Displaying publications 121 - 140 of 318 in total

Abstract:
Sort:
  1. 3-Iodobenzaldehyde: XRD, FT-IR, Raman and DFT studies
    Kumar CS, Parlak C, Tursun M, Fun HK, Rhyman L, Ramasami P, et al.
    Spectrochim Acta A Mol Biomol Spectrosc, 2015 Jun 15;145:90-7.
    PMID: 25767992 DOI: 10.1016/j.saa.2015.02.079
    The structure of 3-iodobenzaldehyde (3IB) was characterized by FT-IR, Raman and single-crystal X-ray diffraction techniques. The conformational isomers, optimized geometric parameters, normal mode frequencies and corresponding vibrational assignments of 3IB were examined using density functional theory (DFT) method, with the Becke-3-Lee-Yang-Parr (B3LYP) functional and the 6-311+G(3df,p) basis set for all atoms except for iodine. The LANL2DZ effective core basis set was used for iodine. Potential energy distribution (PED) analysis of normal modes was performed to identify characteristic frequencies. 3IB crystallizes in monoclinic space group P21/c with the O-trans form. There is a good agreement between the theoretically predicted structural parameters, and vibrational frequencies and those obtained experimentally. In order to understand halogen effect, 3-halogenobenzaldehyde [XC6H4CHO; X=F, Cl and Br] was also studied theoretically. The free energy difference between the isomers is small but the rotational barrier is about 8kcal/mol. An atypical behavior of fluorine affecting conformational preference is observed.
    Matched MeSH terms: Spectrum Analysis, Raman*
  2. Constituents of the Edible Leaves of Melicope pteleifolia with Potential Analgesic Activity
    Lee BW, Park JG, Ha TKQ, Pham HTT, An JP, Noh JR, et al.
    J Nat Prod, 2019 08 23;82(8):2201-2210.
    PMID: 31393125 DOI: 10.1021/acs.jnatprod.9b00224
    Melicope pteleifolia has long been consumed as a popular vegetable and tea in Southeast Asian countries, including Malaysia and southern mainland China, and is effective in the treatment of colds and inflammation. In the search for active metabolites that can explain its traditional use as an antipyretic, six new phloroacetophenone derivatives (3-8) along with seven known compounds (1, 2, and 9-13) were isolated from the leaves of M. pteleifolia. Their chemical structures were confirmed by extensive spectroscopic analysis including NMR, IR, ECD, and HRMS. All compounds isolated from the leaves of M. pteleifolia (1-13) have a phloroacetophenone skeleton. Notably, the new compound 8 contains an additional cyclobutane moiety in its structure. The bioactivities of the isolated compounds were evaluated, and compounds 1, 6, and 7 inhibited tumor necrosis factor-α-induced prostaglandin E2. Moreover, the major constituent, 3,5-di-C-β-d-glucopyranosyl phloroacetophenone (1), was found to be responsible for the antipyretic activity of M. pteleifolia based on in vivo experiments.
    Matched MeSH terms: Spectrum Analysis/methods
  3. Conolodinines A-D, Aspidosperma- Aspidosperma Bisindole Alkaloids with Antiproliferative Activity from Tabernaemontana corymbosa
    Sim DS, Navanesan S, Sim KS, Gurusamy S, Lim SH, Low YY, et al.
    J Nat Prod, 2019 04 26;82(4):850-858.
    PMID: 30869890 DOI: 10.1021/acs.jnatprod.8b00919
    Examination of the EtOH extract of the leaves of the Malayan Tabernaemontana corymbosa resulted in the isolation of four new (1-4) and two known bisindole alkaloids (5, 6) of the Aspidosperma- Aspidosperma type. The structures of these alkaloids were determined based on analysis of the spectroscopic data (NMR and HRESIMS). X-ray diffraction analyses of the related bisindole alkaloids conophylline (5) and conophyllinine (6) established the absolute configurations. Treatment of the bisindole alkaloid conophylline (5) with benzeneselenic anhydride gave, in addition to the known bisindole polyervinine (7) previously isolated from another Malayan Tabernaemontana, another bisindole product, 8, an isolable tautomer of 7. X-ray diffraction analyses yielded the absolute configurations of both bisindoles and in addition showed that polyervinine (7) exists primarily as the neutral dione structure. The bisindoles (1-8) and the related conophylline-type bisindoles (9-13) showed pronounced in vitro growth inhibitory activity against an array of human cancer cell lines, including KB, vincristine-resistant KB, PC-3, LNCaP, MCF7, MDA-MB-231, A549, HT-29, and HCT 116 cells, with IC50 values for the active compounds in the 0.01-5 μM range.
    Matched MeSH terms: Spectrum Analysis/methods
  4. Profiling of drug crystallization in the skin
    Goh CF, Boyd BJ, Craig DQM, Lane ME
    Expert Opin Drug Deliv, 2020 09;17(9):1321-1334.
    PMID: 32634033 DOI: 10.1080/17425247.2020.1792440
    BACKGROUND: Drug crystallization following application of transdermal and topical formulations may potentially compromise the delivery of drugs to the skin. This phenomenon was found to be limited to the superficial layers of the stratum corneum (~7 µm) in our recent reports and tape stripping of the skin samples was necessary. It remains a significant challenge to profile drug crystallization in situ without damaging the skin samples.

    METHODS: This work reports the application of an X-ray microbeam via synchrotron SAXS/WAXS analysis to monitor drug crystallization in the skin, especially in the deeper skin layers. Confocal Raman spectroscopy (CRS) was employed to examine drug distribution in the skin to complement the detection of drug crystallization using SAXS/WAXS analysis.

    RESULTS: Following application of saturated drug solutions (ibuprofen, diclofenac acid, and salts), CRS depth profiles confirmed that the drugs generally were delivered to a depth of ~15 - 20 µm in the skin. This was compared with the WAXS profiles that measured drug crystal diffraction at a depth of up to ~25 µm of the skin.

    CONCLUSION: This study demonstrates the potential of synchrotron SAXS/WAXS analysis for profiling of drug crystallization in situ in the deeper skin layers without pre-treatment for the skin samples. [Figure: see text].

    Matched MeSH terms: Spectrum Analysis, Raman/methods
  5. Signal Enhancement Evaluation of Laser-Induced Breakdown Spectroscopy of Extracted Animal Fats Using Principal Component Analysis Approach
    Hanasil NS, Raja Ibrahim RK, Duralim M, Sapingi HHJ, Mahdi MA
    Appl Spectrosc, 2020 Dec;74(12):1452-1462.
    PMID: 32166979 DOI: 10.1177/0003702820915532
    In this work, principal component analysis (PCA) was utilized to analyze laser-induced breakdown spectroscopy (LIBS) signals of the extracted chicken fat, lamb fat, beef fat, and lard froze using two different freezing methods. The frozen samples were ablated using a neodymium-doped yttrium aluminum garnet (Nd:YAG) laser with a wavelength of 1064 nm, 170 mJ pulse energy, and 6 ns pulse duration to produce plasma on target surfaces. The samples were ablated using 30-60 shots of the laser beam at different spots. Stronger LIBS signals from the extracted chicken fat and lamb fat were obtained with liquid nitrogen (LN2) method. However, LIBS signals obtained from the freezer freezing method were found to be stronger for extracted beef fat and lard. The PCA was then used to visualize the LIBS spectra of extracted animal fats into a score plot. Data points of each extracted animal fat were divided into three groups representing LIBS spectra collected at the early, middle, and end part of the ablation process. The score plot revealed that the data points of the three groups of frozen extracted animal fats using the LN2 method were more closely clustered than those frozen in the freezer. Good discrimination with 97% of the variance was achieved between the extracted chicken fat, lamb fat, beef fat, and lard using the LN2 method in the three-dimensional score plot. LIBS signals of the extracted animal fats produced from the LN2 method were found to be more stable than those from the freezer method.
    Matched MeSH terms: Spectrum Analysis/methods*
  6. Biophysical characterization of a recombinant lipase KV1 from Acinetobacter haemolyticus in relation to pH and temperature
    Batumalaie K, Khalili E, Mahat NA, Huyop F, Wahab RA
    Biochimie, 2018 Sep;152:198-210.
    PMID: 30036604 DOI: 10.1016/j.biochi.2018.07.011
    Spectroscopic and calorimetric methods were employed to assess the stability and the folding aspect of a novel recombinant alkaline-stable lipase KV1 from Acinetobacter haemolyticus under varying pH and temperature. Data on far ultraviolet-circular dichroism of recombinant lipase KV1 under two alkaline conditions (pH 8.0 and 12.0) at 40 °C reveal strong negative ellipticities at 208, 217, 222 nm, implying its secondary structure belonging to a α + β class with 47.3 and 39.0% ellipticity, respectively. Results demonstrate that lipase KV1 adopts its most stable conformation at pH 8.0 and 40 °C. Conversely, the protein assumes a random coil structure at pH 4.0 and 80 °C, evident from a strong negative peak at ∼ 200 nm. This blue shift suggests a general decline in enzyme activity in conjunction with the partially or fully unfolded state that invariably exposed more hydrophobic surfaces of the lipase protein. The maximum emission at ∼335 nm for pH 8.0 and 40 °C indicates the adoption of a favorable protein conformation with a high number of buried tryptophan residues, reducing solvent exposure. Appearance of an intense Amide I absorption band at pH 8.0 corroborates an intact secondary structure. A lower enthalpy value for pH 4.0 over pH 8.0 and 12.0 in the differential scanning calorimetric data corroborates the stability of the lipase at alkaline conditions, while a low Km (0.68 ± 0.03 mM) for tributyrin verifies the high affinity of lipase KV1 for the substrate. The data, herein offer useful insights into future structure-based tunable catalytic activity of lipase KV1.
    Matched MeSH terms: Spectrum Analysis/methods
  7. Dual platform based sandwich assay surface-enhanced Raman scattering DNA biosensor for the sensitive detection of food adulteration
    Khalil I, Yehye WA, Muhd Julkapli N, Sina AA, Rahmati S, Basirun WJ, et al.
    Analyst, 2020 Feb 17;145(4):1414-1426.
    PMID: 31845928 DOI: 10.1039/c9an02106j
    Surface enhanced Raman scattering (SERS) DNA biosensing is an ultrasensitive, selective, and rapid detection technique with the ability to produce molecule-specific distinct fingerprint spectra. It supersedes the long amplicon based PCR assays, the fluorescence and spectroscopic techniques with their quenching and narrow spectral bandwidth, and the electrochemical detection techniques using multiplexing. However, the performance of the SERS DNA biosensor relies on the DNA probe length, platform composition, both the presence and position of Raman tags and the chosen sensing strategy. In this context, we herein report a SERS biosensor based on dual nanoplatforms with a uniquely designed Raman tag (ATTO Rho6G) intercalated short-length DNA probe for the sensitive detection of the pig species Sus scrofa. In the design of the signal probe (SP), a Raman tag was incorporated adjacent to the spacer arm, followed by a terminal thiol modifier, which consequently had a strong influence on the SERS signal enhancement. The detection strategy involves the probe-target DNA hybridization mediated coupling of the two platforms, i.e., the graphene oxide-gold nanorod (GO-AuNR) functionalized capture probe (CP) and SP-conjugated gold nanoparticles (AuNPs), consequently enhancing the SERS intensity by both the electromagnetic hot spots generated at the junctions or interstices of the two platforms and the chemical enhancement between the AuNPs and the adsorbed intercalated Raman tag. This dual platform based SERS DNA biosensor exhibited outstanding sensitivity in detecting pork DNA with a limit of detection (LOD) of 100 aM validated with DNA extracted from a pork sample (LOD 1 fM). Moreover, the fabricated SERS biosensor showed outstanding selectivity and specificity for differentiating the DNA sequences of six closely related non-target species from the target DNA sequences with single and three nucleotide base-mismatches. Therefore, the developed short-length DNA linked dual platform based SERS biosensor could replace the less sensitive traditional methods of pork DNA detection and be adopted as a universal detection approach for the qualitative and quantitative detection of DNA from any source.
    Matched MeSH terms: Spectrum Analysis, Raman*
  8. Fulltext Precursors to non-invasive clinical dengue screening: Multivariate signature analysis of in-vivo diffuse skin reflectance spectroscopy on febrile patients in Malaysia
    Poh AH, Mahamd Adikan FR, Moghavvemi M, Syed Omar SF, Poh K, Mahyuddin MBH, et al.
    PLoS One, 2020;15(4):e0228923.
    PMID: 32236132 DOI: 10.1371/journal.pone.0228923
    Dengue diagnostics have come a long way. Attempts at breaking away from lab-oriented dengue detection, such as NS1 antigen, IgM or IgG antibodies detection have extensively received numerous coverage. As a result, rapid detection tests (RDTs) have started to gain inroads in medical practice. Rapid detection tests notwithstanding, analysis of blood serum is still a relatively complicated task. This includes the necessity of phlebotomy, centrifugation for blood serum, and other reagent-based tests. Therefore, a non-invasive method of dengue detection was considered. In this study, we present the utility of diffuse reflectance skin spectroscopy (bandwidth of 200-2500nm) on the forearm during the triaging period for dengue screening potential. This is performed with multivariate analysis of 240 triaged febrile/suspected dengue patients. The data is then scrutinized for its clinical validity to be included as either confirmed or probable dengue, or a control group. Based on discriminant analysis of several data normalization models, we can predict the patients' clinical dengue-positivity at ranges of accuracy between ~93-98% depending on mode of the data, with a probably optimal sensitivity and specificity to the clinical diagnosis of ~89% and ~100% respectively. From the outcomes of this study, we recommend further trials with cautious optimism. With these findings, it is hoped that the elusive non-invasive detection of tropical diseases may gain platform in the near future.
    Matched MeSH terms: Spectrum Analysis/methods*
  9. A Cytotoxic Indole Characterized by Incorporation of a Unique Carbon-Nitrogen Skeleton and Two Pentacyclic Corynanthean Alkaloids Incorporating a Substituted Tetrahydrofuranone Ring from Kopsia arborea
    Wong SK, Wong SP, Sim KS, Lim SH, Low YY, Kam TS
    J Nat Prod, 2019 07 26;82(7):1902-1907.
    PMID: 31241923 DOI: 10.1021/acs.jnatprod.9b00255
    Three new alkaloids were isolated from the bark extract of the Malayan Kopsia arborea, viz., arbophyllidine (1), an unusual pentacyclic, monoterpenoid indole characterized by an absence of oxygen atoms and incorporating a new carbon-nitrogen skeleton, and arbophyllinines A (2) and B (3), two pentacyclic corynanthean alkaloids incorporating a hydroxyethyl-substituted tetrahydrofuranone ring. The structures of the alkaloids were deduced based on analysis of the MS and NMR data and confirmed by X-ray diffraction analyses. The absolute configuration of arbophyllidine (1) was established based on experimental and calculated ECD data, while that of arbophyllinine A was based on X-ray diffraction analysis (Cu Kα). A reasonable biosynthetic route to arbophyllidine (1) from a pericine precursor is presented. Arbophyllidine (1) showed pronounced in vitro growth inhibitory activity against the HT-29 human cancer cell line with IC50 6.2 μM.
    Matched MeSH terms: Spectrum Analysis/methods
  10. Current analytical methods for porcine identification in meat and meat products
    Zia Q, Alawami M, Mokhtar NFK, Nhari RMHR, Hanish I
    Food Chem, 2020 Sep 15;324:126664.
    PMID: 32380410 DOI: 10.1016/j.foodchem.2020.126664
    Authentication of meat products is critical in the food industry. Meat adulteration may lead to religious apprehensions, financial gain and food-toxicities such as meat allergies. Thus, empirical validation of the quality and constituents of meat is paramount. Various analytical methods often based on protein or DNA measurements are utilized to identify meat species. Protein-based methods, including electrophoretic and immunological techniques, are at times unsuitable for discriminating closely related species. Most of these methods have been replaced by more accurate and sensitive detection methods, such as DNA-based techniques. Emerging technologies like DNA barcoding and mass spectrometry are still in their infancy when it comes to their utilization in meat detection. Gold nanobiosensors have shown some promise in this regard. However, its applicability in small scale industries is distant. This article comprehensively reviews the recent developments in the field of analytical methods used for porcine identification.
    Matched MeSH terms: Spectrum Analysis/methods
  11. Fulltext Indication of high lipid content in epithelial-mesenchymal transitions of breast tissues
    Sabtu SN, Sani SFA, Looi LM, Chiew SF, Pathmanathan D, Bradley DA, et al.
    Sci Rep, 2021 Feb 05;11(1):3250.
    PMID: 33547362 DOI: 10.1038/s41598-021-81426-x
    The epithelial-mesenchymal transition (EMT) is a crucial process in cancer progression and metastasis. Study of metabolic changes during the EMT process is important in seeking to understand the biochemical changes associated with cancer progression, not least in scoping for therapeutic strategies aimed at targeting EMT. Due to the potential for high sensitivity and specificity, Raman spectroscopy was used here to study the metabolic changes associated with EMT in human breast cancer tissue. For Raman spectroscopy measurements, tissue from 23 patients were collected, comprising non-lesional, EMT and non-EMT formalin-fixed and paraffin embedded breast cancer samples. Analysis was made in the fingerprint Raman spectra region (600-1800 cm-1) best associated with cancer progression biochemical changes in lipid, protein and nucleic acids. The ANOVA test followed by the Tukey's multiple comparisons test were conducted to see if there existed differences between non-lesional, EMT and non-EMT breast tissue for Raman spectroscopy measurements. Results revealed that significant differences were evident in terms of intensity between the non-lesional and EMT samples, as well as the EMT and non-EMT samples. Multivariate analysis involving independent component analysis, Principal component analysis and non-negative least square were used to analyse the Raman spectra data. The results show significant differences between EMT and non-EMT cancers in lipid, protein, and nucleic acids. This study demonstrated the capability of Raman spectroscopy supported by multivariate analysis in analysing metabolic changes in EMT breast cancer tissue.
    Matched MeSH terms: Spectrum Analysis, Raman/methods
  12. Fulltext Optical properties of ZnO/BaCO3 nanocomposites in UV and visible regions
    Zak AK, Hashim AM, Darroudi M
    Nanoscale Res Lett, 2014;9(1):399.
    PMID: 25177218 DOI: 10.1186/1556-276X-9-399
    Pure zinc oxide and zinc oxide/barium carbonate nanoparticles (ZnO-NPs and ZB-NPs) were synthesized by the sol-gel method. The prepared powders were characterized by X-ray diffraction (XRD), ultraviolet-visible (UV-Vis), Auger spectroscopy, and transmission electron microscopy (TEM). The XRD result showed that the ZnO and BaCO3 nanocrystals grow independently. The Auger spectroscopy proved the existence of carbon in the composites besides the Zn, Ba, and O elements. The UV-Vis spectroscopy results showed that the absorption edge of ZnO nanoparticles is redshifted by adding barium carbonate. In addition, the optical parameters including the refractive index and permittivity of the prepared samples were calculated using the UV-Vis spectra.
    Matched MeSH terms: Spectrum Analysis
  13. Fulltext Structural and optical properties of ITO/TiO2 anti-reflective films for solar cell applications
    Ali K, Khan SA, Jafri MZ
    Nanoscale Res Lett, 2014;9(1):175.
    PMID: 24721986 DOI: 10.1186/1556-276X-9-175
    Indium tin oxide (ITO) and titanium dioxide (TiO2) anti-reflective coatings (ARCs) were deposited on a (100) P-type monocrystalline Si substrate by a radio-frequency (RF) magnetron sputtering. Polycrystalline ITO and anatase TiO2 films were obtained at room temperature (RT). The thickness of ITO (60 to 64 nm) and TiO2 (55 to 60 nm) films was optimized, considering the optical response in the 400- to 1,000-nm wavelength range. The deposited films were characterized by X-ray diffraction (XRD), Raman spectroscopy, field emission scanning electron microscopy (FESEM), energy dispersive spectroscopy (EDS), and atomic force microscopy (AFM). The XRD analysis showed preferential orientation along (211) and (222) for ITO and (200) and (211) for TiO2 films. The XRD analysis showed that crystalline ITO/TiO2 films could be formed at RT. The crystallite strain measurements showed compressive strain for ITO and TiO2 films. The measured average optical reflectance was about 12% and 10% for the ITO and TiO2 ARCs, respectively.
    Matched MeSH terms: Spectrum Analysis, Raman
  14. Fulltext Temperature-dependent properties of silver-poly(methylmethacrylate) nanocomposites synthesized by in-situ technique
    Singho ND, Johan MR, Lah NA
    Nanoscale Res Lett, 2014;9(1):42.
    PMID: 24450850 DOI: 10.1186/1556-276X-9-42
    Ag/PMMA nanocomposites were successfully synthesized by in-situ technique. Transmission electron microscopy (TEM) images show that the particles are spherical in shape and their sizes are dependent on temperature. The smallest particle achieved high stability as indicated from Zeta sizer analysis. The red shift of surface plasmon resonance (SPR) indicated the increases of particle sizes. X-ray diffraction (XRD) patterns exhibit a two-phase (crystalline and amorphous) structure of Ag/PMMA nanocomposites. The complexation of Ag/PMMA nanocomposites was confirmed using Raman spectroscopy. Fourier transform infrared spectroscopy spectra confirmed that the bonding was dominantly influenced by the PMMA and DMF solution. Finally, thermogravimetric analysis (TGA) results indicate that the total weight loss increases as the temperature increases.
    Matched MeSH terms: Spectrum Analysis, Raman
  15. Label-free methods of reporting biomolecular interactions by optical biosensors
    Citartan M, Gopinath SC, Tominaga J, Tang TH
    Analyst, 2013 Jul 7;138(13):3576-92.
    PMID: 23646346 DOI: 10.1039/c3an36828a
    Reporting biomolecular interactions has become part and parcel of many applications of science towards an in-depth understanding of disease and gene regulation. Apart from that, in diagnostic applications where biomolecules (antibodies and aptamers) are vastly applied, meticulous monitoring of biomolecular interaction is vital for clear-cut diagnosis. Several currently available methods of analyzing the interaction of the ligands with the appropriate analytes are aided by labeling using fluorescence or luminescence techniques. However, labeling is cumbersome and can occupy important binding sites of interactive molecules to be labeled, which may interfere with the conformational changes of the molecules and increase non-specificity. Optical-based sensing can provide an alternative way as a label-free procedure for monitoring biomolecular interactions. Optical sensors affiliated with different operating principles, including surface plasmon changes, scattering and interferometry, can impart a huge impact for in-house and point-of-care applications. This optical-based biosensing permits real-time monitoring, obviating the use of hazardous labeling molecules such as radioactive tags. Herein, label-free ways of reporting biomolecular interactions by various optical biosensors were gleaned.
    Matched MeSH terms: Spectrum Analysis
  16. Fulltext A simple route to vertical array of quasi-1D ZnO nanofilms on FTO surfaces: 1D-crystal growth of nanoseeds under ammonia-assisted hydrolysis process
    Ali Umar A, Abd Rahman MY, Taslim R, Mat Salleh M, Oyama M
    Nanoscale Res Lett, 2011 Oct 25;6:564.
    PMID: 22027275 DOI: 10.1186/1556-276X-6-564
    A simple method for the synthesis of ZnO nanofilms composed of vertical array of quasi-1D ZnO nanostructures (quasi-NRs) on the surface was demonstrated via a 1D crystal growth of the attached nanoseeds under a rapid hydrolysis process of zinc salts in the presence of ammonia at room temperature. In a typical procedure, by simply controlling the concentration of zinc acetate and ammonia in the reaction, a high density of vertically oriented nanorod-like morphology could be successfully obtained in a relatively short growth period (approximately 4 to 5 min) and at a room-temperature process. The average diameter and the length of the nanostructures are approximately 30 and 110 nm, respectively. The as-prepared quasi-NRs products were pure ZnO phase in nature without the presence of any zinc complexes as confirmed by the XRD characterisation. Room-temperature optical absorption spectroscopy exhibits the presence of two separate excitonic characters inferring that the as-prepared ZnO quasi-NRs are high-crystallinity properties in nature. The mechanism of growth for the ZnO quasi-NRs will be proposed. Due to their simplicity, the method should become a potential alternative for a rapid and cost-effective preparation of high-quality ZnO quasi-NRs nanofilms for use in photovoltaic or photocatalytics applications.PACS: 81.07.Bc; 81.16.-c; 81.07.Gf.
    Matched MeSH terms: Spectrum Analysis
  17. Fulltext Alkaloids from Fissistigma latifolium (Dunal) Merr
    Alias A, Hazni H, Jaafar FM, Awang K, Ismail NH
    Molecules, 2010 Jul;15(7):4583-8.
    PMID: 20657378 DOI: 10.3390/molecules15074583
    A phytochemical study of the bark of Fissistigma latifolium (Annonaceae) yielded a new aporphine alkaloid, (-)-N-methylguattescidine (1), and eight known alkaloids: liriodenine (2), oxoxylopine (3), (-)-asimilobine (4), dimethyltryptamine (5), (-)-remerine (6), (-)-anonaine (7), columbamine (8) and lysicamine (9). The compounds were isolated using various chromatographic methods and structural elucidation was accomplished by means of spectroscopic methods, notably 1D-NMR ((1)H, (13)C, DEPT), 2D-NMR (COSY, HMQC, HMBC), UV, IR and MS.
    Matched MeSH terms: Spectrum Analysis
  18. Electrophoretic methods for separation of nanoparticles
    Surugau N, Urban PL
    J Sep Sci, 2009 Jun;32(11):1889-906.
    PMID: 19479769 DOI: 10.1002/jssc.200900071
    This article reviews progress in the application of electrophoretic techniques for the separation of nanoparticles. Numerous types of nanoparticles have recently been synthesised and integrated into different products and procedures. Consequently, analytical methods for the efficient characterisation of nanoparticles are now required. Several studies have revealed that gel electrophoresis can readily be used for separating nanoparticles according to their size or shape. However, many other studies focused on separation of nanoparticles by CE. In some cases nanoparticles could be separated by CZE, simply using pure buffer as the BGE. In other studies, buffer additives (most often SDS) were used, enabling fast separations of metallic nanoparticles by size. Other CE methods also allowed for separation of nanoparticle conjugates with biomolecules. Dielectrophoresis is yet another electrophoretic technique useful in separation and characterisation of nanoparticles; particularly nanotubes. Detection methods often used after electrophoretic separation include UV/Vis absorption and fluorescence spectroscopy. Examples of recent and relevant older reports are presented here. The authors conclude that electrophoretic methods for nanoanalysis can provide inexpensive and efficient tools for quality assurance and safety control; and as a consequence, they can augment transfer of nanotechnologies from research to industry.
    Matched MeSH terms: Spectrum Analysis, Raman
  19. Fulltext Influence of dose on particle size and optical properties of colloidal platinum nanoparticles
    Gharibshahi E, Saion E
    Int J Mol Sci, 2012;13(11):14723-41.
    PMID: 23203091 DOI: 10.3390/ijms131114723
    Attempts to produce colloidal platinum nanoparticles by using steady absorption spectra with various chemical-based reduction methods often resulted in the fast disappearance of the absorption maxima leaving reduced platinum nanoparticles with little information on their optical properties. We synthesized colloidal platinum nanoparticles in an aqueous solution of polyvinyl pyrrolidone by gamma radiolytic reduction method, which produced steady absorption spectra of fully reduced and highly pure platinum nanoparticles free from by-product impurities or reducing agent contamination. The average particle size was found to be in the range of 3.4–5.3 nm and decreased with increasing dose due to the domination of nucleation over ion association in the formation of metal nanoparticles by the gamma radiolytic reduction method. The platinum nanoparticles exhibit optical absorption spectra with two absorption peaks centered at about 216 and 264 nm and the peaks blue shifted to lower wavelengths with decreasing particle size. The absorption spectra of platinum nanoparticles were also calculated using quantum mechanical treatment and coincidently a good agreement was obtained between the calculated and measured absorption peaks at various particle sizes. This indicates that the 216 and 264-nm absorption peaks of platinum nanoparticles conceivably originated from the intra-band transitions of conduction electrons of (n = 5, l = 2) and (n = 6, l = 0) energy states respectively to higher energy states. The absorption energies, i.e., conduction band energies of platinum nanoparticles derived from the absorption peaks increased with increasing dose and decreased with increasing particle size.
    Matched MeSH terms: Spectrum Analysis
  20. Fulltext Synthesis and Characterizations of Novel Ca-Mg-Ti-Fe-Oxides Based Ceramic Nanocrystals and Flexible Film of Polydimethylsiloxane Composite with Improved Mechanical and Dielectric Properties for Sensors
    Tripathy A, Pramanik S, Manna A, Shah NF, Shasmin HN, Radzi Z, et al.
    Sensors (Basel), 2016;16(3):292.
    PMID: 26927116 DOI: 10.3390/s16030292
    Armalcolite, a rare ceramic mineral and normally found in the lunar earth, was synthesized by solid-state step-sintering. The in situ phase-changed novel ceramic nanocrystals of Ca-Mg-Ti-Fe based oxide (CMTFOx), their chemical reactions and bonding with polydimethylsiloxane (PDMS) were determined by X-ray diffraction, infrared spectroscopy, and microscopy. Water absorption of all the CMTFOx was high. The lower dielectric loss tangent value (0.155 at 1 MHz) was obtained for the ceramic sintered at 1050 °C (S1050) and it became lowest for the S1050/PDMS nanocomposite (0.002 at 1 MHz) film, which was made by spin coating at 3000 rpm. The excellent flexibility (static modulus ≈ 0.27 MPa and elongation > 90%), viscoelastic property (tanδ = E″/E': 0.225) and glass transition temperature (Tg: -58.5 °C) were obtained for S1050/PDMS film. Parallel-plate capacitive and flexible resistive humidity sensors have been developed successfully. The best sensing performance of the present S1050 (3000%) and its flexible S1050/PDMS composite film (306%) based humidity sensors was found to be at 100 Hz, better than conventional materials.
    Matched MeSH terms: Spectrum Analysis
Related Terms
Filters
Contact Us

Please provide feedback to Administrator (afdal@afpm.org.my)

External Links