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Dipole-dipole operator in angular momentum basis: a complementary study in nuclear magnetic resonance.

Dipole-dipole operator in angular momentum basis: a complementary study in nuclear magnetic resonance.

DIPOLE-DIPOLE OPERATOR IN ANGULAR MOMENTUM BASIS: A COMPLEMENTARY STUDY IN NUCLEAR MAGNETIC RESONANCE. The relationship between the magnetic dipole-dipole potential energy function and its quantum analogue is presented in this work. It is assumed the reader is familiar with the classical expression of the dipolar interaction and has basic knowledge of the quantum mechanics of angular momentum. Except for these two points only elementary steps are involved.

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Pattern recognition analysis of proton nuclear magnetic resonance spectra of brain tissue extracts from rats anesthetized with propofol or isoflurane.

Pattern recognition analysis of proton nuclear magnetic resonance spectra of brain tissue extracts from rats anesthetized with propofol or isoflurane.

Methodology/Principal Findings: Rats were randomized into five groups (n = 7 each group). Propofol and isoflurane were administered to two groups each, for 2 or 6 h. The control group received no anesthesia. Brains were removed directly after anesthesia. Hydrophilic compounds were extracted from excised whole brains and measured by proton nuclear magnetic resonance spectroscopy. All spectral data were processed and analyzed by principal component analysis for comparison of the metabolite profiles. Data were visualized by plotting principal component (PC) scores. In the plots, each point represents an individual sample. The propofol and isoflurane groups were clustered separately on the plots, and this separation was especially pronounced when comparing the 6-h groups. The PC scores of the propofol group were clearly distinct from those of the control group, particularly in the 6-h group, whereas the difference in PC scores was more subtle in the isoflurane group and control groups.
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Local anesthetics: interaction with human erythrocyte membranes as studied by 1H and 31P nuclear magnetic resonance.

Local anesthetics: interaction with human erythrocyte membranes as studied by 1H and 31P nuclear magnetic resonance.

NUCLEAR MAGNETIC RESONANCE. The literature carries many theories about the mechanism of action of local anesthetics (LA). We can highlight those focusing the direct effect of LA on the sodium channel protein and the ones that consider the interaction of anesthetic molecules with the lipid membrane phase. The interaction between local anesthetics and human erythrocyte membranes has been studied by 1 H and 31 P nuclear magnetic resonance spectroscopy. It was found that lidocaine (LDC) and

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Surfactant/hydrotrope interaction in aqueous systems by nuclear magnetic resonance oxide), hydrotropy, nuclear magnetic resonance.

Surfactant/hydrotrope interaction in aqueous systems by nuclear magnetic resonance oxide), hydrotropy, nuclear magnetic resonance.

Estes deslocamentos são bastante superiores aos observados para o copolímero no processo de formação de micelas (Figura 6a) e parecem in- dicar uma interação mais efetiva entre as molécu[r]

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13C Nuclear Magnetic Resonance spectroscopy in the studies of biosythetic routes of natural products.

13C Nuclear Magnetic Resonance spectroscopy in the studies of biosythetic routes of natural products.

mais aumentadas devido ao efeito NOE (“Nuclear Overhauser Enhancement”). Como este aumento é proporcional ao número de hidrogênios ligados diretamente, os diferentes carbonos da molé- cula sofrerão diferentes variações de intensidade em virtude do NOE. Outra contribuição importante para esta distorção surge dos diferentes tempos de relaxação apresentados pelos diferentes car- bonos na molécula, levando à perda de intensidade durante o expe- rimento devido à saturação. Estas são as principais fontes de distorções que impedem a integração de espectros de RMN de 13 C
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Platinum-195 nuclear magnetic resonance of organometallic compounds.

Platinum-195 nuclear magnetic resonance of organometallic compounds.

etc, sofrem este fenômeno. Um spin nuclear se comporta como um dipolo magnético, que tende a se alinhar ao campo magné- tico aplicado. O magnetismo de um núcleo é descrito em ter- mos de sua constante giromagnética γ, que é proporcional à razão entre o momento magnético nuclear µ e o momento an- gular de spin nuclear I 2 :

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Nuclear magnetic resonance characterization of apple juice containing enzyme preparations.

Nuclear magnetic resonance characterization of apple juice containing enzyme preparations.

da β -glucose apresentou uma tendência a aumento, à medida que a concentração enzimática variou para as temperaturas de 20 e 35 ºC e diminuição para a temperatura de 50 ºC, enquanto n[r]

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J. Braz. Chem. Soc.  vol.18 número2

J. Braz. Chem. Soc. vol.18 número2

Carbonaceous pitches are used as raw materials in advanced carbon products. This work aims at combining solvent extraction methodology with low field nuclear magnetic resonance relaxometry technique in order to characterize heated-treated samples of petroleum pitches. The T 1 relaxation times showed two distinct domains: one was referring to the aromatic region and the other one was attributed to mesophase. The results also evidenced that the 1 H NMR

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Sphingolipids of the mycopathogen Sporothrix schenckii: identification of a glycosylinositol phosphorylceramide with novel core GlcNH(2)alpha 1 -> 2Ins motif

Sphingolipids of the mycopathogen Sporothrix schenckii: identification of a glycosylinositol phosphorylceramide with novel core GlcNH(2)alpha 1 -> 2Ins motif

Abbreviations : NMR, nuclear magnetic resonance; COSY, correla- tion spectroscopy ; TOCSY, total correlation spectroscopy; NOESY, nuclear Overhauser e¡ect spectroscopy; HPLC, high performance liq- uid chromatography; HPTLC, high performance thin layer chroma- tography; GC, gas chromatography; ESI, electrospray ionization; MS, mass spectrometry ; CID, collision-induced decomposition; DMSO, dimethyl sulfoxide; TMS, trimethylsilyl ; FAME, fatty acid methyl ester

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Isolation and Structural Determination of an Anti Bacterial Constituent from the Leaves of Cassia alata Linn.

Isolation and Structural Determination of an Anti Bacterial Constituent from the Leaves of Cassia alata Linn.

By different solvent extractions and chromatographic techniques an antibacterial constituent was isolated from leaves of Cassia alata Linn. Infra red spectroscopy, mass spectroscopy and nuclear magnetic resonance studies showed that the isolated compound was chemically 3,4 dihydroxy cinnamic acid. In vitro antibacterial activity of 3,4 dihydroxy cinnamic acid was studied against four Gram-positive and four Gram-negative bacteria using disc diffusion method. Minimum inhibitory concentration (MIC) of 3,4 dihydroxy cinnamic acid was also recorded against those bacteria by serial dilution technique. Kanamycin was used as positive control. Results showed that 3,4 dihydroxy cinnamic acid had antibacterial activity against the tested bacteria.
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Preparing the biodieselLCO blends

Preparing the biodieselLCO blends

The goal of the present study was to determine the potential use of thermal analysis for the measurement of the light crude oil (LCO) content of standard biodiesel mixtures. Standard samples of biodiesel/LCO blends were prepared with different ratios of biodiesel; LCO: 1:0 (biodiesel only), 1:3, 1:1, 3:1, 0:1 (LCO only). Thermogravimetry (TG) and differential scanning calorimetry were used to determine the usefulness of thermal analysis for quantification of the LCO in the mixtures. Proton nuclear magnetic resonance ( 1 H NMR) spectroscopy was also used to confirm the composition of the samples. It was found that thermogravimetric curves were
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Rev. Assoc. Med. Bras.  vol.63 número1

Rev. Assoc. Med. Bras. vol.63 número1

X-ray and computerized axial tomography of the cervi- cal spine showed lytic lesions between C2 and C3. The nuclear magnetic resonance imaging (NMR) showed signs suggestive of spondylodiscitis in C2-C3 associated with the presence of a massive epidural abscess compressing the ventral surface of the spinal cord, as well as involvement of paravertebral and prevertebral soft tissues (Figure 1). Bone scintigraphy ruled out an expansive tumor process and conirmed the NMR indings.

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J. Braz. Chem. Soc.  vol.24 número4

J. Braz. Chem. Soc. vol.24 número4

in spite of their great utility in compatibility studies, are still under used in pharmaceutical tests, like solid state nuclear magnetic resonance (ssNMR) and a special technique of thermal analysis called thermo-optical analysis (TOA). Therefore, solid state nuclear magnetic resonance, Fourier- transformed infrared spectroscopy, differential scanning

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Mycoleptones A−C and polyketides from the endophytem  indicus

Mycoleptones A−C and polyketides from the endophytem indicus

Three of the isolated metabolites are previously unreported azaphilones and were named mycoleptones A, B, and C (2, 4, and 5). Mycoleptone A (2) was isolated as a yellow powder, and the complete structural characterization was carried out by nuclear magnetic resonance (NMR) spectroscopy, high- resolution mass spectrometry (HRMS), electronic circular dichroism (ECD) spectroscopy, time-dependent density func- tional theory (TD-DFT) calculations, and single-crystal X-ray diffraction studies (Figure 2). The UV spectrum of 2 displays maximum absorptions at 254 nm (log ε 2.90) and 361 nm (log ε 2.83), revealing the presence of an extended conjugated system, characteristic of azaphilones. Compound 2 displays similar 1 H and 13 C NMR spectra to austdiol, 8,9 with the
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J. Braz. Chem. Soc.  vol.23 número11

J. Braz. Chem. Soc. vol.23 número11

A phytochemical investigation of the roots of Krameria tomentosa A. St.-Hil. led to the isolation of five neolignans, two of them with novel structures [1,1’-(E)-propenyl-4-methoxy- 3,4’-oxyneolignan (ottomentosa) and 2-(2’-hydroxy-4’,6’-dimethoxyphenyl)benzofuran- 5-carboxylic acid (sobraline)] and three known compounds [eupomatenoid 6, dihydrocarinatidin and 2-(2’,4’-dihydroxyphenyl)-5-(E)-propenylbenzofuran]. The structural characterization of the compounds isolated was established based on infrared spectroscopy, mass spectrometry, one- and two-dimensional nuclear magnetic resonance, along with comparison with spectral data described in the literature.
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Computational speed-up with a single qudit

Computational speed-up with a single qudit

parity (oddness or evenness) of a given cyclic permutation. A classical algorithm requires two que- ries to the black-box. We show that a quantum algorithm can solve the problem with a single query. Even though the problem that the algorithm solves is not crucial, the algorithm is interesting in that it makes use of a single qudit, which means that neither entanglement nor any other correlation plays a role. Moreover, we present an experimental demonstration of this algorithm using a room temperature nuclear magnetic resonance (NMR) quadrupolar setup.

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MICROCALORIMETRIC STUDY OF FUNCTIONALIZED MESOPOROUS SILICAS FOR CO2 CAPTURE UNDER DRY CONDITIONS

MICROCALORIMETRIC STUDY OF FUNCTIONALIZED MESOPOROUS SILICAS FOR CO2 CAPTURE UNDER DRY CONDITIONS

These studies have been complemented with Si 29 NMR (Nuclear Magnetic Resonance), which allows us to determine the distribution of Si-OH groups on the solid surfa[r]

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About the possibility of identification of hydrocarbon deposits with the help of NMR

About the possibility of identification of hydrocarbon deposits with the help of NMR

Abstract. The main purpose of this article is to review the theoretical prerequisites of nuclear magnetic resonance (NMR) application in tasks of search and exploration of hy- drocarbon deposits. The identification peculiarities of hydro- carbon deposits in a weak magnetic field of the Earth were analysed. The necessity of using highly directional antennas for providing greater sounding depths as well as the use of absorption spectra of the sought-for minerals as sounding signals were identified and justified. A variant of practical implementation of such a system was examined and exam- ples of practical application of the innovative NMR technol- ogy were provided.
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J. Braz. Chem. Soc.  vol.28 número10

J. Braz. Chem. Soc. vol.28 número10

A furanoditerpene-enriched fraction was obtained from the fruits of Pterodon emarginatus and submitted to semipreparative high performance liquid chromatography (HPLC). Two new furanoditerpenes, 6α,19β-diacetoxy-7β,14β-dihydroxyvouacapan and 6α-acetoxy- 7β,14β-dihydroxyvouacapan, in addition to the known compound methyl 6α-acetoxy- 7β-hydroxyvouacapan-17β-oate were obtained. Compound structures were determined by 1D and 2D nuclear magnetic resonance (NMR) experiments and electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI-FTICR-MS). The major compound methyl 6α-acetoxy-7β-hydroxyvouacapan-17β-oate was evaluated against promastigote forms of Leishmania amazonensis and L. braziliensis, presenting the concentration which causes lysis on 50% of parasites IC 50 < 30 µg mL -1 .
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