The sol-gel technique has many advantages over the other mechanism for synthesizing metal oxide nanoparticles such as being simple, cheap and having low temperature and pressure. Utilization of waste materials as a precursor for synthesis makes the whole process cheaper, green and sustainable. Calcium Oxide nanoparticles have been synthesized from eggshell through the sol-gel method. Raw eggshell was dissolved by HCl to form CaCl 2 solution, adding NaOH to the solution dropwise to agitate Ca (OH) 2 gel and finally drying the gel at 900 • C for 1 h. The synthesized nanoparticle was characterized by scanning electron microscope (SEM), Fourier-transform infrared spectroscopy (FTIR), X-Ray fluorescence (XRF) and X-ray diffraction (XRD). The FTIR and XRD results have clearly depicted the synthesis of calcium oxide from eggshell, which is mainly composed of calcium carbonate. The FE-SEM images of calcium oxide nanoparticles showed that the particles were almost spherical in morphology. The particle size of the nanoparticles was in the range 50 nm-198 nm. Therefore, waste eggshell can be considered as a promising resource of calcium for application of versatile fields.

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We report a quantum ring-like toroidal cavity naturally formed in a vertical-cavity-like active microdisk plane due to Rayleigh's band of whispering gallery modes. The √ T -dependent redshift and a square-law property of microampere-range threshold currents down to 2 µA are consistent with a photonic quantum wire view, due to whispering gallery mode-induced dimensional reduction.PACS number: 42.55. Sa, 42.60.Da For the last several years, there have been intensive developments of microdisk semiconductor lasers of whispering gallery(WG) modes for low-power and high-density photonic array applications. These efforts of earlier photo-pumped thumbtack-type WG lasers [1] have been evolving to photonic-wire lasers [2] and electro-pumped thumbtack-type WG lasers [3,4] of submilliampere threshold currents.In this letter, we demonstrate a cylindrical vertical-cavity surface-emitting laser(VCSEL)-like diode that exhibits WG modes with unusual photonic quantum ring(PQR) characteristics such as µA-range threshold currents and spectral √ Tdependence, in addition to the usual VCSEL mode. We will thus illustrate and analyze the two-threshold behavior of successive lasings, first the PQR and then the VC-SEL as well. Indeed, the quantum wire behavior of the PQR is vividly demonstrated in the √ T -dependent spectral peak shift data. We note that the quantum-ring-like WG modes are naturally formed in the circumferential Rayleigh band region [5] of the active microdisk of a regular multi-quantum-well VCSEL-like structure but without any intentional and real quantum ring patterning.The PQR device differs from the previous WG lasers [ [1][2][3][4]6] in that the vertical confinement is improved by the top and bottom DBR layers, and that stripe or segmented top electrodes are used for vertical output coupling. The metal-organic vapor-phase epitaxy-grown device employs a one-λ thick active layer with four 80 A Al 0.11 Ga 0.89 As quantum wells(QWs), whose details have been described elsewhere [8,9,12]. In the active disk plane, the PQR region is defined by Rayleigh's bandwidth, W Rayleigh = (φ/2)(1 − n ef f /n), where the WG mode occurs, which is well described in Ref. [7]: Rayleigh's annular band is defined by the active disk's radius R(= φ/2) for outer boundary and the inner reflection point r in = Rn M /n, where n is the refractive index of the active medium and n M is the effective refractive An exploded segment shows the effective toroidal structure of the PQR, where R is the index-guided outer limit and rin is the inner reflection limit which may also be reinforced by gain guiding. The radial evanescent field results from forward and backward helical traveling waves, and its intensity peaks at a distance t ≤ 1 µm from the outer boundary.The calculated profile of the annular WG emission based on Rayleigh's Bessel function analysis is shown in Fig. 1(a) for our device with R = 7.5 µm. The azimuthal mode number is rather large here, M = 2πRn ef f /λ = 188, and hence the 376 azimuthal peaks are not well distinguishable, unlike the i...

A wide variety of fillers are currently used in more than twenty types of polymer resins, although four of them alone (polypropylene, polyamides, thermoplastic polyesters, and polyvinyl chloride) account for 90% of the market of mineral fillers in plastics. Polypropylene (PP) and PVC dominate the market for calcium carbonate. PP is a versatile reinforcement material that can meet engineering and structural specifications and is widely used for automotive components, home appliances, and industrial applications. Talc, mica, clay, kaolin, wollastonite, calcium carbonates, feldspar, aluminum hydroxide, glass fibers, and natural fibers are commonly used in fillers. Among these, calcium carbonate (both natural and synthetic) is the most abundant and affords the possibility of improved surface finishing, control over the manufacture of products, and increased electric resistance and impact resistance. Meeting the global challenge to reduce the weight of vehicles by using plastics is a significant issue. The current the global plastic and automobile industry cannot survive without fillers, additives, and reinforcements. Polypropylene is a major component of the modern plastic industry, and currently is used in dashboards, wheel covers, and some engine parts in automobiles. This article reports that the use of calcium carbonate fillers with polypropylene is the best choice to enhance the mechanical properties of plastic parts used in automobiles.

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The influences of surface potential formed on the address electrode by the applied pulsed voltage V a combined with the accumulated charge on the behaviour of microdischarge in a unit cell of an ac-type plasma display panel was investigated in the sustain periods by systematically varying the timing and amplitude of V a . Using a special panel, which enabled three-dimensional observation from the front and side, the spatiotemporal behaviour of excited Xe atoms in the metastable (1s 5 ) and resonance (1s 4 ) states and the 2p state was observed by microscopic laser absorption spectroscopy and optical emission spectroscopy, respectively. When V a was applied synchronously with the rise of the sustain pulse, the discharge started from the temporal anode side and the density of Xe*(1s 5 ) atoms distributed over the whole area between the sustain and address electrodes. When the rise of V a was set in between the fall and the rise of successive sustain pulses, a pre-discharge occurred between the address electrode and one of the sustain electrodes which had worked as a preceding anode. In both cases, the production efficiency of excited atoms was enhanced compared with the case without V a , but the increment in the former case was larger than in the latter. However, there was an optimum amplitude of V a of about 60 V.

In this study, we utilized lime mud waste from paper mills to synthesize calcium hydroxide (Ca(OH)2) nanoparticles (NPs) and investigate their application for the removal of phosphorus from aqueous solution. The NPs, composed of green portlandite with hexagonal shape, were successfully produced using a precipitation method at moderately high temperature. The crystal structure and characterization of the prepared Ca(OH)2 nanoparticles were analyzed by field emission scanning electron microscopy, Fourier transform infrared spectroscopy, and X-ray diffraction. The effects of Ca(OH)2 NP dosage and contact time on removal of phosphorus were also investigated. The results show that the green portlandite NPs can effectively remove phosphorus from aqueous solution. The phosphorus removal efficiencies within 10 min are 53%, 72%, 78%, 98%, and 100% with the different mass ratios of Ca(OH)2 NPs/phosphorus (CNPs/P) of 2.2, 3.5, 4.4, 5.3, and 6.2, respectively. Due to the efficient phosphorus removal, the calcium hydroxide nanoparticles (CNPs) could be a potential candidate for this application in domestic or industrial wastewater treatment.

For decades, researchers have debated whether climate change has an adverse impact on diseases, especially infectious diseases. They have identified a strong relationship between climate variables and vector’s growth, mortality rate, reproduction, and spatiotemporal distribution. Epidemiological data further indicates the emergence and re-emergence of infectious diseases post every single extreme weather event. Based on studies conducted mostly between 1990-2018, three aspects that resemble the impact of climate change impact on diseases are: (a) emergence and re-emergence of vector-borne diseases, (b) impact of extreme weather events, and (c) social upliftment with education and adaptation. This review mainly examines and discusses the impact of climate change based on scientific evidences in published literature. Humans are highly vulnerable to diseases and other post-catastrophic effects of extreme events, as evidenced in literature. It is high time that human beings understand the adverse impacts of climate change and take proper and sustainable control measures. There is also the important requirement for allocation of effective technologies, maintenance of healthy lifestyles, and public education.