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11. Circular RNA and Alzheimer’s Disease

Author

Akhter, Rumana, COHEN, IRUN R., Series Editor, LAJTHA, ABEL, Series Editor, LAMBRIS, JOHN D., Series Editor, PAOLETTI, RODOLFO, Series Editor, Rezaei, Nima, Series Editor, and Xiao, Junjie, editor

Published
2018
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17. Microstructure, Mechanical and Tribological Properties of Ternary Transition Metal Nitride Coatings

Author

Akhter, Rumana

Subjects
TMN coatings, Wear Resistance, 4016 Materials engineering, Mechanical Properties, Microstructures, Deformation Behaviour
Abstract

The evolution of transition metal nitride (TMN) coatings with excellent mechanical and tribological properties has been shown to be a successful strategy in protecting tool components. In this thesis, the microstructure, mechanical properties and tribological performances of a range of TMN-based coatings, synthesised by physical vapor deposition techniques, were explored. First, the influence of substrate bias, on the structure and properties of magnetron sputtered TiSiN coatings was investigated. Enhanced scratch resistance i.e., higher critical loads (Lc1 and Lc2) was found in the coating deposited at the lower bias voltage (-40 V), which was ascribed to higher H/Er and H3/Er 2 ratios arising from fine nanocomposite structure and the presence of a higher compressive residual stress. An approximately 21% increase in wear rate was obtained for the coating prepared at higher bias (-50 V), which was attributed to slightly higher Si concentrations (~9.4 at.%) and, in turn, lower hardness. Further, a notable increase in Lc1 (~54%) and Lc2 (~27%) values, was obtained for a thick TiSiN coating (magnetron sputtered at a different condition) in comparison to the binary TiN coating that were underlain by its superior mechanical properties and graded structure, promoting the capacity to resist crack formation and delamination. Furthermore, the influence of Ni content, regulated by cathode composition, on the structure and properties of cathodic arc evaporated TiNiN coatings was examined. A transition from a fine columnar structure, at low Ni contents (~2 at.%), to a much finer equiaxed structure at higher Ni concentrations (≥ 4 at.%) was noted. In addition, the density of macroparticles generated during arcing was shown to be inversely related to the melting temperature of the target material. Finally, the effect of Ni content, controlled by the NiCr target current (INiCr) on the structure mechanical properties and scratch and wear behaviour of magnetron sputtered CrNiN coatings was studied. Significant damage-tolerance, coupled with good hardness values (greater than ~12 GPa), was found in the CrNiN coatings deposited at INiCr ≥2 A. The presence of a metallic nickel-rich phase, together with nanoscale porosity, may contribute to stress dissipation and help maintain structural integrity.

Published
2021
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30. A possible alternative therapy for type 2 diabetes using Myristica fragransHoutt in combination with glimepiride: in vivo evaluation and in silico support

Author

Nasreen, Waheeda, Sarker, Suchitra, Sufian, Md. Abu, Md. Opo, F.A. Dain, Shahriar, Mohammad, Akhter, Rumana, and Halim, Mohammad A.

Abstract

The current study aimed to evaluate the in vivo hypoglycemic potential of Myristica fragransseed extract co-administered with glimepiride in Swiss albino mice. Computational tools were used to further verify the in vivo findings and to help compare this combination to the glimepiride-pioglitazone combination in terms of the binding affinity of the ligands to their respective target protein receptors and the relative stability of the drug-protein complexes. The effect of the combined therapy was observed both in alloxan- and glucose-induced hyperglycemic Swiss albino mice. The mean fasting blood glucose level of the test groups was measured and statistically evaluated using Student’s t test. The combined therapy significantly reduced the blood glucose level in a time-dependent manner compared to glimepiride alone. The binding affinity of glimepiride was found to be −7.6 kcal/mol with sulfonylurea receptor 1 in molecular docking. Conversely, macelignan-peroxisome proliferator-activated receptor (PPAR) α and macelignan-PPAR γ complexes were stabilized with −9.2 and −8.3 kcal/mol, respectively. Molecular dynamic simulation revealed that macelignan-PPAR α and γ complexes were more stable than pioglitazone complexes. The combination shows promise in animal and computer models and requires further trials to provide evidence of its activity in humans.

Published
2020
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41. General observation, cognition, emotion, social, communication, sensory deficiency of autistic children.

Author

Alam, Sabrina Shajeen, Kabir, Syed Md. Sajjad, and Akhter, Rumana

Subjects
COGNITION research, EMOTIONS, AUTISTIC children, PERVASIVE child development disorders, AUTISM in children
Abstract

One of the prominent determinants to recognize someone has autism is impairment in some specific dimensions. They live in their own virtual world which is separate from the actual world. They have to go in the process of learning how to cope with, adapt, and relate to others and the world around them. The aim of the present study was to explore the degree of autistic children in Chittagong city of Bangladesh. For this purpose 115 already diagnosed autistic children aged from 3 to 16 years old were selected. The used instrument was Autistic Diagnostic Check List (Dr.Mallika Banerjee, 2007). There were 60 items which were categorized in six sub-groups, namely general observation, cognition, emotion, social, communication, sensory deficiency. Among the 115 children, 56 autistic children were in normal range and only 2 children were in severe range. Among them 73 were boys and 42 were girls and their mean scores for six sub-groups did not differ significantly. Finally, the six sub-groups seemed to be uniformly important in the understanding of autism symptoms. [ABSTRACT FROM AUTHOR]

Published
2015

43. Microstructure, Mechanical and Tribological Properties of Ternary Transition Metal Nitride Coatings

Author

Akhter, Rumana ; https://orcid.org/0000-0002-4850-0739

Subjects
TMN coatings, Microstructures, Mechanical Properties, Wear Resistance, Deformation Behaviour, anzsrc-for: 4016 Materials engineering
Abstract

The evolution of transition metal nitride (TMN) coatings with excellent mechanical and tribological properties has been shown to be a successful strategy in protecting tool components. In this thesis, the microstructure, mechanical properties and tribological performances of a range of TMN-based coatings, synthesised by physical vapor deposition techniques, were explored. First, the influence of substrate bias, on the structure and properties of magnetron sputtered TiSiN coatings was investigated. Enhanced scratch resistance i.e., higher critical loads (Lc1 and Lc2) was found in the coating deposited at the lower bias voltage (-40 V), which was ascribed to higher H/Er and H3/Er 2 ratios arising from fine nanocomposite structure and the presence of a higher compressive residual stress. An approximately 21% increase in wear rate was obtained for the coating prepared at higher bias (-50 V), which was attributed to slightly higher Si concentrations (~9.4 at.%) and, in turn, lower hardness. Further, a notable increase in Lc1 (~54%) and Lc2 (~27%) values, was obtained for a thick TiSiN coating (magnetron sputtered at a different condition) in comparison to the binary TiN coating that were underlain by its superior mechanical properties and graded structure, promoting the capacity to resist crack formation and delamination. Furthermore, the influence of Ni content, regulated by cathode composition, on the structure and properties of cathodic arc evaporated TiNiN coatings was examined. A transition from a fine columnar structure, at low Ni contents (~2 at.%), to a much finer equiaxed structure at higher Ni concentrations (≥ 4 at.%) was noted. In addition, the density of macroparticles generated during arcing was shown to be inversely related to the melting temperature of the target material. Finally, the effect of Ni content, controlled by the NiCr target current (INiCr) on the structure mechanical properties and scratch and wear behaviour of magnetron sputtered CrNiN coatings was studied. Significant damage-tolerance, coupled with good hardness values (greater than ~12 GPa), was found in the CrNiN coatings deposited at INiCr ≥2 A. The presence of a metallic nickel-rich phase, together with nanoscale porosity, may contribute to stress dissipation and help maintain structural integrity.

Published
2021

44. Enhancing the adhesion strength and wear resistance of nanostructured NiCrN coatings

Author

<p>Australian Government Research Training Program Scholarship Australian Research Council Discovery Project</p>, Akhter, Rumana, Zhou, Zhifeng, Xie, Zonghan, Munroe, Paul, <p>Australian Government Research Training Program Scholarship Australian Research Council Discovery Project</p>, Akhter, Rumana, Zhou, Zhifeng, Xie, Zonghan, and Munroe, Paul

Abstract

Akhter, R., Zhou, Z., Xie, Z., & Munroe, P. (2021). Enhancing the adhesion strength and wear resistance of nanostructured NiCrN coatings. Applied Surface Science, 541, article 148533. https://doi.org/10.1016/j.apsusc.2020.148533

45. Harmonizing mechanical responses of nanostructured CrN coatings via Ni additions

Author

<p>Australian Government Research Training Program Scholarship</p>, Akhter, Rumana, Zhou, Zhifeng, Xie, Zonghan, Munroe, Paul, <p>Australian Government Research Training Program Scholarship</p>, Akhter, Rumana, Zhou, Zhifeng, Xie, Zonghan, and Munroe, Paul

Abstract

Akhter, R., Zhou, Z., Xie, Z., & Munroe, P. (2021). Harmonizing mechanical responses of nanostructured CrN coatings via Ni additions. Applied Surface Science, 538, article 147987. https://doi.org/10.1016/j.apsusc.2020.147987

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