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Magnani, F., A. Nolè, F. Ripullone et J. Grace. « Growth patterns of Pinus sylvestris across Europe : a functional analysis using the HYDRALL model ». iForest - Biogeosciences and Forestry 2, no 5 (15 octobre 2009) : 162–71. http://dx.doi.org/10.3832/ifor0516-002.
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Murukan, Greeshma, et Murugan K. « COMPOSITION OF PURIFIED ANTHOCYANIN ISOLATED FROM TEAK AND IT’S IN VITRO ANTIOXIDANT ACTIVITY ». International Journal of Pharmacy and Pharmaceutical Sciences 9, no 9 (22 juillet 2017) : 258. http://dx.doi.org/10.22159/ijpps.2017v9i9.19517.
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Objective: The present study evaluates purification, characterization of anthocyanin from in vitro culture of teak and its antioxidant potential.Methods: Anthocyanin was extracted from in vitro culture, purified by using amber lite XAD column and fractionated by Liquid chromatography mass spectrometry (LC-MS/MS). Various antioxidant assays were carried such as 2,2-diphenyl-1-picryl-hydrazyl-hydrate (DPPH), 2,2'-azino-bis-3-ethyl-benzothiazoline-6-sulphonic acid (ABTS), Oxygen radical absorbance capacity (ORAC), Nitric oxide (NO) and Hydrogen peroxide (H2O2).Results: Liquid chromatography mass spectrometry (LC-MS/MS) revealed the major fraction as cyanidin 3-(2-xylosyl-rutinoside) with unknown peaks. The amount of anthocyanin was 15.23 mg/g monomeric anthocyanin. Further, the potential antioxidant capacity of the teak anthocyanin was comparable to common vegetables and fruits. Similarly, high correlations of anthocyanin with antioxidant activity, such as oxygen radical absorbance capacity (ORAC), 2,2'-azino-bis-3-ethyl-benzothiazoline-6-sulphonic acid (ABTS), and 2,2-diphenyl-1-picryl-hydrazyl-hydrate (DPPH) (r = 0.95, 0.93, and 0.80) were found.Conclusion: The high anthocyanins content and potential antioxidant activity suggests that teak anthocyanin may be applied in the food industry as a good source of natural pigments
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Yao, Kaiyong, Luyi Jiang, Jianxin Liu, Diming Wang, Hongyun Liu et Daxi Ren. « Effect of Yellow Wine Lees Supplementation on Milk Antioxidant Capacity and Hematological Parameters in Lactating Cows under Heat Stress ». Animals 11, no 9 (9 septembre 2021) : 2643. http://dx.doi.org/10.3390/ani11092643.
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Fifteen multiparous lactating Chinese Holstein dairy cows were used in a replicated 3 × 3 Latin Square Design to evaluate the effect of total mixed rations (TMR) containing unfermented and fermented yellow wine lees (YWL) on the oxidative status of heat-stressed lactating cows and the oxidative stability of the milk and milk fatty acids they produced. Cows were fed with three isonitrogenous and isocaloric diets as follows: (1) TMR containing 18% soybean meal, (2) TMR containing 11% unfermented YWL (UM), and (3) TMR containing 11% fermented YWL (FM). The rectal temperature (at 1300 h) and respiratory rate were higher in control cows than in cows fed UM or FM. Both types of YWL were greater in total phenolic and flavonoid contents, reducing power, and radical scavenging abilities than soybean meal. Cows fed UM or FM had higher blood neutrophil, white blood cell, and lymphocyte counts, as well as lower plasma malondialdehyde level, higher plasma superoxide dismutase, glutathione peroxidase, and 2,2-diphenyl-1-picryl-hydrazyl-hydrate levels, and higher total antioxidant capacity in the plasma than those fed control diet. The proportion of milk unsaturated fatty acids was higher and that of saturated fatty acids was lower in UM- and FM-fed animals than in the control animals. Milk from UM- and FM-fed cows had lower malondialdehyde content but higher 2,2-diphenyl-1-picryl-hydrazyl-hydrate content than the control cows. In conclusion, feeding TMR containing UM and FM to cows reduced both the oxidative stress in heat-stressed cows and improved the oxidative capacity of their milk.
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BEEK, H. C. A., P. M. HEERTJES, C. HOUTEPEN et D. RETZLOFF. « Formation of Hydrazyl Radicals and Hydrazo Compounds by Photoreduction of Azo Dyes ». Journal of the Society of Dyers and Colourists 87, no 3 (22 octobre 2008) : 87–92. http://dx.doi.org/10.1111/j.1478-4408.1971.tb03006.x.
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Batubara, R., T. I. Hanum et O. Affandi. « GC-MS analysis of young and mature wild agarwood leaves (Aquilaria malaccensis Lamk) and its antioxidant potential ». IOP Conference Series : Earth and Environmental Science 912, no 1 (1 novembre 2021) : 012038. http://dx.doi.org/10.1088/1755-1315/912/1/012038.
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Abstract Agarwood grows wildly in the nature and its leaves may be utilized as raw materials for agarwood tea, especially from Aquilaria species. The study was conducted to determine the chemical compounds in the young and mature leaves of wild gaharu (Aquilaria malaccensis Lamk). Chemical compounds were detected using pyrolysis gas chromatography mass spectrometry (py-GCMS) while antioxidant capacity of the leaf extracts was assayed using 2,2-diphenyl-1-picryl-hydrazyl-hydrate (DPPH) free radical method. The results obtained a total of 30 chemical compounds in agarwood leaves extract with different composition between young and mature leaves. The agarwood leaves extracts displayed strong antioxidative capacity with a main compound namely octadecanoid acid or stearic acid.
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Heijkoop, G., et H. C. A. van Beek. « Decomposition and disproportionation of hydrazyl radicals and hydrazo compounds derived from azo dyes ». Recueil des Travaux Chimiques des Pays-Bas 95, no 1 (2 septembre 2010) : 6–10. http://dx.doi.org/10.1002/recl.19760950103.
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AlNeyadi, Shaikha S., Naheed Amer, Tony G. Thomas, Ruba Al Ajeil, Priya Breitener et N. Munawar. « Synthesis, Characterization, and Antioxidant Activity of Some 2-Methoxyphenols derivatives ». Heterocyclic Communications 26, no 1 (27 septembre 2020) : 112–22. http://dx.doi.org/10.1515/hc-2020-0112.
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AbstractOxidative stress is a causative factor in the pathophysiology of numerous diseases, such as diabetes, atherosclerosis, cancer, and neurodegenerative and cardiovascular diseases. Therapeutic antioxidants are promising candidates for preventing and treating conditions in which oxidative stress is a contributing factor. In this study, we report the design, synthesis and antioxidant activity of six compounds containing the 2-methoxyphenol moiety core structure. The synthesized derivatives were characterized using 1H NMR, 13C NMR, Fourier-transform infrared (FT-IR), and elemental analysis spectroscopy. The antioxidant properties of the compounds were evaluated using the 2,2-diphenyl-1-picryl-hydrazyl-hydrate (DPPH), 2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid (ABTS), and oxygen radical absorbance capacity (ORAC) assay. New phenolic acid-derived compounds with antioxidant activity were identified.
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Al-Mashhadani, Asia H. « Study of in vitro and in vivo free radical scavenging activity for radioprotection of cerium oxide nanoparticles ». Iraqi Journal of Physics (IJP) 15, no 35 (2 octobre 2018) : 40–47. http://dx.doi.org/10.30723/ijp.v15i35.52.
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Nanoceria have shown numerous unique characteristics, such as biocompatibility and are excellent agents for biological applications. The aim of this study is to investigate cerium oxide nanoparticles for 2, 2- diphenyl-1-picryl-hydrazyl-hydrate (DPPH) free radical scavenging activity and their ability to offer protection against ionizing radiation. In vitro antioxidant activity study of nanoceria particles has shown good free radical scavenging activity for DPPH radical assayed within a concentration range of 0.01 to 0.05 g/l, at higher concentrations of nanoparticles showed reverse trend in absorbance and inhibition indicating this finite rang of concentration is suitable for scavenging free radicals, also nanoparticles were found to have significant antioxidant capacity and thus can be used as potential radical scavenger against deleterious damages caused by the free radicals. The results of histopathological examination showed effectiveness of CeO2 nanoparticles in radioprotection of skin cells in animal models during radiation exposure.
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Marinković, Jelena, Biljana Nikolić, Tatjana Marković, Milena Radunović, Jugoslav Ilić, Marko Bošković, Ana Ćirić et Dejan Marković. « Cymbopogon citratus essential oil : an active principle of nanoemulsion against Enterococcus faecalis root canal biofilm ». Future Microbiology 16, no 12 (août 2021) : 907–18. http://dx.doi.org/10.2217/fmb-2021-0081.
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Aim: The objective was to formulate and characterize the nanoemulsion based on Cymbopogon citratus oil, intended for use in infected teeth root canal therapy. The investigation of the antioxidant and antibiofilm potential toward Enterococcus faecalis was aimed as well. Materials & methods: Characterization of oil (by GC/MS analysis) and nanoemulsion (by dynamic light scattering instrument), and determination of antibacterial (by microdilution assay), antibiofilm (by crystal violet assay) and antioxidant properties (by 2,2-diphenyl-1-picryl-hydrazyl-hydrate and thiobarbituric acid assay methods) were provided. Antibiofilm efficacy of irrigation procedure including nanoemulsion was screened on extracted teeth (by CFU-counting assay). Results: Notable antibacterial and antibiofilm activity, both against forming and preformed biofilms of oil, was observed. Irrigation involved nanoemulsion showed remarkable antibiofilm potential. Both substances induced some antioxidant activity. Conclusion: Results encourage further research with the aim of application of the nanoemulsion in dental practice.
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Lee, Chang-Hyun, Hyo-Soon Shin, Dong-Hun Yeo, Gook-Hyun Ha et Sahn Nahm. « The Synthesis Mechanism of BaTiO3Nano Particle at Low Temperature by Hydrate Salt Method ». Journal of the Korean Institute of Electrical and Electronic Material Engineers 27, no 12 (1 décembre 2014) : 852–56. http://dx.doi.org/10.4313/jkem.2014.27.12.852.
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Mukundh Chaithanya, V. « Anti-inflammatory and cytotoxic effect of lycopene and raspberry in-situ gel ». Bioinformation 18, no 7 (31 juillet 2022) : 645–50. http://dx.doi.org/10.6026/97320630018645.
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Preparation of an in-situ gel containing lycopene and raspberry plant formulation and analysis of its anti-inflammatory and antioxidant effects is described. Lycopene is known for its anticancer and antioxidant activity. It induces apoptosis, thereby reducing the cancer cells, and also reduces the injury of cells due to oxidative activity. Similarly, raspberry also contains antioxidants properties which can help to reduce oxidative stress and chronic inflammation. This study includes extracts containing 25% of Raspberry and 10% lycopene, carboxymethyl cellulose, hydroxypropyl methyl cellulose, Carbopol, sodium chloride, and distilled water. This in-situ gel was then tested for antioxidant and anti-inflammatory assay using DPPH (2, diphenyl 1-picryl- hydrazyl- hydrate) and bovine serum albumin (BSA), antioxidant assay revealed that the inhibition percentage was more with 50 μL (61.3) of gel and anti-inflammatory assay showed significant results with 10 μL (90.2) of gel. In-situ gel containing lycopene and Raspberry has significant anti-inflammatory and antioxidant activity.
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H, Abdul Kaffoor, Muthuraj K et Arumugasamy K. « ANTIOXIDANT ACTIVITY OF LEAF EXTRACTS OF HEMIDESMUS INDICUS (L.) R.BR. (ASCLEPIADACEAE). » Asian Journal of Pharmaceutical and Clinical Research 10, no 6 (1 juin 2017) : 200. http://dx.doi.org/10.22159/ajpcr.2017.v10i6.17634.
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Objective: A number of Indian medicinal plants have been used for thousands of years in a traditional system of medicine. Hemidesmus indicus is an important member of the Asclepiadaceae family. It is an endemic to the southern Western Ghats, India. The aim of the study was to investigate the free radical scavenging activity of H. indicus. Methods: The aqueous and methanol leaf extracts of H. indicus were assayed for radical scavenging activity, using the stable free radical 2,2-diphenyl- 1-picryl-hydrazyl-hydrate and 2,2’-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid). Results: The results revealed that the IC50 values of aqueous extract of H. indicus were found to be higher than that of the other solvent extracts. The free radical scavenging activity of the plant extracts may be due to the presence of phytoconstituents. Conclusion: In all the methods, the aqueous extract has exhibited the good scavenging activity and this arises that the plant has a potential antioxidant agent.
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Nhu Hieu, Vo Mai, Tran Thi Thanh Van, Cao Thi Thuy Hang, Natalia P. Mischenko, Fedoreyev Sergey A. et Hai Bang Truong. « Polyhydroxynaphthoquinone Pigment From Vietnam Sea Urchins as a Potential Bioactive Ingredient in Cosmeceuticals ». Natural Product Communications 15, no 11 (novembre 2020) : 1934578X2097252. http://dx.doi.org/10.1177/1934578x20972525.
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In this study, valuable polyhydroxynaphthoquinone (PHNQ) pigments were recovered from sea urchin food waste and were investigated as a potential bioactive ingredient for cosmeceuticals. The crude PHNQ pigment extract from 4 Vietnam sea urchins, Diadema setosum, Diadema savignyi, Stomopneustes variolaris, and Tripneustes gratilla, exhibited effective 2,2-diphenyl-1-picryl-hydrazyl-hydrate scavenging activity, tyrosinase inhibitory activity, and antibacterial activity. The moisturizing cream with 0.5% of PHNQ pigments from D. setosum and Tripneustes gratilla sea urchins showed no dermal irritation over 14 days of mouse skin test. Four major active components in PHNQ were identified via high-performance liquid chromatography coupled with diode array detector and mass spectrometry. Echinochrome A contributed considerably to the antioxidant activity of the extracts while those containing echinochrome A and spinochrome E were significantly active against various bacteria. The promising results laid the foundation for establishing a novel process from food waste to innovative biomaterial and formulating eco-friendly skincare products with PHNQ components from sea urchins as precious ingredient.
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Diyan Ajeng RA, Rosida,. « PENENTUAN AKTIVITAS ANTIOKSIDAN DAN KADAR FENOL TOTAL PADA EKSTRAK KULIT BUAH PISANG (Musa acuminata Colla) ». JURNAL ILMIAH FARMASI AKADEMI FARMASI JEMBER 2, no 1 (28 janvier 2021) : 33–38. http://dx.doi.org/10.53864/jifakfar.v2i1.20.
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Antioksidan merupakan senyawa yang mampu menghambat oksidasi molekul lain. Tubuh tidak mempunyai sistem pertahanan antioksidatif yang berlebihan, sehingga tubuh membutuhkan antioksidan eksogen. Kekhawatiran terhadap efek samping antioksidan sintetik menjadikan antioksidan alami menjadi alternatif yang dipilih. Flavonoid merupakan senyawa fenolat (hidroksil fenolik) yang mampu bertindak sebagai antioksidan dan umumnya terdapat pada tanaman. Salah satu limbah tanaman yang mempunyai kandungan flavonoid adalah kulit buah pisang (Musa acuminata). Tujuan dari penelitian ini adalah untuk menetapkan kadar flavonoid total dan melakukan pengujian aktivitas antioksidan kulit buah pisang menggunakan diphenyl picryl hydrazil hydrate (DPPH) sebagai radikal bebas. Metode ekstraksi yang digunakan adalah remaserasi dengan pelarut etanol 96%. Penetapan kadar flavonoid total menggunakan katekin sebagai standar dan pengujian DPPH menggunakan metode spetrofotometri. Hasil penelitian menunjukkan kandungan flavonoid total ekstrak etanol kulit buah pisang sebesar 0,79 ± 0,03 %b/b, aktivitas antioksidan tertinggi dalam IC50 terhadap DPPH sebesar 70,41 mg/L.Kata Kunci : kulit buah pisang, flavonoid total, aktivitas antioksidan, IC50
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Yun, Rin, Benedict Prah et Kwangbin Lee. « CFD Modelling of CO₂ Hydrate Formation in the Presence of Additives ». Korean Journal of Air-Conditioning and Refrigeration Engineering 33, no 12 (31 décembre 2021) : 645–55. http://dx.doi.org/10.6110/kjacr.2021.33.12.645.
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M, Bazvand. « A New Inhibitor to Prevent Hydrate Formation ». Petroleum & ; Petrochemical Engineering Journal 5, no 1 (2021) : 1–6. http://dx.doi.org/10.23880/ppej-16000251.
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Due to the growing demand for energy as well as the depletion of shallow land reservoirs, it sounds more important to utilize deep sea reservoirs. Due to their special conditions, drilling and production of these reservoirs face more problems. The science that helps us avoiding problems during operation is called flow assurance. One of the important issues in flow assurance is to prevent formation of gas hydrates. One of gas hydrates preventing methods is to use of inhibitors. Using of inhibitors is a cost- effective and eco-friendly method; so, it is used more nowadays. This paper introduces a new hydrate inhibitor that has been developed from the modification of one of the most widely used inhibitors present in the industry, Poly Vinyl Pyrrolidone, to improve its efficiency. The main structure of the paper is about what is the gas hydrate and its prevention methods. Finally, compare different inhibitors with new one. The results show that hydrate formation time for all polymers is approximately the same, while a half of new inhibitor in compare with amount of others inhibitors causes the same results. This matter shows a double efficiency, and this means a saving of double Polymer consumption.
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Ganesh Somashekarachar, Arpita Goswami, Kannika Byadarahalli Ravindranath, Madan Kumar Shankar et Manju Nagaraja. « Antioxidant studies of 3-(5-(2,4-dichlorophenoxy)-3-methyl-1-phenyl-1Hpyrazole-4-yl)-1-(furan-2-yl)prop-2-en-1-one ». International Journal of Research in Pharmaceutical Sciences 12, no 2 (5 mai 2021) : 1375–78. http://dx.doi.org/10.26452/ijrps.v12i2.4693.
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Chalcones are flavonoid precursors, abundant in edible plants. The pyrazole moieties in chalcones show various pharmacological activities. Notably, Chalcone-based structures exhibit numerous pharmacological activities like antiinflammatory, antibacterial, antitumor, antioxidant functions because of having α, β-unsaturated ketone moiety. Such broad spectrum biological activities were also observed in several nitrogen containing heterocycles. Among the heterocyclic systems, pyrazole stand unique. All these observations led us to design and synthesize pyrazole fused hybrid thiophenechalcone molecule 3-(5-(2,4-dichlorophenoxy)-3-methyl-1-phenyl-1H-pyrazole-4-yl)-1-(furan-2-yl)prop-2-en-1-one (3a). The synthesis was performed using base catalyzed reaction of pyrazole aldehyde and acetyl furan. Further characterization of the molecule was done by spectroscopy and antioxidant studies. Spectroscopic methods included Fourier transform infrared (FTIR), nuclear magnetic resonance (NMR) and mass spectra (MS). The antioxidant potency of the compound was carried out based on the scavenging activity of 2,2-diphenyl-1-picryl-hydrazyl-hydrate (DPPH). This compound showed moderate free radical scavenging activity of 45.12 %.
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Khan, Azhar U., Masudulla Khan, Azmat Ali Khan, Aiman Parveen, Sajid Ansari et Mahboob Alam. « Effect of Phyto-Assisted Synthesis of Magnesium Oxide Nanoparticles (MgO-NPs) on Bacteria and the Root-Knot Nematode ». Bioinorganic Chemistry and Applications 2022 (8 août 2022) : 1–11. http://dx.doi.org/10.1155/2022/3973841.
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The root-knot nematode was examined using magnesium oxide nanoparticles (MgO-NPs) made from strawberries. The biologically synthesized MgO-NPs were characterized by UV, SEM, FTIR, EDS, TEM, and dynamic light scattering (DLS). Nanoparticles (NPs) were examined using scanning electron microscopy (SEM) and transmission electron microscopy (TEM) and shown to be spherical to hexagonal nanoparticles with an average size of 100 nm. MgO-NPs were tested on the root-knot nematode M. incognita (Meloidogynidae) and the plant pathogenic bacteria Ralstonia solanacearum. The synthesized MgO-NPs showed a significant inhibition of R. solanacearum and the root-knot nematode. MgO-NPs cause mortality and inhibit egg hatching of second-stage juveniles (J2) of M. incognita under the in vitro assay. This study aims to examine the biological activity of biogenic MgO-NPs. The findings marked that MgO-NPs may be utilized to manage R. solanacearum and M. incognita and develop effective nematicides. In addition, the antioxidant capacity of MgO-NPs was determined by using 2, 2-diphenyl-1-picryl-hydrazyl-hydrate (DPPH).
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Sinurat, Ellya, et Nurun Nisa Maulida. « Pengaruh Hidrolisis Fukoidan terhadap Aktivitasnya sebagai Antioksidan ». Jurnal Pascapanen dan Bioteknologi Kelautan dan Perikanan 13, no 2 (30 décembre 2018) : 123. http://dx.doi.org/10.15578/jpbkp.v13i2.522.
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Fukoidan merupakan jenis heteropolisakarida yang terdiri dari fukosa dan gugus ester sulfat sebagai penyusun utamanya. Salah satu sumber fukoidan adalah rumput laut cokelat. Telah dilakukan isolasi fukoidan dari rumput laut cokelat Sargassum crassifolium yang diperoleh dari Lampung Selatan. Penelitian ini bertujuan untuk mengetahui pengaruh hidrolisis fukoidan terhadap aktivitasnya sebagai antioksidan. Ekstraksi fukoidan menggunakan HCl 0,1 N. Selanjutnya proses optimasi hidrolisis fukoidan menggunakan TFA 1,5 M dengan variasi waktu 30, 60, 90 dan 120 menit pada suhu 121 oC. Untuk mengetahui karakteristik gugus fungsi crude fukoidan dan fukoidan hasil hidrolisis dilakukan dengan menggunakan Fourier Transform Infrared Spectrometer (FT-IR). Selanjutnya dilakukan karakterisasi fukoidan yang meliputi uji total polisakarida dan uji kadar sulfat. Uji antioksidan fukoidan dilakukan dengan metode 2,2-diphenyl-1-picryl-hydrazyl-hydrate (DPPH). Diperoleh rendemen fukoidan sebesar 23,82% dari berat rumput laut kering, total polisakarida dari crude fukoidan sebesar 50,69% dan kadar sulfatnya sebesar 19,44%. Dari hasil penelitian diperoleh waktu optimum hidrolisis fukoidan yaitu selama 90 menit dengan total polisakarida dan kandungan sulfatnya masing-masing 43,56% dan 13,09%. Diperoleh nilai IC50 crude fucoidan lebih tinggi dibandingkan dengan semua hasil hidrolisis fukoidan.
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Stasiłowicz, Anna, Natalia Rosiak, Ewa Tykarska, Maciej Kozak, Jacek Jenczyk, Piotr Szulc, Joanna Kobus-Cisowska et al. « Combinations of Piperine with Hydroxypropyl-β-Cyclodextrin as a Multifunctional System ». International Journal of Molecular Sciences 22, no 8 (18 avril 2021) : 4195. http://dx.doi.org/10.3390/ijms22084195.
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Piperine is an alkaloid that has extensive pharmacological activity and impacts other active substances bioavailability due to inhibition of CYP450 enzymes, stimulation of amino acid transporters and P-glycoprotein inhibition. Low solubility and the associated low bioavailability of piperine limit its potential. The combination of piperine with 2-hydroxypropyl-β-cyclodextrin (HP-β-CD) causes a significant increase in its solubility and, consequently, an increase in permeability through gastrointestinal tract membranes and the blood–brain barrier. X-ray powder diffraction (XRPD), differential scanning calorimetry (DSC), Fourier-transform infrared spectroscopy (FT-IR), nuclear magnetic resonance (NMR) were used to characterize interactions between piperine and HP-β-CD. The observed physicochemical changes should be combined with the process of piperine and CD system formation. Importantly, with an increase in solubility and permeability of piperine as a result of interaction with CD, it was proven to maintain its biological activity concerning the antioxidant potential (2,2-diphenyl-1-picryl-hydrazyl-hydrate assay), inhibition of enzymes essential for the inflammatory process and for neurodegenerative changes (hyaluronidase, acetylcholinesterase, butyrylcholinesterase).
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Lee, Sol, Han-Oh Park et Wonbeak Yoo. « Anti-Melanogenic and Antioxidant Effects of Cell-Free Supernatant from Lactobacillus gasseri BNR17 ». Microorganisms 10, no 4 (8 avril 2022) : 788. http://dx.doi.org/10.3390/microorganisms10040788.
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In recent years, there has been considerable interest in the use of cell-free supernatant of probiotics culture for nutritional and functional applications. In this study, we investigated the effect of the cell-free supernatant from Lactobacillus gasseri BNR17 (CFS) on anti-melanogenesis and reducing oxidative stress in B16-F10 murine melanoma cells and HaCaT human keratinocytes. Treatment with CFS significantly inhibited the production of extracellular and intracellular melanin without cytotoxicity during melanogenesis induced by the α-MSH in B16-F10 cells. The CFS dramatically reduced tyrosinase activity and the melanogenesis-related gene expression. Further, it showed antioxidative effects in a dose-dependent manner in DPPH (2,2-diphenyl-1-picryl-hydrazyl-hydrate) assays and significantly increased the mRNA levels of HO-1 and CAT in HaCaT cells. Furthermore, the CFS increased HO-1 and anti-oxidative-related gene expression during H2O2-induced oxidative stress in HaCaT cells. Together, this study suggests that the CFS reduces hyperpigmentation and inhibits oxidative stress, and thus can be used as a potential skincare product in the future.
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Montenegro, Iván, Jorge Moreira, Ingrid Ramírez, Fernando Dorta, Elizabeth Sánchez, Juan Felipe Alfaro, Manuel Valenzuela et al. « Chemical Composition, Antioxidant and Anticancer Activities of Leptocarpha rivularis DC Flower Extracts ». Molecules 26, no 1 (25 décembre 2020) : 67. http://dx.doi.org/10.3390/molecules26010067.
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An evaluation of antioxidant and anticancer activity was screened in Leptocarpha rivularis DC flower extracts using four solvents (n-hexane (Hex), dichloromethane (DCM), ethyl acetate (AcOEt), and ethanol (EtOH)). Extracts were compared for total extract flavonoids and phenol contents, antioxidant activity (2,2-diphenyl-1-picryl-hydrazyl-hydrate (DPPH), ferric reducing antioxidant potential (FRAP), total reactive antioxidant properties (TRAP) and oxygen radical absorbance capacity (ORAC)) across a determined value of reduced/oxidized glutathione (GSH/GSSG), and cell viability (the sulforhodamine B (SRB) assay). The most active extracts were analyzed by chromatographic analysis (GC/MS) and tested for apoptotic pathways. Extracts from Hex, DCM and AcOEt reduced cell viability, caused changes in cell morphology, affected mitochondrial membrane permeability, and induced caspase activation in tumor cell lines HT-29, PC-3, and MCF-7. These effects were generally less pronounced in the HEK-293 cell line (nontumor cells), indicating clear selectivity towards tumor cell lines. We attribute likely extract activity to the presence of sesquiterpene lactones, in combination with other components like steroids and flavonoids.
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Zhao, Jinhuan, Changling Liu, Qiang Chen, Changchun Zou, Yang Liu, Qingtao Bu, Jiale Kang et Qingguo Meng. « Experimental Investigation into Three-Dimensional Spatial Distribution of the Fracture-Filling Hydrate by Electrical Property of Hydrate-Bearing Sediments ». Energies 15, no 10 (12 mai 2022) : 3537. http://dx.doi.org/10.3390/en15103537.
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As a future clean energy resource, the exploration and exploitation of natural gas hydrate are favorable for solving the energy crisis and improving environmental pollution. Detecting the spatial distribution of natural gas hydrate in the reservoir is of great importance in natural gas hydrate exploration and exploitation. Fracture-filling hydrate, one of the most common types of gas hydrate, usually appears as a massive or layered accumulation below the seafloor. This paper aims to detect the spatial distribution variation of fracture-filling hydrate in sediments using the electrical property in the laboratory. Massive hydrate and layered hydrate are formed in the electrical resistivity tomography device with a cylindrical array. Based on the electrical resistivity tomography data during the hydrate formation process, the three-dimensional resistivity images of the massive hydrate and layered hydrate are established by using finite element forward, Gauss–Newton inversion, and inverse distance weighted interpolation. Massive hydrate is easier to identify than layered hydrate because of the big difference between the massive hydrate area and surrounding sediments. The diffusion of salt ions in sediments makes the boundary of massive hydrate and layered hydrate change with hydrate formation. The average resistivity values of massive hydrate (50 Ω⋅m) and layered hydrate (1.4 Ω⋅m) differ by an order of magnitude due to the difference in the morphology of the fracture. Compared with the theoretical resistivity, it is found that the resistivity change of layered hydrate is in accordance with the change tendency of the theoretical value. The formation characteristic of massive hydrate is mainly affected by the pore water distribution and pore microstructure of hydrate. The hydrate formation does not necessarily cause the increase in resistivity, but the increase of resistivity must be due to the formation of hydrate. The decrease of resistivity in fine-grains is not obvious due to the cation adsorption of clay particles. These results provide a feasible approach to characterizing the resistivity and growth characteristics of fracture-filling hydrate reservoirs and provide support for the in-situ visual detection of fracture-filling hydrate.
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Shirota, Hideyuki, et Susumu Ota. « Experimental Study on Dissociation Rate and Dissociation Limit Temperature of Methane Hydrate Pellets for Seaborne Transport of Natural Gas Hydrate Pellets ». Journal of The Japan Institute of Marine Engineering 45, no 6 (2010) : 899–906. http://dx.doi.org/10.5988/jime.45.899.
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Li, Sheng-Li, You-Hong Sun, Kai Su, Wei Guo et You-Hai Zhu. « Numerical simulation of CH4 hydrate formation in fractures ». Energy Exploration & ; Exploitation 36, no 5 (11 janvier 2018) : 1279–94. http://dx.doi.org/10.1177/0144598717751180.
Texte intégralRésumé :
Fracture-hosted methane hydrate deposits exist at many sites worldwide. The growth behavior of CH4 hydrate in fractured media was simulated by TOUGH + HYDRATE (T + H) code. The effects of fracture size, initial condition, and salinity on the growth behavior of hydrate in fractures were investigated. In general, the hydrate layer grew from the two ends and gradually covered on the surface of the fracture. With the formation of hydrate in fractures, the temperature increased sharply since the hydrate acted as a thermal insulation layer. In longer fractures, fast growth of hydrate at the ends of the fracture led to the formation of hydrate plugs with high saturation (called as stopper). In narrower fractures, hydrate dissociation occurred in the middle of the fracture during hydrate growing in the whole fracture due to the cutoff of gas supply by the stopper at the ends. At a low initial subcooling, hydrate formed both on the surface and in the micropores of the media, which was different from that at higher subcooling. In salt solution, the formation of hydrate stopper was inhibited by the salt-removing effect of hydrate formation and the growth of hydrate was more sustainable.
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Bu, Qingtao, Tongju Xing, Gaowei Hu, Changling Liu, Chengfeng Li, Jinhuan Zhao, Zihao Wang, Wengao Zhao et Jiale Kang. « Methane Flux Effect on Hydrate Formation and Its Acoustic Responses in Natural Sands ». Geofluids 2022 (30 mai 2022) : 1–12. http://dx.doi.org/10.1155/2022/7746386.
Texte intégralRésumé :
The acoustic properties of hydrate deposits are important parameters for hydrate geophysical exploration, and the gas leakage model plays a very important role in hydrate accumulation systems. In order to reflect the gas supply environment during hydrate formation, a high-pressure device with a simulated leakage system was designed to achieve different methane flux supplies. The effects of different methane fluxes on the hydrate formation rate and the maximum hydrate saturation were obtained. The results in this study indicate that similar hydrate formation rates occur in systems with different methane fluxes. However, when the methane flux is large, it takes longer to reach the maximum hydrate saturation, and the larger the methane flux, the larger the hydrate saturation formed. In each methane flux system, the elastic velocity increased slowly with increasing hydrate saturation at the beginning of hydrate formation, but velocity increased quickly when the hydrate saturation reached 50–60%. In order to take into account the effect of the gas, the calculated values of the elastic velocity model were compared with the experimental data, which indicated that the BGTL theory and the EMT model are more adaptable and can be used to deduce hydrate morphology. In the large methane flux system, the hydrate mainly forms at grain contacts when the hydrate saturation is 10–60%. As the hydrate saturation reaches 60–70%, hydrate forms first in the pore fluid, and then the hydrates contact sediment particles.
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Bu, Qingtao, Tongju Xing, Chengfeng Li, Jinhuan Zhao, Changling Liu, Zihao Wang, Wengao Zhao, Jiale Kang, Qingguo Meng et Gaowei Hu. « Effect of Hydrate Microscopic Distribution on Acoustic Characteristics during Hydrate Dissociation : An Insight from Combined Acoustic-CT Detection Study ». Journal of Marine Science and Engineering 10, no 8 (9 août 2022) : 1089. http://dx.doi.org/10.3390/jmse10081089.
Texte intégralRésumé :
Geophysical detection techniques are important methods in marine gas hydrate exploration and monitoring, because the small-scale distribution of hydrates has a large impact on the wave velocity. The acoustic response characteristics of hydrate micro-distributions have strong significance for monitoring the hydrate dissociation process. In this paper, experiments simulating the hydrate dissociation process were carried out in a self-developed experimental device combining X-ray computed tomography (X-CT) scanning and ultrasonic detection, which allowed the acoustic wave characteristics and X-CT scanning results to be simultaneously obtained during the hydrate dissociation process. This study found that the hydrate dissociation stage is divided into three stages. The hydrate begins to dissociate at spots where it comes into touch with sand particles early in the dissociation process. The main factor affecting the acoustic wave velocity of hydrates in this stage is changes in the microscopic distribution of hydrate. In the middle stage, a large amount of hydrate decomposes, and the main factor affecting the acoustic wave velocity of hydrate in this stage is the change in hydrate content. In the later stage of hydrate dissociation, the hydrate distribution pattern consists mainly of the pore-filling type, and the hydrate micro-distribution at this stage is the main factor affecting the acoustic wave velocity. This study will be of great significance for understanding the microscopic control mechanism of hydrate reservoir geophysical exploration.
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Sahoo, Sourav K., Laurence J. North, Hector Marín-Moreno, Tim A. Minshull et Angus I. Best. « Laboratory observations of frequency-dependent ultrasonic P-wave velocity and attenuation during methane hydrate formation in Berea sandstone ». Geophysical Journal International 219, no 1 (17 juillet 2019) : 713–23. http://dx.doi.org/10.1093/gji/ggz311.
Texte intégralRésumé :
SUMMARY Knowledge of the effect of methane hydrate saturation and morphology on elastic wave attenuation could help reduce ambiguity in seafloor hydrate content estimates. These are needed for seafloor resource and geohazard assessment, as well as to improve predictions of greenhouse gas fluxes into the water column. At low hydrate saturations, measuring attenuation can be particularly useful as the seismic velocity of hydrate-bearing sediments is relatively insensitive to hydrate content. Here, we present laboratory ultrasonic (448–782 kHz) measurements of P-wave velocity and attenuation for successive cycles of methane hydrate formation (maximum hydrate saturation of 26 per cent) in Berea sandstone. We observed systematic and repeatable changes in the velocity and attenuation frequency spectra with hydrate saturation. Attenuation generally increases with hydrate saturation, and with measurement frequency at hydrate saturations below 6 per cent. For hydrate saturations greater than 6 per cent, attenuation decreases with frequency. The results support earlier experimental observations of frequency-dependent attenuation peaks at specific hydrate saturations. We used an effective medium rock-physics model which considers attenuation from gas bubble resonance, inertial fluid flow and squirt flow from both fluid inclusions in hydrate and different aspect ratio pores created during hydrate formation. Using this model, we linked the measured attenuation spectral changes to a decrease in coexisting methane gas bubble radius, and creation of different aspect ratio pores during hydrate formation.
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Kvamme, Bjørn, Richard B. Coffin, Jinzhou Zhao, Na Wei, Shouwei Zhou, Qingping Li, Navid Saeidi et al. « Stages in the Dynamics of Hydrate Formation and Consequences for Design of Experiments for Hydrate Formation in Sediments ». Energies 12, no 17 (3 septembre 2019) : 3399. http://dx.doi.org/10.3390/en12173399.
Texte intégralRésumé :
Natural gas hydrates in sediments can never reach thermodynamic equilibrium. Every section of any hydrate-filled reservoir is unique and resides in a stationary balance that depends on many factors. Fluxes of hydrocarbons from below support formation of new hydrate, and inflow of water through fracture systems leads to hydrate dissociation. Mineral/fluid/hydrate interaction and geochemistry are some of the many other factors that determine local hydrate saturation in the pores. Even when using real sediments from coring it is impossible to reproduce in the laboratory a natural gas hydrate reservoir which has developed over geological time-scales. In this work we discuss the various stages of hydrate formation, with a focus on dynamic rate limiting processes which can lead to trapped pockets of gas and trapped liquid water inside hydrate. Heterogeneous hydrate nucleation on the interface between liquid water and the phase containing the hydrate former rapidly leads to mass transport limiting films of hydrate. These hydrate films can delay the onset of massive, and visible, hydrate growth by several hours. Heat transport in systems of liquid water and hydrate is orders of magnitude faster than mass transport. We demonstrate that a simple mass transport model is able to predict induction times for selective available experimental data for CO2 hydrate formation and CH4 hydrate formation. Another route to hydrate nucleation is towards mineral surfaces. CH4 cannot adsorb directly but can get trapped in water structures as a secondary adsorption. H2S has a significant dipole moment and can adsorb directly on mineral surfaces. The quadropole-moment in CO2 also plays a significant role in adsorption on minerals. Hydrate that nucleates toward minerals cannot stick to the mineral surfaces so the role of these nucleation sites is to produce hydrate cores for further growth elsewhere in the system. Various ways to overcome these obstacles and create realistic hydrate saturation in laboratory sediment are also discussed.
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GHAFIYEHSANJ, Elham, Kamaladdin DILMAGHANI, Nader CHAPARZADE et Sara SAADATMAND. « COMPARATIVE STUDY ON ANTIOXIDANT ACTIVITY OF SALVIA NEMOROSA L. FROM TWO DIFFERENT LOCATIONS ». SOUTHERN BRAZILIAN JOURNAL OF CHEMISTRY 28, no 28 (20 juin 2020) : 17–21. http://dx.doi.org/10.48141/sbjchem.v28.n28.2020.03_ghafiyehsanj_pgs_17_21.pdf.
Texte intégralRésumé :
In order to investigate the antioxidant activity of Salvia nemorosa L. collected from Ahar and Urmia regions in Iran at different growth stages, aerial parts of sage after collecting were dried, and for measurement, the ability of scavenge DPPH (2,2-diphenyl-1-picryl-hydrazyl-hydrate) radical in different concentrations (0.025, 0.05, 0.07, 0.1, 0.2, 0.04 and 0.6) of methanolic extracts were prepared. The result showed that the ability to scavenge DPPH radical and amount of inhibition percent of vegetative stage leaves, flowering stage leaves, and flowers increased with increasing concentrations of methanolic extracts from 0.25 to 0.6 mg/mL. In the region of Urmia, the highest amount of DPPH inhibition there was in vegetative stage leaves, and the lowest amount of DPPH inhibition was seen in flowers. In Ahar regions, unlike the Urmia region, the highest amount of DPPH inhibition there was in flowers, but the lowest of DPPH inhibition was seen in flowering stage leaves. Also, the content of inhibition of DPPH in Ahar and Urmia regions similarly increased between two phenological stages (vegetative stage leaves, flowering stage leaves, and flowers) in 0.4 mg/mL and 0.6 mg/mL concentrations.
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Li, Jingjing, Renkai Li, Xiaoping Wu, Ruby Lai-Chong Hoo, Simon Ming-Yuen Lee, Timothy Man-Yau Cheung, Bryan Siu-Yin Ho et George Pak-Heng Leung. « Amauroderma rugosum Protects PC12 Cells against 6-OHDA-Induced Neurotoxicity through Antioxidant and Antiapoptotic Effects ». Oxidative Medicine and Cellular Longevity 2021 (3 février 2021) : 1–15. http://dx.doi.org/10.1155/2021/6683270.
Texte intégralRésumé :
Amauroderma rugosum (AR) is a dietary mushroom in the Ganodermataceae family whose pharmacological activity and medicinal value have rarely been reported. In this study, the antioxidant capacity and neuroprotective effects of AR were investigated. The aqueous extract of AR was confirmed to contain phenolic compounds, polysaccharides, and triterpenes. The results of 2,2-diphenyl-1-picryl-hydrazyl-hydrate (DPPH) and total antioxidant capacity assays revealed that AR extract scavenged reactive oxygen species. Moreover, AR extract decreased the cytotoxicity, oxidative stress, mitochondrial dysfunction, and apoptosis of PC12 cells induced by 6-hydroxydopamine (6-OHDA). In addition, 6-OHDA upregulated the expressions of proapoptotic proteins and downregulated the Akt (protein kinase B)/mTOR- (mammalian target of rapamycin-) and MEK (mitogen-activated protein kinase kinase)/ERK- (extracellular signal-regulated kinases-) dependent signaling pathways. These effects of 6-OHDA were abolished or partially reversed by AR extract. Furthermore, the neuroprotective effects of AR in 6-OHDA-treated PC12 cells were significantly abolished by Akt and MEK inhibitor. Thus, AR extract possesses neuroprotective effects, probably through its antioxidant and antiapoptotic effects. These findings suggest the potential application of AR in the prevention or treatment of oxidative stress-related neurodegenerative diseases such as Parkinson’s disease.
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Ghafiyehsanj, Elham, Kamaladdin Dilmaghani, Nader Chaparzade et Sara Saadatmand. « Comparative Study on Antioxidant Activity of Salvia Nemorosa L. From Two Different Locations ». Southern Brazilian Journal of Chemistry 28, no 28 (20 juin 2020) : 17–21. http://dx.doi.org/10.37633/sbjc.28(28)2020.17-21.
Texte intégralRésumé :
In order to investigate the antioxidant activity of Salvia nemorosa L. collected from Ahar and Urmia regions in Iran at different growth stages, aerial parts of sage after collecting were dried, and for measurement, the ability of scavenge DPPH (2,2-diphenyl-1-picryl-hydrazyl-hydrate) radical in different concentrations (0.025, 0.05, 0.07, 0.1, 0.2, 0.04 and 0.6) of methanolic extracts were prepared. The result showed that the ability to scavenge DPPH radical and amount of inhibition percent of vegetative stage leaves, flowering stage leaves, and flowers increased with increasing concentrations of methanolic extracts from 0.25 to 0.6 mg/ml. In the region of Urmia, the highest amount of DPPH inhibition there was in vegetative stage leaves, and the lowest amount of DPPH inhibition was seen in flowers. In Ahar regions, unlike the Urmia region, the highest amount of DPPH inhibition there was in flowers, but the lowest of DPPH inhibition was seen in flowering stage leaves. Also, the content of inhibition of DPPH in Ahar and Urmia regions similarly increased between two phenological stages (vegetative stage leaves, flowering stage leaves, and flowers) in 0.4 mg/ml and 0.6 mg/ml concentrations
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Thalib, Abdul, Rina Masadah, Prihartono Prihartono, Firdaus Hamid, Muhammad Haidir, Hulan Hasan, Sudin Keliwawa et Irman Labulawa. « Antioxidant Activity of Laportea decumana (Roxb) Wedd Ethanol and n-Hexane Extracts ». Open Access Macedonian Journal of Medical Sciences 10, A (14 mars 2022) : 590–94. http://dx.doi.org/10.3889/oamjms.2022.8399.
Texte intégralRésumé :
Background: Laportea decumana (robx.) wedd. is a traditional medicine used by Indonesian people, especially in eastern Indonesia, Maluku Ambon. But its utilization has not been based on evidence-based research, so it still needs to be developed to be used as complementary nursing therapy in the future.
Aim: This study aims to determine the phytochemical content and antioxidant activity of Laportea decumana (robx.) wedd. from Ambon Maluku.
Method: Extraction is done by the maceration method with 96% ethanol solvent. Phytochemical tests are performed with thin-layer chromatography (TLC) to look at flavonoids, tannins and triterpenoids, then alkaloids and saponins using tube tests. The antioxidant activity test was conducted using the 2,2-diphenyl-1-picryl-hydrazyl-hydrate (DPPH) method.
Results: Laportea decumana (robx.) wedd. phytochemical test positively contains alkaloids, flavonoids, tannins, triterpenoids and saponins. The antioxidant activity of Laportea Decumana (Robx) Wedd Ethanol Extract (LDrW-EE) 22.81 ppm, Laportea Decumana (Robx) Wedd n-Hexane Extract (LDrW-NHE) 44.89 ppm and vitamin C 6.03 ppm.
Conclusion: LDrW-EE antioxidant activity is better when compared to LDrW-NHE but no better than vitamin C
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Manivasagam, Deepigaa, Arvind Muthukrishnan et Rajeshkumar S. « Assessment of Immunomodulatory Effect on Natural Antioxidants – An In Vitro Study ». Journal of Evolution of Medical and Dental Sciences 10, no 42 (18 octobre 2021) : 3612–16. http://dx.doi.org/10.14260/jemds/2021/733.
Texte intégralRésumé :
BACKGROUND Garlic has anti allergic, anti-tumour and chemo preventive effect. Turmeric has analgesic, anti-inflammatory, wound healing, and immunomodulatory activities. Spirulina has antioxidant, immunomodulatory, anti-inflammatory, anticancer, antiviral, and antibacterial effects. Honey has antimicrobial, antioxidant, anticancer, antiinflammatory. The purpose of this study was to prepare herbal formulations of garlic, turmeric, honey, and spirulina and analyse its immunomodulatory effect. METHODS Garlic, turmeric, honey, and spirulina were combined with 100 ml of distilled water and simmered for 15 minutes before being filtered and condensed again to 5 ml. The diphenyl 1-picryl-hydrazyl-hydrate test (DPPH), ferric reducing antioxidant power assay (FRAP) and H2O2 assays were used to evaluate the immunomodulatory effect. RESULTS The prepared extract showed significant results at 50 l when assessed using DPPH, FRAP and H2O2 assay (i.e.) 72.1 %, 94.6 % and 67.9 % respectively. CONCLUSIONS This in-vitro study shows that the combination of garlic, turmeric, honey and spirulina formulation have good immunomodulatory effects when compared to the standard. Hence, in future, it can be used as a safe alternative instead of commercially available medicines in the form of in-situ gel for management of immune mediated disorders. KEY WORDS Garlic, Turmeric, Honey, Spirulina, Antioxidant, Immunomodulator
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Manohar Babu, S., V. Harish, D. Sivanaga Reddy, K. Jowhar Ali et N. Srinavya. « ANTI OXIDANT, MICROBIAL AND PHYTO CHEMICAL STUDIES OF CARICA PAPAYA MILK : A NATURAL HAND SANITIZER ». International Journal of Advanced Research 10, no 02 (28 février 2022) : 1062–66. http://dx.doi.org/10.21474/ijar01/14313.
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In this study, the effect of Carica papayaagainst various microorganisms is evaluated using DPPH (2,2-diphenyl-1-picryl-hydrazyl-hydrate) assay for antioxidant activity. The focus is on employing the antimicrobial and antioxidant activities of papaya milk as a natural antimicrobial by preparing hand sanitizer.Papaya (Carica papaya Linn), a nutraceutical fruit well known for its nutritional values and potent medicinal properties such as antioxidant, anti-bacterial, anti-helminthic, anti-fungal, anti-hypertensive and anti-fertility, free radical scavenging activity [1-10]. The study includesextraction of C.papaya milk from C. papaya fruit and identification of phytochemical constituents by performing chemical tests. Preparation of sanitizer with 5ml and 7ml of C. Papaya Milk for 10 ml sanitizer.Evaluation of antimicrobial activity of prepared sanitizer on cultures from hand using spread plate method.Determination of sanitizing ability was done by calculating percent reduction in colony forming units (CFU) before and after sanitization. Evaluation of antioxidant activity by in vitro DPPH Scavenging method.The standard sanitizer had shown 75% effectiveness, isopropyl alcohol shows90% effectiveness, and finally sanitizer which is prepared from papaya milk was found to be 58% effective against micro-organisms.
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Xu, Ziyue, Peizhong Gao, Dun Liu, Wenzhi Song, Lingfan Zhu et Xu Liu. « Chemical Composition and In Vitro Antioxidant Activity of Sida rhombifolia L. Volatile Organic Compounds ». Molecules 27, no 20 (19 octobre 2022) : 7067. http://dx.doi.org/10.3390/molecules27207067.
Texte intégralRésumé :
In the current study, the phytochemical constituents of volatile organic compounds (VOCs) obtained from Sida rhombifolia L. were identified by GC-FID and GC-MS analysis. A total of 73 volatile organic compounds were identified. The major components of S. rhombifolia VOCs were identified as palmitic acid (21.56%), phytol (7.02%), 6,10,14-trimethyl-2-pentadecanone (6.30%), oleic acid (5.48%), 2-pentyl-furan (5.23%), and linoleic acid (3.21%). The VOCs are rich in fatty acids (32.50%), olefine aldehyde (9.59%), ketone (9.41%), enol (9.02%), aldehyde (8.63%), and ketene (6.41%). The antioxidant capacity of S. rhombifolia VOCs was determined by 2,2-diphenyl-1-picryl-hydrazyl-hydrate (DPPH), 2,2-azinobis-(3-ethylbenzothiazolin-6-sulfonic acid) diammonium salt (ABTS), and ferric reducing/antioxidant power (FRAP) methods with butylated hydroxytoluene (BHT) and Trolox as standard. The VOCs showed dose-dependent antioxidant activity with IC50 (50% inhibitory concentration) values of 5.48 ± 0.024 and 1.47 ± 0.012 mg/mL for DPPH and ABTS assays, respectively. FRAP antioxidant capacity was 83.10 ± 1.66 mM/g. The results show that the VOCs distilled from S. rhombifolia have a moderate antioxidant property that can be utilized as a natural botanical supplement or an antioxidant.
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Garcia, Eugenio José, Tatiane Luiza Cadorin Oldoni, Severino Matias de Alencar, Alessandra Reis, Alessandro D. Loguercio et Rosa Helena Miranda Grande. « Antioxidant activity by DPPH assay of potential solutions to be applied on bleached teeth ». Brazilian Dental Journal 23, no 1 (2012) : 22–27. http://dx.doi.org/10.1590/s0103-64402012000100004.
Texte intégralRésumé :
The aim of this study was to assess, using the DPPH assay, the antioxidant activity of several substances that could be proposed to immediately revert the problems caused by bleaching procedures. The percentage of antioxidant activity (AA%) of 10% ascorbic acid solution (AAcidS), 10% ascorbic acid gel (AAcidG), 10% sodium ascorbate solution (SodAsS), 10% sodium ascorbate gel (SodAsG), 10% sodium bicarbonate (Bicarb), Neutralize® (NE), Desensibilize® (DES), catalase C-40 at 10 mg/mL (CAT), 10% alcohol solution of alpha-tocopherol (VitE), Listerine® (LIS), 0.12% chlorhexidine (CHX), Croton Lechleri (CL), 10 % aqueous solution of Uncaria Tomentosa (UT), artificial saliva (ArtS) and 0.05% sodium fluoride (NaF) was assessed in triplicate by 2,2-diphenyl-1-picryl-hydrazyl-hydrate (DPPH) free radical assay. All substances exhibited antioxidant activity, except for CL. AAcidS, AAcidG and VitE exhibited the highest AA% (p<0.05). On the contrary, CHX, NE, LIS and NaF showed the lowest AA% (p<0.05). In conclusion, AAcidS, AAcidG, SodAsS, SodAsG and VitE presented the highest antioxidant activity among substances tested in this study. The DPPH assay provides an easy and rapid way to evaluate potential antioxidants.
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Pollett, Jim. « Hydrant Helper Extracts Hydrant Seats ». Opflow 47, no 9 (novembre 2021) : 30. http://dx.doi.org/10.1002/opfl.1607.
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Zhang, Zijian, De-hua Han et Daniel R. McConnell. « Characterization of elastic properties of near-surface and subsurface deepwater hydrate-bearing sediments ». GEOPHYSICS 78, no 3 (1 mai 2013) : D169—D179. http://dx.doi.org/10.1190/geo2012-0385.1.
Texte intégralRésumé :
Hydrate-bearing sands and shallow nodular hydrate are potential energy resources and geohazards, and they both need to be better understood and identified. Therefore, it is useful to develop methodologies for modeling and simulating elastic constants of these hydrate-bearing sediments. A gas-hydrate rock-physics model based on the effective medium theory was successfully applied to dry rock, water-saturated rock, and hydrate-bearing rock. The model was used to investigate the seismic interpretation capability of hydrate-bearing sediments in the Gulf of Mexico by computing elastic constants, also known as seismic attributes, in terms of seismic interpretation, including the normal incident reflectivity (NI), Poisson’s ratio (PR), P-wave velocity ([Formula: see text]), S-wave velocity ([Formula: see text]), and density. The study of the model was concerned with the formation of gas hydrate, and, therefore, hydrate-bearing sediments were divided into hydrate-bearing sands, hydrate-bearing sands with free gas in the pore space, and shallow nodular hydrate. Although relations of hydrate saturation versus [Formula: see text] and [Formula: see text] are different between structures I and II gas hydrates, highly concentrated hydrate-bearing sands may be interpreted on poststack seismic amplitude sections because of the high NI present. The computations of elastic constant implied that hydrate-bearing sands with free gas could be detected with the crossplot of NI and PR from prestack amplitude analysis, and density may be a good hydrate indicator for shallow nodular hydrate, if it can be accurately estimated by seismic methods.
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Kvamme, Bjørn, Jinzhou Zhao, Na Wei et Navid Saeidi. « Hydrate—A Mysterious Phase or Just Misunderstood ? » Energies 13, no 4 (17 février 2020) : 880. http://dx.doi.org/10.3390/en13040880.
Texte intégralRésumé :
Hydrates that form during transport of hydrocarbons containing free water, or water dissolved in hydrocarbons, are generally not in thermodynamic equilibrium and depend on the concentration of all components in all phases. Temperature and pressure are normally the only variables used in hydrate analysis, even though hydrates will dissolve by contact with pure water and water which is under saturated with hydrate formers. Mineral surfaces (for example rust) play dual roles as hydrate inhibitors and hydrate nucleation sites. What appears to be mysterious, and often random, is actually the effects of hydrate non-equilibrium and competing hydrate formation and dissociation phase transitions. There is a need to move forward towards a more complete non-equilibrium way to approach hydrates in industrial settings. Similar challenges are related to natural gas hydrates in sediments. Hydrates dissociates worldwide due to seawater that leaks into hydrate filled sediments. Many of the global resources of methane hydrate reside in a stationary situation of hydrate dissociation from incoming water and formation of new hydrate from incoming hydrate formers from below. Understanding the dynamic situation of a real hydrate reservoir is critical for understanding the distribution characteristics of hydrates in the sediments. This knowledge is also critical for designing efficient hydrate production strategies. In order to facilitate the needed analysis we propose the use of residual thermodynamics for all phases, including all hydrate phases, so as to be able to analyze real stability limits and needed heat supply for hydrate production.
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Fu, Weiqi, Zhiyuan Wang, Baojiang Sun, Jianchun Xu, Litao Chen et Xuerui Wang. « Rheological Properties of Methane Hydrate Slurry in the Presence of Xanthan Gum ». SPE Journal 25, no 05 (3 février 2020) : 2341–52. http://dx.doi.org/10.2118/199903-pa.
Texte intégralRésumé :
Summary Methane hydrate formation in a xanthan-gum (XG) solution is an important problem for drilling in a deepwater environment. It not only alters the rheology of the drilling fluid in the wellbore but increases the risks of a hydrate blockage in the blowout preventer. The current work is performing groups of experiments to investigate the rheology of the hydrate slurry under XG concentrations of 0.15, 0.2, 0.25, and 0.3%, shear rates from 10 to 480 s−1, and hydrate concentrations from 1.01 to 9.12%. The experimental results show that the hydrate slurry with XG additives exhibits an obvious shear-thinning behavior, which is because the XG solution has strong pseudoplastic characteristics, and the inner structures of the flocculated hydrate particles suspended in the hydrate slurry are broken up during the hydrate-slurry flow. The increase of hydrate concentrations in the hydrate slurry can reduce the non-Newtonian fluid index and make the rheology of the hydrate slurry become more shear-thinning. However, as the XG concentration increases in the hydrate slurry, the influence of the hydrate concentration on the rheology of the hydrate slurry gradually weakens. Empirical Herschel–Bulkley-type equations are developed to describe the rheology of the hydrate slurry with XG for the current experimental condition, considering the shear rate, hydrate concentration, and XG concentration. In the proposed equations, the non-Newtonian factor and the consistency factor are expressed as functions of XG concentration empirically. Correction Notice:The preprint version of this paper was modified from its original version to correct Figs. 8 and 9 and Eqs. 6 through 9 on page 7. Errata explaining the corrections are included below as Supporting Information.
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Zhang, Jianbo, Zhiyuan Wang, Shengnan Chen, Jihao Pei, Nan Ma, Shikun Tong, Wenqiang Lou et Baojiang Sun. « Experimental Study and Prediction Model for Hydrate Plugging Formation in Single-Pass Gas-Dominated Pipes with Diameter Reduction ». SPE Journal 27, no 02 (15 décembre 2021) : 1244–62. http://dx.doi.org/10.2118/209189-pa.
Texte intégralRésumé :
Summary Gas hydrate plugging in flowlines acts as a major blockage risk in oil, gas, and natural gas hydrate production. Current studies on hydrate plugging is mainly conducted in pipes with a constant diameter, whereas the effects of varying diameters have been less explored. Pipes with diameter reductions are very common in the oil and gas production process. Herein, by performing experiments with pipes of four different sizes, including one with a constant diameter and three with diameter reductions, the hydrate plugging in single-pass gas-dominated pipes with diameter reduction is investigated systematically, the results of which show that the existence of diameter reduction can facilitate the deposition of hydrate particles on pipe walls and the formation of a hydrate deposition layer. Meanwhile, hydrate sloughing occurs during the growth of the hydrate deposition layer under fluid shear force. With the increase in the diameter reduction ratio or subcooling for hydrate formation, the hydrate deposition is observed to increase significantly, thus resulting in the reduction of time for hydrate plugging. According to these results, the hydrate plugging mechanism in pipes with diameter reduction is proposed. Further, in combination with the hydrate deposition difference between the inside and outside of the arc-shaped low-speed area, a new numerical model is established for hydrate plugging prediction in the pipe with diameter reduction, which can predict the growth and evolution of the hydrate deposition layer accurately with the consideration of the diameter’s reduction. The results of this work provide a valuable guidance for the targeted prevention and management of hydrate plugging in flowlines with diameter reductions.
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Zhang, Zijian, De-hua Han et Qiuliang Yao. « Quantitative interpretation for gas hydrate accumulation in the eastern Green Canyon Area, Gulf of Mexico using seismic inversion and rock physics transform ». GEOPHYSICS 76, no 4 (juillet 2011) : B139—B150. http://dx.doi.org/10.1190/1.3581358.
Texte intégralRésumé :
Gas hydrate can be interpreted from seismic data through observation of bottom simulating reflector (BSR). It is a challenge to interpret gas hydrate without BSR. Three-dimensional qualitative and quantitative seismic interpretations were used to characterize gas hydrate distribution and concentration in the eastern Green Canyon area of the Gulf of Mexico, where BSR is absent. The combination of qualitative and quantitative interpretation reduces ambiguities in the estimation and identification of gas hydrate. Sandy deposition and faults are qualitatively interpreted from amplitude data. The 3D acoustic impedance volume was interpreted in terms of high P-impedance hydrate zones and low P-impedance free gas zones. Gas hydrate saturation derived from P-impedance is estimated by a rock physics transform. We interpreted gas hydrate in the sand-prone sediments with a maximum saturation of approximately 50% of the pore space. Sheet-like and some bright spot gas hydrate accumulations are interpreted. The interpretation of sheet-like gas hydrate within sand-prone sediments around faults suggests that fluid moves into the sand zones laterally by conduits. Variations in depths of interpreted gas hydrate zones imply nonequilibrium conditions. Low P-impedance free gas zones within high P-impedance gas hydrate zones imply possible coexistence of hydrate and free gas within the hydrate stability zone. We propose that gas hydrate distribution and concentration are associated with structures, buried sedimentary bodies, sources of gas, and fluid flux.
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Kumano, Hiroyuki, Tatsunori Asaoka, Tatsuya Hayashi et Peng Zhang. « Measurement of Latent Heat of Tetra-n-Butyl Ammonium Bromide Hydrate and Specific Enthalpy of Its Slurry ». International Journal of Air-Conditioning and Refrigeration 23, no 03 (septembre 2015) : 1550025. http://dx.doi.org/10.1142/s201013251550025x.
Texte intégralRésumé :
The specific heat of a tetra-n-butyl ammonium bromide (TBAB) aqueous solution, the latent heat of a TBAB hydrate, and the specific enthalpy of a TBAB hydrate slurry were measured to understand the thermal storage characteristics of TBAB hydrate slurry. A solution sample and the hydrate slurry were heated, the change in temperature was measured, and the specific heat of the TBAB aqueous solution and the specific enthalpy of the hydrate slurry were obtained from the change in temperature. Two types of TBAB hydrate form. Therefore, the hydrates were separated from the hydrate slurry formed from TBAB aqueous solution having several initial concentrations. The hydrate crystals were placed into solution, and the latent heats were obtained from the temperature change of the solution. The specific enthalpy of the hydrate slurry was estimated from the latent heats of the hydrate crystals and the specific heat of the solution under phase equilibrium conditions, and the measured and estimated values were compared.
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Aromada, Solomon Aforkoghene, Bjørn Kvamme, Na Wei et Navid Saeidi. « Enthalpies of Hydrate Formation and Dissociation from Residual Thermodynamics ». Energies 12, no 24 (11 décembre 2019) : 4726. http://dx.doi.org/10.3390/en12244726.
Texte intégralRésumé :
We have proposed a consistent thermodynamic scheme for evaluation of enthalpy changes of hydrate phase transitions based on residual thermodynamics. This entails obtaining every hydrate property such as gas hydrate pressure-temperature equilibrium curves, change in free energy which is the thermodynamic driving force in kinetic theories, and of course, enthalpy changes of hydrate dissociation and formation. Enthalpy change of a hydrate phase transition is a vital property of gas hydrate. However, experimental data in literature lacks vital information required for proper understanding and interpretation, and indirect methods of obtaining this important hydrate property based on the Clapeyron and Clausius-Clapeyron equations also have some limitations. The Clausius-Clapeyron approach for example involves oversimplifications that make results obtained from it to be inconsistent and unreliable. We have used our proposed approach to evaluate consistent enthalpy changes of hydrate phase transitions as a function of temperature and pressure, and hydration number for CH4 and CO2. Several results in the literature of enthalpy changes of hydrate dissociation and formation from experiment, and Clapeyron and Clausius-Clapeyron approaches have been studied which show a considerable disagreement. We also present the implication of these enthalpy changes of hydrate phase transitions to environmentally friendly production of energy from naturally existing CH4 hydrate and simultaneously storing CO2 on a long-term basis as CO2 hydrate. We estimated enthalpy changes of hydrate phase transition for CO2 to be 10–11 kJ/mol of guest molecule greater than that of CH4 within a temperature range of 273–280 K. Therefore, the exothermic heat liberated when a CO2 hydrate is formed is greater or more than the endothermic heat needed for dissociation of the in-situ methane hydrate.
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Sun, Qiang, Mei Du, Xingxun Li, Xuqiang Guo et Lanying Yang. « Morphology Investigation on Cyclopentane Hydrate Formation/Dissociation in a Sub-Millimeter-Sized Capillary ». Crystals 9, no 6 (14 juin 2019) : 307. http://dx.doi.org/10.3390/cryst9060307.
Texte intégralRésumé :
The formation, dissociation, and reformation of cyclopentane (CP) hydrate in a sub-millimeter-sized capillary were conducted in this work, and the morphology of CP hydrate was obtained during above processes, respectively. The influences of the supercooling degree, i.e., the hydrate formation driving force, on CP hydrate crystals’ aspect and growth rate were also investigated. The results demonstrate that CP forms hydrate with the water melting from ice at the interface between the CP and melting water at a temperature slightly above 273.15 K. With the action of hydrate memory effect, the CP hydrate in the capillary starts forming at the CP-water interface or CP–water–capillary three-phase junction and grows around the CP–water interface. The appearance and growth rate of CP hydrate are greatly influenced by the supercooling degree. It indicates that CP hydrate has a high aggregation degree and good regularity at a high supercooling degree (or a low formation temperature). The growth rate of CP hydrate crystals greatly increases with the supercooling degree. Consequently, the temperature has a significant influence on the formation of CP hydrate in the capillary. That means the features of CP hydrate crystals in a quiescent system could be determined and controlled by the temperature setting.
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Lee, Myung W., et Timothy S. Collett. « Elastic properties of gas hydrate‐bearing sediments ». GEOPHYSICS 66, no 3 (mai 2001) : 763–71. http://dx.doi.org/10.1190/1.1444966.
Texte intégralRésumé :
Downhole‐measured compressional- and shear‐wave velocities acquired in the Mallik 2L-38 gas hydrate research well, northwestern Canada, reveal that the dominant effect of gas hydrate on the elastic properties of gas hydrate‐bearing sediments is as a pore‐filling constituent. As opposed to high elastic velocities predicted from a cementation theory, whereby a small amount of gas hydrate in the pore space significantly increases the elastic velocities, the velocity increase from gas hydrate saturation in the sediment pore space is small. Both the effective medium theory and a weighted equation predict a slight increase of velocities from gas hydrate concentration, similar to the field‐observed velocities; however, the weighted equation more accurately describes the compressional- and shear‐wave velocities of gas hydrate‐bearing sediments. A decrease of Poisson’s ratio with an increase in the gas hydrate concentration is similar to a decrease of Poisson’s ratio with a decrease in the sediment porosity. Poisson’s ratios greater than 0.33 for gas hydrate‐bearing sediments imply the unconsolidated nature of gas hydrate‐bearing sediments at this well site. The seismic characteristics of gas hydrate‐bearing sediments at this site can be used to compare and evaluate other gas hydrate‐bearing sediments in the Arctic.
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Yarakhmedov, M. B., A. G. Kiiamov, M. E. Semenov, A. P. Semenov et A. S. Stoporev. « Peculiarities of Decomposition of Gas Hydrates in the Presence of Methanol at Atmospheric Pressure ». Chemistry and Technology of Fuels and Oils 634, no 6 (2022) : 40–43. http://dx.doi.org/10.32935/0023-1169-2022-634-6-40-43.
Texte intégralRésumé :
The study of the decomposition process of gas hydrates at atmospheric pressure and temperatures below 0°C revealed that methanol could affect this process in different ways, depending on its saturation with environmental components. Indeed, dueto the absorption of methane from the hydrate by methanol, the onset of its decomposition is observed at lower temperatures.Nevertheless, decomposition proceeds more slowly than with pure methane hydrate. When the methanol surrounding the methane hydrate is saturated with other medium components, the hydrate dissociation occurs at the equilibrium temperature (when intersecting the hydrate-ice-gas curve in a system without additives) regardless of the alcohol concentration. A similar situation is observed with hydrate obtained from a methane-propane gas mixture; however, under experimental conditions, ice beginsto melt at a lower temperature compared to the dissociation point of methane-propane hydrate (in the case of methane hydrate, the situation is reversed: the hydrate is less stable). High concentrations of methanol (above 40 mass%) lead to a significant decrease in the temperature of hydrate decomposition. The data obtained show that methanol in low dosages (about 10 mass%) can be usedfor gas storage and transportation since, under certain conditions, it does not shift the equilibrium curve of hydrate formation and slows down the process of methane hydrate decomposition.
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Zeng, Haopeng, Yu Zhang, Lei Zhang, Zhaoyang Chen et Xiaosen Li. « Study on Hydrate Production Behaviors by Depressurization Combined with Brine Injection in the Excess-Water Hydrate Reservoir ». Entropy 24, no 6 (29 mai 2022) : 765. http://dx.doi.org/10.3390/e24060765.
Texte intégralRésumé :
Depressurization combined with brine injection is a potential method for field production of natural gas hydrate, which can significantly improve production efficiency and avoid secondary formation of hydrate. In this work, the experiments of hydrate production using depressurization combined with brine injection from a simulated excess-water hydrate reservoir were performed, and the effects of NaCl concentration on hydrate decomposition, temperature change, and heat transfer in the reservoir were investigated. The experimental results indicate that there is little gas production during depressurization in a excess-water hydrate reservoir, and the gas dissociated from hydrate is trapped in pores of sediments. The high-water production reduces the final gas recovery, which is lower than 70% in the experiments. The increasing NaCl concentration only effectively promotes gas production rate in the early stage. The final cumulative gas production and average gas production rate have little difference in different experiments. The NaCl concentration of the produced water is significantly higher than that which is in contact with hydrate in the sediments because the water produced by hydrate decomposition exists on the surface of undissociated hydrate. The high concentration of NaCl in the produced water from the reactor significantly reduces the promoting effect and efficiency of NaCl solution on hydrate decomposition. The injection of NaCl solution decreases the lowest temperature in sediments during hydrate production, and increases the sensible heat and heat transfer from environment for hydrate decomposition. The changes of temperature and resistance effectively reflect the distribution of the injected NaCl solution in the hydrate reservoir.
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Chen, Qiang, Nengyou Wu, Changling Liu, Changchun Zou, Yang Liu, Jianye Sun, Yanlong Li et Gaowei Hu. « Research Progress on Global Marine Gas Hydrate Resistivity Logging and Electrical Property Experiments ». Journal of Marine Science and Engineering 10, no 5 (9 mai 2022) : 645. http://dx.doi.org/10.3390/jmse10050645.
Texte intégralRésumé :
Natural gas hydrate is widely spread in marine environments around the world. It has great energy potential due to its high methane gas content. High-precision exploration and evaluation of marine gas hydrate still face great challenges as it is affected by the complex reservoir control mechanisms and distribution characteristics. Resistivity is widely used in geophysical logging and theoretical research on gas hydrate-bearing reservoirs by utilizing the high sensitivity electrical response. In this paper, based on the examination of the global marine gas hydrate occurrences, resistivity logging results are summarized. Then the key remaining gas hydrate resistivity experimental concerns are reviewed. In summary, resistivity properties are a reliable means to derive the gas hydrate reservoir characteristics, despite the effect induced by the anisotropic properties of hydrate reservoirs and drilling technology. The overall resistivity change associated with the occurrence of pore filling gas hydrate in reservoirs are relatively small, and the specific value is affected by sediment lithology and hydrate saturation. On the other hand, fracture filling hydrate reservoirs have strong anisotropy, and massive hydrate occurrences (i.e., layers of gas hydrate with no sediment) section shows very high resistivity variation. Clay minerals are an important factor restricting the accurate estimation of gas hydrate saturations from in situ resistivity measurements. Many experimental studies have proposed the correction of Archie empirical formula, but widely representative models have not yet been developed. It is worth noting that more complex resistivity measurements may be able to provide additional electrical response information on various gas hydrate systems.