Behavior of Pd‐supported catalysts in phenylacetylene hydrogenation: Effect of combined use of polyvinylpyrrolidone and NaOH for magnetic support modification

2021 ◽  
Author(s):  
Alima Zharmagambetova ◽  
Eldar Talgatov ◽  
Assemgul Auyezkhanova ◽  
Nurmukhamet Tumabayev ◽  
Farida Bukharbayeva
Keyword(s):  
Supported Catalysts ◽  
Magnetic Support ◽  
Combined Use ◽  
Hydrogenation Effect

scholarly journals Efficient and selective chemical transformations under flow conditions: The combination of supported catalysts and supercritical fluids

2011 ◽  
Vol 7 ◽  
pp. 1347-1359 ◽  
Author(s):  
M Isabel Burguete ◽  
Eduardo García-Verdugo ◽  
Santiago V Luis
Keyword(s):  
Supercritical Fluids ◽  
Supported Catalysts ◽  
Chemical Transformations ◽  
Flow Conditions ◽  
Catalytic Systems ◽  
Enhanced Diffusion ◽  
Long Term Stability ◽  
Current Trends ◽  
Liquid Phases ◽  
Combined Use

This paper reviews the current trends in the combined use of supported catalytic systems, either on solid supports or in liquid phases and supercritical fluids (scFs), to develop selective and enantioselective chemical transformations under continuous and semi-continuous flow conditions. The results presented have been selected to highlight how the combined use of those two elements can contribute to: (i) Significant improvements in productivity as a result of the enhanced diffusion of substrates and reagents through the interfaces favored by the scF phase; (ii) the long term stability of the catalytic systems, which also contributes to the improvement of the final productivity, as the use of an appropriate immobilization strategy facilitates catalyst isolation and reuse; (iii) the development of highly efficient selective or, when applicable, enantioselective chemical transformations. Although the examples reported in the literature and considered in this review are currently confined to a limited number of fields, a significant development in this area can be envisaged for the near future due to the clear advantages of these systems over the conventional ones.

Coherent electron nanodiffraction from clean silver nano particles in a UHV STEM

1993 ◽  
Vol 51 ◽  
pp. 1058-1059
Author(s):  
J. Liu ◽  
M. Pan ◽  
G. E. Spinnler
Keyword(s):  
Supported Catalysts ◽  
Imaging Techniques ◽  
Nano Particles ◽  
Metal Particles ◽  
Shape Structure ◽  
Dynamical Simulations ◽  
Small Metal Particles ◽  
Extract Information

Small metal particles have peculiar chemical and physical properties as compared to bulk materials. They are especially important in catalysis since metal particles are common constituents of supported catalysts. The structural characterization of small particles is of primary importance for the understanding of structure-catalytic activity relationships. The shape and size of metal particles larger than approximately 5 nm in diameter can be determined by several imaging techniques. It is difficult, however, to deduce the shape of smaller metal particles. Coherent electron nanodiffraction (CEND) patterns from nano particles contain information about the particle size, shape, structure and defects etc. As part of an on-going program of STEM characterization of supported catalysts we report some preliminary results of CEND study of Ag nano particles, deposited in situ in a UHV STEM instrument, and compare the experimental results with full dynamical simulations in order to extract information about the shape of Ag nano particles.

Elemental Distribution in Pt-Re:Al2O3 Naphtha Reforming Catalysts

1980 ◽  
Vol 38 ◽  
pp. 200-201
Author(s):  
R. L. Freed ◽  
M. J. Kelley
Keyword(s):  
Bimetallic Catalyst ◽  
Supported Catalysts ◽  
Coke Formation ◽  
Materials Characterization ◽  
Metal Catalyst ◽  
Elemental Distribution ◽  
Exact Nature ◽  
Naphtha Reforming ◽  
Reforming Catalysts ◽  
Commercial Introduction

The commercial introduction of Pt-Re supported catalysts to replace Pt alone on Al2O3 has brought improvements to naphtha reforming. The bimetallic catalyst can be operated continuously under conditions which lead to deactivation of the single metal catalyst by coke formation. Much disagreement still exists as to the exact nature of the bimetallic catalyst at a microscopic level and how it functions in the process so successfully. The overall purpose of this study was to develop the materials characterization tools necessary to study supported catalysts. Specifically with the Pt-Re:Al2O3 catalyst, we sought to elucidate the elemental distribution on the catalyst.

Platelet monitoring for PCI

2009 ◽  
Vol 29 (04) ◽  
pp. 376-380 ◽  
Author(s):  
D. Capodanno ◽  
D. J. Angiolillo
Keyword(s):  
Interindividual Variability ◽  
State Of The Art ◽  
Coronary Intervention ◽  
Functional Tests ◽  
Treatment Regimens ◽  
Advantages And Disadvantages ◽  
Coronary Syndrome ◽  
Combined Use ◽  
Increased Risk ◽  
Percutaneous Coronary

SummaryDespite the clinical benefit associated with the combined use of aspirin and clopidogrel in patients with acute coronary syndrome or those undergoing percutaneous coronary intervention, a considerable interindividual variability in response to these drugs have been consistently reported. There is a growing interest on applying platelet functional tests with the goal of identifying patients at increased risk of recurrent ischaemic events and potentially tailoring antiplatelet treatment regimens.This manuscript will review the state of the art on the most commonly available platelet functional tests, describing their advantages and disadvantages and exploring their applicability in clinical practice.

201Tl Scintigraphy in the Evaluation of Palpable and Nonpalpable Breast Lesions: Correlation with Mammography and Ultrasonography

1997 ◽  
Vol 36 (08) ◽  
pp. 282-288 ◽  
Author(s):  
T. Atasever ◽  
A. Özdemir ◽  
I. Öznur ◽  
N. I. Karabacak ◽  
N. Gökçora ◽  
...  
Keyword(s):  
Final Diagnosis ◽  
Lower Sensitivity ◽  
Breast Lesions ◽  
Breast Cancers ◽  
Combined Use ◽  
Malignant Breast ◽  
Malignant Lesions ◽  
Benign Breast Lesions ◽  
Palpable Breast ◽  
Metastatic Sites

Summary Aim: Our goal was to determine the clinical usefulness of TI-201 to identify breast cancer in patients with suspicious breast lesions on clinical examination, and/or abnormal radiologic (mammography and/or ultrasonography) findings. Methods: TI-201 scintigraphy were performed in sixty-eight patients with 70 breast abnormalities (51 palpable, 19 nonpalpable) and compared with mammography and ultrasonography (US). Early (15 min) and late (3 h) images of the breasts were obtained following the injection of 111 MBq (3 mCi) of TI-201. Visual and semiquantitative interpretation was performed. Results: Final diagnosis confirmed 52 malignant breast lesions and 18 benign conditions. TI-201 visualized 47 of 52 (90%) overall malignant lesions. Thirty-eight of 40 (95%) palpable and 9 of 12 (75%) nonpalpable breast cancers were detected by TI-201 scintigraphy. The smallest mass lesion detected by TI-201 measured 1.5x1.0 cm. Eleven breast lesions were interpreted as indeterminate by mammography and/or sonography. TI-201 scintigraphy excluded malignancy in 7 of 8 (88%) patients with benign breast lesions interpreted as indeterminate. Five of the 18 (28%) benign breast lesions showed TI-201 uptake. None of the fibroadenoma and fibrocystic changes accumulated TI-201. TI-201 scintigraphy, mammography and ultrasonography showed 90%, 92%, 85% overall sensitivity and 72%, 56%, 61% overall specificity respectively. Twenty-one of the 28 (75%) axillary nodal metastatic sites were also detected by TI-201. In malignant and benign lesions, early and late lesion/contralateral normal side (L/N) ratios were 1.58 ± 0.38 (mean ± SD) and 1.48 ± 0.32 (p >0.05), 1.87 ± 0.65 and 1.34 ± 0.20 (p<0.05) respectively. The mean early and late L/N ratios of malignant and benign groups did not show statistical difference (p>0.05). Conclusion: Overall, TI-201 scintigraphy was the most specific of the three methods and yielded favourable results in palpable breast cancers, while it showed lower sensitivity in nonpalpable cancers and axillary metastases. Combined use of TI-201 scintigraphy with mammography and US seems to be useful in difficult cases, such as dense breasts and indeterminate breast lesions.

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