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Temperature plays a critical role in the efficiency and stability of industrial wastewater treatment plants (WWTPs). This study focuses on the effects of temperature on activated sludge (AS) communities within the A2O process of 19 industrial WWTPs in the Yangtze River Delta, a key industrial region in China. The investigation aims to understand how temperature influences AS community composition, functional assembly, and carbon transformation processes, including CO2 emission potential. Our findings reveal that increased operating temperatures lead to a decrease in alpha diversity, simplifying community structure and increasing modularity. Dominant species become more prevalent, with significant decreases in the relative abundance of Chloroflexi and Actinobacteria, and increases in Bacteroidetes and Firmicutes. Moreover, higher temperatures enhance the overall carbon conversion potential of AS, particularly boosting CO2 absorption in anaerobic conditions as the potential for CO2 emission during glycolysis and TCA cycles grows and diminishes, respectively. The study highlights that temperature is a major factor affecting microbial community characteristics and CO2 fluxes, with more pronounced effects observed in anaerobic sludge. This study provides valuable insights for maintaining stable A2O system operations, understanding carbon footprints, and improving COD removal efficiency in industrial WWTPs.

Aqueous zinc ions lower the corrosion rate of Alloy 600, which helps lower the radiation dose rate in pressurized water reactors (PWRs). The influence of zinc on the electrochemical behavior of Alloy 600 in PWR primary water (PW) at 320 °C was investigated using a combination of electron microscopy and electrochemical impedance spectroscopy (EIS). Secondary electron microscopy (SEM) and scanning transmission electron microscopy (STEM)/energy-dispersive X-ray spectroscopy (EDS) indicated duplex surface films were formed on the Alloy 600 in PWR PW with and without 100 ppb of zinc. There was no effect of zinc on the chromium-rich inner layer (IL) (of Cr2O3 and/or CrOOH). Zinc had a significant effect on the outer layer (OL). In the absence of zinc, a highly porous OL formed that was mostly composed of nickel oxide whiskers. In the presence of zinc, a zinc-containing, denser OL of oxide was formed. The EIS data were acquired in laboratory simulated PWR PW at 320 °C with and without 100 ppb zinc. The spectra were measured at nine different values of potential that spanned a 500 mV-wide range. The EIS indicated there was no effect of zinc on the oxidation rate of metals at the alloy/IL interface nor on the transport of ions through the IL. Zinc lowered the corrosion rate because the dense OL inhibited the release of nickel ions from the IL into the solution.

Background: Externalizing problems, internalizing problems, and obesity are among the greatest challenges to adolescent health. However, the moderating and mediating mechanisms that underlie this association remain predominantly unexplored. Objectives: In this study, we examined the association between body mass index (BMI) and externalizing and internalizing scores in adolescents, tested whether traditional bullying and cyberbullying mediated the association, and explored the moderated role of sex. Methods: The data came from 1486 adolescents from grade 7, 8, and 10 living in Shantou, China. Information on BMI, traditional bullying, and cyberbullying victimization was obtained through a self-administered questionnaire. The students’ externalizing and internalizing scores were evaluated using the Strengths and Difficulties Questionnaire (SDQ). Furthermore, we built two parallel mediation models with sex as a moderating variable. Results: Compared to their peers with normal weight, adolescents with increased BMI reported higher externalizing and internalizing scores. Traditional bullying and cyberbullying were both significant mediators in the two relationships. Sex moderated the pathway from BMI to cyberbullying. But sex did not moderate the relationship between BMI and traditional bullying. Conclusions: The results highlight that it is imperative for educators to identify students who are subjected to weight-based bullying and provide them with recommendations for effective coping strategies. Meanwhile, both victims of traditional bullying and those affected by cyberbullying should be the focus of prevention and intervention efforts when developing a strategy to improve levels of internalizing and externalizing symptoms among adolescents with increased BMI.

In this study, a halotolerant yeast that is capable of efficiently decolorizing and detoxifying azo dyes was isolated, identified and characterized for coping with the treatment of azo-dye-containing wastewaters. A characterization of the yeast, including the optimization of its metabolism and growth conditions, its detoxification effectiveness and the degradation pathway of the target azo dye, as well as a determination of the key activities of the enzyme, was performed. Finally, the possible halotolerance mechanisms of the yeast were proposed through a comparative transcriptome analysis. The results show that a halotolerant yeast, A4, which could decolorize various azo dyes, was isolated from a marine environment and was identified as Meyerozyma guilliermondii. Its optimal conditions for dye decolorization were ≥1.0 g/L of sucrose, ≥0.2 g/L of (NH4)2SO4, 0.06 g/L of yeast extract, pH 6.0, a temperature of 35 °C and a rotation speed of ≥160 rpm. The yeast, A4, degraded and detoxified ARB through a series of steps, relying on the key enzymes that might be involved in the degradation of azo dye and aromatic compounds. The halotolerance of the yeast, A4, was mainly related to the regulation of the cell wall components and the excessive uptake of Na+/K+ and/or compatible organic solutes into the cells under different salinity conditions. The up-regulation of genes encoding Ca2+-ATPase and casein kinase II as well as the enrichment of KEGG pathways associated with proteasome and ribosome might also be responsible for its halotolerance.

Phosphorus utilization by crop plants is often limited, thereby resulting in large accumulations of residual phosphorus fertilizer in the soil. Trichoderma fungi function as natural decomposition agents that can contribute to increasing decomposition and promoting nutrient absorption in plants. In this study, we developed a novel fertilizer application strategy that reduces phosphate fertilizer and increases Trichoderma and examined its effects on the growth, nutrient absorption, and fruit quality of pepper (Capsicum annuum L.). We compared the efficacies of eight treatments: P100 = standard dose application of phosphorus fertilizer; P85 = 85% dose; P70 = 70% dose; P0 = no phosphorus fertilizer; and the TP100, TP85, TP70, and TP0 treatments, in which a Trichoderma mixture was added to the P100, P85, P70, and P0 treatments, respectively. The combined fertilizer application strategy stimulated plant growth, increased chlorophyll content, improved yield, and enhanced nutrient absorption. Additionally, the strategy improved pepper fruit quality by increasing the contents of soluble proteins, soluble sugars, vitamin C, capsaicin, and capsanthin. A comprehensive analysis indicated that the TP85 treatment was the optimal fertilization regime for pepper. This study provides a novel fertilizer application strategy for pepper that not only ensures good plant growth but also protects soil health.

The rapid development of intelligent connected vehicles has increased the attack surface of vehicles and made the complexity of vehicle systems unprecedented. Original equipment manufacturers (OEMs) need to accurately represent and identify threats and match corresponding security requirements. Meanwhile, the fast iteration cycle of modern vehicles requires development engineers to quickly obtain cybersecurity requirements for new features in their developed systems in order to develop system code that meets cybersecurity requirements. However, existing threat identification and cybersecurity requirement methods in the automotive domain cannot accurately describe and identify threats for a new feature while also quickly matching appropriate cybersecurity requirements. This article proposes a cybersecurity requirements management system (CRMS) framework to assist OEM security experts in conducting comprehensive automated threat analysis and risk assessment and to help development engineers identify security requirements prior to software development. The proposed CRMS framework enables development engineers to quickly model their systems using the UML-based (i.e., capable of describing systems using UML) Eclipse Modeling Framework and security experts to integrate their security experience into a threat library and security requirement library expressed in Alloy formal language. In order to ensure accurate matching between the two, a middleware communication framework called the component channel messaging and interface (CCMI) framework, specifically designed for the automotive domain, is proposed. The CCMI communication framework enables the fast model of development engineers to match with the formal model of security experts for threat and security requirement matching, achieving accurate and automated threat and risk identification and security requirement matching. To validate our work, we conducted experiments on the proposed framework and compared the results with the HEAVENS approach. The results showed that the proposed framework is superior in terms of threat detection rates and coverage rates of security requirements. Moreover, it also saves analysis time for large and complex systems, and the cost-saving effect becomes more pronounced with increasing system complexity.

Background and aim: Diagnosing nonalcoholic steatohepatitis (NASH) is challenging. This study intended to explore the diagnostic value of multiple technical acoustic measurements in the diagnosis of NASH, and to establish a diagnostic model combining technical acoustic measurements with clinical parameters to improve the diagnostic efficacy of NASH. Methods: We consecutively enrolled 75 patients with clinically suspected nonalcoholic fatty liver disease (NAFLD) who underwent percutaneous liver biopsy in our hospital from June 2020 to December 2021. All cases underwent multiple advanced acoustic measurements for liver such as shear wave dispersion (SWD), shear wave speed (SWS), attenuation imaging (ATI), normalized local variance (NLV), and liver–kidney intensity ratio (Ratio) examination before liver biopsies. A nomogram prediction model combining the technical acoustic measurements and clinical parameters was established and the model is proposed to improve the diagnostic performance of NASH. Results: A total of 75 cases were included in this study. The classification of pathological grade for NASH was as follows: normal liver, (n = 15, 20%), nonalcoholic fatty liver (NAFL), (n = 44, 58.7%), and NASH, (n = 16, 21.3%). There were statistically significant differences in SWS (p = 0.002), acoustic coefficient (AC) (p = 0.018), NLV (p = 0.033), age (p = 0.013) and fasting blood glucose (Glu) (p = 0.049) between NASH and non-NASH. A nomogram model which includes SWS, AC, NLV, age and Glu was built to predict NASH, and the calibration curves showed good calibrations in both training and validation sets. The AUCs of the combined nomogram model for the training set and validation set were 0.8597 and 0.7794, respectively. Conclusion: There were statistically significant differences in SWS, AC, NLV, age and Glu between NASH and non-NASH. A nomogram model which includes SWS, AC, NLV, age and Glu was built to predict NASH. The predictive model has a higher diagnostic performance than a single factor model in the diagnosis of NASH and has good clinical application prospects.

Compared with thrombus dissolution using only thrombolytic agents, an advanced therapy of direct stirring of the blood clot can yield shorter recanalization time and higher recanalization velocity. Our previous research presented the design of a novel micro-stirrer, which can convert longitudinal vibration into transverse vibration and eventually generate opposite transverse vibration at the end-effort, like a scissor, for efficient blood clot stirring and thrombus dissolution acceleration. Transverse vibration is the most effective movement to dissolve thrombi. However, the small size of blood vessels has strict limits, which will greatly affect the output transverse vibration. Therefore, to improve the output performance of the micro-stirrer in curved and narrow vascular spaces, the analysis and structure optimization of the micro-stirrer is expected to increase the vibration mode conversion efficiency from longitudinal to transverse mode. The design concept and theoretical analysis of the micro-stirrer are presented in detail. Aiming to obtain the optimal structure parameters of the micro-stirrer, the mathematical model is established and analyzed. Next, a series of finite element models involving important structure parameters are designed and investigated. Finally, the optimal structure parameters are obtained, and the stirring effect in a blood vessel is verified by simulation and experiment.

Modern vehicles are more complex and interconnected than ever before, which also means that attack surfaces for vehicles have increased significantly. Malicious cyberattacks will not only exploit personal privacy and property, but also affect the functional safety of electrical/electronic (E/E) safety-critical systems by controlling the driving functionality, which is life-threatening. Therefore, it is necessary to conduct cybersecurity testing on vehicles to reveal and address relevant security threats and vulnerabilities. Cybersecurity standards and regulations issued in recent years, such as ISO/SAE 21434 and UNECE WP.29 regulations (R155 and R156), also emphasize the indispensability of cybersecurity verification and validation in the development lifecycle but lack specific technical details. Thus, this paper conducts a systematic and comprehensive review of the research and practice in the field of automotive cybersecurity testing, which can provide reference and advice for automotive security researchers and testers. We classify and discuss the security testing methods and testbeds in automotive engineering. Furthermore, we identify gaps and limitations in existing research and point out future challenges.

Chrysanthemum is a popular ornamental plant with a long history of cultivation. Both the leaf and flowerhead of Chrysanthemum are known to produce diverse secondary metabolites, particularly terpenoids. Here we aimed to determine the relationship between terpene chemistry and the trichome traits in Chrysanthemum. In our examination of three cultivars of C. morifilium and three accessions of C. indicum, all plants contained T-shaped trichomes and biseriate peltate glandular trichomes. The biseriate peltate glandular trichome contained two basal cells, two stalk cells, six secondary cells and a subcuticular space, while the non-glandular T-shaped trichome was only composed of stalk cells and elongated cells. Histochemical staining analysis indicated that the biseriate peltate glandular trichome contained terpenoids and lipid oil droplets but not the T-shaped trichome. Next, experiments were performed to determine the relationship between the accumulation and emission of the volatile terpenoids and the density of trichomes on the leaves and flowerheads in all six Chrysanthemum cultivars\accessions. A significant correlation was identified between the monoterpenoid and sesquiterpenoid content and the density of glandular trichomes on the leaves, with the correlation coefficients being 0.88, 0.86 and 0.90, respectively. In contrast, there was no significant correlation between the volatile terpenoid content and the density of T-shaped trichomes on the leaves. In flowerheads, a significant correlation was identified between the emission rate of terpenoids and the number of glandular trichomes on the disc florets, with a correlation coefficient of 0.95. Interestingly, the correlation between the density of glandular trichomes and concentrations of terpenoids was insignificant. In summary, the relationship between trichomes and terpenoid chemistry in Chrysanthemum is clearly established. Such knowledge may be helpful for breeding aromatic Chrysanthemum cultivars by modulating the trichome trait.

Leaf mechanical wounding triggers a rapid release—within minutes—of a blend of volatile organic compounds. A wounding-induced VOC blend is mainly composed of oxygenated ubiquitous stress volatiles such as methanol and volatile products of lipoxygenase (LOX) pathway (mainly C5 and C6 alcohols and aldehydes and their derivatives), but also includes multiple minor VOCs that collectively act as infochemicals, inducing defences in non-damaged plant leaves and neighbouring plants and attracting herbivore enemies. At present, the interspecific variability of the rate of induction and magnitude of wounding-induced emissions and the extent to which plant structural traits and physiological activity alter these emissions are poorly known. Particularly scarce is information on the induced emissions in tropical agricultural plant species, despite their economic importance and large area of cultivation at regional and global scales. We chose five tropical crops with varying photosynthetic activity and leaf structural characteristics—Abelmoschus esculentus, Amaranthus cruentus, Amaranthus hybridus, Solanum aethiopicum, and Telfairia occidentalis—to characterize the kinetics and magnitude of wounding-induced emissions, hypothesizing that the induced emission response is greater and faster in physiologically more active species with greater photosynthetic activity than in less active species. Rapid highly repeatable leaf wounds (12 mm cuts) were generated by a within-leaf-chamber cutting knife. Wounding-induced VOC emissions were measured continuously with a proton-transfer reaction time-of-flight mass spectrometer and gas-chromatography mass spectrometry was used to separate isomers. Twenty-three ion VOCs and twelve terpenoid molecule structures were identified, whereas ubiquitous stress volatiles methanol (on average 40% of total emissions), hexenal (24%), and acetaldehyde (11%) were the main compounds across the species. Emissions of low-weight oxygenated compounds (LOC, 70% of total) and LOX products (29%) were positively correlated across species, but minor VOC components, monoterpenoids and benzenoids, were negatively correlated with LOC and LOX, indicating a reverse relationship between signal specificity and strength. There was a large interspecific variability in the rate of induction and emission magnitude, but the hypothesis of a stronger emission response in physiologically more active species was only partly supported. In addition, the overall emission levels were somewhat lower with different emission blend compared to the data reported for wild species, as well as different shares for the VOCs in the blend. The study demonstrates that wounding-dependent emissions from tropical agricultural crops can significantly contribute to atmospheric volatiles, and these emissions cannot be predicted based on current evidence of wild plant model systems.

This research aims to understand the precise intracellular metabolic processes of how microbes solubilize insoluble phosphorus (Insol-P) to increase bio-available P. Newly isolated Penicillium oxalicum PSF-4 exhibited outstanding tricalcium phosphate (TP) and iron phosphate (IP) solubilization performance—as manifested by microbial growth and the secretion of low-molecular-weight organic acids (LMWOAs). Untargeted metabolomics approach was employed to assess the metabolic alterations of 73 intracellular metabolites induced by TP and IP compared with soluble KH2PO4 in P. oxalicum. Based on the changes of intracellular metabolites, it was concluded that (i) the enhanced intracellular glyoxylate and carbohydrate metabolisms increased the extracellular LMWOAs production; (ii) the exposure of Insol-P poses potential effects to P. oxalicum in destructing essential cellular functions, affecting microbial growth, and disrupting amino acid, lipid, and nucleotide metabolisms; and (iii) the intracellular amino acid utilization played a significant role to stimulate microbial growth and the extracellular LMWOAs biosynthesis.

Selection signature provides an efficient tool to explore genes related to traits of interest. In this study, 176 ewes from one Chinese uniparous breed and three Kazakhstan multiparous breeds are genotyped using Affymetrix 600K HD single nucleotide polymorphism (SNP) arrays, F-statistics (Fst), and a Cross Population Extend Haplotype Homozygosity Test (XPEHH). These are conducted to identify genomic regions that might be under selection in three population pairs comprised the one multiparous breed and the uniparous breed. A total of 177 and 3072 common selective signatures were identified by Fst and XPEHH test, respectively. Nearly half of the common signatures detected by Fst were also captured by XPEHH test. In addition, 1337 positive and 1735 common negative signatures were observed by XPEHH in three Kazakhstan multiparous breeds. In total, 242 and 798 genes were identified in selective regions and positive selective regions identified by Fst and XPEHH, respectively. These genes were further clustered in 50 gene ontology (GO) functional terms and 66 Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways in enrichment analysis. The GO terms and pathways were relevant with reproductive processes, e.g., oxytocin signaling pathway, thyroid hormone synthesis and GnRH signaling pathway, vascular smooth muscle contraction and lipid metabolism (alpha-Linolenic acid metabolism and Linoleic acid metabolism), etc. Based on the findings, six potential candidate genes ESR1, OXTR, MAPK1, RYR1, PDIA4, and CYP19A1, under positive selection related to characteristics of multiparous sheep breeds were revealed. Our results improve our understanding of the mechanisms of selection that underlies the prolificacy trait in sheep, and provide essential references for future sheep breeding.

Clematis florida is a popular ornamental vine species known for diverse colors and shapes of its flowers but not for scent. Here we investigated the composition and biosynthesis of floral scent in ‘Kaiser’, a fragrant cultivar of C. florida that has sterile flowers. Volatile profiling revealed that flowers of ‘Kaiser’ emit more than 20 compounds, with monoterpenes being most abundant. Among the three floral organs, namely sepals, transformed-petals, and ovaries, ovaries had the highest rates of total volatile emission. To determine the molecular mechanism underlying floral scent biosynthesis in ‘Kaiser’, we sequenced a flower transcriptome and searched the transcriptome for terpene synthase genes (TPSs), which are key genes for terpene biosynthesis. Among the TPS genes identified, three were putative intact full-length genes and were designated CfTPS1, CfTPS2, and CfTPS3. Phylogenetic analysis placed CfTPS1, CfTPS2, and CfTPS3 to the TPS-g, TPS-b, and TPS-a subfamily, respectively. Through in vitro enzyme assays with Escherichia coli-expressed recombinant proteins, both CfTPS1 and CfTPS2 were demonstrated to catalyze the conversion of geranyl diphosphate to linalool, the most abundant constituent of C. florida floral scent. In addition, CfTPS1 and CfTPS2 produced the sesquiterpene nerolidol from (E,E)-farnesyl diphosphate. CfTPS3 showed sesquiterpene synthase activity and produced multiple products in vitro. All three CfTPS genes showed higher levels of expression in sepals than those in transformed-petals and ovaries. Our results show that despite being sterile, the flowers of ‘Kaiser’ have normal mechanisms for floral scent biosynthesis that make the flowers fragrant.

Roots provide anchorage and enable the absorption of water and micronutrients from the soil for plants. Besides these essential functions, roots are increasingly being recognized as an important organ for the production of diverse secondary metabolites. The goal of this study was to investigate the chemical composition and function of terpenoid secondary metabolites in roots of different cultivars of the popular ornamental plant Chrysanthemum morifolium Ramat. Although C. morifolium is known for rich production of secondary metabolites in its flower heads and leaves, the diversity of secondary metabolites in roots remains poorly characterized. In this study, 12 cultivars of C. morifolium were selected for comparative analysis. From their roots, a total of 20 terpenoids were detected, including four monoterpenes, 15 sesquiterpenes, and one diterpene. The cultivar ‘She Yang Hong Xin Ju’ exhibited the highest concentration of total terpenoids at approximately 730 µg·g−1 fresh weight. Most cultivars contained sesquiterpenes as the predominant terpenoids. Of them, (E)-β-farnesene was detected in all cultivars. Based on their terpenoid composition, the 12 cultivars were planed into four groups. To gain insights into the function of root secondary metabolites, we performed bioassays to assess their effects on growth of three species of pathogenic fungi: Fusarium oxysporum, Magnaporthe oryzae, and Verticillium dahliae. Significant variability in antifungal activity of the root extracts among different cultivars were observed. The cultivar ‘Xiao Huang Ju’ was the only cultivar that had significant inhibitory effects on all three species of fungi. Our study reveals the diversity of terpenoids in roots of C. morifolium and their function as a chemical defense against fungi.

Chrysanthemum morifolium Ramat is an ornamental plant of worldwide cultivation. Like many other species in the family Asteraceae, C. morifolium is a rich producer of secondary metabolites. There are two objectives in this study: (I) to determine and compare the diversity of apolar secondary metabolites among different cultivars of C. morifolium and (II) to compare their properties as antifungal agents. To attain these objectives, we selected 13 cultivars of C. morifolium that are commonly used for making chrysanthemum tea as experimental materials. Leaves at the same developmental stage were collected from respective mature plants and subjected to organic extraction. The extracts were analyzed using gas chromatography−mass spectrometry. A total of 37 apolar secondary metabolites including 26 terpenoids were detected from the 13 cultivars. These 13 cultivars can be largely divided into three chemotypes based on chemical principal components analysis. Next, the extracts from the 13 cultivars were examined in in vitro assays for their antifungal properties against three species of pathogenic fungi: Fusarium oxysporum, Magnaporthe oryzae, and Verticillium dahliae. Significant variability in antifungal activity of the leaf extracts among different cultivars was observed. The 13 cultivars can be divided into four groups based on their antifungal activities, which could be partly correlated to the contents of terpenoids. In short, this study reveals large variations in chemical composition, particularly of terpenoids, of leaf secondary metabolites among different cultivars of C. morifolium and their different abilities in functioning as antifungal agents.

Ricefield flatsedge (Cyperus iria L.), a troublesome weed in rice production, actively adapts to ecological niches. In this study, terpenoids were identified as the dominant compounds from organic extracts of C. iria leaves. To understand the role of terpenoid production in plant development and resistance to abiotic and biotic stresses, the dynamics of terpenoid production at different developmental stages, and the regulation of these compounds by stresses were determined. Terpenoid production exhibited temporal and spatial specificity. During vegetative growth, the total concentration of sesquiterpenoids increased and reached a maximum at 70 d after germination, and then decreased until the emergence of inflorescence. Monoterpenoids were only detected from leaves 90 d after germination. During reproductive growth, the total concentration of sesquiterpenoids increased dramatically and mainly accumulated in inflorescences, indicating that the sesquiterpenoids were primarily produced in newly formed and actively growing tissues. The total amount of monoterpenoids, mostly accumulated in flowers, increased until 130 d after germination. Furthermore, accumulation of sesquiterpenoids in leaves was promoted significantly by methyl jasmonate (MeJA) and drought treatment. Infestation by beet armyworm (Spodoptera exigua, BAW) promoted the emission of total sesquiterpenoids significantly and induced the production of more monoterpenoids and sesquiterpenoids specifically. Furthermore, volatiles from C. iria leaves had an anti-fungal effect on Fusarium graminearum. The implications of our findings on the biosynthetic pathways leading to the production of sesquiterpenoids in C. iria as well as their potential as fungicides are discussed.

Wilderness search and rescue entails performing a wide-range of work in complex environments and large regions. Given the concerns inherent in large regions due to limited rescue distribution, unmanned aerial vehicle (UAV)-based frameworks are a promising platform for providing aerial imaging. In recent years, technological advances in areas such as micro-technology, sensors and navigation have influenced the various applications of UAVs. In this study, an all-in-one camera-based target detection and positioning system is developed and integrated into a fully autonomous fixed-wing UAV. The system presented in this paper is capable of on-board, real-time target identification, post-target identification and location and aerial image collection for further mapping applications. Its performance is examined using several simulated search and rescue missions, and the test results demonstrate its reliability and efficiency.

In the development of beyond-line-of-sight (BLOS) Unmanned Aerial Vehicle (UAV) systems, communication between the UAVs and the ground control station (GCS) is of critical importance. The commonly used economical wireless modules are restricted by the short communication range and are easily blocked by obstacles. The use of a communication relay system provides a practical way to solve these problems, improving the performance of UAV communication in BLOS and cross-obstacle operations. In this study, a communication relay system, in which a quadrotor was used to relay radio communication for another quadrotor was developed and tested. First, the UAVs used as the airborne platform were constructed, and the hardware for the communication relay system was selected and built up. Second, a set of software programs and protocol for autonomous mission control, communication relay control, and ground control were developed. Finally, the system was fully integrated into the airborne platform and tested both indoor and in-flight. The Received Signal Strength Indication (RSSI) and noise value in two typical application scenarios were recorded. The test results demonstrated the ability of this system to extend the communication range and build communication over obstacles. This system also shows the feasibility to coordinate multiple UAVs’ communication with the same relay structure.