Initial Ti Research Articles

Investigating the laminar burning velocity of NH3/H2/air using the constant volume method: Experimental and numerical analysis

The fundamental combustion field of ammonia-hydrogen fuel is being extensively researched. However, studies on the laminar burning velocity (LBV) under high pressure with varying hydrogen concentration conditions are relatively scarce. This study innovatively used the constant volume method (CVM) to measure LBV of ammonia-hydrogen fuels with various hydrogen concentrations XH2 = 15%–30%, initial temperatures Ti = 298–428 K, initial pressures Pi = 1–3 bar, and equivalence ratios ϕ = 0.8–1.4. The LBV of the fuel mixture up to the temperature and pressure of 540 K and 7 bar under isentropic adiabatic assumption was determined with the CVM method. The results illustrate that the enhancing effect of hydrogen concentration on LBV is suppressed under high pressures, supporting the argument that the equivalence ratio associated with the maximum LBV is solely determined by the initial fuel composition. Chemical kinetics simulations were also analyzed including flame structure, sensitivity analysis, and reaction pathways. It indicated that the elementary reaction H + O2<=>O + OH predominantly governs the LBV of ammonia-hydrogen. An increase in hydrogen concentration intensifies this process by boosting the concentration of free radical hydrogen, albeit with a concomitant rise in NO emissions due to nitrogen-containing radical oxidation. Conversely, an increase in initial pressure diminishes NO emissions by strengthening the pathway from NO to NNH. The findings of this study enhance the LBV database of ammonia-hydrogen fuel at high pressures and high temperatures, and can further act as a reference for other experiments.

HIDALGO: A FUN object from the earliest epoch of the solar system’s history

Chemical and isotopic measurements of HIDALGO, a stoichiometrically pure hibonite inclusion found in the matrix of the Dar al Gani 027 meteorite, were conducted by secondary ion mass spectrometry to investigate its origin and evolution. HIDALGO is characterized by large mass-dependent isotope fractionations in O, Ca, and Ti, as well as large negative anomalies in neutron-rich 48Ca and 50Ti, making it the newest member of the HAL-type FUN inclusions. The highly fractionated Ca and Ti isotopes but unfractionated Mg isotopes are consistent with HIDALGO being a residue from an extensive evaporation event, during which large fractions of initial Ca and Ti, and essentially all the initial Mg, in the precursor material were lost. HIDALGO appears to have incorporated live 26Al at a higher level than other HAL-type inclusions, but still at a lower amount compared to the Solar System’s initial 26Al abundance typically found in non-FUN CAIs. Interestingly, the inferred 10Be abundance in HIDALGO is comparable to the values observed in the majority of CV3 CAIs but ∼ 2.5 times higher than those in HAL-type samples. HIDALGO’s unusual 26Al/27Al and 10Be/9Be ratios, together with the 48Ca-50Ti anomalies, can be best explained by the formation of its precursor material in the isotopically heterogeneous solar nebula. Finally, large 7Li excesses correlating with Be/Li were found in HIDALGO, a behavior that can be interpreted as due to in-situ decay of live 7Be. Charged particle spallation of initially Li-free HIDALGO can simultaneously account for the inferred 7Be abundance and the measured Li elemental concentration. The consistency between the measurement and spallation calculation results provides support for the prior existence of 7Be in HIDALGO, possibly produced by irradiation close to the Sun

Friction stir processing of pure titanium/nanodiamonds nanocomposites: Microstructure, tribological and corrosion properties

A titanium matrix surface nanocomposite with uniformly distributed nanodiamonds was developed using friction stir process for the first time. A dual phase (α+β) microstructure containing ultrafine equiaxed grains was formed within the matrix after three passes. The mean grain sizes were measured to be 0.7 and 0.9 μm for α and β phase, respectively. The stabilization of the β phase at room temperature was discussed, relying on post-processing cooling rate and the diffusion of W elements from the tool to the matrix. The processed nanocomposite exhibited a microhardness value of 618 Hv in the stir zone, which is 4 and 2.6 times to the initial material and pure Ti processed (without nanodiamonds), respectively. Upon friction stir processing of pure titanium (without nanodiamonds), an ultrafine-grained structure with an average size of 2.4 μm was produced, which led to an increase in microhardness up to 238 Hv. Based on conducted tribological evaluations, the processed surface nanocomposite exhibited a significant decrease in friction coefficient and wear weight loss. The results indicated a 47% decrease in friction coefficient and a 75% reduction in wear weight loss compared to the initial material. The investigation of worn surfaces implied that the wear mechanism was altered from delamination in initial pure Ti to abrasive wear in the Ti/NDs processed nanocomposite. Corrosion testing, including electrochemical impedance spectroscopy and potentiodynamic polarization techniques, revealed that Ti/NDs nanocomposite processing mitigated the material corrosion resistance, which were ascribed to the developed ultrafine grained structure as well as NDs nanoclusters to galvanic corrosion activation.

Co-pyrolysis behavior of municipal solid waste and food waste residue: A thermogravimetric study to discern synergistic effect

Effective solid waste disposal necessitates suitable combination and clean conversion technologies to maximize resource utilization. Thus, this study investigates the behavior of co-pyrolysis in municipal solid waste (MSW) and food waste (FW) via thermogravimetric analysis, aiming to discern synergistic effects and optimize waste to energy conversion. The impacts of heating rate and blending ratios were evaluated under an inert N2 atmosphere, within a temperature range of 30–900℃, during single and combined pyrolysis processes respectively. Results revealed slight variations in weight loss patterns and thermal decomposition behavior. When heating rate increased from 10 to 30℃.min−1, decomposition process delayed, resulting in higher initial (Ti), peak (TP), and final (Tf) temperatures due to inadequate heat transfer. As food waste increased, mass loss rose and favorable synergistic effect was observed at 20 % FW during medium temperatures, while other blends showed inhibitory effects. The pyrolytic index (D) rose nonlinearly from 6.29 × 10−7 to 7.72 × 10−7 with a higher FW proportion, peaking at 20 % FW, suggesting an optimal MSW and FW mixing ratio. This blend also exhibited the lowest activation energy, indicating a more efficient thermal decomposition process. Those outcomes offer crucial insights for optimizing co-pyrolysis systems and provide essential information for co-disposal of MSW and FW, potentially reducing pollutant emissions and enhancing waste to energy conversion.

Titanium Silicide: A Promising Candidate of Recombination Layer for Perovskite/Tunnel Oxide Passivated Contact Silicon Two-Terminal Tandem Solar Cells.

This study proposes a titanium silicide (TiSi2) recombination layer for perovskite/tunnel oxide passivated contact (TOPCon) 2-T tandem solar cells as an alternative to conventional transparent conductive oxide (TCO)-based recombination layers. TiSi2 was formed while TiO2 was made by oxidizing a Ti film deposited on the p+-Si layer. The reaction formation mechanism was proposed based on the diffusion theory supported by experimental results. The optical and electrical properties of the TiSi2 layer were optimized by controlling the initial Ti thicknesses (5-100 nm). With the initial Ti of 50 nm, the lowest reflectance and highly ohmic contact between the TiO2 and p+-Si layers with a contact resistivity of 161.48 mΩ·cm2 were obtained. In contrast, the TCO interlayer shows Schottky behavior with much higher contact resistivities. As the recombination layer of TiSi2 and the electron transport layer of TiO2 are formed simultaneously, the process steps become simpler. Finally, the MAPbI3/TOPCon tandem device yielded an efficiency of 16.23%, marking the first reported efficiency for a device including a silicide-based interlayer.

Control of Aluminum and Titanium Contents in the Electroslag Remelting of ATI 718PlusTM Alloy.

The burning loss of Al and Ti elements in superalloys during electroslag remelting has become a prevalent issue. And the existing slag system is not suitable for smelting the ATI 718PlusTM alloy. Therefore, it is imperative to develop a new slag system for smelting the ATI 718PlusTM alloy. To mitigate this issue, a thermodynamic model of the oxidation reaction of Al and Ti at the slag and alloy interface was established based on the ion and molecule coexistence theory (IMCT). The thermodynamic model was used to investigate the correlation between the equilibrium content of Al and Ti, slag composition, smelting temperature, and initial Al and Ti content of the electrode. The results indicate that while increasing the smelting temperature can effectively inhibit the burning loss of Al, it will exacerbate the burning loss of Ti. Increasing CaO and Al2O3 contents can inhibit the Al burning loss, while an increase in the TiO2 content can inhibit the Ti burning loss. Although an increase in the MgO content results in the burning loss of Al, its impact on the Al is minimal. The burning loss of Al and Ti was not affected by the change in the CaF2 content. The high Al content in ATI 718PlusTM makes it prone to burning loss of Al during the electroslag remelting. The combustion loss of Al can be reduced by increasing the Ti content in the electrode or adding a suitable amount of aluminum powder to the slag system. The accuracy of the model had been validated through experimental verification.

Synthesis of MAX phases Ti2AlC and V2AlC by carburization of hydrogenated alloys Ti2AlHx and V2AlHx

The present study shows that Ti2AlC and V2AlC could be synthesized by carburization of special precursor alloys. The initial Ti and V were hydrogenated, milled, and then mixed with Al particles. The prepared mixtures were annealed under vacuum and the temperature of 1000 °C was sufficient for alloy formation. The produced Ti2AlHx and V2AlHx alloys were brittle, which enabled crushing and mixing with carbon black. The obtained powders were heated under vacuum to nucleate the MAX phases. The annealing at 1100 °C was optimal because at lower and higher values of temperature either the carburization process was not complete or phase decomposition was observed. Additional experiments for synthesis of layered ceramics from the mixtures of TiHx/VHx, Al, and C were characterized with a slower reaction kinetics. The analysis of isothermal oxidation demonstrated smaller exothermic effects for Ti2AlHx compared to TiHx at 200–600 °C, while V2AlHx had lower intensities at 200–400 °C but higher at 500–600 °C with respect to VHx.

Influences of alloying composition and cooling rate on precipitation behaviors of primary Al3Zr-D023 intermetallics in Al-Mg-Li-Zr alloys

In the industrial process, the potential benefit of Al3Zr precipitates is usually weakened because coarse Al3Zr precipitates have no positive effect on the dynamic recovery, recrystallization and grain growth. Effects of alloying composition and cooling rate on precipitation and growth behaviors of primary Al3Zr-D023 intermetallics were investigated, especially in a large compositional space. Four types of elements exist in the Al3Zr-D023 phase. Increasing initial Mg, Li, Zr, and Ti contents is beneficial to increase the start precipitation temperature of Al3Zr-D023 particles. Increasing initial Mg, Li, Zr, Ti contents and reducing cooling rate are beneficial to increase the mean length, decrease the nucleation rate and the number density of Al3Zr-D023 precipitates. Furthermore, Zr and Ti element contents show a strong positive correlation with the start precipitation temperature and the final length of Al3Zr-D023 precipitates. Reducing slightly initial Ti content is beneficial to reduce the final length of Al3Zr-D023 precipitates. Furthermore, two empirical equations were obtained using the multiple linear regression method, which reveal the complex interactions rather than single-element effect of Mg, Li, Zr, and Ti.

Transport kinetics of protium and deuterium in titanium: Experiments and modeling

We conducted absorption experiments on Ti using hydrogen isotopes, protium and deuterium, to gain insights into the kinetics of hydrogen atoms, particularly across the Ti surface. Rather than relying on various surface pretreatments, we identified the initial temperature of Ti in vacuum as the determining factor in achieving a high absorption rate and content. Specifically, we found that the initial Ti temperatures of approximately 900 and 980 °C are optimal for protium and deuterium, respectively, likely due to sufficient removal of the native surface oxide on Ti. The dependence of the absorption rate and amount of hydrogen isotopes on the temperature during absorption was partially explained by the phase transformation and exothermicity of the hydrogenation reaction. Moreover, this dependence strongly indicated the existence of a tunneling transport process. Additionally, we developed a kinetic model for hydrogen isotope transport in Ti to conduct numerical simulations. The absorption curves, calculated using the developed model, closely matched a series of experimental curves obtained at different temperatures. These curves were from an identical set of equations and kinetic parameters for both protium and deuterium. Our numerical kinetic model has the potential to serve as a valuable simulation tool for various applications, such as the design of high-performance hydrogen storage systems and maintenance strategies against hydrogen embrittlement of structural materials.

The effect of the concentration of plastic waste on the formation of reaction products of the Ti–PET system

The paper presents research results of the synthesis, phase composition, and structure of products obtained by highly exothermic reactions between Ti and C10H8O4 mixture components, depending on the plastic waste concentration and Ti powder dispersiveness, density of initial samples, and synthesis medium. The dependence of the phase composition and structure of the synthesis products on the concentration of the polymer (plastic) component in the initial Ti -PET (C10H8O4) system was found. When the plastic waste content is 20 wt% to 25 wt%, synthesis products contain TiC0.5O0.5–TiC0.6–0.75 particle agglomerates. Further growth in the polyethylene terephthalate content from 30 wt% to 45 wt% leads to the formation of synthesis products consisting of titanium carbide (TiC0.6–1.0). The gaseous byproduct composition of the exothermic reaction is investigated for the Ti–C10H8O4 mixture composition. It is found that the gaseous by-product mostly contains hydrogen and carbon monoxide as well as impurities of different hydrocarbons (methane, acetylene, ethane, ethene) and carbon dioxide. The maximum adiabatic temperature of the gas combustion temperature is 2080 oC, which demonstrates the possibility of using gas as a fuel for energy generation devices. Based on the data obtained, it is possible to create a basis for a new plastic waste technology to fabricate carbide-containing materials.

Quantum field theory of physical and purely virtual particles in a finite interval of time on a compact space manifold: diagrams, amplitudes and unitarity

We provide a diagrammatic formulation of perturbative quantum field theory in a finite interval of time τ, on a compact space manifold Ω. We explain how to compute the evolution operator U(tf, ti) between the initial time ti and the final time tf = ti + τ, study unitarity and renormalizability, and show how to include purely virtual particles, by rendering some physical particles (and all the ghosts, if present) purely virtual. The details about the restriction to finite τ and compact Ω are moved away from the internal sectors of the diagrams (apart from the discretization of the three-momenta), and coded into external sources. Unitarity is studied by means of the spectral optical identities, and the diagrammatic version of the identity U†(tf, ti)U(tf, ti) = 1. The dimensional regularization is extended to finite τ and compact Ω, and used to prove, under general assumptions, that renormalizability holds whenever it holds at τ = ∞, Ω = ℝ3. Purely virtual particles are introduced by removing the on-shell contributions of some physical particles, and the ghosts, from the core diagrams, and trivializing their initial and final conditions. The resulting evolution operator Uph(tf, ti) is unitary, but does not satisfy the more general identity Uph(t3, t2)Uph(t2, t1) = Uph(t3, t1). As a consequence, Uph(tf, ti) cannot be derived from a Hamiltonian in a standard way, in the presence of purely virtual particles.

Catalyzing Benzoxazine Polymerization with Titanium-Containing POSS to Reduce the Curing Temperature and Improve Thermal Stability.

Trisilanolphenyl-polyhedral oligomeric silsesquioxane titanium (Ti-Ph-POSS) was synthesized through the corner-capping reaction, and Ti-Ph-POSS was dispersed in benzoxazine (BZ) to prepare Ti-Ph-POSS/PBZ composite materials. Ti-Ph-POSS could catalyze the ring-opening polymerization (ROP) of BZ and reduce the curing temperature of benzoxazine. In addition, Ti immobilized on the Ti-Ph-POSS cage could form covalent bonds with the N or O atoms on polybenzoxazine, improving the thermal stability of PBZ. The catalytic activity of the Ti-Ph-POSS/BZ mixtures was assessed and identified through 1H nuclear magnetic resonance (1H-NMR) and Fourier-transform infrared (FTIR) analyses, while thermogravimetric analysis (TGA) and dynamic mechanical analysis (DMA) were used to determine the thermal properties of the composite. It was found that PBZ exhibited a higher glass transition temperature (Tg) and better thermal stability when Ti-Ph-POSS was added. The curing behavior of the Ti-Ph-POSS/BZ mixtures showed that the initial (Ti) and peak (Tp) curing temperatures sharply decreased as the content of Ti-Ph-POSS and the heating rate increased. The curing kinetics of these Ti-Ph-POSS/BZ systems were analyzed using the Kissinger method, and the morphology of Ti-Ph-POSS/PBZ was determined via scanning electron microscopy (SEM). It was found that the Ti-Ph-POSS particles were well distributed in the composites. When the content exceeded 2 wt%, several Ti-Ph-POSS particles could not react with benzoxazine and were only dispersed within the PBZ matrix, resulting in aggregation of the Ti-Ph-POSS molecules.

Synthesis and characterization of eco‐friendly poly(ε‐caprolactone) plasticizer facilitating phthalate‐free polyvinyl chloride with novel star/net‐shaped structures

AbstractPotential migration and toxicity limited applications of traditional plasticizers like bis(2‐ethylhexyl) phthalate (DEHP) in food packing and medical machinery and so forth. Safe and feasible bio‐based plasticizers have recently moved into the limelight of research hotspot. Here, we designed series polyester plasticizers of various branches with star‐shaped poly(ε‐caprolactone) (SPCLs) and net‐shaped poly(ε‐caprolactone) (NPCLs) structures by one‐pot solvent‐free synthesis with glycidol and polyglycerol as initiators. Structures of SPCLs and NPCLs were further verified by FTIR, 1H NMR, and 13C NMR. Moreover, the properties of the plasticizers and plasticized PVC were evaluated by differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), thermogravimetric analysis (TGA) and tensile test. PVC films plasticized with the SPCLs or NPCLs exhibited increased plasticizing effect, compatibility, flexibility and cold resistance. The lowest Tg value of plasticized PVC samples (PVC/NPCL1‐C4) was −45.3°C, which made the plasticization efficiency reach 122.5%. In particular, PVC/SPCLs‐C4 (SPCL2‐C4) had 107% higher elongation at break than PVC/DEHP. Meanwhile, the initial decomposition temperature Ti value of the PVC blends maximum increased from 240 to 328°C when DEHP was completely replaced by SPCLs or NPCLs, indicating improved thermal stability of the plasticizer. Overall, “green” plasticizers with fining topological branch design would be promising to partially replace petroleum‐based plasticizers.

Frontloading SITA-Faster Can Increase Frequency and Reliability of Visual Field Testing at Minimal Time Cost

To report the outcomes of frontloaded visual field (VF) testing (2 tests per eye on the same visit) over 2 longitudinal, consecutive visits using SITA-Faster (SFR) in terms of global indices, reliability metrics, and test duration. Prospective longitudinal study. A total of 902 eyes of 463 subjects with normal, suspect, or manifest glaucoma. Two intravisit SFR VF tests (T1 and T2) per eye at an initial (Ti) and follow-up (Tf) visit. Intra- and intervisit global indices, reliability metrics, and test durations. The mean age of the subjects was 63.6 years, and 58.3% were male. Seven hundred ninety eyes (87.4%) had a diagnosis of glaucoma or glaucoma suspicion. The mean duration between visits was 265.0 (standard deviation 98.8) days. In total, 3608 VF tests were analyzed, with the correlation of mean deviation (MD) values of the frontloaded tests at each visit high (T1/T2 MD correlation at initial visit r= 0.83, root mean squared error [RMSE]= 1.26, follow-up visit r= 0.83, RMSE= 1.25, P < 0.0001) and greater than the correlation of MD between visits (Ti1/Tf1 MD correlation r= 0.72, RMSE= 1.31). There was a significant intra-visit decrease in rates of abnormally high sensitivity in the glaucoma hemifield test (3.2% vs. 1.6%, P= 0.0023) and rates of unreliable test results (15.4% vs. 9.2%, P= 0.002) from T1 to T2 in both visits, with a corresponding significant decrease in MD (-1.28 dB vs. -1.68 dB, P < 0.0001) and VF index (P= 0.03). The mean duration of each SFR test was 132.6 (SD 27.2) seconds. Frontloading VFs using SFR produced sets of repeatable perimetric data with significant improvement of reliability indices from the first to second test. This may help increase testing frequency at minimal time cost to meet recommended guidelines and for evaluating patients prone to high variability. The author(s) have no proprietary or commercial interest in any materials discussed in this article.

Omega Phase Formation and Mechanical Properties of Ti–1.5 wt.% Mo and Ti–15 wt.% Mo Alloys after High-Pressure Torsion

The paper analyzes the effect of severe plastic deformation by the high-pressure torsion (HPT) on phase transformations, in particular, on the formation of the ω-phase, and on mechanical properties, such as hardness and Young’s modulus, in Ti alloys with 1.5 and 15 wt.% Mo. Both alloys were pre-annealed at 1000 °C for 24 h and quenched. The microstructure of the initial Ti–1.5 wt.% Mo alloy consisted of the α-phase and α’-martensite, and the initial Ti–15 wt.% Mo alloy contained polycrystalline β solid solution. The hardness tests of the samples were carried out under the load of 10 and 200 mN. The annealed alloys were subjected to HPT, and the micro- and nanohardness of both deformed samples increased up to ~1 GPa compared to their initial state. It turned out that the values of hardness (H) and Young’s modulus (E) depend on the applied load on the indenter: the higher the applied load, the lower H and higher E. It was also found that the HPT leads to the 30% increase in E for an alloy with 1.5 wt.% Mo and to the 9% decrease in E for the alloy with 15 wt.% Mo. Such a difference in the behavior of the Young’s modulus is associated with phase transformations caused by the HPT.

The Evolution of Surface Oxides during TiFe0.9M0.1 (M = Ni, Mn) Activation: An In Situ XPS Investigation

The nature of TiFe-based surface oxides and their evolution during conventional activation heat treatment were investigated in this study. The as-prepared TiFe alloy was found to possess an initial composite Ti and Fe amorphous surface oxide layer of about 6 nm. Depth profiling has shown that oxides steadily vanish with increasing depth, whereas metallic Fe contribution and mixed Ti oxides arise, before eventually being found in their metallic state at 7.5 nm. In situ XPS measurements, carried out to directly observe the evolution of oxides during the activation procedure, have indicated that the initial ternary oxide begins to transform to metallic Fe and mixed Ti oxides at a temperature as low as 200 °C. Consistent with the literature, the reduction of Ti oxides took a major turn at around 400 °C. Toward the end of the in situ measurements, oxygen was partially dissolved due to the limited measurement duration: TiO and metallic Fe remained beyond 400 °C. A similar overall reduction behavior was observed for the Ni- and Mn-substituted alloys, with a few subtle exceptions: Ni existed in its metallic state from 200 °C whereas Mn was reduced from Mn3+ to the Mn2+ state only beyond 400 °C due to a pronounced difference in the oxidation driving force of these two substitution metals.

Kinetic and mechanistic study of ultrasonic inactivation of Kunitz (KTI) and Bowman-Birk (BBI) inhibitors in relation to process-relevant parameters

In this study, quantitative monitoring of low-frequency (20 kHz) and high-frequency (355 kHz) ultrasound-induced inactivation of Kunitz (KTI) and Bowman-Birk inhibitor (BBI) using RP-HPLC was achieved, and its consistency with a traditional TI activity assay was verified. The effect of TI concentration, ultrasonic frequency, power density and pH on inactivation kinetics of KTI and BBI was explored. Results showed that the pseudo-first-order kinetic rate constants of KTI and BBI were decreased by over 60% when the initial TI concentration was increased from 100 mg/L to 1000 mg/L. Also, the amounts of inactivated KTI and BBI were increased by around 4-fold at the higher TI concentration of 1000 mg/L (20 kHz, 1.71 W/mL and pH 4). The colloidal environment and ultrasonic conditions influenced the secondary and tertiary structure and particle size of TIs in LF-induced inactivation. In comparison, the abovementioned conditions affected the oxidation of methionine and the conformational change of TIs in HF-induced inactivation.

The formation of a high-strength state in martensitic Ti Grade 4 by ECAP

This work is aimed at studying the features of initial Ti Grade 4 structure that affects the changes in its structure and properties during equal channel angular pressing (ECAP). A hot-rolled and martensite structure state, obtained in the process of water quenching from 950 °C were used as initial states. It has been established that ECAP of titanium in an initial martensitic state leads to the formation of a finer and more homogeneous structure than ECAP of a hot-rolled state. The share of high-angle boundaries reaches 80%, and the average size of structural fragments is 220 ± 80 nm. After ECAP at 400 °C, recrystallized grains are observed. As a result, the ECAP of titanium in the initial martensitic state leads to more significant hardening of up to 1100 ± 20 MPa compared to the hot-rolled state of –950 ± 15 MPa. This will make it possible to reduce the number of technological operations, as well as improve the strength resource for heat treatment aimed at ductility enhancement in ultrafine-grained titanium.

Photorefractive Response Enhancement in Poly(triarylamine)-Based Polymer Composites by a Second Electron Trap Chromophore.

Photorefractive (PR) performances are affected by the components of the photoconductor, sensitizer, nonlinear optical dye, and plasticizer. A photoconductor with high hole mobility promises a faster response time, whereas it induces higher photoconductivity, which leads to easy dielectric breakdown. Adding a second electron trap is effective in controlling photoconductivity. In this study, the role of a second electron trap 1,3,5-tri[(3-pyridyl)-phen-3-yl]benzene (TmPyPB) was investigated in a PR composite consisting of a photoconductor of poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] with a high hole mobility, a nonlinear optical chromophore of piperidinodicyanostyrene, a plasticizer of (2,4,6-trimethylphenyl)diphenylamine, and a sensitizer of [6,6]-phenyl C61 butyric acid-methyl ester. The minimum time response with the maximum optical diffraction efficiency and sensitivity was measured at a 1 wt % content of TmPyPB. These results were consistent with the number of charge carriers trapped per unit volume and per unit time Nc (cm–3 s–1), which is defined as the ratio between the initial trap density Ti (cm–3) and response time τ (s), at a 1 wt % content of TmPyPB. A faster response time of 149 μs, optical diffraction of 24.1% (external diffraction of 4.8%), and a sensitivity of 2746 cm2 J–1 were measured at 50 V μm–1 for the sample with 1 wt % TmPyPB. High loading of 5 wt % TmPyPB led to a large decrease in photoconductivity and effectively suppressed the dielectric breakdown under a stronger electric field, whereas a slower response time with lower diffraction efficiency was observed for optical diffraction.

364 A Novel Preparation of Bone Cement for Vertebroplasty: Can Strontium Folate Improve the Mechanical and Biological Properties of Calcium Phosphate Cement?

Abstract Aim Bone cements currently used for vertebral body augmentation procedures lack biological properties that allow them to osseointegrate. Strontium folate (SrFo) has been shown to increase the viability of human osteoblast (HOb) cells. The potential of a novel preparation of calcium phosphate cement (CPC) with added SrFo is explored to investigate whether SrFo can increase its biocompatibility. Method Brushite-forming CPCs with 0% (negative control) and 5% and 10% weight-weight additions of SrR (positive control) and SrFo were formulated. Initial (Ti) and final (Tf) setting times were measured. Mechanical analyses included ultimate compressive strength and plane strain fracture toughness. Topography and distribution analyses occurred during materials characterisation and in vitro analysis using scanning electron microscopy (SEM). Results There was no significant difference in the Ti between the CPCs, but significantly greater Tf for all SrFo-CPCs. There was no significant difference in the compressive strength between the CPCs, but a significantly decreased fracture toughness in all SrFo-CPCs. SEM revealed non-homogeneous structures in all SrFo-CPCs. Whilst the pH of the HOb cell culture medium remained the same for all CPCs, the proportion of dead cells was significantly higher than that of alive cells. Conclusions The addition of SrFo did not produce any significant differences in the material characteristics of the cements, nor the in vitro properties, except for a prolonged setting time. Future studies should seek to determine the osteogenic nature of SrFo by altering the formulation of the CPCs to a non-toxic preparation, such as apatite-forming cements which are known to have superior mechanical properties.