Controlled Synthesis of Hierarchically Assembled Porous ZnO Microspheres with Enhanced Gas-Sensing Properties

The ZnO microspheres constructed by porous nanosheets were successfully synthesized by calcinating zinc hydroxide carbonate (ZHC) microspheres obtained by a sample hydrothermal method. The samples were characterized in detail with scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and thermogravimetric and differential scanning calorimetry (TG-DSC). The results indicated that the prepared ZnO microspheres were well crystalline with wurtzite hexagonal phase. The effects of reaction time, temperature, the amount of trisodium citrate, and urea on the morphology of ZnO microspheres were studied. The formation mechanism of porous ZnO microspheres was discussed. Furthermore, the gas-sensing properties for detection of organic gas of the prepared porous ZnO microspheres were investigated. The results indicated that the prepared porous ZnO microspheres exhibited high gas-sensing properties for detection of ethanol gas

Application of symmetric orthogonal multiwavelets and prefilter technique for image compression

Multiwavelets are new addition to the body of wavelet theory. There are many types of symmetric multiwavelets such as Geronimo-Hardin-Massopust (GHM) and Chui-Lian (CL) multiwavelets. However, the matrix filter generating the GHM system multiwavelets does not satisfy the symmetric property. For this reason, this paper presents a new method to construct the symmetric orthogonal matrix filter, which leads to the symmetric orthogonal multiwavelets (SOM). Moreover, we analyze the prefilter technique, corresponding to the symmetric orthogonal matrix filter, to get a good combining frequency response. To prove the good property of SOM in image compression application, we compared the compression effect with other writers' work, which was in published literature.Facultad de Informátic

Mulberry leaf lipid nanoparticles: a naturally targeted CRISPR/Cas9 oral delivery platform for alleviation of colon diseases

Oral treatment of colon diseases with the CRISPR/Cas9 system has been hampered by the lack of a safe and efficient delivery platform. Overexpressed CD98 plays a crucial role in the progression of ulcerative colitis (UC) and colitis-associated colorectal cancer (CAC). In this study, lipid nanoparticles (LNPs) derived from mulberry leaves are functionalized with Pluronic copolymers and optimized to deliver the CRISPR/Cas gene editing machinery for CD98 knockdown. The obtained LNPs possessed a hydrodynamic diameter of 267.2 nm, a narrow size distribution, and a negative surface charge (â 25.6 mV). Incorporating Pluronic F127 into LNPs improved their stability in the gastrointestinal tract and facilitated their penetration through the colonic mucus barrier. The galactose end groups promoted endocytosis of the LNPs by macrophages via asialoglycoprotein receptor-mediated endocytosis, with a transfection efficiency of 2.2-fold higher than Lipofectamine 6000. The LNPs significantly decreased CD98 expression, down-regulated pro-inflammatory cytokines (TNF-α and IL-6), up-regulated anti-inflammatory factors (IL-10), and polarized macrophages to M2 phenotype. Oral administration of LNPs mitigated UC and CAC by alleviating inflammation, restoring the colonic barrier, and modulating intestinal microbiota. As the first oral CRISPR/Cas9 delivery LNP, this system offers a precise and efficient platform for the oral treatment of colon diseases.This study was supported by the National Natural Science Foundation of China (82072060, 82360110, and 22008201), the Science and Technology Department of Jiangxi Province (20212BDH81019 and 20224BAB206073), the Fundamental Research Funds for the Central Universities (SWU-XDPY22006 and SWU-KQ22075), the Venture & Innovation Support Pro-gram for Chongqing Overseas Returnees (2205012980212766), and theScience Fund for Distinguished Young Scholars of Chongqing Municipality (2022NSCQ-JQX5279)

How to Design Your Project in the Online Crowdfunding Market? Evidence from Kickstarter

Raising money in the online crowdfunding market is an important way for start-up enterprises to start their entrepreneurial projects. However, how to help creators design their projects in this market is still an open and very realistic issue. In this study, we collect a unique dataset from Kickstarter (a leading crowdfunding platform in the U.S.) to examine the impacts of reward scheme related and unrelated factors on projects’ crowdfunding performance based on solid theories. We use a Heteroscedasticity-based instrument method to solve the endogeneity of backing price. We found that a project creator can raise more money in the crowdfunding market if he/she sets a bit higher maximum backing price; lists relative fewer reward tiers in their reward schemes; publishes well designed project homepage; and communicates with backers as much as possible during the project’s survival time. We also discuss the implications for project design in this market

A review of accelerated conditioning for a polymer electrolyte membrane fuel cell

A newly fabricated polymer electrolyte membrane (PEM) fuel cell usually needs a so-called breakin/conditioning/incubation period to activate it and reach its best performance. Typically, during this activation period the cell performance increases gradually, and then reaches a plateau without further increase. Depending on the membrane electrode assemblies, this process can take hours and even days to complete, which consumes a considerable amount of hydrogen fuel, leading to a higher operating cost. To provide for accelerated conditioning techniques that can complete the process in a short time period, this paper reviews established conditioning protocols and reported methods to condition PEM single cells and stacks, in an attempt to summarize available information on PEM fuel cell conditioning and the underlying mechanisms. Various techniques are arranged into two categories: on-line conditioning and off-line conditioning. For each technique, the experimental procedure and outcomes are outlined. Finally, weaknesses of the currently used conditioning techniques are indicated and further research efforts are proposed.Peer reviewed: YesNRC publication: Ye

A review of polymer electrolyte membrane fuel cell durability test protocols

Durability is one of the major barriers to polymer electrolyte membrane fuel cells (PEMFCs) being accepted as a commercially viable product. It is therefore important to understand their degradation phenomena and analyze degradation mechanisms from the component level to the cell and stack level so that novel component materials can be developed and novel designs for cells/stacks can be achieved to mitigate insufficient fuel cell durability. It is generally impractical and costly to operate a fuel cell under its normal conditions for several thousand hours, so accelerated test methods are preferred to facilitate rapid learning about key durability issues. Based on the US Department of Energy (DOE) and US Fuel Cell Council (USFCC) accelerated test protocols, as well as degradation tests performed by researchers and published in the literature, we review degradation test protocols at both component and cell/stack levels (driving cycles), aiming to gather the available information on accelerated test methods and degradation test protocols for PEMFCs, and thereby provide practitioners with a useful toolbox to study durability issues. These protocols help prevent the prolonged test periods and high costs associated with real lifetime tests, assess the performance and durability of PEMFC components, and ensure that the generated data can be compared.Peer reviewed: YesNRC publication: Ye

Effects of One-Year Simulated Nitrogen and Acid Deposition on Soil Respiration in a Subtropical Plantation in China

Atmospheric nitrogen (N) and acid deposition have become global environmental issues and are likely to alter soil respiration (Rs); the largest CO2 source is from soil to the atmosphere. However, to date, much less attention has been focused on the interactive effects and underlying mechanisms of N and acid deposition on Rs, especially for ecosystems that are simultaneously subjected to elevated levels of deposition of both N and acid. Here, to examine the effects of N addition, acid addition, and their interactions with Rs, we conducted a two-way factorial N addition (control, CK; 60 kg N ha−1 a−1, LN; 120 kg N ha−1 a−1, HN) and acid addition (control, CK; pH 4.5, LA; pH 2.5, HA) field experiment in a subtropical plantation in China. Our results showed the following: (1) During the one-year observation period, the seasonal dynamics of Rs presented a single peak curve model, which was closely related to the surface soil temperature. (2) The simulated N deposition and acid deposition significantly decreased the Rs in the subtropical plantation. Compared to the CK plots, the LN and HN treatments reduced the annual mean values of Rs by 41% and 56%, and the annual mean values of Rs were inhibited by 26% and 31% in the LA and HA plots. The inhibition of N application on Rs was stronger than that of the simulated acid deposition. (3) Significant interactions between N addition and acid addition on Rs were detected, and Rs was significantly inhibited under four co-addition treatments. (4) The underlying mechanism and main reason for the responses of Rs to simulated N and acid deposition in this study might be the inhibition of soil microbial biomass and soil enzyme activity due to soil acidification under increased N and acid input

A stochastic analysis of the energy and reserve operation for battery storage-assisted prosumer aggregator in the Southwest Power Pool Market

To facilitate the integration of renewable energy in electric power systems, the installed capacity of distributed renewable energy sources has been increased rapidly worldwide in recent years, and the prosumers and prosumer aggregators have become important players in smart grid. To maximize the economic benefits of a prosumer aggregator in power markets, a stochastic model used for generating the day-ahead (DA) energy and operating reserve scheduling strategies is proposed. The uncertainties associated with solar power productions, demands and prices in energy and operating reserve markets are handled via stochastic optimization technique. To manage the potential risks faced by the prosumer aggregator, the conditional value at risk is adopted to measure and manage its potential low profits or losses. Finally, case studies are performed by using the data in the energy and operating reserve markets operated by the Southwest Power Pool (SPP), and the optimal energy and operating reserve bids are generated effectively by solving the proposed model. The values of the operating reserve markets and battery storages are analyzed in detail via simulation, and it shows that higher reserve prices and larger battery storage capacity would lead to higher expected profit and lower risks for the prosumer aggregator