Quantum electrodynamical theory of high-efficiency excitation energy transfer in laser-driven nanostructure systems

A fundamental theory is developed for describing laser-driven resonance energy transfer (RET) in dimensionally constrained nanostructureswithin the framework of quantum electrodynamics. The process of RET communicates electronic excitation between suitably disposed emitter and detector particles in close proximity, activated by the initial excitation of the emitter. Here, we demonstrate that the transfer rate can be significantly increased by propagation of an auxiliary laser beam through a pair of nanostructure particles. This is due to the higher order perturbative contribution to the F¨orster-type RET, in which laser field is applied to stimulate the energy transfer process. We construct a detailed picture of how excitation energy transfer is affected by an off-resonant radiation field, which includes the derivation of second and fourth order quantum amplitudes. The analysis delivers detailed results for the dependence of the transfer rates on orientational, distance, and laser intensity factor, providing a comprehensive fundamental understanding of laser-driven RET in nanostructures. The results of the derivations demonstrate that the geometry of the system exercises considerable control over the laser-assisted RET mechanism. Thus, under favorable conformational conditions and relative spacing of donor-acceptor nanostructures, the effect of the auxiliary laser beam is shown to produce up to 70% enhancement in the energy migration rate. This degree of control allows optical switching applications to be identified

Controlling resonance energy transfer in nanostructure emitters by positioning near a mirror

The ability to control light-matter interactions in quantum objects opens up many avenues for new applications. We look at this issue within a fully quantized framework using a fundamental theory to describe mirror-assisted resonance energy transfer (RET) in nanostructures. The process of RET communicates electronic excitation between suitably disposed donor and acceptor particles in close proximity, activated by the initial excitation of the donor. Here, we demonstrate that the energy transfer rate can be significantly controlled by careful positioning of the RET emitters near a mirror. The results deliver equations that elicit new insights into the associated modification of virtual photon behavior, based on the quantum nature of light. In particular, our results indicate that energy transfer efficiency in nanostructures can be explicitly expedited or suppressed by a suitably positioned neighboring mirror, depending on the relative spacing and the dimensionality of the nanostructure. Interestingly, the resonance energy transfer between emitters is observed to “switch off” abruptly under suitable conditions of the RET system. This allows one to quantitatively control RET systems in a new way

Feeding Patterns and Milk Production of Small-Scale Dairy Farmers under Semi-Intensive and Extensive Cattle Management Systems in Sri Lanka

The main objective of the present study was to determine the feeding pattern and milk production of small-scale dairy farmers under semi-intensive and extensive management systems in the intermediate zone of Sri Lanka. This region is sandwiched between the Wet and Dry Zones, receives a mean annual rainfall of 1750-2500 mm, and covers an area of about 1.2 million ha. A survey was conducted with 60 farmers and data on their herd size, herd composition and breeds, management system, breeding method, milk production, feeding costs and returns of raising animals were collected. The results indicated that the majority of farmers conducted dairying as a part-time business in both semi-intensive (80%) and extensive (66%) management systems in the study area. The highest (P \u3c 0.05) average herd size was observed under semi-intensive systems (3.7 animal units (AU)), compared to extensive systems (2.7 AU). The farmers under the semi-intensive system maintained better feeding levels compared with the extensive system. The majority of farmers in the area depended on tethering and stall feeding as their main source of animal feed. Grasses grown on roadsides, paddy fields, neighbours’ land, government estates and tree leaves were the main feed resources available for both management systems. Rice (Oriza sativa) bran and coconut (Cocos nucifera) poonac were the main concentrate feed ingredients in the study area. Jersey crosses were the most popular dairy animals among semi-intensively managed farms, whereas Sahiwal crosses were most popular in extensive management systems. The average milk production under extensive systems was significantly lower (P \u3c 0.01) at 3.9 l/AU/day, compared to 5.4 l/AU/day under semi-intensive systems. Semi-intensive management systems also had the highest average monthly return per AU

Silage Characteristics of Sugarcane (\u3cem\u3eSacchrum officinarum\u3c/em\u3e) Tops in Sri Lanka

Sugarcane tops (SCTs) is generally known to be a major byproduct of sugarcane industry which is currently not utilized in a profitable manner and it is widely available at low cost particularly during the dry period in Sri Lanka when the forage are scarce for feeding of ruminants. Usually, the residue after sugarcane harvesting contains dry leaves, fresh leaves and growing point of the stalk. It increases drying of leaves in the field within 2 to 3 days after harvesting due to dry weather conditions prevailing in the harvesting period and much of the tops are burned and wasted in the field. Therefore, it is difficult to use tops as feed unless they are preserved. Silage making is a good preservation technique which can be used under this condition. Therefore, the objective of this study was to compare the ensiling characteristics and nutritive value of SCTs or Guinea (Panicum maximum) ‘A’ grass with different additives

Customer Behavior Analysis for Social Media

It is essential for a business organization to get the customer feedback in order to grow as a company. Business organizations are collecting customer feedback using various methods. But the question is ‘are they efficient and effective?' In the current context, there is more of a customer oriented market and all the business organizations are competing to achieve customer delight through their products and services. Social Media plays a huge role in one's life. Customers tend to reveal their true opinion about certain brands on social media rather than giving routine feedback to the producers or sellers. Because of this reason, it is identified that social media can be used as a tool to analyze customer behavior. If relevant data can be gathered from the customers' social media feeds and if these data are analyzed properly, a clear idea to the companies what customers really think about their brand can be provided

Enhancing Performance of SnO 2

Although liquid electrolyte based dye-sensitized solar cells (DSCs) have shown higher photovoltaic performance in their class, they still suffer from some practical limitations such as solvent evaporation, leakage, and sealing imperfections. These problems can be circumvented to a certain extent by replacing the liquid electrolytes with quasi-solid-state electrolytes. Even though SnO2 shows high election mobility when compared to the semiconductor material commonly used in DSCs, the cell performance of SnO2-based DSCs is considerably low due to high electron recombination. This recombination effect can be reduced through the use of ultrathin coating layer of ZnO on SnO2 nanoparticles surface. ZnO-based DSCs also showed lower performance due to its amphoteric nature which help dissolve in slightly acidic dye solution. In this study, the effect of the composite SnO2/ZnO system was investigated. SnO2/ZnO composite DSCs showed 100% and 38% increase of efficiency compared to the pure SnO2-based and ZnO-based devices, respectively, with the gel electrolyte consisting of LiI salt

High Efficient Dye-Sensitized Solar Cells Based on Synthesized SnO 2

In this study, SnO2 semiconductor nanoparticles were synthesized for DSC applications via acid route using tin(ii) chloride as a starting material and hydrothermal method through the use of tin(iv) chloride. Powder X-ray diffraction studies confirmed the formation of the rutile phase of SnO2 with nanoranged particle sizes. A quasi-solid-state electrolyte was employed instead of a conventional liquid electrolyte in order to overcome the practical limitations such as electrolyte leakage, solvent evaporation, and sealing imperfections associated with liquid electrolytes. The gel electrolytes were prepared incorporating lithium iodide (LiI) and tetrapropylammonium iodide (Pr4N+I−) salts, separately, into the mixture which contains polyacrylonitrile as a polymer, propylene carbonate and ethylene carbonate as plasticizers, iodide/triiodide as the redox couple, acetonitrile as the solvent, and 4-tertiary butylpyridine as an electrolyte additive. In order to overcome the recombination problem associated with the SnO2 due to its higher electron mobility, ultrathin layer of CaCO3 coating was used to cover the surface recombination sites of SnO2 nanoparticles. Maximum energy conversion efficiency of 5.04% is obtained for the device containing gel electrolyte incorporating LiI as the salt. For the same gel electrolyte, the ionic conductivity and the diffusion coefficient of the triiodide ions are 4.70 × 10−3 S cm−1 and 4.31 × 10−7 cm2 s−1, respectively

The levels of Brachyspira hyodysenteriae binding to porcine colonic mucins differ between individuals, and binding is increased to mucins from infected pigs with de novo MUC5AC synthesis

Brachyspira hyodysenteriae colonizes the pig colon, resulting in mucohemorrhagic diarrhea and growth retardation. Fecal mucus is a characteristic feature of swine dysentery; therefore, we investigated how the mucin environment changes in the colon during infection with B. hyodysenteriae and how these changes affect this bacterium's interaction with mucins. We isolated and characterized mucins, the main component of mucus, from the colon of experimentally inoculated and control pigs and investigated B. hyodysenteriae binding to these mucins. Fluorescence microscopy revealed a massive mucus induction and disorganized mucus structure in the colon of pigs with swine dysentery. Quantitative PCR (qPCR) and antibody detection demonstrated that the mucus composition of pigs with swine dysentery was characterized by de novo expression of MUC5AC and increased expression of MUC2 in the colon. Mucins from the colon of inoculated and control pigs were isolated by two steps of isopycnic density gradient centrifugation. The mucin densities of control and inoculated pigs were similar, whereas the mucin quantity was 5-fold higher during infection. The level of B. hyodysenteriae binding to mucins differed between pigs, and there was increased binding to soluble mucins isolated from pigs with swine dysentery. The ability of B. hyodysenteriae to bind, measured in relation to the total mucin contents of mucus in sick versus healthy pigs, increased 7-fold during infection. Together, the results indicate that B. hyodysenteriae binds to carbohydrate structures on the mucins as these differ between individuals. Furthermore, B. hyodysenteriae infection induces changes to the mucus niche which substantially increase the amount of B. hyodysenteriae binding sites in the mucus

Estimating glomerular filtration rate in diabetes: a comparison of cystatin-C-and creatinine-based methods

Abstract Aims/hypothesis: We compared the predictive performance of a GFR based on serum cystatin C levels with commonly used creatinine-based methods in subjects with diabetes. Subjects, materials and methods: In a crosssectional study of 251 consecutive clinic patients, the mean reference (plasma clearance of 99m Tc-diethylene-triaminepenta-acetic acid) GFR (iGFR) was 88±2 ml min . A regression equation describing the relationship between iGFR and 1/cystatin C levels was derived from a test population (n=125) to allow for the estimation of GFR by cystatin C (eGFR-cystatin C). The predictive performance of eGFR-cystatin C, the Modification of Diet in Renal Disease 4 variable formula (MDRD-4) and Cockcroft-Gault (C-G) formulas were then compared in a validation population (n=126). Results: There was no difference in renal function (ml min −1 1.73 m −

Deciphering the intracellular metabolism of Listeria monocytogenes by mutant screening and modelling

Background: The human pathogen Listeria monocytogenes resides and proliferates within the cytoplasm of epithelial cells. While the virulence factors essentially contributing to this step of the infection cycle are well characterized, the set of listerial genes contributing to intracellular replication remains to be defined on a genome-wide level. Results: A comprehensive library of L. monocytogenes strain EGD knockout mutants was constructed upon insertion-duplication mutagenesis, and 1491 mutants were tested for their phenotypes in rich medium and in a Caco-2 cell culture assay. Following sequencing of the plasmid insertion site, 141 different genes required for invasion of and replication in Caco-2 cells were identified. Ten in-frame deletion mutants were constructed that confirmed the data. The genes with known functions are mainly involved in cellular processes including transport, in the intermediary metabolism of sugars, nucleotides and lipids, and in information pathways such as regulatory functions. No function could be ascribed to 18 genes, and a counterpart of eight genes is missing in the apathogenic species L. innocua. Mice infection studies revealed the in vivo requirement of IspE (Lmo0190) involved in mevalonate synthesis, and of the novel ABC transporter Lmo0135-0137 associated with cysteine transport. Based on the data of this genome-scale screening, an extreme pathway and elementary mode analysis was applied that demonstrates the critical role of glycerol and purine metabolism, of fucose utilization, and of the synthesis of glutathione, aspartate semialdehyde, serine and branched chain amino acids during intracellular replication of L. monocytogenes. Conclusion: The combination of a genetic screening and a modelling approach revealed that a series of transporters help L. monocytogenes to overcome a putative lack of nutrients within cells, and that a high metabolic flexibility contributes to the intracellular replication of this pathogen