Demand for pragmatic alternatives to carbon‐intensive fossil fuels is growing more strident. Hydrogen represents an ideal zero‐carbon clean energy carrier with high energy density. For hydrogen fuel ...to compete with alternatives, safe and high capacity storage materials that are readily cycled are imperative. Here, development of such a material, comprised of nickel‐doped Mg nanocrystals encapsulated by molecular‐sieving reduced graphene oxide (rGO) layers, is reported. While most work on advanced hydrogen storage composites to date endeavor to explore either nanosizing or addition of carbon materials as secondary additives individually, methods to enable both are pioneered: “dual‐channel” doping combines the benefits of two different modalities of enhancement. Specifically, both external (rGO strain) and internal (Ni doping) mechanisms are used to efficiently promote both hydriding and dehydriding processes of Mg nanocrystals, simultaneously achieving high hydrogen storage capacity (6.5 wt% in the total composite) and excellent kinetics while maintaining robustness. Furthermore, hydrogen uptake is remarkably accomplished at room temperature and also under 1 bar—as observed during in situ measurements—which is a substantial advance for a reversible metal hydride material. The realization of three complementary functional components in one material breaks new ground in metal hydrides and makes solid‐state materials viable candidates for hydrogen‐fueled applications.
A new and innovative dual‐doping strategy is employed to magnesium nanocrystal system that demonstrates a reversible hydrogen storage at moderate temperature range with an unprecedented storage performance. This result makes a remarkable advance towards safe and efficient solid‐state hydrogen storage, and it can be adapted to both mobile and stationary fuel cell system to power a wide range of applications.
Controlling ferroic orders (ferroelectricity, ferromagnetism and ferroelasticity) by optical methods is a significant challenge due to the large mismatch in energy scales between the order parameter ...coupling strengths and the incident photons. Here, we demonstrate an approach to manipulate multiple ferroic orders in an epitaxial mixed-phase BiFeO3 thin film at ambient temperature via laser illumination. Phase-field simulations indicate that a light-driven flexoelectric effect allows the targeted formation of ordered domains. We also achieved precise sequential laser writing and erasure of different domain patterns, which demonstrates a deterministic optical control of multiferroicity at room temperature. As ferroic orders directly influence susceptibility and conductivity in complex materials, our results not only shed light on the optical control of multiple functionalities, but also suggest possible developments for optoelectronics and related applications.The remote, non-volatile and reversible optical control of ferroic orders is challenging. Here, using laser illumination, multiple orders in epitaxial mixed-phase BiFeO3 are manipulated deterministically using a thermally driven flexoelectric effect.
•The addition of barium ion obviously improved the flame retardancy of alginate.•The addition of barium ion changed the thermal degradation behaviors of alginate.•Pyrolysis process of barium alginate ...produced much less gaseous compounds.•Possible thermal degradation mechanism of barium alginate was proposed according to the results of TG-FTIR and Py-GC–MS.
A bio-based barium alginate film was prepared via a facile ionic exchange and casting approach. Its flammability, thermal degradation and pyrolysis behaviors, thermal degradation mechanism were studied systemically by limiting oxygen index (LOI), vertical burning (UL-94), microscale combustion calorimetry (MCC), thermogravimetric analysis (TGA) coupled with Fourier transform infrared analysis (FTIR) and pyrolysis-gas chromatography–mass spectrometry (Py-GC–MS). It showed that barium alginate film had much higher LOI value (52.0%) than that of sodium alginate film (24.5%). Moreover, barium alginate film passed the UL-94 V-0 rating, while the sodium alginate film showed no classification. Importantly, peak of heat release rate (PHRR) of barium alginate film in MCC test was much lower than that of sodium alginate film, suggested that introduction of barium ion into alginate film significantly decreased release of combustible gases. TG-FTIR and Py-GC–MS results indicated that barium alginate produced much less flammable products than that of sodium alginate in whole thermal degradation procedure. Finally, a possible degradation mechanism of barium alginate had been proposed.
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•Ionic liquid functionalized BNNS (BNNS@IL) was performed by one-step ball milling.•High-orientation layered EP/BNNS@IL film was fabricated via CLbL blade-casting.•Well-dispersed ...BNNS@IL is highly stacked in EP matrix along the in-plane direction.•The film showed excellent anisotropic thermal conductivity and flame retardancy.
Increasing power density and excess heat production in integrated electronic devices create the strong demand for polymeric thermal management materials with excellent thermal stability, flame retardancy and thermal conductivity. To this end, high-performance ionic liquid-wrapped boron nitride nanosheets (BNNS@IL) were firstly simultaneously exfoliated and flame-retardant functionalized via one-step ball milling process based on the strong mechanochemical action. Epoxy (EP)-based layered films with highly in-plane oriented BNNS@IL were then fabricated by a novel, effective and solvent-free cyclic layer-by-layer (CLbL) blade-casting method. Arising from the highly flat oriented structure and rich flame-retardant functional groups of BNNS@IL, as well as the high compatibility between filler and matrix, the as-fabricated EP/BNNS@IL films exhibited high anisotropic thermal conductivity (K∥ of 8.3 and K⊥ of 0.8 W m−1 K−1), outstanding thermal stability and flame retardancy with a dramatic decrease in PHRR (104.2 W/g) and THR (8.1 kJ/g) corresponding to reductions of 72.9% and 75.7% compared with neat EP, respectively. Additionally, the flat oriented structure and strong interfacial interaction also endow EP/BNNS@IL films with high flexibility and excellent mechanical properties. Therefore, the high-effective CLbL casting method and the obtained high-performance EP-based film exhibit a significant potential application in high power flexible electrical devices and thermal management products.
Culture-led regeneration has been widely accepted by European cities as an important component of urban renewal and sustainable development. However, the instrumental role of culture in urban ...regeneration has revealed several controversies. The study aims at contributing to the debate on urban cultural policy and management by answering two research questions: What are the key success factors for sustainable culture-led regeneration? How can cities strike a balance between the dilemmas of culture-led regeneration? Based on a case study of Liverpool as the 2008 European Capital of Culture, this research draws on long-term and multi-faceted data. The study period is from 2007 to 2018, with a view to tracking the long-term impact of event. Liverpool’s strategies for sustainable culture-led regeneration are investigated from three aspects: cultural funding dilemma, economic dilemma and spatial dilemma. The findings reveal that incorporating events in a city’s long-term regeneration trajectory, continued support and enhancement of local cultural processes and structures, and highlighting community involvement and development are major factors to ensure the cultural sustainability of event.
In this paper, we investigate distributed secondary control of the inverter-based microgrid with its distributed generations (DGs) being interconnected through limited communication, namely, only ...quantized data can be transmitted among each pair of DGs at some time instants according to the event-triggered mechanism. We employ a framework of cyber-physical system (CPS) for newly developing the distributed control algorithms, which generate the distributed secondary control signals at the control layer as well as achieve the frequency and voltage restoration, and the optimal allocation of active power concurrently for all DGs at the physical layer. Also, the presented algorithms have the capability of excluding the Zeno behavior. The optimization action merely requires one controller designed for the derivative of active power to fulfill, no redundant control. Additionally, the presented algorithms are extended to the application with time-varying heterogeneous communication delays on the original basis, in which the negative effect of delays is well compensated by applying the Artstein model reduction method. Besides, the sufficient criteria on the control parameters for obtaining the aforementioned control and optimization goal are rigidly derived with the aid of the tools of nonsmooth analysis, Gronwall's inequality, and Lyapunov stability. Finally, several case studies and their results are presented to verify the effectiveness and superiority of the presented algorithms.
A common defect encountered in the spermatozoa of male infertility patients is an idiopathic failure of sperm-egg recognition. In order to resolve the molecular basis of this condition we have ...compared the proteomic profiles of spermatozoa exhibiting an impaired capacity for sperm-egg recognition with normal cells using label free mass spectrometry (MS)-based quantification. This analysis indicated that impaired sperm-zona binding was associated with reduced expression of the molecular chaperone, heat shock 70 kDa protein 2 (HSPA2), from the sperm proteome. Western blot analysis confirmed this observation in independent patients and demonstrated that the defect did not extend to other members of the HSP70 family. HSPA2 was present in the acrosomal domain of human spermatozoa as a major component of 5 large molecular mass complexes, the most dominant of which was found to contain HSPA2 in close association with just two other proteins, sperm adhesion molecule 1 (SPAM1) and arylsulfatase A (ARSA), both of which that have previously been implicated in sperm-egg interaction. The interaction between SPAM1, ARSA and HSPA2 in a multimeric complex mediating sperm-egg interaction, coupled with the complete failure of this process when HSPA2 is depleted in infertile patients, provides new insights into the mechanisms by which sperm function is impaired in cases of male infertility.
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•Ferrocene was included into cavity of cyclodextrin intercalated LDH by host-guest.•Host-guest interplay inhibited the low-temperature sublimation of ferrocene.•6 wt% LDH-CD@Ferr ...endowed epoxy resin with UL-94 V-1 and reduced heat release.•LDH-CD@Ferr reduced the total smoke production of epoxy resin remarkably.
Aiming to alleviate the low-temperature sublimation of ferrocene toward efficiently smoke-suppression epoxy resin (EP), the ferrocene molecule was inserted into the nanocavity of sulfonated cyclodextrin intercalated layered double hydroxide (LDH-CD) via host-guest chemistry. Adequate characterizations verified the targeted structure with one ferrocene molecule included into one cyclodextrin cavity. The resulting LDH-CD-Ferr formed a more uniform dispersion in EP matrix than LDH-CD. The comparative experiments demonstrated that 6 wt% LDH-CD-Ferr reduced the peak smoke production rate and total smoke production of EP matrix by 43% and 42% respectively due to the effectively shifted working temperature of ferrocene. The insightful mechanism investigation unveiled the condensed-phase behavior associated with higher-quality chars from catalytic charring reaction by retained ferrocene and the dominant vapor-phase behavior involved in the promoted combustion of smoke intermediate (soot). Additionally, 6 wt% LDH-CD-Ferr imparted EP matrix with increased limiting oxygen index (LOI) and reduced peak heat release rate by 5% and 36%. EP/6LDH-CD-Ferr was able to pass V-1 in UL-94 test relative to no rating of its counterparts. Also, in comparison to the simple mixture of LDH-CD and ferrocene, LDH-CD-Ferr presented the superiority in weakening the impact of ferrocene on the thermal stability of EP. In prospective, the host-guest chemistry offered an efficient approach to industrially utilizing ferrocene.
Multiferroics—materials that exhibit coupled ferroic orders—are considered to be one of the most promising candidate material systems for next‐generation spintronics, memory, low‐power ...nanoelectronics and so on. To advance potential applications, approaches that lead to persistent and extremely fast functional property changes are in demand. Herein, it is revealed that the phase transition and the correlated ferroic orders in multiferroic BiFeO3 (BFO) can be modulated via illumination of single short/ultrashort light pulses. Heat transport simulations and ultrafast optical pump‐probe spectroscopy reveal that the transient strain induced by light pulses plays a key role in determining the persistent final states. Having identified the diffusionless phase transformation features via scanning transmission electron microscopy, sequential laser pulse illumination is further demonstrated to perform large‐area phase and domain manipulation in a deterministic way. The work contributes to all‐optical and rapid nonvolatile control of multiferroicity, offering different routes while designing novel optoelectronics.
All‐optical manipulation of the complex phases and domain structures in multiferroic BiFeO3 thin films on ultrafast timescale is demonstrated by adoption of extremely short light pulses. The configuration of large‐area optically written domains can be controlled by tuning the competing elastic and electrostatic energies. These results offer a novel route for the development of all‐optical switchable devices and high‐speed multifunctional optoelectronics.
Motor imagery is based on the volitional modulation of sensorimotor rhythms (SMRs); however, the sensorimotor processes in patients with amyotrophic lateral sclerosis (ALS) are impaired, leading to ...degenerated motor imagery ability. Thus, motor imagery classification in ALS patients has been considered challenging in the brain-computer interface (BCI) community. In this study, we address this critical issue by introducing the Grassberger-Procaccia and Higuchi's methods to estimate the fractal dimensions (GPFD and HFD, respectively) of the electroencephalography (EEG) signals from ALS patients. Moreover, a Fisher's criterion-based channel selection strategy is proposed to automatically determine the best patient-dependent channel configuration from 30 EEG recording sites. An EEG data collection paradigm is designed to collect the EEG signal of resting state and the imagination of three movements, including right hand grasping (RH), left hand grasping (LH), and left foot stepping (LF). Five late-stage ALS patients without receiving any SMR training participated in this study. Experimental results show that the proposed GPFD feature is not only superior to the previously-used SMR features (mu and beta band powers of EEG from sensorimotor cortex) but also better than HFD. The accuracies achieved by the SMR features are not satisfactory (all lower than 80%) in all binary classification tasks, including RH imagery vs. resting, LH imagery vs. resting, and LF imagery vs. resting. For the discrimination between RH imagery and resting, the average accuracies of GPFD in 30-channel (without channel selection) and top-five-channel configurations are 95.25% and 93.50%, respectively. When using only one channel (the best channel among the 30), a high accuracy of 91.00% can still be achieved by the GPFD feature and a linear discriminant analysis (LDA) classifier. The results also demonstrate that the proposed Fisher's criterion-based channel selection is capable of removing a large amount of redundant and noisy EEG channels. The proposed GPFD feature extraction combined with the channel selection strategy can be used as the basis for further developing high-accuracy and high-usability motor imagery BCI systems from which the patients with ALS can really benefit.
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