磁性流體可調性折射率特性之研究與應用
磁性流體(magnetic fluids)是一種含有磁性奈米粒子的液體,當磁場外加於磁性流體時,流體中各磁性奈米粒子的磁矩會沿外加磁場方向排列,而導致粒子間相互吸引,形成較大的磁性叢集,即所謂的磁鍊。當外加磁場增強,該磁鍊數會變多,並使磁性流體的折射率產生變化。磁性流體的折射率變化會隨外加磁場之變大而增大。本研究除探討磁性流體折射率受外加磁場控制的變化情形及其物理原由外,並進一步運用此特性研發可調性光纖「光調制器」 ,以探討磁性流體可調性折射率應用在光電元件上的可行性。A magnetic fluid is one kind of colloids which contain magnetic nano-particles. Under an external magnetic field, the magnetic moment of nano-particles is aligned along the direction of the external magnetic field. This leads to the agglomeration of magnetic particles and to form magnetic clusters under an external magnetic field. With the formation of the magnetic clusters, the refractive index of magnetic fluid is varied. The refractive index of magnetic fluid was found to increase under a higher magnetic field. In this work, In addition to investigating in detail the behavior of the field-dependent refractive index of the magnetic fluid, we also explore the relevant physical origins. Furthermore, the feasibility of developing fiber-optical modulators by utilizing the tunable refractive index of magnetic fluids is discussed.
氣流式薄膜測厚儀
醫學上的植皮手術成功率受皮膚厚度影響,皮膚愈薄癒合速度愈快,其中以取皮厚度介於0.05mm 到0.1mm 為佳。在實驗量測時,需要經過一連串繁複的薄皮標本製作,再放到光學顯微鏡下測量,這種厚度測量方式不但耗時,又因嚴重損毀皮膚而不精確。由於使用螺旋測微器做接觸式測量會有形變的問題,因此我們想做間接接觸式的測量,所以採用氣體為媒介,做非破壞性檢測膜厚,這對於在皮膚上的施力遠小於螺旋測微器或是接觸式膜厚計。我們設計一套三頭連管線,使用空氣為媒介,儀器運作原理為在管線一端針頭非常靠近被測物時,所流出的氣體會受到被測物阻礙產生反壓使管線內的壓力上升,導致連通於另一管路的氣泡指示計壓出氣泡,當氣泡為最大氣泡時(半球形)視為達到平衡狀態。實驗時先用已知厚度且不變形的蓋玻片來當作被測物,此時可以算出針尖至蓋玻片的實際距離做為參考值。在量測軟性薄膜時,設計上採用兩側雙針頭靠近軟性被測薄膜兩側以達到氣流氣泡平衡,這時使用螺旋測微器讀取兩針尖距離,減去已知參考值的兩倍距離,即可測出未形變的軟物質厚度。本研究開發一套能測量軟性薄膜的厚度裝置,尤其在皮膚厚度測定上,不但不會直接接觸標本造成損毀,並且能夠快速地測量出厚度值,此為本儀器的最大特色。The thickness of skin graft has deterministic influences on the success of graft surgery. Experimental measurements of skin graft thickness involve complicated specimen preparation processes followed by optical microscopic examination, which are time-consuming and may incur inaccuracy due to possible damage. Here we propose a novel method using air as the media to avoid direct contact of the measured object. The physical operation relies on the following principles: When the tip of a needle connecting to a catheter system is placed close to the object to be measured, the air pumped forward from the catheter system becomes impeded by the object. The resulting backflow pressure opposing the air flow causes an increase in air pressure within the catheter and inflates the bubble connected at the other end. Balance at maximal surface tension is attained when the bubble reaches its maximum volume in hemispherical shape. In practice, a two-needle design was used, each approaching simultaneously from each side of the object. A micrometer was then used to read the distance between the two needle tips, from which the film thickness was derived, subtracting the thickness of the air layer pre-calibrated using cover glass with known thickness. The system implemented was capable of measuring thickness on soft thin films with an accuracy of ± 0.001mm. In addition to rapid measurements with high accuracy, since the pressure exerted on the skin graft is much less than in conventional calipers requiring direct contact, our method has the unique non-distorted and non-destructive advantages.
Discovery of new bioactivities of violacein and its erivatives synthesized by Chromobacterium sp.
目的:紫色桿菌(Chromobacterium sp.)是一種生活在土壤及水域環境的革蘭氏陰性菌,它會產生紫黑色的紫色桿菌素(Violacein),因而使菌體與培養液皆呈紫色。Violacein是一種由兩個L-色胺酸(L-tryptophan)分子所聚合成的五環化合物,已被證實具有抗菌以及抑制腫瘤細胞生長的活性。本實驗的目的在探討紫色桿菌是否會利用不同官能基的L-色胺酸,合成不同的Violacein衍生物,並分析這些Violacein衍生物的生物活性。方法:將紫色桿菌培養於液態LB培養基中,分別加入不同濃度的L-tryptophan、1-CH3-L-tryptophan與5-OH-L-tryptophan,於室溫下培養48小時,再用乙酸乙酯萃取Violacein及其衍生物,將萃取出來的紫色桿菌素,用紫外光/可見光分光光譜計和質譜儀進行分析。最後,再將這些萃取物打入斑馬魚受精卵做胚胎毒性測試,並進行試管外DNA剪切能力分析。結果:加入不同官能基的L-色胺酸所合成的產物都是紫色,且在紫外光/可見光的光譜中的最大吸收波長皆相同,質譜儀分析結果則顯示,L-tryptophan 、與5-OH-L-tryptophan的產物圖譜不同、而1-CH3-L-tryptophan的產物則無法分析。斑馬魚胚胎毒性測試結果顯示,Violaecein和1-CH3-Violacein 不會對胚胎發育造成影響,但是5-OH-Violacein則會造成胚胎發育異常。DNA 剪切能力測試也顯示,只有5-OH-Violacein具有剪切DNA的能力,其他則否。重要性:本實驗成功地利用紫色桿菌合成Violacein及其衍生物,並發現了5-OH-Violacein比Violacein 具有更高的生物活性。;Aims: Chromobacterium sp. is a Gram negative bacterium which inhabit in soil and water environments. Chromobacterium produce a purple color compound named Violacein. This colorful compound makes Chromobacterium and its culture mediumin purple color. Violacein is a five rings compound synthesized from two L-tryptophan molecules. Studies have shown that Violacein has anti-bacteria and anti-tumor activities. The purpose of this study is to investigate whether Violacein can be synthesized from different tryptophan analogues, and whether these Violacein derivatives have different bioactivities. Materials and Methods: Chromobacterium sp. was cultured in liquid medium containing different concentrations of L-tryptophan, 1-CH3-L-tryptophan, and 5-OH-L-tryptophan. After 48 hours incubation at room temperature, Violacein and its derivatives were extracted by EA, analyzed by UV/visible spectrophotometer and MS. Violacein and its derivatives were also tested for their embryo toxicity and DNA cleavage activity in vitro. Results: The compounds synthesized from different tryptophan analogues were all purple and have the same maxima absorption wave length in the UV/visible spectra. However, MS spectra of compounds synthesized from L-tryptophan and 5-OH-L-tryptophan were different. The results of zebrafish embryo toxicity tests indicated that violaecin and 1-CH3-Violacein had no effect on embryo development, but 5-OH-Violacein caused development defects. DNA cleavage tests also showed that only 5-OH-Violacein could digest DNA in vitro. Violaecin and 1-CH3-Violacein could not digest DNA. Significances: Results from this study indicate that Chromobacterium sp. can be used to synthesize Violacein derivatives from different tryptophan analogues, and revealed that 5-OH-Violacein is a higher bioactivity compound than violaecein.
蟋蟀的聲音分析與聲音行為探討
蟋蟀聲音與行為的關係密不可分。取北部四種蟋蟀樣本,以數位錄音筆錄製及電腦軟體分析蟋蟀的聲音,並用PCR技術萃取蟋蟀的粒線體DNA(16S)加以分析,藉此和傳統的形態學分類相互比較。結果發現蟋蟀聲音的頻率特性中主頻率的差異在親緣遠近有關聯性,但聲音的時間特性方面則沒有特定關聯,不過聲學分析圖仍可作為單一種的鑑定指標。此外,研究發現此4種蟋蟀的聲音頻率範圍有重疊現象,但主頻率、脈衝比、唧聲率及唧聲長不同,推測雌蟋蟀應是綜合這些特性辨別同種。另一方面,以黑蟋蟀作為研究對象,進行干擾實驗,觀察並繪製出其聲音行為模式; 並將此作為對照,結果發現蟋蟀的生殖行為主要受到雄蟋蟀的聲音支配,而雄蟋蟀則以嗅覺辨別雌蟋蟀位置,決定下一步行動,與視覺較無關係。 Cricket's voice is closely related to the behavior. We select four species of crickets from the northern Taiwan to study the acoustic and mating behaviors. The digital sound recorder and acoustic software are used to analyze their acoustic characters. Furthermore, the PCR technology is used to amplify and sequence parts of mtDNA sequences and the results were compiled as the comparison to the traditional morphological character. The result shows that the resolution in acoustic characters of main frequency, pulse number, chirp rate, and the length of chirp are different among four species, though the minor frequency pattern is overlapping. Moreover, we find that frequency characteristic difference among four species is partly related to their phylogenetic relationship, yet is not seen in time characteristic. It is obvious that difference of acoustic behavior can be regarded as identified index among species. Results of acoustic analysis impel us to infer that the female crickets take the comprehensive acoustic behavior to distinguish their specific male. In addition, behavior pattern and model of Gryllus bimaculatus are established as the comparison of interfering experiment is undertaken. Which results suggest that the mating behavior in cricket is dominated by males’ acoustic behavior, and is initiated by male’s olfactory sense rather than that of sight.