Статті в журналах: "³¹P nuclear magnetic resonance (NMR) spectroscopy"

1

Parlak, Yeliz, and Nuray Güzeler. "Nuclear Magnetic Resonance Spectroscopy Applications In Foods." Current Research in Nutrition and Food Science Journal 4, Special-Issue-October (October 8, 2016): 161–68. http://dx.doi.org/10.12944/crnfsj.4.special-issue-october.22.

Повний текст джерела

Анотація:

Nuclear magnetic resonance spectroscopy (NMR) is the most powerful technique for determining the structure of organic compounds. NMR techniques are used successfully in various food systems for quality control and research. NMR spectroscopy is used to determine structure of proteins, aminoacid profile, carotenoids, organic acids, lipid fractions, the mobility of the water in foods. NMR spectroscopy is also used to identify and quantify the metabolites in foods. Also vegetable oils, fish oils, fish and meat, milk, cheese, wheat, fruit juices, coffee, green tea, foods such as wine and beer are among the last NMR applications. In addition, NMR spectroscopy is utilized for foodomics which is a new discipline that brings food science and nutritional research together. NMR techniques used for the food authentication are one- and two-dimensional NMR techniques, high resolution liquid state 1H and 13C NMR techniques, N15 and P-31 NMR techniques, 1H HR/MAS (high resolution magic angle spinning) NMR techniques. At this study, usage purposes of nuclear magnetic resonance spectroscopy for foods were collected.

Стилі APA, Harvard, Vancouver, ISO та ін.

2

KARABACAK ATAY, Çiğdem, and Mehmet ULUTÜRK. "Synthesis and Theoretical Calculations of Benzoic Acid-Based New Mono Azo Dye." Süleyman Demirel Üniversitesi Fen Edebiyat Fakültesi Fen Dergisi 17, no. 2 (November 25, 2022): 559–67. http://dx.doi.org/10.29233/sdufeffd.1181119.

Повний текст джерела

Анотація:

This study describes the synthesis, characterization and theoretical calculation of 3,5-dihydroxy-2-(naphthalen-2-yldiazenyl) benzoic acid. The synthesized compound was obtained through efficient synthetic route using 2-Naphthylamine and 3,5-dihydroxybenzoic acid as starting materials and characterized by various spectroscopic techniques such as Fouirer Transform Infrared Spectroscopy (FTIR), Proton Nuclear Magnetic Resonance Spectroscopy (1H-NMR), Carbon Nuclear Magnetic Resonance Spectroscopy (13C-NMR), Ultraviolet–visible spectroscopy (UV-Vis). All theoretical calculation was performed with Density Functional Theory (DFT). Optimized molecular structure, vibrational spectra, NMR chemical shift values, frontier molecular orbitals, bond lengths (Å), bond angles (°) and Molecular Electrostatic Potential (MEP) diagram of molecule were calculated using the 6-311G(d,p) basis set. It has been observed that the results obtained from the experimental and theoretical calculations support each other and were in harmony.

Стилі APA, Harvard, Vancouver, ISO та ін.

3

Attaelmannan, M. A., A. A. Dahl, and R. S. Reid. "Analysis of volatile fatty acids in rumen fluid by proton NMR spectroscopy." Canadian Journal of Animal Science 79, no. 3 (September 1, 1999): 401–4. http://dx.doi.org/10.4141/a99-013.

Повний текст джерела

Анотація:

A study was conducted to quantify the volatile fatty acid (VFA) concentrations in aqueous and rumen fluid samples using a standard additions based quantitative proton nuclear magnetic resonance (NMR) spectroscopic method. Standard plots for acetic, propionic and butyric acids were all found to be linear (R2 > 0.99). Results obtained by NMR were compared with those obtained using the conventional gas chromatographic method. No significant differences were found between the means and precisions of the two techniques (P < 0.05). The method is well-suited for the routine quantification of these acids, requires no sample pretreatment and is more rapid than gas chromatography. Key words: Volatile fatty acid determination, rumen fluid, gas chromatography, nuclear magnetic resonance spectroscopy

Стилі APA, Harvard, Vancouver, ISO та ін.

4

Liu, Z., B. W. McBride, A. Lirette, R. W. Fairfull, and M. Brauer. "Phosphorus-31 nuclear magnetic resonance spectroscopy of liver from two broiler chicken lines." Canadian Journal of Animal Science 74, no. 4 (December 1, 1994): 687–94. http://dx.doi.org/10.4141/cjas94-099.

Повний текст джерела

Анотація:

Hepatic levels of phosphorus-containing compounds that are related to fat metabolism in the liver of two broiler lines with different body-fat content were assessed using high-resolution 31P NMR spectroscopy. PCA extracts of livers from 16-d-old chicks were analyzed with an NMR spectrometer. The results demonstrated that the concentrations of G3P, AMP and phosphocholine were significantly higher in the livers of LL birds than in those of the FL birds (P < 0.05). Differences in hepatic concentration of GPE and GPC were not detected between the two lines. It was also found that the liver weight per unit body weight of the FL chickens was less than that of the LL birds (P < 0.01). Average body weight of FL birds at 16 d of age was lighter than that of LL birds (P = 0.01). The FL birds deposited more (P < 0.05) fat per unit body weight than the LL birds. However, no statistical difference (P > 0.05) was found in protein deposition per unit body weight between the two lines. These results indicate that liver size and the concentration of hepatic phosphorus containing compounds are related to the partition of energy in broiler chickens. Key words: NMR spectroscopy, phosphorus-containing compounds, fat deposition, liver, broiler chicken

Стилі APA, Harvard, Vancouver, ISO та ін.

5

Vardhan, Nafady, Al-Enizi, Khandker, El-Sagher, Verma, Acevedo-Duncan, Alotaibi, and Ma. "Investigation of the Anticancer Activity of Coordination-Driven Self-AssembledTwo-Dimensional Ruthenium Metalla-Rectangle." Molecules 24, no. 12 (June 19, 2019): 2284. http://dx.doi.org/10.3390/molecules24122284.

Повний текст джерела

Анотація:

Coordination-driven self-assembly is an effective synthetic tool for the construction of spatially and electronically tunable supramolecular coordination complexes (SCCs), which are useful in various applications. Herein, we report the synthesis of a two-dimensional discrete metalla-rectangle [(η6-p-cymene)4Ru4(C6H2O4)2(2)2](CF3SO3)4 (3) by the reaction of a dinuclear half-sandwich ruthenium (II) complex [Ru2(η6-p-cymene)2(C6H2O4)Cl2] (1) and bis-pyridyl amide linker (2) in the presence of AgO3SCF3. This cationic ruthenium metalla-rectangle (3) has been isolated as its triflate salt and characterized by analytical techniques including elemental analysis, Fourier-transform infrared spectroscopy (FT-IR), proton nuclear magnetic resonance spectroscopy (1H-NMR), carbon nuclear magnetic resonance spectroscopy (13C-NMR), 1H-1H correlation spectroscopy (COSY), 1H-1H nuclear Overhauser effect spectroscopy (NOESY), diffusion ordered spectroscopy (DOSY), and high-resolution electrospray ionization mass spectrometry (HR-ESI-MS). Significantly, the 2D cationic ruthenium metalla-rectangle showed better anticancer activity towards three different cell lines (A549, Caki-1 and Lovo) as compared with the parent ruthenium complex (1) and the commercially used drug, cisplatin.

Стилі APA, Harvard, Vancouver, ISO та ін.

6

Zhang, Shan-Shan, Niu-Niu Zhang, Sen Guo, Shao-Jing Liu, Yu-Fei Hou, Shiming Li, Chi-Tang Ho, and Nai-Sheng Bai. "Glycosides and flavonoids from the extract of Pueraria thomsonii Benth leaf alleviate type 2 diabetes in high-fat diet plus streptozotocin-induced mice by modulating the gut microbiota." Food & Function 13, no. 7 (2022): 3931–45. http://dx.doi.org/10.1039/d1fo04170c.

Повний текст джерела

Анотація:

Twenty glycoside derivatives and nine flavonoids from the leaves of Pueraria (P. thomsonii) were isolated by column chromatography and characterized by nuclear magnetic resonance spectroscopy (NMR) and high performance liquid chromatography (HPLC).

Стилі APA, Harvard, Vancouver, ISO та ін.

7

Okunieff, P., M. D. Greenberg, A. Zietman, J. Kahn, S. Westgate, and L. J. Neuringer. "Failure of 1H nuclear magnetic resonance spectroscopy of blood plasma to detect malignancy." Journal of Clinical Oncology 8, no. 5 (May 1990): 906–10. http://dx.doi.org/10.1200/jco.1990.8.5.906.

Повний текст джерела

Анотація:

Water-suppressed proton nuclear magnetic resonance (NMR) of plasma was proposed as a technique for detecting malignant tumors. In that analysis, bloods drawn from cancer patients at the Beth Israel Hospital (BIH; Boston, MA), were easily distinguished from normal subjects by measuring and averaging the proton NMR methyl and methylene line widths of plasma lipoproteins. We collected blood at the Massachusetts General Hospital (MGH), including from normal controls, patients with untreated and treated malignant tumors, and patients with nontumor diseases. The plasma NMR analyses were carried out blind. The code was not broken until all patient charts and pathology records were reviewed, plasma analyses were completed, and patients had been divided into appropriate clinical groups. Analysis of these data showed no differences between the means of the study groups (false-positive and false-negative frequencies 46% and 57%, respectively). An inverse correlation of methyl/methylene line widths with age (P less than .01), and a correlation with nitrate-requiring cardiovascular disease (P less than .05) was, however, evident. This test cannot be validly used to detect malignancy.

Стилі APA, Harvard, Vancouver, ISO та ін.

8

Ullah, Ubaid, Safia Bano, and Shoaib Saleem. "Evaluation of Central Nervous System Tuberculomas by Using Modern Diagnostic Techniques." Pakistan Journal of Medical and Health Sciences 16, no. 6 (June 22, 2022): 16–18. http://dx.doi.org/10.53350/pjmhs2216616.

Повний текст джерела

Анотація:

Aim: To assess central nervous system tuberculomas by using modern MRI techniques such as Diffusion MRI (dMRI), Nuclear magnetic resonance spectroscopy (NMR spectroscopy) and BOLD venographic imaging. Study design: A retrospective study design Study setting: From 5th Feb 2021 to 5th Feb 2022 at the department of Neurology of Ibe-e-Siena Hospital, Multan. Methods: A retrospective study was conducted in the neurology department of Ibe-e-Siena Hospital & Research Institute Multan from 5th February 2021 to 5th February 2022. A total of 100 patients with suspected intracranial tuberculomas were included in the study. Advanced MRI techniques, including Diffusion MRI (dMRI), Nuclear magnetic resonance spectroscopy (NMR spectroscopy) and BOLD venographic imaging and conventional MRI, was performed on the patients. The study was approved by the ethical committee of the hospital, and all the patients provided their written consent for inclusion in the study Results: NMR spectroscopy evaluation showed that N-acetylaspartate /Creatine and N-acetylaspartate /Choline ratios of tuberculomas did not differ significantly from malignant brain lesions (p>0.04). But the malignant brain lesion (2.59) were significantly higher than the Choline/Creatine ratio of tuberculomas(1.29). BOLD venographic imaging evaluation showed no hypointense peripheral ring in malignant brain lesions but showed complete and regular rings in 36 (58.1%) of tuberculomas. Conclusion: Diffusion MRI did not help distinguish tuberculomas from metastasis and gliomas. However, NMR spectroscopy did offer this advantage by evaluating their unique metabolite pattern. BOLD venographic imaging showed the presence of a complete peripheral hypointense ring helping in diagnosing tuberculomas Keywords: Intracranial tuberculomas, Nuclear magnetic resonance spectroscopy, diffusion MRI,

Стилі APA, Harvard, Vancouver, ISO та ін.

9

Bajju, Gauri D., Deepmala, Sunil Kumar Anand, Sujata Kundan, and Narinder Singh. "Electrochemical and Spectroscopic Characterization of Aluminium(III)-para-methyl-meso-tetraphenylporphyrin Complexes Containing Substituted Salicylates as Axial Ligands." International Journal of Electrochemistry 2013 (2013): 1–10. http://dx.doi.org/10.1155/2013/409375.

Повний текст джерела

Анотація:

A series of aluminium(III)-p-methyl-meso-tetraphenylporphyrin (p-CH3TPP-Al(III)) containing axially coordinated salicylate anion [p-CH3TPP-Al-X)], where X = salicylate (SA), 4-chlorosalicylate (4-CSA), 5-chlorosalicylate (5-CSA), 5-flourosalicylate (5-FSA), 4-aminosalicylate (4-ASA), 5-aminosalicylate (5-ASA), 5-nitrosalicylate (5-NSA), and 5-sulfosalicylate (5-SSA), have been synthesized and characterized by various spectroscopic techniques including ultraviolet-visible (UV-vis), infrared (IR) spectroscopy, proton nuclear magnetic resonance (1H NMR) spectroscopy,13C NMR, and elemental analysis. A detailed study of electrochemistry of all the synthesized compounds has been done to compare their oxidation and reduction mechanisms and to explain the effect of axial coordination on their redox properties.

Стилі APA, Harvard, Vancouver, ISO та ін.

10

Szerb, Elisabeta I., Réka-Anita Domokos, Carmen Creţu, Massimo La Deda, and Vasile Chiş. "Vibrational and Nuclear Magnetic Resonance Properties of 2,2′-Biquinolines: Experimental and Computational Spectroscopy Study." Journal of Nanoscience and Nanotechnology 21, no. 4 (April 1, 2021): 2404–12. http://dx.doi.org/10.1166/jnn.2021.18969.

Повний текст джерела

Анотація:

Experimental (IR, Raman and NMR) techniques and quantum chemical (DFT) methods have been applied to investigate the vibrational and NMR properties of a new ligand based on 2,2′-biquinoline (bq) functionalized with polar hydrophilic tetraethylene glycol monomethylether (TEG) chains (bq_TEG). Vibrational and NMR spectra of the ligand have been explained based on DFT computational data obtained at B3LYP/6-311+G(d,p) level of theory. For the spectroscopic analysis we started from the parent molecule 2,2′-biquinoline and explained the changes in the spectra of bq_TEG in close relation to the corresponding spectra of bq. Our data point to a trans conformation of bq_TEG in solid state, as wells as in liquid phase. The excellent agreement between the experimental and computed data allowed for a reliable assignment of the vibrational and NMR spectra, both for bq and bq_TEG.

Стилі APA, Harvard, Vancouver, ISO та ін.

11

Bettjeman, Bodhi I., Kathleen A. Hofman, Elaine J. Burgess, Nigel B. Perry, and Daniel P. Killeen. "Seafood Phospholipids: Extraction Efficiency and Phosphorous Nuclear Magnetic Resonance Spectroscopy (31 P NMR) Profiles." Journal of the American Oil Chemists' Society 95, no. 7 (July 2018): 779–86. http://dx.doi.org/10.1002/aocs.12086.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

12

Zhang, Jing, and Huaibo Ma. "Synthesis, Characterization, and Crystal Structures of Imides Condensed with p-Phenylamino(Phenyl) Amine and Fluorescence Property." Materials 12, no. 11 (June 10, 2019): 1873. http://dx.doi.org/10.3390/ma12111873.

Повний текст джерела

Анотація:

A series of aromatic diimide and monoimide compounds condensed with p-phenylamino(phenyl)amine were synthesized and confirmed by Proton Nuclear Magnetic Resonance (1H NMR), Carbon-13 Nuclear Magnetic Resonance (13C NMR), Fourier Transform Infrared Spectroscopy (FT-IR), Elemental Analysis (EA), and High Resolution Mass Spectroscopy (HRMS). Meanwhile, single crystal X-ray diffraction showed the existence of intermolecular N···O hydrogen bonds, which affected the thermal stabilities of corresponding compounds by the support of Thermalgravimetric Analysis (TGA) curves. The steady-state UV-vis absorption peaks of synthetic compounds 1–6 appeared in the range of 220–380 nm. Fluorescence emission spectra showed peaks in the range of 290–420 nm. Meanwhile, deep-blue or violet-blue emissions for 2, 4, and 5 in THF under excitations of 254 nm and 365 nm, respectively, were observed at room temperature in air. Furthermore, Differential pulse voltammetry (DPV) and cyclic voltammogram CV were conducted within −1.5–+1.5 V to show quasi-reversible behavior for conjugated compounds and irreversible behavior for less conjugated ones.

Стилі APA, Harvard, Vancouver, ISO та ін.

13

Lirette, A., Z. Liu, D. C. Crober, R. A. Towner, U. M. Oehler, E. G. Janzen, J. R. Chambers, et al. "Magnetic resonance imaging (1H) and spectroscopy (1H, 31P) of growing chicken embryos." Canadian Journal of Animal Science 73, no. 4 (December 1, 1993): 953–65. http://dx.doi.org/10.4141/cjas93-096.

Повний текст джерела

Анотація:

Nuclear magnetic resonance (NMR) imaging and spectroscopy techniques were used to observe in vivo anatomical and metabolite changes, respectively, in developing chicken embryos. Proton (1H) NMR images of the eggs revealed major changes in yolk shape from day 2 to day 6. Embryos were visible from day 6 to hatching, and good embryonic anatomical images were obtained. Two peaks were observed from 1H-NMR spectroscopy of fertilized eggs: one for lipid methylene protons, and one for water protons. Water peak to lipid peak ratios did not vary significantly (P > 0.05) from day 2 to day 21 of incubation. Localized 31P-NMR spectra of developing embryos were obtained with either a 31P surface coil or a double-tuned 31P/1H volume coil. The surface-coil method gave a greater signal to noise ratio by a factor of four. The 31P-NMR spectra indicated two peaks at day 2; these were attributed to phosphomonoesters and phosphodiesters. The three peaks characteristic of ATP appeared on day 11 and increased in size until hatching. From day 19, phosphocreatine was detectable. There appeared to be a good correlation between 31P-metabolite changes detected by in vivo 31P-NMR spectroscopy and literature values for biochemical analyses of developing chicken embryos. The advantage in using NMR imaging and spectroscopy techniques is that anatomical and metabolic changes can be obtained in vivo, non-invasively and repeatedly as an embryo develops. Key words: NMR, MRI, embryo, poultry

Стилі APA, Harvard, Vancouver, ISO та ін.

14

Reitzel, Kasper, Joakim Ahlgren, Adolf Gogoll, Henning S. Jensen, and Emil Rydin. "Characterization of phosphorus in sequential extracts from lake sediments using 31P nuclear magnetic resonance spectroscopy." Canadian Journal of Fisheries and Aquatic Sciences 63, no. 8 (August 1, 2006): 1686–99. http://dx.doi.org/10.1139/f06-070.

Повний текст джерела

Анотація:

Phosphorus (P) compounds in three different lake surface sediments were extracted by sequential P extraction and identified by 31P nuclear magnetic resonance (31P NMR) spectroscopy. The extraction procedure primarily discriminates between inorganic P-binding sites but most extraction steps also contained P not reacting (nrP) with the molybdenum complex during P analyses. In all three lakes, the nrP dominated in the NaOH extracts. Nonreactive P from the dystrophic lake was dominated by potentially recalcitrant P groups such as orthophosphate monoesters, while the nrP in the two more productive lakes also contained polyphosphates, pyrophosphate, and organic P groups such as P lipids and DNA-P that may be important in remineralization and recycling to the water column. In addition, polyphosphates showed substantial dynamics in settling seston. The Humic-P pools (P associated with humic acids) showed strong signals of orthophosphate monoesters in all three lakes, which supported the assumption that P-containing humic compounds are indeed recovered in this fraction, although other organic P forms are also present. Thus, in addition to expanding the understanding of which organic P forms that are present in lake sediments, the 31P NMR technique also demonstrated that the chemical extraction procedure may provide some quantification of recalcitrant versus labile organic P forms.

Стилі APA, Harvard, Vancouver, ISO та ін.

15

Bao, Jin-ping, Cui-lian Xu, Guo-yu Yang, Cai-xia Wang, Xin Zheng, and Xin-xin Yuan. "Novel 6a,12b-Dihydro-6H,7H-chromeno[3,4-c] chromen-6-ones: Synthesis, Structure and Antifungal Activity." Molecules 24, no. 9 (May 5, 2019): 1745. http://dx.doi.org/10.3390/molecules24091745.

Повний текст джерела

Анотація:

A new series of coumarin derivatives, 7-hydroxy-7-(trifluoromethyl)-6a,12b-dihydro-6H,7H-chromeno[3,4-c]chromen-6-ones 3a–p, were synthesized via Michael addition, transesterification and nucleophilic addition from the reaction of 3-trifluoroacetyl coumarins and phenols in the presence of an organic base. The products were characterized by infrared spectroscopy (IR), hydrogen nuclear magnetic resonance spectroscopy (1H-NMR), carbon nuclear magnetic resonance spectroscopy (13C-NMR) and high-resolution mass spectrometer (HRMS). Single crystal X-ray analysis of compounds 3a and 3n clearly confirmed their assigned chemical structures and their twisted conformations. Compound 3a crystallized in the orthorhombic system, Pbca, in which a = 8.6244(2) Å, b = 17.4245(4) Å, c = 22.5188(6) Å, α = 90°, β = 90°, γ = 90°, v = 3384.02(14) Å3, and z = 8. In addition, the mycelial growth rate method was used to examine the in vitro antifungal activities of the title compounds 3a–p against Fusarium graminearum and Fusarium monitiforme at 500 µg/mL. The results showed that compound 3l exhibited significant anti-Fusarium monitiforme activity with inhibitory index of 84.6%.

Стилі APA, Harvard, Vancouver, ISO та ін.

16

Reid, Joel, Toby Bond, Shiliang Wang, Jigang Zhou, and Anguang Hu. "Synchrotron powder diffraction, X-ray absorption and 1H nuclear magnetic resonance data for hypoxanthine, C5H4N4O." Powder Diffraction 30, no. 3 (August 13, 2015): 278–85. http://dx.doi.org/10.1017/s0885715615000457.

Повний текст джерела

Анотація:

Synchrotron powder X-ray diffraction, X-ray absorption spectroscopy (XAS), and proton nuclear magnetic resonance (1H-NMR) data have been used to examine the structure of hypoxanthine, 1,7-dihydro-6H-purin-6-one (C5H4N4O), a purine base that participates in numerous metabolic processes. XAS and 1H-NMR spectroscopy were used to determine that hypoxanthine was present in its keto form (both in solid state and dissolved in an organic solvent). Rigid body refinement was performed with the Rietveld software package GSAS yielding triclinic lattice parameters of a = 7.1179 (2) Å, b = 9.7830 (3) Å, c = 10.4009 (3) Å, α = 58.876 (1)°, β = 67.609 (1)°, and γ = 71.937 (2)° (C5H4N4O, Z = 4, space group P$\bar 1$).

Стилі APA, Harvard, Vancouver, ISO та ін.

17

Lawson, Barry, Endla K. Anday, Ronnie Guillet, L. Craig Wagerle, Eileen Donlon, Britton Chance, and Maria Delivoria-Papadopoulos. "1435 EFFECT OF VARYING HEAD POSITION ON CEREBRAL 31-P NUCLEAR MAGNETIC RESONANCE (NMR) SPECTROSCOPY." Pediatric Research 19, no. 4 (April 1985): 350A. http://dx.doi.org/10.1203/00006450-198504000-01459.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

18

Brow, R. K., Z. A. Osborne, and R. J. Kirkpatrick. "A multinuclear MAS NMR study of the short-range structure of fluorophosphate glass." Journal of Materials Research 7, no. 7 (July 1992): 1892–99. http://dx.doi.org/10.1557/jmr.1992.1892.

Повний текст джерела

Анотація:

We have examined the bonding arrangements in Na–P–O–F and Na–Al–P–O–F glasses using 19F, 27Al, and 31P solid-state magic angle spinning nuclear magnetic resonance (MAS NMR) spectroscopy. For the Al-free series of glasses, the 19F NMR spectra are dominated by peaks near +90 ppm, representative of F terminating P-chains. The formation of these bonds has little effect on the 31P chemical shifts, indicating that F preferentially replaces bridging oxygen on the phosphate tetrahedra, consistent with previous NMR studies of crystalline fluorophosphates and other spectroscopic studies of fluorophosphate glass. For the Na–Al–P–O–F glasses, 27Al NMR detects only octahedral Al-sites, the 19F NMR spectra include a second peak near −12 ppm due to F bonded to Al, and the 31P NMR spectra contain signals due to Q1-sites with one or more Al next-nearest neighbors. The relative intensity of the two 19F peaks correlates well with previous spectroscopic studies and shows that a greater fraction of F–P bonds forms when the base glass is remelted in NH4HF2.

Стилі APA, Harvard, Vancouver, ISO та ін.

19

Toussaint, Jean-François, Kenneth K. Kwong, Fidelis M’Kparu, Robert M. Weisskoff, Paul J. Laraia, and Howard L. Kantor. "Interrelationship of oxidative metabolism and local perfusion demonstrated by NMR in human skeletal muscle." Journal of Applied Physiology 81, no. 5 (November 1, 1996): 2221–28. http://dx.doi.org/10.1152/jappl.1996.81.5.2221.

Повний текст джерела

Анотація:

Toussaint, Jean-François, Kenneth K. Kwong, Fidelis M’Kparu, Robert M. Weisskoff, Paul J. LaRaia, and Howard L. Kantor.Interrelationship of oxidative metabolism and local perfusion demonstrated by NMR in human skeletal muscle. J. Appl. Physiol. 81(5): 2221–2228, 1996.—Using nuclear magnetic resonance (NMR), we have examined the relationship of high-energy phosphate metabolism and perfusion in human soleus and gastrocnemius muscles. With31P-NMR spectroscopy, we monitored phosphocreatine (PCr) decay and recovery in eight normal volunteers and four heart failure patients performing ischemic plantar flexion. By using echo-planar imaging, perfusion was independently measured by a local [inversion-recovery (T1-flow)] and a regional technique (NMR-plethysmography). After correction for its pH dependence, PCr recovery time constant is 27.5 ± 8.0 s in normal volunteers, with mean flow 118 ± 75 (soleus and gastrocnemius T1-flow) and 30.2 ± 9.7 ml ⋅ 100 ml−1 ⋅ min−1(NMR-plethysmography-flow). We demonstrate a positive correlation between PCr time constant and local perfusion given by y = 50 − 0.15 x( r 2 = 0.68, P = 0.01) for the 8 normal subjects, and y = 64 − 0.24 x( r 2 = 0.83, P = 0.0001) for the 12 subjects recruited in the study. Regional perfusion techniques also show a significant but weaker correlation. Using this totally noninvasive method, we conclude that aerobic ATP resynthesis is related to the magnitude of perfusion, i.e., O2availability, and demonstrate that magnetic resonance imaging and magnetic resonance spectroscopy together can accurately assess muscle functional status.

Стилі APA, Harvard, Vancouver, ISO та ін.

20

Nyquist, R. A. "IR and NMR Correlations for 3-x and 4-x Substituted Anilines." Applied Spectroscopy 47, no. 4 (April 1993): 411–22. http://dx.doi.org/10.1366/0003702934334976.

Повний текст джерела

Анотація:

Infrared (IR) and/or Nuclear Magnetic Resonance (NMR) carbon-13 data are presented for 3- x and 4- x substituted anilines. Correlations are presented for the δ13C-1 chemical shift vs. Hammett δ p and δ m values, vasym., NH2 vs. δ13C-1, vsym. NH2 vs. δ13C-1, δ13C-1 vs. vasym. NH2, δ13C-1 vs. the absorbance ratio A( vasym. NH2/ A( vsym. NH2), and δ13C-l vs. Taft δ R°. The IR data for these compounds are recorded in the vapor phase, and in hexane, carbon tetrachloride, and chloroform solutions. The NMR chemical shift data for these compounds in solution with chloroform were obtained with the use of tetramethylsilane as the δ13C resonance reference frequency.

Стилі APA, Harvard, Vancouver, ISO та ін.

21

Zloh, Mire. "NMR spectroscopy in drug discovery and development: Evaluation of physico-chemical properties." ADMET and DMPK 7, no. 4 (December 10, 2019): 242–51. http://dx.doi.org/10.5599/admet.737.

Повний текст джерела

Анотація:

Determination of physico-chemical properties of compounds is one of the corner-stones in selection of hit molecules for further progression into lead development in the modern drug discovery process. The speed of traditional analyses and limited quantities of hit molecules are obstacles for efficient acquisition of experimental data. Herein, the range of applications of quantitative nuclear magnetic resonance (NMR) spectroscopy as a fast technique used to evaluate solubility, log P and pKa are discussed.

Стилі APA, Harvard, Vancouver, ISO та ін.

22

Ashaduzzaman, Md, Kei Ishikura, Masayo Sakata, and Masashi Kunitake. "Surface Initiated ATRP: Synthesis and Characterization of Functional Polymers Grafted on Modified Cellulose Beads." International Letters of Chemistry, Physics and Astronomy 13 (May 3, 2013): 243–48. http://dx.doi.org/10.56431/p-31s0tq.

Повний текст джерела

Анотація:

Atom transfer radical polymerization (ATRP) was employed to synthesize novel polymer particles. The surface of porous polymeric cellulose beads was modified by sodium hydroxide, 2-chloromethyloxirane, ethylenediamine and 2-bromo-2-methylpropionyl bromide successively in order to activate the beads surface so that it can play an important role as an initiator for ATRP reaction. ATRP on the modified cellulose beads surface was carried out with styrene and sodium p-styrenesulphonate monomers in the presence of non aqueous and aqueous phases respectively. The polymer products on the substrate surface were characterized by elemental analysis (EA), attenuated total reflectance-infrared (ATR-IR) spectroscopy and carbon13 – nuclear magnetic resonance (13C-NMR).

Стилі APA, Harvard, Vancouver, ISO та ін.

23

Reichhardt, Courtney, Jose A. G. Ferreira, Lydia-Marie Joubert, Karl V. Clemons, David A. Stevens, and Lynette Cegelski. "Analysis of the Aspergillus fumigatus Biofilm Extracellular Matrix by Solid-State Nuclear Magnetic Resonance Spectroscopy." Eukaryotic Cell 14, no. 11 (July 10, 2015): 1064–72. http://dx.doi.org/10.1128/ec.00050-15.

Повний текст джерела

Анотація:

ABSTRACTAspergillus fumigatusis commonly responsible for lethal fungal infections among immunosuppressed individuals.A. fumigatusforms biofilm communities that are of increasing biomedical interest due to the association of biofilms with chronic infections and their increased resistance to antifungal agents and host immune factors. Understanding the composition of microbial biofilms and the extracellular matrix is important to understanding function and, ultimately, to developing strategies to inhibit biofilm formation. We implemented a solid-state nuclear magnetic resonance (NMR) approach to define compositional parameters of theA. fumigatusextracellular matrix (ECM) when biofilms are formed in RPMI 1640 nutrient medium. Whole biofilm and isolated matrix networks were also characterized by electron microscopy, and matrix proteins were identified through protein gel analysis. The13C NMR results defined and quantified the carbon contributions in the insoluble ECM, including carbonyls, aromatic carbons, polysaccharide carbons (anomeric and nonanomerics), aliphatics, etc. Additional15N and31P NMR spectra permitted more specific annotation of the carbon pools according to C-N and C-P couplings. Together these data show that theA. fumigatusECM produced under these growth conditions contains approximately 40% protein, 43% polysaccharide, 3% aromatic-containing components, and up to 14% lipid. These fundamental chemical parameters are needed to consider the relationships between composition and function in theA. fumigatusECM and will enable future comparisons with other organisms and withA. fumigatusgrown under alternate conditions.

Стилі APA, Harvard, Vancouver, ISO та ін.

24

Di Matteo, Giacomo, Mattia Spano, Cristina Esposito, Cristina Santarcangelo, Alessandra Baldi, Maria Daglia, Luisa Mannina, Cinzia Ingallina, and Anatoly P. Sobolev. "NMR Characterization of Ten Apple Cultivars from the Piedmont Region." Foods 10, no. 2 (February 1, 2021): 289. http://dx.doi.org/10.3390/foods10020289.

Повний текст джерела

Анотація:

The metabolite profile of ten traditional apple cultivars grown in the Piedmont region (Italy) was studied by means of nuclear magnetic resonance spectroscopy, identifying an overall number of 36 compounds. A more complete assignment of the proton nuclear magnetic resonance (1H NMR) resonances from hydroalcoholic and organic apple extracts with respect to literature data was reported, identifying fructose tautomeric forms, galacturonic acid, γ-aminobutyric acid (GABA), p-coumaroyl moiety, phosphatidylcholine, and digalactosyldiacylglycerol. The chemical profile of each apple cultivar was defined by thorough quantitative NMR analysis of four sugars (fructose, glucose, sucrose, and xylose), nine organic acids (acetic, citric, formic, citramalic, lactic, malic, quinic, and galacturonic acids), six amino acids (alanine, asparagine, aspartate, GABA, isoleucine, and valine), rhamnitol, p-coumaroyl derivative, phloretin/phloridzin and choline, as well as β-sitosterol, fatty acid chains, phosphatidylcholine, and digalactosyldiacylglycerol. Finally, the application of PCA analysis allowed us to highlight possible differences/similarities. The Magnana cultivar showed the highest content of sugars, GABA, valine, isoleucine, and alanine. The Runsé cultivar was characterized by high amounts of organic acids, whereas the Gamba Fina cultivar showed a high content of chlorogenic acid. A significant amount of quinic acid was detected in the Carla cultivar. The knowledge of apple chemical profiles can be useful for industries interested in specific compounds for obtaining ingredients of food supplements and functional foods and for promoting apple valorization and preservation.

Стилі APA, Harvard, Vancouver, ISO та ін.

25

Sarty, Gordon E., Edward J. Kendall, Gregg P. Adams, and Roger A. Pierson. "Nuclear magnetic resonance spectroscopy of bovine ovarian follicular fluid at four selected times of the oestrous cycle." Reproduction, Fertility and Development 18, no. 5 (2006): 559. http://dx.doi.org/10.1071/rd06010.

Повний текст джерела

Анотація:

The objective of the study was to determine if nuclear magnetic resonance (NMR) spectral features of ovarian follicular fluid were correlated with the physiological status of follicles so that we could assess the feasibility of using NMR spectroscopy during assisted reproduction therapy. Thirty-five sexually mature, nullparious heifers were monitored by transrectal ultrasonography to assess their follicle wave status during the oestrous cycle. Ovariectomies were performed on Day 3 of wave 1 (D3W1, n = 10), Day 6 of wave 1 (D6W1, n = 9), Day 1 of wave 2 (D1W2, n = 9), or in the immediate preovulatory period of at least 17 days after ovulation (D≥17, n = 9). Follicle status was determined to be dominant or subordinate. Follicular fluid was extracted from the follicles and NMR spectra were collected. Principal components were extracted from ratios of line amplitudes and tested for effects of follicle status (dominant v. subordinate) and cycle time point (D1W3, D1W6, D1W2 and D≥17) using multivariate analysis of variance. For most line ratio combinations, main effects of status, time point and their interaction were found (P < 0.05). We concluded that NMR spectra may be used for the determination of ovarian follicle physiological status.

Стилі APA, Harvard, Vancouver, ISO та ін.

26

CHUNG, CECILIA P., ANNETTE OESER, PAOLO RAGGI, TUULIKKI SOKKA, THEODORE PINCUS, JOSEPH F. SOLUS, MACRAE F. LINTON, SERGIO FAZIO, and C. MICHAEL STEIN. "Lipoprotein Subclasses Determined by Nuclear Magnetic Resonance Spectroscopy and Coronary Atherosclerosis in Patients with Rheumatoid Arthritis." Journal of Rheumatology 37, no. 8 (June 1, 2010): 1633–38. http://dx.doi.org/10.3899/jrheum.090639.

Повний текст джерела

Анотація:

Objective.Patients with rheumatoid arthritis (RA) are at increased risk of atherosclerosis, but routine lipid measurements differ little from those of people without RA. We examined the hypothesis that lipid subclasses determined by nuclear magnetic resonance spectroscopy (NMR) differed in patients with RA compared to controls and are associated with disease activity and the presence of coronary-artery atherosclerosis.Methods.We measured lipoprotein subclasses by NMR in 139 patients with RA and 75 control subjects. Lipoproteins were classified as large low-density lipoprotein (LDL; diameter range 21.2–27.0 nm), small LDL (18.0–21.2 nm), large high-density lipoprotein (HDL; 8.2–13.0 nm), small HDL (7.3–8.2 nm), and total very low-density lipoprotein (VLDL; ≥ 27 nm). All subjects underwent an interview and examination; disease activity was quantified by the 28-joint Disease Activity Score (DAS28) and coronary artery calcification (CAC) was measured with electron-beam computed tomography.Results.Concentrations of small HDL particles were lower in patients with RA (18.2 ± 5.4 nmol/l) than controls (20.0 ± 4.4 nmol/l; p = 0.003). In patients with RA, small HDL concentrations were inversely associated with DAS28 (rho = −0.18, p = 0.04) and C-reactive protein (rho = −0.25, p = 0.004). Concentrations of small HDL were lower in patients with coronary calcification (17.4 ± 4.8 nmol/l) than in those without (19.0 ± 5.8 nmol/l; p = 0.03). This relationship remained significant after adjustment for the Framingham risk score and DAS28 (p = 0.025). Concentrations of small LDL particles were lower in patients with RA (1390 ± 722 nmol/l) than in controls (1518 ± 654 nmol/l; p = 0.05), but did not correlate with DAS28 or CAC.Conclusion.Low concentrations of small HDL particles may contribute to increased coronary atherosclerosis in patients with RA.

Стилі APA, Harvard, Vancouver, ISO та ін.

27

Morikawa, S., T. Inubushi, and K. Kito. "Heterogeneous Metabolic Changes in the Calf Muscle of the Rat during Ischaemia-reperfusion: in Vivo Analysis by ³¹P Nuclear Magnetic Resonance Chemical Shift Imaging and ¹H Magnetic Resonance Imaging." Cardiovascular Surgery 1, no. 4 (August 1993): 337–42. http://dx.doi.org/10.1177/096721099300100405.

Повний текст джерела

Анотація:

Non-localized and localized 31P nuclear magnetic resonance (NMR) spectra of rat calf muscle during arterial occlusion and after reperfusion were concurrently observed using chemical shift imaging and ‘H magnetic resonance imaging (MRI). During ischaemia. the levels of high-energy phosphates (phosphocreatine and adenosine 5′-triphosphate) were depleted and that of inorganic phosphate was increased. In addition, the signal intensity on 1H MRI was increased. These changes were observed to be relatively homogeneous throughout the calf. In contrast, the changes during reperfusion were heterogeneous. In the central part of the calf, inorganic phosphate disappeared, phosphocreatine was restored immediately on reperfusion and the ‘H signal was decreased. However, in the regions of the tibialis anterior muscle and the superficial part of the gastrocnemius muscle, inorganic phosphate persisted for several hours, phosphocreatine was not restored and the signal intensity on T2-weighted 1H MRI was increased further. The heterogeneous changes detected by 31P NMR spectroscopy and 1H MRI showed close agreement. The susceptibility of different calf muscles to ischaemia and reperfusion seems to depend on their predominant muscle fibre type (i.e. fast-twitch or slow-twitch fibres). Reversible and irreversible ischaemic changes could be non-invasively distinguished by in vivo31P NMR spectroscopy and 1H MRI.

Стилі APA, Harvard, Vancouver, ISO та ін.

28

Shumilina, Elena, Christian Andreasen, Zahra Bitarafan, and Alexander Dikiy. "Determination of Glyphosate in Dried Wheat by 1H-NMR Spectroscopy." Molecules 25, no. 7 (March 28, 2020): 1546. http://dx.doi.org/10.3390/molecules25071546.

Повний текст джерела

Анотація:

A wheat field was sprayed with a dosage of 1.1 kg a.i./ha Roundup PowerMax 10 days before harvest. The 1H Nuclear Magnetic Resonance (NMR) spectroscopy was used for the detection and quantification of the glyphosate (GLYP) in dried wheat spikelets, leaves, and stems. The quantification was done by the integration of the CH2-P groups doublet at 3.00 ppm with good linearity. The GLYP content varied between different samples and parts of the plant. On average, the largest content of herbicide was found in leaves (20.0 mg/kg), followed by stems (6.4 mg/kg) and spikelets (6.3 mg/kg). Our study shows that the 1H-NMR spectroscopy can be a rapid and reliable tool for GLYP detection and quantification in the field studies.

Стилі APA, Harvard, Vancouver, ISO та ін.

29

Bock, JL, B. Wenz, and RK Gupta. "Changes in intracellular Mg adenosine triphosphate and ionized Mg2+ during blood storage: detection by 31P nuclear magnetic resonance spectroscopy." Blood 65, no. 6 (June 1, 1985): 1526–30. http://dx.doi.org/10.1182/blood.v65.6.1526.bloodjournal6561526.

Повний текст джерела

Анотація:

Abstract 31P nuclear magnetic resonance (NMR) spectroscopy was used to measure changes in intra-erythrocyte Mg adenosine triphosphate (MgATP) and free Mg2+ during blood storage at 4 degrees C in standard citrate preservation media. The extent of Mg2+ complexation of ATP and the concentration of free Mg2+ were measured from the Mg2+-dependent chemical shift differences, at 22 degrees C, between the P beta and P alpha resonances of intracellular ATP. This difference changed from 721.0 +/- 1.4 Hz (mean +/- SE) on the day of collection to 741.0 +/- 3.4 Hz after three to seven days and 774.0 +/- 2.8 Hz after 11 to 40 days storage in either acid-citrate-dextrose (ACD) or citrate-phosphate- dextrose-adenine (CPDA-1). Changes in intracellular pH, detected from shifts in the intracellular Pi resonance, averaged 0.27 units after 11 to 40 days of storage. These data indicate a sizable decrease in the extent of Mg2+ complexation of ATP, and a decrease by a factor of 2.6 in free Mg2+, during the shelf-life of blood stored in ACD or CPDA-1.

Стилі APA, Harvard, Vancouver, ISO та ін.

30

Manríquez-Ramírez, Maria Elena, Carmen Magdalena Reza-San Germán, and Miriam Estrada-Flores. "Intercalation of p-toluenesulfonic acid into Mg-Al layered double hydroxide." Superficies y Vacío 35 (November 30, 2022): 221101. http://dx.doi.org/10.47566/2022_syv35_1-221101.

Повний текст джерела

Анотація:

Layered double hydroxide represents a class of materials for selective adsorption and catalysis. In the present work, anionic p-toluenesulfonic acid (PTSA) was successfully incorporated into the interlayer domain of Mg-Al layered double hydroxide (LDH), synthesized by the co-precipitation route. Materials were characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, Raman spectroscopy, magic angle nuclear magnetic resonance (13C MAS-NMR) spectroscopy and UV-Visible diffuse reflectance (UV-VIS/DR). All samples supported PTSA intercalation at room temperature in the basal space, the interlayer distance increased by the intercalations of the above mentioned according to the arrangement of PTSA molecules in the interlayer. The LDH-PTSA structure collapsed at 400 °C and the organic portion of those materials occurred by partial combustion, which in turn gives rise to reduced species, such as carbon and sulfide anions.

Стилі APA, Harvard, Vancouver, ISO та ін.

31

Özkundakci, Deniz, David P. Hamilton, Richard McDowell, and Stefan Hill. "Phosphorus dynamics in sediments of a eutrophic lake derived from 31P nuclear magnetic resonance spectroscopy." Marine and Freshwater Research 65, no. 1 (2014): 70. http://dx.doi.org/10.1071/mf13033.

Повний текст джерела

Анотація:

The determination of organic phosphorus (P) compounds in lake sediments can provide information on the potential for internal P loading. Settling seston and vertical sediment core samples from highly eutrophic Lake Okaro, New Zealand, were collected during a mixed winter and stratified summer period, representing, respectively, when the water column was well oxygenated and when the bottom waters were anoxic. Samples were analysed with 31P nuclear magnetic resonance (31P NMR) spectroscopy, which showed that both bottom sediments and settling seston contained orthophosphate, orthophosphate monoesters and diesters, pyrophosphates, polyphosphates and phosphonates. Phosphorus concentration in settling seston increased ~2.5-fold in winter as a result of seasonally induced changes in phytoplankton biomass, with a marked increase in the concentration of orthophosphate. Several potentially bioavailable P compounds in the bottom sediments were identified that were likely to contribute to recycling of P from the sediment to the water column. An ‘apparent half-life’ was used to quantify the time scales on which these compounds were recycled to the overlying water column. Orthophosphate monoesters that include inositol phosphates were the most persistent P compound. On the basis of half-lives, high internal P loadings may persist for more than 20 years, potentially hindering restoration efforts in Lake Okaro.

Стилі APA, Harvard, Vancouver, ISO та ін.

32

Zhang, Xiaoqian, Wenli Guo, Yibo Wu, Yuwei Shang, Shuxin Li, and Weihao Xiong. "Synthesis of random copolymer of isobutylene with p-methylstyrene by cationic polymerization in ionic liquids." e-Polymers 18, no. 5 (September 25, 2018): 423–31. http://dx.doi.org/10.1515/epoly-2018-0017.

Повний текст джерела

Анотація:

AbstractPoly(isobutylene-co-p-methylstyrene) (IB/p-MeSt) random copolymer is a new generation of polyisobutylene-based elastomer. The cationic copolymerization of IB with p-MeSt was thoroughly examined by using various initiating systems in [Hmim][NTf2] at −30°C. The effects of initiating systems and monomer feed ratio on the monomer conversion, molecular weight and copolymer composition are discussed. The polymers were characterized by 1H-nuclear magnetic resonance (NMR), Fourier transform infrared (FTIR) spectroscopy and matrix-assisted laser desorption/ionization-time-of-flight-mass spectroscopy (MALDI-TOF-MS) to determine their chemical composition and molecular structure. The results show that high polarity, high viscosity and ionic environment of ionic liquids (ILs) influenced the copolymerization. The corresponding mechanism of cationic copolymerization in ILs is also proposed.

Стилі APA, Harvard, Vancouver, ISO та ін.

33

Peeling, James, Garnette Sutherland, Kirk Marat, Edward Tomchuk, and Ernst Bock. "1H and 13C nuclear magnetic resonance studies of plasma from patients with primary intracranial neoplasms." Journal of Neurosurgery 68, no. 6 (June 1988): 931–37. http://dx.doi.org/10.3171/jns.1988.68.6.0931.

Повний текст джерела

Анотація:

✓ Plasma from patients with malignant and benign primary intracranial neoplasms and from healthy control subjects has been examined using proton (1H) and carbon-13 nuclear magnetic resonance (NMR) spectroscopy. Some features in the spectra of plasma from patients with malignant tumors differ significantly (p < 0.01) from the corresponding features in the spectra of plasma from control subjects and from patients with benign tumors. The NMR spectral parameters vary consistently with the Kernohan grade of astrocytoma, which may suggest that they give a measure of tumor growth kinetics. The observed spectral differences are shown to be due to elevated levels of monounsaturated and polyunsaturated fatty acid residues in the plasma of cancer patients. It is proposed that these lipid residues arise from cell membranes shed from cells in growing tumors. The ability to follow tumor growth kinetics directly may be of considerable importance in elucidating the effects of primary intracranial neoplasm therapy.

Стилі APA, Harvard, Vancouver, ISO та ін.

34

Vandenborne, K., G. Walter, L. Ploutz-Snyder, R. Staron, A. Fry, K. De Meirleir, G. A. Dudley, and J. S. Leigh. "Energy-rich phosphates in slow and fast human skeletal muscle." American Journal of Physiology-Cell Physiology 268, no. 4 (April 1, 1995): C869—C876. http://dx.doi.org/10.1152/ajpcell.1995.268.4.c869.

Повний текст джерела

Анотація:

We investigated the relationship between energy-rich phosphate content and muscle fiber-type composition in human skeletal muscle using a combination of 31P-nuclear magnetic resonance spectroscopy (NMR), histochemical, and biochemical analyses of muscle biopsies. Localized 31P spectra were collected simultaneously from the predominantly slow-twitch soleus muscle and the mixed (fast-twitch and slow-twitch) medial and lateral gastrocnemius muscles, using B1-insensitive Hadamard Spectroscopic Imaging. Biopsy samples were taken from the soleus and lateral gastrocnemius muscles before NMR investigation and analyzed for fiber type composition and succinic dehydrogenase (SDH) activity. Fiber-type composition was determined based both on myofibrillar actomyosin ATPase activity combined with cross-sectional area and on myosin heavy-chain composition. Localized spectroscopy demonstrated a significantly (P < 0.001) higher P(i)/phosphocreatine ratio in the soleus muscle (0.15 +/- 0.01) compared with the medial (0.12 +/- 0.01) and lateral (0.10 +/- 0.0) gastrocnemius. However, in vitro analysis of muscle biopsies showed only a moderate relationship between the basal phosphate content and myofibrillar actomyosin ATPase-based fiber-type composition and SDH activity, respectively.

Стилі APA, Harvard, Vancouver, ISO та ін.

35

Fletcher, Joseph P., Subhash H. Risbud, and R. James Kirkpatrick. "MASS-NMR structural analysis of barium aluminofluorophosphate glasses with and without nitridation." Journal of Materials Research 5, no. 4 (April 1990): 835–40. http://dx.doi.org/10.1557/jmr.1990.0835.

Повний текст джерела

Анотація:

The local structure of barium-aluminofluorophosphate (Ba–Al–P–O–F) glasses was investigated using high resolution magic-angle sample spinning nuclear magnetic resonance (MASS-NMR) spectroscopy. The 27Al spectra show three different aluminum environments [Al(4), Al(5), and Al(6)] in these glasses. Changes were observed due to the addition of fluorine and nitrogen. 31P results indicate only one type of phosphorus environment which shifts with fluorine additions. The 19F spectra suggest that fluorine has both Ba and Al as nearest neighbors.

Стилі APA, Harvard, Vancouver, ISO та ін.

36

Finster, P., J. Hollweg, and F. Seehofer. "Determination of Triacetin in Cigarette Filters by Pulsed Nuclear Magnetic Resonance Spectroscopy - Bestimmung von Triacetin in Zigarettenfiltern mit Hilfe der gepulsten Kernresonanzspektroskopie." Beiträge zur Tabakforschung International/Contributions to Tobacco Research 13, no. 5 (December 1, 1986): 255–64. http://dx.doi.org/10.2478/cttr-2013-0575.

Повний текст джерела

Анотація:

AbstractOur investigations show that pulsed nuclear magnetic resonance spectroscopy (p-NMR) is a suitable method of determining the triacetin content of freshly produced filter rods. The table-top pulse spectrometer tested in filter rod production distinguishes itself by the fact that it enables exact and reproducible direct measurements of whole filter rods to be made in seconds. There is no need for the whole process of preparing samples; after measurement the filters can be fed back into the production process. With the measuring method we have developed triacetin can be determined completely automatically, independent of sample weight and to a large extent independent of the moisture content of the filter material. The period of time between the triacetin application and the p-NMR measurement should be as short as possible and accurately reproducible.

Стилі APA, Harvard, Vancouver, ISO та ін.

37

He, Zhongqi, Mingxin Guo, Chanel Fortier, Xiaoyan Cao, and Klaus Schmidt-Rohr. "Fourier Transform Infrared and Solid State 13C Nuclear Magnetic Resonance Spectroscopic Characterization of Defatted Cottonseed Meal-Based Biochars." Modern Applied Science 15, no. 1 (January 15, 2021): 108. http://dx.doi.org/10.5539/mas.v15n1p108.

Повний текст джерела

Анотація:

Conversion to biochar may be a value-added approach to recycle defatted cottonseed meal, a major byproduct from the cotton industry. In this work, complete slow pyrolysis at seven peak temperatures ranging from 300 to 600°C in batch reactors was implemented to process cottonseed meal into biochar products. Elemental analysis, attenuated total reflection Fourier transform infrared (ATR FT-IR) spectroscopy and quantitative solid state 13C nuclear magnetic resonance (NMR) spectroscopy were applied to characterize raw meal and its derived biochar products. The biochar yield and organic C and total N recoveries decreased as the peak pyrolysis temperatures was elevated. However, most of the mineral elements including P in cottonseed meal were retained during pyrolysis and became enriched in biochar as a result of the decreased mass yield. The spectral data showed that pyrolysis removed the functional groups of biopolymers in cottonseed meal, producing highly aromatic structures in biochars. With increasing pyrolysis temperature, alkyl structures decreased progressively in the biochar products and became negligible at higher temperatures (550 and 600°C). Quantitative analysis of FT IR data revealed that the values of a simple 3-band (1800,1700, and 650 cm-1)-based R reading of the biochars were linearly related to the pyrolysis temperature, and showed strong correlations with decreasing aromaticity and increasing alkyl, aliphatic C-O/N and carbonyl signal intensities in the 13C NMR spectra. Therefore, the cheaper and faster FT-IR measurement could be used as a routine conversion indicator of pyrolysis of lignocellulosic biomass instead of the more expensive and time-consuming NMR spectroscopy.

Стилі APA, Harvard, Vancouver, ISO та ін.

38

Nadler, Melvin P., Robin A. Nissan, and Richard A. Hollins. "FT-IR and FT-NMR Study of Organophosphorus Surface Reactions." Applied Spectroscopy 42, no. 4 (May 1988): 634–42. http://dx.doi.org/10.1366/0003702884429463.

Повний текст джерела

Анотація:

Fourier transform infrared (FT-IR) and Fourier transform nuclear magnetic resonance (FT-NMR) methods were used to examine the adsorption and reaction of diisopropyl fluorophosphate (DFP) on various solid adsorbents. Static and flow system experiments were monitored with the use of FT-IR to determine DFP adsorption rates and isotherms on silica, coated silicas, γ-alumina, coated aluminas, and activated charcoal. The adsorption of DFP(g) onto the solid adsorbents was generally very rapid, with a half-life of 20 s for 1 mg DFP onto 25 mg of 350 m2/g silica. The DFP adsorption isotherm on silica indicated chemisorption to a monolayer at P/ P0 < 0.6, followed by increased coverage that appears to be physical adsorption. Diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy, photoacoustic spectroscopy (PAS), and solid-state 31P NMR of adsorbed DFP showed chemisorption on silica and on alumina. Bonding at the P=O of DFP was indicated by a −41 cm−1 shift in the v(P=O) and a 1-ppm upfield shift in the 31P resonance. DRIFT, PAS kinetics, and 31P NMR showed that DFP hydrolyzed after the initial adsorption on alumina and some coated materials but not on silica or activated charcoal. The rate of hydrolysis increased on alumina with addition of water and varied with different aluminas and coated silicas.

Стилі APA, Harvard, Vancouver, ISO та ін.

39

Rothman, Douglas L., Nicola R. Sibson, Fahmeed Hyder, Jun Shen, Kevin L. Behar, and Robert G. Shulman. "In vivo nuclear magnetic resonance spectroscopy studies of the relationship between the glutamate--glutamine neurotransmitter cycle and functional neuroenergetics." Philosophical Transactions of the Royal Society of London. Series B: Biological Sciences 354, no. 1387 (July 29, 1999): 1165–77. http://dx.doi.org/10.1098/rstb.1999.0472.

Повний текст джерела

Анотація:

In this article we review recent studies, primarily from our laboratory, using 13 C NMR (nuclear magnetic resonance) to non-invasively measure the rate of the glutamate-glutamine neurotransmitter cycle in the cortex of rats and humans. In the glutamate-glutamine cycle, glutamate released from nerve terminals is taken up by surrounding glial cells and returned to the nerve terminals as glutamine. 13 C NMR studies have shown that the rate of the glutamate-glutamine cycle is extremely high in both the rat and human cortex, and that it increases with brain activity in an approximately 1:1 molar ratio with oxidative glucose metabolism. The measured ratio, in combination with proposals based on isolated cell studies by P. J. Magistretti and co-workers, has led to the development of a model in which the majority of brain glucose oxidation is mechanistically coupled to the glutamate-glutamine cycle. This model provides the first testable mechanistic relationship between cortical glucose metabolism and a specific neuronal activity. We review here the experimental evidence for this model as well as implications for blood oxygenation level dependent magnetic resonance imaging and positron emission tomography functional imaging studies of brain function.

Стилі APA, Harvard, Vancouver, ISO та ін.

40

Mun-Bryce, S., F. O. Kroh, J. White, and G. A. Rosenberg. "Brain lactate and pH dissociation in edema: 1H- and 31P-NMR in collagenase-induced hemorrhage in rats." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 265, no. 3 (September 1, 1993): R697—R702. http://dx.doi.org/10.1152/ajpregu.1993.265.3.r697.

Повний текст джерела

Анотація:

Brain edema has been shown to increase brain lactate, but the effect on pH is unclear. We used in vivo nuclear magnetic resonance (NMR) spectroscopy to measure lactate and pH in a region of brain edema. Ninety-five anesthetized rats underwent proton and 31P-NMR spectroscopy with a 7-T 89-mm vertical bore spectrometer, using a surface coil over the edematous regions and distant from a hemorrhage produced by the injection of bacterial collagenase. Brain water content was measured from multiple regions after the NMR measurements in all rats. Lactate was significantly increased 4 h after the hemorrhage and remained elevated for 48 h, but brain pH was unaffected. The increase in lactate correlated (P < 0.01) with the increase in water content in the measured region. We conclude that lactate and pH are dissociated in a region of primarily vasogenic edema.

Стилі APA, Harvard, Vancouver, ISO та ін.

41

Samsonowicz, Mariola, Ewelina Gołębiewska, Elżbieta Wołejko, Urszula Wydro, Grzegorz Świderski, Joanna Zwolińska, Monika Kalinowska, and Włodzimierz Lewandowski. "Spectroscopic, Thermal, Microbiological, and Antioxidant Study of Alkali Metal 2-Hydroxyphenylacetates." Materials 14, no. 24 (December 17, 2021): 7824. http://dx.doi.org/10.3390/ma14247824.

Повний текст джерела

Анотація:

The structural, spectral, thermal, and biological properties of hydroxyphenylacetic acid and lithium, sodium, potassium, rubidium, and cesium 2-hydroxyphenylacetates were analyzed by means of infrared spectroscopy FT-IR, electronic absorption spectroscopy UV-VIS, nuclear magnetic resonance 1H and 13C NMR, thermogravimetric analysis (TG/DSC), and quantum-chemical calculations at B3LYP/6-311++G** level. Moreover, the antioxidant (ABTS, FRAP, and CUPRAC assays), antibacterial (against E. coli, K. aerogenes, P. fluorescens, and B. subtilis) and antifungal (against C. albicans) properties of studied compounds were measured. The effect of alkali metal ions on the structure, thermal, and biological properties of 2-hydroxyphenylacetates was discussed.

Стилі APA, Harvard, Vancouver, ISO та ін.

42

Luo, Chunhua, Meijuan Qian, and Qiujing Dong. "Synthesis and characterization of thermosensitive and polarity-sensitive fluorescent PNIPAM-coated gold nanoparticles." e-Polymers 17, no. 1 (January 1, 2017): 65–70. http://dx.doi.org/10.1515/epoly-2016-0247.

Повний текст джерела

Анотація:

AbstractThermosensitive PNIPAM-coated Au nanoparticles (AuNPs@P(NIPAM-co-MADMAC)) were synthesized by the radical “grafting through” copolymerization of 4-methacryloyloxy-4′-dimethylaminochalcone (MADMAC), MAEL-capped AuNPs and N-isopropylacrylamide (NIPAM) using azobisisobutyronitrile (AIBN) as the initiator. AuNPs@P(NIPAM-co-MADMAC) were characterized by transmission electron microscopy (TEM), ultraviolet-visible (UV-Vis) spectroscopy, thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), 1H nuclear magnetic resonance (NMR), and Fourier transform infrared (FTIR) spectroscopy. AuNPs@P(NIPAM-co-MADMAC) exhibited thermo-sensitivity from poly(NIPAM-co-MADMAC) chains and sensitive fluorescence from the MADMAC group. AuNPs@P(NIPAM-co-MADMAC) showed weak fluorescence after the temperature increased from 25°C to 45°C, or after β-cyclodextrin (β-CD) was added. Furthermore, it exhibited strong fluorescence when the solvent was changed to ethanol or chloroform.

Стилі APA, Harvard, Vancouver, ISO та ін.

43

Yoshioka, Yoshichika, Hiroshi Oikawa, Sigeru Ehara, Takashi Inoue, Akira Ogawa, Yoshiyuki Kambara, Shun-Ichi Itazawa, and Manabu Kubokawa. "Noninvasive Estimation of Temperature and pH in Human Lower Leg Muscles using1H Nuclear Magnetic Resonance Spectroscopy." Spectroscopy 16, no. 3-4 (2002): 183–90. http://dx.doi.org/10.1155/2002/392987.

Повний текст джерела

Анотація:

The temperature and pH of human lower leg muscles were estimated noninvasively using1H-NMR spectroscopy at 3.0 and 1.5 T on five normal volunteers (21M, 24M, 27M, 34M, 47M). The chemical shifts of water and imidazole protons relative to cholines (–N+CH3) or creatines (–CH3) could be used as the temperature and pH probes, respectively [1–4]. Using the chemical shift, estimated values of the temperature in gastrocnemius (GAS; shell region) and soleus muscles (SOL; core region) under ambient temperature (21–25°C) were 33.6±0.4 and 35.3±0.4°C (mean±SE), respectively (significantly different; P < 0.01). The values of pH in these muscles were estimated to be 6.97 ± 0.01 and 6.96 ± 0.02, respectively. Alternation of the surface temperature of the lower leg from 40 to 10°C significantly changed the temperature in GAS (P < 0.0001) from 35.8 ± 0.4 to 26.2 ± 1.2°C and the pH in GAS rose from 6.95 ± 0.01 to 7.01 ± 0.01 (P <0.01). However, the values of pH and temperature in SOL were not significantly affected by this maneuver. These results indicate that the pH in GAS was moderately changed by muscle temperature (r= –0.59, P <0.01), and its change was estimated to be –0.005 pH units/°C.

Стилі APA, Harvard, Vancouver, ISO та ін.

44

Peters, Thomas, Robert Creutznacher, Thorben Maass, Alvaro Mallagaray, Patrick Ogrissek, Stefan Taube, Lars Thiede, and Charlotte Uetrecht. "Norovirus–glycan interactions — how strong are they really?" Biochemical Society Transactions 50, no. 1 (December 23, 2021): 347–59. http://dx.doi.org/10.1042/bst20210526.

Повний текст джерела

Анотація:

Infection with human noroviruses requires attachment to histo blood group antigens (HBGAs) via the major capsid protein VP1 as a primary step. Several crystal structures of VP1 protruding domain dimers, so called P-dimers, complexed with different HBGAs have been solved to atomic resolution. Corresponding binding affinities have been determined for HBGAs and other glycans exploiting different biophysical techniques, with mass spectrometry (MS) and nuclear magnetic resonance (NMR) spectroscopy being most widely used. However, reported binding affinities are inconsistent. At the extreme, for the same system MS detects binding whereas NMR spectroscopy does not, suggesting a fundamental source of error. In this short essay, we will explain the reason for the observed differences and compile reliable and reproducible binding affinities. We will then highlight how a combination of MS techniques and NMR experiments affords unique insights into the process of HBGA binding by norovirus capsid proteins.

Стилі APA, Harvard, Vancouver, ISO та ін.

45

Wang, Huimei, Zhong Liu, Lanfeng Hui, Lan Ma, Xu Zheng, Jingzhi Li, and Yan Zhang. "Understanding the structural changes of lignin in poplar following steam explosion pretreatment." Holzforschung 74, no. 3 (February 25, 2020): 275–85. http://dx.doi.org/10.1515/hf-2019-0087.

Повний текст джерела

Анотація:

AbstractTo understand the modifications of lignin in the steam explosion process (209°C, 7 min), lignin samples in native poplar (LP), steam explosion solid residue (LS) and steam explosion liquid (LL) were separated and studied. The lignin samples (LP, LS and LL) were characterized and analyzed by size exclusion chromatography (SEC), Fourier transform infrared spectroscopy (FTIR), and nuclear magnetic resonance [carbon 13 numclear magnetic resonance (13C-NMR) and heteronuclear single quantum coherence or heteronuclear single quantum correlation experiment NMR (HSQC) NMR] analysis. The results revealed that the pretreatment induced reductions in amounts of β-O-4′, β-β′, and spirodienone structure, and increases in the syringyl/guaiacyl (S/G) ratio from 1.14 (LP) to 1.70 (LS) and 1.86 (LL). The HSQC NMR spectra also gave more information about the predominance of G and S units, and only small amounts of p-hydroxyphenyl (H) units. Moreover, SEC demonstrated the depolymerization and repolymerization of lignin, which were the main reasons for the increase in the average molecular weight of LS and the decrease in average molecular weight of LL, respectively. In brief, after steam explosion treatment, the lignin structure changed, but the backbone structure was not noticeably modified.

Стилі APA, Harvard, Vancouver, ISO та ін.

46

Gunawidjaja, Philips N., Renny Mathew, Andy Y. H. Lo, Isabel Izquierdo-Barba, Ana García, Daniel Arcos, María Vallet-Regí, and Mattias Edén. "Local structures of mesoporous bioactive glasses and their surface alterations in vitro : inferences from solid-state nuclear magnetic resonance." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 370, no. 1963 (March 28, 2012): 1376–99. http://dx.doi.org/10.1098/rsta.2011.0257.

Повний текст джерела

Анотація:

We review the benefits of using 29 Si and 1 H magic angle spinning (MAS) nuclear magnetic resonance (NMR) spectroscopy for probing the local structures of both bulk and surface portions of mesoporous bioactive glasses (MBGs) of the CaO–SiO 2 −(P 2 O 5 ) system. These mesoporous materials exhibit an ordered pore arrangement, and are promising candidates for improved bone and tooth implants. We discuss experimental MAS NMR results from three MBGs displaying different Ca, Si and P contents: the 29 Si NMR spectra were recorded either directly by employing radio-frequency pulses to 29 Si, or by magnetization transfers from neighbouring protons using cross polarization, thereby providing quantitative information about the silicate speciation present in the pore wall and at the MBG surface, respectively. The surface modifications were monitored for the three MBGs during their immersion in a simulated body fluid (SBF) for intervals between 30 min and one week. The results were formulated as a reaction sequence describing the interconversions between the distinct silicate species. We generally observed a depletion of Ca 2+ ions at the MBG surface, and a minor condensation of the silicate-surface network over one week of SBF soaking.

Стилі APA, Harvard, Vancouver, ISO та ін.

47

Crowe, Brandon L., Christopher J. Bohlen, Ross C. Wilson, Venkat Gopalan, and Mark P. Foster. "Assembly of the Complex between Archaeal RNase P Proteins RPP30 and Pop5." Archaea 2011 (2011): 1–12. http://dx.doi.org/10.1155/2011/891531.

Повний текст джерела

Анотація:

RNase P is a highly conserved ribonucleoprotein enzyme that represents a model complex for understanding macromolecular RNA-protein interactions. Archaeal RNase P consists of one RNA and up to five proteins (Pop5, RPP30, RPP21, RPP29, and RPP38/L7Ae). Four of these proteins function in pairs (Pop5-RPP30 and RPP21–RPP29). We have used nuclear magnetic resonance (NMR) spectroscopy and isothermal titration calorimetry (ITC) to characterize the interaction between Pop5 and RPP30 from the hyperthermophilic archaeonPyrococcus furiosus(Pfu). NMR backbone resonance assignments of free RPP30 (25 kDa) indicate that the protein is well structured in solution, with a secondary structure matching that observed in a closely related crystal structure. Chemical shift perturbations upon the addition of Pop5 (14 kDa) reveal its binding surface on RPP30. ITC experiments confirm a net 1 : 1 stoichiometry for this tight protein-protein interaction and exhibit complex isotherms, indicative of higher-order binding. Indeed, light scattering and size exclusion chromatography data reveal the complex to exist as a 78 kDa heterotetramer with two copies each of Pop5 and RPP30. These results will inform future efforts to elucidate the functional role of the Pop5-RPP30 complex in RNase P assembly and catalysis.

Стилі APA, Harvard, Vancouver, ISO та ін.

48

Islam, Md Shahidul, and Md Ashaduzzaman. "Di-Stimuli Responsive Poly(<i>N</i>-Isopropylacrylamide-co-Diethylaminoethylmethacrylate) Copolymer: Synthesis, Characterization and Investigation of Aqueous Dispersion Properties." International Letters of Chemistry, Physics and Astronomy 39 (October 2, 2014): 136–44. http://dx.doi.org/10.56431/p-l2w693.

Повний текст джерела

Анотація:

We report on the synthesis, characterization and aqueous dispersion properties of well-defined double hydrophilic copolymer with pH- and thermo-responsive segments via atom transfer radical polymerization (ATRP). Poly(N-isopropylacrylamide-co-Diethylaminoethylmeth-acrylate), P(NIPAAm-co-DEAEMA), was prepared by ATRP using methyl-4-bromomethyl benzoate initiator. The product was characterized by proton-nuclear magnetic resonance (1H NMR) and attenuated total reflectance infrared (ATR-IR) spectroscopy. The multi-responsive switching between unimer and two types of micellar aggregates were characterized by temperature-dependent dynamic light scattering (DLS). Self-assembles into two types spherical aggregates in 1 mg/mL (0.0315 mM) aqueous solution, depending on solution pH and temperatures were widely investigated. The result shows two types of aggregate with large (280 nm) aggregate and variable sizes of small (17 nm, 25 nm, 45 nm) aggregates depending on temperature ranges from 26 to 40 °C at pH 4.

Стилі APA, Harvard, Vancouver, ISO та ін.

49

Lundberg, P., N. P. Dudman, P. W. Kuchel, and D. E. Wilcken. "1H NMR determination of urinary betaine in patients with premature vascular disease and mild homocysteinemia." Clinical Chemistry 41, no. 2 (February 1, 1995): 275–83. http://dx.doi.org/10.1093/clinchem/41.2.275.

Повний текст джерела

Анотація:

Abstract Urinary N,N,N-trimethylglycine (betaine) and N,N-dimethylglycine (DMG) have been identified and quantified for clinical purposes by proton nuclear magnetic resonance (1H NMR) measurement in previous studies. We have assessed these procedures by using both one-dimensional (1-D) and 2-D NMR spectroscopy, together with pH titration of urinary extracts to help assign 1H NMR spectral peaks. The betaine calibration curve linearity was excellent (r = 0.997, P = 0.0001) over the concentration range 0.2-1.2 mmol/L, and CVs for replicate betaine analyses ranged from 7% (n = 10) at the lowest concentration to 1% (n = 9) at the highest. The detection limit for betaine was < 15 mumol/L. Urinary DMG concentrations were substantially lower than those of betaine. Urinary betaine and DMG concentrations measured by 1H NMR spectroscopy from 13 patients with premature vascular disease and 17 normal controls provided clinically pertinent data. We conclude that 1H NMR provides unique advantages as a research tool for determination of urinary betaine and DMG concentrations.

Стилі APA, Harvard, Vancouver, ISO та ін.

50

Mahmud, Iqbal, Kamal Chowdhury, and Arezue Boroujerdi. "Tissue-Specific Metabolic Profile Study of Moringa oleifera L. Using Nuclear Magnetic Resonance Spectroscopy." Plant Tissue Culture and Biotechnology 24, no. 1 (June 22, 2014): 77–86. http://dx.doi.org/10.3329/ptcb.v24i1.19214.

Повний текст джерела

Анотація:

Moringa oleifera L. an important multipurpose crop, is rich in various phytochemicals: flavonoids, antioxidants, vitamins, minerals and carotenes. The purpose of this study was to profile the groups of metabolites in leaf and stem tissues of M. oleifera. Various sugars, amino acids, and organic acid derivatives were found in all of the M. oleifera tissues with different profiles and/or peak intensities depending on the tissue. 1D proton nuclear magnetic resonance (NMR) was applied for collecting metabolite spectra. Approximately 30 metabolites with 2 unknown peaks were identified with Chenomx and verified with MMCD databases. Among these metabolites, 22 were identified as common in both leaf and stem tissues. Of the remaining 8 metabolites, 4-aminobutyrate, adenosine, guanosine, tyrosine, and p-cresol were found only in leaf tissues; however, glutamate, glutamine, and tryptophan were found only in stem tissues. Biochemical pathway analysis revealed that 28 identified metabolites were interconnected with 36 different pathways as well as related to different fatty acids and secondary metabolite-synthesis biochemical pathways. It is well known that different tissues of M. oleifera have nutritional, medicinal, and therapeutic values; therefore, our main objective is to provide a publicly available M. oliefera tissue specific metabolite database. Plant Tissue Cult. & Biotech. 24(1): 77-86, 2014 (June) D. O. I. http://dx.doi.org/10.3329/ptcb.v24i1.19214

Стилі APA, Harvard, Vancouver, ISO та ін.

Статті в журналах з теми "³¹P nuclear magnetic resonance (NMR) spectroscopy"

Оформте джерело за APA, MLA, Chicago, Harvard та іншими стилями