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Abstract Assembly ubiquitously occurs in nature and gives birth to numerous functional biomaterials and sophisticated organisms. In this work, chiral hydrogen-bonded organic-inorganic frameworks (HOIFs) are synthesized via biomimicking the self-assembly process from amino acids to proteins. Enjoying the homohelical configurations analogous to α-helix, the HOIFs exhibit remarkable chiroptical activity including the chiral fluorescence (g lum = 1.7 × 10−3) that is untouched among the previously reported hydrogen-bonded frameworks. Benefitting from the dynamic feature of hydrogen bonding, HOIFs enable enantio-discrimination of chiral aliphatic substrates with imperceivable steric discrepancy based on fluorescent change. Moreover, the disassembled HOIFs after recognition applications are capable of being facilely regenerated and self-purified via aprotic solvent-induced reassembly, leading to at least three consecutive cycles without losing the enantioselectivity. The underlying mechanism of chirality bias is decoded by the experimental isothermal titration calorimetry together with theoretic simulation.

BackgroundMicrobial colonization represents one of the main threats to the conservation of subterranean cultural heritage sites. Recently, the microbial colonization on murals in tombs has gradually attracted attention.MethodsIn this study, a total of 33 samples, including 27 aerosol samples and 6 mural painting samples, were collected from different sites of Xu Xianxiu’s Tomb and analyzed using culture-dependent methods. We compared the diversities of culturable bacteria and fungi isolated from the air and murals and explored the potential impacts of microorganisms on the biodeterioration of the murals.ResultsPhylogenetic analyses revealed that the culturable bacteria belonged to Bacillus, Microbacterium, Lysobacter and Arthrobacter. And the most of fungal belonged to the Penicillium, Cladosporium and Aspergillus genera. The composition and structure of airborne bacteria and fungi outside the tomb were both significantly different from that inside the tomb. The variation trends of airborne bacterial and fungal concentrations at different sampling sites were remarkably similar. Bacillus frigoritolerans, Bacillus halotolerans, Bacillus safensis, Exiguobacterium mexicanum, Microbacterium trichothecenolyticum, and Micrococcus yunnanensis were bacterial species commonly isolated from both the mural and air environments. Fungal species commonly isolated from aerosol samples and mural painting samples were Alternaria alternata, Cladosporium cladosporioides, Penicillium brevicompactum, and Peyronellaea glomerata. The prediction of the ecological functions of the bacteria revealed that chemoheterotrophy or aerobic_chemoheterotrophy accounted for substantial relative proportions in all sample types.ConclusionThese results suggest that the aerosol circulation between the inside and outside environments of the tomb was weak and that the outside environment had yet to have an impact on the air microbial community inside the tomb. Selective colonization of microorganisms, which is mediated by interaction between microorganisms and special microenvironmental factors, is an important reason for the biodeterioration of murals.

Radar signal has been shown as a promising source for human identification. In daily home sleep-monitoring scenarios, large-scale motion features may not always be practical, and the heart motion or respiration data may not be as ideal as they are in a controlled laboratory setting. Human identification from radar sequences is still a challenging task. Furthermore, there is a need to address the open-set recognition problem for radar sequences, which has not been sufficiently studied. In this paper, we propose a deep learning-based approach for human identification using radar sequences captured during sleep in a daily home-monitoring setup. To enhance robustness, we preprocess the sequences to mitigate environmental interference before employing a deep convolution neural network for human identification. We introduce a Principal Component Space feature representation to detect unknown sequences. Our method is rigorously evaluated using both a public data set and a set of experimentally acquired radar sequences. We report a labeling accuracy of 98.2% and 96.8% on average for the two data sets, respectively, which outperforms the state-of-the-art techniques. Our method excels at accurately distinguishing unknown sequences from labeled ones, with nearly 100% detection of unknown samples and minimal misclassification of labeled samples as unknown.

Abstract The conversion of ubiquitous hygrothermal resources into renewable energy offers significant potential for cable‐free, self‐powered systems that can operate worldwide without regard to climatic or geographic limitations. Here, an all‐printed flexible hygro‐thermoelectric paper generator is demonstrated that uses bifunctional mobile ions and electrons to make the moist‐diffusion effect, the Soret effect, and the Seebeck effect work synergistically. In the ordinary hygrothermal settings, it generates an unconventional hygro‐thermoelectric output pattern and shows almost a dozen‐fold increase in positive hygro‐thermopower of 26.70 mV K−1 and also another negative hygro‐thermopower of −15.71 mV K−1 compared to pure thermopower. A single paper generator can produce a giant 680 mV displaying typical cyclic sinusoidal waveform characters with volt‐sized amplitudes. The ion‐electron conductive ink is easily printable and consists primarily of a Bi2Te3/PEDOT:PSS thermoelectric matrix modulated with a hygroscopic glycerol that releases ion charges for moist‐diffusion effect and Soret effect, as well as electron charges for Seebeck effect. The emerged hygro‐thermoelectric harvesting strategy from surrounding hygrothermal resources offers a revolutionary approach to the next generation of hybrid energy with cost‐efficiency, flexibility, and sustainability, and also enables large‐scale roll‐to‐roll production.

Synthesizing vivid images with descriptive texts is gradually emerging as a frontier cross-domain generation task. However, it is obviously inadequate to generate the high-quality image with one single sentence accurately due to the information asymmetry between modalities, which needs external knowledge to balance the process. Moreover, the limited description of the entities in the sentence cannot guarantee the semantic consistency between text and generated image, causing the deficiency of details in foreground and background. Here, we propose a commonsense-driven generative adversarial network to generate photo-realistic images depending on entity-related commonsense knowledge. Commonsense-driven generative adversarial network contains 2 key commonsense-based modules: (a) Entity semantic augment is designed to enhance entity semantics with common sense for abating the information asymmetry, and (b) adaptive entity refinement is used to generate the high-resolution image guided by various commonsense knowledges in multistage for keeping text-image consistency. We demonstrated extensive synthetic cases on the widely used CUB-birds (Caltech-UCSD Birds-200-2011) dataset, where our model achieves competitive results compared to the other state-of-the-art models.

The planting of Cyperus esculentus, a member of the grass family Cyperaceae which includes nut sedge weeds, is being increasingly promoted in northern China’s semi-arid and arid regions. Yet the effects of planting C. esculentus upon soil quality and soil microbial characteristics of sandy land remain unclear. This study examined the short-term (1 year) impact of this grass species on soil microbial biomass indices, enzymatic activities, and microbiome characteristics in the Horqin Sandy Land area of China. The results show that planting C. esculentus could increase microbial biomass in the form of carbon (MBC), nitrogen (MBN), and phosphorus (MBP), but it negligibly influenced the enzymatic activities of soil β-1,4-glucosidase (BG), cellobiohydrolase (CBH), leucine aminopeptidase (LAP), and β-1,4-N-acetaminoglycosidase (NAG). Over 1 year, we found that planting C. esculentus significantly increased the soil bacterial richness and diversity of sandy land, yet also altered community composition of soil bacteria and eukaryotes in way that could promote their homogenization. In this respect, the relative abundances of Acidobacteria and Proteobacteria significantly decreased and increased, respectively; hence, they may be considered for use as important indicators of soil nutrient-rich conditions. Overall, the results could be explained by greater soil organic carbon (SOC) and total nitrogen (TN), mainly derived from cumulative plant litter input to soils, which then increased the sandy soil’s C:N ratio. Future research should focus on exploring the long-term effects of planting C. esculentus on soil quality and soil microbial characteristics of sandy lands in China and abroad.

Soil microorganisms play an important role in the energy flow and nutrient cycling between soil and plants, but the impact of fertilizers on soil bacterial and fungal communities in sandy agroecosystems remains uncertain. We hypothesized that fertilizers affect soil microbial communities through soil properties and plant leaf C:N:P stoichiometry. To test this hypothesis in a sandy farmland ecosystem on the Mongolian Plateau, soil microbial diversity and composition, soil properties and plant leaf C:N:P stoichiometry were examined following 4 years of one of six fertilizer treatments (no fertilizer; returning straw; chemical fertilizer; manure; half quantity of chemical fertilizer and manure; and half quantity of chemical fertilizer). The soil bacterial Shannon index was lowest with chemical fertilizer and half quantity of chemical fertilizer, while fungal Chao richness and phylogenetic diversity (PD) index were lowest with chemical fertilizer. However, chemical fertilizer combined with manure increased the soil bacterial Shannon and PD indices, while manure alone improved fungal Chao richness and the PD index. Fertilizers had a greater impact on the soil bacterial community than on the fungal community and the fungal community was more stable than the bacterial community. Based on redundancy analysis (RDA), total soil carbon, soil nitrogen, leaf carbon, leaf N:P, pH and 16S rRNA gene copy numbers affected the soil microbial community. Structural equation models (SEM) demonstrated that soil pH was a strong driving indicator of soil microbial community under fertilization in a sandy farmland ecosystem. Chemical fertilizer combined with manure out-performed other fertilizers in structuring soil bacterial communities, while chemical fertilizer alone was the worst in maintaining soil microbial communities. Results from this study provide a basis for fertilization management strategies in maintaining below-ground microbial diversity and in ensuring sustainable land development of sandy agroecosystems.

Abstract In order to avoid serious safety accidents caused by closed fire zone, based on the continuous monitoring of atmospheric pressure at different monitoring points in multiple mines, the atmospheric pressure fluctuation model and the air leakage model were established and analyzed. The change law with time of oxygen concentration and gas concentration in the fire zone were obtained due to atmospheric disturbances under the influence of different pressure difference, volume and size of fire area, wind resistance, gas emission, sealing moments, etc. so as to evaluate the explosion risk of a closed fire zone. Research showed that the mine atmosphere fluctuates with the atmosphere of ground, and the pressure difference between the inner and outer sides of the enclosed fire zone is affected by the periodic fluctuation of atmosphere, which has about 16-h cosine fluctuation and approximate 8-h fixed value. Compared with the fire zone with poor sealing quality, good sealing fire zone has better resistance to atmospheric disturbance. The reduction of oxygen concentration in the inner side of a well-sealed fire zone mainly depends on the dilution of methane, which is more likely to accumulate and rise rapidly. And the fire zone with poor sealing quality is easy to be interfered. The inner oxygen concentration and gas concentration are easily affected by the absolute gas emission and the air leakage in the fire zone. Fire zone with small wind resistance and small volume is especially obvious. At the initial stage of the closed fire zone it's very possible to happen explosion. The time duration of explosion danger varies under different conditions, and the atmospheric disturbance may lead to repeated explosions in some cases. It's suggested to take some methods to avoid explosions according to the real-time situation, closure time, oxygen concentration and gas concentration of fire zone.

Stock estimates are critical to quantifying carbon and nitrogen sequestration, quantifying greenhouse gas emissions, and understanding key biogeochemical processes (i.e., soil carbon and nutrient cycling). Many studies have assessed soil organic matter and nutrients in different ecosystems. However, the spatial distribution of carbon and nitrogen and the key influencing factors in arid desert steppe remain unclear. Here, we investigated the soil organic carbon (SOC) and soil total nitrogen (STN) to a depth of 100 cm at 126 sites in a desert steppe in northwestern China. SOC and STN contents decreased with increasing depth; the highest average SOC and STN contents were 12.70 and 0.65 g kg−1 in the surface 5 cm, and the lowest were from 80 to 100 cm (4.49 and 0.16 g kg−1, respectively). SOC density (SOCD) and STN density (STND) to a depth of 100 cm averaged 8.94 and 0.45 kg m−2, respectively. The top 1 m of the soils stored approximately 1,041 Tg SOC and 52 Tg STN in the study area. Geostatistical analysis showed strong and moderate spatial autocorrelation for SOCD in different soil layers, but the autocorrelation for STND gradually weakened with increasing depth. SOCD and STND decreased from southwest to northeast in the study area, along an elevation gradient. Both were significantly positively correlated with topographic variables, precipitation, and the normalized-difference vegetation index, but negatively correlated with temperature and aridity. More than 40% of the SOCD and STND spatial variation was explained by elevation, which was the dominant factor. The data and high-resolution maps from this study will support future soil carbon and nitrogen analyses.

Biological soil crusts (BSCs) are an integration of external photoautotrophs and internal heterotrophic communities. Sand burial is a ubiquitous disturbance that affects the biodiversity and ecological function of BSCs, but little is known about the influence of sand burial on microbial communities in arid sandy deserts. Here, based on a long-term field experiment and utilizing high-throughput sequencing, we assessed the influence of sand burial on bacterial and fungal communities inhabiting two typical successional stages of BSCs (cyanobacterial crusts for early successional stage and mixed crusts for late successional stage) at the three-sand buried depth (0, 0.5, and 10 mm) in the Tengger Desert, Northern China. We found that the diversity, abundance, and composition of the bacterial and fungal communities were all altered by the sand burial treatment. Different indicator taxa were identified in unburied and buried (shallow and deep) BSCs. Changes in soil properties caused by sand burial have been suggested as a possible cause of changes in the bacterial and fungal community composition in BSCs.

Bacterial, archaeal, and eukaryota diversity in mountainous areas varies along elevational gradients, but details remain unclear. Here, we use a next-generation sequencing method based on 16S/18S rRNA to reveal the soil microbial diversity and community compositions of alpine meadow ecosystems along an elevation span of nearly 2,000 m (1,936–3,896 m) in China’s Qilian Mountains. Both bacterial and eukaryota diversity increased linearly with increasing elevation, whereas archaeal diversity increased, but not significantly. The diversity patterns of several phyla in the bacterial, archaeal, and eukaryota communities were consistent with the overall elevational trend, but some phyla did not follow this pattern. The soil microbial community compositions were shaped by the coupled effects of regional climate and local soil properties. Intradomain links were more important than interdomain links in the microbial network of the alpine meadows, and these links were mostly positive. The bacteria formed more connections than either archaea or eukaryota, but archaea may be more important than bacteria in building the soil microbial co-occurrence network in this region. Our results provide new visions on the formation and maintenance of soil microbial diversity along an elevational gradient and have implications for microbial responses to climate change in alpine ecosystems.

Molecular crystals that show a reversible shape change by external stimuli are invaluable for the design of actuators but their strong deformations usually lead to their destruction. Here the authors report a fluorenone derivative showing a strong, reversible and instantaneous shear deformation upon heating due to a structural phase transition.

Caragana microphylla is a sand-fixing leguminous shrub with strong resistance to drought, cold, and low soil fertility. As a result, it plays an essential role in combating desertification in northern China, but little is known about its nutrient budget. Nutrient resorption is a key process in plant nutrient conservation and has marked ecological implications for plant fitness and ecosystem nutrient cycling. We studied the effects of both nitrogen (N) addition and reproductive effort on leaf N resorption of C. microphylla in a temperate semi-arid sandy land in China. The results showed that sprouting of the early leaves from over-wintered buds employs a strategy for slow returns on nutrient investment with smaller specific leaf area (SLA) and higher N resorption efficiency, whereas the late leaves, which sprout from current-year buds, employ a strategy for quick returns on nutrient investment with higher SLA and lower N resorption efficiency. N addition significantly increased the N resorption efficiency from early leaves while exerting no impact on late leaves, suggesting that the increased N recovery from early leaves is done to sustain the high N demands of late leaves. Reproductive effort did not affect the N resorption from early or late leaves due to the temporal separation between fruit production and leaf senescence. Taken together, our results demonstrate that C. microphylla has evolved different investment strategies for leaf N in early and late leaves to conserve nutrients and facilitate its growth in desertified environments.

[This corrects the article DOI: 10.1371/journal.pone.0179718.].

In this study, a culture-independent Illumina MiSeq sequencing strategy was applied to investigate the microbial communities colonizing the ancient painted sculptures of the Maijishan Grottoes, a famous World Cultural Heritage site listed by UNESCO in China. Four mixed samples were collected from Cave 4-4 of the Maijishan Grottoes, the so-called Upper Seven Buddha Pavilion, which was built during the Northern Zhou Dynasty (557-581AD). The 16/18S rRNA gene-based sequences revealed a rich bacterial diversity and a relatively low fungal abundance, including the bacterial groups Actinobacteria, Acidobacteria, Bacteroidetes, Cyanobacteria, Chloroflexi, Firmicutes, Proteobacteria and Verrucomicrobia and the fungal groups Ascomycota, Basidiomycota and Chytridiomycota. Among them, the bacteria genera of Pseudonocardia and Rubrobacter and unclassified fungi in the order of Capnodiales were dominant. The relative abundance of Pseudonocardia in the painted layer samples was higher than that in the dust sample, while Cyanobacteria dominated in the dust sample. Many of them have been discovered at other cultural heritage sites and associated with the biodeterioration of cultural relics. The presence and activity of these pioneering microorganisms may lead to an unexpected deterioration of the painted sculptures that are preserved in this heritage site. Thus, proper management strategies and potential risk monitoring should be used in the Maijishan Grottoes to improve the conservation of these precious painted sculptures.

A wireless sensor network (WSN) is composed of a large collection of sensor nodes with limited resources in terms of battery supplied energy, processing capability, and storage. Therefore, the design of an energy-efficient and scalable routing protocol is a crucial concern for WSN applications. In this paper, we propose Bee-Sensor-C, an energy-aware and scalable multipath routing protocol based on dynamic cluster and foraging behavior of a bee swarm. Bee-Sensor-C is an evolution from BeeSensor which is a bee-inspired routing protocol for WSNs. First of all, through introducing a dynamic clustering scheme, Bee-Sensor-C offers parallel data transmissions close to the event area. This evolution reduces routing overhead and improves the scalability. Moreover, Bee-Sensor-C adopts an enhanced multipath construction method in order to achieve the balance of the network energy consumption. Besides, Bee-Sensor-C can well support the multicluster scenario. Through simulations, the network performance is evaluated and the results demonstrate that Bee-Sensor-C outperforms the existing protocols in terms of energy efficiency, energy consumption balance, packet delivery rate, and scalability.

Visual Question Answering (VQA) is a task that involves predicting an answer to a question depending on the content of an image. However, recent VQA methods have relied more on language priors between the question and answer rather than the image content. To address this issue, many debiasing methods have been proposed to reduce language bias in model reasoning. However, the bias can be divided into two categories: good bias and bad bias. Good bias can benefit to the answer prediction, while the bad bias may associate the models with the unrelated information. Therefore, instead of excluding good and bad bias indiscriminately in existing debiasing methods, we proposed a bias discrimination module to distinguish them. Additionally, bad bias may reduce the model's reliance on image content during answer reasoning and thus attend little on image features updating. To tackle this, we leverage Markov theory to construct a Markov field with image regions and question words as nodes. This helps with feature updating for both image regions and question words, thereby facilitating more accurate and comprehensive reasoning about both the image content and question. To verify the effectiveness of our network, we evaluate our network on VQA v2 and VQA cp v2 datasets and conduct extensive quantity and quality studies to verify the effectiveness of our proposed network. Experimental resu- lts show that our network achieves significant performance against the previous state-of-the-art methods. [ABSTRACT FROM AUTHOR]

The factor of combustion and explosion remains one of the main constraints on coal mining and management. To clarify the impact of structural properties on the consequences of gas explosion disasters during coal mining, this article conducts a study on the impact of the elastic modulus of structures on gas explosion disasters. The research results indicate that in the case where structures with high elastic modulus must exist, the elastic modulus of the structure has minimal impact on the structure during the early stage of flame development. The area of flame front and the degree of deflagration also decrease with the increase of elastic modulus, but the disturbance degree of air-flow and flame in the pipe increases with the increase of elastic modulus. The peak flame velocity at elastic modulus of 0.7 GPa and 2.8 GPa increased by 3.56% and 7.47% compared to elastic modulus of 0.18 GPa, respectively. The upstream overpressure peak increased by 24.63% and 42.52%. The downstream overpressure peak increased by 11.19% and 20.62%. The peak values of flame velocity and overpressure increase with the increase of elastic modulus, while the explosion intensity and pressure rise rate increase with the increase of elastic modulus. The explosion intensity index at elastic modulus 2.8 GPa is approximately 1.45 times that at elastic modulus 0.18 GPa. Therefore, it is necessary to choose structures with smaller elastic modulus as much as possible to achieve the best fire and explosion suppression effect. [ABSTRACT FROM AUTHOR]

To improve the explosion suppression efficiency of porous media in natural gas hydrogen-doped pipelines, this paper designs and builds an experimental platform with dimensions of 10 cm × 10 cm × 100 cm organ transparent glass explosion pipeline and researches the synergistic effect of the use of nickel foam and CO2 to inhibit the explosion of hydrogen-doped methane with a hydrogen doping ratio of φ = 10%. Studies have shown that using a dual explosion suppression mechanism, the synergistic effect of nickel foam and CO2 acting at different jet positions has a significant inhibitory effect on the flame and overpressure of low-hydrogen-ratio methane explosions. The synergistic CO2 in porous media has a more potent inhibitory effect on the right-side wall jet than on the left-side and left-side jet. When the synergistic impact of nickel foam and CO2 acts on the right-side wall jet, the flame is quenched, substantially attenuating the overpressure peak. When the nickel foam synergistic CO2 acts on the right-side wall jet, the optimal effect is achieved when the CO2 jet pressure is set at 0.3 MPa, which successfully quenches the flame and significantly reduces the overpressure peak. However, the dual explosion suppression mechanism fails when the CO2 jet pressure is 0.2 MPa. [ABSTRACT FROM AUTHOR]

Based on the self-built experimental set-up, the propagation law of explosion flame of hydrogen/methane premixed gas with different hydrogen volume fractions in different equivalent ratios was investigated under the action of a corrugated fire-retardant core. The experimental study shows that the flame isolation and suppression effect of the corrugated fire-retardant core at different equivalence ratios is either promoted or suppressed, the hydrogen/methane premixed gas explosion flame is quenched without hydrogen mixing when ϕ = 0.8 and 1.0, and also quenched when ϕ = 1.2 in different hydrogen volume fractions. The corrugated flame-retardant core significantly affected the extinguishing of the explosion flame of the premixed gas when ϕ = 1.2, the flame propagation speed and overpressure showed a similar trend under different volume fractions of hydrogen. When the flame is quenched, the flame is depressed inward to form a reverse spherical cell flame, reverse diffusion combustion phenomenon occurs, and it lasts a long time, eventually, the combustion reaction extinguished. The flame penetrated the corrugated fire-retardant core during the rest of conditions. When ϕ = 1.0, the flame reaction of the hydrogen/methane premixed gas explosion under the action of the corrugated fire-retardant core is the most violent, and its propagation speed and overpressure jump rapidly until it reaches a peak. [ABSTRACT FROM AUTHOR]