Lipophilicity Assessment of Ruthenium(II)-Arene Complexes by the Means of Reversed-Phase Thin-Layer Chromatography and DFT Calculations

PubMed Central

Shweshein, Khalil Salem A. M.; Andrić, Filip; Radoičić, Aleksandra; Gruden-Pavlović, Maja; Tešić, Živoslav; Milojković-Opsenica, Dušanka

2014-01-01

The lipophilicity of ten ruthenium(II)-arene complexes was assessed by reversed-phase thin-layer chromatography (RP-TLC) on octadecyl silica stationary phase. The binary solvent systems composed of water and acetonitrile were used as mobile phase in order to determine chromatographic descriptors for lipophilicity estimation. Octanol-water partition coefficient, logK OW, of tested complexes was experimentally determined using twenty-eight standard solutes which were analyzed under the same chromatographic conditions as target substances. In addition, ab initio density functional theory (DFT) computational approach was employed to calculate logK OW values from the differences in Gibbs' free solvation energies of the solute transfer from n-octanol to water. A good overall agreement between DFT calculated and experimentally determined logK OW values was established (R 2 = 0.8024–0.9658). PMID:24587761

[A thin-layer chromatography method for determining the styrene metabolites mandelic and phenylglyoxylic acid in urine].

PubMed

Gartzke, J; Burck, D

1989-06-01

A thin-layer chromatographic method is described for the determination of mandelic and phenyglyoxillic acid on silicagel (Silufol UV 254) after extraction from urine of styrene exposed workers. The quantitative determination was performed after eluting the spots. Phenylglyoxilic acid was measured at 255 nm and mandelic acid by derivative spectroscopically estimation of the .CH(OH).COOH -chromophore at 217 nm or by a three-wavelength mode, respectively. The recovery in urine was 80-104% for phenylglyoxilic acid and 99-105% for mandelic acid.

Liquid chromatographic separation of terpenoid pigments in foods and food products.

PubMed

Cserháti, T; Forgács, E

2001-11-30

The newest achievements in the use of various liquid chromatographic techniques such as adsorption and reversed-phase thin-layer chromatography and HPLC employed for the separation and quantitative determination of terpenoid-based color substances in foods and food products are reviewed. The techniques applied for the analysis of individual pigments and pigments classes are surveyed and critically evaluated. Future trends in the separation and identification of pigments in foods and food products are delineated.

Quantitative thin layer chromatographic multi-sulfonamide screening procedure.

PubMed

Thomas, M H; Soroka, K E; Thomas, S H

1983-07-01

In-situ optical scanning of fluorescamine derivatives on thin layer silica gel plates provides a rapid method for the determination of multiple sulfonamides at levels below 0.1 ppm. Sample preparation is minimal. Homogenized liver or muscle is extracted with ethyl acetate and then back-extracted into 0.2M glycine buffer. After pH adjustment, the extract is washed with hexane and extracted with methylene chloride. The organic phase is evaporated to dryness and reconstituted in methanol. Pre-adsorbent layer silica gel plates are used for chromatography. The method has been applied to residues of sulfamethazine, sulfadimethoxine, sulfathiazole, sulfaquinoxaline, and sulfabromomethazine in cattle, swine, turkey, and duck tissues.

Simultaneous quantification of withanolides in Withania somnifera by a validated high-performance thin-layer chromatographic method.

PubMed

Srivastava, Pooja; Tiwari, Neerja; Yadav, Akhilesh K; Kumar, Vijendra; Shanker, Karuna; Verma, Ram K; Gupta, Madan M; Gupta, Anil K; Khanuja, Suman P S

2008-01-01

This paper describes a sensitive, selective, specific, robust, and validated densitometric high-performance thin-layer chromatographic (HPTLC) method for the simultaneous determination of 3 key withanolides, namely, withaferin-A, 12-deoxywithastramonolide, and withanolide-A, in Ashwagandha (Withania somnifera) plant samples. The separation was performed on aluminum-backed silica gel 60F254 HPTLC plates using dichloromethane-methanol-acetone-diethyl ether (15 + 1 + 1 + 1, v/v/v/v) as the mobile phase. The withanolides were quantified by densitometry in the reflection/absorption mode at 230 nm. Precise and accurate quantification could be performed in the linear working concentration range of 66-330 ng/band with good correlation (r2 = 0.997, 0.999, and 0.996, respectively). The method was validated for recovery, precision, accuracy, robustness, limit of detection, limit of quantitation, and specificity according to International Conference on Harmonization guidelines. Specificity of quantification was confirmed using retention factor (Rf) values, UV-Vis spectral correlation, and electrospray ionization mass spectra of marker compounds in sample tracks.

Thin-layer chromatographic technique for rapid detection of bacterial phospholipases.

PubMed

Legakis, N J; Papavassiliou, J

1975-11-01

Silica gel thin-layer chromatography was employed to detect lecithinase activity induced from bacterial resting cell preparations induced from bacterial resting cell preparations incubated at 37 C for 4 h in the presence of purified egg yolk lecithin. Bacillus subtilis, Bacillus cereus, Serratia marcescens, and Pseudomonas aeruginosa hydrolyzed lecithin with the formation of free fatty acids as the sole lipid-soluble product. In none of the Escherichia coli and Citrobacter freundii strains tested could lecithinase activity be detected. Four among eight strains of Enterobacter aerogenes and one among 12 strains of Proteus tested produced negligible amounts of free fatty acid.

Variables affecting resolution of lung phospholipids in one-dimensional thin-layer chromatography.

PubMed

Krahn, J

1987-01-01

Resolution of the confusion in the literature about the separation of lung phospholipids in thin-layer chromatographic systems has awaited a systematic study of the variables that potentially affect this separation. In this study I show that: incorporation of ammonium sulfate into silica gel "GHL" has a dramatic effect on separation of lung phospholipids; this effect is equally dramatic but different in activated and nonactivated gels; when it picks up moisture, ammonium sulfate-activated gel very rapidly loses its ability to resolve lecithin from phosphatidylinositol; in gel containing ammonium sulfate, small amounts of phosphatidylethanolamine are hydrolyzed to lyso-phosphatidylethanolamine.

Isolation and Identification of Echinenone from Micrococcus roseus

PubMed Central

Schwartzel, E. H.; Cooney, J. J.

1970-01-01

An orange carotenoid from Micrococcus roseus was purified by solvent partitioning followed by column and thin-layer chromatography. Absorption spectra, chromatographic mobility, and partition coefficient suggested that the pigment was echinenone (4-keto-β-carotene). Reduction yielded a pigment with the spectral and polar properties of isocryptoxanthin (4-hydroxy-β-carotene), the expected product. The orange pigment and its reduction product co-chromatographed with the respective authentic pigments, confirming the original pigment as echinenone. To our knowledge echinenone has not been identified previously as a bacterial pigment. PMID:5473895

Thin-layer chromatographic separation of conjugates of ursodeoxycholic acid from those of litho-, chenodeoxy-, deoxy-, and cholic acids.

PubMed

Batta, A K; Shefer, S; Salen, G

1981-05-01

Separation of the glycine and taurine conjugates of ursodeoxycholic acid from those of lithocholic acid, chenodeoxycholic acid, deoxycholic acid, and cholic acid by thin-layer chromatography is described. Thus, on running a silica gel G plate first in a solvent system of n-butanol-water 20:3 and then in a second solvent system of chloroform-isopropanol-acetic acid-water 30:20:4:1, all the above-mentioned conjugated bile acids are separated from one another. The application of this method to study the change in the biliary bile acid conjugation pattern in ursodeoxycholic acid-fed gallstone patients is described.

Employment of High-Performance Thin-Layer Chromatography for the Quantification of Oleuropein in Olive Leaves and the Selection of a Suitable Solvent System for Its Isolation with Centrifugal Partition Chromatography.

PubMed

Boka, Vasiliki-Ioanna; Argyropoulou, Aikaterini; Gikas, Evangelos; Angelis, Apostolis; Aligiannis, Nektarios; Skaltsounis, Alexios-Leandros

2015-11-01

A high-performance thin-layer chromatographic methodology was developed and validated for the isolation and quantitative determination of oleuropein in two extracts of Olea europaea leaves. OLE_A was a crude acetone extract, while OLE_AA was its defatted residue. Initially, high-performance thin-layer chromatography was employed for the purification process of oleuropein with fast centrifugal partition chromatography, replacing high-performance liquid-chromatography, in the stage of the determination of the distribution coefficient and the retention volume. A densitometric method was developed for the determination of the distribution coefficients, KC = CS/CM. The total concentrations of the target compound in the stationary phase (CS) and in the mobile phase (CM) were calculated by the area measured in the high-performance thin-layer chromatogram. The estimated Kc was also used for the calculation of the retention volume, VR, with a chromatographic retention equation. The obtained data were successfully applied for the purification of oleuropein and the experimental results confirmed the theoretical predictions, indicating that high-performance thin-layer chromatography could be an important counterpart in the phytochemical study of natural products. The isolated oleuropein (purity > 95%) was subsequently used for the estimation of its content in each extract with a simple, sensitive and accurate high-performance thin-layer chromatography method. The best fit calibration curve from 1.0 µg/track to 6.0 µg/track of oleuropein was polynomial and the quantification was achieved by UV detection at λ 240 nm. The method was validated giving rise to an efficient and high-throughput procedure, with the relative standard deviation % of repeatability and intermediate precision not exceeding 4.9% and accuracy between 92% and 98% (recovery rates). Moreover, the method was validated for robustness, limit of quantitation, and limit of detection. The amount of oleuropein for OLE_A, OLE_AA, and an aqueous extract of olive leaves was estimated to be 35.5% ± 2.7, 51.5% ± 1.4, and 12.5% ± 0.12, respectively. Statistical analysis proved that the method is repeatable and selective, and can be effectively applied for the estimation of oleuropein in olive leaves' extracts, and could potentially replace high-performance liquid chromatography methodologies developed so far. Thus, the phytochemical investigation of oleuropein could be based on high-performance thin-layer chromatography coupled with separation processes, such as fast centrifugal partition chromatography, showing efficacy and credibility. Georg Thieme Verlag KG Stuttgart · New York.

Development and Validation of High-performance Thin Layer Chromatographic Method for Ursolic Acid in Malus domestica Peel

PubMed Central

Nikam, P. H.; Kareparamban, J. A.; Jadhav, A. P.; Kadam, V. J.

2013-01-01

Ursolic acid, a pentacyclic triterpenoid possess a wide range of pharmacological activities. It shows hypoglycemic, antiandrogenic, antibacterial, antiinflammatory, antioxidant, diuretic and cynogenic activity. It is commonly present in plants especially coating of leaves and fruits, such as apple fruit, vinca leaves, rosemary leaves, and eucalyptus leaves. A simple high-performance thin layer chromatographic method has been developed for the quantification of ursolic acid from apple peel (Malus domestica). The samples dissolved in methanol and linear ascending development was carried out in twin trough glass chamber. The mobile phase was selected as toluene:ethyl acetate:glacial acetic acid (70:30:2). The linear regression analysis data for the calibration plots showed good linear relationship with r2=0.9982 in the concentration range 0.2-7 μg/spot with respect to peak area. According to the ICH guidelines the method was validated for linearity, accuracy, precision, and robustness. Statistical analysis of the data showed that the method is reproducible and selective for the estimation of ursolic acid. PMID:24302805

Inactivation of aflatoxin B1 by using the synergistic effect of hydrogen peroxide and gamma radiation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Patel, U.D.; Govindarajan, P.; Dave, P.J.

Inactivation of aflatoxin B1 was studied by using gamma radiation and hydrogen peroxide. A 100-krad dose of gamma radiation was sufficient to inactivate 50 micrograms of aflatoxin B1 in the presence of 5% hydrogen peroxide, and 400 krad was required for total degradation of 100 micrograms of aflatoxin in the same system. Degradation of aflatoxin B1 was confirmed by high-pressure liquid chromatographic and thin-layer chromatographic analysis. Ames microsomal mutagenicity test showed loss of aflatoxin activity. This method of detoxification also reduces the toxin levels effectively in artificially contaminated groundnuts.

Thin layer chromatographic method for the detection of uric acid: collaborative study.

PubMed

Thrasher, J J; Abadie, A

1978-07-01

A collaborative study has been completed on an improved method for the detection and confirmation of uric acid from bird and insect excreta. The proposed method involves the lithium carbonate solubilization of the suspect excreta material, followed by butanol-methanol-water-acetic acid thin layer chromatography, and trisodium phosphate-phosphotungstic acid color development. The collaborative tests resulted in 100% detection of uric acid standard at the 50 ng level and 75% detection at the 20-25 ng level. No false positives were reported during tests of compounds similar to uric acid. The proposed method has been adopted official first action; the present official final action method, 44.161, will be retained for screening purposes.

High-performance Thin-layer Chromatographic-densitometric Quantification and Recovery of Bioactive Compounds for Identification of Elite Chemotypes of Gloriosa superba L. Collected from Sikkim Himalayas (India)

PubMed Central

Misra, Ankita; Shukla, Pushpendra Kumar; Kumar, Bhanu; Chand, Jai; Kushwaha, Poonam; Khalid, Md.; Singh Rawat, Ajay Kumar; Srivastava, Sharad

2017-01-01

Background: Gloriosa superba L. (Colchicaceae) is used as adjuvant therapy in gout for its potential antimitotic activity due to high colchicine(s) alkaloids. Objective: This study aimed to develop an easy, cheap, precise, and accurate high-performance thin-layer chromatographic (HPTLC) validated method for simultaneous quantification of bioactive alkaloids (colchicine and gloriosine) in G. superba L. and to identify its elite chemotype(s) from Sikkim Himalayas (India). Methods: The HPTLC chromatographic method was developed using mobile phase of chloroform: acetone: diethyl amine (5:4:1) at λmax of 350 nm. Results: Five germplasms were collected from targeted region, and on morpho-anatomical inspection, no significant variation was observed among them. Quantification data reveal that content of colchicine (Rf: 0.72) and gloriosine (Rf: 0.61) varies from 0.035%–0.150% to 0.006%–0.032% (dry wt. basis). Linearity of method was obtained in the concentration range of 100–400 ng/spot of marker(s), exhibiting regression coefficient of 0.9987 (colchicine) and 0.9983 (gloriosine) with optimum recovery of 97.79 ± 3.86 and 100.023% ± 0.01%, respectively. Limit of detection and limit of quantification were analyzed, respectively, as 6.245, 18.926 and 8.024, 24.316 (ng). Two germplasms, namely NBG-27 and NBG-26, were found to be elite chemotype of both the markers. Conclusion: The developed method is validated in terms of accuracy, recovery, and precision studies as per the ICH guidelines (2005) and can be adopted for the simultaneous quantification of colchicine and gloriosine in phytopharmaceuticals. In addition, this study is relevant to explore the chemotypic variability in metabolite content for commercial and medicinal purposes. SUMMARY An easy, cheap, precise, and accurate high performance thin layer chromatographic (HPTLC) validated method for simultaneous quantification of bioactive alkaloids (colchicine and gloriosine) in G. superba L.Five germplasms were collected from targeted region, and on morpho anatomical inspection, no significant variation was observed among themQuantification data reveal that content of colchicine (Rf: 0.72) and gloriosine (Rf: 0.61) varies from 0.035%–0.150% to 0.006%–0.032% (dry wt. basis)Two germplasms, namely NBG 27 and NBG 26, were found to be elite chemotype of both the markers. PMID:29142436

High-performance Thin-layer Chromatographic-densitometric Quantification and Recovery of Bioactive Compounds for Identification of Elite Chemotypes of Gloriosa superba L. Collected from Sikkim Himalayas (India).

PubMed

Misra, Ankita; Shukla, Pushpendra Kumar; Kumar, Bhanu; Chand, Jai; Kushwaha, Poonam; Khalid, Md; Singh Rawat, Ajay Kumar; Srivastava, Sharad

2017-10-01

Gloriosa superba L. (Colchicaceae) is used as adjuvant therapy in gout for its potential antimitotic activity due to high colchicine(s) alkaloids. This study aimed to develop an easy, cheap, precise, and accurate high-performance thin-layer chromatographic (HPTLC) validated method for simultaneous quantification of bioactive alkaloids (colchicine and gloriosine) in G. superba L. and to identify its elite chemotype(s) from Sikkim Himalayas (India). The HPTLC chromatographic method was developed using mobile phase of chloroform: acetone: diethyl amine (5:4:1) at λ max of 350 nm. Five germplasms were collected from targeted region, and on morpho-anatomical inspection, no significant variation was observed among them. Quantification data reveal that content of colchicine ( R f : 0.72) and gloriosine ( R f : 0.61) varies from 0.035%-0.150% to 0.006%-0.032% (dry wt. basis). Linearity of method was obtained in the concentration range of 100-400 ng/spot of marker(s), exhibiting regression coefficient of 0.9987 (colchicine) and 0.9983 (gloriosine) with optimum recovery of 97.79 ± 3.86 and 100.023% ± 0.01%, respectively. Limit of detection and limit of quantification were analyzed, respectively, as 6.245, 18.926 and 8.024, 24.316 (ng). Two germplasms, namely NBG-27 and NBG-26, were found to be elite chemotype of both the markers. The developed method is validated in terms of accuracy, recovery, and precision studies as per the ICH guidelines (2005) and can be adopted for the simultaneous quantification of colchicine and gloriosine in phytopharmaceuticals. In addition, this study is relevant to explore the chemotypic variability in metabolite content for commercial and medicinal purposes. An easy, cheap, precise, and accurate high performance thin layer chromatographic (HPTLC) validated method for simultaneous quantification of bioactive alkaloids (colchicine and gloriosine) in G. superba L.Five germplasms were collected from targeted region, and on morpho anatomical inspection, no significant variation was observed among themQuantification data reveal that content of colchicine (Rf: 0.72) and gloriosine (Rf: 0.61) varies from 0.035%-0.150% to 0.006%-0.032% (dry wt. basis)Two germplasms, namely NBG 27 and NBG 26, were found to be elite chemotype of both the markers.

A new high-performance thin-layer chromatographic method for determining bile salt hydrolase activity.

PubMed

Rohawi, Nur Syakila; Ramasamy, Kalavathy; Agatonovic-Kustrin, Snezana; Lim, Siong Meng

2018-06-05

A quantitative assay using high-performance thin-layer chromatography (HPTLC) was developed to investigate bile salt hydrolase (BSH) activity in Pediococcus pentosaceus LAB6 and Lactobacillus plantarum LAB12 probiotic bacteria isolated from Malaysian fermented food. Lactic acid bacteria (LAB) were cultured in de Man Rogosa and Sharpe (MRS) broth containing 1 mmol/L of sodium-based glyco- and tauro-conjugated bile salts for 24 h. The cultures were centrifuged and the resultant cell free supernatant was subjected to chromatographic separation on a HPTLC plate. Conjugated bile salts were quantified by densitometric scans at 550 nm and results were compared to digital image analysis of chromatographic plates after derivatisation with anisaldehyde/sulfuric acid. Standard curves for bile salts determination with both methods show good linearity with high coefficient of determination (R 2 ) between 0.97 and 0.99. Method validation indicates good sensitivity with low relative standard deviation (RSD) (<10%), low limits of detection (LOD) of 0.4 versus 0.2 μg and limit of quantification (LOQ) of 1.4 versus 0.7 μg, for densitometric vs digital image analysis method, respectively. The bile salt hydrolase activity was found to be higher against glyco- than tauro-conjugated bile salts (LAB6; 100% vs >38%: LAB12; 100% vs >75%). The present findings strongly show that quantitative analysis via digitally-enhanced HPTLC offers a rapid quantitative analysis for deconjugation of bile salts by probiotics. Copyright © 2018. Published by Elsevier B.V.

Occurrence of psilocybin and psilocin in Psilocybe pseudobullacea (Petch) Pegler from the Venezuelan Andes.

PubMed

Marcano, V; Morales Méndez, A; Castellano, F; Salazar, F J; Martinez, L

1994-07-08

Using thin-layer chromatographic and spectroscopic (UV) methods two Psilocybe species from the Venezuelan Andes were analysed for the hallucinogens psilocybin and psilocin. These species are: P. montana (Pers. ex Fr.) Kumm and P. pseudobullacea (Petch) Pegler. Both hallucinogens were found in P. pseudobullacea, while P. montana was found to be exempt of these compounds.

Easy ambient sonic-spray ionization mass spectrometry combined with thin-layer chromatography.

PubMed

Haddad, Renato; Milagre, Humberto M S; Catharino, Rodrigo Ramos; Eberlin, Marcos N

2008-04-15

On-spot detection and analyte characterization on thin-layer chromatography (TLC) plates is performed via ambient desorption/ionization and (tandem) mass spectrometry detection, that is, via easy ambient sonic spray ionization mass spectrometry (EASI-MS). As proof-of-principle cases, mixtures of semipolar nitrogenated compounds as well as pharmaceutical drugs and vegetable oils have been tested. The technique has also been applied to monitor a chemical reaction of synthetic importance. EASI is the simplest and gentlest ambient ionization technique currently available, assisted solely by N2 (or air). It uses no voltages, no electrical discharges; no UV or laser beams, and no high temperature and is most easily implemented in all API mass spectrometers. TLC is also the simplest, fastest, and most easily performed chromatographic technique. TLC plus EASI-MS therefore provide a simple and advantageous combination of chromatographic separation and sensitive detection of the TLC spots as well as on-spot MS or MS/MS characterization. The favorable characteristics of TLC-EASI-MS indicate advantageous applications in several areas such as drug and oil analysis, phytochemistry and synthetic chemistry, forensics via reliable counterfeit detection, and quality control.

A 90-Day Oral Toxicity Study and a 5-Day Metabolism Study of Diisopropyl Methylphosphonate (DIMP) in Mink.

DTIC Science & Technology

1992-06-01

characterized with infrared and ultraviolet/visible spectroscopy , nuclear magnetic resonance analysis and gas and thin-layer chromatography. These...comparison gas chromatographic major peak profile of diisopropyl methylphosphonate. In brief, infrared and ultraviolet/visible spectroscopy and nuclear...An aliquot of this batch was analyzed by MRI, Kansas City, MO. The characterization consisted of determination of physical properties, spectroscopy

Simultaneous Quantification of Syringic Acid and Kaempferol in Extracts of Bergenia Species Using Validated High-Performance Thin-Layer Chromatographic-Densitometric Method.

PubMed

Srivastava, Nishi; Srivastava, Amit; Srivastava, Sharad; Rawat, Ajay Kumar Singh; Khan, Abdul Rahman

2016-03-01

A rapid, sensitive, selective and robust quantitative densitometric high-performance thin-layer chromatographic method was developed and validated for separation and quantification of syringic acid (SYA) and kaempferol (KML) in the hydrolyzed extracts of Bergenia ciliata and Bergenia stracheyi. The separation was performed on silica gel 60F254 high-performance thin-layer chromatography plates using toluene : ethyl acetate : formic acid (5 : 4: 1, v/v/v) as the mobile phase. The quantification of SYA and KML was carried out using a densitometric reflection/absorption mode at 290 nm. A dense spot of SYA and KML appeared on the developed plate at a retention factor value of 0.61 ± 0.02 and 0.70 ± 0.01. A precise and accurate quantification was performed using linear regression analysis by plotting the peak area vs concentration 100-600 ng/band (correlation coefficient: r = 0.997, regression coefficient: R(2) = 0.996) for SYA and 100-600 ng/band (correlation coefficient: r = 0.995, regression coefficient: R(2) = 0.991) for KML. The developed method was validated in terms of accuracy, recovery and inter- and intraday study as per International Conference on Harmonisation guidelines. The limit of detection and limit of quantification of SYA and KML were determined, respectively, as 91.63, 142.26 and 277.67, 431.09 ng. The statistical data analysis showed that the method is reproducible and selective for the estimation of SYA and KML in extracts of B. ciliata and B. stracheyi. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Thin layer chromatography residue applicator sampler

DOEpatents

Nunes, Peter J [Danville, CA; Kelly, Fredrick R [Modesto, CA; Haas, Jeffrey S [San Ramon, CA; Andresen, Brian D [Livermore, CA

2007-07-24

A thin layer chromatograph residue applicator sampler. The residue applicator sampler provides for rapid analysis of samples containing high explosives, chemical warfare, and other analyses of interest under field conditions. This satisfied the need for a field-deployable, small, hand-held, all-in-one device for efficient sampling, sample dissolution, and sample application to an analytical technique. The residue applicator sampler includes a sampling sponge that is resistant to most chemicals and is fastened via a plastic handle in a hermetically sealed tube containing a known amount of solvent. Upon use, the wetted sponge is removed from the sealed tube and used as a swiping device across an environmental sample. The sponge is then replaced in the hermetically sealed tube where the sample remains contained and dissolved in the solvent. A small pipette tip is removably contained in the hermetically sealed tube. The sponge is removed and placed into the pipette tip where a squeezing-out of the dissolved sample from the sponge into the pipette tip results in a droplet captured in a vial for later instrumental analysis, or applied directly to a thin layer chromatography plate for immediate analysis.

Development and Validation of a HPTLC Method for Simultaneous Estimation of L-Glutamic Acid and γ-Aminobutyric Acid in Mice Brain

PubMed Central

Sancheti, J. S.; Shaikh, M. F.; Khatwani, P. F.; Kulkarni, Savita R.; Sathaye, Sadhana

2013-01-01

A new robust, simple and economic high performance thin layer chromatographic method was developed for simultaneous estimation of L-glutamic acid and γ-amino butyric acid in brain homogenate. The high performance thin layer chromatographic separation of these amino acid was achieved using n-butanol:glacial acetic acid:water (22:3:5 v/v/v) as mobile phase and ninhydrin as a derivatising agent. Quantitation of the method was achieved by densitometric method at 550 nm over the concentration range of 10-100 ng/spot. This method showed good separation of amino acids in the brain homogenate with Rf value of L-glutamic acid and γ-amino butyric acid as 21.67±0.58 and 33.67±0.58, respectively. The limit of detection and limit of quantification for L-glutamic acid was found to be 10 and 20 ng and for γ-amino butyric acid it was 4 and 10 ng, respectively. The method was also validated in terms of accuracy, precision and repeatability. The developed method was found to be precise and accurate with good reproducibility and shows promising applicability for studying pathological status of disease and therapeutic significance of drug treatment. PMID:24591747

Development and Validation of a HPTLC Method for Simultaneous Estimation of L-Glutamic Acid and γ-Aminobutyric Acid in Mice Brain.

PubMed

Sancheti, J S; Shaikh, M F; Khatwani, P F; Kulkarni, Savita R; Sathaye, Sadhana

2013-11-01

A new robust, simple and economic high performance thin layer chromatographic method was developed for simultaneous estimation of L-glutamic acid and γ-amino butyric acid in brain homogenate. The high performance thin layer chromatographic separation of these amino acid was achieved using n-butanol:glacial acetic acid:water (22:3:5 v/v/v) as mobile phase and ninhydrin as a derivatising agent. Quantitation of the method was achieved by densitometric method at 550 nm over the concentration range of 10-100 ng/spot. This method showed good separation of amino acids in the brain homogenate with Rf value of L-glutamic acid and γ-amino butyric acid as 21.67±0.58 and 33.67±0.58, respectively. The limit of detection and limit of quantification for L-glutamic acid was found to be 10 and 20 ng and for γ-amino butyric acid it was 4 and 10 ng, respectively. The method was also validated in terms of accuracy, precision and repeatability. The developed method was found to be precise and accurate with good reproducibility and shows promising applicability for studying pathological status of disease and therapeutic significance of drug treatment.

Detection of structurally similar adulterants in botanical dietary supplements by thin-layer chromatography and surface enhanced Raman spectroscopy combined with two-dimensional correlation spectroscopy.

PubMed

Li, Hao; Zhu, Qing xia; Chwee, Tsz sian; Wu, Lin; Chai, Yi feng; Lu, Feng; Yuan, Yong fang

2015-07-09

Thin-layer chromatography (TLC) coupled with surface enhanced Raman spectroscopy (SERS) has been widely used for the study of various complex systems, especially for the detection of adulterants in botanical dietary supplements (BDS). However, this method is not sufficient to distinguish structurally similar adulterants in BDS since the analogs have highly similar chromatographic and/or spectroscopic behaviors. Taking into account the fact that higher cost and more time will be required for comprehensive chromatographic separation, more efforts with respect to spectroscopy are now focused on analyzing the overlapped SERS peaks. In this paper, the combination of a TLC-SERS method with two-dimensional correlation spectroscopy (2DCOS), with duration of exposure to laser as the perturbation, is applied to solve this problem. Besides the usual advantages of the TLC-SERS method, such as its simplicity, rapidness, and sensitivity, more advantages are presented here, such as enhanced selectivity and good reproducibility, which are obtained by 2DCOS. Two chemicals with similar structures are successfully differentiated from the complex BDS matrices. The study provides a more accurate qualitative screening method for detection of BDS with adulterants, and offers a new universal approach for the analysis of highly overlapped SERS peaks. Copyright © 2015 Elsevier B.V. All rights reserved.

Application of a newly developed and validated high-performance thin-layer chromatographic method to control honey adulteration.

PubMed

Puscas, Anitta; Hosu, Anamaria; Cimpoiu, Claudia

2013-01-11

Honey is a saturated solution of sugars, used for a long time as a natural source of sugars and is an important ingredient in traditional medicine due to its antimicrobial, anti-inflammatory and antioxidant effects. Therefore, methods for quality control of honey and detection of its adulteration are very important. For this reason, the aim of this study is to develop and validate a new, simple and economical analytical method for detecting the adulteration of some Romanian honeys based on high-performance thin-layer chromatography (HPTLC) combined with image analysis. The proposed method involved the chromatographic separations of glucose, fructose and sucrose on silica gel HPTLC plates, developed twice with ethyl acetate-pyridine-water-acetic acid, 6:3:1:0.5 (v/v/v/v), followed by dipping in an immersion solution. The documentation of plates was performed using TLC visualization device and the images of plates were processed using a digital processor. The developed HPTLC method was validated for selectivity, linearity and range, LOD and LOQ, precision, robustness and accuracy. The method was then applied for quantitative determination of glucose, fructose and sucrose from different types of Romanian honeys, commercially available. Copyright © 2012 Elsevier B.V. All rights reserved.

Chromatographic and electrophoretic approaches in ink analysis.

PubMed

Zlotnick, J A; Smith, F P

1999-10-15

Inks are manufactured from a wide variety of substances that exhibit very different chemical behaviors. Inks designed for use in different writing instruments or printing methods have quite dissimilar components. Since the 1950s chromatographic and electrophoretic methods have played important roles in the analysis of inks, where compositional information may have bearing on the investigation of counterfeiting, fraud, forgery, and other crimes. Techniques such as paper chromatography and electrophoresis, thin-layer chromatography, high-performance liquid chromatography, gas chromatography, gel electrophoresis, and the relatively new technique of capillary electrophoresis have all been explored as possible avenues for the separation of components of inks. This paper reviews the components of different types of inks and applications of the above separation methods are reviewed.

Lipophilicity of some guaianolides isolated from two endemic subspecies of Amphoricarpos neumayeri (Asteraceae) from Montenegro.

PubMed

Atrrog, Abubaker A B; Natić, Maja; Tosti, Tomislav; Milojković-Opsenica, Dusanka; Dordević, Iris; Tesević, Vele; Jadranin, Milka; Milosavljević, Slobodan; Lazić, Milan; Radulović, Sinisa; Tesić, Zivoslav

2009-03-01

In this study 10 guaianolide-type sesquiterpene gamma-lactones named amphoricarpolides, isolated from the aerial parts of two endemic subspecies of Amphoricarpos neumayeri (ssp. neumayeri and ssp. murbeckii Bosnjak), were investigated by means of reversed-phase thin-layer chromatography. Methanol-water and tetrahydrofuran-water binary mixtures were used as mobile phase in order to determine lipophilicity parameters R (0) (M) and C(0). Some of the investigated compounds were screened for their cytotoxic activity against HeLa and B16 cells. Chromatographically obtained lipophilicity parameters were correlated with calculated logP values and IC(50) values. Principal component analysis identified the dominant pattern in the chromatographically obtained data. 2008 John Wiley & Sons, Ltd.

Systematic Development and Validation of a Thin-Layer Densitometric Bioanalytical Method for Estimation of Mangiferin Employing Analytical Quality by Design (AQbD) Approach

PubMed Central

Khurana, Rajneet Kaur; Rao, Satish; Beg, Sarwar; Katare, O.P.; Singh, Bhupinder

2016-01-01

The present work aims at the systematic development of a simple, rapid and highly sensitive densitometry-based thin-layer chromatographic method for the quantification of mangiferin in bioanalytical samples. Initially, the quality target method profile was defined and critical analytical attributes (CAAs) earmarked, namely, retardation factor (Rf), peak height, capacity factor, theoretical plates and separation number. Face-centered cubic design was selected for optimization of volume loaded and plate dimensions as the critical method parameters selected from screening studies employing D-optimal and Plackett–Burman design studies, followed by evaluating their effect on the CAAs. The mobile phase containing a mixture of ethyl acetate : acetic acid : formic acid : water in a 7 : 1 : 1 : 1 (v/v/v/v) ratio was finally selected as the optimized solvent for apt chromatographic separation of mangiferin at 262 nm with Rf 0.68 ± 0.02 and all other parameters within the acceptance limits. Method validation studies revealed high linearity in the concentration range of 50–800 ng/band for mangiferin. The developed method showed high accuracy, precision, ruggedness, robustness, specificity, sensitivity, selectivity and recovery. In a nutshell, the bioanalytical method for analysis of mangiferin in plasma revealed the presence of well-resolved peaks and high recovery of mangiferin. PMID:26912808

HPTLC and magnetochromatography of new complexes of carboxylates with transition metals or rare earth elements and their ligands - study of lipophilicity.

PubMed

Malinowska, Irena; Wronka, Agnieszka; Ferenc, Wiesława

2017-05-01

Nineteen new complexes of carboxylates with transition and rare elements as central ions and their ligands were characterized by chromatographic analyses. The parameter of relative lipophilicity (R M0 ) of the tested compounds was determined experimentally by the reversed-phase high-performance thin layer chromatography method with mixtures of various organic modifiers (acetonitrile, acetone, dioxane) and water as a mobile phase. The extrapolated R M0 values were compared with the logP values calculated from the molecular structures of tested solutes. Similarities between the lipophilicity indices were analysed by principal component analysis and linear regression. Thin-layer chromatography combined with a magnetic field has been proposed as a complementary method for determination of lipophilicity of the investigated compounds. The chromatograms in the field and outside it were developed simultaneously in two identical chromatographic chambers. One of them was placed in the external magnetic field of 0.4 T inductivity. We proved that chelation causes a drastic change in compound lipophilicity, but all complexes did not exhibit enhanced activity as compared with the parent ligand. Also in the magnetic field the retention of some complexes changed, which means that the presence of the field influences the physicochemical properties of the compounds and their interactions with the stationary phase. Copyright © 2016 John Wiley & Sons, Ltd.

The experimental design approach to eluotropic strength of 20 solvents in thin-layer chromatography on silica gel.

PubMed

Komsta, Łukasz; Stępkowska, Barbara; Skibiński, Robert

2017-02-03

The eluotropic strength on thin-layer silica plates was investigated for 20 chromatographic grade solvents available in current market. 35 model compounds were used as test subjects in the investigation. The use of modern mixture screening design allowed to estimate each solvent as a separate elution coefficient with an acceptable error of estimation (0.0913 of R M value). Additional bootstrapping technique was used to check the distribution and uncertainty of eluotropic estimates, proving very similar confidence intervals to linear regression. Principal component analysis proved that the only one parameter (mean eluotropic strength) is satisfactory to describe the solvent property, as it explains almost 90% of variance of retention. The obtained eluotropic data can be good appendix to earlier published results and their values can be interpreted in context of R M differences. Copyright © 2017 Elsevier B.V. All rights reserved.

The experimental design approach to eluotropic strength of 20 solvents in thin-layer chromatography on silica gel.

PubMed

Komsta, Łukasz; Stępkowska, Barbara; Skibiński, Robert

2017-01-04

The eluotropic strength on thin-layer silica plates was investigated for 20 chromatographic grade solvents available in current market. 35 model compounds were used as test subjects in the investigation. The use of modern mixture screening design allowed to estimate each solvent as a separate elution coefficient with an acceptable error of estimation (0.0913 of R M value). Additional bootstrapping technique was used to check the distribution and uncertainty of eluotropic estimates, proving very similar confidence intervals to linear regression. Principal component analysis proved that the only one parameter (mean eluotropic strength) is satisfactory to describe the solvent property, as it explains almost 90% of variance of retention. The obtained eluotropic data can be good appendix to earlier published results and their values can be interpreted in context of R M differences. Copyright © 2017 Elsevier B.V. All rights reserved.

Densitometric thin-layer chromatographic determination of aescin in a herbal medicinal product containing Aesculus and Vitis dry extracts.

PubMed

Apers, Sandra; Naessens, Tania; Pieters, Luc; Vlietinck, Arnold

2006-04-21

A thin-layer chromatographic (TLC) method is developed to analyze the total saponin content, also referred to as the aescin content, in a herbal medicinal product (HMP) containing two dry extracts in capsules. The capsules contain 250 mg of Aesculus hippocastanum dry extract, 120 mg of Vitis vinifera dry extract and 50mg of excipients. After a purification step using C(18) solid phase extraction (SPE) cartridges, the samples are analyzed on a silica-gel HPTLC plate with the upper layer of a mixture of acetic acid/water/butanol (10/40/50 v/v/v) as the mobile phase. Spots are visualized by spraying with anisaldehyde reagent and heating the plate for 5-10 min (100-105 degrees C) and measured at a wavelength of 535 nm. This method, applicable for the quality control and stability investigation of both the Aesculus dry extract and HMP capsules thereof containing Vitis dry extract in combination with the Aesculus dry extract, is validated according to the International Conference on Harmonization (ICH) guidelines. The proposed assay method is specific for aescin in the presence of Vitis dry extract and formulation excipients. Analysis of stressed samples in forced degradation tests proves the method to be applicable for stability evaluation. The standard aescin curve is linear (r > 0.99) over a concentration range of 0.16-0.80 microg/spot. Recovery from the HMP capsules is statistically equal to 100%. The precision of the method with respect to time and concentration is acceptable, with relative standard deviation (RSD) values of 1.28 and 1.49%, respectively.

The characterization and properties of castaprenol-11, -12 and -13 from the leaves of Aesculus hippocastanum (horse chestnut)

PubMed Central

Wellburn, A. R.; Stevenson, J.; Hemming, F. W.; Morton, R. A.

1967-01-01

The isolation and purification of a mixture of cis–trans-polyprenols from the leaves of Aesculus hippocastanum (horse chestnut) are described. Results of studies involving mass spectrometry, nuclear magnetic resonance, infrared spectroscopy, micro-hydrogenation and ozonolytic degradation show the mixture to be made up of undecaprenol, dodecaprenol and tridecaprenol with dodecaprenol predominating. Each of the prenols contains three trans internal isoprene residues and a cis `OH-terminal' isoprene residue. They differ from each other only in the number of cis internal isoprene residues. The trivial names castaprenol-11, castaprenol-12 and castaprenol-13 are proposed to describe these compounds. Gas–liquid-chromatographic and reversed-phase partition thin-layer chromatographic evidence suggest the presence in the mixture of small quantities of castaprenol-10 also. PMID:6067665

Lipidomics in triacylglycerol and cholesteryl ester oxidation.

PubMed

Kuksis, Arnis

2007-05-01

Although direct mass spectrometry is capable of identification the major molecular species of lipids in crude total lipid extracts, prior chromatographic isolation is necessary for detection and identification of the minor components. This is especially important for the analysis of the oxolipids, which usually occur in trace amounts in the total lipid extract, and require prior isolation for detailed analysis. Both thin-layer chromatography and adsorption cartridges provide effective means for isolation and enrichment of lipid classes, while gas-liquid chromatography and high performance liquid chromatography with on-line mass spectrometry permit further separation and identification of molecular species. Prior chromatographic resolution is absolutely necessary for the identification of isobaric and chiral molecules, which mass spectrometry/mass spectrometry (MS/MS) cannot distinguish. Both gas chromatography-mass spectrometry and liquid chromatography-mass spectrometry applications may require the preparation of derivatives in order to improve the chromatographic and mass spectrometric properties of the oxolipids which is a small inconvenience for securing analytical reliability. The following chapter reviews the advantages and necessity of combined chromatographic-mass spectrometric approaches to successful identification and quantification of molecular species of oxoacylglycerols and oxocholesteryl esters in in-vitro model studies of lipid peroxidation and in the analyses of oxolipids recovered from tissues.

Combined liquid chromatography-mass spectrometry for trace analysis of pharmaceuticals

NASA Astrophysics Data System (ADS)

Schmidt, Lothar; Danigel, Harald; Jungclas, Hartmut

1982-07-01

A 252Cf-plasma desorption mass spectrometer (PDMS) for the analysis of thin layers from nonvolatile organic samples has been set up to be combined with a liquid chromatograph. A novel interface performs the direct inlet of the liquid sample through a capillary into the vacuum system of the spectrometer. Samples of drugs are periodically collected, transferred to the ion source and analysed using a rotating disk. This on-line sample preparation has been tested for three antiarrhythmic drugs using various solvents and mixtures.

Liquid Crystals in Chromatography

NASA Astrophysics Data System (ADS)

Witkiewicz, Zygfryd

The following sections are included: * INTRODUCTION * LIQUID CRYSTALS SUITABLE FOR GAS CHROMATOGRAPHY * Monomeric Liquid Crystal Stationary Phases * Polymeric Liquid Crystal Stationary Phases * Polymeric Liquid Crystal Stationary Phases * Conventional Analytical Columns * Capillary Columns * FACTORS AFFECTING THE CHROMATOGRAPHIC SEPARATIONS ON LIQUID CRYSTAL STATIONARY PHASES * Kind of Mesophase of the Liquid Crystal * Molecular Structure of the Liquid Crystals and of the Chromatographed Substances * Substrate on which the Liquid Crystal is Deposited * ANALYTICAL APPLICATIONS OF LIQUID CRYSTAL STATIONARY PHASES IN GAS CHROMATOGRAPHY * Separation of Isomers of Benzene and Naphthalene Derivatives * Separation of Alkane and Alkene Isomers * Separation of Mixtures of Benzene and Aliphatic Hydrocarbon Derivatives Containing Heteroatoms * Separation of Polynuclear Hydrocarbons * INVESTIGATION OF THE PROPERTIES OF LIQUID CRYSTALS BY GAS CHROMATOGRAPHY * APPLICATION OF LIQUID CRYSTALS IN LIQUID CHROMATOGRAPHY * Column Chromatography * Thin-Layer Chromatography * APPLICATION OF LIQUID CRYSTAL STATIONARY PHASES IN SUPERCRITICAL FLUID CHROMATOGRAPHY * FINAL REMARKS * References

Nanoscale pillar arrays for separations

DOE PAGES

Kirchner, Teresa; Strickhouser, Rachel; Hatab, Nahla; ...

2015-04-01

The work presented herein evaluates silicon nano-pillar arrays for use in planar chromatography. Electron beam lithography and metal thermal dewetting protocols were used to create nano-thin layer chromatography platforms. With these fabrication methods we are able to reduce the size of the characteristic features in a separation medium below that used in ultra-thin layer chromatography; i.e. pillar heights are 1-2μm and pillar diameters are typically in the 200- 400nm range. In addition to the intrinsic nanoscale aspects of the systems, it is shown they can be further functionalized with nanoporous layers and traditional stationary phases for chromatography; hence exhibit broad-rangingmore » lab-on-a-chip and point-of-care potential. Because of an inherent high permeability and very small effective mass transfer distance between pillars, chromatographic efficiency can be very high but is enhanced herein by stacking during development and focusing while drying, yielding plate heights in the nm range separated band volumes. Practical separations of fluorescent dyes, fluorescently derivatized amines, and anti-tumor drugs are illustrated.« less

Combining simplicity with cost-effectiveness: Investigation of potential counterfeit of proton pump inhibitors through simulated formulations using thin-layer chromatography.

PubMed

Bhatt, Nejal M; Chavada, Vijay D; Sanyal, Mallika; Shrivastav, Pranav S

2016-11-18

A simple, accurate and precise high-performance thin-layer chromatographic method has been developed and validated for the analysis of proton pump inhibitors (PPIs) and their co-formulated drugs, available as binary combination. Planar chromatographic separation was achieved using a single mobile phase comprising of toluene: iso-propranol: acetone: ammonia 5.0:2.3:2.5:0.2 (v/v/v/v) for the analysis of 14 analytes on aluminium-backed layer of silica gel 60 FG 254 . Densitometric determination of the separated spots was done at 290nm. The method was validated according to ICH guidelines for linearity, precision and accuracy, sensitivity, specificity and robustness. The method showed good linear response for the selected drugs as indicated by the high values of correlation coefficients (≥0.9993). The limit of detection and limit of quantiation were in the range of 6.9-159.2ng/band and 20.8-478.1ng/band respectively for all the analytes. The optimized conditions afforded adequate resolution of each PPI from their co-formulated drugs and provided unambiguous identification of the co-formulated drugs from their homologous retardation factors (hR f ). The only limitation of the method was the inability to separate two PPIs, rabeprazole and lansoprazole from each other. Nevertheless, it is proposed that peak spectra recording and comparison with standard drug spot can be a viable option for assignment of TLC spots. The method performance was assessed by analyzing different laboratory simulated mixtures and some marketed formulations of the selected drugs. The developed method was successfully used to investigate potential counterfeit of PPIs through a series of simulated formulations with good accuracy and precision. Copyright © 2016 Elsevier B.V. All rights reserved.

High-performance thin-layer chromatographic methods in the evaluation of the antioxidant and anti-hyperglycemic activity of Myrmecodia platytyrea as a promising opportunity in diabetes treatment.

PubMed

Agatonovic-Kustrin, S; Morton, D W; Adam, A; Mizaton, H H; Zakaria, H

2017-12-29

The steady increase of diabetes is becoming a major burden on health care systems. As diabetic complications arise from oxidative stress, an antioxidant therapy along with anti-diabetic drugs is recommended. Myrmecodia or ant plant is highly valued as a traditional medicine in West Papua. It is used as an alternative treatment for diabetes, as the substances produced by ants can reduce blood sugar levels. The aim of this study was to develop and establish high-performance thin-layer chromatographic (HPTLC)-bioautographic methods to measure the antioxidant and hypoglycemic effects in different extracts from Myrmecodia platytyrea and to compare them with sterol content. Antioxidant activity in methanol, ethanol, dichloromethane (DCM) and ethyl acetate (EA) extracts were measured with a direct HPTLC-2,2-diphenyl-1-picrylhydrazyl free radical (DPPH) assay, while hypoglycemic effects were assessed using a newly developed α-amylase inhibitory activity assay. Stigmasterol is observed, after derivatization with anisaldehyde, as purple colored zones under visible light at hRF values of 0.66. The highest antioxidant activity was observed in the ethanol extract which is rich in polyphenols and flavonoids, while the DCM extract did not show antioxidant activity, but had significant α-amylase inhibitory activity. The highest α-amylase inhibitory activity was observed in the EA and DCM extracts and was related to their stigmasterol content. Crown Copyright © 2017. Published by Elsevier B.V. All rights reserved.

Thin-layer chromatographic identification of Chinese propolis using chemometric fingerprinting.

PubMed

Tang, Tie-xin; Guo, Wei-yan; Xu, Ye; Zhang, Si-ming; Xu, Xin-jun; Wang, Dong-mei; Zhao, Zhi-min; Zhu, Long-ping; Yang, De-po

2014-01-01

Poplar tree gum has a similar chemical composition and appearance to Chinese propolis (bee glue) and has been widely used as a counterfeit propolis because Chinese propolis is typically the poplar-type propolis, the chemical composition of which is determined mainly by the resin of poplar trees. The discrimination of Chinese propolis from poplar tree gum is a challenging task. To develop a rapid thin-layer chromatographic (TLC) identification method using chemometric fingerprinting to discriminate Chinese propolis from poplar tree gum. A new TLC method using a combination of ammonia and hydrogen peroxide vapours as the visualisation reagent was developed to characterise the chemical profile of Chinese propolis. Three separate people performed TLC on eight Chinese propolis samples and three poplar tree gum samples of varying origins. Five chemometric methods, including similarity analysis, hierarchical clustering, k-means clustering, neural network and support vector machine, were compared for use in classifying the samples based on their densitograms obtained from the TLC chromatograms via image analysis. Hierarchical clustering, neural network and support vector machine analyses achieved a correct classification rate of 100% in classifying the samples. A strategy for TLC identification of Chinese propolis using chemometric fingerprinting was proposed and it provided accurate sample classification. The study has shown that the TLC identification method using chemometric fingerprinting is a rapid, low-cost method for the discrimination of Chinese propolis from poplar tree gum and may be used for the quality control of Chinese propolis. Copyright © 2014 John Wiley & Sons, Ltd.

Stability indicating high performance thin-layer chromatographic method for simultaneous estimation of pantoprazole sodium and itopride hydrochloride in combined dosage form

PubMed Central

Bageshwar, Deepak; Khanvilkar, Vineeta; Kadam, Vilasrao

2011-01-01

A specific, precise and stability indicating high-performance thin-layer chromatographic method for simultaneous estimation of pantoprazole sodium and itopride hydrochloride in pharmaceutical formulations was developed and validated. The method employed TLC aluminium plates precoated with silica gel 60F254 as the stationary phase. The solvent system consisted of methanol:water:ammonium acetate; 4.0:1.0:0.5 (v/v/v). This system was found to give compact and dense spots for both itopride hydrochloride (Rf value of 0.55±0.02) and pantoprazole sodium (Rf value of 0.85±0.04). Densitometric analysis of both drugs was carried out in the reflectance–absorbance mode at 289 nm. The linear regression analysis data for the calibration plots showed a good linear relationship with R2=0.9988±0.0012 in the concentration range of 100–400 ng for pantoprazole sodium. Also, the linear regression analysis data for the calibration plots showed a good linear relationship with R2=0.9990±0.0008 in the concentration range of 200–1200 ng for itopride hydrochloride. The method was validated for specificity, precision, robustness and recovery. Statistical analysis proves that the method is repeatable and selective for the estimation of both the said drugs. As the method could effectively separate the drug from its degradation products, it can be employed as a stability indicating method. PMID:29403710

Stability indicating high performance thin-layer chromatographic method for simultaneous estimation of pantoprazole sodium and itopride hydrochloride in combined dosage form.

PubMed

Bageshwar, Deepak; Khanvilkar, Vineeta; Kadam, Vilasrao

2011-11-01

A specific, precise and stability indicating high-performance thin-layer chromatographic method for simultaneous estimation of pantoprazole sodium and itopride hydrochloride in pharmaceutical formulations was developed and validated. The method employed TLC aluminium plates precoated with silica gel 60F 254 as the stationary phase. The solvent system consisted of methanol:water:ammonium acetate; 4.0:1.0:0.5 (v/v/v). This system was found to give compact and dense spots for both itopride hydrochloride ( R f value of 0.55±0.02) and pantoprazole sodium ( R f value of 0.85±0.04). Densitometric analysis of both drugs was carried out in the reflectance-absorbance mode at 289 nm. The linear regression analysis data for the calibration plots showed a good linear relationship with R 2 =0.9988±0.0012 in the concentration range of 100-400 ng for pantoprazole sodium. Also, the linear regression analysis data for the calibration plots showed a good linear relationship with R 2 =0.9990±0.0008 in the concentration range of 200-1200 ng for itopride hydrochloride. The method was validated for specificity, precision, robustness and recovery. Statistical analysis proves that the method is repeatable and selective for the estimation of both the said drugs. As the method could effectively separate the drug from its degradation products, it can be employed as a stability indicating method.

Systematic Development and Validation of a Thin-Layer Densitometric Bioanalytical Method for Estimation of Mangiferin Employing Analytical Quality by Design (AQbD) Approach.

PubMed

Khurana, Rajneet Kaur; Rao, Satish; Beg, Sarwar; Katare, O P; Singh, Bhupinder

2016-01-01

The present work aims at the systematic development of a simple, rapid and highly sensitive densitometry-based thin-layer chromatographic method for the quantification of mangiferin in bioanalytical samples. Initially, the quality target method profile was defined and critical analytical attributes (CAAs) earmarked, namely, retardation factor (Rf), peak height, capacity factor, theoretical plates and separation number. Face-centered cubic design was selected for optimization of volume loaded and plate dimensions as the critical method parameters selected from screening studies employing D-optimal and Plackett-Burman design studies, followed by evaluating their effect on the CAAs. The mobile phase containing a mixture of ethyl acetate : acetic acid : formic acid : water in a 7 : 1 : 1 : 1 (v/v/v/v) ratio was finally selected as the optimized solvent for apt chromatographic separation of mangiferin at 262 nm withRf 0.68 ± 0.02 and all other parameters within the acceptance limits. Method validation studies revealed high linearity in the concentration range of 50-800 ng/band for mangiferin. The developed method showed high accuracy, precision, ruggedness, robustness, specificity, sensitivity, selectivity and recovery. In a nutshell, the bioanalytical method for analysis of mangiferin in plasma revealed the presence of well-resolved peaks and high recovery of mangiferin. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Quantification of Quercetin and Rutin from Benincasa hispida Seeds and Carissa Congesta Roots by High-performance Thin Layer Chromatography and High-performance Liquid Chromatography.

PubMed

Doshi, Gaurav Mahesh; Une, Hemant Devidas

2016-01-01

In Indian Ayurvedic system, Benincasa hispida (BH) and Carissa congesta (CC) are well-known plants used for major and minor ailments. BH has been regarded as Kushmanda, whereas CC has been used in immune-related disorders of the human system. Quercetin and rutin identified from the vast plethora of plant extracts have proved to possess ethnopharmacological relevance. In present studies, we have determined quercetin and rutin in terms of percentage in BH seeds and CC roots by high-performance thin layer chromatography (HPTLC) and high-performance liquid chromatography (HPLC). After extraction and phytochemical screening, the extracts were subjected to quantification for the presence of quercetin and rutin by HPTLC and HPLC. HPTLC showed quercetin as 44.60, 27.13% and rutin as 32.00, 36.31% w/w, whereas HPLC revealed quercetin as 34.00, 35.00% and rutin as 21.99, 45.03% w/v in BH and CC extracts, respectively. The BH and CC extracts have elucidated peaks that were corresponding with standard peaks on undertaking chromatographic studies. Quercetin and rutin are isolated from BH seeds and CC roots by High Performance. Thin Layer Chromatography and High Performance Liquid Chromatography. HPTLC revealed presence of quercetin as 44.60, 27.13 % and rutin as 32.00, 36.31 % w/w. HPLC revealed presence of quercetin as 34.00, 35.00 % and rutin as 21.99, 45.03 % w/v. Abbreviation Used: HPTLC: High Performance Thin Layer Chromatography; HPLC: High Pressure Liquid Chromatography, UV: Ultraviolet, CC: Carissa congesta, BH: Benincasa hispida.

A validated high performance thin layer chromatography method for determination of yohimbine hydrochloride in pharmaceutical preparations

PubMed Central

Badr, Jihan M.

2013-01-01

Background: Yohimbine is an indole alkaloid used as a promising therapy for erectile dysfunction. A number of methods were reported for the analysis of yohimbine in the bark or in pharmaceutical preparations. Materials and Method: In the present work, a simple and sensitive high performance thin layer chromatographic method is developed for determination of yohimbine (occurring as yohimbine hydrochloride) in pharmaceutical preparations and validated according to International Conference of Harmonization (ICH) guidelines. The method employed thin layer chromatography aluminum sheets precoated with silica gel as the stationary phase and the mobile phase consisted of chloroform:methanol:ammonia (97:3:0.2), which gave compact bands of yohimbine hydrochloride. Results: Linear regression data for the calibration curves of standard yohimbine hydrochloride showed a good linear relationship over a concentration range of 80–1000 ng/spot with respect to the area and correlation coefficient (R2) was 0.9965. The method was evaluated regarding accuracy, precision, selectivity, and robustness. Limits of detection and quantitation were recorded as 5 and 40 ng/spot, respectively. The proposed method efficiently separated yohimbine hydrochloride from other components even in complex mixture containing powdered plants. The amount of yohimbine hydrochloride ranged from 2.3 to 5.2 mg/tablet or capsule in preparations containing the pure alkaloid, while it varied from zero (0) to 1.5–1.8 mg/capsule in dietary supplements containing powdered yohimbe bark. Conclusion: We concluded that this method employing high performance thin layer chromatography (HPTLC) in quantitative determination of yohimbine hydrochloride in pharmaceutical preparations is efficient, simple, accurate, and validated. PMID:23661986

A validated high performance thin layer chromatography method for determination of yohimbine hydrochloride in pharmaceutical preparations.

PubMed

Badr, Jihan M

2013-01-01

Yohimbine is an indole alkaloid used as a promising therapy for erectile dysfunction. A number of methods were reported for the analysis of yohimbine in the bark or in pharmaceutical preparations. In the present work, a simple and sensitive high performance thin layer chromatographic method is developed for determination of yohimbine (occurring as yohimbine hydrochloride) in pharmaceutical preparations and validated according to International Conference of Harmonization (ICH) guidelines. The method employed thin layer chromatography aluminum sheets precoated with silica gel as the stationary phase and the mobile phase consisted of chloroform:methanol:ammonia (97:3:0.2), which gave compact bands of yohimbine hydrochloride. Linear regression data for the calibration curves of standard yohimbine hydrochloride showed a good linear relationship over a concentration range of 80-1000 ng/spot with respect to the area and correlation coefficient (R(2)) was 0.9965. The method was evaluated regarding accuracy, precision, selectivity, and robustness. Limits of detection and quantitation were recorded as 5 and 40 ng/spot, respectively. The proposed method efficiently separated yohimbine hydrochloride from other components even in complex mixture containing powdered plants. The amount of yohimbine hydrochloride ranged from 2.3 to 5.2 mg/tablet or capsule in preparations containing the pure alkaloid, while it varied from zero (0) to 1.5-1.8 mg/capsule in dietary supplements containing powdered yohimbe bark. We concluded that this method employing high performance thin layer chromatography (HPTLC) in quantitative determination of yohimbine hydrochloride in pharmaceutical preparations is efficient, simple, accurate, and validated.

Development and validation of a normal-phase high-performance thin layer chromatographic method for the analysis of sulfamethoxazole and trimethoprim in co-trimoxazole tablets.

PubMed

Shewiyo, D H; Kaale, E; Risha, P G; Dejaegher, B; Smeyers-Verbeke, J; Vander Heyden, Y

2009-10-16

Pneumocystis carinii pneumonia (PCP) is often the ultimate mortal cause for immunocompromised individuals, such as HIV/AIDS patients. Currently, the most effective medicine for treatment and prophylaxis is co-trimoxazole, a synergistic combination of sulfamethoxazole (SMX) and trimethoprim (TMP). In order to ensure a continued availability of high quality co-trimoxazole tablets within resource-limited countries, Medicines Regulatory Authorities must perform quality control of these products. However, most pharmacopoeial methods are based on high-performance liquid chromatographic (HPLC) methods. Because of the lack of equipment, the Tanzania Food and Drugs Authority (TFDA) laboratory decided to develop and validate an alternative method of analysis based on the TLC technique with densitometric detection, for the routine quality control of co-trimoxazole tablets. SMX and TMP were separated on glass-backed silica gel 60 F(254) plates in a high-performance thin layer chromatograph (HPTLC). The mobile phase was comprised of toluene, ethylacetate and methanol (50:28.5:21.5, v:v:v). Detection wavelength was 254 nm. The R(f) values were 0.30 and 0.61 for TMP and SMX, respectively. This method was validated for linearity, precision, trueness, specificity and robustness. Cochran's criterion test indicated homoscedasticity of variances for the calibration data. The F-tests for lack-of-fit indicated that straight lines were adequate to describe the relationship between spot areas and concentrations for each compound. The percentage relative standard deviations for repeatability and time-different precisions were 0.98 and 1.32, and 0.83 and 1.64 for SMX and TMP, respectively. Percentage recovery values were 99.00%+/-1.83 and 99.66%+/-1.21 for SMX and TMP, respectively. The method was found to be robust and was then successfully applied to analyze co-trimoxazole tablet samples.

Linear modeling of the soil-water partition coefficient normalized to organic carbon content by reversed-phase thin-layer chromatography.

PubMed

Andrić, Filip; Šegan, Sandra; Dramićanin, Aleksandra; Majstorović, Helena; Milojković-Opsenica, Dušanka

2016-08-05

Soil-water partition coefficient normalized to the organic carbon content (KOC) is one of the crucial properties influencing the fate of organic compounds in the environment. Chromatographic methods are well established alternative for direct sorption techniques used for KOC determination. The present work proposes reversed-phase thin-layer chromatography (RP-TLC) as a simpler, yet equally accurate method as officially recommended HPLC technique. Several TLC systems were studied including octadecyl-(RP18) and cyano-(CN) modified silica layers in combination with methanol-water and acetonitrile-water mixtures as mobile phases. In total 50 compounds of different molecular shape, size, and various ability to establish specific interactions were selected (phenols, beznodiazepines, triazine herbicides, and polyaromatic hydrocarbons). Calibration set of 29 compounds with known logKOC values determined by sorption experiments was used to build simple univariate calibrations, Principal Component Regression (PCR) and Partial Least Squares (PLS) models between logKOC and TLC retention parameters. Models exhibit good statistical performance, indicating that CN-layers contribute better to logKOC modeling than RP18-silica. The most promising TLC methods, officially recommended HPLC method, and four in silico estimation approaches have been compared by non-parametric Sum of Ranking Differences approach (SRD). The best estimations of logKOC values were achieved by simple univariate calibration of TLC retention data involving CN-silica layers and moderate content of methanol (40-50%v/v). They were ranked far well compared to the officially recommended HPLC method which was ranked in the middle. The worst estimates have been obtained from in silico computations based on octanol-water partition coefficient. Linear Solvation Energy Relationship study revealed that increased polarity of CN-layers over RP18 in combination with methanol-water mixtures is the key to better modeling of logKOC through significant diminishing of dipolar and proton accepting influence of the mobile phase as well as enhancing molar refractivity in excess of the chromatographic systems. Copyright © 2016 Elsevier B.V. All rights reserved.

Validation Thin Layer Chromatography for the Determination of Acetaminophen in Tablets and Comparison with a Pharmacopeial Method

PubMed Central

Pyka, Alina; Budzisz, Marika; Dołowy, Małgorzata

2013-01-01

Adsorption thin layer chromatography (NP-TLC) with densitometry has been established for the identification and the quantification of acetaminophen in three leading commercial products of pharmaceutical tablets coded as brand: P1 (Product no. 1), P2 (Product no. 2), and P3 (Product no. 3). Applied chromatographic conditions have separated acetaminophen from its related substances, namely, 4-aminophenol and and 4′-chloroacetanilide. UV densitometry was performed in absorbance mode at 248 nm. The presented method was validated by specificity, range, linearity, accuracy, precision, detection limit, quantitative limit, and robustness. The TLC-densitometric method was also compared with a pharmacopeial UV-spectrophotometric method for the assay of acetaminophen, and the results confirmed statistically that the NP-TLC-densitometric method can be used as a substitute method. It could be said that the validated NP-TLC-densitometric method is suitable for the routine analysis of acetaminophen in quantity control laboratories. PMID:24063006

High Performance Thin layer Chromatography: Densitometry Method for Determination of Rubraxanthone in the Stem Bark Extract of Garcinia cowa Roxb.

PubMed

Hamidi, Dachriyanus; Aulia, Hilyatul; Susanti, Meri

2017-01-01

Garcinia cowa is a medicinal plant widely grown in Southeast Asia and tropical countries. Various parts of this plant have been used in traditional folk medicine. The bark, latex, and root have been used as an antipyretic agent, while fruit and leaves have been used as an expectorant, for indigestion and improvement of blood circulation. This study aims to determine the concentration of rubraxanthone found in ethyl acetate extract of the stem bark of G. cowa by the high-performance thin-layer chromatography (HPTLC). HPTLC method was performed on precoated silica gel G 60 F254 plates using an HPTLC system with a developed mobile-phase system of chloroform: ethyl acetate: methanol: formic acid (86:6:3:5). A volume of 5 μL of standard and sample solutions was applied to the chromatographic plates. The plates were developed in saturated mode of twin trough chamber at room temperature. The method was validated based on linearity, accuracy, precision, limit of detection (LOD), limit of quantification (LOQ), and specificity. The spots were observed at ultraviolet 243 nm. The linearity of rubraxanthone was obtained between 52.5 and 157.5 ppm/spot. The LOD and LOQ were found to be 4.03 and 13.42 ppm/spot, respectively. The proposed method showed good linearity, precision, accuracy, and high sensitivity. Therefore, it may be applied for the quantification of rubraxanthone in ethyl acetate extract of the stem bark of G. cowa . High performance thin layer chromatography (HPTLC) method provides rapid qualitative and quantitative estimation of rubraxanthone as a marker com¬pound in G. cowa extract used for commercial productRubraxanthone found in ethyl acetate extracts of G. cowa was successfully quantified using HPTLC method. Abbreviations Used : TLC: Thin-layer chromatography, HPTLC: High-performance thin-layer chromatography, LOD: Limit of detection, LOQ: Limit of quantification, ICH: International Conference on Harmonization.

Biotransformation and toxicity of aniline and aniline derivatives of cyanobacteria.

PubMed

Cerniglia, C E; Freeman, J P; Van Baalen, C

1981-12-01

Agmenellum quadruplicatum strain PR-6 and Oscillatoria sp. strain JCM grown photoautotrophically in the presence of aniline metabolized the aromatic amine to formanilide, acetanilide and p-aminophenol. The metabolites were isolated by either thin-layer, gas-liquid or high pressure liquid chromatography and identified by comparison of their chromatographic, ultraviolet absorbance and mass spectral properties with those of authentic compounds. The toxicity of aniline derivatives towards Agmenellum quadruplicatum strain PR-6 indicated that the cyanobacterium was extremely sensitive to o-, m- and p-aminophenols, and phenylhydroxylamine.

Simple TLC-screening of acylglycerol levels in biodiesel as an alternative to GC determination.

PubMed

Fontana, J D; Zagonel, G; Vechiatto, W W; Costa, B J; Laurindo, J C; Fontana, R; Pelisson, L; Jorge, B H; Lanças, F M

2009-10-01

Thin layer chromatography (TLC) stained with hot acidic p-anisaldehyde, is an interesting, fast, and low-cost technique to monitor main lipid contaminants such as triacylglycerols, diacylglycerols, and monoacylglycerols in biodiesel. These acylglycerols are detectable by the proposed planar chromatographic method, provided the content of the contaminants exceeds the limits recommended by the international norms applicable to biodiesel quality/specification, namely 0.25% in mass for total combined glycerin. The TLC data are confirmed by gas chromatography of the methyl esters of soy oil.

Quantification of Quercetin and Rutin from Benincasa hispida Seeds and Carissa Congesta Roots by High-performance Thin Layer Chromatography and High-performance Liquid Chromatography

PubMed Central

Doshi, Gaurav Mahesh; Une, Hemant Devidas

2016-01-01

Objective: In Indian Ayurvedic system, Benincasa hispida (BH) and Carissa congesta (CC) are well-known plants used for major and minor ailments. BH has been regarded as Kushmanda, whereas CC has been used in immune-related disorders of the human system. Quercetin and rutin identified from the vast plethora of plant extracts have proved to possess ethnopharmacological relevance. Materials and Methods: In present studies, we have determined quercetin and rutin in terms of percentage in BH seeds and CC roots by high-performance thin layer chromatography (HPTLC) and high-performance liquid chromatography (HPLC). After extraction and phytochemical screening, the extracts were subjected to quantification for the presence of quercetin and rutin by HPTLC and HPLC. Results: HPTLC showed quercetin as 44.60, 27.13% and rutin as 32.00, 36.31% w/w, whereas HPLC revealed quercetin as 34.00, 35.00% and rutin as 21.99, 45.03% w/v in BH and CC extracts, respectively. Conclusion: The BH and CC extracts have elucidated peaks that were corresponding with standard peaks on undertaking chromatographic studies. SUMMARY Quercetin and rutin are isolated from BH seeds and CC roots by High Performance. Thin Layer Chromatography and High Performance Liquid Chromatography. HPTLC revealed presence of quercetin as 44.60, 27.13 % and rutin as 32.00, 36.31 % w/w. HPLC revealed presence of quercetin as 34.00, 35.00 % and rutin as 21.99, 45.03 % w/v. Abbreviation Used: HPTLC: High Performance Thin Layer Chromatography; HPLC: High Pressure Liquid Chromatography, UV: Ultraviolet, CC: Carissa congesta, BH: Benincasa hispida PMID:26941534

Role of thin-layer chromatography in ascertaining Kashaya Rasa (astringent taste) in medicinal plants on the concept of Samana and Vichitra Pratyayarabdha principles of Ayurveda

PubMed Central

Kolhe, Rasika H.; Acharya, Rabinarayan; Shukla, Vinay J.

2014-01-01

Background: Pharmacodynamics, in Ayurveda has been described in terms of Rasadipanchaka. Rasa, on one side indicates the Bhautika composition of the drug and on the other side predicts the action. Different analytical techniques, pharmaceutical processes are being used in Ayurveda for the purpose of standardization of raw drugs. Aim: In this study an attempt has been made to apply chromatographic technique in determination of Kashaya (astringent) Rasa (taste). Materials and Methods: Two important Kashaya dominant drugs Kulattha (Dolichos biflorus Linn.) and Kanchanara (Bauhinia variegata Linn.), falling under Vichitra and Samana Pratyayarabdha category respectively, were subjected to physicochemical parameters and qualitative tests followed by High-Performance Thin-Layer Chromatography (HPTLC). In light of chromatographic fingerprinting; sample preparation protocol is modified to incorporate taste threshold in correlation. Column chromatography is used for first-level discrimination technique followed by HPTLC. Kashaya Rasa Dominant Zone (KsRDZ) was separated and subjected to TLC fingerprinting. The KsRDZ fraction was designated as Botanical Reference Material (BRM) in further analysis. Results: Ash value, Alcohol and water soluble extract value were more in B variegata as compared to D biflorus. Presence of tannin in both the samples was confirmed through qualitative test. The KsRDZ fraction separated at Rf 0.46 and 0.48 for Kulattha and Kanchanara respectively. Conclusion: The results showed that the planner chromatography technique seems very useful when BRM hypothesis was adjunct to method that explains the categorization according to traditional Rasa domain classification method. PMID:25558164

Thin-layer chromatographic determination of erythromycin and other macrolide antibiotics in livestock products.

PubMed

Petz, M; Solly, R; Lymburn, M; Clear, M H

1987-01-01

A method is described for determination of 4 macrolide antibiotics in livestock products. Erythromycin, tylosin, oleandomycin, and spiramycin were extracted from animal tissues, milk, and egg with acetonitrile at pH 8.5. Cleanup was done by adding sodium chloride and dichloromethane, evaporating the organic layer, and subsequent acid/base partitioning. After the antibiotics were separated by thin-layer chromatography (TLC), they were reacted with xanthydrol and could be detected as purple spots down to 0.02 mg/kg without interference by other commonly used therapeutic drugs (23 were tested). Anisaldehyde-sulfuric acid, cerium sulfate-molybdic acid, phosphomolybdic acid, and Dragendorff's reagent proved to be less sensitive as visualizing agents. For quantitation, TLC plates were scanned at 525 nm. Recoveries were between 71 and 96% for erythromycin and tylosin in liver, muscle, and egg at the 0.1-0.5 mg/kg level and 51% for erythromycin in milk at the 0.02 mg/kg level (coefficient of variation = 10-18%). Bioautography with Bacillus subtilis was used to confirm results, in addition to TLC analysis of derivatized antibiotics and liquid chromatography with electrochemical detection. Various derivatization procedures for erythromycin were investigated for improved ultra-violet or fluorescence detection in liquid chromatography.

Detecting and characterizing N-acyl-homoserine lactone signal molecules by thin-layer chromatography

PubMed Central

Shaw, Paul D.; Ping, Gao; Daly, Sean L.; Cha, Chung; Cronan, John E.; Rinehart, Kenneth L.; Farrand, Stephen K.

1997-01-01

Many Gram-negative bacteria regulate gene expression in response to their population size by sensing the level of acyl-homoserine lactone signal molecules which they produce and liberate to the environment. We have developed an assay for these signals that couples separation by thin-layer chromatography with detection using Agrobacterium tumefaciens harboring lacZ fused to a gene that is regulated by autoinduction. With the exception of N-butanoyl-l-homoserine lactone, the reporter detected acyl-homoserine lactones with 3-oxo-, 3-hydroxy-, and 3-unsubstituted side chains of all lengths tested. The intensity of the response was proportional to the amount of the signal molecule chromatographed. Each of the 3-oxo- and the 3-unsubstituted derivatives migrated with a unique mobility. Using the assay, we showed that some bacteria produce as many as five detectable signal molecules. Structures could be assigned tentatively on the basis of mobility and spot shape. The dominant species produced by Pseudomonas syringae pv. tabaci chromatographed with the properties of N-(3-oxohexanoyl)-l-homoserine lactone, a structure that was confirmed by mass spectrometry. An isolate of Pseudomonas fluorescens produced five detectable species, three of which had novel chromatographic properties. These were identified as the 3-hydroxy- forms of N-hexanoyl-, N-octanoyl-, and N-decanoyl-l-homoserine lactone. The assay can be used to screen cultures of bacteria for acyl-homoserine lactones, for quantifying the amounts of these molecules produced, and as an analytical and preparative aid in determining the structures of these signal molecules. PMID:9177164

Determination of losartan potassium, quinapril hydrochloride and hydrochlorothiazide in pharmaceutical preparations using derivative spectrophotometry and chromatographic-densitometric method.

PubMed

Stolarczyk, Mariusz; Maślanka, Anna; Apola, Anna; Krzek, Jan

2013-01-01

Two methods, spectrophotometric and chromatographic-densitometric ones, were developed for determination of losartan potassium, quinapril hydrochloride and hydrochlorothiazide in pharmaceutical preparations. Spectrophotometric method involved derivative spectrophotometry and zero order spectrophotometry. The measurements were carried out at lambda = 224.0 nm for quinapril, lambda = 261.0 nm for hydrochlorothiazide and lambda = 270.0 nm for losartan when the derivative spectrophotometry was applied and lambda = 317.0 nm when zero order spectrophotometry was applied for the determination of hydrochlorothiazide. In chromatographic-densitometric studies high performance thin layer chromatography (HPTLC) plates were used as stationary phase and a mixture of solvents n-butanol : acetic acid : water (15 : 5 : 1, v/v/v) as mobile phase. Under the established conditions good resolution of examined constituents was obtained. Retardation factor for quinapril hydrochloride was R(f) - 0.70, for losartan potassium R(f) - 0.85 and for hydrochlorothiazide R(f) - 0.78. The developed methods are characterized by high sensitivity and accuracy. For quantitative analysis, densitometric measurements were carried out at lambda = 218.0 nm for quinapril, lambda = 275.0 nm for hydrochlorothiazide and = 232.0 nm for losartan.

Reversed-phase thin-layer chromatography of homologs of Antimycin-A and related derivatives

USGS Publications Warehouse

Abidi, Sharon L.

1989-01-01

Using a reversed-phase high-performance liquid chromatographic (HPLC) technique, a mixture of antimycins A was separated into eight hitherto unreported subcomponents, Ala, Alb, A2a, A2b, A3a, A3b, A4a, and A4b. Although a base-line resolution of the known four major antimycins Al, A2, A3, and A4 was readily achieved with mobile phases containing acetate buffers, the separation of the new antibiotic subcomponents was highly sensitive to variation in mobile phase conditions. The type and composition of organic modifiers, the nature of buffer salts, and the concentration of added electrolytes had profound effects on capacity factors, separation factors, and peak resolution values. Of the numerous chromatographic systems examined, a mobile phase consisting of methanol-water (70:30) and 0.005 M tetrabutylammonium phosphate at pH 3.0 yielded the most satisfactory results for the separation of the subcomponents. Reversed-phase gradient HPLC separation of the dansylated or methylated antibiotic compounds produced superior chromatographic characteristics and the presence of added electrolytes was not a critical factor for achieving separation. Differences in the chromatographic outcome between homologous and structural isomers were interpretated based on a differential solvophobic interaction rationale. Preparative reversed-phase HPLC under optimal conditions enabled isolation of pure samples of the methylated antimycin subcomponents for use in structural studies.

Cleanup procedure for water, soil, animal and plant extracts for the use of electron-capture detector in the gas chromatographic analysis of organophosphorus insecticide residues.

PubMed

Kadoum, A M

1968-07-01

A simple, aqueous acetonitrile partition cleanup method for analyses of some common organophosphorus insecticide residues is described. The procedure described is for cleanup and quantitative recovery of parathion, methyl parathion, diazinon, malathion and thimet from different extracts. Those insecticides in the purified extracts of ground water, grain, soil, plant and animal tissues can be detected quantitatively by gas chromatography with an electron capture-detector at 0.01 ppm. Cleanup is satisfactory for paper and thin-layer chromatography for further identification of individual insecticides in the extracts.

Assessment of the chromatographic lipophilicity of eight cephalosporins on different stationary phases.

PubMed

Dąbrowska, Monika; Starek, Małgorzata; Komsta, Łukasz; Szafrański, Przemysław; Stasiewicz-Urban, Anna; Opoka, Włodzimierz

2017-04-01

The retention behaviors were investigated for a series of eight cephalosporins in thin-layer chromatography (TLC) using stationary phases of RP-2, RP-8, RP-18, NH 2 , DIOL, and CN chemically bonded silica gel. Additionally, various binary mobile phases (water/methanol and water/acetone) were used in different volume proportions. The retention behavior of the analyzed molecules was defined by R M0 constant. In addition, reversed phase high performance liquid chromatography (RP-HPLC) was performed in lipophilicity studies by using immobilized artificial membrane (IAM) stationary phase. Obtained chromatographic data (R M0 and logk' IAM ) were correlated with the lipophilicity, expressed as values of the log calculated (logP calc ) and experimental (logP exp(shake-flask) ) partition coefficient. Principal component analysis (PCA) was applied in order to obtain an overview of similarity or dissimilarity among the analyzed compounds. Hierarchical cluster analysis (HCA) was performed to compare the separation characteristics of the applied stationary phases. This study was undertaken to identify the best chromatographic system and chromatographic data processing method to enable the prediction of logP values. A comprehensive chromatographic investigation into the retention of the analyzed cephalosporins revealed a similar behavior on RP-18, RP-8 and CN stationary phases. The weak correlations obtained between experimental and certain computed lipophilicity indices revealed that R M0 and PC1/RM are relevant lipophilicity parameters and the RP-8, CN and RP-18 plates are appropriate stationary phases for lipophilicity investigation, whereas computational approaches still cannot fully replace experimentation. Copyright © 2017 Elsevier B.V. All rights reserved.

Analysis of biodiesel and biodiesel-petrodiesel blends by high performance thin layer chromatography combined with easy ambient sonic-spray ionization mass spectrometry.

PubMed

Eberlin, Livia S; Abdelnur, Patricia V; Passero, Alan; de Sa, Gilberto F; Daroda, Romeu J; de Souza, Vanderlea; Eberlin, Marcos N

2009-08-01

High performance thin layer chromatography (HPTLC) combined with on-spot detection and characterization via easy ambient sonic-spray ionization mass spectrometry (EASI-MS) is applied to the analysis of biodiesel (B100) and biodiesel-petrodiesel blends (BX). HPTLC provides chromatographic resolution of major components whereas EASI-MS allows on-spot characterization performed directly on the HPTLC surface at ambient conditions. Constituents (M) are detected by EASI-MS in a one component-one ion fashion as either [M + Na](+) or [M + H](+). For both B100 and BX samples, typical profiles of fatty acid methyl esters (FAME) detected as [FAME + Na](+) ions allow biodiesel typification. The spectrum of the petrodiesel spot displays a homologous series of protonated alkyl pyridines which are characteristic for petrofuels (natural markers). The spectrum for residual or admixture oil spots is characterized by sodiated triglycerides [TAG + Na](+). The application of HPTLC to analyze B100 and BX samples and its combination with EASI-MS for on-spot characterization and quality control is demonstrated.

Development and validation of a simple high performance thin layer chromatography method combined with direct 1,1-diphenyl-2-picrylhydrazyl assay to quantify free radical scavenging activity in wine.

PubMed

Agatonovic-Kustrin, Snezana; Morton, David W; Yusof, Ahmad P

2016-04-15

The aim of this study was to: (a) develop a simple, high performance thin layer chromatographic (HPTLC) method combined with direct 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay to rapidly assess and compare free radical scavenging activity or anti-oxidant activity for major classes of polyphenolics present in wines; and (b) to investigate relationship between free radical scavenging activity to the total polyphenolic content (TPC) and total antioxidant capacity (TAC) in the wine samples. The most potent free radical scavengers that we tested for in the wine samples were found to be resveratrol (polyphenolic non-flavonoid) and rutin (flavonoid), while polyphenolic acids (caffeic acid and gallic acid) although present in all wine samples were found to be less potent free radical scavengers. Therefore, the total antioxidant capacity was mostly affected by the presence of resveratrol and rutin, while total polyphenolic content was mostly influenced by the presence of the less potent free radical scavengers gallic and caffeic acids. Copyright © 2015 Elsevier Ltd. All rights reserved.

Thin Layer Chromatographic Resolution of Some β-adrenolytics and a β2-Agonist Using Bovine Serum Albumin as Chiral Additive in Stationary Phase.

PubMed

Malik, Poonam; Bhushan, Ravi

2018-01-01

Direct enantiomeric resolution of commonly used five racemic β-adrenolytics, namely, bisoprolol, atenolol, propranolol, salbutamol and carvedilol has been achieved by thin layer chromatography using bovine serum albumin (BSA) as chiral additive in stationary phase. Successful resolution of the enantiomers of all racemic β-adrenolytics was achieved by use of different composition of simple organic solvents having no buffer or inorganic ions. The effect of variation in pH, temperature, amount of BSA as the additive, and composition of mobile phase on resolution was systematically studied. Spots were visualized in iodine vapors. Native enantiomers for each of the five analytes were isolated and identified and their elution order was determined. The limit of detection was found to be 0.7, 1.2, 0.84, 1.6 and 0.9 μg (per spot) for each enantiomer of bisoprolol, atenolol, propranolol, salbutamol and carvedilol, respectively. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Purification and partial characterization of Flavotoxin A.

PubMed Central

Hu, W J; Zhang, G S; Chu, F S; Meng, H D; Meng, Z H

1984-01-01

A heat-resistant, low-molecular-weight toxin was isolated from semisolid potato dextrose agar medium after inoculation with Flavobacterium farinofermentans sp. nov., which was isolated from fermented corn meal that caused some outbreaks of food poisoning in China. The toxin was purified by solvent partition, Sephadex LH-20 gel filtration, and C-18 reversed-phase column chromatography. Thin-layer chromatography and high-pressure liquid chromatographic methods were developed for the identification and analysis of the toxin. The purified toxin exhibited a single spot in thin-layer chromatography and a single peak in high-pressure liquid chromatography and had adsorption maxima at 232 and 267 nm. Mass spectral analysis indicated a molecular weight of 169 with an experimental formula of C9H13O3. The 50% lethal dose of purified toxin in mice (oral) was less than 6.84 mg/kg, but greater than 0.68 mg/kg. Postmortem examination showed that the mice died of some type of neurological and cardiovascular system toxicity. The name Flavotoxin A is being assigned to the toxin. PMID:6391376

Pressurized planar electrochromatography, high-performance thin-layer chromatography and high-performance liquid chromatography--comparison of performance.

PubMed

Płocharz, Paweł; Klimek-Turek, Anna; Dzido, Tadeusz H

2010-07-16

Kinetic performance, measured by plate height, of High-Performance Thin-Layer Chromatography (HPTLC), High-Performance Liquid Chromatography (HPLC) and Pressurized Planar Electrochromatography (PPEC) was compared for the systems with adsorbent of the HPTLC RP18W plate from Merck as the stationary phase and the mobile phase composed of acetonitrile and buffer solution. The HPLC column was packed with the adsorbent, which was scrapped from the chromatographic plate mentioned. An additional HPLC column was also packed with adsorbent of 5 microm particle diameter, C18 type silica based (LiChrosorb RP-18 from Merck). The dependence of plate height of both HPLC and PPEC separating systems on flow velocity of the mobile phase and on migration distance of the mobile phase in TLC system was presented applying test solute (prednisolone succinate). The highest performance, amongst systems investigated, was obtained for the PPEC system. The separation efficiency of the systems investigated in the paper was additionally confirmed by the separation of test component mixture composed of six hormones. 2010 Elsevier B.V. All rights reserved.

Separation, identification and quantification of carotenoids and chlorophylls in dietary supplements containing Chlorella vulgaris and Spirulina platensis using High Performance Thin Layer Chromatography.

PubMed

Hynstova, Veronika; Sterbova, Dagmar; Klejdus, Borivoj; Hedbavny, Josef; Huska, Dalibor; Adam, Vojtech

2018-01-30

In this study, 14 commercial products (dietary supplements) containing alga Chlorella vulgaris and cyanobacteria Spirulina platensis, originated from China and Japan, were analysed. UV-vis spectrophotometric method was applied for rapid determination of chlorophylls, carotenoids and pheophytins; as degradation products of chlorophylls. High Performance Thin-Layer Chromatography (HPTLC) was used for effective separation of these compounds, and also Atomic Absorption Spectrometry for determination of heavy metals as indicator of environmental pollution. Based on the results obtained from UV-vis spectrophotometric determination of photosynthetic pigments (chlorophylls and carotenoids), it was confirmed that Chlorella vulgaris contains more of all these pigments compared to the cyanobacteria Spirulina platensis. The fastest mobility compound identified in Chlorella vulgaris and Spirulina platensis using HPTLC method was β-carotene. Spectral analysis and standard calibration curve method were used for identification and quantification of separated substances on Thin-Layer Chromatographic plate. Quantification of copper (Cu 2+ , at 324.7 nm) and zinc (Zn 2+ , at 213.9nm) was performed using Flame Atomic Absorption Spectrometry with air-acetylene flame atomization. Quantification of cadmium (Cd 2+ , at 228.8 nm), nickel (Ni 2+ , at 232.0nm) and lead (Pb 2+ , at 283.3nm) by Electrothermal Graphite Furnace Atomic Absorption Spectrometry; and quantification of mercury (Hg 2+ , at 254nm) by Cold Vapour Atomic Absorption Spectrometry. Copyright © 2017 Elsevier B.V. All rights reserved.

Resolution and isolation of enantiomers of (±)-isoxsuprine using thin silica gel layers impregnated with L-glutamic acid, comparison of separation of its diastereomers prepared with chiral derivatizing reagents having L-amino acids as chiral auxiliaries.

PubMed

Bhushan, Ravi; Nagar, Hariom

2015-03-01

Thin silica gel layers impregnated with optically pure l-glutamic acid were used for direct resolution of enantiomers of (±)-isoxsuprine in their native form. Three chiral derivatizing reagents, based on DFDNB moiety, were synthesized having l-alanine, l-valine and S-benzyl-l-cysteine as chiral auxiliaries. These were used to prepare diastereomers under microwave irradiation and conventional heating. The diastereomers were separated by reversed-phase high-performance liquid chromatography on a C18 column with detection at 340 nm using gradient elution with mobile phase containing aqueous trifluoroacetic acid and acetonitrile in different compositions and by thin-layer chromatography (TLC) on reversed phase (RP) C18 plates. Diastereomers prepared with enantiomerically pure (+)-isoxsuprine were used as standards for the determination of the elution order of diastereomers of (±)-isoxsuprine. The elution order in the experimental study of RP-TLC and RP-HPLC supported the developed optimized structures of diastereomers based on density functional theory. The limit of detection was 0.1-0.09 µg/mL in TLC while it was in the range of 22-23 pg/mL in HPLC and 11-13 ng/mL in RP-TLC for each enantiomer. The conditions of derivatization and chromatographic separation were optimized. The method was validated for accuracy, precision, limit of detection and limit of quantification. Copyright © 2014 John Wiley & Sons, Ltd.

Isolation, purification, toxicity and some physicochemical properties of mycotoxins produced by aspergillus quadrilineatus isolated from acha (Digitaria exilis stapf) in Plateau State of Nigeria.

PubMed

Gbodi, T A

1993-06-01

Some physico-chemical and toxicological studies were carried out on mycotoxins elaborated by Aspergillus quadrilineatus isolated from a grain foodstuff, acha (Digitaria exilis) in the Plateau State of Nigeria. The mycotoxins produced by A quadrilineatus were extractable from rice culture by chloroform. Column chromatographic separations of the crude extract in silica gel using different elution solvents and biological tests showed that the mycotoxins came off in the diethylether, chloroform and mostly in the ethyl acetate fractions. Use of different available mycotoxin standards on silica gel G coated chromatoplates revealed that 1 of the mycotoxins produced by A quadrilineatus was sterigmatocystin. Two other more toxic mycotoxins were isolated and purified from the crude chloroform extract; their column, preparative thin-layer chromatographic, infrared and UV-spectrophotometric characteristics were established. The infrared spectra of the 2 purified mycotoxins suggested that the carbonyl group of their structures were similar to that of aflatoxin.

Chromatographic Techniques for Rare Earth Elements Analysis

NASA Astrophysics Data System (ADS)

Chen, Beibei; He, Man; Zhang, Huashan; Jiang, Zucheng; Hu, Bin

2017-04-01

The present capability of rare earth element (REE) analysis has been achieved by the development of two instrumental techniques. The efficiency of spectroscopic methods was extraordinarily improved for the detection and determination of REE traces in various materials. On the other hand, the determination of REEs very often depends on the preconcentration and separation of REEs, and chromatographic techniques are very powerful tools for the separation of REEs. By coupling with sensitive detectors, many ambitious analytical tasks can be fulfilled. Liquid chromatography is the most widely used technique. Different combinations of stationary phases and mobile phases could be used in ion exchange chromatography, ion chromatography, ion-pair reverse-phase chromatography and some other techniques. The application of gas chromatography is limited because only volatile compounds of REEs can be separated. Thin-layer and paper chromatography are techniques that cannot be directly coupled with suitable detectors, which limit their applications. For special demands, separations can be performed by capillary electrophoresis, which has very high separation efficiency.

Rapid evaluation and comparison of natural products and antioxidant activity in calendula, feverfew, and German chamomile extracts.

PubMed

Agatonovic-Kustrin, Snezana; Babazadeh Ortakand, Davoud; Morton, David W; Yusof, Ahmad P

2015-03-13

The present study describes a simple high performance thin layer chromatographic (HPTLC) method for the simultaneous quantification of apigenin, chamazulene, bisabolol and the use of DPPH free radical as a post-chromatographic derivatization agent to compare the free radical scavenging activities of these components in leaf and flower head extracts from feverfew, German chamomile and marigold from the Asteraceae family. Feverfew (Tanacetum parthenium) leaves have been traditionally used in the treatment of migraine with parthenolide being the main bioactive compound. However, due to similar flowers, feverfew is sometimes mistaken for the German chamomile (Matricaria recutita). Bisabolol and chamazulene are the main components in chamomile essential oil. Marigold (Calendula officinalis) was included in the study for comparison, as it belongs to the same family. Parthenolide was found to be present in all leaf extracts but was not detected in calendula flower extract. Chamazulene and bisabolol were found to be present in higher concentrations in chamomile and Calendula flowers. Apigenin was detected and quantified only in chamomile extracts (highest concentration in flower head extracts). Antioxidant activity in sample extracts was compared by superimposing the chromatograms obtained after post-chromatographic derivatization with DPPH and post-chromatographic derivatization with anisaldehyde. It was found that extracts from chamomile flower heads and leaves have the most prominent antioxidant activity, with bisabolol and chamazulene being the most effective antioxidants. Crown Copyright © 2015. Published by Elsevier B.V. All rights reserved.

Quality assessment of Herba Leonuri based on the analysis of multiple components using normal- and reversed-phase chromatographic methods.

PubMed

Dong, Shuya; He, Jiao; Hou, Huiping; Shuai, Yaping; Wang, Qi; Yang, Wenling; Sun, Zheng; Li, Qing; Bi, Kaishun; Liu, Ran

2017-12-01

A novel, improved, and comprehensive method for quality evaluation and discrimination of Herba Leonuri has been developed and validated based on normal- and reversed-phase chromatographic methods. To identify Herba Leonuri, normal- and reversed-phase high-performance thin-layer chromatography fingerprints were obtained by comparing the colors and R f values of the bands, and reversed-phase high-performance liquid chromatography fingerprints were obtained by using an Agilent Poroshell 120 SB-C18 within 28 min. By similarity analysis and hierarchical clustering analysis, we show that there are similar chromatographic patterns in Herba Leonuri samples, but significant differences in counterfeits and variants. To quantify the bio-active components of Herba Leonuri, reversed-phase high-performance liquid chromatography was performed to analyze syringate, leonurine, quercetin-3-O-robiniaglycoside, hyperoside, rutin, isoquercitrin, wogonin, and genkwanin simultaneously by single standard to determine multi-components method with rutin as internal standard. Meanwhile, normal-phase high-performance liquid chromatography was performed by using an Agilent ZORBAX HILIC Plus within 6 min to determine trigonelline and stachydrine using trigonelline as internal standard. Innovatively, among these compounds, bio-active components of quercetin-3-O-robiniaglycoside and trigonelline were first determined in Herba Leonuri. In general, the method integrating multi-chromatographic analyses offered an efficient way for the standardization and identification of Herba Leonuri. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

HPTLC method for the simultaneous determination of four indole alkaloids in Rauwolfia tetraphylla: a study of organic/green solvent and continuous/pulse sonication.

PubMed

Gupta, Shikha; Shanker, Karuna; Srivastava, Santosh K

2012-07-01

A new validated high-performance thin-layer chromatographic (HPTLC) method has been developed for the simultaneous quantitation of four antipsychotic indole alkaloids (IAs), reserpiline (RP, 1), α-yohimbine (YH, 2), isoreserpiline (IRP, 3) and 10-methoxy tetrahydroalstonine (MTHA, 4) as markers in the leaves of Rauwolfia tetraphylla. Extraction efficiency of the targeted IAs from the leaf matrix with organic and ecofriendly (green) solvents using percolation, ultrasonication and microwave techniques were studied. Non-ionic surfactants, viz. Triton X-100, Triton X-114 and Genapol X-80 were used for extraction and no back-extraction or liquid chromatographic steps were used to remove the targeted IAs from the surfactant-rich extractant phase. The optimized cloud point extraction was found a potentially useful methodology for the preconcentration of the targeted IAs. The separation was achieved on silica gel 60F(254) HPTLC plates using hexane-ethylacetate-methanol (5:4:1, v/v/v) as mobile phase. The quantitation of IAs (1-4) was carried out using the densitometric reflection/absorption mode at 520 nm after post chromatographic derivatization using Dragendorff's reagent. The method was validated for peak purity, precision, accuracy, robustness, limit of detection (LOD) and quantitation (LOQ). Method specificity was confirmed using retention factor (R(f)) and visible spectral (post chromatographic scan) correlation of marker compounds in the samples and standard tracks. Copyright © 2012 Elsevier B.V. All rights reserved.

Method to fabricate silicon chromatographic column comprising fluid ports

DOEpatents

Manginell, Ronald P.; Frye-Mason, Gregory C.; Heller, Edwin J.; Adkins, Douglas R.

2004-03-02

A new method for fabricating a silicon chromatographic column comprising through-substrate fluid ports has been developed. This new method enables the fabrication of multi-layer interconnected stacks of silicon chromatographic columns.

[Application of surface-enhanced Raman spectra to the analysis of Chinese Ephedra soup medicines].

PubMed

Zhang, J; Wang, Y

1998-06-01

A new method was developed to analyse the spectra of ephedrine in Chinese ephedra soup medicines, using surface-enhanced technique to combine thin layer chromatographic (TLC) technique with surface-enhanced Raman spectroscopy (SERS). The study indicates that the main vibrant characteristic spec tral band of the ephedrine molecules can be obtained by TLC in the samples of about 8 microg, and expounds char acteristics of the sample molecules and the silica gel. Therefore, it is clarified that the main chemical composi tion of Chinese medicines can be carried as finger-print type appraisal by combining TLC and SERS.

Analysis of phytochemical profile of Terminalia arjuna bark extract with antioxidative and antimicrobial properties

PubMed Central

Mandal, Shreya; Patra, Arpita; Samanta, Animesh; Roy, Suchismita; Mandal, Arpita; Mahapatra, Tapasi Das; Pradhan, Shrabani; Das, Koushik; Nandi, Dilip Kumar

2013-01-01

Objective To investigate phytochemical screening, antimicrobial activity and qualitative thin layer chromatographic separation of flavonoid components, antioxidant activity and total flavonoid compound of Terminalia arjuna. Methods For phytochemical screening, some common and available standard tests were done. Antimicrobial bioassay was done through agar well diffusion method. Detection of antioxidant activity and flavonoid compounds were done through thin layer chromatography. Total antioxidant activity was measured by 2, 2-diphenyl-1-picrylhydrazyl (DPPH) in colorimetric method. Aluminum chloride colorimetric method was used for total flavonoid determination. Results Phytochemical screening showed the active compounds presence in high concentration, such as phytosterol, lactones, flavonoids, phenolic compounds and tannins and glycosides. The antimicrobial activity of extract showed that greater inhibition zone against Gram negative bacteria than Gram positive bacteria. This methanolic extract showed a promising antioxidant activity, as absorption of DPPH redicles decreased in DPPH free radical scavenging assay. Flavonoids components having antioxidant property present in the methanol extract at a level of 199.00 mg quercetin equivalent/g of dried methanol extract in colorimetric method. Conclusions The Terminalia arjuna bark extract revealed the presence of bio-active constituents which are known to exhibit medicinal as well as physiological activities. PMID:24093787

Simultaneous determination of atenolol and amlodipine in tablets by high-performance thin-layer chromatography.

PubMed

Argekar, A P; Powar, S G

2000-01-01

A new simple, precise, rapid and selective high-performance thin-layer chromatographic (HPTLC) method has been developed for the simultaneous determination of atenolol (ATL) and amlodipine (AMLO) in tablets, using methylene chloride:methanol:ammonia solution (25% NH3) (8.8:1.3:0.1; v/v) as the mobile phase and Merck HPTLC plates (0.2 mm thickness) precoated with 60F254 silica gel on aluminium sheet as the stationary phase. Detection was carried out densitometrically using a UV detector at 230 nm. The retention factors of ATL and AMLO were 0.33 and 0.75, respectively. Calibration curves were linear in the range 10-500 microg ml(-1) for both. Assays of ATL and AMLO were 49.87 mg per tablet (relative standard deviation (R.S.D.), 1.3%) and 4.90 mg per tablet (R.S.D., 1.38%) for brand I, and 49.27 mg per tablet (R.S.D., 1.12%) and 4.98 mg per tablet (R.S.D., 1.42%) for brand II, respectively. The percentage recoveries for ATL and AMLO for brands I and II were 99.06 and 99.30%, and 99.27 and 99.15%, respectively.

Evaluation of thin-layer chromatography methods for quality control of commercial products containing Aesculus hippocastanum, Turnera diffusa, Matricaria recutita, Passiflora incarnata, and Tilia occidentalis.

PubMed

Ramírez-Durón, Rosalba; Ceniceros-Almaguer, Lucía; Salazar-Aranda, Ricardo; Salazar-Cavazos, Ma de la Luz; Waksman de Torres, Noemi

2007-01-01

In Mexico, plant-derived products with health claims are sold as herbal dietary supplements, and there are no rules for their legal quality control. Aesculus hippocastanum, Turnera diffusa, Matricaria recutita, Passiflora incarnata, and Tilia occidentalis are some of the major commercial products obtained from plants used in this region. In this paper, we describe the effectiveness of thin-layer chromatography methods to provide for the quality control of several commercial products containing these plants. Standardized extracts were used. Of the 49 commercial products analyzed, only 32.65% matched the chromatographic characteristic of standardized extracts. A significant number of commercial products did not match their label, indicating a problem resulting from the lack of regulation for these products. The proposed methods are simple, sensitive, and specific and can be used for routine quality control of raw herbals and formulations of the tested plants. The results obtained show the need to develop simple and reliable analytical methods that can be performed in any laboratory for the purpose of quality control of dietary supplements or commercial herbal products sold in Mexico.

Validated stability-indicating densitometric thin-layer chromatography: application to stress degradation studies of minocycline.

PubMed

Jain, Nilu; Jain, Gaurav Kumar; Ahmad, Farhan Jalees; Khar, Roop Krishen

2007-09-19

A simple, stability-indicating high-performance thin-layer liquid chromatographic (HPTLC) method for analysis of minocycline was developed and validated. The densitometric analysis was carried out at 345 nm using methanol-acetonitrile-isopropyl alcohol-water (5:4:0.5:0.5, v/v/v/v) as mobile phase. The method employed TLC aluminium plates pre-coated with silica gel 60F-254 as the stationary phase. To achieve good result, plates were sprayed with a 10% (w/v) solution of disodium ethylene diaminetetraacetic acid (EDTA), the pH of which was adjusted to 9.0. Compact spots of minocycline were found at R(f) = 0.30+/-0.02. For proposed procedure, linearity (r = 0.9997), limit of detection (3.7 ng spot(-1)), recovery (99.23-100.16%), and precision (% R.S.D. < or = 0.364) was found to be satisfactory. The drug undergoes acidic and basic degradation, oxidation and photodegradation. All the peaks of degradation products were well resolved from the pure drug with significantly different R(f) values. The acidic and alkaline degradation kinetics of minocycline, evaluated using this method, is found to be of first order.

Secondary metabolites isolation in natural products chemistry: comparison of two semipreparative chromatographic techniques (high pressure liquid chromatography and high performance thin-layer chromatography).

PubMed

Do, Thi Kieu Tiên; Hadji-Minaglou, Francis; Antoniotti, Sylvain; Fernandez, Xavier

2014-01-17

Chemical investigations on secondary metabolites in natural products chemistry require efficient isolation techniques for characterization purpose as well as for the evaluation of their biological properties. In the case of phytochemical studies, the performance of the techniques is critical (resolution and yield) since the products generally present a narrow range of polarity and physicochemical properties. Several techniques are currently available, but HPLC (preparative and semipreparative) is the most widely used. To compare the performance of semipreparative HPLC and HPTLC for the isolation of secondary metabolites in different types of extracts, we have chosen carvone from spearmint essential oil (Mentha spicata L.), resveratrol from Fallopia multiflora (Thunb.) Haraldson, and rosmarinic acid from rosemary (Rosmarinus officinalis L.) extracts. The comparison was based on the chromatographic separation, the purity and quantity of isolated compounds, the solvent consumption, the duration and the cost of the isolation operations. The results showed that semipreparative HPTLC can in some case offer some advantages over conventional semipreparative HPLC. Copyright © 2013 Elsevier B.V. All rights reserved.

Effect of alpha-tocopherol, pyridoxine and dexpanthenol on the stress in crease of nonesterified fatty acids levels in the brain.

PubMed

Chmela, Z; Sklenovský, A; Dostálová, K; Rypka, M

1993-01-01

The supposed antistress effect of vitamins-alpha-tocopherol, pyridoxine and dexpanthenol (pantothenic acid precursor)--was followed on the model of nociceptive stress in laboratory rats. The decrease of the stress enhancement of nonesterified fatty acids (NEFA), estimated in the brain cortex, hypothalamus and the brain stem, was taken for the indicator of the antistress effect. Nonesterified fatty acids were determined with the help of gas chromatography following the separation performed by thin layer chromatographic method. Five-day application of alpha-tocopherol acetate (per os, 300 mg.kg-1) led to a decrease of the stress enhancement of arachidonic acid level in the brain stem.

Stress Studies of Tenofovir Disoproxil Fumarate by HPTLC in Bulk Drug and Pharmaceutical Formulation

PubMed Central

Havele, Shweta; Dhaneshwar, Sunil R.

2012-01-01

A stability-indicating high-performance thin-layer chromatographic (HPTLC) method for determination of tenofovir disoproxil fumarate in bulk drug and in tablet has been developed and validated. The mobile phase selected was chloroform : methanol (9.0 : 1.0, v/v) with ultraviolet (UV) detection at 260 nm. The retention factor was found to be 0.49 ± 0.03 with correlation coefficients of 0.9994 in the range 300–1500 ng/spot and with an accuracy of 99.25%. Method had the potential to determine tenofovir disoproxil fumarate from tablet without any interference, and it was a stability-indicating one. PMID:22606065

Isolation of an iron-binding compound from Pseudomonas aeruginosa.

PubMed Central

Cox, C D; Graham, R

1979-01-01

An iron-binding compound was isolated from ethyl acetate extracts of culture supernatant fluids of Pseudomonas aeruginosa and was purified by successive paper and thin-layer chromatographic procedures. The purified compound was characterized by UV, visible, infrared, and fluorescence spectroscopy. The compound possesses phenolic characteristics, with little or no similarity to dihydroxybenzoates and no indication of a hydroxamate group. P. aeruginosa synthesized the compound during active growth in culture media containing less than 5 X 10(-6) M added FeCl3. When added to iron-poor cultures of P. aeruginosa, the compound promoted the growth of the bacterium and also reversed growth inhibition by the iron chelator ethylenediamine-di-(o-hydroxyphenylacetic acid). PMID:104968

Development of a quantitative high-performance thin-layer chromatographic method for sucralose in sewage effluent, surface water, and drinking water.

PubMed

Morlock, Gertrud E; Schuele, Leonard; Grashorn, Sebastian

2011-05-13

Sucralose, a persistent chlorinated substance used as sweetener, can already be found in waste water, and various countries focused on the release of sucralose into the aquatic environment. A quantitative high-performance thin-layer chromatography (HPTLC) method, which is orthogonal to existing methods, was developed to analyze sucralose in water. After sample preparation, separation of up to 17 samples was performed in parallel on a HPTLC plate silica gel 60 F(254) with a mixture of isopropyl acetate, methanol and water (15:3:1, v/v/v) within 15 min. Due to the weak native UV absorption of sucralose (≤200 nm), various post-chromatographic derivatization reactions were compared to selectively detect sucralose in effluent and surface water matrices. Thereby p-aminobenzoic acid reagent was discovered as a new derivatization reagent for sucralose. Compared to the latter and to β-naphthol, derivatization with aniline diphenylamine o-phosphoric acid reagent was slightly preferred and densitometry was performed by absorbance measurement at 400 nm. The limit of quantification (LOQ) of sucralose in drinking and surface water was calculated to be 100 ng/L for a given recovery rate of 80% and the extraction of a 0.5 L water sample. The sucralose content determined in four water samples obtained during an interlaboratory trial in 2008 was in good agreement to the mean laboratory values of that trial. According to the t-test, which compares the results with the target value, the means obtained by HPTLC were not significantly different from the respective means of six laboratories, analyzed by HPLC-MS/MS or HPLC-TOF-MS with the use of mostly isotopically labeled standards. The good accuracy and high sample throughput capacity proved HPTLC as a well suited method regarding quantification of sucralose in various aqueous matrices. Copyright © 2010 Elsevier B.V. All rights reserved.

High-performance thin-layer chromatographic methods for the determination of febuxostat and febuxostat/diclofenac combination in human plasma.

PubMed

El-Yazbi, Fawzi A; Amin, Omayma A; El-Kimary, Eman I; Khamis, Essam F; Younis, Sameh E

2018-06-01

Two simple, sensitive and specific high-performance thin-layer chromatographic (HPTLC) methods were developed for the determination of febuxostat (FEB) individually, and simultaneously with diclofenac (DIC) in human plasma. Method A presents the first HPTLC-ultraviolet attempt for FEB determination in human plasma. FEB was separated from endogenous plasma components (at hR F  = 70) with ethyl acetate-methanol-water (9:2:1, v/v) mixture as mobile phase and quantified by densitometry at its λ max (315 nm). Method B is considered the first attempt for the simultaneous determination of FEB and DIC in human plasma. A mixture of petroleum ether-chloroform-ethyl acetate-formic acid (7.5:1:2.5:0.25, v/v) was used as the mobile phase. The two drugs were separated at hR F of 39 and 60 for FEB and DIC, respectively. FEB and DIC were quantified by densitometry at their isoabsorptive point (289 nm). FEB calibration plots were linear between 0.1 and 7 μg mL -1 in both methods A and B. In method B, DIC showed linear response in the range of 0.08-8 μg mL -1 . Sample preparation was performed by liquid-liquid extraction using diethyl ether. Both methods did not record any interference from plasma matrix, the studied drugs' metabolites or their decomposition products. They were successfully applied for the determination of the studied drugs in healthy male volunteers after oral administration of FEB or FEB/DIC dosage forms. FEB plasma concentration increased significantly when given with DIC. The proposed methods provided very simple, rapid and cheap approaches that might be attractive for the future pharmacokinetic and bioavailability studies of FEB and/or DIC. Copyright © 2018 Elsevier B.V. All rights reserved.

Application of a validated stability-indicating densitometric thin-layer chromatographic method to stress degradation studies on moxifloxacin.

PubMed

Motwani, Sanjay K; Khar, Roop K; Ahmad, Farhan J; Chopra, Shruti; Kohli, K; Talegaonkar, S

2007-01-16

A simple, sensitive, selective, precise and stability-indicating high-performance thin-layer chromatographic (HPTLC) method for densitometric determination of moxifloxacin both as a bulk drug and from pharmaceutical formulation was developed and validated as per the International Conference on Harmonization (ICH) guidelines. The method employed TLC aluminium plates pre-coated with silica gel 60F-254 as the stationary phase and the mobile phase consisted of n-propanol-ethanol-6M ammonia solution (4:1:2, v/v/v). Densitometric analysis of moxifloxacin was carried out in the absorbance mode at 298 nm. Compact spots for moxifloxacin were found at R(f) value of 0.58+/-0.02. The linear regression analysis data for the calibration plots showed good linear relationship with r=0.9925 in the working concentration range of 100-800 ng spot(-1). The method was validated for precision, accuracy, ruggedness, robustness, specificity, recovery, limit of detection (LOD) and limit of quantitation (LOQ). The LOD and LOQ were 3.90 and 11.83 ng spot(-1), respectively. Drug was subjected to acid and alkali hydrolysis, oxidation, dry heat, wet heat treatment and photodegradation. All the peaks of degradation products were well resolved from the standard drug with significantly different R(f) values. Statistical analysis proves that the developed HPTLC method is reproducible and selective. As the method could effectively separate the drug from its degradation products, it can be employed as stability-indicating one. Moreover, the proposed HPTLC method was utilized to investigate the kinetics of the acidic and alkaline degradation processes at different temperatures. Arrhenius plot was constructed and apparent pseudo-first-order rate constant, half-life and activation energy were calculated. In addition the pH-rate profile for degradation of moxifloxacin in constant ionic strength buffer solutions within the pH range 1.2-10.8 was studied.

Rapid identification of serotypes of Mycobacterium avium-M. intracellulare complex by using infected swine sera and reference antigenic glycolipids.

PubMed

Ikawa, H; Oka, S; Murakami, H; Hayashi, A; Yano, I

1989-11-01

The species of 136 strains of acid-fast bacteria isolated from swine with mycobacteriosis were identified by numerical taxonomy and chemotaxonomy on the basis of mycolic acid subclass composition as members of the Mycobacterium avium-M. intracellulare (MAI) complex. The isolates were further classified by using both thin-layer chromatography of the antigenic glycopeptidolipids (GPL) obtained from the bacteria by the method of Tsang et al. (A. Y. Tsang, I. Drupa, M. Goldberg, J. K. McClatchy, and P. J. Brennan, Int. J. Syst. Bacteriol. 33:285-292, 1983) and the seroagglutination test devised by W. B. Schaefer (Am. Rev. Respir. Dis. 92[Suppl.]:85-93, 1965). For the reference standard, purified antigenic GPL of serotypes 4, 8, and 9 were isolated and their structures were analyzed by negative fast-atom bombardment-mass spectrometry. The fast-atom bombardment-mass spectrometric spectra of the intact GPL antigens of serotypes 4, 8, and 9 agreed with the structures reported earlier by Brennan et al. (P. J. Brennan and M. B. Goren, J. Biol. Chem. 254:4205-4211, 1979; P. J. Brennan, G. O. Aspinall, and J. E. Nam Shin, J. Biol. Chem. 256:6817-6822, 1981). With these antigenic GPL, the thin-layer chromatographic behaviors of the alkali-stable lipids of the above-described isolates were examined. These MAI complex isolates fell into the serotype 8 (85 strains), 4 (33 strains), and 9 (7 strains) and untypeable (11 strains) categories. Furthermore, an enzyme-linked immunosorbent assay (ELISA) based on type-specific glycolipid antigens and infected swine sera was used to diagnose the serological types of the MAI complex isolates. Of 14 cases typed by both the seroagglutination reaction and thin-layer chromatography, 13 showed clear agreement with the ELISA results. The results demonstrated that ELISA using infected sera was especially useful, and it can be recommended on the basis of simplicity, sensitivity, and specificity as an adjunct to the seroaggulutination test and thin-layer chromatography for identification of mycobacteria belonging to the MAI complex.

IMMUNO-MODULATORY PROPERTIES OF PREBIOTICS EXTRACTED FROM vernonia amygdalina.

PubMed

Im, Ezeonu; Ae, Asuquo; Bn, Ukwah; Po, Ukoha

2016-01-01

Vernonia amygdalina , commonly called bitter-leaf, is widely consumed in many parts of Africa, and Nigeria, in particular. The leaf extract has been reported to have antimicrobial, anti-plasmodial, anti-helminthic, as well as prebiotic properties, but its immuno-modulatory effects have not been well-studied, neither have the prebiotics been identified. This study evaluated the immuno-modulatory properties of the aqueous leaf extract and identified the prebiotic components. The immuno-modulatory potential was evaluated by monitoring the effects of oral administration of the extract on immunological, haematological and lipid profiles of Rattus norvegicus , while the prebiotic components were identified by thin layer chromatography (TLC), following liquid-liquid fractionation of the extract. Consumption of the extract caused significant increases in CD4+-, white blood cell-, total lymphocyte- and high density lipid (HDL) counts; decreases in low density lipid (LDL) and triglycerides and no significant effect on haemoglobin (Hb) and packed cell volume (PCV) in the blood of test animals. The water-soluble fraction of the extract contained most of the phyto-constituents of the extract and Thin Layer Chromatographic analysis of the fraction revealed the presence of fructo-oligosaccharide and galacto-oligosaccharide prebiotics. The results from this study have shown that the aqueous leaf extract of V. amygdalina has positive immune-modulatory and haematologic effects and contains some important prebiotic compounds.

Analysis of phytochemical profile of Terminalia arjuna bark extract with antioxidative and antimicrobial properties.

PubMed

Mandal, Shreya; Patra, Arpita; Samanta, Animesh; Roy, Suchismita; Mandal, Arpita; Mahapatra, Tapasi Das; Pradhan, Shrabani; Das, Koushik; Nandi, Dilip Kumar

2013-12-01

To investigate phytochemical screening, antimicrobial activity and qualitative thin layer chromatographic separation of flavonoid components, antioxidant activity and total flavonoid compound of Terminalia arjuna. For phytochemical screening, some common and available standard tests were done. Antimicrobial bioassay was done through agar well diffusion method. Detection of antioxidant activity and flavonoid compounds were done through thin layer chromatography. Total antioxidant activity was measured by 2, 2-diphenyl-1-picrylhydrazyl (DPPH) in colorimetric method. Aluminum chloride colorimetric method was used for total flavonoid determination. Phytochemical screening showed the active compounds presence in high concentration, such as phytosterol, lactones, flavonoids, phenolic compounds and tannins and glycosides. The antimicrobial activity of extract showed that greater inhibition zone against Gram negative bacteria than Gram positive bacteria. This methanolic extract showed a promising antioxidant activity, as absorption of DPPH redicles decreased in DPPH free radical scavenging assay. Flavonoids components having antioxidant property present in the methanol extract at a level of 199.00 mg quercetin equivalent/g of dried methanol extract in colorimetric method. The Terminalia arjuna bark extract revealed the presence of bio-active constituents which are known to exhibit medicinal as well as physiological activities. Copyright © 2013 Asian Pacific Tropical Biomedical Magazine. Published by Elsevier B.V. All rights reserved.

Incidence of seed-borne fungi and aflatoxins in Sudanese lentil seeds.

PubMed

el-Nagerabi, S A; Elshafie, A E

2001-01-01

Thirteen seed samples of lentil (Lens esculenta) were incubated on agar plate and moist filter papers (Moist Chambers) at 28 +/- 2 degrees C for determination of the incidence of seed-borne fungi. Aflatoxins content of the seeds was measured using the bright greenish- yellow fluorescence test (BGYF) and thin-layer chromatography (TLC). Sixty-nine species and seven varieties, which belong to 24 genera of fungi, were isolated from this crop. Of these fungi, 51 species and two varieties are considered new for this crop, whereas seven genera and 13 species are new to the mycoflora of the Sudan. The genus Aspergillus (13 species and 6 varieties) which comprising 44% of the total colony count was the most prevalent genus followed by Rhizopus (2 species, 19%), Penicillium (6 species) and Fusarium (8 species) (12%), Chaetomium (3 species) and Cladosporium (5 species) (6%), where the 18 genera (1-4 species) showed very low level of incidence (19%). Of the possible pathogens of lentil plants, F. oxysporum the main cause of vascular wilt was recovered from seeds of this crop. Thin layer chromatographic analysis of chloroform extracts of 13 seed samples showed that only one samples was naturally contaminated with aflatoxins B1, B2, G1 and G2 (14.3 micrograms/kg).

Electrospun polyvinyl alcohol ultra-thin layer chromatography of amino acids.

PubMed

Lu, Tian; Olesik, Susan V

2013-01-01

Electrospun polyvinyl alcohol (PVA) ultrathin layer chromatographic (UTLC) plates were fabricated using in situ crosslinking electrospinning technique. The value of these ULTC plates were characterized using the separation of fluorescein isothiocyanate (FITC) labeled amino acids and the separation of amino acids followed visualization using ninhydrin. The in situ crosslinked electrospun PVA plates showed enhanced stability in water and were stable when used for the UTLC study. The selectivity of FITC labeled amino acids on PVA plate was compared with that on commercial Si-Gel plate. The efficiency of the separation varied with analyte concentration, size of capillary analyte applicator, analyte volume, and mat thickness. The concentration of 7mM or less, 50μm i.d. capillary applicator, minimum volume of analyte solution and three-layered mat provides the best efficiency of FITC-labeled amino acids on PVA UTLC plate. The efficiency on PVA plate was greatly improved compared to the efficiency on Si-Gel HPTLC plate. The hydrolysis products of aspartame in diet coke, aspartic acid and phenylalanine, were also successfully analyzed using PVA-UTLC plate. Copyright © 2012 Elsevier B.V. All rights reserved.

CHROMATOGRAPHIC TECHNIQUES IN PHARMACEUTICAL ANALYSIS IN POIAND: HISTORY AND THE PRESENCE ON THE BASIS OF PAPERS PUBLISHED IN SELECTED POLISH PHARMACEUTICAL JOURNALS IN XX CENTURY.

PubMed

Bilek, Maciej; Namieśnik, Jacek

2016-01-01

For a long time, chromatographic techniques and techniques related to them have stimulated the development of new procedures in the field of pharmaceutical analysis. The newly developed methods, characterized by improved metrological parameters, allow for more accurate testing of, among others, the composition of raw materials, intermediates and final products. The chromatographic techniques also enable studies on waste generated in research laboratories and factories producing pharmaceuticals and parapharmaceuticals. Based on the review of reports published in Polish pharmaceutical journals, we assessed the impact of chromatographic techniques on the development of pharmaceutical analysis. The first chromatographic technique used in pharmaceutical analysis was a so-called capillary analysis. It was applied in the 1930s to control the identity of pharmaceutical formulations. In the 1940s and 1950s, the chromatographic techniques were mostly a subject of review publications, while their use in experimental work was rare. Paper chromatography and thin layer chromatography were introduced in the 1960s and 1970s, respectively. These new analytical tools have contributed to the intensive development of research in the field of phytochemistry and the analysis of herbal medicines. The development of colunm chromatography-based techniques, i.e., gas chromatography and high performance liquid chromatography took place in the end of 20th century. Both aforementioned techniques were widely applied in pharmaceutical analysis, for example, to assess the stability of drugs, test for impurities and degradation products as well as in pharmacokinetics studies. The first decade of 21" century was the time of new detection methods in gas and liquid chromatography. The information sources used to write this article were Polish pharmaceutical journals, both professional and scientific, originating from the interwar and post-war period, i.e., "Kronika Farmaceutyczna", "Farmacja Współczesna", "Wiadomości Farmaceutyczne", "Acta Poloniae Pharmaceutica", "Farmacja Polska", "Dissertationes Pharmaceuticae", "Annales UMCS sectio DDD Phamacia". The number of published works using various chromatography techniques was assessed based on the content description of individual issues of the journal "Acta Poloniae Pharmaceutica".

Preparation and characterization of 5-(4-hydroxy-3-nitrobenzyl)-3-phenyl-2-thiohydantoin, the phenylthiohydantoin derivative of 3-nitrotyrosine.

PubMed

Lilova, A; Kleinschmidt, T; Nedkov, P; Braunitzer, G

1986-10-01

The phenylthiocarbamoyl derivative of 3-nitrotyrosine was synthesized according to the known Edman method and then converted to its phenylthiohydantoin derivative [5-(4-hydroxy-3-nitrobenzyl)-3-phenyl-2-thiohydantion] by incubation in 0.5M HCl for 24 h at room temperature. After drying over P2O5 the chromatographically pure substance could be obtained by double recrystallization from hot acetic acid. It could be established that a shorter incubation time leads to an incomplete conversion and higher temperatures cause polymerization of the product. The compounds could be characterized by thin-layer and high-performance liquid chromatography, melting point, elemental analysis as well as NMR- and absorption spectroscopy.

Simultaneous densitometric determination of anthelmintic drug albendazole and its metabolite albendazole sulfoxide by HPTLC in human plasma and pharmaceutical formulations.

PubMed

Pandya, Jui J; Sanyal, Mallika; Shrivastav, Pranav S

2017-09-01

A new, simple, accurate and precise high-performance thin-layer chromatographic method has been developed and validated for simultaneous determination of an anthelmintic drug, albendazole, and its active metabolite albendazole, sulfoxide. Planar chromatographic separation was performed on aluminum-backed layer of silica gel 60G F 254 using a mixture of toluene-acetonitrile-glacial acetic acid (7.0:2.9:0.1, v/v/v) as the mobile phase. For quantitation, the separated spots were scanned densitometrically at 225 nm. The retention factors (R f ) obtained under the established conditions were 0.76 ± 0.01 and 0.50 ± 0.01 and the regression plots were linear (r 2  ≥ 0.9997) in the concentration ranges 50-350 and 100-700 ng/band for albendazole and albendazole sulfoxide, respectively. The method was validated for linearity, specificity, accuracy (recovery) and precision, repeatability, stability and robustness. The limit of detection and limit of quantitation found were 9.84 and 29.81 ng/band for albendazole and 21.60 and 65.45 ng/band for albendazole sulfoxide, respectively. For plasma samples, solid-phase extraction of analytes yielded mean extraction recoveries of 87.59 and 87.13% for albendazole and albendazole sulfoxide, respectively. The method was successfully applied for the analysis of albendazole in pharmaceutical formulations with accuracy ≥99.32%. Copyright © 2017 John Wiley & Sons, Ltd.

Quantitation of polymethoxylated flavones in orange juice by high-performance liquid chromatography.

PubMed

Rouseff, R L; Ting, S V

1979-08-01

A quantitative high-performance liquid chromatographic (HPLC) procedure for the determination of the five major polymethoxylated flavones (PMFs) in orange juice has been developed. It employs a unique ternary solvent system with coupled UV-fluorescence detection. The dual detectors were employed to determine the presence of interfering substances and served as a cross check on quantitation. Stop flow UV and fluorescence scanning was used to identify peaks and determine the presence of impurities. Although all five citrus PMFs fluoresce, some HPLC fluorescence peaks were too small to be of much practical use. All five citrus PMFs could be quantitated satisfactorily with the fixed wavelength UV (313 nm) detector. The HPLC procedure has been used to evaluate each step in the preparation. The optimum extracting solvent was selected and one time consuming step was eliminated, as it was found to be unnecessary. HPLC values for nobiletin and sinensetin are in good agreement with the thin-layer chromatographic (TLC) values in the literature. HPLC values for the other three flavones were considerably lower than those reported in the literature. The HPLC procedure is considerably faster than the TLC procedure with equal or superior precision and accuracy.

Engineering and validation of a novel lipid thin film for biomembrane modeling in lipophilicity determination of drugs and xenobiotics

PubMed Central

Idowu, Sunday Olakunle; Adeyemo, Morenikeji Ambali; Ogbonna, Udochi Ihechiluru

2009-01-01

Background Determination of lipophilicity as a tool for predicting pharmacokinetic molecular behavior is limited by the predictive power of available experimental models of the biomembrane. There is current interest, therefore, in models that accurately simulate the biomembrane structure and function. A novel bio-device; a lipid thin film, was engineered as an alternative approach to the previous use of hydrocarbon thin films in biomembrane modeling. Results Retention behavior of four structurally diverse model compounds; 4-amino-3,5-dinitrobenzoic acid (ADBA), naproxen (NPX), nabumetone (NBT) and halofantrine (HF), representing 4 broad classes of varying molecular polarities and aqueous solubility behavior, was investigated on the lipid film, liquid paraffin, and octadecylsilane layers. Computational, thermodynamic and image analysis confirms the peculiar amphiphilic configuration of the lipid film. Effect of solute-type, layer-type and variables interactions on retention behavior was delineated by 2-way analysis of variance (ANOVA) and quantitative structure property relationships (QSPR). Validation of the lipid film was implemented by statistical correlation of a unique chromatographic metric with Log P (octanol/water) and several calculated molecular descriptors of bulk and solubility properties. Conclusion The lipid film signifies a biomimetic artificial biological interface capable of both hydrophobic and specific electrostatic interactions. It captures the hydrophilic-lipophilic balance (HLB) in the determination of lipophilicity of molecules unlike the pure hydrocarbon film of the prior art. The potentials and performance of the bio-device gives the promise of its utility as a predictive analytic tool for early-stage drug discovery science. PMID:19735551

Molecular separations using nanostructured porous thin films fabricated by glancing angle deposition

NASA Astrophysics Data System (ADS)

Bezuidenhout, Louis Wentzel

Biomolecular separation techniques are an enabling technology that indirectly in.uence many aspects of our lives. Advances have led to faster analyses, reduced costs, higher specificity, and new analytical techniques, impacting areas such as health care, environmental monitoring, polymer sciences, agriculture, and nutrition. Further development of separations technology is anticipated to follow the path of computing technology such that miniaturization through the development of microfluidics technology, lab-on-a-chip systems, and other integrative, multi-component systems will further extend our analysis capabilities. Creation of new and improvement of existing separation technologies is an integral part of the pathway to miniaturized systems. the work of this thesis investigates molecular separations using porous nanostructured films fabricated by the thin film process glancing angle deposition (GLAD). Structural architecture, pore size and shape, and film density can be finely controlled to produce high-surface area thin films with engineered morphology. The characteristic size scales and structural control of GLAD films are well-suited to biomolecules and separation techniques, motivating investigation into the utility and performance of GLAD films for biomolecular separations. This project consisted of three phases. First, chromatographic separation of dye molecules on silica GLAD films was demonstrated by thin layer chromatography Direct control of film nanostructure altered the separation characteristics; most strikingly, anisotropic structures provided two-dimensional analyte migration. Second, nanostructures made with GLAD were integrated in PDMS microfluidic channels using a sacrificial etching process; DNA molecules (10/48 kbp and 6/10/20 kbp mixtures) were electrophoretically separated on a microfluidic chip using a porous bed of SiO2 vertical posts. Third, mass spectrometry of proteins and drugs in the mass range of 100-1300 m/z was performed using laser desorption/ionization (LDI) on silicon GLAD films, and the influence of film thickness, porosity, structure, and substrate on performance was characterized. The application of GLAD nanostructured thin films to biomolecular separations is demonstrated and validated in this thesis. Chromatographic separation of dye molecules, electrophoretic separation of DNA molecules, and mass spectrometric isolation of small proteins and drug molecules by laser desorption ionization were demonstrated using GLAD films. All three methods yielded promising results and establish GLAD as a potential technology for biomolecular separations.

Detection Progress of Selected Drugs in TLC

PubMed Central

Pyka, Alina

2014-01-01

This entry describes applications of known indicators and dyes as new visualizing reagents and various visualizing systems as well as photocatalytic reactions and bioautography method for the detection of bioactive compounds including drugs and compounds isolated from herbal extracts. Broadening index, detection index, characteristics of densitometric band, modified contrast index, limit of detection, densitometric visualizing index, and linearity range of detected compounds were used for the evaluation of visualizing effects of applied visualizing reagents. It was shown that visualizing effect depends on the chemical structure of the visualizing reagent, the structure of the substance detected, and the chromatographic adsorbent applied. The usefulness of densitometry to direct detection of some drugs was also shown. Quoted papers indicate the detection progress of selected drugs investigated by thin-layer chromatography (TLC). PMID:24551853

Effects of Infection by Mycosphaerella graminicola on Translocation of Fluquinconazole in Wheat Seedlings.

PubMed

Metcalfe, R J; Shaw, M W; Russell, P E

2000-12-01

ABSTRACT Translocation of (14)C-labeled fluquinconazole was measured using combustion analysis and radio thin-layer-chromatographic analysis in seedling wheat leaves uninfected and infected with Mycosphaerella graminicola. Two isolates were used with differing sensitivity to demethylation inhibitor fungicides. Fluquinconazole was translocated acropetally, but not basipetally. Fluquinconazole accumulated around infection sites within 6 days after treatment. Accumulation occurred before M. graminicola hyphae had colonized the host mesophyll further than one host cell around the invasion site. This suggested that the accumulation was caused by a host response to infection. Infrared gas analysis showed that rates of transpiration and stomatal conductance in inoculated leaves were significantly increased very soon after inoculation but net photosynthesis was decreased. The actual mechanism of fungicide accumulation was not determined.

Fast assessment of planar chromatographic layers quality using pulse thermovision method.

PubMed

Suszyński, Zbigniew; Świta, Robert; Loś, Joanna; Zarzycka, Magdalena B; Kaleniecka, Aleksandra; Zarzycki, Paweł K

2014-12-19

The main goal of this paper is to demonstrate capability of pulse thermovision (thermal-wave) methodology for sensitive detection of photothermal non-uniformities within light scattering and semi-transparent planar stationary phases. Successful visualization of stationary phases defects required signal processing protocols based on wavelet filtration, correlation analysis and k-means 3D segmentation. Such post-processing data handling approach allows extremely sensitive detection of thickness and structural changes within commercially available planar chromatographic layers. Particularly, a number of TLC and HPTLC stationary phases including silica, cellulose, aluminum oxide, polyamide and octadecylsilane coated with adsorbent layer ranging from 100 to 250μm were investigated. Presented detection protocol can be used as an efficient tool for fast screening the overall heterogeneity of any layered materials. Moreover, described procedure is very fast (few seconds including acquisition and data processing) and may be applied for fabrication processes online controlling. In spite of planar chromatographic plates this protocol can be used for assessment of different planar separation tools like paper based analytical devices or micro total analysis systems, consisted of organic and non-organic layers. Copyright © 2014 Elsevier B.V. All rights reserved.

[Separation and purification of an endogenous inhibitor of sodium pump from chansu by thin-layer chromatography and reversed-phase high performance liquid chromatography].

PubMed

Li, S Q

2001-11-01

An endogenous inhibitor of the sodium pump from the Chinese medication Chansu was purified. The dry substance Chansu was extracted with methanol. The dry residue dissolved in water and filtered subsequently through membrane filters with the exclusion size of 1000 Da, 3000 Da and 10000 Da in a Filtron Pro Vario-3-System and applied to thin-layer chromatographic plate made of Silica gel 60 F254 + 366 developed with a mixture of CHCl3-MeOH-H2O(75:20:5, volume ratio). The fractions with Rf 0.55 inhibiting the sodium pump were purified on an HPLC C18-RP column using a linear H2O-methanol gradient with 220 nm and 300 nm DAD detection. The bioactivity was measured by 86Rb-uptake into human red blood cells. The results showed that a low molecular weight, water soluble compound, which inhibited the sodium pump activity in the red blood cells and had a maximum absorbance at 250 nm was isolated from the Chinese medication Chansu. Several mg of the compound in pure state could be obtained from 1 kg Chansu. It was different from ouabain and proscillaridin A in chemical structure, because ouabain and proscillaridin A show a UV maximum absorption at 220 nm and 300 nm, while the new inhibitor at 250 nm.

Quantitative Determination of L-DOPA in Seeds of Mucuna Pruriens Germplasm by High Performance Thin Layer Chromatography

PubMed Central

Raina, Archana P.; Khatri, Renu

2011-01-01

Mucuna pruriens Linn. is an important medicinal plant used for treatment of Parkinson's disease and many others in ancient Indian medical system. L-DOPA extracted from seeds of Mucuna is a constituent of more than 200 indigenous drug formulations and is more effective as drug than the synthetic counterpart. A densitometric high performance thin-layer chromatographic (HPTLC) method was developed for quantification of L-DOPA content present in the seeds extract. The method involves separation of L-DOPA on precoated silica gel 60 GF254 HPTLC plates using a solvent system of n-butanol-acetic-acid-water (4:1:1, v/v) as the mobile phase. Quantification was done at 280 nm using absorbance reflectance mode. Linearity was found in the concentration range of 100 to 1000 ng/spot with the correlation coefficient value of 0.9980. The method was validated for accuracy, precision and repeatability. Mean recovery was 100.89%. The LOD and LOQ for L-DOPA determination were found to be 3.41 ng/spot and 10.35 ng/spot respectively. The proposed HPTLC method was found to be precise, specific and accurate for quantitative determination of L-DOPA. It can be used for rapid screening of large germplasm collections of Mucuna pruriens for L-DOPA content. The method was used to study variation in fifteen accessions of Mucuna germplasm collected from different geographical regions. PMID:22707835

Quantitative Determination of L-DOPA in Seeds of Mucuna Pruriens Germplasm by High Performance Thin Layer Chromatography.

PubMed

Raina, Archana P; Khatri, Renu

2011-07-01

Mucuna pruriens Linn. is an important medicinal plant used for treatment of Parkinson's disease and many others in ancient Indian medical system. L-DOPA extracted from seeds of Mucuna is a constituent of more than 200 indigenous drug formulations and is more effective as drug than the synthetic counterpart. A densitometric high performance thin-layer chromatographic (HPTLC) method was developed for quantification of L-DOPA content present in the seeds extract. The method involves separation of L-DOPA on precoated silica gel 60 GF(254) HPTLC plates using a solvent system of n-butanol-acetic-acid-water (4:1:1, v/v) as the mobile phase. Quantification was done at 280 nm using absorbance reflectance mode. Linearity was found in the concentration range of 100 to 1000 ng/spot with the correlation coefficient value of 0.9980. The method was validated for accuracy, precision and repeatability. Mean recovery was 100.89%. The LOD and LOQ for L-DOPA determination were found to be 3.41 ng/spot and 10.35 ng/spot respectively. The proposed HPTLC method was found to be precise, specific and accurate for quantitative determination of L-DOPA. It can be used for rapid screening of large germplasm collections of Mucuna pruriens for L-DOPA content. The method was used to study variation in fifteen accessions of Mucuna germplasm collected from different geographical regions.

Layer-by-layer self-assembled graphene oxide/silica microsphere composites as stationary phase for high performance liquid chromatography.

PubMed

Liang, Xiaojing; Liu, Shujuan; Song, Xinwang; Zhu, Yangwen; Jiang, Shengxiang

2012-11-21

Graphene oxide (GO) has been layer-by-layer assembled onto silica microspheres to form a GO/SiO(2) composite stationary phase. All the characterizations of GO/SiO(2) by elemental analysis, Raman spectroscopy and Fourier transformed infrared spectrometry confirmed that with the increase of the assembled layer, GO gradually increases on the silica surface. The chromatographic properties of bare SiO(2) and GO/SiO(2) with different GO assembled layers show that the amount of GO plays an important role in the separation of analytes. Only the appropriate amount of GO on SiO(2) can perform a good chromatographic separation. The comparison between chromatographic performances of bare SiO(2) column, GO/SiO(2)-2 column and C18 commercial column clearly show that GO/SiO(2)-2 and C18 columns obtained a better separation; GO/SiO(2)-2 exhibits a large π-electron system and C18 exhibits hydrophobicity. The eluting order, peak width and resolution of analyte on GO/SiO(2)-2 column was highly dependent on the size of its π-electron system, while on the C18 column the decisive factor is its hydrophobic property.

From functional food to medicinal product: Systematic approach in analysis of polyphenolics from propolis and wine

PubMed Central

Medić-Šarić, Marica; Rastija, Vesna; Bojić, Mirza; Maleš, Željan

2009-01-01

In the last decade we have been working on standardization of propolis extract and determination of active constituents of wine those are rich in polyphenolics and have nutritional as well as therapeutic value. Here we are summarizing our results and providing overview on systematic approach how to analyse natural products rich in flavonoids and phenolic acids. Chromatographic methods (thin layer chromatography and high performance liquid chromatography) were used for identification, quantification, and characterization of individual flavonoid or phenolic acid. Total content of active constituents and antioxidant activity were determined by spectrophotometry. Pharmacokinetic parameters were determined by high performance liquid chromatography and using appropriate software. Quantitative structure-activity relationship study of antioxidant activity was conducted, as well as assessment of prolonged propolis supplementation on antioxidative status of organism. Thin layer chromatography-densitometry has been proven as quick and reliable method for standard analysis of propolis and wine; the best mobile phase being chloroform – methanol – formic acid (98–100%) in ratio 44 : 3.5 : 2.5 (v/v). Higher number of polyphenolics was determined by high performance liquid chromatography; 15 compared to 9 by thin layer chromatography. Interactions in situ with acetylsalicylic acid were detected with most of polyphenolics analysed. Plasma protein binding and blood-barrier penetration was greatest for flavone. The interactions with human serum albumin have been grater than 95% for all flavonoids analysed. The prolonged propolis consumption increased superoxide dismutase activity. The necessity of standardization of natural products and their registration as functional nutraceuticals demand easy, quick and inexpensive methods of analysis. In this work we provided overview of analytical part for polyphenolics that could be used as data for possible registration of final products either as functional food or medicinal product. This feature introduces the readers to the authors' research through a concise overview of the selected topic. Reference to important work from others in the field is included. PMID:19624827

Chromatographic and Spectrophotometric Analysis of Phenolic Compounds from Fruits of Libidibia ferrea Martius

PubMed Central

Ferreira, Magda R. A.; Fernandes, Mônica T. M.; da Silva, Wliana A. V.; Bezerra, Isabelle C. F.; de Souza, Tatiane P.; Pimentel, Maria F.; Soares, Luiz A. L.

2016-01-01

Background: Libidibia ferrea (Mart. ex Tul.) L.P. Queiroz (Fabaceae) is a tree which is native to Brazil, widely known as “Jucá,” where its herbal derivatives are used in folk medicine with several therapeutic properties. The constituents, which have already been described in the fruit, are mainly hydrolysable tannins (gallic acid [GA] and ellagic acid [EA]). Objective: The aim of this study was to investigate the phenolic variability in the fruit of L. ferrea by ultraviolet/visible (UV/VIS) and chromatographic methods (high-performance liquid chromatography [HPLC]/high-performance thin layer chromatography [HPTLC]). Materials and Methods: Several samples were collected from different regions of Brazil and the qualitative (fingerprints by HPTLC and HPLC) and quantitative analysis (UV/VIS and HPLC) of polyphenols were performed. Results: The HPTLC and HPLC profiles allowed separation and identification of both major analytical markers: EA and GA. The chemical profiles were similar in a number of spots or peaks for the samples, but some differences could be observed in the intensity or area of the analytical markers for HPTLC or HPLC, respectively. Regarding the quantitative analysis, the polyphenolic content by UV/VIS ranged from 13.99 to 37.86 g% expressed as GA or from 10.75 to 29.09 g% expressed as EA. The contents of EA and GA by liquid chromatography-reversed phase (LC-RP) method ranged from 0.57 to 2.68 g% and from 0.54 to 3.23 g%, respectively. Conclusion: The chemical profiles obtained by HPTLC or HPLC, as well as the quantitative analysis by spectrophotometry or LC-RP method, were suitable for discrimination of each herbal sample and can be used as tools for the comparative analysis of the fruits from L. ferrea. SUMMARY The polyphenols of fruits of Libidibia ferrea can be quantified by UV/VIS and HPLCThe HPLC method was able to detect the gallic and ellagic acids in several samples of fruits of Libidibia ferreaThe phenolic profiles of fruits from Libidibia ferrea by HPTLC and HPLC were reproductible. Abbreviations used: HPTLC: high performance thin layer chromatography, HPLC: high performance liquid chromatography, UV-Vis: spectrophotometry PMID:27279721

Temperature Regulation of Growth and Endogenous Abscisic Acid-like Content of Tulipa gesneriana L

PubMed Central

Aung, Louis H.; De Hertogh, August A.

1979-01-01

The ontogenetic changes of dry matter and abscisic acid (ABA)-like content in the component organs of Tulipa gesneriana L. `Paul Richter' and `Golden Melody' under two temperature storage regimes were determined. The organ dry matter and ABA showed marked differences during 13 and 5 C dry storage and during subsequent growth at 13 C. Scale dry matter of both cultivars declined sharply when grown at 13 C. The basalplate of the cultivars showed an initial gain in dry matter, but declined subsequently. The shoot of both cultivars stored at 13 C exhibited greater dry matter gain than at 5 C. In contrast, the bulblets of the cultivars at 5 C showed a much higher rate of dry matter accumulation than at 13 C. An inhibitory substance extracted from tulip bulb organs co-chromatographed with authentic ABA and had identical thin layer chromatographic RF values of ABA in five solvent systems. The total ABA content per bulb increased 3-fold in `Golden Melody' and 2- to 4-fold in `Paul Richter' during the course of the temperature treatments. ABA was low in the scales and shoot, but it was high in the basalplate, bulblets, and roots. It is suggested that the probable ABA biosynthetic sites of tulip bulb are the developing bulblets, basalplate, and roots. PMID:16660867

HPTLC Method for the Determination of Paracetamol, Pseudoephedrine and Loratidine in Tablets and Human Plasma

PubMed Central

Farid, Nehal Fayek; Abdelaleem, Eglal A.

2016-01-01

A sensitive, accurate and selective high performance thin layer chromatography (HPTLC) method was developed and validated for the simultaneous determination of paracetamol (PAR), its toxic impurity 4-aminophenol (4-AP), pseudoephedrine HCl (PSH) and loratidine (LOR). The proposed chromatographic method has been developed using HPTLC aluminum plates precoated with silica gel 60 F254 using acetone–hexane–ammonia (4:5:0.1, by volume) as a developing system followed by densitometric measurement at 254 nm for PAR, 4-AP and LOR, while PSH was scanned at 208 nm. System suitability testing parameters were calculated to ascertain the quality performance of the developed chromatographic method. The method was validated with respect to USP guidelines regarding accuracy, precision and specificity. The method was successfully applied for the determination of PAR, PSH and LOR in ATSHI® tablets. The three drugs were also determined in plasma by applying the proposed method in the ranges of 0.5–6 µg/band, 1.6–12 µg/band and 0.4–2 µg/band for PAR, PSH and LOR, respectively. The results obtained by the proposed method were compared with those obtained by a reported HPLC method, and there was no significance difference between both methods regarding accuracy and precision. PMID:26762956

High-performance thin-layer chromatography and three-dimensional image analysis for the determination of rutin in pharmaceutical preparations.

PubMed

Soponar, Florin; Moţ, Augustin C; Sârbu, Costel

2010-01-01

A novel HPTLC method was developed for fast and simple quantitative determination of rutin in pharmaceutical preparations. The proposed method combines the advantages of HPTLC with the comfort and the convenience of digital processing of images. For the separation of rutin, silica gel with attached amino groups was used as the stationary phase and ethyl acetate-formic acid-methanol-water (10 + 0.9 + 1.1 + 1.7, v/v/v/v) as the mobile phase. The chromatographic plate was sprayed with 2-aminoethyldiphenyl borate solution for visual detection of the spots. For the construction of a three-dimensional chromatogram, Melanie 7.0 software was used together with an HP flatbed scanner that allowed capture of the images on chromatographic plates. The calibration curve was linear within the range of 0.95-4.78 microg/spot with an r value of 0.9984. The RSD for six replicates at three concentration levels was less than 3%, while the recovery was between 97.28 and 103.27%. The proposed method was found to be simple, precise, sensitive, and accurate and has been applied for the determination of rutin in two commercial drugs. The results were compared with the results of other techniques that generate bidimensional chromatograms and validated by UV-Vis spectrophotometry.

Simultaneous identification of synthetic and natural dyes in different food samples by UPLC-MS

NASA Astrophysics Data System (ADS)

Mandal, Badal Kumar; Mathiyalagan, Siva; Dalavai, Ramesh; Ling, Yong-Chien

2017-11-01

Fast foods and variety food items are populating among the food lovers. To improve the appearance of the food product in surviving gigantic competitive environment synthetic or natural food dyes are added to food items and beverages. Although regulatory bodies permit addition of natural colorants due to its safe and nontoxic nature in food, synthetic dyes are stringently controlled in all food products due to their toxicity by regulatory bodies. Artificial colors are need certification from the regulatory bodies for human consumption. To analyze food dyes in different food samples many analytical techniques are available like high pressure liquid chromatography (HPLC), thin layer chromatography (TLC), spectroscopic and gas chromatographic methods. However all these reported methods analyzed only synthetic dyes or natural dyes. Not a single method has analyzed both synthetic and natural dyes in a single run. In this study a robust ultra-performance liquid chromatographic method for simultaneous identification of 6 synthetic dyes (Tartrazine, Indigo carmine, Briliant blue, Fast green, malachite green, sunset yellow) and one natural dye (Na-Cu-Chlorophyllin) was developed using acquitic UPLC system equipped with Mass detector and acquity UPLC HSS T3 column (1.8 μm, 2.1 × 50 mm, 100Å). All the dyes were separated and their masses were determined through fragments’ masses analyses.

Application of micro-TLC to the total antioxidant potential (TAP) measurement.

PubMed

Głód, Bronisław K; Wantusiak, Paweł M; Piszcz, Paweł; Lewczuk, Elwira; Zarzycki, Paweł K

2015-04-15

DPPH is commonly applied for estimation of antioxidant capacity of single and complex biological samples, and changes colour from purple to yellow during reduction to DPPH-H. Importantly, for some samples, for example coloured foods, such reaction cannot be used because of interference from pigments. Therefore, the number of reported quantitative protocols involving off- or on-line sample reaction with DPPH are based on chromatographic separation of target components. In typical planar chromatographic assay, developed plates are sprayed with DPPH solution for antioxidant screening. Such approach enables simple visualisation of separated spots exhibiting antioxidant activities, but unfortunately, such procedure may also give the misleading signal for coloured spots. In the present communication we examined a new approach for measuring antioxidant capacity using quantitative analysis of DPPH and DPPH-H molecules after reaction with the sample, and then separated from the interfering compounds by micro-thin-layer chromatography. Particularly, the antioxidant capacities of coloured food samples (such as herbs and meads) were determined and the results compared with those obtained using the classical photometric assay. The main advantages of the new micro-TLC assay are (i) low cost, (ii) multiple measurements, (iii) short analysis time, (iv) simplification of sample preparation and (v) effective separation of DPPH signal from interfering compounds. Copyright © 2014 Elsevier Ltd. All rights reserved.

HPTLC Determination of Artemisinin and Its Derivatives in Bulk and Pharmaceutical Dosage

NASA Astrophysics Data System (ADS)

Agarwal, Suraj P.; Ahuja, Shipra

A simple, selective, accurate, and precise high-performance thin-layer chromatographic (HPTLC) method has been established and validated for the analysis of artemisinin and its derivatives (artesunate, artemether, and arteether) in the bulk drugs and formulations. The artemisinin, artesunate, artemether, and arteether were separated on aluminum-backed silica gel 60 F254 plates with toluene:ethyl acetate (10:1), toluene: ethyl acetate: acetic acid (2:8:0.2), toluene:butanol (10:1), and toluene:dichloro methane (0.5:10) mobile phase, respectively. The linear detector response for concentrations between 100 and 600 ng/spot showed good linear relationship with r value 0.9967, 0.9989, 0.9981 and 0.9989 for artemisinin, artesunate, artemether, and arteether, respectively. Statistical analysis proves that the method is precise, accurate, and reproducible and hence can be employed for the routine analysis.

Effect of physiological harvest stages on the composition of bioactive compounds in Cavendish bananas.

PubMed

Bruno Bonnet, Christelle; Hubert, Olivier; Mbeguie-A-Mbeguie, Didier; Pallet, Dominique; Hiol, Abel; Reynes, Max; Poucheret, Patrick

2013-04-01

The combined influence of maturation, ripening, and climate on the profile of bioactive compounds was studied in banana (Musa acuminata, AAA, Cavendish, cv. Grande Naine). Their bioactive compounds were determined by the Folin-Ciocalteu assay and high-performance thin layer chromatographic (HPTLC) method. The polyphenol content of bananas harvested after 400 degree days remained unchanged during ripening, while bananas harvested after 600 and 900 degree days exhibited a significant polyphenol increase. Although dopamine was the polyphenol with the highest concentration in banana peels during the green developmental stage and ripening, its kinetics differed from the total polyphenol profile. Our results showed that this matrix of choice (maturation, ripening, and climate) may allow selection of the banana (M. acuminata, AAA, Cavendish, cv. Grande Naine) status that will produce optimal concentrations of identified compounds with human health relevance.

Radioimmunoassay of hair for determining opiate-abuse histories

DOE Office of Scientific and Technical Information (OSTI.GOV)

Baumgartner, A.M.; Jones, P.F.; Baumgartner, W.A.

1979-07-01

Heroin and morphine metabolites can be detected in hair with the use of commerically available radioimmunoassay reagents and with minor sample preparation. Hair samples obtained from morphine-treated mice and heroin users contained nanogram levels of the drug per milligram of hair (single human hair). The results of the hair analyses for all subjects admitting the use of heroin were positive, whereas the results of only 30% of thin-layer chromatographic urinanalyses of these same subjects were positive. In addition, differences in drug concentration for sections of hair near the scalp and near the distal end correlated with the length of timemore » the drug had been used. These results exemplify the potential advantages of the use of hair analysis over urine and serum analyses in terms of accessibility, sample stability, and long-term retention of information.« less

High-performance thin-layer chromatographic-densitometric determination of secoisolariciresinol diglucoside in flaxseed.

PubMed

Coran, Silvia A; Giannellini, Valerio; Bambagiotti-Alberti, Massimo

2004-08-06

A HPTLC-densitometric method, based on an external standard approach, was developed in order to obtain a novel procedure for routine analysis of secoisolariciresinol diglucoside (SDG) in flaxseed with a minimum of sample pre-treatment. Optimization of TLC conditions for the densitometric scanning was reached by eluting HPTLC silica gel plates in a horizontal developing chamber. Quantitation of SDG was performed in single beam reflectance mode by using a computer-controlled densitometric scanner and applying a five-point calibration in the 1.00-10.00 microg/spot range. As no sample preparation was required, the proposed HPTLC-densitometric procedure demonstrated to be reliable, yet using an external standard approach. The proposed method is precise, reproducible and accurate and can be employed profitably in place of HPLC for the determination of SDG in complex matrices.

Possible Quorum Sensing in Marine Snow Bacteria: Production of Acylated Homoserine Lactones by Roseobacter Strains Isolated from Marine Snow

PubMed Central

Gram, Lone; Grossart, Hans-Peter; Schlingloff, Andrea; Kiørboe, Thomas

2002-01-01

We report here, for the first time, that bacteria associated with marine snow produce communication signals involved in quorum sensing in gram-negative bacteria. Four of 43 marine microorganisms isolated from marine snow were found to produce acylated homoserine lactones (AHLs) in well diffusion and thin-layer chromatographic assays based on the Agrobacterium tumefaciens reporter system. Three of the AHL-producing strains were identified by 16S ribosomal DNA gene sequence analysis as Roseobacter spp., and this is the first report of AHL production by these α-Proteobacteria. It is likely that AHLs in Roseobacter species and other marine snow bacteria govern phenotypic traits (biofilm formation, exoenzyme production, and antibiotic production) which are required mainly when the population reaches high densities, e.g., in the marine snow community. PMID:12147515

System for analysis of explosives

DOEpatents

Haas, Jeffrey S [San Ramon, CA

2010-06-29

A system for analysis of explosives. Samples are spotted on a thin layer chromatography plate. Multi-component explosives standards are spotted on the thin layer chromatography plate. The thin layer chromatography plate is dipped in a solvent mixture and chromatography is allowed to proceed. The thin layer chromatography plate is dipped in reagent 1. The thin layer chromatography plate is heated. The thin layer chromatography plate is dipped in reagent 2.

Mixed C18 and C1 modification on an optical fiber for chromatographic sensing.

PubMed

Zhou, Leiji; Wang, Kemin; Zuo, Xinbing; Choi, Martin M F; Chen, Yunqing; Huang, Shasheng

2003-09-01

An optical fiber-chromatographic sensor, aiming at simultaneous and selective response to multiple components following a chromatographic separation, is described. We report an improved approach for immobilization of octadecyl (C(18)) and methyl (C(1)) moieties as stationary phase on an optical fiber suitable as a sensing phase for organic solutes. By this approach, the stability and lifetime of the sensing layer as well as the detectability and retention behavior of the chromatographic sensor could be improved. Infrared spectroscopy was employed to confirm the presence of C(18) and C(1) moieties on the modified surface of the optical fiber. The chromatographic sensor was applied, with good sensitivity and chemical selectivity, to the simultaneous separation and detection of bromobenzene and toluene, using water as the mobile phase.

Phytochemical characterization, antimicrobial activity and reducing potential of seed oil, latex, machine oil and presscake of Jatropha curcas

PubMed Central

Sharma, Amit Kumar; Gangwar, Mayank; Kumar, Dharmendra; Nath, Gopal; Kumar Sinha, Akhoury Sudhir; Tripathi, Yamini Bhushan

2016-01-01

Objective: This study aims to evaluate the antimicrobial activity, phytochemical studies and thin layer chromatography analysis of machine oil, hexane extract of seed oil and methanol extract of presscake & latex of Jatropha curcas Linn (family Euphorbiaceae). Materials and Methods: J. curcas extracts were subjected to preliminary qualitative phytochemical screening to detect the major phytochemicals followed by its reducing power and content of phenol and flavonoids in different fractions. Thin layer chromatography was also performed using different solvent systems for the analysis of a number of constituents in the plant extracts. Antimicrobial activity was evaluated by the disc diffusion method, while the minimum inhibitory concentration, minimum bactericidal concentration and minimum fungicidal concentration were calculated by micro dilution method. Results: The methanolic fraction of latex and cake exhibited marked antifungal and antibacterial activities against Gram-positive and Gram-negative bacteria. Phytochemical analysis revealed the presence of alkaloids, saponins, tannins, terpenoids, steroids, glycosides, phenols and flavonoids. Reducing power showed dose dependent increase in concentration compared to standard Quercetin. Furthermore, this study recommended the isolation and separation of bioactive compounds responsible for the antibacterial activity which would be done by using different chromatographic methods such as high-performance liquid chromatography (HPLC), GC-MS etc. Conclusion: The results of the above study suggest that all parts of the plants possess potent antibacterial activity. Hence, it is important to isolate the active principles for further testing of antimicrobial and other biological efficacy. PMID:27516977

Phytochemical characterization, antimicrobial activity and reducing potential of seed oil, latex, machine oil and presscake of Jatropha curcas.

PubMed

Sharma, Amit Kumar; Gangwar, Mayank; Kumar, Dharmendra; Nath, Gopal; Kumar Sinha, Akhoury Sudhir; Tripathi, Yamini Bhushan

2016-01-01

This study aims to evaluate the antimicrobial activity, phytochemical studies and thin layer chromatography analysis of machine oil, hexane extract of seed oil and methanol extract of presscake & latex of Jatropha curcas Linn (family Euphorbiaceae). J. curcas extracts were subjected to preliminary qualitative phytochemical screening to detect the major phytochemicals followed by its reducing power and content of phenol and flavonoids in different fractions. Thin layer chromatography was also performed using different solvent systems for the analysis of a number of constituents in the plant extracts. Antimicrobial activity was evaluated by the disc diffusion method, while the minimum inhibitory concentration, minimum bactericidal concentration and minimum fungicidal concentration were calculated by micro dilution method. The methanolic fraction of latex and cake exhibited marked antifungal and antibacterial activities against Gram-positive and Gram-negative bacteria. Phytochemical analysis revealed the presence of alkaloids, saponins, tannins, terpenoids, steroids, glycosides, phenols and flavonoids. Reducing power showed dose dependent increase in concentration compared to standard Quercetin. Furthermore, this study recommended the isolation and separation of bioactive compounds responsible for the antibacterial activity which would be done by using different chromatographic methods such as high-performance liquid chromatography (HPLC), GC-MS etc. The results of the above study suggest that all parts of the plants possess potent antibacterial activity. Hence, it is important to isolate the active principles for further testing of antimicrobial and other biological efficacy.

A new high-performance thin layer chromatography-based assay of detergents and surfactants commonly used in membrane protein studies.

PubMed

Barret, Laurie-Anne; Polidori, Ange; Bonneté, Françoise; Bernard-Savary, Pierre; Jungas, Colette

2013-03-15

The hydrophobic nature of membrane proteins (MPs) necessitates the use of detergents for their extraction, solubilization and purification. Because the concentration of amphiphiles is crucial in the crystallization process, detergent quantification is essential to routine analysis. Here we describe a quantitative high-performance thin-layer chromatography (HPTLC) method we developed for the detection of small quantities of detergent bound to solubilized MPs. After optimization of aqueous deposit conditions, we show that most detergents widely used in membrane protein crystallography display distinctive mobilities in a mixture of dichloromethane, methanol and acetic acid 32:7.6:0.4 (v/v/v). Migration and derivatization conditions were optimized with n-dodecyl-β-D-maltoside (DDM), the most popular detergent for membrane protein crystallization. A linear calibration curve very well fits our data from 0.1 to 1.6 μg of DDM in water with a limit of detection of 0.05 μg. This limit of detection is the best achieved to date for a routine detergent assay, being not modified by the addition of NaCl, commonly used in protein buffers. With these chromatographic conditions, no prior treatment is required to assess the quantities of detergent bound to purified MPs, thus enabling the quantification of close structure detergents via a single procedure. This HPTLC method, which is fast and requires low sample volume, is fully suitable for routine measurements. Copyright © 2013 Elsevier B.V. All rights reserved.

Analysis of low active-pharmaceutical-ingredient signal drugs based on thin layer chromatography and surface-enhanced Raman spectroscopy.

PubMed

Li, Xiao; Chen, Hui; Zhu, Qingxia; Liu, Yan; Lu, Feng

2016-11-30

Active pharmaceutical ingredients (API) embedded in the excipients of the formula can usually be unravelled by normal Raman spectroscopy (NRS). However, more and more drugs with low API content and/or low Raman scattering coefficient were insensitive to NRS analysis, which was for the first time defined as Low API-Signal Drugs (LASIDs) in this paper. The NRS spectra of these LASIDs were similar to their dominant excipients' profiles, such as lactose, starch, microcrystalline cellulose (MCC), etc., and were classified into three types as such. 21 out of 100 kinds of drugs were screened as LASIDs and characterized further by Raman microscopic mapping. Accordingly, we proposed a tailored solution to the qualitation and quantitation problem of these LASIDs, using surface-enhanced Raman spectroscopic (SERS) detection on the thin layer chromatographic (TLC) plate both in situ and after-separation. Experimental conditions and parameters including TLC support matrix, SERS substrate, detection mode, similarity threshold, internal standard, etc., were optimized. All LASIDs were satisfactorily identified and the quantitation results agreed well with those of high performance liquid chromatography (HPLC). For some structural analogues of LASIDs, although they presented highly similar SERS spectra and were tough to distinguish even with Raman microscopic mapping, they could be successfully discriminated from each other by coupling SERS (with portable Raman spectrometer) with TLC. These results demonstrated that the proposed solution could be employed to detect the LASIDs with high accuracy and cost-effectiveness. Copyright © 2016 Elsevier B.V. All rights reserved.

Uniaxially aligned electrospun cellulose acetate nanofibers for thin layer chromatographic screening of hydroquinone and retinoic acid adulterated in cosmetics.

PubMed

Tidjarat, Siripran; Winotapun, Weerapath; Opanasopit, Praneet; Ngawhirunpat, Tanasait; Rojanarata, Theerasak

2014-11-07

Uniaxially aligned cellulose acetate (CA) nanofibers were successfully fabricated by electrospinning and applied to use as stationary phase for thin layer chromatography. The control of alignment was achieved by using a drum collector rotating at a high speed of 6000 rpm. Spin time of 6h was used to produce the fiber thickness of about 10 μm which was adequate for good separation. Without any chemical modification after the electrospinning process, CA nanofibers could be readily devised for screening hydroquinone (HQ) and retinoic acid (RA) adulterated in cosmetics using the mobile phase consisting of 65:35:2.5 methanol/water/acetic acid. It was found that the separation run on the aligned nanofibers over a distance of 5 cm took less than 15 min which was two to three times faster than that on the non-aligned ones. On the aligned nanofibers, the masses of HQ and RA which could be visualized were 10 and 25 ng, respectively, which were two times lower than those on the non-aligned CA fibers and five times lower than those on conventional silica plates due to the appearance of darker and sharper of spots on the aligned nanofibers. Furthermore, the proposed method efficiently resolved HQ from RA and ingredients commonly found in cosmetic creams. Due to the satisfactory analytical performance, facile and inexpensive production process, uniaxially aligned electrospun CA nanofibers are promising alternative media for planar chromatography. Copyright © 2014 Elsevier B.V. All rights reserved.

Combined computational-experimental approach to predict blood-brain barrier (BBB) permeation based on "green" salting-out thin layer chromatography supported by simple molecular descriptors.

PubMed

Ciura, Krzesimir; Belka, Mariusz; Kawczak, Piotr; Bączek, Tomasz; Markuszewski, Michał J; Nowakowska, Joanna

2017-09-05

The objective of this paper is to build QSRR/QSAR model for predicting the blood-brain barrier (BBB) permeability. The obtained models are based on salting-out thin layer chromatography (SOTLC) constants and calculated molecular descriptors. Among chromatographic methods SOTLC was chosen, since the mobile phases are free of organic solvent. As consequences, there are less toxic, and have lower environmental impact compared to classical reserved phases liquid chromatography (RPLC). During the study three stationary phase silica gel, cellulose plates and neutral aluminum oxide were examined. The model set of solutes presents a wide range of log BB values, containing compounds which cross the BBB readily and molecules poorly distributed to the brain including drugs acting on the nervous system as well as peripheral acting drugs. Additionally, the comparison of three regression models: multiple linear regression (MLR), partial least-squares (PLS) and orthogonal partial least squares (OPLS) were performed. The designed QSRR/QSAR models could be useful to predict BBB of systematically synthesized newly compounds in the drug development pipeline and are attractive alternatives of time-consuming and demanding directed methods for log BB measurement. The study also shown that among several regression techniques, significant differences can be obtained in models performance, measured by R 2 and Q 2 , hence it is strongly suggested to evaluate all available options as MLR, PLS and OPLS. Copyright © 2017 Elsevier B.V. All rights reserved.

Novel Chromatographic Methods for Simultaneous Quantification of Fish and Wheat Germ Oils Mixture in Pharmaceutical Dosage Forms.

PubMed

El-Yazbi, Amira F; El-Hawiet, Amr

2017-05-01

Two simple, direct and environment-friendly chromatographic methods, high-performance liquid chromatography (HPLC) and high-performance thin layer chromatographic (HPTLC), were developed for the determination of a binary mixture of fish oil (FO) and wheat germ oil (WGO), for the first time, in their pharmaceutical dosage forms with no need for any sample pretreatment. The HPLC separation was carried out using C-18 stationary phase with mobile phase of 15% formic acid (pH 6), methanol and acetonitrile through gradient-elution, 1.5 mL min-1 flow-rate and detection at 215 nm for FO and 280 nm for WGO. HPTLC separation was carried out on silica-coated plates using diethyl ether-petroleum ether (0.5:9.5, v/v) as mobile phase. Detection was at 215 nm for FO and 240 nm for WGO. Regression analysis showed good linear relationship with r > 0.999 in the concentration-ranges of 0.2-2 mg mL-1 and 2.5-20 μg band-1 for WGO by HPLC and HPTLC methods, respectively, and 0.4-10 mg mL-1 and 25-200 μg band-1 for FO by HPLC and HPTLC methods, respectively. The methods were validated, showed good analytical performance and were successfully applied for the analysis of pharmaceutical formulations and synthetic mixtures of the analytes with good recoveries. Therefore, the two methods could be conveniently adopted for routine analysis of similar products in quality control laboratories of pharmaceutical industries especially that simultaneous determination of FO-WGO mixture has not been reported previously. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Discovered acetylcholinesterase inhibition and antibacterial activity of polyacetylenes in tansy root extract via effect-directed chromatographic fingerprints.

PubMed

Móricz, Ágnes M; Ott, Péter G; Morlock, Gertrud E

2018-03-30

The knowledge about the activity of polyacetylenes was extended by their new acetylcholinesterase inhibition and antibacterial activity against plant pathogenic bacteria. For this discovery, an utmost streamlined workflow, which we consider to be of high potential in the field of natural product or superfood search was developed. It demonstrates the combined power of biological, biochemical and chemical fingerprints. Bioactive components of tansy (Tanacetum vulgare L.) root extract were profiled and identified by high-performance thin-layer chromatography hyphenated with in situ effect-directed analysis, chemical derivatizations and high-resolution mass spectrometry (HPTLC-UV/Vis/FLD-EDA-HRMS). The effect-directed profiling was performed using four bacterial bioassays including two plant pathogens, an antioxidant assay and acetyl- and butyrylcholinesterase inhibitory assays. The chromatographic, spectral and powerful mass spectrometric study of zones that exerted substantial antibacterial and/or antioxidant and/or acetylcholinesterase inhibitory effects allowed these multi-potent zones to be identified as polyacetylenes. Five polyacetylene compounds were assigned to be 2-non-1-ene-3,5,7-triynyl-3-vinyl-oxirane, 2-(2,4-hexadiynylidene)-3,4-epoxy-1,6-dioxaspiro[4.5]decane, trans- and cis-2-(2,4-hexadiynylidene)-1,6-dioxaspiro[4.5]dec-3-ene and tetradeca-2,4,6-triine-8-en-12-one. This study clearly showed the advantage of the combined use of different ionization sources, i.e. electrospray ionization via an elution-head based interface and also the Direct Analysis in Real Time interface, for HRMS analysis of compounds from the same class with very similar chromatographic behavior and polarity. Copyright © 2018 Elsevier B.V. All rights reserved.

21 CFR 862.2270 - Thin-layer chromatography system for clinical use.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Thin-layer chromatography system for clinical use... Instruments § 862.2270 Thin-layer chromatography system for clinical use. (a) Identification. A thin-layer... a mixture. The mixture of compounds is absorbed onto a stationary phase or thin layer of inert...

Method of transferring a thin crystalline semiconductor layer

DOEpatents

Nastasi, Michael A [Sante Fe, NM; Shao, Lin [Los Alamos, NM; Theodore, N David [Mesa, AZ

2006-12-26

A method for transferring a thin semiconductor layer from one substrate to another substrate involves depositing a thin epitaxial monocrystalline semiconductor layer on a substrate having surface contaminants. An interface that includes the contaminants is formed in between the deposited layer and the substrate. Hydrogen atoms are introduced into the structure and allowed to diffuse to the interface. Afterward, the thin semiconductor layer is bonded to a second substrate and the thin layer is separated away at the interface, which results in transferring the thin epitaxial semiconductor layer from one substrate to the other substrate.

Triboelectric generator

DOEpatents

Wang, Zhong L; Fan, Fengru; Lin, Long; Zhu, Guang; Pan, Caofeng; Zhou, Yusheng

2015-11-03

A generator includes a thin first contact charging layer and a thin second contact charging layer. The thin first contact charging layer includes a first material that has a first rating on a triboelectric series. The thin first contact charging layer has a first side with a first conductive electrode applied thereto and an opposite second side. The thin second contact charging layer includes a second material that has a second rating on a triboelectric series that is more negative than the first rating. The thin first contact charging layer has a first side with a first conductive electrode applied thereto and an opposite second side. The thin second contact charging layer is disposed adjacent to the first contact charging layer so that the second side of the second contact charging layer is in contact with the second side of the first contact charging layer.

Understanding the molecular signatures in leaves and flowers by desorption electrospray ionization mass spectrometry (DESI MS) imaging.

PubMed

Hemalatha, R G; Pradeep, T

2013-08-07

The difference in size, shape, and chemical cues of leaves and flowers display the underlying genetic makeup and their interactions with the environment. The need to understand the molecular signatures of these fragile plant surfaces is illustrated with a model plant, Madagascar periwinkle (Catharanthus roseus (L.) G. Don). Flat, thin layer chromatographic imprints of leaves/petals were imaged using desorption electrospray ionization mass spectrometry (DESI MS), and the results were compared with electrospray ionization mass spectrometry (ESI MS) of their extracts. Tandem mass spectrometry with DESI and ESI, in conjunction with database records, confirmed the molecular species. This protocol has been extended to other plants. Implications of this study in identifying varietal differences, toxic metabolite production, changes in metabolites during growth, pest/pathogen attack, and natural stresses are shown with illustrations. The possibility to image subtle features like eye color of petals, leaf vacuole, leaf margin, and veins is demonstrated.

Rapid, Bioassay-Guided Process for the Detection and Identification of Antibacterial Neem Oil Compounds.

PubMed

Krüzselyi, Dániel; Nagy, Róbert; Ott, Péter G; Móricz, Ágnes M

2016-08-01

Bioassay guidance was used along the whole process including method development, isolation and identification of antibacterial neem (Azadirachta indica) oil compounds. The biomonitoring was performed by direct bioautography (DB), a combination of thin-layer chromatography (TLC) and antimicrobial detection. DB of neem oil showed one antibacterial zone that was not UV-active; therefore, the TLC separation was improved under DB control. The chromatographic zone that exhibited activity against Bacillus subtilis, Xanthomonas euvesicatoria, Aliivibrio fischeri, Staphylococcus aureus and methicillin-resistant Staphylococcus aureus was characterized by TLC reagents, indicating a lipophilic, fatty acid-like chemical feature. Two compounds were found and identified in the active zone by high-performance liquid chromatography-electrospray ionization mass spectrometry as linoleic and oleic acids. Both fatty acids inhibited B. subtilis, but A. fischeri was sensitive only against linoleic acid. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Effect of physiological harvest stages on the composition of bioactive compounds in Cavendish bananas*

PubMed Central

Bruno Bonnet, Christelle; Hubert, Olivier; Mbeguie-A-Mbeguie, Didier; Pallet, Dominique; Hiol, Abel; Reynes, Max; Poucheret, Patrick

2013-01-01

The combined influence of maturation, ripening, and climate on the profile of bioactive compounds was studied in banana (Musa acuminata, AAA, Cavendish, cv. Grande Naine). Their bioactive compounds were determined by the Folin-Ciocalteu assay and high-performance thin layer chromatographic (HPTLC) method. The polyphenol content of bananas harvested after 400 degree days remained unchanged during ripening, while bananas harvested after 600 and 900 degree days exhibited a significant polyphenol increase. Although dopamine was the polyphenol with the highest concentration in banana peels during the green developmental stage and ripening, its kinetics differed from the total polyphenol profile. Our results showed that this matrix of choice (maturation, ripening, and climate) may allow selection of the banana (M. acuminata, AAA, Cavendish, cv. Grande Naine) status that will produce optimal concentrations of identified compounds with human health relevance. PMID:23549844

In vivo metabolism of clebopride in three animal species and in man.

PubMed

Segura, J; Bakke, O M; Huizing, G; Beckett, A H

1980-01-01

Clebopride is extensively metabolized in the rat, rabbit, dog, and man. By use of chromatographic methods, up to 25 metabolites in hydrolyzed and nonhydrolyzed urine have been detected. All four species produced the same main metabolites, as indicated by thin-layer chromatography. These, isolated from urine of the three animal species, were identified as N-(4'-piperidyl)-2-methoxy-4-amino-5-chlorobenzamide, N-(4'-piperidyl-2'-one)-2-methoxy-4-amino-5-chlorobenzamide, and N-(1'-alpha-hydroxybenzyl-4'-piperidyl)-2-methoxy-4-amino-5-chlorobenzamide (tentative structure of a carbinolamine more stable than expected). In the dog, 2-methoxy-4-amino-5-chlorobenzoic acid was also detected. N4-glucuronidation of clebopride and some of its metabolites has been shown to occur in the three animal species. The rabbit produced large amounts of these conjugates. Clebopride N4-sulfonate was not present in the urine of any of the species investigated.

Ethanolic extraction, purification, and partial characterization of a fluorescent toxin from the coral reef crab, Lophozozymus pictor.

PubMed

Lau, C O; Tan, C H; Khoo, H E; Li, Q T; Yuen, R

1995-01-01

A purification procedure for Lophozozymus pictor toxin (LPTX) following ethanolic extraction of whole crab homogenate is described. The ethanol-extracted toxin (LPTX-E) had higher yield and specific activity than the hot aqueous-extracted one (LPTX-H). It was found that LPTX-E was fluorescent and cochromatographed with LPTX-H on two-dimensional thin-layer chromatography. Although LPTX-E, LPTX-H, and palytoxin (P. caribaeorum, PTX) had similar migration and retention times when analysed on high performance capillary electrophoresis and gel permeation-high performance liquid chromatography respectively, LPTX-E and LPTX-H were both fluorescent in contrast to PTX. In addition, LPTX-E had a different retention time compared with PTX when chromatographed on reversed phase high performance liquid chromatography in the solvent system 80% acetonitrile and 0.02 M Tris-HCl, pH 7.2, at a 4:1 ratio, respectively, indicating some differences in their chemical structures.

Asparate Transcarbamylase Activity in Etiolated Cowpea Hypocotyls Treated with 2,4-Dichlorophenoxyacetic Acid 1

PubMed Central

Johnson, Lowell B.; Niblett, C. L.; Shively, O. D.

1973-01-01

Treating etiolated cowpea (Vigna unguiculata) seedlings with 2,4-dichlorophenoxyacetic acid resulted in 2.5-, 3.9-, and 6.5-fold increases in DNA, soluble protein, and RNA, respectively, over untreated controls 84 hours after treatment. Aspartate transcarbamylase activity increased within 12 hours after treatment, and by 84 hours it was almost 12-fold greater than that in the untreated controls. During that time, activity in untreated controls dropped 60%. The assay used 14C-aspartate, which was then separated from the 14C-ureidosuccinate product by Dowex 50 (H+ form) column chromatography. Thin layer chromatography of the reaction product indicated that most of the carbamyl-phosphate-dependent radioactivity co-chromatographed with ureidosuccinate. The reaction has a pH optimum near 10.0 and is inhibited by uridine 5′-phosphate and succinate. The data suggest that aspartate transcarbamylase is important in pyrimidine biosynthesis in 2,4-dichlorophenoxyacetic acid-treated seedlings. PMID:16658322

High-temperature adsorption layers based on fluoridated polyimide and diatomite carrier

NASA Astrophysics Data System (ADS)

Yakovleva, E. Yu.; Shundrina, I. K.; Gerasimov, E. Yu.

2017-09-01

A way of preparing separation layers by the pyrolysis of fluorinated polyimide obtained from 2,4,6-trimethyl- m-phenylenediamine (2,4,6-TM mPDA) and 2,2-bis(3',4'-dicarboxyphenyl)hexafluoropropane (6FDA) applied onto a diatomite carrier is described. Thermogravimetry, elemental analysis, low-temperature nitrogen adsorption, high-resolution electron microscopy, and gas chromatography are used to study changes in the texture and chromatographic characteristics of these layers. It is found that changes in the structure and the effectivity of separation characteristic of the layers depend on the temperature of pyrolysis, which ranges from 250 to 1100°C. It is established that a layer of separation is formed at 250-350°C, and the order of elution of hydrocarbons is similar to their chromatographic behavior on such stationary phases as OV-101. Layers of amorphous carbon formed on the surfaces of individual particles on a diatomite surface at 500-700°C. These layers ensure highly stable and selective separation of permanent gases and hydrocarbons when they are present together.

HPTLC Method for the Determination of Paracetamol, Pseudoephedrine and Loratidine in Tablets and Human Plasma.

PubMed

Farid, Nehal Fayek; Abdelaleem, Eglal A

2016-04-01

A sensitive, accurate and selective high performance thin layer chromatography (HPTLC) method was developed and validated for the simultaneous determination of paracetamol (PAR), its toxic impurity 4-aminophenol (4-AP), pseudoephedrine HCl (PSH) and loratidine (LOR). The proposed chromatographic method has been developed using HPTLC aluminum plates precoated with silica gel 60 F254 using acetone-hexane-ammonia (4:5:0.1, by volume) as a developing system followed by densitometric measurement at 254 nm for PAR, 4-AP and LOR, while PSH was scanned at 208 nm. System suitability testing parameters were calculated to ascertain the quality performance of the developed chromatographic method. The method was validated with respect to USP guidelines regarding accuracy, precision and specificity. The method was successfully applied for the determination of PAR, PSH and LOR in ATSHI(®) tablets. The three drugs were also determined in plasma by applying the proposed method in the ranges of 0.5-6 µg/band, 1.6-12 µg/band and 0.4-2 µg/band for PAR, PSH and LOR, respectively. The results obtained by the proposed method were compared with those obtained by a reported HPLC method, and there was no significance difference between both methods regarding accuracy and precision. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Degradation Kinetics Study of Alogliptin Benzoate in Alkaline Medium by Validated Stability-Indicating HPTLC Method.

PubMed

Bodiwala, Kunjan Bharatkumar; Shah, Shailesh; Thakor, Jeenal; Marolia, Bhavin; Prajapati, Pintu

2016-11-01

A rapid, sensitive, and stability-indicating high-performance thin-layer chromatographic method was developed and validated to study degradation kinetics of Alogliptin benzoate (ALG) in an alkaline medium. ALG was degraded under acidic, alkaline, oxidative, and thermal stress conditions. The degraded samples were chromatographed on silica gel 60F254-TLC plates, developed using a quaternary-solvent system (chloroform-methanol-ethyl acetate-triethyl amine, 9+1+1+0.5, v/v/v/v), and scanned at 278 nm. The developed method was validated per International Conference on Harmonization guidelines using validation parameters such as specificity, linearity and range, precision, accuracy, LOD, and LOQ. The linearity range for ALG was 100-500 ng/band (correlation coefficient = 0.9997) with an average recovery of 99.47%. The LOD and LOQ for ALG were 9.8 and 32.7 ng/band, respectively. The developed method was successfully applied for the quantitative estimation of ALG in its synthetic mixture with common excipients. Degradation kinetics of ALG in an alkaline medium was studied by degrading it under three different temperatures and three different concentrations of alkali. Degradation of ALG in the alkaline medium was found to follow first-order kinetics. Contour plots have been generated to predict degradation rate constant, half-life, and shelf life of ALG in various combinations of temperature and concentration of alkali using Design Expert software.

Radiosynthesis and Biodistribution of 99mTc-Metronidazole as an Escherichia coli Infection Imaging Radiopharmaceutical.

PubMed

Iqbal, Anam; Naqvi, Syed Ali Raza; Rasheed, Rashid; Mansha, Asim; Ahmad, Matloob; Zahoor, Ameer Fawad

2018-05-01

Bacterial infection poses life-threatening challenge to humanity and stimulates to the researchers for developing better diagnostic and therapeutic agents complying with existing theranostic techniques. Nuclear medicine technique helps to visualize hard-to-diagnose deep-seated bacterial infections using radionuclide-labeled tracer agents. Metronidazole is an antiprotozoal antibiotic that serves as a preeminent anaerobic chemotherapeutic agent. The aim of this study was to develop technetium-99m-labeled metronidazole radiotracer for the detection of deep-seated bacterial infections. Radiosynthesis of 99m Tc-metronidazole was carried by reacting reduced technetium-99m and metronidazole at neutral pH for 30 min. The stannous chloride dihydrate was used as the reducing agent. At optimum radiolabeling conditions, ~ 94% radiochemical was obtained. Quality control analysis was carried out with a chromatographic paper and instant thin-layer chromatographic analysis. The biodistribution study of radiochemical was performed using Escherichia coli bacterial infection-induced rat model. The scintigraphic study was performed using E. coli bacterial infection-induced rabbit model. The results showed promising accumulation at the site of infection and its rapid clearance from the body. The tracer showed target-to-non-target ratio 5.57 ± 0.04 at 1 h post-injection. The results showed that 99m Tc-MNZ has promising potential to accumulate at E. coli bacterial infection that can be used for E. coli infection imaging.

A Comparison of Antibacterial Activity of Selected Thyme (Thymus) Species by Means of the Dot Blot Test with Direct Bioautographic Detection.

PubMed

Orłowska, Marta; Kowalska, Teresa; Sajewicz, Mieczysław; Jesionek, Wioleta; Choma, Irena M; Majer-Dziedzic, Barbara; Szymczak, Grażyna; Waksmundzka-Hajnos, Monika

2015-01-01

Bioautography carried out with the aid of thin-layer chromatographic adsorbents can be used to assess antibacterial activity in samples of different origin. It can either be used as a simple and cost-effective detection method applied to a developed chromatogram, or to the dot blot test performed on a chromatographic plate, where total antibacterial activity of a sample is scrutinized. It was an aim of this study to compare antibacterial activity of 18 thyme (Thymus) specimens and species (originating from the same gardening plot and harvested in the same period of time) by means of a dot blot test with direct bioautography. A two-step extraction of herbal material was applied, and at step two the polar fraction of secondary metabolites was obtained under the earlier optimized extraction conditions [methanol-water (27+73, v/v), 130°C]. This fraction was then tested for its antibacterial activity against Bacillus subtilis bacteria. It was established that all investigated extracts exhibited antibacterial activity, yet distinct differences were perceived in the size of the bacterial growth inhibition zones among the compared thyme species. Based on the results obtained, T. citriodorus "golden dwarf" (sample No. 5) and T. marschallianus (sample No. 6) were selected as promising targets for further investigations and possible inclusion in a herbal pharmacopeia, which is an essential scientific novelty of this study.

Preparation of porous hollow silica spheres via a layer-by-layer process and the chromatographic performance

NASA Astrophysics Data System (ADS)

Wei, Xiaobing; Gong, Cairong; Chen, Xujuan; Fan, Guoliang; Xu, Xinhua

2017-03-01

Hollow silica spheres possessing excellent mechanical properties were successfully prepared through a layer-by-layer process using uniform polystyrene (PS) latex fabricated by dispersion polymerization as template. The formation of hollow SiO2 micro-spheres, structures and properties were observed in detail by zeta potential, SEM, TEM, FTIR, TGA and nitrogen sorption porosimetry. The results indicated that the hollow spheres were uniform with particle diameter of 1.6 μm and shell thickness of 150 nm. The surface area was 511 m2/g and the pore diameter was 8.36 nm. A new stationary phase for HPLC was obtained by using C18-derivatized hollow SiO2 micro-spheres as packing materials and the chromatographic properties were evaluated for the separation of some regular small molecules. The packed column showed low column pressure, high values of efficiency (up to about 43 000 plates/m) and appropriate asymmetry factors.

Microwave assisted extraction, antioxidant potential and chromatographic studies of some Rasayana drugs.

PubMed

Mishra, Ashish; Mishra, Shilpi; Bhargav, Shilpi; Bhargava, Cs; Thakur, Mayank

2015-07-01

To study and compare the conventional extraction procedure with microwave assisted extraction (MAE) for some Ayurvedic Rasayana drugs and to evaluate their antioxidant potential and carry out the characterization of extracts by thin layer chromatography. Three Ayurvedic rasayana plants Allium sativum Linn., Bombax ceiba Linn. and Inula racemosa Hook. were evaluated for an improved MAE methodology by determining the effects of grinding degree, extraction solvent, effect of dielectric constant and duration of time on the extractive value. Antioxidant potential of all three drugs was evaluated with 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity and reducing power was determined by using Gallic acid as standard. Further thin layer chromatographic (TLC) analysis was performed on pre-activated Silica Gel G plates and Rf value were compared with those reported for the important biomarkers. The total extractive value for Allium sativum Linn. was 36.95% (w/w) and 49.95% (w/w) for ethanol extraction respectively. In case of Bombax ceiba Linn. the yield of aqueous extract by MAE was 50% (w/w) compared to 42% (w/w) in ethanol (50% v/v). Percent yield of Inula racemosa Hook. in aqueous extract was found to be 27.55% (w/w) which was better than ethanol extract (50%) where the yield was 25.95% (w/w). Upon antioxidant activity evaluation. sativum extract showed an absorbance of 0.980±0.92 at concentration of 500 μg with maximum reducing capacity. This was followed by. ceiba Linn. 0.825±0.98 and. racemosa Hook. with 0.799±2.01 at a concentration of 500 μg. TLC based standardization of. sativum Linn. extract shows single spot with Rf value of 0.38, B. ceiba Linn. extract shows Rf values were 0.23, 0.58, 0.77, 0.92 and I. racemosa Hook. extract spot had a Rf value of 0.72. A significant improvement in extractive values was observed as a factor of time and other advantages by using MAE technology. All three drugs have high antioxidant potential and a TLC profiling similar to reported ones. The presence of fructan type polysaccharide can be further utilized for bioactivity directed fractionation and evaluation of immunomodulatory activity.

Low stress polysilicon film and method for producing same

NASA Technical Reports Server (NTRS)

Heuer, Arthur H. (Inventor); Kahn, Harold (Inventor); Yang, Jie (Inventor)

2001-01-01

Multi-layer assemblies of polysilicon thin films having predetermined stress characteristics and techniques for forming such assemblies are disclosed. In particular, a multi-layer assembly of polysilicon thin film may be produced that has a stress level of zero, or substantially so. The multi-layer assemblies comprise at least one constituent thin film having a tensile stress and at least one constituent thin film having a compressive stress. The thin films forming the multi-layer assemblies may be disposed immediately adjacent to one another without the use of intermediate layers between the thin films.

Low stress polysilicon film and method for producing same

NASA Technical Reports Server (NTRS)

Heuer, Arthur H. (Inventor); Kahn, Harold (Inventor); Yang, Jie (Inventor)

2002-01-01

Multi-layer assemblies of polysilicon thin films having predetermined stress characteristics and techniques for forming such assemblies are disclosed. In particular, a multi-layer assembly of polysilicon thin film may be produced that has a stress level of zero, or substantially so. The multi-layer assemblies comprise at least one constituent thin film having a tensile stress and at least one constituent thin film having a compressive stress. The thin films forming the multi-layer assemblies may be disposed immediately adjacent to one another without the use of intermediate layers between the thin films.

Patch testing with thin-layer chromatograms of chamomile tea in patients allergic to sesquiterpene lactones.

PubMed

Lundh, Kerstin; Gruvberger, Birgitta; Möller, Halvor; Persson, Lena; Hindsén, Monica; Zimerson, Erik; Svensson, Ake; Bruze, Magnus

2007-10-01

Patients with contact allergy to sesquiterpene lactones (SLs) are usually hypersensitive to Asteraceae plant products such as herbal teas. The objective of this study was to show sensitizers in chamomile tea by patch testing with thin-layer chromatograms. Tea made from German chamomile was separated by thin-layer chromatography. Strips of the thin-layer chromatograms were used for patch testing SL-positive patients. 15 (43%) of 35 patients tested positively to 1 or more spots on the thin-layer chromatogram, with many individual reaction patterns. Patch testing with thin-layer chromatograms of German chamomile tea showed the presence of several allergens.

Design of experiment assisted concurrent enantioseparation of bupropion and hydroxybupropion by high-performance thin-layer chromatography.

PubMed

Bhatt, Nejal M; Chavada, Vijay D; Sanyal, Mallika; Shrivastav, Pranav S

2017-02-01

A simple and efficient high-performance thin-layer chromatographic method was developed for chiral separation of rac-bupropion (BUP) and its active metabolite rac-hydroxybupropion (HBUP). Design of experiment (DoE)-based optimization was adopted instead of a conventional trial-and-error approach. The Box-Behnken design surface response model was used and the operating variables were optimized based on 17 trials design. The optimized method involved impregnation of chiral reagent, L(+)-tartaric acid, in the stationary phase with simultaneous addition in the mobile phase, which consisted of acetonitrile : methanol : dichloromethane : 0.50% L-tartaric acid (6.75:1.0:1.0:0.25, v/v/v/v). Under the optimized conditions, the resolution factor between the enantiomers of BUP and HBUP was 6.30 and 9.26, respectively. The limit of detection and limit of quantitation for (R)-BUP, (S)-BUP, (R,R)-HBUP, and (S,S)-HBUP were 9.23 and 30.78 ng spot -1 , 10.32 and 34.40 ng spot -1 , 12.19 and 40.65 ng spot -1 , and 14.26 and 47.53 ng spot -1 , respectively. The interaction of L-tartaric acid with analytes and their retention behavior was thermodynamically investigated using van't Hoff's plots. The developed method was validated as per the International Conference on Harmonization guidelines. Finally, the method was successfully applied to resolve and quantify the enantiomeric content from marketed tablets as well as spiked plasma samples. © 2016 Wiley Periodicals, Inc.

Analysis of Wilhelm Ostwald's "Colour Organ" with Raman microspectroscopy

NASA Astrophysics Data System (ADS)

Bridarolli, Alexandra; Atak, Sefkan; Herm, Christoph

2016-11-01

The "Scientific Colour Organ" is a collection of 680 pigment powders, created by the chemist Wilhelm Ostwald in 1925 as a means to represent his colour system. Today, it remains a leading part of colour theory. Analysis of these materials was undertaken to understand how the colour system was realised and to gain indications for preservation of the collection to which it belongs. Dispersive Raman microspectroscopy was applied directly to the powders, as well as using alternative techniques to suppress fluorescence. Barium sulphate was detected in all of the samples with one exception. Portable X-ray fluorescence revealed that this compound was a constituent of lithopone pigment. Raman spectroscopy furthermore revealed synthetic ultramarine (C.I. PB 29) as well as six different synthetic organic pigments and dyes (C.I. PY3; C.I. PO5; C.I. PR81:1; C.I. PV2 and two different triarylmethane dyes). Thin-layer chromatography was applied to determine the exact combination of dyes causing the gradual change in colour of each powder compared to the adjacent samples. With the exception of triarylmethane, the synthetic organic dyes could be identified with Raman spectroscopy directly on the chromatographic plate. The efficiency of thin-layer chromatography combined with Raman spectroscopy for identification of organic pigments could thus be shown. X-ray fluorescence indicated the presence of tungsten-molybdenum lakes in some samples. Comparison of the analytical results to information published by Oswald in 1917 showed that he switched to more light-stable synthetic organic pigments used for his "Scientific Colour Organ".

Development and Validation of a High-Performance Thin-Layer Chromatographic Method for the Simultaneous Determination of Two Binary Mixtures Containing Ketorolac Tromethamine with Phenylephrine Hydrochloride and with Febuxostat

PubMed Central

El Yazbi, Fawzy A.; Hassan, Ekram M.; Khamis, Essam F.; Ragab, Marwa A.A.; Hamdy, Mohamed M.A.

2016-01-01

A validated and highly selective high-performance thin-layer chromatography (HPTLC) method was developed for the determination of ketorolac tromethamine (KTC) with phenylephrine hydrochloride (PHE) (Mixture 1) and with febuxostat (FBX) (Mixture 2) in bulk drug and in combined dosage forms. The proposed method was based on HPTLC separation of the drugs followed by densitometric measurements of their spots at 273 and 320 nm for Mixtures 1 and 2, respectively. The separation was carried out on Merck HPTLC aluminum sheets of silica gel 60 F254 using chloroform–methanol–ammonia (7:3:0.1, v/v) and (7.5:2.5:0.1, v/v) as mobile phase for KTC/PHE and KTC/FBX mixtures, respectively. Linear regression lines were obtained over the concentration ranges 0.20–0.60 and 0.60–1.95 µg band−1 for KTC and PHE (Mixture 1), respectively, and 0.10–1.00 and 0.25–2.50 µg band−1 for KTC and FBX (Mixture 2), respectively, with correlation coefficients higher than 0.999. The method was successfully applied to the analysis of the two drugs in their synthetic mixtures and in their dosage forms. The mean percentage recoveries were in the range of 98–102%, and the RSD did not exceed 2%. The method was validated according to ICH guidelines and showed good performances in terms of linearity, sensitivity, precision, accuracy and stability. PMID:26847918

Amorphous silicon Schottky barrier solar cells incorporating a thin insulating layer and a thin doped layer

DOEpatents

Carlson, David E.

1980-01-01

Amorphous silicon Schottky barrier solar cells which incorporate a thin insulating layer and a thin doped layer adjacent to the junction forming metal layer exhibit increased open circuit voltages compared to standard rectifying junction metal devices, i.e., Schottky barrier devices, and rectifying junction metal insulating silicon devices, i.e., MIS devices.

Effects of channel thickness on oxide thin film transistor with double-stacked channel layer

NASA Astrophysics Data System (ADS)

Lee, Kimoon; Kim, Yong-Hoon; Yoon, Sung-Min; Kim, Jiwan; Oh, Min Suk

2017-11-01

To improve the field effect mobility and control the threshold voltage ( V th ) of oxide thin film transistors (TFTs), we fabricated the oxide TFTs with double-stacked channel layers which consist of thick Zn-Sn-O (ZTO) and very thin In-Zn-O (IZO) layers. We investigated the effects of the thickness of thin conductive layer and the conductivity of thick layer on oxide TFTs with doublestacked channel layer. When we changed the thickness of thin conductive IZO channel layer, the resistivity values were changed. This resistivity of thin channel layer affected on the saturation field effect mobility and the off current of TFTs. In case of the thick ZTO channel layer which was deposited by sputtering in Ar: O2 = 10: 1, the device showed better performances than that which was deposited in Ar: O2 = 1: 1. Our TFTs showed high mobility ( μ FE ) of 40.7 cm2/Vs and V th of 4.3 V. We assumed that high mobility and the controlled V th were caused by thin conductive IZO layer and thick stable ZTO layer. Therefore, this double-stacked channel structure can be very promising way to improve the electrical characteristics of various oxide thin film transistors.

Depositing bulk or micro-scale electrodes

DOEpatents

Shah, Kedar G.; Pannu, Satinderpall S.; Tolosa, Vanessa; Tooker, Angela C.; Sheth, Heeral J.; Felix, Sarah H.; Delima, Terri L.

2016-11-01

Thicker electrodes are provided on microelectronic device using thermo-compression bonding. A thin-film electrical conducting layer forms electrical conduits and bulk depositing provides an electrode layer on the thin-film electrical conducting layer. An insulating polymer layer encapsulates the electrically thin-film electrical conducting layer and the electrode layer. Some of the insulating layer is removed to expose the electrode layer.

Method for bonding thin film thermocouples to ceramics

DOEpatents

Kreider, Kenneth G.

1993-01-01

A method is provided for adhering a thin film metal thermocouple to a ceramic substrate used in an environment up to 700 degrees Centigrade, such as at a cylinder of an internal combustion engine. The method includes the steps of: depositing a thin layer of a reactive metal on a clean ceramic substrate; and depositing thin layers of platinum and a platinum-10% rhodium alloy forming the respective legs of the thermocouple on the reactive metal layer. The reactive metal layer serves as a bond coat between the thin noble metal thermocouple layers and the ceramic substrate. The thin layers of noble metal are in the range of 1-4 micrometers thick. Preferably, the ceramic substrate is selected from the group consisting of alumina and partially stabilized zirconia. Preferably, the thin layer of reactive metal is in the range of 0.015-0.030 micrometers (15-30 nanometers) thick. The preferred reactive metal is chromium. Other reactive metals may be titanium or zirconium. The thin layer of reactive metal may be deposited by sputtering in ultra high purity argon in a vacuum of approximately 2 milliTorr (0.3 Pascals).

Multi-layer assemblies with predetermined stress profile and method for producing same

NASA Technical Reports Server (NTRS)

Heuer, Arthur H. (Inventor); Kahn, Harold (Inventor); Yang, Jie (Inventor); Phillips, Stephen M. (Inventor)

2003-01-01

Multi-layer assemblies of polysilicon thin films having predetermined stress characteristics and techniques for forming such assemblies are disclosed. In particular, a multi-layer assembly of polysilicon thin films may be produced that has a stress level of zero, or substantially so. The multi-layer assemblies comprise at least one constituent thin film having a tensile stress and at least one constituent thin film having a compressive stress. The thin films forming the multi-layer assemblies may be disposed immediately adjacent to one another without the use of intermediate layers between the thin films. Multi-layer assemblies exhibiting selectively determinable overall bending moments are also disclosed. Selective production of overall bending moments in microstructures enables manufacture of such structures with a wide array of geometrical configurations.

Optical Properties of Hybrid Inorganic/Organic Thin Film Encapsulation Layers for Flexible Top-Emission Organic Light-Emitting Diodes.

PubMed

An, Jae Seok; Jang, Ha Jun; Park, Cheol Young; Youn, Hongseok; Lee, Jong Ho; Heo, Gi-Seok; Choi, Bum Ho; Lee, Choong Hun

2015-10-01

Inorganic/organic hybrid thin film encapsulation layers consist of a thin Al2O3 layer together with polymer material. We have investigated optical properties of thin film encapsulation layers for top-emission flexible organic light-emitting diodes. The transmittance of hybrid thin film encapsulation layers and the electroluminescent spectrum of organic light-emitting diodes that were passivated by hybrid organic/inorganic thin film encapsulation layers were also examined as a function of the thickness of inorganic Al203 and monomer layers. The number of interference peaks, their intensity, and their positions in the visible range can be controlled by varying the thickness of inorganic Al2O3 layer. On the other hand, changing the thickness of monomer layer had a negligible effect on the optical properties. We also verified that there is a trade-off between transparency in the visible range and the permeation of water vapor in hybrid thin film encapsulation layers. As the number of dyads decreased, optical transparency improved while the water vapor permeation barrier was degraded. Our study suggests that, in top-emission organic light-emitting diodes, the thickness of each thin film encapsulation layer, in particular that of the inorganic layer, and the number of dyads should be controlled for highly efficient top-emission flexible organic light-emitting diodes.

Composite polymeric film and method for its use in installing a very-thin polymeric film in a device

DOEpatents

Duchane, D.V.; Barthell, B.L.

1982-04-26

A composite polymeric film and a method for its use in forming and installing a very thin (< 10 ..mu..m) polymeric film are disclosed. The composite film consists of a thin film layer and a backing layer. The backing layer is soluble in a solvent in which the thin film layer is not soluble. In accordance with the method, the composite film is installed in a device in the same position in which it is sought to finally emplace the thin film. The backing layer is then selectiely dissolved in the solvent to leave the insoluble thin film layer as an unbacked film. The method permits a very thin film to e successfully installed in devices where the fragility of the film would preclude handling and installation by conventional methods.

Composite polymeric film and method for its use in installing a very thin polymeric film in a device

DOEpatents

Duchane, David V.; Barthell, Barry L.

1984-01-01

A composite polymeric film and a method for its use in forming and installing a very thin (<10 .mu.m) polymeric film are disclosed. The composite film consists of a thin film layer and a backing layer. The backing layer is soluble in a solvent in which the thin film layer is not soluble. In accordance with the method, the composite film is installed in a device in the same position in which it is sought to finally emplace the thin film. The backing layer is then selectively dissolved in the solvent to leave the insoluble thin film layer as an unbacked film. The method permits a very thin film to be successfully installed in devices where the fragility of the film would preclude handling and installation by conventional methods.

Multi-layered, chemically bonded lithium-ion and lithium/air batteries

DOEpatents

Narula, Chaitanya Kumar; Nanda, Jagjit; Bischoff, Brian L; Bhave, Ramesh R

2014-05-13

Disclosed are multilayer, porous, thin-layered lithium-ion batteries that include an inorganic separator as a thin layer that is chemically bonded to surfaces of positive and negative electrode layers. Thus, in such disclosed lithium-ion batteries, the electrodes and separator are made to form non-discrete (i.e., integral) thin layers. Also disclosed are methods of fabricating integrally connected, thin, multilayer lithium batteries including lithium-ion and lithium/air batteries.

Fabrication of low-temperature solid oxide fuel cells with a nanothin protective layer by atomic layer deposition

PubMed Central

2013-01-01

Anode aluminum oxide-supported thin-film fuel cells having a sub-500-nm-thick bilayered electrolyte comprising a gadolinium-doped ceria (GDC) layer and an yttria-stabilized zirconia (YSZ) layer were fabricated and electrochemically characterized in order to investigate the effect of the YSZ protective layer. The highly dense and thin YSZ layer acted as a blockage against electron and oxygen permeation between the anode and GDC electrolyte. Dense GDC and YSZ thin films were fabricated using radio frequency sputtering and atomic layer deposition techniques, respectively. The resulting bilayered thin-film fuel cell generated a significantly higher open circuit voltage of approximately 1.07 V compared with a thin-film fuel cell with a single-layered GDC electrolyte (approximately 0.3 V). PMID:23342963

Chromatographic matrix based on hydrogel-coated reticulated polyurethane foams, prepared by gamma irradiation

NASA Astrophysics Data System (ADS)

Sánchez, Mirna L.; Giménez, Claudia Y.; Delgado, Juan F.; Martínez, Leandro J.; Grasselli, Mariano

2017-12-01

Novel chromatographic materials for protein purification with high adsorption capacity and fouling resistance are highly demanded to improve downstream processes. Here, we describe a novel adsorptive material based on reticulated polyurethane foam (rPUF) coated with a functional hydrogel layer. rPUF provides physical rigidity through its macroscopic structure, whereas the hydrogel layer provides capacity to adsorb proteins by specific interactions. The hydrogel coating process was performed by the dip-coating method, using a polyvinyl alcohol (PVA) solution. The PVA hydrogel was linked to the rPUF material by using a radiation-induced crosslinking process in aqueous ethanol solution. The ethanol in the solvent mixture allowed a balance between PVA swelling and PVA dissolution during the irradiation step. The resulting material showed higher thermal stability than the non-irradiated one. In addition, a simultaneous radiation-induced grafting polymerization (SRIGP) was done by simple addition of glycidyl methacrylate monomer into the irradiation solution. In a further step, sulfonic ligands were included specifically in the hydrogel layer, which contained around 200% of PVA respect to the original rPUF. Materials were characterized by FT-IR, thermogravimetric analysis, SEM microscopy and EDX analysis. The cation-exchange rPUF material was functionally characterized by the Langmuir isotherm and a dynamic adsorption experiment to analyze the chromatographic properties for protein purification processes.

Thin film electronic devices with conductive and transparent gas and moisture permeation barriers

DOEpatents

Simpson, Lin Jay

2015-07-28

Thin film electronic devices (or stacks integrated with a substrate) that include a permeation barrier formed of a thin layer of metal that provides a light transmitting and electrically conductive layer, wherein the electrical conductive layer is formed on a surface of the substrate or device layer such as a transparent conducting material layer with pin holes or defects caused by manufacturing and the thin layer of metal is deposited on the conductive layer and formed from a self-healing metal that forms self-terminating oxides. A permeation plug or block is formed in or adjacent to the thin film of metal at or proximate to the pin holes to block further permeation of contaminants through the pin holes.

Large area polysilicon films with predetermined stress characteristics and method for producing same

NASA Technical Reports Server (NTRS)

Heuer, Arthur H. (Inventor); Kahn, Harold (Inventor); Yang, Jie (Inventor); Phillips, Stephen M. (Inventor)

2002-01-01

Multi-layer assemblies of polysilicon thin films having predetermined stress characteristics and techniques for forming such assemblies are disclosed. In particular, a multi-layer assembly of polysilicon thin films may be produced that has a stress level of zero, or substantially so. The multi-layer assemblies comprise at least one constituent thin film having a tensile stress and at least one constituent thin film having a compressive stress. The thin films forming the multi-layer assemblies may be disposed immediately adjacent to one another without the use of intermediate layers between the thin films. Multi-layer assemblies exhibiting selectively determinable overall bending moments are also disclosed. Selective production of overall bending moments in microstructures enables manufacture of such structures with a wide array of geometrical configurations.

Comparison Between Navier-Stokes and Thin-Layer Computations for Separated Supersonic Flow

NASA Technical Reports Server (NTRS)

Degani, David; Steger, Joseph L.

1983-01-01

In the numerical simulation of high Reynolds-number flow, one can frequently supply only enough grid points to resolve the viscous terms in a thin layer. As a consequence, a body-or stream-aligned coordinate system is frequently used and viscous terms in this direction are discarded. It is argued that these terms cannot be resolved and computational efficiency is gained by their neglect. Dropping the streamwise viscous terms in this manner has been termed the thin-layer approximation. The thin-layer concept is an old one, and similar viscous terms are dropped, for example, in parabolized Navier-Stokes schemes. However, such schemes also make additional assumptions so that the equations can be marched in space, and such a restriction is not usually imposed on a thin-layer model. The thin-layer approximation can be justified in much the same way as the boundary-layer approximation; it requires, therefore, a body-or stream-aligned coordinate and a high Reynolds number. Unlike the boundary-layer approximation, the same equations are used throughout, so there is no matching problem. Furthermore, the normal momentum equation is not simplified and the convection terms are not one-sided differenced for marching. Consequently, the thin-layer equations are numerically well behaved at separation and require no special treatment there. Nevertheless, the thin-layer approximation receives criticism. It has been suggested that the approximation is invalid at separation and, more recently, that it is inadequate for unsteady transonic flow. Although previous comparisons between the thin-layer and Navier-Stokes equations have been made, these comparisons have not been adequately documented.

Multilayer composites and manufacture of same

DOEpatents

Holesinger, Terry G.; Jia, Quanxi

2006-02-07

The present invention is directed towards a process of depositing multilayer thin films, disk-shaped targets for deposition of multilayer thin films by a pulsed laser or pulsed electron beam deposition process, where the disk-shaped targets include at least two segments with differing compositions, and a multilayer thin film structure having alternating layers of a first composition and a second composition, a pair of the alternating layers defining a bi-layer wherein the thin film structure includes at least 20 bi-layers per micron of thin film such that an individual bi-layer has a thickness of less than about 100 nanometers.

Insecticidal components from field pea extracts: isolation and separation of peptide mixtures related to pea albumin 1b.

PubMed

Taylor, Wesley G; Fields, Paul G; Elder, James L

2004-12-15

Chromatographic fractionation of crude extracts (C8 extracts) from the protein-enriched flour of commercial field peas (Pisum sativum L.) has been shown here to yield peptide mixtures related to the pea albumin 1b (PA1b) family of cysteine-rich plant peptides. The mixtures were obtained initially by flash chromatography with silica gel. Following elution of soyasaponins and lysolecithins, the end fractions obtained with the use of two flash chromatographic solvent systems displayed activity in a flour disk antifeedant bioassay with the rice weevil [Sitophilus oryzae (L.)]. Chemical properties of these mixtures were compared by thin-layer chromatography, high-performance liquid chromatography (HPLC), IR, MS, and amino acid analyses. The major peptides of C8 extracts, with average masses of 3752, 3757, and 3805 Da, were isolated by anion exchange chromatography. Samples enriched in the peptide of mass 3752 were isolated by cation exchange chromatography. Reduction plus alkylation experiments in combination with electrospray ionization mass spectrometry showed that C8 extracts contained about 10 peptides and, like PA1b, each peptide possessed six cysteine residues (three disulfide bonds). Disulfide bond reduction with 2-mercaptoethanol destroyed the antifeedant activity. The native peptides of C8 extracts were found to be resolved into nine peaks with XTerra HPLC columns operating at alkaline pH. These columns were employed to assess the distribution of pea peptides in the isolated fractions, with photodiode array and electrospray detection.

Simultaneous Determination of Soyasaponins and Isoflavones in Soy (Glycine max L.) Products by HPTLC-densitometry-Multiple Detection.

PubMed

Shawky, Eman; Sallam, Shaimaa M

2017-11-01

A new high-throughput method was developed for the simultaneous analysis of isoflavones and soyasaponnins in Soy (Glycine max L.) products by high-performance thin-layer chromatography with densitometry and multiple detection. Silica gel was used as the stationary phase and ethyl acetate:methanol:water:acetic acid (100:20:16:1, v/v/v/v) as the mobile phase. After chromatographic development, multi-wavelength scanning was carried out by: (i) UV-absorbance measurement at 265 nm for genistin, daidzin and glycitin, (ii) Vis-absorbance measurement at 650 nm for Soyasaponins I and III, after post-chromatographic derivatization with anisaldehyde/sulfuric acid reagent. Validation of the developed method was found to meet the acceptance criteria delineated by ICH guidelines with respect to linearity, accuracy, precision, specificity and robustness. Calibrations were linear with correlation coefficients of >0.994. Intra-day precisions relative standard deviation (RSD)% of all substances in matrix were determined to be between 0.7 and 0.9%, while inter-day precisions (RSD%) ranged between 1.2 and 1.8%. The validated method was successfully applied for determination of the studied analytes in soy-based infant formula and soybean products. The new method compares favorably to other reported methods in being as accurate and precise and in the same time more feasible and cost-effective. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

HPTLC and Spectrophotometric Estimation of Febuxostat and Diclofenac Potassium in Their Combined Tablets.

PubMed

El-Yazbi, Fawzi A; Amin, Omayma A; El-Kimary, Eman I; Khamis, Essam F; Younis, Sameh E

2016-08-01

An accurate, precise, rapid, specific and economic high-performance thin-layer chromatographic (HPTLC) method has been developed for the simultaneous quantitative determination of febuxostat (FEB) and diclofenac potassium (DIC). The chromatographic separation was performed on precoated silica gel 60 GF254 plates with chloroform-methanol 7:3 (v/v) as the mobile phase. The developed plates were scanned and quantified at 289 nm. Experimental conditions including band size, mobile phase composition and chamber-saturation time were critically studied, and the optimum conditions were selected. A satisfactory resolution (Rs = 2.67) with RF 0.48 and 0.69 and high sensitivity with limits of detection of 4 and 7 ng/band for FEB and DIC, respectively, were obtained. In addition, derivative ratio and ratio difference spectrophotometric methods were established for the analysis of such a mixture. All methods were validated as per the ICH guidelines. In the HPTLC method, the calibration plots were linear between 0.01-0.55 and 0.02-0.60 µg/band, for FEB and DIC, respectively. For the spectrophotometric methods, the calibration graphs were linear between 2-14 and 4-18 µg/mL for FEB and DIC, respectively. The simplicity and specificity of the proposed methods suggest their application in quality control analysis of FEB and DIC in their raw materials and tablets. A comparison of the proposed methods with the existing methods is presented. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Ordered organic-organic multilayer growth

DOEpatents

Forrest, Stephen R.; Lunt, Richard R.

2016-04-05

An ordered multilayer crystalline organic thin film structure is formed by depositing at least two layers of thin film crystalline organic materials successively wherein the at least two thin film layers are selected to have their surface energies within .+-.50% of each other, and preferably within .+-.15% of each other, whereby every thin film layer within the multilayer crystalline organic thin film structure exhibit a quasi-epitaxial relationship with the adjacent crystalline organic thin film.

Ordered organic-organic multilayer growth

DOEpatents

Forrest, Stephen R; Lunt, Richard R

2015-01-13

An ordered multilayer crystalline organic thin film structure is formed by depositing at least two layers of thin film crystalline organic materials successively wherein the at least two thin film layers are selected to have their surface energies within .+-.50% of each other, and preferably within .+-.15% of each other, whereby every thin film layer within the multilayer crystalline organic thin film structure exhibit a quasi-epitaxial relationship with the adjacent crystalline organic thin film.

Nano-crystalline thin and nano-particulate thick TiO{sub 2} layer: Cost effective sequential deposition and study on dye sensitized solar cell characteristics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Das, P.; Sengupta, D.; CSIR-Central Mechanical Engineering Research Institute, Academy of Scientific and Innovative Research

Highlights: • Thin TiO{sub 2} layer is deposited on conducting substrate using sol–gel based dip coating. • TiO{sub 2} nano-particles are synthesized using hydrothermal route. • Thick TiO{sub 2} particulate layer is deposited on prepared thin layer. • Dye sensitized solar cells are made using thin and thick layer based photo-anode. • Introduction of thin layer in particulate photo-anode improves the cell efficiency. - Abstract: A compact thin TiO{sub 2} passivation layer is introduced between the mesoporous TiO{sub 2} nano-particulate layer and the conducting glass substrate to prepare photo-anode for dye-sensitized solar cell (DSSC). In order to understand the effectmore » of passivation layer, other two DSSCs are also developed separately using TiO{sub 2} nano-particulate and compact thin film based photo-anodes. Nano-particles are prepared using hydrothermal synthesis route and the compact passivation layer is prepared by simply dip coating the precursor sol prepared through wet chemical route. The TiO{sub 2} compact layer and the nano-particles are characterised in terms of their micro-structural features and phase formation behavior. It is found that introduction of a compact TiO{sub 2} layer in between the mesoporous TiO{sub 2} nano-particulate layer and the conducting substrate improves the solar to electric conversion efficiency of the fabricated cell. The dense thin passivation layer is supposed to enhance the photo-excited electron transfer and prevent the recombination of photo-excited electrons.« less

Rapid planar chromatographic analysis of 25 water-soluble dyes used as food additives.

PubMed

Morlock, Gertrud E; Oellig, Claudia

2009-01-01

A rapid planar chromatographic method for identification and quantification of 25 water-soluble dyes in food was developed. In a horizontal developing chamber, the chromatographic separation on silica gel 60F254 high-performance thin-layer chromatography plates took 12 min for 40 runs in parallel, using 8 mL ethyl acetate-methanol-water-acetic acid (65 + 23 + 11 + 1, v/v/v/v) mobile phase up to a migration distance of 50 mm. However, the total analysis time, inclusive of application and evaluation, took 60 min for 40 runs. Thus, the overall time/run can be calculated as 1.5 min with a solvent consumption of 200 microL. A sample throughput of 1000 runs/8 h day can be reached by switching between the working stations (application, development, and evaluation) in a 20 min interval, which triples the analysis throughput. Densitometry was performed by absorption measurement using the multiwavelength scan mode in the UV and visible ranges. Repeatabilities [relative standard deviation (RSD), 4 determinations] at the first or second calibration level showed precisions of mostly < or = 2.7%, ranging between 0.2 and 5.2%. Correlation coefficient values (R > or = 0.9987) and RSD values (< or = 4.2%) of the calibration curves were highly satisfactory using classical quantification. However, digital evaluation of the plate image was also used for quantification, which resulted in RSD values of the calibration curves of mostly < or = 3.0%, except for two < or = 6.0%. The method was applied for the analysis of some energy drinks and bakery ink formulations, directly applied after dilution. By recording of absorbance spectra in the visible range, the identities of the dyes found in the samples were ascertained by comparison with the respective standard bands (correlation coefficients > or = 0.9996). If necessary for confirmation, online mass spectra were recorded within a minute.

Stability-indicating chromatographic methods for the determination of some oxicams.

PubMed

Taha, Elham Anwer; Salama, Nahla Nour; Abdel Fattah, Laila el-Said

2004-01-01

Two sensitive and selective methods were developed for the determination of some oxicams, namely, lornoxicam (LOX), tenoxicam (TEX), and meloxicam (MEX), in the presence of their alkaline degradation products. The first method is based on the thin-layer chromatographic separation of the 3 drugs from their alkaline degradation products, followed by densitometric measurement of the intact drug spots for LOX, TEX, and MEX at 380, 370, and 364 nm, respectively. The developing systems used for separation are ethyl acetate-methanol-26% ammonia (17 + 3 + 0.35, v/v/v) for LOX and TEX and chloroform-n-hexane-96.0% acetic acid (18 + 1 + 1, v/v/v) for MEX. The linear ranges were 0.25-6.0 microg/spot for LOX and TEX and 0.5-10 microg/spot for MEX, with mean recoveries of 99.80 +/- 1.32, 100.57 +/- 1.34, and 100.71 +/- 1.57%, respectively. The second method is based on the liquid chromatographic separation of the 3 drugs from their alkaline degradation products on a reversed-phase C18 column, using mobile phases of methanol-acetonitrile-acetate buffer, pH 4.6 (4.5 + 0.5 + 5.0, v/v/v) for LOX and MEX and methanol-acetonitrile-acetate buffer, pH 4.6 (1.9 + 0.1 + 3.0, v/v/v) for TEX at ambient temperature. Quantification is achieved by UV detection at 280 nm, based on peak area. The linear ranges were 0.5-20 microg/mL for LOX and TEX and 1.25-50 microg/mL for MEX, with mean recoveries of 99.81 +/- 1.01, 98.90 +/- 1.61, and 100.86 +/- 1.55%, respectively. The methods were validated according to guidelines of the International Conference on Harmonization. The developed methods were successfully applied to the determination of LOX, TEX, and MEX in bulk powder, laboratory-prepared mixtures containing different percentages of degradation products, and pharmaceutical dosage forms.

An Electrochemical Experiment Using an Optically Transparent Thin Layer Electrode

ERIC Educational Resources Information Center

DeAngelis, Thomas P.; Heineman, William R.

1976-01-01

Describes a unified experiment in which an optically transparent thin layer electrode is used to illustrate the techniques of thin layer electrochemistry, cyclic voltammetry, controlled potential coulometry, and spectroelectrochemistry. (MLH)

Rectenna that converts infrared radiation to electrical energy

DOEpatents

Davids, Paul; Peters, David W.

2016-09-06

Technologies pertaining to converting infrared (IR) radiation to DC energy are described herein. In a general embodiment, a rectenna comprises a conductive layer. A thin insulator layer is formed on the conductive layer, and a nanoantenna is formed on the thin insulator layer. The thin insulator layer acts as a tunnel junction of a tunnel diode.

Cadmium-free junction fabrication process for CuInSe.sub.2 thin film solar cells

DOEpatents

Ramanathan, Kannan V.; Contreras, Miguel A.; Bhattacharya, Raghu N.; Keane, James; Noufi, Rommel

1999-01-01

The present invention provides an economical, simple, dry and controllable semiconductor layer junction forming process to make cadmium free high efficiency photovoltaic cells having a first layer comprised primarily of copper indium diselenide having a thin doped copper indium diselenide n-type region, generated by thermal diffusion with a group II(b) element such as zinc, and a halide, such as chlorine, and a second layer comprised of a conventional zinc oxide bilayer. A photovoltaic device according the present invention includes a first thin film layer of semiconductor material formed primarily from copper indium diselenide. Doping of the copper indium diselenide with zinc chloride is accomplished using either a zinc chloride solution or a solid zinc chloride material. Thermal diffusion of zinc chloride into the copper indium diselenide upper region creates the thin n-type copper indium diselenide surface. A second thin film layer of semiconductor material comprising zinc oxide is then applied in two layers. The first layer comprises a thin layer of high resistivity zinc oxide. The second relatively thick layer of zinc oxide is doped to exhibit low resistivity.

A chromatographic analysis of the response of polymeric fire-detection devices to combustion products

NASA Technical Reports Server (NTRS)

Senturia, S. D.

1977-01-01

Polymer responses to a variety of smouldering sources, including cellulose, acrylic, urethane, polyvinyl chloride, and wool were investigated. A suitable trapping system for combustion products was developed and a charge flow transistor was fabricated to monitor the transverse or sheet resistance of a thin film.

Radiometric assay for phenylethanolamine N-methyltransferase and catechol O-methyltransferase in a single tissue sample: application to rat hypothalamic nuclei, pineal gland, and heart

DOE Office of Scientific and Technical Information (OSTI.GOV)

Culman, J.; Torda, T.; Weise, V.K.

A simple and highly sensitive method for simultaneous assay of phenylethanolamine N-methyltransferase (PNMT) and catechol O-methyltransferase (COMT) is described. These enzymes are determined in a single tissue homogenate using S-(methyl-/sup 3/H) adenosyl-L-methionine as methyl donor and sequentially incubating with the substrates phenylethanolamine and epinephrine. The radioactive products of the enzymatic reactions, N-methylphenylethanolamine and metanephrine, are extracted and then separated by thin-layer chromatography. The identity of the reaction products has been established chromatographically and the conditions for both enzymatic reactions in the assay procedure have been defined. Measurement of PNMT activity in the rat pineal gland or in minute fragments ofmore » other tissues (e.g., brain nuclei) has not been possible using previously described methods. Activities of PNMT and COMT in the rat pineal gland, various hypothalamic nuclei, and the auricular and ventricular myocardia are herein reported.« less

[HPTLC fingerprint analysis of andrographolides from Andrographis paniculata].

PubMed

Shao, Yan-Hua; Wang, Jian-Gang; Lai, Xiao-Ping; Wu, Xiang-Wei; Ding, Ping

2014-02-01

To establish the high-performance thin layer chromatography (HPTLC) fingerprint of andrographolides from Andrographis paniculata, and to valuate the fingerprint similarity of samples from different habitats, markets, used parts and so on. Chromatographic conditions were as follows: stationary phase: precoated HPTLC GF254 silica-gel plate (20 cm x 10 cm); developing solvent system: chloroform-toluene-methanol (80:10:15); Relative humidity: 42%; Color development reagent: 5% H2SO4 ethanolic solution, heating at 105 degrees C and observing the fluorescent chromatogram in a UV cabinet at 366 nm. The common patterns of HPTLC fingerprint were obtained through CHROMAP 1.5 solution software. The HPTLC fingerprint of andrographolides was consisted of 9 characteristic peaks (fluorescent bands) including andrographolide, neoandrographolide and dehydroandrographolide which were chemical reference substances. The investigation and analysis of 51 batches of Andrographis paniculata showed that there were remarkable differences among different samples, so was the content of andrographolide and total lactones. This method is simple and rapid, which can serve as an effective identification and quality assessment method for Andrographis paniculata.

QUANTIFICATION OF GLYCYRRHIZIN BIOMARKER IN GLYCYRRHIZA GLABRA RHIZOME AND BABY HERBAL FORMULATIONS BY VALIDATED RP-HPTLC METHODS

PubMed Central

Alam, Prawez; Foudah, Ahmed I.; Zaatout, Hala H.; T, Kamal Y; Abdel-Kader, Maged S.

2017-01-01

Background: A simple and sensitive thin-layer chromatographic method has been established for quantification of glycyrrhizin in Glycyrrhiza glabra rhizome and baby herbal formulations by validated Reverse Phase HPTLC method. Materials and Methods: RP-HPTLC Method was carried out using glass coated with RP-18 silica gel 60 F254S HPTLC plates using methanol-water (7: 3 v/v) as mobile phase. Results: The developed plate was scanned and quantified densitometrically at 256 nm. Glycyrrhizin peaks from Glycyrrhiza glabra rhizome and baby herbal formulations were identified by comparing their single spot at Rf = 0.63 ± 0.01. Linear regression analysis revealed a good linear relationship between peak area and amount of glycyrrhizin in the range of 2000-7000 ng/band. Conclusion: The method was validated, in accordance with ICH guidelines for precision, accuracy, and robustness. The proposed method will be useful to enumerate the therapeutic dose of glycyrrhizin in herbal formulations as well as in bulk drug. PMID:28573236

Column chromatography isolation of nicotine from tobacco leaf extract (Nicotiana tabaccum L.)

NASA Astrophysics Data System (ADS)

Fathi, Raden Muhammad; Fauzantoro, Ahmad; Rahman, Siti Fauziyah; Gozan, Misri

2018-02-01

Restrictions on the use of dried tobacco leaf for cigarette production must be accompanied by the development of non-cigarette alternative products that are made from tobacco leaves. One of the alternative that can be done is to use the nicotine compound in tobacco leaf extract as medical product, such as Parkinson's medication or to be used as active substance in biopesticide. Nicotine was isolated using column chromatography method with the variation of mobile phase mixture ratio (petroleum ether and ethanol), started from 8:2, 6:4, 4:6, 2:8, to 0:10. All of the chromatographic fraction from each mobile phase's ratio was then tested qualitatively using thin layer chromatography (TLC) and also quantitatively using HPLC instrument. The column chromatography process could isolate 4.006% of nicotine compound from 4.19% tobacco leaf extract's nicotine. It is also known that ethanol is a good solution to be used as chromatography's mobile phase for nicotine isolation from tobacco leaf extract.

Does Para-chloroaniline Really Form after Mixing Sodium Hypochlorite and Chlorhexidine?

PubMed

Orhan, Ekim Onur; Irmak, Özgür; Hür, Deniz; Yaman, Batu Can; Karabucak, Bekir

2016-03-01

Mixing sodium hypochlorite (NaOCl) with chlorhexidine (CHX) forms a brown-colored precipitate. Previous studies are not in agreement whether this precipitate contains para-chloroaniline (PCA). Tests used for analysis may demonstrate different outcomes. Purpose of this study was to determine whether PCA is formed through the reaction of mixing NaOCl and CHX by using high performance liquid chromatography, proton nuclear magnetic resonance spectroscopy, gas chromatography, thin layer chromatography, infrared spectroscopy, and gas chromatography/mass spectrometry. To obtain a brown precipitate, 4.99% NaOCl was mixed with 2.0% CHX. This brown precipitate was analyzed and compared with signals obtained from commercially available 4.99% NaOCl, 2% solutions, and 98% PCA in powder form. Chromatographic and spectroscopic analyses showed that brown precipitate does not contain free PCA. This study will be a cutoff proof for the argument on PCA formation from reaction of CHX and NaOCl. Copyright © 2016 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Natural occurrence of the mycotoxin viomellein in barley and the associated quinone-producing penicillia.

PubMed Central

Hald, B; Christensen, D H; Krogh, P

1983-01-01

In a batch of barley associated with field cases of mycotoxic porcine nephropathy and containing ochratoxin A and citrinin, the mycoflora were isolated by parallel incubation at 10 and 25 degrees C. Subsequently, the isolated cultures were checked for production of nephrotoxins (xanthomegnin, viomellein, ochratoxin, and citrinin). The nephrotoxin producers, all isolated by incubation at 10 degrees C, were comprised of one culture of Penicillium viridicatum, five cultures of Penicillium cyclopium, and one culture of Penicillium crustosum, all producing xanthomegnin and viomellein. One culture of P. cyclopium produced citrinin. Viomellein was detected in the barley at a concentration of approximately 1 mg/kg. The method of analysis for xanthomegnin and viomellein included extraction with chloroform, partitioning in hexane-acetone, and thin-layer chromatographic separation and identification. The identity of the xanthomegnin and viomellein produced by the isolated fungi and of viomellein detected in the barley was supported by infrared spectroscopy. This is the first report of viomellein as a natural contaminant of foodstuffs. Images PMID:6660870

Validation of a reversed phase high performance thin layer chromatographic-densitometric method for secoisolariciresinol diglucoside determination in flaxseed.

PubMed

Coran, Silvia A; Bartolucci, Gianluca; Bambagiotti-Alberti, Massimo

2008-10-17

The validation of a HPTLC-densitometric method for the determination of secoisolariciresinol diglucoside (SDG) in flaxseed was performed improving the reproducibility of a previously reported HPTLC densitometric procedure by the use of fully wettable reversed phase plates (silica gel 60 RP18W F(254S), 10cmx10cm) with MeOH:HCOOH 0.1% (40:60, v/v) mobile phase. The analysis required only the alkaline hydrolysis in aqueous medium of undefatted samples and densitometry at 282nm of HPTLC runs. The method was validated following the protocol proposed by the Société Francaise des Sciences et Techniques Pharmaceutiques (SFSTP) giving rise to a dependable and high throughput procedure well suited to routine application. SDG was quantified in the range of 321-1071ng with RSD of repeatability and intermediate precision not exceeding 3.61% and accuracy inside the acceptance limits. Flaxseed of five cultivars of different origin was elected as test-bed.

Assessment of the antioxidant and antibacterial activities of different olive processing wastewaters

PubMed Central

Tan, Shiau Pin; El-Abbassi, Abdelilah; Kiai, Hajar; Hafidi, Abdellatif; O’Donovan, Orla; McLoughlin, Peter

2017-01-01

Olive processing wastewaters (OPW), namely olive mill wastewater (OMW) and table-olive wastewaters (TOW) were evaluated for their antibacterial activity against five Gram-positive and two Gram-negative bacteria using the standard disc diffusion and thin layer chromatography (TLC)-bioautography assays. Disc diffusion screening and bioautography of OMW were compared to the phenolic extracts of table-olive brines. Positive activity against S. aureus was demonstrated. The optimization of chromatographic separation revealed that hexane/acetone in the ratio of 4:6 was the most effective for phenolic compounds separation. A HPLC-MS analysis was performed showing that only two compounds, hydroxytyrosol and tyrosol, were the predominant phenolic compounds in all OPW. The phenolic extract of OMW generated by a semi-modern process showed the highest free radical-scavenging activity (DPPH assay) compared to the other phenolic extracts. It is apparent from the present study that OPW are a rich source of antioxidants suitable for use in food, cosmetic or pharmaceutical applications. PMID:28873097

Mycoflora and mycotoxin-producing fungi of air-dust particles from Egypt.

PubMed

Abdel-Hafez, S I; Shoreit, A A; Abdel-Hafez, A I; el Maghraby, O M

1986-01-01

Using the dilution-plate method, 27 genera and 64 species were collected from 20 air-dust samples on glucose - (24 genera and 57 species) and cellulose - (21 genera and 45 species) Czapek's agar at 28 degrees C. There are basic similarities between the mycoflora of air-dust on the two media and the most prevalent species were Aspergillus niger, A. flavus, A. ochraceus, A. terreus, A. versicolor, Penicillium chrysogenum, P. funiculosum, Alternaria alternata, Cladosporium herbarum, Fusarium oxysporum, Rhizopus stolonifer and Trichoderma viride. Chaetomium globosum, Stachybotrys chartarum, Humicola grisea and Arthrobotrys oligospora were common only on cellulose agar plates. Extracts of mycelium from 25 isolates were tested with brine schrimp (Artemia salina); of these 23 displayed varying degrees of toxicity. Thin layer chromatographic analysis of 12 isolates of Aspergillus flavus revealed that 4 strains were producing detectable aflatoxin. Zearalenone production was noted for 3 out of 5 strains of Fusarium oxysporum and 2 out of 5 strains of F. solani.

The threshold strength of laminar ceramics utilizing molar volume changes and porosity

NASA Astrophysics Data System (ADS)

Pontin, Michael Gene

It has been shown that uniformly spaced thin compressive layers within a ceramic body can arrest the propagation of an otherwise catastrophic crack, producing a threshold strength: a strength below which the probability of failure is zero. Previous work has shown that the threshold strength increases with both the magnitude of the compressive stress and the fracture toughness of the thin layer material, and finite element analysis predicts that the threshold strength can be further increased when the elastic modulus of the compressive layer is much smaller than the thicker layer. The current work describes several new approaches to increase the threshold strength of a laminar ceramic system. The initial method utilized a molar volume expansion within the thin layers, produced by the tetragonal-to-monoclinic phase transformation of unstabilized zirconia during cooling, in order to produce large compressive stresses within the thin layers. High threshold strengths were measured for this system, but they remained relatively constant as the zirconia content was increased. It was determined that microcracking produced during the transformation reduced the magnitude of the compressive stresses, but may also have served to reduce the modulus of the thin compressive layer, providing an additional strengthening mechanism. The second approach studied the addition of porosity to reduce the elastic modulus of the thin compressive layers. A new processing method was created and analyzed, in which thick layers of the laminate were fabricated by tape-casting, and then dip-coated into a slurry, containing rice starch, to create thin porous compressive layers upon densification. The effects of porosity on the residual compressive stress, elastic modulus, and fracture toughness of the thin layers were measured and calculated, and it was found that the elastic modulus mismatch between the thin and thick layers produced a large strengthening effect for volume fractions of porosity below a critical level. Specimens with greater volume fractions of porosity exhibited complete crack arrest, typically followed by non-catastrophic failure, as cracks initiating in adjacent thick layers coalesced by cracking or delamination along the thin porous layers.

Characterization of Cu buffer layers for growth of L10-FeNi thin films

NASA Astrophysics Data System (ADS)

Mizuguchi, M.; Sekiya, S.; Takanashi, K.

2010-05-01

A Cu(001) layer was fabricated on a Au(001) layer to investigate the use of Cu as a buffer layer for growing L10-FeNi thin films. The epitaxial growth of a Cu buffer layer was observed using reflection high-energy electron diffraction. The flatness of the layer improved drastically with an increase in the substrate temperature although the layer was an alloy (AuCu3). An FeNi thin film was epitaxially grown on the AuCu3 buffer layer by alternate monatomic layer deposition and the formation of an L10-FeNi ordered alloy was expected. The AuCu3 buffer layer is thus a promising candidate material for the growth of L10-FeNi thin films.

Toward rapid analysis, forecast and discovery of bioactive compounds from herbs by jointly using thin layer chromatography and ratiometric surface-enhanced Raman spectroscopy technique.

PubMed

Gu, Xiaoling; Jin, Yang; Dong, Fang; Cai, Yueqing; You, Zhengyi; You, Junhui; Zhang, Liying; Du, Shuhu

2018-05-10

Conventional isolation and identification of active compounds from herbs have been extensively reported by using various chromatographic and spectroscopic techniques. However, how to quickly discover new bioactive ingredients from natural sources still remains a challenging task due to the interference of their similar structures or matrices. Here, we present a grand approach for rapid analysis, forecast and discovery of bioactive compounds from herbs based on a hyphenated strategy of thin layer chromatography and ratiometric surface-enhanced Raman spectroscopy. The performance of the hyphenated strategy is first evaluated by analyzing four protoberberine alkaloids, berberine (BER), coptisine (COP), palmatine (PAT) and jatrorrhizine (JAT), from a typical herb Coptidis Rhizoma as an example. It has been demonstrated that this coupling method can identify the four compounds by characteristic peaks at 728, 708, 736 and 732 cm -1 , and especially discriminate BER and COP (with similar migration distances) by ratiometric Raman intensity (I 708 /I 728 ). The corresponding limits of detection are 0.1, 0.05, 0.1 and 0.5 μM, respectively, which are about 1-2 orders of magnitude lower than those of direct observation method under 254 nm UV lamp. Based on these findings, the proposed method further guides forecast and discovery of unknown compounds from traditional Chinese herb Typhonii Rhizoma. Results infer that two trace alkaloids (BER and COP) from the n-butanol extract of Typhonii Rhizoma are found for the first time. Moreover, in vitro experiments manifest that BER can effectively decrease the viability of human glioma U87 cells by inducing cell cycle arrest in a concentration-dependent manner. Copyright © 2018 Elsevier B.V. All rights reserved.

The catabolism of mammalian glycoproteins. Comparison of the storage products in bovine, feline and human mannosidosis.

PubMed

Abraham, D; Blakemore, W F; Jolly, R D; Sidebotham, R; Winchester, B

1983-12-01

Analysis of the neutral urinary oligosaccharides in bovine, feline and human mannosidosis by thin-layer and gel-permeation chromatography has shown that the patterns of stored oligosaccharides in the three species are different. In bovine and feline mannosidosis the most abundant urinary oligosaccharide is also the most abundant in the tissues of each species. The predominant oligosaccharides were purified by a combination of gel-filtration, ion-exchange and thin-layer chromatography and shown to contain only mannose and N-acetylglucosamine by g.l.c. and g.l.c.--mass spectrometry. The probable composition and size of each oligosaccharide were predicted from its chromatographic properties, sugar composition and the known structure of asparagine-linked oligosaccharides. The bovine and feline oligosaccharides belonged to a homologous series of general composition Mann (GlcNAc)2, whereas the human oligosaccharides belong to a different series, MannGlcNAc. These structures suggest that lysosomal endohexosaminidase is not present in bovine and feline tissues. The predominant feline storage product, Man3(GlcNAc)2, was the expected storage product from the catabolism of complex asparagine-linked glycans. In contrast, the predominant bovine oligosaccharide, Man2(GlcNAc)2, probably lacks one of the alpha-linked mannose residues in the core region. A similar situation occurs in human mannosidosis. It is predicted that in these species either that the residual mutant alpha-D-mannosidase retains activity towards one of the core alpha-linked mannose residues or that another form of lysosomal alpha-D-mannosidase that is unaffected in these disorders occurs. It is concluded that the differences in storage products are due to differences in the catabolic pathways of glycoproteins among the species.

Stability-indicating assay of repaglinide in bulk and optimized nanoemulsion by validated high performance thin layer chromatography technique.

PubMed

Akhtar, Juber; Fareed, Sheeba; Aqil, Mohd

2013-07-01

A sensitive, selective, precise and stability-indicating high-performance thin-layer chromatographic (HPTLC) method for analysis of repaglinide both as a bulk drug and in nanoemulsion formulation was developed and validated. The method employed TLC aluminum plates precoated with silica gel 60F-254 as the stationary phase. The solvent system consisted of chloroform/methanol/ammonia/glacial acetic acid (7.5:1.5:0.9:0.1, v/v/v/v). This system was found to give compact spots for repaglinide (R f value of 0.38 ± 0.02). Repaglinide was subjected to acid and alkali hydrolysis, oxidation, photodegradation and dry heat treatment. Also, the degraded products were well separated from the pure drug. Densitometric analysis of repaglinide was carried out in the absorbance mode at 240 nm. The linear regression data for the calibration plots showed good linear relationship with r (2)= 0.998 ± 0.032 in the concentration range of 50-800 ng. The method was validated for precision, accuracy as recovery, robustness and specificity. The limits of detection and quantitation were 0.023 and 0.069 ng per spot, respectively. The drug undergoes degradation under acidic and basic conditions, oxidation and dry heat treatment. All the peaks of the degraded product were resolved from the standard drug with significantly different R f values. Statistical analysis proves that the method is reproducible and selective for the estimation of the said drug. As the method could effectively separate the drug from its degradation products, it can be employed as a stability-indicating one. Moreover, the proposed HPTLC method was utilized to investigate the degradation kinetics in 1M NaOH.

Cyp7b, a novel brain cytochrome P450, catalyzes the synthesis of neurosteroids 7α-hydroxy dehydroepiandrosterone and 7α-hydroxy pregnenolone

PubMed Central

Rose, Ken A.; Stapleton, Genevieve; Dott, Karin; Kieny, Marie Paule; Best, Ruth; Schwarz, Margrit; Russell, David W.; Björkhem, Ingemar; Seckl, Jonathan; Lathe, Richard

1997-01-01

Steroids produced locally in brain (neurosteroids), including dehydroepiandrosterone (DHEA), influence cognition and behavior. We previously described a novel cytochrome P450, Cyp7b, strongly expressed in rat and mouse brain, particularly in hippocampus. Cyp7b is most similar to steroidogenic P450s and potentially could play a role in neurosteroid metabolism. To examine the catalytic activity of the enzyme mouse Cyp7b cDNA was introduced into a vaccinia virus vector. Extracts from cells infected with the recombinant showed NADPH-dependent conversion of DHEA (Km, 13.6 μM) and pregnenolone (Km, 4.0 μM) to slower migrating forms on thin layer chromatography. The expressed enzyme was less active against 25-hydroxycholesterol, 17β-estradiol and 5α-androstane-3β,17β-diol, with low to undetectable activity against progesterone, corticosterone, and testosterone. On gas chromatography and mass spectrometry of the Cyp7b metabolite of DHEA the retention time and fragmentation patterns were identical to those obtained with authentic 7α-hydroxy DHEA. The reaction product also comigrated on thin layer chromatography with 7α-hydroxy DHEA but not with 7β-hydroxy DHEA; when [7α-3H]pregnenolone was incubated with Cyp7b extracts the extent of release of radioactivity into the medium suggested that hydroxylation was preferentially at the 7α position. Brain extracts also efficiently liberated tritium from [7α-3H]pregnenolone and converted DHEA to a product with a chromatographic mobility indistinguishable from 7α-hydroxy DHEA. We conclude that Cyp7b is a 7α-hydroxylase participating in the synthesis, in brain, of neurosteroids 7α-hydroxy DHEA, and 7α-hydroxy pregnenolone. PMID:9144166

/sup 32/P-postlabeling analysis of DNA adducts in liver of wild English sole (Parophrys vetulus) and winter flounder (Pseudopleuronectes americanus)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Varanasi, U.; Reichert, W.L.; Stein, J.E.

The 1-butanol adduct enhancement version of the 32P-postlabeling assay was used to measure the levels of hepatic DNA adducts in the marine flatfish, English sole (Parophrys vetulus), sampled from the Duwamish Waterway and Eagle Harbor, Puget Sound, WA, where they are exposed to high concentrations of sediment-associated chemical contaminants and exhibit an elevated prevalence of hepatic neoplasms. Hepatic DNA was also analyzed from English sole from a reference area (Useless Bay, WA) and from reference English sole treated with organic-solvent extracts of sediments from the two contaminated sites. Autoradiograms of thin-layer chromatograms of 32P-labeled hepatic DNA digests from English solemore » from the contaminated sites exhibited up to three diagonal radioactive zones, which were not present in autoradiograms of thin-layer chromatogram maps of 32P-labeled DNA digests from English sole from the reference site. These diagonal radioactive zones contained several distinct spots as well as what appeared to be multiple overlapping adduct spots. The levels (nmol of adducts/mol of nucleotides) of total DNA adducts for English sole from Duwamish Waterway and Eagle Harbor were 26 +/- 28 (DS) and 17 +/- 9.6, respectively. All autoradiograms of DNA from fish from the contaminated sites exhibited a diagonal radioactive zone where DNA adducts of chrysene, benzo(a)pyrene, and dibenz(a,h)anthracene, formed in vitro using English sole hepatic microsomes, were shown to chromatograph. English sole treated with extracts of the contaminated sediments had adduct profiles generally similar to those for English sole from the respective contaminated sites.« less

Ceramic Composite Thin Films

NASA Technical Reports Server (NTRS)

Dikin, Dmitriy A. (Inventor); Nguyen, SonBinh T. (Inventor); Ruoff, Rodney S. (Inventor); Stankovich, Sasha (Inventor)

2013-01-01

A ceramic composite thin film or layer includes individual graphene oxide and/or electrically conductive graphene sheets dispersed in a ceramic (e.g. silica) matrix. The thin film or layer can be electrically conductive film or layer depending the amount of graphene sheets present. The composite films or layers are transparent, chemically inert and compatible with both glass and hydrophilic SiOx/silicon substrates. The composite film or layer can be produced by making a suspension of graphene oxide sheet fragments, introducing a silica-precursor or silica to the suspension to form a sol, depositing the sol on a substrate as thin film or layer, at least partially reducing the graphene oxide sheets to conductive graphene sheets, and thermally consolidating the thin film or layer to form a silica matrix in which the graphene oxide and/or graphene sheets are dispersed.

Thin-layer voltammetry of soluble species on screen-printed electrodes: proof of concept.

PubMed

Botasini, S; Martí, A C; Méndez, E

2016-10-17

Thin-layer diffusion conditions were accomplished on screen-printed electrodes by placing a controlled-weight onto the cast solution and allowing for its natural spreading. The restricted diffusive conditions were assessed by cyclic voltammetry at low voltage scan rates and electrochemical impedance spectroscopy. The relationship between the weight exerted over the drop and the thin-layer thickness achieved was determined, in such a way that the simple experimental set-up designed for this work could be developed into a commercial device with variable control of the thin-layer conditions. The experimental results obtained resemble those reported for the voltammetric features of electroactive soluble species employing electrodes modified with carbon nanotubes or graphene layers, suggesting that the attainment of the benefits reported for these nanomaterials could be done simply by forcing the solution to spread over the screen-printed electrodic system to form a thin layer solution. The advantages of thin-layer voltammetry in the kinetic characterization of quasi-reversible and irreversible processes are highlighted.

A model for thin layer formation by delayed particle settling at sharp density gradients

NASA Astrophysics Data System (ADS)

Prairie, Jennifer C.; White, Brian L.

2017-02-01

Thin layers - regions where plankton or particles accumulate vertically on scales of a few meters or less - are common in coastal waters, and have important implications for both trophic dynamics and carbon cycling. These features can form by a variety of biological and physical mechanisms, including localized growth, shear-thinning, and directed swimming. An additional mechanism may result in the formation of thin layers of marine aggregates, which have been shown to decrease their settling velocity when passing through sharp density gradients, a behavior termed delayed settling. Here, we apply a simple vertical advection-diffusion model to predict the properties of aggregate thin layers formed by this process. We assume a constant vertical flux of particles from the surface, which is parameterized by observations from laboratory experiments with marine aggregates. The formation, maintenance, and shape of the layers are described in relation to non-dimensional numbers that depend on environmental conditions and particle settling properties. In particular, model results demonstrate layer intensity and sharpness both increase with higher Péclet number (Pe), that is, under conditions with weaker mixing relative to layer formation. Similarly, more intense and sharper layers are found when the delayed settling behavior of aggregates is characterized by a lower velocity minimum. The model also predicts layers that are vertically asymmetric and highly "peaky" when compared with a Gaussian distribution, features often seen in thin layers in natural environments. Lastly, by comparing model predictions with observations of thin layers in the field, we are able to gain some insight into the applicability of delayed settling as a thin layer formation mechanism in different environmental conditions.

Thin Film Transistors On Plastic Substrates

DOEpatents

Carey, Paul G.; Smith, Patrick M.; Sigmon, Thomas W.; Aceves, Randy C.

2004-01-20

A process for formation of thin film transistors (TFTs) on plastic substrates replaces standard thin film transistor fabrication techniques, and uses sufficiently lower processing temperatures so that inexpensive plastic substrates may be used in place of standard glass, quartz, and silicon wafer-based substrates. The silicon based thin film transistor produced by the process includes a low temperature substrate incapable of withstanding sustained processing temperatures greater than about 250.degree. C., an insulating layer on the substrate, a layer of silicon on the insulating layer having sections of doped silicon, undoped silicon, and poly-silicon, a gate dielectric layer on the layer of silicon, a layer of gate metal on the dielectric layer, a layer of oxide on sections of the layer of silicon and the layer of gate metal, and metal contacts on sections of the layer of silicon and layer of gate metal defining source, gate, and drain contacts, and interconnects.

Selenium extraction: development on extraction chromatographic resins compatible with Diffusive Gradient in Thin film (DGT)

NASA Astrophysics Data System (ADS)

Rad, S.; Dirks-Fandrei, C.; Happel, S. A.; Bombard, A.; Cary, L.

2016-12-01

Measurement of Selenium is of importance regarding public health as the ratio between beneficial daily intake and toxicity is rather low [1], [2]. Also from the radiological perspective, Se-79 as a long-lived fission nuclide (T1/2=2.8x105y) with high mobility in environment, is of concern regarding waste management and decommissioning [3], [4]. Due to the existence of different oxidation states Selenium has a complex speciation chemistry which makes extraction and separation schemes not straightforward. The aim of this research is to develop extraction methods for Selenium based on extraction chromatographic resins allowing for the extraction of Se(VI), as well as Se(IV), from water samples for later use on DGT (Diffusive Gradients in Thin films) devices. Extraction chromatographic resins have been tested and characterized for Se and other elements. For Se(VI) a commercially available Aliquat 336 based extraction chromatographic resin (TEVA resin[5]) was found to be most suitable, for Se(IV) a newly developed extraction chromatographic resin based on Piazselenol chemistry was found to be most effective, data on the selectivity of this resin will be presented. The extraction of Se(IV) and Se(VI) by these resins was tested on water sampled in Lille City, where a high Se spatial variability has been observed. Concentrations in groundwater can reach 30µg/L as a consequence; most Se-contaminated wells are no longer exploited by the water operators. One of the applications of this development is to be able to measure Se concentrations insitu in contaminated areas including very complex object such as hyporheic zone. [1] Cary L. et al. Applied Geochemistry 48 (2014) 70-82 [2] Chen C. et al. Biological Trace Element Research Vols. 71-72 (1999) 131-138 [3] http://www.irsn.fr/FR/Larecherche/publications-documentation/fiches-radionucleides/Documents/environnement/Selenium_Se79_v2.pdf last access 03/03/2016 [4] Uchida et al. WM2009 Conference, March 1-5, 2009, Phoenix, AZ [5] Horwitz P. et al. Analytica Chimica Acta 310 (1995) 63-78

Room temperature rubbing for few-layer two-dimensional thin flakes directly on flexible polymer substrates

PubMed Central

Yu, Yan; Jiang, Shenglin; Zhou, Wenli; Miao, Xiangshui; Zeng, Yike; Zhang, Guangzu; Liu, Sisi

2013-01-01

The functional layers of few-layer two-dimensional (2-D) thin flakes on flexible polymers for stretchable applications have attracted much interest. However, most fabrication methods are “indirect” processes that require transfer steps. Moreover, previously reported “transfer-free” methods are only suitable for graphene and not for other few-layer 2-D thin flakes. Here, a friction based room temperature rubbing method is proposed for fabricating different types of few-layer 2-D thin flakes (graphene, hexagonal boron nitride (h-BN), molybdenum disulphide (MoS2), and tungsten disulphide (WS2)) on flexible polymer substrates. Commercial 2-D raw materials (graphite, h-BN, MoS2, and WS2) that contain thousands of atom layers were used. After several minutes, different types of few-layer 2-D thin flakes were fabricated directly on the flexible polymer substrates by rubbing procedures at room temperature and without any transfer step. These few-layer 2-D thin flakes strongly adhere to the flexible polymer substrates. This strong adhesion is beneficial for future applications. PMID:24045289

Polymer thin film as coating layer to prevent corrosion of metal/metal oxide film

NASA Astrophysics Data System (ADS)

Sarkar, Suman; Kundu, Sarathi

2018-04-01

Thin film of polymer is used as coating layer and the corrosion of metal/metal oxide layer is studied with the variation of the thickness of the coating layer. The thin layer of polystyrene is fabricated using spin coating method on copper oxide (CuO) film which is deposited on glass substrate using DC magnetron sputtering technique. Thickness of the polystyrene and the CuO layers are determined using X-ray reflectivity (XRR) technique. CuO thin films coated with the polystyrene layer are exposed to acetic acid (2.5 v/v% aqueous CH3COOH solution) environments and are subsequently analyzed using UV-Vis spectroscopy and atomic force microscopy (AFM). Surface morphology of the film before and after interaction with the acidic environment is determined using AFM. Results obtained from the XRR and UV-Vis spectroscopy confirm that the thin film of polystyrene acts as an anticorrosion coating layer and the strength of the coating depends upon the polymer layer thickness at a constant acid concentration.

Nonenzymatic detection of glucose using BaCuO2 thin layer

NASA Astrophysics Data System (ADS)

Ito, Takeshi; Asada, Tsuyoshi; Asai, Naoto; Shimizu, Tomohiro; Shingubara, Shoso

2017-01-01

A BaCuO2 thin layer was deposited on a glassy carbon electrode and used for the direct oxidation of glucose. The crystalline, electrochemical, and physicochemical properties that depend on the deposition temperature and deposition time were studied. X-ray diffraction (XRD) analysis showed that the thin layer was amorphous even at 400 °C. The current density of the glucose oxidation using the thin layer deposited at 200 °C was higher than those at other deposition temperatures. Under this condition, the current density increased with the glucose concentration and deposition time. These results indicate that a BaCuO2 thin layer has potential for measuring the blood glucose level without enzymes.

Methods for making thin layers of crystalline materials

DOEpatents

Lagally, Max G; Paskiewicz, Deborah M; Tanto, Boy

2013-07-23

Methods for making growth templates for the epitaxial growth of compound semiconductors and other materials are provided. The growth templates are thin layers of single-crystalline materials that are themselves grown epitaxially on a substrate that includes a thin layer of sacrificial material. The thin layer of sacrificial material, which creates a coherent strain in the single-crystalline material as it is grown thereon, includes one or more suspended sections and one or more supported sections.

Atomic Force Microscope Mediated Chromatography

NASA Technical Reports Server (NTRS)

Anderson, Mark S.

2013-01-01

The atomic force microscope (AFM) is used to inject a sample, provide shear-driven liquid flow over a functionalized substrate, and detect separated components. This is demonstrated using lipophilic dyes and normal phase chromatography. A significant reduction in both size and separation time scales is achieved with a 25-micron-length column scale, and one-second separation times. The approach has general applications to trace chemical and microfluidic analysis. The AFM is now a common tool for ultra-microscopy and nanotechnology. It has also been demonstrated to provide a number of microfluidic functions necessary for miniaturized chromatography. These include injection of sub-femtoliter samples, fluidic switching, and sheardriven pumping. The AFM probe tip can be used to selectively remove surface layers for subsequent microchemical analysis using infrared and tip-enhanced Raman spectroscopy. With its ability to image individual atoms, the AFM is a remarkably sensitive detector that can be used to detect separated components. These diverse functional components of microfluidic manipulation have been combined in this work to demonstrate AFM mediated chromatography. AFM mediated chromatography uses channel-less, shear-driven pumping. This is demonstrated with a thin, aluminum oxide substrate and a non-polar solvent system to separate a mixture of lipophilic dyes. In conventional chromatographic terms, this is analogous to thin-layer chromatography using normal phase alumina substrate with sheardriven pumping provided by the AFM tip-cantilever mechanism. The AFM detection of separated components is accomplished by exploiting the variation in the localized friction of the separated components. The AFM tip-cantilever provides the mechanism for producing shear-induced flows and rapid pumping. Shear-driven chromatography (SDC) is a relatively new concept that overcomes the speed and miniaturization limitations of conventional liquid chromatography. SDC is based on a sliding plate system, consisting of two flat surfaces, one of which has a recessed channel. A fluid flow is produced by axially sliding one plate past another, where the fluid has mechanical shear forces imposed at each point along the channel length. The shear-induced flow rates are very reproducible, and do not have pressure or voltage gradient limitations. SDC opens up a new range of enhanced separation kinetics by permitting the sample confinement with submicron dimensions. Small, highly confined liquid is advantageous for chromatographic separation because the separation rate is known to scale according to the square of the confined sample diameter. In addition, because shear-driven flows are not limited by fluid velocity, shear-driven liquid chromatography may provide up to 100,000 plate efficiency.

Improvement in temperature dependence and dielectric tunability properties of PbZr0.52Ti0.48O3 thin films using Ba(Mg1/3Ta2/3)O3 buffer layer

NASA Astrophysics Data System (ADS)

Wu, Zhi; Zhou, Jing; Chen, Wen; Shen, Jie; Yang, Huimin; Zhang, Shisai; Liu, Yueli

2016-12-01

In this paper, Pb(Zr0.52Ti0.48)O3 (PZT) thin films were prepared via sol-gel method. The effects of Ba(Mg1/3Ta2/3)O3 (BMT) buffer layer on the temperature dependence and dielectric tunability properties of PZT thin films were studied. As the thickness of BMT buffer layer increases, the tan δ and tunability of PZT thin films decrease while tunability still maintains above 10%. This result shows that BMT buffer layer can improve the dielectric tunability properties of PZT thin films. Furthermore, the temperature coefficient of the dielectric constant decreases from 2333.4 to 906.9 ppm/°C with the thickness of BMT buffer layer increasing in the range from 25 to 205 °C, indicating that BMT buffer layer can improve the temperature stability of PZT thin films. Therefore, BMT buffer layer plays a critical role in improving temperature dependence and dielectric tunability properties of PbZr0.52Ti0.48O3 thin films.

Breakthrough to Non-Vacuum Deposition of Single-Crystal, Ultra-Thin, Homogeneous Nanoparticle Layers: A Better Alternative to Chemical Bath Deposition and Atomic Layer Deposition

PubMed Central

Liao, Yu-Kuang; Liu, Yung-Tsung; Hsieh, Dan-Hua; Shen, Tien-Lin; Hsieh, Ming-Yang; Tzou, An-Jye; Chen, Shih-Chen; Tsai, Yu-Lin; Lin, Wei-Sheng; Chan, Sheng-Wen; Shen, Yen-Ping; Cheng, Shun-Jen; Chen, Chyong-Hua; Wu, Kaung-Hsiung; Chen, Hao-Ming; Kuo, Shou-Yi; Charlton, Martin D. B.; Hsieh, Tung-Po; Kuo, Hao-Chung

2017-01-01

Most thin-film techniques require a multiple vacuum process, and cannot produce high-coverage continuous thin films with the thickness of a few nanometers on rough surfaces. We present a new ”paradigm shift” non-vacuum process to deposit high-quality, ultra-thin, single-crystal layers of coalesced sulfide nanoparticles (NPs) with controllable thickness down to a few nanometers, based on thermal decomposition. This provides high-coverage, homogeneous thickness, and large-area deposition over a rough surface, with little material loss or liquid chemical waste, and deposition rates of 10 nm/min. This technique can potentially replace conventional thin-film deposition methods, such as atomic layer deposition (ALD) and chemical bath deposition (CBD) as used by the Cu(In,Ga)Se2 (CIGS) thin-film solar cell industry for decades. We demonstrate 32% improvement of CIGS thin-film solar cell efficiency in comparison to reference devices prepared by conventional CBD deposition method by depositing the ZnS NPs buffer layer using the new process. The new ZnS NPs layer allows reduction of an intrinsic ZnO layer, which can lead to severe shunt leakage in case of a CBD buffer layer. This leads to a 65% relative efficiency increase. PMID:28383488

Layer-by-Layer Assembly of a pH-Responsive and Electrochromic Thin Film

ERIC Educational Resources Information Center

Schmidt, Daniel J.; Pridgen, Eric M.; Hammond, Paula T.; Love, J. Christopher

2010-01-01

This article summarizes an experiment on thin-film fabrication with layer-by-layer assembly that is appropriate for undergraduate laboratory courses. The purpose of this experiment is to teach students about self-assembly in the context of thin films and to expose students to the concepts of functional polymeric coatings. Students dip coat…

Gyrotactic trapping: A numerical study

NASA Astrophysics Data System (ADS)

Ghorai, S.

2016-04-01

Gyrotactic trapping is a mechanism proposed by Durham et al. ["Disruption of vertical motility by shear triggers formation of thin Phytoplankton layers," Science 323, 1067-1070 (2009)] to explain the formation of thin phytoplankton layer just below the ocean surface. This mechanism is examined numerically using a rational model based on the generalized Taylor dispersion theory. The crucial role of sedimentation speed in the thin layer formation is demonstrated. The effects of variation in different parameters on the thin layer formation are also investigated.

Thin-film metal coated insulation barrier in a Josephson tunnel junction. [Patent application

DOEpatents

Hawkins, G.A.; Clarke, J.

1975-10-31

A highly stable, durable, and reproducible Josephson tunnel junction consists of a thin-film electrode of a hard superconductor, a thin oxide insulation layer over the electrode constituting a Josephson tunnel junction barrier, a thin-film layer of stabilizing metal over the barrier, and a second thin-film hard superconductive electrode over the stabilizing film. The thin stabilizing metal film is made only thick enough to limit penetration of the electrode material through the insulation layer so as to prevent a superconductive short.

Fabrication of Crack-Free Barium Titanate Thin Film with High Dielectric Constant Using Sub-Micrometric Scale Layer-by-Layer E-Jet Deposition.

PubMed

Liang, Junsheng; Li, Pengfei; Wang, Dazhi; Fang, Xu; Ding, Jiahong; Wu, Junxiong; Tang, Chang

2016-01-19

Dense and crack-free barium titanate (BaTiO₃, BTO) thin films with a thickness of less than 4 μm were prepared by using sub-micrometric scale, layer-by-layer electrohydrodynamic jet (E-jet) deposition of the suspension ink which is composed of BTO nanopowder and BTO sol. Impacts of the jet height and line-to-line pitch of the deposition on the micro-structure of BTO thin films were investigated. Results show that crack-free BTO thin films can be prepared with 4 mm jet height and 300 μm line-to-line pitch in this work. Dielectric constant of the prepared BTO thin film was recorded as high as 2940 at 1 kHz at room temperature. Meanwhile, low dissipation factor of the BTO thin film of about 8.6% at 1 kHz was also obtained. The layer-by-layer E-jet deposition technique developed in this work has been proved to be a cost-effective, flexible and easy to control approach for the preparation of high-quality solid thin film.

Performance enhancement in Sb doped Cu(InGa)Se2 thin film solar cell by e-beam evaporation

NASA Astrophysics Data System (ADS)

Chen, Jieyi; Shen, Honglie; Zhai, Zihao; Li, Yufang; Yi, Yunge

2018-03-01

To investigate the effects of Sb doping on the structural and electrical properties of Cu(InGa)Se2 (CIGS) thin films and solar cells, CIGS thin films, prepared by e-beam evaporation on soda-lime glass, were doped with lower and upper Sb layers in the precursor stacks respectively. Change of structure and introduction of stress were observed in the CIGS thin films with upper Sb layer in stack through XRD and Raman measurement. Both crystalline quality and compactness of CIGS thin films were improved by the doping of upper Sb layer in stack and the CIGS thin film showed an optimal structural property with 20 nm Sb layer. Movement of Fermi level of the surface of CIGS thin film after doping of upper Sb layer in stack and electrons transfer between Cu/Cu+ redox couple and CIGS thin films, which provided probability for the substitution of Sb for Cu sites at the surface of CIGS thin films, were proposed to explain the migration of Cu from the surface to the bulk of CIGS thin films. The larger barrier at the CIGS/CdS interface after doping of upper Sb layer in stack made contribution to the increase of VOC of CIGS solar cells. The efficiency of CIGS solar cell was improved from 3.3% to 7.2% after doping with 20 nm upper Sb. Compared to the CIGS solar cell with lower Sb layer in stack, in which an additional Cu2-xSe phase was found, the CIGS solar cell with upper Sb layer in stack possessed a higher efficiency.

Evaluation of double-layer density modulated Si thin films as Li-ion battery anodes

NASA Astrophysics Data System (ADS)

Taha Demirkan, Muhammed; Yurukcu, Mesut; Dursun, Burcu; Demir-Cakan, Rezan; Karabacak, Tansel

2017-10-01

Double-layer density modulated silicon thin films which contain alternating low and high density Si film layers were fabricated by magnetron sputtering. Two different samples consisting of alternating layers of high-density/low-density and low-density/high-density Si thin film layers were investigated as anode electrodes in Li-ion batteries. Si thin film in which the terminating layer at the top is low density Si layer-quoted as low-density/high-density film (LD/HD)- exhibits better performance than Si thin film that has high density layer at the top, -quoted as high-density/low-density (HD/LD). A highly stabilized cycling performance with the specific charge capacities of 2000 mAh g-1 at the 150th cycle at C/2 current density, and 1200 mAh g-1 at the 240th cycle at 10 C current density were observed for the LD/HD Si anode in the presence of fluoroethylene carbonate (FEC) electrolyte additive.

Photovoltaic devices comprising cadmium stannate transparent conducting films and method for making

DOEpatents

Wu, Xuanzhi; Coutts, Timothy J.; Sheldon, Peter; Rose, Douglas H.

1999-01-01

A photovoltaic device having a substrate, a layer of Cd.sub.2 SnO.sub.4 disposed on said substrate as a front contact, a thin film comprising two or more layers of semiconductor materials disposed on said layer of Cd.sub.2 SnO.sub.4, and an electrically conductive film disposed on said thin film of semiconductor materials to form a rear electrical contact to said thin film. The device is formed by RF sputter coating a Cd.sub.2 SnO.sub.4 layer onto a substrate, depositing a thin film of semiconductor materials onto the layer of Cd.sub.2 SnO.sub.4, and depositing an electrically conductive film onto the thin film of semiconductor materials.

Amplitude various angles (AVA) phenomena in thin layer reservoir: Case study of various reservoirs

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nurhandoko, Bagus Endar B., E-mail: bagusnur@bdg.centrin.net.id, E-mail: bagusnur@rock-fluid.com; Rock Fluid Imaging Lab., Bandung; Susilowati, E-mail: bagusnur@bdg.centrin.net.id, E-mail: bagusnur@rock-fluid.com

2015-04-16

Amplitude various offset is widely used in petroleum exploration as well as in petroleum development field. Generally, phenomenon of amplitude in various angles assumes reservoir’s layer is quite thick. It also means that the wave is assumed as a very high frequency. But, in natural condition, the seismic wave is band limited and has quite low frequency. Therefore, topic about amplitude various angles in thin layer reservoir as well as low frequency assumption is important to be considered. Thin layer reservoir means the thickness of reservoir is about or less than quarter of wavelength. In this paper, I studied aboutmore » the reflection phenomena in elastic wave which considering interference from thin layer reservoir and transmission wave. I applied Zoeppritz equation for modeling reflected wave of top reservoir, reflected wave of bottom reservoir, and also transmission elastic wave of reservoir. Results show that the phenomena of AVA in thin layer reservoir are frequency dependent. Thin layer reservoir causes interference between reflected wave of top reservoir and reflected wave of bottom reservoir. These phenomena are frequently neglected, however, in real practices. Even though, the impact of inattention in interference phenomena caused by thin layer in AVA may cause inaccurate reservoir characterization. The relation between classes of AVA reservoir and reservoir’s character are different when effect of ones in thin reservoir and ones in thick reservoir are compared. In this paper, I present some AVA phenomena including its cross plot in various thin reservoir types based on some rock physics data of Indonesia.« less

Uncooled thin film pyroelectric IR detector with aerogel thermal isolation

DOEpatents

Ruffner, Judith A.; Bullington, Jeff A.; Clem, Paul G.; Warren, William L.; Brinker, C. Jeffrey; Tuttle, Bruce A.; Schwartz, Robert W.

1999-01-01

A monolithic infrared detector structure which allows integration of pyroelectric thin films atop low thermal conductivity aerogel thin films. The structure comprises, from bottom to top, a substrate, an aerogel insulating layer, a lower electrode, a pyroelectric layer, and an upper electrode layer capped by a blacking layer. The aerogel can offer thermal conductivity less than that of air, while providing a much stronger monolithic alternative to cantilevered or suspended air-gap structures for pyroelectric thin film pixel arrays. Pb(Zr.sub.0.4 Ti.sub.0.6)O.sub.3 thin films deposited on these structures displayed viable pyroelectric properties, while processed at 550.degree. C.

Microstructure and thermochromic properties of VOX-WOX-VOX ceramic thin films

NASA Astrophysics Data System (ADS)

Khamseh, S.; Araghi, H.; Ghahari, M.; Faghihi Sani, M. A.

2016-03-01

W-doped VO2 films have been synthesized via oxygen annealing of V-W-V (vanadium-tungsten-vanadium) multilayered films. The effects of middle layer's thickness of V-W-V multilayered film on structure and properties of VOX-WOX-VOX ceramic thin films were investigated. The as-deposited V-W-V multilayered film showed amorphous-like structure when mixed structure of VO2 (M) and VO2 (B) was formed in VOX-WOX-VOX ceramic thin films. Tungsten content of VOX-WOX-VOX ceramic thin films increased with increasing middle layer's thickness. With increasing middle layer's thickness, room temperature square resistance ( R sq) of VOX-WOX-VOX ceramic thin films increased from 65 to 86 kΩ/sq. The VOX-WOX-VOX ceramic thin film with the thinnest middle layer showed significant SMT (semiconductor-metal transition) when SMT became negligible on increasing middle layer's thickness.

System and Method for Fabricating Super Conducting Circuitry on Both Sides of an Ultra-Thin Layer

NASA Technical Reports Server (NTRS)

Brown, Ari D. (Inventor); Mikula, Vilem (Inventor)

2017-01-01

A method of fabricating circuitry in a wafer includes depositing a superconducting metal on a silicon on insulator wafer having a handle wafer, coating the wafer with a sacrificial layer and bonding the wafer to a thermally oxide silicon wafer with a first epoxy. The method includes flipping the wafer, thinning the flipped wafer by removing a handle wafer, etching a buried oxide layer, depositing a superconducting layer, bonding the wafer to a thermally oxidized silicon wafer having a handle wafer using an epoxy, flipping the wafer again, thinning the flipped wafer, etching a buried oxide layer from the wafer and etching the sacrificial layer from the wafer. The result is a wafer having superconductive circuitry on both sides of an ultra-thin silicon layer.

Photoluminescence-based quality control for thin film absorber layers of photovoltaic devices

DOEpatents

Repins, Ingrid L.; Kuciauskas, Darius

2015-07-07

A time-resolved photoluminescence-based system providing quality control during manufacture of thin film absorber layers for photovoltaic devices. The system includes a laser generating excitation beams and an optical fiber with an end used both for directing each excitation beam onto a thin film absorber layer and for collecting photoluminescence from the absorber layer. The system includes a processor determining a quality control parameter such as minority carrier lifetime of the thin film absorber layer based on the collected photoluminescence. In some implementations, the laser is a low power, pulsed diode laser having photon energy at least great enough to excite electron hole pairs in the thin film absorber layer. The scattered light may be filterable from the collected photoluminescence, and the system may include a dichroic beam splitter and a filter that transmit the photoluminescence and remove scattered laser light prior to delivery to a photodetector and a digital oscilloscope.

Device and method for luminescence enhancement by resonant energy transfer from an absorptive thin film

DOE Office of Scientific and Technical Information (OSTI.GOV)

Akselrod, Gleb M.; Bawendi, Moungi G.; Bulovic, Vladimir

Disclosed are a device and a method for the design and fabrication of the device for enhancing the brightness of luminescent molecules, nanostructures, and thin films. The device includes a mirror, a dielectric medium or spacer, an absorptive layer, and a luminescent layer. The absorptive layer is a continuous thin film of a strongly absorbing organic or inorganic material. The luminescent layer may be a continuous luminescent thin film or an arrangement of isolated luminescent species, e.g., organic or metal-organic dye molecules, semiconductor quantum dots, or other semiconductor nanostructures, supported on top of the absorptive layer.

Advanced germanium layer transfer for ultra thin body on insulator structure

NASA Astrophysics Data System (ADS)

Maeda, Tatsuro; Chang, Wen-Hsin; Irisawa, Toshifumi; Ishii, Hiroyuki; Hattori, Hiroyuki; Poborchii, Vladimir; Kurashima, Yuuichi; Takagi, Hideki; Uchida, Noriyuki

2016-12-01

We present the HEtero-Layer Lift-Off (HELLO) technique to obtain ultra thin body (UTB) Ge on insulator (GeOI) substrates. The transferred ultra thin Ge layers are characterized by the Raman spectroscopy measurements down to the thickness of ˜1 nm, observing a strong Raman intensity enhancement for high quality GeOI structure in ultra thin regime due to quantum size effect. This advanced Ge layer transfer technique enabled us to demonstrate UTB-GeOI nMOSFETs with the body thickness of only 4 nm.

Y1Ba2Cu3O(6+delta) growth on thin Y-enhanced SiO2 buffer layers on silicon

NASA Technical Reports Server (NTRS)

Robin, T.; Mesarwi, A.; Wu, N. J.; Fan, W. C.; Espoir, L.; Ignatiev, A.; Sega, R.

1991-01-01

SiO2 buffer layers as thin as 2 nm have been developed for use in the growth of Y1Ba2Cu3O(6+delta) thin films on silicon substrates. The SiO2 layers are formed through Y enhancement of silicon oxidation, and are highly stoichiometric. Y1Ba2Cu3O(6+delta) film growth on silicon with thin buffer layers has shown c orientation and Tc0 = 78 K.

Photovoltaic devices comprising cadmium stannate transparent conducting films and method for making

DOEpatents

Wu, X.; Coutts, T.J.; Sheldon, P.; Rose, D.H.

1999-07-13

A photovoltaic device is disclosed having a substrate, a layer of Cd[sub 2]SnO[sub 4] disposed on said substrate as a front contact, a thin film comprising two or more layers of semiconductor materials disposed on said layer of Cd[sub 2]SnO[sub 4], and an electrically conductive film disposed on said thin film of semiconductor materials to form a rear electrical contact to said thin film. The device is formed by RF sputter coating a Cd[sub 2]SnO[sub 4] layer onto a substrate, depositing a thin film of semiconductor materials onto the layer of Cd[sub 2]SnO[sub 4], and depositing an electrically conductive film onto the thin film of semiconductor materials. 10 figs.

Chromatographic analysis of toxic phosphylated oximes (POX): a brief overview.

PubMed

Becker, Christian; Worek, Franz; John, Harald

2010-10-01

Poisoning with organophosphorus compounds (OP), e.g. pesticides and nerve agents, causes inhibition of acetylcholinesterase (AChE) by phosphylation of the active site serine residue. Consequently, accumulation of stimulating acetylcholine in the synaptic cleft induces cholinergic crisis which ultimately may lead to death. For standard causal therapy, enzyme reactivators are administered representing oxime derivatives of quarternary pyridinium compounds, e.g. pralidoxime (2-PAM), obidoxime and HI 6. The mechanism of action includes removal of the phosphyl moiety by a nucleophilic attack of the oximate molecule substituting the enzyme and forming a phosphylated oxime (POX). POX is produced in stoichiometric amounts of reactivated enzyme and exhibits a significantly enhanced toxicity (inhibition rate constant) when compared to the parent OP. However, stability of POX under physiological conditions appears to be highly limited. Nevertheless, the presence of POX reveals a potential critical issue for both therapeutic efficacy in vivo and pharmacokinetic and pharmacodynamic (PK-PD) modelling based on cholinesterase activity data. Detailed characterization represents an important need for elaboration of the entire oxime pharmacology.Nevertheless, reports on POX toxicity and analysis are quite rare and may therefore be indicative of the challenge of POX analysis. This review provides a concise overview of chromatographic approaches applied to POX separation. Chromatography represents the key technology for POX purification and quantification in kinetic in vitro studies using buffers and biological fluids. Applications based on reversed-phase chromatography (RPC), ion pair chromatography (IPC) and an affinity approach as well as thin layer chromatography (TLC) are discussed and novel applications and data are presented. Copyright © 2010 John Wiley & Sons, Ltd.

Layered Organization in the Coastal Ocean: 4-D Assessment of Thin Layer Structure, Dynamics and Impacts

DTIC Science & Technology

2009-09-30

maintenance and dissipation of layers; (2) to understand the spatial coherence and spatial properties of thin layers in the coastal ocean (especially in...ORCAS profilers at K1 South and K2 had a Nortek ADV (Acoustic Doppler Velocity meter) for simultaneously measuring centimeter- scale currents and...year will be used to (1) detect the presence, intensity, thickness, temporal persistence, and spatial coherence of thin optical and acoustical layers

A tri-layer thin film containing graphene oxide to protect zinc substrates from wear

NASA Astrophysics Data System (ADS)

Wang, Ying; Gu, Zhengpeng; Yuan, Ningyi; Chu, Fuqiang; Cheng, Guanggui; Ding, Jianning

2018-06-01

Due to its excellent properties, Zn alloy is widely used in daily life. However, the poor wear-resisting properties of Zn alloys limits their application. In this paper, a tri-layer thin film consisting of 3-aminopropyltriethoxysilane (APS), graphene oxide (GO) and perfluoropolyethers (PFPE) were successfully prepared on the surface of Zn alloy to improve the wear-resisting properties. The as-prepared tri-layer thin films were characterized by atomic force microscopy, Raman spectroscopy, x-ray photoelectron spectroscopy and contact angle measurement. In addition, the tribological properties of the as-prepared tri-layer thin films were studied on a ball-on-plate tribometer and the morphologies of worn surfaces were observed using 3D noncontact interferometric microscope. Compared with the control samples, the tri-layer thin films showed excellent friction-reducing and wear-resisting properties, which was attributed to the synergistic effect of the GO as the load-carrying layer and the PFPE as the lubricating layer.

Fabrication of Crack-Free Barium Titanate Thin Film with High Dielectric Constant Using Sub-Micrometric Scale Layer-by-Layer E-Jet Deposition

PubMed Central

Liang, Junsheng; Li, Pengfei; Wang, Dazhi; Fang, Xu; Ding, Jiahong; Wu, Junxiong; Tang, Chang

2016-01-01

Dense and crack-free barium titanate (BaTiO3, BTO) thin films with a thickness of less than 4 μm were prepared by using sub-micrometric scale, layer-by-layer electrohydrodynamic jet (E-jet) deposition of the suspension ink which is composed of BTO nanopowder and BTO sol. Impacts of the jet height and line-to-line pitch of the deposition on the micro-structure of BTO thin films were investigated. Results show that crack-free BTO thin films can be prepared with 4 mm jet height and 300 μm line-to-line pitch in this work. Dielectric constant of the prepared BTO thin film was recorded as high as 2940 at 1 kHz at room temperature. Meanwhile, low dissipation factor of the BTO thin film of about 8.6% at 1 kHz was also obtained. The layer-by-layer E-jet deposition technique developed in this work has been proved to be a cost-effective, flexible and easy to control approach for the preparation of high-quality solid thin film. PMID:28787860

MultiLayer solid electrolyte for lithium thin film batteries

DOEpatents

Lee, Se -Hee; Tracy, C. Edwin; Pitts, John Roland; Liu, Ping

2015-07-28

A lithium metal thin-film battery composite structure is provided that includes a combination of a thin, stable, solid electrolyte layer [18] such as Lipon, designed in use to be in contact with a lithium metal anode layer; and a rapid-deposit solid electrolyte layer [16] such as LiAlF.sub.4 in contact with the thin, stable, solid electrolyte layer [18]. Batteries made up of or containing these structures are more efficient to produce than other lithium metal batteries that use only a single solid electrolyte. They are also more resistant to stress and strain than batteries made using layers of only the stable, solid electrolyte materials. Furthermore, lithium anode batteries as disclosed herein are useful as rechargeable batteries.

Developments of the Physical and Electrical Properties of NiCr and NiCrSi Single-Layer and Bi-Layer Nano-Scale Thin-Film Resistors.

PubMed

Cheng, Huan-Yi; Chen, Ying-Chung; Li, Chi-Lun; Li, Pei-Jou; Houng, Mau-Phon; Yang, Cheng-Fu

2016-02-25

In this study, commercial-grade NiCr (80 wt % Ni, 20 wt % Cr) and NiCrSi (55 wt % Ni, 40 wt % Cr, 5 wt % Si) were used as targets and the sputtering method was used to deposit NiCr and NiCrSi thin films on Al₂O₃ and Si substrates at room temperature under different deposition time. X-ray diffraction patterns showed that the NiCr and NiCrSi thin films were amorphous phase, and the field-effect scanning electronic microscope observations showed that only nano-crystalline grains were revealed on the surfaces of the NiCr and NiCrSi thin films. The log (resistivity) values of the NiCr and NiCrSi thin-film resistors decreased approximately linearly as their thicknesses increased. We found that the value of temperature coefficient of resistance (TCR value) of the NiCr thin-film resistors was positive and that of the NiCrSi thin-film resistors was negative. To investigate these thin-film resistors with a low TCR value, we designed a novel bi-layer structure to fabricate the thin-film resistors via two different stacking methods. The bi-layer structures were created by depositing NiCr for 10 min as the upper (or lower) layer and depositing NiCrSi for 10, 30, or 60 min as the lower (or upper) layer. We aim to show that the stacking method had no apparent effect on the resistivity of the NiCr-NiCrSi bi-layer thin-film resistors but had large effect on the TCR value.

Developments of the Physical and Electrical Properties of NiCr and NiCrSi Single-Layer and Bi-Layer Nano-Scale Thin-Film Resistors

PubMed Central

Cheng, Huan-Yi; Chen, Ying-Chung; Li, Chi-Lun; Li, Pei-Jou; Houng, Mau-Phon; Yang, Cheng-Fu

2016-01-01

In this study, commercial-grade NiCr (80 wt % Ni, 20 wt % Cr) and NiCrSi (55 wt % Ni, 40 wt % Cr, 5 wt % Si) were used as targets and the sputtering method was used to deposit NiCr and NiCrSi thin films on Al2O3 and Si substrates at room temperature under different deposition time. X-ray diffraction patterns showed that the NiCr and NiCrSi thin films were amorphous phase, and the field-effect scanning electronic microscope observations showed that only nano-crystalline grains were revealed on the surfaces of the NiCr and NiCrSi thin films. The log (resistivity) values of the NiCr and NiCrSi thin-film resistors decreased approximately linearly as their thicknesses increased. We found that the value of temperature coefficient of resistance (TCR value) of the NiCr thin-film resistors was positive and that of the NiCrSi thin-film resistors was negative. To investigate these thin-film resistors with a low TCR value, we designed a novel bi-layer structure to fabricate the thin-film resistors via two different stacking methods. The bi-layer structures were created by depositing NiCr for 10 min as the upper (or lower) layer and depositing NiCrSi for 10, 30, or 60 min as the lower (or upper) layer. We aim to show that the stacking method had no apparent effect on the resistivity of the NiCr-NiCrSi bi-layer thin-film resistors but had large effect on the TCR value. PMID:28344296

Monitoring the layer-by-layer self-assembly of graphene and graphene oxide by spectroscopic ellipsometry.

PubMed

Zhou, Kai-Ge; Chang, Meng-Jie; Wang, Hang-Xing; Xie, Yu-Long; Zhang, Hao-Li

2012-01-01

Thin films of graphene oxide, graphene and copper (II) phthalocyanine dye have been successfully fabricated by electrostatic layer-by-layer (LbL) assembly approach. We present the first variable angle spectroscopic ellipsometry (VASE) investigation on these graphene-dye hybrid thin films. The thickness evaluation suggested that our LbL assembly process produces highly uniform and reproducible thin films. We demonstrate that the refractive indices of the graphene-dye thin films undergo dramatic variation in the range close to the absorption of the dyes. This investigation provides new insight to the optical properties of graphene containing thin films and shall help to establish an appropriate optical model for graphene-based hybrid materials.

Influences of Indium Tin Oxide Layer on the Properties of RF Magnetron-Sputtered (BaSr)TiO3 Thin Films on Indium Tin Oxide-Coated Glass Substrate

NASA Astrophysics Data System (ADS)

Kim, Tae Song; Oh, Myung Hwan; Kim, Chong Hee

1993-06-01

Nearly stoichiometric ((Ba+Sr)/Ti=1.08-1.09) and optically transparent (BaSr)TiO3 thin films were deposited on an indium tin oxide (ITO)-coated glass substrate by means of rf magnetron sputtering for their application to the insulating layer of an electroluminescent flat panel display. The influence of the ITO layer on the properties of (BaSr)TiO3 thin films deposited on the ITO-coated substrate was investigated. The ITO layer did not affect the crystallographic orientation of (BaSr)TiO3 thin film, but enhanced the grain growth. Another effect of the ITO layer on (BaSr)TiO3 thin films was the interdiffusion phenomenon, which was studied by means of secondary ion mass spectrometry (SIMS). As the substrate temperature increased, interdiffusion intensified at the interface not only between the grown film and ITO layer but also between the ITO layer and base glass substrate. The refractive index (nf) of (BaSr)TiO3 thin film deposited on a bare glass substrate was 2.138-2.286, as a function of substrate temperature.

Corrosion-resistant multilayer structures with improved reflectivity

DOEpatents

Soufli, Regina; Fernandez-Perea, Monica; Robinson, Jeff C.

2013-04-09

In one general embodiment, a thin film structure includes a substrate; a first corrosion barrier layer above the substrate; a reflective layer above the first corrosion barrier layer, wherein the reflective layer comprises at least one repeating set of sub-layers, wherein one of the sub-layers of each set of sub-layers being of a corrodible material; and a second corrosion barrier layer above the reflective layer. In another general embodiment, a system includes an optical element having a thin film structure as recited above; and an image capture or spectrometer device. In a further general embodiment, a laser according to one embodiment includes a light source and the thin film structure as recited above.

Internal hypersonic flow. [in thin shock layer

NASA Technical Reports Server (NTRS)

Lin, T. C.; Rubin, S. G.

1974-01-01

An approach for studying hypersonic internal flow with the aid of a thin-shock-layer approximation is discussed, giving attention to a comparison of thin-shock-layer results with the data obtained on the basis of the imposition theory or a finite-difference integration of the Euler equations. Relations in the case of strong interaction are considered together with questions of pressure distribution and aspects of the boundary-layer solution.

Methods for producing thin film charge selective transport layers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hammond, Scott Ryan; Olson, Dana C.; van Hest, Marinus Franciscus Antonius Maria

Methods for producing thin film charge selective transport layers are provided. In one embodiment, a method for forming a thin film charge selective transport layer comprises: providing a precursor solution comprising a metal containing reactive precursor material dissolved into a complexing solvent; depositing the precursor solution onto a surface of a substrate to form a film; and forming a charge selective transport layer on the substrate by annealing the film.

Al-/Ga-Doped ZnO Window Layers for Highly Efficient Cu₂ZnSn(S,Se)₄ Thin Film Solar Cells.

PubMed

Seo, Se Won; Seo, Jung Woo; Kim, Donghwan; Cheon, Ki-Beom; Lee, Doh-Kwon; Kim, Jin Young

2018-09-01

The successful use of Al-/Ga-doped ZnO (AGZO) thin films as a transparent conducting oxide (TCO) layer of a Cu2ZnSn(S,Se)4 (CZTSSe) thin film solar cell is demonstrated. The AGZO thin films were prepared by radio frequency (RF) sputtering. The structural, crystallographic, electrical, and optical properties of the AGZO thin films were systematically investigated. The photovoltaic properties of CZTSSe thin film solar cells incorporating the AGZO-based TCO layer were also reported. It has been found that the RF power and substrate temperature of the AGZO thin film are important factors determining the electrical, optical, and structural properties. The optimization process involving the RF power and the substrate temperature leads to good electrical and optical transmittance of the AGZO thin films. Finally, the CZTSSe solar cell with the AGZO TCO layer demonstrated a high conversion efficiency of 9.68%, which is higher than that of the conventional AZO counterpart by 12%.

Growth and optical property characterization of textured barium titanate thin films for photonic applications

NASA Astrophysics Data System (ADS)

Dicken, Matthew J.; Diest, Kenneth; Park, Young-Bae; Atwater, Harry A.

2007-03-01

We have investigated the growth of barium titanate thin films on bulk crystalline and amorphous substrates utilizing biaxially oriented template layers. Ion beam-assisted deposition was used to grow thin, biaxially textured, magnesium oxide template layers on amorphous and silicon substrates. Growth of highly oriented barium titanate films on these template layers was achieved by molecular beam epitaxy using a layer-by-layer growth process. Barium titanate thin films were grown in molecular oxygen and in the presence of oxygen radicals produced by a 300 W radio frequency plasma. We used X-ray and in situ reflection high-energy electron diffraction (RHEED) to analyze the structural properties and show the predominantly c-oriented grains in the films. Variable angle spectroscopic ellipsometry was used to analyze and compare the optical properties of the thin films grown with and without oxygen plasma. We have shown that optical quality barium titanate thin films, which show bulk crystal-like properties, can be grown on any substrate through the use of biaxially oriented magnesium oxide template layers.

Effect of different coating layer on the topography and optical properties of ZnO nanostructured

NASA Astrophysics Data System (ADS)

Mohamed, R.; Mamat, M. H.; Malek, M. F.; Ismail, A. S.; Yusoff, M. M.; Asiah, M. N.; Khusaimi, Z.; Rusop, M.

2018-05-01

Magnesium (Mg) and aluminum (Al) co-doped zinc oxide (MAZO) thin films were synthesized on glass substrate by sol-gel spin coating method. MAZO thin films were prepared at different coating layers range from 1 to 9. Atomic Force Microscopy (AFM) was used to investigate the topography of the thin films. According to the AFM results, Root Means Square (RMS) of MAZO thin films was increased from 0.747 to 6.545 nm, with increase of number coating layer from 1 to 9, respectively. The results shown the variation on structural and topography properties of MAZO seed film when it's deposited at different coating layers on glass substrate. The optical properties was analyzed using UV-Vis spectroscopy. The obtained results show that the transmittance spectra was increased as thin films coating layer increases.

Thin layer model for nonlinear evolution of the Rayleigh-Taylor instability

NASA Astrophysics Data System (ADS)

Zhao, K. G.; Wang, L. F.; Xue, C.; Ye, W. H.; Wu, J. F.; Ding, Y. K.; Zhang, W. Y.

2018-03-01

On the basis of the thin layer approximation [Ott, Phys. Rev. Lett. 29, 1429 (1972)], a revised thin layer model for incompressible Rayleigh-Taylor instability has been developed to describe the deformation and nonlinear evolution of the perturbed interface. The differential equations for motion are obtained by analyzing the forces (the gravity and pressure difference) of fluid elements (i.e., Newton's second law). The positions of the perturbed interface are obtained from the numerical solution of the motion equations. For the case of vacuum on both sides of the layer, the positions of the upper and lower interfaces obtained from the revised thin layer approximation agree with that from the weakly nonlinear (WN) model of a finite-thickness fluid layer [Wang et al., Phys. Plasmas 21, 122710 (2014)]. For the case considering the fluids on both sides of the layer, the bubble-spike amplitude from the revised thin layer model agrees with that from the WN model [Wang et al., Phys. Plasmas 17, 052305 (2010)] and the expanded Layzer's theory [Goncharov, Phys. Rev. Lett. 88, 134502 (2002)] in the early nonlinear growth regime. Note that the revised thin layer model can be applied to investigate the perturbation growth at arbitrary Atwood numbers. In addition, the large deformation (the large perturbed amplitude and the arbitrary perturbed distributions) in the initial stage can also be described by the present model.

Two-dimensional models for the optical response of thin films

NASA Astrophysics Data System (ADS)

Li, Yilei; Heinz, Tony F.

2018-04-01

In this work, we present a systematic study of 2D optical models for the response of thin layers of material under excitation by normally incident light. The treatment, within the framework of classical optics, analyzes a thin film supported by a semi-infinite substrate, with both the thin layer and the substrate assumed to exhibit local, isotropic linear response. Starting from the conventional three-dimensional (3D) slab model of the system, we derive a two-dimensional (2D) sheet model for the thin film in which the optical response is described by a sheet optical conductivity. We develop criteria for the applicability of this 2D sheet model for a layer with an optical thickness far smaller than the wavelength of the light. We examine in detail atomically thin semi-metallic and semiconductor van-der-Waals layers and ultrathin metal films as representative examples. Excellent agreement of the 2D sheet model with the 3D slab model is demonstrated over a broad spectral range from the radio frequency limit to the near ultraviolet. A linearized version of system response for the 2D model is also presented for the case where the influence of the optically thin layer is sufficiently weak. Analytical expressions for the applicability and accuracy of the different optical models are derived, and the appropriateness of the linearized treatment for the materials is considered. We discuss the advantages, as well as limitations, of these models for the purpose of deducing the optical response function of the thin layer from experiment. We generalize the theory to take into account in-plane anisotropy, layered thin film structures, and more general substrates. Implications of the 2D model for the transmission of light by the thin film and for the implementation of half- and totally absorbing layers are discussed.

Initial formation of calcite crystals in the thin prismatic layer with the periostracum of Pinctada fucata.

PubMed

Suzuki, Michio; Nakayama, Seiji; Nagasawa, Hiromichi; Kogure, Toshihiro

2013-02-01

Although the formation mechanism of calcite crystals in the prismatic layer has been studied well in many previous works, the initial state of calcite formation has not been observed in detail using electron microscopes. In this study, we report that the soft prismatic layer with transparent color (the thin prismatic layer) in the tip of the fresh shell of Pinctada fucata was picked up to observe the early calcification phase. A scanning electron microscope (SEM) image showed that the growth tip of the thin prismatic layer was covered by the periostracum, which was also where the initial formation of calcite crystals began. A cross-section containing the thin calcite crystals in the thin prismatic layer with the periostracum was made using a focused ion beam (FIB) system. In a transmission electron microscope (TEM) observation, the thin calcite crystal (thickness is about 1μm) on the periostracum was found to be a single crystal with the c-axis oriented perpendicular to the shell surface. On the other hand, many aggregated small particles consisting of bassanite crystals were observed in the periostracum suggesting the possibility that not only organic sulfate but also inorganic sulfates exist in the prismatic layer. These discoveries in the early calcification phase of the thin prismatic layer may help to clarify the mechanism of regulating the nucleation and orientation of the calcite crystal in the shell. Copyright © 2012 Elsevier Ltd. All rights reserved.

Buffer layers for high-Tc thin films on sapphire

NASA Technical Reports Server (NTRS)

Wu, X. D.; Foltyn, S. R.; Muenchausen, R. E.; Cooke, D. W.; Pique, A.; Kalokitis, D.; Pendrick, V.; Belohoubek, E.

1992-01-01

Buffer layers of various oxides including CeO2 and yttrium-stabilized zirconia (YSZ) have been deposited on R-plane sapphire. The orientation and crystallinity of the layers were optimized to promote epitaxial growth of YBa2Cu3O(7-delta) (YBCO) thin films. An ion beam channeling minimum yield of about 3 percent was obtained in the CeO2 layer on sapphire, indicating excellent crystallinity of the buffer layer. Among the buffer materials used, CeO2 was found to be the best one for YBCO thin films on R-plane sapphire. High Tc and Jc were obtained in YBCO thin films on sapphire with buffer layers. Surface resistances of the YBCO films were about 4 mOmega at 77 K and 25 GHz.

Layered ultra-thin coherent structures used as electrical resistors having low-temperature coefficient of resistivity

DOEpatents

Werner, T.R.; Falco, C.M.; Schuller, I.K.

1982-08-31

A thin film resistor having a controlled temperature coefficient of resistance (TCR) ranging from negative to positive degrees kelvin and having relatively high resistivity. The resistor is a multilayer superlattice crystal containing a plurality of alternating, ultra-thin layers of two different metals. TCR is varied by controlling the thickness of the individual layers. The resistor can be readily prepared by methods compatible with thin film circuitry manufacturing techniques.

Effect of ZnO buffer layer on phase transition properties of vanadium dioxide thin films

NASA Astrophysics Data System (ADS)

Zhu, Huiqun; Li, Lekang; Li, Chunbo

2016-03-01

VO2 thin films were prepared on ZnO buffer layers by DC magnetron sputtering at room temperature using vanadium target and post annealing at 400 °C. The ZnO buffer layers with different thickness deposited on glass substrates by magnetron sputtering have a high visible and near infrared optical transmittance. The electrical resistivity and the phase transition properties of the VO2/ZnO composite thin films in terms of temperature were investigated. The results showed that the resistivity variation of VO2 thin film with ZnO buffer layer deposited for 35 min was 16 KΩ-cm. The VO2/ZnO composite thin films exhibit a reversible semiconductor-metal phase transition at 48 °C.

Thin-Layer Fuel Cell for Teaching and Classroom Demonstrations

ERIC Educational Resources Information Center

Shirkhanzadeh, M.

2009-01-01

A thin-layer fuel cell is described that is simple and easy to set up and is particularly useful for teaching and classroom demonstrations. The cell is both an electrolyzer and a fuel cell and operates using a thin layer of electrolyte with a thickness of approximately 127 micrometers and a volume of approximately 40 microliters. As an…

Optical characterizations of silver nanoprisms embedded in polymer thin film layers

NASA Astrophysics Data System (ADS)

Carlberg, Miriam; Pourcin, Florent; Margeat, Olivier; Le Rouzo, Judikael; Berginc, Gerard; Sauvage, Rose-Marie; Ackermann, Jorg; Escoubas, Ludovic

2017-10-01

The precise control of light-matter interaction has a wide range of applications and is currently driven by the use of nanoparticles (NPs) by the recent advances in nanotechnology. Taking advantage of the material, size, shape, and surrounding media dependence of the optical properties of plasmonic NPs, thin film layers with tunable optical properties are achieved. The NPs are synthesized by wet chemistry and embedded in a polyvinylpyrrolidone (PVP) polymer thin film layer. Spectrophotometer and spectroscopic ellipsometry measurements are coupled to finite-difference time domain numerical modeling to optically characterize the heterogeneous thin film layers. Silver nanoprisms of 10 to 50 nm edge size exhibit high absorption through the visible wavelength range. A simple optical model composed of a Cauchy law and a Lorentz law, accounting for the optical properties of the nonabsorbing polymer and the absorbing property of the nanoprisms, fits the spectroscopic ellipsometry measurements. Knowing the complex optical indices of heterogeneous thin film layers let us design layers of any optical properties.

Extracting elastic properties of an atomically thin interfacial layer by time-domain analysis of femtosecond acoustics

NASA Astrophysics Data System (ADS)

Chen, H.-Y.; Huang, Y.-R.; Shih, H.-Y.; Chen, M.-J.; Sheu, J.-K.; Sun, C.-K.

2017-11-01

Modern devices adopting denser designs and complex 3D structures have created much more interfaces than before, where atomically thin interfacial layers could form. However, fundamental information such as the elastic property of the interfacial layers is hard to measure. The elastic property of the interfacial layer is of great importance in both thermal management and nano-engineering of modern devices. Appropriate techniques to probe the elastic properties of interfacial layers as thin as only several atoms are thus critically needed. In this work, we demonstrated the feasibility of utilizing the time-resolved femtosecond acoustics technique to extract the elastic properties and mass density of a 1.85-nm-thick interfacial layer, with the aid of transmission electron microscopy. We believe that this femtosecond acoustics approach will provide a strategy to measure the absolute elastic properties of atomically thin interfacial layers.

Determination of the Mass Absorption Coefficient in Two-Layer Ti/V and V/Ti Thin Film Systems by the X-Ray Fluorescence Method

NASA Astrophysics Data System (ADS)

Mashin, N. I.; Chernyaeva, E. A.; Tumanova, A. N.; Gafarova, L. M.

2016-03-01

A new XRF procedure for the determination of the mass absorption coefficient in thin film Ti/V and V/Ti two-layer systems has been proposed. The procedure uses easy-to-make thin-film layers of sputtered titanium and vanadium on a polymer film substrate. Correction coefficients have been calculated that take into account attenuation of primary radiation of the X-ray tube, as well as attenuation of the spectral line of the bottom layer element in the top layer.

High Performance and Highly Reliable ZnO Thin Film Transistor Fabricated by Atomic Layer Deposition for Next Generation Displays

DTIC Science & Technology

2011-08-19

zinc oxide ( ZnO ) thin film as an active channel layer in TFT has become of great interest owing to their specific...630-0192 Japan Phone: +81-743-72-6060 Fax: +81-743-72-6069 E-mail: uraoka@ms.naist.jp Keywords: zinc oxide , thin film transistors , atomic layer...deposition Symposium topic: Transparent Semiconductors Oxides [Abstract] In this study, we fabricated TFTs using ZnO thin film as the

Domain matched epitaxial growth of (111) Ba{sub 0.5}Sr{sub 0.5}TiO{sub 3} thin films on (0001) Al{sub 2}O{sub 3} with ZnO buffer layer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Krishnaprasad, P. S., E-mail: pskrishnaprasu@gmail.com, E-mail: mkj@cusat.ac.in; Jayaraj, M. K., E-mail: pskrishnaprasu@gmail.com, E-mail: mkj@cusat.ac.in; Antony, Aldrin

2015-03-28

Epitaxial (111) Ba{sub 0.5}Sr{sub 0.5}TiO{sub 3} (BST) thin films have been grown by pulsed laser deposition on (0001) Al{sub 2}O{sub 3} substrate with ZnO as buffer layer. The x-ray ω-2θ, Φ-scan and reciprocal space mapping indicate epitaxial nature of BST thin films. The domain matched epitaxial growth of BST thin films over ZnO buffer layer was confirmed using Fourier filtered high resolution transmission electron microscope images of the film-buffer interface. The incorporation of ZnO buffer layer effectively suppressed the lattice mismatch and promoted domain matched epitaxial growth of BST thin films. Coplanar inter digital capacitors fabricated on epitaxial (111) BSTmore » thin films show significantly improved tunable performance over polycrystalline thin films.« less

Experimental Study of Acid Treatment Toward Characterization of Structural, Optical, and Morphological Properties of TiO2-SnO2 Composite Thin Film

NASA Astrophysics Data System (ADS)

Fajar, M. N.; Hidayat, R.; Triwikantoro; Endarko

2018-04-01

The TiO2-SnO2 thin film with single and double-layer structure has successfully synthesized on FTO (Fluorine-doped Tin Oxide) substrate using the screen printing technique. The structural, optical, and morphological properties of the film were investigated by XRD, UV-Vis, and SEM, respectively. The results showed that the single and double-layer structure of TiO2-SnO2 thin film has mixed phase with a strong formation of casseritte phase. The acid treatment effect on TiO2-SnO2 thin film decreases the peak intensity of anatase phase formation and thin film’s absorbance values. The morphological study is also revealed that the single layer TiO2-SnO2 thin film had a more porous nature and decreased particle size distribution after acid treatment, while the double-layer TiO2-SnO2 thin film Eroded due to acid treatment.

Nanopore thin film enabled optical platform for drug loading and release.

PubMed

Song, Chao; Che, Xiangchen; Que, Long

2017-08-07

In this paper, a drug loading and release device fabricated using nanopore thin film and layer-by-layer (LbL) nanoassembly is reported. The nanopore thin film is a layer of anodic aluminum oxide (AAO), consisting of honeycomb-shape nanopores. Using the LbL nanoassembly process, the drug, using gentamicin sulfate (GS) as the model, can be loaded into the nanopores and the stacked layers on the nanopore thin film surface. The drug release from the device is achieved by immersing it into flowing DI water. Both the loading and release processes can be monitored optically. The effect of the nanopore size/volume on drug loading and release has also been evaluated. Further, the neuron cells have been cultured and can grow normally on the nanopore thin film, verifying its bio-compatibility. The successful fabrication of nanopore thin film device on silicon membrane render it as a potential implantable controlled drug release device.

Surface passivation investigation on ultra-thin atomic layer deposited aluminum oxide layers for their potential application to form tunnel layer passivated contacts

NASA Astrophysics Data System (ADS)

Xin, Zheng; Ling, Zhi Peng; Nandakumar, Naomi; Kaur, Gurleen; Ke, Cangming; Liao, Baochen; Aberle, Armin G.; Stangl, Rolf

2017-08-01

The surface passivation performance of atomic layer deposited ultra-thin aluminium oxide layers with different thickness in the tunnel layer regime, i.e., ranging from one atomic cycle (∼0.13 nm) to 11 atomic cycles (∼1.5 nm) on n-type silicon wafers is studied. The effect of thickness and thermal activation on passivation performance is investigated with corona-voltage metrology to measure the interface defect density D it(E) and the total interface charge Q tot. Furthermore, the bonding configuration variation of the AlO x films under various post-deposition thermal activation conditions is analyzed by Fourier transform infrared spectroscopy. Additionally, poly(3,4-ethylenedioxythiophene) poly(styrene sulfonate) is used as capping layer on ultra-thin AlO x tunneling layers to further reduce the surface recombination current density to values as low as 42 fA/cm2. This work is a useful reference for using ultra-thin ALD AlO x layers as tunnel layers in order to form hole selective passivated contacts for silicon solar cells.

Wound Healing Potential of Formulated Extract from Hibiscus Sabdariffa Calyx

PubMed Central

Builders, P. F.; Kabele-Toge, B.; Builders, M.; Chindo, B. A.; Anwunobi, Patricia A.; Isimi, Yetunde C.

2013-01-01

Wound healing agents support the natural healing process, reduce trauma and likelihood of secondary infections and hasten wound closure. The wound healing activities of water in oil cream of the methanol extract of Hibiscus sabdariffa L. (Malvaceae) was evaluated in rats with superficial skin excision wounds. Antibacterial activities against Pseudomonas aeroginosa, Staphylococcus aureus and Echerichia coli were determined. The total flavonoid content, antioxidant properties and thin layer chromatographic fingerprints of the extract were also evaluated. The extract demonstrated antioxidant properties with a total flavonoid content of 12.30±0.09 mg/g. Six reproducible spots were obtained using methanol:water (95:5) as the mobile phase. The extract showed no antimicrobial activity on the selected microorganisms, which are known to infect and retard wound healing. Creams containing H. sabdariffa extract showed significant (P<0.05) and concentration dependent wound healing activities. There was also evidence of synergism with creams containing a combination of gentamicin and H. sabdariffa extract. This study, thus, provides evidence of the wound healing potentials of the formulated extract of the calyces of H. sabdariffa and synergism when co-formulated with gentamicin. PMID:23901160

The characterization of ficaprenol-10, -11 and -12 from the leaves of Ficus elastica (decorative rubber plant)

PubMed Central

Stone, K. J.; Wellburn, A. R.; Hemming, F. W.; Pennock, J. F.

1967-01-01

Evidence from mass, nuclear-magnetic-resonance and infrared spectrometry and from gas–liquid and thin-layer chromatography is presented in favour of the presence of cis–trans-decaprenol, -undecaprenol and -dodecaprenol in the mixture of polyprenols (2·6mg./g.) isolated from leaf tissue of Ficus elastica. The trivial names ficaprenol-10, -11 and -12 are proposed. Nuclear-magnetic-resonance studies showed that each of these prenols contains three trans internal isoprene residues and a cis `OH-terminal' isoprene residue. Ficaprenol-11 is the major component of the mixture. Chromatographic evidence suggests the presence also of small amounts of ficaprenol-9 and -13. The precise position of the three trans internal isoprene residues was not determined but it is suggested that these are adjacent to the ω-terminal isoprene residue and that the ficaprenols are formed from all-trans-geranylgeranyl pyrophosphate. It is also suggested that ficaprenol-10, -11, -12 and -13 are probably the same compounds as castaprenol-10, -11, -12 and -13. PMID:6030292

Thin-layer chromatography with stationary phase gradient as a method for separation of water-soluble vitamins.

PubMed

Cimpoiu, Claudia; Hosu, Anamaria; Puscas, Anitta

2012-02-03

The group of hydrophilic vitamins play an important role in human health, and their lack or excess produces specific diseases. Therefore, the analysis of these compounds is indispensable for monitoring their content in pharmaceuticals and food in order to prevent some human diseases. TLC was successfully applied in the analysis of hydrophilic vitamins, but the most difficult problem in the simultaneous analysis of all these compounds is to find an optimum stationary phase-mobile phase system due to different chemical characteristics of analytes. Unfortunately structural analogues are difficult to separate in one chromatographic run, and this is the case in hydrophilic vitamins investigations. TLC gives the possibility to perform two-dimensional separations by using stationary phase gradient achieving the highest resolution by combining two systems with different selectivity. The goal of this work was to develop a method of analysis enabling separation of hydrophilic vitamins using TLC with adsorbent gradient. The developed method was used for identifying the water-soluble vitamins in alcoholic extracts of Hippophae rhamnoides and of Ribes nigrum. Copyright © 2011 Elsevier B.V. All rights reserved.

Ceftriaxone-associated gallbladder sludge. Identification of calcium-ceftriaxone salt as a major component of gallbladder precipitate

DOE Office of Scientific and Technical Information (OSTI.GOV)

Park, H.Z.; Lee, S.P.; Schy, A.L.

1991-06-01

Ceftriaxone, a third-generation cephalosporin, is partially excreted into bile. With its clinical use, the formation of gallbladder sludge detected by ultrasonography has been reported. Four surgical specimens were examined and no gallstones were found. Instead, fine precipitates of 20-250 microns were present. Microscopically, there was a small number of cholesterol monohydrate crystals and bilirubin granules among an abundant amount of granular-crystalline material that was not morphologically cholesterol monohydrate crystals. The chemical composition of the precipitates (n = 4) was determined. There was a small amount of cholesterol (1.7% +/- 0.8%) and bilirubin (13.9% +/- 0.74%). The major component of themore » precipitate was a residue. On further analysis using thin-layer chromatography, high-performance liquid chromatography, and electron microprobe analysis, the residue was identified as a calcium salt of ceftriaxone. The residue also had identical crystal morphology and chromatographic elution profile as authentic calcium-ceftriaxone standards. It is concluded that ceftriaxone, after excretion and being concentrated in the gallbladder bile, can form a precipitate. The major constituent has been identified as a ceftriaxone-calcium salt.« less

An image analysis of TLC patterns for quality control of saffron based on soil salinity effect: A strategy for data (pre)-processing.

PubMed

Sereshti, Hassan; Poursorkh, Zahra; Aliakbarzadeh, Ghazaleh; Zarre, Shahin; Ataolahi, Sahar

2018-01-15

Quality of saffron, a valuable food additive, could considerably affect the consumers' health. In this work, a novel preprocessing strategy for image analysis of saffron thin layer chromatographic (TLC) patterns was introduced. This includes performing a series of image pre-processing techniques on TLC images such as compression, inversion, elimination of general baseline (using asymmetric least squares (AsLS)), removing spots shift and concavity (by correlation optimization warping (COW)), and finally conversion to RGB chromatograms. Subsequently, an unsupervised multivariate data analysis including principal component analysis (PCA) and k-means clustering was utilized to investigate the soil salinity effect, as a cultivation parameter, on saffron TLC patterns. This method was used as a rapid and simple technique to obtain the chemical fingerprints of saffron TLC images. Finally, the separated TLC spots were chemically identified using high-performance liquid chromatography-diode array detection (HPLC-DAD). Accordingly, the saffron quality from different areas of Iran was evaluated and classified. Copyright © 2017 Elsevier Ltd. All rights reserved.

Stability studies on diloxanide furoate: effect of pH, temperature, gastric and intestinal fluids.

PubMed

Gadkariem, E A; Belal, F; Abounassif, M A; El-Obeid, H A; E E Ibrahim, K

2004-04-01

The degradation of the amoebicide diloxanide furoate in alkaline medium at different temperatures was investigated using both a spectrophotometric and a developed HPLC method. In solutions, the drug was found to undergo decomposition, i.e., temperature and pH dependent. The pH-rate profile at pH between 7.6 and 9.6 indicated a first-order dependence of Kobs on [-OH]. Arrhenius plot obtained at pH 8 was linear between 40 and 63 degrees C. The estimated activation energy of hydrolysis was found to be 18.25 kcal degree.mol(-1). The effect of simulated gastric and intestinal fluids on the drug was also investigated. A new thin-layer chromatographic (TLC) procedure for the fractionation of the drug and its alkaline hydrolysis products has been developed and was found to compare favorably with that of the British Pharmacopoeia. Three hydrolysis products of a basic methanolic solution of the drug, namely furoic acid, diloxanide and methylfuroate could be identified by the use of TLC, HPLC, infrared and mass spectrometry.

Estimation of L-dopa from Mucuna pruriens LINN and formulations containing M. pruriens by HPTLC method.

PubMed

Modi, Ketan Pravinbhai; Patel, Natvarlal Manilal; Goyal, Ramesh Kishorilal

2008-03-01

A selective, precise, and accurate high-performance thin-layer chromatographic (HPTLC) method has been developed for the analysis of L-dopa in Mucuna pruriens seed extract and its formulations. The method involves densitometric evaluation of L-dopa after resolving it by HPTLC on silica gel plates with n-butanol-acetic acid-water (4.0+1.0+1.0, v/v) as the mobile phase. Densitometric analysis of L-dopa was carried out in the absorbance mode at 280 nm. The relationship between the concentration of L-dopa and corresponding peak areas was found to be linear in the range of 100 to 1200 ng/spot. The method was validated for precision (inter and intraday), repeatability, and accuracy. Mean recovery was 100.30%. The relative standard deviation (RSD) values of the precision were found to be in the range 0.64-1.52%. In conclusion, the proposed TLC method was found to be precise, specific and accurate and can be used for identification and quantitative determination of L-dopa in herbal extract and its formulations.

Indentification of huperzine A-producing endophytic fungi isolated from Huperzia serrata.

PubMed

Dong, Li-Hui; Fan, San-Wei; Ling, Qing-Zhi; Huang, Bei-Bei; Wei, Zhao-Jun

2014-03-01

This present study was designed to investigate the production of huperzine A (HupA), an acetylcholine inhibitor, which was produced by an endophytic fungi isolated from Huperzia serrata. Screening of 94 endophytic fungal isolates obtained from plant H. serrata was carried out for the production of HupA. Their morphological characteristics were studied and rDNA sequence analysis was carried out. The cultures were grown in liquid culture medium and the extracted metabolites were analyzed by thin layer chromatography and high performance liquid chromatograph for the presence of HupA. The DPPH scavenging ratio and inhibition ratio of acetylcholinesterase (AchE) of the same were determined. 3 out of 94 strains i.e. S29, L44 and S94 showed significant AchE-inhibitory activity and antioxidant activity. Strain L44 which exhibited maximum yield of HupA (37.63 μg/g on dry weight basis) was identified as Trichoderma species by ITS sequence analysis. In conclusion, endophytic fungi from H. serrata can be used as a new resource of HupA.

Femtogram detection of explosive nitroaromatics: fluoranthene-based fluorescent chemosensors.

PubMed

Venkatramaiah, N; Kumar, Shiv; Patil, Satish

2012-11-12

Herein we report a novel fluoranthene-based fluorescent fluorophore 7,10-bis(4-bromophenyl)-8,9-bis[4-(hexyloxy)phenyl]fluoranthene (S(3)) and its remarkable properties in applications of explosive detection. The sensitivity towards the detection of nitroaromatics (NACs) was evaluated through fluorescence quenching in solution, vapor, and contact mode approaches. The contact mode approach using thin-layer silica chromatographic plates exhibited a femtogram (1.15 fg cm(-2)) detection limit for trinitrotoluene (TNT) and picric acid (PA), whereas the solution-phase quenching showed PA detection at the 2-20 ppb level. Fluorescence lifetime measurements revealed that the quenching is static in nature and the quenching process is fully reversible. Binding energies between model binding sites of the S(3) and analyte compounds reveal that analyte molecules enter into the cavity created by substituted phenyl rings of fluoranthene and are stabilized by strong intermolecular interactions with alkyl chains. It is anticipated that the sensor S(3) could be a promising material for the construction of portable optical devices for the detection of onsite explosive nitroaromatics. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A validated densitometric method for analysis of atorvastatin calcium and metoprolol tartarate as bulk drugs and in combined capsule dosage forms.

PubMed

Patole, Sm; Khodke, As; Potale, Lv; Damle, Mc

2011-01-01

A simple, accurate and precise high-performance thin-layer chromatographic method has been developed for the estimation of Atorvastatin Calcium and Metoprolol Tartarate simultaneously from a capsule dosage form. The method employed Silica gel 60F (254s)precoated plates as stationary phase and a mixture of Chloroform: Methanol: Glacial acetic acid (dil.) :: (9:1.5:0.2 ml %v/v) as mobile phase. Densitometric scanning was performed at 220 nm using Camag TLC scanner 3. The method was linear in the drug concentrations' range of 500 to 2500 ng/spot for Atorvastatin Calcium, also for Metoprolol Tartarate with correlation coefficient of 0.984 for Atorvastatin Calcium and 0.995 for Metoprolol Tartarate respectively. The retention factor for Atorvastatin Calcium was 0.45 ± 0.04 and for Metoprolol Tartarate was 0.25 ± 0.02. The method was validated as per ICH (International Conference on Harmonisation) Guidelines, proving its utility in estimation of Atorvastatin Calcium and Metoprolol Tartarate in combined dosage form.

The C. elegans PRMT-3 possesses a type III protein arginine methyltransferase activity.

PubMed

Takahashi, Yuta; Daitoku, Hiroaki; Yokoyama, Atsuko; Nakayama, Kimihiro; Kim, Jun-Dal; Fukamizu, Akiyoshi

2011-04-01

Protein arginine methylation is a common post-translational modification in eukaryotes that is catalyzed by a family of the protein arginine methyltransferases (PRMTs). PRMTs are classified into three types: type I and type II add asymmetrically and symmetrically dimethyl groups to arginine, respectively, while type III adds solely monomethyl group to arginine. However, although the enzymatic activity of type I and type II PRMTs have been reported, the substrate specificity and the methylation activity of type III PRMTs still remains unknown. Here, we report the characterization of Caenorhabditis elegans PRMT-2 and PRMT-3, both of which are highly homologous to human PRMT7. We find that these two PRMTs can bind to S-adenosyl methionine (SAM), but only PRMT-3 has methyltransferase activity for histone H2A depending on its SAM-binding domain. Importantly, thin-layer chromatographic analysis demonstrates that PRMT-3 catalyzes the formation of monomethylated, but not dimethylated arginine. Our study thus identifies the first type III PRMT in C. elegans and provides a means to elucidate the physiological significance of arginine monomethylation in multicellular organisms.

Fabrication and properties of ZnO/GaN heterostructure nanocolumnar thin film on Si (111) substrate

PubMed Central

2013-01-01

Zinc oxide thin films have been obtained on bare and GaN buffer layer decorated Si (111) substrates by pulsed laser deposition (PLD), respectively. GaN buffer layer was achieved by a two-step method. The structure, surface morphology, composition, and optical properties of these thin films were investigated by X-ray diffraction, field emission scanning electron microscopy, infrared absorption spectra, and photoluminiscence (PL) spectra, respectively. Scanning electron microscopy images indicate that the flower-like grains were presented on the surface of ZnO thin films grown on GaN/Si (111) substrate, while the ZnO thin films grown on Si (111) substrate show the morphology of inclination column. PL spectrum reveals that the ultraviolet emission efficiency of ZnO thin film on GaN buffer layer is high, and the defect emission of ZnO thin film derived from Zni and Vo is low. The results demonstrate that the existence of GaN buffer layer can greatly improve the ZnO thin film on the Si (111) substrate by PLD techniques. PMID:23448090

Fabrication and properties of ZnO/GaN heterostructure nanocolumnar thin film on Si (111) substrate.

PubMed

Wei, Xianqi; Zhao, Ranran; Shao, Minghui; Xu, Xijin; Huang, Jinzhao

2013-02-28

Zinc oxide thin films have been obtained on bare and GaN buffer layer decorated Si (111) substrates by pulsed laser deposition (PLD), respectively. GaN buffer layer was achieved by a two-step method. The structure, surface morphology, composition, and optical properties of these thin films were investigated by X-ray diffraction, field emission scanning electron microscopy, infrared absorption spectra, and photoluminiscence (PL) spectra, respectively. Scanning electron microscopy images indicate that the flower-like grains were presented on the surface of ZnO thin films grown on GaN/Si (111) substrate, while the ZnO thin films grown on Si (111) substrate show the morphology of inclination column. PL spectrum reveals that the ultraviolet emission efficiency of ZnO thin film on GaN buffer layer is high, and the defect emission of ZnO thin film derived from Zni and Vo is low. The results demonstrate that the existence of GaN buffer layer can greatly improve the ZnO thin film on the Si (111) substrate by PLD techniques.

Conductive layer for biaxially oriented semiconductor film growth

DOEpatents

Findikoglu, Alp T.; Matias, Vladimir

2007-10-30

A conductive layer for biaxially oriented semiconductor film growth and a thin film semiconductor structure such as, for example, a photodetector, a photovoltaic cell, or a light emitting diode (LED) that includes a crystallographically oriented semiconducting film disposed on the conductive layer. The thin film semiconductor structure includes: a substrate; a first electrode deposited on the substrate; and a semiconducting layer epitaxially deposited on the first electrode. The first electrode includes a template layer deposited on the substrate and a buffer layer epitaxially deposited on the template layer. The template layer includes a first metal nitride that is electrically conductive and has a rock salt crystal structure, and the buffer layer includes a second metal nitride that is electrically conductive. The semiconducting layer is epitaxially deposited on the buffer layer. A method of making such a thin film semiconductor structure is also described.

Unexpected structural and magnetic depth dependence of YIG thin films

NASA Astrophysics Data System (ADS)

Cooper, J. F. K.; Kinane, C. J.; Langridge, S.; Ali, M.; Hickey, B. J.; Niizeki, T.; Uchida, K.; Saitoh, E.; Ambaye, H.; Glavic, A.

2017-09-01

We report measurements on yttrium iron garnet (YIG) thin films grown on both gadolinium gallium garnet (GGG) and yttrium aluminum garnet (YAG) substrates, with and without thin Pt top layers. We provide three principal results: the observation of an interfacial region at the Pt/YIG interface, we place a limit on the induced magnetism of the Pt layer, and confirm the existence of an interfacial layer at the GGG/YIG interface. Polarized neutron reflectometry (PNR) was used to give depth dependence of both the structure and magnetism of these structures. We find that a thin film of YIG on GGG is best described by three distinct layers: an interfacial layer near the GGG, around 5 nm thick and nonmagnetic, a magnetic "bulk" phase, and a nonmagnetic and compositionally distinct thin layer near the surface. We theorize that the bottom layer, which is independent of the film thickness, is caused by Gd diffusion. The top layer is likely to be extremely important in inverse spin Hall effect measurements, and is most likely Y2O3 or very similar. Magnetic sensitivity in the PNR to any induced moment in the Pt is increased by the existence of the Y2O3 layer; any moment is found to be less than 0.02 μB/atom .

Methods for fabricating thin film III-V compound solar cell

DOEpatents

Pan, Noren; Hillier, Glen; Vu, Duy Phach; Tatavarti, Rao; Youtsey, Christopher; McCallum, David; Martin, Genevieve

2011-08-09

The present invention utilizes epitaxial lift-off in which a sacrificial layer is included in the epitaxial growth between the substrate and a thin film III-V compound solar cell. To provide support for the thin film III-V compound solar cell in absence of the substrate, a backing layer is applied to a surface of the thin film III-V compound solar cell before it is separated from the substrate. To separate the thin film III-V compound solar cell from the substrate, the sacrificial layer is removed as part of the epitaxial lift-off. Once the substrate is separated from the thin film III-V compound solar cell, the substrate may then be reused in the formation of another thin film III-V compound solar cell.

Schottky barrier solar cell

NASA Technical Reports Server (NTRS)

Stirn, R. J.; Yeh, Y. C. M. (Inventor)

1981-01-01

A method of fabricating a Schottky barrier solar cell is described. The cell consists of a thin substrate of low cost material with at least the top surface of the substrate being electrically conductive. A thin layer of heavily doped n-type polycrystalling germanium is deposited on the substrate after a passivation layer is deposited to prevent migration of impurities into the polycrystalline germanium. The polycrystalline germanium is recrystallized to increase the crystal sizes to serve as a base layer on which a thin layer of gallium arsenide is vapor-epitaxilly grown followed by a thermally-grown oxide layer. A metal layer is deposited on the oxide layer and a grid electrode is deposited to be in electrical contact with the top surface of the metal layer.

Laser readable thermoluminescent radiation dosimeters and methods for producing thereof

DOEpatents

Braunlich, Peter F.; Tetzlaff, Wolfgang

1989-01-01

Thin layer thermoluminescent radiation dosimeters for use in laser readable dosimetry systems, and methods of fabricating such thin layer dosimeters. The thin layer thermoluminescent radiation dosimeters include a thin substrate made from glass or other inorganic materials capable of withstanding high temperatures and high heating rates. A thin layer of a thermoluminescent phoshphor material is heat bonded to the substrate using an inorganic binder such as glass. The dosimeters can be mounted in frames and cases for ease in handling. Methods of the invention include mixing a suitable phosphor composition and binder, both being in particulate or granular form. The mixture is then deposited onto a substrate such as by using mask printing techniques. The dosimeters are thereafter heated to fuse and bond the binder and phosphor to the substrate.

PHARMACOGNOSTIC STANDARDIZATION OF THE LEAF OF MELALEUCA ALTERNIFOLIA (MAIDEN & BETCHE) CHEEL

PubMed Central

Shah, Gagan; Baghel, Uttam Singh

2017-01-01

Background: Melaleuca alternifolia (Myrtaceae) is a well-known, commonly used, tall shrub plant in Ayurvedic medicine. Traditionally, it is used for its antimicrobial potential to treat cutaneous infections. No attempts have been made regarding pharmacognostic investigation of the plant till date. So, the present study was aimed to establish standards with the help of different pharmacognostic parameters. Methods: Various pharmacognostic parameters (morphological, microscopic, physicochemical evaluations and preliminary phytochemical screening) were studied along with fluorescent and thin layer chromatographic analysis of the extract. Result: Morphologically Melaleuca alternifolia is a shrub having height of 7 m with layered and papery bark. Leaves have an arranged pattern, petiole is 1 mm in length; linear-acute with dimensions of 10-35 mm x 1 mm. Organoleptic features shows that leaves have characteristic odour and astringent taste. The transverse section of the leaf reveals the existence of epidermal layers, mesophyll tissues, vascular bundles and secretory cavities. The stomata are anomocytic and leaf constants such as stomatal number is 180-200-225, stomatal index is 3.8-4.4-5.9, vein islet number is 18.68 (average), veinlet termination number 20.3 (average) and palisade ratio is 5.5-6.4-6.9. The results of phytochemical screening showed the occurrence of different phytoconstituents (flavonoids, phenolic tannins, phytosterol and terpenoids). Conclusion: The present study evaluated various pharmacognostic parameters which will help in quality control (standardization) of Melaleuca alternifolia leaves in crude form, in herbal formulation and also aid in the preparation of an herbal monograph for the species. PMID:28480411

Layered Organization in the Coastal Ocean: 4-D Assessment of Thin Layer Structure, Dynamics and Impacts

DTIC Science & Technology

2007-09-30

For example, the differences seen between the waters off of the US Pacific Northwest and the California Bight are almost certainly a reflection of the...the Pacific Northwest were favorable for thin layer development during that study. This is even more evident in those cases where thin layers...approach during the 2005 and 2006 LOCO process study combined time series data from an array of our Ocean Response Coastal Analysis System ( ORCAS ) (Donaghay

High average power scaleable thin-disk laser

DOEpatents

Beach, Raymond J.; Honea, Eric C.; Bibeau, Camille; Payne, Stephen A.; Powell, Howard; Krupke, William F.; Sutton, Steven B.

2002-01-01

Using a thin disk laser gain element with an undoped cap layer enables the scaling of lasers to extremely high average output power values. Ordinarily, the power scaling of such thin disk lasers is limited by the deleterious effects of amplified spontaneous emission. By using an undoped cap layer diffusion bonded to the thin disk, the onset of amplified spontaneous emission does not occur as readily as if no cap layer is used, and much larger transverse thin disks can be effectively used as laser gain elements. This invention can be used as a high average power laser for material processing applications as well as for weapon and air defense applications.

The enhancement mechanism of thin plasma layer on antenna radiation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Chunsheng, E-mail: wangcs@hit.edu.cn; Jiang, Binhao; Li, Xueai

A model of plasma-antenna is carried out to study the radiation enhancement mechanism of antenna covered by thin plasma layer. The results show when the radiation intensity achieves maximum, a region of equal electric field is formed due to the reflection of electric field at the interface of plasma and air. The plasma layer acted as an extension of the antenna. Furthermore, the shape of plasma layer is changed to verify the effect of plasma boundary on antenna radiation. The study shows the effect of thin plasma layer on electromagnetic field and provides a type of plasma antenna.

Estimation of methacrylate monolith binding capacity from pressure drop data.

PubMed

Podgornik, Aleš; Smrekar, Vida; Krajnc, Peter; Strancar, Aleš

2013-01-11

Convective chromatographic media comprising of membranes and monoliths represent an important group of chromatographic supports due to their flow-unaffected chromatographic properties and consequently fast separation and purification even of large biological macromolecules. Consisting of a single piece of material, common characterization procedures based on analysis of a small sample assuming to be representative for the entire batch, cannot be applied. Because of that, non-invasive characterization methods are preferred. In this work pressure drop was investigated for an estimation of dynamic binding capacity (DBC) of proteins and plasmid DNA for monoliths with different pore sizes. It was demonstrated that methacrylate monolith surface area is reciprocally proportional to pore diameter and that pressure drop on monolith is reciprocally proportional to square pore size demonstrating that methacrylate monolith microstructure is preserved by changing pore size. Based on these facts mathematical formalism has been derived predicting that DBC is in linear correlation with the square root of pressure drop. This was experimentally confirmed for ion-exchange and hydrophobic interactions for proteins and plasmid DNA. Furthermore, pressure drop was also applied for an estimation of DBC in grafted layers of different thicknesses as estimated from the pressure drop data. It was demonstrated that the capacity is proportional to the estimated grafted layer thickness. Copyright © 2012 Elsevier B.V. All rights reserved.

Improving Fire Resistance of Cotton Fabric through Layer-by-Layer Assembled Graphene Multilayer Nanocoating

NASA Astrophysics Data System (ADS)

Jang, Wonjun; Chung, Il Jun; Kim, Junwoo; Seo, Seongmin; Park, Yong Tae; Choi, Kyungwho

2018-05-01

In this study, thin films containing poly(vinyl alcohol) (PVA) and graphene nanoplatelets (GNPs), stabilized with poly(4-styrene-sulfonic acid) (PSS), were assembled by a simple and cost-effective layer-by-layer (LbL) technique in order to introduce the anti-flammability to cotton. These antiflammable layers were characterized by using UV-vis spectrometry and quartz crystal microbalance as a function of the number of bilayers deposited. Scanning electron microscopy was used to visualize the morphology of the thin film coatings on the cotton fabric. The graphene-polymer thin films introduced anti-flammable properties through thermally stable carbonaceous layers at a high temperature. The thermal stability and flame retardant property of graphene-coated cotton was demonstrated by thermogravimetric analysis, cone calorimetry, and vertical flame test. The results indicate that LbL-assembled graphene-polymer thin films can be applied largely in the field of flame retardant.

Programmable Electrochemical Rectifier Based on a Thin-Layer Cell.

PubMed

Park, Seungjin; Park, Jun Hui; Hwang, Seongpil; Kwak, Juhyoun

2017-06-21

A programmable electrochemical rectifier based on thin-layer electrochemistry is described here. Both the rectification ratio and the response time of the device are programmable by controlling the gap distance of the thin-layer electrochemical cell, which is easily controlled using commercially available beads. One of the electrodes was modified using a ferrocene-terminated self-assembled monolayer to offer unidirectional charge transfers via soluble redox species. The thin-layer configuration provided enhanced mass transport, which was determined by the gap thickness. The device with the smallest gap thickness (∼4 μm) showed an unprecedented, high rectification ratio (up to 160) with a fast response time in a two-terminal configuration using conventional electronics.

The effects of layering in ferroelectric Si-doped HfO{sub 2} thin films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lomenzo, Patrick D.; Nishida, Toshikazu, E-mail: nishida@ufl.edu; Takmeel, Qanit

2014-08-18

Atomic layer deposited Si-doped HfO{sub 2} thin films approximately 10 nm thick are deposited with various Si-dopant concentrations and distributions. The ferroelectric behavior of the HfO{sub 2} thin films are shown to be dependent on both the Si mol. % and the distribution of Si-dopants. Metal-ferroelectric-insulator-semiconductor capacitors are shown to exhibit a tunable remanent polarization through the adjustment of the Si-dopant distribution at a constant Si concentration. Inhomogeneous layering of Si-dopants within the thin films effectively lowers the remanent polarization. A pinched hysteresis loop is observed for higher Si-dopant concentrations and found to be dependent on the Si layering distribution.

NMR of thin layers using a meanderline surface coil

DOEpatents

Cowgill, Donald F.

2001-01-01

A miniature meanderline sensor coil which extends the capabilities of nuclear magnetic resonance (NMR) to provide analysis of thin planar samples and surface layer geometries. The sensor coil allows standard NMR techniques to be used to examine thin planar (or curved) layers, extending NMRs utility to many problems of modern interest. This technique can be used to examine contact layers, non-destructively depth profile into films, or image multiple layers in a 3-dimensional sense. It lends itself to high resolution NMR techniques of magic angle spinning and thus can be used to examine the bonding and electronic structure in layered materials or to observe the chemistry associated with aging coatings. Coupling this sensor coil technology with an arrangement of small magnets will produce a penetrator probe for remote in-situ chemical analysis of groundwater or contaminant sediments. Alternatively, the sensor coil can be further miniaturized to provide sub-micron depth resolution within thin films or to orthoscopically examine living tissue. This thin-layer NMR technique using a stationary meanderline coil in a series-resonant circuit has been demonstrated and it has been determined that the flat meanderline geometry has about he same detection sensitivity as a solenoidal coil, but is specifically tailored to examine planar material layers, while avoiding signals from the bulk.

Effect of processing parameters on microstructure of MoS{sub 2} ultra-thin films synthesized by chemical vapor deposition method

DOE Office of Scientific and Technical Information (OSTI.GOV)

Song, Yang; You, Suping; Sun, Kewei

2015-06-15

MoS{sub 2} ultra-thin layers are synthesized using a chemical vapor deposition method based on the sulfurization of molybdenum trioxide (MoO{sub 3}). The ultra-thin layers are characterized by X-ray diffraction (XRD), photoluminescence (PL) spectroscopy and atomic force microscope (AFM). Based on our experimental results, all the processing parameters, such as the tilt angle of substrate, applied voltage, heating time and the weight of source materials have effect on the microstructures of the layers. In this paper, the effects of such processing parameters on the crystal structures and morphologies of the as-grown layers are studied. It is found that the film obtainedmore » with the tilt angle of 0.06° is more uniform. A larger applied voltage is preferred to the growth of MoS{sub 2} thin films at a certain heating time. In order to obtain the ultra-thin layers of MoS{sub 2}, the weight of 0.003 g of source materials is preferred. Under our optimal experimental conditions, the surface of the film is smooth and composed of many uniformly distributed and aggregated particles, and the ultra-thin MoS{sub 2} atomic layers (1∼10 layers) covers an area of more than 2 mm×2 mm.« less

The properties of plasma-enhanced atomic layer deposition (ALD) ZnO thin films and comparison with thermal ALD

NASA Astrophysics Data System (ADS)

Kim, Doyoung; Kang, Hyemin; Kim, Jae-Min; Kim, Hyungjun

2011-02-01

Zinc oxide (ZnO) thin films were prepared by plasma-enhanced atomic layer deposition (PE-ALD) using oxygen plasma as a reactant and the properties were compared with those of thermal atomic layer deposition (TH-ALD) ZnO thin films. While hexagonal wurzite phase with preferential (0 0 2) orientation was obtained for both cases, significant differences were observed in various aspects of film properties including resistivity values between these two techniques. Photoluminescence (PL) measurements have shown that high resistivity of PE-ALD ZnO thin films is due to the oxygen interstitials at low growth temperature of 200 °C, whose amount decreases with increasing growth temperature. Thin film transistors (TFT) using TH- and PE-ALD ZnO as an active layer were also fabricated and the device properties were evaluated comparatively.

Laser readable thermoluminescent radiation dosimeters and methods for producing thereof

DOEpatents

Braunlich, P.F.; Tetzlaff, W.

1989-04-25

Thin layer thermoluminescent radiation dosimeters for use in laser readable dosimetry systems, and methods of fabricating such thin layer dosimeters are disclosed. The thin layer thermoluminescent radiation dosimeters include a thin substrate made from glass or other inorganic materials capable of withstanding high temperatures and high heating rates. A thin layer of a thermoluminescent phosphor material is heat bonded to the substrate using an inorganic binder such as glass. The dosimeters can be mounted in frames and cases for ease in handling. Methods of the invention include mixing a suitable phosphor composition and binder, both being in particulate or granular form. The mixture is then deposited onto a substrate such as by using mask printing techniques. The dosimeters are thereafter heated to fuse and bond the binder and phosphor to the substrate. 34 figs.

Fermi level de-pinning of aluminium contacts to n-type germanium using thin atomic layer deposited layers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gajula, D. R., E-mail: dgajula01@qub.ac.uk; Baine, P.; Armstrong, B. M.

Fermi-level pinning of aluminium on n-type germanium (n-Ge) was reduced by insertion of a thin interfacial dielectric by atomic layer deposition. The barrier height for aluminium contacts on n-Ge was reduced from 0.7 eV to a value of 0.28 eV for a thin Al{sub 2}O{sub 3} interfacial layer (∼2.8 nm). For diodes with an Al{sub 2}O{sub 3} interfacial layer, the contact resistance started to increase for layer thicknesses above 2.8 nm. For diodes with a HfO{sub 2} interfacial layer, the barrier height was also reduced but the contact resistance increased dramatically for layer thicknesses above 1.5 nm.

Identification and Structure Elucidation of Forced Degradation Products of the Novel Propionic acid Derivative Loxoprofen: Development of Stability-Indicating Chromatographic Methods Validated as per ICH Guidelines.

PubMed

Eissa, Maya S; Abd El-Sattar, Osama I

2017-04-01

Loxoprofen sodium (LOX) is a recently developed novel propionic acid derivative. Owing to its instability under both hydrolytic and oxidative conditions, the development of simple, rapid and sensitive methods for its determination in the presence of its possible forced degradation products becomes essential. Two simple chromatographic methods, high-performance thin layer chromatography (HPTLC) and high-performance liquid chromatography (HPLC), were developed associated with ultraviolet (UV) detection. In HPTLC-densitometric method, the separation of LOX from its degradation products was achieved using silica gel F254 plates and toluene:acetone:acetic acid (1.8:1.0:0.1, v/v/v) as the developing system followed by densitometric scanning at 220 nm. In the HPLC-UV method, the separation was performed using isocratic elution system with acetonitrile: 0.15% triethylamine (pH 2.2) (50:50, v/v) on C18 analytical column. The flow rate was optimized at 1.0 mL·min-1 and UV detection was achieved at 220 nm. Validation was performed in accordance with the International Conference on Harmonization guidelines and the method was perfectly applied for determination of LOX in its pharmaceutical preparation. The results obtained were statistically compared to those obtained after application of the official HPLC method, where no significant difference was found incompliance with precision and accuracy. Identification and characterization of the possible hydrolytic degradation product under alkaline conditions and that produced during oxidative degradation using hydrogen peroxide were structurally elucidated using infrared and mass spectrometry analyses. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

HPTLC Fingerprint Analysis: A Quality Control for Authentication of Herbal Phytochemicals

NASA Astrophysics Data System (ADS)

Ram, Mauji; Abdin, M. Z.; Khan, M. A.; Jha, Prabhakar

Authentication and consistent quality are the basic requirement for Indian traditional medicine (TIM), Chinese traditional herbal medicine (TCHM), and their commercial products, regardless of the kind of research conducted to modernize the TIM and TCHM. The complexities of TIM and TCHM challenge the current official quality control mode, for which only a few biochemical markers were selected for identification and quantitative assay. Referring too many unknown factors existed in TIM and TCHM, it is impossible and unnecessary to pinpoint qualitatively and quantitatively every single component contained in the herbal drug. Chromatographic fingerprint is a rational option to meet the need for more effective and powerful quality assessment to TIM and TCHM. The optimized chromatographic fingerprint is not only an alternative analytical tool for authentication, but also an approach to express the various pattern of chemical ingredients distribution in the herbal drugs and preserve such "database" for further multifaced sustainable studies. Analytical separation techniques, for example, high-performance liquid chromatography (HPLC), gas chromatography (GC) and mass spectrometry (MS) were among the most popular methods of choice used for quality control of raw material and finished herbal product. Fingerprint analysis approach using high-performance thin-layer chromatography (HPTLC) has become the most potent tool for quality control of herbal medicines because of its simplicity and reliability. It can serve as a tool for identification, authentication, and quality control of herbal drugs. In this chapter, attempts are being made to expand the use of HPTLC and at the same time create interest among prospective researcher in herbal analysis. The developed method can be used as a quality control tool for rapid authentication from a wide variety of herbal samples. Some examples demonstrated the role of fingerprinting in quality control and assessment.

Technetium-99m-Labeled Sulfadiazine: a Targeting Radiopharmaceutical for Scintigraphic Imaging of Infectious Foci Due To Escherichia coli in Mouse and Rabbit Models.

PubMed

Ahmed, Muhammad Tauqeer; Naqvi, Syed Ali Raza; Rasheed, Rashid; Zahoor, Ameer Fawad; Usman, Muhammad; Hussain, Zaib

2017-09-01

Bacterial infection is one of the vital reasons of morbidity and mortality, especially in developing countries. It appears silently without bothering the geological borders and imposes a grave threat to humanity. Nuclear medicine technique has an important role in helping early diagnosis of deep-seated infections. The aim of this study was to develop a new radiopharmaceutical 99m Tc-labeling sulfadiazine as an infection imaging agent. Radiolabeling of sulfadiazine with technetium-99m ( 99m Tc) was carried out using stannous tartrate as a reducing agent in the presence of gentistic acid at pH = 5. The quality control tests revealed ~98% labeling efficiency. Paper chromatographic (PC) and instant thin-layer chromatographic (ITLC) techniques were used to analyze radiochemical yield. Biodistribution and infection specificity of the radiotracer were performed with Escherichia coli (E. coli) infection-induced rats. Scintigraphy and glomerular filtration rate (GFR) study was performed in E. coli-infected rabbits. Scintigraphy indicated E. coli infection targeting potential of 99m Tc-SDZ, while biodistribution study showed minimal uptake of 99m Tc-SDZ in non-targeted tissues. The uptake in the kidneys was found 2.56 ± 0.06, 2.09 ± 0.10, and 1.68 ± 0.09% at 30 min, 1 h, and 4 h, respectively. The infected muscle (target) to non-infected muscle (non-target) ratio (T/NT) was found 4.49 ± 0.04, 6.78 ± 0.07, and 5.59 ± 0.08 at 30 min, 1 h, and 4 h, respectively.

Self-assembled three-dimensional and compressible interdigitated thin-film supercapacitors and batteries

PubMed Central

Nyström, Gustav; Marais, Andrew; Karabulut, Erdem; Wågberg, Lars; Cui, Yi; Hamedi, Mahiar M.

2015-01-01

Traditional thin-film energy-storage devices consist of stacked layers of active films on two-dimensional substrates and do not exploit the third dimension. Fully three-dimensional thin-film devices would allow energy storage in bulk materials with arbitrary form factors and with mechanical properties unique to bulk materials such as compressibility. Here we show three-dimensional energy-storage devices based on layer-by-layer self-assembly of interdigitated thin films on the surface of an open-cell aerogel substrate. We demonstrate a reversibly compressible three-dimensional supercapacitor with carbon nanotube electrodes and a three-dimensional hybrid battery with a copper hexacyanoferrate ion intercalating cathode and a carbon nanotube anode. The three-dimensional supercapacitor shows stable operation over 400 cycles with a capacitance of 25 F g−1 and is fully functional even at compressions up to 75%. Our results demonstrate that layer-by-layer self-assembly inside aerogels is a rapid, precise and scalable route for building high-surface-area 3D thin-film devices. PMID:26021485

Thin film electronic devices with conductive and transparent gas and moisture permeation barriers

DOEpatents

Simpson, Lin Jay

2013-12-17

A thin film stack (100, 200) is provided for use in electronic devices such as photovoltaic devices. The stack (100, 200) may be integrated with a substrate (110) such as a light transmitting/transmissive layer. A electrical conductor layer (120, 220) is formed on a surface of the substrate (110) or device layer such as a transparent conducting (TC) material layer (120,220) with pin holes or defects (224) caused by manufacturing. The stack (100) includes a thin film (130, 230) of metal that acts as a barrier for environmental contaminants (226, 228). The metal thin film (130,230) is deposited on the conductor layer (120, 220) and formed from a self-healing metal such as a metal that forms self-terminating oxides. A permeation plug or block (236) is formed in or adjacent to the thin film (130, 230) of metal at or proximate to the pin holes (224) to block further permeation of contaminants through the pin holes (224).

Fabrication of read-only type triple-layered disc

NASA Astrophysics Data System (ADS)

Yang, Huei Wen; Jeng, Tzuan Ren; Yen, Wen Hsin; Chan, Rong Po; Shin, Kuo Ding; Huang, Der Ray

2003-06-01

The approach to increase optical recording density has become very popular research subject in these years. One direct and effective method is to increase the recording layer stack number. That is to say, to add one more recording layer can get one more recording capacity. In this paper, we will propose a new method for manufacturing read only type multi-layered disc. The process is described in the following. This first recorded data layer (called L0) still follows the traditional DVD disc manufacturing process. We obtain the polycarbonate substrate by replicating from Ni stamper. Then polycarbonate substrate is sputtered thin silicon film for semi-reflection layer. As for second layer (L1) and even more layer (Ln-1) producing, one special kind of duplication (called SKD) method is proposed. The duplication (or replication) source of second or nth recorded data is not only limited from Ni stamper. Even polycarbonate or PMMA substrate has recording data are also acceptable sources. At next step, the duplication source is deposited by thin gold film. Then we apply spin coating to bond the first layer (L0) substrate and second layer (L1) duplication source by choosing suitable UV curing glue. After being emitted by UV lamp for several seconds, we can easily separate the duplication source of second layer (L1) from (L0) substrate. Then we find the thin second data layer (L1) is replicated and stacks upon the first layer. On the same way, we sputter thin AgTi layer on the thin second data layer for another semi- reflective layer. By following the above manufacture step, we can produce more layers. In our experimental, we prepare triple layered read-only type disc. The total capacity is almost 12GB for one side of disc, and 24GB for two side of disc. The read-out intensity of laser from each data layer is expected to be similar. Thus we have designed particular reflectance and transmittance for each data layer by controlling the thickness of thin silicon film. We can verify our design by checking the focusing error signal in S-curve search of optical pickup head. The signal quality for each layer can be found from the signal eye pattern and jitter. For compatibility with present drive system, the requirement of the readout signal from each layer should be same as DVD or CD specification

Insight into the epitaxial encapsulation of Pd catalysts in an oriented metalloporphyrin network thin film for tandem catalysis.

PubMed

Vohra, M Ismail; Li, De-Jing; Gu, Zhi-Gang; Zhang, Jian

2017-06-14

A palladium catalyst (Pd-Cs) encapsulated metalloporphyrin network PIZA-1 thin film with bifunctional properties has been developed through a modified epitaxial layer-by-layer encapsulation approach. Combining the oxidation activity of Pd-Cs and the acetalization activity of the Lewis acidic sites in the PIZA-1 thin film, this bifunctional catalyst of the Pd-Cs@PIZA-1 thin film exhibits a good catalytic activity in a one-pot tandem oxidation-acetalization reaction. Furthermore, the surface components can be controlled by ending the top layer with different precursors in the thin film preparation procedures. The catalytic performances of these thin films with different surface composites were studied under the same conditions, which showed different reaction conversions. The result revealed that the surface component can influence the catalytic performance of the thin films. This epitaxial encapsulation offers a good understanding of the tandem catalysis for thin film materials and provides useful guidance to develop new thin film materials with catalytic properties.

Use of a thin-layer technique in thyroid fine needle aspiration.

PubMed

Malle, Despoina; Valeri, Rosalia-Maria; Pazaitou-Panajiotou, Kalliopi; Kiziridou, Anastasia; Vainas, Iraklis; Destouni, Charicleia

2006-01-01

To investigate the efficacy of the ThinPrep Processor (Cytyc Corporation, Boxborough, Massachusetts, U.S.A) in fine needle aspiration (FNA) of thyroid gland lesions. This study included 459 thyroid FNA specimens obtained from patients who came to our endocrinology department with various thyroid disorders over 3 years. The cytologic material was prepared using both the conventional and ThinPrep method in the first 2 years (285 cases), while in the last one only the ThinPrep method was used (1 74 cases). The smears were stained using a modified Papanicolaou procedure and May-Grünwald-Giemsa stain. Immunocytochemistry was performed on thin-layer slides using specific monoclonal antibodies when needed. Thin-layer and direct smear diagnoses were compared with the final cytologic or histologic diagnoses, when available. Our cases included 279 adenomatoid nodules, 15 cases of Hashimoto thyroiditis, 45 follicular neoplasms, 14 Hürthle cell tumors, 58 papillary carcinomas and 1 5 anaplastic carcinomas. Thin-layer preparations showed a trend toward a lower proportion of inadequate specimens and a lower false negative rate. Cytomorphologic features showed some differences between the 2 methods. Colloid was less frequently observed on ThinPrep slides, while nuclear detail and micronucleoli were more easily detected with this technique. Moreover, ThinPrep appeared to be the appropriate method for the use of ancillary techniques in suspicious cases. Thin-layer cytology improves the diagnostic accuracy of thyroid FNA and offers the possibility of performing new techniques, such as immunocytochemistry, on the same sample in order to detect malignancy as well as the type and origin of thyroid gland neoplasms.

Photovoltaic sub-cell interconnects

DOE Office of Scientific and Technical Information (OSTI.GOV)

van Hest, Marinus Franciscus Antonius Maria; Swinger Platt, Heather Anne

2017-05-09

Photovoltaic sub-cell interconnect systems and methods are provided. In one embodiment, a photovoltaic device comprises a thin film stack of layers deposited upon a substrate, wherein the thin film stack layers are subdivided into a plurality of sub-cells interconnected in series by a plurality of electrical interconnection structures; and wherein the plurality of electrical interconnection structures each comprise no more than two scribes that penetrate into the thin film stack layers.

Effect of atmospheric-pressure plasma treatment on the adhesion properties of a thin adhesive layer in a selective transfer process

NASA Astrophysics Data System (ADS)

Yoon, Min-Ah; Kim, Chan; Hur, Min; Kang, Woo Seok; Kim, Jaegu; Kim, Jae-Hyun; Lee, Hak-Joo; Kim, Kwang-Seop

2018-01-01

The adhesion between a stamp and thin film devices is crucial for their transfer on a flexible substrate. In this paper, a thin adhesive silicone layer on the stamp was treated by atmospheric pressure plasma to locally control the adhesion strength for the selective transfer. The adhesion strength of the silicone layer was significantly reduced after the plasma treatment, while its surface energy was increased. To understand the inconsistency between the adhesion strength and surface energy changes, the surface properties of the silicone layer were characterized using nanoindentation and X-ray photoelectron spectroscopy. These techniques revealed that a thin, hard, silica-like layer had formed on the surface from plasma-enhanced oxidation. This layer played an important role in decreasing the contact area and increasing the interfacial slippage, resulting in decreased adhesion. As a practical application, the transfer process was demonstrated on GaN LEDs that had been previously delaminated by a laser lift-off (LLO) process. Although the LEDs were not transferred onto the treated adhesive layer due to the reduced adhesion, the untreated adhesive layer could readily pick up the LEDs. It is expected that this simple method of controlling the adhesion of a stamp with a thin adhesive layer would enable a continuous, selective and large-scale roll-to-roll selective transfer process and thereby advance the development of flexible, stretchable and wearable electronics.

Study on the growth mechanism and optical properties of sputtered lead selenide thin films

NASA Astrophysics Data System (ADS)

Sun, Xigui; Gao, Kewei; Pang, Xiaolu; Yang, Huisheng; Volinsky, Alex A.

2015-11-01

Lead selenide thin films with different microstructure were deposited on Si (1 0 0) substrates using magnetron sputtering at 50 °C, 150 °C and 250 °C, respectively. The crystal structure of the sputtered PbSe thin films varies from amorphous crystalline to columnar grain, and then to double-layer (nano-crystalline layer and columnar grain layer) structure as the deposition temperature increases, which is due to the dominating growth mode of the thin films changes from Frank-van der Merwe (or layer-by-layer) growth mode at 50 °C to Volmer-Weber (or 3D island) growth mode at 150 °C, and then to Stranski-Krastanow (or 3D island-on-wetting-layer) growth mode at 250 °C. The growth mechanism of the sputtered PbSe thin films is mainly dominated by the surface and strain energy contributions. Moreover, the strain energy contribution is more prominent when the deposition temperature is less than 180 °C, while, the surface energy contribution is more prominent when the deposition temperature is higher than 180 °C. The absorption spectra of the sputtered PbSe thin films are in 3.1-5 μm range. Besides, the sputtered PbSe thin film prepared at 250 °C has two different optical band gaps due to its unique double-layer structure. According to the theoretical calculation results, the variation of the band gap with the deposition temperature is determined by the shift of the valence band maximum with the lattice constant.

Synthesis and characterization of Zn(O,OH)S and AgInS2 layers to be used in thin film solar cells

NASA Astrophysics Data System (ADS)

Vallejo, W.; Arredondo, C. A.; Gordillo, G.

2010-11-01

In this paper AgInS2 and Zn(O,OH)S thin films were synthesized and characterized. AgInS2 layers were grown by co-evaporation from metal precursors in a two-step process, and, Zn(O,OH)S thin films were deposited from chemical bath containing thiourea, zinc acetate, sodium citrate and ammonia. X-ray diffraction measurements indicated that AgInS2 thin films grown with chalcopyrite structure, and the as-grown Zn(O,OH)S thin films were polycrystalline. It was also found that the AgInS2 films presented p-type conductivity, a high absorption coefficient (greater than 104 cm-1) and energy band-gap Eg of about 1.95 eV, Zn(O,OH),S thin films presented Eg of about 3.89 eV. Morphological analysis showed that under this synthesis conditions Zn(O,OH),S thin films coated uniformly the absorber layer. Additionally, the Zn(O,OH)S kinetic growth on AgInS2 layer was studied also. Finally, the results suggest that these layers possibly could be used in one-junction solar cells and/or as top cell in a tandem solar cell.

Deformation behavior of coherently strained InAs/GaAs(111)A heteroepitaxial systems: Theoretical calculations and experimental measurements

NASA Astrophysics Data System (ADS)

Zepeda-Ruiz, Luis A.; Pelzel, Rodney I.; Nosho, Brett Z.; Weinberg, W. Henry; Maroudas, Dimitrios

2001-09-01

A comprehensive, quantitative analysis is presented of the deformation behavior of coherently strained InAs/GaAs(111)A heteroepitaxial systems. The analysis combines a hierarchical theoretical approach with experimental measurements. Continuum linear elasticity theory is linked with atomic-scale calculations of structural relaxation for detailed theoretical studies of deformation in systems consisting of InAs thin films on thin GaAs(111)A substrates that are mechanically unconstrained at their bases. Molecular-beam epitaxy is used to grow very thin InAs films on both thick and thin GaAs buffer layers on epi-ready GaAs(111)A substrates. The deformation state of these samples is characterized by x-ray diffraction (XRD). The interplanar distances of thin GaAs buffer layers along the [220] and [111] crystallographic directions obtained from the corresponding XRD spectra indicate clearly that thin buffer layers deform parallel to the InAs/GaAs(111)A interfacial plane, thus aiding in the accommodation of the strain induced by lattice mismatch. The experimental measurements are in excellent agreement with the calculated lattice interplanar distances and the corresponding strain fields in the thin mechanically unconstrained substrates considered in the theoretical analysis. Therefore, this work contributes direct evidence in support of our earlier proposal that thin buffer layers in layer-by-layer semiconductor heteroepitaxy exhibit mechanical behavior similar to that of compliant substrates [see, e.g., B. Z. Nosho, L. A. Zepeda-Ruiz, R. I. Pelzel, W. H. Weinberg, and D. Maroudas, Appl. Phys. Lett. 75, 829 (1999)].

Self-assembly of dodecaphenyl POSS thin films

NASA Astrophysics Data System (ADS)

Handke, Bartosz; Klita, Łukasz; Niemiec, Wiktor

2017-12-01

The self-assembly abilities of Dodecaphenyl Polyhedral Oligomeric Silsesquioxane thin films on Si(1 0 0) surfaces were studied. Due to their thermal properties - relatively low sublimation temperature and preservation of molecular structure - cage type silsesquioxanes are ideal material for the preparation of a thin films by Physical Vapor Deposition. The Ultra-High Vacuum environment and the deposition precision of the PVD method enable the study of early stages of thin film growth and its molecular organization. X-ray Reflectivity and Atomic Force Microscopy measurements allow to pursuit size-effects in the structure of thin films with thickness ranges from less than a single molecular layer up to several tens of layers. Thermal treatment of the thin films triggered phase change: from a poorly ordered polycrystalline film into a well-ordered multilayer structure. Self-assembly of the layers is the effect of the π-stacking of phenyl rings, which force molecules to arrange in a superlattice, forming stacks of alternating organic-inorganic layers.

Effect of Al doping on performance of ZnO thin film transistors

NASA Astrophysics Data System (ADS)

Dong, Junchen; Han, Dedong; Li, Huijin; Yu, Wen; Zhang, Shendong; Zhang, Xing; Wang, Yi

2018-03-01

In this work, we investigate the Aluminum-doped Zinc Oxide (AZO) thin films and their feasibility as the active layer for thin film transistors (TFTs). A comparison on performance is made between the AZO TFTs and ZnO TFTs. The electrical properties such as saturation mobility, subthreshold swing, and on-to-off current ratio are improved when AZO is utilized as the active layer. Oxygen component of the thin film materials indicates that Al is the suppressor for oxygen defect in active layer, which improves the subthreshold swing. Moreover, based on band structure analyzation, we observe that the carrier concentration of AZO is higher than ZnO, leading to the enhancement of saturation mobility. The microstructure of the thin films convey that the AZO films exhibit much smaller grain boundaries than ZnO films, which results in the lower off-state current and higher on-to-off current ratio of AZO TFTs. The AZO thin films show huge potential to be the active layer of TFTs.

Thin film photovoltaic device with multilayer substrate

DOEpatents

Catalano, Anthony W.; Bhushan, Manjul

1984-01-01

A thin film photovoltaic device which utilizes at least one compound semiconductor layer chosen from Groups IIB and VA of the Periodic Table is formed on a multilayer substrate The substrate includes a lowermost support layer on which all of the other layers of the device are formed. Additionally, an uppermost carbide or silicon layer is adjacent to the semiconductor layer. Below the carbide or silicon layer is a metal layer of high conductivity and expansion coefficient equal to or slightly greater than that of the semiconductor layer.

Controlled placement and orientation of nanostructures

DOEpatents

Zettl, Alex K; Yuzvinsky, Thomas D; Fennimore, Adam M

2014-04-08

A method for controlled deposition and orientation of molecular sized nanoelectromechanical systems (NEMS) on substrates is disclosed. The method comprised: forming a thin layer of polymer coating on a substrate; exposing a selected portion of the thin layer of polymer to alter a selected portion of the thin layer of polymer; forming a suspension of nanostructures in a solvent, wherein the solvent suspends the nanostructures and activates the nanostructures in the solvent for deposition; and flowing a suspension of nanostructures across the layer of polymer in a flow direction; thereby: depositing a nanostructure in the suspension of nanostructures only to the selected portion of the thin layer of polymer coating on the substrate to form a deposited nanostructure oriented in the flow direction. By selectively employing portions of the method above, complex NEMS may be built of simpler NEMSs components.

Assessment of antioxidant activity in Victorian marine algal extracts using high performance thin-layer chromatography and multivariate analysis.

PubMed

Agatonovic-Kustrin, Snezana; Morton, David W; Ristivojević, Petar

2016-10-14

The aim of this study was to develop and validate a rapid and simple high performance thin layer chromatographic (HPTLC) method to screen for antioxidant activity in algal samples. 16 algal species were collected from local Victorian beaches. Fucoxanthin, one of the most abundant marine carotenoids was quantified directly from the HPTLC plates before derivatization, while derivatization either with 2,2-diphenyl-1-picrylhydrazyl (DPPH) or ferric chloride (FeCl 3 ) was used to analyze antioxidants in marine algae, based on their ability to scavenge non biological stable free radical (DPPH) or to chelate iron ions. Principal component analysis of obtained HPTLC fingerprints has classified algae species into 5 groups according to their chemical/antioxidant profiles. The investigated brown algae samples were found to be rich in non-and moderate-polar compounds and phenolic compounds with antioxidant activity. Most of the phenolic iron chelators also have shown free radical scavenging activity. Strong positive and significant correlations between total phenolic content and DPPH radical scavenging activity showed that, phenolic compounds, including flavonoids are the main contributors of antioxidant activity in these species. The results suggest that certain brown algae possess significantly higher antioxidant potential when compared to red or green algae and could be considered for future applications in medicine, dietary supplements, cosmetics or food industries. Cystophora monilifera extract was found to have the highest antioxidant concentration, followed by Zonaria angustata, Cystophora pectinate, Codium fragile, and Cystophora pectinata. Fucoxanthin was found mainly in the brown algae species. The proposed methods provide an edge in terms of screening for antioxidants and quantification of antioxidant constituents in complex mixtures. The current application also demonstrates flexibility and versatility of a standard HPTLC system in the drug discovery. Proposed methods could be used for the bioassay-guided isolation of unknown natural antioxidants and subsequent identification if combined with spectroscopic identification. Copyright © 2016 Elsevier B.V. All rights reserved.

Effect of inserting a hole injection layer in organic light-emitting diodes: A numerical approach

NASA Astrophysics Data System (ADS)

Lee, Hyeongi; Hwang, Youngwook; Won, Taeyoung

2015-01-01

For investigating the effect of inserting a hole injection layer (HIL), we carried out a computational study concerning organic light-emitting diodes (OLEDs) that had a thin CuPc layer as the hole injection layer. We used S-TAD (2, 2', 7, 7'-tetrakis-(N, Ndiphenylamino)-9, 9-spirobifluoren) for the hole transfer layer, S-DPVBi (4, 4'-bis (2, 2'-diphenylvinyl)-1, 1'-spirobiphenyl) for the emission layer and Alq3 (Tris (8-hyroxyquinolinato) aluminium) for the electron transfer layer. This tri-layer device was compared with four-layer devices. To this tri-layer device, we added a thin CuPc layer, which had a 5.3 eV highest occupied molecular orbital (HOMO) level and a 3.8 eV lowest unoccupied molecular orbital (LUMO) level, as a hole injection layer, and we chose this device for Device A. Also, we varied the LUMO level or the HOMO level of the thin CuPc layer. These two devices were identified as Device C and Device D, respectively. In this paper, we simulated the carrier injection, transport and recombination in these four devices. Thereby, we showed the effect of the HIL, and we demonstrated that the characteristics of these devices were improved by adding a thin layer of CuPc between the anode and the HTL.

Fabrication of ATO/Graphene Multi-layered Transparent Conducting Thin Films

NASA Astrophysics Data System (ADS)

Li, Na; Chen, Fei; Shen, Qiang; Wang, Chuanbin; Zhang, Lianmeng

2013-03-01

A novel transparent conducting oxide based on the ATO/graphene multi-layered thin films has been developed to satisfy the application of transparent conductive electrode in solar cells. The ATO thin films are prepared by pulsed laser deposition method with high quality, namely the sheet resistance of 49.5 Ω/sq and average transmittance of 81.9 %. The prepared graphene sheet is well reduced and shows atomically thin, spotty distributed appearance on the top of the ATO thin films. The XRD and optical micrographs are used to confirm the successfully preparation of the ATO/graphene multi-layered thin films. The Hall measurements and UV-Vis spectrophotometer are conducted to evaluate the sheet resistance and optical transmittance of the innovative structure. It is found that graphene can improve the electrical properties of the ATO thin films with little influence on the optical transmittance.

Oriented conductive oxide electrodes on SiO2/Si and glass

DOEpatents

Jia, Quanxi; Arendt, Paul N.

2001-01-01

A thin film structure is provided including a silicon substrate with a layer of silicon dioxide on a surface thereof, and a layer of cubic oxide material deposited upon the layer of silicon dioxide by ion-beam-assisted-deposition, said layer of cubic oxide material characterized as biaxially oriented. Preferably, the cubic oxide material is yttria-stabilized zirconia. Additional thin layers of biaxially oriented ruthenium oxide or lanthanum strontium cobalt oxide are deposited upon the layer of yttria-stabilized zirconia. An intermediate layer of cerium oxide is employed between the yttria-stabilized zirconia layer and the lanthanum strontium cobalt oxide layer. Also, a layer of barium strontium titanium oxide can be upon the layer of biaxially oriented ruthenium oxide or lanthanum strontium cobalt oxide. Also, a method of forming such thin film structures, including a low temperature deposition of a layer of a biaxially oriented cubic oxide material upon the silicon dioxide surface of a silicon dioxide/silicon substrate is provided.

Damped response of shells by a constrained viscoelastic layer

NASA Technical Reports Server (NTRS)

El-Raheb, M.; Wagner, P.

1986-01-01

Vibration absorbers are introduced into an asymmetric configuration of thin cylinders and tori enclosing an acoustic medium. The absorbers consist of thin axial strips bonded to the cylinder with a thin viscoelastic layer. The constrained layer dissipates the energy of relative motions between strip and cylinder. The absorber is most effective on response modes with two or more circumferential waves. The use of transfer matrices is extended to the coupled cylinder-absorber system.

Photocurrent generation in SnO2 thin film by surface charged chemisorption O ions

NASA Astrophysics Data System (ADS)

Lee, Po-Ming; Liao, Ching-Han; Lin, Chia-Hua; Liu, Cheng-Yi

2018-06-01

We report a photocurrent generation mechanism in the SnO2 thin film surface layer by the charged chemisorption O ions on the SnO2 thin film surface induced by O2-annealing. A critical build-in electric field in the SnO2 surface layer resulted from the charged O ions on SnO2 surface prolongs the lifetime and reduces the recombination probability of the photo-excited electron-hole pairs by UV-laser irradiation (266 nm) in the SnO2 surface layer, which is the key for the photocurrent generation in the SnO2 thin film surface layer. The critical lifetime of prolonged photo-excited electron-hole pair is calculated to be 8.3 ms.

Multi-oxide active layer deposition using Applied Materials Pivot array coater for high-mobility metal oxide TFT

NASA Astrophysics Data System (ADS)

Park, Hyun Chan; Scheer, Evelyn; Witting, Karin; Hanika, Markus; Bender, Marcus; Hsu, Hao Chien; Yim, Dong Kil

2015-11-01

By controlling a thin indium tin oxide (ITO), indium zinc oxide interface layer between gate insulator and indium gallium zinc oxide (IGZO), the thin-film transistor (TFT) performance can reach higher mobility as conventional IGZO as well as superior stability. For large-area display application, Applied Materials static PVD array coater (Applied Materials GmbH & Co. KG, Alzenau, Germany) using rotary targets has been developed to enable uniform thin layer deposition in display industry. Unique magnet motion parameter optimization in Pivot sputtering coater is shown to provide very uniform thin ITO layer to reach TFT performance with high mobility, not only on small scale, but also on Gen8.5 (2500 × 2200 mm glass size) production system.

Highly stable thin film transistors using multilayer channel structure

NASA Astrophysics Data System (ADS)

Nayak, Pradipta K.; Wang, Zhenwei; Anjum, D. H.; Hedhili, M. N.; Alshareef, H. N.

2015-03-01

We report highly stable gate-bias stress performance of thin film transistors (TFTs) using zinc oxide (ZnO)/hafnium oxide (HfO2) multilayer structure as the channel layer. Positive and negative gate-bias stress stability of the TFTs was measured at room temperature and at 60 °C. A tremendous improvement in gate-bias stress stability was obtained in case of the TFT with multiple layers of ZnO embedded between HfO2 layers compared to the TFT with a single layer of ZnO as the semiconductor. The ultra-thin HfO2 layers act as passivation layers, which prevent the adsorption of oxygen and water molecules in the ZnO layer and hence significantly improve the gate-bias stress stability of ZnO TFTs.

Method of manufacturing a shapeable short-resistant capacitor

DOEpatents

Taylor, Ralph S.; Myers, John D.; Baney, William J.

2013-04-02

A method that employs a novel combination of conventional fabrication techniques provides a ceramic short-resistant capacitor that is bendable and/or shapeable to provide a multiple layer capacitor that is extremely compact and amenable to desirable geometries. The method allows thinner and more flexible ceramic capacitors to be made. The method includes forming a first thin metal layer on a substrate; depositing a thin, ceramic dielectric layer over the metal layer; depositing a second thin metal layer over the dielectric layer to form a capacitor exhibiting a benign failure mode; and separating the capacitor from the substrate. The method may also include bending the resulting capacitor into a serpentine arrangement with gaps between the layers that allow venting of evaporated electrode material in the event of a benign failure.

Method and apparatus for fabricating a thin-film solar cell utilizing a hot wire chemical vapor deposition technique

DOEpatents

Wang, Qi; Iwaniczko, Eugene

2006-10-17

A thin-film solar cell is provided. The thin-film solar cell comprises an a-SiGe:H (1.6 eV) n-i-p solar cell having a deposition rate of at least ten (10) .ANG./second for the a-SiGe:H intrinsic layer by hot wire chemical vapor deposition. A method for fabricating a thin film solar cell is also provided. The method comprises depositing a n-i-p layer at a deposition rate of at least ten (10) .ANG./second for the a-SiGe:H intrinsic layer.

Ultra-high current density thin-film Si diode

DOEpatents

Wang; Qi

2008-04-22

A combination of a thin-film .mu.c-Si and a-Si:H containing diode structure characterized by an ultra-high current density that exceeds 1000 A/cm.sup.2, comprising: a substrate; a bottom metal layer disposed on the substrate; an n-layer of .mu.c-Si deposited the bottom metal layer; an i-layer of .mu.c-Si deposited on the n-layer; a buffer layer of a-Si:H deposited on the i-layer, a p-layer of .mu.c-Si deposited on the buffer layer; and a top metal layer deposited on the p-layer.

Electron transport in ultra-thin films and ballistic electron emission microscopy

NASA Astrophysics Data System (ADS)

Claveau, Y.; Di Matteo, S.; de Andres, P. L.; Flores, F.

2017-03-01

We have developed a calculation scheme for the elastic electron current in ultra-thin epitaxial heterostructures. Our model uses a Keldysh’s non-equilibrium Green’s function formalism and a layer-by-layer construction of the epitaxial film. Such an approach is appropriate to describe the current in a ballistic electron emission microscope (BEEM) where the metal base layer is ultra-thin and generalizes a previous one based on a decimation technique appropriated for thick slabs. This formalism allows a full quantum mechanical description of the transmission across the epitaxial heterostructure interface, including multiple scattering via the Dyson equation, which is deemed a crucial ingredient to describe interfaces of ultra-thin layers properly in the future. We introduce a theoretical formulation needed for ultra-thin layers and we compare with results obtained for thick Au(1 1 1) metal layers. An interesting effect takes place for a width of about ten layers: a BEEM current can propagate via the center of the reciprocal space (\\overlineΓ ) along the Au(1 1 1) direction. We associate this current to a coherent interference finite-width effect that cannot be found using a decimation technique. Finally, we have tested the validity of the handy semiclassical formalism to describe the BEEM current.

Lidar observation of transition of cirrus clouds over a tropical station Gadanki (13.45° N, 79.18° E): case studies

NASA Astrophysics Data System (ADS)

Srinivasan, M. A.; Rao, C. Dhananjaya; Krishnaiah, M.

2016-05-01

The present study describes Mie lidar observations of the cirrus cloud passage showing transition between double thin layers into single thick and single thick layer into double thin layers of cirrus over Gadanki region. During Case1: 17 January 2007, Case4: 12 June 2007, Case5: 14 July 2007 and Case6: 24 July 2007 the transition is found to from two thin cirrus layers into single geometrically thick layer. Case2: 14 May 2007 and Case3: 15 May 2007, the transition is found to from single geometrically thick layer into two thin cirrus layers. Linear Depolarization Ratio (LDR) and Back Scatter Ration (BSR) are found to show similar variation with strong peaks during transition; both LDR and Cloud Optical Depth (COD) is found to show similar variation except during transition with strong peaks in COD which is not clearly found from LDR for the all cases. There is a significant weakening of zonal and meridional winds during Case1 which might be due to the transition from multiple to single thick cirrus indicating potential capability of thick cirrus in modulating the wind fields. There exists strong upward wind dominance contributed to significant ascent in cloud-base altitude thereby causing transition of multiple thin layers into single thick cirrus.

Patterning layer-by-layer self-assembled multilayer by lithography and its applications to thin film devices

NASA Astrophysics Data System (ADS)

Hua, Feng

Nanoparticles are exciting materials because they exhibit unique electronic, catalytic, and optical properties. As a novel and promising nanobuilding block, it attracts considerable research efforts in its integration into a wide variety of thin film devices. Nanoparticles were adsorbed onto the substrate with layer-by-layer self-assembly which becomes of great interest due to its suitability in colloid particle assembly. Without extremely high temperatures and sophisticated equipment, molecularly organized films in an exactly pre-designed order can grow on almost all the substrates in nature. Two approaches generating spatially separated patterns comprised of nanoparticles are demonstrated, as well as two approaches patterning more than one type of nonoparticle on a silicon wafer. The structure of the thin film patterned by these approaches are analyzed and considered suitable to the thin film device. Finally, the combination of lithography and layer-by-layer (lbl) self-assembly is utilized to realize the microelectronic device with functional nonoparticles. The lbl self-assembly is the way to coat the nonoparticles and the lighography to pattern them. Based on the coating and patterning technique, a MOS-capacitor, a MOS field-effect-transistor and magnetic thin film cantilever are fabricated.

Thin and thick layers of resin-based sealer cement bonded to root dentine compared: Adhesive behaviour.

PubMed

Pane, Epita S; Palamara, Joseph E A; Messer, Harold H

2015-12-01

This study aims to evaluate tensile and shear bond strengths of one epoxy (AH) and two methacrylate resin-based sealers (EZ and RS) in thin and thick layers bonded to root dentine. An alignment device was prepared for accurate positioning of 20 root dentine cylinders in a predefined gap of 0.1 or 1 mm. Sealer was placed in the interface. Bond strength tests were conducted. Mode of failures and representative surfaces were evaluated. Data were analysed using anova and post-hoc tests, with P < 0.05. The thick layer of sealer produced higher bond strength, except for the shear bond strength of EZ. Significant differences between thin and thick layers were found only in tensile bond strengths of AH and RS. Mixed type of failure was constantly found with all sealers. Bond strengths of thick layers of resin-based sealers to root dentine tended to be higher than with thin layers. © 2015 Australian Society of Endodontology.

Method of Fabricating Schottky Barrier solar cell

NASA Technical Reports Server (NTRS)

Stirn, R. J.; Yeh, Y. C. M. (Inventor)

1982-01-01

On a thin substrate of low cost material with at least the top surface of the substrate being electrically conductive is deposited a thin layer of heavily doped n-type polycrystalline germanium, with crystalline sizes in the submicron range. A passivation layer may be deposited on the substrate to prevent migration of impurities into the polycrystalline germanium. The polycrystalline germanium is recrystallized to increase the crystal sizes in the germanium layer to not less than 5 micros to serve as a base layer on which a thin layer of gallium arsenide is vapor epitaxially grown to a selected thickness. A thermally-grown oxide layer of a thickness of several tens of angstroms is formed on the gallium arsenide layer. A metal layer, of not more about 100 angstroms thick, is deposited on the oxide layer, and a grid electrode is deposited to be in electrical contact with the top surface of the metal layer. An antireflection coating may be deposited on the exposed top surface of the metal layer.

Characterization of aluminum selenide bi-layer thin film

NASA Astrophysics Data System (ADS)

Boolchandani, Sarita; Soni, Gyanesh; Srivastava, Subodh; Vijay, Y. K.

2018-05-01

The Aluminum Selenide (AlSe) bi-layer thin films were grown on glass substrate using thermal evaporation method under high vacuum condition. The morphological characterization was done using SEM. Electrical measurement with temperature variation shows that thin films exhibit the semiconductor nature. The optical properties of prepared thin films have also been characterized by UV-VIS spectroscopy measurements. The band gap of composite thin films has been calculated by Tauc's relation at different temperature ranging 35°C-100°C.

Piezoresistivity of mechanically drawn single-walled carbon nanotube (SWCNT) thin films-: mechanism and optimizing principle

NASA Astrophysics Data System (ADS)

Obitayo, Waris

The individual carbon nanotube (CNT) based strain sensors have been found to have excellent piezoresistive properties with a reported gauge factor (GF) of up to 3000. This GF on the other hand, has been shown to be structurally dependent on the nanotubes. In contrast, to individual CNT based strain sensors, the ensemble CNT based strain sensors have very low GFs e.g. for a single walled carbon nanotube (SWCNT) thin film strain sensor, GF is ~1. As a result, studies which are mostly numerical/analytical have revealed the dependence of piezoresistivity on key parameters like concentration, orientation, length and diameter, aspect ratio, energy barrier height and Poisson ratio of polymer matrix. The fundamental understanding of the piezoresistive mechanism in an ensemble CNT based strain sensor still remains unclear, largely due to discrepancies in the outcomes of these numerical studies. Besides, there have been little or no experimental confirmation of these studies. The goal of my PhD is to study the mechanism and the optimizing principle of a SWCNT thin film strain sensor and provide experimental validation of the numerical/analytical investigations. The dependence of the piezoresistivity on key parameters like orientation, network density, bundle diameter (effective tunneling area), and length is studied, and how one can effectively optimize the piezoresistive behavior of a SWCNT thin film strain sensors. To reach this goal, my first research accomplishment involves the study of orientation of SWCNTs and its effect on the piezoresistivity of mechanically drawn SWCNT thin film based piezoresistive sensors. Using polarized Raman spectroscopy analysis and coupled electrical-mechanical test, a quantitative relationship between the strain sensitivity and SWCNT alignment order parameter was established. As compared to randomly oriented SWCNT thin films, the one with draw ratio of 3.2 exhibited ~6x increase on the GF. My second accomplishment involves studying the influence of the network density on the piezoresistivity of mechanically drawn SWCNT thin films. Mechanically drawn SWCNT thin films with different layer (or thickness) e.g. 1-layer, 3-layer, 10-layer and 20-layer SWCNT thin films were prepared to understand the variation of SWCNT network density as well as the alignment of SWCNTs on the strain sensitivity. The less entangled SWCNT bundles observed in the sparse network density (1- layer and 3-layer SWCNT thin films) allows for easy alignment and the best gauge factors. As compared to the randomly oriented SWCNT thin films, the one with draw ratio of 3.2 exhibited ~8x increase on the GF for the 1-layer SWCNT thin films while the 20-layer SWCNT thin films exhibited ~3x increase in the GF. My third accomplishment examines the effect of SWCNT bundles with different diameters on the piezoresistive behavior of mechanically drawn SWCNT thin films. SWCNT thin film network of sparse morphology (1-layer) with different bundle sizes were prepared by varying the sonication duration e.g. S0.5hr, S4hr, S10hr and S20hr and using spraying coating. The GF increased by a factor of ~10 when the randomly oriented SWCNT thin film was stretched to a draw ratio of 3.2 for the S0.5hr SWCNT thin films and by a factor of ~2 for the S20hr SWCNT thin films. Three main mechanisms were attributed to this behavior e.g. effect of concentration of exfoliated nanotubes, bundle reduction due to mechanical stretching, and influence of bundle length on the alignment of SWCNTs. Furthermore, information about the average length and length distribution is very essential when investigating the influence of individual nanotube length on the strain sensitivity. With that in mind, we would use our previously developed preparative ultracentrifuge method (PUM), and our newly developed gel electrophoresis and simultaneous Raman and photoluminescence spectroscopy (GEP-SRSPL) to characterize the average length and length distribution of individual SWCNTs respectively.

Process for forming epitaxial perovskite thin film layers using halide precursors

DOEpatents

Clem, Paul G.; Rodriguez, Mark A.; Voigt, James A.; Ashley, Carol S.

2001-01-01

A process for forming an epitaxial perovskite-phase thin film on a substrate. This thin film can act as a buffer layer between a Ni substrate and a YBa.sub.2 Cu.sub.3 O.sub.7-x superconductor layer. The process utilizes alkali or alkaline metal acetates dissolved in halogenated organic acid along with titanium isopropoxide to dip or spin-coat the substrate which is then heated to about 700.degree. C. in an inert gas atmosphere to form the epitaxial film on the substrate. The YBCO superconductor can then be deposited on the layer formed by this invention.

Photo-EMF sensitivity of porous silicon thin layer-crystalline silicon heterojunction to ammonia adsorption.

PubMed

Vashpanov, Yuriy; Jung, Jae Il; Kwack, Kae Dal

2011-01-01

A new method of using photo-electromotive force in detecting gas and controlling sensitivity is proposed. Photo-electromotive force on the heterojunction between porous silicon thin layer and crystalline silicon wafer depends on the concentration of ammonia in the measurement chamber. A porous silicon thin layer was formed by electrochemical etching on p-type silicon wafer. A gas and light transparent electrical contact was manufactured to this porous layer. Photo-EMF sensitivity corresponding to ammonia concentration in the range from 10 ppm to 1,000 ppm can be maximized by controlling the intensity of illumination light.

19.5%-Efficient CuIn1-xGaxSe2 Photovoltaic Cells Using A Cd-Zn-S Buffer Layer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bhattacharya. R. N.

2008-01-01

CuIn1-xGaxSe2 (CIGS) solar cell junctions prepared by chemical-bath-deposited (CBD) Zn1-xCdxS (CdZnS), ZnS, and CdS buffer layers are discussed. A 19.52%-efficient, CIGS-based, thin-film photovoltaic device has been fabricated using a single-layer CBD CdZnS buffer layer. The mechanism that creates extensive hydroxide and oxide impurities in CBD-ZnS and CBD-CdZnS thin films (compared to CBD-CdS thin film) is presented.

Management of light absorption in extraordinary optical transmission based ultra-thin-film tandem solar cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mashooq, Kishwar; Talukder, Muhammad Anisuzzaman, E-mail: anis@eee.buet.ac.bd

2016-05-21

Although ultra-thin-film solar cells can be attractive in reducing the cost, they suffer from low absorption as the thickness of the active layer is usually much smaller than the wavelength of incident light. Different nano-photonic techniques, including plasmonic structures, are being explored to increase the light absorption in ultra-thin-film solar cells. More than one layer of active materials with different energy bandgaps can be used in tandem to increase the light absorption as well. However, due to different amount of light absorption in different active layers, photo-generated currents in different active layers will not be the same. The current mismatchmore » between the tandem layers makes them ineffective in increasing the efficiency. In this work, we investigate the light absorption properties of tandem solar cells with two ultra-thin active layers working as two subcells and a metal layer with periodically perforated holes in-between the two subcells. While the metal layer helps to overcome the current mismatch, the periodic holes increase the absorption of incident light by helping extraordinary optical transmission of the incident light from the top to the bottom subcell, and by coupling the incident light to plasmonic and photonic modes within ultra-thin active layers. We extensively study the effects of the geometry of holes in the intermediate metal layer on the light absorption properties of tandem solar cells with ultra-thin active layers. We also study how different metals in the intermediate layer affect the light absorption; how the geometry of holes in the intermediate layer affects the absorption when the active layer materials are changed; and how the intermediate metal layer affects the collection of photo-generated electron-hole pairs at the terminals. We find that in a solar cell with 6,6-phenyl C61-butyric acid methyl ester top subcell and copper indium gallium selenide bottom subcell, if the periodic holes in the metal layer are square or polygon, total absorption remains approximately the same. However, the total absorption suffers significantly if the holes are triangle. The transmission spectra of incident light into the bottom subcell, and hence the absorption, change significantly for square and circle holes if the active materials change to cadmium selenide (CdSe) and cadmium telluride (CdTe) in the top and bottom subcells, respectively. Although the intermediate metal layer may induce electron-hole pair recombination due to surface defects, the short-circuit current density of an ultra-thin plasmonic solar cell with an intermediate metal layer with two-dimensional hole array is >9% of that of a structure without the intermediate metal layer.« less

Study on the Hydrogenated ZnO-Based Thin Film Transistors. Part 1

DTIC Science & Technology

2011-04-30

IGZO film on the performance of thin film transistors 5 Chapter 2. Hydrogenation of a- IGZO channel layer in the thin film transistors 12...effect of substrate temperature during the deposition of a- IGZO film on the performance of thin film transistors Introduction The effect of substrate...temperature during depositing IGZO channel layer on the performance of amorphous indium-gallium-zinc oxide (a- IGZO

Thin-Film Power Transformers

NASA Technical Reports Server (NTRS)

Katti, Romney R.

1995-01-01

Transformer core made of thin layers of insulating material interspersed with thin layers of ferromagnetic material. Flux-linking conductors made of thinner nonferromagnetic-conductor/insulator multilayers wrapped around core. Transformers have geometric features finer than those of transformers made in customary way by machining and mechanical pressing. In addition, some thin-film materials exhibit magnetic-flux-carrying capabilities superior to those of customary bulk transformer materials. Suitable for low-cost, high-yield mass production.

Substrate spacing and thin-film yield in chemical bath deposition of semiconductor thin films

NASA Astrophysics Data System (ADS)

Arias-Carbajal Reádigos, A.; García, V. M.; Gomezdaza, O.; Campos, J.; Nair, M. T. S.; Nair, P. K.

2000-11-01

Thin-film yield in the chemical bath deposition technique is studied as a function of separation between substrates in batch production. Based on a mathematical model, it is proposed and experimentally verified in the case of CdS thin films that the film thickness reaches an asymptotic maximum with increase in substrate separation. It is shown that at a separation less than 1 mm between substrates the yield, i.e. percentage in moles of a soluble cadmium salt deposited as a thin film of CdS, can exceed 50%. This behaviour is explained on the basis of the existence of a critical layer of solution near the substrate, within which the relevant ionic species have a higher probability of interacting with the thin-film layer than of contributing to precipitate formation. The critical layer depends on the solution composition and the temperature of the bath as well as the duration of deposition. An effective value for the critical layer thickness has been defined as half the substrate separation at which 90% of the maximum film thickness for the particular bath composition, bath temperature and duration of deposition is obtained. In the case of CdS thin films studied as an example, the critical layer is found to extend from 0.5 to 2.5 mm from the substrate surface, depending on the deposition conditions.

Effects of morphological control on the characteristics of vertical-type OTFTs using Alq3.

PubMed

Kim, Young Do; Park, Jong Wook; Kang, In Nam; Oh, Se Young

2008-09-01

We have fabricated vertical-type organic thin-film transistors (OTFTs) using tris-(8-hydroxyquinoline) aluminum (Alq(3)) as an n-type active material. Vertical-type OTFT using Alq(3) has a layered structure of Al(source electrode)/Alq(3)(active layer)/Al(gate electrode)/Alq(3)(active layer)/ITO glass(drain electrode). Alq(3) thin films containing various surface morphologies could be obtained by the control of evaporation rate and substrate temperature. The effects of the morphological control of Alq(3) thin layer on the grain size and the flatness of film surface were investigated. The characteristics of vertical-type OTFT significantly influenced the growth condition of Alq(3) layer.

Disruption of vertical motility by shear triggers formation of thin phytoplankton layers.

PubMed

Durham, William M; Kessler, John O; Stocker, Roman

2009-02-20

Thin layers of phytoplankton are important hotspots of ecological activity that are found in the coastal ocean, meters beneath the surface, and contain cell concentrations up to two orders of magnitude above ambient concentrations. Current interpretations of their formation favor abiotic processes, yet many phytoplankton species found in these layers are motile. We demonstrated that layers formed when the vertical migration of phytoplankton was disrupted by hydrodynamic shear. This mechanism, which we call gyrotactic trapping, can be responsible for the thin layers of phytoplankton commonly observed in the ocean. These results reveal that the coupling between active microorganism motility and ambient fluid motion can shape the macroscopic features of the marine ecological landscape.

Enhanced electrical properties of dual-layer channel ZnO thin film transistors prepared by atomic layer deposition

NASA Astrophysics Data System (ADS)

Li, Huijin; Han, Dedong; Dong, Junchen; Yu, Wen; Liang, Yi; Luo, Zhen; Zhang, Shengdong; Zhang, Xing; Wang, Yi

2018-05-01

The thin film transistors (TFTs) with a dual-layer channel structure combing ZnO thin layer grown at 200 °C and ZnO film grown at 120 °C by atomic layer deposition are fabricated. The dual-layer channel TFT exhibits a low leakage current of 2.8 × 10-13 A, Ion/Ioff ratio of 3.4 × 109, saturation mobility μsat of 12 cm2 V-1 s-1, subthreshold swing (SS) of 0.25 V/decade. The SS value decreases to 0.18 V/decade after the annealing treatment in O2 due to the reduction of the trap states at the channel/dielectric interface and in the bulk channel layer. The enhanced performance obtained from the dual-layer channel TFTs is due to the ability of maintaining high mobility and suppressing the increase in the off-current at the same time.

Fabrication and characterization of {110}-oriented Pb(Zr,Ti)O3 thin films on Pt/SiO2/Si substrates using PdO//Pd buffer layer

NASA Astrophysics Data System (ADS)

Oshima, Naoya; Uchiyama, Kiyoshi; Ehara, Yoshitaka; Oikawa, Takahiro; Ichinose, Daichi; Tanaka, Hiroki; Sato, Tomoya; Uchida, Hiroshi; Funakubo, Hiroshi

2017-10-01

A strongly {110}-oriented perovskite-type thin film of tetragonal Pb(Zr0.4Ti0.6)O3 (PZT) was successfully obtained on a (100)Si substrate using a {101}PdO//{111}Pd thin film as a buffer layer. The {101}PdO//{111}Pd thin film buffer layer was obtained by oxidizing {111}Pd after depositing {111}Pd on a {111}Pt/TiO x /SiO2/{100}Si substrate. Using this buffer layer, a {110} c -oriented SrRuO3 (SRO) thin film was deposited by sputtering as a bottom electrode of PZT thin films. Subsequently, the {110}-oriented PZT thin film can be deposited on a (110) c SRO thin film by metal-organic chemical deposition (MOCVD) and its properties can be compared with those of PZT thin films with other orientations of {100} and {111}. Among the {100}, {110}, {111}-oriented PZT films, the {100}-oriented one showed the largest remnant polarization, which is in good agreement with those of the PZTs epitaxially grown in the 〈100〉, 〈110〉, and 〈111〉 directions. The other properties, i.e., piezoelectricity and dielectric constants, also showed similar anisotropic tendencies, which is in good agreement with the data reported in the epitaxially grown PZTs.

Modeling of Multiphase Flow through Thin Porous Layers: Application to a Polymer Electrolyte Fuel Cell (PEFC)

NASA Astrophysics Data System (ADS)

Qin, C.; Hassanizadeh, S.

2013-12-01

Multiphase flow and species transport though thin porous layers are encountered in a number of industrial applications, such as fuel cells, filters, and hygiene products. Based on some macroscale models like the Darcy's law, to date, the modeling of flow and transport through such thin layers has been mostly performed in 3D discretized domains with many computational cells. But, there are a number of problems with this approach. First, a proper representative elementary volume (REV) is not defined. Second, one needs to discretize a thin porous medium into computational cells whose size may be comparable to the pore sizes. This suggests that the traditional models are not applicable to such thin domains. Third, the interfacial conditions between neighboring layers are usually not well defined. Last, 3D modeling of a number of interacting thin porous layers often requires heavy computational efforts. So, to eliminate the drawbacks mentioned above, we propose a new approach to modeling multilayers of thin porous media as 2D interacting continua (see Fig. 1). Macroscale 2D governing equations are formulated in terms of thickness-averaged material properties. Also, the exchange of thermodynamic properties between neighboring layers is described by thickness-averaged quantities. In Comparison to previous macroscale models, our model has the distinctive advantages of: (1) it is rigorous thermodynamics-based model; (2) it is formulated in terms of thickness-averaged material properties which are easily measureable; and (3) it reduces 3D modeling to 2D leading to a very significant reduction of computation efforts. As an application, we employ the new approach in the study of liquid water flooding in the cathode of a polymer electrolyte fuel cell (PEFC). To highlight the advantages of the present model, we compare the results of water distribution with those obtained from the traditional 3D Darcy-based modeling. Finally, it is worth noting that, for specific case studies, a number of material properties in the model need to be determined experimentally, such as mass and heat exchange coefficients between neighboring layers. Fig. 1: Schematic representation of three thin porous layers, which may exchange mass, momentum, and energy. Also, a typical averaging domain (REV) is shown. Note that the layer thickness and thus the REV height can be spatially variable. Also, in reality, the layers are tightly stacked and there is no gap between them.

Effect of thin oxide layers incorporated in spin valve structures

NASA Astrophysics Data System (ADS)

Gillies, M. F.; Kuiper, A. E. T.; Leibbrandt, G. W. R.

2001-06-01

The enhancement of the magnetoresistance effect, induced by incorporating nano-oxide layers (NOLs) in a bottom-type spin valve, was studied for various preparation conditions. The effect of a NOL in the Co90Fe10 pinned layer was found to depend critically on the oxygen pressure applied to form the thin oxide film. Pressures over 10-3 Torr O2 yield oxides thicker than about 0.7 nm, which apparently deteriorate the biasing field which exists over the oxide. The magnetoresistance values can further be raised by forming a specular reflecting oxide on top of the sense layer. Promising results were obtained with an Al2O3 capping layer formed in a solid-state oxidation reaction that occurs spontaneously when a thin Al layer is deposited on the oxidized surface of the Co90Fe10 sense layer.

Water softening process

DOEpatents

Sheppard, John D.; Thomas, David G.

1976-01-01

This invention involves an improved process for softening hard water which comprises selectively precipitaing CaCO.sub.3 to form a thin layer thereof, increasing the pH of said water to precipitate magnesium as magnesium hydroxide and then filtering the resultant slurry through said layer. The CaCO.sub.3 layer serves as a thin permeable layer which has particularly useful application in cross-flow filtration applications.

Matching characteristics of different buffer layers with VO2 thin films

NASA Astrophysics Data System (ADS)

Yang, Kai; Zhang, Dongping; Liu, Yi; Guan, Tianrui; Qin, Xiaonan; Zhong, Aihua; Cai, Xingmin; Fan, Ping; Lv, Weizhong

2016-10-01

VO2 thin films were fabricated by reactive DC magnetron sputtering on different buffer layers of MgF2, Al2O3 and TiO2, respectively. The crystallinity and orientation relationship, thickness of VO2 thin films, atoms vibrational modes, optical and electrical property, surface morphology of films were characterized by X-ray diffraction, Raman scattering microscopy, step profiler, spectrophotometer, four-probe technique, and scanning electron microscopy, respectively. XRD results investigated that the films have preferential crystalline planes VO2 (011). The crystallinity of VO2 films grown on TiO2 buffer layers are superior to VO2 directly deposited on soda-lime glass. The Raman bands of the VO2 films correspond to an Ag symmetry mode of VO2 (M). The sample prepared on 100nm TiO2 buffer layer appears nanorods structure, and exhibits remarkable solar energy modulation ability as high as 5.82% in full spectrum and 23% in near infrared spectrum. Cross-sectional SEM image of the thin films samples indicate that MgF2 buffer layer has clear interface with VO2 layer. But there are serious interdiffusion phenomenons between Al2O3, TiO2 buffer layer with VO2 layer.

Isolation of Three Components from Spearmint Oil: An Exercise in Column and Thin-Layer Chromatography

ERIC Educational Resources Information Center

Davies, Don R.; Johnson, Todd M.

2007-01-01

A simple experiment for undergraduate organic chemistry students to separate a colorless mixture using column chromatography and then monitor the outcome of the separation using thin-layer chromatography (TLC) and infrared spectroscopy(IR) is described. The experiment teaches students the principle and techniques of column and thin-layer…

High performance thin film transistor with ZnO channel layer deposited by DC magnetron sputtering.

PubMed

Moon, Yeon-Keon; Moon, Dae-Yong; Lee, Sang-Ho; Jeong, Chang-Oh; Park, Jong-Wan

2008-09-01

Research in large area electronics, especially for low-temperature plastic substrates, focuses commonly on limitations of the semiconductor in thin film transistors (TFTs), in particular its low mobility. ZnO is an emerging example of a semiconductor material for TFTs that can have high mobility, while a-Si and organic semiconductors have low mobility (<1 cm2/Vs). ZnO-based TFTs have achieved high mobility, along with low-voltage operation low off-state current, and low gate leakage current. In general, ZnO thin films for the channel layer of TFTs are deposited with RF magnetron sputtering methods. On the other hand, we studied ZnO thin films deposited with DC magnetron sputtering for the channel layer of TFTs. After analyzing the basic physical and chemical properties of ZnO thin films, we fabricated a TFT-unit cell using ZnO thin films for the channel layer. The field effect mobility (micro(sat)) of 1.8 cm2/Vs and threshold voltage (Vth) of -0.7 V were obtained.

Magnetoelastic sensor for characterizing properties of thin-film/coatings

NASA Technical Reports Server (NTRS)

Bachas, Leonidas G. (Inventor); Barrett, Gary (Inventor); Grimes, Craig A. (Inventor); Kouzoudis, Dimitris (Inventor); Schmidt, Stefan (Inventor)

2004-01-01

An apparatus for determining elasticity characteristics of a thin-film layer. The apparatus comprises a sensor element having a base magnetostrictive element at least one surface of which is at least partially coated with the thin-film layer. The thin-film layer may be of a variety of materials (having a synthetic and/or bio-component) in a state or form capable of being deposited, manually or otherwise, on the base element surface, such as by way of eye-dropper, melting, dripping, brushing, sputtering, spraying, etching, evaporation, dip-coating, laminating, etc. Among suitable thin-film layers for the sensor element of the invention are fluent bio-substances, thin-film deposits used in manufacturing processes, polymeric coatings, paint, an adhesive, and so on. A receiver, preferably remotely located, is used to measure a plurality of values for magneto-elastic emission intensity of the sensor element in either characterization: (a) the measure of the plurality of values is used to identify a magneto-elastic resonant frequency value for the sensor element; and (b) the measure of the plurality of successive values is done at a preselected magneto-elastic frequency.

Scavenging of oxygen from SrTiO3 by metals and its implications for oxide thin film deposition

NASA Astrophysics Data System (ADS)

Posadas, Agham; Kormondy, Kristy; Guo, Wei; Ponath, Patrick; Kremer, Jacqueline; Hadamek, Tobias; Demkov, Alexander

SrTiO3 is a widely used substrate for the growth of other functional oxide thin films. However, SrTiO3 loses oxygen very easily during oxide thin film deposition even under relatively high oxygen pressures. In some cases, there will be an interfacial layer of oxygen-deficient SrTiO3 formed at the interface with the deposited oxide film, depending on the metals present in the film. By depositing a variety of metals layer by layer and measuring the evolution of the core level spectra of both the deposited metal and SrTiO3 using x-ray photoelectron spectroscopy, we show that there are three distinct types of behavior that occur for thin metal films on SrTiO3. We discuss the implications of these types of behavior for the growth of complex oxide thin films on SrTiO3, and which oxide thin films are expected to produce an interfacial oxygen-deficient layer depending on their elemental constituents.

Extraordinary Corrosion Protection from Polymer-Clay Nanobrick Wall Thin Films.

PubMed

Schindelholz, Eric J; Spoerke, Erik D; Nguyen, Hai-Duy; Grunlan, Jaime C; Qin, Shuang; Bufford, Daniel C

2018-06-20

Metals across all industries demand anticorrosion surface treatments and drive a continual need for high-performing and low-cost coatings. Here we demonstrate polymer-clay nanocomposite thin films as a new class of transparent conformal barrier coatings for protection in corrosive atmospheres. Films assembled via layer-by-layer deposition, as thin as 90 nm, are shown to reduce copper corrosion rates by >1000× in an aggressive H 2 S atmosphere. These multilayer nanobrick wall coatings hold promise as high-performing anticorrosion treatment alternatives to costlier, more toxic, and less scalable thin films, such as graphene, hexavalent chromium, or atomic-layer-deposited metal oxides.

Effects of V2O5/Au bi-layer electrodes on the top contact Pentacene-based organic thin film transistors

NASA Astrophysics Data System (ADS)

Borthakur, Tribeni; Sarma, Ranjit

2017-05-01

Top-contact Pentacene-based organic thin film transistors (OTFTs) with a thin layer of Vanadium Pent-oxide between Pentacene and Au layer are fabricated. Here we have found that the devices with V2O5/Au bi-layer source-drain electrode exhibit better field-effect mobility, high on-off ratio, low threshold voltage and low sub-threshold slope than the devices with Au only. The field-effect mobility, current on-off ratio, threshold voltage and sub-threshold slope of V2O5/Au bi-layer OTFT estimated from the device with 15 nm thick V2O5 layer is .77 cm2 v-1 s-1, 7.5×105, -2.9 V and .36 V/decade respectively.

Vertical III-nitride thin-film power diode

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wierer, Jr., Jonathan; Fischer, Arthur J.; Allerman, Andrew A.

2017-03-14

A vertical III-nitride thin-film power diode can hold off high voltages (kV's) when operated under reverse bias. The III-nitride device layers can be grown on a wider bandgap template layer and growth substrate, which can be removed by laser lift-off of the epitaxial device layers grown thereon.

Carbon-Nanotube Conductive Layers for Thin-Film Solar Cells

NASA Technical Reports Server (NTRS)

Landis, Geoffrey A.

2005-01-01

Thin, transparent layers comprising mats of carbon nanotubes have been proposed for providing lateral (that is, inplane) electrical conductivities for collecting electric currents from the front surfaces of the emitter layers of thin-film solar photovoltaic cells. Traditionally, thin, semitransparent films of other electrically conductive materials (usually, indium tin oxide, zinc oxide, or cadmium sulfide) have been used for this purpose. As in the cases of the traditional semitransparent conductive films, the currents collected by the nanotube layers would, in turn, be further collected by front metal contact stripes. Depending on details of a specific solar-cell design, the layer of carbon nanotubes would be deposited in addition to, or instead of, a semitransparent layer of one of these traditional conductive materials (see figure). The proposal is expected to afford the following advantages: The electrical conductivity of the carbon- nanotube layer would exceed that of the corresponding semitransparent layer of traditional electrically conductive material. The greater electrical conductivity of the carbon-nanotube layer would make it possible to retain adequate lateral electrical conductivity while reducing the thickness of, or eliminating entirely, the traditional semitransparent conductive layer. As a consequence of thinning or elimination of the traditional semitransparent conductive layer, less light would be absorbed, so that more of the incident light would be available for photovoltaic conversion. The greater electrical conductivity of the carbon-nanotube layer would make it possible to increase the distance between front metal contact stripes, in addition to (or instead of) thinning or eliminating the layer of traditional semitransparent conductive material. Consequently, the fraction of solar-cell area shadowed by front metal contact stripes would be reduced again, making more of the incident light available for photovoltaic conversion. The electrical conductivities of individual carbon nanotubes can be so high that the mat of carbon nanotubes could be made sparse enough to be adequately transparent while affording adequate lateral electrical conductivity of the mat as a whole. The thickness of the nanotube layer would be chosen so that the layer would contribute significant lateral electrical conductivity, yet would be as nearly transparent as possible to incident light. A typical thickness for satisfying these competing requirements is expected to lie between 50 and 100 nm. The optimum thickness must be calculated by comparing the lateral electrical conductivity, the distance between front metal stripes, and the amount of light lost by absorption in the nanotube layer.

Electromagnetic shielding effectiveness of a thin silver layer deposited onto PET film via atmospheric pressure plasma reduction

NASA Astrophysics Data System (ADS)

Oh, Hyo-Jun; Dao, Van-Duong; Choi, Ho-Suk

2018-03-01

This study presents the first use of a plasma reduction reaction under atmospheric pressure to fabricate a thin silver layer on polyethylene terephthalate (PET) film without the use of toxic chemicals, high voltages, or an expensive vacuum apparatus. The developed film is applied to electromagnetic interference (EMI) shielding. After repeatedly depositing a silver layer through a plasma reduction reaction on PET, we can successfully fabricate a uniformly deposited thin silver layer. It was found that both the particle size and film thickness of thin silver layers fabricated at different AgNO3 concentrations increase with an increase in the concentration of AgNO3. However, the roughness of the thin silver layer decreases when increasing the concentration of AgNO3 from 100 to 500 mM, and the roughness increases with a further increase in the concentration of AgNO3. The EMI shielding effectiveness (SE) of the film is measured in the frequency range of 0.045 to 1 GHz. As a result of optimizing the electrical conductivity by measuring sheet resistance of the thin silver layer, the film fabricated from 500 mM AgNO3 exhibits the highest EMI SE among all fabricated films. The maximum values of the EMI SE are 60.490 dB at 0.1 GHz and 54.721 dB at 1.0 GHz with minimum sheet resistance of 0.244 Ω/□. Given that the proposed strategy is simple and effective, it is promising for fabricating various low-cost metal films with high EMI SE.

Comparison of reproduce signal and noise of conventional and keepered CoCrTa/Cr thin film media

NASA Astrophysics Data System (ADS)

Sin, Kyusik; Ding, Juren; Glijer, Pawel; Sivertsen, John M.; Judy, Jack H.; Zhu, Jian-Gang

1994-05-01

We studied keepered high coercivity CoCrTa/Cr thin film media with a Cr isolation layer between the CoCrTa storage and an overcoating of an isotropic NiFe soft magnetic layer. The influence of the thickness of the NiFe and Cr layers, and the effects of head bias current on the signal output and noise, were studied using a thin film head. The reproduced signal increased by 7.3 dB, but the signal-to-noise ratio decreased by 4 dB at a linear density of 2100 fr/mm (53.3 kfr/in.) with a 1000 Å thick NiFe keeper layer. The medium noise increased with increasing NiFe thickness and the signal output decreased with decreasing Cr thickness. A low output signal obtained with very thin Cr may be due to magnetic interactions between the keeper layer and magnetic media layer. It is observed that signal distortion and timing asymmetry of the output signals depend on the thickness of the keeper layer and the head bias current. The signal distortion increased and the timing asymmetry decreased as the head bias current was increased. These results may be associated with different permeability of the keeper under the poles of the thin film head due to the superposition of head bias and bit fields.

Multiple-layered effective medium approximation approach to modeling environmental effects on alumina passivated highly porous silicon nanostructured thin films measured by in-situ Mueller matrix ellipsometry

NASA Astrophysics Data System (ADS)

Mock, Alyssa; Carlson, Timothy; VanDerslice, Jeremy; Mohrmann, Joel; Woollam, John A.; Schubert, Eva; Schubert, Mathias

2017-11-01

Optical changes in alumina passivated highly porous silicon slanted columnar thin films during controlled exposure to toluene vapor are reported. Electron-beam evaporation glancing angle deposition and subsequent atomic layer deposition are utilized to deposit alumina passivated nanostructured porous silicon thin films. In-situ Mueller matrix generalized spectroscopic ellipsometry in an environmental cell is then used to determine changes in optical properties of the nanostructured thin films by inspection of individual Mueller matrix elements, each of which exhibit sensitivity to adsorption. The use of a multiple-layered effective medium approximation model allows for accurate description of the inhomogeneous nature of toluene adsorption onto alumina passivated highly porous silicon slanted columnar thin films.

Effect of Selectively Etched Ferroelectric Thin-Film Layer on the Performance of a Tunable Bandpass Filter

NASA Technical Reports Server (NTRS)

Subramanyam, Guru; Vignesparamoorthy, Sivaruban; Mueller, Carl; VanKeuls, Fred; Warner, Joseph; Miranda, Felix A.

2001-01-01

The main purpose of this work is to study the effect of a selectively etched ferroelectric thin film layer on the performance of an electrically tunable filter. An X-band tunable filter was designed, fabricated and tested on a selectively etched Barium Strontium Titanate (BSTO) ferroelectric thin film layer. Tunable filters with varying lengths of BSTO thin-film in the input and output coupling gaps were modeled, as well as experimentally tested. Experimental results showed that filters with coupling gaps partially filled with BSTO maintained frequency tunability and improved the insertion loss by approx. 2dB. To the best of our knowledge, these results represent the first experimental demonstration of the advantages of selective etching in the performance of thin film ferroelectric-based tunable microwave components.

Surface layer formation of LiCoO2 thin film electrodes in non-aqueous electrolyte containing lithium bis(oxalate)borate

NASA Astrophysics Data System (ADS)

Matsui, Masaki; Dokko, Kaoru; Akita, Yasuhiro; Munakata, Hirokazu; Kanamura, Kiyoshi

2012-07-01

Surface layer formation processes on a LiCoO2 thin film electrode in a non-aqueous electrolyte containing lithium bis(oxalate)borate (LiBOB) were investigated using in situ FTIR spectroscopy and X-ray photoelectron spectroscopy (XPS). The in situ FTIR spectra of the electrolyte solution containing LiBOB showed that the adsorption of BOB anions on the electrode surface occurred during the charge process of the LiCoO2 thin film electrode above 4.0 V. XPS analysis for the LiCoO2 thin film electrode charged in an electrolyte containing LiBOB suggested that the adsorbed BOB anions on the electrode surface prevent the continuous decomposition of hexafluorophosphate (PF6) anions resulting in the formation of a very thin surface layer containing organic species, while the LiCoO2 charged in a LiPF6 solution had a relatively thick surface layer containing organic species and inorganic species.

Nanofiber based triple layer hydro-philic/-phobic membrane - a solution for pore wetting in membrane distillation

PubMed Central

Prince, J. A.; Rana, D.; Matsuura, T.; Ayyanar, N.; Shanmugasundaram, T. S.; Singh, G.

2014-01-01

The innovative design and synthesis of nanofiber based hydro-philic/phobic membranes with a thin hydro-phobic nanofiber layer on the top and a thin hydrophilic nanofiber layer on the bottom of the conventional casted micro-porous layer which opens up a solution for membrane pore wetting and improves the pure water flux in membrane distillation. PMID:25377488

Burning Graphene Layer-by-Layer

PubMed Central

Ermakov, Victor A.; Alaferdov, Andrei V.; Vaz, Alfredo R.; Perim, Eric; Autreto, Pedro A. S.; Paupitz, Ricardo; Galvao, Douglas S.; Moshkalev, Stanislav A.

2015-01-01

Graphene, in single layer or multi-layer forms, holds great promise for future electronics and high-temperature applications. Resistance to oxidation, an important property for high-temperature applications, has not yet been extensively investigated. Controlled thinning of multi-layer graphene (MLG), e.g., by plasma or laser processing is another challenge, since the existing methods produce non-uniform thinning or introduce undesirable defects in the basal plane. We report here that heating to extremely high temperatures (exceeding 2000 K) and controllable layer-by-layer burning (thinning) can be achieved by low-power laser processing of suspended high-quality MLG in air in “cold-wall” reactor configuration. In contrast, localized laser heating of supported samples results in non-uniform graphene burning at much higher rates. Fully atomistic molecular dynamics simulations were also performed to reveal details of oxidation mechanisms leading to uniform layer-by-layer graphene gasification. The extraordinary resistance of MLG to oxidation paves the way to novel high-temperature applications as continuum light source or scaffolding material. PMID:26100466

Amino Acid Analyses of Acid Hydrolysates in Desert Varnish

NASA Technical Reports Server (NTRS)

Perry, Randall S.; Staley, James T.; Dworkin, Jason P.; Engel, Mike

2001-01-01

There has long been a debate as to whether rock varnish deposits are microbially mediated or are deposited by inorganic processes. Varnished rocks are found throughout the world primarily in arid and semi-arid regions. The varnish coats are typically up to 200 microns thick and are composed of clays and alternating layers enriched in manganese and iron oxides. The individual layers range in thickness from 1 micron to greater than 10 microns and may continue laterally for more than a 100 microns. Overlapping botryoidal structures are visible in thin section and scanning electron micrographs. The coatings also include small amounts of organic mater and detrital grains. Amino-acid hydrolysates offer a means of assessing the organic composition of rock varnish collected from the Sonoran Desert, near Phoenix, AZ. Chromatographic analyses of hydrolysates from powdered samples of rock varnish suggest that the interior of rock varnish is relatively enriched in amino acids and specifically in d-alanine and glutamic acid. Peptidoglycan (murein) is the main structural component of gram-positive bacterial cell walls. The d-enantiomer of alanine and glutamic acid are specific to peptidoglycan and are consequently an indicator for the presence of bacteria. D-alanine is also found in teichoic acid which is only found in gram-positive bacteria. Several researchers have cultured bacteria from the surface of rock varnish and most have been gram-positive, suggesting that gram-positive bacteria are intimately associated with varnish coatings and may play a role in the formation of varnish coatings.

Direct resolution and quantitative analysis of flurbiprofen enantiomers using microcrystalline cellulose triacetate plates: applications to the enantiomeric purity control and optical isomer determination in widely consumed drugs.

PubMed

Del Bubba, M; Checchini, L; Ciofi, L; Furlanetto, S; Lepri, L

2014-01-01

Flurbiprofen enantiomers have very different pharmacological properties, since the (S)-(+) form has a much higher anti-inflammatory activity than the (R)-(-) isomer, the latter being responsible for very undesirable side effects, such as gastrointestinal irritation. Based on the different biological properties of flurbiprofen enantiomers, the development of chiral chromatographic methods for the control of the enantiomeric purity is a very important topic. In this study the separation of flurbiprofen enantiomers was achieved using for the first time noncommercial MCTA layers with polyvinyl alcohol as binder, which gives to these plates a mechanical stability equivalent to that of marketed ones. Baseline resolution (α = 1.31; RS = 2.0) was obtained with ethanol-acetic acid solution (pH 3.0 ± 0.1; 60:40, v/v) as eluent and a migration distance of about 14.5 cm. Under these experimental conditions, the thin-layer chromatography determination of the enantiomeric purity of the pharmacologically active (S)-(+)-flurbiprofen in the presence of 1% of the undesired (R)-(-) form was demonstrated. Moreover, the quantitative analysis of flurbiprofen enantiomers was achieved, obtaining quantification limits and detection limits of 50 and 25 ng of each enantiomer applied to the plate, respectively. The method was succesfully applied to the enantiomer determination in widely consumed drugs, obtaining results consistent with the flurbiprofen content declared in the drug facts. Copyright © 2013 John Wiley & Sons, Ltd.

Polymer mediated layer-by-layer assembly of different shaped gold nanoparticles.

PubMed

Budy, Stephen M; Hamilton, Desmond J; Cai, Yuheng; Knowles, Michelle K; Reed, Scott M

2017-02-01

Gold nanoparticles (GNPs) have a wide range of properties with potential applications in electronics, optics, catalysis, and sensing. In order to demonstrate that dense, stable, and portable samples could be created for these applications, multiple layers of GNPs were assembled via drop casting on glass substrates by layer-by-layer (LBL) techniques. Two cationic polyelectrolytes, poly(diallyldimethylammonium chloride) and polyethyleneimine, one anionic polyelectrolyte, poly(sodium 4-styrene sulfonate), and one neutral polymer, polyvinylpyrrolidone, were combined with four different shapes of GNPs (spherical, rod, triangular prismatic, and octahedral) to prepare thin films. A subset of these polymer nanoparticle combinations were assembled into thin films. Synthesized GNPs were characterized via dynamic light scattering, UV-vis spectroscopy, and transmission electron microscopy and the LBL thin films were characterized using UV-vis spectroscopy and atomic force microscopy. Sensing applications of the nanoparticles in solution and thin films were tested by monitoring the localized surface plasmon resonance of the GNPs. LBL thin films were prepared ranging from 25 to 100 layers with optical densities at plasmon from 0.5 to 3.0. Sensitivity in solutions ranged from 14 to 1002nm/refractive index units (RIU) and films ranged from 18.8 to 135.1nm/RIU suggesting reduced access to the GNPs within the films. Copyright © 2016 Elsevier Inc. All rights reserved.

Stepwise crystallization and the layered distribution in crystallization kinetics of ultra-thin poly(ethylene terephthalate) film

NASA Astrophysics Data System (ADS)

Zuo, Biao; Xu, Jianquan; Sun, Shuzheng; Liu, Yue; Yang, Juping; Zhang, Li; Wang, Xinping

2016-06-01

Crystallization is an important property of polymeric materials. In conventional viewpoint, the transformation of disordered chains into crystals is usually a spatially homogeneous process (i.e., it occurs simultaneously throughout the sample), that is, the crystallization rate at each local position within the sample is almost the same. Here, we show that crystallization of ultra-thin poly(ethylene terephthalate) (PET) films can occur in the heterogeneous way, exhibiting a stepwise crystallization process. We found that the layered distribution of glass transition dynamics of thin film modifies the corresponding crystallization behavior, giving rise to the layered distribution of the crystallization kinetics of PET films, with an 11-nm-thick surface layer having faster crystallization rate and the underlying layer showing bulk-like behavior. The layered distribution in crystallization kinetics results in a particular stepwise crystallization behavior during heating the sample, with the two cold-crystallization temperatures separated by up to 20 K. Meanwhile, interfacial interaction is crucial for the occurrence of the heterogeneous crystallization, as the thin film crystallizes simultaneously if the interfacial interaction is relatively strong. We anticipate that this mechanism of stepwise crystallization of thin polymeric films will allow new insight into the chain organization in confined environments and permit independent manipulation of localized properties of nanomaterials.

Stepwise crystallization and the layered distribution in crystallization kinetics of ultra-thin poly(ethylene terephthalate) film

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zuo, Biao, E-mail: chemizuo@zstu.edu.cn, E-mail: wxinping@yahoo.com; Xu, Jianquan; Sun, Shuzheng

2016-06-21

Crystallization is an important property of polymeric materials. In conventional viewpoint, the transformation of disordered chains into crystals is usually a spatially homogeneous process (i.e., it occurs simultaneously throughout the sample), that is, the crystallization rate at each local position within the sample is almost the same. Here, we show that crystallization of ultra-thin poly(ethylene terephthalate) (PET) films can occur in the heterogeneous way, exhibiting a stepwise crystallization process. We found that the layered distribution of glass transition dynamics of thin film modifies the corresponding crystallization behavior, giving rise to the layered distribution of the crystallization kinetics of PET films,more » with an 11-nm-thick surface layer having faster crystallization rate and the underlying layer showing bulk-like behavior. The layered distribution in crystallization kinetics results in a particular stepwise crystallization behavior during heating the sample, with the two cold-crystallization temperatures separated by up to 20 K. Meanwhile, interfacial interaction is crucial for the occurrence of the heterogeneous crystallization, as the thin film crystallizes simultaneously if the interfacial interaction is relatively strong. We anticipate that this mechanism of stepwise crystallization of thin polymeric films will allow new insight into the chain organization in confined environments and permit independent manipulation of localized properties of nanomaterials.« less

Approximate transient and long time limit solutions for the band broadening induced by the thin sidewall-layer in liquid chromatography columns.

PubMed

Broeckhoven, Ken; Desmet, Gert

2007-11-16

Using a combination of both analytical and numerical techniques, approximate analytical expressions have been established for the transient and long time limit band broadening, originating from the presence of a thin disturbed sidewall layer in liquid chromatography columns, including packed, monolithic as well as microfabricated columns. The established expressions can be used to compare the importance of a thin disturbed sidewall layer with that of other radial heterogeneity effects (such as transcolumn packing density variations due to the relief of packing stresses). The expressions are independent of the actual velocity profile inside the layer as long as the disturbed sidewall layer occupies less than 2.5% of the column width.

Enhancement of absorption and color contrast in ultra-thin highly absorbing optical coatings

NASA Astrophysics Data System (ADS)

Kats, Mikhail A.; Byrnes, Steven J.; Blanchard, Romain; Kolle, Mathias; Genevet, Patrice; Aizenberg, Joanna; Capasso, Federico

2013-09-01

Recently a new class of optical interference coatings was introduced which comprises ultra-thin, highly absorbing dielectric layers on metal substrates. We show that these lossy coatings can be augmented by an additional transparent subwavelength layer. We fabricated a sample comprising a gold substrate, an ultra-thin film of germanium with a thickness gradient, and several alumina films. The experimental reflectivity spectra showed that the additional alumina layer increases the color range that can be obtained, in agreement with calculations. More generally, this transparent layer can be used to enhance optical absorption, protect against erosion, or as a transparent electrode for optoelectronic devices.

High Performance 50 nm InAlAs/In0.75GaAs Metamorphic High Electron Mobility Transistors with Si3N4 Passivation on Thin InGaAs Layer

NASA Astrophysics Data System (ADS)

Yeon, Seongjin; Seo, Kwangseok

2008-04-01

We fabricated 50 nm InAlAs/InGaAs metamorphic high electron mobility transistors (HEMTs) with a very thin barrier. Through the reduction of the gate-channel distance (dGC) in the epitaxial structure, a channel aspect ratio (ARC) of over three was achieved when Lg was 50 nm. We inserted a thin InGaAs layer as a protective layer, and tested various gate structures to reduce surface problems induced by barrier shrinkage and to optimize the device characteristics. Through the optimization of the gate structure with the thin InGaAs layer, the fabricated 50 nm metamorphic HEMT exhibited high DC and RF characteristics, Gm of 1.5 S/mm, and fT of 490 GHz.

Frontally eluted components procedure with thin layer chromatography as a mode of sample preparation for high performance liquid chromatography quantitation of acetaminophen in biological matrix.

PubMed

Klimek-Turek, A; Sikora, M; Rybicki, M; Dzido, T H

2016-03-04

A new concept of using thin-layer chromatography to sample preparation for the quantitative determination of solute/s followed by instrumental techniques is presented Thin-layer chromatography (TLC) is used to completely separate acetaminophen and its internal standard from other components (matrix) and to form a single spot/zone containing them at the solvent front position (after the final stage of the thin-layer chromatogram development). The location of the analytes and internal standard in the solvent front zone allows their easy extraction followed by quantitation by HPLC. The exctraction procedure of the solute/s and internal standard can proceed from whole solute frontal zone or its part without lowering in accuracy of quantitative analysis. Copyright © 2016 Elsevier B.V. All rights reserved.

Thin layer drying of cassava starch using continuous vibrated fluidized bed dryer

NASA Astrophysics Data System (ADS)

Suherman, Trisnaningtyas, Rona

2015-12-01

This paper present the experimental work and thin layer modelling of cassava starch drying in continuous vibrated fluidized bed dryer. The experimental data was used to validate nine thin layer models of drying curve. Cassava starch with 0.21 initial moisture content was dried in different air drying temperature (50°C, 55°C, 60°C, 65°C, 70°C), different weir height in bed (0 and 1 cm), and different solid feed flow (10 and 30 gr.minute-1). The result showed air dryer temperature has a significant effect on drying curve, while the weir height and solid flow rate are slightly. Based on value of R2, χ2, and RMSE, Page Model is the most accurate simulation for thin layer drying model of cassava starch.

Fabrication of nanocrystal ink based superstrate-type CuInS₂ thin film solar cells.

PubMed

Cho, Jin Woo; Park, Se Jin; Kim, Woong; Min, Byoung Koun

2012-07-05

A CuInS₂ (CIS) nanocrystal ink was applied to thin film solar cell devices with superstrate-type configuration. Monodispersed CIS nanocrystals were synthesized by a colloidal synthetic route and re-dispersed in toluene to form an ink. A spray method was used to coat CIS films onto conducting glass substrates. Prior to CIS film deposition, TiO₂ and CdS thin films were also prepared as a blocking layer and a buffer layer, respectively. We found that both a TiO₂ blocking layer and a CdS buffer layer are necessary to generate photoresponses in superstrate-type devices. The best power conversion efficiency (∼1.45%) was achieved by the CIS superstrate-type thin film solar cell device with 200 and 100 nm thick TiO₂ and CdS films, respectively.

Synthesis and Characterization of Hydrophobic Silica Thin Layer Derived from Methyltrimethoxysilane (MTMS)

NASA Astrophysics Data System (ADS)

Darmawan, Adi; Utari, Riyadini; Eka Saputra, Riza; Suhartana; Astuti, Yayuk

2018-01-01

This study investigated the synthesis and characterization of MTMS hydrophobic silica prepared by sol-gel method. In principle, silica xerogels and silica thin layer were obtained by reacting MTMS in ethanol solvent in some pH variations. The MTMS solution was used to modify the surface of the ceramic plate by dipcoating method to further be calcined at two different temperatures of 350°C and 500°C. The silica xerogels were analysed by FTIR, TGA-DSC and GSA to determine functional group characteristics, thermal properties and pore morphology respectively. Meanwhile, the silica thin layers were analysed their hydrophobic properties using water contact angle measurement and surface roughness determination using SEM. The results showed that the higher the pH used in the MTMS solution, the higher the resulting contact angle. The highest contact angle was obtained at pH 8.12 which reached 94.7° and 79.5° for silica thin layer calcined at 350°C and 500°C, respectively. The TGA results indicated that the methyl group survived up to 400°C and disappeared at 500°C which had implications on silica thin layer hydrophobic nature. GSA result exhibited that the silica xerogel had a close structure with a very low pore volume. While the SEM-EDX results displayed that the silica thin layer prepared at acidic pH had smoother surface morphology and became rough when prepared at an alkaline pH.

Composite lamination method

NASA Technical Reports Server (NTRS)

Dickerson, G. E. (Inventor)

1977-01-01

A process was developed for preparing relatively thick composite laminate structure wherein thin layers of prepreg tapes are assembled, these thin layers are cut into strips that are partially cured, and stacked into the desired thickness with uncured prepreg disposed between each layer of strips. The formed laminate is finally cured and thereafter machined to the desired final dimensions.

A Step toward High-Energy Silicon-Based Thin Film Lithium Ion Batteries.

PubMed

Reyes Jiménez, Antonia; Klöpsch, Richard; Wagner, Ralf; Rodehorst, Uta C; Kolek, Martin; Nölle, Roman; Winter, Martin; Placke, Tobias

2017-05-23

The next generation of lithium ion batteries (LIBs) with increased energy density for large-scale applications, such as electric mobility, and also for small electronic devices, such as microbatteries and on-chip batteries, requires advanced electrode active materials with enhanced specific and volumetric capacities. In this regard, silicon as anode material has attracted much attention due to its high specific capacity. However, the enormous volume changes during lithiation/delithiation are still a main obstacle avoiding the broad commercial use of Si-based electrodes. In this work, Si-based thin film electrodes, prepared by magnetron sputtering, are studied. Herein, we present a sophisticated surface design and electrode structure modification by amorphous carbon layers to increase the mechanical integrity and, thus, the electrochemical performance. Therefore, the influence of amorphous C thin film layers, either deposited on top (C/Si) or incorporated between the amorphous Si thin film layers (Si/C/Si), was characterized according to their physical and electrochemical properties. The thin film electrodes were thoroughly studied by means of electrochemical impedance spectroscopy, Raman spectroscopy, X-ray photoelectron spectroscopy, and atomic force microscopy. We can show that the silicon thin film electrodes with an amorphous C layer showed a remarkably improved electrochemical performance in terms of capacity retention and Coulombic efficiency. The C layer is able to mitigate the mechanical stress during lithiation of the Si thin film by buffering the volume changes and to reduce the loss of active lithium during solid electrolyte interphase formation and cycling.

Effects of different wetting layers on the growth of smooth ultra-thin silver thin films

NASA Astrophysics Data System (ADS)

Ni, Chuan; Shah, Piyush; Sarangan, Andrew M.

2014-09-01

Ultrathin silver films (thickness below 10 nm) are of great interest as optical coatings on windows and plasmonic devices. However, producing these films has been a continuing challenge because of their tendency to form clusters or islands rather than smooth contiguous thin films. In this work we have studied the effect of Cu, Ge and ZnS as wetting layers (1.0 nm) to achieve ultrasmooth thin silver films. The silver films (5 nm) were grown by RF sputter deposition on silicon and glass substrates using a few monolayers of the different wetting materials. SEM imaging was used to characterize the surface properties such as island formation and roughness. Also the optical properties were measured to identify the optical impact of the different wetting layers. Finally, a multi-layer silver based structure is designed and fabricated, and its performance is evaluated. The comparison between the samples with different wetting layers show that the designs with wetting layers which have similar optical properties to silver produce the best overall performance. In the absence of a wetting layer, the measured optical spectra show a significant departure from the model predictions, which we attribute primarily to the formation of clusters.

Durable high strength cement concrete topping for asphalt roads

NASA Astrophysics Data System (ADS)

Vyrozhemskyi, Valerii; Krayushkina, Kateryna; Bidnenko, Nataliia

2017-09-01

Work on improving riding qualities of pavements by means of placing a thin cement layer with high roughness and strength properties on the existing asphalt pavement were conducted in Ukraine for the first time. Such pavement is called HPCM (High Performance Cementitious Material). This is a high-strength thin cement-layer pavement of 8-9 mm thickness reinforced with metal or polymer fiber of less than 5 mm length. Increased grip properties are caused by placement of stone material of 3-5 mm fraction on the concrete surface. As a result of the research, the preparation and placement technology of high-strength cement thin-layer pavement reinforced with fiber was developed to improve friction properties of existing asphalt pavements which ensures their roughness and durability. It must be emphasized that HPCM is a fundamentally new type of thin-layer pavement in which a rigid layer of 10 mm thickness is placed on a non-rigid base thereby improving riding qualities of asphalt pavement at any season of a year.

INVESTIGATION OF A MIXTURE CONTAINING ALPRAZOLAM, CODEINE AND PARACETAMOL USING THIN-LAYER AND HIGH PERFORMANCE LIQUID CHROMATOGRAPHY METHODS.

PubMed

Ciegis, Paulius; Zevzikovas, Andrejus; Zevzikoviene, Augusta; Nenortiene, Palma; Kazlauskiene, Daiva

2016-01-01

The increasing drug consumption in Lithuania and all over the world makes us think about the negative consequences - the risk of toxicity. Fast and accurate identification of material that caused the poisoning reduces the probability in death cases and makes easier to determine the main cause of death. The results have shown that the most appropriate systems of solvents for qualitative analysis by TLC method of the mixture consisting of alprazolam, codeine and paracetanol are: system "D" (trichloromethane : acetone : conc. ammonia = 55 : 40 : 5 (v/v/v)) and system "F" (trichloromethane : diethyl ether: isobutanol : conc. ammonia = 50 : 30 : 15 : 5 (v/v/v/v)). For qualitative analysis of the mixture consisting of alprazolam, codeine and paracetamol by HPLC method the chromatographic column ACE C18 (25 cm x 4.6 mm x 5 µm), gradient elution mode (mixture of 3% acetic acid and methanol and the flow rate 1 mL/min have been used. The injection volume was 10 pL. Photodiode array detector (210 - 240 nm range) has been used. UV absorption spectra of materials measured using photodiode array detector have been identical to those presented in the scientific literature.

Detection of glucose oxidation products in chilled fresh beef undergoing spoilage.

PubMed Central

Farber, J M; Idziak, E S

1982-01-01

The fate of nutrients during storage of longissimus dorsi muscle at 4 degrees C was examined. Glucose concentrations in meat were shown to decrease concomitantly with an approximately fourfold increase in the activity of glucose dehydrogenase. Gluconate concentrations in meat were determined by an enzyme assay and shown to increase from 2.1 to 40.6 microgram/g upon storage of the meat from day 0 to day 6. At day 12, gluconate concentrations had decreased to 5.8 microgram/g. Dark firm dry meat, which contains little or no glucose, did not exhibit the same rise and fall in gluconate concentration. Thin-layer chromatographic analysis confirmed the presence of 2-ketogluconate in 6- and 12-day-old longissimus dorsi muscle that had been stored at 4 degrees C. Gluconate concentrations in irradiated sterile meat inoculated with Pseudomonas fluorescens increased from 4.2 to 77.8 microgram/g during the first 6 days of storage at 4 degrees C. Therefore, glucose in meat stored at 4 degrees C appeared to be converted to gluconate, 2-ketogluconate, or both extracellularly by one of the main meat spoilage organisms, most likely the pseudomonads. PMID:7137997

Influence of an experimental herbicide on soil nitrogen-fixing bacteria and other microorganisms

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nelson, L.M. Jr.; Hedrick, H.G.

Influence of an experimental herbicide on two isolates of soil nitrogen-fixing bacteria Rhizobium japonicum 3I1b110 and Azotobacter vinelandii ATCC 12837, was determined using a bioresponse assay, thin-layer chromatographic analysis, and changes in viable cells on the herbicide as the sole source of organic carbon. Seven bacterial and nine fungus isolates were also found by a soil enrichment technique to show utilization of the herbicide. A. vinelandii showed stimulation of growth in the first 4 days of exposure on the herbicide at 1,000 ppM. The herbicide then became toxic or was metabolized into toxic by-products. R. japonicum showed utilization of themore » herbicide by changes in growth rate as influenced by the inoculum concentration, the thoroughness of inoculum washing, and the concentration of herbicide. Using TLC assay techniques, the herbicide was found to be depleted in laboratory experiments by R. japonicum following 10 days of growth, without detectable nonmetabolic by-products. These findings suggested that the addition of the experimental herbicide to soils planted with bean crops could possibly influence the metabolic activity of R. japonicum as a symbiotic nitrogen-fixing bacterium. 5 figures, 1 table.« less

Preliminary pharmacognostic screening of Achyranthes coynei stem.

PubMed

Upadhya, Vinayak; Ankad, Gireesh M; Pai, Sandeep R; Hegde, Shruti V; Hegde, Harsha V

2015-01-01

Achyranthes coynei is a rare, endemic perennial shrub reported from Karnataka and Maharashtra states of India. The plant is used to treat various disorders by folk healers and was proven to have antimicrobial and antioxidant properties. The present study was undertaken to evaluate microscopic and macroscopic characters of A. coynei stem, along with its physicochemical parameters. ProgRes(®) CapturePro and Microsoft Excel were used for statistical analysis. Perennial, shrubby nature and woody stem were the distinguishing morphological characters observed. Transverse section (TS) illustrated quadrangular outline of the stem and showed the presence of two types of trichomes on the thick-walled epidermis. TS also showed number of rosette calcium oxalates crystals; prismatic and microsphenoid crystals; conjoint, collateral open secondary vascular bundles; and two amphixylic medullary bundles in the pith. Ash and extractive values, micro and macro elements and nutritive factors were estimated in the present study. The presence of alkaloids, saponins and triterpenoids were observed in preliminary phytochemical screening. High-performance thin layer chromatographic analysis yielded different bands and also indicated the presence of oleanolic acid. The studied parameters for A. coynei stem will be useful for identification and authentication of the plant material.

Purification and Biochemical and Kinetic Properties of an Endo-Polygalacturonase from the Industrial Fungus Aspergillus sojae.

PubMed

Fratebianchi, Dante; Cavello, Ivana Alejandra; Cavalitto, Sebastián Fernando

2017-01-01

An endo-polygalacturonase secreted by Aspergillus sojae was characterized after being purified to homogeneity from submerged cultures with orange peel as the sole carbon source by gel filtration and ion-exchange chromatographies. According to SDS-PAGE and analytical isoelectric focusing analyses, the enzyme presents a molecular weight of 47 kDa and pI value of 4.2. This enzyme exhibits considerable stability under highly acidic to neutral conditions (pH 1.5-6.5) and presents a half-life of 2 h at 50°C. Besides its activity towards pectin and polygalacturonic acid, the enzyme displays pectin-releasing activity, acting best in a pH range of 3.3-5.0. Thin-layer chromatographic analysis revealed that tri-galacturonate is the main enzymatic end product of polygalacturonic acid hydrolysis, indicating that it is an endo-polygalacturonase. The enzyme exhibits Michaelis-Menten kinetics, with KM and VMAX values of 0.134 mg/mL and 9.6 µmol/mg/min, respectively, and remained stable and active in the presence of SO2, ethanol, and various cations assayed except Hg2+. © 2017 S. Karger AG, Basel.

Ameliorative effects of stinging nettle (Urtica dioica) on testosterone-induced prostatic hyperplasia in rats.

PubMed

Nahata, A; Dixit, V K

2012-05-01

The present study investigated the effects of stinging nettle (Urtica dioica L.) (UD) on benign prostatic hyperplasia (BPH) induced by testosterone. In vitro studies were conducted to assess the 5α-reductase inhibitory potential of UD. Two biochemical markers viz., β-sitosterol and scopoletin, were isolated and characterised in the extracts utilising High-performance thin layer chromatographic, FTIR, NMR and overlain UV spectral studies. Hyperplasia was induced in rats by subcutaneous administration of testosterone (3 mg kg(-1) s.c.) for 28 days in all the groups except the vehicle-treated group. Simultaneous administration of petroleum ether and ethanolic extracts (10, 20 and 50 mg kg(-1) p.o.) and isolated β-sitosterol (10 and 20 mg kg(-1) p.o.) was undertaken. Finasteride was used as a positive control (1 mg kg(-1) p.o.). Measurement of prostate/body weight ratio, weekly urine output and serum testosterone levels, prostate-specific antigen levels (on day 28) and histological examinations carried out on prostates from each group led us to conclude that UD can be used as an effective drug for the management of BPH. © 2011 Blackwell Verlag GmbH.

Apigenin inhibits rat neurosteroidogenic 5α-reductase 1 and 3α-hydroxysteroid dehydrogenase.

PubMed

Wu, Ying; Li, Lili; Zhou, Songyi; Shen, Qiuxia; Lin, Han; Zhu, Qiqi; Sun, Jianliang; Ge, Ren-Shan

2017-11-01

Apigenin, a common flavonoid, has extensive pharmacological activities. Apigenin inhibits some steroid biosynthetic enzymes, suggesting that it may block neurosteroid synthesis. Neurosteroids play many important roles in neurological functions. The objective of the present study is to investigate effects of apigenin on neurosteroidogenic enzymes, 5α-reductase 1 (SRD5A1), 3α-hydroxysteroid dehydrogenase (AKR1C9), and retinol dehydrogenase 2 (RoDH2), in rats. SRD5A1, AKR1C9, and RoDH2 were expressed in COS-1 cells and the effects of apigenin on these enzymes and modes of action were explored using radiolabeled substrates and thin-layer chromatographic separation coupled with radiometry. Apigenin inhibited SRD5A1, AKR1C9, and RoDH2 activities with IC 50 values of 100, 0.891 ± 0.065, and >100 μM, respectively. Apigenin competitively inhibited rat AKR1C9 when its substrate 5α-dihydrotestosterone was used and uncompetitively inhibited the enzyme when cofactor NADPH was used. In conclusion, apigenin is a potent inhibitor of rat AKR1C9, thereby controlling the rate of neurosteroid biosynthesis. Copyright © 2017 Elsevier Ltd. All rights reserved.

Mycotoxins transmitted into beer from contaminated grains during brewing.

PubMed

Scott, P M

1996-01-01

Studies with aflatoxin B1, ochratoxin A, zearalenone, deoxynivalenol, and fumonisins B1 and B2 added at various stages of the brewing process show that these mycotoxins (or metabolites) may be transmitted from contaminated grains into beer. Citrinin does not survive the mashing step. Mycotoxins in beer could originate from the malted grain or from adjuncts. Although high incidences and concentrations of aflatoxins and zearalenone have been found in local beers brewed in Africa, aflatoxins have not been detected in European beers. Zearalenone and alpha- or beta-zearalenol (the metabolite likely to occur) have not been found in Canadian and European beers, except for one sample analyzed by thin-layer chromatography only. Ochratoxin A rarely has been detected at > 1 ng/mL in beer; liquid chromatographic methods with a 0.05-0.1 ng/mL detection limit, however, have shown moderately high incidences of trace levels. Deoxynivalenol, which survives the brewing process, has been found with high incidence in Canadian and European beers, with concentration of > 200 ng/mL reported in several German beers. Fumonisins B1 and B2 occur to a limited extent in beer.

Physicochemical properties of silica gel coated with a thin layer of polyaniline (PANI) and its application in non-suppressed ion chromatography.

PubMed

Sowa, Ireneusz; Kocjan, Ryszard; Wójciak-Kosior, Magdalena; Swieboda, Ryszard; Zajdel, Dominika; Hajnos, Mieczysław

2013-10-15

Physicochemical properties of a new sorbent and its potential application in non-suppressed ion chromatography (IC) have been investigated. The sorbent was obtained in a process of covering silica gel particles with a film of polyaniline (PANI). The properties of silica modified with polyaniline such as particle size, porosity, average quantity of polyaniline covering carrier and density of sorbent were determined. In our study the following methods were used: microscopic analysis, laser diffraction technique, combustion analysis, mercury porosimetry and helium pycnometry. Column with the newly obtained packing was used for the separation of inorganic anions. Optimized chromatographic system was successfully employed for analysis of iodide and bromide in selected pharmaceutical products (Bochnia salt and Iwonicz salt) applied in chronic respiratory disease. Analysis was carried out using 0.1M solution of HCl in mixture of methanol/water (50:50v/v) as a mobile phase; the flow rate was 0.3 mL min(-1), temperature was 24°C and λ=210 nm. Validation parameters such as correlation coefficient, RSD values, recovery, detection and quantification limits were found to be satisfactory. Copyright © 2013 Elsevier B.V. All rights reserved.

Separation and characterization of polycyclic aromatic hydrocarbons and alkylphenols in coal derived solvents

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hurtubise, R.J.; Allen, T.W.; Hussain, A.

1981-03-29

Dry-column chromatography with an aluminum oxide stationary phase and a n-hexane-ether (19:1) mobile phase was used to separate polycyclic aromatic hydrocarbons (PAH) by ring size. Prior to the dry-column chromatography step, the coal derived solvents were added to an acid treated silica gel column and eluted with chloroform. This step removed pyridine-type nitrogen heterocycles. After separation of the individual ring fractions, the fractions were further separated by either thin layer chromatography (TLC) or high performance liquid chromatography (HPLC). If TLC was used, then after separation fluorescence profiles of each PAH ring fraction distributed on 30%-acetylated cellulose chromatoplates were obtained withmore » a spectrodensitometer. Measurement of fluorescence peak heights gave an approximate measure of the amount of the 3-, 4-, 5-, and 6- ring PAH. For HPLC separation, the 3- and 4- ring PAH fractions obtained from the dry-column chromatography step were separated with a ..mu..-Bondapak C/sub 18/ column and methanol:water (65:35) mobile phase. The HPLC separated PAH were characterized by chromatographic correlation factors and corrected fluorescence excitation spectra. Alkylphenols were identified in coal recycle solvent sample following separation by HPLC.« less

Radioactive Phosphorylation of Alcohols to Monitor Biocatalytic Diels-Alder Reactions

PubMed Central

Nierth, Alexander; Jäschke, Andres

2011-01-01

Nature has efficiently adopted phosphorylation for numerous biological key processes, spanning from cell signaling to energy storage and transmission. For the bioorganic chemist the number of possible ways to attach a single phosphate for radioactive labeling is surprisingly small. Here we describe a very simple and fast one-pot synthesis to phosphorylate an alcohol with phosphoric acid using trichloroacetonitrile as activating agent. Using this procedure, we efficiently attached the radioactive phosphorus isotope 32P to an anthracene diene, which is a substrate for the Diels-Alderase ribozyme—an RNA sequence that catalyzes the eponymous reaction. We used the 32P-substrate for the measurement of RNA-catalyzed reaction kinetics of several dye-labeled ribozyme variants for which precise optical activity determination (UV/vis, fluorescence) failed due to interference of the attached dyes. The reaction kinetics were analyzed by thin-layer chromatographic separation of the 32P-labeled reaction components and densitometric analysis of the substrate and product radioactivities, thereby allowing iterative optimization of the dye positions for future single-molecule studies. The phosphorylation strategy with trichloroacetonitrile may be applicable for labeling numerous other compounds that contain alcoholic hydroxyl groups. PMID:21731729

Simultaneous quantification of stevioside and rebaudioside A in different stevia samples collected from the Indian subcontinent

PubMed Central

Chester, Karishma; Tamboli, Ennus T.; Singh, Mhaveer; Ahmad, Sayeed

2012-01-01

Background: A high performance thin layer chromatographic (HPTLC) method was developed for simultaneous estimation of stevioside and rebaudioside A in Stevia rebaudiana samples collected from different regions of Indian subcontinent. Materials and Methods: The separation was achieved by using acetone: ethyl acetate: water (5:4:1, v/v/v) as the solvent system on precoated silica gel 60 F254 TLC plates. The densitometric quantification of stevia glycosides was carried out at wavelength 360 nm in absorption mode after spraying with anisaldehyde sulphuric acid as detecting reagent. Results: The well resolved peaks for stevioside and rebaudioside A were observed at Rf values 0.31± 0.02 and 0.21± 0.02 respectively. The calibration curves were found linear with a wide range of concentration 100 - 2000 ng spot-1 with good correlation coefficient 0.996 and 0.991 for stevioside and rebaudioside A, respectively. Conclusions: The proposed method was validated as per the ICH (International Conferences on Harmonization) guidelines and found simple, sensitive, economic, reproducible, robust and accurate for quantitative analysis of stevia glycosides, which can be applied for quality control of stevia as well as to check. PMID:23248559

Uptake of Light Elements in Thin Metallic Films

NASA Astrophysics Data System (ADS)

Markwitz, Andreas; Waldschmidt, Mathias

Ion beam analysis was used to investigate the influence of substrate temperature on the inclusion of impurities during the deposition process of thin metallic single and double layers. Thin layers of gold and aluminium were deposited at different temperatures onto thin copper layers evaporated on silicon wafer substrates. The uptake of oxygen in the layers was measured using the highly sensitive non-resonant reaction 16O(d,p)170O at 920 keV. Nuclear reaction analysis was also used to probe for carbon and nitrogen with a limit of detection better than 20 ppm. Hydrogen depth profiles were measured using elastic recoil detection on the nanometer scale. Rutherford backscattering spectroscopy was used to determine the depth profiles of the metallic layers and to study diffusion processes. The combined ion beam analyses revealed an uptake of oxygen in the layers depending on the different metallic cap layers and the deposition temperature. Lowest oxygen values were measured for the Au/Cu layers, whereas the highest amount of oxygen was measured in Al/Cu layers deposited at 300°C. It was also found that with single copper layers produced at various temperatures, oxygen contamination occurred during the evaporation process and not afterwards, for example, as a consequence of the storage of the films under normal conditions for several days. Hydrogen, carbon, and nitrogen were found as impurities in the single and double layered metallic films, a finding that is in agreement with the measured oxidation behaviour of the metallic films.

Method of forming ultra thin film devices by vacuum arc vapor deposition

NASA Technical Reports Server (NTRS)

Schramm, Harry F. (Inventor)

2005-01-01

A method for providing an ultra thin electrical circuit integral with a portion of a surface of an object, including using a focal Vacuum Arc Vapor Deposition device having a chamber, a nozzle and a nozzle seal, depressing the nozzle seal against the portion of the object surface to create an airtight compartment in the chamber and depositing one or more ultra thin film layer(s) only on the portion of the surface of the object, the layers being of distinct patterns such that they form the circuit.

Non-destructive evaluation of nano-sized structure of thin film devices by using small angle neutron scattering.

PubMed

Shin, E J; Seong, B S; Choi, Y; Lee, J K

2011-01-01

Nano-sized multi-layers copper-doped SrZrO3, platinum (Pt) and silicon oxide (SiO2) on silicon substrates were prepared by dense plasma focus (DPF) device with the high purity copper anode tip and analyzed by using small angle neutron scattering (SANS) to establish a reliable method for the non-destructive evaluation of the under-layer structure. Thin film was well formed at the time-to-dip of 5 microsec with stable plasma of DPF. Several smooth intensity peaks were periodically observed when neutron beam penetrates the thin film with multi-layers perpendicularly. The platinum layer is dominant to intensity peaks, where the copper-doped SrZnO3 layer next to the platinum layer causes peak broadening. The silicon oxide layer has less effect on the SANS spectra due to its relative thick thickness. The SANS spectra shows thicknesses of platinum and copper-doped SrZnO3 layers as 53 and 25 nm, respectively, which are well agreement with microstructure observation.

Layer-by-layer deposition of nanostructured CsPbBr3 perovskite thin films

NASA Astrophysics Data System (ADS)

Reshetnikova, A. A.; Matyushkin, L. B.; Andronov, A. A.; Sokolov, V. S.; Aleksandrova, O. A.; Moshnikov, V. A.

2017-11-01

Layer-by-layer deposition of nanostructured perovskites cesium lead halide thin films is described. The method of deposition is based on alternate immersion of the substrate in the precursor solutions or colloidal solution of nanocrystals and methyl acetate/lead nitrate solution using the device for deposition of films by SILAR and dip-coating techniques. An example of obtaining a photosensitive structure based on nanostructures of ZnO nanowires and layers of CsBbBr3 nanocrystals is also shown.

Silicon superlattices. 2: Si-Ge heterostructures and MOS systems

NASA Technical Reports Server (NTRS)

Moriarty, J. A.

1983-01-01

Five main areas were examined: (1) the valence-and conduction-band-edge electronic structure of the thin layer ( 11 A) silicon-superlattice systems; (2) extension of thin-layer calculations to layers of thickness 11 A, where most potential experimental interest lies; (3) the electronic structure of thicker-layer (11 to 110 A) silicon superlattices; (4) preliminary calculations of impurity-scattering-limited electron mobility in the thicker-layer superlattices; and (5) production of the fine metal lines that would be required to produce on MOS superlattice.

Epitaxial thinning process

NASA Technical Reports Server (NTRS)

Siegel, C. M. (Inventor)

1984-01-01

A method is described for thinning an epitaxial layer of a wafer that is to be used in producing diodes having a specified breakdown voltage and which also facilitates the thinning process. Current is passed through the epitaxial layer, by connecting a current source between the substrate of the wafer and an electrolyte in which the wafer is immersed. When the wafer is initially immersed, the voltage across the wafer initially drops and then rises at a steep rate. When light is applied to the wafer the voltage drops, and when the light is interrupted the voltage rises again. These changes in voltage, each indicate the breakdown voltage of a Schottky diode that could be prepared from the wafer at that time. The epitaxial layer is thinned by continuing to apply current through the wafer while it is immersed and light is applied, to form an oxide film and when the oxide film is thick the wafer can then be cleaned of oxide and the testing and thinning continued. Uninterrupted thinning can be achieved by first forming an oxide film, and then using an electrolyte that dissolves the oxide about as fast as it is being formed, to limit the thickness of the oxide layer.

Electrochemical planarization

DOEpatents

Bernhardt, A.F.; Contolini, R.J.

1993-10-26

In a process for fabricating planarized thin film metal interconnects for integrated circuit structures, a planarized metal layer is etched back to the underlying dielectric layer by electropolishing, ion milling or other procedure. Electropolishing reduces processing time from hours to minutes and allows batch processing of multiple wafers. The etched back planarized thin film interconnect is flush with the dielectric layer. 12 figures.

Use of screenings to produce HMA mixtures

DOT National Transportation Integrated Search

2002-10-01

Thin-lift hot mix asphalt (HMA) layers are utilized in almost every maintenance and rehabilitation application. These mix types require smaller maximum particle sizes than most conventional HMA surface layers. Although the primary functions of thin-l...

[Ascending one-dimensional thin layer chromatography in specific blood diagnosis (author's transl)].

PubMed

Bernardelli, B; Masotti, G

1976-01-01

A brief review of the literature on chromatography in forensic haematology is followed by a report of the results obtained by using ascending one-dimensional thin layer chromatography in specific blood diagnosis.

Flat-lying semiconductor-insulator interfacial layer in DNTT thin films.

PubMed

Jung, Min-Cherl; Leyden, Matthew R; Nikiforov, Gueorgui O; Lee, Michael V; Lee, Han-Koo; Shin, Tae Joo; Takimiya, Kazuo; Qi, Yabing

2015-01-28

The molecular order of organic semiconductors at the gate dielectric is the most critical factor determining carrier mobility in thin film transistors since the conducting channel forms at the dielectric interface. Despite its fundamental importance, this semiconductor-insulator interface is not well understood, primarily because it is buried within the device. We fabricated dinaphtho[2,3-b:2',3'-f]thieno[3,2-b]thiophene (DNTT) thin film transistors by thermal evaporation in vacuum onto substrates held at different temperatures and systematically correlated the extracted charge mobility to the crystal grain size and crystal orientation. As a result, we identify a molecular layer of flat-lying DNTT molecules at the semiconductor-insulator interface. It is likely that such a layer might form in other material systems as well, and could be one of the factors reducing charge transport. Controlling this interfacial flat-lying layer may raise the ultimate possible device performance for thin film devices.

Bias of shear wave elasticity measurements in thin layer samples and a simple correction strategy.

PubMed

Mo, Jianqiang; Xu, Hao; Qiang, Bo; Giambini, Hugo; Kinnick, Randall; An, Kai-Nan; Chen, Shigao; Luo, Zongping

2016-01-01

Shear wave elastography (SWE) is an emerging technique for measuring biological tissue stiffness. However, the application of SWE in thin layer tissues is limited by bias due to the influence of geometry on measured shear wave speed. In this study, we investigated the bias of Young's modulus measured by SWE in thin layer gelatin-agar phantoms, and compared the result with finite element method and Lamb wave model simulation. The result indicated that the Young's modulus measured by SWE decreased continuously when the sample thickness decreased, and this effect was more significant for smaller thickness. We proposed a new empirical formula which can conveniently correct the bias without the need of using complicated mathematical modeling. In summary, we confirmed the nonlinear relation between thickness and Young's modulus measured by SWE in thin layer samples, and offered a simple and practical correction strategy which is convenient for clinicians to use.

AES study on the chemical composition of ferroelectric BaTiO3 thin films RF sputter-deposited on silicon

NASA Technical Reports Server (NTRS)

Dharmadhikari, V. S.; Grannemann, W. W.

1983-01-01

AES depth profiling data are presented for thin films of BaTiO3 deposited on silicon by RF sputtering. By profiling the sputtered BaTiO3/silicon structures, it was possible to study the chemical composition and the interface characteristics of thin films deposited on silicon at different substrate temperatures. All the films showed that external surface layers were present, up to a few tens of angstroms thick, the chemical composition of which differed from that of the main layer. The main layer had stable composition, whereas the intermediate film-substrate interface consisted of reduced TiO(2-x) oxides. The thickness of this intermediate layer was a function of substrate temperature. All the films showed an excess of barium at the interface. These results are important in the context of ferroelectric phenomena observed in BaTiO3 thin films.

Impact of bimetal electrodes on dielectric properties of TiO2 and Al-doped TiO2 films.

PubMed

Kim, Seong Keun; Han, Sora; Jeon, Woojin; Yoon, Jung Ho; Han, Jeong Hwan; Lee, Woongkyu; Hwang, Cheol Seong

2012-09-26

Rutile structured Al-doped TiO(2) (ATO) and TiO(2) films were grown on bimetal electrodes (thin Ru/thick TiN, Pt, and Ir) for high-performance capacitors. The work function of the top Ru layer decreased on TiN and increased on Pt and Ir when it was thinner than ~2 nm, suggesting that the lower metal within the electrodes influences the work function of the very thin Ru layer. The use of the lower electrode with a high work function for bottom electrode eventually improves the leakage current properties of the capacitor at a very thin Ru top layer (≤2 nm) because of the increased Schottky barrier height at the interface between the dielectric and the bottom electrode. The thin Ru layer was necessary to achieve the rutile structured ATO and TiO(2) dielectric films.

Fuel cell with interdigitated porous flow-field

DOEpatents

Wilson, Mahlon S.

1997-01-01

A polymer electrolyte membrane (PEM) fuel cell is formed with an improved system for distributing gaseous reactants to the membrane surface. A PEM fuel cell has an ionic transport membrane with opposed catalytic surfaces formed thereon and separates gaseous reactants that undergo reactions at the catalytic surfaces of the membrane. The fuel cell may also include a thin gas diffusion layer having first and second sides with a first side contacting at least one of the catalytic surfaces. A macroporous flow-field with interdigitated inlet and outlet reactant channels contacts the second side of the thin gas diffusion layer for distributing one of the gaseous reactants over the thin gas diffusion layer for transport to an adjacent one of the catalytic surfaces of the membrane. The porous flow field may be formed from a hydrophilic material and provides uniform support across the backside of the electrode assembly to facilitate the use of thin backing layers.

Fuel cell with interdigitated porous flow-field

DOEpatents

Wilson, M.S.

1997-06-24

A polymer electrolyte membrane (PEM) fuel cell is formed with an improved system for distributing gaseous reactants to the membrane surface. A PEM fuel cell has an ionic transport membrane with opposed catalytic surfaces formed thereon and separates gaseous reactants that undergo reactions at the catalytic surfaces of the membrane. The fuel cell may also include a thin gas diffusion layer having first and second sides with a first side contacting at least one of the catalytic surfaces. A macroporous flow-field with interdigitated inlet and outlet reactant channels contacts the second side of the thin gas diffusion layer for distributing one of the gaseous reactants over the thin gas diffusion layer for transport to an adjacent one of the catalytic surfaces of the membrane. The porous flow field may be formed from a hydrophilic material and provides uniform support across the backside of the electrode assembly to facilitate the use of thin backing layers. 9 figs.

Electrical contacts to thin layers of Bi2Sr2CaCu2O8+δ

NASA Astrophysics Data System (ADS)

Suzuki, Shota; Taniguchi, Hiroki; Kawakami, Tsukasa; Cosset-Cheneau, Maxen; Arakawa, Tomonori; Miyasaka, Shigeki; Tajima, Setsuko; Niimi, Yasuhiro; Kobayashi, Kensuke

2018-05-01

Thin layers of Bi2Sr2CaCu2O8+δ (Bi2212) were fabricated using the mechanical exfoliation technique. Good electrical contacts to the thin Bi2212 films with low contact resistance were realized by depositing Ag and Au electrodes onto the Bi2212 films and annealing them with an oxygen flow at 350 °C for 30 min. We observed cross-section images of the Bi2212 thin film device using a transmission electron microscope to characterize the diffusion of Ag and Au atoms into the Bi2212 thin film.

Precise Control of the Number of Layers of Graphene by Picosecond Laser Thinning.

PubMed

Lin, Zhe; Ye, Xiaohui; Han, Jinpeng; Chen, Qiao; Fan, Peixun; Zhang, Hongjun; Xie, Dan; Zhu, Hongwei; Zhong, Minlin

2015-06-26

The properties of graphene can vary as a function of the number of layers (NOL). Controlling the NOL in large area graphene is still challenging. In this work, we demonstrate a picosecond (ps) laser thinning removal of graphene layers from multi-layered graphene to obtain desired NOL when appropriate pulse threshold energy is adopted. The thinning process is conducted in atmosphere without any coating and it is applicable for graphene films on arbitrary substrates. This method provides many advantages such as one-step process, non-contact operation, substrate and environment-friendly, and patternable, which will enable its potential applications in the manufacturing of graphene-based electronic devices.

Precise Control of the Number of Layers of Graphene by Picosecond Laser Thinning

NASA Astrophysics Data System (ADS)

Lin, Zhe; Ye, Xiaohui; Han, Jinpeng; Chen, Qiao; Fan, Peixun; Zhang, Hongjun; Xie, Dan; Zhu, Hongwei; Zhong, Minlin

2015-06-01

The properties of graphene can vary as a function of the number of layers (NOL). Controlling the NOL in large area graphene is still challenging. In this work, we demonstrate a picosecond (ps) laser thinning removal of graphene layers from multi-layered graphene to obtain desired NOL when appropriate pulse threshold energy is adopted. The thinning process is conducted in atmosphere without any coating and it is applicable for graphene films on arbitrary substrates. This method provides many advantages such as one-step process, non-contact operation, substrate and environment-friendly, and patternable, which will enable its potential applications in the manufacturing of graphene-based electronic devices.

Thin-film limit formalism applied to surface defect absorption.

PubMed

Holovský, Jakub; Ballif, Christophe

2014-12-15

The thin-film limit is derived by a nonconventional approach and equations for transmittance, reflectance and absorptance are presented in highly versatile and accurate form. In the thin-film limit the optical properties do not depend on the absorption coefficient, thickness and refractive index individually, but only on their product. We show that this formalism is applicable to the problem of ultrathin defective layer e.g. on a top of a layer of amorphous silicon. We develop a new method of direct evaluation of the surface defective layer and the bulk defects. Applying this method to amorphous silicon on glass, we show that the surface defective layer differs from bulk amorphous silicon in terms of light soaking.

Fabrication of Organic Thin Film Transistors Using Layer-By-Layer Assembly (Preprint)

DTIC Science & Technology

2007-03-01

thin-film transistors ( TFTs ) have received considerable attention as a low- cost, light-weight, flexible alternative to traditional amorphous silicon...Previous studies have investigated the use of a number of materials for both the active layer and the gate dielectric in various TFT architectures. These...performance. Conjugated small molecules, such as pentacene, or polymers, such as poly(3- hexylthiophene), are commonly used as the active layer in organic TFT

Use of separate ZnTe interface layers to form ohmic contacts to p-CdTe films

DOEpatents

Gessert, T.A.

1999-06-01

A method of is disclosed improving electrical contact to a thin film of a p-type tellurium-containing II-VI semiconductor comprising: depositing a first undoped layer of ZnTe on a thin film of p-type tellurium containing II-VI semiconductor with material properties selected to limit the formation of potential barriers at the interface between the p-CdTe and the undoped layer, to a thickness sufficient to control diffusion of the metallic-doped ZnTe into the p-type tellurium-containing II-VI semiconductor, but thin enough to minimize affects of series resistance; depositing a second heavy doped p-type ZnTe layer to the first layer using an appropriate dopant; and depositing an appropriate metal onto the outer-most surface of the doped ZnTe layer for connecting an external electrical conductor to an ohmic contact. 11 figs.

High-performance a-IGZO thin-film transistor with conductive indium-tin-oxide buried layer

NASA Astrophysics Data System (ADS)

Ahn, Min-Ju; Cho, Won-Ju

2017-10-01

In this study, we fabricated top-contact top-gate (TCTG) structure of amorphous indium-gallium-zinc oxide (a-IGZO) thin-film transistors (TFTs) with a thin buried conductive indium-tin oxide (ITO) layer. The electrical performance of a-IGZO TFTs was improved by inserting an ITO buried layer under the IGZO channel. Also, the effect of the buried layer's length on the electrical characteristics of a-IGZO TFTs was investigated. The electrical performance of the transistors improved with increasing the buried layer's length: a large on/off current ratio of 1.1×107, a high field-effect mobility of 35.6 cm2/Vs, a small subthreshold slope of 116.1 mV/dec, and a low interface trap density of 4.2×1011 cm-2eV-1 were obtained. The buried layer a-IGZO TFTs exhibited enhanced transistor performance and excellent stability against the gate bias stress.

Thin Carbon Layers on Nanostructured Silicon-Properties and Applications

NASA Astrophysics Data System (ADS)

Angelescu, Anca; Kleps, Irina; Miu, Mihaela; Simion, Monica; Bragaru, Adina; Petrescu, Stefana; Paduraru, Crina; Raducanu, Aurelia

Thin carbon layers such as silicon carbide (SiC) and diamond like carbon (DLC) layers on silicon, or on nanostructured silicon substrats were obtained by different methods. This paper is a review of our results in the areas of carbon layer microfabrication technologies and their properties related to different microsystem apllications. So, silicon membranes using a-SiC or DLC layers as etching mask, as well as silicon carbide membranes using a combined porous silicon — DLC structure were fabricated for sensor applications. A detailed evaluation of the field emission (FE) properties of these films was done to demonstrate their capability to be used in field emission devices. Carbon thin layers on nanostructured silicon samples were also investigated with respect to the living cell adhesion on these structures. The experiments indicate that the cell attachment on the surface of carbon coatings can be controlled by deposition parameters during the technological process.

Use of separate ZnTe interface layers to form OHMIC contacts to p-CdTe films

DOEpatents

Gessert, Timothy A.

1999-01-01

A method of improving electrical contact to a thin film of a p-type tellurium-containing II-VI semiconductor comprising: depositing a first undoped layer of ZnTe on a thin film of p-type tellurium containing II-VI semiconductor with material properties selected to limit the formation of potential barriers at the interface between the p-CdTe and the undoped layer, to a thickness sufficient to control diffusion of the metallic-doped ZnTe into the p-type tellurim-containing II-VI semiconductor, but thin enough to minimize affects of series resistance; depositing a second heavy doped p-type ZnTe layer to the first layer using an appropriate dopant; and depositing an appropriate metal onto the outer-most surface of the doped ZnTe layer for connecting an external electrical conductor to an ohmic contact.

Thin-film solar cell fabricated on a flexible metallic substrate

DOEpatents

Tuttle, John R.; Noufi, Rommel; Hasoon, Falah S.

2006-05-30

A thin-film solar cell (10) is provided. The thin-film solar cell (10) comprises a flexible metallic substrate (12) having a first surface and a second surface. A back metal contact layer (16) is deposited on the first surface of the flexible metallic substrate (12). A semiconductor absorber layer (14) is deposited on the back metal contact. A photoactive film deposited on the semiconductor absorber layer (14) forms a heterojunction structure and a grid contact (24) deposited on the heterjunction structure. The flexible metal substrate (12) can be constructed of either aluminium or stainless steel. Furthermore, a method of constructing a solar cell is provided. The method comprises providing an aluminum substrate (12), depositing a semiconductor absorber layer (14) on the aluminum substrate (12), and insulating the aluminum substrate (12) from the semiconductor absorber layer (14) to inhibit reaction between the aluminum substrate (12) and the semiconductor absorber layer (14).

Thin-Film Solar Cell Fabricated on a Flexible Metallic Substrate

DOEpatents

Tuttle, J. R.; Noufi, R.; Hasoon, F. S.

2006-05-30

A thin-film solar cell (10) is provided. The thin-film solar cell (10) comprises a flexible metallic substrate (12) having a first surface and a second surface. A back metal contact layer (16) is deposited on the first surface of the flexible metallic substrate (12). A semiconductor absorber layer (14) is deposited on the back metal contact. A photoactive film deposited on the semiconductor absorber layer (14) forms a heterojunction structure and a grid contact (24) deposited on the heterjunction structure. The flexible metal substrate (12) can be constructed of either aluminium or stainless steel. Furthermore, a method of constructing a solar cell is provided. The method comprises providing an aluminum substrate (12), depositing a semiconductor absorber layer (14) on the aluminum substrate (12), and insulating the aluminum substrate (12) from the semiconductor absorber layer (14) to inhibit reaction between the aluminum substrate (12) and the semiconductor absorber layer (14).

The turnover and transport of vitamin D and of a polar metabolite with the properties of 25-hydroxycholecalciferol in human plasma

PubMed Central

Smith, John Edgar; Goodman, DeWitt S.

1971-01-01

Four normal men were injected intravenously with physiological doses (6 μg) of vitamin D3-1,2-3H. Serial samples of plasma were collected for 50 days. Total lipid extracts were chromatographed on silicic acid columns or thin-layer plates in order to characterize the radioactive components. Labeled vitamin D3 disappeared rapidly from plasma (initial half-life approximately 12 hr); after 7 days unchanged vitamin D3 represented less than 1% of circulating radioactivity. Coincident with vitamin D3 disappearance a more polar labeled metabolite appeared with chromatographic and other properties identical with those of 25-hydroxycholecalciferol. The disappearance of the more polar metabolite was relatively slow with a half-life of 19.6 ±0.6 days. A similar half-life was seen in a fifth subject, injected with 80 μg of vitamin D3-3H. Most (approximately 92%) of the plasma total radioactivity was represented by this component throughout the study. Plasma samples collected at various times were adjusted to density (d) 1.21 and were ultracentrifuged to separate plasma lipoproteins from proteins with d > 1.21. In all samples, almost all (mean 94%) of the radioactivity was found in association with proteins of d > 1.21. This observation was confirmed by bioassay, measuring uptake of 45Ca by intestinal slices. All plasma bioassayable vitamin D was found in association with proteins of d > 1.21; 55% of bioactivity was found in the chromatographic fraction corresponding to 25-hydroxycholecalciferol and 44% in the fractions representing vitamin D3. Since both vitamin D3 and its 25-hydroxy metabolite are lipid-soluble sterol derivatives, the finding that these compounds do not circulate in association with the known plasma lipoproteins provides presumptive evidence for the existence of a specific transport protein of d > 1.21. The transport protein for the polar metabolite has been partly characterized by gel filtration on Sephadex G-200 and by electrophoresis on polyacrylamide gel. The protein has an apparent size slightly smaller than plasma albumin (approximate mol wt 50,000-60,000) and an electrophoretic mobility very slightly greater than that of albumin. Studies are in progress to fractionate further and to characterize the transport protein. Images PMID:4330006

Direct charge carrier injection into Ga2O3 thin films using an In2O3 cathode buffer layer: their optical, electrical and surface state properties

NASA Astrophysics Data System (ADS)

Cui, W.; Zhao, X. L.; An, Y. H.; Guo, D. Y.; Qing, X. Y.; Wu, Z. P.; Li, P. G.; Li, L. H.; Cui, C.; Tang, W. H.

2017-04-01

Conductive Ga2O3 thin films with an In2O3 buffer layer have been prepared on c-plane sapphire substrates using a laser molecular beam epitaxy technique. The effects of the In2O3 buffer layer on the structure and optical, electrical and surface state properties of the Ga2O3 films have been studied. The change in conductivity of the thin films is attributed to different thicknesses of the In2O3 buffer layer, which determine the concentration of charge carriers injected into the upper Ga2O3 layer from the interface of the bilayer thin films. In addition, the increase in flat band voltage shift and capacitance values as the In2O3 buffer layer thickens are attributed to the increase in surface state density, which also contributes to the rapid shrinkage of the optical band gap of the Ga2O3. With transparency to visible light, high n-type conduction and the ability to tune the optical band gap and surface state density, we propose that Ga2O3/In2O3 bilayer thin film is an ideal n-type semiconductor for fabrication of transparent power devices, solar cell electrodes and gas sensors.

Synthesis of bimetallic nanostructures by nanosecond laser ablation of multicomponent thin films in water

NASA Astrophysics Data System (ADS)

Nikov, R. G.; Nedyalkov, N. N.; Atanasov, P. A.; Karashanova, D. B.

2018-03-01

The paper presents results on nanosecond laser ablation of thin films immersed in a liquid. The thin films were prepared by consecutive deposition of layers of different metals by thermal evaporation (first layer) and classical on-axis pulsed laser deposition (second layer); Ni/Au, Ag/Au and Ni/Ag thin films were thus deposited on glass substrates. The as-prepared films were then placed at the bottom of a glass vessel filled with double distilled water and irradiated by nanosecond laser pulses delivered by a Nd:YAG laser system at λ = 355 nm. This resulted in the formation of colloids of the thin films’ material. We also compared the processes of ablation of a bulk target and a thin film in the liquid by irradiating a Au target and a Au thin film by the same laser wavelength and fluence (λ = 355 nm, F = 5 J/cm2). The optical properties of the colloids were evaluated by optical transmittance measurements in the UV– VIS spectral range. Transmission electron microscopy was employed to estimate the particles’ size distribution.

Improvement in interfacial characteristics of low-voltage carbon nanotube thin-film transistors with solution-processed boron nitride thin films

NASA Astrophysics Data System (ADS)

Jeon, Jun-Young; Ha, Tae-Jun

2017-08-01

In this article, we demonstrate the potential of solution-processed boron nitride (BN) thin films for high performance single-walled carbon nanotube thin-film transistors (SWCNT-TFTs) with low-voltage operation. The use of BN thin films between solution-processed high-k dielectric layers improved the interfacial characteristics of metal-insulator-metal devices, thereby reducing the current density by three orders of magnitude. We also investigated the origin of improved device performance in SWCNT-TFTs by employing solution-processed BN thin films as an encapsulation layer. The BN encapsulation layer improves the electrical characteristics of SWCNT-TFTs, which includes the device key metrics of linear field-effect mobility, sub-threshold swing, and threshold voltage as well as the long-term stability against the aging effect in air. Such improvements can be achieved by reduced interaction of interfacial localized states with charge carriers. We believe that this work can open up a promising route to demonstrate the potential of solution-processed BN thin films on nanoelectronics.

Organic Field Effect Transistor Using Amorphous Fluoropolymer as Gate Insulating Film

NASA Astrophysics Data System (ADS)

Kitajima, Yosuke; Kojima, Kenzo; Mizutani, Teruyoshi; Ochiai, Shizuyasu

Organic field effect transistors are fabricated by the active layer of Regioregular poly (3-hexylthiophene-2,5-diy)(P3HT) thin film. CYTOP thin film made from Amorphous Fluoropolymer and fabricated by spin-coating is adopted to a gate dielectric layer on Polyethylenenaphthalate (PEN) thin film that is the substrate of an organic field effect transistor. The surface morphology and molecular orientation of P3HT thin films is observed by atomic force microscope (AFM) and X-Ray diffractometer (XRD). Grains are observed on the CYTOP thin film via an AFM image and the P3HT molecule is oriented perpendicularly on the CYTOP thin film. Based on the performance of the organic field effect transistor, the carrier mobility is 0.092 cm2/Vs, the ON/OFF ratio is 7, and the threshold voltage is -12 V. The ON/OFF ratio is relatively low and to improve On/Off ratio, the CYTOP/Polyimide double gate insulating layer is adopted to OFET.

Thin film absorber for a solar collector

DOEpatents

Wilhelm, William G.

1985-01-01

This invention pertains to energy absorbers for solar collectors, and more particularly to high performance thin film absorbers. The solar collectors comprising the absorber of this invention overcome several problems seen in current systems, such as excessive hardware, high cost and unreliability. In the preferred form, the apparatus features a substantially rigid planar frame with a thin film window bonded to one planar side of the frame. An absorber in accordance with the present invention is comprised of two thin film layers that are sealed perimetrically. In a preferred embodiment, thin film layers are formed from a metal/plastic laminate. The layers define a fluid-tight planar envelope of large surface area to volume through which a heat transfer fluid flows. The absorber is bonded to the other planar side of the frame. The thin film construction of the absorber assures substantially full envelope wetting and thus good efficiency. The window and absorber films stress the frame adding to the overall strength of the collector.

Organic photovoltaic cells utilizing ultrathin sensitizing layer

DOEpatents

Rand, Barry P [Princeton, NJ; Forrest, Stephen R [Princeton, NJ

2011-05-24

A photosensitive device includes a series of organic photoactive layers disposed between two electrodes. Each layer in the series is in direct contact with a next layer in the series. The series is arranged to form at least one donor-acceptor heterojunction, and includes a first organic photoactive layer comprising a first host material serving as a donor, a thin second organic photoactive layer comprising a second host material disposed between the first and a third organic photoactive layer, and the third organic photoactive layer comprising a third host material serving as an acceptor. The first, second, and third host materials are different. The thin second layer serves as an acceptor relative to the first layer or as a donor relative to the third layer.

In-depth evolution of chemical states and sub-10-nm-resolution crystal orientation mapping of nanograins in Ti(5 nm)/Au(20 nm)/Cr(3 nm) tri-layer thin films

NASA Astrophysics Data System (ADS)

Zhu, Xiaoli; Todeschini, Matteo; Bastos da Silva Fanta, Alice; Liu, Lintao; Jensen, Flemming; Hübner, Jörg; Jansen, Henri; Han, Anpan; Shi, Peixiong; Ming, Anjie; Xie, Changqing

2018-09-01

The applications of Au thin films and their adhesion layers often suffer from a lack of sufficient information about the chemical states of adhesion layers and about the high-lateral-resolution crystallographic morphology of Au nanograins. Here, we demonstrate the in-depth evolution of the chemical states of adhesive layers at the interfaces and the crystal orientation mapping of gold nanograins with a lateral resolution of less than 10 nm in a Ti/Au/Cr tri-layer thin film system. Using transmission electron microscopy, the variation in the interdiffusion at Cr/Au and Ti/Au interfaces was confirmed. From X-ray photoelectron spectroscopy (XPS) depth profiling, the chemical states of Cr, Au and Ti were characterized layer by layer, suggesting the insufficient oxidation of the adhesive layers. At the interfaces the Au 4f peaks shift to higher binding energies and this behavior can be described by a proposed model based on electron reorganization and substrate-induced final-state neutralization in small Au clusters supported by the partially oxidized Ti layer. Utilizing transmission Kikuchi diffraction (TKD) in a scanning electron microscope, the crystal orientation of Au nanograins between two adhesion layers was non-destructively characterized with sub-10 nm spatial resolution. The results provide nanoscale insights into the Ti/Au/Cr thin film system and contribute to our understanding of its behavior in nano-optic and nano-electronic devices.

Development of the α-IGZO/Ag/α-IGZO Triple-Layer Structure Films for the Application of Transparent Electrode.

PubMed

Chen, Kun-Neng; Yang, Cheng-Fu; Wu, Chia-Ching; Chen, Yu-Hsin

2017-02-24

We investigated the structural, optical, and electrical properties of amorphous IGZO/silver/amorphous IGZO (α-IGZO/Ag/α-IGZO) triple-layer structures that were deposited at room temperature on Eagle XG glass and flexible polyethylene terephthalate substrates through the sputtering method. Thin Ag layers with different thicknesses were inserted between two IGZO layers to form a triple-layer structure. Ag was used because of its lower absorption and resistivity. Field emission scanning electron microscopy measurements of the triple-layer structures revealed that the thicknesses of the Ag layers ranged from 13 to 41 nm. The thickness of the Ag layer had a large effect on the electrical and optical properties of the electrodes. The optimum thickness of the Ag metal thin film could be evaluated according to the optical transmittance, electrical conductivity, and figure of merit of the electrode. This study demonstrates that the α-IGZO/Ag/α-IGZO triple-layer transparent electrode can be fabricated with low sheet resistance (4.2 Ω/□) and high optical transmittance (88.1%) at room temperature without postannealing processing on the deposited thin films.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tesfaye, Meron; MacDonald, Andrew N.; Dudenas, Peter J.

Local gas transport limitation attributed to the ionomer thin-film in the catalyst layer is a major deterrent to widespread commercialization of polymer-electrolyte fuel cells. So far functionality and limitations of these thin-films have been assumed identical in the anode and cathode. In this study, Nafion ionomer thin-films on platinum(Pt) support were exposed to H 2 and air as model schemes, mimicking anode and cathode catalyst layers. Findings indicate decreased swelling, increased densification of ionomer matrix, and increased humidity-induced aging rates in reducing environment, compared to oxidizing and inert environments. Observed phenomenon could be related to underlying Pt-gas interaction dictating Pt-ionomermore » behavior. Presented results could have significant implications about the disparate behavior of ionomer thin-film in anode and cathode catalyst layers.« less

Spectroscopic Ellipsometry Studies of Ag and ZnO Thin Films and Their Interfaces for Thin Film Photovoltaics

NASA Astrophysics Data System (ADS)

Sainju, Deepak

Many modern optical and electronic devices, including photovoltaic devices, consist of multilayered thin film structures. Spectroscopic ellipsometry (SE) is a critically important characterization technique for such multilayers. SE can be applied to measure key parameters related to the structural, optical, and electrical properties of the components of multilayers with high accuracy and precision. One of the key advantages of this non-destructive technique is its capability of monitoring the growth dynamics of thin films in-situ and in real time with monolayer level precision. In this dissertation, the techniques of SE have been applied to study the component layer materials and structures used as back-reflectors and as the transparent contact layers in thin film photovoltaic technologies, including hydrogenated silicon (Si:H), copper indium-gallium diselenide (CIGS), and cadmium telluride (CdTe). The component layer materials, including silver and both intrinsic and doped zinc oxide, are fabricated on crystalline silicon and glass substrates using magnetron sputtering techniques. These thin films are measured in-situ and in real time as well as ex-situ by spectroscopic ellipsometry in order to extract parameters related to the structural properties, such as bulk layer thickness and surface roughness layer thickness and their time evolution, the latter information specific to real time measurements. The index of refraction and extinction coefficient or complex dielectric function of a single unknown layer can also be obtained from the measurement versus photon energy. Applying analytical expressions for these optical properties versus photon energy, parameters that describe electronic transport, such as electrical resistivity and electron scattering time, can be extracted. The SE technique is also performed as the sample is heated in order to derive the effects of annealing on the optical properties and derived electrical transport parameters, as well as the intrinsic temperature dependence of these properties and parameters. One of the major achievements of this dissertation research is the characterization of the thickness and optical properties of the interface layer formed between the silver and zinc oxide layers in a back-reflector structure used in thin film photovoltaics. An understanding of the impact of these thin film material properties on solar cell device performance has been complemented by applying reflectance and transmittance spectroscopy as well as simulations of cell performance.

Cu2ZnSnSe4 Thin Film Solar Cell with Depth Gradient Composition Prepared by Selenization of Sputtered Novel Precursors.

PubMed

Lai, Fang-I; Yang, Jui-Fu; Chen, Wei-Chun; Kuo, Shou-Yi

2017-11-22

In this study, we proposed a new method for the synthesis of the target material used in a two stage process for preparation of a high quality CZTSe thin film. The target material consisting of a mixture of Cu x Se and Zn x Sn 1-x alloy was synthesized, providing a quality CZTSe precursor layer for highly efficient CZTSe thin film solar cells. The CZTSe thin film can be obtained by annealing the precursor layers through a 30 min selenization process under a selenium atmosphere at 550 °C. The CZTSe thin films prepared by using the new precursor thin film were investigated and characterized using X-ray diffraction, Raman scattering, and photoluminescence spectroscopy. It was found that diffusion of Sn occurred and formed the CTSe phase and Cu x Se phase in the resultant CZTSe thin film. By selective area electron diffraction transmission electron microscopy images, the crystallinity of the CZTSe thin film was verified to be single crystal. By secondary ion mass spectroscopy measurements, it was confirmed that a double-gradient band gap profile across the CZTSe absorber layer was successfully achieved. The CZTSe solar cell with the CZTSe absorber layer consisting of the precursor stack exhibited a high efficiency of 5.46%, high short circuit current (J SC ) of 37.47 mA/cm 2 , open circuit voltage (V OC ) of 0.31 V, and fill factor (F.F.) of 47%, at a device area of 0.28 cm 2 . No crossover of the light and dark current-voltage (I-V) curves of the CZTSe solar cell was observed, and also, no red kink was observed under red light illumination, indicating a low defect concentration in the CZTSe absorber layer. Shunt leakage current with a characteristic metal/CZTSe/metal leakage current model was observed by temperature-dependent I-V curves, which led to the discovery of metal incursion through the CdS buffer layer on the CZTSe absorber layer. This leakage current, also known as space charge-limited current, grew larger as the measurement temperature increased and completely overwhelmed the diode current at a measurement temperature of 200 °C. This is due to interlayer diffusion of metal that increases the shunt leakage current and decreases the efficiency of the CZTSe thin film solar cells.

Characterization of crystallographic properties of thin films using X-ray diffraction

NASA Astrophysics Data System (ADS)

Zoo, Yeongseok

2007-12-01

Silver (Ag) has been recognized as one of promising candidates in Ultra-Large Scale Integrated (ULSI) applications in that it has the lowest bulk electrical resistivity of all pure metals and higher electromigration resistance than other interconnect materials. However, low thermal stability on Silicon Dioxide (Si02) at high temperatures (e.g., agglomeration) is considered a drawback for the Ag metallization scheme. Moreover, if a thin film is attached on a substrate, its properties may differ significantly from that of the bulk, since the properties of thin films can be significantly affected by the substrate. In this study, the Coefficient of Thermal Expansion (CTE) and texture evolution of Ag thin films on different substrates were characterized using various analytical techniques. The experimental results showed that the CTE of the Ag thin film was significantly affected by underlying substrate and the surface roughness of substrate. To investigate the alloying effect for Ag meatallization, small amounts of Copper (Cu) were added and characterized using theta-2theta X-ray Diffraction (XRD) scan and pole figure analysis. These XRD techniques are useful for investigating the primary texture of a metal film, (111) in this study, which (111) is the notation of a specific plane in the orthogonal coordinate system. They revealed that the (111) textures of Ag and Ag(Cu) thin films were enhanced with increasing temperature. Comparison of texture profiles between Ag and Ag(Cu) thin films showed that Cu additions enhanced (111) texture in Ag thin films. Accordingly, the texture enhancement in Ag thin films by Cu addition was discussed. Strained Silicon-On-Insulator (SSOI) is being considered as a potential substrate for Complementary Metal-Oxide-Semiconductor (CMOS) technology since the induced strain results in a significant improvement in device performance. High resolution X-ray diffraction (XRD) techniques were used to characterize the perpendicular and parallel strains in SSOI layers. XRD diffraction profiles generated from the crystalline SSOI layer provided a direct measurement of the layer's strain components. In addition, it has demonstrated that the rotational misalignment between the layer and the substrate can be incorporated within the biaxial strain equations for epitaxial layers. Based on these results, the strain behavior of the SSOI layer and the relation between strained Si and SiO2 layers are discussed for annealed samples.

Optimization of rotational speed for growing BaFe12O19 thin films using spin coating

NASA Astrophysics Data System (ADS)

Budiawanti, S.; Soegijono, B.; Mudzakir, I.; Suharno, Fadillah, L.

2017-07-01

Barium ferrite (BaFe12O19, BaM) thin films were fabricated by the spin coating of precursors obtained by using a sol-gel method. The effects of the rotational speed on the spin-coating process for growing a BaM thin film were investigated in this study. Coated films were heat-deposited at different rotational speeds ranging from 2000 to 4000 rpm, while the number of layers was set to nine. Further, the effect of the number of layers on the growth of BaM thin films was discussed. For this purpose, we take the layers number 1 to 12 and take the constant rotational speed of 3000 rpm. All the film were characterized using X-Ray diffraction, Scanning Electron microscope, and Energy-dispersive X-Ray spectroscopy and Vibrating Sample Magnetometer. It was found that by increasing the rotational speed the amount of material deposited on the Si substrate decreased. The measured grain size of the BaM thin film was nearly similar for three three different rotational speeds. However, the grain size was found to increase the number of layers.

GaN ultraviolet p-i-n photodetectors with enhanced deep ultraviolet quantum efficiency

NASA Astrophysics Data System (ADS)

Wang, Guosheng; Xie, Feng; Wang, Jun; Guo, Jin

2017-10-01

GaN ultraviolet (UV) p-i-n photodetectors (PDs) with a thin p-AlGaN/GaN contact layer are designed and fabricated. The PD exhibits a low dark current density of˜7 nA/cm2 under -5 V, and a zero-bias peak responsivity of ˜0.16 A/W at 360 nm, which corresponds to a maximum quantum efficiency of 55%. It is found that, in the wavelength range between 250 and 365 nm, the PD with thin p-AlGaN/GaN contact layer exhibits enhanced quantum efficiency especially in a deep-UV wavelength range, than that of the control PD with conventional thin p-GaN contact layer. The improved quantum efficiency of the PD with thin p-AlGaN/GaN contact layer in the deep-UV wavelength range is mainly attributed to minority carrier reflecting properties of thin p-AlGaN/GaN heterojunction which could reduce the surface recombination loss of photon-generated carriers and improve light current collection efficiency.

Elaboration and Characterization of TiO2 and Study of the Influence of The Number of Thin Films on the Methylene Blue Adsorption Rate

NASA Astrophysics Data System (ADS)

Madoui, Karima; Medjahed, Aicha; Hamici, Melia; Djamila, Abdi; Boudissa, Mokhtar

2018-05-01

Thin films of titanium oxide (TiO2) deposited on glass substrates were fabricated by using the sol-gel route. The realization of these thin layers was made using the dip-coating technique with a solution of titanium isopropoxyde as a precursor. The samples prepared with different numbers of deposited layers were annealed at 400 ° C for 2 hours. The main purposes of this work were investigations of both the effect of the number of thin TiO2 layers on the crystal structure of the anatase form first and, their ability to adsorb the solution of methylene blue in order to make colored filters from a photocatalytic process. The deposited titanium-oxide layers were characterized by using various techniques: namely, X-ray diffraction (XRD), Raman spectroscopy, atomic force microscopy (AFM) and UV-Visible spectrometry. The result obtained by using the XRD technique showed the appearance of an anatase phase, as was confirmed by using Raman spectroscopy. The AFM surface analysis allowed the surface topography to be characterized and the surface roughness to be measured, which increased with increasing number of layers. The UV-Visible spectra showed that the TiO2 films had a good transmittance varying from 65% to 95% according to the number of layers. The gap energy varied as a function of the number of deposited layers. The as deposited TiO2 layers were tested as a photocatalyst towards the adsorption of methylene blue dye. The results obtained during this study showed that the adsorption capacity varied according to the number of deposited thin layers and the exposing duration to ultraviolet (UV) light. The maximum absorption rate of the dye was obtained for the two-layer sample. Seventy-two hours of irradiation allowed the adsorption intensity of the dye to be maximized for two-layer films.

Ultraviolet emission enhancement in ZnO thin films modified by nanocrystalline TiO2

NASA Astrophysics Data System (ADS)

Zheng, Gaige; Lu, Xi; Qian, Liming; Xian, Fenglin

2017-05-01

In this study, nanocrystalline TiO2 modified ZnO thin films were prepared by electron beam evaporation. The structural, morphological and optical properties of the samples were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), UV-visible spectroscopy, fluorescence spectroscopy, respectively. The composition of the films was examined by energy dispersive X-ray spectroscopy (EDX). The photoluminescent spectrum shows that the pure ZnO thin film exhibits an ultraviolet (UV) emission peak and a strong green emission band. Surface analysis indicates that the ZnO thin film contains many oxygen vacancy defects on the surface. After the ZnO thin film is modified by the nanocrystalline TiO2 layer, the UV emission of ZnO is largely enhanced and the green emission is greatly suppressed, which suggests that the surface defects such as oxygen vacancies are passivated by the TiO2 capping layer. As for the UV emission enhancement of the ZnO thin film, the optimized thickness of the TiO2 capping layer is ∼16 nm. When the thickness is larger than 16 nm, the UV emission of the ZnO thin film will decrease because the TiO2 capping layer absorbs most of the excitation energy. The UV emission enhancement in the nanocrystalline TiO2 modified ZnO thin film can be attributed to surface passivation and flat band effect.

Effect of native oxide layers on copper thin-film tensile properties: A reactive molecular dynamics study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Skarlinski, Michael D., E-mail: michael.skarlinski@rochester.edu; Quesnel, David J.; Department of Mechanical Engineering, University of Rochester, Rochester, New York 14627

2015-12-21

Metal-oxide layers are likely to be present on metallic nano-structures due to either environmental exposure during use, or high temperature processing techniques such as annealing. It is well known that nano-structured metals have vastly different mechanical properties from bulk metals; however, difficulties in modeling the transition between metallic and ionic bonding have prevented the computational investigation of the effects of oxide surface layers. Newly developed charge-optimized many body [Liang et al., Mater. Sci. Eng., R 74, 255 (2013)] potentials are used to perform fully reactive molecular dynamics simulations which elucidate the effects that metal-oxide layers have on the mechanical propertiesmore » of a copper thin-film. Simulated tensile tests are performed on thin-films while using different strain-rates, temperatures, and oxide thicknesses to evaluate changes in yield stress, modulus, and failure mechanisms. Findings indicate that copper-thin film mechanical properties are strongly affected by native oxide layers. The formed oxide layers have an amorphous structure with lower Cu-O bond-densities than bulk CuO, and a mixture of Cu{sub 2}O and CuO charge character. It is found that oxidation will cause modifications to the strain response of the elastic modulii, producing a stiffened modulii at low temperatures (<75 K) and low strain values (<5%), and a softened modulii at higher temperatures. While under strain, structural reorganization within the oxide layers facilitates brittle yielding through nucleation of defects across the oxide/metal interface. The oxide-free copper thin-film yielding mechanism is found to be a tensile-axis reorientation and grain creation. The oxide layers change the observed yielding mechanism, allowing for the inner copper thin-film to sustain an FCC-to-BCC transition during yielding. The mechanical properties are fit to a thermodynamic model based on classical nucleation theory. The fit implies that the oxidation of the films reduces the activation volume for yielding.« less

Spatially and momentum resolved energy electron loss spectra from an ultra-thin PrNiO{sub 3} layer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kinyanjui, M. K., E-mail: michael.kinyanjui@uni-ulm.de; Kaiser, U.; Benner, G.

2015-05-18

We present an experimental approach which allows for the acquisition of spectra from ultra-thin films at high spatial, momentum, and energy resolutions. Spatially and momentum (q) resolved electron energy loss spectra have been obtained from a 12 nm ultra-thin PrNiO{sub 3} layer using a nano-beam electron diffraction based approach which enabled the acquisition of momentum resolved spectra from individual, differently oriented nano-domains and at different positions of the PrNiO{sub 3} thin layer. The spatial and wavelength dependence of the spectral excitations are obtained and characterized after the analysis of the experimental spectra using calculated dielectric and energy loss functions. The presentedmore » approach makes a contribution towards obtaining momentum-resolved spectra from nanostructures, thin film, heterostructures, surfaces, and interfaces.« less

Materials science and integration bases for fabrication of (BaxSr1-x)TiO3 thin film capacitors with layered Cu-based electrodes

NASA Astrophysics Data System (ADS)

Fan, W.; Kabius, B.; Hiller, J. M.; Saha, S.; Carlisle, J. A.; Auciello, O.; Chang, R. P. H.; Ramesh, R.

2003-11-01

The synthesis and fundamental material properties of layered TiAl/Cu/Ta electrodes were investigated to achieve the integration of Cu electrodes with high-dielectric constant (κ) oxide thin films for application to the fabrication of high-frequency devices. The Ta layer is an excellent diffusion barrier to inhibit deleterious Cu diffusion into the Si substrate, while the TiAl layer provides an excellent barrier against oxygen diffusion into the Cu layer to inhibit Cu oxidation during the growth of the high-κ layer in an oxygen atmosphere. Polycrystalline (BaxSr1-x)TiO3 (BST) thin films were grown on the Cu-based bottom electrode by rf magnetron sputtering at temperatures in the range 400-600 °C in oxygen, to investigate the performance of BST/Cu-based capacitors. Characterization of the Cu-based layered structure using surface analytical methods showed that two amorphous oxide layers were formed on both sides of the TiAl barrier, such that the oxide layer on the free surface of the TiAl layer correlates with TiAlOx, while the oxide layer at the TiAl/Cu interface is an Al2O3-rich layer. This double amorphous barrier layer structure effectively prevents oxygen penetration towards the underlying Cu and Ta layers. The TiAlOx interfacial layer, which has a relatively low dielectric constant compared with BST, reduced the total capacitance of the BST thin film capacitors. In addition, the layered electrode-oxide interface roughening observed during the growth of BST films at high temperature, due to copper grain growth, resulted in large dielectric loss on the fabricated BST capacitors. These problems were solved by growing the BST layer at 450 °C followed by a rapid thermal annealing at 700 °C. This process significantly reduced the thickness of the TiAlOx layer and interface roughness resulting in BST capacitors exhibiting properties suitable for the fabrication of high-performance high-frequency devices. In summary, relatively high dielectric constant (280), low dielectric loss (0.007), and low leakage current (<2×10-8 A/cm2 at 100 kV/cm) were achieved for BST thin film capacitors with Cu-based electrodes.

Using atomistic simulations to model cadmium telluride thin film growth

NASA Astrophysics Data System (ADS)

Yu, Miao; Kenny, Steven D.

2016-03-01

Cadmium telluride (CdTe) is an excellent material for low-cost, high efficiency thin film solar cells. It is important to conduct research on how defects are formed during the growth process, since defects lower the efficiency of solar cells. In this work we use computer simulation to predict the growth of a sputter deposited CdTe thin film. On-the-fly kinetic Monte Carlo technique is used to simulate the CdTe thin film growth on the (1 1 1) surfaces. The results show that on the (1 1 1) surfaces the growth mechanisms on surfaces which are terminated by Cd or Te are quite different, regardless of the deposition energy (0.1∼ 10 eV). On the Te-terminated (1 1 1) surface the deposited clusters first form a single mixed species layer, then the Te atoms in the mixed layer moved up to form a new layer. Whilst on the Cd-terminated (1 1 1) surface the new Cd and Te layers are formed at the same time. Such differences are probably caused by stronger bonding between ad-atoms and surface atoms on the Te layer than on the Cd layer.

Marangoni-Benard Convection in a Evaporating Liquid Thin Layer

NASA Technical Reports Server (NTRS)

Chai, An-Ti; Zhang, Nengli

1996-01-01

Marangoni-Benard convection in evaporating liquid thin layers has been investigated through flow visualization and temperature profile measurement. Twelve liquids, namely ethyl alcohol, methanol, chloroform, acetone, cyclohexane, benzine, methylene chloride, carbon tetrachloride, ethyl acetate, n-pentane, silicone oil (0.65 cSt.), and freon-113, were tested and convection patterns in thin layers of these samples were observed. Comparison among these tested samples shows that some liquids are sensitive to surface contamination from aluminum powder but some are not. The latter is excellent to be used for the investigation of surface-tension driven convection through visualization using the tracer. Two sample liquids, alcohol and freon-113 were particularly selected for systematic study. It was found that the wavelength of Benard cells would not change with thickness of the layer when it evaporates at room temperature. Special attention was focused on cases in which a liquid layer was cooled from below, and some interesting results were obtained. Convection patterns were recorded during the evaporation process and the patterns at certain time frame were compared. Benard cells were observed in thin layers with a nonlinear temperature profile and even with a zero or positive temperature gradient. Wavelength of the cells was found to increase as the evaporation progressed.

Solid oxide fuel cell having monolithic core

DOEpatents

Ackerman, John P.; Young, John E.

1984-01-01

A solid oxide fuel cell for electrochemically combining fuel and oxidant for generating galvanic output, wherein the cell core has an array of electrolyte and interconnect walls that are substantially devoid of any composite inert materials for support. Instead, the core is monolithic, where each electrolyte wall consists of thin layers of cathode and anode materials sandwiching a thin layer of electrolyte material therebetween, and each interconnect wall consists of thin layers of the cathode and anode materials sandwiching a thin layer of interconnect material therebetween. The electrolyte walls are arranged and backfolded between adjacent interconnect walls operable to define a plurality of core passageways alternately arranged where the inside faces thereof have only the anode material or only the cathode material exposed. Means direct the fuel to the anode-exposed core passageways and means direct the oxidant to the cathode-exposed core passageway; and means also direct the galvanic output to an exterior circuit. Each layer of the electrolyte and interconnect materials is of the order of 0.002-0.01 cm thick; and each layer of the cathode and anode materials is of the order of 0.002-0.05 cm thick.

Exciton-dominated dielectric function of atomically thin MoS 2 films

DOE PAGES

Yu, Yiling; Yu, Yifei; Cai, Yongqing; ...

2015-11-24

We systematically measure the dielectric function of atomically thin MoS 2 films with different layer numbers and demonstrate that excitonic effects play a dominant role in the dielectric function when the films are less than 5–7 layers thick. The dielectric function shows an anomalous dependence on the layer number. It decreases with the layer number increasing when the films are less than 5–7 layers thick but turns to increase with the layer number for thicker films. We show that this is because the excitonic effect is very strong in the thin MoS 2 films and its contribution to the dielectricmore » function may dominate over the contribution of the band structure. We also extract the value of layer-dependent exciton binding energy and Bohr radius in the films by fitting the experimental results with an intuitive model. The dominance of excitonic effects is in stark contrast with what reported at conventional materials whose dielectric functions are usually dictated by band structures. Lastly, the knowledge of the dielectric function may enable capabilities to engineer the light-matter interactions of atomically thin MoS 2 films for the development of novel photonic devices, such as metamaterials, waveguides, light absorbers, and light emitters.« less

High efficiency copper indium gallium diselenide (CIGS) thin film solar cells

NASA Astrophysics Data System (ADS)

Rajanikant, Ray Jayminkumar

The generation of electrical current from the solar radiation is known as the photovoltaic effect. Solar cell, also known as photovoltaic (PV) cell, is a device that works on the principle of photovoltaic effect, and is widely used for the generation of electricity. Thin film polycrystalline solar cells based on copper indium gallium diselenide (CIGS) are admirable candidates for clean energy production with competitive prices in the near future. CIGS based polycrystalline thin film solar cells with efficiencies of 20.3 % and excellent temperature stability have already been reported at the laboratory level. The present study discusses about the fabrication of CIGS solar cell. Before the fabrication part of CIGS solar cell, a numerical simulation is carried out using One-Dimensional Analysis of Microelectronic and Photonic Structures (AMPS-ID) for understanding the physics of a solar cell device, so that an optimal structure is analyzed. In the fabrication part of CIGS solar cell, Molybdenum (Mo) thin film, which acts as a 'low' resistance metallic back contact, is deposited by RF magnetron sputtering on organically cleaned soda lime glass substrate. The major advantages for using Mo are high temperature, (greater than 600 °C), stability and inertness to CIGS layer (i.e., no diffusion of CIGS into Mo). Mo thin film is deposited at room temperature (RT) by varying the RF power and the working pressure. The Mo thin films deposited with 100 W RF power and 1 mTorr working pressure show a reflectivity of above average 50 % and the low sheet resistance of about 1 O/□. The p-type CIGS layer is deposited on Mo. Before making thin films of CIGS, a powder of CIGS material is synthesized using melt-quenching method. Thin films of CIGS are prepared by a single-stage flash evaporation process on glass substrates, initially, for optimization of deposition parameters and than on Mo coated glass substrates for device fabrication. CIGS thin film is deposited at 250 °C at a pressure of 10-5 mbar. The thickness of the film was kept 1 mum for the solar cell device preparation. Rapid Thermal Annealing (RTA) is carried out of CIGS thin film at 500 °C for 2 minutes in the argon atmosphere. Annealing process mainly improves the grain growth of the CIGS and, hence the surface roughness, which is essential for a multilayered semiconductor structure. Thin layer of n-type highly resistive cadmium sulphide (CdS), generally known as a "buffer" layer, is deposited on CIGS layer by thermal and flash evaporation method at the substrate temperature of 100 °C. The CdS thin film plays a crucial role in the formation of the p-n junction and thus the solar cell device performance. The effect of CdS film substrate temperature ranging from 50 °C to 200 °C is observed. At the 100 °C substrate temperature, CdS thin film shows the near to 85 % of transmission in the visible region and resistivity of the order of greater then 20 x 109 Ocm, which are the essential characteristics of buffer layer. The bi-layer structure of ZnO, containing 70 nm i-ZnO and 500 nm aluminum (Al) doped ZnO, act as a transparent front-contact for CIGS thin film solar cell. These layers were deposited using RF magnetron sputtering. i-ZnO thin film acts as an insulating layer, which prevents the recombination of the photo-generated carries and also minimizes the lattice miss match defects between CdS and Al-ZnO. The resistivity of iZnO and Al-ZnO is of the order of 1012 Ocm and 10-4 Ocm, respectively. Al-ZnO thin films act as transparent conducting top electrode having transparency of about 85 % in the visible region. On Al-ZnO layer the finger-type grid pattern of silver (Ag), 200 nm thick, is deposited for the collection of photo-generated carriers. The thin film based multilayered structure Mo / CIGS / CdS / i-ZnO / Al-ZnO / Ag grid of CIGS solar cell is grown one by one on a single glass substrate. As-prepared CIGS solar cell device shows a minute photovoltaic effect. For the further improvement of the cell we have varied the thickness of the buffer layer i.e. CdS. In addition, the deposition of CdS is carried out using flash evaporation method to improve the CIGS/CdS junction. Heat soak pulses of about 200 °C are also applied for 20 sec for the further upgrading the junction. To protect the CIGS/CdS junction from the high-energy sputtered particles of ZnO, a fine mesh of stainless steel is placed just before the sample holder to enhance the performance of the solar cell. The influence of the thickness of iZnO and CdS has been checked. The maximum V oe and Jsc of about 138 mV and 1.3 mA/cm2 , respectively, are achieved using flash evaporated CIGS layer and flash evaporated CdS thin film. Further improvement of current performance can be done either by adopting some other fabrication method to obtain a denser CIGS absorber layer or replacing the CdS layer with some other efficient buffer layer.

Method of forming contacts for a back-contact solar cell

DOEpatents

Manning, Jane

2013-07-23

Methods of forming contacts for back-contact solar cells are described. In one embodiment, a method includes forming a thin dielectric layer on a substrate, forming a polysilicon layer on the thin dielectric layer, forming and patterning a solid-state p-type dopant source on the polysilicon layer, forming an n-type dopant source layer over exposed regions of the polysilicon layer and over a plurality of regions of the solid-state p-type dopant source, and heating the substrate to provide a plurality of n-type doped polysilicon regions among a plurality of p-type doped polysilicon regions.

Observations of metal concentrations in E-region sporadic thin layers using incoherent-scatter radar

NASA Astrophysics Data System (ADS)

Suzuki, Nobuhiro

This thesis has used incoherent-scatter radar data from the facility at Sondrestrom, Greenland to determine the ion mass values inside thin sporadic-E layers in the lower ionosphere. Metallic positively-charged ions of meteoric origin are deposited in the earth's upper atmosphere over a height range of about 85-120 km. Electric fields and neutral-gas (eg N2, O, O2) winds at high latitudes may produce convergent ion dynamics that results in the re-distribution of the background altitude distribution of the ions to form thin (1-3 km) high-density layers that are detectable with radar. A large database of experimental radar observations has been processed to determine ion mass values inside these thin ion layers. The range resolution of the radar was 600 meters that permitted mass determinations at several altitude steps within the layers. Near the lower edge of the layers the ion mass values were in the range 20-25 amu while at the top portion of the layers the mass values were generally in the range 30-40 amu. The numerical values are consistent with in-situ mass spectrometer data obtained by other researchers that suggest these layers are mainly composed of a mixture or Mg +, Si+, and Fe + ions. The small tendency for heavier ions to reside at the top portion of the layers is consistent with theory. The results have also found new evidence for the existence of complex-shaped multiple layers; the examples studied suggest similar ion mass values in different layers that in some cases are separated in altitude by several km.

The effects of GaN nanocolumn arrays and thin SixNy buffer layers on the morphology of GaN layers grown by plasma-assisted molecular beam epitaxy on Si(111) substrates

NASA Astrophysics Data System (ADS)

Shubina, K. Yu; Pirogov, E. V.; Mizerov, A. M.; Nikitina, E. V.; Bouravleuv, A. D.

2018-03-01

The effects of GaN nanocolumn arrays and a thin SixNy layer, used as buffer layers, on the morphology of GaN epitaxial layers are investigated. Two types of samples with different buffer layers were synthesized by PA-MBE. The morphology of the samples was characterized by SEM. The crystalline quality of the samples was assessed by XRD. The possibility of synthesis of continuous crystalline GaN layers on Si(111) substrates without the addition of other materials such as aluminum nitride was demonstrated.

Thin layer asphaltic concrete density measuring using nuclear gages.

DOT National Transportation Integrated Search

1989-03-01

A Troxler 4640 thin layer nuclear gage was evaluated under field conditions to determine if it would provide improved accuracy of density measurements on asphalt overlays of 1-3/4 and 2 inches in thickness. Statistical analysis shows slightly improve...

High-performance thin layer chromatography to assess pharmaceutical product quality.

PubMed

Kaale, Eliangiringa; Manyanga, Vicky; Makori, Narsis; Jenkins, David; Michael Hope, Samuel; Layloff, Thomas

2014-06-01

To assess the sustainability, robustness and economic advantages of high-performance thin layer chromatography (HPTLC) for quality control of pharmaceutical products. We compared three laboratories where three lots of cotrimoxazole tablets were assessed using different techniques for quantifying the active ingredient. The average assay relative standard deviation for the three lots was 1.2 with a range of 0.65-2.0. High-performance thin layer chromatography assessments are yielding valid results suitable for assessing product quality. The local pharmaceutical manufacturer had evolved the capacity to produce very high quality products. © 2014 John Wiley & Sons Ltd.

[Thin layer agar represents a cost-effective alternative for the rapid diagnosis of multi-drug resistant tuberculosis].

PubMed

Hernández-Sarmiento, José M; Martínez-Negrete, Milton A; Castrillón-Velilla, Diana M; Mejía-Espinosa, Sergio A; Mejía-Mesa, Gloria I; Zapata-Fernández, Elsa M; Rojas-Jiménez, Sara; Marín-Castro, Andrés E; Robledo-Restrepo, Jaime A

2014-01-01

Using cost-benefit analysis for comparing the thin-layer agar culture method to the standard multiple proportion method used in diagnosing multidrug-resistant tuberculosis (MDR TB). A cost-benefit evaluation of two diagnostic tests was made at the Corporación para Investigaciones Biológicas (CIB) in Medellín, Colombia. 100 patients were evaluated; 10.8% rifampicin resistance and 14.3% isoniazid resistance were found. A computer-based decision tree model was used for cost-effectiveness analysis (Treeage Pro); the thin-layer agar culture method was most cost-effective, having 100% sensitivity, specificity and predictive values for detecting rifampicin and isoniazid resistance. The multiple proportion method value was calculated as being US$ 71 having an average 49 day report time compared to US$ 18 and 14 days for the thin-layer agar culture method. New technologies have been developed for diagnosing tuberculosis which are apparently faster and more effective; their operating characteristics must be evaluated as must their effectiveness in terms of cost-benefit. The present study established that using thin-layer agar culture was cheaper, equally effective and could provide results more quickly than the traditional method. This implies that a patient could receive MDR TB treatment more quickly.

Enhanced stability of thin film transistors with double-stacked amorphous IWO/IWO:N channel layer

NASA Astrophysics Data System (ADS)

Lin, Dong; Pi, Shubin; Yang, Jianwen; Tiwari, Nidhi; Ren, Jinhua; Zhang, Qun; Liu, Po-Tsun; Shieh, Han-Ping

2018-06-01

In this work, bottom-gate top-contact thin film transistors with double-stacked amorphous IWO/IWO:N channel layer were fabricated. Herein, amorphous IWO and N-doped IWO were deposited as front and back channel layers, respectively, by radio-frequency magnetron sputtering. The electrical characteristics of the bi-layer-channel thin film transistors (TFTs) were examined and compared with those of single-layer-channel (i.e., amorphous IWO or IWO:N) TFTs. It was demonstrated to exhibit a high mobility of 27.2 cm2 V‑1 s‑1 and an on/off current ratio of 107. Compared to the single peers, bi-layer a-IWO/IWO:N TFTs showed smaller hysteresis and higher stability under negative bias stress and negative bias temperature stress. The enhanced performance could be attributed to its unique double-stacked channel configuration, which successfully combined the merits of the TFTs with IWO and IWO:N channels. The underlying IWO thin film provided percolation paths for electron transport, meanwhile, the top IWO:N layer reduced the bulk trap densities. In addition, the IWO channel/gate insulator interface had reduced defects, and IWO:N back channel surface was insensitive to the ambient atmosphere. Overall, the proposed bi-layer a-IWO/IWO:N TFTs show potential for practical applications due to its possibly long-term serviceability.

Development of buffer layer structure for epitaxial growth of (100)/(001)Pb(Zr,Ti)O3-based thin film on (111)Si wafer

NASA Astrophysics Data System (ADS)

Hayasaka, Takeshi; Yoshida, Shinya; Tanaka, Shuji

2017-07-01

This paper reports on the development of a novel buffer layer structure, (100)SrRuO3/(100)LaNiO3/(111)Pt/(111)CeO2, for the epitaxial growth of a (100)/(001)-oriented Pb(Zr,Ti)O3 (PZT)-based thin film on a (111)Si wafer. (111)Pt and (111)CeO2 were epitaxially grown on (111)Si straightforwardly. Then, the crystal orientation was forcibly changed from (111) to (100) at the LaNiO3 layer owing to its strong (100)-self-orientation property, which enabled the cube-on-cube epitaxial growth of the subsequent (100)SrRuO3 layer and preferentially (100)/(001)-oriented PZT-based thin film. The PZT-based epitaxial thin films were comprehensively characterized in terms of the crystallinity, in-plane epitaxial relationships, piezoelectricity, and so forth. This buffer layer structure for the epitaxial growth of PZT can be applied to piezoelectric micro-electro-mechanical systems (MEMS) vibrating ring gyroscopes.

Direct numerical simulation of turbulent Rayleigh-Bénard convection in a vertical thin disk

NASA Astrophysics Data System (ADS)

Xu, Wei; Wang, Yin; He, Xiao-Zhou; Yik, Hiu-Fai; Wang, Xiao-Ping; Schumacher, Jorg; Tong, Penger

2017-11-01

We report a direct numerical simulation (DNS) of turbulent Rayleigh-Bénard convection in a thin vertical disk with a high-order spectral element method code NEK5000. An unstructured mesh is used to adapt the turbulent flow in the thin disk and to ensure that the mesh sizes satisfy the refined Groetzbach criterion and a new criterion for thin boundary layers proposed by Shishkina et al. The DNS results for the mean and variance temperature profiles in the thermal boundary layer region are found to be in good agreement with the predictions of the new boundary layer models proposed by Shishkina et al. and Wang et al.. Furthermore, we numerically calculate the five budget terms in the boundary layer equation, which are difficult to measure in experiment. The DNS results agree well with the theoretical predictions by Wang et al. Our numerical work thus provides a strong support for the development of a common framework for understanding the effect of boundary layer fluctuations. This work was supported in part by Hong Kong Research Grants Council.

High density nonmagnetic cobalt in thin films

NASA Astrophysics Data System (ADS)

Banu, Nasrin; Singh, Surendra; Basu, Saibal; Roy, Anupam; Movva, Hema C. P.; Lauter, V.; Satpati, B.; Dev, B. N.

2018-05-01

Recently high density (HD) nonmagnetic cobalt has been discovered in a nanoscale cobalt thin film, grown on Si(111) single crystal. This form of cobalt is not only nonmagnetic but also superconducting. These promising results have encouraged further investigations of the growth of the nonmagnetic (NM) phase of cobalt. In the original investigation, the cobalt film had a natural cobalt oxide at the top. We have investigated whether the growth of HD NM cobalt layers in the thin film depends on (i) a capping layer on the cobalt film, (ii) the thickness of the cobalt film and (iii) the nature of the substrate on which the cobalt film is grown. The results of such investigations indicate that for cobalt films capped with a thin gold layer, and for various film thicknesses, HD NM cobalt layers are formed. However, instead of a Si substrate, when the cobalt films are grown on oxide substrates, such as silicon oxide or cobalt oxide, HD NM cobalt layers are not formed. The difference is attributed to the nature—crystalline or amorphous—of the substrate.

Impact of ultra-thin Al2O3-y layers on TiO2-x ReRAM switching characteristics

NASA Astrophysics Data System (ADS)

Trapatseli, Maria; Cortese, Simone; Serb, Alexander; Khiat, Ali; Prodromakis, Themistoklis

2017-05-01

Transition metal-oxide resistive random access memory devices have demonstrated excellent performance in switching speed, versatility of switching and low-power operation. However, this technology still faces challenges like poor cycling endurance, degradation due to high electroforming (EF) switching voltages and low yields. Approaches such as engineering of the active layer by doping or addition of thin oxide buffer layers have been often adopted to tackle these problems. Here, we have followed a strategy that combines the two; we have used ultra-thin Al2O3-y buffer layers incorporated between TiO2-x thin films taking into account both 3+/4+ oxidation states of Al/Ti cations. Our devices were tested by DC and pulsed voltage sweeping and in both cases demonstrated improved switching voltages. We believe that the Al2O3-y layers act as reservoirs of oxygen vacancies which are injected during EF, facilitate a filamentary switching mechanism and provide enhanced filament stability, as shown by the cycling endurance measurements.

Electrically tunable infrared metamaterial devices

DOEpatents

Brener, Igal; Jun, Young Chul

2015-07-21

A wavelength-tunable, depletion-type infrared metamaterial optical device is provided. The device includes a thin, highly doped epilayer whose electrical permittivity can become negative at some infrared wavelengths. This highly-doped buried layer optically couples with a metamaterial layer. Changes in the transmission spectrum of the device can be induced via the electrical control of this optical coupling. An embodiment includes a contact layer of semiconductor material that is sufficiently doped for operation as a contact layer and that is effectively transparent to an operating range of infrared wavelengths, a thin, highly doped buried layer of epitaxially grown semiconductor material that overlies the contact layer, and a metallized layer overlying the buried layer and patterned as a resonant metamaterial.

Thin film solar cell including a spatially modulated intrinsic layer

DOEpatents

Guha, Subhendu; Yang, Chi-Chung; Ovshinsky, Stanford R.

1989-03-28

One or more thin film solar cells in which the intrinsic layer of substantially amorphous semiconductor alloy material thereof includes at least a first band gap portion and a narrower band gap portion. The band gap of the intrinsic layer is spatially graded through a portion of the bulk thickness, said graded portion including a region removed from the intrinsic layer-dopant layer interfaces. The band gap of the intrinsic layer is always less than the band gap of the doped layers. The gradation of the intrinsic layer is effected such that the open circuit voltage and/or the fill factor of the one or plural solar cell structure is enhanced.

Pulsed laser deposition of functionalized Mg-Al layered double hydroxide thin films

NASA Astrophysics Data System (ADS)

Vlad, A.; Birjega, R.; Tirca, I.; Matei, A.; Mardare, C. C.; Hassel, A. W.; Nedelcea, A.; Dinescu, M.; Zavoianu, R.

2018-02-01

In this paper, magnesium-aluminium layered double hydroxide (LDH) has been functionalized with sodium dodecyl sulfate (DS) and deposited as thin film by pulsed laser deposition (PLD). Mg, Al-LDH powders were prepared by co-precipitation and used as reference material. Intercalation of DS as an anionic surfactant into the LDHs host layers has been prepared in two ways: co-precipitation (P) and reconstruction (R). DS intercalation occurred in LDH powder via both preparation methods. The films deposited via PLD, in particular at 532 and 1064 nm, preserve the organic intercalated layered structure of the targets prepared from these powders. The results reveal the ability of proposed deposition technique to produce functional composite organo-modified LDHs thin films.

Fabrication and Structural Characterization of an Ultrathin Film of a Two-Dimensional-Layered Metal-Organic Framework, {Fe(py)2[Ni(CN)4]} (py = pyridine).

PubMed

Sakaida, Shun; Haraguchi, Tomoyuki; Otsubo, Kazuya; Sakata, Osami; Fujiwara, Akihiko; Kitagawa, Hiroshi

2017-07-17

We report the fabrication and characterization of the first example of a tetracyanonickelate-based two-dimensional-layered metal-organic framework, {Fe(py) 2 Ni(CN) 4 } (py = pyridine), thin film. To fabricate a nanometer-sized thin film, we utilized the layer-by-layer method, whereby a substrate was alternately soaked in solutions of the structural components. Surface X-ray studies revealed that the fabricated film was crystalline with well-controlled growth directions both parallel and perpendicular to the substrate. In addition, lattice parameter analysis indicated that the crystal system is found to be close to higher symmetry by being downsized to a thin film.

Treatment of ice cover and other thin elastic layers with the parabolic equation method.

PubMed

Collins, Michael D

2015-03-01

The parabolic equation method is extended to handle problems involving ice cover and other thin elastic layers. Parabolic equation solutions are based on rational approximations that are designed using accuracy constraints to ensure that the propagating modes are handled properly and stability constrains to ensure that the non-propagating modes are annihilated. The non-propagating modes are especially problematic for problems involving thin elastic layers. It is demonstrated that stable results may be obtained for such problems by using rotated rational approximations [Milinazzo, Zala, and Brooke, J. Acoust. Soc. Am. 101, 760-766 (1997)] and generalizations of these approximations. The approach is applied to problems involving ice cover with variable thickness and sediment layers that taper to zero thickness.

Biotechnology Conference: Diagnostics 󈨛 Held in Cambridge, England on 10 and 11 December 1987.

DTIC Science & Technology

1988-05-25

settings. 1 -hour culture confirmation test for herpes (ColorGene DNA hybridization test for HSV confirmation). This test NEW AMPEROMETRIC BIOSENSORS...I Thin Layer Technology: Monolayers to Multi Thin Films ................. 1 Single-Step Immunoassay Systems...if this thin-layer pr•ccss~is probe technolh,,y. and biosensors. The aim of the con- demonstrated in Figure 1 . which shows the disposition of ference

Epitaxial growth of metallic buffer layer structure and c-axis oriented Pb(Mn1/3,Nb2/3)O3-Pb(Zr,Ti)O3 thin film on Si for high performance piezoelectric micromachined ultrasonic transducer

NASA Astrophysics Data System (ADS)

Thao, Pham Ngoc; Yoshida, Shinya; Tanaka, Shuji

2017-12-01

This paper reports on the development of a metallic buffer layer structure, (100) SrRuO3 (SRO)/(100) Pt/(100) Ir/(100) yttria-stabilized zirconia (YSZ) layers for the epitaxial growth of a c-axis oriented Pb(Mn1/3,Nb2/3)O3-Pb(Zr,Ti)O3 (PMnN-PZT) thin film on a (100) Si wafer for piezoelectric micro-electro mechanical systems (MEMS) application. The stacking layers were epitaxially grown on a Si substrate under the optimal deposition condition. A crack-free PMnN-PZT epitaxial thin films was obtained at a thickness up to at least 1.7 µm, which is enough for MEMS applications. The unimorph MEMS cantilevers based on the PMnN-PZT thin film were fabricated and characterized. As a result, the PMnN-PZT thin film exhibited -10 to -12 C/m2 as a piezoelectric coefficient e 31,f and ˜250 as a dielectric constants ɛr. The resultant FOM for piezoelectric micromachined ultrasonic transducer (pMUT) is higher than those of general PZT and AlN thin films. This structure has a potential to provide high-performance pMUTs.

Apparatus for forming thin-film heterojunction solar cells employing materials selected from the class of I-III-VI.sub.2 chalcopyrite compounds

DOEpatents

Mickelsen, Reid A.; Chen, Wen S.

1983-01-01

Apparatus for forming thin-film, large area solar cells having a relatively high light-to-electrical energy conversion efficiency and characterized in that the cell comprises a p-n-type heterojunction formed of: (i) a first semiconductor layer comprising a photovoltaic active material selected from the class of I-III-VI.sub.2 chalcopyrite ternary materials which is vacuum deposited in a thin "composition-graded" layer ranging from on the order of about 2.5 microns to about 5.0 microns (.congruent.2.5 .mu.m to .congruent.5.0 .mu.m) and wherein the lower region of the photovoltaic active material preferably comprises a low resistivity region of p-type semiconductor material having a superimposed region of relatively high resistivity, transient n-type semiconductor material defining a transient p-n homojunction; and (ii), a second semiconductor layer comprising a low resistivity n-type semiconductor material wherein interdiffusion (a) between the elemental constituents of the two discrete juxtaposed regions of the first semiconductor layer defining a transient p-n homojunction layer, and (b) between the transient n-type material in the first semiconductor layer and the second n-type semiconductor layer, causes the transient n-type material in the first semiconductor layer to evolve into p-type material, thereby defining a thin layer heterojunction device characterized by the absence of voids, vacancies and nodules which tend to reduce the energy conversion efficiency of the system.

High Performance Thin Layer Chromatography.

ERIC Educational Resources Information Center

Costanzo, Samuel J.

1984-01-01

Clarifies where in the scheme of modern chromatography high performance thin layer chromatography (TLC) fits and why in some situations it is a viable alternative to gas and high performance liquid chromatography. New TLC plates, sample applications, plate development, and instrumental techniques are considered. (JN)

Extraction chromatographic separation of Am(III) and Eu(III) by TPEN-immobilized gel

DOE Office of Scientific and Technical Information (OSTI.GOV)

Takeshita, K.; Ogata, T.; Oaki, H.

2013-07-01

A TPEN derivative with 4 vinyl groups, N,N,N',N' -tetrakis-(4-propenyloxy-2-pyridylmethyl)ethylenediamine (TPPEN) was synthesized for the separation of trivalent minor actinides (Am(III)) and lanthanides (Eu(III)). A co-polymer gel with TPPEN and N-isopropylacrylamide (NIPA) showed a high separation factor of Am(III) over Eu(III) (SF[Am/Eu]), which was evaluated to be 26 at pH=5. Thin film of NIPA-TPPEN gel (average thickness: 2-40 nm) was immobilized on the pore surface in porous silica particles (particle diameter : 50 μm, average pore diameter : 50 and 300 nm) and a chromatographic column (diameter: 6 mm, height: 11 mm) packed with the gel-coated particles was prepared. A smallmore » amount of weakly acidic solution (pH=4) containing Am(III) and Eu(III) was supplied in the column and the elution tests of Am(III) and Eu(III) were carried out. Eu(III) was recovered separately by a weakly acidic eluent (pH=4) at 313 K and Am(III) by a highly acidic eluent (pH=2) at 298 K. These results suggest that the contentious separation of minor actinides and lanthanides is attainable by a new extraction chromatographic process with two columns adjusted to 298 K and 313 K. (authors)« less

Chemical analysis of aerosol in the Venusian cloud layer by reaction gas chromatography on board the Vega landers

NASA Technical Reports Server (NTRS)

Gelman, B. G.; Drozdov, Y. V.; Melnikov, V. V.; Rotin, V. A.; Khokhlov, V. N.; Bondarev, V. B.; Dolnikov, G. G.; Dyachkov, A. V.; Nenarokov, D. F.; Mukhin, L. M.

1986-01-01

The experiment on sulfuric acid aerosol determination in the Venusian cloud layer on board the Vega landers is described. An average content of sulfuric acid of approximately 1 mg/cu m was found for the samples taken from the atmosphere at heights from 63 to 48 km and analyzed with the SIGMA-3 chromatograph. Sulfur dioxide (SO2) was revealed in the gaseous sample at the height of 48 km. From the experimental results and blank run measurements, a suggestion is made that the Venusian cloud layer aerosol consists of more complicated particles than the sulfuric acid water solution does.

In situ modification of chromatography adsorbents using cold atmospheric pressure plasmas

NASA Astrophysics Data System (ADS)

Olszewski, P.; Willett, T. C.; Theodosiou, E.; Thomas, O. R. T.; Walsh, J. L.

2013-05-01

Efficient manufacturing of increasingly sophisticated biopharmaceuticals requires the development of new breeds of chromatographic materials featuring two or more layers, with each layer affording different functions. This letter reports the in situ modification of a commercial beaded anion exchange adsorbent using atmospheric pressure plasma generated within gas bubbles. The results show that exposure to He-O2 plasma in this way yields significant reductions in the surface binding of plasmid DNA to the adsorbent exterior, with minimal loss of core protein binding capacity; thus, a bi-layered chromatography material exhibiting both size excluding and anion exchange functionalities within the same bead is produced.

Exploring substrate/ionomer interaction under oxidizing and reducing environments

DOE PAGES

Tesfaye, Meron; MacDonald, Andrew N.; Dudenas, Peter J.; ...

2018-02-09

Local gas transport limitation attributed to the ionomer thin-film in the catalyst layer is a major deterrent to widespread commercialization of polymer-electrolyte fuel cells. So far functionality and limitations of these thin-films have been assumed identical in the anode and cathode. In this study, Nafion ionomer thin-films on platinum(Pt) support were exposed to H 2 and air as model schemes, mimicking anode and cathode catalyst layers. Findings indicate decreased swelling, increased densification of ionomer matrix, and increased humidity-induced aging rates in reducing environment, compared to oxidizing and inert environments. Observed phenomenon could be related to underlying Pt-gas interaction dictating Pt-ionomermore » behavior. Presented results could have significant implications about the disparate behavior of ionomer thin-film in anode and cathode catalyst layers.« less

Method for synthesizing thin film electrodes

DOEpatents

Boyle, Timothy J [Albuquerque, NM

2007-03-13

A method for making a thin-film electrode, either an anode or a cathode, by preparing a precursor solution using an alkoxide reactant, depositing multiple thin film layers with each layer approximately 500 1000 .ANG. in thickness, and heating the layers to above 600.degree. C. to achieve a material with electrochemical properties suitable for use in a thin film battery. The preparation of the anode precursor solution uses Sn(OCH.sub.2C(CH.sub.3).sub.3).sub.2 dissolved in a solvent in the presence of HO.sub.2CCH.sub.3 and the cathode precursor solution is formed by dissolving a mixture of (Li(OCH.sub.2C(CH.sub.3).sub.3)).sub.8 and Co(O.sub.2CCH.sub.3).H.sub.2O in at least one polar solvent.

Electrochemical Atomic Layer Epitaxy of Thin Film CdSe

NASA Astrophysics Data System (ADS)

Pham, L.; Kaleida, K.; Happek, U.; Mathe, M. K.; Vaidyanathan, R.; Stickney, J. L.; Radevic, M.

2002-10-01

Electrochemical atomic layer epitaxy (EC-ALE) is a current developmental technique for the fabrication of compound semiconductor thin films. The deposition of elements making up the compound utilizes surface limited reactions where the potential is less than that required for bulk growth. This growth method offers mono-atomic layer control, allowing the deposition of superlattices with sharp interfaces. Here we report on the EC-ALE formation of CdSe thin films on Au and Cu substrates using an automated flow cell system. The band gap was measured using IR absorption and photoconductivity and found to be consistent with the literature value of 1.74 eV at 300K and 1.85 eV at 20K. The stoichiometry of the thin film was confirmed with electron microprobe analysis and x-ray diffraction.

Characterization of Softmagnetic Thin Layers Using Barkhausen Noise Microscopy

DTIC Science & Technology

2001-04-01

magnetoresistive (MR) sensors softmagnetic thin layer systems are used. Optimal performance of these layers requires homogeneous magnetic properties , especially a...Sendust, used in inductive sensors and nanocrystalline NiFe , used in MR-sensors. In quality correlations to Barkhausen noise parameters were found...Brillouin scattering are frequently used. An important issue is the influence of mechanical properties , e.g. residual stress on the magnetic performance

Flexible Thin Metal Film Thermal Sensing System

NASA Technical Reports Server (NTRS)

Thomsen, Donald Laurence (Inventor)

2012-01-01

A flexible thin metal film thermal sensing system is provided. A thermally-conductive film made from a thermally-insulating material is doped with thermally-conductive material. At least one layer of electrically-conductive metal is deposited directly onto a surface of the thermally-conductive film. One or more devices are coupled to the layer(s) to measure an electrical characteristic associated therewith as an indication of temperature.

Optical sensors and multisensor arrays containing thin film electroluminescent devices

DOEpatents

Aylott, Jonathan W.; Chen-Esterlit, Zoe; Friedl, Jon H.; Kopelman, Raoul; Savvateev, Vadim N.; Shinar, Joseph

2001-12-18

Optical sensor, probe and array devices for detecting chemical biological, and physical analytes. The devices include an analyte-sensitive layer optically coupled to a thin film electroluminescent layer which activates the analyte-sensitive layer to provide an optical response. The optical response varies depending upon the presence of an analyte and is detected by a photodetector and analyzed to determine the properties of the analyte.

Preliminary results on complex ceramic layers deposition by atmospheric plasma spraying

NASA Astrophysics Data System (ADS)

Florea, Costel; Bejinariu, Costicǎ; Munteanu, Corneliu; Cimpoeşu, Nicanor

2017-04-01

In this article we obtain thin layers from complex ceramic powders using industrial equipment based on atmospheric plasma spraying. We analyze the influence of the substrate material roughness on the quality of the thin layers using scanning electron microscopy (SEM) and X-ray dispersive energy analyze (EDAX). Preliminary results present an important dependence between the surface state and the structural and chemical homogeneity.

Solution processed metal oxide thin film hole transport layers for high performance organic solar cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Steirer, K. Xerxes; Berry, Joseph J.; Chesin, Jordan P.

2017-01-10

A method for the application of solution processed metal oxide hole transport layers in organic photovoltaic devices and related organic electronics devices is disclosed. The metal oxide may be derived from a metal-organic precursor enabling solution processing of an amorphous, p-type metal oxide. An organic photovoltaic device having solution processed, metal oxide, thin-film hole transport layer.

Simulation of light in-coupling through an aperture probe to investigate light propagation in a thin layer for opto-electronic application

NASA Astrophysics Data System (ADS)

Ermes, Markus; Lehnen, Stephan; Cao, Zhao; Bittkau, Karsten; Carius, Reinhard

2015-06-01

In thin optoelectronic devices, like organic light emitting diodes (OLED) or thin-film solar cells (TFSC), light propagation, which is initiated by a local point source, is of particular importance. In OLEDs, light is generated in the layer by the luminescence of single molecules, whereas in TFSCs, light is coupled into the devices by scattering at small surface features. In both applications, light propagation within the active layers has a significant impact on the optical device performance. Scanning near-field optical microscopy (SNOM) using aperture probes is a powerful tool to investigate this propagation with a high spatial resolution. Dual-probe SNOM allows simulating the local light generation by an illumination probe as well as the detection of the light propagated through the layer. In our work, we focus on the light propagation in thin silicon films as used in thin-film silicon solar cells. We investigate the light-in-coupling from an illuminating probe via rigorous solution of Maxwell's equations using a Finite-Difference Time-Domain approach, especially to gain insight into the light distribution inside a thin layer, which is not accessible in the experiment. The structures investigated include at and structured surfaces with varying illumination positions and wavelengths. From the performed simulations, we define a "spatial sensitivity" which is characteristic for the local structure and illumination position. This quantity can help to identify structures which are beneficial as well as detrimental to absorption inside the investigated layer. We find a strong dependence of the spatial sensitivity on the surface structure as well as both the absorption coefficient and the probe position. Furthermore, we investigate inhomogeneity in local light propagation resulting from different surface structures and illumination positions.

Relationship of Estimated SHIV Acquisition Time Points During the Menstrual Cycle and Thinning of Vaginal Epithelial Layers in Pigtail Macaques.

PubMed

Kersh, Ellen N; Ritter, Jana; Butler, Katherine; Ostergaard, Sharon Dietz; Hanson, Debra; Ellis, Shanon; Zaki, Sherif; McNicholl, Janet M

2015-12-01

HIV acquisition in the female genital tract remains incompletely understood. Quantitative data on biological HIV risk factors, the influence of reproductive hormones, and infection risk are lacking. We evaluated vaginal epithelial thickness during the menstrual cycle in pigtail macaques (Macaca nemestrina). This model previously revealed increased susceptibility to vaginal infection during and after progesterone-dominated periods in the menstrual cycle. Nucleated and nonnucleated (superficial) epithelial layers were quantitated throughout the menstrual cycle of 16 macaques. We examined the relationship with previously estimated vaginal SHIVSF162P3 acquisition time points in the cycle of 43 different animals repeatedly exposed to low virus doses. In the luteal phase (days 17 to cycle end), the mean vaginal epithelium thinned to 66% of mean follicular thickness (days 1-16; P = 0.007, Mann-Whitney test). Analyzing 4-day segments, the epithelium was thickest on days 9 to 12 and thinned to 31% thereof on days 29 to 32, with reductions of nucleated and nonnucleated layers to 36% and 15% of their previous thickness, respectively. The proportion of animals with estimated SHIV acquisition in each cycle segment correlated with nonnucleated layer thinning (Pearson r = 0.7, P < 0.05, linear regression analysis), but not nucleated layer thinning (Pearson r = 0.6, P = 0.15). These data provide a detailed picture of dynamic cycle-related changes in the vaginal epithelium of pigtail macaques. Substantial thinning occurred in the superficial, nonnucleated layer, which maintains the vaginal microbiome. The findings support vaginal tissue architecture as susceptibility factor for infection and contribute to our understanding of innate resistance to SHIV infection.

Fabrication technology of CNT-Nickel Oxide based planar pseudocapacitor for MEMS and NEMS

NASA Astrophysics Data System (ADS)

Lebedev, E. A.; Kitsyuk, E. P.; Gavrilin, I. M.; Gromov, D. G.; Gruzdev, N. E.; Gavrilov, S. A.; Dronov, A. A.; Pavlov, A. A.

2015-11-01

Fabrication technology of planar pseudocapacitor (PsC) based on carbon nanotube (CNT) forest, synthesized using plasma enhanced chemical vapor deposition (PECVD) method, covered with thin nickel oxide layer deposited by successive ionic layer adsorption and reaction (SILAR) method, is demonstrated. Dependences of deposited oxide layers thickness on device specific capacities is studied. It is shown that pseudocapacity of nickel oxide thin layer increases specific capacity of the CNT's based device up to 2.5 times.

Durable thin film coatings for reflectors used in low earth orbit

NASA Technical Reports Server (NTRS)

Mcclure, Donald J.

1989-01-01

This paper discusses the properties of thin film coatings used to provide a durable reflective surface for solar concentrators used in the solar dynamic system designed for the Space Station. The material system to be used consists of an adhesion promotion layer, a silver reflective layer, and a protective layer of aluminum oxide and silicon dioxide. The performance characteristics of this system are described and compared to those of several alternative systems which use aluminum as the reflective layer.

Temperature dependence of LRE-HRE-TM thin films

NASA Astrophysics Data System (ADS)

Li, Zuoyi; Cheng, Xiaomin; Lin, Gengqi; Li, Zhen; Huang, Zhixin; Jin, Fang; Wang, Xianran; Yang, Xiaofei

2003-04-01

Temperature dependence of the properties of RE-TM thin films is very important for MO recording. In this paper, we studied the temperature dependence of the magnetic and magneto-optical properties of the amorphous LRE-HRE-TM single layer thin films and LRE-HRE-TM/HRE-TM couple-bilayered thin films. For LRE-HRE-TM single layer thin films, the temperature dependence of the magnetization was investigated by using the mean field theory. The experimental and theoretical results matched very well. With the LRE substitution in HRE-TM thin film, the compensation temperature Tcomp decreased and the curie temperature Tc remained unchanged. Kerr rotation angle became larger and the saturation magnetization Ms at room temperature increased. For LRE-HRE-TM/HRE-TM couple-bilayered thin films, comparisons of the temperature dependences of the coercivities and Kerr rotation angles were made between isolated sublayers and couple-bilayered thin film.

Functionalized bioinspired microstructured optical fiber pores for applications in chemical vapor sensing

NASA Astrophysics Data System (ADS)

Calkins, Jacob A.

Chemical vapor sensing for defense, homeland security, environmental, and agricultural application is a challenge, which due combined requirements of ppt sensitivity, high selectivity, and rapid response, cannot be met using conventional analytical chemistry techniques. New sensing approaches and platforms are necessary in order to make progress in this rapidly evolving field. Inspired by the functionalized nanopores on moth sensilla hairs that contribute to the high selectivity and sensitivity of this biological system, a chemical vapor sensor based on the micro to nanoscale pores in microstructured optical fibers (MOFs) was designed. This MOF based chemical vapor sensor design utilizes MOF pores functionalized with organic self-assembled monolayers (SAMs) for selectivity and separations and a gold plasmonic sensor for detection and discrimination. Thin well-controlled gold films in MOF pores are critical components for the fabrication of structured plasmonic chemical vapor sensors. Thermal decomposition of dimethyl Au(II) trifluoroacetylacetonate dissolved in near-critical CO2 was used to deposit gold island films within the MOF pores. Using a 3mercatopropyltrimethoxysilane adhesion layer, continuous gold thin films as thin as 20--30 nm were deposited within MOF pores as small as 500 nm in diameter. The gold island films proved to be SERS active and were used to detect 900 ppt 2,4 DNT vapor in high pressure nitrogen and 6 ppm benzaldehyde. MOF based waveguide Raman (WGR), which can probe the air/silica interface between a waveguiding core and surrounding pores, was developed to detect and characterize SAMs and other thin films deposited in micro to nanoscale MOF pores. MOF based WGR was used to characterize an octadecyltrichlorosilane (OTS) SAM deposited in 1.6 mum diameter pores iv to demonstrate that the SAM was well-formed, uniform along the pore length, and only a single layer. MOF based WGR was used to detect a human serum albumin monolayer deposited on the OTS SAM and monitor in-situ the combustion of an OTS SAM in high pressure oxygen. Light scattering, an optical characterization technique that provides ellipsometric data from micro to nanoscale cylinders, was developed in order to characterize highly smooth wires and MOF pores. Clean, bare gold wires etched from MOF pore templates were found to have angle dependent Psi and Delta values that agree with numerically calculated and finite element modeled values over the full angular 340° collection range. Light scattering was shown to be sensitive to ellipticities in the cross-section of silica, gold, and silicon wires down to 1%. Using alkanethiol SAMs deposited on gold wires, light scattering was demonstrated to be able to detect films as thin as 1.5 nm, and able to distinguish between a decanethiol (1.5 nm) and an octadecanethiol SAM (2.7 mn). The high sensitivity of light scattering will allow it to characterize SAMs and thin films on the inner surfaces of MOF pores. WGR and light scattering provide the analytical tools that will allow for the further development of organic SAMs and thin films within MOF pores for analyte selectivity and chromatographic separations. This high selectivity combined with the sensitivity of a 3-dimensional nanostructured gold plasmonic sensor allows for the fabrication of a chemical vapor sensor inspired by the field performance of moth sensilla hairs.

Preventing Thin Film Dewetting via Graphene Capping.

PubMed

Cao, Peigen; Bai, Peter; Omrani, Arash A; Xiao, Yihan; Meaker, Kacey L; Tsai, Hsin-Zon; Yan, Aiming; Jung, Han Sae; Khajeh, Ramin; Rodgers, Griffin F; Kim, Youngkyou; Aikawa, Andrew S; Kolaczkowski, Mattew A; Liu, Yi; Zettl, Alex; Xu, Ke; Crommie, Michael F; Xu, Ting

2017-09-01

A monolayer 2D capping layer with high Young's modulus is shown to be able to effectively suppress the dewetting of underlying thin films of small organic semiconductor molecule, polymer, and polycrystalline metal, respectively. To verify the universality of this capping layer approach, the dewetting experiments are performed for single-layer graphene transferred onto polystyrene (PS), semiconducting thienoazacoronene (EH-TAC), gold, and also MoS 2 on PS. Thermodynamic modeling indicates that the exceptionally high Young's modulus and surface conformity of 2D capping layers such as graphene and MoS 2 substantially suppress surface fluctuations and thus dewetting. As long as the uncovered area is smaller than the fluctuation wavelength of the thin film in a dewetting process via spinodal decomposition, the dewetting should be suppressed. The 2D monolayer-capping approach opens up exciting new possibilities to enhance the thermal stability and expands the processing parameters for thin film materials without significantly altering their physical properties. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Advanced Si solid phase crystallization for vertical channel in vertical NANDs

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, Sangsoo; Son, Yong-Hoon; Semiconductor R and D Center, Samsung Electronics Co., Ltd., Hwasung 445-701

The advanced solid phase crystallization (SPC) method using the SiGe/Si bi-layer structure is proposed to obtain high-mobility poly-Si thin-film transistors in next generation vertical NAND (VNAND) devices. During the SPC process, the top SiGe thin film acts as a selective nucleation layer to induce surface nucleation and equiaxial microstructure. Subsequently, this SiGe thin film microstructure is propagated to the underlying Si thin film by epitaxy-like growth. The initial nucleation at the SiGe surface was clearly observed by in situ transmission electron microscopy (TEM) when heating up to 600 °C. The equiaxial microstructures of both SiGe nucleation and Si channel layers weremore » shown in the crystallized bi-layer plan-view TEM measurements. Based on these experimental results, the large-grained and less-defective Si microstructure is expected to form near the channel region of each VNAND cell transistor, which may improve the electrical characteristics.« less

Irradiation of industrial enzyme preparations. II. Characterization of fungal pectinase by thin-layer isoelectric focusing and gel filtration

DOE Office of Scientific and Technical Information (OSTI.GOV)

Delincee, H.

1978-01-01

Industrial dry fungal pectinase from A. niger was irradiated with doses (up to 1 Mrad) of /sup 60/Co-..gamma..rays effective in reducing microbial contamination. The pectinase was characterized by thin-layer isoelectric focusing and gel filtration in order to detect possible radiation-induced structural alterations. Thin-layer isoelectric focusing revealed at least fifteen multiple forms with pectin-depolymerizing activity, with isoelectric points in the range pH 4.5 to 7. Heterogeneity of pectinesterase was also demonstrated, the main band occurring around pH 4. By thin-layer gel filtration the molecular weight of the pectin-depolymerase was estimated as being about 36,000, and that of pectinesterase as about 33,000.more » Radiation-induced changes of the charge properties or molecular size of the irradiated pectinase preparation were not observed. The feasibility of using ionizing radiation for the reduction of microbial contamination of industrial enzyme preparations looks promising.« less

Stencil lithography of superconducting contacts on MBE-grown topological insulator thin films

NASA Astrophysics Data System (ADS)

Schüffelgen, Peter; Rosenbach, Daniel; Neumann, Elmar; Stehno, Martin P.; Lanius, Martin; Zhao, Jialin; Wang, Meng; Sheehan, Brendan; Schmidt, Michael; Gao, Bo; Brinkman, Alexander; Mussler, Gregor; Schäpers, Thomas; Grützmacher, Detlev

2017-11-01

Topological insulator (Bi0.06Sb0.94)2Te3 thin films grown by molecular beam epitaxy have been capped in-situ with a 2 nm Al film to conserve the pristine topological surface states. Subsequently, a shadow mask - structured by means of focus ion beam - was in-situ placed underneath the sample to deposit a thick layer of Al on well-defined microscopically small areas. The 2 nm thin Al layer fully oxidizes after exposure to air and in this way protects the TI surface from degradation. The thick Al layer remains metallic underneath a 3-4 nm thick native oxide layer and therefore serves as (super-) conducting contacts. Superconductor-Topological Insulator-Superconductor junctions with lateral dimensions in the nm range have then been fabricated via an alternative stencil lithography technique. Despite the in-situ deposition, transport measurements and transmission electron microscope analysis indicate a low transparency, due to an intermixed region at the interface between topological insulator thin film and metallic Al.

Method and apparatus for stable silicon dioxide layers on silicon grown in silicon nitride ambient

NASA Technical Reports Server (NTRS)

Cohen, R. A.; Wheeler, R. K. (Inventor)

1974-01-01

A method and apparatus for thermally growing stable silicon dioxide layers on silicon is disclosed. A previously etched and baked silicon nitride tube placed in a furnace is used to grow the silicon dioxide. First, pure oxygen is allowed to flow through the tube to initially coat the inside surface of the tube with a thin layer of silicon dioxide. After the tube is coated with the thin layer of silicon dioxide, the silicon is oxidized thermally in a normal fashion. If the tube becomes contaminated, the silicon dioxide is etched off thereby exposing clean silicon nitride and then the inside of the tube is recoated with silicon dioxide. As is disclosed, the silicon nitride tube can also be used as the ambient for the pyrolytic decomposition of silane and ammonia to form thin layers of clean silicon nitride.

Oxide-based materials by atomic layer deposition

NASA Astrophysics Data System (ADS)

Godlewski, Marek; Pietruszka, Rafał; Kaszewski, Jarosław; Witkowski, Bartłomiej S.; Gierałtowska, Sylwia; Wachnicki, Łukasz; Godlewski, Michał M.; Slonska, Anna; Gajewski, Zdzisław

2017-02-01

Thin films of wide band-gap oxides grown by Atomic Layer Deposition (ALD) are suitable for a range of applications. Some of these applications will be presented. First of all, ALD-grown high-k HfO2 is used as a gate oxide in the electronic devices. Moreover, ALD-grown oxides can be used in memory devices, in transparent transistors, or as elements of solar cells. Regarding photovoltaics (PV), ALD-grown thin films of Al2O3 are already used as anti-reflection layers. In addition, thin films of ZnO are tested as replacement of ITO in PV devices. New applications in organic photovoltaics, electronics and optoelectronics are also demonstrated Considering new applications, the same layers, as used in electronics, can also find applications in biology, medicine and in a food industry. This is because layers of high-k oxides show antibacterial activity, as discussed in this work.

Method for the manufacture of phase shifting masks for EUV lithography

DOEpatents

Stearns, Daniel G.; Sweeney, Donald W.; Mirkarimi, Paul B.; Barty, Anton

2006-04-04

A method for fabricating an EUV phase shift mask is provided that includes a substrate upon which is deposited a thin film multilayer coating that has a complex-valued reflectance. An absorber layer or a buffer layer is attached onto the thin film multilayer, and the thickness of the thin film multilayer coating is altered to introduce a direct modulation in the complex-valued reflectance to produce phase shifting features.

Thin film buried anode battery

DOEpatents

Lee, Se-Hee [Lakewood, CO; Tracy, C Edwin [Golden, CO; Liu, Ping [Denver, CO

2009-12-15

A reverse configuration, lithium thin film battery (300) having a buried lithium anode layer (305) and process for making the same. The present invention is formed from a precursor composite structure (200) made by depositing electrolyte layer (204) onto substrate (201), followed by sequential depositions of cathode layer (203) and current collector (202) on the electrolyte layer. The precursor is subjected to an activation step, wherein a buried lithium anode layer (305) is formed via electroplating a lithium anode layer at the interface of substrate (201) and electrolyte film (204). The electroplating is accomplished by applying a current between anode current collector (201) and cathode current collector (202).

Development of the α-IGZO/Ag/α-IGZO Triple-Layer Structure Films for the Application of Transparent Electrode

PubMed Central

Chen, Kun-Neng; Yang, Cheng-Fu; Wu, Chia-Ching; Chen, Yu-Hsin

2017-01-01

We investigated the structural, optical, and electrical properties of amorphous IGZO/silver/amorphous IGZO (α-IGZO/Ag/α-IGZO) triple-layer structures that were deposited at room temperature on Eagle XG glass and flexible polyethylene terephthalate substrates through the sputtering method. Thin Ag layers with different thicknesses were inserted between two IGZO layers to form a triple-layer structure. Ag was used because of its lower absorption and resistivity. Field emission scanning electron microscopy measurements of the triple-layer structures revealed that the thicknesses of the Ag layers ranged from 13 to 41 nm. The thickness of the Ag layer had a large effect on the electrical and optical properties of the electrodes. The optimum thickness of the Ag metal thin film could be evaluated according to the optical transmittance, electrical conductivity, and figure of merit of the electrode. This study demonstrates that the α-IGZO/Ag/α-IGZO triple-layer transparent electrode can be fabricated with low sheet resistance (4.2 Ω/□) and high optical transmittance (88.1%) at room temperature without postannealing processing on the deposited thin films. PMID:28772586

Effect of swift heavy ion irradiation on structural and opto-electrical properties of bi-layer CdS-Bi2S3 thin films prepared by solution growth technique at room temperature

NASA Astrophysics Data System (ADS)

Shaikh, Shaheed U.; Siddiqui, Farha Y.; Desale, Deepali J.; Ghule, Anil V.; Singh, Fouran; Kulriya, Pawan K.; Sharma, Ramphal

2015-01-01

CdS-Bi2S3 bi-layer thin films have been deposited by chemical bath deposition method on Indium Tin Oxide glass substrate at room temperature. The as-deposited thin films were annealed at 250 °C in an air atmosphere for 1 h. An air annealed thin film was irradiated using Au9+ ions with the energy of 120 MeV at fluence 5×1012 ions/cm2 using tandem pelletron accelerator. The irradiation induced modifications were studied using X-ray diffraction (XRD), Atomic Force Microscopy (AFM), Raman spectroscopy, UV spectroscopy and I-V characteristics. XRD study reveals that the as-deposited thin films were nanocrystalline in nature. The decrease in crystallite size, increase in energy band gap and resistivity were observed after irradiation. Results are explained on the basis of energy deposited by the electronic loss after irradiation. The comparative results of as-deposited, air annealed and irradiated CdS-Bi2S3 bi-layer thin films are presented.

Contact interaction of thin-walled elements with an elastic layer and an infinite circular cylinder under torsion

NASA Astrophysics Data System (ADS)

Kanetsyan, E. G.; Mkrtchyan, M. S.; Mkhitaryan, S. M.

2018-04-01

We consider a class of contact torsion problems on interaction of thin-walled elements shaped as an elastic thin washer – a flat circular plate of small height – with an elastic layer, in particular, with a half-space, and on interaction of thin cylindrical shells with a solid elastic cylinder, infinite in both directions. The governing equations of the physical models of elastic thin washers and thin circular cylindrical shells under torsion are derived from the exact equations of mathematical theory of elasticity using the Hankel and Fourier transforms. Within the framework of the accepted physical models, the solution of the contact problem between an elastic washer and an elastic layer is reduced to solving the Fredholm integral equation of the first kind with a kernel representable as a sum of the Weber–Sonin integral and some integral regular kernel, while solving the contact problem between a cylindrical shell and solid cylinder is reduced to a singular integral equation (SIE). An effective method for solving the governing integral equations of these problems are specified.

Effect of dead layer and strain on diffuse phase transition of PLZT relaxor thin films.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tong, S.; Narayanan, M.; Ma, B.

2011-02-01

Bulk relaxor ferroelectrics exhibit excellent permittivity compared to their thin film counterpart, although both show diffuse phase transition (DPT) behavior unlike normal ferroelectrics. To better understand the effect of dead layer and strain on the observed anomaly in the dielectric properties, we have developed relaxor PLZT (lead lanthanum zirconate titanate) thin films with different thicknesses and measured their dielectric properties as a function of temperature and frequency. The effect of dead layer on thin film permittivity has been found to be independent of temperature and frequency, and is governed by the Schottky barrier between the platinum electrode and PLZT. Themore » total strain (thermal and intrinsic) in the film majorly determines the broadening, dielectric peak and temperature shift in the relaxor ferroelectric. The Curie-Weiss type law for relaxors has been further modified to incorporate these two effects to accurately predict the DPT behavior of thin film and bulk relaxor ferroelectrics. The dielectric behavior of thin film is predicted by using the bulk dielectric data from literature in the proposed equation, which agree well with the measured dielectric behavior.« less

Epitaxial growth and dielectric properties of Pb0.4Sr0.6TiO3 thin films on (00l)-oriented metallic Li0.3Ni0.7O2 coated MgO substrates

NASA Astrophysics Data System (ADS)

Li, X. T.; Du, P. Y.; Mak, C. L.; Wong, K. H.

2007-06-01

Highly (00l)-oriented Li0.3Ni0.7O2 thin films have been fabricated on (001) MgO substrates by pulsed laser deposition. The Pb0.4Sr0.6TiO3 (PST40) thin film deposited subsequently also shows a significant (00l)-oriented texture. Both the PST40 and Li0.3Ni0.7O2 have good epitaxial behavior. The epitaxial growth of the PST40 thin film is more perfect with the Li0.3Ni0.7O2 buffer layer due to the less distortion in the film. The dielectric tunability of the PST40 thin film with Li0.3Ni0.7O2 buffer layer therefore reaches 70%, which is 75% higher than that without Li0.3Ni0.7O2 buffer layer, and the dielectric loss of the PST40 thin film is 0.06.

Methods to induce perpendicular magnetic anisotropy in full-Heusler Co2FeSi thin layers in a magnetic tunnel junction structure

NASA Astrophysics Data System (ADS)

Shinohara, Koki; Suzuki, Takahiro; Takamura, Yota; Nakagawa, Shigeki

2018-05-01

In this study, to obtain perpendicular magnetic tunnel junctions (p-MTJs) using half-metallic ferromagnets (HMFs), several methods were developed to induce perpendicular magnetic anisotropy (PMA) in full-Heusler Co2FeSi (CFS) alloy thin layers in an MTJ multilayer composed of a layered CFS/MgO/CFS structure. Oxygen exposure at 2.0 Pa for 10 min after deposition of the bottom CFS layer was effective for obtaining PMA in the CFS layer. One of the reasons for the PMA is the formation of nearly ideal CFS/MgO interfaces due to oxygen exposure before the deposition of the MgO layer. The annealing process was effective for obtaining PMA in the top CFS layer capped with a Pd layer. PMA was clearly observed in the top CFS layer of a Cr(40 nm)/Pd(50 nm)/bottom CFS(0.6 nm)/MgO(2.0 nm)/top CFS(0.6 nm)/ Pd(10 nm) multilayer, where the top CFS and Pd thin films were deposited at RT and subsequently annealed at 300°C. In addition to the continuous layer growth of the films, the crystalline orientation alignment at the top CFS/Pd interface probably attributes to the origin of PMA at the top CFS layer.

Highly improved photo-induced bias stability of sandwiched triple layer structure in sol-gel processed fluorine-doped indium zinc oxide thin film transistor

NASA Astrophysics Data System (ADS)

Kim, Dongha; Park, Hyungjin; Bae, Byeong-Soo

2016-03-01

In order to improve the reliability of TFT, an Al2O3 insulating layer is inserted between active fluorine doped indium zinc oxide (IZO:F) thin films to form a sandwiched triple layer. All the thin films were fabricated via low-cost sol-gel process. Due to its large energy bandgap and high bonding energy with oxygen atoms, the Al2O3 layer acts as a photo-induced positive charge blocking layer that effectively blocks the migration of both holes and V o2+ toward the interface between the gate insulator and the semiconductor. The inserted Al2O3 triple layer exhibits a noticeably low turn on voltage shift of -0.7 V under NBIS as well as the good TFT performance with a mobility of 10.9 cm2/V ṡ s. We anticipate that this approach can be used to solve the stability issues such as NBIS, which is caused by inescapable oxygen vacancies.

High temperature superconductor step-edge Josephson junctions using Ti-Ca-Ba-Cu-O

DOEpatents

Ginley, David S.; Hietala, Vincent M.; Hohenwarter, Gert K. G.; Martens, Jon S.; Plut, Thomas A.; Tigges, Chris P.; Vawter, Gregory A.; Zipperian, Thomas E.

1994-10-25

A process for formulating non-hysteretic and hysteretic Josephson junctions using HTS materials which results in junctions having the ability to operate at high temperatures while maintaining high uniformity and quality. The non-hysteretic Josephson junction is formed by step-etching a LaAlO.sub.3 crystal substrate and then depositing a thin film of TlCaBaCuO on the substrate, covering the step, and forming a grain boundary at the step and a subsequent Josephson junction. Once the non-hysteretic junction is formed the next step to form the hysteretic Josephson junction is to add capacitance to the system. In the current embodiment, this is accomplished by adding a thin dielectric layer, LaA1O.sub.3, followed by a cap layer of a normal metal where the cap layer is formed by first depositing a thin layer of titanium (Ti) followed by a layer of gold (Au). The dielectric layer and the normal metal cap are patterned to the desired geometry.

Triangular Black Phosphorus Atomic Layers by Liquid Exfoliation.

PubMed

Seo, Soonjoo; Lee, Hyun Uk; Lee, Soon Chang; Kim, Yooseok; Kim, Hyeran; Bang, Junhyeok; Won, Jonghan; Kim, Youngjun; Park, Byoungnam; Lee, Jouhahn

2016-03-30

Few-layer black phosphorus (BP) is the most promising material among the two-dimensional materials due to its layered structure and the excellent semiconductor properties. Currently, thin BP atomic layers are obtained mostly by mechanical exfoliation of bulk BP, which limits applications in thin-film based electronics due to a scaling process. Here we report highly crystalline few-layer black phosphorus thin films produced by liquid exfoliation. We demonstrate that the liquid-exfoliated BP forms a triangular crystalline structure on SiO2/Si (001) and amorphous carbon. The highly crystalline BP layers are faceted with a preferred orientation of the (010) plane on the sharp edge, which is an energetically most favorable facet according to the density functional theory calculations. Our results can be useful in understanding the triangular BP structure for large-area applications in electronic devices using two-dimensional materials. The sensitivity and selectivity of liquid-exfoliated BP to gas vapor demonstrate great potential for practical applications as sensors.

Triangular Black Phosphorus Atomic Layers by Liquid Exfoliation

PubMed Central

Seo, Soonjoo; Lee, Hyun Uk; Lee, Soon Chang; Kim, Yooseok; Kim, Hyeran; Bang, Junhyeok; Won, Jonghan; Kim, Youngjun; Park, Byoungnam; Lee, Jouhahn

2016-01-01

Few-layer black phosphorus (BP) is the most promising material among the two-dimensional materials due to its layered structure and the excellent semiconductor properties. Currently, thin BP atomic layers are obtained mostly by mechanical exfoliation of bulk BP, which limits applications in thin-film based electronics due to a scaling process. Here we report highly crystalline few-layer black phosphorus thin films produced by liquid exfoliation. We demonstrate that the liquid-exfoliated BP forms a triangular crystalline structure on SiO2/Si (001) and amorphous carbon. The highly crystalline BP layers are faceted with a preferred orientation of the (010) plane on the sharp edge, which is an energetically most favorable facet according to the density functional theory calculations. Our results can be useful in understanding the triangular BP structure for large-area applications in electronic devices using two-dimensional materials. The sensitivity and selectivity of liquid-exfoliated BP to gas vapor demonstrate great potential for practical applications as sensors. PMID:27026070

Structural properties and sensing performance of high-k Nd2TiO5 thin layer-based electrolyte-insulator-semiconductor for pH detection and urea biosensing.

PubMed

Pan, Tung-Ming; Lin, Jian-Chi; Wu, Min-Hsien; Lai, Chao-Sung

2009-05-15

For high sensitive pH sensing, an electrolyte-insulator-semiconductor (EIS) device with Nd(2)TiO(5) thin layers fabricated on Si substrates by means of reactive sputtering and the subsequent post-deposition annealing (PDA) treatment was proposed. In this work, the effect of thermal annealing (600, 700, 800, and 900 degrees C) on the structural characteristics of Nd(2)TiO(5) thin layer was investigated by X-ray diffraction, X-ray photoelectron spectroscopy, and atomic force microscopy. The observed structural properties were then correlated with the resulting pH sensing performances. For enzymatic field-effect-transistors-based urea biosensing, a hybrid configuration of the proposed Nd(2)TiO(5) thin layer with urease-immobilized alginate film attached was established. Within the experimental conditions investigated, the EIS device with the Nd(2)TiO(5) thin layer annealed at 800 degrees C exhibited a higher pH detection sensitivity of 57.2 mV/pH, a lower hysteresis voltage of 2.33 mV, and a lower drift rate of 1.80 mV/h compared to those at other annealing temperatures. These results are attributed to the formation of a thinner low-k interfacial layer at the oxide/Si interface and the higher surface roughness occurred at this annealing temperature. Furthermore, the presented urea biosensor was also proved to be able to detect urea with good linearity (R(2)=0.99) and reasonable sensitivity of 9.52 mV/mM in the urea concentration range of 3-40 mM. As a whole, the present work has provided some fundamental data for the use of Nd(2)TiO(5) thin layer for EIS-based pH detection and the extended application for biosensing.

Epitaxial thin films

DOEpatents

Hunt, Andrew Tye; Deshpande, Girish; Lin, Wen-Yi; Jan, Tzyy-Jiuan

2006-04-25

Epitatial thin films for use as buffer layers for high temperature superconductors, electrolytes in solid oxide fuel cells (SOFC), gas separation membranes or dielectric material in electronic devices, are disclosed. By using CCVD, CACVD or any other suitable deposition process, epitaxial films having pore-free, ideal grain boundaries, and dense structure can be formed. Several different types of materials are disclosed for use as buffer layers in high temperature superconductors. In addition, the use of epitaxial thin films for electrolytes and electrode formation in SOFCs results in densification for pore-free and ideal gain boundary/interface microstructure. Gas separation membranes for the production of oxygen and hydrogen are also disclosed. These semipermeable membranes are formed by high-quality, dense, gas-tight, pinhole free sub-micro scale layers of mixed-conducting oxides on porous ceramic substrates. Epitaxial thin films as dielectric material in capacitors are also taught herein. Capacitors are utilized according to their capacitance values which are dependent on their physical structure and dielectric permittivity. The epitaxial thin films of the current invention form low-loss dielectric layers with extremely high permittivity. This high permittivity allows for the formation of capacitors that can have their capacitance adjusted by applying a DC bias between their electrodes.