Waveguide-integrated twisted bilayer graphene photodetectors.

Graphene photodetectors have exhibited high bandwidth and capability of being integrated with silicon photonics (SiPh), holding promise for future optical communication devices. However, they usually suffer from a low photoresponsivity due to weak optical absorption. In this work, we have implemented SiPh-integrated twisted bilayer graphene (tBLG) detectors and reported a responsivity of 0.65 A W-1 for telecom wavelength 1,550 nm. The high responsivity enables a 3-dB bandwidth of >65 GHz and a high data stream rate of 50 Gbit s-1. Such high responsivity is attributed to the enhanced optical absorption, which is facilitated by van Hove singularities in the band structure of high-mobility tBLG with 4.1o twist angle. The uniform performance of the fabricated photodetector arrays demonstrates a fascinating prospect of large-area tBLG as a material candidate for heterogeneous integration with SiPh.

Enhancing the Gelation Behavior of Transglutaminase-Induced Soy Protein Isolate(SPI) through Ultrasound-Assisted Extraction.

Gelation, as an important functional property of soy protein isolate (SPI), can be improved by some green technologies in food manufacturing, including ultrasound, ultrahigh pressure and microwave treatments. This work investigated the effect of an alkaline solubilisation step in SPI extraction combined with sonication on protein properties. The TGase-induced gel of the modified SPI was prepared to explore the effect of ultrasound on gel properties, including structures, strength, water-holding capacity and rheological properties. Additionally, the differences between traditional ultrasound modification of SPI and current modification methods were analyzed. The results showed that the ultrasonication-assisted extraction method could result in a significant increase in extraction rate from 24.68% to 42.25%. Moreover, ultrasound-assisted modification of SPI gels induced with transglutaminase (TGase) exhibited significant improvement in mechanical properties, such as texture, water-holding capacity and rheological properties, In particular, SPI extracted at 400 W ultrasound intensity for 180 s showed the best overall performance in terms of gel properties. Our method efficiently uniformizes gel structure, enhancing mechanical properties compared to conventional ultrasound methods, which reduced energy consumption and costs. These findings provide insights into the production of high-gelation SPI in food manufacturing.

High resolution dissolved heavy metals in sediment porewater of a small estuary: Distribution, mobilization and migration.

Identifying the distribution features, mobilization mechanisms and migration processes of heavy metals (HMs) in estuarine sediments is essential to predict their potential toxicity risk and for following contamination remediation. In this study, high-resolution dialysis (HR-Peeper) and a sequential extraction procedure were employed to determine the porewater dissolved iron (Fe), manganese (Mn), arsenic (As), chromium (Cr), vanadium (V), selenium (Se), molybdenum (Mo), nickel (Ni), zinc (Zn) and their geochemical species fractions in sediments of the Xixi River Estuary, Xiamen, China. The results showed that at estuarine sites with high TOC and TS content, sulfate reduction is the main diagenetic pathway of OC degradation and directly inhibits the reduction of Fe/Mn oxides. The mobility of most HMs in porewater profiles was influenced by multiple factors, such as the adsorption-desorption by Fe/Mn oxides, HM-sulfide co-precipitation, and the degradation of OM under different redox conditions. However, no environmental correlation and control factors of Ni and Zn have been found. In addition, the profile-averaged distribution of most HMs showed a seaward increasing trend, probably due to the severe industrial wastewater discharge and increasing salinity responsible for the competitive adsorption of HM ions. The overall positive fluxes of all HMs, together with the higher positive diffusion fluxes of some HMs such as Mn, Cr, V and Zn, suggest that the HMs mobility in small estuarine sediments should be seriously reconsidered due to its high contamination potential.

Regularity of rural settlement changes driven by rapid urbanization in North China over the three decades.

The systematic decline of rural areas in the process of rapid urbanization has become a global trend, creating greater challenges for sustainable rural development. As the spatial projection of socio-economic development and living environment in rural areas, the continuous tracking of rural settlements (RUS) is crucial to quantify the imbalance of rural development. However, consistent information on RUS is highly needed but is quite deficient in current research. In this study, a cost-effective mapping model was proposed to produce an annual RUS dataset in the rapid urbanization region of Beijing-Tianjin-Hebei (BTH) in North China during 1990-2020, and the temporal-spatial regularity of RUS changes was further analyzed. The location-based and the area-based comparison verified the effectiveness of our model, with a mean overall accuracy of 85% and a mean correlation value of 0.88, respectively. The total area of RUS in the BTH region increased by 2561 km2 from 1990 to 2020, while the average size of RUS remained stable after 2005. The annual change trends in RUS appeared with increasing and decreasing accounting for 76.33% and 23.67%, respectively. The centroids of RUS in Tianjin and Hebei have moved closer to Beijing, while those in Beijing have moved away from the former. Notably, we have identified 56.3% counties in the BTH region belong to the "Convex-I" change type in RUS. In general, our work can help to consistently quantify the spatiotemporal patterns of RUS in a cost-effective way, providing more explicit spatial information and continuous temporal information for rural residential land management.

Coastal aquaculture regulates phosphorus cycling in estuarine wetlands: Mobilization, kinetic resupply, and source-sink process.

Estuarine mangrove wetlands have gradually declined owing to the growing construction of aquaculture ponds. How the speciation, transition, and migration of phosphorus (P) adaptively change in the sediments of this pond-wetland ecosystem remains unclear. In this study, we used high-resolution devices to explore the contrasting P behaviors associated with the redox cycles of Fe-Mn-S-As in estuarine and pond sediments. The results showed that the construction of aquaculture ponds increased the content or percentage of the silt, organic carbon, and P fractions in sediments. Dissolved organic P (DOP) concentrations in pore water were fluctuant with depths, accounting for only 18±15% and 20±11% of total dissolved P (TDP) in estuarine and pond sediment, respectively. Furthermore, DOP was less strongly correlated with other P species, including Fe, Mn, and sulfide. The coupling of dissolved reactive P (DRP) and TDP with Fe and sulfide confirmed that P mobility is regulated by Fe redox cycling in estuarine sediments, whereas Fe(III) reduction and sulfate reduction co-regulate P remobilization in pond sediments. The apparent diffusion flux revealed all sediments acting as sources for TDP (0.04-0.1 mg m-2 d-1) to the overlying water, while mangrove sediments were sources of DOP, and pond sediments were major sources of DRP. The DIFS model overestimated the P kinetic resupply ability, which was evaluated using DRP rather than TDP. This study improves our understanding of P cycling and budget in aquaculture pond-mangrove ecosystems and has important implications for understanding water eutrophication more effectively.

Spatiotemporal Pattern of Cultivated Land Pressure and Its Influencing Factors in the Huaihai Economic Zone, China.

Cultivated land pressure represents a direct reflection of grain security. Existing relevant studies rarely approached the spatiotemporal pattern of cultivated land pressure or the spatial heterogeneity of its influencing factors from the level of economic zones. Taking the Huaihai Economic Zone (HEZ), China for case analysis, this study investigated the spatiotemporal pattern of cultivated land pressure in diverse periods from 2000 to 2018 based on a modified cultivated land pressure index and spatial correlation models. On this basis, it explored the influencing factors of the spatial differentiation of cultivated land pressure in the late stage of the study using geographical detector as well as multi-scale geographically weighted regression model. The results indicated that: 1) in the study period, the global cultivated land pressure index of the study area decreased gradually, but cultivated land pressure increased locally in a significant way, especially in the central and southern Shandong Province; 2) the spatial pattern of cultivated land pressure manifested global clustering features. Hot and secondary-hot spots presented a narrowing and clustering trend, whereas cold and secondary-cold spots manifested a spreading and clustering trend; 3) average slope, the proportion of non-grain crops, population urbanization rate, and multiple cropping index have significant effects on the spatial differentiation of cultivated land pressure. The former three factors were positively correlated with cultivated land pressure, and the last factor was negatively correlated with cultivated land pressure; and 4) the amount of cultivated land has increased in the central and southern Shandong Province through land consolidation which, nonetheless, failed to improve the grain production. In regards to major grain producing areas similar to the HEZ in China, the authors suggest that great importance should be given to the balance of the quality and quantity of cultivated land, the optimization of agricultural production factors and the rational control of non-grain crops, thus providing a powerful guarantee for grain security in China.

An outbreak of tuberculosis in endangered northern pig-tailed macaques (Macaca leonina) and milu deer (Elaphurus davidianus) from a zoo in China.

BACKGROUND: Tuberculosis (TB) is a zoonotic disease that affects humans and domesticated and wild animals. Animals in zoos are potentially an important source of TB for humans; however they are often neglected in routine disease surveillance programs. This investigation reports an outbreak of TB in milu deer and northern pig-tailed macaques in a zoo in Wuhan, China, which highlighted the need for improved prevention and control of TB in China. METHODS: Between 24 November and 9 December 2020 two milu deer and a northern pig-tailed macaque that were displaying signs of wasting died. Post-mortem, histopathological diagnosis and acid fast staining were used for the dead animals. Multiple PCR for Mycobacterium tuberculosis complex (MTBC) was performed to identify the bacterial in both milu deer and northern pig-tailed macaque. The serum antibody iELISA for MTBC was then performed for all the surviving milu deer and northern pig-tailed macaques. Six seropositive milu deer and a seropositive northern pig-tailed macaque were subsequently euthanised and, along with two other dead milu deer, necropsied. DNA from these tissue samples was extracted and detected MTBC using PCR and Real-time PCR. Subsequently bacterial isolation was used to confirm the infection. RESULTS: The lungs of the dead animals displayed gross and histological TB-like lesions and changes, and red staining bacilli were detected in smears of the lesions by microscopy after acid fast staining. Mycobacterium bovis (M. bovis) was detected in the two milu deer and Mycobacterium tuberculosis (M. tb) in the northern pig-tailed macaque using multiple PCR for MTBC. 35.3% surviving milu deer and 50% surviving northern pig-tailed macaques MTBC serologically positive. Six of the euthanised milu deer were also positive on a DNA test for M. bovis and the euthanised northern pig-tailed macaque was positive to M. tb. CONCLUSIONS: This is the first report of tuberculosis in the endangered species, milu deer and northern pig-tailed macaques, in China, and warrants urgent attention by researchers and conservation authorities. These cases highlight the need for expanding surveillance for MTBC to zoos in China.

Attention-Based Sequence-to-Sequence Model for Time Series Imputation.

Time series data are usually characterized by having missing values, high dimensionality, and large data volume. To solve the problem of high-dimensional time series with missing values, this paper proposes an attention-based sequence-to-sequence model to imputation missing values in time series (ASSM), which is a sequence-to-sequence model based on the combination of feature learning and data computation. The model consists of two parts, encoder and decoder. The encoder part is a BIGRU recurrent neural network and incorporates a self-attentive mechanism to make the model more capable of handling long-range time series; The decoder part is a GRU recurrent neural network and incorporates a cross-attentive mechanism into associate with the encoder part. The relationship weights between the generated sequences in the decoder part and the known sequences in the encoder part are calculated to achieve the purpose of focusing on the sequences with a high degree of correlation. In this paper, we conduct comparison experiments with four evaluation metrics and six models on four real datasets. The experimental results show that the model proposed in this paper outperforms the six comparative missing value interpolation algorithms.

Magnetic graphene oxide-based covalent organic frameworks as novel adsorbent for extraction and separation of triazine herbicides from fruit and vegetable samples.

A novel magnetic graphene oxide-based covalent organic frameworks, was prepared initially by grafting two monomers, tris(4-aminophenyl)amine and 2, 4, 6-triformylphloroglucinol onto Fe3O4 nanoparticles attached to graphene oxide scaffolds. It exhibited a regular core-shell spherical structure, super paramagnetism, and desirable adsorbability for five triazine herbicides, and was thus served as adsorbent of magnetic solid-phase extraction. An analytical strategy coupled magnetic solid phase extraction with UHPLC-MS/MS was then developed for the determination of triazine herbicide residues in fruit and vegetable samples. The validation results revealed good linearity in the concentration range of 0.01-200 µg L-1(r≥0.9925). LODs of the method were in the range of 0.01-0.05 µg kg-1, LOQs in the range of 0.05-0.2 µg kg-1 and recoveries ranged from 72.3 to 112.8%. The results showed that the prepared adsorbent provided desirable adsorption capacity of triazine herbicides, demonstrating great potential in the detection of trace triazine herbicides in complex food matrices.

Facile synthesis of a novel magnetic covalent organic frameworks for extraction and determination of five fungicides in Chinese herbal medicines.

A novel magnetic covalent organic framework was synthesized via a one-step coating approach with solvothermal reaction employing 2,4,6-tris(4-aminophen-yl)-1,3,5-triazine and 2,4,6-triformylphloroglucinol as two building blocks by covalent bonding. The prepared magnetic covalent organic frameworks were properly characterized by different techniques and employed as adsorbents of magnetic solid-phase extraction. An analytical method was developed for the simultaneous determination of five fungicides in two Chinese herbal medicine samples via magnetic solid-phase extraction coupled to ultra high performance liquid chromatography with tandem mass spectrometry analysis. Under optimized magnetic solid-phase extraction conditions, the method exhibited satisfactory recoveries (74.0-109.6%) with relative standard deviations of 0.4-4.6%, low limits of detection (0.003-0.015 µg/kg), and good linearity (R2 > 0.9960). Compared with the traditional extraction method, the proposed method required a lower amount of adsorbent (3 mg) and extraction time (5 min). The adsorbent also had favorable reusability (not less than eight times). Therefore, the magnetic covalent organic frameworks could be a promising adsorbent for the extraction and quantitation of fungicides in Chinese herbal medicines.

Cu-Doped Boron Nitride Nanosheets for Solid-Phase Extraction and Determination of Rhodamine B in Foods Matrix.

Cu-doped boron nitride nanosheets (Cu-BNNS) were first reported as promising adsorbents for the solid-phase extraction and determination of rhodamine B (RhB) dye in a food matrix. Different characterizations, including XRD, FTIR, XPS, SEM, and TEM, were performed to confirm the formation of the adsorbent. Then, the adsorption performance of Cu-BNNS was investigated by adsorption kinetics, isotherms, and thermodynamics. Multiple extraction parameters were optimized by single-factor experiments. Under optimized conditions, the recoveries in the food matrix were in the range of 89.8-95.4%, with the spiked levels of 100 ng/mL and 500 ng/mL, respectively. This novel system was expected to have great potential to detect RhB in a wide variety of real samples.

Tissue distribution study of perfluorooctanoic acid in exposed zebrafish using MALDI mass spectrometry imaging.

Perfluorooctanoic acid (PFOA) as an emerging environmental contaminant, has become ubiquitous in the environment. It is of significance to study bioconcentration and tissue distribution of aquatic organisms for predicting the persistence of PFOA and its adverse effects on the environment and human body. However, the distribution of PFOA in different tissues is a complex physiological process affected by many factors. It is difficult to be accurately described by a simple kinetic model. In present study, a new strategy was introduced to research the PFOA distribution in tissues and estimate the exposure stages. Zebrafish were continuously exposed to 25 mg/L PFOA for 30 days to simulate environmental process. Matrix-assisted laser desorption ionization mass spectrometry imaging (MALDI-MSI) method was used to monitor the spatio-temporal distribution of PFOA in zebrafish tissues. By analyzing the law of change obtained from the high spatial resolution MSI data, two different enrichment trends in ten tissues were summarized by performing curve fitting. Analyzing the ratio of two types of curves, a new "exposure curve" was defined to evaluate the exposure stages. With this model, three levels (mild, moderate, and deep pollution stage) of PFOA pollution in zebrafish can be simply evaluated.

Reconsidering the efficiency of grazing exclusion using fences on the Tibetan Plateau.

Grazing exclusion using fences is a key policy being applied by the Chinese government to rehabilitate degraded grasslands on the Tibetan Plateau (TP) and elsewhere. However, there is a limited understanding of the effects of grazing exclusion on alpine ecosystem functions and services and its impacts on herders' livelihoods. Our meta-analyses and questionnaire-based surveys revealed that grazing exclusion with fences was effective in promoting aboveground vegetation growth for up to four years in degraded alpine meadows and for up to eight years in the alpine steppes of the TP. Longer-term fencing did not bring any ecological and economic benefits. We also found that fencing hindered wildlife movement, increased grazing pressure in unfenced areas, lowered the satisfaction of herders, and rendered substantial financial costs to both regional and national governments. We recommend that traditional free grazing should be encouraged if applicable, short-term fencing (for 4-8 years) should be adopted in severely degraded grasslands, and fencing should be avoided in key wildlife habitat areas, especially the protected large mammal species.

The Haze Nightmare Following the Economic Boom in China: Dilemma and Tradeoffs.

This study aims to expand on a deeper understanding of the relationship between rapid economic development and ensuing air pollution in China. The database includes the gross domestic product (GDP), the value added of a secondary industry, the per capita GDP (PGDP), greenhouse gases emissions, and PM2.5 concentrations. The results indicate that China's PGDP has continued to rise over the past decade, and the rate of PGDP slowed down from 1980 to 2004 (slope = 5672.81, R² = 0.99, p < 0.001) but was significantly lower than that from the year 2004 to 2013 (slope = 46,911.08, R² > 0.99, p < 0.001). Unfortunately, we found that total coal consumption, annual steel production, and SO2 emission had been continually growing as the overall economy expands at temporal scale, with the coefficient of determinations greater than 0.98 (p < 0.001). Considering the spatial pattern aspect, we also found a significant relationship between GDP and greenhouse gases. Meanwhile, severe air pollution has negatively impacted the environment and human health, particularly in some highlighted regions. The variation explained by both total SO2 emission and total smoke and dust emission were 33% (p < 0.001) and 24% (p < 0.01) for the rate of total pertussis at temporal scale, respectively. Furthermore, at the spatial scale, pulmonary tuberculosis rates and pertussis mainly occurred in area with serious air pollution (economically developed region). It can be summarized that the extensive mode of economic growth has brought a number of serious environment and human health problems. Thus, a new policy framework has been proposed to meet the goals of maintaining a healthy economy without harming natural environment, which may prove integral, especially when coupled with long-term national strategic development plans.

[Decomposing effect of chemical-biological decomposing combined technique on rice straw and its fourier transform infrared spectroscopy].

The effects of several chemical-biological combined decomposing techniques (CBCDT) on the decomposition of rice straw were studied by fourier transform infrared spectroscopy (FTIR). The results showed that under CBCDT treatments, rice straw could be better decomposed than in control. After seven days under CBCDT treatments, the straw turned into brown, and was easy to be broken down and obviously decomposed. FTIR spectra indicated that under chemical agent A-biological agent A combined treatment, hydroxyl, ketonic carbonyl, methyl, methylene, methane and aliphatic compounds decreased, proteins and amino acids completely decomposed, but aromatic compounds (specially substituted group) increased, and hence, the humification of straw was accelerated. The effects of different decomposing agents on straw were decreased in the order of chemical degrade agent A > chemical degrade agent B, biological degrade agent A > biological degrade agent B > biological degrade agent C. The chemical agent A-biological agent A combined treatment was the most effective among several treatments.