The pyrolysis kinetics of charring materials plays an important role in understanding material combustions especially for construction materials with complex degradation chemistry. Thermogravimetric ...analysis (TGA) is frequently used to study the heterogeneous kinetics of solid fuels; however, there is no agreed method to determine the pyrolysis scheme and kinetic parameters for charring polymers with multiple components and competing reaction pathways. This study develops a new technique to estimate the possible numbers of species and sub-reactions in pyrolysis by analyzing the second derivatives of thermogravimetry (DDTG) curves. The pyrolysis of a medium-density fiberboard (MDF) in nitrogen is studied in detail, and the DDTG curves are used to locate the temperature of the peak mass-loss rate for each sub-reaction. Then, on the basis of the TG data under multiple heating rates, Kissinger’s method is used to quickly find the possible range of values of the kinetic parameters (A and E). These ranges are used to accelerate the optimization of the inverse problem using a genetic algorithm (GA) for the kinetic and stoichiometric parameters. The proposed method and kinetic scheme found are shown to match the experimental data and are able to predict accurately results at different heating rates better than Kissinger’s method. Moreover, the search method (K–K method) is highly efficient, faster than the regular GA search alone. Modeling results show that, as the TG data available increase, the interdependence among kinetic parameters becomes weak and the accuracy of the first-order model declines. Furthermore, conducting TG experiment under multiple heating rates is found to be crucial in obtaining good kinetic parameters.
Efficient multifunctional materials acting as violet‐blue emitters, as well as host materials for phosphorescent OLEDs, are crucial but rare due to demand that they should have high first singlet ...state (S1) energy and first triplet state (T1) energy simultaneously. In this study, two new violet‐blue bipolar fluorophores, TPA‐PI‐SBF and SBF‐PI‐SBF, were designed and synthesized by introducing the hole transporting moiety triphenylamine (TPA) and spirobifluorene (SBF) unit that has high T1 into high deep blue emission quantum yield group phenanthroimidazole (PI). As the results, the non‐doped OLEDs based on TPA‐PI‐SBF exhibited excellent EL performance with a maximum external quantum efficiency (EQEmax) of 6.76 % and a violet‐blue emission with Commission Internationale de L′Eclairage (CIE) of (0.152, 0.059). The device based on SBF‐PI‐SBF displayed EQEmax of 6.19 % with CIE of (0.159, 0.049), which nearly matches the CIE coordinates of the violet‐blue emitters standard of (0.131, 0.046). These EL performances are comparable to the best reported non‐doped deep or violet‐blue emissive OLEDs with CIEy<0.06 in recent years. Additionally, the green, yellow and red phosphorescent OLEDs with TPA‐PI‐SBF and SBF‐PI‐SBF as host materials achieved a high EQEmax of about 20 % and low efficiency roll‐off at the ultra‐high luminance of 10 000 cd m−2. These results provided a new construction strategy for designing high‐performance violet‐blue emitters, as well as efficient host materials for phosphorescent OLEDs.
The non‐doped device based on TPA‐PI‐SBF as emitter exhibited a maximum external quantum efficiency (EQEmax) of 6.76 % with Commission Internationale de L′Eclairage (CIE) of (0.152, 0.059). As host material, the green, yellow, and red phosphorescent OLEDs obtained high EQEmax of about 20 % and both devices exhibited low efficiency roll‐off.
Solar energy application in a wider spectrum has the potential for high efficiency energy conversion. However, solar cells can only absorb photon energy of the solar spectrum near the solar cell ...band-gap energy, and the remaining energy will be converted into thermal energy. The thermoelectric generator is a good choice to utilize this thermal energy. This paper analyses the feasibility of photovoltaic-thermoelectric (PV-TE), and reviews the current types and performance of PV-TE. Furthermore, it presents the optimization and development of PV-TE. In addition, this paper presents the challenge and efficient improvement of PV-TE in actual application. Therefore, this paper would provide a valuable reference for further research into the field of PV-TE and its applications.
•The performance and recent advances in PV-TE are presented.•The challenge faced in the field of PV-TE and solutions are indicated.•Current state of art in PV-TE for electricity generation is presented.•Optimization and development of PV-TE is demonstrated.
•Migration phenomenon of TE load resistance for PV-TE was indicated.•The model of the PV-TE was built and verified.•PV-TE based on two types of PV cells were analyzed.•The load resistances in ...different ambient conditions were compared.
Combing PV with Thermoelectric (TE) would be dominant because it can employ the solar fully spectrum to produce electricity. But the TE efficiency is significantly lower than PV efficiency and the coupling effect between them will limit the performance of PV and TE. The analyze and comparison on the different characteristics among the hybrid module, the PV alone and TE alone is significant to obtain the highest the electrical efficiency. In this paper, the attention was paid to the inconsistent phenomenon of thermoelectric load resistance for photovoltaic–thermoelectric modules. The model of PV-TE was built and verified based on two types of PV cells. The load resistance of TE for the maximum power output was also analyzed under different working conditions for the TE alone, TE in the PV-TE and PV-TE. The results showed that the load resistance of TE for the maximum power output of the TE alone, TE in the PV-TE and PV-TE are all different. For example, the PV-TE module based on the c-Si cell attains its peak value at the load electrical resistance of TE of 0.75 Ω, while the internal electrical resistance of the TE is 0.47 Ω. The PV-TE module based on the GaAs cell shows a maximum efficiency of PV-TE with a load resistance of approximately 1.6 Ω, while the internal electrical resistance of the TE is 2.0 Ω. Referring to the load resistance of TE alone is not suitable for PV-TE maximum power output. In addition, the TE maximum power output does not correspond to the PV-TE maximum power output since the TE load resistances in these two conditions are also different. The study will provide the reference for attaining the correct load resistance for the actual maximum power output of PV-TE module.
Photoreceptors are electrically coupled to one another, and the spatiotemporal properties of electrical synapses in a two-dimensional retinal network are still not well studied, because of the ...limitation of the single electrode or pair recording techniques which do not allow simultaneously measuring responses of multiple photoreceptors at various locations in the retina. A multiple electrode recording system is needed. In this study, we investigate the network properties of the two-dimensional rod coupled array of the salamander retina (both sexes were used) by using the newly available multiple patch electrode system that allows simultaneous recordings from up to eight cells and to determine the electrical connectivity among multiple rods. We found direct evidence that voltage signal spread in the rod-rod coupling network in the absence of
(mediated by HCN channels) is passive and follows the linear cable equation. Under physiological conditions,
shapes the network signal by progressively shortening the response time-to-peak of distant rods, compensating the time loss of signal traveling from distant rods to bipolar cell somas and facilitating synchronization of rod output signals. Under voltage-clamp conditions, current flow within the coupled rods follows Ohm's law, supporting the idea that nonlinear behaviors of the rod network are dependent on membrane voltage. Rod-rod coupling is largely symmetrical in the 2D array, and voltage-clamp blocking the next neighboring rod largely suppresses rod signal spread into the second neighboring rod, suggesting that indirect coupling pathways play a minor role in rod-rod coupling.
The exploration of the complex chemical diversity of bicyclon.1.1alkanes and their use as benzene bioisosteres has garnered significant attention over the past two decades. Regiodivergent syntheses ...of thiabicyclo4.1.1octanes (S‐BCOs) and highly substituted bicyclo2.1.1hexanes (BCHs) using a Lewis acid‐catalyzed formal cycloaddition of bicyclobutanes (BCBs) and 3‐benzylideneindoline‐2‐thione derivatives have been established. The first hetero‐(4+3) cycloaddition of BCBs, catalyzed by Zn(OTf)2, was achieved with a broad substrate scope under mild conditions. In contrast, the less electrophilic BCB ester undergoes a Sc(OTf)3‐catalyzed 2π+2σ reaction with 1,1,2‐trisubstituted alkenes, yielding BCHs with a spirocyclic quaternary carbon center. Control experiments and preliminary theoretical calculations suggest that the diastereoselective 2π+2σ product formation may involve a concerted cycloaddition between a zwitterionic intermediate and E‐1,1,2‐trisubstituted alkenes. Additionally, the hetero‐(4+3) cycloaddition may involve a concerted nucleophilic ring‐opening mechanism.
Regiodivergent syntheses of thiabicyclo4.1.1octanes (S‐BCOs) and highly substituted bicyclo2.1.1hexanes have been achieved through a Lewis acid‐catalyzed cycloaddition of bicyclobutanes (BCBs) and 3‐benzylideneindoline‐2‐thione derivatives. Moreover, rapid access of S‐BCOs, which were not readily accessible by known methods, has been realized through Zn(OTf)2‐catalyzed uncommon 4π+2σ cycloadditions of BCBs.
The intraocular pressure inside the human eye maintains 10-21 mmHg above the atmospheric pressure. Elevation of intraocular pressure is highly correlated with the retinopathy in glaucoma, and changes ...in the exterior pressure during mountain hiking, air traveling, and diving may also induce vision decline and retinopathy. The pathophysiological mechanism of these pressure-induced retinal disorders has not been completely clear. Retinal neurons express pressure-sensitive channels intrinsically sensitive to pressure and membrane stretch, such as the transient receptor potential channel (TRP) family permeable to Ca2+ and Na+ and the two-pore domain K channel family. Recent data have shown that pressure excites the primate retinal bipolar cell by opening TRP vanilloid 4 to mediate transient depolarizing currents, and TRP vanilloid 4 agonists enhance the membrane excitability of primate retinal ganglion cells. The eyeball wall is constructed primarily by the sclera and cornea of low elasticity, and the flow rate of the aqueous humor and intraocular pressure both fluctuate, but the mathematical relationship between the ocular elasticity, aqueous humor volume, and intraocular pressure has not been established. This review will briefly review recent literature on the pressure-related retinal pathophysiology in glaucoma and other pressure-induced retinal disorders, the elasticity of ocular tissues, and pressure-sensitive cation channels in retinal neurons. Emerging data support the global volume and the elasticity and thickness of the sclera and cornea as variables to affect the intraocular pressure level like the volume of the aqueous humor. Recent results also suggest some potential routes for TRPs to mediate retinal ganglion cell dysfunction: TRP opening upon intraocular pressure elevation and membrane stretch, enhancing glutamate release from bipolar cells, increasing intracellular Na+, Ca2+ concentration in retinal ganglion cells and extracellular glutamate concentration, inactivating voltage-gated Na+ channels, and causing excitotoxicity and dysfunction of retinal ganglion cells. Further studies on these routes likely identify novel targets and therapeutic strategies for the treatment of pressure-induced retinal disorders.
Band offsets between different monolayer transition metal dichalcogenides are expected to efficiently separate charge carriers or rectify charge flow, offering a mechanism for designing atomically ...thin devices and probing exotic two-dimensional physics. However, developing such large-area heterostructures has been hampered by challenges in synthesis of monolayers and effectively coupling neighboring layers. Here, we demonstrate large-area (>tens of micrometers) heterostructures of CVD-grown WS2 and MoS2 monolayers, where the interlayer interaction is externally tuned from noncoupling to strong coupling. Following this trend, the luminescence spectrum of the heterostructures evolves from an additive line profile where each layer contributes independently to a new profile that is dictated by charge transfer and band normalization between the WS2 and MoS2 layers. These results and findings open up venues to creating new material systems with rich functionalities and novel physical effects.
Hepatocellular carcinoma (HCC) is a common primary malignant tumor which usually progresses to an advanced stage because of late diagnosis. Sorafenib (Sora) is a first line medicine for advanced ...stage HCC; however, it has been faced with enormous resistance. Simvastatin (Sim) is a cholesterol-lowering drug and has been reported to inhibit tumor growth. The present study aims to determine whether Sora and Sim co-treatment can improve Sora resistance in HCC.
The HCC cell line LM3 and an established Sora-resistant LM3 cell line (LM3-SR) were used to study the relationship between Sora resistance and aerobic glycolysis. Cell proliferation, apoptosis and glycolysis levels were analyzed by western blotting, flow cytometry analysis and biomedical tests. A xenograft model was also used to examine the effect of Sim in vivo. Detailed mechanistic studies were also undertaken by the use of activators and inhibitors, and lentivirus transfections.
Our results demonstrated that the resistance to Sora was associated with enhanced aerobic glycolysis levels. Furthermore, LM3-SR cells were more sensitive to Sim than LM3 cells, suggesting that combined treatment with both Sora and Sim could enhance the sensitivity of LM3-SR cells to Sora. This finding may be due to the suppression of the HIF-1α/PPAR-γ/PKM2 axis.
Simvastatin can inhibit the HIF-1α/PPAR-γ/PKM2 axis, by suppressing PKM2-mediated glycolysis, resulting in decreased proliferation and increased apoptosis in HCC cells, and re-sensitizing HCC cells to Sora.
A novel heat-pipe photovoltaic/thermal system was designed and constructed by the authors. This system can simultaneously supply electrical and thermal energy. In addition, when compared with the ...traditional water-type photovoltaic/thermal system, this system can be used in cold regions without freezing. A dynamic model was developed to predict the performances of the heat-pipe photovoltaic/thermal system. Experiments were also conducted to validate results obtained for the simulation. A comparison between simulation values and experimental results demonstrated that the model was able to yield satisfactory predictions. Results indicated that the daily thermal and electrical efficiencies of the heat-pipe photovoltaic/thermal system were 41.9% and 9.4%, respectively, while the average heat and electrical gains were 276.9 and 62.3
W/m
2, respectively. In addition, second-law efficiency, based on the second law of thermodynamics, is provided to analyze the total efficiency of the heat-pipe photovoltaic/thermal system, and the average total second-law efficiency of the system is 6.8%.
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