Acupuncture has been accepted to effectively treat chronic pain by inserting needles into the specific "acupuncture points" (acupoints) on the patient's body. During the last decades, our ...understanding of how the brain processes acupuncture analgesia has undergone considerable development. Acupuncture analgesia is manifested only when the intricate feeling (soreness, numbness, heaviness and distension) of acupuncture in patients occurs following acupuncture manipulation. Manual acupuncture (MA) is the insertion of an acupuncture needle into acupoint followed by the twisting of the needle up and down by hand. In MA, all types of afferent fibers (Abeta, Adelta and C) are activated. In electrical acupuncture (EA), a stimulating current via the inserted needle is delivered to acupoints. Electrical current intense enough to excite Abeta- and part of Adelta-fibers can induce an analgesic effect. Acupuncture signals ascend mainly through the spinal ventrolateral funiculus to the brain. Many brain nuclei composing a complicated network are involved in processing acupuncture analgesia, including the nucleus raphe magnus (NRM), periaqueductal grey (PAG), locus coeruleus, arcuate nucleus (Arc), preoptic area, nucleus submedius, habenular nucleus, accumbens nucleus, caudate nucleus, septal area, amygdale, etc. Acupuncture analgesia is essentially a manifestation of integrative processes at different levels in the CNS between afferent impulses from pain regions and impulses from acupoints. In the last decade, profound studies on neural mechanisms underlying acupuncture analgesia predominately focus on cellular and molecular substrate and functional brain imaging and have developed rapidly. Diverse signal molecules contribute to mediating acupuncture analgesia, such as opioid peptides (mu-, delta- and kappa-receptors), glutamate (NMDA and AMPA/KA receptors), 5-hydroxytryptamine, and cholecystokinin octapeptide. Among these, the opioid peptides and their receptors in Arc-PAG-NRM-spinal dorsal horn pathway play a pivotal role in mediating acupuncture analgesia. The release of opioid peptides evoked by electroacupuncture is frequency-dependent. EA at 2 and 100Hz produces release of enkephalin and dynorphin in the spinal cord, respectively. CCK-8 antagonizes acupuncture analgesia. The individual differences of acupuncture analgesia are associated with inherited genetic factors and the density of CCK receptors. The brain regions associated with acupuncture analgesia identified in animal experiments were confirmed and further explored in the human brain by means of functional imaging. EA analgesia is likely associated with its counter-regulation to spinal glial activation. PTX-sesntive Gi/o protein- and MAP kinase-mediated signal pathways as well as the downstream events NF-kappaB, c-fos and c-jun play important roles in EA analgesia.
Janus membranes (JMs) with opposite wettability have brought about new opportunities to tackle the challenging issues encountered in oil/water separation. However, these achievements suffer from ...empirical availability for the separation of oil-in-water emulsions, lacking a controllable way to tune the synergistic effect of asymmetric configurations, which is the “inner” driving force for practical performance. Herein, the role of the asymmetric configuration is theoretically and experimentally demonstrated in the Janus structural design, membrane fabrication, and separation performance for oil-in-water emulsions. These significant insights are particularly gained by analyzing Young–Laplace capillary pressures, measuring the adhesive forces between the oil and membrane surface, and monitoring the demulsification and oil transportation processes. Fluorescence imaging has been used to in situ visualize the separation process and then a mechanism is firstly proposed as demulsification followed by rapid unidirectional oil transportation for surfactant-stabilized oil-in-water emulsions. The two successive processes are strongly governed by the controllable asymmetric configuration of the JMs. An efficient oil separation can, therefore, be achieved from surfactant-stabilized oil-in-water emulsions with a wide size distribution (from nanometers to microns) by optimizing these two stages via tuning the hydrophilic/hydrophobic configuration and surface charge property of the JMs. Therefore, this work is expected to yield a design principle and guideline for developing JMs with applicability in the practical separation of oil-in-water emulsions.
In this paper, we prove an exponential integral formula for the Fourier transform of Bessel functions over complex numbers, along with a radial exponential integral formula. The former will enable us ...to develop the complex spectral theory of the relative trace formula for the Shimura-Waldspurger correspondence and extend the Waldspurger formula from totally real fields to arbitrary number fields.
The tunable growth of metal–organic materials has implications for engineering particles and surfaces for diverse applications. Specifically, controlling the self‐assembly of metal–phenolic networks ...(MPNs), an emerging class of metal–organic materials, is challenging, as previous studies suggest that growth often terminates through kinetic trapping. Herein, kinetic strategies were used to temporally and spatially control MPN growth by promoting self‐correction of the coordinating building blocks through oxidation‐mediated MPN assembly. The formation and growth mechanisms were investigated and used to engineer films with microporous structures and continuous gradients. Moreover, reactive oxygen species generated by ultrasonication expedite oxidation and result in faster (ca. 30 times) film growth than that achieved by other MPN assembly methods. This study expands our understanding of metal–phenolic chemistry towards engineering metal–phenolic materials for various applications.
Kinetic assembly is an efficient strategy for rapidly and continuously growing metal–phenolic network materials. Using reactive oxygen species, films were grown about 30 times faster than with existing technologies. Furthermore, the films display unique microstructures and continuous film gradients, which are desirable properties for applications in drug delivery and separations.
Limited by its fixed effective Poisson’s ratio, the bond-based central force peridynamic theory fails to properly describe shear deformation of solids. In this paper, the classical peridynamic theory ...is enriched with bond rotation effect and reformulated in the thermodynamic framework with emphasis on mathematical derivation of the micro elastic moduli. The macroscopic strain energy of the peridynamic system is completed by involving the local shear stain for both 3D and 2D problems. In each case, the effective elasticity tensor is derived rationally and compared to the results of continuum solid mechanics, which allows relating the micro stiffness parameters to the common macro elastic constants. For validation, numerical tests are performed to assess the prediction of Poisson’s ratio. It is shown that the enriched peridynamic model is capable of removing to a large extent the limitation of Poisson’s ratio and consistent from the viewpoint of strain homogenization.
The X‐linked gene cyclin‐dependent kinase‐like 5 (CDKL5) encodes a serine/threonine kinase abundantly expressed in the brain. Mutations in CDKL5 have been associated with neurodevelopmental disorders ...characterized by early‐onset epileptic encephalopathy and severe intellectual disability, suggesting that CDKL5 plays important roles in brain development and function. Recent studies using cultured neurons, knockout mice, and human iPSC‐derived neurons have demonstrated that CDKL5 regulates axon outgrowth, dendritic morphogenesis, and synapse formation. The role of CDKL5 in maintaining synaptic function in the mature brain has also begun to emerge. Moreover, mouse models that are deficient for CDKL5 recapitulate some of the key clinical phenotypes in human patients. Here we review these findings related to the function of CDKL5 in the brain and discuss the underlying molecular and cellular mechanisms.
Supramolecular complexation is a powerful strategy for engineering materials in bulk and at interfaces. Metal–phenolic networks (MPNs), which are assembled through supramolecular complexes, have ...emerged as suitable candidates for surface and particle engineering owing to their diverse properties. Herein, we examine the supramolecular dynamics of MPNs during thermal transformation processes. Changes in the local supramolecular network including enlarged pores, ordered aromatic packing, and metal relocation arise from thermal treatment in air or an inert atmosphere, enabling the engineering of metal–oxide networks (MONs) and metal–carbon networks, respectively. Furthermore, by integrating photo‐responsive motifs (i.e., TiO2) and silanization, the MONs are endowed with reversible superhydrophobic (>150°) and superhydrophilic (≈0°) properties. By highlighting the thermodynamics of MPNs and their transformation into diverse materials, this work offers a versatile pathway for advanced materials engineering.
Supramolecular metal–phenolic networks, consisting of metal ions coordinated with phenolic motifs, can undergo selective thermodynamic transformations into nanoporous structures, including metal–carbon networks and metal–oxide networks, with tunable network organization and surface wettability.
The static solution of crack propagation problems can be an efficient way to find both the failure load of a structure and the shape of the crack pattern. The paper introduces two new implicit static ...solution procedures to study crack propagation problems by adopting a Peridynamic-based numerical tool, and compares them with the Sequentially Linear Analysis. We discretize the structures in space by adopting a coupled FEM–PD approach, which exploits the flexibility of FEM to reduce the overall computational cost of the simulation. The results of several numerical examples indicate the main novel conclusions of the paper: when using a PD-based software, controlling the maximum number of bonds broken in each iteration may increase significantly the accuracy of the solution and keep the computational cost to an acceptable level.
With elevated confining pressure and low temperatures, geomaterials may exhibit brittle-to-ductile failure transition due to increased cataclastic flow. In this work, we propose a modified ...phase-field damage model to capture this transition, wherein a portion χf of the plastic work that contributes to the fracture driving force, is assumed. In particular, we propose to compute χf based on a specific normalized stress parameter based on Byerlee's rule, which ranges from brittle tension fracture to cataclastic flow. In the former case, all the stored plastic free energy is assumed to contribute to fracture. However, in all other cases, the brittle fracture process at the macroscale is gradually suppressed with the increase of pressure, rendering a smaller value of χf. The proposed model includes eight material parameters, all of which can be calibrated from standard laboratory tests, i.e., conventional triaxial compressive experiments. To validate the performance of the proposed model, three pre-cracked specimens are constructed under plane strain conditions. Numerical simulations show that the predicted failure patterns agree with the experimental testing, which highlights the predictive capability of the model to capture brittle and ductile failure mechanisms. In addition, the proposed model can describe the brittle-ductile failure transition behavior in the homogeneous case and can predict the realistic failure process at the structural level.
•A modified phase-field method for geomaterials, which accounts for brittle-ductile failure transition, is presented.•The portion of the plastic work contributing to the damage driving force is varied with the stress state.•A specific distance measure to Byerlee's rule, which ranges from brittle tension fracture to cataclastic flow, is proposed.•The model is capable of distinguishing the fractures in tensile and compressive-shear modes.•A detailed calibration process of model parameters with validation on a few difficult benchmark problems are presented.
This paper presents a method to couple FEM meshes with ordinary state-based peridynamic grids. It generates a computational tool that is as efficient as computer methods based on classical continuum ...mechanics and as flexible as peridynamics in dealing with crack propagation. Moreover, it removes most of the problems due to the surface effects typical of nonlocal methods such as OSB-PD. The adaptive dynamic relaxation approach is used to solve linear elastic and crack propagation problems. The method is successfully applied to a complex crack propagation case in 3 D and is able to accurately reproduce the shape of the experimentally observed crack.
Celotno besedilo
Dostopno za:
BFBNIB, DOBA, GIS, IJS, IZUM, KILJ, KISLJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
PDF
