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Transition metal phosphides have been regarded as promising HER electrocatalysts for water splitting, the efficiency mass-transfer mechanism can be promoted through constructing microporous structure. In addition, introducing carbon materials as carriers to form interface interaction is beneficial for increasing electronic conductivity so as to promote the catalytic activity furtherly. In this work, a nitrogen-doped graphene (NGO) supported microporous nickel phosphide-nickel phosphite (Ni2P-Ni11(HPO3)8(OH)6@NGO, Ni2P-MPH@NGO), where Ni2P nanoparticles are uniformly filled in the microporous of Ni11(HPO3)8(OH)6 and then supported on the two-dimension NGO via a simple two-step method, has been studied as a novel efficient electrocatalyst for HER. Compared with carbon nanotube and graphene as carbon-based carriers, the optimized Ni2P-MPH@NGO catalyst shows excellent HER performance with a smaller overpotential, lower Tafel slope, as well as long-term catalytic durability under acid conditions. The results demonstrated that the NGO can enhance the catalytic activity of Ni2P-MPH@NGO efficiently. The results show that the synergistic effect of the microporous structure of MPH and NGO effectively improves the catalytic activity of the Ni2P-MPH@NGO composite catalyst, which provides a promising strategy for the design of a new low-cost and high-efficiency HER electrocatalyst.Objective Restoration of central vision loss in patients with age-related macular degeneration (AMD) by implanting a retinal prosthesis is associated with an intriguing situation wherein the central prosthetic vision co-exists with natural normal vision. Of major interest are the interactions between the prosthetic and natural vision. Here we studied the effect of the light-adaptive state of the normal retina on the electrical visual evoked potentials arising from the retinal prosthesis. Approach We recorded electrical visual evoked potential elicited by prosthetic retinal stimulation in wild-type rats implanted with a 1-mm photovoltaic subretinal array. Cortical responses were recorded following overnight dark adaption and compared to those recorded following bleaching of the retina by light (520nm) at various intensities and durations. Main Results Compared to dark-adapted responses, bleaching induced a 2-fold decrease in the prosthetic cortical response, which returned to the dark-adapted baseline within 30 min to several hours, depending on the degree of bleaching. This reduction was neither observed in Royal College of Surgeons (RCS) rats with a degenerated photoreceptor layer nor following intravitreal injection of a GABAa receptor blocker (bicuculine), suggesting the involvement of photoreceptors and a GABAa-mediated mechanism. Significance These findings show a robust effect of the retinal light-adaptive state on the obtained prosthetic responses. If a similar effect is found in humans, this will have immediate implications on the design of prosthetic devices, where both natural and prosthetic vision co-exist, such as in AMD patients receiving a photovoltaic retinal implant. Similarly, standardization of the retinal light-adaptive state in prosthetic clinical trials should be considered.A 3D printing system able to print circuits of conductive epoxy resin doped with carbon nanotubes (CNTs) is proposed. Different simple circuits, more specifically lines and strain gauge patterns, made of resins reinforced with 0.3, 0.5, 0.8 and 1 wt% of CNTs were printed on the surface of glass fiber laminates. It was observed that increasing the CNT content reduced the wettability of the printed circuits on the glass fiber substrate. In every case the contact angle was far below 90°. Furthermore, the strain sensing capabilities were analyzed under a flexural load. selleck The results showed that the sensitivity increased with CNT content (with gauge factor values from 1.5 to 2.5) as a result of the prevalent effect of well-dispersed areas due to a reduction in the tunneling distance. On the other hand, the strain gauges showed a lower sensitivity (around 20%-40% less, depending on the condition) compared with line circuits due to localized compressive effects. Furthermore, good repeatability of the strain sensors was proved during cycling tests, with similar baseline and peak values for the electrical resistance in each cycle. Therefore, the proposed materials have a high potential for applications in structural health monitoring.Objectives.Accurate seizure prediction is highly desirable for medical interventions such as responsive electrical stimulation. We aim to develop a classification model that can predict seizures by identifying preictal states, i.e. the precursor of a seizure, based on multi-channel intracranial electroencephalography (iEEG) signals.Approach.A two-level sparse multiscale classification model was developed to classify interictal and preictal states from iEEG data. In the first level, short time-scale linear dynamical features were extracted as autoregressive (AR) model coefficients; arbitrary (usually long) time-scale linear and nonlinear dynamical features were extracted as Laguerre-Volterra AR model coefficients; root-mean-square error of model prediction was used as a feature representing model unpredictability. In the second level, all features were fed into a sparse classifier to discriminate the iEEG data between interictal and preictal states.Main results. The two-level model can accurately classify seizure states using iEEG data recorded from ten canine and human subjects. Adding arbitrary (usually long) time-scale and nonlinear features significantly improves model performance compared with the conventional AR modeling approach. There is a high degree of variability in the types of features contributing to seizure prediction across different subjects.Significance. This study suggests that seizure generation may involve distinct linear/nonlinear dynamical processes caused by different underlying neurobiological mechanisms. It is necessary to build patient-specific classification models with a wide range of dynamical features.We report on the resistive memory effects of a Ag/CoFe2O4/Pt device and a deterministic conversion between volatile and nonvolatile resistive switching (RS) memory through the tuning of current compliance (I CC). For the smaller I CC (10-4 A) the device exhibits volatile RS behavior with an atomically sized conducting filament showing the quantum conductance. For an intermediate I CC (10-2 A) nonvolatile bipolar RS behavior is observed, which could originate from the formation and rupture of filament consisting of Ag ions. The high resistance state (HRS) of the device shows a semiconducting conduction mechanism, whereas the low resistance state (LRS) was found to be Ohmic in nature. The temperature dependent resistance studies and magnetization studies indicated that the electrochemical metallization plays a dominant role in the resistive switching process for volatile and nonvolatile modes through the formation of Ag conducting filaments. For higher I CC (10-1 A) the device permanently switches to LRS. The irreversible RS memory behaviors, observed for higher I CC, could be attributed to the formation of a thick and stable conducting channel formed of oxygen vacancies and Ag ions. The compliance current controlled resistive switching modes with a large memory window make the present device a potential candidate to pave the way for future resistive switching devices.We study excitations of atomic vibrations in the reciprocal space for amorphous solids. link2 There are two kinds of excitations we obtained, collective excitation and local excitation. The collective excitation is the collective vibration of atoms in the amorphous solids while the local excitation is stimulated locally by a single atom vibrating in the solids. We introduce a continuous wave vector for the study and transform the equations of atomic vibrations from the real space to the reciprocal space. We take the amorphous silicon as an example and calculate the structures of the excitations in the reciprocal space. Results show that an excitation is a wave packet composed of a collection of plane waves. We also find a periodical structure in the reciprocal space for the collective excitation with longitudinal vibrations, which is originated from the local order of the structure in the real space of the amorphous solid.For the local excitation, the wave vector is complex. The imaginary part of the wave vector is inversed to evaluate the decaying length of the local excitation. It is found that the decaying length is larger for the local excitation with a higher vibration frequency.Slide-ring elastomers have garnered a lot of interest for their potential use in dielectric elastomer actuators due to their intrinsically soft nature and high elasticity. However, the use of sliding cross-linkers has been constrained by their low miscibility with commonly used elastomer precursors and the specialized curing chemistries that are necessary for incorporating them into networks. Here, we have presented a method to produce vinyl functional polyrotaxane cross-linkers that are compatible with polysiloxanes and can be processed by industrially scalable methods. The sliding silicone films that were fabricated with these novel cross-linkers were highly extensible (>350%) and did not exhibit strain hardening even at high elongation. The composite films also retained the favorable dielectric properties of silicone elastomers such as the characteristic low dielectric loss. The modified polyrotaxanes present a robust platform for producing a new class of sliding silicone elastomers with well-defined networks structures.Human bone marrow mesenchymal stem cells (HBMSCs) are regarded as an important resource in the field of maxillofacial bone regeneration because of their favorable properties when compared with other stem cells. Hence, finding suitable materials that could extend the application of HBMSCs has become an emerging medical topic and socioeconomic problem. In this work, polydopamine (PDA)-Ag surface was fabricated by PDA assisted photoreduction method, and the obtained PDA-Ag composite surface significantly promoted HBMSCs adhesion and proliferation. This effect is highly related to the amount of Ag nanoparticles (Ag NPs) present on the PDA surface. The behavior of HBMSCs on PDA-Ag surface could be spatially manipulated by controlling the distribution of Ag NPs on PDA surface (by controlling UV light). link3 The general adhesion property allows the PDA-Ag surface to be fabricated on various substrates, making it a simple, general and controllable method for the fabrication of bioactive surface for HBMSCs.Being a carbon-based hybrid, graphene-semiconductor composites have attracted considerable attention in recent decades owing to their potential features such as high photosensitivity, extended light absorption, and effective separation of charge carriers, thus have been regarded as a promising platform for environmental and biomedical applications, respectively. In this mini-review, we first summarized the recent advancements in the development of graphene-based semiconductor nanocomposites via sol-gel, solution mixing, in situ growth, hydrothermal, and solvothermal approaches, and then comprehensively reviewed their potential light activated cancer phototherapeutic applications. Finally, we rationally analyze the current challenges and new perspectives for the future development of more effective phototherapeutic nanoagents. We hope to offer enriched information to harvest the utmost fascinating properties of graphene as a platform to construct efficient graphene/semiconductor hybrids for cancer phototherapy.
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