115 research outputs found
Effect of Thionation of the Carbonyl Groups in Naphthalimide‐Phenoxazine Electron Donor–Acceptor Dyads on the Excited‐ State Dynamics: Transient Optical and Electron Paramagnetic Resonance Spectral Studies
No full text: We performed thionation of the electron acceptor naphthalimide (NI) moiety in donor-acceptor (D-A) dyads in a series of thio-substituted D-A dyads. Thionation significantly enhances the electron-accepting ability of the chromophore, facilitating the formation of low-lying charge-separated (CS) states. Femtosecond transient absorption spectra revealed intersystem crossing (ISC) rate constants of S-NI-PXZ (kISC = 3.8 E11 s-1) and DS-NI-PXZ (kISC = 2.4 E11 s-1), which are interestingly independent of the number of sulfur atoms. Generally, fluorescence quenching was observed due to the rapid ISC process. Native NI-PXZ exhibits thermally activated delayed fluorescence (TADF). Thionation increased the singlet-triplet energy gap, making the TADF vanish. In n-hexane, nanosecond transient absorption spectroscopy detected the triplet lifetimes shortened from 11.6 μs of NI-PXZ to 0.66 μs for S-NI-PXZ and 0.25 μs for DS-NI-PXZ. Time-resolved electron paramagnetic resonance revealed the large zero-field splitting D value (4200-9800 MHz) of the triplet state of the thionated derivatives, which is due to the much larger SOC matrix elements of triplet state of DS-NI-PXZ (ca. 135 cm-1) and DS-NI (ca. 136 cm-1) than the nonthionated NI (3.1 cm-1). Thionation of the carbonyl groups in chromophore is a promising method for design of triplet photosensitizers to achieve fast ISC
A study on the hydration of calcium aluminate cement pastes containing silica fume using non-contact electrical resistivity measurement
No full textIn this study, a non-contact electrical resistivity method is employed to investigate the hydration process of calcium aluminate cement (CAC) pastes incorporating silica fume (SF) at an early age. The CAC-SF pastes have a water-to-binder ratio (w/b) of 0.6 and a replacement of SF for CAC at 0, 5, 10, and 20% (by weight of the binder). The pastes are tested for electrical resistivity, thermal analysis (internal temperature), setting time, and compressive strength, and the hydration products of the pastes are also examined. The results indicate that the evolution of electrical resistivity is closely related to the hydration process of the CAC pastes, and the conversion stage is closely associated with the setting time of pastes. As the increase of SF replacement, the hydration process of CAC pastes was accelerated within 24 h, and the development of compressive strength was hampered at an early age but increased later. SF replacement inhibits the conversion of metastable CAC hydrates (CAH10 and C2AH8) to C3AH6 through filling, seeding, and reacting with CAC, thus reducing the heat of hydration.This article is published as Liao, Yishun, Sichun Wang, Kejin Wang, Siraj Al Qunaynah, Shihui Wan, Zhengxia Yuan, Pengfei Xu, and Shengwen Tang. "A study on the hydration of calcium aluminate cement pastes containing silica fume using non-contact electrical resistivity measurement." Journal of Materials Research and Technology 24 (2023): 8135-8149.
DOI: 10.1016/j.jmrt.2023.05.080.
Copyright 2023 The Authors.
Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0).
Posted with permission
Early hydration and mechanical properties of high-belite sulfoaluminate cement blended with ferrite
No full textIn this study, the effect of ferrite incorporation on the hydration of high-belite sulfoaluminate cement was investigated. The fluidity, compressive strength, heat of hydration, electrical resistivity, and scanning electron microscopy-energy dispersive X-ray spectroscopy results of the cement paste were evaluated. The results indicate that the incorporation of ferrite promoted the early hydration rate of the cement and accelerated the formation of calcite. It also promoted the generation of strätlingite and accelerated the reaction of belite during the late hydration stage. With an increase in the ferrite content, the exothermic capacity of the cement gradually decreased. The early hydration products of ferrite in cement pastes have multidirectional crystals (ettringite) and gels (calcium silicate hydrate). The Fe element was found to alter the structure of ettringite, resulting in an antler-like shape. Furthermore, according to the EDS results, ettringite contained more Fe, indicating that Fe migration was inclined toward the crystals. Thermodynamic modeling demonstrated that the growth of ettringite and strätlingite in the paste was promoted, which was consistent with the experimental results.This is a manuscript of an article published as Hu, Mengting, Yishun Liao, Zhonghui Cai, Caisheng Meng, Shihui Wan, Shengwen Tang, Siraj Al Qunaynah, and Kejin Wang. "Early hydration and mechanical properties of high-belite sulfoaluminate cement blended with ferrite." Construction and Building Materials 489 (2025): 142138. doi: https://doi.org/10.1016/j.conbuildmat.2025.142138
Double dissociation of neural responses supporting perceptual and cognitive components of social cognition: Evidence from processing of others' pain
No full textModels on how perceptual and cognitive information on others' mental states are treated by the cognitive architecture are often framed as duplex models considering two independent systems. In the context of the neuroscience of empathy analogous systems have been described. Using event-related potentials (i.e., ERPs) technique, we tested the hypothesis of temporal dissociation of two functional systems. We implemented a design in which perceptual (i.e., painful or neutral facial expressions) and contextual (i.e., painful or neutral related sentences) cues on others' mental states were orthogonally manipulated. Painful expressions selectively modulated the early activity at 110–360 ms over fronto-central and centro-parietal regions, whereas painful contexts selectively modulated the late activity at 400–840 ms over these same regions. Notably, the reactions to pain triggered by these cues added up when both were available, that is the joint reaction was characterized by additive effects. These findings favor a model assuming distinct neural paths of perceptual and cognitive processing, at least when the cognitive component is triggered by language
Evaluation of HIFU-induced lesion region using temperature threshold and equivalent thermal dose methods
No full textEffect of alignment angle on the alignment accuracy of a miniature rotation robot for microscopy imaging
No full textMost recently, a miniature rotation robot has been proposed to allow imaging samples from multidirection for the first time. However, one existing problem for that rotation robot is that the alignment efficiency and accuracy is affected greatly by the alignment angle. This article investigates the effect of alignment angle on the alignment accuracy. Alignment accuracy is measured by sample’s position shift during a 360° rotation. Firstly, the miniature robotic system and its alignment principle are introduced briefly. Then, the source of alignment error is analyzed and the error model is built. After that, simulation results are given and indicate that as alignment angle increases, alignment error first decreases, then becomes stable and finally increases. Reasons for the trend of alignment error are explained. Finally, experiment results are demonstrated and have a good agreement with theoretical analysis and simulation results. The results indicate that 90° should be chosen as the alignment angle to ensure both alignment accuracy and alignment speed
Yi wang zhi mei: ji yi yu xiang xiang de yi jing
No full textM.F.A.Since the history of the human race, human brain has long been examined and studied in order to answer the questions of memory. Memory becomes the major research topic in different discipline including philosophy, art and literature. What exactly memory stands for while we subconsciously recall our memories? This thesis starts with the question of what is memory and in the process of understanding memory puts forward the importance of imagination. At the same time, the thesis discusses how art presents the vision of memory and imagination in the contemporary context. I explore the relationship between memory and imagination through integrating western theory on memory space. From the process of memory, this thesis explore the external space and internal space of multiple structures of memory space, and indicate the relationship between memory and time. By studying Chinese and Western researches on ruins, explore how ruins, as a metaphor, become a carrier of memory to represent memory and history. Last but not least, I would like to draw an analogy between forgetting and incompleteness as to suggest the value of obliteration and inscription based on the research of the oriental aesthetics. Lastly, I will fully examine my own artistic practices with my reflections on ruins.First of all, the thesis is going to discuss the 3 types of memory space both internally and externally in order to emphasise the relationship between memory and space. Secondly, I put forward my concern about how ruins become a metaphorical carries of memory. Thirdly, I will talk about the aesthetic value of forgetting and incompleteness in the ground of oriental philosophical spirit. The last part of the thesis would be my personal artistic creations reflecting my interpretation on memory and imagination.長久以來，人類致力於研究大腦，渴望解答關於記憶的問題。記憶成為了多個界別的研究對象，不論哲學、藝術、文學等範疇。然而，當我們下意識地說起自身的回憶的時候，有沒有想過記憶到底是什麼？本文透過什麼是記憶的提問展開，在理解記憶的過程中，提出想像的重要性。與此同時，討論在當代的語境下，藝術如何呈現記憶與想像的意境。透過綜合西方理論對記憶空間的論述，探討記憶與想像之間的關係。從記憶的過程，探討記憶多重結構的外在空間及內在空間。整合及引用中西方對廢墟的研究，探討其作為隱喻，如何成為記憶的載體述說記憶與歷史。以東方美學精神的研究為基礎，說明殘缺與遺忘的關係，帶出塗抹與消除的價值與重要性，從而說明藝術美學的意境。最後，引用個人藝術創作思考廢墟與自身的關係。本論文分為四個部分，第一部分將探討三種記憶空間，物理學的記憶部分不在本論文的討論範圍，因此只會說明記憶與空間的關係。第二部分探討記憶與廢墟之間的關係，說明廢墟如何成為記憶的隱喻。第三部分探討遺忘與殘缺的類比關係，以東方美學精神提出塗抹與消除的美學價值。最後一部分探討個人創作的過程及作品主題，如何呈現記憶與想像的意境。黃詩慧."2020年8月".Thesis M.F.A. Chinese University of Hong Kong 2020.Includes bibliographical references (leaves 56-59).Abstract also in English.Title from PDF title page (viewed on March 14, 2022).Huang Shihui
Is the self always better than a friend? Self-face recognition in Christians and atheists.
No full textEarly behavioral studies found that human adults responded faster to their own faces than faces of familiar others or strangers, a finding referred to as self-face advantage. Recent research suggests that the self-face advantage is mediated by implicit positive association with the self and is influenced by sociocultural experience. The current study investigated whether and how Christian belief and practice affect the processing of self-face in a Chinese population. Christian and Atheist participants were recruited for an implicit association test (IAT) in Experiment 1 and a face-owner identification task in Experiment 2. Experiment 1 found that atheists responded faster to self-face when it shared the same response key with positive compared to negative trait adjectives. This IAT effect, however, was significantly reduced in Christians. Experiment 2 found that atheists responded faster to self-face compared to a friend's face, but this self-face advantage was significantly reduced in Christians. Hierarchical regression analyses further showed that the IAT effect positively predicted self-face advantage in atheists but not in Christians. Our findings suggest that Christian belief and practice may weaken implicit positive association with the self and thus decrease the advantage of the self over a friend during face recognition in the believers
How to Identify Mechanisms of Cultural Influences on Human Brain Functions
No full textPsychology, MultidisciplinarySSCI0EDITORIAL MATERIAL137-412
How UV photolysis accelerates the biodegradation and mineralization of sulfadiazine (SD)
No full textabstract: Sulfadiazine (SD), one of broad-spectrum antibiotics, exhibits limited biodegradation in wastewater treatment due to its chemical structure, which requires initial mono-oxygenation reactions to initiate its biodegradation. Intimately coupling UV photolysis with biodegradation, realized with the internal loop photobiodegradation reactor, accelerated SD biodegradation and mineralization by 35 and 71 %, respectively. The main organic products from photolysis were 2-aminopyrimidine (2-AP), p-aminobenzenesulfonic acid (ABS), and aniline (An), and an SD-photolysis pathway could be identified using C, N, and S balances. Adding An or ABS (but not 2-AP) into the SD solution during biodegradation experiments (no UV photolysis) gave SD removal and mineralization rates similar to intimately coupled photolysis and biodegradation. An SD biodegradation pathway, based on a diverse set of the experimental results, explains how the mineralization of ABS and An (but not 2-AP) provided internal electron carriers that accelerated the initial mono-oxygenation reactions of SD biodegradation. Thus, multiple lines of evidence support that the mechanism by which intimately coupled photolysis and biodegradation accelerated SD removal and mineralization was through producing co-substrates whose oxidation produced electron equivalents that stimulated the initial mono-oxygenation reactions for SD biodegradation.This is the authors' final accepted manuscript. The final publication is available at http://dx.doi.org/10.1007/s10532-014-9711-
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