Characterisation of different polymorphs of tris(8-hydroxyquinolinato)aluminium(III) using solid-state NMR and DFT calculations

<p>Abstract</p> <p>Background</p> <p>Organic light emitting devices (OLED) are becoming important and characterisation of them, in terms of structure, charge distribution, and intermolecular interactions, is important. Tris(8-hydroxyquinolinato)-aluminium(III), known as Alq₃, an organomettalic complex has become a reference material of great importance in OLED. It is important to elucidate the structural details of Alq₃in its various isomeric and solvated forms. Solid-state nuclear magnetic resonance (NMR) is a useful tool for this which can also complement the information obtained with X-ray diffraction studies.</p> <p>Results</p> <p>We report here ²⁷Al one-dimensional (1D) and two-dimensional (2D) multiple-quantum magic-angle spinning (MQMAS) NMR studies of the meridional (<it>α</it>-phase) and the facial (<it>δ</it>-phase) isomeric forms of Alq₃. Quadrupolar parameters are estimated from the 1D spectra under MAS and anisotropic slices of the 2D spectra and also calculated using DFT (density functional theory) quantum-chemical calculations. We have also studied solvated phase of Alq₃containing ethanol in its lattice. We show that both the XRD patterns and the quadrupolar parameters of the solvated phase are different from both the <it>α</it>-phase and the <it>δ</it>-phase, although the fluorescence emission shows no substantial difference between the <it>α</it>-phase and the solvated phase. Moreover, we have shown that after the removal of ethanol from the matrix the solvated Alq₃has similar XRD patterns and quadrupolar parameters to that of the <it>α</it>-phase.</p> <p>Conclusion</p> <p>The 2D MQMAS experiments have shown that all the different modifications of Alq₃have ²⁷Al in single unique crystallographic site. The quadrupolar parameters predicted using the DFT calculation under the isodensity polarisable continuum model resemble closely the experimentally obtained values. The solvated phase of Alq₃containing ethanol has structural difference from the <it>α</it>-phase of Alq₃(containing meridional isomer) from the solid-state NMR studies. Solid-state NMR can hence be used as an effective complementary tool to XRD for characterisation and structural elucidation.</p

Leveraging Rural Energy Investment for Parasitic Disease Control: Schistosome Ova Inactivation and Energy Co-Benefits of Anaerobic Digesters in Rural China

Cooking and heating remain the most energy intensive activities among the world's poor, and thus improved access to clean energies for these tasks has been highlighted as a key requirement of attaining the major objectives of the UN Millennium Development Goals. A move towards clean energy technologies such as biogas systems (which produce methane from human and animal waste) has the potential to provide immediate benefits for the control of neglected tropical diseases. Here, an assessment of the parasitic disease and energy benefits of biogas systems in Sichuan Province, China, is presented, highlighting how the public health sector can leverage the proliferation of rural energy projects for infectious disease control. ova) counted at the influent of two biogas systems were removed in the systems when adjusted for system residence time, an approximate 1-log removal attributable to sedimentation. Combined, these inactivation/removal processes underscore the promise of biogas infrastructure for reducing parasite contamination resulting from nightsoil use. When interviewed an average of 4 years after construction, villagers attributed large changes in fuel usage to the installation of biogas systems. Household coal usage decreased by 68%, wood by 74%, and crop waste by 6%. With reported energy savings valued at roughly 600 CNY per year, 2–3 years were required to recoup the capital costs of biogas systems. In villages without subsidies, no new biogas systems were implemented.Sustainable strategies that integrate rural energy needs and sanitation offer tremendous promise for long-term control of parasitic diseases, while simultaneously reducing energy costs and improving quality of life. Government policies can enhance the financial viability of such strategies by introducing fiscal incentives for joint sanitation/sustainable energy projects, along with their associated public outreach and education programs

Study of drying characteristics of large-cardamom

India is the largest producer of large-cardamom in the world with 54% share in world production followed by Nepal (33%) and Bhutan (13%). For long-duration storage of cardamom and in order to bring out its aroma, the fresh cardamom capsules (with 80–85% moisture) has to be dried immediately after harvesting to bring down its moisture content to less than 10% (w.b.) through a curing (drying) process. Still a primitive and inefficient (operating efficiency level of about 5–15%) smoking method (using traditional bhatti) is being used for drying of large-cardamom resulting in huge (estimated 20,000 MT/yr) wastage of fuel wood and poor (charred and blackened) quality product. This paper gives a brief description of efforts made to obtain basic drying parameters of large-cardamom (which is a pre-requisite for dryer design) under different operating conditions.© Elsevie

Suite of off-grid options in South Asia

This chapter provides a review of alternative off-grid electrification options in South Asia. It covers four elements: the technical dimension, business models, regulatory governance and sustainability dimension of off-grid solutions. It concludes that in order to go beyond lighting applications, more careful consideration and investigation is required for electricity supply using local distribution networks (or mini-grids), particularly using hybrid technological options

Evaluation of short-term health effects among rural women and reduction in household air pollution due to improved cooking stoves: quasi experimental study

An improved efficient stove is the mainstay intervention to reduce household air pollution (HAP) associated with biomass fuel use. It potentially addresses the adverse health outcomes by reducing smoke exposure, fuel consumption, and cooking time. This study evaluated two stove intervention programs and compared them for health effects (respiratory and eye symptoms, lung function, blood pressure and burns) among women who were the main cook of the household. A total of 83 and 134 improved and 209 and 179 traditional stoves in Sindh and Punjab provinces of Pakistan, respectively, were evaluated after 3 months of installation, during June to September, 2014. Twenty-four-hour particulate matter (aRR 0.16, CI 0.11, 0.22), chest tightness (aRR 0.23, CI 0.17, 0.31), attack of asthma (aRR 0.33, CI 0.22, 0.49) (p \u3c 0.001), sandy eyes (aRR 0.63, CI 0.47, 0.97), and itching in eyes (aRR 0.62, CI 0.41, 0.95 (p \u3c 0.050) were present. While in Punjab program, risk reduction for phlegm (aRR 0.60, CI 0.45, 0.81) and protection from burns (aRR 0.56, CI 0.34, 0.91) were observed among women. Mean peak expiratory flow was higher among women using improved stoves in Sindh program (31.58, CI 17.90, 45.25 L/min) only. Overall, the positive health impact was greater among those women using closed kitchens. Interventions with improved stoves can have favorable health impact among women. However, variations in health gains were noted among the two programs, as well as greater impact among women using closed kitchen