Antibacterial Properties of Cerium-Bearing Stainless Steel Bearing Cerium

Antibacterial Properties of Cerium-Bearing Stainless Steel Bearing Cerium     

Structure and antibacterial activity of Ce3+ exchanged montmorillonites

Four kinds of Ce3+ exchanged montmorillonites(Ce/MMTs) were prepared by an ion-exchange reaction, and characterized with energy dispersive X-ray analysis (EDX), X-ray difference (XRD), X-ray photoelectron spectroscopy (XPS) and scanning electron micros-copy (SEM). The surface properties and antibacterial activity of Ce/MMTs were also investigated. The chemical compositions of Ce/MMTs were determined, and the cerium of Ce/MMTs was confirmed to be present as trivalent cerium state. The d001 basal spacings of Ce/MMTs were enlarged with the enhancement of the cerium contents, and the particles were formed with irregular shape. On increasing the Ce con-tents of Ce/MMTs, the special surface areas were decreased, but the total pore volumes and the average pore sizes were increased. The anti-bacterial activity of Ce/MMTs is increased with increasing the cerium contents, and 1.5g/L of Ce/MMT-3 containing 11.46wt.% of curium could remove all the Staphylococcus aureus and more than 99.9% of the Escherichia coli within 24.0 h of contact. Moreover, Ce/MMTs dis-played bactericidal activity.     

Learning and teaching styles: implications for teachers of family medicine

Glycine-conjugated, dihydroxy bile salts inhibit calcium hydroxyapatite (HAP) formation by binding to and poisoning nascent crystal embryos. Their taurine-conjugated counterparts bind less well to hydroxyapatite and do not inhibit its formation; but more hydrophobic, synthetic analogs of the taurine conjugated bile salts are inhibitors of hydroxyapatite formation. Because hydrophobicity is an important determinant of the ability of bile salts to inhibit hydroxyapatite crystal growth, experiments were performed to study the effect of the physiologically important mixed micelles of bile salt and phospholipid. Taurodeoxycholate/phosphatidylcholine (10:1) mixed micelles bound to HAP at lower total lipid concentrations than did pure taurodeoxycholate. At low total lipid concentrations, phosphatidylcholine (PC) binding appeared to predominate, suggesting that PC had a higher affinity than did taurodeoxycholate (TDC) for the HAP surface. Although glycodeoxycholate (3 mM) significantly (> 95%) inhibited hydroxyapatite precipitation, higher concentrations of taurodeoxycholate, either alone or mixed with phosphatidylcholine, did not affect hydroxyapatite formation. These results suggest that biliary phospholipids do not modulate the ability of bile salts to inhibit hydroxyapatite crystal growth.     

Synthesis, characterization and antimicrobial activity of zinc and cerium co-doped a-zirconium phosphate

A series of zinc ions or/and cerium ions co-doped α-zirconium phosphate (Zn-Ce@ZrPs) were prepared. The novel Zn-Ce@ZrPs were characterized and the antibacterial activity on Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus were tested. The results showed that zinc ions (Zn2+) or/and cerium ions (Ce3+) were combined with ZrP, and the Ce3+ was adsorbed on the surface of ZrP through hydrogen bonds, while Zn2+ intercalated into the interlayer of ZrP. Zn-Ce@ZrPs showed excellent synergistic antibacterial activity. When Zn2+/Ce3+ atomic ratio was 0.6, the Zn-Ce@ZrP3 showed the highest synergistic antibacterial efficiency, suggesting great potential application as antibacterial agents in microbial control.     

多层级NaHoF4纳米核壳颗粒的制备及其抗癌诊疗

为能够在无Ce掺杂时增强NaHoF4的荧光发射能力,设计制备了Yb3+浓度梯度多层级纳米核壳颗粒,并对其微观形貌、荧光发射能力、相结构及抗癌诊疗效果进行了测试。结果表明,合成的六边形NaHoF4颗粒结晶度良好,尺寸约为20 nm;多层级包覆壳层薄且均匀,该结构的荧光发射强度高于无/单一壳层包覆。980 nm激光照射下,表面修饰Ce6的多层级NaHoF4纳米核壳颗粒在HeLa癌细胞中具有良好的抗癌诊疗作用。     

The nucleation and growth of calcium phosphate crystals at protein and phosphatidylserine liposome surfaces

The kinetics of calcium phosphate crystal growth at the surfaces of proteins and phospholipids has been investigated using free drift and constant composition methods in supersaturated calcium phosphate solutions (relative supersaturations: with respect to hydroxyapatite, HAP, sigma HAP = 15.0, and with respect to octacalcium phosphate, OCP, sigma OCP = 1.9). Fibrinogen and collagen molecules adsorbed at hydrophobic surfaces as well as uncross-linked collagen fibrils induce ion binding and subsequent nucleation of calcium phosphate. The formation of OCP on phosphatidylserine vesicles introduced to highly supersaturated calcium phosphate solutions probably involves the interaction of the calcium ions with the ionized carboxylic groups of the phospholipid.     

Phosphates precipitating from artificial urine and fine structure of phosphate renal calculi

Phosphates precipitating from artificial urine in the pH range 6-8 were identified using X-ray diffraction, chemical analysis and scanning electron microscopy. The influence of magnesium and citrate on phases precipitating from urine was established. From urine containing a normal quantity of magnesium (around 70 ppm), brushite accompanied by hydroxyapatite (HAP) precipitated at pH < or = 7.0 and struvite with HAP at pH > 7.0. HAP was formed exclusively from magnesium deficient urine at pH 7.0. Newberyite, octacalcium phosphate and whitlockite were not identified. The chemical and phase composition and inner fine structure of 14 phosphate calculi were studied. Three types of stones were distinguished based on their magnesium content: (i) stones rich in magnesium composed of struvite, hydroxyapatite and abundant organic matter, (ii) stones with low magnesium content constituted by calcium deficient hydroxyapatite, up to 5% of struvite, considerable amount of organic matter and occasionally brushite, and (iii) calculi without magnesium consisting of brushite, hydroxyapatite and little organic matter. Conditions prevaling during stone-formation assessed for each type of stone were confirmed by corresponding urinary biochemical data and corroborate the in vitro studies of phosphates precipitation.     

Sorption of Pb2+, Cd2+, and Sr2+ Ions on Calcium Hydroxyapatite Powder Obtained by the Hydrothermal Method

The sorption of Pb2+, Cd2+, and Sr2+ ions from aqueous solutions by carbonate-substituted calcium hydroxyapatite (HAP) obtained by the hydrothermal decomposition of urea and calcium–ethylenediaminetetraacetic acid chelates was investigated. The shift of the point of zero charge (pHpzc) of HAP toward lower pH values in solutions of Pb2+ and Cd2+ ions, which was more pronounced for Pb2+ ions than for Cd2+ ions, indicates that specific adsorption of these cations on HAP had occurred. There was no shift of the pHpzc in the solution containing Sr2+ ions, suggesting that specific adsorption of this cation on HAP had not occurred. The sorption isotherms suggest that the sequence of the efficiency of sorption by HAP is Pb2+>Cd2+>Sr2+. Ion exchange is the main mechanism of removal of Sr2+ ions from aqueous solution by apatite, whereas during the sorption of Cd2+ ions, this mechanism occurs simultaneously with the process of specific adsorption. The interaction of the apatite with Pb2+ ions includes the previously mentioned mechanisms and dissolution of the apatite, followed by the precipitation of lead hydroxyapatite.     

Enhanced orange emission by doping CeB6 in CaAlSiN3:Ce3+ phosphor for application in white LEDs

A series of CeB6-doped and CeO_2-doped Ca_(1-x)SiAlN_3:xCe3+(denoted as CASN:Ce3+@CeB6 and CASN:Ce3+@CeO_2, respectively) were synthesized by alloy-nitridation method under high-purity nitrogen atmosphere. The morphologies, crystal phases, and luminescence properties were investigated in detail.With an increase in the concentration of CeB_6, the unit cell volume of CASN:Ce3+@CeB_6 slightly increases due to the substitution between ions, which leads to a change of micro structure around Ce3+. CASN:Ce3+@CeB6 efficiently emits yellow-orange light with a maximum emission intensity at around 550 nm for the content x of 0.01(being in comparable situation, CASN:Ce3+@CeO_2 is x = 0.04) when excited at460 nm. Compared with CASN:Ce3+@CeO_2, the red emission component of Ce3+ in CASN:Ce3+@CeB6 is much stronger. This is ascribed to energy transfer of intra-Ce3+(within one Ce3+ ion) and inter-Ce3+(between Ce3+ and Ce3+ ions). In addition, the replacements of N3-(0.132 nm for CN = 4) and O~(2-)(0.124 nm for CN = 4) by B~(2-)(0.140 nm for CN = 4), which can lead to a marked expansion of the host lattice and a decrease of the oxidation of samples, are also responsible for the increase of red emission component. Furthermore, CASN:Ce3+@CeB_6 phosphor has an excellent thermal stability because of the partial substitution of Ce-O(Ce-N) bonds by more covalent Ce-B. As a result, the outstanding luminescent properties of CASN:Ce3+@CeB6 phosphor make it practical to use in the single phosphor-coated high-color-rendering power white LED.     

A New Family of Ce6MoO15 as Fast Oxide Ion Conductor

A novel solid solution Ce6MoO15 was achieved. Their structure and oxide ionic conductivity were studied.Based on Ce6MoO15, rare earth element substitution on cerium site shows that all resulting oxides enhance the conductivity further, and have high oxide-ion conductivity, which may be a kind of promising material for SOFCs.     

Nanomechanics of Surface Modified Nanohydroxyapatite Particulates Used in Biomaterials

Hydroxyapatite is an important constituent of natural bone, and possesses excellent biocompatibility and bioactivity, but its brittle nature limits its use for bone tissue engineering. Nanohydroxyapatite (nanoHAP) has been used in synthesis of biomimetic composites for more than a decade, yet the mechanics of nanoHAP particles is not fully understood. The present work attempts to advance the current understanding of mechanics of hydroxyapatite at nanoscale, by carrying out systematic nanoindentation experiments on nanoHAP and surface modified nanoHAP [prepared by in situ mineralization in presence of polyacrylic acid (PAAc)]. Quantitative nanomodulus maps of both modified and unmodified HAP nanoparticles indicate that various surface features of HAP nanoparticles can be probed. Dips in values of elastic moduli across the nanoparticle surfaces in modified nanohydroxyapatite are indicative of composite responses from both polymer and mineral phases (PAAc-HAP) on the surface. Nanoindentation experiments were performed at 100, 1,000, 3,000, 5,000, and 8,000?μN loads, respectively, to obtain the indentation response from both shallow and deep penetration depths. Nanoindentation results at shallow penetration depths are influenced by nanoscale surface roughness of irregular-shaped HAP nanoparticles and nonuniform distribution of PAAc in the microstructure. Significant nonbonded interactions between HAP and PAAc, as well as the mechanical properties of individual constituents (HAP and PAAc) lead to superior nanomechanical properties of surface-modified nanoHAP as compared to unmodified HAP. The overall inelastic nanomechanical response (including damage leading to reduced overall elastic modulus) is strongly influenced by the nature of the interfaces between the nanoparticles, especially when indent size is much larger than the particle size.     

Investigation on the mechanism of adsorption and desorption behavior in cerium ions modified Y-type zeolite and improved hydrocarbons conversion

Different types of Y zeolites(HY, USY and Na Y) containing various amounts of cerium(Ce) were prepared with the method of liquid ion exchange and characterized by X-ray diffraction(XRD), intelligent gravimetric analyzer(IGA), and a molecular simulation technology(grand canonical Monte Carlo simulation, GCMC). A novel calculation method of desorption index(DI) was proposed and the influence of cerium cationic species on the processes of adsorption-desorption of hydrocarbon molecules(n-octane) on the cerium modified Y zeolites(Ce Y) was studied. The results indicated that Ce ion species played a key role in reducing desorption activation energy of n-octane on Y type zeolites, leading to an improvement of the desorption ability of the Ce Y and the regulation of the adsorption state of n-octane from aggregation to decentralization. These findings are essential factors for enhancing the product selectivity of light hydrocarbon component and the catalytic activity of rare earth modified Y zeolites(REY) catalysts in fluid catalytic cracking(FCC) process.     

Interaction of human gallbladder mucin with calcium hydroxyapatite: binding studies and the effect on hydroxyapatite formation

Calcium hydroxyapatite (HAP) crystals formed in vitro in the presence of polymeric human gallbladder mucin (1.0 mg/mL) were smaller (0.75 +/- 0.39 microns) than control crystals (7.86 +/- 2.76 microns), but the mucin did not affect the kinetics of crystal formation or alter the amount of mineral phase present at equilibrium. In contrast, glycopeptide subunits produced by proteolysis of the native mucin had no effect on HAP crystal size. Both native mucin and glycopeptides bound to mature HAP crystals, but the glycopeptides were much more readily displaced by phosphate ions. Therefore, in experiments where HAP was being formed, the phosphate ions inhibited the interaction of glycopeptides with the nascent HAP. These results indicate that gallbladder mucin may modulate HAP formation in vivo, and that this ability may be altered during pathological states, such as neutrophil infiltration or bacterial colonization, that may cause the release of proteinases capable of digesting mucin.     

La-Hexaaluminate Catalyst Preparation and Its Performance for Methane Catalytic Combustion

The La-hexaaluminate catalysts with high performance ration method with the buffer solution of NH4HCO3 and NH4OH were synthesized by the modified controllable co-precipimixture as the precipitation agent. The physicochemical properties of catalysts were characterized by the means of BET, XRD, and TPR techniques. With methane catalytic combustion as the probe reaction, the catalytic performances were also tested on a fixed bed, continual flow system. The resuits show that it is a good method to obtain chemical homogeneous hexaaluminate materials by the buffer solution as the precipitation agent. The La-hexaaluminate can be formed at low temperatures ranging from 1050 to 1200 ℃. The cerium introduction plays a great role in the methane catalytic combustion on La-Mn hexaaluminate because of its high oxygen storage capacity property and the well synergic effect between Ce and Mn. However, the CeO2 appears in hexaaluminate through the XRD pattern, which reveals that Ce can not enter the crystal lattice position. Mn introduction improves the methane catalytic activity to a large extent due to its high redox property. When Mn atomic substitution amount for A1 is 2, the hexaaluminate shows the highest activity, and the catalyst possesses good H2 consumption and redox performance. Mn can easily occupy the hexaaluminate crystal position, which reveals that the Mn substitute La-hexaaluminate is a promising high temperature methane combustion catalyst with high activity and good stability.     

稀土元素Ce对HSn62-1黄铜组织和脱锌腐蚀性能的影响

研究了加入稀土元素Ce对Hsn62-1黄铜组织的影响,利用腐蚀试验和电化学试验研究了稀土元素Ce的加入对合金耐脱锌腐蚀性能的影响。研究表明,加入稀土元素Ce明显地细化了合金的组织,使粗大的α、β板条状组织变成短小的细板条状组织。加入稀土元素Ce可以明显改善黄铜耐脱锌腐蚀性能。     

Influence of cerium on solidification,recrystallization and strengthening of Cu-Ag alloys

Cu-Ag-RE alloys with different Ce contents were prepared by vacuum melting, and microstructure evolution and mechanical properties of Cu-Ag-Ce alloys were investigated by optical microscopy, scanning electronic microscopy with electron back-scattered diffraction and tensile test. The results indicated that a columnar to equiaxed transition in cast Cu-Ag-RE alloys was observed due to Ce addition and area of the region with equiaxed grains enlarged with increasing Ce content. Cold-rolled Cu-Ag-RE alloys in annealed condition exhibited a partially or fully recrystallized grain structure depending on the concentration of Ce. The average grain size decreased and texture components changed with increasing Ce content. The main brass-type texture component changed to be copper-type as the Ce content increased from 0.05 wt.% to 1.0 wt.%. The Cu-Ag-RE alloy with 0.2 wt.% Ce showed maximum ultimate tensile strength, while the sample with 1.0 wt.% Ce showed a better comprehensive mechanical property.     

Effect of Rare Earths on Plants under Supplementary Ultraviolet-B Radiation: Ⅱ. Effect of Cerium on Antioxidant Defense System in Rape Seedlings under Supplementary Ultraviolet-B Radiation

Effects of cerium (Ce3 ) on membranous protective enzymes in rape seedlings exposed to two levels of enhanced ultraviolet-B radiation (UV-B, 280 ～ 320 nm) were studied by hydroponics in the laboratory. The results show that the chlorophyll content decreases and membrane permeability increases in the leaves under UV-B irradiation with an intenposed to a low level of UV-B radiation. POD activity in leaves exposed to a high level of UV-B radiation is enhanced constantly. The sensitivities of these enzymes to UV-B radiation are SOD ＞ CAT ＞ POD. The injury by UV-B radiation on the functions of protective enzymes is lightened, their ability to scavenge radicals is improved, and the membrane permeability is maintained by Ce. Furthermore, the protective effect of cerium is more obvious in plants exposed to low levels of UV-B radiation than to high levels of it. Accordingly, all results prove that the protective effect of Ce on plants under UV-B radiation is realized through the protective system of plants.     

二氧化硅负载的硫酸高铈固体酸催化剂上的缩合反应

通过溶胶-凝胶法和浸渍法制备了二氧化硅负载的硫酸高铈[Ce( SO4 )2/SiO2]固体酸催化剂,研究了乙酰乙酸乙酯和1,3 -丁二醇的缩合反应,考察了催化剂的焙烧温度、硫酸高铈的负载量、催化剂的浓度、原料摩尔比、反应时间对反应的影响.结果表明,与四水硫酸高铈相比,二氧化硅负载的硫酸高铈[ Ce( SO4 )2/SiO2]固体酸催化剂在乙酰乙酸乙酯和1,3 -丁二醇的缩合反应中具有较高的催化活性和良好的稳定性.最佳条件为:焙烧温度为500℃、乙酰乙酸乙酯和1,3 -丁二醇摩尔比为1∶1.2、硫酸高铈的负载量为15.0％、催化剂占乙酰乙酸乙酯的质量分数为7.5％、回流反应时间120 min,此时苹果酯的收率可达95.5％.     

RE-Carbide in High Carbon Steel

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Synthesis, Characterization and Antibacterial Properties of Rare Earth (Ce3+, Pr3+, Nd3+, Sm3+, Er3+)Complexes with L-Aspartic Acid and o-Phenanthroline

Five novel ternary complexes of rare earth ions with L-Aspartic acid (Asp) and o-phenanthroline (Phen) were synthesized in ethanol aqueous solution. Their compositions were characterized by elemental analysis, molar conductance, FT-IR, Raman, UV-VIS and TG-DTA. The compositions of the complexes were confirmed to be: RE(Asp)3PhenCl3·3H2O (RE: Ce3 , Pr3 , Nd3 , Sm3 , Er3 ). The antibacterial activity test shows that all these complexes exhibit excellent antibacterial ability against Escherichia coli, Staphylococcus aureus and Candida albicans. The antimicrobial spectrum of the complexes are broad.