Surface changes of yttria‐stabilized zirconia in water and Hanks solution characterized using XPS

Adhesion of soft and hard tissues to yttria‐stabilized zirconia (YSZ) has been reported, despite its chemical inertness. To investigate the underlying mechanism of adhesion of hard and soft tissues to YSZ in dental implants, YSZ disks with (100), (110), and (111) crystalline planes were immersed in water for 60 days and in Hanks solution for 7 days, and the changes in the surface chemical states were characterized using X‐ray photoelectron spectroscopy. After immersion in water for 60 days, the concentration of hydroxyl groups on the YSZ surface increased. Therefore, the surface of YSZ was hydrated during immersion in water. In addition, phosphate groups were formed on the surface of YSZ immersed in Hanks solution. We conclude that the formation of phosphate on the YSZ surface in physiological conditions can promote reaction with the surrounding tissues.     

Hydrothermal synthesis of yttria stabilized ZrO2 nanoparticles in subcritical and supercritical water using a flow reaction system

Yttria stabilized zirconia nanoparticles have been prepared by hydrothermal flow reaction system under subcritical and supercritical conditions. ZrO(NO₃)₂/Y(NO₃)₃ mixed solutions were used as starting materials. Reaction temperature was 300–400 °C. Reaction time was adjusted to 0.17–0.35 s. Based on the residual Zr and Y concentrations, the complete conversion of zirconium was achieved irrespective of pH and hydrothermal temperature, whereas the conversion of yttrium increased with an increase in pH and hydrothermal temperature. Stoichiometric solid solution was achieved at pH>8. XRD results revealed that tetragonal zirconia can be formed regardless of yttrium content, where the tetragonality was confirmed by Raman spectroscopy. The average particle size estimated from BET surface area was around 4–6 nm. Dynamic light scattering particle size increased with the solution pH owing to the aggregation of primary particles. TG-DTA analyses revealed that weight losses for adsorbed water and hydroxyl groups decreased with hydrothermal temperature.     

An investigation of post treatment on properties and structure of ultrahigh molecular weight polyethylene parts prepared by selective laser sintering for biomedical application

Combined with customization advantage of selective laser sintering (SLS) and excellent performance of ultrahigh molecular weight polyethylene (UHMWPE), it is possible to meet the requirements of artificial joints for biomedical application. However, high viscosity of UHMWPE melt limits the strength of UHMWPE sintered parts. Inspired from metal and ceramic materials, this work aims to improve the performance of UHMWPE parts prepared by SLS using post treatment methods, including heat treatment and hot isostatic pressure (HIP) treatment. Consequently, HIP treatment shows superiority on promoting the performance of UHMWPE sintered parts compared with heat treatment. With the condition of temperature and isostatic pressure, a novel definition of “bonding neck” is given to explain the enhancement of cohesion between each UHMWPE particle in different post treatment. Without any fortifier, the biological safety of artificial joints manufactured by SLS is further guaranteed. Under the isostatic pressure of 12 MPa and temperature of 185°C in HIP treatment, the mechanical strength, tribological performance and other properties are improved dramatically. The tensile strength of the specimen is up to 8.0 MPa, the elongation at break is 99.3%, the impact strength is 8.8 MPa, the friction coefficient is 0.11, the wear rate is 9.3 × 10^?4 mm³/Nm and samples do not show cytotoxicity at the same time.     

Y2O3/ZrO2中空纤维陶瓷膜的制备与表征

本文结合相转化技术和干湿法纺丝工艺制备了以YSZ(以摩尔分数为8%的Y2O3稳定的ZrO2)为原料的中空纤维陶瓷膜, 考察了YSZ粉体的粒度分布和形貌, 并研究了YSZ中空纤维陶瓷膜的气密性、 孔特性、 机械性能、 微观结构及晶型变化等.     

Recovery and stabilization of heavy metal sludge (Cu and Ni) from etching and electroplating plants by electrolysis and sintering

This work dealt with the recovery and stabilization of the sludge with heavy metals (Cu and Ni) produced from etching and electroplating plants. The heavy metals in the sludge were deprived of by acid leaching, followed by precipitation with 28% NH₄OH, and finally by electrolysis. In the electrolysis, the recovery percentage and purity were investigated at different electronic currency and temperature. The metal-deprived sludge was stabilized by mixing with glass powder and clay, followed by sintering at high temperature. How the ratio of glass powder to metal-deprived sludge affected final products (sludge bricks) was explored, in terms of specific gravity, absorption capacity, unconfined compressive strength, morphology, the volume shrinkage ratio and burn-up ratio. The volume shrinkage ratio and burn-up ratio of sludge bricks increased with metal-deprived sludge contents. The heavy metal remaining in sludge bricks was assessed through TCLP (toxicity characteristic leaching procedure) and by the analysis of SEM and EDX. The results from TCLP showed that the contents of leached metals were all below the regulatory criteria. This fact approved the feasibility of our method.     

Sulfated zirconia (SO4/ZrO2) as a reusable solid acid catalyst for the Mannich-type reaction between ketene silyl acetals and aldimines

Sulfated zirconia (SO₄/ZrO₂) catalyzed Mannich-type reactions of ketene silyl acetals and aldimines proceeded smoothly at room temperature to afford β-amino esters in good to high yields. In addition, the heterogeneous solid acid catalyst SO₄/ZrO₂ was easily recovered from the reaction mixture and then reused without significant loss of effectiveness.     

Poly(o-methoxyaniline) Chain Degradation Based on a Heat Treatment (HT) Process: Combined Experimental and Theoretical Evaluation

Poly(o-methoxyaniline) emeraldine-salt form (ES-POMA) was chemically synthesized using hydrochloric acid and subjected to a heat treatment (HT) process for 1 h at 100 °C (TT₁₀₀) and 200 °C (TT₂₀₀). The HT process promoted a progressive decrease in crystallinity. The Le Bail method revealed a decomposition from tetrameric to trimeric-folded chains after the HT process. The unheated POMA-ES presented a globular vesicular morphology with varied micrometric sizes. The heat treatment promoted a reduction in these globular structures, increasing the non-crystalline phase. The boundary length (S) and connectivity/Euler feature (χ) parameters were calculated from the SEM images, revealing that ES-POMA presented a wide distribution of heights. The TT₁₀₀ and TT₂₀₀ presented a narrow boundary distribution, suggesting smoother surfaces with smaller height variations. The UV-VIS analysis revealed that the transition at 343 nm (nonlocal π → π*) was more intense in the TT₂₀₀ due to the electronic delocalization, which resulted from the reduced polymer chain caused by the HT process. In addition to the loss of conjugation, counter ion withdrawal reduced the ion-chain interaction, decreasing the local electron density. This result shows the influence of the chlorine counter ions on the peaks position related to the HOMO → LUMO transition, since the π → polaron transition occurs due to the creation of the energy states due to the presence of counter ions. Finally, the electrical conductivity decreased after the HT process from 1.4 × 10⁻⁴ S.cm⁻¹ to 2.4 × 10⁻⁶ S.cm⁻¹ as result of the polymer deprotonation/degradation. Thus, this paper proposed a systematic evaluation of the POMA molecular structure and crystallite size and shape after heat treatment.     

Studies on the syntheses of polymetalloxanes and their properties as a precursor for amorphous oxide. VII. Preparation and properties of polyzirconoxanes as a precursor for zirconia fibers by the hydrolysis of bis (ethyl acetoacetato) zirconium dialkoxide

Acid-catalyzed hydolysis of bis(ethyl acetoacetato) zirconium dialkoxide in methanol or THF was investigated. The hydrolysis of the chelates in the molar ratios of H₂O/ chelate = 1.0–2.0 and HCl/chelate = 0.1–0.2 provided concentrated solutions (ca. 83 wt %) of polyzirconoxanes (PZO) which showed excellent spinnability and stability to self-condensation. Continuous gel fibers were prepared by dry spinning the solutions. Polyzirconoxanes were isolated as powders when the concentrated solution was precipitated with hexane. Silylation allowed the investigation of the structure of PZO. It was confirmed to be the polymers of a low degree of polymerization with the ligand and hydroxy group as pendants. © 1992 John Wiley & Sons, Inc.     

Mercury(II) complexes of stabilized phosphine-phosphonium ylide derived from bis(diphenylphosphino)methane: Synthesis, spectra and crystal structures

The reaction of a mixed phosphine-phosphonium ylide, PPh₂CH₂PPh₂C(H)C(O)Ph with mercury(II) halides in methanol under mild conditions yielded the P, C-chelated complexes, [HgX₂(PPh₂CH₂PPh₂C(H)C(O)Ph)] where X = Cl (2), Br (3), I (4). Single crystal X-ray diffraction studies reveal the presence of mononuclear complexes containing Hg atom in a distorted tetrahedral environment and long Hg-C_ylide bond. The five-membered chelate rings in the two independent molecules present in the asymmetric unit of 4 adopt ‘envelope’ and ‘twist’ conformations. Spectroscopic studies also indicate the weaker Hg-C bonding. Additionally, the molecular structure of the free ylide (1) is also discussed.     

Thermogravimetric investigation ofwastes from electrical and electronic equipment (WEEE)

Two components of electronic wastes (sample A – a mixture of three types of printed circuit boards, sample B – a mixture of electronic junctions with metal wires) were investigated using thermogravimetric analysis (TG). Thermogravimetric and derivative thermogravimetric data (TG and DTG) give information on the thermal stability of A and B samples and allows finding the correct conditions for their degradation using pyrolysis in an experimental system, built on the laboratory scale for utilization of hazardous wastes. X-ray fluorescence measurements prove that brominated flame retardant is present in sample A, whilst chlorinated flame retardant is a probable component of sample B. Preliminary liquid chromatography of oil products obtained as a result of thermal waste degradation shows that the hydrocarbons released during pyrolysis could be used as a fuel.     

Structure and property development in poly(p-phenylene terephthalamide) during heat treatment under tension

The evolution of several structural characteristics during isothermal heat treatment of poly(p-phenylene terephthalamide) was studied. In this work, heat treatment was interrupted after different treatment times, with the specimens immediately quenched to room temperature. These specimens were then characterized by tensile testing, wide- and small-angle x-ray scattering, and optical microscopy. Structural parameters obtained from these measurements relate to crystal perfection (via the paracrystalline axial distortion parameter), axial crystallite size, transverse crystallite size, degree of chain misorientation, and degree of pleating. Structural and mechanical parameters were then plotted against heat-treatment time to obtain kinetic isotherms for each parameter. The kinetics of the removal of chain misorientation parallels that of tensile modulus increase under all conditions. Of the other structural parameters, only the kinetics of pleat removal mimics that of modulus change, indicating that pleat removal is the effective cause of increased chain alignment and thereby of increased axial stiffness. ©1995 John Wiley & Sons, Inc.     

Structure and electrical properties of single-phase cobalt manganese oxide spinels Mn3−xCoxO4 sintered classically and by spark plasma sintering (SPS)

Cobalt manganese oxide spinels Mn_3−xCo_xO₄ (with 0.98?x?3) were prepared by the thermal decomposition in air of oxalate precursors. The influence of the thermal treatments on the structure of these materials is emphasized. Single-phase ceramics were obtained after optimization of the sintering parameters. A precise phase diagram for the Co-Mn-O system is proposed according to thermal stability and structure of oxide powders. The electrical measurements on single-phase ceramics show that low values of resistivity can be achieved. The conduction could take place through jumps of polarons between Mn³⁺ and Mn⁴⁺ on octahedral sites. These compounds present interesting electrical characteristics for negative temperature coefficient (NTC) thermistor applications.     

DNA and RNA binding studies on a novel bromo-bridged dimeric copper(II) complex stabilized from a Schiff base ligand

Abstract

A novel red copper(II) compound, bis(μ-bromo)bis(2-(benzothiazol-2-yl-hydrazono)-1,2-diphenyl-ethanone)-dicopper(II) (1), has been fostered by equimolar reaction of a Schiff-base ligand, 2-(benzothiazol-2-yl-hydrazono)-1,2-diphenyl-ethanone (LH), with copper(II) bromide in satisfactory yield. 1 has thoroughly been characterized by C, H and N elemental analyses, FT-IR and UV-vis (both in solid state and in solution) spectroscopies, and room-temperature magnetic susceptibility and conductivity measurements. Dimeric 1 bears symmetric rare bromo-bridges in its crystal structure. 1 retains its solid-state identity even in a protic solvent like methanol. 1 in methanol displays two-step one-electron redox response. Theoretical calculations based on DFT were executed to probe the electronic structure of 1 and to augment its color. DNA- and RNA-binding aspects of both LH and 1 have been explored. Thermodynamic binding parameters have been determined. LH is a major-groove binder to DNA, while 1 manifests itself as a minor-groove binder. This binding has been corroborated through molecular docking. Nucleic acid binding aspect of such type of rare bromo-bridged red copper(II) dimer is unprecedented.     

Designing of Zn (II)-based novel coordination polymer (CP): Synthesis,characterization, and heavy metal removal from water

A new coordination polymer, Zn-(OC-AMAM-CO) CP, has been synthesized from Zn (II) as ionic node and 2,2′-((1,2-phenylenebis [azanediyl])bis (carbonyl))dibenzoic acid, (OC-AMAM-CO), as a new linker, where (OC-AMAM-CO) has been synthesized as an amide product through condensation reaction of phthalic acid and o-phenylenediamine. The amide product (OC-AMAM-CO) and Zn-(OC-AMAM-CO) CP were characterized via FTIR and PXRD analyses, and Zn-(OC-AMAM-CO) CP was further characterized via SEM/EDX and XPS analyses. Moreover, DFT study was performed to shed light on the both structures of (OC-AMAM-CO) and Zn-(OC-AMAM-CO). PXRD analysis revealed the successful syntheses of the new linker (OC-AMAM-CO) and Zn-(OC-AMAM-CO) CP where the new CP is crystalline. DFT study revealed that the 3D topological structure assembled through coordination, π–π stacking, and hydrogen bonding. Zn-(OC-AMAM-CO) CP was applied as an adsorbent for the removal of Cu (II) from water as it has abundant chelating groups that serve as adsorptive coordinating sites. Isotherm study revealed the obedience of Cu (II)/Zn-(OC-AMAM-CO) CP adsorption system to Langmuir modeling with adsorption capacity of about 55 mg/g. A kinetic study showed that the rate of adsorption was a pseudo-first-order type. Further, adsorption process was found to be strongly diffusion dependent.     

Formation of micro-crystals in poly(ethylene terephthalate) fiber by a short heat treatment and their influence on the mechanical properties

The morphological change of poly(ethylene terephthalate) (PET) fibers by a short heat treatment under free-to-relax condition (i.e., without mechanical constraints imposed on the fibers during the treatment) was investigated. Heat treatment on polymeric fibers, in particular free-to-relax condition, has been known to lower the initial elastic modulus due to the relaxation of the amorphous molecules; however a short heat treatment at 190 °C for 1.2 s in the present study increased the initial modulus, whereas the yield strength was decreased significantly. During the short heat treatment, the PET molecules in the PET fibers were relaxed and became crystallized to some extent. The PET chains in the amorphous regions were also relaxed, promoting the formation of micro-crystals. These micro-crystals in the amorphous region can explain the increase in the initial modulus. The mechanism for such unusual behavior was investigated using mechanical tests, thermal stress analysis, wide and small angle X-ray diffraction, and FTIR spectrum analysis. Furthermore, a morphological model for the molecular arrangements in the PET fibers due to the short heat treatment is proposed, offering the possibility of developing PET fibers with shape retention function that can behave similarly to metal fibers.     

Biosorption of copper (II) and lead (II) from aqueous solutions by nonliving green algae Cladophora fascicularis: Equilibrium, kinetics and environmental effects

Biosorption of Cu²⁺ and Pb²⁺ by Cladop- hora fascicularis was investigated as a function of initial pH, initial heavy metal concentrations, temperature and other co-existing ions. Adsorption equilibriums were well described by Langmuir and Freundlich isotherm models. The maximum adsorption capacities were 1.61 mmol/g for Cu²⁺ and 0.96 mmol/g for Pb²⁺ at 298 K and pH 5.0. The adsorption processes were endothermic and biosorption heats calculated by the Langmuir constant b were 39.0 and 29.6 kJ/mol for Cu²⁺ and Pb²⁺, respectively. The biosorption kinetics followed the pseudo-second order model. No significant effect on the uptake of Cu²⁺ and Pb²⁺ by co-existing cations and anions was observed, except EDTA. Desorption experiments indicated that Na₂EDTA was an efficient desorbent for the recovery of Cu²⁺ and Pb²⁺ from biomass. The results showed that Cladophora fascicularis was an effective and economical biosorbent material for the removal and recovery of heavy metal ions from wastewater.     

硝酸铈及热处理对化学镀Ni-W-P合金的性能影响

为提高化学镀Ni-W-P镀层的耐蚀性和耐磨性,拓宽其应用,采用电化学方法和热处理等手段,研究了镀液中添加剂硝酸铈(Ce(NO3)3)的质量分数和热处理对化学镀Ni-W-P镀层的沉积速度、孔隙率、失重腐蚀速度、腐蚀电位、腐蚀电流、交流阻抗、显微硬度、摩擦系数等性能的影响。结果表明:添加1.0 wt%Ce(NO3)3时,所得镀层的沉积速度最大(36.5 g/m2·h),孔隙率最低(0.8个/cm2),耐腐蚀性能最好。镀层的组织均匀、致密、无缺陷和非晶态结构是其耐蚀性能高的重要原因。100~600℃热处理后,镀层硬度和耐磨性有所提高,而400℃热处理之后,合金显微硬度高达1100 HV,是镀态的1.8倍。     

Effects of Alterations to Ziegler–Natta Catalysts on Kinetics and Comonomer (1‐Butene) Incorporation

Various MgCl₂‐supported Ziegler–Natta (ZN) catalysts are synthesized with the intention to influence polymerization performance and 1‐butene incorporation in an ethylene copolymer. Modifications are introduced during different steps in the synthesis process, namely support preparation, titanation, and catalyst workup. While multiple different effects are observed upon modification, heat treatment during titanation shows the greatest impact. Increasing the heat‐treatment temperature increases polymerization activity. More importantly, the 1‐butene distribution can be shifted toward a more homogeneous profile. The amount of 1‐butene incorporated is similar to both for short‐ and for very long‐chain molecules. This behavior has so far been known only from metallocene‐based polyethylene and suggests that active sites are distributed more homogeneously in the ZN catalyst.