Defining pathways to healthy sustainable urban development.

Goals and pathways to achieve sustainable urban development have multiple interlinkages with human health and wellbeing. However, these interlinkages have not been examined in depth in recent discussions on urban sustainability and global urban science. This paper fills that gap by elaborating in detail the multiple links between urban sustainability and human health and by mapping research gaps at the interface of health and urban sustainability sciences. As researchers from a broad range of disciplines, we aimed to: 1) define the process of urbanization, highlighting distinctions from related concepts to support improved conceptual rigour in health research; 2) review the evidence linking health with urbanization, urbanicity, and cities and identify cross-cutting issues; and 3) highlight new research approaches needed to study complex urban systems and their links with health. This novel, comprehensive knowledge synthesis addresses issue of interest across multiple disciplines. Our review of concepts of urban development should be of particular value to researchers and practitioners in the health sciences, while our review of the links between urban environments and health should be of particular interest to those outside of public health. We identify specific actions to promote health through sustainable urban development that leaves no one behind, including: integrated planning; evidence-informed policy-making; and monitoring the implementation of policies. We also highlight the critical role of effective governance and equity-driven planning in progress towards sustainable, healthy, and just urban development

Spectroscopic Investigation of Rare-Earth Doped Phosphate Glasses Containing Silver Nanoparticles

Phosphate glasses having compositions $(59.5-x)P_2O_5-40MgO-xAgCl-0.5Er_2O_3$, where x=0, 1.5 mol.% is prepared using melt-quenching technique. Infrared, absorption and photoluminescence spectra of $Er^{3+}$-doped magnesium phosphate glasses have been reported. The amorphous nature of the host glass is confirmed by X-ray diffraction technique. Transmission electron microscope image confirms the existence of silver nanoparticles inside the glass matrix. The localized surface plasmon resonance band of silver is found to be located around ≈ 528 nm for the $Er^{3+}$ free sample. A frequency upconversion process from infrared to visible is observed on excitation with 797 nm radiation. Furthermore, an enhancement in the emission at 540 nm and 632 nm is found due to the local field effect of silver nanoparticles. Our findings may contribute towards the development of solid state laser and sensors

Enhanced frequency up-conversion in er3+-doped sodium lead tellurite glass containing silver nanoparticles.

A series of silver nanoparticle embedded in erbium-doped tellurite glasses were synthesized using a one step melt-quenching method. Density and refractive index of glasses were measured. Thermal and optical characterizations were performed and plasmon bands of elliptical nanoparticles were observed. An enhancement of green (525 and 550 nm) and red (632 nm) lines in luminescence spectra of Er3+-doped silver-embedded tellurite glass was recorded and explained by energy transfer mechanism from silver nanoparticles to erbium ion in addition to enhanced local field in vicinity of metallic nanoparticles in the glass. The presence of nanoparticles was confirmed by transmission electron microscopy imaging and reduction of silver ions to silver neutral particles discussed through the redox potential estimation in probable reactions. Silver-erbium co-doped tellurite glass exhibits strong novel optical properties which nominate it as the promising glass for laser, color displays, and photonic applications

Annealing time dependent up-conversion luminescence enhancement in magnesium-tellurite glass

Silver nanoparticles (NPs) embedded Er3+ ions doped magnesium-tellurite glasses are prepared using melt quenching technique. Heat treatment with different time intervals above the glass transition temperature is applied in order to reduce the silver ions (Ag+) to silver NPs (Ago). The transmission electron microscopy (TEM), differential thermal analyses (DTA), UV-vis-NIR absorption spectroscopy and photoluminescence (PL) spectroscopy are used to examine annealing time dependent structural and optical properties. The characteristics temperatures such as glass transition temperature (Tg), crystallization temperature (Tc) and melting temperature (Tm) obtained from DTA for an as prepared sample are 322 °C, 450 °C and 580 °C, respectively. TEM image clearly shows the homogeneous distribution of silver NPs with an average diameter ∼12 nm. The observed localized surface plasmon resonance (LSPR) band is evidenced at 534 nm. Furthermore, the infrared to visible frequency up-conversion (UC) emission under 786 nm excitation exhibits three emission bands centered at 532 nm, 554 nm and 634 nm corresponding to 2H11/2→ 4I15/2, 4S3/2→ 4I15/2 and 4F9/2→ 4I15/2 transitions of Er3+, respectively. Intensity of all the bands is found to enhance by increasing the annealing time up to 24 h. However, further increase in the annealing time duration (∼40 h) reduces the intensity. Enhancement in the luminescence intensity is understood in terms of the local field effect of the silver NPs whereas the quenching is attributed to the energy transfer from Er3+ ions to silver NP