272 results on '"L., Roy"'
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2. Porphyrin‐Based Metal–Organic Frameworks for Neuromorphic Electronics
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Guanglong Ding, Su-Ting Han, Chi-Ching Kuo, Vellaisamy A. L. Roy, and Ye Zhou
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artificial synapses ,data storage ,film preparations ,metal–organic frameworks ,transistors ,Physics ,QC1-999 ,Chemistry ,QD1-999 - Abstract
Porphyrin‐based metal–organic frameworks (PP‐MOFs) have some special features beyond ordinary MOFs, including superior optoelectronic characteristics, the ability to form 2D layered structure, and customizability, which prompt the increasing attention of PP‐MOFs in the field of neuromorphic electronics. The related application research is in the initial stage, and a timely summary and guidance are necessary. The PP‐MOFs fabrication should be shifted from powder synthesis in a chemistry laboratory to high‐quality film preparation under a clean environment to ensure device performance. This article highlights the PP‐MOFs film preparation methods and the application advances in neuromorphic electronics, performs comparative analysis in detail, and puts forward the challenges and future research directions, with the aim to attract the attention of experts in various areas (e.g., chemists, materials scientists, and engineers) and promote the application of PP‐MOFs in neuromorphic electronics.
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- 2023
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3. Recent progress in the design of photocatalytic H2O2 synthesis system
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Haobing Wen, Sen Huang, Xianguang Meng, Xiaole Xian, Jingjing Zhao, and Vellaisamy A. L. Roy
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photocatalysis ,oxygen reduction reaction ,H2O2 synthesis ,cocatalyst ,surface modification ,ion doping ,Chemistry ,QD1-999 - Abstract
Photocatalytic synthesis of hydrogen peroxide under mild reaction conditions is a promising technology. This article will review the recent research progress in the design of photocatalytic H2O2 synthesis systems. A comprehensive discussion of the strategies that could solve two essential issues related to H2O2 synthesis. That is, how to improve the reaction kinetics of H2O2 formation via 2e− oxygen reduction reaction and inhibit the H2O2 decomposition through a variety of surface functionalization methods. The photocatalyst design and the reaction mechanism will be especially stressed in this work which will be concluded with an outlook to show the possible ways for synthesizing high-concentration H2O2 solution in the future.
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- 2022
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4. Eco-Friendly Cerium–Cobalt Counter-Doped Bi2Se3 Nanoparticulate Semiconductor: Synergistic Doping Effect for Enhanced Thermoelectric Generation
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Jamal-Deen Musah, Siu Wing Or, Lingyan Kong, Vellaisamy A. L. Roy, and Chi-Man Lawrence Wu
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thermoelectric application ,energy conversion ,nanopartitulate ,eco-friendly material ,counter–doping ,Chemistry ,QD1-999 - Abstract
Metal chalcogenides are primarily used for thermoelectric applications due to their enormous potential to convert waste heat into valuable energy. Several studies focused on single or dual aliovalent doping techniques to enhance thermoelectric properties in semiconductor materials; however, these dopants enhance one property while deteriorating others due to the interdependency of these properties or may render the host material toxic. Therefore, a strategic doping approach is vital to harness the full potential of doping to improve the efficiency of thermoelectric generation while restoring the base material eco-friendly. Here, we report a well-designed counter-doped eco-friendly nanomaterial system (~70 nm) using both isovalent (cerium) and aliovalent (cobalt) in a Bi2Se3 system for enhancing energy conversion efficiency. Substituting cerium for bismuth simultaneously enhances the Seebeck coefficient and electrical conductivity via ionized impurity minimization. The boost in the average electronegativity offered by the self-doped transitional metal cobalt leads to an improvement in the degree of delocalization of the valence electrons. Hence, the new energy state around the Fermi energy serving as electron feed to the conduction band coherently improves the density of the state of conducting electrons. The resulting high power factor and low thermal conductivity contributed to the remarkable improvement in the figure of merit (zT = 0.55) at 473 K for an optimized doping concentration of 0.01 at. %. sample, and a significant nanoparticle size reduction from 400 nm to ~70 nm, making the highly performing materials in this study (Bi2−xCexCo2x3Se3) an excellent thermoelectric generator. The results presented here are higher than several Bi2Se3-based materials already reported.
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- 2023
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5. Studies on the Functional Properties of Titanium Dioxide Nanoparticles Distributed in Silyl–Alkyl Bridged Polyaniline-Based Nanofluids
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Chandravadhana Arumugam, Nandakumar Velu, Padmanaban Radhakrishnan, Vellaisamy A. L. Roy, Gopalan Anantha-Iyengar, Dong-Eun Lee, and Venkatramanan Kannan
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titanium dioxide ,polyaniline ,silyl–alkyl groups ,nanofluids ,thermal conductivity ,stability ,Chemistry ,QD1-999 - Abstract
In the present work, a new kind of nanocomposite (NC)-based solid component was prepared for formulating nanofluids (NFs). The NC comprised metal oxide (titanium dioxide, TiO2) dispersed in a conducting polymer with polyaniline (PANI) and chemically linked silyl–alkyl units in it (PSA) that were designated as T-PSA NC. The NFs with ethylene glycol (EG) as a base fluid were prepared with T-PSA NCs with various compositions of TiO2 and PSA as well for various concentrations of T-PSA NCs. The scanning electron microscopic evaluation of the NC revealed that PSA deposition on TiO2 nanoparticles (NPs) decreased particle agglomeration. The PSA coating on the TiO2 NPs did not influence the crystalline structure of the TiO2 NPs, according to the X-ray diffraction patterns. The thermophysical characterization and molecular interaction features of the NFs at 303 K including a novel inorganic–organic T-PSA NC, were detailed. Furthermore, the stability of the T-PSA NC-based NFs was investigated experimentally using the zeta potential, and the particle size distribution change was analyzed using the dynamic light scattering (DLS) method. The T-PSA NCs had particle sizes that were significantly bigger than pristine PSA and pure TiO2. Most of the preparation conditions used to produce the T-PSA NCs resulted in moderately stable suspensions in EG. The results revealed that the ultrasonic velocity increased with the increase in the concentration of T-PSA NC mass % in the NFs, the refractive index and thermal conductivity increased with the increase in the concentration, and the surface tension exhibited a linear change when the ratio of mass % concentration of the T-PSA NCs increased. The combined presence of components that synergistically contribute to the electro, thermal, optical, and rheological properties is expected to attract advanced applications for NFs.
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- 2023
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6. Investigation on the Direct and Bystander Effects in HeLa Cells Exposed to Very Low α‑Radiation Using Electrical Impedance Measurement
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AbdulMojeed O. Ilyas, Md Kowsar Alam, Jamal-Deen Musah, Mengsu Yang, Yun Wah Lam, Vellaisamy A. L. Roy, and Condon Lau
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Chemistry ,QD1-999 - Published
- 2021
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7. Isovalent substitution in metal chalcogenide materials for improving thermoelectric power generation – A critical review
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Jamal-Deen Musah, A. M. Ilyas, Shishir Venkatesh, Solomon Mensah, Samuel Kwofie, Vellaisamy A. L. Roy, and Chi-Man Lawrence Wu
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isovalent substitution ,thermoelectric (te) ,metal chalcogenides (mc) ,power factor (pf) ,figure of merit (zt) ,thermoelectric generator (teg) ,Chemistry ,QD1-999 ,Physics ,QC1-999 - Abstract
The adverse effect of fossil fuels on the environment is driving research to explore alternative energy sources. Research studies have demonstrated that renewables can offer a promising strategy to curb the problem, among which thermoelectric technology stands tall. However, the challenge with thermoelectric materials comes from the conflicting property of the Seebeck coefficient and the electrical conductivity resulting in a low power factor and hence a lower figure of merit. Researchers have reported various techniques to enhance the figure of merit, particularly in metal chalcogenide thermoelectric materials. Here we present a review on isovalent substitution as a tool to decouple the interdependency of the electrical conductivity and Seebeck coefficient to facilitate simultaneous enhancement in these two parameters. This is proven true in both cationic and anionic side substitutions in metal chalcogenide thermoelectric materials. Numerous publications relating to isovalent substitution in metal chalcogenide thermoelectric are reviewed. This will serve as a direction for current and future research to enhance thermoelectric performance and device application. This review substantiates the role of isovalent substitution in enhancing metal chalcogenide thermoelectric properties compared with conventional systems.
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- 2022
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8. Polyethylene Glycol Coated Magnetic Nanoparticles: Hybrid Nanofluid Formulation, Properties and Drug Delivery Prospects
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Rashmi Mannu, Vaithinathan Karthikeyan, Nandakumar Velu, Chandravadhana Arumugam, Vellaisamy A. L. Roy, Anantha-Iyengar Gopalan, Gopalan Saianand, Prashant Sonar, Kwang-Pill Lee, Wha-Jung Kim, Dong-Eun Lee, and Venkatramanan Kannan
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magnetic nanofluids ,drug delivery ,drug release models ,susceptibility ,Chemistry ,QD1-999 - Abstract
Magnetic nanoparticles (MNPs) are widely used materials for biomedical applications owing to their intriguing chemical, biological and magnetic properties. The evolution of MNP based biomedical applications (such as hyperthermia treatment and drug delivery) could be advanced using magnetic nanofluids (MNFs) designed with a biocompatible surface coating strategy. This study presents the first report on the drug loading/release capability of MNF formulated with methoxy polyethylene glycol (referred to as PEG) coated MNP in aqueous (phosphate buffer) fluid. We have selected MNPs (NiFe2O4, CoFe2O4 and Fe3O4) coated with PEG for MNF formulation and evaluated the loading/release efficacy of doxorubicin (DOX), an anticancer drug. We have presented in detail the drug loading capacity and the time-dependent cumulative drug release of DOX from PEG-coated MNPs based MNFs. Specifically, we have selected three different MNPs (NiFe2O4, CoFe2O4 and Fe3O4) coated with PEG for the MNFs and compared their variance in the loading/release efficacy of DOX, through experimental results fitting into mathematical models. DOX loading takes the order in the MNFs as CoFe2O4 > NiFe2O4 > Fe3O4. Various drug release models were suggested and evaluated for the individual MNP based NFs. While the non-Fickian diffusion (anomalous) model fits for DOX release from PEG coated CoFe2O4, PEG coated NiFe2O4 NF follows zero-order kinetics with a slow drug release rate of 1.33% of DOX per minute. On the other hand, PEG coated NiFe2O4 follows zero-order DOX release. Besides, several thermophysical properties and magnetic susceptibility of the MNFs of different concentrations have been studied by dispersing the MNPs (NiFe2O4, CoFe2O4 and Fe3O4) in the base fluid at 300 K under ultrasonication. This report on the DOX loading/release capability of MNF will set a new paradigm in view that MNF can resolve problems related to the self-heating of drug carriers during mild laser treatment with its thermal conducting properties.
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- 2021
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9. A β-cyclodextrin Modified Graphitic Carbon Nitride with Au Co-Catalyst for Efficient Photocatalytic Hydrogen Peroxide Production
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Guifu Zuo, Yuqian Zhang, Shanshan Liu, Zhaoliang Guo, Qiannan Zhao, Gopalan Saianand, Liwei Feng, Lijuan Li, Wangze Li, Ning Zhang, Xianguang Meng, and Vellaisamy A. L. Roy
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photocatalysis ,oxygen reduction reaction ,hydrogen peroxide ,graphitic carbon nitride ,β-cyclodextrin ,Chemistry ,QD1-999 - Abstract
Photocatalytic hydrogen peroxide (H2O2) production has attracted considerable attention as a renewable and environment-friendly method to replace other traditional production techniques. The performance of H2O2 production remains limited by the inertness of graphitic carbon nitride (CN) towards the adsorption and activation of O2. In this work, a photocatalyst comprising of β-cyclodextrin (β-CD)-modified CN with supporting Au co-catalyst (Au/β-CD-CN) has been utilized for effective H2O2 production under visible light irradiation. The static contact angle measurement suggested that β-CD modification increased the hydrophobicity of the CN photocatalyst as well as its affinity to oxygen gas, leading to an increase in H2O2 production. The rate of H2O2 production reached more than 0.1 mM/h under visible-light irradiation. The electron spin resonance spectra indicated that H2O2 was directly formed via a 2-electron oxygen reduction reaction (ORR) over the Au/β-CD-CN photocatalyst.
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- 2020
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10. Rapid nanomolding of nanotopography on flexible substrates to control muscle cell growth with enhanced maturation
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Xinge Yu, Vellaisamy A. L. Roy, Ho-Yin Chan, Wen J. Li, Chriss S. M. Chin, Qingyun Huang, and Cong Wu
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Myoblast proliferation ,Technology ,Myogenesis ,Chemistry ,Cell growth ,Materials Science (miscellaneous) ,Nanofabrication and nanopatterning ,Skeletal muscle ,Stimulation ,Condensed Matter Physics ,Engineering (General). Civil engineering (General) ,Industrial and Manufacturing Engineering ,Atomic and Molecular Physics, and Optics ,Article ,Nanostructures ,Extracellular matrix ,medicine.anatomical_structure ,medicine ,Biophysics ,Myocyte ,Nanotopography ,Electrical and Electronic Engineering ,TA1-2040 - Abstract
In vivo, multiple biophysical cues provided by highly ordered connective tissues of the extracellular matrix regulate skeletal muscle cells to align in parallel with one another. However, in routine in vitro cell culture environments, these key factors are often missing, which leads to changes in cell behavior. Here, we present a simple strategy for using optical media discs with nanogrooves and other polymer-based substrates nanomolded from the discs to directly culture muscle cells to study their response to the effect of biophysical cues such as nanotopography and substrate stiffness. We extend the range of study of biophysical cues for myoblasts by showing that they can sense ripple sizes as small as a 100 nm width and a 20 nm depth for myotube alignment, which has not been reported previously. The results revealed that nanotopography and substrate stiffness regulated myoblast proliferation and morphology independently, with nanotopographical cues showing a higher effect. These biophysical cues also worked synergistically, and their individual effects on cells were additive; i.e., by comparing cells grown on different polymer-based substrates (with and without nanogrooves), the cell proliferation rate could be reduced by as much as ~29%, and the elongation rate could be increased as much as ~116%. Moreover, during myogenesis, muscle cells actively responded to nanotopography and consistently showed increases in fusion and maturation indices of ~28% and ~21%, respectively. Finally, under electrical stimulation, the contraction amplitude of well-aligned myotubes was found to be almost 3 times greater than that for the cells on a smooth surface, regardless of the substrate stiffness.
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- 2021
11. S-scheme heterojunction g-C3N4/TiO2 with enhanced photocatalytic activity for degradation of a binary mixture of cationic dyes using solar parabolic trough reactor
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Mohammad Hossein Barzegar, Mehrorang Ghaedi, Hadi Heidari, Zohreh Moradi, Vellaisamy A. L. Roy, Vahid Madadi Avargani, and Mohammad Mehdi Sabzehmeidani
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Materials science ,Nanostructure ,General Chemical Engineering ,Composite number ,Heterojunction ,General Chemistry ,Catalysis ,chemistry.chemical_compound ,chemistry ,Chemical engineering ,Photocatalysis ,Parabolic trough ,Rhodamine B ,Degradation (geology) - Abstract
Developing photocatalytic systems by larger design to achieve degradation of dye pollutants by using solar light is highly desirable. Present work is devoted to the synthesis of step-scheme (S-scheme) g-C3N4/TiO2 heterojunction which subsequently employed for simultaneous degradation of a binary mixture of Methylene blue (MB) and Rhodamine B (RhB) solution in parabolic trough collectors (PTC) as continuous flow loop photoreactor. The as-prepared g-C3N4/TiO2 was analyzed by various techniques such as FE-SEM, EDS, XRD, FT-IR, BET, elements mapping and DRS. The composite central design (CCD) was applied to express mathematical relationships among variables such as process time, catalyst mass and initial concentrations of MB and RhB in the degradation process. The photocatalytic activity of the as-prepared composite is higher than pure TiO2 and g-C3N4 that is attributed to the positive synergetic effect of S-scheme between g-C3N4 and TiO2 nanostructure. Under solar irradiation in PTC, g-C3N4/TiO2 was able to degrade about 94.92 and 93.07% of binary mixture MB and RhB, respectively.
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- 2021
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12. BUFFER SYSTEMS BASED ON AMINOMETANESULPHONATE AND MONOETHANOLAMMONIUM N-ALKYLAMINOMETHANESULPHONATES
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А. А-А. Ennan, E. L. Roy, R.E. Khoma, L. T. Osadchiy, and T. S. Bienkovska
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Acidic Region ,Titration curve ,chemistry ,Potassium ,Lipophilicity ,Analytical chemistry ,Ionic bonding ,chemistry.chemical_element ,Atmospheric temperature range ,Aminomethanesulfonic acid ,Buffer (optical fiber) - Abstract
The limits of the pH buffering action (pHbuff) of YNHCH2SO3H – NH2CH2CH2OH –H2O (Y = H, CH3, HOCH2CH2, t-С4H9 and C6H5CH2) were determined and their buffer capacity (p) for monoethanolamine (MEA) was estimated in the temperature range 293–313 K. For systems with aminomethanesulfonic acid (AMSA), its N‑methyl, N‑hydroxyethyl (HEAMSA) and N‑benzyl (BzAMSA) derivatives, an increase in temperature leads to a decrease in the pH values of the lower limit of the buffering action of their solutions with monoethanolamine; in the case of N‑tert-butylaminomethanesulfonic acid (t-BuAMSA) – to an increase in the specified characteristic. An increase in temperature for systems with the most hydrophobic t-BuAMSA and BzAMSA (in comparison with other studied aminomethanesulfonic acids) leads to a decrease in the pH values of the upper limit of the buffer action. A decrease in the YNHCH2SO3H and NH2CH2CH2OH concentration leads to a shift in the boundaries of the pH of the buffering action to a more acidic region. The nature of the influence of the empirical function, combining their acid-base properties and lipophilicity (рKа + lgPow), on the concentration dependence of the buffer capacity according to MEA was revealed. It is shown that the buffering effect of the studied systems is due to the presence, in addition to the systems N‑alkylammoniummethanesulfonate – N‑alkylaminomethanesulfonate and 2-hydroxyethylammonium – monoethanolamine, ionic associates (pairs and triples). The position of the extrema on the graphical π=f(CMEA)/QYAMSA) dependencies for systems with hydrophilic AMSA and HEAMSA coincides with the position of the first minima on the differential titration curves dpH/dV = f(CMEA)/QYAMSA). Substitution of MEA to potassium aminomethanesulfonate leads to a shift in the pH buffering action to a more acidic region and increases the buffer capacity of the resulting systems.
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- 2021
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13. Investigation on the Direct and Bystander Effects in HeLa Cells Exposed to Very Low α‑Radiation Using Electrical Impedance Measurement
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Jamal-Deen Musah, Yun Wah Lam, Kowsar Alam, AbdulMojeed O. Ilyas, Vellaisamy A. L. Roy, Mengsu Yang, and Condon Lau
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biology ,Chemistry ,General Chemical Engineering ,medicine.medical_treatment ,General Chemistry ,Radiation ,biology.organism_classification ,Article ,Cell size ,HeLa ,Radiation therapy ,Cancer cell ,Biophysics ,medicine ,Bystander effect ,Irradiation ,QD1-999 ,Sampling interval - Abstract
The impact of radiation-induced bystander effect (RIBE) is still not well understood in radiotherapy. RIBEs are biological effects expressed by nonirradiated cells near or far from the irradiated cells. Most radiological studies on cancer cells have been based on biochemical characterization. However, biophysical investigation with label-free techniques to analyze and compare the direct irradiation effect and RIBE has lagged. In this work, we employed an electrical cell-indium tin oxide (ITO) substrate impedance system (ECIIS) as a bioimpedance sensor to evaluate the HeLa cells' response. The bioimpedance of untreated/nonirradiated HeLa (N-HeLa) cells, α-particle (Am-241)-irradiated HeLa (I-HeLa) cells, and bystander HeLa (B-HeLa) cells exposed to media from I-HeLa cells was monitored with a sampling interval of 8 s over a period of 24 h. Also, we imaged the cells at times where impedance changes were observed. Different radiation doses (0.5 cGy, 1.2 cGy, and 1.7 cGy) were used to investigate I-HeLa and B-HeLa cells' radiation-dose-dependence. By analyzing the changes in absolute impedance and cell size/number with time, compared to N-HeLa cells, B-HeLa cells mimicked the I-HeLa cells' damage and modification of proliferation rate. Contrary to the irradiated cells, the bystander cells' damage rate and proliferation rate enhancements have an inverse radiation-dose-response. Also, we report multiple RIBEs in HeLa cells in a single measurement and provide crucial insights into the RIBE mechanism without any labeling procedure. Unambiguously, our results have shown that the time-dependent control of RIBE is important during α-radiation-based radiotherapy of HeLa cells.
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- 2021
14. Recent developments on magnetic molecular imprinted polymers ( <scp>MMIPs</scp> ) for sensing, capturing, and monitoring pharmaceutical and agricultural pollutants
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Memed Duman, Chi-Chung Yeung, Vellaisamy A. L. Roy, Joel Kuhn, Elizabeth C. H. T. Lau, Gülgün Aylaz, and Humphrey H. P. Yiu
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Pollutant ,chemistry.chemical_classification ,Renewable Energy, Sustainability and the Environment ,Chemistry ,Environmental remediation ,General Chemical Engineering ,Organic Chemistry ,Extraction (chemistry) ,Sorption ,Polymer ,Pollution ,Inorganic Chemistry ,Fuel Technology ,Wastewater ,Environmental chemistry ,Waste Management and Disposal ,Biotechnology - Published
- 2021
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15. Carbon based materials: a review of adsorbents for inorganic and organic compounds
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Mehrorang Ghaedi, Vellaisamy A. L. Roy, Sahar Mahnaee, Hadi Heidari, and Mohammad Mehdi Sabzehmeidani
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Carbon nanofiber ,chemistry.chemical_element ,02 engineering and technology ,Carbon nanotube ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,law.invention ,Industrial wastewater treatment ,Adsorption ,chemistry ,Chemistry (miscellaneous) ,law ,Hazardous waste ,Environmental chemistry ,Biochar ,medicine ,General Materials Science ,0210 nano-technology ,Carbon ,Activated carbon ,medicine.drug - Abstract
This review presents the adsorptive removal process of hazardous materials onto carbon-based materials comprising activated carbon, graphene, carbon nanotubes, carbon nanofibers, biochar and carbon aerogels. Particular emphasis is placed on the fabrication of various carbon-based substances and their characteristics. As a ubiquitous phenomenon, dangerous compounds originating from industrial wastewater lead to damage to the environment and water resources. Therefore, among conventional technologies, adsorption is highly effective and the most extensively used method owing to its simplicity of performance and fairly low cost of application for the removal of hazardous pollutants. This paper comprehensively reviews a multitude of aspects regarding the chemical and physical nature of various carbon materials and their adsorption ability by increasing their surface area or their possible modification. Based on the properties of nano-carbon materials, adsorptive elimination mechanisms for antibiotics, dyes, heavy metals, pesticides, oils, phenolic and volatile organic compounds and gas pollutants are highlighted. The advantageous characteristics of nano-carbon materials assigned to their unique adsorptive removal of common hazardous substances will be pointed out.
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- 2021
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16. The Properties and SCR de‐NO x Application of Supported V 2 O 5 /TiO 2 Catalysts with Different Polymerization State of VO x Species Controlled by the pH Value of Their Precursors
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Lirong He, Shishi Wu, Vellaisamy A. L. Roy, Qing Tong, Shengcai Deng, Yining Fan, Jingjing Gong, Shuchao Li, Weijia Wang, Xiaolin Zhang, and Bolian Xu
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Polymerization ,Chemistry ,Inorganic chemistry ,Vanadium ,chemistry.chemical_element ,General Chemistry ,Value (mathematics) ,Redox ,NOx ,Catalysis - Published
- 2020
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17. The systematical detection and structure characterization of vanadium‐oxygen species in low concentration solutions by surface‐enhanced Raman spectroscopy experiments and density functional theory calculations
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Shishi Wu, Bolian Xu, Wang Weijia, Yining Fan, Lirong He, Shuchao Li, Xiaolin Zhang, Zhaoxu Chen, Xiaohong Li, and A. L. Roy Vellaisamy
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Materials science ,Analytical chemistry ,Vanadium ,chemistry.chemical_element ,Surface-enhanced Raman spectroscopy ,Oxygen ,Characterization (materials science) ,symbols.namesake ,chemistry ,symbols ,General Materials Science ,Density functional theory ,Raman spectroscopy ,Spectroscopy ,Volume concentration - Published
- 2020
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18. Photoredox Catalysis for the Fabrication of Water-Repellent Surfaces with Application for Oil/Water Separation
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Chi-Chiu Ko, Yelan Xiao, Zhen Shi, Yongyi Feng, Gary Tsui, Clement Manohar Arava, Shun-Cheung Cheng, Vellaisamy A. L. Roy, and Zhenjia Huang
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Aqueous solution ,Silanes ,Materials science ,Photoredox catalysis ,Propylamine ,Surfaces and Interfaces ,Condensed Matter Physics ,chemistry.chemical_compound ,chemistry ,Chemical engineering ,Attenuated total reflection ,Silanization ,Electrochemistry ,Photocatalysis ,Surface modification ,General Materials Science ,Spectroscopy - Abstract
Silanization processes with perfluoroalkyl silanes have been demonstrated to be effective in developing advanced materials with many functional properties, including hydrophobicity, water repellency, and self-cleaning properties. However, practical industrial applications of perfluoroalkyl silanes are limited by their extremely high cost. On the basis of our recent work on photoredox catalysis for amidation with perfluoroalkyl iodides, its application for surface chemical modification on filter paper, as an illustrative example, has been developed and evaluated. Before photocatalytic amidation, the surface is functionalized with amine functional groups by silanization with 3-(trimethoxysilyl)propylamine. All chemically modified surfaces have been fully characterized by attenuated total reflection infrared (ATR-IR), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy with energy-dispersive spectroscopy (SEM-EDS), and three-dimensional (3D) profiling to confirm the successful silanization and photocatalytic amidation. After surface modification of the filter papers with perfluoroalkanamide, they show high water repellency and hydrophobicity with contact angles over 120°. These filter papers possess high wetting selectivity, which can be used to effectively separate the organic and aqueous biphasic mixtures. The perfluoroalkanamide-modified filter papers can be used for separating organic/aqueous biphasic mixtures over many cycles without lowering the separating efficiency, indicating their reusability and excellent durability.
- Published
- 2021
19. Review on toxic effects of di(2-ethylhexyl) phthalate on zebrafish embryos
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Vellaisamy A. L. Roy, K.N. Yu, and Wing Sum Kwan
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phthalate ,endocrine system ,Health, Toxicology and Mutagenesis ,Physiology ,TP1-1185 ,Review ,Toxicology ,mono-2-ethylhexyl phthalate (MEHP) ,chemistry.chemical_compound ,di(2-ethylhexyl) phthalate (DEHP) ,Medicine ,Ingestion ,zebrafish embryo ,Zebrafish ,toxic effect ,Chemical Health and Safety ,Inhalation ,biology ,business.industry ,Chemical technology ,Embryogenesis ,Phthalate ,Embryonic Stage ,biology.organism_classification ,chemistry ,Toxicity ,Zebrafish embryo ,business - Abstract
Di(2-ethylhexyl) phthalate (DEHP) is widely used as a plasticizer in consumer products. People are continuously exposed to DEHP through ingestion, inhalation and dermal absorption. From epidemiological studies, DEHP has been shown to associate with various adverse health effects, such as reproductive abnormalities and metabolic diseases. Health concerns have been raised regarding DEHP exposures; therefore, relevant risk assessment has become necessary through toxicological testing of DEHP. In the past 10 years, an increasing number of DEHP toxicity studies have been using zebrafish embryos as an in vivo model due to their high fecundity, rapid embryonic development as well as optical transparency, which have now been established as an alternative of the more conventional rodent model. The aim of the present paper is to review the effects of acute (from embryo stage to ≤1 week) and chronic (from embryo stage to >1 week) DEHP exposures on zebrafish, which start from the embryonic stage, and to analyze acute and potential long-term effects induced by acute exposure and effects induced by chronic exposure of DEHP upon subjecting to exposures, starting from the embryonic stage to different developmental stages, with a view to facilitate risk assessments on DEHP exposures.
- Published
- 2021
20. Mechanochemical changes on cyclometalated Ir(<scp>iii</scp>) acyclic carbene complexes – design and tuning of luminescent mechanochromic transition metal complexes
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Yuen-Kiu Chun, Chi-Chiu Ko, Kin-Man Tang, Chi-On Ng, Jingqi Han, Shing-Lun Chan, Shek-Man Yiu, Vellaisamy A. L. Roy, Shun-Cheung Cheng, and Man-Kit Tse
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Materials science ,Solid-state ,Inorganic Chemistry ,chemistry.chemical_compound ,Crystallography ,symbols.namesake ,Transition metal ,chemistry ,symbols ,Phosphorescence ,Luminescence ,Raman spectroscopy ,Carbene ,Structural conformation - Abstract
A new class of luminescent mechanochromic cyclometalated Ir(III) complexes with pyridyl acyclic carbene ligands have been developed. These complexes shown predominant MLCT phosphorescence mixed with 3LC character. In the solid state and neat film, the emission of these complexes show significant red-shift upon mechanical grinding. On the basis of XRD, X-ray crystallography, Raman spectroscopy and DFT calculation, the mechanically-induced variations of the molecular packing and the structural conformation have been elucidated. With the understanding of their mechanochemical changes, it enables the design of luminescent mechanochromic compounds with tailored mechanochromic properties, including the emission color and the mechanochromic shift, through judicious structural modifications of the ligands as illustrated in the complexes reported in this work. It would also open up new design of mechanoresponsive materials.
- Published
- 2020
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21. Improving the chemical potential of nitrogen to tune the electron density and mobility of ZnSnN2
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Yizhu Xie, Vellaisamy A. L. Roy, Fan Ye, Dongping Zhang, Xing-Min Cai, Ping Fan, Karthikeyan Vaithinathan, Xiu-Fang Ma, and Qian-Qian Chen
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Range (particle radiation) ,Electron density ,Materials science ,Band gap ,Nearest neighbour ,chemistry.chemical_element ,02 engineering and technology ,General Chemistry ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Thermal conduction ,01 natural sciences ,Nitrogen ,0104 chemical sciences ,chemistry ,Chemical physics ,Sputtering ,Materials Chemistry ,Ionization energy ,0210 nano-technology - Abstract
To meet device applications, it is essential to fabricate nondegenerate ZnSnN2 with higher mobility. Herein, the chemical potential of nitrogen was improved under Zn-rich sputtering conditions and nondegenerate ZnSnN2 with mobility higher than 20 cm2 V−1 s−1 was successfully fabricated. The properties of the samples were characterized. The obtained ZnSnN2 is wurstite. Band conduction is observed in the range 300–100 K and nearest neighbour hopping is observed in the range 100–70 K. The forbidden band gap is about 1.43 eV and Sn substituting Zn is the major donor, whose ionization energy is 34.6 meV. Improving the chemical potential of nitrogen under Zn-rich conditions effectively changes the off-stoichiometry of ZnSnN2 and unintentionally increases oxygen doping, which finally leads to a decrease in electron density and an increase in mobility.
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- 2020
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22. Simultaneous Enhancement of Thermopower and Electrical Conductivity through Isovalent Substitution of Cerium in Bismuth Selenide Thermoelectric Materials
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Travis G. Novak, Clement Manohar Arava, Wei Xu, Xianfeng Chen, S. V. Novikov, Liyao Liu, Kwok Ho Lam, Chi-Man Lawrence Wu, Seokwoo Jeon, A.M. Ilyas, Asaduzzaman, D. S. Nikulin, Jamal-Deen Musah, Vellaisamy A. L. Roy, and Xiao Yanjun
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Electron mobility ,Materials science ,Condensed matter physics ,chemistry.chemical_element ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Thermoelectric materials ,01 natural sciences ,0104 chemical sciences ,chemistry.chemical_compound ,Cerium ,chemistry ,Electrical resistivity and conductivity ,Seebeck coefficient ,Thermoelectric effect ,Figure of merit ,General Materials Science ,Bismuth selenide ,0210 nano-technology - Abstract
It is challenging to achieve highly efficient thermoelectric materials due to the conflicts between thermopower (Seebeck coefficient) and electrical conductivity. These parameters are the core factors defining the thermoelectric property of any material. Here, we report the use of isovalent substitution as a tool to decouple the interdependency of the Seebeck coefficient and the electrical properties of cerium-doped bismuth selenide thermoelectric material. With this strategy, we can achieve a simultaneous increase in both the electrical conductivity and the Seebeck coefficient of the material by tuning the concentration of cerium doping, due to formation of neutral impurities and consequently the improvement of carrier mobility. Our theoretical calculation reveals a downward shift of the valence band with cerium concentration, which influences the thermoelectric enhancement of the synthesized materials. Finally, an order of magnitude enhancement of the figure of merit is obtained due to isovalent substitution, thus providing a new avenue for enhancing the thermoelectric performance of materials.
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- 2019
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23. Efficient oxygen electroreduction kinetics by titanium carbide@nitrogen doped carbon nanocomposite
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Vellaisamy A. L. Roy, Haridas B. Parse, Sagar Ingavale, Bhalchandra Kakade, Clement Manohar, and Indrajit M. Patil
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Materials science ,Kinetics ,Energy Engineering and Power Technology ,chemistry.chemical_element ,02 engineering and technology ,010402 general chemistry ,Electrocatalyst ,01 natural sciences ,Oxygen ,law.invention ,Catalysis ,Metal ,chemistry.chemical_compound ,Electron transfer ,law ,Titanium carbide ,Renewable Energy, Sustainability and the Environment ,Graphene ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,0104 chemical sciences ,Fuel Technology ,chemistry ,Chemical engineering ,visual_art ,visual_art.visual_art_medium ,0210 nano-technology - Abstract
A simple approach towards preparation of non-noble metal electrocatalyst for oxygen reduction reaction in low temperature fuel cells has been necessity for a sustainable green technology. Herein, a cost-effective and facile method of preparation of TiC@N-doped graphene like carbon nanocomposite (TiC@NC) has been discussed. The composite structure of as-prepared TiC@NC was confirmed using structural analysis and morphological studies. Interestingly, the optimized TiC@NC(0.2)-800 electrocatalyst shows remarkable oxygen reduction reaction (ORR) kinetics with better onset potential +1.08 vs RHE and significant current density of 4.8 mA/cm2 in alkaline medium. Further, obtained catalyst exhibits four electron transfer mechanism similar to Pt-based electrocatalysts. Additionally, TiC@NC(0.2)-800 shows better mass activity (∼410 mA/mg) as compared to other compositions. Moreover, the single step kinetics mechanism has been seen due to lower (
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- 2019
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24. Study on synthesis, characterization, and nonvolatile memory behavior of ferrocene-containing metallopolymers
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Hongen Guo, Asaduzzaman, Zheng Zhong, Xiaozhe Cheng, Qingchen Dong, Vellaisamy A. L. Roy, and Hong Lian
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Bistability ,010405 organic chemistry ,business.industry ,Organic Chemistry ,Fluorene ,010402 general chemistry ,Photochemistry ,01 natural sciences ,Biochemistry ,Porphyrin ,0104 chemical sciences ,Resistive random-access memory ,Inorganic Chemistry ,Non-volatile memory ,chemistry.chemical_compound ,chemistry ,Ferrocene ,Write once read many ,Computer data storage ,Materials Chemistry ,Physical and Theoretical Chemistry ,business - Abstract
In this work, two metallopolymers (P1 and P2) were designed and synthesized through coupling of ferrocene-anchored fluorene derivatives with porphyrin and benzene based diethynyl ligand, respectively. The chemical structure and physical properties of these two metallpolymers were fully characterized, which indicate that these two metallopolymers are thermally stable and semiconducting. Then, sandwich-like organic resistive memory based on P1 and P2 for data storage were explored. The memory device testing results manifest that both P1 and P2 are of the stable electric bistability and show write once read many times memory (WORM) characteristics.
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- 2019
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25. The Mediating Role of Impulsivity Between Psychological Distress and Alcohol Misuse Among College Students at a Historically Black University
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Nicole H. Weiss, Amanda L. Roy, Shannon R. Forkus, Megan M. Risi, Joseph S. Rossi, and Robert G. Laforge
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Adult ,Male ,Universities ,education ,030508 substance abuse ,Alcohol ,Psychological Distress ,Impulsivity ,Article ,Young Adult ,03 medical and health sciences ,chemistry.chemical_compound ,0302 clinical medicine ,medicine ,Humans ,Students ,Psychological distress ,Alcohol Drinking in College ,United States ,030227 psychiatry ,Black or African American ,Psychiatry and Mental health ,chemistry ,Diagnosis, Dual (Psychiatry) ,Impulsive Behavior ,Female ,medicine.symptom ,0305 other medical science ,Psychology ,Clinical psychology - Abstract
OBJECTIVE: Alcohol misuse is prevalent and clinically significant among college students. Psychological distress is one factor that has been found to predict alcohol misuse in this population. However, relatively few investigations examined the association of psychological distress to alcohol misuse or its underlying mechanisms among students attending Historically Black Colleges and Universities (HBCUs). The present study examined whether impulsivity explains the relation between psychological distress and alcohol misuse in this population using structural equation modeling. METHODS: Participants were 287 undergraduate students attending an HBCU in the southern United States (M(age) = 22.5, 66.3% female, 93.7% Black). RESULTS: Impulsivity was found to significantly mediate the association of psychological distress to alcohol misuse, such that higher levels of psychological distress were associated with greater impulsivity which, in turn, was related to more alcohol misuse. Further analyses indicated that attentional impulsivity significantly mediated the association of psychological distress to alcohol misuse. CONCLUSION: These findings suggest the utility of targeting impulsivity in interventions aimed at preventing and reducing alcohol misuse among college students attending HBCUs who experience psychological distress.
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- 2019
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26. Ecofriendly UV-protective films based on poly(propylene carbonate) biocomposites filled with TiO2 decorated lignin
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Robert K.Y. Li, Xianwu Cao, Wei Wu, Bin Wang, Vellaisamy A. L. Roy, Tao Liu, Qijun Sun, Xueqin Deng, and Yanhong Feng
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0303 health sciences ,Aqueous solution ,Materials science ,Composite number ,02 engineering and technology ,General Medicine ,Dynamic mechanical analysis ,021001 nanoscience & nanotechnology ,Biochemistry ,Miscibility ,03 medical and health sciences ,chemistry.chemical_compound ,chemistry ,Chemical engineering ,Structural Biology ,Propylene carbonate ,Lignin ,Thermal stability ,0210 nano-technology ,Glass transition ,Molecular Biology ,030304 developmental biology - Abstract
It is highly desirable to develop biodegradable UV-shielding materials from the renewable resources as the ever-increasing demand for the sustainable environment. In this work, TiO2 decorated lignin particles (TiO2@lignin) were synthesized successfully by hydrothermal method in aqueous solution to improve the UV shielding performance of lignin particles. The poly(propylene carbonate) (PPC) composite films (thickness of ~23 μm) with different contents of TiO2@lignin were prepared via a blade-casting method. Morphological analysis showed that the TiO2@lignin dispersed uniformly in the PPC matrix with a good miscibility. UV–vis transmission spectra results revealed that the PPC composite film containing 5 wt% TiO2@lignin could absorb about 90% of UV light in the full UV band (200–400 nm), indicating the TiO2@lignin had a good UV-shielding property. Moreover, the presence of TiO2@lignin could significantly improve the thermal stability of the PPC/TiO2@lignin composite films. The DMA results showed that the introduction of TiO2@lignin could enhance the storage modulus and glass transition temperature simultaneously.
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- 2019
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27. Finely dispersed Au nanoparticles on graphitic carbon nitride as highly active photocatalyst for hydrogen peroxide production
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Hui Song, Shanshan Liu, Yi Du, Peixiao Zong, Xianguang Meng, Weishu Hou, Zhaoliang Guo, Bingdong Li, Tao Wang, Liang Wang, Vellaisamy A. L. Roy, and Guifu Zuo
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Inert ,Materials science ,010405 organic chemistry ,Process Chemistry and Technology ,Graphitic carbon nitride ,Nanoparticle ,General Chemistry ,010402 general chemistry ,01 natural sciences ,Decomposition ,Catalysis ,0104 chemical sciences ,law.invention ,chemistry.chemical_compound ,chemistry ,Chemical engineering ,law ,Photocatalysis ,Hydrogen peroxide ,Electron paramagnetic resonance - Abstract
In this work, graphitic carbon nitride (g-C3N4) supporting finely dispersed Au nanoparticles is developed as a simple and efficient photocatalyst for H2O2 production under visible light irradiation. Au nanoparticle cocatalyst remarkably enhances photocatalytic activity of C3N4 for H2O2 production. Due to the inert nature to catalyze the decomposition of H2O2, Au/C3N4 also exhibits stable H2O2 evolution rate. It is of great interest that the maximal H2O2 production activity is reached at the loading amount of Au as low as 0.01%, revealing the great catalytic efficacy of highly dispersed Au cocatalyst during the photocatalytic H2O2 synthesis and the possibility to produce concentrated H2O2 using C3N4 with extremely low Au loading amount. The in situ electron spin resonance studies reveal that the H2O2 is produced through direct 2e− oxygen reduction over Au/C3N4 photocatalyst.
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- 2019
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28. Deposition-rate controlled nitrogen-doping into cuprous oxide and its thermal stability
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Xing-Min Cai, Yi-Bin Qiu, Dongping Zhang, Fan Ye, Huan Wang, Vellaisamy A. L. Roy, Bo Wang, Jun-Jie Zeng, and Ping Fan
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010302 applied physics ,Materials science ,Annealing (metallurgy) ,Metals and Alloys ,Oxide ,Analytical chemistry ,chemistry.chemical_element ,02 engineering and technology ,Surfaces and Interfaces ,Conductivity ,021001 nanoscience & nanotechnology ,01 natural sciences ,Nitrogen ,Copper ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,chemistry.chemical_compound ,chemistry ,Sputtering ,Electrical resistivity and conductivity ,0103 physical sciences ,Materials Chemistry ,Thin film ,0210 nano-technology - Abstract
Cuprous oxide has important applications from photovoltaic devices to photocatalysis and nitrogen-doping can improve the p-type conductivity of cuprous oxide. Here, phase-pure cuprous oxide thin films are prepared by sputtering a copper target in the atmosphere of Ar, O2 and N2 with the sputtering pressure varying from 0.6 Pa–3.0 Pa. The samples deposited at 0.6 Pa is also annealed in the flow of Ar or Ar plus N2. The results show that sputtering pressure below 1.0 Pa results in higher deposition rate and more nitrogen incorporation into cuprous oxide while sputtering pressure of 3.0 Pa leads to lower deposition rate and no nitrogen doping though the gas flow rates are the same. In nitrogen-doped Cu2O, nitrogen exists as β-N (atomic nitrogen), α-N2 (-N=N-) and γ-N2 (N N). Annealing completely removes β-N and partially turns α-N2 into γ-N2. Nitrogen-doped cuprous oxide has smaller resistivity and larger hole density than undoped samples. The longest time for the absorbed nitrogen molecules to stay on the copper position is estimated to be 8.45 × 10−7 s. Annealing has little effect on the electrical and optical properties of nitrogen-doped cuprous oxide though it induces a weak decomposition.
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- 2019
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29. Au modified Bi2O3-TiO2 hybrid for photocatalytic synthesis of hydrogen peroxide
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Guifu Zuo, Yuqi Xiao, Vellaisamy A. L. Roy, Qiannan Zhao, Lijuan Li, Bingdong Li, Yuqian Zhang, Liwei Feng, and Xianguang Meng
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Materials science ,Charge separation ,Process Chemistry and Technology ,H2O2 ,Au/TiO2 ,Bi2O3 ,Heterojunction ,General Chemistry ,Catalysis ,law.invention ,chemistry.chemical_compound ,Improved performance ,Chemistry ,chemistry ,Chemical engineering ,law ,Photocatalysis ,Oxygen reduction reaction ,Hydrogen peroxide ,Electron paramagnetic resonance ,QD1-999 ,Single-electron ORR - Abstract
In this work, an Au modified Bi2O3-TiO2 (Au/Bi2O3-TiO2) hybrid is developed as a simple and effective photocatalyst for the production of H2O2. The modification of Bi2O3 improves the charge separation of photocatalyst and significantly enhances the photocatalytic activity of Au/TiO2 for H2O2 production. In-situ electron spin resonance studies shows stepwise single-electron oxygen reduction reaction (ORR) on the Au/Bi2O3-TiO2 photocatalyst for the production of H2O2. This work demonstrates the importance of heterojunction structure photocatalyst for improved performance of TiO2 in order to produce concentrated H2O2.
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- 2021
30. Portable molecularly imprinted polymer-based platform for detection of histamine in aqueous solutions
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Jin Hua Li, Tan Li, Vellaisamy A. L. Roy, Shishir Venkatesh, Siu Chuen Lau, Qijun Sun, Chi-Chung Yeung, Ling-Yi Li, and Michael H.W. Lam
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Biogenic Amines ,Environmental Engineering ,Health, Toxicology and Mutagenesis ,Inflammatory response ,0211 other engineering and technologies ,02 engineering and technology ,010501 environmental sciences ,01 natural sciences ,Molecular Imprinting ,chemistry.chemical_compound ,Molecularly Imprinted Polymers ,Environmental Chemistry ,Waste Management and Disposal ,0105 earth and related environmental sciences ,021110 strategic, defence & security studies ,Aqueous solution ,Chromatography ,integumentary system ,Molecularly imprinted polymer ,food and beverages ,Limiting ,Pollution ,chemistry ,Molecular imprinting ,Histamine - Abstract
Histamine, which is a naturally occurring chemical in seafood, is known to cause undesirable inflammatory response when consumed in large amounts. Histamine is produced in unsafe amounts in colored seafood when improperly stored for just a few hours. Food and health regulatory bodies across the world have guidelines limiting the amount of histamine in fresh as well as processed seafood. Conventional histamine detection is performed in testing labs, which is a slow process and results in bottlenecks in the seafood supply-chain system. A system to rapidly detect the seafood histamine levels on site is very desirable for seafood suppliers. Herein, we describe an impedance-based histamine detection sensor built on a flexible substrate that can detect histamine in the range of 100–500 ppm. Moreover, our sensor discriminates histamine in the presence of DL-histidine and other biogenic amines, with the selectivity provided by molecular imprinting technology. As a proof of concept, a smartphone controlled, portable semi-quantitative histamine sensing device was fabricated that gave out reliable testing results for histamine in different test solutions as well as for real seafood. We believe this technology can be extended towards determination of other food contaminants in aqueous solutions.
- Published
- 2021
31. Highly Sensitive and Cost-Effective Portable Sensor for Early Gastric Carcinoma Diagnosis
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Shishir Venkatesh, Xianfeng Chen, Vellaisamy A. L. Roy, Vaithinathan Karthikeyan, Clement Manohar Arava, Spoorthy Pathikonda, Peter K.N. Yu, Saw Lin Oo, and Terrence Chi-Kong Lau
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cancer early detection ,Cost-Benefit Analysis ,Early detection ,02 engineering and technology ,Gastric carcinoma ,010402 general chemistry ,lcsh:Chemical technology ,01 natural sciences ,Biochemistry ,Article ,Analytical Chemistry ,polycarbonate membrane ,Stomach Neoplasms ,Cancer screening ,RNA modification ,medicine ,Biomarkers, Tumor ,Humans ,lcsh:TP1-1185 ,Antigens, Tumor-Associated, Carbohydrate ,Electrical and Electronic Engineering ,Instrumentation ,Oligo RNA ,Early Detection of Cancer ,Chemistry ,Carcinoma ,RNA ,Cancer ,021001 nanoscience & nanotechnology ,medicine.disease ,Atomic and Molecular Physics, and Optics ,0104 chemical sciences ,Highly sensitive ,Carcinoembryonic Antigen ,Cancer antigen ,Cancer research ,cancer antigen ,0210 nano-technology ,electrical current sensor - Abstract
Facile and efficient early detection of cancer is a major challenge in healthcare. Herein we developed a novel sensor made from a polycarbonate (PC) membrane with nanopores, followed by sequence-specific Oligo RNA modification for early gastric carcinoma diagnosis. In this design, the gastric cancer antigen CA72-4 is specifically conjugated to the Oligo RNA, thereby inhibiting the electrical current through the PC membrane in a concentration-dependent manner. The device can determine the concentration of cancer antigen CA72-4 in the range from 4 to 14 U/mL, possessing a sensitivity of 7.029 µAU−1mLcm−2 with a linear regression (R2) of 0.965 and a lower detection limit of 4 U/mL. This device has integrated advantages including high specificity and sensitivity and being simple, portable, and cost effective, which collectively enables a giant leap for cancer screening technologies towards clinical use. This is the first report to use RNA aptamers to detect CA72-4 for gastric carcinoma diagnosis.
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- 2021
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32. Wearable and flexible thin film thermoelectric module for multi-scale energy harvesting
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Xianfeng Chen, Venkataraman Kannan, Vellaisamy A. L. Roy, Vaithinathan Karthikeyan, James Utama Surjadi, Joseph Chung Kai Wong, Yang Lu, and Kwok Ho Lam
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Materials science ,Thin films ,Thermal resistance ,Energy Engineering and Power Technology ,02 engineering and technology ,010402 general chemistry ,01 natural sciences ,chemistry.chemical_compound ,Electrical and Electronic Engineering ,Physical and Theoretical Chemistry ,Thin film ,Flexible thermoelectric generator ,Renewable Energy, Sustainability and the Environment ,business.industry ,Energy conversion efficiency ,Wearable electronics ,021001 nanoscience & nanotechnology ,0104 chemical sciences ,Lead telluride ,Tin telluride ,Thermoelectric generator ,chemistry ,Physical vapor deposition ,Thermal sensor ,Optoelectronics ,0210 nano-technology ,business ,Energy harvesting - Abstract
Developing a thermoelectric generator(TEG) with shape conformable geometry for sustaining low-thermal\ud impedance and large temperature gradient (ΔT) is fundamental for wearable and multi-scale energy harvesting applications. Here we demonstrate a flexible architectural design, with efficient thin film thermoelectric\ud generator as a solution for this problem. This approach not only decreases the thermal impedance but also\ud multiplies the temperature gradient, thereby increasing the power conversion efficiency (PCE) as comparable to\ud bulk TEG. Intact thin films of Tin telluride (p-type) and Lead Telluride (n-type) are deposited on flexible substrate\ud through physical vapor deposition and a thermoelectric module possessing a maximum output power density of\ud 8.4 mW/cm2 is fabricated. We have demonstrated the performance of p-SnTe/n-PbTe based TEG as a flexible\ud wearable power source for electronic gadgets, as a thermal touch sensor for real-time switching and temperature\ud monitoring for exoskeleton applications.
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- 2020
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33. Improved polyvinylpyrrolidone microneedle arrays with non-stoichiometric cyclodextrin
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Guangyu Zhu, Wei Chen, Li Yan, Vellaisamy A. L. Roy, Long-Biao Huang, Xinrui Niu, Bing Chen, Xianfeng Chen, Bruce K. Gale, K.N. Yu, Xiaoyue Zhu, Chong Wang, and Himanshu J. Sant
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chemistry.chemical_classification ,Materials science ,Absorption of water ,Cyclodextrin ,Polyvinylpyrrolidone ,Biocompatibility ,Biomedical Engineering ,Nanotechnology ,General Chemistry ,General Medicine ,Polymer ,chemistry ,Chemical engineering ,Drug delivery ,medicine ,General Materials Science ,Glass transition ,Dissolution ,medicine.drug - Abstract
Dissolving polymer microneedles have attracted much attention for their biocompatibility, fast dissolution, and high drug loading. Among them, polyvinylpyrrolidone (PVP) is widely used, but its high water absorption and poor mechanical properties constrain its broad applications. Herein we show that adding cyclodextrin (CD) to form PVP–CD inclusion complexes can alleviate these problems. The water absorption of PVP was reduced by 36–40% at different RHs as the PVP–CD inclusion complexes formed. Attractively, the water absorption at 10 and 20 days remained almost the same for the complexes while it could dramatically increase for the pure PVP samples, particularly in high humidity environments, indicating a possibly longer storage time for the complexes. It was also found that the Young's modulus and hardness of the PVP–CD could be greatly improved, especially for low molecular weight PVP. Furthermore, the glass transition temperature (Tg) of the PVP–CD increased by up to 39 °C. With the improved properties, the fabricated PVP–CD microneedles possessed much sharper needle tips and the patch had less cracks than those made from pure PVP. Pig skin application results suggested that the PVP–CD microneedle arrays were able to reliably pierce the stratum corneum of the skin while it was not achievable for the PVP microneedles with the same geometry. We anticipate that these PVP–CD complex microneedles are more suitable for vaccine and drug delivery because of their superior properties.
- Published
- 2020
34. Synergetic enhancement on flame retardancy by melamine phosphate modified lignin in rice husk ash filled P34HB biocomposites
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Ruichao Wei, Tao Liu, He Haibing, Richard K.K. Yuen, Shishir Venkatesh, Qijun Sun, Robert K.Y. Li, Wei Wu, Xianwu Cao, and Vellaisamy A. L. Roy
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Materials science ,General Engineering ,02 engineering and technology ,Dynamic mechanical analysis ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Miscibility ,Husk ,0104 chemical sciences ,chemistry.chemical_compound ,chemistry ,Chemical engineering ,Ultimate tensile strength ,Ceramics and Composites ,Lignin ,Thermal stability ,Char ,Composite material ,0210 nano-technology ,Melamine - Abstract
Lignin can be employed as a sustainable functional additive and reinforcement filler for polymers. In this work, melamine phosphate modified lignin (MAP-lignin) was synthesized as a bio-based halogen-free flame-retardant agent. The synergetic effects between MAP-lignin and rice husk ash (RHA) on the thermal stability, dynamic mechanical performance and flame-retardant properties of the poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (P34HB) biocomposites were investigated. The results revealed that MAP-lignin and RHA could significantly increase the char residue and MAP-lignin had a good miscibility with P34HB. The incorporation of MAP-lignin and RHA as stiff fillers could enhance the storage modulus of the P34HB matrix. Moreover, the tensile strength and elongation at break of the P34HB/RHA composite could be improved due to the MAP-lignin could serve as a compatibilizer to improve the interaction between RHA and P34HB. Cone calorimetry data demonstrated that the addition of 30 wt% MAP-lignin and 5 wt% RHA reduced the peak heat release rate (PHRR) and total heat release (THR) of P34HB noticeably by 42.8 and 24.3%, respectively. In addition, the CO2 production rate and CO concentration could be significantly suppressed by the addition of MAP-lignin. The enhanced flame retardancy of P34HB composite should be ascribed to the barrier effect of the increased char residue with compact and intact structure, as well as the released gases from the decomposition of melamine.
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- 2018
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35. Biodegradable skin-inspired nonvolatile resistive switching memory based on gold nanoparticles embedded alkali lignin
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Robert K.Y. Li, Wei Wu, Shishir Venkatesh, Su-Ting Han, Vellaisamy A. L. Roy, Haiyan Peng, Qijun Sun, Chi-Chung Yeung, and Ye Zhou
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Materials science ,Nanotechnology ,02 engineering and technology ,Substrate (electronics) ,010402 general chemistry ,01 natural sciences ,Biomaterials ,chemistry.chemical_compound ,Materials Chemistry ,Lignin ,Electronics ,Electrical and Electronic Engineering ,business.industry ,General Chemistry ,Biodegradation ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,0104 chemical sciences ,Electronic, Optical and Magnetic Materials ,Resistive random-access memory ,Active layer ,chemistry ,Colloidal gold ,Computer data storage ,0210 nano-technology ,business - Abstract
Natural biomaterials are capable of producing biodegradable and/or biocompatible electronic devices for vast applications such as next-generation green data storage. Here, we demonstrate an environment-friendly alkali lignin as a favourable candidate for resistive switching memory storage applications. The resistive memory devices based on gold nanoparticles embedded alkali lignin (Au NPs:lignin) exhibits a typical write-once-read-many-times memory (WORM) resistive switching behaviour with a large on-off ratio (>104), and long data retention characteristics (>103 s) under low power operation (4.7 V). Au NPs acting as trapping sites in the active layer are responsible for the resistive switching mechanism. The active layer is fabricated on organic substrates through facile solution-processed methods under normal ambient conditions. The skin-inspired polylactide (PLA) film is utilized as an ultrathin substrate endowing the memory devices with good mechanical support and biodegradability. This work opens up new avenues towards renewable and environmentally benign lignin-based materials for biodegradable electronic devices.
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- 2018
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36. Fabrication of octamethyl substituted zinc(II) phthalocyanine nanostructure via exfoliation and use for solution-processed field-effect transistor
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Qikun Hu, Zong-Xiang Xu, Vellaisamy A. L. Roy, Haiquan Shan, Yaomiao Feng, Lei Dong, Wenkang Ye, Yulong Wang, Xize Sun, and Jiaju Xu
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Nanostructure ,Materials science ,chemistry.chemical_element ,02 engineering and technology ,General Chemistry ,Zinc ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,Exfoliation joint ,0104 chemical sciences ,Electronic, Optical and Magnetic Materials ,Biomaterials ,chemistry.chemical_compound ,Crystallinity ,Chemical engineering ,chemistry ,Monolayer ,Materials Chemistry ,Phthalocyanine ,Field-effect transistor ,Electrical and Electronic Engineering ,Thin film ,0210 nano-technology - Abstract
Ultrathin nanocrystals with thicknesses of only several monolayers and even a single monolayer were prepared via exfoliation by ultrasound from an octamethyl substituted zinc(II) phthalocyanine (ZnMe2Pc). The drop-casted thin films of these nanocrystals exhibited higher crystallinity than that of the vacuum-deposited film. The drop-casted field-effect transistor based on these nanocrystals showed a significant increase in charge carrier mobility because of enhanced intermolecular π-π stacking in the ultrasonic-treated ZnMe2Pc, and the measured mobility was two orders of magnitude higher than that of the vacuum-deposited transistor.
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- 2018
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37. Selective and sensitive onsite detection of phthalates in common solvents
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Shishir Venkatesh, Jiaqing Zhuang, Robert K.Y. Li, Vellaisamy A. L. Roy, Qijun Sun, Chi-Chung Yeung, and Tan Li
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Materials science ,Chromatography ,010401 analytical chemistry ,Metals and Alloys ,Phthalate ,Molecularly imprinted polymer ,02 engineering and technology ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,0104 chemical sciences ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,chemistry.chemical_compound ,Functional monomer ,chemistry ,Adverse health effect ,Materials Chemistry ,Field based ,Electrical and Electronic Engineering ,0210 nano-technology ,Instrumentation ,Volume concentration - Abstract
Phthalates, which are proven to have adverse health effects, are globally restricted for use in all kinds of plastics through various regulations. Although there are laboratory based techniques for phthalate detection, there is a pressing need for a field based technique so samples can be pre-screened. Here, we report a molecularly imprinted polymer (MIP) functionalized extended gate field effect transistor (EGFET) as a field sensor to identify di-2-ethlyhexyl phthalate (DEHP), which is the one of the most commonly used phthalate. In DI water, DEHP is detected at the extremely low concentration of 25 μg/L while exhibiting excellent selectivity. We are able to tune the linear dynamic range of the sensor by synthesizing the MIP with a different monomer-to-template ratio and by choice of the functional monomer. Finally, the sensor is calibrated for DEHP in artificial saliva at sub 50 μg/L, showing applicability in phthalate migration tests, which are used in assessing the safety of plastic toys. Furthermore, our sensor platform can be further extended to identify other phthalates as fast pre-screening tool.
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- 2018
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38. Single-Component Oligomer Nanoparticle-Based Size-Dependent Dual-Emission Modulation
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Chun-Sing Lee, Vellaisamy A. L. Roy, Wei Liu, Mingliang Sun, Xin Song, Feng Li, and Liangmin Yu
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Aqueous solution ,Photoluminescence ,Materials science ,business.industry ,Nanoparticle ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Fluorescence ,Oligomer ,0104 chemical sciences ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,chemistry.chemical_compound ,General Energy ,Förster resonance energy transfer ,chemistry ,Excited state ,Optoelectronics ,Physical and Theoretical Chemistry ,0210 nano-technology ,business ,Common emitter - Abstract
Multichromophoric oligomers offer a versatile platform for nanoparticle multicolor fluorescent modulation. A donor–acceptor–donor (D–A–D) type oligomer (DDBTD), with blue emitting antenna and red emitting core, is chosen to assemble into fluorescent colloidal nanoparticles (FCNs) using a nanoprecipitation method. By modulating the DDBTD concentrations in good solvent, the DDBTD nanoparticles with average diameters ranging from sub-10 to 300 nm are obtained by the nanoprecipitation process in aqueous solution. Interestingly, multicolor photoluminescence (PL) can be realized from bright blue (∼440 nm) to rose red (∼630 nm) based on FCNs size control. The size-dependent PL originates from the aggregation-enhanced fluorescence resonance energy transfer (FRET) from diphenyl-aminofluorenyl antenna unit (blue emitter) to benzothiadiazole-based core (red emitter). Furthermore, the lifetime measurement of the FCNs in excited state shows a size-dependent behavior, which confirms that the size-dependent multicolor P...
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- 2018
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39. Efficient heat batteries for performance boosting in solar thermal cooking module
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Le Thi Thu Thuy, Vaithinathan Karthikeyan, Sukruedee Sukchai, Vellaisamy A. L. Roy, Quach An Binh, Karthikeyan Velmurugan, S.M. Santhi Rekha, Venkatramanan Kannan, and Kuaanan Techato
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Work (thermodynamics) ,Boosting (machine learning) ,Materials science ,Renewable Energy, Sustainability and the Environment ,business.industry ,Strategy and Management ,Enthalpy of fusion ,Nuclear engineering ,food and beverages ,Building and Construction ,Temperature cycling ,Industrial and Manufacturing Engineering ,Magnesium nitrate ,chemistry.chemical_compound ,chemistry ,Thermal ,business ,Operational stability ,Thermal energy ,General Environmental Science - Abstract
Heat batteries show outstanding charging and discharging thermal energy capability with the latent heat of fusion (Hm) for solar thermal application. In this work, novel magnesium nitrate hexahydrate (MNH) based heat batteries are fabricated and tested for 1000 sequential thermal cycles. The MNH heat batteries demonstrate a high level of operational stability with the least corrosive rate. Real-time performance of the heat batteries was studied by incorporating them in the parabolic solar thermal cooking module. The developed MNH heat batteries based solar cooking module illustrates excellent heat retention capacity over 6 h after the sunshine. Temperature profiles under no load and full load conditions reveal the moderation and enhancement in the solar thermal cooking module's operational efficiencies. The solar cooking module's efficiency with the heat batteries reaches a maximum of 22.8% and 42.5%, under no load and full load conditions, respectively. Real-time cooking capacity with different edible materials under both outdoor and indoor environments proves the effective performance. Further, it is estimated that MNH heat batteries can be in full performance for a minimum of 2 years with maintenance-free and emission-free operations.
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- 2021
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40. Polypyridyl chromium(<scp>iii</scp>) complexes for non-volatile memory application: impact of the coordination sphere on memory device performance
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Ganesamoorthi Ramar, Balamurugan Kandasamy, Su-Ting Han, Chi-Chiu Ko, Li Zhou, Zong-Xiang Xu, Shun-Cheung Cheng, Vellaisamy A. L. Roy, and Shishir Venkatesh
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Resistive touchscreen ,Materials science ,Coordination sphere ,Silicon ,chemistry.chemical_element ,Nanotechnology ,02 engineering and technology ,General Chemistry ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,Resistive random-access memory ,Non-volatile memory ,Chromium ,chemistry ,Transition metal ,Materials Chemistry ,Molecular memory ,0210 nano-technology - Abstract
Molecular non-volatile memory devices are deemed to offer remarkable features such as low-cost, high retention times and low power consumption that could possibly catapult their implementation over the contemporary silicon-based devices. Although scattered examples of small molecules, particularly transition metal complexes with rich electrochemical behavior, have been demonstrated to show promising performance in memory device application, systematic study on the molecular design and the structure–property relationship is lacking. Moreover, studies on memory applications of transition metal complexes have been mainly confined to those of precious metals. These have hindered the development and the practical applications of molecular non-volatile memory devices. To improve the practical applicability of transition metal complex-based molecular memory devices, herein, we report the study of memory applications of various solution-processable and earth-abundant polypyridyl Cr(III) complexes. Some of the fabricated resistive random-access memory (RRAM) devices exhibit reversible bipolar switching, high ON/OFF ratio and long retention time. It is anticipated that this study will provide important insights on the molecular design of transition metal complexes for memory device applications and would lead to a new generation of economically accessible and sustainable non-volatile memory devices.
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- 2018
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41. Experimental Investigations and Surface Morphology of Bio-Micromachining on Copper
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L. Roy, N. Arul Manikandan, Kannan Pakshirajan, M. Ravi Sankar, and Abhishek Singh
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0209 industrial biotechnology ,Materials science ,Manufacturing process ,Metallurgy ,chemistry.chemical_element ,Material removal ,02 engineering and technology ,Photochemical machining ,021001 nanoscience & nanotechnology ,Copper ,Acidithiobacillus ferrooxidans ,Surface micromachining ,020901 industrial engineering & automation ,Machining ,chemistry ,Vickers hardness test ,0210 nano-technology - Abstract
Bio-micromachining is an emerging latest non-traditional manufacturing process and has various advantages. In this manufacturing process micro-organisms are used for material removal in desired shape and size. Acidithiobacillus ferrooxidans micro-organism are used as a tool for machining the copper workpiece and the effects of various parameters like pH, temperature, shaking speed, machining time are being calculated and there optimized value is being purposed. Vickers hardness test was also being performed and comparative study between bio-micromachining and photochemical machining is done in this paper.
- Published
- 2018
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42. Organometal halide perovskite as hole injection enhancer in organic light-emitting diode
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Yulong Wang, Qikun Hu, Vellaisamy A. L. Roy, Lei Dong, Zong-Xiang Xu, Haiquan Shan, Xize Sun, Jiaju Xu, and Yaomiao Feng
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Materials science ,Fabrication ,Halide ,02 engineering and technology ,010402 general chemistry ,01 natural sciences ,Styrene ,Biomaterials ,chemistry.chemical_compound ,Materials Chemistry ,OLED ,Electrical and Electronic Engineering ,Diode ,Perovskite (structure) ,business.industry ,General Chemistry ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,0104 chemical sciences ,Electronic, Optical and Magnetic Materials ,Indium tin oxide ,chemistry ,Optoelectronics ,Chemical stability ,0210 nano-technology ,business - Abstract
We introduce an organometal halide perovskite (CH3NH3PbI3), as a hole injection layer (HIL) to accelerate hole injection and transport in tris-(8-hydroxyquinoline) aluminum-based organic light-emitting diodes (OLEDs). The excellent charge mobility of CH3NH3PbI3 along with the better interface contacts induced by the CH3NH3PbI3 HIL improved the charge balance and thus enhanced device performance compared with that of OLEDs without a HIL and with a poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) HIL. Maximum luminance of 19110 cd m−2 and power efficiency of 3.210 lm W−1 were obtained. Also, besides more balanced charge recombination, the non-aqueous fabrication of the perovskite HIL and the chemical stability of indium tin oxide in contact with CH3NH3PbI3 led to increased device stability and durability, giving a half-life time as long as 31.7 h.
- Published
- 2017
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43. Photophysical, Cellular‐Uptake, and Bioimaging Studies of Luminescent Ruthenium(II)–Polypyridine Complexes Containing a <scp>d</scp> ‐Fructose Pendant
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Kenneth Kam-Wing Lo, Vellaisamy A. L. Roy, Chris Tsan-Shing Lau, Christina Chan, and Kenneth Yin Zhang
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biology ,010405 organic chemistry ,Stereochemistry ,Glucose transporter ,chemistry.chemical_element ,010402 general chemistry ,Photochemistry ,biology.organism_classification ,01 natural sciences ,humanities ,0104 chemical sciences ,Ruthenium ,law.invention ,Inorganic Chemistry ,HeLa ,Bipyridine ,chemistry.chemical_compound ,chemistry ,Confocal microscopy ,law ,Lipophilicity ,Cytotoxicity ,Luminescence - Abstract
Two luminescent ruthenium(II) polypyridine complexes appended with a D-fructose unit, [Ru(N^N)2(bpy-fructose)](PF6)2 (bpy-fructose = 4-(1-deoxy-D-fructos-1-yl)aminocarbonyl-4'-methyl-2,2'-bipyridine; N^N = 4,7-diphenyl-1,10-phenanthroline (Ph2-phen) (1a) and 2,2'-bipyridine (bpy) (2a)) and their D-fructose-free counterparts [Ru(N^N)2(bpy-Et)](PF6)2 (bpy-Et = 4-ethylaminocarbonyl-4'-methyl-2,2'-bipyridine; N^N = Ph2-phen (1b) and bpy (2b)) were synthesized and characterized. The photophysical properties, lipophilicity, cytotoxicity, and cellular uptake of the complexes were studied. Laser-scanning confocal microscopy revealed that both complexes 1a and 1b displayed intense membrane staining toward human breast adenocarcinoma (MCF-7) cells. However, while complex 1a retained its membrane-staining characteristic when incubated with human cervix epithelioid carcinoma (HeLa) cells, complex 1b was localized in the mitochondria. Additionally, fructose-dependent cellular uptake experiments suggested that complex 1a was transported into MCF-7 cells via a glucose transporter (GLUT)-mediated pathway.
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- 2017
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44. Doping cuprous oxide with fluorine and its band gap narrowing
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Dongping Zhang, Xiao-Qiang Su, Jun Zhang, Bo Wang, Jun-Jie Zeng, Xiao-Qing Tian, Ping Fan, Fan Ye, Jian-Wei Li, Xing-Min Cai, Vellaisamy A. L. Roy, and Huan Wang
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Materials science ,Band gap ,Inorganic chemistry ,Oxide ,Analytical chemistry ,02 engineering and technology ,01 natural sciences ,Condensed Matter::Materials Science ,chemistry.chemical_compound ,Lattice constant ,Electrical resistivity and conductivity ,Condensed Matter::Superconductivity ,0103 physical sciences ,Materials Chemistry ,Thin film ,010302 applied physics ,Valence (chemistry) ,business.industry ,Mechanical Engineering ,Doping ,Metals and Alloys ,021001 nanoscience & nanotechnology ,Semiconductor ,chemistry ,Mechanics of Materials ,Condensed Matter::Strongly Correlated Electrons ,0210 nano-technology ,business - Abstract
Phase-pure cuprous oxide (Cu 2 O) thin films doped with Fluorine (F) have been prepared under thermal diffusion at diffusion temperatures of 1123 K and 1223 K and it is found that higher diffusion temperature leads to larger grain size. F-doping slightly reduces the lattice constant and F-doped Cu 2 O thin films exhibit p-type semiconductor characteristics. The reduction of band gap occurs due to F-doping induced impurity band, because F-doped samples have larger Urbach tails than that of undoped samples. Theoretical calculation demonstrates that substitutional F-doping makes Cu 2 O almost metallic because the energy bands of F atoms enter the forbidden gap, and interstitial F-doping narrows the band gap because F atoms contribute to the valence bands. The doped F atoms are very possibly interstial and play the role of acceptors in Cu 2 O. Phase-pure Cu 2 O doped with F have smaller resistivity and larger hole concentration, implying potential application in solar cells.
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- 2017
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45. A Novel Type of Aqueous Dispersible Ultrathin-Layered Double Hydroxide Nanosheets for in Vivo Bioimaging and Drug Delivery
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Wei Chen, Xianfeng Chen, Long-Biao Huang, Wenjun Zhang, Li Yan, Vellaisamy A. L. Roy, Xiujuan Zhang, and Mengjiao Zhou
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Materials science ,Nanoparticle ,Nanotechnology ,02 engineering and technology ,engineering.material ,010402 general chemistry ,01 natural sciences ,Nanomaterials ,Mice ,chemistry.chemical_compound ,Drug Delivery Systems ,Hydroxides ,Rhodamine B ,Animals ,Tissue Distribution ,General Materials Science ,Layered double hydroxides ,021001 nanoscience & nanotechnology ,Nanostructures ,0104 chemical sciences ,Methotrexate ,chemistry ,Drug delivery ,engineering ,Nanoparticles ,Surface modification ,Hydroxide ,0210 nano-technology ,Ethylene glycol - Abstract
Layered double hydroxide (LDH) nanoparticles have been widely used for various biomedical applications. However, because of the difficulty of surface functionalization of LDH nanoparticles, the systemic administration of these nanomaterials for in vivo therapy remains a bottleneck. In this work, we develop a novel type of aqueous dispersible two-dimensional ultrathin LDH nanosheets with a size of about 50 nm and a thickness of about 1.4 to 4 nm. We are able to covalently attach positively charged rhodamine B fluorescent molecules to the nanosheets, and the nanohybrid retains strong fluorescence in liquid and even dry powder form. Therefore, it is available for bioimaging. Beyond this, it is convenient to modify the nanosheets with neutral poly(ethylene glycol) (PEG), so the nanohybrid is suitable for drug delivery through systemic administration. Indeed, in the test of using these nanostructures for delivery of a negatively charged anticancer drug, methotrexate (MTX), in a mouse model, dramatically improved therapeutic efficacy is achieved, indicated by the effective inhibition of tumor growth. Furthermore, our systematic in vivo safety investigation including measuring body weight, determining biodistribution in major organs, hematology analysis, blood biochemical assay, and hematoxylin and eosin stain demonstrates that the new material is biocompatible. Overall, this work represents a major development in the path of modifying functional LDH nanomaterials for clinical applications.
- Published
- 2017
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46. Size Controllable and Surface Tunable Zeolitic Imidazolate Framework-8–Poly(acrylic acid sodium salt) Nanocomposites for pH Responsive Drug Release and Enhanced in Vivo Cancer Treatment
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Xiaoyue Zhu, Long-Biao Huang, Xianfeng Chen, Wei Chen, Li Yan, Wenjun Zhang, Peter K.N. Yu, Guangyu Zhu, Zhigang Wang, Mengjiao Zhou, Xiujuan Zhang, and Vellaisamy A. L. Roy
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Materials science ,Biocompatibility ,Nanotechnology ,02 engineering and technology ,010402 general chemistry ,01 natural sciences ,Nanocomposites ,Mice ,chemistry.chemical_compound ,Imidazolate ,Animals ,General Materials Science ,Acrylic acid ,Nanocomposite ,Sodium ,Imidazoles ,Hydrogen-Ion Concentration ,021001 nanoscience & nanotechnology ,0104 chemical sciences ,Drug Liberation ,Acrylates ,chemistry ,Blood chemistry ,Drug delivery ,Zeolites ,Surface modification ,0210 nano-technology ,Zeolitic imidazolate framework - Abstract
Nanoscale size controllable and surface modifiable zeolitic imidazolate framework-8-poly(acrylic acid sodium salt) (ZIF-8-PAAS) nanocomposites are fabricated by employing PAAS nanospheres as a soft template. These ZIF-8-PAAS nanocomposites have different sizes ranging from 30 to 200 nm and exhibit different crystallinity, and pH sensitivity. These nanocomposites can be employed as vectors to deliver doxorubicin for anticancer therapy, leading to greatly enhanced drug therapeutic efficacy when tested in cell lines and mice model. Systematic toxicity investigation including hematoxylin and eosin staining analysis of tumor and major organs, hematology analysis, and blood chemistry analysis indicates that the nanocomposites possess high biocompatibility. This work provides a strategy to make metal-organic frameworks (MOFs) nanocomposites with size tunability in nanoscale and flexible surface modification for various applications.
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- 2017
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- View/download PDF
47. Pre- and post-treatments free nanocomposite based hole transport layer for high performance organic solar cells with considerably enhanced reproducibility
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Xingang Ren, Wallace C. H. Choy, Jian Mao, Chunjun Liang, Vellaisamy A. L. Roy, Hugh L. Zhu, Jiaqi Cheng, and Jiaqing Zhuang
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chemistry.chemical_classification ,Materials science ,Fabrication ,Nanocomposite ,Organic solar cell ,Renewable Energy, Sustainability and the Environment ,Photovoltaic system ,Energy conversion efficiency ,Nanotechnology ,02 engineering and technology ,Electron acceptor ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,chemistry ,PEDOT:PSS ,Chemical engineering ,General Materials Science ,Work function ,Electrical and Electronic Engineering ,0210 nano-technology - Abstract
In this work, we demonstrate a one-step room-temperature ethanol-processed nickel oxide (NiOx):electron acceptor nanocomposite functioning as efficient hole transport layer (HTL). Specifically, one-step refers to the formation of the nanocomposite HTL films without extra steps of pre-treatments of ITO nor post-treatments of HTL films, and thus considerably reduce the fabrication complexity and cost. By varing the concentration of the electron acceptor, 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4-TCNQ), the work function (WF) of the nanocomposite films can be widely tuned from 4.73eV to 5.30 eV, which favors its use for photovoltaic applications of organic donor materials with different highest energy occupied molecular orbital (HOMO) energy levels. Organic solar cells (OSCs) have been fabricated by using the NiOx:F4-TCNQ nanocomposite as HTL. The optimized average power conversion efficiency (PCE) of NiOx:F4-TCNQ based OSCs can be 18% better than that of one-step prepared poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid) (PEDOT:PSS) based OSCs. Remarkably, NiOx:F4-TCNQ based OSCs show better reproducibility as the deviation of PCE values can be improved by a greatest extent of 10 times. This work contributes towards simple and low-cost fabrication of high efficiency OSCs for practical photovoltaic applications.
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- 2017
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48. Effect of nitrogen-doped graphene on morphology and properties of immiscible poly(butylene succinate)/polylactide blends
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ChengKen Wu, Vellaisamy A. L. Roy, Xianwu Cao, Jiaqing Zhuang, Robert K.Y. Li, Wei Wu, Li Zhou, Haiyan Peng, and Qijun Sun
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chemistry.chemical_classification ,Nanocomposite ,Materials science ,Mechanical Engineering ,02 engineering and technology ,Polymer ,Compatibilization ,Dynamic mechanical analysis ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Industrial and Manufacturing Engineering ,0104 chemical sciences ,Polybutylene succinate ,chemistry.chemical_compound ,Crystallinity ,chemistry ,Mechanics of Materials ,Ultimate tensile strength ,Ceramics and Composites ,Thermal stability ,Composite material ,0210 nano-technology - Abstract
Plastic pollution has become a serious issue to the ecosystem, and biodegradable poly (butylene succinate)/polylactide (PBS/PLA) blends are regarded as the promising eco-friendly alternatives to replace the non-degradable plastics based on fossil fuels. Yet, the thermodynamically immiscible nature of PBS and PLA hinders their extended applications. In this contribution, nitrogen-doped graphene (NG) was introduced into immiscible PBS/PLA blends by melt compounding. The incorporation of NG in PBS/PLA (70/30 wt%) blends was observed to significantly improve the geometrical morphology and reduce the domain size of the dispersed PLA phase, indicating a compatibilization effect of NG on the immiscible blends. The TEM micrographs showed that the NG mainly dispersed in the PBS matrix while a small amount was located in PLA phase. When the NG concentration increased to 1.0 wt%, the NG filled PBS/PLA nanocomposites exhibited an obvious improvement in the storage modulus and loss modulus in comparison with the pristine PBS/PLA blend. The thermal stability of the PBS/PLA/NG nanocomposites was enhanced monotonously with an increase of the NG concentration, due to the barrier effect of NG and good interaction between the NG and polymer matrices. Moreover, the NG was noticed to act as a nucleating agent to significantly improve the PBS crystallinity without affecting the crystal forms of PBS and PLA. The tensile strength, tensile modulus and elongation at break of the blends could be enhanced by the low concentration of NG.
- Published
- 2017
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49. Fabrication and properties of pure-phase Cu2O co-doped with zinc and indium
- Author
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Jun-Jun Xiao, Jingting Luo, Xing-Min Cai, Zhuanghao Zheng, Guangxing Liang, Ping Fan, Fan Ye, Vellaisamy A. L. Roy, Dongping Zhang, and Xiao-Qiang Su
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Materials science ,Band gap ,Mechanical Engineering ,Metallurgy ,Doping ,Alloy ,Metals and Alloys ,Analytical chemistry ,chemistry.chemical_element ,02 engineering and technology ,Zinc ,engineering.material ,Sputter deposition ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,chemistry ,Mechanics of Materials ,Sputtering ,Materials Chemistry ,engineering ,Thin film ,0210 nano-technology ,Indium - Abstract
Cuprous oxide (Cu 2 O) thin films co-doped with zinc (Zn) and indium (In) were fabricated with direct current (DC) magnetron sputtering. The sputtering voltage of the Cu target was fixed while that of the alloy target of Zn and In was varied. It is found that when the alloy target voltage is below 310 V, pure-phase Cu 2 O can be obtained while a further increase in the alloy target voltage will result in the presence of metallic copper. The surface morphologies, the atomic ratios of the Zn and In, and the grain size do not have a linear dependence on the sputtering voltage of the alloy target. Higher concentration doping will decrease the lattice constant of Cu 2 O. Pure-phase samples doped with Zn and In have relatively higher transmittance and larger optical band gaps. The n-type conduction of Cu 2 O co-doped with Zn and In is realized when the sputtering voltage of the alloy target is 310 V. Zn and In atoms are found to exist as Zn 2+ and In 3+ in the films and they are possible donors for the n-type conduction.
- Published
- 2017
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50. Gating a Single Cell: A Label-Free and Real-Time Measurement Method for Cellular Progression
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Peter K.N. Yu, Shishir Venkatesh, Vaithinathan Karthikeyan, Chi Chung Yeung, Saw Lin Oo, Abdul Mojeed Ilyas, Xianfeng Chen, Vellaisamy A. L. Roy, Eva Yi Kong, and Clement Manohar Arava
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In situ ,Time Factors ,Cells ,Cell ,Apoptosis ,Gating ,010402 general chemistry ,01 natural sciences ,Mass Spectrometry ,Analytical Chemistry ,HeLa ,medicine ,Tumor Cells, Cultured ,Humans ,Electrodes ,Ions ,Measurement method ,biology ,Chemistry ,potassium ,010401 analytical chemistry ,Cancer ,medicine.disease ,biology.organism_classification ,0104 chemical sciences ,Membrane ,medicine.anatomical_structure ,Cancer cell ,Biophysics ,Irradiation ,Single-Cell Analysis ,HeLa Cells - Abstract
There is an ever-growing need for more advanced methods to study the response of cancer cells to new therapies. To determine cancer cells' response from a cell-mortality perspective to various cancer therapies, we report a label-free and real time method to monitor the in situ response of individual HeLa cells using a single cell gated transistor (SCGT). As a cell undergoes apoptotic cell death, it experiences changes in morphology and ion concentrations. This change is well in line with the threshold voltage of the SCGT, which has been verified by correlating the data with the cell morphologies by scanning electron microscopy and the ion-concentration analysis by inductively-coupled plasma mass spectrometry (ICPMS). This SCGT could replace patch clamps to study single cell activity via direct measurement in real time. Importantly, this SCGT can be used to study the electrical response of a single cell to stimuli that leaves the membrane intact.
- Published
- 2020
- Full Text
- View/download PDF
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