Effect of Ba and Ho co-doping on crystal structure, phase transformation, magnetic properties and dielectric properties of BiFeO3

Jogender Singh, Ashish Agarwal,Ashish Agarwal,Sujata Sanghi,Tanvi Bhasin,Manisha Yadav,Umesh Bhakar,Ompal Singh 한국물리학회 2019 Current Applied Physics Vol.19 No.3

Multiferroics having composition Bi0.80-xBa0.20HoxFeO3 (BBFO, BBHFO5, BBHFO10, BBHFO15 and BBHFO20 for x=0.0, 0.05, 0.10, 0.15 and 0.20 respectively) were synthesized by method of solid state reaction. The crystal structure has been studied using X-ray diffraction technique. The X-ray patterns show enormous transform in crystal structure at concentration x=0.20. The Rietveld refinement of XRD patterns indicates that at concentration x=0.0 sample have rhombohedral structure with R3c space group while for the concentration x=0.05, 0.10, 0.15 and 0.20, the mixed phase including rhombohedral R3c and triclinic P1 space groups were obtained with best fitting. This phase transformation in crystal structure is observed due to mismatching of ionic radii of doped ions and parent ions. Magnetic properties of all samples were carried out by using vibrating sample magnetometry. M-H hysteresis loops shows that with doping of Ba and Ho antiferromagnetic BiFeO3 (BFO) transforms into ferromagnetic. The dielectric and ferroelectric measurements were carried out which shows that dielectric constant, dielectric loss and ferroelectric properties are enhanced with co-doping of Ho in comparison of the pristine BFO due to structure deformation and decrease in oxygen vacancies with higher concentration of Ho. Significant improvement has been observed in dielectric constant and remnant magnetization values with increasing content of Ho and decrease in the dielectric loss.

Expression profiling of mitogen-activated protein kinase genes from chickpea (Cicer arietinum L.) in response to Helicoverpa armigera, wounding and signaling compounds

Indrakant Kumar Singh,Sumit Kumar,Sujata Singh,Archana Singh 한국응용곤충학회 2017 Journal of Asia-Pacific Entomology Vol.20 No.3

The Mitogen-activated Protein Kinase (MAPK) Cascades play a crucial role in the regulation of defense responses in plants. Herbivory- or wounding-related MAPKs, SA-induced protein kinase (SIPK) and wound-induced protein kinase (WIPK) have been identified to be associated with insect attack. However, function of MAPKs in crop plants in response to herbivory largely remains unknown. Here, we evaluated the expression patterns of fifteen MAPK genes from chickpea in response to infestation by a major pest, Helicoverpa armigera via quantitative realtime PCR (qPCR). Subsequently, we compared the expression patterns of CaMAPKs in response to two related but different processes i.e. insect attack and mechanical wounding. Signaling compounds such as Jasmonates, Salicylic acid and Ethylene also play crucial function in defense response. Therefore, we have also examined the expression profiles of H. armigera-inducible MAPK genes in response to these signaling compounds. Our results revealed that out of fifteen CaMAPKs, seven of the CaMAPKs are upregulated in response to H. armigera and two are downregulated. Additionally, they show differential expression on comparing Helicoverpa-infestation and wounding. Jasmonates and Ethylene mainly regulate CaMAPK genes that may play a role in defense against Helicoverpa-infestation. This study provides insights into the participation of MAPKs in defense against insects.

Interference and noise analysis for hybrid FSO/RF-based 6G mobile backhaul

Soyinka Nath(Soyinka Nath ),Shree Prakash Singh(Shree Prakash Singh ),Sujata Sengar(Sujata Sengar ) 한국전자통신연구원 2022 ETRI Journal Vol.44 No.6

Optical wireless communication, or free space optics, is a promising solution for backhauls in sixth-generation mobile systems. However, the susceptibility of optical links to weather conditions has led to FSO links being furnished with radio frequency (RF) backups. These Hybrid FSO/RF systems provide enhanced link availability but lead to RF resource wastage. Cognitive radio technology, in contrast, is well known for its optimal use of RF resources and may be combined with an FSO link to create a Cognitive Hybrid FSO/RF system. This work uses such a system to analyze a configuration for a mobile backhaul in sixth-generation mobile systems. This configuration can seamlessly coexist with established large scale RF cellular networks. The performance of this configuration is analyzed with respect to outage probability and average bit error by considering the impact of optical channel turbulence, misalignment loss, RF interference, and noise. Mathematical closed-form expressions are verified by simulations.

Dielectric relaxation, conductivity behavior and magnetic properties of Mg substituted Zn―Li ferrites

Navneet Singh,Ashish Agarwal,Sujata Sanghi 한국물리학회 2011 Current Applied Physics Vol.11 No.3

Spinel ferrites having compositions Zn_0.5Li_(1-2x)Mg_xFe_2O_4 (0 ≤ x ≤ 0.5) have been prepared by sol-gel auto combustion technique. The dielectric properties of these ferrites have been studied using impedance measurements in the frequency range 10 Hz―10 MHz and in the temperature range 310―473 K. The effect of temperature, frequency and composition on dielectric constant (ε´), dielectric loss (tanδ) and conductivity (σ) have been discussed in terms of hopping of charge carriers (Fe^2+↔Fe^3+). The occurrence of peak in the dielectric loss (tanδ) spectra is found to be temperature and composition dependent. The electrical modulus formulism has also been employed to study the relaxation dynamics of charge carriers and the results indicate the presence of non-Debye type of relaxation in these ferrites. Identical values of activation energy for dc conduction (E_dc) and for conductivity relaxation (E_M˝) reveal that the charge carriers have to overcome the same energy barrier while conducting and relaxing. A single ‘master curve’for normalized plots of all the modulus isotherms observed for a given composition indicates the temperature independence of dynamical process for charge carriers in the present ferrites. The absence of hysteresis and non-attainment of saturation magnetization (even at 8 kOe) suggests the super paramagnetic behaviour of these ferrites.

Moringa oleifera Leaf Extract Prevents Isoproterenol-Induced Myocardial Damage in Rats: Evidence for an Antioxidant, Antiperoxidative, and Cardioprotective Intervention

Nandave, Mukesh,Ojha, Shreesh Kumar,Joshi, Sujata,Kumari, Santosh,Arya, Dharamvir Singh The Korean Society of Food Science and Nutrition 2009 Journal of medicinal food Vol.12 No.1

The present study evaluated cardioprotective effect of lyophilized hydroalcoholic extract of Moringa oleifera in the isoproterenol (ISP)-induced model of myocardial infarction. Wistar albino male rats were divided into three groups and orally fed saline once daily alone (sham) or with ISP (ISP control) or ISP with M. oleifera (200 mg/kg), respectively, for 1 month. On days 29 and 30 of administration, rats of the ISP control and M. oleifera-ISP groups were administered ISP (85 mg/kg, s.c.) at an interval of 24 hours. On day 31, hemodynamic parameters (mean arterial pressure [MAP], heart rate [HR], left ventricular end-diastolic pressure [LVEDP], and left ventricular peak positive [(+) LV dP/dt] and negative [(-) LV dP/dt] pressures were recorded. At the end of the experiment, the animals were sacrificed, and hearts were excised and processed for biochemical, histopathological, and ultrastructural studies. Chronic treatment with M. oleifera demonstrated mitigating effects on ISP-induced hemodynamic [HR, (+) LV dP/dt, (-) LV dP/dt, and LVEDP] perturbations. Chronic M. oleifera treatmen resulted in significant favorable modulation of the biochemical enzymes (superoxide dismutase, catalase, glutathione peroxidase, lactate dehydrogenase, and creatine kinase-MB) but failed to demonstrate any significant effect on reduced glutathione compared to the ISP control group. Moringa treatment significantly prevented the rise in lipid peroxidation in myocardial tissue. Furthermore, M. oleifera also prevented the deleterious histopathological and ultrastructural perturbations caused by ISP. Based on the results of the present study, it can be concluded that M. oleifera extract possesses significant cardioprotective effect, which may be attributed to its antioxidant, antiperoxidative, and myocardial preservative properties.

Moringa oleifera Leaf Extract Prevents Isoproterenol-Induced Myocardial Damage in Rats: Evidence for an Antioxidant, Antiperoxidative, and Cardioprotective Intervention

Mukesh Nandave,Shreesh Kumar Ojha,Sujata Joshi,Santosh Kumari,Dharamvir Singh Arya 한국식품영양과학회 2009 Journal of medicinal food Vol.12 No.1

The present study evaluated cardioprotective effect of lyophilized hydroalcoholic extract of Moringa oleifera in the isoproterenol (ISP)-induced model of myocardial infarction. Wistar albino male rats were divided into three groups and orally fed saline once daily alone (sham) or with ISP (ISP control) or ISP with M. oleifera (200 mg/kg), respectively, for 1 month. On days 29 and 30 of administration, rats of the ISP control and M. oleifera-ISP groups were administered ISP (85 mg/kg, s.c.) at an interval of 24 hours. On day 31, hemodynamic parameters (mean arterial pressure [MAP], heart rate [HR], left ventricular end-diastolic pressure [LVEDP], and left ventricular peak positive [(+) LV dP/dt] and negative [(–) LV dP/dt] pressures were recorded. At the end of the experiment, the animals were sacrificed, and hearts were excised and processed for biochemical, histopathological, and ultrastructural studies. Chronic treatment with M. oleifera demonstrated mitigating effects on ISP-induced hemodynamic [HR, (+) LV dP/dt, (–) LV dP/dt, and LVEDP] perturbations. Chronic M. oleifera treatment resulted in significant favorable modulation of the biochemical enzymes (superoxide dismutase, catalase, glutathione peroxidase, lactate dehydrogenase, and creatine kinase-MB) but failed to demonstrate any significant effect on reduced glutathione compared to the ISP control group. Moringa treatment significantly prevented the rise in lipid peroxidation in myocardial tissue. Furthermore, M. oleifera also prevented the deleterious histopathological and ultrastructural perturbations caused by ISP. Based on the results of the present study, it can be concluded that M. oleifera extract possesses significant cardioprotective effect, which may be attributed to its antioxidant, antiperoxidative, and myocardial preservative properties.