We present Giant Metrewave Radio Telescope (GMRT) observations for three (viz., DDO 68, SDSS J2104−0035 and UGC 772) of the six most metal‐deficient actively star‐forming galaxies known. Although there is a debate as to whether these galaxies are undergoing their first episode of star formation or not, they are ‘young’ in the sense that their interstellar medium is chemically unevolved. In this regard, they are the nearest equivalents of young galaxies in the early Universe. All three galaxies, that we have observed, have irregular H i morphologies and kinematics, which we interpret as either due to tidal interaction with neighbouring galaxies, or the consequences of a recent merger. The remaining three of the six most metal‐deficient galaxies are also known to have highly disturbed H i distributions and are interacting. It is interesting because these galaxies were chosen solely on the basis of their metallicity and not for any particular signs of interaction. In this sense (i.e. their gas has not yet had time to settle into a regular disc), one could regard these extremely metal deficient (XMD) galaxies as ‘young’. The current star‐formation episode is likely to have been triggered by interaction/merger. It is also possible that the tidal interaction has lead to enhanced mixing with metal‐poor gas in outer disc, and hence to a low gas‐phase metallicity in the central star‐forming regions. We also try to determine the threshold gas density for star‐formation in our sample of galaxies, and find that in general these galaxies do not show a one‐to‐one correspondence between regions of high H i column density and regions with current star formation. However, to the extent that one can define a threshold density, its value (∼1021 atoms cm−2) is similar to that in galaxies with much higher metallicity. The highest column densities that we detect in regions far outside star‐forming regions (i.e. a lower limit to the star‐formation threshold) are ∼2 × 1021 atoms cm−2.

A new family of unsymmetrical β-TPA appended ‘push–pull’ porphyrins has been synthesized in good yield for the first time. They exhibited red shifted broad absorption spectral features with high dipole moments and tunable redox properties.

We present Giant Metrewave Radio Telescope H i observations of an extremely metal‐deficient galaxy SBS 1129+576. SBS 1129+576 has a weighted mean oxygen abundance of 12 + log (O/H) = 7.41 ± 0.07, or 1/18 of the solar value. Our H i observations show that the galaxy is strongly interacting with a companion (projected separation ∼27 kpc) galaxy, SBS 1129+577. H i emission from a third, smaller galaxy, SDSS J113227.68+572142.3, is also present in the data cube. We study the H i morphology and kinematics of this small group at angular resolutions ranging from ∼40 to 8 arcsec. The low‐resolution map shows a bridge of emission connecting the two larger galaxies and a large one‐armed spiral distortion of the disc of SBS 1129+577. We measure H i masses of ∼4.2 × 108, ∼2.7 × 109 and ∼2.1 × 108 M⊙ for SBS 1129+576, SBS 1129+577 and the gas in the bridge, respectively. Assuming that most of the bridge gas originally came from SBS 1129+576, approximately one‐third of its original gas mass has been stripped off. The third smaller galaxy has an H i mass of (MH I∼ 1.1 × 107 M⊙) and does not show any sign of interaction with the other two galaxies. The higher‐resolution maps show that SBS 1129+577 has a central bar and a ring surrounding the bar; there is also a hint of an integral‐shaped warp in SBS 1129+576. All these features are very likely to have been induced by the tidal interaction. In both SBS 1129+576 and SBS 1129+577, there is, in general, a good correspondence between regions with high H i column density and those with ongoing star formation. The two brightest H ii regions in SBS 1129+576 have (inclination‐corrected) gas column densities of ∼1.6 × 1021 and ∼1.8 × 1021 atoms cm−2, respectively. The inclination‐corrected H i column density near the H ii regions in SBS 1129+577 is generally above ∼2.0 × 1021 atoms cm−2. These values are close to the threshold density for star formation observed in other blue compact galaxies. In contrast to SBS 1129+576 and SBS 1129+577 which are very gas‐rich, the third member of this group, SDSS J113227.68+572142.3, is gas‐poor.

Water-dispersible Pluronic stabilized Fe3O4 magnetic nanoparticles were developed for intracellular delivery of hydrophobic anticancer drug.