ARTICLES YOU MAY BE INTERESTED IN Mechanisms of low-frequency dielectric barrier discharge (DBD) ... more ARTICLES YOU MAY BE INTERESTED IN Mechanisms of low-frequency dielectric barrier discharge (DBD) plasma driven by unipolar pulses and bipolar pulses AIP Advances 11, 025022 (2021);
Madagascar is home to many endemic plant and animal species owing to its ancient isolation from o... more Madagascar is home to many endemic plant and animal species owing to its ancient isolation from other landmasses. This unique fauna includes several lineages of termites, a group of insects known for their key role in organic matter decomposition in many terrestrial ecosystems. How and when termites colonised Madagascar remains unknown. In this study, we used 601 mitochondrial genomes, 93 of which were generated from Madagascan samples, to infer the global historical biogeography of Neoisoptera, a lineage containing upwards of 80% of described termite species. Our results indicate that Neoisoptera colonised Madagascar between seven to ten times independently during the Miocene, between 8.4-16.6 Ma (95% HPD: 6.1-19.9 Ma). This timing matches that of the colonization of Australia by Neoisoptera. Furthermore, the taxonomic composition of the Neoisopteran fauna of Madagascar and Australia are strikingly similar, with Madagascar harbouring an additional two lineages absent from Australia...
Termites are social cockroaches distributed throughout warm temperate and tropical ecosystems. Th... more Termites are social cockroaches distributed throughout warm temperate and tropical ecosystems. The ancestor of modern termites (crown-Isoptera) occurred during the earliest Cretaceous, approximately 140 million years ago, suggesting that both vicariance through continental drift and overseas dispersal may have shaped the distribution of early diverging termite lineages. We reconstruct the historical biogeography of three early diverging termite families – Stolotermitidae, Hodotermitidae, and Archotermopsidae – using the nuclear rRNA genes and mitochondrial genomes of 27 samples. Our analyses confirmed the monophyly of Stolotermitidae + Hodotermitidae + Archotermopsidae (clade Teletisoptera), with Stolotermitidae diverging from a monophyletic Hodotermitidae + Archotermopsidae approximately 100.3 Ma (94.3–110.4 Ma, 95% HPD), and with Archotermopsidae paraphyletic to a monophyletic Hodotermitidae. The Oriental Archotermopsis and the Nearctic Zootermopsis diverged 50.8 Ma (40.7–61.4 Ma,...
Abstract With a bipolar pulse power, wear-resistant ceramic coatings with high micro-hardness wer... more Abstract With a bipolar pulse power, wear-resistant ceramic coatings with high micro-hardness were in-situ fabricated on 2A50 aluminum alloy using micro-arc oxidation method in silicate electrolyte. The effect of cathodic voltage on microstructure, phase structure, micro-hardness and wear properties was investigated by changing cathodic voltage from 0 to −200 V. The phase structure, microstructure, micro-hardness and wear resistance were determined by XRD, SEM, HVS-1000 Vicker's micro-hardness tester and tribology tester. The results show that the phase of the obtained coatings is mainly composed of γ-Al2O3. The coating consists of the inner dense layer and the outer loose layer. As the cathodic voltage increases, the quantity and size of the micro-pores in the coatings first decrease and then increase. Micro-arc oxidation can greatly strengthen 2A50 aluminum alloy, the micro-hardness increases from 75 HV0.5 to 1321 HV0.5 after a micro-arc oxidation under a cathodic voltage of −100 V. The friction coefficient of the ceramic coatings are in the range of 0.35–0.55, and the coating obtained under −100 V exhibits the best wear resistance. The wear mechanism is deduced to be the combination of abrasive and adhesive wear.
Floral colour change is visual signals for pollinators to avoid old flowers and increase pollinat... more Floral colour change is visual signals for pollinators to avoid old flowers and increase pollination efficiency. Quisqualis indica flowers change colour from white to pink to red may be associated with a shift from moth to butterfly pollination. To test this hypothesis, we investigated Q. indica populations in Southwest China. Flowers secreted nectar continuously from the evening of anthesis until the following morning, then decreased gradually with floral colour change. The scent compounds in the three floral colour stages were similar; however, the scent composition was different, and the scent emission rate decreased from the white to red stage. Dichogamy in Q. indica prevents self-pollination and interference of male and female functions. Controlled pollinations demonstrated that this species is self-incompatible and needs pollinators for seed production. Different pollinators were attracted in each floral colour stage; mainly moths at night and bees and butterflies during the d...
Post-tensioned box girder bridges are considered one of the most structurally efficient bridge sy... more Post-tensioned box girder bridges are considered one of the most structurally efficient bridge systems and are widely used in the U.S. This study investigates numerical results of progressive collapse for post-tensioned box girder bridges under blast loads. Limited data is published on this topic; however there is available literature on the analysis of the progressive collapse of cable-stayed bridges under blast loads. Accidental detonations are assumed to take place under the bridge deck. Numerical simulation is conducted using the Applied Element Method implemented in "Extreme Loading for Structures" software. The numerical model of the bridge structure and simulation results of the main bridge components, piers, and main span deck are investigated. The parameter studied was in terms of the weight of the explosion at two different locations simulating a large vehicle bomb (LVB) placed underneath the bridge. The progressive collapse analyses of the bridge structure after damage in either one of the two main bridge components are investigated. Damage mechanism and severity in the bridge pier, and deck are examined. Numerical results presented in this study could help departments of transportation and engineers and owners of similar bridges to determine appropriate measures for bridge protection against possible explosion threats.
2014 3rd International Conference on User Science and Engineering (i-USEr), 2014
Conventional way of teaching Chemistry in high school is boring and not interesting enough to dev... more Conventional way of teaching Chemistry in high school is boring and not interesting enough to develop the student's interest in this field. Despite the advancement of interactive multimedia, which heavily impacts the age group from 16 to 24 years old, the technology has not been implemented progressively in the educational field. This paper presents the development of a mobile game-based tutorial for learning Chemistry. A field study using the survey approach was conducted among 40 students in order to determine the difficulty of Chemistry sub-topics and appropriate genres for the game. The mobile game-based learning was then developed using Eclipse and Android Development Kit. Later, a usability test using the User Experience Test (UX) approach was conducted with 6 respondents in determining the level of the usability achievement of the game. The results showed that the respondents were satisfied with the game. It is hoped that the game will be able to assist the students in learning Chemistry.
ARTICLES YOU MAY BE INTERESTED IN Mechanisms of low-frequency dielectric barrier discharge (DBD) ... more ARTICLES YOU MAY BE INTERESTED IN Mechanisms of low-frequency dielectric barrier discharge (DBD) plasma driven by unipolar pulses and bipolar pulses AIP Advances 11, 025022 (2021);
Madagascar is home to many endemic plant and animal species owing to its ancient isolation from o... more Madagascar is home to many endemic plant and animal species owing to its ancient isolation from other landmasses. This unique fauna includes several lineages of termites, a group of insects known for their key role in organic matter decomposition in many terrestrial ecosystems. How and when termites colonised Madagascar remains unknown. In this study, we used 601 mitochondrial genomes, 93 of which were generated from Madagascan samples, to infer the global historical biogeography of Neoisoptera, a lineage containing upwards of 80% of described termite species. Our results indicate that Neoisoptera colonised Madagascar between seven to ten times independently during the Miocene, between 8.4-16.6 Ma (95% HPD: 6.1-19.9 Ma). This timing matches that of the colonization of Australia by Neoisoptera. Furthermore, the taxonomic composition of the Neoisopteran fauna of Madagascar and Australia are strikingly similar, with Madagascar harbouring an additional two lineages absent from Australia...
Termites are social cockroaches distributed throughout warm temperate and tropical ecosystems. Th... more Termites are social cockroaches distributed throughout warm temperate and tropical ecosystems. The ancestor of modern termites (crown-Isoptera) occurred during the earliest Cretaceous, approximately 140 million years ago, suggesting that both vicariance through continental drift and overseas dispersal may have shaped the distribution of early diverging termite lineages. We reconstruct the historical biogeography of three early diverging termite families – Stolotermitidae, Hodotermitidae, and Archotermopsidae – using the nuclear rRNA genes and mitochondrial genomes of 27 samples. Our analyses confirmed the monophyly of Stolotermitidae + Hodotermitidae + Archotermopsidae (clade Teletisoptera), with Stolotermitidae diverging from a monophyletic Hodotermitidae + Archotermopsidae approximately 100.3 Ma (94.3–110.4 Ma, 95% HPD), and with Archotermopsidae paraphyletic to a monophyletic Hodotermitidae. The Oriental Archotermopsis and the Nearctic Zootermopsis diverged 50.8 Ma (40.7–61.4 Ma,...
Abstract With a bipolar pulse power, wear-resistant ceramic coatings with high micro-hardness wer... more Abstract With a bipolar pulse power, wear-resistant ceramic coatings with high micro-hardness were in-situ fabricated on 2A50 aluminum alloy using micro-arc oxidation method in silicate electrolyte. The effect of cathodic voltage on microstructure, phase structure, micro-hardness and wear properties was investigated by changing cathodic voltage from 0 to −200 V. The phase structure, microstructure, micro-hardness and wear resistance were determined by XRD, SEM, HVS-1000 Vicker's micro-hardness tester and tribology tester. The results show that the phase of the obtained coatings is mainly composed of γ-Al2O3. The coating consists of the inner dense layer and the outer loose layer. As the cathodic voltage increases, the quantity and size of the micro-pores in the coatings first decrease and then increase. Micro-arc oxidation can greatly strengthen 2A50 aluminum alloy, the micro-hardness increases from 75 HV0.5 to 1321 HV0.5 after a micro-arc oxidation under a cathodic voltage of −100 V. The friction coefficient of the ceramic coatings are in the range of 0.35–0.55, and the coating obtained under −100 V exhibits the best wear resistance. The wear mechanism is deduced to be the combination of abrasive and adhesive wear.
Floral colour change is visual signals for pollinators to avoid old flowers and increase pollinat... more Floral colour change is visual signals for pollinators to avoid old flowers and increase pollination efficiency. Quisqualis indica flowers change colour from white to pink to red may be associated with a shift from moth to butterfly pollination. To test this hypothesis, we investigated Q. indica populations in Southwest China. Flowers secreted nectar continuously from the evening of anthesis until the following morning, then decreased gradually with floral colour change. The scent compounds in the three floral colour stages were similar; however, the scent composition was different, and the scent emission rate decreased from the white to red stage. Dichogamy in Q. indica prevents self-pollination and interference of male and female functions. Controlled pollinations demonstrated that this species is self-incompatible and needs pollinators for seed production. Different pollinators were attracted in each floral colour stage; mainly moths at night and bees and butterflies during the d...
Post-tensioned box girder bridges are considered one of the most structurally efficient bridge sy... more Post-tensioned box girder bridges are considered one of the most structurally efficient bridge systems and are widely used in the U.S. This study investigates numerical results of progressive collapse for post-tensioned box girder bridges under blast loads. Limited data is published on this topic; however there is available literature on the analysis of the progressive collapse of cable-stayed bridges under blast loads. Accidental detonations are assumed to take place under the bridge deck. Numerical simulation is conducted using the Applied Element Method implemented in "Extreme Loading for Structures" software. The numerical model of the bridge structure and simulation results of the main bridge components, piers, and main span deck are investigated. The parameter studied was in terms of the weight of the explosion at two different locations simulating a large vehicle bomb (LVB) placed underneath the bridge. The progressive collapse analyses of the bridge structure after damage in either one of the two main bridge components are investigated. Damage mechanism and severity in the bridge pier, and deck are examined. Numerical results presented in this study could help departments of transportation and engineers and owners of similar bridges to determine appropriate measures for bridge protection against possible explosion threats.
2014 3rd International Conference on User Science and Engineering (i-USEr), 2014
Conventional way of teaching Chemistry in high school is boring and not interesting enough to dev... more Conventional way of teaching Chemistry in high school is boring and not interesting enough to develop the student's interest in this field. Despite the advancement of interactive multimedia, which heavily impacts the age group from 16 to 24 years old, the technology has not been implemented progressively in the educational field. This paper presents the development of a mobile game-based tutorial for learning Chemistry. A field study using the survey approach was conducted among 40 students in order to determine the difficulty of Chemistry sub-topics and appropriate genres for the game. The mobile game-based learning was then developed using Eclipse and Android Development Kit. Later, a usability test using the User Experience Test (UX) approach was conducted with 6 respondents in determining the level of the usability achievement of the game. The results showed that the respondents were satisfied with the game. It is hoped that the game will be able to assist the students in learning Chemistry.
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Papers by Haikal Rahman