Biological Immobilization Research Articles

Nitrogen addition reduces soil phosphorus leaching in a subtropical forest of eastern Tibetan Plateau

Globally, increased atmospheric nitrogen (N) deposition has comprehensively altered phosphorus (P) biogeochemical cycling in terrestrial ecosystems. Phosphorus is the second most common nutrient limiting for ecosystem productivity. Even though, ultimately under enhanced atmospheric N deposition it is likely to be the primary one. However, the response of soil P leaching to the elevated atmospheric N deposition in subalpine forests are still elusive. Here, we examined the effects of >7-year N additions on soil P leaching in a subalpine forest of eastern Tibetan Plateau. We found that independent of soil horizon (organic versus mineral horizons) and N addition rate (control 0, low 8 and high 40 kg N/ha yr−1), dissolved inorganic P (DIP), rather than dissolved organic P (DOP), dominated soil P leaching. The N addition treatments reduced the leaching of total P and DIP throughout the soil profile by 13 % and 14 %, respectively. The enhanced biological immobilization and P adsorption capacity (increased by 15–33 % in organic horizon and 9–35 % in mineral horizon) under the N addition contributed to the decrease in soil P leaching. We conclude that the reduction in soil P leaching under the elevated atmospheric N deposition should boost the enhanced N driven forest productivity and ecosystem carbon sequestration in the subalpine forests.

Functionalized maghemite superparamagnetic iron oxide nanoparticles (γ-Fe2O3-SPIONs)-amylase enzyme hybrid in biofuel production

The current study describes a straightforward, biologically and environmentally friendly method for creating magnetic iron oxide (γ-Fe2O3) nanoparticles. We report here that the Bacillus subtilis SE05 strain, isolated from offshore formation water near Zaafarana, the Red Sea, Hurghada, Egypt, can produce highly magnetic iron oxide nanoparticles of the maghemite type (γ-Fe2O3). To the best of our knowledge, the ability of this bacterium to reduce Fe2O3 has yet to be demonstrated. As a result, this study reports on the fabrication of enzyme-NPs and the biological immobilization of α-amylase on a solid support. The identified strain was deposited in GenBank with accession number MT422787. The bacterial cells used for the synthesis of magnetic nanoparticles produced about 15.2 g of dry weight, which is considered a high quantity compared to the previous studies. The XRD pattern revealed the crystalline cubic spinel structure of γ-Fe2O3. TEM micrographs showed the spherically shaped IONPs had an average size of 7.68 nm. Further, the importance of protein-SPION interaction and the successful synthesis of stabilized SPIONs in the amylase enzyme hybrid system are also mentioned. The system showed the applicability of these nanomaterials in biofuel production, which demonstrated significant production (54%) compared to the free amylase enzyme (22%). Thus, it is predicted that these nanoparticles can be used in energy fields.

Exploring the Role of 2D-Graphdiyne as a Charge Carrier Layer in Field-Effect Transistors for Non-Covalent Biological Immobilization against Human Diseases.

Graphdiyne's (GDY's) outstanding features have made it a novel 2D nanomaterial and a great candidate for electronic gadgets and optoelectronic devices, and it has opened new opportunities for the development of highly sensitive electronic and optical detection methods as well. Here, we testified a non-covalent grafting strategy in which GDY serves as a charge carrier layer and a bioaffinity substrate to immobilize biological receptors on GDY-based field-effect transistor (FET) devices. Firm non-covalent anchoring of biological molecules via pyrene groups and electrostatic interactions in addition to preserved electrical properties of GDY endows it with features of an ultrasensitive and stable detection mechanism. With emerging new forms and extending the subtypes of the already existing fatal diseases, genetic and biological knowledge demands more details. In this regard, we constructed simple yet efficient platforms using GDY-based FET devices in order to detect different kinds of biological molecules that threaten human health. The resulted data showed that the proposed non-covalent bioaffinity assays in GDY-based FET devices could be considered reliable strategies for novel label-free biosensing platforms, which still reach a high on/off ratio of over 104. The limits of detection of the FET devices to detect DNA strands, the CA19-9 antigen, microRNA-155, the CA15-3 antigen, and the COVID-19 antigen were 0.2 aM, 0.04 pU mL-1, 0.11 aM, 0.043 pU mL-1, and 0.003 fg mL-1, respectively, in the linear ranges of 1 aM to 1 pM, 1 pU mL-1 to 0.1 μU mL-1, 1 aM to 1 pM, 1 pU mL-1 to 10 μU mL-1, and 1 fg mL-1 to 10 ng mL-1, respectively. Finally, the extraordinary performance of these label-free FET biosensors with low detection limits, high sensitivity and selectivity, capable of being miniaturized, and implantability for in vivo analysis makes them a great candidate in disease diagnostics and point-of-care testing.

How sulfur species can accelerate the biological immobilization of the toxic selenium oxyanions and promote stable hexagonal Se0 formation

Toxic selenium oxyanions and sulfur species are often jointly present in contaminated waters and soils. This study investigated the effect on kinetics and resulting products for bio-reduction of selenium oxyanions in the presence of biologically produced sulfur resulting from bio-oxidation of sulfide in (bio)gas-desulfurization (bio-S0) and of sulfate. Selenite and selenate (~2 mmol L-1) bio-reduction was studied in batch up to 28 days at 30 oC and pH 7 using lactic acid and a sulfate-reducing sludge, 'Emmtec'. Bio-S0 addition increased the selenite removal rate, but initially slightly decreased selenate reduction rates. Selenite reacted with biologically generated sulfide resulting in selenium-sulfur, which upon further bio-reduction creates a sulfur bio-reduction cycle. Sulfate addition increased the bio-reduction rate for both selenite and sulfate. Bio-S0 or sulfate promoted hexagonal selenium formation, whereas without these, mostly amorphous Se0 resulted. With another inoculum, ‘Eerbeek’, bio-S0 accelerated the selenite reduction rate less than for ‘Emmtec’ because of lower sulfur and higher selenite bio-reduction rates. Bio-S0 addition increased the selenate reduction rate slightly and accelerated hexagonal selenium formation. Hexagonal selenium formation is advantageous because it facilitates separation and recovery and is less mobile and toxic than amorphous Se0. Insights into the interaction between selenium and sulfur bio-reduction are valuable for understanding environmental pathways and considerations regarding remediation and recovery.

Factors affecting ammonium capture by some Victorian lignites

ABSTRACT Nitrogen (N) loss from intensive animal husbandry leads to economic loss and environmental damage. Lignite has a demonstrated capacity to suppress ammonia (NH3) volatilisation from manure and this has been attributed to the pH, cation exchange capacity (CEC), pH buffer capacity and labile carbon (C) content of the lignite. Whilst lignite is effective in mitigating NH3 loss, the capacity for N retention and how this is influenced by the lignite's properties are not well studied. It is unclear if lignites from different mines will have comparable N retention under similar conditions. In this study, we characterised five Victorian lignites for their C-containing functional groups, surface morphology and chemical properties. These were then related to the ammonium () adsorption capacity of the lignites using a batch isotherm technique. The contribution of biological immobilisation to the N retention capacity of the lignites was determined using 15N tracing in an incubation study. All lignites were acidic (pHH2O: 3.3–5.8; pHCaCl2: 3.0–5.4). The lignite had similar patterns of distribution of C functional groups with the carboxyl C between 2.8% and 5.3%. The maximum adsorption capacity (Qmax ) varied with the composition of the lignite and correlated positively with the lignites’ CEC, pH and carboxyl groups. Increase in pH, especially from pH >5, resulted in up to 3-fold increase in Qmax (25.6 mg g−1), likely due to deprotonation of carboxyl groups. Compared to adsorption, the biological immobilisation of did not play a substantial role in the overall lignite's N retention capacity. Highlights Victorian lignites were assessed for their retention capacity using adsorption isotherms and 15N tracing. adsorption capacity of lignites increased (up to 3-fold) with pH, especially from pH 5 to 7. Biological immobilisation did not play a substantial role in the retention capacity of the lignites. pH-dependent adsorption was the dominant means by which lignite retained .

Mechanistic and analytical understanding of biological immobilization of chromium metal ions from waste-sites

In the proposed study, the isolation, identification and tolerance capacity of chromium (Cr(VI)) resistant fungi collected from different polluted sites of India has been studied. 12 fungal strains (FS1-FS12) have been isolated from the contaminated samples and cultured with different concentrations (100–500 ppm) of Cr(VI) to cumulate new biomasses. Screening and scrutinization divulges FS3 and FS5 isolates to be the most tolerant fungi against the higher concentrations of tested heavy metal with the deduction percentage and uptake of 72.5 ± 0.4%, 73.01 ± 0.12% and 4.30 ± 0.27, 4.39 ± 0.32 mg/g respectively. FS3 and FS5 were identified as Aspergillus flavus and Aspergillus fumigatus by grounding the data of internal transcribed spacer rDNA (ITS) region. The values of correlation coefficients (R2) calculated for A. flavus and A. fumigatus supports the Langmuir isotherm more than that of Freundlich isotherm, thus putting forward the multilayer adsorption of Cr(VI) ions by the mycelium of the fungal strains. Characterization techniques such as Fourier transform infrared spectroscopy (FTIR) and Scanning electron microscopy (SEM) has rendered the comparative analysis of biosorbent before and after the removal of Cr(VI) ions, thus substantiating the results of adsorption isotherms. The obtained results have supported the detoxifying potential of both the isolated fungi towards Cr(VI), thus promoting the use of safe biotechnology as one of the sustained recuperative measures.

Biochar fungal pellet based biological immobilization reactor efficiently removed nitrate and cadmium

To efficiently and simultaneously remove nitrate (NO3−-N) and Cd(II) from aqueous solution, a novel type of biochar fungal pellet (BFP) immobilized denitrification bacteria (Cupriavidus sp. H29) composite was used in a bioreactor. The removal performance of the bioreactor R1 for the initial concentration of 27.7 mg L−1 nitrate and 10.0 mg L−1 Cd(II) reached 98.1 and 93.9% respectively, and the inoculation of strain H29 in bioreactor R1 significantly enhanced the removal efficiency of contaminants. The 3D-EEM spectra analysis showed that the activity of microorganisms in the bioreactor was higher at a lower concentration of Cd(II). FTIR indicated the effect of functional groups in BFP in bioadsorption of Cd(II). In addition, high-throughput analysis of species composition of the microbial community in the bioreactors at different levels demonstrated that strain H29 played a significant part in the bioreactor. This research provided a perspective for simultaneous restoration of nitrate and heavy metals in wastewater, and also enriched the application of fungal pellet (FP) in reactors.

Exploring the Role of 2d-Graphdiyne as Charge Carrier Layer in Field Effect Transistors for Non-Covalent Biological Immobilization Against Human Diseases

Exploring the Role of 2d-Graphdiyne as Charge Carrier Layer in Field Effect Transistors for Non-Covalent Biological Immobilization Against Human Diseases

Modified lignite and black coal reduce ammonia volatilization from cattle manure

Modified lignite and black coal (BC) are potential amendments for animal bedding to abate ammonia (NH3) emissions due to their large adsorption capacities for ammoniacal nitrogen (N). However, the ability of modified lignite and BC in reducing NH3 volatilization from livestock manure and the underlying mechanisms remain unknown. The present study has investigated the effect of lignite, modified lignite, BC and modified BC on NH3 volatilization from cattle manure, biological immobilization of manure ammoniacal N and manure properties. Modified lignite and BC reduced the NH3 volatilization from manure by 44 and 36%, respectively, which were comparable with original lignite (43%). The biological immobilization of applied stable isotope labelled 15N in lignite, modified lignite, BC and modified BC amended manures was 15, 18, 11 and 16%, respectively, which were significantly higher than that in unamended manure (4%, P < 0.001). In addition, NH4+-N concentrations of lignite, modified lignite and modified BC amended manures (7.0–7.3 mg g−1) were significantly higher than that of the unamended and original BC amended manures (3.3 and 4.8 mg g−1, respectively, P < 0.001). However, the manure pH in all treatments remained alkaline (pH > 8.2). Our results highlight that the adsorption and immobilization of manure ammoniacal N induced by amendments are the key drivers in reducing NH3 loss from manure, outweighing the pH effect. The findings of this study provide new insights into the mechanisms of coal amendments reducing NH3 loss from animal manure and their potential applications in intensive livestock systems.

Screen-Printed Graphene/Carbon Electrodes on Paper Substrates as Impedance Sensors for Detection of Coronavirus in Nasopharyngeal Fluid Samples.

Severe acute respiratory syndrome (SARS-CoV-2), the causative agent of the global pandemic, which has resulted in more than one million deaths with tens of millions reported cases, requires a fast, accurate, and portable testing mechanism operable in the field environment. Electrochemical sensors, based on paper substrates with portable electrochemical devices, can prove an excellent alternative in mitigating the economic and public health effects of the disease. Herein, we present an impedance biosensor for the detection of the SARS-CoV-2 spike protein utilizing the IgG anti-SARS-CoV-2 spike antibody. This label-free platform utilizing screen-printed electrodes works on the principle of redox reaction impedance of a probe and can detect antigen spikes directly in nasopharyngeal fluid as well as virus samples collected in the universal transport medium (UTM). High conductivity graphene/carbon ink is used for this purpose so as to have a small background impedance that leads to a wider dynamic range of detection. Antibody immobilization onto the electrode surface was conducted through a chemical entity or a biological entity to see their effect; where a biological immobilization can enhance the antibody loading and thereby the sensitivity. In both cases, we were able to have a very low limit of quantification (i.e., 0.25 fg/mL), however, the linear range was 3 orders of magnitude wider for the biological entity-based immobilization. The specificity of the sensor was also tested against high concentrations of H1N1 flu antigens with no appreciable response. The most optimized sensors are used to identify negative and positive COVID-19 samples with great accuracy and precision.

Simultaneous removal of calcium, fluoride, nickel, and nitrate using microbial induced calcium precipitation in a biological immobilization reactor

In this research, an immobilized biofilm reactor was established for the simultaneous removal of calcium (Ca2+), fluoride (F-), nickel (Ni2+), and nitrate (NO3--N) by microbial induced calcium precipitation (MICP). The operating parameters of the reactor, hydraulic retention time (HRT: 4, 8, and 12 h), influent Ca2+ concentration (36.0, 108.0, and 180.0 mg L−1), and influent Ni2+ concentration (0.0, 3.0, and 6.0 mg L−1) were discussed. Under the HRT of 12 h, influent Ca2+ concentration of 180.0 mg L−1, and influent Ni2+ concentration of 3.0 mg L−1, the removal ratios of Ca2+, F-, Ni2+, and NO3--N reached 45.31%, 79.55%, 85.11%, and 55.29%, respectively, which was the reactor stable operation performance. The SEM revealed the morphology of calcium-precipitated bio-crystals. XPS showed the Ca2+ and Ni2+ precipitate components and XRD further revealed the formation of CaCO3, Ca5(PO4)3OH, and NiCO3 precipitation. Nitrogen (N2) was the main gas produced in the reactor. Fluorescence spectroscopy manifested that extracellular polymers played an important role in the organism nucleation. High-throughput sequencing exhibited that Acinetobacter sp. H12 was the dominant bacterial group. This study provided a new insight for simultaneous remediation of Ca2+, F-, Ni2+, and NO3--N in water bodies.

Mechanistic and Analytical Understanding of Biological Immobilization of Chromium Metal Ions from Waste-Sites

Mechanistic and Analytical Understanding of Biological Immobilization of Chromium Metal Ions from Waste-Sites

Effect of Cornstalk Biochar Immobilized Bacteria on Ammonia Reduction in Laying Hen Manure Composting.

NH3 emission has become one of the key factors for aerobic composting of animal manure. It has been reported that adding microbial agents during aerobic composting can reduce NH3 emissions. However, environmental factors have a considerable influence on the activity and stability of the microbial agent. Therefore, this study used cornstalk biochar as carriers to find out the better biological immobilization method to examine the mitigation ability and mechanism of NH3 production from laying hen manure composting. The results from different immobilized methods showed that NH3 was reduced by 12.43%, 5.53%, 14.57%, and 22.61% in the cornstalk biochar group, free load bacteria group, mixed load bacteria group, and separate load bacteria group, respectively. Under the simulated composting condition, NH3 production was 46.52, 38.14, 39.08, and 30.81 g in the treatment of the control, mixed bacteria, cornstalk biochar, and cornstalk biochar separate load immobilized mixed bacteria, respectively. The cornstalk biochar separate load immobilized mixed bacteria treatment significantly reduced NH3 emission compared with the other treatments (p < 0.05). Compared with the control, adding cornstalk biochar immobilized mixed bacteria significantly decreased the electrical conductivity, water-soluble carbon, total nitrogen loss, and concentration of ammonium nitrogen (p < 0.05), and significantly increased the seed germination rate, total number of microorganisms, and relative abundance of lactic acid bacteria throughout the composting process (p < 0.05). Therefore, the reason for the low NH3 emission might be due not only to the adsorption of the cornstalk biochar but also because of the role of complex bacteria, which increases the relative abundance of lactic acid bacteria and promotes the acid production of lactic acid bacteria to reduce NH3 emissions. This result revealed the potential of using biological immobilization technology to reduce NH3 emissions during laying hen manure composting.

Chemical and biological immobilization mechanisms of potentially toxic elements in biochar-amended soils

The application of biochars for the remediation of water and soils contaminated with potentially toxic elements (PTEs) has seen a recent growing interest. The mechanisms of chemical immobilization of PTEs with biochars in aqueous media have been well defined. However, immobilization mechanisms by which biochars interact with PTEs in soil matrix are more complex. The biological immobilization mechanisms and their interactions with PTEs in biochar-amended soils are not as well defined. This review presents an overview of factors governing interactions of biochars with PTEs as well as the synergistic effect of biochars and microorganisms in biological immobilization processes. The effectiveness of biochars in improvement of microbial immobilization of PTEs mainly depends on biochar properties, application rates, and soil environments such as organic matter content, clay type and content, pH and redox potential. Although some modified biochars appear to be better than the pristine biochars for immobilization of PTEs, their potential adverse impacts on soil microbial activity should be considered. This review highlights the most common analytical methods to discover molecular interaction mechanisms between biochar and PTEs and future research areas required for the understanding of biochar-PTE interactions in polluted soil systems.

Sediment phosphorus speciation and retention process affected by invasion time of Spartina alterniflora in a subtropical coastal wetland of China.

In coastal wetland ecosystems, most phosphorus (P) accumulates in the sediments and becomes a major pollutant causing eutrophication by recycling to the water column in estuary areas, especially exotic plant invasions will change the nutrient cycling. In this study, a large wetland invaded by exotic species Spartina alterniflora for over 15years was selected to study the sediment P fractionation and its retention for different plant invasion periods. The samples were collected from east to west in September and the sediment P was fractionated into total P (TP), inorganic P (IP), iron/aluminum-bound P (Fe/Al-P), calcium-bound P (Ca-P), and organic P (OP). Additionally, the effect of the invasion period on the wetland P fractionation based on space-time reciprocal principle was investigated. For different S. alterniflora invasion periods, the average TP concentration was 675.37mgkg-1 with a range of 160.33-1071mgkg-1. The IP concentration was in the range of 107.33-813.33mgkg-1 (accounting for 54.4-79.5% of TP), of which Fe/Al-P and Ca-P represented up to 99.4%. In addition, the P retention (RP) was within 41.67-329.67mgkg-1. We also found that TP, IP, Fe/Al-P, Ca-P, OP, and RP in sediments were negatively correlated with pH (p < 0.05), and were also significantly positively correlated (p < 0.01) with water content and electrical conductivity. There were positive correlations between the various forms of P in the sediments (p < 0.01). However, the most important finding was that invasion time of S. alterniflora had a direct effect on the P speciation and three stages were determined. In the first stage, S. alterniflora mainly consumed the OP of the sediment. In the second stage, S. alterniflora showed great vitality and biological immobilization led to the transforming of IP to OP. In the third stage, all P fractions greatly decreased to values even lower than for the bare beach which indicated that S. alterniflora growth had begun to degenerate. These three stages well explained the P seemingly contradictory increases and decreases apparent in previous studies and provide important information for understanding the effect of S. alterniflora invasion.

Development of hybrid processes for the removal of volatile organic compounds, plasticizer, and pharmaceutically active compound using sewage sludge, waste scrap tires, and wood chips as sorbents and microbial immobilization matrices.

This study evaluated the reutilization of waste materials (scrap tires, sewage sludge, and wood chips) to remove volatile organic compounds (VOCs) benzene/toluene/ethylbenzene/xylenes/trichloroethylene/cis-1,2-dichloroethylene (BTEX/TCE/cis-DCE), plasticizer di(2-ethylhexyl) phthalate (DEHP), and pharmaceutically active compound carbamazepine from artificially contaminated water. Different hybrid removal processes were developed: (1) 300mg/L BTEX + 20mg/L TCE + 10mg/L cis-DCE + tires + Pseudomonas sp.; (2) 250mg/L toluene + sewage sludge biochar + Pseudomonas sp.; (3) 100mg/L DEHP + tires + Acinetobacter sp.; and (4) 20mg/L carbamazepine + wood chips + Phanerochaete chrysosporium. For the hybrid process (1), the removal of xylenes, TCE, and cis-DCE was enhanced, resulted from the contribution of both physical adsorption and biological immobilization removal. The hybrid process (2) was also superior for the removal of DEHP and required a shorter time (2days) for the bioremoval. For the process (3), the biochar promoted the microbial immobilization on its surface and substantially enhanced/speed up the bioremoval of toluene. The fungal immobilization on wood chips in the hybrid process (4) also improved the carbamazepine removal considerably (removal efficiencies of 61.3 ± 0.6%) compared to the suspended system without wood chips (removal efficiencies of 34.4 ± 1.8%). These hybrid processes would not only be promising for the bioremediation of environmentally concerned contaminants but also reutilize waste materials as sorbents without any further treatment.

Synthesis and Optimization of Acrylic-N-Acryloxysuccinimide Copolymer Microspheres

A micro-sized poly( n -butyl acrylate-co- N -acryloxysuccinimide) [poly(nBA-co-NAS] copolymer bio-carrier matrix has been synthesized from n-butyl acrylate (nBA) and N -acryloxysuccinimide (NAS) monomers through a single step emulsion photo-polymerization protocol. Narrower size distribution of the copolymer microspheres having a size in the range of 0.31-1.04 µm was obtained using nBA-SDS composition ratio of 0.25:5.00 (mL : mg). The FTIR analysis result confirmed the presence of the useful succinimide functional groups on the poly(nBA-co-NAS), which rendered the copolymer microspheres a feasible alternative to other polymers for use as biological immobilization carrier for enzymes and DNA molecules in the fabrication of advanced biosensor devices. The low glass transition temperature ( T g ) of the as-synthesized copolymer microspheres signifies the soft and good adhesion properties of the matrix to be attached to the solid support to form the miniature solid-state biosensing devices.

豫西丘陵坡地弃耕农田植被演替对土壤碳、氮库的影响

PDF HTML阅读 XML下载 导出引用 引用提醒 豫西丘陵坡地弃耕农田植被演替对土壤碳、氮库的影响 DOI: 10.5846/stxb201709261739 作者: 作者单位: 河南科技大学,河南科技大学,河南科技大学,河南科技大学,河南科技大学 作者简介: 通讯作者: 中图分类号: 基金项目: NSFC-河南人才培养联合基金（U1304306）；中国科学院战略性先导科技专项（XDA05050402）；河南科技大学第六届研究生创新基金（CXJJ-2016-ZR12） Effects of vegetation succession on soil carbon and nitrogen storage in abandoned hilly farmlands of the Western Henan Region Author: Affiliation: Henan University of Science and Technology,,,, Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:在豫西丘陵坡地弃耕农田中，设置一个时间梯度为1，3，8，15，25 a的弃耕演替系列，调查其群落数量特征、物种组成、植被与土壤的碳、氮储量，分析群落的自然次生演替过程，并探讨土壤碳库与氮库对植物群落演替的响应机制。结果表明，弃耕农田群落演替缓慢，阶段性不明显，大致可划分为一、二年生草本→多年生草本+灌木两个阶段。定植物种的多样性变化与附近的原生植被有关。在25 a的演替进程中，草本植物始终占据优势，旱生植物数量约是中生植物的4倍，C3植物数量逐渐增多；群落α多样性指数呈先增大后减小趋势，Margalef丰富度指数、Pielou均匀度指数与Shannon-Wiener综合多样性指数最大值分别为1.53、0.95、2.18，表明弃耕农田的自然演替促使群落结构更加复杂并趋向稳定。群落植物的碳、氮储量随着生物量的增加而增加，在25 a时分别达到313.14 g/m2和11.69 g/m2。土壤碳储量与氮储量的变化相反，在演替后期（25 a）土壤碳储量增加到960.98 g/m2，而氮储量则降低至27.08 g/m2，表明豫西弃耕农田土壤具有"固碳放氮"的生态现象。RDA分析表明，群落盖度、密度和生物量是影响土壤碳、氮储量的主要因子。从群落的生态功能变化分析，按照弃耕演替时间推进，土壤碳储量逐渐增大，有利于生态系统碳固定；而土壤氮库的缩减则不利于群落的稳定，建议增加群落中豆科植物的丰富度，从而促进土壤氮素固定，缓解氮素流失。 Abstract:Understanding the vegetation, soil status, and their relationship on abandoned farmland plays an important role in the determination of future land use. In this study, five hilly farmlands abandoned for different periods of time (1, 3, 8, 15, and 25 years) were selected as a series of successive abandonments in the Western henan region to investigate the quantitative characteristics and species composition of the plant community and the carbon and nitrogen storage in vegetation and the soil, to analyze the natural secondary succession process of the plant community, and to discuss how the soil carbon and nitrogen pool responded to the plant community succession. The main results indicated that:The abandoned farmland communities that possessed a slow succession progress and generally included two indistinct succession stages, from annual or biennial herbs to perennial herbs and shrubs. The plant species diversity was closely related to the surrounding native vegetation. Over 25 years, herbs in the community always had an advantage status, the number of xerophytes was more than four times that of mesophytes, and the quantity of C3 plants increased gradually. The α diversity index first increased and then decreased, and the maximum values of the Margalef, Pielou and Shannon-Wiener indices were 1.53, 0.95, and 2.18, respectively. These data could provide proof that the community structure became more complex and stable after a natural succession process of 25 years. Both plant carbon storage and nitrogen storage increased as the community biomass constantly accumulated, reaching values of 313.14 g/m2 and 11.69 g/m2, respectively, at the 25-year succession stage. The soil carbon storage trend opposed that of soil nitrogen storage. In the climax stage (25 a), the soil carbon storage increased to 960.98 g/m2, whereas the soil nitrogen storage was reduced to 27.08 g/m2. Therefore, the changes in the soil property of the abandoned farmlands in the Western henan region resulted in the ecological phenomenon of "carbon fixation and nitrogen release". Redundancy analysis (RDA) showed that the community coverage, density and biomass were the main factors affecting soil carbon and nitrogen storage. The analysis of the ecological function changes of these communities showed that soil carbon storage gradually increased as the time since abandonment increased, which was beneficial to the carbon fixation of the ecosystem. However, the reduction in soil nitrogen storage in abandoned farmlands did not, contribute to the stability of the ecosystem. Thus, an increase the richness of leguminous plants in the community was suggested to promote biological immobilization of soil total nitrogen and alleviate soil nitrogen loss. 参考文献 相似文献 引证文献

ID:4006 Advanced Nanotechnologies for Cancer Research

In this lecture, I will discuss the recent developments in our group in the advanced optical imaging systems, nanocarriers and nanodevices for caner research. I will first discuss the development of various nanoparticles for sensing the pH value in cellular environment. By surface functionalization schemes, it is possible to control the location of nanoparticles in cells allowing us to track the local pH value around the nanoparticles inside cancer cells. As for in vivo study, we have utilized the multi-photon microscopy to investigate the disease models with the help of nanoparticles. I will discuss the enhanced permeability and retention (EPR) effect, which is a key feature of tumor blood vessels. In general, EPR-mediated passive targeting highly relies on the prolonged circulation time of nanocarriers. Particularly important two parameters, (1) nanocarrier size and (2) surface property are expected to play a key role on the pharmacokinetics and the biodistribution of the carrier material. Previously studies highlighted protein corona neutrality as an important design in the development of targeted nanomaterial delivery and demonstrated that a small difference in the surface heterogeneity could result in profoundly different interactions with cells and tissues. Therefore, the control and understanding of protein corona composition are critical for successful EPR-targeted nanomedicine. I will use mesoporous silica nanoparticles (MSN) nanoparticles as an example to illustrate the effect of size and the surface heterogeneity of MSN on their biological fate both in vitro and in vivo. I will also summarize our recent development of the circulating tumor cells (CTCs) isolation chips. CTCs are cancer cells that break away from a primary tumor or metastatic site, escape from immunosurveillance, and then circulate in the peripheral blood with the capability of forming distant metastases. The identification of CTCs in patient blood samples is technically challenging because of the extremely low concentration of CTCs among a large number of hematologic cells. To address this unmet need for rare cell isolation, we have developed substrates using the synergistic effect of nanomaterials and biological immobilization of CTC markers for enhancing CTC capture efficiency during a liquid biopsy procedure. In addition to the pursuit of high-cell-capture yield and specificity from human blood on chips, further vertical integration for the downstream characterization of CTCs is required for future CTC chips, such as liquid biopsy, for achieving a variety of clinical applications. In our approach, we have employed three-dimensional (3D) conducting polymer-based bioelectronic interfaces (BEIs) that can be integrated on electronic devices for rare circulating tumor cell (CTC) isolation, detection, and collection via an electrically triggered cell released from chips.

Influence of organic and inorganic amendments on the bioavailability of lead and micronutrient composition of Indian mustard (Brassica juncea (L.) Czern) in a lead-contaminated soil

Irrigation with untreated sewage water in periurban areas and other anthropogenic activities have resulted in accumulation of lead (Pb) in soils. To prevent its movement to deeper soil layers and groundwater aquifers, identification of some viable remedial measures is necessary for chemical and biological immobilization of Pb in soil. The objective of this study was to evaluate the impact of organic and inorganic amendments on Pb bioavailability, immobilization and on their effectiveness in enhancing micronutrients and growth of Indian mustard (Brassica juncea (L.) Czern). A loamy sand soil spiked with five levels of Pb varying from 0 to 400 mg kg−1 soil was used for the screen house study. Amendments used were lime (CaCO3), farm yard manure (FYM) and press mud (PM) applied at 2.5 and 5.0 % (w/w) and silt + clay applied at 20 and 40 % (w/w). Indian mustard was grown for 60 days with adequate application of nitrogen, phosphorus and potassium. All amendments reduced the extraction of Pb and the magnitude of reduction was highest with the addition of silt + clay. Addition of amendments increased plant dry matter yield as compared to unamended soil. All amendments significantly reduced Pb accumulation by Indian mustard and the magnitude of reduction increased with increasing the rate of amendment application. The addition of amendments also increased the concentration of micronutrients in Indian mustard as compared to unamended soils. The ameliorative efficiency of amendments in terms of reducing Pb content in plants followed the order silt + clay > lime > FYM > PM.