Issue 030, 2025 SCIENCE FOCUS Can Asteroids Serve as a Food Source for Astronauts? 小行星能成為太空人的食物來源嗎？ The Tiny Invaders in Your Home: Dust Mites 家居的微小入侵者：塵蟎 The Versatile Baking Soda: From Baking to Graffiti Cleaning 多用途的蘇打粉：從烘焙到清除塗鴉 How to Eat a Pizza Slice Properly? 如何不失禮地吃薄餅？ Q&A with HKUST Physics Majors 讀物理系的人：與科大學子對談
Dear Readers, Welcome to a new issue of Science Focus. The end of the academic year is on the horizon. In the summer, I hope our articles will stimulate extended learning in science, not just for exams, but for fun! In this issue, we bring you two contrasting stories on food. It is up to you to decide if you prefer pizzas or asteroids for dinner. Moving onto yet more domestic issues, we consider the many ways to use baking soda and the harmful effects of dust mites when they invade your home. Do you know that dust mites are not insects? On physics, we tell the story of a lab accident that led to the invention of laser eye surgeries. We also connect with past and present HKUST physics students, who shine in different arenas. Finally, I am excited to report a record number of entries to this year’s “Science in Cha Chaan Teng Food” Writing Competition. The winning articles would surely stimulate interesting conversations in your next visit to cha chaan teng. Many congratulations to our prize winners, and I am sure they will appreciate your support and comments on Instagram. Yours faithfully, Prof. Ho Yi Mak Editor-in-Chief 親愛的讀者： 歡迎閱讀最新一期《科言》！本學年即將結束，在暑假裡希望我們 的文章能鼓勵大家探索課外的科學題材 — 不為考試，只求樂趣！ 今期我們會為大家講述兩個截然不同的食物故事：晚餐您想吃薄 餅還是小行星呢？接著關於家居的題材，我們會介紹蘇打粉的各種用 處，以及塵蟎入侵家居所帶來的有害影響。您知道塵蟎不是昆蟲這個 冷知識嗎？在物理範疇，我們會細說實驗意外導致激光矯視誕生的故 事，亦會與現在和過去的科大物理系學生對談，讓大家認識在不同地 方閃閃發亮的科大人。 最後，我很高興宣佈「茶餐廳美食的科學」寫作比賽的參加人數 再次打破歷年紀錄，得獎作品定能給您靈感，啟發您在下次到訪茶餐 廳時與親朋好友展開知識性的對話。在此恭喜各位得獎者，相信他們 會感謝大家在 Instagram 上的支持和留言。 主編 麥晧怡教授 敬上 Message from the Editor-in-Chief 主編的話 Copyright © 2025 HKUST E-mail: sciencefocus@ust.hk Homepage: https://sciencefocus.hkust.edu.hk Scientific Advisors 科學顧問 Prof. Ivan Ip 葉智皓教授 Prof. Kenward Vong 黃敬皓教授 Prof. Yi Wang 王一教授 Prof. Chi Wai Yu 余智偉教授 Editor-in-Chief 主編輯 Prof. Ho Yi Mak麥晧怡教授 Managing Editor 總編輯 Daniel Lau 劉劭行 Student Editorial Board學生編委 Editors 編輯 Sam Fan 樊潤璋 Roshni Printer Devandhira Wijaya Wangsa Helen Wong 王思齊 Jane Yang 楊靜悠 Daria Zaitseva Social Media Editors 社交媒體編輯 Audrey Chan 陳皚慧 Daisy Yeung 楊于葶 Graphic Designers 設計師 Jacky Lau 劉重信 Yerim Song 宋禮林 Winkie Wong 王穎琪 Constance Zhang 張粲璨 Contents Science Focus Issue 030, 2025 What’s Happening in Hong Kong? 香港科技活動 Innovative Pathway: Hong Kong's New Era of Industry 1 創．造未來 — 香港工業新時代 T. REX 暴龍傳奇 Science Today 今日科學 Can Asteroids Serve as a Food Source for Astronauts? 2 小行星能成為太空人的食物來源嗎？ The Accident That Led to Modern-Day Laser Corrective 6 Eye Surgeries 意外發現：現代激光矯視手術的誕生故事 Amusing World of Science 趣味科學 The Tiny Invaders in Your Home: Dust Mites 10 家居的微小入侵者：塵蟎 The Versatile Baking Soda: 13 From Baking to Graffiti Cleaning 多用途的蘇打粉：從烘焙到清除塗鴉 How to Eat a Pizza Slice Properly? 16 如何不失禮地吃薄餅？ Who’s Who 科言人語 Q&A with HKUST Physics Majors 21 讀物理系的人：與科大學子對談
What’s Happening in Hong Kong? 香港科技活動 Fun in Summer Science Activities 夏日科學好節目 Any plans for this summer? Check out the following events! 計劃好這個夏天的課餘節目了嗎？不妨考慮以下活動！ Innovative Pathway : Hong Kong's New Era of Industry 創．造未來 — 香港工業新時代 Explore the future of Hong Kong’s industry at this special exhibition that put together over 50 exhibits, showcasing cutting-edge technologies and innovative solutions. Discover how local researchers and industrialists are revolutionizing fields like green technology, life sciences, and advanced manufacturing. From electricity-free cooling material to intelligent building robot, these innovations demonstrate the power of Hong Kong's thriving innovation and technology ecosystem. The exhibition also delves into how new industrialization is driving sustainable development and economic growth. 展期： 現在至2025年7月2日 地點： 香港科學館特備展覽廳 入場費： 常設展覽廳參觀人士不另收費。 這個專題展覽展出50 多組展品，以先進技 術及創新方案探索香港工業的前景，揭示本地科 研人員和工業家如何革新綠色科技、生命科學 及先進製造等範疇。由無電製冷材料到智能建 築機械人，這些創新科技展示了香港創科生態圈 的活力。展覽亦探討新型工業化如何推動可持續 發展及經濟進步。 Period: Now – July 2, 2025 Venue: Special Exhibition Hall, Hong Kong Science Museum Admission fee: No extra fee is required for museum visitors of Permanent Exhibitions. T. REX — 暴龍傳奇 Embark on a thrilling journey with the dome show T. REX, where prehistoric giants come to life. Follow a paleontological team as they uncover Tyrannosaurus rex fossils in Montana's Hell Creek Formation in the United States. Through stunning computer-generated imagery and the latest scientific insights, experience the evolution of T. rex into apex predator of the Cretaceous period, and witness dramatic scenes of the dinosaur packhunting Edmontosaurus and battling with Triceratops. Show period: Now – December 14, 2025 Time: 5:00 PM (Mon, Wed to Fri) 11:00 AM, 3:30 PM and 8:00 PM (Sat, Sun and public holiday) Venue: Space Theatre, Hong Kong Space Museum Admission fee: Standard admission: $40 (stalls), $30 (front stalls) Concession admission: $20 (stalls), $15 (front stalls) 放映日期： 現在至2025年12月14日 時間： 下午五時正 （一、三至五） 上午十一時正、下午三時半及八時正 （六、日及公眾假期） 地點： 香港太空館天象廳 入場費： 標準票：40 元（後座）；30 元（前座） 優惠票：20元（後座）；15 元（前座） 球幕電影《暴龍傳奇》邀請大家展開驚險旅 程，跟隨考古隊伍深入美國蒙大拿州地獄溪組 發掘君王暴龍化石，探訪這種在電影中栩栩如生 的史前巨獸。透過結合電腦特效和最新科學發 現，觀眾可以見證君王暴龍演化成白堊紀最強狩 獵者的皇者之路，親歷其成群狩獵埃德蒙頓龍， 以及與三角龍展開生死決鬥的戲劇性場面。 1
Can We Eat Rocks? Imagine you’re an astronaut, floating in the cold, infinite void of space. The isolation is overwhelming, the stars are your only company, and every prepackaged meal reminds you of the tether that ties you to Earth. Bid a farewell to the crusty steak and crunchy toast — nothing is worse than life without the delicious Maillard reaction. Yet, an even more daunting scenario could be the future of dining for astronauts as we explore the possibility of turning asteroid material into sustenance. None of the people on Earth would ever think to ask, "Can we eat rocks or dirt?" — unless you are running out of money. However, always relying on Earth-dependent resupply missions is impractical for prolonged journeys to deep space. Innovative approaches, such as bioregenerative systems that grow plants, algae, mushrooms, or even cultured meat onboard spacecraft, could be promising. However, these systems require a significant amount of resources, including water, light, and nutrients [1, 2]. In comparison, applying the mining concept to food is tantalizing. Could the vast resources of space itself provide sustenance? Scientists are now exploring the possibility of mining asteroids to create food. The carbon-rich asteroids may hold the key, offering a potential source of organic materials that could one day be converted into food for astronauts [2]. The Science Behind Asteroid Food These carbon-rich asteroids, including the famous Murchison meteorite that crash-landed in Australia in 1969, contain organic substances in various forms, such as aliphatic hydrocarbons and insoluble organic matter (IOM) [2]. The food mining process involves feeding relatively short hydrocarbons to bacteria, ideally with carbon lengths from 10 to 40 [2]. Previous studies have identified bacteria that can convert the thermal breakdown products of high-density polyethylene plastic to human edible biomass [3]. Given the similarity in composition between the breakdown products of the plastic and the asteroid material, the microbial consortium is expected to work like a team of microscopic chefs, converting raw asteroid material into food rich in carbohydrates, proteins, and other nutrients humans need to survive [2–4]. Let’s Do Some Math! In the following calculation, asteroid Bennu is chosen to illustrate how much food an asteroid can offer [2]. Bennu is a small, near-earth carbon-rich asteroid with a mass of 7.329 × 1013 g. It was also the target of NASA's first asteroid sample collection mission [5]. A few assumptions are made for the calculation: First, the proportion of organic substances is based on data from the more extensively studied Murchison meteorite. Second, the maximum amount of food is calculated by considering the total amount of insoluble organic matter (IOM) in the asteroid, assuming that they can be extracted and converted into edible biomass. Let’s first find out the mass of IOM in Bennu: The extraction and conversion processes are expected to be somewhat inefficient. Assume the proportion of mass extractable for food production e is 0.32 [3], the conversion efficiency by the bacteria a Food Source for 成為太空 人 小行星能 Can Asteroids Serve as Mass of Bennu × Proportion of IOM = 7.329 × 1013 × 0.096 = 7.036 × 1012 g
3 consortium k1 is 0.2 [3], and the extraction efficiency of carbon material from Bennu k2 is 0.008 [6]. The estimated mass of edible biomass offered by Bennu is: Given that every 100 grams of edible biomass contains a total of 442 Calories, the estimated total Calories offered by Bennu is: A NASA’s standard diet provides 2,500 Calories for one astronaut per day. How many years can Bennu support the need of one astronaut? So, the result is around 17,447 years for one astronaut (or 17,447 astronauts for one year). We’re talking about an asteroid with a volume of around 62.3 million cubic meters — equivalent to about 25,000 Olympic-size swimming pools [7, 8]. To sustain just one astronaut, the daily volume of material required would be roughly the size of a quarter of a 19-seater minibus in Hong Kong [9]. A Long Way to Go A sheer volume of asteroid material would need to be processed daily to sustain even a single astronaut. By Sam Fan 樊潤璋 Astronauts? 人的食物來源嗎？ Handling such a volume in space, where every kilogram of equipment and material must be carefully managed, presents enormous logistical hurdles. For a whole crew of astronauts, demanding storage and processing capacities are almost unfeasible with current technology. So to this day, even if asteroidbased food production is an exciting concept, it is still in its infancy. Future advancements must focus on improving the efficiency of extraction and conversion processes, reducing the asteroid material required, and developing compact, energy-efficient systems that can operate in the unique environment of space [2]. The food will also need to undergo toxicology analysis, animal studies and finally human trials to ensure safety [2]. Only then can this vision become a practical solution for long-term space exploration. A Whole New Horizon While the technology is still theoretical and faces significant challenges, its potential to revolutionize space travel is undeniable. This approach could reduce reliance on Earth’s resources, enabling longer missions to explore the cosmos. Though far from reality, the idea reminds us of humanity’s ingenuity and determination to adapt and thrive, even in the vast, inhospitable reaches of space. Mass of edible biomass ÷ 100 × 442 = 3.602 × 109 ÷ 100 × 442 = 1.592 × 1010 Calories Calories offered by Bennu ÷ 2,500 ÷ 365 = 1.592 × 1010 ÷ 2,500 ÷ 365 = 17,447 years Mass of IOM in Bennu × e × k1 × k2 = 7.036 x 1012 × 0.32 × 0.2 × 0.008 = 3.602 × 109g
算算看！ 在以下的計算中，我們選擇以小行星貝努（Bennu） 來展示一顆小行星到底可以提供多少食物 [2]。貝努是 一顆小型、富含碳元素的近地小行星，質量為7.329 × 1013 克。這顆小行星也是美國太空總署首次執行小行星 樣本收集任務的目標 [5]。以下是一些關於計算的假設： 第一，貝努中有機物所佔之比是從已被廣泛研究的默奇 森隕石的數據中推斷；其次，食物最大產量是基於貝努的 不溶性有機物總量來計算，我們假設這些物質能被提取 並轉化為可食用的生物質。 讓我們先計算貝努中不溶性有機物的質量： 提取和轉化過程的效率預計不會太高。假設不溶性有 機物中可被提取作生產食物之用的質量比e為0.32 [3]、 細菌群落的轉化效率k1 為0.2 [3]，以及從貝努提取有機 物的效率k2 為0.008 [6]。貝努能提供的可食用生物量估 計為： 已知每 100 克可食用生物質含有 442 千卡，貝努可提 供的總熱量估計為： 我們能吃石頭嗎？ 想像一下，你是一名太空人，漂浮在淒冷幽寂、茫無 邊際的虛空中。孤獨感席捲而來，深空中只有天體、星雲 作伴，每份預製餐點都是你與地球有所連結的僅有依據。 向焦香的牛排和香脆的多士告別吧 — 人生在世最糟糕 的事，莫過於失去梅納反應所帶來的絕頂美味。然而，未 來太空人的味蕾可能面臨更嚴峻的挑戰，因為科學家正 探索如何將小行星物質轉化為食物。地球上應該從不會 有人問：「我們能吃岩石或塵土嗎？」－ 除非你已經花光 這個月的零用。不過對於漫長的深空任務來說，一直依賴 地球的補給是不切實際的。 一些創新方案，例如在太空船上培育植物、藻類、蘑菇， 甚至是人造肉的生物再生系統等，也許能被寄予厚望，但 這些系統需要大量資源，包括水、光和養分 [1, 2]。相較之 下，將「開採」的概念用於食物上光想就令人躍躍欲試了。 到底太空豐富的資源能否提供食物來源？科學家正在研究 透過開採小行星來製造食物的可行性，一些富含碳元素的 小行星也許是關鍵，它們蘊含著把有機物轉化為太空人食 物的潛力 [2]。 小行星食物背後的科學 富含碳元素的小行星，包括1969 年墜落在澳洲的著 名默奇森隕石（Murchison meteorite），含有各種形式 的有機物，例如脂肪族烴（aliphatic hydrocarbons）和 不溶性有機物（insoluble organic matter）[2]。從小行 星開採食物的過程正正涉及將較短的碳氫化合物餵給細 菌，理想的碳鏈長度為10到40個碳原子 [2]。先前的研 究發現一些細菌能將高密度聚乙烯塑膠的熱分解產物轉化 為可供人類食用的生物質 [3]。由於那些塑膠的熱分解產 物與小行星物質的成分相似，因此我們能預期微生物群能 像一支微型廚師團隊，將小行星原料轉化為富含碳水化合 物、蛋白質和其他人類生存所需營養的食物 [2–4]。 貝努的質量 × 不溶性有機物所佔之比 = 7.329 × 1013 × 0.096 = 7.036 × 1012 克 貝努中不溶性有機物的質量 × e × k1 × k2 = 7.036 x 1012 × 0.32 × 0.2 × 0.008 = 3.602 × 109 克 可食用生物質的質量 ÷ 100 × 442 = 3.602 × 109 ÷ 100 × 442 = 1.592 × 1010 千卡
5 References 參考資料： [1] Douglas GL, Wheeler RM, Fritsche RF. Sustaining Astronauts: Resource Limitations, Technology Needs, and Parallels between Spaceflight Food Systems and those on Earth. Sustainability. 2021;13(16):9424. doi:10.3390/su13169424 [2] Pilles E, Nicklin RI, Pearce JM. How we can mine asteroids for space food. Int J Astrobiol. 2024;23. doi:10.1017/s1473550424000119 [3] Byrne E, Schaerer LG, Kulas DG, et al. PyrolysisAided microbial biodegradation of HighDensity polyethylene plastic by environmental inocula enrichment cultures. ACS Sustain Chem Eng. 2022;10(6):2022-2033. doi:10.1021/ acssuschemeng.1c05318 [4] Wilkins A. Astronauts could one day end up eating asteroids. New Sci. Published online October 4, 2024. https://www.newscientist.com/article/2450719astronauts-could-one-day-end-up-eating-asteroids/ [5] Barnett A. Bennu. NASA Science. Updated December 17, 2024. Accessed January 22, 2025. https://science. nasa.gov/solar-system/asteroids/101955-bennu/ [6] Zhang L, Dong H, Liu Y, et al. Bioleaching of rare earth elements from bastnaesite-bearing rock by actinobacteria. Chem Geol. 2018;483:544-557. doi:10.1016/j.chemgeo.2018.03.023 [7] Lauretta DS, Bartels AE, Barucci MA, et al. The OSIRIS‐ REx target asteroid (101955) Bennu: Constraints on its physical, geological, and dynamical nature from astronomical observations. Meteorit Planet Sci. 2014;50(4):834-849. doi:10.1111/maps.12353 [8] Bureau of Meteorology, Australian Government. When dam size matters. Updated October 25, 2012. Accessed January 22, 2025. https://media.bom.gov. au/social/blog/39/when-dam-size-matters/ [9] Toyota Hong Kong. Toyota Coaster. Accessed January 22, 2025. https://www.toyota.com.hk/en/our-vehicles/ coaster/ 美國太空總署每天的標準膳食為每名太空人提供 2,500 千卡。那麼，貝努能滿足一名太空人多少年的 食物需求？ 計算結果顯示是長達17,447年（或是為 17,447 名太空人提供一年所需的食物）。我們正 在談論的是體積約為6,230 萬立方米的小行星， 即大小相當於約25,000個奧運標準泳池 [7, 8]。 如果僅為一名太空人提供一天的食物，每天所需 的原材料體積就相當於約四分一輛香港19座公 共小巴 [9]。 漫漫長路 僅為一名太空人提供食物，每天就需要加工大量的小 行星物質。在太空中每公斤的設備和物資都必須受到嚴 格管理，因此要進行這種大規模的處理在安排上並不簡 單。對於餵飽整個太空人團隊來說，所需要的儲存與加工 能力遠遠超出當前技術的可行範圍，因此儘管利用小行星 來生產糧食是個令人興奮的概念，但目前它仍處於構想階 段。 未來發展必須專注於提高提取和轉化過程的效能，減 少所需的小行星原料量，並集中開發精密、節能，且能適 應太空獨特環境的系統 [2]。生產的食品還需經過毒理分 析、動物試驗以及最終的人體試驗，以策安全 [2]。只有 全部達到標準，這構想才能被實際採用於長期太空探索 之中。 嶄新領域 儘管這項技術仍處於理論階段，並且面臨諸多挑戰， 無可否認的是其具備重新定義太空旅行的潛力。這種方法 有望減少對地球資源的依賴，使人類能夠執行更長時間的 宇宙探索任務。雖然目前看來還遙不可及，但這個構想展 現了人類無限的創意與決心，即使在廣闊、荒蕪且嚴酷的 太空，也希望找到生存與發展的方式。 貝努可提供的總熱量 ÷ 2,500 ÷ 365 = 1.592 × 1010 ÷ 2,500 ÷ 365 = 17,447 年
The Accident 意外發現： By Roshni Printer It is fascinating to note that some of the most groundbreaking scientific discoveries happened by chance. Awarded a Golden Goose Award in 2022, one such “accident” in the medical field led to the invention of “bladeless laser-assisted in situ keratomileusis,” a laser corrective eye surgery commonly known as bladeless LASIK. What is LASIK? LASIK is a procedure in which a laser is used to reshape the cornea to treat a range of vision problems, such as myopia (near-sightedness), hyperopia (far-sightedness) and astigmatism [1]. Myopia is a condition where individuals struggle to see distant objects, due to an excessive length of the eyeball or excessive curvature of the lens, leading to the formation of image in front of the retina. In contrast, hyperopia allows individuals to see distant objects but not close objects, due to the short length of the eyeball or insufficient curvature of the lens, so the image forms behind the retina. Another common type of refractive error, astigmatism, is caused by the irregular shape of the cornea or lens. In these conditions, images cannot be sharply focused on the retina, leading to blurry vision. Through a corrective eye surgery, the shape of the cornea can be altered by precisely cutting off some part of the deeper cornea (corneal stroma), so that light can be correctly refracted onto the retina. From a technical point of view, the upper layers of cornea have to be removed before reshaping the stroma. This required a mechanical blade – until a seemingly unrelated lab accident happened [2, 3]. From a Lab Accident to a Successful Startup Back in 1985, physicists Gérard Mourou and Donna Strickland invented a groundbreaking optical technique called “chirped pulse amplification,” which can produce ultrashort laser pulses as short as a femtosecond (10-15 second) with an intensity higher than ever [4]. Mourou later founded the Center for Ultrafast Optical Science at the University of Michigan, and took advantage of this technique to understand chemical reactions [3]. In 1993, one of Mourou’s graduate students working in the center sustained an accidental laser injury to his eye during an experiment [3]. Recalled that he “must have been tired” that evening, Detao Du accidentally lifted his safety goggles, and a stray beam (fortunately not the main beam) of the femtosecond laser produced circular burns to the his retina. Upon examination by Ron Kurtz, a doctor on duty at the University’s eye center, the burns were found to be perfectly circular and precise without damaging any surrounding tissue. Du and Kurtz were both fascinated by the perfect nature of the laser cut, so they decided to collaborate and investigate further. In an optics conference where Du and Kurtz presented their findings, the duo met Tibor Juhasz, a previous member of Mourou’s lab, who was seeking
That Led to Modern-Day Laser Corrective Eye Surgeries 現代激光矯視手術的誕生故事 7 femtosecond laser applications in ophthalmology. This was where the development of bladeless LASIK began. Together they founded a successful startup to commercialize bladeless LASIK, and the company was acquired a decade later for US$808 million in 2007. Notably, Mourou and Strickland were awarded a Nobel Prize in Physics “for their method of generating high-intensity, ultrashort optical pulses” in 2018. LASIK vs SMILE Bladeless LASIK is a well-established option considered to be effective with more than 95% of patients satisfied with the outcome of the surgery [1]. In the surgery, a femtosecond laser is used to create a thin, circular flap of the upper layers of cornea, after which the underlying stromal tissue is reshaped using an excimer laser [5]. The ultraviolet energy (greatly amplified ultraviolet light) emitted by the excimer laser functions to break the organic molecular bonds in the stromal tissue without causing any thermal damage [6]. After precisely removing the stromal tissue, the corneal flap is flipped back to its original position and the cornea is allowed to heal naturally. Recently, a novel refractive surgery procedure known as “small incision lenticule extraction” (SMILE) has also gained popularity since its introduction in 2016 [7]. This minimally invasive procedure adjusts the refractive power of the cornea by carving out a lenticule from the corneal stroma with a femtosecond laser, followed by the extraction of the lenticule through a small incision also made by a femtosecond laser [8]. Primary advantages of SMILE come from its small incision size. LASIK requires cutting a 270 degree, 20 mm circular flap [7], while SMILE involves only a 2–4 mm incision [7, 9]. This greatly reduces the transection of corneal nerves, and hence lessens the experience of dry eyes after the surgery [8]. SMILE also suits contact sport players (e.g. soccer and martial arts) more because it does not involved a corneal flap which may move in some unlikely cases [8, 10]. Additionally, SMILE was also found to be more stable in high myopia [8]. For the downside, LASIK allows touch-ups to finetune vision after some years, but this is not possible for SMILE [7]. If an enhancement procedure is needed for an eye treated by SMILE, the options are to perform LASIK or an older PRK technique (footnote 1) on the SMILE cap. In addition, SMILE has not been approved to treat hyperopia in the US, so LASIK remains the only choice for people with far-sightedness at the moment [8]. While both procedures demonstrate efficacy and safety, the choice between SMILE and LASIK ultimately depends on individual patients and specific eye conditions. Please seek medical advice from your eye doctor if you are considering one of these corrective eye surgeries.
一些重要的科學發現往往出於偶然。獲頒 2022 年金 鵝獎的醫學界發明正正出於一件意外，最終啟發科學家開 創「無刀雷射屈光角膜層狀重塑術」（bladeless laserassisted in situ keratomileusis），亦是街知巷聞的「無 刀 LASIK」激光矯視手術。 甚麼是 LASIK？ LASIK 是一種矯視手術，透過使用激光重塑角膜形 狀來治療一系列的視力問題，例如近視、遠視和散光 [1]。 近視患者由於眼球過長或晶體曲率過大，導致影像在視 網膜前方形成，使患者難以看清遠物。相反，遠視患者能 看清遠物而非近物，這是由於眼球過短或晶體曲率不足， 導致影像在視網膜後方形成。另一種常見屈光不正的類 型是散光，它是由於角膜或晶體形狀不規則造成。在這三 種情況，影像皆無法清晰聚焦在視網膜上，導致視力模糊。 矯視手術是透過精確切除角膜內層（角膜基質）的部分 組織來改變角膜的形狀，使光線能正確折射到視網膜上。 技術上，重塑基質前必先移除表層角膜，這得用上手術 刀 — 直到一次看似無關的實驗室意外 [2, 3]。 從實驗室意外到成功的初創企業 1985 年，物 理 學 家 Gérard Mourou 和 Donna Strickland 發明了一種名為「啁啾脈衝放大」的突破性光 學技術，製造出短至飛秒（10-15 秒），但強度前所未有地 高的超短激光脈衝 [4]。Mourou其後在密歇根大學創 立了超快光學科學中心（Center for Ultrafast Optical Science），利用這項技術研究化學反應 [3]。 1993 年，Mourou 的研究生杜德濤在一次實驗意外中 被激光所傷 [3]。他憶述當晚「肯定是太累」，所以不慎移除 了護目鏡，結果被一束飛秒激光的雜散光（幸好不是主光 束）擊傷視網膜，造成了圓形的燒傷。經大學眼科中心值班 醫生Ron Kurtz的檢查後，發現燒傷的形狀是完美的圓形， 而且精確得很，絲毫沒有破壞周邊組織。杜德濤和 Kurtz 都為這種完美的激光切割特性所著迷，因此決定合作對此 進一步研究。 杜德濤和Kurtz在一次光學會議上匯報發現， 二人在此遇見Mourou實驗室的前成員Tibor Juhasz，後者剛好正尋找飛秒激光在眼科上的應用。他 們一拍即合，為無刀 LASIK 的發展揭開序幕。他們共同 創立了一家成功的初創公司，將無刀 LASIK 技術推出市 場。該公司最終於十年後的2007年以8.08億美元被 高價收購。另一方面，為故事畫龍點晴的是 Mourou 和 Strickland 亦因「研發出製造高強度超短光脈衝的方 法」於 2018 年獲得諾貝爾物理學獎。 LASIK 與 SMILE 無刀LASIK 是發展成熟的技術，超過95%的患者對 手術結果感到滿意 [1]。手術中，醫生會使用飛秒激光在 角膜表層切出一個薄的圓形角膜瓣，然後使用準分子雷射 （excimer laser）重塑底層基質組織的形狀 [5]。準分子激 光發出的紫外線能量（經大幅增強的紫外光）能打破基質 1. PRK: Photorefractive keratectomy (PRK) is an older technique which requires scraping off the upper layers of cornea (instead of creating a flap which will be flipped back to its original position). The tissue will then be allowed to regrow, but the healing process can take several weeks [11]. Summary While what happened to be an accidental discovery turned into one of the most sought-after medical procedures in modern-day ophthalmology, many researchers, including Kurtz and Juhasz, continue to explore novel applications of the femtosecond laser for eye diseases such as glaucoma and cataract [3]. This story shows the impact of chance on scientific progress, standing testament to the fact that life-changing discoveries can occur any time of the day – so keep an eye out!
References 參考資料： [1] Kates, M. M., & Tuli, S. (2020). What Is LASIK Eye Surgery?. JAMA, 324(8), 815. https://doi.org/10.1001/ jama.2020.1286 [2] Barraquer, J. I. (1996). The History and Evolution of Keratomileusis. International Ophthalmology Clinics, 36(4), 1–7. https://doi.org/10.1097/00004397-19960364000003 [3] Asbury, M. (n.d.). How a Lab Incident Led to Better Eye Surgery for Millions of People. The Golden Goose Award. https://www.goldengooseaward. org/01awardees/lasik [4] Rose, J. (n.d.). The Nobel Prize in Physics 2018 - Popular science background: Tools made of light. The Nobel Prize. https://www.nobelprize.org/prizes/physics/2018/ popular-information/ [5] Department of Ophthalmology, Hong Kong Sanatorium & Hospital. (n.d.). Laser-assisted In-situ Keratomileusis (LASIK). https://www.hksh-hospital.com/oph/en/ourservices/lasik.php [6] Trokel, S. L., Srinivasan, R., & Braren, B. (1983). Excimer Laser Surgery of the Cornea. American Journal of Ophthalmology, 96(6), 710–715. https://doi.org/10.1016/ s0002-9394(14)71911-7 [7] Stephenson, M. (2021, April 15). The Current State of SMILE vs. LASIK. Review of Ophthalmology. https://www. reviewofophthalmology.com/article/the-current-stateof-smile-vs-lasik [8] Shah, R. (2019). History and Results; Indications and Contraindications of SMILE Compared With LASIK. AsiaPacific Journal of Ophthalmology, 8(5), 371–376. https:// doi.org/10.1097/01.APO.0000580132.98159.fa [9] Moshirfar, M., Somani, S. N., & Patel, B. C. (2024, February 26). Small Incision Lenticule Extraction. StatPearls. https://www.ncbi.nlm.nih.gov/books/ NBK549896/ [10] Cleveland Clinic. (2024, February 5). LASIK vs. SMILE: Which Is Right for You? https://health.clevelandclinic. org/lasik-vs-smile [11] Oliver, B. (2024, January 31). LASIK vs. PRK: Which Laser Eye Surgery Is Right for You? John F. Hardesty, MD, Department of Ophthalmology & Visual Sciences. https://ophthalmology.wustl.edu/lasik-vs-prk-whichlaser-eye-surgery-is-right-for-you/ 組織中的有機分子鍵而不造成任何燒傷 [6]。在精確打磨 基質組織後，角膜瓣會被掀回原位，允許角膜自然癒合。 近年，名為「小切口透鏡切除術」（small incision lenticule extraction / SMILE）的新型激光矯視手術 自2016年引入以來也受到廣泛關注 [7]，這種微創手術 利用飛秒激光在角膜基質中刻出一個透鏡狀的組織，然 後從同樣由飛秒激光切割出的微細切口將組織取出，從 而調整角膜的屈光能力 [8]。 SMILE 的主要優勢來自其微細的切口大小。LASIK 需 要切割長達20毫米的270度圓形角膜瓣 [7]，但SMILE 僅需要二至四毫米的切口 [7, 9]，這樣能避免大量切斷角 膜神經，有效減少手術後眼乾的情況 [8]。另外如果患者 熱衷於身體接觸較多的運動，例如足球或武術等，SMILE 會更為適合，因為過程中不需要切出角膜瓣，所以角膜瓣 不會在運動中被意外掀開 [8, 10]。此外，SMILE在近視 度數較高的情況下也能維持更穩定的效果 [8]。 至於缺點，LASIK允許在手術後數年進行輕微修 正以調整視力，但SMILE則不支援後續微調 [7]。如 果接受SMILE後需要進一步調整視力，選擇只有接受 LASIK 手術，或在 SMILE 的結構上進行第一代的 PRK 手術（註一）。此外，SMILE 在美國尚未獲得批准治療遠 視，因此LASIK目前仍是遠視患者的唯一選擇 [8]。 儘管 SMILE 和 LASIK 的療效和安全性均被認可，但 最終選擇何者取決於患者意願及其眼部狀況。如果有意 進行矯視手術，請諮詢眼科醫生以獲取專業意見。 總結 雖然這個偶然的發現已成為了現代眼科最受歡迎的醫 療程序之一，但包括 Kurtz 和 Juhasz在內許多研究人員 仍在探索飛秒激光於青光眼和白內障等眼科疾病中的嶄 新應用 [3]。這個故事展示了始料不及的意外也能為科學 發展帶來深遠影響，證明了改變人類生活的發現隨時都可 能發生 — 所以請細心留意周遭一切！ 1. PRK：屈光角膜切除術（photorefractive keratectomy / PRK）是一種較 舊的技術，當中表層角膜會被完全移除（而不是切出一個稍後會被掀回原位 的角膜瓣），然後等待組織重新生長，但癒合過程可以長達數週 [11]。 9
By Jane Yang 楊靜悠 When it comes to allergies, many people think of pollen or pet dander. But did you know that one of the most common culprits might be lurking in the dust? Meet the dust mite, a tiny creature that can wreak havoc on your immune system. In this article, we will answer some common questions about dust mites, why they are so problematic, and how you can reduce their presence in your home. What Are Dust Mites? Dust mites are microscopic creatures with a body size as small as a quarter of a millimeter that you can hardly see them without a microscope [1, 2]. Unlike insects, which have six legs, adult dust mites are close relatives to spiders and ticks, so they have eight legs [2]. Another key difference between insects and arachnids also lies in their anatomy. Insects have three main body segments – head, thorax and abdomen, whereas arachnids only have two – cephalothorax and abdomen (footnote 1) [3]. While dust mites don’t spin webs like spiders or suck blood like ticks, they are just as persistent. These tiny creatures thrive in warm, humid environments. A relative humidity of 75% is ideal for their proliferation, at which they can absorb sufficient water vapor with their specialized glands, the supracoxal glands, above the first pair of legs [2, 4]. The hypertonic sodium and potassium chloride solution secreted by the glands facilitates water absorption through osmosis. This body feature enables dust mites to survive for 65–100 days and lay 30–80 eggs during their lifetime at room temperature. At a higher temperature of 30°C, dust mites mature into adult and start reproducing much faster (from 35 to 17.5 days for Dermatophagoides farinae) [2, 5], making them a tough opponent in the battle for a clean home. Dust mites feed on dead skin cells shed by humans and pets. This means they love to settle into places like bedding, mattresses, carpets, curtains, and upholstered furniture [1, 2]. If you’ve been sneezing or itching at home, dust mites might be the hidden cause. 家居的微小入侵者： The Tiny Invaders in Your Home: 塵蟎 Dust Mites
11 How Can Dust Mites Cause Allergies? Despite their tiny size, dust mites can cause massive problems for allergy sufferers. The trouble comes from certain proteins found in their feces, urine and dead bodies [6]. Inhaling these proteins, known as allergens, may trigger an overreaction of the immune system in some people. In these cases, your immune system mistakenly identifies them as invaders and sets off an allergic reaction, inducing the following typical allergy symptoms [1, 6]: sneezing, runny or stuffy nose, watery eyes, itchy skin or rashes, and coughing. In severe cases, it can trigger asthma attacks. The allergens are microscopic, so they can easily become airborne when you vacuum, sit on furniture, or make your bed, which makes them hard to avoid. However, there are still methods to reduce the threat of dust mites. How Can You Reduce the Level of Dust Mites? 1) Keep humidity low Dust mites thrive in warm, humid environments. Using a dehumidifier or air conditioner to keep indoor humidity below 50% makes them harder to survive and reproduce [6] because the water balance can’t be maintained at the supracoxal glands, so adult dust mites will dehydrate and eventually die [2]. 2) Wash bedding frequently Since dust mites love to live in your bedding, make it a habit to wash your sheets, pillowcases, and blankets in hot water every week. A water temperature higher than 60°C can effectively kill dust mites and their eggs [1, 2]. 3) Dust regularly Dust hard surfaces regularly with a damp cloth to avoid stirring allergens into the air [6]. 4) Minimize dust-collecting surfaces Reduce clutter and avoid heavy fabrics like curtains or upholstered furniture [1, 6]. Opt for washable shades and hard flooring, such as wood or tile instead of carpets. If this is not possible, vacuum your carpets and rugs by using a vacuum cleaner with a HEPA (high efficiency particulate air) filter, which can trap dust mites and their allergens [6]. 1. Cephalothorax: The prefix “cephalo-” means head in Latin, so “cephalothorax” refers to the fused head and thorax of arachnids. 談到過敏，許多人會想到花粉或寵物皮屑。但你知道嗎？ 另一個常見的元兇就隱藏在灰塵中 — 牠就是塵蟎，這種微 小生物可以搞亂你的免疫系統。在這篇文章，我們將回答一 些關於塵蟎的常見問題，解釋牠們為何如此令人困擾，並提 供一些減少家中塵蟎的方法。 甚麼是塵蟎？ 塵蟎是一種微小的生物，體型僅有四分之一毫米，幾乎無 法用肉眼看見，要用顯微鏡觀看 [1, 2]。 與有六隻腳的昆蟲不同，塵蟎是蜘蛛和蜱蟲的近親，因 此成蟲有八隻腳 [2]。昆蟲和蛛形綱動物之間的另一個關鍵 區別在於牠們的身體結構，昆蟲有三個主要身體部分 — 頭 部、胸部和腹部，而蛛形綱動物只有兩個 — 頭胸部和腹部 （註一）[3]。 雖然塵蟎不像蜘蛛那樣結網，也不像蜱蟲那樣吸血，但 牠們同樣頑強。這些微小生物會在溫暖潮濕的環境中快速 生長，75%的相對濕度是牠們繁殖的理想條件。在這種濕 度下，牠們可以通過位於第一對腳上方，名為「基節上腺」 的特殊腺體吸收足夠的水分 [2, 4]，這些腺體分泌的高滲鈉 Remember, while you can’t see dust mites, you can certainly feel their effects — and now, you know how to fight back!
和氯化鉀溶液能促進經滲透作用的水分吸收。這個身體特 徵使塵蟎能在室溫下存活 65至 100 天，並產下30至80 顆卵。在比正常室溫高的30°C 下，塵蟎會成熟得更快並更 早開始繁殖（以Dermatophagoides farinae為例，成熟時 間會從35天縮短到17.5天）[2, 5]，使牠們成為保持家居 清潔的戰鬥中一個難纏的對手。 塵蟎以人類和寵物脫落的死皮為食，意味著牠們喜歡棲 息在床單、床褥、地毯、窗簾和軟墊家具等地方 [1, 2]。如果 你在家裡經常打噴嚏或發癢，塵蟎可能就是隱藏的元兇。 塵蟎如何引發過敏？ 儘管塵蟎體型微小，但牠們可以對過敏患者構成極大困 擾。問題來自牠們的糞便、尿液和屍體中的某些蛋白質 [6]， 吸入這些稱為過敏原的蛋白質可能會引發某些人免疫系統 的過度反應。在這種情況下，你的免疫系統會錯誤地將這些 蛋白質識別為入侵者，並啟動過敏反應，導致以下典型的過 敏症狀 [1, 6]：打噴嚏、流鼻水或鼻塞、流淚、皮膚瘙癢或 皮疹，以及咳嗽；在嚴重的情況下更能引發哮喘發作。 這些過敏原非常微小，因此當你吸塵、坐到沙發上或整 理床鋪時，它們很容易就會飄散到空氣中，使得它們難以避 免，但仍然有一些方法可以減少塵蟎的威脅。 如何減少塵蟎？ 1) 控制濕度 溫暖潮濕的環境有助塵蟎繁殖。使用抽濕機或空調將 室內濕度保持在50%以下能使牠們不易生存和繁殖 [6]， 因為基節上腺再無法維持水分平衡，塵蟎成蟲會最終會因 脫水而死亡 [2]。 2) 經常清洗床單 由於塵蟎喜歡居住在床單上，我們應養成每週用熱水清 洗床單、枕套和毯子的習慣。高於 60°C的水溫可以有效殺 死塵蟎及其卵 [1, 2]。 3) 定期除塵 定期用濕布清潔家居以免將過敏原揚到空氣中 [6]。 4) 減少積塵的表面 減少雜物，並避免使用厚重的窗簾或軟墊家具 [1, 6]。 選擇可清洗的窗簾和硬地板，如木地板或瓷磚等，避免使用 地毯。如果不得不使用地毯，請使用帶有 HEPA 過濾器（高 效率粒子空氣過濾器）的吸塵器清潔地毯和地墊，這種過濾 器可以捕捉塵蟎及其過敏原 [6]。 記住，雖然你看不到塵蟎，但你一定能感受到牠們的影 響 — 現在，你知道如何反擊了！ 1. 頭胸部：蛛形綱動物頭部和胸部融合在一起的結構。 References 參考資料： [1] Asthma and Allergy Foundation of America. (2015, October). Dust Mite Allergy. https://aafa.org/allergies/ types-of-allergies/insect-allergy/dust-mite-allergy/ [2] Miller, J. D. (2019). The Role of Dust Mites in Allergy. Clinical Reviews in Allergy & Immunology, 57, 312–329. https://doi.org/10.1007/s12016-018-8693-0 [3] National Park Service, U.S. Department of the Interior. (2021, May 9). Insects and Arachnids. https://www.nps. gov/ocmu/learn/nature/insects.htm [4] Arlian, L. G., & Platts-Mills, T. A. E. (2001). The biology of dust mites and the remediation of mite allergens in allergic disease. Journal of allergy and clinical immunology, 107(3 Suppl), S406–S413. https://doi. org/10.1067/mai.2001.113670 [5] Denmark, H. A., & Cromroy, H. L. (2020, June). house dust mites - Dermatophagoides spp. Institute of Food and Agricultural Sciences, University of Florida. https:// entnemdept.ufl.edu/creatures/urban/house_dust_ mite.htm [6] American Lung Association. (2024, November 5). Dust mites. https://www.lung.org/clean-air/indoor-air/ indoor-air-pollutants/dust-mites
多用途的蘇打粉：從烘焙到清除塗鴉 The Versatile Baking Soda: From Baking to Graffiti Cleaning 13 What is Baking Soda? Baking soda, scientifically known as sodium bicarbonate (NaHCO3), can be found in almost every household counter. Despite its name, most people keep baking soda in their homes not because of their baking passion, but due to its wide applications. Sodium bicarbonate is a weak base that has an alkaline pH range of eight to nine when dissolved in water. This article will explore some uses of baking soda within and beyond your home. Baking Fluffy Pastries In baking, sodium bicarbonate serves primarily as a leavening agent [1, 2]. When reacted with the acidic ingredients in a recipe — such as cream of tartar, lemon juice, or yogurt — baking soda undergoes an acid-base reaction to produce carbon dioxide gas, causing the dough or batter to rise and create the fluffy texture of baked goods. The acid-base reaction alone can take place at room temperature, but sodium bicarbonate also undergoes thermal decomposition at temperatures above 50°C to produce extra carbon dioxide (table 1). However, it is crucial to strike a balance between the amount of acid and base in a recipe. An excess of baking soda can lead to a bitter and metallic taste due to the unreacted sodium bicarbonate. In fact, a product called baking powder aims to ease this task, as it consists of both sodium bicarbonate and powdered acids already mixed in a right proportion [1]. Combating Foul Smell from Trash Bin Another handy household application of baking soda comes from its ability to neutralize odors. The offensive smells produced by the anaerobic decomposition of organic waste in your trash bin can be attributed to volatile fatty acids and ammonia [3, 4]. A study found that spreading 50 grams of baking soda at the bottom of an eight-liter food waste bin could reduce odors by 70% [3]. Baking soda can mitigate the unpleasant odors by neutralizing odor-producing acids, turning the volatile acids into involatile salts [5]. For example, as a volatile acid with a boiling point of 164°C [6], the vaporization of a small portion of butyric acid can already give an odor like rancid butter. Sodium bicarbonate can neutralize the acid to sodium butyrate, a solid with a melting temperature of 250°C, so it will require a much higher temperature to vaporize [7]. This simple method showcases the practicality of By Daria Zaitseva Acid-base reaction: NaHCO3(s) + H+(aq) → Na+(aq) + CO2(g) + H2O(l) Thermal decomposition: 2 NaHCO3(s) ⇌ Na2CO3(s) + CO2(g) + H2O(l) Table 1 The two reactions of sodium bicarbonate that produce carbon dioxide during baking.
表一 碳酸氫鈉在烘焙過程中產生二氧化碳的兩種反應。 the compound in maintaining a fresher environment within kitchens, with a possibility of extension to local food waste collection points. Maintaining Dental Hygiene Baking soda doesn’t just shine in kitchens; it can also safeguard our dental health. It is used as an abrasive agent in dental air polishing by dentists to remove teeth stains [8]. Similarly, you might have seen baking soda as an ingredient in a toothpaste formula; it is added to polish and remove dental plaque and stains with the help of a toothbrush [9]. While other common abrasives in toothpaste, such as hydrated silica and calcium pyrophosphate, rely solely on physical scrubbing, the alkaline and bactericidal properties of baking soda can provide additional protection against cavities (tooth decay) [9]. After the ingestion of sugary foods, oral bacteria will metabolize the carbohydrates and produce organic acids which lower the oral pH. It is known that the solubility of enamel significantly increases when the pH is lower than 5.1–5.5, causing the demineralization (or the loss) of enamel [9, 10]. Research has shown that brushing teeth with a baking soda-based toothpaste after a meal can prevent cavities by restoring the oral pH. In addition, baking soda was also found to have bactericidal effects on various bacteria found in dental plaque, such as Streptococcus mutans, especially when used in combination with hydrogen peroxide [9]. Removing Graffiti and Stains by Soda Blasting Akin to how dentists use baking soda as abrasives to clean our teeth, soda blasting is a technique that rids the streets from graffiti paint and other stains [11]. By shooting fine particles of baking soda in compressed air or water at a pressure as low as 140 kPa, paint or rust on delicate materials like wood, masonry and copper can be removed. It is a milder method than sandblasting, which operates at 550–1,050 kPa and optimized for tougher surfaces like aircraft parts and concrete. In addition, compared to other common abrasive blasting substances, such as slags [12], soda blasting poses less risk to the respiratory health of workers, and is kinder to the environment as a non-toxic compound. The Versatile Baking Soda Summing up, baking soda is a remarkable compound with diverse applications in culinary, cleaning, and many other fields. Not only does it produce fluffy pastries, but it is also applied to keep our environment clean, our bins fresh, and our oral cavity healthy. As researchers continue to look for broader applications, baking soda will remain a versatile compound for us all. 甚麼是蘇打粉？ 蘇打粉在科學上又名碳酸氫鈉（NaHCO3），幾乎可以 在每個家庭的料理枱上找到。儘管它是眾所周知的烘焙用 品，但大多數人家裡擁有蘇打粉的原因並不是因為他們熱 愛烘焙，而是因為它在其他範疇上的用途。碳酸氫鈉是一 種弱鹼，當溶解在水中時，其酸鹼值範圍為鹼性的八至九。 本文將探討蘇打粉在家庭內外的應用。 烘焙蓬鬆糕點 在烘焙中，碳酸氫鈉主要被用作膨脹劑 [1, 2]。蘇打粉 會與食譜中的酸性成分（如他他粉、檸檬汁或乳酪等）發生 酸鹼反應，產生二氧化碳，使麵團或麵糊膨脹而造出糕點 蓬鬆的質地。酸鹼反應可以在室溫下進行，但碳酸氫鈉在 超過 50°C的溫度下也會進行熱分解，產生額外的二氧化 碳（表一）。 酸鹼反應： NaHCO3(s) + H+(aq) → Na+(aq) + CO2(g) + H2O(l) 熱分解： 2 NaHCO3(s) ⇌ Na2CO3(s) + CO2(g) + H2O(l)
References 參考資料： [1] Wang, C. (2022, May 19). What’s the Difference Between Baking Soda and Baking Powder? Office for Science and Society, McGill University. https://www. mcgill.ca/oss/article/student-contributors-generalscience/whats-difference-between-baking-soda-andbaking-powder [2] Graves, A, & Qualmann, K. (2018, August 3). The Science of Baking Soda. ACS Axial. https://axial.acs. org/cross-disciplinary-concepts/the-science-ofbaking-soda [3] Qamaruz-Zaman, N., Kun, Y., & Rosli, R. N. (2015). Preliminary observation on the effect of baking soda volume on controlling odour from discarded organic waste. Waste Management, 35, 187–190. https://doi. org/10.1016/j.wasman.2014.09.017 [4] Mackie, R. I., Stroot, P. G., & Varel, V. H. (1998). Biochemical identification and biological origin of key odor components in livestock waste. Journal of Animal Science, 76(5), 1331–1342. https://doi. org/10.2527/1998.7651331x [5] Schwarcz, J. (2017, October 30). Can baking soda really absorb odors in the fridge? Office for Science and Society, McGill University. https://www.mcgill.ca/oss/ article/general-science-you-asked/can-baking-sodareally-absorb-odors-fridge [6] National Center for Biotechnology Information. (2025). PubChem Compound Summary for CID 264, Butyric Acid. https://pubchem.ncbi.nlm.nih.gov/compound/ Butyric-Acid [7] ACS Chemistry for Life. (2021, October 11). Sodium butyrate - American Chemical Society. https://www. acs.org/molecule-of-the-week/archive/s/sodiumbutyrate.html [8] Hongsathavij, R., Kuphasuk, Y., & Rattanasuwan, K. (2017). Clinical comparison of the stain removal efficacy of two air polishing powders. European Journal of Dentistry, 11(3), 370–375. https://doi. org/10.4103/ejd.ejd_152_17 [9] Myneni, S. R. (2017). Effect of baking soda in dentifrices on plaque removal. The Journal of the American Dental Association, 148(11S), S4–S9. https://doi. org/10.1016/j.adaj.2017.09.004 [10] Kolumban, A., Moldovan, M., Tig, I. A., Chifor, I., Cuc, S., Bud, M., & Badea, M. E. (2021). An Evaluation of the Demineralizing Effects of Various Acidic Solutions. Applied Sciences, 11(17), 8270. https://doi. org/10.3390/app11178270 [11] Khodair, Y. A., Ahmed, M. M., Perala, V. S., & Shareef, M. S. (2024). Anti-Graffiti Protection Systems. Illinois Center for Transportation. https://doi.org/10.36501/0197-9191/24022 [12] Neulicht, R., & Shular, J. (1997, September). Emission Factor Documentation for AP-42, Section 13.2.6, Abrasive Blasting – Final Report. U.S. Environmental Protection Agency Office of Air Quality Planning and Standards Emission Factor and Inventory Group. https:// www.epa.gov/sites/default/files/2020-10/documents/ section_13.2.6_abrasive_blasting.pdf 15 可是，在食譜中平衡酸和鹼的量至關重要，因為沒有 與酸反應的過量蘇打粉會使成品出現苦味和金屬味。事 實上，一種名為「泡打粉」的產品旨在避免這種情況，因為 它是由已按正確比例混合的碳酸氫鈉和粉狀酸組成 [1]。 消除垃圾桶異味 蘇打粉另一個實用的家用用途是中和氣味。垃圾桶中 的惡臭主要來自厭氧分解有機廢物時產生的揮發性脂肪 酸和阿摩尼亞 [3, 4]。研究發現在八公升廚餘桶底部撒 50克蘇打粉能減少70%異味 [3]。蘇打粉透過中和脂肪 酸減輕異味，過程將揮發性脂肪酸轉化為不帶揮發性的 鹽 [5]，以丁酸為例，作為一種沸點為164°C的揮發性酸 [6]，少量丁酸揮發就能引起腐敗牛油的氣味，而碳酸氫鈉 可以將丁酸中和產生丁酸鈉，它是一種熔點為 250°C 的 固體，因此需要高很多的溫度才會揮發 [7]。這種簡單方 法展示了蘇打粉在消除廚房異味方面的實用性，此做法更 有可能在未來被擴展到社區廚餘收集點。 保持口腔衛生 蘇打粉不僅在廚房發光發亮，亦能守護我們牙齒健康。 它在噴砂洗牙中被牙醫用作研磨劑去除牙齒污漬 [8]。同 樣地，你可能也看過牙膏配方中含有蘇打粉，它的作用是 在牙刷的幫助下打磨並去除牙菌膜和污漬 [9]。 相對於牙膏中其他常見的研磨劑（例如水合二氧化矽 和焦磷酸鈣）僅靠物理研磨，蘇打粉的鹼性和殺菌特性能 進一步降低齲齒（蛀牙）的風險 [9]。在攝取含糖的食物後， 口腔細菌會代謝碳水化合物並產生有機酸，降低口腔的酸 鹼值。已知當酸鹼值低於 5.1 至 5.5 時，琺瑯質的溶解度 會顯著增加，導致琺瑯質流失 [9, 10]。研究顯示飯後使用 含蘇打粉的牙膏刷牙有助恢復口腔酸鹼值，預防蛀牙。此 外，尤其在與過氧化氫發揮共同作用的情況下，蘇打粉也 對牙菌膜中包括變形鏈球菌（Streptococcus mutans）在 內的多種細菌具殺菌作用 [9]。 去除塗鴉和污漬的蘇打噴砂 類似於牙醫使用蘇打粉作為研磨劑清潔我們的牙齒， 蘇打噴砂是一種可以清除街道上塗鴉和其他污漬的技術 [11]。透過把幼細的蘇打粉加入壓縮空氣或水中，並以低 至140 kPa的壓力射向木材、磚石和銅等較脆弱的材料， 其表面上的油漆或鏽蝕便能得以清除。傳統噴砂的操作壓 力為550–1,050 kPa，主要用於更堅硬的表面，例如飛機 部件和混凝土等，因此蘇打噴砂是比傳統噴砂更溫和的方 法。此外，與礦渣等其他常見的研磨材料相比 [12]，由於蘇 打粉是不帶毒性的化合物，所以蘇打噴射對工人的呼吸健 康風險較小，亦對環境更為友善。 用途廣泛的蘇打粉 總結來說，蘇打粉是具有多用途的化合物，涵蓋烹飪、 清潔及其他許多領域。它不僅能製作鬆軟的糕點，亦能用 於保持環境清潔，對付垃圾桶異味和維持口腔健康。隨著 研究人員不斷尋找更廣泛的應用，蘇打粉將繼續是我們實 用的好幫手。
ebookshelf.ust.hkRkJQdWJsaXNoZXIy NDk5Njg=