Displaying publications 1 - 20 of 85 in total

  1. Rizwan K, Rasool N, Rehman R, Mahmood T, Ayub K, Rasheed T, et al.
    Chem Cent J, 2018 Jul 17;12(1):84.
    PMID: 30019193 DOI: 10.1186/s13065-018-0451-0
    A variety of imine derivatives have been synthesized via Suzuki cross coupling of N-(4-bromophenyl)-1-(3-bromothiophen-2-yl)methanimine with various arylboronic acids in moderate to good yields (58-72%). A wide range of electron donating and withdrawing functional groups were well tolerated in reaction conditions. To explore the structural properties, Density functional theory (DFT) investigations on all synthesized molecules (3a-3i) were performed. Conceptual DFT reactivity descriptors and molecular electrostatic potential analyses were performed by using B3LYP/6-31G(d,p) method to explore the reactivity and reacting sites of all derivatives (3a-3i).
    Matched MeSH terms: Static Electricity
  2. Panicker CY, Varghese HT, Nayak PS, Narayana B, Sarojini BK, Fun HK, et al.
    PMID: 25863456 DOI: 10.1016/j.saa.2015.03.065
    FT-IR spectrum of (2E)-3-(3-nitrophenyl)-1-[4-piperidin-1-yl]prop-2-en-1-one was recorded and analyzed. The vibrational wavenumbers were computed using HF and DFT quantum chemical calculations. The data obtained from wavenumber calculations are used to assign IR bands. Potential energy distribution was done using GAR2PED software. The geometrical parameters of the title compound are in agreement with the XRD results. NBO analysis, HOMO-LUMO, first and second hyperpolarizability and molecular electrostatic potential results are also reported. The possible electrophile attacking sites of the title molecule is identified using MEP surface plot study. Molecular docking results predicted the anti-leishmanic activity for the compound.
    Matched MeSH terms: Static Electricity
  3. Silvarajoo S, Osman UM, Kamarudin KH, Razali MH, Yusoff HM, Bhat IUH, et al.
    Data Brief, 2020 Oct;32:106299.
    PMID: 32984485 DOI: 10.1016/j.dib.2020.106299
    One-pot synthetic method was adopted to prepare three isomers 4-(ortho-fluorophenyl)thiosemi- carbazide), 4-(meta-fluorophenyl)thiosemicarbazide and 4-(para-fluorophenyl)thiosemicarbazide. The products were obtained in ethanolic solution from a reaction between ortho, meta and para derivatives of fluorophenyl isothiocyanate and hydrazine hydrate. This work presents the theoretical Molecular Electrostatic Potential (MEP) and Highest Occupied Molecular Orbital-Lowest Unoccupied Molecular Orbital (HOMO-LUMO) computational data through Gaussview 5.0.9 and Gaussian09 software. Experimental Cole-cole plot for conductivity determination was also illustrated. The present data is important to manipulate the properties of compounds according to the position of a fluorine atom.
    Matched MeSH terms: Static Electricity
  4. Rehman GU, Tahir M, Goh PS, Ismail AF, Samavati A, Zulhairun AK, et al.
    Environ Pollut, 2019 Oct;253:1066-1078.
    PMID: 31434184 DOI: 10.1016/j.envpol.2019.07.013
    In this study, the synthesis of Fe3O4@GO@g-C3N4 ternary nanocomposite for enhanced photocatalytic degradation of phenol has been investigated. The surface modification of Fe3O4 was performed through layer-by-layer electrostatic deposition meanwhile the heterojunction structure of ternary nanocomposite was obtained through sonicated assisted hydrothermal method. The photocatalysts were characterized for their crystallinity, surface morphology, chemical functionalities, and band gap energy. The Fe3O4@GO@g-C3N4 ternary nanocomposite achieved phenol degradation of ∼97%, which was significantly higher than that of Fe3O4@GO (∼75%) and Fe3O4 (∼62%). The enhanced photoactivity was due to the efficient charge carrier separation and desired band structure. The photocatalytic performance was further enhanced with the addition of hydrogen peroxide, in which phenol degradation up to 100% was achieved in 2 h irradiation time. The findings revealed that operating parameters have significant influences on the photocatalytic activities. It was found that lower phenol concentration promoted higher activity. In this study, 0.3 g of Fe3O4@GO@g-C3N4 was found to be the optimized photocatalyst for phenol degradation. At the optimized condition, the reaction rate constant was reported as 6.96 × 10-3 min-1. The ternary photocatalyst showed excellent recyclability in three consecutive cycles, which confirmed the stability of this ternary nanocomposite for degradation applications.
    Matched MeSH terms: Static Electricity
  5. Caracelli I, Zukerman-Schpector J, Schwab RS, da Silva EM, Jotani MM, Tiekink ERT
    Acta Crystallogr E Crystallogr Commun, 2019 Aug 01;75(Pt 8):1232-1238.
    PMID: 31417798 DOI: 10.1107/S2056989019010284
    The di-substituted acetyl-ene residue in the title compound, C11H11NO3, is capped at either end by di-methyl-hydroxy and 4-nitro-benzene groups; the nitro substituent is close to co-planar with the ring to which it is attached [dihedral angle = 9.4 (3)°]. The most prominent feature of the mol-ecular packing is the formation, via hy-droxy-O-H⋯O(hy-droxy) hydrogen bonds, of hexa-meric clusters about a site of symmetry . The aggregates are sustained by 12-membered {⋯OH}6 synthons and have the shape of a flattened chair. The clusters are connected into a three-dimensional architecture by benzene-C-H⋯O(nitro) inter-actions, involving both nitro-O atoms. The aforementioned inter-actions are readily identified in the calculated Hirshfeld surface. Computational chemistry indicates there is a significant energy, primarily electrostatic in nature, associated with the hy-droxy-O-H⋯O(hy-droxy) hydrogen bonds. Dispersion forces are more important in the other identified but, weaker inter-molecular contacts.
    Matched MeSH terms: Static Electricity
  6. Anizaim AH, Zaini MF, Laruna MA, Razak IA, Arshad S
    Acta Crystallogr E Crystallogr Commun, 2019 May 01;75(Pt 5):632-637.
    PMID: 31110801 DOI: 10.1107/S2056989019004912
    In the title compound, C18H12O3S2, synthesized by the Claisen-Schmidt condensation method, the essentially planar chalcone unit adopts an s-cis configuration with respect to the carbonyl group within the ethyl-enic bridge. In the crystal, weak C-H⋯π inter-actions connect the mol-ecules into zigzag chains along the b-axis direction. The mol-ecular structure was optimized geometrically using Density Functional Theory (DFT) calculations at the B3LYP/6-311 G++(d,p) basis set level and compared with the experimental values. Mol-ecular orbital calculations providing electron-density plots of HOMO and LUMO mol-ecular orbitals and mol-ecular electrostatic potentials (MEP) were also computed both with the DFT/B3LYP/6-311 G++(d,p) basis set. The experimental energy gap is 3.18 eV, whereas the theoretical HOMO-LUMO energy gap value is 2.73 eV. Hirshfeld surface analysis was used to further investigate the weak inter-actions present.
    Matched MeSH terms: Static Electricity
  7. Ismail Saad, Razali Ismail, Ima Sulaiman
    Sains Malaysiana, 2008;37:233-237.
    Conventional lateral and vertical n-channel MOS transistors with channel length in the range of 100nm to 50nm have been systematically investigated by means of device simulation. The comparison analysis includes critical parameters that govern device performance. Threshold voltage VT roll-off, leakage current Ioff, drain saturation current IDsat and sub-threshold swing S were analyze and compared between the device. Due to double gate (DG) structure over the side of silicon pillar a better electrostatics potential control of channel is obtained in vertical device shown by an analysis on VT roll-off. A two decade higher of Ioff in planar device is observed with Lg=50nm. A factor of three times larger IDsat is observed for vertical MOSFETs compared to planar device. The sub-threshold swing S remains almost the same when the Lg larger than 80 nm. It increased rapidly when the Lg is scaled down to 50 nm due to the short channel effect SCE. However, the vertical device has a steady increase whereas the planar device has suffered immediate enhance of SCE. The analysis results confirmed that vertical MOSFET with double-gate structure is a potential solution to overcome SCE when scaled the channel length to 50nm and beyond.
    Matched MeSH terms: Static Electricity
  8. Ahmad NF, Komatsu K, Iwasaki T, Watanabe K, Taniguchi T, Mizuta H, et al.
    Sci Rep, 2019 Feb 28;9(1):3031.
    PMID: 30816251 DOI: 10.1038/s41598-019-39909-5
    We report on the observation of quantum transport and interference in a graphene device that is attached with a pair of split gates to form an electrostatically-defined quantum point contact (QPC). In the low magnetic field regime, the resistance exhibited Fabry-Pérot (FP) resonances due to np'n(pn'p) cavities formed by the top gate. In the quantum Hall (QH) regime with a high magnetic field, the edge states governed the phenomena, presenting a unique condition where the edge channels of electrons and holes along a p-n junction acted as a solid-state analogue of a monochromatic light beam. We observed a crossover from the FP to QH regimes in ballistic graphene QPC under a magnetic field with varying temperatures. In particular, the collapse of the QH effect was elucidated as the magnetic field was decreased. Our high-mobility graphene device enabled observation of such quantum coherence effects up to several tens of kelvins. The presented device could serve as one of the key elements in future electronic quantum optic devices.
    Matched MeSH terms: Static Electricity
  9. Lum CY, Lim KG, Chew KH
    J Phys Condens Matter, 2020 Jun 16;32(42):425401.
    PMID: 32544898 DOI: 10.1088/1361-648X/ab9d4a
    We propose a thermodynamic model to the study the antiferroelectric (AFE) phase transitions in antiferroelectric-ferroelectric (AFE-FE) superlattices in which the coupling at the interface between two layers is mediated by local polarizations. Phase diagram of the AFE layer in term of the degree of interfacial effect λ and temperature T involving ferrielectric (FI) and ferroelectric (FE) phases is investigated. These two phases are stabilized by the interfacial effect and internal electric field. AFE thickness L AFE versus T phase diagram is also constructed. Intermediate regions of two-phase coexistence (IM) emerge in the λ-T and L AFE-T phase diagrams, if certain interface properties λ and layer thickness L AFE criteria are met. These IM regions are metastable states, which exist as a transition state between two phases. A tricritical point locates at the boundaries across the FI, IM and FE phases is found in the L AFE-T phase diagram. Competition among the internal electric field due to the electrostatic coupling, the FE ordering arises from the interfacial effect and the antiferroelectric ordering within the AFE layer giving rises to the rich AFE phase diagram.
    Matched MeSH terms: Static Electricity
  10. Lee CH, Khalina A, Lee SH
    Polymers (Basel), 2021 Jan 29;13(3).
    PMID: 33573036 DOI: 10.3390/polym13030438
    Plant fibers have become a highly sought-after material in the recent days as a result of raising environmental awareness and the realization of harmful effects imposed by synthetic fibers. Natural plant fibers have been widely used as fillers in fabricating plant-fibers-reinforced polymer composites. However, owing to the completely opposite nature of the plant fibers and polymer matrix, treatment is often required to enhance the compatibility between these two materials. Interfacial adhesion mechanisms are among the most influential yet seldom discussed factors that affect the physical, mechanical, and thermal properties of the plant-fibers-reinforced polymer composites. Therefore, this review paper expounds the importance of interfacial adhesion condition on the properties of plant-fiber-reinforced polymer composites. The advantages and disadvantages of natural plant fibers are discussed. Four important interface mechanism, namely interdiffusion, electrostatic adhesion, chemical adhesion, and mechanical interlocking are highlighted. In addition, quantifying and analysis techniques of interfacial adhesion condition is demonstrated. Lastly, the importance of interfacial adhesion condition on the performances of the plant fiber polymer composites performances is discussed. It can be seen that the physical and thermal properties as well as flexural strength of the composites are highly dependent on the interfacial adhesion condition.
    Matched MeSH terms: Static Electricity
  11. Megat Hasnan MM, Mohd Sabri MF, Mohd Said S, Nik Ghazali NN
    ScientificWorldJournal, 2014;2014:912683.
    PMID: 25165751 DOI: 10.1155/2014/912683
    This paper presents the design and evaluation of a high force density fishbone shaped electrostatic comb drive actuator. This comb drive actuator has a branched structure similar to a fishbone, which is intended to increase the capacitance of the electrodes and hence increase the electrostatic actuation force. Two-dimensional finite element analysis was used to simulate the motion of the fishbone shaped electrostatic comb drive actuator and compared against the performance of a straight sided electrostatic comb drive actuator. Performances of both designs are evaluated by comparison of displacement and electrostatic force. For both cases, the active area and the minimum gap distance between the two electrodes were constant. An active area of 800 × 300 μm, which contained 16 fingers of fishbone shaped actuators and 40 fingers of straight sided actuators, respectively, was used. Through simulation, improvement of drive force of the fishbone shaped electrostatic comb driver is approximately 485% higher than conventional electrostatic comb driver. These results indicate that the fishbone actuator design provides good potential for applications as high force density electrostatic microactuator in MEMS systems.
    Matched MeSH terms: Static Electricity*
  12. Webb JF
    Sci Prog, 2003;86(Pt 3):203-34.
    PMID: 15079997
    The main physical properties of ferroelectric crystals are described, and the macroscopic and microscopic viewpoints are discussed along with some applications, such as in capacitors and nonlinear optics. The emphasis is on physical understanding, while the mathematical level is kept to a minimum or supplemented by graphical representations to make the article more accessible.
    Matched MeSH terms: Static Electricity*
  13. Rahmani M, Ahmadi MT, Abadi HK, Saeidmanesh M, Akbari E, Ismail R
    Nanoscale Res Lett, 2013;8(1):55.
    PMID: 23363692 DOI: 10.1186/1556-276X-8-55
    Recent development of trilayer graphene nanoribbon Schottky-barrier field-effect transistors (FETs) will be governed by transistor electrostatics and quantum effects that impose scaling limits like those of Si metal-oxide-semiconductor field-effect transistors. The current-voltage characteristic of a Schottky-barrier FET has been studied as a function of physical parameters such as effective mass, graphene nanoribbon length, gate insulator thickness, and electrical parameters such as Schottky barrier height and applied bias voltage. In this paper, the scaling behaviors of a Schottky-barrier FET using trilayer graphene nanoribbon are studied and analytically modeled. A novel analytical method is also presented for describing a switch in a Schottky-contact double-gate trilayer graphene nanoribbon FET. In the proposed model, different stacking arrangements of trilayer graphene nanoribbon are assumed as metal and semiconductor contacts to form a Schottky transistor. Based on this assumption, an analytical model and numerical solution of the junction current-voltage are presented in which the applied bias voltage and channel length dependence characteristics are highlighted. The model is then compared with other types of transistors. The developed model can assist in comprehending experiments involving graphene nanoribbon Schottky-barrier FETs. It is demonstrated that the proposed structure exhibits negligible short-channel effects, an improved on-current, realistic threshold voltage, and opposite subthreshold slope and meets the International Technology Roadmap for Semiconductors near-term guidelines. Finally, the results showed that there is a fast transient between on-off states. In other words, the suggested model can be used as a high-speed switch where the value of subthreshold slope is small and thus leads to less power consumption.
    Matched MeSH terms: Static Electricity
  14. Tan SL, Halcovitch NR, Tiekink ERT
    Acta Crystallogr E Crystallogr Commun, 2019 Aug 01;75(Pt 8):1133-1139.
    PMID: 31417779 DOI: 10.1107/S2056989019009551
    The asymmetric unit of the title 1:1 solvate, C14H14N4O2·C6H6 [systematic name of the oxalamide mol-ecule: N,N'-bis-(pyridin-4-ylmeth-yl)ethanedi-amide], comprises a half mol-ecule of each constituent as each is disposed about a centre of inversion. In the oxalamide mol-ecule, the central C2N2O2 atoms are planar (r.m.s. deviation = 0.0006 Å). An intra-molecular amide-N-H⋯O(amide) hydrogen bond is evident, which gives rise to an S(5) loop. Overall, the mol-ecule adopts an anti-periplanar disposition of the pyridyl rings, and an orthogonal relationship is evident between the central plane and each terminal pyridyl ring [dihedral angle = 86.89 (3)°]. In the crystal, supra-molecular layers parallel to (10) are generated owing the formation of amide-N-H⋯N(pyrid-yl) hydrogen bonds. The layers stack encompassing benzene mol-ecules which provide the links between layers via methyl-ene-C-H⋯π(benzene) and benzene-C-H⋯π(pyrid-yl) inter-actions. The specified contacts are indicated in an analysis of the calculated Hirshfeld surfaces. The energy of stabilization provided by the conventional hydrogen bonding (approximately 40 kJ mol-1; electrostatic forces) is just over double that by the C-H⋯π contacts (dispersion forces).
    Matched MeSH terms: Static Electricity
  15. Zaini MF, Razak IA, Anis MZ, Arshad S
    Acta Crystallogr E Crystallogr Commun, 2019 Jan 01;75(Pt 1):58-63.
    PMID: 30713734 DOI: 10.1107/S2056989018017371
    The asymmetric unit of the title halogenated chalcone derivative, C15H10BrFO, contains two independent mol-ecules, both adopting an s-cis configuration with respect to the C=O and C=C bonds. In the crystal, centrosymmetrically related mol-ecules are linked into dimers via inter-molecular hydrogen bonds, forming rings with R12(6), R22(10) and R22(14) graph-set motifs. The dimers are further connected by C-H⋯O inter-actions into chains parallel to [001]. A Hirshfeld surface analysis suggests that the most significant contribution to the crystal packing is by H⋯H contacts (26.3%). Calculations performed on the optimized structure obtained using density functional theory (DFT) at B3LYP with the 6-311 G++(d,p) basis set reveal that the HOMO-LUMO energy gap is 4.12 eV, indicating the suitability of this crystal for optoelectronic and biological applications. The nucleophilic and electrophilic binding site regions are elucidated using the mol-ecular electrostatic potential (MEP).
    Matched MeSH terms: Static Electricity
  16. Asiri AM, Alzahrani KAH, Faidallah HM, Alamry KA, Jotani MM, Tiekink ERT
    Acta Crystallogr E Crystallogr Commun, 2019 May 01;75(Pt 5):565-570.
    PMID: 31110787 DOI: 10.1107/S2056989019004389
    The title compound, 2C14H14N4O·H2O, comprises a neutral mol-ecule containing a central pyrazol-3-one ring flanked by an N-bound phenyl group and a C-bound 5-methyl-1H-pyrazol-3-yl group (at positions adjacent to the carbonyl substituent), its zwitterionic tautomer, whereby the N-bound proton of the central ring is now resident on the pendant ring, and a water mol-ecule of crystallization. Besides systematic variations in geometric parameters, the two independent organic mol-ecules have broadly similar conformations, as seen in the dihedral angle between the five-membered rings [9.72 (9)° for the neutral mol-ecule and 3.32 (9)° for the zwitterionic tautomer] and in the dihedral angles between the central and pendant five-membered rings [28.19 (8) and 20.96 (8)° (neutral mol-ecule); 11.33 (9) and 11.81 (9)°]. In the crystal, pyrazolyl-N-H⋯O(carbon-yl) and pyrazolium-N-H⋯N(pyrazol-yl) hydrogen bonds between the independent organic mol-ecules give rise to non-symmetric nine-membered {⋯HNNH⋯NC3O} and {⋯HNN⋯HNC3O} synthons, which differ in the positions of the N-bound H atoms. These aggregates are connected into a supra-molecular layer in the bc plane by water-O-H⋯N(pyrazolide), water-O-H⋯O(carbon-yl) and pyrazolyl-N-H⋯O(water) hydrogen bonding. The layers are linked into a three-dimensional architecture by methyl-C-H⋯π(phen-yl) inter-actions. The different inter-actions, in particular the weaker contacts, formed by the organic mol-ecules are clearly evident in the calculated Hirshfeld surfaces, and the calculated electrostatic potentials differentiate the tautomers.
    Matched MeSH terms: Static Electricity
  17. Lee SL, Tan AL, Young DJ, Jotani MM, Tiekink ER
    Acta Crystallogr E Crystallogr Commun, 2016 Jun 1;72(Pt 6):849-53.
    PMID: 27308057 DOI: 10.1107/S205698901600832X
    The title compound, C13H10N2O2 [also called 1-(pyridin-2-yl)-3-(pyridin-3-yl)propane-1,3-dione], features an almost planar (r.m.s. deviation = 0.0095 Å) central C3O2 core consolidated by an intra-molecular hy-droxy-O-H⋯O(carbon-yl) hydrogen bond. Twists are evident in the mol-ecule, as seen in the dihedral angles between the central core and the 2- and pyridin-3-yl rings of 8.91 (7) and 15.88 (6)°, respectively. The conformation about the C=C bond [1.3931 (17) Å] is Z, and the N atoms lie to the same side of the mol-ecule. In the mol-ecular packing, supra-molecular chains along the a axis are mediated by π(pyridin-2-yl)-π(pyridin-3-yl) inter-actions [inter-centroid distance = 3.7662 (9) Å]. The observation that chains pack with no directional inter-actions between them is consistent with the calculated electrostatic potential, which indicates that repulsive inter-actions dominate.
    Matched MeSH terms: Static Electricity
  18. Zainuri DA, Razak IA, Arshad S
    Acta Crystallogr E Crystallogr Commun, 2018 Jun 01;74(Pt 6):780-785.
    PMID: 29951229 DOI: 10.1107/S2056989018006527
    The mol-ecular and crystal structure of two new chalcone derivatives, (E)-1-(anthracen-9-yl)-3-[4-(piperidin-1-yl)phen-yl]prop-2-en-1-one, C28H25NO, (I), and (E)-1-(anthracen-9-yl)-3-[4-(di-phenyl-amino)-phen-yl]prop-2-en-1-one, C35H25NO, (II), with the fused-ring system at the same position are described. In the crystals of (I) and (II), the mol-ecules are linked via C-H⋯O hydrogen bonds into inversion dimers, forming R22(22) and R22(14) ring motifs, respectively. Weak inter-molecular C-H⋯π inter-actions further help to stabilize the crystal structure, forming a two-dimensional architecture. The mol-ecular structures are optimized using density functional theory (DFT) at B3LYP/6-311 G++(d,p) level and compared with the experimental results. The smallest HOMO-LUMO energy gaps of (I) (exp . 2.76 eV and DFT 3.40 eV) and (II) (exp . 2.70 eV and DFT 3.28 eV) indicates the suitability of these crystals in optoelectronic applications. All inter-molecular contacts and weaker contributions involved in the supra-molecular stabilization are investigated using Hirshfeld surface analysis. The mol-ecular electrostatic potential (MEP) further identifies the positive, negative and neutral electrostatic potential regions of the mol-ecules.
    Matched MeSH terms: Static Electricity
  19. Kwong HC, Mahmud Pathi I, Chidan Kumar CS, Quah CK, Arafath MA
    Acta Crystallogr E Crystallogr Commun, 2018 Jul 01;74(Pt 7):1030-1034.
    PMID: 30002910 DOI: 10.1107/S2056989018009131
    In the cation of the title salt, C17H23N2O+·Br-, the adamantyl moiety and the pyridiniminium ring are inclined to the ketone bridge by torsion angles of -78.1 (2) (C-C-C=O) and 58.3 (2)° (C-C-N-C), respectively, and the ketone bridge has a C-C-C-N torsion angle of 174.80 (15)°. In the crystal, the cations are connected into chains parallel to the c axis by C-H⋯O hydrogen bonds. The chains are further linked into layers parallel to the bc plane by N-H⋯Br and C-H⋯Br hydrogen bonds, C-H⋯π inter-actions and π-π stacking inter-actions [centroid-to-centroid distance = 3.5657 (11) Å]. A Hirshfeld surface analysis, which comprises the dnorm surface, electrostatic potential map and two-dimensional fingerprint plots, was carried out to verify the contribution of the various inter-molecular inter-actions.
    Matched MeSH terms: Static Electricity
  20. Chun YT, Kok SK, Shahidan Radiman, Irman Abdul Rahman, Nur Farhana Amari
    Sains Malaysiana, 2014;43:623-628.
    Catanionic system using anionic sodium bis-(2ethylhexyl)sulfosuccinate (Am) and cationic cetyltrimethylammonium bromide (cTAB) is studied. The system is prepared by addition of CTAB solution to a prepared AOT solution until slight anionic-rich catanionic phase is produced. Catanionic system consists of the mixture of different types of surfactants and counterion due to electrostatic interaction between the oppositely charged surfactant. Both of these products affect the in surface activity of the surfactant. Hydrodynamic diameters decrease and clearer solution were seen with the increase of CTAB concentration in solution mixture. As a result, mixed surfactant with larger hydrophobic region and the presence of counterion will induce smaller vesicle to form in catanionic system.
    Matched MeSH terms: Static Electricity
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