Waste Minimization in Circuit Board Manufacturing by PARMOD(TM) Technology

DTIC Science & Technology

1998-06-24

a foil package in air or in a plastic syringe. Thermogravimetric Analysis (TGA) Ink samples were evaluated using thermogravimetric analysis in...DTA Differential Thermal Analysis FEP Fluorinated Ethylene Propylene (Teflon®) FTIR Fourier Transform Infrared spectroscopy MOD Metallo-Organic...Decomposition ROM Reactive Organic Medium SEM Scanning Electron Microscopy TGA Thermal Gravimetry Analysis Torr Unit of pressure (one mm mercury

Medium Caliber Lead-Free Electric Primer. Version 2

DTIC Science & Technology

2012-09-01

Toxic Substance Control Act TGA Thermogravimetric Analysis TNR Trinitroresorcinol V Voltage VDC Voltage Direct Current WSESRB Weapons System...variety of techniques including Thermogravimetric Analysis (TGA), base-hydrolysis, Surface Area Analysis using Brunauer, Emmett, Teller (BET...Distribution From Thermogravimetric Analysis Johnson, C. E.; Fallis, S.; Chafin, A. P.; Groshens, T. J.; Higa, K. T.; Ismail, I. M. K. and Hawkins, T. W

Sample preparation for thermo-gravimetric determination and thermo-gravimetric characterization of refuse derived fuel.

PubMed

Robinson, T; Bronson, B; Gogolek, P; Mehrani, P

2016-02-01

Thermo-gravimetric analysis (TGA) is a useful method for characterizing fuels. In the past it has been applied to the study of refuse derived fuel (RDF) and related materials. However, the heterogeneity of RDF makes the preparation of small representative samples very difficult and this difficulty has limited the effectiveness of TGA for characterization of RDF. A TGA method was applied to a variety of materials prepared from a commercially available RDF using a variety of procedures. Applicability of TGA method to the determination of the renewable content of RDF was considered. Cryogenic ball milling was found to be an effective means of preparing RDF samples for TGA. When combined with an effective sample preparation, TGA could be used as an alternative method for assessing the renewable content of RDF. Crown Copyright © 2015. Published by Elsevier Ltd. All rights reserved.

Co-gasification of pine and oak biochar with sub-bituminous coal in carbon dioxide.

PubMed

Beagle, E; Wang, Y; Bell, D; Belmont, E

2018-03-01

Pine and oak biochars derived as byproducts of demonstration-scale pyrolysis, and blends of these two feedstocks with Powder River Basin coal, were gasified in a carbon dioxide environment using a modified drop tube reactor (MDTR) and a thermogravimetric analyzer (TGA). The impact of gasification temperature on conversion kinetics was evaluated from the temporal evolution of major product gases in the MDTR as measured using a mass spectrometer. Random pore modeling was conducted to simulate gasification in the MDTR with favorable results. The MDTR and TGA were used to conduct gasification for assessment of non-linear additive effects in the blends. Additive analysis of the blends showed deviation from the experimental blend results, indicating inhibiting effects of co-gasifying the biochar and coal. Inhibitory effects are more significant for oak than pine and more pronounced in the TGA at lower gasification temperatures. Results are discussed in the context of feedstock and reactor type. Copyright © 2017 Elsevier Ltd. All rights reserved.

An increased frequency of patent foramen ovale in patients with transient global amnesia. Analysis of 53 consecutive patients.

PubMed

Klötzsch, C; Sliwka, U; Berlit, P; Noth, J

1996-06-01

Alerted by the number of patients with transient global amnesia (TGA) in whom Valsalvalike activities immediately preceded the onset of TGA, we have investigated the frequency of patent foramen ovale (PFO) as the prerequisite for paradoxical embolism. Case series with comparison to a control group. Hospitalized and ambulatory patients at the neurological departments of the Alfried Krupp Hospital, Essen, Germany, and the Rheinisch-Westfälische-Technische Hochschule, Aachen, Germany. Fifty-three consecutive patients with TGA were evaluated by the 2 centers between 1988 and 1995. Using contrast transcranial Doppler sonography we have observed a PFO in 55% of the patients with TGA, compared with 27% of a control group of 100 patients. This difference was statistically significant (P < .01). Twenty-five patients with TGA (47%), 15 of them with a proven PFO, reported a precipitating activity, such as the lifting of heavy weights, immediately before the TGA occurred. In addition to other pathological mechanisms, paradoxical embolism with temporobasal ischemia could possibly play a role in the clinical syndrome of TGA. This hypothesis could explain the frequent observation of preceding Valsalvalike activities in patients with TGA.

Organizational topology of brain and its relationship to ADHD in adolescents with d-transposition of the great arteries.

PubMed

Schmithorst, Vincent J; Panigrahy, Ashok; Gaynor, J William; Watson, Christopher G; Lee, Vince; Bellinger, David C; Rivkin, Michael J; Newburger, Jane W

2016-08-01

Little is currently known about the impact of congenital heart disease (CHD) on the organization of large-scale brain networks in relation to neurobehavioral outcome. We investigated whether CHD might impact ADHD symptoms via changes in brain structural network topology in a cohort of adolescents with d-transposition of the great arteries (d-TGA) repaired with the arterial switch operation in early infancy and referent subjects. We also explored whether these effects might be modified by apolipoprotein E (APOE) genotype, as the APOE ε2 allele has been associated with worse neurodevelopmental outcomes after repair of d-TGA in infancy. We applied graph analysis techniques to diffusion tensor imaging (DTI) data obtained from 47 d-TGA adolescents and 29 healthy referents to construct measures of structural topology at the global and regional levels. We developed statistical mediation models revealing the respective contributions of d-TGA, APOE genotype, and structural network topology on ADHD outcome as measured by the Connors ADHD/DSM-IV Scales (CADS). Changes in overall network connectivity, integration, and segregation mediated worse ADHD outcomes in d-TGA patients compared to healthy referents; these changes were predominantly in the left and right intrahemispheric regional subnetworks. Exploratory analysis revealed that network topology also mediated detrimental effects of the APOE ε4 allele but improved neurobehavioral outcomes for the APOE ε2 allele. Our results suggest that disruption of organization of large-scale networks may contribute to neurobehavioral dysfunction in adolescents with CHD and that this effect may interact with APOE genotype.

Sleep modifications in acute transient global amnesia.

PubMed

Della Marca, Giacomo; Mazza, Marianna; Losurdo, Anna; Testani, Elisa; Broccolini, Aldobrando; Frisullo, Giovanni; Marano, Giuseppe; Morosetti, Roberta; Pilato, Fabio; Profice, Paolo; Vollono, Catello; Di Lazzaro, Vincenzo

2013-09-15

Transient global amnesia (TGA) is a temporary memory loss characterized by an abrupt onset of antero-grade and retrograde amnesia, totally reversible. Since sleep plays a major role in memory consolidation, and in the storage of memory-related traces into the brain cortex, the aims of the present study were: (1) to evaluate changes in sleep macro-structure in TGA; (2) to assess modifications in sleep micro-structure in TGA, with particular reference to the arousal EEG and to cyclic alternating pattern (CAP); (3) to compare sleep parameters in TGA patients with a control group of patients with acute ischemic events ("minor stroke" or transient ischemic attack [TIA]) clinically and neuroradiologically "similar" to the TGA. TGA GROUP: 17 patients, (8 men and 9 women, 60.2 ± 12.5 years). Stroke or TIA (SoT) group: 17 patients hospitalized in the Stroke Unit for recent onset of minor stroke or TIA with hemispheric localization; healthy controls (HC) group: 17 healthy volunteers, matched for age and sex. Patients and controls underwent full-night polysomnography. In the multivariate analysis (conditions TGA, SoT, and HC) a significant effect of the condition was observed for sleep efficiency index, number of awakenings longer 1 min, REM latency, CAP time, and CAP rate. TGA and SoT differed only for CAP time and CAP rate, which were lower in the TGA group. Microstructural modification associated with tga could be consequent to: (1) hippocampal dysfunction and memory impairment; (2) impairment of arousal-related structures (in particular, cholinergic pathways); (3) emotional distress.

A tandem affinity purification tag of TGA2 for isolation of interacting proteins in Arabidopsis thaliana

PubMed Central

Stotz, Henrik U; Findling, Simone; Nukarinen, Ella; Weckwerth, Wolfram; Mueller, Martin J; Berger, Susanne

2014-01-01

Tandem affinity purification (TAP) tagging provides a powerful tool for isolating interacting proteins in vivo. TAP-tag purification offers particular advantages for the identification of stimulus-induced protein interactions. Type II bZIP transcription factors (TGA2, TGA5 and TGA6) play key roles in pathways that control salicylic acid, ethylene, xenobiotic and reactive oxylipin signaling. Although proteins interacting with these transcription factors have been identified through genetic and yeast 2-hybrid screening, others are still elusive. We have therefore generated a C-terminal TAP-tag of TGA2 to isolate additional proteins that interact with this transcription factor. Three lines most highly expressing TAP-tagged TGA2 were functional in that they partially complemented reactive oxylipin-responsive gene expression in a tga2 tga5 tga6 triple mutant. TAP-tagged TGA2 in the most strongly overexpressing line was proteolytically less stable than in the other 2 lines. Only this overexpressing line could be used in a 2-step purification process, resulting in isolation of co-purifying bands of larger molecular weight than TGA2. TAP-tagged TGA2 was used to pull down NPR1, a protein known to interact with this transcription factor. Mass spectrometry was used to identify peptides that co-purified with TAP-tagged TGA2. Having generated this TGA2 TAP-tag line will therefore be an asset to researchers interested in stimulus-induced signal transduction processes. PMID:25482810

Quantitation of Surface Coating on Nanoparticles Using Thermogravimetric Analysis.

PubMed

Dongargaonkar, Alpana A; Clogston, Jeffrey D

2018-01-01

Nanoparticles are critical components in nanomedicine and nanotherapeutic applications. Some nanoparticles, such as metallic nanoparticles, consist of a surface coating or surface modification to aid in its dispersion and stability. This surface coating may affect the behavior of nanoparticles in a biological environment, thus it is important to measure. Thermogravimetric analysis (TGA) can be used to determine the amount of coating on the surface of the nanoparticle. TGA experiments run under inert atmosphere can also be used to determine residual metal content present in the sample. In this chapter, the TGA technique and experimental method are described.

Thiolate-Capped CdSe/ZnS Core-Shell Quantum Dots for the Sensitive Detection of Glucose.

PubMed

Abd Rahman, Samsulida; Ariffin, Nurhayati; Yusof, Nor Azah; Abdullah, Jaafar; Mohammad, Faruq; Ahmad Zubir, Zuhana; Nik Abd Aziz, Nik Mohd Azmi

2017-07-01

A semiconducting water-soluble core-shell quantum dots (QDs) system capped with thiolated ligand was used in this study for the sensitive detection of glucose in aqueous samples. The QDs selected are of CdSe-coated ZnS and were prepared in house based on a hot injection technique. The formation of ZnS shell at the outer surface of CdSe core was made via a specific process namely, SILAR (successive ionic layer adsorption and reaction). The distribution, morphology, and optical characteristics of the prepared core-shell QDs were assessed by transmission electron microscopy (TEM) and spectrofluorescence, respectively. From the analysis, the results show that the mean particle size of prepared QDs is in the range of 10-12 nm and that the optimum emission condition was displayed at 620 nm. Further, the prepared CdSe/ZnS core shell QDs were modified by means of a room temperature ligand-exchange method that involves six organic ligands, L -cysteine, L -histidine, thio-glycolic acid (TGA or mercapto-acetic acid, MAA), mercapto-propionic acid (MPA), mercapto-succinic acid (MSA), and mercapto-undecanoic acid (MUA). This process was chosen in order to maintain a very dense water solubilizing environment around the QDs surface. From the analysis, the results show that the CdSe/ZnS capped with TGA (CdSe/ZnS-TGA) exhibited the strongest fluorescence emission as compared to others; hence, it was tested further for the glucose detection after their treatment with glucose oxidase (GOx) and horseradish peroxidase (HRP) enzymes. Here in this study, the glucose detection is based on the fluorescence quenching effect of the QDs, which is correlated to the oxidative reactions occurred between the conjugated enzymes and glucose. From the analysis of results, it can be inferred that the resultant GOx:HRP/CdSe/ZnS-TGA QDs system can be a suitable platform for the fluorescence-based determination of glucose in the real samples.

A simple, sensitive graphical method of treating thermogravimetric analysis data

Treesearch

Abraham Broido

1969-01-01

Thermogravimetric Analysis (TGA) is finding increasing utility in investigations of the pyrolysis and combustion behavior of materuals. Although a theoretical treatment of the TGA behavior of an idealized reaction is relatively straight-forward, major complications can be introduced when the reactions are complex, e.g., in the pyrolysis of cellulose, and when...

Electrical and thermal investigations of the phase transition in sodium bicarbonate, NaHCO3

NASA Astrophysics Data System (ADS)

Abdel-Kader, M. M.; Fadly, M.; Abutaleb, M.; El-Tanahy, Z. H.; Eldehemy, K.; Ali, A. I.

1995-09-01

This paper reports on a structural phase transition in sodium hydrogen carbonate, NaHCO3 as revealed by the investigations of some electrical and thermal parameters. Measurements of d.c. electric conductivity (σ) and relative premittivity (epsilon) of polycrystalline samples of NaHCO3 as a function of temperature in the interval 300 < T < 400 K reveal the existence of a structural phase transition around 365 K. Differential thermal analysis (DTA) and thermogravimetric analysis (TGA) were also performed in the same temperature range. The (DTA) results confirm the existence of a structural phase transition at cong 365 K whereas the (TGA) results show the absence of any actual loss in weight in the transition temperature region. The data are correlated to the crystal structure including the hydrogen bonding system.

Modeling of the devolatilization kinetics during pyrolysis of grape residues.

PubMed

Fiori, Luca; Valbusa, Michele; Lorenzi, Denis; Fambri, Luca

2012-01-01

Thermo-gravimetric analysis (TGA) was performed on grape seeds, skins, stalks, marc, vine-branches, grape seed oil and grape seeds depleted of their oil. The TGA data was modeled through Gaussian, logistic and Miura-Maki distributed activation energy models (DAEMs) and a simpler two-parameter model. All DAEMs allowed an accurate prediction of the TGA data; however, the Miura-Maki model could not account for the complete range of conversion for some substrates, while the Gaussian and logistic DAEMs suffered from the interrelation between the pre-exponential factor k0 and the mean activation energy E0--an obstacle that can be overcome by fixing the value of k0 a priori. The results confirmed the capabilities of DAEMs but also highlighted some drawbacks in their application to certain thermodegradation experimental data. Copyright © 2011 Elsevier Ltd. All rights reserved.

Polydimethylsiloxane-based Self healing Composite and Coating Materials

DTIC Science & Technology

2006-01-01

TGA thermogravimetric analysis TDCB tapered double cantilever beam RH relative humidity DMDN-Sn dimethyldineodacanoate tin DBBE-Sn di-n-butyl bis(2...properties of micro-capsules by thermogravimetric analysis (TGA). As shown in figure 2.17, no weight change occurred up to the boiling point of...Elemental analysis of separated prepolymer phase and control samples. ..............24 Table 2.4: The size values of phase separated PDMS droplets

Volatile organic compounds in pesticide formulations: Methods to estimate ozone formation potential

NASA Astrophysics Data System (ADS)

Zeinali, Mazyar; McConnell, Laura L.; Hapeman, Cathleen J.; Nguyen, Anh; Schmidt, Walter F.; Howard, Cody J.

2011-05-01

The environmental fate and toxicity of active ingredients in pesticide formulations has been investigated for many decades, but relatively little research has been conducted on the fate of pesticide co-formulants or inerts. Some co-formulants are volatile organic compounds (VOCs) and can contribute to ground-level ozone pollution. Effective product assessment methods are required to reduce emissions of the most reactive VOCs. Six emulsifiable concentrate pesticide products were characterized for percent VOC by thermogravimetric analysis (TGA) and gas chromatography-mass spectrometry (GC-MS). TGA estimates exceeded GC-MS by 10-50% in all but one product, indicating that for some products a fraction of active ingredient is released during TGA or that VOC contribution was underestimated by GC-MS. VOC profiles were examined using TGA-Fourier transform infrared (FTIR) evolved gas analysis and were compared to GC-MS results. The TGA-FTIR method worked best for products with the simplest and most volatile formulations, but could be developed into an effective product screening tool. An ozone formation potential ( OFP) for each product was calculated using the chemical composition from GC-MS and published maximum incremental reactivity ( MIR) values. OFP values ranged from 0.1 to 3.1 g ozone g -1 product. A 24-h VOC emission simulation was developed for each product assuming a constant emission rate calculated from an equation relating maximum flux rate to vapor pressure. Results indicate 100% VOC loss for some products within a few hours, while other products containing less volatile components will remain in the field for several days after application. An alternate method to calculate a product OFP was investigated utilizing the fraction of the total mass of each chemical emitted at the end of the 24-h simulation. The ideal assessment approach will include: 1) unambiguous chemical composition information; 2) flexible simulation models to estimate emissions under different management practices; and 3) accurate reactivity predictions.

Protein Z efficiently depletes thrombin generation in disseminated intravascular coagulation with poor prognosis.

PubMed

Lee, Nuri; Kim, Ji-Eun; Gu, Ja-Yoon; Yoo, Hyun Ju; Kim, Inho; Yoon, Sung-Soo; Park, Seonyang; Han, Kyou-Sup; Kim, Hyun Kyung

2016-01-01

Disseminated intravascular coagulation (DIC) is characterized by consumption of coagulation factors and anticoagulants. Thrombin generation assay (TGA) gives useful information about global hemostatic status. We developed a new TGA system that anticoagulant addition can deplete thrombin generation in plasma, which may reflect defective anticoagulant system in DIC. TGAs were measured on the calibrated automated thrombogram with and without thrombomodulin or protein Z in 152 patients who were suspected of having DIC, yielding four parameters including lag time, endogenous thrombin potential, peak thrombin and time-to-peak in each experiment. Nonsurvivors showed significantly prolonged lag time and time-to-peak in TGA-protein Z system, which was performed with added protein Z. In multivariate Cox regression analysis, lag time and time-to-peak in TGA system were significant independent prognostic factors. In TGA-protein Z system, lag time and time-to-peak were revealed as independent prognostic factors of DIC. Protein Z addition could potentiate its anticoagulant effect in DIC with poor prognosis, suggesting the presence of defective protein Z system. The prolonged lag time and time-to-peak in both TGA and TGA-protein Z systems are expected to be used as independent prognostic factors of DIC.

Triglycidylamine Crosslinking of Porcine Aortic Valve Cusps or Bovine Pericardium Results in Improved Biocompatibility, Biomechanics, and Calcification Resistance

PubMed Central

Connolly, Jeanne M.; Alferiev, Ivan; Clark-Gruel, Jocelyn N.; Eidelman, Naomi; Sacks, Michael; Palmatory, Elizabeth; Kronsteiner, Allyson; DeFelice, Suzanne; Xu, Jie; Ohri, Rachit; Narula, Navneet; Vyavahare, Narendra; Levy, Robert J.

2005-01-01

We investigated a novel polyepoxide crosslinker that was hypothesized to confer both material stabilization and calcification resistance when used to prepare bioprosthetic heart valves. Triglycidylamine (TGA) was synthesized via reacting epichlorhydrin and NH3. TGA was used to crosslink porcine aortic cusps, bovine pericardium, and type I collagen. Control materials were crosslinked with glutaraldehyde (Glut). TGA-pretreated materials had shrink temperatures comparable to Glut fixation. However, TGA crosslinking conferred significantly greater collagenase resistance than Glut pretreatment, and significantly improved biomechanical compliance. Sheep aortic valve interstitial cells grown on TGA-pretreated collagen did not calcify, whereas sheep aortic valve interstitial cells grown on control substrates calcified extensively. Rat subdermal implants (porcine aortic cusps/bovine pericardium) pretreated with TGA demonstrated significantly less calcification than Glut pretreated implants. Investigations of extracellular matrix proteins associated with calcification, matrix metalloproteinases (MMPs) 2 and 9, tenascin-C, and osteopontin, revealed that MMP-9 and tenascin-C demonstrated reduced expression both in vitro and in vivo with TGA crosslinking compared to controls, whereas osteopontin and MMP-2 expression were not affected. TGA pretreatment of heterograft biomaterials results in improved stability compared to Glut, confers biomechanical properties superior to Glut crosslinking, and demonstrates significant calcification resistance. PMID:15631995

Thermal Properties of Lunar Regolith Simulants

NASA Technical Reports Server (NTRS)

Street, Kenneth W., Jr.; Ray, Chandra; Rickman, Doug; Scheiman, Daniel A.

2010-01-01

Various high temperature chemical processes have been developed to extract oxygen and metals from lunar regolith. These processes are tested using terrestrial analogues of the regolith. But all practical terrestrial analogs contain H2O and/or OH-, the presence of which has substantial impact on important system behaviors. We have undertaken studies of lunar regolith simulants to determine the limits of the simulants to validate key components for human survivability during sustained presence on the Moon. Differential Thermal Analysis (DTA) yields information on phase transitions and melting temperatures. Thermo-Gravimetric Analysis (TGA) with Fourier Transform Infrared (FTIR) analysis provides information on evolved gas species and their evolution temperature profiles. The DTA and TGA studies included JSC-1A fine (Johnson Space Center Mare Type 1A simulant), NU-LHT-2M (National Aeronautics and Space Administration (NASA)-- United States Geological Survey (USGS)--Lunar Highlands Type 2M simulant) and its proposed feedstocks: anorthosite; dunite; high quality (HQ) glass and the norite from which HQ glass is produced. As an example, the DTA and TGA profiles for anorthosite follow. The DTA indicates exothermic transitions at 355 and 490 C and endothermic transitions at 970 and 1235 C. Below the 355 C transition, water is lost accounting for approximately 0.1 percent mass loss. Just above 490 C a second type of water is lost, presumably bound in lattices of secondary minerals along with other volatile oxides. Limited TGA-FTIR data is available at the time of this writing. For JSC-1A fine, the TGA-FTIR indicates at least two kinds of water are evolved in the 100 to 500 and the 700 to 900 C ranges. Evolution of carbon dioxide types occurs in the 250 to 545, 545 to 705, and 705 to 985 C ranges. Geologically, the results are consistent with the evolution of "water" in its several forms, CO2 from break down of secondary carbonates and magmatic, dissolved gas and glass recrystallization

Standardization of Shodhita Naga with special reference to thermogravimetry and infra-red spectroscopy

PubMed Central

Rajput, Dhirajsingh S.; Patgiri, Biswajyoti; Shukla, Vinay J.

2014-01-01

Background: Standardization of Ayurvedic medicine is the need of hour to obtain desired quality of final product. Shodhana literally means purification, is the initial step to make drugs like metals, minerals and poisonous herbs suitable for further procedure. Shodhana of metals/minerals help to expose maximum surface area of drug for chemical reactions and also in impregnation of organic materials and their properties in the drug. Thermo-gravimetric analysis (TGA) facilitates in identifying the presence of organic matter and change in the melting point of metal whereas Fourier transform infra-red spectroscopy (FTIR) assists in identifying the presence of various functional groups. Aim: To standardize the process of Naga Shodhana and to study the change in chemical nature of Shodhita Naga in each media through TGA and FTIR. Material and Methods: Samanya and Vishesha Shodhana of Naga was carried out. Time taken for melting of Naga, physico-chemical changes in media used for Shodhana and weight changes after Shodhana were recorded. Samples of Naga were collected after Shodhana in each media for TGA and FTIR analysis. Results: Average loss occurred during Shodhana was 6.26%. Melting point of Ashuddha Naga was 327.46°C, and it was 328.42°C after Shodhana. Percentage purity of Naga (percentage of lead in Naga) decreased after Shodhana from 99.80% to 99.40%. FTIR analysis of Shodhita Naga in each sample showed stretching vibrations particularly between C-H and C-N bonds that are indicating the presence of various organic compounds. Conclusion: According to TGA and FTIR analysis, Shodhana process increases melting point of Naga and initiation of new physico-chemical properties which are indicated by detection of large number of functional groups and organo-metallic nature of Shodhita Naga. PMID:26664241

Investigation of Water Absorption and Diffusion in Microparticles Containing Xylitol to Provide a Cooling Effect by Thermal Analysis

NASA Astrophysics Data System (ADS)

Salaün, F.; Bedek, G.; Devaux, E.; Dupont, D.; Deranton, D.

2009-08-01

Polyurethane microparticles containing xylitol as a sweat sensor system were prepared by interfacial polymerization. The structural and thermal properties of the resultant microparticles were studied. The surface morphology and chemical structure of microparticles were investigated using an optical microscope (OM) and a Fourier-transform infrared spectroscope (FTIR), respectively. The thermal properties of samples were investigated by thermogravimetric analysis (TGA) and by differential scanning calorimetry (DSC). Thus, two types of microparticles were synthesized by varying the percentage of monomers introduced. The obtained morphology is directly related to the synthesis conditions. DSC analysis indicated that the mass content of crystalline xylitol was up to 63.8 %, which resulted in a high enthalpy of dilution of 127.7 J · g-1. Furthermore, the water release rate monitored by TGA analysis was found to be faster from the microparticles than from raw xylitol. Thus, the microparticles could be applied for thermal energy storage and moisture sensor enhancement.

Thermal: Differential Scanning Calorimetry (DSC), Thermogravimetric Analysis (TGA), and Polarized Microscopy Instrumentation for the Analysis of Field-Controlled Anisotropic Nanomaterials

DTIC Science & Technology

2014-11-14

figure 1.2.1, right). The discovery TGA furnace design employs a silicon carbide ( SiC ) inner chamber. Four halogen lamps surrounded by a water...amplification,(13, 17) self-phase modulation (18, 19), and new nonlinear phenomena such as the nonlinear optical mirror ,(20) and the mirrorless optical

Accuracy in Diagnosis of Celiac Disease Without Biopsies in Clinical Practice.

PubMed

Werkstetter, Katharina Julia; Korponay-Szabó, Ilma Rita; Popp, Alina; Villanacci, Vincenzo; Salemme, Marianna; Heilig, Gabriele; Lillevang, Søren Thue; Mearin, Maria Luisa; Ribes-Koninckx, Carmen; Thomas, Adrian; Troncone, Riccardo; Filipiak, Birgit; Mäki, Markku; Gyimesi, Judit; Najafi, Mehri; Dolinšek, Jernej; Dydensborg Sander, Stine; Auricchio, Renata; Papadopoulou, Alexandra; Vécsei, Andreas; Szitanyi, Peter; Donat, Ester; Nenna, Rafaella; Alliet, Philippe; Penagini, Francesca; Garnier-Lengliné, Hélène; Castillejo, Gemma; Kurppa, Kalle; Shamir, Raanan; Hauer, Almuthe Christine; Smets, Françoise; Corujeira, Susana; van Winckel, Myriam; Buderus, Stefan; Chong, Sonny; Husby, Steffen; Koletzko, Sibylle

2017-10-01

The guidelines of the European Society of Pediatric Gastroenterology, Hepatology, and Nutrition allow for diagnosis of celiac disease without biopsies in children with symptoms and levels of immunoglobulin A against tissue-transglutaminase (TGA-IgA) 10-fold or more the upper limit of normal (ULN), confirmed by detection of endomysium antibodies (EMA) and positivity for HLA-DQ2/DQ8. We performed a large, international prospective study to validate this approach. We collected data from consecutive pediatric patients (18 years or younger) on a gluten-containing diet who tested positive for TGA-IgA from November 2011 through May 2014, seen at 33 pediatric gastroenterology units in 21 countries. Local centers recorded symptoms; measurements of total IgA, TGA, and EMA; and histopathology findings from duodenal biopsies. Children were considered to have malabsorption if they had chronic diarrhea, weight loss (or insufficient gain), growth failure, or anemia. We directly compared central findings from 16 antibody tests (8 for TGA-IgA, 1 for TGA-IgG, 6 for IgG against deamidated gliadin peptides, and 1 for EMA, from 5 different manufacturers), 2 HLA-DQ2/DQ8 tests from 2 manufacturers, and histopathology findings from the reference pathologist. Final diagnoses were based on local and central results. If all local and central results were concordant for celiac disease, cases were classified as proven celiac disease. Patients with only a low level of TGA-IgA (threefold or less the ULN) but no other results indicating celiac disease were classified as no celiac disease. Central histo-morphometry analyses were performed on all other biopsies and cases were carefully reviewed in a blinded manner. Inconclusive cases were regarded as not having celiac disease for calculation of diagnostic accuracy. The primary aim was to determine whether the nonbiopsy approach identifies children with celiac disease with a positive predictive value (PPV) above 99% in clinical practice. Secondary aims included comparing performance of different serological tests and to determine whether the suggested criteria can be simplified. Of 803 children recruited for the study, 96 were excluded due to incomplete data, low level of IgA, or poor-quality biopsies. In the remaining 707 children (65.1% girls; median age, 6.2 years), 645 were diagnosed with celiac disease, 46 were found not to have celiac disease, and 16 had inconclusive results. Findings from local laboratories of TGA-IgA 10-fold or more the ULN, a positive result from the test for EMA, and any symptom identified children with celiac disease (n = 399) with a PPV of 99.75 (95% confidence interval [CI], 98.61-99.99); the PPV was 100.00 (95% CI, 98.68-100.00) when only malabsorption symptoms were used instead of any symptom (n = 278). Inclusion of HLA analyses did not increase accuracy. Findings from central laboratories differed greatly for patients with lower levels of antibodies, but when levels of TGA-IgA were 10-fold or more the ULN, PPVs ranged from 99.63 (95% CI, 98.67-99.96) to 100.00 (95% CI, 99.23-100.00). Children can be accurately diagnosed with celiac disease without biopsy analysis. Diagnosis based on level of TGA-IgA 10-fold or more the ULN, a positive result from the EMA tests in a second blood sample, and the presence of at least 1 symptom could avoid risks and costs of endoscopy for more than half the children with celiac disease worldwide. HLA analysis is not required for accurate diagnosis. Clinical Trial Registration no: DRKS00003555. Copyright © 2017 AGA Institute. Published by Elsevier Inc. All rights reserved.

Flame retardancy and thermal behavior of intumescent flame-retardant EVA composites with an efficient triazine-based charring agent

NASA Astrophysics Data System (ADS)

Xu, Bo; Ma, Wen; Wu, Xiao; Qian, Lijun; Jiang, Shan

2018-04-01

Intumescent flame retardant (IFR) EVA composites were prepared based on a hyperbranched triazine charring-foaming agent (HTCFA) and ammonium polyphosphate (APP). The synergistic effect of HTCFA and APP on the flame retardancy and thermal behavior of the composites were investigated through flammability tests, cone calorimeter measurements, thermogravimetric analysis (TGA) including evolved gas analysis (TG-IR) and residue analysis (Fourier transform infrared (FTIR), laser Raman spectroscopy (LRS), x-ray Photoelectron Spectroscopy (XPS) and scanning electron microscopy (SEM)). The flammability test results showed HTCFA/APP (1/3) system presented the best synergistic effect in flame-retardant EVA composites with the highest LOI value and UL-94 V-0 rating. As for cone calorimeter results, IFR changed the combustion behavior of EVA and resulted in remarkable decrease of flammability and smoke product. TGA results showed the synergistic effect between APP and HTCFA could strengthen the char-forming ability of composites. TG-IR results indicated the melt viscosities and gas release with increasing temperature were well-correlated for EVA/IFR composite. The residue analysis results from SEM, LRS, FT-IR and XPS revealed IFR promoted forming more compact graphitic char layer, connected by rich P–O–C and P–N structures.

Synthesis and Characterization of Mesoporous Silica Functionalized with Calix[4]arene Derivatives

PubMed Central

Alahmadi, Sana M.; Mohamad, Sharifah; Maah, Mohd Jamil

2012-01-01

This work reports a new method to covalently attach calix[4]arene derivatives onto MCM-41, using a diisocyanate as a linker. The modified mesoporous silicates were characterized by fourier transform infrared spectroscopy (FTIR), thermal analysis (TGA) and elemental analysis. The FTIR spectra and TGA analysis verified that the calix[4]arene derivates are covalently attached to the mesoporous silica. The preservation of the MCM-41 channel system was checked by X-ray diffraction and nitrogen adsorption analysis. PMID:23202977

Modifications in the optical and thermal properties of a CR-39 polymeric detector induced by high doses of γ-radiation

NASA Astrophysics Data System (ADS)

Saad, A. F.; Ibraheim, Mona H.; Nwara, Aya M.; Kandil, S. A.

2018-04-01

Effects of γ-radiation on the optical and thermal properties of a poly allyl diglycol carbonate (PADC), a form of CR-39, polymer have been investigated. CR-39 detectors were exposed to γ-rays at very high doses ranging from 5.0 × 105 to 3.0 × 106 Gy. The induced changes were analyzed using ultraviolet-visible spectroscopy (UV-VIS) in absorbance mode, and thermogravimetric analysis (TGA). The UV-visible spectra of the virgin and γ-irradiated CR-39 polymer detectors displayed a significant decreasing trend in their optical energy band gaps for indirect transitions, whereas for the direct ones showed a little change. This drop in the energy band gap with increasing dose is discussed on the basis of the gamma irradiation induced modifications in the CR-39 polymeric detector. The TGA thermograms show that the weight loss rate increased with increase in dose, which may be due to the disordered system via scission followed by crosslinking in the irradiated polymer detector. The TGA thermograms also indicated that the CR-39 detector decomposed in three/four stages for the virgin and irradiated samples. The activation energy for thermal decomposition was determined using a type of Arrhenius equation based on the TGA experimental results. These experimental results so obtained can be well used in radiation dosimetry.

Synthesis of Hydroxyapatite through Ultrasound and Calcination Techniques

NASA Astrophysics Data System (ADS)

Akindoyo, John O.; Beg, M. D. H.; Ghazali, Suriati; Akindoyo, Edward O.; Jeyaratnam, Nitthiyah

2017-05-01

There is a growing demand for hydroxyapatite (HA) especially in medical applications, production of HA which is totally green is however a challenge. In this research, HA was produced from biowaste through ultrasound followed by calcination techniques. Pre-treatment of the biowaste was effectively achieved through the help of ultrasound. After calcination at 950°C, the obtained HA was characterized through Thermogravimetric (TGA) analysis, X-ray diffraction analysis (XRD) and Fourier transform infrared spectroscopy (FTIR). Spectrum of the produced HA was compared with standard HA index. The spectrum is in agreement with the standard HA as confirmed through FTIR, XRD and TGA result. Furthermore, morphological study of the HA through Field emission scanning electron microscope (FESEM) shows almost uniform spherical shape for the HA as expected. Based on the results obtained herein, combining ultrasound with calcination can help to produce pure HA with potential medical applications without the use of any organic solvent.

Oxidation Kinetics and Strength Degradation of Carbon Fibers in a Cracked Ceramic Matrix Composite

NASA Technical Reports Server (NTRS)

Halbig, Michael C.

2003-01-01

Experimental results and oxidation modeling will be presented to discuss carbon fiber susceptibility to oxidation, the oxidation kinetics regimes and composite strength degradation and failure due to oxidation. Thermogravimetric Analysis (TGA) was used to study the oxidation rates of carbon fiber and of a pyro-carbon interphase. The analysis was used to separately obtain activation energies for the carbon constituents within a C/SiC composite. TGA was also conducted on C/SiC composite material to study carbon oxidation and crack closure as a function of temperature. In order to more closely match applications conditions C/SiC tensile coupons were also tested under stressed oxidation conditions. The stressed oxidation tests show that C/SiC is much more susceptible to oxidation when the material is under an applied load where the cracks are open and allow for oxygen ingress. The results help correlate carbon oxidation with composite strength reduction and failure.

Insertion of Guest Molecules into a Mixed Ligand Metal-Organic Framework via Single-Crystal-to-Single Crystal Guest Exchange

DTIC Science & Technology

2014-07-01

powder x-ray diffraction (PXRD), thermogravimentric analysis (TGA), and Fourier transform infrared (FTIR). 15. SUBJECT TERMS Metal organic frame work...the inclusion by using a variety of analytical techniques, such as powder x-ray diffraction (PXRD), thermo-gravimetric analysis (TGA), Fourier...Characterizations Analysis of the MOF and the complexes with the MOF and the guest molecules was performed using an Agilent GC-MS (Model 6890N GC and Model 5973N

Thiolated polymers--thiomers: development and in vitro evaluation of chitosan-thioglycolic acid conjugates.

PubMed

Kast, C E; Bernkop-Schnürch, A

2001-09-01

The aim of this study was to improve mucoadhesive properties of chitosan by the covalent attachment of thiol moieties to this cationic polymer. Mediated by a carbodiimide, thioglycolic acid (TGA) was covalently attached to chitosan. This was achieved by the formation of amide bonds between the primary amino groups of the polymer and the carboxylic acid group of TGA. Dependent on the pH-value and the weight ratio of polymer to TGA during the coupling reaction the resulting thiolated polymers, the so-called thiomers, displayed 6.58, 9.88, 27.44, and 38.23 micromole thiol groups per gram polymer. Tensile studies carried out with these chitosan-TGA conjugates on freshly excised porcine intestinal mucosa demonstrated a 6.3-, 8.6-, 8.9-, and 10.3-fold increase in the total work of adhesion (TWA) compared to the unmodified polymer, respectively. In contrast, the combination of chitosan and free unconjugated TGA showed almost no mucoadhesion. These data were in good correlation with further results obtained by another mucoadhesion test demonstrating a prolonged residence time of thiolated chitosan on porcine mucosa. The swelling behavior of all conjugates was thereby exactly in the same range as for an unmodified polymer pretreated in the same way. Furthermore, it could be shown that chitosan-TGA conjugates are still biodegradable by the glycosidase lysozyme. According to these results. chitosan-TGA conjugates represent a promising tool for the development of mucoadhesive drug delivery systems.

Photo and Thermal Behavior of New Reinforced Polyamide-nanocomposite Montmorillonite on 2,3-Pyrazin Dicarboxylic Acid

NASA Astrophysics Data System (ADS)

Faghihi, Khalil; Samiei, Mojtaba; Hajibeygi, Mohsen

2012-06-01

Two new samples of reinforce polyamidemontmorillonite nanocomposites were synthesized by a convenient solution intercalation technique. Polyamide (PA) 3 as a source of polymer matrix was synthesized by the direct polycondensation reaction of pyrazine 2,3-dicarboxylic acid 1 with 4,4'-diamino diphenyl ether 2 in the presence of triphenyl phosphite (TPP), CaCl2, pyridine and N-methyl-2-pyrrolidone (NMP). The resulting nanocomposite films were characterized by Fourier transform infrared spectra (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM) and thermogravimetric analysis (TGA). The results showed that organo-modified clay was dispersed homogeneously in PA matrix. TGA indicated an enhancement of thermal stability of new nanocomposites compared with the pure polymer.

Determination of microplastic polyethylene (PE) and polypropylene (PP) in environmental samples using thermal analysis (TGA-DSC).

PubMed

Majewsky, Marius; Bitter, Hajo; Eiche, Elisabeth; Horn, Harald

2016-10-15

Microplastics are increasingly detected in the environment and the consequences on water resources and ecosystems are not clear to date. The present study provides a cost-effective and straightforward method to determine the mass concentrations of polymer types using thermal analysis. Characteristic endothermic phase transition temperatures were determined for seven plastic polymer types using TGA-DSC. Based on that, extracts from wastewater samples were analyzed. Results showed that among the studied polymers, only PE and PP could be clearly identified, while the phase transition signals of the other polymers largely overlap each other. Subsequently, calibration curves were run for PE and PP for qualitative measurements. 240 and 1540mg/m(3) of solid material (12µm to 1mm) was extracted from two wastewater effluent samples of a municipal WWTP of which 34% (81mg/m(3)) and 17% (257mg/m(3)) could be assigned to PE, while PP was not detected in any of the samples. The presented application of TGA-DSC provides a complementary or alternative method to FT-IR analyses for the determination of PE and PP in environmental samples. Copyright © 2016 Elsevier B.V. All rights reserved.

Quantitative detection of powdered activated carbon in wastewater treatment plant effluent by thermogravimetric analysis (TGA).

PubMed

Krahnstöver, Therese; Plattner, Julia; Wintgens, Thomas

2016-09-15

For the elimination of potentially harmful micropollutants, powdered activated carbon (PAC) adsorption is applied in many wastewater treatment plants (WWTP). This holds the risk of PAC leakage into the WWTP effluent and desorption of contaminants into natural water bodies. In order to assess a potential PAC leakage, PAC concentrations below several mg/L have to be detected in the WWTP effluent. None of the methods that are used for water analysis today are able to differentiate between activated carbon and solid background matrix. Thus, a selective, quantitative and easily applicable method is still needed for the detection of PAC residues in wastewater. In the present study, a method was developed to quantitatively measure the PAC content in wastewater by using filtration and thermogravimetric analysis (TGA), which is a well-established technique for the distinction between different solid materials. For the sample filtration, quartz filters with a temperature stability up to 950 °C were used. This allowed for sensitive and well reproducible measurements, as the TGA was not affected by the presence of the filter. The sample's mass fractions were calculated by integrating the mass decrease rate obtained by TGA in specific, clearly identifiable peak areas. A two-step TGA heating method consisting of N2 and O2 atmospheres led to a good differentiation between PAC and biological background matrix, thanks to the reduction of peak overlapping. A linear correlation was found between a sample's PAC content and the corresponding peak areas under N2 and O2, the sample volume and the solid mass separated by filtration. Based on these findings, various wastewater samples from different WWTPs were then analyzed by TGA with regard to their PAC content. It was found that, compared to alternative techniques such as measurement of turbidity or total suspended solids, the newly developed TGA method allows for a quantitative and selective detection of PAC concentrations down to 0.1 mg/L. The method showed a linearity coefficient of 0.98 and relative standard deviations of 10%, using small water sample volumes between 0.3 and 0.6 L. Copyright © 2016 Elsevier Ltd. All rights reserved.

Abnormal EEG Power Spectra in Acute Transient Global Amnesia: A Quantitative EEG Study.

PubMed

Imperatori, Claudio; Farina, Benedetto; Todini, Federico; Di Blasi, Chiara; Mazzucchi, Edoardo; Brunetti, Valerio; Della Marca, Giacomo

2018-06-01

Transient global amnesia (TGA) is a clinical syndrome characterized by retrograde and anterograde amnesia without other neurological deficits. Although electroencephalography (EEG) methods are commonly used in both clinical and research setting with TGA patients, few studies have investigated neurophysiological pattern in TGA using quantitative EEG (qEEG). The main aim of the present study was to extend these previous findings by exploring EEG power spectra differences between patients with acute TGA and healthy controls using the exact low-resolution brain electromagnetic tomography software (eLORETA). EEG was recorded during 5 minutes of resting state. Sixteen patients (mean age: 66.81 ± 7.94 years) during acute TGA and 16 healthy subjects were enrolled. All patients showed hippocampal or parahippocampal signal abnormalities in diffusion-weighted magnetic resonance imaging performed from 2 to 5 days after the onset of TGA. Compared with healthy controls, TGA patients showed a decrease of theta power localized in the temporal lobe (Brodmann areas, BAs 21-22-38) and frontal lobe (BAs 8-9-44-45). A decrease of EEG beta power in the bilateral precuneus (BA 7) and in the bilateral postcentral gyrus (BAs 3-4-5) was also observed in TGA individuals. Taken together, our results could reflect the neurophysiological substrate of the severe impairment of both episodic memory and autobiographical memory which affect TGA patients during the acute phase.

Cloning and Functional Analysis of the Promoter of an Ascorbate Oxidase Gene from Gossypium hirsutum

PubMed Central

Xin, Shan; Tao, Chengcheng; Li, Hongbin

2016-01-01

Apoplastic ascorbate oxidase (AO) plays significant roles in plant cell growth. However, the mechanism of underlying the transcriptional regulation of AO in Gossypium hirsutum remains unclear. Here, we obtained a 1,920-bp promoter sequence from the Gossypium hirsutum ascorbate oxidase (GhAO1) gene, and this GhAO1 promoter included a number of known cis-elements. Promoter activity analysis in overexpressing pGhAO1::GFP-GUS tobacco (Nicotiana benthamiana) showed that the GhAO1 promoter exhibited high activity, driving strong reporter gene expression in tobacco trichomes, leaves and roots. Promoter 5’-deletion analysis demonstrated that truncated GhAO1 promoters with serial 5’-end deletions had different GUS activities. A 360-bp fragment was sufficient to activate GUS expression. The P-1040 region had less GUS activity than the P-720 region, suggesting that the 320-bp region from nucleotide -720 to -1040 might include a cis-element acting as a silencer. Interestingly, an auxin-responsive cis-acting element (TGA-element) was uncovered in the promoter. To analyze the function of the TGA-element, tobacco leaves transformed with promoters with different 5’ truncations were treated with indole-3-acetic acid (IAA). Tobacco leaves transformed with the promoter regions containing the TGA-element showed significantly increased GUS activity after IAA treatment, implying that the fragment spanning nucleotides -1760 to -1600 (which includes the TGA-element) might be a key component for IAA responsiveness. Analyses of the AO promoter region and AO expression pattern in Gossypium arboreum (Ga, diploid cotton with an AA genome), Gossypium raimondii (Gr, diploid cotton with a DD genome) and Gossypium hirsutum (Gh, tetraploid cotton with an AADD genome) indicated that AO promoter activation and AO transcription were detected together only in D genome/sub-genome (Gr and Gh) cotton. Taken together, these results suggest that the 1,920-bp GhAO1 promoter is a functional sequence with a potential effect on fiber cell development, mediated by TGA-element containing sequences, via the auxin-signaling pathway. PMID:27597995

Cloning and Functional Analysis of the Promoter of an Ascorbate Oxidase Gene from Gossypium hirsutum.

PubMed

Xin, Shan; Tao, Chengcheng; Li, Hongbin

2016-01-01

Apoplastic ascorbate oxidase (AO) plays significant roles in plant cell growth. However, the mechanism of underlying the transcriptional regulation of AO in Gossypium hirsutum remains unclear. Here, we obtained a 1,920-bp promoter sequence from the Gossypium hirsutum ascorbate oxidase (GhAO1) gene, and this GhAO1 promoter included a number of known cis-elements. Promoter activity analysis in overexpressing pGhAO1::GFP-GUS tobacco (Nicotiana benthamiana) showed that the GhAO1 promoter exhibited high activity, driving strong reporter gene expression in tobacco trichomes, leaves and roots. Promoter 5'-deletion analysis demonstrated that truncated GhAO1 promoters with serial 5'-end deletions had different GUS activities. A 360-bp fragment was sufficient to activate GUS expression. The P-1040 region had less GUS activity than the P-720 region, suggesting that the 320-bp region from nucleotide -720 to -1040 might include a cis-element acting as a silencer. Interestingly, an auxin-responsive cis-acting element (TGA-element) was uncovered in the promoter. To analyze the function of the TGA-element, tobacco leaves transformed with promoters with different 5' truncations were treated with indole-3-acetic acid (IAA). Tobacco leaves transformed with the promoter regions containing the TGA-element showed significantly increased GUS activity after IAA treatment, implying that the fragment spanning nucleotides -1760 to -1600 (which includes the TGA-element) might be a key component for IAA responsiveness. Analyses of the AO promoter region and AO expression pattern in Gossypium arboreum (Ga, diploid cotton with an AA genome), Gossypium raimondii (Gr, diploid cotton with a DD genome) and Gossypium hirsutum (Gh, tetraploid cotton with an AADD genome) indicated that AO promoter activation and AO transcription were detected together only in D genome/sub-genome (Gr and Gh) cotton. Taken together, these results suggest that the 1,920-bp GhAO1 promoter is a functional sequence with a potential effect on fiber cell development, mediated by TGA-element containing sequences, via the auxin-signaling pathway.

Long-term results after atrial correction of complete transposition of the great arteries.

PubMed

Merlo, M; de Tommasi, S M; Brunelli, F; Abbruzzese, P A; Crupi, G; Ghidoni, I; Casari, A; Pitì, A; Mamprin, F; Parenzan, L

1991-02-01

This study presents the late results for the first 104 consecutive patients surviving and atrial repair for transposition of the great arteries (TGA) between January 1971 and December 1978 (group 1). Mean follow-up was 12 years (range, 0.1 to 17.7 years). The actuarial survival rate at 18 years was 84.2% (70% confidence limits, 79% to 88%) for simple TGA and 93.7% (70% confidence limits, 84% to 97%) for complex TGA. Nine of the 11 deaths were sudden. Two (2.6%) of the 78 late survivors operated on for simple TGA are in New York Heart Association functional class III or IV versus 4 (26.7%) of the 15 survivors with complex TGA; the other patients are doing very well. To better assess long-term results, we report the findings for randomly obtained electrocardiograms, Holter monitor recordings, radionuclide angiographic studies, and cardiac catheterizations performed in 1987 in a larger group of 159 long-term survivors of atrial repair operated on at Ospedale Riuniti di Bergamo from January 1971 to December 1984 (group 2), which includes all of group 1. The findings confirm that the arterial switch repair is the procedure of choice for complex TGA and that there is a major incidence (approximately 10%) of systemic right ventricular dysfunction and rhythm disturbances after the atrial repair. On the other hand, our late survival rate at 18 years of 84% for simple TGA with 97.5% of the patients in functional class I is a result that should be kept in mind, especially in institutions where the arterial switch is a relatively new approach and presumably is a higher risk to cause early death.

Extraction and physicochemical characterization of chitin and chitosan from Zophobas morio larvae in varying sodium hydroxide concentration.

PubMed

Soon, Chu Yong; Tee, Yee Bond; Tan, Choon Hui; Rosnita, Abdul Talib; Khalina, Abdan

2018-03-01

Large amount of sodium hydroxide (NaOH) is consumed to remove the protein content in chitin biomass during deproteinization. However, excessive NaOH concentration used might lead to the reduction of cost effectiveness during chitin extraction. Hence, the present study aimed to extract and evaluate the physicochemical properties of chitin and chitosan isolated from superworm (Zophobas morio) larvae using 0.5M-2.0M of NaOH. The extracted chitin and chitosan were subjected to Fourier Transform Infrared Spectroscopy (FT-IR), elemental analysis, Scanning Electron Microscope (SEM), Thermogravimetric Analysis (TGA), Differential Scanning Calorimetry (DSC) and X-ray Diffraction (XRD). The 0.5M NaOH treatment resulted in the highest yield of chitin (5.43%), but produced the lowest yield (65.84%) of chitosan. The extracted chitin samples had relatively high degree of acetylation (DA) (82.39%-101.39%). Both chitin and chitosan showed smooth surface with tiny pores. The extracted chitin samples were confirmed as α-chitin based on the FT-IR and TGA. The chitin samples were amorphous with low degree of crystallinity. From TGA, the Chitosan 3 extracted was partially deacetylated. Both DPPH radical scavenging and ferric-chelating assay showed positive correlation with DD of chitosan isolates. However, the chitosan isolates were not fully dissolved, resulting in lower radical scavenging and ferric-chelating ability compared to commercial chitosan. Copyright © 2017. Published by Elsevier B.V.

Medicine shortages in Australia: causes, impact and management strategies in the community setting.

PubMed

Tan, Yee Xi; Moles, Rebekah J; Chaar, Betty B

2016-10-01

Background Medicine shortages are an ongoing global problem. The Therapeutic Goods Administration (TGA) dedicated a website for monitoring of medicine shortages in Australia in May 2014, as part of the Medicine Shortage Information Initiative. This study aimed to explore the views of pharmacists regarding medicine shortages in the community setting and the impact of the TGA website in Australia. Setting Community pharmacies in New South Wales, Australia. Method Twenty semi-structured interviews were conducted with community pharmacists. Data collected were analysed thematically utilising the framework analysis method. Main outcome measure Qualitative analysis conducted using the framework approach. Results Findings clearly indicated that medicine shortages were experienced on a regular basis, but most participants were unaware of the TGA website. Medicine shortages reportedly impacted both pharmacists and consumers; and various workarounds were undertaken to manage the issue. The "price disclosure policy" was found to be a prominent contributing factor in emerging shortages. Suggestions were made for ways to improve the growing occurrence of shortages. Conclusion Overall, the study found that there was a lack of familiarity with the TGA website, despite experiencing regular shortages of medicines in practice. Also highlighted, was the importance of pharmacists prioritising patient care over business decisions. To reduce prescribing of out-of-stock medicines notifying doctors about shortages was also considered important, to allow for early action to be taken at higher levels of the supply chain. Findings of this study may help direct future policy-making around the world, as medicine shortages is a problem shared by healthcare providers in most countries around the world.

Development of a Portable Sensitive Equipment Decontamination System. Volume 2: Activated Carbon Fiber Wipe

DTIC Science & Technology

2010-05-01

absorption. Thermogravimetric Analysis (TGA) was employed to measure absorption of HD and GD into the nylon fabric. TGA is an analytical tool useful in...Chromatography Analysis 26 4.4.5.1 Mass Removed by Wiper at Room Temperature 26 4.4.6 Chemical Agent Mass Removed by Wiper at Elevated and Reduced...Temperature Tests 71 5.9 Vapor Analysis of Spent Wipe 78 5.10 Wiping Efficacy and Complex Geometries 82 5.11 Spray and Wipe Tests 84 5.12 Effect of

A new optically transparent silicon containing polyimide film

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

Kumar, D.; Gupta, A.D.

1995-12-31

A new optically transparent, heat-resistant, flexible silicon containing polyimide (PI)(SIDA-BAPB) film has been developed. It was characterized by UV-Visible, FT-IR, differential scanning calorimetery (DSC), thermomechanical analysis (TMA) and thermogravimetric (TGA) analysis. The developed film showed high optical transparency in the 350-600 nm range of electromagnetic spectrum. The DSC analysis of the film showed glass transition temperature (T{sub g}) at 200{degrees}C. The dynamic thermogravimetric analysis (TGA) demonstrated its polymer decomposition temperature at 425{degrees}C. The char yield of the amorphous film in nitrogen at 800{degrees}C was 61%.

Thermal behaviour and corrosion resistance of nano-ZnO/polyurethane film

NASA Astrophysics Data System (ADS)

Virgawati, E.; Soegijono, B.

2018-03-01

Hybrid materials Nano-ZnO/polyurethane film was prepared with different zinc oxide (ZnO) content in polyurethane as a matrix. The film was deposited on low carbon steel plate using high volume low pressure (HVLP) method. To observe thermal behaviour of the film, the sample was investigated using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). Fourier transform infrared spectroscopy (FTIR) was used to see whether any chemical reaction of ZnO in polyurethane occured. TGA and FTIR results showed that the decomposition temperature shifted to a higher point and the chemical reaction of zinc oxide in polyurethane occurred. The surface morphology changed and the corrosion resistance increased with an increase of ZnO content

Control of the shape and size of iron oxide (α-Fe2O3) nanoparticles synthesized through the chemical precipitation method

NASA Astrophysics Data System (ADS)

Lassoued, Abdelmajid; Dkhil, Brahim; Gadri, Abdellatif; Ammar, Salah

Hematite (α-Fe2O3) nanoparticles were synthesized via a simple chemical precipitation method. The impact of varying the concentration of precursor on the crystalline phase, size and morphology of α-Fe2O3 products was explored. The characteristic of the synthesized hematite nanoparticles were evaluated by X-ray diffraction (XRD), Transmission Electron Microscopy (TEM), Scanning Electron Microscopy (SEM), Fourier Transform Infra-Red (FT-IR) spectroscopy, Raman spectroscopy, Differential Thermal Analysis (DTA), Thermo Gravimetric Analysis (TGA), Ultraviolet-Visible (UV-Vis) analysis and Photoluminescence (PL). XRD data revealed a rhombohedral (hexagonal) structure with the space group R-3c in all samples. Uniform spherical like morphology was confirmed by TEM and SEM. The result revealed that the particle sizes were varied between 21 and 82 nm and that the increase in precursor concentration (FeCl3, 6H2O) is accompanied by an increase in the particle size of 21 nm for pure α-Fe2O3 synthesized with [Fe3+] = 0.05 M at 82 nm for pure α-Fe2O3 synthesized with [Fe3+] = 0.4 M. FT-IR confirms the phase purity of the nanoparticles synthesized. The Raman spectroscopy was used not only to prove that we have synthesized pure hematite but also to identify their phonon modes. The thermal behavior of compound was studied by using TGA/DTA results: The TGA showed three mass losses, whereas DTA resulted in three endothermic peaks. Besides, the optical investigation revealed that samples have an optical gap of about 2.1 eV and that this value varies as a function of the precursor concentration.

Comparison of systemic right ventricular function in transposition of the great arteries after atrial switch and congenitally corrected transposition of the great arteries.

PubMed

Morcos, Michael; Kilner, Philip J; Sahn, David J; Litt, Harold I; Valsangiacomo-Buechel, Emanuela R; Sheehan, Florence H

2017-12-01

In patients with transposition of the great arteries corrected by interatrial baffle (TGA) and those with congenitally corrected transposition of the great arteries (ccTGA) the right ventricle (RV) is subjected to systemic pressure and fails prematurely. Previous studies have demonstrated RV dysfunction may be more pronounced in patients with TGA. The present study sought to compare patients with TGA and ccTGA using three-dimensional (3D) techniques to comprehensively analyze the shape, volume, global and regional function in the systemic RV. We compared RV size, shape, and regional and global function in 25 patients with TGA, 17 patients with ccTGA, and 9 normal subjects. The RVs were reconstructed from cardiac Magnetic Resonance Images for 3D analyses. Compared to normal, the RV in TGA and ccTGA was dilated, rounded, and reduced in function. Compared to each other, TGA and ccTGA patients had similar RV size and shape. Global RV function was lower in TGA than ccTGA when assessed from ejection fraction (EF) (30 ± 7 vs. 35 ± 7, p = 0.02) and from normalized tricuspid annular systolic plane excursion (TAPSE) (0.10 ± 0.04 vs. 0.18 ± 0.04, p < 0.01). Basilar RV function was poorer in the TGA patients when compared to ccTGA. The systemic RVs in both TGA and ccTGA are dilated, spherical, and poorly functioning. Compared to ccTGA, TGA RVs have reduced TAPSE and worse basilar hypokinesis.

Preparation of hyperbranched poly (amidoamine)-grafted graphene nanolayers as a composite and curing agent for epoxy resin

NASA Astrophysics Data System (ADS)

Gholipour-Mahmoudalilou, Meysam; Roghani-Mamaqani, Hossein; Azimi, Reza; Abdollahi, Amin

2018-01-01

Thermal properties of epoxy resin were improved by preparation of a curing agent of poly (amidoamine) (PAMAM) dendrimer-grafted graphene oxide (GO). Hyperbranched PAMAM-modified GO (GD) was prepared by a divergent dendrimer synthesis methodology. Modification of GO with (3-Aminopropyl)triethoxysilane (APTES), Michael addition of methacrylic acid, and amidation reaction with ethylenediamine results in the curing agent of GD. Then, epoxy resin was cured in the presence of different amounts of GD and the final products were compared with ethylenediamine-cured epoxy resin (E) in their thermal degradation temperature and char contents. Functionalization of GO with APTES and hyperbranched dendrimer formation at the surface of GO were evaluated by Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction, and thermogravimetric analysis (TGA) results. TGA results showed that the weight loss associated with chemical moieties in GONH2, GOMA, and GD is estimated to be 10.1, 12.2, and 14.1%, respectively. Covalent attachment of dendrimer at the surface of GO increases its thermal stability. TGA also showed that decomposition temperature and char content are higher for composites compared with E. Scanning and transmission electron microscopies show that flat and smooth graphene nanolayers are wrinkled in GO and re-stacking and flattening of nanolayers is observed in GD.

The role of teosinte glume architecture (tga1) in coordinated regulation and evolution of grass glumes and inflorescence axes.

PubMed

Preston, Jill C; Wang, Huai; Kursel, Lisa; Doebley, John; Kellogg, Elizabeth A

2012-01-01

• Hardened floral bracts and modifications to the inflorescence axis of grasses have been hypothesized to protect seeds from predation and/or aid seed dispersal, and have evolved multiple times independently within the family. Previous studies have demonstrated that mutations in the maize (Zea mays ssp. mays) gene teosinte glume architecture (tga1) underlie a reduction in hardened structures, yielding free fruits that are easy to harvest. It remains unclear whether the causative mutation(s) occurred in the cis-regulatory or protein-coding regions of tga1, and whether similar mutations in TGA1-like genes can explain variation in the dispersal unit in related grasses. • To address these questions TGA1-like genes were cloned and sequenced from a number of grasses and analyzed phylogenetically in relation to morphology; protein expression was investigated by immunolocalization. • TGA1-like proteins were expressed throughout the spikelet in the early development of all grasses, and throughout the flower of the grass relative Joinvillea. Later in development, expression patterns differed between Tripsacum dactyloides, maize and teosinte (Z. mays ssp. parviglumis). • These results suggest an ancestral role for TGA1-like genes in early spikelet development, but do not support the hypothesis that TGA1-like genes have been repeatedly modified to affect glume and inflorescence axis diversification. © 2011 The Authors. New Phytologist © 2011 New Phytologist Trust.

Glycoalkaloids in potato tubers grown under controlled environments

NASA Technical Reports Server (NTRS)

Nitithamyong, A.; Vonelbe, J. H.; Wheeler, R. M.; Tibbitts, T. W.

1999-01-01

Tuber content of alpha-solanine, alpha-chaconine, and total glycoalkaloids (TGA) was determined for the potato cultivars, Norland, Russet Burbank, and Denali grown under different environmental conditions in growth chambers. The lowest TGA concentrations (0.30 to 0.35 mg g-1 dry tissue) were found in the cv. Norland with 400 micromoles m-2 s-1 photosynthetic photon flux (PPF), 12 h day length, 16 C temperature, and 350 micromoles mol-1 carbon dioxide. The ratio of alpha-chaconine to alpha-solanine was close to 60:40 under all growing conditions, except that it was 50:50 under the low temperature of 12 C. Cultivars responded similarly to environmental conditions although TGA was about 20% greater in cv. Russet Burbank and about 30% greater in Denali compared to Norland. The largest changes in TGA occurred with changes in temperature. In comparison to 16 C, TGA were 40% greater at 12 C, 80% greater at 20 C, and 125% greater at 24 C (0.70 mg g-1 dry weight). The TGA concentration increased from 10 to 25% with an increase in light from 400 to 800 micromoles m-2 s-1 PPF for all three cultivars. TGA increased 20% with extension of the day length from 12 to 24 hr and also increased 20% when carbon dioxide was increased from 350 to 1000 micromoles mol-1. TGA concentrations were not influenced by changes in relative humidity from 50 to 80%. TGA concentrations decreased only slightly in harvests made from 9 to 21 weeks after planting. Variations in TGA among the different growing conditions and cultivars were below 20 mg/100 g fresh weight (approximately 1.0 mg g-1 dry weight) recognized as the upper concentration for food safety. However the results suggest that TGA should be considered when potatoes are grown at temperatures above 20 C.

Age-Related DNA Methylation Changes and Neoplastic Transformation of the Human Prostate

DTIC Science & Technology

2011-07-01

Vol. 4 Issue 1 Figure 4. Methylation and expression analysis of the Sprouty1. (A) Representative program traces for Sprouty1. Gray colums represents...5’-ggt acc CCC TCC TGA GCT CAT GGT AAC CT-3’ Fwd 6 (-509) 5’-ggt acc CTT CTG GTT TGG AGC ACA GTG CAA AG-3’ Fwd 5 (-1318) 5’ggt acc AGA AGA CCT...CCC GAG GTG GAT GTT A-3’ Fwd3 (-2025) 5’-ggt acc CTG TCA ATC ACC GGG AGC-3’ Reverse (+8) 5’-gct agc AAT CCG CAC TGA ATA AAT AGT TGA C-3’. For

In silico cloning and characterization of the TGA (TGACG MOTIF-BINDING FACTOR) transcription factors subfamily in Carica papaya.

PubMed

Idrovo Espín, Fabio Marcelo; Peraza-Echeverria, Santy; Fuentes, Gabriela; Santamaría, Jorge M

2012-05-01

The TGA transcription factors belong to the subfamily of bZIP group D that play a major role in disease resistance and development. Most of the TGA identified in Arabidopsis interact with the master regulator of SAR, NPR1 that controls the expression of PR genes. As a first approach to determine the possible involvement of these transcription factors in papaya defense, we characterized Arabidopsis TGA orthologs from the genome of Carica papaya cv. SunUp. Six orthologs CpTGA1 to CpTGA6, were identified. The predicted CpTGA proteins were highly similar to AtTGA sequences and probably share the same DNA binding properties and transcriptional regulation features. The protein sequences alignment evidenced the presence of conserved domains, characteristic of this group of transcription factors. The phylogeny showed that CpTGA evolved into three different subclades associated with defense and floral development. This is the first report of basal expression patterns assessed by RT-PCR, from the whole subfamily of CpTGA members in different tissues from papaya cv. Maradol mature plants. Overall, CpTGA1, CpTGA3 CpTGA6 and CpTGA4 showed a basal expression in all tissues tested; CpTGA2 expressed strongly in all tissues except in petioles while CpTGA5 expressed only in petals and to a lower extent in petioles. Although more detailed studies in anthers and other floral structures are required, we suggest that CpTGA5 might be tissue-specific, and it might be involved in papaya floral development. On the other hand, we report here for the first time, the expression of the whole family of CpTGA in response to salicylic acid (SA). The expression of CpTGA3, CpTGA4 and CpTGA6 increased in response to SA, what would suggest its involvement in the SAR response in papaya. Copyright © 2012 Elsevier Masson SAS. All rights reserved.

Age at gluten introduction and risk of celiac disease.

PubMed

Aronsson, Carin Andrén; Lee, Hye-Seung; Liu, Edwin; Uusitalo, Ulla; Hummel, Sandra; Yang, Jimin; Hummel, Michael; Rewers, Marian; She, Jin-Xiong; Simell, Olli; Toppari, Jorma; Ziegler, Anette-G; Krischer, Jeffrey; Virtanen, Suvi M; Norris, Jill M; Agardh, Daniel

2015-02-01

The goal of this study was to determine whether age at introduction to gluten was associated with risk for celiac disease (CD) in genetically predisposed children. TEDDY (The Environmental Determinants of Diabetes in the Young) is a prospective birth cohort study. Newborn infants (N = 6436) screened for high-risk HLA-genotypes for CD were followed up in Finland, Germany, Sweden, and the United States. Information about infant feeding was collected at clinical visits every third month. The first outcome was persistent positive for tissue transglutaminase autoantibodies (tTGA), the marker for CD. The second outcome was CD, defined as either a diagnosis based on intestinal biopsy results or on persistently high levels of tTGA. Swedish children were introduced to gluten earlier (median: 21.7 weeks) compared with children from Finland (median: 26.1 weeks), Germany, and the United States (both median: 30.4 weeks) (P < .0001). During a median follow-up of 5.0 years (range: 1.7-8.8 years), 773 (12%) children developed tTGA and 307 (5%) developed CD. Swedish children were at increased risk for tTGA (hazard ratio: 1.74 [95% CI: 1.47-2.06]) and CD (hazard ratio: 1.76 [95% CI: 1.34-2.24]) compared with US children, respectively (P < .0001).Gluten introduction before 17 weeks or later than 26 weeks was not associated with increased risk for tTGA or CD, adjusted for country, HLA, gender, and family history of CD, neither in the overall analysis nor on a country-level comparison. In TEDDY, the time to first introduction to gluten introduction was not an independent risk factor for developing CD. Copyright © 2015 by the American Academy of Pediatrics.

Preparation and characterization of poly(vinyl alcohol)/graphene nanofibers synthesized by electrospinning

NASA Astrophysics Data System (ADS)

Barzegar, Farshad; Bello, Abdulhakeem; Fabiane, Mopeli; Khamlich, Saleh; Momodu, Damilola; Taghizadeh, Fatemeh; Dangbegnon, Julien; Manyala, Ncholu

2015-02-01

We report on the synthesis and characterization of electrospun polyvinyl alcohol (PVA)/graphene nanofibers. The samples produced were characterized by Raman spectroscopy for structural and defect density analysis, scanning electron microscopy (SEM) for morphological analysis, and thermogravimetric (TGA) for thermal analysis. SEM measurements show uniform hollow PVA fibers formation and excellent graphene dispersion within the fibers, while TGA measurements show the improved thermal stability of PVA in the presence of graphene. The synthesized polymer reinforced nanofibers have potential to serve in many different applications such as thermal management, supercapacitor electrodes and biomedical materials for drug delivery.

Thermal properties of Bentonite Modified with 3-aminopropyltrimethoxysilane

NASA Astrophysics Data System (ADS)

Pramono, E.; Pratiwi, W.; Wahyuningrum, D.; Radiman, C. L.

2018-03-01

Chemical modifications of Bentonite (BNT) clay have been carried out by using 3-aminoprophyltrimethoxysilane (APS) in various solvent media. The degradation properties of products (BNTAPS) were characterized by thermogravimetric analysis (TGA). Samples were heated at 30 to 700°C with a heating rate 10 deg/min, and the total silane-grafted amount was determined by calculating the weight loss at 200 – 600°C. The thermogram of TGA showed that there were three main decomposition regions which are attributed to the elimination of physically adsorbed water, decomposition of silane and dehydroxylation of Bentonite. High weight loss attributed to the thermal decomposition of silane was observed between 200 to 550°C. Quantitative analysis of grafted silane results high silane loaded using a solvent with high surface energy, which indicates the type of solvent affected interaction and adsorption of APS in BNT platelets.

Thermal properties of polyethylene reinforced with recycled–poly (ethylene terephthalate) flakes.

NASA Astrophysics Data System (ADS)

Ruqiyah Nik Hassan, Nik; Mazni Ismail, Noor; Ghazali, Suriati; Nuruzzaman, Dewan Muhammad

2018-04-01

In this study, recycled plastic bottles (RPET) were used as a filler in high density polyethylene (HDPE) thermoplastic. The plastic sheet of RPET/HDPE was prepared by using hot and cold press machine. The effects of RPET addition and hot press process to the thermal properties of the composite RPET/HDPE were investigated using differential scanning calorimetry (DSC) and thermogravimetric (TGA). Results from DSC analysis show that the melting point of HDPE slightly shifted to a higher temperature for about 2°C to 4°C with the addition of RPET as a filler. The starting degradation temperature of RPET/HDPE composite examined from TGA analysis also seen to be slightly increased. It was observed that the incorporation of recycled PET flakes into HDPE is achievable using hot press process with slight improvement seen in both melting point and thermal stability of the composite compared to the neat HDPE.

Kinetics and evolved gas analysis for pyrolysis of food processing wastes using TGA/MS/FT-IR.

PubMed

Özsin, Gamzenur; Pütün, Ayşe Eren

2017-06-01

The objective of this study was to identify the pyrolysis of different bio-waste produced by food processing industry in a comprehensible manner. For this purpose, pyrolysis behaviors of chestnut shells (CNS), cherry stones (CS) and grape seeds (GS) were investigated by thermogravimetric analysis (TGA) combined with a Fourier-transform infrared (FT-IR) spectrometer and a mass spectrometer (MS). In order to make available theoretical groundwork for biomass pyrolysis, activation energies were calculated with the help of four different model-free kinetic methods. The results are attributed to the complex reaction schemes which imply parallel, competitive and complex reactions during pyrolysis. During pyrolysis, the evolution of volatiles was also characterized by FT-IR and MS. The main evolved gases were determined as H 2 O, CO 2 and hydrocarbons such as CH 4 and temperature dependent profiles of the species were obtained. Copyright © 2017 Elsevier Ltd. All rights reserved.

Kinetics of the pyrolysis of arundo, sawdust, corn stover and switch grass biomass by thermogravimetric analysis using a multi-stage model.

PubMed

Biney, Paul O; Gyamerah, Michael; Shen, Jiacheng; Menezes, Bruna

2015-03-01

A new multi-stage kinetic model has been developed for TGA pyrolysis of arundo, corn stover, sawdust and switch grass that accounts for the initial biomass weight (W0). The biomass were decomposed in a nitrogen atmosphere from 23°C to 900°C in a TGA at a single 20°C/min ramp rate in contrast with the isoconversion technique. The decomposition was divided into multiple stages based on the absolute local minimum values of conversion derivative, (dx/dT), obtained from DTG curves. This resulted in three decomposition stages for arundo, corn stover and sawdust and four stages for switch grass. A linearized multi-stage model was applied to the TGA data for each stage to determine the pre-exponential factor, activation energy, and reaction order. The activation energies ranged from 54.7 to 60.9 kJ/mol, 62.9 to 108.7 kJ/mol, and 18.4 to 257.9 kJ/mol for the first, second and the third decomposition stages respectively. Copyright © 2014 Elsevier Ltd. All rights reserved.

Combustion characteristics of Malaysian oil palm biomass, sub-bituminous coal and their respective blends via thermogravimetric analysis (TGA).

PubMed

Idris, Siti Shawalliah; Rahman, Norazah Abd; Ismail, Khudzir

2012-11-01

The combustion characteristics of Malaysia oil palm biomass (palm kernel shell (PKS), palm mesocarp fibre (PMF) and empty fruit bunches (EFB)), sub-bituminous coal (Mukah Balingian) and coal/biomass blends via thermogravimetric analysis (TGA) were investigated. Six weight ratios of coal/biomass blends were prepared and oxidised under dynamic conditions from temperature 25 to 1100°C at four heating rates. The thermogravimetric analysis demonstrated that the EFB and PKS evolved additional peak besides drying, devolatilisation and char oxidation steps during combustion. Ignition and burn out temperatures of blends were improved in comparison to coal. No interactions were observed between the coal and biomass during combustion. The apparent activation energy during this process was evaluated using iso-conversional model free kinetics which resulted in highest activation energy during combustion of PKS followed by PMF, EFB and MB coal. Blending oil palm biomass with coal reduces the apparent activation energy value. Copyright © 2012 Elsevier Ltd. All rights reserved.

Electrospinning of PVC with natural rubber

NASA Astrophysics Data System (ADS)

Othman, Muhammad Hariz; Mohamed, Mahathir; Abdullah, Ibrahim

2013-11-01

Polyvinyl chloride (PVC) was mixed with natural rubbers which are liquid natural rubber (LNR), liquid epoxidised natural rubber (LENR) and liquid epoxidised natural rubber acrylate (LENRA) for a preparation of a fine non-woven fiber's mat. PVC and each natural rubbers(PVC:LENR, PVC:LNR and PVC:LENRA) were mixed based on ratio of 70:30. Electrospinning method was used to prepare the fiber. The results show that the spinnable concentration of PVC/ natural rubber/THF solution is 16 wt%. The morphology, diameter, structure and degradation temperature of electrospun fibers were investigated by scanning electron microscopy (SEM) and thermogravimetric analysis (TGA). SEM photos showed that the morphology and diameter of the fibers were mainly affected by the addition of natural rubber. TGA results suggested that PVC electrospun fiber has higher degradation temperature than those electrospun fibers that contain natural rubber.

New Poly(amide-imide)/Nanocomposites Reinforced Silicate Nanoparticles Based on N-pyromellitimido-L-phenyl Alanine Containing Ether Moieties

NASA Astrophysics Data System (ADS)

Faghihi, Khalil; Shabanian, Meisam; Dadfar, Ehsan

2012-02-01

A series of Poly(amide-imide)/montmorillonite nanocomposites containing N-pyromellitimido-L-phenyl alanine moiety in the main chain were synthesized by a convenient solution intercalation technique. Poly(amide-imide) (PAI) 5 as a source of polymer matrix was synthesized by the direct polycondensation reaction of N-pyromellitimido-L-phenyl alanine 3 with 4,4'-diamino diphenyl ether 4 in the presence of triphenyl phosphite (TPP), CaCl2, pyridine and N-methyl-2-pyrrolidone (NMP). The resulting nanocomposite films were characterized by Fourier transform infrared spectra (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM) and thermogravimetric analysis (TGA). The results showed that organo-modified clay was dispersed homogeneously in PAI matrix. TGA indicated an enhancement of thermal stability of new nanocomposites compared with the pure polymer.

Fullerene carbon-70 derivatives dampen anaphylaxis and allergic asthma pathogenesis in mice

NASA Astrophysics Data System (ADS)

Norton, Sarah Brooke

Fullerenes are carbon nanospheres that can be solublized by the addition of polar chemical groups to the carbon cage, forming fullerene derivatives. One specifically derivatized fullerene compound, termed C 70-Tetragylocolate (C70-TGA), has been shown to stabilize mast cell responses in vitro thus we hypothesized it may have an effect on mast cell-driven diseases such as asthma and systemic anaphylaxis. To observe the effects of C70-TGA on systemic anaphylaxis, mice were subjected to a model of passive systemic anaphylaxis. In this model, mice were injected with DNP-specific IgE 16 hours prior to challenge, then treated with C 70-TGA. Immediately prior to DNP challenge, mice were subjected to a second injection of C70-TGA. Following DNP challenge, body temperature was recorded and blood was collected for quantitation of histamine levels. Treatment with C70-TGA significantly reduced body temperature drop associated with systemic anaphylaxis and serum histamine levels. To observe the effects of C70-TGA on chronic features of asthma in vivo, we utilized a heavily MC influenced model of asthma pathogenesis. Mice were sensitized by intraperitoneal (i.p.) injection of ovalbumin (OVA) in saline, challenged intranasally (i.n.) with OVA, and one of two treatment strategies was pursued. In one, C70-TGA was given i.n. throughout disease development. In the other, C70-TGA was given following an initial set of challenges to allow disease to develop prior to treatment; mice were then re-challenged with OVA to assess the effect on established disease. We found that C70-TGA treatment significantly reduced airway inflammation and eosinophilia and dramatically reduced bronchoconstriction in either model. Cytokines IL-4 and IL-5 and serum IgE levels are significantly reduced in C70-TGA treated animals. Interestingly, we also saw an increase in the anti-inflammatory eicosanoid 11, 12-epoxyeicosatreinoic acid (11,12-EET) in the BAL fluid, suggesting the involvement of this mediator in C70-TGA inhibition. Further experiments utilizing an inhibitor of 11,12-EET formation (6-(2-Propargyloxyphenyl)hexanoic acid) and a structural analog of 14,15-EET (14,15-EE-5(Z)-E) in vivo indicate that these mediators are closely associated with C70-TGA mediated inhibition as their inhibition reverses the anti-inflammatory effects of C70-TGA. Importantly, mice did not exhibit any acute toxicity following C70-TGA treatment and liver and kidney function were normal. Collectively, these results show that the fullerene C70 derivative C70-TGA is capable of dampening severe allergic responses including systemic anaphylaxis, airway inflammation, and bronchoconstriction. The mechanism of inhibition is through the upregulation of the anti-inflammatory EETs, which may dampen mast cell degranulation in vivo, thus contributing to the inhibitory effect of C70-TGA on allergic disease

Thermogravimetric and differential thermal analysis of potassium bicarbonate contaminated cellulose

Treesearch

A. Broido

1966-01-01

When samples undergo a complicated set of simultaneous and sequential reactions, as cellulose does on heating, results of thermogravimetric and differential thermal analyses are difficult to interpret. Nevertheless, careful comparison of pure and contaminated samples, pyrolyzed under identical conditions, can yield useful information. In these experiments TGA and DTA...

Thermal decomposition kinetics of hydrazinium cerium 2,3-Pyrazinedicarboxylate hydrate: a new precursor for CeO2.

PubMed

Premkumar, Thathan; Govindarajan, Subbiah; Coles, Andrew E; Wight, Charles A

2005-04-07

The thermal decomposition kinetics of N(2)H(5)[Ce(pyrazine-2,3-dicarboxylate)(2)(H(2)O)] (Ce-P) have been studied by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC), for the first time; TGA analysis reveals an oxidative decomposition process yielding CeO(2) as the final product with an activation energy of approximately 160 kJ mol(-1). This complex may be used as a precursor to fine particle cerium oxides due to its low temperature of decomposition.

Working memory and executive functions in transient global amnesia.

PubMed

Quinette, Peggy; Guillery, Bérengère; Desgranges, Béatrice; de la Sayette, Vincent; Viader, Fausto; Eustache, Francis

2003-09-01

Transient global amnesia (TGA) is usually considered to produce a profound impairment of long-term episodic memory, while at the same time sparing working memory. However, this neuropsychological dissociation has rarely been examined in detail. While a few studies have assessed some components of working memory in TGA, the results that have been obtained are far from conclusive. To clarify this issue, we carried out a comprehensive investigation of working memory in 10 patients during a TGA attack. In the first study, we report the results from three patients examined with a battery of neuropsychological tests designed to assess each of the three subcomponents of Baddeley's model of working memory. In a second study, seven different patients underwent neuropsychological investigations that focused specifically on the central executive system, using a protocol derived from a study by Miyake and colleagues. Our findings showed that subcomponents of working memory, such as the phonological loop and visuo-spatial sketch pad, were spared in TGA patients. Specific executive functions that entailed inhibitory control, dual task performance, updating and shifting mechanisms were also found to be normal. However, we found significantly impaired performance for the Brown-Peterson test, and that TGA patients were significantly impaired in the recollection of their episodic memories. They also made reduced numbers of 'remember' compared with 'know' judgments in the episodic memory test several days after TGA. On the basis of our findings, it would appear that the episodic memory deficit during TGA is not related to elementary aspects of executive functioning. Our data also highlight the nature of the cognitive mechanisms involved in the Brown-Peterson task, which may well depend on long-term memory (such as the process of semantic encoding). Lastly, the selective deficit in recollective episodic memories observed in TGA may be principally related to medial temporal lobe abnormalities that have been reported in this syndrome.

Semantic acquisition without memories: evidence from transient global amnesia.

PubMed

Guillery, B; Desgranges, B; Katis, S; de la Sayette, V; Viader, F; Eustache, F

2001-12-04

Transient global amnesia (TGA), characterised by a profound anterograde amnesia, is a model of interest to study the acquisition of novel meanings independent of episodic functioning. Three patients were tested during a TGA attack, two in the early recovery phase and the third during the acute phase of TGA, with a semantic priming task involving a restructuring process of conceptual knowledge. During TGA, all patients demonstrated priming effects. Results obtained the day after the episode with the same task showed that these effects persisted at least one day. Episodic memory seems not to be critical for the formation of novel connections among unrelated semantic representations, in accordance with Tulving's model of memory, i.e. episodic memory is not necessary for the acquisition of semantic information.

Enzymatic degradation of thiolated chitosan.

PubMed

Laffleur, Flavia; Hintzen, Fabian; Rahmat, Deni; Shahnaz, Gul; Millotti, Gioconda; Bernkop-Schnürch, Andreas

2013-10-01

The objective of this study was to evaluate the biodegradability of thiolated chitosans in comparison to unmodified chitosan. Mediated by carbodiimide, thioglycolic acid (TGA) and mercaptonicotinic acid (MNA) were covalently attached to chitosan via formation an amide bond. Applying two different concentrations of carbodiimide 50 and 100 mM, two chitosan TGA conjugates (TGA A and TGA B) were obtained. According to chitosan solution (3% m/v) thiomer solutions were prepared and chitosanolytic enzyme solutions were added. Lysozyme, pectinase and cellulase were examined in chitosan degrading activity. The enzymatic degradability of these thiomers was investigated by viscosity measurements with a plate-plate viscometer. The obtained chitosan TGA conjugate A displayed 267.7 µmol and conjugate B displayed 116.3 µmol of immobilized thiol groups. With 325.4 µmol immobilized thiol groups, chitosan MNA conjugate displayed the most content of thiol groups. In rheological studies subsequently the modification proved that chitosan TGA conjugates with a higher coupling rate of thiol groups were not only degraded to a lesser extent by 20.9-26.4% but also more slowly. Chitosan mercaptonicotinic acid was degraded by 31.4-50.1% depending the investigated enzyme and even faster than unmodified chitosan. According to these results the biodegradability can be influenced by various modifications of the polymer which showed in particular that the rate of biodegradation is increased when MNA is the ligand, whereas the degradation is hampered when TGA is used as ligand for chitosan.

Correlation to FVIII:C in Two Thrombin Generation Tests: TGA-CAT and INNOVANCE ETP.

PubMed

Ljungkvist, Marcus; Berndtsson, Maria; Holmström, Margareta; Mikovic, Danijela; Elezovic, Ivo; Antovic, Jovan P; Zetterberg, Eva; Berntorp, Erik

2017-01-01

Several thrombin-generation tests are available, but few have been directly compared. Our primary aim was to investigate the correlation of two thrombin generation tests, thrombin generation assay-calibrated automated thrombogram (TGA-CAT) and INNOVANCE ETP, to factor VIII levels (FVIII:C) in a group of patients with hemophilia A. The secondary aim was to investigate inter-laboratory variation for the TGA-CAT method. Blood samples were taken from 45 patients with mild, moderate and severe hemophilia A. The TGA-CAT method was performed at both centers while the INNOVANCE ETP was only performed at the Stockholm center. Correlation between parameters was evaluated using Spearman's rank correlation test. For determination of the TGA-CAT inter-laboratory variability, Bland-Altman plots were used. The correlation for the INNOVANCE ETP and TGA-CAT methods with FVIII:C in persons with hemophilia (PWH) was r=0.701 and r=0.734 respectively.The correlation between the two methods was r=0.546.When dividing the study material into disease severity groups (mild, moderate and severe) based on FVIII levels, both methods fail to discriminate between them.The variability of the TGA-CAT results performed at the two centers was reduced after normalization; before normalization, 29% of values showed less than ±10% difference while after normalization the number increased to 41%. Both methods correlate in an equal manner to FVIII:C in PWH but show a poor correlation with each other. The level of agreement for the TGA-CAT method was poor though slightly improved after normalization of data. Further improvement of standardization of these methods is warranted.

Enhanced Thermal Properties of Novel Latent Heat Thermal Storage Material Through Confinement of Stearic Acid in Meso-Structured Onion-Like Silica

NASA Astrophysics Data System (ADS)

Gao, Junkai; Lv, Mengjiao; Lu, Jinshu; Chen, Yan; Zhang, Zijun; Zhang, Xiongjie; Zhu, Yingying

2017-12-01

Meso-structured onion-like silica (MOS), which had a highly ordered, onion-like multilayer; large surface area and pore volume; and highly curved mesopores, were synthesized as a support for stearic acid (SA) to develop a novel shape-stabilized phase change material (SA/MOS). The characterizations of SA/MOS were studied by the analysis technique of scanning electron microscope, infrared spectroscopy, x-ray diffraction, differential scanning calorimeter (DSC), and thermal gravimetry analysis (TGA). The results showed that the interaction between the SA and the MOS was physical adsorption and that the MOS had no effect on the crystal structure of the SA. The DSC results suggested that the melting and solidifying temperature of the SA/MOS were 72.7°C and 63.9°C with a melting latent heat of 108.0 J/g and a solidifying latent heat of 126.0 J/g, respectively, and the TGA results indicated that the SA/MOS had a good thermal stability. All of the results demonstrated that the SA/MOS was a promising thermal energy storage material candidate for practical applications.

Hydrogen and oxygen stable isotope signatures of goethite hydration waters by thermogravimetry-enabled laser spectroscopy

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

Oerter, Erik; Singleton, Michael; Davisson, Lee

The hydrogen and oxygen stable isotope composition (δ 2H and δ 18O values) of mineral hydration waters can give information on the environment of mineral formation. Here we present and validate an approach for the stable isotope analysis of mineral hydration waters based on coupling a thermogravimetric analyzer with a laser-based isotope ratio infrared spectroscopy instrument (Picarro L-2130i), which we abbreviate as TGA-IRIS. TGA-IRIS generates δ 2H and δ 18O values of liquid water samples with precision for δ 2H of ± 1.2‰, and for δ 18O of ± 0.17‰. For hydration waters in goethite, precision for δ 2H rangesmore » from ± 0.3‰ to 1.6‰, and for δ 18O ranges from ± 0.17‰ to 0.27‰. The ability of TGA-IRIS to generate detailed water yield data and δ 2H and δ 18O values of water at varying temperatures allows for the differentiation of water in varying states of binding on mineral surfaces and within the mineral matrix. TGA-IRIS analyses of hydrogen isotopes in goethite yields δ 2H values that reflect the hydrogen of the OH – phase in the mineral and are comparable to that made by IRMS and found in the literature. In contrast, δ 18O values on goethite reflect the oxygen in OH – groups bound to Fe (Fe-OH group), and not the oxygen bound only to Fe (Fe-O group) in the mineral crystal lattice, and may not be comparable to literature δ 18O values made by IRMS that reflect the total O in the mineral. TGA-IRIS presents the possibility to isotopically differentiate the various oxygen reservoirs in goethite, which may allow the mineral to be used as a single mineral geothermometer. As a result, TGA-IRIS measurements of hydration waters are likely to open new avenues and possibilities for research on hydrated minerals.« less

Hydrogen and oxygen stable isotope signatures of goethite hydration waters by thermogravimetry-enabled laser spectroscopy

DOE PAGES

Oerter, Erik; Singleton, Michael; Davisson, Lee

2017-10-22

The hydrogen and oxygen stable isotope composition (δ 2H and δ 18O values) of mineral hydration waters can give information on the environment of mineral formation. Here we present and validate an approach for the stable isotope analysis of mineral hydration waters based on coupling a thermogravimetric analyzer with a laser-based isotope ratio infrared spectroscopy instrument (Picarro L-2130i), which we abbreviate as TGA-IRIS. TGA-IRIS generates δ 2H and δ 18O values of liquid water samples with precision for δ 2H of ± 1.2‰, and for δ 18O of ± 0.17‰. For hydration waters in goethite, precision for δ 2H rangesmore » from ± 0.3‰ to 1.6‰, and for δ 18O ranges from ± 0.17‰ to 0.27‰. The ability of TGA-IRIS to generate detailed water yield data and δ 2H and δ 18O values of water at varying temperatures allows for the differentiation of water in varying states of binding on mineral surfaces and within the mineral matrix. TGA-IRIS analyses of hydrogen isotopes in goethite yields δ 2H values that reflect the hydrogen of the OH – phase in the mineral and are comparable to that made by IRMS and found in the literature. In contrast, δ 18O values on goethite reflect the oxygen in OH – groups bound to Fe (Fe-OH group), and not the oxygen bound only to Fe (Fe-O group) in the mineral crystal lattice, and may not be comparable to literature δ 18O values made by IRMS that reflect the total O in the mineral. TGA-IRIS presents the possibility to isotopically differentiate the various oxygen reservoirs in goethite, which may allow the mineral to be used as a single mineral geothermometer. As a result, TGA-IRIS measurements of hydration waters are likely to open new avenues and possibilities for research on hydrated minerals.« less

Electrospinning of PVC with natural rubber

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

Othman, Muhammad Hariz; Abdullah, Ibrahim; Mohamed, Mahathir

Polyvinyl chloride (PVC) was mixed with natural rubbers which are liquid natural rubber (LNR), liquid epoxidised natural rubber (LENR) and liquid epoxidised natural rubber acrylate (LENRA) for a preparation of a fine non-woven fiber’s mat. PVC and each natural rubbers(PVC:LENR, PVC:LNR and PVC:LENRA) were mixed based on ratio of 70:30. Electrospinning method was used to prepare the fiber. The results show that the spinnable concentration of PVC/ natural rubber/THF solution is 16 wt%. The morphology, diameter, structure and degradation temperature of electrospun fibers were investigated by scanning electron microscopy (SEM) and thermogravimetric analysis (TGA). SEM photos showed that the morphologymore » and diameter of the fibers were mainly affected by the addition of natural rubber. TGA results suggested that PVC electrospun fiber has higher degradation temperature than those electrospun fibers that contain natural rubber.« less

Synthesis of polymer hybrid latex poly(methyl methacrylate-co-butyl acrylate) with organo montmorillonite via miniemulsion polymerization method for barrier paper

NASA Astrophysics Data System (ADS)

Chanra, J.; Budianto, E.; Soegijono, B.

2018-03-01

Hybrid polymer latex based on combination of organic-inorganic materials, poly(methyl methacrylate-co-butyl acrylate) (PMMBA) and organo-montmorillonite (OMMT) were synthesized via miniemulsion polymerization technique. Modification of montmorillonite (MMT) through the incorporation of myristyltrimethylammonium bromide (MTAB) into the clay’s interlayer spaces were investigated by Small-Angle X-ray Scattering (SAXS), Fourier Transform Infrared Spectroscopy (FTIR), Thermogravimetric Analysis (TGA) and Transmission Electron Microscopy (TEM). Barrier property and thermal stability of polymer latex film sample were investigated through its Water Vapor Transmission Rate (WVTR) and Thermogravimetric Analysis (TGA). The results indicated that addition of OMMT as filler in PMMBA increased the barrier property and thermal stability of the latex film. Addition of 8.0% (wt) OMMT increased the barrier property and thermal stability. Miniemusion polymerization process with higher addition (>8.0 wt%) of OMMT resulting in high latex viscosity, particle size, and high amount of coagulum. The utilization of this hybrid polymer could benefits paper and board industries to produce high quality barrier paper for food packaging.

Biomass pyrolysis and combustion integral and differential reaction heats with temperatures using thermogravimetric analysis/differential scanning calorimetry.

PubMed

Shen, Jiacheng; Igathinathane, C; Yu, Manlu; Pothula, Anand Kumar

2015-06-01

Integral reaction heats of switchgrass, big bluestem, and corn stalks were determined using thermogravimetric analysis/differential scanning calorimetry (TGA/DSC). Iso-conversion differential reaction heats using TGA/DSC pyrolysis and combustion of biomass were not available, despite reports available on heats required and released. A concept of iso-conversion differential reaction heats was used to determine the differential reaction heats of each thermal characteristics segment of these materials. Results showed that the integral reaction heats were endothermic from 30 to 700°C for pyrolysis of switchgrass and big bluestem, but they were exothermic for corn stalks prior to 587°C. However, the integral reaction heats for combustion of the materials followed an endothermic to exothermic transition. The differential reaction heats of switchgrass pyrolysis were predominantly endothermic in the fraction of mass loss (0.0536-0.975), and were exothermic for corn stalks (0.0885-0.850) and big bluestem (0.736-0.919). Study results provided better insight into biomass thermal mechanism. Published by Elsevier Ltd.

Optical, thermal and morphological study of ZnS doped PVA polymer nano composites

NASA Astrophysics Data System (ADS)

Guruswamy, B.; Ravindrachary, V.; Shruthi, C.; Sagar, Rohan N.; Hegde, Shreedatta

2018-05-01

The effect of ZnS nano particle doping on optical, thermal properties and morphological study of the PVA polymer has been investigated using FTIR, UV-Visible and TGA, FESEM techniques. Nano sized ZnS particles were synthesized by a simple wet chemical route. Pure and ZnS/PVA nano composites were prepared using solution casting technique. The FTIR study confirms that the ZnS nano particles interacts with the OH group of PVA polymer and forms the complex. The formation of these complexes affects the optical and thermal properties of the composite. The changes in optical properties were studied using UV-Vis absorption method. The variation in thermal property was analysed using TGA results. The modified surface morphology analysis was carried out using FESEM.

Peripheral Endothelial Function After Arterial Switch Operation for D-looped Transposition of the Great Arteries.

PubMed

Sun, Heather Y; Stauffer, Katie Jo; Nourse, Susan E; Vu, Chau; Selamet Tierney, Elif Seda

2017-06-01

Coronary artery re-implantation during arterial switch operation in patients with D-looped transposition of the great arteries (D-TGA) can alter coronary arterial flow and increase shear stress, leading to local endothelial dysfunction, although prior studies have conflicting results. Endothelial pulse amplitude testing can predict coronary endothelial dysfunction by peripheral arterial testing. This study tested if, compared to healthy controls, patients with D-TGA after arterial switch operation had peripheral endothelial dysfunction. Patient inclusion criteria were (1) D-TGA after neonatal arterial switch operation; (2) age 9-29 years; (3) absence of known cardiovascular risk factors such as hypertension, diabetes, hypercholesterolemia, vascular disease, recurrent vasovagal syncope, and coronary artery disease; and (4) ability to comply with overnight fasting. Exclusion criteria included (1) body mass index ≥85th percentile, (2) use of medications affecting vascular tone, or (3) acute illness. We assessed endothelial function by endothelial pulse amplitude testing and compared the results to our previously published data in healthy controls (n = 57). We tested 20 D-TGA patients (16.4 ± 4.8 years old) who have undergone arterial switch operation at a median age of 5 days (0-61 days). Endothelial pulse amplitude testing indices were similar between patients with D-TGA and controls (1.78 ± 0.61 vs. 1.73 ± 0.54, p = 0.73).In our study population of children and young adults, there was no evidence of peripheral endothelial dysfunction in patients with D-TGA who have undergone arterial switch operation. Our results support the theory that coronary arterial wall thickening and abnormal vasodilation reported in these patients is a localized phenomenon and not reflective of overall atherosclerotic burden.

Hydrothermal synthesis and characterization of a novel supramolecular network compound of Co(NIA) 2(H 2O) 4 with molecular ladder hydrogen bond chains (NIA=nicotinate)

NASA Astrophysics Data System (ADS)

Jia, Hong-Bin; Yu, Jie-Hui; Xu, Ji-Qing; Ye, Ling; Ding, Hong; Jing, Wei-Jie; Wang, Tie-Gang; Xu, Jia-Ning; Li, Zeng-Chun

2002-10-01

By hydrothermal method, a novel supramolecular compound, Co(NIA) 2(H 2O) 4 was synthesized and its structure was characterized with elemental analysis, FT-IR spectrum, TGA and X-ray diffractometer, indicating that it is a novel polyporous supramolecule with molecular ladder hydrogen-bonded chains. TGA curve shows its thermal stability up to 520 °C.

Isothermal thermogravimetric data acquisition analysis system

NASA Technical Reports Server (NTRS)

Cooper, Kenneth, Jr.

1991-01-01

The description of an Isothermal Thermogravimetric Analysis (TGA) Data Acquisition System is presented. The system consists of software and hardware to perform a wide variety of TGA experiments. The software is written in ANSI C using Borland's Turbo C++. The hardware consists of a 486/25 MHz machine with a Capital Equipment Corp. IEEE488 interface card. The interface is to a Hewlett Packard 3497A data acquisition system using two analog input cards and a digital actuator card. The system provides for 16 TGA rigs with weight and temperature measurements from each rig. Data collection is conducted in three phases. Acquisition is done at a rapid rate during initial startup, at a slower rate during extended data collection periods, and finally at a fast rate during shutdown. Parameters controlling the rate and duration of each phase are user programmable. Furnace control (raising and lowering) is also programmable. Provision is made for automatic restart in the event of power failure or other abnormal terminations. Initial trial runs were conducted to show system stability.

Some critical aspects of FT-IR, TGA, powder XRD, EDAX and SEM studies of calcium oxalate urinary calculi.

PubMed

Joshi, Vimal S; Vasant, Sonal R; Bhatt, J G; Joshi, Mihir J

2014-06-01

Urinary calculi constitute one of the oldest afflictions of humans as well as animals, which are occurring globally. The calculi vary in shape, size and composition, which influence their clinical course. They are usually of the mixed-type with varying percentages of the ingredients. In medical management of urinary calculi, either the nature of calculi is to be known or the exact composition of calculi is required. In the present study, two selected calculi were recovered after surgery from two different patients for detailed examination and investigated by using Fourier-Transform infrared spectroscopy (FT-IR), thermo-gravimetric analysis (TGA), powder X-ray diffraction (XRD), scanning electron microscopy and energy dispersive analysis of X-rays (EDAX) techniques. The study demonstrated that the nature of urinary calculi and presence of major phase in mixed calculi could be identified by FT-IR, TGA and powder XRD, however, the exact content of various elements could be found by EDAX only.

Pyrolysis characteristics and kinetics of microalgae via thermogravimetric analysis (TGA): A state-of-the-art review.

PubMed

Bach, Quang-Vu; Chen, Wei-Hsin

2017-12-01

Pyrolysis is a promising route for biofuels production from microalgae at moderate temperatures (400-600°C) in an inert atmosphere. Depending on the operating conditions, pyrolysis can produce biochar and/or bio-oil. In practice, knowledge for thermal decomposition characteristics and kinetics of microalgae during pyrolysis is essential for pyrolyzer design and pyrolysis optimization. Recently, the pyrolysis kinetics of microalgae has become a crucial topic and received increasing interest from researchers. Thermogravimetric analysis (TGA) has been employed as a proven technique for studying microalgae pyrolysis in a kinetic control regime. In addition, a number of kinetic models have been applied to process the TGA data for kinetic evaluation and parameters estimation. This paper aims to provide a state-of-the art review on recent research activities in pyrolysis characteristics and kinetics of various microalgae. Common kinetic models predicting the thermal degradation of microalgae are examined and their pros and cons are illustrated. Copyright © 2017 Elsevier Ltd. All rights reserved.

Synthesis, characterization and dissolution of three pharmaceutical cocrystals based on deferiprone

NASA Astrophysics Data System (ADS)

Zhang, Xiaoming; Tian, Yuyang; Jia, Jiangtao; Zhang, Tingting; Zhu, Guangshan

2016-03-01

In this paper we present three new cocrystals based on deferiprone which is the first oral medicine as iron chelator. Solitary deferiprone possesses some known problems due to its good solubility and frequent dosing side effects. For these three novel co crystals, deferiprone is the active pharmaceutical ingredient (API), p-hydroxybenzoic acid (1, C7H9NO2·C7H6O3), 2, 5-dihydroxybenzoic acid (2, C7H9NO2·C7H6O4) and maleic acid (3, C7H9NO2·C4H4O4) are used as cocrystal formers (CCFs), respectively. Their structures were characterized by single crystal X-ray diffraction, powder X-ray diffraction (PXRD) analysis, thermogravimetric analyses (TGA), differential thermal analysis (DTA), elemental analysis (EA) and infrared spectral analysis (IR). Single crystal X-ray diffraction demonstrates that all three cocrystals (1-3) possess strong hydrogen-bondings assembled through hydroxyl of API and carboxylic acids of CCFs. The PXRD results indicate their high purity of as-synthesized samples. TGA, DTA, EA, IR and dissolution study of API and cocrystals were also measured and discussed, respectively. The results suggest that the cocrystals exhibit low dissolution rates comparing with solitary deferiprone, which is very advantageous for the oral medicine with frequent dosing side effects.

Evaluating the combustion reactivity of drop tube furnace and thermogravimetric analysis coal chars with a selection of metal additives

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

Katherine Le Manquais; Colin E. Snape; Ian McRobbie

Opportunities exist for effective coal combustion additives that can reduce the carbon content of pulverized fuel ash (PFA) to below 6%, thereby making it saleable for filler/building material applications without the need for postcombustion treatment. However, with only limited combustion data currently available for the multitude of potential additives, catalytic performance under pulverized fuel (PF) boiler conditions has received relatively little attention. This paper therefore compares the reactivity of catalyzed bituminous coal chars from thermogravimetric analysis (TGA) with those generated by devolatilization in a drop tube furnace (DTF). The principal aim was to explore the fundamental chemistry behind the chosenmore » additives' relative reactivities. Accordingly, all eight of the investigated additives increased the TGA burnout rate of the TGA and DTF chars, with most of the catalysts demonstrating consistent reactivity levels across chars from both devolatilization methods. Copper(I) chloride, silver chloride, and copper nitrate were thus identified as the most successful additives tested, but it proved difficult to establish a definitive reactivity ranking. This was largely due to the use of physical mixtures for catalyst dispersion, the relatively narrow selection of additives examined, and the inherent variability of the DTF chars. Nevertheless, one crucial exception to normal additive behavior was discovered, with copper(I) chloride perceptibly deactivating during devolatilization in the DTF, even though it remained the most effective catalyst tested. As a prolonged burnout at over 1000{sup o}C was required to replicate this deactivation effect on the TGA, the phenomenon could not be detected by typical testing procedures. Subsequently, a comprehensive TGA study showed no obvious relationship between the catalyst-induced reductions in the reaction's apparent activation energy and the samples recorded burnout rates.« less

Physicochemical characterization of chitosan/nylon6/polyurethane foam chemically cross-linked ternary blends.

PubMed

Jayakumar, S; Sudha, P N

2013-03-15

Chitosan/nylon6/polyurethane foam (CS/Ny6/PUF) ternary blend was prepared and chemically cross-linked with glutaraldehyde. Structural, thermal and morphological studies were performed for the prepared ternary blends. Characterizations of the ternary blends were investigated by Fourier transform infrared spectroscopy (FTIR), thermo gravimetric analysis (TGA), differential scanning calorimetry (DSC), X-ray diffraction (XRD) and scanning electron microscope (SEM). The FTIR results showed that the strong intermolecular hydrogen bonds took place between CS, Ny6 and PUF. TGA and DSC studies reveal that the thermal stability of the blend is enhanced by glutaraldehyde as crosslinking agent. Results of XRD indicated that the relative crystalline of pure CS film was reduced when the polymeric network was reticulated by glutaraldehyde. Finally, the results of scanning electron microscopy (SEM) indicated that the morphology of the blend is rough and heterogeneous, further it confirms the interaction between the functional groups of the blend components. Copyright © 2012 Elsevier B.V. All rights reserved.

Anemia and hematinic deficiencies in gastric parietal cell antibody-positive and antibody-negative erosive oral lichen planus patients with thyroid antibody positivity.

PubMed

Chang, Julia Y-F; Chen, I-Chang; Wang, Yi-Ping; Wu, Yu-Hsueh; Chen, Hsin-Ming; Sun, Andy

2016-11-01

Serum gastric parietal cell antibody (GPCA), thyroglobulin antibody (TGA), and thyroid microsomal antibody (TMA) are found in some erosive oral lichen planus (EOLP) patients. This study assessed whether serum GPCA, TGA and TMA and EOLP itself played significant roles in causing anemia and hematinic deficiencies in TGA/TMA-positive EOLP patients with GPCA positivity (GPCA + /TGA/TMA/EOLP patients) or negativity (GPCA - /TGA/TMA/EOLP patients). The mean corpuscular volume (MCV) and mean blood hemoglobin (Hb), iron, vitamin B12, and folic acid levels were measured and compared between any two of the four groups of 29 GPCA + /TGA/TMA/EOLP patients, 80 GPCA - /TGA/TMA/EOLP patients, 198 all antibodies-negative EOLP patients (Abs - /EOLP patients), and 218 healthy control individuals. GPCA + /TGA/TMA/EOLP patients had significantly lower mean Hb and vitamin B12 levels as well as significantly greater frequencies of Hb, iron, and vitamin B12 deficiencies than healthy controls. GPCA + /TGA/TMA/EOLP patients had significantly lower serum vitamin B12 level and higher MCV as well as a significantly greater frequency of vitamin B12 deficiency than GPCA - /TGA/TMA/EOLP patients. Furthermore, both GPCA - /TGA/TMA/EOLP and Abs - /EOLP patients did have significantly lower mean Hb, MCV, and iron (for women only) levels, as well as significantly greater frequencies of Hb and iron deficiencies than healthy controls. However, there were no significant differences in measured blood data between GPCA - /TGA/TMA/EOLP and Abs - /EOLP patients. We conclude that serum GPCA is the major factor causing vitamin B12 deficiency, macrocytosis and pernicious anemia in GPCA + /TGA/TMA/EOLP patients. ELOP itself but not TGA/TMA positivity plays a significant role in causing anemia and hematinic deficiencies in GPCA - /TGA/TMA/EOLP patients. Copyright © 2016. Published by Elsevier B.V.

Preparation and structural characterization of zwitterionic surfactant intercalated into NiZn-layered hydroxide salts

NASA Astrophysics Data System (ADS)

Liu, Jiexiang; Wang, Jianlong; Zhang, Xiaoguang; Fang, Binbin; Hu, Pan; Zhao, Xuyang

2015-10-01

Three zwitterionic surfactants, dodecyl dimethyl carboxylbetaine (DCB), dodecyl dimethyl sulfobetaine (DSB) and N-dodecyl-β-aminoprpionate (DAP), intercalated into NiZn-layered hydroxide salts (NZL-DCB, NZL-DSB and NZL-DAP) were synthesized by the coprecipitation method. The effect of surfactant content, pH, temperature and time of hydrothermal treatment on preparation was investigated and discussed. The NZL-DCB, NZL-DSB and NZL-DAP were characterized by powder X-ray diffraction (PXRD), Fourier transform infrared spectroscopy (FTIR), and thermogravimetry analysis and differential thermal analysis (TGA/DTA). The results showed that basal spacings of NZL-DCB, NZL-DSB and NZL-DAP were around 3.45, 3.68 and 3.94 nm, respectively. DCB, DSB and DAP probably form an overlapped bilayer in the gallery. TGA/DTA data indicated that NZL-DCB, NZL-DSB and NZL-DAP displayed three loss weight stages: loss of adsorbed and structural water, dehydroxylation of matrix and decomposition of nitrate ions, decomposition and combustion of surfactants. Furthermore, chemical analysis data, BET surface area and scanning electron microscopic (SEM) were also measured and analyzed.

Reusable and Mediator-Free Cholesterol Biosensor Based on Cholesterol Oxidase Immobilized onto TGA-SAM Modified Smart Bio-Chips

PubMed Central

Rahman, Mohammed M.

2014-01-01

A reusable and mediator-free cholesterol biosensor based on cholesterol oxidase (ChOx) was fabricated based on self-assembled monolayer (SAM) of thioglycolic acid (TGA) (covalent enzyme immobilization by dropping method) using bio-chips. Cholesterol was detected with modified bio-chip (Gold/Thioglycolic-acid/Cholesterol-oxidase i.e., Au/TGA/ChOx) by reliable cyclic voltammetric (CV) technique at room conditions. The Au/TGA/ChOx modified bio-chip sensor demonstrates good linearity (1.0 nM to 1.0 mM; R = 0.9935), low-detection limit (∼0.42 nM, SNR∼3), and higher sensitivity (∼74.3 µAµM−1cm−2), lowest-small sample volume (50.0 μL), good stability, and reproducibility. To the best of our knowledge, this is the first statement with a very high sensitivity, low-detection limit, and low-sample volumes are required for cholesterol biosensor using Au/TGA/ChOx-chips assembly. The result of this facile approach was investigated for the biomedical applications for real samples at room conditions with significant assembly (Au/TGA/ChOx) towards the development of selected cholesterol biosensors, which can offer analytical access to a large group of enzymes for wide range of biomedical applications in health-care fields. PMID:24949733

Instrumentation for studying binder burnout in an immobilized plutonium ceramic wasteform

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

Mitchell, M; Pugh, D; Herman, C

The Plutonium Immobilization Program produces a ceramic wasteform that utilizes organic binders. Several techniques and instruments were developed to study binder burnout on full size ceramic samples in a production environment. This approach provides a method for developing process parameters on production scale to optimize throughput, product quality, offgas behavior, and plant emissions. These instruments allow for offgas analysis, large-scale TGA, product quality observation, and thermal modeling. Using these tools, results from lab-scale techniques such as laser dilametry studies and traditional TGA/DTA analysis can be integrated. Often, the sintering step of a ceramification process is the limiting process step thatmore » controls the production throughput. Therefore, optimization of sintering behavior is important for overall process success. Furthermore, the capabilities of this instrumentation allows better understanding of plant emissions of key gases: volatile organic compounds (VOCs), volatile inorganics including some halide compounds, NO{sub x}, SO{sub x}, carbon dioxide, and carbon monoxide.« less

Polyvinyl Alcohol Microspheres Reinforced Thermoplastic Starch Composites

PubMed Central

Zha, Dongdong; Li, Bengang; Yin, Peng; Li, Panxin

2018-01-01

We reported a new method to prepare polyvinyl alcohol (PVA)/thermoplastic starch (TPS) composites by using polyvinyl alcohol microspheres (PVAMS). The PVAMS/TPS composites were characterized using tensile test, scanning electron microscopy (SEM), dynamic mechanical thermal analysis (DMTA) and thermogravimetric analysis (TGA). The results exhibited that adding small amounts of PVAMSs can effectively improve the mechanical strength and toughness of the composites, especially for the 1 wt %PVAMS in TPS matrix, with a tensile strength of 3.5 MPa, an elongation at break at 71.73% and an impact strength of 33.4 kJ/m2. Furthermore, the SEM and shift in the tan δ peak (Tα and Tβ) at the maximum value of 69.87 and −36.52 °C indicates that the PVAMS decreased the mobility of the amorphous starch molecules due to the strong intermolecular hydrogen bonds between PVAMS and TPS. The peak temperature of maximum decomposition rate (Tp) of 1 wt % PVAMS/TPS composites increased about 5 °C compared with TPS in TGA curves. PMID:29690506

Combustion and kinetic parameters estimation of torrefied pine, acacia and Miscanthus giganteus using experimental and modelling techniques.

PubMed

Wilk, Małgorzata; Magdziarz, Aneta; Gajek, Marcin; Zajemska, Monika; Jayaraman, Kandasamy; Gokalp, Iskender

2017-11-01

A novel approach, linking both experiments and modelling, was applied to obtain a better understanding of combustion characteristics of torrefied biomass. Therefore, Pine, Acacia and Miscanthus giganteus have been investigated under 260°C, 1h residence time and argon atmosphere. A higher heating value and carbon content corresponding to a higher fixed carbon, lower volatile matter, moisture content, and ratio O/C were obtained for all torrefied biomass. TGA analysis was used in order to proceed with the kinetics study and Chemkin calculations. The kinetics analysis demonstrated that the torrefaction process led to a decrease in Ea compared to raw biomass. The average Ea of pine using the KAS method changed from 169.42 to 122.88kJ/mol. The changes in gaseous products of combustion were calculated by Chemkin, which corresponded with the TGA results. The general conclusion based on these investigations is that torrefaction improves the physical and chemical properties of biomass. Copyright © 2017 Elsevier Ltd. All rights reserved.

Aluminum phosphate microcapsule flame retardants for flexible polyurethane foams

NASA Astrophysics Data System (ADS)

Zhang, Bin; Liu, Hong; Han, Jian

2018-04-01

In this study, highly efficient flame-retardant aluminum phosphate (ALP) microcapsules were synthesized from ALP and ammonium phosphomolybdate trihydrate. The chemical structure of the ALP microcapsules was characterized by scanning electron microscopy and elemental analysis, and the thermal degradation behavior was investigated by thermogravimetric analysis (TGA). Subsequently, flexible polyurethane (PU) foams were prepared with the ALP microcapsules. Limiting oxygen index (LOI) tests, vertical burning tests, smoke density rating (SDR), and cone calorimetric tests were employed to investigate the combustion of the materials. The results showed that the flexible PU foams with 15 parts per hundred polyol by weight (pphp) ALP microcapsules passed the vertical burning test and they had an increased LOI value of 28.5%. The SDR value for PU/20 pphp ALP microcapsule composites was about 16.0% and the SDR value for the pure PU was about 29.0%. The corresponding flame-retardant mechanism was investigated by Fourier transform infrared spectroscopy, TGA, Pyrolysis Gas Chromatography Mass Spectrometry (Py-GC/MS) tests, and energy-dispersive X-ray spectrometry.

Standardization of Shodhita Naga with special reference to thermogravimetry and infra-red spectroscopy.

PubMed

Rajput, Dhirajsingh S; Patgiri, Biswajyoti; Shukla, Vinay J

2014-01-01

Standardization of Ayurvedic medicine is the need of hour to obtain desired quality of final product. Shodhana literally means purification, is the initial step to make drugs like metals, minerals and poisonous herbs suitable for further procedure. Shodhana of metals/minerals help to expose maximum surface area of drug for chemical reactions and also in impregnation of organic materials and their properties in the drug. Thermo-gravimetric analysis (TGA) facilitates in identifying the presence of organic matter and change in the melting point of metal whereas Fourier transform infra-red spectroscopy (FTIR) assists in identifying the presence of various functional groups. To standardize the process of Naga Shodhana and to study the change in chemical nature of Shodhita Naga in each media through TGA and FTIR. Samanya and Vishesha Shodhana of Naga was carried out. Time taken for melting of Naga, physico-chemical changes in media used for Shodhana and weight changes after Shodhana were recorded. Samples of Naga were collected after Shodhana in each media for TGA and FTIR analysis. Average loss occurred during Shodhana was 6.26%. Melting point of Ashuddha Naga was 327.46°C, and it was 328.42°C after Shodhana. Percentage purity of Naga (percentage of lead in Naga) decreased after Shodhana from 99.80% to 99.40%. FTIR analysis of Shodhita Naga in each sample showed stretching vibrations particularly between C-H and C-N bonds that are indicating the presence of various organic compounds. According to TGA and FTIR analysis, Shodhana process increases melting point of Naga and initiation of new physico-chemical properties which are indicated by detection of large number of functional groups and organo-metallic nature of Shodhita Naga.

[A study of right-left shunt in transient global amnesia].

PubMed

de Francisco, J; Pujadas, F; Toledo, M; Santamarina, E; Quintana, M; Edo, M C; Centeno, M; Alvarez Sabín, J

2010-03-01

Transient global amnesia (TGA) is a disorder of unknown aetiology. In recent studies, TGA was associated with a right to left shunt (RLS). We studied the presence of the RLS in patients with TGA and we compared this series with patients who had suffered a transient ischaemic attack (TIA). We included 66 consecutive TGA patients. In these patients a transcranial Doppler was performed to determine the presence of a RLS. We collected data on the TGA episode, vascular risk factors, migraine history, recurrence of TGA and neuroimaging in patients with and without RLS. We compared the prevalence of the RLS in TGA series with 59 patients with TIA. The prevalence of RLS was 21.2% in patients with TGA. The RLS was associated with the migraine history (40% versus 13%; p = 0.014) and a Valsalva manoeuvre as a triggering factor (50% versus 14.5%; p = 0.022). A greater prevalence of RLS was detected in patients with TIA (55.9% versus 21.2%; p < 0.001). The RLS prevalence in TGA patients is similar to the general population but significantly lower than the prevalence in TIA patients. The association with a Valsalva manoeuvre as a precipitating factor in the TGA patients with RLS could play a role in the aetiopathogenesis of the TGA.

Cognitive findings after transient global amnesia: role of prefrontal cortex.

PubMed

Le Pira, Francesco; Giuffrida, Salvatore; Maci, Tiziana; Reggio, Ester; Zappalà, Giuseppe; Perciavalle, Vincenzo

2005-01-01

The aim of this study is to verify, after recovery, the presence of specific patterns of cognitive dysfunctions in Transient Global Amnesia (TGA). Fourteen patients with the diagnosis of TGA were submitted to a battery of neuropsychological tests and compared to a matched control group. We found significant qualitative and quantitative differences between TGA patients and controls in the California Verbal Learning Test (CLVT) and Rey-Osterrieth Complex Figure Test. Our data support the presence of selective cognitive dysfunctions after the clinical recovery. Moreover, for Verbal Fluency, Digit Span Backward, and Number of Clusters in the CVLT short-term memory test, the relation resulted as positively related with the temporal interval from the TGA episode. Reduction of categorical learning, attention, and qualitative alterations of spatial strategy seem to postulate a planning defect due to a prefrontal impairment.

Right ventricular performance and mass by use of cine MRI late after atrial repair of transposition of the great arteries.

PubMed

Lorenz, C H; Walker, E S; Graham, T P; Powers, T A

1995-11-01

The long-term adaptation of the right ventricle after atrial repair of transposition of the great arteries (TGA) remains a subject of major concern. Cine magnetic resonance imaging (MRI), with its tomographic capabilities, allows unique quantitative evaluation of both right and left ventricular function and mass. Our purpose was to use MRI and an age-matched normal population to examine the typical late adaptation of the right and left ventricles after atrial repair of TGA. Cine MRI was used to study ventricular function and mass in 22 patients after atrial repair of TGA. Images were obtained in short-axis sections from base to apex to derive normalized right and left ventricular mass (RVM and LVM, g/m2), interventricular septal mass (IVSM, g/m2), RV and LV end-diastolic volumes (EDV, mL/m2), and ejection fractions (EF). Results 8 to 23 years after repair were compared with analysis of 24 age- and sex-matched normal volunteers and revealed markedly elevated RVM, decreased LVM and IVSM, normal RV size, and only mildly depressed RVEF. Only 1 of 22 patients had clinical RV dysfunction, and this patient had increased RVM. Cine MRI allows quantitative evaluation of both RV and LV mass and function late after atrial repair of TGA. Longitudinal studies that include these measurements should prove useful in determining the mechanism of late RV failure in these patients. On the basis of these early data, inadequate hypertrophy does not appear to be the cause of late dysfunction in this patient group.

Hydrogen measurement during steam oxidation using coupled thermogravimetric analysis and quadrupole mass spectrometry

DOE PAGES

Parkison, Adam J.; Nelson, Andrew Thomas

2016-01-11

An analytical technique is presented with the goal of measuring reaction kinetics during steam oxidation reactions for three cases in which obtaining kinetics information often requires a prohibitive amount of time and cost. The technique presented relies on coupling thermogravimetric analysis (TGA) with a quantitative hydrogen measurement technique using quadrupole mass spectrometry (QMS). The first case considered is in differentiating between the kinetics of steam oxidation reactions and those for simultaneously reacting gaseous impurities such as nitrogen or oxygen. The second case allows one to independently measure the kinetics of oxide and hydride formation for systems in which both ofmore » these reactions are known to take place during steam oxidation. The third case deals with measuring the kinetics of formation for competing volatile and non-volatile oxides during certain steam oxidation reactions. In order to meet the requirements of the coupled technique, a methodology is presented which attempts to provide quantitative measurement of hydrogen generation using QMS in the presence of an interfering fragmentation species, namely water vapor. This is achieved such that all calibrations and corrections are performed during the TGA baseline and steam oxidation programs, making system operation virtually identical to standard TGA. Benchmarking results showed a relative error in hydrogen measurement of 5.7–8.4% following the application of a correction factor. Lastly, suggestions are made for possible improvements to the presented technique so that it may be better applied to the three cases presented.« less

Hydrogen measurement during steam oxidation using coupled thermogravimetric analysis and quadrupole mass spectrometry

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

Parkison, Adam J.; Nelson, Andrew Thomas

An analytical technique is presented with the goal of measuring reaction kinetics during steam oxidation reactions for three cases in which obtaining kinetics information often requires a prohibitive amount of time and cost. The technique presented relies on coupling thermogravimetric analysis (TGA) with a quantitative hydrogen measurement technique using quadrupole mass spectrometry (QMS). The first case considered is in differentiating between the kinetics of steam oxidation reactions and those for simultaneously reacting gaseous impurities such as nitrogen or oxygen. The second case allows one to independently measure the kinetics of oxide and hydride formation for systems in which both ofmore » these reactions are known to take place during steam oxidation. The third case deals with measuring the kinetics of formation for competing volatile and non-volatile oxides during certain steam oxidation reactions. In order to meet the requirements of the coupled technique, a methodology is presented which attempts to provide quantitative measurement of hydrogen generation using QMS in the presence of an interfering fragmentation species, namely water vapor. This is achieved such that all calibrations and corrections are performed during the TGA baseline and steam oxidation programs, making system operation virtually identical to standard TGA. Benchmarking results showed a relative error in hydrogen measurement of 5.7–8.4% following the application of a correction factor. Lastly, suggestions are made for possible improvements to the presented technique so that it may be better applied to the three cases presented.« less

RuO2/Activated Carbon Composite Electrode Prepared by Modified Colloidal Procedure and Thermal Decomposition Method

NASA Astrophysics Data System (ADS)

Li, Xiang; Zheng, Feng; Gan, Weiping; Luo, Xun

2016-01-01

RuO2/activated carbon (AC) composite electrode was prepared by a modified colloidal procedure and a thermal decomposition method. The precursor for RuO2/AC was coated on tantalum sheet and annealed at 150°C to 190°C for 3 h to develop thin-film electrode. The microstructure and morphology of the RuO2/AC film were characterized by thermogravimetric analysis (TGA), x-ray diffraction (XRD) analysis, and scanning electron microscopy (SEM). The TGA results showed the maximum loss of RuO2/AC composite film at 410°C, with residual RuO2 of 23.17 wt.%. The amorphous phase structure of the composite was verified by XRD analysis. SEM analysis revealed that fine RuO2 particles were dispersed in an activated carbon matrix after annealing. The electrochemical properties of RuO2/AC electrode were examined by cycling voltammetry, galvanostatic charge-discharge, and cyclic behavior measurements. The specific capacitance of RuO2/AC electrode reached 245 F g-1. The cyclic behavior of RuO2/AC electrode was stable. Optimal annealing was achieved at 170°C for 3 h.

Interaction of TGA with CdSe nanoparticles

NASA Astrophysics Data System (ADS)

Bharti, Shivani; Singh, Satvinder; Jain, Shikshita; Kaur, Gurvir; Gupta, Shikha; Tripathi, S. K.

2018-05-01

In this paper, the interaction of thioglycolic acid (TGA) with CdSe atomic cluster have been studied using first principle calculations and experimentally synthesized using chemical route method. Density Functional Theory (DFT) have been used for all the calculations. Structural and electronic properties have been studied theorectically and results have been compared to the experimentally obtained micrographs from TEM microscopy. The most stable interaction of CdSe cluster is obtained with thiol group of TGA due to the high bond dissiciation energy between Cd-S than Cd-O. Theoretical calculations have been performed using Gaussian basis set approach.

Study on the conformation changes of Lysozyme induced by Hypocrellin A: The mechanism investigation

NASA Astrophysics Data System (ADS)

Ma, Fei; Huang, He-Yong; Zhou, Lin; Yang, Chao; Zhou, Jia-Hong; Liu, Zheng-Ming

2012-11-01

The interactions between Lysozyme and Hypocrellin A are investigated in details using time-resolved fluorescence, fourier transform infrared spectroscopy (FTIR), circular dichroism spectroscopy (CD), three-dimensional fluorescence spectra, and thermal gravimetric analysis (TGA) techniques. The results of time-resolved fluorescence suggest that the quenching mechanism is static quenching. FTIR and CD spectroscopy provide evidences of the reducing of α-helix after interaction. Hypocrellin A could change the micro-environmental of Lysozyme according to hydrophobic interaction between the aromatic ring and the hydrophobic amino acid residues, and the altered polypeptide backbone structures induce the reduction of α-helical structures. Moreover, TGA study further demonstrates the structure changes of Lysozyme on the effect of Hypocrellin A. This study could provide some important information for the derivatives of HA in pharmacy, pharmacology and biochemistry.

Is intestinal biopsy always needed for diagnosis of celiac disease?

PubMed

Scoglio, Riccardo; Di Pasquale, Giuseppe; Pagano, Giuseppe; Lucanto, Maria Cristina; Magazzù, Giuseppe; Sferlazzas, Concetta

2003-06-01

Intestinal biopsy is required for a diagnosis of celiac disease (CD). The aim of this study was to assess diagnostic accuracy of transglutaminase antibodies (TGA) in comparison and in association with that of antiemdomysial antibodies (AEA), calculating the post-test odds of having the disease, to verify whether some patients might avoid undergoing intestinal biopsy for a diagnosis of CD. A total of 181 consecutive patients (131 < 18 yr), referred to our celiac clinic by primary care physicians for suspect CD. Overall diagnostic accuracy, negative predictive value, and likelihood ratio (LR) were calculated both for each serological test and for serial testing (TGA and after AEA, assuming the post-test probability of TGA as pretest probability of AEA). Both serological determination and histological evaluation were blindly performed. Histology of duodenal mucosa was considered the gold standard. The overall accuracy of TGA and of AEA were 92.8% (89.1-96.6) and 93.4% (89.7-97.0), respectively. The negative predictive value of TGA and AEA were 97.2% (91.9-102.6) and 87.2% (77.7-96.8), respectively. Positive likelihood ratios for TGA and AEA were 3.89 (3.40-4.38) and 7.48 (6.73-8.23), respectively. Serial testing, in groups of patients with prevalence of CD estimated higher than 75%, such as those with classic symptoms of CD, would provide a post-test probability of more than 99%. Our results suggest that serial testing with TGA and AEA might allow, in some cases, the avoidance of intestinal biopsy to confirm the diagnosis of CD.

Thermal Analysis Study of Antihypertensive Drugs Telmisartan and Cilazapril

PubMed Central

Saber, Refaat Ahmed; Attia, Ali Kamal; Salem, Waheed Mohamed

2014-01-01

Purpose: The aim of the present work is to study the thermal analysis of telmisartan and cilazapril. Methods: Thermogravimetry (TGA), derivative thermogravimetry (DTG) and differential thermal analysis (DTA) were used through the work to achieve the thermal analysis study of some antihypertensive drugs, telmisartan and cilazapril. Results: The results led to thermal stability data and also to the interpretation concerning the thermal decomposition. Thermogravimetry data allowed determination of the kinetic parameters such as, activation energy and frequency factor. Conclusion: The simplicity, speed and low operational costs of thermal analysis justify its application in the quality control of pharmaceutical compounds for medications. PMID:24754013

Effects of orbital exposure on Halar during the LDEF mission

NASA Technical Reports Server (NTRS)

Brower, William E., Jr.; Holla, Harish; Bauer, Robert A.

1992-01-01

Thermomechanical Analysis (TMA), Differential Scanning Calorimetry (DSC), and Thermogravimetric Analysis (TGA) were performed on samples of Halar exposed on the LDEF Mission for 6 years in orbit and unexposed Halar control samples. Sections 10-100 microns thick were removed from the exposed surface down to a depth of 1,000 microns through the 3 mm thick samples. The TMA and DSC results, which arise from the entire slice and not just its surface, showed no differences between the LDEF and the control samples. TMA scans were run from ambient to 300 C; results were compared by a tabulation of the glass transition temperatures. DSC scans were run from ambient to 700 C; the enthalpy of melting was compared for the samples as a function of section depth with the sample. The TGA results, which arise from the surface of the sample initially, showed a sharp increase in the topmost 50 micron section (the exposed, discolored side) in the weight loss of 170 C in oxygen. This weight loss dropped to bulk values in the range of depth of 50-200 microns. The control sample showed only a slight increase in weight loss as the top surface was approached. The LDEF Halar sample appears to be mechanically undamaged, with a surface layer which oxidizes faster as a result of orbital exposure.

Co-assembly of Zn(SPh){sub 2} and organic linkers into helical and zig-zag polymer chains

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

Liu Yi; Yu Lingmin; Loo, Say Chye Joachim

2012-07-15

Two novel one-dimensional coordination polymers, single helicate [Zn(SPh){sub 2}(TPyTA)(EG)]{sub n} (EG=ethylene glycol) (1) and zig-zag structure [Zn(SPh){sub 2}(BPyVB)]{sub n} (2), were synthesized under solvothermal conditions at 150 Degree-Sign C or room temperature by the co-assembly of Zn(SPh){sub 2} and organic linkers such as 2,4,6-tri(4-pyridyl)-1,3,5-triazine (TPyTA) and 1,3-bis(trans-4-pyridylvinyl)benzene (BPyVB). X-ray crystallography study reveals that both polymers 1 and 2 crystallize in space group P2{sub 1}/c of the monoclinic system. The solid-state UV-vis absorption spectra show that 1 and 2 have maxium absorption onsets at 400 nm and 420 nm, respectively. TGA analysis indicates that 1 and 2 are stable up tomore » 110 Degree-Sign C and 210 Degree-Sign C. - Graphical abstract: Two novel one-dimensional coordination polymers, single helicate [Zn(SPh){sub 2}(TPyTA)(EG)]{sub n} (1) and zig-zag structure [Zn(SPh){sub 2}(BPyVB)]{sub n} (2), were synthesized. Solid-state UV-vis absorptions show that 1 and 2 have maxium absorption onsets at 400 nm and 420 nm, respectively. TGA analysis indicates that 1 and 2 are stable up to 110 Degree-Sign C and 210 Degree-Sign C. Highlights: Black-Right-Pointing-Pointer Two novel one-dimensional coordination polymers have been synthesized. Black-Right-Pointing-Pointer TPyTA results in helical structures in 1 while BPyVB leads to zig-zag chains in 2. Black-Right-Pointing-Pointer Solid-state UV-vis absorption spectra and TGA analysis of the title polymers were studied.« less

Detecting the Hormonal Pathways in Oilseed Rape behind Induced Systemic Resistance by Trichoderma harzianum TH12 to Sclerotinia sclerotiorum.

PubMed

Alkooranee, Jawadayn Talib; Aledan, Tamarah Raad; Ali, Ali Kadhim; Lu, Guangyuan; Zhang, Xuekun; Wu, Jiangsheng; Fu, Chunhua; Li, Maoteng

2017-01-01

Plants have the ability to resist pathogen attack after infection or treatment with biotic and abiotic elicitors. In oilseed rape plant Brassica napus AACC and in the artificially synthesized Raphanus alboglabra RRCC, the root-colonizing Trichoderma harzianum TH12 fungus triggers induced systemic resistance (ISR), and its culture filtrate (CF) triggers a systemic acquired resistance (SAR) response against infection by the Sclerotinia sclerotiorum. Salicylic acid (SA) and jasmonic acid/ethylene (JA/ET) are plant hormone signals that play important roles in the regulation of ISR and SAR. In this study, at six different time points (1, 2, 4, 6, 8 and 10 days post-infection [dpi]), six resistance genes were used as markers of signaling pathways: JA/ET signaling used AOC3, PDF1.2 and ERF2 genes, while PR-1, TGA5 and TGA6 genes were used as markers of SA signaling. The results of quantitative real-time polymerase chain reaction (qRT-PCR) showed that AOC3, PDF1.2 and ERF2 expression levels in infected leaves of AACC and RRCC increase at 1 and 2 dpi with S. sclerotiorum or inoculation with TH12. PR-1, TGA5 and TGA6 expression levels increased at 8 and 10 dpi in infected leaves. PR-1, TGA5 and TGA6 expression levels increased early in plants treated with CF in both of the healthy genotypes. Furthermore, induction of SA- and JA/ET-dependent defense decreased disease symptoms in infected leaves at different times. The results suggest that the RRCC genotype exhibits resistance to disease and that the ability of TH12 and its CF to induce systemic resistance in susceptible and resistant oilseed rape genotypes exists. In addition, the results indicate for the first time that in RRCC the SA signaling pathway is involved in resistance to necrotrophic pathogens.

Particulate morphology of waste cooking oil biodiesel and diesel in a heavy duty diesel engine

NASA Astrophysics Data System (ADS)

Hwang, Joonsik; Jung, Yongjin; Bae, Choongsik

2014-08-01

The effect of biodiesel produced from waste cooking oil (WCO) on the particulate matters (PM) of a direct injection (DI) diesel engine was experimentally investigated and compared with commercial diesel fuel. Soot agglomerates were collected with a thermophoretic sampling device installed in the exhaust pipe of the engine. The morphology of soot particles was analyzed using high resolution transmission electron microscopy (TEM). The elemental and thermogravimetric analysis (TGA) were also conducted to study chemical composition of soot particles. Based on the TEM images, it was revealed that the soot derived from WCO biodiesel has a highly graphitic shell-core arrangement compared to diesel soot. The mean size was measured from averaging 400 primary particles for WCO biodiesel and diesel respectively. The values for WCO biodiesel indicated 19.9 nm which was smaller than diesel's 23.7 nm. From the TGA results, WCO biodiesel showed faster oxidation process. While the oxidation of soot particles from diesel continued until 660°C, WCO biodiesel soot oxidation terminated at 560°C. Elemental analysis results showed that the diesel soot was mainly composed of carbon and hydrogen. On the other hand, WCO biodiesel soot contained high amount of oxygen species.

Structural, thermal and electrical characterizations of multiwalled carbon nanotubes and polyaniline composite

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

Singh, Kamal, E-mail: singhkamal204@gmail.com; Garg, Leena; Singh, Jaspal

2016-05-06

The undoped and doped composite of MWNTs (Multiwalled Carbon Nanotubes) with PANI (/Polyaniline) was prepared by chemical oxidative polymerization. The MWNTs/PANI composites have been characterized by using various techniques like Thermogravometric Analysis (TGA), Fourier transform infrared (FT-IR) spectrometer and Field emission scanning electron microscope (FE-SEM) and conductivity measurement by using two probe method. TGA results has shown that thermal stability followed the pattern undoped MWNTs/PANI composite < doped MWNTs/PANI composite. FE-SEM micrographs demonstrated the morphological changes on the surface of MWNTs as a result of composite formation. Fourier transformed infrared (FT-IR) spectra ascertained the formation of the composite. Study ofmore » electrical characteristics demonstrated that the doped MWNTs/PANI composite (1.2 × 10{sup 1} Scm{sup −1}) have better conductivity than the undoped MWNTs/PANI composite (10{sup −4} Scm{sup −1}). These CNTs based polymeric composites are of great importance in developing new nano-scale devices for future chemical, mechanical and electronic applications.« less

Graphene Oxide Filled Lignin/Starch Polymer Bionanocomposite: Structural, Physical, and Mechanical Studies.

PubMed

Aqlil, Meryem; Moussemba Nzenguet, Annie; Essamlali, Younes; Snik, Asmae; Larzek, Mohamed; Zahouily, Mohamed

2017-12-06

In this study, graphene oxide (GO) was investigated as a potential nanoreinforcing agent in starch/lignin (ST/L) biopolymer matrix. Bionanocomposite films based on ST/L blend matrix and GO were prepared by solution-casting technique of the corresponding film-forming solution. The structures, morphologies, and properties of bionanocomposite films were characterized by Fourier transform infrared (FTIR), thermal gravimetric analysis (TGA), ultraviolet-visible (UV-vis), SEM, and tensile tests. The experimental results showed that content of GO have a significant influence on the mechanical properties of the produced films. The results revealed that the interfacial interaction formed in the bionanocomposite films improved the compatibility between GO fillers and ST/L matrix. The addition of GO also reduced moisture uptake (Mu) and water vapor permeability of ST/L blend film. In addition, TGA showed that the thermal stability of bionanocomposite films was better than that of neat starch film. These findings confirmed the effectiveness of the proposed approach to produce biodegradable films with enhanced properties, which may be used in packaging applications.

Synthesis and characterization of CdS/PVA nanocomposite films

NASA Astrophysics Data System (ADS)

Wang, Hongmei; Fang, Pengfei; Chen, Zhe; Wang, Shaojie

2007-08-01

A series CdS/PVA nanocomposite films with different amount of Cd salt have been prepared by means of the in situ synthesis method via the reaction of Cd 2+-dispersed poly vinyl-alcohol (PVA) with H 2S. The as-prepared films were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), ultraviolet-visible (UV-vis) absorption, photoluminescence (PL) spectra, Fourier transform infrared spectroscope (FTIR) and thermogravimetric analysis (TGA). The XRD results indicated the formation of CdS nanoparticles with hexagonal phase in the PVA matrix. The primary FTIR spectra of CdS/PVA nanocomposite in different processing stages have been discussed. The vibrational absorption peak of Cd sbnd S bond at 405 cm -1 was observed, which further testified the generation of CdS nanoparticles. The TGA results showed incorporation of CdS nanoparticles significantly altered the thermal properties of PVA matrix. The photoluminescence and UV-vis spectroscopy revealed that the CdS/PVA films showed quantum confinement effect.

Symposium U: Thermoelectric Power Generation. Held in Boston, Massachusetts on November 26-29, 2007

DTIC Science & Technology

2008-04-01

including X - ray /electron diffraction, TGA analysis, Raman / Fourier Transform Infrared Spectroscopy, electron microscopy, Rutherford back-scattering and...Energy dispersive X - ray analysis were performed on the treated sample. The results revealed that a surface layer (from 10 nm to up to micron in...nanoparticles into a matrix of bulk Bi2Te 3 material via a hot pressing process. These nanocomposites have been examined by SEM and X - ray powder

Cell-mediated lysis of lipid vesicles containing eye muscle protein: Implications regarding pathogenesis of Graves ophthalmopathy*

PubMed Central

Kriss, Joseph P.; Mehdi, S. Qasim

1979-01-01

We prepared artificial vesicles that are lysed upon cell-mediated immunological attack by human lymphocytes. These vesicles are made from a mixture of dimyristoyl lecithin, dipalmitoyl lecithin, and cholesterol, have eye muscle membrane protein (EMP) inserted into the bilayer wall, and contain intravesicular 99mTc marker. Injury to the vesicular membrane was assessed by measurement of 99mTc release. Thyroglobulin (Tg) and Tg-anti-Tg complex (TgA) bind to EMP-vesicles to an extent equal to or greater than to native eye muscle membranes in vitro; this binding requires the presence of normal human IgG. The role of Tg, TgA, IgG, and peripheral blood lymphocytes in altering membrane permeability was analyzed. Incubation of vesicles for up to 3 hr alone, with added IgG alone, or with further addition of Tg or TgA did not result in 99mTc release. Addition of lymphocytes from normal donors to the above four preparations showed release in the presence of TgA. Lymphocytes from each of eight patients with Graves ophthalmopathy caused release not only in the presence of TgA, but also in the presence of Tg. Separation of a patient's lymphocytes into high- and low-affinity rosette-formers (T and K cells, respectively) showed that cell-mediated vesicle lysis in the presence of TgA was greater with K cells than with T cells, while vesicle lysis in the presence of Tg was greater with T cells than with K cells. Vesicles made with inserted Tg but lacking EMP were not lysed by such T cells. Lymphocytes failed to induce permeability changes in vesicles containing other inserted proteins obtained from human nonextraocular muscle, liver, spleen, or adrenal, even if Tg or TgA were present. The results support the concept that muscle cell damage in Graves ophthalmopathy is immunological, cell-mediated, and of two types: (i) K lymphocytes reacting to immune complex, TgA, on the eye muscle cell surface (i.e., antibody-dependent cytotoxicity) and (ii) sensitized T lymphocytes reacting to Tg on the eye muscle cell surface. An antigenic role for EMP is possible, but has not been unequivocally proven. PMID:88053

Kinetics of Cold-Cap Reactions for Vitrification of Nuclear Waste Glass Based on Simultaneous Differential Scanning Calorimetry - Thermogravimetry (DSC-TGA) and Evolved Gas Analysis (EGA)

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

Rodriguez, Carmen P.; Pierce, David A.; Schweiger, Michael J.

2013-12-03

For vitrifying nuclear waste glass, the feed, a mixture of waste with glass-forming and modifying additives, is charged onto the cold cap that covers 90-100% of the melt surface. The cold cap consists of a layer of reacting molten glass floating on the surface of the melt in an all-electric, continuous glass melter. As the feed moves through the cold cap, it undergoes chemical reactions and phase transitions through which it is converted to molten glass that moves from the cold cap into the melt pool. The process involves a series of reactions that generate multiple gases and subsequent massmore » loss and foaming significantly influence the mass and heat transfers. The rate of glass melting, which is greatly influenced by mass and heat transfers, affects the vitrification process and the efficiency of the immobilization of nuclear waste. We studied the cold-cap reactions of a representative waste glass feed using both the simultaneous differential scanning calorimetry thermogravimetry (DSC-TGA) and the thermogravimetry coupled with gas chromatography-mass spectrometer (TGA-GC-MS) as complementary tools to perform evolved gas analysis (EGA). Analyses from DSC-TGA and EGA on the cold-cap reactions provide a key element for the development of an advanced cold-cap model. It also helps to formulate melter feeds for higher production rate.« less

Murein Lytic Enzyme TgaA of Bifidobacterium bifidum MIMBb75 Modulates Dendritic Cell Maturation through Its Cysteine- and Histidine-Dependent Amidohydrolase/Peptidase (CHAP) Amidase Domain

PubMed Central

Zanoni, Ivan; Balzaretti, Silvia; Miriani, Matteo; Taverniti, Valentina; De Noni, Ivano; Presti, Ilaria; Stuknyte, Milda; Scarafoni, Alessio; Arioli, Stefania; Iametti, Stefania; Bonomi, Francesco; Mora, Diego; Karp, Matti; Granucci, Francesca

2014-01-01

Bifidobacteria are Gram-positive inhabitants of the human gastrointestinal tract that have evolved close interaction with their host and especially with the host's immune system. The molecular mechanisms underlying such interactions, however, are largely unidentified. In this study, we investigated the immunomodulatory potential of Bifidobacterium bifidum MIMBb75, a bacterium of human intestinal origin commercially used as a probiotic. Particularly, we focused our attention on TgaA, a protein expressed on the outer surface of MIMBb75's cells and homologous to other known bacterial immunoactive proteins. TgaA is a peptidoglycan lytic enzyme containing two active domains: lytic murein transglycosylase (LT) and cysteine- and histidine-dependent amidohydrolase/peptidase (CHAP). We ran immunological experiments stimulating dendritic cells (DCs) with the B. bifidum MIMBb75 and TgaA, with the result that both the bacterium and the protein activated DCs and triggered interleukin-2 (IL-2) production. In addition, we observed that the heterologous expression of TgaA in Bifidobacterium longum transferred to the bacterium the ability to induce IL-2. Subsequently, immunological experiments performed using two purified recombinant proteins corresponding to the single domains LT and CHAP demonstrated that the CHAP domain is the immune-reactive region of TgaA. Finally, we also showed that TgaA-dependent activation of DCs requires the protein CD14, marginally involves TRIF, and is independent of Toll-like receptor 4 (TLR4) and MyD88. In conclusion, our study suggests that the bacterial CHAP domain is a novel microbe-associated molecular pattern actively participating in the cross talk mechanisms between bifidobacteria and the host's immune system. PMID:24814791

Metabolic alterations and neurodevelopmental outcome of infants with transposition of the great arteries.

PubMed

Park, I Sook; Yoon, S Young; Min, J Yeon; Kim, Y Hwue; Ko, J Kok; Kim, K Soo; Seo, D Man; Lee, J Hee

2006-01-01

Abnormal neurodevelopment has been reported for infants who were born with transposition of the great arteries (TGA) and underwent arterial switch operation (ASO). This study evaluates the cerebral metabolism of TGA infants at birth and before ASO and neurodevelopment 1 year after ASO. Proton magnetic resonance spectroscopy (1H-MRS) was performed on 16 full-term TGA brains before ASO within 3-6 days after birth. The brain metabolite ratios of [NAA/Cr], [Cho/Cr], and [mI/Cr] evaluated measured. Ten infants were evaluated at 1 year using the Bayley Scales of Infants Development II (BSED II). Cerebral metabolism of infants with TGA was altered in parietal white matter (PWM) and occipital gray matter (OGM) at birth before ASO. One year after ASO, [Cho/Cr] in PWM remained altered, but all metabolic ratios in OGM were normal. The results of BSID II at 1 year showed delayed mental and psychomotor development. This delayed neurodevelopmental outcome may reflect consequences of the altered cerebral metabolism in PWM measured by 1H-MRS. It is speculated that the abnormal hemodynamics due to TGA in utero may be responsible for the impaired cerebral metabolism and the subsequent neurodevelopmental deficit.

Graph theory analysis of cortical thickness networks in adolescents with d-transposition of the great arteries.

PubMed

Watson, Christopher G; Stopp, Christian; Newburger, Jane W; Rivkin, Michael J

2018-02-01

Adolescents with d-transposition of the great arteries (d-TGA) who had the arterial switch operation in infancy have been found to have structural brain differences compared to healthy controls. We used cortical thickness measurements obtained from structural brain MRI to determine group differences in global brain organization using a graph theoretical approach. Ninety-two d-TGA subjects and 49 controls were scanned using one of two identical 1.5-Tesla MRI systems. Mean cortical thickness was obtained from 34 regions per hemisphere using Freesurfer. A linear model was used for each brain region to adjust for subject age, sex, and scanning location. Structural connectivity for each group was inferred based on the presence of high inter-regional correlations of the linear model residuals, and binary connectivity matrices were created by thresholding over a range of correlation values for each group. Graph theory analysis was performed using packages in R. Permutation tests were performed to determine significance of between-group differences in global network measures. Within-group connectivity patterns were qualitatively different between groups. At lower network densities, controls had significantly more long-range connections. The location and number of hub regions differed between groups: controls had a greater number of hubs at most network densities. The control network had a significant rightward asymmetry compared to the d-TGA group at all network densities. Using graph theory analysis of cortical thickness correlations, we found differences in brain structural network organization among d-TGA adolescents compared to controls. These may be related to the white matter and gray matter differences previously found in this cohort, and in turn may be related to the cognitive deficits this cohort presents.

Features of the incorporation of single and double based powders within emulsion explosives

NASA Astrophysics Data System (ADS)

Ribeiro, J. B.; Mendes, R.; Tavares, B.; Louro, C.

2014-05-01

In this work, features of the thermal and detonation behaviour of compositions resulting from the mixture of single and double based powders within ammonium nitrate based emulsion explosives are shown. Those features are portrayed through results of thermodynamic-equilibrium calculations of the detonation velocity, the chemical compatibility assessment through differential thermal analysis [DTA] and thermo gravimetric analysis [TGA], the experimental determination of the detonation velocity and a comparative evaluation of the shock sensitivity using a modified version of the "gap-test". DTA/TGA results for the compositions and for the individual components overlap until the beginning of the thermal decomposition which is an indication of the absence of formation of any new chemical species and so of the compatibility of the components of the compositions. After the beginning of the thermal decomposition it can be seen that the rate of mass loss is much higher for the compositions with powder than for the one with sole emulsion explosive. Both, theoretical and experimental, values of the detonation velocity have been shown to be higher for the powdered compositions than for the sole emulsion explosive. Shock sensitivity assessments have ended-up with a slightly bigger sensitivity for the compositions with double based powder when compared to the single based compositions or to the sole emulsion.

Thermal and Mechanical Behavior of Hybrid Polymer Nanocomposite Reinforced with Graphene Nanoplatelets

PubMed Central

Le, Minh-Tai; Huang, Shyh-Chour

2015-01-01

In the present investigation, we successfully fabricate a hybrid polymer nanocomposite containing epoxy/polyester blend resin and graphene nanoplatelets (GNPs) by a novel technique. A high intensity ultrasonicator is used to obtain a homogeneous mixture of epoxy/polyester resin and graphene nanoplatelets. This mixture is then mixed with a hardener using a high-speed mechanical stirrer. The trapped air and reaction volatiles are removed from the mixture using high vacuum. The hot press casting method is used to make the nanocomposite specimens. Tensile tests, dynamic mechanical analysis (DMA) and thermogravimetric analysis (TGA) are performed on neat, 0.2 wt %, 0.5 wt %, 1 wt %, 1.5 wt % and 2 wt % GNP-reinforced epoxy/polyester blend resin to investigate the reinforcement effect on the thermal and mechanical properties of the nanocomposites. The results of this research indicate that the tensile strength of the novel nanocomposite material increases to 86.8% with the addition of a ratio of graphene nanoplatelets as low as 0.2 wt %. DMA results indicate that the 1 wt % GNP-reinforced epoxy/polyester nanocomposite possesses the highest storage modulus and glass transition temperature (Tg), as compared to neat epoxy/polyester or the other nanocomposite specimens. In addition, TGA results verify thethermal stability of the experimental specimens, regardless of the weight percentage of GNPs. PMID:28793521

Persistent institutional difficulties in surgery for transposition of the great arteries in guatemala: analysis with the aristotle basic and comprehensive scores.

PubMed

Leon-Wyss, Juan; Lo Rito, Mauro; Barnoya, Joaquin; Castañeda, Aldo R

2011-07-01

Background. Neonates with complex congenital cardiac lesions are largely inadequately managed in Guatemala. Methods. Between 1997 and 2009, 79 patients who underwent operations for transposition of the great arteries were identified; 51 (63.3%) had an arterial switch operation (ASO) and 28 (36%) an atrial switch operation (ATSO). The Aristotle Basic Complexity score (ABC score) and the Aristotle Comprehensive Complexity score (ACC score) have been used to aid in the evaluation of quality of care associated with pediatric cardiac surgery by adjusting for operative complexity. Results. In-hospital mortality was 47% for the ASO and 25% for the ATSO group; 36.7% were beyond 1 month of age and many exhibited increased preoperative risk factors. The mean ABC score was 9.75 ± 0.89 and the ACC score was 12.12 ± 2.7, with a mean 2.36-point increase (P < .05). Comparing survivors and nonsurvivors with both scores, significant differences were identified (ABC: P < .04 and ACC: P < .02). Conclusion. During this 13-year period, a low volume of surgery for transposition of the great arteries (TGA) was performed at our institution with a relatively high surgical mortality. Many patients with TGA in Guatemala are either never referred for surgery or referred late. Strategies to improve outcomes for neonates with TGA in Guatemala must include increases in early diagnosis countrywide and prompt referral to our unit. Based on the larger number of neonates with TGA that would be referred to our center, we anticipate that this strategy should substantially improve surgical outcomes and favor overall team-related skills.

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

Tang, Mingyi; Xu, Xiaoyang, E-mail: xiaoyangxu2012@163.com; Wu, Tao

Highlights: • Graphene oxide (GO) was modified by chemical reactions to functionalized GO (FGO). • The FGOs and the GO were then subjected to in situ free radical polymerization. • Hydroxyl groups of GO were the most reactive grafting sites. - Abstract: Graphene oxide (GO) was modified using chemical reactions to obtain three types of functionalized GO sheets (FGO). The FGO sheets and the GO were then subjected to in situ free radical polymerization in order to study the grafting polymerization. The FGO and grafted-.FGO were analyzed with Fourier transform infrared spectroscopy, scanning electronic microscopy, thermo-gravimetric analysis (TGA) and X-raymore » photoelectron spectroscopy (XPS). The grafting percentages in the materials were calculated using the TGA and XPS results. The FGO sheets with different functional groups exhibited different grafting abilities, and hydroxyl groups were proven to be the most reactive grafting sites for the in situ free radical grafting polymerization of polyacrylamide.« less

Nitrate induction of root hair density is mediated by TGA1/TGA4 and CPC transcription factors in Arabidopsis thaliana.

PubMed

Canales, Javier; Contreras-López, Orlando; Álvarez, José M; Gutiérrez, Rodrigo A

2017-10-01

Root hairs are specialized cells that are important for nutrient uptake. It is well established that nutrients such as phosphate have a great influence on root hair development in many plant species. Here we investigated the role of nitrate on root hair development at a physiological and molecular level. We showed that nitrate increases root hair density in Arabidopsis thaliana. We found that two different root hair defective mutants have significantly less nitrate than wild-type plants, suggesting that in A. thaliana root hairs have an important role in the capacity to acquire nitrate. Nitrate reductase-null mutants exhibited nitrate-dependent root hair phenotypes comparable with wild-type plants, indicating that nitrate is the signal that leads to increased formation of root hairs. We examined the role of two key regulators of root hair cell fate, CPC and WER, in response to nitrate treatments. Phenotypic analyses of these mutants showed that CPC is essential for nitrate-induced responses of root hair development. Moreover, we showed that NRT1.1 and TGA1/TGA4 are required for pathways that induce root hair development by suppression of longitudinal elongation of trichoblast cells in response to nitrate treatments. Our results prompted a model where nitrate signaling via TGA1/TGA4 directly regulates the CPC root hair cell fate specification gene to increase formation of root hairs in A. thaliana. © 2017 The Authors The Plant Journal © 2017 John Wiley & Sons Ltd.

Management of Systemic Right Ventricular Failure in Patients With Congenitally Corrected Transposition of the Great Arteries.

PubMed

Filippov, Aleksei A; Del Nido, Pedro J; Vasilyev, Nikolay V

2016-10-25

In recent decades, significant progress has been made in the diagnosis and management of congenitally corrected transposition of the great arteries (ccTGA). Nevertheless, gradual dysfunction and failure of the right ventricle (RV) in the systemic circulation remain the main contributors to mortality and disability for patients with ccTGA, especially after adolescence. Anatomic repair of ccTGA effectively resolves the problem of failure of the systemic RV and has good early and midterm results. However, this strategy is applicable primarily in infants and children up to their teens and has associated risks and limitations, and new challenges can arise in the late postoperative period. Patients with ccTGA manifesting progressive systemic RV dysfunction beyond adolescence represent the major challenge. Several palliative options such as cardiac resynchronization therapy, tricuspid valve repair or replacement, pulmonary artery banding, and implantation of an assist device into the systemic RV can be used to improve functional status and to delay the progression of ventricular dysfunction in patients who are not suitable for anatomic correction of ccTGA. For adult patients with severe systemic RV failure, heart transplantation currently remains the only long-term lifesaving procedure, although donor organ availability remains one of the most limiting factors in this type of therapy. This review focuses on current surgical and medical strategies and interventional options for the prevention and management of systemic RV failure in adults and children with ccTGA. © 2016 American Heart Association, Inc.

Dynamic Moisture Sorption and Desorption in Fumed Silica-filled Silicone Foam

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

Trautschold, Olivia Carol

Characterizing dynamic moisture sorption and desorption in fumed silica-filled silicone foam is necessary for determining material compatibilities and life predictions, particularly in sealed environments that may be exposed to a range of environmental conditions. Thermogravimetric analysis (TGA) and near infrared spectroscopy (NIR) were performed on S5470 fumed silica-filled silicone foam to determine the weight percent of moisture at saturation. Additionally, TGA was used to determine the time, temperature, and relative humidity levels required for sorption and desorption of physisorbed moisture in S5470.

Nanocomposite materials based on poly(vinyl chloride) and bovine serum albumin modified ZnO through ultrasonic irradiation as a green technique: Optical, thermal, mechanical and morphological properties.

PubMed

Mallakpour, Shadpour; Darvishzadeh, Marzieh

2018-03-01

In this project, physicochemical properties of poly(vinyl chloride) (PVC) reinforced by ZnO nanoparticles (NPs) were studied. Firstly, ZnO NPs were modified with bovine serum albumin (BSA) as an organo-modifier and biocompatible substance through ultrasound irradiation as environmental friendly, low cost and rapid means. Nanocomposite (NC) films were prepared by loadings of various ratios of ZnO/BSA NPs (3, 6 and 9wt%) inside the PVC. Structural morphology and physical properties of the ZnO-BSA NPs and NC films were investigated via Fourier transform infrared spectroscopy, X-ray diffraction, thermogravimetric analysis (TGA), transmission electron microscopy and field emission scanning electron microscopy. According to the obtained information from the TGA, an increase in the thermal stability can be clearly observed. Also the results of contact angle analysis indicated with increasing percent of ZnO/BSA NPs into PVC the hydrophilic behaviors of NCs were increased. Copyright © 2017 Elsevier B.V. All rights reserved.

Highly crystalline zinc incorporated hydroxyapatite nanorods' synthesis, characterization, thermal, biocompatibility, and antibacterial study

NASA Astrophysics Data System (ADS)

Udhayakumar, Gayathri; Muthukumarasamy, N.; Velauthapillai, Dhayalan; Santhosh, Shanthi Bhupathi

2017-10-01

Highly crystalline zinc incorporated hydroxyapatite (Zn-HAp) nanorods have been synthesized using microwave irradiation method. To improve bioactivity and crystallinity of pure HAp, zinc was incorporated into it. As-synthesized samples were characterized by Fourier transform-infrared spectroscopy (FT-IR), X-ray diffraction, field-emission scanning electron microscopy (FESEM), energy dispersive X-ray analysis (EDAX), high-resolution transmission electron microscopy (HRTEM), and the thermal and crystallinity behavior of Zn-HAp nanoparticle were studied by thermogravimetry (TGA) and differential scanning calorimetry (DSC). Antibacterial activity of the as-synthesized nanorods was evaluated against two prokaryotic strains ( Escherichia coli and Staphylococcus aureus). The FT-IR studies show the presence of hydroxide and phosphate functional groups. HRTEM and FESEM images showed highly crystalline rod-shaped nanoparticles with the diameter of about 50-60 nm. EDAX revealed the presence of Ca, Zn, P, and O in the prepared samples. The crystallinity and thermal stability were further confirmed by TGA-DSC analysis. The biocompatibility evaluation results promoted that the Zn-HAp nanorods are biologically active apatites and potentially promising bone-substitute biomaterials for orthopaedic application.

Investigation on thermochemical behaviour of low rank Malaysian coal, oil palm biomass and their blends during pyrolysis via thermogravimetric analysis (TGA).

PubMed

Idris, Siti Shawalliah; Abd Rahman, Norazah; Ismail, Khudzir; Alias, Azil Bahari; Abd Rashid, Zulkifli; Aris, Mohd Jindra

2010-06-01

This study aims to investigate the behaviour of Malaysian sub-bituminous coal (Mukah Balingian), oil palm biomass (empty fruit bunches (EFB), kernel shell (PKS) and mesocarp fibre (PMF)) and their respective blends during pyrolysis using thermogravimetric analysis (TGA). The coal/palm biomass blends were prepared at six different weight ratios and experiments were carried out under dynamic conditions using nitrogen as inert gas at various heating rates to ramp the temperature from 25 degrees C to 900 degrees C. The derivative thermogravimetric (DTG) results show that thermal decomposition of EFB, PMF and PKS exhibit one, two and three distinct evolution profiles, respectively. Apparently, the thermal profiles of the coal/oil palm biomass blends appear to correlate with the percentage of biomass added in the blends, thus, suggesting lack of interaction between the coal and palm biomass. First-order reaction model were used to determine the kinetics parameters for the pyrolysis of coal, palm biomass and their respective blends. (c) 2010 Elsevier Ltd. All rights reserved.

Synthesis and characterization of some metal oxide nanocrystals by microwave irradiation

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

Rashad, M.; Gaber, A.; Abdelrahim, M. A.

2013-12-16

Copper oxide and cobalt oxide (CuO, Co3O4) nanocrystals (NCs) have been successfully prepared in a short time using microwave irradiation. The resulted powders of nanocrystals (NCs) were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). Thermogravimetric analysis (TGA) measurements are also studied. Fourier-transform infrared (FT-IR) and UV–visible absorption spectroscopy of both kind of nanoparticels are illustrated. Optical absorption analysis indicated the direct band gap for both kinds of nanocrystals.

Three pharmaceuticals cocrystals of adefovir: Syntheses, structures and dissolution study

NASA Astrophysics Data System (ADS)

Zhang, Xiaoming; Sun, Fuxing; Zhang, Tingting; Jia, Jiangtao; Su, Hongmin; Wang, Chenhui; Zhu, Guangshan

2015-11-01

We report here three novel cocrystals, which are composed of adefovir as the API (Active Pharmaceutical Ingredient) with p-aminobenzoic acid (1, 2C8H12N5O4P·C7H6NO2·3H2O), 3,5-dihydroxybenzoic acid (2, C8H12N5O4P·C7H6O4·H2O) and 2,6-pyridinedicarboxlic acid (3, C8H12N5O4P·C7H5NO4) as CCFs (cocrystal formers) respectively by crystal engineering strategy. Their structures were characterized by single crystal X-ray diffraction, powder X-ray diffraction (PXRD) analysis, thermogravimetric analyses (TGA), elemental analysis (EA) and infrared spectral analysis (IR). The analysis of single crystal X-ray diffraction demonstrate that cocrystal 1 and 2 form a strong hydrogen-bonded assembly through the phosphoric acids of API with water in the lattice and carboxylic acids of CCF respectively. Cocrystal 3 is formed in which the phosphoric acid groups of API are also held by the carboxylic acid groups of CCF. The PXRD results indicate their high purity of as-synthesized samples. The TGA, EA, IR and dissolution study of API and the cocrystals were also measured and discussed.

Cerebral oximetry monitoring in the management of severe hypoxaemia associated with transposition of the great arteries with balloon atrial septostomy.

PubMed

Pérez Moreno, J C; Nájera Losada, D C; Sanabria Carretero, P; Paredes Lacave, Á; Benito Bartolomé, F

2018-05-01

Transposition of the great arteries (D-TGA) is one of the most common congenital heart diseases requiring neonatal surgical intervention. In the desperately ill neonate with TGA and the resultant hypoxaemia, acidemia, and congestive heart failure, improvement is often obtained with balloon atrial septostomy (BAS). Current methods employed to evaluate oxygen delivery and tissue consumption are frequently nonspecific. Near infrared spectroscopy (NIRS) allows a continuous non-invasive measurement of tissue oxygenation which reflects perfusion status in real time. Because little is known about the direct effect of BAS on the neonatal brain and on cerebral oxygenation, we measured the effectiveness of BAS in two patients with D-TGA using NIRS before and after BAS. We concluded BAS improves cerebral oxygen saturation in neonates with D-TGA. Copyright © 2017 Sociedad Española de Anestesiología, Reanimación y Terapéutica del Dolor. Publicado por Elsevier España, S.L.U. All rights reserved.

Jugular veins in transient global amnesia: innocent bystanders.

PubMed

Baracchini, Claudio; Tonello, Simone; Farina, Filippo; Viaro, Federica; Atzori, Matteo; Ballotta, Enzo; Manara, Renzo

2012-09-01

Transient global amnesia (TGA) has been associated with an increased prevalence of internal jugular valve insufficiency and many patients report Valsalva-associated maneuvers before TGA onset. These findings have led to the assumption of hemodynamic alterations in intracranial veins inducing focal hippocampal ischemia. We investigated this hypothesis in patients with TGA and control subjects. Seventy-five patients with TGA and 75 age- and sex-matched healthy subjects were enrolled into a cross-sectional study. Extracranial and transcranial high-resolution venous echo-color-Doppler sonography was performed blindly in all patients and control subjects. Blood flow direction and velocities were recorded at the internal jugular veins, basal veins of Rosenthal, and vein of Galen, both at rest and during Valsalva-associated maneuvers. Mean age of patients with TGA was 60.3±8.0 years (median, 60 years; range, 44-78 years); 44 (59%) were female (female/male ratio: 1.42). Internal jugular valve insufficiency (left, right, or bilateral) was found to be more frequent in patients with TGA than in control subjects: 53 (70.7%) versus 22 (29.3%; P<0.05). Blood flow velocities in the deep cerebral veins of patients with TGA did not differ from control subjects both at rest and during Valsalva-associated maneuvers. Intracranial venous reflux was neither observed in patients with TGA nor in control subjects despite unilateral or bilateral internal jugular valve insufficiency during prolonged and maximal Valsalva-associated maneuvers. This study, although confirming the association between TGA and internal jugular valve insufficiency, challenges the hypothesis that cerebral venous congestion plays a significant role in the pathogenesis of TGA.

Fluorescent reversible regulation based on the interactions of topotecan hydrochloride, neutral red and quantum dots

NASA Astrophysics Data System (ADS)

Wang, Linlin; Shen, Yizhong; Liu, Shaopu; Yang, Jidong; Liang, Wanjun; Li, Dan; He, Youqiu

2015-02-01

The interactions of topotecan hydrochloride (THC), neutral red (NR) and thioglycolic acid (TGA) capped CdTe/CdS quantum dots (QDs) built a solid base for the controlling of the fluorescent reversible regulation of the system. This study was developed by means of ultraviolet-visible (UV-vis) absorption, fluorescence (FL), resonance Rayleigh scattering (RRS) spectroscopy and transmission electron microscopy (TEM). Corresponding experimental results revealed that the fluorescence of TGA-CdTe/CdS QDs could be effectively quenched by NR, while the RRS of the QDs enhanced gradually with the each increment of NR concentration. After the addition of THC, the strong covalent conjugation between NR and THC which was in carboxylate state enabled NR to be dissociated from the surface of TGA-CdTe/CdS QDs to form more stable complex with THC, thereby enhancing the fluorescence of the TGA-CdTe/CdS QDs-NR system. What is more, through analyzing the optical properties and experimental data of the reaction between TGA-CdTe/CdS QDs and NR, the possible reaction mechanism of the whole system was discussed. This combination of multiple spectroscopic techniques could contribute to the investigation for the fluorescent reversible regulation of QDs and a method could also be established to research the interactions between camptothecin drugs and dyes.

Effect of maternal behavior on regulation during feeding in healthy infants and infants with transposition

PubMed Central

Harrison, Tondi M.

2010-01-01

Objective To compare physiologic regulation and the effect of maternal sensitive caregiving during feeding on physiologic regulation in healthy infants and in infants with transposition of the great arteries (TGA). Design Descriptive, two group, repeated measures. Setting Three children's hospitals in the Midwest. Participants A convenience sample of 15 infants with TGA matched with 16 healthy infants. Methods Measures of physiologic regulation before, during, and after feeding and quality of maternal affect and behavior during feeding were collected post-operatively at two weeks and two months of age. Results At two weeks, infants with TGA demonstrated impaired physiologic regulation with feedings when compared with healthy infants. Healthy infants of more sensitive mothers were more likely to demonstrate a physiologically adaptive response during feeding. Maternal effect on physiologic regulation was not observed in infants with TGA. No differences between groups were found at two months. Conclusions For infants with TGA, effects of surgical recovery and limited contact with their mothers relative to healthy infants may have outweighed the supportive effect of maternal sensitivity during feeding in the early weeks of life. Further research is needed to identify ways of enhancing the regulatory effect of maternal behavior on infants with heart defects. PMID:19614886

Identification of Non-HLA Genes Associated with Celiac Disease and Country-Specific Differences in a Large, International Pediatric Cohort

PubMed Central

Sharma, Ashok; Liu, Xiang; Hadley, David; Hagopian, William; Liu, Edwin; Chen, Wei-Min; Onengut-Gumuscu, Suna; Simell, Ville; Rewers, Marian; Ziegler, Anette-G.; Lernmark, Åke; Simell, Olli; Toppari, Jorma; Krischer, Jeffrey P.; Akolkar, Beena; Rich, Stephen S.; Agardh, Daniel; She, Jin-Xiong

2016-01-01

Objectives There are significant geographical differences in the prevalence and incidence of celiac disease that cannot be explained by HLA alone. More than 40 loci outside of the HLA region have been associated with celiac disease. We investigated the roles of these non-HLA genes in the development of tissue transglutaminase autoantibodies (tTGA) and celiac disease in a large international prospective cohort study. Methods A total of 424,788 newborns from the US and European general populations and first-degree relatives with type 1 diabetes were screened for specific HLA genotypes. Of these, 21,589 carried 1 of the 9 HLA genotypes associated with increased risk for type 1 diabetes and celiac disease; we followed 8676 of the children in a 15 y prospective follow-up study. Genotype analyses were performed on 6010 children using the Illumina ImmunoChip. Levels of tTGA were measured in serum samples using radio-ligand binding assays; diagnoses of celiac disease were made based on persistent detection of tTGA and biopsy analysis. Data were analyzed using Cox proportional hazards analyses. Results We found 54 single-nucleotide polymorphisms (SNPs) in 5 genes associated with celiac disease (TAGAP, IL18R1, RGS21, PLEK, and CCR9) in time to celiac disease analyses (10−4>P>5.8x10−6). The hazard ratios (HR) for the SNPs with the smallest P values in each region were 1.59, 1.45, 2.23, 2.64, and 1.40, respectively. Outside of regions previously associated with celiac disease, we identified 10 SNPs in 8 regions that could also be associated with the disease (P<10−4). A SNP near PKIA (rs117128341, P = 6.5x10−8, HR = 2.8) and a SNP near PFKFB3 (rs117139146, P<2.8x10−7, HR = 4.9) reached the genome-wide association threshold in subjects from Sweden. Analyses of time to detection of tTGA identified 29 SNPs in 2 regions previously associated with celiac disease (CTLA4, P = 1.3x10−6, HR = 0.76 and LPP, P = 2.8x10−5, HR = .80) and 6 SNPs in 5 regions not previously associated with celiac disease (P<10−4); non-HLA genes are therefore involved in development of tTGA. Conclusions In conclusion, using a genetic analysis of a large international cohort of children, we associated celiac disease development with 5 non-HLA regions previously associated with the disease and 8 regions not previously associated with celiac disease. We identified 5 regions associated with development of tTGA. Two loci associated with celiac disease progression reached a genome-wide association threshold in subjects from Sweden. PMID:27015091

Chitosan-thioglycolic acid as a versatile antimicrobial agent.

PubMed

Geisberger, Georg; Gyenge, Emina Besic; Hinger, Doris; Käch, Andres; Maake, Caroline; Patzke, Greta R

2013-04-08

As functionalized chitosans hold great potential for the development of effective and broad-spectrum antibiotics, representative chitosan derivatives were tested for antimicrobial activity in neutral media: trimethyl chitosan (TMC), carboxy-methyl chitosan (CMC), and chitosan-thioglycolic acid (TGA; medium molecular weight: MMW-TGA; low molecular weight: LMW-TGA). Colony forming assays indicated that LMW-TGA displayed superior antimicrobial activity over the other derivatives tested: a 30 min incubation killed 100% Streptococcus sobrinus (Gram-positive bacteria) and reduced colony counts by 99.99% in Neisseria subflava (Gram-negative bacteria) and 99.97% in Candida albicans (fungi). To elucidate LMW-TGA effects at the cellular level, microscopic studies were performed. Use of fluorescein isothiocyanate (FITC)-labeled chitosan derivates in confocal microscopy showed that LMW-TGA attaches to microbial cell walls, while transmission electron microscopy indicated that this derivative severely affects cell wall integrity and intracellular ultrastructure in all species tested. We therefore propose LMW-TGA as a promising and effective broad-band antimicrobial compound.

Spectroscopic and thermogravimetric study of nickel sulfaquinoxaline complex

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

Tailor, Sanjay M., E-mail: sanjay-tailor10@yahoo.com; Patel, Urmila H.

2016-05-06

The ability of sulfaquinoxaline (4-Amino-N-2-quinoxalinylbenzenesulfonamide) to form metal complexes are investigated. The nickel complex of sulfaquinoxaline is prepared by reflux method and characterized by CHN analysis and IR spectra. The results of IR spectral data suggest that the binding of nickel atom to the sulfonamidic nitrogen are in good agreement. The thermogravimetric analysis (TGA), differential thermal analysis (DTA) and differential thermogravimetric (DTG) analysis of nickel sulfaquinoxaline are carried out from ambient temperature to 750°C in inert nitrogen atmosphere. The activation energy, enthalpy, entropy and Gibbs free energy of nickel sulfaquinoxaline complex is determined from the thermal curves using Broido method.more » The results are reported in this paper.« less

Experimental investigation into the oxidation reactivity and nanostructure of particulate matter from diesel engine fuelled with diesel/polyoxymethylene dimethyl ethers blends

PubMed Central

Yang, Hao; Li, Xinghu; Wang, Yan; Mu, Mingfei; Li, Xuehao; Kou, Guiyue

2016-01-01

This paper focuses on oxidation reactivity and nanostructural characteristics of particulate matter (PM) emitted from diesel engine fuelled with different volume proportions of diesel/polyoxymethylene dimethyl ethers (PODEn) blends (P0, P10 and P20). PM was collected using a metal filter from the exhaust manifold. The collected PM samples were characterized using thermogravimetric analysis (TGA), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Raman spectroscopy. The TGA results indicated that the PM produced by P20 had the highest moisture and volatility contents and the fastest oxidation rate of solid carbon followed by P10 and P0 derived PM. SEM analysis showed that PM generated from P20 was looser with a lower mean value than PM emitted from P10 and P0. Quantitative analysis of high-resolution TEM images presented that fringe length was reduced along with increased separation distance and tortuosity with an increase in PODEn concentration. These trends improved the oxidation reactivity. According to Raman spectroscopy data, the intensity, full width at half-maximum and intensity ratio of the bands also changed demonstrating that PM nanostructure disorder was correlated with a faster oxidation rate. The results show the use of PODEn affects the oxidation reactivity and nanostructure of PM that is easier to oxidize. PMID:27876872

Experimental investigation into the oxidation reactivity and nanostructure of particulate matter from diesel engine fuelled with diesel/polyoxymethylene dimethyl ethers blends

NASA Astrophysics Data System (ADS)

Yang, Hao; Li, Xinghu; Wang, Yan; Mu, Mingfei; Li, Xuehao; Kou, Guiyue

2016-11-01

This paper focuses on oxidation reactivity and nanostructural characteristics of particulate matter (PM) emitted from diesel engine fuelled with different volume proportions of diesel/polyoxymethylene dimethyl ethers (PODEn) blends (P0, P10 and P20). PM was collected using a metal filter from the exhaust manifold. The collected PM samples were characterized using thermogravimetric analysis (TGA), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Raman spectroscopy. The TGA results indicated that the PM produced by P20 had the highest moisture and volatility contents and the fastest oxidation rate of solid carbon followed by P10 and P0 derived PM. SEM analysis showed that PM generated from P20 was looser with a lower mean value than PM emitted from P10 and P0. Quantitative analysis of high-resolution TEM images presented that fringe length was reduced along with increased separation distance and tortuosity with an increase in PODEn concentration. These trends improved the oxidation reactivity. According to Raman spectroscopy data, the intensity, full width at half-maximum and intensity ratio of the bands also changed demonstrating that PM nanostructure disorder was correlated with a faster oxidation rate. The results show the use of PODEn affects the oxidation reactivity and nanostructure of PM that is easier to oxidize.

Preparation, characterisation and viability of encapsulated Trichoderma harzianum UPM40 in alginate-montmorillonite clay.

PubMed

Adzmi, Fariz; Meon, Sariah; Musa, Mohamed Hanafi; Yusuf, Nor Azah

2012-01-01

Microencapsulation is a process by which tiny parcels of an active ingredient are packaged within a second material for the purpose of shielding the active ingredient from the surrounding environment. This study aims to determine the ability of the microencapsulation technique to improve the viability of Trichoderma harzianum UPM40 originally isolated from healthy groundnut roots as effective biological control agents (BCAs). Alginate was used as the carrier for controlled release, and montmorillonite clay (MMT) served as the filler. The encapsulated Ca-alginate-MMT beads were characterised using Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and scanning electron microscopy (SEM). The FTIR results showed the interaction between the functional groups of alginate and MMT in the Ca-alginate-MMT beads. Peaks at 1595, 1420 and 1020 cm(-1) characterised alginate, and peaks at 1028 and 453 cm(-1) characterised MMT; both sets of peaks appeared in the Ca-alginate-MMT FTIR spectrum. The TGA analysis showed an improvement in the thermal stability of the Ca-alginate-MMT beads compared with the alginate beads alone. SEM analysis revealed a homogeneous distribution of the MMT particles throughout the alginate matrix. T. harzianum UPM40 was successfully encapsulated in the Ca-alginate-MMT beads. Storage analysis of the encapsulated T. harzianum UPM40 showed that the low storage temperature of 5°C resulted in significantly (p < 0.05) better storage compared with room temperature (30°C).

Clinical features of celiac disease: a prospective birth cohort.

PubMed

Agardh, Daniel; Lee, Hye-Seung; Kurppa, Kalle; Simell, Ville; Aronsson, Carin Andrén; Jörneus, Ola; Hummel, Michael; Liu, Edwin; Koletzko, Sibylle

2015-04-01

To investigate clinical features of celiac disease (CD) and their association with risk factors for CD in a genetic risk birth cohort. Children from 6 clinical centers in 4 countries positive for HLA-DR3-DQ2 or DR4-DQ8 were annually screened for tissue transglutaminase antibodies (tTGA) and assessed for symptoms by questionnaires. Associations of symptoms with anthropometrics, known risk factors for CD, tTGA levels, and mucosal lesions in those biopsied were examined. Of 6706 screened children, 914 developed persistent positive tTGA, 406 underwent biopsies, and 340 had CD. Compared with age-matched tTGA-negative children, those with persistent tTGA were more likely to have symptoms at 2 (34% vs 19%, P < .001) and 3 years of age (28% vs 19%, P = .009) but not at 4 years (27% vs 21%, NS). Z-scores for height, weight, and BMI did not differ between groups. In children with persistent tTGA, having ≥ 1 symptom was associated with family history of CD (odds ratio = 2.59, 95% confidence interval, 1.21-5.57) but not with age, gender, or HLA-DR3-DQ2 homozygosity. At seroconversion, tTGA levels were higher in symptomatic than asymptomatic children (P < .001), in those from CD families (P < .001), and in US participants (P < .001) but not associated with age, gender, or HLA genotype. tTGA levels correlated with severity of mucosal lesions both in symptomatic (r = 0.53, P < .001) and asymptomatic children (r = 0.22, P = .01). A majority of children detected with persistent tTGA in screenings are asymptomatic and have normal growth by age 4 years. tTGA levels correlate more strongly with severity of mucosal lesions in symptomatic as compared with asymptomatic children. Copyright © 2015 by the American Academy of Pediatrics.

Scalable Robust Principal Component Analysis Using Grassmann Averages.

PubMed

Hauberg, Sren; Feragen, Aasa; Enficiaud, Raffi; Black, Michael J

2016-11-01

In large datasets, manual data verification is impossible, and we must expect the number of outliers to increase with data size. While principal component analysis (PCA) can reduce data size, and scalable solutions exist, it is well-known that outliers can arbitrarily corrupt the results. Unfortunately, state-of-the-art approaches for robust PCA are not scalable. We note that in a zero-mean dataset, each observation spans a one-dimensional subspace, giving a point on the Grassmann manifold. We show that the average subspace corresponds to the leading principal component for Gaussian data. We provide a simple algorithm for computing this Grassmann Average ( GA), and show that the subspace estimate is less sensitive to outliers than PCA for general distributions. Because averages can be efficiently computed, we immediately gain scalability. We exploit robust averaging to formulate the Robust Grassmann Average (RGA) as a form of robust PCA. The resulting Trimmed Grassmann Average ( TGA) is appropriate for computer vision because it is robust to pixel outliers. The algorithm has linear computational complexity and minimal memory requirements. We demonstrate TGA for background modeling, video restoration, and shadow removal. We show scalability by performing robust PCA on the entire Star Wars IV movie; a task beyond any current method. Source code is available online.

Glycyrrhetinic acid-modified TPGS polymeric micelles for hepatocellular carcinoma-targeted therapy.

PubMed

Zhu, Xiumei; Tsend-Ayush, Altansukh; Yuan, Zhongyue; Wen, Jing; Cai, Jiaxin; Luo, Shifu; Yao, Jianxu; Bian, Junxing; Yin, Linfang; Zhou, Jianping; Yao, Jing

2017-08-30

In this study, glycyrrhetinic acid (GA)-modified D-α-tocopheryl polyethylene glycol 1000 succinate (TPGS) polymeric micelles (TGA PMs) were developed for the delivery of etoposide (ETO) to hepatoma cells. GA was incorporated as a ligand because of its high affinity to the hepatocytes, while TPGS functioned as a P-gp inhibitor to reverse multidrug resistance. ETO-loaded TGA PMs (ETO-TGA PMs) displayed a mean particle size of 133.6±1.2nm with a low poly-dispersity index (0.224±0.013) and negative zeta potential (-16.30mV). The drug loading and entrapment efficiency of ETO-TGA PMs were 10.4% and 79.8%, respectively. ETO-TGA PMs also exhibited faster drug release behavior at pH 5.8 and relatively stable drug release at pH 7.4. Confocal laser scanning microscope (CLSM) observations and in vivo imaging studies revealed that TGA PMs displayed higher cellular uptake and selective accumulation at the tumor site, indicating good tumor targetability. Furthermore, ETO-TGA PMs displayed significant cytotoxicity towards HepG2 cells and higher anti-tumor efficacy (75.96%), compared to the control group. This could be due to TGA-mediated targeted drug delivery to the hepatocytes as well as P-gp inhibition. These findings suggest that TGA PMs have the potential to be used as a targeted drug delivery system for hepatic cancer therapy. Copyright © 2017 Elsevier B.V. All rights reserved.

Experimental oxygen potentials of U 1-yPr yO 2± x and thermodynamic assessment of the U-Pr-O system

DOE PAGES

McMurray, Jake W.; Silva, Chinthaka M.

2015-12-09

Thermogravimetric analysis (TGA) was used to determine the oxygen potentials of fluorite urania-praseodymia (U 1-yPr yO 2± x) solid solutions for y = 0.10 and 0.20 between 1000 and 1500 °C. A thermodynamic assessment of U-Pr-O system was performed using the CALPHAD (CALculation of PHAse Diagrams) method. Furthermore, the models well reproduce the TGA measurements and the computed phase relations are in good agreement with those proposed from an X-ray diffraction investigation.

X-ray diffraction and TGA kinetic analyses for chemical looping combustion applications.

PubMed

Tijani, Mansour Mohammedramadan; Aqsha, Aqsha; Mahinpey, Nader

2018-04-01

Synthesis and characterization of supported metal-based oxygen carriers were carried out to provide information related to the use of oxygen carriers for chemical looping combustion processes. The Cu, Co, Fe, Ni metals supported with Al 2 O 3 , CeO 2 , TiO 2 , ZrO 2 were prepared using the wetness impregnation technique. Then, the X-ray Diffraction (XRD) characterization of oxidized and reduced samples was obtained and presented. The kinetic analysis using Thermogravimetric analyzer (TGA) of the synthesized samples was conducted. The kinetics of reduction reaction of all samples were estimated and explained.

Chain length effect on the structure and stability of antimicrobial peptides of the (RW)n series.

PubMed

Phambu, Nsoki; Almarwani, Bashiyar; Garcia, Arlette M; Hamza, Nafisa S; Muhsen, Amira; Baidoo, Jacqueline E; Sunda-Meya, Anderson

2017-08-01

Three peptides containing (RW) n -NH 2 units (where n=4, 6, and 8) have been chosen to study the effect of the chain length on the structure and stability of the peptide using Fourier transform infrared (FTIR), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC) techniques. Their interactions with Escherichia coli (E. coli) membrane mimetic vesicles are discussed. Infrared results indicate that addition of (RW) n -NH 2 units increases intermolecular H bonds with antiparallel orientation. TGA and DSC results reveal that (RW) 6 -NH 2 shows the optimal chain length in terms of stability and all three peptides show a preferential interaction with one of the anionic lipids in E. coli membranes. SEM images of (RW) 4 -NH 2 present large aggregates while those of (RW) 6 -NH 2 and (RW) 8 -NH 2 present layers of sheet-like structure. In the presence of model membranes, (RW) n -NH 2 show fibrillar peptide superstructures. This study suggests that repeating structures of (RW) n -NH 2 promotes lateral assembly. Copyright © 2017 Elsevier B.V. All rights reserved.

Modification of carbon fiber surfaces via grafting with Meldrum's acid

NASA Astrophysics Data System (ADS)

Cuiqin, Fang; Jinxian, Wu; Julin, Wang; Tao, Zhang

2015-11-01

The mechanism of Meldrum's acid modifying carbon fiber surfaces was investigated in this work. The existing carbonyl groups of carbon fibers were grafted with Meldrum's acid to create carboxylic functionalized surfaces. The surface functionalization effect was detected with X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM), atomic force microscopy (AFM), and thermogravimetric analysis (TGA). The XPS results showed that the relative content of carboxylic groups on carbon fiber surfaces was increased from initial 1.41% to 7.84%, however, that of carbonyl groups was decreased from 23.11% to 13.28% after grafting reaction. The SEM, AFM and TGA results indicated that the surfaces of carbon fibers neither etched nor generated coating. The tensile strength of carbon fibers was preserved after grafting reaction according to single fiber tensile strength tests. The fibers were well combined with matrix and the maximal interlaminar shear strength (ILSS) of carbon fiber/epoxy resin composites was sharply increased approximately 74% after functionalization. The effects of acetic acid and sonication on the degree of the surface functionalization were also studied.

Comparison of In Situ Polymerization and Solution-Dispersion Techniques in the Preparation of Polyimide/Montmorillonite (MMT) Nanocomposites

PubMed Central

Ahmad, Mansor Bin; Gharayebi, Yadollah; Salit, Mohd. Sapuan; Hussein, Mohd. Zobir; Shameli, Kamyar

2011-01-01

In this paper, Polyimide/Montmorillonite Nanocomposites (PI/MMT NCs), based on aromatic diamine (4-Aminophenyl sulfone) (APS) and aromatic dianhydride (3,3′,4,4′-benzophenonetetracarboxylic dianhydride) (BTDA) were prepared using in situ polymerization and solution-dispersion techniques. The prepared PI/MMT NCs films were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM) and thermogravimetric analysis (TGA). The XRD results showed that at the content of 1.0 wt % Organo Montmorillonite (OMMT) for two techniques and 3.0 wt % OMMT for the in situ polymerization technique, the OMMT was well-intercalated, exfoliated and dispersed into polyimide matrix. The OMMT agglomerated when its amount exceeded 10 wt % and 3.0 wt % for solution-dispersion and in situ polymerization techniques respectively. These results were confirmed by the TEM images of the prepared PI/MMT NCs. The TGA thermograms indicated that thermal stability of prepared PI/MMT NCs were increased with the increase of loading that, the effect is higher for the samples prepared by in situ polymerization technique. PMID:22016643

Comparison of in situ polymerization and solution-dispersion techniques in the preparation of Polyimide/Montmorillonite (MMT) Nanocomposites.

PubMed

Ahmad, Mansor Bin; Gharayebi, Yadollah; Salit, Mohd Sapuan; Hussein, Mohd Zobir; Shameli, Kamyar

2011-01-01

In this paper, Polyimide/Montmorillonite Nanocomposites (PI/MMT NCs), based on aromatic diamine (4-Aminophenyl sulfone) (APS) and aromatic dianhydride (3,3',4,4'-benzophenonetetracarboxylic dianhydride) (BTDA) were prepared using in situ polymerization and solution-dispersion techniques. The prepared PI/MMT NCs films were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM) and thermogravimetric analysis (TGA). The XRD results showed that at the content of 1.0 wt % Organo Montmorillonite (OMMT) for two techniques and 3.0 wt % OMMT for the in situ polymerization technique, the OMMT was well-intercalated, exfoliated and dispersed into polyimide matrix. The OMMT agglomerated when its amount exceeded 10 wt % and 3.0 wt % for solution-dispersion and in situ polymerization techniques respectively. These results were confirmed by the TEM images of the prepared PI/MMT NCs. The TGA thermograms indicated that thermal stability of prepared PI/MMT NCs were increased with the increase of loading that, the effect is higher for the samples prepared by in situ polymerization technique.

Characteristics and kinetics study of simultaneous pyrolysis of microalgae Chlorella vulgaris, wood and polypropylene through TGA.

PubMed

Azizi, Kolsoom; Keshavarz Moraveji, Mostafa; Abedini Najafabadi, Hamed

2017-11-01

Thermal decomposition behavior and kinetics of microalgae Chlorella vulgaris, wood and polypropylene were investigated using thermogravimetric analysis (TGA). Experiments were carried out at heating rates of 10, 20 and 40°C/min from ambient temperature to 600°C. The results show that pyrolysis process of C. vulgaris and wood can be divided into three stages while pyrolysis of polypropylene occurs almost totally in one step. It is shown that wood can delay the pyrolysis of microalgae while microalgae can accelerate the pyrolysis of wood. The existence of polymer during the pyrolysis of microalgae or wood will lead to two divided groups of peaks in DTG curve of mixtures. The results showed that interaction is inhibitive rather than synergistic during the decomposition process of materials. Kinetics of process is studied by the Kissinger-Akahira-Sunose (KAS) and Flynn-Wall-Ozawa (FWO). The average E values obtained from FWO and KAS methods were 131.228 and 142.678kJ/mol, respectively. Copyright © 2017 Elsevier Ltd. All rights reserved.

Identifying Hydrated Salts Using Simultaneous Thermogravimetric Analysis and Differential Scanning Calorimetry

ERIC Educational Resources Information Center

Harris, Jerry D.; Rusch, Aaron W.

2013-01-01

simultaneous thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) to characterize colorless, hydrated salts with anhydrous melting points less than 1100 degrees C. The experiment could be used to supplement the lecture discussing gravimetric techniques. It is…

Relationship between habitual exercise and performance on cardio-pulmonary exercise testing differs between children with single and bi-ventricular circulation

PubMed Central

O'Byrne, Michael L; Desai, Sanyukta; Lane, Megan; McBride, Michael; Paridon, Stephen; Goldmuntz, Elizabeth

2016-01-01

Background Increasing habitual exercise has been associated with improved cardiopulmonary exercise testing (CPET) performance, specifically maximal oxygen consumption in children with operatively corrected congenital heart disease. This has not been studied in children following Fontan palliation, a population in whom CPET performance is dramatically diminished. Methods A single-center cross-sectional study with prospective and retrospective data collection was performed that assessed habitual exercise preceding a clinically indicated CPET in children and adolescents with Fontan palliation, transposition of the great arteries following arterial switch operation (TGA), and normal cardiac anatomy without prior operation. Data from contemporaneous clinical reports and imaging studies were collected. The association between percent predicted VO2max and habitual exercise duration adjusted for known covariates was tested. Results A total of 175 subjects (75 post Fontan, 20 with TGA, and 80 with normal cardiac anatomy) were enrolled. VO2max was lower in the Fontan group than patients with normal cardiac anatomy (p<0.0001) or TGA (p<0.0001). In Fontan subjects, both univariate and multivariate analysis failed to demonstrate a significant association between habitual exercise and VO2max (p=0.6), in sharp contrast to cardiac normal subjects. In multivariate analysis, increasing age was the only independent risk factor associated with decreasing VO2max in the Fontan group (p=0.003). Discussion Habitual exercise was not associated with VO2max in subjects with a Fontan as compared to biventricular circulation. Further research is necessary to understand why their habitual exercise is ineffective and/or what aspects of the Fontan circulation disrupt this association. PMID:27878634

Executive Function and Theory of Mind in School-Aged Children after Neonatal Corrective Cardiac Surgery for Transposition of the Great Arteries

ERIC Educational Resources Information Center

Calderon, Johanna; Bonnet, Damien; Courtin, Cyril; Concordet, Susan; Plumet, Marie-Helene; Angeard, Nathalie

2010-01-01

Aim: Cardiac malformations resulting in cyanosis, such as transposition of the great arteries (TGA), have been associated with neurodevelopmental dysfunction. The purpose of this study was to assess, for the first time, theory of mind (ToM), which is a key component of social cognition and executive functions in school-aged children with TGA.…

Kinetic study of solid waste pyrolysis using distributed activation energy model.

PubMed

Bhavanam, Anjireddy; Sastry, R C

2015-02-01

The pyrolysis characteristics of municipal solid waste, agricultural residues such as ground nut shell, cotton husk and their blends are investigated using non-isothermal thermogravimetric analysis (TGA) with in a temperature range of 30-900 °C at different heating rates of 10 °C, 30 °C and 50 °C/min in inert atmosphere. From the thermograms obtained from TGA, it is observed that the maximum rate of degradation occurred in the second stage of the pyrolysis process for all the solid wastes. The distributed activation energy model (DAEM) is used to study the pyrolysis kinetics of the solid wastes. The kinetic parameters E (activation energy), k0 (frequency factor) are calculated from this model. It is found that the range of activation energies for agricultural residues are lower than the municipal solid waste. The activation energies for the municipal solid waste pyrolysis process drastically decreased with addition of agricultural residues. The proposed DAEM is successfully validated with TGA experimental data. Copyright © 2014 Elsevier Ltd. All rights reserved.

Thermal Degradation Studies of Polyurethane/POSS Nanohybrid Elastomers

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

Lewicki, J P; Pielichowski, K; TremblotDeLaCroix, P

2010-03-05

Reported here is the synthesis of a series of Polyurethane/POSS nanohybrid elastomers, the characterization of their thermal stability and degradation behavior at elevated temperatures using a combination of Thermal Gravimetric Analysis (TGA) and Thermal Volatilization Analysis (TVA). A series of PU elastomers systems have been formulated incorporating varying levels of 1,2-propanediol-heptaisobutyl-POSS (PHIPOSS) as a chain extender unit, replacing butane diol. The bulk thermal stability of the nanohybrid systems has been characterized using TGA. Results indicate that covalent incorporation of POSS into the PU elastomer network increase the non-oxidative thermal stability of the systems. TVA analysis of the thermal degradation ofmore » the POSS/PU hybrid elastomers have demonstrated that the hybrid systems are indeed more thermally stable when compared to the unmodified PU matrix; evolving significantly reduced levels of volatile degradation products and exhibiting a {approx}30 C increase in onset degradation temperature. Furthermore, characterization of the distribution of degradation products from both unmodified and hybrid systems indicate that the inclusion of POSS in the PU network is directly influencing the degradation pathways of both the soft and hard block components of the elastomers: The POSS/PU hybrid systems show reduced levels of CO, CO2, water and increased levels of THF as products of thermal degradation.« less

Proximate Analysis of Coal

ERIC Educational Resources Information Center

Donahue, Craig J.; Rais, Elizabeth A.

2009-01-01

This lab experiment illustrates the use of thermogravimetric analysis (TGA) to perform proximate analysis on a series of coal samples of different rank. Peat and coke are also examined. A total of four exercises are described. These are dry exercises as students interpret previously recorded scans. The weight percent moisture, volatile matter,…

Chemical phase analysis of seed mediated synthesized anisotropic silver nanoparticles

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

Bharti, Amardeep, E-mail: abharti@pu.ac.in; Goyal, Navdeep; Singh, Suman

Noble-metal nanoparticles are of great interest because of its broad applications almost in every stream (i.e. biology, chemistry and engineering) due to their unique size/shape dependant properties. In this paper, chemical phase of seed mediated synthesized anisotropic silver nanoparticle (AgNPs) has been investigated via fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA). These nanaoparticles were synthesized by seed-growth method controlled by urea and dextrose results to highly stable 12-20 nm particle size revealed by zeta potential and transmission electron microscopy (TEM)

Near-infrared-emitting colloidal Ag2S quantum dots exhibiting upconversion luminescence

NASA Astrophysics Data System (ADS)

Zhang, Yanyan; Jiang, Danyu; Yang, Wei; Wang, Dandan; Zheng, Huiping; Du, Yuansheng; Li, Xi; Li, Qiang

2017-02-01

Ag2S quantum dots (QDs) coated with thioglycolic acid (Ag2S QDs-TGA) have been synthesized in an organic solvent via a stepwise addition of reagents. When excited by a 980 nm laser, the near-infrared-emitting colloidal Ag2S QDs-TGA exhibit upconversion luminescence (UCL). The observed photoluminescence (PL) was attributed to the presence of ligand-modified Ag2S on the QD surfaces. Hence, upon dilution of the solution, the PL intensity initially increased before subsequently decreasing, accompanied by a blue shift in the PL spectra. The PL phenomena can be attributed to the increase in the amount of ligand-modified Ag2S on the QD surfaces upon dilution, which in turn affected the fluorescence resonance energy transfer (FRET) and re-emission of the surface energy level. The relations between the emission intensity of Ag2S QDs-TGA and the excitation power are investigated, and the results confirm that the UCL in Ag2S QDs-TGA can be ascribed to a two-photon-assisted absorption process via a real energy state.

Preparation and characteristics of epoxy/clay/B4C nanocomposite at high concentration of boron carbide for neutron shielding application

NASA Astrophysics Data System (ADS)

Kiani, Mohammad Amin; Ahmadi, Seyed Javad; Outokesh, Mohammad; Adeli, Ruhollah; Mohammadi, Aghil

2017-12-01

In this research, the characteristics of the prepared samples in epoxy matrix by means of X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS), as well as scanning electron microscope (SEM) are evaluated. Meanwhile, the obtained mechanical properties of the specimen are investigated. Thermogravimetric analysis (TGA) is also employed to evaluate the thermal degradation of manufactured nanocomposites. The thermal neutron absorption properties of nanocomposites containing 3 wt% of montmorillonite nanoclay (closite30B) have been studied experimentally, using an Am-Be point source. Mechanical tests reveal that the higher B4C concentrations, the more tensile strengths, but lower Young's modulus in all samples under consideration. TGA analysis also shows that thermal stability of the nanocomposite, increases in presence of B4C. Finally, neutron absorption analysis shows that increasing the B4C concentration leads to a nonlinearly build-up of neutron absorption cross section.

Preparation of SS316L MIM feedstock with biopolymer as a binder

NASA Astrophysics Data System (ADS)

Abdullah, A. A.; Norita, H.; Azlina, H. N.; Sulong, A. B.; Mas'ood, N. N.

2018-01-01

This paper focus on feedstock preparation for SS316L metal injection molding (MIM) part. The primary step of feedstock preparation, critical powder loading determined by two method; maximum filled volume calculation model and torque analysis. The critical powder loading determined by calculation was 70 vol% to 77 vol% while for experimental approaches shows the value of 75 vol%. The feedstock was prepared by mixing SS316L powder and polymer binder with ratio 70:30 at 175 °C with speed of 50 rpm. The feedstock was analyzed by thermogravimetric analysis (TGA) and Scanning electron microscope (SEM). The composition for the feedstock after preparation step was confirmed by TGA. It was found that the prepared feedstock component was compatible to each other and composition is maintain along the mixing step.

Preparation of thermally stable nanocrystalline hydroxyapatite by hydrothermal method.

PubMed

Prakash Parthiban, S; Elayaraja, K; Girija, E K; Yokogawa, Y; Kesavamoorthy, R; Palanichamy, M; Asokan, K; Narayana Kalkura, S

2009-12-01

Thermally stable hydroxyapatite (HAp) was synthesized by hydrothermal method in the presence of malic acid. X-ray diffraction (XRD), Fourier transform infra-red spectroscopy (FT-IR), Raman spectroscopy, scanning electron microscopy (SEM), differential thermal analysis (DTA), thermogravimetric analysis (TGA) was done on the synthesized powders. These analyses confirmed the sample to be free from impurities and other phases of calcium phosphates, and were of rhombus morphology along with nanosized particles. IR and Raman analyses indicated the adsorption of malic acid on HAp. Thermal stability of the synthesized HAp was confirmed by DTA and TGA. The synthesized powders were thermally stable upto 1,400 degrees C and showed no phase change. The proposed method might be useful for producing thermally stable HAp which is a necessity for high temperature coating applications.

An investigation of co-combustion municipal sewage sludge with biomass in a 20kW BFB combustor under air-fired and oxygen-enriched condition.

PubMed

Kumar, Rajesh; Singh, Ravi Inder

2017-12-01

The behavior of municipal sewage sludge (MSS) with biomass (Guar stalks (GS), Mustard Husk (MH), Prosopis Juliflora Wood (PJW)) has been investigated in a 20kW bubbling fluidized bed (BFB) combustor under both air-fired (A-F) and oxygen-enriched (O-E) conditions. The work presented is divided into three parts, first part cover the thermogravimetric analysis (TGA), second part cover the experimental investigation of BFB combustor, and third part covers the ash analysis. TGA was performed with a ratio of 50%MSS/50%biomass (GS, MH, PJW) and results show that 50%MSS/50%GS has highest combustion characteristic factor (CCF). The experimental investigation of BFB combustor was performed for two different ratios of MSS/biomass (50%/50% and 25%/75%) and the combustion characteristics of blends were distinctive under both A-F and O-E condition. Despite 50%MSS/50%GS showing the highest combustion performance in TGA analysis, it formed agglomerates during burning in BFB. Due to this formation of large amount of agglomerates, de-fluidization was observed in the combustor bed after 65-75min in A-F conditions. The rate of de-fluidization increased under O-E condition. The de-fluidization problem disappeared when the share of MSS was reduced to 25%, but small amounts of the agglomerate were still present in the bed. With oxygen enhancement, the combustion efficiency of BFB combustor was improved and flue gasses were found within permissible limit. The maximum conceivable combustion efficiency (97.1%) for BFB combustor was accomplished by using 50% MSS/50%PJW under O-E condition. Results show that a ratio of 25%MSS/75%biomass combusted successfully inside the BFB combustor and extensive work is required for efficient utilization of significant share of MSS with biomass. SEM/EDS analyses were performed for agglomerate produced and for the damaged heater to study the surface morphology and compositions. The elemental heterogeneity of fly ash generated during MSS/biomass combustion was analyzed using Microwave Plasma-Atomic Emission Spectroscopy (MP-AES). Copyright © 2017 Elsevier Ltd. All rights reserved.

Assessment of Tree Leaves Flakes Mixed with Crude Glycerol as a Bioenergy Source

PubMed Central

Hilal-AlNaqbi, Ali; Al-Omari, Salah B.; Selim, Mohamed Y. E.

2016-01-01

The gasification and combustion of dry tree leaves and the cogasification of dry tree leaves soaking crude glycerol were studied experimentally. An updraft fixed bed gasification and combustion system was built. The operation was conducted at different air to fuel ratios. Results show more stable combustion and more effective heat transfer to furnace walls for the cases when tree leaves flakes are mixed with 20 percent (on mass basis) of crude glycerol, as compared with the case when only dry tree leaves are used as fuel. TGA analysis was also conducted for the two fuels used under both air and nitrogen environments. For the crude glycerol, four phases of pyrolysis and gasification were noticed under either of the two surrounding gaseous media (air or nitrogen). For the dry tree leaves, the pyrolysis under nitrogen shows only a simple smooth pyrolysis and gasification curve without showing the different distinct phases that were otherwise identified when the pyrolysis is conducted under air environment. Moreover, the air TGA results lead to more gasification due to the char oxidation at high temperatures. DTG results are also presented and discussed. PMID:27413749

Flame-retardant polyvinyl alcohol membrane with high transparency based on a reactive phosphorus-containing compound

NASA Astrophysics Data System (ADS)

Peng, Sha; Zhou, Ming; Liu, Feiyan; Zhang, Chang; Liu, Xueqing; Liu, Jiyan; Zou, Liyong; Chen, Jia

2017-08-01

Flame-retardant polyvinyl alcohol (PVA) membranes with high transparency and flexibility were prepared by mixing an aqueous solution of a phosphorus-containing acrylic acid (AOPA) with PVA. The reaction between AOPA and PVA, the transparency, the crystallinity and the flexibility of the membrane were investigated with Fourier transform infrared spectrometry (FTIR), UV-vis light transmittance, X-ray diffraction and tensile tests, respectively. The limited oxygen index (LOI) and vertical flame (UL 94 VTM), microscale combustion calorimetry, thermogravimetric analysis (TGA) and TGA-FTIR were employed to evaluate the flame retardancy as well as to reveal the corresponding mechanisms. Results showed that PVA containing 30 wt% of AOPA can reach the UL 94 VTM V0 rating with an LOI of 27.3% and retain 95% of the original transparency of pure PVA. Adding AOPA reduces crystallinity of PVA, while the flexibility is increased. AOPA depresses the thermal degradation of PVA and promotes char formation during combustion. The proposed decomposition mechanism indicates that AOPA acts mainly in the condensed phase.

Synergistic effect between ammonium polyphosphate and expandable graphite on flame-retarded poly(butylene terephthalate)

NASA Astrophysics Data System (ADS)

Zhang, Weizhou; Ren, Jiawei; Wei, Ting; Guo, Weihong

2018-02-01

In this paper, the synergistic effect of ammonium polyphosphate (APP) and expandable graphite (EG) on flame-retarded poly(butylene terephthalate) (PBT) was systermically investigated using limiting oxygen index (LOI), UL-94 testing, microscale combustion calorimetry (MCC), thermal-gravimetric analysis (TGA) and scanning electronic microscopy (SEM). PBT composites containing 20 wt% of APP: EG (1:3) combinations exhibits a high LOI value of 29.8 and reaches V-0 rating in UL-94 testing, indicating that the flame retardant property is greatly enhanced compared to the composites solely with APP or EG. SEM images show that the combination of APP and EG could promote the formation of a compact char layer. The compact char layer protects the PBT resin efficiently by preventing penetration of heat flux inside the matrix and retards the decomposition of PBT, consequently improves the thermal stability of PBT materials as revealed by TGA. All of the results demonstrate that APP and EG are high efficiency synergists for improving the flame retardation of PBT materials.

Studying the effects of laccase treatment in a softwood dissolving pulp: cellulose reactivity and crystallinity.

PubMed

Quintana, Elisabet; Valls, Cristina; Barneto, Agustín G; Vidal, Teresa; Ariza, José; Roncero, M Blanca

2015-03-30

An enzymatic biobleaching sequence (LVAQPO) using a laccase from Trametes villosa in combination with violuric acid (VA) and then followed by a pressurized hydrogen peroxide treatment (PO) was developed and found to give high bleaching properties and meet dissolving pulp requirements: high brightness, low content of hemicellulose, satisfactory pulp reactivity, no significant cellulose degradation manifested by α-cellulose and HPLC, and brightness stability against moist heat ageing. The incorporation of a laccase-mediator system (LMS) to bleach sulphite pulps can be a good alternative to traditional bleaching processes since thermogravimetric analysis (TGA) showed that the laccase treatment prevented the adverse effect of hydrogen peroxide on fibre surface as observed during a conventional hydrogen peroxide bleaching treatment (PO). Although VA exhibited the best results in terms of bleaching properties, the performance of natural mediators, such as p-coumaric acid and syringaldehyde, was discussed in relation to changes in cellulose surface detected by TGA. Copyright © 2014 Elsevier Ltd. All rights reserved.

Effects of alkali treatment on the mechanical and thermal properties of Sansevieria trifasciata fiber

NASA Astrophysics Data System (ADS)

Mardiyati, Steven, Rizkiansyah, Raden Reza; Senoaji, A.; Suratman, R.

2016-04-01

In this study, Sansevieria trifasciata fibers were treated by NaOH with concentration 1%,3%, and 5wt% at 100°C for 2 hours. Chesson-Datta methods was used to determine the lignocellulose content of raw sansevieria fibers and to investigate effect of alkali treatment on lignin content of the fiber. Mechanical properties and thermal properties of treated and untreated fibers were measured by means of tensile testing machine and thermogravimetric analysis (TGA).The cellulose and lignin contents of raw sansevieria fiber obtained from Chesson-Datta method were 56% and 6% respectively. Mechanical testing of fibers showed the increase of tensile strength from 647 MPa for raw fibers to 902 MPa for 5wt% NaOH treated fibers. TGA result showed the alkali treatment increase the thermal resistance of fibers from 288°C for raw fibers to 307°C for 5% NaOH treated fiber. It was found that alkali treatment affect the mechanical properties and thermal properties of sansevieria fibers.

Degradation Behaviour of Gamma Irradiated Poly(Acrylic Acid)-graft-Chitosan Superabsorbent Hydrogel

NASA Astrophysics Data System (ADS)

Ria Barleany, Dhena; Ilhami, Alpin; Yusuf Yudanto, Dea; Erizal

2018-03-01

A series of superabsorbent hydrogels were prepared from chitosan and partially neutralized acrylic acid at room temperature by gamma irradiation technique. The effect of irradiation and chitosan addition to the degradation behaviour of polymer were investigated. The gel content, swelling capacity, Equillibrium Degree of Swelling (EDS), Fourier Transform Infra Red (FTIR), and Scanning Electron Microscopy (SEM) study were also performed. Natural degradation in soil and thermal degradation by using of TGA analysis were observed. The variation of chitosan compositions were 0.5, 1, 1.5, and 2 g and the total irradiation doses were 5, 10, 15, and 20 kGy. The highest water capacity of 583.3 g water/g dry hydrogel was resulted from 5 kGy total irradiation dose and 0,5 g addition of chitosan. From the thermal degradation evaluation by using of TGA analysis showed that irradiation dose did not give a significant influence to the degradation rate. The rate of thermal degradation was ranged between 2.42 to 2.55 mg/min. In the natural test of degradation behaviour by using of soil medium, the hydrogel product with chitosan addition was found to have better degradability compared with the poly(acrylic acid) polymer without chitosan.

Thermal behavior of gamma-irradiated low-density polyethylene/paraffin wax blend

NASA Astrophysics Data System (ADS)

Abdou, Saleh M.; Elnahas, H. H.; El-Zahed, H.; Abdeldaym, A.

2016-05-01

The thermal properties of low-density polyethylene (LDPE)/paraffin wax blends were studied using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and melt flow index (MFI). Blends of LDPE/wax in ratios of 100/0, 98/2, 96/4, 94/6, 92/8, 90/10 and 85/15 (w/w) were prepared by melt-mixing at the temperature of 150°C. It was found that increasing the wax content more than 15% leads to phase separation. DSC results showed that for all blends both the melting temperature (Tm) and the melting enthalpy (ΔHm) decrease linearly with an increase in wax content. TGA analysis showed that the thermal stability of all blends decreases linearly with increasing wax content. No clear correlation was observed between the melting point and thermal stability. Horowitz and Metzger method was used to determine the thermal activation energy (Ea). MFI increased exponentially by increasing the wax content. The effect of gamma irradiation on the thermal behavior of the blends was also investigated at different gamma irradiation doses. Significant correlations were found between the thermal parameters (Tm, ΔHm, T5%, Ea and MFI) and the amount of wax content and gamma irradiation.

Analysis of polyethylene microplastics in environmental samples, using a thermal decomposition method.

PubMed

Dümichen, Erik; Barthel, Anne-Kathrin; Braun, Ulrike; Bannick, Claus G; Brand, Kathrin; Jekel, Martin; Senz, Rainer

2015-11-15

Small polymer particles with a diameter of less than 5 mm called microplastics find their way into the environment from polymer debris and industrial production. Therefore a method is needed to identify and quantify microplastics in various environmental samples to generate reliable concentration values. Such concentration values, i.e. quantitative results, are necessary for an assessment of microplastic in environmental media. This was achieved by thermal extraction in thermogravimetric analysis (TGA), connected to a solid-phase adsorber. These adsorbers were subsequently analysed by thermal desorption gas chromatography mass spectrometry (TDS-GC-MS). In comparison to other chromatographic methods, like pyrolyse gas chromatography mass spectrometry (Py-GC-MS), the relatively high sample masses in TGA (about 200 times higher than used in Py-GC-MS) analysed here enable the measurement of complex matrices that are not homogenous on a small scale. Through the characteristic decomposition products known for every kind of polymer it is possible to identify and even to quantify polymer particles in various matrices. Polyethylene (PE), one of the most important representatives for microplastics, was chosen as an example for identification and quantification. Copyright © 2015 Elsevier Ltd. All rights reserved.

Structure-properties relationships of novel poly(carbonate-co-amide) segmented copolymers with polyamide-6 as hard segments and polycarbonate as soft segments

NASA Astrophysics Data System (ADS)

Yang, Yunyun; Kong, Weibo; Yuan, Ye; Zhou, Changlin; Cai, Xufu

2018-04-01

Novel poly(carbonate-co-amide) (PCA) block copolymers are prepared with polycarbonate diol (PCD) as soft segments, polyamide-6 (PA6) as hard segments and 4,4'-diphenylmethane diisocyanate (MDI) as coupling agent through reactive processing. The reactive processing strategy is eco-friendly and resolve the incompatibility between polyamide segments and PCD segments in preparation processing. The chemical structure, crystalline properties, thermal properties, mechanical properties and water resistance were extensively studied by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Differential scanning calorimetry (DSC), Thermal gravity analysis (TGA), Dynamic mechanical analysis (DMA), tensile testing, water contact angle and water absorption, respectively. The as-prepared PCAs exhibit obvious microphase separation between the crystalline hard PA6 phase and amorphous PCD soft segments. Meanwhile, PCAs showed outstanding mechanical with the maximum tensile strength of 46.3 MPa and elongation at break of 909%. The contact angle and water absorption results indicate that PCAs demonstrate outstanding water resistance even though possess the hydrophilic surfaces. The TGA measurements prove that the thermal stability of PCA can satisfy the requirement of multiple-processing without decomposition.

The synthesis and luminescence of europium (III) complex based on deprotonated 1-(4-ethyl-4H-thieno[3,2-b]indol-6-yl)-4,4,4-trifluorobutane-1,3-dionate and 1,10-phenanthroline

NASA Astrophysics Data System (ADS)

Liu, Sheng-Gui; Su, Wen-Yi; Pan, Rong-Kai; Zhou, Xiao-Ping; Wen, Xin-Lan; Chen, Yi-Zhao; Wang, Sheng; Shi, Xiao-Bo

2013-02-01

A new β-diketone ligand, 1-(4-ethyl-4H-thieno[3,2-b]indol-6-yl)-4,4,4-trifluoro-butane-1,3-dione(HL) was synthesized by four steps reaction (Suzuki-Miyaura cross-coupling, Cadogan cyclization, N-ethylation and Claisen condensation reaction) from 1-(4-bromo-3-nitrophenyl)ethanone and thiophen-2-ylboronic acid. Deprotonated ligand (L-1) and 1,10-phenanthroline (phen) coordinated to Eu3+ to obtain a new europium (III) complex, EuL3(phen). The complex was characterized by elementary analysis, IR, 1H NMR, UV-Visible absorption spectroscopy, thermogravimetric analysis (TGA) and photoluminescence (PL) measurements in detail. TGA shows that the decomposition temperature of the complex is up to 320 °C. PL measurement results indicate that the Eu(III) complex exhibit intense red-emission with the characteristic of europium ion. Red LED device was successfully fabricated by employing the complex onto 380 nm-emitting InGaN chip, which shows that the complex can act as red phosphor in combination with 380 nm-emitting chips.

Alterations in mineral properties of zebrafish skeletal bone induced by liliput dtc232 gene mutation

NASA Astrophysics Data System (ADS)

Wang, Xiu-Mei; Cui, Fu-Zhai; Ge, Jun; Ma, Chen

2003-11-01

The alterations of mineral properties of bone by gene mutation in the zebrafish, which is associated with abnormal bone mineralization and bone diseases, were reported for the first time in this paper. Transmission electron microscope (TEM), Fourier transform infrared microspectroscopy (FTIRM) and thermogravimetric analysis (TGA) were used to investigate the changes in the mineral. Significant variations of the morphologies of the minerals and the mineral/matrix ratio after liliputdtc232(lil) gene mutation have been observed. The morphologies of the minerals, examined by TEM, revealed that the mutated mineral was in bigger size and the shape was block shaped but not plate shaped. The results of FTIRM indicated that the lil mutant zebrafish skeleton exhibited a greater mineral/matrix ratio (phosphate/matrix=4.86±0.28) than that of wild-type zebrafish bone (phosphate/matrix=4.17±0.67), which was confirmed by TGA analysis. Furthermore, the mineral of lil bone became less mature and crystalline with more ion substitutions. And the selected areas electron diffraction (SAED) patterns showed that the main crystal phases of the two type fishes were both hydroxyapatite. In addition, we have discussed the relationship among the mineral properties, nanomechanical properties and biomineralization process.

Assessment of Uncertainty in the Determination of Activation Energy for Polymeric Materials

NASA Technical Reports Server (NTRS)

Darby, Stephania P.; Landrum, D. Brian; Coleman, Hugh W.

1998-01-01

An assessment of the experimental uncertainty in obtaining the kinetic activation energy from thermogravimetric analysis (TGA) data is presented. A neat phenolic resin, Borden SC1O08, was heated at three heating rates to obtain weight loss vs temperature data. Activation energy was calculated by two methods: the traditional Flynn and Wall method based on the slope of log(q) versus 1/T, and a modification of this method where the ordinate and abscissa are reversed in the linear regression. The modified method produced a more accurate curve fit of the data, was more sensitive to data nonlinearity, and gave a value of activation energy 75 percent greater than the original method. An uncertainty analysis using the modified method yielded a 60 percent uncertainty in the average activation energy. Based on this result, the activation energy for a carbon-phenolic material was doubled and used to calculate the ablation rate In a typical solid rocket environment. Doubling the activation energy increased surface recession by 3 percent. Current TGA data reduction techniques that use the traditional Flynn and Wall approach to calculate activation energy should be changed to the modified method.

Sodium hydrogen carbonate as an alternative blowing agent in the preparation of palm-based polyurethane foam

NASA Astrophysics Data System (ADS)

Shakir, Amira Shakim Abdul; Badri, Khairiah Haji; Hua, Chia Chin

2016-11-01

An environmental-friendly blowing agent has been used to fabricate flexible polyurethane (PU) foam. Polyurethane foam was prepared from palm kernel oil-based monoester polyol (PKO-p) via prepolymerization method. Acetone has been used as solvent in this study. The developed polyurethane foam was characterized using tensile, differential scanning calorimetry analysis (DSC), thermogravimetric analysis (TGA), optical microscope and drop shape analyzer. The mechanical properties of the PU-reference (PU-R) and PU-NaHCO3 foam was analyzed by tensile using ASTM D 3574-01. From the results, the elongation of PU- NaHCO3 shows reduction to 26.3 % compared to PU-R. The DSC showed two glass transition temperatures in all samples that belonged to the PU-R and PU-NaHCO3. TGA revealed that the incorporation of sodium hydrogen carbonate into the PU system did not show significant difference as compared to the control PU. The morphology of both PU was investigated using optical microscope. Contact angle has been measured to determine the hydrophobicity of the PU. The PU- NaHCO3 exhibited an increase in contact angle (93.1°).

Al-Mn CVD-FBR coating on P92 steel as protection against steam oxidation at 650 °C: TGA-MS study

NASA Astrophysics Data System (ADS)

Castañeda, S. I.; Pérez, F. J.

2018-02-01

The initial stages oxidation of the P92 ferritic/martensitic steel with and without Al-Mn coating at 650 °C in Ar+40%H2O for 240 h were investigated by mass spectrometry (MS) and thermogravimetric analysis (TGA). TGA-MS measurements were conducted in a closed steam loop. An Al-Mn coating was deposited on P92 steel at 580 °C for 2 h by chemical vapour deposition in a fluidized bed reactor (CVD-FBR). The coating as-deposited was treated in the same reactor at 700 °C in Ar for 2h, in order to produce aluminide phases that form the protective alumina layer (Al2O3) during oxidation. MS measurements at 650 °C of the Al-Mn/P92 sample for 200 h indicated the presence of (Al-Mn-Cr-Fe-O) volatile species of small intensity. Uncoated P92 steel oxidized under the same steam oxidation conditions emitted greater intensities of volatile species of Cr, Fe and Mo in comparison with intensities from coated steel. TGA measurements verified that the mass gained by the coated sample was up to 300 times lower than for uncoated P92 steel. The morphology, composition and structure of samples by Scanning Electron Microscopy SEM, Backscattered Electron (BSE) detection, X-ray Energy Dispersive Spectrometry (EDAX) and X-ray Diffraction (XRD) are described.

Maternal-infant interaction and autonomic function in healthy infants and infants with transposition of the great arteries.

PubMed

Harrison, Tondi M; Ferree, Allison

2014-12-01

The quality of maternal-infant interaction is a critical factor in the development of infants' autonomic function and social engagement skills. In this secondary data analysis, relationships among infant and maternal affect and behavior and quality of dyadic interaction, as measured by the Parent-Child Early Relational Assessment, and infant autonomic function, as measured by heart rate variability, were examined during feeding at 2 weeks and 2 months of age in 16 healthy infants and in 15 infants with transposition of the great arteries (TGA). Contrary to previous research, at 2 weeks infant age, mothers of infants with TGA had significantly higher scores in affect and behavior than did mothers of healthy infants. The affect and behavior and quality of dyadic interaction of infants with TGA also did not differ from that of healthy infants. Although infants' social engagement skills did not differ by health condition (TGA or healthy), these skills did differ by parasympathetic nervous system function: infants better able to suppress vagal activity with challenge had more positive and less dysregulated affect and behavior, regardless of health status. These findings suggest that maternal-infant interactions for some cardiac disease subgroups may not differ from healthy dyads. Additional research is required to identify both healthy and ill infants with delayed autonomic maturation and to develop and test interventions to enhance critical interactive functions. © 2014 Wiley Periodicals, Inc.

Antigastric parietal cell and antithyroid autoantibodies in patients with recurrent aphthous stomatitis.

PubMed

Wu, Yang-Che; Wu, Yu-Hsueh; Wang, Yi-Ping; Chang, Julia Yu-Fong; Chen, Hsin-Ming; Sun, Andy

2017-01-01

Anti-gastric parietal cell antibody (GPCA), anti-thyroglobulin antibody (TGA), and anti-thyroid microsomal antibody (TMA) have not yet been reported in patients with recurrent aphthous stomatitis (RAS). This study mainly assessed the frequencies of the presence of serum GPCA, TGA, and TMA in different types of RAS patients. Serum GPCA, TGA, and TMA levels were measured in 355 RAS patients of different subtypes and in 355 age- and sex-matched healthy control individuals. We found that 13.0%, 19.4%, and 19.7% of 355 RAS patients, 16.7%, 23.3%, and 21.7% of 60 major-typed RAS patients, 12.2%, 18.6%, and 19.3% of 295 minor-typed RAS patients, 18.1%, 20.0%, and 21.9% of 160 atrophic glossitis-positive RAS (AG+/RAS) patients, and 8.7%, 19.0%, and 17.9% of 195 AG-negative RAS (AG-/RAS) patients had the presence of GPCA, TGA, and TMA in their sera, respectively. RAS, major-typed RAS, minor-typed RAS, AG+/RAS, and AG-/RAS patients all had a significantly higher frequency of GPCA, TGA, or TMA positivity than healthy control individuals (all p < 0.001). Of 65 TGA/TMA-positive RAS patients whose serum thyroid-stimulating hormone (TSH) levels were measured, 76.9%, 12.3%, and 10.8% of these TGA/TMA-positive RAS patients had normal, lower, and higher serum TSH levels, respectively. We conclude that approximately one-third RAS patients may have GPCA/TGA/TMA positivity in their sera. Because some GPCA-positive patients may develop pernicious anemia, autoimmune atrophic gastritis, and gastric carcinoma, and some TGA/TMA-positive patients may have thyroid dysfunction such as hyperthyroidism and hypothyroidism, these patients should be referred to doctors for further management. Copyright © 2016. Published by Elsevier B.V.

Performance of two commercial ELISAs for detecting IgA anti-human and anti-guinea pig tissue transglutaminase antibodies.

PubMed

Abrantes-Lemos, Clarice Pires; Nakhle, Maria Cristina; Damiao, Aderson Omar Mourao Cintra; Sipahi, Aytan Miranda; Carrilho, Flair José; Cancado, Eduardo Luiz R

2010-01-01

Sensitivity and specificity of anti-human tissue transglutaminase antibodies (anti-htTGA) seem to be superior to those of anti-tissue transglutaminase of guinea pig (anti-gptTGA) for screening patients with celiac disease (CD), but there are still controversies. The aim of this study was to evaluate the performance of two INOVA ELISA kits to detect IgA anti-htTGA and anti-gptTGA in patients with and without CD. The study groups were comprised of 49 anti-endomysial antibody (EMA)-positive untreated-CD, and 123 controls (EMA-negative treated CD, EMA-negative chronic diarrhea, autoimmune hepatitis, inflammatory bowel disease and healthy people). The agreement between the two ELISAs was statistically significant in all study groups and there was no significant difference between them (92.7% agreement; kappa = 0.70; kappa p = 0.001; McNemar p = 1). All patients with serum reactivity of more than 100 units had histologic diagnosis of CD. In seven of 10 patients with treated-CD who had control biopsies, villous atrophy was still present in four who tested positive by both kits. Two of three celiacs with histologic remission tested positive for both anti-tTGA. the anti-gptTGA and anti-htTGA determination were equally efficient in identifying patients with untreated-CD with high titers of EMA. Whatever the anti-tTGA ELISA used, the reactivity above 100 units was always related to active CD diagnosed by histologic alterations in intestinal biopsies. The anti-tTGA reactivity by both kits was not only similar in determining histologic activity in the follow-up of CD after a gluten free diet, but also in identifying positive sera from the control groups, regardless if CD has been confirmed by duodenal biopsies.

Post-irradiation hardness development, chemical softening, and thermal stability of bulk-fill and conventional resin-composites.

PubMed

Alshali, Ruwaida Z; Salim, Nesreen A; Satterthwaite, Julian D; Silikas, Nick

2015-02-01

To measure bottom/top hardness ratio of bulk-fill and conventional resin-composite materials, and to assess hardness changes after dry and ethanol storage. Filler content and kinetics of thermal decomposition were also tested using thermogravimetric analysis (TGA). Six bulk-fill (SureFil SDR, Venus bulk fill, X-tra base, Filtek bulk fill flowable, Sonic fill, and Tetric EvoCeram bulk-fill) and eight conventional resin-composite materials (Grandioso flow, Venus Diamond flow, X-flow, Filtek Supreme Ultra Flowable, Grandioso, Venus Diamond, TPH Spectrum, and Filtek Z250) were tested (n=5). Initial and 24h (post-cure dry storage) top and bottom microhardness values were measured. Microhardness was re-measured after the samples were stored in 75% ethanol/water solution. Thermal decomposition and filler content were assessed by TGA. Results were analysed using one-way ANOVA and paired sample t-test (α=0.05). All materials showed significant increase of microhardness after 24h of dry storage which ranged from 100.1% to 9.1%. Bottom/top microhardness ratio >0.9 was exhibited by all materials. All materials showed significant decrease of microhardness after 24h of storage in 75% ethanol/water which ranged from 14.5% to 74.2%. The extent of post-irradiation hardness development was positively correlated to the extent of ethanol softening (R(2)=0.89, p<0.001). Initial thermal decomposition temperature assessed by TGA was variable and was correlated to ethanol softening. Bulk-fill resin-composites exhibit comparable bottom/top hardness ratio to conventional materials at recommended manufacturer thickness. Hardness was affected to a variable extent by storage with variable inorganic filler content and initial thermal decomposition shown by TGA. The manufacturer recommended depth of cure of bulk-fill resin-composites can be reached based on the microhardness method. Characterization of the primary polymer network of a resin-composite material should be considered when evaluating its stability in the aqueous oral environment. Copyright © 2014 Elsevier Ltd. All rights reserved.

Generation of drugs coated iron nanoparticles through high energy ball milling

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

Radhika Devi, A.; Murty, B. S.; Chelvane, J. A.

The iron nanoparticles coated with oleic acid and drugs such as folic acid/Amoxicillin were synthesized by high energy ball milling and characterized by X-ray diffraction, Transmission electron microscope, zeta potential, dynamic light scattering, Fourier Transform Infra red (FT-IR) measurements, and thermo gravimetric analysis (TGA). FT-IR and TGA measurements show good adsorption of drugs on oleic acid coated nanoparticles. Magnetic measurements indicate that saturation magnetization is larger for amoxicillin coated particles compared to folic acid coated particles. The biocompatibility of the magnetic nanoparticles prepared was evaluated by in vitro cytotoxicity assay using L929 cells as model cells.

Room Temperature Magnetic Behavior In Nanocrystalline Ni-Doped Zro2 By Microwave-Assisted Polyol Synthesis

NASA Astrophysics Data System (ADS)

Parimita Rath, Pragyan; Parhi, Pankaj Kumar; Ranjan Panda, Sirish; Priyadarshini, Barsharani; Ranjan Sahoo, Tapas

2017-08-01

This article, deals with a microwave-assisted polyol method to demonstrate a low temperature route < 250°C, to prepare a high temperature cubic zirconia phase. Powder XRD pattern shows broad diffraction peaks suggesting nanometric size of the particles. Magnetic behavior of 1-5 at% Ni doped samples show a threshold for substitutional induced room temperature ferromagnetism up to 3 at% of Ni. TGA data reveals that Ni-doped ZrO2 polyol precursors decompose exothermically below 300°C. IR data confirms the reduction of Zr(OH)4 precipitates to ZrO2, in agreement with the conclusions drawn from the TGA analysis.

Thermal degradation and morphological studies on raw and reinforced polyacrylic rubbers

NASA Astrophysics Data System (ADS)

Sasikala, A.; Kala, A.

2017-05-01

Poly acrylate rubbers (ACM) of today are saturated copolymers of monomeric acrylic esters and reactive cure site monomers. ACM elastomer have also found use in vibration damping due to its excellent resilience. Other applications include textiles, adhesives, and coatings. Two state of Poly acrylic raw and reinforced Rubber are analyzed using FTIR spectroscopy, Optical Microscopy, DSC and TGA measurements. With the objective of determined the mechanical strength, Thermal analysis on TGA and DSC studies show that, the thermal degradation temperature Tg of the sample material is obtained and activation energy is also calaulated by Broido, Horowitz - Metzger, Piloyan-Novikova and Coats Redfern methods which are found.

A plasma arc reactor for fullerene research

NASA Astrophysics Data System (ADS)

Anderson, T. T.; Dyer, P. L.; Dykes, J. W.; Klavins, P.; Anderson, P. E.; Liu, J. Z.; Shelton, R. N.

1994-12-01

A modified Krätschmer-Huffman reactor for the mass production of fullerenes is presented. Fullerene mass production is fundamental for the synthesis of higher and endohedral fullerenes. The reactor employs mechanisms for continuous graphite-rod feeding and in situ slag removal. Soot collects into a Soxhlet extraction thimble which serves as a fore-line vacuum pump filter, thereby easing fullerene separation from soot. Thermal gravimetric analysis (TGA) for yield determination is reported. This TGA method is faster and uses smaller samples than Soxhlet extraction methods which rely on aromatic solvents. Production of 10 g of soot per hour is readily achieved utilizing this reactor. Fullerene yields of 20% are attained routinely.

Fabrication, characterization and gamma rays shielding properties of nano and micro lead oxide-dispersed-high density polyethylene composites

NASA Astrophysics Data System (ADS)

Mahmoud, Mohamed E.; El-Khatib, Ahmed M.; Badawi, Mohamed S.; Rashad, Amal R.; El-Sharkawy, Rehab M.; Thabet, Abouzeid A.

2018-04-01

Polymer composites of high-density polyethylene (HD-PE) filled with powdered lead oxide nanoparticles (PbO NPs) and bulk lead oxide (PbO Blk) were prepared with filler weight fraction [10% and 50%]. These polymer composites were investigated for radiation-shielding of gamma-rays emitted from radioactive point sources [241Am, 133Ba, 137Cs, and 60Co]. The polymer was found to decrease the heaviness of the shielding material and increase the flexibility while the metal oxide fillers acted as principle radiation attenuators in the polymer composite. The prepared composites were characterized by Fourier transform infrared spectrophotometer (FT-IR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), scanning electron microscope (SEM), Brunauer-Emmett-Teller surface area (BET) and field emission transmission electron microscope (FE-TEM). The morphological analysis of the assembled composites showed that, PbO NPs and PbO Blk materials exhibited homogenous dispersion in the polymer-matrix. Thermogravimetric analysis (TGA) demonstrated that the thermal-stability of HD-PE was enhanced in the presence of both PbO Blk and PbO NPs. The results declared that, the density of polymer composites was increase with the percentage of filler contents. The highest density value was identified as 1.652 g cm-3 for 50 wt% of PbO NPs. Linear attenuation coefficients (μ) have been estimated from the use of XCOM code and measured results. Reasonable agreement was attended between theoretical and experimental results. These composites were also found to display excellent percentage of heaviness with respect to other conventional materials.

Left Ventricular Retraining and Double Switch in Patients With Congenitally Corrected Transposition of the Great Arteries.

PubMed

Ibrahimiye, Ali N; Mainwaring, Richard D; Patrick, William L; Downey, Laura; Yarlagadda, Vamsi; Hanley, Frank L

2017-03-01

Congenitally corrected transposition of the great arteries (CC-TGA) is a complex form of congenital heart defect with numerous anatomic subgroups. The majority of patients with CC-TGA are excellent candidates for a double-switch procedure. However, in the absence of an unrestrictive ventricular septal defect or subpulmonary stenosis, the left ventricle (LV) may undergo involution and require retraining prior to double switch. The purpose of this study was to review our experience with patients having CC-TGA who required LV retraining prior to a double-switch procedure. This was a retrospective review of 24 patients with CC-TGA who were enrolled in an LV retraining program in preparation for a double-switch procedure. The median age at the time of enrollment for retraining was 11 months (range 1 month-24 years). The average left ventricle to right ventricle pressure ratio was 0.39 ± 0.07 prior to intervention. All 24 patients underwent placement of an initial pulmonary artery band (PAB) for LV retraining. Eighteen (75%) of the 24 patients underwent a double-switch procedure with no operative mortality. Of these 18 patients, 9 had a single PAB and 9 required a second band for retraining. Six patients have not undergone a double-switch procedure to date. Five patients are good candidates for a double switch and are 2 weeks, 3 weeks, 4 weeks, 8 months, and 35 months since their last PAB. One patient died from a noncardiac cause 26 months after PAB retightening. The 18 patients who underwent a double switch were followed for an average of 5 ± 1 years (range 0.1-10.3 years). There has been no late mortality, and only 2 patients required further reinterventions. The data demonstrate that LV retraining has been highly effective in this select group of patients with CC-TGA. The data also demonstrate that the results of the double-switch procedure have been excellent at midterm follow-up. These results suggest that LV retraining and double switch offer a reliable strategy option for patients with CC-TGA.

Microvascular Autonomic Composites

DTIC Science & Technology

2012-01-06

thermogravimetric analysis (TGA) was employed. The double wall allowed for increased thermal stability of the microcapsules, which was...fluorescent nanoparticles (Berfield et al. 2006). Digital Image Correlation (DIC) is a data analysis method, which applies a mathematical...Theme IV: Experimental Assessment & Analysis 2.4.1 Optical diagnostics for complex microfluidic systems pg. 50 2.4.2 Fluorescent thermometry

Liposomes coated with thiolated chitosan enhance oral peptide delivery to rats.

PubMed

Gradauer, K; Barthelmes, J; Vonach, C; Almer, G; Mangge, H; Teubl, B; Roblegg, E; Dünnhaupt, S; Fröhlich, E; Bernkop-Schnürch, A; Prassl, R

2013-12-28

The aim of the present study was the in vivo evaluation of thiomer-coated liposomes for an oral application of peptides. For this purpose, salmon calcitonin was chosen as a model drug and encapsulated within liposomes. Subsequently, the drug loaded liposomes were coated with either chitosan-thioglycolic acid (CS-TGA) or an S-protected version of the same polymer (CS-TGA-MNA), leading to an increase in the particle size of about 500 nm and an increase in the zeta potential from approximately -40 mV to a maximum value of about +44 mV, depending on the polymer. Coated liposomes were demonstrated to effectively penetrate the intestinal mucus layer where they came in close contact with the underlying epithelium. To investigate the permeation enhancing properties of the coated liposomes ex vivo, we monitored the transport of fluoresceinisothiocyanate-labeled salmon calcitonin (FITC-sCT) through rat small intestine. Liposomes coated with CS-TGA-MNA showed the highest effect, leading to a 3.8-fold increase in the uptake of FITC-sCT versus the buffer control. In vivo evaluation of the different formulations was carried out by the oral application of 40 μg of sCT per rat, either encapsulated within uncoated liposomes, CS-TGA-coated liposomes or CS-TGA-MNA-coated liposomes, or given as a solution serving as negative control. The blood calcium level was monitored over a time period of 24h. The highest reduction in the blood calcium level, to a minimum of 65% of the initial value after 6h, was achieved for CS-TGA-MNA-coated liposomes. Comparing the areas above curves (AAC) of the blood calcium levels, CS-TGA-MNA-coated liposomes led to an 8.2-fold increase compared to the free sCT solution if applied orally in the same concentration. According to these results, liposomes coated with S-protected thiomers have demonstrated to be highly valuable carriers for enhancing the oral bioavailability of salmon calcitonin. © 2013. Published by Elsevier B.V. All rights reserved.

Ductal recanalization and stenting for late presenters with TGA intact ventricular septum

PubMed Central

Kothari, Shyam S; Ramakrishnan, Sivasubramanian; Senguttuvan, Nagendra Boopathy; Gupta, Saurabh Kumar; Bisoi, Akshay K

2011-01-01

Introduction: The ideal management strategy for patients presenting late with transposition of great arteries (TGA), intact ventricular septum (IVS), and regressed left ventricle (LV) is not clear. Primary switch, two-stage switch, and Senning operation are the options. Left ventricular retraining prior to arterial switch by ductal stenting may be effective, but the experience is very limited. Methods: Five of six children aged 3–6 months with TGA-IVS and regressed LV underwent recanalization and transcatheter stenting of ductus arteriosus. The ductal stent was removed during arterial switch surgery. Results: The procedure was successful in 5/6 patients. All the patients had totally occluded ductus and needed recanalization with coronary total occlusion hardware. The ductus was dilated and stented with coronary stents. In all the patients, there was significant luminal narrowing despite adequate stent placement and deployment. Two patients needed reintervention for abrupt closure of the stent. Ductal stenting resulted in left ventricular preparedness within 7–14 days. One patient died of progressive sepsis after 14 days of stenting, even though the LV was prepared. Four patients underwent successful uneventful arterial switch surgery. During surgery, it was observed that the mucosal folds of duct were protruding through the struts of the stent in one patient. Conclusions: Ductal stenting is a good alternative strategy for left ventricular retraining in TGA with regressed LV even in patients with occluded ducts. PMID:21976872

Prepared multifunctional aerogel for high performance supercapacitors and effective adsorbents

NASA Astrophysics Data System (ADS)

Zhang, Yimei; Wang, Fei; Ou, Ping; Zhu, Hao; Zhao, Yalong; Wang, Liquan; Chen, Zhuang; Li, Shuai

2018-05-01

Energy and environment as the current research hots pot, how to effectively combine the two is very important and full of challenge. In this research, we design a new type multifunctional aerogel material, which not only can applied for supuercapacitors, but also acted as adsorbents for adsorb organic pollutant. This multifunctional aerogel was prepared by one-pot hydrothermal and freeze-drying method based on elongated TiO2 nanotubes (eTNTs) and graphene. During the hydrothermal process, the graphene nanosheets and eTNTs self-assembled into three-dimensional (3D) interconnected networks, in which the eTNTs with uniform size are intercalate the pore interconnected framework. The results show that the as-prepared eTNTs/graphene aerogel (TGA) exhibits a high specific surface area of 343.2 m2 g‑1. The highly porous and interconnected 3D nanostructure provided efficient migration of electrolyte ions and electrons, and thus the TGA exhibited excellent electrochemical performance for supercapacitors. The binder free TGA electrode possessed high performance electrochemical properties with an excellent specific capacitance (476.8 F g‑1 at scan rate of 5 mV s‑1), and outstanding cycle stability (92% capacitance retention after 5000 cycles). In addition, the TGA also showed admirable adsorption capacity for organic pollutant of bisphenol A, which reached 523.5 mg g‑1. The excellent electrochemical and adsorption capacities suggest the TGA to be the promising materials application in energy storage and environmental remediation.

Thermal Analysis of Plastics

ERIC Educational Resources Information Center

D'Amico, Teresa; Donahue, Craig J.; Rais, Elizabeth A.

2008-01-01

This lab experiment illustrates the use of differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA) in the measurement of polymer properties. A total of seven exercises are described. These are dry exercises: students interpret previously recorded scans. They do not perform the experiments. DSC was used to determine the…

GIS-based multicriteria overlay analysis in soil-suitability evaluation for cotton (Gossypium spp.): A case study in the black soil region of Central India

NASA Astrophysics Data System (ADS)

Walke, N.; Obi Reddy, G. P.; Maji, A. K.; Thayalan, S.

2012-04-01

In this study an attempt was made to characterize the soils of the Ringanbodi watershed, Nagpur district, Maharashtra, Central India, for soil-suitability evaluation for cotton using geographic information system (GIS)-based multicriteria overlay analysis techniques. The study shows that 8 soil series and 16 soil series associations in the study area and soils were classified into three orders, i.e., Entisol, Inceptisol, and Vertisol. The analysis reveals that the soil associations E-F, F-G, G-H, and H-G are "moderately suitable" (S2), D-E are "marginally to moderately suitable," and C-D are marginally (S3) suitable. However, soils B-C are "not suitable" to "marginally suitable" (N2-S3) and A-B are "unsuitable" (N2) for cultivation of cotton. The area analysis shows that for a cotton crop an area about 966.7 ha (49.1%) of TGA is moderately suitable and classified as S2. An area about 469.9 ha (23.8%) of TGA is marginal to moderately suitable (S3-S2). The marginally suitable soils for cotton are classified as S3 and cover an area about 35.2 ha (1.8%) of TGA. However, a 172.3 ha (8.7%) area is not suitable (N2) to marginally suitable (S3) and a 326.9 (16.6%) area is not suitable (N2) for cotton because of uncorrectable factors like soil depth, slope, etc. The study demonstrated that GIS-based multicriteria overlay analysis of soil thematic parameters will be of immense help in soil-suitability evaluation for cotton.

Carbonic anhydrase-facilitated CO2 absorption with polyacrylamide buffering bead capture

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

Dilmore, Robert; Griffith, Craid; Liu, Zhu

2009-07-01

A novel CO2 separation concept is described wherein the enzyme carbonic anhydrase (CA) is used to increase the overall rate Of CO2 absorption after which hydrated CO2 reacts with regenerable amine-bearing polyacrylamide buffering beads (PABB). Following saturation of the material's immobilized tertiary amines, CA-bearing carrier water is separated and recycled to the absorption stage while CO2-loaded material is thermally regenerated. Process application of this concept would involve operation of two or more columns in parallel with thermal regeneration with low-pressure steam taking place after the capacity of a column of amine-bearing polymeric material was exceeded. PABB CO2- bearing capacity wasmore » evaluated by thermogravimetric analysis (TGA) for beads of three acrylamido buffering monomer ingredient concentrations: 0 mol/kg bead, 0.857 mol/kg bead, and 2 mol/kg bead. TGA results demonstrate that CO2- bearing capacity increases with increasing PABB buffering concentration and that up to 78% of the theoretical CO2- bearing capacity was realized in prepared PABB samples (0.857 mol/kg recipe). The highest observed CO2-bearing capacity of PABB was 1.37 mol of CO2 per kg dry bead. TGA was also used to assess the regenerability Of CO2-loaded PABB. Preliminary results suggest that CO2 is partially driven from PABB samples at temperatures as low as 55 degrees C, with complete regeneration occurring at 100 degrees C. Other physical characteristics of PABB are discussed. In addition, the effectiveness of bovine carbonic anhydrase for the catalysis Of CO2 dissolution is evaluated. Potential benefits and drawbacks of the proposed process are discussed. Published by Elsevier Ltd.« less

Interaction specificity and coexpression of rice NPR1 homologs 1 and 3 (NH1 and NH3), TGA transcription factors and Negative Regulator of Resistance (NRR) proteins.

PubMed

Chern, Mawsheng; Bai, Wei; Ruan, Deling; Oh, Taeyun; Chen, Xuewei; Ronald, Pamela C

2014-06-11

The nonexpressor of pathogenesis-related genes 1, NPR1 (also known as NIM1 and SAI1), is a key regulator of SA-mediated systemic acquired resistance (SAR) in Arabidopsis. In rice, the NPR1 homolog 1 (NH1) interacts with TGA transcriptional regulators and the Negative Regulator of Resistance (NRR) protein to modulate the SAR response. Though five NPR1 homologs (NHs) have been identified in rice, only NH1 and NH3 enhance immunity when overexpressed. To understand why NH1 and NH3, but not NH2, NH4, or NH5, contribute to the rice immune response, we screened TGA transcription factors and NRR-like proteins for interactions specific to NH1 and NH3. We also examined their co-expression patterns using publicly available microarray data. We tested five NHs, four NRR homologs (RHs), and 13 rice TGA proteins for pair-wise protein interactions using yeast two-hybrid (Y2H) and split YFP assays. A survey of 331 inter-family interactions revealed a broad, complex protein interaction network. To investigate preferred interaction partners when all three families of proteins were present, we performed a bridged split YFP assay employing YFPN-fused TGA, YFPC-fused RH, and NH proteins without YFP fusions. We found 64 tertiary interactions mediated by NH family members among the 120 sets we examined. In the yeast two-hybrid assay, each NH protein was capable of interacting with most TGA and RH proteins. In the split YFP assay, NH1 was the most prevalent interactor of TGA and RH proteins, NH3 ranked the second, and NH4 ranked the third. Based on their interaction with TGA proteins, NH proteins can be divided into two subfamilies: NH1, NH2, and NH3 in one family and NH4 and NH5 in the other.In addition to evidence of overlap in interaction partners, co-expression analyses of microarray data suggest a correlation between NH1 and NH3 expression patterns, supporting their common role in rice immunity. However, NH3 is very tightly co-expressed with RH1 and RH2, while NH1 is strongly, inversely co-expressed with RH proteins, representing a difference between NH1 and NH3 expression patterns. Our genome-wide surveys reveal that each rice NH protein can partner with many rice TGA and RH proteins and that each NH protein prefers specific interaction partners. NH1 and NH3 are capable of interacting strongly with most rice TGA and RH proteins, whereas NH2, NH4, and NH5 have weaker, limited interaction with TGA and RH proteins in rice cells. We have identified rTGA2.1, rTGA2.2, rTGA2.3, rLG2, TGAL2 and TGAL4 proteins as the preferred partners of NH1 and NH3, but not NH2, NH4, or NH5. These TGA proteins may play an important role in NH1- and NH3-mediated immune responses. In contrast, NH4 and NH5 preferentially interact with TGAL5, TGAL7, TGAL8 and TGAL9, which are predicted to be involved in plant development.

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

Shivananda, C. S.; Rao, B. Lakshmeesha; Madhukumar, R.

In this work silk fibroin/pullulan blend films have been prepared by solution casting method. The blend films were examined for structural, and thermal properties using X-ray diffraction (XRD), thermogravimatric (TGA) and differential scanning calorimetry (DSC) analysis. The XRD results indicate that with the introduction of pullulan, the interaction between SF and pullulan in the blend films induced the conformation transition of SF films and amorphous phase increases with increasing pullulan ratio. The thermal properties of the blend films were improved significantly in the blend films.

Structural, optical and morphological characterization of Cu-doped α-Fe2O3 nanoparticles synthesized through co-precipitation technique

NASA Astrophysics Data System (ADS)

Lassoued, Abdelmajid; Lassoued, Mohamed Saber; Dkhil, Brahim; Gadri, Abdellatif; Ammar, Salah

2017-11-01

Pure and copper (Cu concentration varying from 2 to 8%) doped hematite (α-Fe2O3) nanocrystals were synthesized through co-precipitation method using simple equipment. X-ray Diffraction (XRD), Transmission Electron Microscopy (TEM), Scanning Electron Microscopy (SEM), Fourier Transform Infra-Red (FT-IR), Raman spectroscopy, Differential Thermal Analysis (DTA), Thermo Gravimetric Analysis (TGA) and Ultraviolet-Visible (UV-Vis) techniques were used to characterize the synthesized samples. XRD measurements confirm that all the prepared nanocrystals consist only in nanocrystalline hematite phase. These results along with TEM and SEM show that the size of the nanoparticles decreases with Cu-doping down to 21 nm. FT-IR confirm the phase purity of the nanoparticles synthesized. The Raman spectroscopy was used not only to prove that we synthesized pure and Cu-doped hematite but also to identify their phonon modes. The TGA showed three mass losses, whereas DTA resulted in three endothermic peaks. The UV-Vis absorption measurements confirm that the decrease of particle size is accompanied by a decrease in the band gap value from 2.12 eV for pure α-Fe2O3 down to 1.91 eV for 8% Cu-doped α-Fe2O3. 8% Cu-doped hematite had the smallest size, the best crystallinity and the lowest band gap.

Oxidation characteristics of gasoline direct-injection (GDI) engine soot: Catalytic effects of ash and modified kinetic correlation

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

Choi, Seungmok; Seong, Heeje

In this paper, experimental analyses are conducted into the GDI soot oxidation characteristics as dependent on engine operating conditions. Soot is sampled at various engine operating conditions of a commercial 2.4 L GDI engine with a naturally aspirated, homogeneous, and stoichiometric operation strategy. The oxidation reactivity, ash composition, and carbon nanostructure of the GDI soot samples are analyzed using thermogravimetric analysis (TGA), scanning electron microscope–energy-dispersive spectroscopy (SEM-EDS), high-resolution transmission electron microscopy (HR-TEM), and Raman spectroscopy. Based on the analyses, a global GDI soot oxidation mechanism is proposed which includes the effects of soluble organic fractions (SOF)/weakly bonded carbon (WBC), andmore » three types of ash on GDI soot oxidation. The results show that GDI soot contains an order of magnitude higher ash fraction than does conventional diesel soot, and oxidation reactivity is significantly enhanced by the catalytic effects of ash, as a function of ash content in soot. A modified empirical kinetic correlation for GDI soot oxidation is suggested on the basis of the results, and the modified kinetic correlation predicts the GDI soot oxidation rate accurately for various engine operation points at wide ranges of soot conversion and temperature without modifying kinetic parameters. The kinetic parameters are determined from isothermal and non-isothermal thremogravimetric analysis (TGA) soot oxidation tests; the methods are elucidated in detail.« less

Oxidation characteristics of gasoline direct-injection (GDI) engine soot: Catalytic effects of ash and modified kinetic correlation

DOE PAGES

Choi, Seungmok; Seong, Heeje

2015-03-02

In this paper, experimental analyses are conducted into the GDI soot oxidation characteristics as dependent on engine operating conditions. Soot is sampled at various engine operating conditions of a commercial 2.4 L GDI engine with a naturally aspirated, homogeneous, and stoichiometric operation strategy. The oxidation reactivity, ash composition, and carbon nanostructure of the GDI soot samples are analyzed using thermogravimetric analysis (TGA), scanning electron microscope–energy-dispersive spectroscopy (SEM-EDS), high-resolution transmission electron microscopy (HR-TEM), and Raman spectroscopy. Based on the analyses, a global GDI soot oxidation mechanism is proposed which includes the effects of soluble organic fractions (SOF)/weakly bonded carbon (WBC), andmore » three types of ash on GDI soot oxidation. The results show that GDI soot contains an order of magnitude higher ash fraction than does conventional diesel soot, and oxidation reactivity is significantly enhanced by the catalytic effects of ash, as a function of ash content in soot. A modified empirical kinetic correlation for GDI soot oxidation is suggested on the basis of the results, and the modified kinetic correlation predicts the GDI soot oxidation rate accurately for various engine operation points at wide ranges of soot conversion and temperature without modifying kinetic parameters. The kinetic parameters are determined from isothermal and non-isothermal thremogravimetric analysis (TGA) soot oxidation tests; the methods are elucidated in detail.« less

Influent of Borax Decahydrate Composition as Additional Flux into Stoneware Bodies

NASA Astrophysics Data System (ADS)

Bakil, Siti Natrah Abd; Hussin, Rosniza; Bakar Aramjat, Abu

2017-08-01

Stoneware is vitrified, has less porosity and requires high sintering temperature. The influent of borax decahydrate composition at sintering temperature 1050°C and 1150°C on the thermal analysis, fracture surface, linear shrinkage, water absorption and modular of rapture (MOR) were investigated. Rectangular sample were produced by uniaxially pressing at 40MPa. The thermal behavior was determined by thermogravimetric and different thermal analysis (TGA-DTA). The Scanning electron microscopy (SEM) was used for fracture surface analysis. The water absorption (%) of the sample were determined using Archimedes’ method. The experimental result showed that content of borax decahydrate have influent the properties of stoneware bodies.

Thermal and mechanical analysis of PVA / sulfonated carbon nanotubes composite

NASA Astrophysics Data System (ADS)

Yadav, Vikrant; Sharma, Prem P.; Rajput, Abhishek; Kulshrestha, Vaibhav

2018-04-01

Nanocomposites of polyvinyl alcohol (PVA) and sulfonated carbon nanotubes (s-CNT) with enhanced properties were synthesized successfully. Effect of different amount of sulfonated nanotubes on thermal and mechanical properties of resultant nanocomposites derived from s-CNT and PVA were studied. Structural analysis for functionalization of CNT was done by using FTIR spectra. Thermal and mechanical analysis were done by using TGA, DSC and UTM. Nanocomposite containing s-CNT shows higher elastic moduli, higher melting temperature in consort with lower weight loss at same temperature, compared with pristine PVA. The novelty of this work is to use PVA/s-CNT based composites with improved thermomechanical properties in different nanotechnologies.

Miscibility and thermal behavior of poly (ε-caprolactone)/long-chain ester of cellulose blends

Treesearch

Yuzhi Xu; Chunpeng Wang; Nicole M. Stark; Zhiyong Cai; Fuxiang Chu

2012-01-01

The long-chain cellulose ester (LCCE) cellulose laurate, poly(ε-caprolactone) (PCL) and their blends were characterized by tensile strength, Fourier transform infrared spectroscopy (FTIR), dynamic mechanical thermal analysis, thermogravimetric analysis (TGA), and transmission electron microscopy (TEM). The compatibility of the blends was...

Thermal characterization and model free kinetics of aged epoxies and foams using TGA and DSC methods.

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

Cordaro, Joseph Gabriel; Kruizenga, Alan Michael; Nissen, April

2013-10-01

Two classes of materials, poly(methylene diphenyl diisocyanate) or PMDI foam, and cross-linked epoxy resins, were characterized using thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC), to help understand the effects of aging and %E2%80%9Cbake-out%E2%80%9D. The materials were evaluated for mass loss and the onset of decomposition. In some experiments, volatile materials released during heating were analyzed via mass spectroscopy. In all, over twenty materials were evaluated to compare the mass loss and onset temperature for decomposition. Model free kinetic (MFK) measurements, acquired using variable heating rate TGA experiments, were used to calculate the apparent activation energy of thermal decomposition.more » From these compiled data the effects of aging, bake-out, and sample history on the thermal stability of materials were compared. No significant differences between aged and unaged materials were detected. Bake-out did slightly affect the onset temperature of decomposition but only at the highest bake-out temperatures. Finally, some recommendations for future handling are made.« less

New Generation Materials and Structures for Nanophotonics and Nanoelectronics

DTIC Science & Technology

2006-04-30

been investigated using thermogravimetric analysis and FTIR spectroscopy. The nanoparticles appear to have excess surfactants on their surface, but...processes. We continued analysis of the vibrational modes of the InP/II- VI core-shell nanoparticles determined by IR and Raman studies, and initiated...photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), BET surface area analysis , transmission electron microscopy (TEM), and SQUID magnetometry. In

Study of thermal decomposition mechanisms and low-level detection of explosives using pulsed photoacoustic technique

NASA Astrophysics Data System (ADS)

Yehya, F.; Chaudhary, A. K.; Srinivas, D.; Muralidharan, K.

2015-11-01

We report a novel time-resolved photoacoustic-based technique for studying the thermal decomposition mechanisms of some secondary explosives such as RDX (hexahydro-1,3,5-trinitro-1,3,5-triazine), picric acid, 4,6-dinitro-5-(4-nitro-1 H-imidazol-1-yl)-1 H-benzo[ d] [1-3] triazole, and 5-chloro-1-(4-nitrophenyl)-1 H-tetrazole. A comparison of the thermal decomposition mechanisms of these secondary explosives was made by detecting NO2 molecules released under controlled pyrolysis between 25 and 350 °C. The results show excellent agreement with the thermogravimetric and differential thermal analysis (TGA-DTA) results. A specially designed PA cell made of stainless steel was filled with explosive vapor and pumped using second harmonic, i.e., λ = 532 nm, pulses of duration 7 ns at a 10 Hz repetition rate, obtained using a Q-switched Nd:YAG laser. The use of a combination of PA and TGA-DTA techniques enables the study of NO2 generation, and this method can be used to scale the performance of these explosives as rocket fuels. The minimum detection limits of the four explosives were 38 ppmv to 69 ppbv, depending on their respective vapor pressures.

Measurements for the BETC in-situ combustion experiment. [Post test surveys

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

Wayland, J.R.; Bartel, L.C.

The Bartlesville Energy Technology Center (BETC) in situ combustion pilot project near Bartlette, Kansas, was studied using controlled source audio-magnetotelluric (CSAMT) mapping, thermal gravimetric analysis (TGA), conventional geophysical logging and modeling of the fireflood. Measurements of formation resistivity changes induced by in situ combustion indicate that CSAMT resistivity maps should show an increase in apparent resistivity. The substantial decrease of apparent resistivity measured within the five spot pattern indicated a complex sequence of events. Using the results from the CSAMT surveys the fire front was located and posttest core samples were obtained. The posttest core samples were examined using TGAmore » techniques, and using information from combustion tube runs as standards, the location of the fire front in the core samples from the posttest holes was inferred. Models of the reservoir in situ combustion process were developed to help analyze the field results. The combustion kinematics, when used in conjunction with CSAMT and TGA techniques, indicated that considerable bypass of injected air occurred with an influx of brine into previously burned zones. This experiment offered an opportunity to integrate several new techniques into a systematic study of a difficult problem.« less

Structural, Morphological, Differential Scanning Calorimetric and Thermogravimetric Studies of Ball Milled Fe Doped Nanoscale La0.67Sr0.33MnO3 Manganite

NASA Astrophysics Data System (ADS)

Astik, Nidhi; Jha, Prafulla K.; Pratap, Arun

2018-03-01

The ball milling route has been used to produce the La0.67Sr0.33Mn0.85Fe0.15O3 (LSMFO) nanocrystalline sample from oxide precursors. The sample was characterized using x-ray diffraction (XRD), a scanning electron microscope (SEM), energy dispersive x-ray spectroscopy (EDAX), differential scanning calorimetry (DSC) and thermogravimetric (TGA) measurements. The x-ray diffraction confirms the phase purity of sample and shows that the sample crystallizes in the rhombohedral perovskite structure with a R-3c space group. The scanning electron micrograph shows the presence of well-faceted crystallites of LSMFO. The EDAX spectrum demonstrates the molar ratio of different elements of nanocrystalline LSMFO. Furthermore, the crystallite size using the Debye-Scherrer formula and William-Hall analysis has been found as 24 nm and 29 nm, respectively. Our results support the idea that a good quality nanocrystalline LSMFO sample can be obtained using the ball milling route. We also discuss the DSC and TGA curves and analyse the results in terms of phase transition, calcination temperature and activation barrier energies.

Acrylonitrile butadiene rubber (NBR)/manganous tungstate (MnWO4) nanocomposites: Characterization, mechanical and electrical properties

NASA Astrophysics Data System (ADS)

Ramesan, M. T.; Abdu Raheem V., P.; Jayakrishnan, P.; Pradyumnan, P. P.

2014-10-01

Nanocomposites of NBR with manganous-tungstate nanoparticles were prepared through vulcanization process. The extent of interaction of nanoparticles with the polymer was studied by FTIR, SEM, XRD, TGA and AC conductivity. FTIR and XRD ascertain the interaction of NBR with MnWO4 nanoparticles. SEM analysis established that the nanopartilces were well dispersed in the macromolecular chain of NBR. The mechanical properties of the nanocomposites were studied as a function of filler loading. The nanocomposites exhibited enhanced thermal stability as seen in TGA. Conductivity and dielectric properties of nanocomposites increase with increase in concentration of MnWO4 nanoparticles (7phr) and thereafter the value decreases.

Mental simulation of future scenarios in transient global amnesia.

PubMed

Juskenaite, Aurelija; Quinette, Peggy; Desgranges, Béatrice; de La Sayette, Vincent; Viader, Fausto; Eustache, Francis

2014-10-01

Researchers exploring mental time travel into the future have emphasized the role played by episodic memory and its cerebral substrates. Recently, owing to controversial findings in amnesic patients, this role has become a matter of intense debate. In order to understand whether episodic memory is indeed crucial to future thinking, we assessed this ability in 11 patients during an episode of transient global amnesia (TGA), a unique and severe amnesic syndrome that primarily affects episodic memory. In the first of two experiments, TGA patients were asked to recall personal past events as well as to imagine personal future events, without any guidance regarding content. Under this condition, compared with controls, they provided fewer past and fewer future events, and the latter were less closely related to their personal goals. Furthermore, TGA patients׳ descriptions of past and future events were scant, containing fewer descriptive elements in total and fewer internal details. In order to assess whether TGA patients might have been basing their future event narratives on their general knowledge about how these events usually unfold, in our second experiment, we asked them to imagine future events in response to short descriptions of common scenarios. Under this condition, inherently eliciting less detailed descriptions, not only were all the TGA patients able to describe common events as happening in the future, but their narratives contained comparable amounts of internal detail to those of controls, despite being less detailed overall. Taken together, our results indicate that severe amnesia interferes with TGA patients׳ ability to envisage their personal past and future on a general level as well as in detail, but less severely affects their ability to imagine common scenarios, which are not related to their personal goals, probably owing to their preserved semantic memory, logical reasoning and ability to create vivid mental images. Copyright © 2014 Elsevier Ltd. All rights reserved.

Identification of Non-HLA Genes Associated with Celiac Disease and Country-Specific Differences in a Large, International Pediatric Cohort.

PubMed

Sharma, Ashok; Liu, Xiang; Hadley, David; Hagopian, William; Liu, Edwin; Chen, Wei-Min; Onengut-Gumuscu, Suna; Simell, Ville; Rewers, Marian; Ziegler, Anette-G; Lernmark, Åke; Simell, Olli; Toppari, Jorma; Krischer, Jeffrey P; Akolkar, Beena; Rich, Stephen S; Agardh, Daniel; She, Jin-Xiong

2016-01-01

There are significant geographical differences in the prevalence and incidence of celiac disease that cannot be explained by HLA alone. More than 40 loci outside of the HLA region have been associated with celiac disease. We investigated the roles of these non-HLA genes in the development of tissue transglutaminase autoantibodies (tTGA) and celiac disease in a large international prospective cohort study. A total of 424,788 newborns from the US and European general populations and first-degree relatives with type 1 diabetes were screened for specific HLA genotypes. Of these, 21,589 carried 1 of the 9 HLA genotypes associated with increased risk for type 1 diabetes and celiac disease; we followed 8676 of the children in a 15 y prospective follow-up study. Genotype analyses were performed on 6010 children using the Illumina ImmunoChip. Levels of tTGA were measured in serum samples using radio-ligand binding assays; diagnoses of celiac disease were made based on persistent detection of tTGA and biopsy analysis. Data were analyzed using Cox proportional hazards analyses. We found 54 single-nucleotide polymorphisms (SNPs) in 5 genes associated with celiac disease (TAGAP, IL18R1, RGS21, PLEK, and CCR9) in time to celiac disease analyses (10-4>P>5.8x10-6). The hazard ratios (HR) for the SNPs with the smallest P values in each region were 1.59, 1.45, 2.23, 2.64, and 1.40, respectively. Outside of regions previously associated with celiac disease, we identified 10 SNPs in 8 regions that could also be associated with the disease (P<10-4). A SNP near PKIA (rs117128341, P = 6.5x10-8, HR = 2.8) and a SNP near PFKFB3 (rs117139146, P<2.8x10-7, HR = 4.9) reached the genome-wide association threshold in subjects from Sweden. Analyses of time to detection of tTGA identified 29 SNPs in 2 regions previously associated with celiac disease (CTLA4, P = 1.3x10-6, HR = 0.76 and LPP, P = 2.8x10-5, HR = .80) and 6 SNPs in 5 regions not previously associated with celiac disease (P<10-4); non-HLA genes are therefore involved in development of tTGA. In conclusion, using a genetic analysis of a large international cohort of children, we associated celiac disease development with 5 non-HLA regions previously associated with the disease and 8 regions not previously associated with celiac disease. We identified 5 regions associated with development of tTGA. Two loci associated with celiac disease progression reached a genome-wide association threshold in subjects from Sweden.

Development of Composite PCMs by Incorporation of Paraffin into Various Building Materials

PubMed Central

Memon, Shazim Ali; Liao, Wenyu; Yang, Shuqing; Cui, Hongzhi; Shah, Syed Farasat Ali

2015-01-01

In this research, we focused on the development of composite phase-change materials (CPCMs) by incorporation of a paraffin through vacuum impregnation in widely used building materials (Kaolin and ground granulated blast-furnace slag (GGBS)). The composite PCMs were characterized using environmental scanning electron microscopy (ESEM), Fourier transform infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) techniques. Moreover, thermal performance of cement paste composite PCM panels was evaluated using a self-designed heating system. Test results showed that the maximum percentage of paraffin retained by Kaolin and GGBS was found to be 18% and 9%, respectively. FT-IR results show that CPCMs are chemically compatible. The phase-change temperatures of CPCMs were in the human comfort zone, and they possessed considerable latent-heat storage capacity. TGA results showed that CPCMs are thermally stable, and they did not show any sign of degradation below 150 °C. From thermal cycling tests, it was revealed that the CPCMs are thermally reliable. Thermal performance tests showed that in comparison to the control room model, the room models prepared with CPCMs reduced both the temperature fluctuations and maximum indoor center temperature. Therefore, the prepared CPCMs have some potential in reducing peak loads in buildings when applied to building facade. PMID:28787953

Features of the Valorization of Single and Double Based Powders for Codetonation in Emulsion Explosives

NASA Astrophysics Data System (ADS)

Ribeiro, Jose; Mendes, Ricardo; Tavares, Bruno; Louro, Cristina

2013-06-01

In this work, features of the thermal and detonation behavior of compositions resulting from the mixture of single and double based gun powder within ammonium nitrate (AN) based emulsion explosives are shown. That includes results of thermodynamic-equilibrium calculations of the detonation velocity, the chemical compatibility assessment through differential scanning calorimetry [DSC] and thermo gravimetric analysis [TGA], the experimental determination of the detonation velocity and a comparative evaluation of the shock sensitivity using a modified version of the ``gap-test''. DSC/TGA results for the compositions and for the individual components overlap until the beginning of the thermal decomposition which is an indication of the absence of formation of any new chemical specimens and so of the capability of the composition components. After the beginning of the thermal decomposition it can be seen that the rate of mass loss is much higher for the compositions with gun powder than for the sole emulsion explosive. Both, theoretical and experimental, values of the detonation velocity have shown to be higher for the powdered compositions than for the pure emulsion explosive. Shock sensitivity assessment have ended-up with a slightly bigger sensitivity for the compositions with double based gun powder when compared to the single based compositions or to the pure emulsion.

TGA, Hirshfeld, Raman spectroscopy and computational studies of diethylammonium hexachloroplumbate [(C2H5)2NH2]2PbCl6

NASA Astrophysics Data System (ADS)

Ouasri, A.; El-Adel, L.; Zouihri, H.; Rhandour, A.; Jalbout, A. F.

2018-04-01

Diethylammonium hexachloroplumbate [(C2H5)2NH2]2PbCl6 was found to be monoclinic with P21/n (Z = 2) as space group at room temperature. The TGA analysis shows that this compound is slightly hygroscopic and presents moisture in itself. The Raman spectrum (50-4000 cm-1) of this compound recorded at room temperature was discussed on the basis of the factor group analysis using the structural data obtained recently [5]. The experimental frequencies are compared to those obtained by Density Functional Theory (DFT) by using the B3LYP functional and the 6-31G(d) (SDD) basis set. The thermodynamic properties and geometries of this compound have been determinated and characterized. The significant intermolecular interactions in the crystal structure are identified and analyzed using the Hirshfeld surface and fingerprint plots computational methods.

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

Madhukumar, R.; Asha, S.; Rao, B. Lakshmeesha

The gamma radiation-induced change in structural and thermal properties of Bombyx mori silk fibroin films were investigated and have been correlated with the applied radiation doses. Irradiation of samples were carried out in dry air at room temperature using Co-60 source, and radiation doses are in the range of 0 - 300 kGy. Structural and thermal properties of the irradiated silk films were studied using X-ray diffraction (XRD), Differential Scanning Calorimetry (DSC) and Thermogravimetric analysis (TGA) and compared with unirradiated sample. Interesting results are discussed in this report.

PVP capped CdS nanoparticles for UV-LED applications

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

Sivaram, H.; Selvakumar, D.; Jayavel, R., E-mail: rjvel@annauniv.edu

Polyvinlypyrrolidone (PVP) capped cadmium sulphide (CdS) nanoparticles are synthesized by wet chemical method. The powder X-ray diffraction (XRD) result indicates that the nanoparticles are crystallized in cubic phase. The optical properties are characterized by UV-Vis absorption. The morphology of CdS nanoparticles are studied using Scanning electron microscope (SEM). The thermal behavior of the as prepared nanoparticles has been examined by Thermo gravimetric analysis (TGA). The optical absorption study of pvp capped CdS reveal a red shift confirms the UV-LED applications.

Promising SiC support for Pd catalyst in selective hydrogenation of acetylene to ethylene

NASA Astrophysics Data System (ADS)

Guo, Zhanglong; Liu, Yuefeng; Liu, Yan; Chu, Wei

2018-06-01

In this study, SiC supported Pd nanoparticles were found to be an efficient catalyst in acetylene selective hydrogenation reaction. The ethylene selectivity can be about 20% higher than that on Pd/TiO2 catalyst at the same acetylene conversion at 90%. Moreover, Pd/SiC catalyst showed a stable catalytic life at 65 °C with 80% ethylene selectivity. With the detailed characterization using temperature-programmed reduction (H2-TPR), powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), N2 adsorption/desorption analysis, CO-chemisorption and thermo-gravimetric analysis (TGA), it was found that SiC owns a lower surface area (22.9 m2/g) and a broad distribution of meso-/macro-porosity (from 5 to 65 nm), which enhanced the mass transfer during the chemical process at high reaction rate and decreased the residence time of ethylene on catalyst surface. Importantly, SiC support has the high thermal conductivity, which favored the rapid temperature homogenization through the catalyst bed and inhabited the over-hydrogenation of acetylene. The surface electronic density of Pd on Pd/SiC catalyst was higher than that on Pd/TiO2, which could promote desorption of ethylene from surface of the catalyst. TGA results confirmed a much less coke deposition on Pd/SiC catalyst.

Thiolated chitosan: development and in vivo evaluation of an oral delivery system for leuprolide.

PubMed

Iqbal, Javed; Shahnaz, Gul; Perera, Glen; Hintzen, Fabian; Sarti, Federica; Bernkop-Schnürch, Andreas

2012-01-01

The aim of the present study was to develop an oral delivery system for the peptide drug leuprolide. Gel formulations based on unmodified chitosan/reduced glutathione (GSH) and chitosan-thioglycolic acid (chitosan-TGA)/GSH were prepared, and their effect on the absorption of leuprolide was evaluated in vitro and in vivo in male Sprague Dawley rats. Transport studies were performed with freshly excised rat intestinal mucosa mounted in Ussing-type chambers. Due to the addition of gel formulations comprising 0.5% (m/v) unmodified chitosan/0.5% (m/v) GSH and 0.5% (m/v) chitosan-TGA/0.5% (m/v) GSH, the transport of leuprolide across excised mucosa was improved up to 2.06-fold and 3.79-fold, respectively, in comparison with leuprolide applied in buffer (P(app)=2.87 ± 0.77 × 10⁻⁶ cm/s). In vivo, the addition of oral gel formulation comprising 8 mg of unmodified chitosan, 1mg of GSH and 1mg of leuprolide increased the area under the plasma concentration-time curve (AUC₀₋₈) of leuprolide 1.39-fold in comparison with leuprolide having been administered just in saline. Moreover, the administration of oral gel formulation comprising 8 mg of chitosan-TGA, 1mg of GSH and 1mg of leuprolide resulted in a further enhanced leuprolide plasma concentration, and the area under the plasma concentration-time curve (AUC₀₋₈) of leuprolide was increased 3.72-fold in comparison with the control. With the oral gel formulation comprising 8 mg of chitosan-TGA, a relative bioavailability (versus s.c. injection) of 4.5% was achieved in contrast to the control displaying a relative bioavailability of 1.2%. Thus, according to the achieved results, it is suggested that chitosan-TGA in combination with GSH is a valuable tool for improving the oral bioavailability of the peptide drug leuprolide. Copyright © 2011 Elsevier B.V. All rights reserved.

Iron oxide nanoparticles modified with silanes for hyperthermia applications

NASA Astrophysics Data System (ADS)

Storozhuk, Liudmyla; Iukhymenko, Natalia

2018-04-01

Fe3O4-HDTMS nanocomposites were prepared and studied using Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy, X-ray analysis, thermal analysis (TGA), dynamic light scattering analysis, magnetic and specific loss power (SLP) measurements. FTIR results showed that during the modification, the formation of the silane coating occurs due to the appearance of the magnetite-O-Si-R bond. According to TGA results, the mass loss in the range of temperatures 410-650 °C is due to the destruction of covalent bonds Fe-O-Si. The Si-O-R coating leads to the decrease in the absolute value of the effective saturation magnetization due to the presence of a non-magnetic phase (coating) in the sample, but the coercivity increases with the coating thickness due to higher effective values of the magnetic anisotropy of the magnetostrictive nature. The thermal response of NP-based dispersions in silicone and oleic acid was shown that SLP value is higher for magnetic material dispersions in Lipiodol and oleic acid compared to silicone-based dispersions. This can be explained by the contribution of both Neel and Brownian relaxation processes. However, in the case of silicone-based dispersion, Brownian relaxation is negligible because of NP immobilization in viscous silicone matrix. As it is to the effect of coating on SLP, this is clearly evident in the case of silicone dispersions. The study of the heating ability of dispersions based on HDTMS-modified Fe3O4 NPs showed that the coating does not significantly decrease the SLP values.

Elimination of Perchlorate Oxidizers from Pyrotechnic Flare Compositions

DTIC Science & Technology

2007-03-09

in candelas ( cd ), where the candela is defined as, 1 cd = 1 lumen /steradian-1. DSC A thermal analysis technique known as Differential...Shorter Wavelength Infrared band routinely monitored in decoy flare performance tests. TGA A thermal analysis technique known as Thermogravimetric ...Scanning Calorimetry DTA A thermal analysis technique known as Differential Thermal Analysis GAP Glycidyl Azide Polymer used as a curable binder in some

Thermogravimetric analysis of forest understory grasses

Treesearch

Thomas Elder; John S. Kush; Sharon M. Hermann

2011-01-01

Forest understory grasses are of significance in the initiation, establishment and maintenance of fire, whether used as a management tool or when occurring as wildfire. The fundamental thermal properties of such grasses are critical to their behavior in fire situations and have been investigated in the current work by the application of thermogravimetric analysis (TGA...

Optical properties of hydrothermally synthesized TGA-capped CdS nanoparticles: controlling crystalline size and phase

NASA Astrophysics Data System (ADS)

Tavakoli Banizi, Zoha; Seifi, Majid

2017-10-01

TGA-capped CdS nanoparticles were obtained in the presence of thioglycolic acid (TGA) as capping agent via a facile hydrothermal method at relatively low temperature and over a short duration. As-synthesized TGA-capped CdS nanoparticles were characterized by x-ray diffraction, scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectra, photoluminescence spectroscopy, Ultraviolet-visible spectroscopy and energy-dispersive x-ray spectroscopy. The products had spherical shapes, although their crystalline size and phase was dependent on temperature and time of the reaction. Photoluminescence spectra showed that the fluorescence intensity decreased when increasing the reaction time and temperature.

Frequent Activation Delay-Induced Mechanical Dyssynchrony and Dysfunction in the Systemic Right Ventricle.

PubMed

Forsha, Daniel; Risum, Niels; Smith, P Brian; Kanter, Ronald J; Samad, Zainab; Barker, Piers; Kisslo, Joseph

2016-11-01

Patients with systemic right ventricles frequently experience progressive heart failure and conduction abnormalities leading to abnormal ventricular activation. Activation delay-induced mechanical dyssynchrony can contribute to ventricular failure and is identified by a classic strain pattern of paradoxical opposing wall motion that is an excellent predictor of response to cardiac resynchronization therapy in adults with left bundle branch block. The specific aims of this study were to compare right ventricular (RV) mechanics in an adult systemic right ventricle population versus control subjects, evaluate the feasibility of this RV strain pattern analysis, and determine the frequency of the classic pattern. Young adults (n = 25) with d-transposition of the great arteries, status post Mustard or Senning palliation (TGA-MS), were ambispectively enrolled and compared with healthy young adults (n = 30) who were prospectively enrolled. All subjects were imaged using novel three-apical view (18-segment) RV longitudinal speckle-tracking strain analysis (EchoPAC) and electrocardiographic data. Patients with TGA-MS had diminished RV global peak systolic strain compared with control subjects (-12.0 ± 4.0% vs -23.3 ± 2.3%, P < .001). Most patients with TGA-MS had intrinsic or left ventricular paced right bundle branch block. A classic pattern was present in 11 of 25 subjects (44%), but this pattern would have been missed in four of 11 based only on the RV four-chamber (six-segment) model. Only three subjects underwent cardiac resynchronization therapy. Both subjects who had the classic pattern responded to cardiac resynchronization therapy, whereas the one nonresponder did not have the classic pattern. Systemic right ventricles demonstrated decreased function and increased mechanical dyssynchrony. The classic pattern of activation delay-induced mechanical dyssynchrony was frequently seen in this TGA-MS population and associated with activation delays. This comprehensive RV approach demonstrated incremental value. Copyright © 2016 American Society of Echocardiography. Published by Elsevier Inc. All rights reserved.

Reinforcement of poly(amide-imide) containing N-trimellitylimido-L-phenylalanine by using nano α-Al2O3 surface-coupled with bromo-flame retardant under ultrasonic irradiation technique

NASA Astrophysics Data System (ADS)

Mallakpour, Shadpour; Khadem, Elham

2014-10-01

By the uniform dispersion of nanoparticles into a polymer matrix, a substantial improvement of physicochemical properties can be attained. In this study, a series of poly(amide-imide)/Al2O3 nanocomposites (PANC)s based on various amounts of modified α-Al2O3 nanoparticles (ANP)s were prepared using the ultrasonic irradiation method. In the process of manufacturing the nanocomposites (NC)s, severe agglomeration of ANPs into the polymer matrix can be reduced using 2,3,4,5-tetrabromo-6-[(4-hydroxyphenyl)carbamoyl]benzoic acid as novel coupling agent. The effects of modified ANPs on the morphology and properties of the polymer matrix were studied by means of Fourier transform infrared spectroscopy, X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy and thermal gravimetric analysis (TGA). The results obtained by TGA showed that the thermal stability of the NCs was improved with the addition of the small amounts of ANPs as effective thermal degradation resistant reinforcement.

Flame-retardant polyvinyl alcohol membrane with high transparency based on a reactive phosphorus-containing compound.

PubMed

Peng, Sha; Zhou, Ming; Liu, Feiyan; Zhang, Chang; Liu, Xueqing; Liu, Jiyan; Zou, Liyong; Chen, Jia

2017-08-01

Flame-retardant polyvinyl alcohol (PVA) membranes with high transparency and flexibility were prepared by mixing an aqueous solution of a phosphorus-containing acrylic acid (AOPA) with PVA. The reaction between AOPA and PVA, the transparency, the crystallinity and the flexibility of the membrane were investigated with Fourier transform infrared spectrometry (FTIR), UV-vis light transmittance, X-ray diffraction and tensile tests, respectively. The limited oxygen index (LOI) and vertical flame (UL 94 VTM), microscale combustion calorimetry, thermogravimetric analysis (TGA) and TGA-FTIR were employed to evaluate the flame retardancy as well as to reveal the corresponding mechanisms. Results showed that PVA containing 30 wt% of AOPA can reach the UL 94 VTM V0 rating with an LOI of 27.3% and retain 95% of the original transparency of pure PVA. Adding AOPA reduces crystallinity of PVA, while the flexibility is increased. AOPA depresses the thermal degradation of PVA and promotes char formation during combustion. The proposed decomposition mechanism indicates that AOPA acts mainly in the condensed phase.

Thermal stability and degradation kinetics of kenaf/sol-gel silica hybrid

NASA Astrophysics Data System (ADS)

Yusof, F. A. M.; Hashim, A. S.; Tajudin, Z.

2017-12-01

Thermal stability and degradation kinetics of kenaf/sol-gel silica hybrid materials was investigated by thermogravimetric analysis (TGA). Model-free iso-conversion Flynn-Wall-Ozawa (FWO) and Coats-Redfern-modified (CRm) were chosen to evaluate the activation energy of the kenaf (KF) and kenaf/sol-gel silica (KFS) at heating rates (β) of 10, 20, 30 and 40 °C/min. The results shows that an apparent activation energy was increased for the kenaf/sol-gel silica hybrid (211.59 kJ/mol for FWO and 191.55 kJ/mol for CRm) as compared to kenaf fiber (202.84 kJ/mol for FWO and 186.20 kJ/mol for CRm). Other parameters such as integral procedure decomposition temperature (IPDT), final residual weight (Rf), temperature of maximum degradation rate (Tmax) and residual at maximum temperature (RTmax) were obtained from TGA curves, additionally confirmed the thermal stability of the kenaf/sol-gel silica hybrid. These activation energy values and other findings developed the simplified approach in order to understand the thermal stability and degradation kinetics behavior of kenaf/sol-gel silica hybrid materials.

Influences of metal ions crosslinked alginate based coatings on thermal stability and fire resistance of cotton fabrics.

PubMed

Pan, Ying; Wang, Wei; Liu, Longxiang; Ge, Hua; Song, Lei; Hu, Yuan

2017-08-15

Bio-based and phosphorus-free coating was fabricated by layer-by-layer assembly method to obtain the flame retardant cotton fabric. For the first time, the modified cotton fabrics were prepared by utilizing positively charged polyethylenimine and negatively charged alginate together with subsequent crosslinking of barium, nickel and cobalt ions. Scanning electron microscopy and energy-dispersive X-ray demonstrated that the metal ions crosslinked coating was successfully constructed on the substrate. The thermal stability and flame retardancy were investigated by thermogravimetric analysis (TGA) and horizontal flame tests. TGA results showed that the degradation of the coated cotton fabrics were retarded at high temperature and the char residue of the cotton fabrics were improved after covered with the barium, nickel and cobalt ions crosslinked coatings. Furthermore, the fire resistance of cotton-Ba sample was enhanced significantly compared with the untreated sample, as evidenced by the obvious reduction (28%) of flame spread rate and complete char residue. Finally, the washing durability of coating on the fabric was enhanced after metal ions crosslinked with alginate based coating. Copyright © 2017. Published by Elsevier Ltd.

Progress in Primary Acoustic Thermometry at NIST: 273 K to 505 K

NASA Astrophysics Data System (ADS)

Strouse, G. F.; Defibaugh, D. R.; Moldover, M. R.; Ripple, D. C.

2003-09-01

The NIST Acoustic Thermometer determines the thermodynamic temperature by measuring the speed of sound of argon in a spherical cavity. We obtained the thermodynamic temperature of three fixed points on the International Temperature Scale of 1990: the melting point of gallium [T(Ga) = 302.9146 K] and the freezing points of indium [T(In) = 429.7485 K] and tin [T(Sn) = 505.078 K]. The deviations of thermodynamic temperature from the ITS-90 defined temperatures are T - T90 = (4.7 ± 0.6) mK at T(Ga) , T - T90 = (8.8 ± 1.5) mK at T(In) , and T - T90 = (10.7 ± 3.0) mK at T(Sn) , where the uncertainties are for a coverage factor of k = 1. Our results at T(In) and T(Sn) reduce the uncertainty of T - T90 by a factor of two in this range. Both T - T90 at T(Ga) and the measured thermal expansion of the resonator between the triple point of water and T(Ga) are in excellent agreement with the 1992 determination at NIST. The dominant uncertainties in the present data come from frequency-dependent and time-dependent crosstalk between the electroacoustic transducers. We plan to reduce these uncertainties and extend this work to 800 K.

Spray drying egg using either maltodextrin or nopal mucilage as stabilizer agents.

PubMed

Medina-Torres, L; Calderas, F; Nuñez Ramírez, D M; Herrera-Valencia, E E; Bernad Bernad, M J; Manero, O

2017-12-01

In this work, a comparative study between spray drying (SD) of fresh egg by either maltodextrin (MD) or nopal-mucilage (MN) as stabilizing vectors was made. The powders obtained were characterized for drying performance, moisture content, chemical proximate analysis, thermal analysis (TGA), chemical composition (FTIR), microscopy (SEM) and rheology (viscoelasticity and steady state simple shear viscosity). Infrared analysis showed that MN has the effect of a thickening agent rather than an encapsulating one. Results indicated that SD egg with MN produced a high thermal and mechanical stable product and rendered the highest drying performance, producing a more uniform and defined sphere-shaped morphology in comparison to egg SD either alone and with MD.

Fabrication and Characterization of Multi-Walled Carbon Nanotube (MWCNT) and Ni-Coated Multi-Walled Carbon Nanotube (Ni-MWCNT) Repair Patches for Carbon Fiber Reinforced Composite Systems

NASA Technical Reports Server (NTRS)

Johnson, Brienne; Caraccio, Anne; Tate, LaNetra; Jackson, Dionne

2011-01-01

Multi-walled carbon nanotube (MWCNT)/epoxy and nickel-coated multi-walled carbon nanotube (Ni-MWCNT)/epoxy systems were fabricated into carbon fiber composite repair patches via vacuum resin infusion. Two 4 ply patches were manufactured with fiber orientations of [90/ 90/ 4590] and [0/90/ +45/ -45]. Prior to resin infusion, the MWCNT/Epoxy system and NiMWCNT/ epoxy systems were optimized for dispersion quality. Scanning electron microscopy (SEM) and optical microscopy (OM) were used to determine the presence ofcarbon nanotubes and assess dispersion quality. Decomposition temperatures were determined via thermogravametric analysis (TGA). SEM and TGA were also used to evaluate the composite repair patches.

New monitoring by thermogravimetry for radiation degradation of EVA

NASA Astrophysics Data System (ADS)

Boguski, J.; Przybytniak, G.; Łyczko, K.

2014-07-01

The radiation ageing of ethylene vinyl-acetate copolymer (EVA) as the jacket of cable applied in nuclear power plant was carried out by gamma rays irradiation, and the degradation was monitored by a thermo-gravimetric analysis (TGA). The EVA decomposition rate in air by the isothermal at 400 °C decreased with increase of dose and also with decrease of the dose rate. The behavior of EVA jacket of cable indicated that the decomposition rate at 400 °C was reduced with increase of oxidation. The elongation at break by tensile test for the radiation aged EVA was closely related to the decomposition rate at 400 °C; therefore, the TGA might be applied for a diagnostic technique of the cable degradation.

The Mechanism of Action of Unique Small Molecules that Inhibit the Pim Protein Kinase Blocking Prostate Cancer Cell Growth

DTIC Science & Technology

2010-05-01

shown. (E) Cap-dependent ( gray bars) and IRES-dependent (black bars) translation in MEFs as measured by Renilla and Firefly luciferase activities...AGC ATC AAC C; EPHA2-R, GTG ACC TCG TAC TTC CAC ACT C. HER3-F, CGA TGC TGA GAA CCA ATA CCA G; HER3-R, ATA GCC TGT CAC TTC TCG AAT C. INSR-F, GGA AGT...TAC GTC TGA TTC GAG G; INSR-R, TGA GTG ATG GTG AGG TTG TG. IGF1R-F, CCT GCA CAA CTC CAT CTT CGT G; IGF1R-R, CGG TGA TGT TGT AGG TGT CTG C. EGFR-F

Extraction and characterization of montmorency (Prunus cerasus L.) sour cherry pit oil

USDA-ARS?s Scientific Manuscript database

Montmorency sour cherry (Prunus cerasus L.) pit oil was extracted and characterized by various methods including: gas chromatography (GC), liquid chromatography coupled with mass spectrometry (LC-MS), nuclear magnetic resonance (NMR), thermogravimetric analysis (TGA), differential scanning calorime...

WRKY71 and TGA1a physically interact and synergistically regulate the activity of a novel promoter isolated from Petunia vein-clearing virus.

PubMed

Shrestha, Ankita; Khan, Ahamed; Mishra, Dipti Ranjan; Bhuyan, Kashyap; Sahoo, Bhabani; Maiti, Indu B; Dey, Nrisingha

2018-02-01

Caulimoviral promoters have become excellent tools for efficient transgene expression in plants. However, the transcriptional framework controlling their systematic regulation is poorly understood. To understand this regulatory mechanism, we extensively studied a novel caulimoviral promoter, PV8 (-163 to +138, 301 bp), isolated from Petunia vein-clearing virus (PVCV). PVCV was found to be Salicylic acid (SA)-inducible and 2.5-3.0 times stronger than the widely used CaMV35S promoter. In silico analysis of the PV8 sequence revealed a unique clustering of two stress-responsive cis-elements, namely, as-1 1 and W-box 1-2 , located within a span of 31 bp (-74 to -47) that bound to the TGA1a and WRKY71 plant transcription factors (TFs), respectively. We found that as-1 (TTACG) and W-box (TGAC) elements occupied both TGA1a and WRKY71 on the PV8 backbone. Mutational studies demonstrated that the combinatorial influence of as-1 (-57) and W-box 1-2 (-74 and -47) on the PV8 promoter sequence largely modulated its activity. TGA1a and WRKY71 physically interacted and cooperatively enhanced the transcriptional activity of the PV8 promoter. Biotic stress stimuli induced PV8 promoter activity by ~1.5 times. We also established the possible pathogen-elicitor function of AtWRKY71 and NtabWRKY71 TFs. Altogether, this study elucidates the interplay between TFs, biotic stress and caulimoviral promoter function. Copyright © 2018 Elsevier B.V. All rights reserved.

Synthesis and characterization of vanadiumoxidecatalysts supported on copper orthophosphates

NASA Astrophysics Data System (ADS)

Ouchabi, M.; Baalala, M.; Elaissi, A.; Loulidi, I.; Bensitel, M.

2017-03-01

Synthesis of a pure copper orthophosphate (CuP) prepared by Coprecipitation, and CuP modified by impregnation of vanadium (2-12 wt % of V2O5) have been carried out. The solids obtained were investigated as synthesized or after calcination by various physico-chemical techniques such as X-Ray Diffraction (XRD), Infrared Spectroscopy (IR), Thermogravimetric analysis (TGA), and differential thermal analysis (DTA). The results revealed that the solids V/CuP consisted of copper orthophosphate Cu3(PO4)2 as major phases, together with V2O5 as minor phase. The diffraction lines of V2O5 increase by increasing the vanadium content.

Recovery of high speed memory scanning after transient global amnesia: a case report.

PubMed

Okura, M; Tomotake, M; Mori, K; Ikuta, T

1996-12-01

We described the case of a 59 year old female with transient global amnesia (TGA) who had been examined neuropsychologically using Sternberg's paradigm and a random number generation (RNG) task on the following day, 1 week and 4 weeks after a TGA episode. The slope value of the linear function, a measure of cognitive memory scanning speed, decreased with time and showed a marked decrease 1 week after TGA, suggesting that the stage of serial and exhaustive scanning recovered within 1 week. The zero-intercept value, on the other hand, increased during 1 week but decreased 4 weeks later and was not related directly to recovery from TGA. The performance in RNG task improved 1 week later, but deteriorated 4 weeks after the episode. Such a change in RNG was in accordance with that of the zero-intercept value, predicting a relationship. It is concluded that the subclinical memory deficit, detected with these tasks, persisted longer than clinical recovery from TGA.

Pregnancy after atrial repair for transposition of the great arteries.

PubMed

Genoni, M; Jenni, R; Hoerstrup, S P; Vogt, P; Turina, M

1999-03-01

To investigate the risk of pregnancy in patients with transposition of the great arteries (TGA) who have undergone atrial repair. Retrospective analysis (1962-94) of 342 TGA patients who underwent atrial repair. Of 231 known late survivors, 48 were women over 18 years old who were interviewed about possible reproductive plans and previous pregnancies. As a control, comparison was made with data of 57 500 women (mean age 26 years) obtained from the Swiss Statistical Bank in Bern. Mean follow up was 13.7 years; 66% remained asymptomatic, 29% had mild to moderate cardiac symptoms, and 5% suffered from severe cardiac symptoms (New York Heart Association grade III-IV). Thirty six of the 48 women wished to bear children and, to date, there have been 10 live births, two spontaneous first trimester abortions, and one induced abortion at 16 weeks. During pregnancy there was one case of cardiac deterioration and two cases of pneumonia. There was no evidence of congenital heart disease in the children. In this relatively small series the completion of pregnancy in women with TGA who had undergone atrial repair and who had normal functional cardiac status was uncomplicated

Time of flight MR angiography assessment casts doubt on the association between transient global amnesia and intracranial jugular venous reflux.

PubMed

Kang, Yeonah; Kim, Eunhee; Kim, Jae Hyoung; Choi, Byung Se; Jung, Cheolkyu; Bae, Yun Jung; Lee, Kyung Mi; Lee, Dong Hoon

2015-03-01

Evidence of intracranial venous reflux flow due to jugular venous reflux (JVR) on time of flight (TOF) MR angiography (MRA) is thought to be highly associated with transient global amnesia (TGA)-evidence that supports the venous congestion theory of TGA pathophysiology. However, recent studies indicate that intracranial JVR on TOF MRA is occasionally observed in normal elderly. Therefore, the purpose of this study was to compare the prevalence of intracranial JVR on TOF MRA in patients with TGA and two control groups. Three age- and sex-matched groups of subjects that received MRI and MRA were enrolled. The groups comprised 167 patients with TGA, 167 visitors to the emergency room (ER) and 167 visitors to a health promotion centre (HPC). Intracranial JVR was defined as abnormal venous signals in the inferior petrosal, sigmoid and/or transverse sinuses on TOF MRA. The prevalence of intracranial JVR was assessed across the three groups. Intracranial JVR was seen in seven (4.2 %) TGA patients, eight (4.8 %) ER visitors and three (1.8 %) HPC visitors, respectively. No statistically significant differences were observed among the three groups. TGA patients showed a low prevalence of intracranial JVR on TOF MRA, and no statistical differences were found in comparison with control groups.

Is It Necessary to Dry Primary Standards before Analysis?

ERIC Educational Resources Information Center

Spraggins, Jeffrey M., II; Williams, Theodore R.

2005-01-01

The thermal gravimetric analysis (TGA) data suggests that the quantity of volatile components in primary standards is less than 1% of the initial weight and differential scanning calorimetry (DSC) data shows that water present in the same chemicals is below the limit of detection of the instrumentation. This suggests that the 1-2 hour drying…

Probing the oxidation kinetics of small permalloy particles

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

Dong, Xiaolei; Song, Xiao; Yin, Shiliu

2017-02-15

The oxidation of permalloys is important to apply in a wide range. The oxidation and diffusion mechanisms of small permalloy particles with different Fe content are studied by using thermal gravimetric analysis (TGA) and microstructure characterizations. Fe{sub 2}O{sub 3}/(Ni, Fe){sub 3}O{sub 4} plays a key role in the morphology evolution and diffusion mechanisms of small NiFe particles upon oxidation. The activation energies of grain boundary diffusion for the NiFe alloys increase from 141 kJ/mol to 208 kJ/mol as the Fe content increases from 0 to ~50 wt%. We have developed a diffusion process resolved temperature programed oxidation (PR-TPO) analysis method.more » Three diffusion mechanisms have been recognized by using this method: In addition to the grain boundary diffusion and lattice diffusion, our TGA analysis suggests that the phase conversion from Fe{sub 2}O{sub 3} to (Ni, Fe){sub 3}O{sub 4} induces diffusion change and affects the diffusion process at the intermediate temperature. Relevant oxidation kinetics and diffusion mechanisms are discussed. - Graphical abstract: The oxidation mechanisms of small Permalloy particles with different Fe content is studied by using thermal gravimetric analysis (TGA) and microstructure characterizations. The activation energies of grain boundary diffusion for the NiFe alloys increases from 140 kJ/mol to 208 kJ/mol as the Fe content increases from 0 to 50 wt% as determined by TGA. We have developed a diffusion process resolved temperature programed oxidation (DPR-TPO) analysis method, and three diffusion mechanisms have been recognized by using this method: In addition to the well-known grain boundary diffusion and lattice diffusion, we found that the phase conversion from Fe{sub 2}O{sub 3} to (Ni, Fe){sub 3}O{sub 4} will induce diffusion changes and affect the diffusion process at the intermediate temperature. The diffusion processes can be characterized by the corresponding characteristic peak temperatures in temperature programmed oxidation (TPO) analysis. This work not only give insight knowledge about the oxidation and diffusion processes of small permalloy particles, but also, provides a useful tool for analyzing solid-gas reactions of other materials. - Highlights: • The oxidation kinetics of small NiFe particles were studied by using thermoanalysis. • Grain boundary, lattice, and phase conversion induced diffusions were recognized. • The activation energy of oxidation increases with the Fe content in the alloy. • Each diffusion process corresponds to a characteristic temperature in TPO analysis. • NiFe alloys with ~5–10 wt% Fe content have the lowest oxidation rates.« less

Chemicl-looping combustion of coal with metal oxide oxygen carriers

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

Siriwardane, R.; Tian, H.; Richards, G.

2009-01-01

The combustion and reoxidation properties of direct coal chemical-looping combustion (CLC) over CuO, Fe2O3, Co3O4, NiO, and Mn2O3 were investigated using thermogravimetric analysis (TGA) and bench-scale fixed-bed flow reactor studies. When coal is heated in either nitrogen or carbon dioxide (CO2), 50% of weight loss was observed because of partial pyrolysis, consistent with the proximate analysis. Among various metal oxides evaluated, CuO showed the best reaction properties: CuO can initiate the reduction reaction as low as 500 °C and complete the full combustion at 700 °C. In addition, the reduced copper can be fully reoxidized by air at 700 °C.more » The combustion products formed during the CLC reaction of the coal/metal oxide mixture are CO2 and water, while no carbon monoxide was observed. Multicycle TGA tests and bench-scale fixed-bed flow reactor tests strongly supported the feasibility of CLC of coal by using CuO as an oxygen carrier. Scanning electron microscopy (SEM) images of solid reaction products indicated some changes in the surface morphology of a CuO-coal sample after reduction/oxidation reactions at 800 °C. However, significant surface sintering was not observed. The interactions of fly ash with metal oxides were investigated by X-ray diffraction and thermodynamic analysis. Overall, the results indicated that it is feasible to develop CLC with coal by metal oxides as oxygen carriers.« less

Growth and metabolic characteristics of oleaginous microalgal isolates from Nilgiri biosphere Reserve of India.

PubMed

Thangavel, Kalaiselvi; Radha Krishnan, Preethi; Nagaiah, Srimeena; Kuppusamy, Senthil; Chinnasamy, Senthil; Rajadorai, Jude Sudhagar; Nellaiappan Olaganathan, Gopal; Dananjeyan, Balachandar

2018-01-03

Renewable energy for sustainable development is a subject of a worldwide debate since continuous utilization of non-renewable energy sources has a drastic impact on the environment and economy; a search for alternative energy resources is indispensable. Microalgae are promising and potential alternate energy resources for biodiesel production. Thus, our efforts were focused on surveying the natural diversity of microalgae for the production of biodiesel. The present study aimed at identification, isolation, and characterization of oleaginous microalgae from shola forests of Nilgiri Biosphere Reserve (NBR), the biodiversity hot spot of India, where the microalgal diversity has not yet been systematically investigated. Overall the higher biomass yield, higher lipid accumulation and thermotolerance observed in the isolated microalgal strains have been found to be the desirable traits for the efficient biodiesel production. Species composition and diversity analysis yielded ten potential microalgal isolates belonging to Chlorophyceae and Cyanophyceae classes. The chlorophytes exhibited higher growth rate, maximum biomass yield, and higher lipid accumulation than Cyanophyceae. Among the chlorophytes, the best performing strains were identified and represented by Acutodesmus dissociatus (TGA1), Chlorella sp. (TGA2), Chlamydomonadales sp. (TGA3) and Hindakia tetrachotoma (PGA1). The Chlamydomonadales sp. recorded with the highest growth rate, lipid accumulation and biomass yield of 0.28 ± 0.03 day -1 (μ exp ), 29.7 ± 0.69% and 134.17 ± 16.87 mg L -1  day -1 , respectively. It was also found to grow well at various temperatures, viz., 25 °C, 35 °C, and 45 °C, indicating its suitability for open pond cultivation. The fatty acid methyl ester (FAME) analysis of stationary phase cultures of selected four algal strains by tandem mass spectrograph showed C16:0, C18:1 and C18:3 as dominant fatty acids suitable for biodiesel production. All the three strains except for Hindakia tetrachotoma (PGA1) recorded higher carbohydrate content and were considered as potential feed stocks for biodiesel production through hydrothermal liquefaction technology (HTL). In conclusion, the present investigation is a first systematic study on the microalgal diversity of soil and water samples from selected sites of NBR. The study resulted in isolation and characterization of ten potent oleaginous microalgae and found four cultures as promising feed stocks for biodiesel production. Of the four microalgae, Chlamydomonadales sp. (TGA3) was found to be significantly thermo-tolerant and can be considered as promising feedstock for biodiesel production.

LAB-SCALE DEMONSTRATION OF PLUTONIUM PURIFICATION BY ANION EXCHANGE, PLUTONIUM (IV) OXALATE PRECIPITATION, AND CALCINATION TO PLUTONIUM OXIDE TO SUPPORT THE MOX FEED MISSION

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

Crowder, M.; Pierce, R.

2012-08-22

H-Canyon and HB-Line are tasked with the production of PuO{sub 2} from a feed of plutonium metal. The PuO{sub 2} will provide feed material for the MOX Fuel Fabrication Facility. After dissolution of the Pu metal in H-Canyon, the solution will be transferred to HB-Line for purification by anion exchange. Subsequent unit operations include Pu(IV) oxalate precipitation, filtration and calcination to form PuO{sub 2}. This report details the results from SRNL anion exchange, precipitation, filtration, calcination, and characterization tests, as requested by HB-Line1 and described in the task plan. This study involved an 80-g batch of Pu and employed testmore » conditions prototypical of HB-Line conditions, wherever feasible. In addition, this study integrated lessons learned from earlier anion exchange and precipitation and calcination studies. H-Area Engineering selected direct strike Pu(IV) oxalate precipitation to produce a more dense PuO{sub 2} product than expected from Pu(III) oxalate precipitation. One benefit of the Pu(IV) approach is that it eliminates the need for reduction by ascorbic acid. The proposed HB-Line precipitation process involves a digestion time of 5 minutes after the time (44 min) required for oxalic acid addition. These were the conditions during HB-line production of neptunium oxide (NpO{sub 2}). In addition, a series of small Pu(IV) oxalate precipitation tests with different digestion times were conducted to better understand the effect of digestion time on particle size, filtration efficiency and other factors. To test the recommended process conditions, researchers performed two nearly-identical larger-scale precipitation and calcination tests. The calcined batches of PuO{sub 2} were characterized for density, specific surface area (SSA), particle size, moisture content, and impurities. Because the 3013 Standard requires that the calcination (or stabilization) process eliminate organics, characterization of PuO{sub 2} batches monitored the presence of oxalate by thermogravimetric analysis-mass spectrometry (TGA-MS). To use the TGA-MS for carbon or oxalate content, some method development will be required. However, the TGA-MS is already used for moisture measurements. Therefore, SRNL initiated method development for the TGA-MS to allow quantification of oxalate or total carbon. That work continues at this time and is not yet ready for use in this study. However, the collected test data can be reviewed later as those analysis tools are available.« less

SU-D-9A-02: Relative Effects of Threshold Choice and Spatial Resolution Modeling On SUV and Volume Quantification in F18-FDG PET Imaging of Anal Cancer Patients

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

Zhao, F; Shandong Cancer Hospital and Insititute, Jinan, Shandong; Bowsher, J

2014-06-01

Purpose: PET imaging with F18-FDG is utilized for treatment planning, treatment assessment, and prognosis. A region of interest (ROI) encompassing the tumor may be determined on the PET image, often by a threshold T on the PET standard uptake values (SUVs). Several studies have shown prognostic value for relevant ROI properties including maximum SUV value (SUVmax), metabolic tumor volume (MTV), and total glycolytic activity (TGA). The choice of threshold T may affect mean SUV value (SUVmean), MTV, and TGA. Recently spatial resolution modeling (SRM) has been introduced on many PET systems. SRM may also affect these ROI properties. The purposemore » of this work is to investigate the relative influence of SRM and threshold choice T on SUVmean, MTV, TGA, and SUVmax. Methods: For 9 anal cancer patients, 18F-FDG PET scans were performed prior to treatment. PET images were reconstructed by 2 iterations of Ordered Subsets Expectation Maximization (OSEM), with and without SRM. ROI contours were generated by 5 different SUV threshold values T: 2.5, 3.0, 30%, 40%, and 50% of SUVmax. Paired-samples t tests were used to compare SUVmean, MTV, and TGA (a) for SRM on versus off and (b) between each pair of threshold values T. SUVmax was also compared for SRM on versus off. Results: For almost all (57/60) comparisons of 2 different threshold values, SUVmean, MTV, and TGA showed statistically significant variation. For comparison of SRM on versus off, there were no statistically significant changes in SUVmax and TGA, but there were statistically significant changes in MTV for T=2.5 and T=3.0 and in SUVmean for all T. Conclusion: The near-universal statistical significance of threshold choice T suggests that, regarding harmonization across sites, threshold choice may be a greater concern than choice of SRM. However, broader study is warranted, e.g. other iterations of OSEM should be considered.« less

Antibacterial potential of rutin conjugated with thioglycolic acid capped cadmium telluride quantum dots (TGA-CdTe QDs)

NASA Astrophysics Data System (ADS)

Ananth, Devanesan Arul; Rameshkumar, Angappan; Jeyadevi, Ramachandran; Jagadeeswari, Sivanadanam; Nagarajan, Natarajan; Renganathan, Rajalingam; Sivasudha, Thilagar

2015-03-01

Quantum dots not only act as nanocarrier but also act as stable and resistant natural fluorescent bio markers used in various in vitro and in vivo photolabelling and biological applications. In this study, the antimicrobial potential of TGA-CdTe QDs and commercial phenolics (rutin and caffeine) were investigated against Escherichiacoli. UV absorbance and fluorescence quenching study of TGA-CdTe QDs with rutin and caffeine complex was measured by spectroscopic technique. QDs-rutin conjugate exhibited excellent quenching property due to the -OH groups present in the rutin structure. But the same time caffeine has not conjugated with QDs because of lacking of -OH group in its structure. Photolabelling of E. coli with QDs-rutin and QDs-caffeine complex was analyzed by fluorescent microscopic method. Microbe E. coli cell membrane damage was assessed by atomic force (AFM) and confocal microscopy. Based on the results obtained, it is suggested that QDs-rutin conjugate enhance the antimicrobial activity more than the treatment with QDs, rutin and caffeine alone.

Using the thermal Gaussian approximation for the Boltzmann operator in semiclassical initial value time correlation functions.

PubMed

Liu, Jian; Miller, William H

2006-12-14

The thermal Gaussian approximation (TGA) recently developed by Frantsuzov et al. [Chem. Phys. Lett. 381, 117 (2003)] has been demonstrated to be a practical way for approximating the Boltzmann operator exp(-betaH) for multidimensional systems. In this paper the TGA is combined with semiclassical (SC) initial value representations (IVRs) for thermal time correlation functions. Specifically, it is used with the linearized SC-IVR (LSC-IVR, equivalent to the classical Wigner model), and the "forward-backward semiclassical dynamics" approximation developed by Shao and Makri [J. Phys. Chem. A 103, 7753 (1999); 103, 9749 (1999)]. Use of the TGA with both of these approximate SC-IVRs allows the oscillatory part of the IVR to be integrated out explicitly, providing an extremely simple result that is readily applicable to large molecular systems. Calculation of the force-force autocorrelation for a strongly anharmonic oscillator demonstrates its accuracy, and calculation of the velocity autocorrelation function (and thus the diffusion coefficient) of liquid neon demonstrates its applicability.

Pyrolytic characteristics of biomass acid hydrolysis residue rich in lignin.

PubMed

Huang, Yanqin; Wei, Zhiguo; Yin, Xiuli; Wu, Chuangzhi

2012-01-01

Pyrolytic characteristics of acid hydrolysis residue (AHR) of corncob and pinewood (CAHR, WAHR) were investigated using a thermo-gravimetric analyzer (TGA) and a self-designed pyrolysis apparatus. Gasification reactivity of CAHR char was then examined using TGA and X-ray diffractometer. Result of TGA showed that thermal degradation curves of AHR descended smoothly along with temperature increasing from 150 °C to 850 °C, while a "sharp mass loss stage" for original biomass feedstock (OBF) was observed. Char yield from AHR (42.64-30.35 wt.%) was found to be much greater than that from OBF (26.4-19.15 wt.%). In addition, gasification reactivity of CAHR char was lower than that of corncob char, and there was big difference in micro-crystallite structure. It was also found that CAHR char reactivity decreased with pyrolysis temperature, but increased with pyrolysis heating rate and gasification temperature at 850-950 °C. Furthermore, CAHR char reactivity performed better under steam atmosphere than under CO2 atmosphere. Copyright © 2011 Elsevier Ltd. All rights reserved.

Use of Several Thermal Analysis Techniques on a Hypalon Paint Coating for the Solid Rocket Booster (SRB) of the Space Shuttle

NASA Technical Reports Server (NTRS)

Wingard, Charles D.; Whitaker, Ann F. (Technical Monitor)

2000-01-01

White Hypalon paint is brush-applied as a moisture barrier coating over cork surfaces on each of the two Space Shuttle SRBs. Fine cracks have been observed in the Hypalon coating three times historically on laboratory witness panels, but never on flight hardware. Samples of the cracked and standard ("good") Hypalon were removed from witness panel cork surfaces, and were tested in 1998 by Thermogravimetric Analysis (TGA), TMA and Differential Scanning Calorimetry (DSC) thermal analysis techniques. The TGA data showed that at 700C, where only paint pigment solids remain, the cracked material had about 9 weight percent more material remaining than the standard material, probably indicating incomplete mixing of the paint before it was brush-applied to produce the cracked material. Use of the TMA film/fiber technique showed that the average modulus (stiffness) vs. temperature was about 3 to 6 times higher for the cracked material than for the standard material. The TMA data also showed that an increase in coating thickness for the cracked Hypalon was not a factor in the anomaly.

Intercalated chitosan/hydroxyapatite nanocomposites: Promising materials for bone tissue engineering applications.

PubMed

Nazeer, Muhammad Anwaar; Yilgör, Emel; Yilgör, Iskender

2017-11-01

Preparation and characterization of chitosan/hydroxyapatite (CS/HA) nanocomposites displaying an intercalated structure is reported. Hydroxyapatite was synthesized through sol-gel process. Formic acid was introduced as a new solvent to obtain stable dispersions of nano-sized HA particles in polymer solution. CS/HA dispersions with HA contents of 5, 10 and 20% by weight were prepared. Self-assembling of HA nanoparticles during the drying of the solvent cast films led to the formation of homogeneous CS/HA nanocomposites. Composite films were analyzed by scanning electron microscopy (SEM), atomic force microscopy (AFM), energy dispersive X-rays (EDX) analysis, Fourier transform infrared (FTIR) spectroscopy, X-rays diffraction (XRD) analysis and thermogravimetric analysis (TGA). SEM and AFM confirmed the presence of uniformly distributed HA nanoparticles on the chitosan matrix surface. XRD patterns and cross-sectional SEM images showed the formation of layered nanocomposites. Complete degradation of chitosan matrix in TGA experiments, led to the formation of nanoporous 3D scaffolds containing hydroxyapatite, β-tricalcium phosphate and calcium pyrophosphate. CS/HA composites can be considered as promising materials for bone tissue engineering applications. Copyright © 2017 Elsevier Ltd. All rights reserved.

Structural and Spectroscopic Studies of Sm3+/CdS Nanocrystallites in Sol-Gel TiO2-ZrO2 Matrix

NASA Astrophysics Data System (ADS)

Karthika, S.; Prathibha, Vasudevan; Ann, Mary K. A.; Viji, Vidyadharan; Biju, P. R.; Unnikrishnan, N. V.

2014-02-01

A sol-gel method was used to prepare titania-zirconia matrices doped with Sm3+/CdS nanocrystallites. The structural properties of the matrices were characterized using transmission electron microscopy (TEM), thermogravimetric analysis (TGA), differential thermal analysis (DTA), and Fourier-transform infrared spectroscopy studies. The thermal stability of the material was determined by TGA/DTA analysis. The absorption spectrum shows the characteristic peaks of the Sm3+ ions and the absorption peak corresponding to the CdS nanocrystallites. The optical bandgap and size of the CdS nanoparticles were calculated from the absorption spectrum. From TEM, the interplanar distance ( d) was estimated to be 3.533 Å, which matches with the (1 0 0) plane of bulk CdS. The measurements yield a nanocrystallite size of around 7.8 nm. The optical absorption and emission spectra confirmed the formation of CdS nanoparticles along with samarium ions in the titania-zirconia matrices. The fluorescence intensity of the samarium ions was found to be greatly enhanced by codoping with CdS nanocrystallites.

Structural and thermal properties of silk fibroin - Silver nanoparticles composite films

NASA Astrophysics Data System (ADS)

Shivananda, C. S.; Rao B, B. Lakshmeesha; Shetty, G. Rajesh; Sangappa, Y.

2018-05-01

In this work, silk fibroin-silver nanoparticles (SF-AgNPs) composite films have been prepared by simple solution casting method. The composite films were examined for structural and thermal properties using X-ray diffraction (XRD), thermogravimatric (TGA) and differential scanning calorimetry (DSC) analysis. The XRD results showed that with the introduction of AgNPs in the silk fibroin matrix the amorphous nature of the silk fibroin decreases with increasing nanoparticles concentration. The silk fibroin films possess good thermal stability with the presence of AgNPs.

Pyrolytic Characteristics and Kinetics of Phragmites australis

PubMed Central

Zhao, Hui; Yan, Huaxiao; Zhang, Congwang; Liu, Xiaodong; Xue, Yanhui; Qiao, Yingyun; Tian, Yuanyu; Qin, Song

2011-01-01

The pyrolytic kinetics of Phragmites australis was investigated using thermogravimetric analysis (TGA) method with linear temperature programming process under an inert atmosphere. Kinetic expressions for the degradation rate in devolatilization and combustion steps have been obtained for P. australis with Dollimore method. The values of apparent activation energy, the most probable mechanism functions, and the corresponding preexponential factor were determined. The results show that the model agrees well with the experimental data and provide useful information for the design of pyrolytic processing system using P. australis as feedstock to produce biofuel. PMID:22007256

Structural and thermal properties of γ - irradiated Bombyx mori silk fibroin films

NASA Astrophysics Data System (ADS)

Madhukumar, R.; Asha, S.; Sarojini, B. K.; Somashekar, R.; Rao, B. Lakshmeesha; Shivananda, C. S.; Harish, K. V.; Sangappa

2015-06-01

The gamma radiation-induced change in structural and thermal properties of Bombyx mori silk fibroin films were investigated and have been correlated with the applied radiation doses. Irradiation of samples were carried out in dry air at room temperature using Co-60 source, and radiation doses are in the range of 0 - 300 kGy. Structural and thermal properties of the irradiated silk films were studied using X-ray diffraction (XRD), Differential Scanning Calorimetry (DSC) and Thermogravimetric analysis (TGA) and compared with unirradiated sample. Interesting results are discussed in this report.

The use of novel biodegradable, optically active and nanostructured poly(amide-ester-imide) as a polymer matrix for preparation of modified ZnO based bionanocomposites

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

Abdolmaleki, Amir, E-mail: abdolmaleki@cc.iut.ac.ir; Nanotechnology and Advanced Materials Institute, Isfahan University of Technology, Isfahan 84156-83111, Islamic Republic of Iran; Mallakpour, Shadpour, E-mail: mallak@cc.iut.ac.ir

Highlights: Black-Right-Pointing-Pointer A novel biodegradable and nanostructured PAEI based on two amino acids, was synthesized. Black-Right-Pointing-Pointer ZnO nanoparticles were modified via two different silane coupling agents. Black-Right-Pointing-Pointer PAEI/modified ZnO BNCs were synthesized through ultrasound irradiation. Black-Right-Pointing-Pointer ZnO particles were dispersed homogeneously in PAEI matrix on nanoscale. Black-Right-Pointing-Pointer The effect of ZnO nanoparticles on the properties of synthesized polymer was examined. -- Abstract: A novel biodegradable and nanostructured poly(amide-ester-imide) (PAEI) based on two different amino acids, was synthesized via direct polycondensation of biodegradable N,N Prime -bis[2-(methyl-3-(4-hydroxyphenyl)propanoate)]isophthaldiamide and N,N Prime -(pyromellitoyl)-bis-L-phenylalanine diacid. The resulting polymer was characterized by FT-IR, {sup 1}H NMR,more » specific rotation, elemental analysis, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), X-ray diffraction (XRD) and field emission scanning electron microscopy (FE-SEM) analysis. The synthesized polymer showed good thermal stability with nano and sphere structure. Then PAEI/ZnO bionanocomposites (BNCs) were fabricated via interaction of pure PAEI and ZnO nanoparticles. The surface of ZnO was modified with two different silane coupling agents. PAEI/ZnO BNCs were studied and characterized by FT-IR, XRD, UV/vis, FE-SEM and TEM. The TEM and FE-SEM results indicated that the nanoparticles were dispersed homogeneously in PAEI matrix on nanoscale. Furthermore the effect of ZnO nanoparticle on the thermal stability of the polymer was investigated with TGA and DSC technique.« less

Antigastric parietal cell and antithyroid autoantibodies in patients with desquamative gingivitis.

PubMed

Chang, Julia Yu-Fong; Chiang, Chun-Pin; Wang, Yi-Ping; Wu, Yang-Che; Chen, Hsin-Ming; Sun, Andy

2017-04-01

Desquamative gingivitis (DG) is principally associated with erosive oral lichen planus (EOLP), mucous membrane pemphigoid (MMP), and pemphigus vulgaris (PV). Serum autoantibodies including antigastric parietal cell antibody (GPCA), antithyroglobulin antibody (TGA), and antithyroid microsomal antibody (TMA) were measured in 500 patients with DG, 287 EOLP without DG (EOLP/DG - ) patients, and 100 healthy control subjects. The 500 patients with DG were diagnosed as having EOLP in 455 (91%), PV in 40 (8%), and MMP in five (1%) patients. We found that 37.0%, 43.6%, and 42.6% of 500 patients with DG, 39.6%, 46.4%, and 45.1% of 455 EOLP with DG (EOLP/DG) patients, and 18.5%, 27.5%, and 30.3% of 287 EOLP/DG - patients had the presence of GPCA, TGA, and TMA in their sera, respectively. DG, EOLP/DG, and EOLP/DG - patients all had a significantly higher frequency of GPCA, TGA, or TMA positivity than healthy control subjects (all P-values < 0.001). Moreover, 455 EOLP/DG patients had a significantly higher frequency of GPCA, TGA, or TMA positivity than 287 EOLP/DG - patients (all P-values < 0.001). Of 210 TGA/TMA-positive patients with DG whose serum thyroid-stimulating hormone (TSH) levels were measured, 84.3%, 6.7%, and 9.0% patients had normal, lower, and higher serum TSH levels, respectively. We conclude that 73.4% DG, 77.1% EOLP/DG, and 47.4% EOLP/DG - patients may have GPCA/TGA/TMA positivity in their sera. Because part of GPCA-positive patients may develop pernicious anemia, autoimmune atrophic gastritis, and gastric carcinoma, and part of TGA/TMA-positive patients may have thyroid dysfunction, these patients should be referred to medical department for further management. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Catalytic thermal cracking of post-consumer waste plastics to fuels: Part 1 - Kinetics and optimization

USDA-ARS?s Scientific Manuscript database

Thermogravimetric analysis (TGA) was used to investigate thermal and catalytic pyrolysis of waste plastics such as prescription bottles (polypropylene/PP), high density polyethylene, landfill liners (polyethylene/PE), packing materials (polystyrene/PS), and foams (polyurethane/PU) into crude plastic...

Environmentally Benign Repair of Composites Using High Temperature Cyanate Ester Nanocomposites

DTIC Science & Technology

2010-10-01

temperature by magnetic stirring. Thermogravimetric analysis (TG) measurements were performed on a TG model Q50 (TA Instruments, Inc.) to determine the...standard 1259-85. These experiments were also compared with thermogravimetric analysis (TGA) in both dynamic heating and isothermal conditions. The...characterized with thermogravimetric analysis (TG) and Fourier transform infrared spectroscopy (FT-IR). For the TG, about 20 mg of sample was placed in

Analysis of the combustion and pyrolysis of dried sewage sludge by TGA and MS.

PubMed

Magdziarz, Aneta; Werle, Sebastian

2014-01-01

In this study, the combustion and pyrolysis processes of three sewage sludge were investigated. The sewage sludge came from three wastewater treatment plants. Proximate and ultimate analyses were performed. The thermal behaviour of studied sewage sludge was investigated by thermogravimetric analysis with mass spectrometry (TGA-MS). The samples were heated from ambient temperature to 800 °C at a constant rate 10 °C/min in air (combustion process) and argon flows (pyrolysis process). The thermal profiles presented in form of TG/DTG curves were comparable for studied sludges. All TG/DTG curves were divided into three stages. The main decomposition of sewage sludge during the combustion process took place in the range 180-580 °C with c.a. 70% mass loss. The pyrolysis process occurred in lower temperature but with less mass loss. The evolved gaseous products (H2, CH4, CO2, H2O) from the decomposition of sewage sludge were identified on-line. Copyright © 2013 Elsevier Ltd. All rights reserved.

Thermal stability and electrochemical properties of PVP-protected Ru nanoparticles synthesized at room temperature

NASA Astrophysics Data System (ADS)

Kumar, Manish; Devi, Pooja; Shivling, V. D.

2017-08-01

Stable ruthenium nanoparticles (RuNPs) have been synthesized by the chemical reduction of ruthenium trichloride trihydrate (RuCl3 · 3H2O) using sodium borohydride (NaBH4) as a reductant and polyvinylpyrrolidone (PVP) as a protecting agent in the aqueous medium at room temperature. The nanoparticles thus prepared were characterized by their morphology and structural analysis from transmission electron microscopy (TEM), X-ray powder diffraction (XRD), UV-vis spectroscopy, Fourier transformation infrared and thermogravimetric analysis (TGA) techniques. The TEM image suggested a homogeneous distribution of PVP-protected RuNPs having a small average diameter of 2-4 nm with a chain-like network structure. The XRD pattern also confirmed that a crystallite size is around 2 nm of PVP-protected RuNPs having a single broad peak. The thermal stability studied using TGA, indicated good stability and the electrochemical properties of these nanoparticles revealed that saturation current increases for PVP-protected RuNPs/GC.

Electrochemical performance of a thermally rearranged polybenzoxazole nanocomposite membrane as a separator for lithium-ion batteries at elevated temperature

NASA Astrophysics Data System (ADS)

Lee, Moon Joo; Hwang, Jun-Ki; Kim, Ji Hoon; Lim, Hyung-Seok; Sun, Yang-Kook; Suh, Kyung-Do; Lee, Young Moo

2016-02-01

Shape-tunable hydroxyl copolyimide (HPI) nanoparticles are fabricated by a re-precipitation method and are coated onto electrospun HPI membranes, followed by heat treatment to prepare thermally rearranged polybenzoxazole (TR-PBO) composite membranes. The morphology of HPI nanoparticles consisted of sphere and sea-squirt structures, which is controlled by changing the concentration of the stabilizer. The morphological characteristics of TR-PBO nanoparticles convert from HPI nanoparticles by heat treatment and their composite membranes is confirmed by scanning electron microscopy (SEM), transmission electron microscopy (TEM), infrared spectroscopy (ATR-IR), thermogravimetric analysis (TGA) analysis, and contact angle measurements. TGA and DSC measurements confirm the excellent thermal stability compared to Celgard, a commercial PP separator for lithium-ion batteries (LIBs). Further, TR-PBO nano-composite membranes used in coin-cell type LIBs as a separator show excellent high power density performance as compared to Celgard. This is due to the fact that sea-squirt structured nanoparticles have better electrochemical properties than sphere structured nanoparticles at high temperature.

Thermal degradation of Shredded Oil Palm Empty Fruit Bunches (SOPEFB) embedded with Cobalt catalyst by Thermogravimetric Analysis (TGA)

NASA Astrophysics Data System (ADS)

Alias, R.; Hamid, N. H.; Jaapar, J.; Musa, M.; Alwi, H.; Halim, K. H. Ku

2018-03-01

Thermal behavior and decomposition kinetics of shredded oil palm empty fruit bunches (SOPEFB) were investigated in this study by using thermogravimetric analysis (TGA). The SOPEFB were analyzed under conditions of temperature 30 °C to 900 °C with nitrogen gas flow at 50 ml/min. The SOPEFB were embedded with cobalt (II) nitrate solution with concentration 5%, 10%, 15% and 20%. The TG/DTG curves shows the degradation behavior of SOPEFB following with char production for each heating rate and each concentration of cobalt catalyst. Thermal degradation occurred in three phases, water drying phase, decomposition of hemicellulose and cellulose phase, and lignin decomposition phase. The kinetic equation with relevant parameters described the activation energy required for thermal degradation at the temperature regions of 200 °C to 350 °C. Activation energy (E) for different heating rate with SOPEFB embedded with different concentration of cobalt catalyst showing that the lowest E required was at SOPEFB with 20% concentration of cobalt catalyst..

Kinetics of (3-aminopropyl)triethoxylsilane (APTES) silanization of superparamagnetic iron oxide nanoparticles.

PubMed

Liu, Yue; Li, Yueming; Li, Xue-Mei; He, Tao

2013-12-10

Silanization of magnetic ironoxide nanoparticles with (3-aminopropyl)triethoxylsilane (APTES) is reported. The kinetics of silanization toward saturation was investigated using different solvents including water, water/ethanol (1/1), and toluene/methanol (1/1) at different reaction temperature with different APTES loading. The nanoparticles were characterized by Fourier transform infrared spectroscopy, vibrating sample magnetometry, transmission electron microscopy, and thermal gravimetric analysis (TGA). Grafting density data based on TGA were used for the kinetic modeling. It is shown that initial silanization takes place very fast but the progress toward saturation is very slow, and the mechanism may involve adsorption, chemical sorption, and chemical diffusion processes. The highest equilibrium grafting density of 301 mg/g was yielded when using toluene/methanol mixture as the solvent at a reaction temperature of 70 °C.

Analyses of expression and localization of two mammalian-type transglutaminases in Physarum polycephalum, an acellular slime mold.

PubMed

Wada, Fumitaka; Ogawa, Atsuko; Hanai, Yuko; Nakamura, Akio; Maki, Masatoshi; Hitomi, Kiyotaka

2004-11-01

Transglutaminase (TGase) is an enzyme that modifies proteins by crosslinking or polyamination. Physarum polycephalum, an acellular slime mold, is the evolutionally lowest organism that has a mammalian-type transglutaminase. We have cloned a cDNA for Physarum polycephalum TGase (PpTGB), homologous to a previously identified TGase (PpTGA), whose sequence is similar to that of mammalian TGases. PpTGB encodes a primary sequence identical to that of PpTGA except for 11 amino acid residues at the N-terminus. Reverse transcription-PCR and Western blotting analyses showed that both PpTGA and PpTGB are expressed in microplasmodia and macroplasmodia during their life cycle, except for in sporangia. For biochemical characterization, we carried out the ectopical expressions of PpTGA and PpTGB in Dictyostelium discoideum. Subcellular fractionation of these Dictyostelium cells showed that the expressed PpTGA, but not PpTGB, localizes to the membrane fraction. Furthermore, in Physarum, subcellular fractionation and immunostaining indicated specific localization at the plasma membrane in macroplasmodia, while the localization was entirely cytoplasmic in microplasmodia.

Chlorine in coal and its relationship with boiler corrosion. Technical report, 1 March--31 May 1994

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

Chou, M.I.M.; Lytle, J.M.; Ruch, R.R.

1994-09-01

Limited literature and use history data have suggested that some high-chlorine Illinois coals do not cause boiler corrosion while extensive data developed by the British correlate corrosion with chlorine content and other parameters related to the coal and boiler. The differences in corrosivity in coals may be due to the coal properties, to blending of coals, or to the boiler parameters in which they were burned. The goals of this study focus on coal properties. In this quarter, both destructive temperature-programmed Thermogravimetry with Fourier transform infrared (TGA-FTIR) and non-destructive X-ray absorption near-edge structure (XANES) techniques were used to examine themore » forms and the evolution characteristics of chlorine in coals. The TGA-FTIR results indicate that under oxidation condition, both British and Illinois coals release hydrogen chloride gas. Illinois coals release the gas at high temperature with maximum evolution temperature ranged between 210 and 280 C. The XANES results indicate that chlorine in coal exists in ionic forms including a solid salt form. The solid NaCl salt form, however, is observed only in some of the British coals and none of the Illinois coals. These results combined with TGA-FTIR results suggest that the chlorine ions in Illinois coals are different from the chlorine ions in British coals.« less

Transient global amnesia: current perspectives

PubMed Central

Spiegel, David R; Smith, Justin; Wade, Ryan R; Cherukuru, Nithya; Ursani, Aneel; Dobruskina, Yuliya; Crist, Taylor; Busch, Robert F; Dhanani, Rahim M; Dreyer, Nicholas

2017-01-01

Transient global amnesia (TGA) is a clinical syndrome characterized by the sudden onset of an extraordinarily large reduction of anterograde and a somewhat milder reduction of retrograde episodic long-term memory. Additionally, executive functions are described as diminished. Although it is suggested that various factors, such as migraine, focal ischemia, venous flow abnormalities, and epileptic phenomena, are involved in the pathophysiology and differential diagnosis of TGA, the factors triggering the emergence of these lesions are still elusive. Recent data suggest that the vulnerability of CA1 neurons to metabolic stress plays a pivotal part in the pathophysiological cascade, leading to an impairment of hippocampal function during TGA. In this review, we discuss clinical aspects, new imaging findings, and recent clinical–epidemiological data with regard to the phenotype, functional anatomy, and putative cellular mechanisms of TGA. PMID:29123402

Mere exposure effect can be elicited in transient global amnesia.

PubMed

Marin-Garcia, Eugenia; Ruiz-Vargas, Jose M; Kapur, Narinder

2013-01-01

Transient global amnesia (TGA) is one of the most severe forms of anterograde amnesia seen in clinical practice, yet patients may show evidence of spared learning during the amnesic episode. The scope of spared learning in such a severe form of amnesia remains uncertain, and it is also unclear whether findings from single-case studies hold up in group studies of TGA patients. In this group study, we found evidence that extended the domain of spared learning in TGA to include the mere exposure effect, whereby enhanced preference is primed by prior exposure to stimuli. We demonstrate this effect during an acute episode in a group of TGA patients, where they showed enhanced preference for previously exposed faces, despite markedly impaired performance on standard anterograde memory tests.

Predicting functional capacity in patients with a systemic right ventricle: subjective patient self-assessment is better than B-type natriuretic peptide levels and right ventricular systolic function.

PubMed

Book, Wendy; McConnell, Michael; Oster, Matthew; Lyle, Teresa; Kogon, Brian

2013-01-01

Many adults with transposition of the great arteries have an anatomic right ventricle functioning as the systemic ventricle and are known to develop congestive heart failure, premature cardiac death, and need for cardiac transplantation. Predictors of poor clinical outcome and functional status in patients with left ventricular failure do not always apply to these patients. We aimed to identify predictors of poor functional status in those patients with a systemic right ventricle. We performed a prospective study of 51 adults with transposition of the great arteries and systemic right ventricles. Demographic, clinical, laboratory, and imaging data were collected, and patients completed a Minnesota Living with Heart Failure Questionnaire (MLHFQ). Comparisons were made between those patients with d-type transposition of the great arteries (dTGA) who have undergone prior atrial switch and those with congenitally corrected transposition (ccTGA). A correlation analysis was performed to identify predictors of poor functional status, as determined by a 6-minute walk distance test. Median age was 30 years (range 19-65). Median B-type natriuretic peptide was 48 pg/mL (range 16-406). There were 27 patients (53%) with moderate-severe right ventricular dysfunction and 10 (20%) with moderate-severe tricuspid valve regurgitation. The median MLHFQ score was 9 (range 0-78) and 6-minute walk test was 510 m (range 231-703). Forty-one patients had a diagnosis of dTGA atrial switch and 11 patients had ccTGA. Patients with ccTGA were significantly older (40 vs. 28 years, P =.004) and had more tricuspid valve regurgitation (P =.02). Despite this, their MLHFQ scores were significantly lower (2.5 vs. 17, P =.04) and they walked further (635 vs. 504 m, P =.02). Predictors of a short 6-minute walk distance included short stature (P =.009) and dTGA (P =.002). The patient's self-assessment of poor health, as measured by an increased New York Heart Association class (P =.003) and a decreased MLHFQ score (P >.0001) also correlated. B-type natriuretic peptide levels, right ventricular dysfunction, severity of tricuspid valve regurgitation, need for pacemaker, and clinical signs of heart failure did not correlate with exercise tolerance. Traditional parameters used to predict outcomes in patients with left ventricular failure are not predictive in patients with a systemic right ventricle. Instead, patient's self-assessment of functional status did correlate with objective functional status. © 2013 Wiley Periodicals, Inc.

Cardiovascular response to exercise training in the systemic right ventricle of adults with transposition of the great arteries

PubMed Central

Shafer, K M; Janssen, L; Carrick-Ranson, G; Rahmani, S; Palmer, D; Fujimoto, N; Livingston, S; Matulevicius, S A; Forbess, L W; Brickner, B; Levine, B D

2015-01-01

We aimed to assess the haemodynamic effects of exercise training in transposition of the great arteries (TGA) patients with systemic right ventricles (SRVs). TGA patients have limited exercise tolerance and early mortality due to systemic (right) ventricular failure. Whether exercise training enhances or injures the SRV is unclear. Fourteen asymptomatic patients (34 ± 10 years) with TGA and SRV were enrolled in a 12 week exercise training programme (moderate and high-intensity workouts). Controls were matched on age, gender, BMI and physical activity. Exercise testing pre- and post- training included: (a) submaximal and peak; (b) prolonged (60 min) submaximal endurance and (c) high-intensity intervals. Oxygen uptake (; Douglas bag technique), cardiac output (, foreign-gas rebreathing), ventricular function (echocardiography and cardiac MRI) and serum biomarkers were assessed. TGA patients had lower peak , , and stroke volume (SV), a blunted / slope, and diminished SV response to exercise (SV increase from rest: TGA = 15.2%, controls = 68.9%, P < 0.001) compared with controls. After training, TGA patients increased peak by 6 ± 8.5%, similar to controls (interaction P = 0.24). The magnitude of SV reserve on initial testing correlated with training response (r = 0.58, P = 0.047), though overall, no change in peak was observed. High-sensitivity troponin T (hs-TnT) and N-terminal prohormone of brain naturetic peptide (NT pro-BNP) were low and did not change with acute exercise or after training. Our data show that TGA patients with SRVs in this study safely participated in exercise training and improved peak . Neither prolonged submaximal exercise, nor high-intensity intervals, nor short-term exercise training seem to injure the systemic right ventricle. Key Points Patients with transposition of the great arteries (TGA) and systemic right ventricles have premature congestive heart failure; there is also a growing concern that athletes who perform extraordinary endurance exercise may injure the right ventricle. Therefore we felt it essential to determine whether exercise training might injure a systemic right ventricle which is loaded with every heartbeat. Previous studies have shown that short term exercise training is feasible in TGA patients, but its effect on ventricular function is unclear. We demonstrate that systemic right ventricular function is preserved (and may be improved) in TGA patients with exercise training programmes that are typical of recreational and sports participation, with no evidence of injury on biomarker assessment. Stroke volume reserve during exercise correlates with exercise training response in our TGA patients, identifying this as a marker of a systemic right ventricle (SRV) that may most tolerate (and possibly even be improved by) exercise training. PMID:25809342

Thermal degradation of sucralose: a combination of analytical methods to determine stability and chlorinated byproducts

NASA Astrophysics Data System (ADS)

de Oliveira, Diogo N.; de Menezes, Maico; Catharino, Rodrigo R.

2015-04-01

In the late years, much attention has been brought to the scientific community regarding the safety of sucralose and its industrial applications. Although it is the most used artificial sweetener in foods and pharmaceuticals, many questions still arise on its potential to form chlorinated byproducts in high temperatures, as demonstrated by several recent studies. In the present contribution, we use a combination of differential scanning calorimetry and thermogravimetric analysis coupled with infrared spectroscopy (DSC/TGA/IR), Hot-stage microscopy (HSM) and high-resolution mass spectrometry (HRMS) on samples submitted to water bath at mild temperatures to evaluate a broad spectrum of hazardous compounds formed in the degradation of this product. TGA/IR has revealed that there is effective decomposition in form of CO2 along with the formation of hydrogen chloride and other minor compounds. HSM results have provided accurate information, where the melting of the crystals was observed, followed by decomposition. Chlorinated derivatives, including polychlorinated aromatic hydrocarbons (PCAHs) were also confirmed by HRMS. These findings not only corroborate the suspected instability of sucralose to high temperatures, but also indicate that even exposed to mild conditions the formation of hazardous polychlorinated compounds is observed.

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

Wang, Biao; Zhou, Keqing; Jiang, Saihua

Highlights: • Layered zinc sulfide (LZnS) was synthesized successfully via hydrothermal method. • We prepare PMMA/LZnS nanocomposites by in situ bulk polymerization of MMA. • PMMA/LZnS nanocomposites were investigated by TGA, DSC, MCC, UV–vis and PL test. • The thermal stability, flame retardant and optical properties of PMMA are improved. - Abstract: Layered zinc sulfide (LZnS) was synthesized successfully via hydrothermal method and poly(methyl methacrylate) (PMMA)/layered zinc sulfide nanocomposites were obtained by in situ bulk polymerization of methyl methacrylate (MMA). X-ray diffraction (XRD) and transmission electron microscopy (TEM) were used to characterize the as-synthesized layered zinc sulfide and PMMA/layered zincmore » sulfide nanocomposites. Microscale combustion calorimeter (MCC), differential scanning calorimeter (DSC) and thermogravimetric analysis (TGA) were used to test the thermal properties of the composites. Ultraviolet visible (UV–vis) transmittance spectra and photoluminence (PL) spectra were obtained to investigate the optical properties of the composites. From the results, the thermal degradation temperature is increased by 20–50 °C, the peak of heat release rate (pHRR) and total heat release (THR) are both decreased by above 30%, and the photoluminence intensity is enhanced with the increasing loading of layered zinc sulfide.« less

Synthesis of Gold Nanoparticles Using Leaf Extract of Ziziphus zizyphus and their Antimicrobial Activity

PubMed Central

Akkam, Yazan; Al-Batayneh, Khalid M.; Abo Alrob, Osama; Alkilany, Alaaldin M.; Benamara, Mourad

2018-01-01

(1) Background: There is a growing need for the development of new methods for the synthesis of nanoparticles. The interest in such particles has raised concerns about the environmental safety of their production methods; (2) Objectives: The current methods of nanoparticle production are often expensive and employ chemicals that are potentially harmful to the environment, which calls for the development of “greener” protocols. Herein we describe the synthesis of gold nanoparticles (AuNPs) using plant extracts, which offers an alternative, efficient, inexpensive, and environmentally friendly method to produce well-defined geometries of nanoparticles; (3) Methods: The phytochemicals present in the aqueous leaf extract acted as an effective reducing agent. The generated AuNPs were characterized by Transmission electron microscopy (TEM), Scanning electron microscope (SEM), and Atomic Force microscopy (AFM), X-ray diffraction (XRD), UV-visible spectroscopy, energy dispersive X-ray (EDX), and thermogravimetric analyses (TGA); (4) Results and Conclusions: The prepared nanoparticles were found to be biocompatible and exhibited no antimicrobial or antifungal effect, deeming the particles safe for various applications in nanomedicine. TGA analysis revealed that biomolecules, which were present in the plant extract, capped the nanoparticles and acted as stabilizing agents. PMID:29562669

Evaluation of moisture barrier coatings on carbon-phenolic SRM nozzle materials

NASA Technical Reports Server (NTRS)

Mcnutt, Ronald C.

1986-01-01

The carbon-phenolic composite ablative material used on the Solid Rocket Motor (SRM) nozzle is known to absorb moisture from the atmosphere. This could cause problems such as pocketing during firing. Several moisture barrier coatings were tested on the SRM nozzle material. Data are presented for six of the 12 coatings to be tested. The data were obtained from immersion of coated samples in an environmental chamber at 100 F and 100% relative humidity and by using a modified TGA (thermal gravimetric analysis) technique. The TGA technique involved allowing wet nitrogen (25 C, 80% relative humidity) to flow across a small sample at about 65 cu cm per minute while continually monitoring the weight increase. These preliminary results show Kel-F-800, a material supplied by 3M Corporation to be the better moisture barrier. A second task was to collect data on the relative absorption of water and kerosene into the carbon-phenolic SRM nozzle material. These data indicate that water absorbs into the nozzle material to a much greater extent than kerosene. Thus kerosene is the more likely solvent in which to make specific gravity measurements on the SRM nozzle material.

Thermal degradation of sucralose: a combination of analytical methods to determine stability and chlorinated byproducts.

PubMed

de Oliveira, Diogo N; de Menezes, Maico; Catharino, Rodrigo R

2015-04-15

In the late years, much attention has been brought to the scientific community regarding the safety of sucralose and its industrial applications. Although it is the most used artificial sweetener in foods and pharmaceuticals, many questions still arise on its potential to form chlorinated byproducts in high temperatures, as demonstrated by several recent studies. In the present contribution, we use a combination of differential scanning calorimetry and thermogravimetric analysis coupled with infrared spectroscopy (DSC/TGA/IR), Hot-stage microscopy (HSM) and high-resolution mass spectrometry (HRMS) on samples submitted to water bath at mild temperatures to evaluate a broad spectrum of hazardous compounds formed in the degradation of this product. TGA/IR has revealed that there is effective decomposition in form of CO2 along with the formation of hydrogen chloride and other minor compounds. HSM results have provided accurate information, where the melting of the crystals was observed, followed by decomposition. Chlorinated derivatives, including polychlorinated aromatic hydrocarbons (PCAHs) were also confirmed by HRMS. These findings not only corroborate the suspected instability of sucralose to high temperatures, but also indicate that even exposed to mild conditions the formation of hazardous polychlorinated compounds is observed.

Thermal degradation of sucralose: a combination of analytical methods to determine stability and chlorinated byproducts

PubMed Central

de Oliveira, Diogo N.; de Menezes, Maico; Catharino, Rodrigo R.

2015-01-01

In the late years, much attention has been brought to the scientific community regarding the safety of sucralose and its industrial applications. Although it is the most used artificial sweetener in foods and pharmaceuticals, many questions still arise on its potential to form chlorinated byproducts in high temperatures, as demonstrated by several recent studies. In the present contribution, we use a combination of differential scanning calorimetry and thermogravimetric analysis coupled with infrared spectroscopy (DSC/TGA/IR), Hot-stage microscopy (HSM) and high-resolution mass spectrometry (HRMS) on samples submitted to water bath at mild temperatures to evaluate a broad spectrum of hazardous compounds formed in the degradation of this product. TGA/IR has revealed that there is effective decomposition in form of CO2 along with the formation of hydrogen chloride and other minor compounds. HSM results have provided accurate information, where the melting of the crystals was observed, followed by decomposition. Chlorinated derivatives, including polychlorinated aromatic hydrocarbons (PCAHs) were also confirmed by HRMS. These findings not only corroborate the suspected instability of sucralose to high temperatures, but also indicate that even exposed to mild conditions the formation of hazardous polychlorinated compounds is observed. PMID:25873245

Generation of Trichoderma atroviride mutants with constitutively activated G protein signaling by using geneticin resistance as selection marker.

PubMed

Gruber, Sabine; Omann, Markus; Rodrìguez, Carolina Escobar; Radebner, Theresa; Zeilinger, Susanne

2012-11-17

Species of the fungal genus Trichoderma are important industrial producers of cellulases and hemicellulases, but also widely used as biocontrol agents (BCAs) in agriculture. In the latter function Trichoderma species stimulate plant growth, induce plant defense and directly antagonize plant pathogenic fungi through their mycoparasitic capabilities. The recent release of the genome sequences of four mycoparasitic Trichoderma species now forms the basis for large-scale genetic manipulations of these important BCAs. Thus far, only a limited number of dominant selection markers, including Hygromycin B resistance (hph) and the acetamidase-encoding amdS gene, have been available for transformation of Trichoderma spp. For more extensive functional genomics studies the utilization of additional dominant markers will be essential. We established the Escherichia coli neomycin phosphotransferase II-encoding nptII gene as a novel selectable marker for the transformation of Trichoderma atroviride conferring geneticin resistance. The nptII marker cassette was stably integrated into the fungal genome and transformants exhibited unaltered phenotypes compared to the wild-type. Co-transformation of T. atroviride with nptII and a constitutively activated version of the Gα subunit-encoding tga3 gene (tga3Q207L) resulted in a high number of mitotically stable, geneticin-resistant transformants. Further analyses revealed a co-transformation frequency of 68% with 15 transformants having additionally integrated tga3Q207L into their genome. Constitutive activation of the Tga3-mediated signaling pathway resulted in increased vegetative growth and an enhanced ability to antagonize plant pathogenic host fungi. The neomycin phosphotransferase II-encoding nptII gene from Escherichia coli proved to be a valuable tool for conferring geneticin resistance to the filamentous fungus T. atroviride thereby contributing to an enhanced genetic tractability of these important BCAs.

Bentonite modification with pillarization method using metal stannum

NASA Astrophysics Data System (ADS)

Widjaya, Robert R.; Juwono, Ariadne L.; Rinaldi, Nino

2017-11-01

Clay minerals have received considerable attention in the last years because of their environmental compatibility, low cost, high selectivity, and operational simplicity. Although clays are very useful for many application in the field of catalysis, they have main disadvantage: their lack of pore volume and spesific surface area. Porosity and stability of these materials are improved by pillaring the clay layers with SnCl4, which leads to materials known as pillared clays (PILC). This research aims were to characterize the Bentonite and Sn-Bentonite as catalysts for cracking and oligomerization. The Sn-Bentonite was prepared by pillarization method with a variation in metal ratio of 5 mmol dan 10 mmol.gr-1 of bentonit. The catalyst characterized by X-ray Diffraction, X-ray Fluorescence, Fourier Transform Infra Red, Brunauer Emmett Teller, Thermogravimetric Analysis. The results showed that the Sn-Bentonite catalyst had large basal spacing and good porous structure, and the specific surface areas increased. XRF detected the Sn in the Bentonite and TGA results showed the ability Sn-Bentonite in receiving heat. FTIR test showed two type of acidity, broansted and lewis acid. The characterized results indicated that Sn-Bentonite with metal ratio 5 mmol.gr-1 better than Sn-Bentonite with metal ratio 10 mmol.gr-1, in which there was a significant increase the basal spacings, specific surface area, and pore volume. The TGA results for Sn-Bentonite appeared to be more thermally stable than Bentonite.

Characterization of Nanocomposites by Thermal Analysis

PubMed Central

Corcione, Carola Esposito; Frigione, Mariaenrica

2012-01-01

In materials research, the development of polymer nanocomposites (PN) is rapidly emerging as a multidisciplinary research field with results that could broaden the applications of polymers to many different industries. PN are polymer matrices (thermoplastics, thermosets or elastomers) that have been reinforced with small quantities of nano-sized particles, preferably characterized by high aspect ratios, such as layered silicates and carbon nanotubes. Thermal analysis (TA) is a useful tool to investigate a wide variety of properties of polymers and it can be also applied to PN in order to gain further insight into their structure. This review illustrates the versatile applications of TA methods in the emerging field of polymer nanomaterial research, presenting some examples of applications of differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), dynamic mechanical thermal analysis (DMTA) and thermal mechanical analysis (TMA) for the characterization of nanocomposite materials.

Electron-Beam Irradiation Effect on Thermal and Mechanical Properties of Nylon-6 Nanocomposite Fibers Infused with Diamond and Diamond Coated Carbon Nanotubes

NASA Astrophysics Data System (ADS)

Imam, Muhammad A.; Jeelani, Shaik; Rangari, Vijaya K.; Gome, Michelle G.; Moura, Esperidiana. A. B.

2016-02-01

Nylon-6 is an engineering plastic with excellent properties and processability, which are essential in several industrial applications. The addition of filler such as diamond (DN) and diamond coated carbon nanotubes (CNTs) to form molded composites may increase the range of Nylon-6 applications due to the resulting increase in strength. The effects of electron-beam irradiation on these thermoplastic nanocomposites are either increase in the cross-linking or causes chain scission. In this study, DN-coated CNTs were synthesized using the sonochemical technique in the presence of cationic surfactant cetyltrimethyl ammonium bromide (CTAB). The DN-coated CNTs nanoparticles and diamond nanoparticles were then introduced into Nylon-6 polymer through a melt extrusion process to form nanocomposite fibers. They were further tested for their mechanical (Tensile) and thermal properties (thermogravimetric analysis (TGA), differential scanning calorimetry (DSC)). These composites were further exposed to the electron-beam (160kGy, 132kGy and 99kGy) irradiation using a 1.5MeV electron-beam accelerator, at room temperature, in the presence of air and tested for their thermal and mechanical properties. The best ultimate tensile strength was found to be 690MPa and 864MPa irradiated at 132 for DN/CNTs/Nylon-6 and Diamond/Nylon-6 nanocomposite fiber as compared to 346MPa and 321MPa for DN/CNTs/Nylon-6 and Diamond/Nylon-6 nanocomposite fiber without irradiation. The neat Nylon-6 tensile strength was 240MPa. These results are consistent with the activation energy calculated from TGA graphs. DSC analysis result shows that the slight increase in glass transition temperature (Tg) and decrease in melting temperature (Tm) which was expected from high electron-beam radiation dose.

Graphene-Supported Platinum Catalyst-Based Membrane Electrode Assembly for PEM Fuel Cell

NASA Astrophysics Data System (ADS)

Devrim, Yilser; Albostan, Ayhan

2016-08-01

The aim of this study is the preparation and characterization of a graphene-supported platinum (Pt) catalyst for proton exchange membrane fuel cell (PEMFC) applications. The graphene-supported Pt catalysts were prepared by chemical reduction of graphene and chloroplatinic acid (H2PtCl6) in ethylene glycol. X-ray powder diffraction, thermogravimetric analysis (TGA) and scanning electron microscopy have been used to analyze structure and surface morphology of the graphene-supported catalyst. The TGA results showed that the Pt loading of the graphene-supported catalyst was 31%. The proof of the Pt particles on the support surfaces was also verified by energy-dispersive x-ray spectroscopy analysis. The commercial carbon-supported catalyst and prepared Pt/graphene catalysts were used as both anode and cathode electrodes for PEMFC at ambient pressure and 70°C. The maximum power density was obtained for the Pt/graphene-based membrane electrode assembly (MEA) with H2/O2 reactant gases as 0.925 W cm2. The maximum current density of the Pt/graphene-based MEA can reach 1.267 and 0.43 A/cm2 at 0.6 V with H2/O2 and H2/air, respectively. The MEA prepared by the Pt/graphene catalyst shows good stability in long-term PEMFC durability tests. The PEMFC cell voltage was maintained at 0.6 V without apparent voltage drop when operated at 0.43 A/cm2 constant current density and 70°C for 400 h. As a result, PEMFC performance was found to be superlative for the graphene-supported Pt catalyst compared with the Pt/C commercial catalyst. The results indicate the graphene-supported Pt catalyst could be utilized as the electrocatalyst for PEMFC applications.

Biodegradable polymer based ternary blends for removal of trace metals from simulated industrial wastewater.

PubMed

Prakash, N; Arungalai Vendan, S

2016-02-01

The ternary blends consisting of Chitosan (CS), Nylon 6 (Ny 6) and Montmorillonite clay (MM clay) were prepared by the solution blending method with glutaraldehyde. The prepared ternary blends were characterization by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Thermo gravimetric analysis (TGA), Differential scanning calorimetry (DSC) and Scanning electron microscope (SEM). The FTIR results showed that the strong intermolecular hydrogen bondings were established between chitosan, nylon 6 and montmorillonite clay. TGA showed the thermal stability of the blend is enhanced by glutaraldehyde as Crosslink agent. Results of XRD indicated that the relative crystalline of the pure chitosan film was reduced when the polymeric network was reticulated by glutaraldehyde. Finally, the results of scanning electron microscopy (SEM) indicated that the morphology of the blend was rough and heterogenous. Further, it confirms the interaction between the functional groups of the blend components. The extent of removal of the trace metals was found to be almost the same. The removal of these metals at different pH was also done and the maximum removal of the metals was observed at pH 4.5 for both trace metals. Adsorption studies and kinetic analysis have also been made. Moreover, the protonation of amine groups is induced an electrostatic repulsion of cations. When the pH of the solution was more than 5.5, the sorption rate began to decrease. Besides, the quantity of adsorbate on absorbent was fitted as a function in Langmuir and Freundlich isotherm. The sorption kinetics was tested for pseudo first order and pseudo second order reaction. The kinetic experimental data correlated with the second order kinetic model and rate constants of sorption for kinetic models were calculated and accordingly, the correlation coefficients were obtained. Copyright © 2016. Published by Elsevier B.V.

The flux of organic matter through a peatland ecosystem: The role of cellulose, lignin, and their control of the ecosystem oxidation state

NASA Astrophysics Data System (ADS)

Worrall, Fred; Moody, Catherine S.; Clay, Gareth D.; Burt, Tim P.; Rose, Rob

2017-07-01

This study used thermogravimetric analysis (TGA) to study the transit of organic C through a peatland ecosystem. The biomass, litter, peat soil profile, particulate organic matter (POM), and dissolved organic matter (DOM) fluxes were sampled from the Moor House National Nature Reserve, a peat-covered catchment in northern England where both the dry matter and carbon budget for the catchment were known. The study showed that although TGA traces showed distinct differences between organic matter reservoirs and fluxes, the traces could not readily be associated with particular functionalities or elemental properties. The TGA trace shows that polysaccharides are preferentially removed by humification and degradation with residual peat being dominated by lignin compositions. The DOM is derived from the degradation of lignin while the POM is derived from erosion of the peat profile. The carbon lost as gases (CO2 and CH4) was estimated to be composed of 92 to 95% polysaccharide carbon. The composition of the organic matter lost from the peat ecosystem means that the oxidative ratio (OR) of the ecosystem experienced by the atmosphere was between 0.96 and 0.99: currently, the Intergovernmental Panel on Climate Change uses an OR value of 1.1 for all ecosystems.

Carbon speciation in ash, residual waste and contaminated soil by thermal and chemical analyses.

PubMed

Kumpiene, Jurate; Robinson, Ryan; Brännvall, Evelina; Nordmark, Désirée; Bjurström, Henrik; Andreas, Lale; Lagerkvist, Anders; Ecke, Holger

2011-01-01

Carbon in waste can occur as inorganic (IC), organic (OC) and elemental carbon (EC) each having distinct chemical properties and possible environmental effects. In this study, carbon speciation was performed using thermogravimetric analysis (TGA), chemical degradation tests and the standard total organic carbon (TOC) measurement procedures in three types of waste materials (bottom ash, residual waste and contaminated soil). Over 50% of the total carbon (TC) in all studied materials (72% in ash and residual waste, and 59% in soil) was biologically non-reactive or EC as determined by thermogravimetric analyses. The speciation of TOC by chemical degradation also showed a presence of a non-degradable C fraction in all materials (60% of TOC in ash, 30% in residual waste and 13% in soil), though in smaller amounts than those determined by TGA. In principle, chemical degradation method can give an indication of the presence of potentially inert C in various waste materials, while TGA is a more precise technique for C speciation, given that waste-specific method adjustments are made. The standard TOC measurement yields exaggerated estimates of organic carbon and may therefore overestimate the potential environmental impacts (e.g. landfill gas generation) of waste materials in a landfill environment. Copyright © 2010 Elsevier Ltd. All rights reserved.

Levels-of-processing effects on recollection and familiarity during transient global amnesia and after recovery.

PubMed

Thoma, Patrizia; Schwarz, Michael; Daum, Irene

2010-11-01

The aim of the present study was to investigate the pattern of recollection and familiarity deficits and the modulation of recognition memory performance by the depth of encoding (deep vs. shallow) in transient global amnesia (TGA). Ten patients with TGA and 11 control subjects were assessed during the acute stage and after recovery 7 to 19 days later. Both recollection and familiarity were impaired in the acute stage and showed significant, albeit not complete, recovery by the time of the postacute assessment. The patients did, however, show a significant levels-of-processing effect, which was significantly reduced in acute TGA, but not at follow-up. The significant levels-of-processing effect during acute TGA might be linked to recruitment of the prefrontal cortex. (c) 2010 APA, all rights reserved

Influence of Aluminum Passivation on the Reaction Mechanism: Flame Propagation Studies

DTIC Science & Technology

2009-01-01

synthesis and characterization of Al nanoparticles without an oxide shell is presented in refs 15- 18. In summary, SEM, thermogravimetric analysis (TGA) and...al.1 examined the oxidation behavior of ultrafine grain aluminum powder using Rutherford back- scattering spectrometry, thermogravimetric analysis , and...to opposite predictions in nanoparticle design. The diffusion mechanism suggests that the reduction Dr complete elimination of the oxide shell will

Reduction-resistant and reduction-catalytic double-crown nickel nanoclusters

NASA Astrophysics Data System (ADS)

Zhu, Min; Zhou, Zhou, Shiming; Yao, Chuanhao; Liao, Lingwen; Wu, Zhikun

2014-11-01

In this work, an attempt to synthesize zero-valent Ni nanoclusters using the Brust method resulted in an unexpected material, Ni6(SCH2CH2Ph)12, which is a nanoscale Ni(ii)-phenylethanethiolate complex and a hexameric, double-crown-like structure, as determined by a series of characterizations, including mass spectrometry (MS), thermal gravimetric analysis (TGA), single-crystal X-ray diffraction (XRD), and X-ray photoelectron spectrometry (XPS). An interesting finding is that this complex is resistant to aqueous BH4-. Investigations into other metal-phenylethanethiolate and Ni-thiolate complexes reveal that this property is not universal and appears only in complexes with a double-crown-like structure, indicating the correlation between this interesting property and the complexes' special structure. Another interesting finding is that the reduction-resistant Ni6(SCH2CH2Ph)12 exhibits remarkably higher catalytic activity than a well-known catalyst, Au25(SCH2CH2Ph)18, toward the reduction of 4-nitrophenol at low temperature (e.g., 0 °C). This work will help stimulate more research on the properties and applications of less noble metal nanoclusters.In this work, an attempt to synthesize zero-valent Ni nanoclusters using the Brust method resulted in an unexpected material, Ni6(SCH2CH2Ph)12, which is a nanoscale Ni(ii)-phenylethanethiolate complex and a hexameric, double-crown-like structure, as determined by a series of characterizations, including mass spectrometry (MS), thermal gravimetric analysis (TGA), single-crystal X-ray diffraction (XRD), and X-ray photoelectron spectrometry (XPS). An interesting finding is that this complex is resistant to aqueous BH4-. Investigations into other metal-phenylethanethiolate and Ni-thiolate complexes reveal that this property is not universal and appears only in complexes with a double-crown-like structure, indicating the correlation between this interesting property and the complexes' special structure. Another interesting finding is that the reduction-resistant Ni6(SCH2CH2Ph)12 exhibits remarkably higher catalytic activity than a well-known catalyst, Au25(SCH2CH2Ph)18, toward the reduction of 4-nitrophenol at low temperature (e.g., 0 °C). This work will help stimulate more research on the properties and applications of less noble metal nanoclusters. Electronic supplementary information (ESI) available: Experimental section, detailed structural data, MS analyses of M-SCH2CH2Ph complexes, stability study of Ni6 and TGA analysis of Au25(SCH2CH2Ph)18. See DOI: 10.1039/c4nr04981k

Enhancing antioxidant activity of sesamol at frying temperature by addition of additives through reducing volatility

USDA-ARS?s Scientific Manuscript database

Additives were evaluated to investigate their effects on volatility of sesamol at frying temperature with the hypothesis that the interaction between an additive and sesamol would reduce sesamol volatility. Twenty-two additive:sesamol combinations were examined by thermogravimetric analysis (TGA) un...

Novel Claycunbic to Eliminate Micropollutants and Vibrio fischeri from Water

EPA Science Inventory

Montmorillonite clay (K10) was used as a precursor for the synthesis of a catalytic adsorbent, Claycunbic (Bi/Cu-pillared K10), which was characterized by SEM (EDS), TEM, XRD, BET, TGA and XPS analysis. The catalytic adsorption of cationic dye methylene blue (MB), anionic dye met...

Chemical Modification of Kraft Lignin: Effect on Chemical and Thermal Properties

Treesearch

Yao Chen; Nicole M. Stark; Zhiyong Cai; Charles R. Frihart; Linda F. Lorenz; Rebecca E. Ibach

2014-01-01

Esterified kraft lignins (KL) were prepared by reaction with maleic anhydride (MA), succinic anhydride (SA), and phthalic anhydride (PA) in acetone solutions. The esterified lignins were characterized using ATR-FTIR, solid state CP-MAS 13C NMR spectroscopy, thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). PA...

Novel Electroactive Polymers as Environmentally Compliant Coatings for Corrosion Control

DTIC Science & Technology

2006-02-03

Gravametric Analysis (TGA) and Differential Scanning Calorimetry (DSC), respectively. In this work the polymers were characterized by cyclic voltametry ...or less. The Temperature Step / Frequency Sweep method was employed where data were collected from –40 to 100°C and 0.1-100 Hz at a resolution of

In vivo evaluation of an oral drug delivery system for peptides based on S-protected thiolated chitosan.

PubMed

Dünnhaupt, Sarah; Barthelmes, Jan; Iqbal, Javed; Perera, Glen; Thurner, Clemens C; Friedl, Heike; Bernkop-Schnürch, Andreas

2012-06-28

The aim of the present study was the development and evaluation in vitro as well as in vivo of an oral delivery system based on a novel type of thiolated chitosan, so-called S-protected thiolated chitosan, for the peptide drug antide. The sulfhydryl ligand thioglycolic acid (TGA) was covalently attached to chitosan (CS) in the first step of modification. In the second step, these thiol groups of thiolated chitosan were protected by disulfide bond formation with the thiolated aromatic residue 6-mercaptonicotinamide (6-MNA). Absorptive transport studies of antide were evaluated ex vivo using rat intestinal mucosa. Matrix tablets of each polymer sample were prepared and their effect on the absorption of antide evaluated in vivo in male Sprague-Dawley rats. In addition, tablets were examined in terms of their disintegration, swelling and drug release behavior. The resulting S-protected thiomer (TGA-MNA) exhibited 840μmol of covalently linked 6-MNA per gram thiomer. Based on the implementation of this hydrophobic ligand on the thiolated backbone, the disintegration behavior was reduced greatly and a controlled release of the peptide could be achieved. Furthermore, permeation studies with TGA-MNA on rat intestine revealed a 4.5-fold enhanced absorptive transport of the peptide in comparison to antide in solution. Additional in vivo studies confirmed the potential of this novel conjugate. Oral administration of antide in solution led to only very small detectable quantities in plasma with an absolute and relative bioavailability (BA) of 0.003 and 0.03%, only. In contrast, with antide incorporated in TGA-MNA matrix tablets an absolute and relative BA of 1.4 and 10.9% could be reached, resulting in a 421-fold increased area under the plasma concentration time curve (AUC) compared to the antide solution. According to these results, S-protected thiolated chitosan as oral drug delivery system might be a valuable tool for improving the bioavailability of peptides. Copyright © 2012 Elsevier B.V. All rights reserved.

Development and Pre-Clinical Evaluation of a Novel Prostate-Restricted Replication Competent Adenovirus-AD-IU-1

DTIC Science & Technology

2006-05-01

CTCTGTTTGTGGA A A A TT TTA A A CTA CTGGTTTA A TTT CT TTA TTGGTTGTA A TA TGA CTA TTTTA CGTCA TA TA A CA A TTTTTA TT GTTTGT TA A A TGA CTTTA TTGTTTGTC A...radiotracer 1 was 0.8–1.2 Ci /mmol at end of synthesis (EOS). In comparison with the results reported in the literature,[15,25,33,34] several improvements in...99%, and the chemical purity of radiotracer 1 was 93%. The average (n ¼ 3–5) specific radio- activity of radiotracer 1 was 0.8–1.2 Ci /mmol at EOS

The reverse boomerang sign: a marker for first-trimester transposition of great arteries.

PubMed

Bravo-Valenzuela, Nathalie Jeanne; Peixoto, Alberto Borges; Araujo Júnior, Edward; Da Silva Costa, Fabricio; Meagher, Simon

2017-10-12

To describe a new sonographic marker of transposition of great arteries (TGA) during the first-trimester screening. We reviewed six cases of TGA from 2013 to 2016 in which an antenatal diagnosis of TGA at first-trimester screening (11-13 + 6 weeks of gestation) was confirmed postnatally. We specifically assessed images obtained by scanning the fetal heart in three vessels (3V) and three-vessel with trachea (3VT) views using color Doppler. The "reverse boomerang" sign was defined as a reverse curvature of right ventricle outflow tract (RVOT) at level of the 3VT view. We described six cases of confirmed TGA, five singletons and one twin pregnancy, among which only two vessels and the reverse curvature of RVOT (reverse boomerang sign) was demonstrated in the first-trimester screening at level of 3VT view. Ventricular septal defects were observed in three cases, and double outlet right ventricle in one case. No other cardiac or extracardiac anomalies were identified. Termination of pregnancy was not performed in any case. Our series case suggests that the reverse boomerang sign may improve the early prenatal screening for TGA.

Persistent Pulmonary Hypertension of the Newborn with D-transposition of the Great Arteries: Management and Prognosis.

PubMed

Sallaam, Salaam; Natarajan, Girija; Aggarwal, Sanjeev

2016-05-01

There is a paucity of data on clinical correlates and outcomes of pulmonary hypertension (PH) in patients with D-transposition of the great arteries (D-TGA) in the era of inhaled nitric oxide (iNO) and extracorporeal membrane oxygenation (ECMO). Our objective was to compare clinical characteristics and outcomes of infants with D-TGA with and without PH, defined as hypoxemia that required iNO and/or ECMO. We undertook a single-center retrospective chart review involving infants with gestational age ≥32 weeks with D-TGA who, underwent arterial switch operation over a 12-year period. Demographic and clinical data, details of the repair and postoperative complications were abstracted. Our cohort (n = 93), 61 (66%) of whom were males, had a mean (SD) gestational age and birth weight of 38.7 (1.8) weeks and 3.2 (0.6) kg, respectively. PH requiring iNO and/or ECMO was noted in 20 (21.5%) infants. Infants with PH had significantly lower birth weight [2.8 (0.56) vs. 3.33 (0.61)] and gestational age [37.7 (2.1) vs. 38.9 (1.7)] than those without PH. Rates of postoperative complications (duration of pressors, sedative medicaiton and duration of hospital stay, and mechanical ventilation were higher in the group with PH. Of the five (5.4%) infants who died, four received iNO and ECMO. Death or postoperative complications tended to be associated with lower gestational age [OR 0.689; 95% CI: 0.469-1.012, P = 0.058] but not with D-TGA category or bypass duration. Despite aggressive treatment with iNO and ECMO, the coexistence of PH in this population is associated with higher rates of mortality and postoperative complications. Our results also suggest that an early term birth may be associated with PH in infants with D-TGA. © 2015 Wiley Periodicals, Inc.

Thermogravimetric and microscopic analysis of SiC/SiC materials with advanced interfaces

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

Windisch, C.F. Jr.; Jones, R.H.; Snead, L.L.

1997-04-01

The chemical stability of SiC/SiC composites with fiber/matrix interfaces consisting of multilayers of SiC/SiC and porous SiC have been evaluated using a thermal gravimetric analyzer (TGA). Previous evaluations of SiC/SiC composites with carbon interfacial layers demonstrated the layers are not chemically stable at goal use temperatures of 800-1100{degrees}C and O{sub 2} concentrations greater than about 1 ppm. No measureable mass change was observed for multilayer and porous SiC interfaces at 800-1100{degrees}C and O{sub 2} concentrations of 100 ppm to air; however, the total amount of oxidizable carbon is on the order of the sensitivity of the TGA. Further studies aremore » in progress to evaluate the stability of these materials.« less

Mathematical tool from corn stover TGA to determine its composition.

PubMed

Freda, Cesare; Zimbardi, Francesco; Nanna, Francesco; Viola, Egidio

2012-08-01

Corn stover was treated by steam explosion process at four different temperatures. A fraction of the four exploded matters was extracted by water. The eight samples (four from steam explosion and four from water extraction of exploded matters) were analysed by wet chemical way to quantify the amount of cellulose, hemicellulose and lignin. Thermogravimetric analysis in air atmosphere was executed on the eight samples. A mathematical tool was developed, using TGA data, to determine the composition of corn stover in terms of cellulose, hemicellulose and lignin. It uses the biomass degradation temperature as multiple linear function of the cellulose, hemicellulose and lignin content of the biomass with interactive terms. The mathematical tool predicted cellulose, hemicellulose and lignin contents with average absolute errors of 1.69, 5.59 and 0.74 %, respectively, compared to the wet chemical method.

Microwave-assisted synthesis of Pt/CNT nanocomposite electrocatalysts for PEM fuel cells.

PubMed

Zhang, Weimin; Chen, Jun; Swiegers, Gerhard F; Ma, Zi-Feng; Wallace, Gordon G

2010-02-01

Microwave-assisted heating of functionalized, single-wall carbon nanotubes (FCNTs) in ethylene glycol solution containing H(2)PtCl(6), led to the reductive deposition of Pt nanoparticles (2.5-4 nm) over the FCNTs, yielding an active catalyst for proton-exchange membrane fuel cells (PEMFCs). In single-cell testing, the Pt/FCNT composites displayed a catalytic performance that was superior to Pt nanoparticles supported by raw (unfunctionalized) CNTs (RCNTs) or by carbon black (C), prepared under identical conditions. The supporting single-wall carbon nanotubes (SWNTs), functionalized with carboxyl groups, were studied by thermogravimetric analysis (TGA), cyclic voltammetry (CV), and Raman spectroscopy. The loading level, morphology, and crystallinity of the Pt/SWNT catalysts were determined using TGA, SEM, and XRD. The electrochemically active catalytic surface area of the Pt/FCNT catalysts was 72.9 m(2)/g-Pt.

Synthesis, spectral studies and biological evaluation of 2-aminonicotinic acid metal complexes

NASA Astrophysics Data System (ADS)

Nawaz, Muhammad; Abbasi, Muhammad Waseem; Hisaindee, Soleiman; Zaki, Muhammad Javed; Abbas, Hira Fatima; Mengting, Hu; Ahmed, M. Arif

2016-05-01

We synthesized 2-aminonicotinic acid (2-ANA) complexes with metals such as Co(II), Fe(III), Ni(II), Mn(II), Zn(II), Ag(I),Cr(III), Cd(II) and Cu(II) in aqueous media. The complexes were characterized and elucidated using FT-IR, UV-Vis, a fluorescence spectrophotometer and thermo gravimetric analysis (TGA). TGA data showed that the stoichiometry of complexes was 1:2 metal/ligand except for Ag(I) and Mn(II) where the ratio was 1:1. The metal complexes showed varied antibacterial, fungicidal and nematicidal activities. The silver and zinc complexes showed highest activity against Bacillus subtilis and Bacillus licheniformis respectively. Fusarium oxysporum was highly susceptible to nickel and copper complexes whereas Macrophomina phaseolina was completely inert to the complexes. The silver and cadmium complexes were effective against the root-knot nematode Meloidogyne javanica.

Thermophysical characterization of the seeds of invasive Chinese tallow tree: importance for biofuel production.

PubMed

Picou, Laura; Boldor, Doran

2012-10-16

The limited supply of traditional fossil based fuels, and increased concern about their environmental impact has driven the interest in the utilization of biomass based energy sources, including those that are underutilized or otherwise nuisance species such as Chinese tallow trees (Triadica sebifera [L.]). This species is a prolific seeds producer, and this paper shows that they contain more than 50% lipids by mass that are suitable for conversion into biodiesel. We present here, for the first time, the seeds' thermophysical properties important for biofuel production. The seeds were characterized using thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and ultimate analysis; their thermal conductivity, thermal diffusivity, and specific heat were determined. The characterization results were correlated to fatty acid composition and lipid content for whole seeds and individual layers, as well as to the protein, hemicellulose, cellulose, and lignin content. The TGA analysis indicated the presence, in addition to lipids, of hemicellulose, cellulose, lignin, and proteins, depending on the layer analyzed. Thermal conductivity and specific heat were, respectively 0.14 ± 0.007 W/mK and 3843.5 ± 171.16 J/kgK for wax, 0.20 ± 0.002 W/mK and 2018.7 ± 5.18 J/kgK for shells, 0.13 ± 0.0 W/mK and 1237 ± 3.15 J/kgK for internal kernel, and 0.13 ± 0.000 W/mK and 2833.9 ± 104.11 J/kgK for whole seeds. These properties and characterization method can be further used in engineering analysis used to determine the most optimum processing method for production of biofuels from this feedstock.

Physicochemical properties and combustion behavior of duckweed during wet torrefaction.

PubMed

Zhang, Shuping; Chen, Tao; Li, Wan; Dong, Qing; Xiong, Yuanquan

2016-10-01

Wet torrefaction of duckweed was carried out in the temperature range of 130-250°C to evaluate the effects on physicochemical properties and combustion behavior. The physicochemical properties of duckweed samples were investigated by ultimate analysis, proximate analysis, FTIR, XRD and SEM techniques. It was found that wet torrefaction improved the fuel characteristics of duckweed samples resulting from the increase in fixed carbon content, HHVs and the decrease in nitrogen and sulfur content and atomic ratios of O/C and H/C. It can be seen from the results of FTIR, XRD and SEM analyses that the dehydration, decarboxylation, solid-solid conversion, and condensation polymerization reactions were underwent during wet torrefaction. In addition, the results of thermogravimetric analysis (TGA) in air indicated that wet torrefaction resulted in significant changes on combustion behavior and combustion kinetics parameters. Duckweed samples after wet torrefaction behaved more char-like and gave better combustion characteristics than raw sample. Copyright © 2016 Elsevier Ltd. All rights reserved.

Comparison of the combustion reactivity of TGA and drop tube furnace chars from a bituminous coal

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

Katherine Le Manquais; Colin Snape; Ian McRobbie

This paper compares the reactivity of chars generated in a drop tube furnace (DTF) to those from TGA. The implications of devolatilization temperature, heating rate and residence time are considered. For the smaller particle size ranges of the bituminous coal investigated (ATC), optimized devolatilization procedures were used to generate corresponding TGA burnout rates between the two char types. However, with fractions of >75 {mu}m, the DTF chars showed an increased burnout propensity when moving from combustion regime II to combustion regime III. Scanning electron microscope (SEM) images and internal surface areas indicate that this is because of incompatible char morphologies.more » Thus, while chars produced under the conditions of TGA pyrolysis strongly resemble raw coal and display an undeveloped pore network; the DTF chars are highly porous, extensively swollen and possess considerably larger internal surface areas. Subsequently, char burnout variability was quantified, with the reactivity distribution for the DTF samples found to be up to an order of magnitude more significant than for the TGA chars. This is attributed to a fluctuating devolatilization environment on the DTF. Finally, a TGA study observed a robust particle size based compensation effect for the TGA chars, with the relative reaction rates and activation energies demonstrating the presence of internal diffusion control. However this phenomenon was partly alleviated for the DTF chars, since their higher porosities reduce mass transfer restrictions. Moreover, it should be realized that DTF char fractions of <38 {mu}m, including those required to ensure true intrinsic control under the investigated burnout conditions, cannot be produced directly. This is because of bridging and sloughing in the DTF's screw-feeder. Instead, such samples must be created by grinding larger particles, which destroys the char's existing porosity. 60 refs., 9 figs., 5 tabs.« less

Surface degradation of polymer insulators under accelerated climatic aging in weather-ometer

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

Xu, G.; McGrath, P.B.; Burns, C.W.

1996-12-31

Climatic aging experiments were conducted on two types of outdoor polymer insulators by using a programmable weather-ometer. The housing materials for the insulators were silicone rubber (SR) and ethylene propylene diene monomer (EPDM). The accelerated aging stresses were comprised of ultraviolet radiation, elevated temperature, temperature cycling, thermal shock and high humidity. Their effects on the insulator surface conditions and electrical performance wee examined through visual inspection and SEM studies, contact angle measurements, thermogravimetric analysis (TGA), energy dispersive spectroscopy (EDS) analysis, and 50% impulse flashover voltage tests. The results showed a significant damage on the insulator surface caused by some ofmore » the imposed aging stresses. The EDS analysis suggested a photooxidation process that happened on the insulator surface during the aging period.« less

Influence of Blood Lipids on Global Coagulation Test Results

PubMed Central

Kim, Jung-Ah; Kim, Ji-Eun; Song, Sang Hoon

2015-01-01

Background High levels of blood lipids have been associated with high levels of coagulation factors. We investigated whether blood lipids influence the results of global coagulation tests, including prothrombin time (PT), activated partial thromboplastin time (aPTT), and thrombin generation assay (TGA). Methods PT, aPTT, and TGA, along with procoagulant and anticoagulant factors, were measured in 488 normal individuals. Vitamin K status was assessed with prothrombin-induced by vitamin K absence-II (PIVKA-II). Results The procoagulant factors II, VII, IX, X, and XI and anticoagulant factors protein C and protein S showed significant correlations with triglyceride, and the procoagulant factors II, V, VII, IX, X, XI, and XII and anticoagulant factors antithrombin and protein C correlated with total cholesterol. There were no correlations of blood lipid levels with PIVKA-II levels. Subjects with high triglyceride levels (≥200 mg/dL) showed shorter PT values than those with lower triglyceride levels. However, aPTT value was not changed in terms of blood lipid levels. In both 1 and 5 pM tissue factor-induced TGAs, subjects in the high-triglyceride or high-cholesterol groups (≥240 mg/dL) had high levels of lag time, time-to-peak, and endogenous thrombin potential. Total cholesterol was a significant determinant of PT and TGA values. Conclusion High blood lipids were related with increased coagulation activity in a normal population. Our findings are expected to help interpret the global coagulation test results in individuals with high lipid levels. PMID:25553275

Use of Several Thermal Analysis Techniques on a Hypalon Paint Coating for the Solid Rocket Booster (SRB) of the Space Shuttle

NASA Technical Reports Server (NTRS)

Wingard, Charles D.

1999-01-01

White Hypalon paint is brush-applied as a moisture barrier coating over cork surfaces on each of the two Space Shuttle SRBS. Fine cracks have been observed in the Hypalon coating three times historically on laboratory witness panels, but never on flight hardware. Recent samples of the cracked and standard ("good") Hypalon were removed from cork surfaces and were tested by Thermal Gravimetric Analysis (TGA), Thermomechanical (TMA) and Differential Scanning Calorimetry (DSC) thermal analysis techniques. The TGA data showed that at 700 C, where only paint pigment solids remain, the cracked material had about 9 weight percent more material remaining than the standard material, probably indicating incomplete mixing of the paint before it was brush-applied to produce the cracked material. Use of the TMA film tension method showed that the average static modulus vs. temperature was about 3 to 6 times higher for the cracked material than for the standard material, indicating a much higher stiffness for the cracked Hypalon. The TMA data also showed than an increased coating thickness for the cracked Hypalon was not a factor in the anomaly.

Performance assessment of MCM-48 ceramic composite membrane by separation of AlCl3 from aqueous solution.

PubMed

Kumar Basumatary, Ashim; Kumar Ghoshal, Aloke; Pugazhenthi, G

2016-12-01

Three dimensional ordered mesoporous MCM-48 membrane was fabricated on a circular shaped ceramic support by in-situ hydrothermal method. The synthesized MCM-48 powder and MCM-48 ceramic composite membrane were characterized by X-ray diffraction (XRD), thermogravimetric analysis (TGA) and field emission scanning electron microscopy (FESEM). The porosity and pore size of the composite membrane are reduced considerably by the deposition of MCM-48 on the support. The formation of MCM-48 is verified by the XRD analysis. Three stepwise mechanisms for surfactant removal are observed by TGA analysis. FESEM images clearly signify the deposition of MCM-48 on the ceramic support. The pure water flux of the support and MCM-48 composite membrane is found to be 3.63×10 -6 and 4.18×10 -8 m 3 /m 2 skPa, respectively. The above prepared MCM-48 ceramic composite membrane is employed for the removal of AlCl 3 from aqueous solution and the highest rejection of 81% is obtained at an applied pressure of 276kPa with salt concentration of 250ppm. Copyright © 2015 Elsevier Inc. All rights reserved.

Reduction of graphene oxide by aniline with its concomitant oxidative polymerization.

PubMed

Xu, Li Qun; Liu, Yi Liang; Neoh, Koon-Gee; Kang, En-Tang; Fu, Guo Dong

2011-04-19

Graphene oxide (GO) nanosheets are readily reduced by aniline above room temperature in an aqueous acid medium, with the aniline simultaneously undergoing oxidative polymerization to produce the reduced graphene oxide-polyaniline nanofiber (RGO-PANi) composites. The resulting RGO-PANi composites and RGO (after dissolution of PANi) were characterized by XPS, XRD analysis, TGA, UV-visible absorption spectroscopy, and TEM. It was also found that the RGO-PANi composites exhibit good specific capacitance during galvanostatic charging-discharging when used as capacitor electrodes. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Spectroscopic characterization of nanohydroxyapatite synthesized by molten salt method.

PubMed

Gopi, D; Indira, J; Kavitha, L; Kannan, S; Ferreira, J M F

2010-10-01

Hydroxyapatite (HAP) nanopowders were synthesized by molten salt method at 260 degrees C. The as-prepared powders were characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscope (SEM) and thermo gravimetric analysis (TGA). With the aid of the obtained results the effect of calcining time on the crystallinity, size and morphology of HAP nanopowders is presented. The HAP nanopowders synthesized by molten salt method consist of pure phase of HAP without any impurities and showed the rod-like morphology without detectable decomposition up to 1100 degrees C. Copyright 2010 Elsevier B.V. All rights reserved.

Electrical transport and thermochromic properties of polyaniline/chitosan/Co3O4 ternary nano composite

NASA Astrophysics Data System (ADS)

V, Mini; Kamath, Archana; S, Raghu; Chapi, Sharanappa; H, Devendrappa

2015-06-01

A new Polyaniline/ chitosan/ Co3O4 (CPAESCO) ternary nanocomposite is prepared by in situ oxidation polymerization of aniline in the presence of (NH4)2S2O8, chitosan and Co3O4. The Structural, Thermal, Optical and Electrical features of Polyaniline (PANI), Polyaniline/ chitosan (CPANI) and CPAESCO were analyzed using FT-IR, TGA, UV-vis analysis and Impedance spectroscopy by varying temperature. The results show that the introduction of the Co3O4 nanoparticles into CPANI matrix enhanced its properties. Mott's parameters show 3D -VRH Type conduction in it.

Preparation and characterization of a siloxane containing bismaleimide

NASA Technical Reports Server (NTRS)

Maudgal, S.; St. Clair, T. L.

1984-01-01

A novel siloxane containing bismaleimide has been prepared by reacting maleic anhydride, benzophenonetetracarboxylic dianhydride and bis(gamma-aminopropyl)tetramethyldisiloxane. Characterization of this monomer was done by comparing its nuclear magnetic resonance spectrum (NMR) to those of model compounds. Solubility of the prepolymer was tested in amide, chlorinated and ether solvents. Films were cast from solution as well as by melt processing and a cure cycle was determined. Infrared spectrum (IR) of the resulting film was obtained. Thermal polymerization was investigated by differential scanning calorimetry (DSC). Thermal properties of the cured resin were followed by means of thermogravimetric analysis (TGA), torsional braid analysis (TBA) and dynamic mechanical analysis (DMA). Thermomechanical analysis (TMA) was used to study the effect of postcure on the glass transition temperature (Tg) of the resin. Adhesive strength of the resin was obtained at ambient temperature.

Better latent heat and specific heat of stearic acid with magnetite/graphene nanocomposite addition for thermal storage application

NASA Astrophysics Data System (ADS)

Andiarto, R.; Nuryadin, M. K.; Taufik, A.; Saleh, R.

2017-04-01

In our previous study, the addition of Magnetite (Fe3O4) into Stearic acid (Sa) as an organic phase change material (PCM) shows an enhancement in the latent heat for thermal energy storage applications. The latent heat of the PCM can also be increased by adding graphene material. Therefore, in this research, the thermal properties of Sa have been studied by the sonication method for several different concentrations of Fe3O4/Graphene nanocomposite additions. The structural properties of all of the samples were observed by X-Ray diffraction (XRD). Melting-solidifying behavior and specific heat value were measured by differential scanning calorimetry (DSC). The thermal degradation process of all samples was investigated by thermogravimetric analysis (TGA). Based on the DSC results, the presence of Fe3O4/Graphene in the Sa enhances the latent heat up to 20%. The specific heat value of the mixture was also found to be increased as the concentration of Fe3O4/Graphene to Sa increased. The TGA results show a lowered thermal degradation process of the Sa by the addition of the Fe3O4/Graphene which indicates a higher thermal stability of the mixture. In conclusion, the results demonstrate that the addition of Fe3O4/Graphene to Sa improves both the sensible heat and the latent heat of the mixture which are very important for thermal energy storage applications

Novel nanohybrids of cobalt(III) Schiff base complexes and clay: synthesis and structural determinations.

PubMed

Kianfar, Ali Hossein; Mahmood, Wan Ahmad Kamil; Dinari, Mohammad; Azarian, Mohammad Hossein; Khafri, Fatemeh Zare

2014-06-05

The [Co(Me(2)Salen)(PBu(3))(OH(2))]BF4 and [Co(Me(2)Salen)(PPh(3))(Solv)]BF(4), complexes were synthesized and characterized by FT-IR, UV-Vis, (1)H NMR spectroscopy and elemental analysis techniques. The coordination geometry of [Co(Me(2)Salen)(PPh(3))(H(2)O)]BF(4) was determined by X-ray crystallography. It has been found that the complex is containing [Co(Me(2)Salen)(PPh(3))(H(2)O)]BF(4) and [Co(Me(2)Salen)(PPh(3))(EtOH)]BF(4) hexacoordinate species in the solid state. Cobalt atom exhibits a distorted octahedral geometry and the Me(2)Salen ligand has the N2O2 coordinated environment in the equatorial plane. The [Co(Me(2)Salen)(PPh(3))(H(2)O)]BF(4) complex shows a dimeric structure via hydrogen bonding between the phenolate oxygen and hydrogens of coordinated H2O molecule. These complexes were incorporated into Montmorillonite-K10 nanoclay. The modified clays were identified by FT-IR, XRD, EDX, TGA/DTA, SEM and TEM techniques. According to the XRD results of the new nanohybrid materials, the Schiff base complexes are intercalated in the interlayer spaces of the clay. SEM and TEM micrographs show that the resulting hybrid nanomaterials have layer structures. Also, TGA/DTG results show that the intercalation reaction was taken place successfully. Copyright © 2014. Published by Elsevier B.V.

Preparation and characterization of flame retardant n-hexadecane/silicon dioxide composites as thermal energy storage materials.

PubMed

Fang, Guiyin; Li, Hui; Chen, Zhi; Liu, Xu

2010-09-15

Flame retardant n-hexadecane/silicon dioxide (SiO(2)) composites as thermal energy storage materials were prepared using sol-gel methods. In the composites, n-hexadecane was used as the phase change material for thermal energy storage, and SiO(2) acted as the supporting material that is fire resistant. In order to further improve flame retardant property of the composites, the expanded graphite (EG) was added in the composites. Fourier transformation infrared spectroscope (FT-IR), X-ray diffractometer (XRD) and scanning electronic microscope (SEM) were used to determine chemical structure, crystalloid phase and microstructure of flame retardant n-hexadecane/SiO(2) composites, respectively. The thermal properties and thermal stability were investigated by a differential scanning calorimeter (DSC) and a thermogravimetric analysis apparatus (TGA), respectively. The SEM results showed that the n-hexadecane was well dispersed in the porous network of the SiO(2). The DSC results indicated that the melting and solidifying latent heats of the composites are 147.58 and 145.10 kJ/kg when the mass percentage of the n-hexadecane in the composites is 73.3%. The TGA results showed that the loading of the EG increased the charred residue amount of the composites at 700 degrees C, contributing to the improved thermal stability of the composites. It was observed from SEM photographs that the homogeneous and compact charred residue structure after combustion improved the flammability of the composites. Copyright 2010 Elsevier B.V. All rights reserved.

Design and Development of Novel Hierarchically Ordered Block Copolymer-Magnetoelectric Particle Nanocomposites

DTIC Science & Technology

2012-06-08

microscopy (JEOL 1200EX STEM). The volume fraction of BaTiO3 nanoparticles in the PS-BTO nanocomposites was determined by thermogravimetric analysis ...encapsulated in the 9.8±0.4-nm NP was approximately only 13.8% based on the thermogravimetric analysis (TGA) measurement (Supporting Material Section...the properties of the constituents and their spatial arrangement. Nanocomposites of polymer/ nanoparticle , formed by incorporating nanoparticles into

Isolation and characterization of nanocrystalline cellulose from roselle-derived microcrystalline cellulose.

PubMed

Kian, Lau Kia; Jawaid, Mohammad; Ariffin, Hidayah; Karim, Zoheb

2018-07-15

Roselle fiber is a renewable and sustainable agricultural waste enriched with cellulose polysaccharides. The isolation of Nanocrystalline cellulose (NCC) from roselle-derived microcrystalline cellulose (MCC) is an alternative approach to recover the agricultural roselle plant residue. In the present study, acid hydrolysis with different reaction time was carried out to degrade the roselle-derived MCC to form NCC. The characterizations of isolated NCC were conducted through Fourier Transform Infrared Ray (FTIR), Transmission Electron Microscopy (TEM), Field Emission Scanning Electron Microscopy (FESEM), Atomic Force Microscopy (AFM), Dynamic Light Scattering (DLS), Energy Dispersive Spectroscopy (EDS), X-ray Diffraction (XRD), Thermogravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC). As evaluated from the performed morphological investigations, the needle-like shape NCC nanostructures were observed under TEM and AFM microscopy studies, while irregular rod-like shape of NCC was observed under FESEM analysis. With 60min hydrolysis time, XRD analysis demonstrated the highest NCC crystallinity degree with 79.5%. In thermal analysis by TGA and DSC, the shorter hydrolysis time tended to produce NCC with higher thermal stability. Thus, the isolated NCC from roselle-derived MCC has high potential to be used in application of pharmaceutical and biomedical fields for nanocomposite fabrication. Copyright © 2018 Elsevier B.V. All rights reserved.

Direct synthesis of hydrophobic graphene-based nanosheets via chemical modification of exfoliated graphene oxide.

PubMed

Wang, Jigang; Wang, Yongsheng; He, Dawei; Liu, Zhiyong; Wu, Hongpeng; Wang, Haiteng; Zhao, Yu; Zhang, Hui; Yang, Bingyang; Xu, Haiteng; Fu, Ming

2012-08-01

Hydrophobic graphene-based material at the nanoscale was prepared by treatment of exfoliated graphene oxide with organic isocyanates. The lipophilic modified graphene oxide (LMGO) can then be exfoliated into the functionalized graphene nanoplatelets that can form a stable dispersion in polar aprotic solvents. AFM image shows the thickness of LMGO is approximately 1 nm. Characterization of LMGO by elemental analysis suggested that the chemical treatment results in the functionalization of the carboxyl and hydroxyl groups in GO via formation of amides and carbamate esters, respectively. The degree of GO functionalization can be controlled via either the reactivity of the isocyanate or the reaction time. Then we investigated the thermal properties of the SPFGraphene by using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC), the TGA curve shows a greater weight loss of approximately 20% occurred indicating removal of functional groups from the LMGO sheets and an obvious exothermic peak at 176 degrees can be observed from 150 to 250 degrees. We also compared the structure of graphene oxide with the structure of chemical treated graphene oxide by FT-IR spectroscopy. The morphology and microstructure of the LMGO nanosheets were also characterized by SEM and XRD. Graphene can be used to fabricate a wide range of simple electronic devices such as field-effect transistors, resonators, quantum dots and some other extensive industrial manufacture such as super capacitor, li ion battery, solar cells and even transparent electrodes in device applications.

Thermal stability of LiPF 6 salt and Li-ion battery electrolytes containing LiPF 6

NASA Astrophysics Data System (ADS)

Yang, Hui; Zhuang, Guorong V.; Ross, Philip N.

The thermal stability of the neat lithium hexafluorophosphate (LiPF 6) salt and of 1 molal (m) solutions of LiPF 6 in prototypical Li-ion battery solvents was studied with thermogravimetric analysis (TGA) and on-line Fourier transform infrared (FTIR). Pure LiPF 6 salt is thermally stable up to 107 °C in a dry inert atmosphere, and its decomposition path is a simple dissociation producing lithium fluoride (LiF) as solid and PF 5 as gaseous products. In the presence of water (300 ppm) in the carrier gas, its decomposition onset temperature is lowered as a result of direct thermal reaction between LiPF 6 and water vapor to form phosphorous oxyfluoride (POF 3) and hydrofluoric acid (HF). No new products were observed in 1 m solutions of LiPF 6 in ethylene carbonate (EC), dimethyl carbonate (DMC) and ethyl methyl carbonate (EMC) by on-line TGA-FTIR analysis. The storage of the same solutions in sealed containers at 85 °C for 300-420 h did not produce any significant quantity of new products as well. In particular, no alkylflurophosphates were found in the solutions after storage at elevated temperature. In the absence of either an impurity like alcohol or cathode active material that may (or may not) act as a catalyst, there is no evidence of thermally induced reaction between LiPF 6 and the prototypical Li-ion battery solvents EC, PC, DMC or EMC.

Biocompatible polyurethane/thiacalix[4]arenes functionalized Fe3O4 magnetic nanocomposites: Synthesis and properties.

PubMed

Mohammadi, Abbas; Barikani, Mehdi; Lakouraj, Moslem Mansour

2016-09-01

In this study, a series of magnetic polyurethane/Fe3O4 elastomer nanocomposites were prepared by covalently embedding novel thiacalix[4]arenes (TC4As) functionalized Fe3O4 nanoparticles (TC4As-Fe3O4) which contain macrocycles with reactive hydroxyl groups. Surface functionalization of Fe3O4 nanoparticles with TC4As macrocycles as unique reactive surface modifier not only gives specific characteristics to Fe3O4 nanoparticles but also improves the interphase interaction between nanoparticles and the polyurethane matrices through covalent attachment of polymer chains to nanoparticle surfaces. The novel synthesized TC4As-Fe3O4 nanoparticles were characterized by FTIR, XRD, TGA, VSM and SEM analysis. Furthermore, the effect of functionalization of Fe3O4 nanoparticles on the various properties of resulting nanocomposites was studied by XRD, TGA, DMTA, SEM, and a universal tensile tester. It was found that the functionalization of nanoparticles with TC4As affords better mechanical and thermal properties to polyurethane nanocomposites in comparison with unmodified nanoparticles. The SEM analysis showed finer dispersion of TC4As-Fe3O4 nanoparticles than unmodified Fe3O4 nanoparticles within the polyurethane matrices, which arising from formation of covalent bonding between TC4As functionalized Fe3O4 nanoparticles and polyurethane matrices. Moreover, the investigation of in vitro biocompatibility of novel nanocomposites showed that these samples are excellent candidate for biomedical use. Copyright © 2016 Elsevier B.V. All rights reserved.

Thermal Decomposition Model Development of EN-7 and EN-8 Polyurethane Elastomers.

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

Keedy, Ryan Michael; Harrison, Kale Warren; Cordaro, Joseph Gabriel

Thermogravimetric analysis - gas chromatography/mass spectrometry (TGA- GC/MS) experiments were performed on EN-7 and EN-8, analyzed, and reported in [1] . This SAND report derives and describes pyrolytic thermal decomposition models for use in predicting the responses of EN-7 and EN-8 in an abnormal thermal environment.

Diagnostics for the Analysis of Surface Chemistry Effects on Composite Energetic Material Reactions

DTIC Science & Technology

2015-10-30

integration time) and a NETZSCH STA 449 Jupiter that will allow for consistency and efficiency with its automatic 20 sample changer. (2) Together these...Purchase of the NETZSCH STA 449 Jupiter (DSC-TGA) to resolve reaction kinetics under equilibrium conditions. Images of this instrumentation are included in

Oleic acid coated magnetic nano-particles: Synthesis and characterizations

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

Panda, Biswajit, E-mail: bpanda@mes.ac.in; Goyal, P. S.

2015-06-24

Magnetic nano particles of Fe{sub 3}O{sub 4} coated with oleic acid were synthesized using wet chemical route, which involved co-precipitation of Fe{sup 2+} and Fe{sup 3+} ions. The nano particles were characterized using XRD, TEM, FTIR, TGA and VSM. X-ray diffraction studies showed that nano particles consist of single phase Fe{sub 3}O{sub 4} having inverse spinel structure. The particle size obtained from width of Bragg peak is about 12.6 nm. TEM analysis showed that sizes of nano particles are in range of 6 to 17 nm with a dominant population at 12 - 14 nm. FTIR and TGA analysis showed that -COOH groupmore » of oleic acid is bound to the surface of Fe{sub 3}O{sub 4} particles and one has to heat the sample to 278° C to remove the attached molecule from the surface. Further it was seen that Fe{sub 3}O{sub 4} particles exhibit super paramagnetism with a magnetization of about 53 emu/ gm.« less

Kenaf bast cellulosic fibers hierarchy: a comprehensive approach from micro to nano.

PubMed

Karimi, Samaneh; Tahir, Paridah Md; Karimi, Ali; Dufresne, Alain; Abdulkhani, Ali

2014-01-30

Cellulosic fibers from kenaf bast were isolated in three distinct stages. Initially raw kenaf bast fibers were subjected to an alkali pulping process. Then pulped fibers undergone a bleaching process and finally both pulped and bleached fibers were separated into their constituent nanoscale cellulosic fibers by mechanical shearing. The influence of each treatment on the chemical composition of fibers was investigated. Moreover morphology, functional groups, crystallinity, and thermal behavior of fiber hierarchy at different stages of purification were studied using scanning and transmission electron microscopies, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and thermogravimetric analysis (TGA), respectively. Microscopy studies revealed that applied procedures successfully isolated nanoscale cellulosic fibers from both unbleached and bleached pulps. Chemical composition analysis and FTIR spectroscopy showed that lignin and hemicellulose were almost entirely removed by the applied treatments. XRD and TGA analyses demonstrated progressive enhancement of properties in fibers, hierarchically, in going from micro to nano scale. Interestingly no significant evolution was observed between obtained data of characterized ubnleached and bleached nanofibers. Copyright © 2013 Elsevier Ltd. All rights reserved.

Effect of blowing agents on the oxidation resistance of carbon foams prepared from molten sucrose

NASA Astrophysics Data System (ADS)

Narasimman, R.; Prabhakaran, K.

2013-06-01

We have prepared low density carbon foams from molten sucrose using aluminium nitrate and boric acid blowing agents. A comparative study of the oxidation resistance of the carbon foams prepared using the two blowing agents are reported in the present paper. Oxidation of the carbon foams was evaluated under isothermal and non-isothermal conditions in air atmosphere using thermogravimetric analysis (TGA). We have observed that the alumina produced from the aluminium nitrate blowing agent acts as a catalyst whereas the boron produced from boric acid inhibits the oxidation of the carbon foams. The oxidation resistance of carbon foams increases with boron concentration. The oxidation onset temperature for the carbon foams prepared using boric acid blowing agent was nearly 60°C higher than that prepared using aluminium nitrate blowing agent. Carbon foams prepared using aluminium nitrate blowing agent undergoes complete oxidation at temperature less than 700°C. Whereas that prepared using boric acid blowing agent leave ˜ 50 wt.% residue at 900°C. Further evidence is provided by the kinetic analysis of the TGA using Coats-Redfern (CR) equation.

Microstructural and thermal properties of pure BaFe{sub 12}O{sub 19} and Sr doped barium ferrite (Ba{sub 0.9}Sr{sub 0.1}Fe{sub 12}O{sub 19}) synthesized by auto combustion method

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

Taufeeq, Saba, E-mail: sabataufeeq23@gmail.com; Parveen, Azra; Agrawal, Shraddha

2016-05-23

Nanoparticles (NPs) of Pure BaFe{sub 12}O{sub 19} and Strontium doped Barium Ferrite (Ba{sub 0.9}Sr{sub 0.1}Fe{sub 12}O{sub 19}) have been successfully synthesized by Auto combustion method using citric acid as a chelating agent and calcined at 450°C for 3 hrs and 850°C for 4 hrs. Microstructural studies were carried by XRD and SEM techniques. Structural studies suggest that the crystal system remains hexagonal even with the doping of Strontium. The XRD analysis confirms the formation of the structures in the nanometer regime and the peaks are the evidence of the crystalline phase. The SEM images shows the morphology of surface ofmore » the samples. The thermal property studied by TGA shows the weight loss which is with varying the temperature and weight loss also varies with Sr doping. The TGA analysis exhibits the loss of weight at different temperatures.« less

Synthesis and characterization of polyurethane/CdS-SiO 2 nanocomposites via ultrasonic process

NASA Astrophysics Data System (ADS)

Chen, Jing; Zhou, Yu-Ming; Nan, Qiu-Li; Ye, Xiao-Yun; Sun, Yan-Qing; Wang, Zhi-Qiang; Zhang, Shi-Ming

2008-12-01

In this study, the high-intensity ultrasound was applied in the preparation of chiral polyurethane/CdS-SiO 2 nanocomposites. The polyurethane/CdS-SiO 2 nanocomposites were analyzed by powder X-ray diffraction, thermogravimetric analysis (TGA), TEM and SEM. The results indicated that the heat stability of the nanocomposites was improved in the presence of CdS-SiO 2 core-shell nanoparticles. The infrared emissivity (8-14 μm) study revealed that the nanocomposites possessed much lower infrared values compared with those of the neat polymers and nanoparticles, respectively. A possible mechanism of ultrasonic induced composite reaction was proposed based on the experimental results.

Trace Gas Analyzer (TGA) program

NASA Technical Reports Server (NTRS)

1977-01-01

The design, fabrication, and test of a breadboard trace gas analyzer (TGA) is documented. The TGA is a gas chromatograph/mass spectrometer system. The gas chromatograph subsystem employs a recirculating hydrogen carrier gas. The recirculation feature minimizes the requirement for transport and storage of large volumes of carrier gas during a mission. The silver-palladium hydrogen separator which permits the removal of the carrier gas and its reuse also decreases vacuum requirements for the mass spectrometer since the mass spectrometer vacuum system need handle only the very low sample pressure, not sample plus carrier. System performance was evaluated with a representative group of compounds.

Effective Identification on Adulteration of Polyethylene With Post-consumer Ones

NASA Astrophysics Data System (ADS)

Zhao, S.; Qin, W. B.; Guo, J. F.; Liu, J.; Wang, Y. L.; Zhang, W.; Zhao, X. Y.; Wang, L.

2018-05-01

This paper mainly describes the effective identification of the adulteration of polyethylene with post-consumer ones. Degradation would be happened when multiple processings occurred. The melt flow index (MFI) analysis, thermal gravimetric analysis (TGA), differential scanning calorimeter (DSC) were used to characterize the processability and thermal stabilities of virgin polyethylene and recycled polyethylene which adulterated post-consumer PE. The results indicated that MFI of PE increased with the increasing doping content. Adulterating reclaimed PE had effects on the thermal stability of PE, which led to lower thermal decomposition temperature. Melting peak of recycled LLDPE varied from merely single to double, which differently compared differently with virgin LLDPE. Besides, with the doping content of post-consumer LDPE, the melting temperature had a decreasing tendency.

Relationship Between Habitual Exercise and Performance on Cardiopulmonary Exercise Testing Differs Between Children With Single and Biventricular Circulations.

PubMed

O'Byrne, Michael L; Desai, Sanyukta; Lane, Megan; McBride, Michael; Paridon, Stephen; Goldmuntz, Elizabeth

2017-03-01

Increasing habitual exercise has been associated with improved cardiopulmonary exercise testing (CPET) performance, specifically maximal oxygen consumption in children with operatively corrected congenital heart disease. This has not been studied in children following Fontan palliation, a population in whom CPET performance is dramatically diminished. A single-center cross-sectional study with prospective and retrospective data collection was performed that assessed habitual exercise preceding a clinically indicated CPET in children and adolescents with Fontan palliation, transposition of the great arteries following arterial switch operation (TGA), and normal cardiac anatomy without prior operation. Data from contemporaneous clinical reports and imaging studies were collected. The association between percent predicted VO 2max and habitual exercise duration adjusted for known covariates was tested. A total of 175 subjects (75 post-Fontan, 20 with TGA, and 80 with normal cardiac anatomy) were enrolled. VO 2max was lower in the Fontan group than patients with normal cardiac anatomy (p < 0.0001) or TGA (p < 0.0001). In Fontan subjects, both univariate and multivariate analysis failed to demonstrate a significant association between habitual exercise and VO 2max (p = 0.6), in sharp contrast to cardiac normal subjects. In multivariate analysis, increasing age was the only independent risk factor associated with decreasing VO 2max in the Fontan group (p = 0.003). Habitual exercise was not associated with VO 2max in subjects with a Fontan as compared to biventricular circulation. Further research is necessary to understand why their habitual exercise is ineffective and/or what aspects of the Fontan circulation disrupt this association.

Structure, wettability and thermal degradation of new fluoro-oligomer modified nanoclays.

PubMed

Valsecchi, R; Viganò, M; Levi, M; Turri, S

2008-04-01

Quaternary ammonium salts based on monofunctionalized Perfluoropolyether (PFPE) oligomers were synthesized and used for the cation exchange process of sodium Montmorillonite nanoclays. The new fluoromodified nanoclays were characterized through X-rays diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), termogravimetric analysis (TGA), differential scanning calorimetry (DSC), electronic microscopy (SEM-EDS), and contact angle measurements (CA). In particular XRD showed rather complex patterns (presence of higher order reflections) which allowed the calculation of basal spacings, regularly increasing with the molecular weight of the fluorinated macrocation. Both IR and SEM confirmed the presence of fluorinated segments at clays interface, while TGA showed a limited thermal stability with an onset of degradation temperature which seems not dependent on the molecular weight of the macrocation. CA measurements showed a peculiar behaviour, with evident dynamic hysteresis phenomena and surface tension components quite different from those of commercially available, organomodified clays.

Characterization of urania vaporization with transpiration coupled thermogravimetry

DOE PAGES

McMurray, J. W.

2015-12-05

Determining equilibrium vapor pressures of materials is made easier by transpiration measurements. However, the traditional technique involves condensing the volatiles entrained in a carrier gas outside of the hot measurement zone. One potential problem is deposition en route to a cooled collector. Thermogravimetric analysis (TGA) can be used to measure in situ mass loss due to vaporization and therefore obviate the need to analyze the entire gas train due to premature plating of vapor species. Therefore, a transpiration coupled TGA technique was used to determine equilibrium pressures of UO3 gas over fluorite structure UO2+x and U3O8 at T = (1573more » and 1773) K. Moreover, we compared to calculations from models and databases in the open literature. Our study gives clarity to the thermochemical data for UO3 gas and validates the mass loss transpiration method using thermogravimetry for determining equilibrium vapor pressures of non-stoichiometric oxides.« less

Synthesis, spectral studies and biological evaluation of 2-aminonicotinic acid metal complexes.

PubMed

Nawaz, Muhammad; Abbasi, Muhammad Waseem; Hisaindee, Soleiman; Zaki, Muhammad Javed; Abbas, Hira Fatima; Mengting, Hu; Ahmed, M Arif

2016-05-15

We synthesized 2-aminonicotinic acid (2-ANA) complexes with metals such as Co(II), Fe(III), Ni(II), Mn(II), Zn(II), Ag(I),Cr(III), Cd(II) and Cu(II) in aqueous media. The complexes were characterized and elucidated using FT-IR, UV-Vis, a fluorescence spectrophotometer and thermo gravimetric analysis (TGA). TGA data showed that the stoichiometry of complexes was 1:2 metal/ligand except for Ag(I) and Mn(II) where the ratio was 1:1. The metal complexes showed varied antibacterial, fungicidal and nematicidal activities. The silver and zinc complexes showed highest activity against Bacillus subtilis and Bacillus licheniformis respectively. Fusarium oxysporum was highly susceptible to nickel and copper complexes whereas Macrophomina phaseolina was completely inert to the complexes. The silver and cadmium complexes were effective against the root-knot nematode Meloidogyne javanica. Copyright © 2016 Elsevier B.V. All rights reserved.

An efficient synthesis of graphenated carbon nanotubes over the tailored mesoporous molecular sieves by chemical vapor deposition

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

Atchudan, R.; Department of Chemistry, CEG Campus, Anna University, Chennai 600025; Joo, Jin., E-mail: joojin@knu.ac.kr

2013-06-01

Highlights: ► Tailored 3D cubic Ni/KIT-6 with large pores was synthesized successfully. ► The new hybrid g-CNTs in large scale were synthesized using Ni/KIT-6 by CVD method. ► The use of mesoporous material by CVD method would be an ideal choice to prepare g-CNTs at reasonable cost. ► This type of g-CNTs might be a new avenue for nano-electronic applications. - Abstract: The new hybrid of graphenated carbon nanotubes (g-CNTs) was superior to either CNTs or graphene. Mesoporous 3D cubic Ni/KIT-6 were synthesized hydrothermally through organic template route and then were used as catalytic template for the production of g-CNTsmore » using acetylene as a carbon precursor by chemical vapor deposition (CVD) method. The deposited new hybrid carbon materials were purified and analyzed by various physico-chemical techniques such as XRD, TGA, SEM, TEM and Raman spectroscopy techniques. The graphitization of CNTs was confirmed by TGA and HRTEM studies. Thermal stability, surface morphology, and structural morphology of these materials were revealed by TGA, SEM and TEM analysis, respectively. Moreover, the tailored mesoporous Ni/KIT-6 molecular sieves were found to possess better quality and massive quantity of g-CNTs produced compared to other catalytic template route.« less

Enhanced production of bacterial cellulose by using a biofilm reactor and its material property analysis

PubMed Central

Cheng, Kuan-Chen; Catchmark, Jeff M; Demirci, Ali

2009-01-01

Bacterial cellulose has been used in the food industry for applications such as low-calorie desserts, salads, and fabricated foods. It has also been used in the paper manufacturing industry to enhance paper strength, the electronics industry in acoustic diaphragms for audio speakers, the pharmaceutical industry as filtration membranes, and in the medical field as wound dressing and artificial skin material. In this study, different types of plastic composite support (PCS) were implemented separately within a fermentation medium in order to enhance bacterial cellulose (BC) production by Acetobacter xylinum. The optimal composition of nutritious compounds in PCS was chosen based on the amount of BC produced. The selected PCS was implemented within a bioreactor to examine the effects on BC production in a batch fermentation. The produced BC was analyzed using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), thermogravimetric analysis (TGA), and dynamic mechanical analysis (DMA). Among thirteen types of PCS, the type SFYR+ was selected as solid support for BC production by A. xylinum in a batch biofilm reactor due to its high nitrogen content, moderate nitrogen leaching rate, and sufficient biomass attached on PCS. The PCS biofilm reactor yielded BC production (7.05 g/L) that was 2.5-fold greater than the control (2.82 g/L). The XRD results indicated that the PCS-grown BC exhibited higher crystallinity (93%) and similar crystal size (5.2 nm) to the control. FESEM results showed the attachment of A. xylinum on PCS, producing an interweaving BC product. TGA results demonstrated that PCS-grown BC had about 95% water retention ability, which was lower than BC produced within suspended-cell reactor. PCS-grown BC also exhibited higher Tmax compared to the control. Finally, DMA results showed that BC from the PCS biofilm reactor increased its mechanical property values, i.e., stress at break and Young's modulus when compared to the control BC. The results clearly demonstrated that implementation of PCS within agitated fermentation enhanced BC production and improved its mechanical properties and thermal stability. PMID:19630969

D-TRANSPOSITION OF THE GREAT ARTERIES: Hot Topics in the Current Era of the Arterial Switch Operation

PubMed Central

Villafañe, Juan; Lantin-Hermoso, M. Regina; Bhatt, Ami B.; Tweddell, James S.; Geva, Tal; Nathan, Meena; Elliott, Martin J.; Vetter, Victoria L.; Paridon, Stephen M.; Kochilas, Lazaros; Jenkins, Kathy J.; Beekman, Robert H.; Wernovsky, Gil; Towbin, Jeffrey A.

2015-01-01

Objectives This paper aims to update clinicians on “Hot Topics” in the management of patients with d-transposition of the great arteries (D-TGA) in the current surgical era. Background The arterial switch operation (ASO) has replaced atrial switch procedures for D-TGA and 90% of patients now reach adulthood. Methods The Adult Congenital and Pediatric Cardiology Council (ACPC) of the American College of Cardiology assembled a team of experts to summarize current knowledge on genetics, prenatal diagnosis, surgical timing, balloon atrial septostomy (BAS), prostaglandin therapy (PGE), intraoperative techniques, imaging, coronary obstruction, arrhythmias, sudden death, aortic dilation and regurgitation (AR), neurodevelopmental (ND) issues and lifelong care of D-TGA patients. Results In simple D-TGA, 1) familial recurrence risk is low; 2) children diagnosed prenatally have improved cognitive skills compared with those diagnosed postnatally; 3) echocardiography helps to identify risk factors; 4) routine use of BAS and PGE may not be beneficial in some cases; 5) early ASO improves outcomes and reduces costs with a low mortality. Single or intramural coronary arteries remain risk factors; 6) post-ASO arrhythmias and cardiac dysfunction should raise suspicion of coronary insufficiency; 7) coronary insufficiency and arrhythmias are rare but associated with sudden death; 8) early and late-onset ND abnormalities are common; 9) AR and aortic root dilation are well tolerated; and 10) the aging ASO patient may benefit from “exercise-prescription” rather than restriction. Conclusions Significant strides have been made in understanding risk factors for cardiac, ND and other important clinical outcomes after ASO. PMID:25082585

Combined Effect of Ultrasound Stimulations and Autoclaving on the Enhancement of Antibacterial Activity of ZnO and SiO₂/ZnO Nanoparticles.

PubMed

Rokbani, Hajer; Daigle, France; Ajji, Abdellah

2018-02-25

This study investigates the antibacterial activity (ABA) of suspensions of pure ZnO nanoparticles (ZnO-NPs) and mesoporous silica doped with ZnO (ZnO-UVM7), as well as electrospun nanofibers containing those nanoparticles. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of these two materials were also determined under the same conditions. The results showed a concentration-dependent effect of antibacterial nanoparticles on the viability of Escherichia coli ( E. coli ). Moreover, the combination of the stimulations and sterilization considerably enhanced the antimicrobial activity (AMA) of the ZnO suspensions. Poly (lactic acid) (PLA) solutions in 2,2,2-trifluoroethanol (TFE) were mixed with different contents of nanoparticles and spun into nonwoven mats by the electrospinning process. The morphology of the mats was analyzed by scanning electron microscopy (SEM). The amount of nanoparticles contained in the mats was determined by thermogravimetric analysis (TGA). The obtained PLA-based mats showed a fibrous morphology, with an average diameter ranging from 350 to 450 nm, a porosity above 85%, but with the nanoparticles agglomeration on their surface. TGA analysis showed that the loss of ZnO-NPs increased with the increase of ZnO-NPs content in the PLA solutions and reached 79% for 1 wt % of ZnO-NPs, which was mainly due to the aggregation of nanoparticles in solution. The ABA of the obtained PLA mats was evaluated by the dynamic method according to the ASTM standard E2149. The results showed that, above an optimal concentration, the nanoparticle agglomeration reduced the antimicrobial efficiency of PLA mats. These mats have potential features for use as antimicrobial food packaging material.

Combined Effect of Ultrasound Stimulations and Autoclaving on the Enhancement of Antibacterial Activity of ZnO and SiO2/ZnO Nanoparticles

PubMed Central

Rokbani, Hajer; Ajji, Abdellah

2018-01-01

This study investigates the antibacterial activity (ABA) of suspensions of pure ZnO nanoparticles (ZnO-NPs) and mesoporous silica doped with ZnO (ZnO-UVM7), as well as electrospun nanofibers containing those nanoparticles. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of these two materials were also determined under the same conditions. The results showed a concentration-dependent effect of antibacterial nanoparticles on the viability of Escherichia coli (E. coli). Moreover, the combination of the stimulations and sterilization considerably enhanced the antimicrobial activity (AMA) of the ZnO suspensions. Poly (lactic acid) (PLA) solutions in 2,2,2-trifluoroethanol (TFE) were mixed with different contents of nanoparticles and spun into nonwoven mats by the electrospinning process. The morphology of the mats was analyzed by scanning electron microscopy (SEM). The amount of nanoparticles contained in the mats was determined by thermogravimetric analysis (TGA). The obtained PLA-based mats showed a fibrous morphology, with an average diameter ranging from 350 to 450 nm, a porosity above 85%, but with the nanoparticles agglomeration on their surface. TGA analysis showed that the loss of ZnO-NPs increased with the increase of ZnO-NPs content in the PLA solutions and reached 79% for 1 wt % of ZnO-NPs, which was mainly due to the aggregation of nanoparticles in solution. The ABA of the obtained PLA mats was evaluated by the dynamic method according to the ASTM standard E2149. The results showed that, above an optimal concentration, the nanoparticle agglomeration reduced the antimicrobial efficiency of PLA mats. These mats have potential features for use as antimicrobial food packaging material. PMID:29495334

Impact Strength and Flexural Properties Enhancement of Methacrylate Silane Treated Oil Palm Mesocarp Fiber Reinforced Biodegradable Hybrid Composites

PubMed Central

Ibrahim, Nor Azowa; Ariffin, Hidayah; Yunus, Wan Md. Zin Wan

2014-01-01

Natural fiber as reinforcement filler in polymer composites is an attractive approach due to being fully biodegradable and cheap. However, incompatibility between hydrophilic natural fiber and hydrophobic polymer matrix restricts the application. The current studies focus on the effects of incorporation of silane treated OPMF into polylactic acid (PLA)/polycaprolactone (PCL)/nanoclay/OPMF hybrid composites. The composites were prepared by melt blending technique and characterize the composites with Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). FTIR spectra indicated that peak shifting occurs when silane treated OPMF was incorporated into hybrid composites. Based on mechanical properties results, incorporation of silane treated OPMF enhances the mechanical properties of unmodified OPMF hybrid composites with the enhancement of flexural and impact strength being 17.60% and 48.43%, respectively, at 10% fiber loading. TGA thermogram shows that incorporation of silane treated OPMF did not show increment in thermal properties of hybrid composites. SEM micrographs revealed that silane treated OPMF hybrid composites show good fiber/matrix adhesion as fiber is still embedded in the matrix and no cavity is present on the surface. Water absorption test shows that addition of less hydrophilic silane treated OPMF successfully reduces the water uptake of hybrid composites. PMID:25254230

Chemical modification of magnetite nanoparticles and preparation of acrylic-base magnetic nanocomposite particles via miniemulsion polymerization

NASA Astrophysics Data System (ADS)

Mahdieh, Athar; Mahdavian, Ali Reza; Salehi-Mobarakeh, Hamid

2017-03-01

Nowadays, magnetic nanocomposite particles have attracted many interests because of their versatile applications. A new method for chemical modification of Fe3O4 nanoparticles with polymerizable groups is presented here. After synthesis of Fe3O4 nanoparticles by co-precipitation method, they were modified sequentially with 3-aminopropyl triethoxysilane (APTES), acryloyl chloride (AC) and benzoyl chloride (BC) and all were characterized by FTIR, XRD, SEM and TGA analyses. Then the modified magnetite nanoparticles with unsaturated acrylic groups were copolymerized with methyl methacrylate (MMA), butyl acrylate (BA) and acrylic acid (AA) through miniemulsion polymerization. Although several reports exist on preparation of magnetite-base polymer particles, but the efficiency of magnetite encapsulationwith reasonable content and obtaining final stable latexes with limited aggregation ofFe3O4 are still important issues. These were considered here by controlling reaction parameters. Hence, a seriesofmagneticnanocomposites latex particlescontaining different amounts of Fe3O4 nanoparticles (0-10 wt%) were prepared with core-shell morphology and diameter below 200 nm and were characterized by FT-IR, DSC and TGA analyses. Their morphology and size distribution were studied by SEM, TEM and DLS analyses too. Magnetic properties of all products were also measuredby VSM analysis and the results revealed almost superparamagnetic properties for the obtained nanocomposite particles.

Impact strength and flexural properties enhancement of methacrylate silane treated oil palm mesocarp fiber reinforced biodegradable hybrid composites.

PubMed

Eng, Chern Chiet; Ibrahim, Nor Azowa; Zainuddin, Norhazlin; Ariffin, Hidayah; Yunus, Wan Md Zin Wan

2014-01-01

Natural fiber as reinforcement filler in polymer composites is an attractive approach due to being fully biodegradable and cheap. However, incompatibility between hydrophilic natural fiber and hydrophobic polymer matrix restricts the application. The current studies focus on the effects of incorporation of silane treated OPMF into polylactic acid (PLA)/polycaprolactone (PCL)/nanoclay/OPMF hybrid composites. The composites were prepared by melt blending technique and characterize the composites with Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). FTIR spectra indicated that peak shifting occurs when silane treated OPMF was incorporated into hybrid composites. Based on mechanical properties results, incorporation of silane treated OPMF enhances the mechanical properties of unmodified OPMF hybrid composites with the enhancement of flexural and impact strength being 17.60% and 48.43%, respectively, at 10% fiber loading. TGA thermogram shows that incorporation of silane treated OPMF did not show increment in thermal properties of hybrid composites. SEM micrographs revealed that silane treated OPMF hybrid composites show good fiber/matrix adhesion as fiber is still embedded in the matrix and no cavity is present on the surface. Water absorption test shows that addition of less hydrophilic silane treated OPMF successfully reduces the water uptake of hybrid composites.

Evaporation-based method for preparing gelatin foams with aligned tubular pore structures.

PubMed

Frazier, Shane D; Srubar, Wil V

2016-05-01

Gelatin-based foams with aligned tubular pore structures were prepared via liquid-to-gas vaporization of tightly bound water in dehydrated gelatin hydrogels. This study elucidates the mechanism of the foaming process by investigating the secondary (i.e., helical) structure, molecular interactions, and water content of gelatin films before and after foaming using X-ray diffraction, Fourier transform infrared (FTIR) spectroscopy, differential scanning calorimetry and thermogravimetric analysis (TGA), respectively. Experimental data from gelatin samples prepared at various gelatin-to-water concentrations (5-30 wt.%) substantiate that resulting foam structures are similar in pore diameter (approximately 350 μm), shape, and density (0.05-0.22 g/cm(3)) to those fabricated using conventional methods (e.g., freeze-drying). Helical structures were identified in the films but were not evident in the foamed samples after vaporization (~150 °C), suggesting that the primary foaming mechanism is governed by the vaporization of water that is tightly bound in secondary structures (i.e., helices, β-turns, β-sheets) that are present in dehydrated gelatin films. FTIR and TGA data show that the foaming process leads to more disorder and reduced hydrogen bonding to hydroxyl groups in gelatin and that no thermal degradation of gelatin occurs before or after foaming. Copyright © 2016 Elsevier B.V. All rights reserved.

Influence of blood lipids on global coagulation test results.

PubMed

Kim, Jung-Ah; Kim, Ji-Eun; Song, Sang Hoon; Kim, Hyun Kyung

2015-01-01

High levels of blood lipids have been associated with high levels of coagulation factors. We investigated whether blood lipids influence the results of global coagulation tests, including prothrombin time (PT), activated partial thromboplastin time (aPTT), and thrombin generation assay (TGA). PT, aPTT, and TGA, along with procoagulant and anticoagulant factors, were measured in 488 normal individuals. Vitamin K status was assessed with prothrombin-induced by vitamin K absence-II (PIVKA-II). The procoagulant factors II, VII, IX, X, and XI and anticoagulant factors protein C and protein S showed significant correlations with triglyceride, and the procoagulant factors II, V, VII, IX, X, XI, and XII and anticoagulant factors antithrombin and protein C correlated with total cholesterol. There were no correlations of blood lipid levels with PIVKA-II levels. Subjects with high triglyceride levels (≥200 mg/dL) showed shorter PT values than those with lower triglyceride levels. However, aPTT value was not changed in terms of blood lipid levels. In both 1 and 5 pM tissue factor-induced TGAs, subjects in the high-triglyceride or high-cholesterol groups (≥240 mg/dL) had high levels of lag time, time-to-peak, and endogenous thrombin potential. Total cholesterol was a significant determinant of PT and TGA values. High blood lipids were related with increased coagulation activity in a normal population. Our findings are expected to help interpret the global coagulation test results in individuals with high lipid levels.

Crystallization of Nanocomposite Glasses Made by the SSG Process

DTIC Science & Technology

1993-01-12

thermogravimetric analysis (TGA). The role of glass structure and composition in the thermochemical stability will be discussed. 37 II. EXPERIMENTAL PROCEDLRES The...applications in the materials field. tion and r-plot analysis of this porous nanocomposite showed Because of the nanoscale mixing of inorganic and organic a... nanoparticles in There is a need for substrates with very low relative permit- magnetic recording media can lead to smaller storage units tivitv 1ɛ) in %ery

Rapid determination of melamine in milk using water-soluble CdTe quantum dots as fluorescence probes.

PubMed

Zhang, Minwei; Ping, Hong; Cao, Xianyi; Li, Hongkun; Guan, Fengrui; Sun, Chunyan; Liu, Jingbo

2012-01-01

Water-soluble CdTe quantum dots of different sizes capped with thioglycolic acid (TGA-CdTe QDs) were synthesised via a microwave-assisted method. It was found that melamine could quench the fluorescence emission of TGA-CdTe QDs in aqueous solution. Based on this, a novel method for the determination of melamine has been developed. Under optimum conditions, the fluorescence intensity of TGA-CdTe QDs versus melamine concentrations gave a linear response according to the Stern-Volmer equation. The proposed method has been successfully used to detect melamine in liquid milk with a detection limit of 0.04 mg L⁻¹, and the whole process including sample pre-treatment could be accomplished within 30 min. The obvious merits provided by this method, such as simplicity, rapidity, low cost and high sensitivity would make it promising for on-site screening of melamine adulterant in milk products. The possible mechanism involved in the interaction of melamine with TGA-CdTe QDs is discussed.

Characterization and Transcriptional Profile of Genes Involved in Glycoalkaloid Biosynthesis in New Varieties of Solanum tuberosum L.

PubMed

Mariot, Roberta Fogliatto; de Oliveira, Luisa Abruzzi; Voorhuijzen, Marleen M; Staats, Martijn; Hutten, Ronald C B; van Dijk, Jeroen P; Kok, Esther J; Frazzon, Jeverson

2016-02-03

Before commercial release, new potato (Solanum tuberosum) varieties must be evaluated for content of toxic compounds such as glycoalkaloids (GAs), which are potent poisons. GA biosynthesis proceeds via the cholesterol pathway to α-chaconine and α-solanine. The goal of this study was to evaluate the relationship between total glycoalkaloid (TGA) content and the expression of GAME, SGT1, and SGT3 genes in potato tubers. TGA content was measured by HPLC-MS, and reverse transcription quantitative polymerase chain reactions were performed to determine the relative expression of GAME, SGT1, and SGT3 genes. We searched for cis-elements of the transcription start site using the PlantPAN database. There was a relationship between TGA content and the relative expression of GAME, SGT1, and SGT3 genes in potato tubers. Putative promoter regions showed the presence of several cis-elements related to biotic and abiotic stresses and light. These findings provide an important step toward understanding TGA regulation and variation in potato tubers.

Long-term memory following transient global amnesia: an investigation of episodic and semantic memory.

PubMed

Guillery-Girard, B; Quinette, P; Desgranges, B; Piolino, P; Viader, F; de la Sayette, V; Eustache, F

2006-11-01

Several studies noted persistence of memory impairment following an episode of transient global amnesia (TGA) with standard tests. To specify long-term memory impairments in a group of patients selected with stringent criteria. Both retrograde and anterograde memory were investigated in 32 patients 13-67 months after a TGA episode with original tasks encompassing retrograde semantic memory (academic, public and personal knowledge), retrograde episodic memory (autobiographical events) and anterograde episodic memory. Patients had preserved academic and public knowledge. Pathological scores were obtained in personal verbal fluency for the two most recent periods, and patients produced less autobiographical events than controls. However, when they were provided time to detail, memories were as episodic as in controls regardless of their remoteness. Anterograde episodic tasks revealed a mild but significant impairment of the capacity of re-living the condition of encoding, i.e. the moment at which words were presented. Patients who have suffered from an episode of TGA manifest deficits of memory focused on the retrieval of both recent semantic information and episodic memories and especially the capacity of re-living. These deficits may not result from a deterioration of memory per se but rather from difficulties in accessing memories.

Synthesis, photoluminescence and Magnetic properties of iron oxide (α-Fe2O3) nanoparticles through precipitation or hydrothermal methods

NASA Astrophysics Data System (ADS)

Lassoued, Abdelmajid; Lassoued, Mohamed Saber; Dkhil, Brahim; Ammar, Salah; Gadri, Abdellatif

2018-07-01

In this work the iron oxide (α-Fe2O3) nanoparticles are synthesized using two different methods: precipitation and hydrothermal. Size, structural, optical and magnetic properties were determined and compared using X-ray diffraction (XRD), Transmission Electron Microscopy (TEM), Scanning Electron Microscopy (SEM), Fourier Transform Infra-Red (FT-IR), Raman spectroscopy, Differential Thermal Analysis (DTA), Thermogravimetric Analysis (TGA), Ultraviolet-Visible (UV-Vis) analysis, Superconducting QUantum Interference Device (SQUID) magnetometer and Photoluminescence (PL). XRD data further revealed a rhombohedral (hexagonal) structure with the space group (R-3c) and showed an average size of 21 nm for hydrothermal samples and 33 nm for precipitation samples which concorded with TEM and SEM images. FT-IR confirms the phase purity of the nanoparticles synthesized. The Raman spectroscopy was used not only to prove that we have synthesized pure α-Fe2O3 but also to identify their phonon modes. The TGA showed three mass losses, whereas DTA resulted in three endothermic peaks. The decrease in the particle size of hematite of 33 nm for precipitation samples to 21 nm for hydrothermal samples is responsible for increasing the optical band gap of 1.94-2.10 eV where, the relation between them is inverse relationship. The products exhibited the attractive magnetic properties with good saturation magnetization, which were examined by a SQUID magnetometer. Photoluminescence measurements showed a strong emission band at 450 nm. Pure hematite prepared by hydrothermal method has smallest size, best crystallinity, highest band gap and best value of saturation magnetization compared to the hematite elaborated by the precipitation method.

Characterization of Water and CO2 Adsorption by Stores 3A Desiccant Samples Using Thermal Gravimetric Analysis and Fourier Transform Infrared Spectroscopy

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

RIVERA, DION A.; ALAM, M. KATHLEEN; MARTIN, LAURA

2003-02-01

Two lots of manufactured Type 3a zeolite samples were compared by TGA/IR analysis. The first lot, obtained from Davidson Chemical, a commercial vendor, was characterized during the previous study cycle for its water and water-plus-CO{sub 2} uptake in order to determine whether CO{sub 2} uptake prevented water adsorption by the zeolite. It was determined that CO{sub 2} did not hamper water adsorption using the Davidson zeolite. CO{sub 2} was found on the zeolite surface at dewpoints below -40 C, however it was found to be reversibly adsorbed. During the course of the previous studies, chemical analyses revealed that the Davidsonmore » 3a zeolite contained calcium in significant quantities, along with the traditional counterions potassium and sodium. Chemical analysis of a Type 3a zeolite sample retrieved from Kansas City (heretofore referred to as the ''Stores 3a'' sample) indicated that the Stores sample was a more traditional Type 3a zeolite, containing no calcium. TGA/IR studies this year focused on obtaining CO{sub 2} and water absorbance data from the Stores 3a zeolite. Within the Stores 3a sample, CO{sub 2} was found to be reversibly absorbed within the sample, but only at and below -60 C with 5% CO{sub 2} loading. The amount of CO{sub 2} observed eluting from the Stores zeolite at this condition was similar to what was observed from the Davidson zeolite sample but with a greater uncertainty in the measured value. The results of the Stores 3a studies are summarized within this report.« less

Physiochemical/Rheological Control of Nonmetallic Materials.

DTIC Science & Technology

1982-08-01

CONCLUSIONS ... .. .. . .oo.. .. .. .. .. .. .. .... 23 APPENDIX A - Infrared Spectra of Nonmetallic Consumables .. ......... 24 77’. 1SN 7.. Tiii LIST OF...Spectrometer IR Infrared Spectroscopy GC Gas Chromatrography MS Mass Spectrometry * DSC Differenitial Scanning Calorimetry RT Room Temperature ET Elevated...Linear Heating Rate *FTIR Fourier Transform Infrared TGA Thermogravimetric Analysis Vi 1.0 INTRODUCTION AND SUOARY Over the past 10 years

Collaborative Center in Polymer Photonics

DTIC Science & Technology

2009-02-28

the inorganic residue in the thermogravimetric analysis TGA of the samples, Figure 6. It can be noticed that only approximately 1/3 of the...photonics, nanoparticles , structure, organic-inorganic hybrids, nanocomposites, photonic band gap, plasma-enhanced chemical vapor deposition, discotic liquid...the surface structure of nanoparticles made us focus our study on the morphological and thermodynamic properties of metallic nanoparticles . We cannot

An ultrasensitive SiO2-encapsulated alloyed CdZnSeS quantum dot-molecular beacon nanobiosensor for norovirus.

PubMed

Adegoke, Oluwasesan; Seo, Min-Woong; Kato, Tatsuya; Kawahito, Shoji; Park, Enoch Y

2016-12-15

Ultrasensitive, rapid and selective diagnostic probes are urgently needed to overcome the limitations of traditional probes for norovirus (NV). Here, we report the detection of NV genogroup II via nucleic acid hybridization technology using a quantum dot (QD)-conjugated molecular beacon (MB) probe. To boost the sensitivity of the MB assay system, an ultrasensitive QD fluorophore with unique optical properties was synthesized, characterized and exploited as a fluorescence signal generator. Alloyed thioglycolic (TGA)-capped CdZnSeS QDs with a high photoluminescence (PL) quantum yield (QY) value of 92% were synthesized, and a modified silanization method was employed to encapsulate the thiol-capped QDs in a silica layer. The resulting highly luminescent alloyed SiO2-coated CdZnSeS QDs had a remarkable PL QY value of 98%. Transmission electron microscopy and dynamic light scattering confirmed the monodispersity of the alloyed nanocrystals, and zeta potential analysis confirmed their colloidal stability. Powder X-ray diffraction and PL lifetime measurements confirmed the surface modification of the QDs. The alloyed TGA-capped and SiO2-coated CdZnSeS QD-conjugated MB bioprobes detected extremely low concentrations of NV RNA. Ultrasensitive detection of low concentrations of NV RNA with a limit of detection (LOD) of 8.2copies/mL in human serum and a LOD of 9.3 copies/mL in buffer was achieved using the SiO2-coated CdZnSeS QD-MB probes, an increase in sensitivity of 3-fold compared with the detection limit for NV RNA using TGA-capped CdZnSeS QD-MBs. The additional merits of our detection system are rapidity, specificity and improved sensitivity over conventional molecular test probes. Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.

Effects of Gluten Intake on Risk of Celiac Disease: A Case-Control Study on a Swedish Birth Cohort.

PubMed

Andrén Aronsson, Carin; Lee, Hye-Seung; Koletzko, Sibylle; Uusitalo, Ulla; Yang, Jimin; Virtanen, Suvi M; Liu, Edwin; Lernmark, Åke; Norris, Jill M; Agardh, Daniel

2016-03-01

Early nutrition may affect the risk of celiac disease. We investigated whether amount of gluten in diet until 2 years of age increases risk for celiac disease. We performed a 1-to-3 nested case-control study of 146 cases, resulting in 436 case-control pairs matched for sex, birth year, and HLA genotype generated from Swedish children at genetic risk for celiac disease. Newborns were annually screened for tissue transglutaminase autoantibodies (tTGA). If tested tTGA positive, time point of seroconversion was determined from frozen serum samples taken every 3 months. Celiac disease was confirmed by intestinal biopsies. Gluten intake was calculated from 3-day food records collected at ages 9, 12, 18 and 24 months. Odds ratios (OR) were calculated through conditional logistic regression. Breastfeeding duration (median, 32 wk) and age at first introduction to gluten (median, 22 wk) did not differ between cases and tTGA-negative controls. At the visit before tTGA seroconversion, cases reported a larger intake of gluten than controls (OR, 1.28; 95% confidence interval [CI], 1.13-1.46; P = .0002). More cases than controls were found in the upper third tertile (ie, >5.0 g/d) before they tested positive for tTGA seroconversion than controls (OR, 2.65; 95% CI, 1.70-4.13; P < .0001). This finding was similar in children homozygous for DR3-DQ2 (OR, 3.19; 95% CI, 1.61-6.30; P = .001), heterozygous for DR3-DQ2 (OR, 2.24; 95% CI, 1.08-4.62; P = .030), and for children not carrying DR3-DQ2 (OR, 2.43; 95% CI, 0.90-6.54; P = .079). The amount of gluten consumed until 2 years of age increases the risk of celiac disease at least 2-fold in genetically susceptible children. These findings may be taken into account for future infant feeding recommendations. Copyright © 2016 AGA Institute. Published by Elsevier Inc. All rights reserved.

Preparation and characterization of (St-DVB-MAA) ion exchange resins

NASA Astrophysics Data System (ADS)

Jiang, Shanquan; Sun, Xiangwei; Ling, Lixing; Wang, Shumin; Wu, Wufeng; Cheng, Shihong; Hu, Yue; Zhong, Chunyan

2017-08-01

In this paper, used polyvinyl alcohol as dispersing agent, Benzoyl peroxide as initiator of polymerization, Divinyl benzene as cross-linking agent, Styrene and 2-Methylpropenoic acid as monomer, ion exchange resin (copolymer of St-DVB-MAA)were prepared by suspension polymerization on 80°C. The structures, components and properties of the prepared composite micro gels were characterized by Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA). The experiment of ion exchange was conducted by resin to deal with copper ions in the solution. The result showed that performance of the ion exchange capacity was excellent, which impacted by pH.

Dielectric and transport properties of CaTiO3

NASA Astrophysics Data System (ADS)

Bhadala, Falguni; Suthar, Lokesh; Roy, M.; Jha, Vikash Kumar

2018-05-01

The ceramic sample of CaTiO3 (CTO) has been prepared by standard high temperature solid state reaction method using high purity oxides. The formation of the compound as well as structural analysis has been carried out by X-ray diffraction method. The dielectric constant and dielectric loss as a function of frequency (20kHz-10MHz) and temperature (RT-490K) have been measured. The dc conductivity has been measured and activation energy was calculated using the Arrhenius relation. The Enthalpy change (ΔH), Specific heat and Weight-loss of the compound have been measured using DTA/TGA techniques. The results are discussed in detail.

Thermokinetic analysis and product characterization of Medium Density Fiberboard pyrolysis.

PubMed

Aslan, Dilan Irmak; Özoğul, Buğçe; Ceylan, Selim; Geyikçi, Feza

2018-06-01

This study investigates the pyrolysis of Medium Density Fiberboard (MDF) as a potential waste management solution. Thermal behaviour of MDF was analysed via TG/DSC. The primary decomposition step occurred between 190 °C and 425 °C. Evolved gaseous products over this step were evaluated by a FTIR spectrometer coupled with TGA. Peaks for phenolic, alcohols and aldehydes were detected at the maximum decomposition temperature. Py-GC/MS analysis revealed phenols, ketones and cyclic compounds as the primary non-condensable pyrolysis products. The kinetics of pyrolysis were investigated by the widely applied Distributed Activation Energy Model, resulting in an average activation energy and pre-exponential factor of 127.40 kJ mol -1 and 8.4E+11. The results of this study suggest that pyrolyzing MDF could potentially provide renewable fuels and prevent environmental problems related with MDF disposal. Copyright © 2018 Elsevier Ltd. All rights reserved.

Thermal energy storage characteristics of micro-nanoencapsulated heneicosane and octacosane with poly(methylmethacrylate) shell.

PubMed

Sarı, Ahmet; Alkan, Cemil; Biçer, Alper

2016-05-01

In this study, PMMA/heneicosane (C21) and PMMA/octacosane (C28) micro-nano capsules were fabricated via emulsion polymerisation method. The chemical structures of the fabricated capsules were verified with the FT-IR spectroscopy analysis. The results of POM, SEM and PSD analysis indicated that most of the capsules were consisted of micro/nano-sized spheres with compact surface. The DSC measurements showed that the capsules had melting temperature in the range of about 39-60 °C and latent heat energy storage capacity in the range of about 138-152 J/g. The results of TGA showed that sublimit temperature values regarding the first degradation steps of both capsules were quite over the phase change or working temperatures of encapsulated paraffins. The thermal cycling test exhibited that the capsules had good thermal reliability and chemical stability. Additionally, the prepared capsules had reasonably high thermal conductivity.

ZnO nanoparticles via Moringa oleifera green synthesis: Physical properties & mechanism of formation

NASA Astrophysics Data System (ADS)

Matinise, N.; Fuku, X. G.; Kaviyarasu, K.; Mayedwa, N.; Maaza, M.

2017-06-01

The research work involves the development of better and reliable method for the bio-fabrication of Zinc oxide nanoparticles through green method using Moringa Oleifera extract as an effective chelating agent. The electrochemical activity, crystalline structure, morphology, isothermal behavior, chemical composition and optical properties of ZnO nanoparticles were studied using various characterization techniques i.e. Cyclic voltammetry (CV), X-ray powder diffraction (XRD), High resolution transmission electron microscopy (HRTEM), Selected area electron diffraction (SEAD), Differential scanning calorimetry/thermogravimetric analysis (DSC/TGA), Fourier Transform Infrared analysis (FTIR) and Ultraviolet spectroscopy studies (UV-vis). The electrochemical analysis proved that the ZnO nano has high electrochemical activity without any modifications and therefore are considered as a potential candidate in electrochemical applications. The XRD pattern confirmed the crystallinity and pure phase of the sample. DSC/TGA analysis of ZnO sample (before anneal) revealed three endothermic peaks around 140.8 °C, 223.7 °C and 389.5 °C. These endothermic peaks are attributed to the loss of volatile surfactant, conversion of zinc hydroxide to zinc oxide nanoparticles and transformation of zinc oxide into zinc nanoparticles. Mechanisms of formation of the ZnO nanoparticles via the chemical reaction of the Zinc nitrate precursor with the bioactive compounds of the Moringa oleifera are proposed for each of the major family compounds: Vitamins, Flavonoids, and Phenolic acids.

Free thyroxine concentrations by equilibrium dialysis and chemiluminescent immunoassays in 13 hypothyroid dogs positive for thyroglobulin antibody.

PubMed

Randolph, J F; Lamb, S V; Cheraskin, J L; Schanbacher, B J; Salerno, V J; Mack, K M; Scarlett, J M; Place, N J

2015-01-01

To determine if concentrations of free thyroxine (FT4) measured by semi-automated chemiluminescent immunoassay (CLIA) correspond to FT4 determined by equilibrium dialysis (ED) in hypothyroid dogs positive for thyroglobulin antibody (TGA). Thirteen TGA-positive dogs classified as hypothyroid based on subnormal FT4 concentrations by ED. Qualitative assessment of canine TGA was performed using an enzyme-linked immunosorbent assay. Serum total thyroxine and total triiodothyronine concentrations were measured by radioimmunoassay. Serum FT4 concentration was determined by ED, and also by semi-automated CLIA for human FT4 (FT4h) and veterinary FT4 (FT4v). Canine thyroid stimulating hormone concentration was measured by semi-automated CLIA. Each dog's comprehensive thyroid profile supported a diagnosis of hypothyroidism. For detection of hypothyroidism, sensitivities of CLIA for FT4h and FT4v were 62% (95% CI, 32-85%) and 75% (95% CI, 36-96%), respectively, compared to FT4 by ED. Five of 13 (38%) dogs had FT4h and 2 of 8 (25%) dogs had FT4v concentrations by CLIA that were increased or within the reference range. Percentage of false-negative test results for FT4 by CLIA compared to ED was significantly (P < .0001 for FT4h and P < .001for FT4v) higher than the hypothesized false-negative rate of 0%. Caution should be exercised in screening dogs for hypothyroidism using FT4 measured by CLIA alone. Some (25-38%) TGA-positive hypothyroid dogs had FT4 concentrations determined by CLIA that did not support a diagnosis of hypothyroidism. Copyright © 2015 The Authors. Journal of Veterinary Internal Medicine published by Wiley Periodicals, Inc. on behalf of the American College of Veterinary Internal Medicine.

Theoretical Study of the Oxidation Behavior of Precipitation Hardening Steel

NASA Astrophysics Data System (ADS)

Pistofidis, N.; Vourlias, G.; Psyllaki, P.; Chrissafis, K.

2010-01-01

The oxidation of precipitation hardening (PH) steels is a rather unexplored area. In the present work an attempt is made is made to estimate the kinetics of a PH steel. For this purpose specimens of the material under examination were isothermally heated at 850, 900 and 950° C for 15 hr. Kinetics was based on TGA results. During heating a thick scale is formed on the substrate surface, which is composed by different oxides. The layer close to the substrate is compact and as a result it impedes corrosion. The mathematical analysis of the collected data shows that the change of the mass of the substrate per unit area versus time is described by a parabolic law.

Investigation on Thermal Properties of Kenaf Fibre Reinforced Polyurethane Bio-Composites

NASA Astrophysics Data System (ADS)

Athmalingam, Mathan; Vicki, W. V.

2018-01-01

This research focuses on the effect of Kenaf fibre on thermal properties of Polyurethane (PU) reinforced kenaf bio-composites. The samples were prepared using the polymer casting method with different percentages of kenaf fibre content (5 wt%, 10 wt%, 15 wt%). The thermal properties of Kenaf/PU bio-composite are determined through the Thermogravimetric Analysis and Differential Scanning Calorimeter test. The TGA results revealed that 10 wt% Kenaf/PU bio-composite appeared to be more stable. DSC results show that the glass transition temperature (Tg) value of 10 wt% Kenaf/PU composite is significant to pure polyurethane. It can be said that the thermal stability of 10 wt% Kenaf/PU bio-composite exhibits higher thermal stability compared to other samples.

Properties of alginate fiber spun-dyed with fluorescent pigment dispersion.

PubMed

Wang, Ping; Tawiah, Benjamin; Tian, Anli; Wang, Chunxia; Zhang, Liping; Fu, Shaohai

2015-03-15

Spun-dyed alginate fiber was prepared by the spun-dyeing method with the mixture of fluorescent pigment dispersion and sodium alginate fiber spinning solution, and its properties were characterized by SEM, TGA, DSC, and XRD. The results indicate that fluorescent pigment dispersion prepared with esterified poly (styrene-alt maleic acid) had excellent compatibility with sodium alginate fiber spinning solution, and small amount of fluorescent pigment could reduce the viscosity of spun-dyed spinning solutions. SEM photo of spun-dyed alginate fiber indicated that fewer pigment particles deposited on its surface. TGA, DSC, and XRD results suggested that thermal properties and crystal phase of spun-dyed alginate fibers had slight changes compared to the original alginate fibers. The fluorescence intensity of spun-dyed alginate fiber reached its maximum when the content of fluorescent pigment was 4%. The spun-dyed alginate fiber showed excellent rubbing and washing fastness. Copyright © 2014 Elsevier Ltd. All rights reserved.

Synthesis and Thermal and Photo Behaviors of New Polyamide/Organocaly Nanocomposites Containing Para Phenylenediacrylic Moiety

NASA Astrophysics Data System (ADS)

Faghihi, Khalil; Soleimani, Masoumeh; Shabanian, Meisam; Abootalebi, Ashraf Sadat

2011-06-01

New type of aromatic polyamide/montmorillonite nanocomposites were produced using solution process in N-methyl-2-pyrolidone. Amide chains were synthesized from 4,4'-diaminodiphenyl sulfone and p-phenylenediacrylic acid in N-methyl-2-pyrolidone. The resulting nanocomposite films containing 5-15 mass % of organoclay were characterized for FT-IR, scanning electronmicroscopy (SEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA), optical transparency and water absorption measurements. The distribution of organoclay and nanostructure of the composites were investigated by (XRD) and SEM analyses. Thermogravimetric analysis indicated an increase in thermal stability of nanocomposites as compared to pristine polyamide. The percentage optical transparency and water absorption of these hybrids was found to be much reduced upon the addition of modified layered silicate indicating decreased permeability.

Rapid Response Research and Development (R&D) for the Aerospace Systems Directorate. Delivery Order 0021: Engineering Research and Technical Analyses of Advanced Airbreathing Propulsion Fuels, Subtask: Engine and Pump Studies Utilizing JP-8 and Alcohol-to-Jet (ATJ) Blends

DTIC Science & Technology

2014-08-01

41 Figure A-21. Lubricant Soot Accumulation...ASTM D4739 Total Base Number ASTM D664 Total Acid Number ASTM D445 Kinematic Viscosity @ 100°C ASTM D4052 Density ASTM TGA SOOT TGA Soot ASTM E168...118.85 134.01 145.47 169.22 187.43 342.42 Nitration (Abs./cm) E168 FTIR 0 6.67 10.91 16.54 19.04 25.79 35.12 24.03 23.75 52.31 93.9 Soot (%) Soot TGA

Investment casting using multi-jet modelling patterns: the thermogravimetric analysis of visijet® SR200 UV curable acrylate plastic

NASA Astrophysics Data System (ADS)

Hafsa, M. N.; Ibrahim, M.; Sharif, S.

2013-12-01

Rapid Prototyping (RP) technology is actively studied to be implemented in Investment Casting (IC) process. Nowadays RP techniques are studied for their feasibility as IC master patterns, in terms of pattern collapsibility and drainage during burnout. The purpose of the study is to determine the characteristic of Visijet® SR200 acrylate material during burnout process. Traditional IC patterns made from wax have properties that limit their application in precision casting, especially for parts with thin geometries that readily break or deform when handled or dipped in the refractory slurry. Furthermore, it is not economical when producing a small number of parts. Non wax patterns fabricated for IC process, revealed ceramic shell cracking due to excessive thermal expansions, incomplete collapsibility of pattern during burnout, residual ash and poor surface finish. Thermogravimetric analysis (TGA) was used to measured the weight loss of acrylate material as the temperature was increased. TGA measured the change of material's mass as it is heated. It represents the decomposition temperature after being subjected to varying temperatures, as well as the amount of residual ash. In this experiment, the temperature range was from 20°C to 700°C with 5°C increment. Experiment results show the values of material's optimum reaction temperature and decomposing temperature of Visijet® SR200 acrylate. The percentages of remaining materials were also monitored throughout the process to obtain the amount of residual ash. All of the temperature values obtained is a resemblance for the actual burnout process and can be used as references.

Fast removal of malachite green dye using novel superparamagnetic sodium alginate-coated Fe3O4 nanoparticles.

PubMed

Mohammadi, Abbas; Daemi, Hamed; Barikani, Mehdi

2014-08-01

In this study, superparamagnetic sodium alginate-coated Fe3O4 nanoparticles (Alg-Fe3O4) as a novel magnetic adsorbent were prepared by in situ coprecipitation method, in which Fe3O4 nanoparticles were precipitated from FeCl3 and FeCl2 under alkaline medium in the presence of sodium alginate. The Alg-Fe3O4 nanoparticles were used for removal of malachite green (MG) from aqueous solutions using batch adsorption technique. The characterization of synthesized nanoparticles was performed using XRD, FTIR, TEM, TGA and vibrating sample magnetometer (VSM) techniques. FTIR analysis of synthesized nanoparticles provided the evidence that sodium alginate was successfully coated on the surface of Fe3O4 nanoparticles. The FT-IR and TGA characterization showed that the Alg-Fe3O4 nanoparticles contained about 14% (w/w) of sodium alginate. Moreover, TEM analysis indicated that the average diameter of the Alg-Fe3O4 nanoparticles was about 12nm. The effects of adsorbent dosage, pH and temperature were investigated on the adsorption properties of MG onto Alg-Fe3O4 nanoparticles. The equilibrium adsorption data were modeled using the Langmuir and Freundlich isotherms. The maximum adsorption capacity obtained from Langmuir isotherm equation was 47.84mg/g. The kinetics of adsorption of MG onto Alg-Fe3O4 nanoparticles were investigated using the pseudo-first-order and pseudo-second-order kinetic models. The results showed that the adsorption of MG onto nanoparticles followed pseudo-second-order kinetic model. Copyright © 2014 Elsevier B.V. All rights reserved.

Thermal decomposition of dolomite under CO2: insights from TGA and in situ XRD analysis.

PubMed

Valverde, Jose Manuel; Perejon, Antonio; Medina, Santiago; Perez-Maqueda, Luis A

2015-11-28

Thermal decomposition of dolomite in the presence of CO2 in a calcination environment is investigated by means of in situ X-ray diffraction (XRD) and thermogravimetric analysis (TGA). The in situ XRD results suggest that dolomite decomposes directly at a temperature around 700 °C into MgO and CaO. Immediate carbonation of nascent CaO crystals leads to the formation of calcite as an intermediate product of decomposition. Subsequently, decarbonation of this poorly crystalline calcite occurs when the reaction is thermodynamically favorable and sufficiently fast at a temperature depending on the CO2 partial pressure in the calcination atmosphere. Decarbonation of this dolomitic calcite occurs at a lower temperature than limestone decarbonation due to the relatively low crystallinity of the former. Full decomposition of dolomite leads also to a relatively low crystalline CaO, which exhibits a high reactivity as compared to limestone derived CaO. Under CO2 capture conditions in the Calcium-Looping (CaL) process, MgO grains remain inert yet favor the carbonation reactivity of dolomitic CaO especially in the solid-state diffusion controlled phase. The fundamental mechanism that drives the crystallographic transformation of dolomite in the presence of CO2 is thus responsible for its fast calcination kinetics and the high carbonation reactivity of dolomitic CaO, which makes natural dolomite a potentially advantageous alternative to limestone for CO2 capture in the CaL technology as well as SO2in situ removal in oxy-combustion fluidized bed reactors.

A potential utilization of end-of-life tyres as recycled carbon black in EPDM rubber.

PubMed

Sagar, M; Nibedita, K; Manohar, N; Kumar, K Raj; Suchismita, S; Pradnyesh, A; Reddy, A Babul; Sadiku, E Rotimi; Gupta, U N; Lachit, P; Jayaramudu, J

2018-04-01

End-of-life (EOL) tyres and their decomposition present severe environmental concern due to their resistance to moisture, oxygen, natural degradation, etc. Pyrolysis is considered to be the most effective and sustainable process for recycling, due to its eco-friendly process. The current work studied the effect of recycled carbon black (rCB), obtained from the pyrolysis of EOL tyres, on the properties of ethylene propylene diene rubber (EPDM). The rCB was characterized by scanning electron microscopy (SEM), thermogravimetric analysis (TGA) and chemical methods. rCB was incorporated solely, into a conventional EPDM formulation and also in combination with N550 carbon black. The physico-mechanical properties of the EPDM vulcanizates, before and after aging, were succinctly studied by SEM, TGA, Differential Scanning Calorimetry (DSC), tensile tests and cross-link density. The average particle size of rCB was observed to be 8 µm and the ash content was observed to be higher when compared to the conventional N550 carbon black, which was evident, by the TGA and SEM-EDX analyses. The reinforcing effect and the cross-link density of the rCB-filled vulcanizates were found to be marginally inferior in comparison to the conventional carbon black (N550). The morphology of the tensile- and tear-fractured surfaces were studied by SEM and it was observed that the breaking mechanism follows the rubber chain detachment from the surface mode. Copyright © 2018 Elsevier Ltd. All rights reserved.

Durable Hybrid Coatings. Annual Performance Report (2008)

DTIC Science & Technology

2008-09-01

points 162ensuring stabilization of the reading before moving to the next point. 163Two different thermogravimetric analysis (TGA) methods were...aluminum alloy (Al 2024). Mg-rich primers based on a hybrid organic-inorganic binder derived from silica nanoparticles and...phenethyltrimethoxysilane gave excellent corrosion protection of Al 2024-T3. Work has continued on these coatings with particular emphasis on the silica nanoparticle

The influence of cellulose nanocrystal additions on the performance of cement paste

Treesearch

Yizheng Cao; Pablo Zavaterri; Jeff Youngblood; Robert Moon; Jason Weiss

2015-01-01

The influence of cellulose nanocrystals (CNCs) addition on the performance of cement paste was investigated. Our mechanical tests show an increase in the flexural strength of approximately 30% with only 0.2% volume of CNCs with respect to cement. Isothermal calorimetry (IC) and thermogravimetric analysis (TGA) show that the degree of hydration (DOH) of the cement paste...

Kinetic model of the thermal pyrolysis of chrome tanned leather treated with NaOH under different conditions using thermogravimetric analysis.

PubMed

Bañón, E; Marcilla, A; García, A N; Martínez, P; León, M

2016-02-01

The thermal decomposition of chrome tanned leather before and after a soaking treatment with NaOH was studied using thermogravimetric analysis (TGA). The effect of the solution concentration (0.2M and 0.5M) and the soaking time (5min and 15min) was evaluated. TGA experiments at four heating rates (5, 10, 15 and 20°Cmin(-1)) were run in a nitrogen atmosphere for every treatment condition. A kinetic model was developed considering the effect of the three variables studied, i.e.: the NaOH solution concentration, the soaking time and the heating rate. The proposed model for chrome tanned leather pyrolysis involves a set of four reactions, i.e.: three independent nth order reactions, yielding the corresponding products and one of them undergoing a successive cero order reaction. The model was successfully applied simultaneously to all the experimental data obtained. The evaluation of the kinetic parameters obtained (activation energy, pre-exponential factor and reaction order) allowed a better understanding of the effect of the alkali treatment on these wastes. Copyright © 2015 Elsevier Ltd. All rights reserved.

Investigation of irradiated 1H-Benzo[b]pyrrole by ESR, thermal methods and learning algorithm

NASA Astrophysics Data System (ADS)

Algul, Gulay; Ceylan, Yusuf; Usta, Keziban; Yumurtaci Aydogmus, Hacer; Usta, Ayhan; Asik, Biray

2016-05-01

1H-Benzo[b]pyrrole samples were irradiated in the air with gamma source at 0.969 kGy per hour at room temperature for 24, 48 and 72 h. After irradiation, electron spin resonance, thermogravimetry analysis (TGA) and differential thermal analysis (DTA) measurements were immediately carried out on the irradiated and unirradiated samples. The ESR measurements were performed between 320 and 400 K. ESR spectra were recorded from the samples irradiated for 48 and 72 h. The obtained spectra were observed to be dependent on temperature. Two radical-type centres were detected on the sample. Detected radiation-induced radicals were attributed to R-+•NH and R=•CC2H2. The g-values and hyperfine constants were calculated by means of the experimental spectra. It was also determined from TGA spectrum that both the unirradiated and irradiated samples were decomposed at one step with the rising temperature. Moreover, a theoretical study was presented. Success of the machine learning methods was tested. It was found that bagging techniques, which are widely used in the machine learning literature, could optimise prediction accuracy noticeably.

Synthesis, spectroscopic characterization and structural studies of a new proton transfer (H-bonded) complex of o-phenylenediamine with L-tartaric acid

NASA Astrophysics Data System (ADS)

Khan, Ishaat M.; Ahmad, Afaq

2013-10-01

A proton transfer or H-bonded (CT) complex of o-phenylenediamine (OPD) as donor with L-tartaric acid (TART) as acceptor was synthesized and characterized by spectral techniques such as FTIR, 1H NMR, elemental analysis, TGA-TDA, X-ray crystallography and spectrophotometric studies. The structural investigations exhibit that the cation [OPD+] and anion [TART-] are linked together through strong N+-H⋯O- type hydrogen bonds due to transfer of proton from acceptor to donor. Formed H-bonded complex exhibits well resolved proton transfer bands in the regions where neither donor nor acceptor has any absorption. The stoichiometry of the H-bonded complex (HBC) was found to be 1:1, determined by straight line methods. Spectrophotometric studies have been performed at room temperature and Benesi-Hildebrand equation was used to determine formation constant (KCT), molar extinction coefficient (ɛCT) and also transition energy (ECT) of the H-bonded complex. Spectrophotomeric and crystallographic studies have ascertained the formation of 1:1 H-bonded complex. Thermal analysis (TGA-DTA) was also used to confirm the thermal fragmentation and the stability of the synthesized H-bonded complex.

Synthesis of a Novel Phosphorus-Containing Flame Retardant Curing Agent and Its Application in Epoxy Resins.

PubMed

Zhang, Hongkun; Xu, Miaojun; Li, Bin

2016-03-01

A novel phosphorus-containing compound diphenyl-(2,5-dihydroxyphenyl)-phosphine oxide defined as DPDHPPO was synthesized and used as flame retardant and curing agent for epoxy resins (EP). The chemical structure was well characterized by Fourier transform infrared (FTIR) spectroscopy, 1H, 13C and 31P nuclear magnetic resonance. The flame retardant properties, combusting performances and thermal degradation behaviors of the cured epoxy resins were investigated by limiting oxygen index (LOI), vertical burning tests (UL-94), cone calorimeter and thermogravimetric analysis (TGA) tests. The morphologies and chemical compositions of char residues for cured epoxy resins were investigated by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS), respectively. The water resistant properties were evaluated by putting the samples into distilled water at 70 degrees C for 168 h. The results revealed that the EP/40 wt% DPDHPPO/60 wt% PDA thermosets successfully passed UL-94 V-0 flammability rating and the LOI value was as high as 31.9%. The cone tests results revealed that the incorporation of DPDHPPO efficiently reduced the combustion parameters of epoxy resins thermosets, such as heat release rate (HRR), total heat release (THR) and so on. The TGA results indicated that the introduction of DPDHPPO promoted epoxy resins matrix decomposed ahead of time compared with that of pure EP and led to a higher char yield and thermal stability at high temperature. The morphological structures and analysis of XPS of char residues revealed that DPDHPPO benefited to the formation of a sufficient, compact and homogeneous char layer with rich flame retardant elements on the epoxy resins materials surface during combustion. After water resistance tests, EP/40 wt% DPDHPPO/60 wt% PDA thermosets still remained excellent flame retardancy, the moisture absorption of epoxy resins thermosets decreased with the increase of DPDHPPO contents in the thermosets due to the existing of P-C bonds and the rigid aromatic hydrophobic structure.

Development of quality metrics for ambulatory pediatric cardiology: Transposition of the great arteries after arterial switch operation.

PubMed

Baker-Smith, Carissa M; Carlson, Karina; Ettedgui, Jose; Tsuda, Takeshi; Jayakumar, K Anitha; Park, Matthew; Tede, Nikola; Uzark, Karen; Fleishman, Craig; Connuck, David; Likes, Maggie; Penny, Daniel J

2018-01-01

To develop quality metrics (QMs) for the ambulatory care of patients with transposition of the great arteries following arterial switch operation (TGA/ASO). Under the auspices of the American College of Cardiology Adult Congenital and Pediatric Cardiology (ACPC) Steering committee, the TGA/ASO team generated candidate QMs related to TGA/ASO ambulatory care. Candidate QMs were submitted to the ACPC Steering Committee and were reviewed for validity and feasibility using individual expert panel member scoring according to the RAND-UCLA methodology. QMs were then made available for review by the entire ACC ACPC during an "open comment period." Final approval of each QM was provided by a vote of the ACC ACPC Council. Patients with TGA who had undergone an ASO were included. Patients with complex transposition were excluded. Twelve candidate QMs were generated. Seven metrics passed the RAND-UCLA process. Four passed the "open comment period" and were ultimately approved by the Council. These included: (1) at least 1 echocardiogram performed during the first year of life reporting on the function, aortic dimension, degree of neoaortic valve insufficiency, the patency of the systemic and pulmonary outflows, the patency of the branch pulmonary arteries and coronary arteries, (2) neurodevelopmental (ND) assessment after ASO; (3) lipid profile by age 11 years; and (4) documentation of a transition of care plan to an adult congenital heart disease (CHD) provider by 18 years of age. Application of the RAND-UCLA methodology and linkage of this methodology to the ACPC approval process led to successful generation of 4 QMs relevant to the care of TGA/ASO pediatric patients in the ambulatory setting. These metrics have now been incorporated into the ACPC Quality Network providing guidance for the care of TGA/ASO patients across 30 CHD centers. © 2017 Wiley Periodicals, Inc.

Anatomical factors determining surgical decision-making in patients with transposition of the great arteries with left ventricular outflow tract obstruction.

PubMed

Honjo, Osami; Kotani, Yasuhiro; Bharucha, Tara; Mertens, Luc; Caldarone, Christopher A; Redington, Andrew N; Van Arsdell, Glen

2013-12-01

Transposition of the great arteries (TGA) and left ventricular outflow tract obstruction (LVOTO) with or without ventricular septal defect have multiple surgical treatment options. We sought to identify pre- and intraoperative factors that determine the timing of repair, procedure type and subsequent LVOT outcome. Twenty-eight (8.2% of all TGA) patients with TGA with LVOTO (double outlet ventricle, n = 5, TGA/intact septum, n = 1) between 2000 and 2012 were reviewed. Anatomical factors were identified by prerepair echocardiography. LVOTO complexity was characterized by the degree of obstruction (0 = none, 0.33 = mild, 0.66 moderate and 1 = severe) at various levels: pulmonary valve (PV) dysplasia/hypoplasia, posterior deviation of the infundibular septum, fibromuscular ridge, tissue tag and abnormal chordal attachment. Summation of the obstruction score, at each level, yielded the LVOT complexity score. The descriptive analysis of intraoperative decision-making at late repair was performed. early arterial switch operation (ASO) + LVOT resection (n = 9, 32%), late ASO + LVOT resection (n = 3, 10%), Nikaidoh (n = 8, 29%), Rastelli (n = 6, 21%), single-ventricle palliation (n = 2, 7%). The primary LVOT obstruction mechanism was posterior deviation of the infundibular septum (n = 16, 57%) and PV dysplasia (n = 6, 21%). The early ASO group had a lower PV complexity score (0.42 ± 0.22 vs 0.96 ± 0.55, P = 0.007), tissue tag score (0.03 ± 0.15 vs 0.26 ± 0.34, P = 0.018) and LVOT complexity score (2.11 ± 0.86 vs 3.2 ± 0.96, P = 0.006). The LVOT complexity score in the Nikaidoh group was higher than in the late ASO group (P = 0.019). Of 16 candidates for the Nikaidoh procedure, 6 patients underwent a Rastelli operation due to coronary artery patterns (single coronary, n = 3, 1RL-2Cx, n = 2 or an abnormal left anterior descending coronary artery course, n = 1). Two patients underwent single-ventricle palliation due to the interference of essential chordae. All patients survived the operation. The 3-year survival was 96%. One patient who underwent late ASO required re-LVOT resection. A newly developed scoring system, the LVOT complexity score, helped to quantify the LVOT complexity and was correlated with our choice of the surgical procedure of TGA with LVOTO. The current strategy achieved reasonable survival and LVOT outcome with three quarters of the patients having an anatomically aligned LVOT. The coronary anatomy pattern was the primary determinant in the decision-making between the Nikaidoh procedure and the Rastelli operation.

Crystal growth, structure analysis and characterisation of 2 - (1, 3 - dioxoisoindolin - 2 - yl) acetic acid single crystal

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

Sankari, R. Siva, E-mail: sivasankari.sh@act.edu.in; Perumal, Rajesh Narayana

2014-04-24

Single crystal of dielectric material 2 - (1, 3 - dioxoisoindolin - 2 - yl) acetic acid has been grown by slow evaporation solution growth method. The grown crystal was harvested in 25 days. The crystal structure was analyzed by Single crystal X - ray diffraction. UV-vis-NIR analysis was performed to examine the optical property of the grown crystal. The thermal property of the grown crystal was studied by thermogravimetric analysis (TGA) and differential thermal analysis (DTA). The dielectric measurements were carried out and the dielectric constant was calculated and plotted at all frequencies.

A Comparative Study of Very High Burning Rate Materials - HIVELITE compositions 300511 and 300435

DTIC Science & Technology

1982-08-01

explosives and more or as sensitive as RDX and HMX . Thermal Sensitivity Differential Thermal Analysis/Thermogravimetric Analysis (DTA/TGA) Simultaneous...impact than Comp B end RDX but is less sensitive than lead azide. HIVELITE 30051i on the other hand, is less sensitive than Comp B and RDX on the ERL...represents the alpha to beta phase transition of KNO 3 . This endotherm is followed by four exotherms with peaks at 538 K (265*C), 567 K (2940C), 598 K

A Novel DNA Binding Mechanism for maf Basic Region-Leucine Zipper Factors Inferred from a MafA-DNA Complex Structure and Binding Specificities

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

Lu, Xun; Guanga, Gerald P; Wan, Cheng

2012-11-13

MafA is a proto-oncoprotein and is critical for insulin gene expression in pancreatic β-cells. Maf proteins belong to the AP1 superfamily of basic region-leucine zipper (bZIP) transcription factors. Residues in the basic helix and an ancillary N-terminal domain, the Extended Homology Region (EHR), endow maf proteins with unique DNA binding properties: binding a 13 bp consensus site consisting of a core AP1 site (TGACTCA) flanked by TGC sequences and binding DNA stably as monomers. To further characterize maf DNA binding, we determined the structure of a MafA–DNA complex. MafA forms base-specific hydrogen bonds with the flanking G –5C –4 andmore » central C 0/G 0 bases, but not with the core-TGA bases. However, in vitro binding studies utilizing a pulse–chase electrophoretic mobility shift assay protocol revealed that mutating either the core-TGA or flanking-TGC bases dramatically increases the binding off rate. Comparing the known maf structures, we propose that DNA binding specificity results from positioning the basic helix through unique phosphate contacts. The EHR does not contact DNA directly but stabilizes DNA binding by contacting the basic helix. Collectively, these results suggest a novel multistep DNA binding process involving a conformational change from contacting the core-TGA to contacting the flanking-TGC bases.« less

Utility of dual source CT with ECG-triggered high-pitch spiral acquisition (Flash Spiral Cardio mode) to evaluate morphological features of ventricles in children with complex congenital heart defects.

PubMed

Nakagawa, Motoo; Ozawa, Yoshiyuki; Nomura, Norikazu; Inukai, Sachiko; Tsubokura, Satoshi; Sakurai, Keita; Shimohira, Masashi; Ogawa, Masaki; Shibamoto, Yuta

2016-04-01

We evaluated the ability of dual source CT (DSCT) with ECG-triggered high-pitch spiral acquisition (Flash Spiral Cardio mode) to depict the morphological features of ventricles in pediatric patients with congenital heart defects (CHD). Between July 2013 and April 2015, 78 pediatric patients with CHD (median age 4 months) were examined using DSCT with the Flash Spiral Cardio mode. The types of ventricular abnormalities were ventricular septal defect (VSD) in 42 (the malaligned type in 11, perimembranous type in 23, supracristal type in 2, atrioventricular type in 2, and muscular type in 4), single ventricle (SV) in 11, and congenital corrected transposition of the great arteries (ccTGA) in 4. We evaluated the accuracy of the diagnosis of the VSD type. In cases of SV and ccTGA, we assessed the detectability of the anatomical features of both ventricles for a diagnosis of ventricular situs. DSCT confirmed the diagnoses for all VSDs. The type of defect was precisely diagnosed for all patients. The anatomical features of both ventricles were also depicted and ventricular situs of SV and ccTGA was correctly diagnosed. The results suggest that DSCT has the ability to clearly depict the configuration of ventricles.

Gamma irradiation degradation/modification of 5-ethylidene 2-norbornene (ENB)-based ethylene propylene diene rubber (EPDM) depending on ENB content of EPDM and type/content of peroxides used in vulcanization

NASA Astrophysics Data System (ADS)

Özdemir, Tonguç

2008-06-01

In this study, the radiation degradation/modification of the vulcanized EPDM and the effects of dose rate, peroxide type/content in vulcanization system and ENB content of EPDM were studied to investigate the change in the extend of the modification/degradation of the mechanical properties of vulcanized EPDM via gamma irradiation. In addition, thermal, dynamic mechanical, ATR-FTIR, TGA, TGA-FTIR tests were carried out to understand the change of properties of vulcanized EPDM via irradiation. Samples were irradiated with two different dose rates of 1280 and 64.6 Gy/h. Total dose of irradiation was up to 184 kGy. The FTIR spectral analysis showed structural changes of EPDM via irradiation. It was observed that the dose rate changed the mechanical properties with different extends. The change of ENB content of EPDM and peroxide type and content in vulcanization system affect extend of the modification/degradation of the EPDM's properties.

Effects of gliadin addition on the rheological, microscopic and thermal characteristics of wheat gluten.

PubMed

Khatkar, B S; Barak, Sheweta; Mudgil, Deepak

2013-02-01

In the present study, micro-structural, thermal and rheological changes in the gluten network upon addition of gliadins at 5% and 10% levels were investigated using scanning electron microscopy (SEM), thermo gravimetric analysis (TGA), differential scanning calorimetry (DSC) and dynamic rheometry. The addition of gliadins decreased the peak dough height inferring decrease in dough strength. The dough stability also decreased from 3.20 to 1.40 min upon addition of 10% gliadin to the base flour. The TGA profile and the glass transition behavior of the control gluten and gluten obtained from dough with gliadin added at 5% and 10% levels showed decrease in thermal stability. The SEM micrograph of the control gluten showed foam like protein matrix. As the gliadin percentage in the gluten was increased, the compactness of the gluten structure reduced considerably leading to the formation of a more open weak gluten network. Copyright © 2012 Elsevier B.V. All rights reserved.

Conversion of glycerol to polyglycerol over waste duck-bones as a catalyst in solvent free etherification process

NASA Astrophysics Data System (ADS)

Ayoub, Muhammad; Sufian, Suriati; Mekuria Hailegiorgis, Sintayehu; Ullah, Sami; Uemura, Yoshimitsu

2017-08-01

The alkaline catalyst derived from the duck-bones was used for conversion of glycerol to polyglycerol via solvent free etherification process. The physicochemical properties of prepared materials were duck-bones were systematically investigated as a catalyst by latest techniques of Thermo gravimetric analysis (TGA), X-ray diffraction (XRD), and Brunauer-Emmett-Teller (BET) surface properties. TGA showed different trends of duck-bones decomposition from room temperature to 1000C. XRD pattern showed a clear and sharp peaks of a crystalline phase of CaO. The activity of the catalysts was in line with the basic amount of the strong base sites, surface area, and crystalline phase in the catalysts. The prepared catalyst derived from duck-bones provided high activity (99 %) for glycerol conversion and around 68 % yield for polyglycerol production. These ample wastes of duck-bones have good potential to be used as polyglycerol production catalysts due to have high quantity of Ca compare to other types of bones like cow, chicken and fish bones.

Thermal stability and haemolytic effects of depolymerized guar gum derivatives.

PubMed

Hussain, Majid; Zahoor, Tahir; Akhtar, Saeed; Ismail, Amir; Hameed, Aneela

2018-03-01

The purpose of current study was to purify and partially depolymerize guar gum by β-mannanase, HCl, Ba(OH) 2 actions and subjected to inspect compositional, thermogravimetric analysis (TGA) and haemolytic activity. Chemical composition revealed mannose and galactose ratio remained un-altered even after process of purification and hydrolysis. TGA thermograms affirmed initial and final decomposition temperature in various zones. Major decomposition stages apparently revealed partially hydrolyzed guar gum (PHGG) exhibited better heat stable properties having more zones of degradation than crude one. Furthermore, all guar fractions (2.5-250 mg/mL) were subjected to haemolysis to evaluate toxic effects during process of hydrolysis. The crude and hydrolyzed guar galactomannans exhibited minor haemolytic activity (1.9 ± 0.03-7.24 ± 0.02%) when compared to 0.1% Triton-X 100 (100% haemolysis) showing no toxic effects to human RBC's. Conclusively, hydrolyzed guar-galactomannans are safe and can be used in food products with improved heat stability.

Oxidation kinetics of hydride-bearing uranium metal corrosion products

NASA Astrophysics Data System (ADS)

Totemeier, Terry C.; Pahl, Robert G.; Frank, Steven M.

The oxidation behavior of hydride-bearing uranium metal corrosion products from Zero Power Physics Reactor (ZPPR) fuel plates was studied using thermo-gravimetric analysis (TGA) in environments of Ar-4%O 2, Ar-9%O 2, and Ar-20%O 2. Ignition of corrosion product samples from two moderately corroded plates was observed between 125°C and 150°C in all environments. The rate of oxidation above the ignition temperature was found to be dependent only on the net flow rate of oxygen in the reacting gas. Due to the higher net oxygen flow rate, burning rates increased with increasing oxygen concentration. Oxidation rates below the ignition temperature were much slower and decreased with increasing test time. The hydride contents of the TGA samples from the two moderately corroded plates, determined from the total weight gain achieved during burning, were 47-61 wt% and 29-39 wt%. Samples from a lightly corroded plate were not reactive; X-ray diffraction (XRD) confirmed that they contained little hydride.

Immobilized copper(II) macrocyclic complex on MWCNTs with antibacterial activity

NASA Astrophysics Data System (ADS)

Tarlani, Aliakbar; Narimani, Khashayar; Mohammadipanah, Fatemeh; Hamedi, Javad; Tahermansouri, Hasan; Amini, Mostafa M.

2015-06-01

In a new approach, a copper(II) tetraaza macrocyclic complex (CuTAM) was covalently bonded on modified multi-walled carbon nanotubes (MWCNTs). To achieve this purpose, MWCNTs were converted to MWCNT-COCl and then reacted to NH groups of TAM ligand. The prepared material was characterized by Fourier Transform Infrared (FT-IR), X-ray diffraction (XRD), Raman spectroscopy, thermal gravimetric analysis (TGA), and FESEM (field emission scanning electron microscopy). FT-IR and TGA demonstrated the presence of the organic moieties, and XRD proved that the structure of MWCNTs remained intact during the three modification steps. An increase in the ID/IG ratio in Raman spectra confirmed the surface modifications. Finally, the samples were subjected to an antibacterial assessment to compare their biological activity. The antibacterial test showed that the grafted complex on the surface of the nanotube (MWCNT-CO-CuTAM) has higher antibacterial activity against Bacillus subtilis ATCC 6633 than the MWCNT-COOH and CuTAM with 1000 and 2000 μg/mL.

A rapid and sensitive assay for determination of doxycycline using thioglycolic acid-capped cadmium telluride quantum dots

NASA Astrophysics Data System (ADS)

Tashkhourian, Javad; Absalan, Ghodratollah; Jafari, Marzieh; Zare, Saber

2016-01-01

A rapid, simple and inexpensive spectrofluorimetric sensor for determination of doxycycline based on its interaction with thioglycolic acid-capped cadmium telluride quantum dots (TGA/CdTe QDs) has been developed. Under the optimum experimental conditions, the sensor exhibited a fast response time of <10 s. The results revealed that doxycycline could quench the fluorescence of TGA/CdTe QDs via electron transfer from the QDs to doxycycline through a dynamic quenching mechanism. The sensor permitted determination of doxycycline in a concentration range of 1.9 × 10-6-6.1 × 10-5 mol L-1 with a detection limit of 1.1 × 10-7 mol L-1. The sensor was applied for determination of doxycycline in honey and human serum samples.

Study of crystallinity and thermal behavior of gamma irradiated luffa fiber

NASA Astrophysics Data System (ADS)

Patra, Subhashree; Mohanta, Kamal Lochan; Parida, Chhatrapati

2018-04-01

The purpose of this study is to examine the effect of high energy 6 MV X-ray photon beams on fiber of luffa cylindrica (LC), an agricultural waste of India. Techniques such as XRD, FTIR, SEM and TGA are used to study the structural changes and thermal behavior of fiber after physical modification by X-ray photon. Results illustrated that the crystallinity of cellulose in modified fibers was destroyed. High reactivity of modified LC fiber was ascertained from the presence of carboxylic group in the FT-IR spectrum. TGA study revealed increase in hydrophobicity of the modified fiber. The variation of these properties was analyzed with variation in dose of irradiation. Before treatment, the LC fibers are modified with Ca salts in order to explore their applications in biomedical terrain.

Synthesis, spectroscopic characterization, thermal studies, catalytic epoxidation and biological activity of chromium and molybdenum hexacarbonyl bound to a novel N 2O 2 Schiff base

NASA Astrophysics Data System (ADS)

Abdel Aziz, Ayman A.

2010-08-01

Complexes of M(CO) 6 (M = Cr and Mo) with novel Schiff base N,N'-bis(salicylidene)4,5-dichloro-1,2-phenylenediamine (H 2L) were prepared in benzene in two different conditions: (i) under reduced pressure resulting the dicarbonyl precursors [Cr(CO) 2(H 2L)] and [Mo(CO) 2(L)] and (ii) in air resulting the oxo complex [Cr(O)(L)] and the dioxo complex [Mo(O) 2(L)]. The complexes were characterized by elemental analysis, IR, 1H NMR, mass spectrometry, and magnetic measurement. Thermal behaviors of the complexes were also studied by using thermogravimetric analysis (TGA). The catalytic activity of the novel complexes in the epoxidation of cyclooctene, cyclohexene, 1-octene and 1-hexene with tert-butyl-hydroperoxide (TBHP) in methylene chloride was investigated. The antimicrobial activities of the ligand and their complexes have been screened against various strains of bacteria and fungi and the results have been compared with some known antibiotics.

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

Sun, Pei; Fang, Z. Zak; Koopman, Mark

Hydrogen has been investigated for decades as a temporary alloying element to refine the microstructure of Ti-6Al-4V, and is now being used in a novel powder metallurgy method known as "hydrogen sintering and phase transformation". Pseudo-binary phase diagrams of (Ti-6Al-4V)-xH have been studied and developed, but are not well established due to methodological limitations. In this paper, in situ studies of phase transformations during hydrogenation and dehydrogenation of (Ti-6Al-4V)-xH alloys were conducted using high-energy synchrotron X-ray diffraction (XRD), thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The eutectoid phase transformation of β ↔ α + δ was observed in themore » (Ti-6Al-4V)-xH alloy via in situ synchrotron XRD at 211 °C with a hydrogen concentration of 37.5 at.% (measured using TGA-DSC). The relationships of hydrogen composition to partial pressure and temperature were investigated in the temperature range 450-900°C. Based on these results, a partial pseudo-binary phase diagram of (Ti-6Al-4V)-xH is proposed for hydrogen compositions up to 60 at.% in the temperature range 100-900°C. Using the data collected in real time under controlled parameters of temperature, composition and hydrogen partial pressure, this work characterizes relevant phase transformations and microstructural evolution for practical titanium-hydrogen technologies of Ti-6Al-4V.« less

Facile synthesis of a novel magnesium amino-tris-(methylenephosphonate)-reduced graphene oxide hybrid and its high performance in mechanical strength, thermal stability, smoke suppression and flame retardancy in phenolic foam.

PubMed

Liu, Lei; Wang, Zhengzhou

2018-05-26

This study presents a one-step synthesis of a magnesium amino-tris-(methylenephosphonate) (Mg-AMP)-reduced graphene oxide (Mg-rGO) hybrid involving graphene oxide (GO) reduction and growth in situ of Mg-AMP nanoparticles in the absence of a reducing agent. Mg-rGO was characterized by X-ray diffraction, X-ray photoelectron and Fourier-transform infrared spectroscopies, transmission electronic microscopy, and thermogravimetric analysis (TGA). Mg-rGO was then used to prepare flame-retardant and toughened phenolic (PF) foam. This additive was found to enhance the compressive and flexural strengths of PF foam as well as to reduce its high friability and brittleness. The limiting oxygen index of the foam with 4 phr Mg-rGO (sample PF/4Mg-rGO) increased to 41.5%, compared with the 38% of untreated foam; the peak heat release rate and total heat release of sample PF/4Mg-rGO were decreased by 28.7 and 18.4%, respectively. Also, the total smoke release and peak CO production rate of PF/4Mg-rGO were reduced by 52.5 and 38.1%, respectively. TGA results indicated that Mg-rGO clearly improved the thermal stability of PF foam. Copyright © 2018 Elsevier B.V. All rights reserved.

Synthesis of nanoporous carbohydrate metal-organic framework and encapsulation of acetaldehyde

NASA Astrophysics Data System (ADS)

Al-Ghamdi, Saleh; Kathuria, Ajay; Abiad, Mohamad; Auras, Rafael

2016-10-01

Gamma cyclodextrin (γ-CD) metal organic frameworks (CDMOFs) were synthesized by coordinating γ-CDs with potassium hydroxide (KOH), referred hereafter as CDMOF-a, and potassium benzoate (C7H5KO2), denoted as CDMOF-b. The obtained CDMOF structures were characterized using nitrogen sorption isotherm, thermo-gravimetric analysis (TGA), X-ray diffraction (XRD), and scanning electron microscopy (SEM). High surface areas were achieved by the γ-CD based MOF structures where the Langmuir specific surface areas (SSA) of CDMOF-a and CDMOF-b were determined as 1376 m2 g-1 and 607 m2 g-1; respectively. The dehydrated CDMOF structures demonstrated good thermal stability up to 250 °C as observed by the TGA studies. XRD results for CDMOF-a and CDMOF-b reveal a body centered-cubic (BCC) and trigonal crystal system; respectively. Due to its accessible porous structure and high surface area, acetaldehyde was successfully encapsulated in CDMOF-b. During the release kinetic studies, we observed peak release of 53 μg of acetaldehyde per g of CDMOF-b, which was 100 times greater than previously reported encapsulation in β-CD. However, aldol condensation reaction occurred during encapsulation of acetaldehyde into CDMOF-a. This research work demonstrates the potential to encapsulate volatile organic compounds in CDMOF-b, and their associated release for applications including food, pharmaceuticals and packaging.

Process Development and Property Evaluation of Organosilicon Infiltrated Reaction Sintered Silicon Nitride (RSSN).

DTIC Science & Technology

1982-01-01

Battelle) (5) Prepolymer based on methyltrichlorosilane and ammonia (Battelle) (6) Polysilastyrene (Professor West, University of Wisconsin) (7...These types of materials are not commercially available, but are produced from commercial intermediates (methyldichlorosilane and ammonia ) and have been...methyltrichlorosilane and ammonia is a low melting, solid resin which has been shown to yield 72 percent residue by thermogravimetric analysis (TGA) in our work

Analysis of Two Methods for Characterization of Flame Resistant Military Fabrics and Commercial Textile Fibers: Simultaneous DSC-TGA and Pyrolysis GCMS

DTIC Science & Technology

2014-04-04

military clothing and shelters. Thus, higher demands are put on the industry to improve the flame-resistant (FR) properties of high performance...polymers under development for military clothing and individual equipment and fabric shelters: (1) simultaneous differential scanning calorimetry...ANSI Std. Z39.18 GC/MS POLYMERS POLYMER FIBERS PROTECTIVE CLOTHING FIBERS

Hydrogenation of liquid natural rubber via diimide reduction in hydrazine hydrate/hydrogen peroxide system

NASA Astrophysics Data System (ADS)

Yusof, Muhammad Jefri Mohd; Jamaluddin, Naharullah; Abdullah, Ibrahim; Yusoff, Siti Fairus M.

2015-09-01

Liquid natural rubber (LNR) with molecular weight of lower than 105 and shorter polymeric chain than natural rubber was prepared. LNR was then hydrogenated via diimide reduction by oxidation of hydrazine hydrate with hydrogen peroxide. The unsaturated units of the rubber were converted into saturated hydrocarbon to strengthen the backbone of the polymer so it was able to resist thermal degradation. The results indicated that hydrogenation degree of the product (HLNR) could be extended to 91.2% conversion under appropriate conditions. The hydrogenated LNR (HLNR) was characterized using Fourier-Transform Infrared (FTIR) and Nuclear Magnetic Resonance (NMR) spectroscopy. The physical characteristics of HLNR were analyzed with Termogravimetric Analysis (TGA).

Enhancement of Spartium junceum L. fibres properties

NASA Astrophysics Data System (ADS)

Kovačević, Z.; Bischof, S.; Antonović, A.

2017-10-01

Properties of lignocellulosic Spartium junceum L. (SJL) fibres were investigated in order to use them as reinforcement in composite material production. The fibres were obtained by microwave maceration process and additionally modified with NaOH, nanoclay and citric acid with the aim to improve their mechanical, thermal and other physical-chemical properties. Tensile and thermal properties of these natural fibres were enhanced by the different modification treatment which is investigated by the Vibrodyn/Vibroskop method and thermogravimetric analysis (TGA), whilst determination of chemical composition and fibre’s surface properties were explored using scanning electron microscope (SEM), electron dispersive spectroscopy (EDS) and elektrokinetic analyser. All the results show great improvement of nanoclay/citric acid modified SJL properties.

Preparation of poly(vinyl alcohol)/kaolinite nanocomposites via in situ polymerization

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

Jia Xin; Department of Chemistry, Hexi University, Zhangye 734000; Li Yanfeng

2008-03-04

Poly(vinyl alcohol)/kaolinite intercalated nanocomposites (Kao-PVA) were prepared via in situ intercalation radical polymerization. Vinyl acetate (VAc) was intercalated into kaolinite by a displacement method using dimethyl sulfoxide/kaolinite (Kao-DMSO) as the intermediate. Then, PVAc/kaolinite (Kao-PVAc) was obtained via radical polymerization with benzoyl peroxide (BPO) as initiator. Last, PVAc/kaolinite was saponified via direct-hydrolysis with NaOH solution in order to obtain PVA/kaolinite nanocomposites, which was characterized by Fourier-Transformation spectroscopy (FTIR), wide X-ray diffraction (WXRD) and transmission electron microscopy (TEM). Their differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) results of the obtained PVA/kaolinite suggested that the thermal properties had an obvious improvement.

A new Keggin-type polyoxometalate catalyst for degradation of aqueous organic contaminants

NASA Astrophysics Data System (ADS)

Olgun, Asim; Çolak, Alper Tolga; Gübbük, İ. Hilal; Şahin, Onur; Kanar, Ebru

2017-04-01

In this study, a new polyoxometalate, K16[Ni(H2O)6]2[BW12O40]4·48H2O (1) was synthesized at room temperature and characterized by X-ray single crystal diffractions, elemental analyses, IR spectra, and thermo gravimetric analyses (TGA). Crystal structure analysis reveals that compound 1 exhibits a supramolecular structure containing one Keggin-type [BW12O40]4 heteropoly anion. The catalytic properties of this molecule for the degradation of Methyl red (MR), Rhodamine B (RhB), Methyl orange (MO) and Congo red (CR) were investigated. The results show that the compound 1 is a promising catalyst candidate for dye degradation.

Echocardiography vs magnetic resonance imaging in assessing ventricular function and systemic atrioventricular valve status in adults with congenitally corrected transposition of the great arteries.

PubMed

Kowalik, Ewa; Mazurkiewicz, Łukasz; Kowalski, Mirosław; Klisiewicz, Anna; Marczak, Magdalena; Hoffman, Piotr

2016-11-01

The survival in adults with congenitally corrected transposition of the great arteries (ccTGA) might be reduced due to dysfunction of the systemic right ventricle (sRV). The quantitative echocardiographic assessment of sRV function and tricuspid (systemic atrioventricular valve) regurgitation (TR) is still a diagnostic challenge. Thus, the aim of this study was to compare echocardiographic indices of sRV function and the degree of TR with corresponding MRI (magnetic resonance imaging)-derived parameters in adults with ccTGA. A prospective cross-sectional study of adults with ccTGA referred to a tertiary congenital heart disease center was conducted. All patients underwent transthoracic echocardiography and MRI examinations. Thirty-three adults (19F/14M, mean age 34.1 years) were included. We found significantly lower fractional area change (FAC) and global longitudinal strain (GLS) values in patients with MRI-derived RV ejection fraction (EF) <45%. A cutoff GLS<-16.3% identified sRV EF ≥45% with a sensitivity of 77.3% and specificity of 72.7%. A very strong correlation between MRI- and echocardiography-derived TR volume was observed (r=.84; P<.0001). GLS is the variable with the best sensitivity but less specificity to distinguish between systemic RV EF ≥45% and below 45%, and it seems to be the preferred echocardiographic index of systemic RV function in adults with ccTGA. The quantitative assessment of TR by MRI and echocardiography showed a very strong agreement in patients with ccTGA. © 2016, Wiley Periodicals, Inc.

The effect of bioleaching on sewage sludge pyrolysis.

PubMed

Chen, Zhihua; Hu, Mian; Cui, Baihui; Liu, Shiming; Guo, Dabin; Xiao, Bo

2016-02-01

The effects of bioleaching on sewage sludge pyrolysis were studied. Sewage sludge was treated by bioleaching with solid concentrations of 6% (w/v), 8% (w/v), 10% (w/v). Results showed that bioleaching treatment could modify the physicochemical properties of sewage sludge and enhance the metals removal. The optimum removal efficiencies of heavy metals were achieved with solid concentration of 6% (w/v) bioleaching treatment: Cu, 73.08%; Zn, 78.67%; Pb, 24.65%; Cd, 79.46%. The characterization results of thermogravimetric analysis (TGA) showed that the bioleached sewage sludge with a 6% (w/v) solid concentration treatment was the easiest to decompose. Pyrolytic experiments of bioleached sewage sludge were performed in a laboratory-scale fixed bed reactor. Results indicated that bioleaching treatment greatly influenced the product yields and gas composition. Copyright © 2015 Elsevier Ltd. All rights reserved.

Differentiations of Chitin Content and Surface Morphologies of Chitins Extracted from Male and Female Grasshopper Species

PubMed Central

Kaya, Murat; Lelešius, Evaldas; Nagrockaitė, Radvilė; Sargin, Idris; Arslan, Gulsin; Mol, Abbas; Baran, Talat; Can, Esra; Bitim, Betul

2015-01-01

In this study, we used Fourier transform infrared spectroscopy (FT-IR), elemental analysis (EA), thermogravimetric analysis (TGA), X-ray diffractometry (XRD), and scanning electron microscopy (SEM) to investigate chitin structure isolated from both sexes of four grasshopper species. FT-IR, EA, XRD, and TGA showed that the chitin was in the alpha form. With respect to gender, two main differences were observed. First, we observed that the quantity of chitin was greater in males than in females and the dry weight of chitin between species ranged from 4.71% to 11.84%. Second, using SEM, we observed that the male chitin surface structure contained 25 – 90nm wide nanofibers and 90 – 250 nm nanopores, while no pores or nanofibers were observed in the chitin surface structure of the majority of females (nanofibers were observed only in M. desertus females). In contrast, the elemental analysis, thermal properties, and crystalline index values for chitin were similar in males and females. Also, we carried out enzymatic digestion of the isolated chitins using commercial chitinase from Streptomyces griseus. We observed that there were no big differences in digestion rate of the chitins from both sexes and commercial chitin. The digestion rates were for grasshoppers’ chitins; 88.45–95.48% and for commercial chitin; 94.95%. PMID:25635814

Can We Remember Future Actions yet Forget the Last Two Minutes? Study in Transient Global Amnesia

ERIC Educational Resources Information Center

Hainselin, Mathieu; Quinette, Peggy; Desgranges, Beatrice; Martinaud, Olivier; Hannequin, Didier; de La Sayette, Vincent; Viader, Fausto; Eustache, Francis

2011-01-01

Transient global amnesia (TGA) is a clinical syndrome characterized by the abrupt onset of a massive episodic memory deficit that spares other cognitive functions. If the anterograde dimension is known to be impaired in TGA, researchers have yet to investigate prospective memory (PM)--which involves remembering to perform an intended action at…

Left Ventricular Function after Arterial Switch Operation as Assessed by Two-Dimensional Speckle-Tracking Echocardiography in Patients with Simple Transposition of the Great Arteries

PubMed Central

Malakan Rad, Elaheh; Ghandi, Yazdan; Kocharian, Armen; Mirzaaghayan, Mohammadreza

2016-01-01

Background: The late postoperative course for children with transposition of the great arteries (TGA) with an intact ventricular septum (IVS) is very important because the coronary arteries may be at risk of damage during arterial switch operation (ASO). We sought to investigate left ventricular function in patients with TGA/IVS by echocardiography. Methods: From March 2011 to December 2012, totally 20 infants (12 males and 8 females) with TGA/IVS were evaluated via 2-dimensional speckle-tracking echocardiography (2D STE) more than 6 months after they underwent ASO. A control group of age-matched infants and children was also studied. Left ventricular longitudinal strain (S), strain rate (SR), time to peak systolic longitudinal strain (TPS), and time to peak systolic longitudinal strain rate (TPSR) were measured and compared between the 2 groups. Results: Mean ± SD of age at the time of study in the patients with TGA/IVS was 15 ± 5 months, and also age at the time of ASO was 12 ± 3 days. Weight was 3.13 ± 0.07 kg at birth and 8.83 ± 1.57 kg at the time of ASO. Global strain (S), Time to peak strain rate (TPSR), and Time to peak strain (TPS) were not significantly different between the 2 groups, whereas global strain rate (SR) was significantly different (p value < 0.001). In the 3-chamber view, the values of S in the lateral, septal, inferior, and anteroseptal walls were significantly different between the 2 groups (p value < 0.001), and SR in the posterior wall was significantly different between the 2 groups (p value < 0.001). There were no positive correlations between S and SR in terms of the variables of heart rate, total cardiopulmonary bypass time, and aortic cross-clamp time. There were no statistically significant differences between the 2 groups regarding S, SR, TPS, and TPSR in the anteroseptal and posterior walls in the 3-chamber view and in the lateral and septal walls in the 4-chamber view. Conclusion: We showed that between 6 and 18 months after a successful ASO, the parameters of S, SR, and global TPS were normal in our patients with TGA/IVS. However, LV myocardial TPSR did not normalize in this time period. PMID:27956909

Left Ventricular Function after Arterial Switch Operation as Assessed by Two-Dimensional Speckle-Tracking Echocardiography in Patients with Simple Transposition of the Great Arteries.

PubMed

Malakan Rad, Elaheh; Ghandi, Yazdan; Kocharian, Armen; Mirzaaghayan, Mohammadreza

2016-07-06

Background: The late postoperative course for children with transposition of the great arteries (TGA) with an intact ventricular septum (IVS) is very important because the coronary arteries may be at risk of damage during arterial switch operation (ASO). We sought to investigate left ventricular function in patients with TGA/IVS by echocardiography. Methods: From March 2011 to December 2012, totally 20 infants (12 males and 8 females) with TGA/IVS were evaluated via 2-dimensional speckle-tracking echocardiography (2D STE) more than 6 months after they underwent ASO. A control group of age-matched infants and children was also studied. Left ventricular longitudinal strain (S), strain rate (SR), time to peak systolic longitudinal strain (TPS), and time to peak systolic longitudinal strain rate (TPSR) were measured and compared between the 2 groups. Results: Mean ± SD of age at the time of study in the patients with TGA/IVS was 15 ± 5 months, and also age at the time of ASO was 12 ± 3 days. Weight was 3.13 ± 0.07 kg at birth and 8.83 ± 1.57 kg at the time of ASO. Global strain (S), Time to peak strain rate (TPSR), and Time to peak strain (TPS) were not significantly different between the 2 groups, whereas global strain rate (SR) was significantly different (p value < 0.001). In the 3-chamber view, the values of S in the lateral, septal, inferior, and anteroseptal walls were significantly different between the 2 groups (p value < 0.001), and SR in the posterior wall was significantly different between the 2 groups (p value < 0.001). There were no positive correlations between S and SR in terms of the variables of heart rate, total cardiopulmonary bypass time, and aortic cross-clamp time. There were no statistically significant differences between the 2 groups regarding S, SR, TPS, and TPSR in the anteroseptal and posterior walls in the 3-chamber view and in the lateral and septal walls in the 4-chamber view. Conclusion: We showed that between 6 and 18 months after a successful ASO, the parameters of S, SR, and global TPS were normal in our patients with TGA/IVS. However, LV myocardial TPSR did not normalize in this time period.

Application of lag-k autocorrelation coefficient and the TGA signals approach to detecting and quantifying adulterations of extra virgin olive oil with inferior edible oils.

PubMed

Torrecilla, José S; García, Julián; García, Silvia; Rodríguez, Francisco

2011-03-04

The combination of lag-k autocorrelation coefficients (LCCs) and thermogravimetric analyzer (TGA) equipment is defined here as a tool to detect and quantify adulterations of extra virgin olive oil (EVOO) with refined olive (ROO), refined olive pomace (ROPO), sunflower (SO) or corn (CO) oils, when the adulterating agents concentration are less than 14%. The LCC is calculated from TGA scans of adulterated EVOO samples. Then, the standardized skewness of this coefficient has been applied to classify pure and adulterated samples of EVOO. In addition, this chaotic parameter has also been used to quantify the concentration of adulterant agents, by using successful linear correlation of LCCs and ROO, ROPO, SO or CO in 462 EVOO adulterated samples. In the case of detection, more than 82% of adulterated samples have been correctly classified. In the case of quantification of adulterant concentration, by an external validation process, the LCC/TGA approach estimates the adulterant agents concentration with a mean correlation coefficient (estimated versus real adulterant agent concentration) greater than 0.90 and a mean square error less than 4.9%. Copyright © 2011 Elsevier B.V. All rights reserved.

Synthesis and Characterization of Novel Fluorine-Containing Water-Based Antirust Coating

NASA Astrophysics Data System (ADS)

Wang, Huiru; Wang, Xin; Zhao, Xiongyan

2018-01-01

A fluorine-containing polyacrylate copolymer emulsion was synthesized by a seed emulsion polymerization method, in which styrene(St) and butyl acrylate (BA) were used as main monomers and dodecafluoroheptyl methacrylate(DFMA) as fluorine-containing monomer. The structure and properties were characterized by Fourier transform infrared spectrum (FT-IR), scanning electron microscopy (SEM), particle size analysis, differential scanning calorimetry (DSC). The FTIR results showed that DFMA was effectively involved in the emulsion copolymerization, and the formed emulsion particles had a narrow particle size distribution. From the results salt spray test presented, it seems when the content of DFMA was 5wt% anti-rust performance of emulsion is relatively better. DSC and TGA also showed that their film exhibited higher thermal stability than that of fluorine-free emulsion.

Intercalation of biomolecules into NiAl-NO 3 layered double hydroxide films synthesized in situ on anodic alumina/aluminium support

NASA Astrophysics Data System (ADS)

Zhao, Hua-Zhang; Chang, Ying-Yue; Yang, Jing; Yang, Qin-Zheng

2013-03-01

Layered double hydroxide (LDH) films were synthesized in situ on anodic alumina/aluminium (AAO/Al). Glucose oxidase (GOD) and L-ascorbic acid (vitamin C, VC) were intercalated respectively into the in-situ grown LDH films by anion-exchange in aqueous solutions. Dodecylsulfate (SDS) was used to expand the lamellar structure before GOD intercalation into the LDH film. The resulting products were characterized by scanning electron microscopy (SEM), x-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy and thermo gravimetric analysis (TGA). The results showed that VC and GOD were successfully intercalated into the in-situ synthesized LDH film. These biomolecules loaded LDH films could have potential applications in electrode modification, safe storage and effective delivery of bioactive compounds.

Extraction of silica content from the Cymbopogan citratus (lemon grass) and its performance as reinforcement for polymers

NASA Astrophysics Data System (ADS)

Firdaus, M. Y. Nur; Osman, H.; Metselaar, H. S. C.; Rozyanty, A. R.

2017-07-01

Silica is widely used as sources for adsorption materials, medical additives and fillers in composite and rubber industries. The manufacturing process of commercial silica use in various industries is very expensive and energy extensive. Therefore, agricultural waste material such as lemon grass is seen as a potential alternative silica sources for replacement of commercial silica which is currently available in the industry. In this research, a simple method based on the acid leaching treatment with hydrochloric acid (HCl) was developed to produce purified silica from lemon grass, followed by thermal combustion at 600°C. Acid leaching temperatures of 33, 50, 80 and 110°C were used. The silica content, shape and texture of the lemon grass ash was characterized using scanning electron microcopy -energy-dispersive X-ray (SEM-EDX) analysis. The SEM analysis indicated the presence of tubular-shaped porous aggregates, spherical and fibrous shapes of untreated and treated lemon grass at 33°C to 110 °C. The highest silica content recorded was 73.46% for lemon grass treated at the highest leaching temperature of 110°C. The thermal stability of lemon grass ash was examined by using a thermogravimetric analysis (TGA) instrument. The TGA analysis shows that the untreated and treated lemon grass ash start to decompose at lower temperature (90 to 100°C). Lemon grass treated at the highest leaching temperature 110°C exhibit the highest thermal stability.

A comprehensive physicochemical, thermal, and spectroscopic characterization of zinc (II) chloride using X-ray diffraction, particle size distribution, differential scanning calorimetry, thermogravimetric analysis/differential thermogravimetric analysis, ultraviolet-visible, and Fourier transform-infrared spectroscopy

PubMed Central

Trivedi, Mahendra Kumar; Sethi, Kalyan Kumar; Panda, Parthasarathi; Jana, Snehasis

2017-01-01

Objective: Zinc chloride is an important inorganic compound used as a source of zinc and has other numerous industrial applications. Unfortunately, it lacks reliable and accurate physicochemical, thermal, and spectral characterization information altogether. Hence, the authors tried to explore in-depth characterization of zinc chloride using the modern analytical technique. Materials and Methods: The analysis of zinc chloride was performed using powder X-ray diffraction (PXRD), particle size distribution, differential scanning calorimetry (DSC), thermogravimetric analysis/differential thermogravimetric analysis (TGA/DTG), ultraviolet-visible spectroscopy (UV-vis), and Fourier transform-infrared (FT-IR) analytical techniques. Results: The PXRD patterns showed well-defined, narrow, sharp, and the significant peaks. The crystallite size was found in the range of 14.70–55.40 nm and showed average crystallite size of 41.34 nm. The average particle size was found to be of 1.123 (d10), 3.025 (d50), and 6.712 (d90) μm and average surface area of 2.71 m2/g. The span and relative span values were 5.849 μm and 1.93, respectively. The DSC thermogram showed a small endothermic inflation at 308.10°C with the latent heat (ΔH) of fusion 28.52 J/g. An exothermic reaction was observed at 449.32°C with the ΔH of decomposition 66.10 J/g. The TGA revealed two steps of the thermal degradation and lost 8.207 and 89.72% of weight in the first and second step of degradation, respectively. Similarly, the DTG analysis disclosed Tmax at 508.21°C. The UV-vis spectrum showed absorbance maxima at 197.60 nm (λmax), and FT-IR spectrum showed a peak at 511/cm might be due to the Zn–Cl stretching. Conclusions: These in-depth, comprehensive data would be very much useful in all stages of nutraceuticals/pharmaceuticals formulation research and development and other industrial applications. PMID:28405577

3D Printing of NinjaFlex Filament onto PEDOT:PSS-Coated Textile Fabrics for Electroluminescence Applications

NASA Astrophysics Data System (ADS)

Tadesse, Melkie Getnet; Dumitrescu, Delia; Loghin, Carmen; Chen, Yan; Wang, Lichuan; Nierstrasz, Vincent

2018-03-01

Electroluminescence (EL) is the property of a semiconductor material pertaining to emitting light in response to an electrical current or a strong electric field. The purpose of this paper is to develop a flexible and lightweight EL device. Thermogravimetric analysis (TGA) was conducted to observe the thermal degradation behavior of NinjaFlex. Poly(3,4-ethylenedioxythiophene):poly(styrene sulfonic acid)—PEDOT:PSS—with ethylene glycol (EG) was coated onto polyester fabric where NinjaFlex was placed onto the coated fabric using three-dimensional (3D) printing and phosphor paste, and BendLay filaments were subsequently coated via 3D printing. Adhesion strength and flexibility of the 3D-printed NinjaFlex on textile fabrics were investigated. The TGA results of the NinjaFlex depict no weight loss up to 150°C and that the NinjaFlex was highly conductive with a surface resistance value of 8.5 ohms/sq.; the coated fabric exhibited a uniform surface appearance as measured and observed by using four-probe measurements and scanning electron microscopy, respectively, at 60% PEDOT:PSS. The results of the adhesion test showed that peel strengths of 4160 N/m and 3840 N/m were recorded for polyester and cotton specimens, respectively. No weight loss was recorded following three washing cycles of NinjaFlex. The bending lengths were increased by only a factor of 0.082 and 0.577 for polyester and cotton samples at 0.1-mm thickness, respectively; this remains sufficiently flexible to be integrated into textiles. The prototype device emitted light with a 12-V alternating current power supply.

Cytotoxicity and metal ions removal using antibacterial biodegradable hydrogels based on N-quaternized chitosan/poly(acrylic acid).

PubMed

Mohamed, Riham R; Elella, Mahmoud H Abu; Sabaa, Magdy W

2017-05-01

Physically crosslinked hydrogels resulted from interaction between N,N,N-trimethyl chitosan chloride (N-Quaternized Chitosan) (NQC) and poly(acrylic acid) (PAA) were synthesized in different weight ratios (3:1), (1:1) and (1:3) taking the following codes Q3P1, Q1P1 and Q1P3, respectively. Characterization of the mentioned hydrogels was done using several analysis tools including; FTIR, XRD, SEM, TGA, biodegradation in simulated body fluid (SBF) and cytotoxicity against HepG-2 liver cancer cells. FTIR results proved that the prepared hydrogels were formed via electrostatic and H-bonding interactions, while XRD patterns proved that the prepared hydrogels -irrespective to their ratios- were more crystalline than both matrices NQC and PAA. TGA results, on the other hand, revealed that Q1P3 hydrogel was the most thermally stable compared to the other two hydrogels (Q3P1 and Q1P1). Biodegradation tests in SBF proved that these hydrogels were more biodegradable than the native chitosan. Examination of the prepared hydrogels for their potency in heavy metal ions removal revealed that they adsorbed Fe (III) and Cd (II) ions more than chitosan, while they adsorbed Cr (III), Ni (II) and Cu (II) ions less than chitosan. Moreover, testing the prepared hydrogels as antibacterial agents towards several Gram positive and Gram negative bacteria revealed their higher antibacterial activity as compared with NQC when used alone. Evaluating the cytotoxic effect of these hydrogels on an in vitro human liver cancer cell model (HepG-2) showed their good cytotoxic activity towards HepG-2. Moreover, the inhibition rate increased with increasing the hydrogels concentration in the culture medium. Copyright © 2017 Elsevier B.V. All rights reserved.

Angiogenesis-related gene expression analysis in celiac disease.

PubMed

Castellanos-Rubio, Ainara; Caja, Sergio; Irastorza, Iñaki; Fernandez-Jimenez, Nora; Plaza-Izurieta, Leticia; Vitoria, Juan Carlos; Maki, Markku; Lindfors, Katri; Bilbao, Jose Ramon

2012-05-01

Celiac disease (CD) involves disturbance of the small-bowel mucosal vascular network, and transglutaminase autoantibodies (TGA) have been related to angiogenesis disturbance, a complex phenomenon probably also influenced by common genetic variants in angiogenesis-related genes. A set of genes with "angiogenesis" GO term identified in a previous expression microarray experiment (SCG2, STAB1, TGFA, ANG, ERBB2, GNA13, PML, CASP8, ECGF1, JAG1, HIF1A, TNFSF13 and TGM2) was selected for genetic and functional studies. SNPs that showed a trend for association with CD in the first GWAS were genotyped in 555 patients and 541 controls. Gene expression of all genes was quantified in 15 pairs of intestinal biopsies (diagnosis vs. GFD) and in three-dimensional HUVEC and T84 cell cultures incubated with TGA-positive and negative serum. A regulatory SNP in TNFSF13 (rs11552708) is associated with CD (p = 0.01, OR = 0.7). Expression changes in biopsies pointed to TGM2 and PML as up-regulated antiangiogenic genes and to GNA13, TGFA, ERBB2 and SCG2 as down-regulated proangiogenic factors in CD. TGA seem to enhance TGM2 expression in both cell models, but PML expression was induced only in T84 enterocytes while GNA13 and ERBB2 were repressed in HUVEC endothelial cells, with several genes showing discordant effects in each model, highlighting the complexity of gene interactions in the pathogenesis of CD. Finally, cell culture models are useful tools to help dissect complex responses observed in human explants.

Characteristics of Ampel bamboo as a biomass energy source potential in Bali

NASA Astrophysics Data System (ADS)

Sucipta, M.; Putra Negara, D. N. K.; Tirta Nindhia, T. G.; Surata, I. W.

2017-05-01

Currently, non-renewable fossil energy dominates utilization of the world energy need for many applications. Efforts has been developed to find alternative renewable energy sources, due to fossil energy availability is diminishing. And one of renewable energy source is from biomass. The aim of this research is to determine characteristics of the Ampel bamboo (Bambusa vulgaris) as an energy potential of biomass. The Ampel bamboo’s characteristics possessed are evaluated based on its chemical composition; moisture, volatile, ash, and fixed carbon through proximate analysis; and also carbon, hydrogen and nitrogen content through ultimate analysis. From the Thermo-gravimetric analysis (TGA) indicates that Ampel bamboo contains of about 18.10% hemicelluloses, 47.75% cellulose and 18.86% lignin. While from the ultimate analysis results in the content of carbon, hydrogen, and Nitrogen of Ampel bamboo are 39.75%, 5.75% and 0% respectively. With such characteristics, it indicates that Ampel bamboo has an attractive potential as a renewable energy source.

Extraction and Physicochemical Characterization of a New Polysaccharide Obtained from the Fresh Fruits of Abelmoschus Esculentus

PubMed Central

Emeje, Martins; Isimi, Christiana; Byrn, Stephen; Fortunak, Joseph; Kunle, Olobayo; Ofoefule, Sabinus

2011-01-01

This paper is the first multi-scale characterization of the fluidize-dried gum extracted from the fresh fruits of the plant Abelmoschus esculentus. It describes the physical, thermal, sorptional and functional properties of this natural gum. Elemental analysis, scanning electron microscopy (SEM), particle size analysis, X-ray powder diffraction (XPRD), thermo-gravimetric analysis (TGA), differential scanning calorimetry (DSC), fourier transmittance infra red (FT-IR), and nuclear magnetic resonance (NMR) spectroscopy were used to characterize the gum sample. Abelmoschus Esculentus Gum (AEG) had a glass transition temperature (Tg) of 70°C and no melting peak. It showed a 14.91% loss in weight at 195°C. X-ray diffractogram showed numerous broad halos for AEG. Elemental analysis showed that AEG contains 39.5, 7.3, 51.8, and 1.4% carbon, hydrogen, oxygen and nitrogen respectively. The results obtained in this study established the fundamental characteristics of AEG and suggests its potential application in the food, cosmetic and pharmaceutical sectors. PMID:24250349

Photocatalytic properties of hierarchical ZnO flowers synthesized by a sucrose-assisted hydrothermal method

NASA Astrophysics Data System (ADS)

Lv, Wei; Wei, Bo; Xu, Lingling; Zhao, Yan; Gao, Hong; Liu, Jia

2012-10-01

In this work, hierarchical ZnO flowers were synthesized via a sucrose-assisted urea hydrothermal method. The thermogravimetric analysis/differential thermal analysis (TGA-DTA) and Fourier transform infrared spectra (FTIR) showed that sucrose acted as a complexing agent in the synthesis process and assisted combustion during annealing. Photocatalytic activity was evaluated using the degradation of organic dye methyl orange. The sucrose added ZnO flowers showed improved activity, which was mainly attributed to the better crystallinity as confirmed by X-ray photoelectron spectroscopy (XPS) analysis. The effect of sucrose amount on photocatalytic activity was also studied.

Co-axial Electrospun Polyacrylonitrile-Poly(methylmethacrylate) Nanofibers: Atomic Force Microscopy and Compositional Characterization

PubMed Central

Zander, N.E.; Strawhecker, K.E.; Orlicki, J.A.; Rawlett, A.M.; Beebe, T.P.

2011-01-01

Poly(methylmethacrylate) (PMMA)- Polyacrylonitrile (PAN) fibers were prepared using a conventional single-nozzle electrospinning technique. The as-spun fibers exhibited core-shell morphology as verified by transmission electron microscopy (TEM) and atomic force microscopy (AFM). AFM-phase and modulus mapping images of the fiber cross-section and x-ray photoelectron spectroscopy (XPS) analysis indicated PAN formed the shell and PMMA the core material. XPS, thermal gravimetric analysis (TGA), and elemental analysis were used to determine fiber compositional information. Soaking the fibers in solvent demonstrated removal of the core material, generating hollow PAN fibers. PMID:21928836

Examination of the regulatory frameworks applicable to biologic drugs (including stem cells and their progeny) in Europe, the U.S., and Australia: part I--a method of manual documentary analysis.

PubMed

Ilic, Nina; Savic, Snezana; Siegel, Evan; Atkinson, Kerry; Tasic, Ljiljana

2012-12-01

Recent development of a wide range of regulatory standards applicable to production and use of tissues, cells, and other biologics (or biologicals), as advanced therapies, indicates considerable interest in the regulation of these products. The objective of this study was to analyze and compare high-tier documents within the Australian, European, and U.S. biologic drug regulatory environments using qualitative methodology. Cohort 1 of the selected 18 high-tier regulatory documents from the European Medicines Agency (EMA), the U.S. Food and Drug Administration (FDA), and the Therapeutic Goods Administration (TGA) regulatory frameworks were subject to a manual documentary analysis. These documents were consistent with the legal requirements for manufacturing and use of biologic drugs in humans and fall into six different categories. Manual analysis included a terminology search. The occurrence, frequency, and interchangeable use of different terms and phrases were recorded in the manual documentary analysis. Despite obvious differences, manual documentary analysis revealed certain consistency in use of terminology across analyzed frameworks. Phrase search frequencies have shown less uniformity than the search of terms. Overall, the EMA framework's documents referred to "medicinal products" and "marketing authorization(s)," the FDA documents discussed "drug(s)" or "biologic(s)," and the TGA documents referred to "biological(s)." Although high-tier documents often use different terminology they share concepts and themes. Documents originating from the same source have more conjunction in their terminology although they belong to different frameworks (i.e., Good Clinical Practice requirements based on the Declaration of Helsinki, 1964). Automated (software-based) documentary analysis should be obtained for the conceptual and relational analysis.

Examination of the Regulatory Frameworks Applicable to Biologic Drugs (Including Stem Cells and Their Progeny) in Europe, the U.S., and Australia: Part I—A Method of Manual Documentary Analysis

PubMed Central

Savic, Snezana; Siegel, Evan; Atkinson, Kerry; Tasic, Ljiljana

2012-01-01

Recent development of a wide range of regulatory standards applicable to production and use of tissues, cells, and other biologics (or biologicals), as advanced therapies, indicates considerable interest in the regulation of these products. The objective of this study was to analyze and compare high-tier documents within the Australian, European, and U.S. biologic drug regulatory environments using qualitative methodology. Cohort 1 of the selected 18 high-tier regulatory documents from the European Medicines Agency (EMA), the U.S. Food and Drug Administration (FDA), and the Therapeutic Goods Administration (TGA) regulatory frameworks were subject to a manual documentary analysis. These documents were consistent with the legal requirements for manufacturing and use of biologic drugs in humans and fall into six different categories. Manual analysis included a terminology search. The occurrence, frequency, and interchangeable use of different terms and phrases were recorded in the manual documentary analysis. Despite obvious differences, manual documentary analysis revealed certain consistency in use of terminology across analyzed frameworks. Phrase search frequencies have shown less uniformity than the search of terms. Overall, the EMA framework's documents referred to “medicinal products” and “marketing authorization(s),” the FDA documents discussed “drug(s)” or “biologic(s),” and the TGA documents referred to “biological(s).” Although high-tier documents often use different terminology they share concepts and themes. Documents originating from the same source have more conjunction in their terminology although they belong to different frameworks (i.e., Good Clinical Practice requirements based on the Declaration of Helsinki, 1964). Automated (software-based) documentary analysis should be obtained for the conceptual and relational analysis. PMID:23283551

Development of processing diagrams for polymeric die attach adhesives

NASA Astrophysics Data System (ADS)

Hsiung, Jen-Chou

With a processing diagram, one can reduce the effort required to customize curing process conditions for polymeric die attach adhesives. Polymeric die attach adhesives are often cured per the manufacturer's recommendations during initial screening evaluations. In most cases, the recommended cure schedules have to be modified so as to fit differences in process equipment. Unfortunately, the modified cure schedule is usually determined by a trial-and-error method. An aim of our experiments is to understand the curing process of a wide range of polymeric die attach adhesives (conventional, fast, and snap cure adhesives) and to construct a processing diagram, i.e., "Bondability Diagram", so as to define the processing window. Such diagrams should be helpful in determining both the time and cure temperature required to produce high quality bonds. The bondability diagram can be constructed based on fundamental understandings of the phenomena involved in the curing process using a wide variety of tools. Differential Scanning Calorimetry (DSC) is utilized to study the cure kinetics and the extent of reaction. Dynamic Mechanical Analysis (DMA) is used to determine gelation times and melt viscosity under a shear mode. A modified Rheovibron is employed to perform cure characterizations under a tensile mode so that cure stresses could be determined. Thermogravimetric Analysis (TGA) is used to evaluate the outgassing phenomena. Optical Microscopy (OM) is used to detect voids. Results indicate that the cure behaviors of conventional, fast, and snap cure adhesives are different in several respects. The combination of DSC, DMA, TGA, OM, and lap shear test leads to a frame work of developing the bondability diagram concept. The bondability diagram concept provides a foundation for an understanding of the recommended cure schedule and allows one to design their own cure schedule.

2D-1D structural phase transformation of Co(II) 3,5-pyridinedicarboxylate frameworks with chromotropism.

PubMed

Cheansirisomboon, Achareeya; Pakawatchai, Chaveng; Youngme, Sujittra

2012-09-21

Two new metal-organic frameworks [Co(pydc)(H(2)O)(2)](n) (1) and [Co(pydc)(H(2)O)(4)](n)(H(2)O)(n) (2), (pydc = 3,5-pyridinedicarboxylate) have been synthesized by a diffusion method and characterized by single-crystal X-ray diffraction. The structure of 1 reveals an infinite 2D layer with honeycomb-like cavities in which each pydc ligand bridges three Co(II) ions. The adjacent 2D layers are orderly packed in an ABAB-type array via intermolecular interactions of the combined π-π stacking and hydrogen bonds to form a 3D supramolecular architecture. Interestingly, compound 1 exhibits a water induced crystal-to-amorphous transformation with chromotropism confirmed by spectroscopic techniques, elemental analysis, TGA and XRPD. When this amorphous phase (1A) was exposed to water vapor, it was readily converted into the second crystalline phase 1B with a color change. Moreover, a reversible process between 1A and 1B was performed. In the case of compound 2, pydc acts as didentate bridging ligand connecting two Co(II) ions, leading to a 1D zig-zag chain. Guest water molecules fill the gaps in between chains and form hydrogen bonds with the host chains stabilizing the 3D network of 2. Additionally, compound 2 also exhibits a water induced crystal-to-amorphous transformation with chromotropism and the reversible process was also performed between the dehydrated (2A) and rehydrated (2') forms. Surprisingly, the IR and UV-vis spectra, elemental analysis, TGA curve and XRPD pattern of the rehydrated second phase 1B are found to be identical to that of 2 and 2', these results confirm that 2, 2' and 1B are the same compound.

Thermal degradation of paper industry wastes from a recovered paper mill using TGA. Characterization and gasification test.

PubMed

Arenales Rivera, Jorge; Pérez López, Virginia; Ramos Casado, Raquel; Sánchez Hervás, José-María

2016-01-01

In this survey, a refuse derived fuel (RDF) was produced from paper industry wastes through a mechanical treatment (MT). The two main wastes generated from a recovered paper mill were rejects and de-inking sludge, which were produced principally in the pulping and de-inking processes, respectively. This work presents raw wastes characterization, fuel preparation and gasification tests performed in a circulating fluidized bed (CFB) gasifier pilot plant. The characterization was carried out by proximate and ultimate analysis. Several blends of pre-conditioned rejects and de-inking sludge were densified by means of pelletizing, studying the energy consumption and its quality properties. Besides, thermal degradation of blends was studied under thermogravimetric analysis (TGA). The experimental runs were made from 30 to 900°C in nitrogen atmosphere at three heating ranges, β=5, 10 and 20°C/min. Two thermal stages were identified during the thermal degradation, which are linked to cellulose and plastic degradation. In addition, kinetics parameters were estimated by the application of non-isothermal methods: Kissinger-Akahira-Sunose (KAS), Flynn-Ozawa-Wall (FOW) and Coats and Redfern. The activation energy values were about 140-160 kJ/mol and 60-80 kJ/mol for plastic and cellulosic materials, respectively. Regarding waste valorisation, a blend composed of 95% of rejects and 5% of de-inking sludge was selected for gasification tests. The energy consumption during the preparation was recorded and a gasification tests were done to prove the usability of these pellets in a CFB gasifier. The main results were a net calorific value (NCV) of 5 MJ/Nm(3) and a total tar content of 11.44 g/Nm(3) at an equivalence ratio (ER) of 0.3. Copyright © 2015 Elsevier Ltd. All rights reserved.

Production of cromolyn sodium microparticles for aerosol delivery by supercritical assisted atomization.

PubMed

Reverchon, Ernesto; Adami, Renata; Caputo, Giuseppe

2007-12-21

The purpose of this study was to produce cromolyn sodium (CS) micrometric particles with controlled particle size (PS) and PS distribution (PSD) suitable for aerosol delivery, using a supercritical fluids-based process. CS was micronized using the supercritical assisted atomization (SAA) technique at different solute concentrations in water and different precipitation temperatures. Two techniques were used to measure PS and PSD of produced particles: scanning electron microscopy image analysis and laser scattering analysis. The 2 techniques were compared to provide a complete description of the powder obtained. High-performance liquid chromatography analysis was used to verify the absence of degradation of CS after micronization; differential scanning calorimetry, thermogravimetric analysis (TGA), and X-ray analysis were performed to study the effect of operative conditions on the crystalline structure and on the water content of SAA micronized particles. The CS particles obtained were spherical, with a volumetric percentage of particles with a diameter ranging between 1 and 5 microm of 50% to 66%. The precipitation temperature had no significant effect on PSD, but high drying temperatures led to product degradation. Increasing the concentration of CS in water solution produced an increase in PS of the micronized particles. TGA showed that the micronized CS had a different hydration state than the untreated CS did. The micronized product was stable after 12 months of storage, and no modifications in structure, morphology, or crystallinity were detected. In conclusion, SAA is an efficient technique for micronization of CS, and stable spherical amorphous particles suitable for aerosol delivery can be produced.

A rapid and sensitive assay for determination of doxycycline using thioglycolic acid-capped cadmium telluride quantum dots.

PubMed

Tashkhourian, Javad; Absalan, Ghodratollah; Jafari, Marzieh; Zare, Saber

2016-01-05

A rapid, simple and inexpensive spectrofluorimetric sensor for determination of doxycycline based on its interaction with thioglycolic acid-capped cadmium telluride quantum dots (TGA/CdTe QDs) has been developed. Under the optimum experimental conditions, the sensor exhibited a fast response time of <10s. The results revealed that doxycycline could quench the fluorescence of TGA/CdTe QDs via electron transfer from the QDs to doxycycline through a dynamic quenching mechanism. The sensor permitted determination of doxycycline in a concentration range of 1.9×10(-6)-6.1×10(-5)molL(-1) with a detection limit of 1.1×10(-7)molL(-1). The sensor was applied for determination of doxycycline in honey and human serum samples. Copyright © 2015 Elsevier B.V. All rights reserved.

Electrochemical synthesis of poly(pyrrole-co-o-anisidine)/chitosan composite films

NASA Astrophysics Data System (ADS)

Yalçınkaya, Süleyman; Çakmak, Didem

2017-05-01

In this study, poly(pyrrole-co-o-anisidine)/chitosan composite films were electrochemically synthesized in various monomers feed ratio (pyrrole: o-anisidine; 9:1, 7:3, 1:1, 3:7 and 1:9) of pyrrole and o-anisidine on the platinum electrode. Electrochemical synthesis of the composite films was carried out via cyclic voltammetry technique. They were characterized by FT-IR, cyclic voltammetry, SEM micrographs, digital images, TGA and DSC techniques. The SEM results indicated that the particle size of the composite decreased with increasing o-anisidine ratio and the films became more likely to be smooth morphology. The TGA results proved that the film of the composite with 1:1 ratio showed highest final degradation temperature and lowest weight loss (83%) compared to copolymer and 9:1 1:9 composite films. The 1:1 composite film had higher thermal stability than copolymer and the other composite films (9:1 1:9). Meanwhile, electrochemical studies exhibited that the 1/9 composite film had good electrochemical stability as well.

Characterization and thermogravimetric analysis of lanthanide hexafluoroacetylacetone chelates

DOE PAGES

Shahbazi, Shayan; Stratz, S. Adam; Auxier, John D.; ...

2016-08-30

This work reports the thermodynamic characterizations of organometallic species as a vehicle for the rapid separation of volatile nuclear fission products via gas chromatography due to differences in adsorption enthalpy. Because adsorption and sublimation thermodynamics are linearly correlated, there is considerable motivation to determine sublimation enthalpies. A method of isothermal thermogravimetric analysis, TGA-MS and melting point analysis are employed on thirteen lanthanide 1,1,1,5,5,5-hexafluoroacetylacetone complexes to determine sublimation enthalpies. An empirical correlation is used to estimate adsorption enthalpies of lanthanide complexes on a quartz column from the sublimation data. Additionally, four chelates are characterized by SC-XRD, elemental analysis, FTIR and NMR.

Opto-Electronically Efficient Conjugated Polymers by Stress-Induced Molecular Constraints

DTIC Science & Technology

2012-07-15

TEM, JEOL JEM-2010) and checked by weight losses obtained from the thermogravimetric scans (TGA, Perkin-Elmer).[49-55] Scheme 1. Grafting P3HT...further analysis of the conduction pathways, e.g., the linear resistance networks,[40] but even without it, the jump frequency is predicted to...Nanocomposites: CNT Surface grafting, p-p interactions, and Gold Nanoparticles adsorption effect, Mater Thesis, Department of Materials Science and Engineering

Cyanate Ester Resin Modified with Nano-particles for Inclusion in Continuous Fiber Reinforced Composites

DTIC Science & Technology

2011-02-25

custom built rotating oven, to prevent settling during cure. The filler content in the test specimen are verified by thermogravimetric analysis (TGA...using a Shimadzu SA-CP3 centrifugal particle size analyzer. The moisture absorption of the nanoparticles was studied using a Q50 thermogravimetric ...low viscosity bisphenol E cyanate ester resin (BECy) resin reinforced with macro scale carbon fibers and negative CTE nanoparticles . Polymer

Unraveling the Decomposition Process of Lead(II) Acetate: Anhydrous Polymorphs, Hydrates, and Byproducts and Room Temperature Phosphorescence.

PubMed

Martínez-Casado, Francisco J; Ramos-Riesco, Miguel; Rodríguez-Cheda, José A; Cucinotta, Fabio; Matesanz, Emilio; Miletto, Ivana; Gianotti, Enrica; Marchese, Leonardo; Matěj, Zdeněk

2016-09-06

Lead(II) acetate [Pb(Ac)2, where Ac = acetate group (CH3-COO(-))2] is a very common salt with many and varied uses throughout history. However, only lead(II) acetate trihydrate [Pb(Ac)2·3H2O] has been characterized to date. In this paper, two enantiotropic polymorphs of the anhydrous salt, a novel hydrate [lead(II) acetate hemihydrate: Pb(Ac)2·(1)/2H2O], and two decomposition products [corresponding to two different basic lead(II) acetates: Pb4O(Ac)6 and Pb2O(Ac)2] are reported, with their structures being solved for the first time. The compounds present a variety of molecular arrangements, being 2D or 1D coordination polymers. A thorough thermal analysis, by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA), was also carried out to study the behavior and thermal data of the salt and its decomposition process, in inert and oxygenated atmospheres, identifying the phases and byproducts that appear. The complex thermal behavior of lead(II) acetate is now solved, finding the existence of another hydrate, two anhydrous enantiotropic polymorphs, and some byproducts. Moreover, some of them are phosphorescent at room temperature. The compounds were studied by TGA, DSC, X-ray diffraction, and UV-vis spectroscopy.

Bacterial cellulose composites loaded with SiO2 nanoparticles: Dynamic-mechanical and thermal properties.

PubMed

Sheykhnazari, Somayeh; Tabarsa, Taghi; Ashori, Alireza; Ghanbari, Abbas

2016-12-01

The aim of this paper was to prepare composites of bacterial cellulose (BC) filled with silica (SiO 2 ) nanoparticles to evaluate the influence of the SiO 2 contents (3, 5 and 7wt%) on the thermo-mechanical properties of the composites. BC hydro-gel was immersed in an aqueous solution of silanol derived from tetraethoxysilane (TEOS), the silanol was then converted into SiO 2 in the BC matrix by pressing at 120°C and 2MPa. The BC/SiO 2 translucent sheets were examined by dynamic-mechanical analysis (DMA), thermo gravimetric analysis (TGA), and scanning electron microscopy (SEM). The temperature dependence of the storage modulus, loss modulus and tan delta was determined by DMA. In general, the results revealed that the increment of storage modulus and thermal stability increased concomitantly with the augmentation of SiO 2 content. Therefore, it could be concluded that the mechanical properties of the composites were improved by using high amounts of nano silica. This would be a high aspect ratio of BC capable of connecting the BC matrix and SiO 2 , thereby enhancing a large contact surface and resulting in excellent coherence. A decrease of the storage modulus was consistent with increasing temperature, resulting from softening of the composites. The storage modulus of the composites increased in the order: BC/S7>BC/S5>BC/S3, while the loss modulus and tan delta decreased. On the other hand, the thermal stabilities of all BC/SiO 2 composites were remarkably enhanced as compared to the pristine BC. TGA curves showed that the temperature of decomposition of the pure BC gradually shifted from about 260°C to about 370°C as silica content increased. SEM observations illustrated that the nano-scale SiO 2 was embedded between the voids and nano-fibrils of the BC matrix. Overall, the results indicated that the successful synthesis and superior properties of BC/SiO 2 advocate its effectiveness for various applications. Copyright © 2016 Elsevier B.V. All rights reserved.

Effect of polyethelene oxide on the thermal degradation of cellulose biofilm – Low cost material for soft tissue repair in dentistry

PubMed Central

Tyler, Rakim; Schiraldi, David; Roperto, Renato; Faddoul, Fady; Teich, Sorin

2017-01-01

Background Bio cellulose is a byproduct of sweet tea fermentation known as kombusha. During the biosynthesis by bacteria cellulose chains are polymerized by enzyme from activated glucose. The single chains are then extruded through the bacterial cell wall. Interestingly, a potential of the Kombucha’s byproduct bio cellulose (BC) as biomaterial had come into focus only in the past few decades. The unique physical and mechanical properties such as high purity, an ultrafine and highly crystalline network structure, a superior mechanical strength, flexibility, pronounced permeability to gases and liquids, and an excellent compatibility with living tissue that reinforced by biodegradability, biocompatibility, large swelling ratios. Material and Methods The bio-cellulose film specimens were provided by the R.P Dressel dental materials laboratory, Department of Comprehensive Care, School of Dental Medicine, Case Western Reserve University, Cleveland, US. The films were harvested, washed with water and dried at room temperature overnight. 1wt% of PEG-2000 and 10wt% of NaOH were added into ultrapure water to prepare PEG/NaOH solution. Then bio-cellulose film was added to the mixture and swell for 3 h at room temperature. All bio-cellulose film specimens were all used in the TA Instruments Q500 Thermogravmetric Analyzer to investigate weight percent lost and degradation. The TGA was under ambient air conditions at a heating rate of 10ºC/min. Results and Conclusions PEG control exhibited one transition with the peak at 380ºC. Cellulose and cellulose/ PEG films showed 3 major transitions. Interestingly, the cellulose/PEG film showed slightly elevated temperatures when compared to the corresponding transitions for cellulose control. The thermal gravimetric analysis (TGA) degradation curves were analyzed. Cellulose control film exhibited two zero order transitions, that indicate the independence of the rate of degradation from the amount on the initial substance. The activation energies for three transitions for cellulose and cellulose/PEG showed increasingly higher values for the transitions at higher temperatures. Key words:TGA, Bio-cellulose, PEG. PMID:28828153

Material Assessment of L97A1/L96A1 Grenades by Fourier Transform Infrared Spectroscopy and Thermogravimetric Analysis

DTIC Science & Technology

2010-12-01

infrared (FTIR) spectroscopy Differential scanning calorimetry ( DSC ) L97A1/L96A1 grenades Thermogravimetric analysis (TGA) 16. SECURITY CLASSIFICATION OF...Spectroscopy The FTIR scan (fig. 3) shows two baseline materials • The blue spectra represent the Nylon 6 sample • The black spectra represent Nylon 6...The black spectra represent a sample taken from the body of the older grenade body • The relative size and location of all the peaks are identical

Characterization of some selected vulcanized and raw silicon rubber materials

NASA Astrophysics Data System (ADS)

Sasikala, A.; Kala, A.

2017-06-01

Silicone Rubber is a high need of importance of Medical devices, Implants, Aviation and Aerospace wiring applications. Silicone rubbers are widely used in industry, and there are in multiple formulations. A raw and vulcanized silicone rubber Chemical and Physical structures of particles was confirmed and mechanical strength has been analyzed by FTIR spectroscopy. Thermal properties studied from Thermo Gravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC) analysis. Activation energy of the rubber materials were calculated using Broido method, Piloyon-Novikova relation and coats-Red fern methods.

Right ventricular function and N-terminal pro-brain natriuretic peptide levels in adult patients with simple dextro-transposition of the great arteries.

PubMed

Martínez-Quintana, Efrén; Marrero-Negrín, Natalia; Gopar-Gopar, Silvia; Rodríguez-González, Fayna

2017-06-01

Dextro-transposition of the great arteries (d-TGA) patients is at high risk of developing right ventricular dysfunction and tricuspid regurgitation in adulthood. Determining the relation between echocardiographic parameters, N-terminal pro-brain natriuretic peptide (NT-pro-BNP) levels and the New York Heart Association (NYHA) functional class may help determining the best time to operate them. Patients with simple d-TGA operated in infancy with an atrial switch procedure (Mustard or Senning operation) were followed up in our Adult Congenital Heart Disease Unit. Analytical, echocardiographic, and clinical parameters were determined to evaluate the correlation between right echocardiographic ventricular function, NT-pro-BNP levels, and NYHA functional class. Twenty-four patients with d-TGA were operated in infancy of whom 17 alive patients had simple d-TGA. Nine patients had NT-pro-BNP levels lower than 200 pg/mL and eight patients were above 200 pg/mL. Patients with lower hemoglobin concentration, higher right ventricular diameter or under diuretic treatment showed significant higher NT-pro-BNP levels (above 200 pg/dL). The Spearman test showed a positive correlation between basal right ventricular diameter and tricuspid regurgitation with pro NT BNP levels (correlation coefficient of .624; P=.017 and .490; P=.046, respectively) and a negative correlation with the right ventricle fractional area change (-.508, P=.045). No correlation was seen between NT-pro-BNP levels and the rest of echocardiographic parameters or the NYHA functional class. NT-pro-BNP levels showed a positive correlation with basal right ventricular diameter and tricuspid regurgitation but not with NYHA association functional class in d-TGA patients. © 2017, Wiley Periodicals, Inc.

Bio-mediated synthesis of TiO2 nanoparticles and its photocatalytic effect on aquatic biofilm.

PubMed

Dhandapani, Perumal; Maruthamuthu, Sundram; Rajagopal, Gopalakrishnan

2012-05-02

The nano-TiO(2) was synthesized biologically employing Bacillus subtilis (FJ460362). These nanoparticles were characterized by FTIR, TGA-DTA, UV-Visible spectroscopy, XRD and TEM. FTIR and TGA results confirm that the organic impurities were completely removed while calcinating the resultant products. Band gap value was estimated from the UV-Visible spectrum and anatase crystal phase was confirmed by XRD. TEM images reveal that these particles were agglomerated; mostly spherical in shape with an average particle size of 10-30nm. The synthesized nano-TiO(2) particles were coated on glass slides, biofilm were grown and subjected to irradiation of polychromatic light to understand photocatalytic activity in controlling the aquatic biofilm. The bacterial killing process was established by Epi-fluorescence microscopy. The results reveal that biogenic TiO(2) nanomaterial acts as good photocatalyst by the generation of H(2)O(2) in the vicinity of the TiO(2)-biofilm interfaces to suppress the growth of the aquatic biofilm. Copyright © 2012 Elsevier B.V. All rights reserved.

Physicochemical of pillared clays prepared by several metal oxides

NASA Astrophysics Data System (ADS)

Rinaldi, Nino; Kristiani, Anis

2017-03-01

Natural clays could be modified by the pillarization method, called as Pillared Clays (PILCs). PILCs have been known as porous materials that can be used for many applications, one of the fields is catalysis. PILCs as two dimensional materials are interesting because their structures and textural properties can be controlled by using a metal oxide as the pillar. Different metal oxide used as the pillar causes different properties results of pillared clays. Usually, natural smectite clays/bentonites are used as a raw material. Therefore, a series of bentonite pillared by metal oxides was prepared through pillarization method. Variation of metals pillared into bentonite are aluminium, chromium, zirconium, and ferro. The physicochemical properties of catalysts were characterized by using X-ray Diffraction (XRD), Thermo Gravimetric Analysis (TGA), Brunauer-Emmett-Teller (BET) and Barret-Joyner-Halenda (BJH) analysis, and Fourier transform infrared spectroscopy (FTIR) measurement. Noteworthy characterization results showed that different metals pillared into bentonite affected physical and chemical properties, i.e. basal spacing, surface area, pore size distribution, thermal stability and acidity.

Research of obtaining TiO2 by sol-gel method using titanium isopropoxide TIP and tetra-n-butyl orthotitanate TNB

NASA Astrophysics Data System (ADS)

Gómez de Salazar, J. M.; Nutescu Duduman, C.; Juárez Gonzalez, M.; Palamarciuc, I.; Barrena Pérez, M. I.; Carcea, I.

2016-08-01

Titanium dioxide crystallises in three polymorphs: anatase, rutile and brookite. Rutile is most stable form of the TiO2 polymorphs. In this paper we concentrate on obtaining rutile and anatase, both used in various applications. The chosen method is sol-gel, which is a reliable method used for obtaining titanium oxides. We prepared titanium dioxide with using titanium isopropoxide (TIP) with chemical construction (C12H28O4Ti) and tetra-n-butyl orthotitanate (TNB) with chemical construction (C16H36O4Ti). The experiments were carried out in order to compare the results of the samples with similar reaction conditions, but with different precursors, thus concluding which precursor gives best results. Using different analysis techniques as X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM) and Thermogravimetric Analysis (TGA) we characterised the samples morphologically and structurally.

Effects of X-ray irradiation on the Eu3+ → Eu2+ conversion in CaAl2O4 phosphors

NASA Astrophysics Data System (ADS)

Gomes, Manassés A.; Carvalho, Jéssica C.; Andrade, Adriano B.; Rezende, Marcos V.; Macedo, Zélia S.; Valerio, Mário E. G.

2018-01-01

This paper reports structural and luminescence properties of Eu-doped CaAl2O4 produced by an alternative sol-gel method using coconut water. Results of differential thermal analysis (DTA), thermogravimetric analysis (TGA), and X-ray diffraction (XRD) allowed us to identify the best synthesis conditions for sample preparation. Simultaneous measurements of X-ray absorption spectroscopy (XAS) and X-ray excited optical luminescence (XEOL) were also performed in the X-ray energy range of the Eu LIII edge. Results from photoluminescence (PL) showed only the characteristic Eu3+ emission. However, radioluminescence emission spectra from Eu-doped CaAl2O4 shows a process of conversion of Eu3+ to Eu2+, which is induced by X-ray irradiation and is dependent on the radiation dose energy. X-ray absorption near edge structure (XANES) measurements corroborate Eu reduction due to irradiation, showing that only the Eu3+ ion is present in stable form in the CaAl2O4.

FTIR spectroscopic, thermal and XRD characterization of hydroxyapatite from new natural sources

NASA Astrophysics Data System (ADS)

Shaltout, Abdallah A.; Allam, Moussa A.; Moharram, Mohamed A.

2011-12-01

The inorganic constituents of 5 different plants (leaves and stalks) were investigated by using Fourier transformer infrared spectroscopy (FTIR), X-ray diffraction (XRD) and thermal analysis including thermal gravimetric analysis (TGA), derivative thermogravimetry (DTG) and differential scanning calorimetry (DSC). These plants are Catha edulis (Khat), basil, mint, green tea and trifolium. The absorption bands of carbonate ions CO 32- was exhibited at 1446 cm -1, and the phosphate ions PO 43- was assigned at 1105 and 1035 cm -1. At high temperatures (600, 700 and 600 °C) further absorption bands of the phosphate ions PO 43- was assigned at the frequencies 572, 617, 962, 1043 and 1110 cm -1 and the vibrational absorption band of the carbonate ions CO 32- was assigned at 871, 1416 and 1461 cm -1. X-ray diffraction and thermal analysis confirm the obtained results of FITR. Results showed that the main inorganic constituents of C. edulis and basil leaves are hydroxyapatite whereas the hydroxyapatite content in the other plant samples is less than that in case of C. edulis and basil plant leaves.

Small deformation viscoelastic and thermal behaviours of pomegranate seed pips CMC gels.

PubMed

Savadkoohi, Sobhan; Farahnaky, Asgar

2015-07-01

The current investigation presents an exploration in phase behaviour of carboxymethyl cellulose (CMC) produced from pomegranate seed pips compared to low and high viscosity CMCs (LMCMC and HMCMC) primarily at low solid concentrations. Cellulose was extracted with 10 % NaOH at 35 °C for 22 h from pomegranate seed pips and converted to CMC by etherification process. Thermomechanical analysis and micro-imaging were carried out using small deformation dynamic oscillation in shear, modulated differential scanning calorimetry (MDSC) and scanning electron microscopy (SEM). The results emphasize the importance of molecular interaction and the degree of substitution in produced CMC. Thermal gravimetric analysis (TGA) thermograms showed an initial weight loss in pomegranate seed pips CMC (PSCMC) sample, which we attribute to presence of amount of moisture in sample powder. MDSC analysis of PSCMC showed five different peaks at 84, 104, 173, 307 and 361 °C. Moreover, G' and G" changes were found to be dependent on both concentration and frequency. The results of frequency sweep and tan δ indicate that PSCMC solutions can be classified as weak gels.

Thermogravimetric analysis of the behavior of sub-bituminous coal and cellulosic ethanol residue during co-combustion.

PubMed

Buratti, C; Barbanera, M; Bartocci, P; Fantozzi, F

2015-06-01

The influence of the addition of cellulosic ethanol residue (CER) on the combustion of Indonesian sub-bituminous coal was analyzed by non isothermal thermo-gravimetric analysis (TGA). The effect of blends ratio (5%, 10%, 15% and 20%), interaction mechanism, and heating rate (5°C/min, 10°C/min, 15°C/min, 20°C/min) on the combustion process was studied. The results show that the increase of the blending ratio allows to achieve the increase of the combustibility index from 7.49E-08 to 5.26E-07 at the blending ratio of 20%. Two types of non-isothermal kinetic analysis methods (Ozawa-Flynn-Wall and Vyazovkin) were also applied. Results indicate that the activation energy of the blends decreases with increasing the conversion rate. In particular, the blending ratio of 20% confirms to have the better combustion performance, with the average value of the activation energy equal to 41.10 kJ/mol obtained by Ozawa-Flynn-Wall model and 31.17 kJ/mol obtained by Vyazovkin model. Copyright © 2015 Elsevier Ltd. All rights reserved.

Formation of continuous activated carbon fibers for barrier fabrics

NASA Astrophysics Data System (ADS)

Liang, Ying

1997-08-01

Commercial protective suits made of active carbon granules or nonwoven fabrics are heavy, have low moisture vapor transport rate, and are uncomfortable. Inherent problems due to construction of barrier fabrics lead to severe heat stress when worn for even short time in warm environments. One proposed method to eliminate these problems is to facilitate the construction of a fabric made of continuous activated carbon fibers (CACF). This study is directed toward investigating the possibility of developing CAFC from two precursors: aramid and fibrillated PAN fiber. It was shown in this study that Kevlar-29 fibers could be quickly carbonized and activated to CACF with high adsorptivity and relatively low weight loss. CACF with high surface area (>500 msp2/g) and reasonable tenacity (≈1g/denier) were successfully prepared from Kevlar fibers through a three-step process: pretreatment, carbonization, and activation. X-ray diffraction, Fourier Transform Infrared Spectroscopy (FTIR), and thermal analysis were conducted to understand the evolution of physical and chemical properties during pretreatment. The influence of temperature, heating rate, and pyrolysis environment on the thermal behavior was determined by DSC and TGA/DTA and used as an indicator for optimizing the pyrolysis conditions. Surface analysis by nitrogen isotherms indicated that the resultant fibers had micropores and mesopores on the surface of CACF. This was also inferred by studies on the surface morphology through Scanning Electron Microscopy (SEM) and Scanning Tunneling Microscopy (STM). An investigation of the surface chemical structure by X-ray photoelectron spectroscopy (XPS) before and after activation and elemental analysis confirmed that adsorption of Kevlar based CACF mainly arises due to the physisorption instead of chemisorption. A multistep stabilization along with carbonization and activation was used to prepare active carbon fiber from fibrillated PAN fiber. The resultant fiber retained its fibrillar structure and provided a very high surface area, up to 1400 msp2/g, but was brittle. The characterization of the thermal behavior, mechanical properties, and surface structure of the pyrolyzed fiber at each processing step was also carried out by using various techniques, such as DSC and TGA, Instron, and SEM. These studies provide directions for preparation of CACF from novel precursors.

Anti-tissue transglutaminase antibodies and their role in the investigation of coeliac disease.

PubMed

Hill, P G; McMillan, S A

2006-03-01

Coeliac disease (CD), caused by an inappropriate T-cell-mediated immune response to the ingestion of cereal proteins in genetically susceptible individuals, is a common disorder with a prevalence of about 1% in Caucasian populations. It has a strong association with other autoimmune disorders, particularly type 1 diabetes and autoimmune thyroid disease. Although primarily affecting the small bowel, CD is a multisystem disorder and the adult or child patient may initially present to a wide range of clinical specialties. The concept of the 'coeliac iceberg' has been used to emphasize that many cases currently remain undiagnosed. The identification of tissue transglutaminase (TGA)-2 as the antigen against which the autoantibodies are directed has led to a greater understanding of the pathogenesis of CD and to the development of improved serological tests. Enzyme-linked immunoassays using human tissue TGA as antigen have high diagnostic sensitivity and specificity for the detection of CD. This review examines the evidence for adopting IgA anti-tissue TGA as the first-line diagnostic test for CD. It recommends a laboratory algorithm for the use and interpretation of TGA to enable the clinical laboratory to play a full part in detecting and monitoring a disorder that is eminently treatable once the diagnosis has been considered and confirmed.

A closer look at 40Ar/39Ar systematics of illite, recoil, retention ages, total gas ages, and a new correction method

NASA Astrophysics Data System (ADS)

Fitz-Diaz, E.; Hall, C. M.; van der Pluijm, B.

2013-12-01

One of the fundamentals of 40Ar-39Ar systematics of illite considers the effects of 39Ar recoil (ejection of 39Ar from tiny illite crystallites during the nuclear reaction 39K(n,p)39Ar), for which sample vacuum encapsulation prior to irradiation has been used since the 1990's. This technique separately measures the fraction of recoiled 39Ar and the Ar (39Ar and 40Ar) retained within illite crystals as they degas during step heating in vacuum. Total-gas ages (TGA) are calculated by using both recoiled and retained argon, while retention ages (RA) only involve retained Ar. Observations in numerous natural examples have shown that TGA fit stratigraphic constraints of geological processes when the average illite crystallite thickness (ICT) is smaller than 10nm, and that RA better matches these constrains for larger ICTs. Illite crystals with ICT >50nm show total gas and retention ages within a few My and they are identical, within analytical error, when ICT exceeds 150nm. We propose a new age correction that takes into account the average ICT and corresponding recoil for a sample , with such corrected ages (XCA) lying between the TGA and RA end-member ages. We apply this correction to samples containing one generation of illite and it particularly affects illite populations formed in the anchizone, with typical ICT values between 10-40nm. We analyzed bentonitic samples (S1, S2 and S3) from sites in Cretaceous carbonates in the front of the Monterrey salient in northern Mexico. Four size fractions (<0.05, 0.05-0.2, 0.2-1 & 1-2 μm) were separated, analyzed with XRD and dated by Ar-Ar. XRD analysis provides mineralogic characterization, illite polytype quantification, and illite crystallite thickness (ICT) determination using half-height peak width (illite crystallinity) and the Scherrer equation. All samples contain illite as the main mineral phase, ICT values between 8-27nm, from fine to coarser grain size fractions. Ages show a range in TGA among the different size fractions of S1, S2 and S3, respectively: 46-49, 36-43 and 40-52 My) and RA (54-64, 47-52 and 53-54 My. XCA calculations produce tighter constrained ranges (53-57, 45.5-48.5 and 49-52 My) with an overall average 51.1Ma×3.9 My. In the ICT vs. apparent age plot, authigenic illite grains show a greater slope that is in general slightly positive for TGA, slightly negative for RA, but close to zero for XCA. In the ICT vs. XCA plot thinner crystallites shows more dispersion than thicker ones. In order to test if such dispersion in the age of the finer/thinner illite is due to a different formation history in each site or the result of retention capability, degassing spectra were modeled for site XCA averages and overall XCA average. The modeling shows that local site ages best match the measured spectra, instead of a single age for the combined sites. The closeness between experimental and artificial degassing patterns also supports the hypothesis that each sample preserves a single age population. All illite grains in these samples grew progressively during folding in a time window that is constrained by the three sites. Small and large grains represent the same population in each sample, representing progressive degrees of grain growth (Ostwald ripening).

Immobilization Effect of Morphological, Thermal and Optical Properties in Biotemplate on Zinc Oxide Nanocomposite from Chitosan

NASA Astrophysics Data System (ADS)

Karpuraranjith, M.; Thambidurai, S.

Biotemplate-based zinc oxide nanocomposite was effectively prepared via simple chemical precipitation route. The functional groups of amino (-NH2), hydroxyl (-OH) and O-Zn-O were confirmed and characterized by FTIR spectroscopy. The structural and morphological properties were confirmed by XRD, UV-Vis DRS, HR-SEM and TEM analyses. The elemental composition of carbon, nitrogen, zinc and oxygen was confirmed by energy-dispersive X-ray analysis (EDAX) and Brunauer-Emmett-Teller high surface area of materials was estimated to be 52.49m2/g, respectively. Thermogravimetric analysis (TGA) shows that biotemplate on zinc oxide nanocomposite has higher thermal stability than chitosan matrix. The results demonstrate that biotemplate on zinc oxide matrix causes immobilization effect among the two components. Therefore, chitosan-ZnO nanocomposite has a microcrystalline morphological structure and also good thermal stability, so it can be a promising material for sensors, medical, tissue engineering and wastewater treatment applications.

Coordination Polymer: Synthesis, Spectral Characterization and Thermal Behaviour of Starch-Urea Based Biodegradable Polymer and Its Polymer Metal Complexes

PubMed Central

Malik, Ashraf; Parveen, Shadma; Ahamad, Tansir; Alshehri, Saad M.; Singh, Prabal Kumar; Nishat, Nahid

2010-01-01

A starch-urea-based biodegradable coordination polymer modified by transition metal Mn(II), Co(II), Ni(II), Cu(II), and Zn(II) was prepared by polycondensation of starch and urea. All the synthesized polymeric compounds were characterized by Fourier transform-infrared spectroscopy (FT-IR), 1H-NMR spectroscopy, 13C-NMR spectroscopy, UV-visible spectra, magnetic moment measurements, differential scanning calorimeter (DSC), and thermogravimetric analysis (TGA). The results of electronic spectra and magnetic moment measurements indicate that Mn(II), Co(II), and Ni(II) complexes show octahedral geometry, while Cu(II) and Zn(II) complexes show square planar and tetrahedral geometry, respectively. The thermogravimetric analysis revealed that all the polymeric metal complexes are more thermally stable than the parental ligand. In addition, biodegradable studies of all the polymeric compounds were also carried out through ASTM standards of biodegradable polymers by CO2 evolution method. PMID:20414461

Thermal Degradation and Combustion Behavior of Polypropylene/MWCNT Composites

NASA Astrophysics Data System (ADS)

Zaikov, G. E.; Rakhimkulov, A. D.; Lomakin, S. M.; Dubnikova, I. L.; Shchegolikhin, A. N.; Davidov, E. Ya.

2010-06-01

Studies of thermal and fire-resistant properties of the polypropylene/multi-walled carbon nanotube composites (PP/MWCNT) prepared by means of melt intercalation are discussed. The sets of the data acquired with the aid of non-isothermal TG experiments have been treated by the model kinetic analysis. The thermal-oxidative degradation behavior of PP/MWCNT and stabilizing effect caused by addition of MWCNT has been investigated by means of TGA and EPR spectroscopy. The results of cone calorimetric tests lead to the conclusion that char formation plays a key role in the mechanism of flame retardation for nanocomposites. This could be explained by the specific antioxidant properties and high thermal conductivity of MWCNT which determine high-performance carbonization during thermal degradation process. Comparative analysis of the flammability characteristics for PP-clay/MWCNT nanocomposites was provided in order to emphasize the specific behavior of the nanocomposites under high-temperature tests.

Adsorption of polyethylene glycol (PEG) onto cellulose nano-crystals to improve its dispersity.

PubMed

Cheng, Dong; Wen, Yangbing; Wang, Lijuan; An, Xingye; Zhu, Xuhai; Ni, Yonghao

2015-06-05

In this work, the adsorption of polyethylene glycol (PEG) onto cellulose nano-crystals (CNC) was investigated for preparing re-dispersible dried CNC. Results showed that the re-dispersity of CNC in water can be significantly enhanced using a PEG1000 dosage of 5wt% (based on the dry weight of CNC). The elemental analysis confirmed the adsorption of PEG onto the CNC surface. Transmission electron microscopy (TEM) was used to characterize the dry powder and indicated that the irreversible agglomeration of CNC after drying was essentially eliminated based on the PEG adsorption concept. Thermo-gravimetric analysis (TGA) and X-ray diffraction (XRD) suggested that CNC crystallinity and thermal stability were not affected by the adsorption of PEG. Thus, the adsorption of PEG has great potential for producing re-dispersible powder CNC. Copyright © 2015 Elsevier Ltd. All rights reserved.

Fractionation and physicochemical characterization of lignin from waste jute bags: Effect of process parameters on yield and thermal degradation.

PubMed

Ahuja, Dheeraj; Kaushik, Anupama; Chauhan, Ghanshyam S

2017-04-01

In this work lignin was extracted from waste jute bags using soda cooking method and effect of varying alkali concentration and pH on yield, purity, structure and thermal degradation of lignin were studied. The Lignin yield, chemical composition and purity were assessed using TAPPI method and UV-vis spectroscopy. Yield and purity of lignin ranged from 27 to 58% and 50-94%, respectively for all the samples and was maximum for 8% alkali concentration and at pH 2 giving higher thermal stability. Chemical structure, thermal stability and elementary analysis of lignin were studied using FTIR, H NMR, thermo gravimetric analysis (TGA) and Elemental analyzer. FTIR and H NMR results showed that core structure of lignin starts breaking beyond 10% alkali concentration. S/G ratio shows the dominance of Syringyl unit over guaiacyl unit. Copyright © 2017 Elsevier B.V. All rights reserved.

BiOBr microspheres for photocatalytic degradation of an anionic dye

NASA Astrophysics Data System (ADS)

Mera, Adriana C.; Váldes, Héctor; Jamett, Fabiola J.; Meléndrez, M. F.

2017-03-01

BiOBr microspheres were obtained using a solvothermal synthesis route in the presence of ethylene glycol and KBr at 145 °C, for 18 h. BiOBr microspheres were characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA), nitrogen adsorption-desorption isotherms analysis, diffuse reflectance spectroscopy (DRS), and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). Additionally, the theoretical and experimental isoelectric points (IEP) of BiOBr nanostructured microspheres were determined, and pH's influence on the degradation of an anionic dye (methyl orange) under simulated solar radiation was analyzed. Results show that 97% of methyl orange is removed at pH 2 after 60 min of photocatalytic reaction. Finally, DRIFTS studies permit the proposal of a surface reaction mechanism of the photocatalytic oxidation of MO using BiOBr microspheres.

Synthesis and structural characterization of CdS nanoparticles using nitrogen adducts of mixed diisopropylthiourea and dithiolate derivatives of Cd(II) complexes

NASA Astrophysics Data System (ADS)

Osuntokun, Jejenija; Ajibade, Peter A.

2015-07-01

[Cd(diptu)2(ced)], [Cd(diptu)2(ced)(bpy)], [Cd(diptu)2(ced)(phen)], (where diptu = diisopropyl thiourea; ced = 1-cyano-1-carboethoxylethylene-2,2‧-dithiolate; bpy = 2,2‧-bipyridine and phen = 1,10-phenanthroline) have been prepared and used as single source precursors for the preparation of hexadecylamine capped CdS nanoparticles. The precursor complexes were characterized by elemental analysis, FTIR and TGA. The structural properties of the nanoparticles were investigated using powder X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy techniques (SEM). The optical properties of the nanoparticles were studied using UV-Visible and photoluminescence spectroscopy. The XRD analysis showed that the nanoparticles were indexed to the hexagonal phase of CdS and the TEM results showed CdS nanoparticles with average crystallite sizes of 4.00-8.80 nm.

Preparation and characterization of a novel adsorbent from Moringa oleifera leaf

NASA Astrophysics Data System (ADS)

Bello, Olugbenga Solomon; Adegoke, Kayode Adesina; Akinyunni, Opeyemi Omowumi

2017-06-01

A new and novel adsorbent was obtained by impregnation of Moringa oleifera leaf in H2SO4 and NaOH, respectively. Prepared adsorbents were characterized using elemental analysis, FT-IR, SEM, TGA and EDX analyses, respectively. The effects of operational parameters, such as pH, moisture content, ash content, porosity and iodine number on these adsorbents were investigated and compared with those of commercial activated carbon (CAC). EDX results of acid activated M. oleifera leaf have the highest percentage of carbon by weight (69.40 %) and (76.11 %) by atom, respectively. Proximate analysis showed that the fixed carbon content of acid activated M. oleifera leaf (69.14 ± 0.01) was the highest of all adsorbents studied. Conclusively, the present investigation shows that acid activated M. oleifera leaf is a good alternative adsorbent that could be used in lieu of CAC for recovery of dyes and heavy metal from aqueous solutions and other separation techniques.

Unifying Principles of the Reductive Covalent Graphene Functionalization.

PubMed

Abellán, Gonzalo; Schirowski, Milan; Edelthalhammer, Konstantin F; Fickert, Michael; Werbach, Katharina; Peterlik, Herwig; Hauke, Frank; Hirsch, Andreas

2017-04-12

Covalently functionalized graphene derivatives were synthesized via benchmark reductive routes using graphite intercalation compounds (GICs), in particular KC 8 . We have compared the graphene arylation and alkylation of the GIC using 4-tert-butylphenyldiazonium and bis(4-(tert-butyl)phenyl)iodonium salts, as well as phenyl iodide, n-hexyl iodide, and n-dodecyl iodide, as electrophiles in model reactions. We have put a particular focus on the evaluation of the degree of addition and the bulk functionalization homogeneity (H bulk ). For this purpose, we have employed statistical Raman spectroscopy (SRS), and a forefront characterization tool using thermogravimetric analysis coupled with FT-IR, gas chromatography, and mass spectrometry (TGA/FT-IR/GC/MS). The present study unambiguously shows that the graphene functionalization using alkyl iodides leads to the best results, in terms of both the degree of addition and the H bulk . Moreover, we have identified the reversible character of the covalent addition chemistry, even at temperatures below 200 °C. The thermally induced addend cleavage proceeds homolytically, which allows for the detection of dimeric cleavage products by TGA/FT-IR/GC/MS. This dimerization points to a certain degree of regioselectivity, leading to a low sheet homogeneity (H sheet ). Finally, we developed this concept by performing the reductive alkylation reaction in monolayer CVD graphene films. This work provides important insights into the understanding of basic principles of reductive graphene functionalization and will serve as a guide in the design of new graphene functionalization concepts.

High temperature transformations of waste printed circuit boards from computer monitor and CPU: Characterisation of residues and kinetic studies.

PubMed

Rajagopal, Raghu Raman; Rajarao, Ravindra; Sahajwalla, Veena

2016-11-01

This paper investigates the high temperature transformation, specifically the kinetic behaviour of the waste printed circuit board (WPCB) derived from computer monitor (single-sided/SSWPCB) and computer processing boards - CPU (multi-layered/MLWPCB) using Thermo-Gravimetric Analyser (TGA) and Vertical Thermo-Gravimetric Analyser (VTGA) techniques under nitrogen atmosphere. Furthermore, the resulting WPCB residues were subjected to characterisation using X-ray Fluorescence spectrometry (XRF), Carbon Analyser, X-ray Photoelectron Spectrometer (XPS) and Scanning Electron Microscopy (SEM). In order to analyse the material degradation of WPCB, TGA from 40°C to 700°C at the rates of 10°C, 20°C and 30°C and VTGA at 700°C, 900°C and 1100°C were performed respectively. The data obtained was analysed on the basis of first order reaction kinetics. Through experiments it is observed that there exists a substantial difference between SSWPCB and MLWPCB in their decomposition levels, kinetic behaviour and structural properties. The calculated activation energy (E A ) of SSWPCB is found to be lower than that of MLWPCB. Elemental analysis of SSWPCB determines to have high carbon content in contrast to MLWPCB and differences in materials properties have significant influence on kinetics, which is ceramic rich, proving to have differences in the physicochemical properties. These high temperature transformation studies and associated analytical investigations provide fundamental understanding of different WPCB and its major variations. Copyright © 2015 Elsevier Ltd. All rights reserved.

Films prepared from electrosterically stabilized nanocrystalline cellulose.

PubMed

Yang, Han; Tejado, Alvaro; Alam, Nur; Antal, Miro; van de Ven, Theo G M

2012-05-22

Electrosterically stabilized nanocrystalline cellulose (ENCC) was modified in three ways: (1) the hydroxyl groups on C2 and C3 of glucose repeat units of ENCC were converted to aldehyde groups by periodate oxidation to various extents; (2) the carboxyl groups in the sodium form on ENCC were converted to the acid form by treating them with an acid-type ion-exchange resin; and (3) ENCC was cross-linked in two different ways by employing adipic dihydrazide as a cross-linker and water-soluble 1-ethyl-3-[3-(dimethylaminopropyl)] carbodiimide as a carboxyl-activating agent. Films were prepared from these modified ENCC suspensions by vacuum filtration. The effects of these three modifications on the properties of films were investigated by a variety of techniques, including UV-visible spectroscopy, a tensile test, thermogravimetric analysis (TGA), the water vapor transmission rate (WVTR), and contact angle (CA) studies. On the basis of the results from UV spectra, the transmittance of these films was as high as 87%, which shows them to be highly transparent. The tensile strength of these films was increased with increasing aldehyde content. From TGA and WVTR experiments, cross-linked films showed much higher thermal stability and lower water permeability. Furthermore, although the original cellulose is hydrophilic, these films also exhibited a certain hydrophobic behavior. Films treated by trichloromethylsilane become superhydrophobic. The unique characteristics of these transparent films are very promising for potential applications in flexible packaging and other high-technology products.

Hydrogenation of liquid natural rubber via diimide reduction in hydrazine hydrate/hydrogen peroxide system

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

Yusof, Muhammad Jefri Mohd; Jamaluddin, Naharullah; Abdullah, Ibrahim

Liquid natural rubber (LNR) with molecular weight of lower than 10{sup 5} and shorter polymeric chain than natural rubber was prepared. LNR was then hydrogenated via diimide reduction by oxidation of hydrazine hydrate with hydrogen peroxide. The unsaturated units of the rubber were converted into saturated hydrocarbon to strengthen the backbone of the polymer so it was able to resist thermal degradation. The results indicated that hydrogenation degree of the product (HLNR) could be extended to 91.2% conversion under appropriate conditions. The hydrogenated LNR (HLNR) was characterized using Fourier-Transform Infrared (FTIR) and Nuclear Magnetic Resonance (NMR) spectroscopy. The physical characteristicsmore » of HLNR were analyzed with Termogravimetric Analysis (TGA)« less

Investigation on the Enhanced Oxidation of Ferritic/Martensitic Steel P92 in Pure Steam

PubMed Central

Yuan, Juntao; Wu, Ximao; Wang, Wen; Zhu, Shenglong; Wang, Fuhui

2014-01-01

Oxidation of ferritic/martensitic steel P92 was investigated in pure oxygen and in pure steam at 600–800 °C by thermogravimetric analysis (TGA), optical microscopy (OM), scanning electron microscopy (SEM), and X-ray diffraction (XRD). The results showed that the oxidation of P92 was significantly enhanced and multilayer scale with an outer iron oxides layer formed in pure steam. At 700 °C, the gas switch markedly influenced the scaling kinetics and scale microstructure. It was supposed that the higher affinity of iron to steam would be attributed to the enhanced oxidation of P92 in pure steam, and the much easier transport of hydroxyl would account for the significant difference induced by gas switch. PMID:28788592

Fabrication of nanofiber mats from electrospinning of functionalized polymers

NASA Astrophysics Data System (ADS)

Oktay, Burcu; Kayaman-Apohan, Nilhan; Erdem-Kuruca, Serap

2014-08-01

Electrospinning technique enabled us to prepare nanofibers from synthetic and natural polymers. In this study, it was aimed to fabricate electrospun poly(vinyl alcohol) (PVA) based nanofibers by reactive electrospinning process. To improve endurance of fiber toward to many solvents, PVA was functionalized with photo-crosslinkable groups before spinning. Afterward PVA was crosslinked by UV radiation during electrospinning process. The nanofiber mats were characterized by scanning electron microscopy (SEM). The results showed that homogenous, uniform and crosslinked PVA nanofibers in diameters of about 200 nm were obtained. Thermal stability of the nanofiber mat was investigated with thermal gravimetric analysis (TGA). Also the potential use of this nanofiber mats for tissue engineering was examined. Osteosarcoma (Saos) cells were cultured on the nanofiber mats.

Fire-retardant decorative inks for aircraft interiors

NASA Technical Reports Server (NTRS)

Kourtides, D. A.; Nir, Z.; Mikroyannidis, J. A.

1985-01-01

Commercial and experimental fire retardants were screened as potential fire retardants for acrylic printing inks used on aircraft interior sandwich panels. The fire retardants are selected according to their physical properties and their thermostabilities. A criterion for selecting a more stable fire retardant is established. Thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) are used to determine thermostabilities. Results show that the fire retardant formulations are more thermally stable than the acrylic ink control. It is determined that an ink formulation containing a brominated phenol and carboxy-terminated butadiene acrylonitrile which has been modified with a brominated polymeric additive (BPA), yields the highest limiting oxygen index (LOI) of all the compounds tested. All of the fire-retardant formulations have a higher oxygen index than the baseline acrylic ink.

Preparation of poly (arylene ether nitrile)/NzdFeB composite film with excellent thermal properties and tensile strength

NASA Astrophysics Data System (ADS)

Pan, Hai; Xu, Mingzhen; Liu, Xiaobo

2017-12-01

PEN/NdFeB composite films were prepared by the solution casting method. The thermal properties, fracture morphology and tensile strength of the composite films were tested by DSC, TGA, SEM and electromechanical universal testing machine, respectively. The results reveal that the composite film has good thermal properties and tensile strength. Glass-transition temperature and decomposition temperatures at weight loss of 5% ot the composite films retain at 166±1 C and 462±4 C, respectively. The composite film with 5 wt.% NdFeB has the best tensile strength value for 100.5 MPa. In addition, it was found that the NdFeB filler was well dispersed in PEN matrix by SEM analysis.

Multinuclear solid film state NMR studies of metal oxide catalysts and minerals

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

Maxwell, R.S.; Stec, D.F.; Ellis, P.D.

1996-10-01

Several of our investigations of heterogeneous process by novel NMR experiments and analyses are reviewed and the utility and limitations of NMR spectroscopy for these areas discussed. Out studies have included the following: dynamics and arrangements of proton-containing adsorbates, primarily Bronsted acid sites and water, on the surface of zirconia and alumina catalysts; hydrogen dynamics and coordinates in synthetic aluminum oxyhydroxides; phase separation and crystallinity of synthetic minerals. In combination with the complementary results obtained in our laboratory via infrared spectroscopy, thermal analysis (primarily TGA and DSC), and catalytic activity measurements, these NMR data provide unique and valuable information onmore » atomic and molecular dynamics, identities, and structures without requiring pristine, single crystal specimens.« less

Thermal properties of silica-filled high density polyethylene composites compatibilized with glut palmitate

NASA Astrophysics Data System (ADS)

Samsudin, Dalina; Ismail, Hanafi; Othman, Nadras; Hamid, Zuratul Ain Abdul

2017-07-01

A study of thermal properties resulting from the utilization of Glut Palmitate (GP) on the silica filled high density polyethylene (HDPE) composites was carried out. The composites with the incorporation of GP at 0.5, 1.0, 2.0 and 3.0 phr were prepared by using an internal mixer at the temperature 180 °C and the rotor speed of 50 rpm. The thermal behaviours of the composites were then investigated using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). It was found that the crystallinity and the thermal stability of the composites increased with the incorporation of GP. The highest crystallinity contents and decomposition temperatures were observed at the 1 phr GP loading.

Multiple functionalization of multi-walled carbon nanotubes with carboxyl and amino groups

NASA Astrophysics Data System (ADS)

Zhao, Zhiyuan; Yang, Zhanhong; Hu, Youwang; Li, Jianping; Fan, Xinming

2013-07-01

In this paper, carboxyl and amino groups have been introduced onto the surface of the multi-walled carbon nanotubes (MWCNTs) by the mixed acid treatment and the diazonium reaction, respectively. The presence of multifunctionality groups on the MWCNTs has been characterized by Fourier transform infrared (FT-IR) spectroscopy, thermogravimetric (TGA) analysis, Raman spectra, scanning electron microscopy (SEM) and energy dispersive X-ray spectrum (EDS). The multifunctionalized carbon nanotubes were further utilized to react with acetyl chloride and ethylenediamine (EDA). The formation of the amide bond in the grafting reaction has been confirmed by FT-IR spectroscopy. The result indicates that the further grafting is successful. The multifunctionalized MWCNTs can be a new versatile platform for many interesting applications.

Hydroxyapatite-alginate nanocomposite as drug delivery matrix for sustained release of ciprofloxacin.

PubMed

Venkatasubbu, G Devanand; Ramasamy, S; Ramakrishnan, V; Kumar, J

2011-12-01

Hydroxyapatite is a bioceramic which has a wide range of medical application for bone diseases. To enhance its usage, we have prepared ciprofloxacin loaded nano hydroxyapatite (HA) composite with a natural polymer, alginate, using wet chemical method at low temperature. The prepared composites were analyzed by various physicochemical methods. The results show that the nano HA crystallites are well intact with the alginate macromolecules. For the composite system FT-IR and micro Raman results are reported in this paper. Studies on the drug loading and drug release have been done. The drug is pre-adsorbed onto the ceramic particle before the formation of composite. The thermal behavior of composite has been studied using thermo gravimetric analysis (TGA). This work, reports that the nanocomposite prepared under optimum condition could prolong the release of ciprofloxacin compared with the ciprofloxacin loaded hydroxyapatite.

Alkaline modified oil shale fly ash: optimal synthesis conditions and preliminary tests on CO2 adsorption.

PubMed

Reinik, Janek; Heinmaa, Ivo; Kirso, Uuve; Kallaste, Toivo; Ritamäki, Johannes; Boström, Dan; Pongrácz, Eva; Huuhtanen, Mika; Larsson, William; Keiski, Riitta; Kordás, Krisztián; Mikkola, Jyri-Pekka

2011-11-30

Environmentally friendly product, calcium-silica-aluminum hydrate, was synthesized from oil shale fly ash, which is rendered so far partly as an industrial waste. Reaction conditions were: temperature 130 and 160°C, NaOH concentrations 1, 3, 5 and 8M and synthesis time 24h. Optimal conditions were found to be 5M at 130°C at given parameter range. Original and activated ash samples were characterized by XRD, XRF, SEM, EFTEM, (29)Si MAS-NMR, BET and TGA. Semi-quantitative XRD and MAS-NMR showed that mainly tobermorites and katoite are formed during alkaline hydrothermal treatment. Physical adsorption of CO(2) on the surface of the original and activated ash samples was measured with thermo-gravimetric analysis. TGA showed that the physical adsorption of CO(2) on the oil shale fly ash sample increases from 0.06 to 3-4 mass% after alkaline hydrothermal activation with NaOH. The activated product has a potential to be used in industrial processes for physical adsorption of CO(2) emissions. Copyright © 2011 Elsevier B.V. All rights reserved.

Novel Isoniazid cocrystals with aromatic carboxylic acids: Crystal engineering, spectroscopy and thermochemical investigations

NASA Astrophysics Data System (ADS)

Diniz, Luan F.; Souza, Matheus S.; Carvalho, Paulo S.; da Silva, Cecilia C. P.; D'Vries, Richard F.; Ellena, Javier

2018-02-01

Four novel cocrystals of the anti-tuberculosis drug Isoniazid (INH), including two polymorphs, with the aromatic carboxylic acids p-nitrobenzoic (PNBA), p-cyanobenzoic (PCNBA) and p-aminobenzoic (PABA) were rationally designed and synthesized by solvent evaporation. Aiming to explore the possible supramolecular synthons of this API, these cocrystals were fully characterized by X-ray diffraction (SCXRD, PXRD), spectroscopic (FT-IR) and thermal (TGA, DSC, HSM) techniques. The cocrystal formation was found to be mainly driven by the synthons formed by the pyridine and hydrazide moieties. In both INH-PABA polymorphs, the COOH acid groups are H-bonded to pyridine and hydrazide groups giving rise to the acid⋯pyridine and acid⋯hydrazide heterosynthons. In INH-PNBA and INH-PCNBA cocrystals these acid groups are only related to the pyridine moiety. In addition to the structural study, supramolecular and Hirshfeld surface analysis were also performed based on the structural data. The cocrystals were identified from the FT-IR spectra and their thermal behaviors were studied by a combination of DSC, TGA and HSM techniques.

Facile Synthesis of Calcium Borate Nanoparticles and the Annealing Effect on Their Structure and Size

PubMed Central

Erfani, Maryam; Saion, Elias; Soltani, Nayereh; Hashim, Mansor; Wan Abdullah, Wan Saffiey B.; Navasery, Manizheh

2012-01-01

Calcium borate nanoparticles have been synthesized by a thermal treatment method via facile co-precipitation. Differences of annealing temperature and annealing time and their effects on crystal structure, particle size, size distribution and thermal stability of nanoparticles were investigated. The formation of calcium borate compound was characterized by X-ray diffraction (XRD) and Fourier Transform Infrared spectroscopy (FTIR), Transmission electron microscopy (TEM), and Thermogravimetry (TGA). The XRD patterns revealed that the co-precipitated samples annealed at 700 °C for 3 h annealing time formed an amorphous structure and the transformation into a crystalline structure only occurred after 5 h annealing time. It was found that the samples annealed at 900 °C are mostly metaborate (CaB2O4) nanoparticles and tetraborate (CaB4O7) nanoparticles only observed at 970 °C, which was confirmed by FTIR. The TEM images indicated that with increasing the annealing time and temperature, the average particle size increases. TGA analysis confirmed the thermal stability of the annealed samples at higher temperatures. PMID:23203073

Interference of condensed tannin in lignin analyses of dry bean and forage crops.

PubMed

Marles, M A Susan; Coulman, Bruce E; Bett, Kirstin E

2008-11-12

Legumes with high concentrations of condensed tannin (pinto bean [Phaseolus vulgaris L.], sainfoin [Onobrychis viciifolia Scop.], and big trefoil [Lotus uliginosus Hoff.]), were compared to a selection of forages, with low or zero condensed tannin (smooth bromegrass [ Bromus inermis Leyss], Lotus japonicus [Regel] K. Larsen, and alfalfa [Medicago sativa L.]), using four methods to estimate fiber or lignin. Protocols were validated by using semipurified condensed tannin polymers in adulteration assays that tested low-lignin tissue with polyphenolic-enriched samples. The effect on lignin assay methods by condensed tannin concentration was interpreted using a multivariate analysis. There was an overestimation of fiber or lignin in the presence of condensed tannin in the acid detergent fiber (ADF) and Klason lignin (KL) assays compared to that in the thioglycolic acid (TGA) and acid detergent lignin (ADL) methods. Sulfite reagents (present in TGA lignin method) or sequential acidic digests at high temperatures (ADF followed by ADL) were required to eliminate condensed tannin. The ADF (alone) and KL protocols are not recommended to screen nonwoody plants, such as forages, where condensed tannin has accumulated in the tissue.

Direct synthesis of carbon nanofibers from South African coal fly ash

NASA Astrophysics Data System (ADS)

Hintsho, Nomso; Shaikjee, Ahmed; Masenda, Hilary; Naidoo, Deena; Billing, Dave; Franklyn, Paul; Durbach, Shane

2014-08-01

Carbon nanofibers (CNFs), cylindrical nanostructures containing graphene, were synthesized directly from South African fly ash (a waste product formed during the combustion of coal). The CNFs (as well as other carbonaceous materials like carbon nanotubes (CNTs)) were produced by the catalytic chemical vapour deposition method (CCVD) in the presence of acetylene gas at temperatures ranging from 400°C to 700°C. The fly ash and its carbonaceous products were characterized by transmission electron microscopy (TEM), thermogravimetric analysis (TGA), laser Raman spectroscopy and Brunauer-Emmett-Teller (BET) surface area measurements. It was observed that as-received fly ash was capable of producing CNFs in high yield by CCVD, starting at a relatively low temperature of 400°C. Laser Raman spectra and TGA thermograms showed that the carbonaceous products which formed were mostly disordered. Small bundles of CNTs and CNFs observed by TEM and energy-dispersive spectroscopy (EDS) showed that the catalyst most likely responsible for CNF formation was iron in the form of cementite; X-ray diffraction (XRD) and Mössbauer spectroscopy confirmed these findings.

Electrochemical modelling of QD-phospholipid interactions.

PubMed

Zhang, Shengwen; Chen, Rongjun; Malhotra, Girish; Critchley, Kevin; Vakurov, Alexander; Nelson, Andrew

2014-04-15

The aggregation of quantum dots (QDs) and capping of individual QDs affects their activity towards biomembrane models. Electrochemical methods using a phospholipid layer on mercury (Hg) membrane model have been used to determine the phospholipid monolayer activity of thioglycollic acid (TGA) coated quantum dots (QDs) as an indicator of biomembrane activity. The particles were characterised for size and charge. The activity of the QDs towards dioleoyl phosphatidylcholine (DOPC) monolayers is pH dependent, and is most active at pH 8.2 within the pH range 8.2-6.5 examined in this work. This pH dependent activity is the result of increased particle aggregation coupled to decreasing surface charge emanating from the TGA carboxylic groups employed to stabilize the QD dispersion in aqueous media. Capping the QDs with CdS/ZnS lowers the particles' activity to phospholipid monolayers. Copyright © 2014 Elsevier Inc. All rights reserved.

Fluorescence Determination of Warfarin Using TGA-capped CdTe Quantum Dots in Human Plasma Samples.

PubMed

Dehbozorgi, A; Tashkhourian, J; Zare, S

2015-11-01

In this study, some effort has been performed to provide low temperature, less time consuming and facile routes for the synthesis of CdTe quantum dots using ultrasound and water soluble capping agent thioglycolic acid. TGA-capped CdTe quantum dots were characterized through x-ray diffraction, transmission electron microscopy, Fourier transform infrared, ultraviolet-visible and fluorescence spectroscopy. The prepared quantum dots were used for warfarin determination based on the quenching of the fluorescence intensity in aqueous solution. Under the optimized conditions, the linear range of quantum dots fluorescence intensity versus the concentration of warfarin was 0.1-160.0 μM, with the correlation coefficient of 0.9996 and a limit of detection of 77.5 nM. There was no interference to coexisting foreign substances. The selectivity of the sensor was also tested and the results show that the developed method possesses a high selectivity for warfarin.

Preparation and enhanced properties of polyaniline/grafted intercalated ZnAl-LDH nanocomposites

NASA Astrophysics Data System (ADS)

Hu, Jinlong; Gan, Mengyu; Ma, Li; Zhang, Jun; Xie, Shuang; Xu, Fenfang; Shen, JiYue Zheng Xiaoyu; Yin, Hui

2015-02-01

The polymeric nanocomposites (PANI/AD-LDH) were prepared by in situ polymerization based on polyaniline (PANI) and decavanadate-intercalated and γ-aminopropyltriethoxysilane (APTS)-grafted ZnAl-layered double hydroxide (AD-LDH). FTIR and XRD studies confirm the grafting of APTS with decavanadate-intercalated LDH (D-LDH). The extent of grafting (wt%) has also been estimated on the basis of the residue left in nitrogen atmosphere at 800 °C in TGA. SEM and XPS studies show the partial exfoliation of grafted LDH in the PANI matrix and the interfacial interaction between PANI and grafted LDH, respectively. The grafted intercalated layered double hydroxide in reinforcing the properties of the PANI nanocomposites has also been investigated by open circuit potential (OCP), tafel polarization curves (TAF), electrochemical impendence spectroscopy (EIS), salt spray test and TGA-DTA. The experimental results indicate that the PANI/AD-LDH has a higher thermal stability and anticorrosion properties relative to the PANI.

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

Asha, S.; Sangappa,; Sanjeev, Ganesh, E-mail: ganeshanjeev@rediffmail.com

Radiation-induced changes in Bombyx mori silk fibroin (SF) films under electron irradiation were investigated and correlated with dose. SF films were irradiated in air at room temperature using 8 MeV electron beam in the range 0-150 kGy. Various properties of the irradiated SF films were studied using X-ray diffraction (XRD), Differential Scanning Calorimetry (DSC) and Thermogravimetric Analysis (TGA). Electron irradiation was found to induce changes in the physical and thermal properties, depending on the radiation dose.

Synthesis and characterization of titanium dioxide (TiO2) nanopowder

NASA Astrophysics Data System (ADS)

Munirah, S.; Nadzirah, Sh.; Khusaimi, Z.; Fazlena, H.; Rusop, M.

2018-05-01

Titanium dioxide (TiO2) powder was synthesized via sol-gel technique using Titanium tetraisopropoxide (TTIP) and ethanol as precursors. Acetylacetone, distilled water, polyethylene glycol (PEG) and stabilizers (glacial acetic acid and nitric acid) were then added to the solution. The solution was left for ageing for 24 hours and then dried into powder. The synthesized powders were characterized by X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR) and Thermogravimetric Analysis (TGA).

The effect of thermal pre-treatment of titanium hydride (TiH2) powder in argon condition

NASA Astrophysics Data System (ADS)

Franciska P., L.; Erryani, Aprilia; Annur, Dhyah; Kartika, Ika

2018-04-01

Titanium hydride (TiH2) powders are used to enhance the foaming process in the formation of a highly porous metallic material with a cellular structure. But, the low temperature of hydrogen release is one of its problems. The present study, different thermal pre-treatment temperatures were employed to investigate the decomposition behavior of TiH2 to retard or delay a hydrogen gas release process during foaming. As a foaming agent, TiH2 was subjected to various heat treatments prior at 450 and 500°C during 2 hours in argon condition. To study the formation mechanism, the thermal behavior of titanium hydride and hydrogen release are investigated by thermogravimetric analysis (TGA) and differential thermal analysis (DTA). The morphology of pre-treated titanium hydride powders were examined using Scanning Electron Microscope (SEM) while unsure mapping and elemental composition of the pre-treated powders processed by Energy Dispersive Spectroscopy (EDS). To study the phase formation was characterized by X-ray diffraction analysis (XRD). In accordance with the results, an increase in pre-treatment temperature of TiH2 to higher degrees are changing the process of releasing hydrogen from titanium hydride powder. DTA/TGA results showed that thermal pre-treatment TiH2 at 450°C, released the hydrogen gas at 560°C in heat treatment when foaming process. Meanwhile, thermal pre-treatment in TiH2 at 500°C, released the hydrogen gas at 670°C when foaming process. There is plenty of direct evidence for the existence of oxide layers that showed by EDS analysis obtained in SEM. As oxygen is a light element and qualitative proof shows that the higher pre-treatment temperature produces more and thicker oxygen layers on the surface of the TiH2 powder particles. It might the thickness of oxide layer are different from different pre-treatment temperatures, which leading to the differences in the decomposition temperature. But from SEM result that oxidation of the powder does not change the powder morphology. The oxidation process also confirmed by XRD result, which showed higher thermal pre-treatment TiH2, more oxide higher peak is formed. The oxide layer of TiH2 particles is responsible for the observed shift in decomposition temperature and can prepare the stable foam that stabilizes forming of cell walls and avoid their collapse at higher temperatures.

Characterization of electron-beam-modified surface coated clay fillers and their influence on physical properties of rubbers

NASA Astrophysics Data System (ADS)

Ray, Sudip; Bhowmick, Anil K.; Sarma, K. S. S.; Majali, A. B.; Tikku, V. K.

2002-12-01

A novel process of surface modification of clay filler has been developed by coating this with an acrylate monomer, trimethylol propane triacrylate (TMPTA) or a silane coupling agent, triethoxy vinyl silane (TEVS) followed by electron beam irradiation. Characterization of these surface modified fillers has been carried out by Fourier-transform infrared analysis (FTIR), electron spectroscopy for chemical analysis (ESCA), wettability by dynamic wicking method measuring the rise of a liquid through a filler-packed capillary tube and water flotation test, scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), thermogravimetric analysis (TGA), and X-ray diffraction (XRD). Presence of the acrylate and the silane coupling agent on the modified fillers has been confirmed from FTIR, ESCA, and EDX studies, which has also been supported by TGA studies. The contact angle measurement by dynamic wicking method suggests improvement in hydrophobicity of the treated fillers, which is supported by water flotation test especially in the case of silanized clay. However, XRD studies demonstrate that the entire modification process does not affect the bulk properties of the fillers. Finally, both unmodified and modified clay fillers have been incorporated in styrene butadiene rubber (SBR) and nitrile rubber (NBR). Rheometric and mechanical properties reveal that there is a definite improvement using these modified fillers specially in the case of silanized clay compared to the control sample, probably due to successful enhancement in interaction between the treated clay and the base polymer.

Thermal Characterization and Flammability of Structural Epoxy Adhesive and Carbon/Epoxy Composite with Environmental and Chemical Degradation (Postprint)

DTIC Science & Technology

2012-01-01

this study). TGA scans show the thermal degradation of carbon/ epoxy composite by fuel additive at room temperature. Through Microscale Combustion...concerns regarding the durability of structural epoxy adhesive contaminated by hydraulic fluid or fuel additive , under simplified test conditions (no...higher than room tem- perature) or fuel additive (at all temperatures of this study). TGA scans show the thermal degradation of carbon/ epoxy composite

Isolation of the right subclavian artery in a patient with d-transposition of the great arteries.

PubMed

Arunamata, Alisa; Perry, Stanton B; Kipps, Alaina K; Vasanawala, Shreyas S; Axelrod, David M

2015-01-01

Isolation of the right subclavian artery (RSCA) is rare, and this finding in association with d-transposition of the great arteries (d-TGA) is extremely unusual. We present a case of an isolated RSCA in a newborn with d-TGA in whom the clinical presentation was diagnostic. We discuss the imaging modalities used to confirm the diagnosis, the embryological basis of the finding, and the surgical repair.

A fluorescent sensor based on thioglycolic acid capped cadmium sulfide quantum dots for the determination of dopamine

NASA Astrophysics Data System (ADS)

Kulchat, Sirinan; Boonta, Wissuta; Todee, Apinya; Sianglam, Pradthana; Ngeontae, Wittaya

2018-05-01

A fluorescent sensor based on thioglycolic acid-capped cadmium sulfide quantum dots (TGA-CdS QDs) has been designed for the sensitive and selective detection of dopamine (DA). In the presence of dopamine (DA), the addition of 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) and N-hydroxysuccinimide (NHS) activates the reaction between the carboxylic group of the TGA and the amino group of dopamine to form an amide bond, quenching the fluorescence of the QDs. The fluorescence intensity of TGA-CdS QDs can be used to sense the presence of dopamine with a limit of detection of 0.68 μM and a working linear range of 1.0-17.5 μM. This sensor system shows great potential application for dopamine detection in dopamine drug samples and for future easy-to-make analytical devices.

Evaluation of ZnSe(S) Quantum Dots on the Cell Viability of Prostate Cancer Cell (PC3)

NASA Astrophysics Data System (ADS)

Calderón-Ortiz, E. R.; Bailón-Ruiz, S.; Martínez-Ferrer, M.; Rodríguez-Orengo, J. F.; Perales-Pérez, O.

2018-05-01

Nanomedicine is described as the process of diagnosing, treating, and preventing disease using nanostructured materials to improve human health. Quantum dots (QDs) host suitable optical properties for light-driven therapies, e.g., photo-dynamic therapy (PDT), for cancer treatment. The efficacy of QDs-assisted PDT relies on the capability of QDs to generate reactive oxygen species, which can be enhanced by inducing structural defects at the atomic level. Furthermore, data concerning the applicability of QDs-PDT in medicine is scarce, particularly for prostate cancer cells (PC3). On this basis, and as a first step in this research, the present report focused on the direct aqueous-synthesis of water-stable ZnSe(S) QDs via a microwave-assisted synthesis approach in the presence of thioglycolic acid (TGA) and mercaptopropionic acid (MPA). XRD analysis confirmed the face centered cubic structure in host ZnS; the average crystallite size was estimated at 10 nm. The photoluminescence of MPA-capped ZnSe(S) showed a strong main emission peak around 363 nm and a trap emission, attributed to structural defects, centered on 450 nm. The photoluminescence spectrum for TGA-capped ZnSe(S) QDs exhibited only the band gap peak around 390 nm, suggesting the absence of major structural defects. In turn, cell viability assays TGA-capped ZnSe(S) were not toxic at concentrations up to 100 ppm, whereas MPA-capped ZnSe(S) evidenced cytotoxicity at a concentration of 10 ppm. The lethal dose (LD50) for the MPA-capped ZnSe(S) in the PC3 cell line was 36 ppm and 35 ppm for 24 h and 48 h, respectively.

A process for the development of strontium hydroxyapatite

NASA Astrophysics Data System (ADS)

Zahra, N.; Fayyaz, M.; Iqbal, W.; Irfan, M.; Alam, S.

2014-06-01

A procedure for the preparation of Strontium Hydroxyapatite is adapted to produce high purity and better homogeneity ceramic with good Crystallinity. The strontium substituted bone cement has potential for use in orthopedic surgeries. Ionic Strontium (Sr) in humans shares the same physiological pathway as calcium and can be deposited in the mineral structure of the bone. In the present study, a novel concept of preparing Sr-contained Hydroxyapatite bone cement by using a precipitation method is proposed to get an ideal biomaterial that possesses potential degradability and more excellent pharmacological effect. Chemical analysis, Fourier Transform Infra Red analysis and Thermogravimetric/ Differential Scanning Calorimetric studies were conducted on prepared Strontium Hydroxyapatite sample to characterize the incorporation of 15% Sr2+ into the crystal lattice of Hydroxyapatite. Strontium was quantitatively incorporated into Hydroxyapatite where its substitution for calcium provoked a linear shift of the infrared absorption bands of the hydroxyl and phosphate groups. Thus, the formation of Sr-HAp was confirmed by Chemical Analysis, FT-IR and TGA/DSC results.

Effect of surface modified kaolin on properties of polypropylene grafted maleic anhydride

NASA Astrophysics Data System (ADS)

Yang, Ni; Zhang, Zuo-Cai; Ma, Ning; Liu, Huan-Li; Zhan, Xue-Qing; Li, Bing; Gao, Wei; Tsai, Fang-Chang; Jiang, Tao; Chang, Chang-Jung; Chiang, Tai-Chin; Shi, Dean

To achieve reinforcement of mechanical and thermal performances of polypropylene (PP) product, this work aimed at fabrication of surface modified kaolin (M-kaolin) filled polypropylene grafted maleic anhydride (PP-g-MAH) composites with varying contents of fillers and investigation of their mechanical and thermal properties. And the prepared PP-g-MAH/M-kaolin composites were characterized by means of Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and thermogravimetric analysis (TGA). Fracture analysis by SEM showed M-kaolin particles were well dispersed in the PP-g-MAH matrix. Mechanical behaviors were determined by tensile strength, tensile strain at break and impact strength analysis. Impact strength of PP-g-MAH/2 wt% M-kaolin composites was improved up to 30% comparing with unfilled composites. Thermostability had been found enhanced when M-kaolin added. The results revealed PP-g-MAH/M-kaolin composites showed the optimal thermal and mechanical properties when 2 wt% of M-kaolin was added.

Synthesis and characterization of CdO nano particles by the sol-gel method

NASA Astrophysics Data System (ADS)

Vadgama, V. S.; Vyas, R. P.; Jogiya, B. V.; Joshi, M. J.

2017-05-01

Cadmium Oxide (CdO) is an inorganic compound and one of the main precursors to other cadmium compounds. It finds applications in cadmium plating, storage batteries, in transparent conducting film, etc. Here, an attempt is made to synthesize CdO nano particles by sol-gel technique. The gel was prepared using cadmium nitrate tetra hydrate (Cd(NO3)2.4H2O) and aqueous ammonium hydroxide (NH4OH) as a precursor. The synthesized powder is further characterized by techniques like Powder X-ray diffraction (XRD), Transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR) and Thermal gravimetric analysis (TGA). Powder XRD analysis suggested the nano-crystalline nature of the sample with the cubic crystal system. Nano scaled particles of spherical morphology with the size ranging from 50-100 nm are observed from TEM images. While, FT-IR study is used to confirm the presence of different functional groups. Thermo-gravimetric analysis suggests the highly thermally stable nature of the samples. The results are discussed.

Combustion properties, water absorption and grindability of raw/torrefied biomass pellets and Silantek coal

NASA Astrophysics Data System (ADS)

Matali, Sharmeela; Rahman, Norazah Abdul; Idris, Siti Shawaliah; Yaacob, Nurhafizah

2017-12-01

Torrefaction, also known as mild pyrolysis, is proven to convert raw biomass into a value-added energy commodity particularly for application in combustion and co-firing systems with improved storage and handling properties. This paper aims to compare the characteristics of Malaysian bituminous coal i.e. Silantek coal with raw and torrefied biomass pellet originated from oil palm frond and fast growing tree species, Leucaena Leucocephala. Biomass samples were initially torrefied at 300 °C for 60 minutes. Resulting torrefied biomass pellets were analysed using a number of standard fuel characterisation analyses i.e. elemental analysis, proximate analysis and calorific content (high heating values) experiments. Investigations on combustion characteristics via dynamic thermogravimetric analysis (TGA), grindability and moisture uptake tests were also performed on the torrefied biomass pellets. Better quality bio-chars were produced as compared to its raw forms and with optimal process conditions, torrefaction may potentially produces a solid fuel with combustion reactivity and porosity equivalent to raw biomass while having compatible energy density and grindability to coal.

Microwave-Assisted Synthesis of Goethite Nanoparticles Used for Removal of Cr(VI) from Aqueous Solution

PubMed Central

Kynicky, Jindrich; Adam, Vojtech

2017-01-01

The microwave-assisted synthesis of goethite nanoparticles has been studied. The samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), differential thermal analysis (DTA) and Brunauer–Emmett–Teller (BET) method. Goethite rod-like nanoparticles have been successfully synthesized in 10 min of microwave treating at 100 °C. Particle size is in the range from 30 to 60 nm in width and from 200 to 350 nm in length. BET analysis indicated that the surface area of the product is 158.31 m2g−1. The feasibility of Cr(VI) removal fromaqueous solution depends on the pH of the solution and contact time. The maximum adsorptionis reached at pH 4.0 and 540 min of contact time. The adsorption kinetics was analyzedby the pseudo-first- and second-order models and the results reveal that the adsorption process obeys the pseudo-second-order model. The adsorption data were fitted well with the Langmuir adsorption isotherm. PMID:28773142

Adsorption of diastase over natural halloysite nanotubes (HNTs)

NASA Astrophysics Data System (ADS)

Twaiq, F.; Chang, K. X.; Ling, J. Y. W.

2017-06-01

Adsorption of diastase over natural halloysite nanotubes is studied in order to evaluate the adsorption capacity of diastase. The halloysite surface characteristics were assessed using nitrogen adsorption, x-ray diffraction (XRD), thermal gravimetric analysis (TGA) and Fourier transformed infrared (FTIR). The surface area of the natural halloysite is found to be 51 m2·g-1, with total pore volume of 0.106 cm3·g-1. The natural halloysite has a basal spacing (d001) of 10 Å confirming the structure of the natural halloysite material. TGA results indicated that halloysite loses its interlayer water in the range of 30 to 105 °C and the dehydration in the structural layer above 150 °C. The dehydroxylation of halloysite has occurred at approximately 460 °C. The FTIR result of the thermally treated halloysite sample indicated that the bands observed are assigned to Si-O and Al-O bonds. The effects of solution pH and temperature were studied on the adsorption capacity and percent removal of diastase from the solution. The adsorption kinetic found to fit well with both the Pseudo first-order and Pseudo second-order models, and the values of the kinetic constant were found to be 0.173 min-1 and 0.00018 g·mg-1·min-1 respectively. The Langmuir isotherm model is found to fit well to the adsorption data and a kinetic value is found to be 0.00059 m3·g-1. The maximum adsorption capacity was found to be 370 mg·g-1, indicating the potential for applications of the natural nanostructured halloysite material as an effective adsorbent for diastase.

Identification of a novel selD homolog from Eukaryotes, Bacteria, and Archaea: Is there an autoregulatory mechanism in selenocysteine metabolism?

PubMed Central

Guimarães, M. Jorge; Peterson, David; Vicari, Alain; Cocks, Benjamin G.; Copeland, Neal G.; Gilbert, Debra J.; Jenkins, Nancy A.; Ferrick, David A.; Kastelein, Robert A.; Bazan, J. Fernando; Zlotnik, Albert

1996-01-01

Escherichia coli selenophosphate synthetase (SPS, the selD gene product) catalyzes the production of monoselenophosphate, the selenium donor compound required for synthesis of selenocysteine (Sec) and seleno-tRNAs. We report the molecular cloning of human and mouse homologs of the selD gene, designated Sps2, which contains an in-frame TGA codon at a site corresponding to the enzyme’s putative active site. These sequences allow the identification of selD gene homologs in the genomes of the bacterium Haemophilus influenzae and the archaeon Methanococcus jannaschii, which had been previously misinterpreted due to their in-frame TGA codon. Sps2 mRNA levels are elevated in organs previously implicated in the synthesis of selenoproteins and in active sites of blood cell development. In addition, we show that Sps2 mRNA is up-regulated upon activation of T lymphocytes and have mapped the Sps2 gene to mouse chromosome 7. Using the mouse gene isolated from the hematopoietic cell line FDCPmixA4, we devised a construct for protein expression that results in the insertion of a FLAG tag sequence at the N terminus of the SPS2 protein. This strategy allowed us to document the readthrough of the in-frame TGA codon and the incorporation of 75Se into SPS2. These results suggest the existence of an autoregulatory mechanism involving the incorporation of Sec into SPS2 that might be relevant to blood cell biology. This mechanism is likely to have been present in ancient life forms and conserved in a variety of living organisms from all domains of life. PMID:8986768

Early outcome for the primary arterial switch operation beyond the age of 3 weeks.

PubMed

Ismail, Sameh R; Kabbani, Mohamed S; Najm, Hani K; Abusuliman, Riyadh M; Elbarbary, Mahmoud

2010-07-01

The arterial switch operation (ASO) for neonates is the standard management for transposition of the great arteries (TGA) with an intact ventricular septum (IVS). Patients presenting for late ASO are at risk due to the possibility of left ventricle (LV) involution. This study aimed to assess the early postoperative course and outcome for children with TGA/IVS and still conditioned LV presenting for late primary ASO. A retrospective study of all TGA/IVS patients who underwent a primary ASO between March 2002 and March 2008 was conducted. The cases were divided into two groups. Group A included all the cases of early ASO repaired before the age of 3 weeks, whereas group B included all the preslected cases of late ASO repaired after the age of 3 weeks. The demographics, intensive care unit (ICU) parameters, complications, and short-term outcomes of the two groups were compared. The study enrolled of 91 patients: 64 patients (70%) in group A and 27 patients (30%) in group B. The mean age was 11 +/- 4 days in group A and 37 +/- 17 days in group B (P < 0.001). The two groups showed no significant statistical differences in ICU parameters, complications, or mortality. For patients with TGA/IVS, ASO still can be tolerated beyond the first month of life in selected cases. Provided the LV still is conditioned, age should not be a limitation for ASO.

Interdisciplinary landscape research in a medieval mound in one of the oldest Dutch towns, Vlaardingen, the Netherlands

NASA Astrophysics Data System (ADS)

de Ridder, Tim; Kluiving, Sjoerd; van Dasselaar, Marcel

2013-04-01

In Medieval times the city of Vlaardingen (the Netherlands) was strategically located on the confluence of three rivers, the Meuse, the Merwede and the Vlaarding. A church of early 8th century was already located here. In a short period of time Vlaardingen developed into an international trading place, the most important place in the former county of Holland. Starting from the 11th century the river Meuse threatened to flood the settlement, and as a reaction to it inhabitants started to raise the surface. This resulted eventually in an enormous mound, surface: 200 by 250 meter, built up in a four to five meter thick sequence of clay and manure in which organic rests of former occupation are extremely well preserved, e.g. wooden posts, mesh walls, but also leather objects. Early 2002 graves were found in the city centre, dating 1000-1050, in which not only the wooden coffins, but also the straw that covered the deceased. In human teeth DNA appeared to be well preserved, classified as the oldest in the nation, turning the church hill into a large database of human DNA. To secure the future of this vulnerable soil archive currently an extensive interdisciplinary research (mechanical drilling, grain size, TGA, archeological remains, osteology, hydrology, dating methods, micromorphology, microfauna, molluscs, diatoms) has started in 2011 to gain knowledge on the internal structure of the mound as well as on the well-preserved nature of the archaeological evidence. In this presentation the results of this large-scale project are demonstrated in a number of cross-sections with interrelated geological and archaeological stratification. Results of GSA (including end-member analysis EMMA), TGA, XRF and micromorphology analyses are presented. Distinction between natural and anthropogenic layering is made on the occurrence of chemical elements phosphor and potassium. Results of this research are also applied in the construction of the 3D model of the subsurface (this session, abstract Roozen et al.).

Cerebral Oximetry During Infant Cardiac Surgery: Evaluation of and Relationship to Early Postoperative Outcome

PubMed Central

Kussman, Barry D.; Wypij, David; DiNardo, James A.; Newburger, Jane W.; Mayer, John E.; del Nido, Pedro J.; Bacha, Emile A.; Pigula, Frank; McGrath, Ellen; Laussen, Peter C.

2009-01-01

Background We examined changes in cerebral oxygen saturation during infant heart surgery and its relationship to anatomic diagnosis and early outcome Methods Regional cerebral oxygen saturation (rSO2) was measured by near-infrared spectroscopy in 104 infants undergoing biventricular repair without aortic arch obstruction as part of a randomized trial of hemodilution to a hematocrit of 25% versus 35%. Results Prior to cardiopulmonary bypass (CPB), infants with tetralogy of Fallot had higher rSO2 values compared to those with D-transposition of the great arteries (D-TGA) or ventricular septal defect (P < 0.001). During CPB cooling, low flow and at the termination of CPB, D-TGA subjects had the highest rSO2 values (P < 0.001). There were no significant associations between intraoperative rSO2 and early postoperative outcomes after adjustment for diagnosis. In 39 D-TGA subjects with ≥5 minutes of deep hypothermic circulatory arrest, there was no correlation between the rSO2 (91 ± 6%) or hematocrit (29.2 ± 5.5%) at the onset of arrest and the rate of decline in rSO2 during arrest. Conclusions Intraoperative rSO2 varies according to anatomic diagnosis but accounts for very little of the variance in early outcome. As measured by frontal near-infrared spectroscopy, higher levels of hematocrit and current perfusion techniques appear to provide an adequate oxygen reservoir prior to relatively short periods of deep hypothermic circulatory arrest. PMID:19299774

The structural studies of vanadium substituted lithium-bismuth-boro-tellurite glass

NASA Astrophysics Data System (ADS)

Madhu, A.; Eraiah, B.

2018-05-01

The structural studies of vanadium substituted lithium-bismuth-boro-tellurite glass is successfully prepared and certain analysis like XRD,FTIR,DTA/TGA with density, molar volume are done. The amorphous phase has been identified based on X-ray diffraction analysis. The vanadium oxide plays the role as a glass-modifier and influences on BO3 ↔ BO4 conversion. The observed nonlinear variation in Tg with vanadium oxide increase, it reflects structural changes. The nonlinear variation of density and molar volume can be attributed to vanadium oxide incorporation have increased the number of Non-bridging oxygen (NBO'S).

Synthesis and Thermal Analysis of Nano-Aluminum/Fluorinated Polyurethane Elastomeric Composites for Structural Energetics.

PubMed

Zhang, Xianyu; Kim, Jin Seuk; Kwon, Younghwan

2017-04-01

Here we describe the synthesis of polyurethane (PU)-based energetic nanocomposites loaded with nano-aluminum (n-Al) particles. The energetic nanocomposite was prepared by polyurethane reaction of poly(glycidyl azide-co-tetramethylene glycol) (PGT) prepolymers and IPDI/N-100 isocyanates with simultaneous catalyst-free azide-alkyne Click reaction in the presence of n-Al. Initial study carried out with various n-Al/fluorinated PGT blends and demonstrated the potential of fluorinated PGT prepolymer for an energetic PU matrix. Thermal analysis of n-Al/fluorinated PGT-based PU energetic nanocomposite was performed using DSC and TGA.

78 FR 73460 - Airworthiness Directives; the Boeing Company Airplanes

Federal Register 2010, 2011, 2012, 2013, 2014

2013-12-06

... America Code 29, Hydraulic Power. (e) Unsafe Condition This AD was prompted by reports of turbine wheel...-400ER series airplanes. This proposed AD was prompted by reports of turbine wheel bursts in the air driven pump (ADP) turbine gearbox assembly (TGA), which resulted in the release of high energy fragments...

Functionalization of Graphene Nanoplatelets Using Sugar Azide for Graphene/Epoxy Nanocomposites

DTIC Science & Technology

2014-06-20

temperature to 200°C in the single cantilever mode at a heating rate and frequency of 3°C/min and 1 Hz, respectively. Thermogravimetric analysis (TGA) of...14. ABSTRACT We report a covalent functionalization of graphene nanoparticles (GnPs) employing 2,3,4-Tri-O-acetyl-β-D-xylopyranosyl azide...and glass transition temperature (~10C) compared to an un-functionalized GnP based epoxy composite. 15. SUBJECT TERMS Graphene nanoparticles

Incipient corrosion behavior of Haynes 230 under a controlled reducing atmosphere at high temperatures

NASA Astrophysics Data System (ADS)

Tung, Hsiao-Ming; Stubbins, James F.

2012-08-01

In situ thermogravimetry analysis (TGA) was used to investigate the incipient corrosion behavior of alloy 230 exposed under a reducing environment in a temperature range of 850-1000 °C. Both oxidation and loss of alloying elements of alloy 230 were observed to occur concurrently in these conditions. The surface oxide which formed on the substrate does not appear to be as effective in providing a protective layer during the incipient corrosion period.