Dissolvable temporary barrier:a novel paradigm for flexible hydrogel patterning in organ-on-a-chip models

A combination of hydrogels and microfluidics allows the construction of biomimetic three-dimensional(3D)tissue models in vitro,which are also known as organ-on-a-chipmodels.The hydrogel patterningwith awell-controlled spatial distribution is typically achieved by embedding sophisticated microstructures to act as a boundary.However,these physical barriers inevitably expose cells/tissues to a less physiologically relevant microenvironment than in vivo conditions.Herein,we present a novel dissolvable temporary barrier(DTB)strategy that allows robust and flexible hydrogel patterning with great freedom of design and desirable flow stimuli for cellular hydrogels.The key aspect of this approach is the patterning of a water-soluble rigid barrier as a guiding path for the hydrogel using stencil printing technology,followed by a barrier-free medium perfusion after the dissolution of the DTB.Single and multiple tissue compartments with different geometries can be established using either straight or curved DTB structures.The effectiveness of this strategy is further validated by generating a 3D vascular network through vasculogenesis and angiogenesis using a vascularized microtumor model.As a new proof-of-concept in vasculature-on-a-chip,DTB enables seamless contact between the hydrogel and the culture medium in closed microdevices,which is an improved protocol for the fabrication ofmultiorgan chips.Therefore,we expect it to serve as a promising paradigm for organ-on-a-chip devices for the development of tumor vascularization and drug evaluation in the future preclinical studies.

Multidrug dissolvable microneedle patch for the treatment of recurrent oral ulcer

Recurrent oral ulcer is a painful oral mucosal disorder that affects 20%of the world’s population.The lack of a radical cure due to its unknown underlying cause calls for innovative symptomatic treatments.This work reports a hyaluronic acid-based dissolvablemicroneedle patch(ROUMNpatch,short for recurrent oral ulcer microneedle)loaded with dexamethasone acetate,vitamin C and tetracaine hydrochloride for the treatment of recurrent oral ulcers.The ROUMN patch shows enhancement in both the anti-inflammatory effect elicited by dexamethasone and the pro-proliferation effect of vitamin C.In vitro experiments show that ROUMN has a higher efficiency in suppressing lipopolysaccharide(LPS)-induced interleukin-6(IL-6)expression than dexamethasone alone.Cell proliferation and migrationwere also significantly promoted byROUMNcompared to vitamin C alone.The healing-promoting effect of ROUMN was also verified in vivo using an acetic acid-cauterized oral ulcer model in rats.ROUMN as a treatment accelerated the healing process of oral ulcers,shortening the total healing time to 5 days compared with the 7 days required by treatment using watermelon frost,a commonly used over-the-counter(OTC)drug for oral ulcers.The rapid dissolution of the hyaluronic acid-based microneedles and the superior healing-promoting effect of the drug combination could lead to a broad application prospect of the ROUMN patch in the treatment of recurrent oral ulcers.

A review of physicochemical properties of dissolved organic carbon and its impact over mountain glaciers

Investigating the characteristics and transformation of water-soluble carbonaceous matter in the cryosphere regions is important for understanding biogeochemical process in the earth system.Water-soluble carbonaceous matter is a heterogeneous mixture of organic compounds that is soluble in aquatic environments.Despite its importance,we still lack systematic understanding for dissolved organic carbon(DOC)in several aspects including exact chemical composition and physical interactions with microorganisms,glacier meltwater.This review presents the chemical composition and physical properties of glacier DOC deposited through anthropogenic emission,terrestrial,and biogenic sources.We present the molecular composition of DOC and its effect over snow albedo and associated radiative forcings.Results indicate that DOC in snow/ice is made up of aromatic protein-like species,fulvic acid-like materials,and humic acid-like materials.Light-absorbing impurities in surface snow and glacier ice cause considerable albedo reduction and the associated radiative forcing is definitely positive.Water-soluble carbonaceous matter dominated the carbon transport in the high-altitude glacial area.Owing to prevailing global warming and projected increase in carbon emission,the glacial DOC is expected to release,which will have strong underlying impacts on cryosphere ecosystem.The results of this work have profound implications for better understanding the carbon cycle in high altitude cryosphere regions.A new compilation of globally distributed work is required,including large-scale measurements of glacial DOC over high-altitude cryosphere regions,to overcome and address the scientific challenges to constrain climate impacts of light-absorbing impurities related processes in Earth system and climate models.

Reservoir characteristics and controlling factor of tight sandstone in Shuixigou Group in Taibei depression,Turpan-Hami basin

The positive structure belts surrounding the Taibei Sag,Turpan-Hami Basin,have been the main targets for oil and gas exploration for years and are now left with remaining resources scattering in reservoirs adjacent to source rocks in the sag,where the Shuixigou Group with substantial oil and gas potential constitutes the primary focus for near-source exploration.Consequently,characterization of development and key controlling factors of reservoir space becomes a must for future exploration in the area.This study investigates the development traits,genesis,and controlling factors of the Xishanyao and Sangonghe formations in the Shengbei and Qiudong Sub-sags of the Taibei Sag with techniques such as cast thin-section observation,porosity and permeability tests,high-pressure mercury injection,and saturation fluid NMR analysis of reservoir rocks.The findings reveal that the Shuixigou Group in the Taibei Sag consists of lithic sandstone.Reservoirs in the group are mostly poor in terms of physical properties,with undeveloped primary pores dominated by intergranular dissolved pores as a result of a strong compaction.Comparative analysis of key controlling factors of the Sangonghe Formation reveals significant distinctions in sandstone particle size,sand body thickness,genesis and distribution,provenance location,and source rock type between the Qiudong area and Shengbei area.Vertically,the coal seams of the Xishanyao Formation exhibit heightened development with shallower burial depth and lower maturity compared to those of the Sangonghe Formation.Consequently,this environment fosters the formation of organic acids,which have a stronger dissolution effect on minerals to develop secondary dissolution pores,and ultimately resulting in better reservoir physical properties.Overall,the reservoirs within the Qiudong area of the Taibei Sag demonstrate superior characteristics compared to those in the Shengbei area.Furthermore,the reservoir physical properties of the Xishanyao Formation are better than those of the Sangonghe Formation.The research findings will provide valuable guidance for the exploration and development of lithological oil and gas reservoirs within the Taibei Sag.

Near-infrared responsive 5-fluorouracil and indocyanine green loaded MPEG-PCL nanoparticle integrated with dissolvable microneedle for skin cancer therapy

The prevalence of skin cancer is rising along with the rapid population aging in recent years.Traditional therapies,such as surgical treatment,radiotherapy,chemotherapy,photodynamic therapy,and immunotherapy,may accompany serious side effects,limiting their clinical benefits.According to the biological characteristics of skin cancer,we have already established two kinds of synergetic systems of photothermal therapy(microneedle)and chemotherapy,containing gold nanorods(GNR).Although the microneedle system exhibited great potential for skin cancer treatment,the system could be still improved further.So,we designed a near-infrared lightresponsive 5-fluorouracil(5-Fu)and indocyanine green(ICG)loaded monomethoxy-poly(ethylene glycol)-polycaprolactone(MPEG-PCL)nanoparticle(5-Fu-ICG-MPEG-PCL),and then 5-Fu-ICG-MPEG-PCL was integrated with a hyaluronic acid dissolvable microneedle system(HA MN)to get 5-Fu-ICG-MPEG-PCL loaded HA MN for treating skin cancers,including human epidermoid cancer and melanoma.In this system,hyaluronic acid,the microneedle carrier,possesses good skin penetration ability and is approved by FDA as a pharmaceutical adjuvant;5-Fu is recommended by FDA for skin cancer treatment;ICG,a photothermal agent,possesses a strong photothermal ability and is approved by FDA for its use in the human body.We hypothesized that 5-Fu-ICG-MPEG-PCL could be delivered by the dissolvable microneedle through the skin,and the release behavior of the drug in the nanoparticle could be controlled by near-infrared light for achieving a single-dose cure of skin cancer,improving the cure rate of skin cancer and providing a new idea and possibility for the clinical treatment of skin cancer.

Tracing the sources of nutrients through the Tsushima/Korea Strait

The nutrients from the East China Sea(ECS) through the Tsushima/Korea Strait(TS) strongly impact the eco system of the Japan Sea(JS).The complex origins of the Tsushima Warm Current and the various nutrient sources in the ECS result in complex spatial-temporal variations in nutrients in the TS.Using a physical-biological model with a tracking technique,we studied the effects of nutrient sources from the ECS on the TS.Among all the nutrient sources,the Kuroshio has the highest nutrient concentrations in the TS.Its maximum concentration occurs at the bottom,while those of rivers and atmospheric depo sition occur at the surface,and that of the Taiwan Strait occurs in the middle layer.The nutrient transport through the TS exhibits similar seasonal variations,as does the volume transport.The transport of nutrients from the Kuroshio accounts for more than 85% of the total.The transport of nutrients from the Taiwan Strait is greater during autumn and winter.The transport of dissolved inorganic nitrogen(DIN) from both rivers and atmospheric deposition through the TS peak in August.Nutrient transport cannot be equated with volume transport.The DIN in the less saline zone originates not only from rivers but also from atmospheric deposition and the Kuroshio.The transport of nutrients from the Taiwan Strait is not as significant as its volume transport in the TS.

Recent progress on nanomaterial-based electrochemical dissolved oxygen sensors

Dissolved oxygen(DO)usually refers to the amount of oxygen dissolved in water.In the environment,medicine,and fermentation industries,the DO level needs to be accurate and capable of online monitoring to guide the precise control of water quality,clinical treatment,and microbial metabolism.Compared with other analytical methods,the electrochemical strategy is superior in its fast response,low cost,high sensitivity,and portable device.However,an electrochemical DO sensor faces a trade-off between sensitivity and long-term stability,which strongly limits its practical applications.To solve this problem,various advanced nanomaterials have been proposed to promote detection performance owing to their excellent electrocatalysis,conductivity,and chemical stability.Therefore,in this review,we focus on the recent progress of advanced nanomaterial-based electrochemical DO sensors.Through the comparison of the working principles on the main analysis techniques toward DO,the advantages of the electrochemical method are discussed.Emphasis is placed on recently developed nanomaterials that exhibit special characteristics,including nanostructures and preparation routes,to benefit DO determination.Specifically,we also introduce some interesting research on the configuration design of the electrode and device,which is rarely introduced.Then,the different requirements of the electrochemical DO sensors in different application fields are included to provide brief guidance on the selection of appropriate nanomaterials.Finally,the main challenges are evaluated to propose future development prospects and detection strategies for nanomaterial-based electrochemical sensors.

Molecular investigation into the transformation of recalcitrant dissolved organic sulfur in refinery sour water during stripping process

Refinery sour water primarily originates from the tops of towers in various units and coker condensate,and cannot be discharged directly to a wastewater treatment plant due to high levels of chemical oxygen demand(COD)and organic sulfur contents.Even after the recovery of H_(2)S from the sour water by the stripping process,the effluent still contains a high concentration of dissolved organic sulfur(DOS),which can have a huge bad influence.While chemical composition of dissolved organic matter(DOM)in refinery wastewater has been extensively studied,the investigation of recalcitrant DOS from sour waters remains unclear.In the present study,chemical composition of sour water DOMs(especially DOS)was investigated using fluorescence spectroscopy(excitation-emission matrix,EEM)and mass spectrometry,including gas chromatography-mass spectrometry(GC-MS)and high-resolution Orbitrap MS.The GC-MS and EEM results showed that volatile and low-aromaticity compounds were effectively removed during the stripping process,while compounds with high hydrophilicity and humification degree were found to be more recalcitrant.The Orbitrap MS results showed that weak-polar oxygenated sulfur compounds were easier to be removed than oxygenated compounds.However,the effluent still contained significant amounts of sulfur-containing compounds with multiple sulfur atoms,particularly in the form of highly unsaturated and aromatic compounds.The Orbitrap MS/MS results of CHOS-containing compounds from the effluent indicate that the sulfur atoms may exist as sulfonates,disulfide bonds,thioethers.Understanding the composition and structure of sour water DOS is crucial for the development of effective treatment processes that can target polysulfide compounds and minimize their impact on the environment.

Temporal and Spatial Distribution of DIN and DIP Concentrations and Source Apportionment Along the Bohai Sea of China During 2015-2022

The Bohai Sea is one of the most polluted sea areas in China.In this study,we used 2184 integrated concentrations of dis-solved inorganic nitrogen(DIN)and dissolved inorganic phosphorus(DIP)in the Bohai Sea of China during spring(March,April,and May),summer(June,July,and August),and autumn(October and November)from 2015 to 2022 to explore the trends and sources of nutrients variations.From 2015 to 2022,DIN showed a downward trend until 2020 and then an upward trend,whereas DIP exhibited a stable trend with a slight decrease.The concentrations of DIN and DIP had similar seasonal pattern which was the highest in autumn(0.292±0.247 mg/L for DIN and 0.013±0.016 mg/L for DIP)but lower in spring(0.267±0.238 mg/L for DIN and 0.006±0.010 mg/L for DIP)and summer(0.263±0.324 mg/L for DIN and 0.008±0.010 mg/L for DIP).Sources of DIN and DIP apportioned by the positive matrix factorization(PMF)model were riverine input,sediment resuspension,sewage discharge,atmospheric deposition,and underground input.During 2015-2022,the largest contributor to DIN was sewage discharge(28.7%)and the largest contributor to DIP was sediment resuspension(44.6%).Seasonally,DIN in spring and autumn was dominated by sewage discharge(45.4%and 27.8%,re-spectively).Whereas in summer,it was dominated by riverine input(32.4%)and atmospheric deposition(29.7%).DIP was dominated by sediment resuspension during all three seasons(35.8%-52.5%).In addition,the increase in DIN concentrations in 2021 and 2022 were mainly due to the incremental input of river discharge and atmospheric deposition caused by increased precipitation during sum-mer and autumn.

Photochemical Production of Methyl Halides with Guaiacol as the Precursor

Methyl halides are crucial trace greenhouse gases in the atmosphere,playing a significant role in global climate change and the atmospheric environment.This study investigated the photochemical production of methyl halides in an artificial seawater system using guaiacol as a precursor through laboratory simulation experiments.The influences of various environmental factors,including illumination time,radiation wavebands,illumination intensity,concentrations of guaiacol and halide ions(X^(-)),Fe^(3+),salinity,dissolved oxygen(DO),and pH value on the photochemical production of methyl halides were examined.We demonstrated that increased illumination intensity and duration promote the photochemical production of methyl halides,with a notable enhancement under UV-B radiation.Guaiacol and halide ions were identified as key precursors,and their high concentrations facilitated the formation of methyl halides.Additionally,different types of halide ions exhibited a competitive relationship in producing methyl halides.The study found that an increase in pH inhibited the photochemical formation of CH_(3)I due to the reaction between OH^(-)and·CH_(3).Dissolved oxygen was found to inhibit the photochemical formation of CH3I while promoting the formation of CH_(3)Cl.Conversely,an appropriate concentration of Fe^(3+)enhanced the photochemical production of methyl halides.Field observations indicated a high photochemical production of methyl halides in the natural waters near Qingdao’s coastal area,likely due to the high concentration of dissolved organic matter(DOM),which supports photochemical reactions.Furthermore,the photochemical production of methyl halides in natural seawater was significantly higher than in dark conditions,underscoring the importance of illumination in promoting these photochemical processes in seawater.

Straw mulching alters the composition and loss of dissolved organic matter in farmland surface runoff by inhibiting the fragmentation of soil small macroaggregates

Straw mulching is a widespread practice for reducing the soil carbon loss caused by erosion.However,the effects of straw mulching on dissolved organic matter(DOM)runoff loss from black soil are not well studied.How straw mulching affects the composition and loss of runoff DOM by changing soil aggregates remains largely unclear.Here,a straw mulching treatment was compared to a no mulching treatment(as a control)on sloping farmland with black soil erosion in Northeast China.We divided the soil into large macroaggregates(>2 mm),small macroaggregates(0.25-2 mm),and microaggregates(<0.25 mm).After five rain events,the effects of straw mulching on the concentration(characterized by dissolved organic carbon(DoC)and composition(analyzed by fluorescence spectroscopy)of runoff and soil aggregate DOM were studied.The results showed that straw mulching reduced the runoff amount by 54.7%.Therefore,although straw mulching increased the average DOc concentration in runoff,it reduced the total runoff DOM loss by 48.3%.The composition of runoff DOM is similar to that of soil,as both contain humic-like acid and protein-like components.With straw mulching treatment,the protein-like components in small macroaggregates accumulated and the protein-like components in runoff declined with rain events.Fluorescence spectroscopy technology may help in understanding the hydrological paths of rain events by capturing the dynamic changes of runoff and soil DOM characteristics.A variation partitioning analysis(VPA)indicated that the DOM concentration and composition of microaggregates explained 68.2%of the change in runoff DOM from no mulching plots,while the change in runoff DOM from straw mulching plots was dominated by small macroaggregates at a rate of 55.1%.Taken together,our results demonstrated that straw mulching reduces the fragmentation of small macroaggregates and the loss of microaggregates,thus effecting DOM compositions in soil and reducing the DOM loss in runoff.These results provide a theoretical basis for reducing carbon loss in sloping farmland.

Inter-annual variations of dissolved oxygen and hypoxia off the northern Changjiang River(Yangtze River) Estuary in summer from 1997 to 2014

Hypoxia off the Changjiang River Estuary has been the subject of much attention,yet systematic observations have been lacking,resulting in a lack of knowledge regarding its long-term change and drivers.By revisiting the repeated surveys of dissolved oxygen(DO) and other relevant hydrographic parameters along the section from the Changjiang River Estuary to the Jeju-do in the summer from 1997 to 2014,rather different trends were revealed for the dual low-DO cores.The nearshore low-DO core,located close to the river mouth and relatively stable,shows that hypoxia has become more severe with the lowest DO descen ding at a rate of -0.07 mg/(L·a) and the thickness of low-DO zone rising at a rate of 0.43 m/a.The offshore core,centered around 40-m isobath but moving back and forth between 123.5°-125°E,shows large fluctuations in the minimum DO concentration,with the thickness of low-DO zone falling at a rate of -1.55 m/a.The probable factors affecting the minimum DO concentration in the two regions also vary.In the nearshore region,the decreasing minimum DO is driven by the increase in both stratification and primary productivity,with the enhanced extension of the Changjiang River Diluted Water(CDW) strengthening stratification.In the offshore region,the fluctuating trend of the minimum DO concentration indicates that both DO loss and DO supplement are distinct.The DO loss is primarily attributed to bottom apparent oxygen utilization caused by the organic matter decay and is also relevant to the advection of low-DO water from the nearshore region.The DO supplement is primarily due to weakened stratification.Our analysis also shows that the minimum DO concentration in the nearshore region was extremely low in 1998,2003,2007 and 2010,related to El Ni?o signal in these summers.

Rapid and real-time analysis of multi-component dissolved gas in seawater by Raman spectroscopy combined with continuous gas-liquid separator

Rapid and sensitive detection of dissolved gases in seawater is quite essential for the investigation of the global carbon cycle.Large quantities of in situ optical detection techniques showed restricted measurement efficiency,owing to the single gas sensor without the identification ability of multiple gases.In this work,a novel gas-liquid Raman detection method of monitoring the multi-component dissolved gases was proposed based on a continuous gas-liquid separator under a large difference of partial pressure.The limit of detection(LOD)of the gas Raman spectrometer could arrive at about 14 ml·L^(-1)for N_(2)gas.Moreover,based on the continuous gas-liquid separation process,the detection time of the dissolved gases could be largely decreased to about 200 s compared with that of the traditional detection method(30 min).Effect of equilibrium time on gas-liquid separation process indicated that the extracted efficiency and decay time of these dissolved gases was CO_(2)>O_(2)>N_(2).In addition,the analysis of the relationship between equilibrium time and flow speed indicated that the decay time decreased with the increase of the flow speed.The validation and application of the developed system presented its great potential for studying the components and spatiotemporal distribution of dissolved gases in seawater.

A numerical model study on the spatial and temporal variabilities of dissolved oxygen in Qinzhou Bay of the northern Beibu Gulf

Oxygen facilitates the breakdown of the organic material to provide energy for life.The concentration of dissolved oxygen(DO) in the water must exceed a certain threshold to support the normal metabolism of marine organisms.Located in the northern B eibu Gulf,Qinzhou B ay receives abundant freshwater and nutrients from several rivers which significantly influence the level of the dissolved oxygen.However,the spatial-temporal variations of DO as well as the associated driving mechanisms have been rarely studied through field observations.In this study,a three-dimension al coupled physical-biogeochemical model is used to investigate the spatial and seasonal variations of the DO and the associated driving mechanisms in Qinzhou B ay.The validation against observations indicates that the model can capture the seasonal and inter-annual variability of the DO concentration with the range of 5-10 mg/L.Sensitivity experiments show that the river discharges,winds and tides play crucial roles in the seasonal variability of the DO by changing the vertical mixing and stratification of the water column and the circulation pattern.In winter,the tide and wind forces have strong effects on the DO distribution by enhancing the vertical mixing,especially near the bay mouth.In summer,the river discharges play a dominant role in the DO distribution by inhibiting the vertical water exchange and delivering more nutrients to the Bay,which increases the DO depletion and results in lower DO on the bottom of the estuary salt wedge.These findings can contribute to the preservation and management of the coastal environment in the northern Beibu Gulf.

The Response of Carbonate System to Watershed Urbanization Process in a Semi-Arid River

Different from rivers in humid areas,the variability of riverine CO_(2) system in arid areas is heavily impacted by anthropogenic disturbance with the increasing urbanization and water withdrawals.In this study,the water chemistry and the controls of carbonate system in an urbanized river(the Fenhe River)on the semi-arid Loess Plateau were analyzed.The water chemistry of the river water showed that the high dissolved inorganic carbon(DIC)concentration(about 37 mg L^(-1))in the upstream with a karst land type was mainly sourced from carbonate weathering involved by H_(2)CO_(3) and H_(2)SO_(4),resulting in an oversaturated partial pressure of CO_(2)(pCO_(2))(about 800μatm).In comparison,damming resulted in the widespread appearance of non-free flowing river segments,and aquatic photosynthesis dominated the DIC and pCO_(2) spatiality demonstrated by the enriched stable isotope of DIC(δ^(13)CDIC).Especially in the mid-downstream flowing through major cities in warm and low-runoff August,some river segments even acted as an atmospheric CO_(2) sink.The noteworthy is wastewater input leading to a sudden increase in DIC(>55 mg L^(-1))and pCO_(2)(>4500μatm)in the downstream of Taiyuan City,and in cold November the increased DIC even extended to the outlet of the river.Our results highlight the effects of aquatic production induced by damming and urban sewage input on riverine CO_(2) system in semi-arid areas,and reducing sewage discharge may mitigate CO_(2) emission from the rivers.

Environmental dynamics of nitrogen and phosphorus release from river sediments of arid areas

Human activities lead to the accumulation of a large amount of nitrogen and phosphorus in sediments in rivers.Simultaneously,nitrogen and phosphorus can be affected by environment and re-enter the upper water body,causing secondary pollution of the river water.In this study,laboratory simulation experiments were conducted initially to investigate the release of nitrogen and phosphorus from river sediments in Urumqi City and the surrounding areas in Xinjiang Uygur Autonomous Region of China and determine the factors that influence their release.The results of this study showed significant short-term differences in nitrogen and phosphorus release characteristics from sediments at different sampling points.The proposed secondary kinetics model(i.e.,pseudo-second-order kinetics model)better fitted the release process of sediment nitrogen and phosphorus.The release of nitrogen and phosphorus from sediments is a complex process driven by multiple factors,therefore,we tested the influence of three factors(pH,temperature,and disturbance intensity)on the release of nitrogen and phosphorus from sediments in this study.The most amount of nitrate nitrogen(NO_(3)^(–)-N)was released under neutral conditions,while the most significant release of ammonia nitrogen(NH_(4)^(+)-N)occurred under acidic and alkaline conditions.The release of nitrite nitrogen(NO_(2)^(-)-N)was less affected by pH.The dissolved total phosphorus(DTP)released significantly in the alkaline water environment,while the release of dissolved organic phosphorus(DOP)was more significant in acidic water.The release amount of soluble reactive phosphorus(SRP)increased with an increase in pH.The sediments released nitrogen and phosphorus at higher temperatures,particularly NH_(4)^(+)-N,NO_(3)^(–)-N,and SRP.The highest amount of DOP was released at 15.0℃.An increase in disturbance intensity exacerbated the release of nitrogen and phosphorus from sediments.NH_(4)^(+)-N,DTP,and SRP levels increased linearly with the intensity of disturbance,while NO_(3)^(–)-N and NO_(2)^(–)-N were more stable.This study provides valuable information for protecting and restoring the water environment in arid areas and has significant practical reference value.

The impact of typhoons on the biogeochemistry of dissolved organic matter in eutrophic bays in northwestern South China Sea

Highly productive estuaries facilitate intense decomposition of dissolved organic matter(DOM) as a carbon source.However,the specific impacts of typhoons on DOM decomposition in eutrophic bays remain unclear.To address this issue,we investigated the spectral characteristics of DOM before and after Typhoon Ewiniar in Zhanjiang B ay,a eutrophic semi-enclosed bay in the northwestern South China Sea.The results revealed that intense microbial decomposition of DOM occurred during the pre-typhoon period because high nutrient inputs facilitated the mobilization of DOM in the bay.However,the intrusion of external seawater induced by the typhoon diluted the nutrient levels in Zhanjiang B ay,reducing the impact of microbial decomposition on DOM during the post-typhoon perio d.Nevertheless,the net addition of DOM occurred in Zhanjiang Bay during the post-typhoon period,possibly because of the decomposition of particulate organic matter(POM) and desorption of particulate matter.In addition,an increase in apparent oxygen utilization,a decrease in DO saturation and the reduced level of Chl a indicated that organic matter(OM) decomposition was enhanced and OM decomposition shifted to POM decomposition in Zhanjiang Bay after the typhoon.Overall,our study highlighted the shift in the intense OM decomposition from DOM to POM decomposition before and after typhoons in eutrophic bays,providing new insights into the response of typhoons to biogeo chemistry.

Exploration of the Existence Forms and Patterns of Dissolved Oxygen Molecules in Water

The structure of liquid water is primarily composed of three-dimensional networks of water clusters formed by hydrogen bonds,and dis-solved oxygen is one of the most important indicators for assessing water qual-ity.In this work,distilled water with different concentration of dissolved oxygen were prepared,and a clear negative correlation between the size of water clus-ters and dissolved oxygen concentration was observed.Besides,a phenomenon of rapid absorption and release of oxygen at the water interfaces was unveiled,suggesting that oxygen molecules predominantly exist at the interfaces of water clusters.Oxygen molecules can move rapidly through the interfaces among water clusters,allowing dissolved oxygen to quickly reach a saturation level at certain partial pressure of oxygen and temperature.Further exploration into the mechanism by molecular dynamics simulations of oxygen and water clusters found that oxygen molecules can only exist stably at the interfaces among water clusters.A semi-empirical formula relating the average number of water molecules in a cluster(n)to ^(17)O NMR half-peak width(W)was summarized:n=0.1 W+0.85.These findings provide a foundation for exploring the structure and properties of water.

Impacts of Water-Sediment Regulation Scheme on Chromophoric Dissolved Organic Matter in the Lower Yellow River

As a river with more than 3000 reservoirs in its watershed,the Yellow River has been affected by dams not only on the sediment load,but also on the water quality.Water-sediment regulation scheme(WSRS),which has been carried out annually in the Yellow River since 2002,is a typical human activity affecting river water quality.Chromophoric dissolved organic matter(CDOM)in river is susceptible to changes in ecological and environmental conditions as well as human activities.Here,we report variations in dissolved organic carbon concentrations,compositions and sources of CDOM in time series samples in the lower Yellow River during WSRS.In addition,a parallel factor fluorescence analysis(PARAFAC)method is applied to identify different fluorescent components in water samples during WRSR,showing four major components including tryptophan-like component(C1),microbial humic-like component(C2),terrestrial humic-like component(C3)and tyrosine-like component(C4).In general,C1 increased after water regulation,while C2 and C3 increased after sediment regulation,indicating that the water and sediment released by the dam have different effects on CDOM compositions.Under the impacts of the dam,source of CDOM in the lower Yellow River is mainly autochthonous related to microbial activities,and is regulated by the terrestrial input during WSRS period.Sediment resuspension inhibits microbial activities and reduces the production of autochthonous CDOM.Overall,human activities especially WSRS,as exemplified here,significantly alter the quality and quantity of CDOM in the lower Yellow River,affecting CDOM dynamics and biogeochemical processes in the estuarine environment.

Astragalus membranaceus(Fisch.)Bge.administered by dissolving microneedles achieves systemic therapeutic effects at low doses Author links open overlay panel

Objective:To determine the main components of Astragalus membranaceus(Fisch.)Bge(A.membranaceus,Huang Qi),Astragaloside IV(AIV)and Astragalus polysaccharides(AP),to characterize their properties,evaluate their in vivo efficacy,and to analyze drug diffusion using dissolving microneedle(DMN)technology in vivo.Methods: Respectively,AIV-and AP-loaded DMNs comprising chitosan(CTS)and polyvinyl alcohol(PVA)were prepared via dual-mold forming.Their morphology,mechanical properties,in vivo solubility,and skin irritation characteristics were tested.In vivo efficacy was assessed in cyclophosphamide-induced immunosuppressed mice,in vivo diffusion of AIV and AP by DMNs and conventional methods was compared,and the rheological properties of AIV-CTS-PVA and AP-CTS-PVA mixtures were measured.Results: Subcutaneous dissolution and absorption of AIV-CTS-PVA and AP-CTS-PVA microneedles(MNs)at low doses(50%–17%of intraperitoneal AIV injection and 12%–4%of intravenous AP injection)reduced the spleen index and acid phosphatase activity in immunosuppressed mouse models,increased the thymus index,and achieved equivalent or better systemic therapeutic effects.Compared with injections,AIV and AP achieved controllable solid-liquid conversion through delivery with CTS-PVA MNs,resulting in highly localized aggregation within 48 h,reducing the initial explosive effect of the drug,and achieving stable and slow drug release.Conclusion: The present study enhances our understanding of the efficacy and remote effects of drug-loaded DMNs from a traditional Chinese medicine(TCM)perspective,thereby promoting the development of precise and efficient delivery of TCM and further expanding the drug-loading range and application scenarios for DMNs.