Band Edge Emission Improvement by Energy Transfer in HybridⅢ-Nitride/Organic Semiconductor Nanostructure

GaN nanorods are fabricated using inductively coupled plasma etching with Ni nano-island masks. The poly [2- methoxy-5-（2-ethyl）hexoxy-l,4-phenylenevinylene] （MEH-PPV）/GaN-nanorod hybrid structure is fabricated by depositing the MEH-PPV film on the GaN nanorods by using the spin-coating process. In the hybrid structure, the spatial separation is minimized to achieve high-emciency non-radiative resonant energy transfer. Optical properties of a novel device consisting of MEH-PPV/GaN-nanorod hybrid structure is studied by analyzing photoluminescenee （PL） spectra. Compared with the pure GaN nanorods, the PL intensity of the band edge emission of GaN in the MEH-PPV/GaN-nanorods is enhanced as much as three times, and the intensity of the yellow band is suppressed slightly. The obtained results are analyzed by energy transfer between the GaN nanorods and the MEH-PPV. An energy transfer model is proposed to explain the phenomenon.

Improvement in the calculation of anti-Stokes energy transfer and experimental justification based on Er_(0.01)Yb_xY_(1 0.01 x)VO_4 crystal

The improvement on the calculation of anti-Stokes energy transfer rate is studied in the present work. The additional proportion coefficient between Stokes and anti-Stokes light intensities of quantum Raman scattering theory as compared with the classical Raman theory is introduced to successfully describe the anti-Stokes energy transfer. The theoretical formula for the improvement on the calculation of anti-Stokes energy transfer rate is derived for the first time in this study. The correctness of introducing coefficient exp{△E/kT} from well-known Raman scatter theory is demonstrated also. Moreover, the experimental lifetime measurement in Er0.01YbxY1-0.01-xVO4 crystal is performed to justify the validity of our important improvement in the original phonon-assisted energy transfer theory for the first time.

Boosting energy-storage capability in carbon-based supercapacitors using low-temperature water-in-salt electrolytes

Supercapacitors(SCs) are high-power energy storage devices with ultra-fast charge/discharge properties.SCs using concentrated aqueous-based electrolytes can work at low temperatures due to their intrinsic properties, such as higher freezing point depression(FPD) and robustness. Besides the traditional organic-and aqueous-based(salt-in-water) electrolytes used in SCs, water-in-salt(WISE) sodium perchlorate electrolytes offer high FPD, non-flammability, and low-toxicity conditions, allowing the fabrication of safer, environmentally friendly, and more robust devices. For the first time, this work reports a comprehensive study regarding WISE system’s charge-storage capabilities and physicochemical properties under low-temperature conditions(T < 0 ℃) using mesoporous carbon-based electrodes. The effect of temperature reduction on the electrolyte viscosity and electrical properties was investigated using different techniques and the in-situ(or operando) Raman spectroscopy under dynamic polarization conditions.The cell voltage, equivalent series resistance, and specific capacitance were investigated as a function of the temperature. The cell voltage(U) increased ~ 50%, while the specific capacitance decreased ~20%when the temperature was reduced from 25 ℃ to -10 ℃. As a result, the maximum specific energy(E = CU^(2)/2) increased ~ 100%. Therefore, low-temperature WISEs are promising candidates to improve the energy-storage characteristics in SCs.

Improved anti-Stokes energy transfer between rare earth ions in Er(0.5)Yb(9.5):FOV oxyfluoride vitroceramics explains the strong color reversal

The widely used energy transfer theory is a foundation of luminescence, in which the rates of Stokes and anti-Stokes processes have the same calculation formula. An improvement on the anti-Stokes energy transfer to explain the fluorescence intensity reversal between the red and green fluorescence of Er（0.5）Yb（9.5）：FOV is reported in the present article. The range of the intensity reversal Z was measured to be 877. Dynamic processes for 16 levels were simulated. A coefficient, the improvement factor of the intensity ratio of Stokes to anti-Stokes processes in quantum Raman theory compared to classical Raman theory, is introduced to successfully describe the anti-Stokes energy transfer. A new method to calculate the distance between the rare earth ions, which is critical for the energy transfer calculation, is proposed. The validity of these important improvements is also proved by experiment.

A Systems Approach for Analyzing Vegetative and Soil Degradation in Arnigad Micro-watershed of Indian Himalayan Region

This study analyzes the vegetative and soil degradation,measured as biomass and soil loss,for Arnigad micro-watershed located in Indian Himalayan state of Uttarakhand,in systems framework by using dynamic linear programming bio-economic model.The focus is at investigating the effects of alternate policy regimes,i.e.,introduction of improved energy sources for cooking along with substitution of existing local livestock breeds with improved breed,reduction in human population growth and introduction of high yielding varieties of main crops including paddy,maize and wheat.The model horizon extended over a period of 25 years,i.e.,from 2006 to 2030.It was found that the model scenario incorporating increased use of improved energy sources along with substitution of local cows by improved cows could be the most effective policy option in reducing vegetative and soil degradation.The vegetative biomass density declined to 19.76% compared to 35.24% in the BASE scenario and soil erosion loss was also lowered by 29.13%.Also,the reduction of population growth rate to half of the BASE scenario led to minor improvements in degradation.Introduction of high yielding varieties of main crops slightly increased vegetative degradation but reduced soil loss(8.35%) with respect to the BASE scenario.Such a phenomenon could be explained in terms of changed crop mix resulting in reduced amount of crop by-products requiring increased lopping of tree branches for animal fodder.The policy option of the increased use of improved energy sources along with substitution of improved breed of cows resulted in 9.58% higher income.Introduction of high yielding varieties of crops led to 1.92% increase in income,but the income decreased by 1.25 % when population growth was reduced to half.The usefulness of the model lies in analyzing the systems behavior in its entirety where the results can predict the possible direction of change as a result of manipulation in alternate economic regimes.

Restoration of modern buildings Grazia Lombardo

The present paper is part of a research that is devetoped within the sustainable building design through the revisiting of the traditional construction materials. The results obtained show that the naturat stone, enhanced by technoLogicaL innovations, are often capable of providing excellent performance. Based on the tests, it was possible to verify and validate the hypothesis that the proposed new system of external vertical opaque enclosure consisting in a panel in dry-assembled and pre- compressed blocks of natural stone through reinforcing steel has good performances when used both in the case of new design and in the case of recovery of modern buildings, when the intervention is being addressed within of an overaLL building improvement regarding the security, sustainabiLity, functionality and image. This paper reports the first results obtained by the study of the feasibility of the envelope being tested, through the definition of alL the detaits of links with the existing building structure.

Role of solar power in shifting the Turkish electricity sector towards sustainability

This work covers a three-stage evaluation:cradle-to-grave life-cycle assessment(LCA)of polycrystalline silicon(pc-Si)and monocrys-talline silicon(mc-Si)solar photovoltaics(PVs)as on-grid utility-scale energy options;environmental-impact distribution of pc-Si and mc-Si combinations under local conditions in Turkey;and assessment of the role of solar power in improving the environmental per-formance of the Turkish electricity mix.In LCA,mc-Si panels are found to have 4.47-9.16%higher environmental impacts than pc-Si panels in absolute terms.However,the higher efficiency and slower degradation rate of mc-Si panels make them have lower impacts on a kWh electricity basis.For the solar PV combination,the global-warming potential(GWP)and human-toxicity potential(HTP)re-sults are found to be significantly lower than that of home-scale pc-Si systems(27.1-34.4 g versus 33.7-59.9 g CO_(2) equivalent(eq)/kWh 30.6-38.9 g versus 65.9-117 g 1-4 dichlorobenzene(g 1-4 DB)eq/kWh)operating in Turkey due to the higher capacity and efficiency of the utility-scale system.This result reveals the advantage of utilizing solar power as a centralized energy option for the country.All of the eight impacts that we evaluated reduce increasingly with increasing solar percentage in the electricity mix.The general ten-dency is that each percentage increase in solar electricity in the mix reduces each impact by~1.0%.With a conservative assumption,if the solar power ratio in the mix increases to 15%by 2030,a GWP reduction of 31.3 million tons can be achieved.This corresponds to 12.7%of the greenhouse-gas mitigation commitment(246 million tons CO_(2) eq)made by Turkey under the United Nations Framework Convention on Climate Change.With the Turkish electricity sector being dominated by imported coal and natural gas,the obtained results reveal the potential of solar power in improving the environmental performance of the electricity mix in Turkey.