全國中小學科展

2015年

口腔清潔-牙周致病菌(Porphyromonas gingivalis)對癌細胞生長之探討

牙周致病菌(Porphyromonas gingivalis)普遍分布於大部分人的口腔中,而牙周致病菌的熱休克蛋白GroEL在先前研究指出與牙周病和發炎有關;再者,研究證實了牙周病和癌症的相關,但尚未證實GroEL是否會增強腫瘤的增生。本研究藉此探討GroEL與腫瘤增生的相關性。結果顯示,小鼠被施打GroEL後,腫瘤體積明顯增加,死亡率也上升,並且血液中血管內皮前驅細胞的含量也增加,免疫組織染色法的結果也呈現出施打較高量之GroEL會使腫瘤內有較多血管的分佈;雞胚蛋的實驗中,更證實了GroEL會增加血管的生成。總結上述結果,推論P. gingivalis的GroEL會增加癌細胞的生長速度,而其機制可能來自於增加血管內皮前驅細胞的含量,刺激了血管的新生,提供了癌細胞生長的養分。所以口腔清潔,除了消除異味外,更可以預防癌症的發生。

星系演化? 剖析巡天資料庫驗證星系顏色與紅移關係

透過研讀論文Strateva et al. (2001;簡稱S01),開啟了我們對於星系的星等、星色考量紅移情況下之關係的興趣,並展開以下研究。S01利用Sloan Digital Sky Survey (SDSS)所提供的測光數據,首次依據顏色u*-r*,將星系解析為偏紅以及偏藍兩個族群。本研究藉由SDSS最新提供的光譜資料進一步取得精確紅移數據,經由 K-correction復原靜止坐標系中各星系的星色,並可透過距離模數消除距離對於星系亮度的影響。因此,本研究得以分辨出兩類星系族群的紅移演化。我們發現紅移效應和星系本質的特性對於 r*<17.77且z<0.3的星系有顯著的影響。在研究目標範圍內,兩類星系族群皆沒有發現紅移演化對於顏色的影響。本研究也與 S01作比較,討論了分析中可能的誤差來源。

Novel Approach to Screening Mutations Causing Retinoblastoma, a Childhood Cancer of Retina

Retinoblastoma (RB) is a childhood retinal cancer caused by mutations in the RB1 gene. Molecular diagnosis is crucial for early detection and treatment. Current DNA diagnostic screening requires substantial amounts of tumour and blood samples. However current screening methods face the challenges of limited DNA templates from minute retinal tumours and too much blood samples drawn from young patients. In addition, the starting DNA template amount and quality are important to ensure confident detection of disease-causing mutations. As the majority of RB1 mutations are unique and distributed throughout the RB1 gene with no real hot spots, the entire gene needs to be thoroughly analysed. This investigation proposes to enrich DNA samples using a whole genome amplification (WGA) step prior to RB1 mutation screening by RB1 gene-specific PCR amplification as well as high resolution melt (HRM) analysis and sequencing. It also identifies RB1 mutations in two RB patients and explores whether WGA and saliva products can be a source of DNA templates for RB1 analysis. In addition, this study was conducted based on the hypotheses that RB1 mutations were the underlying cause of the disease in the two patients, and that the products from WGA could be used specifically for RB1 gene analysis to overcome the constraint of insufficient DNA samples. Two anonymised genomic DNA samples from two unrelated RB patients and five normal healthy DNA samples were used in this project. WGA kits were compared according to three criteria, namely amplification yield, product fragment size and whether DNA is amplifiable. Prior to and after amplification, the optical density of two normal samples was measured to determine the increase in DNA yield. The amplicons were subjected to gel electrophoresis to determine the product fragment size. Exons 6, 14 and 25 of the original and amplified samples undergone PCR, and were examined again using gel electrophoresis to ascertain that the amplicons were amplifiable. Mutation analysis using HRM was carried out with pre-existing primers for all 27 exons and the promoter of RB1. Samples from patients were analysed against 83 saliva DNAs extracted using Oragene•DNA (OG-500) Kit. REPLI-g was observed to produce higher yield and products of reliable fragment size. Single distinct bands were also seen for exons amplified using REPLI-g, indicating that REPLI-g is more accurate and suitable in the amplification of DNA. Abnormal melt profiles were obtained for exon 6 in RB477 and exon 14 in RB572 for HRM. These exons were sequenced to determine the exact mutation. Exon 6 was found to have a splice-site mutation g.607+1G>T, while a point mutation, g.1363C>T (p.Arg455X) was identified in exon 14. Both the uses of saliva as a non-invasive DNA source and the WGA approach for enriching DNA sample for application in RB1 gene analysis have never been reported for RB. Although HRM analysis has been used for other diseases, this is its first instance applied in work on RB1 gene. In short, this report offers novel and promising approaches which would contribute significantly to the molecular analysis of mutations in RB.

Exclusion Zone Water現象的探討

Exclusion zone water現象係指在水溶液中膠體粒子等大型溶質無法靠近多種親水性表面,形成數十到數百微米厚的「空乏區」,簡稱為EZ。目前提出的理論認為此處形成了特殊結構水,然而我們的實驗使用磁珠卻可穿入EZ區,發現不符原理論預測。因此我們提出EZ是由擴散滲流 (diffusiosmosis) 與擴散泳 (diffusiophoresis) 綜合造成的想法來解釋。我們設計了一些實驗,觀測溶液中EZ大小變化、膠體粒子流場與離子濃度梯度等,皆符合預期並成功證實我們的想法。應用此研究結果,可發展新的溶質過濾萃取方式,或利用離子交換產生的流場作為新的發電方式。

Geographic Belts for Hurricane Landfall Location Prediction

When predicting a hurricane’s landfall location, small improvements in accuracy result in large savings of lives, property, and money. The project’s purpose was to apply a breakthrough method that can predict the geographic location of a hurricane’s landfall with high accuracy. Researchers have known for a long time that there are strong correlations between a hurricane’s landfall location and the geographic regions its track passes through. However, no methods have been developed to mathematically and explicitly describe these correlations. Consequently, the correlations can only serve to meteorologists as vague guidelines for their guestimates and are not usable in making practical forecasts. By studying the correlations and performing numerical optimization on historical hurricane data, this research discovered a set of geographic belt regions in the Gulf of Mexico that can be used as landfall location predictors. When a hurricane passes through any one of these belt lines, a prediction can be made by extending the hurricane’s moving direction vector towards land – the intersection point of this extension line with the coastline is the predicted landfall location. This prediction method is simple and straightforward. It only uses basic measurements from meteorological satellites: the hurricane’s real-time locations and moving directions. In conclusion, when compared to existing methods, the predictive belt method (PBM) created in this research provides a landfall location forecast with higher accuracy. Verification with historical hurricane data demonstrated that the PBM’s average error is less than 50% of the National Hurricane Center models’ error.

miRNAs在光形態發生中的影響

在種子萌發的階段,光會造成幼苗的形態變化,稱為光形態發生(photomorphogenesis)。然而microRNA (miRNA) 如何影響光形態發生,一直未被詳細探討。藉由次世代定序 (Next Generation Sequencing)之結果分析,得知阿拉伯芥 (Arabidopsis thaliana) 幼苗中,具有受光調控的miRNA。利用北方墨點法 (northern blotting) 及即時聚合酶鏈鎖反應 (Real-Time PCR) ,我們驗證了miRNA和其降解目標之相關性。在篩選過後選得miR396s和miR858s,作為後續研究的目標。下一步便是了解他們的功能。目前已經證明miRNA及對應目標基因的突變株確實會影響花青素、葉綠素累積,下胚軸延長及子葉發育。考量到miRNA有功能性的替代物 (functional redundancy) ,我們於是進行標的序列模擬(target mimicry) ,以削減miRNA之功能;也在建立大量表現上述miRNA之轉殖株,了解其與光形態發生之關聯。最終目標為解開miR396與miR858對光形態發生的調控機制。

似彈簧的卷鬚構造對藤本植物的作用與影響

瓜科植物的卷鬚分為基部與末端螺旋,兩者方向相反,中間以逆向纏繞區相連。基部螺旋的螺距與螺寬較大,是一種較大型的彈簧。由形態數據推導出彈簧指數C,結果為基部螺旋的C值較大,受力作用後形變量較大。利用虎克定律探討彈簧常數K,結果為末端螺旋K值較大,是一種剛硬度較大的彈簧。將卷鬚切片染色後發現,膠質纖維(G-fiber)細胞與厚角細胞分布於螺旋內側面,在迴旋盤捲時逐漸生成。由於『纖維帶不對稱木質化程度』與『螺旋不對稱柔硬組織分佈』,造成莖兩側不對稱收縮力作用,讓彈簧狀的卷鬚形成。而基部與末端螺旋有不同彈簧性質的原因,是因為兩段螺旋的『膠質纖維不同含量』及『纖維帶木質化程度』不同,造成卷鬚內部彈性與收縮力的差異所致。

水電交融

本實驗為將高電壓的靜電通入流動的水中,發現下端水柱產生雷利不穩定性,以及在特定條件下發生甩動。水柱被截斷成水滴後,因電場作用而散開,造成視覺上一錐形的區域。 本實驗探討(1)水柱長的變化 (2)水滴個數的體積個數密度 (3)直徑分布隨著錐形區域位置的變化 (4)水滴帶電量與體積關係。 尺度及各變因為:水流量0.4~2.0cm3/s,電壓0~30kV,電流0μA~12μA,不同導電度和表面張力的液體。實驗結果: (1)水柱長隨電流成指數衰減,並提出h=Ae-bI+kQ之經驗公式 (2)水滴分布範圍隨電流與流量增大分別增大與減小 (3)錐形區域越外圍水滴越小 (4)使用的蒸餾水水滴帶電量與體積之2/3次方成正比

Androcopter, using smartphones as flightcontrollers for Quadrocopters

This project proposes that smartphones are capable of steering a quadcopter, doubling as a flight controller unit. This means that sensor results from the smartphone’s IMU (inertial measurement unit) are compared with steering commands from the pilot received over Wi-Fi or a RC-transmitter. The idea behind this project was to build a cheap flight control for a quadcopter. Smartphones seemed to be the perfect device because of their dominance in the market. The first step was constructing the quadcopter’s frame. I first designed the frame on AutoCAD and then built a prototype out of aluminium. My search for a possibility to connect the engines or low level peripherals to a smartphone led to the «IOIO-Board». After collecting sufficient information about sensor fusion and control theory I started working on my own controller. Due to the frame’s large size the quadcopter is very stable and best suited for aerial photography. Engine control by smartphone using an «IOIO-Board» is fast enough for flight. A smartphone possesses everything needed to control a quadcopter. The disadvantage of using a smartphone is that the processor has to calculate multiple applications simultaneously. This makes it more difficult to guarantee the correct timing of operations. Nevertheless, external influences such as phone calls do not influence the flight behavior of the quadcopter. As work in progress I have experimented with the implementation of GPS and an onboard camera.

仙「鋁」奇「圓」-探討鉻鋼球碰撞的力與能量

本實驗主要在探討鉻剛球碰撞產生的情況與能量的傳遞,我們改變的變因有: (1)球落下高度、 (2)鉻剛球大小(兩種規格)、 (3)兩球撞擊的中間物材質(鋁箔、白紙、銅片)、 (4)中間物材質的厚度。 發現球自愈高的高度落下後產生碰撞,中間物(置於底下鉻剛球的上方,如:鋁箔)所產生的同心圓面積愈大;而大球相撞產生的同心圓也比小球相撞所產生的大。就碰撞後反彈高度而言,大球碰撞後反彈高度比小球碰撞後反彈高度來的高。與銅片有相同厚度的6層鋁箔,其碰撞產生的面積與銅片的卻不相同,可見不同材質的硬度及彈性,亦是影響面積大小的因素之一。