1,720,964 research outputs found
Design and Synthesis of Amido- and Carbamoyl- anthraquinones as Potential Antitumor Agents
No full text很多抗癌藥物具有很好細胞毒殺效果但卻沒有選擇性，增加抗癌藥物對DNA序列的選擇性可能可以減低毒性以及其他副作用。像 ametantrone 和 mitoxantrone 這類化合物抗癌方面已使用了很久的時間，有平面的蒽醌骨架的mitoxantrone 現在仍是臨床用藥。具有蒽醌類平面骨架的對於DNA的識別及結合是必須的而且在結合上DNA後進一步影響DNA的正常功能，例如轉譯RNA及複製DNA。而且這些嵌入DNA的分子可能可以辨識某些特定的鹼基對。為了改善對DNA親和力以及選擇性，設計以及平行合成蒽醌骨架這一系列化合物。我們保留了 mitoxantrone 具平面特性的三環骨架以及2-(aminoethyl)amino側鏈來接上各種胺基酸。接上的胺基酸側鏈可以對DNA產生離子作用力來加強對DNA的親和力。然而，胜肽骨架並不穩定容易被蛋白酶水解。近來在仿胜肽中很多應用了胺基甲醯基骨架替換醯胺基骨架。我們還原胺基酸並導入了 carbonyloxy 基團，再將 carbonyloxy 單體接到蒽醌骨架上，並且嘗試發展一個簡單的合成方式以便用來進行平行合成一系列具有胺基甲醯基側鏈的蒽醌類化合物。一些新的蒽醌類衍生物在人類癌細胞株上表現有不錯的細胞毒殺效果。Most antitumor agents are highly cytotoxic but not selective. Increasing the lignad selectivity to specific DNA sequences may reduce their toxicity and other adverse effects. Drugs containing 9,10-anthracenedione, such as ametantrone and mitoxantrone, have been used as anti-tumor agents for a long time. Now mitoxantrone, which contains a planar anthraquinone skeleton, is a clinically useful antitumor agent. The planar characteristics of the core structure 9,10-anthracenedione are necessary for molecular recognition and binding into the base pairs of DNA helix to affect transcription and replication processes of the cell . This intercalative interaction may serve as an anchor for intercalating drugs at specific sites of DNA base pair followed by cell-killing. With the aims to increase the DNA affinity and selectivity, a series of l,4-bis[(2-aminoethyl)amino] substituted9,l0-anthracenedione was designed and prepared by parallel synthesis. We reserve the planar characteristics of the core structure 9,10-anthracenedione,and the 2-(aminoethyl)amino of mitoxantrone. The 2-(aminoethyl)amino could be linked a variety of amino acids. The side chain amino acids will create ionic interaction with the ribose phosphates of the nucleic acids. Howevre, the peptide backbone is not stable to proteolytic degradation. Recently an increasing amount of attention has focused on the application of the carbamate moiety as a replacement for the amide bond in peptidomimetics. We reduced the amino acid to amino alcohol and introduced a carbonyloxy group. In order to introduce the carbonyloxy monomer to anthracqueinone skeleton, we are trying to develop a convenient general method for parallel synthesis. Several novel anthracqueinone derivatives showed significant cytotoxicoty against different houmor cancer cell lines.中文摘要 1
英文摘要 2
1 背景與研究目的 3
1-1 背景 3
1-2 研究目的 6
2 結果與討論 7
2-1 化學合成部分 7
2-1-1 蒽醌類化合物中間體合成方法 7
2-2-2 醯胺基蒽醌類化合物合成方法 9
2-2-3 胺基甲醯基蒽醌類化合物合成方法 15
2-2 藥理部分 18
2-2-1 藥理實驗方法 18
2-2-2 藥理實驗結果 19
3 結論 30
4 實驗部分 31
4-1 試劑及溶劑來源 31
4-2 一般儀器與方法 32
4-3 合成步驟 33
5 參考文獻 87
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Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Removal of inorganic N and metformin by simultaneous partial nitrification, anammox and denitrification enhanced by immobilization of anammox
No full textWith the development of the technology and medical industries in the last decades, pollution of nitrogen, as well as pharmaceuticals and personal care products (PPCPs), have been increasingly observed in water environments. Besides the adverse effects such as eutrophication caused by the occurrence of these contaminants, PPCPs are likely to form carcinogenic disinfection byproducts (DBPs) such as nitrosamines during disinfection, causing harm to human health. Anaerobic ammonium oxidation (Anammox) is novel biotechnology with the benefit of chemoautotrophic bacteria. In the process, organic compounds are converted into carbon dioxide with ammonium and nitrite being the electron acceptors and converted into inert N2 in an anaerobic environment. The major advantages of anammox include low sludge production, a small amount of organic carbon supply, limited aeration et al. In recent years, technologies in response to the applications of anammox have emerged one after another. For example, biofilm and bioimmobilization based on attached growth can shorten the start-up time, while partial nitrification, anammox, and denitrification (Simultaneous partial nitrification, anammox, and denitrification, SNAD) using heterotrophic denitrifying bacteria to perform denitrification reaction with organic carbon to overcome the inhibition of the activity of anammox by organic load, which can simultaneously remove inorganic nitrogen and organic carbon to achieve higher nitrogen removal efficiency. The objective of this study was to test the feasibility of using polyethylene glycol (PEG), chitosan (CS), or sodium alginate (SA) as packing or carrier to accelerate the growth of anammox. The approaches included planting in or on the gels made of PEG, CS, and SA, respectively. The feasibility was determined by the observation of the change in the removal efficiencies of inorganic nitrogen. After determining the optimal immobilization method, it was tested to employ anammox to start SNAD, with respect to the observation of inorganic nitrogen removal variations and the assistance of the next-generation biotechnology to judge whether the SNAD was successfully started. Anammox activated by bio-immobilization and SNAD system activated by adding denitrifying bacteria using anammox were also studied for their capability to degrade metformin, the most widely used diabetes drug in Taiwan.
The results showed that, in the result of the bio-embedding material test, when PEG and CS were used as bio-carriers or bio-embedding methods, the reaction efficiency of anammox was poor. When PEG was used for bio-embedding, the removal rates of ammonia nitrogen and nitrite nitrogen were 36% and 20%, respectively. The possible explanation is that the production of PEG packing requires irradiation with UV, which may inhibit the growth of light-sensitive anammox. When CS was used for bio-encapsulation, the removal rates of ammonia nitrogen and nitrite nitrogen were 50% and -15%, respectively. When CS was used as a biological carrier, the removal rate of ammonia nitrogen and nitrite nitrogen were 29% and -28%, respectively. The amine group of CS could compete with anammox for electrons, resulting in the inhibition of the anammox activity. However, in the result of SA, anammox encapsulated by SA was effectively enriched and grown. When SA was used for bio-encapsulation, the removal rate of ammonia nitrogen and nitrite nitrogen were 70% and 76%, respectively, with a start-up time of about 30 days. When SA was used as a biological carrier, The removal rate of ammonia nitrogen and nitrite nitrogen were 73% and 85% respectively, with a start-up time of about 30 days. Overall, SA was successfully used for bio-embedding of anammox, effectively shortening the start-up time. Using denitrifying and anammox bacteria to start the SNAD with SA as a biological carrier, the final removal rates of ammonium, total nitrogen, and COD were 84%, 76%, and 95% respectively, with effective control of dissolved oxygen through intermittent aeration. For the removal of pharmaceutical, metformin, the removal efficiency of using SA for bio-encapsulation was less than 20%. The removal efficiency of using SA as a bio-carrier was 32%. It is speculated that SA used for bio-encapsulation less effectively degraded metformin while using SA as a bio-carrier to degrade metformin was better. However, the removal rate was still rather limited. The removal efficiency of using SNAD for metformin removal was 67.7 %, suggesting that metformin biodegradation in a SNAD system was more efficient compared with those using SA for bio-entrapmentment
Treatment of high-concentration NMP wastewater by light-Fenton enhanced-advanced oxidation process using an etching wastewater from a semiconductor industry
No full textWith the accelerated development of science and technology across the countries, many advanced technologies rely on wafers manufactured by semiconductors. The etching in the manufacturing process is one of the main wastewater sources in the wafer manufacturing process, as the process produces a large amount of etching wastewater and stripping wastewater. Etching wastewater typically contains hydrogen peroxide at high levels, which is corrosive and highly oxidative. The stripping wastewater contains high concentrations of chemical oxygen demand (COD) making it difficult to treat. This study attempts to integrate the treatment of etching wastewater with a high hydrogen peroxide concentration and stripping wastewater with high COD based on the perspective of reuse of wastewater. The feasibility of utilizing strongly oxidative hydrogen peroxide in the titanium etching wastewater from two factories, A ad B, with ultraviolet (UV) light to remove high COD concentration by the presence of N-Methylpyrrolidinone (NMP) in stripping wastewater from factory B was investigated, with respect to the exploration of the effects of different mixing ratios, concentrations of additional catalysts, reaction time et al. The potential of this technology for wastewater from different factories was tested as well.
The results show that mixing the titanium-containing etching wastewater from different factories with the stripping wastewater effectively removed the COD with different efficiencies. The titanium-containing etching wastewater from factory A and the stripping wastewater from factory B were mixed at a volume ratio of 2:1, with the addition of 4 mM TiO2 mixed with Fe(III) and the exposure of 313nm UV for 1 hour, showing that the COD removal effect reached 62.9%. Whereas, the titanium-containing etching wastewater from another factory B and the stripping wastewater from factory B were mixed in a volume ratio of 5:1, with the addition of 2mM TiO2 mixed with Fe(III) and the same exposure of 313nm UV light for 1 hour, showing that the COD removal effect reached 75.6%. The COD removal was significantly affected by whether the amount of oxidant added was sufficient or not, excess catalyst concentration, and long reaction times. It suggests that the future application of the technology may need to frstly predict the concentration of H2O2 in the etching wastewater, the amount of catalyst input, and the reaction time, as these factors may affect the treatment effciency increasing the effluent COD by partially destroying the complex structures of different organic conpounds such as NMP in the stripping wastewater. The optimal pH was the pH when the titanium-containing etching wastewater was mixed with the stripping wastewater with the catalyst added. Although the addition of sodium hydroxide improved the COD removal efficiency, it also reduces the H2O2 concentration, negatively affecting the efficiency of generating hydroxyl or other radicals. The study confirmed that the high COD in the stripping wastewater can be reduced by using the titanium-containing etching wastewater with the help of additional catalysts (TiO2 and Fe(III)). After this treatment, the treated wastewater can be further treated by adding sodium hydroxide (NaOH) to remove the residual H2O2 concentration in the water. The treated wastewater can be introduced into the front end of the existing wastewater treatment processes (such as organic collection tanks), the COD and ammonia nitrogen (NH3) treatment of the existing wastewater treatment processes were limitedly affected, as the final discharged could comply with the associated effluent standards.
The daily treatment cost of the original etching wastewater and stripping wastewater is NT$170,000 per m3 of wastewater. Given the technology proposed in this study and the amount of etching wastewater that can be provided on-site, the treatment cost was reduced by 13.6%. However, with more etching wastewater possibly provided from other factories, the cost was expected to be reduced by 75.0%. With the support from the existing wastewater treatment plant, the original burden due to the treatment of these wastewaters can be alleviated, providing a possible direction for the recycling and reuse of wastewaters in the future
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