High Temperature Dielectrics in the Ceramic System K₀.₅Bi₀.₅TiO₃-Ba(Zr₀.₂Ti₀.₈)O₃-Bi(Zn₂⁄₃Nb₁⁄₃)O₃

Ceramics in the system (1-x)[0.5 K₀.₅Bi₀.₅TiO₃-0.5Ba(Zr₀.₂Ti₀.₈)O₃]-xBi(Zn₂⁄₃Nb₁⁄₃)O₃ have been fabricated by a solid-state processing route for compositions x ≤ 0.3. The materials are relaxor dielectrics. The temperature of maximum relative permittivity, Tm, decreased from 150 °C for composition x = 0, to 70 °C for x = 0.2. The x = 0.2 sample displayed a wide temperature range of stable relative permittivity, εr, such that εr = 805 ± 15% from −20 °C to 600 °C (1 kHz). Dielectric loss tangent was ≤ 0.02 from 50 °C to 450 °C (1 kHz), but due to the tanδ dispersion peak, the value increased to 0.09 as temperatures fell from 50 °C to −20 °C. Values of dc resistivity were of the order of ~ 109 Ω m at 300 °C. These properties are promising in the context of developing new high temperature capacitor materials

Lead-free piezoelectric K0.5Bi0.5TiO3–Bi(Mg0.5Ti0.5)O3 ceramics with depolarisation temperatures up to ~220 C

The properties of K0.5Bi0.5TiO3-rich ceramic solid solutions in the system (1 - x)K0.5Bi0.5TiO3– xBi(Mg0.5Ti0.5)O3 are reported. The highest values of piezoelectric charge coefficient, d33, and field-induced strains are found in compositions located close to a compositional boundary between single-phase tetragonal and mixed tetragonal ? cubic perovskite phases. Maximum d33 values were *150 pC/N for x = 0.03, with positive strains of *0.25 %; the x = 0.04 composition had a d33 * 133 pC/N and strain of 0.35 % (bipolar electric field, 50 kV/ cm, 1 Hz). Depolarisation temperature Td is an important selection criterion for any lead-free piezoelectric for actuator or sensor applications. A Td of *220 C for x = 0.03 is *100 C higher than for the widely reported Na0.5Bi0.5TiO3–BaTiO3 system, yet d33 values and strains are similar, suggesting the new material is worthy of further attention as a lead-free piezoceramic for elevated temperature applications

Comparison of Efficiencies of Neurological Physical Examination, Neurothesiometer and PainDETECT Questionnaire in Diagnosing Diabetic Neuropathy

Objective: To compare the efficacies of neurological physical examination, neurothesiometer and PainDETECT questionnaire in diagnosing diabetic neuropathy. Study Design: Prospective cross-sectional Place and Duration of Study: Department of General Medicine, Nishtar Hospital Multan, Pakistan from 1st December 2018 to 10th March 2019. Materials and Methods: One hundred and four patients of both type 1 and type 2 diabetes visiting the outdoor department were included in this study. They were assessed by lab results of glycosylated hemoglobin, fasting and random blood sugar levels and neurological physical examination. Results: The physical examination with Michigan Neuropathy Screening instrument showed that around 29 of the patients were having established neuropathy. The PainDETECT questionnaire on the other hand showed about 42 patients having a definitive neuropathy while the neurothesiometer showed that 79 of the total patients had varying degrees of neuropathy. Conclusion: The neurothesiometer is a better diagnostic tool for diagnosing diabetic neuropathy in patients

Characterization of carbon monoxide, methane and nonmethane hydrocarbons in emerging cities of Saudi Arabia and Pakistan and in Singapore

We investigate the composition of 63 C2-C10 nonmethane hydrocarbons (NMHCs), methane (CH4) and carbon monoxide (CO), in Jeddah, Mecca, and Madina (Saudi Arabia), in Lahore, (Pakistan), and in Singapore. We established a database with which to compare and contrast NMHCs in regions where ambient levels and emissions are poorly characterized, but where conditions are favorable to the formation of tropospheric ozone, and where measurements are essential for improving emission inventories and modeling. This dataset will also serve as a base for further analysis of air pollution in Western Saudi Arabia including, but not limited to, the estimation of urban emissions and long range pollution transport from these regions. The measured species showed enhanced levels in all Saudi Arabian cities compared to the local background but were generally much lower than in Lahore. In Madina, vehicle exhaust was the dominant NMHC source, as indicated by enhanced levels of combustion products and by the good correlation between NMHCs and CO, while in Jeddah and Mecca a combination of sources needs to be considered. Very high NMHC levels were measured in Lahore, and elevated levels of CH4 in Lahore were attributed to natural gas. When we compared our results with 2010 emissions from the MACCity global inventory, we found discrepancies in the relative contribution of NMHCs between the measurements and the inventory. In all cities, alkenes (especially ethene and propene) dominated the hydroxyl radical (OH) reactivity (kOH) because of their great abundance and their relatively fast reaction rates with OH

Deconstructing Local Adaptation Plans for Action (LAPAs) - Analysis of Nepal and Pakistan LAPA initiatives

This paper analyses the organizational and implementation design strategies of two ongoing Local Adaptation Plan for Action (LAPA) initiatives in Nepal and Pakistan. LAPA is considered an answer for institutionalized local-level adaptation planning that aims to capture local needs and direct resources to where, when and by whom these are most needed. While both Nepal and Pakistan LAPAs have similar objectives of bottom-up planning, the operational and structural designs of the two LAPAs are very distinct, leading to different outcomes. Different internal and external factors such as age and size of LAPA, technology, local institutional arrangements, core process and environment also exert significant structural tensions on the planned organizational design of LAPAs that may inhibit delivery of their objectives

High temperature dielectric ceramics: a review of temperature-stable high-permittivity perovskites

Recent developments are reviewed in the search for dielectric ceramics which can operate at temperatures >200 °C, well above the limit of existing high volumetric efficiency capacitor materials. Compositional systems based on lead-free relaxor dielectrics with mixed cation site occupancy on the perovskite lattice are summarised, and properties compared. As a consequence of increased dielectric peak broadening and shifts to peak temperatures, properties can be engineered such that a plateau in relative permittivity–temperature response (εr–T) is obtained, giving a ±15 %, or better, consistency in εr over a wide temperature range. Materials with extended upper temperature limits of 300, 400 and indeed 500 °C are grouped in this article according to the parent component of the solid solution, for example BaTiO3 and Na0.5Bi0.5TiO3. Challenges are highlighted in achieving a lower working temperature of −55 °C, whilst also extending the upper temperature limit of stable εr to ≥300 °C, and achieving high-permittivity and low values of dielectric loss tangent, tan δ. Summary tables and diagrams are used to help compare values of εr, tan δ, and temperature ranges of stability for different material

Phase space barriers and dividing surfaces in the absence of critical points of the potential energy: Application to roaming in ozone

We examine the phase space structures that govern reactiondynamics in the absence of critical points on the potential energy surface. We show that in the vicinity of hyperbolic invariant tori, it is possible to define phase space dividing surfaces that are analogous to the dividing surfaces governing transition from reactants to products near a critical point of the potential energy surface. We investigate the problem of capture of an atom by a diatomic molecule and show that a normally hyperbolic invariant manifold exists at large atom-diatom distances, away from any critical points on the potential. This normally hyperbolic invariant manifold is the anchor for the construction of a dividing surface in phase space, which defines the outer or loose transition state governing capture dynamics. We present an algorithm for sampling an approximate capture dividing surface, and apply our methods to the recombination of the ozone molecule. We treat both 2 and 3 degrees of freedom models with zero total angular momentum. We have located the normally hyperbolic invariant manifold from which the orbiting (outer) transition state is constructed. This forms the basis for our analysis of trajectories for ozone in general, but with particular emphasis on the roaming trajectories

Towards Understanding the Roaming Mechanism in H + MgH → Mg + HH Reaction

The roaming mechanism in the reaction H + MgH →Mg + HH is investigated by classical and quantum dynamics employing an accurate ab initio three-dimensional ground electronic state potential energy surface. The reaction dynamics are explored by running trajectories initialized on a four-dimensional dividing surface anchored on three-dimensional normally hyperbolic invariant manifold associated with a family of unstable orbiting periodic orbits in the entrance channel of the reaction (H + MgH). By locating periodic orbits localized in the HMgH well or involving H orbiting around the MgH diatom, and following their continuation with the total energy, regions in phase space where reactive or nonreactive trajectories may be trapped are found. In this way roaming reaction pathways are deduced in phase space. Patterns similar to periodic orbits projected into configuration space are found for the quantum bound and resonance eigenstates. Roaming is attributed to the capture of the trajectories in the neighborhood of certain periodic orbits. The complex forming trajectories in the HMgH well can either return to the radical channel or “roam” to the MgHH minimum from where the molecule may react