8 research outputs found
Critical temperature depression and persistent photoconductivity in ion irradiated YBa2Cu3O7−x films and YBa2Cu3O7−x/PrBa2Cu3O7 superlattices
Osmium Models of Intermediates Involved in Catalytic Reactions of Alkylidenecyclopropanes
The
complex [OsCp{κ<sup>3</sup>-<i>P</i>,<i>C</i>,<i>C</i>-P<sup>i</sup>Pr<sub>2</sub>[C(CH<sub>3</sub>)CH<sub>2</sub>]}(CH<sub>3</sub>CN)]PF<sub>6</sub> (<b>1</b>) reacts
with (2-pyridyl)methylenecyclopropane, at room temperature, to give
initially the cyclobutylidene derivative [Os(η<sup>5</sup>-C<sub>5</sub>H<sub>5</sub>)(CCH<sub>2</sub>CH<sub>2</sub>CH-<i>o</i>-C<sub>5</sub>H<sub>4</sub>N){P<sup>i</sup>Pr<sub>2</sub>[C(Me)CH<sub>2</sub>]}]PF<sub>6</sub> (<b>2</b>), as a result of the ring expansion
of the alkylidenecyclopropane unit. Over time complex <b>2</b> rearranges into the cyclobutene derivative [Os(η<sup>5</sup>-C<sub>5</sub>H<sub>5</sub>){η<sup>2</sup>-C(CHCH<sub>2</sub>CH<sub>2</sub>)-<i>o</i>-C<sub>5</sub>H<sub>4</sub>N}{P<sup>i</sup>Pr<sub>2</sub>[C(Me)CH<sub>2</sub>]}]PF<sub>6</sub> (<b>3</b>). The reaction of <b>1</b> with (2-pyridyl)methylenecyclopropane at room temperature
also affords the phosphinomethanide metallacycle [Os(η<sup>5</sup>-C<sub>5</sub>H<sub>5</sub>){κ<sup>4</sup>-<i>P</i>,<i>C</i><sup>a</sup>,<i>C</i><sup>b</sup>,<i>N</i>-P<sup>i</sup>Pr<sub>2</sub>[C<sup>a</sup>(Me)CH<sub>2</sub>CH)(C<sup>b</sup>CH<sub>2</sub>CH<sub>2</sub>-<i>o</i>-C<sub>5</sub>H<sub>4</sub>N]}]PF<sub>6</sub> (<b>4</b>) as a minor product, which becomes the major product of the reaction
at 45 °C. This osmacyclopentane results from the C–C coupling
of the isopropenyl substituent of the phosphine ligand and the organic
substrate. In acetone at 75 °C, the reaction of <b>1</b> with (2-pyridyl)methylenecyclopropane leads to the 2-alkylidene-1-osmacyclobutane
[Os(η<sup>5</sup>-C<sub>5</sub>H<sub>5</sub>){κ<sup>3</sup>-<i>N</i>,<i>C</i><sup>a</sup>,<i>C</i><sup>b</sup>-C<sup>a</sup>(CH<sub>2</sub>C<sup>b</sup>H<sub>2</sub>)(CH-<i>o</i>-C<sub>5</sub>H<sub>4</sub>N)}{P<sup>i</sup>Pr<sub>2</sub>[C(Me)CH<sub>2</sub>]}]PF<sub>6</sub> (<b>5</b>), as a consequence of the oxidative addition of
one of the C(sp<sup>2</sup>)–C(sp<sup>3</sup>) bonds of the
cyclopropane unit of the substrate to the osmium atom, along with <b>6</b>, a diastereomer of <b>4</b>. Complexes <b>3</b>–<b>5</b> have been characterized by X-ray diffraction
analysis. DFT calculations suggest that all of the reaction products
are derived from a common key 1-osma-2-azacyclopent-3-ene intermediate
(<b>D</b>)
Osmium Models of Intermediates Involved in Catalytic Reactions of Alkylidenecyclopropanes
The
complex [OsCp{κ<sup>3</sup>-<i>P</i>,<i>C</i>,<i>C</i>-P<sup>i</sup>Pr<sub>2</sub>[C(CH<sub>3</sub>)CH<sub>2</sub>]}(CH<sub>3</sub>CN)]PF<sub>6</sub> (<b>1</b>) reacts
with (2-pyridyl)methylenecyclopropane, at room temperature, to give
initially the cyclobutylidene derivative [Os(η<sup>5</sup>-C<sub>5</sub>H<sub>5</sub>)(CCH<sub>2</sub>CH<sub>2</sub>CH-<i>o</i>-C<sub>5</sub>H<sub>4</sub>N){P<sup>i</sup>Pr<sub>2</sub>[C(Me)CH<sub>2</sub>]}]PF<sub>6</sub> (<b>2</b>), as a result of the ring expansion
of the alkylidenecyclopropane unit. Over time complex <b>2</b> rearranges into the cyclobutene derivative [Os(η<sup>5</sup>-C<sub>5</sub>H<sub>5</sub>){η<sup>2</sup>-C(CHCH<sub>2</sub>CH<sub>2</sub>)-<i>o</i>-C<sub>5</sub>H<sub>4</sub>N}{P<sup>i</sup>Pr<sub>2</sub>[C(Me)CH<sub>2</sub>]}]PF<sub>6</sub> (<b>3</b>). The reaction of <b>1</b> with (2-pyridyl)methylenecyclopropane at room temperature
also affords the phosphinomethanide metallacycle [Os(η<sup>5</sup>-C<sub>5</sub>H<sub>5</sub>){κ<sup>4</sup>-<i>P</i>,<i>C</i><sup>a</sup>,<i>C</i><sup>b</sup>,<i>N</i>-P<sup>i</sup>Pr<sub>2</sub>[C<sup>a</sup>(Me)CH<sub>2</sub>CH)(C<sup>b</sup>CH<sub>2</sub>CH<sub>2</sub>-<i>o</i>-C<sub>5</sub>H<sub>4</sub>N]}]PF<sub>6</sub> (<b>4</b>) as a minor product, which becomes the major product of the reaction
at 45 °C. This osmacyclopentane results from the C–C coupling
of the isopropenyl substituent of the phosphine ligand and the organic
substrate. In acetone at 75 °C, the reaction of <b>1</b> with (2-pyridyl)methylenecyclopropane leads to the 2-alkylidene-1-osmacyclobutane
[Os(η<sup>5</sup>-C<sub>5</sub>H<sub>5</sub>){κ<sup>3</sup>-<i>N</i>,<i>C</i><sup>a</sup>,<i>C</i><sup>b</sup>-C<sup>a</sup>(CH<sub>2</sub>C<sup>b</sup>H<sub>2</sub>)(CH-<i>o</i>-C<sub>5</sub>H<sub>4</sub>N)}{P<sup>i</sup>Pr<sub>2</sub>[C(Me)CH<sub>2</sub>]}]PF<sub>6</sub> (<b>5</b>), as a consequence of the oxidative addition of
one of the C(sp<sup>2</sup>)–C(sp<sup>3</sup>) bonds of the
cyclopropane unit of the substrate to the osmium atom, along with <b>6</b>, a diastereomer of <b>4</b>. Complexes <b>3</b>–<b>5</b> have been characterized by X-ray diffraction
analysis. DFT calculations suggest that all of the reaction products
are derived from a common key 1-osma-2-azacyclopent-3-ene intermediate
(<b>D</b>)
Analysis of Autoantibody Profiles in Osteoarthritis Using Comprehensive Protein Array Concepts
Osteoarthritis
(OA) is the most common rheumatic disease and one
of the most disabling pathologies worldwide. To date, the diagnostic
methods of OA are very limited, and there are no available medications
capable of halting its characteristic cartilage degeneration. Therefore,
there is a significant interest in new biomarkers useful for the early
diagnosis, prognosis, and therapeutic monitoring. In the recent years,
protein microarrays have emerged as a powerful proteomic tool to search
for new biomarkers. In this study, we have used two concepts for generating
protein arrays, antigen microarrays, and NAPPA (nucleic acid programmable
protein arrays), to characterize differential autoantibody profiles
in a set of 62 samples from OA, rheumatoid arthritis (RA), and healthy
controls. An untargeted screen was performed on 3840 protein fragments
spotted on planar antigen arrays, and 373 antigens were selected for
validation on bead-based arrays. In the NAPPA approach, a targeted
screening was performed on 80 preselected proteins. The autoantibody
targeting CHST14 was validated by ELISA in the same set of patients.
Altogether, nine and seven disease related autoantibody target candidates
were identified, and this work demonstrates a combination of these
two array concepts for biomarker discovery and their usefulness for
characterizing disease-specific autoantibody profiles
Isolation and partial characterization of a novel and uncommon two-chain 64-kDa ribosome-inactivating protein from the bark of elder ( Sambucus nigra
Enterotoxigenic Potential of Staphylococcus intermedius
Staphylococcal food poisoning (SFP) caused by enterotoxigenic staphylococci is one of the main food-borne diseases. In contrast to Staphylococcus aureus, a systematic screening for the enterotoxins has not yet been performed on the genomic level for the coagulase-positive species S. intermedius. Therefore, the enterotoxigenic potential of 281 different veterinary (canine, n = 247; equine, n = 23; feline, n = 9; other, n = 2) and 11 human isolates of S. intermedius was tested by using a multiplex PCR DNA-enzyme immunoassay system targeting the staphylococcal enterotoxin genes sea, seb, sec, sed, and see. Molecular results were compared by in vitro testing of enterotoxin production by two immunoassays. A total of 33 (11.3%) S. intermedius isolates, including 31 (12.6%) canine isolates, 1 equine isolate, and 1 human isolate, tested positive for the sec gene. In vitro production of the respective enterotoxins was detected in 30 (90.9%) of these isolates by using immunological tests. In contrast, none of 65 veterinary specimen-derived isolates additionally tested and comprising 13 (sub)species of coagulase-negative staphylococci were found to be enterotoxigenic. This study shows on both molecular and immunological levels that a substantial number of S. intermedius isolates harbor the potential for enterotoxin production. Since evidence for noninvasive zoonotic transmission of S. intermedius from animal hosts to humans has been documented, an enterotoxigenic role of this microorganism in SFP via contamination of food products may be assumed