Effect of carbon addition on the glass-forming ability of mechanically alloyed Fe-based alloys

The effect of carbon addition on the glass-forming ability (GFA) of mechanically alloyed Fe-based Fe(42)M(28)Zr(10)B(20) (M=Ni, Al, or Ge) amorphous alloy systems was investigated. It was shown that when B was partially replaced by 10 at. % C in the Fe-Ni-Zr-B and Fe-AI-Zr-B alloy systems, the GFA of the systems had increased significantly, as determined by the reduced milling time required for amorphization. However, when carbon was added to the Fe-Ge-Zr-B alloy system, the GFA was decreased drastically and no amorphization was observed. The role of carbon on the GFA of alloy systems has been discussed from the thermodynamic and kinetic points of view

Lattice contraction during amorphization by mechanical alloying

Amorphization has been achieved in blended elemental Fe-based multicomponent alloy powders by mechanical alloying. The effect of Nb addition to the Fe(42)Ni(28)Zr(10-x)Nb(x)B(20) alloy in the composition range of 1-6 at. % Nb has been investigated and it was shown that the glass-forming ability (GFA) of the alloys, defined as the milling time required to produce an amorphous phase, improved with Nb addition. The improvement was not regular; the highest GFA was achieved at an Nb level of 2 at. %. Associated with the amorphization process, lattice contraction was noted. The processes of occurrence of the amorphous phase in this alloy system, maximum GFA in the alloy with 2 at. % Nb, and lattice contraction were explained on the basis of the atomic strain model developed first for binary alloys and extended later to ternary and multicomponent alloys, and the change in coordination number with the size ratio of the constituent atoms

Hydrology of the Korapuzha estuary, Malabar, Kerala State

A preliminary enquiry on the hydrological and planktological conditions in the river mouth region was conducted during the period 1950-52 and the results published in an abstract form (George, 1953a). This study was later extended to cover the 25 Ian seaward region of the estuary in 1954. As is well known, the Malabar coast is highly productive from the fisheries point of view and it was also observed that the sea waters of the inshore region off Calicut are rich in plankton and nutrient salts (George, 1953b). Results of the present investigation would therefore serve to assess the influence of land drainage in the enrichment and replenishment of the coastal waters and allied factors

Microencapsulation of Paraffin Wax in Melamine-Formaldehyde for use in Thermal Management Study

Melamine formaldehyde microcapsules containing paraffin wax as phase change material (PCM) were synthesized. Free space was generated in-situ inside microcapsules. These were characterized by FTIR Spectrophotometer, Scanning electron microscope (SEM), Differential Scanning colorimeter (DSC), and optical microscope. It was confirmed that PCM was successfully encapsulated inside the shell material. Encapsulated PCM showed good phase change properties during heating and cooling. Enthalpy value of about 100 J/g was observed. The shape of the microcapsule, showing rough morphology is expected to help during processing and crystallization. It has been experimentally confirmed that no leakage occurs during the melting of PCM. Effectiveness in temperature control in a hot environment was also found to be satisfactory

Mechanically induced fcc phase formation in nanocrystalline hafnium

A face-centered-cubic (fcc) phase was obtained in high-purity hafnium (Hf) metal powders subjected to mechanical milling in a high-energy SPEX shaker mill. X-ray diffraction and electron microscopy techniques were employed to evaluate the structural changes in the milled powder as a function of milling time. The effects of mechanical milling included a reduction in grain size, an increase in lattice strain, and formation of an fcc phase instead of an equilibrium hexagonal-close-packed (hcp) phase. During milling, the grain size of Hf decreased to below about 7 nm. Additionally, there was approximately 6% increase in atomic volume during the formation of the fcc phase. Chemical analysis of the milled powder indicated the presence of significant amounts of interstitial impurities. Even though any or all of the above factors could contribute to the formation of the fcc phase in the milled powder, it appears that the high level of interstitial impurities is at least partially responsible for the formation of the fcc phase

LIQUID-QUENCHED METAL-METAL GLASSES

A wide variety of amorphous alloys (metallic glasses) containing only metals has been produced during the last few years. These metastable materials exhibit interesting thermal, electrical and magnetic properties and can be prepared in a very wide composition range. The composition ranges for the formation, thermal properties and crystallization behavior of the metal-metal glasses are presented in this review

IN SILICO ANALYSIS OF INHIBITOR AND SUBSTRATE BINDING SITE OF SERRAPEPTIDASE FROM SERRATIA MARCESCENS MTCC 8708

Objective: Serrapeptidase is a therapeutic enzyme broadly used as an anti-inflammatory drug to treat inflammatory diseases like arthritis, bronchitis, fibrocystic breast disease and sinusitis. The objective of present study is in silco analyzes of the substrate and inhibitor binding sites of serratiopeptidase, expressed from a cloned gene.Methods: The gene encoding Serrapeptidase was amplified from genomic DNA of Serratia marcescens MTCC 8707, an isolated from the flowers of summer squash plants. The gene was sequenced, the nucleotide sequence of 1464 nucleotides was submitted to Gen Bank nucleotide database and accession number GI: KP869847 obtained. The develop amino acid sequence was used to predict 3D structure using different bioinformatics tools and software's Further, CABS-dock and Swiss Dock, the docking servers were used for enzyme-substrate/inhibitor binding site analysis. The inflammatory mediators, bradykinin, and substance-P were used as substrates, whereas, EDTA and Lisinopril were used as an inhibitor for serrapeptidase. UCSF Chimera program was used for interactive visualization and analysis of docked results.Results: The docking studies show substrates bradykinin and substance-P bind near zinc binding site with minimum RMSD value and the inhibitors EDTA and lisinopril showed favorable interaction at zinc binding site of serrapeptidase with minimum free energy.Conclusion: The result of docking studies confirm that the substrate or inhibitor binds near zinc binding domain (HEXXH.) and the peptide bond of the substrate can be effectively cleaved by serrapeptidase.Keywords: Serrapeptidase, Anti-inflammation, Arthritis, Molecular docking, Drug discovery, Protein-peptide interaction, Bradykinin, Substance-

Structure-biological Activity Relationship of Analogues of 2-Chlorobenzylidenemalononitrile -A Riot-control Agent

The riot-control agent 2-chlorobenzylidenemalononitrile (CS) and its ortho-and parasubstituted benzylidenemalononitrile (BMN) analogues were synthesised and characterised by spectroscopic techniques (IR, NMR, and mass spectrometry) and microanalysis, and their structure-biological activity relationship studies were carried out to know the factors responsible for sensory irritation. Hydrophobicity of substituted BMNs were determined by high-performance liquid chromatography (HPLC), which is an important determinant of the irritancy. The vapour pressure of a compound is a physico-chemical property important for the assessment of its fate in the environment. The vapour pressures of BMNs were determined by static method by an isoteniscope. A systematic investigation of sensory irritation was carried out by evaluating decrease in respiratory rate (RDs,) in mice. The R.Dsi as biological parameter was correlated with physical parameters such as hydrophobicity, vapour pressure, size of molecules, and chemical reactivity of its BMNs with dimethylaminoethyl mercaptans (DEAEMs) as a simulant of protein-SH group. A biosignifkant correlation (0.75-0.80) was obtained.by correlating all the above parameters using multiple linear regression equation

Mechanical crystallization of Fe-based amorphous alloys

Mechanical alloying of a number of blended elemental powders of Fe-based alloy systems containing four or five components was undertaken to determine if amorphous phases could be produced and also to compare the glass-forming ability achieved by mechanical alloying and that obtained by solidification-processing methods. Amorphous phase formation was achieved in all the alloy systems investigated, the time for the amorphous phase formation being a function of the glass-forming ability of the alloy system investigated. However, in some alloy systems it was noted that on milling, beyond the time required for the formation of the amorphous phase, the amorphous phase started to crystallize, a phenomenon designated as mechanical crystallization. The present paper specifically discusses the results of mechanical crystallization obtained in the Fe42Ge28Zr10B20 and Fe42Ni28Zr10C10B10 alloy systems as representatives of the typical quaternary and quinary (five-component) systems, respectively. In the case of the quaternary system, mechanical crystallization led to the formation of a supersaturated solid solution of all the solute elements in Fe, while in the quinary system, a mixture of the solid solution and intermetallic phases has formed. The possible reasons for mechanical crystallization and the reasons for the differences in the behavior of the quaternary and quinary systems are discussed

Structure and glass-forming ability of simulated Ni-Zr alloys

Binary Cu-Zr system is a representative bulk glassformer demonstrating high glass forming ability due to pronounced icosahedral local ordering. From the first glance, Ni-Zr system is the most natural object to expect the same behavior because nickel and copper are neighbours in the periodic table and have similar physicochemical properties. However, doing molecular dynamics simulations of $\rm Ni_{\alpha}Zr_{1-\alpha}$ alloys described by embedded atom model potential, we observe different behaviour. We conclude that the Ni-Zr system has the same glass-forming ability as an additive binary Lennard-Jones mixture without any chemical interaction. The structural analysis reveals that icosahedral ordering in Ni-Zr alloys is much less pronounced than that in the Cu-Zr ones. We suggest that lack of icosahedral ordering due to peculiarities of interatomic interactions is the reason of relatively poor glass-forming ability of Ni-Zr system