Influence of Sorbitan Monooleate on Morphology and Drug Release Behavior of Emulsion Electrospinning Polycaprolactone Nanofibers

Ultrafine polycaprolactone(PCL)fibers containing watersoluble drug tetracycline hydrochloride(Tet)were prepared by emulsion electrospinning.Sorbitan monooleate(Span80)was added as an essential additive to form stable water/oil emulsions and fabricate fibers with core-sheath structure.Different concentrations of Span80(0-40 g/L)were used to investigate the stability of emulsion and size of dispersed droplets.The scanning electron microscope(SEM)images indicated that the morphology of the fibers with Span80 were beaded-free with diameters of 200-400 nm,and Span80 enhanced the spinnability of electrospinning solution.The laser scanning confocal microscope(LSCM)images indicated that Tet was well encapsulated into the core region of the PCL fibers.The transmission electron microscope(TEM)image showed the formation of core-sheath structure.The loading efficiency(LE)and entrapment efficiency(EE)of Tet were calculated and release profiles in artificial saliva buffer solution(pH=6.8)were also analyzed.The results revealed that LE and EE of fibers with Span80decreased with the increase of its concentration.Fibers with coresheath structure had a longer effective release lifetime than without Span80.The increase of Span80 resulted in higher hydrophilicity of fibers and faster release rate of Tet.

Release behavior of copper and zinc from sandy soils

The concentrations and chemical forms of copper(Cu) and zinc(Zn) in surface soils directly influence the movement of Cu and Zn. In this study, thirteen sandy soil samples with a wide range of total Cu and Zn concentrations were collected for evaluating the relationships between Cu and Zn release and extraction time, ratio of soil to water, pH and electrolyte types. The results indicated that Cu released in batch extraction that represents long-term leaching was mainly from exchangeable, and carbonate bound Cu fractions, and Zn released in the batch extraction was mainly from its carbonate bound fraction. However, the Cu and Zn leached from the soils using the column leaching that represents short-term leaching were mainly from their exchangeable fractions. Soil column leaching at different pH values indicated that the amounts of leached Zn and Cu were greatly affected by pH. The Cu and Zn release experiments with varying extraction times and ratio of soil to water suggest that long-term water-logging in the soils after rain may increase contact time of the soils with water and the release of Cu and Zn to water from the soils, and total amounts of Cu or Zn released from the soils increase, but the Cu or Zn concentration in the surface runoff decrease with increasing rainfall intensity. The increased Ca concentration in soil solution increased stability of organic matter-mineral complexes and might decrease the dissolution of organic matter, and thus decreased the release of Cu-binding component of organic matter. However, high concentration of Na in the soil solution increased the dispersion of the organic matter-mineral complexes and increased dissolution of organic matter and the release of Cu from the soils.

Mercury release behaviors of Guizhou bituminous coal during co-pyrolysis: Influence of chlorella

Co-pyrolysis of coal and seaweed can not only effectively decrease the carbon footprint but also improve the quality and output of coal pyrolysis products,however,the influence of seaweed on thermal releasing behaviors of mercury during co-pyrolysis process are still unclear.In this work,the chlorella and Guizhou bituminous coal were mixed and used to reveal the mercury release behavior during co-pyrolysis by the temperature programmed pyrolysis experiments,thermogravimetric and differential thermogravimetric analysis(TG-DTG)and thermogravimetry-mass spectrometry(TG-MS)methods,offering a sufficient explanation on the control technology of mercury pollutants in co-pyrolysis.The results exhibited that a large amount of reducing gases such as CO,H_(2) and H_(2)O were generated in chlorella at the temperature range of 100-500℃,which was favorable for the transformation from oxidized mercury to elemental mercury,thus remarkably increased the release of elemental mercury in the raw coal sample.The mixed chlorella also significantly lowered the decomposition temperature range(from 400-600 to 300-400℃)of pyrite-bound mercury and decreased the decomposition temperatures of the pyrite-bound mercury species.Additionally,in the copyrolysis about 91.82%of mercury was released into the gas phase below 400℃ and was 13.77% higher than that of in individual pyrolysis of coal.

Effects of Shock Pressure on Transition Pressure in Zr

Measurements of free surface velocity profiles of high-purity Zr samples under shock-wave loading are performed to study the dynamic strength and phase transition parameters. The peak pressure of the compression waves is within the range from 9 to 14 GPa, and the Hugoniot elastic limit is 0.5 GPa. An anomalous structure of shock waves is observed due to the α - ω phase transition in Zr. Shock pressure has effects on transition pressure which increases with increasing compression strength, and the stronger shocks have a lower transit time.

Mechanisms of Pb(Ⅱ) coprecipitation with natrojarosite and its behavior during acid dissolution

Lead(Pb) coprecipitation with jarosite is common in natural and engineered environments,such as acid mine drainage(AMD) sites and hydrometallurgical industry. Despite the high relevance for environmental impact, few studies have examined the exact interaction of Pb with jarosite and the dissolution behavior of each phase. In the present work, we demonstrate that Pb mainly interacts with jarosite in four modes, namely incorporation, occlusion,physically mixing, and chemically mixing. For comparison, the four modes of Pb-bearing natrojarosite were synthesized and characterized separately. Batch dissolution experiments were undertaken on these synthetic Pb-bearing natrojarosites under pH_(2) to simulate the AMD environments. The introduction of Pb decreases the final Fe releasing efficiency of jarosite-type compounds from 18.18% to 3.45%-5.01%, showing a remarkable inhibition of their dissolution. For Pb releasing behavior, PbSO_(4) dissolves in preference to Pb-substituted natrojarosite, i.e.,(Na, Pb)-jarosite, which primarily results in the sharp increase of Pb releasing concentration(> 40 mg/L). PbSO_(4) occlusion by jarosite-type compounds can significantly reduce the release of Pb. The results of this study could provide useful information regarding Fe and Pb cycling in acidic natural and engineered environments.

Rapid control of black and odorous substances from heavilypolluted sediment by oxidation:Efficiency and effects

The control ofblack and odorous substances in sediments is of crucial importance to improve the urban ecological landscape and to restore water environments accordingly.In this study,chemical oxidation by the oxidants NaClO,H2O2,and KMnO4 was proposed to achieve rapid control of black and odorous substances in heavily-polluted sediments.Results indicate that NaClO and KMnO4 are effective at removing Fe(II)and acid volatile sulfides.The removal efficiencies of Fe(II)and AVS were determined to be 45.2%,94.1%,and 93.7%,89.5%after 24-h exposure to NaClO and KMnO4 at 0.2 mmol/g,respectively.Additionally,rapid oxidation might accelerate the release of pollutants from sediment.The release of organic matters and phosphorus with the maximum ratios of 22.1%and 51.2%was observed upon NaClO oxidation at 0.4 mmol/g.Moreover,the introduction of oxidants contributed to changes in the microbial community composition in sediment.After oxidation by NaClO and KMnO4 at 0.4 mmol/g,the Shannon index decreased from 6.72 to 5.19 and 4.95,whereas the OTU numbers decreased from 2904 to 1677 and 1553,respectively.Comparatively,H2O2 showed a lower effect on the removal of black and odorous substances,pollutant release,and changes in sediment microorganisms.This study illustrates the effects of oxidant addition on the characteristics of heavily polluted sediments and shows that chemical oxidants may be an option to achieve rapid control of black and odorous substances prior to remediation of water environments.