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Search Results: 1 - 10 of 512982 matches for " A. I. Jaman "
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Millimeter-Wave Rotational Spectra of trans-Acrolein (Propenal) (CH2CHCOH): A DC Discharge Product of Allyl Alcohol (CH2CHCH2OH) Vapor and DFT Calculation
A. I. Jaman,Rangana Bhattacharya
Journal of Atomic, Molecular, and Optical Physics , 2012, DOI: 10.1155/2012/363247
Abstract: Millimeter-wave rotational spectrum of trans-acrolein (propenal) (CH2CHCOH) produced by applying a DC glow discharge through a low-pressure (~10–20 mTorr) flow of allyl alcohol (CH2CHCH2OH) vapor has been observed in the ground and several excited torsional states in the frequency region: 60.0–99.0 GHz. A least-square analysis of the measured and previously reported rotational transition frequencies has produced a set of rotational and centrifugal distortion constants for the ground as well as excited torsional states. Detailed DFT calculations were also carried out with various functional and basis sets to evaluate the spectroscopic constants, dipole moment, and various structural parameters of the trans conformer of propenal for the ground state and compared with their corresponding experimental values. A linear variation of the inertia defect values with torsional quantum number (=0,1,2,3) demonstrates that the equilibrium configuration of trans-propenal is planar.
Millimeter-Wave Rotational Spectrum, Barrier to Internal Rotation, and DFT Calculation of o-Tolunitrile
A. I. Jaman,P. Hemant Kumar,P. R. Bangal
Journal of Atomic, Molecular, and Optical Physics , 2011, DOI: 10.1155/2011/480396
Abstract: The millimeter-wave rotational spectra of o-tolunitrile (C6H4CH3CN) have been investigated in the ground torsional state in the frequency range 50.0–75.0 GHz. Many high-J rotational lines with large A-E splitting due to internal rotation of the methyl top have been assigned. A least squares analysis of the A-E splitting of 92 transitions resulted in the determination of accurate values of internal rotation parameters. The observed parameters were compared with the previously reported experimental values and DFT calculation results.
Millimeterwave Spectral Studies of Propynal (HCCCHO) Produced by DC Glow Discharge and Ab Initio DFT Calculation
A. I. Jaman,Rangana Bhattacharya,Debasish Mandal,Abhijit K. Das
Journal of Atomic, Molecular, and Optical Physics , 2011, DOI: 10.1155/2011/439019
Abstract: The ground-state (=0) millimeterwave rotational spectrum of propynal (HCCCHO) produced by a DC glow discharge through a low-pressure (~10–20 mTorr) flow of propargyl alcohol (HCCCH2OH) vapor has been observed in the frequency region: 36.0–94.0 GHz. Measured rotational transition frequencies along with the previously reported microwave and millimeterwave transitions were fitted to a standard asymmetric-top Hamiltonian to determine an improved set of rotational and centrifugal distortion constant. Detailed DFT calculations were also carried out with various functional and basis sets to evaluate the spectroscopic constants, dipole moment, and various structural parameters of propynal and compared with the corresponding experimental values.
Millimeter-Wave Rotational Spectrum, Barrier to Internal Rotation, and DFT Calculation of o-Tolunitrile
A. I. Jaman,P. Hemant Kumar,P. R. Bangal
Journal of Atomic and Molecular Physics , 2011, DOI: 10.1155/2011/480396
Abstract: The millimeter-wave rotational spectra of o-tolunitrile (C6H4CH3CN) have been investigated in the ground torsional state in the frequency range 50.0–75.0?GHz. Many high-J rotational lines with large A-E splitting due to internal rotation of the methyl top have been assigned. A least squares analysis of the A-E splitting of 92 transitions resulted in the determination of accurate values of internal rotation parameters. The observed parameters were compared with the previously reported experimental values and DFT calculation results. 1. Introduction The microwave rotational spectra of molecules having a methyl top attached to a planar frame shows a characteristic splitting corresponding to A and E symmetry of the torsional states. These A-E doublets may be closely or widely spaced depending on the height of the potential barrier and transitions studied. Hence, an analysis of the observed A-E splitting would lead to the determination of the barrier height hindering the internal rotation. Microwave spectroscopic techniques have been widely employed to study the effect of internal rotation of the methyl group on the rotational spectra of the molecules concerned. Extensive studies on the microwave [1–5] and electronic [6–8] spectra of toluene and substituted toluenes have been reported in the literature. In contrast, not much microwave spectroscopic work has been reported on tolunitriles. Fujii et al. [9] have investigated the fluorescence excitation and dispersed fluorescence spectra of o-, m-, and p-tolunitrile in supersonic jets. By analyzing the low-frequency bands due to internal rotation of the methyl group they have successfully determined the height of the potential barrier hindering the internal rotation for m- and p-tolunitrile. However, in the case of o-tolunitrile, the absence of low-frequency bands prevented them from determining the potential barrier. In an earlier communication, Jaman et al. [10] have reported the rotational constants and a value of the potential barrier from an analysis of the A-E splitting of the microwave spectrum of o-tolunitrile in the ground torsional state. Later, Hansen et al [11] have investigated the high-resolution microwave spectrum of o-tolunitrile by using molecular beam FT microwave spectroscopic technique and determined rotational, centrifugal distortion constants, 14N nuclear quadrupole hyperfine constants, as well as . The internal rotation parameters reported in [10, 11] were in good agreement with each other. In the present communication, we have extended the analysis of the microwave spectra of
Millimeterwave Spectral Studies of Propynal (HCCCHO) Produced by DC Glow Discharge and Ab Initio DFT Calculation
A. I. Jaman,Rangana Bhattacharya,Debasish Mandal,Abhijit K. Das
Journal of Atomic and Molecular Physics , 2011, DOI: 10.1155/2011/439019
Abstract: The ground-state ( ) millimeterwave rotational spectrum of propynal (HCCCHO) produced by a DC glow discharge through a low-pressure (~10–20?mTorr) flow of propargyl alcohol (HCCCH2OH) vapor has been observed in the frequency region: 36.0–94.0?GHz. Measured rotational transition frequencies along with the previously reported microwave and millimeterwave transitions were fitted to a standard asymmetric-top Hamiltonian to determine an improved set of rotational and centrifugal distortion constant. Detailed DFT calculations were also carried out with various functional and basis sets to evaluate the spectroscopic constants, dipole moment, and various structural parameters of propynal and compared with the corresponding experimental values. 1. Introduction Propynal (HCCCHO) also known as propiolic aldehyde has been found in interstellar molecular clouds TMC-1 and Sgr B2(N-LMH) [1–3]. In 1955 Howe and Goldstein [4] reported the and microwave transitions of the most abundant isotopic species of propynal. They have determined the dipole moment of the molecule to be D. Later on, Costain and Morton [5] determined the rotational constants , , and ( ) for the parent as well as various isotopic species and were able to determine an accurate substitution structure. Winnewisser [6] has extended the analysis of the ground state of propynal to the millimeterwave region (95.0–200.0?GHz) which has yielded a set of ground state rotational and centrifugal distortion constants. Reference [6] includes a set of predicted -type R-branch frequencies from 37.0 to 94.0?GHz covering to transitions which are of prime importance to radio astronomers for conducting search for this molecule in the interstellar space. Infrared-microwave double-resonance spectroscopic study of propynal using a Zeeman tuned He-Xe laser as the infrared source was conducted by Takami and Shimoda [7] to determine the rotational constants of the excited vibrational state. Later on, Jones [8] has reported the rotational constants of propynal in the ground as well as several excited state combination and hot bands using a CO2 laser as the infrared source. In all the previous works propynal was either procured commercially or prepared chemically. Production of new molecules, molecular ions, and radicals by applying a DC glow discharge through a low-pressure flow of gas or a mixture of gases inside an absorption cell has proved to be an efficient and useful technique [9]. Recently, Jaman [10] has reported an analysis of the millimeterwave rotational spectra of propyne (CH3CCH) produced by a DC glow discharge
Synthesis of 5-Substituted 2, 9-Dimethyl-1,10-Phenanthroline Dialdehydes and Their Schiff Bases with Sulfur-Containing Amines  [PDF]
Zinia Jaman, Mohammad R. Karim, Tasneem A. Siddiquee, Aminul H. Mirza, Mohamad A. Ali
International Journal of Organic Chemistry (IJOC) , 2013, DOI: 10.4236/ijoc.2013.33029
Abstract: Eight new Schiff bases of 5-nitro and 5-bromo-substituted 1,10-phenanthroline-2,9-dicarboxaldehydes with sulfur-containing amines, thiosemicarbazide, S-alkyl/aryl dithiocarbazates and 2-mercaptoaniline have been synthesized and characterized by a variety of spectroscopic methods. The condensation reactions of the dialdehydes with the amines were carried out both in the presence and absence of conc. sulfuric acid. A significant increase in yield of the Schiff bases was observed when the reactions were carried out in the presence of sulfuric acid.
Spore Micromorphology and Anatomy of the Fern GenusHistiopterisJ. Sm. (Dennstaedtiaceae) in Peninsular Malaysia
I. Faridah-Hanum,M.Z. Mustapa,Razali Jaman
International Journal of Botany , 2008,
Abstract: More recent classifications used mainly morphological data when Histiopteris was included as one of the genera in the family Dennstaedtiaceae. A study on spore micromorphological and anatomical studies of Histiopteris J. Sm. from Peninsular Malaysia was undertaken to provide spore micromorphological and anatomical information of the stipes, lamina and rhizomes for the genus. These information would become the source of reference and comparison for other members within the family Dennstaedtiaceae and would deem necessary in future classification considerations of Histiopteris when similar studies are carried out for all genera of the Dennstaedtiaceae in the near future.
The foraging behavior of Japanese macaques Macaca fuscata in a forested enclosure: Effects of nutrient composition, energy and its seasonal variation on the consumption of natural plant foods
M. Firoj JAMAN, Michael A. HUFFMAN, Hiroyuki TAKEMOTO
Current Zoology , 2010,
Abstract: In the wild, primate foraging behaviors are related to the diversity and nutritional properties of food, which are affected by seasonal variation. The goal of environmental enrichment is to stimulate captive animals to exhibit similar foraging behavior of their wild counterparts, e.g. to extend foraging time. We conducted a 12-month study on the foraging behavior of Japanese macaques in a semi-naturally forested enclosure to understand how they use both provisioned foods and naturally available plant foods and what are the nutritional criteria of their consumption of natural plants. We recorded time spent feeding on provisioned and natural plant foods and collected the plant parts ingested of their major plant food species monthly, when available. We conducted nutritional analysis (crude protein, crude lipid, neutral detergent fiber-‘NDF’, ash) and calculated total non-structural carbohydrate – ‘TNC’ and total energy of those food items. Monkeys spent 47% of their feeding time foraging on natural plant species. The consumption of plant parts varied significantly across seasons. We found that leaf items were consumed in months when crude protein, crude protein-to-NDF ratio, TNC and total energy were significantly higher and NDF was significantly lower, fruit/nut items in months when crude protein and TNC were significantly higher and crude lipid content was significantly lower, and bark items in months when TNC and total energy were higher and crude lipid content was lower. This preliminary investigation showed that the forested enclosure allowed troop members to more fully express their species typical flexible behavior by challenging them to adjust their foraging behavior to seasonal changes of plant item diversity and nutritional content, also providing the possibility for individuals to nutritionally enhance their diet [Current Zoology 56 (2): 198–208, 2010].
Antibacterial Activities of New Schiff Bases and Intermediate Silyl Compounds Synthesized from 5-Substituted-1,10-phenanthroline- 2,9-dialdehyde  [PDF]
Zinia Jaman, Mohammad R. Karim, Korsi Dumenyo, Aminul H. Mirza
Advances in Microbiology (AiM) , 2014, DOI: 10.4236/aim.2014.415124
Abstract: Schiff bases are known to possess anticancer, antibacterial, antifungal, antitubercular, anti-inflammatory, antimicrobial and antimalarial properties. In this paper antibacterial studies against variety of plants and human pathogenic bacteria with eight newly synthesized Schiff bases and several intermediate silyl compounds have been reported. The antibacterial activities of the synthesized compounds were primarily determined by paper disc diffusion method. The minimum inhibitory concentration (MIC) of each compound was also determined by tube dilution process. Seven different human pathogenic bacteria and eighteen different plant pathogenic bacteria were used for the antibacterial activity studies. While all synthesized compounds have shown significant antibacterial activity, one intermediate silyl compound has shown remarkably high antibacterial property. 5-substituted derivatives have shown relatively higher activity than non-substituted compounds. Polar substituent which increases hydrophilicity may have a positive impact on the antibacterial property.
CROSSTALK ANALYSIS OF A FBG-OC BASED OPTICAL ADD-DROP MULTIPLEXER FOR WDM CROSSCONNECTS SYSTEM
Nahian Chowdhury,Shahid Jaman,Rubab Amin,Md. Sadman Sakib Chowdhury
International Journal of Advances in Engineering and Technology , 2012,
Abstract: Theoretical analysis and numerical simulation is carried out to evaluate the performance of an Optical Add-drop multiplexer (OADM) for Wavelength Division Multiplexing (WDM) transmission system in the presence of linear crosstalk due to Fiber Bragg Gratings (FBGs) and optical circulator (OC) which can be used in Optical Crossconnects. We analyzed here the add drop multiplexing system for multiple wavelength channels, different condition of channel presence and channel separation. We simulate the crosstalk power, signal-to crosstalk ratio (SCR) and bit error rate (BER) of the system with different number of channels presence. Here we compared crosstalk power and SCR for multiple wavelength channels like 4, 8, 16, 32 channels considering different channel separation and drop of channels from the system. It is found that the SCR increases with the channel separation and SCR decreases with increase of the channel Bandwidth (B). BER increases with the number of wavelength channels due to increased in amount of crosstalk.
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