終端速度
液體中之球體運動與液體的黏滯性有關,本實驗找出球體半徑與終端速度之間的關係。利用攝錄機作為紀錄工具,拍攝三種材質(壓克力、玻璃、水晶)的球體在沙拉油中的自由落體過程。使用電腦影像處理軟體將影像分解成幅影像,時間的解析度為1/30秒。測量球體的高度與時間,分析高度與時間的變化情形,發現終端速度與球體半徑之間的關係。
流體中之運動方程Fdrag = -k1V,無法符合實驗結果。我們的實驗結果顯示油中的自由落體的運動方程應該是Fdrag = -(k1V+ k2V2)。由不同材質的壓克力球(~1.18g/cm3)、玻璃珠(~2.47g/cm3)與水晶球(~2.66g/cm3)所獲得的終端速度(Vt)與球體半徑(a)的關係為a3(ρ-ρ') = 0.00003(a Vt)2 + 0.00021(a Vt) + 0.00575,其中ρ與ρ'分別為球體密度與沙拉油密度(0.90 g/cm3)。
再者,在相同半徑的條件下,密度越大的球體終端速度越大,在靜止下落後,越久達到終端速度。
The motion of a sphere which is falling through a fluid is subject to the fluid viscosity. In this study, we find out the relation between the radius of a sphere and the terminal velocity. We used a digital camera to record the sphere's descent in the oil. The three kinds of sphere we choose are acrylic(~1.18g/cm3), glass (~2.47g/cm3)and crystal (~2.66g/cm3). Frame-by-frame analysis of the video footage yielded rough estimates of the sphere's location within 1/30 seconds accuracy for statistically consistent results. By measuring the location and time and analyzing them, we find out the relation between the radius of a sphere and the terminal velocity. The expression of the drag force,Fdrag = -k1V, is not cosistent with our results. The study indicates the expression of the drag force should be Fdrag = -(k1V+ k2V2). The expression for the terminal velocities of the three kinds of sphere is of the form:a3(ρ-ρ') = 0.00003(a Vt)2 + 0.00021(a Vt)+ 0.00575, where a is the radius, ρ is the sphere density and ρ' is the oil density(0.90 g/cm3). In addition, if the radius is the same, the terminal velocity of a denser sphere is higher and the time to approches the terminal velocity is longer.
利用雷射光實驗研究液的折射率梯度
溶液和溶劑置於同一容器中,當溶質向上擴散時,會形成濃度梯度及折射率梯度 dn/dy,且dn/dy 對高度y 的關係圖會呈現隨著高度改變的現象。 半徑r 的D形容器,下方置溶液,上方置溶劑,以雷射光照射容器的平面部份時, 雷射光沿著法線出射,受折射率梯度的作用而向下偏Ζ距離,a 為容器至屏的距離, 得到dn/dy=Z/ar 的關係式;改變雷射光的高度y 可得dn/dy 圖。 以硫代硫酸那作實驗,其dn/dy-y 圖為以原始界面為對稱軸,因其擴散係數不隨濃 度改變;甘游水溶液的dn/dy-y 圖呈現不對稱,圖形的極大值往甘油方偏,主要係因 為甘油的擴散係數隨濃度的增大而減少。 我們成功第把不同時間對同一溶液的實驗結果予以模型化,得到的dn/dy-y 曲線隨 時間改變,並發現該曲線所涵蓋的面積為定值。 雷射光經光柵再照射半圓筒,可直接測出各高度的折射率,量出y、 dn/dy、n、及濃度可算出擴散係數。The mixing between a pure liquid and a solutionin a vertical column produced a concentration gradient , which in turn produced the refractive index gradient . As the solute particles diffused upward into the pure liquid , a gradient was generated because of the varying solute concentration . The plot of the refractive index gradient versus vertical position y (dn/dy vs y) is found to vary with time . A D-shape container of radius r is partly filled with a dense solution , and partly filled with solvent which is on the top of the solution. When laser beam pendicularly enters the flat surface of the container, the outgoing beam strikes the container at a normal incidence , and is deflected down a vertical distance Z by the refractive index gradient . We can get dn/dy=Z/ar , where a is the distance between the container and the screen . By changing the vertical position (y)of laser beam , we can get the plot of dn/dy vs y . We have successfully modeled the time dependent experimental gradient curves on the same solution . The area beneath the trace of dn/dy vs y at different time is found to be constant . Additionally, with a grating at the center of the semicircle, we can measure the index of refraction n and get the plot of n vs y. The diffusion coefficient D of the solute can be calculated using the plot of dn/dy,y,and time t.
溫泉中的秘密
The experiment was primarily focused on studying whether the enzymes from different bacterial species collected in various hot spring areas still exhibited activities at high temperatures. A further study would be conducted on analyzing the unique characteristics universally found in the genes of selected bacteria. First, hot spring samples were collected form Peitou and Wulai, and then cultured on the PY, PTG, MFB, and TS media in the laboratory. After the broth media growing with thermophilic bacteria, a series of continuous dilution method and solid-plate spreading were applied to separate these bacterial clones. The genomic DNA of the selected bacteria was extracted and used to analyze subtilisin-like gene by polymerase chain reaction (PCR) and electrophoresis. Finally, we examined the six selected thermophilic bacteria with the enzymatic activities of fibrin- and milk-protein degradation. We successfully concluded the experiment by proving that these thermophilic bacteria still exhibited significant enzymatic activitives in the high-temperature environments. The results of this experiment can be applied in numerous fields, for example, thrombus treatment and food processing, and a more in-depth study shall warrant the due consideration. 這次的實驗,主要是研究在不同的溫泉區中所採集不同種類細菌,是否酵素在高溫下仍具活性,如果有,再進而研究它們的基因有何特別的共同之處。首先,我分別自北投和烏來採集水樣,到實驗室後再以PY、PTG、MFB 和TS 四種培養基做細菌的培養,接著再利用連續稀釋和固態塗抹來做細菌的分離。經過挑選和培養之高溫菌直接進行DNA 的抽取,並利用「聚合?鏈反應」和「電泳跑膠」技術分析其類似蛋白質分解酵素subtilisin 基因。另外,本研究同時針對所選定之6 株高溫細菌利用血栓和牛奶蛋白來測試其蛋白質分解酵素的活性。由以上實驗結果可以證明某些細菌在高溫的環境下酵素仍具活性。這次在高溫菌的實驗結論,可應用在很多地方,例如:血栓的治療、在高溫下食品處理‧‧‧等,應用相當廣泛。
低溫二次燃料電池
本實驗係以台灣常見之數種植物(甘蔗、橡膠、破布子、苦苓)乾餾所成之多孔性碳棒鍍上銅和拷上Chitin 為電極兼電容,而以NaOH(aq)為電解液,製成化學電池。希望能研究出一低污染、低成本、能在常溫下經濟運作、並具有教學演示功能之電池。This research is based on the poromeric carbons which are made of several Taiwanese common plants (including: sugarcane, babul, Sabastan Plum Cordia [Cordia dichotoma Forst] , and Chinaberry tree [Melia azedadach L.]) by means of destructive distillation. The copperplating poromeric carbons later covered with Chitin functions as an electrode ac well as capacitance. Along with NaOH(aq) eletrolyte, a accumulator is then produced. The chief objective of this research is to produce a accumulator with low class of pollution and low cost, which is able to function economically under the normal atmospheric temperature. Also,this accumulator can serve as a teaching demonstration.
揭開變化球的神秘面紗 --- 探討丘腦至前額葉的路徑連結
During the evolution of humankind, development of frontal cortex has played a critical role, where higher brain function like emotions, self-consciousness, decisions…etc, were all related to frontal cortex. On the other hand, thalamus is usually associated with relaying the sensory signals from peripheral receptors. In order to understand the functional role of frontal cortex, the signal processing mechanisms in the thalamo-frontal cortical pathway became an important research issue. The aim of this experiment was to find a method to dissect a brain slice that contains a connecting route in vitro between thalamus and frontal cortex with functional activity. Through nerve fibers tracking technique using fluorescent-dye (DiI), it was understood that the 3D-space connection between thalamus and frontal surface was an upward curve with a turn of about 110 degrees and bending inwards from the two sides. If a conventional horizontal section was performed, the route would be cut-off and its integrity lost regardless of the direction. To solve this problem, a novel section method was developed to retain the route. Based on the route direction shown by the fluorescent-dye, a piece of brain block was cut and flattened of about 110 degrees. Other sections were performed as control for studying the effectiveness of the sectioning on the plane of the route. Finally, electrophysiological methods were used to verify the connection route was complete and functional. Thalamus-evoked extracellular field potentials in the frontal cortex were observed by changing stimulation strength, adjusting slice temperature and prepared oxygen supply and administration of drugs like CNQX and picrotoxin in the 110 degree flattened slice but not the others. It was found that the reaction was essentially a neuronal response, indicating the pathway between thalamus and frontal surface was retained substantially. With this novel brain slice technique, we can assess the functional connection between thalamus and frontal cortex and investigate the cellular mechanisms of the signal processing in this connection pathway. It is anticipated that present technique provides an important step to further elucidate the functional role of the frontal cortex. 在人類的演化史上,前額葉的發展扮演了極為重要的角色,凡舉情緒、自我意識、決策等,皆與前額葉有關。而丘腦通常與視覺、聽覺及本體感受如痛覺、觸覺、溫度覺的訊息傳遞有關。要了解前額葉的功能,丘腦到前額葉的徑路及訊息處理機制,便成為一個很重要的研究課題。本實驗的目的是尋找一個方法能在離體的腦切片上維持具有丘腦到前額葉連結的徑路並且有功能的活性。經由螢光染料(DiI)神經束追蹤技術,了解從丘腦至前額葉路徑的三度空間連結為一先向下再向上約110度的角度轉折,並同時先由內向外再轉向內的曲線,若用一般水平之切片方法,無論何種方向,其路徑必定會被切斷,不能保持其完整性。為了解決此問題,發展出一種可以保存其路徑的腦切片方法。依照螢光染料所顯示出的的路徑走向,在腦塊的皮質上切一刻痕,將腦塊以110度的角度展平,使其路徑處在一個平面上再切片。最後利用電生理的方法來證明所切出的連結路徑是完整且具有活性。改變在丘腦的刺激強度、調整腦切片(腦脊髓液)溫度、氧氣的供給以及施予藥物CNQX、picrotoxin,觀察其前額葉之電位變化,發現其反應確實為神經反應,表示從丘腦至前額葉的路徑已在這種特殊的腦切片中被完整保存。藉由這個方法,將有助於研究丘腦至前額葉功能性連結,神經網路結構,及其訊息處理機制,並期待以這樣一個全新的方法將來有助於瞭解前額葉的功能。
昆蟲也會大小眼!?
本研究目的主要在瞭解昆蟲的複眼(compound eyes)結構,比較晝行性與夜行性昆蟲複眼之差異,探討其視覺遠近和複眼結構的關連,及進一步觀察其對不同波長光源反應的差異。本實驗使用反射式及倒立式顯微鏡來觀察複眼及其小眼的結構,及觀察其成像情形,並使用攝影式接觸分析儀與放大管來探討視覺遠近和小眼表面曲率之關連,另外在暗室利用不同波長的光源照射蝴蝶以觀察其反應。實驗結果顯示複眼是由數千至數萬個小眼組成,小眼表面曲率半徑隨選用物種在25.3μm 至117.6μm 之間,蜻蜓複眼上半部和下半部小眼曲率半徑分別為30.6μm、117.6μm,印證了蜻蜓複眼上看遠下看近的說法,也發現蝦子小眼是正方形,其他實驗物種則皆為六邊形,而蝴蝶對光的反應程度則是隨波長漸增而遞減。The main purpose of this study is to understand the structure of the compound eye of insects, to compare the difference between the diurnal insect’s compound eye (apposition eye) and that of the nocturnal insect (superposition eye), to explore the relationship between the vision and the structure of the compound eye, and to observe the eye’s reaction to the different light wave length. In this study, a microscope (OLYMPUS BX51M) and an inverted microscope (OLYMPUS 1X71) were used to observe the structure of the compound eye and its ommatidia, as well as the resulting image. A contact angle measuring instrument (Dataphyscis OCA 20) and a microscope (Mitutoyo NAVITAR) were used to determine the connection between the vision distance and the facet curvature of ommatidia. The butterfly’s reaction to the light source with different wave length was also observed in a darkroom. It was observed that the compound eye of insects is composed of more than a thousand ommatidia. Among the subject insects, the facet curvature radius of their ommatidia ranged from 25.3μm to 117.6μm. The radius of the top and bottom half of a dragonfly is 30.6μm and 117.6μm. It confirms a scientific finding that dragonfly’s top compound eye focuses farther than the bottom half. The facet of each ommatidium observed is hexagonal in insects compared with the square shape found in the eye structure of shrimp. Regarding the reaction to light of the butterfly eye; the reaction decreased when the light wave length increased.
關於渦旋〈二〉
在做這實驗之前,我花了很長一段時間思考一個問題:我如何能得到同\r 樣大小(均勻)的水珠陣列?我在家中各個角落放置許多水瓶,看看哪\r 個地方能培養出顆粒相同的水珠? 往往肉眼見到整齊排列的水珠,一經\r 顯微鏡觀察,可就大小不齊整了。\r 第一篇中的實驗,幾乎是「水珠日記」,記載冷凝過程;其中我特地比對\r 「穩定的水蒸氣氣流」與「擾動的水蒸氣氣流」、「水蒸氣氣流與凝結盤\r 間溫度差別」、「凝結盤密度差別」、「凝結因子的重量百分濃度差別」、「水\r 蒸氣氣流之流速差別」,並加以複合比對。希望能找到產生均勻排列的條\r 件–探討水分子的自我組裝機制(Self Mechanism of Water Droplets)。\r 這其中提出『均勻假說』: 當條件合宜時,冷凝下降的細微水珠會產生\r free vortex ring,形成整齊的渦環組合,進而產生均勻排列的細微水珠陣\r 列。\r 實驗是藉由溶液密度小於水的設計,讓水蒸氣冷凝於液面上,並且因密\r 度較大而下沉。設計的要點是:儘量減少細微水珠自冷凝後的堆疊\r (coalescence),以呈現水珠原貌。\r 在第二篇實驗中,將對渦旋比例尺修正。渦旋本身難測大小,在空氣中\r 也不易觀察,但是若由水中觀看,可藉由空氣蕊長短估算。這次更進一\r 步考慮到排水速率、水深、排水口形狀、與極值。\r \r I have tried to ask a famous math professor if he can create a formula\r describing the ordered array of water droplets。〝Then, I should study Physics\r first !〞He said。\r Condensation is the thing we live with , being found everywhere, passing\r without notice。But we never know0 when it does start?\r This experiment presented here is actually the diary of the growth of water\r droplets through condensation。Through convection and vortex ring, it\r discusses the self assembly mechanism of water droplets and peep into the\r uniformity of the size of water droplets。\r Here, vortex ring plays an important role in the self assembly mechanism of\r water droplets which is not triggered in the daily life。\r By coalescence, water droplets grow bigger, but are not round again。We used\r the polymer film as template and designed the solution lighter than water, so\r the minute droplets will sink to the bottom and layer by layer。After seconds\r we may have multilayers of ordered array。\r This is the first step in discovering the uniformity of water droplets, besides, I\r made some correction to the Vortex-Ruler。Vortex-Ruler will be useful in\r researching the flying mechanism of butterfly and dragonfly as to judge\r which one induces more vortices。
總站該設在哪裡?—另類費馬點的研究
The definition of "Fermat Point" is that a dot, which lies in a triangle, has the minimum distance to the three apexes. In other words, "Fermat Point" has the minimum distance to three dots which are not on the same line. In the broad sense, then, in a N polygon, a dot which has the minimum distance to the N apexes could be named "Fermat Point." But what if we link up the N apexes and find out that they cannot make a convex polygon? The above is what we wish to fully discuss. Our inspiration comes from a paper on"Fermat Point." It just describes N convex polygon, so we think of putting the case to naturally polygon. The case may be that it is a concave polygon or part of the apexes which lies on the same line. We would not base our study on the conventional methods. Moreover, strictly defined, the repeated line segment will not be taken into account. That is, if the "Fermat Point" drops on the line with more than two dots on it, we just count the\r line segments except for the shorter line segments which were originally included in other studies. According to the theorem, our conclusions are as follows: 1. If N points lie on the same line segment, then the "Fermat Point"can be any point on the line segment. 2. If (N-1) points are on the same line segment, then the "Fermat Point" is on the point which two lines join together. One is that the line segment, and the other is the one which passes the remaining point and\r perpendicular to the first line segment. 3. Now there are (M+N) points. Among them, M points will make a M jog-polygon. The others all drop in the polygon. As the diagram shown beneath, we know that the "Fermat Point" drops on the point which two lines join together. The two lines must pass as many points as possible. 所謂的「費馬點」是指三角形內到三頂點距離和最小的點。換言之,「費馬點」就是到平面上不共線三點距離和最小的點。因此,我們可定義,廣義的「費馬點」即是n 多邊形內到各頂點距離和最小的點,亦即到平面上不共線n 點距離和最小的點,但若平面上n 點不能恰為n 多邊形的頂點呢?這就是我們所要討論的。由於我們的靈感來自一份關於「費馬點」的科展作品,所以我們想到,當平面上n 點不能恰為n 凸多邊形的頂點,甚或其中有一部分的點共線時,將不能以n邊形的方法來探討,但我們可以將之化為m 邊形內(n-m)個點來討論。而更重要的是,我\r 們增加了另一個限制,重複的線段將不被我們列入計算。亦即當所求點落在某一多點共線的線段上時,我們只計算該線段的總長,而不計其中重複的較短線段。根據這個原則,我們試行證明平面上三點、四點、五點及六點的可能情況,期望能從中找出足以推廣至平面上n 點的一般性。結果雖不完美,但我們總算差強人意的歸納出了下列結論:1.若n 點共線段,所求點可為所共線段上任一點。2.若(n-1)點共線段,則由該不共線點引一線與共線段垂直,其交點即為所求。3.若(n+m)個點中有m 個點為一m 多邊形的頂點,另外n 個點落在該m 多邊形內,則由兩個外頂點引直線盡可能通過最多點,該兩直線的交點即為所求。