durata di centinaia di femtosecondi, a frequenza di ripetizione di 20 e 200 Hz e a diverse energie, per studiare la risposta non lineare di NRs e NSs non funzionalizzate. Entrambe le nanostrutture si comportano come assorbitori saturabili e subiscono delle modifiche morfologiche per effetto dell’illuminazione con impulsi laser. I dati z-scan per le nanoshell, fittati con il modello Sheik-Bahae, producono un valore effettivo del coefficiente di assorbimento non lineare β = (–1.1 ÷ –9.6) X 10-11 cmW-1 che dipende sia dall’energia dell’impulso che dalla frequenza di ripetizione. Il valore assoluto del coefficiente di assorbimento non lineare aumenta sia con l’energia che con la frequenza di ripetizione. L’aumento con la frequenza di ripetizione è dovuto a effetti termici, confermati anche da un aumento del raggio del beam waist usato per fittare i dati z-scan. Invece, la dipendenza dall’energia indica che il processo non è un fenomeno al terzo ordine ma si deve tenere conto di contributi di ordine superiore. Insieme agli effetti plasmonici, le nanoshell depositate su elettrodi trasparenti, come l’ITO (Indium Tin Oxide), potrebbero potenzialmente migliorare l’efficienza sia dell’assorbimento della luce che della separazione di carica. Per questa ragione, è stata misurata la funzione lavoro di nanoshell depositate su substrati di ITO con la tecnica Kelvin probe. Scegliendo opportunamente lo spessore dello shell, se pre-funzionalizzare l’ITO e il livello di ricoprimento di particelle, è possibile variare la funzione lavoro dell’elettrodo nell’intervallo 3.9 – 4.4 eV

Saturable absorption of femtosecond laser pulses at surface plasmon resonance in gold nanoshells

In this work, we present an investigation of the nonlinear optical properties of nanoshells of different size in solutions and deposited on glass substrates using a single beam z-scan method at a wavelength of 806 nm with laser duration of 170 fs. Structural properties of gold nanoshells of about 150 and 220 nm, prepared in water, are characterized by AFM and TEM microscopy. It is found that, in general, they behave as saturable absorbers. The level of saturation depends on the relative overlap between the plasmon resonance of nanoshells and the laser excitation wavelengths. The nonlinear absorption coefficient, obtained by fitting the experimental results, is of the order of -10-11 cmW-1

Femtosecond nonlinear absorption of gold nanoshells at surface plasmon resonance

The nonlinear optical absorption of gold nanoshells (Au NSs) of different size, in water, was investigated using open aperture z-scan technique with femtosecond laser pulses at 806 nm. It is found that, in general, NSs behave as saturable absorbers. The level of saturation depends on the Au NSs structure and precisely on the ratio between the core size and shell thickness. The measured values of the nonlinear absorption coefficient show a dependence on both the repetition rate and the pulse energy. An average value of the nonlinear absorption coefficient beta = -4.5 +/- 1.0 x 10(-11) cm W(-1) is obtained from z-scan data of core-shell particles of inner and outer radius 95 and 110 nm, respectively, measured at 20 Hz repetition rate in the energy range 120-300 nJ