The electronic interaction between two terminal ferrocenyl units connected by the cobalt bis(dicarbollide) anion linker was investigated. The bis(ferrocenylethynyl)cobalt bis(dicarbollide) anion (3) ...linking the two ferrocenyl units with the cobalt bis(dicarbollide) anion was synthesized by the reaction of a zinc derivative of ethynylferrocene with the diiodocobalt bis(dicarbollide) anion using Pd0 catalyst in 75 % yield. Complex 3 was unambiguously characterized by NMR and IR spectroscopy, mass spectrometry, and single‐crystal X‐ray crystallography. The X‐ray structure of 3 reveals that the two ferrocenyl units are perpendicular to each other with a total distance of 1.86 nm between the two Fe metal centers. The cyclic voltammogram of 3 shows a single oxidation potential corresponding to the two ferrocenyl units. Time‐dependent density functional theory (TD‐DFT) studies on complex 3 in tandem with UV/Vis spectroscopic analysis indicate the dominance of the dicarbollide moiety in the LUMOs, and HOMO→LUMO transitions at 435 nm illustrate the charge transfer from the two ferrocenyl units to the cobalt bis(dicarbollide) linker.
The electronic interaction between two terminal ferrocenyl units connected by the cobalt bis(dicarbollide) anion was investigated by cyclic voltammetry, UV/Vis spectroscopy, and TD‐DFT calculations.
Cervical and trigeminal afferents innervate neighboring cranial territories, and their convergence on upper cervical dorsal horn neurons provides a potential substrate for pain referral in primary ...headache syndromes. Lamina I neurons are central to this mechanism, as they relay convergent nociceptive input to supraspinal pain centers. Unfortunately, little is known about the interactions between trigeminal and cervical afferents supplying Lamina I neurons. Here, we used rats of both sexes to show that cervical and trigeminal afferents interact via presynaptic inhibition, where monosynaptic inputs to Lamina I neurons undergo unidirectional as well as reciprocal presynaptic control. This means that afferent-driven presynaptic inhibition shapes the way trigeminal and cervical Aδ-fiber and C-fiber input reaches Lamina I projection neurons (PNs) and local-circuit neurons (LCNs). We propose that this inhibition provides a feedforward control of excitatory drive to Lamina I neurons that regulates their convergent and cervical-specific or trigeminal-specific processing modes. As a consequence, disruption of the trigeminal and cervical afferent-driven presynaptic inhibition may contribute to development of primary headache syndromes.
Cervical and trigeminal afferents innervate neighboring cranial territories, and their convergence on upper cervical dorsal horn neurons provides a potential substrate for pain referral in primary headache syndromes. Lamina I neurons are central to this mechanism as they relay convergent nociceptive input to supraspinal pain centers. Here, we show that cervical and trigeminal afferents interact via presynaptic inhibition, where inputs to Lamina I neurons undergo unidirectional as well as reciprocal control. The afferent-driven presynaptic inhibition shapes the trigeminocervical Aδ-fiber and C-fiber input to Lamina I neurons. This inhibition provides control of excitatory drive to Lamina I neurons that regulates their convergent and cervical-specific or trigeminal-specific processing modes. Disruption of this control may contribute to development of primary headache syndromes.
Deep-Water Neutrino Telescope in Lake Baikal Allakhverdyan, V. A.; Avrorin, A. D.; Avrorin, A. V. ...
Physics of atomic nuclei,
12/2021, Letnik:
84, Številka:
9
Journal Article
Recenzirano
The Baikal-GVD deep-water neutrino telescope of the cubic kilometer scale, focused on research in the field of astrophysics and particle physics, is being built in Lake Baikal. As of 2021, the ...effective volume of the detector reaches 0.4 km
3
for cascades generated by high-energy astrophysical neutrinos. The paper describes the design and basic characteristics of the telescope data acquisition system, discusses some aspects of deep-water engineering related to the deployment of the detector, and presents selected results obtained with the partially complete detector.
Serotonergic mechanisms play a central role in migraine pathology. However, the region-specific effects of serotonin (5-HT) mediated via multiple types of receptors in the nociceptive system are ...poorly understood. Using extracellular and patch-clamp recordings, we studied the action of 5-HT on the excitability of peripheral and central terminals of trigeminal afferents. 5-HT evoked long-lasting TTX-sensitive firing in the peripheral terminals of meningeal afferents, the origin site of migraine pain. Cluster analysis revealed that in majority of nociceptive fibers 5-HT induced either transient or persistent spiking activity with prevailing delta and theta rhythms. The 5-HT3-receptor antagonist MDL-72222 or 5-HT1B/D-receptor antagonist GR127935 largely reduced, but their combination completely prevented the excitatory pro-nociceptive action of 5-HT. The 5-HT3 agonist mCPBG activated spikes in MDL-72222-dependent manner but the 5HT-1 receptor agonist sumatriptan did not affect the nociceptive firing. 5-HT also triggered peripheral CGRP release in meninges, which was blocked by MDL-72222.5-HT evoked fast membrane currents and Ca2+ transients in a fraction of trigeminal neurons. Immunohistochemistry showed expression of 5-HT3A receptors in fibers innervating meninges. Endogenous release of 5-HT from degranulated mast cells increased nociceptive firing. Low pH but not histamine strongly activated firing. 5-HT reduced monosynaptic inputs from trigeminal Aδ- and C-afferents to the upper cervical lamina I neurons and this effect was blocked by MDL-72222. Consistent with central inhibitory effect, 5-HT reduced CGRP release in the brainstem slices. In conclusion, 5-HT evokes powerful pro-nociceptive peripheral and anti-nociceptive central effects in trigeminal system transmitting migraine pain.
•5-HT induced a robust nociceptive activity in peripheral nerve terminals in meninges.•5-HT3 receptors contributed to pro-nociceptive action 5-HT and CGRP release.•Cluster analysis revealed fibers with remarkably long-lasting firing activity.•In contrast to periphery, 5-HT inhibited central nerve terminals of nociceptors.
Nociceptive trigeminal afferents innervating craniofacial area, eg, facial skin and cranial meninges, project to a broad region in the medullary and upper cervical dorsal horn designated as the ...trigeminocervical complex. Lamina I neurons in the trigeminocervical complex integrate and relay peripheral inputs, thus playing a key role in both cranial nociception and primary headache syndromes. Because of the technically challenging nature of recording, the long-range trigeminal afferent inputs to the medullary and cervical lamina I neurons were not intensively studied so far. Therefore, we have developed an ex vivo brainstem-cervical cord preparation with attached trigeminal nerve for the visually guided whole-cell recordings from the medullary and cervical lamina I neurons. Two-thirds of recorded neurons generated intrinsic rhythmic discharges. The stimulation of the trigeminal nerve produced a complex effect; it interrupted the rhythmic discharge for hundreds of milliseconds but, if the neuron was silenced by a hyperpolarizing current injection, could elicit a discharge. The monosynaptic inputs from the trigeminal Aδ, high-threshold Aδ, low-threshold C, and C afferents were recorded in the medullary neurons, as well as in the cervical neurons located in the segments C1 to C2 and, to a lesser degree, in C3 to C4. This pattern of supply was consistent with our labelling experiments showing extensive cervical projections of trigeminal afferents. Excitatory inputs were mediated, although not exclusively, through AMPA/kainate and NMDA receptors, whereas inhibitory inputs through both GABA and glycine receptors. In conclusion, the trigeminocervical lamina I neurons receive a complex pattern of long-range monosynaptic and polysynaptic inputs from a variety of the trigeminal nociceptive afferents.
Magnetic biosensors are an important part of biomedical applications of magnetic materials. As the living tissue is basically a "soft matter." this study addresses the development of ferrogels (FG) ...with micron sized magnetic particles of magnetite and strontium hexaferrite mimicking the living tissue. The basic composition of the FG comprised the polymeric network of polyacrylamide, synthesized by free radical polymerization of monomeric acrylamide (AAm) in water solution at three levels of concentration (1.1 M, 0.85 M and 0.58 M) to provide the FG with varying elasticity. To improve FG biocompatibility and to prevent the precipitation of the particles, polysaccharide thickeners-guar gum or xanthan gum were used. The content of magnetic particles in FG varied up to 5.2 wt % depending on the FG composition. The mechanical properties of FG and their deformation in a uniform magnetic field were comparatively analyzed. FG filled with strontium hexaferrite particles have larger Young's modulus value than FG filled with magnetite particles, most likely due to the specific features of the adhesion of the network's polymeric subchains on the surface of the particles. FG networks with xanthan are stronger and have higher modulus than the FG with guar. FG based on magnetite, contract in a magnetic field 0.42 T, whereas some FG based on strontium hexaferrite swell. Weak FG with the lowest concentration of AAm shows a much stronger response to a field, as the concentration of AAm governs the Young's modulus of ferrogel. A small magnetic field magnetoimpedance sensor prototype with Co
Fe
Mo
Si
B
rapidly quenched amorphous ribbon based element was designed aiming to develop a sensor working with a disposable stripe sensitive element. The proposed protocol allowed measurements of the concentration dependence of magnetic particles in gels using magnetoimpedance responses in the presence of magnetite and strontium hexaferrite ferrogels with xanthan. We have discussed the importance of magnetic history for the detection process and demonstrated the importance of remnant magnetization in the case of the gels with large magnetic particles.
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Deployment of the deep-sea neutrino telescope Baikal-GVD continues in Lake Baikal. By April 2022, ten telescope clusters, which include 2880 optical modules, were put into operation. One of the ...urgent tasks of the Baikal project is to study the possibility of increasing the detection efficiency of the detector based on the experience of its operation and the results obtained with other neutrino telescopes in recent years. In this paper, the authors consider a variant of optimizing the telescope configuration by installing an additional string of optical modules between the detector clusters (external string). An experimental version of the external garland was installed in Lake Baikal in April 2022. The paper presents the results from calculations of the efficiency of registration of neutrino events for a new setup configuration, the technical implementation of the system for recording and collecting data from the external garland, and the first results of its full-scale tests in Lake Baikal.
Magnetic nanoparticles of iron oxide (MNPs) were prepared by the laser target evaporation technique (LTE). The main focus was on the fabrication of de-aggregated spherical maghemite MNPs with a ...narrow size distribution and enhanced effective magnetization. X-ray diffraction, transmission electron microscopy, magnetization and microwave absorption measurements were comparatively analyzed. The shape of the MNPs (mean diameter of 9 nm) was very close to being spherical. The lattice constant of the crystalline phase was substantially smaller than that of stoichiometric magnetite but larger than the lattice constant of maghemite. High value of M
s
up to 300 K was established. The 300 K ferromagnetic resonance signal is a single line located at a field expected from spherical magnetic particles with negligible magnetic anisotropy. The maximum obtained concentration of water based ferrofluid was as high as 10g/l of magnetic material. In order to understand the temperature and field dependence of MNPs magnetization, we invoke the core-shell model. The nanoparticles is said to have a ferrimagnetic core (roughly 70 percent of the caliper size) while the shell consists of surface layers in which the spins are frozen having no long range magnetic order. The core-shell interactions were estimated in frame of random anisotropy model. The obtained assembly of de-aggregated nanoparticles is an example of magnetic nanofluid stable under ambient conditions even without an electrostatic stabilizer.
Biomedical engineering is the most promising field for the application of ferrogels as scaffolds for cell culturing in regenerative medicine, targeted drug delivery, and biosensorics. This study is ...focused on the contribution of ferric-oxide magnetic nanoparticles (MNPs) to the biocompatibility of ferrogels with human dermal fibroblasts. The results of experiments with polyacrylamide gels filled with MNPs are presented. These experiments demonstrate that, regardless of the mechanical and electrical characteristics of ferrogels, MNPs have a significant effect on the biological activity of cells.
The possibilities of producing large batches of magnetic nanoparticles (MNPs) using electrical explocion of the wire (EEW), laser target evaporation, and spark discharge are considered. MNP ...bioapplications require production of magnetic materials in the form of as stabilized aqueous suspensions or hydrogels with magnetic fillers; therefore, some details of synthesis of these materials and their certification are discussed. The problems of the interaction of MNPs with biological systems, biocompatibility, the applicability of ferrogel substrata to cellular technology and regenerative medicine, and as biomimetics in the development of magnetic biosensors are considered. The results of analysis of some biological experiments with various suspensions prepared based on the same MNP batch are presented. An analysis of the examples of magnetic biodetection and existing theoretical approaches will allow estimation of prospects of this scientific direction to develop highly sensitive film sensors based on the giant magnetic impedance effect for biomedical applications.
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