About the concentration dependence of the anisotropy in the magnetic susceptibility of some aromatic compounds in the liquid phase,studied by NMR

Magnetic field induced quadrupolar line splittings in the ²H NMR spectra of pyridine and metadinitrobenzene are reported. From the splittings the anisotropy in the magnetic susceptibility Δ_x has been deduced. The concentration dependence of the quadrupolar magnetic field effect, and hence of Δ_x, of nitrobenzene, metadinitrobenzene and naphthalene has been investigated. The effect of different solvents has also been studied. Environmental effects of Δ_x have been found to be substantial in several cases. The relation of the present experiments with the Cotton-Mouton effect is discussed in detail.     

Magnetic resonance studies of the deuteration effect on intersystem crossing in the anthracene molecule

The intersystem crossing decay constants from the ³B_2u state into the ground state of anthracene-d₁₀ in a phenazine crystal have been determined by magnetic resonance techniques at 1.5°K both at high magnetic field and, by a parameterization procedure, at zero magnetic field. A comparison of the anthracene-d₁₀ zero-field results with those for anthracene-h₁₀ show the effects of deuterium substitution to be largest for the in-plane spin levels of the anthracene triplet state.     

Effect of magnetic field on phase transitions in solutions of cellulose derivatives

LC transitions occurring in mixtures of cyanoethyl cellulose with DMAA or DMF and hydroxypropyl cellulose with ethanol, DMAA, or water in the presence and absence of magnetic field have been studied. With an increase in the polarity of solvent molecules and a decrease in the molecular mass of the polymer, the LC phase develops at higher concentrations and lower temperatures. Under application of magnetic field, the domain structure is formed in solutions and the temperature-concentration region of the LC phase widens. Cyanoethyl cellulose and hydroxypropyl cellulose solutions are found to possess memory: after the magnetic field is switched off, the orientation of macromolecules and the increased temperature of phase transitions are preserved for many hours. As the molecular mass of the polymer is increased, the ability of macromolecules to orient themselves in the magnetic field declines. The threshold mechanism governing the effect of magnetic field on LC transitions in polymer solutions has been discovered. The critical value of magnetic intensity that brings about a shift in boundary curves is consistent with the value of H _cr necessary for the cholesteric liquid crystal-nematic liquid crystal phase transition.     

Magnetic field induced alignment effects in 2H NMR spectra

Magnetic field induced line splittings have been recorded in the ²H NMR spectra of perdeuteropyrene and perdeuteronaphthalene dissolved in diethylether. The splittings originate from a small alignment, caused by the combined action of the anisotropic diamagnetic susceptibility χ and the magnetic field H. They are proportional to the anisotropy in χ and to H². These effects provide a new method to study this anisotropy and the influence thereon of intermolecular interactions. Since the splittings are dependent on the directions of the C–D axes relative to the principal axes of χ, they constitute a potential source of stereochemical information.     

Magnetofection: Magic magnetic nanoparticles for efficient gene delivery

Magnetic nanoparticles (MNPs) have become a research hotspot and widely used in the biomedical field in recent decades due to their unique magnetic properties. This minireview summarizes the specific gene transfection of magnetic particles (magnetofection) during eversy dynamic process of gene delivery (gene binding, cellular uptake, endosomal escape, intracellular trafficking and in vivo targeting). Meanwhile, the synergistic biomedical application of magnetofection and the effects of MNPs have also been discussed, including magnetic resonance imaging (MRI), magnetic mediated hyperthermia (MMH), Fenton reaction and autophagy. Finally, the clinical prospect of magnetofection was briefly expected.     

Measurements of K X-ray fluorescence cross sections of Fe,Co, and Ni in an external magnetic field

The effects of the external magnetic field has been investigated on the K XRF cross sections of Fe, Co, Ni, and some of their compounds by using an energy dispersive X-ray fluorescence spectrometer. The samples were irradiated by using the γ-rays of 59.537 keV emitted from an ²⁴¹Am radioisotope source of 100 mCi. The samples were prepared from pure foil of Fe, Co, Ni, and some of their compounds. The external magnetic fields have been applied two opposite directions and the magnitude of the external magnetic field has been fixed at 0.400 T and −0.400 T. The measured K XRF cross sections have been compared with the calculated theoretical data and interpolated values of Puri et al. Our experimental results show that the K XRF cross sections have been affected by the external magnetic field.     

Magnetic quenching of the emission intensities of HPO and SnH in hydrogen—oxygen flames

The effects of a magnetic field on the emission intensities of some excited species in hydrogen—oxygen flames have been studied. The emission intensities of HPO and SnH were partially quenched by an external magnetic field below 1.8 T, while those of CuH, CuCl, S₂, Se₂ and Te₂ were not changed by the field.     

Dipolar magnetic field effects in NMR spectra of liquids

Dipolar magnetic field effects have been detected in the NMR spectra of coronene and methylpyropheophorbide in liquid solution. These effects arise from the partial molecular alignment induced by the magnetic field. Both ¹H-¹H and ¹³C-¹H couplings have been detected. For both compounds the anisotropy in the diamagnetic susceptibility is calculated.     

Transient free radicals in viscous solvents

The majority of free radicals are highly reactive species which participate in bimolecular reactions with each other. Validation of the theory of molecular diffusion and reactivity in the liquid state requires knowledge of rate constants of radical–radical reactions (recombination, disproportionation) and their viscosity dependencies. An accurate comparison of theory and experiment has become available due to experimentally measured diffusion coefficients of reactive radicals by transient grating technique. Initial distribution of radicals in solution can be not random but pair-wise as in photo- or thermoinitiation of free radical polymerization reactions. Probability of a radical escape of a partner (cage escape) characterizes the initiator efficiency. Despite decades of measurement of cage effect values, cage effect dynamics with free radicals have only been investigated quite recently. The present tutorial review considers the effect of viscosity of Newtonian liquid on two types of recombination—in the solvent bulk and in a cage. Further, since radicals are paramagnetic species, external magnetic field affects probability of their reactions in pairs. These effects are also observed in viscous liquids, and reasons for such observations are explained. The recently discovered low magnetic field effect is also observed on radical pairs in viscous liquids.     

Effects of ELF Magnetic Field in Combination with Iron(III) Chloride (FeCl3) on Cellular Growth and Surface Morphology of Escherichia coli (E. coli)

This study investigated the effects of extremely low frequency (ELF) magnetic field with/without iron(III) chloride (FeCl₃) on bacterial growth and morphology. The ELF exposures were carried out using a pair of Helmholtz coil-based ELF exposure system which was designed to generate 50 Hz sinusoidal magnetic field. The field was approximately uniform throughout the axis of the coil pair. The samples which were treated or non-treated with different concentrations FeCl₃ were exposed to 50 Hz, 2 millitesla (mT) magnetic field for 24 h. ELF effect on viability was assessed in terms of viable colony counts (in colony-forming unit per milliliter) with the standard plate count technique. Scanning electron microscopy was used to investigate the magnetic field effect on surface morphology of Escherichia coli. No significant results were seen in terms of cell viability between ELF and sham-exposed bacterial strains. Similarly, FeCl₃ treatment did not change cell viability of E. coli samples. However, we observed some morphological changes on E. coli cell surfaces. Pore formations and membrane destruction were seen on the surface of 24 h ELF field-exposed cells. We concluded that ELF magnetic field exposure at 2 mT does not affect cell viability; however, it may affect bacterial surface morphology.     

Magnetic field effect on fluorescence in a mixture of N-ethylcarbazole and dimethyl terephthalate in a polymer film in the presence of electric fields

Magnetic field effects on the fluorescence spectrum and on the electrofluorescence spectrum (plots of the electric field-induced change in fluorescence intensity as a function of wavelength) have been examined in electron donor and acceptor pairs of N-ethylcarbazole (ECZ) and dimethyl terephthalate (DMTP) in polymer films at different ratios of donor/acceptor concentration. In the mixture having a high concentration of ECZ, electric field-induced quenching of the exciplex fluorescence originating from the photoinduced electron transfer becomes less efficient in the presence of a magnetic field. In the mixture having a low concentration of ECZ, on the other hand, no magnetic field effect was observed in the electrofluorescence spectrum, indicating that the hole carrier plays an important role in synergy effects of magnetic and electric field effects on exciplex fluorescence. In the absence of the applied electric field, the magnetic field does not affect either exciplex fluorescence with a peak at 450 nm or LE fluorescence emitted from the locally excited state of ECZ but enhances the broad emission with a peak at approximately 380 nm, probably assigned to the fluorescence of another type of exciplex between ECZ and DMTP. Thus, two kinds of magnetic field effects on fluorescence have been observed in a mixture of ECZ and DMTP in a polymer film.     

Magnetic effects in hydroperoxide decomposition in mixed micelles with cationic surfactants

The retardation effect of oxygen and external magnetic field on the yield of radicals in hydroperoxide decomposition in catalytic nanoreactors was discovered. Mixed reverse micelles formed by the cationic surfactants (Surf) and hydroperoxide {mLOOH...nSurf} play the role of nanoreactors. Similar effects of oxygen and external magnetic field (60–150 mT) on the yield of radicals are observed in the catalytic decomposition of hydroperoxide in the presence of acetylcholine. It is noteworthy that the retardation effect of the magnetic field decreases in the presence of paramagnetic particles such as oxygen and relatively stable radicals.     

Primary root growth rate of Zea mays seedlings grown in an alternating magnetic field of different frequencies

We have studied the effect of an alternating magnetic field on the growth rate of primary roots in Zea mays. Corn seedlings were grown in the dark, under constant conditions of temperature (25°C) and humidity (100%). They were also subjected to a 5 mT magnetic field, alternating at frequencies of either 5, 10, 20 or 40 Hz. The rate of primary root growth, in plants grown at each frequency, was measured and compared to a control group. Control plants were grown under similar conditions, in the absence of the magnetic field. The growth rate of primary roots in seedlings grown at each of the magnetic field frequencies used, was increased compared to the control group. The highest growth rate was seen in seedlings exposed to a magnetic field alternating at 10 Hz.     

Behaviour of the 3p 511s’ [1/2]1 level of Argon I in a strong magnetic field

The properties of the autoionizing 3p ⁵11s’ [1/2]₁ Argon I level have been experimentally studied in the presence of a strong magnetic field (2.14-2.22 T). Quasi- Landau type oscillations have been observed in the width and position of the 3p ⁵-4p[1/2]₀ -3p ⁵11s’ [1/2]₁ exciting transition. The results provide an additional support for earlier observations of Lemoigne et al. [7]. No evidence for similar oscillations in magnetic field dependence of the Fano q parameter was observed.     

一种用于分子发光分析的外加磁场装置

本文介绍了一种自行设计的能将外加磁场效应引入现有分子发光分析仪器的外加磁场装置，讨论了装置的组成、特点和分子发光分析法中的实际应用以及该装置在研究生命科学、生物体系磁效应等方面的潜在意义。     

Effects of an applied magnetic field on the anodic dissolution of nickel in HNO3 + Cl− solution

All types of the magnetic field effects on the anodic dissolution of metallic materials have been found in one electrochemcial system: the Ni/0.40 M HNO₃ + 5.0 mM NaCl system. The effects are similar to those of a stirring on all occasions. With the presence of the magnetic field, the current decreases in the active region. However, the current oscillations are changed to active dissolution in the prepassive region and induced in the transitive potential from the prepassive region to the passive region by the magnetic field. In the passive region, the magnetic field has little influence. Those effects are discussed with different rate-determining steps. The study of the effects of the magnetic field on this system may help us understand why the magnetic field enhances the corrosion rates in some conditions while suppressing them in others.     

Isotope substitution effects on spin dynamics of the molecular nanomagnet Fe8 cluster studied by NMR

We have carried out ¹H NMR at T=1.5 K in both ⁵⁷Fe-enriched Fe8 cluster and non-enriched Fe8 cluster to investigate isotope substitution effects on magnetic properties. The field dependence of 1/T₁ can be fitted well by using a simple model in terms of the thermal fluctuations of the total spin S=10 of the cluster originating from the spin–phonon interactions. The absence of a difference of the magnetic field dependence of 1/T₁ between the two systems indicates that the spin–phonon coupling constant is not affected by the change of mass of the isotopes in the Fe8 cluster.     

Estimation of genetic effects of a static magnetic field by a somatic cell test using mutagen-sensitive mutants of Drosophila melanogaster

In order to estimate the genetic effects of magnetic fields, a somatic cell test was performed using mutants of the fruit fly Drosophila melanogaster which lack repair functions for damage to their cellular deoxyribonucleic acid (DNA). Young larvae of mutant and normal genotypes were exposed to a homogeneuos 0.6 T magnetic field for 24 h and were then allowed to continue development under normal culture condition until they moulted and finally emerged from their pupal cases. After eclosion, the number of surviving adults was counted. The number of adults of the mutant genotype decreased by about 8% compared with unexposed controls, while that of normal siblings remained unchanged. This suggests that exposure to a static magnetic field resulted in damage to larval cellular DNA, and that somatic cells without normal DNA repair functions failed to continue cell division which resulted in developmental lethality of mutant larvae. DNA damage occurring in normal larvae should have been repaired, so that their survival rate was not altered. The effect was compared with that of UV irradiation, and the genotoxic activity of the 0.6 T static magnetic field was estimated to be the same as that of UV light with an intensity of 0.14 mJ m⁻² s⁻¹. Possible mechanisms in which DNA damage is caused by magnetic field exposure are discussed.