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Cobalt Copper Zinc Ferrite (CoCuZnF) was synthesized using the co-precipitation method and characterized by various physicochemical instrumental techniques like UV-Vis, Raman, and N2-adsorption-desorption analysis to identify its structural parameters. Moreover, the catalytic study of nano CoCuZnF on ammonium perchlorate (AP) and AP-based composite solid propellant (CSP) was studied using DSC analysis. Furthermore, many kinetic models were employed to study its kinetics parameters. The thermal decomposition peak of AP was found to be decreased by 65–66°C in the presence of 1% by mass CoCuZnF additive. The activation energy of AP was found to be decreased by ~27-28% in the presence of CoCuZnF. The burn rate of AP-based CSP was found to be increased by 0.77 mm s−1 when CoCuZnF was used as an additive. [ABSTRACT FROM AUTHOR]

Composite solid propellants (CSPs) have been used as propellants in rocket propellant applications. The major ingredients of these CSPs are metallic fuel, a polymeric binder, a curing agent, and an oxidizer. The oxidizer provides an internal source of oxygen and therefore, propellants can burn even when there is no availability of external oxygen. The oxidizer constitutes a major portion (70–80%) of CSPs. The oxidizer is a high energetic material that detonates with the sudden release of heat and a large number of gases. Ammonium perchlorate (AP, NH4ClO4) is most widely used as an oxidizer in CSPs and therefore, the thermal decomposition of AP can affect the burning characteristics of CSPs. The addition of nanomaterials reduces the thermal decomposition of AP. In the present work, the catalytic activity of quaternary ferrite- NiCoZn ferrite (NiCoZnF) has been studied. It was found that in the presence of NiCoZnF, high thermal decomposition of ammonium perchlorate reduces from 395°C to 304.56°C. The decrement in the activation energy of AP in the presence of NiCoZnF also confirms its excellent catalytic activity. Furthermore, the burn rate of AP/HTPB-based propellant in the presence of NiCoZnF was increased from 2.22 mm/s to 3.2 mm/s. [ABSTRACT FROM AUTHOR]

Ferrites especially transition metal based catalysts show a versatile catalytic ability for thermal decomposition of solid propellants. Herein, XRD, UV‐visible spectroscopy, Raman spectroscopy, and N2‐adsorption desorption analyses were used to analysis trimetallic nano‐ferrite NiCuZnFe2O4 synthesized by co‐precipitation method. The particle size of the NiCuZnFe2O4 found between 9–20 nm. Moreover, we have studied catalytic activity of tri metal ferrite (NiCuZnFe2O4) on thermal decomposition of propellant oxidizer ammonium perchlorate (AP) and monitored by simultaneous thermal analyses. The increased surface area, smaller band gap, and crystalline Raman phase of the AP + NiCuZnFe2O4 mixture contributed to substantial physico‐chemical and catalytic outcomes. The combination of AP with the nano‐catalyst NiCuZnFe2O4 reduced ignition delay, which was ascribed to a lower thermal decomposition temperature. [ABSTRACT FROM AUTHOR]

The Indian Environmental Protection Act (EPA) came into force in 1986 after Bhopal Gas Tragedy. It stipulates that no person or industry or processor shall discharge or emit environmental pollutants in excess of prescribed standards. Dihydroxyl ammonium 5,5′-bistetrazole-1,1′-diolate, abbreviated as TKX-50, was synthesized in this laboratory. During synthesis of TKX-50 a large volume of effluent was generated, which was acidic and hazardous in nature and therefore can damage the environment if discharged without proper treatment. Literature survey reveals that TKX-50 effluent analysis and its treatment have not been reported so far. In order to meet EPA norms and protect the environment TKX effluent samples of different steps of synthesis were collected and analyzed for environmental parameters such as pH, chemical oxygen demand (COD), bio-chemical oxygen demand (BOD), total dissolved solids (TDS) and bioassay test (toxicity to zebra fish survival) followed by the treatment of composite effluent. This paper presents analysis results of TKX-50 effluent samples before and after treatment. The results of finally treated TKX-50 effluent indicate that the same can be safely discharged on land for irrigation without adverse effect on environment. This study may be suitable for environmentalists and community of high energy materials. [ABSTRACT FROM AUTHOR]

The review describes the recent developments in the green synthetic methods of nitro compounds involving environmentally benign approaches such as, use of solid-supported reagents, microwave-assisted reactions, ionic liquids, ultrasound assisted nitration reactions, gas phase nitration and vapor phase nitration. [ABSTRACT FROM AUTHOR]

The BRCA1 holoenzyme complex plays an important role in DNA damage repair. ABRAXAS is a newly discovered component of this complex and its C-terminal region directly binds to the BRCA1 BRCT domain. Single crystals of the BRCA1 BRCT-ABRAXAS complex grown by co-crystallization belonged to space group P41212, with unit-cell parameters a = b = 187.18, c = 85.31 Å. Diffraction data were collected on the BM-14 beamline at the ESRF. Molecular-replacement calculations using Phaser led to three molecules in the asymmetric unit and a high solvent content of 76%. [ABSTRACT FROM AUTHOR]

Tyrosinases belong to the type-III copper enzyme family, which is involved in melanin production in a wide range of organisms. Despite similar overall characteristics and functions, their structures, activities, substrate specificities and regulation vary. The tyrosinase from the bacterium Verrucomicrobium spinosum ( vs Tyr) is produced as a pre-pro-enzyme in which a C-terminal extension serves as an inactivation domain. It does not require a caddie protein for copper ion incorporation, which makes it similar to eukaryotic tyrosinases. To gain an understanding of the catalytic machinery and regulation of vs Tyr activity, we determined the structure of the catalytically active "core domain" of vs Tyr by X-ray crystallography. The analysis showed that vs Tyr is an atypical bacterial tyrosinase not only because it is independent of a caddie protein but also because it shows the highest structural (and sequence) similarity to plant-derived members of the type-III copper enzyme family and is more closely related to fungal tyrosinases regarding active site features. By modelling the structure of the pre-pro-enzyme using AlphaFold, we observed that Phe453, located in the C-terminal extension, is appropriately positioned to function as a "gatekeeper" residue. Our findings raise questions concerning the evolutionary origin of vs Tyr.

MERIT40 (MEdiator of RAP80 Interaction and Targeting 40) is a novel associate of the BRCA1-complex and plays an essential role in DNA damage repair. It is the least characterized protein of BRCA1-complex and mainly responsible for maintaining the complex integrity. However, its structural and functional aspects of regulating the complex stability still remain elusive. Here, we carried out a comprehensive examination of MERIT40 biophysical properties and identified its novel interacting partner which would help to understand its role in BRCA1-complex. The recombinant protein was purified by affinity chromatography and unfolding pathway was determined using spectroscopic and calorimetric methods. Molecular model was generated using combinatorial approaches of modeling, and monomer-monomer docking was carried out to identify dimeric interface. Disordered region of MERIT40 was hatchet using trypsin and chymotrypsin to illustrate the existence of stable domain whose function was speculated through DALI search. Our findings suggest that MERIT40 forms a dimer in a concentration-independent manner. Its central region shows remarkable stability towards the protease digestion and has structural similarity with vWA-like region, a domain mainly present in complement activation factors. MERIT40 undergoes a three-state unfolding transition pathway with a dimeric intermediate. It interacts with adaptor molecule of BRCA1-complex, called ABRAXAS, thus help in extending the bridging interaction among various members which further stabilizes the whole complex. The results presented in this paper provide first-hand information on structural and folding behavior of MERIT40. These findings will help in elucidating the role of protein-protein interactions in stabilization of BRCA1-complex.