Electrochemical In Situ Fabrication of Titanium Dioxide Nanotubes on a Titanium Wire as a Fiber Coating for Solid-Phase Microextraction of Polycyclic Aromatic Hydrocarbons

A novel titanium dioxide nanotube (TiO2NTS) coated fiber for solid-phase microextraction (SPME) was prepared by in situ anodization of titanium wire in electrolyte containing ethylene glycol and ammonium fluoride (NH4F). The effects of different electrolyte solutions (NH4F and ethylene glycol) and oxidation voltages on the formation and size of TiO2NTs was studied. It was obtained from the experiment that TiO2NTs arrays were arranged with a wall thickness of 25 nm and the diameter of 100 nm pores in ethylene glycol and water (v/v, 1:1) containing NH4F of 0.5% (w/v) with a voltage of 20 V at 25 °C for 30 min. The TiO2NTs were used as solid-phase microextraction fiber coatings coupled with high-performance liquid chromatography (HPLC) in sensitive determination of polycyclic aromatic hydrocarbons (PAHs) in spiked real samples water. Under the optimized SPME conditions, the calibration curve has good linearity in the range of 0.20–500 μg·L−1, and the correlation coefficient (R2) is between 0.9980 and 0.9991. Relative standard deviations (RSDs) of 3.5–4.7% (n = 5) for single fiber repeatability and of 5.2% to 7.9% for fiber-to-fiber reproducibility (n = 3) was obtained. The limits of detection (LOD) (S/N = 3) and limits of quantification (LOQ) (S/N = 10) of PAHs were 0.03–0.05 µg·L−1 and 0.12–0.18 µg·L−1. The developed method was applied to the preconcentration and determination of trace PAHs in spiked real samples of water with good recoveries from 78.6% to 119% and RSDs from 4.3 to 8.9%, respectively.

Electrochemical Microslot Machining by Ultrasonic-Vibration-Aided Electrolyte on Nitinol Wire

In this research, the main purpose was to study the applicability of a machining method on microscale medical-equipment manufacturing. The characteristics of wire electrochemical micromachining (WECMM) against NiTi 50-50 wire was investigated. The study utilized a tungsten wire 0.03 mm in diameter as an electrode to cut a fine slot into the nickel–titanium wire. In order to reach a high-precision WECMM finish, an ultrashort pulse power generator was used as a power source to minimize the stray current effect, thus improving the machining accuracy. During the process, various machining parameters were tested for their effects on machining characteristics. In addition, ultrasonic-vibration-aided WECMM was investigated to determine whether it benefited the machining characteristics. The experiment’s results showed that under such an experiment setting, microslots can be successfully manufactured. Furthermore, with the advance adjustment of experimental parameters, the machining accuracy was improved. Finally, a fine slot was manufactured under the optimum experiment parameters and aided by ultrasonic vibration.

Free-Forging of Pure Titanium with High Reduction of Thickness by Plasma-Carburized SKD11 Dies

A tool steel type SKD11 punch was plasma carburized at 673 K for 14.4 ks at 70 Pa to make carbon supersaturation. This carburized SKD11 punch was employed for upsetting the pure titanium wire with the diameter of 1.00 mm up to the reduction of thickness by 70% in a single shot. Its contact interface to titanium work was analyzed to describe the anti-galling behavior in this forging. Little trace of titanium proved that the galling process was suppressed by the in situ solid lubrication. The isolated free carbon agglomerates are wrought as a solid lubricant to sustain the galling-free forging process. This anti-galling upsetting reduced the residual strains in the forged wires. A long titanium wire with a length of 45 mm was incrementally upset to yield the titanium ribbon with a thickness of 0.3 mm, the width of 2.3 mm, and the length of 50 mm. The grain size of original pure titanium was much reduced to 2 μm on average. A micro-pillared microtexture was imprinted onto this forged titanium ribbon.

An Anodized Titanium/Sol-Gel Composite Coating with Self-Healable Superhydrophobic and Oleophobic Property

Superhydrophobic and oleophobic surfaces have attracted increasing attention because of their self-cleaning properties. A composite coating composed of anodized titanium and sol-gel (TiAO/SG) was developed and has good superhydrophobic and oleophobic property. The anodized titanium coating was prepared on the titanium substrate and then a sol-gel layer was coated on the surface of the anodized titanium layer to obtain a composite coating with superhydrophobic and oleophobic properties. The adhesion weight of glycerol on the surface of the superhydrophobic titanium wire decreased to 4.8% of that of untreated titanium wire, which showed that the material had good oleophobic property. This new composite coating could achieve self-healing superhydrophobicity by releasing loaded perfluorodenytriethoxysilane to the surface of the coating. Given its superhydrophobicity, self-healing and wear resistance, the TiAO/SG coating was expected to achieve healable self-cleaning protection in titanium devices.

Galling-Free Cold and Warm Forging of Titanium Wires to Flat Plates by SiC-Coated SiC dies

Pure titanium and titanium alloys were difficult to be forged and press-forged because of their easiness in galling to die and punch surfaces during metal forming. β-SiC coated SiC dies were developed to perform a galling free cold forging of pure titanium wire up to the higher reduction of thickness than 50%. Since the thickness of this SiC coating was 4 mm, various cavities and micro-punches were formed into coating by micro-machining. The pure titanium and β-phase titanium alloy wires were employed as a work for cold and warm forging to investigate the effect of flow stress on the forging behavior up to the reduction of thickness by 70% under the controlled holding temperature. The contact interface of β-SiC coating to the work was precisely analyzed to describe the in situ solid lubricating process on the interface. The free carbon agglomerates isolated at the center of contact interface from the carbon supersaturated β-SiC coating, and, worked as a solid lubricant to prevent the β-SiC coating punch and die from galling during forging under high reduction of thickness.

Gate Control of Superconductivity in Mesoscopic All-Metallic Devices

The possibility to tune, through the application of a control gate voltage, the superconducting properties of mesoscopic devices based on Bardeen–Cooper–Schrieffer metals was recently demonstrated. Despite the extensive experimental evidence obtained on different materials and geometries, a description of the microscopic mechanism at the basis of such an unconventional effect has not been provided yet. This work discusses the technological potential of gate control of superconductivity in metallic superconductors and revises the experimental results, which provide information regarding a possible thermal origin of the effect: first, we review experiments performed on high-critical-temperature elemental superconductors (niobium and vanadium) and show how devices based on these materials can be exploited to realize basic electronic tools, such as a half-wave rectifier. Second, we discuss the origin of the gating effect by showing gate-driven suppression of the supercurrent in a suspended titanium wire and by providing a comparison between thermal and electric switching current probability distributions. Furthermore, we discuss the cold field-emission of electrons from the gate employing finite element simulations and compare the results with experimental data. In our view, the presented data provide a strong indication regarding the unlikelihood of the thermal origin of the gating effect.

Anti-Galling Cold, Dry Forging of Pure Titanium by Plasma-Carburized AISI420J2 Dies

A bare AISI420J2 punch often suffers from severe adhesion of metallic titanium as well as titanium oxide debris particles in dry, cold forging of biomedical titanium alloys. This punch was plasma-carburized at 673 K for 14.4 ks to harden it up to 1200 HV on average and to achieve carbon supersaturation in the carburized layer. This plasma-carburized punch was employed in the cold, dry forging of a pure titanium wire into a flat plate while reducing the thickness by 70%. The contact interface width approached the forged workpiece width with increasing the reduction ratio. This smaller bulging deformation reveals that the workpiece is upset by homogeneous plastic flow with a lower friction coefficient. This low-friction and anti-galling forging process was sustained by an in situ solid lubrication mechanism. Unbound free carbon was isolated from the carbon-supersaturated AISI420J2 matrix and deposited as a thin tribofilm to protect the contact interface from mass transfer of metallic titanium.

XPS studies of the surface of TiO2:Ag nanopowders

n-TiO2 and n-TiO2:Ag nanopowders were synthesized by the method of electric explosion of wires (EEW). The doping of nanopowders took place during the explosion of titanium wire, on the surface of which an Ag2O layer of the appropriate mass was applied. The energy of the explosion was equal to Е = 3.1·Еs, where Es is the energy of sublimation of the metal. Based on the synthesized nanopowders, mesoporous n-TiO2 and n-TiO2:Ag films were formed. The phase composition of the surface of several series of n-TiO2 and n-TiO2:Ag samples under different annealing conditions was studied by X-ray photoelectron spectroscopy. The XPS spectra of the Ti2p- and Ag3d- levels were decomposed by the Gauss-Newton method into interconnected components 2p3/2/2p1/2 and 3d5/2/3d3/2 with parameters DЕ = 5.76 eV; I1/I2 = 0.5 and DЕ = 6.0 eV; I1/I2 = 0.66 to take into account the spin-orbit splitting of the pair respectively. The paper presents histograms of the contributions of the components to the Ti2p- and Ag3d- spectra, which vary depending on the degree of doping and annealing conditions for 4 series of samples. According to XPS data, on the surface of EEW nanopowders TiO2 and TiO2:Ag titanium is represented by Ti3+- and Ti4+- states, silver by Ag0-, Ag1+- and Ag2+- states. In all series of samples, the contribution of the Ti3+- state simultaneously increases with an increase in the absolute Ag content, which is a consequence of the lattice distortion through the formation of a surface phase with Ti–O–Ag bonds. Annealing at 300 °C in air leads to an increase in the contribution to the spectra of Ti4+- states of ЕbTi2p3/2 = 458.3 eV and Ag1+ - states. Pretreatment of the samples with hydrogen peroxide before annealing leads to an increase in the contribution of oxide-hydroxide phases of titanium and Ag0- states. Annealing of the samples at 300 °С in argon with pretreatment with hydrogen peroxide leads to an increase in the contribution to the spectra of Ti4+- states with ЕbTi2p3/2 = 458.8 eV, oxide-hydroxide phases of titanium and Ag0. It has been found that the direction of redox processes on the surface of n-TiO2 after the action of H2O2 and subsequent annealing in air depends on the state of hydration of the original nanopowders.

Protesa obturator definitif resin akrilik pada pasien systemic lupus erythematosus (SLE) pasca maksilektomi

ABSTRAKPendahuluan: Systemic lupus erythematosus (SLE) merupakan inflamasi kronis yang dapat melibatkan sistem saraf, membran mukosa, dan organ lain dalam tubuh. Avascular bone necrosis (AVN) merupakan gejala yang muncul pada penderita SLE. Maksilektomi dilakukan pada tulang maksila yang mengalami AVN. Penutupan celah pasca maksilektomi tersebut dilakukan dengan cara menggunakan protesa maksilofasial intraoral yaitu obturator. Tujuan laporan kasus ini mengkaji rehabilitasi prostetik menggunakan protesa obturator definitif resin akrilik pada penderita SLE pasca maksilektomi. Laporan kasus: Seorang wanita berusia 21 tahun datang ke Poli Gigi dan Mulut RSUP Dr. Sardjito dengan keluhan bau mulut, hilangnya gusi pada langit-langit, dan kegoyahan gigi rahang atas. Pasien didiagnosis SLE sejak lebih dari 1 tahun yang lalu. Pada pemeriksaan intraoral, selain lesi pada mukosa palatum, ditemukan juga nekrosis pada tulang palatum, kehilangan gigi 14, 15, 16, dan 25, serta kegoyahan derajat 3 pada seluruh gigi rahang atas yang tersisa. Pasien dirawat dengan obat Myfortic (2 x 180 mg/hari) dan Fluconazole (1x150 mg/hari) kemudian dirujuk ke Poli Bedah Mulut untuk dilakukan maksilektomi, dilanjutkan dengan pembuatan protesa obturator oleh tim prostodonti. Pasien dibuatkan obturator pasca bedah untuk menutup celah palatum pasca maksilektomi. Pencetakan menggunakan bahan hydrocolloid irreversible sebelum operasi untuk pembuatan obturator pasca bedah. Insersi obturator menunjukkan celah palatum tertutup rapat oleh plat akrilik. Retensi didapatkan menggunakan kawat stainless pada titanium wire mesh pengganti tulang maksila. Tidak ada keluhan saat kontrol, penelanan baik. Tiga bulan pasca pemakaian obturator pasca bedah dilakukan pemasangan obturator definitif resin akrilik rahang atas. Pemeriksaan klinis menunjukkan suara sengau berkurang, estetis, dan pengunyahan baik. Simpulan: Protesa obturator definitif resin akrilik pada pasien SLE pasca maksilektomi dapat mengembalikan fungsi estetik, mengurangi suara sengau (mengembalikan fungsi bicara), mengembalikan fungsi penelanan, dan pengunyahan.