•A new design concept is proposed to enhance the maximum temperature drop across TECs.•The design combines cascade TEC with transient supercooling effect.•Effectiveness of the design is verified by a ...multiphysics and transient TEC model.•Pulse parameters and TEC geometry are examined to further improve supercooling.
In this work, a new design concept which combines two-stage design with transient supercooling effect is proposed to enhance the maximum temperature drop across thermoelectric coolers (TECs). A three-dimensional, multiphysics, and transient model is used to examine the design effectiveness. Step current pulses with various amplitudes (P) and widths (τ) are supplied to the two stages of a two-stage TEC in series. The results show that, as compared with the single-stage counterpart, a significant improvement in the maximum cold-end temperature drop (ΔTc,max) is observed for the two-stage TEC. Meanwhile, the new design also greatly reduces the temperature overshoot (Tc,max) and increases the holding time of supercooling state (Δthold). Subsequently, effects of the pulse amplitude, width, and shape are discussed and two important geometry parameters: the cross-sectional area ratio of p-type leg to n-type leg and the leg length ratio of cold stage to hot stage are investigated. These results confirm that ΔTc,max, Tc,max, and Δthold can be further improved by optimizing the pulse and the geometry parameters. This work provides a feasible cooling approach for some specific cooling targets, such as mid-infrared laser gas sensors or any other semiconductor devices which require a temporary but large temperature drop.
The output power and conversion efficiency of the thermoelectric generator (TEG) are closely related to not only the materials properties but also the geometric structure. This paper developed a ...multi-physics, steady-state, and three-dimensional numerical TEG model to investigate the TEG performance, and then the model is compared with the classical thermal resistance model. Bismuth-telluride are used as p- and n-type materials. The comparison reveals that the assumption of constant material properties leads to underestimated inner electrical resistance, and overestimated thermal conductance and Seebeck coefficient, so that the thermal resistance model predicts unrealistically high performance than the present model. The results also indicate that when heat losses exist between the TEG and the ambient, although the output power is slightly elevated, the conversion efficiency is significantly reduced, hence, improvement of the heat insulation effect is critically important for high-temperature TEGs. Furthermore, the TEG geometry also affects its performance significantly: usage of thin ceramic plates increases the junction temperature difference, and hence enhances the TEG performance; there are two optimal leg lengths which correspond to the maximum output power and the maximum conversion efficiency, respectively; when heat losses are not ignorable, a large semiconductor cross-sectional area remarkably reduces the ratio of the heat liberated to the ambient to the heat absorbed from the high-temperature heat source, and hence improves the conversion efficiency.
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•Functionalized PLLA porous fibers were fabricated by electrospinning.•The PLLA porous fibers exhibited good adsorption ability toward Congo red.•Excellent oil/water separation ...ability was achieved for the PLLA fiber membranes.•High efficiency in separating emulsified and non-emulsified oil/water systems.
In this work, novel functionalized poly(l-lactide) (F-PLLA) porous fibers were fabricated through electrospinning using the PLLA/methylene chloride (CH2Cl2)/N,N-dimethylformamide (DMF) solution containing diethylenetriamine (DETA) and γ-aminopropyltriethoxysilane (KH-550). The effects of PLLA, DETA and KH-550 contents on the morphologies of the electrospun fibers were systematically investigated, and the results showed that at PLLA, DETA and KH-550 contents of 20% w/v, 2 wt% and 3 wt%, respectively, the electrospun F-PLLA fibers exhibited the homogeneous distribution of fiber diameters and the homogeneous porous structure on the fiber surface. Nitrogen-containing groups were successfully introduced to the electrospun fibers, which induced the great improvement of the hydrophilicity of the membrane surface. Adsorption measurements showed that the electrospun F-PLLA membrane had good adsorption ability toward Congo red (CR), and the adsorption capacity at room temperature was enhanced in 16 times compared with the common PLLA fiber membrane, and the maximum adsorption capacity was 135.7 mg g−1. Furthermore, the adsorption behavior could be well described by the pseudo second-order model. Oil/water separating measurements showed that the electrospun F-PLLA membrane exhibited high separation efficiency and the maximum water fluxes were 2018 and 1861 L m−2 h−1 in separating non-emulsified and emulsified oil/water system under atmospheric pressure, respectively.
Immune checkpoint inhibitors (ICIs) have revolutionized cancer management and have been widely applied; however, they still have some limitations in terms of efficacy and toxicity. There are multiple ...treatment regimens in Traditional Chinese Medicine (TCM) that play active roles in combination with Western medicine in the field of oncology treatment. TCM with ICIs works by regulating the tumor microenvironment and modulating gut microbiota. Through multiple targets and multiple means, TCM enhances the efficacy of ICIs, reverses resistance, and effectively prevents and treats ICI-related adverse events based on basic and clinical studies. However, there have been few conclusions on this topic. This review summarizes the development of TCM in cancer treatment, the mechanisms underlying the combination of TCM and ICIs, existing studies, ongoing trials, and prospects for future development.
•A complete three-dimensional TEC transient model was proposed.•The model couples heat conduction and electric conduction.•Dynamic behaviors are studied at extensive operating ...conditions.•Temperature-dependent material properties have strong effect on dynamic behaviors.
Dynamic characteristics are extremely important for design and operation of thermoelectric coolers (TECs). This paper develops a three-dimensional transient TEC model based on the coupling of heat transfer and electric conduction within semiconductors. The model takes into account all thermoelectric effects, including Joule heating, Thomson effect, Peltier effect and Fourier’s heat conduction. For most of semiconductor materials, Seebeck coefficient, electric conductivity and thermal conductivity are strongly temperature-dependent. Therefore, the present transient model is used to compare dynamic temperature variations at the cold and hot ends with constant and variable material properties. Small, medium, and large applied currents with various cooling loads are adopted as operating conditions. The results show that, at small currents, constant property model developed by this work can predict accurately the dynamic characteristics, however, with the increase in current, the temperature-dependence of properties have more and more remarkable effect on the dynamic temperature variations, especially for high cooling loads. When the current is larger than a specific value, the heat transferred from the hot end to the cold end by Fourier’s heat conduction will exceed the heat adsorbed at the cold end by Peltier effect, thus, the temperatures at the cold and hot ends increase continuously, the TEC cannot reach the steady-state. This phenomena is predicted exactly by the variable property model, oppositely, the constant property model predicts that the TEC still supply refrigeration.
Polymer-based dielectric nanocomposites with high dielectric constant and low loss have been widely used for energy storage applications in power electronics and power delivery systems. However, ...there are still changes in preparing polymer-based dielectric nanocomposites with the suppressed loss (tan δ) and maintain breakdown strength (Eb) through simple compound method. In this work, a simple approach to fabricate outstanding comprehensive performance dielectric composites was proposed by cooperating molybdenum disulfide-polypyrrole (MoS2-PPy) hybrids with polyvinylidene Fluoride (PVDF). The MoS2-PPy hybrids were prepared by in situ polymerization of pyrrole with exfoliated MoS2 nanosheets, showing a “sandwich-like” structure of PPy/MoS2/PPy. MoS2-PPy hybrids significantly influenced the dielectric properties of their composites. As result, PVDF/MoS2-PPy composites achieved high dielectric constant (149.5@1 kHz), suppressed dielectric loss (0.19@1 kHz) and high breakdown strength (250.6 MV m−1). The emphasized reasons of high dielectric property are the enhanced interfacial polarization and formation of nano- and micro-capacitor networks. This work could provide an effective method to design and improve the performance of polymer-based dielectric nanocomposites for power system and energy storage applications.
Gastric cancer remains the third leading cause of cancer-related mortality worldwide, and proliferation of gastric cancer represents the major reason for its poor prognosis. Recent evidence indicates ...that long non-coding RNAs play crucial roles in development and progression of gastric cancer. Long non-coding RNA differentiation antagonizing non-protein coding RNA is upregulated in hepatic cell carcinoma, but the role of lncRNA differentiation antagonizing non-protein coding RNA in gastric cancer has not been explored. In this article, we found that differentiation antagonizing non-protein coding RNA is also upregulated in gastric cancer. Experiments revealed that silencing differentiation antagonizing non-protein coding RNA significantly inhibited gastric cancer cell proliferation in vitro and in vivo. Overexpression of differentiation antagonizing non-protein coding RNA notably increases gastric cancer cell proliferation. From RNA-seq and gene ontology annotations, we found that differentiation antagonizing non-protein coding RNA influences the gene expression programs in cell metabolic and cycle process. Taken together, our findings suggest that the long non-coding RNA differentiation antagonizing non-protein coding RNA promotes the proliferation of gastric cancer and is a potential prognostic biomarker and therapeutic target in gastric cancer.
•The composite PCMs were fabricated through CNCs-assisted dispersion of GNPs in PEG.•The PCMs had balanced encapsulation stability, enthalpy and thermal conductivity.•Good energy conversion ability ...was achieved for the composite PCMs.•An intelligent adaptive thermal management component was successfully designed.
The hybrid networks of cellulose nanocrystals (CNCs) and graphene nanoplatelets (GNPs) were constructed in polyethylene glycol (PEG) through the common solution compounding processing, in which GNPs provided the thermally conductive path while CNCs restricted the leakage of PEG during the phase transition. The results showed that CNCs greatly enhanced the shape stability of the composite phase change materials (PCMs) while thermal conductivity was still maintained at high level. At the contents of 8 wt% (CNCs) and 4 wt% (GNPs), the enthalpy of the composite PCM was 145.5 J/g, which was 88 % of pure PEG, and the thermal conductivity was 2.018±0.067 W/m K about 563.7 % higher than that of pure PEG. Furthermore, the composite PCMs exhibited outstanding light-thermal and electro-thermal conversion capabilities. Furthermore, the composite PCMs could be designed as the temperature stabilizing component exhibiting intelligent adaptive thermal management role, providing stable temperature condition for electronic devices in extreme environment.
A multi-objective and multi-parameter optimization is implemented to design the optimal structure of bismuth-telluride-based TEG (thermoelectric generator) module. A multi-physics TEG model combining ...the SCG (simplified conjugate-gradient) algorithm is used as the optimization tool. The semiconductor pair number, leg length, and base area ratio of semiconductor columns to TEG module significantly affect the TEG performance, and hence are all incorporated into the present optimization study. A single-objective optimization is first implemented to provide input parameters for the multi-objective optimization. The results show that when taking the output power as the single-objective function, the output power can be elevated significantly by optimization of the three geometric parameters but which also accompanies the significant reduction in the conversion efficiency. The same result also occurs when taking the conversion efficiency as the single-objective function. By combining the output power and conversion efficiency with a weight factor as the multi-objective function, the optimization is again implemented. The optimal design obtained by multi-objective optimization makes a proper balance between the output power and conversion efficiency, so that the both are improved simultaneously.
•A multi-physics TEG (thermoelectric generator) model combining a SCG algorithm is used as optimization tool.•The multi-objective optimization is implemented to look for the optimal TEG design.•Three key geometric parameters are chosen as the search variables.•Output power and conversion efficiency are elevated simultaneously by optimization.
Gas gangrene is usually manifested as myonecrosis and subcutaneous gas accumulation, but rarely manifested as arterial occlusion or pneumatosis in the right ventricle and the pulmonary artery. In the ...presence of gas gangrene, special care must be taken to prevent against the formation of circulatory air embolism. The gas gangrene-induced gangrene in the limb of this patient might be attributed to the combined action of infection and arterial occlusion. MDT (Multidisciplinary team)-Green Channel mode is conductive to treatment success of gas gangrene.
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