Studies of aerosols at Delhi

Aerosol size distrib ut ion and conce ntra tion have been measured us ing Ander sen par ticlecascade i-npactor and G.M .W. high vOI.ume sampler respectively. Sampling was done as per the sta bility conditionsof fum igation period. un stable convecuvc con dition s (free rmxmgj a nd the nocturna l sta ble per iod. In the pap er,concentr at ion , size distribu tio n and other relat ed studi es of pa rt iculate mat ter has been reported in the light ofsodar determ ined stability and mixing height of the A8L at Delhi.

Bio-Derived Carbon with Tailored Hierarchical Pore Structures and Ultra-High Specific Surface Area for Superior and Advanced Supercapacitors

We report here on a hollow-fiber hierarchical porous carbon exhibiting an ultra-high specific surface area, synthesized by a facile method of carbonization and activation, using the Metaplexis Japonica (MJ) shell. The Metaplexis Japonica-based activated carbon demonstrated a very high specific surface area of 3635 m2 g−1. Correspondingly, the derived carbonaceous material delivers an ultra-high capacitance and superb cycle life in an alkaline electrolyte. The pore-ion size compatibility is optimized using tailored hierarchical porous carbon and different ion sized organic electrolytes. In ionic liquids nonaqueous based electrolytes we tailored the MJ carbon pore structure to the electrolyte ion size. The corresponding supercapacitor shows a superior rate performance and low impedance, and the device records specific energy and specific power densities as high as 76 Wh kg−1 and 6521 W kg−1, as well as a pronounced cycling durability in the ionic liquid electrolytes. Overall, we suggest a protocol for promising carbonaceous electrode materials enabling superior supercapacitors performance.

Ion Transport through C-butyl-pyrogallol[4]arene-loaded Poly(Vinyl Chloride) Membranes

The present paper studies the natural diffusion and migration of monovalent aqueous ions through pyrogallol[4]arene cavitand-loaded poly(vinyl chloride) solid-state membranes exposed to concentration gradients, and electric fields using electrodes coated with such membranes. We have observed that ion flux through these semipermeable membranes is directly proportional to the amount of macrocycle they contain. Ion size, in this particular case, is not the most important factor to limit ion flux, but solvation numbers and energies seem to play a much more important role in the whole process.

Raman spectra of MCl-Ga2S3-GeS2 (M = Na, K, Rb) glasses

Raman spectra of (MY) x (Ga2S3)0.2−0.2x (GeS2)0.8−0.8x pseudo-ternary glassy systems (M = Na, K, Rb; Y = Cl, Br, I) were investigated systematically as a function of MY nature and alkali content. Raman spectroscopy of the Ga3S3-GeS2 glassy matrix shows a complicated local structure: corner-sharing CS- and edge-sharing ES-GeS4/2 tetrahedra, Ga-S triclusters and ETH-Ga2S6/2 ethane-like units. The Ga2S6/2 population decreases with increasing x related to a substitution of some bridging sulfur atoms around central Ga by terminal Y species with a respective decrease of the network rigidity. The formation of mixed Ga-(S,Y) environment is affected by the M+ ion size and the MY concentration.

Revisiting the chevrel phase: Impact of dispersion corrections on the properties of Mo6S8 for cathode applications

While the Mo6S8 chevrel phase is frequently used as cathode material in Mg--ion batteries, theoretical studies on this material are comparatively scarce. The particular structure of the Mo6S8 phase, with rather loosely connected cluster entities, points to the important role of dispersion forces in this material. However, so far this aspect has been completely neglected in the discussion of Mo6S8 as cathode material for mono- and multivalent-ion batteries. In this work we therefore have studied the impact of dispersion forces on stability and kinetics of Mo6S8 intercalation compounds. For this purpose, a series of charge carriers (Li, Na, K, Mg, Ca, Zn, Al) has been investigated. Interestingly, dispersion forces are observed to only slightly affect the lattice spacing of the chevrel phase, nevertheless having a significant impact on insertion voltage and in particular on the charge carrier mobility in the material. Moreover, upon varying the charge carriers in the chevrel phase, their diffusion barriers are observed to scale linearly with the ion size, almost independent of the charge of the considered ions. This indicates a rather unique and geometry dominated diffusion mechanism in the chevrel phase. The consequences of these findings for the ion mobility in the chevrel phase will be carefully discussed.

Development of Absorbent Using Amylose-Graphite Composite Electrode for Removal of Heavy Metals

Amylose of Phragmites Australis captures heavy metals in a box consisting of sugar chains. However, its absorption rate is low in the period of the month scale. Therefore, the electrochemical driving force was used to promote the absorption rate in this research. Amylose was doped with TiO2 porous graphite electrode. The composted absorbent was characterized using XRD(X-ray diffraction), SEM (Scanning Electrode Microscopy), Raman spectroscopy, and electrochemical methods. The affinity and maximum absorption amount were calculated using the isotherm method. In this study, Pb2+, Cu2+, Cd2+, and Cr6+ were chosen to demonstrate because these heavy metals are significant pollutants in Japan’s surface water. It was found that the maximum absorption was Cu2+ (56.82-mg/L) > Pb2+ (55.89-mg/L) > Cr6+ (53.97-mg/L) > Cd2+ (52.83.68-mg/L) at −0.5 V vs. Ag/AgCl. This is approximately the same order as the hydration radius of heavy metals. In other words, the absorption amounts were determined by the size of heavy metal ions. Subsequently, the mixed heavy metal standard solution was tested; the maximum absorption amount was 21.46 ± 10.03 mg/L. It was inferred that the electrochemical driving force could be shown as the ion size effect in the mixed solution. Despite there being no support for this hypothesis at this time, this study succeeded in showing that the electrochemical driving force can improve the ability of the absorbent.

Ion-size effects on cuprate High Temperature Superconductors

<p>The cuprates are a family of strongly electronically-correlated materials which exhibit high-temperature superconductivity. There has been a vast amount of research into the cuprates since their discovery in 1986, yet despite this research effort, the origins of their electronic phases are not completely understood. In this thesis we focus on a little known paradox to progress our understanding of the physics of these materials. There are two general ways to compress the cuprates, by external pressure or by internal pressure as induced by isovalent-ion substitution. Paradoxically, they have the opposite effect on the superconducting transition temperature. This thesis seeks to understand the salient difference between these two pressures. We study three families of cuprates where the ion size can be systematically altered; Bi₂(Sr₁.₆₋xAx)Ln₀.₄CuO₆₊δ, ACuO₂ and LnBa₂−xSrxCu₃O₇₋δ where Ln is a Lanthenide or Y and A={Mg,Ca,Sr,Ba}. We utilise a variety of techniques to explore different aspects of our paradox, for example; Raman spectroscopy to measure the antiferromagnetic superexchange energy and energy gaps, Density Functional Theory to calculate the density of states, Muon Spin Relaxation to measure the superfluid density as well as a variety of more conventional techniques to synthesize and characterise our samples. Our Raman studies show that an energy scale for spin fluctuations cannot resolve the different effect of the two pressures. Similarly the density of states close to the Fermi-energy, while an important property, does not clearly resolve the paradox. From our superfluid density measurements we have shown that the disorder resulting from isovalent-ion substitution is secondary in importance for the superconducting transition temperature. Instead, we find that the polarisability is a key property of the cuprates with regard to superconductivity. This understanding resolves the paradox! It implies that electron pairing in the cuprates results from either (i) a short-range interaction where the polarisability screens repulsive longer-range interactions and/or (ii) the relatively unexplored idea of the exchange of quantized, coherent polarisation waves in an analogous fashion to phonons in the conventional theory of superconductivity. More generally, we have also demonstrated the utility of studying ion-size effects to further our collective understanding of the cuprates.</p>

Ion-size effects on cuprate High Temperature Superconductors

<p>The cuprates are a family of strongly electronically-correlated materials which exhibit high-temperature superconductivity. There has been a vast amount of research into the cuprates since their discovery in 1986, yet despite this research effort, the origins of their electronic phases are not completely understood. In this thesis we focus on a little known paradox to progress our understanding of the physics of these materials. There are two general ways to compress the cuprates, by external pressure or by internal pressure as induced by isovalent-ion substitution. Paradoxically, they have the opposite effect on the superconducting transition temperature. This thesis seeks to understand the salient difference between these two pressures. We study three families of cuprates where the ion size can be systematically altered; Bi₂(Sr₁.₆₋xAx)Ln₀.₄CuO₆₊δ, ACuO₂ and LnBa₂−xSrxCu₃O₇₋δ where Ln is a Lanthenide or Y and A={Mg,Ca,Sr,Ba}. We utilise a variety of techniques to explore different aspects of our paradox, for example; Raman spectroscopy to measure the antiferromagnetic superexchange energy and energy gaps, Density Functional Theory to calculate the density of states, Muon Spin Relaxation to measure the superfluid density as well as a variety of more conventional techniques to synthesize and characterise our samples. Our Raman studies show that an energy scale for spin fluctuations cannot resolve the different effect of the two pressures. Similarly the density of states close to the Fermi-energy, while an important property, does not clearly resolve the paradox. From our superfluid density measurements we have shown that the disorder resulting from isovalent-ion substitution is secondary in importance for the superconducting transition temperature. Instead, we find that the polarisability is a key property of the cuprates with regard to superconductivity. This understanding resolves the paradox! It implies that electron pairing in the cuprates results from either (i) a short-range interaction where the polarisability screens repulsive longer-range interactions and/or (ii) the relatively unexplored idea of the exchange of quantized, coherent polarisation waves in an analogous fashion to phonons in the conventional theory of superconductivity. More generally, we have also demonstrated the utility of studying ion-size effects to further our collective understanding of the cuprates.</p>