6,471 research outputs found
Expression patterns of transforming growth factor-beta and its receptors in the gastric mucosa of patients with refractory gastric ulcer.
No full textEvaluation of the Effectiveness of Various Organic Materials on Decreasing Cr(VI) Availability of Cr(VI)-Contaminated Soils
No full text鉻在土壤中以三價陽離子或六價陰離子的型態存在，而六價鉻在土壤中的毒性、移動性及溶解度都遠高於三價鉻。前人研究發現土壤中的有機質能將六價鉻還原成三價鉻，進而降低六價鉻在土壤中的毒性，然而添加不同有機資材於土壤中時，會因其本身之理化性質不同，使其分解速率不同進而影響六價鉻之還原效果。因此本研究之目的為探討添加不同有機資材處理 (大豆粕、牛糞堆肥、蔗渣堆肥及米糠) 對土壤中六價鉻之有效性之影響。
本試驗選定三種台灣代表性土系 (平鎮系(Pc)、將軍系（Cf）、太康系（Tk）) 作為供試土壤。將三種供試土壤分別添加K2Cr2O7溶液使其含有 0 及 500 mg Cr(VI) kg-1，加水至飽和狀態，進行三次乾濕交替。之後分別添加蔗渣堆肥 (SCDC)、牛糞堆肥(CC)、大豆粕 (SBM)及米糠 (RB)等四種有機資材於三種供試土壤中，使每公斤供試土壤增加 0、1 % 及 2 % 的有機質，於 25 ℃，田間容水量下孵育 40 天。各處理分別於孵育之第 0、4、8、12、20、30、40 天取出部份土樣，經風乾研磨過80 mesh的篩網之後，利用DOWEX M4195選擇性離子交換樹脂抽出土壤中有效性之六價鉻。另外取出孵育第 21 天之土壤，經風乾研磨過230 mesh的篩網後，進行X光吸收近邊緣結構光譜(XANES)測定。
由 DOWEX M4195 選擇性離子交換樹脂抽出結果發現，平鎮系土壤在不添加有機資材孵育下即能使土壤中有效性六價鉻降低至 10 mg kg-1。而在太康系與將軍系土壤中添加四種有機資材處理之後，土壤中之有效性六價鉻皆明顯下降，其中以添加大豆粕與米糠的效果最為快速。添加六價鉻之太康系與將軍系的土壤經三次乾濕交替後樹脂抽出有效性六價鉻分別為 149.8 及 160.7 mg kg-1，在添加 1 % 的大豆粕與米糠孵育 8 天後，能使有效性六價鉻降低至10 mg kg-1以下，而添加 2 % 的大豆粕與米糠孵育4天後即能達相同之效果。將添加不同有機資材孵育不同天數後之土壤樹脂可抽出六價鉻含量利用一級動力方程式進行套配，求得太康系土壤中六價鉻之還原速率係數分別為蔗渣堆肥 0.052 day-1、牛糞堆肥 0.18 day-1、米糠0.47 day-1及大豆粕 0.5 day-1，在將軍系土壤中六價鉻之還原速率係數分別為蔗渣堆肥 0.09 day-1、牛糞堆肥 0.174 day-1、米糠 0.44 day-1 及大豆粕 0.28 day-1。由有機資材之基本性質可知有機資材在土壤中之分解難易程度，大豆粕與米糠都是屬於較易分解之有機資材，而在土壤中大豆粕又比米糠更容易分解，但是我們從試驗結果中發現添加米糠孵育後六價鉻之還原速率大於大豆粕，可能的原因是米糠 C/N 比高於大豆粕且米糠中之有機碳比大豆粕多，因此能提供更多電子使六價鉻還原更快速。
XANES 測定結果我們發現，三種添加六價鉻但未添加有機資材土壤之譜圖於 5992-5994 eV 的位置皆有明顯之 pre-edge，表示在土壤中有六價鉻存在。而添加有機資材孵育後，pre-edge 有下降的趨勢，表示有機資材能將土壤中之六價鉻還原成三價鉻。
利用有機資材添加還原污染土壤中之六價鉻是常被使用的一種整治方法。綜合本研究結果，建議在有機資材的挑選上，首先要考慮能在土壤中快速分解之資材，並且也要有適當之 C/N 比，如此才能更快速的還原土壤中之有效性六價鉻。Chromium is present in soils in Cr(III) cation or Cr(VI) oxyanion forms. Cr(VI) is more toxic and mobile than Cr(III). Adding organic materials into soil can reduce Cr(VI) to Cr(III) which in turn reduces the toxicity of Cr(VI). The reduction effectiveness of Cr(VI) is influenced by the rate of decomposition of added organic materials. The characteristics of organic materials will vary in how they affect their rate of decomposition. The purpose of this study is to evaluate the effectiveness of various organic materials on decreasing Cr(VI) availability of Cr(VI)-contaminated soils.
Three representative soils of Taiwan [Pinchung (Pc), Chingchung (Cf), and Taikang (Tk)] were used in this study. These soils were added with K2Cr2O7 solution to reach the level of 0 and 500 mg Cr(VI) kg-1 respectively and gone through 3 drying and wetting cycles to prepare Cr(VI)-spiked soil. Organic matter was added into Cr(VI)-spiked soils with 0, 1 % and 2 % by dry weight in the form of sugarcane dregs compost (SCDC), cattle-dung compost, soybean meal (SBM) and rice bran (RB). The organic materials amended soils were then incubated in field capacity at 20 ℃. Soils were taken out after 0, 4, 8, 12, 20, 30 and 40 day of incubation. For extracting soil available Cr(VI) the DOWEX M4195 selective ion exchange resin was used. The degree of soil Cr(VI) reduction to Cr(III) after incubation 21 days was identified by X-ray adsorption near edge structure spectroscopy (XANES).
Results from this study indicate that only 10 mg Cr(VI) kg-1 were extracted in Pc Cr(VI)-spiked soil (500 mg Cr(VI) kg-1 ) without adding organic materials after 40 days of incubation.Most of the Cr(VI) was reduced by the natyral organic matter of Pc soils.. The addition of organic materials into Cf and Tk soils significantly decreased the amount of extractable Cr(VI). Among the four organic materials, SBM and RB were the most effective ones in reducing Cr(VI). Less than 10 mg Cr(VI) kg-1 were extracted from Cr(VI)-spiked soil amended with 1 % organic matter in the form of SBM and RB after 8 days of incubation and with 2 % organic matter in the form of SBM and RB after 4 days of incubation. The relationship between the soil extractable Cr(VI) and the incubation time was described by the first-order kinetic equation, and the rate coefficients of Cr(VI) for adding SCDC, CC, RB and SBM were 0.052 day-1, 0.18 day-1, 0.47 day-1 and 0.5 day-1 in TK soil, and 0.09day-1, 0.174 day-1, 0.44 day-1 and0.28 day-1 in Cf soil respectively. The different rate coefficients are due to the different rates of decomposition of the organic materials in soils. Although both the SBM and RB were easily decomposed in soil, the higher C/N ratio of the RB resulted in the higher effectiveness of Cr(VI) reduction than SBM.
Comparing the XANES spectra of Cr(VI)-spiked soils with and without organic material amendments for Cf and Tk-soils, it is evident that the intensity of the Cr(VI) peak was significantly lower with organic materials amendments. The XANES results suggested that the reduction of Cr(VI) to Cr(III) was the dominant mechanism for the decrease of soil available Cr(VI) when organic materials were added.
The above results suggest that when adding organic materials into Cr(VI)- contaminated soil to reduce Cr(VI), the materials that can be decomposed easily in soil must be chosen. Other than the rate of the decomposition of organic materials, the C/N ratio of organic material is also an important factor that must be taken into consideration.目 錄
摘要（中文）…………………………………………………………………… I
摘要（英文）…………………………………………………………………… III
目錄 …………………………………………………………………………… VI
表次 ………………………………………………………………………… VIII
圖次 …………………………………………………………………………… IX
一 緒論 …………………………………………………………………… 1
1.1 前言 …………………………………………………………………… 1
1.2 環境中的鉻 …………………………………………………………… 1
1.3 鉻污染土壤之復育 …………………………………………………… 5
1.4 研究動機 ……………………………………………………………… 6
1.5 以選擇性離子抽出法交換樹脂評估植物有效性六價鉻 …………… 6
二 材料與方法 …………………………………………………………… 8
2.1 選擇性離子交換樹脂之前處理 ……………………………………… 8
2.1.1選擇性離子交換樹脂之前處理 ………………………………… 8
2.1.2樹脂袋製作流程 ………………………………………………… 10
2.2 供試土壤與有機資材 ………………………………………………… 12
2.2.1 土壤採集與基本性質分析 ……………………………………… 12
2.2.2 有機資材選定與基本性質分析 ………………………………… 14
2.3 六價鉻污染土壤之製備 ……………………………………………… 17
2.4 六價鉻污染土壤添加有機資材孵育處理 …………………………… 17
2.5 以選擇性交換樹脂抽出法評估添加不同有機資材處理降低土壤有效
性Cr(VI) 之效果……………………………………………………… 18
2. 6 X光吸收近邊緣結構光譜 (XANES)之測定 ………………………… 19
2.7 統計分析 ……………………………………………………………… 19
三 結果與討論 …………………………………………………………… 21
3.1 供試土壤及供試有機資材之基本性質 ……………………………… 21
3.2 未添加有機資材土壤中樹脂抽出六價鉻之變化 …………………… 24
3.3 添加不同有機資材孵育後土壤中樹脂抽出六價鉻之變化 ………… 27
3.4 添加不同有機資材對土壤中樹脂抽出有效性六價鉻還原速率之影響 32
3.5 X光吸收近邊緣結構光譜（XANES）分析結果 …………………… 41
四 結論 …………………………………………………………………… 45
五 參考文獻 …………………………………………………………………… 46
六 附錄 ………………………………………………………………………… 5
Visible-light response Cr-doped TiO2-XNX photocatalysts
No full textChromium (Cr) and nitrogen (N)-doped titania (TiO2) was prepared using sol–gel method and ammonia thermal treatment. TiO2 co-doped
with Cr and N showed intense absorption bands in the visible-light region. The X-ray photoelectron spectroscopy (XPS) detected chromium
and nitrogen ions on the surface of catalysts, but no diffractive peak of chromium oxide or titanium nitride was observed in X-ray diffraction
(XRD) spectra. The analysis of X-ray absorption near edge spectroscopy (XANES) indicated either Cr3+ or Cr4+ chemical status implying that
chromium either substituted Ti4+ site or locally was isolated on the surface of TiO2. The photocatalytic activity was evaluated by the degradation
of methylene blue (MB) and isopropyl alcohol (IPA) under visible-light (>460 nm) irradiation using blue-light emitted diode. The rate constants
of MB and IPA photodegradation with N-doped TiO2 were 7.7 and 80 mol l−1 h−1 g−1, which were much higher than those with pure TiO2, 0.15
and 0 mol l−1 h−1 g−1, respectively. The Cr and N co-doped TiO2 showed less photoactivity than either Cr or N-doped TiO2 due to the extra
imperfection of TiO2 lattice during preparation
L'électrocardiographie haute résolution : mise au point et évaluation de l'effet pro-arythmique du flécaïnide chez le chien
Full text linkL'utilisation de l'électrocardiographie haute-résolution en toxicologie est envisagée avec la mise au point d'une technique de recueil sur le chien beagle. Les coefficients de variation intra et inter-jours des quatre paramètres enregistrés (QRSf, LAS40, RMS40, RMS) sont ensuite calculés. Nos résultats montrent que QRSf est plus répétable (1.1%) et reproductible (4.4%) que les autres paramètres et en particulier que LAS40 (respectivement 6.3 et 18.5%). Ces valeurs doivent être prises en compte dans l'interprétation des mesures obtenues lors d'examens successifs, car elles représentent la part de différence attribuable à la méthode et non au produit testé. Les effets du flécaïnide sont ainsi mis ici en évidence par l'allongement de QRSf et LAS40 (+54.9 et +174.6%, p<0.01) et la diminution de RMS40 et RMS (-83 et -65.1% p<0.01). Ils montrent la présence de potentiels ventriculaires tardifs, témoins des retards de conduction cardiaque produits par cet agent antiarythmique
Cr(VI) and Cr(III)-Based Conversion Coatings on Zinc
No full textWith the aims of understanding the protective mechanism of chromate conversion coatings and developing alternatives to chromate treatments, the physical natures and corrosion properties of Cr(VI) and Cr(III) treated zinc have been investigated in this work. The Cr(VI) treatments were carried out in dichromate and sulfuric acid solution with different dipping times. The Cr(III) treatments were carried out in two commercial solutions (A and B). The thickness of the coatings was measured using ellipsometry. The morphologies and the compositions of the treated zinc have been studied by means of SEM, AFM, AES, FTIR and XPS. The drying temperature influence on the corrosion performance of the Cr(VI)âtreated zinc has been investigated. The Volta potential in treated and untreated areas has been measured using scanning Kelvin probe (SKP) and SKPFM. The corrosion behavior of the Cr(VI) and Cr(III) treated zinc has been investigated using polarization, electrochemical impedance measurements (EIS), and salt spray tests. Both Cr(VI) and Cr(III) species were detected by XPS in the outermost layer of the Cr(VI) coatings, while no Cr(VI) species was found in the Cr(III) coatings. AES depth profile results show that chromium oxides are the main components in the Cr(VI) coatings. Zinc oxide is mainly located at the chromium oxides / zinc interface. The Cr(III) coating is a mixture of chromium oxides and zinc oxide. Both the Cr(VI) and the Cr(III) treatments can supply corrosion protection to zinc. The corrosion resistance of the Cr(III)-B coating is greater than that of the Cr(III)-A coating. However, the inhibition of the corrosion of zinc by Cr(VI) coating is more effective than by the Cr(III) coatings. The inhibition of the corrosion of zinc by the Cr(VI) and the Cr(III) treatments is discussed, and future research topics are suggested.Mechanical, Maritime and Materials Engineerin
Quality of Care for Lung Cancer in Taiwan: A Pattern of Care Based on Core Meassures in the Taiwan Cancer database registry.
No full textAn investigation into the numerical prediction of boundary layer transition using the K.Y. Chien turbulence model
Full text linkAssessments were made of the simulation capabilities of transition models developed at the University of Minnesota, as applied to the Launder-Sharma and Lam-Bremhorst two-equation turbulence models, and at The University of Texas at Austin, as applied to the K. Y. Chien two-equation turbulence model. A major shortcoming in the use of the basic K. Y. Chien turbulence model for low-Reynolds number flows was identified. The problem with the Chien model involved premature start of natural transition and a damped response as the simulation moved to fully turbulent flow at the end of transition. This is in contrast to the other two-equation turbulence models at comparable freestream turbulence conditions. The damping of the transition response of the Chien turbulence model leads to an inaccurate estimate of the start and end of transition for freestream turbulence levels greater than 1.0 percent and to difficulty in calculating proper model constants for the transition model
Site occupation in the Cr-Ru and Cr-Os ? phases
No full textThe site occupation in the Cr-Ru and Cr-Os ? phases is computed as a function of temperature. Generally, in ? phases the larger atoms occupy the sites with larger coordinations numbers, as can be explained on the basis of atomic-size and electronic structure. However, for Cr2Ru and Cr2Os the atomic-size argument predicts that Ru and Os occupy the sites with larger coordination numbers, whereas the reasoning based on the approximate degeneracies of electronic levels predicts that Cr occupies those sites. By comparing these predictions with the theoretically computed and the experimentally measured site occupations, the atomic-size and electronic arguments can be judged on their predictive merits.Materials Science and EngineeringMechanical, Maritime and Materials Engineerin
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