物理與天文學

This paper describes the investigation of a fascinating physical phenomenon called the “floating water bridge”. Despite the fact that water is undoubtedly the most important chemical substance on earth, it is practically ubiquitous and it still represents one of the best explored substances, still not all characteristics are well-understood. There are some phenomena like the “floating water bridge”, which cannot be explained. If high voltage is applied to two beakers, which are arranged close to each other and which are filled with deionized water, a connection forms spontaneously, giving the impression of a floating water bridge. For the experiment discussed in this paper, two beakers with a diameter of 50 mm and a height of 80 mm are filled with triply deionized water. Platinum electrodes are submerged in the center of the beakers, one set to ground potential (anode), the other one on high voltage, up to 25 kV dc. Within the scope of this work, an experimental setup was developed, which enables measuring and demonstrating the most important parameters like voltage, current, length and temperature of the water bridge as well as the mass transfer between the beakers. In addition the correlation between the different parameters and the influence on the water bridge could be estimated. Once the beakers are separated, the bridge remains stable for several hours up to a length of 2.5 cm. With platinum electrodes and no electrolysis observed, a small current (≈300µA), a mass flow from anode to cathode and forces were measured. Pictures, taken with an infrared camera and a new developed method to record "infrared-videos", enabled to visualize the heat flow in the water bridge. Furthermore the conversion of energy and the dependence of charge and mass transfer could be estimated roughly. In the course of the investigations it was also tried to prove the water bridge with other liquids like castor oil, olive oil, a mixture of glycol and water as well as tap water - for some of them for the first time. Supplementary the experimental setup was varied by using different electrodes with different sizes and different material as well as beakers of different sizes and materials. In addition, a qualitative explanation was developed. The results of this work enable a better understanding of the floating water bridge and provide a basis for further research as well as for development of future practical applications. One of these applications could be an improved waste water treatment process.

The phenomenon of pedestrians nowadays is still found. Due to frequent walking, sometimes our legs feel tired and hard to move. This is become the basis for developing tools that are convenient for pedestrians. An easy tool for humans is needed for our activities, especially walking. The Synergy between our hands and feet provides a big and significant contribution to the appliance. Normally, the movement of our hand gets along with its motion with a different side of the foot. When the right foot step, then the left hand is swung forward, and vice versa. The tools can be developed by utilizing a variety of systems. The system includes the tools concentric wheel and axles system, spring system, and pulley system. The concentric wheel and axles system is useful in controlling the rope. Movement on the rope could activate the entire system on the appliance. Wheel that related with the hand is three times bigger than wheel that related with pulley that is applied on foot. Spring system is able to lighten the pressure of the foot with a given upward force, and able to provide downward force when the spring returned to its original position. While the pulley system on the tool used to provide mechanical advantage two times is also useful to lighten the pressure of the foot when walking. The tools can be designed with simple, and able to provide benefits to users. By trial and error, it shows that the tool is able to lighten human’s activity when they walk. The tool can be able to lighten the leg’s load by utilizing arm muscles work. Utilization of the arm muscles which helps to ease the pressure of the foot can provide more benefits. One of them is that it can strengthen the arm strength, so the tool can be used as sport equipment. Utilization of the tool can also be reserved for special people who have difficulty in walking due to an accident or birth with leg defect.

本研究主要探討水滴在高溫鋸齒面上之爬坡現象。實驗中發現在高達四百度的鋸齒面上能形成懸浮水滴，且水滴可持續一段時間而不會立即蒸發，在水平之鋸齒面沿特定方向移動，特別的是，水滴甚至沿著傾斜之鋸齒面向上運動。首先，水滴因受熱在周圍形成一層蒸氣層，阻隔熱的傳遞，使其不會立即蒸發。實驗中改變鋸齒齒廓之兩斜邊的比例，可以驅動水滴往長斜邊所面對的方向運動。進一步實驗顯示，水滴內部的流動趨勢分別為：水滴前端呈順時針方向流動，而水滴後端則呈逆時針方向流動。此外，爬坡中的水滴，其後半部具有較高之蒸發速率，經由設計一個類比的實驗，我們發現，在高溫金屬平面上，透過其平面上的一個凹槽，可以控制水滴前後部位蒸發速率的差異性，也造成水滴向上爬坡的結果。由實驗結果證明，蒸氣壓力與氣體運動對水滴造成的摩擦力為驅動水滴爬坡的力量來源。

將水加入溶液上方會造成溶質向上擴散，而造成濃度和濃度梯度的變化。我們使用簡易的實驗儀器算出不同時間各位置的濃度和梯度變化。書上大多假設濃度梯度成鐘型曲線分佈的簡單模型描述擴散過程，但只能用在擴散係數為定值的情況。從實驗或參考資料顯示，擴散係數會隨濃度而變，因此擴散現象常呈現非高斯之分佈，故我們以自己設計的實驗分析溶液在較高濃度時的「非高斯型擴散」，直接測量並計算不同濃度下的擴散速率、擴散係數。研究分子擴散行為理論未完全建立，擴散目前屬於半實驗的科學，此實驗設計與分析方式可供作擴散理論發展的參考。

人眼所見點光源四週的光芒（我們稱為"星星長角"），夜間瞇眼時所見向上下方向射的特別長的光芒（我們稱之為"炫光萬丈"），這二種視覺中的光學現象無法用相機拍攝，但眼睛卻能夠看見。書上及網路上均無法找到合理的解釋。因此，我們設計了數個實驗來研究這些光學現象的成因。我們發現了星星長角的成因是由光對眼睛表面刮痕的繞射和光對眼睫毛的繞射雙重原因所產生。而炫光萬丈的成因則是光線經過眼球表面淚膜層的部分反射及部分折射所造成。The purpose of the research is to verify possible reasons of some optical phenomenon in human vision, including the star shape of a dot light source and glare upward or downward when one narrowing his/her eyes. These optical phenomenon can be seen by naked eyes but can not be taken photos with a camera. We find no detailed explains which can explain the cause of glare upward or downward on the internet or in books. So we designed several experiments trying to find out the cause of these optical phenomenon . In experiments, we figured out that diffractions by notches on the surface of eyes and eyelashes are both responsible for the star shape of a dot light source. The cause of glare when narrowing eyes is that partial reflection and partial refraction of light take place between boundary of air and tear film and boundary of tear film and cornea. The appearance of glare is closely related to the thickness of the tear film . When we narrow our eyes , the tear film is thicker. The thicker the tear film is ; the longer the glare is .Also, bended extent influence the length of glare. We figured out that the more bended the tear film is ; the longer the glare is.

In this work, techniques to explore the capabilities of multi-walled carbon nanotubes\r (MWNTs) in sorting nanoparticles (NPs) were presented. A droplet of a solution comprising of quantum dots (QDs) with various sizes was deposited on an aligned array of intertwined MWNTs. Photoluminescence (PL) and fluorescence microscopy (FM) revealed that MWNTs were effective nano-sieves that could effectively sort out QDs with a size difference of ~ 2.1 nm.\r Cadmium Selenide/Zinc Sulfide (CdSe/ZnS)core-shell QDs and Cadmium Sulfide (CdS) QDs were used to explore whether chemical properties of NPs affect the sieving capability of MWNTs. Further investigation on the effects of micro-patterning on the sieving ability of MWNTs was also carried out.PL and FM results suggested that micro-patterning could aid in separation of QDs and thus improve sieving capability of MWNTs. With the above findings, QDs emitting different colors as a result of size difference could efficiently be assembled onto the MWNTs en route to three-dimensional architectures with controlled assembly of NPs.\r Together with controlled laser power to remove desired amounts of QDs decorated MWNTs, a multi-colored display could be achieved. Further experiments were also carried out to determine the feasibility of introducing MWNTs as filters for NPs. Dilute solutions containing NPs such as gold colloid was run through these MWNTs filters by gravity. Field emission scanning electron microscope (FESEM) images of the samples showed that MWNTs were successful in trapping the nanoparticles. Explorations into the length dependent effect of using MWNTs as filters, suggested that 300μm MWNTs are better nano-sieves compared to 50μm MWNTs.