Detoxification strategy of Microcystis aeruginosa to the toxicity of Cd(Ⅱ):role of EPS in alleviating toxicity

Although many studies have found that cadmium(Cd)can be toxic to microalgae,only a few reports focused on the role of extracellular polymeric substances(EPS)in Cd(Ⅱ)detoxification.The biochemical and physiological endpoints of Microcystis aeruginosa,including the composition and functional groups of soluble EPS(SL-EPS),loosely bound EPS(LB-EPS),and tightly bound EPS(TB-EPS),were detected to elucidate the toxicity and detoxification mechanisms of Cd(Ⅱ)for cyanobacteria.Toxicological and physiological assays on M.aeruginosa showed that the 0.25-mg/L Cd(Ⅱ)resulted in a larger inhibition on growth and F_(v)/F_(m).Nevertheless,Cd(Ⅱ)significantly induced much higher contents of superoxide dismutase(SOD),intracellular microcystin LR(MC-LR),extracellular MC-LR,and EPS.Scanning electron microscopy with energy dispersive X-ray spectroscopy confirmed that Cd(Ⅱ)was absorbed into the EPS layer.Fourier transform infrared spectrum analysis revealed that the functional groups bound with Cd(Ⅱ)of algae biomass,SL-EPS,LB-EPS,and TB-EPS were somewhat different.The C=O/C=N groups ofδ-lactam or protein were their prominent functional groups,suggesting that amide or proteins in the EPS played a key role in the adsorption in Cd(Ⅱ).The concentration of 0.25 mg/L of Cd(Ⅱ)may change the chemical structure of EPS by altering the production of protein-like substances containing tryptophan.This study indicated that M.aeruginosa could detoxify Cd(Ⅱ)stress via induction of antioxidant capacity(higher SOD activity and MC synthesis),EPS production,and modification in chemical structure of EPS.

A Polyvinyl Alcohol/Acrylamide Hydrogel with Enhanced Mechanical Properties Promotes Full-Thickness Skin Defect Healing by Regulating Immunomodulation and Angiogenesis Through Paracrine Secretion

Hydrogel-based tissue-engineered skin has attracted increased attention due to its potential to restore the structural integrity and functionality of skin.However,the mechanical properties of hydrogel scaffolds and natural skin are substantially different.Here,we developed a polyvinyl alcohol(PVA)/acrylamide based interpenetrating network(IPN)hydrogel that was surface modified with polydopamine(PDA)and termed Dopa-gel.The Dopa-gel exhibited mechanical properties similar to native skin tissue and a superior ability to modulate paracrine functions.Furthermore,a tough scaffold with tensile resistance was fabricated using this hydrogel by three-dimensional printing.The results showed that the interpenetration of PVA,alginate,and polyacrylamide networks notably enhanced the mechanical properties of the hydrogel.Surface modification with PDA endowed the hydrogels with increased secretion of immunomodulatory and proangiogenic factors.In an in vivo model,Dopa-gel treatment accelerated wound closure,increased vascularization,and promoted a shift in macrophages from a proinflammatory M1 phenotype to a prohealing and anti-inflammatory M2 phenotype within the wound area.Mechanistically,the focal adhesion kinase(FAK)/extracellular signal-related kinase(ERK)signaling pathway may mediate the promotion of skin defect healing by increasing paracrine secretion via the Dopa-gel.Additionally,proangiogenic factors can be induced through Rho-associated kinase-2(ROCK-2)/vascular endothelial growth factor(VEGF)-mediated paracrine secretion under tensile stress conditions.Taken together,these findings suggest that the multifunctional Dopa-gel,which has good mechanical properties similar to those of native skin tissue and enhanced immunomodulatory and angiogenic properties,is a promising scaffold for skin tissue regeneration.

Safety-Critical Trajectory Tracking for Mobile Robots With Guaranteed

Dear Editor,This letter considers a collision-free trajectory tracking problem for performance-guaranteed mobile robots(MRs)subject to obstacles.We propose a safety-critical performance-guaranteed trajectory tracking method based on control barrier functions(CBFs).First,an auxiliary system is established to generate the non-negative signals for inflexible bounds such that the performance constraints are not violated when avoiding obstacles.

Rational construction of Ag@MIL-88B(V)-derived hierarchical porous Ag-V_(2)O_(5) heterostructures with enhanced diffusion kinetics and cycling stability for aqueous zinc-ion batteries

With the advantages of the multiple oxidation states and highly open crystal structures,vanadium-based composites have been considered as the promising cathode materials for aqueous zinc-ion batteries(ZIBs).However,the inherent inferior electrical conductivity,low specific surface area,and sluggish Zn^(2+)diffusion kinetics of the traditional vanadium-based oxides have greatly impeded their development.Herein,a novel hierarchical porous spindle-shaped Ag-V_(2)O_(5) with unique heterostructures was rationally designed via a simple MOF-assisted synthetic method and applied as stable cathode for aqueous ZIBs.The high specific surface area and hierarchically porous superstructures endowed Ag-V_(2)O_(5) with sufficient electrochemical active sites and shortened the diffusion pathways of Zn^(2+),which was beneficial to accelerate the reversible transport of Zn^(2+)and deliver a high specific capacity(426 mA h g^(-1) at 0.1 A g^(-1) and 96.5%capacity retention after 100 cycles).Meanwhile,the self-built-in electric fields at the heterointerface of Ag-V_(2)O_(5) electrode could strengthen the synergistic coupling interaction between Ag and V_(2)O_(5),which can effectively enhance the electric conductivity and maintain the structural integrity,resulting in superb rate capability(326.1 mA h g^(-1) at 5.0 A g^(-1))and remarkable cycling stability(89.7%capacity retention after 2000 cycles at 5.0 A g^(-1)).Moreover,the reversible Zn^(2+)storage mechanism was further investigated and elucidated by kinetics analysis and DFT calculations.

Environmental hypoxia induces apoptosis in large yellow croaker Larimichthys crocea via both intrinsic and extrinsic pathways

Hypoxia has become an unfavorable factor affecting the sustainable development of the large yellow croaker Larimichthys crocea,an economically important mariculture fish in China.Apoptosis is a consequence of hypoxia on fish.However,the effects of hypoxia stress on apoptosis in L.crocea remain largely unknown.We investigated the effect of environmental hypoxia on apoptosis in L.crocea.Results show that hypoxia induced apoptosis in L.crocea both in vivo and in vitro.The mitochondrial membrane potential was significantly reduced in large yellow croaker fry(LYCF)cells.The expression levels of Bcell lymphoma/leukemia-2(Bcl-2)m RNA and protein were also significantly decreased in the liver and LYCF cells during 96 h and 48 h of hypoxia stress,respectively,whereas the expression level of Bcl-2 associated X(Bax)mRNA,Casp3 mRNA,and activity of caspase-3/7/9 were significantly increased,indicating that hypoxia induced caspase-dependent intrinsic apoptosis in L.crocea.The expression level of the apoptosis-inducing factor(AIF)protein was significantly increased in the liver and LYCF cells.The level of AIF protein was significantly decreased in the cytoplasm but increased in the nuclei of L.crocea,demonstrating that hypoxia induced the AIF-mediated caspase-independent intrinsic apoptosis.In addition,the activity of caspase-8 was significantly increased,indicating that hypoxia stress induced extrinsic apoptosis in L.crocea.Therefore,hypoxia induced apoptosis in L.crocea through both the intrinsic and extrinsic pathways.The present study accumulated basic biological information to help elucidate the mechanism of hypoxia response in marine fish.

调控尖晶石Co^(3+)和Ni^(3+)表面密度来提高催化甲烷氧化活性（英文）

天然气资源丰富、价格低廉,因而被广泛用作燃料.天然气的主要成分是甲烷,未燃烧完的甲烷所产生的温室效应是二氧化碳的21倍,所带来的环境问题引起越来越多的研究者关注.但甲烷是最稳定的非极性有机小分子,C–H键能高达434 k J/mol,大多数催化剂很难将其在很低的温度在完全转化.C?H键的活化解离是催化甲烷燃烧最关键的一步,而活化C–H键方式主要有两大类:(1)均裂活化机制,一般用在贵金属催化剂上;(2)异裂活化机制,往往发生在过渡金属氧化物上.比较而言,贵金属催化剂,尤其是Pd,往往具有更优异的低温催化活性,但价格昂贵,从而限制了其广泛使用.因此,开发更加高效的非贵金属催化剂用于废气中未转化的甲烷完全氧化是亟待解决的问题.含有Co和Ni的尖晶石氧化物具有良好的催化甲烷燃烧活性,有望代替贵金属催化剂,但要求在低于400°C完全转化,仍具有一定挑战.另一方面,Ni^(3+)和Co^(3+)哪个是活性中心,还具有一定争议.因此,我们通过水热法和共沉淀法合成一系列表面暴露不同数目的Ni^(3+)和Co^(3+)来探究表面高氧化态Co和Ni跟活性之间的关系.XRD和TEM结果表明,相比于水热法合成的水热法合成的发生明显的晶格收缩现象,这是由于在尖晶石体相中大量小半径Ni^(3+)(0.053 nm)取代了大半径Co^(3+)(0.055 nm)所致.同时还发现,水热合成的尖晶石具有多孔纳米片层结构,相比于共沉淀法合成的尖晶石具有更大的比表面积,催化活性也更高.XPS分析发现,催化甲烷燃烧的活性随着表面含量增加而提高.结合文献分析和本文的实验结果推测,表面的Ni^(3+)和Co^(3+)都可作为解离C?H键的活性中心.水热60小时合成的纳米片表面的数量最多,所以具有最优异的催化性能,大约在280°C甲烷转化50%.当加入10%(体积比)的水,在高空速工况下对催化活性影响不大,主要是因为长时间水热合成的尖晶石表面缺陷少,对水的吸附弱,这可通过O 1s图谱得到印证.总之,这些研究结果能够给甲烷活化和开发更加高效和低成本催化剂一些启示.

A novel PdNi/Al_2O_3 catalyst prepared by galvanic deposition for low temperature methane combustion

Galvanic deposition method was used to prepare the Pd/Ni-Al2O3-GD catalyst for the combustion of methane under lean conditions. The new catalyst and compared catalysts （Pd/Al2O3-IW, Pd-Ni/Al2O3-IW, Pd/Ni-Al2O3-IW） prepared by incipient wetness impregnation were characterized by N2-physisorption, XRD and TEM to clarify particle size and size distribution of palladium species. Combined O2-TPD and XPS results with the catalytic data, it shows that the surface palladium species with low valence exhibits better combustion performance due to their stronger interaction with support. The results indicate that the galvanic deposition method is an effective route to prepare efficient catalyst for methane combustion, and it also provides useful information for improving the present commercial catalyst.

A Physical Layer Algorithm for Estimation of Number of Tags in UHF RFID Anti-Collision Design

A priori knowledge of the number of tags is crucial for anti-collision protocols in slotted UHF RFID systems.The number of tags is used to decide optimal frame length in dynamic frame slotted ALOHA(DFSA)and to adjust access probability in random access protocols.Conventional researches estimate the number of tags in MAC layer based on statistics of empty slots,collided slots and successful slots.Usually,a collision detection algorithm is employed to determine types of time slots.Only three types are distinguished because of lack of ability to detect the number of tags in single time slot.In this paper,a physical layer algorithm is proposed to detect the number of tags in a collided slot.Mean shift algorithm is utilized,and some properties of backscatter signals are investigated.Simulation results verify the effectiveness of the proposed solution in terms of low estimation error with a high SNR range,outperforming the existing MAC layer approaches.

Influence of Wall Effect on Comprehensive Controllability for Ducted Fan Aircraft

A novel coaxial ducted fan structure aircraft is proposed to enable the aircraft near vertical walls at high altitudes.The state space equation of the system can be obtained by correlation deduction and identification of the whole prototype model.Based on the duct test bench experiment and computational fluid dynamics(CFD)simulation analysis,the expressions between the different distances dWE from the rotor center of the prototype to the wall and the thrust,reaction torque,and tilting moment of the system under hovering conditions are obtained.The influence of the wall effect of the prototype is incorporated into the system model to analyze the relationship between distance dWE and the comprehensive controllability of the system.The results show that the system comprehensive controllability vector of other channels changes little with the decrease of the distance dWE,and only the controllability vector of the rolling channel increases significantly.At the same time,the tilting moment also increases significantly,which strengthens the tendency of the prototype to tilt towards the wall.

A Project-Based Sustainability Rating Tool for Pavement Maintenance

路面需要养护,以防止其过度损坏,或使其恢复性能,然而在许多情况下,路面养护的重要性并没有得到足够的重视,它经常会被忽视或被作为低优先级处理。目前大多数的养护活动都存在预算问题,且只专注于清理损坏的路段。延期的路面养护会对环境和社会产生影响,因此可能会影响与养护相关的成本。可持续性评级工具是列举、解释和评估此类影响的好方法。目前已经为路面设计了多种评级工具,但是,路面养护与新建、扩建、改造路面等工程相比有不同的特点。本研究回顾了9种路面可持续性评级工具,但这些工具没有一个可以完全描述养护特征,或者可以直接用于评估养护项目。因而,一个新型的用于路面养护的可持续性评级工具开始发展,这个新的工具可以用来评估单独的养护项目,并且可以提高公众对于路面养护重要性的认识。本文对其细节进行了描述,并通过示例展示了其评估过程和结果。

Large contributions of emission reductions and meteorological conditions to the abatement of PM_(2.5)in Beijing during the 24th Winter Olympic Games in 2022

To guarantee the blue skies for the 2022 Winter Olympics held in Beijing and Zhangjiakou from February 4 to 20,Beijing and its surrounding areas adopted a series of emission control measures.This provides an opportunity to determine the impacts of large-scale temporary control measures on the air quality in Beijing during this special period.Here,we applied the WRF-CMAQ model to quantify the contributions of emission reduction measures and meteorological conditions.Results show that meteorological conditions in 2022 decreased PM_(2.5)in Beijing by 6.9 and 11.8μg/m^(3)relative to 2021 under the scenarios with and without emission reductions,respectively.Strict emission reduction measures implemented in Beijing and seven neighboring provinces resulted in an average decrease of 13.0μg/m^(3)(-41.2%)in PM_(2.5)in Beijing.Over the entire period,local emission reductions contributed more to good air quality in Beijing than nonlocal emission reductions.Under the emission reduction scenario,local,controlled regions,other regions,and boundary conditions contributed 47.7%,42.0%,5.3%,and 5.0%to the PM_(2.5)concentrations in Beijing,respectively.The results indicate that during the cleaning period with the air masses from the northwest,the abatements of PM_(2.5)were mainly caused by local emission reductions.However,during the potential pollution period with the air masses from the east-northeast and west-southwest,the abatements of PM_(2.5)were caused by both local and nonlocal emission reductions almost equally.This implies that regional coordinated prevention and control strategies need to be arranged scientifically and rationally when heavy pollution events are forecasted.

The origin and evolution of salicylic acid signaling and biosynthesis in plants

Salicylic acid(SA)plays a pivotal role in plant response to biotic and abiotic stress.Several core SA signaling regulators and key proteins in SA biosynthesis have been well characterized.However,much remains unknown about the origin,evolution,and early diversification of core elements in plant SA signaling and biosynthesis.In this study,we identified 10 core protein families in SA signaling and biosynthesis across green plant lineages.We found that the key SA signaling receptors,the nonexpresser of pathogenesis-related(NPR)proteins,originated in the most recent common ancestor(MRCA)of land plants and formed divergent groups in the ancestor of seed plants.However,key transcription factors for SA signaling,TGACG motif-binding proteins(TGAs),originated in the MRCA of streptophytes,arguing for the stepwise evolution of core SA signaling in plants.Different from the assembly of the core SA signaling pathway in the ancestor of seed plants,SA exists extensively in green plants,including chlorophytes and streptophyte algae.However,the full isochorismate synthase(ICS)-based SA synthesis pathway was first assembled in the MRCA of land plants.We further revealed that the ancient abnormal inflorescence meristem 1(AIM1)-basedβ-oxidation pathway is crucial for the biosynthesis of SA in chlorophyte algae,and this biosynthesis pathway may have facilitated the adaptation of early-diverging green algae to the high-light-intensity environment on land.Taken together,our findings provide significant insights into the early evolution and diversification of plant SA signaling and biosynthesis pathways,highlighting a crucial role of SA in stress tolerance during plant terrestrialization.

气候变化驱动湖泊快速变暖和热浪增加

气候变化导致的湖泊表层水体变暖和热浪增加可能严重威胁湖泊生态系统.由于大尺度模拟时,湖泊模型精度受限,故对湖泊水温变化的准确量化依然存在不确定性.本研究以中国湖泊为例,采用了一种耦合卫星观测水温和湖泊物理模型的方法模拟了1980-2100年间的水温,并探索了水温在多方面的变化.研究发现1980-2021年间中国湖泊表层水温以0.11℃/10a的速率上升,约为使用单独湖泊模型模拟结果的一半.湖泊水温在不同季节、不同地区的非对称增温导致水温的春夏季季节性在中国东部平原湖泊减弱,在高原湖泊增强.伴随湖泊水温的长期上升趋势,湖泊热浪的持续时间平均每10年延长7.7天.在温室气体高排放情景下,21世纪末湖泊表层水温的气候态年均值相比历史时期将增加2.2℃热浪的年持续时间将增加197天.湖泊物理环境的剧变意味着湖泊将面临严重的人类活动压力,这会进一步威胁水生生态系统的生物多样性和人类健康.

罕见极端高温事件导致中国湖泊急剧变暖

在气候变化背景下,全球极端事件近年来显著增加,严重威胁湖泊生态系统健康及生态服务功能.本研究基于2000~2022年MODIS卫星遥感数据,量化了2022年罕见极端高温事件对我国湖泊的影响.结果表明,该极端高温事件导致中国湖泊表层水温平均升高了1.63℃,远超过去20年的增温幅度.其中,淮河流域和西南诸河流域湖泊受此影响最为明显,分别升高了2.01和1.81℃.不仅如此,该事件引发了长江流域严重干旱,造成鄱阳湖水位下降了55.07%、面积减少了73.32%,从而导致鱼类等水生生物大量死亡、鸟类失去栖息地,多地饮用水短缺.

Tuning the crystallinity of MnO_(2) oxidant to achieve highly efficient pollutant degradation

Manganese dioxide(MnO_(2)), a commonly find oxidant in both natural environment and industrial application, plays a crucial role for various organic compound degradation. Tuning the MnO_(2) crystal structure is a cost-effective strategy to boost the oxidation reactions, where the challenge remains due to lacking indepth investigation of the crystal properties. Herein, MnO_(2) with different crystalline structures(x-MnO_(2))including α-, β-and δ-was prepared through the hydrothermal synthesis for a typical organic pollutant removal. The structural and degradation analysis indicated that the oxidation capacity was originated from Mn^(3+) and oxygen vacancies(OVs). The intrinsic relationships between oxidation performance and other physiochemical properties such as morphology and electrochemistry were thoroughly discussed,and positive correlations between oxidation capacity and electrochemical properties were found which eventually led to excellent oxidation performance via modulating the above-mentioned properties. Moreover, the K^(+) content was determined to be the most crucial role in manipulating the structure properties.This work offers a crystal-level insight into the relationship between the crystal structure and oxidative property, promoting rational design of highly efficient oxidant.

SR-AFU: super-resolution network using adaptive frequency component upsampling and multi-resolution features

Image super-resolution (SR) is one of the classic computer vision tasks. This paper proposes a super-resolution network based on adaptive frequency component upsampling, named SR-AFU. The network is composed of multiple cascaded dilated convolution residual blocks (CDCRB) to extract multi-resolution features representing image semantics, and multiple multi-size convolutional upsampling blocks (MCUB) to adaptively upsample different frequency components using CDCRB features. The paper also defines a new loss function based on the discrete wavelet transform, making the reconstructed SR images closer to human perception. Experiments on the benchmark datasets show that SR-AFU has higher peak signal to noise ratio (PSNR), significantly faster training speed and more realistic visual effects compared with the existing methods.

Materials genome strategy for metallic glasses

Metallic glasses(MGs)have attracted extensive attention in the past decades due to their unique chem-ical,physical and mechanical properties promising for a wide range of engineering applications.A thor-ough understanding of their structure-property relationships is the key to the development of novel MGs with desirable performance.New strategies,as proposed by Materials Genome Initiative(MGI),construct a new paradigm for high-throughput materials discovery and design,and are being increas-ingly implemented in the search of new MGs.While a few reports have summarized the application of high-throughput and/or machine learning techniques,a comprehensive assessment of materials genome strategies for developing MGs is still missing.Herein,this paper aims to present a timely overview of key advances in this fascinating subject,as well as current challenges and future opportunities.A holistic approach is used to cover the related topics,including high-throughput preparation and characterization of MGs,and data-driven machine learning strategies for accelerating the development of novel MGs.Fi-nally,future research directions and perspectives for MGI-assisted design of MGs are also proposed and surmised.

拉花松解技术在关节外内翻畸形全膝置换术的应用

目的探索在关节外膝内翻畸形全膝关节置换术(TKA)中应用拉花松解技术(pie-crusting)可矫正的内翻程度并评估疗效。方法本研究回顾2018年11月至2020年6月在赤峰市医院收治的内翻膝TKA中应用pie-crusting技术40例,测量股骨远端机械外侧角(mLDFA)、胫骨近端机械内侧角(MPTA)、关节线相交角(JLCA)、机械轴偏向(MAD)、关节内外整体内翻角[180°减去髋-膝-踝角(HKA)],评估内翻来源、内翻程度、下肢力线。比较手术前后美国特种外科医院(HSS)膝关节评分、疼痛视觉模拟量表(VAS)评分、膝关节活动度(ROM),采用配对样本t检验和Wilcoxon符号秩和检验评估疗效。结果本组TKA中应用pie-crusting技术40例均伴有膝关节内翻畸形,术前mLDFA(92.7±3.1)°;MPTA(74.7±2.6)°;关节内外整体内翻角(23.1±3.5)°。比较手术前后HSS评分(t=-93.4)、VAS评分(Z=-5.57)、ROM(t=-37.1)、MAD(t=64.8)差异均有统计学意义(均为P<0.05)。结论内翻膝TKA中应用pie-crusting技术,关节内外整体内翻角<29°可应用该技术恢复关节平衡和下肢力线,关节外畸形在关节内矫正,疗效确切且安全。

Phase recovery and holographic image reconstruction using deep learning in neural networks

Phase recovery from intensity-only measurements forms the heart of coherent imaging techniques and holography.In this study,we demonstrate that a neural network can learn to perform phase recovery and holographic image reconstruction after appropriate training.This deep learning-based approach provides an entirely new framework to conduct holographic imaging by rapidly eliminating twin-image and self-interference-related spatial artifacts.This neural network-based method is fast to compute and reconstructs phase and amplitude images of the objects using only one hologram,requiring fewer measurements in addition to being computationally faster.We validated this method by reconstructing the phase and amplitude images of various samples,including blood and Pap smears and tissue sections.These results highlight that challenging problems in imaging science can be overcome through machine learning,providing new avenues to design powerful computational imaging systems.

PhaseStain:the digital staining of label-free quantitative phase microscopy images using deep learning

Using a deep neural network,we demonstrate a digital staining technique,which we term PhaseStain,to transform the quantitative phase images(QPI)of label-free tissue sections into images that are equivalent to the brightfield microscopy images of the same samples that are histologically stained.Through pairs of image data(QPI and the corresponding brightfield images,acquired after staining),we train a generative adversarial network and demonstrate the effectiveness of this virtual-staining approach using sections of human skin,kidney,and liver tissue,matching the brightfield microscopy images of the same samples stained with Hematoxylin and Eosin,Jones’stain,and Masson’s trichrome stain,respectively.This digital-staining framework may further strengthen various uses of label-free QPI techniques in pathology applications and biomedical research in general,by eliminating the need for histological staining,reducing sample preparation related costs and saving time.Our results provide a powerful example of some of the unique opportunities created by data-driven image transformations enabled by deep learning.