Search

A photochrmic triangle terthiophene dye with 2,4-dimethylthiazole attached was synthesized and shows regular photochromic properties when irradiated with UV/Vis light alternately. It was found that the attaching of 2,4-dimethylthiazole has a significant effect on both the photochromism and fluorescence of triangle terthiophene. During the photocyclizatioin prcess, not only the color but also the fluorescence of the dye in THF can be toggled between ring-open and ring-closed forms of the dye. Additionally, the absolute quantum yields (AQY) of ring-open and ring-closed forms of the dye (0.32/0.58) were greatly larger than the literature report. Along with the 254 nm light irradiation, the fluorescence color changed from deep blue (428 nm) to sky blue (486 nm) in THF. A fluorochromism cycle could be established based on the UV/visible light irradiation cycle, which provides a strategy for the design of new type fluorescent diarylethene derivatives for biological application. [ABSTRACT FROM AUTHOR]

An energy cassette, N-butyl-6-(3-phenylethynyl-1,3,7,9-tetramethylBODIPY)-naphthalimide (BON), was constructed with an energy donor and acceptor incorporated in a single molecular system. The energy donor (naphthalimide, NA) and acceptor (BODIPY) were bonded through phenylacetylene, a conjugate linker. Highly twisted molecular conformation was formed due to intramolecular repulsion, forcing the two fluorophores to act as independent chromophores. Therefore, the absorption spectra of BON in a common organic solvent are of superimposition of NA and BODIPY. Upon excitation of UV light (365 nm), a typical BODIPY emission character was observed, indicating an efficient energy transfer from NA moiety to the BODIPY scaffold with a transfer efficiency of 98%. Additionally, the pseudo-Stokes' shift expanded to around 140 nm, which is largely longer than traditional BODIPY dyes (~ 10 nm). The frontier molecular orbitals analysis shows that there exists a pronounced electron density shifting from HOMO to LUMO, suggesting the efficient energy transfer in BON. A through-space energy transfer cassette was established with the twisted molecular conformation-induced orbital decoupling and favorable mutual orientation of the excited NA/BODIPY moment vector. A dye pair (BON) was configured by naphthalimide and BOIDPY with a conjugate linker, phenylacetylene. Due to intramolecular repulsion in BON, the dye molecule is highly twisted, forming an efficient energy transfer cassette. An efficient energy transfer from NA to BODIPY occurred with a transfer efficiency of 98%. [ABSTRACT FROM AUTHOR]

A fluorescent turn-on sensor (BOPA) was configured by anchoring bis(pyridin-2-ylmethyl)-amine (DPA) unit to the BODIPY scaffold. It exhibits highly sensitivity and selectivity towards Pb2+, Ba2+, Cr3+, Cd2+, Hg2+, Zn2+ against the competent metal ions. Job's plot analysis supports the 1:1 stoichiometry of BOPA and metal ions. And linear relationship between fluorescence intensity and concentration of Zn2+ (representative metal ion) was observed over the range 0 ~ 20 μM Zn2+. The limit detection of BOPA in recognition of Pb2+, Ba2+, Cr3+, Cd2+, Hg2+, Zn2+ was ranged from 15.99 to 43.57 nM. Photo induced transfer (PET) in the excited state of BOPA determines the emission "off/on". Coordination of metal ions by DPA significantly weakened the electron-donating ability of nitrogen atom and inhibits the PET, recovering emission of BODIPY. In addition, the attachment of anisole at meso-position of BODIPY finely modulated the recognition of metal ions category. [ABSTRACT FROM AUTHOR]

Droplet charging is an effective method to enhance dust removal efficiency using an electrostatic spray scrubber (ESS). However, effects of the materials and dimensions of different electrodes on droplet charging efficiency have not been studied systematically. In this study, ring-shaped electrodes were selected to test effects of three types of electrode materials (copper, stainless steel, and graphite) with various dimensions on droplet charging efficiency. A Faraday pail charge measurement device was used to measure the droplet charge generated by the electrodes. A reduced factorial design with four factors was used in this study to investigate the charging efficiency affected by the factors. The four factors tested were electrode material, electrode diameter, nozzle height, and applied voltage. A 304L stainless steel electrode was found to achieve higher droplet charge-to-mass ratio (CMR) values than identically shaped electrodes made from either copper or graphite. The optimal stainless steel electrode inner diameter was 100 mm. The 304L stainless-steel electrode with this optimal diameter and a height of 45 mm achieved the highest mean CMR of 0.435 ± 0.002 mC kg−1 at an applied voltage of −11 kV with the bottom of the nozzle tip positioned 15 mm below the top of the electrode. Implications Currently, the low removal efficiency of submicron particles cannot meet the environmental control requirements of industrial applications that may have significant concentrations of particulate matter (PM) in this size range. As stricter environmental regulations are increasingly enforced, there is an urgent need to efficiently remove submicron dust particles from the air. Experiments show that the dust capture process is improved by charging droplets in the spray separator and reducing the secondary escape of dust particles in the electrostatic precipitator Although high-voltage charging of droplets has been investigated in many studies, the effect of electrode material and size on droplet CMR is still not fully understood. The purpose of this study was to (1) quantify the performance of 304L stainless steel (304L SS), copper, and high-purity graphite electrodes for spray droplet CMR, (2) evaluate effects of the applied voltage, nozzle height, electrode material and dimension on CMR, and (3) optimize the specific values of key design factors and operating parameters that lead to the highest CMR. The results of this study aim to optimize electrostatic spray scrubbers to achieve high droplet CMR values. [ABSTRACT FROM AUTHOR]

The relatively low-pressure layered hexagonal Li3B2 (h-Li3B2) phase under 20 GPa was identified on the basis of ab initio calculations. Inspired by the high-temperature superconductivity of metallic hydrogen, this study obtained a novel hexagonal Li2B2H (h-Li2B2H) structure by replacing Li2 with H. Contrast to h-Li3B2, h-Li2B2H may be directly synthesized by α-LiB and H2 under pressure. The two phases exhibited electronic features similar to those in MgB2 and were expected to be good superconductors. Electron–phonon coupling calculations illustrated that the layered h-Li3B2 structure is superconducting at 2 K with λ = 0.39 under 20 GPa. Moreover, h-Li2B2H was predicted to possess a large electron–phonon coupling parameter λ of approximately 0.81 and a resulting superconducting critical temperature about 28 K at 20 GPa. The introduced H in the h-Li2B2H structure had strong vibrational energy due to its light atomic mass and could enhance the energy of σ and π bonds by bonding with Li. Thus, the introduced H in the h-Li2B2H structure is important due to its enhanced electron–phonon coupling and superconducting property. [ABSTRACT FROM AUTHOR]

Optimization-based weight learning approaches that incorporate multiple sensor signals or vibration spectral components have demonstrated their effectiveness in monitoring mechanical systems. However, the current weight learning methods are limited by their reliance on linear fusion functions. The exploration of nonlinear link functions, particularly in the context of fusing spectral components in vibration spectra for health indices (HIs) construction, remains largely unexplored. Additionally, the development of formulas for interpreting HIs constructed using nonlinear fusion functions poses significant theoretical challenges. To address these limitations, this study proposes a novel nonlinear optimization-based weight learning model for constructing an HI that captures the nonlinear relationships among spectral components. This HI is designed to pinpoint fault characteristic frequencies while also highlighting other spectral lines associated with bearing degradation modelling. Furthermore, we derive formulas that enable the calculation of the contributions of frequency components to nonlinearly constructed HIs, thereby enhancing the interpretability of the model. By selecting an appropriate kernel function, subtle changes resulting from incipient faults and the underlying degradation process can be effectively captured. The effectiveness of the proposed model in detecting incipient faults, modelling degradation, and identifying fault types is validated through two run-to-failure case studies and a gearbox bearing experiment. [ABSTRACT FROM AUTHOR]

Machinery prognostics and health management (PHM) plays a key role in the reliable and efficient operation of industrial processes. With the emerging big data era, data-driven prognostic methods which avoid considering complicated system models have attracted growing research interest. Among many data-driven models, similarity-based prediction methods have been popular due to their strong interpretability and relatively simple implementation process. Nevertheless, when quantifying the similarity between two trajectories, most existing similarity measures neglect the nonlinearity of the distance measurement at different degradation stages and degradation alignments with timing difference, which may not be sufficient to retrieve the most suitable trajectories for remaining useful life (RUL) prediction. To overcome these limitations, a spherical-Dynamic Time Warping (spherical-DTW) algorithm is put forward to find an optimal match between the test and training trajectories at the retrieval step. Dynamic Time Warping allows degradation alignments with timing difference through stretching or compressing the trajectories with regard to time, thereby the data in similar degradation levels can be well aligned across different units. Moreover, a newly defined nonlinear spherical distance method is introduced and incorporated into the retrieval process to account for the nonlinearity of the damage propagation process. The significance of this study is that the newly proposed spherical-DTW algorithm goes one step further to consider the nonlinearity of fault evolutions and allow degradation pattern alignments with timing difference when performing similarity-based prognostics. Two run-to-failure cases, involving a real-world industrial compressor failure case and a gas turbine engine failure dataset, are investigated to demonstrate the effectiveness and superiority of the proposed algorithm. [ABSTRACT FROM AUTHOR]

Drivers of coal mine excavators often encounter high-concentration dust attacks. To address this issue, this study aimed to develop a micro-clean space system as a personal protection method based on air curtain dust-isolating technology and a fresh air jet. We examined the barrier effect of air curtains for lateral airflow using airflow tracing and an airspeed measurement system. Dust tracing assessed the dust control performance of the micro-clean space system. A dust control efficiency experiment was conducted to quantify the influence of the discharge speed of the air curtain, speed of the fresh air jet, and air curtain cleanliness on the dust-proof performance of the proposed system. The results showed that the barrier effect of the air curtain for the lateral airflow was related to the discharge speed of the air curtain, air curtain supply angle, and the distance from the test point to the discharge nozzle, the air curtain jet speed of 20 m/s to the direction of the oncoming airflow deflection 30° can effectively enhance the barrier effect of the air curtain; The micro-clean space system effectively isolated the drivers from the high-concentration dust environment. The discharge speed of the air curtain was controlled at 9 m/s to achieve a stable, high-efficiency barrier against dust, whereas the speed of the fresh air jet was controlled at 5–11.8 m/s. The aforementioned parameter combination helped achieve a dust concentration of 5 mg/m3 and below in the space under monitoring, and the dust control efficiency was well over 90%. [Display omitted] • Air curtain system for protecting the mining excavator drivers. • A micro-clean space test system has been established. • Performance testing of dust control in micro-clean space. • The influence factors of the dust control performance. [ABSTRACT FROM AUTHOR]

In mines, the exhaust gas is mainly discharged from main ventilators in free dissipation state. The effective recovery of its kinetic energy is lucrative from economical and technical standpoints. This study is focused on recovering the kinetic energy of the exhaust gas without deteriorating the main ventilator's safe operation or increasing power dissipation. The related experiments and numerical simulations were performed for the conical diffusers with diffusing angles of 16° and inlet diameters of 220 and 320 mm, respectively. By examining the start-up and operation states of the wind turbines using inlet collectors with conical, circular arc, and cone-arc shapes, it was found that the wind speed at the inlet of the drainage tube exceeded 4 and 20 m/s at the minimal and maximal distances from the wind turbine, respectively. The wind speed at the overflow tube outlet was no less than 1.8 m/s, proving a certain recovery of kinetic energy by the wind turbine. Thus, the critical distance between the diffuser and the inlet collector should be at least four times the diffuser's inlet diameter. Finally, the velocity, pressure, and flow fields in the vortex core regions of the kinetic recovery system with different types of inlet collectors were simulated with the FLUENT commercial software package. The simulation results revealed that the circular-arc collector outperformed other three tested configurations in kinetic energy recovery. Implications: This study is focused on recovering the kinetic energy of the exhaust gas without deteriorating the main ventilator's safe operation or increasing power dissipation. China is a country with coal as its main energy source, which releases over ten billion cubic meters of the exhaust gas annually. In addition to low-concentration methane, there is also the exhaust gas released at a velocity of about 20 m/s, which kinetic energy recovery would be very lucrative. The significance of this study is that the mine's main ventilator outlet was simplified as two conical diffusers with parameters α=16°/n=2 and α=16°/n=2.5, and the optimal critical distance between the diffuser and the collector was determined as 4Di, where Di was the diffuser's inlet diameter. Under that optimal condition, the system can achieve the maximum power without affecting the ventilator's normal operation. It is instructive to make full use of and manage the exhaust gas in mine that fits the journal on the purpose of air waste management. Finally, we provide a statement serious that the article is original and unpublished and is not being considered for publication elsewhere. [ABSTRACT FROM AUTHOR]

Dipyrrolydiketones BF2 complex was synthesized and characterized by NMR, HRMS, and single crystal diffraction. In non-polar environment, this BF2 containing dye emitted bright blue-green fluorescence. No significant spectra shift was observed both in absorption and emission spectra, which indicates the insensitivity of absorption/emission toward environment. The alkyl substituted pyrrole rings lead to its highly emission character in solid state by enhancing the distance between dye molecules. Absolute quantum yields were determined to be 0.51–0.78/0.36 in selected organic medium and solid state, respectively. The emission dynamics was investigated by fluorescence lifetime and both monoexponential and bi-exponential decay was observed. [ABSTRACT FROM AUTHOR]

[Display omitted] The air curtain system can collect the dust particles from hard-to-seal sources, which proves to be a feasible method for satisfying the increasing dust prevention requirements in China. In this study, aiming at addressing the dust escape problem at the tobacco stem loading point in a tobacco factory, a rotational flow air curtain dust-collecting system with a size of 2m x 2m x 2m was used for dust collection. The dust-collecting characteristics using the original dust suction hood and the developed air curtain dust-collecting system were analyzed and compared. Results show that the external dust concentration when the original dust suction hood operated was as high as 83.65 mg/m3, with a dust-collecting efficiency of only 16.35 %, suggesting serious dust escape; after the use of the developed air curtain dust-collecting system, the dust-collecting efficiency reached up to 86.93∼94.76 % under the same operating conditions. By studying the influence of two factors, air curtain jet velocity and exhaust-to-pressure ratio, on the dust collection efficiency of the air curtain system, at an exhaust-to-pressure ratio of 0.8 and an air curtain jet velocity of 13.5 m/s, the corresponding dust-collecting efficiency reached a maximum of 94.76 %. The present test results confirmed a better application effect of the developed air curtain dust-collecting system than the original dust-collecting system at the industrial loading point. Using the developed air curtain dust-collecting system is mainly aimed at the dust source, reduce the dust in the workshop dissemination and dispersion that can lower the transmission path of COVID-19 via aerosol. [ABSTRACT FROM AUTHOR]

In this study, a three‐step remaining service life (RSL) prediction method, which involves feature extraction, feature selection, and fusion and prognostics, is proposed for large‐scale rotating machinery in the presence of scarce failure data. In the feature extraction step, eight time‐domain degradation features are extracted from the faulty variables. A fitness function as a weighted linear combination of the monotonicity, robustness, correlation, and trendability metrics is defined and used to evaluate the suitability of the features for RSL prediction. The selected features are merged using a canonical variate residuals‐based method. In the prognostic step, gray model is used in combination with empirical Bayesian algorithm for RSL prediction in the presence of scarce failure data. The proposed approach is validated on failure data collected from an operational industrial centrifugal pump and a compressor. [ABSTRACT FROM AUTHOR]

A fluorescent turn-on chemosensor (BA) was constructed by attaching bis(pyridin-2-ylmethyl)-amine (DPA) unit to the BODIPY scaffold. It can give a prominent green/yellow fluorescent response selectivity with each of Zn2+/Hg2+/Cd2+/Ca2+/Mn2+/Pb2+/Al3+. The 1:1 stoichiometry of BA and metal ions was drawn from the analysis of Job’s plot. The limit detection of BA in recognition of Zn2+/Hg2+/Cd2+/Ca2+/Mn2+/Pb2+/Al3+ is ranged in 50.8-146.6 nM. There exists a linear relationship between the fluorescence intensity and concentration of metal ions (Zn2+: 4-15 µM). The mechanism of fluorescence signal “turn-on” is based on the photo induced transfer (PET) in the excited state of BA. The coordinated metal ions significantly weakened the electron-donating ability nitrogen atom in DPA, thus recovering the emission character of BODIPY. The substituted group at the phenyl ring in meso-position of BODIPY scaffold determines the recognizable list of metal ions. [ABSTRACT FROM AUTHOR]

[Display omitted] • Chemosensor was configured by attaching responsive group, diaminomaleonitrile, to BODIPY scaffold. • Cu2+ can be selectively recognized on a 2-s time-scale. • The recognition mechanism is based on the Cu2+ induced intramolecular oxidative cyclization of γ-aminoimine. • The absolute fluorescence quantum yield of BD + Cu2+ is determined to be 98%, attributing to the formation of dicarbonitrile substituted imidazole ring. A highly fluorescent Cu2+-responsive sensor, 2-amino-3-(BODIPYmethyleneamino)maleonitrile (BD) was constructed by attaching diaminomaleonitrile to a BODIPY scaffold. Cu2+ can be selectively recognized on a 2-s time-scale by way of fluorescence emission. When Cu2+ and BD coexist in solution, typical BODIPY emission was observed and the emission intensity could be increased to 334 times that of the blank dye solution. The mechanism of fluorescence increase is based on the generation of highly fluorescent species by Cu2+-triggered oxidative cyclization of the attached diaminomaleonitrile. The absolute fluorescence quantum yield (AFQY) of the cyclization product is 98% determined by integrating sphere. The highly emissive character can be attributed to the imidazole ring and dicarbonitrile on the BODIPY scaffold. It surpasses the meso -phenyl substituted analogue in AFQY and detection limits (DL). The specific Cu2+ recognition behavior was also validated in Hela cells with high-contrast fluorescence images. [ABSTRACT FROM AUTHOR]

In order to reveal multiscale dynamic distribution characteristics of dust collectors in a wet scrubber, a method for scale decomposition of dust collectors based on Wigner–Ville distribution (WVD), empirical mode decomposition (EMD) and Hurst analysis of grayscale signals is reported. The WVD features of grayscale signals were used to observe the energy distribution details of dust collectors at different frequency bands and time periods. Then, the scale decomposition of dust collectors based on EMD and Hurst analysis of the grayscale signals was carried out. These analysis results showed that the motion behaviors of micro-, meso- and macro-scale subsets of dust collectors were determined: specifically, the single fractal features of micro-scale subsets conform to the motion characteristics of individual dust collectors. The dual fractal characteristics of meso-scale subsets denote the interactions among dust collector aggregations. Additionally, the fractal features of the macro-scale subsets reflect persistent liquid surface fluctuation behavior in wet scrubbers. Finally, the relative contribution of dust collectors at different scales to the effectiveness of dust removal was represented. This is not only an important innovation in the study of micro mechanism of wet dust removal but provides powerful theoretical support for technological innovations in wet scrubbers. Implications: The multiscale dynamic distribution characteristics of dust collectors in wet dust scrubber were explored, using a method for scale decomposition of dust collectors based on Wigner–Ville distribution, empirical mode decomposition and Hurst analysis of grayscale signals. The fractal characteristics of different scales of dust collectors are determined. Besides, the contribution of different scales of dust collectors to the effect of dust removal is quantized. Therefore, this research is very meaningful, which not only has important innovation in the study of micro mechanism of wet dust collectors but provides a powerful theoretical support for technological innovation of wet dust scrubbers. [ABSTRACT FROM AUTHOR]

Photochromic core structure of BTEs was configured in the design of BT (2,3-Bis(2,5-dimethylthiophen)−5-phenylethynylthiophene) and NT (2,3-Bis(2,5-dimethylthiophen)−5-(4-methoxyphenyl)−1,3-butadiene-1,1,4,4-tetracarbonitrile). BT exhibits regular photochromic behavior in hexane when excited with UV (254 nm) and visible light (>400 nm). The solution can be cycled between pink colors and colorless. Correspondingly, NT, with a more electron-withdrawing group attached, the photochromic reactivity was totally quenched. It is the lowered electron density on reactive carbon atoms in LUMO that influence the photochromism, which is one of the key elements to photochromism. Apart from the distance between reactive atoms, electron distribution on reactive atoms is another important key to the configuration of photochromic dyes. [ABSTRACT FROM AUTHOR]

A heavy metals sensor (2-N,N-bis(pyridin-2-ylmethyl)methanamine-BODIPY, DB) for the recognition of Pb2+, Ba2+, Cr2+, Cd2+, Hg2+, Sn2+, and Zn2+ was developed by anchoring (bis(pyridin-2-ylmethyl)amine) DPA unit to the BODIPY framework. It exhibited excellent sensitivity and selectivity against other competent metal ions. The stoichiometry of DB and metal ions were determined to be 1:1. The limit of detection of DB toward Pb2+, Ba2+, Cr2+, Cd2+, Hg2+, Sn2+, and Zn2+ was ranged from 60.07 to 89.37 nM. Photo induced transfer (PET) leads to the weak emission of BODIPY unit. When metal ions anchored with DPA, PET was blocked due to the weak electron donating ability of N in DPA to BODIPY and the highly emissive character of BODIPY was recovered, establishing a fluorescence switch. [ABSTRACT FROM AUTHOR]

Single-image super-resolution (SISR) has been an important topic due to the demand for high-quality virtual images in the field of visual artificial intelligence. Methods based on deep learning have achieved great success based on the excellent capability of grasping complicated features of deep convolutional networks. The performance can be improved slightly but not obviously by simply widening or deepening the network. In this paper, we propose a merged convolutional network for super-resolution, which extracts more adequate details to restore high-resolution images. We used dense blocks for feature extraction to concatenate deep features with shallow features in depth. We also designed two sub-nets with distinct convolution kernels as different branches of the network, which can widen the network and improve the performance of the system. Finally, we employed sub-pixel layers to avoid feature distortion for up-sampling at the very end. Our method was evaluated using several standard benchmark datasets. The results demonstrate superior performance and good robustness compared with state-of-the-art methods. [ABSTRACT FROM AUTHOR]

A fluorine-boron (F-B) containing dye was configured and routinely characterized by nuclear magnetic resonance (NMR) and mass spectrometry (MS) technology. The absorption and emission behavior were investigated in selected solvent with different polarity. Both in chloroform and in solid powder state, it is highly emissive. The absolute fluorescence quantum yield was determined to be 0.60. The coordination lock of B atom prevents the free rotation of two fragment of the dye and limited the nonradiation transition, thus leading to the fluorescence emission character. In addition, significant Stoke's shift (∼190 nm) was observed. Similar emission maximum in solution and solid shows that the emission behavior is insensitive to molecular aggregation behavior. In all the case, the emission colors were demonstrated by Commission internationale de l'éclairage (CIE) chromaticity system. [ABSTRACT FROM AUTHOR]

Diethylaminocoumarin with imidazole as the bridge unit and phenyl rings appended was synthesized by conventional condensing method and routinely characterized by nuclear magnetic resonance and high resolution mass spectra technology. The absorption and emission behavior were studied in various polar environment. It exhibit highly emissive character in methanol with 89% emission quantum yield. In solid state, the fluorescence color shifts to yellow part with emission peak around 563 nm. Emission decay in solid state demonstrates the single index character of the excited dye molecules. Together with the conformation derived from single crystal structure, balanced driving force between regular and irregular packing trend leads to the highly emissive character. [ABSTRACT FROM AUTHOR]

On account of certain technological requirements, it is difficult for some industrial processes that generate dust to be sealed in a fixed pattern and ventilated for dust discharge, mainly automatic welding, pressure casting, wood processing, and crop production, which has become a significant bottleneck in dust control. The present study developed a transverse-flow soft-sealing dust control system, in which four novel air curtain generators were arranged in a square pattern within the region where dust was generated to create end-to-end planar transverse-flow air curtains and achieve soft sealing. The air suction inlet was placed centrally above the area where dust was generated; under the suction airflow, the dusty air was gradually diluted and driven away to effectively suppress dust escape. The flow field characteristics in the area where dust was generated and the performance of the developed sealing system in controlling fine smoke dust were qualitatively analyzed using a tracing experiment with smoke dust. Tracing experimental results on leaf powder qualitatively reveal directional dust control of large dust particles. Moreover, the dust control efficiency was evaluated under different conditions to quantitatively investigate the effects of air curtain outlet velocity, exhaust-to-pressure ratio, and jet angle. The results show that with a greater air supply and air suction rate, the airflow exhibited a more obvious entrainment effect and stronger dust exhaust and discharge, and simultaneously, the formed tracing smoke column had a clearer boundary. At an air curtain outlet velocity of 6.27–8.39 m/s and a corresponding air supply rate of 17.00–22.57 m3/min, a stable air curtain was formed, which achieved remarkable dust control at an exhaust-to-pressure ratio of 0.8–1.0. With an increase in the air curtain jet angle, the dust control efficiency of the system first increased but subsequently decreased. In the present study, the appropriate air curtain jet angle was 10–20° for the developed soft-sealing system. In conclusion, when the air curtain outlet velocity, exhaust-to-pressure ratio, and jet angle were 6.27 m/s, 0.6, and 15°, respectively, the dust control efficiency of the developed soft-sealing system reached 92.6%. Unlabelled Image • Soft sealing with air curtain at open dust area could suppress dust escape. • Dust could be controlled and collected by orderly combination of air curtain. • The greater air supply and suction, the clearer the boundary of tracing column. • The dust control efficiency could reach 92.6%. [ABSTRACT FROM AUTHOR]

• Effects of particle size and the particle-falling-tube diameter on induced airflow were quantized. • Temporal and spatial distribution of free-falling grain with a particle size range of 3.247–9.223 mm is analyzed. • Semi-empirical equation for calculating induced airflow is established. • Semi-empirical equation is validated by experimental data. Airflow induced by falling particles can be a significant factor in causing dust emission during the conveyance of bulk materials. Heretofore, there have been few experimental studies on the effect of the particle size and the diameter of the tubes through which they are falling on the induced airflow. This study involved the experimental analysis of the correlation between those two factors and the induced airflow. The results were as follows: within the range of the total drag coefficient (0.62–0.94) of the experimental setup, the induced airflow velocity increased with an increment of the mass flow rate of the particles and drop height, and the power exponents of a fitted curve were approximately 0.35 and 1.29, respectively. Within the particle diameter range of 3.247–9.223 mm, the power coefficients and power exponents of a fitted curve for induced airflow velocity increased from 0.224 and 0.269 to 0.458 and 0.384, respectively, with the increase in particle size. As the tube diameter decreased from 200 mm to 120 mm, both the induced airflow velocity and the quantity of specific induced airflow increased, while the quantities decreased when the tube diameter decreased from 120 mm to 75 mm. The semi-empirical equation of the induced airflow velocity was established to predict the quantity of induced airflow under various operation conditions. [ABSTRACT FROM AUTHOR]

A column dust scrubber based on an orifice plate is developed for small and medium‐sized enterprises in China, which urgently need small‐volume, large‐flow scrubbers. The scrubber uses an orifice plate to evenly distribute the gas flow, which forms a uniform and stable impact on the liquid phase. As a result, dust removal via intensified gas‐liquid mixing can be achieved. A laboratory orifice plate scrubber model is developed, prototyped, and preliminarily studied considering the working process of the scrubber (mixed gas‐liquid flow pattern), liquid level, gas flow rate, pressure drop characteristics, dust removal efficiency, etc. The scrubber can achieve a good gas‐liquid mixing state when it is in a stable liquid column flow pattern. The drag coefficient of the scrubber is affected by the discharge of the gas stream to the liquid phase. [ABSTRACT FROM AUTHOR]

• The use of CR-ACVA for incipient fault detection. • The use of data captured from two operational industrial centrifugal pumps. • The combination of canonical residuals and recursive canonical variate analysis. • Early fault detection for the case of time-varying dynamic processes. • Comparison with existing techniques for incipient fault detection. Condition monitoring signals obtained from rotating machines often demonstrate a highly non-stationary and transient nature due to internal natural deterioration characteristics of their constituent components and external time-varying operational conditions. Traditional multivariate statistical monitoring approaches are based on the assumption that the underlying processes are linear and static and are apt to interpret the normal changes in operating conditions as faults, which would result in high false positive rates. On the other hand, the development of robust diagnostic techniques for the detection of incipient faults remains a challenge for researchers, given the difficulty of finding an appropriate trade-off between a low false positive ratio and early detection of emerging faults. To address these issues, this paper proposes a novel adaptive fault detection approach based on the canonical residuals (CR) induced by the combination of canonical variate analysis (CVA) and matrix perturbation theory for the monitoring of dynamic processes where variations in operating conditions are incurred. The canonical residuals are calculated based upon the distinctions between past and future measurements and are able to effectively detect emerging faults while still maintaining a low false positive rate. The effectiveness of the developed diagnostic model for the detection of abnormalities in industrial processes was demonstrated for slow involving faults in case studies of two operational industrial high-pressure pumps. In comparison with the variable-based and canonical correlation-based statistical monitoring approaches, the proposed canonical residuals-adaptive canonical variate analysis (CR-ACVA) fault detection method has demonstrated its superiorities by the detailed performance comparisons. [ABSTRACT FROM AUTHOR]

Photochromic core structure, triangle terthiophene, is configured to the design of 2,3-Bis(2,5-dimethylthiophen)-5-methoxyphenylethynylthiophene (PT) and 2,3-Bis(2,5-dimethylthiophen)-5-(4-methoxyphenyl)-1,3-butadiene-1,1,4,4-tetracarbonitrile(MPT) and characterized by NMR and HRMS technology. The photochromic behavior is investigated in typical solvents. With PT in hexane, reversibly photochromic process is induced by alternative irradiation of UV and Visible light. The solution color of PT can be toggled between colorless and pink, forming a switch cycle. In chloroform, the photochromic wavelength moves to shorter wavelength side. For MPT, UV light induced photochromism is not observed. Due to the addition of tetracarbonitrile, its strong electron-withdrawing character significantly lowers the electron density on reactive carbon atoms in LUMO, which is one of the key elements to support the photoactive of photochromism. Therefore, the molecular configuration of electron distribution is important to the design of photochromic dyes. [ABSTRACT FROM AUTHOR]

Nucleus pulposus cells (NPCs) play a vital role in maintaining the homeostasis of the intervertebral disc (IVD). Previous studies have discovered that NPCs exhibited malfunction due to cellular senescence during disc aging and degeneration; this might be one of the key factors of IVD degeneration. Thus, we conducted this study in order to investigate the altered biofunction and the underlying genes and pathways of senescent NPCs. We isolated and identified NPCs from the tail discs of young (2 months) and old (24 months) SD rats and confirmed the senescent phenotype through SA-β-gal staining. CCK-8 assay, transwell assay, and cell scratch assay were adopted to detect the proliferous and migratory ability of two groups. Then, a rat Gene Chip Clariom™ S array was used to detect differentially expressed genes (DEGs). After rigorous bioinformatics analysis of the raw data, totally, 1038 differentially expressed genes with a fold change>1.5 were identified out of 23189 probes. Among them, 617 were upregulated and 421 were downregulated. Furthermore, Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis were conducted and revealed numerous number of enriched GO terms and signaling pathways associated with senescence of NPCs. A protein-protein interaction (PPI) network of the DEGs was constructed using the Search Tool for the Retrieval of Interacting Genes (STRING) database and Cytoscape software. Module analysis was conducted for the PPI network using the MCODE plugin in Cytoscape. Hub genes were identified by the CytoHubba plugin in Cytoscape. Derived 5 hub genes and most significantly up- or downregulated genes were further verified by real-time PCR. The present study investigated underlying mechanisms in the senescence of NPCs on a genome-wide scale. The illumination of molecular mechanisms of NPCs senescence may assist the development of novel biological methods to treat degenerative disc diseases. [ABSTRACT FROM AUTHOR]

Air curtains have been thus far widely applied in thermal-insulation and dust-isolation sites. However, in some application scenarios that have strict constraints on the volume of the air curtain generator, the relations of the volume lower limit of the generator with the uniformity of the formed air curtain were poorly investigated. This study focused on small-volume transverse-flow air curtain generator, performed experiments and FLUENT numerical simulations for investigating the effects of three structural parameters, namely the cross-sectional area of the air curtain generator, the air supply groove and the diversion blades, on the uniformity, diffusivity and deviation of the formed air curtain. Results reveal that the cross-sectional area of the air curtain generator can directly affect the uniformity of the formed air curtain. By increasing the cross-sectional area, the static pressure difference in the air curtain generator along the full-length direction can be reduced and the uniformity of the air curtain can be enhanced. Under the premise that the constraints of the volume upper limit of the air curtain generator had to be satisfied, the optimal cross-section diameter of the air curtain generator was determined to be 110 mm. The use of the air supply groove with an appropriate length can effectively suppress the turbulence of the airflow at the outlet, weaken the entrainment effect of the jets on surrounding air and make the formed air curtain more concentrated. This study proves that an air supply groove with a length of 35 mm can satisfy the present requirements. In addition, the diversion blades can play the role of mechanical diversion so as to strengthen the turning of airflow and cope with serious deviations of the air curtain. In this study, using diversion blades with a spacing of 60 mm, the formed air curtain was nearly horizontal. Unlabelled Image • Structural parameters of air curtain generator affect performance of air curtain. • Increasing the cross-section area will improve the uniformity of air curtain. • The air supply groove could contribute to the formation of a concentrated air curtain. • Diversion blades could improve the anti-deviation capacity of air curtain. [ABSTRACT FROM AUTHOR]

The spatial distribution of the collectors in dust scrubber is key in determining the effectiveness of the dust removal process. In the present study, a high-speed camera was used to capture images of the distribution of the collectors. Some of the image information was extracted by image processing, such as the gray mean (GM), the angular second moment (ASM), and the entropy (ENT) from the gray-level co-occurrence matrix of the image. Subsequently, the spatial distribution rules of the collectors were studied by analyzing the spatial proportion, dispersion area, and uniformity and intensiveness of the collectors. It is an intuitive approach and a novel analysis method for the operating state of dust scrubber. The results show that the spatial distribution of the collectors could be better reflected by image processing methods. The dispersion area of the collectors expanded with an increase in the airflow velocity. When the initial liquid level (ILL) was higher, the collectors expanded in an approximate circular shape, and when the ILL was lower the collectors expanded in an approximate sector shape. In general, the variation trend in the spatial proportion enhanced with an increase in ILL and airflow velocity, which is consistent with the uniformity of collectors. When the liquid level was 0−20 mm and the airflow velocity was greater than 6.5 m/sec, the spatial proportion and uniformity of the collectors reached the highest degree. However, the growth rate of the spatial proportion and uniformity of the collectors slowed down and even led to negative growth when the ILL was lower and the airflow velocity was higher. The intensiveness of the collectors was great when the ILL was higher, which was free from the apparent influence of the airflow velocity and the ILL. However, when the ILL was lower, the intensiveness of the collectors was poor, intensifying as the airflow velocity and ILL increased. When the liquid level was −5−10 mm and the airflow velocity was greater than 8 m/sec, the intensiveness of the collectors reached the highest degree, indicating that a liquid level greater than 0 mm and a higher airflow velocity improved the spatial distribution of the collectors. Implications: This paper focuses on the spatial distribution of the collectors in dust scrubber. Some of the image information was extracted by image processing, such as the gray mean of the image, the angular second moment, and the entropy from the gray-level co-occurrence matrix of the image. The spatial distribution rules of the collectors were studied by analyzing the spatial proportion, the dispersion area, and the uniformity and intensiveness of the collectors. [ABSTRACT FROM AUTHOR]

• The development of a new monitoring index based on statistics T 2 , Q and T d. • The development of a CVR-based contribution method for the monitoring of slowly evolving faults. • Validated using data captured from a CSTR simulation program and an operational industrial centrifugal pump. The superior performance of canonical variate analysis (CVA) for fault detection has been demonstrated by a number of researchers using simulated and real industrial data. However, applications of CVA to fault identification of industrial processes, especially for faults that evolve slowly, are not widely reported. In order to improve the performance of traditional CVA-based methods to slowly developing faults, a novel diagnostic approach is put forward to implement incipient fault diagnosis for dynamic process monitoring. Traditional CVA fault detection approach is extended to form a new monitoring index based on indices, Hotelling's T 2 , Q and a canonical variate residuals (CVR)-based monitoring index T d. As an alternative to the traditional CVA-based contributions, a CVR-based contribution plot method is proposed based on Q and T d statistics. The proposed method is shown to facilitate fault detection by increasing the sensitivity to incipient faults, and aid fault identification by enhancing the contributions from fault-related variables and suppressing the contributions from fault-free variables. The CVR-based method has been demonstrated to outperform traditional CVA-based diagnostic methods for fault detection and identification when validated on slowly evolving faults in a continuous stirred tank reactor (CSTR) system and an industrial centrifugal pump. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Three novel Li 2 B phases are proposed. • These Li 2 B phases are more energy stable than Cmcm -Li 2 B at ambient pressure. • oC12–Li 2 B may be experimentally synthesized under ambient pressure. • hP6–Li 2 B has potential superconductivity. Abstract Few experimental and theoretical superconductivity works have focused on Li–B systems under the Li-rich regime. Here, we utilized the recently developed particle-swarm optimization method for structural search to propose three novel Li 2 B phases. These phases include the layered sandwich structure hP6–Li 2 B (P-3m1 , 164) and the two chain structures mS12–Li 2 B (C2/m , 12) and oC12–Li 2 B (Cmcm , 63). The structural stability of the three novel Li 2 B phases was confirmed on the basis of elastic constant and phonon dispersion calculations. Under ambient pressure, the three Li 2 B structures are notably more thermodynamically stable than the previously proposed Cmcm -Li 2 B structure and oC12–Li 2 B may be experimentally synthesized by α -LiB and Li. Electronic band structure and partial density of states analyses showed that our three proposed phases were metallic. The quasi-2D character in the band structure of hP6–Li 2 B was consistent with that of MgB 2 and indicated that hP6–Li 2 B has potential superconductive properties. Our electron–phonon coupling calculations illustrated that mS12– and oC12–Li 2 B exhibited superconductivity at 0.03 K under 10 Gpa and 0.14 K under 0 Gpa, respectively. Moreover, we found that hP6–Li 2 B has low superconductivity with a predicted T c of 0.09 K at 20 GPa, and its λ and T c values increased within the pressure range of 20–50 GPa and then decreased under pressures exceeding 60 GPa. The maximum λ and T c values under 60 GPa were 0.33 and 0.65 K, respectively. [ABSTRACT FROM AUTHOR]

A new BODIPY dye with terthiophene branched is configured by Sonogashira coupling and fully characterized by NMR and MS. In general organic solvents, it emits typical green fluorescence ranging in 513-518 nm, like most BODIPY analogues. The terthiophene substitution is greatly improved and the emission peak does not sensitive to the polarity environment. More importantly, the terthiophene plays the role of antenna, harvesting the 340 nm's excitation energy and transferring the energy to BODIPY efficiently. Even though the molar extinction coefficient in 340 nm is lower than that of maximum absorption, it can enlarge the pseudo Stoke's shift to ∼170 nm, well separating the excitation and emission. In film, the emission shifted to 562 nm due to the polymer chain dissipation part of the energy. It shifted further to 585 nm in solid. The branched terthiophene configures a twisted molecular conformation, which avoids the dye regular packing. Highly emission, excellent solubility and stability constitute the general character of the thiophene attached BIDIPY dye. [ABSTRACT FROM AUTHOR]

Dipyrrolydiketones BF2 complex was obtained by a simple synthesis and routinely characterized by NMR and HRMS technology. This BF2 containing dye shows strong emission in chloro-carbon solvents, for example chloroform, toluene, with the emission maximum in the blue-green region. No significant absorption or emission shift is observed in the spectra investigation. The rigid molecular framework contributes to it's highly emission character, which limited the energy dissipation to the environment. The emission quantum yield ranged from 0.23 to 0.42. In polycarbonate film, the emission shifted to longer wavelength 539 nm. In solid state, the emission shifted toward red furtherly (580 nm) and broadened the emission band significantly, demonstrating a strong intermolecular interaction. Emission decay also exhibited bicxponential declining kinetics. In all the case, the emission colors were demonstrated by International Commission on Illumination (CIE) chromaticity system. [ABSTRACT FROM AUTHOR]

In this contribution, an F-B containing dye is readily synthesized. In chloro-carbon medium, it exhibit good solubility and stability. The emission peak value is determined to be 519 nm in chloroform. The highly emissive character is ascribed to the coordination lock, which inhibits the free rotation of methoxybenzene around the single bond. This BF2 locker inhibits the energy dissipation by thermal vibration to an extent and results strong fluorescence emission. In addition, electron deficiency feature of B atom also contributes to its strong emission character. Even though the π-conjugate system is small, the emission shifted significantly and the Stoke's shift reaches to 170 nm. In addition, the film by doping into polycarbonate is also emissive. In solid state, the emission maximum reaches to 529 nm. Both in film and in solid, only slightly redshift are observed, demonstrating less interference of intermolecular interaction toward the excited dye molecules. [ABSTRACT FROM AUTHOR]

Reciprocating compressors are widely used in oil and gas industry for gas transport, lift and injection. Critical compressors that compress flammable gases and operate at high speeds are high priority equipment on maintenance improvement lists. Identifying the root causes of faults and estimating remaining usable time for reciprocating compressors could potentially reduce downtime and maintenance costs, and improve safety and availability. In this study, Canonical Variate Analysis (CVA), Cox Proportional Hazard (CPHM) and Support Vector Regression (SVR) models are employed to identify fault related variables and predict remaining usable time based on sensory data acquired from an operational industrial reciprocating compressor. 2-D contribution plots for CVA-based residual and state spaces were developed to identify variables that are closely related to compressor faults. Furthermore, a SVR model was used as a prognostic tool following training with failure rate vectors obtained from the CPHM and health indicators obtained from the CVA model. The trained SVR model was utilized to estimate the failure degradation rate and remaining useful life of the compressor. The results indicate that the proposed method can be effectively used in real industrial processes to perform fault diagnosis and prognosis. [ABSTRACT FROM AUTHOR]

Centrifugal compressors are widely used for gas lift, re-injection and transport in the oil and gas industry. Critical compressors that compress flammable gases and operate at high speeds are prioritized on maintenance lists to minimize safety risks and operational downtime hazards. Identifying incipient faults and predicting fault evolution for centrifugal compressors could improve plant safety and efficiency and reduce maintenance and operation costs. This study proposes a dynamic process monitoring method based on canonical variable analysis (CVA) and long short-term memory (LSTM). CVA was used to perform fault detection and identification based on the abnormalities in the canonical state and the residual space. In addition, CVA combined with LSTM was used to estimate the behavior of a system after the occurrence of a fault using data captured from the early stages of deterioration. The approach was evaluated using process data obtained from an operational industrial centrifugal compressor. The results show that the proposed method can effectively detect process abnormalities and perform multi-step-ahead prediction of the system’s behavior after the appearance of a fault. [ABSTRACT FROM AUTHOR]

In this contribution, the emission response of 4-(2,5-dimethylthiophen-3-yl)-2-(2-hydroxy- phenyl)benzothiazole (THBT) was investigated in detail. The experimental shows that Zn2+ could induce fluorescence increasing in tetrahydrofuran (THF). Especially, the quenched emission of THBT was significantly enhanced with 0.76 quantum yield. Due to the coordination of Zn2+, the excited state intramolecular proto transfer (ESIPT) was inhibited and leads to emission quenching correspondingly. The strong emission could ascribe to the Zn-THBT complex. As well, the addition of BF3·Et2O also could form fluorine-boron complex and inhibit ESIPT effect. Additionally, the BF complex is also a strong blue emitter. Therefore, strong blue emission upon BF3·Et2O addition to THBT in dioxane was found. The possible coordinating mechanisms of THBT coordinate with Zn2+ and BF3·Et2O were given. [ABSTRACT FROM AUTHOR]

An electron acceptor, malononitrile, was attached to bisthienylethene derivative. The significant influence of electron nature result a reversed phtochromism. Investigation of MT in THF demonstrates the reversible ring-open and ring-close. Upon irradiation of 405 nm laser, the solution color changed from yellowish to colorless, which is different from most of the photochromic colored phenomenon. Upon 254 nm irradiation, the original yellowish state can be recovered. Due to the attachment of malononitrile, the photo-/thermal-stability were enhanced. The ring-open/ring-closed forms were optimized by Dmol3. The distance between photocyclizing atoms in aptiparallel conformation meets the requirement for photochromic reaction. And the calculated absorption values were also in agreement with the experimental ones. [ABSTRACT FROM AUTHOR]

A novel BODIPY-based dye with highly emissive character was configured by Sonogashira coupling and routinely characterized by NMR and MS technology. The emission of dye was investigated in solution/film/solid and shows intensive emission. In solution, the emission peak appeared around 510 nm with little influence by the polar environment. The terthiophene plays an effective antenna effect, harvesting the light and transferring the energy to BODIPY. The pseudo Stoke's shift enlarged to ∼170 nm in solution. In film, the emission peak shifted to 563 nm in polycarbonate matrix. And it shifted further to 585 nm in solid due to the highly twisted structure, which avoided closely regular-tight packing. The dye rendered an intense fluorescence, good optothermal stability, and high fluorescence quantum yield (0.55). The solid emission showed highly red emission with Commission Internationale de L'Eclairage (CIE) coordinates of (X = 0.69, Y = 0.31). Thus, the synthesized dye is idea candidate for emitting materials. [ABSTRACT FROM AUTHOR]

In this contribution, a dye (C8-alkyl substituted Naphthalimide-Coumarin, CNC) with naphthalimide and coumarin incorporated together with -NHN = bridge unit. The compound was fully characterized by NMR and HRMS spectroscopic techniques. Highly emissive character was investigated in detail in various polar environments. The emission maximum varied from 430 to 470 nm. In polycarbonate film, CNC is also highly emissive with 560 nm emission peak. While in sold, the emission maximum was further shifted to 580 nm due to the more tightly packing mode than that in film. The C8-alkyl substitution enhances the solubility of CNC and also contributes most to its solid emission. [ABSTRACT FROM AUTHOR]

Calcium intercalates of MoS 2 with nominal composition Ca x MoS 2 (0 ≤ x ≤ 0.50) were prepared in liquid ammonia. Ammonia molecules were also intercalated into MoS 2 along with Ca as revealed by thermogravimetric and gravimetric analysis. The intercalated products have a composition of Ca x (NH 3 ) y MoS 2 (0 ≤ y ≤ 0.40). The crystal structure of Ca 0.50 (NH 3 ) 0.40 MoS 2 was solved and refined from powder X-ray diffraction data. It exhibits a hexagonal symmetry (space group P -3 m 1) with a = 3.198(4) Å, c = 18.543(9) Å. The crystal structure of Ca 0.50 (NH 3 ) 0.40 MoS 2 was also investigated by Raman spectroscopy and transmission electron microscopy. Superstructure in the ab-plane and phase transition from 2H to 1T were not observed. Only samples with x in the range from 0.10 to 0.35 show superconducting properties and the T c - x phase diagram of the Ca x (NH 3 ) y MoS 2 system exhibits a dome-like behavior. The maximum T c of 8.6 K was observed in Ca 0.20 (NH 3 ) 0.17 MoS 2 , which is higher than the T c reported before in chemically doped transition metal dichalcogenides. The Ca 0.20 (NH 3 ) 0.17 MoS 2 is a type-II superconductor with H c2 (0) around 0.098 T and ξ (0) about 58.0 nm. [ABSTRACT FROM AUTHOR]

In this article, a dye with naphthalimide and coumarin was configured and was fully characterized. Its emission behavior was investigated in medium polar solvent. The emission behavior shows that there is no obvious energy transfer between naphthalimide and coumarin. Therefore, both the emission of naphthalimide and coumarin exhibit in the emission spectra, including blue and yellow part. The emission in film and solid shows different character. In film, single emission peak was observed. However, the solid emission covered a broad scope, including blue and yellow integrant. All the emission color was indicated by (Commission Internationale de L'Eclairage) CIE coordinates. The CIE coordinate of solid emission (0.29, 0.33) is approaching the ideal white light. [ABSTRACT FROM AUTHOR]

In order to address the bottleneck problem of low fine-particle removal efficiency of self-excited dust scrubbers, this paper is focused on the influence of the intermittent gas-liquid two-phase flow on the mesoscale behavior of collector aggregations. The latter is investigated by the application of high-speed dynamic image technology to the self-excited dust scrubber experimental setup. The real-time-scale monitoring of the dust removal process is provided to clarify its operating mechanism at the mesoscale level. The results obtained show that particulate capturing in self-excited dust scrubber is provided by liquid droplets, liquid films/curtains, bubbles, and their aggregations. Complex spatial and temporal structures are intrinsic to each kind of collector morphology, and these are considered as the major factors controlling the dust removal mechanism of self-excited dust scrubbers. For the specific parameters of gas-liquid two-phase flow under study, the evolution patterns of particular collectors reflect the intrinsic, intermittent, and complex characteristics of the temporal structure. The intermittent initiation of the collector and the air hole formation-collapse cyclic processes provide time and space for the fine dust to escape from being trapped by the collectors. The above mesoscale experimental data provide more insight into the factors reducing the dust removal efficiency of self-excited dust scrubbers. Implications: This paper focuses on the reconsideration of the capturer aggregations of self-excited dust scrubbers from the mesoscale. Complex structures in time and space scales exist in each kind of capturer morphology. With changes of operating parameters, the morphology and spatial distributions of capturers diversely change. The change of the capturer over time presents remarkable, intermittent, and complex characteristics of the temporal structure. [ABSTRACT FROM AUTHOR]

In this article, a BF2-containg dye was configured and routinely characterized by 1H NMR and MS technology. This BF-cored dye shows intensive emission in chloro-carbon solvents, for example dichloromethane, with the emission peak 475 and 515 nm. The emission profiles almost the mirror image of the absorption of profile. The highly emissive character may ascribe to the coordinate lock, which limited the free rotation of benzene ring and nonradiation transition. Therefore, the dye exhibits highly emissive character. Even if the molecular framework is small, a larger Stoke's shift (170 nm) was observed. Additionally, the emission in film shifts 5 nm more than that in solution. In solid state, the emission maximum reached to 525 nm. In all the case, the emission colors were demonstrated by International Commission on Illumination (CIE) chromaticity system. [ABSTRACT FROM AUTHOR]

Photochromic diarylethene oxime isomers were obtained by coupling between hydroxylamine hydrochloride and 2,3-bis(2,5-dimethylthiophene-3-yl)thiophene-5-carbaldehyde. The two isomers were confirmed by NMR. Photochromic behavior was investigated in THF. Reversible photochromism could be induced by alternated UV/Visible light. The solution color also can be toggled between colorless and light purple. Corresponding photo- and thermo-stability measurements indicate that they are stable in the dark at room temperature. However, the degradation of the two isomers is accelerated with the temperature rising and prolonged exposure to UV light. Optimized geometry structure and frontier molecular orbitals further supported their photochromic activity. [ABSTRACT FROM PUBLISHER]

A BODIPY based with perimidine attached derivative was developed and characterized. It was efficiently synthesized by condensation between aldehyde sited at β-position of BODIPY and 1,8-diamino-naphthalene. Owing to the electron-donor effect of N in heterocycle, emission was quenched completely. Upon protonation of N, the solution exhibited dramatic emission enhancement with emission peak locating at 510 nm, which is estimated to be 275-fold of initial emission. With OH−addition, it could be reverted to the emission to non-emisison state again and establish a fluorescence switch. The underlying mechanism of fluorescence “off-on” is based on the intramolecular PET, which was attested by quantum chemistry calculation approach. [ABSTRACT FROM PUBLISHER]

A photochromic triangle terthiophene with phenylethynyl attached was synthesized under Sonogashira coupling condition and fully characterized. The photochromic behavior was investigated in typical solvents. In hexane, the reversibly photochromic process was induced by UV and Visible light. The solution color could be toggled between colorless and pink color. The photo- and thermo-stability were also investigated at 273 and 323 K. It is stable in the dark at the room temperature, while the degradation accelerated with the temperature rising. Correspondingly, the optimized geometry structure and frontier molecular orbitals were calculated. Both the distance between reactive carbon atoms and the HOMO distribution of ring-open form support the photo-cyclization reaction. [ABSTRACT FROM PUBLISHER]

A new red-fluorescent BODIPY derivative is designed and synthesized, which is configured by attaching an electron-withdrawing unit 2-dicyanomethylene-3-cyano-4,5,5-trimethyl-2,5-dihydrofuran (TCF). By virtue of the strong electron-accepting nature of TCF unit, the compound BT exhibits a large red-shift both in absorption and emission. In contrast to parent BODIPY, the absorption shifted about 90 nm. And the emission maximum shifted to red region with the peak centered around 620 nm. The CIE coordinate and fluorescence decay data uncovered its emission character. Theoretical calculation of BT confirmed that the electron density was altered dramatically by TCF and lowered the energy gap between ground state. The character of HOMO/LUMO distribution is well in agreement with that of experimental value. [ABSTRACT FROM PUBLISHER]

A propeller conformed triphenylamine molecule was decorated with naphthalimide. The two fluorophores were bonded with alkynyl bridge unit, which conjugates the two fragments. The resulting compound was fully characterized. Several solvents were used to investigate its absorption and emission behavior with the solvent polarity variation from weak to strong. The quantum yield increased with the increasing of solvent polarity. It is also highly emissive in film and in a solid with significant emission shift toward longer wavelength, reaching to 544 and 593 nm, respectively. The underlying signal mechanism was interpreted by the HOMO/LUMO potentials based on TDDFT calculations. [ABSTRACT FROM PUBLISHER]

Naphthalimide and coumarin were bonded together with –NHN= being as the linkage. The emission behavior was investigated in various solvents. The energy transfer is independent in weak and medium polarity solvents. Efficient energy transfer occurred with the emission of it in polar solvent. In addition, it is highly emissive in polycarbonate and the energy transfer from coumarin to naphthalimide is more efficient. Another significant feature is its selective F−response. Upon the F−addition, the absorption around 444 nm shifted to 486 nm. And the new absorption band decreased and another new absorption band appeared around 574 nm. [ABSTRACT FROM AUTHOR]

Detailed absorption and emission behavior were investigated for a sexthiophene molecule in solution, film, and solid. Only strong polarity solvent could result a notable influence on the quench of its fluorescence. In weak and medium polar environment, including in polymer matrix, highly emissive behavior was maintained and exhibit large Stokes shift. More important is its highly emissive in solid state due to the twisted molecular conformation. However, the bandwidth of solid emission (FWHM: 2149 cm−1) is similar to that of solution emission. The calculated frontier orbital based on TDDFT theory uncovered the underlying signal mechanism furtherly. [ABSTRACT FROM AUTHOR]