Displaying publications 161 - 180 of 311 in total

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  1. Nanostructure-assisted charge transfer in α-Fe2O3/g-C3N4 heterojunctions for efficient and highly stable photoelectrochemical water splitting
    Arzaee NA, Mohamad Noh MF, Mohd Ita NSH, Mohamed NA, Mohd Nasir SNF, Nawas Mumthas IN, et al.
    Dalton Trans, 2020 Aug 28;49(32):11317-11328.
    PMID: 32760991 DOI: 10.1039/d0dt00683a
    The development of semiconductor heterojunctions is a promising and yet challenging strategy to boost the performance in photoelectrochemical (PEC) water splitting. This paper describes the fabrication of a heterojunction photoanode by coupling α-Fe2O3 and g-C3N4via aerosol-assisted chemical vapour deposition (AACVD) followed by spin coating and air annealing. Enhanced PEC performance and stability are observed for the α-Fe2O3/g-C3N4 heterojunction photoanode in comparison to pristine α-Fe2O3 and the reason is systematically discussed in this paper. Most importantly, the fabricated α-Fe2O3/g-C3N4 film shows impressive stability, retaining more than 90% of the initial current over 12 h operating time. The excellent stability of the heterojunction photoanode is achieved due to the unique nanoflake structure of α-Fe2O3 induced by AACVD. This nanostructure promotes good adhesion with the g-C3N4 particles, as the particles tend to be trapped within the α-Fe2O3 valleys and eventually create strong and large interfacial contacts. This leads to improved separation of charge carriers at the α-Fe2O3/g-C3N4 interface and suppression of charge recombination in the photoanode, which are confirmed by the transient decay time, charge transfer efficiency and electrochemical impedance analysis. Our findings demonstrate the importance of nanostructure engineering for developing heterojunction structures with efficient charge transfer dynamics.
    Matched MeSH terms: Nanostructures
  2. Cytocompatibility of Titanium Microsphere-Based Surfaces
    Huang X, Shan L, Cheng K, Weng W
    ACS Biomater Sci Eng, 2017 Dec 11;3(12):3254-3260.
    PMID: 33445368 DOI: 10.1021/acsbiomaterials.7b00551
    The topography at the micro/nanoscale level for biomaterial surfaces has been thought to play vital roles in their interactions with cells. However, discovering the interdisciplinary mechanisms underlying how cells respond to micro-nanostructured topography features still remains a challenge. In this work, ∼37 μm 3D printing used titanium microspheres and their further hierarchical micro-nanostructured spheres through hydrothermal treatment were adopted to construct typical model surface topographies to study the preosteoblastic cell responses (adhesion, proliferation, and differentiation). We here demonstrated that not only the hierarchical micro-nanostructured surface topography but also their distribution density played critical role on cell cytocompatibility. The microstructured topography feature surface with middle-density distributed titanium microspheres showed significantly enhanced cell responses, which might be attributed to the better cellular interaction due to the cell aggregates. However, the hierarchical micro-nanostructured topography surface, regardless of the distribution density of titanium microspheres, improved the cell-surface interactions because of the enhanced initial protein adsorption, thereby reducing the cell aggregates and consequently their responses. This work, therefore, provides new insights into the fundamental understanding of cell-material interactions and will have a profound impact on further designing micro-nanostructured topography surfaces to control cell responses.
    Matched MeSH terms: Nanostructures
  3. Chitin nanocrystals based complex fluids: A green nanotechnology
    Kumar S, Foroozesh J
    Carbohydr Polym, 2021 Apr 01;257:117619.
    PMID: 33541647 DOI: 10.1016/j.carbpol.2021.117619
    Chitin biopolymer has received significant attention recently by many industries as a green technology. Nanotechnology has been used to make chitin nanocrystals (ChiNCs) that are rod-shaped natural nanomaterials with nanoscale size. Owing to the unique features such as biodegradability, biocompatibility, renewability, rod-shape, and excellent surface and interfacial, physiochemical, and thermo-mechanical properties; ChiNCs have been green and attractive products with wide applications specifically in medical and pharmaceutical, food and packaging, cosmetic, electrical, and electronic, and also in the oil and gas industry. This review aims to give a comprehensive and applied insight into ChiNCs technology. It starts with reviewing different sources of chitin and their extraction methods followed by the characterization of ChiNCs. Furthermore, a detailed investigation into various complex fluids (dispersions, emulsions, foams, and gels) stabilized by ChiNCs and their characterisation have been thoroughly deliberated. Finally, the current status including ground-breaking applications, untapped investigations, and future prospective have been presented.
    Matched MeSH terms: Nanostructures
  4. Perspectives and advancements in the design of nanomaterials for targeted cancer theranostics
    Tan YY, Yap PK, Xin Lim GL, Mehta M, Chan Y, Ng SW, et al.
    Chem Biol Interact, 2020 Sep 25;329:109221.
    PMID: 32768398 DOI: 10.1016/j.cbi.2020.109221
    Cancer continues to be one of the most challenging diseases to be treated and is one of the leading causes of deaths around the globe. Cancers account for 13% of all deaths each year, with cancer-related mortality expected to rise to 13.1 million by the year 2030. Although, we now have a large library of chemotherapeutic agents, the problem of non-selectivity remains the biggest drawback, as these substances are toxic not only to cancerous cells, but also to other healthy cells in the body. The limitations with chemotherapy and radiation have led to the discovery and development of novel strategies for safe and effective treatment strategies to manage the menace of cancer. Researchers have long justified and have shed light on the emergence of nanotechnology as a potential area for cancer therapy and diagnostics, whereby, nanomaterials are used primarily as nanocarriers or as delivery agents for anticancer drugs due to their tumor targeting properties. Furthermore, nanocarriers loaded with chemotherapeutic agents also overcome biological barriers such as renal and hepatic clearances, thus improving therapeutic efficacy with lowered morbidity. Theranostics, which is the combination of rationally designed nanomaterials with cancer-targeting moieties, along with protective polymers and imaging agents has become one of the core keywords in cancer research. In this review, we have highlighted the potential of various nanomaterials for their application in cancer therapy and imaging, including their current state and clinical prospects. Theranostics has successfully paved a path to a new era of drug design and development, in which nanomaterials and imaging contribute to a large variety of cancer therapies and provide a promising future in the effective management of various cancers. However, in order to meet the therapeutic needs, theranostic nanomaterials must be designed in such a way, that take into account the pharmacokinetic and pharmacodynamics properties of the drug for the development of effective carcinogenic therapy.
    Matched MeSH terms: Nanostructures
  5. Sustainable mixed matrix membranes containing porphyrin and polysulfone polymer for acid gas separations
    Saqib S, Rafiq S, Muhammad N, Khan AL, Mukhtar A, Ullah S, et al.
    J Hazard Mater, 2021 06 05;411:125155.
    PMID: 33858108 DOI: 10.1016/j.jhazmat.2021.125155
    The synergetic effect of nitrogen-rich and CO2-philic filler and polymer in mixed matrix-based membranes (MMMs) can separate CO2 competently. The introduction of well-defined nanostructured porous fillers of pores close to the kinetic diameter of the gas molecule and polymer matrix compatibility is a challenge in improving the gas transportation characteristics of MMMs. This study deals with the preparation of porphyrin filler and the polysulfone (PSf) polymer MMMs. The fillers demonstrated uniform distribution, uniformity, and successful bond formation. MMMs demonstrated high thermal stability with a glass transition temperature in the range of 480-610 °C. The porphyrin filler exhibited microporous nature with the presence of π-π bonds and Lewis's basic functionalities between filler-polymer resulted in a highly CO2-philic structure. The pure and mixed gas permeabilities and selectivity were successfully improved and surpass the Robeson's upper bound curve's tradeoff. Additionally, the temperature influence on CO2 permeability revealed lower activation energies at higher temperatures leading to the gas transport facilitation. This can be granted consistency and long-term durability in polymer chains. These results highlight the unique properties of porphyrin fillers in CO2 separation mixed matrix membranes and offer new knowledge to increase comprehension of PSf performance under various contents or environments.
    Matched MeSH terms: Nanostructures
  6. ZnO microstructures and nanostructures prepared by sol-gel hydrothermal technique
    Kamaruddin SA, Chan KY, Sahdan MZ, Rusop M, Saim H
    J Nanosci Nanotechnol, 2010 Sep;10(9):5618-22.
    PMID: 21133082
    Zinc oxide (ZnO) is an emerging material in large area electronic applications such as thin-film solar cells and transistors. We report on the fabrication and characterization of ZnO microstructures and nanostructures. The ZnO microstructures and nanostructures have been synthesized using sol-gel immerse technique on oxidized silicon substrates. Different precursor's concentrations ranging from 0.0001 M to 0.01 M (M=molarity) using zinc nitrate hexahydrate [Zn(NO3)2. 6H2O] and hexamethylenetetramine [C6H12N4] were employed in the synthesis of the ZnO structures. The surface morphologies were examined using scanning electron microscope (SEM) and atomic force microscope (AFM). In order to investigate the structural properties, the ZnO microstructures and nanostructures were measured using X-ray diffractometer (XRD). The optical properties of the ZnO structures were measured using photoluminescence (PL) and ultraviolet-visible (UV-Vis) spectroscopies.
    Matched MeSH terms: Nanostructures
  7. Electrical and optical properties of nanostructured zinc oxide thin films influenced by annealing temperature
    Shariffudin SS, Mamat MH, Rusop M
    J Nanosci Nanotechnol, 2012 Oct;12(10):8165-8.
    PMID: 23421195
    Transparent nanostructured ZnO thin films were successfully deposited using sol-gel spin coating method on a quartz substrate. The 0.4 M ZnO solution gel was prepared using zinc acetate dihydrate (Zn(CH3COO)22H2O) as the precursor, 2-methoxyethanol as the solvent and monoethanolamine (MEA) as the stabilizer. The electrical and optical properties dependencies on the annealing temperature of the nanostructured ZnO thin films were investigated. It was found that as the annealing temperature increased, the particle size, conductivity and the peak of the UV emission also increased.
    Matched MeSH terms: Nanostructures
  8. Fulltext Mass production of highly-porous graphene for high-performance supercapacitors
    Amiri A, Shanbedi M, Ahmadi G, Eshghi H, Kazi SN, Chew BT, et al.
    Sci Rep, 2016 09 08;6:32686.
    PMID: 27604639 DOI: 10.1038/srep32686
    This study reports on a facile and economical method for the scalable synthesis of few-layered graphene sheets by the microwave-assisted functionalization. Herein, single-layered and few-layered graphene sheets were produced by dispersion and exfoliation of functionalized graphite in ethylene glycol. Thermal treatment was used to prepare pure graphene without functional groups, and the pure graphene was labeled as thermally-treated graphene (T-GR). The morphological and statistical studies about the distribution of the number of layers showed that more than 90% of the flakes of T-GR had less than two layers and about 84% of T-GR were single-layered. The microwave-assisted exfoliation approach presents us with a possibility for a mass production of graphene at low cost and great potentials in energy storage applications of graphene-based materials. Owing to unique surface chemistry, the T-GR demonstrates an excellent energy storage performance, and the electrochemical capacitance is much higher than that of the other carbon-based nanostructures. The nanoscopic porous morphology of the T-GR-based electrodes made a significant contribution in increasing the BET surface as well as the specific capacitance of graphene. T-GR, with a capacitance of 354.1 Fg(-1) at 5 mVs(-1) and 264 Fg(-1) at 100 mVs(-1), exhibits excellent performance as a supercapacitor.
    Matched MeSH terms: Nanostructures
  9. Fulltext Effect of annealing temperatures on the formation of silicon nanostructures prepared by thermal evaporation
    Aspaniza Ahmad, Hutagalung, Sabar D.
    Journal of Nuclear and Related Technologies, 2009;2009(1):217-223.
    MyJurnal
    Silicon nanostructures have successfully been synthesized by thermal evaporation technique using nickel catalyst. Silicon powder served as starting source material was evaporated at high temperature (900-1100°C) in inert carrier gas. The grown silicon nanostructures were collected on (111) silicon substrate surface that positioned at varied location from source material. By controlling heating rate, gas flow rate, growth temperature and time, substrate position and location; to the optimum condition produced the best quality at silicon nanostructures. In this work, the best parameter to produce silicon nanostructures is system ramping up 1000°C at 20°C/min heating rate, N2 flow at 100ml/min; silicon needle-like one dimensional silicon nanostructures growth on vertically-positioned substrate located at 12cm from source material for 1 hour growth time. The effects of these parameters on the structures and physical of nanostructures were characterized by field emission scanning electron microscope and x-ray diffraction.
    Matched MeSH terms: Nanostructures
  10. Fulltext Unique wing scale photonics of male Rajah Brooke's birdwing butterflies
    Wilts BD, Giraldo MA, Stavenga DG
    Front. Zool., 2016;13:36.
    PMID: 27525030 DOI: 10.1186/s12983-016-0168-7
    BACKGROUND: Ultrastructures in butterfly wing scales can take many shapes, resulting in the often striking coloration of many butterflies due to interference of light. The plethora of coloration mechanisms is dazzling, but often only single mechanisms are described for specific animals.

    RESULTS: We have here investigated the male Rajah Brooke's birdwing, Trogonoptera brookiana, a large butterfly from Malaysia, which is marked by striking, colorful wing patterns. The dorsal side is decorated with large, iridescent green patterning, while the ventral side of the wings is primarily brown-black with small white, blue and green patches on the hindwings. Dense arrays of red hairs, creating a distinct collar as well as contrasting areas ventrally around the thorax, enhance the butterfly's beauty. The remarkable coloration is realized by a diverse number of intricate and complicated nanostructures in the hairs as well as the wing scales. The red collar hairs contain a broad-band absorbing pigment as well as UV-reflecting multilayers resembling the photonic structures of Morpho butterflies; the white wing patches consist of scales with prominent thin film reflectors; the blue patches have scales with ridge multilayers and these scales also have centrally concentrated melanin. The green wing areas consist of strongly curved scales, which possess a uniquely arranged photonic structure consisting of multilayers and melanin baffles that produces highly directional reflections.

    CONCLUSION: Rajah Brooke's birdwing employs a variety of structural and pigmentary coloration mechanisms to achieve its stunning optical appearance. The intriguing usage of order and disorder in related photonic structures in the butterfly wing scales may inspire novel optical materials as well as investigations into the development of these nanostructures in vivo.

    Matched MeSH terms: Nanostructures
  11. Fulltext Electrochemically synthesized si nanowire arrays and thermoelectric nanostructures
    Ng, Inn Khuan, Kok, Kuan Ying, Nur Ubaidah Saidin, Choo, Thye Foo
    Journal of Nuclear and Related Technologies, 2012;2012(2):34-40.
    MyJurnal
    Thermoelectric nanostructures hold great promise for capturing and directly converting into electricity some vast amount of low-grade waste heats now being lost to the environment (e.g. from nuclear power plant, fossil fuel burning, automotives and household appliances). In this study, large-area vertically-aligned silicon nanowire (SiNW) arrays were synthesized in an aqueous solution containing AgN•i and HF on p-type Si (100) substrate by self-selective electroless etching process. The etching conditions were systematically varied in order to achieve different stages of nanowire formation. Diameters of the SiNWs obtained varied from approximately 50 to 200 nm and their lengths ranged from several to a few tens of um. Te/Bi2Tex.Si thermoelectric core-shell nanostructures were subsequently obtained via galvanic displacement of SiNWs in acidic HF electrolytes containing HTe02+ and 139' /HTe02+ ions. The reactions were basically a nano-electrochemical process due to the difference in redox potentials between the materials. The surface-modified SiNWs of core-shell structures had roughened surface morphologies and, therefore, higher surface-to-bulk ratios compared to unmodified SiNWs. They have potential applications in sensors, photovoltaic and thermoelectric nanodevices. Growth study on the SiNWs and core-shell nanostructures produced is presented using various microscopy, diffraction and probe-based techniques for microstructural, morphological and chemical characterizations.
    Matched MeSH terms: Nanostructures
  12. Fulltext Characterization of silicon nanowires prepared by thermal evaporation using AuPd catalyst
    Mohd. Azam Mohd. Adnan, Cheong, K.Y., Hutagalung, Sabar D.
    Journal of Nuclear and Related Technologies, 2009;2009(1):87-94.
    MyJurnal
    Silicon nanowires were synthesized on Si substrates (111) via thermal evaporation using AuPd thin layer catalyst. Pre cleaned of Si wafer was used as a substrate to assemble the nanostructure products. In this work, the effect of growth temperature that ranging from 800 to 1000°C on the formation of silicon nanowires studied extensively. X-ray diffraction and field emission scanning electron microscope were employed to characterize the structures and morphology of nanowires. Vertical aligned silicon nanowires have been successfully grown on Si substrates at 900 and 1000°C. At 1100°C, the high aspect ratio of silicon nanowires can be produced but the formation density is low. The presence of AuPd catalyst on the tip of nanowires, it is expected that VLS is the most suitable to explain the growth mechanism of obtained SiNWs. The crystalline structure of SiNWs was proved by XRD data.
    Matched MeSH terms: Nanostructures
  13. An insight into nanocellulose as soft condensed matter: Challenge and future prospective toward environmental sustainability
    Tan K, Heo S, Foo M, Chew IM, Yoo C
    Sci Total Environ, 2019 Feb 10;650(Pt 1):1309-1326.
    PMID: 30308818 DOI: 10.1016/j.scitotenv.2018.08.402
    Nanocellulose, a structural polysaccharide that has caught tremendous interests nowadays due to its renewability, inherent biocompatibility and biodegradability, abundance in resource, and environmental friendly nature. They are promising green nanomaterials derived from cellulosic biomass that can be disintegrated into cellulose nanofibrils (CNF) or cellulose nanocrystals (CNC), relying on their sensitivity to hydrolysis at the axial spacing of disordered domains. Owing to their unique mesoscopic characteristics at nanoscale, nanocellulose has been widely researched and incorporated as a reinforcement material in composite materials. The world has been consuming the natural resources at a much higher speed than the environment could regenerate. Today, as an uprising candidate in soft condensed matter physics, a growing interest was received owing to its unique self-assembly behaviour and quantum size effect in the formation of three-dimensional nanostructured material, could be utilised to address an increasing concern over global warming and environmental conservation. In spite of an emerging pool of knowledge on the nanocellulose downstream application, that was lacking of cross-disciplinary study of its role as a soft condensed matter for food, water and energy applications toward environmental sustainability. Here we aim to provide an insight for the latest development of cellulose nanotechnology arises from its fascinating physical and chemical characteristic for the interest of different technology holders.
    Matched MeSH terms: Nanostructures
  14. Pyrus pyrifolia fruit peel as sustainable source for spherical and porous network based nanocellulose synthesis via one-pot hydrolysis system
    Chen YW, Hasanulbasori MA, Chiat PF, Lee HV
    Int J Biol Macromol, 2019 Feb 15;123:1305-1319.
    PMID: 30292586 DOI: 10.1016/j.ijbiomac.2018.10.013
    In the present study, we attempted revalorization of pear (Pyrus pyrifolia L.) peel residue into high value-added nanomaterials. A green and facile one-pot isolation procedure was designed to simplify the isolation process of nanocellulose directly from pear peel residue. The one-pot approach employed in this work is interesting as the reaction involved less harmful chemicals usage and non-multiple steps. The reaction was carried out by adding hydrogen peroxide as an oxidant and chromium (III) nitrate as catalyst in the acidic medium under mild process conditions. FTIR spectroscopy proved that the pear peel derived nanocellulose was purely cellulose phases without the presence of non-cellulosic layer. XRD study indicated that the isolated nanocellulose possessed of cellulose I polymorph with high crystallinity index of 85.7%. FESEM analysis clearly revealed that the considerable size reduction during one-pot process. Remarkably, TEM analysis revealed that the isolated nanocellulose consisted of network-liked nature and spherical shaped morphologies with high aspect ratio of 24.6. TGA showed nanocellulose has lower thermal stability compared to pear peel residue. This study provided a cost-effective method and straightforward one-pot process for fabrication of nanocellulose from pear peel residue. This is the first investigation on the nanocellulose extraction from pear fruit.
    Matched MeSH terms: Nanostructures
  15. Sono-nano chemistry: A new era of synthesising polyhydroxylated carbon nanomaterials with hydroxyl groups and their industrial aspects
    Afreen S, Muthoosamy K, Manickam S
    Ultrason Sonochem, 2019 Mar;51:451-461.
    PMID: 30224290 DOI: 10.1016/j.ultsonch.2018.07.015
    The main objective of this review is to derive the salient features of previously developed ultrasound-assisted methods for hydroxylating graphene and Buckminsterfullerene (C60). The pros and cons associated to ultrasound-assisted synthesis of hydroxy-carbon nanomaterials in designing the strategical methods for the industrial bulk production are also discussed. A guideline on the statistical methods has also been considered to further provide the scopes towards the application of the previously reported methods. Irrespective of many useful methods that have been developed in order to functionalize C60 and graphene by diverse oxygenated functional groups e.g. epoxide, hydroxyl, carboxyl as well as metal/metal oxide via a combination of organic chemistry and sonochemistry, there is no report dealing exclusively on the application of ultrasonic cavitation particularly to synthesising polyhydroxylated carbon nanomaterials. On this context, this review emphasizes in investigating the critical aspects of sono-nanochemistry and the statistical approaches to optimize the variables in the sonochemical process towards a large-scale synthesis of polyhydroxylated graphene and C60.
    Matched MeSH terms: Nanostructures
  16. Fulltext Enhancement of Viscoelastic and Electrical Properties of Magnetorheological Elastomers with Nanosized Ni-Mg Cobalt-Ferrites as Fillers
    Abdul Aziz SA, Mazlan SA, Ubaidillah U, Shabdin MK, Yunus NA, Nordin NA, et al.
    Materials (Basel), 2019 Oct 28;12(21).
    PMID: 31661837 DOI: 10.3390/ma12213531
    Carbon-based particles, such as graphite and graphene, have been widely used as a filler in magnetorheological elastomer (MRE) fabrication in order to obtain electrical properties of the material. However, these kinds of fillers normally require a very high concentration of particles to enhance the conductivity property. Therefore, in this study, the nanosized Ni-Mg cobalt ferrite is introduced as a filler to soften MRE and, at the same time, improve magnetic, rheological, and conductivity properties. Three types of MRE samples without and with different compositions of Mg, namely Co0.5Ni0.2Mg0.3Fe2O4 (A1) and Co0.5Ni0.1Mg0.4Fe2O4 (A2), are fabricated. The characterization related to the micrograph, magnetic, and rheological properties of the MRE samples are analyzed using scanning electron microscopy (SEM), vibrating sample magnetometer (VSM), and the rheometer. Meanwhile, the effect of the nanosized Ni-Mg cobalt ferrites on the electrical resistance property is investigated and compared with the different Mg compositions. It is shown that the storage modulus of the MRE sample with the nanosized Ni-Mg cobalt ferrites is 43% higher than that of the MRE sample without the nanomaterials. In addition, it is demonstrated that MREs with the nanosized Ni-Mg cobalt ferrites exhibit relatively low electrical resistance at the on-state as compared to the off-state condition, because MRE with a higher Mg composition shows lower electrical resistance when higher current flow occurs through the materials. This salient property of the proposed MRE can be effectively and potentially used as an actuator to control the viscoelastic property of the magnetic field or sensors to measure the strain of the flexible structures by the electrical resistance signal.
    Matched MeSH terms: Nanostructures
  17. Comparison between Nucleate Pool Boiling Heat Transfer of Graphene Nanoplatelet- and Carbon Nanotube- Based Aqueous Nanofluids
    Akbari A, Mohammadian E, Alavi Fazel SA, Shanbedi M, Bahreini M, Heidari M, et al.
    ACS Omega, 2019 Nov 19;4(21):19183-19192.
    PMID: 31763542 DOI: 10.1021/acsomega.9b02474
    An increase of nucleate pool boiling with the use of different fluid properties has received much attention. In particular, the presence of nanostructures in fluids to enhance boiling was given special consideration. This study compares the effects of graphene nanoplatelet (GNP), functionalized GNP with polyethylene glycol (PEG), and multiwalled carbon nanotube (CNT) nanofluids on the pool boiling heat transfer coefficient and the critical heat flux (CHF). Our findings showed that at the same concentration, CHF for functionalized GNP with PEG (GNP-PEG)/deionized water (DW) nanofluids was higher in comparison with GNP- and CNT-based nanofluids. The CHF of the GNP/DW nanofluids was also higher than that of CNT/DW nanofluids. The CHF of GNP-PEG was 72% greater than that of DW at the concentration of 0.1 wt %. There is good agreement between measured critical heat fluxes and the Kandlikar correlation. In addition, the current results proved that the GNP-PEG/DW nanofluids are highly stable over 3 months at a concentration of 0.1 wt %.
    Matched MeSH terms: Nanostructures
  18. Nanoscale patterning by AFM lithography and its application on the fabrication of silicon nanowire devices
    Hutagalung SD, Kam CL, Darsono T
    Sains Malaysiana, 2014;43:267-272.
    Many techniques have been applied to fabricate nanostructures via top-down approach such as electron beam lithography. However, most of the techniques are very complicated and involves many process steps, high cost operation as well as the use of hazardous chemicals. Meanwhile, atomic force microscopy (AFM) lithography is a simple technique which is considered maskless and involves only an average cost and less complexity. In AFM lithography, the movement of a probe tip can be controlled to create nanoscale patterns on sample surface. For silicon nanowire (SiNW) fabrication, a conductive tip was operated in non-contact AFM mode to grow nanoscale oxide patterns on silicon-on-insulator (SOI) wafer surface based on local anodic oxidation (LAO) mechanism. The patterned structure was etched through two steps of wet etching processes. First, the TMAH was used as the etchant solution for Si removing. In the second step, diluted HF was used to remove oxide mask in order to produce a completed SiNW based devices. A SiNW based device which is formed by a nanowire channel, source and drain pads with lateral gate structures can be fabricated by well controlling the lithography process (applied tip voltage and writing speed) as well as the etching processes.
    Matched MeSH terms: Nanostructures
  19. Adsorption mechanism of hexavalent chromium onto layered double hydroxides-based adsorbents: A systematic in-depth review
    Tran HN, Nguyen DT, Le GT, Tomul F, Lima EC, Woo SH, et al.
    J Hazard Mater, 2019 07 05;373:258-270.
    PMID: 30925385 DOI: 10.1016/j.jhazmat.2019.03.018
    An attempt has been made in this review to provide some insights into the possible adsorption mechanisms of hexavalent chromium onto layered double hydroxides-based adsorbents by critically examining the past and present literature. Layered double hydroxides (LDH) nanomaterials are typical dual-electronic adsorbents because they exhibit positively charged external surfaces and abundant interlayer anions. A high positive zeta potential value indicates that LDH has a high affinity to Cr(VI) anions in solution through electrostatic attraction. The host interlayer anions (i.e., Cl-, NO3-, SO42-, and CO32-) provide a high anion exchange capacity (53-520 meq/100 g) which is expected to have an excellent exchangeable capacity to Cr(VI) oxyanions in water. Regarding the adsorption-coupled reduction mechanism, when Cr(VI) anions make contact with the electron-donor groups in the LDH, they are partly reduced to Cr(III) cations. The reduced Cr(III) cations are then adsorbed by LDH via numerous interactions, such as isomorphic substitution and complexation. Nonetheless, the adsorption-coupled reduction mechanism is greatly dependent on: (1) the nature of divalent and trivalent salts utilized in LDH preparation, and the types of interlayer anions (i.e., guest intercalated organic anions), and (3) the adsorption experiment conditions. The low Brunauer-Emmett-Teller specific surface area of LDH (1.80-179 m2/g) suggests that pore filling played an insignificant role in Cr(VI) adsorption. The Langmuir maximum adsorption capacity of LDH (Qomax) toward Cr(VI) was significantly affected by the natures of used inorganic salts and synthetic methods of LDH. The Qomax values range from 16.3 mg/g to 726 mg/g. Almost all adsorption processes of Cr(VI) by LDH-based adsorbent occur spontaneously (ΔG° <0) and endothermically (ΔH° >0) and increase the randomness (ΔS° >0) in the system. Thus, LDH has much potential as a promising material that can effectively remove anion pollutants, especially Cr(VI) anions in industrial wastewater.
    Matched MeSH terms: Nanostructures
  20. Fulltext Enhancing Morphology and Separation Performance of Polyamide 6,6 Membranes By Minimal Incorporation of Silver Decorated Graphene Oxide Nanoparticles
    Mahmoudi E, Ng LY, Ang WL, Chung YT, Rohani R, Mohammad AW
    Sci Rep, 2019 02 04;9(1):1216.
    PMID: 30718690 DOI: 10.1038/s41598-018-38060-x
    Nanomaterials can be incorporated in the synthesis of membrane to obtain mixed-matrix membrane with marked improvement in properties and performance. However, stability and dispersion of the nanomaterials in the membrane matrix, as well as the need to use high ratio of nanomaterials for obvious improvement of membrane properties, remain a major hurdle for commercialization. Hence, this study aims to investigate the improvement of polyamide 6,6 membrane properties with the incorporation of silver nanoparticles decorated on graphene oxide (Ag-GO) nanoplates and at the same time focus is given to the issues above. Graphene oxide nanoplates were synthesized using the modified Hummers' method and decorated with silver before embedded into the polyamide 6,6 matrix. Physicochemical characterizations were conducted on both nanoplates and the mixed-matrix Ag-GO polyamide 6,6 membrane. The issues of Ag agglomeration and leaching were not observed, which could be attributed to the decoration of Ag on GO that helped to disperse the nanomaterials and provided a better anchor point for the attachment of Ag nanoparticles. The synthesized membrane showed marked improvement regarding flux (135% increment) and antifouling (40% lower irreversible fouling), which could be ascribed to the more negative charge of membrane surface (-14 ± 6 to -31 ± 3.8 mV) and hydrophilicity (46% enhancement) of the membranes. With minimal embedment of Ag nanoparticles, the membrane showed superior antibacterial property where the E. coli bacteria could not form a single colony on the membrane surface. Overall, the decoration of Ag on GO nanoplates could be a promising approach to resolve the agglomeration and leaching issues as well as reduce the amount of precious Ag in the synthesis of Ag-GO polyamide 6,6 membrane.
    Matched MeSH terms: Nanostructures
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