Nuclear Resonance Effect Research Articles

Probing noncovalent binding, spectroscopic characteristics and antiproliferative behavior of inclusion complex between quinoline and para-sulfonatothiacalix[4]arene

The inclusion complex between bowl-shaped para-sulfonatothiacalix[4]arene (TSCX4) macrocycle and quinoline has been studied with a unison of UV–visible, infra-red, flourescence emission and 1H nuclear magnetic resonance (NMR) and 2D nuclear overhauser effect spectroscopy (NOESY), high resolution mass spectrometry (HRMS) experiments. Both 1H NMR titration and HRMS experiments point to 1:1 stoichiometry for the water soluble Q⊂TSCX4 complex. The electronic structure of the inclusion complex obtained from density functional theory (DFT) showed a partial encapsulation of quinoline guest, which is held within the host cavity by C–H---π, π---π and hydrogen bonding interactions. The fluorescence emission spectra upon complexation display marginal blue shift of the 411 nm band in TSCX4. Moreover, the binding constant (7.1 × 103 M−1) determined from fluoresence emission experiments underline the effective host–guest binding in the complex, which was corroborated through frequency up-shift (‘blue shift’) of characteristic Ar-OH (3433 cm−1) and SO3- vibrations (1141 cm−1 and 1037 cm−1) in the measured infrared spectra of TSCX4. The antiproliferative activitities of the Q⊂TSCX4 complex against HeLA, MDA-MB-231and N2a cells are presented. The Q⊂TSCX4 complex has been shown to be efficient against N2a (neuroblastoma) cell line.

Applying Nuclear Forward Scattering as In Situ and Operando Tool for the Characterization of FeN4 Moieties in the Hydrogen Evolution Reaction.

Nuclear forward scattering (NFS) is a synchrotron-based technique relying on the recoil-free nuclear resonance effect similar to Mössbauer spectroscopy. In this work, we introduce NFS for in situ and operando measurements during electrocatalytic reactions. The technique enables faster data acquisition and better discrimination of certain iron sites in comparison to Mössbauer spectroscopy. It is directly accessible at various synchrotrons to a broad community of researchers and is applicable to multiple metal isotopes. We demonstrate the power of this technique with the hydrogen evolution mechanism of an immobilized iron porphyrin supported on carbon. Such catalysts are often considered as model systems for iron-nitrogen-carbon (FeNC) catalysts. Using in situ and operando NFS in combination with theoretical predictions of spectroscopic data enables the identification of the intermediate that is formed prior to the rate-determining step. The conclusions on the reaction mechanism can be used for future optimization of immobilized molecular catalysts and metal-nitrogen-carbon (MNC) catalysts.

The measurement of the E2 nuclear resonance effects in kaonic atoms at DAΦNE: The KAMEO proposal

KAMEO (Kaonic Atoms Measuring Nuclear Resonance Effects Ob-servables) is a proposal for an experiment aiming to perform the first consistent measurement of the E2 nuclear resonance effects in kaonic molybdenum A=94,96,98,100 isotopes. The E2 nuclear resonance mixes atomic states, due to the electrical quadrupole excitation of nuclear rotational states. It occurs in atoms having the energy of a nuclear excitation state closely matching an atomic de-excitation state energy, and affects the rates of X-ray atomic transitions matching the energy of the resonance. The measurement E2 nuclear resonance effect in KMO isotopes allows the study of the strong kaon-nucleus interaction in a rotational excited nuclear state. Moreover, the effect enables the K- to access an inner atomic level not easily reachable by the kaon normal cascade, due to the nuclear absorption. The KAMEO proposed apparatus consists of 4 enriched Mo A=94,96,98,100 isotope strips, exposed to the kaons produced by the DAφNE collider, for kaonic atoms formation, with a high-purity germanium detector, cooled with liquid nitrogen, used to measure the X-ray atomic transitions. The DAφNE collider is located at the National Laboratories of Frascati (LNF-INFN), in Italy. It is already suited for kaonic atoms measurement by the SIDDHARTA-2 collaboration.

Enzymatic and selective production of alkyl α-d-glucopyranosides by the α-glucosyl transfer enzyme derived from Xanthomonas campestris WU-9701

Several alkyl glucosides exhibit various bioactivities. 1-Octyl β-d-glucopyranoside produced by organic synthesis is used as a nonionic surfactant. However, no convenient method has been developed for the selective production of alkyl α-glucosides (α-AGs), such as 1-octyl α-d-glucopyranoside (α-OG). Therefore, we developed a simple method for selective production of α-AGs using the glucosyl transfer enzyme XgtA, (E.C. 3.2.1.20), derived from Xanthomonas campestris WU-9701. When 0.80M alkyl alcohol and 2.5 units XgtA were incubated in 2.0mL of 30mM HEPES-NaOH buffer (pH 8.0) containing 1.2M maltose at 45°C, a specific α-AG corresponding to each alkyl alcohol (C2-C10) was detected. Under the standard conditions, we examined the selective production of α-OG from 1-octanol and maltose using XgtA. The reaction product was isolated and identified as α-OG via 1H nuclear magnetic resonance and nuclear overhauser effect spectroscopy analyses. No other glucosylated products, such as maltotriose, were detected in the reaction mixture. Under the standard conditions at 45°C for 96h, 243mM α-OG (71g/L) was produced in one batch production. Moreover, the addition of glucose isomerase to the reaction mixture decreased the concentration of glucose released via the reaction and increased the amount of α-OG produced; 359mM α-OG (105g/L) was maximally produced at 96h. In conclusion, this study demonstrates the selective production of α-AGs using a simple enzymatic reaction, and XgtA has the potential to selectively produce various α-AGs.

Investigating the E2 nuclear resonance effect in kaonic atoms

The nuclear E2 resonance effect occurs when an atomic de-excitation energy is closely matched by a nuclear excitation energy. It produces an attenuation of some of the atomic X-ray lines in the resonant isotope target. Investigating the nuclear E2 resonance effect in kaonic atoms, important information about kaon-nucleus strong interaction can be provided. The only nuclear resonance effect was measured by G. L. Goldfrey, G- K. Lum and C. E. Wiegand at Lawrence Berkeley Laboratory, in 1975. The nuclear E2 resonance effect was observed in 25 hours of data taking, not enough to provide a conclusive result. In four kaonic Molybdenum isotopes (, , and ), the nuclear E2 resonance effect is expected at the same transition, with similar energy values. The KAMEO (Kaonic Atoms Measuring nuclear resonance Effects Observables) experiment plans to study the E2 nuclear resonance effect in kaonic Molybdenum isotopes at the DAΦNE e+e− collider, during the SIDDHARTA-2 experiment. The experimental strategy consists of exposing four solid strip targets, each enriched with one Molybdenum isotope, to negatively charged kaons, using a germanium detector for X-ray transition measurements. A further exposure of a non-resonant isotope solid strip target will be used as reference for standard non-resonant transitions.

Investigating the E2 Nuclear Resonance Effects in Kaonic Atoms: The KAMEO Proposal

The E2 nuclear resonance effect in kaonic atoms occurs when the energy of atomic de-excitation closely matches the energy of nuclear excitation, leading to the attenuation of some X-ray lines in the resonant isotope target. This phenomenon provides crucial information on the strong interaction between kaons and nuclei. The only nuclear E2 resonance effect observed so far was in the K− −9842Mo isotope, measured by G. L. Goldfrey, G-K. Lum, and C. E. Wiegand at Lawrence Berkeley Laboratory in 1975. However, the 25 hours of data taking were not sufficient to yield conclusive results. In four kaonic Molybdenum isotopes (9442Mo, 9642Mo, 9842and Mo, and 10042Mo), the nuclear E2 resonance effect is expected to occur at the same transition with similar energy values. To investigate this, the KAMEO (Kaonic Atoms Measuring Nuclear Resonance Effects Observables) experiment plans to conduct research on kaonic Molybdenum isotopes at the DAΦNE e+e− collider during the SIDDHARTA-2 experiment. The experimental strategy involves exposing four solid strip targets, each enriched with one Molybdenum isotope, to negatively charged kaons and using a germanium detector to measure X-ray transitions. In addition, a non-resonant 9242Mo isotope solid strip target will be used as a reference for standard non-resonant transitions.

Effect of sample age of fluorocarbons on MC800 asphaltene on dynamic nuclear polarization parameters

Nuclear Magnetic Resonance and Overhauser effect type dynamic nuclear polarization (DNP) experiments were performed to study suspensions of asphaltene in the fluorocarbons at a low magnetic field of 1.53 mT at room temperature. Asphaltene was extracted from MC800 liquid asphalt, which was Heavy Iran origin. Each sample of the solvent medium was produced at three different concentrations of asphaltene. These samples were kept for a period of seven years until DNP parameters were discovered through new DNP tests. The influence of sample age on parameters of DNP was studied and then the findings were analyzed. It was found that the  nuclear-electron coupling parameter was smaller. In low magnetic fields the nuclear-electron coupling parameter. varies from +0.5 (pure dipolar) to -1.0 (pure scalar), and new  obtained values are between these limits. New  values in our study are positive and this shows that the dipolar part of intermolecular spin-spin interactions is dominant.

Structural characterization of methyl-β-cyclodextrins by high-performance liquid chromatography and nuclear magnetic resonance spectroscopy and effect of their isomeric composition on the capillary electrophoresis enantioseparation of daclatasvir

The separation of daclatasvir and its R,R,R,R-enantiomer was studied by capillary electrophoresis using various randomly methylated β-CDs and the single isomer heptakis(2,6-di-O-methyl)-β-CD (2,6-DM-β-CD) as chiral selectors in an acidic background electrolyte. Opposite enantiomer migration order was observed for randomly substituted CDs compared to 2,6-DM-β-CD as well as methylated β-CDs with different composition according to the specifications of the manufacturers. HPLC and NMR analyses confirmed that the presence of a high 2,6-DM-β-CD content in the CDs enables to achieve the migration order R,R,R,R-enantiomer > daclatasvir. In contrast, products with low 2,6-DM-β-CD isomer content and/or the presence of a large amount of methylated CD isomers, in which d-glucopyranose moieties are not substituted in either position 2 or 6, displayed the opposite enantiomer migration order daclatasvir > R,R,R,R-enantiomer. The study indicated the importance of the type and composition of derivatized CDs on chiral separations in capillary electrophoresis as well as the importance of proper quality control for cyclodextrin manufacturers. Moreover, the observed migration order could be rationalized based on the composition and substitution pattern of the CDs.

Photostability of the inclusion complex of isoamyl4-(Dimethylamino)benzoate with sulfobutylether-β-cyclodextrin

The inclusion complex of isoamyl 4-(Dimethylamino)benzoate (IDB) with sulfobutylether-β-cyclodextrin (SBE-β-CD) was prepared by freeze-drying method. The Benesi-Hildebrand method and Job’s plot showed that the IDB formed 1:2 stoichiometric inclusion complex with SBE-β-CD. The inclusion complex of SBE-β-CD with IDB was characterized by X-ray powder diffractometry (XRD), thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC), scanning electron microscopy (SEM), nuclear magnetic resonance (1H NMR) and two-dimensional rotational frame Overhauser effect spectroscopy (2D ROESY). The results of 1H NMR and 2D ROESY spectra showed that the hydrophobic group of IDB associated with SBE-β-CD from the wide and narrow side. The solubility and thermal stability of IDB were both improved after formed the inclusion complex. The photodegradation experiment showed that the photolysis ratio of IDB decreased from 9.16% to 2.25% due to the complexation of SBE-β-CD. It could be the potential way to promote its cosmetic application in UVB sunscreen.

The Choice of Criteria and Methods to Estimate the Quality of the Angular Sensor Based on the Effect of Nuclear Magnetic Resonance

To adjust the stabilization systems that ensure the operation of the angular position or rate sensor based on the effect of nuclear magnetic resonance, it is required to choose the criteria for the quality assessing of sensor’s operation. The article presents the criteria of the quality of the angular sensor operating as a self-oscillation system. It is shown that the accuracy of the angular sensor increases when the proposed criteria are met.

Preparation, characterization and biological evaluation of β-cyclodextrin-biotin conjugate based podophyllotoxin complex

Podophyllotoxin is a natural occurring aryltetralin lignin with pronounced cytotoxic activity. However, its clinical application for cancer treatment has been blocked due to its poor water solubility and selectivity. In this work, biotin as a tumor specific ligand was coupled with β-cyclodextrin and the resulting biotin modified β-cyclodextrin was used to complex with podophyllotoxin to improve its aqueous solubility and tumor selectivity. The solubility of β-cyclodextrin was greatly enhanced(>16 times) by conjugating with biotin. podophyllotoxin/ mono-6-biotin-amino-6-deoxy-β-cyclodextrin inclusion complex was prepared by freeze-drying method and the complex behavior between mono-6-biotin-amino-6-deoxy-β-cyclodextrin and podophyllotoxin was studied by water solubility, phase solubility, Job's plot, UV spectroscopy, Proton Nuclear Magnetic Resonance, Rotating-frame Overhauser Effect Spectroscopy, Powder X-ray diffraction and Scanning electron microscopy. The solubility of podophyllotoxin/ mono-6-biotin-amino-6-deoxy-β-cyclodextrin complex was greatly improved(9 times) compared with Podophyllotoxin. The stability constant of podophyllotoxin/ mono-6-biotin-amino-6-deoxy-β-cyclodextrin complex (Ks= 415.29 M−1) was 3.2 times that of podophyllotoxin/β-cyclodextrin complex. The possible inclusion mode of podophyllotoxin/mono-6-biotin-amino-6-deoxy-β-cyclodextrin complex was inferred from the Proton Nuclear Magnetic Resonance and Rotating-frame Overhauser Effect Spectroscopy. The cellular uptake study showed that the introduction of biotin increased the cellular uptake of rhodamine-B/mono-6-biotin-amino-6-deoxy-β-cyclodextrin complex. Moreover, cell cytotoxicity study showed that the antitumor activity of podophyllotoxin/ mono-6-biotin-amino-6-deoxy-β-cyclodextrin complex was more potent than podophyllotoxin/β-cyclodextrin complex and free podophyllotoxin. The superior water solubility and enhanced cytotoxicity suggested that the mono-6-biotin-amino-6-deoxy-β-cyclodextrin associated inclusion complex might be a potential and promising delivery system for hydrophobic chemotherapeutics such as podophyllotoxin.

Membrane Topology of an Ion Channel Detected by Solid-State Nuclear Magnetic Resonance and Paramagnetic Effects.

Ion channels are often targeted by toxins or other ligands to modify their channel activities and alter ion conductance. Interactions between toxins and ion channels could result in changes in membrane insertion depth for residues close to the binding site. Paramagnetic solid-state nuclear magnetic resonance (SSNMR) has shown great potential in providing structural information on membrane samples. We used KcsA as a model ion channel to investigate how the paramagnetic effects of Mn2+ and Dy3+ ions with headgroup-modified chelator lipids would influence the SSNMR signals of membrane proteins in proteoliposomes. Spectral comparisons have shown significant changes of peak intensities for the residues in the loop or terminal regions due to paramagnetic effects corresponding to the close proximity to the membrane surface. Hence, these results demonstrate that paramagnetic SSNMR can be used to detect surface residues based on the topology and membrane insertion properties for integral membrane proteins.

Understanding the role of dye in colorful thermoplastic film under visible light

Polystyrene is a thermoplastic that is widely used in industry to manufacture of various materials. In this work, the objective was to investigate the effect of the Crystal Violet (CV) dye on polystyrene films under visible light. The films were produced by the casting method. Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), and viscosimetry were used to monitor the effect of radiation and 1H Nuclear Magnetic Resonance (1H-NMR) was employed to evaluate the interaction between the polymer and the dye. Carbonyl Index confirmed that oxygenated species were formed during exposure to light and photo-oxidation is the major mechanism involved in CV-sensitized PS degradation. The variations in relaxation times indicated that electrostatic attraction is the main form of interaction between the materials involved and molecular dynamics calculations confirm the 1H-NMR results. The CV dye could initiate degradation reactions and acted as an efficient photosensitizer in PS matrices.

Analysis of the Diagnostic Effect of CT and Nuclear Magnetic Resonance in Lacunar Infarction

Analysis of the Diagnostic Effect of CT and Nuclear Magnetic Resonance in Lacunar Infarction

Spin dynamics of a hydrogen atom in a periodic magnetic structure

The spin dynamics of a hydrogen atom during the passage of a periodic magnetic structure is discussed. The occupation numbers of the components of the hyperfine structure are considered as a function of time. The characteristic low-frequency oscillations are visible, which have a direct analogue in the effect of nuclear magnetic resonance. An envelope forms of these oscillations are found using the Krylov–Bogolyubov–Mitropol’skii method. The dependence of spin dynamics on the parameters of the magnetic structure is investigated. It is shown that this dependence is very sensitive to the structure of the magnetic field.

NMR spectroscopy for assessing cocaine-functional monomer interactions when preparing molecularly imprinted polymers

Synthesis of molecularly imprinted polymers (MIPs) implies a previous pre-polymerization stage in which the template (the molecule for which the MIP offers the specific recognition cavities) interacts with the adequate functional monomer, just before the addition of the cross-linker and the initiator for performing the polymerization synthesis. The recognition properties, as well as the physical properties of the prepared MIP beads, are dependent on the successful template-monomer interaction during the pre-polymerization stage. Investigations by proton nuclear magnetic resonance (1H NMR) and nuclear overhauser effect (NOE) were performed to study the interactions between the template (cocaine) and the monomers (methacrylic acid and ethylene dimethacrylate). Experimental results were additionally compared to those obtained by in silico studies.

IT in development of express method for consumer goods quality control

Implementation of IT significantly increases opportunities of the leading operators on the commodity market in the sphere of efficient quality and safety monitoring throughout the food products life cycle. Development of the compact analytical equipment for control of physical and chemical parameters regulated by the applicable technical standards at production, storage and marketing of food products is the important task having social implication. Represented in the article as an IT application solution is the express method for determination of casein concentration in dairy products packed with the help of the units using nuclear magnetic resonance (NMR) effect. With the aid of this express method the adulterated dairy products (milk, condensed milk, curd, etc.) can be revealed which are produced on the basis of dry skimmed milk containing a dry milk serum by substitution of the milk protein — casein. According to the preliminary assessment the minimum concentration of casein reported by such method is approx. 0.5%. The method is based on investigation of the hydration process of casein micelles participating in formation of structural-mechanical properties of protein coagula created at fermented milk products generation.

Studies on the preparation and photostability of avobenzone and (2-hydroxy)propyl-β-cyclodextrin inclusion complex

The inclusion complex of avobenzone and (2-hydroxy)propyl-β-cyclodextrin (2-HP-β-CD) was prepared successfully. The effects of the inclusion behavior of avobenzone with 2-HP-β-CD were investigated in both solution and the solid state with the following methods: UV–vis spectrophotometry (UV–vis), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TG), differential scanning calorimetry (DSC), and scanning electron microscopy (SEM), proton nuclear magnetic resonance (1H-NMR) and two-dimensional rotational frame nuclear overhauser effect spectroscopy (2D ROESY). The photostability of avobenzone and its inclusion complex were both investigated by UV–vis spectrophotometry. The Benesi-Hildebrand’s method showed that avobenzone formed 1:2 stoichiometric inclusion complex with 2-HP-β-CD. The solubility, thermal stability and the photostability of avobenzone were all improved after encapsulating by the 2-HP-β-CD. Therefore, it can be a potentially promising way to promote its cosmetic preparations in UVA sunscreen.

Identification of molecular-interaction sites between lowly hydrolyzed polyvinyl alcohols and indomethacin by NMR spectroscopy

To evaluate the potency of hydrolyzed polyvinyl alcohols (PVAs) as matrices for solid dispersion (SD) formulations, we examined their inhibitory effects on precipitation of a poorly water-soluble drug, indomethacin (IND). Additionally, to clarify their mechanism, we investigated the intermolecular interaction of IND with PVAs in the supersaturated aqueous solution of IND. In the present study, we used five kinds of PVAs, i.e. JR-05 (70.0–74.0% hydrolyzed), JL-05E (80.0–84.0% hydrolyzed), JP-05 (87.0–89.0% hydrolyzed), JT-05 (93.5–94.5% hydrolyzed) and JF-05 (98.0–99.0% hydrolyzed). Of various PVAs, the lowly hydrolyzed PVAs such as JR-05 and JL-05E dramatically inhibited the precipitate formation of IND. Interestingly, the lowly hydrolyzed PVAs possessed micelle-forming ability, and inhibited the nucleation and crystal growth of IND. Moreover, strong hydrophobic interactions between vinyl acetate unit of lowly hydrolyzed PVA and hydrophobic moiety of IND were suggested based on the results of nuclear magnetic resonance (1H NMR) and nuclear overhauser effect spectroscopy (NOESY) in deuterium oxide. To the best of our knowledge, this is the first report describing the inhibitory effects of the hydrolyzed degree of PVAs on the precipitation of a drug, and demonstrating the intermolecular interaction between PVAs and a drug using NOESY in water.

Structure of a new usnic acid derivative from a deacylating Mannich reaction: NMR studies supported by theoretical calculations of chemical shifts.

In a conventional Mannich reaction using piperidine, hydroxypiperidines, morpholine, and N-methylpiperazine with usnic acid, a deacetylation was observed resulting in a substitution at C-2, a loss of an acetyl group, and a Mannich base with a stabilized enol. The enol has a hydrogen bond to the nitrogen of the secondary amine. The structure was investigated by nuclear magnetic resonance and deuterium isotope effects on 13 C chemical shifts as well as with density functional theory calculations to study the changed hydrogen bond pattern. It was found that the hydrogen bond involving the OH-9 group in chloroform forms a strong hydrogen bond than in usnic acid itself and that this hydrogen bond becomes even stronger in the more polar solvent, dimethylsulfoxide. Tautomerism was observed in the Mannich base as demonstrated by deuterium isotope effects on chemical shifts. The position of the tautomeric equilibrium depends on the solvent, and the position of the equilibrium governs the strength of the OH-9…O═C hydrogen bond.