Fundamental elements of chrome-collagen interactions and the crosslinking mechanism at the molecular level have been investigated to gain detailed understanding that can be translated into improvements in the commercial process. Amide group hydrolysis during conventional liming proceeds by two mechanisms: direct hydrolysis with hydroxyl catalysis or intramolecular catalysed hydrolysis that can be measured by the degree of racemisation at L- asparagine. Gas chromatography mass spectrometry analysis of limed collagen demonstrated that there was no initial rise in the amount of D-aspartic acid during the first 24 hours of liming, indicating that, within the conventional period of liming, collagen remained intact. Circular dichroism has demonstrated that beamhouse processing has dispersive and relaxing effects on the collagen triple helices, but without disruption. Attenuated total reflection Fourier transform infrared spectroscopy analysis provided information regarding changes in the secondary structure of collagen during tanning. Complete breakdown of chrome tanned collagen was achieved by the use of a cocktail of proteolytic enzymes: this allowed an analysis of the isolated crosslinks, which indicated preferred reaction at aspartate sidechain carboxyls. This is supported by chrome tanning studies following treatment of collagen by amidase enzymes. Geometric details of chromium(lll) species involved in the tanning reaction were elucidated by extended X-ray absorption fine structure analysis. Linear tetrameric chromium species were found to be predominant in the tanning process. Direct measurements of the mechanism were made using electron spin resonance spectroscopy. A two-stage reaction mechanism is postulated: physical interaction and chemical complexation, affected by reaction conditions such as pH, temperature and the presence of neutral salts. Nuclear magnetic relaxation dispersion measurements confirmed changes in the speciation of chromium(lll) under tanning conditions.

Vegetable tannins used in tanning of hides and skins are limited to surface reactions by their large molecular weights. The molecular weight reduces penetration into the skin and lowers the thermal stability or tanning effect. Investigation into the utilisation of small phenolic compounds such as catechin to improve penetration with subsequent in situ enzymecatalysed polymerisation may provide a novel and alternative tanning agent. In this research, catechin was oxidised by enzymatic catalysis using laccase, with the polymerisation confirmed by FT-IR and UHPLC. Tanning experiments were undertaken to measure the effect of laccase-catalysed polymerisation of catechin in the thermal stabilisation of collagen, by monitoring the change in shrinkage temperature between the treated and untreated sample of hide powder (ΔTs). This study demonstrates that the stabilisation of collagen (ΔTs) is increased with the use of in situ enzyme-catalysed polymerisation. Depolymerisation of condensed tannins is presented as an alternative source of low molecular weight phenolics to be applied in the stabilisation of collagen. In this research, mimosa tannin from the Black Wattle tree (Acacia mearnsii) was used in the depolymerisation process. Preliminary experiments on depolymerisation were undertaken using the methods laccase-mediator system and L-cysteine in mild acidic medium, both showing unsatisfactory results. Acid-catalysed depolymerisation followed by nucleophile addition is a common analytical method for determining the degree of polymerisation of proanthocyanidins. The acid-catalysed depolymerisation method was scaled-up, with the addition of pyrogallol as a nucleophile trapping agent, and powdered depolymerised mimosa was obtained. Data show an increase in the monomeric content and decrease in percentage of condensed tannins for the acid-catalysed process, indicating the potential of the depolymerisation of mimosa tannin in obtaining environmentally friendly sources of low molecular weight phenolic compounds for use in large scale/industrial applications. The depolymerised product was applied in the stabilisation of hide powder and goat skin. Using hide powder, data show that the laccase-assisted polymerisation of the depolymerised mimosa reached higher values of ΔTs in comparison with the conventional process employing unmodified mimosa. Using goat skin, the new process achieved similar values of ΔTs as the conventional process. In order to obtain similar results for goat skin as obtained with hide powder, an optimisation may be carried out. Therefore, data obtained demonstrates the potential of the new route in vegetable tanning of leather.

by J. Francis Reintjes. / "July 15, 1976." / Made possible through a grant from the American Newspaper Publishers Association (ANPA).

陳頌文. / "2002年8月". / 論文 (哲學碩士)--香港中文大學, 2002. / 參考文獻 (leaves 127-133) / 附中英文摘要. / "2002 nian 8 yue". / Chen Songwen. / Lun wen (zhe xue shuo shi)--Xianggang Zhong wen da xue, 2002. / Can kao wen xian (leaves 127-133) / Fu Zhong Ying wen zhai yao. / Chapter 第一章 --- 文學史和文學批評史上的初唐四傑 --- p.1 / Chapter 第一節 --- 問題的提出 --- p.1 / Chapter 第二節 --- 「四傑」名稱的由來 --- p.2 / Chapter 第三節 --- 文學史上的「四傑」 --- p.7 / Chapter 第四節 --- 文學批評史上的「四傑」 --- p.8 / Chapter 第二章 --- 貞觀至武周文學背景和文學思想發展 --- p.11 / Chapter 第一節 --- 緒論 --- p.11 / Chapter 第二節 --- 貞觀年間朝廷的文學宣言 --- p.12 / Chapter (1) --- 貞觀年間君臣論文的性質 --- p.12 / Chapter (2) --- 貞觀年間朝廷的文學思想´ؤ´ؤ以史家文論爲主 --- p.15 / Chapter (2.1) --- 史家對六朝文學的評價與總結 --- p.15 / Chapter (2.2) --- 史家論文的空間 --- p.17 / Chapter (2.3) --- 史家文論的意義 --- p.19 / Chapter 第三節 --- 貞觀至武周的文學硏究槪況 --- p.21 / Chapter (1) --- 類書和總集 --- p.21 / Chapter (2) --- 《文選》硏究 --- p.24 / Chapter (3) --- 詩學硏究 --- p.25 / Chapter (3.1) --- 上官儀 --- p.25 / Chapter (3.2) --- 元兢 --- p.27 / Chapter (3.3) --- 崔融 --- p.28 / Chapter 第四節 --- 貞觀至武周文人干求與入仕情況 --- p.29 / Chapter (1) --- 以文章進身的問題 --- p.30 / Chapter (2) --- 以文章進用的大臣仕途之升降 --- p.32 / Chapter (3) --- 王府的文學風氣 --- p.34 / Chapter 第三章 --- 王勃文學思想析論 --- p.35 / Chapter 第一節 --- 緒論´ؤ´ؤ王勃生平及著作槪述 --- p.35 / Chapter 第二節 --- 可供考察文學思想的篇章背景分析 --- p.36 / Chapter (1) --- 〈平臺秘略論 〉、〈平臺秘略贊〉：王府修撰的意見 --- p.36 / Chapter (2) --- 〈上吏部裴侍郎啓〉：參選士子的意見 --- p.37 / Chapter (3) --- 詩賦序文之言論：翰墨之客的意見 --- p.39 / Chapter 第三節 --- 文論文本分析 --- p.40 / Chapter (1) --- 文學的性質與功用 --- p.40 / Chapter (1.1) --- 「甄明大義，矯正末流」、「緣情體物」與「詩以見志」 --- p.40 / Chapter (1.2) --- 文學與王府 --- p.43 / Chapter (1.3) --- 文學與自然 --- p.44 / Chapter (2) --- 對文學作品的要求及規範 --- p.45 / Chapter (2.1) --- 「氣陵雲漢，字挾風霜」辨 --- p.45 / Chapter (2.2) --- 「甄明大義，矯正末流」辨 --- p.48 / Chapter (3) --- 對歷代文學的評價 --- p.53 / Chapter (4) --- 寫作態度 --- p.56 / Chapter (5) --- 小結 --- p.59 / Chapter 第四節 --- 王通與王勃 --- p.60 / Chapter 第四章 --- 楊炯文學思想析論 --- p.64 / Chapter 第一節 --- 緒論´ؤ´ؤ楊炯生平及著作槪述 --- p.64 / Chapter 第二節 --- 〈王勃集序〉析論 --- p.64 / Chapter (1) --- 〈王勃集序〉的寫作時間 --- p.65 / Chapter (2) --- 〈王勃集序〉的內容分析 --- p.68 / Chapter (2.1) --- 〈王勃集序〉與王勃文學變革 --- p.69 / Chapter (2.1.1) --- 從「龍朔變體」看王勃文學變革的對象 --- p.69 / Chapter (2.1.2) --- 從王勃之志看王勃文學變革的可能性 --- p.72 / Chapter (2.1.3) --- 〈王勃集序〉對王勃硏究的參考價値 --- p.75 / Chapter (2.1.4) --- 小結 --- p.76 / Chapter 第三節 --- 楊炯的文學思想 --- p.76 / Chapter (1) --- 文學的性質及作用 --- p.76 / Chapter (1.1) --- 文學與禮樂 --- p.76 / Chapter (1.2) --- 文學與抒情酬唱 --- p.77 / Chapter (2) --- 對文學的要求與規範 --- p.77 / Chapter (3) --- 對歷代文學的批評 --- p.79 / Chapter (3.1) --- 唐以前的文學 --- p.79 / Chapter (3.2) --- 隋唐以來的文學 --- p.80 / Chapter (4) --- 小結 --- p.82 / Chapter 第五章 --- 盧照鄰文學思想析論 --- p.83 / Chapter 第一節 --- 緒論´ؤ´ؤ盧照鄰生平及著作槪述 --- p.83 / Chapter 第二節 --- 可供考察文學思想的篇章背景分析 --- p.84 / Chapter (1) --- 〈駙馬都尉喬君集序〉 --- p.84 / Chapter (2) --- 〈南陽公集序〉 --- p.84 / Chapter (3) --- 〈樂府詩集序〉 --- p.86 / Chapter 第三節 --- 文本分析 --- p.88 / Chapter (1) --- 文學的性質與功用 --- p.88 / Chapter (1.1) --- 文學與政治 --- p.88 / Chapter (1.2) --- 「安可默而無述」 --- p.89 / Chapter (2) --- 對文學作品的要求和規範 --- p.90 / Chapter (2.1) --- 「立體不拘於一塗」 --- p.90 / Chapter (2.2) --- 「聽歌曲而知亡」 --- p.93 / Chapter (2.3) --- 「妙諧鐘律」 --- p.94 / Chapter (3) --- 對歷代文學的評價 --- p.96 / Chapter (3.1) --- 對唐以前文學的評價和態度 --- p.96 / Chapter (3.1.1) --- 〈雅〉、〈頌〉 --- p.96 / Chapter (3.1.2) --- 屈宋 --- p.97 / Chapter (3.1.3) --- 兩漢 --- p.99 / Chapter (3.1.4) --- 魏晉 --- p.99 / Chapter (3.1.5) --- 南朝 --- p.100 / Chapter (3.2) --- 對貞觀文臣的批評 --- p.101 / Chapter (3.3) --- 對古今文士評論文學的意見 --- p.102 / Chapter (4) --- 創作態度 --- p.102 / Chapter (5) --- 小結 --- p.104 / Chapter 第六章 --- 駱賓王文學思想析論 --- p.105 / Chapter 第一節 --- 緒論´ؤ´ؤ駱賓王生平及著作槪述 --- p.105 / Chapter 第二節 --- 可供考察文學思想的篇章背景分析 --- p.106 / Chapter (1) --- 上長官書信 --- p.106 / Chapter (1.1) --- 〈和道王閨情詩啓〉 --- p.106 / Chapter (1.2) --- 〈上吏部裴侍郎書〉、〈上吏部侍郎帝京篇序〉 --- p.106 / Chapter (1.3) --- 〈與程將軍書〉 --- p.107 / Chapter (2) --- 飲宴酬唱之作 --- p.108 / Chapter (3) --- 個人抒懷之作 --- p.108 / Chapter 第三節 --- 文論內容分析 --- p.109 / Chapter (1) --- 文學的性質及功用 --- p.109 / Chapter (1.1) --- 事、物、情與文 --- p.109 / Chapter (1.2) --- 文學與求仕 --- p.111 / Chapter (2) --- 對文學的要求及規範：雅與俗的取捨問題 --- p.113 / Chapter (3) --- 對歷代文學的評價 --- p.115 / Chapter (3.1) --- 兩漢以前 --- p.115 / Chapter (3.2) --- 兩漢 --- p.117 / Chapter (3.3) --- 魏晉 --- p.117 / Chapter (3.4) --- 南朝 --- p.118 / Chapter (4) --- 小結 --- p.118 / Chapter 第七章 --- 總結 --- p.120 / 參考書目 --- p.127 / 附錄一 --- p.132