An Ultrahigh Vacuum Complementary Metal Oxide Silicon Compatible nonlithographic System to Fabricate nanoparticle-based Devices

Nanoparticles of metals and semiconductors are promising for the implementation of a variety of photonic and electronic devices with superior performances and new functionalities. However, their successful implementation has been limited due to the lack of appropriate fabrication processes that are suitable for volume manufacturing. The current techniques for the fabrication of nanoparticles either are solution based, thus requiring complex surface passivation, or have severe constraints over the choice of particle size and material. We have developed an ultrahigh vacuum system for the implementation of a complex nanosystem that is flexible and compatible with the silicon integrated circuit process, thus making it suitable for volume manufacturing. The system also allows the fabrication of Ohmic contacts and isolation dielectrics in an integrated manner, which is a requirement for most electronic and photonic devices. We have demonstrated the power and the flexibility of this new system for the manufacturing of nanoscale devices by implementing a variety of structures incorporating nanoparticles. Descriptions of this new fabrication system together with experimental results are presented in this article. The system explains the method of size-selected deposition of nanoparticles of any metallic, semiconducting, and (or) insulating materials on any substrate, which is very important in fabricating useful nanoparticle-baseddevices. It has also been shown that at elevated substrate temperature, a selective deposition of the nanoparticles is observed near the grain-boundary regions. However, in these natural systems, there will always be low and favorable energy states present away from the grain-boundary regions, leading to the undesirable deposition of nanoparticles in the far-grain-boundary regions, too

STRUCTURE OF COBALT CATALYSTS DURING FISCHER TROPSCH SYNTHESIS: ROLE OF ADSORBATES AND MECHANISTIC CONSEQUENCES

Ph.DDOCTOR OF PHILOSOPH

Synergistic effects of bimetallic Mo-W carbide in hydrodeoxygenation of guaiacol

Bimetallic MO-W carbide was synthesized via temperature-programmed reduction to generate a β-Mo2C like phase with bulk morphology in order to investigate the synergistic effects of a combination of molybdenum and tungsten in carbide. The solid was characterized using X-ray diffraction (XRD), N2 physisorption, X-ray photoelectron spectroscopy (XPS), H2-chemisorption, and ammonia temperature programmed desorption (TPD-NH3). The bimetallic carbide exhibited a significantly higher density of H2-activating sites than the corresponding monometallic carbides prepared using the same method. In the HDO of guaiacol at 350oC, MoWC yielded the highest hydrodeoxygenation (HDO) catalytic activity and produced completely deoxygenated products with a selectivity of 92 mol% in which benzene selectivity was 70 mol%. The superior catalytic activity is attributed to the presence of both H2-activating sites and oxophilic sites. Under the testing conditions, HDO of guaiacol over monometallic molybdenum carbide followed both direct deoxygenation (DDO) and hydrogenation-dehydration (HYD) pathways, while MoWC strongly favored the DDO route. The catalyst remained highly stable over 8h on stream. The electronic interaction between Mo and W in MoWC and their effect on the energetics and mechanism of guaiacol HDO was further explored using first principles Density Functional Theory (DFT) calculations. Our calculations showed that oxygen bonded ~ 1 eV stronger on the bimetallic carbide (MoWC) than on the monometallic molybdenum carbide surface, confirming the enhanced oxophillicity of W in the presence of Mo, in agreement with XPS studies. The observed preferential selectivity towards deoxygenated products on MoWC surfaces was further explained by the mechanistic investigation on MoWC and monometallic molybdenum carbide surfaces. Our calculations showed that the DDO pathway was kinetically favored on the bimetallic MoWC surface (leading to benzene), while the HYD and DDO pathways proceeded with competitive barriers on monometallic molybdenum carbide (leading to both cyclohexene and benzene)

Fast degradation of dyes in water using manganese-oxide-coated diatomite for environmental remediation

By a simple wet-chemical procedure using a permanganate in the acidic medium, diatomite coated with amorphous manganese oxide nanoparticles was synthesized. The structural, microstructural and morphological characterizations of the as-synthesized catalysts confirmed the nanostructure of MnO2 and its stabilization on the support - diatomite. The highly efficient and rapid degradation of methylene blue and methyl orange over synthesized MnO2 coated Diatomite has been carried out. The results revealed considerably faster degradation of the dyes against the previously reported data. The proposed mechanism of the dye-degradation is considered to be a combinatorial effect of chemical, physicochemical and physical processes. Therefore, the fabricated catalysts have potential application in waste water treatment, and pollution degradation for environmental remediation

Acaricidal activity of nishinda (Vitex negundo) leaf and garlic (Allium sativum) bulb extract against red spider mite, Oligonychus coffeae (Acari: Tetranychidae) in tea plantations of Darjeeling hill, West Bengal, India

The red spider mite, Oligonychus coffeae (Nietner) serves as a serious threat to the Darjeeling tea plantations affecting the quality of the leaves. Various plant extracts are currently being researched as an alternative to the chemical pesticides to control the red spider mites. In the present study, the leaves of Vitex negundo L. and the bulb of Allium sativum L. were analyzed for their acaricidal activity on the larval, nymphal and adult stages of the mite. Both the extracts were found to have potent activity against red spider mites and may prove to be potential acaricides in future

Biowaste-derived carbon black applied to polyaniline-based high-performance supercapacitor microelectrodes: Sustainable materials for renewable energy applications

Biowaste, derived from cooking-oven-produced carbon nanoparticles (WCP), are incorporated into polyaniline (PANI) via in-situ chemical oxidative polymerization to achieve excellent electrochemical properties for application in supercapacitors. The WCP-PANI composite electrodes have shown high-performance charge storage, due to combinatorial effect of electrical double layer capacitance from WCP and pseudocapacitance from PANI. With increase in the WCP percolation, work function of PANI is increased, which improves the charge-trapping capabilities of composites. For such distinct charge-trapping mechanism, areal capacitance of the composite microelectrode remains near-constant with increase in scan rate or current density. This indicates the suppression of diffusion limitations at higher scan rates to considerably enhance the rate capability. Also, with increasing polymerization time, strong interaction in this conjugated system greatly improves the charge-transfer reaction between PANI and WCP. The areal capacitance of the composite electrode is found to increase more than 600 times over pure PANI electrode. Moreover, energy-power performance of the microelectrode reveals almost 550% increment in the power density with a mere 1% decrement in energy density. Such rationally synthesized WCP-PANI composite electrodes using biowaste carbon nanomaterials, provide opportunities for the development of next-generation green-supercapacitors with improved energy storage performance.proofpublishe

Fungal systematics and evolution : FUSE 7

publishedVersio

A Novel Copper Chelate Modulates Tumor Associated Macrophages to Promote Anti-Tumor Response of T Cells

At the early stages of carcinogenesis, the induction of tumor specific T cell mediated immunity seems to block the tumor growth and give protective anti-tumor immune response. However, tumor associated macrophages (TAMs) might play an immunosuppressive role and subvert this anti tumor immunity leading to tumor progression and metastasis.The Cu (II) complex, (chelate), copper N-(2-hydroxy acetophenone) glycinate (CuNG), synthesized by us, has previously been shown to have a potential usefulness in immunotherapy of multiple drug resistant cancers. The current study demonstrates that CuNG treatment of TAMs modulates their status from immunosuppressive to proimmunogenic nature. Interestingly, these activated TAMs produced high levels of IL-12 along with low levels of IL-10 that not only allowed strong Th1 response marked by generation of high levels of IFN-gamma but also reduced activation induced T cell death. Similarly, CuNG treatment of peripheral blood monocytes from chemotherapy and/or radiotherapy refractory cancer patients also modulated their cytokine status. Most intriguingly, CuNG treated TAMs could influence reprogramming of TGF-beta producing CD4(+)CD25(+) T cells toward IFN-gamma producing T cells.Our results show the potential usefulness of CuNG in immunotherapy of drug-resistant cancers through reprogramming of TAMs that in turn reprogram the T cells and reeducate the T helper function to elicit proper anti-tumorogenic Th1 response leading to effective reduction in tumor growth

Graphene Solar Cells-Will it be the Ultimate Power Converter?

Solar cells or photovoltaic (PV) cells involve the direct conversion of light energy into electrical energy. PV cells are basically p-n junctions made from layers of semiconducting materials. Under light illumination, either free electron-hole pairs are generated within the bulk of the layers and subsequently separated through the internal electric field across the depletion layer of the junction (in conventional solar cells), or exactions are created and simultaneously separated across a hetero-interface (in excitonic solar cells), thus producing an open-circuited photo voltage [1,2]. Upon connection with an external circuit, an electric current is drawn out and used for powering outside devices. This photocurrent, along with the photo voltage, defines the power that the solar cell can deliver.&nbsp;</p