Described herein is the first intermolecular σ‐bond exchange reaction between the C−C bond of cyclopropenones and C−Si bond of (benzo)silacyclobutanes and it proceeds smoothly by treatment with ...either 1 mol % of a palladium or 2 mol % of a nickel catalyst. This reaction constitutes an unprecedented route for the synthesis of various sila(benzo)suberones. And it is also the first example of a σ‐bond exchange reaction involving cyclopropenones.
The exchange: Described is the first intermolecular σ‐bond cross‐exchange reaction between the C−C bond of cyclopropenones and the C−Si bond of (benzo)silacyclobutanes. The reaction constitutes the first catalytic method for the synthesis of a variety of sila(benzo)suberones. cod=1,5‐cyclooctadiene.
•A comprehensive numerical study on the subcooled falling film heat transfer on a horizontal smooth tube is conducted.•The role of surface tension in the calculation of falling film heat transfer is ...discussed.•A heat transfer correlation considering a multitude of factors is developed.
The effects of film flow rate, heat flux, inlet liquid temperature, tube diameter and liquid distributor height on subcooled falling film heat transfer outside a horizontal smooth tube are numerically studied, and a heat transfer correlation based on the current data is developed. Comparisons between the predicted results and the published experimental data in the literature are also conducted. The calculation ranges are: film flow rate from 0.025 to 0.284 kg m−1 s−1, heat flux from 1.0 to 100 kW m−2, inlet liquid temperature from 2 to 104 °C, tube diameter from 6.35 to 50.8 mm and liquid distributor height from 3.0 to 50.8 mm. The results indicate that: (1) the numerical results of the local heat transfer coefficient are in good agreement with the experimental data in the literature; (2) the surface tension plays an important role in the calculations of heat transfer in two stagnation zones, (3) the heat transfer coefficient shows four distinct zones along with peripheral angle: stagnation zone, impingement zone, thermal layer development zone and departure zone; (4) the heat transfer coefficient increases with increase in film flow rate, tube diameter or liquid distributor height, while keeps constant with increasing heat flux; (5) the correlation predicts 92% of the total 141 calculated data with deviations within ±10%, and predicts 78% of 284 data available in literature with deviations within ±30%.
•The effects of tube diameter, saturation temperature, film flow rate and heat flux on heat transfer are studied.•A threshold Reynolds number is proposed to delineate the test data into full wetting ...and partial dryout regimes.•The heat transfer correlations for R134a outside a single horizontal tube are developed.•Comparisons between the predicated results and the experimental data of other refrigerants in literature are conducted.
For the full wetting regime of falling film evaporation on a single horizontal smooth tube, the proposed correlation fits 94% of the data within ±20%.
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The falling film heat transfer of R134a outside a single horizontal smooth tube is experimentally investigated, and the effects of the tube diameter, saturation temperature, film flow rate and heat flux are studied. A threshold Reynolds number is proposed to delineate the test data into full wetting and partial dryout regimes. New correlations based on the present data and some data in literature are fitted for both regimes. The correlation for partial dryout regime fits 91% of the 153 data within ±20%, and the correlation for full wetting regime fits 94% of the 205 data within ±20%. The correlations have also been compared with previous measured data of other refrigerants available in literature. It is found that the predictions for partial dryout regime agree with most of the previous data with a deviation of ±30%.
•Falling film evaporation heat transfer of R134a, R290 and R600a is characterized.•Heat transfer correlations for five refrigerants are suggested in two regimes.•Proposed correlations predict the ...base data and data from references reasonably.
Falling film evaporation heat transfer of R134a and its potential substitutes R290 and R600a outside a single horizontal plain tube is experimentally investigated, and the effects of the saturation temperature, film flow rate and heat flux on heat transfer coefficient are studied. Heat transfer performance of R290 is slightly superior than that of R134a, while R600a is inferior than that of R134a. The threshold film Reynolds number is determined to separate the variation trend of HTC with film Reynolds number into full wetting and partial dryout regimes. Increase of heat flux benefits the heat transfer in both full-wetting and partial dry-out regimes. New heat transfer correlations based on the present data and data for R32 and R1234ze(E) in the authors’ group are suggested for two regimes. The correlation for full wetting regime fits 96.7% of the total 542 correlated data within ±30% while fits 73.4% of the total 289 data in references from −30% to +15%, the correlation for partial dryout regime fits 97.5% of the total 162 correlated data within ±30% while fits 76.8% of the total 95 data from references within ±30%.
•Computational methods for falling film flow and heat transfer were summarized.•Falling film flow and heat transfer on 2D and 3D perspectives were reviewed.•Film thickness and heat transfer ...prediction on the horizontal tubes were concerned.•Some recommendations and improvements for future research were proposed.
Falling film evaporation is a promising technology widely applied in refrigeration, desalination and beyond applications owing to the great advantages. However, the liquid film hydrodynamics and heat transfer performance are studied insufficiently. Compered with experiments, numerical simulations are economical and efficient especially in the study of liquid film, through which some microscopic understandings are expected to be extracted. In this paper, a comprehensive review for a large pool of computational studies about falling liquid film flow and heat transfer on the horizontal tube and tube bundle is presented. Computational methods of liquid–gas two-phase flow and mass transfer model, as well as relevant researches were first introduced. Then, the studies on the falling film hydrodynamics, film thickness, sensible heat transfer, flow pattern, evaporation and boiling outside the single tube, tube bundle, special-shaped tube and entire evaporator studied with 2D and 3D models are respectively reviewed in order. Then, the investigations on the falling film breakout and dryout are reviewed. And then, the numerical predictions of falling film thickness and heat transfer coefficient are involved. Afterthat, the benchmark data for falling film numerical simulation are summarized. Finally, some future needs and recommendation relating to crucial technologies that must be solved are proposed.
Background
Molecular subtyping of triple‐negative breast cancers (TNBCs) via gene expression profiling is essential for understanding the molecular essence of this heterogeneous disease and for ...guiding individualized treatment. We aim to devise a clinically practical method based on immunohistochemistry (IHC) for the molecular subtyping of TNBCs.
Materials and Methods
By analyzing the RNA sequencing data on TNBCs from Fudan University Shanghai Cancer Center (FUSCC) (n = 360) and The Cancer Genome Atlas data set (n = 158), we determined markers that can identify specific molecular subtypes. We performed immunohistochemical staining on tumor sections of 210 TNBCs from FUSCC, established an IHC‐based classifier, and applied it to another two cohorts (n = 183 and 214).
Results
We selected androgen receptor (AR), CD8, FOXC1, and DCLK1 as immunohistochemical markers and classified TNBCs into five subtypes based on the staining results: (a) IHC‐based luminal androgen receptor (IHC‐LAR; AR‐positive +), (b) IHC‐based immunomodulatory (IHC‐IM; AR‐negative −, CD8+), (c) IHC‐based basal‐like immune‐suppressed (IHC‐BLIS; AR−, CD8−, FOXC1+), (d) IHC‐based mesenchymal (IHC‐MES; AR−, CD8−, FOXC1−, DCLK1+), and (e) IHC‐based unclassifiable (AR−, CD8−, FOXC1−, DCLK1−). The κ statistic indicated substantial agreement between the IHC‐based classification and mRNA‐based classification. Multivariate survival analysis suggested that our IHC‐based classification was an independent prognostic factor for relapse‐free survival. Transcriptomic data and pathological observations implied potential treatment strategies for different subtypes. The IHC‐LAR subtype showed relative activation of HER2 pathway. The IHC‐IM subtype tended to exhibit an immune‐inflamed phenotype characterized by the infiltration of CD8+ T cells into tumor parenchyma. The IHC‐BLIS subtype showed high expression of a VEGF signature. The IHC‐MES subtype displayed activation of JAK/STAT3 signaling pathway.
Conclusion
We developed an IHC‐based approach to classify TNBCs into molecular subtypes. This IHC‐based classification can provide additional information for prognostic evaluation. It allows for subgrouping of TNBC patients in clinical trials and evaluating the efficacy of targeted therapies within certain subtypes.
Implications for Practice
An immunohistochemistry (IHC)‐based classification approach was developed for triple‐negative breast cancer (TNBC), which exhibited substantial agreement with the mRNA expression‐based classification. This IHC‐based classification (a) allows for subgrouping of TNBC patients in large clinical trials and evaluating the efficacy of targeted therapies within certain subtypes, (b) will contribute to the practical application of subtype‐specific treatment for patients with TNBC, and (c) can provide additional information beyond traditional prognostic factors in relapse prediction.
This article describes an immunohistochemistry‐based approach to classification of triple‐negative breast cancers into molecular subtypes for purposes of the translation of TNBC molecular classification into clinical practice.
Deep learning, e.g., convolutional neural networks (CNNs), has achieved great success in image processing and computer vision especially in high-level vision applications, such as recognition and ...understanding. However, it is rarely used to solve low-level vision problems such as image compression studied in this paper. Here, we move forward a step and propose a novel compression framework based on CNNs. To achieve high-quality image compression at low bit rates, two CNNs are seamlessly integrated into an end-to-end compression framework. The first CNN, named compact convolutional neural network (ComCNN), learns an optimal compact representation from an input image, which preserves the structural information and is then encoded using an image codec (e.g., JPEG, JPEG2000, or BPG). The second CNN, named reconstruction convolutional neural network (RecCNN), is used to reconstruct the decoded image with high quality in the decoding end. To make two CNNs effectively collaborate, we develop a unified end-to-end learning algorithm to simultaneously learn ComCNN and RecCNN, which facilitates the accurate reconstruction of the decoded image using RecCNN. Such a design also makes the proposed compression framework compatible with existing image coding standards. Experimental results validate that the proposed compression framework greatly outperforms several compression frameworks that use existing image coding standards with the state-of-the-art deblocking or denoising post-processing methods.
Falling film heat and mass transfer, representatives of advanced and low-carbon heat and mass transfer technologies, has been applied in a variety of thermal processes due to its great prospect for ...heat and mass transfer enhancement. However, the hydrodynamics, heat and mass transfer are significantly influenced by the gas (vapor or air) streams during the operation of falling film heat exchangers. To acquire the detailed profiles of flow, temperature and concentration and to explore the influence mechanism of gas stream shearing on the falling film hydrodynamics and heat and mass transfer, researchers have adopted experimental, analytical and numerical methods for different attempts. This paper presents a comprehensive summarization of the relevant work concerning the hydrodynamic, heat and mass transfer characteristics of falling film components, including the evaporator, absorber, evaporative cooler and dehumidifier. Considering the specific applications, the cocurrent, countercurrent, and cross gas streams shearing on the liquid film on a horizontal tube and bundle, a vertical tube and a vertical plate are reviewed. The objective of this review is to cover sufficient knowledge of the results, findings and insights of gas stream impacts on the hydrodynamics, heat and mass transfer in building utilized heat exchangers to provide guidance on how to maximize the positive effect or at least minimize the negative impact of gas shearing on the falling film heat and mass transfer.
Schematics of gas stream models encountered in various applications. Display omitted
•Provide the first review of the gas stream effect on falling liquid film flow.•Clarified mechanisms of gas effect on liquid film flow, heat and mass transfer.•Summarized studies of gas stream effect on falling film flow, heat and mass transfer.•Concerned film thickness, heat and mass transfer prediction under gas shearing.•Proposed some recommendations and improvements for future research.
•Falling film evaporation heat transfer coefficients was augmented by a factor of 2.1–4.9.•The pool boiling yielded a higher heat transfer coefficient at higher heat flux for enhanced tube.•Pool ...boiling and falling film evaporation were both dominated by the phase change heat transfer.
Falling film evaporation and pool boiling of R134a outside a typical reentrant enhanced tube was investigated with an experimental approach. Experimental data from literature with other refrigerants were also compared. The saturation temperature was 11 °C. It was found that the overall heat transfer coefficient for the enhanced tube was as much as 3 times higher than smooth tube. Shell-side falling film evaporation heat transfer coefficient increased by a factor of 2.1–4.9. Pool boiling yielded a higher heat transfer coefficient at higher heat flux for the same enhanced tube. The dependence of falling film evaporation heat transfer coefficient on the heat flux was also different from pool boiling for the same tube. Although the bubbles in pool boiling were pushed up by buoyancy and in falling film evaporating were driven by the flow of films, the transmission of energy were both dominated by the phase change heat transfer. The contribution of forced convection to falling film evaporation heat transfer coefficient is weak compared with phase change heat transfer.
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