Cap Content Research Articles

Biphasic composite of calcium phosphate-based mesoporous silica as a novel bone drug delivery system

We reported the new biphasic composites of calcium phosphate and mesoporous silica material (CaP@MSi) in the form of powders and pellets as a potential bone drug delivery system for doxycycline hydrochloride (DOX). The CaP@MSi powders were synthesized by cationic surfactant-templating method. The effects of 10, 20, and 30% CaP content in the CaP@MSi powders on the molecular surface structure, the cytotoxicity against osteoblast cells in vitro, and the mineralization potential in simulated body fluid were investigated. The CaP@MSi characterized by the highest mineralization potential (30% CaP content) were used for DOX adsorption and pelletization process. The CaP which precipitated in the CaP@MSi composites was characterized as calcium-deficient with the Ca:P molar ratio between 1.0 and 1.2. The cytotoxicity assays demonstrated that the CaP content in MSi increases osteoblasts viability indicating the CaP@MSi (30% CaP content) as the most biocompatible. The combination of CaP and MSi was an effective strategy to improve the mineralization potential of parent material. Upon immersion in simulated body fluid, the CaP of composite converted into the bone-like apatite. The obtained pellets preserved the mineralization potential of CaP@MSi and provided the prolonged 5-day DOX release. The obtained biphasic CaP@MSi composites seem to have an application potential as bone-specific drug delivery system.

Differential response of biochar derived from rice-residue waste on phosphorus availability in soils with dissimilar pH

Although use of biochar as an amendment for soil C accretion has received immense prominence, its role on alleviating crop P demand remains largely contentious. Therefore, an incubation study for 60 days was conducted to examine the impact of biochar derived from rice-residue waste and Inorganic-P on phosphorous availability in soils with dissimilar pH (acid, neutral and alkali soil). The experimental soils were treated with 0, 20 g kg−1 (w/w) rice-residue biochar with three rates of Inorganic-P (KH2PO4) (0, 25, 50 mg kg−1). Application of rice-residue biochar alone or in combination with Inorganic-P in the experimental soils resulted in significant increase in P pools possibly due to greater available P content in biochar itself; biochar impelled decrease in soil P sorption capacity and or; biochar-facilitated release of soil organic matter bound P. Among the Inorganic-P fractions, content of Fe-P and Al-P was greater in acid soil, whereas Ca-P content was higher in neutral or alkali soils, irrespective of biochar and Inorganic-P treatments. Furthermore, ability of rice-residue biochar to decrease phospho-monoesterase activity in the experimental soils was indicative of its significance to act as a long-term source of phosphorous in soil. Therefore, amendment of soil with biochar can be used as an important strategy for sustainable management of surplus rice-residue and fulfilling phosphorous demand in differential pH soils of Indo-Gangetic plains.

Study on spatial-temporal distribution of different forms of phosphorus in wetland sediments

As an important factor for controlling phosphorus adsorption and release in wetland system, the forms of phosphorus in sediment has a decisive effect on phosphorus retention and release. Four different wetland systems were selected to study the phosphorus status and its environmental effects in wetland sediment. Phosphorus forms in sediments were related to aquatic plant characteristics. In the Vallisneria Linn. wetland system, the content of Ca-P of sediment was higher than the other systems because of its higher pH of the water. The maximum phosphorus adsorption capacity is 766.82-840.27 mg/kg. The content of Ca-P and TP have very good correlation with Smax. When the phosphorus concentration in the water is lower than 0.1mg/L, the surface sediment is no longer a “sink” of phosphorus but a “source” of phosphorus. The changes of TP in four wetland sediments basically follow a similar trend. The phosphorus content in the sediment decreased during the growth period of aquatic plants, and the wetland sediment as the phosphorus “source” provided the biomass for the growth of the aquatic plants. In autumn and winter, phosphorus in plants is released into wetland again with the decay of plants, resulting in the increase of phosphorus content in sediment.

Distribution and Release Characteristics of Phosphorus in a Reservoir in Southwest China

Dam construction changes the nutrient transport of a river system. Phosphorus is an important fundamental material in the global biochemical cycle and is always a limiting factor in the primary productivity of reservoirs. Extending the study of phosphorus in reservoirs is necessary given the dam construction in southwest China. Zipingpu Reservoir was chosen as the research site in this study. The form and distribution of phosphorus in the reservoir’s surface sediments and overlying water were analyzed. The results showed that overall, the total phosphorus (TP) content of surface sediments in the Zipingpu Reservoir decreased from the tail to the front of the dam. The TP content ranged from 682.39 to 1609.06 mg/kg, with an average value of 1121.08 mg/kg. The TP content at some sampling points was affected by exogenous input. Inorganic phosphorus (IP) was the main form of phosphorus in surface sediments and had a proportion of 89.38%. Among the forms of IP, the content of Ca-P was larger than that of O-P; Ex-P, Fe-P, and Al-P had the lowest contents. Particulate phosphorus (PP) was the main form of phosphorus in the overlying water of the Zipingpu Reservoir and was strongly affected by hydrodynamic conditions. The content of total dissolved phosphorus (TDP) in the overlying water was relatively low. To further understand the risk of phosphorus release in the surface sediments in the reservoir, the rate and flux of phosphorus exchange at the sediment-overlying water interface were investigated through laboratory experiments. The results showed that both water temperature and pH significantly affected the sediment release rate, but the influence of water temperature was more significant. Acidic and alkaline conditions were conducive to the release of phosphorus from sediment, while a neutral environment was not. The release rate significantly increased with increasing water temperature, and a positive linear relationship was found between these two parameters. The sediment exhibited absorption characteristics when the water temperature was extremely low and exhibited releasing characteristics at a high temperature. These results could provide a theoretical basis for the management and protection of reservoir water environments.

Phosphorus availability changes in acidic soils amended with biochar, fly ash, and lime determined by diffusive gradients in thin films (DGT) technique.

The lime, biochar, and fly ash are widely used to ameliorate acidic soils. The purpose of our pot experiment was to understand whether these soil amendments affected the availability of phosphorus in soils using diffusive gradients in thin films (DGT) technique. Three soil amendments, biochar (B), fly ash (F), and lime (L), were applied alone or combined to Ultisol and Alfisol at the rate of 40, 40, and 6g/kg, respectively. The DGT and chemical extraction techniques were used to quantify the soil available (phosphorus) P dynamic in the rice growth period. The addition of amendments can effectively increase the phosphorus content extracted by 0.01M KCl solution. The biochar amendment showed the best effect on increasing the contents of DGT-P and Olsen-P in the soil. Combined with the DGT-induced fluxes in sediments (DIFS) model, it was found that soil amendments mainly increased the adsorption rate (k) and desorption rate (k-1), and reduced soil reflect time (Tc) of phosphorus released to the pore water. The P contents accumulated in rice grains correlated more closely with the effective P concentration measured by DGT technique, compared with those with soil total P, pore water P, and Olsen-P. These results suggested that the DGT technique had significant advantage over conventional chemical extraction techniques when assessing the bioavailability of phosphorus to rice growth. Application of soil amendments increased the contents of Al-P and Ca-P of both Ultisol and Alfisol, and decreased the content of Fe-P in soils. The addition of amendments could change the affinity of Fe and phosphorus decreasing the phosphorus fixation in soils. The increase of available phosphorus in soil is mainly due to the change of pH value and the direct diffusion of phosphorus in the amendments (biochar and fly ash). In conclusion, soil amendment can affect the availability and adsorption ability of phosphorus in soil, and biochar has the best effect on the availability of soil phosphorus.

Biogenic selenium nanoparticles synthesized by Stenotrophomonas maltophilia SeITE02 loose antibacterial and antibiofilm efficacy as a result of the progressive alteration of their organic coating layer.

SummaryIncreasing emergence of drug‐resistant microorganisms poses a great concern to clinicians; thus, new active products are urgently required to treat a number of infectious disease cases. Different metallic and metalloid nanoparticles have so far been reported as possessing antimicrobial properties and proposed as a possible alternative therapy against resistant pathogenic microorganisms. In this study, selenium nanoparticles (SeNPs) synthesized by the environmental bacterial isolate Stenotrophomonas maltophilia SeITE02 were shown to exert a clear antimicrobial and antibiofilm activity against different pathogenic bacteria, either reference strains or clinical isolates. Antimicrobial and antibiofilm capacity seems to be strictly linked to the organic cap surrounding biogenic nanoparticles, although the actual role played by this coating layer in the biocidal action remains still undefined. Nevertheless, evidence has been gained that the progressive loss in protein and carbohydrate content of the organic cap determines a decrease in nanoparticle stability. This leads to an alteration of size and electrical properties of SeNPs along with a gradual attenuation of their antibacterial efficacy. Denaturation of the coating layer was proved even to have a negative effect on the antibiofilm activity of these nanoparticles. The pronounced antimicrobial efficacy of biogenic SeNPs compared to the denatured ones can – in first instance – be associated with their smaller dimensions. This study showed that the native organic coating layer of biogenic SeNPs functions in avoiding aggregation and maintaining electrostatic stability of the nanoparticles, thus allowing them to maintain efficient antimicrobial and antibiofilm capabilities.

Does biochar affect the availability and chemical fractionation of phosphate in soils?

Biochar as a soil amendment has been reported to affect the content and availability of soil nutrients. In this study, we aimed to test whether the biochar addition to soils would change the availability and chemical fractionation of phosphate in soils. Two soils (Ultisol and Alfisol) were amended with five kinds of biochars at application rate of 0, 1, and 2% (w/w). After 3-month incubation, availability and chemical forms of P were measured to investigate the potential effect and role of biochar in improving P availability in soils. The biochars used here had a lager variation of P content, depending on their feedstocks. Compared to the untreated soils, application of biochars derived from deciduous tree leaves (DLB), reed (RB), and rice straw (RSB) significantly increased the pH of two soils. The total P content of biochar-amended soils was increased with the addition of biochars. However, only RSB exhibited a significant increase (p < 0.05) of total P content. Application of biochars significantly increased the NH4Cl-extractable P content of two soils, indicating that biochars were able to increase the availability of phosphate in soils, but the amount of available P was dependent on biochar types. Ultisol and Alfisol amended with RSB (2% w/w) showed an increase in the P availability (0.5M NaHCO3-extractable P) by 46 and 39%, respectively. For strongly acidic Ultisol, addition of biochar significantly increased Al-P and Ca-P content, as well as decreased Fe-P content. The P desorption test indicated the release of P from soils increased with the addition of biochar. Results suggested that biochar would change the P sorption affinity of the soil and help to increase the availability of fixed P. The increase of P availability with biochar application was due to the pH change and direct P contribution from biochar. Our results concluded that biochar affected the availability, chemical forms, and sorption capability of phosphate in soil. The extent of biochar effects on soil P varied greatly with the type of feedstock of biochar and soil type.

Analysis of factors controlling sediment phosphorus flux potential of wetlands in Hulun Buir grassland by principal component and path analysis method.

Phosphorus (P) flux potential can predict the trend of phosphorus release from wetland sediments to water and provide scientific parameters for further monitoring and management for phosphorus flux from wetland sediments to overlying water. Many studies have focused on factors affecting sediment P flux potential in sediment-water interface, but rarely on the relationship among these factors. In the present study, experiment on sediment P flux potential in sediment-water interface was conducted in six wetlands in Hulun Buir grassland, China and the relationships among sediment P flux potential in sediment-water interface, sediment physical properties, and sediment chemical characteristics were examined. Principal component analysis and path analysis were used to discuss these data in correlation coefficient, direct, and indirect effects on sediment P flux potential in sediment-water interface. Results indicated that the major factors affecting sediment P flux potential in sediment-water interface were amount of organophosphate-degradation bacterium in sediment, Ca-P content, and total phosphorus concentrations. The factors of direct influence sediment P flux potential were sediment Ca-P content, Olsen-P content, SOC content, and sediment Al-P content. The indirect influence sediment P flux potential in sediment-water interface was sediment Olsen-P content, sediment SOC content, sediment Ca-P content, and sediment Al-P content. And the standard multiple regression describing the relationship between sediment P flux potential in sediment-water interface and its major effect factors was Y=5.849-1.025X 1-1.995X 2+0.188X 3-0.282X 4 (r=0.9298, p<0.01, n=96), where Y is sediment P flux potential in sediment-water interface, X 1 is sediment Ca-P content, X 2 is sediment Olsen-P content, X 3 is sediment SOC content, and X 4 is sediment Al-P content. Therefore, future research will focus on these sediment properties to analyze the interrelation among sediment properties factors, main vegetable factors, and environment factors which influence the sediment P flux potential in sediment-water interface.

Effect of fertilizers at various levels of recommended dosages with organic manures and seed inoculation on phosphorus fractions in postharvest soils

A field experiment was conducted at KVK, Srinagar during two consecutive Kharif of 2009-10 and 2010-11 to study the effect of fertilizers at various levels of recommended dosages with organic manures and microbial inoculation of seeds on the contents of different P fractions (Fe-P, Al-P and Ca-P) in postharvest soils under temperate conditions. The field experiment with soybean [Glycine max (L.) Merill] as the crop was laid out with 18 treatments viz. three levels of recommended dosages (RD) of inorganic fertilizers (50, 75 and 100% RD) along with organic manures (control, and FYM and Dalwood, both at 10 t ha-1) and biofertilizers by means of seed inoculation (control and dual inoculation with Rhizobium + PSB), in complete randomised block design. Each treatment was replicated thrice. The results revealed that the application of inorganic fertilizers, organic manures and bio-inoculation (INM) significantly increased the Fe-P, Al-P and Ca-P fractions in postharvest soils. With the application of fertilizers at 100 per cent level of RD along with the manures and seed inoculation, postharvest soil Fe-P, Al-P and Ca-P contents were higher than when the fertilizers were applied at 50 and 75 per cent level of RD. FYM proved to be superior to Dalweed towards increasing the levels of soil P fractions (Fe-P, Al-P and Ca-P). The levels various inorganic P-fractions increased also with dual inoculation of Rhizobium and PSB of the seeds.

New Off-On Sensor for Captopril Sensing Based on Photoluminescent MoO x Quantum Dots.

Molybdenum oxide nanomaterials have recently attracted widespread attention for their unique optical properties and catalytic performance. However, until now, there is little literature on the application of photoluminescent molybdenum oxide nanomaterials in biological and pharmaceutical sensing. Herein, photoluminescent molybdenum oxide quantum dots (MoOx QDs) were synthesized via a facile method, and then, the synthesized MoOx QDs were further applied as a new type of photoluminescent probe to design a new off–on sensor for captopril (Cap) determination on the basis of the fact that the quenched photoluminescence of MoOx QDs by Cu2+ was restored with Cap through specific interaction between the thiol group of Cap and Cu2+. Under optimal conditions, the restored photoluminescence intensity showed a good linear relationship with the content of Cap, ranging from 1.0 to 150.0 μM, with a limit of detection of 0.51 μM (3σ/k). Additionally, the content of Cap in pharmaceutical samples was successfully detected with the newly developed off–on sensor, and the recoveries were 99.4–101.7%, which suggest that the present off–on sensor has a high accuracy.

Effect of Montmorillonite on Fractions and Availability of Phosphorus in Soils Applied with Organic Fertilizer

An incubation experiment was carried out to study the effect of montmorillonite on pH, the fractions and availability of phosphorus in a sandy yellow soil (SY) and a mineral flavicant soil (MF) applied with biogas residues of swine manure (BSR). The rates of montmorillonite applied were 0%, 5%, 7.5% and 10%, respectively. The results indicated that soil pH was not affected by BSR, but was significantly increased by montmorillonite. In both soils, application of BSR caused an increase in the content and proportion of Al-P during the incubation, and an increase in the content but a slight decrease in the proportion of Fe-P in later period of incubation. The concentration of O-P was not markedly changed, but its proportion was decreased by applying BSR in both soils. The changes of Ca-P varied with soils. BSR had no significant influence on Ca-P content, but decreased the proportion of Ca-P in SY, meanwhile, it increased both Ca-P content and proportion in MF. Addition of montmorillonite in soils applied with BSR decreased the contents and proportions of Al-P and O-P, and the proportion of Fe-P did not change the contents of Fe-P, but increased the content and proportion of Ca-P in SY. In MF, montmorillonite could decrease the contents and proportions of Fe-P and O-P, and the proportion of Al-P did not affect the content of Al-P, but increased the contents and proportions of Ca-P greatly. The contents of available phosphorus (A-P) were enhanced by 17.9%-38.0% and 17.1%-33.7% in SY and MF respectively, and the phosphorus activation coefficient (PVC) was significantly improved in both soils by applying BSR. The contents of A-P were reduced by 8.8%-35.5% and 1.1%-11.6% in SY and MF respectively. Correlation analysis showed that montmorillonite reduced the availability of phosphorus through increasing pH and contents of Ca-P, decreasing the content of Al-P in SY, and through increasing pH and decreasing content of Fe-P in MF. The availability of phosphorus in SY was influenced more obviously than that in MF by montmorillonite.

Characteristics of soil aggregates and inorganic phosphorus fractions in soils returned from cropland to tea

With soils returned from cropland to tea planting for different ages (2-3, 9-10 and 16-17 years old) as the object, and the nearby cropland soil as the control in Zhongfeng Township, Mingshan County, Ya'an, Sichuan Province, field investigation and laboratory analysis were combined to investigate the characteristics of soil aggregates and inorganic phosphorus fractions in response to the returning from cropland to tea. The particle size of >2 mm was the dominant aggregate size for the cropland and tea soils. With the increasing age, soil aggregate content of >5 mm particle size increased, while that of <5 mm particle size decreased gradually. In the earlier ages, for the mean mass diameter (MWD) and the geometry mass diameter (GWD), there was no significant difference between the cropland and tea soils. The MWD and GMD for the tea soils of 9-10 years and 16-17 years increased with the increasing age and were higher than those of the control. Compared with the cropland, the tea soils showed higher contents of Al-P and Fe-P, and lower content of O-P. The content of O-P in different particle size of aggregates reduced with the increasing age, while that of Al-P and Fe-P increased with the increasing age. The contents of Al-P and Ca-P in the cropland and tea soils increased with the decrease of the particle size and reached the maximum value in the particle size of <0.25 mm. The highest content of Fe-P was observed in the particle size of <0.25 mm, followed by 2-5 mm and 0.25-0.5 mm. Besides, with the returning fromcropland to tea planting, O-P gradually accumulated in smaller particle size and possessed higher content in the particle size of <2 mm.

Intratumoral and Intertumoral Genomic Heterogeneity of Multifocal Localized Prostate Cancer Impacts Molecular Classifications and Genomic Prognosticators

BackgroundNext-generation sequencing is revealing genomic heterogeneity in localized prostate cancer (CaP). Incomplete sampling of CaP multiclonality has limited the implications for molecular subtyping, stratification, and systemic treatment. ObjectiveTo determine the impact of genomic and transcriptomic diversity within and among intraprostatic CaP foci on CaP molecular taxonomy, predictors of progression, and actionable therapeutic targets. Design, setting, and participantsFour consecutive patients with clinically localized National Comprehensive Cancer Network intermediate- or high-risk CaP who did not receive neoadjuvant therapy underwent radical prostatectomy at Roswell Park Cancer Institute in June–July 2014. Presurgical information on CaP content and a customized tissue procurement procedure were used to isolate nonmicroscopic and noncontiguous CaP foci in radical prostatectomy specimens. Three cores were obtained from the index lesion and one core from smaller lesions. RNA and DNA were extracted simultaneously from 26 cores with ≥90% CaP content and analyzed using whole-exome sequencing, single-nucleotide polymorphism arrays, and RNA sequencing. Outcome measurements and statistical analysisSomatic mutations, copy number alternations, gene expression, gene fusions, and phylogeny were defined. The impact of genomic alterations on CaP molecular classification, gene sets measured in Oncotype DX, Prolaris, and Decipher assays, and androgen receptor activity among CaP cores was determined. Results and limitationsThere was considerable variability in genomic alterations among CaP cores, and between RNA- and DNA-based platforms. Heterogeneity was found in molecular grouping of individual CaP foci and the activity of gene sets underlying the assays for risk stratification and androgen receptor activity, and was validated in independent genomic data sets. Determination of the implications for clinical decision-making requires follow-up studies. ConclusionsGenomic make-up varies widely among CaP foci, so care should be taken when making treatment decisions based on a single biopsy or index lesions. Patient summaryWe examined the molecular composition of individual cancers in a patient's prostate. We found a lot of genetic diversity among these cancers, and concluded that information from a single cancer biopsy is not sufficient to guide treatment decisions.

MafB and the role of macrophage apoptosis in atherosclerosis: A time to kill, a time to heal

MafB and the role of macrophage apoptosis in atherosclerosis: A time to kill, a time to heal

Development of dental composites with reactive fillers that promote precipitation of antibacterial-hydroxyapatite layers

The study aim was to develop light-curable, high strength dental composites that would release calcium phosphate and chlorhexidine (CHX) but additionally promote surface hydroxyapatite/CHX co-precipitation in simulated body fluid (SBF). 80 wt.% urethane dimethacrylate based liquid was mixed with glass fillers containing 10 wt.% CHX and 0, 10, 20 or 40 wt.% reactive mono- and tricalcium phosphate (CaP). Surface hydroxyapatite layer thickness/coverage from SEM images, Ca/Si ratio from EDX and hydroxyapatite Raman peak intensities were all proportional to both time in SBF and CaP wt.% in the filler. Hydroxyapatite was, however, difficult to detect by XRD until 4 weeks. XRD peak width and SEM images suggested this was due to the very small size (~10 nm) of the hydroxyapatite crystallites. Precipitate mass at 12 weeks was 22 wt.% of the sample CaP total mass irrespective of CaP wt.% and up to 7 wt.% of the specimen. Early diffusion controlled CHX release, assessed by UV spectrometry, was proportional to CaP and twice as fast in water compared with SBF. After 1 week, CHX continued to diffuse into water but in SBF, became entrapped within the precipitating hydroxyapatite layer. At 12 weeks CHX formed 5 to 15% of the HA layer with 10 to 40 wt.% CaP respectively. Despite linear decline of strength and modulus in 4 weeks from 160 to 101 MPa and 4 to 2.4 GPa, respectively, upon raising CaP content, all values were still within the range expected for commercial composites. The high strength, hydroxyapatite precipitation and surface antibacterial accumulation should reduce tooth restoration failure due to fracture, aid demineralised dentine repair and prevent subsurface carious disease respectively.

Genetic Evidence Supports a Major Role for Akt1 in VSMCs During Atherogenesis.

Coronary artery disease, the direct result of atherosclerosis, is the most common cause of death in Western societies. Vascular smooth muscle cell (VSMC) apoptosis occurs during the progression of atherosclerosis and in advanced lesions and promotes plaque necrosis, a common feature of high-risk/vulnerable atherosclerotic plaques. Akt1, a serine/threonine protein kinase, regulates several key endothelial cell and VSMC functions including cell growth, migration, survival, and vascular tone. Although global deficiency of Akt1 results in impaired angiogenesis and massive atherosclerosis, the specific contribution of VSMC Akt1 remains poorly characterized. To investigate the contribution of VSMC Akt1 during atherogenesis and in established atherosclerotic plaques. We generated 2 mouse models in which Akt1 expression can be suppressed specifically in VSCMs before (Apoe(-/-)Akt1(fl/fl)Sm22α(CRE)) and after (Apoe(-/-)Akt1(fl/fl)SM-MHC-CreER(T2E)) the formation of atherosclerotic plaques. This approach allows us to interrogate the role of Akt1 during the initial and late steps of atherogenesis. The absence of Akt1 in VSMCs during the progression of atherosclerosis results in larger atherosclerotic plaques characterized by bigger necrotic core areas, enhanced VSMC apoptosis, and reduced fibrous cap and collagen content. In contrast, VSMC Akt1 inhibition in established atherosclerotic plaques does not influence lesion size but markedly reduces the relative fibrous cap area in plaques and increases VSMC apoptosis. Akt1 expression in VSMCs influences early and late stages of atherosclerosis. The absence of Akt1 in VSMCs induces features of plaque vulnerability including fibrous cap thinning and extensive necrotic core areas. These observations suggest that interventions enhancing Akt1 expression specifically in VSMCs may lessen plaque progression.

不同退耕年限下菜子湖湿地土壤磷素组分特征变化

PDF HTML阅读 XML下载 导出引用 引用提醒 不同退耕年限下菜子湖湿地土壤磷素组分特征变化 DOI: 10.5846/stxb201312082909 作者: 作者单位: 安徽师范大学 国土资源与旅游学院,安徽师范大学,南京牛首山园林管理有限公司,安徽师范大学 国土资源与旅游学院,安徽师范大学 国土资源与旅游学院,安徽师范大学 国土资源与旅游学院 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金项目（41001369；41301249）；安徽省自然科学基金资助（1308085MD22） Characteristics of soil phosphorus fractions in wetlands with various restoration age in caizi lake, Anhui Province Author: Affiliation: College of Territorial Resource and Tourism,Anhui Normal University/ Anhui key Laboratory of Natural Disasters Process and Prevention,College of Territorial Resource and Tourism,Anhui Normal University/ Anhui key Laboratory of Natural Disasters Process and Prevention,,College of Territorial Resource and Tourism,Anhui Normal University/ Anhui key Laboratory of Natural Disasters Process and Prevention,College of Territorial Resource and Tourism,Anhui Normal University/ Anhui key Laboratory of Natural Disasters Process and Prevention,College of Territorial Resource and Tourism,Anhui Normal University/ Anhui key Laboratory of Natural Disasters Process and Prevention 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:选取菜子湖区不同退耕年限（2、5、8、10a和20a）湿地为研究对象，以仍耕作油菜地和原始湿地为参照，分析了土壤全磷（TP）、有效磷（AP）、有机磷（OP）和无机磷（IP）各形态含量，探讨退耕还湖后湿地土壤磷素组分特征变化规律。结果表明：研究区土壤无机磷各形态含量大小顺序为：铁磷（Fe-P：73.55-391.76 mg/kg）>钙磷（Ca-P：21.64-108.04 mg/kg）>闭蓄态磷（O-P：17.15-29.57 mg/kg）>铝磷（Al-P：5.84-25.97 mg/kg），其中Fe-P占了土壤无机磷总量的54.20%-74.13%；退耕还湖2-8a期间，湿地土壤Al-P、Fe-P和O-P含量有逐渐降低趋势，而退耕8-20a后逐渐上升，以Fe-P为主的这3形态磷左右着退耕后土壤无机磷的变化；Ca-P随退耕年限增加整体呈上升趋势，对土壤无机磷的贡献逐渐增加；无机磷占土壤全磷的比例为35.90%-67.27%，主导着退耕后湿地土壤全磷变化；有机磷占土壤全磷的17.82%-50.51%，在退耕2a后下降，随后开始逐渐上升，对退耕后湿地土壤磷库恢复的贡献逐渐增加；其中Fe-P、O-P和Al-P控制着退耕后土壤磷素有效性变化。退耕后水文条件、植被生长和土壤黏粒含量变化不仅影响退耕后湿地土壤磷素组分特征，也影响着退耕后湿地土壤磷素有效性。 Abstract:Phosphorus (P) is often the critical limiting nutrient controlling the productivity of wetlands. However, water eutrophication caused by P over enrichment impairs water quality and destroys wetland ecosystem. Very limited information is available on the characteristics change of P pool in wetland soils after returning farmland to lake (RFL). We used P fractionation techniques to investigate P distribution in soils, sampled from wetlands with various age (2, 5, 8, 10 and 20a) of RFL, rape field, and native wetlands in the Caizi lake, Anhui province. The results showed that the contents of inorganic P (IP) were in the order: Fe-P (73.55-391.76 mg/kg) > Ca-P (21.64-108.04 mg/kg) > O-P (17.15-29.57 mg/kg) > Al-P (5.84-25.97 mg/kg), moreover Fe-P, as a main component, accounted for 54.20%-74.13% of IP in studied field. All of Al-P, Fe-P and O-P declined within the restoration period of 2-8a, and began to increase gradually after 8a of RFL. The contents of Ca-P increased progressively with the age of RFL, and showed more and more contribution to IP. Soil inorganic P accounted for 35.90%-67.27% of soil total P, owning the same change tendency as Fe-P with various age of RFL, and dominated the change tendency of TP after RFL. Soil organic P accounted for 17.82%-50.51% of total P and increased gradually with the RFL age. With restoration age, the contribution of Ca-P to inorganic P pool and organic P to total P pool increased. The results also indicated Al-P, Fe-P and O-P controlled P availability in wetlands with RFL age. The changes of soil P contents, composition, and availability were attributed to soil clay content, and shift of hydrological condition and recovery status of vegetation after RFL. 参考文献 相似文献 引证文献

Can Statins Alter Coronary Plaque Morphology Assessed by Intravascular Ultrasound?

We read with interest the article by Hikita et al entitled ‘‘Impact of Statin Use Before the Onset of Acute Myocardial Infarction on Coronary Plaque Morphology of the Culprit Lesion.’’ They evaluated the impact of statin treatment before the onset of acute myocardial infarction (AMI) on coronary plaque morphology at culprit lesions by using intravascular ultrasound virtual histology (IVUS-VH) before percutaneous coronary intervention (PCI). They concluded that statin use before the onset of AMI might have effects on coronary plaque morphology of the AMI culprit lesion with less necrotic core and greater fibrous and fibrofatty component. Statin therapy, especially intensive doses, is associated with a decreased plaque size, lipid content, and thickness of the fibrous cap. Statins have pleiotropic effects that are independent of lipid-lowering effects. The pleiotropic effects of statins (anti-inflammatory and antithrombotic properties) are often greater with high doses of statins, and there may be individual differences among various statins. A study comparing 8 months of pitavastatin (4 mg daily) with pravastatin (20 mg daily) showed that pitavastatin induced a reduction in fibrous and fibrofatty tissue, but an increase in necrotic core while on pravastatin showed no effects on fibrous tissue and the necrotic core but a decrease in fibrofatty tissue. In the Hikita et al study, the statin doses are low and there is no information about the patients’ medication other than statins and whether there was statin loading before PCI. It would be useful if the authors provided information about the treatment duration of statins. Hikita et al evaluated the impact of statin treatment on coronary plaque morphology only at culprit lesions; it would be useful if they also evaluated nonculprit lesions. A 3-vessel gray-scale IVUS study showed that at least 1 plaque rupture was found somewhere other than at the culprit lesions in 79% of the patients with AMI. The results of the Providing Regional Observation to Study Predictors of Events in Coronary Tree (PROSPECT) trial provided data about the natural history of vulnerable plaques observed by gray-scale IVUS and IVUSVH. In this study, 697 patients with acute coronary syndrome underwent 3-vessel coronary angiography and IVUS study after PCI. At follow-up, recurrent clinical events were equally attributable to the culprit and nonculprit lesions. There have also been some concerns raised about the IVUS-VH because of its poor correlation with necrotic core in a porcine model. Although our goal must be the identification of vulnerable plaques before they rupture, assessment of ruptured plaques provides information regarding plaque vulnerability. Therefore, caution must be taken when drawing conclusions from studies using different IVUS approaches.

The Distribution Characteristics of Soil TP and IP Forms at the Xiangxi River Riparian Zone in the Three Gorges Reservoir

The soil samples along the Xiangxi River bank in the Three Gorges Reservoir were collected at exposed period. The total phosphorus and inorganic phosphorus contents in soil were determined, and their distribution characteristics were analyzed. The results show that the average content of TP is 1.0735gkg-1 (145-175m) and 1.225gkg-1 (175-185m) respectively. The downstream and upstream has the maximum and minimum values respectively. Ca-P and O-P are the major IP forms of Xiangxi River riparian zone. The midstream and upstream (145-175m) has the maximum and minimum content of Al-P and Fe-P respectively, while the downstream (175-185m) has maximum content of Al-P and Fe-P respectively. The downstream (145-185m) has minimum content, while the upstream and midstream has the maximum content of WS-P and O-P respectively. The upstream and downstream (145-185m) has the maximum and minimum content of Ca-P respectively. The bio-available phosphorus content decreased gradually and bio-unavailable phosphorus content increased gradually from downstream to upstream.

Gelation and biocompatibility of injectable alginate–calcium phosphate gels for bone regeneration

An emerging approach toward development of injectable, self-setting, and fully biodegradable bone substitutes involves the combination of injectable hydrogel matrices with a dispersed phase consisting of nanosized calcium phosphate particles. Here, novel injectable composites for bone regeneration have been developed based on the combination of ultrapure alginate as the matrix phase, crystalline CaP [monetite and poorly crystalline hydroxyapatite (HA)] powders as both a dispersed mineral phase and a source of calcium for cross-linking alginate, glucono-delta-lactone (GDL) as acidifier and glycerol as both plasticizer and temporary sequestrant. The composites were maximized with respect to CaP content to obtain the highest amount of osteoconductive filler. The viscoelastic and physicochemical properties of the precursor compounds and composites were analyzed using rheometry, elemental analysis (for calcium release and uptake), acidity [by measuring pH in simulated body fluid (SBF)], general biocompatibility (subcutaneous implantation in rabbits), and osteocompatibility (implantation in femoral condyle bone defect of rabbits). The gelation of the resulting composites could be controlled from seconds to tens of minutes by varying the solubility of the CaP phase (HA vs. monetite) or amount of GDL. All composites mineralized extensively in SBF for up to 11 days. In vivo, the composites also disintegrated upon implantation in subcutaneous or bone tissue, leaving behind less degradable but osteoconductive CaP particles. Although the composites need to be optimized with respect to the available amount of calcium for cross-linking of alginate, the beneficial bone response as observed in the in vivo studies render these gels promising for minimally invasive applications as bone-filling material.