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Regime shifts between nitrogen (N) and phosphorus (P) limitation, which trigger cyanobacterial succession, occur in shallow eutrophic lakes seasonally. However, the underlying mechanism is not yet fully illustrated. We provide a novel insight to address this from interactions between sediment P and nitrification through monthly field investigations including 204 samples and microcosm experiments in Lake Chaohu. Total N to P mass ratios (TN/TP) varied significantly across seasons especially during algal bloom in summer, with the average value being 26.1 in June and descending to 7.8 in September gradually, triggering dominant cyanobacterial succession from Microcystisto Dolichospermum. The regulation effect of sediment N/P on water column TN/TP was stronger in summer than in other seasons. Iron-bound P and alkaline phosphatase activity in sediment, rather than ammonium, contributed to the higher part of nitrification. Furthermore, our microcosm experiments confirmed that soluble active P and enzymatic hydrolysis of organic P, accumulating during algal bloom, fueled nitrifiers and nitrification in sediments. These processes promoted lake N removal and led to relative N deficiency in turn. Our results highlight that N and P cycles do not exist independently but rather interact with each other during lake eutrophication, supporting the dual N and P reduction program to mitigate eutrophication in shallow eutrophic lakes.

To explore the effect of different types of dissolved organic matter (DOM) decomposition on nutrient cycling pathways and the microbial loop, four lakes with different DOM sources were investigated monthly. In Lake Tangxun, Dolichospermumdecay released highly labile dissolved organic nitrogen into the water column. This induced bacterial organic nitrogen decomposition, as indicated by the increased abundance of gltB, gltD, gdh, and glnAas well as aminopeptidase activity. Genes associated with dissimilatory nitrate reduction to ammonium further fueled ammonium accumulation, driving Microcystisblooms in the summer. In Lake Zhiyin, fish bait deposits (high nitrogen, similar to Dolichospermumdetritus) also caused Microcystisblooms. Detritus from Microcystisdecomposition then produced high levels of labile dissolved organic phosphorus, inducing phosphatase activity and increasing soluble reactive phosphorus concentrations from September to April in Lakes Tangxun and Zhiyin. The high refractory DOM from macrophytes in Lake Houguan led to insufficient nutrient availability, leading to nutrient mutualism between algae and bacteria. The high levels of labile dissolved organic carbon from terrestrial detritus in Lake Yandong increased bacterial biomass and production, resulting in low chlorophyll content due to the competitive relationship between algal and bacterial nutrient requirements. Therefore, different DOM compositions induce unique connections among available nutrients, algae, and bacteria in the microbial loop.

African swine fever is an acute, severe and highly contagious infectious disease caused by African swine fever virus (ASFV), posing a huge threat to the global swine industry. Rapid and accurate diagnostic methods are of great significance for the effective prevention and control of ASFV transmission. In this work, we established and evaluated a graphene oxide-based accelerated strand exchange amplification (GO-ASEA) method for rapid, highly sensitive, and quantitative detection of ASFV. The use of GO provided a novel solution reference for improving the specificity of strand exchange amplification and solving the potential false positive problem caused by primer dimers. The detection limit of the GO-ASEA assay was 5.8 × 10−1copies per μL of ASFV (equal to 2.9 copies per reaction) or 5.8 × 100copies per μL of ASFV in spiked swine nasal swabs. The selectivity of the GO-ASEA assay was supported by the ASFV DNA reference material and another seven porcine-derived viruses with similar clinical symptoms. The GO-ASEA assay took only about 29 minutes and was validated with 6 inactivated specimens and 52 swine nasal swabs, showing excellent clinical applicability. The novel assay is an accurate and practical method for rapid, highly sensitive detection of ASFV, and can potentially serve as a robust tool in epidemic prevention and point-of-care diagnosis.

In recent years, in order to protect the security of medical privacy data, a large number of telemedicine authentication protocols have been proposed. Some protocols use digital signature methods to achieve two-way authentication among patients, doctors and medical servers, so the execution efficiency of protocol is low. Some protocols fail to achieve patient identity anonymity, the true identity of patient can be analysed by the doctor, so it can't resist security attacks. In order to solve the above problems, a more secure telemedicine authentication protocol is proposed in this paper, which implements two-way identity authentication in the telemedicine authentication model using SHA-1 hash function, time stamp and random number operations. In addition, the introduction of temporary identity can achieve patient identity anonymity and personal medical data security. The protocol has better performance in terms of security, storage and computing overhead, it is more suitable for telemedicine authentication system.

Dolichospermum flos-aquae(formerly Anabaena flos-aquae) is a diazotrophic cyanobacterium causing harmful blooms worldwide, which is partly attributed to its capacity to compete for nitrogen (N) and phosphorus (P). Preventing the blooms by reducing P alone or both N and P has caused debate. To test the effects alone and together on the growth of cyanobacteria, we performed culture experiments in different eutrophication scenarios. N2fixation in terms of heterocyst density, nitrogenase activity and nifHexpression increased significantly in P-replete cultures, suggesting that P enrichment facilitates N2fixation. Correspondingly, the expression of genes involved in P uptake, e.g., those involved in P-transport (pstS) and the hydrolysis of phosphomonoesters (phoD), was upregulated in P-deficient cultures. Interestingly, N addition enhanced not only the expression of these genes but also polyphosphate formation and alkaline phosphatase activity in P-deficient cultures relative to the P-replete cultures, as evidenced by qualitative (enzyme-labeled fluorescence) and quantitative (fluorogenic spectrophotometry) measurements. Furthermore, after N addition, cell activity and growth increased in the P-deficient cultures, underscoring the risk of N enrichment in P-limited systems. The eco-physiological responses shown here help further our understanding of the mechanism of N and P colimitation and underscore the importance of dual N and P reduction in controlling cyanobacterial blooms.

Metal-free carbon catalysts with excellent conduction performance have drawn much research attention in reduction reactions. Herein, a N, B co-doped carbon catalyst with high pyrrolic N proportion (35.75%) and excellent surface area (1409 m2/g) was successfully prepared viacarbonizing covalent organic framework materials (COFs) containing N and B atoms assisted by ZnCl2molten salt. The presence of ZnCl2maintains the micropore structure of COFs to provide high specific surface areas and abundant lattice defects for carbon materials. In addition, electron-withdrawing B heteroatom further facilitates the formation of pyrrolic N at defect sites by modifying the electronic structure of carbon network. The tuning of surface areas and active N species in carbon catalysts successfully improve the selective hydrogenation of nitrobenzene to aniline. The optimized carbon material exhibits excellent nitrobenzene conversion (99.9%) and aniline selectivity (>99%) within 15 min, as well as excellent substrate suitability. This work provides a certain guiding for the design and application of metal-free catalysis.

The tool flank wear progresses rapidly in edge trimming of carbon fiber reinforced polymer (CFRP) components, affecting the machined surface quality and process efficiency. This paper presents a tool wear prediction method considering the unique interlaminar effect of the multi-directional (MD) CFRP in the edge trimming process. The experimental results show that different laminar configurations of MD CFRP change the tool wear progression of unidirectional (UD) plies at specific fiber orientations. The interlaminar effects from the adjacent layers with different fiber orientations are explained by their varying supporting strengths on the target layer due to the change of bouncing back height. Therefore, the interlaminar effect from two sides of a UD ply is not a simple summation of the contributions by the individual side. The machined surface roughness of unidirectional ply varies up to 30 % due to the interlaminar effect. A long short-term memory (LSTM) - back propagation (BP) network is developed to predict tool wear length, including the effect of different interlaminar configurations. With the proposed model, the effect of the interlaminar configurations on tool wear progression in edge trimming of MD CFRP is predicted quantitatively. The prediction of the wear length progression based on the developed machine learning model is validated by the experimental results.

Abstract:Microcystisblooms occur frequently in eutrophic lakes, and they are composed of many different-sized colonies. Many studies have addressed the competitive advantage of colony size, e.g. colony buoyancy regulation mechanism, low nutrient stress tolerance, low irradiance stress; however, studies are lacking for growth strategies of different-sized Microcystiscolonies responding to photosynthetic regulation. This study compared photosynthetic activities and photosynthetic pigment composition of different-sized Microcystis. The results showed that the photosynthetic activity caused a V-shaped curve as colony size increased, i.e. medium-sized colonies (125–400 μm) had the lowest photosynthetic activity. The higher photosynthetic activity of small colonies (< 125 μm) was probably caused by the higher light-harvesting efficiency of phycobilisomes (PBS) and a relatively low nonphotochemical quenching (qN). The high photosynthesis of large colonies (> 400 μm) was attributed to the high efficiency of energy transition of the electron transport chains in photosystem II. Also, large colonies tolerated high irradiance stress because of their high qN, which was related to high cell quotas of PBS. All these results suggested that both small and large colonies had their own ecological adaptation strategies when they were suspended at different water layers, providing an explanation for how Microcystissurvives adverse natural conditions, grows rapidly and forms serious surface blooms.

The effects of organic matter in sediment on phosphorus release were studied by field investigations in eight Chinese shallow freshwater lakes with different trophic status and a laboratory experiment. The sediment organic matter content paralleled the trophic status, ranging from 6.1 to 173.0 g kg-;1 (dry weight), with the mean value of 63.1 g kg-1 (dry weight). It was positively proportional to soluble reactive phosphorus concentration in the interstitial water in a form of exponential function, but inversely related to the sediment Fe/P ratio. The sediment alkaline phosphatase activity was significantly related not only to the organic matter content (r = 0.829, P < 0.01, n = 120), but also to the soluble reactive phosphorus concentration in interstitial water (r = 0.454, P < 0.01, n = 42). In the laboratory experiment, the addition of organic matter (dry materials of an aquatic macrophyte) into the sediment significantly enhanced alkaline phosphatase activity and soluble reactive phosphorus release. However, in the treatment with organic matter added and aeration, this release was generally prevented in spite of an increase in APA. Hence, sediment organic matter can effectively accelerate phosphorus release by enzymatic hydrolysis and anaerobic desorption. The latter mechanism seems to be more important.

Nanometric and monodisperse starch acetate nanospheres can be prepared through a simple procedure of nanoprecipitation, by the dropwise addition of water to an acetone solution of starch acetate, without any stabilizing agent. This is the first report of the preparation of starch-based nanospheres by this method. The size of the nanospheres obtained can be easily controlled by a number of simple and efficient modifications, i.e., through regulation of the polymer concentration in acetone, the proportions of the water and organic phases, and the molecular weight and degree of substitution of the starch esters. A number of reasons are suggested to explain the observed transitions in the particle size. Fluorescence spectroscopic studies proved that these types of nanospheres could be potentially used for the encapsulation of hydrophobic drugs.

The AC electrokinetic technology, such as AC electroosmosis, induced-charged electroosmosis, dielectrophoresis, etc., can precisely manipulate trace fluids and has been widely used in lab on a chip. However, the power supplies used in AC electrokinetic experiments are mostly function generators or other large-scare instruments, which is an obstacle to portability. Encouragingly, triboelectric nanogenerator (TENG) with the characteristics of portable, green, and simple structure is a potential opportunity for AC electrokinetic microfluidic operation. We have designed a self-powered AC electrokinetic microfluidic system based on vertical contact-separation mode TENG for the first time. The TENG, as a power supply, costs only 2 cents and maintains excellent output performance after millions of working cycles. Through the combination of TENG and microfluidic chip, this system successfully realizes AC electroosmotic flow and induced-charged electroosmotic flow in the microchannel and completes the effective mixing of two fluids at low frequencies (<10 Hz). Furthermore, we have achieved precise control of particle behavior, including focusing, deflection, and separation under manual operation. Therefore, the self-powered AC electrokinetic microfluidic system designed in this work not only expands the application fields of TENG but also provides a new power solution for AC electrokinetic microfluidic operation. This system is expected to get rid of the need for large-scale power supply in traditional methods and has broad application prospects in the fields of portable detection, micro-reaction, and micro-bioanalysis.

The crystallization kinetics of biodegradable poly(butylene succinate‐co‐adipate) (PBS/A) copolyester was investigated by using differential scanning calorimetry (DSC) and polarized optical microscopy (POM), respectively. The Avrami and Ozawa equations were used to analyze the isothermal and nonisothermal crystallization kinetics, respectively. By using wide‐angle X‐ray diffraction (WAXD), PBS/A was identified to have the same crystal structure with that of PBS. The spherulitic growth rates of PBS/A measured in isothermal conditions are very well comparable with those measured by nonisothermal procedures (cooling rates ranged from 0.5 to 15 °C/min). The kinetic data were examined with the Hoffman–Lauritzen nucleation theory. The observed spherulites of PBS/A with different shapes and textures strongly depend on the crystallization temperatures. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 3231–3241, 2005

The crystallization behavior of nylon 1212, irradiated at 60Co γ‐rays (50 kGy), was studied by a rheometer, polarized optical microscopy (POM), and differential scanning calorimeter (DSC). The results showed that irradiated nylon 1212 samples exhibited abnormal crystallization behavior during the crystallization process: The Avrami exponent n was calculated and was found to be in the range from 2.06–2.41 for isothermal crystallization, and from 2.67–4.91 for nonisothermal crystallization; the spherulite morphology also changed largely by polarized optical microscopy (POM); the crystallization activation energy ΔE for isothermal and nonisothermal crystallization process of irradiated nylon 1212 are determined to be 57.4 kJ/mol and 78.65 kJ/mol, respectively, which are lower than that of nonirradiated nylon 1212. At the same time, a new method by a combination of the Avrami and Ozawa equations was successfully applied to analyze the noncrystallization process of irradiated nylon 1212. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 2326–2333, 2005

The results obtained for poly(butylene succinate) (PBS) after 60Co γ‐ray irradiation, studied by wide‐angle X‐ray diffraction (WAXD), differential scanning calorimeter (DSC) and polarizing optical microscopy (POM), revealed that the degree of crystallinity, melting temperature and enthalpy decreased with increasing irradiation dose, but that the crystal structure of PBS did not vary when compared to non‐irradiated PBS. By using Scherrer equation, small changes occurred in the crystal sizes of L020, L110 and L111. The spherulitic morphology of PBS was strongly dependent on irradiation dose and changed significantly at higher irradiation dosages. The crystallization kinetics of PBS indicated that the Avrami exponent (n) for irradiated PBS was reduced to 2.3, when compared to non‐irradiated PBS (3.3). Copyright © 2004 Society of Chemical Industry