八分园,九重天

1初访第一次来到八分园,是春节前一个晴朗的下午,乘车沿着嘈杂拥挤的曹安公路从市区往西,刚出外环不远便到了嘉城社区。街角一丛浓密的树林,完全遮住了八分园的入口。绕过绿化,一面八分园的指示牌指向了一片竹林。＂这里只有八分地,我又信奉‘做人八分即可,不必满’,所以就叫‘八分园’＂,俞挺如是说。穿过竹影密布的弯曲小径,便是简朴的前院,里面只有一棵树,锐角的门房边缘正对院门中线。应当是无意的吧,我想。倒是条石铺砌的小径简洁而颇有古风,在灰石子铺地中随形绕过门房,带我们来到中心庭院。

Synthesis and Ionic Conduction of Cation-deficient Apatite La9.33-2x/3MxSi6O26 Doped with Mg, Ca, Sr

Apatite-type lanthanum silicate with special conduction mechanism via interstitial oxygen has attracted considerable interest in recent years. In this work, pure powder of La9.33 2x/3MxSi6O26 （M=Mg, Ca, Sr） is prepared by the sol-gel method with sintering at 1000℃. The powder is characterized by X-ray diffraction （XRD） and scanning electron micrograph （SEM）. The apatite can be obtained at relatively low temperature as compared to the conventional solid-state reaction method. The measurements of conductivity of a series of doped samples La9.33-2x/3MxSi6O26 （M=Ca, Mg, Sr） indicate that the type of dopant and the amount have a significant effect on the conductivity. The greatest decrease in conductivity is observed for Mg doping, following the Ca and the Sr doped apatites. The effect is ultimately attributed to the amount of oxygen interstitials, which is affected by the crystal lattice distortion arising from cation vacancies.

CFD simulation with enhancement factor of sulfur dioxide absorption in the spray scrubber

A model describing the absorption process of SO2 into limestone slurry with a spray scrubber is presented. Both the physical performance of the spray liquid in the scrubber and the involved chemical reactions are analyzed in the model. A con- tinuous concentration change of H+ was solved by iterative coupling using Matlab, and it was found that there was a remarkable influence on the concentration of the other elements in the process of SO2 absorption. The calculations show that the enhancement factor exponentially grows with an increasing value of pH and logarithmically decays with an increasing value of the driving force. To verify the accuracy of the model, experiments were also carried out, and the results suggest that the model, after combining the physical performance of the spray and the enhancement factor, can more precisely describe SO2 absorption in a spray scrubber. Furthermore, a commercial computational fluid dynamics (CFD) tool is used to perform several simulations which describe and clarify the effects of variables on SO2 absorption. The results of numerical simulation can provide a basis for further design and optimization of the scrubber.

Morphologies of hydroxyapatite nanoparticles adjusted by organic additives in hydrothermal synthesis

Properties of hydroxyapatite （HA, Ca10（PO4）6（OH）2）, including bioactivity, biocompatibility, solubility and adsorption could be tailored over wide ranges by the control of particle composition, particle size and morphology. In order to satisfy various applications, well-crystallized pure HA nanoparticles were synthesized at moderate temperatures by hydrotherrnal synthesis, and HA nanoparticles with different lengths were obtained by adding organic additives. X-ray diffractometry （XRD） and Fourier transform infrared （FTIR） spectrometry were used to characterize these nanoparticles, and the morphologies of the HA particles were observed by transmission electron microscopy （TEM）. The results demonstrate that shorter rod-like HA particles can be prepared by adding cetyltrimethylammonium bromide （CTAB）, as the additive of CTAB can block the HA crystal growth along with c-axis. And whisker HA particles are obtained by adding ethylenediamine tetraacetic acid （EDTA）, since EDTA may have effect on the dissolution-repreeipitation process of HA.

Room temperature gas sensor based on tube-like hydroxyapatite modified with gold nanoparticles

The main goal of this work is to explore the possibility of using Au-modified hydroxyapatite(HA) as a potential sensor material. Tube-like HA structure was fabricated with the aid of a Nafion N-117 cation exchange membrane and gold(Au) nanoparticles were added by a hydrothermal method. The morphology, structure and composition were characterized by scanning electron microscopy(SEM), transmission electron microscopy(TEM), X-ray diffraction(XRD), and X-ray photoelectron spectroscopy(XPS). The gas sensing properties were also investigated. Results show that Au nanoparticles are dispersed into the HA powder, which is tube-like, with rough inner and outer surfaces. Compared with pure HA, Au-modified HA exhibits improved sensing properties for NH_3. 5%(mass fraction) Au-modified HA shows the highest response with relatively short response/recovery time. The response is up to 79.2% when the corresponding sensor is exposed to 200×10^(-6) NH_3 at room temperature, and the response time and recovery time are 20 s and 25 s, respectively. For lower concentration, like 50×10^(-6), the response is still up to 70.8%. Good selectivity and repeatability are also observed. The sensing mechanism of high response and selectivity for NH_3 gas was also discussed. These results suggest that Au-HA composite is a promising material for NH_3 sensors operating at room temperature.

Structural insights of mechanically induced aluminum-doped hydroxyapatite nanoparticles by Rietveld refinement

Aluminum doped hydroxyapatite （HA：AI3 ＋） nanopowders were successfully prepared via a simple and efficient one-pot mechanochemical route. The effects of dopant loading on phase compositions and structural features were assessed by Rietveld analysis. The XRD-Rietveld refinement revealed the stabilization of HA in hexagonal structure for all the samples. The sharpness and intensity of the apatite-derived XRD peaks decreased as the dopant content increased to 10% due to the increase in lattice imperfections and mechanically induced amorphization. The incorpo- ration of A13 ＋ into the HA lattice decreased the unit cell parameters. From the FfiR measurements, the representing bands of apatite were identified in all cases. The mechanosynthesized nanopowders consisted of nanospheroids with an average size of 44 - 20 nm and therefore are promising for bone tissue regeneration.

Synthesis,characterization and biological activity in vitro of FeCrAl(f)/HA asymmetrical biological functionally gradient materials

FeCrAl(f)/HA biological functionally gradient materials(FGMs) were successfully fabricated by the hot pressing technique.Scanning electron microscope(SEM),energy dispersive spectrometer(EDS) and bending strength test machine were utilized to characterize the microstructure,component,mechanical properties and the formation of the Ca-deficient apatite on the surface of these materials.The results indicate that an asymmetrical FeCrAl(f)/HA FGM,consolidating powders prepared by mixing HA with 3%–15%(volume fraction) is successfully prepared.Both of the matrix and FeCrAl fiber are integrated very tightly and bite into each other very deeply.And counter diffusion takes place to some extent in two phase interfaces.The elemental compositions of the FeCrAl(f)/HA FGM change progressively.Ca and P contents increase gradually with immersion time increasing,and thereafter approach equilibrium.The bone-like apatite layer forms on the materials surface,which possesses benign bioactivity,and the favorable biocompatibility can provide potential firm fixation between FeCrAl(f)/HA asymmetrical FGM implants and human bone.

Reactive Crystallization of Calcium Sulfate Dihydrate from Acidic Wastewater and Lime

The present work focused on the recycle of the sulfate and the metal ions from acidic wastewater dis charged by nonferrous metallurgical industry. The effects of the temperature, the reactant concentration, the stirring speed and the metal ions on the reactive crystallization process of calcium sulfate between sulfuric acid and lime were systematically investigated. The morphology of the precipitated crystals evolved from plateletlike and nee dlelike shape to rodlike shape when the temperature was increased from 25 to 70 ℃. An increase in the agglom.

The Effect of Tree Species on the Chemical Properties of Soil in the Rehabilitation of a Limestone Quarry at Athi River, Kenya

A comparison of field performance of Acacia xanthophloea, Schinus molle, Casuarina equisetifolia and Gravellia robusta plant species was made in an exhausted limestone quarry, backfilled with limestone mine waste in a semi-arid area in Athi River, Kenya. The aim of the study was to determine if the tree species had an influence on the soil chemical properties. The soil had alkaline pH ranging from 8.0 to 8.98, low nitrogen content （〈 0.03%）, moderate phosphorus concentrations ranging from 44.15 ppm to 21.33 ppm and high to moderate exchangeable cations （Na, Ca, Mg and K）. All the tree species exerted a positive influence on soil properties necessary for plant growth. The pH values and total phosphorus were relatively lower in soils close to the trees （0.5 m） and increased with distance from the trees, while the soil values for total nitrogen and exchangeable cations were relatively higher close to the trees. C. equisetifolia had the best growth performance and a higher positive influence on the soil chemical properties necessary for plant growth followed by A. xanthophloea. It was concluded that trees should remain a feature of quarry rehabilitation because of their role in maintaining the biophysical environment.

Formation and in vitro induction ability of apatite nanobelt coating on silicon

Apatite coating with nanobelt structure was fabricated on single crystal silicon by a two-step method of electrodeposition at 1.0-2.0 mA/cm2 with DC power and vapor-thermal treatment(VTT) at 150-180℃ for 6 h over alkali medium.Scanning electron microscopy(SEM),X-ray diffractometry(XRD),and electron diffraction spectrometry(EDS) were employed to investigate the compositions and morphologies of specimens before or after vapor-thermal treatment.The results demonstrate that nanobelt crystals of coating,0.5-2 μm in width,100 nm in thickness,and 6-10 μm in length,are Ca-deficient apatite(CDA) with a mole ratio of Ca to P approximately of 1.60,which shows similarity of the nanobelt coating to inorganic phase in composition and to collagen in dimension appearing in human hard tissue.Induced nucleation and growth of bone-like apatite were observed on the nanobelt after soaking in a simulated body fluid(SBF) for 6 h and for 3 d,respectively,identifying that nanobelt has good ability for induction of bone-like apatite in SBF.

Polymeric nanocomposites loaded with fluoridated hydroxyapatite Ln^(3+)(Ln = Eu or Tb)/iron oxide for magnetic targeted cellular imaging

Objective： To fabricate polymeric nanocomposites with excellent photoluminescence, magnetic properties, and stability in aqueous solutions, in order to improve specificity and sensitivity of cellular imaging under a magnetic field. Methods： Fluoridated LnS＋-doped HAP （Ln3＋-HAP） NPs and iron oxides （lOs） can be encapsulated with biocompatible polymers via a modified solvent exaction/evaporation technique to prepare polymeric nanocomposites with fluoridated Ln3＋-HAP/iron oxide. The nanocomposites were characterized for surface morphology, fluorescence spectra, magnetic properties and in vitro cytotoxicity. Magnetic targeted cellular imaging of such nanocomposites was also evaluated with confocal laser scanning microscope using A549 cells with or without magnetic field. Results： The fabricated nanocomposites showed good stability and excellent luminescent properties, as well as low in vitro cytotoxicity, indicating that the nanocomposites are suitable for biological applications. Nanocomposites under magnetic field achieved much higher cellular uptake via an energy-dependent pathway than those without magnetic field. Conclusion： 1tie nanocomposites fabricated in this study will be a promising tool for magnetic targeted cellular imaging with improved specificity and enhanced selection.

火红的果

一水库的堤坝又加宽了,有十几米吧,黑色的柏油路面沿着河边弯弯曲曲的向南延伸出好远,然后钻进一片绿色的树林。

风水宝地燕来居

童话故事,旷野里的城堡,是邪恶的滋生地还是王子和公主幸福的摇篮?爱幻想的孩子力所能及地用毛高、茅草在荒地里支起一个窝棚,为自己营造一个天堂!著名的经济学家张五常先生忽发奇想,带着几分孩童的天真花巨资在乡村郊外建起一座宾馆,是一时兴起还是为找寻童年失落的梦?疑问中,水乡金湖已是春光初现,袅袅晨雾中一座独特的大房子在乡野间若隐若现。"乒乓乒乓"

Iron Mobilization and Mineralogical Alterations Induced by Iron-Deficient Cucumber Plants (Cucumis sativus L.) in a Calcareous Soil

Dicotyledons cope with ion(Fe) shortage by releasing low-molecular-weight organic compounds into the rhizosphere to mobilize Fe through reduction and complexation mechanisms. The effects induced by these root exudates on soil mineralogy and the connections between Fe mobilization and mineral weathering processes have not been completely clarified. In a batch experiment, we tested two different kinds of organic compounds commonly exuded by Fe-deficient plants, i.e., three organic acids(citrate, malate, and oxalate)and three flavonoids(rutin, quercetin, and genistein), alone or in combination, for their ability to mobilize Fe from a calcareous soil and modify its mineralogy. The effect of root exudates on soil mineralogy was assessed in vivo by cultivating Fe-deficient and Fe-sufficient cucumber plants(Cucumis sativus L.) in a RHIZOtest device. Mineralogical analyses were performed by X-ray powder diffraction. The batch experiment showed that citrate and, particularly, rutin(alone or combined with organic acids or genistein)promoted Fe mobilization from the soil. The combinations of rutin and organic acids modified the soil mineralogy by dissolving the amorphous fractions and promoting the formation of illite. These mineralogical alterations were significantly correlated with the amount of Fe mobilized from the soil. The RHIZOtest experiment revealed a drastic dissolution of amorphous components in the rhizosphere soil of Fe-deficient plants, possibly caused by the intense release of phenolics, amino acids, and organic acids, but without any formation of illite. Both batch and RHIZOtest experiments proved that exudates released by cucumber under Fe deficiency concurred to the rapid modification(on a day-scale) of the mineralogy of a calcareous soil.

Changes in Olsen P in Relation to P Balance in Contrasting Agricultural Soils

Maintaining soil phosphorus （P） at adequate levels for plant growth requires assessing how the long-term P balance （viz., the difference between P inputs and outputs） results in changes in soil test P. The hypothesis that routinely measured soil properties can help predict the conversion factor of P balance into Olsen P was tested at 39 sites in agricultural areas of the Mediterranean region in Spair~. A set of soil samples from each site was analyzed for Olsen P, inorganic P （P extracted using 0.5 mol L-1 H2SO4）, pseudototal P （P extracted using 0.5 mol L-1 H2SO4 following ignition at 550 ~C）, and organic P （the difference between pseudototal P and inorganic P）. Organic and Olsen P were uncorrelated in most of the 39 soil sets, which suggests that organic P content changed little with P inputs and outputs. The slopes of the regression lines of Olsen P against pseudototal and inorganic P, which were used as two different measures of the conversion factor, ranged widely （from 0.03 to 0.25 approximately）, with their average values （about 0.10） being similar to those found in long-term experiments conducted in temperate areas. Neither conversion factor was significantly correlated with any routinely measured soil property; however, the conversion factor for inorganic P was significantly lower for calcareous soils than for noncalcareous soils. Our negative results suggest the need to isolate the influence of soil properties from that of management systems and environmental factors relating to P dynamics in future studies.

Effects of Common Ions on Zn Sorption in Some Calcareous Soils of Western Iran

Zinc （Zn） is essential to plant growth and relatively mobile in soils. This study was conducted to assess the effect of common ions （Ca2＋, K＋, Na＋, NH＋, CI-, NO3-, and H2PO4） on sorption of Zn in surface samples of ten calcareous soils from western Iran using 10 mmol L-1 KC1, KNO3, KH2P04, Ca（N03）2, NAN03, and NH4N03 solutions as background electrolytes. The results indicated that both NH＋, K＋, and Ca2＋ equally decreased Zn sorption as compared to Na＋. Zinc sorption was decreased by H2PO4- as compared to NO3 and Cl-. The Langmuir and Freundlich equations fitted closely to the sorption data of all ions. The Langmuir maximum, bonding energy constant, and Freundlich distribution coefficient for Zn sorption differed among the various ionic background electrolytes. Langmuir sorption parameters showed that the presence of H2PO4- decreased the maximum Zn adsorbed, but increased the bonding energy. Although K＋ and NH＋ equally influenced maximum Zn adsorbed, they differed in their effect on the distribution coefficient of Zn in soils. Values of saturation index calculated using Visual MINTEQ indicated that at the low Zn concentration, Zn solubility was controlled by sorption reactions and at the high Zn concentration, it was mainly controlled by sorption and mineral precipitation reactions, such as precipitation of Zn3（PO4）2.4H2O, Zn5（OH）6（CO3）2, and ZnCO3. For most ionic background electrolytes, soil pH, CaC03, and cation exchange capacity （CEC） were significantly correlated with sorption parameters.