Performance analysis of an interacting quantum dot thermoelectric system

We analyze the nanocaloritronic performance of an interacting quantum dot that is subject to an applied bias and an applied temperature gradient. It is now well known that, in the absence of phonon contribution, a weakly coupled non-interacting quantum dot can operate at thermoelectric efficiencies approaching the Carnot limit. However, it has also been recently pointed out that such peak efficiencies can only be achieved when operated in the reversible limit, with a vanishing current and hence a vanishing power output. In this paper, we point out three fundamental results affecting the thermoelectric performance due to the inclusion of Coulomb interactions: a) The reversible operating point carries zero efficiency, b) operation at finite power output is possible even at peak efficiencies approaching the Carnot value, and c) the evaluated trends of the the maximum efficiency deviate considerably from the conventional {\it{figure of merit}} $zT$ based result. Finally, we also analyze our system for thermoelectric operation at maximum power output.Comment: 10 pages, 6 figures, Resubmission- to be published in Phys. Rev.

Cold Caustic Soda Pulping of Eucalyptus Saligna

A survey has been prepared covering the literature on the cold caustic soda pulping of Eucalyptus saligna. The survey was broadened to include pulping of all species of Eucalyptus by this particular process. Experimental pulping of Eucalyptus saligna by the cold caustic soda process under a variety of conditions as well as pulping of aspen wood under one condition led to the following conclusions: (a) Eucalyptus saligna is suitable for the manufacture of cold caustic soda pulp. (b) alkali concentration of 30 grams per liter on full size chips of Eucalyptus saligna produces the best strength properties and fairly good yield. (c) The use of crushed chips is not advisable at higher alkali concentrations since a loss of strength results. Where low alkali concentrations are used, the crushing of chips improves liquor penetration with a reduction in the quantity of screen rejects. (d) In no case did the Eucalyptus pulps reach the strength of aspen pulp under the conditions of the experiment

Accurate estimation of low [< (10^-8) ohm . cm²] values of specific contact resistivity

Advancements in nanotechnology have created the need for efficient means of communication of electrical signals to nanostructures, which can be addressed using low resistance contacts. In order to study and estimate the resistance of such contacts or the resistance posed by the interface(s) in such contacts, accurate test structures and evaluation techniques need to be used. The resistance posed by an interface is quantified using its specific contact resistivity (SCR), and although multiple techniques have been utilized, inaccuracies of such techniques in measuring values of SCR lesser than ( < 10-8 Ω ldr cm2 ) have been reported. In this letter, an approach for estimating very low values of SCR (lower than the previously limiting ( < 10-8 Ω ldr cm2 )) using a cross Kelvin resistor test structure is demonstrated using aluminum to titanium silicide ohmic contacts, with a minimum estimated SCR value of 6.0 times 10-10 Ω ldr cm2

RF magnetron sputtered perovskite-oriented PSZT thin films on gold for piezoelectric and ferroelectric transducers

Conditions for depositing perovskite-oriented Pb0.92Sr0.08(Zr0.65Ti0.35) O-3 thin films on gold by RF magnetron sputtering are investigated. Deposition results were analysed by scanning electron microscopy, X-ray photoelectron spectroscopy and X-ray diffractometry. It was found that the desired perovskite phase can be obtained at a substrate temperature of 300 degrees C, much lower than the typically reported 650 degrees C for deposition on platinum

A comparative study of postoperative complications of lightweight mesh and conventional prolene mesh in Lichtenstein hernia repair

Background:  Inguinal hernia repair is the most frequently performed operation in any general surgical unit. The complications of using the mesh has been the rationale to examine the role of mesh in hernia repair in detail and to begin investigating the biocompatibility of different mesh modifications and to challenge old mesh concepts. Therefore the present study is undertaken to compare the lightweight mesh (Ultrapro) with conventional prolene mesh in lichtenstein hernia repair. Methods: Thirty one patients with primary unilateral inguinal hernia was subjected either to lightweight mesh Lichtenstein’s hernioplasty or standard prolene mesh Lichtenstein’s hernioplasty. The patients were followed in the surgical OPD at 1 month, 6 months and 1 year for time taken to return to normal activities, chronic groin pain, foreign body sensation, seroma formation and recurrence.Results: Chronic pain among patients in standard prolene mesh group at 1 month, 6 month, and 1 year follow up was seen in 45.2%, 16% and 3.2% of the patients respectively, in light weight mesh group patients at 1 month, 6 month and 1 year follow up was 32.2%, 6.4% and none at one year respectively.   Foreign body sensation in the light weight mesh group is significantly less compared to patients in standard prolene mesh group. Time taken to return to work was relatively shorter among patients in Light weight mesh group. There was no recurrence in both groups.Conclusion:  Light weight mesh is an ideal choice in Lichenstein’s hernioplasty whenever feasible.

Growth of Al<SUB>2</SUB>O<SUB>3</SUB>/Al composites from Al-Zn alloys

Observations are presented here of the initiation and growth of an Al2O3composite by the directed oxidation of a molten binary Al-Zn alloy with and without preforms. The oxidation behaviour into free space begins with the formation of ZnO on the melt surface followed by a second stage of relatively high growth rate associated with the constant presence of ZnO and a final region of slow growth rate during which the surface consists of both ZnO as well as Al2O3. Composite formation is explained on the basis of a cyclic formation and reduction by molten aluminium of ZnO. Oxidation was carried out with ternary Mg additions into Al2O3 preforms of different particle sizes. The infiltration of an Al2O3 preform is governed by reaction induced wetting between alloy and ZnO. Nucleation of the alumina is epitaxial with respect to particles of the preform and growth rates are higher than that for composite growth into free space

Nanoscale characterization of energy generation from piezoelectric thin films

We report on the use of nanoindentation to characterize in situ the voltage and current generation of piezoelectric thin films. This work presents the controlled observation of nanoscale piezoelectric voltage and current generation, allowing accurate quantification and mapping of force function variations. We characterize both continuous thin films and lithographically patterned nanoislands with constrained interaction area. The influence of size on energy generation parameters is reported, demonstrating that nanoislands can exhibit more effective current generation than continuous films. This quantitative finding suggests that further research into the impact of nanoscale patterning of piezoelectric thin films may yield an improved materials platform for integrated microscale energy scavenging systems

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