Cryogenic microwave dielectric properties of Mg₂TiO₄ ceramics added with CeO₂ nanoparticles

Bhuyan, Ranjan K.,Thatikonda, Santhosh K.,Dobbidi, Pamu,Renehan, J.M.,Jacob, Mohan V. Techno-Press 2014 Advances in materials research Vol.3 No.2

The microwave dielectric properties of $CeO_2$ nanoparticles (0.5, 1.0 & 1.5wt%) doped $Mg_2TiO_4$ (MTO) ceramics have been investigated at cryogenic temperatures. The XRD patterns of the samples were refined using the full proof program reveal the inverse spinel structure without any secondary phases. The addition of $CeO_2$ nanoparticles lowered the sintering temperature with enhancement in density and grain size as compared to pure MTO ceramics. This is attributed to the higher sintering velocity of the fine particles. Further, the microwave dielectric properties of the MTO ceramics were measured at cryogenic temperatures in the temperature range of 6.5-295 K. It is observed that the loss tangent ($tan{\delta}$) of all the samples increased with temperature. However, the $CeO_2$ nanoparticles doped MTO ceramics manifested lower loss tangents as compared to the pure MTO ceramics. The loss tangents of the pure and MTO ceramics doped with 1.5 wt% of $CeO_2$ nanoparticles measured at 6.5K are found to be $6.6{\times}10^{-5}$ and $5.4{\times}10^{-5}$, respectively. The addition of $CeO_2$ nanoparticles did not cause any changes on the temperature stability of the MTO ceramics at cryogenic temperatures. On the other hand, the temperature coefficient of the permittivity increased with rise in temperature and with the wt% of $CeO_2$ nanoparticles. The obtained lower loss tangent values at cryogenic temperatures can be attributed to the decrease in both intrinsic and extrinsic losses in the MTO ceramics.

Production of a Thermostable Nitrilase in a Lab Scale Stirred Tank Bioreactor

V. K. Nigam,A. K. Khandelwal,A. Agarwal,M. K. Mohan,A. S. Vidyarthi 보안공학연구지원센터 2012 International Journal of Bio-Science and Bio-Techn Vol.4 No.3

Optimization of Heat Transfer Parameter in Fractal Tree Microchannel with Al2O3 Nano-Fluids Using Taguchi and GRA Method

E. Manikandan,K. Velmurugan,G.G. Sozhamannan,Balamuruga Mohan Raj.G,V.S.K. Venkatachalapathy 한양대학교 청정에너지연구소 2023 Journal of Ceramic Processing Research Vol.24 No.6

Grey relational analysis of the multiple responses, including Reynolds number, Nusselt number, heat transfer (W), heattransfer coefficient (W/m2 K), and heat flux (W/m2), was done as part of experiments based on a Taguchi orthogonal array. The best parameter levels was calculated and selected based on GRA on basis of the Grey Relational Grade (GRG). AnANOVA has been used to identify factors that significantly contribute to the response based on grade. Experiments was conductedat the optimum predicted conditions (Al2O3) and the response was found as follows; Reynolds Number (592), NusseltNumber (2.5), Heat transfer (Q) (510), Flux (W/m2) (17.8) and Heat transfer Coefficient (W/m2 K) (394). The experimentalvalue was found to be correlated with the predicted values of Reynolds number (610), Nusselt number (2.6), heat transfer (Q)(530), heat transfer coefficient (W/m2 K) (415), and heat flux (W/m2) (18.5), respectively. The experimental data were foundto have an excellent knowledge under the recommended conditions. Our study is a preliminary step towards developing asubstantially effective Al2O3-based base fluid to enhance the performance of the heat transfer process in a copper-based serpentineshape heat exchanger

Investigations on electrical properties of (PVA:NaF) polymer electrolytes for electrochemical cell applications

P. Balaji Bhargav,V. Madhu Mohan,A.K. Sharma,V.V.R.N. Rao 한국물리학회 2009 Current Applied Physics Vol.9 No.1

Solid polymer electrolytes based on poly (vinyl alcohol) (PVA) complexed with sodium fluoride (NaF) at different weight percent ratios were prepared using solution cast technique. The structural properties of these electrolyte films were examined by XRD studies. The XRD data revealed that the amorphous domains of PVA polymer matrix increased with increase of NaF salt concentration. The complexation of the salt with the polymer was confirmed by FT-IR studies. Electrical conductivity was measured in the temperature range of 303–373 K and the conductivity was found to increase with the increase of dopant concentration as well as temperature. The dielectric constant (ε') increased with the increase in temperature and decreased with the increase in frequency. A loss peak was identified at 365 K in the dielectric loss spectra and is attributed to the orientation of polar groups. Measurement of transference number was carried out to investigate the nature of charge transport in these polymer electrolyte films using Wagner’s polarization technique and Watanabe technique. Transport number data showed that the charge transport in these polymer electrolyte systems was predominantly due to ions and in particular due to anions. Using these polymer electrolytes, solid state electrochemical cells were fabricated. Various cell parameters like open circuit voltage (OCV), short circuit current (SCC), power density and energy density were determined. Solid polymer electrolytes based on poly (vinyl alcohol) (PVA) complexed with sodium fluoride (NaF) at different weight percent ratios were prepared using solution cast technique. The structural properties of these electrolyte films were examined by XRD studies. The XRD data revealed that the amorphous domains of PVA polymer matrix increased with increase of NaF salt concentration. The complexation of the salt with the polymer was confirmed by FT-IR studies. Electrical conductivity was measured in the temperature range of 303–373 K and the conductivity was found to increase with the increase of dopant concentration as well as temperature. The dielectric constant (ε') increased with the increase in temperature and decreased with the increase in frequency. A loss peak was identified at 365 K in the dielectric loss spectra and is attributed to the orientation of polar groups. Measurement of transference number was carried out to investigate the nature of charge transport in these polymer electrolyte films using Wagner’s polarization technique and Watanabe technique. Transport number data showed that the charge transport in these polymer electrolyte systems was predominantly due to ions and in particular due to anions. Using these polymer electrolytes, solid state electrochemical cells were fabricated. Various cell parameters like open circuit voltage (OCV), short circuit current (SCC), power density and energy density were determined.

Antifertility Effect of Neem (Azadrichta indica) Seed Kernel Meal in Chickens

Mohan, J.,Tyagi, Praveen K.,Tyagi, Pramod K.,Verma, S.V.S.,Moudgal, R.P. Asian Australasian Association of Animal Productio 1997 Animal Bioscience Vol.10 No.6

The reproductive performance of forty two male broilers divided into three similar groups and fed on isocaloric and isonitrogneous diets containing 0, 10 or 20% water washed neem seed kernel meal (WWNSKM) was investigated from 20 to 32-wks of age. Results on semen characteristics revealed that feeding of WWNSKM led to significant (p < 0.05) reduction in semen volume, sperm concentration associated with increased incidences of morphological abnormalities in the spermatozoa when compared to that of the control birds. A drastic reduction in the fertilizing ability of spermatozoa was observed, the adverse effects being more at higher inclusion level of the cake. Hatchability of eggs also declined in the WWNSKM fed group. Histological examination of testes revealed a higher number of degenerating cells and poor spermatogenesis along with multinucleated giant cells in the seminiferous tubules of the testes of birds receiving the high dose of WWNSKM in diet. It may be concluded that the feeding of WWNSKM by incorporating in isocaloric and isonitrogneous diets to cockerels is associated with adverse effect on their fertility.

Laccase Production Using Pleurotus ostreatus 1804 Immobilized on PUFCubes in Batch and Packed Bed Reactors: Influence of Culture Conditions

K. Krishna Prasad,S. Venkata Mohan,Y. Vijaya Bhaskar,S. V. Ramanaiah,V. Lalit Babu,B. R. Pati,P. N. Sarma 한국미생물학회 2005 The journal of microbiology Vol.43 No.3

The feasibility of laccase production by immobilization of Pleurotus ostreatus 1804 on polyurethane foam (PUF) cubes with respect to media composition was studied in both batch and reactor systems. Enhanced laccase yield was evidenced due to immobilization. A relatively high maximum laccase activity of 312.6 U was observed with immobilized mycelia in shake flasks compared to the maximum laccase activity of free mycelia (272.2 U). It is evident from this study that the culture conditions studied, i.e. biomass level, pH, substrate concentration, yeast extract concentration, Cu2+ concentration, and alcohol nature, showed significant influence on the laccase yield. Gel electrophoretic analysis showed the molecular weight of the laccase produced by immobilized P. ostreatus to be 66 kDa. The laccase yield was significantly higher and more rapid in the packed bed reactor than in the shake flask experiments. A maximum laccase yield of 392.9 U was observed within 144 h of the fermentation period with complete glucose depletion.

Mineral magnetic properties of ultisol profiles from tropical southern India

Mohan Reethu,Kizhur Sandeep,Joju G. Sebastian,Anish K. Warrier,Geetha H. Aravind,Abdul K. Rafaz,Jithin Jose,Radhakrishnan Akshay,Vadakkath V. Suhaiba 한국지질과학협의회 2023 Geosciences Journal Vol.27 No.5

The magnetic grain size, mineralogy and concentration of five ultisol sequences (lateritic soil profiles) developed on different parent rocks (syenite, dolerite, charnockite, gneiss and sandstone) in southwestern India were investigated to gain a better understanding of the pedogenic processes under tropical climate. Field investigations reveal the presence of various horizons in the lateritic profiles, such as saprolite, saprock, pallid zone, mottled zone, pebble horizon and top soil. These horizons exhibit differences in their mineral magnetic, Fourier Transform Infrared Spectroscopic (FTIR), Diffuse Reflectance Spectroscopic (redness %, amplitudes of goethite (AGt) and haematite (AHm)) and particle size properties. Magnetic susceptibility (χlf) values of the ultisol profiles varies from 5.8 to 2858.7 × 10−8m3kg−1, whereas percentage frequency dependent susceptibility (χfd %) ranges between 0.15% and 14.0%. The FTIR spectra reveal the presence of minerals like haematite, goethite, kaolinite and quartz. The upper horizons (top-soil and pebble horizon) are marked by magnetic enhancement by ultra-fine grained superparamagnetic (SP) minerals with low coercivity, most likely magnetite/maghemite. Whereas, the lower horizons (saprock, saprolite, pallid zone horizons) exhibit no magnetic enhancement and are characterized by antiferromagnetic minerals, e.g., haematite/goethite. The unweathered parent rock is characterized by low coercivity minerals of coarser magnetic grain size with a little to no superparamagnetic (SP) grains. However, the magnitude of enhancement of fine grained ferrimagnetic grains in the top soil in relation to bottom horizons varies among the five lateritic profiles. The degree of enhancement and production of the fine-grained superparamagnetic grains in topsoil decreases in the order charnockite > syenite > sandstone > gneiss > dolerite. Because the doleritic parent rock exhibits a high initial Fe concentration, it is difficult to ascertain the degree of pedogenesis, due to a strong lithogenic signature, which decreases towards the profile top. The tropical soils in the region have undergone a higher degree of pedogenesis with increased magnetic mineral concentration compared to temperate soils. However, magnetic grain size appears to be the same in both soil types. The magnetic enhancement in the topsoil may be due to the neoformation of fine-grained SP magnetite, aided by sufficient Fe supply, alternate wetting and drying cycles, dehydration, oxidation and redox conditions.

Spatial data integration for disaster/emergency management: an Indian experience

V. Bhanumurthy,K. Ram Mohan Rao,G. Jai Sankar,P. V. Nagamani 대한공간정보학회 2017 Spatial Information Research Vol.25 No.2

Disaster/emergency management needs rapid sharing of essential database for effective decision making. It requires comprehensive and structured database elements for handling emergency situations. The essential database includes variety of multi-scale information covering core, disaster specific and non-spatial information for effective decision making. Every disaster is unique and requires specific information for effective handling of the situation in all the phases of emergency management. Spatial technologies enable effective disaster risk management to assess and map extent of natural events such as floods, cyclones, tsunami, landslide, earthquake, forest fire etc. These disaster products derived from space based inputs generated in near/real time are extremely useful for planning and decision making. However, building spatial database system is a complex task because of key challenges. In this article the concept of spatial data integration is defined for effective integration procedures, storage methods, analysis, and dissemination of these inputs as web services for decision support tools for effective disaster/ emergency management.

A hybrid method for fundamental heart sound segmentation using group-sparsity denoising and variational mode decomposition

V. G. Sujadevi,Neethu Mohan,S. Sachin Kumar,S. Akshay,K. P. Soman 대한의용생체공학회 2019 Biomedical Engineering Letters (BMEL) Vol.9 No.4

Segmentation of fundamental heart sounds–S1 and S2 is important for automated monitoring of cardiac activity includingdiagnosis of the heart diseases. This pa-per proposes a novel hybrid method for S1 and S2 heart sound segmentation usinggroup sparsity denoising and variation mode decomposition (VMD) technique. In the proposed method, the measured phonocardiogram(PCG) signals are denoised using group sparsity algorithm by exploiting the group sparse (GS) property ofPCG signals. The denoised GS-PCG signals are then decomposed into subsequent modes with specifi c spectral characteristicsusing VMD algorithm. The appropriate mode for further processing is selected based on mode central frequencies and modeenergy. It is then followed by the extraction of Hilbert envelope (HEnv) and a thresholding on the selected mode to segmentS1 and S2 heart sounds. The performance advantage of the proposed method is verifi ed using PCG signals from benchmarkdatabases namely eGeneralMedical, Littmann, Washington, and Michigan. The proposed hybrid algorithm has achieved asensitivity of 100%, positive predictivity of 98%, accuracy of 98% and detection error rate of 1.5%. The promising resultsobtained suggest that proposed approach can be considered for automated heart sound segmentation.

Laccase Production Using Pleurotus ostreatus 1804 Immobilized on PUF Cubes in Batch and Packed Bed Reactors: Influence of Culture Conditions

Prasad K. Krishna,Mohan S. Venkata,Bhaskar Y. Vijaya,Ramanaiah S. V.,Babu V. Lalit,Pati B. R.,Sarma P. N. The Microbiological Society of Korea 2005 The journal of microbiology Vol.43 No.3

The feasibility of laccase production by immobilization of Pleurotus ostreatus 1804 on polyurethane foam (PUF) cubes with respect to media composition was studied in both batch and reactor systems. Enhanced laccase yield was evidenced due to immobilization. A relatively high maximum laccase activity of 312.6 U was observed with immobilized mycelia in shake flasks compared to the maximum laccase activity of free mycelia (272.2 U). It is evident from this study that the culture conditions studied, i.e. biomass level, pH, substrate concentration, yeast extract concentration, $Cu^{2+}$ concentration, and alcohol nature, showed significant influence on the laccase yield. Gel electrophoretic analysis showed the molecular weight of the laccase produced by immobilized P. ostreatus to be 66 kDa. The laccase yield was significantly higher and more rapid in the packed bed reactor than in the shake flask experiments. A maximum laccase yield of 392.9 U was observed within 144 h of the fermentation period with complete glucose depletion.