Current approaches to fabrication of nSC composites for bone tissue engineering (BTE) have limited capacity to achieve uniform surface functionalization while replicating the complex architecture and ...bioactivity of native bone, compromising application of these nanocomposites for in situ bone regeneration. A robust biosilicification strategy is reported to impart a uniform and stable osteoinductive surface to porous collagen scaffolds. The resultant nSC composites possess a native‐bone‐like porous structure and a nanosilica coating. The osteoinductivity of the nSC scaffolds is strongly dependent on the surface roughness and silicon content in the silica coating. Notably, without the use of exogenous cells and growth factors (GFs), the nSC scaffolds induce successful repair of a critical‐sized calvarium defect in a rabbit model. It is revealed that topographic and chemical cues presented by nSC scaffolds could synergistically activate multiple signaling pathways related to mesenchymal stem cell recruitment and bone regeneration. Thus, this facile surface biosilicification approach could be valuable by enabling production of BTE scaffolds with large sizes, complex porous structures, and varied osteoinductivity. The nanosilica‐functionalized scaffolds can be implanted via a cell/GF‐free, one‐step surgery for in situ bone regeneration, thus demonstrating high potential for clinical translation in treatment of massive bone defects.
A biosilicification strategy is developed to provide a uniform and robust osteoinductive surface on porous natural collagen scaffolds. The resultant nanosilica–collagen (nSC) scaffolds possess topographical and chemical cues for superior in situ bone defect repair, without the use of exogenous cells or growth factors. This novel preparation of biomimetic bone scaffolds shows promising clinical applications in the treatment of bone defects.
The emergence of autonomous vehicles (AVs) is expected to revolutionize road transportation in the near future. Although large-scale numerical simulations and small-scale experiments have shown ...promising results, a comprehensive theoretical understanding to smooth traffic flow via AVs is lacking. In this article, from a control-theoretic perspective, we establish analytical results on the controllability, stabilizability, and reachability of a mixed traffic system consisting of human-driven vehicles and AVs in a ring road. We show that the mixed traffic system is not completely controllable, but is stabilizable, indicating that AVs can not only suppress unstable traffic waves but also guide the traffic flow to a higher speed. Accordingly, we establish the maximum traffic speed achievable via controlling AVs. Numerical results show that the traffic speed can be increased by over 6% when there are only 5% AVs. We also design an optimal control strategy for AVs to actively dampen undesirable perturbations. These theoretical findings validate the high potential of AVs to smooth traffic flow.
The development of the digital media environment has led to a diversification in the role of science communicators. Both scientists and non-scientist citizens can act as science communicators in ...relation to online discussion of genetically modified organisms (GMOs). Through a limited study, based on thematic and open coding of 60 answers provided by scientist science communicators and citizen science communicators on GMOs on Zhihu, the biggest Chinese knowledge sharing network, it has been found that “business conspiracy theories” about GMOs are the most mentioned and discussed theories, followed by the conspiracy theory of “GMOs as state control tool” on Zhihu. Both citizen science communicators and scientist science communicators are inclined to show oppositional attitudes to GMOs conspiracy theories on Zhihu, despite the differences in their scientific backgrounds; however, they use very different discourse strategies. Citizen science communicators tend to use “lay logic” with more rhetoric, while scientist science communicators tend to use direct scientific knowledge and logic with less rhetoric.
ZnO has long been considered as a promising candidate material for diluted magnetic semiconductors, owing to its theoretically predicted and experimentally observed above-room-temperature ...ferromagnetism and long spin-coherence time. In this brief perspective, recent progress in ZnO diluted magnetic semiconductors is reviewed with particular focus on three topics: (1) spin coherence in ZnO; (2) free-carrier type and concentration-dependent magnetic properties in ZnO; and (3) ferromagnetism in undoped and non-transition-metal-doped ZnO. Finally, current status and possible potential direction of research on ZnO diluted magnetic semiconductors are summarized in the concluding remarks.
•A personalized profile-based method to set zone-level HVAC start/stop schedules.•Personalized occupancy profile represents an occupant's long-term presence patterns.•An approach for reassigning ...occupants with similar presence patterns to same zones.•Quantitatively evaluates the coupled effects on energy efficiency.•Adopts a novel method for energy model calibration based on sensitivity analysis.
Buildings account for nearly 38% of the total energy use in the U.S., and 46% of this use is associated with commercial buildings. More than 40% of the energy in commercial buildings is consumed by HVAC systems, which provide heating, cooling and ventilation to individual zones to maintain comfortable and healthy indoor environments. A more refined control strategy based on actual occupancy might improve HVAC system related energy efficiency. Accurate occupancy profiles are important to determine actual energy demands and corresponding control schedules. This paper focuses on energy efficiency in office buildings with centrally controlled VAV systems by setting zone-level HVAC start/stop schedules using personalized occupancy profiles, which represent occupants’ long-term presence patterns. Evaluation of the method was performed using a simulation model, calibrated by the actual energy use data of an office test bed building. Up to 9% of the energy was saved when personalized occupancy profile based HVAC schedules were used. However, if occupants of a zone have different occupancy patterns, the aggregated patterns may hinder any potential efficiency that might be realized from zone-level HVAC start/stop schedules. This paper also presents an approach for reassigning rooms to unify the start/stop times at the zone level by placing occupants with similar profiles in the same mechanical zones. When room reassignment was implemented and coupled with profile based control schedule, HVAC energy use was reduced by another 8%. The proposed methods could provide reliable personalized HVAC control for small-size office buildings without advanced building automation systems, nevertheless, they could also be extended to buildings with packaged HVAC systems and individual air-conditioning systems.
Intelligence has been considered as the major challenge in promoting economic potential and production efficiency of precision agriculture. In order to apply advanced deep-learning technology to ...complete various agricultural tasks in online and offline ways, a large number of crop vision datasets with domain-specific annotation are urgently needed. To encourage further progress in challenging realistic agricultural conditions, we present the CropDeep species classification and detection dataset, consisting of 31,147 images with over 49,000 annotated instances from 31 different classes. In contrast to existing vision datasets, images were collected with different cameras and equipment in greenhouses, captured in a wide variety of situations. It features visually similar species and periodic changes with more representative annotations, which have supported a stronger benchmark for deep-learning-based classification and detection. To further verify the application prospect, we provide extensive baseline experiments using state-of-the-art deep-learning classification and detection models. Results show that current deep-learning-based methods achieve well performance in classification accuracy over 99%. While current deep-learning methods achieve only 92% detection accuracy, illustrating the difficulty of the dataset and improvement room of state-of-the-art deep-learning models when applied to crops production and management. Specifically, we suggest that the YOLOv3 network has good potential application in agricultural detection tasks.
China is characterized as ‘a large country with many smallholder farmers’ whose participation in modern agriculture is key to the country's modern agriculture development. Promoting smallholder ...farmers’ adoption of modern agricultural production technology is one effective way to improve the capabilities of smallholder farmers. This paper aims to explore the impact of Internet use on the adoption of agricultural production technology by smallholder farmers based on a survey of 1 449 smallholders across 14 provinces in China. The results suggest that Internet use can significantly promote technology adoption, with the probability of adopting new crop varieties, water-saving irrigation technology and straw-returning technology increasing by 0.200, 0.157 and 0.155, respectively. Furthermore, the effect of Internet use is found to be heterogeneous with a greater effect on smallholder farmers having low education levels, limited training, and high incomes. To increase agricultural production technology adoption by smallholders, rural Internet infrastructure and Internet use promotion should be the focus for the Chinese government.
Developing Type‐I photosensitizers is considered as an efficient approach to overcome the deficiency of traditional photodynamic therapy (PDT) for hypoxic tumors. However, it remains a challenge to ...design photosensitizers for generating reactive oxygen species by the Type‐I process. Herein, we report a series of α,β‐linked BODIPY dimers and a trimer that exclusively generate superoxide radical (O2−.) by the Type‐I process upon light irradiation. The triplet formation originates from an effective excited‐state relaxation from the initially populated singlet (S1) to triplet (T1) states via an intermediate triplet (T2) state. The low reduction potential and ultralong lifetime of the T1 state facilitate the efficient generation of O2−. by inter‐molecular charge transfer to molecular oxygen. The energy gap of T1‐S0 is smaller than that between 3O2 and 1O2 thereby precluding the generation of singlet oxygen by the Type‐II process. The trimer exhibits superior PDT performance under the hypoxic environment.
Heavy‐atom‐free boron dipyrromethene (BODIPY)‐based photosensitizers generate ROS exclusively by the Type‐I process upon near‐infrared light illumination for tumor ablation.
In this paper, a novel dynamic power allocation scheme is proposed to downlink and uplink non-orthogonal multiple access (NOMA) scenarios with two users for more flexibly meeting various quality of ...service requirements. The exact expressions for the outage probability and the average rate achieved by the proposed scheme, as well as their high signal-to-noise ratio approximations, are established. Compared with the existing works, such as NOMA with fixed power allocation and cognitive radio inspired NOMA, the proposed scheme can: 1) strictly guarantee a performance gain over conventional orthogonal multiple access; and 2) offer more flexibility to realize different tradeoffs between the user fairness and system throughput. Monte Carlo simulation results are provided to demonstrate the accuracy of the developed analytical results and the performance gain of the proposed power allocation scheme.
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