Biofilm Formation and Indole-3-Acetic Acid Production by Two Rhizospheric Unicellular Cyanobacteria

( Mehboob Ahmed ),( Lucas J Stal ),( Shahida Hasnain ) 한국미생물 · 생명공학회 2014 Journal of microbiology and biotechnology Vol.24 No.8

Microorganisms that live in the rhizosphere play a pivotal role in the functioning and maintenance of soil ecosystems. The study of rhizospheric cyanobacteria has been hampered by the difficulty to culture and maintain them in the laboratory. The present work investigated the production of the plant hormone indole-3-acetic acid (IAA) and the potential of biofilm formation on the rhizoplane of pea plants by two cyanobacterial strains, isolated from rice rhizosphere. The unicellular cyanobacteria Chroococcidiopsis sp. MMG-5 and Synechocystis sp. MMG-8 that were isolated from a rice rhizosphere, were investigated. Production of IAA by Chroococcidiopsis sp. MMG-5 and Synechocystis sp. MMG-8 was measured under experimental conditions (pH and light). The bioactivity of the cyanobacterial auxin was demonstrated through the alteration of the rooting pattern of Pisum sativum seedlings. The increase in the concentration of L-tryptophan and the time that this amino acid was present in the medium resulted in a significant enhancement of the synthesis of IAA (r > 0.900 at p = 0.01). There was also a significant correlation between the concentration of IAA in the supernatant of the cyanobacteria cultures and the root length and number of the pea seedlings. Observations made by confocal laser scanning microscopy revealed the presence of cyanobacteria on the surface of the roots and also provided evidence for the penetration of the cyanobacteria in the endorhizosphere. We show that the synthesis of IAA by Chroococcidiopsis sp. MMG-5 and Synechocystis sp. MMG-8 occurs under different environmental conditions and that the auxin is important for the development of the seedling roots and for establishing an intimate symbiosis between cyanobacteria and host plants.

Mass Minimization by Selecting Proper Material and Shape Aided by Dynamic Analyses and Verified Via Finite Element Method

Behzad Ahmed Zai,M.K. Park,Rashid Ali Sindhu,Joongwon Lee,Hassan Mehboob 한국자동차공학회 2008 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-

Mass minimization is considered one of the most important factors for design of mechanical structures applied particularly for aerospace structures, which can be obtained through a proper selection of materials and shape optimization. In this paper a numerical method is applied for this purpose and then verified via a finite element method using ANSYS which enables stress constraints to be optimized based on the local Von Mises stresses. A cantilever beam is selected as a mechanical structure for simplicity of its calculation. Structural optimization involves creating geometry which allows parametric study of all design variables and through optimization scheme iteratively selecting the optimum shape. The cross-sections of square and circular were compared together for mass minimization. Estimation of dynamic characteristics of a structure often leads to difference between success and failure due to resonance effect, therefore in order to predict a structural vibration transient and harmonic analyses are performed simultaneously in this paper for the tip displacement and reaction forces in time domain and for the varying excitation frequencies of the applied load. The results found are very useful for many applications particularly where the dynamic loading is invertible.

Effect of moisture absorption on damping and dynamic stiffness of carbon fiber/epoxy composites

Behzad Ahmed Zai,박명균,H. S. Choi,Hassan Mehboob,Rashid Ali 대한기계학회 2009 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.23 No.11

In this paper, the damping and dynamic stiffness of UHN125C carbon fiber/epoxy composite beam was experimentally measured. The effect of fiber orientation angle and stacking sequences on damping, resonance frequency, and dynamic stiffness was discussed with a focus on the effect of moisture absorption. Dried specimens were immersed in distilled water for a certain period to absorb water for 8, 16, and 24 d, respectively, and the moisture content absorbed in the specimen was measured. Furthermore, using the impact hammer technique, the measurements of dynamic responses were conducted on a cantilever beam specimen with one end clamped by bolts and metal plates. The damping properties in terms of loss factor were approximated by half-power bandwidth technique. The dynamic stiffness was evaluated using resonance frequency as a function of moisture content. The damping increased with the increase of moisture content; however, the dynamic stiffness reduced with the reduction of resonance frequency. The results of the dynamic stiffness were aided by measuring the dynamic strain using DBU-120A strain-indicating software. The increment in the dynamic strain strengthened the results obtained for dynamic stiffness.

Molecular Identification and Characterization of Pseudomonas sp. NCCP-407 for Phenol Degradation Isolated From Industrial Waste

Ahmad, Nazir,Ahmed, Iftikhar,Shahzad, Armghan,Khalid, Nauman,Mehboob, Farrakh,Ahad, Karam,Ali, Ghulam Muhammad The Korean Society for Applied Biological Chemistr 2014 Applied Biological Chemistry (Appl Biol Chem) Vol.57 No.3

Phenol is a toxic pollutant found in effluent of numerous industries and its elimination is a foremost challenge. The utilization of bacteria plays a crucial role in phenol bioremediation. For isolation of phenol degrading bacteria, sample was collected from industrial waste and enriched in mineral salt medium (MSM) contained 300 mg/L phenol. The strain was identified based on 16S rRNA gene analysis as Pseudomonas species and the phylogenetic analysis affiliated the strain with Pseudomonas monteilii (AF064458) as the most closely related species. Phenol tolerance of the strain in MSM supplemented with various concentrations of phenol indicates that the strain NCCP-407 can grow best at $750mgL^{-1}$ phenol. The strain showed complete degradation of $750mgL^{-1}$ phenol in 56 hours when supplement as a sole source of carbon and energy with the average degradation rate of $28mgL^{-1}h^{-1}$. The doubling time was recorded approximately as $12.49h^{-1}$. The present study suggests that this strain is efficient in phenol degradation and can be used in treatment of wastewater containing phenol.

Molecular Identification and Characterization of Pseudomonas sp. NCCP-407 for Phenol Degradation Isolated From Industrial Waste

Nazir Ahmad,Iftikhar Ahmed,Armghan Shahzad,Nauman Khalid,Farrakh Mehboob,Karam Ahad,Ghulam Muhammad Ali 한국응용생명화학회 2014 Applied Biological Chemistry (Appl Biol Chem) Vol.57 No.3

Phenol is a toxic pollutant found in effluent ofnumerous industries and its elimination is a foremost challenge. The utilization of bacteria plays a crucial role in phenol bioremediation. For isolation of phenol degrading bacteria, sample was collectedfrom industrial waste and enriched in mineral salt medium (MSM)contained 300 mg/L phenol. The strain was identified based on16S rRNA gene analysis as Pseudomonas species and thephylogenetic analysis affiliated the strain with Pseudomonasmonteilii (AF064458) as the most closely related species. Phenoltolerance of the strain in MSM supplemented with variousconcentrations of phenol indicates that the strain NCCP-407 cangrow best at 750 mg L−1 phenol. The strain showed completedegradation of 750 mg L−1 phenol in 56 hours when supplementas a sole source of carbon and energy with the average degradationrate of 28mg L−1 h−1. The doubling time was recorded approximatelyas 12.49 h−1. The present study suggests that this strain is efficientin phenol degradation and can be used in treatment of wastewatercontaining phenol.

A Residual Stress Evaluation in Laser Welded Lap Joint with Hole Drilling Method

박명균,이수진,Behzad Ahmed Zai,Hassan Mehboob,Rashid Ali Sindhu 한국정밀공학회 2009 International Journal of Precision Engineering and Vol.10 No.5

Residual stresses deteriorate strength of materials affecting the quality of industrial products. A removal or reduction of the residual stresses is an essential procedure in successful engineering component development. Effective and convenient methods are necessary for detection and evaluation of residual stresses. In this paper Hole Drilling Method is chosen for identification and a quantitative determination of the residual stresses in specimens of two groups under different laser welding speed conditions, 4.1m/min and 5.1m/min. The lap joints welded with STS 301L sheet of two different speeds were investigated along the welding line at two locations, the middle and the end location in the heat affected zone (HAZ). The identification of HAZ is carried out by taking hardness values from weld centerline to the raw material. Based on the experimental results and analysis, it is found that higher welding speed reduces the residual stresses. Also, the end location is found to be higher residual stress area compared with middle location due to the convective boundary condition. The residual stresses decrease as the depth increases from the top surface due to the lower heat input to depth increments.

Quantification of Residual Stresses in Laser Welded Cold Rolled Steel Sheets with Hole Drilling Method

Rashid Ali Sindhu,M.K.Park,Saemahn Bhak,Behzad Ahmed Zai,Hassan Mehboob,Joongwon Lee 한국자동차공학회 2008 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-

Residual stresses deteriorate strength of materials adversely affecting quality of industrial products. A removable or a reduction of the residual stresses is an essential procedure in successful product developments. Effective and convenient methods are necessary for detection and evaluation of the residual stresses. In this investigation Hole Drilling Method is chosen for identification and a quantitative determination of the residual stresses of specimen in two groups under different laser welding speed conditions, 4.1 m/min and 5.1 m/min. Laser lap welding of SPCC sheet joints was investigated along the welding line at two locations, at the welding middle and end locations in the heat affected zone (HAZ). Based on the experimental results and the analysis, higher welding speed condition is predicted to reduce the residual stresses.