We propose a new method for reconstruction of sparse signals with and without noisy perturbations, termed the subspace pursuit algorithm. The algorithm has two important characteristics: low ...computational complexity, comparable to that of orthogonal matching pursuit techniques when applied to very sparse signals, and reconstruction accuracy of the same order as that of linear programming (LP) optimization methods. The presented analysis shows that in the noiseless setting, the proposed algorithm can exactly reconstruct arbitrary sparse signals provided that the sensing matrix satisfies the restricted isometry property with a constant parameter. In the noisy setting and in the case that the signal is not exactly sparse, it can be shown that the mean-squared error of the reconstruction is upper-bounded by constant multiples of the measurement and signal perturbation energies.
To avoid large open surgery using scaffold transplants, small‐sized cell carriers are employed to repair complexly shaped tissue defects. However, most cell carriers show poor cell adherences and ...viability. Therefore, polyhydroxyalkanoate (PHA), a natural biopolymer, is used to prepare highly open porous microspheres (OPMs) of 300–360 µm in diameter, combining the advantages of microspheres and scaffolds to serve as injectable carriers harboring proliferating stem cells. In addition to the convenient injection to a defected tissue, and in contrast to poor performances of OPMs made of polylactides (PLA OPMs) and traditional less porous hollow microspheres (PHA HMs), PHA OPMs present suitable surface pores of 10–60 µm and interconnected passages with an average size of 8.8 µm, leading to a high in vitro cell adhesion of 93.4%, continuous proliferation for 10 d and improved differentiation of human bone marrow mesenchymal stem cells (hMSCs). PHA OPMs also support stronger osteoblast‐regeneration compared with traditional PHA HMs, PLA OPMs, commercial hyaluronic acid hydrogels, and carrier‐free hMSCs in an ectopic bone‐formation mouse model. PHA OPMs protect cells against stresses during injection, allowing more living cells to proliferate and migrate to damaged tissues. They function like a micro‐Noah's Ark to safely transport cells to a defect tissue.
Combining the advantages of microspheres and scaffolds, highly open porous microspheres (OPMs) made of polyhydroxyalkanoate (PHA) are developed as injectable carriers harboring growing stem cells. The PHA OPMs protect the stem cells from stresses during injection, allowing more living cells to proliferate and migrate to damaged tissues, functioning like a micro‐Noah's Ark to safely transport cells to a designated tissue location for regeneration.
Lithium–sulfur (Li–S) battery system is endowed with tremendous energy density, resulting from the complex sulfur electrochemistry involving multielectron redox reactions and phase transformations. ...Originated from the slow redox kinetics of polysulfide intermediates, the flood of polysulfides in the batteries during cycling induced low sulfur utilization, severe polarization, low energy efficiency, deteriorated polysulfide shuttle, and short cycling life. Herein, sulfiphilic cobalt disulfide (CoS2) was incorporated into carbon/sulfur cathodes, introducing strong interaction between lithium polysulfides and CoS2 under working conditions. The interfaces between CoS2 and electrolyte served as strong adsorption and activation sites for polar polysulfides and therefore accelerated redox reactions of polysulfides. The high polysulfide reactivity not only guaranteed effective polarization mitigation and promoted energy efficiency by 10% but also promised high discharge capacity and stable cycling performance during 2000 cycles. A slow capacity decay rate of 0.034%/cycle at 2.0 C and a high initial capacity of 1368 mAh g–1 at 0.5 C were achieved. Since the propelling redox reaction is not limited to Li–S system, we foresee the reported strategy herein can be applied in other high-power devices through the systems with controllable redox reactions.
Microplastics (MPs) are emerging pollutants that act as a carrier of toxic pollutants, release toxic substances, and aggregate in biota. The adsorption behavior of MPs has recently become a research ...hot spot. The objective of this study was to summarize the main mechanisms by which MPs adsorb organic pollutants, introduce some mathematical models commonly used to study the adsorption behavior of MPs, and discuss the factors affecting the adsorption capacity from three perspectives, i.e., the properties of MPs and organic pollutants, and environmental factors. Adsorption kinetics and isothermal adsorption models are commonly used to study the adsorption of organic pollutants on MPs. We observed that hydrophobic interaction is the most common mechanism by which MPs adsorb organic pollutants, and also reportedly controls the portion of organic pollutants. Additionally, electrostatic interaction and other non-covalent forces, such as hydrogen bonds, halogen bonds, and π–π interactions, are also mechanisms of organic pollutant adsorption on MPs. The particle size, specific surface area, aging degree, crystallinity, and polarity of MPs, and organic pollutant properties (hydrophobicity and dissociated forms) are key factors affecting adsorption capacity. Changes in the pH, temperature, and ionic strength also affect the adsorption capacity. Current research on the adsorption behavior of MPs has mainly been conducted in laboratories, and in-depth studies on the adsorption mechanism and influencing factors are limited. Therefore, studies on the adsorption behavior of MPs in the environment are required, and this study will contribute to a better understanding of this topic.
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•This study reviews the mechanisms by which microplastics adsorb organic pollutants.•Factors affecting the adsorption capacity of microplastics are determined.•Microplastics adsorb organic pollutants mainly through hydrophobic interactions.•Microplastic and environmental properties affect adsorption of organic pollutants.
The financing of innovative entrepreneurial projects within colleges and universities presents a unique challenge due to the inherent risks associated with nascent ideas and the limitations of ...traditional funding channels. Blockchain technology, with its decentralized architecture and transparent ledger system, offers a promising solution to these challenges. By leveraging blockchain, academic institutions can enhance the efficiency, transparency, and accessibility of the financing process for entrepreneurial ventures. This paper explores the application of blockchain technology in the financing model of university-based entrepreneurial projects, examining its potential benefits, challenges, and implications. Through a comprehensive review of literature, case studies, and theoretical frameworks, we elucidate the mechanisms through which blockchain can facilitate funding, foster collaboration among stakeholders, and democratize access to capital. Moreover, we discuss the unique characteristics of blockchain technology and its alignment with the values and objectives of academic entrepreneurship. While blockchain holds immense potential to transform the financing landscape, its adoption also presents regulatory, scalability, and governance challenges that require careful consideration. By contributing to the discourse on blockchain, entrepreneur ship, and academia, this paper aims to inform policymakers, educators, and entrepreneurs about the transformative potential of blockchain in shaping the future of innovation and education.
Use of supersaturable formulations has been demonstrated as an effective approach to improve solubility and oral absorption of poorly water-soluble compounds. In supersaturable formulations, drug ...concentration exceeds the equilibrium solubility when the formulations are exposed to the gastrointestinal fluids and drug might precipitate before being absorbed, resulting in delayed response, and reduced efficacy or compromised bioavailability. Polymer based drug precipitation inhibitors have been used to inhibit or retard such precipitation. In this manner one can maintain a drug in the supersaturated concentration for an extended period of time, leading to significantly improved bioavailability of the poorly water-soluble drugs. This review article discusses different types of precipitation inhibitors, working hypotheses, and case studies with improved oral bioavailability.
Abstract
The frustrated magnet
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constitutes a fascinating quantum material platform that harbors the intriguing Kitaev physics. However, a consensus on its intricate spin interactions and ...field-induced quantum phases has not been reached yet. Here we exploit multiple state-of-the-art many-body methods and determine the microscopic spin model that quantitatively explains major observations in
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, including the zigzag order, double-peak specific heat, magnetic anisotropy, and the characteristic M-star dynamical spin structure, etc. According to our model simulations, the in-plane field drives the system into the polarized phase at about 7 T and a thermal fractionalization occurs at finite temperature, reconciling observations in different experiments. Under out-of-plane fields, the zigzag order is suppressed at 35 T, above which, and below a polarization field of 100 T level, there emerges a field-induced quantum spin liquid. The fractional entropy and algebraic low-temperature specific heat unveil the nature of a gapless spin liquid, which can be explored in high-field measurements on
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.
In this paper, the student documents are processed by experimental strategy, with the topic of college innovation and entrepreneurship resources recommendation, word diffusion and improved LDA topic ...model distribution training, set the training topic model and the number of topic top-words, and compare the high-frequency vocabulary and the probability distribution error of the 80% user coverage case and 90% user coverage case. Explore the stability of social media information pushing, the performance comparison results of both combine LDA based on user comment information text and LDA modeling directly using user comment information text as a reference. Select the experimental objects of innovation and entrepreneurship resources in colleges and universities, obtain the recommendation information of innovation and entrepreneurship resources in social media, and analyze the accuracy and satisfaction of algorithmic recommendation. Analyze the sharing characteristics of algorithmic recommendation information on social media and propose educational countermeasures against its adverse effects. According to the analysis, the improved LDA topic model results in a 15% and 85% increase in the number of same words in each topic when top_words is 10. When top_words is 20, the proportion of the same words in each theme is 15% and 78%, respectively. This indicates that the innovation and entrepreneurship education topic features are stable, and the accuracy and satisfaction of the algorithmic recommendation have improved.
Massive MIMO is a promising technique for future 5G communications due to its high spectrum and energy efficiency. To realize its potential performance gain, accurate channel estimation is essential. ...However, due to massive number of antennas at the base station (BS), the pilot overhead required by conventional channel estimation schemes will be unaffordable, especially for frequency division duplex (FDD) massive MIMO. To overcome this problem, we propose a structured compressive sensing (SCS)-based spatio-temporal joint channel estimation scheme to reduce the required pilot overhead, whereby the spatio-temporal common sparsity of delay-domain MIMO channels is leveraged. Particularly, we first propose the nonorthogonal pilots at the BS under the framework of CS theory to reduce the required pilot overhead. Then, an adaptive structured subspace pursuit (ASSP) algorithm at the user is proposed to jointly estimate channels associated with multiple OFDM symbols from the limited number of pilots, whereby the spatio-temporal common sparsity of MIMO channels is exploited to improve the channel estimation accuracy. Moreover, by exploiting the temporal channel correlation, we propose a space-time adaptive pilot scheme to further reduce the pilot overhead. Additionally, we discuss the proposed channel estimation scheme in multicell scenario. Simulation results demonstrate that the proposed scheme can accurately estimate channels with the reduced pilot overhead, and it is capable of approaching the optimal oracle least squares estimator.
Owing to the conversion chemistry of the sulfur cathode, the lithium–sulfur (Li–S) batteries exhibit high theoretical energy density. However, the intrinsic mobile redox centers during the ...sulfur/Li2S‐to‐lithium polysulfides solid‐to‐liquid phase transition induce low sulfur utilization and poor cycling life. Herein, the Janus separator of mesoporous cellular graphene framework (CGF)/polypropylene membrane to promote the utilization of sulfur cathode is introduced. The porous polypropylene membrane serves as an insulating substrate in contact with lithium anode while CGFs that possess high electrical conductivity of 100 S cm−1, a large mesopore volume of 3.1 cm3 g−1, and a huge surface area of 2120 m2 g−1 are adhered on cathode side to reactivate the shuttling‐back polysulfides and to preserve the ion channels. Therefore, the Li–S cell with the “two‐face” CGF Janus separator exhibit a high initial capacity of 1109 mAh g−1 and superior capacity preserved upon 800 mAh g−1 after 250 cycles at 0.2 C, which is 40% higher on sulfur utilization efficiency than the corresponding results with routine polypropylene separators. There are significant improvements on capacity as well as electrochemical kinetics. A very high areal capacity of 5.5 mAh cm−2 combined with high sulfur content of 80% and areal loading amount of 5.3 mg cm−2 is achieved for such advanced configuration. The negative impact of shuttle mechanism on lowering the utilization of sulfur and overall energy density of a Li–S battery is well eliminated by applying CGF separators. Consequently, employing carbonaceous materials as Janus face of separators enlightens new opportunities for improving the utilization of active materials and energy density of devices that involve complex phase evolution and conversion electrochemistry.
A Janus separator, fabricated from a polypropylene supported mesoporous cellular graphene framework, is developed to promote the utilization and stability of a sulfur cathode by reactivating the nonactive separator/cathode interphase. The Li–S battery with the “two‐face” Janus separator exhibits a 40% increase on capacity and stability, enlightening new opportunities for improving the utilization of migrated redox materials and the battery energy density.
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