Displaying publications 261 - 280 of 1298 in total

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  1. Structural properties of zinc oxide thin films deposited on various substrates
    Ching C, Om P, Ng S, Hassan Z, Abu Hassan H, Abdullah M
    Sains Malaysiana, 2014;43:923-927.
    In this work, the structural properties of radio frequency sputtering-grown zinc oxide (ZnO) thin films on sapphire (Al203), gallium arsenide (GaAs) and n-type silicon (Si) substrates were characterized. Scanning electron microscopy was employed to study the surface morphology of the samples. X-ray diffraction (xRD) measurements were also performed to obtain the structural information of the samples. The xRD results showed that the ZnO layers grown on different substrates have similar lattice constant (c) values, which were used to calculate the strain percentages of the ZnO thin films. The surface morphologies of the ZnO thin films indicated the formation of a granular surface when ZnO is deposited on n-type Si(100) and Si( 111 ) substrates. Meanwhile, a leaf-like surface is obtained when ZnO is deposited on GaAs and Al203 substrates. The results showed that the ZnO thin film grown on n-type Si(100) has the best quality among all the samples.
    Matched MeSH terms: Microscopy, Electron, Scanning
  2. Characterization of the feedstock properties of metal injection-molded WC-Co with palm stearin binder system
    Sri Yulis M. Amin, Norhamidi Muhamad, Khairur Rijal Jamaludin, Fayyaz A, Heng SY
    Sains Malaysiana, 2014;43:123-128.
    Feedstock preparation, as well as its characterization, is crucial in the production of highly sintered parts with minimal defect. The hard metal powder - particularly, cemented carbide (wc-co) used in this study was investigated both physically and thermally to determine its properties before the mixing and injection molding stage. Several analyses were conducted, such as scanning electron microscopy, energy dispersive X-ray diffraction, pycnometer density, critical powder volume percentage (cPvP), as well as thermal tests, such as thermogravimetric analysis and differential scanning calorimetry. On the basis of the CPVP value, the feedstock, consisting of wc-co powder, was mixed with 60% palm stearin and 40% polyethylene at an optimal powder loading, within 2 to 5% lower than the CPVP value. The CPVP spotted value was 65%. The feedstock optimal value at 61% showed good rheological properties (pseudoplastic behavior) with an n value lower than 1, considerably low activation energy and high moldability index. These preliminary properties of the feedstock serve as a benchmark in designing the schedule for the next whole steps (i.e. injection, debinding and sintering processes).
    Matched MeSH terms: Microscopy, Electron, Scanning
  3. Experimental study on permeability stress sensitivity in tight sandstone oil reservoirs
    Xiaofeng Tian, Linsong Cheng, Wenqi Zhao, Yiqun Yan, Xiaohui He, Qiang Guo
    Sains Malaysiana, 2015;44:719-725.
    In this paper, seven permeability stress sensitivity experiments were conducted to show the features of permeability stress
    sensitivity. The cores in the experiments were taken from the tight sandstone oil reservoir in Ordos Basin. Then advanced
    technologies, such as casting thin section, scanning electron microscope and rate-controlled mercury penetration, were
    applied to explain the mechanism of permeability stress sensitivity in tight oil reservoirs. The results indicated that
    the permeability reduction and recovery in gas permeability stress sensitivity increases as the permeability decreases.
    This was resulted from the maximal throat radius. The permeability reduction in liquid permeability stress sensitivity
    increases at first and then decreases as the permeability decreases. The permeability recovery decreases to zero as the
    permeability decreases. Additionally, the differences between gas and liquid permeability stress sensitivity become greater
    as the permeability decreases. These were resulted from the effect of the critical throat radius. This paper corrects the
    mistakes about the stress sensitivity in tight oil reservoirs from gas permeability stress sensitivity experiments which is
    significant to the development of tight sandstone oil reservoirs.
    Matched MeSH terms: Microscopy, Electron, Scanning
  4. Taxonomic significance of cypsela morphology in tribe Cichoreae (Asteraceae) using light microscopy and scanning electron microscopy
    Ayaz S, Ahmad M, Zafar M, Ali MI, Sultana S, Mustafa MRU, et al.
    Microsc Res Tech, 2020 Mar;83(3):239-248.
    PMID: 31713962 DOI: 10.1002/jemt.23407
    The current study deals with the detailed morphology investigation of eight Cypsela species belonging to tribe Cichoreae. The different Cypsela types were described, explained, compared, and their taxonomic significance is discussed in detail. Light microscopy (LM) and scanning electron microscopy (SEM) have been used to highlight quantitative and qualitative characters of underestudied species. Cypsela exhibit great diversity in macro and micromorphological features such as shape, color, length, width, anticlinal and periclinal wall patterns, surface patterns, epicuticular projections. Majority of Cypsela species were brownish in color and their size ranges from 2.16 to 3.98 mm in length and 1.16 to 0.82 mm in breadth. A great diversity in Cypsela shapes like oblanceolate to obovate, obovoid to cylindrical, obvate, narrowly lanceolate were observed. Most of the platelets having epicuticular projections were observed. The surface pattern on the cypsela surface varied from rugose papillate, verrucose papillate, and striated. On the basis of considerable variations observed, the present study can assist as useful constraints at various taxonomic levels. The aim of the present study is to provide a comprehensive description of the Cypsela morphology and to determine the extent to which these micro morphological data can be used as a taxonomic character to delineate various taxa belonging to the tribe Cichoreae.
    Matched MeSH terms: Microscopy, Electron, Scanning
  5. Fulltext Amino Anthraquinone: Synthesis, Characterization, and Its Application as an Active Material in Environmental Sensors
    Ali S, Tahir M, Mehboob N, Wahab F, J Langford S, Mohd Said S, et al.
    Materials (Basel), 2020 Feb 21;13(4).
    PMID: 32098037 DOI: 10.3390/ma13040960
    This work reports synthesis, thin film characterizations, and study of an organic semiconductor 2-aminoanthraquinone (AAq) for humidity and temperature sensing applications. The morphological and phase studies of AAq thin films are carried out by scanning electron microscope (SEM), atomic force microscope (AFM), and X-ray diffraction (XRD) analysis. To study the sensing properties of AAq, a surface type Au/AAq/Au sensor is fabricated by thermally depositing a 60 nm layer of AAq at a pressure of ~10-5 mbar on a pre-patterned gold (Au) electrodes with inter-electrode gap of 45 µm. To measure sensing capability of the Au/AAq/Au device, the variations in its capacitance and resistance are studied as a function of humidity and temperature. The Au/AAq/Au device measures and exhibits a linear change in capacitance and resistance when relative humidity (%RH) and temperature are varied. The AAq is a hydrophobic material which makes it one of the best candidates to be used as an active material in humidity sensors; on the other hand, its high melting point (575 K) is another appealing property that enables it for its potential applications in temperature sensors.
    Matched MeSH terms: Microscopy, Electron, Scanning
  6. Fulltext Scanning Electron Microscopy Study of Retrieved Implants Suggests a Ratcheting Mechanism Behind Medial Migration in Cephalomedullary Nailing of Hip Fractures
    Law GW, Koh J, Yew A, Howe TS
    Malays Orthop J, 2020 Mar;14(1):7-17.
    PMID: 32296476 DOI: 10.5704/MOJ.2003.002
    Introduction: Medial migration is the paradoxical migration of the femoral neck element (FNE) superomedially against gravity with respect to the intramedullary component of the cephalomedullary device, increasingly seen in the management of pertrochanteric hip fractures with the intramedullary nail. We postulate that the peculiar anti-gravity movement of the FNE in the medial migration phenomenon stems from a ratcheting mechanism at the intramedullary nail-FNE interface, which should inadvertently produce unique wear patterns on the FNE that can be seen with high-powered microscopy. By examining the wear patterns on retrieved implants from patients with medial migration, our study aims to draw clinical correlations to the ratcheting mechanism hypothesis.

    Material and Methods: Four FNEs were retrieved from revision surgeries of four patients with prior intramedullary nail fixation of their pertrochanteric hip fractures complicated by femoral head perforation. The FNEs were divided into two groups based on whether or not there was radiographic evidence of medial migration prior to the revisions. Wear patterns on the FNEs were then assessed using both scanning electron microscopy and light microscopy.

    Results: Repetitive, linearly-arranged, regularly-spaced, unique transverse scratch marks were found only in the group with medial migration, corresponding to the specific segment of the FNE that passed through the intramedullary component of the PFNA during medial migration. These scratch marks were absent in the group without medial migration.

    Conclusion: Our findings are in support of a ratcheting mechanism behind the medial migration phenomenon with repetitive toggling at the intramedullary nail-FNE interface and progressive propagation of the FNE against gravity.

    Matched MeSH terms: Microscopy, Electron, Scanning
  7. Synthesis of zinc selenide/graphene oxide composite via direct and indirect hydrothermal method
    Kee LH, Ying Chyi JL, Zainal Abidin Talib, Mohammad Shuhazlly Mamat, Hong Ngee JL, Fakhrurrazi Ashari, et al.
    Sains Malaysiana, 2016;45:1201-1206.
    Zinc selenide/graphene oxide (ZnSe/GO) composite is synthesized using hydrothermal method. Two different methods
    such as direct and indirect route have been investigated to form the ZnSe/GO composite. In this research, the graphene
    oxide used was in sheet and liquid form. The synthesized composite was then characterized using X-ray diffraction (XRD)
    for phase identification, field emission scanning electron microscopy (FESEM) for morphology analysis and ultravioletvisible
    spectroscopy (UV-Vis) for optical properties. ZnSe/GO composite showed absorption peak ranging from 460 to
    480 nm with the optical band gap obtained through Tauc equation. The optical band gap of the ZnSe/GO composite has
    been tuned down to a smaller value as compared to the bulk ZnSe compound. The optical band gap has been reduced
    to around 2.53 eV when liquid graphene oxide was used while around 2.23 to 2.32 eV when graphene oxide sheet was
    used. The purity of ZnSe/GO composite synthesis via indirect hydrothermal method is higher than those synthesized via
    direct hydrothermal method. The type of graphene oxide will affect the morphology of the composite where the ZnSe
    compound was either wrapped by tiny thorn-like substance or graphene oxide layer.
    Matched MeSH terms: Microscopy, Electron, Scanning
  8. Influence of hydrochloric acid volume on the growth of titanium dioxide (TiO2) nanostructures by hydrothermal method
    Noor Kamalia Abd Hamed, Noor Sakinah Khalid, Fatin Izyani Mohd Fazli, Muhammad Luqman Mohd Napi, Nafarizal Nayan, Mohd Khairul Ahmad
    Sains Malaysiana, 2016;45:1669-1673.
    Titanium dioxide (TiO2
    ) with various morphologies has been successfully synthesized by a simple hydrothermal method
    at 150o
    C for 10 h using titanium butoxide (TBOT) as a precursor, deionized (DI) water and hydrochloric acid (HCl) on
    a fluorine-doped tin oxide (FTO) substrate. The influences of HCl volume on structural and morphological properties
    of TiO2
    have been studied using x-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM),
    respectively. The result showed that several morphologies such as microsphere, microrods, nanorods and nanoflowers
    were obtained by varying the volume of hydrochloric acid. The crystallinity of titanium dioxide enhanced with the
    increasing of hydrochloric acid volume.
    Matched MeSH terms: Microscopy, Electron, Scanning
  9. Fecl3-activated carbon developed from coconut leaves: characterization and application for methylene blue removal
    Ali H. Jawad, Mohd Azlan Bin Mohd Ishak, Nur Nasulhah Kasim, Ramlah Abd Rashid
    Sains Malaysiana, 2018;47:603-610.
    In this study, coconut leaves were used as a starting material for the production of activated carbon by thermal
    carbonization using FeCl3
    -activation method. The characterization of coconut leaves-FeCl3
    activated carbon (FAC) were
    evaluated by bulk density, ash content, moisture content, point-of-zero charge (pHpzc) analysis, iodine test, scanning
    electron microscopy (SEM), Fourier transform infrared (FTIR) and elemental (CHNS-O) analysis. The effect of the adsorbent
    dosage (0.02-0.25 g), initial pH (3-11), initial dye concentrations (30-350 mg/L) and contact time (1-180 min) on the
    adsorption of the methylene blue (MB) at 303 K was performed via batch experiments. The Pseudo-Second Order (PSO)
    describes the kinetic model well whereas the Langmuir isotherm proved that adsorption behavior at equilibrium with
    maximum adsorption capacity (qmax) of 66.00 mg/g.
    Matched MeSH terms: Microscopy, Electron, Scanning
  10. Facile synthesis of AgCl/BiYO3 composite for efficient photodegradation of RO16 under UV and visible light irradiation
    Sirimahachai R, Harome H, Wongnawa S
    Sains Malaysiana, 2017;46:1393-1399.
    AgCl/BiYO3
    composite was successfully synthesized via the aqueous precipitation method followed by calcination. The
    varied amount of AgCl (10, 20 and 30%) was mixed into BiYO3
    via sonochemical-assisted method. The structures and
    morphologies of the as-prepared AgCl/BiYO3
    composite were characterized by x-ray diffraction (XRD), scanning electron
    microscopy (SEM) and UV-vis diffused reflectance spectroscopy (UV-vis DRS). The optical absorption spectrum of AgCl/
    BiYO3
    composite showed strong absorption in visible region. The photocatalytic activity of AgCl/BiYO3
    composite was
    evaluated by the photodegradation of reactive orange16 (RO16), which was selected to represent the dye pollutants,
    under UV and visible light irradiation. The results indicated that 20% AgCl/BiYO3 photocatalyst was the most capable
    photocatalyst in this series in the degradation of RO16 under both UV and visible light illumination within 1 h. Moreover,
    the mechanism of photocatalytic degradation of AgCl/BiYO3
    was elucidated using three types of free radical scavengers.
    The significant enhancement was attributed to the formation of AgCl/BiYO3
    heterojunction resulting in the low electronhole
    pair recombination rate.
    Matched MeSH terms: Microscopy, Electron, Scanning
  11. Fulltext Surface Energy Mapping of Modified Silica Using IGC Technique at Finite Dilution
    Ngeow YW, Williams DR, Chapman AV, Heng JYY
    ACS Omega, 2020 May 12;5(18):10266-10275.
    PMID: 32426583 DOI: 10.1021/acsomega.9b03920
    The reinforcing silica filler, which can be more than 40% of an elastomer composite, plays a key role to achieve the desired mechanical properties in elastomer vulcanizates. However, the highly hydrophilic nature of silica surface causes silica particle aggregation. It remained a challenge for many tire manufacturers when using silica-filled elastomer compounds. Here, the silica surface energy changes when the surface is modified with coupling or noncoupling silanes; coupling silanes can covalently bond the silica to the elastomers. The surface energy of silica was determined using inverse gas chromatography (IGC) at finite dilution (FD-IGC) and found to be reduced by up to 50% when the silica surface was silanized. The spatial distribution of silica aggregates within the tire matrix is determined by transmission electron microscopy (TEM) and a direct correlation between aggregate size (silica microdispersion) and work of cohesion from IGC is reported, highlighting surface energy and work of cohesion being excellent indicators of the degree of dispersion of silica aggregates.
    Matched MeSH terms: Microscopy, Electron, Transmission
  12. Localization of burn mark under an abnormal topography on MOSFET chip surface using liquid crystal and emission microscopy tools
    Lau CK, Sim KS, Tso CP
    Scanning, 2011 Jan-Feb;33(1):13-20.
    PMID: 21462221 DOI: 10.1002/sca.20216
    This article focuses on the localization of burn mark in MOSFET and the scanning electron microscope (SEM) inspection on the defect location. When a suspect abnormal topography is shown on the die surface, further methods to pin-point the defect location is necessary. Fault localization analysis becomes important because an abnormal spot on the chip surface may and may not have a defect underneath it. The chip surface topography can change due to the catastrophic damage occurred at layers under the chip surface, but it could also be due to inconsistency during metal deposition in the wafer fabrication process. Two localization techniques, liquid crystal thermography and emission microscopy, were performed to confirm that the abnormal topography spot is the actual defect location. The tiny burn mark was surfaced by performing a surface decoration at the defect location using hot hydrochloric acid. SEM imaging, which has the high magnification and three-dimensional capabilities, was used to capture the images of the burn mark.
    Matched MeSH terms: Microscopy, Electron, Scanning
  13. Size-Controlled and Optical Properties of Platinum Nanoparticles by Gamma Radiolytic Synthesis
    Gharibshahi E, Saion E, Ashraf A, Gharibshahi L
    Appl Radiat Isot, 2017 Dec;130:211-217.
    PMID: 29028581 DOI: 10.1016/j.apradiso.2017.09.012
    Gamma radiolytic synthesis was used to produce size-controlled spherical platinum nanoparticles from an aqueous solution containing platinum tetraammine and polyvinyl pyrrolidone. The structural characterizations were performed using X-ray diffraction, and transmission electron microscopy. The transmission electron microscopy was used to determine the average particle diameter, which decreased from 4.4nm at 80kGy to 2.8nm at 120kGy. The UV-visible absorption spectrum was measured and found that platinum nanoparticles exhibit two steady absorption maxima in UV regions due to plasmonic excitation of conduction electrons, which blue shifted to lower wavelengths with a decrease in particle size. We consider the conduction electrons of platinum nanoparticles to follow Thomas-Fermi-Dirac-Weizsacker atomic model that they are not entirely free but weakly bounded to particles at lower-energy states {n = 5, l = 2 or 5d} and {n = 6, l = 0 or 6s}, which upon receiving UV photon energy the electrons make intra-band quantum excitations to higher-energy states allowed by the principles of quantum number that results the absorption maxima. We found an excellent agreement between the experimental and theoretical results, which suggest that the optical absorption of metal nanoparticles could be fundamentally described by a quantum mechanical interpretation, which could be more relevant to photo-catalysis and heterogeneous catalysis.
    Matched MeSH terms: Microscopy, Electron, Transmission
  14. Fulltext Preparation and Thermal Characterization of Annealed Gold Coated Porous Silicon
    Behzad K, Mat Yunus WM, Talib ZA, Zakaria A, Bahrami A
    Materials (Basel), 2012 Jan 16;5(1):157-168.
    PMID: 28817037 DOI: 10.3390/ma5010157
    Porous silicon (PSi) layers were formed on a p-type Si wafer. Six samples were anodised electrically with a 30 mA/cm² fixed current density for different etching times. The samples were coated with a 50-60 nm gold layer and annealed at different temperatures under Ar flow. The morphology of the layers, before and after annealing, formed by this method was investigated by scanning electron microscopy (SEM). Photoacoustic spectroscopy (PAS) measurements were carried out to measure the thermal diffusivity (TD) of the PSi and Au/PSi samples. For the Au/PSi samples, the thermal diffusivity was measured before and after annealing to study the effect of annealing. Also to study the aging effect, a comparison was made between freshly annealed samples and samples 30 days after annealing.
    Matched MeSH terms: Microscopy, Electron, Scanning
  15. Fulltext Effect of Starch Loading on the Thermo-Mechanical and Morphological Properties of Polyurethane Composites
    Gaaz TS, Sulong AB, Ansari MNM, Kadhum AAH, Al-Amiery AA, Nassir MH
    Materials (Basel), 2017 Jul 10;10(7).
    PMID: 28773134 DOI: 10.3390/ma10070777
    The advancements in material science and technology have made polyurethane (PU) one of the most important renewable polymers. Enhancing the physio-chemical and mechanical properties of PU has become the theme of this and many other studies. One of these enhancements was carried out by adding starch to PU to form new renewable materials called polyurethane-starch composites (PUS). In this study, PUS composites are prepared by adding starch at 0.5, 1.0, 1.5, and 2.0 wt.% to a PU matrix. The mechanical, thermal, and morphological properties of PU and PUS composites were investigated. Scanning electron microscope (SEM) images of PU and PUS fractured surfaces show cracks and agglomeration in PUS at 1.5 wt.% starch. The thermo-mechanical properties of the PUS composites were improved as starch content increased to 1.5 wt.% and declined by more starch loading. Despite this reduction, the mechanical properties were still better than that of neat PU. The mechanical strength increased as starch content increased to 1.5 wt.%. The tensile, flexural, and impact strengths of the PUS composites were found to be 9.62 MPa, 126.04 MPa, and 12.87 × 10(-3) J/mm², respectively, at 1.5 wt.% starch. Thermal studies showed that the thermal stability and crystallization temperature of the PUS composites increased compared to that of PU. The loss modulus curves showed that neat PU crystallizes at 124 °C and at 127 °C for PUS-0.5 wt.% and rises with increasing loading from 0.5 to 2 wt.%.
    Matched MeSH terms: Microscopy, Electron, Scanning
  16. Fulltext Surface Characteristics and Catalytic Activity of Copper Deposited Porous Silicon Powder
    Halim MYA, Tan WL, Bakar NHHA, Bakar MA
    Materials (Basel), 2014 Dec 04;7(12):7737-7751.
    PMID: 28788272 DOI: 10.3390/ma7127737
    Porous structured silicon or porous silicon (PS) powder was prepared by chemical etching of silicon powder in an etchant solution of HF: HNO₃: H₂O (1:3:5 v/v). An immersion time of 4 min was sufficient for depositing Cu metal from an aqueous solution of CuSO₄ in the presence of HF. Scanning electron microscopy (SEM) analysis revealed that the Cu particles aggregated upon an increase in metal content from 3.3 wt% to 9.8 wt%. H₂-temperature programmed reduction (H₂-TPR) profiles reveal that re-oxidation of the Cu particles occurs after deposition. Furthermore, the profiles denote the existence of various sizes of Cu metal on the PS. The Cu-PS powders show excellent catalytic reduction on the p-nitrophenol regardless of the Cu loadings.
    Matched MeSH terms: Microscopy, Electron, Scanning
  17. Fulltext Interfaces between hexagonal and cubic oxides and their structure alternatives
    Zhou H, Wu L, Wang HQ, Zheng JC, Zhang L, Kisslinger K, et al.
    Nat Commun, 2017 11 14;8(1):1474.
    PMID: 29133800 DOI: 10.1038/s41467-017-01655-5
    Multi-layer structure of functional materials often involves the integration of different crystalline phases. The film growth orientation thus frequently exhibits a transformation, owing to multiple possibilities caused by incompatible in-plane structural symmetry. Nevertheless, the detailed mechanism of the transformation has not yet been fully explored. Here we thoroughly probe the heteroepitaxially grown hexagonal zinc oxide (ZnO) films on cubic (001)-magnesium oxide (MgO) substrates using advanced scanning transition electron microscopy, X-ray diffraction and first principles calculations, revealing two distinct interface models of (001) ZnO/(001) MgO and (100) ZnO/(001) MgO. We have found that the structure alternatives are controlled thermodynamically by the nucleation, while kinetically by the enhanced Zn adsorption and O diffusion upon the phase transformation. This work not only provides a guideline for the interface fabrication with distinct crystalline phases but also shows how polar and non-polar hexagonal ZnO films might be manipulated on the same cubic substrate.
    Matched MeSH terms: Microscopy, Electron, Scanning
  18. Scanning electron microscopy of antennal sensilla of the eight Anopheles species of the Hyrcanus Group (Diptera: Culicidae) in Thailand
    Hempolchom C, Yasanga T, Wijit A, Taai K, Dedkhad W, Srisuka W, et al.
    Parasitol Res, 2017 Jan;116(1):143-153.
    PMID: 27752768
    Antennal sensilla were first investigated in the eight medically and veterinary important Anopheles mosquito species (Anopheles argyropus, Anopheles crawfordi, Anopheles nigerrimus, Anopheles nitidus, Anopheles paraliae (= Anopheles lesteri), Anopheles peditaeniatus, Anopheles pursati, and Anopheles sinensis) of the Hyrcanus Group in Thailand, using scanning electron microscopy (SEM). Four types of sensilla, including sensilla chaetica (large and small), sensilla trichodea (sharp- and blunt-tipped), sensilla basiconica or grooved pegs (types I, II, and III), and sensilla coeloconica (large and small), were observed on the female antennae of the eight species. The greatest number of sensilla found along the flagellum of all the Anopheles species consisted of sensilla trichodea. Grooved pegs type II were not found on the antennae of An. peditaeniatus. Interestingly, clusters of 10-15 grooved pegs type III, with blunt-tipped and unevenly grooved-lengthwise sensilla, and a sunken group of 7-12 grooved pegs type III, with slightly curved and point-tipped sensilla, were found distally on flagellomeres 3-7 of An. argyropus and An. peditaeniatus, respectively. In addition, the key for species identification, based on fine structure and morphometrics of antennal sensilla among the eight species, was constructed and differentiated successfully. However, in order to focus intensively on the exact function of these sensilla, further electrophysiological study is needed in understanding their significant role in mosquito behavior, especially when these insects seek hosts for transmitting pathogens to humans.
    Matched MeSH terms: Microscopy, Electron, Scanning
  19. The True Amphipathic Nature of Graphene Flakes: A Versatile 2D Stabilizer
    Kuziel AW, Milowska KZ, Chau PL, Boncel S, Koziol KK, Yahya N, et al.
    Adv Mater, 2020 Aug;32(34):e2000608.
    PMID: 32672882 DOI: 10.1002/adma.202000608
    The fundamental colloidal properties of pristine graphene flakes remain incompletely understood, with conflicting reports about their chemical character, hindering potential applications that could exploit the extraordinary electronic, thermal, and mechanical properties of graphene. Here, the true amphipathic nature of pristine graphene flakes is demonstrated through wet-chemistry testing, optical microscopy, electron microscopy, and density functional theory, molecular dynamics, and Monte Carlo calculations, and it is shown how this fact paves the way for the formation of ultrastable water/oil emulsions. In contrast to commonly used graphene oxide flakes, pristine graphene flakes possess well-defined hydrophobic and hydrophilic regions: the basal plane and edges, respectively, the interplay of which allows small flakes to be utilized as stabilizers with an amphipathic strength that depends on the edge-to-surface ratio. The interactions between flakes can be also controlled by varying the oil-to-water ratio. In addition, it is predicted that graphene flakes can be efficiently used as a new-generation stabilizer that is active under high pressure, high temperature, and in saline solutions, greatly enhancing the efficiency and functionality of applications based on this material.
    Matched MeSH terms: Microscopy, Electron
  20. Functional Validation of DownRegulated MicroRNAs in HeLa Cells Treated with Polyalthia longifolia Leaf Extract Using Different Microscopic Approaches: A Morphological Alteration-Based Validation
    Shanmugapriya, Vijayarathna S, Sasidharan S
    Microsc Microanal, 2019 10;25(5):1263-1272.
    PMID: 31383043 DOI: 10.1017/S1431927619014776
    Several microscopy methods have been developed to assess the morphological changes in cells in the investigations of the mode of cell death in response to a stimulus. Our recent finding on the treatment of the IC50 concentration (26.67 μg/mL) of Polyalthia longifolia leaf extract indicated the induction of apoptotic cell death via the regulation of miRNA in HeLa cells. Hence, the current study was conducted to validate the function of these downregulated microRNAs in P. longifolia-treated HeLa cells using microscopic approaches. These include scanning electron microscope (SEM), transmission electron microscope (TEM), and acridine orange/propidium iodide (AO/PI)-based fluorescent microscopy techniques by observing the morphological alterations to cells after transfection with mimic miRNA. Interestingly, the morphological changes observed in this study demonstrated the apoptotic hallmarks, for instance, cell blebbing, cell shrinkage, cytoplasmic and nuclear condensation, vacuolization, cytoplasmic extrusion, and the formation of apoptotic bodies, which proved the role of dysregulated miRNAs in apoptotic HeLa cell death after treatment with the P. longifolia leaf extract. Conclusively, the current study proved the crucial role of downregulated miR-484 and miR-221-5p in the induction of apoptotic cell death in P. longifolia-treated HeLa cells using three approaches-SEM, TEM, and AO/PI-based fluorescent microscope.
    Matched MeSH terms: Microscopy, Electron, Scanning/methods; Microscopy, Electron, Transmission/methods
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