A tale of tails: deciphering the contribution of terminal tails to the biochemical properties of two Dps proteins from Streptomyces coelicolor

Dps proteins are members of an extensive family of proteins that oxidise and deposit iron in the form of ferric oxide, and are also able to bind DNA. Ferroxidation centres are formed at the interface of anti-parallel dimers, which further assemble into dodecameric nanocages with a hollow core where ferric oxide is deposited. Streptomyces coelicolor encodes three Dps-like proteins (DpsA, B and C). Despite sharing the conserved four-helix bundle organisation observed in members of the Dps family, they display significant differences in the length of terminal extensions, or tails. DpsA possess both N- and C-terminal tails of different lengths, and their removal affects quaternary structure assembly to varying degrees. DpsC quaternary structure, on the other hand, is heavily dependent on its N-terminal tail as its removal abolishes correct protein folding. Analysis of the crystal structure of dodecamers from both proteins revealed remarkable differences in the position of tails and interface surface area; and provides insight to explain the differences in biochemical behaviour observed while comparing DpsA and DpsC.     

Stimuli-responsive polymeric materials for human health applications

Stimuli-responsive polymers have the extraor- dinary ability to change their physical and/or chemical state after they ＂detect＂ a change in their environment; their response depends dramatically on their chemical compo- sition. This property has been used for a plethora of applications; this review highlights their utility for human health. Specifically, this review will highlight efforts in the areas of sensing and biosensing, antimicrobial/antifouling coatings, tissue engineering and regenerative medicine, and drug delivery. Specific examples are given in each of these areas, with some focus on our work engineering poly（N- isopropylacrylamide）-based microgels and other respon- sive systems.     

Sonochemical synthesis of nanostructured nickel hydroxide as an electrode material for improved electrochemical energy storage application

A facile and fast approach for the synthesis of a nanostructured nickel hydroxide(Ni(OH)_2) via sonochemical technique is reported in the present study. The X-ray diffraction results confirmed that the synthesized Ni(OH)_2 was oriented in β-phase of hexagonal brucite structure. The nanostructured Ni(OH)_2 electrode exhibited the maximum specific capacitance of 1256 F/g at a current density of 200 mA/g in 1 M KOH_((aq)). Ni(OH)_2 electrodes exhibited the pseudocapacitive behavior due to the presence of redox reaction. It also exhibited long-term cyclic stability of 85% after 2000 cycles, suggesting that the nanostructured Ni(OH)_2 electrode will play a promising role for high performance supercapacitor application.     

Studies on induction hardening of powder-metallurgy-processed Fe-Cr/Mo alloys

Induction hardening of dense Fe-Cr/Mo alloys processed via the powder-metallurgy route was studied. The Fe-3Cr-0.5Mo, Fe-1.5Cr-0.2Mo, and Fe-0.85Mo pre-alloyed powders were mixed with 0.4wt%, 0.6wt%, and 0.8wt% C and compacted at 500, 600, and 700 MPa, respectively. The compacts were sintered at 1473 K for 1 h and then cooled at 6 K/min. Ferrite with pearlite was mostly observed in the sintered alloys with 0.4wt% C, whereas a carbide network was also present in the alloys with 0.8wt% C. Graphite at prior particle boundaries led to deterioration of the mechanical properties of alloys with 0.8wt% C, whereas no significant induction hardening was achieved in alloys with 0.4wt% C. Among the investigated samples, alloys with 0.6wt% C exhibited the highest strength and ductility and were found to be suitable for induction hardening. The hardening was carried out at a frequency of 2.0 kHz for 2-3 s. A case depth of 2.5 mm was achieved while maintaining the bulk (interior) hardness of approximately HV 230. A martensitic structure was observed on the outer periphery of the samples. The hardness varied from HV 600 to HV 375 from the sample surface to the interior of the case hardened region. The best combination of properties and hardening depth was achieved in case of the Fe-1.5Cr-0.2Mo alloy with 0.6wt% C.     

Historical review and redescription of three poorly known species of the catfish genus Trichomycterus from south-eastern Brazil (Siluriformes: Trichomycteridae)

ABSTRACT

This study is primarily directed to the most poorly known species of the genus Trichomycterus, comprising five nominal species (T. florensis, T. immaculatus, T. nigricans, T. paquequerensis and T. santaeritae) endemic to south-eastern Brazil. One of them, T. nigricans, is the type species of the genus, involved in taxonomic problems for over 150 years. A detailed historical review, accompanied by examination of type specimens and recent collections, revealed that the correct type locality of T. nigricans is in the vicinity of Rio de Janeiro, not Santa Catarina as commonly appears in the literature; specimens previously misidentified as T. nigricans from Santa Catarina belong to a possibly undescribed species of the genus Cambeva; T. paquequerensis is a synonym of T. immaculatus, and T. florensis is a synonym of T. santaeritae; and the hypothesis that T. santaeritae is closely related to the Amazon Sarcoglanidinae is refuted. The three valid species are redescribed. These species are members of a clade also including T. caipora that is highly supported by molecular data, diagnosed by a pronounced posterior maxillary process and caudal fin emarginate at least in larger specimens. A subclade comprising T. caipora, T. nigricans and T. santaeritae is diagnosed by a long maxilla and a bifid anterior extremity of hypobranchial 3.