Boswellic acids are the main well-known active components of the resin of
Boswellia carteri (Burseraceae) and these are still dealing with the ethnomedicinal use for the treatment of rheumatoid ...arthritis and other inflammatory diseases. Although several studies have already been reported on the pharmacological properties, especially on the anti-inflammatory activity, of
Boswellia carteri resin and boswellic acids, the ethnomedicinal importance of
Boswellia carteri and its components, boswellic acids, prompted us to undertake detailed investigation on the constituents of the resin and their anti-inflammatory activity. Fifteen triterpene acids, viz., seven of the β-boswellic acids (ursane-type) (
1–
7), two of the α-boswellic acids (oleanane-type) (
8,
9), two of the lupeolic acids (lupane-type) (
10,
11), and four of the tirucallane-type (
12–
14,
16), along with two cembrane-type diterpenes (
17,
18), were isolated and identified from the methanol extract of the resin of
Boswellia carteri. Upon evaluation of 17 compounds,
1–
14 and
16–
18, and compound
15, semi-synthesized from
14 by acetylation, for their inhibitory activity against 12-
O-tetradecanoylphorbol-13-acetate (TPA)-induced inflammation (1
μg/ear) in mice, all of the compounds, except for
18, exhibited marked anti-inflammatory activity with a 50% inhibitory dose (ID
50) of 0.05–0.49
mg/ear.
Development of Fine Multifilamentary Conductors Banno, N.; Takeuchi, T.; Tanaka, K. ...
IEEE transactions on applied superconductivity,
2009-June, 2009-06-00, 20090601, Letnik:
19, Številka:
3
Journal Article
Recenzirano
A new configuration of Nb 3 Al conductor with a fine multifilamentary structure is presented. The wire is fabricated by a simple re-stacking (RS) method, in which rapid-quenched ductile BCC Nb-Al ...phase wires are re-stacked into a stabilizing Cu tube and co-drawn into a final form. Such a simple stabilization method will be effective to cut the Nb 3 Al fabrication cost. The developed RS Nb 3 Al conductor has a non-Cu J c of almost about 1000 A/mm 2 at 15 T, 4.2 K. The effective filament diameter is 14 mum and the hysteresis loss (+/- 3 T) is 370 mJ/cm 3 , which is small enough with respect to the ITER target specification.
We attempted to reduce the matrix ratio down to 0.5 and 0.25 for RHQT (rapid-heating, quenching and transformation) Nb 3 Al wires, which is directly related to improvement of the non-Cu J c . The Ta ...matrix was chosen to improve the wire strength. It was found that the matrix ratio of 0.25 is too small to carry out RHQ treatment although drawing was possible by using cassette-roller dies (CRDs) as well as conical dies. The reduction of the matrix ratio down to 0.5 can also be achieved. However, the scale-up would make the drawing very difficult. It would be necessary for the scale-up to improve adhesion among the jelly-roll (JR) cores and also the outer Ta sheath in the multi-billet. The RHQ treatment was possible for the wire with a matrix ratio of 0.5. However, it was successful only when the wire diameter was less than 1.13 mm. It is necessary to suppress the experienced bend strain in the operation. The non-Cu J c was found to be improved by about 20% by the reduction of the matrix ratio, compared to conventional Nb 3 Al wires.
Rapid heating/quenching and transformation (RHQT)-processed Nb3Al wires possess better strain tolerance than Nb3Sn wires and exhibit similar high-field properties. Therefore, Nb3Al wires might be ...promising candidates for use in future high-field accelerator magnets. For this reason, we have been developing RHQT-processed Nb3Al wires for a number of years. During this development, magnetization measurements on several samples have been carried out as a function of either temperature or the magnetic field. This paper presents some of the results of the magnetization measurements performed.
We have been developing rapid heating, quenching and transformation (RHQT) processed Nb 3 Al wires for next-generation accelerator magnets that require magnetic fields between 12 and 17 T. However, ...it has recently been found that the conventional Nb-matrix wire shows a rather strong magnetic instability at low fields. Taking this into consideration, we have begun developing Ta-matrix Nb 3 Al wires. We have fabricated a precursor wire with a Ta-matrix volume fraction of 0.8, and the mechanical properties of the RHQ-processed wire were examined. The effects of the RHQ condition and the area reduction (AR) after RHQ on the critical current density ( J c ) , and magnetization of the wire have also been examined. This paper describes the properties for the Ta-matrix wire in comparison with those of the Nb-matrix wire.
The minimum quench energy ( MQE ) and normal zone propagation velocity ( NZPV ) of three kinds of Nb 3 Al superconductors fabricated by the rapid heating, quenching and transformation (RHQT) process ...were measured under various conditions of applied magnetic field (10-14 T), temperature (7-11 K), and transport current (80-95% of the critical current), while cooled by a cryocooler for developing the over 20-T class cryogen-free magnet. As a result, MQE values were related to the critical current density ( J c ); high MQE was obtained for low J c . It is assumed that J c has a stronger influence on the MQE than specific heat, thermal conductivity, resistivity, and other parameters of the composite superconductor including the matrix and the stabilizer. NZPV was mainly proportional to the transport current density varying with applied field and temperature. The second contribution to NZPV is assumed to be heat capacity depending on the wire configuration.
The mechanical Cu-cladding method is favourable to incorporate stabilizer into the rapid-heating, quenching and transformation (RHQT) processed Nb3Al conductor for NMR insert coil uses, because an ...appropriate mechanical deformation of bcc Nb-Al supersaturated solid solution (Nb(Al)ss) is effective in transforming it in a short time, making the resultant superconducting properties large and insensitive to the temperature ramp rate during transformation annealing. In order to examine the drawability of a Cu-clad stabilized conductor with rectangular dies that might be effective in finishing the conductor with a precision dimension, which would eventually be a key to homogenizing the magnetic field of NMR magnet, the tensile loading test at room temperature was performed for Cu-clad conductors. For comparison, the tensile properties of as-quenched wires and round-to-round deformed bare wires were also examined. A fracture elongation reached as much as 11% for as-quenched Nb/Nb(Al)ss composites, but only 3.5% for Cu-clad conductors. Effects of pre-annealing on tensile properties were also studied. Ductility does not seem to deteriorate after pre-annealing at temperatures less than 500 deg C, but the pre-annealing at 600 deg C apparently reduces the elongation. Pre-annealing did not improve the drawability of Cu-clad stabilized conductor with rectangular dies.
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