Addition Of Platinum Research Articles

Chemotherapy for advanced ovarian cancer. Advanced Ovarian Cancer Trialists Group.

Ovarian carcinoma is the seventh most common cancer of women in the world and is responsible for the greatest number of deaths from gynaecological malignancy in Europe and North America. Although many studies have explored the use of chemotherapy in this disease, most individual trials have been too small to show clear benefit of one type of chemotherapy over another. The type and intensity of chemotherapy used routinely for women with advanced ovarian cancer has varied because of uncertainty about the effectiveness of the different regimens. The objective of this review was to compare single drugs versus combinations of drugs, platinum versus non-platinum, and carboplatin versus cisplatin-based chemotherapy in women with advanced ovarian cancer. Search strategy: We searched MEDLINE, and CancerLit bibliographic databases and the National Cancer Institute and the UK Co-ordinating Committee on Cancer Research registers of trials. We also handsearched the proceedings of meetings and contacted experts in the field and drug companies. Randomised trials of: (1) single non-platinum versus non-platinum combination chemotherapy (2) single non-platinum versus platinum combination chemotherapy (3) non-platinum regimen versus the same regimen plus cisplatin (4) single platinum versus platinum combination chemotherapy (5) cisplatin versus carboplatin-based chemotherapy in women with advanced ovarian cancer. Individual patient data were obtained from the trial investigators, checked by the reviewers and finally verified by the trial investigator. Main results: 49 trials involving 8763 women were included. The data were combined to calculate hazard ratios (HR) for survival on an intention-to-treat basis. For single non-platinum versus platinum combination chemotherapy the overall HR for survival was 0.93, 95% confidence interval (CI) 0.83-1.05 in favour of platinum-based combination chemotherapy. For non-platinum regimens compared with the same regimen plus cisplatin the survival HR was 0.88, 95% CI 0.79- 0.98 in favour of the addition of platinum to drug regimens. Single platinum compared with platinum combination therapy gave a HR of 0.91, 95% CI 0.79-1.05 in favour of combination chemotherapy. Cisplatin versus carboplatin gave a HR of 1.02, 95% CI 0.93-1.12. Sub-group analyses for age, stage, grade, histology, resection, bulk of residual tumour and performance status were undertaken for cisplatin versus carboplatin only. No difference in effect was found. The available evidence, although not conclusive, suggests that platinum-based chemotherapy is better than non-platinum therapy. There is some evidence that combination therapy improves survival compared with platinum alone. No difference in effect has been shown between cisplatin and carboplatin.

Partial oxidation of methane to synthesis gas over α-Al2O3-supported bimetallic Pt–Co catalysts

The partial oxidation of methane to synthesis gas was studied at atmospheric pressure and in the temperature range of 550–800°C over α-Al2O3-supported bimetallic Pt–Co, and monometallic Pt and Co catalysts, respectively. Both methane conversion and CO selectivity over a bimetallic Pt0.5Co1 catalyst were higher than those over monometallic Pt0.5 and Co1 catalysts. Furthermore, the addition of platinum in Pt–Co bimetallic catalysts effectively improved their resistance to carbon deposition with no coking occurring on Pt0.5Co1 during 80 h reaction. The FTIR study of CO adsorption observed only linearly bonded CO on bimetallic Pt–Co catalysts. TPR and XPS showed enhanced formation of a cobalt surface phase (CSP) in bimetallic Pt–Co catalysts. The origins of the good coking resistivity of bimetallic Pt–Co catalysts were discussed.

The effect of platinum additions on the oxidation of directionally-solidified Ni-Cr-Al-Y-Cr3C2 alloys at 1,100 and 1,200°C

The effects of 2wt% platinum addition on the oxidation behaviour of directionally-solidified, yttrium-containing Ni-Cr-Al-Cr3C2 alloys (Ni-12.3Cr-6.9Al-1.8C-0.2Y in wt%) at 1,100° and 1,200°C in oxygen have been investigated under isothermal and thermal cycling conditions. Owing to the presence of yttrium, aluminium oxidized externally rather than internally at both temperatures. At 1,100°C, the addition of platinum apparently favoured the formation of a continuous Al2O3 scale over primary carbides intersecting the alloy surface. The scale remained substantially adherent after isothermal oxidation, but lifted and cracked on thermal cycling, though it did not spall significantly. Overdoping with yttrium (0.7 wt%Y) had a detrimental effect on the scale adherence, probably because it altered the homogeneity of the platinum distribution by forming Pt-Y intermetallics. At 1,200°C, an external Al2O3 scale formed initially, but spalled extensively after short times under both isothermal and thermal cycling conditions. During cyclic oxidation, re-formation of an aluminium scale was possible until a critical level of aluminium depletion in the alloy was reached, with the less protective oxides forming during the subsequent oxidation cycles. The inherent lack of ductility of the Al2O3 scale over the carbide particles, coupled with the CrO3 vaporization at high temperatures, could account for the observations.

Formation and Stability of NI(PT) Silicide on (100)SI and (111)SI

AbstractThe effect of a small amount of Pt (5 at.%) on the thermal stability of NiSi film on (100)Si and (111 )Si has been investigated. Rutherford back scattering, Scanning Electron Microscopy, and X-ray diffraction have been used to study the formation, microstructure and orientation of the silicide. The addition of platinum results in increasing the disilicide nucleation temperature to 900°C and thus leads to a better stability of NiSi at high IC processing temperatures. The presence of Pt also induced a texture of the NiSi film both on (11 1)Si and (100)Si. The increase in thermal stability is explained in terms of nucleation controlled reaction concept and should open new possibilities for the use of NiSi in self aligned silicidation. The redistribution of Pt in the silicide is examined and explained in terms of kinetics and thermodynamics considerations. The addition of Pt also increases the temperature of agglomeration of NiSi.

Effect of platinum addition on the microstructure and critical current density in (Nd, Eu, Gd)-Ba-Cu-O

We have studied the microstructure and magnetic properties of oxygen-controlled-melt-growth (OCMG) processed (Nd, Eu, Gd)-Ba-Cu-O superconductors, which contain about 40 mol% of (NEG211) second phase by varying the amount of Pt from 0.25 to 3 mol%. Scanning electron and transmission electron microscopic observations demonstrate that 0.5 mol% Pt is the optimum quantity to refine the 211 particles, leading to a dramatic increase in the critical current density. An addition of 2-3 mol% Pt results in the formation of relatively large NEG211 particles. values increase with increasing Pt content up to 0.5 mol% and then decrease thereafter. A high critical current density of 70 000 A at T = 77 K and an applied field of 2.2 T ( axis) is achieved in the sample with 0.5 mol% Pt. Our results demonstrate that the Pt addition is critical to the refinement of the 211 particle size and thus for the enhancement of the critical current density.

Microstructure and pinning in high- and large- (Nd, Eu, Gd)-123 superconductors prepared by OCMG process

The effects of (NEG-211), Pt and additions on OCMG-processed (`NEG') composites have been investigated in detail using a combination of scanning electron microscopy and measurements of critical current densities, . Microstructural observations clearly indicated that the platinum addition was effective in refining the NEG-211 secondary-phase particles, which led to a dramatic increase in in the low-field as well as in the high-field region. TEM-EDX analyses revealed that the small secondary-phase particles (diameter ) consist mainly of Gd in the rare earth site, while the large particles contain Nd, Eu and Gd in the rare earth site with an even ratio, which is identical to the nominal composition of the precursor powder. For an NEG sample with 40 mol% NEG-211 additions, a large critical current density of 60 000 A at 77 K was observed in a magnetic field of 3 T applied parallel to the c-axis of the sample. The critical current density measurements showed that the zero field and peak values are similar in samples with 30 and 40 mol% of NEG-211 added. In contrast to this, the combination of and Pt addition was not as effective in refining the NEG-211 particles, and also the values were found to decrease in the entire field region.

Effect of Co, Pt, and Au additions on the stability and epitaxy of NiSi2 films on (111)Si

We studied the effect of the addition of cobalt, platinum, or gold on the cell parameter of NiSi2 deposited epitaxially on (111)Si. Namely, the formation and the microstructure of NiSi2 films containing one of these elements are compared to those of the pure disilicide. The solubility of Co, Pt, and Au in NiSi2 ranges from a total substitution to nickel in the case of cobalt to a very weak quantity (less than 1%) in the case of platinum. An intermediate behavior was observed for gold which can occupy more than 10% of the metal sites. This important solubility has been confirmed by analysis of bulk Ni(Au) disilicides and is understood as a consequence of the metastability of gold silicides. Cobalt, Pt, and Au additions change the temperature of formation of NiSi2: from 800 °C for reaction with pure nickel, this temperature is lowered to 650 °C by Co and Au additions while it is increased to 950 °C for Pt. These modifications are consistent with the nucleation controlled formation of NiSi2 and the effect of added elements on both the interfacial energy and the stability of the disilicide. Measurements of the cell parameters (perpendicular and parallel) by x-ray diffraction revealed the relaxation state and the cell evolution of NiSi2 films. Platinum addition does not modify the cell in agreement with a very weak incorporation of platinum in NiSi2. The rigid interface model is well adapted to the growth of NiSi2, Ni(Au)Si2, and Ni(Co)Si2 films. According to this model and in spite of a large rhombohedral deformation, the system which better accommodates silicon is Ni(Co)Si2: in this case, there is practically no misfit between the film and the substrate. We also showed that misfit dislocations are generated principally during the NiSi2 formation and that their density evolves very little afterwards.

Fabrication and characterisation of large-grain YBa 2Cu 3O 7 superconductors by seeded melt texturing

In this work, we investigate the fabrication and characterisation of YBCO single grain monoliths using a seeding melt growth technique. It was found that there exits a narrow temperature–composition window for the stable growth of single grain monoliths. Addition of platinum has the beneficial role of refining the Y211 particles size while remaining inert to Y123 matrix by forming a Pt-containing secondary phase. Pellets of diameter up to 3 cm were fabricated under isothermal slow cooling condition. Neutron scattering and field mapping show their single grain nature, in spite of the existence of low-angle grain boundaries and slightly misoriented grains. Small size samples exhibit high critical current densities, either from magnetic measurement or from direct transport measurement, while J c are reduced three- to four- fold in large bulk pellets. It is believed that main limitations for levitation forces in these pellets are oxygen inhomogeneities and cracks due to oxygen diffusion induced stresses.

Magnetic field dependence of critical current density in Pt-doped thick films

The addition of platinum and the (0412) phase to melt-textured (YBCO) thick films has been shown to induce notable improvements in the flux pinning characteristics of the material. Transport critical current density values in excess of at 77 K and self-field have been achieved, with volume magnetization values in excess of at 77 K and zero applied field. Measurements of both the inter- and the intra-granular flux pinning characteristics in applied fields indicate that this behaviour is greatly improved in the Pt-doped YBCO films. The enhanced flux pinning was attributed to an increase in defect densities within the matrix material, associated with a change in the morphology of inclusions.

The Transformations of n-Butane over Platinum-Promoted Mn-Aluminophosphate Molecular Sieves

The catalytic transformations of n-butane were performed over a platinum-promoted manganese-substituted aluminophosphate molecular sieve (Pt/MnAPO-11), and over a Pt promoted manganese-supported aluminophosphate molecular sieve (Pt/Mn/AlPO4-11). For comparison purposes, the reactions were also carried out over a Pt-supported AlPO4-11 molecular sieve (Pt/AlPO4-11). X-ray diffraction (XRD) was used to determine the crystallographic structure of the unpromoted and Pt-promoted samples. Phosphorous 31-magic angle spinning-nuclear magnetic resonance (31P MAS NMR) spectroscopy was used to study the possible31P–Mn(II) dipolar interaction. Brönsted and Lewis acidity were measured by pyridine chemisorption at different temperatures. Pt dispersions were determined by hydrogen chemisorption. CO chemisorption followed by IR spectroscopy was used to corroborate the dispersion measurements and to evaluate possible changes in the electronic density of the Pt phase. The catalytic results indicate higher yields (and selectivities) for the production of isobutane and isobutene over the Pt/MnAPO-11, compared with those observed over the Pt/Mn/AlPO4-11 and Pt/AlPO4-11 samples. Also, a severe decrease in the yield, in the selectivity and in the turnover frequency (TOF), for the formation of hydrocarbons with less than four carbon atoms, was observed for the Pt/MnAPO-11 system when compared with the Pt/Mn/AlPO4-11 and Pt/AlPO4-11 solids. A larger number of (moderate+strong) Brönsted acid sites was found for the MnAPO-11 solid compared to the Mn/AlPO4-11 and AlPO4-11 samples. For the last two solids, no Brönsted acidity was detected after evacuation of the catalyst at 623 K.31P MAS NMR results showed an increase in the intensity of the side bands, probably due to an anisotropic paramagnetic shift caused by a stronger dipolar interaction between the31P and the paramagnetic Mn(II) ions on the MnAPO-11 sample, when compared with the Mn/AlPO4-11 solid. These results suggest a better dispersion of the manganese species on the MnAPO-11 solid, which would facilitate the above mentioned31P–Mn(II) interaction. The addition of platinum decreased the Lewis and Brönsted acidity for all the catalysts studied. The Pt dispersions were 68%, 59%, 49% for the Pt/AlPO4-11, for the Pt/Mn/AlPO4-11 and for the Pt/MnAPO-11 solids, respectively. The constant value obtained for the IR CO–Pt stretching frequency (Pt/AlPO4-11 and Pt/MnAPO-11 samples) (ca 2067 cm−1), as well as the drop in the Pt dispersion observed for the manganese containing solids, suggest an ensemble effect as responsible for the differences observed in the yield, selectivity, and TOF of formation of hydrocarbons with <C4. The higher yield and selectivity observed for the formation of iso-C4 and iso-C4=hydrocarbons over the Pt/MnAPO-11 solid, were accounted for in terms of the largest number of (moderate+strong) Brönsted acid sites found on this solid. The catalytic and characterization results suggest the incorporation of manganese into the molecular sieve structure, for the Pt/MnAPO-11 sample.

Helix-Coil Transitions in DNA by Novel Pt(II) Complexes: A pH Melting Study

Recent reports have shown that pH could also be used as a melting factor to monitor helix- coil transitions in DNA; the results being comparable to those obtained by Tm studies. The rapidity with which the method can be performed to obtain similar transition curves, and elimination of the evaporation factor (at high temperatures as seen in Tm studies) is one of the advantages offered by this technique. With regard to its suitability in studying DNA-drug interactions, the addition of platinum (II) complexes changed the Pm (pH of melting) in a predictable manner thereby confirming the destabilization of bases in DNA. In the present study, melting profiles of calf thymus DNA modified by certain chloro substituted platinum complexes have been generated using pH as a denaturing factor. These novel platinum complexes have been recently shown to have potential tumour inhibiting properties too. Diammine diaqua platinum (active form of the anti tumour drug cisplatin) was coupled to β poly-L-malate (a bioresorbable polymer synthesized by a myxomycete), L- malate and L-succinate. At a constant Pt:P ratio (0.2), the extent of damage to DNA by these complexes in comparison to cisplatin was cisPt>SuccPt>MalPt>PMA-Pt>carboplatin. Given the similarity of the side groups of these platinum compounds with that of carboplatin (a successful second generation analog of cisplatin), interesting variations have been obtained in the DNA melting profiles, the implications of which have been discussed in the present study.

Preparation and characterization of melt textured NdBa2Cu3O7−δbulk superconducting ceramics

NdBaCuO superconductors have been textured by the oxygen controlled melt growth method. The addition of platinum or Nd422 does not refine the 422 phase, but the latter improves the microstructural quality. High purity precursors are necessary to achieve high T c and J c (up to 56 000 A/cm 2 ). The flux pinning mechanisms are discussed in terms of oxygen deficiency, Nd-Ba substitution and softening of the vortex lattice.

Fractal dimension of grain boundary in CuAu alloys refined by platinum addition

Irregularity of the grain boundaries in CuAu alloys refined by platinum addition was estimated by fractal analysis. The fractal dimension increased with decreasing the grain size, which introduced by platinum addition. The grain refinement produced more complexity in microstructure.

Skeletal Isomerization of n-Butane Over Mordeniteand Beta Zeolites

It was found that the addition of platinum (3 wt.%) substantially increases the total n-butane conversion and selectivity to isobutane over H-Beta zeolite. The same holds for H-Mordenite; however, the conversion significantly decreases in time at 350 °C due to the coking of the catalyst. The selectivity to isobutane is the highest at 300 °C over both zeolite types with platinum (over Pt/H-Beta 1.8 times higher than over Pt/H-Mordenite at almost the same conversion levels of 30 and 36%, respectively). The H-forms of both zeolite types are most selective at 250 °C, but the total conversion is low. The results obtained are related to the structural features of both zeolite types.

Improvement of critical current density in YBaCuFO compounds by addition of platinum

Platinum added YBaCuFO compounds with nominal composition YBa 2Cu 3F 0.4O xPt y { y=0, 0.3, 0.5} were prepared by a partial melt process performed at lower temperature than the conventional melt process. Optical micrograph observations showed that Y 2BaCuO 5 (211) particles increase in density and are dispersed finely when increasing the doping of Pt up to 0.3 wt%. For the 0.5 wt% Pt sample, however, the size of the 211 particles became larger than in the samples containing less than 0.3 wt% Pt. The magnetization was measured using a SQUID magnetometer in the temperature range 20–77 K under magnetic fields B e up to 1 T. The magnetization M also increased with increasing quantity of platinum up to 0.3 wt%. The J c values estimated from the width of the magnetization curves were 9.8×10 7 A/m 2 for the 0.3 wt% Pt sample and 5.4×107 A/m 2 for the undoped sample at 77 K and B e=0.8 T. In addition, the whereabouts of the platinum in the quenched samples was investigated by using electron spectroscopy for chemical analysis (ESCA).

The effect of platinum additions on precipitation and coarsening during melt texturing of

By studying the behaviour of (Y-123) pellets coated with (0412) the effect of Pt additions on various stages of (211) development can be discerned. It is observed that the 0412 compound is readily dissolved in the peritectic melt. Pt in solution promotes nucleation of 211 by decreasing the critical nucleus radius. Pt also reduces the 211 coarsening rate by decreasing the 211/liquid interfacial energy.

Reactions of Carboxylic Acids on Oxides: 1. Selective Hydrogenation of Acetic Acid to Acetaldehyde

Acetic acid has been used as a model compound in the selective hydrogenation of aliphatic acids, which contain α-hydrogen atoms, to their corresponding aldehydes. In contrast to what the literature predicts, it appeared to be possible to produce acetaldehyde directly from acetic acid. The appropriate catalyst consists of an oxide with an intermediate metal–oxygen bond strength. Addition of platinum to the catalyst enhances selectivity and activity. A mechanism is proposed, based on the involvement of lattice oxygen (viz., a Mars and Van Krevelen mechanism) and the spill-over of activated hydrogen from the platinum to the oxide. The most important side reaction is the formation of acetone from two molecules of acetic acid (ketonization), but this reaction is suppressed completely by the addition of platinum to the catalyst.

Catalytic combustion of diesel soot over metal oxide catalysts

The activity of different metal oxides in the catalytic combustion of a diesel soot having a high amount of adsorbed hydrocarbons has been investigated and tested in a TPO apparatus. Two different steps have been observed. The first is related to the combustion of hydrocarbons adsorbed on soot and the second one to the combustion of the graphitic solid fraction. A high surface area Fe 2O 3 was found to be the most active catalyst for the oxidation of hydrocarbons, whereas V 2O 5 was also able to promote the combustion of graphitic carbon. The oxidation of the hydrocarbon fraction has been correlated with the surface area and the strength of the metal-oxygen bond of the metal oxide. The combustion of graphitic carbon is favoured instead on metal oxides having a low melting point. The effect of platinum addition to γ-alumina has been also investigated. Spillover of activated oxygen from Pt to the support has been postulated to take into account the promotion of the oxidation of graphitic carbon.

Effects of second phase and platinum additions on the microstructure and the critical current density of OCMG processed (Nd, Eu, Gd)–Ba–Cu–O

Abstract We have investigated the effects of second phase (Nd, Eu, Gd) 2 BaCuO 5 (NEG211) and platinum addition on the superconducting properties for (Nd, Eu, Gd)Ba 2 Cu 3 O Y (NEG123) composite prepared by the oxygen–controlled melt–growth (OCMG) process. The addition of NEG211 slightly decreased the critical temperature ( T c ) and increased the critical current density ( J c ), particularly in a low field region. The secondary peak effect, which is commonly observed in OCMG processed Nd123, was reduced with the NEG211 addition of >10%. Refinement of the NEG211 second phase was achieved by Pt addition, which led to a dramatic increase in both J c values and the irreversibility field. Low field J c varied as V f / d , where V f is the volume fraction and d is the mean diameter of NEG211, supporting the idea that the 211/123 matrix is responsible for the pinning-like melt–processed Y–Ba–Cu–O. However, in a high field region, due to the presence of additional pinning by field–induced pinning centers, such a relationship is not observed. Our results suggests that fine distribution of the second phase is effective in improving pinning properties in the (Nd, Eu, Gd)–Ba–Cu–O composite.

Electron paramagnetic resonance spectroscopy study of the adsorption of O 2 and CO on a Pt/CeO 2/Al 2O 3 catalyst

O 2 adsorption and CO interaction with previously generated superoxide radicals on a Pt/CeO 2/Al 2O 3 catalyst preoutgassed at different temperatures ( T v) have been studied by electron paramagnetic resonance spectroscopy. The results show the formation, upon oxygen adsorption, of several types of superoxide species bonded to surface cerium ions. Comparison of the characteristics of the different superoxide species with those observed on the CeO 2 Al 2O 3 support shows that, although some adsorption sites can be removed by the addition of platinum, the presence of the latter favors the formation of specific types of anion vacancies at the ceria-alumina interface. The reactivity of the superoxide radicals towards CO is enhanced by the presence of platinum, suggesting that at least a part of the platinum is located in positions close to the sites (near the ceria-alumina boundary) where these radicals are adsorbed.