Molecular weight determinations of proteins by californium plasma desorption mass spectrometry.

The plasma desorption mass spectrometry method is used to determine the molecular weights of larger molecules than before, to determine the molecular weights of proteins and peptides in mixtures, and to monitor protein modification reactions. Proteins up to molecular weight 25,000 can now be studied with a mass spectrometric technique. Protein-peptide mixtures that could not be resolved with conventional techniques were successfully analyzed by this technique. The precision of the method is good enough to permit one to follow the different steps in the conversion of porcine insulin to human insulin.

Topochemical polymerization of C70 controlled by monomer crystal packing.

Polymeric forms of C60 are now well known, but numerous attempts to obtain C70 in a polymeric state have yielded only dimers. Polymeric C70 has now been synthesized by treatment of hexagonally packed C70 single crystals under moderate hydrostatic pressure (2 gigapascals) at elevated temperature (300 degrees C), which confirms predictions from our modeling of polymeric structures of C70. Single-crystal x-ray diffraction shows that the molecules are bridged into polymeric zigzag chains that extend along the c axis of the parent structure. Solid-state nuclear magnetic resonance and Raman data provide evidence for covalent chemical bonding between the C70 cages.

Effect of rare-earth component of the RE/Ni catalyst on the formation and nanostructure of single-walled carbon nanotubes.

A systematic experimental study has been carried out on the efficiency of bimetallic catalysts based on Ni and the rare-earth elements Y, La, Ce, Nd, Gd, Tb, Dy, Ho, Er, and Lu (group A) and Eu, Sm, Yb, and Tm (group B) in the synthesis of single-walled carbon nanotubes (SWNTs). The two groups give quite different results when analyzed by a combination of SEM/TEM and Raman and UV-NIR spectroscopies. The elements in group A have an obvious catalytic effect and increase the yield of SWNTs dramatically, whereas those in group B are not efficient catalysts. The diameter distribution of the synthesized SWNTs was also affected by the rare-earth element used. For group A metals, there is a tendency that the fraction of small-diameter tubes decreases with decreasing ionic radius of the rare-earth element used. EDX and X-ray analyses indicate that group A metals deposit on the cathode deposits and form rare-earth carbides, whereas no group B metals are found in cathode deposits, except for a small amount of Tm present in the form of thulium carbide. Further analysis indicates that there is a very strong correlation between the ability to form rare-earth carbides and the catalytic efficiency for the formation of SWNTs.

Individual prediction of treatment outcome in patients with temporomandibular disorders.

Out of 3159 patients referred to a specialist clinic of stomatognathic physiology, 1297 patients started treatment because of temporomandibular disorders. All those patients were divided into subgroups of patients with mainly muscular or TMJ symptoms, respectively. A prediction of the treatment outcome as good or dubious was also made. This prediction was based on the patient's history and the clinical findings. A total of 989 patients (76%) completed the treatment. They all graded the degree of improvement of their initial symptoms using a Numeric Rating Scale. An improvement of initial complaints of 50% or more was judged to be a relevant change. In 85% of the patients with mainly muscular symptoms, the treatment was predicted to have a good outcome. The corresponding figures for those patients with mainly TMJ symptoms were 93%. Not less than 88% of all the patients reported an improvement of 50% or more of their initial complaints. The possibility to predict the treatment outcome as good in patients with mainly muscular symptoms was very good: 90% fulfilled the criteria of a positive treatment result. For those with a dubious prognosis, 56% had a positive outcome of treatment. The possibility to predict treatment outcome as good in those with mainly TMJ symptoms was also very good: 94% responded positively on the treatment. Almost the same figure, 88%, of those with a poor prognosis had a positive treatment outcome.

Clinical evaluation of ceramic veneered titanium restorations according to the Procera technique.

The aim of the present study was to present the design and one-year results of a study of crowns and fixed partial dentures (FPDs) made with the Procera system. All patients at one clinic needing fixed prosthodontic restorations during a two-year period were invited. All 260 patients accepted to participate and they received 333 ceramic veneered Procera restorations-242 single crowns and 91 FPDs. The loss of patients during the one-year follow-up was only 5%. The restorations were evaluated according to a modified version of the California Dental Association rating system. Practically all Procera restorations were judged as satisfactory both at base line and at the one-year follow-up examination. Two crowns and one FPD showed fractures of the ceramic veneering. Another FPD had a fracture of a welded joint. Three single crowns came loose but could be recemented. In conclusion, the ceramic veneered Procera titanium restorations were well accepted by the patients and the success rate was high during the one-year follow-up period.

Stability of the Tomonaga-Luttinger liquid state in gamma-irradiated carbon nanotube bundles.

We report experimental results for the changes in conductivity of single-wall carbon nanotube bundles when irradiated by (60)Co γ-rays in various environments. In the current study the samples investigated were irradiated in hermetic cells, either evacuated (0.1 Pa) or filled with hydrogen or deuterium at atmospheric pressure. In situ measurements of the resistance change as a function of irradiation dose at room temperature are presented. It was found that, for all irradiation conditions, the normalized resistance versus irradiation dose demonstrates a logarithmic behaviour. A phenomenological model for the observed dependence is derived. The current-voltage characteristics of the irradiated samples were measured in the temperature range from 4.5 to 300 K using short (10 ns) electric pulses, and the results demonstrate a scaling behaviour. This scaling occurs in the universal coordinates that correspond to the Tomonaga-Luttinger liquid concept. Our results confirm the existence of the Tomonaga-Luttinger liquid phase up to room temperature in carbon nanotubes after γ-irradiation to a dose of 5 × 10(7) rad in vacuum, 1.7 × 10(7) rad in hydrogen and 1.24 × 10(8) rad in deuterium.