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Biomedical subjects

B Sundqvist

Publications and source records attributed to B Sundqvist.

At least 19 recordsLinked to original sources
PubMed2006

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.

Journal Article↗
PubMed2001

Magnetic carbon.

The discovery of nanostructured forms of molecular carbon has led to renewed interest in the varied properties of this element. Both graphite and C60 can be electron-doped by alkali metals to become superconducting; transition temperatures of up to 52 K have been attained by field-induced hole-doping of C60 (ref. 2). Recent experiments and theoretical studies have suggested that electronic instabilities in pure graphite may give rise to superconducting and ferromagnetic properties, even at room temperature. Here we report the serendipitous discovery of strong magnetic signals in rhombohedral C60. Our intention was to search for superconductivity in polymerized C60; however, it appears that our high-pressure, high-temperature polymerization process results in a magnetically ordered state. The material exhibits features typical of ferromagnets: saturation magnetization, large hysteresis and attachment to a magnet at room temperature. The temperature dependences of the saturation and remanent magnetization indicate a Curie temperature near 500 K.

Journal Article↗
PubMed2001

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.

Journal Article↗
PubMed2001

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.

Adolescent↗
PubMed1997

Enhancement of the molecular ion yield in plasma desorption mass spectrometry using explosive matrices.

The working hypothesis of this study was that the chemical energy of matrix material may be released, although only on a microscale, under MeV ion bombardment and may assist ejection of large intact bioorganic molecules. To test the hypothesis, the performance of several common explosives, as matrices in plasma desorption mass spectrometry, was compared to the standard matrix, nitrocellulose (NC), which is also a high explosive. Two explosives, RDX and HMX, were found to be new, effective matrices for peptides and proteins. While the performance of RDX was comparable with that of nitrocellulose, HMX gave a superior molecular ion yield and a higher average charge state of desorbed molecular ions compared with NC. Noth RDX and HMX have a similar chemical composition and structure, although the latter is a more powerful explosive. The measured total ion yield allows the conclusion that the increase in the amount of ejected material, due to the chemical energy release in high explosives under MeV ion bombardment, is limited, perhaps to a factor of 2 to 3. The fact that not all tested explosives gave molecular ions from peptides and proteins suggests that other factors, such as gas-phase chemistry, may play a significant role in molecular ion formation.

Animals↗
PubMed1997

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.

Adult↗