查看更多>>摘要：In recent years,significant progress has been made in both three-dimensional(3D)printing technologies and the exploration of silk as an ink to produce biocompatible constructs.Combined with the unlimited design potential of 3D printing,silk can be processed into a broad range of functional materials and devices for various biomedical applications.The ability of silk to be processed into various materials,including solutions,hydrogels,particles,microspheres,and fibers,makes it an excellent candidate for adaptation to different 3D printing techniques.This review presents a didactic overview of the 3D print-ing of silk-based materials,major categories of printing techniques,and their prototyping mechanisms and structural features.In addition,we provide a roadmap for researchers aiming to incorporate silk printing into their own work by summarizing promising strategies from both technical and material aspects,to relate state-of-the-art silk-based material processing with fast-developing 3D printing tech-nologies.Thus,our focus is on elucidating the techniques and strategies that advance the development of precise assembly strategies for silk-based materials.Precise printing(including high printing resolu-tion,complex structure realization,and printing fidelity)is a prerequisite for the digital design capability of 3D printing technology and would definitely broaden the application era of silk,such as complex bio-mimetic tissue structures,vasculatures,and transdermal microneedles.
查看更多>>摘要：Globally,vegetation has been changing dramatically.The vegetation-water dynamic is key to under-standing ecosystem structure and functioning in water-limited ecosystems.Continual satellite monitor-ing has detected global vegetation greening.However,a vegetation greenness increase does not mean that ecosystem functions increase.The intricate interplays resulting from the relationships between veg-etation and precipitation must be more adequately comprehended.In this study,satellite data,for exam-ple,leaf area index(LAI),net primary production(NPP),and rainfall use efficiency(RUE),were used to quantify vegetation dynamics and their relationship with rainfall in different reaches of the Yellow River Basin(YRB).A sequential regression method was used to detect trends of NPP sensitivity to rainfall.The results showed that 34.53％of the YRB exhibited a significant greening trend since 2000.Among them,20.54％,5337％,and 16.73％of upper,middle,and lower reach areas showed a significant positive trend,respectively.NPP showed a similar trend to LAI in the YRB upper,middle,and lower reaches.A notable difference was noted in the distributions and trends of RUE across the upper,middle,and lower reaches.Moreover,there were significant trends in vegetation-rainfall sensitivity in 16.86％of the YRB's middle reaches-14.08％showed negative trends and 2.78％positive trends.A total of 8.41％of the YRB exhibited a marked increase in LAI,NPP,and RUE.Subsequently,strategic locations reliant on the corre-lation between vegetation and rainfall were identified and designated for restoration planning purposes to propose future ecological restoration efforts.Our analysis indicates that the middle reach of the YRB exhibited the most significant variation in vegetation greenness and productivity.The present study underscores the significance of examining the correlation between vegetation and rainfall within the con-text of the high-quality development strategy of the YRB.The outcomes of our analysis and the proposed ecological restoration framework can provide decision-makers with valuable insights for executing rational basin pattern optimization and sustainable management.
查看更多>>摘要：The sustainable recovery and utilization of sludge bioenergy within a circular economy context has drawn increasing attention,but there is currently a shortage of reliable technology.This study presents an innovative biotechnology based on free nitrous acid(FNA)to realize sustainable organics recovery from waste activated sludge(WAS)in-situ,driving efficient nitrogen removal from ammonia rich mature landfill leachate by integrating partial nitrification,fermentation,and denitrification process(PN/DN-F/DN).First,ammonia((1708.5±142.9)mg·L-1)in mature landfill leachate is oxidized to nitrite in the aerobic stage of a partial nitrification coupling denitrification(PN/DN)sequencing batch reactor(SBR),with nitrite accumulation ratio of 95.4％±2.5％.Then,intermediate effluent(NO2--N-(1196.9±184.2)mg·L-1)of the PN/DN-SBR,along with concentrated WAS(volatile solids(VSs)-(15 119.8±2484.2)mg·L-1),is fed into an anoxic reactor for fermentation coupling denitrification pro-cess(F/DN).FNA,the protonated form of nitrite,degrades organics in the WAS to the soluble fraction by the biocidal effect,and the released organics are utilized by denitrifiers to drive NOx-reduction.An ultra-fast sludge reduction rate of 4.89 kg.m-3·d-1 and nitrogen removal rate of 0.46 kg·m-3·d-1 were realized in the process.Finally,F/DN-SBR effluent containing organics is refluxed to PN/DN-SBR for sec-ondary denitrification in the post anoxic stage.After 175 d operation,an average of 19 350.6 mg chem-ical oxygen demand organics were recovered per operational cycle,with 95.2％nitrogen removal and 53.4％sludge reduction.PN/DN-F/DN is of great significance for promoting a paradigm transformation from energy consumption to energy neutral,specifically,the total benefit in equivalent terms of energy was 291.8 kW·h·t-1 total solid.
查看更多>>摘要：The Tibetan Plateau(TP)is the headwater of the Yangtze,Yellow,and the transboundary Yarlung Zangbo,Lancang,and Nujiang Rivers,providing essential and pristine freshwater to around 1.6 billion people in Southeast and South Asia.However,the temperature rise TP has experienced is almost three times that of the global warming rate.The rising temperature has resulted in glacier retreat,snow cover reduction,permafrost layer thawing,and so forth.Here we show,based on the longest observed streamflow data available for the region so far,that changing climatic conditions in the TP already had significant impacts on the streamflow in the headwater basins in the area.Our analysis indicated that the annual average temperature in the headwater basins of these five major rivers has been rising on a trend averaging 038 ℃·decade-1 since 1998,almost triple the rate before 1998,and the change of streamflow has been predominantly impacted by precipitation in these headwater basins.As a result,streamflow in the Yangtze,Yarlung Zangbo,Lancang,and Nujiang River headwater areas is on a decreasing trend with a reduction of flow ranging from 3.0 ×109-5.9×109 m3·decade-1(-9.12％to-16.89％per decade)since 1998.The increased precipitation in the Tangnahai(TNH)and Lanzhou(LZ)Basins contributed to the increase of their streamflows at 8.04％and 14.29％per decade,respectively.Although the increased streamflow in the headwater basins of the Yellow River may ease some of the water resources concerns,the decreasing trend of streamflow in the headwater areas of the southeastern TP region since 1998 could lead to a water crisis in transboundary river basins for billions of people in Southeast and South Asia.
查看更多>>摘要：The patterns of material accumulation in buildings and infrastructure accompanied by rapid urbanization offer an important,yet hitherto largely missing stock perspective for facilitating urban system engineer-ing and informing urban resources,waste,and climate strategies.However,our existing knowledge on the patterns of built environment stocks across and particularly within cities is limited,largely owing to the lack of sufficient high spatial resolution data.This study leveraged multi-source big geodata,machine learning,and bottom-up stock accounting to characterize the built environment stocks of 50 cities in China at 500 m fine-grained levels.The per capita built environment stock of many cities(261 tonnes per capita on average)is close to that in western cities,despite considerable disparities across cities owing to their varying socioeconomic,geomorphology,and urban form characteristics.This is mainly owing to the construction boom and the building and infrastructure-driven economy of China in the past decades.China's urban expansion tends to be more"vertical"(with high-rise buildings)than"horizontal"(with expanded road networks).It trades skylines for space,and reflects a concentration-dispersion-concentration pathway for spatialized built environment stocks development within cities in China.These results shed light on future urbanization in developing cities,inform spatial planning,and support circular and low-carbon transitions in cities.
查看更多>>摘要：Rockburst disasters occur frequently during deep underground excavation,yet traditional concepts and methods can hardly meet the requirements for support under high geo-stress conditions.Consequently,rockburst control remains challenging in the engineering field.In this study,the mecha-nism of excavation-induced rockburst was briefly described,and it was proposed to apply the excavation compensation method(ECM)to rockburst control.Moreover,a field test was carried out on the Qjnling Water Conveyance Tunnel.The following beneficial findings were obtained:Excavation leads to changes in the engineering stress state of surrounding rock and results in the generation of excess energy △E,which is the fundamental cause of rockburst.The ECM,which aims to offset the deep excavation effect and lower the risk of rockburst,is an active support strategy based on high pre-stress compensation.The new negative Poisson's ratio(NPR)bolt developed has the mechanical characteristics of high strength,high toughness,and impact resistance,serving as the material basis for the ECM.The field test results reveal that the ECM and the NPR bolt succeed in controlling rockburst disasters effectively.The research results are expected to provide guidance for rockburst support in deep underground projects such as Sichuan-Xizang Railway.
查看更多>>摘要：The development of effective antifreeze peptides to control ice growth has attracted a significant amount of attention yet still remains a great challenge.Here,we propose a novel design method based on in-depth investigation of repetitive motifs in various ice-binding proteins(IBPs)with evolution analysis.In this way,several peptides with notable antifreeze activity were developed.In particular,a designed antifreeze peptide named AVD exhibits ideal ice recrystallization inhibition(IRI),solubility,and biocom-patibility,making it suitable for use as a cryoprotective agent(CPA).A mutation analysis and molecular dynamics(MD)simulations indicated that the Thr6 and Asn8 residues of the AVD peptide are fundamen-tal to its ice-binding capacity,while the Seri 8 residue can synergistically enhance their interaction with ice,revealing the antifreeze mechanism of AVD.Furthermore,to evaluate the cryoprotection potential of AVD,the peptide was successfully employed for the cryopreservation of various cells,which demon-strated significant post-freezing cell recovery.This work opens up a new avenue for designing antifreeze materials and provides peptide-based functional modules for synthetic biology.
查看更多>>摘要：Infections with multidrug-resistant(MDR)Gram-negative bacteria,such as MDR Escherichia coli(E.coli),remain a challenge due to the lack of safe antibiotics and high fatality rates under anti-infection thera-pies.This work presents a form of biomimetic intelligent catalysis inspired by the selective biocatalytic property of macrophages(MΦs),consisting of an intelligent controlling center(a living MΦ)and a Fenton reaction catalyst(Fe3O4@poly(lactic-co-glycolic acid)(PLGA)nanoparticles)for killing MDR E.coli with-out harming normal cells.The MΦ-Fe3O4@PLGA particles(i.e.,the intelligent catalysis particles)exhibit selective biocatalysis activity toward MDR E.coli by producing H2O2 and lipid droplets(LDs).This process activates the lipid metabolism and glycan biosynthesis and metabolism pathways based on the result of RNA sequencing data analysis.The H2O2 further reacts with Fe3O4@PLGA to form highly toxic hydroxyl radicals(·OH),while the LDs contain antimicrobial peptides and can target MDR E.coli.The highly toxic·OH and antimicrobial peptides are shown to combat with MDR E.coli,such that the antibacterial effi-ciency of the MΦ-Fe3O4@PLGA particles against MDR E.coli is 99.29％±0.31％in vitro.More importantly,after several passages,the intelligent catalysis function of the MΦ-Fe3O4@PLGA particles is well main-tained.Hence,the concept of biomimetic intelligent catalysts displays potential for treating diseases other than infections.
查看更多>>摘要：Transplantation of probiotics to the intestine can positively regulate the gut microbiota,thereby promot-ing the immune system and treating various diseases.However,the harsh gastrointestinal environment and short retention time in the gastrointestinal tract significantly limit the bioavailability and intestinal colonization of probiotics.Herein,we present a double-layer polysaccharide hydrogel(DPH)in the form of a double-layer structure composed of a carboxymethyl cellulose(CMCL)supramolecular inner layer and a dialdehyde alginate(DAA)cross-linked carboxymethyl chitosan(CMCS)outer layer.This double-layer structure allows DPH to encapsulate and deliver probiotics in a targeted manner within the body.In the stomach,the cage structure of the DPH is closed,and the outer layer absorbs surrounding liquids to form a barrier to protect the probiotics from gastric fluids.In the intestine,the cage structure opens and disintegrates,releasing the probiotics.Thus,DPH endows probiotics with excellent intestine-targeted delivery,improved oral bioavailability,enhanced gastrointestinal tract tolerance,and robust mucoadhe-sion capacity.The encapsulated probiotics exhibit almost unchanged bioactivity in the gastrointestinal tract before release,as well as improved oral delivery.In particular,probiotics encapsulated by DPH exhi-bit 100.1 times higher bioavailability and 10.6 times higher mucoadhesion than free probiotics in an ani-mal model 48 h post-treatment.In addition,with a remarkable ability to survive and be retained in the intestine,probiotics encapsulated by DPH show excellent in vitro and in vivo competition with pathogens.Notably,DAA-mediated dynamic crosslinking not only maintains the overall integrity of the hydrogels but also controls the release timing of the probiotics.Thus,it is expected that encapsulated substances(probiotics,proteins,etc.)can be delivered to specific sites of the intestinal tract by means of DPH,by con-trolling the dynamic covalent crosslinking.
查看更多>>摘要：The United Nations(UN)'s call for a decade of"ecosystem restoration"was prompted by the need to address the extensive impact of anthropogenic activities on natural ecosystems.Marine ecosystem restoration is increasingly necessary due to increasing habitat degredation in deep waters(＞200 m depth).At these depths,which are far beyond those accessible by divers,only established and emerging robotic platforms such as remotely operated vehicles(ROVs),autonomous underwater vehides(AUVs),landers,and crawlers can operate through manipulators and multiparametric sensor arrays(e.g,optoa-coustic imaging,omics,and environmental probes).The use of advanced technologies for deep-sea ecosystem restoration can provide:① high-resolution three-dimensional(3D)imaging and acoustic mapping of substrates and key taxa,② physical manipulation of substrates and key taxa,③ real-time supervision of remote operations and long-term ecological monitoring,and ④ the potential to work autonomously.Here,we describe how robotic platforms with in situ manipulation capabilitiesand pay-loads of innovative sensors could autonomously conduct active restoration and monitoring across large spatial scales.We expect that these devices will be particularly useful in deep-sea habitats,such as① reef-building cold-water corals,② soft-bottom bamboo corals,and ③ soft-bottom fishery resources that have already been damaged by offshore industries(i.e.,fishing and oil/gas).
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