全國中小學科展

依國際科展年度查詢

2002年

Bio-Active Plants

My Science Fair project last year tested a local native plant for it’s toxic effects on insects (fruit flies), bacteria, fungi, and viruses. The root of the plant Lomatium dissectum, had been used by the Salish People to control lice and other insect pests in horses and cattle. The root was also used to kill fish, which could then be harvested by women and children. The fish killed in this way were not harmful to eat as long as they were consumed soon afterward. I have found also that fishing with the aid of plant toxins was formerly very common in tropical Africa. \r Lomatium dissectum, grows in dry rocky slopes in conjunction with Sagebrush.\r Many desert plants produce toxic substances that inhibit the growth of competing plants\r nearby. This adaptation is called Allelopathy. In a natural ecosystem, Lomatium does not\r kill fish because it does not grow beside creeks. But this raises the question of whether\r allelopathic plants growing outside their natural ecosystem are having a toxic effect on\r animal life. There are introduced invasive weeds that are allelopathic, such as\r Knapweed,growing near streams. And there are crop plants that are allelopathic – Rye and\r Alfalfa. Do these “natural herbicides” also kill fish? Walnut trees are allelopathic and\r compounds from Walnut kill fish.\r If this effect does go beyond toxicity to other plants, it would be an important\r consideration to environmental guidelines for private land bordering on streams and\r rivers. The B.C. Ministry of Environment notes the importance of shade cover for\r spawning streams. It does not recognize the harmful effects of introduced plants. Yet,\r when we were purchasing supplies for our Koi Pond the pet supply company offered a list\r of “Some of the Worst Plants to Have Around Koi”. We do not know if the introduced\r allelopathic plants are poisoning fish or reducing fish stock by poisoning the food that fish\r need.\r Science Fair rules do not allow any research that is expected to have any negative\r impact on vertebrate animals. Because of this, I have decided to test the effect of\r allelopathic plants on fruit flies (Drosophila). Fruit flies are similar to fish since, during\r larva and pupa forms, they live in direct contact with their culture media. I will also be\r testing the effect of allelopathic plants on Planaria (Turbellaria), an aquatic invertebrate.

磁流體的浪潮-磁場梯度下磁流波紋之研究

在本次實驗中,我們發現在不同厚度的磁流體薄膜中,會因本身磁性粒子結合,而呈現不同的影像圖形。隨著薄膜厚度增加,其磁性粒子會由鏈狀排列成塊狀叢集,可是一旦外加磁場後,又要全部轉向磁力線方向集結。另一個發現是將磁流體薄膜放在一個不均勻的磁場梯度中,則樣品內的磁流體粒子,不僅會隨著磁力線的方向排列移動,更會出現磁流波紋,其行進路徑是沿著垂直於磁力線的方向,向磁力線密集處移動。我們亦發現在不同的薄膜厚度及不同外加磁場下,其”磁流波紋”的波速亦會隨之改變。一般而言,樣品的厚度愈厚,或外加磁場愈大,其”磁流波紋”的波速愈快,反之則愈慢。最後,我們列出了一些磁流波紋的應用,相信是精采可期!In this experiment, we find that in different thickness of magnetic fluid different images will appear, because of the connection of magnetic particles. With the increasing of thickness the magnetic particles will change its shape from chains to blocks. But when we add external magnetic field, they will get in line one by one to the direction of magnetic line of force. We also find that we put the magnetic fluid film in the uneven magnetic gradient, the magnetic particle in the sample not only follow the direction of magnetic line of force but also show the “magnetic wave”. Its move path is perpendicular to the direction of magnetic line of force. In the different film thickness of magnetic field, the wave velocity of the “magnetic wave” will change. In generally, the thicker the sample is, or the larger the magnetic field is, the faster the wave velocity of magnetic wave is and adverse is true. At last, we list the applications of “magnetic wave”, we believe they are marvelous!

電蚊拍挑戰A!

本研究以碳化矽(SiC)奈米粉末加入去離子水中,插入銅電極加以電壓進行其表面帶電性的研究。研究中發現SiC奈米粉末的表面帶有負電荷,且加以電壓後,SiC奈米粉末會沉澱下來。利用場發射掃描式電子顯微鏡(SEM)及X-光繞射儀(X-RD)檢測其性質,發現加以電壓使奈米粉末失去電荷而聚集沉澱。同時經由製作不同酸鹼度SiC奈米粉末溶液的陽極極化曲線發現pH值越大,SiC奈米粉末表面電位越高,開放電路電位越小。本研究實驗過程中發現pH值2之SiC奈米粉末溶液加過電壓後,正極生成一透明薄膜狀物質,極有可能是導電鍍膜,應用價值極高。本研究已先進行微硬度試驗與金相實驗,將由長庚大學機械系研究所進行更深入檢測與研究。The electrochemical behavior of the SiC-nanopowder in deionized water was studied. The electrochemical cell was composed of two pure copper electrodes, across which different voltages were applied. The morphology of the nanopowders or even with reacted products was examined using field emission electron microscope(FESEM) and the corresponding phases were identified with X-ray diffraction method(XRD). The experimental results show that tha nano-powders precipitated at the surface of the anodic copper electrode and in the same time the nanopowders in the solution aggregated when 20 volts were applied across two electrodes. That is, net negative charge could be induced around the nanopowder. Deposition rate of the aggregated powders in the various pH-value solutions was evaluated and the aggregated powders were examined with FESEM. The higher Zeta potential of the SiC-nanopowder was examined as the nanopowders immersed in the higher pH value solution. The nanopowders aggregated themselves as the pH value under 2. The anodic polarization behavior of the copper electrode in SiC- nanopowder solution was measured and the results were compared with the aforementioned tests.

Palatability Tests on Rana Chalconota Tadpoles

The skin of amphibians can secrete poisons from glands which reduces Palatability or sometimes result in rejection by predators. My research serves to confim the hypothesis that the pair of glands located on the ventral side of Rana Chalconota Tadpoles acts as an anti-presatory structure. Their palatability was measured by the consumption of them at developmental stages intermediate and post-metamorphic by Channa gachua and Giant Dragonfly Nymph. A known-palatable tadpole, Rana malesiana, was used as a control.

機能性材料的光學性質

本實驗使用磁流變流體(Magnetorheological fluid, MRF)來估查其磁場作用下的光學性質。本實驗採用Lord公司的MRF-132LD磁流變流體加以稀釋到不同的重量濃度,並以氫氟酸蝕刻玻片產生不同的厚度。吾人觀察到濃度參數以及厚度參數均對MRF薄膜的光繞射產生影響。膜厚越薄,產生的繞射較明顯,而重量濃度較小的容易亦有較大的繞射角度。吾人亦移動上下兩玻片相對位置,施加剪力的作用,繞射現象也產生明顯的改變。\r The Magnetorheological fluid (MRF) is used to observe the optical properties under the vertical magnetic field , The MRF-132LD from Lord Company is used, The MRF is diluted to different weight ratio of particulate and carrier fluid . The different thicknesses of the MR thin film are also made with the diluted MRF. The concentration of the MRF and the thickness of the thin film are both found to have significant effects on the optical diffraction phenomenon. The optical diffraction is also found to be affected by the applied shear force to the thin film.

Improvement orchard Soil Ecology by Sustainable Cultivation

1.Purpose of the research We observed frequent application of chemical pesticides and herbicides at the pear orchards near our school. Our concerning questions are the influences of agricultural chemicals on soil ecosystem which may be slowly deteriorating. There are many other orchards where the farmers are practicing environmentally-friendly agriculture using organic fertilizers such as composed manure instead of sycnthetic fertilizers. The purpose of this research is to examine chemical and mocrobiological quality of the orchard soil. We report biological control of pear disease using antagonistic microorganisms and suggest improvement of soil quality as a result of nature friendly agricultural practice. 2.Procedures and Data Two orchards were selected: Conventional fertilizers and chemical pesticide application farm; Environmentally friendly farm using organic plant manure and biological control of disease. Several different aspects of soil micro-flora, indicator microorganisms, physiological characteristics of pear fruit, residues of synthetic chemicals in the soil, soil chemical properties were examined. We could observe that use of organic manure and biological control agents for disease control by indigenous microorganisms improved biological and chemical quality of the orchard soil. Results are summarized as follow: A. Microbial diversity could be observed in organic farming orchard soil. Among 42 fungal genus, 7 species of penicillium including P. decumns, 3 Alternaria species, 4 Fusarium species including Fusarium graminearum, 6 Aspergillus species including Aspergillus niger were identified. In case of bacteria, 59 samples were isolated and 17 genus including Cystophaga johsonae were identified. B. Beneficial indigenous bacteria having several biological functions were isolated: Enterobacter intermedium produces organic acid therefore this bacterium can solubilize insoluble phosphate. Several Pseudomonas species were isolated. These bacteria produce iron chelating compound under iron limited environments and can control plant disease. Interestingly, we could find indigenous biocontrol agent Hypocrea vinosa which can effectively control black star disease on pear surface. C. We have formulated ten different microbial-pesticides using several combinations of indigeous microorganisms such as Hypocrea vinosa, Trichoderma atroviride, Rhizopus microsporus etc. These microbial-pesticides could inhibit 100% of black star disease on pear surface which showed similar inhibition effect as commercial pesticides indicate that these microbial-pesticides may replace synthetic chemicals in the near furture. 3.Conclusions Our research demonstrates the eco-friendly organic farming system could improve soil eco-system of pear orchard, where no synthetic fertilizers and pesticides are applied. As a result of manure application, the soil chemical properties are more stable and microbiological flora was more diverse. Use of microbial and bio-pesticide resulted in strong inhibition of black-star disease incidence on pear surface. We suggest that eco-friendly farming systems are needed to diminish environmental pollution in soil and water caused by frequent and abundant use of agricultural chemicals.

The Neem Dream: "Nature vs. Malaria""

The purpose of investigation was to find and test an inexpensive and effective remedy against malaria. After a great deal of research, I learnt that an effective herbal remedy against malaria may be extracted from Neem (Azadirachta indica)leaves. This remedy is not very well known about all around the world, however, the Neem tree is found in many parts around the world and is therefore a very accessible and inexpensive remedy against malaria. The purpose of my project was also to inform people about the harmful effects of malaria on the human body, as well as to advise people on how to protect themselves.

台灣桃園縣虎頭山的泥裂痕的分析和研究

桃園虎頭山是位於林口台地南端的低海拔(約240~260M)丘陵地,表土層屬於紅土層,紅土主要成分為細沙(直徑>50μm,約佔50%)、粉沙(直徑2~50μm,約佔30%),其餘以黏土為主,加上少量含鐵礦物,採樣地點字圖二中的三聖宮旁的登山步道,其坡面面向東南方,對位處北緯25度的桃園屬於向陽波,經日曬適當時間後所產生的龜裂現象,是我們探討的對象;We have focused the study on the sun cracks found in the Mts.Hu-To are located in the southern part of the Mesa Lin Kou, which are 240m to 260m above the sea level. Mainly red clay, the surface soil is a composition of fine sand(diameter>50μm,up to50%)and silt(diameter>2~5 μm,up to 30%),including clay and a limited amount of iron minerals. The soil sample was gathered at the trail beneath the Hil Gue-Lun(241m,see pic.1)from the southeastern latitudes.

CANE FOR BLIND

The main reason for the creation of the project was looking for the uncondutuinal support for the entire handicap people that reside in the whole world. \r In all the communities there are barriers that oppse the total development of these people, and what currently exists can not help achieve a full lige for example: it's hard to have a basic education, a productive employment, or in their case to have a simple normal life.\r at the present time there is a serious problem of inequality, this is presented beacuse there has not been a mechanism that has been albe to please 100% of its real demand. That's way what we seek with this prototype, to be able to help them to have and live a better quality of life, it has the function of warning them when an object is near or before them emitting a brief sound that dose not cease until the way is completely free of obstacles, it is also sought to prevent accidents lkie falls, trips, among other, and also to help create more accsess possibilities to help any people that suffer any kind of handicap.\r This is a prototype that is able to help blind people, by heping them become able to move from one place to an other more faster and more securely, these is trying to make them more sure and reliable on them self, also the project is very economical and it was created due to the high quantity of blind men and women that exist in the whole world

棋盤的費伯那契

在學校科研營的教材中,有一個題目,其內容相當於:「在一列格子中 放入黑棋與白棋。白棋不可連續放置,而黑棋不受此限,請問共有幾種可能的排列方式?,在此規則下,若將格子推廣為m列n行的棋盤,那又如何呢?我們對此好奇不已。