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The purpose of this study was to investigate the nasal absorption rate and nasal mucosal toxicity of thermosensitive ketamine in situ gels containing various absorption enhancers. The optimal compo...

Stability, robustness, sensitivity, and reproducibility are important parameters in the interferometry. We propose a wavefront splitting fiber Mach–Zehnder interferometer (MZI) to achieve such performances. A polyethylene terephthalate (PET) film splits the wavefront of a Gaussian beam emitted from the first fiber collimator. Then, the Gaussian beam is focused into a single mode fiber by another collimator, constituting a stable and robust fiber MZI. The effective spectral width is larger than 390 nm, which is wide enough for constructing a sensitive fiber MZI. The COMSOL multiphysics simulation and the experimental results demonstrate that this MZI is based on the multi-beam interference. Thanks to the low insertion loss of the fiber MZI, two types of stable and repeatable interference fringes are obtained when the sampling accuracy of the optical spectrum analyzer is as high as 0.1 nm. It ensures that the fiber sensor based on this MZI has a high resolution. For the first type of interference fringe, the two adjacent resonant wavelengths, respectively, shift –0.78 and –0.81 nm when salinity increases one part per thousand, showing high sensitivities. The low order interference fringe has a larger sensitivity. However, its visibility may be small due to the modulation of the second type of interference fringe that has small sensitivity to the refractive index of the sample. Since the PET film has uniform thickness, the fiber MZI can ensure good reproducibility. It can be widely utilized in detecting physical, chemical, or biological quantities.

The refractive index (RI) of atmospheric aerosols is a critical parameter in aerosol direct radiative forcing (DRF) calculation that exhibits considerable uncertainties owing partly to substantial spatiotemporal changes in the RI. A tandem system comprising a single-particle soot photometer connected to a differential mobility analyzer is developed. Two field campaigns are conducted to derive the size-resolved real part of the RI of scattering (i.e., BC-free) particles at 1064 nm (RRIsp1064nm) in urban Beijing. Measurements of the RRIsp1064nm within a mobility diameter (Dmob) range of approximately 200 nm to 400 nm in summer and winter clearly show seasonal variations in the RRIsp1064nm, including magnitude and size dependence. A decreasing RRIsp1064nm trend is observed in summer as the Dmob enlarges from 237 nm to 422 nm, whereas the RRIsp1064nm increases in winter as the Dmob grows. This finding likely indicates varying aerosol physicochemical properties with particle size in summer and winter. Size-resolved RRIsp1064nm values within the Dmob range are generally larger in summer than in winter, thereby resulting in a larger bulk RRIsp1064nm of 1.50 ± 0.01 in summer compared with winter (1.47 ± 0.02). The low RRIsp1064nm in winter is likely attributable to the high contribution of organic aerosols (OA), particularly less oxidized OA, which generally have lower RRI values than secondary inorganic aerosols. Pronounced low RRIsp1064nm values are observed during polluted episodes in winter, implying significant OA contribution. Photooxidation is likely an important regulator of the RRIsp1064nm in summer. This inference is supported by the fact that RRIsp1064nm values in the afternoon are larger than those at night, which corresponds well to diurnal variations in Ox (Ox=O3+NO2) concentrations. Results indicate that seasonal variations in the RRIsp1064nm should be considered carefully in research, such as in DRF assessments, aerosol property parameterization in chemical models, and aerosol optical property and composition remote sensing. Copyright © 2021 American Association for Aerosol Research

Black carbon (BC) is the most important aerosol light-absorbing component, and its effect on radiation forcing is determined by its microphysical properties. In this study, two microphysical parameters of refractory BC (rBC), namely, size distribution and mixing state, in urban Beijing from 2013 to 2019 were investigated to understand the effects of source changes over the past years. The mass equivalent diameter of rBC (Dc) exhibited bimodal lognormal distributions in all seasons, with the major modes accounting for most (>85%) of the rBC masses. The mass median diameter (MMD) was obviously larger in winter (209 nm) than in summer (167 nm) likely due to the contribution of more rBC with larger Dc from solid fuel combustion and enhanced coagulation of rBC in polluted winter. More rBC particles were thickly coated in winter, with the number fraction of thickly coated rBC (fcoatBC) ranging within 29%–48% compared with that of 12%–14% in summer. However, no evidential increase in BC light-absorption capability was observed in winter. This finding was likely related to the lower absorption efficiency of larger rBC in winter, which partly offset the coating-induced light enhancement. Two stage of decreases in MMD and fcoatBC were observed, accompanied with a persistent decrease in rBC loading, thereby reflecting the discrepant effects of source control measures on rBC loading and physical properties. The control measures in the earlier stage before 2016 was more efficient to reduce the rBC loading but slightly influenced the microphysical properties of rBC. As of 2016, the reduction in rBC concentration slowed down because of its low atmospheric loading. However, rBC showed a more obvious decrease in its core size and became less coated. The decrease in fcoatBC may have weakened the BC absorption and accelerated the decrease in light absorption resulting from the reduction in rBC loading.

We demonstrate an optical fiber magnetic field sensor that can measure both magnetic field intensity and directions. It is designed by immersing a microfiber into magnetic fluid (MF) and based on the light polarization detection. When there is external magnetic field, the magnetic nanoparticles of MF generate a noncircular symmetric distribution around the microfiber, and MF exerts magneto-optical dichroism. Light will be polarized after passing through the microfiber. The time response of the fiber magnetic field sensor is studied. It is found that the intensity of the magnetic field can be measured directly only when it satisfies the detectable threshold condition. Furthermore, the magnetic field sensor possesses good orientation response to the magnetic field directions. The signal analysis system consists of a polarization beam splitter and two photodetectors. The sensor designed has the advantages of both simple structure and low cost, without needing any precise spectral analyzer.

A real-time wavelength scanning distance interferometry is proposed. The interference signal generated by the light wavelength modulation is transformed into preliminary conversion signal with the two summarized waveform transformation laws. Inflection points of the interference signal are retrieved with two complementary methods which are discontinuity point judgment (DPJ) and the adjacent null points distance judgment (ANPDJ). Based on the preliminary conversion signal and the retrieved inflection points, the orthogonal signal is constructed. Displacement is calculated after demodulating the phase shift with the orthogonal demodulation algorithm. When millimeters distance is measured, the fluctuation of the measured result is around micrometers in about one hour. The measurement complexity and cost are all decreased, while, ideal measurement results can still be obtained. The approach can be used in a multitude of applications.

Knowledge of aerosol hygroscopicity is essential to assess visibility improvement and aerosol radiative forcing. Aerosol hygroscopicity is highly dependent on emission sources, while the hygroscopicity of different sources remains largely unexplored. In the current study, the hygroscopic growth factor (i.e., f(RH)) and relevant chemical compositions (e.g., water-soluble inorganic ions, carbonaceous fractions and elements) in fine particles were synchronously measured for nearly 3 months within 2019–2020 in an urban site of Guangzhou. The mean value (± standard deviation) of f(RH) at 70% RH was 1.50 (± 0.11). The diurnal cycle in aerosol hygroscopic growth strongly depended on the mass fraction of hydrophilic chemical compositions (e.g., SO42−, NO3− and NH4+) in fine particles and variation in contributions of aerosol sources. A Positive Matrix Factorization model was applied to distinguish the different hygroscopicity of specific source factors in a mixed aerosol. Secondary nitrate and secondary sulfate were more hydrophilic, whereas emissions from primary combustion processes (i.e., ship emission, coal combustion and road traffic) were less hygroscopic. Soil dust was almost insoluble. The hygroscopic growth of each source was parameterized that quantified the emission sources and f(RH) relationship for use of air quality and radiative transfer models either as input or as validation.

Computational ghost imaging (CGI) provides an elegant framework for indirect imaging, but its application has been restricted by low imaging performance. Herein, we propose a novel approach that significantly improves the imaging performance of CGI. In this scheme, we optimize the conventional CGI data processing algorithm by using a novel compressed sensing (CS) algorithm based on a deep convolution generative adversarial network (DCGAN). CS is used to process the data output by a conventional CGI device. The processed data are trained by a DCGAN to reconstruct the image. Qualitative and quantitative results show that this method significantly improves the quality of reconstructed images by jointly training a generator and the optimization process for reconstruction via meta-learning. Moreover, the background noise can be eliminated well by this method.

Regional transport and chemical conversions are two major processes that lead to the severe haze pollution in China. Our observations during five haze episodes in Beijing between February 19 and March 12 of 2014 show that the two processes played different roles as PM2.5 increased from the clean ( 250 μg m− 3) pollution. In the initial twelve hours of each episode, the PM2.5 reached the light-medium level with an increase of approximately 120 μg m− 3. At the same time, the particle (~ 10–700 nm) number concentration also showed a distinct increase accompanied by a rapid increase in the mean diameter. A light-medium PM2.5 occurred in the south areas prior to the haze occurrence in Beijing and the southerly winds were predominant, indicating the rapid increase of PM2.5 in the initial stage was caused by the regional transport from the south. Subsequently, PM2.5 elevated to the heavy and severe levels when the wind was weak, relative humidity was high and ozone concentration was low. The increase of PM2.5 in the elevated stages was characterized by a high percentage (45% for the heavy level and 55% for the severe level) of secondary inorganic components, indicating the substantial contribution of the formation of secondary aerosols. In addition, the increases of the mean diameter (from 108 nm to 120 nm) and the total volume concentration (by 67%) are regarded as a consequence of heterogeneous reactions on the surfaces of aerosol particles because the particle number concentration remained nearly constant in these two stages. Our results indicate that, during the five winter haze episodes, the regional transport from the south was the major reason for the initial-stage PM2.5 increase, while heterogeneous reactions dominated the later elevation.

To evaluate the impact of fine particulate matter (PM2.5) size distribution on aerosol chemical and optical properties, dominant chemical components including water-soluble inorganic ions (WSII), organic carbon (OC) and elemental carbon (EC) in PM1 and PM2.5, aerosol scattering coefficient (bsp), and aerosol absorption coefficient (bap) were collected synchronously at an urban site in Guangzhou, south China during a typical summer month in 2009 and a winter month in 2010. PM1 (sizes smaller than 1 μm) constituted 77% and 63% of PM2.5 in summer and winter, respectively. From the reconstructed mass concentrations, the sum of SO42 −, NO3− and NH4+ (SNA) distributed more in PM1 than in PM1–2.5 (PM2.5 minus PM1) in summer and the opposite was found in winter, while carbonaceous aerosols distributed more in PM1 in both summer and winter. With the aggravation of PM2.5 pollution, the mass fraction of PM1/PM2.5 increased for (NH4)2SO4 (AS), NH4NO3 (AN) and EC but decreased for organic matter (OM) in summer, and the opposite was found in winter. Bsp of PM1 and PM1–2.5 was estimated from the mass extinction efficiencies (MSEs) of the dominant chemical components, which showed good correlations (R2 = 0.99) with measured ones and those estimated using the IMPROVE formula. The fractional contributions of dominant chemical components to extinction coefficient (bext) were consistent with their respective mass size distributions, indicating the importance of chemically-resolved aerosol size distributions on aerosol optical properties and haze formation.

Black carbon (BC), which is a by-product with incomplete combustion of carbonaceous materials, can be used as an indicator of combustion emissions and is an important climate forcer. In this study, a spatial-temporal synthesis of BC aerosols and the affecting factors was conducted in urban Beijing. As observed, BC showed a spatial pattern with high concentration in south and low in north. BC concentration evidently decreased by approximately 61% between 2005 and 2017. From 2015 to 2017, the mass ratio of BC/PM2.5 dropped by 28%, which suggested a more efficient effect of control measures to BC than PM2.5. The BC/CO ratio dropped by 22%, which indicated the decreasing emission from fossil fuel sources. With regard to BC loading, the spectral dependence of absorption aerosol exhibited significant seasonal variations. High absorption Angstrom exponent (α) was observed during heating season, which reflected the increasing contribution of brown carbon (BrC) to light absorption. Backward trajectory analysis showed that the levels of BC and PM2.5 were high in Cluster-South and Cluster-West. BrC absorption was high in Cluster-West, Cluster-Northwest and Cluster-Northeast, due to the biomass and coal burning for domestic heating and aging processes on a regional scale. The effects of emission control and transport variability on pollutant variation were estimated on the basis of the cluster analysis. Results indicated that the effect of emission reduction was the major reason for the decrease of BC from 2015 to 2017, which resulted in a 34% reduction of BC concentration. Meanwhile, transport variability caused a 15% reduction.

Magnetic photonic crystal slab with nanovoids buried in Ni films were fabricated using nanosphere lithography combined with electrochemical deposition. One featured structure was dominated the spectra of polar surface magneto-optical Kerr effect (MOKE) of samples with different voids depth. For the shallow ones, surface lattice resonance (SLR) was revealed through angle resolved spectra analysis, where the location of degeneracy points corresponded to that of the featured structure in MOKE signal. For the deeper ones, localized plasmons and degeneracy points were all demonstrated in angle resolved reflection spectra, where localized plasmons dominated the resonant MOKE signal, and the degeneracy points blue-shifted compared with that of shallow ones. Changing the lattice of samples, similar phenomena were presented. The physical mechanism of SLR could be attributed to the diffraction of surface plasmons by the reciprocity vector, and the localized plasmons were attributed to the Mie scattering. The featured structure in polar MOKE spectra demonstrated high sensitivity, which might pave the way to on-chip MO devices.

Daily PM 2.5 samples were collected at an urban site in Guangzhou in 2014 and at a suburban site in Zhuhai in 2014–2015. Samples were subject to chemical analysis for various chemical components including organic carbon (OC), element carbon (EC), major water-soluble inorganic ions, and trace elements. The annual average PM 2.5 mass concentration was 48 ± 22 μg m − 3 and 45 ± 25 μg m − 3 in Guangzhou and Zhuhai, respectively, with the highest seasonal average concentration in winter and the lowest in summer at both sites. Regional transport of pollutants accompanied with different air mass origins arriving at the two sites and pollution sources in between the two cities caused larger seasonal variations in Zhuhai (> a factor of 3.5) than in Guangzhou ( 2.5 in Guangzhou and Zhuhai, respectively. Ship emissions, a source factor previously ignored in making emission control policies in the Pearl River Delta region of south China, were among the top contributors to PM 2.5 at both sites, accounting for > 17% of PM 2.5 mass concentrations.

A fraction of organic carbon (OC) is found to exhibit the capability to absorb solar radiation. However, the absorption properties of OC remain poorly characterized partly due to uncertainties in determination methods. In this study, the absorption coefficient (bap) of OC (bap,OC) in Beijing during a polluted winter was estimated on the basis of the combined measurements of black carbon (BC) size distribution and total aerosol bap (bap,meas). The bare BC bap (bap,bareBC) calculated using Mie theory on the basis of measured size distribution exhibited weak wavelength dependence, with a mean absorption Angstrom exponent (AAE) of 0.56 ± 0.04 within the 470–660 nm wavelength range, which was lower than the value of 1 commonly used for freshly emitted BC. The calculated bap,bareBC was compared with bap,meas at 950 nm to derive the coating thickness of BC, from which the calculation of coated BC bap (bap,coatBC) within 370–660 nm was based using the core–shell Mie model. Given the thick coatings, the AAE of coated BC, with a mean of 0.53 ± 0.12, was slightly lower than that of bare BC. Subsequently, bap,OC was obtained by subtracting bap,coatBC from bap,meas, accounting for 59.57 ± 4.82% of bap,meas at 370 nm on average. The average mass absorption efficiency of OC was estimated to be 1.48 ± 0.36 m2 g−1 at 370 nm. bap,OC significantly decreased as wavelength increased, deriving an AAE of OC with a mean of 2.72 ± 0.32 within the 370–660 nm range. The level of bap,OC estimated on the basis of a widely used attribution method assuming a constant BC AAE of 1 was ~60% lower than the currently presented value, probably underestimating OC radiative effect by a factor of >3. More accurate estimations of bap,OC based on more advanced measurements and suitable theory calculations are recommended to provide more reliable assessments of OC radiative effects.

The morphology of externally mixed black carbon (extBC) aerosols, an important factor affecting radiative forcing, was studied by a tandem method coupling a differential mobility diameter (DMA) with a single-particle soot photometer (SP2). Ambient particles were selected by the DMA, and the size-resolved extBC particles were distinguished from those of a thick coating (internally mixed) and quantified by the SP2. Time differences between the DMA size selection and the SP2 measurement were processed previously, as well as the effects of multicharged particles. Based on the mass-mobility relationship, the fractal dimension of the extBC particles was obtained, with a value of 2.36 ± 0.04. This value is comparable with those of diesel exhaust particles, implying a predominant contribution of vehicle emissions to the ambient extBC in urban Beijing. The effective densities (ρeff) of the extBC in the mobility diameter range of 140–750 nm were also derived, with values gradually decreasing from 0.34 g cm−3 at 140–160 nm to 0.12 g cm−3 at 700 nm. The ρeff values were generally lower than those measured using the DMA-aerosol particle mass analyzer (APM) system. This was most likely due to the lower BC masses determined by the SP2 compared to those from the APM, since the SP2 measured the mass of pure refractory BC instead of the entire BC aggregate consisting of both refractory BC and nonrefractory components measured by the APM.

The 12 May 2008 Wenchuan earthquake in China triggered many rock avalanches that disrupted the transportation system and thereby caused additional fatalities. In this paper, several lines of evidence were forwarded to show that the rock avalanches, distributed along some highly destructed areas, i.e., the main seismic fault (F 2 ), had been enhanced by natural explosions and fires immediately after the main earthquake. Burned rock samples from the explosion pits near the highly destructed parts of Shuijingyan (SJY), north of Beichuan County, were collected and analyzed in the laboratory. The brown porous ejecta were featured by intensive thermophili degradation because they had high content of polycyclic aromatic hydrocarbons. Microstructure and composition analyses indicated that four samples, a mixture of reef limestone and manganese ore, were carbonate manganese and carbonaceous rock, which generally is buried at 500–2000 m depth. With high content of polycyclic aromatic hydrocarbons, the brown porous ejecta were believed to have reached a highly thermal degradation process compared with surrounding and intact counterpart rocks.

We experimentally demonstrate a new method for modulating the light polarization state of the fiber. Both of the light polarization degree and polarization direction can be modulated. In the experiment, microfiber is immersed into the magnetic fluid (MF). When there is external magnetic field, magnetic nanoparticles of the MF generate magneto-optical dichroism and a non-circular symmetric distribution around microfiber. The light polarization state is modulated when the light passes the microfiber. When the external magnetic field rotates from 0o to 360o, the light polarization modulating exerts good polarization direction response.

Regional transport and chemical conversions are two major processes that lead to the severe haze pollution in China. Our observations during five haze episodes in Beijing between February 19 and March 12 of 2014 show that the two processes played different roles as PM

We propose a hollow core Bragg fiber (HC-BF) with a heterostructured cladding based on the ternary 1-D photonic crystal (T-1DPC) in this paper. The distinguishing ternary unit cell of T-1DPC is formed from a polyetherimide (PEI) layer sandwiched by two As2Se3 layers of the same thickness. We demonstrate its capability for mid-infrared broadband and low-loss transmission by numerically simulating and analyzing the omnidirectional photonic bandgap (OPBG) and the modal loss characteristics. The results show that the T-1DPC-based heterostructured cladding can effectively broaden the OPBG, which is only due to the blue-shift of the lower bandgap edge wavelength. Compared with that for the binary-1DPC-based HC-BF, the transmission loss for the T-1DPC-based HC-BF can be reduced by three orders of magnitude over most of the OPBG range. The large loss contrast is essentially attributed to the enhancement of the multilayer reflection from the T-1DPC-based cladding. Most notably, for a T-1DPC-based cladding with three groups, the transmission band with loss lower than 0.01 dB/m for the HE11 mode can cover almost the whole 3 to 5 μm range, with the exception of several loss peaks near the short-wavelength edge. Even with the cladding material absorption included, the transmission loss for the HE11 mode in the T-1DPC-based HC-BF can be still lower than 0.1 dB/m over the whole OPBG range.

Water solubilities of anthracene and phenanthrene were measured by adding a plant-derived biosurfactant Saponin and/or synthetic surfactants correspondingly below and above their critical micelle concentrations (CMCs). The results showed that the solubilities of anthracene and phenanthrene in water were greatly enhanced following a linear fashion if adding Saponin, TX100 and Brij35, respectively. The enhancing solubility capacities for Polycyclic aromatic hydrocarbons (PAHs) followed the order as: Saponin > Brij35 > TX100 at the concentrations below their CMC. It also proved that biosurfactant Saponin exhibited much higher enhancement efficiency for PAHs solubilization than the synthetic ones at the concentrations below the CMC. However, the solubility enhancement efficiencies of surfactants above the CMC turned to be the following order as Brij35 > Saponin > TX100. Furthermore, this study has confirmed that PAHs are synergistically solubilized in the mixed biologic-synthetic surfactant solutions, especia...

We consider bounded parallel-batch scheduling with proportional-linear deteriorating jobs and the objective to minimize the total completion time. We give some properties of optimal schedules for the problem and present for it a dynamic programming algorithm running in O(b2m22m) time, where b is the size of a batch and m is the number of distinct deterioration rates.

We propose a method of trapping micro-particles with microfiber enhanced by Sagnac interferometer. The microfiber waist diameter is 2.24µm. It is single mode fiber and has relatively large evanescent wave when it works in the water based suspension with wave length of 1550nm. The amplitude of the stationary wave formed in Sagnac interferometer is enhanced. The particles trapping ability with the crest of the stationary wave is increased either. This particles trapping experiment is carried out with light power of about milli-watt and 1µm polystyrene microsphere. Micro-particles could be trapped in a quasi-static state.

Daily PM

The response of microfiber polarization modulation (PM) to protein induced self-assembly of functionalized magnetic nanoparticles is tested. Microfiber is directly immersed in the magnetic fluid (MF) which contains carboxylated magnetic nanoparticles (CMNPs), without the modification of the microfiber surface. Self-assembly of CMNPs is induced after adding bovine serum albumin (BSA) into the MF. The relaxation time of the microfiber PM is prolonged, when an external magnetic field is applied or removed for a given period of time. The maximum polarization degree pmax and the difference Δp between the maximum and minimum polarization degree all decrease with the increase in the BSA concentration. The BSA concentration can be acquired based on the detection of pmax and Δp. Similarly, if specific molecular probes are prepared on the CMNPs to couple with the target proteins, new kinds of label free fiber biosensors can be expected. It can not only simplify the operation of microfiber but also reduce the cost of the signal analysis system.

We demonstrate an in-line fiber polarization modulator (FPM) which is constructed by immersing a microfiber into magnetic fluid (MF) and modulated with the magnetic field. The polarization modulation principle is based on the magneto-optical dichroism of the MF and the non-circular symmetric distribution of magnetic nanoparticles around the microfiber. Modulations of both the light polarization degree and the polarization direction are realized. The modulation capability, time response, insertion loss, and magnetic field direction dependence of the proposed FPM are studied.

In this work, a color ghost image of a black-and-white object is obtained by a real-time pseudocolor coding technique that includes equal spatial frequency pseudocolor coding and equal density pseudocolor coding. This method makes the black-and-white ghost image more conducive to observation. Furthermore, since the ghost imaging comes from the intensity cross-correlations of the two beams, ghost imaging with the real-time pseudocolor coding technique is better than classical optical imaging with the same technique in overcoming the effects of light interference.

Propagation characteristics of the femto-second chirped soliton pulse in dispersion-flatted fiber with linear dispersion profile (DFF-LDP) are numerically investigated by using the split-step Fourier method (SSFM), and variations of its characteristics affected by high-order dispersion (β2~β6), Raman effect, fiber loss and linear chirp parameter C are studied. A new type of DFF-LDP with negative dispersion slope is presented. The pulse broadens with the increase of propagation distance mainly because of fiber loss and third order dispersion (TOD). The effect of the positive chirp on pulse broadening is greater than that of the negative chirp. The time-delay induced by TOD and Raman effect appears, and decreases with increase of the chirp |C|. The main body of the pulse spectrum shifts to the long-wavelength region, an obvious separated spectrum appears in the short-wavelength region. The separated spectrum for the chirped case is more obvious than that for the unchirped case.

The supercontinuum (SC) spectrum generation is proposed in dispersion-flatted fibers with concave dispersion profile (DFF-CCDP). The effects of pulse characteristics and the fiber parameters on the SC spectrum characteristics are numerically investigated in the DFF-CCDP by using the split-step Fourier method. The characteristics of the SC spectrum become worse when the parameters are much smaller or greater. The parameters should be set according to the practical applications.