首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 15 毫秒
1.
Heretofore only observed in living systems, we report that weak-field ion cyclotron resonance (ICR) also occurs in inanimate matter. Weak magnetic field (50 nT) hydronium ICR at the field combination (7.84 Hz, 7.5 µT) markedly changes water structure, as evidenced by finding an altered index of refraction exactly at this combined field. This observation utilizes a novel technique which measures the scattering of a He–Ne laser beam as the sample is exposed to a ramped magnetic field frequency. In addition to the hydronium resonance, we find evidence of ICR coupling to a more massive structure, possibly a tetrahedral combination of three waters and a single hydronium ion. To check our observations, we extended this technique to D2O, successfully predicting the specific ICR charge-to-mass ratio for D3O+ that alters the index of refraction.  相似文献   

2.
A helitetrahedral model has been proposed to help explain reports of low-frequency oscillations in pure water following electromagnetic excitation at the hydronium ion cyclotron resonance frequency. The Lorentz force and the intrinsic structure constrain the motion of the H3O+ ion so that it enjoys a unique form of proton-hopping, one whose path is helical. This model may also explain the numerous previously observed cyclotron resonance (ICR) biological couplings for cations other than hydronium by merely substituting hydrogen-bonded versions of these for hydronium in the tetrahedral structure. Thus the effectiveness of resonance stimulation in biological systems is explained in terms of the enhanced conductivity and reduced scattering associated with proton-hopping. It is further shown that the addition of charge-balancing hydroxyl ions act to enable oscillatory electric dipole moments that propagate along the helical axis, giving rise to weak power (≈ femtoWatts) radiation patterns. It is conceivable that the radiation associated with this process may play a role in the interactions at the interface between water and living matter.  相似文献   

3.
One of the main problems of bioelectromagnetics - the unbelievable narrow resonance peaks at the cyclotron frequency of the alternating magnetic field - was considered. Modern electrodynamics of condensed matter clearly brings out that the reason of this phenomenon is extremely low viscosity within coherence domains of aqueous electrolytic solutions. The electrochemical model of action of combined static and alternating magnetic fields on aqueous solutions of amino acids is proposed. The possibility of arising a succession of changes in ionic forms in these processes was revealed. The dipole ions (zwitterions) together with water molecules electrostatically forming joint groups in the solution, create favorable conditions for arising mixed coherence domains there. Simultaneously with evolution of the coherent processes in these domains, the amino acid zwitterions are transforming into the usual ionic form, fit for cyclotron resonance. The development of cyclotron resonance under action of combined magnetic fields increases the ion kinetic energy, and the ions leave the domains for the incoherent component of the solution according to Del Giudice pattern (Comisso et al., 2006; Del Giudice et al., 2002), creating the peak current through the solution. Then the ions are transforming little by little into zwitterionic form again; after that, the solution becomes ready to react on exposure of magnetic fields again. The possibilities for formation of coherence domains composed of water molecules together with peptide molecules or protein ones are discussed.  相似文献   

4.

Background  

Weak magnetic and electromagnetic fields can influence physiological processes in animals, plants and microorganisms, but the underlying way of perception is poorly understood. The ion cyclotron resonance is one of the discussed mechanisms, predicting biological effects for definite frequencies and intensities of electromagnetic fields possibly by affecting the physiological availability of small ions. Above all an influence on Calcium, which is crucial for many life processes, is in the focus of interest. We show that in Arabidopsis thaliana, changes in Ca2+-concentrations can be induced by combinations of magnetic and electromagnetic fields that match Ca2+-ion cyclotron resonance conditions.  相似文献   

5.
The parameters of a calcium plasma source based on an electron cyclotron resonance (ECR) discharge were calculated. The analysis was performed as applied to an ion cyclotron resonance system designed for separation of calcium isotopes. The plasma electrons in the source were heated by gyrotron microwave radiation in the zone of the inhomogeneous magnetic field. It was assumed that, in such a combined trap, the energy of the extraordinary microwave propagating from the high-field side was initially transferred to a small group of resonance electrons. As a result, two electron components with different transverse temperatures—the hot resonance component and the cold nonresonance component—were created in the plasma. The longitudinal temperatures of both components were assumed to be equal. The entire discharge space was divided into a narrow ECR zone, where resonance electrons acquired transverse energy, and the region of the discharge itself, where the gas was ionized. The transverse energy of resonance electrons was calculated by solving the equations for electron motion in an inhomogeneous magnetic field. Using the law of energy conservation and the balance condition for the number of hot electrons entering the discharge zone and cooled due to ionization and elastic collisions, the density of hot electrons was estimated and the dependence of the longitudinal temperature T e of the main (cold) electron component on the energy fraction β lost for radiation was obtained.  相似文献   

6.
Weak magnetic and electromagnetic fields affect physiological processes in animals, plants, and microorganisms. Ion cyclotron resonance (ICR) is discussed as one of the sensitive mechanisms, which enable perception of the geomagnetic field and its orientation. Numerous biological effects are observed involving several small ions, showing windows of predicted frequencies and intensities. The pioneering work of Guiliano Preparata and Emilio Del Giudice using quantum electrodynamics showed that spontaneously originating coherent regions in water facilitate ICR effects at incoherent water phase boundaries. Here we examine the ICR response of the calcium ion (Ca2+), crucial for many life processes. We use an aqueous solution containing the biologically ubiquitous membrane lipid L-α-phosphatidylcholine that serves as a biomimetic proxy for dynamic light scattering (DLS) and nonlinear dielectric spectroscopy (NLDS) measurements. One notable result is that this system approaches a new equilibrium upon addition of calcium by means of the oscillatory Belousov–Zhabotinsky chemical reaction, oscillations are significantly reduced under Ca2+ ICR application. Secondly an “oscillator” of calcium ions appears to be able to itself couple coherently and predictably to large-scale coherent regions in water. This system appears able to regulate ion fluxes in response to very weak environmental electromagnetic fields.  相似文献   

7.
The purpose of this study was to determine the effect of extremely low frequency and weak magnetic fields (WMF) on cardiac myocyte Ca2+ transients, and to explore the involvement of potassium channels under the WMF effect. In addition, we aimed to find a physical explanation for the effect of WMF on cardiac myocyte Ca2+ transients. Indo‐1 loaded cells, which were exposed to a WMF at 16 Hz and 40 nT, demonstrated a 75 ± 4% reduction in cytosolic Ca2+ transients versus control. Treatment with the KATP channel blocker, glibenclamide, followed by WMF at 16 Hz exposure, blocked the reduction in cytosolic calcium transients while treatment with pinacidil, a KATP channel opener, or chromanol 293B, a selective potassium channel blocker of the delayed rectifier K+ channels, did not inhibit the effect. Based on these finding and the ion cyclotron resonance frequency theory, we further investigated the effect of WMF by changing the direct current (DC) magnetic field (B0). When operating different DC magnetic fields we showed that the WMF value changed correspondingly: for B0 = 44.5 µT, the effect was observed at 17.05 Hz; for B0 = 46.5 µT, the effect was observed at 18.15 Hz; and for B0 = 49 µT the effect was observed at 19.1 Hz. We can conclude that the effect of WMF on Ca2+ transients depends on the DC magnetic field level. Bioelectromagnetics 33:634–640, 2012. © 2012 Wiley Periodicals, Inc.  相似文献   

8.
Novikov  V. V.  Sheiman  I. M. 《Biophysics》2012,57(2):244-246
It is shown that treatment with combined constant (42 μT) and alternating magnetic field at 32 Hz (corresponding to the cyclotron frequency for Ca2+ ion) parallel thereto exerts influence on the intensity of planarian fission that depends on the amplitude of the alternating magnetic field. At the alternating component of 100 nT magnitude a stimulatory effect is noted, at 250 nT the number of planarians significantly decreases, while at 500 nT no magnetic field action is registered.  相似文献   

9.
We consider the possibility that DC magnetic fields can interact in a resonant manner with endogenous AC electric fields in biological systems. Intrinsic electric-field ion cyclotron resonance (ICR) interactions would be more physically credible than models based on external AC magnetic fields and might be expected as an evolutionary response to the long-term constancy of the geomagnetic field. Bioelectromagnetics 17:85–87, 1997. © 1997 Wiley-Liss, Inc.  相似文献   

10.
Although considerable experimental evidence now exists to indicate that low-frequency magnetic fileds influence living cells, the mode of coupling remains a mystery. We propose a radical new model for electromagnetic interactions with cells, one resulting from a cyclotron resonance mechanism attached to ions moving through transmembrane channels. It is shown that the cyclotron resonance condition on such ions readily leads to a predicted ELF-coupling at geomagnetic levels. This model quantitatively explains the results reported by Blackman et al. (1984), identifying the focus of magnetic interaction in these experiments as K+ charge carriers. The cyclotron resonance concept is consistent with recent indications showing that many membrane channels have helical configurations. This model is quite testable, can probably be applied to other circulating charge components within the cell and, most important, leads to the feasibility of direct resonant electromagnetic energy transfer to selected compartments of the cell.  相似文献   

11.
Physical processes determining the excitation of RF electromagnetic fields in a plasma column in a magnetic field are analyzed. The Alfvén resonance plays an important role at frequencies close to the ion cyclotron frequency. It leads to the enhancement of the RF electric field and transformation of Alfvén oscillations with a predominantly transverse polarization of the electric field into lower hybrid ones, which have a significant longitudinal component of the electric field. Lower hybrid oscillations efficiently interact with electrons causing their heating. Difficulties in the implementation of ion cyclotron resonance heating by the magnetic beach method are outlined. The processes considered in this work can be important for the VASIMR plasma engine.  相似文献   

12.
Photosystem II uses water as an enzymatic substrate. It has been hypothesized that this water is vectored to the active site for water oxidation via water channels that lead from the surface of the protein complex to the Mn4O5Ca metal cluster. The radiolysis of water by synchrotron radiation produces amino acid residue-modifying OH and is a powerful technique to identify regions of proteins that are in contact with water. In this study, we have used this technique to oxidatively modify buried amino acid residues in higher plant Photosystem II membranes. Fourier transform ion cyclotron resonance mass spectrometry was then used to identify these oxidized amino acid residues that were located in several core Photosystem II subunits (D1, D2, CP43, and CP47). While, as expected, the majority of the identified oxidized residues (≈75%) are located on the solvent-exposed surface of the complex, a number of buried residues on these proteins were also modified. These residues form groups which appear to lead from the surface of the complex to the Mn4O5Ca cluster. These residues may be in contact with putative water channels in the photosystem. These results are discussed within the context of a number of largely computational studies that have identified putative water channels in Photosystem II.  相似文献   

13.
15N-1H 1J couplings were measured at 500 MHz and 800 MHz for 15N enriched oxidized cytochrome b 562 from E. coli. The magnetic field dependence of 70 1J values, which could be measured without signal overlap, shows that there is a molecular magnetic anisotropy which provides partial molecular orientation in the magnetic field and, consequently, residual dipolar couplings (rdc). The rdc were used as further constraints to improve the existing structure [Arnesano et al. (1999) Biochemistry, 38, 8657–8670] with a protocol which uses the rhombic anisotropy [Banci et al. (1998) J. Am. Chem. Soc., 120, 12903–12909]. The overall large molecular magnetic anisotropy has been found to be determined by both the low spin iron (III) and the four helix bundle structure magnetic susceptibility anisotropy contributions.  相似文献   

14.
Abstract

Nanosecond scale molecular dynamics simulations have been performed on antiparallel Greek key type d(G7) quadruplex structures with different coordinated ions, namely Na+ and K+ ion, water and Na+ counter ions, using the AMBER force field and Particle Mesh Ewald technique for electrostatic interactions. Antiparallel structures are stable during the simulation, with root mean square deviation values of ~ 1.5 Å from the initial structures. Hydrogen bonding patterns within the G-tetrads depend on the nature of the coordinated ion, with the G-tetrad undergoing local structural variation to accommodate different cations. However, alternating syn-anti arrangement of bases along a chain as well as in a quartet is maintained through out the MD simulation. Coordinated Na+ ions, within the quadruplex cavity are quite mobile within the central channel and can even enter or exit from the quadruplex core, whereas coordinated K+ ions are quite immobile. MD studies at 400K indicate that K+ ion cannot come out from the quadruplex core without breaking the terminal G-tetrads. Smaller grooves in antiparallel structures are better binding sites for hydrated counter ions, while a string of hydrogen bonded water molecules are observed within both the small and large grooves. The hydration free energy for the K+ ion coordinated structure is more favourable than that for the Na+ ion coordinated antiparallel quadruplex structure.  相似文献   

15.
We recently developed a method for estimating protein dynamics in vivo with heavy water (2H2O) using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI–TOF MS) [16], and we confirmed that 2H labeling of many hepatic free amino acids rapidly equilibrated with body water. Although this is a reliable method, it required modest sample purification and necessitated the determination of tissue-specific amino acid labeling. Another approach for quantifying protein kinetics is to measure the 2H enrichments of body water (precursor) and protein-bound amino acid or proteolytic peptide (product) and to estimate how many copies of deuterium are incorporated into a product. In the current study, we used nanospray linear trap Fourier transform ion cyclotron resonance mass spectrometry (LTQ FT–ICR MS) to simultaneously measure the isotopic enrichment of peptides and protein-bound amino acids. A mathematical algorithm was developed to aid the data processing. The most notable improvement centers on the fact that the precursor/product labeling ratio can be obtained by measuring the labeling of water and a protein (or peptide) of interest, thereby minimizing the need to measure the amino acid labeling. As a proof of principle, we demonstrate that this approach can detect the effect of nutritional status on albumin synthesis in rats given 2H2O.  相似文献   

16.
Extremely-low-frequency (ELF), low-intensity magnetic fields have been shown to influence cell signaling processes in a variety of systems, both in vivo and in vitro. Similar effects have been demonstrated for nervous system development and neurite outgrowth. We report that regeneration in planaria, which incorporates many of these processes, is also affected by ELF magnetic fields. The rate of cephalic regeneration, reflected by the mean regeneration time (MRT), for planaria populations regenerating under continuous exposure to combined DC (78.4 μT) and AC (60.0 Hz at 10.0 μT peak) magnetic fields applied in parallel was found to be significantly delayed (P ? 0.001) by 48 ± 1 h relative to two different types of control populations (MRT ? 140 ± 12 h). One control population was exposed to only the AC component of this field combination, while the other experienced only the ambient geomagnetic field. All measurements were conducted in a low-gradient, low-noise magnetics laboratory under well-maintained temperature conditions. This delay in regeneration was shown to be dependent on the planaria having a fixed orientation with respect to the magnetic field vectors. Results also indicate that this orientation-dependent transduction process does not result from Faraday induction but is consistent with a Ca2+ cyclotron resonance mechanism. Data interpretation also permits the tentative conclusion that the effect results from an inhibition of events at an early stage in the regeneration process before the onset of proliferation and differentiation. © 1995 Wiley-Liss, Inc.  相似文献   

17.
The metric of prime interest in power line epidemiological studies has been AC magnetic intensity. To consider also possible geomagnetic involvement, the orientation of a long straight power line is examined relative to a uniform geomagnetic field (GMF) with dip angle α. An expression is derived for the component of the total GMF that is parallel, at an elevation β, to the circuital magnetic field that surrounds the line. This component is a function of the angles α and β, the total geomagnetic intensity BT, and the angle θ between the axis of the power line and magnetic north. Plotting these geomagnetic parameters for known leukemia residences allows one to test for possible ion cyclotron resonance or other GMF interactions. This approach, in principle, is an easy addition to existing or planned studies, because residential access is not required to obtain local values for α, β, θ, and BT. We recommend including these parameters in the design of epidemiological studies examining power line fields and childhood leukemia. © 1995 Wiley-Liss, Inc.  相似文献   

18.
摘要 目的:以超小超顺磁性氧化铁颗粒为载体通过聚乙二醇连接荧光Cy5.5构建核磁/荧光分子探针并表征。方法:取Cy5.5-NHS荧光粉末溶于二甲基甲砜(Dimethyl sulfoxide,DMSO)溶液,将PEG四氧化三铁颗粒离心超滤之后用磷酸盐缓冲液(Phosphate Buffered Saline,PBS)重悬纳米颗粒改变PEG化四氧化三铁纳米颗粒溶液pH。将配置好的Cy5.5荧光加入到四氧化三铁颗粒中,恒温摇床孵育,通过离心过滤器去除较大铁离子与未结合的荧光,静置后检测水合粒径及Zeta电位,纽麦小核磁检测其驰豫率,CCK-8实验检测其细胞毒性,激光共聚焦显微镜观察探针被细胞摄取情况。结果:合成Cy5.5-PEG-FeO4探针,透射电镜(Transmission electron microscope,TEM)显示探针粒径为16.8±2.4nm,纳米颗粒的水合径为43.4±17.6 nm,Zeta电位为-18.0 mV。驰豫率为39.5 mM-1?s-1,R2为0.98。细胞毒性实验结果显示对细胞有轻微毒性,且毒性与浓度呈依赖性。激光共聚焦结果显示此款探针可顺利被细胞摄取。结论:成功合成Cy5.5-PEG-FeO4探针。  相似文献   

19.
Measuring metabolism''s time- and space-dependent responses upon stimulation lies at the core of functional magnetic resonance imaging. While focusing on water''s sole resonance, further insight could arise from monitoring the temporal responses arising from the metabolites themselves, in what is known as functional magnetic resonance spectroscopy. Performing these measurements in real time, however, is severely challenged by the short functional timescales and low concentrations of natural metabolites. Dissolution dynamic nuclear polarization is an emerging technique that can potentially alleviate this, as it provides a massive sensitivity enhancement allowing one to probe low-concentration tracers and products in a single-scan. Still, conventional implementations of this hyperpolarization approach are not immediately amenable to the repeated acquisitions needed in real-time functional settings. This work proposes a strategy for functional magnetic resonance of hyperpolarized metabolites that bypasses this limitation, and enables the observation of real-time metabolic changes through the synchronization of stimuli-triggered, multiple-bolus injections of the metabolic tracer 13C1-pyruvate. This new approach is demonstrated with paradigms tailored to reveal in vivo thresholds of murine hind-limb skeletal muscle activation, involving the conversion of 13C1-pyruvate to 13C1-lactate and 13C1-alanine. These functional hind-limb studies revealed that graded skeletal muscle stimulation causes commensurate increases in glycolytic metabolism in a frequency- and amplitude-dependent fashion, that can be monitored on the seconds/minutes timescale using dissolution dynamic nuclear polarization. Spectroscopic imaging further allowed the in vivo visualization of uptake, transformation and distribution of the tracer and products, in fast-twitch glycolytic and in slow-twitch oxidative muscle fiber groups. While these studies open vistas in time and sensitivity for metabolic functional magnetic resonance studies in muscle, the simplicity of our approach makes this technique amenable to a wide range of functional metabolic tracer studies.  相似文献   

20.
Proton magnetic resonance spectroscopy has been used to study the nature of water in human stratum corneum. For a single planar sheet of stratum corneum mounted at a specific orientation to the applied magnetic field, three distinct absorptions may be seen having different chemical shifts and spin-lattice relaxation times (T1). All T1 values for these resonances are smaller than that for normal liquid water. One absorption is unusual in that the resonance position is dependent upon the orientation of the sample within the field.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号