Changes in neurite outgrowth but not in cell division induced by low EMF exposure: influence of field strength and culture conditions on responses in rat PC12 pheochromocytoma cells

The effects of low electromagnetic field (EMF) exposure (4.5-15.8 microT, 50 Hz AC) on neurite outgrowth and cell division in rat PC12 pheochromocytoma cells were examined. The study involved two separate experimental series in which culture conditions during exposure to the magnetic fields differed. In series 1 (14 experiments in which culture conditions were not strongly conducive to cell differentiation [15% serum]), exposure to 4.5-8.25 microT for 23 h significantly inhibited neurite outgrowth by 21.5 +/- 1.3% (by Manova, p = 0.003). In contrast, in series 2 (12 experiments in which culture conditions promoted cellular differentiation [4% serum]), exposure to 4.35-8.25 microT for 23 h significantly stimulated neurite outgrowth by 16.9 +/- 1.1% (by Manova, p = 0.009). Thus, in both series, exposure to a narrow range of low EMF has significant, but opposite effects on neurite outgrowth. Exposure to higher fields, 8.25-12.5 microT (series 1) and 8.25-15.8 microT (series 2) had no significant effect on neurite outgrowth. These data, when considered with other reports, suggest that neuronal differentiation can be altered by low level EMF exposure. While this may not be detrimental, it merits further research. At present, the reasons for the significant changes in neurite outgrowth being confined to the same narrow field strength are unclear. As stated above, culture conditions in series 2 were more conducive to cell differentiation than those in series 1. This is reflected in the lower number of cells in control samples in series 2, at the end of the 23-h incubation, than in series 1 (- 16.9 +/- 1.7%, p = 0.003). As the same numbers were plated in both series, the medium used in series 1 allows more of the PC12 cells to divide; this is consistent with some cells reverting to a non-neuronal adrenal chromaffin phenotype [L. Greene, A. Tischler. Establishment of a noradrenergic clonal line of rat adrenal pheochromocytoma cells which respond to nerve growth factor. Proc. Natl. Acad. Sci. U. S. A., 73 (1976) 2424-2426]. Exposure to both ranges of magnetic fields (4.35-8.25 and 8.25-15.8 microT) has no effect on cell division. Thus, there is no evidence in this study that there is a mitogenic effect arising from low EMF exposure.     

Thresholds for electromagnetic field-induced hypoxia protection: evidence for a primary electric field effect

We have recently reported that weak electromagnetic (EM) field exposure of chick embryos induces a response that can be used to protect against subsequent hypoxic insult. This work is continued here with an exposure response study using 20-min exposure to 60 Hz magnetic fields over a range of 2-10 microT. Once again, the biomarker used was induction of hypoxia protection. A sigmoidal response curve was found, with exposures to magnetic field strengths > or = 4 microT inducing maximum hypoxia protection (68% survival). We also attempted to determine whether the magnetic or induced electric component of the EM field was responsible for the observed protection. This was accomplished by making measurements with two different orientations of the magnetic fields (perpendicular and parallel to the major axis of the egg). Owing to the configuration of the embryo in the egg, the induced electric field at the embryo was lower when the magnetic field was parallel to the major axis even though the magnetic field strength was the same for each orientation. Exposure of the embryos to the parallel orientation resulted in a reduced protective response. An exposure-response curve generated for this orientation of the field also showed a more "drawn-out" appearance, consistent with the observed distribution of embryo positions within the egg. Our results suggest that the induced electric, not the applied magnetic field, plays a primary role in the protective effect observed in this chick embryo model.     

Synthesis and magnetic properties of an amine-templated Fe2+ (s = 2) sulfate with a distorted Kagome structure

An organically templated iron(II) sulfate of the composition [H3N(CH2)2NH2(CH2)2(NH3]4[Fe(II)9F18(SO4)6].9H2O with a distorted Kagome structure has been synthesized under solvothermal conditions in the presence of diethylenetriamine. The distortion of the hexagonal bronze structure comes from the presence of two different types of connectivity between the FeF4O2 octahedra and the sulfate tetrahedra. This compound exhibits magnetic properties different from those of an Fe(II) compound with a perfect Kagome structure and is a canted antiferromagnet at low temperatures.     

Hydrogen adsorption strength and sites in the metal organic framework MOF5: Comparing experiment and model calculations

Hydrogen adsorption in porous, high surface area, and stable metal organic frameworks (MOF’s) appears a novel route towards hydrogen storage materials [N.L. Rosi, J. Eckert, M. Eddaoudi, D.T. Vodak, J. Kim, M. O’Keeffe, O.M. Yaghi, Science 300 (2003) 1127; J.L.C. Rowsell, A.R. Millward, K. Sung Park, O.M. Yaghi, J. Am. Chem. Soc. 126 (2004) 5666; G. Ferey, M. Latroche, C. Serre, F. Millange, T. Loiseau, A. Percheron-Guegan, Chem. Commun. (2003) 2976; T. Loiseau, C. Serre, C. Huguenard, G. Fink, F. Taulelle, M. Henry, T. Bataille, G. Férey, Chem. Eur. J. 10 (2004) 1373]. A prerequisite for such materials is sufficient adsorption interaction strength for hydrogen adsorbed on the adsorption sites of the material because this facilitates successful operation under moderate temperature and pressure conditions. Here we report detailed information on the geometry of the hydrogen adsorption sites, based on the analysis of inelastic neutron spectroscopy (INS). The adsorption energies for the metal organic framework MOF5 equal about 800 K for part of the different sites, which is significantly higher than for nanoporous carbon materials (550 K) [H.G. Schimmel, G.J. Kearley, M.G. Nijkamp, C.T. Visser, K.P. de Jong, F.M. Mulder, Chem. Eur. J. 9 (2003) 4764], and is in agreement with what is found in first principles calculations [T. Sagara, J. Klassen, E. Ganz, J. Chem. Phys. 121 (2004) 12543; F.M. Mulder, T.J. Dingemans, M. Wagemaker, G.J. Kearley, Chem. Phys. 317 (2005) 113]. Assignments of the INS spectra is realized using comparison with independently published model calculations [F.M. Mulder, T.J. Dingemans, M. Wagemaker, G.J. Kearley, Chem. Phys. 317 (2005) 113] and structural data [T. Yildirim, M.R. Hartman, Phys. Rev. Lett. 95 (2005) 215504].     

High-spin Mn wheels

The syntheses, structures, and magnetic properties of the complexes [MnIV4MnIII10MnII2O2(OCH3)12(tmp)8(O2CCH3)10].3Et2O (1.3Et2O), [MnIV2MnIII18MnII2O6(OCH3)14(O2CCH3)16(tmp)8(HIm)2].2CH3OH (2.2CH3OH), and [MnIV2MnIII18MnII2O6(OCH3)14(O2CCH3)16(Br-mp)8(HIm)2].2C6H14.5CH3OH (3.2C6H14.5CH3OH) are reported. The unusual wheel-like complexes were prepared by the treatment of [Mn3O(O2CCH3)6(HIm)3](O2CCH3) (HIm = imidazole) with 1,1,1-tris-(hydroxymethyl)propane (H3tmp) (1 and 2) or 2-(bromomethyl)-2-(hydroxymethyl)-1,3-propanediol (Br-mpH3) (3) in the presence of sodium methoxide (NaOCH3, 2, and 3) in CH3OH. Complex 1.3Et2O crystallizes in the triclinic space group P, while complexes 2.2CH3OH and 3.2C6H14.5CH3OH crystallize in the orthorhombic space group Pbca. Direct current magnetic susceptibility data, collected for 1-3 in the respective 1.8-300 K and 0.1-7 T temperature and magnetic-field ranges, afford spin ground-state values of S = 14 +/- 1 for complex 1 and S = 9 +/- 1 for complexes 2 and 3. Alternating current susceptibility measurements performed on all three complexes in the 1.8-10 K temperature range in a 3.5 G oscillating field at frequencies between 50 and 1000 Hz reveal out-of-phase chi"M signals below approximately 3 K. Single-crystal hysteresis loop and relaxation measurements confirm single-molecule magnetism behavior.     

An iron(III) phosphonate cluster containing a nonanuclear ring

This communication reports the first example of cyclic ferric clusters with an odd number of iron atoms capped by phosphonate ligands, namely, [Fe9(mu-OH)(7)(mu-O)2(O3PC6H9)8(py)12]. The magnetic studies support a S = 1/2 ground state with an exchange coupling constant of about J approximately equal to -30 K.     

Change in broth culture is associated with significant suppression of Escherichia coli death under high magnetic field

When Escherichia coli B was cultivated under an inhomogeneous magnetic field of 5.2-6.1 T, a significant 100,000-fold suppression of cell death was observed [Bioelectrochemistry 53 (2001) 149]. The limited magnetic field exposure for 12 h after logarithmic growth phase was sufficient to observe similar suppressive effects on cell death [Bioelectrochemistry 54 (2001) 101]. These results suggest some possible changes in either the medium or the cells during the magnetic field exposure. When the cell-free filtrate of the broth cultured under the magnetic field for 10 h and the cells of E. coli cultivated under the geomagnetic field for 30 h were mixed, and the mixture was subsequently cultivated under the geomagnetic field, the number of cells observed in the filtrate exposed to the high magnetic field was 20,000 times higher than that in the filtrate exposed to the geomagnetic field. When the cells cultivated under the magnetic field for 10 h and the cell-free filtrate of the broth culture exposed to the geomagnetic field were mixed, only a 50-fold difference in the number of cell between under the magnetic field and under the geomagnetic field was observed. This suggests that the filtrate of the broth culture exposed to the magnetic field is primarily responsible for the cell death suppression. It was also revealed that the small difference in pH of the filtrates of the broth culture between under the magnetic field and under the geomagnetic field was critical for the cell death suppression.     

Low-frequency magnetic field effect on cytoskeleton and chromatin

The effect of magnetic fields on the living systems is studied in vivo or in vitro in very broad spectrum of organisms, cells and tissues. The mechanism of their acting is not known until now. We studied low-frequency magnetic field effect on cytoskeleton and on the structure of chromatin in human cells. We used cell line of small lung carcinoma (A549) and the effects of magnetic field on cytoskeleton and higher-order chromatin structure were analyzed 96 h of magnetic field exposure. Magnetic field generated by the cylindrical soil was homogenous and the cells were cultivated at 37 degrees C in humidified atmosphere containing 5% CO(2). Magnetic field induction was B(m)=2 mT and the net frequency f=50 Hz. In such affected and control cells the F-actin was estimated using FITC-conjugated Phalloidin and mitochondria were studied using MitoTracker (Molecular Probes). Images of cytoskeleton and genetic loci were acquired using confocal microscopy and analysis was performed by FISH 2.0 software. Slight morphological changes of F-actin filaments and mitochondria were observed in affected cells and nuclear condensation was found. These effects could be related to the process of cell death apoptosis probably induced by magnetic field. The studies aimed at centromeric heterochromatin (9cen) did not show statistically significant changes. Therefore, we suggest that magnetic field has no influence on higher order chromatin structure but certain changes could be observed on the level of cytoskeleton. However, these statements need a thorough verification. Our preliminary experiments will be extended and the effect of magnetic field on another structures of cytoskeleton and cell nuclei will be further studied.     

The indirect through-space F-F coupling in peri-difluoronaphthalene: is it anisotropic?

The (1)H, (19)F and (13)C spectra have been obtained of a sample of peri-difluoronaphthalene dissolved in the nematic liquid crystalline solvent ZLI 1695. The (13)C satellite spectra from the six, single-(13)C isotopomers at natural abundance in both the (1)H and (19)F spectra were identified and analysed to yield a set of residual total, anisotropic spin-spin couplings, T(ij). This was achieved by first obtaining residual (13)C-(19)F and (13)C-(1)H couplings from a proton-encoded, (13)C detected, local field 2D spectrum. The 45 values of T(HH), T(HF) and T(CH) were used to obtain the structure of the molecule, and then to estimate whether there is a significant contribution from the component along the magnetic field, J, of the anisotropic, electron-mediated, spin-spin coupling tensors for (13)C-(19)F and (19)F-(19)F pairs. It is found that there is strong evidence for a significant contribution of J to T(FF) but not for the (13)C-(19)F pairs.     

Electronic spectra and crystal field analysis of energy levels of Ho3+ in HoF6(3-)

The electronic absorption spectra of single crystals of Cs(2)NaHoF(6) have been recorded in the spectral region between 4700 and 42000 cm(-1) at temperatures down to 10 K. The structure in the (5)I(8) → (5)I(J) (J = 7-4), (5)F(J) (J = 5-1), (5)S(2), (5)G(J) (J = 4-6), (3)K(J) (J = 7, 8) transitions has been analyzed and assigned. The emission spectra (5)S(2) → (5)I(J) (J = 6-8) and (5)G(4) → (5)I(J) (J = 5-7), (5)F(5) have also been recorded at 10 K for crystals of Cs(2)NaHoF(6) and partly also for samples of Cs(2)NaHoF(6):Yb(3+). The spectra comprise magnetic dipole zero phonon lines and electric dipole allowed one-phonon vibronic sidebands. From the detailed interpretation of the emission and absorption spectra, aided by a clear understanding of the vibrational behavior of the HoF(6)(3-) moiety and by magnetic dipole intensity calculations, a data set of 59 energy levels spanning 17 multiplet terms was derived. Crystal field calculations were then performed using a 4f(10) basis, as well as including the configuration interaction with a p-electron configuration. The latter calculation, which employed 14 parameters, gave better agreement with experiment and the mean deviation was 13.5 cm(-1). A comparison with the energy level fittings for Cs(2)NaHoCl(6) has been included. The crystal field parameters for the fluoro- and chloro-systems followed empirically predicted ratios.     

Unusual long-range spin-spin coupling in fluorinated polyenes: a mechanistic analysis

Nuclear magnetic resonance (NMR) is a prospective means to realize quantum computers. The performance of a NMR quantum computer depends sensitively on the properties of the NMR-active molecule used, where one requirement is a large indirect spin-spin coupling over large distances. F-F spin-spin coupling constants (SSCCs) for fluorinated polyenes F-(CH==CH)n-F (n=1cdots, three dots, centered5) are >9 Hz across distances of more than 10 A. Analysis of the F,F spin-spin coupling mechanism with our recently developed decomposition of J into Orbital Contributions with the help of Orbital Currents and Partial Spin Polarization (J-OCOC-PSP=J-OC-PSP) method reveals that coupling is dominated by the spin-dipole (SD) term due to an interplay between the pi lone-pair orbitals at the F atoms and the pi(C2n) electron system. From our investigations we conclude that SD-dominated SSCCs should occur commonly in molecules with a contiguous pi-electron system between the two coupling nuclei and that a large SD coupling generally is the most prospective way to provide large long-range spin-spin coupling. Our results give guidelines for the design of suitable active molecules for NMR quantum computers.     

Shock tube investigation of CH3 + CH3OCH3

The title reaction has been investigated in a diaphragmless shock tube by laser schlieren densitometry over the temperature range 1163-1629 K and pressures of 60, 120, and 240 Torr. Methyl radicals were produced by dissociation of 2,3-butanedione in the presence of an excess of dimethyl ether. Rate coefficients for CH(3) + CH(3)OCH(3) were obtained from simulations of the experimental data yielding the following expression which is valid over the range 1100-1700 K: k = (10.19 ± 3.0)T(3.78)?exp((-4878/T)) cm(3) mol(-1)s(-1). The experimental results are in good agreement with estimates by Curran and co-workers [Fischer, S. L.; Dryer, F. L.; Curran, H. J. Int. J. Chem. Kinet.2000, 32 (12), 713-740. Curran, H. J.; Fischer, S. L.; Dryer, F. L. Int. J. Chem. Kinet.2000, 32 (12), 741-759] but about a factor of 2.6 lower than those of Zhao et al. [Zhao, Z.; Chaos, M.; Kazakov, A.; Dryer, F. L. Int. J. Chem. Kinet.2008, 40 (1), 1-18].     

19F high magnetic field NMR study of beta-ZrF4 and CeF4: from spectra reconstruction to correlation between fluorine sites and 19F isotropic chemical shifts

High magnetic field and high spinning frequency one- and two-dimensional one-pulse MAS 19F NMR spectra of beta-ZrF4 and CeF4 were recorded and reconstructed allowing the accurate determination of the 19F chemical shift tensor parameters for the seven different crystallographic fluorine sites of each compound. The attributions of the NMR resonances are performed using the superposition model for 19F isotropic chemical shift calculation initially proposed by Bureau et al. (Bureau, B.; Silly, G.; Emery, J.; Buzaré, J.-Y. Chem. Phys. 1999, 249, 85-104). A satisfactory reliability is reached with a root-mean-square (rms) deviation between calculated and measured isotropic chemical shift values equal to 1.5 and 3.5 ppm for beta-ZrF4 and CeF4, respectively.     

(CH3)4N][(C5H5NH)0.8((CH3)3NH)0.2]U2Si9O23F4 (USH-8): an organically templated open-framework uranium silicate

The open-framework uranium fluorosilicate [(CH3)4N][(C5H5NH)0.8((CH3)3NH)0.2]U2Si9O23F4 (USH-8) has been synthesized hydrothermally by using tetramethylammonium hydroxide and pyridine-HF. The compound has a framework composition U2Si9O23F4 based on silicate double layers that are linked by chains of UO3F4 pentagonal bipyramids. The framework has 12-ring channels along [010] and 7-ring channels along [100]. The [010] 12-ring channels have a calabash-shape with the middle part partially blocked by the uranyl oxygen atoms. The narrow side of the 12-ring channels is occupied by well-ordered TMA cations while the wide side is occupied by disordered pyridinium and trimethylammonium cations.     

Atmospheric chemistry of 4:2 fluorotelomer alcohol (n-C4F9CH2CH2OH): products and mechanism of Cl atom initiated oxidation in the presence of NOx

Smog chamber/FTIR techniques were used to study the Cl atom initiated oxidation of 4:2 fluorotelomer alcohol (C(4)F(9)CH(2)CH(2)OH, 4:2 FTOH) in the presence of NO(x) in 700 Torr of N(2)/O(2) diluent at 296 K. Chemical activation effects play an important role in the atmospheric chemistry of the peroxy, and possibly the alkoxy, radicals derived from 4:2 FTOH. Cl atoms react with C(4)F(9)CH(2)CH(2)OH to give C(4)F(9)CH(2)C(*)HOH radicals which add O(2) to give chemically activated alpha-hydroxyperoxy radicals, [C(4)F(9)CH(2)C(OO(*))HOH]*. In 700 Torr of N(2)/O(2) at 296 K, approximately 50% of the [C(4)F(9)CH(2)C(OO(*))HOH]* radicals decompose "promptly" to give HO(2) radicals and C(4)F(9)CH(2)CHO, the remaining [C(4)F(9)CH(2)C(OO(*))HOH]* radicals undergo collisional deactivation to give thermalized peroxy radicals, C(4)F(9)CH(2)C(OO(*))HOH. Decomposition to HO(2) and C(4)F(9)CH(2)CHO is the dominant atmospheric fate of the thermalized peroxy radicals. In the presence of excess NO, the thermalized peroxy radicals react to give C(4)F(9)CH(2)C(O(*))HOH radicals which then decompose at a rate >2.5 x 10(6) s(-1) to give HC(O)OH and the alkyl radical C(4)F(9)CH(2)(*). The primary products of 4:2 FTOH oxidation in the presence of excess NO(x) are C(4)F(9)CH(2)CHO, C(4)F(9)CHO, and HCOOH. Secondary products include C(4)F(9)CH(2)C(O)O(2)NO(2), C(4)F(9)C(O)O(2)NO(2), and COF(2). In contrast to experiments conducted in the absence of NO(x), there was no evidence (<2% yield) for the formation of the perfluorinated acid C(4)F(9)C(O)OH. The results are discussed with regard to the atmospheric chemistry of fluorotelomer alcohols.     

Ferromagnetic exchange interactions for Cu6(12+) and Mn6(12+) hexagons sandwiched by two B-alpha-[XW9O33]9- (X = As(III) and Sb(III)) ligands in D3d-symmetric polyoxotungstates

Two novel Cu6 and Mn6 hexagon sandwiched polyoxometalates, [(CuCl)6(AsW9O33)2]12- (1a) and [(MnCl)6(SbW9O33)2]12- (2a), have been synthesized and characterized by X-ray single-crystal analysis and magnetic measurements. These complexes are D3d symmetric and were isolated as [n-BuNH3]+ salts from aqueous solutions: (n-BuNH3)12[(CuCl)6(AsW9O33)2].6H2O (1), rhombohedral, R, a = 20.33(1) A, c = 26.35(2) A, Z = 3 and (n-BuNH3)12[(MnCl)6(SbW9O33)2].6H2O (2). Six Cu (or Mn) atoms, each of which shows 5-fold coordination, make an approximately equatorial hexagon with a first-neighboring Cu...Cu (Mn...Mn) distance of 2.913(2) A (3.248(1) A) and a Cu-O-Cu (Mn-O-Mn) bond angle of 94.5(2) degrees (100.4(2) degrees ). The magnetic behavior investigated by magnetic susceptibility measurements shows the ferromagnetic exchange interactions with J/k = +12.7 K (J/hc = +8.82 cm(-1)) and a S = 3 ground state for 1 and J/k = +0.20 K (J/hc = +0.14 cm(-1)) and a S = 15 ground state for 2, when only J refers to the isotropic magnetic-exchange interactions for first-neighbor atoms of the approximately equilateral Cu6(12+) and Mn6(12+) hexagons. The single-crystal ESR spectroscopy of 1 under the orientation of the magnetic field along a Cu6 hexagon's nearly 6-fold axis equal to the c axis on the variation of temperature supports the S = 3 ground state and allows an estimate of the zero-field (fine-structure) energy separation between Sz = 0 and Sz = +/-1 of D = -0.182 K to be obtained.     

Rotationally correlated reactivity in the CH (v = 0, J, F(i)) + O2 → OH (A) + CO reaction

The rotational-state-selected CH (v = 0, J, F(i)) beam has been prepared by using an electric hexapole and applied to the crossed beam reaction of CH (v = 0, J, F(i)) + O(2) → OH (A) + CO at different O(2) beam conditions. The rotational state selected reactive cross sections of CH (RSSRCS-CH) turn out to depend remarkably on the rotational state distribution of O(2) molecules at a collision energy of ～?0.19 eV. The reactivity of CH molecules in the N = 1 rotational states (namely ∣J = 1∕2, F(2)> and ∣J = 3∕2, F(1)> states, N designates the angular momentum excluding spin) becomes strongly enhanced upon a lowering of the rotational temperature of the O(2) beam. The RSSRCS-CH in these two rotational states correlate linearly with the population of O(2) molecule in the specific K(O(2)) frame rotation number states: CH(|J = 1/2,F(2)>) with O(2)(|K(O(2)) = 1>);CH(|J = 3/2,F(1)>) with O(2)(|K(O(2)) = 3>). These linear correlations mean that the rotational-state-selected CH molecules are selectively reactive upon the incoming O(2) molecules in a specific rotational state; here, we use the term "rotationally correlated reactivity" to such specific reactivity depending on the combination of the rotational states between two molecular reactants. In addition, the steric asymmetry in the oriented CH (∣J = 1∕2,?F(2),?M = 1∕2>) + O(2) (|K(O(2)) = 1>) reaction turns out to be negligible (< ±1%). This observation supports the reaction mechanism as theoretically predicted by Huang et al. [J. Phys. Chem. A 106, 5490 (2002)] that the first step is an intermediate formation with no energy barrier in which C-atom of CH molecule attacks on one O-atom of O(2) molecule at a sideways configuration.