Samples of Y-Ba-Cu-O superconductor with nominal compositions of YBa2Cu3O7-d + x (weight %) Y2O3 (x = 0 - 15) were prepared by solid state reaction method using the Y2Cu2O5 and BaCuO2 precursors as the starting reagents. The X-ray diffraction (XRD) diffractograms for the doped samples (x> 0) show an additional non-superconducting Y2BaCuO5 (211) phase. The scanning electron microscope (SEM) micrographs show that the smaller Y2BaCuO5 grains are precipitated on the surface of the larger YBa2Cu3O7-d (YBCO) crystals. The grain size of the YBCO decreases with increasing yttria. The superconducting zero resistivity critical temperature (Tco) of the doped samples is very close to the Tco of the YBCO for x < 5, but it seems to be significantly decreasing for larger x. The transport critical current density (J) for x < 5 is enhanced due to magnetic flux pinning process by the 211 phase. However, Jc decreased for larger x due to the increase of weak links at the grain boundaries of the YBCO phase.
Sampel superkonduktor Y-Ba-Cu-O dengan komposisi nominal YBa2Cu3O7-d + x (% berat) Y2O3 (x = 0 -15) disediakan dengan kaedah tindakbalas keadaan pepejal menggunakan bahan pelopor Y2Cu2O5 dan BaCuO2 Difraktogram pembelauan sinar-X (XRD) bagi sampel yang didop (x > 0) menunjukkan wujudnya fasa tak mensuperkonduksi Y2BaCuO5 (211). Mikrograf mikroskop imbasan elektron (SEM) menunjukkan bahawa butiran Y2BaCuO5 yang lebih kecil itu termendap di atas permukaan hablur YBa2Cu3O7-d yang lebih besar. Saiz hablur YBCO mengecil dengan peningkatan yittria. Suhu genting kerintangan sifar (Tc) bagi sampel yang didop adalah hampir dengan Tco bagi YBCO untuk x<5, tetapi menurun dengan agak cepat untuk x yang lebih besar. Ketumpatan arus genting angkutan (J) untuk x < 5 meningkat jika dibandingkan dengan YBCO disebabkan oleh proses kepinan fluks magnet oleh fasa 211. Walau bagaimanapun, Jc menurun untuk x yang lebih tinggi kerana meningkatnya hubungan lemah pada sempadan butiran fasa YBCO.
The appearance of dental porcelains is comparable to natural teeth. This study discusses the effect of Y2O3 addition to the fluorescent property of dental porcelains. The composition of dental porcelains contained Y2O3 as the fluorescent agent and base frit. The combinations of Y2O3 added consist of a series with 0.5, 1.0, 1.5, 2.0 and 2.5 wt% respectively, based on the total composition. In the extreme condition, fluorescent agents are added from 5.0 up to 10.0 wt%. In order to enhance the fluorescent property of dental porcelains, an opacifiying agent, cerium oxide (CeO2) was also added to dental porcelains composition. The fluorescent property was determined using Spectroline EF-1400C/F that emits 240 nm wavelength ultraviolet light. The microstructure was examined by Scanning Electron Microscope (SEM). The result shows that, the fluorescent properties displayed are similar to natural teeth when subjected to ultraviolet light. SEM micrograph was able to show the fluorescent agent dispersed in glass phase. Increasing additions of Y2O3 gave the fluorescent properties near to natural teeth.
Hepatocellular carcinoma (HCC) is a malignant tumour of the hepatocyte. It is a common malignancy worldwide and causes almost half a million deaths annually. Asia is a high risk area. Although surgery (hepatectomy or liver transplantation) is the main form of curative treatment, the majority of patients are not eligible for surgery due to extent of tumour and dysfunction of liver. Radiopharmaceuticals used for transarterial treatment of HCC were Yttrium-90 microspheres, Iodine-131 lipiodol, Rhenium-188 lipiodol, and Holmium-166 Chitosan complex. Yittrium-90 microspheres are glass or resin microspheres of mean sphere diameter of 20 to 30 micrometre. The activity administered was about 4 GBq. Reported response rate was about 20%, and median survival was 54 weeks. On inoperable tumours, reported objective response of I-131 lipiodol was 40 to 70%, and median survival was six to nine months. It showed efficacy similar to TACE. In adjuvant treatment following curative resection of HCC, reported three year survival was 86% compared with 46% for the control group. The administered activity in both adjuvant and inoperable HCC was about 2 GBq (55 mCi). Rhenium-188 lipiodol is a new radioconjugate, and using it we treated 70 patients with inoperable HCC. This treatment was a part of a multi-centre trial sponsored by the International Atomic Energy Agency. Partial response was obtained in 17% of cases, while 49% had stable disease at three months, and 34% showed disease progression. In terms of survival, 19% survived one year, 60% for six months, and 90% for three months. The mean activity was about 4.6 GBq (124 mCi). This method was safe and free from adverse effects.
Tetragonal Y2O3 stabilized Zirconia (t-Y-ZrO2) powders were doped with Nb2O5 to seek a possibility if electronics doping would enhance the electronics conductivity of the insulating oxide. In this work Y2O3 was added as a stabilizer to produce tetragonal ZrO2 whereas Nb2O5 was added for the electronic doping. Several compositions of powders were prepared by thermal decomposition method and were post annealed at different temperatures. Precursor solutions were prepared from the mixture of zirconyl nitrate, yttrium nitrate and niobium tartarate as well as TEA (triethanolamine). The mixed solution were evaporated, pyrolysed and calcined to produce nanosized powders. The phase formation of the as-made powders was investigated by x-ray diffractometer. The additions of 7% Y2O3 were found to stabilize the tetragonal phase of zirconia.
The addition of Nb2O5 did not alter the stability of the tetragonal phase but it was found that the conductivity of the material has changed. The band gap as measured by the UV-Visible Spectrometer gave a value in the range of 2.97 to 5.01 eV. XRD was also used to deduce the crystallite size (by using Scherer’s equation) and transmission electron microcopy was used to view the particle sizes and shapes. The Nb doped t-Y-ZrO2 prepared in this work was to be nanosized crystal with size ranges from 7 nm to 15 nm.
The low concentration and high flow rate of air-borne butyl acetate (BA) could be effectively removed using combined adsorption-catalytic oxidation system. Ag-Y (Si/Al=80) dual-function adsorbent was investigated for the adsorption step of 1000 ppm of butyl acetate at gas hourly space velocity of 13,000 h(-1) at ambient temperature under dry and humid feeds. A central composite design (CCD) coupled with response surface methodology (RSM) was employed to obtain the optimum process conditions and the interactions between process variables were demonstrated and elucidated. Humidity and increasing organic concentration shortened the adsorption service time. The effect of moisture was more pronounced at low BA concentration. The interactions between the BA concentration and humidity were statistically significant at 95% confidence level. The optimum conditions were found to be at 4500 ppm of BA with 37 min saturation time to give 58 mg BA/g as adsorption capacity. The simulated data fitted the experimental data satisfactorily. The simulated data also correctly demonstrated the overall behaviors of the adsorption process.
The marginal fit of crowns is a concern for clinicians, and there is no conclusive evidence of any one margin configuration yielding better results than others in terms of marginal fit.
The recovery of uranium from non-conventional sources has its importance in the security of nuclear fuel supply as well as producing a more value-added product to the contaminated source. In this paper, uranium is recovered both by developing a hydrothermal process as well as using the removal method. Developing hydrothermal process involves using high uranium concentrated starting material such as xenotime and thorium hydroxide waste produced from the monazite cracking process. Oxalate separation enable to produce a better uranium and thorium separation from the yttrium in xenotime as compared to the hydroxide precipitation. Also, a solvent extraction stage was included to separate the uranium from the thorium in the process using thorium hydroxide waste. The removal method involves using selective leaching for minerals with lower uranium content such as zircon. A better removal for uranium and thorium in zircon is achieved when a heat treatment process was done prior to the leaching stage. White zircon mineral was produced after this treatment and its quality meets the requirement for white ceramic opacifier and glaze.
Aluminum substituted yttrium iron garnet nano particles with compositional variation of Y(3.0-x) A1(x)Fe5O12, where x = 0.0, 0.5, 1.0, 1.5, 2.0, 2.5 and 3.0 were prepared using sol gel technique. The X-ray diffraction results showed that the best garnet phase appeared when the sintering temperature was 800 degrees C. Nano-crystalline particles with high purity and sizes ranging from 20 to 100 nm were obtained. It was found that the aluminum substitution had resulted in a sharp fall of the d-spacing when x = 2, which we speculated is due to the preference of the aluminum atoms to the smaller tetrahedron and octahedron sites instead of the much larger dodecahedron site. High resolution transmission electron microscope (HRTEM) and electron diffraction (ED) patterns showed single crystal nanoparticles were obtained from this method. The magnetic measurement gave moderate values of initial permeability; the highest value of 5.3 was shown by sample Y3Fe5O12 at more than 100 MHz which was attributed to the morphology of the microstructure which appeared to be homogeneous. This had resulted in an easy movement of domain walls. The substitution of aluminum for yttrium is speculated to cause a cubic to rhombodedral structural change and had weakened the super-exchange interactions thus a fall of real permeability was observed. This might have created a strain in the sub-lattices and had subsequently caused a shift of resonance frequencies to more than 1.8 GHz when x > 0.5.
This is our initial response towards preparation of nano-inductors garnet for high operating frequencies strontium iron garnet (Sr3Fe5O12) denoted as SrIG and yttrium iron garnet (Y3Fe5O12) denoted as YIG. The garnet nano crystals were prepared by novel sol-gel technique. The phase and crystal structure of the prepared samples were identified by using X-ray diffraction analysis. SEM images were done to reveal the surface morphology of the samples. Raman spectra was taken for yttrium iron garnet (Y3Fe5O12). The magnetic properties of the samples namely initial permeability (micro), relative loss factor (RLF) and quality factor (Q-Factor) were done by using LCR meter. From the XRD profile, both of the Y3Fe5O12 and Sr3Fe5O12 samples showed single phase garnet and crystallization had completely occurred at 900 degrees C for the SrIG and 950 degrees C for the YIG samples. The YIG sample showed extremely low RLF value (0.0082) and high density 4.623 g/cm3. Interesting however is the high Q factor (20-60) shown by the Sr3Fe5O12 sample from 20-100 MHz. This high performance magnetic property is attributed to the homogenous and cubical-like microstructure. The YIG particles were used as magnetic feeder for EM transmitter. It was observed that YIG magnetic feeder with the EM transmitter gave 39% higher magnetic field than without YIG magnetic feeder.
The sol-gel method was carried out to synthesize nanosized Yttrium Iron Garnet (YIG). The nanomaterials with ferrite structure were heat-treated at different temperatures from 500 to 1000 °C. The phase identification, morphology and functional groups of the prepared samples were characterized by powder X-ray diffraction (PXRD), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FT-IR), respectively. The YIG ferrite nanopowder was composited with polyvinylidene fluoride (PVDF) by a solution casting method. The magnitudes of reflection and transmission coefficients of PVDF/YIG containing 6, 10 and 13% YIG, respectively, were measured using rectangular waveguide in conjunction with a microwave vector network analyzer (VNA) in X-band frequencies. The results indicate that the presence of YIG in polymer composites causes an increase in reflection coefficient and decrease in transmission coefficient of the polymer.
Triyttrium Pentairon (iii) Oxide (Y3Fe501,2) or familiar called as Yttrium Iron Garnet (YIG) is successfully prepared using a conventional mixed-oxide method of 5:3 Fe to Y ratios. YIG prepared from conventional mixed-oxide usually produced some associated phase which surely will affect electrical properties. In this study, various temperature used in the sintering process to induce associated phases (YIP) to be fully reacting to form single phase of YIG and the effect on resonance frequency is studied for resonator applications. The mixtures of oxide powders are calcined at 1100 "C and sintered at various temperatures of (1350, 1380, 1400, 1420 1450 QC, respectively). Cubic phase is detected from the formation of YIG. Some other phases such as YIP and hematite also present as secondary phase. However, it is seen that, based on the Rietvield refinement method, the total amount of secondary phase simulated are inversely proportional with sintering temperature. The powder was pressed into cylindrical pellet and tested as a microwave resonator in antenna application. It was found that, on the actual antenna circuit the operating frequencies measured are in the range of 10-12 GHz for all samples which suitable for X-band. At the end, overall radiation pattern for all samples exhibit an omnidirectional behavior.
The effects of different post-deposition annealing ambients (oxygen, argon, forming gas (95% N2 + 5% H2), and nitrogen) on radio frequency magnetron-sputtered yttrium oxide (Y2O3) films on n-type gallium nitride (GaN) substrate were studied in this work. X-ray photoelectron spectroscopy was utilized to extract the bandgap of Y2O3 and interfacial layer as well as establishing the energy band alignment of Y2O3/interfacial layer/GaN structure. Three different structures of energy band alignment were obtained, and the change of band alignment influenced leakage current density-electrical breakdown field characteristics of the samples subjected to different post-deposition annealing ambients. Of these investigated samples, ability of the sample annealed in O2 ambient to withstand the highest electric breakdown field (approximately 6.6 MV/cm) at 10-6 A/cm2 was related to the largest conduction band offset of interfacial layer/GaN (3.77 eV) and barrier height (3.72 eV).
The microstructure and mechanical properties of ceramic composites produced from alumina, yttria stabilized zirconia and chromia oxide system was investigated. The Cr2O3 weight percent was varied from 0 wt% to 1.0 wt%. Each batch of composition was mixed, uniaxially pressed to 13mm diameter and sintered at 1600 ◦C for 4 h in pressureless conditions. Studies on the effects of the sample microstructures on their mechanical and physical properties such as fracture toughness and bulk density were carried out. Results show that an addition of 0.6 wt% of Cr2O3 produces the best mechanical properties. Furthermore, microstructural observations show that the Al2O3 grain size is significantly dependent on the amount of Cr2O3 additives used. Maximum value obtained with 0.6 wt % Cr2O3 for the fracture toughness is 5.36 MPa.m1/2.
The safety and tolerability of sequential radioembolization-sorafenib therapy is unknown. An open-label, single arm, investigator-initiated Phase II study (NCT0071279) was conducted at four Asia-Pacific centers to evaluate the safety and efficacy of sequential radioembolization-sorafenib in patients with hepatocellular carcinoma (HCC) not amenable to curative therapies.
Matched MeSH terms: Yttrium Radioisotopes/therapeutic use
In this work, 10 mol% yttrium-doped ceria powders, Ce0.9Y0.1O1.95, were synthesised using a new mechanical technique, mechanochemical reaction, in which both impact action and shearing forces were applied for efficient fine grinding, subsequently leading to higher homogeneity of the resultant powders. Ce0.9Y0.1O1.95 prepared using this new technique was systematically compared with a sample of the same prepared using conventional solid-state methodology. X-ray diffraction analysis showed all prepared samples were single phase with a cubic fluorite structure. Generally, Y2O3-doped CeO2 electrolytes prepared by mechanochemical reactions were stable at a lower temperature (1100 °C) compared with a sample of the same synthesised using the conventional solid-state method. Characterisations using differential thermal analysis (DTA) and thermogravimetric analysis (TGA) showed no thermal changes and phase transitions, indicating all materials were thermally stable. The electrical properties of the samples investigated by AC impedance spectroscopy in the temperature range 200–800 ˚C are presented and discussed. Scanning electron microscopy (SEM) was used to study the morphology of the materials. Fine-grained powders with uniform grain-size distribution were obtained from the mechanochemical reaction.
Micro powder injection molding (vim) is a promising process that may satisfy the demand on miniaturization parts to micro domain in mass production with low manufacturing cost. Three mol% yttria stabilized zirconia (Ysz) with nano-sized powder and binder system consists of polyethylene glycol (PEG), polymethyl methacrylate (PMMA) and stearic acid (sA) were used. Nano-size powders with higher surface area generally require more binder to form a feedstock. As such, determination of the optimum powder loading of the feedstock for 1UPIM process is important. The rheological characteristics of different YSZ feedstocks with powder loading of 52 53 and 54 vol.% were investigated in terms of flow behavior as a function of viscosity and shear rate. Fairly low values of flow behavior exponent ranging from 025 to 0.39 (n<1) resulted in pseudoplastic flow behavior of the examined Yszfeedstock. The 52 vol.% feedstock exhibited the lowest viscosity resulting in highest activation energy and lowest moldability index of 1.862x10-6, while the 54 vol.% feedstock regardless to its high viscosity, yielded a low activation energy of 4.14 kJImol and high moldability index of 4.59x10-6. Based on rheological properties obtained, a powder loading of 54 vol.% has desirable feedstock characteristics for iumm process and exhibited molding ability for micro detail filling. The relationship between the optimum rheological properties obtained and the actual injection process was also determined. The results showed that the green parts were able to be injected without defects such as short shot or flashing.
Samarium-153 (153Sm) styrene divinylbenzene microparticles were developed as a surrogate for Yttrium-90 (90Y) microspheres in liver radioembolization therapy. Unlike the pure beta emitter 90Y, 153Sm possess both therapeutic beta and diagnostic gamma radiations, making it possible for post-procedure imaging following therapy.
Matched MeSH terms: Yttrium Radioisotopes/therapeutic use
This study utilizes the technique of self-assembly to fabricate arrays of nanoislands on (001)-oriented yttria-stabilized zirconia single crystal substrates with miscut of 10° toward <110> direction. These self-assembled nanostructures were annealed at 1100°C for 5h upon doping with 10mol% gadolinium-doped ceria (GDC) by powder-suspension based method. X-Ray diffraction result showed that the miscut substrate after doping GDC was in the cubic phase. Energy dispersive X-ray (EDX) illustrates that the nanopatterned material contains all the elements from the GDC source and yttria-stabilized zirconia (YSZ) substrate. It also demonstrates a higher surface roughness and a more hydrophilic surface. The nanostructured materials were subsequently used for an in vitro study using a human fetal osteoblastic cell line (hFOB). An improved spreading, enhanced cell proliferation and up-regulated alkaline phosphatase activity (ALP) were observed on the nanopatterned substrates compared to the control substrates. Calcium deposits, which were stained positively by Alizarin Red S, appeared to be more abundant on the nanopatterned surfaces on day 7. The overall findings suggest that post fabrication treatment with surface modification such as creating a nanostructure (e.g. nanopatterns) can improve biocompatibility.
We aimed to investigate the validity of the partition model (PM) in estimating the absorbed doses to liver tumour ([Formula: see text]), normal liver tissue ([Formula: see text]) and lungs ([Formula: see text]), when cross-fire irradiations between these compartments are being considered. MIRD-5 phantom incorporated with various treatment parameters, i.e. tumour involvement (TI), tumour-to-normal liver uptake ratio (T/N) and lung shunting (LS), were simulated using the Geant4 Monte Carlo (MC) toolkit. 108track histories were generated for each combination of the three parameters to obtain the absorbed dose per activity uptake in each compartment ([Formula: see text], [Formula: see text], and [Formula: see text]). The administered activities, A were estimated using PM, so as to achieve either limiting doses to normal liver, [Formula: see text] or lungs, [Formula: see text] (70 or 30 Gy, respectively). Using these administered activities, the activity uptake in each compartment ([Formula: see text], [Formula: see text], and [Formula: see text]) was estimated and multiplied with the absorbed dose per activity uptake attained using the MC simulations, to obtain the actual dose received by each compartment. PM overestimated [Formula: see text] by 11.7% in all cases, due to the escaped particles from the lungs. [Formula: see text] and [Formula: see text] by MC were largely affected by T/N, which were not considered by PM due to cross-fire exclusion at the tumour-normal liver boundary. These have resulted in the overestimation of [Formula: see text] by up to 8% and underestimation of [Formula: see text] by as high as -78%, by PM. When [Formula: see text] was estimated via PM, the MC simulations showed significantly higher [Formula: see text] for cases with higher T/N, and LS ⩽ 10%. All [Formula: see text] and [Formula: see text] by MC were overestimated by PM, thus [Formula: see text] were never exceeded. PM leads to inaccurate dose estimations due to the exclusion of cross-fire irradiation, i.e. between the tumour and normal liver tissue. Caution should be taken for cases with higher TI and T/N, and lower LS, as they contribute to major underestimation of [Formula: see text]. For [Formula: see text], a different correction factor for dose calculation may be used for improved accuracy.
Purpose Selective internal radiation therapy or radioembolization (RE) shows efficacy in unresectable hepatocellular carcinoma (HCC) limited to the liver. This study compared the safety and efficacy of RE and sorafenib in patients with locally advanced HCC. Patients and Methods SIRveNIB (selective internal radiation therapy v sorafenib), an open-label, investigator-initiated, phase III trial, compared yttrium-90 (90Y) resin microspheres RE with sorafenib 800 mg/d in patients with locally advanced HCC in a two-tailed study designed for superiority/detriment. Patients were randomly assigned 1:1 and stratified by center and presence of portal vein thrombosis. Primary end point was overall survival (OS). Efficacy analyses were performed in the intention-to-treat population and safety analyses in the treated population. Results A total of 360 patients were randomly assigned (RE, 182; sorafenib, 178) from 11 countries in the Asia-Pacific region. In the RE and sorafenib groups, 28.6% and 9.0%, respectively, failed to receive assigned therapy without significant cross-over to either group. Median OS was 8.8 and 10.0 months with RE and sorafenib, respectively (hazard ratio, 1.1; 95% CI, 0.9 to 1.4; P = .36). A total of 1,468 treatment-emergent adverse events (AEs) were reported (RE, 437; sorafenib, 1,031). Significantly fewer patients in the RE than sorafenib group had grade ≥ 3 AEs (36 of 130 [27.7%]) v 82 of 162 [50.6%]; P < .001). The most common grade ≥ 3 AEs were ascites (five of 130 [3.8%] v four of 162 [2.5%] patients), abdominal pain (three [2.3%] v two [1.2%] patients), anemia (zero v four [2.5%] patients), and radiation hepatitis (two [1.5%] v zero [0%] patients). Fewer patients in the RE group (27 of 130 [20.8%]) than in the sorafenib group (57 of 162 [35.2%]) had serious AEs. Conclusion In patients with locally advanced HCC, OS did not differ significantly between RE and sorafenib. The improved toxicity profile of RE may inform treatment choice in selected patients.