924 research outputs found
Effects of sintering temperature on the magnetoresistance and microstructure of the mixture of Fe3O4 and Cu-ferrite powder
No full textSynthesis of PMMA-b-PBA Block Copolymer in Homogeneous and Miniemulsion Systems by DPE Controlled Radical Polymerization
No full textHIGH RESOLUTION FOURIER TRANSFORM EMISSION SPECTROSCOPY OF YH AND YD.
No full textAuthor Institution: Department of Chemistry, University of Arizona; Department of Chemistry, University of WaterlooThe electronic emission spectrum of YH and YD has been investigated in the 690 nm to 3 spectral region using a Fourier transform spectrometer. The YH and YD bands were excited in an yttrium hollow cathode lamp operated with neon gas and a trace of of The observed bands have been classified into three different electronic transitions; and . The transition of YD could not be identified due to its very weak intensity. The rotational analysis of several bands of the transition (up to for YH and for YD) provides improved equilibrium vibrational and rotational constants for the ground state of YH and YD. The excited state is involved in several perturbations
Synthesis of Porphyrins with an Electron-Donating Group for Dye-Sensitized Solar Cells
No full text我們已經成功合成出在紫質meso位置引入具推電子基的鋅紫質染料，進而應用於太陽能電池中。當引入具推電子基時將影響紫質的光譜、電化學和光電性。這一系列的鋅紫質染料中比YD-0的吸收光譜中我們可以發現Soret bands 和Q bands 有明顯的變寬及紅位移的現象，尤其以在meso位置接上triarylamine的紫質YD-7與YD-8更為明顯。且引入推電子基後，其HOMO-LUMO的能階差將減少。紫質YD-1-YD-4經由理論計算的結果電子為繞在紫質與amino group之間，而第一氧化態出現在diarylamine上，經由測試其光電結果中這些紫質將有不錯的表現。又以紫質YD-11的光電轉換率為6.57%為最佳。Novel porphyrin dyes with an electron-donating group (EDG) attached on a meso-position have been designed and synthesized for use as sensitizers in dye-sensitized solar cells (DSSC). The nature of the EDG shows significant influences on the spectral, electrochemical and photovoltaic properties of these sensitizers. Absorption spectra of porphyrins having an amino group show broadened Soret band and red-shifted Q bands with respect to those of reference porphyrin YD-0. This phenomenon is more pronounced for porphyrins YD-7 and YD-8 that have a pi-conjugated triphenylamine at the meso-position opposite the anchoring group. Upon introduction of an EDG at the meso-position, the potential for the first oxidation alters significantly to the negative and that for the first reduction does not significantly change, indicating a decreased HOMO-LUMO gap. Quantum-chemical (DFT) results support the spectroelectrochemical data for a delocalization of charge between the porphyrin ring and the amino group in the first oxidative state of diarylamino-substituted porphyrin YD-1-YD-4, which exhibit better photovoltaic performance among all porphyrins under investigation. With the long-chain hydrocarbon groups on the diarylamino substituent, YD-11 shows the best cell performance with ISC = 13.42 mA cm-2, VOC = 0.71 V, and FF = 0.69, giving an overall power conversion efficiency 6.57 % under simulated one-sun AM1.5 illumination.第一章 緒論
1-1 紫質簡介………………………………………………….....1
1-2 紫質吸收光譜原理………………………………………….3
1-3 染料敏化太陽能電池的發展……………………………….7
1-4 染料敏化太陽能電池相關文獻回顧………………………15
1-5 研究動機與方向……………………………………………24
第一章 文獻回顧……………………………………………….26
第二章 紫質合成
2-1 紫質及其衍生物的合成……………………………………29
2-2 鋅紫質染料的合成………………………………………....39
第一章 文獻回顧….……………………………………………42
第三章 結果與討論
3-1 UV-vis光譜比較……………………………………………..43
3-2電化學………………………………………………………..45
3-3敏化太陽能電池之結果與討論 ……………………………54
第四章 結論…………………………………………………………57
第五章 未來展望…………………………………………………...58
第六章 實驗步驟
6-1 藥品與儀器………………………………………………...59
6-2 實驗步驟…………………………………………………...62
附錄…………………………………………………………………....80
圖目錄
Fig.1-1-1 (a)紫質基本架構 (b) 血紅素活性中心(c) 葉綠素(Chlorophyll-a)的活性中心………………………………………1
Fig.1-2-2 Porphyrin四軌域理論分子軌域……………………………..5
Fig.1-2-3 H2TPP，ZnTPP的吸收光譜....................................................6
Fig.1-2-4 紫質中電子在不同 (a)軌域 (b)能態 間的躍遷示意圖……6
Fig.1-3-1 DSSC的組成及電子循環機制...............................................12
Fig.1-3-2 DSSC與p-n型太陽能電池的比較........................................13
Fig.1-4-1 一些應用在染料敏化太陽能電池上光電轉換率大於10%的Ru-polypyridyl dyes.................................................................................15
Fig.1-4-2 具有electron-donor groups的染料，(a) porphyrin dye及(b) Ru dye N845..................................................................................................16
Fig.1-4-3 具推電子基的染料以及具四個羧酸基的紫質染料………17
Fig.1-4-4 porphyrin dye............................................................................18
Fig.1-4-5 一些具有羧酸基或磷酸基的紫質染料結構...................18
Fig.1-4-6 β位置的紫質染料衍生物.....................................................20
Fig.1-4-7 利用雜環連接羧酸基與紫質的染料.....................................21
Fig.1-4-8 molecular orbital.......................................................................22
Fig.1-4-9 電子轉移的可能路徑示意圖……………………………….23
Fig. 1-4-10不對稱紫質染料……………………………………………23
Scheme 2-1-1 Dipyrromethane(1)之合成............................................29
Scheme 2-1-2 Aldehyde(4)之合成...........................................................29
Scheme 2-1-3 Porphyrin(9)………………………..................................30
Scheme 2-1-4 Porphyrin(10)………………………................................31
Scheme 2-1-5 Porphyrin(12)之合成........................................................32
Scheme 2-1-6 Diarylamine(5)與(6)之合成…………………………......33
Scheme 2-1-8 Porphyrin(13)及porphyrin(14)之合成.............................34
Scheme 2-1-9 Porphyrin(15)及porphyrin(16)之合成.............................35
Scheme 2-1-10 Porphyrin(17)之合成…………………………………..36
Scheme 2-1-11 Porphyrin(18)及porphyrin(19)合成...............................36
Scheme 2-1-10 化合物(21)之合成……………………………...……..37
Scheme 2-1-11 porphyrin(23)合成..........................................................38
Scheme 2-1-11 porphyrin(25)合成..........................................................39
Scheme 2-2-1 Porphyrin(YD-1)、Porphyrin(YD-2)與Porphyrin(YD-11)
之合成………………………………………………………………......40
Scheme 2-2-2 Porphyrin(YD-3)、Porphyrin(YD-4)之合成……………41
Scheme 2-2-3 Porphyrin(YD-5)之合成…………………...…………....41
Fig. 3-1-1 Porphyrin dye……………………………. …………………43
Fig. 3-1-2 Porphyrin dye UV-vis absorption spectra...............................44
Fig. 3-1-3化合物TTBPZn與(YD-1)-(YD-5)的UV-vis absorption ...45
Fig. 3-2-0 The cyclic voltammograms of compound YD-0 in DCM containing 0.1 M TBAPF6 at 273 K.........................................................47
Fig. 3-2-1 The cyclic voltammograms of compound YD-1 in DCM
containing 0.1 M TBAPF6 at 298 K…………………………………….47
Fig. 3-2-2 The cyclic voltammograms of compound YD-2 in DCM containing 0.1 M TBAPF6 at 298 K…………………………………….48
Fig. 3-2-3 The cyclic voltammograms of compound YD-3 in DCM containing 0.1 M TBAPF6 at 298 K……………………………………48
Fig. 3-2-4 The cyclic voltammograms of compound YD-4 in DCM containing 0.1 M TBAPF6 at 298 K……………………………………49
Fig. 3-2-5 The cyclic voltammograms of compound YD-5 in DCM containing 0.1 M TBAPF6 at 298 K……………………………………49
Fig. 3-2-6 The cyclic voltammograms of compound YD-6 in DCM containing 0.1 M TBAPF6 at 298 K……………………………………50
Fig. 3-2-7 The cyclic voltammograms of compound YD-7 in DCM containing 0.1 M TBAPF6 at 298 K……………………………………50
Fig. 3-2-8 The cyclic voltammograms of compound YD-8 in DCM containing 0.1 M TBAPF6 at 298 K……………………………………51
Fig. 3-2-9 A schematic energy level diagram of porphyrins …………53
Fig. 3-3-1(a)Current density vs. voltage characteristic of photovoltaic devices. (b) Photovoltaic performance of dye-sensitized cells usingdifferent Zn porphyrins as sensitizers and N719(M`)
…………………………………………………………………………..54
Fig. 3-3-2 IPCE vs Wavelength...............................................................55
表目錄
Table 1-4-1 一些具有羧酸或磷酸基的鋅紫質或銅紫質……………..19
Table 3-2-1 Electrochemical data for porphyrinsYD-0-YD-8.................51
Table 3-2-2 Absorption and Fluorescence Data for Porphyrin YD0-YD
………………………………………………………………………..…52
Table 3-2-3 Absorption, fluorescence, and electrochemical data for porphyrin YD-0-YD-8…………………………………………………5
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Natural Propagation and Habitat improvement, Volume 2B, Washington, Similkameen River Habitat Inventory, 1983 Final Report.
No full textDuring the summer low flow period, a habitat assessment of the Similkameen, Tulameen, Ashnola and Pasayten rivers in British Columbia and Washington State was conducted between August 10 and October 10, 1983. The biophysical survey assessed 400 km (250 mi) of stream at 77 stations. Fish sampling was conducted at each station to assess the resident fish populations and standing crop. Rainbow trout populations and standing crops were found to be very low. Large populations of mountain whitefish and bridgelip suckers were present in the manstem Similkameen River below Similkameen Falls. High densities of sculpins and longnose dace were found throughout the system except for sculpins above the falls, where none were captured. Approximately 961,000 m/sup 2/ (1,150,000 yd/sup 2/) of spawnable area for steelhead trout were estimated for the entire system which could accommodate 98,000 spawners. Nearly 367,000 m/sup 2/ (439,000 yd/sup 2/) of chinook salmon spawnable area was also estimated, capable of accommodating 55,000 chinook. Rearing area for steelhead trout smolts was estimated for the whole system at 1.8 million m/sup 2/ (2.2 million yd/sup 2/). Chinook salmon smolt rearing area was estimated at 700,000 m/sup 2/ (837,000 yd/sup 2/). Rearing area was found to be a limiting factor to anadromous production in a Similkameen River system. Smolt production from the system was estimated 610,000 steelhead trout and between 1.6 million and 4.8 million chinook salmon. No water quality, temperature or flow problems for anadromous salmonids were evident from the available data and the habitat inventory. In addition to an impassable falls on the Tulameen River at river mile 32.5, only two other areas of difficult passage exist in the system, Similkameen Falls (a series of chutes) and the steep, narrow lower section of the Ashnola River. 51 references, 18 figures, 25 tables
Dietary supplementation with yeast hydrolysate in pregnancy influences colostrum yield and gut microbiota of sows and piglets after birth.
Get PDFDietary supplementation with yeast derivatives (YD) contributes to the health and physiology of sows and piglets, but few studies have focused on how it influences gut health and performance of sows and piglets. The goal was therefore to examine whether YD, based on brewer's yeast hydrolysate added to pregnancy diet, would affect colostrum composition, yield (CY) and gut microbiota of sows and piglets. Sows were allocated to either a control diet (n = 19) or a control diet supplemented with 2g YD/kg (n = 18) during the pregnancy. Piglets suckling belonging to the control sows (n = 114) and supplemented sows (n = 108) were also included in the study. Gut microbiota populations of sows at farrowing and piglets at one and four weeks of age were assessed using 16S rRNA gene sequencing. Colostrum samples were examined for nutritional composition and immunoglobulin (Ig) content. All piglets were individually weighed at birth and 24 hours later in order to calculate CY, and later at four weeks to calculate average daily gain (ADG). Protein, lactose and dry matter content of colostrum did not significantly differ between the two groups, while sows fed YD had higher levels of fat in their colostrum (P 0.05). Colostrum yield was lower in the control than that in YD group (3701g vs. 4581 g; P <0.05). Although the YD supplementation did not change fecal bacteria diversity in sow, more beneficial and fermentative bacteria (Roseburia, Paraprevotella, Eubacterium) were found in the YD fed group (P <0.01) while, some opportunistic pathogens, including Proteobacteria, especially the genera Desulfovibrio, Escherichia/Shigella and Helicobacter, were suppressed. Piglets at one week of age from sows fed YD had more beneficial microbial populations with significant diversity and fewer opportunistic pathogens. Additionally, we established a Pearson's correlations between CY, colostrum components, piglet birth weight and fecal microbiota. Therefore, YD added to the sow diet during pregnancy increases colostrum availability and its energy content for neonate piglets, also promoting beneficial maternal microbial sources for neonate
Three-Phase Medium-Voltage Medium-Frequency Transformer for SST in Green Hydrogen Production
No full textGreen hydrogen production uses renewable energies to energise the electrolysers for hydrogen production. The present paper compares possible solutions and configurations of a medium-frequency transformer (MFT) as part of a solid-state transformer (SST) in green hydrogen production applications. The single-phase and three-phase MFTs are compared and it is shown that a Yd three-phase MFT is the optimum choice for applications that require high power delivery and step-down of the voltage. A summary of previous works about MFT is also provided. Three-phase SST based on modular multilevel converters (MMC) is then described and various cases are investigated to obtain the optimum operational frequency. A 25 MVA, 400 Hz, 25.4 kV / 560V oil-immersed MFT design is presented and is shown that the proposed 400 Hz transformer saves 69% of the active parts' weight compared to a conventional line-frequency transformer (LFT).Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.High Voltage Technology GroupDC systems, Energy conversion & Storag
Investigation of Vertical Leakage Loss for Whispering-Gallery Modes in Microcylinder Resonators
No full textThe vertical leakage characteristics are investigated for whispering-gallery modes (WGMs) in the microcylinder resonators with vertical semiconductor waveguiding. The mode coupling between HE and EH modes at the boundaries between the core and cladding layers results in a vertical leakage loss for the WGMs, if the transformed modes can propagate in the cladding layer. The core-layer-thickness-dependent vertical leakage loss caused by the internal interference is demonstrated and numerical simulated for the WGMs by the finite-difference time-domain (FDTD) technique. An oscillation of mode factor is found with the increase of the thickness of core layer due to the internal interference between the transmitted and reflected leakage modes, and the vertical leakage loss can be canceled at some thicknesses of the core layer because of the destructive interference. Furthermore, the vertical leakage loss can also be controlled by the external interference in the microcylinder resonator with two vertical coupled core layers. The enhancements of factors for both symmetric and antisymmetric modes are observed by varying the gap between the two core layers
Stalagmite-inferred hydroclimate changes in northern Italy during Allerød/Younger Dryas transition
No full textInternational audienceThe Younger Dryas (YD), a 1200-year-long cooling event interrupting the warm Bølling-Allerød period, started from 12,870 ± 30 yr BP (2σ, before 1950 C.E.). Here we present decadal-resolved stalagmite BA18-2 multi-proxy records from Bàsura cave, northern Italy. The StalAge age-depth model with 8 U-Th dates with 2-sigma errors of ± 26-193 yrs shows that BA18-2 encompasses Allerød/YD transition, from 14,038 ± 92 to 12,090 ± 54 yr BP. Oxygen isotope data fluctuate between-7.16‰ and-3.68‰, with a clear 2.4‰ increase during the YD onset at 12,870 ± 30 yr BP. Stalagmite BA18-2 Sr/Ca and Ba/Ca linger from 0.060-0.085 mmol/mol and 6.4-9.1 µmol/mol, respectively, from 14,038 ± 92 to 12,681 ± 55 yr BP, ~2 centuries after the beginning of YD. A clear 160 year-long two-step increase in both Sr/Ca and Ba/Ca records started from 12,681 ± 55 yr BP, which is a 200-yr lag relative to the timing of BA18-2 oxygen isotope increasing trend. We argue that the oxygen isotope could be governed by moisture source; while, the carbon isotopes, Sr/Ca and Ba/Ca ratios predominantly reflect precipitation change. Our results suggest asynchronous thermal and hydrological changes in northern Italy during the Allerøod/YD transition
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