Sustainability of mass deacidification of library objects

In Bibliotheken und Archiven wurden Bücher, die infolge ihrer Acidität gefährdet waren, mit Massenentsäuerung behandelt. Obwohl diese Behandlung auf Grundlage umfangreicher Forschung und Tests angewendet wurde, wurde die Nachhaltigkeit der Massenentsäuerung aufgrund mangelnder Qualitätskontrollen und der Gefahr einer alkalischen Behandlung auf die originalen Bücher, die bis zu 150 Jahre natürlich gealtert waren, in Frage gestellt. Die Ziele der vorliegenden Studie waren nicht nur die Beurteilung der Leistungsfähigkeit von Massenentsäuerungprozessen in den letzten zwei Jahrzehnten, sondern auch die Untersuchung des Einflusses von Massenentsäuerung auf molekularer Ebene von Cellulose, fokussiert auf ß-Eliminierung ausgelöst durch Alkali. Über 400 Bücher aus Bibliotheken wurden analysiert. Es wurde der pH-Wert und die alkalische Reserve für ausgewählte Originalbücher gemessen, sowie Röntgenfluoreszenz-Spektroskopie (XRF) und Rasterelektronenmikroskopie (REM-EDX) angewendet. Fünfundzwanzig entsäuerte und ihre identen nichtentsäuerten Bücher wurden durch Gelpermeationschromatographie (GPC) mit Fluoreszenz- und Laserlichtstreudetektion nach Fluoreszenzmarkierung von Carbonylgruppen analysiert, wodurch eine besserer Einblick in den Degradationsmechanismus von entsäuerten Papieren, vor und nach beschleunigter Alterung, möglich war. ß-Eliminierung, ausgelöst durch Keto-/Aldehyd-Gruppen entlang der Cellulosekette, scheint unvermeidlich, sowohl nach Massenentsäuerung als auch während beschleunigter Alterung. Doch dank der charakteristischen Verteilung der Carbonylgruppen in natürlich gealtertem Papier verringertdie Kettenspaltungdurch ß- Eliminierungdas Molekulargewicht nicht in großem Ausmaß. Das wurde im Rahmen dieser Studie durchbeschleunigte Alterung aufgezeigt. Der Abbau bei entsäuertem Originalpapier wurde durch die Vorteile der alkalischen Reserve aufgehoben,die saure Hydrolyse in bemerkenswertem Ausmaß reduziert, ohne stark durch ß-Eliminierung betroffen zu sein.Mass deacidification treatment has been applied to books, in the libraries and archives, that were in jeopardy due to their acidity. Sustainability of mass deacidification was questioned due to lack of quality control systems and a risk of alkaline treatment to the original books, which have naturally aged for up to 150 years. In the present study, the aims were not only the assessment of the performance of mass deacidification processes, but also the study of the influence of mass deacidification on a molecular level of cellulose, focusing on ß- elimination triggered by alkali. Over 400 books from the German Libraries were analyzed. Surface pH and alkaline reserve was determined for selected original books by different methods. Twenty-five deacidified books and their identical non-deacidified papers were analyzed by GPC coupled with fluorescence and light scattering detectors after fluorescence labeling of carbonyl groups, which offered deeper insights into degradation mechanisms. ß-elimination triggered by keto/aldehyde groups along the cellulose chain seems to be unavoidable after mass deacidification as well as during accelerated aging. However, thanks to the characteristic distribution of carbonyl groups found in naturally aged book paper, ß-elimination did not cause severe chain scission to an extent that lowered the molecular weight. The study of accelerated aging added to this finding. Degradation of original deacidified paper was overruled by the benefits from alkaline reserve, reducing acid hydrolysis remarkably, without being affected severely by ß-elimination. Degradation of cellulose after accelerated aging did not correlate with the initial carbonyl group content prior to accelerated aging or to the lowered content of along-chain carbonyls after accelerated aging, which is a sign of ß-elimination. Therefore, a threat of alkaline degradation under conditions of the mass deacidification tested was minor.submitted by: Kyujin AhnZsfassung in dt. SpracheWien, Univ. für Bodenkultur, Diss., 2013OeBB(VLID)193153

Acetylation of cellulose – Another pathway of natural cellulose aging during library storage of books and papers

Gaseous acetic acid is formed under conditions of storage of historic paper objects. Its presence not only promotes hydrolytic cleavage of cellulose, but also causes acetylation of the cellulosic material to very small degree. The acetylation reaction proceeds under ambient conditions and without catalyst. Different analytical methods were used to prove the presence of organic acetates on cellulosic paper matrices. DESI-MS in combination with 2H-isotopic labeling showed the presence of sugar fragments with different acetylation patterns. A method based on Zemplen saponification was applied and worked also in the presence of a large excess of acetic acid and/or inorganic acetates. The acetylation effect was quantified for model papers and original, naturally aged paper samples. While cellulose acetylation was clearly proven to be another general pathway of paper aging, further studies of this acetylation phenomenon are needed with regard to conservational aspects and suitable paper storage conditions

Spectroscopic study of the radionuclide Na-21 for the astrophysical F-17(alpha, p)Ne-20 reaction rate

The Mg-24(p,alpha)Na-21 reaction was measured at the Holifield Radioactive Ion Beam Facility of the Oak Ridge National Laboratory to study the spectroscopy of the radionuclide Na-21. A 31-MeV proton beam from the 25 MV tandem accelerator bombarded isotopically enriched Mg-24 targets. Recoiling He-4 particles were identified by an annular silicon strip detector array. Two energy levels at E-x = 6.594 and 7.132 MeV were observed for the first time. By comparing the experimentally obtained angular distributions and distorted wave Born approximation calculations, the spins and parities of Na-21 energy levels were constrained. The astrophysicallyi-mportant F-17(alpha, p)Ne-20 reaction rate was also calculated for the first time using resonance parameters for 12 energy levels

Spin assignments for Mg-23 levels and the astrophysical Na-22(p, gamma)Mg-23 reaction

The 22Na(p)23Mg reaction is responsible for destruction of the long-lived radionuclide 22Naproduced during nova explosions. Since the reaction proceeds through resonances from levels in 23Mg above the proton threshold at 7.581 MeV, the properties of these levels such as excitation energies, spins, and parities are crucial ingredients to determine the 22Na(p,.)23Mg reaction rate. Despite recent studies of these levels, their spins are not well constrained in many cases. We have measured the 24Mg(p, d)23Mg transfer reaction to determine spectroscopic properties of these levels at the Holifield Radioactive Ion Beam Facility at Oak Ridge National Laboratory. The spin of the Ex = 7.788 MeV level in 23Mg is constrained to be J p = (3/2+, 5/2+) through the present work. The astrophysical 22Na(p,.)23Mg reaction rate at nova temperatures is updated accordingly. Nova nucleosynthesis model calculations using the newly updated 22Na(p,.)23Mg reaction rate shows that the final weighted abundance of the radionuclide 22Nais increased by42% compared to that obtained by using the previous 22Na(p)23Mg reaction rate of Sallaska et al. for a 1.35 M ONeMg white dwarf

Proton Decay of(21)Na for(20)Ne Energy Levels

The(24)Mg(p,alpha)Na-21 transfer reaction has been previously studied for a spectroscopic study of(21)Na [Chaet al., Phys. Rev. C96, 025810 (2017)]. In this follow-up analysis, the proton decays of the excited states of the radionuclide(21)Na, which were measured simultaneously, are reported. By investigating the coincidence between the reaction alpha-particles and decay protons, we were able to identify three groups of events that are associated with the energy levels in(20)Ne. The(20)Ne excitation energy plot was obtained as a result. The four lowest known energy levels in(20)Ne (the ground state and excited states atE(x)= 1.633, 4.247 and 4.966 MeV) were clearly observed

First measurement of proton decay from a transfer reaction to Na-21

Decay protons from excited states in Na-21 populated through a previously reported Mg-24(p, alpha) Na-21 transfer reaction [Cha et al., Phys. Rev. C 96, 025810 (2017)] were analyzed to extract the proton branching ratios of the energy levels. By utilizing 31-MeV proton beams from the Holifield Radioactive Ion Beam Facility of Oak Ridge National Laboratory and isotopically enriched Mg-24 solid targets, the decay protons were detected in coincidence with alpha particles from the (p, alpha) reaction using a silicon strip detector array. Proton decay branching ratios of several Na-21 levels were deduced for the p0 and p1 decay channels to the ground and first excited states in Ne-20, respectively