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Hydrogen sutfide protects colon cancer cells from chemopreventative agent β-phenylethyl isothiocvanate induced apoptosis

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World Journal of Gastroenterology 2005年第26期11卷 3990-3997页

作者： Peter Rose Philip K Moore Shen Han Ming Ong Choon Nam Jeffrey S Armstrong Matt Whiteman department of Biochemistry National University of Singapore 8 Medical Drive117597Singapore department of Pharmacology National University of Singapore 18 Medical Drive117597 Singapore department of Community Occupational and Family Medicine National University of Singapore 16 Medical Drive 117597 Singapore

AIM:Hydrogen sulfide (H2S) is a prominent gaseous constituent of the gastrointestinal (GI) tract with known cytotoxic properties. Endogenous concentrations of H2S are reported to range between 0.2-3.4 mmol/L in the GI tract of mice and humans. Considering such high levels we speculate that, at non-toxic concentrations, H2S may interact with chemical agents and alter the response of colonic epithelium cells to such compounds. The GI tract is a major site for the absorption of phytochemical constituents such as isothiocyanates, flavonoids, and carotenoids, with each group having a role in the prevention of human diseases such as colon cancer. The chemopreventative properties of the phytochemical agent p-phenyethyl isothiocyanate (PEITC) are well recognized. However, little is currently known about the physiological or biochemical factors present in the GI tract that may influence the biological properties of ITCs. The current study was undertaken to determine the effects of H2S on PEITC mediated apoptosis in colon cancer cells. METHODS: Induction of apoptosis by PEITC in human colon cancer HCT116 cells was assessed using classic apoptotic markers namely SubGl population analysis, caspase-3 like activity and nuclear fragmentation and condensation coupled with the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrasodium bromide) viability assay and LDH leakage. RESULTS: PEITC significantly induced apoptosis in HCT116 cells as assessed by SubGl population formation, nuclear condensation, LDH leakage and caspase-3 activity after 24 h, these data being significant from control groups (P<0.01). In contrast, co-treatment of cells with physiological concentrations of H2S (0.1-1 mmol/L) prevented PEITC mediated apoptosis as assessed using the parameters described. CONCLUSION: PEITC effectively induced cell death in the human adenocarcinoma cell line HCT116 in vitro through classic apoptotic mechanisms. However, in the presence of H2S, apoptosis was abolished. These data sugg

关键词： Apoptosis Colon cancer Hydrogen sulfide β-phenylethyl isothiocyanate

Review of post-combustion carbon dioxide capture technologies using activated carbon

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Journal of Environmental Sciences 2019年第9期31卷 46-63页

作者： Alivia Mukherjee Jude A.Okolie Amira Abdelrasoul Catherine Niu Ajay K.Dalai department of Chemical and Biological Engineering University of Saskatchewan Saskatoon 57 Campus Drive

Carbon dioxide(CO2) is the largest anthropogenic greenhouse gas(GHG) on the planet contributing to the global warming. Currently, there are three capture technologies of trapping CO2 from the flue gas and they are pre-combustion, post-combustion and oxy-fuel combustion. Among these, the post-combustion is widely popular as it can be retrofitted for a short to medium term without encountering any significant technology risks or *** carbon is widely used as a universal separation medium with series of advantages compared to the first generation capture processes based on amine-based scrubbing which are inherently energy intensive. The goal of this review is to elucidate the three CO2 capture technologies with a focus on the use of activated carbon(AC) as an adsorbent for post-combustion anthropogenic CO2 flue gas capture prior to emission to atmosphere. Furthermore, this coherent review summarizes the recent ongoing research on the preparation of activated carbon from various sources to provide a profound understanding on the current progress to highlight the challenges of the CO2 mitigation efforts along with the mathematical modeling of CO2 capture. AC is widely seen as a universal adsorbent due to its unique properties such as high surface area and porous texture. Other applications of AC in the removal of contaminants from flue gas, heavy metal and organic compounds, as a catalyst and catalyst support and in the electronics and electroplating industry are also discussed in this study.

关键词： Post-combustion Greenhouse gas Carbon dioxide capture Activated carbon Adsorption

A Focused Laser Beam:A Useful and Versatile Tool for 1D Nanomaterials Research:A Review

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Journal of Materials Science & Technology 2015年第6期31卷 616-629页

作者： Junpeng Lu Sharon Xiaodai Lim Chorng Haur Sow department of Physics National University of Singapore department of Science drive National University of Singapore National University of Singapore

One-dimensional(1D) nanomaterials have generated considerable interest amongst researchers because of their potential as fundamental building block in future nano- and micro-electronic *** this article,we present a review of a focused laser beam system as a versatile tool for the manipulation,structural transformation,micropatterning and chemical modification of 1D *** tool was found to be effective in patterning and modifying various physical and chemical properties of the pristine1 D *** also aids in the fabrication process of heterostructures and 1D nanomaterial based ***,we present the implementation of the focused laser beam setup as a valuable tool in the study of the origins and photoresponse mechanism of the 1D nanomaterial devices.

关键词： Laser Nanomaterials Composite Optoelectronic Elect

ROBOD, room-level occupancy and building operation dataset

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Building Simulation 2022年第12期15卷 2127-2137页

作者： Zeynep Duygu Tekler Eikichi Ono Yuzhen Peng Sicheng Zhan Bertrand Lasternas Adrian Chong department of the Built Environment National University of Singapore4 Architecture Drive117566Singapore

The availability of the building’s operation data and occupancy information has been crucial to support the evaluation of existing models and development of new data-driven *** paper describes a comprehensive dataset consisting of indoor environmental conditions,Wi-Fi connected devices,energy consumption of end uses(i.e.,HVAC,lighting,plug loads and fans),HVAC operations,and outdoor weather conditions collected through various heterogeneous sensors together with the ground truth occupant presence and count information for five rooms located in a university *** five rooms include two different-sized lecture rooms,an office space for administrative staff,an office space for researchers,and a library space accessible to all students.A total of 181 days of data was collected from all five rooms at a sampling resolution of 5 *** dataset can be used for benchmarking and supporting data-driven approaches in the field of occupancy prediction and occupant behaviour modelling,building simulation and control,energy forecasting and various building analytics.

关键词： building operation data occupancy data sensor fusion occupancy prediction building simulation and control

SN 2009ip and SN 2010mc as dual-shock Quark-Novae

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Research in Astronomy and Astrophysics 2013年第12期13卷 1463-1470页

作者： Rachid Ouyed Nico Koning Denis Leahy department of Physics and Astronomy University of Calgary 2500 University Drive NW

In recent years a number of double-humped supernovae （SNe） have been discovered. This is a feature predicted by the dual-shock Quark-Nova （QN） model where an SN explosion is followed （a few days to a few weeks later） by a QN explo- sion. SN 2009ip and SN 2010mc are the best observed examples of double-humped SNe. Here, we show that the dual-shock QN model naturally explains their light curves including the late time emission, which we attribute to the interaction between the mixed SN and QN ejecta and the surrounding circumstellar matter. Our model applies to any star （O-stars, luminous blue variables, Wolf-Rayet stars, etc.） provided that the mass involved in the SN explosion is ~ 20 Mo which provides good conditions for forming a QN.

关键词： circumstellar matter -- stars: evolution -- stars: winds outflows --supernovae: general -- supernovae: individual (SN 2009ip SN 2010mc)

Substitutional doping in 2D transition metal dichalcogenides

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Nano Research 2021年第6期14卷 1668-1681页

作者： Leyi Loh Zhepeng Zhang Michel Bosman Goki Eda department of Physics National University of Singapore2 Science Drive 3Singapore117551Singapore department of Materials Science and Engineering National University of Singapore9 Engineering Drive 1Singapore117575Singapore department of Chemistry National University of Singapore3 Science Drive 3Singapore117543Singapore Centre for Advanced 2D Materials National University of Singapore2 Science Drive 2Singapore117542Singapore

Two-dimensional(2D)van der Waals transition metal dichalcogenides(TMDs)are a new class of electronic materials offering tremendous opportunities for advanced technologies and fundamental *** to conventional semiconductors,substitutional doping is key to tailoring their electronic properties and enabling their device ***,we review recent progress in doping methods and understanding of doping effects in group 6 TMDs(MX2,M=Mo,W;X=S,Se,Te),which are the most widely studied model 2D semiconductor *** and theoretical studies have shown that a number of different elements can substitute either M or X atoms in these materials and act as n-or p-type *** review will survey the impact of substitutional doping on the electrical and optical properties of these materials,discuss open questions,and provide an outlook for further studies.

关键词： substitutional doping transition metal dichalcogenide two-dimensional semiconductor acceptor donor

Exciton dissociation dynamics and light-driven H2 generation in colloidal 2D cadmium chalcogenide nanoplatelet heterostructures

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Nano Research 2018年第6期11卷 3031-3049页

作者： Qiuyang Li Tianquan Lian department of Chemistry Emory University 1515 Dickey Drive NE Atlanta GA 30322 USA

Solar-to-H2 conversion is attracting much research attention as a potential approach to meet global renewable energy demands. Although significant advances have been made using metal-tipped colloidal cadmium chalcogenide zero-dimensional （0D） quantum dots and one-dimensional （1D） nanorod heterostructures in solar-to-H2 conversion, their efficiency may be further enhanced using an emerging class of colloidal cadmium chalcogenide nanocrystals, namely two-dimensional （2D） nanoplatelets （NPLs）, because of their unique properties. In this review, we summarize the recent advances on exciton dissociation dynamics and light-driven H2 generation performance of colloidal nanoplatelet heterostructures. Following an introduction on the electronic structure of 2D NPLs, we discuss the dynamics of exciton dissociation by electron transfer to molecular acceptors. The exciton quenching dynamics of CdS NPL-Pt and CdSe NPL-Pt heterostructures are compared to highlight the effect of material properties on the relative contributions of the energy-transfer and electron- transfer pathways. Representative solar-to-H2 conversion performances of 2D NPL-metal heterostructures are discussed and compared with those of 1D nanorod-metal heterostructures. Finally, we discuss the challenges in further improving the solar-to-fuel conversion efficiencies of these systems.

关键词： colloidal nanoplatelets semiconductor-metal heterostructures exciton dissociation electron transfer hydrogen generation

Visualizing Photodynamic Therapy in Transgenic Zebrafish Using Organic Nanoparticles with Aggregation-Induced Emission

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Nano-Micro Letters 2018年第4期10卷 61-69页

作者： Purnima Naresh Manghnani Wenbo Wu Shidang Xu Fang Hu Cathleen Teh Bin Liu department of Chemical and Biomolecular Engineering National University of Singapore 4 Engineering Drive 4 Institute of Molecular and Cell Biology Proteos BuildingBiopolis Drive

Photodynamic therapy(PDT) employs accumulation of photosensitizers(PSs) in malignant tumor tissue followed by the light-induced generation of cytotoxic reactive oxygen species to kill the tumor cells. The success of PDT depends on optimal PS dosage that is matched with the ideal power of light. This in turn depends on PS accumulation in target tissue and light administration time and *** theranostic nanomedicine is driven by multifunctional therapeutics that aim to achieve targeted tissue delivery and image-guided therapy, fluorescent PS nanoparticle(NP)accumulation in target tissues can be ascertained through fluorescence imaging to optimize the light dose and administration parameters. In this regard, zebrafish larvae provide a unique transparent in vivo platform to monitor fluorescent PS bio-distribution and their therapeutic efficiency. Using fluorescent PS NPs with unique aggregation-induced emission characteristics, we demonstrate for the first time the real-time visualization of polymeric NP accumulation in tumor tissue and, more importantly, the best time to conduct PDT using transgenic zebrafish larvae with inducible liver hyperplasia as an example.

关键词： Nanomedicine Photodynamic therapy Transgenic zebrafish Aggregation-induced emission Organic nanoparticles

Magneto-plasticity in micro-cutting of single-crystal copper

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Journal of Materials Science & Technology 2022年第29期124卷 121-134页

作者： Yunfa Guo YanJin Lee Yu Zhang Hao Wang department of Mechanical Engineering National University of Singapore9 Engineering Drive 1Singapore 117575Singapore

The plasticity of metals can be significantly affected by the application of a magnetic field,otherwise known as the magneto-plastic *** paper investigates the magneto-plastic effect in the microcutting of a non-magnetic ductile material,single-crystal copper,under a weak magnetic field and reports the influence of the phenomenon on the cutting forces and machined surface quality.A softening effect was observed from the large reduction in cutting forces from 3.2 N to 1.5 N under the magnetic *** compared to the magnetic field intensity and polarity,the variation in magnetic field orientations with respect to the cutting direction exhibited a stronger influence on the cutting force,chip morphology,machined surface texture,subsurface microstructure,surface roughness,and machined surface microhardness of the copper *** analytical model was developed based on the geometry of the cutting chips to correlate the orientation-dependent influence of the magnetic field on the cutting *** the surface quality,excessive folds with four different types of morphology produced under magnetic-free cutting were suppressed after applying the magnetic field with the most significant improvement achieved with the 90°magnetic field *** magnetic-assisted changes in machined surface morphology also led to the reduction in machined surface roughness and *** optimistic micro-cutting outcomes in this work establish a greater understanding of the magneto-plastic effect and demonstrate the applicability of magneto-plasticity in ultraprecision manufacturing.

关键词： Micro-cutting Magnetic field Plasticity Mechanical response Anisotropy