Decrease In Emission Intensity Research Articles

Disentangling the ranges: climate policy scenarios for China and India

Greenhouse gas emissions in China and India have been increasing rapidly over the last decade. Scenario studies can provide insight into expected future trends and the emission reduction potential in these regions. The scenarios show that growing population, gross domestic product, and energy demand are likely to lead to a further increase in emissions. At the same time, a decreasing emission intensity would still allow to create decarbonization scenarios in line with the requirements for reaching a maximal warming of 2 °C. There is, however, a wide range of assumptions across these studies. Based on the literature review, this paper observes that key assumptions in scenarios developed by national institutes in China and India differ from those presented by international studies or modeling teams. We explore how this—and other factors like data availability—may influence the interpretation of the scenarios and how international and national modeling groups could learn from each other. Our main recommendation is for more extensive collaboration between national and international research groups, so that national and international scenario studies can be compared in more detail in order to support international negotiations.

Resource use and greenhouse gas intensity of Australian beef production: 1981–2010

Over the past three decades major changes have occurred in Australia's beef industry, affecting productivity and potentially the amount of resources used and environmental impacts from production. Using a life cycle assessment (LCA) approach with a ‘cradle-to-farm gate’ boundary the changes in greenhouse gas (GHG) emission intensity and key resource use efficiency factors (water use, fossil fuel energy demand and land occupation) are reported for the 30 years from 1981 to 2010, for the Australian beef industry. The analysis showed that over the three decades since 1981 there has been a decrease in GHG emission intensity (excluding land use change emissions) of 14% from 15.3 to 13.1 kg CO2-e/kg liveweight (LW). The improvement was largely due to efficiency gains through heavier slaughter weights, increases in growth rates in grass-fed cattle, improved survival rates and greater numbers of cattle being finished on grain. However, the increase in supplement and grain use on farms, and the increase in feedlot finishing, resulted in a twofold increase in fossil fuel energy demand for beef production over the same time. Fresh water consumption for beef production dropped to almost a third from 1465 L/kg LW in 1981 to 515 L/kg LW in 2010. Three contributing factors for this dramatic reduction in water use were: (i)an increase in the competitive demand for irrigation water, resulting in a transfer away from pasture for cattle to higher value industries such as horticulture, (ii) an initiative to cap free flowing artesian bores in the rangelands, and (iii) an overall decline in water available for agriculture compared to industrial and domestic uses. While there was higher uncertainty relating to estimates of land occupation and emissions from land use (LU) and direct land use change (dLUC), an inventory of land occupation indicated a decline in non-arable land occupation of about 19%, but a sevenfold increase in land occupation for feed production, albeit from a low base in 1981. GHG emissions associated with LU and dLUC for grazing were estimated to have declined by around 42% since 1981, due largely to legislated restrictions on broad-scale deforestation which were introduced progressively between 1996 and 2006. This paper discusses the prospects and challenges for further gains in resource use efficiency and reductions in greenhouse gas intensity for Australian beef production.

Effect of nanosize micelles of ionic and neutral surfactants on the photophysics of protonated 6-methoxyquinoline: Time-resolved fluorescence study

The excited state dynamic studies have been carried out to investigate the effects of micellar surface charge on the photophysics of protonated 6-methoxyquinoline (6MQ+) in anionic, sodium dodecylsulphate (SDS), cationic, cetyltrimethylammonium bromide (CTAB) and neutral, triton X-100 (TX100) surfactant at premicellar, micellar and postmicellar concentrations in aqueous phase at room temperature. At premicellar concentrations of SDS, there is a slight decrease in emission intensity and at micellar and postmicellar concentrations, increase in emission intensity and blue shift of spectrum has been observed. The blue shift in fluorescence spectrum and slight increase in quantum yield are attributed to incorporation of solute molecule to the micelles. Edge excitation red shift (EERS) in fluorescence maximum of 6MQ+ has been observed in all the surfactant solutions studied. The EERS has been ascribed in terms of solvent relaxation process. In SDS surfactant system, due to heterogeneous restricted motion of solvent molecules, the solvent viscosity increases which results in an increase in net magnitude of EERS. The fluorescence decay components of 6MQ+ fit with multi exponential functions in all the micellar systems studied. The location of the probe molecule in micellar systems is justified by a variety of spectral parameters such as refractive index, dielectric constant, ET (30), EERS, average fluorescence decay time, radiative and non radiative rate constants, and rotational relaxation time.

A new aza-BODIPY based NIR region colorimetric and fluorescent chemodosimeter for fluoride

The synthesis and characterization of a novel NIR region fluoride sensor, that makes use of the aza-boron-dipyrromethene (aza-BODIPY) fluorophore, is described. An arylmagnesium bromide was formed by reacting 4-bromophenol with a tert-butyldimethylsilyl protecting group and magnesium, which was then used to prepare the aza-BODIPY through a reaction with phthalonitrile. The unusually strong affinity between the fluoride anion and silicon is used to create a sensor dye, which exhibits a highly specific, rapid colorimetric and ‘turn-off’ fluorescence response for F− in solution and in living HeLa cells. With F−, there is enhanced intramolecular charge transfer within the S1 state and this results in efficient nonradiative decay and hence in a marked decrease in fluorescence emission intensity.

Improved efficiency of ternary the blend polymer solar cells by doping a narrow band gap polymer material

A series of P3HT:PC71BM polymer solar cells (PSCs) with different PIDTDTQx doping concentrations were fabricated to investigate the effect of the PIDTDTQx as a complementary electron donor on the performance of PSCs. The power conversion efficiency (PCE) of the optimized ternary blend PSCs (with 2 wt% PIDTDTQx) reached 3.87%, which is 28% higher than that of the PSCs based on P3HT:PC71BM (control cells). The short-circuit current density (Jsc) was increased to 10.20 mA/cm2 compared with the control cells. The PCE improvement could be attributed to more photon harvest and charge carrier transport by appropriate doping PIDTDTQx. The energy transfer from P3HT to PIDTDTQx was demonstrated from the 650 nm emission intensity decrease and the red-shifted emission peaks from 725 nm to 737 nm along with the increase of PIDTDTQx doping concentrations.

Effect of ultraviolet-illumination and sample ambient on photoluminescence from zinc oxide nanocrystals

We report an effect of measurement conditions on the photoluminescence intensities of zinc oxide nanoparticles. It was found that in vacuum under UV illumination intensity of near-band edge emission increases while defect related emission intensity decreases. We attribute this effect to a decrease in the depletion region width due to oxygen desorption on the surface of the zinc oxide nanocrystals.

Synthesis, structure and luminescence of novel co-crystals based on bispyridyl-substituted α,β-unsaturated ketones with coformers

Based on 2,6-bis((pyridin-4-yl)methylene)cyclohexanone (A) and N-methyl-3,5-bis((pyridin-4-yl)methylene)-4-piperidone (B) with coformers, three novel macrocyclic co-crystals, (A)⋅(resorcinol) (1), (A)⋅(1,3,5-benzenetriol) (2), (B)2⋅(1,3,5-benzenetriol)2 (3) and three chain co-crystals, (A)⋅(hydroquinone) (4), (A)⋅(isophthalic acid) (5), (B)⋅(isophthalic acid) (6) have been synthesized and structurally characterized by IR, 1H NMR and X-ray crystal structure analysis. Structural analysis indicates that four-component macrocycles in 1–3 are generated from “clip-like” resorcinol templates and building blocks, while 4–6 show infinite H-bonding chains. In addition, the luminescent properties of A, B and 1–6 are investigated primarily in the solid state. Compared with free building blocks, 1–6 are blue-shifted 55–60nm with decreasing emission intensities in spite of the enhancement in 6. The change of luminescent properties might be caused mainly by incorporation of coformers into co-crystals, including H-bonds, molecular conformations, arranging dispositions and π–π characteristics. It might have potential applications for crystal engineering to construct patentable crystals with interesting luminescent properties.

Spectroscopic and microscopic evaluation of immobilized cytochrome c interaction with cyanide/arsenic ligands in quantitative analysis

The electrochemical, spectroscopic and microscopic analyses of cytochrome c and its immobilization on bare glassy carbon (GC) and platinum (Pt) electrodes were performed. Cytochrome c interaction was examined by studying cyanide and arsenic as model compounds for these types of behavior. Subtractively normalized interfacial Fourier transform infrared (SNIFTIR) spectroscopy, fluorescence and electrochemical methods, Fourier transform infrared (FTIR) spectroscopy and atomic force microscopy (AFM) were used to characterize the protein in the immobilized state and to confirm that the protein was not denatured upon binding to the pre-treated bare GC and Pt electrodes. The spherical morphology of the immobilized protein, which is typical of native cytochrome c, was observed using AFM. The protein binding was monitored as a decrease in peak currents (by CV) for the immobilized protein. Under analysis was also a decrease in emission intensities by fluorescence in solution, by the FTIR and SNIFTIR spectroscopies. Fluorescence and AFM proved the existence of the binding process between the protein and the analytes. This behavior was confirmed by the FTIR and SNIFTIR spectroscopies, which gave evidence that the binding event took place at the amino acids side chain of the protein.

Laser-induced breakdown spectroscopy (LIBS) of a high-pressure CO2-water mixture: application to carbon sequestration.

Geologic carbon storage in deep saline aquifers is considered a feasible and possible approach of mitigating the problem of increasing greenhouse gas emissions. However, there are latent risks in which carbon dioxide (CO2) could migrate from the deep saline formations to shallower aquifers. In the event of a significant CO2 leakage to an underground source of drinking water, CO2 will dissolve in the water, thereby increasing its acidity, which could potentially enhance the solubility of various aquifer constituents, including hazardous compounds, subsequently compromising groundwater quality due to increased concentration of aqueous metals. In this paper we explore the possibility of detecting such leakage by the use of laser-induced breakdown spectroscopy (LIBS). The experiments were conducted in calcium chloride solution at three pressures of 10, 50, and 120 bar. To evaluate the direct effect of elevated CO2 on the intensity of calcium emission lines (422.67 and 393.37 nm), we also performed experiments with pure nitrogen (N2) gas, offering large water solubility contrast. We found that when performed in presence of CO2, LIBS showed only a modest decrease in Ca emission intensity from 10 to 120 bar compared to N2. These results indicate that LIBS is a viable tool for measuring brine/water contents in high-pressure CO2 environment and can be applied for monitoring CO2 leakage and displaced brine migration.

Synthesis of Au-decorated V2O5@ZnO heteronanostructures and enhanced plasmonic photocatalytic activity.

A ternary plasmonic photocatalyst consisting of Au-decorated V2O5@ZnO heteronanorods was successfully fabricated by an innovative four-step process: thermal evaporation of ZnO powders, CVD of intermediate on ZnO, solution deposition of Au NPs, and final thermal oxidization. SEM, TEM, EDX, XPS, and XRD analyses revealed that the interior cores and exterior shells of the as-prepared heteronanorods were single-crystal wurtzite-type ZnO and polycrystalline orthorhombic V2O5, respectively, with a large quantity of Au NPs inlaid in the V2O5 shell. The optical properties of the ternary photocatalyst were investigated in detail and compared with those of bare ZnO and V2O5@ZnO. UV-vis absorption spectra of ZnO, V2O5@ZnO, and Au-decorated V2O5@ZnO showed gradually enhanced absorption in the visible region. In addition, gradually decreased emission intensity was also observed in the photoluminescence (PL) spectra, revealing enhanced charge separation efficiency. Because of these excellent qualities, the photocatalytic behavior of the ternary photocatalyst was studied in the photodegradation of methylene blue under UV-vis irradiation, which showed an enhanced photodegradation rate nearly 7 times higher than that of bare ZnO and nearly 3 times higher than that of V2O5@ZnO, mainly owing to the enlarged light absorption region, the effective electron-hole separation at the V2O5-ZnO and V2O5-Au interfaces, and strong localization of plasmonic near-field effects.

A fluorescent probe for the detection of Hg2+: Shift from “on-state A” to “on-state B”

A simple pyrene based receptor has been synthesised and shown to exist in the dimeric form in solution exhibiting an excimer band in the emission spectrum. The proposed dimeric form is supported by the DFT calculations. Further, the excimer fluorescence is bathochromically shifted with decreased emission intensity in the presence of Hg2+ suggestive of the formation of an aggregated complex. The sensing event also worked on the solid support; thus attesting the potential of the sensor for practical application in contact mode.

The enhanced phosphorescence from Alq3 fluorescent materials by phosphor sensitization

Abstract The green emission accompanied with intense red phosphorescence is observed from the tris(8-hydroxyquinoline) aluminum (Alq 3 ) in the heavily doped tris(2-phenylpyridine) iridium [Ir(ppy) 3 ] films. This photoluminescence (PL) emission mechanism is studied by the PL excitation (PLE) spectra for the red and green emissions. From the PLE spectrum for the red emission, the energy transfer from Ir(ppy) 3 to Alq 3 is confirmed. The increase of the green emission with increasing temperature from 12 K is explained by the endothermic back Forster energy transfer from the triplet T 1 state of Ir(ppy) 3 to the singlet S 1 state of Alq 3 . It is suggested that this back transfer is partially responsible for the decrease of the red emission intensity corresponding to the increase of the green emission. Unlike the Forster energy transfer, the Dexter energy transfer from the T 1 state of Ir(ppy) 3 to the T 1 state of Alq 3 is highly efficient. The explanation for this process is presented here. The green emission is not attributed to Ir(ppy) 3 but to Alq 3 , because not only the green emission profile but also the red emission profile is quite similar to the δ-phase polycrystalline Alq 3 . From these results, it is concluded that the Alq 3 forms a δ-phase polycrystalline state to accept the phosphor sensitization. The unusual enhancement of the red phosphorescence from the Alq 3 is explained by the mixing of the T 1 state of Ir(ppy) 3 with the T 1 state of Alq 3 under the Dexter energy transfer of short range process, by taking into account that the T 1 state of Ir(ppy) 3 contains the singlet state by the strong spin–orbit coupling.

P‐179L: Late‐News Poster: Chemical Stability Enhancement of K2SiF6:Mn4+ by Metal (Oxide) Coating

AbstractThe K2SiF6:Mn4+ phosphor was synthesized by a redox reaction from SiO2 [1]. Under the 450 nm excitation, K2SiF6:Mn4+ show a narrow deep‐red emitting around 633 nm which attributed to the 2Eg to 4A2g transition of Mn4+ ion with the half width of 8 ‐10 nm. The particle size was approximately 8 μm. We obtained single phase of cubic structure with a space group of Fm‐3m (225) which agree with XRD pattern of JCPDS # 85‐1382. In the temperature dependence of emission spectra, emission intensity decrease to around 60 % (80%@200°C YAG) of that at room temperature is about 175°C. The chemical stability of the phosphors was improved by coating the phosphor with target metal oxide. These phosphors can be efficiently excited by the blue light‐emitting InGaN diode and provides a high color rendering property with green or yellow phosphors. It will be useful as a red phosphor for white‐light‐emitting diode.

Effect of synthesis conditions on the structural characteristics and luminescence properties of Y0.9Eu0.1V1−xCrxO4 (0 ≤ x ≤ 0.5) nanopowders

Y0.9Eu0.1V1−xCrxO4 (0 ≤ x ≤ 0.5) nanophosphors were synthesized under acid conditions (pH = 2) by a one-step sol–gel process followed by a thermal treatment at 843 K in oxygen flow. The obtained nanopowders were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and by Raman and photoluminescence (PL) spectroscopies in a confocal microscope. The influence of pH on the structural characteristics and luminescence properties of the nanophospors was also assessed. XRD measurements reveal a progressive loss of crystallinity as chromium substitutes for vanadium in the samples. Such replacement induces a progressive broadening of the Raman peaks as the Cr content increases, evidencing a certain structural distortion involving different (VO4)3− groups due to the insertion of Cr5+ ions into the host. TEM images of the obtained nanopowders show changes in the particle shape and size of samples grown a different pH values. The addition of chromium hampers an effective energy transfer from the vanadate groups to the Eu3+ ions. This results in a strong decrease of the PL emission intensity corresponding to the intraionic transitions of this rare earth, irrespective of the synthesis conditions of the nanopowders.

2.7 μm emission of Er3+-doped LiNbO3 crystals and its thermal effect

We have studied the 2.7 μm emission of singly Er3+-doped and Er3+/Dn+-codoped (Dn+ = Yb3+, Mg2+, Zn2+ and In3+) LiNbO3 crystals, as well as its thermal effect. The emission and absorption cross section spectra were calculated from the measured emission spectra. The results show that the peaking emission and absorption cross section values vary around 1 × 10−20 cm2 and increase slightly with the increased rare-earth ion concentration. The codoping of optical-damage-resistant ions Mg2+, Zn2+ and In3+ tends to reduce the cross section value. The different effects are related to the fact that the rare-earth/optical-damage-resistant ion doping induces successive increase/decrease of intrinsic defects, slight spectral broadening/narrowing of Er3+ absorption (emission) band, and hence slight increase/decrease of Er3+ absorption (emission). The thermal effect study shows that the peaking emission intensity decreases by ∼78% with the temperature rise of only 54 °C from 24 °C.

Improvement in a-plane GaN crystalline quality using wet etching method

Nonpolar (112̄0) GaN films are grown on the etched a-plane GaN substrates via metalorganic vapor phase epitaxy. High-resolution X-ray diffraction analysis shows great decreases in the full width at half maximum of the samples grown on etched substrates compared with those of the sample without etching, both on-axis and off-axis, indicating the reduced dislocation densities and improved crystalline quality of these samples. The spatial mapping of the E2 (high) phonon mode demonstrates the smaller line width with a black background in the wing region, which testifies the reduced dislocation densities and enhanced crystalline quality of the epitaxial lateral overgrowth areas. Raman scattering spectra of the E2 (high) peaks exhibit in-plane compressive stress for all the overgrowth samples, and the E2 (high) peaks of samples grown on etched substrates shift toward the lower frequency range, indicating the relaxations of in-plane stress in these GaN films. Furthermore, room temperature photoluminescence measurement demonstrates a significant decrease in the yellow-band emission intensity of a-plane GaN grown on etched templates, which also illustrates the better optical properties of these samples.

Diethyl (biscyclohexano)BODIPY dicarboxylates. Chelation of alkaline-earth metal ions and sensor properties

meso-Aryl-substituted (biscyclohexano)bis(ethoxycarbonyl)BODIPY [aryl = phenyl, 3,4-dimethoxyphenyl, and 2,3,5,6,8,9,11,12-octahydro-1,4,7,10,13-benzopentaoxacyclopentadecin-15-yl-(m-{benzo-15-crown-5}-yl)] were synthesized. The effect of alkaline-earth metals on the absorption and fluorescence spectra of these compounds was investigated. In all compounds along with the mechanism of the photoinduced electron transfer (PET), well-known for the crown-containing BODIPY-based sensors, one more response pattern is observed. The large excess of Ca2+ and Ba2+ ions in the system leads to the changes both in the UV-Vis and emission spectra. The complex formation results in the decrease of emission intensity and in its red shift. Besides, a new longwave absorption band appears in the UV-Vis spectrum of the BODIPY-metal ion complex. The formation constants of the complexes corresponding to this response pattern is about 100 times less than the formation constant of Ca2+-crown ether complex. 1H, 13C, 11B, and 19F NMR spectra, the results of quantum-chemical calculations, and their comparison with the literature data of X-ray diffraction study suggest that the binding of Ca2+ and Ba2+ ions occurs in the cavity formed by the fluorine atoms and the carbonyl oxygen atoms of the ester groups.

蛍光ランプと使用されるレアアース系蛍光体のランプ点灯による性能変化およびその関連性について

Deterioration of the performance of rare earth fluorescent lamps and phosphors after use, and these relationships were studied. In recent years, the demand of the recovery of valuable rare earth from used fluorescent lamps is increasing. However, recycling of rare earths is not progressing much because of the difficulty due to their chemical characteristics. On the other hand, recently, the reuse business of the materials recovered from used fluorescent lamps has begun in some places. Fluorescent lamps which are partially constructed from recycled materials are being slightly manufactured. Decrease in emission intensity of the phosphors was lower than that of fluorescent lamps. There are other factors such as consumption of mercury and emitter to reduce light quantity of the lamps. On the other hand, the main factor that decrease the emission intensity of the phosphors was concluded to contamination by adhesion of the emission materials made of lamp components, such as glass, mercury and emitter in this study. Although, chemical change, oxidation of the activator, and deterioration of the crystalline, those mean internal degradation of phosphor materials, were not significant. It is suggested that it becomes valid way to reuse the phosphors exhibiting a relatively high brightness, those are recovered from the fluorescent tubes cut off the portion surrounding the emitter, because the fouling by emitting substances is intense about that portion.

Data-driven discovery of energy materials: efficient BaM2Si3O10 : Eu2+ (M = Sc, Lu) phosphors for application in solid state white lighting.

In developing phosphors for application in solid state lighting, it is advantageous to target structures from databases with highly condensed polyhedral networks that produce rigid host compounds. Rigidity limits channels for non-radiative decay that will decrease the luminescence quantum yield. BaM(2)Si(3)O(10) (M = Sc, Lu) follows this design criterion and is studied here as an efficient Eu(2+)-based phosphor. M = Sc(3+) and Lu(3+) compounds with Eu(2+) substitution were prepared and characterized using synchrotron X-ray powder diffraction and photoluminescence spectroscopy. Substitution with Eu(2+) according to Ba(1-x)Eu(x)Sc(2)Si(3)O(10) and Ba(1-x)Eu(x)Lu(2)Si(3)O(10) results in UV-to-blue and UV-to-blue-green phosphors, respectively. Interestingly, substitution with Eu(2+) in the Lu(3+) containing material produces two emission peaks at low temperature and with 365 nm excitation, as allowed by the two substitution sites. The photoluminescence of the Sc(3+) compound is robust at high temperature, decreasing by only 25% of its room temperature intensity at 503 K, while the Lu-analogue suffers a large drop (75%) from its room temperature intensity. The decrease in emission intensity is explained as stemming from charge transfer quenching due to the short distances separating the luminescent centers on the Lu(3+) substitution site. The correlation between structure and optical response in these two compounds indicates that even though the structures are three-dimensionally connected, high symmetry is required to prevent structural distortions that could impact photoluminescence.

Structural and Photoluminescence Properties of Co-Doped ZnO Nanorods Prepared by RF-Magnetron Sputtering

Cobalt-doped ZnO nanorods were successfully synthesized on SiO2/Si substrate using RF-magnetron sputtering at room temperature. The structural, morphological, and photoluminescence (PL) properties of undoped and Co-doped ZnO nanostructure were characterized using X-ray diffraction, field emission-scanning electron microscopy, and PL analyses. The results showed that Co2+ replaces Zn2+ in the ZnO lattice without changing the wurtzite structure. As the Co concentration increases, the structure becomes highly crystalline and is gradually converted into nanorods with no extra phases. The as-synthesized nanorod arrays are dense and vertically grow on the SiO2 substrate. The arrays exhibit diameters of approximately 56.89 nm as well as lengths that range from 247.9 nm to 527.5 nm. PL analysis reveals that the ultraviolet (UV) emission intensity decreases and exhibits a blue shift as the Co doping level is increase.