Multidirectional-charge-transfer urchin-type Mo-doped W₁₈O₄₉ nanostructures on CdS nanorods for enhanced photocatalytic hydrogen evolution

Bhavani, P.,Praveen Kumar, D.,Jeong, Seonghyun,Kim, Eun Hwa,Park, Hanbit,Hong, Sangyeob,Gopannagari, Madhusudana,Amaranatha Reddy, D.,Song, Jae Kyu,Kim, Tae Kyu The Royal Society of Chemistry 2018 Catalysis Science & Technology Vol.8 No.7

<P>Transition metal oxides (TMOs) have attracted attention because they provide eco-friendly ways of collecting solar energy and are more stable than sulfides or phosphides for photoirradiation over long periods without photocorrosion. Among TMOs, tungsten oxides have attracted considerable attention owing to their excellent electron transport properties and good resilience to photocorrosion in aqueous media. However, pristine WO3 exhibits low photocatalytic activity because of the rapid recombination of its photogenerated charge-carriers and its narrow photo-absorption range. Consequently, the monoclinic oxygen-deficient (WO3−δ) material W18O49 (≅WO2.73) has attracted greater interest than typical tungsten oxides due to its high chemical stability and large number of oxygen vacancies (OVs). In particular, the water splitting efficiency of W18O49 is enhanced by doping with Mo, which modifies the intrinsic chemical properties of W18O49 without disturbing the crystal structure while producing more active sites. Furthermore, by tuning the morphology of Mo-W18O49 (MWO), the photocatalytic activity of MWO-embedded CdS was greatly enhanced by the very large surface area and supplementary active sites. To that end, we developed an urchin-type MWO cocatalyst integrated into CdS nanorods (NRs) by simple methods. The catalyst exhibits an enhanced production rate of H2 (40.225 mmol h<SUP>−1</SUP> g<SUP>−1</SUP>) under simulated solar light irradiation, which is 20 times higher than that of pristine CdS NRs. The urchin-type morphology significantly shortens charge-carrier transport distances. The oxygen deficiency and Mo dopant in the W18O49 system also improve the number of active sites, which promotes the efficient utilization of light, excellent electron-transport properties, and good resilience to photocorrosion. These properties are especially beneficial for the effective excitation and separation of charge-carriers that are directed to the reduction of protons to H2. Moreover, to the best of our knowledge, this material exhibits the best performance among reported tungsten-based oxides as a cocatalyst on CdS composites.</P>

A Novel 21 Level Switched Capacitor Modular Multilevel Inverter Using Gray Wolf Optimization

Bhavani M.,Manoharan P. S. 대한전기학회 2022 Journal of Electrical Engineering & Technology Vol.17 No.1

This paper introduces the design and development of a modular switched multilevel inverter with a reduced number of components. Conventional multilevel inverters (MLIs), owing to its achievement and widespread uses in industries, there have been many advancements and improvement of novel topologies. This study generalizes the basic unit of a switched capacitor topology using a cascaded H-bridge structure to realize a switched capacitor multilevel inverter (SCMLI). This paper proposes a single phase 21-level inverter topology with fl oating capacitor unit meeting aforementioned requirements. The major objective of this study is to propose a topology to attain higher levels with a reduced number of switches. Further, three optimization techniques namely Ant Lion Optimization (ALO), Equilibrium Optimizer (EO) and Gray Wolf Optimization (GWO) to control the inverter switching angle are studied and compared. The optimum switching angles of the SC-MLI to generate the required fundamental voltage is identifi ed using GWO. The performance of the proposed inverter is investigated in terms of output voltage, Total harmonic distortion (THD), switching and conduction losses. The stress on switching components due to switching and conduction losses is analysed. In MATLAB/Simulink, the simulations are performed and control strategy is implemented in digital platform using a Field Programmable Gate Array (FPGA) based processor. The simulation results are validated using the experimental results

Influence of Metal Particle Size on Oxidative CO₂Reforming of Methane over Supported Nickel Catalysts: Effects of Second-Metal Addition

Bhavani, Annabathini Geetha,Kim, Won Young,Lee, Jin Woo,Lee, Jae Sung Wiley (John WileySons) 2015 ChemCatChem Vol.7 No.9

Synthesis and Physical Characterization of -Fe2O3 and (+ )-Fe2O3 Nanoparticles

P. Bhavani,N. Ramamanohar Reddy,I. Venkata Subba Reddy 한국물리학회 2017 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.70 No.2

Magnetic nanoparticles were synthesized at different hydrothermal temperatures (HT; 100, 130, 160 and 190 C) by using a facile hydrothermal route combined with a subsequent calcination process. The calcined materials were analyzed for phase, microstructure, and magnetic and dielectric properties through different characterization techniques. The structural analyses revealed that the material prepared at a HT of 100 C and sequentially calcined at 300 C for 3 h showed a high degree of the maghemite structure. On the other hand calcined materials showed a small additional peak belonging to the hematite structure. FESEM micrographs of the materials calcined at HT, of 100 C and 190 C showed spherical-like nanoparticles with diameters in range 30 - 54 nm. Materials prepared at a HT of 160 C followed by calcination at 300 C for 3 h exhibited the highest saturation magnetization, Ms = 67 emu/g, with a lower coercivity; all materials were in a single domain state. A high dielectric constant (105.54) was observed for the calcined material that had been prepared at a HT of 130 C. The dielectric properties of synthesized materials showed an almost frequency- independent behavior.

Secure Data Transmission through RDH

S. Bhavani,B. Raviteja 보안공학연구지원센터(IJSIP) 2014 International Journal of Signal Processing, Image Vol.7 No.6

Nowadays, with the rapid growth in information technology more and more images and data are available on the internet. So there is a need to provide some kind of authentication to such important data. When the sender transmits the image to the receiver, there may be intruders present in between who may capture the image. After capturing the image the mage the intruder may view the meaningful content in the image. This may not be the problem in some cases. But if we consider security applications like medical and military images then such distortion is unacceptable. To avoid misuse or loss of information several reversible data hiding techniques (RDH) are implemented. This paper gives details on watermarking, LSB, Histogram and RDH using optimum Thresholding with related results.

α-Gal Nanoparticles in CNS Trauma: I. In Vitro Activation of Microglia Towards a Pro-Healing State

Gopalakrishnan Bhavani,Galili Uri,Dunbar August,Solorio Luis,Shi Riyi,Li Jianming 한국조직공학과 재생의학회 2024 조직공학과 재생의학 Vol.21 No.3

Background: Macrophages and microglia play critical roles after spinal cord injury (SCI), with the pro-healing, anti-inflammatory (M2) subtype being implicated in tissue repair. We hypothesize that promoting this phenotype within the post-injured cord microenvironment may provide beneficial effects for mitigating tissue damage. As a proof of concept, we propose the use of nanoparticles incorporating the carbohydrate antigen, galactose-α-1,3-galactose (α-gal epitope) as an immunomodulator to transition human microglia (HMC3) cells toward a pro-healing state. Methods: Quiescent HMC3 cells were acutely exposed to α-gal nanoparticles in the presence of human serum and subsequently characterized for changes in cell shape, expression of anti or pro-inflammatory markers, and secretion of phenotype-specific cytokines. Results: HMC3 cells treated with serum activated α-gal nanoparticles exhibited rapid enlargement and shape change in addition to expressing CD68. Moreover, these activated cells showed increased expression of anti-inflammatory markers like Arginase-1 and CD206 without increasing production of pro-inflammatory cytokines TNF-α or IL-6. Conclusion: This study is the first to show that resting human microglia exposed to a complex of α-gal nanoparticles and anti-Gal (from human serum) can be activated and polarized toward a putative M2 state. The data suggests that α-gal nanoparticles may have therapeutic relevance to the CNS microenvironment, in both recruiting and polarizing macrophages/microglia at the application site. The immunomodulatory activity of these α-gal nanoparticles post-SCI is further described in the companion work (Part II). Background: Macrophages and microglia play critical roles after spinal cord injury (SCI), with the pro-healing, anti-inflammatory (M2) subtype being implicated in tissue repair. We hypothesize that promoting this phenotype within the post-injured cord microenvironment may provide beneficial effects for mitigating tissue damage. As a proof of concept, we propose the use of nanoparticles incorporating the carbohydrate antigen, galactose-α-1,3-galactose (α-gal epitope) as an immunomodulator to transition human microglia (HMC3) cells toward a pro-healing state. Methods: Quiescent HMC3 cells were acutely exposed to α-gal nanoparticles in the presence of human serum and subsequently characterized for changes in cell shape, expression of anti or pro-inflammatory markers, and secretion of phenotype-specific cytokines. Results: HMC3 cells treated with serum activated α-gal nanoparticles exhibited rapid enlargement and shape change in addition to expressing CD68. Moreover, these activated cells showed increased expression of anti-inflammatory markers like Arginase-1 and CD206 without increasing production of pro-inflammatory cytokines TNF-α or IL-6. Conclusion: This study is the first to show that resting human microglia exposed to a complex of α-gal nanoparticles and anti-Gal (from human serum) can be activated and polarized toward a putative M2 state. The data suggests that α-gal nanoparticles may have therapeutic relevance to the CNS microenvironment, in both recruiting and polarizing macrophages/microglia at the application site. The immunomodulatory activity of these α-gal nanoparticles post-SCI is further described in the companion work (Part II).

α-Gal Nanoparticles in CNS Trauma: II. Immunomodulation Following Spinal Cord Injury (SCI) Improves Functional Outcomes

Gopalakrishnan Bhavani,Galili Uri,Saenger Megan,Burket Noah J.,Koss Wendy,Lokender Manjari S.,Wolfe Kaitlyn M.,Husak Samantha J.,Stark Collin J.,Solorio Luis,Cox Abigail,Dunbar August,Shi Riyi,Li Jian 한국조직공학과 재생의학회 2024 조직공학과 재생의학 Vol.21 No.3

BACKGROUND: Previous investigations have shown that local application of nanoparticles presenting the carbohydrate moiety galactose-α-1,3-galactose (α-gal epitopes) enhance wound healing by activating the complement system and recruiting pro-healing macrophages to the injury site. Our companion in vitro paper suggest α-gal epitopes can similarly recruit and polarize human microglia toward a pro-healing phenotype. In this continuation study, we investigate the in vivo implications of α-gal nanoparticle administration directly to the injured spinal cord. METHODS: α-Gal knock-out (KO) mice subjected to spinal cord crush were injected either with saline (control) or with α-gal nanoparticles immediately following injury. Animals were assessed longitudinally with neurobehavioral and histological endpoints. RESULTS: Mice injected with α-gal nanoparticles showed increased recruitment of anti-inflammatory macrophages to the injection site in conjunction with increased production of anti-inflammatory markers and a reduction in apoptosis. Further, the treated group showed increased axonal infiltration into the lesion, a reduction in reactive astrocyte populations and increased angiogenesis. These results translated into improved sensorimotor metrics versus the control group. CONCLUSIONS: Application of α-gal nanoparticles after spinal cord injury (SCI) induces a pro-healing inflammatory response resulting in neuroprotection, improved axonal ingrowth into the lesion and enhanced sensorimotor recovery. The data shows α-gal nanoparticles may be a promising avenue for further study in CNS trauma. BACKGROUND: Previous investigations have shown that local application of nanoparticles presenting the carbohydrate moiety galactose-α-1,3-galactose (α-gal epitopes) enhance wound healing by activating the complement system and recruiting pro-healing macrophages to the injury site. Our companion in vitro paper suggest α-gal epitopes can similarly recruit and polarize human microglia toward a pro-healing phenotype. In this continuation study, we investigate the in vivo implications of α-gal nanoparticle administration directly to the injured spinal cord. METHODS: α-Gal knock-out (KO) mice subjected to spinal cord crush were injected either with saline (control) or with α-gal nanoparticles immediately following injury. Animals were assessed longitudinally with neurobehavioral and histological endpoints. RESULTS: Mice injected with α-gal nanoparticles showed increased recruitment of anti-inflammatory macrophages to the injection site in conjunction with increased production of anti-inflammatory markers and a reduction in apoptosis. Further, the treated group showed increased axonal infiltration into the lesion, a reduction in reactive astrocyte populations and increased angiogenesis. These results translated into improved sensorimotor metrics versus the control group. CONCLUSIONS: Application of α-gal nanoparticles after spinal cord injury (SCI) induces a pro-healing inflammatory response resulting in neuroprotection, improved axonal ingrowth into the lesion and enhanced sensorimotor recovery. The data shows α-gal nanoparticles may be a promising avenue for further study in CNS trauma.

Oxidative Stress and Antioxidant Defenses in Asthmatic Murine Model Exposed to Printer Emissions and Environmental Tobacco Smoke

Konga, Durga Bhavani,Kim, Yoonshin,Hong, Seung Cheol,Roh, Young Man,Lee, Cheol Min,Kim, Ki Youn,Lee, So Min Begell House Inc. 2009 Journal of environmental pathology, toxicology, an Vol.28 No.4

<P>Exposure to particulate emissions from printer and cigarette smoke affects the structure and function of mitochondria, which may account for the pathogenesis of respiratory diseases. The addition of charge for the pollutant aerosols may increase the toxicity by their deposition in the lower respiratory tract. The mitochondrial damage in the lung of asthmatic mice was assessed by examining the levels of reactive oxygen species (ROS), lipid peroxides, reduced glutathione, and the activities of isocitrate dehydrogenase, alpha-ketoglutarate dehydrogenase, succinate dehydrogenase, malate dehydrogenase, complexes I to IV, and cytochrome c. The oxidative phosphorylation (levels of adenosine triphosphatase) was evaluated for the assessment of mitochondrial functional capacity. We found highly significant elevated levels of ROS, lipid peroxides, and decreased levels of mitochondrial enzymes in the mice exposed to environmental tobacco smoke and printer emissions + environmental tobacco smoke (ETS). However, mice exposed to printer emissions alone exhibited slight significant variations in the parameters studied. From the results, we conclude that printer emissions exert a synergistic effect in the presence of ETS and induce intense damage to the lung mitochondria by disrupting the structural and functional integrity of the mitochondrial membrane.</P>

Measurement of IT-Enabled Production Capability and Benchmarking of Public Hospitals : Data Envelopment Analysis

Sri Vidhya Bhavani Munuswamy,Prakash Sai Lokachari 한국경영정보학회 2023 Asia Pacific Journal of Information Systems Vol.33 No.1

Blocking of Zeolite Pore by Loading Ni-Pt Nanoparticles for Maximization of Isomerization Selectivity

( A. Geetha Bhavani ),( N. Subba Reddy ) 한국화학공학회 2020 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.58 No.4

Zeolite HY is wet impregnated with Ni (0.1, 0.3, 0.4, 0.5 wt%), Pt (0.1 wt%) and reduced in presence of hydrogen to form nanosized particles of Ni and Pt. All the catalysts were characterized by XRD, TEM, ESCA, NH₃-TPD, Pyridine adsorbed FT-IR and BET. Characterization results confirm that the Ni and Pt fractions effectively rehabilitated the physio-chemical properties of the zeolite HY catalysts. Further, all the reduced catalyst were screened with hydroisomerization of m-xylene at LHSV = 2.0 h-1 in the temperature range 250-400 ºC in steps of 50 ºC in hydrogen atmosphere (20 ml/g). The addition of Ni to Pt catalyst increases hydroisomerization conversion, as well as maximizes p-xylene selectivity by restricting the pore size. The increasing trend in activity continues up to 0.3 wt% of Ni and 0.1 wt% Pt addition over zeolite HY. The increasing addition of Ni increases the total number of active metallic sites to exposed, which increases the metallic sites/acid sites ratio towards the optimum value for these reactions by better balance of synergic effect for stable activity. The rate of deactivation is pronounced on monometallic catalysts. The results confirm the threshold Ni addition is highly suitable for hydroisomerization reaction for product selectivity over Ni-Pt bimetallic/support catalysts.