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Radial Bragg gratings are commonly used to enhance light extraction from quantum emitters, but lack a well‐suited, fast simulation method for optimization beyond periodic designs. To overcome this limitation, an algorithm based on the transfer matrix model (TMM) to calculate the free‐space emission of such gratings is proposed and demonstrated. Using finite difference time domain (FDTD) simulations, free‐space emission, and transfer matrices of single grating components are characterized. The TMM then combines any number of components to receive the total emission. Randomized benchmarks verify that results from this method agree within 98% with FDTD while reducing simulation time by one to two orders of magnitude. The speed advantage of this approach is shown by maximizing emission of a fifteen‐trench circular grating into a Gaussian mode. It is expected that this novel algorithm will facilitate the optimization of radial gratings, enabling quantum light sources with unprecedented collection efficiencies. [ABSTRACT FROM AUTHOR]

• Toluene emissions from the returned wheat straw were investigated. • Toluene dominated in released VOCs from the returned wheat straw. • Toluene emissions preferred to flooded condition, mainly from secondary formation. • Over 90% of toluene emissions occurred between days 24-56 under flooded condition. • Straw return might be an essential source of biogenic toluene. As a common practice in agricultural system, straw return has been reported to release a large number of trace gases and attracted much attention. However, the role of straw return in toluene emission remains poorly understood. In this study we measured the emissions of toluene as well as other 50 volatile organic compounds (VOCs) from wheat straw return for 66 days under flooded and non-flooded conditions, respectively. The results showed that substantial toluene was released from the returned wheat straw particularly under flooded condition, and primarily derived from the secondary product. Toluene emissions from the returned wheat straw were 36.8 and 8.45 mg C/kg, sharing 28.0% and 8.6% of total VOCs released, and over 90% of toluene emissions occurred between days 24-56 and 0-17 under flooded and non-flooded conditions, respectively. The emission rates of toluene were relatively high but decreased sharply at the beginning 2 days, and then was steady until 24 days under the two moisture conditions. After the initial decrease these rose again to form one "peak emission window" between days 24-56 under flooded condition, while these were still very low and steady until the end under non-flooded condition. The toluene emission rates significantly positively correlated with microbial biomass C under flooded condition, but negatively associated with bacteria and fungus number, microbial biomass C, and CO 2 flux under non-flooded condition, suggesting that microorganism might play an important role in toluene emissions from wheat straw return. A rough estimate indicated that straw return might be important for biogenic toluene. [Display omitted]. [ABSTRACT FROM AUTHOR]

Light is known to exert radiation pressure on any surface it is incident upon, via the transfer of momentum from the light to the surface. In general, this force is assumed to be pushing or repulsive in nature. In this paper, we present a quantum treatment of radiation pressure. We show that the interaction of an atom with light can lead to both repulsive and attractive forces due to absorption and emission of photons, respectively. An atom prepared in the excited state initially will experience a pulling force when interacting with light. On the other hand, if the atom is prepared in the ground state then the force will be repulsive, while having the same magnitude as in the earlier case. Therefore, for an ensemble of atoms, the direction of the net force will be decided by the excited and ground state populations. In the semi-classical treatment of light-matter interaction the absorption and emission processes have the same probability, therefore the magnitudes of the force in the two processes turn out to be the same. We obtain the effective emission profile for an excited atom interacting with quantum electromagnetic field, and show that in the quantum treatment, despite these probabilities being different, the magnitudes of the statistical force remain the same. This can be explained by noting that the extra contribution in the emission process is due to the interaction of the atom with the vacuum modes of electromagnetic field, results in symmetric emission profile, contributing to a net zero force on the atoms in an ensemble. We further identify the set of states of electromagnetic field which give rise to non-zero momentum transfer to the atom.

A growing number of studies warn of the adverse health effects of indoor particulate matters (PM). However, little is known about the molecular compositions and emission characteristics of PM‐bound organics (OM) indoors, a critical group of species with highest concentration and complexity in indoor PM. In a Hong Kong residence where prescribed activities were performed with normal frequency and intensity, we found that the activities significantly elevated not only the total concentration but also the fraction of OM in indoor PM. However, the concentration of the total PM‐bound OM outdoors (10.3 ± 0.7 μg/m3) surpassed that for the indoor counterpart during the undisturbed period (8.2 ± 0.1 μg/m3), that is, period when there was no activity with high emission of PM but the residual effects of previous activities might remain. Emissions of indoor activities involving combustion or high‐temperature processes significantly elevated the indoor‐to‐outdoor (I/O) ratios for a majority of organic species. In addition, gas‐to‐particle partitioning, secondary formation, carrying‐over (residues of pollutants in the air), and re‐emission also modulated the I/O ratios of some compounds. Chemically comprehensive emission profiles of speciated organics were obtained for 5 indoor activities in the residence. While the indoor contribution to PM‐bound OM was estimated to be not higher than 13.1% during the undisturbed period, carrying‐over and/or re‐emission seemed to exist for certain compounds emitted from cigarette smoking and incense burning. This study enhances knowledge on emissions and airborne fate of speciated organics in indoor PM. [ABSTRACT FROM AUTHOR]

Morphological characteristics of Strong Thermal Emission Velocity Enhancement (STEVE) are investigated during an event on July 17, 2018. We calibrate photographs from citizen scientists for scientific purposes. We determine the altitude profiles for STEVE emissions. The spectral continuum purplish STEVE emission peaks at 200 km, which is in the altitude range where redline‐only SAR emission could be generated. The green picket fence peaks at 110 km, similar to that of the typical green aurora. For both emissions, their altitudes of the peak emissions and the shapes of the altitude profiles are similar across different longitudes. In regions of two‐layer purplish STEVE emissions, the lower layer STEVE peaks at ∼130 km with slightly different peak altitudes at different longitudes. The green picket fence structures are separated by 14 km in longitude with a full width of half maximum of ∼5.3 km. They move westward at a roughly constant speed of ∼250 m/s, although they sometimes disappear and reappear. The purplish STEVE and green picket fence emissions are latitudinally narrow, and whether they are simultaneously collocated on the same magnetic field line depends on their latitudinal offset relative to their width. We demonstrate that the green picket fence and purplish STEVE emissions are located on magnetic field lines within a tenth (0.02°) of the latitudinal width of STEVE (0.2°). The fact suggests that different STEVE emissions are driven by the same narrow region either in the ionosphere or the magnetosphere, although their generation mechanisms differ. The morphological characteristics have important implications in determining how STEVE is generated. Key Points: We obtain triangulated altitude profiles of upper and lower layer purplish Strong Thermal Emission Velocity Enhancement (STEVE) and green picket fence emissions as a function of longitudeThe peak altitudes of purplish STEVE emission (200 km) and green picket fence (110 km) do not change significantly across different longitudesSTEVE emissions map to a latitudinally narrow driver region along field line, with accuracy of one‐tenth of its latitudinal width [ABSTRACT FROM AUTHOR]

We demonstrated the way to improve the characteristics of quantum dot light emitting diodes (QD-LEDs) by adding a simple step to the conventional fabrication process. For instance, we can effectively deactivate the surface defects of quantum dot (QD) (e.g., CdSe/ZnS core-shell QDs in the current work) with the SiO bonds by simply mixing QDs with hexamethyldisilazane (HMDS) under atmospheric conditions. We observed the substantial improvement of device characteristics such that the current efficiency, the maximum luminance, and the QD lifetime were improved by 1.7–1.8 times, 15–18%, and nine times, respectively, by employing this process. Based on the experimental data (e.g., energy dispersive X-ray spectroscopy (EDX), and X-ray photoelectron spectroscopy (XPS)), we estimated that the growth of the SiOx on the surface of QDs is self-limited: the SiOx are effective to passivate the surface defects of QDs without deteriorating the intrinsic properties including the color-purity of QDs. Second, we proposed that the emission profiling study can lead us to the fundamental understanding of charge flow in each layer of QD-LEDs. Interestingly enough, many problems related to the charge-imbalance phenomenon were simply solved by selecting the combination of thicknesses of the hole transport layer (HTL) and the electron transport layer (ETL). [ABSTRACT FROM AUTHOR]

Thermal aging of natural ester oil shows drastic reduction in partial discharge inception voltage (PDIV) and a significant variation is observed only above a certain aging time, under AC, DC, high frequency AC voltages and with harmonic voltages with different total harmonic distortion. Weibull distribution studies on PDIV measurements indicate a reduction in scale parameter (α) with increase in thermal aging temperature. A characteristic reduction in breakdown voltage was observed with the thermally aged ester oil, under AC, DC and standard lightning impulse voltage. The breakdown voltage variation with aged ester oil follows normal distribution. Ultraviolet (UV) analysis of ester oil thermally aged at 160°C has revealed a regular shift of the derived absorbance parameter to longer wavelengths. The interfacial tension and turbidity exhibits an inverse relationship with the thermally aged ester oil. Gas chromatography/mass spectrometric analysis of the thermally aged ester oil predicted the formation of more carboxylic acids and ketones with aging duration. The steady-state fluorescence on thermally aged ester oil exhibits a shift in its emission profile, which is in tandem with the UV absorption spectroscopic analysis. Fluorescence analysis can be adopted as a real-time monitoring tool in transformers, to understand the condition of liquid insulation. The viscosity dependence on the wavelength of derivative absorption maxima follows a direct relationship with the thermally aged natural ester oil.

This review described a noticeable feature of pulsed radio-frequency-driven glow discharge plasma for atomic emission spectrometry. The temporal response of the emission signal, generated by the pulsed discharge, comprised a sharp pre-peak and the subsequent plateau portion having smaller emission intensities each for the discharge pulse, in which the intensity of the pre-peak was 10–20 times as large as the plateau-stage intensity, depending on the discharge parameters. Suggested mechanisms for this phenomenon were introduced from several published papers, which were based on a temporal variation in a degree of self-absorption during a pulse duration, on generation of gas pressure wave, or on a transient increase of the discharge current at the initial edge of a pulse which thus elevated the gas temperature. It was also mentioned that such emission characteristics could be utilized to obtain better analytical performance in the optical emission spectrometry. A detection method, associated with the introduction of pulsed bias current, was effective for controlling the emission response from the pulsed plasma, because it totally elevated the emission intensity of the plateau portion rather than the pre-peak with little change in the background level. [ABSTRACT FROM AUTHOR]

Energy use in rural areas in Nigeria is largely dependent on firewood and other biomass sources. Biomass fuel is domestically used daily for cooking and lighting. Continuous use of this energy resource has negative impact on both the environment and human health, especially on users. Many pulmonary problems have been associated with continuous exposure to smoke arising from burning of these materials. The use of briquetting is a more sustainable alternative to raw burning of biomass as briquettes burn with little or no smoke. However, there is scarcity of data on the emission profiles of major gaseous pollutants arising from many biomass briquettes. This study therefore, investigated the emission profiles of carbon monoxide (CO), carbon dioxide (CO2), sulphur dioxide (SO2) nitrogen dioxide (NO2) and particulate matter (PM2.5) from the combustion of unmodified as well as starch and paper modified briquettes made from four commonly used agro-based wastes namely, wood (control), sawdust (SD), rice husk (RH), coconut shell (CS) and corncob (CC). The gaseous pollutants emitted from combusting 0.5kg of each briquette were measured using appropriate devices. The mean concentrations (ppm) of gaseous emissions and particulates from all briquettes ranged as follows: CO: 35.4 - 79.0, CO2: 500 - 852, NO2: 0.09-0.50 and SO2: bdl - 2.13. All briquettes indicated higher PM2.5 concentrations than control (5190 µg/m3) except SD-paper modified briquettes (3305 µg/m3). CC-paper modified briquettes and RH-starch modified briquettes showed highest concentrations of 21003µg/m³ and 16362µg/m³, respectively. CS-paper modified briquettes emitted the least concentration of PM2.5. This suggests it could be considered as the safest and most ecofriendly of the briquette types. [ABSTRACT FROM AUTHOR]

Abstract Nitrated phenols (NPs) are regarded as a major component of brown carbon and affect the earth environment. Previous studies have suggested that NPs in the atmosphere partially originate from coal combustion; however, the direct emissions have not been validated. In this study, the emissions of ten NPs from ten kinds of coal for residential use were investigated via laboratory combustion experiments in which PM 2.5 samples were collected and analyzed by UHPLC-MS. The fine particulate NPs emitted from coal combustion were dominated by nitrocatechols and the methyl substituents under most conditions, while the emission profile of nitrated phenols varies with different rank of coals. Based on the emission ratios of NPs/PM 2.5 obtained from this study and the PM 2.5 emission factors in the literature, the emission factors of fine particulate NPs for chunks of lignite, bituminite, and anthracite and for briquettes of anthracite were calculated as 0.2–10.1 mg kg−1. According to the residential coal consumption in 30 provinces in China in 2016, the total emission of fine particulate NPs from the residential coal combustion was estimated to be 178 ± 42 Mg. Graphical abstract Image 1 Highlights • Emission profile of nitrated phenols varies with coal maturity and combustion stage. • Emission factor of nitrated phenols decreases with the increasing rank of coal. • Emission of nitrated phenols from residential coal combustion in China was estimated. [ABSTRACT FROM AUTHOR]

We demonstrated the way to improve the characteristics of quantum dot light emitting diodes (QD-LEDs) by adding a simple step to the conventional fabrication process. For instance, we can effectively deactivate the surface defects of quantum dot (QD) (e.g., CdSe/ZnS core-shell QDs in the current work) with the SiO bonds by simply mixing QDs with hexamethyldisilazane (HMDS) under atmospheric conditions. We observed the substantial improvement of device characteristics such that the current efficiency, the maximum luminance, and the QD lifetime were improved by 1.7–1.8 times, 15–18%, and nine times, respectively, by employing this process. Based on the experimental data (e.g., energy dispersive X-ray spectroscopy (EDX), and X-ray photoelectron spectroscopy (XPS)), we estimated that the growth of the SiOx on the surface of QDs is self-limited: the SiOx are effective to passivate the surface defects of QDs without deteriorating the intrinsic properties including the color-purity of QDs. Second, we proposed that the emission profiling study can lead us to the fundamental understanding of charge flow in each layer of QD-LEDs. Interestingly enough, many problems related to the charge-imbalance phenomenon were simply solved by selecting the combination of thicknesses of the hole transport layer (HTL) and the electron transport layer (ETL).

The objective of this paper is to suggest a new method for controlling temporal response of the emission signal from a pulsed radio-frequency (RF) glow discharge plasma for optical emission spectrometry. It is a noticeable feature that the emission profile accompanies a transient stage in the pulsed operation, appearing as a pre-peak which sometimes becomes 10–20 times as large as the plateau-stage intensity. Therefore, it is worth studying how the spike-like transient signal can be modified to a smooth response following the square-wave timing signal by using any experimental procedure. For this purpose, a phenomenon regarding self-bias voltage in RF plasma was focused on. The self-bias voltage is induced near the RF-loaded electrode, and then, a bias current can be introduced through an electric circuit including the plasma body by connecting an external electric device with the glow discharge plasma source. The bias current could be also pulsated, while it was synchronized with the pulsed RF plasma. Larger pulses of the bias current could change the characteristics of the plasma for atomic emission spectrometry, extending the size of the RF plasma as well as enhancing the emission intensity, which enabled the plateau stage to become more prominent in the pulsed emission profile. Several experimental parameters, such as an amplitude of the bias current, duty ratios of both the RF power and the bias current, and a phase shift between them, were investigated to obtain a plateau-like transient response of the emission signal. It was found that the phase-shift angle should be regulated between timing pulses of the RF voltage and the bias current. [ABSTRACT FROM AUTHOR]

Norway spruce ( Picea abies ) is one of the dominant tree species in the European boreal zone with the capacity to grow over large areas within Europe. It is an important emitter of biogenic volatile organic compounds (BVOCs), which can act as precursors of photochemical smog and ozone and contribute to the formation and growth of secondary organic aerosols (SOA) in the atmosphere. Isoprenoid emissions were measured from Norway spruce trees at seven different sites, distributed from Ljubljana in Slovenia to Piikkiö in Finland. Four of the sites were part of a network of genetically identical spruce trees and contained two separate provenances. The remaining three sites were part of other networks which have been used to conduct studies in the European boreal zone. There were minimal differences in the standardized emission rates between sites and across latitudes. The emission profile differed between provenances and sites, but there were not any distinct patterns which could be connected to a change in latitude. By using genetically identical trees and comparing the emission rates between sites and with genetically different trees, it was observed that the emission patterns were mostly influenced by genetics. But in order to confirm this possible stability of the relative emission profile based on genetics, more studies need to be performed. The effects of branch height, season and variation between years on observed emission pattern variations were also investigated. There were indications of potential influences of all three factors. However, due to different experimental setups between measurement campaigns, it is difficult to draw any robust conclusions. [ABSTRACT FROM AUTHOR]

The present study investigates the suitability of marine microalga Chlorella vulgaris BDUG 91771 biodiesel to curb the fuel crisis, based on engine performance and emission profile. Initially, biodiesel was produced from outdoor grown Chlorella vulgaris BDUG 91771 and its fuel properties accorded with ASTM D6571 and EN 14214 standards. To evaluate performance and emission characteristics, various Chlorella vulgaris BDUG 91771 biodiesel-diesel blends were prepared and tested in single-cylinder Kirloskar engine under four different load operations (0%, 50%, 75%, 100%). Compression ignition engine fuelled with B40 or B50 biodiesel-diesel blend showed specific fuel consumption (SFC), and brake thermal efficiency (BTE) of 0.306 kg/kWh and 26% respectively at 100% load, which is on par with diesel fuel. Further, engine operated with B50 biodiesel blend evidently reduced the carbon monoxide (CO) and hydrocarbon (HC) emissions by 0.1% and 102 ppm respectively compared to baseline diesel. Notably, diesel emitted 7.5% carbon dioxide (CO 2 ) and 380 ppm nitrogen oxides (NO x ) at 100% load, while the optimal blends B40 or B50 reduced CO 2 and NO x emissions by 6.1% and 376 ppm respectively. Based on results, present work suggests either B40 or B50 Chlorella vulgaris BDUG 91771 biodiesel – diesel blend could serve as eco-friendly, alternative fuel. [ABSTRACT FROM AUTHOR]

A one-axis charge-coupled device camera-based goniometer setup was developed to measure the three-dimensional radiance profile (longitudinal, azimuthal, and polar) of cylindrical light diffusers in air and water. An algorithm was programmed to project the two-dimensional camera data onto the diffuser coordinates. The optical system was designed to achieve a spatial resolution on the diffuser surface in the submillimeter range. The detection threshold of the detector was well below the values of measured radiance. The radiance profiles of an exemplary cylindrical diffuser measured in air showed local deviations in radiance below 10% for wavelengths at 635 and 671 nm. At 808 nm, deviations in radiance became larger, up to 45%, most probable due to the manufacturing process of the diffuser. Radiance profiles measured in water were less Lambertian than in air due to the refractive index matching privileging the radial decoupling of photons from the optical fiber. [ABSTRACT FROM AUTHOR]

Combustion of domestic solid fuels is a significant source of polycyclic aromatic hydrocarbons (PAHs). Some oxygenated PAHs (o-PAHs) and PAHs with molecular weight of 302 (MW302 PAHs) are more toxic than the traditional 16 priority PAHs, whereas their emissions were much less elucidated. This study characterized the size-dependent emissions of parent PAHs (p-PAHs), o-PAHs, and MW302 PAHs from various combustion sources. The estimated emission factors (eEFs) from biomass burning sources were highest for most of the PAHs (391–8928 μg/kg), much higher than that of anthracite coal combustion (43.0–145 μg/kg), both which were operated in an indoor stove. Cigarette smoking had a high eEF of o-PAHs (240 ng/g). MW302 PAHs were not found in the emissions of smoking, cooking, and vehicular exhausts. Particle-size distributions of PAHs were compound- and source-dependent, and the tendency to associate with smaller particles was observed especially in biomass burning and cigarette smoking sources. Furthermore, the inter-source differences in PAH eEFs were associated with their dominance in fine particles. PAH composition profiles also varied with the particle size, showing increasing contributions of large-molecule PAHs with decreasing sizes in most cases. The size distributions of p-PAHs are much more significantly dependent on their n-octanol/air partition coefficients and vapor pressures than those of o-PAHs, suggesting differences in mechanisms governing their distributions. Several molecular diagnostic ratios (MDRs), including two based on MW302 PAHs, specific to these combustion scenarios were identified. However, the MDRs within some sources are also strongly size-dependent, providing a new explanation for the uncertainty in their application for source identification of PAHs. This work also highlights the necessity for understanding the size-resolved atmospheric behaviors and fate of PAHs after their emission. • High EFs of PAHs from biomass burning and o-PAHs from cigarette smoking are found. • The particle-size distributions of PAHs are compound- and source-dependent. • PAH compositions from various biomass burning sources were generally similar. • PAH particle-size distributions are governed by their K OA and vapor pressure. • The molecular diagnostic ratios from combustion are also particle size-dependent. [ABSTRACT FROM AUTHOR]

Light is known to exert radiation pressure on any surface it is incident upon, via the transfer of momentum from the light to the surface. In general, this force is assumed to be pushing or repulsive in nature. In this paper, we present a quantum treatment of radiation pressure. We show that the interaction of an atom with light can lead to both repulsive and attractive forces due to absorption and emission of photons, respectively. An atom prepared in the excited state initially will experience a pulling force when interacting with light. On the other hand, if the atom is prepared in the ground state then the force will be repulsive, while having the same magnitude as in the earlier case. Therefore, for an ensemble of atoms, the direction of the net force will be decided by the excited and ground state populations. In the semi-classical treatment of light-matter interaction the absorption and emission processes have the same probability, therefore the magnitudes of the force in the two processes turn out to be the same. We obtain the effective emission profile for an excited atom interacting with quantum electromagnetic field, and show that in the quantum treatment, despite these probabilities being different, the magnitudes of the statistical force remain the same. This can be explained by noting that the extra contribution in the emission process is due to the interaction of the atom with the vacuum modes of electromagnetic field, results in symmetric emission profile, contributing to a net zero force on the atoms in an ensemble. We further identify the set of states of electromagnetic field which give rise to non-zero momentum transfer to the atom. [ABSTRACT FROM AUTHOR]

• Magnesium (II) metal chelates with heterocyclic moiety containing N, O donor atoms have been synthesized by conventional reflux method. • Prepared light emissive materials were analyzed in context of their structural, thermal, emission, colorimetric and theoretical approach. • Discrepancy in the temperature altered the position and the intensity of emission profile of metal complexes in solid state. • Electronic band gap computed via the theoretical and experimental approaches shows satisfactory agreement. • Color coordinates and CCT values replicates their pertinency in numerous advanced photonic and display devices. In present communication, light emissive magnesium (II) metal chelates with heterocyclic moiety containing N, O donor atoms have been synthesized by conventional reflux method. Structural, spectroscopic and optical analysis of prepared materials i.e., (pyridine-1-oxide)(8-quinolinato)magnesium(II) [Mg(PNO)(q)] and (2-hydroxypyridine-1-oxide)(8-quinolato)magnesium(II) [Mg(PHNO)(q)] have also been scrutinized through various spectral techniques. Thermal studies of synthesized materials were explored via execution of thermogravimetric (TG) and differential thermal (DT) analysis using thermal analyser at controlled heating rate. Electroanalytic measurements were demonstrated through cyclic voltammetry (CV) using three-electrode system. Optical band gap (E g) was deduced from absorption spectra of metal complexes using Tauc's method. Photoluminescence (PL) studies were conceded out in both solid and solution phase. Effect of temperature on emission profile of metal complexes was also illustrated. Three-dimensional (3D) molecular structures were geometrically optimized by means of B3LYP scheme comprising 6–31G* (d, p) cartesian-gaussian polarization with aid of theoretical computation (DFT). Moreover, emission profile was exploited to obtain required CIE constrain (CCT and color coordinates) which robustly recommendatory for their use in advance photonic applications and fabrication of light emitting devices. [Display omitted] Highlights [ABSTRACT FROM AUTHOR]

This work presents novel Capacitive Micromachined Ultrasonic Transducers (CMUTs) and their characterization in terms of ultrasound directionality. The devices are formed by 27 membranes, integrated on the same die and connected in parallel, featuring a 1 μm gap between the membrane and the bottom electrode, and directly coupling to air at 2.23 MHz. Exploiting the information on the amplitude and delay of the received ultrasonic waves, a directionality profile showing a 14° full width at half maximum (FWHM) and a 0.5-5 cm distance operative range are demonstrated. Object localization experiments show a 2D relative position reconstruction error around 5%. [ABSTRACT FROM AUTHOR]

Abstract: We present a comprehensive model to simulate organic light-emitting devices (OLEDs) that includes a seamless coupling of charges, excitons and photons. The comprehensive model accounts for the position dependent exciton lifetime due to the optical environment in the multilayer OLED structures. We first study the effect of different charge mobilities and quantum efficiencies of the light-emitting material on the exciton profiles. Moreover, we discuss the extension of an optical model to account for the exciton dynamics. This comprehensive optical model is validated and justified on the basis of consistency checks. Namely, we show that our comprehensive optical model can take the cavity effects as seen in simulation results of the comprehensive electrical model into account. The advantage of the comprehensive optical model is a quick and accurate insight into the exciton physics if applied together with a nonlinear least square (NLSQ) fitting method. Finally, we apply the comprehensive optical model with the NLSQ-method in order to extract the exciton profiles from emission spectra of a blue light-emitting polymer diode (PLED) measured at different current levels. [Copyright &y& Elsevier]

Abstract: Radiofrequency glow discharge coupled to optical emission spectroscopy has been used in pulsed mode in order to perform a detailed study of the measured temporal emission profiles for a wide range of copper transitions. Special attention has been paid to the early emission peak (or so-called pre-peak), observed at the beginning of the emission pulse profile. The effects of the important pulse parameters such as frequency, duty cycle, pulse width and power-off time, have been studied upon the Cu pulse emission profiles. The influence of discharge parameters, such as pressure and power, was studied as well. Results have shown that the intensity observed in the pre-peak can be 10 times as large as the plateau value for resonant lines and up to 5 times in case of transitions to the metastable levels. Increasing pressure or power increased the pre-peak intensity while its appearance in time changed. The pre-peak decreased when the discharge off-time was shorter than 100μs. According to such results, the presence of the pre-peak could be probably due to the lack of self-absorption during the first 50μs, and not to the ignition of the plasma. Under the selected operation conditions, the use of the pre-peak emission as analytical signals increases the linearity of calibration curves for resonant lines subjected to self-absorption at high concentrations. [Copyright &y& Elsevier]

Atmospheric PM pollution from traffic comprises not only direct emissions but also non-exhaust emissions because resuspension of road dust that can produce high human exposure to heavy metals, metalloids, and mineral matter. A key task for establishing mitigation or preventive measures is estimating the contribution of road dust resuspension to the atmospheric PM mixture. Several source apportionment studies, applying receptor modeling at urban background sites, have shown the difficulty in identifying a road dust source separately from other mineral sources or vehicular exhausts. The Multilinear Engine (ME-2) is a computer program that can solve the Positive Matrix Factorization (PMF) problem. ME-2 uses a programming language permitting the solution to be guided toward some possible targets that can be derived from a priori knowledge of sources (chemical profile, ratios, etc.). This feature makes it especially suitable for source apportionment studies where partial knowledge of the sources is available. In the present study ME-2 was applied to data from an urban background site of Barcelona (Spain) to quantify the contribution of road dust resuspension to PM10 and PM2.5 concentrations. Given that recently the emission profile of local resuspended road dust was obtained (Amato, F., Pandolfi, M., Viana, M., Querol, X., Alastuey, A., Moreno, T., 2009. Spatial and chemical patterns of PM10 in road dust deposited in urban environment. Atmospheric Environment 43 (9), 1650–1659), such a priori information was introduced in the model as auxiliary terms of the object function to be minimized by the implementation of the so-called “pulling equations”. ME-2 permitted to enhance the basic PMF solution (obtained by PMF2) identifying, beside the seven sources of PMF2, the road dust source which accounted for 6.9 μg m−3 (17%) in PM10, 2.2 μg m−3 (8%) of PM2.5 and 0.3 μg m−3 (2%) of PM1. This reveals that resuspension was responsible of the 37%, 15% and 3% of total traffic emissions respectively in PM10, PM2.5 and PM1. Therefore the overall traffic contribution resulted in 18 μg m−3 (46%) in PM10, 14 μg m−3 (51%) in PM2.5 and 8 μg m−3 (48%) in PM1. In PMF2 this mass explained by road dust resuspension was redistributed among the rest of sources, increasing mostly the mineral, secondary nitrate and aged sea salt contributions. [Copyright &y& Elsevier]

Receptor modelling techniques are used to identify and quantify the contributions from emission sources to the levels and major and trace components of ambient particulate matter (PM). A wide variety of receptor models are currently available, and consequently the comparability between models should be evaluated if source apportionment data are to be used as input in health effects studies or mitigation plans. Three of the most widespread receptor models (principal component analysis, PCA; positive matrix factorization, PMF; chemical mass balance, CMB) were applied to a single PM10 data set (n=328 samples, 2002–2005) obtained from an industrial area in NE Spain, dedicated to ceramic production. Sensitivity and temporal trend analyses (using the Mann–Kendall test) were applied. Results evidenced the good overall performance of the three models (r 2>0.83 and α>0.91×between modelled and measured PM10 mass), with a good agreement regarding source identification and high correlations between input (CMB) and output (PCA, PMF) source profiles. Larger differences were obtained regarding the quantification of source contributions (up to a factor of 4 in some cases). The combined application of different types of receptor models would solve the limitations of each of the models, by constructing a more robust solution based on their strengths. The authors suggest the combined use of factor analysis techniques (PCA, PMF) to identify and interpret emission sources, and to obtain a first quantification of their contributions to the PM mass, and the subsequent application of CMB. Further research is needed to ensure that source apportionment methods are robust enough for application to PM health effects assessments. [Copyright &y& Elsevier]

Abstract: In situ emission profiles of AlGaInP multiple quantum well laser diodes (LD''s) observed by a near-field scanning optical microscope (NSOM) probe with an intentionally enlarged aperture shows a single broad elliptic profile, whereas the detected wavelength hops among those of the longitudinal multimodes observed in the far-field. This hopping suggests the near-field coupling between the aperture and the LD cavity, which is proved by the observation of strong modulation of laser intensity by the optical coupling only in the near-field regime. Probes with an intact aperture are found not to couple with the lasing TE00 mode, but, therefore, couple only with a near-field longitudinal mode. Around the lasing region, emissions detected by an intact aperture are ascribed to amplified spontaneous emissions located at wavelengths far from those of the lasing multimode emissions. These near-field modes, with spatial profile different from both the far-field TE- and TM-modes, are detectable only by the NSOM. [Copyright &y& Elsevier]

Abstract: This paper presents a fine particle emission profile for a large metallurgical coke production facility. The profile is developed from highly time-resolved, ambient air quality measurements made at a fence line site adjacent to the plant. A fence line approach was employed because the coke plant has hundreds of stacks and other emission points, making it difficult to develop an integrated, facility-wide emission profile using stack sampling techniques. Continuous or semi-continuous measurements of PM2.5 mass, PM10 mass, SO2, NO x , organic and elemental carbon (OC and EC), particle size and number, 11 trace metals, wind direction and wind speed were made. Background pollutant levels were also measured. A combination of highly time-resolved meteorology and air quality data were used to determine when the coke facility emissions influenced the sampling site. Concentrations for most pollutants at the fence line site were one to two orders of magnitude higher than background levels when the facility plume heavily influenced the fence line site. Highly time-resolved measurements are essential to resolve these relatively short-duration, large spikes in pollutant concentrations. Simply measuring wind direction is insufficient. From these highly time-resolved measurements an average PM2.5 emission profile for the coke facility was developed. The profile is dominated by OC (40%±9% of PM2.5 mass emissions) and EC (25%±5% of PM2.5 mass emissions). Significant contributions of certain trace metals were also observed, including As, Zn, Se, and Pb. The particle emissions are dominated by the fine fraction, with PM2.5 estimated to contribute 84%±14% of the PM10 mass. [Copyright &y& Elsevier]

Abstract: The emissions of polycyclic aromatic hydrocarbons (PAHs) were quantified for two joss paper furnaces burning two kinds of joss papers (recycled paper made and virgin bamboo made). A cyclone and a wet scrubber were installed in series on one of the two furnaces. Particulate and gaseous PAHs were collected with a sampling system meeting the criteria of U.S. EPA Modified Method 5. Twenty-one species of PAH were analyzed by GC/MS. Individual PAH emission factors vary from less than 1mgkg−1 fuel to several tens of mgkg−1 fuel. The total (sum of 21 compounds) and the carcinogenic PAH (benz[a]anthracene, chrysene, benzo[b]fluoranthene, benzo[k]fluoranthene, benzo[a]pyrene, indeno[1,2,3,-cd]pyrene, dibenz[a,h]anthracene) emission factors were not statistically different for the two furnaces and averaged 71.0 and 3.2mgkg−1, respectively. The PAH profiles showed a predominance of naphthalene (58.1%), phenanthrene (11.7%) and fluorene (7.5%). Of the two joss papers examined, bamboo-made joss paper showed less emission in both particulate and gaseous PAHs. For particulate and gaseous PAHs, the removal efficiencies of total PAHs by the air pollution control devices were 42.5% and 11.7%, respectively. PAH emission factors in high airflow conditions were generally lower than those in low airflow condition. [Copyright &y& Elsevier]

The reheating furnace operation in the hot mill is natural gas- and electricity-intensive. Oxygen enrichment combustion for reheating furnaces has been proposed to curb and replace natural gas use. In this study, heat transfer in steel slabs in the combustion environment of a push-type reheating furnace was simulated using a computational fluid dynamics (CFD) model. Two oxygen enrichment methods that optimized for performance were selected— a medium oxygen enrichment (MOE) case and an oxy-fuel (OF) case. A life cycle analysis (LCA) characterized the energy and emission profiles of an integrated iron and steel manufacturing process using the two oxygen enrichment cases for the hot mill. These conditions were evaluated for energy use and carbon intensity and compared with a baseline case. Results show that with oxygen enrichment, natural gas consumption can decrease by 19.6%–26.8%, total energy consumption (natural gas and electricity) can decrease by 15.1%–20.7% in the hot mill. Emissions of greenhouse gases can decrease by 11.1%–15.2% in the two optimized cases with 14%–27% reductions in regulated criteria pollutants (nitrogen oxides, carbon monoxide, particulate matter, volatile organic compounds, black carbon, organic carbon, and volatile organic carbons). There is a tradeoff between reducing natural gas consumption and increasing electricity demand from a life cycle perspective. Although the OF case resulted in higher energy- and emissions-related benefits, the MOE case showed the more desirable heat flux uniformity, which is key to maintaining product quality. The analysis suggests that oxygen enrichment in the reheating furnace process can have a significant impact on hot mill environmental performance and become a contributing factor in transitioning to low-carbon steel manufacturing. • Oxygen enrichment in reheating furnace for producing hot rolled steel is simulated. • Reduction of fossil energy use by 20.7% and GHG emission by 15.2% in hot mills. • NO x , CO, VOC, PM 10 , PM 2.5 BC, and OC emissions decrease 14%–27% in hot mills. • Heat available for combustion in the reheating furnace doubled. • Electricity use increases in hot rolled steel life cycle. [ABSTRACT FROM AUTHOR]

. Cylindrical light diffusers are commercially available for clinical applications such as photodynamic therapy (PDT) and interstitial laser photocoagulation (ILP). A fluorescence imaging technique has been used to quantify the light distribution produced by each of six different diffuser fibres. The light distribution produced by each device was found to depend on the distance the light propagated in the fluorescent dye solution. At a distance of 1 mm from the diffuser midline, the measured profiles were found to be consistent with published results obtained in air at a similar distance. The three devices intended for PDT utilised scattering particles and reflectors in their construction. The profiles produced by these applicators revealed peaks that were attributed to the reflectors located at their distal tips. By comparison, the two etched ILP fibres displayed either a strong modulation in the profile due to non-uniform etching or a predominant forward peak associated with the conical shape of the tip. We conclude that it is important to take into account the forward-directed light emitted by the diffusers when considering clinical applications using these devices. [ABSTRACT FROM AUTHOR]

The uniformity of the emission profile produced by a cylindrical light diffuser is an important parameter for determining the light dose received by the target tissue during laser therapies such as photodynamic therapy (PDT) and interstitial laser photocoagulation (ILP). A technique originally used for determining the profile of a laser beam with a commercial video camera is adapted in order to measure the distribution of light from a cylindrical diffuser. The method can produce quantitative one-dimensional beam profiles in both the circumferential and axial direction of the light diffuser. The system allows the use of tissue phantoms that provide a convenient and effective method for comparing manufacturer's measurements often made in air with those to be expected in vivo. The technique is a quick and easy method for assessing light diffusers before treatment, and utilises readily available equipment that does not require specialist knowledge. Also, the response of the video camera facilitates the assessment of diffusers over a relatively broad optical spectrum, which encompasses the range of wavelengths currently used for both PDT (515–675 nm) and ILP (800–1064 nm). [ABSTRACT FROM AUTHOR]

Abstract: In situ emission profiles of AlGaInP multiple quantum well laser diodes (LDs) observed by a near-field scanning optical microscope (NSOM) probe with an intentionally enlarged aperture shows a single broad elliptic profile, whereas the detected wavelength hops among those of the longitudinal multimodes observed in the far-field. This hopping suggests the near-field coupling between the aperture and the LD cavity, which is proved by the observation of strong modulation of laser intensity by the optical coupling only in the near-field regime. Probes with an intact aperture are found not to couple with the lasing TE00 mode, but, therefore, couple only with a near-field longitudinal mode. Around the lasing region, emissions detected by an intact aperture are ascribed to amplified spontaneous emissions at wavelengths far from those of the lasing multimode emissions. These near-field modes, with spatial profile different from both the far-field TE and TM modes, are detectable only by the NSOM. [Copyright &y& Elsevier]