Exceptional modular form of weight 4 on an exceptional domain contained in C27.

Resnikoff [12] proved that weights of a non trivial singular modular form should be integral multiples of 1/2, 1, 2, 4 for the Siegel, Hermitian, quaternion and exceptional cases, respectively. The ?-functions in the Siegel, Hermitian and quaternion cases provide examples of singular modular forms (Krieg [10]). Shimura [15] obtained a modular form of half-integral weight by analytically continuing an Eisenstein series. Bump and Bailey suggested the possibility of applying an analogue of Shimura's method to obtain singular modular forms, i.e. modular forms of weight 4 and 8, on the exceptional domain of 3 x 3 hermitian matrices over Cayley numbers. The idea is to use Fourier expansion of a non-holomorphic Eisenstein series defined by using the factor of automorphy as in Karel [7]. The Fourier coefficients are the product of confluent hypergeometric functions as in Nagaoka [11] and certain singular series which we calculate by the method of Karel [6]. In this note we describe a modular form of weight 4 which may be viewed as an analogue of a ? zero-value and as an application, we consider its Mellin transform and prove a functional equation of the Eisenstein series which is a Nagaoka's conjecture (Nagaoka [11])

Photoeffects at Polycrystalline Tin-Oxide Electrodes

137 p.Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1973.U of I OnlyRestricted to the U of I community idenfinitely during batch ingest of legacy ETD

Microwave-assisted synthesis and characterization of bimetallic PtRu alloy nanoparticles supported on carbon nanotubes

Abstract Multiwalled carbon nanotube (MWCNT) supported PtRu nanoparticles were synthesized by using a microwave-assisted improved impregnation technique. X-ray diffraction, transmission electron microscopy and X-ray photo electron spectroscopy were used to characterize the prepared PtRu/MWCNT nanoparticles. The PtRu nanoparticles with a satisfactory dispersion were formed on the external surface of MWCNTs. The CO stripping experiment was performed to evaluate the poisoning resistance of the prepared PtRu/MWCNT nanoparticles. Results of electrochemical measurements indicate that the prepared PtRu/MWCNTs shows an enhanced performance toward CO poisoning. The results of characterization revealed that microwave-assisted improved impregnation technique have a high yield of alloy phase formation and could be effectively used as a simple, quick and efficient technique for preparation of bimetallic PtRu/MWCNT nanoparticles. © 2015 Elsevier B.V.

A highly sensitive and selective biosensor based on nitrogen-doped graphene for non-enzymatic detection of uric acid and dopamine at biological pH value

Few layered graphene nanosheets were successfully doped with nitrogen through microwave irradiation and thoroughly characterized by using electron microscopy, Raman spectroscopy and X-ray photoelectron spectroscopy. The electrochemical efficiency of N-doped graphene toward enzyme-free detection of uric acid (UA) and dopamine (DA) at neutral pH (7.4) was studied by chronoamperometry and cyclic voltammetry measurements. At working potential of +0.3 V (vs. Ag/AgCl), N-doped graphene electrode revealed ultra-high sensitivity of 2.06 mA mM−1 cm−2 and low limit of detection (LOD) of 0.13 μM within a concentration range of 0 to 0.6 mM for UA detection. Also, at very higher potential of +1.8 V (vs. Ag/AgCl), N-doped graphene sensor exhibited a highly selective response toward DA with very low LOD of 4.5 nM and high sensitivity of 7.63 mA mM−1 cm−2 in a broad linear concentration range from 0.1 to 100 μM. Furthermore, the performance of UA and DA sensors in the real blood sample was satisfactory. © 20181

Spectrophotometric and Electrochemical Study of Cu2+-Selective Azocalix[4]arene Bearing p-Carboxyl group

The spectrophotometric and electrochemical properties of tetraazo(p-carboxy)phenylcalix[4]arene (p-CAC) in the presence of various metal ions were investigated by UV/Vis spectroscopy and voltammetry in CH3CN. p- CAC showed selective color changes to Cu2+ over other metal ions from light orange to colorless, in accordance with hypsochromic shift in UV/Vis spectra. Voltammetric measurements also showed high selectivity for Cu2+.FALS

A new enzyme-free biosensor based on nitrogen-doped graphene with high sensing performance for electrochemical detection of glucose at biological pH value

A new enzyme-free glucose biosensor with high sensing performance was developed based on N-doped graphene for glucose detection at biological pH value. The impact of various N functionalities on glucose sensing performance was investigated. In this regard, three N-doped graphene specimens with various amounts of pyridinic, pyrrolic and quaternary nitrogen functionalities were synthesized and thoroughly characterized for enzyme-free glucose detection. Accordingly, the microwave-treated N-doped sample with large pyridinic nitrogen content exhibited the best glucose sensing performance in terms of a proper limit of detection of 0.13 μM and a high sensitivity of 774.23 μA mM−1 cm−2 in a wide linear range of glucose concentration from 0.13 μM to 14 mM at pH 13. Also, it provided a superior sensitivity of 122.336 μA mM−1 cm−2, an appropriate detection limit of 14.52 μM and a fast linear response within the concentration range of 14.52 μM to 10 mM at biological pH (7.4) value. In addition, no interference was observed with addition of dopamine, ascorbic acid, uric acid, maltose, sucrose and fructose. The results of XPS analysis indicate that the pyridinic N dopants activate the electrocatalytic sites of graphene particles for glucose oxidation reaction. © 2018 Elsevier B.V.1

Performance and stability studies of PtCr/C alloy catalysts for oxygen reduction reaction in low temperature fuel cells

In order to elucidate the reasons for enhanced activity and stability of the alloy catalyst, PtCr/C was prepared by an incipient wetness method and heat-treatments. In single-cell test, the catalysts heat-treated at 900 °C showed the highest performance (about 70% higher than JM Pt/C at 700 mV) because of the alloy effect. Stability of the alloy catalysts was investigated with several accelerated-stress tests. The heavy dissolution of Cr was observed especially in the beginning of operation. The undissolved Cr is considered to take part in the formation of complete alloying. Before and after cell operation, the ratio of Cr to S in the Nafion membrane was measured by EPMA. Within Cr/S of 10% in the Nafion membrane, the conductivity changed a little, but as the Cr/S exceeded more than 10% the serious reduction of conductivity was observed. The catalyst heat-treated at 900 °C showed applicable performance and stability in real cell operations. © 2016 Hydrogen Energy Publications LLC

CO-Tolerant PtMo/C Fuel Cell Catalyst for H-2 Oxidation

CO-tolerant PtMo/C alloy electrocatalyst was prepared by a colloidal method, and its electrocatalytic activity toward CO oxidation was investigated. Electrochemical study revealed that the alloy catalyst significantly enhanced catalytic activity toward the electro-oxidation of CO compared to Pt/C counterpart. Cyclic voltammetry suggested that Mo plays an important role in promoting CO electro-oxidation by facilitating the formation of active oxygen species. The effect of Mo on the electronic structure of Pt was investigated using X-ray absorption spectroscopy to elucidate the synergetic effect of alloying. Our in-depth spectroscopic analysis revealed that CO is less strongly adsorbed on PtMo/C catalyst than on Pt/C catalyst due to the modulation of the electronic structure of Pt d-band. Our investigation shows that the enhanced CO electrooxidation in PtMo alloy electrocatalyst is originated from two factors; one comes from the facile formation of active oxygen species, and the other from the weak interaction between Pt and CO.

Particle Size Control of Pd/C for Improved Electrocatalytic Activity in a Formic Acid Oxidation

Carbon-supported Pd electrocatalyst is prepared by an improved aqueous impregnation method applying a reducing agent of HCHO and an acidic sedimentation promoter of HCl. We investigate the effect of a solution pH on the zeta potential of both Pd particles and carbon support. The opposite sign of zeta potential results in uniform dispersion of Pd on carbon surface without aggregation problem. TEM analysis shows that optimal solution pH of 4.27 adjusted by NaOH provides a mean particle diameter of 3.2 nm with narrow size distribution. Cyclic voltammograms indicate that home-made Pd/C catalyst exhibits significantly higher electrochemical active surface area and better stability compared with commercial 40 wt.% Pd/C in a formic acid oxidation. © 2011 American Scientific Publishers.1

The influence of Co3V2O8 morphology on the oxygen evolution reaction activity and stability

The effect of Co3V2O8 morphology on the electrocatalytic oxygen evolution reaction (OER) activity was evaluated using one- and zero-dimensional nanostructures. The microscopic analyses reveal the existence of thin coating of nitrogen-doped amorphous carbon on the surface of Co3V2O8 nanostructures. The 1D-Co3V2O8 electrocatalyst delivers 10 mA cm−2 at overpotential of 0.350 V versus reversible hydrogen electrode for OER in 0.1 M KOH, whereas 0D-Co3V2O8 catalyst showed 0.397 V, benefited from the morphological characteristics of 1D. Moreover, the 1D-Co3V2O8 catalyst exhibits much lower OER overpotential than that of commercial noble metal oxide catalysts, RuO2 (0.41 V) and Pt/C (0.79 V). Keywords: Oxygen evolution reaction, Electrocatalysis, Co3V2O8, Electrospinning, Nitrogen-doped carbo