Effects of four different drying methods on the colour, texture, sensory quality, microstructure, bacterial viability and storage stability of probiotic-enriched apple snacks were assessed. The ...drying methods were air drying （AD）, freeze drying （FD）, freeze drying followed by microwave vacuum drying （FD＋MVD） and air drying followed by explosion puffing drying （AD＋EPD）. Overall, FD＋MVD can be used as a suitable drying method for the development of probiotic enriched apple snacks in consideration of colour, texture, sensory quality, bacterial viability and storage stability. Probiotic bacteria in FD＋MVD-dried samples remained above 1×106 CFU g 1 for 120 days at 25℃C. Interestingly, bacterial viability in FD＋MVD-dried samples turned out to be significantly higher than FD-dried samples during storage for 120 days.
The recent developments of MOF-based materials, especailly their structure-property relationship for advanced electrochemical sensing applications are systematically summarized in this review. The ...different strategies used for the rational design and controllable synthesis of versatile MOF-based materials based on the specific requirements of the final electrochemical sensing applications are also outlined.
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•Recent development in MOF-based materials for electrochemical sensor is reviewed.•The structure-property relationship are emphasized.•Strategies for improving the sensing performance are discussed.•The current challenges and perspectives in this research area are also discussed.
Metal-organic frameworks (MOFs) are surprisingly porous materials that have attracted enormous attention in recent years owing to their fascinating structures and widespread potential applications. In this review, the recent developments of MOF-based materials for advanced electrochemical sensing applications are systematically summarized. A detailed discussion about the structure-property relationship, and the different strategies used for the rational design and controllable synthesis of versatile MOF-based materials based on the specific requirements of the final electrochemical sensing applications are outlined. The challenges and opportunities of developing MOF-based materials as novel electrochemical sensing platform are also discussed. Hopefully, this review will provide some creative inspiration to advance future studies on MOF-based materials in this emerging field.
Tin‐based perovskites with excellent optoelectronic properties and suitable band gaps are promising candidates for the preparation of efficient lead‐free perovskite solar cells (PSCs). However, it is ...challenging to prepare highly stable and efficient tin‐based PSCs because Sn2+ in perovskites can be easily oxidized to Sn4+ upon air exposure. Here we report the fabrication of air‐stable FASnI3 solar cells by introducing hydroxybenzene sulfonic acid or its salt as an antioxidant additive into the perovskite precursor solution along with excess SnCl2. The interaction between the sulfonate group and the Sn2+ ion enables the in situ encapsulation of the perovskite grains with a SnCl2–additive complex layer, which results in greatly enhanced oxidation stability of the perovskite film. The corresponding PSCs are able to maintain 80 % of the efficiency over 500 h upon air exposure without encapsulation, which is over ten times longer than the best result reported previously. Our results suggest a possible strategy for the future design of efficient and stable tin‐based PSCs.
Protective coating: A tin‐based perovskite solar cell with significantly improved stability to oxidation was prepared by introducing hydroxybenzene sulfonic acid or a salt thereof as an antioxidant additive into the perovskite precursor solution. The resulting perovskite grains are encapsulated by a SnCl2–additive complex layer.
2,5‐Furandicarboxylic acid (FDCA) is a bio‐based platform chemical for the production of polyethylene furanoate (PEF) and other valuable furanic chemicals. A magnetic laccase catalyst with ...(2,2,6,6‐tetramethyl‐piperidin‐1‐yl)oxyl (TEMPO) as the mediator has the remarkable capability of oxidizing 5‐hydroxymethylfurfural (HMF) to 2,5‐furandicarboxylic acid (FDCA). Under optimal reaction conditions, a quantitative yield (90.2 %) of FDCA with complete HMF conversion was obtained after 96 h of reaction. More importantly, the magnetic laccase catalyst exhibited good recyclability and stability, maintaining 84.8 % of its original activity following six reuse cycles. This is the first report on the efficient catalytic oxidation of HMF to FDCA by using an immobilized enzyme catalyst.
Cleaning up catalysis: There is a great need for the eco‐efficient and sustainable oxidation of bio‐based chemicals by using clean catalysts. In this study, magnetic laccase catalyst with TEMPO as the mediator showed high activity in the oxidation of 5‐hydroxymethylfurfural (HMF). Interesting and promising results were obtained, with 90.2 % yield of 2,5‐furandicarboxylic acid (FDCA) and complete HMF conversion.
In array processing, mutual coupling between sensors has an adverse effect on the estimation of parameters (e.g., DOA). While there are methods to counteract this through appropriate modeling and ...calibration, they are usually computationally expensive, and sensitive to model mismatch. On the other hand, sparse arrays, such as nested arrays, coprime arrays, and minimum redundancy arrays (MRAs), have reduced mutual coupling compared to uniform linear arrays (ULAs). With <inline-formula><tex-math notation="LaTeX">N</tex-math></inline-formula> denoting the number of sensors, these sparse arrays offer <inline-formula><tex-math notation="LaTeX">O({N}^{2})</tex-math></inline-formula> freedoms for source estimation because their difference coarrays have <inline-formula><tex-math notation="LaTeX"> O({N}^{2})</tex-math></inline-formula>-long ULA segments. But these well-known sparse arrays have disadvantages: MRAs do not have simple closed-form expressions for the array geometry; coprime arrays have holes in the coarray; and nested arrays contain a dense ULA in the physical array, resulting in significantly higher mutual coupling than coprime arrays and MRAs. This paper introduces a new array called the super nested array, which has all the good properties of the nested array, and at the same time achieves reduced mutual coupling. There is a systematic procedure to determine sensor locations. For fixed <inline-formula><tex-math notation="LaTeX">N</tex-math></inline-formula>, the super nested array has the same physical aperture, and the same hole-free coarray as does the nested array. But the number of sensor pairs with small separations (<inline-formula><tex-math notation="LaTeX">\lambda /2,2\times \lambda /2</tex-math></inline-formula>, etc.) is significantly reduced. Many theoretical properties are proved and simulations are included to demonstrate the superior performance of these arrays. In the companion paper, a further extension called the <inline-formula><tex-math notation="LaTeX">Q</tex-math></inline-formula>th-order super nested array is developed, which further reduces mutual coupling.
In the past several years, organic–inorganic hybrid perovskites and all inorganic perovskites have attracted enormous research interest in a variety of optoelectronic applications including solar ...cells, light‐emitting diodes, semiconductor lasers, and photodetectors for their plenty of appealing electrical and optoelectrical properties. Benefiting from the inherent amplification function of transistors and the pronounced photogating effect, perovskite‐based phototransistors and hybrid photodetectors can provide very high photoresponsivity and gain, rendering them highly promising for some specific applications especially ultrasensitive light detection. A review on the recent progress of phototransistors and hybrid photodetectors using perovskites as light‐sensitive materials is presented. The efforts and development in 3D and 2D perovskite‐based phototransistors, and perovskite/functional material (e.g., graphene, 2D semiconductors, organic semiconductors, and other semiconductors) heterojunction‐based hybrid photodetectors are introduced and discussed systematically. Some processing techniques for optimizing device performance are also addressed. In the final section, a conclusion of the research achievements is presented and possible challenges as well as outlook are provided to guide future activity in this research field.
Organic–inorganic hybrid perovskites and all inorganic perovskites are successfully used in phototransistors and hybrid photodetectors with very high photoresponsivity and gain. Herein, a review of the recent progress in phototransistors and hybrid photodetectors based on pure 3D and 2D perovskites, and perovskite/functional material heterojunctions is presented. A summary and outlook of this research field are also delivered.
In array processing, mutual coupling between sensors has an adverse effect on the estimation of parameters (e.g., DOA). Sparse arrays such as nested arrays, coprime arrays, and minimum redundancy ...arrays (MRA) have reduced mutual coupling compared to uniform linear arrays (ULAs). These arrays also have a difference coarray with O (N 2 ) virtual elements, where N is the number of physical sensors, and can therefore resolve O (N 2 ) uncorrelated source directions. But these well-known sparse arrays have disadvantages: MRAs do not have simple closed-form expressions for the array geometry; coprime arrays have holes in the coarray; and nested arrays contain a dense ULA in the physical array, resulting in significantly higher mutual coupling than coprime arrays and MRAs. In a companion paper, a sparse array configuration called the (second-order) super nested array was introduced, which has many of the advantages of these sparse arrays, while removing most of the disadvantages. Namely, the sensor locations are readily computed for any N (unlike MRAs), and the difference coarray is exactly that of a nested array, and therefore hole-free. At the same time, the mutual coupling is reduced significantly (unlike nested arrays). In this paper, a generalization of super nested arrays is introduced, called the Qth-order super nested array. This has all the properties of the second-order super nested array with the additional advantage that mutual coupling effects are further reduced for Q > 2. Many theoretical properties are proved and simulations are included to demonstrate the superior performance of these arrays.
Sparse arrays such as nested and coprime arrays use a technique called spatial smoothing in order to successfully perform MUSIC in the difference-coarray domain. In this paper it is shown that the ...spatial smoothing step is not necessary in the sense that the effect achieved by that step can be obtained more directly. In particular, with R̃ ss denoting the spatial smoothed matrix with finite snapshots, it is shown here that the noise eigenspace of this matrix can be directly obtained from another matrix R̃ which is much easier to compute from data.
In a heterogeneous cellular network (HetNet), consider that a base station in the HetNet is able to simultaneously schedule and serve K users in the downlink by performing the power-domain ...non-orthogonal multiple access (NOMA) scheme. This paper aims at the preliminary study on the downlink coverage and throughput performances of the HetNet with the non-coordinated NOMA and the proposed coordinated joint transmission NOMA (JT-NOMA) schemes. First, the coverage probability and link throughput of K users in each cell are studied and their accurate expressions are derived for the noncoordinated NOMA scheme in which no BSs are coordinated to jointly transmit the NOMA signals for a particular user. We show that the coverage and link throughput can be largely reduced if transmit power allocations among the K users do not satisfy the constraint derived. Next, we analyze the coverage and link throughput of K users for the coordinated JT-NOMA scheme in which the void BSs without users are coordinated to enhance the farthest NOMA user in a cell. The derived accurate results show that coordinated JT-NOMA can significantly improve the coverage and link throughput of all users. Finally, we show that there exist optimal power allocation schemes that maximize the average cell coverage and throughput under some derived power allocation constraints and numerical results validate our analytical findings.
The rice endosperm plays crucial roles in nourishing the embryo during embryogenesis and seed germination. Although previous studies have provided the general information about rice endosperm, a ...systematic investigation throughout the entire endosperm developmental process is still lacking. In this study, we examined in detail rice endosperm development on a daily basis throughout the 3o-day period of post-fertilization development. We observed that coenocytic nuclear division occurred in the first 2 days after pollination （DAP）, cellularization occurred between 3 and 5 DAP, differentiation of the aleurone and starchy endosperm occurred between 6 and 9 DAP, and accumulation of storage products occurred concurrently with the aleurone/starchy endosperm differentiation from 6 DAP onwards and was accomplished by 21 DAP. Changes in cytoplasmic membrane permeability, possibly caused by programmed cell death, were observed in the central region of the starchy endosperm at 8 DAP, and expanded to the whole starchy endosperm at 21 DAP when the aleurone is the only living component in the endosperm. Further, we observed that a distinct multi-layered dorsal aleurone formed near the dorsal vascular bundle, while the single- or occasionally two-cell layered aleurone was located in the lateral and ventral positions of endosperm. Our results provide in detail the dynamic changes in mitotic divisions, cellularization, cell differentiation, storage product accumulation, and programmed cell death that occur during rice endosperm development.
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