Archaeometric investigations on naturally and thermally-aged iron-gall inks using different tannin sources

This paper investigates the behavior of paper strips containing iron-gall inks prepared with tannins from different sources, subjected to natural and thermally-induced aging. Results indicate that inks containing initial concentrations of ferrous sulphate ranging from 0.2 to 10.0 g are amenable to treatment with calcium phytate, and thata good correlation exists between the recovery of excess iron and the initial concentration. Infrared spectra showed an absorption band at 1,750 cm^?1, typical of esther, solely in the samples prepared with a condensed tannin. The condensed nature of this tannin produced a different oxidation pattern, with iron removal inferior to those observed from inks produced with hydrolisable tannins. When tannic acid was used ferrous iron removals ranged from 0.050 to 1.800 g, decreasing to 0.5 g in the presence of copper; the same behavior was observed for the remaining hydrolisable tannins, with a lower recovery from the condensed tannin. The adopted natural aging procedure released a higher amount of ferrous iron compared to ASTM thermal aging. This was probably due to the marked effect of humidity, not considered in the thermal procedure. A series of archaeometric possibilities were used to help elucidate the degradation of cellulose strips impregnated with iron-gall inks.      

Millimeter-wave time-resolved studies of HCO+-H2 inelastic collisions

A novel ion cell has been constructed for the purpose of studying rotationally inelastic collisions involving truly thermal molecular ions at low temperatures. With this ion cell, time-resolved double resonance (pump-probe) spectroscopic experiments have been performed to determine the cross sections for relaxation of the J = 2 state of HCO+ in collisions with normal-H2 at temperatures around 40 and 77 K. The HCO+ is pumped through the J = 2<--1 transition and probed via the J = 3<--2 transition. The cross sections at the lower temperature are slightly below those predicted by the simple Langevin theory, while those at the higher temperature are in good agreement with this theory.     

Das Cacao?l

Ohne Zusammenfassung     

Secondary interactions in n‐(chloromethyl)pyridinium chlorides (n = 2, 3, 4)

In the isomeric title compounds, viz. 2‐, 3‐ and 4‐(chloro­methyl)pyridinium chloride, C₆H₇ClN⁺·Cl^?, the secondary interactions have been established as follows. Classical N—H?Cl^? hydrogen bonds are observed in the 2‐ and 3‐isomers, whereas the 4‐isomer forms inversion‐symmetric N—H(?Cl^??)₂H—N dimers involving three‐centre hydrogen bonds. Short Cl?Cl contacts are formed in both the 2‐isomer (C—Cl?Cl^?, approximately linear at the central Cl) and the 4‐isomer (C—Cl?Cl—C, angles at Cl of ca 75°). Additionally, each compound displays contacts of the form C—H?Cl, mainly to the Cl^? anion. The net effect is to create either a layer structure (3‐isomer) or a three‐dimensional packing with easily identifiable layer substructures (2‐ and 4‐isomers).     

Some aspects of fundamental chemistry of the Universal Extraction (UNEX) process for the simultaneous separation of major radionuclides (cesium, strontium, actinides, and lanthanides) from radioactive wastes

Summary Scientists at the Idaho National Laboratory (INL) and Khlopin Radium Institute (KRI) collaboratively developed and validated the concept of a Universal Extraction (UNEX) process for simultaneously removing the major radionuclides (Cs, Sr, actinides, and lanthanides) from acidic radioactive waste in a single solvent extraction process. The process chemistry is unique and complicated, since the extractants, chlorinated cobalt dicarbollide (CCD), polyethylene glycol (PEG), and diphenyl-N,N-di-n-butylcarbamoylmethylphosphine oxide (Ph₂CMPO), operatesynergistically to extract the major radionuclides.A combination of classical chemistry techniques, infrared (IR) spectroscopy, and nuclear magnetic resonance (NMR) spectroscopy were utilized to identify and explain the structures formed in the organic phase with protons or metal ions. Model systems, CCD-PEG and CCD-bidentate organophosphorus compounds were studied and possible structures of complexes, existing in the organic phase, are proposed and properties of the UNEX extractant are discussed.     

FTIR and XPS study of Pt nanoparticle functionalization and interaction with alumina

Platinum nanoparticles with a mean size of 1.7 nm were synthesized by reduction in sodium acetate solution in 1,2-ethanediol. The particles were then functionalized with dodecylamine, dodecanethiol, and omega-mercapto-undecanoic acid (MUDA). Fourier transform infrared (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS) showed important variations of the particle surface state with functionalization whereas their structure differs only slightly. Platinum-to-sulfur charge transfer inferred from XPS of thiol-coated particles enabled the identification of the formation of Pt (delta+)-S (delta-) bonds. The native carbon monoxide (CO) at the surface of the particles was a very efficient probe for following the functionalization of the particles by FTIR. The red shift of nu(CO) accounts for the nature of the ligands at the surface of the particles and also for their degree of functionalization. Immobilization on alumina substrates of particles functionalized with MUDA was realized by immersion in colloidal solutions. Free molecules, isolated particles, and aggregates of particles interconnected by hydrogen bonds at the surface of alumina were evidenced by FTIR. With successive washings, the energy variation of the CO stretch of carbon monoxide and of carboxylic acid groups and the relative intensity nu(CH2)/nu(CO) showed that the free molecules are eliminated first, followed by aggregates and less-functionalized particles. Particles presenting a high degree of functionalization by MUDA remain and interact strongly with alumina.