Small Extinction Coefficient Research Articles

Comparison of the polluted dust plume and natural dust air mass in a spring dust event in Beijing 2023

The occurrence of extreme weather events is becoming more frequent due to global climate change. A long-lasting dust outbreak in the spring of 2023 was triggered by Mongolia cyclones and cold fronts in the dust source areas. In this study, we illustrate the spatial distribution, the transport path of the dust and its influence on the air quality of downstream cities utilizing ground-based and space-borne measurements. Results indicate a more complicated pollution, coexisting of polluted dust stage S1 and pure dust stage S2. In S1, the aerosol was characterized by a dual-layer vertical structure—high extinction coefficient of nearly 1.0 km−1 with a low particle depolarized ratio (PDR) of < 0.1 under 500 m, and a small extinction coefficient of 0.3 km−1 with a high PDR of 0.15 above 500 m. Then the intrusion of the Mongolian cyclone carried new dust plumes on 10 March, suggesting the onset of pure dust period S2. The source transition was also confirmed by the MODIS, CALIPSO and Hysplit observations. The pure Asian dust evolved rapidly with one thickening layer and distributed homogeneously in the boundary layer. The PDR increased significantly to the peak of 0.35 and resulted in the peak PM10 value of > 1300 µg/m3. PM10 positively correlated with trace gases in S1 while varying inversely with the pollution gases in S2. The results help to shed light on the classification of different types of dust and also be useful in developing an effective strategy to forecast air pollution in downstream areas.

Synthesis, structural, optical, and thermal properties of LaFeO3/Poly(methyl methacrylate)/Poly(vinyl acetate) nanocomposites for radiation shielding

This work is an attempt to develop flexible radiation shielding based on a blend of polymethyl methacrylate (PMMA)/polyvinyl acetate (PVAc) and LaFeO3 nanoparticles (NPs). LaFeO3 and LaFeO3/PMMA/PVAc were made using simple chemical techniques. A high-resolution transmission electron microscope (HR-TEM) and X-ray diffraction (XRD) showed that well-crystallized LaFeO3 NPs with particles 79 nm in size and an orthorhombic shape were obtained. In addition, XRD confirmed the existence of PMMA, PVAc, and LaFeO3 in the nanocomposite films. Fourier transform infrared (FTIR) confirmed that the LaFeO3 NPs and the reactive functional groups in the blend interacted with each other. Field emission-scan electron microscope (FE-SEM) analysis showed that PMMA and PVAc form a homogenous blend and that the LaFeO3 NPs were spread out inside and on the blend surface. The samples showed transmittance in the range of 30–74% and a small extinction coefficient (≤ 0.08). The samples exhibited a dual-band gap structure, and the direct (indirect) band gap shrank from 5.1 to 4.7 eV (4.9 to 4.4 eV). The thermal analyses showed that the samples are thermally stable up to 260 °C. The Phy-X/PSD software was used to figure out the theoretical gamma-ray attenuation parameters, such as the mass attenuation coefficient, the mean free path, and the half-value layer, for different PMMA/PVAc + x% LaFeO3 composites. It is demonstrated that the PMMA/PVAc + 10 wt% LaFeO3 sample exhibits much better shielding effectiveness than PMMA/PVAc, and hence it is suitable for protecting against radiation.

Synthesis of ultra-small MXene nanorods for enhanced photothermal therapy of breast cancer in vitro

Photo-responsive nanomaterials show promising photothermal therapy (PTT) applications for superficial and internal tumors. However, most photo-synthesizers possess a small extinction coefficient and low photothermal conversion efficacy, limiting their use for advanced PTT. Herein, a facile and inexpensive method was employed to synthesize ultra-thin titanium carbide (Ti2C) MXene nanorods for the PTT of breast cancer. The average width and length of the prepared Ti2C nanorods were about 20 nm and 80 nm, respectively, demonstrating excellent biocompatibility and significantly encapsulated into the 4T1 cancer cells. The nanorods revealed promising photothermal properties and increased temperature from 20 to 58 °C enough for tumor ablation after 808 nm laser light irradiation, indicating remarkable cancer PTT in vitro. Moreover, Ti2C nanorods show favorable photostability and significant photothermal conversion efficiency of 63.3 % because of good near-infrared (NIR) absorption. This work proves ultra-thin Ti2C MXene nanorods as a new photothermal agent for phototherapy applications.

First-principles calculations to investigate the dielectric and optical anisotropy in two-dimensional monolayer calcium and magnesium difluorides in the vacuum ultraviolet

Anisotropic dielectric and optical properties of two-dimensional (2D) calcium and magnesium difluorides were investigated in the vacuum ultraviolet (VUV) region of the electromagnetic spectrum (EM) using the first principles density functional theory (DFT). The anisotropy between the in-plane and out-of-plane directions shows that these materials are uniaxial, exhibiting optical and dielectric anisotropy. The optical functions of these anisotropic materials-optical absorption, photoconductivity, refractive index, reflection and extinction coefficients, and electron energy loss (EEL) spectra-are calculated in the framework of DFT. The low refractive index values and relatively small extinction coefficient make these materials alternative low-index 2D materials for the long wavelengths in the VUV region of the EM spectrum. The reflection and transmission spectra indicate the antireflective property of these materials. The calculated EEL function shows less energy loss of fast-traveling electrons in the material's medium. The maxima in the EEL spectrum are the main feature of plasma oscillations. The dissipation in the incident light radiation energy propagating through the dielectric medium is estimated with the dielectric loss tangent (tanδ). The magnesium difluoride is identified as a less dielectric loss medium than calcium difluoride in the VUV region. The present results suggest that these 2D materials are promising in low refractive index, high reflective, and antireflective coating materials in optoelectronic device applications. Also, electronic studies revealed that these are excellent materials for gate insulators in field-effect transistors based on 2D electronic materials.

Bound states in the continuum (BIC) in silicon nanodisk array on mirror structure: Perfect absorption associated with quasi-BIC below the bandgap

A structure composed of a hexagonal array of Si nanodisks having toroidal dipole resonances and a reflecting mirror separated by a SiO2 spacer is proposed as a platform that exhibits narrow-band perfect absorption in the Si sub-bandgap wavelength range for a CMOS compatible Si based photodetector operating below the bandgap range. The numerical simulation reveals that the structure possesses Fabry–Pérot bound states in the continuum at proper spacer thicknesses due to the interference between the toroidal dipole and its image dipole. By slightly detuning the spacer thickness to meet the critical coupling condition, narrow-band perfect absorption appears despite assumption of a very small extinction coefficient (5 × 10−4). The wavelength of the perfect absorption is controlled in a wide range by the structural parameters of a Si nanodisk hexagonal array and is insensitive to the fluctuation of the extinction coefficient and the choice of a metallic mirror. In the structure, over 90% of incident power can be absorbed in the Si region. This suggests that the structure can be used as a narrow-band photodetector operating in the Si sub-bandgap wavelength range. We also evaluate the sensing performance of the proposed structure as an intensity based refractive index sensor operating in the near-infrared range.

Gallium Phosphide Nanoparticles for Low‐Loss Nanoantennas in Visible Range

AbstractColloidal nanoparticles of gallium phosphide (GaP) with moderately high refractive index (n &gt; 3) and a small extinction coefficient in the visible range are developed using a combination of mechanical milling and a pulsed laser melting process in solution. The combined process yields GaP nanoparticles with an almost spherical shape and the smooth surface. The single particle scattering spectroscopy reveals that smoothening of the surface by the pulsed laser melting process is crucial for achieving distinctive Mie resonances of the dipolar and higher‐order modes in the visible range. The near‐field profile at the Mie resonances studied by electron energy loss spectroscopy in a scanning transmission electron microscope confirms the existence of the magnetic dipole mode. Finally, the Purcell enhancement of fluorescence of molecules on the surface due to the Mie resonances is demonstrated.

Structural color printing via polymer-assisted photochemical deposition

Structural color printings have broad applications due to their advantages of long-term sustainability, eco-friendly manufacturing, and ultra-high resolution. However, most of them require costly and time-consuming fabrication processes from nanolithography to vacuum deposition and etching. Here, we demonstrate a new color printing technology based on polymer-assisted photochemical metal deposition (PPD), a room temperature, ambient, and additive manufacturing process without requiring heating, vacuum deposition or etching. The PPD-printed silver films comprise densely aggregated silver nanoparticles filled with a small amount (estimated <20% volume) of polymers, producing a smooth surface (roughness 2.5 nm) even better than vacuum-deposited silver films (roughness 2.8 nm) at ~4 nm thickness. Further, the printed composite films have a much larger effective refractive index n (~1.90) and a smaller extinction coefficient k (~0.92) than PVD ones in the visible wavelength range (400 to 800 nm), therefore modulating the surface reflection and the phase accumulation. The capability of PPD in printing both ultra-thin (~5 nm) composite films and highly reflective thicker film greatly benefit the design and construction of multilayered Fabry–Perot (FP) cavity structures to exhibit vivid and saturated colors. We demonstrated programmed printing of complex pictures of different color schemes at a high spatial resolution of ~6.5 μm by three-dimensionally modulating the top composite film geometries and dielectric spacer thicknesses (75 to 200 nm). Finally, PPD-based color picture printing is demonstrated on a wide range of substrates, including glass, PDMS, and plastic, proving its broad potential in future applications from security labeling to color displays.

Numerical Study of the Influence of Coupling Interface Emissivity on Aerogel Metal Thermal Protection Performance.

For aerogels in metal thermal protection system (MTPS), radiative heat transfer will participate in the thermal transport process. Therefore, the influence of the emissivity of the coupling interface between metal and aerogels on thermal insulation performance is considered an important research focus. In this paper, CFD numerical simulation is performed to study the influence of emissivity on the performance with different extinction coefficients at different boundary temperatures. The finite volume method and the discrete ordinate method are used to solve the govern equations. The results show that when the boundary temperatures are 600 K and 2100 K, the extinction coefficient is 50 m−1, and the reduction percentage of the effective thermal conductivity with an emissivity of 0.2 can be up to 47.5% and 69.8%, compared to the system with an emissivity of 1. Thus, the reduction in emissivity has a good effect on the thermal insulation performance of the MTPS at a higher boundary temperature for materials with small extinction coefficients.

Uranium(III)–Phosphorus(III) Synergistic Activation of White Phosphorus and Arsenic

Uranium(III)–Phosphorus(III) Synergistic Activation of White Phosphorus and Arsenic

Demonstration of Spin-Multiplexed and Direction-Multiplexed All-Dielectric Visible Metaholograms.

The optical holography technique realized by metasurfaces has emerged as a novel approach to projective volumetric display and information encryption display in the form of ultrathin and almost flat optical devices. Compared to the conventional holographic technique with spatial light modulators, the metahologram has numerous advantages such as miniaturization of optical setup, higher image resolution and larger field of visibility for holographic images. Here, a protocol is reported for the fabrication and optical characterization of optical metaholograms that are sensitive to the spin and direction of incident light. The metasurfaces are composed of hydrogenated amorphous silicon (a-Si:H), which has large refractive index and small extinction coefficient in the entire visible range resulting in high transmittance and diffraction efficiency. The device produces different holographic images when the spin or direction of incident light are switched. Therefore, they can encode multiple types of visual information simultaneously. The fabrication protocol consists of film deposition, electron beam writing and subsequent etching. The fabricated device can be characterized using a customized optical setup that consists of a laser, a linear polarizer, a quarter waveplate, a lens and a charge-coupled device (CCD).

Study on water absorption characteristics of cubic Y2O3 films

Abstract Based on the electron beam evaporation with oxygen plasma assistance, Y2O3 films were prepared at different deposition temperatures and oxygen flow rates. X-ray diffraction showed that all deposited Y2O3 films had cubic phase with (2 2 2) plane preferred orientation. Spectrometer test results showed that water absorption decreases in transmittance and reflectance around the wavelength of 2.9 μm. According to Lorentz dispersion theory, a multi-oscillator model was established to calculate optical constants and the inhomogeneity of Y2O3 films in the wavelength range from 2.5 to 4 μm. The results indicate an abnormal dispersion phenomenon is appearing in the 2.5–4 μm wavelength region. It was found that under the same oxygen flow rate, higher substrate temperature leads to a greater refractive index and smaller extinction coefficient. When the oxygen flow rate is increased at the same substrate temperature, the extinction coefficient remains almost unchanged, while the refractive index decreases. In addition, the refractive index and the inhomogeneity of the films increase almost linearly as the grain size increases.

Development of a coupled aerosol lidar data quality assurance and control scheme with Monte Carlo analysis and bilateral filtering

Mie-scatter lidar can capture the vertical distribution of aerosols, and a high degree of quantification of lidar data would be capable of coupling with a chemical transport model (CTM). Thus, we develop a data quality assurance and control scheme for aerosol lidar (TRANSFER) that mainly includes a Monte Carlo uncertainty analysis (MCA) and bilateral filtering (BF). The AErosol RObotic NETwork (AERONET) aerosol optical depth (AOD) is utilized as the ground truth to evaluate the validity of TRANSFER, and the result exhibits a sharp 41% (0.36) decrease in root mean square error (RMSE), elucidating an acceptable overall performance of TRANSFER. The maximum removal of uncertainties appears in MCA with an RMSE of 0.08 km−1, followed by denoising (DN) with 50% of MCA in RMSE. BF can smooth interior data without destroying the edge of the structure. The most noteworthy correction occurs in summer with an RMSE of 0.15 km−1 and Pearson correlation coefficient of 0.8, and the least correction occurs in winter with values of 0.07 km−1 and 0.93, respectively. Overestimations of raw data are mostly identified, and representative values occur with weak southerly winds, low visibility, high relative humidity (RH) and high concentrations of both ground fine particulate matter (PM2.5) and ozone. Apart from long-term variations, the intuitional variation in a typical overestimated pollution episode, especially represented by vertical profiles, shows a favorable performance of TRANSFER during stages of transport and local accumulation, as verified by backward trajectories. Few underestimation cases are mainly attributed to BF smoothing data with a sudden decrease. The main limitation of TRANSFER is the zigzag profiles found in a few cases with very small extinction coefficients. As a supplement to the research community of aerosol lidar and an exploration under complicated pollution in China, TRANSFER can aid in the preprocessing of lidar data-powered applications.

Simple method to extract extinction coefficients of films with the resolution of 10-5 using just transmission data and application to intermolecular charge-transfer absorption in an exciplex-forming organic film.

A simple method is presented to determine the thickness, refractive index and extinction coefficient of a film with the resolutions of ±1 nm, ±2 × 10-3, and 6 × 10-5, respectively. The method requires only ultraviolet-visible-near-infrared spectroscopy measurement of the transmittance of films with thicknesses of a few micrometers. A very small extinction coefficient of intermolecular charge transfer (CT) absorption of an exciplex-forming organic film is measured in the sub-bandgap wavelength region. This is to demonstrate that the CT absorption with extinction coefficient in the range of 10-3 to 10-5 can be measured indeed using the method, which is in the same resolution as photothermal deflection spectroscopy and Fourier transform photocurrent spectroscopy. The simplicity and feasibility of the proposed approach is expected to promote active study of intermolecular CT absorption in exciplex-forming films.

Analysis on the extinction properties of nanofluids for direct solar absorption

Abstract Compared with conventional surface-based solar collectors, direct solar thermal collectors based on nanofluids have an improved photothermal efficiency. Optical extinction characteristics of nanofluids have an important effect on the photothermal properties. The influence of distribution characteristics of extinction spectra on photothermal properties is investigated. Extinction spectra of Gaussian and uniform distributions are constructed based on the average extinction coefficient of plasmonic Ag nanofluid. Temperature rises in nanofluids with different extinction spectra are calculated. With the broadening of extinction peak, the solar absorption properties are enhanced, and the temperature rise is improved. The uniformly distributed extinction spectrum has strong solar absorption and increased temperature rise even at a small average extinction coefficient. The extinction coefficient is proportional to the concentration of nanofluids. Therefore, nanofluids of uniform distributed extinction spectra can have strong photothermal properties even at low concentration, which is conducive to the stability and reliability of nanofluid-based solar collectors.

The detection sensitivity of commonly used singlet oxygen probes in aqueous environments

The sensitivity for singlet oxygen (1O2) of two convenient 1O2 probes, 1,3-diphenylisobenzofuran (DPBF) and 9,10-Anthracenediyl-bis(methylene)dimalonic acid (ABDA), has been investigated in different aqueous environments. Both probes are commercially available at reasonable cost and can be used with standard UV–vis spectrometers. Although DPBF is not soluble in neat water and is not specific to the detection of 1O2, it has very high, essentially diffusion-limited, reactivity towards 1O2; it can trap up to 50% of all 1O2 created in alcohol/water or micellar solution, and even more when replacing H2O by D2O, which makes it highly useful when the process under investigation does not yield much 1O2. On the other hand, ABDA has a much lower reactivity, reacting with only 2% of the singlet oxygen generated in H2O, as well as a smaller extinction coefficient, resulting in a much smaller spectroscopic response, but is soluble in neat water and is specific for 1O2, allowing for discrimination from other reactive oxygen species. The results presented here not only allow a comparative assessment of the usefulness of the two 1O2 probes, but also provide a reference for an accurate absolute quantification of the amount of 1O2 generated in an experiment from the observed absorbance bleach.

Mid-to-far infrared tunable perfect absorption by a sub - λ/100 nanofilm in a fractal phasor resonant cavity.

Integrating an absorbing thin film into a resonant cavity is the most practical way to achieve perfect absorption of light at a selected wavelength in the mid-to-far infrared, as required to target blackbody radiation or molecular fingerprints. The cavity is designed to resonate and enable perfect absorption in the film at the chosen wavelength λ. However, in current state-of-the-art designs, a still large absorbing film thickness (∼λ/50) is needed and tuning the perfect absorption wavelength over a broad range requires changing the cavity materials. Here, we introduce a new resonant cavity concept to achieve perfect absorption of infrared light in much thinner and thus, really nanoscale films, with a broad wavelength tenability by using a single set of cavity materials. It requires a nanofilm with giant refractive index and small extinction coefficient (found in emerging semi-metals, semi-conductors and topological insulators) backed by a transparent spacer and a metal mirror. The nanofilm acts both as absorber and multiple reflector for the internal cavity waves, which after escaping follow a fractal phasor trajectory. This enables a totally destructive optical interference for a nanofilm thickness more than 2 orders of magnitude smaller than λ. With this remarkable effect, we demonstrate angle-insensitive perfect absorption in sub - λ/100 bismuth nanofilms, at a wavelength tunable from 3 to 20 μm.

The lake scheme of the Common Land Model and its performance evaluation

The Common Land Model (CoLM) has been updated to a new version, but the lake scheme in CoLM (CoLM-Lake) has never been evaluated. This paper introduces the structure and physical processes of CoLM-Lake, and evaluates its simulation performance through the observations from 10 lakes over different regions. It also discusses the sensitivities of simulated results to some important parameters in the model. Results show that CoLM-Lake performs very well over the three shallow lakes (Kossenblatter, Taihu and Sparkling Lake) where the model accurately captures the magnitudes and seasonal variations of lake surface temperature, turbulent fluxes, and vertical thermal structure. The freeze-thaw cycle of Sparkling Lake is reproduced at a reasonable level as well. Also, CoLM-Lake show acceptable performance in simulating vertical structures and their variations for deep lakes, although the vertical mixing strength remains underestimated. The biases of surface temperatures in the Great Lakes of North America are relatively larger, but the magnitudes and seasonal variations in temperature fall within a reasonable range. In general, CoLM-Lake is suitable for the simulation of lake physical processes on the global scale. The simulated results have strong sensitivities to some parameters with values that have large uncertainties. The surface roughness lengths determine the amounts of turbulent fluxes which are emitted into the atmosphere, and thus affecting the simulated lake surface temperature. Although the surface roughness based on the dynamic diagnosis of lake properties in the model has made the simulated turbulent fluxes very accurate, the further adjustment of surface roughness can improve the realism of the simulated turbulent fluxes and temperature on lake surface. Lake depth, optical extinction coefficient and thermal diffusivity affect the simulated lake thermal structure from different angles. Lake depth determines the amount of water in vertical mixing; optical extinction coefficient determines the distribution of solar radiation at different lake depths; and thermal diffusivity determines the simulated vertical mixing strength that a lake can achieve. Either a larger lake depth, a smaller extinction coefficient, or a larger thermal diffusivity enables a lake to transfer and store more heat internally, thereby increasing lake thermal inertia, reducing daily and seasonal variations of lake water temperatures, and causing late freeze-up dates in winter. Therefore, the biases of simulated lake thermal structure can be corrected by adjusting the above three parameters. Note that lake depth and optical extinction coefficient are lake inherent attributes, and thus it is important to collect high-resolution and high-precision data for these two parameters in the future. The modification of thermal diffusivity should focus on increasing simulated vertical mixing strength for deep lakes, while the relatively accurate simulation for shallow lakes should be maintained, and thus more complex processes in deep lakes need to be considered in the model than simply multiplying the background thermal diffusivity of entire lake. The temperature at which lake water reaches maximum density is affected by lake salinity, and adjusting this temperature also improves simulated results. Hence, the effects of lake salinity on lake water physical properties should be considered in the development of future lake schemes. As three-dimensional lake schemes become more sophisticated, it is increasingly important to couple them into regional and global climate models. However, the description of important processes such as lake vertical mixing, phase change and snow hydrology are still too simple in one-dimensional schemes, and thus the upper limit of accuracy that one-dimensional schemes can achieve in deep lake simulations remains unclear, and the necessity of coupling the three-dimensional schemes with climate models is under dispute. If one-dimensional schemes are found to have better performance in simulating the characteristics of deep lakes, then the large amount of computational resources that need to be consumed to run three-dimensional models can be saved. Therefore, developing one-dimensional lake schemes at current stage is extremely important.

Cirrus Cloud Properties as Seen by the CALIPSO Satellite and ECHAM-HAM Global Climate Model

Cirrus clouds impact the planetary energy balance and upper-tropospheric water vapor transport and are therefore relevant for climate. In this study cirrus clouds at temperatures colder than −40°C simulated by the ECHAM–Hamburg Aerosol Module (ECHAM-HAM) general circulation model are compared to Cloud–Aerosol Lidar and Infrared Pathfinder Satellite Observations ( CALIPSO) satellite data. The model captures the general cloud cover pattern and reproduces the observed median ice water content within a factor of 2, while extinction is overestimated by about a factor of 3 as revealed by temperature-dependent frequency histograms. Two distinct types of cirrus clouds are found: in situ–formed cirrus dominating at temperatures colder than −55°C and liquid-origin cirrus dominating at temperatures warmer than −55°C. The latter cirrus form in anvils of deep convective clouds or by glaciation of mixed-phase clouds, leading to high ice crystal number concentrations. They are associated with extinction coefficients and ice water content of up to 1 km−1 and 0.1 g m−3, respectively, while the in situ–formed cirrus are associated with smaller extinction coefficients and ice water content. In situ–formed cirrus are nucleated either heterogeneously or homogeneously. The simulated homogeneous ice crystals are similar to liquid-origin cirrus, which are associated with high ice crystal number concentrations. On the contrary, heterogeneously nucleated ice crystals appear in smaller number concentrations. However, ice crystal aggregation and depositional growth smooth the differences between several formation mechanisms, making the attribution to a specific ice nucleation mechanism challenging.

Structure-Property Relationship Study of Donor and Acceptor 2,6-Disubstituted BODIPY Derivatives for High Performance Dye-Sensitized Solar Cells.

Seven donor and acceptor 2,6-disubstituted 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY) dyes have been synthesized and characterized. Including MPBTCA, which is a known compound, the seven BODIPY dyes have been characterized by varied physical methods, such as UV/Visible absorption spectroscopy, low energy photo-electron spectroscopy (AC-2), and HOMO-LUMO DFT/TDDFT calculation. All seven BODIPY dyes have absorption λmax around 535-545 nm, which is significantly longer than 499 nm of 4,4-difluoro-1,3,5,7,8-pentamethyl-4-bora-3a,4a-diaza-s-indacene (PM 546). Having structural variation on donor group, acceptor group, donor π-spacer, acceptor π-spacer, and the substituent on boron, some BODIPY dyes exhibit small extinction coefficients or spectral integrals in solution (MPCtBTCA, MPBT-pyO, MPBTT-pyO, MTBTCA), broadening absorption spectral profile (MTBTCA), weak intramolecular charge transfer characteristics (MPBT-pyO, MPBTT-pyO, MTBTCA), too low LUMO energy level (PPBTCA), or insufficient dye-uptake by TiO2 FTO (MPBT-pyO, MPBTT-pyO, MTBTCA). Two of the seven BODIPY dyes, MPBTCA and MPBTTCA, do not show the adverse properties like other BODIPY dyes. With our improved TiO2 FTO (fluorine doped tin oxide) dyeing method, namely a solution dropping method, high performance dye-sensitized solar cells (DSCs) have been realized by MPBTCA and MPBTTCA photosensitizers. Power conversion efficiencies of 6.3 and 6.4 % have been achieved by MPBTCA and MPBTTCA DSCs, respectively. To the best of our knowledge, MPBTCA and MPBTTCA are the most efficient dyes for the donor and acceptor 2,6-disubstituted BODIPY DSCs so far.

Evacuation speed in full-scale darkened tunnel filled with smoke

Tunnel fires create dense black smoke that covers ceiling lights and darkens tunnel spaces. The present study investigates experimentally the evacuation speed in a full-scale tunnel filled with smoke and clarifies the relation between the extinction coefficient (up to 1.6m−1) and normal walking speed. In this study, participants were exposed to smoke in a full-scale experimental tunnel that was darkened by turning off the ceiling lights, and the extinction coefficient was varied from 0.18 to 1.6m−1. The maximum, minimum, and mean normal walking speeds were almost constant up to 1.0m−1 but decreased slightly at higher extinction coefficients. At 0.30m−1, the maximum emergency-evacuation speed through the dark tunnel is less than that when the ceiling lights are on and corresponds to 2.6m/s, thereby indicating a fast walking speed even at small extinction coefficients. However, the maximum emergency-evacuation speeds at coefficients exceeding 0.48m−1 for light and dark conditions are almost identical. The minimum and mean emergency-evacuation speeds decrease at extinction coefficients of approximately 1.0m−1. Additionally, normal walking speed and emergency-evacuation curves are calculated from the current experimental results to compare the effect of ceiling lights with that of a darkened space. The results indicate that the normal walking speed and emergency-evacuation speed are influenced by the darkened space.