scholarly journals Stability of Alum-Containing Paper under Alkaline Conditions

Molecules ◽  
2020 ◽  
Vol 25 (24) ◽  
pp. 5815
Author(s):  
Michal Jablonský ◽  
Jozef Šima
Keyword(s):  
Transition Metal ◽  
Alkaline Hydrolysis ◽  
Metal Species ◽  
Present Contribution ◽  
Main Mass ◽  
Paper Surface ◽  
Special Regard ◽  
Alkaline Conditions ◽  
Individual Mass ◽  
Open Issues

The present contribution evaluates the methods of degradation and stabilization of alum-containing paper with a focus on the alkaline environment achieved by deacidification procedures. In terms of reviewed subjects, the contribution focuses on alum-rosin sized paper, which is still used as a carrier of knowledge and information; however, it also mentions cellulose itself and other brands of paper. The contribution summarizes the results on the homogeneity of the distribution of alum and rosin in the paper mass and on the paper surface. It provides the knowledge gained in the field of alkaline hydrolysis and oxidation with special regard to transition metal species. It shows the values of alkaline reserves achieved in the main mass-deacidification processes. On the basis of the acquired knowledge, the contribution emphasizes the procedures of paper stabilization. Criteria of “increased mechanical permanence and lifetime prolongation” adopted to evaluate and compare the efficacy of individual mass-deacidification processes were applied and corresponding data are introduced. The contribution also draws attention to the existence of open issues in the area of paper degradation and stabilization.

Piperazine as an Inexpensive and Efficient Ligand for Pd-Catalyzed Homocoupling Reactions to Synthesize Bipyridines and Their Analogues

2019 ◽  
Vol 16 (1) ◽  
pp. 173-180
Author(s):  
Mingwei Chen ◽  
Jinyu Hu ◽  
Xiaoli Tang ◽  
Qiming Zhu
Keyword(s):  
Transition Metal ◽  
Oxidation State ◽  
Coupling Reaction ◽  
Aryl Halides ◽  
Metal Species ◽  
Good Substrate ◽  
Active Metal ◽  
Homocoupling Reaction ◽  
Catalytic Cycles ◽  
Reductive Homocoupling

Aim and Objective: The synthesis of bipyridines, especially 2, 2’-bipyridines, remains challenging because the catalytic cycle can be inhibited due to coordination of bipyridine to transition metal. Thus, the development of efficient methods for the synthesis of bipyridines is highly desirable. In the present work, we presented a promising approach for preparation of bipyridines via a Pd-catalyzed reductive homocoupling reaction with simple piperazine as a ligand. Materials and Methods: Simple and inexpensive piperazine was used as a ligand for Pd-catalyzed homocoupling reaction. The combination of Pd(OAc)2 and piperazine in dimethylformamide (DMF) was observed to form an excellent catalyst and efficiently catalyzed the homocoupling of azaarenyl halides, in which DMF was used as the solvent without excess reductants although stoichiometric reductant was generally required to generate the low-oxidation-state active metal species in the catalytic cycles. </P><P> Results: In this case, good to excellent yields of bipyridines and their (hetero) aromatic analogues were obtained in the presence of 2.5 mol% of Pd(OAc)2 and 5 mol% of piperazine, using K3PO4 as a base in DMF at 140°C. Conclusion: According to the results, piperazine as an inexpensive and efficient ligand was used in the Pd(OAc)2-catalyzed homocoupling reaction of heteroaryl and aryl halides. The coupling reaction was operationally simple and displayed good substrate compatibility.

Piecing the Puzzle Together: A Critical Review of Contemporary Research on Protest Voting

2019 ◽  
Vol 18 (4) ◽  
pp. 611-619
Author(s):  
Stefano Camatarri
Keyword(s):  
Critical Review ◽  
Future Research ◽  
State Of Health ◽  
General State ◽  
Conceptual Level ◽  
Present Contribution ◽  
Empirical Level ◽  
Political Studies ◽  
Open Issues ◽  
Do So

After several decades of debate on the so-called protest vote, the extant literature in this field is still far from consistent in conceptualization and analytical perspectives. Yet, at a time of increasing democratic stress, it becomes crucial for political studies to take stock of current research on this topic and assess its general state of health. In the light of this, aim of the present contribution is to piece together the puzzle of analytical perspectives from which scholars and pundits have approached the matter over the years. First, this article will do so at a conceptual level, disentangling different conceptualizations of protest voting. In parallel, it will do so at the technical and empirical level, categorizing both operationalization strategies and findings into alternative strands of research. As a last step, it will summarize the still open issues, organizing them within a unified platform and identifying possible lines of development for future research.

Efficient Oxygen Reduction Catalysts of Porous Carbon Nanostructures Decorated with Transition Metal Species

2019 ◽  
Vol 10 (11) ◽  
pp. 1900375 ◽  
Author(s):  
Xiaoxiao Huang ◽  
Tong Shen ◽  
Teng Zhang ◽  
Hailong Qiu ◽  
Xingxing Gu ◽  
...  
Keyword(s):  
Transition Metal ◽  
Oxygen Reduction ◽  
Porous Carbon ◽  
Carbon Nanostructures ◽  
Metal Species ◽  
Oxygen Reduction Catalysts ◽  
Reduction Catalysts

Fluoride Ion-Selective Electrode Determination of Sodium Monofluoroacetate in Meat Baits and Formulations

1984 ◽  
Vol 67 (1) ◽  
pp. 10-12
Author(s):  
George Livanos ◽  
Paul J Milham
Keyword(s):  
Alkaline Hydrolysis ◽  
Coefficient Of Variation ◽  
Steam Bath ◽  
Ion Selective Electrode ◽  
Selective Electrode ◽  
Acetone Water ◽  
Alkaline Conditions ◽  
Grade Material ◽  
Extracting Solvent

Abstract Hot aqueous alkaline conditions were used to delluorinate sodium monofluoroacetate (Compound 1080) with a mean efficiency of 98% and a coefficient of variation of 2%. The liberated fluoride was determined by ion-selective electrode. These procedures were used to analyze meat baits and commercial 1080 formulations. Compound 1080 (1–50 mg) was extracted from meat baits into 50% (v/v) acetone–water by blending, followed by ultrasonic agitation and digestion on a steam bath. The extract was filtered and the solids were agitated ultrasonically in more extracting solvent. The combined extracts were concentrated by evaporation prior to alkaline hydrolysis. This technique was well adapted to processing the large sample sizes encountered during analysis of whole baits (&lt;400 g). After correction for co-extracted inorganic fluoride, the typical recovery was 86% with a coefficient of variation &lt;7%. Proprietary 1080 formulations (&gt;90% w/w powders) were simply dissolved in water and diluted before alkaline hydrolysis. Recoveries for added reagent grade material, after correction for free fluoride, averaged 97% with a coefficient of variation 2%.

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