CHINMOY Das - Academia.edu (original) (raw)
Papers by CHINMOY Das
IP International Journal of Orthopaedic Rheumatology
A group of inflammatory arthritic disorders known as juvenile idiopathic arthritis (JIA) are char... more A group of inflammatory arthritic disorders known as juvenile idiopathic arthritis (JIA) are characterized by arthritis of uncertain origin that first manifests in a child under the age of 16. This is the most common chronic rheumatological disease of childhood. The JIA is present in every country and has an incidence of 1 in 100,000. Despite the absence of a documented etiology, there are a number of genetic and environmental risk factors as well as immunologic abnormalities that can be seen and used to infer information about the pathophysiology of the illness. Although there is no cure, modern therapy can frequently reduce the underlying inflammation and enhance function and symptoms. In this case patient showed complete resolution of symptoms with no signs of recurrence. As a result, it helps patient to live a healthy life.
Inorganic Chemistry, 2018
Controlling quantum tunneling of magnetization (QTM) is a persistent challenge in lanthanide-base... more Controlling quantum tunneling of magnetization (QTM) is a persistent challenge in lanthanide-based single-molecule magnets. As the exchange interaction is one of the key factors in controlling the QTM, we targeted lanthanide complexes with an increased number of radicals around the lanthanide ion. On the basis of our targeted approach, a family of pseudo-octahedral lanthanide/transition-metal complexes were isolated with the general molecular formula of [M(L •−) 3 ] (M = Gd (1), Dy (2), Er (3), Y (4)) using the redox-active iminopyridyl (L •−) ligand exclusively, which possess the highest ratio of radicals to lanthanide reported for discrete metal complexes. Direct current magnetic susceptibility studies suggest that dominant antiferromagnetic interactions exist between the radical and lanthanide ions in all of the complexes, which is strongly corroborated by magnetic data fitting using a Heisenberg−Dirac−Van Vleck (HDVV) Hamiltonian (−2J Hamiltonian). A good agreement between the fit and the experimental magnetic data obtained using g = 2, J rad-rad = −111.9 cm −1 for 4 and g = 1.99, J rad-rad = −111.9 cm −1 , J Gd-rad = −1.85 cm −1 for 1. Complex 2 shows frequency-dependent slow magnetization relaxation dynamics in the absence of an external magnetic field, while 3 shows field-induced frequency-dependent χ M ′′ signals. An ideal octahedral geometry around the lanthanide ion is predicted to be unsuitable for the design of a single-molecule magnet (SMM); nevertheless, complex 2 exhibits slow relaxation of magnetization with a record high anisotropy barrier for a six-coordinate Dy(III) complex. A rationale for this unusual behavior is detailed and reveals the strength of the synthetic methodology developed.
IP International Journal of Orthopaedic Rheumatology
0.5-1% of World Population is affected by Rheumatoid Arthritis (RA). The Prevalence of the diseas... more 0.5-1% of World Population is affected by Rheumatoid Arthritis (RA). The Prevalence of the disease in Indians is about 0.7%. Hand is the earliest and most common presentation in Rheumatoid Arthritis. Though there has been a lot of advancement in the medical management of RA patients with the advent of newer and safer drugs, hand surgery still plays an important role in the treatment of the patients. As with the medical field, there has been development in the surgical modalities too in the management of deformities and in the improvement of functional outcomes of Hand Surgery in RA patients. This review assesses the efficacy of operative management in Rheumatoid Hand.
2018 International Conference on Innovation in Engineering and Technology (ICIET), 2018
A novel optic sensor using platinum-loaded tungsten oxide (Pt/WO 3) and a silicon microring reson... more A novel optic sensor using platinum-loaded tungsten oxide (Pt/WO 3) and a silicon microring resonator for detection of hydrogen gas at room temperature was developed and tested. The sensing principle is mainly based on the resonant wavelength shift caused by the catalytic combustion reaction of hydrogen. In a previous study, it was found that Pt/WO 3 film could not be deposited uniformly on the surface of the microring. To solve this problem, acetylene glycol surfactant was used and mixed with Pt/WO 3 precursor solution. Electron probe microanalyzer images of the device surface showed that the Pt/WO 3 layer successfully covered the target part of the microring. When this device was tested, a 580-pm resonant wavelength shift was observed after 20-min exposure to pure hydrogen gas at room temperature. When the previous device was tested under the same condition, a 160-pm resonant wavelength shift was observed, so the sensitivity (defined by the wavelength shift after 20-min exposure to sample gas) of the developed device was approximately four times larger than that of the previous one.
Design and Implementation of Programmable Logic Controller Based Automatic Transfer Switch
Journal of Artificial Intelligence, Machine Learning and Neural Network, 2022
A PLC-based automatic transfer switch (ATS) may improve production in the industry efficiency and... more A PLC-based automatic transfer switch (ATS) may improve production in the industry efficiency and also the household power connection. It's an electrical switch that may be used to change the load when the main power is failing to supply electricity. Manually controlled transfer switches exist. In this scenario, a switch must be thrown by an operator to take manual control of the system. Some, on the other hand, are activated automatically when the main power source fails. When a major source of electricity is no longer functioning, power from a new or used generator can be either manually or automatically transferred when utilize a transfer switch for transferring control to the on- side application. Using a programmable logic controller (PLC), we describe the implementation and design of an automatic transfer switch (ATS). The primary function of a transfer switch is to divert electricity from the main grid to a standby power supply. Single-phase and three-phase circuit breake...
Design and Analysis of A High Frequency Bow-tie Printed Ridge Gap Waveguide Antenna
Journal of Image Processing and Intelligent Remote Sensing, 2022
Millimeter and microwave wave components are in high demand, which will have a substantial influe... more Millimeter and microwave wave components are in high demand, which will have a substantial influence on the development of 5G networks. In this work, Ridge Gap Waveguide is used to develop a planar high-gain antenna. The main objective of this study is to develop a wideband, high-gain antenna capable of supporting the expected need for high data transmission in the future. For this reason, a thorough examination of PRGW has been presented, along with a series of high-gain antenna designs that have been extensively tested. In the future, this antenna array might be used for 5G connectivity, and it meets all mm-wave band specifications. We have designed a novel tri slotted PRGW antenna which size is small (3.256x3.256x0.03 mm3), but the gain, bandwidth, directivity and rad efficiency is high with respect to other larger PRGW antenna. Although the volume of the proposed antenna is small, also it provides better Gain, Directivity and VSWR with respect to the larger conventional PRGW ant...
Design and Analysis of Multiband Antipodal Vivaldi Array Antenna (AVAA) for E-Band Communications
2019 4th International Conference on Electrical Information and Communication Technology (EICT), 2019
In this research paper a novel Antipodal Vivaldi Antenna (AVA) which can be used in E-band commun... more In this research paper a novel Antipodal Vivaldi Antenna (AVA) which can be used in E-band communication because the proposed antenna provides higher gain at frequency range 80–100 GHz with overall dimension 20times2020\times 2020times20 mm2. The antenna is designed using a dielectric substrate Roger RT 5880 and simulated using computer simulation technology (CST). The single element AVA has four resonance frequencies at 83.15 GHz, 87.67 GHz, 91.23 GHz and 95.77GHz. The maximum gain of the single AVA is 8.4 dB at 95.77 GHz while the 2times12\times 12times1 and 4times14\times 14times1 array antennas provide maximum gain of 10.4 dB and 11.5 dB respectively. The maximum radiation efficiency of the three proposed antennas at all resonance frequencies is around 90%. So the proposed antennas are convenient for high capacity point-to-point communications and can also be used for automobile radars, WiGig, mobile backhauls, and for high speed wireless 5G communication.
CCDC 2027176: Experimental Crystal Structure Determination
Medical Science, 2022
Aim: The aim of this study is to see how well radiography students understand radiation protectio... more Aim: The aim of this study is to see how well radiography students understand radiation protection equipment, how to use it, and how to handle it. Methods: A prospective questionnaire-based research was done by the Department of Radiology and Imaging. A validated questionnaire was provided to undergraduate radiography students to complete the study. Result: In this study, 267 Radiology and imaging undergraduate and diploma students completed a questionnaire. To put their knowledge of radiation protective equipment, its use, and handling to the test, they participated in theoretical sessions and hospital placements. In the group, there were 82 (30.7%) girls and 185 (69.2%) males. Conclusion: According to the findings, radiology departments should provide appropriate theoretical classes for the transfer of knowledge on radiation protection systems, their use, and management. This questionnaire-based study discovered that current radiation protective equipment, its use, and handling skills among radiography students at Assam Down Town University's faculty of paramedical sciences were inadequate, and that this could be improved with well-designed training and theoretical sessions. As a result, we strongly advise all members of the medical community to attend seminars, guest lectures, training sessions, and other related events.
Magnetization relaxation dynamics of a rare coordinatively unsaturated Co(ii) complex: experimental and theoretical insights
Chemical Communications, 2020
A three-coordinate Co(ii) complex with the molecular formula [Li(DME)3][Co(L)3] (1) was isolated.... more A three-coordinate Co(ii) complex with the molecular formula [Li(DME)3][Co(L)3] (1) was isolated. The influence of the geometry on the SH parameters, and in turn on the magnetization relaxation, is investigated by SQUID and EPR measurements.
Chiral tetranuclear copper(ii) complexes: synthesis, optical and magnetic properties
New Journal of Chemistry, 2020
The chiral tetranuclear Cu(ii) cubane complexes with the general molecular formula [Cu4(R-L1)4] (... more The chiral tetranuclear Cu(ii) cubane complexes with the general molecular formula [Cu4(R-L1)4] (R-1) and [Cu4(S-L1)4] (S-1) exhibit ferromagnetic exchange coupling, which is in contrast to the literature reports. This is corroborated by theoretical calculations.
Chemical Communications, 2019
We synthesized the crystalline and glassy state of a coordination polymer displaying proton condu... more We synthesized the crystalline and glassy state of a coordination polymer displaying proton conduction and guest-accessible porosity.
Inorganic Chemistry, 2019
Inorganic Chemistry, 2018
Two lanthanide-containing structurally analogous porous coordination polymers (PCPs) have been is... more Two lanthanide-containing structurally analogous porous coordination polymers (PCPs) have been isolated with the general molecular formula [Ln 2 (L 1) 2 (H 2 O) 4 (ox)] n .4nH 2 O (where L 1 = fumarate, ox = oxalate; Ln = Dy (1), Gd (2)). Thermogravimetric analysis (TGA) and TG-MS measurements performed on 1 and 2 suggest that not only the solvated water molecules in the crystal lattice but also the four coordinated water molecules on the respective lanthanides in 1 and 2 are removed upon activation. Due to the removal of the waters, 1 and 2 lost their crystallinity and became amorphous, as confirmed by powder X-ray diffraction (PXRD). We propose the molecular formula [Ln 2 (L 1) 2 (ox)] n for the amorphous phase of 1 and 2 (where Ln = Dy (1′), Gd (2′)) on the basis of XANES, EXAFS, and other experimental investigations. Magnetization relaxation dynamics probed on 1 and 1′ reveal two different relaxation processes with effective energy barriers of 53.5 and 7.0 cm −1 for 1 and 45.1 and 6.4 cm −1 for 1′, which have been rationalized by detailed ab initio calculations. For the isotropic lanthanide complexes 2 and 2′, magnetocaloric effect (MCE) efficiency was estimated through detailed magnetization measurements. We have estimated −ΔS m values of 52.48 and 41.62 J kg 1− K −1 for 2′ and 2, respectively, which are one of the largest values reported for an extended structure. In addition, a 26% increase in −ΔS m value in 2′ in comparison to 2 is achieved by simply removing the passively contributing (for MCE) solvated water molecule in the lattice and coordinated water molecules.
TAJ: Journal of Teachers Association, 2018
This was a hospital based study done to see the prevalence of metabolic syndrome in acute myocard... more This was a hospital based study done to see the prevalence of metabolic syndrome in acute myocardial infarction patients in Bangladesh. A total of 325 acute myocardial infarction patients attending in coronary care unit Rajshahi medical college hospital were included in this study. According to modified NCEP ATP III criteria 48.5% of subjects aged ≥ 20 years had the metabolic syndrome and it was more commonly seen in women than in men (72% vs 37.4%). The metabolic syndrome is associated with an increased risk of acute myocardial syndrome. Key ward : metabolic syndrome, acute myocardial syndrome, NCEP ATP III criteria.
Inorganic Chemistry, 2018
Three structurally analogous hexanuclear ruthenium(III) complexes were isolated with the general ... more Three structurally analogous hexanuclear ruthenium(III) complexes were isolated with the general molecular formula of [Ru 6 III (O) 2 (μ 4-η 2-η 2-CH 2 O 2)(t-BuCO 2) 12 (L) 2 ] where L = pyridine (1) or 4-dimethylamino pyridine (DMAP; 2) or 4-cyanopyridine (3). Complexes 1 and 3 were solved in the tetragonal I4̅ c2 and P4 1 2 1 2 space group, respectively, while 2 crystallized in the monoclinic system with P2 1 /c space group. In all three complexes, two oxo-centered Ru(III) triangles were bridged by a unique and a rare methylenediolate (CH 2 O 2) 2−) ligand. This (CH 2 O 2) 2− group is reported to be an intermediate, which is not isolated in its metal-free form, to date, as it is unstable. Control experiments performed evidently reveal that the unique reaction condition followed is mandatory to isolate 1−3 and the origin of (CH 2 O 2) 2− is unknown at the moment, as no precursor was used to form this intermediate. The presence of (CH 2 O 2) 2− identified through X-ray diffraction was further unambiguously confirmed by various 1D (1 H and 13 C) and 2D-NMR (HSQC, TOCSY, NOESY, and DEPT) spectroscopies. Direct current (dc) magnetic susceptibility measurements performed on 1 and 2 reveal the predominant antiferromagnetic exchange interaction between the Ru(III) centers result in a diamagnetic ground state at 2.0 K. The paramagnetic influence of 1−3 at room temperature evidently felt by the 1 H nuclei of the (CH 2 O 2) 2− unit predominates compared to other NMR active nuclei in the complexes. The presence of an electron donating or withdrawing substituent on the terminal pyridine results in significant change in the dihedral angle of two oxo-centered triangular (Ru 3 O−) planes. The change in the structural parameters of 1−3 due to the substituents markedly reflected on the absorption profile and redox behavior, which are systematically investigated. Preliminary galvanostatic charge/discharge cycling experiments performed on a representative complex (3) suggest that 3 can be a promising candidate to employ as an effective multiple electron charge carrier in a nonaqueous redox flow battery.
Dalton transactions (Cambridge, England : 2003), Jan 30, 2018
A series of three isostructural tetranuclear complexes with the general molecular formula [Ln4(μ3... more A series of three isostructural tetranuclear complexes with the general molecular formula [Ln4(μ3-OH)4(L)4(μ2-piv)4(MeOH)4] (Ln = Gd 1, Dy 2 and Ho 3; LH = [1,3-bis(o-methoxyphenyl)-propane-1,3-dione]) were isolated and unambiguously characterized by single crystal XRD. Under similar reaction conditions, simply changing the co-ligand from pivalate to 2,6-bis(hydroxymethyl)-p-cresol (LH'3) led to the isolation of dinuclear Ln(iii) complexes with the general molecular formula [Ln2(L)4(μ2-LH'2)2]·4DMF (Ln = Gd 4, Dy 5 and Ho 6). Direct current magnetic susceptibility data studies on the polycrystalline sample of 1-6 and the results reveal the existence of weak antiferromagnetic exchange interactions between the lanthanide ions in 1 which is evident from the spin Hamiltonian (SH) parameters (J1 = -0.055 cm-1 and g = 2.01) extracted by fitting χMT(T). On the other hand, though complex 4 exhibits weak antiferromagnetic coupling (J1 = -0.048 cm-1 and g = 1.99) between the Gd(iii) i...
Inorganic chemistry, Jan 31, 2017
A series of monomeric lanthanide Schiff base complexes with the molecular formulas [Ce(HL)3(NO3)3... more A series of monomeric lanthanide Schiff base complexes with the molecular formulas [Ce(HL)3(NO3)3] (1) and [Ln(HL)2(NO3)3], where Ln(III) = Tb (2), Ho (3), Er (4), and Lu (5), were isolated and characterized by single-crystal X-ray diffraction (XRD). Single-crystal XRD reveals that, except for 1, all complexes possess two crystallographically distinct molecules within the unit cell. Both of these crystallographically distinct molecules possess the same molecular formula, but the orientation of the coordinating ligand distinctly differs from those in complexes 2-5. Alternating-current magnetic susceptibility measurement reveals that complexes 1-3 exhibit slow relaxation of magnetization in the presence of an optimum external magnetic field. In contrast to 1-3, complex 4 shows a blockade of magnetization in the absence of an external magnetic field, a signature characteristic of a single-ion magnet (SIM). The distinct magnetic behavior observed in 4 compared to other complexes is corr...
Chemistry (Weinheim an der Bergstrasse, Germany), Jan 6, 2017
Four complexes containing Dy(III) and Pr(III) ions and their Ln(III) -Zn(II) analogs have been sy... more Four complexes containing Dy(III) and Pr(III) ions and their Ln(III) -Zn(II) analogs have been synthesized in order to study the influence that a diamagnetic Zn(II) ion has on the electronic structure and hence, the magnetic properties of the Dy(III) and Pr(III) single ions. Single-crystal X-ray diffraction revealed the molecular structures as [Dy(III) (HL)2 (NO3 )3 ] (1), [Pr(III) (HL)2 (NO3 )3 ] (2), [Zn(II) Dy(III) (L)2 (CH3 CO2 )(NO3 )2 ] (3) and [Zn(II)2 Pr(III) (L)2 (CH3 CO2 )4 (NO3 )] (4) (where HL=2-methoxy-6-[(E)-phenyliminomethyl]phenol). The dc and ac magnetic data were collected for all four complexes. Compounds 1 and 3 display frequency dependent out-of-phase susceptibility signals (χM "), which is a characteristic signature for a single-molecule magnet (SMM). Although 1 and 3 are chemically similar, a fivefold increase in the anisotropic barrier (Ueff ) is observed experimentally for 3 (83 cm(-1) ), compared to 1 (16 cm(-1) ). To rationalize the larger anisotropic...
Dalton transactions (Cambridge, England : 2003), Jan 10, 2017
The reaction of anhydrous MCl3 (M = Al(iii) or Ga(iii)) with one-electron-reduced 3,5-di-tert-but... more The reaction of anhydrous MCl3 (M = Al(iii) or Ga(iii)) with one-electron-reduced 3,5-di-tert-butyl-1,2-ortho-benzoquinone (using metallic sodium) led us to isolate two distinct metal complexes of Al(iii) and Ga(iii), which were structurally and magnetically characterized. Complex 1 crystallized in the monoclinic P21/n space group, whereas 2 crystallized in the triclinic P1[combining macron] space group. Interestingly, whereas the Al(iii) derivative was obtained as a dimer with the molecular formula [Al2(μ-HL(-))2(L˙(-))4] (1) (where L˙(-) is a semiquinonate radical and HL(-) is a monoanionic catecholate ligand), the Ga(iii) derivative crystallized as [Ga(L˙(-))3] (2), which is a polymorph of a previously reported complex. The presence of both catecholate and/or semiquinonate ligands in 1 and 2 was confirmed by single-crystal X-ray diffraction, mass spectrometry, and NMR and infrared spectroscopy techniques. The crystalline phase purity of the complexes was confirmed by powder X-ray...
IP International Journal of Orthopaedic Rheumatology
A group of inflammatory arthritic disorders known as juvenile idiopathic arthritis (JIA) are char... more A group of inflammatory arthritic disorders known as juvenile idiopathic arthritis (JIA) are characterized by arthritis of uncertain origin that first manifests in a child under the age of 16. This is the most common chronic rheumatological disease of childhood. The JIA is present in every country and has an incidence of 1 in 100,000. Despite the absence of a documented etiology, there are a number of genetic and environmental risk factors as well as immunologic abnormalities that can be seen and used to infer information about the pathophysiology of the illness. Although there is no cure, modern therapy can frequently reduce the underlying inflammation and enhance function and symptoms. In this case patient showed complete resolution of symptoms with no signs of recurrence. As a result, it helps patient to live a healthy life.
Inorganic Chemistry, 2018
Controlling quantum tunneling of magnetization (QTM) is a persistent challenge in lanthanide-base... more Controlling quantum tunneling of magnetization (QTM) is a persistent challenge in lanthanide-based single-molecule magnets. As the exchange interaction is one of the key factors in controlling the QTM, we targeted lanthanide complexes with an increased number of radicals around the lanthanide ion. On the basis of our targeted approach, a family of pseudo-octahedral lanthanide/transition-metal complexes were isolated with the general molecular formula of [M(L •−) 3 ] (M = Gd (1), Dy (2), Er (3), Y (4)) using the redox-active iminopyridyl (L •−) ligand exclusively, which possess the highest ratio of radicals to lanthanide reported for discrete metal complexes. Direct current magnetic susceptibility studies suggest that dominant antiferromagnetic interactions exist between the radical and lanthanide ions in all of the complexes, which is strongly corroborated by magnetic data fitting using a Heisenberg−Dirac−Van Vleck (HDVV) Hamiltonian (−2J Hamiltonian). A good agreement between the fit and the experimental magnetic data obtained using g = 2, J rad-rad = −111.9 cm −1 for 4 and g = 1.99, J rad-rad = −111.9 cm −1 , J Gd-rad = −1.85 cm −1 for 1. Complex 2 shows frequency-dependent slow magnetization relaxation dynamics in the absence of an external magnetic field, while 3 shows field-induced frequency-dependent χ M ′′ signals. An ideal octahedral geometry around the lanthanide ion is predicted to be unsuitable for the design of a single-molecule magnet (SMM); nevertheless, complex 2 exhibits slow relaxation of magnetization with a record high anisotropy barrier for a six-coordinate Dy(III) complex. A rationale for this unusual behavior is detailed and reveals the strength of the synthetic methodology developed.
IP International Journal of Orthopaedic Rheumatology
0.5-1% of World Population is affected by Rheumatoid Arthritis (RA). The Prevalence of the diseas... more 0.5-1% of World Population is affected by Rheumatoid Arthritis (RA). The Prevalence of the disease in Indians is about 0.7%. Hand is the earliest and most common presentation in Rheumatoid Arthritis. Though there has been a lot of advancement in the medical management of RA patients with the advent of newer and safer drugs, hand surgery still plays an important role in the treatment of the patients. As with the medical field, there has been development in the surgical modalities too in the management of deformities and in the improvement of functional outcomes of Hand Surgery in RA patients. This review assesses the efficacy of operative management in Rheumatoid Hand.
2018 International Conference on Innovation in Engineering and Technology (ICIET), 2018
A novel optic sensor using platinum-loaded tungsten oxide (Pt/WO 3) and a silicon microring reson... more A novel optic sensor using platinum-loaded tungsten oxide (Pt/WO 3) and a silicon microring resonator for detection of hydrogen gas at room temperature was developed and tested. The sensing principle is mainly based on the resonant wavelength shift caused by the catalytic combustion reaction of hydrogen. In a previous study, it was found that Pt/WO 3 film could not be deposited uniformly on the surface of the microring. To solve this problem, acetylene glycol surfactant was used and mixed with Pt/WO 3 precursor solution. Electron probe microanalyzer images of the device surface showed that the Pt/WO 3 layer successfully covered the target part of the microring. When this device was tested, a 580-pm resonant wavelength shift was observed after 20-min exposure to pure hydrogen gas at room temperature. When the previous device was tested under the same condition, a 160-pm resonant wavelength shift was observed, so the sensitivity (defined by the wavelength shift after 20-min exposure to sample gas) of the developed device was approximately four times larger than that of the previous one.
Design and Implementation of Programmable Logic Controller Based Automatic Transfer Switch
Journal of Artificial Intelligence, Machine Learning and Neural Network, 2022
A PLC-based automatic transfer switch (ATS) may improve production in the industry efficiency and... more A PLC-based automatic transfer switch (ATS) may improve production in the industry efficiency and also the household power connection. It's an electrical switch that may be used to change the load when the main power is failing to supply electricity. Manually controlled transfer switches exist. In this scenario, a switch must be thrown by an operator to take manual control of the system. Some, on the other hand, are activated automatically when the main power source fails. When a major source of electricity is no longer functioning, power from a new or used generator can be either manually or automatically transferred when utilize a transfer switch for transferring control to the on- side application. Using a programmable logic controller (PLC), we describe the implementation and design of an automatic transfer switch (ATS). The primary function of a transfer switch is to divert electricity from the main grid to a standby power supply. Single-phase and three-phase circuit breake...
Design and Analysis of A High Frequency Bow-tie Printed Ridge Gap Waveguide Antenna
Journal of Image Processing and Intelligent Remote Sensing, 2022
Millimeter and microwave wave components are in high demand, which will have a substantial influe... more Millimeter and microwave wave components are in high demand, which will have a substantial influence on the development of 5G networks. In this work, Ridge Gap Waveguide is used to develop a planar high-gain antenna. The main objective of this study is to develop a wideband, high-gain antenna capable of supporting the expected need for high data transmission in the future. For this reason, a thorough examination of PRGW has been presented, along with a series of high-gain antenna designs that have been extensively tested. In the future, this antenna array might be used for 5G connectivity, and it meets all mm-wave band specifications. We have designed a novel tri slotted PRGW antenna which size is small (3.256x3.256x0.03 mm3), but the gain, bandwidth, directivity and rad efficiency is high with respect to other larger PRGW antenna. Although the volume of the proposed antenna is small, also it provides better Gain, Directivity and VSWR with respect to the larger conventional PRGW ant...
Design and Analysis of Multiband Antipodal Vivaldi Array Antenna (AVAA) for E-Band Communications
2019 4th International Conference on Electrical Information and Communication Technology (EICT), 2019
In this research paper a novel Antipodal Vivaldi Antenna (AVA) which can be used in E-band commun... more In this research paper a novel Antipodal Vivaldi Antenna (AVA) which can be used in E-band communication because the proposed antenna provides higher gain at frequency range 80–100 GHz with overall dimension 20times2020\times 2020times20 mm2. The antenna is designed using a dielectric substrate Roger RT 5880 and simulated using computer simulation technology (CST). The single element AVA has four resonance frequencies at 83.15 GHz, 87.67 GHz, 91.23 GHz and 95.77GHz. The maximum gain of the single AVA is 8.4 dB at 95.77 GHz while the 2times12\times 12times1 and 4times14\times 14times1 array antennas provide maximum gain of 10.4 dB and 11.5 dB respectively. The maximum radiation efficiency of the three proposed antennas at all resonance frequencies is around 90%. So the proposed antennas are convenient for high capacity point-to-point communications and can also be used for automobile radars, WiGig, mobile backhauls, and for high speed wireless 5G communication.
CCDC 2027176: Experimental Crystal Structure Determination
Medical Science, 2022
Aim: The aim of this study is to see how well radiography students understand radiation protectio... more Aim: The aim of this study is to see how well radiography students understand radiation protection equipment, how to use it, and how to handle it. Methods: A prospective questionnaire-based research was done by the Department of Radiology and Imaging. A validated questionnaire was provided to undergraduate radiography students to complete the study. Result: In this study, 267 Radiology and imaging undergraduate and diploma students completed a questionnaire. To put their knowledge of radiation protective equipment, its use, and handling to the test, they participated in theoretical sessions and hospital placements. In the group, there were 82 (30.7%) girls and 185 (69.2%) males. Conclusion: According to the findings, radiology departments should provide appropriate theoretical classes for the transfer of knowledge on radiation protection systems, their use, and management. This questionnaire-based study discovered that current radiation protective equipment, its use, and handling skills among radiography students at Assam Down Town University's faculty of paramedical sciences were inadequate, and that this could be improved with well-designed training and theoretical sessions. As a result, we strongly advise all members of the medical community to attend seminars, guest lectures, training sessions, and other related events.
Magnetization relaxation dynamics of a rare coordinatively unsaturated Co(ii) complex: experimental and theoretical insights
Chemical Communications, 2020
A three-coordinate Co(ii) complex with the molecular formula [Li(DME)3][Co(L)3] (1) was isolated.... more A three-coordinate Co(ii) complex with the molecular formula [Li(DME)3][Co(L)3] (1) was isolated. The influence of the geometry on the SH parameters, and in turn on the magnetization relaxation, is investigated by SQUID and EPR measurements.
Chiral tetranuclear copper(ii) complexes: synthesis, optical and magnetic properties
New Journal of Chemistry, 2020
The chiral tetranuclear Cu(ii) cubane complexes with the general molecular formula [Cu4(R-L1)4] (... more The chiral tetranuclear Cu(ii) cubane complexes with the general molecular formula [Cu4(R-L1)4] (R-1) and [Cu4(S-L1)4] (S-1) exhibit ferromagnetic exchange coupling, which is in contrast to the literature reports. This is corroborated by theoretical calculations.
Chemical Communications, 2019
We synthesized the crystalline and glassy state of a coordination polymer displaying proton condu... more We synthesized the crystalline and glassy state of a coordination polymer displaying proton conduction and guest-accessible porosity.
Inorganic Chemistry, 2019
Inorganic Chemistry, 2018
Two lanthanide-containing structurally analogous porous coordination polymers (PCPs) have been is... more Two lanthanide-containing structurally analogous porous coordination polymers (PCPs) have been isolated with the general molecular formula [Ln 2 (L 1) 2 (H 2 O) 4 (ox)] n .4nH 2 O (where L 1 = fumarate, ox = oxalate; Ln = Dy (1), Gd (2)). Thermogravimetric analysis (TGA) and TG-MS measurements performed on 1 and 2 suggest that not only the solvated water molecules in the crystal lattice but also the four coordinated water molecules on the respective lanthanides in 1 and 2 are removed upon activation. Due to the removal of the waters, 1 and 2 lost their crystallinity and became amorphous, as confirmed by powder X-ray diffraction (PXRD). We propose the molecular formula [Ln 2 (L 1) 2 (ox)] n for the amorphous phase of 1 and 2 (where Ln = Dy (1′), Gd (2′)) on the basis of XANES, EXAFS, and other experimental investigations. Magnetization relaxation dynamics probed on 1 and 1′ reveal two different relaxation processes with effective energy barriers of 53.5 and 7.0 cm −1 for 1 and 45.1 and 6.4 cm −1 for 1′, which have been rationalized by detailed ab initio calculations. For the isotropic lanthanide complexes 2 and 2′, magnetocaloric effect (MCE) efficiency was estimated through detailed magnetization measurements. We have estimated −ΔS m values of 52.48 and 41.62 J kg 1− K −1 for 2′ and 2, respectively, which are one of the largest values reported for an extended structure. In addition, a 26% increase in −ΔS m value in 2′ in comparison to 2 is achieved by simply removing the passively contributing (for MCE) solvated water molecule in the lattice and coordinated water molecules.
TAJ: Journal of Teachers Association, 2018
This was a hospital based study done to see the prevalence of metabolic syndrome in acute myocard... more This was a hospital based study done to see the prevalence of metabolic syndrome in acute myocardial infarction patients in Bangladesh. A total of 325 acute myocardial infarction patients attending in coronary care unit Rajshahi medical college hospital were included in this study. According to modified NCEP ATP III criteria 48.5% of subjects aged ≥ 20 years had the metabolic syndrome and it was more commonly seen in women than in men (72% vs 37.4%). The metabolic syndrome is associated with an increased risk of acute myocardial syndrome. Key ward : metabolic syndrome, acute myocardial syndrome, NCEP ATP III criteria.
Inorganic Chemistry, 2018
Three structurally analogous hexanuclear ruthenium(III) complexes were isolated with the general ... more Three structurally analogous hexanuclear ruthenium(III) complexes were isolated with the general molecular formula of [Ru 6 III (O) 2 (μ 4-η 2-η 2-CH 2 O 2)(t-BuCO 2) 12 (L) 2 ] where L = pyridine (1) or 4-dimethylamino pyridine (DMAP; 2) or 4-cyanopyridine (3). Complexes 1 and 3 were solved in the tetragonal I4̅ c2 and P4 1 2 1 2 space group, respectively, while 2 crystallized in the monoclinic system with P2 1 /c space group. In all three complexes, two oxo-centered Ru(III) triangles were bridged by a unique and a rare methylenediolate (CH 2 O 2) 2−) ligand. This (CH 2 O 2) 2− group is reported to be an intermediate, which is not isolated in its metal-free form, to date, as it is unstable. Control experiments performed evidently reveal that the unique reaction condition followed is mandatory to isolate 1−3 and the origin of (CH 2 O 2) 2− is unknown at the moment, as no precursor was used to form this intermediate. The presence of (CH 2 O 2) 2− identified through X-ray diffraction was further unambiguously confirmed by various 1D (1 H and 13 C) and 2D-NMR (HSQC, TOCSY, NOESY, and DEPT) spectroscopies. Direct current (dc) magnetic susceptibility measurements performed on 1 and 2 reveal the predominant antiferromagnetic exchange interaction between the Ru(III) centers result in a diamagnetic ground state at 2.0 K. The paramagnetic influence of 1−3 at room temperature evidently felt by the 1 H nuclei of the (CH 2 O 2) 2− unit predominates compared to other NMR active nuclei in the complexes. The presence of an electron donating or withdrawing substituent on the terminal pyridine results in significant change in the dihedral angle of two oxo-centered triangular (Ru 3 O−) planes. The change in the structural parameters of 1−3 due to the substituents markedly reflected on the absorption profile and redox behavior, which are systematically investigated. Preliminary galvanostatic charge/discharge cycling experiments performed on a representative complex (3) suggest that 3 can be a promising candidate to employ as an effective multiple electron charge carrier in a nonaqueous redox flow battery.
Dalton transactions (Cambridge, England : 2003), Jan 30, 2018
A series of three isostructural tetranuclear complexes with the general molecular formula [Ln4(μ3... more A series of three isostructural tetranuclear complexes with the general molecular formula [Ln4(μ3-OH)4(L)4(μ2-piv)4(MeOH)4] (Ln = Gd 1, Dy 2 and Ho 3; LH = [1,3-bis(o-methoxyphenyl)-propane-1,3-dione]) were isolated and unambiguously characterized by single crystal XRD. Under similar reaction conditions, simply changing the co-ligand from pivalate to 2,6-bis(hydroxymethyl)-p-cresol (LH'3) led to the isolation of dinuclear Ln(iii) complexes with the general molecular formula [Ln2(L)4(μ2-LH'2)2]·4DMF (Ln = Gd 4, Dy 5 and Ho 6). Direct current magnetic susceptibility data studies on the polycrystalline sample of 1-6 and the results reveal the existence of weak antiferromagnetic exchange interactions between the lanthanide ions in 1 which is evident from the spin Hamiltonian (SH) parameters (J1 = -0.055 cm-1 and g = 2.01) extracted by fitting χMT(T). On the other hand, though complex 4 exhibits weak antiferromagnetic coupling (J1 = -0.048 cm-1 and g = 1.99) between the Gd(iii) i...
Inorganic chemistry, Jan 31, 2017
A series of monomeric lanthanide Schiff base complexes with the molecular formulas [Ce(HL)3(NO3)3... more A series of monomeric lanthanide Schiff base complexes with the molecular formulas [Ce(HL)3(NO3)3] (1) and [Ln(HL)2(NO3)3], where Ln(III) = Tb (2), Ho (3), Er (4), and Lu (5), were isolated and characterized by single-crystal X-ray diffraction (XRD). Single-crystal XRD reveals that, except for 1, all complexes possess two crystallographically distinct molecules within the unit cell. Both of these crystallographically distinct molecules possess the same molecular formula, but the orientation of the coordinating ligand distinctly differs from those in complexes 2-5. Alternating-current magnetic susceptibility measurement reveals that complexes 1-3 exhibit slow relaxation of magnetization in the presence of an optimum external magnetic field. In contrast to 1-3, complex 4 shows a blockade of magnetization in the absence of an external magnetic field, a signature characteristic of a single-ion magnet (SIM). The distinct magnetic behavior observed in 4 compared to other complexes is corr...
Chemistry (Weinheim an der Bergstrasse, Germany), Jan 6, 2017
Four complexes containing Dy(III) and Pr(III) ions and their Ln(III) -Zn(II) analogs have been sy... more Four complexes containing Dy(III) and Pr(III) ions and their Ln(III) -Zn(II) analogs have been synthesized in order to study the influence that a diamagnetic Zn(II) ion has on the electronic structure and hence, the magnetic properties of the Dy(III) and Pr(III) single ions. Single-crystal X-ray diffraction revealed the molecular structures as [Dy(III) (HL)2 (NO3 )3 ] (1), [Pr(III) (HL)2 (NO3 )3 ] (2), [Zn(II) Dy(III) (L)2 (CH3 CO2 )(NO3 )2 ] (3) and [Zn(II)2 Pr(III) (L)2 (CH3 CO2 )4 (NO3 )] (4) (where HL=2-methoxy-6-[(E)-phenyliminomethyl]phenol). The dc and ac magnetic data were collected for all four complexes. Compounds 1 and 3 display frequency dependent out-of-phase susceptibility signals (χM "), which is a characteristic signature for a single-molecule magnet (SMM). Although 1 and 3 are chemically similar, a fivefold increase in the anisotropic barrier (Ueff ) is observed experimentally for 3 (83 cm(-1) ), compared to 1 (16 cm(-1) ). To rationalize the larger anisotropic...
Dalton transactions (Cambridge, England : 2003), Jan 10, 2017
The reaction of anhydrous MCl3 (M = Al(iii) or Ga(iii)) with one-electron-reduced 3,5-di-tert-but... more The reaction of anhydrous MCl3 (M = Al(iii) or Ga(iii)) with one-electron-reduced 3,5-di-tert-butyl-1,2-ortho-benzoquinone (using metallic sodium) led us to isolate two distinct metal complexes of Al(iii) and Ga(iii), which were structurally and magnetically characterized. Complex 1 crystallized in the monoclinic P21/n space group, whereas 2 crystallized in the triclinic P1[combining macron] space group. Interestingly, whereas the Al(iii) derivative was obtained as a dimer with the molecular formula [Al2(μ-HL(-))2(L˙(-))4] (1) (where L˙(-) is a semiquinonate radical and HL(-) is a monoanionic catecholate ligand), the Ga(iii) derivative crystallized as [Ga(L˙(-))3] (2), which is a polymorph of a previously reported complex. The presence of both catecholate and/or semiquinonate ligands in 1 and 2 was confirmed by single-crystal X-ray diffraction, mass spectrometry, and NMR and infrared spectroscopy techniques. The crystalline phase purity of the complexes was confirmed by powder X-ray...